6 @documentencoding UTF-8
7 @settitle GNU Guix Reference Manual
12 @c Identifier of the OpenPGP key used to sign tarballs and such.
13 @set OPENPGP-SIGNING-KEY-ID 3CE464558A84FDC69DB40CFB090B11993D9AEBB5
16 Copyright @copyright{} 2012, 2013, 2014, 2015, 2016 Ludovic Courtès@*
17 Copyright @copyright{} 2013, 2014, 2016 Andreas Enge@*
18 Copyright @copyright{} 2013 Nikita Karetnikov@*
19 Copyright @copyright{} 2014, 2015, 2016 Alex Kost@*
20 Copyright @copyright{} 2015, 2016 Mathieu Lirzin@*
21 Copyright @copyright{} 2014 Pierre-Antoine Rault@*
22 Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer@*
23 Copyright @copyright{} 2015, 2016 Leo Famulari@*
24 Copyright @copyright{} 2015, 2016 Ricardo Wurmus@*
25 Copyright @copyright{} 2016 Ben Woodcroft@*
26 Copyright @copyright{} 2016 Chris Marusich@*
27 Copyright @copyright{} 2016 Efraim Flashner@*
28 Copyright @copyright{} 2016 John Darrington@*
29 Copyright @copyright{} 2016 ng0@*
30 Copyright @copyright{} 2016 Jan Nieuwenhuizen@*
31 Copyright @copyright{} 2016 Julien Lepiller@*
32 Copyright @copyright{} 2016 Alex ter Weele
34 Permission is granted to copy, distribute and/or modify this document
35 under the terms of the GNU Free Documentation License, Version 1.3 or
36 any later version published by the Free Software Foundation; with no
37 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
38 copy of the license is included in the section entitled ``GNU Free
39 Documentation License''.
42 @dircategory System administration
44 * Guix: (guix). Manage installed software and system configuration.
45 * guix package: (guix)Invoking guix package. Installing, removing, and upgrading packages.
46 * guix build: (guix)Invoking guix build. Building packages.
47 * guix gc: (guix)Invoking guix gc. Reclaiming unused disk space.
48 * guix pull: (guix)Invoking guix pull. Update the list of available packages.
49 * guix system: (guix)Invoking guix system. Manage the operating system configuration.
52 @dircategory Software development
54 * guix environment: (guix)Invoking guix environment. Building development environments with Guix.
59 * Guix user interface: (guix)Emacs Interface. Package management from the comfort of Emacs.
64 @title GNU Guix Reference Manual
65 @subtitle Using the GNU Guix Functional Package Manager
66 @author The GNU Guix Developers
69 @vskip 0pt plus 1filll
70 Edition @value{EDITION} @*
78 @c *********************************************************************
82 This document describes GNU Guix version @value{VERSION}, a functional
83 package management tool written for the GNU system.
86 * Introduction:: What is Guix about?
87 * Installation:: Installing Guix.
88 * Package Management:: Package installation, upgrade, etc.
89 * Emacs Interface:: Using Guix from Emacs.
90 * Programming Interface:: Using Guix in Scheme.
91 * Utilities:: Package management commands.
92 * GNU Distribution:: Software for your friendly GNU system.
93 * Contributing:: Your help needed!
95 * Acknowledgments:: Thanks!
96 * GNU Free Documentation License:: The license of this manual.
97 * Concept Index:: Concepts.
98 * Programming Index:: Data types, functions, and variables.
101 --- The Detailed Node Listing ---
105 * Binary Installation:: Getting Guix running in no time!
106 * Requirements:: Software needed to build and run Guix.
107 * Running the Test Suite:: Testing Guix.
108 * Setting Up the Daemon:: Preparing the build daemon's environment.
109 * Invoking guix-daemon:: Running the build daemon.
110 * Application Setup:: Application-specific setup.
112 Setting Up the Daemon
114 * Build Environment Setup:: Preparing the isolated build environment.
115 * Daemon Offload Setup:: Offloading builds to remote machines.
119 * Features:: How Guix will make your life brighter.
120 * Invoking guix package:: Package installation, removal, etc.
121 * Substitutes:: Downloading pre-built binaries.
122 * Packages with Multiple Outputs:: Single source package, multiple outputs.
123 * Invoking guix gc:: Running the garbage collector.
124 * Invoking guix pull:: Fetching the latest Guix and distribution.
125 * Invoking guix archive:: Exporting and importing store files.
129 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
130 * Package Management: Emacs Package Management. Managing packages and generations.
131 * Licenses: Emacs Licenses. Interface for licenses of Guix packages.
132 * Package Source Locations: Emacs Package Locations. Interface for package location files.
133 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
134 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
135 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
136 * Completions: Emacs Completions. Completing @command{guix} shell command.
137 * Development: Emacs Development. Tools for Guix developers.
138 * Hydra: Emacs Hydra. Interface for Guix build farm.
140 Programming Interface
142 * Defining Packages:: Defining new packages.
143 * Build Systems:: Specifying how packages are built.
144 * The Store:: Manipulating the package store.
145 * Derivations:: Low-level interface to package derivations.
146 * The Store Monad:: Purely functional interface to the store.
147 * G-Expressions:: Manipulating build expressions.
151 * package Reference:: The package data type.
152 * origin Reference:: The origin data type.
156 * Invoking guix build:: Building packages from the command line.
157 * Invoking guix edit:: Editing package definitions.
158 * Invoking guix download:: Downloading a file and printing its hash.
159 * Invoking guix hash:: Computing the cryptographic hash of a file.
160 * Invoking guix import:: Importing package definitions.
161 * Invoking guix refresh:: Updating package definitions.
162 * Invoking guix lint:: Finding errors in package definitions.
163 * Invoking guix size:: Profiling disk usage.
164 * Invoking guix graph:: Visualizing the graph of packages.
165 * Invoking guix environment:: Setting up development environments.
166 * Invoking guix publish:: Sharing substitutes.
167 * Invoking guix challenge:: Challenging substitute servers.
168 * Invoking guix container:: Process isolation.
170 Invoking @command{guix build}
172 * Common Build Options:: Build options for most commands.
173 * Package Transformation Options:: Creating variants of packages.
174 * Additional Build Options:: Options specific to 'guix build'.
178 * System Installation:: Installing the whole operating system.
179 * System Configuration:: Configuring the operating system.
180 * Installing Debugging Files:: Feeding the debugger.
181 * Security Updates:: Deploying security fixes quickly.
182 * Package Modules:: Packages from the programmer's viewpoint.
183 * Packaging Guidelines:: Growing the distribution.
184 * Bootstrapping:: GNU/Linux built from scratch.
185 * Porting:: Targeting another platform or kernel.
189 * Limitations:: What you can expect.
190 * Hardware Considerations:: Supported hardware.
191 * USB Stick Installation:: Preparing the installation medium.
192 * Preparing for Installation:: Networking, partitioning, etc.
193 * Proceeding with the Installation:: The real thing.
194 * Installing GuixSD in a VM:: GuixSD playground.
195 * Building the Installation Image:: How this comes to be.
199 * Using the Configuration System:: Customizing your GNU system.
200 * operating-system Reference:: Detail of operating-system declarations.
201 * File Systems:: Configuring file system mounts.
202 * Mapped Devices:: Block device extra processing.
203 * User Accounts:: Specifying user accounts.
204 * Locales:: Language and cultural convention settings.
205 * Services:: Specifying system services.
206 * Setuid Programs:: Programs running with root privileges.
207 * X.509 Certificates:: Authenticating HTTPS servers.
208 * Name Service Switch:: Configuring libc's name service switch.
209 * Initial RAM Disk:: Linux-Libre bootstrapping.
210 * GRUB Configuration:: Configuring the boot loader.
211 * Invoking guix system:: Instantiating a system configuration.
212 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
213 * Defining Services:: Adding new service definitions.
217 * Base Services:: Essential system services.
218 * Scheduled Job Execution:: The mcron service.
219 * Log Rotation:: The rottlog service.
220 * Networking Services:: Network setup, SSH daemon, etc.
221 * X Window:: Graphical display.
222 * Desktop Services:: D-Bus and desktop services.
223 * Database Services:: SQL databases.
224 * Mail Services:: IMAP, POP3, SMTP, and all that.
225 * Kerberos Services:: Kerberos services.
226 * Web Services:: Web servers.
227 * Network File System:: NFS related services.
228 * Miscellaneous Services:: Other services.
232 * Service Composition:: The model for composing services.
233 * Service Types and Services:: Types and services.
234 * Service Reference:: API reference.
235 * Shepherd Services:: A particular type of service.
239 * Software Freedom:: What may go into the distribution.
240 * Package Naming:: What's in a name?
241 * Version Numbers:: When the name is not enough.
242 * Synopses and Descriptions:: Helping users find the right package.
243 * Python Modules:: Taming the snake.
244 * Perl Modules:: Little pearls.
245 * Java Packages:: Coffee break.
246 * Fonts:: Fond of fonts.
250 * Building from Git:: The latest and greatest.
251 * Running Guix Before It Is Installed:: Hacker tricks.
252 * The Perfect Setup:: The right tools.
253 * Coding Style:: Hygiene of the contributor.
254 * Submitting Patches:: Share your work.
258 * Programming Paradigm:: How to compose your elements.
259 * Modules:: Where to store your code?
260 * Data Types and Pattern Matching:: Implementing data structures.
261 * Formatting Code:: Writing conventions.
266 @c *********************************************************************
268 @chapter Introduction
271 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
272 using the international phonetic alphabet (IPA).} is a package
273 management tool for the GNU system. Guix makes it easy for unprivileged
274 users to install, upgrade, or remove packages, to roll back to a
275 previous package set, to build packages from source, and generally
276 assists with the creation and maintenance of software environments.
278 @cindex user interfaces
279 Guix provides a command-line package management interface
280 (@pxref{Invoking guix package}), a set of command-line utilities
281 (@pxref{Utilities}), a visual user interface in Emacs (@pxref{Emacs
282 Interface}), as well as Scheme programming interfaces
283 (@pxref{Programming Interface}).
285 Its @dfn{build daemon} is responsible for building packages on behalf of
286 users (@pxref{Setting Up the Daemon}) and for downloading pre-built
287 binaries from authorized sources (@pxref{Substitutes}).
289 @cindex extensibility of the distribution
290 @cindex customization, of packages
291 Guix includes package definitions for many GNU and non-GNU packages, all
292 of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the
293 user's computing freedom}. It is @emph{extensible}: users can write
294 their own package definitions (@pxref{Defining Packages}) and make them
295 available as independent package modules (@pxref{Package Modules}). It
296 is also @emph{customizable}: users can @emph{derive} specialized package
297 definitions from existing ones, including from the command line
298 (@pxref{Package Transformation Options}).
300 @cindex Guix System Distribution
302 You can install GNU@tie{}Guix on top of an existing GNU/Linux system
303 where it complements the available tools without interference
304 (@pxref{Installation}), or you can use it as part of the standalone
305 @dfn{Guix System Distribution} or GuixSD (@pxref{GNU Distribution}).
306 With GNU@tie{}GuixSD, you @emph{declare} all aspects of the operating
307 system configuration and Guix takes care of instantiating the
308 configuration in a transactional, reproducible, and stateless fashion
309 (@pxref{System Configuration}).
311 @cindex functional package management
312 Under the hood, Guix implements the @dfn{functional package management}
313 discipline pioneered by Nix (@pxref{Acknowledgments}).
314 In Guix, the package build and installation process is seen
315 as a @emph{function}, in the mathematical sense. That function takes inputs,
316 such as build scripts, a compiler, and libraries, and
317 returns an installed package. As a pure function, its result depends
318 solely on its inputs---for instance, it cannot refer to software or
319 scripts that were not explicitly passed as inputs. A build function
320 always produces the same result when passed a given set of inputs. It
321 cannot alter the environment of the running system in
322 any way; for instance, it cannot create, modify, or delete files outside
323 of its build and installation directories. This is achieved by running
324 build processes in isolated environments (or @dfn{containers}), where only their
325 explicit inputs are visible.
328 The result of package build functions is @dfn{cached} in the file
329 system, in a special directory called @dfn{the store} (@pxref{The
330 Store}). Each package is installed in a directory of its own in the
331 store---by default under @file{/gnu/store}. The directory name contains
332 a hash of all the inputs used to build that package; thus, changing an
333 input yields a different directory name.
335 This approach is the foundation for the salient features of Guix: support
336 for transactional package upgrade and rollback, per-user installation, and
337 garbage collection of packages (@pxref{Features}).
340 @c *********************************************************************
342 @chapter Installation
344 @cindex installing Guix
345 GNU Guix is available for download from its website at
346 @url{http://www.gnu.org/software/guix/}. This section describes the
347 software requirements of Guix, as well as how to install it and get
350 Note that this section is concerned with the installation of the package
351 manager, which can be done on top of a running GNU/Linux system. If,
352 instead, you want to install the complete GNU operating system,
353 @pxref{System Installation}.
355 @cindex foreign distro
356 When installed on a running GNU/Linux system---thereafter called a
357 @dfn{foreign distro}---GNU@tie{}Guix complements the available tools
358 without interference. Its data lives exclusively in two directories,
359 usually @file{/gnu/store} and @file{/var/guix}; other files on your
360 system, such as @file{/etc}, are left untouched.
362 Once installed, Guix can be updated by running @command{guix pull}
363 (@pxref{Invoking guix pull}).
366 * Binary Installation:: Getting Guix running in no time!
367 * Requirements:: Software needed to build and run Guix.
368 * Running the Test Suite:: Testing Guix.
369 * Setting Up the Daemon:: Preparing the build daemon's environment.
370 * Invoking guix-daemon:: Running the build daemon.
371 * Application Setup:: Application-specific setup.
374 @node Binary Installation
375 @section Binary Installation
377 @cindex installing Guix from binaries
378 This section describes how to install Guix on an arbitrary system from a
379 self-contained tarball providing binaries for Guix and for all its
380 dependencies. This is often quicker than installing from source, which
381 is described in the next sections. The only requirement is to have
384 Installing goes along these lines:
388 @cindex downloading Guix binary
389 Download the binary tarball from
390 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
391 where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
392 already running the kernel Linux, and so on.
394 @c The following is somewhat duplicated in ``System Installation''.
395 Make sure to download the associated @file{.sig} file and to verify the
396 authenticity of the tarball against it, along these lines:
399 $ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
400 $ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
403 If that command fails because you do not have the required public key,
404 then run this command to import it:
407 $ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
411 and rerun the @code{gpg --verify} command.
412 @c end authentication part
419 # tar --warning=no-timestamp -xf \
420 guix-binary-@value{VERSION}.@var{system}.tar.xz
421 # mv var/guix /var/ && mv gnu /
424 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
425 The latter contains a ready-to-use profile for @code{root} (see next
428 Do @emph{not} unpack the tarball on a working Guix system since that
429 would overwrite its own essential files.
431 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
432 not emit warnings about ``implausibly old time stamps'' (such
433 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
435 They stem from the fact that all the
436 files in the archive have their modification time set to zero (which
437 means January 1st, 1970.) This is done on purpose to make sure the
438 archive content is independent of its creation time, thus making it
442 Make @code{root}'s profile available under @file{~/.guix-profile}:
445 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
450 Create the group and user accounts for build users as explained below
451 (@pxref{Build Environment Setup}).
454 Run the daemon, and set it to automatically start on boot.
456 If your host distro uses the systemd init system, this can be achieved
460 # ln -s ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
462 # systemctl start guix-daemon && systemctl enable guix-daemon
465 If your host distro uses the Upstart init system:
468 # ln -s ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
472 Otherwise, you can still start the daemon manually with:
475 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
479 Make the @command{guix} command available to other users on the machine,
483 # mkdir -p /usr/local/bin
485 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
488 It is also a good idea to make the Info version of this manual available
492 # mkdir -p /usr/local/share/info
493 # cd /usr/local/share/info
494 # for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
498 That way, assuming @file{/usr/local/share/info} is in the search path,
499 running @command{info guix} will open this manual (@pxref{Other Info
500 Directories,,, texinfo, GNU Texinfo}, for more details on changing the
504 @cindex substitutes, authorization thereof
505 To use substitutes from @code{hydra.gnu.org} or one of its mirrors
506 (@pxref{Substitutes}), authorize them:
509 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
513 This completes root-level install of Guix. Each user will need to
514 perform additional steps to make their Guix environment ready for use,
515 @pxref{Application Setup}.
517 You can confirm that Guix is working by installing a sample package into
521 # guix package -i hello
524 The @code{guix} package must remain available in @code{root}'s profile,
525 or it would become subject to garbage collection---in which case you
526 would find yourself badly handicapped by the lack of the @command{guix}
527 command. In other words, do not remove @code{guix} by running
528 @code{guix package -r guix}.
530 The binary installation tarball can be (re)produced and verified simply
531 by running the following command in the Guix source tree:
534 make guix-binary.@var{system}.tar.xz
539 @section Requirements
541 This section lists requirements when building Guix from source. The
542 build procedure for Guix is the same as for other GNU software, and is
543 not covered here. Please see the files @file{README} and @file{INSTALL}
544 in the Guix source tree for additional details.
546 GNU Guix depends on the following packages:
549 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
550 @item @url{http://gnupg.org/, GNU libgcrypt};
551 @item @url{http://www.gnu.org/software/make/, GNU Make}.
554 The following dependencies are optional:
558 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will allow you to
559 access @code{https} URLs for substitutes, which is highly recommended
560 (@pxref{Substitutes}). It also allows you to access HTTPS URLs with the
561 @command{guix download} command (@pxref{Invoking guix download}), the
562 @command{guix import pypi} command, and the @command{guix import cpan}
563 command. @xref{Guile Preparations, how to install the GnuTLS bindings
564 for Guile,, gnutls-guile, GnuTLS-Guile}.
568 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
569 allow you to use the @command{guix import pypi} command (@pxref{Invoking
570 guix import}). It is of
571 interest primarily for developers and not for casual users.
574 @c Note: We need at least 0.10.2 for 'channel-send-eof'.
575 Support for build offloading (@pxref{Daemon Offload Setup}) depends on
576 @uref{https://github.com/artyom-poptsov/guile-ssh, Guile-SSH},
577 version 0.10.2 or later.
580 When @url{http://zlib.net, zlib} is available, @command{guix publish}
581 can compress build byproducts (@pxref{Invoking guix publish}).
584 Unless @code{--disable-daemon} was passed to @command{configure}, the
585 following packages are also needed:
588 @item @url{http://sqlite.org, SQLite 3};
589 @item @url{http://www.bzip.org, libbz2};
590 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
594 @cindex state directory
595 When configuring Guix on a system that already has a Guix installation,
596 be sure to specify the same state directory as the existing installation
597 using the @code{--localstatedir} option of the @command{configure}
598 script (@pxref{Directory Variables, @code{localstatedir},, standards,
599 GNU Coding Standards}). The @command{configure} script protects against
600 unintended misconfiguration of @var{localstatedir} so you do not
601 inadvertently corrupt your store (@pxref{The Store}).
603 @cindex Nix, compatibility
604 When a working installation of @url{http://nixos.org/nix/, the Nix package
605 manager} is available, you
606 can instead configure Guix with @code{--disable-daemon}. In that case,
607 Nix replaces the three dependencies above.
609 Guix is compatible with Nix, so it is possible to share the same store
610 between both. To do so, you must pass @command{configure} not only the
611 same @code{--with-store-dir} value, but also the same
612 @code{--localstatedir} value. The latter is essential because it
613 specifies where the database that stores metadata about the store is
614 located, among other things. The default values for Nix are
615 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
616 Note that @code{--disable-daemon} is not required if
617 your goal is to share the store with Nix.
619 @node Running the Test Suite
620 @section Running the Test Suite
623 After a successful @command{configure} and @code{make} run, it is a good
624 idea to run the test suite. It can help catch issues with the setup or
625 environment, or bugs in Guix itself---and really, reporting test
626 failures is a good way to help improve the software. To run the test
633 Test cases can run in parallel: you can use the @code{-j} option of
634 GNU@tie{}make to speed things up. The first run may take a few minutes
635 on a recent machine; subsequent runs will be faster because the store
636 that is created for test purposes will already have various things in
639 It is also possible to run a subset of the tests by defining the
640 @code{TESTS} makefile variable as in this example:
643 make check TESTS="tests/store.scm tests/cpio.scm"
646 By default, tests results are displayed at a file level. In order to
647 see the details of every individual test cases, it is possible to define
648 the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:
651 make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
654 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
655 @file{test-suite.log} file. Please specify the Guix version being used
656 as well as version numbers of the dependencies (@pxref{Requirements}) in
659 Guix also comes with a whole-system test suite that tests complete
660 GuixSD operating system instances. It can only run on systems where
661 Guix is already installed, using:
668 or, again, by defining @code{TESTS} to select a subset of tests to run:
671 make check-system TESTS="basic mcron"
674 These system tests are defined in the @code{(gnu tests @dots{})}
675 modules. They work by running the operating systems under test with
676 lightweight instrumentation in a virtual machine (VM). They can be
677 computationally intensive or rather cheap, depending on whether
678 substitutes are available for their dependencies (@pxref{Substitutes}).
679 Some of them require a lot of storage space to hold VM images.
681 Again in case of test failures, please send @email{bug-guix@@gnu.org}
684 @node Setting Up the Daemon
685 @section Setting Up the Daemon
688 Operations such as building a package or running the garbage collector
689 are all performed by a specialized process, the @dfn{build daemon}, on
690 behalf of clients. Only the daemon may access the store and its
691 associated database. Thus, any operation that manipulates the store
692 goes through the daemon. For instance, command-line tools such as
693 @command{guix package} and @command{guix build} communicate with the
694 daemon (@i{via} remote procedure calls) to instruct it what to do.
696 The following sections explain how to prepare the build daemon's
697 environment. See also @ref{Substitutes}, for information on how to allow
698 the daemon to download pre-built binaries.
701 * Build Environment Setup:: Preparing the isolated build environment.
702 * Daemon Offload Setup:: Offloading builds to remote machines.
705 @node Build Environment Setup
706 @subsection Build Environment Setup
708 @cindex build environment
709 In a standard multi-user setup, Guix and its daemon---the
710 @command{guix-daemon} program---are installed by the system
711 administrator; @file{/gnu/store} is owned by @code{root} and
712 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
713 Guix tools to build packages or otherwise access the store, and the
714 daemon will do it on their behalf, ensuring that the store is kept in a
715 consistent state, and allowing built packages to be shared among users.
718 When @command{guix-daemon} runs as @code{root}, you may not want package
719 build processes themselves to run as @code{root} too, for obvious
720 security reasons. To avoid that, a special pool of @dfn{build users}
721 should be created for use by build processes started by the daemon.
722 These build users need not have a shell and a home directory: they will
723 just be used when the daemon drops @code{root} privileges in build
724 processes. Having several such users allows the daemon to launch
725 distinct build processes under separate UIDs, which guarantees that they
726 do not interfere with each other---an essential feature since builds are
727 regarded as pure functions (@pxref{Introduction}).
729 On a GNU/Linux system, a build user pool may be created like this (using
730 Bash syntax and the @code{shadow} commands):
732 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
733 @c for why `-G' is needed.
735 # groupadd --system guixbuild
736 # for i in `seq -w 1 10`;
738 useradd -g guixbuild -G guixbuild \
739 -d /var/empty -s `which nologin` \
740 -c "Guix build user $i" --system \
746 The number of build users determines how many build jobs may run in
747 parallel, as specified by the @option{--max-jobs} option
748 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). To use
749 @command{guix system vm} and related commands, you may need to add the
750 build users to the @code{kvm} group so they can access @file{/dev/kvm},
751 using @code{-G guixbuild,kvm} instead of @code{-G guixbuild}
752 (@pxref{Invoking guix system}).
754 The @code{guix-daemon} program may then be run as @code{root} with the
755 following command@footnote{If your machine uses the systemd init system,
756 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
757 file in @file{/etc/systemd/system} will ensure that
758 @command{guix-daemon} is automatically started. Similarly, if your
759 machine uses the Upstart init system, drop the
760 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
761 file in @file{/etc/init}.}:
764 # guix-daemon --build-users-group=guixbuild
769 This way, the daemon starts build processes in a chroot, under one of
770 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
771 environment contains nothing but:
773 @c Keep this list in sync with libstore/build.cc! -----------------------
776 a minimal @code{/dev} directory, created mostly independently from the
777 host @code{/dev}@footnote{``Mostly'', because while the set of files
778 that appear in the chroot's @code{/dev} is fixed, most of these files
779 can only be created if the host has them.};
782 the @code{/proc} directory; it only shows the processes of the container
783 since a separate PID name space is used;
786 @file{/etc/passwd} with an entry for the current user and an entry for
790 @file{/etc/group} with an entry for the user's group;
793 @file{/etc/hosts} with an entry that maps @code{localhost} to
797 a writable @file{/tmp} directory.
800 You can influence the directory where the daemon stores build trees
801 @i{via} the @code{TMPDIR} environment variable. However, the build tree
802 within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
803 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
804 This way, the value of @code{TMPDIR} does not leak inside build
805 environments, which avoids discrepancies in cases where build processes
806 capture the name of their build tree.
809 The daemon also honors the @code{http_proxy} environment variable for
810 HTTP downloads it performs, be it for fixed-output derivations
811 (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
813 If you are installing Guix as an unprivileged user, it is still possible
814 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
815 However, build processes will not be isolated from one another, and not
816 from the rest of the system. Thus, build processes may interfere with
817 each other, and may access programs, libraries, and other files
818 available on the system---making it much harder to view them as
819 @emph{pure} functions.
822 @node Daemon Offload Setup
823 @subsection Using the Offload Facility
827 When desired, the build daemon can @dfn{offload} derivation builds to
828 other machines running Guix, using the @code{offload} @dfn{build
829 hook}@footnote{This feature is available only when
830 @uref{https://github.com/artyom-poptsov/guile-ssh, Guile-SSH} is
832 feature is enabled, a list of user-specified build machines is read from
833 @file{/etc/guix/machines.scm}; every time a build is requested, for
834 instance via @code{guix build}, the daemon attempts to offload it to one
835 of the machines that satisfy the constraints of the derivation, in
836 particular its system type---e.g., @file{x86_64-linux}. Missing
837 prerequisites for the build are copied over SSH to the target machine,
838 which then proceeds with the build; upon success the output(s) of the
839 build are copied back to the initial machine.
841 The @file{/etc/guix/machines.scm} file typically looks like this:
845 (name "eightysix.example.org")
846 (system "x86_64-linux")
847 (host-key "ssh-ed25519 AAAAC3Nza@dots{}")
849 (speed 2.)) ;incredibly fast!
852 (name "meeps.example.org")
853 (system "mips64el-linux")
854 (host-key "ssh-rsa AAAAB3Nza@dots{}")
857 (string-append (getenv "HOME")
858 "/.ssh/identity-for-guix"))))
862 In the example above we specify a list of two build machines, one for
863 the @code{x86_64} architecture and one for the @code{mips64el}
866 In fact, this file is---not surprisingly!---a Scheme file that is
867 evaluated when the @code{offload} hook is started. Its return value
868 must be a list of @code{build-machine} objects. While this example
869 shows a fixed list of build machines, one could imagine, say, using
870 DNS-SD to return a list of potential build machines discovered in the
871 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
872 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
875 @deftp {Data Type} build-machine
876 This data type represents build machines to which the daemon may offload
877 builds. The important fields are:
882 The host name of the remote machine.
885 The system type of the remote machine---e.g., @code{"x86_64-linux"}.
888 The user account to use when connecting to the remote machine over SSH.
889 Note that the SSH key pair must @emph{not} be passphrase-protected, to
890 allow non-interactive logins.
893 This must be the machine's SSH @dfn{public host key} in OpenSSH format.
894 This is used to authenticate the machine when we connect to it. It is a
895 long string that looks like this:
898 ssh-ed25519 AAAAC3NzaC@dots{}mde+UhL hint@@example.org
901 If the machine is running the OpenSSH daemon, @command{sshd}, the host
902 key can be found in a file such as
903 @file{/etc/ssh/ssh_host_ed25519_key.pub}.
905 If the machine is running the SSH daemon of GNU@tie{}lsh,
906 @command{lshd}, the host key is in @file{/etc/lsh/host-key.pub} or a
907 similar file. It can be converted to the OpenSSH format using
908 @command{lsh-export-key} (@pxref{Converting keys,,, lsh, LSH Manual}):
911 $ lsh-export-key --openssh < /etc/lsh/host-key.pub
912 ssh-rsa AAAAB3NzaC1yc2EAAAAEOp8FoQAAAQEAs1eB46LV@dots{}
917 A number of optional fields may be specified:
921 @item @code{port} (default: @code{22})
922 Port number of SSH server on the machine.
924 @item @code{private-key} (default: @file{~/.ssh/id_rsa})
925 The SSH private key file to use when connecting to the machine, in
928 @item @code{compression} (default: @code{"zlib@@openssh.com,zlib"})
929 @itemx @code{compression-level} (default: @code{3})
930 The SSH-level compression methods and compression level requested.
932 Note that offloading relies on SSH compression to reduce bandwidth usage
933 when transferring files to and from build machines.
935 @item @code{daemon-socket} (default: @code{"/var/guix/daemon-socket/socket"})
936 File name of the Unix-domain socket @command{guix-daemon} is listening
939 @item @code{parallel-builds} (default: @code{1})
940 The number of builds that may run in parallel on the machine.
942 @item @code{speed} (default: @code{1.0})
943 A ``relative speed factor''. The offload scheduler will tend to prefer
944 machines with a higher speed factor.
946 @item @code{features} (default: @code{'()})
947 A list of strings denoting specific features supported by the machine.
948 An example is @code{"kvm"} for machines that have the KVM Linux modules
949 and corresponding hardware support. Derivations can request features by
950 name, and they will be scheduled on matching build machines.
955 The @code{guile} command must be in the search path on the build
956 machines. In addition, the Guix modules must be in
957 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
958 this is the case by running:
961 ssh build-machine guile -c "'(use-modules (guix config))'"
964 There is one last thing to do once @file{machines.scm} is in place. As
965 explained above, when offloading, files are transferred back and forth
966 between the machine stores. For this to work, you first need to
967 generate a key pair on each machine to allow the daemon to export signed
968 archives of files from the store (@pxref{Invoking guix archive}):
971 # guix archive --generate-key
975 Each build machine must authorize the key of the master machine so that
976 it accepts store items it receives from the master:
979 # guix archive --authorize < master-public-key.txt
983 Likewise, the master machine must authorize the key of each build machine.
985 All the fuss with keys is here to express pairwise mutual trust
986 relations between the master and the build machines. Concretely, when
987 the master receives files from a build machine (and @i{vice versa}), its
988 build daemon can make sure they are genuine, have not been tampered
989 with, and that they are signed by an authorized key.
992 To test whether your setup is operational, run this command on the
999 This will attempt to connect to each of the build machines specified in
1000 @file{/etc/guix/machines.scm}, make sure Guile and the Guix modules are
1001 available on each machine, attempt to export to the machine and import
1002 from it, and report any error in the process.
1004 If you want to test a different machine file, just specify it on the
1008 # guix offload test machines-qualif.scm
1011 Last, you can test the subset of the machines whose name matches a
1012 regular expression like this:
1015 # guix offload test machines.scm '\.gnu\.org$'
1018 @node Invoking guix-daemon
1019 @section Invoking @command{guix-daemon}
1021 The @command{guix-daemon} program implements all the functionality to
1022 access the store. This includes launching build processes, running the
1023 garbage collector, querying the availability of a build result, etc. It
1024 is normally run as @code{root} like this:
1027 # guix-daemon --build-users-group=guixbuild
1031 For details on how to set it up, @pxref{Setting Up the Daemon}.
1034 @cindex container, build environment
1035 @cindex build environment
1036 @cindex reproducible builds
1037 By default, @command{guix-daemon} launches build processes under
1038 different UIDs, taken from the build group specified with
1039 @code{--build-users-group}. In addition, each build process is run in a
1040 chroot environment that only contains the subset of the store that the
1041 build process depends on, as specified by its derivation
1042 (@pxref{Programming Interface, derivation}), plus a set of specific
1043 system directories. By default, the latter contains @file{/dev} and
1044 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
1045 @dfn{container}: in addition to having its own file system tree, it has
1046 a separate mount name space, its own PID name space, network name space,
1047 etc. This helps achieve reproducible builds (@pxref{Features}).
1049 When the daemon performs a build on behalf of the user, it creates a
1050 build directory under @file{/tmp} or under the directory specified by
1051 its @code{TMPDIR} environment variable; this directory is shared with
1052 the container for the duration of the build. Be aware that using a
1053 directory other than @file{/tmp} can affect build results---for example,
1054 with a longer directory name, a build process that uses Unix-domain
1055 sockets might hit the name length limitation for @code{sun_path}, which
1056 it would otherwise not hit.
1058 The build directory is automatically deleted upon completion, unless the
1059 build failed and the client specified @option{--keep-failed}
1060 (@pxref{Invoking guix build, @option{--keep-failed}}).
1062 The following command-line options are supported:
1065 @item --build-users-group=@var{group}
1066 Take users from @var{group} to run build processes (@pxref{Setting Up
1067 the Daemon, build users}).
1069 @item --no-substitutes
1071 Do not use substitutes for build products. That is, always build things
1072 locally instead of allowing downloads of pre-built binaries
1073 (@pxref{Substitutes}).
1075 By default substitutes are used, unless the client---such as the
1076 @command{guix package} command---is explicitly invoked with
1077 @code{--no-substitutes}.
1079 When the daemon runs with @code{--no-substitutes}, clients can still
1080 explicitly enable substitution @i{via} the @code{set-build-options}
1081 remote procedure call (@pxref{The Store}).
1083 @item --substitute-urls=@var{urls}
1084 @anchor{daemon-substitute-urls}
1085 Consider @var{urls} the default whitespace-separated list of substitute
1086 source URLs. When this option is omitted,
1087 @indicateurl{https://mirror.hydra.gnu.org https://hydra.gnu.org} is used
1088 (@code{mirror.hydra.gnu.org} is a mirror of @code{hydra.gnu.org}).
1090 This means that substitutes may be downloaded from @var{urls}, as long
1091 as they are signed by a trusted signature (@pxref{Substitutes}).
1094 @item --no-build-hook
1095 Do not use the @dfn{build hook}.
1097 The build hook is a helper program that the daemon can start and to
1098 which it submits build requests. This mechanism is used to offload
1099 builds to other machines (@pxref{Daemon Offload Setup}).
1101 @item --cache-failures
1102 Cache build failures. By default, only successful builds are cached.
1104 When this option is used, @command{guix gc --list-failures} can be used
1105 to query the set of store items marked as failed; @command{guix gc
1106 --clear-failures} removes store items from the set of cached failures.
1107 @xref{Invoking guix gc}.
1109 @item --cores=@var{n}
1111 Use @var{n} CPU cores to build each derivation; @code{0} means as many
1114 The default value is @code{0}, but it may be overridden by clients, such
1115 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
1118 The effect is to define the @code{NIX_BUILD_CORES} environment variable
1119 in the build process, which can then use it to exploit internal
1120 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
1122 @item --max-jobs=@var{n}
1124 Allow at most @var{n} build jobs in parallel. The default value is
1125 @code{1}. Setting it to @code{0} means that no builds will be performed
1126 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
1127 Setup}), or simply fail.
1129 @item --rounds=@var{N}
1130 Build each derivation @var{n} times in a row, and raise an error if
1131 consecutive build results are not bit-for-bit identical. Note that this
1132 setting can be overridden by clients such as @command{guix build}
1133 (@pxref{Invoking guix build}).
1135 When used in conjunction with @option{--keep-failed}, the differing
1136 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
1137 This makes it easy to look for differences between the two results.
1140 Produce debugging output.
1142 This is useful to debug daemon start-up issues, but then it may be
1143 overridden by clients, for example the @code{--verbosity} option of
1144 @command{guix build} (@pxref{Invoking guix build}).
1146 @item --chroot-directory=@var{dir}
1147 Add @var{dir} to the build chroot.
1149 Doing this may change the result of build processes---for instance if
1150 they use optional dependencies found in @var{dir} when it is available,
1151 and not otherwise. For that reason, it is not recommended to do so.
1152 Instead, make sure that each derivation declares all the inputs that it
1155 @item --disable-chroot
1156 Disable chroot builds.
1158 Using this option is not recommended since, again, it would allow build
1159 processes to gain access to undeclared dependencies. It is necessary,
1160 though, when @command{guix-daemon} is running under an unprivileged user
1163 @item --disable-log-compression
1164 Disable compression of the build logs.
1166 Unless @code{--lose-logs} is used, all the build logs are kept in the
1167 @var{localstatedir}. To save space, the daemon automatically compresses
1168 them with bzip2 by default. This option disables that.
1170 @item --disable-deduplication
1171 @cindex deduplication
1172 Disable automatic file ``deduplication'' in the store.
1174 By default, files added to the store are automatically ``deduplicated'':
1175 if a newly added file is identical to another one found in the store,
1176 the daemon makes the new file a hard link to the other file. This can
1177 noticeably reduce disk usage, at the expense of slightly increased
1178 input/output load at the end of a build process. This option disables
1181 @item --gc-keep-outputs[=yes|no]
1182 Tell whether the garbage collector (GC) must keep outputs of live
1185 When set to ``yes'', the GC will keep the outputs of any live derivation
1186 available in the store---the @code{.drv} files. The default is ``no'',
1187 meaning that derivation outputs are kept only if they are GC roots.
1189 @item --gc-keep-derivations[=yes|no]
1190 Tell whether the garbage collector (GC) must keep derivations
1191 corresponding to live outputs.
1193 When set to ``yes'', as is the case by default, the GC keeps
1194 derivations---i.e., @code{.drv} files---as long as at least one of their
1195 outputs is live. This allows users to keep track of the origins of
1196 items in their store. Setting it to ``no'' saves a bit of disk space.
1198 Note that when both @code{--gc-keep-derivations} and
1199 @code{--gc-keep-outputs} are used, the effect is to keep all the build
1200 prerequisites (the sources, compiler, libraries, and other build-time
1201 tools) of live objects in the store, regardless of whether these
1202 prerequisites are live. This is convenient for developers since it
1203 saves rebuilds or downloads.
1205 @item --impersonate-linux-2.6
1206 On Linux-based systems, impersonate Linux 2.6. This means that the
1207 kernel's @code{uname} system call will report 2.6 as the release number.
1209 This might be helpful to build programs that (usually wrongfully) depend
1210 on the kernel version number.
1213 Do not keep build logs. By default they are kept under
1214 @code{@var{localstatedir}/guix/log}.
1216 @item --system=@var{system}
1217 Assume @var{system} as the current system type. By default it is the
1218 architecture/kernel pair found at configure time, such as
1219 @code{x86_64-linux}.
1221 @item --listen=@var{socket}
1222 Listen for connections on @var{socket}, the file name of a Unix-domain
1223 socket. The default socket is
1224 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
1225 useful in exceptional circumstances, such as if you need to run several
1226 daemons on the same machine.
1230 @node Application Setup
1231 @section Application Setup
1233 @cindex foreign distro
1234 When using Guix on top of GNU/Linux distribution other than GuixSD---a
1235 so-called @dfn{foreign distro}---a few additional steps are needed to
1236 get everything in place. Here are some of them.
1240 @anchor{locales-and-locpath}
1241 @cindex locales, when not on GuixSD
1243 @vindex GUIX_LOCPATH
1244 Packages installed @i{via} Guix will not use the locale data of the
1245 host system. Instead, you must first install one of the locale packages
1246 available with Guix and then define the @code{GUIX_LOCPATH} environment
1250 $ guix package -i glibc-locales
1251 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
1254 Note that the @code{glibc-locales} package contains data for all the
1255 locales supported by the GNU@tie{}libc and weighs in at around
1256 110@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but
1257 limited to a few UTF-8 locales.
1259 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
1260 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
1261 Manual}). There are two important differences though:
1265 @code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
1266 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1267 to make sure the programs of the foreign distro will not end up loading
1268 incompatible locale data.
1271 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1272 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1273 should your Guix profile contain a mixture of programs linked against
1274 different libc version, each libc version will only try to load locale
1275 data in the right format.
1278 This is important because the locale data format used by different libc
1279 versions may be incompatible.
1281 @subsection Name Service Switch
1283 @cindex name service switch, glibc
1284 @cindex NSS (name service switch), glibc
1285 @cindex nscd (name service caching daemon)
1286 @cindex name service caching daemon (nscd)
1287 When using Guix on a foreign distro, we @emph{strongly recommend} that
1288 the system run the GNU C library's @dfn{name service cache daemon},
1289 @command{nscd}, which should be listening on the
1290 @file{/var/run/nscd/socket} socket. Failing to do that, applications
1291 installed with Guix may fail to look up host names or user accounts, or
1292 may even crash. The next paragraphs explain why.
1294 @cindex @file{nsswitch.conf}
1295 The GNU C library implements a @dfn{name service switch} (NSS), which is
1296 an extensible mechanism for ``name lookups'' in general: host name
1297 resolution, user accounts, and more (@pxref{Name Service Switch,,, libc,
1298 The GNU C Library Reference Manual}).
1300 @cindex Network information service (NIS)
1301 @cindex NIS (Network information service)
1302 Being extensible, the NSS supports @dfn{plugins}, which provide new name
1303 lookup implementations: for example, the @code{nss-mdns} plugin allow
1304 resolution of @code{.local} host names, the @code{nis} plugin allows
1305 user account lookup using the Network information service (NIS), and so
1306 on. These extra ``lookup services'' are configured system-wide in
1307 @file{/etc/nsswitch.conf}, and all the programs running on the system
1308 honor those settings (@pxref{NSS Configuration File,,, libc, The GNU C
1311 When they perform a name lookup---for instance by calling the
1312 @code{getaddrinfo} function in C---applications first try to connect to
1313 the nscd; on success, nscd performs name lookups on their behalf. If
1314 the nscd is not running, then they perform the name lookup by
1315 themselves, by loading the name lookup services into their own address
1316 space and running it. These name lookup services---the
1317 @file{libnss_*.so} files---are @code{dlopen}'d, but they may come from
1318 the host system's C library, rather than from the C library the
1319 application is linked against (the C library coming from Guix).
1321 And this is where the problem is: if your application is linked against
1322 Guix's C library (say, glibc 2.24) and tries to load NSS plugins from
1323 another C library (say, @code{libnss_mdns.so} for glibc 2.22), it will
1324 likely crash or have its name lookups fail unexpectedly.
1326 Running @command{nscd} on the system, among other advantages, eliminates
1327 this binary incompatibility problem because those @code{libnss_*.so}
1328 files are loaded in the @command{nscd} process, not in applications
1331 @subsection X11 Fonts
1334 The majority of graphical applications use Fontconfig to locate and
1335 load fonts and perform X11-client-side rendering. The @code{fontconfig}
1336 package in Guix looks for fonts in @file{$HOME/.guix-profile}
1337 by default. Thus, to allow graphical applications installed with Guix
1338 to display fonts, you have to install fonts with Guix as well.
1339 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1340 @code{font-gnu-freefont-ttf}.
1342 To display text written in Chinese languages, Japanese, or Korean in
1343 graphical applications, consider installing
1344 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1345 has multiple outputs, one per language family (@pxref{Packages with
1346 Multiple Outputs}). For instance, the following command installs fonts
1347 for Chinese languages:
1350 guix package -i font-adobe-source-han-sans:cn
1353 @cindex @code{xterm}
1354 Older programs such as @command{xterm} do not use Fontconfig and instead
1355 rely on server-side font rendering. Such programs require to specify a
1356 full name of a font using XLFD (X Logical Font Description), like this:
1359 -*-dejavu sans-medium-r-normal-*-*-100-*-*-*-*-*-1
1362 To be able to use such full names for the TrueType fonts installed in
1363 your Guix profile, you need to extend the font path of the X server:
1366 xset +fp ~/.guix-profile/share/fonts/truetype
1369 @cindex @code{xlsfonts}
1370 After that, you can run @code{xlsfonts} (from @code{xlsfonts} package)
1371 to make sure your TrueType fonts are listed there.
1373 @subsection X.509 Certificates
1375 @cindex @code{nss-certs}
1376 The @code{nss-certs} package provides X.509 certificates, which allow
1377 programs to authenticate Web servers accessed over HTTPS.
1379 When using Guix on a foreign distro, you can install this package and
1380 define the relevant environment variables so that packages know where to
1381 look for certificates. @xref{X.509 Certificates}, for detailed
1384 @subsection Emacs Packages
1386 @cindex @code{emacs}
1387 When you install Emacs packages with Guix, the elisp files may be placed
1388 either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
1390 @file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
1391 directory exists because potentially there may exist thousands of Emacs
1392 packages and storing all their files in a single directory may be not
1393 reliable (because of name conflicts). So we think using a separate
1394 directory for each package is a good idea. It is very similar to how
1395 the Emacs package system organizes the file structure (@pxref{Package
1396 Files,,, emacs, The GNU Emacs Manual}).
1398 By default, Emacs (installed with Guix) ``knows'' where these packages
1399 are placed, so you do not need to perform any configuration. If, for
1400 some reason, you want to avoid auto-loading Emacs packages installed
1401 with Guix, you can do so by running Emacs with @code{--no-site-file}
1402 option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
1406 @c *********************************************************************
1407 @node Package Management
1408 @chapter Package Management
1411 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1412 remove software packages, without having to know about their build
1413 procedures or dependencies. Guix also goes beyond this obvious set of
1416 This chapter describes the main features of Guix, as well as the package
1417 management tools it provides. Two user interfaces are provided for
1418 routine package management tasks: A command-line interface described below
1419 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1420 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1423 * Features:: How Guix will make your life brighter.
1424 * Invoking guix package:: Package installation, removal, etc.
1425 * Substitutes:: Downloading pre-built binaries.
1426 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1427 * Invoking guix gc:: Running the garbage collector.
1428 * Invoking guix pull:: Fetching the latest Guix and distribution.
1429 * Invoking guix archive:: Exporting and importing store files.
1435 When using Guix, each package ends up in the @dfn{package store}, in its
1436 own directory---something that resembles
1437 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1438 (note that Guix comes with an Emacs extension to shorten those file
1439 names, @pxref{Emacs Prettify}.)
1441 Instead of referring to these directories, users have their own
1442 @dfn{profile}, which points to the packages that they actually want to
1443 use. These profiles are stored within each user's home directory, at
1444 @code{$HOME/.guix-profile}.
1446 For example, @code{alice} installs GCC 4.7.2. As a result,
1447 @file{/home/alice/.guix-profile/bin/gcc} points to
1448 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1449 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1450 simply continues to point to
1451 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1452 coexist on the same system without any interference.
1454 The @command{guix package} command is the central tool to manage
1455 packages (@pxref{Invoking guix package}). It operates on the per-user
1456 profiles, and can be used @emph{with normal user privileges}.
1458 @cindex transactions
1459 The command provides the obvious install, remove, and upgrade
1460 operations. Each invocation is actually a @emph{transaction}: either
1461 the specified operation succeeds, or nothing happens. Thus, if the
1462 @command{guix package} process is terminated during the transaction,
1463 or if a power outage occurs during the transaction, then the user's
1464 profile remains in its previous state, and remains usable.
1466 In addition, any package transaction may be @emph{rolled back}. So, if,
1467 for example, an upgrade installs a new version of a package that turns
1468 out to have a serious bug, users may roll back to the previous instance
1469 of their profile, which was known to work well. Similarly, the global
1470 system configuration on GuixSD is subject to
1471 transactional upgrades and roll-back
1472 (@pxref{Using the Configuration System}).
1474 All packages in the package store may be @emph{garbage-collected}.
1475 Guix can determine which packages are still referenced by user
1476 profiles, and remove those that are provably no longer referenced
1477 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1478 generations of their profile so that the packages they refer to can be
1481 @cindex reproducibility
1482 @cindex reproducible builds
1483 Finally, Guix takes a @dfn{purely functional} approach to package
1484 management, as described in the introduction (@pxref{Introduction}).
1485 Each @file{/gnu/store} package directory name contains a hash of all the
1486 inputs that were used to build that package---compiler, libraries, build
1487 scripts, etc. This direct correspondence allows users to make sure a
1488 given package installation matches the current state of their
1489 distribution. It also helps maximize @dfn{build reproducibility}:
1490 thanks to the isolated build environments that are used, a given build
1491 is likely to yield bit-identical files when performed on different
1492 machines (@pxref{Invoking guix-daemon, container}).
1495 This foundation allows Guix to support @dfn{transparent binary/source
1496 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1497 available from an external source---a @dfn{substitute}, Guix just
1498 downloads it and unpacks it;
1499 otherwise, it builds the package from source, locally
1500 (@pxref{Substitutes}). Because build results are usually bit-for-bit
1501 reproducible, users do not have to trust servers that provide
1502 substitutes: they can force a local build and @emph{challenge} providers
1503 (@pxref{Invoking guix challenge}).
1505 Control over the build environment is a feature that is also useful for
1506 developers. The @command{guix environment} command allows developers of
1507 a package to quickly set up the right development environment for their
1508 package, without having to manually install the dependencies of the
1509 package into their profile (@pxref{Invoking guix environment}).
1511 @node Invoking guix package
1512 @section Invoking @command{guix package}
1514 @cindex installing packages
1515 @cindex removing packages
1516 @cindex package installation
1517 @cindex package removal
1518 The @command{guix package} command is the tool that allows users to
1519 install, upgrade, and remove packages, as well as rolling back to
1520 previous configurations. It operates only on the user's own profile,
1521 and works with normal user privileges (@pxref{Features}). Its syntax
1525 guix package @var{options}
1527 @cindex transactions
1528 Primarily, @var{options} specifies the operations to be performed during
1529 the transaction. Upon completion, a new profile is created, but
1530 previous @dfn{generations} of the profile remain available, should the user
1533 For example, to remove @code{lua} and install @code{guile} and
1534 @code{guile-cairo} in a single transaction:
1537 guix package -r lua -i guile guile-cairo
1540 @command{guix package} also supports a @dfn{declarative approach}
1541 whereby the user specifies the exact set of packages to be available and
1542 passes it @i{via} the @option{--manifest} option
1543 (@pxref{profile-manifest, @option{--manifest}}).
1546 For each user, a symlink to the user's default profile is automatically
1547 created in @file{$HOME/.guix-profile}. This symlink always points to the
1548 current generation of the user's default profile. Thus, users can add
1549 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1550 variable, and so on.
1551 @cindex search paths
1552 If you are not using the Guix System Distribution, consider adding the
1553 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1554 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1555 shells get all the right environment variable definitions:
1558 GUIX_PROFILE="$HOME/.guix-profile" \
1559 source "$HOME/.guix-profile/etc/profile"
1562 In a multi-user setup, user profiles are stored in a place registered as
1563 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1564 to (@pxref{Invoking guix gc}). That directory is normally
1565 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1566 @var{localstatedir} is the value passed to @code{configure} as
1567 @code{--localstatedir}, and @var{user} is the user name. The
1568 @file{per-user} directory is created when @command{guix-daemon} is
1569 started, and the @var{user} sub-directory is created by @command{guix
1572 The @var{options} can be among the following:
1576 @item --install=@var{package} @dots{}
1577 @itemx -i @var{package} @dots{}
1578 Install the specified @var{package}s.
1580 Each @var{package} may specify either a simple package name, such as
1581 @code{guile}, or a package name followed by an at-sign and version number,
1582 such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter
1583 case, the newest version prefixed by @code{1.8} is selected.)
1585 If no version number is specified, the
1586 newest available version will be selected. In addition, @var{package}
1587 may contain a colon, followed by the name of one of the outputs of the
1588 package, as in @code{gcc:doc} or @code{binutils@@2.22:lib}
1589 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1590 name (and optionally version) are searched for among the GNU
1591 distribution modules (@pxref{Package Modules}).
1593 @cindex propagated inputs
1594 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1595 that automatically get installed along with the required package
1596 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1597 @code{package} objects}, for information about propagated inputs in
1598 package definitions).
1600 @anchor{package-cmd-propagated-inputs}
1601 An example is the GNU MPC library: its C header files refer to those of
1602 the GNU MPFR library, which in turn refer to those of the GMP library.
1603 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1604 in the profile; removing MPC also removes MPFR and GMP---unless they had
1605 also been explicitly installed by the user.
1607 Besides, packages sometimes rely on the definition of environment
1608 variables for their search paths (see explanation of
1609 @code{--search-paths} below). Any missing or possibly incorrect
1610 environment variable definitions are reported here.
1612 @item --install-from-expression=@var{exp}
1614 Install the package @var{exp} evaluates to.
1616 @var{exp} must be a Scheme expression that evaluates to a
1617 @code{<package>} object. This option is notably useful to disambiguate
1618 between same-named variants of a package, with expressions such as
1619 @code{(@@ (gnu packages base) guile-final)}.
1621 Note that this option installs the first output of the specified
1622 package, which may be insufficient when needing a specific output of a
1623 multiple-output package.
1625 @item --install-from-file=@var{file}
1626 @itemx -f @var{file}
1627 Install the package that the code within @var{file} evaluates to.
1629 As an example, @var{file} might contain a definition like this
1630 (@pxref{Defining Packages}):
1633 @verbatiminclude package-hello.scm
1636 Developers may find it useful to include such a @file{guix.scm} file
1637 in the root of their project source tree that can be used to test
1638 development snapshots and create reproducible development environments
1639 (@pxref{Invoking guix environment}).
1641 @item --remove=@var{package} @dots{}
1642 @itemx -r @var{package} @dots{}
1643 Remove the specified @var{package}s.
1645 As for @code{--install}, each @var{package} may specify a version number
1646 and/or output name in addition to the package name. For instance,
1647 @code{-r glibc:debug} would remove the @code{debug} output of
1650 @item --upgrade[=@var{regexp} @dots{}]
1651 @itemx -u [@var{regexp} @dots{}]
1652 @cindex upgrading packages
1653 Upgrade all the installed packages. If one or more @var{regexp}s are
1654 specified, upgrade only installed packages whose name matches a
1655 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1657 Note that this upgrades package to the latest version of packages found
1658 in the distribution currently installed. To update your distribution,
1659 you should regularly run @command{guix pull} (@pxref{Invoking guix
1662 @item --do-not-upgrade[=@var{regexp} @dots{}]
1663 When used together with the @code{--upgrade} option, do @emph{not}
1664 upgrade any packages whose name matches a @var{regexp}. For example, to
1665 upgrade all packages in the current profile except those containing the
1666 substring ``emacs'':
1669 $ guix package --upgrade . --do-not-upgrade emacs
1672 @item @anchor{profile-manifest}--manifest=@var{file}
1673 @itemx -m @var{file}
1674 @cindex profile declaration
1675 @cindex profile manifest
1676 Create a new generation of the profile from the manifest object
1677 returned by the Scheme code in @var{file}.
1679 This allows you to @emph{declare} the profile's contents rather than
1680 constructing it through a sequence of @code{--install} and similar
1681 commands. The advantage is that @var{file} can be put under version
1682 control, copied to different machines to reproduce the same profile, and
1685 @c FIXME: Add reference to (guix profile) documentation when available.
1686 @var{file} must return a @dfn{manifest} object, which is roughly a list
1689 @findex packages->manifest
1691 (use-package-modules guile emacs)
1696 ;; Use a specific package output.
1697 (list guile-2.0 "debug")))
1701 @cindex rolling back
1702 @cindex undoing transactions
1703 @cindex transactions, undoing
1704 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1705 the last transaction.
1707 When combined with options such as @code{--install}, roll back occurs
1708 before any other actions.
1710 When rolling back from the first generation that actually contains
1711 installed packages, the profile is made to point to the @dfn{zeroth
1712 generation}, which contains no files apart from its own metadata.
1714 After having rolled back, installing, removing, or upgrading packages
1715 overwrites previous future generations. Thus, the history of the
1716 generations in a profile is always linear.
1718 @item --switch-generation=@var{pattern}
1719 @itemx -S @var{pattern}
1721 Switch to a particular generation defined by @var{pattern}.
1723 @var{pattern} may be either a generation number or a number prefixed
1724 with ``+'' or ``-''. The latter means: move forward/backward by a
1725 specified number of generations. For example, if you want to return to
1726 the latest generation after @code{--roll-back}, use
1727 @code{--switch-generation=+1}.
1729 The difference between @code{--roll-back} and
1730 @code{--switch-generation=-1} is that @code{--switch-generation} will
1731 not make a zeroth generation, so if a specified generation does not
1732 exist, the current generation will not be changed.
1734 @item --search-paths[=@var{kind}]
1735 @cindex search paths
1736 Report environment variable definitions, in Bash syntax, that may be
1737 needed in order to use the set of installed packages. These environment
1738 variables are used to specify @dfn{search paths} for files used by some
1739 of the installed packages.
1741 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1742 environment variables to be defined so it can look for headers and
1743 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1744 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1745 library are installed in the profile, then @code{--search-paths} will
1746 suggest setting these variables to @code{@var{profile}/include} and
1747 @code{@var{profile}/lib}, respectively.
1749 The typical use case is to define these environment variables in the
1753 $ eval `guix package --search-paths`
1756 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1757 meaning that the returned environment variable definitions will either
1758 be exact settings, or prefixes or suffixes of the current value of these
1759 variables. When omitted, @var{kind} defaults to @code{exact}.
1761 This option can also be used to compute the @emph{combined} search paths
1762 of several profiles. Consider this example:
1765 $ guix package -p foo -i guile
1766 $ guix package -p bar -i guile-json
1767 $ guix package -p foo -p bar --search-paths
1770 The last command above reports about the @code{GUILE_LOAD_PATH}
1771 variable, even though, taken individually, neither @file{foo} nor
1772 @file{bar} would lead to that recommendation.
1775 @item --profile=@var{profile}
1776 @itemx -p @var{profile}
1777 Use @var{profile} instead of the user's default profile.
1780 Produce verbose output. In particular, emit the build log of the
1781 environment on the standard error port.
1784 Use the bootstrap Guile to build the profile. This option is only
1785 useful to distribution developers.
1789 In addition to these actions, @command{guix package} supports the
1790 following options to query the current state of a profile, or the
1791 availability of packages:
1795 @item --search=@var{regexp}
1796 @itemx -s @var{regexp}
1797 @cindex searching for packages
1798 List the available packages whose name, synopsis, or description matches
1799 @var{regexp}. Print all the metadata of matching packages in
1800 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1801 GNU recutils manual}).
1803 This allows specific fields to be extracted using the @command{recsel}
1804 command, for instance:
1807 $ guix package -s malloc | recsel -p name,version
1815 Similarly, to show the name of all the packages available under the
1816 terms of the GNU@tie{}LGPL version 3:
1819 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1826 It is also possible to refine search results using several @code{-s}
1827 flags. For example, the following command returns a list of board
1831 $ guix package -s '\<board\>' -s game | recsel -p name
1836 If we were to omit @code{-s game}, we would also get software packages
1837 that deal with printed circuit boards; removing the angle brackets
1838 around @code{board} would further add packages that have to do with
1841 And now for a more elaborate example. The following command searches
1842 for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
1843 libraries, and prints the name and synopsis of the matching packages:
1846 $ guix package -s crypto -s library | \
1847 recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
1851 @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
1852 information on @dfn{selection expressions} for @code{recsel -e}.
1854 @item --show=@var{package}
1855 Show details about @var{package}, taken from the list of available packages, in
1856 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1860 $ guix package --show=python | recsel -p name,version
1868 You may also specify the full name of a package to only get details about a
1869 specific version of it:
1871 $ guix package --show=python@@3.4 | recsel -p name,version
1878 @item --list-installed[=@var{regexp}]
1879 @itemx -I [@var{regexp}]
1880 List the currently installed packages in the specified profile, with the
1881 most recently installed packages shown last. When @var{regexp} is
1882 specified, list only installed packages whose name matches @var{regexp}.
1884 For each installed package, print the following items, separated by
1885 tabs: the package name, its version string, the part of the package that
1886 is installed (for instance, @code{out} for the default output,
1887 @code{include} for its headers, etc.), and the path of this package in
1890 @item --list-available[=@var{regexp}]
1891 @itemx -A [@var{regexp}]
1892 List packages currently available in the distribution for this system
1893 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1894 installed packages whose name matches @var{regexp}.
1896 For each package, print the following items separated by tabs: its name,
1897 its version string, the parts of the package (@pxref{Packages with
1898 Multiple Outputs}), and the source location of its definition.
1900 @item --list-generations[=@var{pattern}]
1901 @itemx -l [@var{pattern}]
1903 Return a list of generations along with their creation dates; for each
1904 generation, show the installed packages, with the most recently
1905 installed packages shown last. Note that the zeroth generation is never
1908 For each installed package, print the following items, separated by
1909 tabs: the name of a package, its version string, the part of the package
1910 that is installed (@pxref{Packages with Multiple Outputs}), and the
1911 location of this package in the store.
1913 When @var{pattern} is used, the command returns only matching
1914 generations. Valid patterns include:
1917 @item @emph{Integers and comma-separated integers}. Both patterns denote
1918 generation numbers. For instance, @code{--list-generations=1} returns
1921 And @code{--list-generations=1,8,2} outputs three generations in the
1922 specified order. Neither spaces nor trailing commas are allowed.
1924 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1925 specified generations and everything in between. Note that the start of
1926 a range must be smaller than its end.
1928 It is also possible to omit the endpoint. For example,
1929 @code{--list-generations=2..}, returns all generations starting from the
1932 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1933 or months by passing an integer along with the first letter of the
1934 duration. For example, @code{--list-generations=20d} lists generations
1935 that are up to 20 days old.
1938 @item --delete-generations[=@var{pattern}]
1939 @itemx -d [@var{pattern}]
1940 When @var{pattern} is omitted, delete all generations except the current
1943 This command accepts the same patterns as @option{--list-generations}.
1944 When @var{pattern} is specified, delete the matching generations. When
1945 @var{pattern} specifies a duration, generations @emph{older} than the
1946 specified duration match. For instance, @code{--delete-generations=1m}
1947 deletes generations that are more than one month old.
1949 If the current generation matches, it is @emph{not} deleted. Also, the
1950 zeroth generation is never deleted.
1952 Note that deleting generations prevents rolling back to them.
1953 Consequently, this command must be used with care.
1957 Finally, since @command{guix package} may actually start build
1958 processes, it supports all the common build options (@pxref{Common Build
1959 Options}). It also supports package transformation options, such as
1960 @option{--with-source} (@pxref{Package Transformation Options}).
1961 However, note that package transformations are lost when upgrading; to
1962 preserve transformations across upgrades, you should define your own
1963 package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
1964 (@pxref{Defining Packages}).
1968 @section Substitutes
1971 @cindex pre-built binaries
1972 Guix supports transparent source/binary deployment, which means that it
1973 can either build things locally, or download pre-built items from a
1974 server. We call these pre-built items @dfn{substitutes}---they are
1975 substitutes for local build results. In many cases, downloading a
1976 substitute is much faster than building things locally.
1978 Substitutes can be anything resulting from a derivation build
1979 (@pxref{Derivations}). Of course, in the common case, they are
1980 pre-built package binaries, but source tarballs, for instance, which
1981 also result from derivation builds, can be available as substitutes.
1983 The @code{hydra.gnu.org} server is a front-end to a build farm that
1984 builds packages from the GNU distribution continuously for some
1985 architectures, and makes them available as substitutes (@pxref{Emacs
1986 Hydra}, for information on how to query the continuous integration
1987 server). This is the
1988 default source of substitutes; it can be overridden by passing the
1989 @option{--substitute-urls} option either to @command{guix-daemon}
1990 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1991 or to client tools such as @command{guix package}
1992 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1995 Substitute URLs can be either HTTP or HTTPS@footnote{For HTTPS access,
1996 the Guile bindings of GnuTLS must be installed. @xref{Requirements}.}
1997 HTTPS is recommended because communications are encrypted; conversely,
1998 using HTTP makes all communications visible to an eavesdropper, who
1999 could use the information gathered to determine, for instance, whether
2000 your system has unpatched security vulnerabilities.
2003 @cindex digital signatures
2004 @cindex substitutes, authorization thereof
2005 To allow Guix to download substitutes from @code{hydra.gnu.org} or a
2007 must add its public key to the access control list (ACL) of archive
2008 imports, using the @command{guix archive} command (@pxref{Invoking guix
2009 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
2010 be compromised and to serve genuine substitutes.
2012 This public key is installed along with Guix, in
2013 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
2014 the installation prefix of Guix. If you installed Guix from source,
2015 make sure you checked the GPG signature of
2016 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
2017 Then, you can run something like this:
2020 # guix archive --authorize < hydra.gnu.org.pub
2023 Once this is in place, the output of a command like @code{guix build}
2024 should change from something like:
2027 $ guix build emacs --dry-run
2028 The following derivations would be built:
2029 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
2030 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
2031 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
2032 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
2040 $ guix build emacs --dry-run
2041 The following files would be downloaded:
2042 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
2043 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
2044 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
2045 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
2050 This indicates that substitutes from @code{hydra.gnu.org} are usable and
2051 will be downloaded, when possible, for future builds.
2053 Guix ignores substitutes that are not signed, or that are not signed by
2054 one of the keys listed in the ACL. It also detects and raises an error
2055 when attempting to use a substitute that has been tampered with.
2058 Substitutes are downloaded over HTTP or HTTPS.
2059 The @code{http_proxy} environment
2060 variable can be set in the environment of @command{guix-daemon} and is
2061 honored for downloads of substitutes. Note that the value of
2062 @code{http_proxy} in the environment where @command{guix build},
2063 @command{guix package}, and other client commands are run has
2064 @emph{absolutely no effect}.
2066 When using HTTPS, the server's X.509 certificate is @emph{not} validated
2067 (in other words, the server is not authenticated), contrary to what
2068 HTTPS clients such as Web browsers usually do. This is because Guix
2069 authenticates substitute information itself, as explained above, which
2070 is what we care about (whereas X.509 certificates are about
2071 authenticating bindings between domain names and public keys.)
2073 The substitute mechanism can be disabled globally by running
2074 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
2075 guix-daemon}). It can also be disabled temporarily by passing the
2076 @code{--no-substitutes} option to @command{guix package}, @command{guix
2077 build}, and other command-line tools.
2080 @unnumberedsubsec On Trusting Binaries
2082 Today, each individual's control over their own computing is at the
2083 mercy of institutions, corporations, and groups with enough power and
2084 determination to subvert the computing infrastructure and exploit its
2085 weaknesses. While using @code{hydra.gnu.org} substitutes can be
2086 convenient, we encourage users to also build on their own, or even run
2087 their own build farm, such that @code{hydra.gnu.org} is less of an
2088 interesting target. One way to help is by publishing the software you
2089 build using @command{guix publish} so that others have one more choice
2090 of server to download substitutes from (@pxref{Invoking guix publish}).
2092 Guix has the foundations to maximize build reproducibility
2093 (@pxref{Features}). In most cases, independent builds of a given
2094 package or derivation should yield bit-identical results. Thus, through
2095 a diverse set of independent package builds, we can strengthen the
2096 integrity of our systems. The @command{guix challenge} command aims to
2097 help users assess substitute servers, and to assist developers in
2098 finding out about non-deterministic package builds (@pxref{Invoking guix
2099 challenge}). Similarly, the @option{--check} option of @command{guix
2100 build} allows users to check whether previously-installed substitutes
2101 are genuine by rebuilding them locally (@pxref{build-check,
2102 @command{guix build --check}}).
2104 In the future, we want Guix to have support to publish and retrieve
2105 binaries to/from other users, in a peer-to-peer fashion. If you would
2106 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
2109 @node Packages with Multiple Outputs
2110 @section Packages with Multiple Outputs
2112 @cindex multiple-output packages
2113 @cindex package outputs
2116 Often, packages defined in Guix have a single @dfn{output}---i.e., the
2117 source package leads to exactly one directory in the store. When running
2118 @command{guix package -i glibc}, one installs the default output of the
2119 GNU libc package; the default output is called @code{out}, but its name
2120 can be omitted as shown in this command. In this particular case, the
2121 default output of @code{glibc} contains all the C header files, shared
2122 libraries, static libraries, Info documentation, and other supporting
2125 Sometimes it is more appropriate to separate the various types of files
2126 produced from a single source package into separate outputs. For
2127 instance, the GLib C library (used by GTK+ and related packages)
2128 installs more than 20 MiB of reference documentation as HTML pages.
2129 To save space for users who do not need it, the documentation goes to a
2130 separate output, called @code{doc}. To install the main GLib output,
2131 which contains everything but the documentation, one would run:
2134 guix package -i glib
2137 @cindex documentation
2138 The command to install its documentation is:
2141 guix package -i glib:doc
2144 Some packages install programs with different ``dependency footprints''.
2145 For instance, the WordNet package installs both command-line tools and
2146 graphical user interfaces (GUIs). The former depend solely on the C
2147 library, whereas the latter depend on Tcl/Tk and the underlying X
2148 libraries. In this case, we leave the command-line tools in the default
2149 output, whereas the GUIs are in a separate output. This allows users
2150 who do not need the GUIs to save space. The @command{guix size} command
2151 can help find out about such situations (@pxref{Invoking guix size}).
2152 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
2154 There are several such multiple-output packages in the GNU distribution.
2155 Other conventional output names include @code{lib} for libraries and
2156 possibly header files, @code{bin} for stand-alone programs, and
2157 @code{debug} for debugging information (@pxref{Installing Debugging
2158 Files}). The outputs of a packages are listed in the third column of
2159 the output of @command{guix package --list-available} (@pxref{Invoking
2163 @node Invoking guix gc
2164 @section Invoking @command{guix gc}
2166 @cindex garbage collector
2168 Packages that are installed, but not used, may be @dfn{garbage-collected}.
2169 The @command{guix gc} command allows users to explicitly run the garbage
2170 collector to reclaim space from the @file{/gnu/store} directory. It is
2171 the @emph{only} way to remove files from @file{/gnu/store}---removing
2172 files or directories manually may break it beyond repair!
2174 The garbage collector has a set of known @dfn{roots}: any file under
2175 @file{/gnu/store} reachable from a root is considered @dfn{live} and
2176 cannot be deleted; any other file is considered @dfn{dead} and may be
2177 deleted. The set of garbage collector roots includes default user
2178 profiles, and may be augmented with @command{guix build --root}, for
2179 example (@pxref{Invoking guix build}).
2181 Prior to running @code{guix gc --collect-garbage} to make space, it is
2182 often useful to remove old generations from user profiles; that way, old
2183 package builds referenced by those generations can be reclaimed. This
2184 is achieved by running @code{guix package --delete-generations}
2185 (@pxref{Invoking guix package}).
2187 The @command{guix gc} command has three modes of operation: it can be
2188 used to garbage-collect any dead files (the default), to delete specific
2189 files (the @code{--delete} option), to print garbage-collector
2190 information, or for more advanced queries. The garbage collection
2191 options are as follows:
2194 @item --collect-garbage[=@var{min}]
2195 @itemx -C [@var{min}]
2196 Collect garbage---i.e., unreachable @file{/gnu/store} files and
2197 sub-directories. This is the default operation when no option is
2200 When @var{min} is given, stop once @var{min} bytes have been collected.
2201 @var{min} may be a number of bytes, or it may include a unit as a
2202 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
2203 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
2205 When @var{min} is omitted, collect all the garbage.
2207 @item --free-space=@var{free}
2208 @itemx -F @var{free}
2209 Collect garbage until @var{free} space is available under
2210 @file{/gnu/store}, if possible; @var{free} denotes storage space, such
2211 as @code{500MiB}, as described above.
2213 When @var{free} or more is already available in @file{/gnu/store}, do
2214 nothing and exit immediately.
2218 Attempt to delete all the store files and directories specified as
2219 arguments. This fails if some of the files are not in the store, or if
2220 they are still live.
2222 @item --list-failures
2223 List store items corresponding to cached build failures.
2225 This prints nothing unless the daemon was started with
2226 @option{--cache-failures} (@pxref{Invoking guix-daemon,
2227 @option{--cache-failures}}).
2229 @item --clear-failures
2230 Remove the specified store items from the failed-build cache.
2232 Again, this option only makes sense when the daemon is started with
2233 @option{--cache-failures}. Otherwise, it does nothing.
2236 Show the list of dead files and directories still present in the
2237 store---i.e., files and directories no longer reachable from any root.
2240 Show the list of live store files and directories.
2244 In addition, the references among existing store files can be queried:
2250 @cindex package dependencies
2251 List the references (respectively, the referrers) of store files given
2257 List the requisites of the store files passed as arguments. Requisites
2258 include the store files themselves, their references, and the references
2259 of these, recursively. In other words, the returned list is the
2260 @dfn{transitive closure} of the store files.
2262 @xref{Invoking guix size}, for a tool to profile the size of the closure
2263 of an element. @xref{Invoking guix graph}, for a tool to visualize
2264 the graph of references.
2268 Lastly, the following options allow you to check the integrity of the
2269 store and to control disk usage.
2273 @item --verify[=@var{options}]
2274 @cindex integrity, of the store
2275 @cindex integrity checking
2276 Verify the integrity of the store.
2278 By default, make sure that all the store items marked as valid in the
2279 database of the daemon actually exist in @file{/gnu/store}.
2281 When provided, @var{options} must be a comma-separated list containing one
2282 or more of @code{contents} and @code{repair}.
2284 When passing @option{--verify=contents}, the daemon computes the
2285 content hash of each store item and compares it against its hash in the
2286 database. Hash mismatches are reported as data corruptions. Because it
2287 traverses @emph{all the files in the store}, this command can take a
2288 long time, especially on systems with a slow disk drive.
2290 @cindex repairing the store
2291 Using @option{--verify=repair} or @option{--verify=contents,repair}
2292 causes the daemon to try to repair corrupt store items by fetching
2293 substitutes for them (@pxref{Substitutes}). Because repairing is not
2294 atomic, and thus potentially dangerous, it is available only to the
2295 system administrator.
2298 @cindex deduplication
2299 Optimize the store by hard-linking identical files---this is
2300 @dfn{deduplication}.
2302 The daemon performs deduplication after each successful build or archive
2303 import, unless it was started with @code{--disable-deduplication}
2304 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
2305 this option is primarily useful when the daemon was running with
2306 @code{--disable-deduplication}.
2310 @node Invoking guix pull
2311 @section Invoking @command{guix pull}
2313 @cindex upgrading Guix
2314 @cindex updating Guix
2315 @cindex @command{guix pull}
2317 Packages are installed or upgraded to the latest version available in
2318 the distribution currently available on your local machine. To update
2319 that distribution, along with the Guix tools, you must run @command{guix
2320 pull}: the command downloads the latest Guix source code and package
2321 descriptions, and deploys it.
2323 On completion, @command{guix package} will use packages and package
2324 versions from this just-retrieved copy of Guix. Not only that, but all
2325 the Guix commands and Scheme modules will also be taken from that latest
2326 version. New @command{guix} sub-commands added by the update also
2329 Any user can update their Guix copy using @command{guix pull}, and the
2330 effect is limited to the user who run @command{guix pull}. For
2331 instance, when user @code{root} runs @command{guix pull}, this has no
2332 effect on the version of Guix that user @code{alice} sees, and vice
2333 versa@footnote{Under the hood, @command{guix pull} updates the
2334 @file{~/.config/guix/latest} symbolic link to point to the latest Guix,
2335 and the @command{guix} command loads code from there.}.
2337 The @command{guix pull} command is usually invoked with no arguments,
2338 but it supports the following options:
2342 Produce verbose output, writing build logs to the standard error output.
2344 @item --url=@var{url}
2345 Download the source tarball of Guix from @var{url}.
2347 By default, the tarball is taken from its canonical address at
2348 @code{gnu.org}, for the stable branch of Guix.
2351 Use the bootstrap Guile to build the latest Guix. This option is only
2352 useful to Guix developers.
2356 @node Invoking guix archive
2357 @section Invoking @command{guix archive}
2359 @cindex @command{guix archive}
2361 The @command{guix archive} command allows users to @dfn{export} files
2362 from the store into a single archive, and to later @dfn{import} them.
2363 In particular, it allows store files to be transferred from one machine
2364 to the store on another machine.
2366 @cindex exporting store items
2367 To export store files as an archive to standard output, run:
2370 guix archive --export @var{options} @var{specifications}...
2373 @var{specifications} may be either store file names or package
2374 specifications, as for @command{guix package} (@pxref{Invoking guix
2375 package}). For instance, the following command creates an archive
2376 containing the @code{gui} output of the @code{git} package and the main
2377 output of @code{emacs}:
2380 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2383 If the specified packages are not built yet, @command{guix archive}
2384 automatically builds them. The build process may be controlled with the
2385 common build options (@pxref{Common Build Options}).
2387 To transfer the @code{emacs} package to a machine connected over SSH,
2391 guix archive --export -r emacs | ssh the-machine guix archive --import
2395 Similarly, a complete user profile may be transferred from one machine
2396 to another like this:
2399 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2400 ssh the-machine guix-archive --import
2404 However, note that, in both examples, all of @code{emacs} and the
2405 profile as well as all of their dependencies are transferred (due to
2406 @code{-r}), regardless of what is already available in the store on the
2407 target machine. The @code{--missing} option can help figure out which
2408 items are missing from the target store.
2410 @cindex nar, archive format
2411 @cindex normalized archive (nar)
2412 Archives are stored in the ``normalized archive'' or ``nar'' format, which is
2413 comparable in spirit to `tar', but with differences
2414 that make it more appropriate for our purposes. First, rather than
2415 recording all Unix metadata for each file, the nar format only mentions
2416 the file type (regular, directory, or symbolic link); Unix permissions
2417 and owner/group are dismissed. Second, the order in which directory
2418 entries are stored always follows the order of file names according to
2419 the C locale collation order. This makes archive production fully
2422 When exporting, the daemon digitally signs the contents of the archive,
2423 and that digital signature is appended. When importing, the daemon
2424 verifies the signature and rejects the import in case of an invalid
2425 signature or if the signing key is not authorized.
2426 @c FIXME: Add xref to daemon doc about signatures.
2428 The main options are:
2432 Export the specified store files or packages (see below.) Write the
2433 resulting archive to the standard output.
2435 Dependencies are @emph{not} included in the output, unless
2436 @code{--recursive} is passed.
2440 When combined with @code{--export}, this instructs @command{guix
2441 archive} to include dependencies of the given items in the archive.
2442 Thus, the resulting archive is self-contained: it contains the closure
2443 of the exported store items.
2446 Read an archive from the standard input, and import the files listed
2447 therein into the store. Abort if the archive has an invalid digital
2448 signature, or if it is signed by a public key not among the authorized
2449 keys (see @code{--authorize} below.)
2452 Read a list of store file names from the standard input, one per line,
2453 and write on the standard output the subset of these files missing from
2456 @item --generate-key[=@var{parameters}]
2457 @cindex signing, archives
2458 Generate a new key pair for the daemon. This is a prerequisite before
2459 archives can be exported with @code{--export}. Note that this operation
2460 usually takes time, because it needs to gather enough entropy to
2461 generate the key pair.
2463 The generated key pair is typically stored under @file{/etc/guix}, in
2464 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2465 key, which must be kept secret.) When @var{parameters} is omitted,
2466 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2467 versions before 1.6.0, it is a 4096-bit RSA key.
2468 Alternatively, @var{parameters} can specify
2469 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2470 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2471 Libgcrypt Reference Manual}).
2474 @cindex authorizing, archives
2475 Authorize imports signed by the public key passed on standard input.
2476 The public key must be in ``s-expression advanced format''---i.e., the
2477 same format as the @file{signing-key.pub} file.
2479 The list of authorized keys is kept in the human-editable file
2480 @file{/etc/guix/acl}. The file contains
2481 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2482 s-expressions''} and is structured as an access-control list in the
2483 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2486 @item --extract=@var{directory}
2487 @itemx -x @var{directory}
2488 Read a single-item archive as served by substitute servers
2489 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2490 low-level operation needed in only very narrow use cases; see below.
2492 For example, the following command extracts the substitute for Emacs
2493 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2497 https://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2498 | bunzip2 | guix archive -x /tmp/emacs
2501 Single-item archives are different from multiple-item archives produced
2502 by @command{guix archive --export}; they contain a single store item,
2503 and they do @emph{not} embed a signature. Thus this operation does
2504 @emph{no} signature verification and its output should be considered
2507 The primary purpose of this operation is to facilitate inspection of
2508 archive contents coming from possibly untrusted substitute servers.
2512 @c *********************************************************************
2515 @c *********************************************************************
2516 @node Programming Interface
2517 @chapter Programming Interface
2519 GNU Guix provides several Scheme programming interfaces (APIs) to
2520 define, build, and query packages. The first interface allows users to
2521 write high-level package definitions. These definitions refer to
2522 familiar packaging concepts, such as the name and version of a package,
2523 its build system, and its dependencies. These definitions can then be
2524 turned into concrete build actions.
2526 Build actions are performed by the Guix daemon, on behalf of users. In a
2527 standard setup, the daemon has write access to the store---the
2528 @file{/gnu/store} directory---whereas users do not. The recommended
2529 setup also has the daemon perform builds in chroots, under a specific
2530 build users, to minimize interference with the rest of the system.
2533 Lower-level APIs are available to interact with the daemon and the
2534 store. To instruct the daemon to perform a build action, users actually
2535 provide it with a @dfn{derivation}. A derivation is a low-level
2536 representation of the build actions to be taken, and the environment in
2537 which they should occur---derivations are to package definitions what
2538 assembly is to C programs. The term ``derivation'' comes from the fact
2539 that build results @emph{derive} from them.
2541 This chapter describes all these APIs in turn, starting from high-level
2542 package definitions.
2545 * Defining Packages:: Defining new packages.
2546 * Build Systems:: Specifying how packages are built.
2547 * The Store:: Manipulating the package store.
2548 * Derivations:: Low-level interface to package derivations.
2549 * The Store Monad:: Purely functional interface to the store.
2550 * G-Expressions:: Manipulating build expressions.
2553 @node Defining Packages
2554 @section Defining Packages
2556 The high-level interface to package definitions is implemented in the
2557 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2558 example, the package definition, or @dfn{recipe}, for the GNU Hello
2559 package looks like this:
2562 (define-module (gnu packages hello)
2563 #:use-module (guix packages)
2564 #:use-module (guix download)
2565 #:use-module (guix build-system gnu)
2566 #:use-module (guix licenses)
2567 #:use-module (gnu packages gawk))
2569 (define-public hello
2575 (uri (string-append "mirror://gnu/hello/hello-" version
2579 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2580 (build-system gnu-build-system)
2581 (arguments '(#:configure-flags '("--enable-silent-rules")))
2582 (inputs `(("gawk" ,gawk)))
2583 (synopsis "Hello, GNU world: An example GNU package")
2584 (description "Guess what GNU Hello prints!")
2585 (home-page "http://www.gnu.org/software/hello/")
2590 Without being a Scheme expert, the reader may have guessed the meaning
2591 of the various fields here. This expression binds the variable
2592 @code{hello} to a @code{<package>} object, which is essentially a record
2593 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2594 This package object can be inspected using procedures found in the
2595 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2596 returns---surprise!---@code{"hello"}.
2598 With luck, you may be able to import part or all of the definition of
2599 the package you are interested in from another repository, using the
2600 @code{guix import} command (@pxref{Invoking guix import}).
2602 In the example above, @var{hello} is defined in a module of its own,
2603 @code{(gnu packages hello)}. Technically, this is not strictly
2604 necessary, but it is convenient to do so: all the packages defined in
2605 modules under @code{(gnu packages @dots{})} are automatically known to
2606 the command-line tools (@pxref{Package Modules}).
2608 There are a few points worth noting in the above package definition:
2612 The @code{source} field of the package is an @code{<origin>} object
2613 (@pxref{origin Reference}, for the complete reference).
2614 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2615 meaning that the source is a file to be downloaded over FTP or HTTP.
2617 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2618 the GNU mirrors defined in @code{(guix download)}.
2620 The @code{sha256} field specifies the expected SHA256 hash of the file
2621 being downloaded. It is mandatory, and allows Guix to check the
2622 integrity of the file. The @code{(base32 @dots{})} form introduces the
2623 base32 representation of the hash. You can obtain this information with
2624 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2625 hash} (@pxref{Invoking guix hash}).
2628 When needed, the @code{origin} form can also have a @code{patches} field
2629 listing patches to be applied, and a @code{snippet} field giving a
2630 Scheme expression to modify the source code.
2633 @cindex GNU Build System
2634 The @code{build-system} field specifies the procedure to build the
2635 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2636 represents the familiar GNU Build System, where packages may be
2637 configured, built, and installed with the usual @code{./configure &&
2638 make && make check && make install} command sequence.
2641 The @code{arguments} field specifies options for the build system
2642 (@pxref{Build Systems}). Here it is interpreted by
2643 @var{gnu-build-system} as a request run @file{configure} with the
2644 @code{--enable-silent-rules} flag.
2650 What about these quote (@code{'}) characters? They are Scheme syntax to
2651 introduce a literal list; @code{'} is synonymous with @code{quote}.
2652 @xref{Expression Syntax, quoting,, guile, GNU Guile Reference Manual},
2653 for details. Here the value of the @code{arguments} field is a list of
2654 arguments passed to the build system down the road, as with @code{apply}
2655 (@pxref{Fly Evaluation, @code{apply},, guile, GNU Guile Reference
2658 The hash-colon (@code{#:}) sequence defines a Scheme @dfn{keyword}
2659 (@pxref{Keywords,,, guile, GNU Guile Reference Manual}), and
2660 @code{#:configure-flags} is a keyword used to pass a keyword argument
2661 to the build system (@pxref{Coding With Keywords,,, guile, GNU Guile
2665 The @code{inputs} field specifies inputs to the build process---i.e.,
2666 build-time or run-time dependencies of the package. Here, we define an
2667 input called @code{"gawk"} whose value is that of the @var{gawk}
2668 variable; @var{gawk} is itself bound to a @code{<package>} object.
2670 @cindex backquote (quasiquote)
2673 @cindex comma (unquote)
2677 @findex unquote-splicing
2678 Again, @code{`} (a backquote, synonymous with @code{quasiquote}) allows
2679 us to introduce a literal list in the @code{inputs} field, while
2680 @code{,} (a comma, synonymous with @code{unquote}) allows us to insert a
2681 value in that list (@pxref{Expression Syntax, unquote,, guile, GNU Guile
2684 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2685 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2686 of ensuring that they are present (@pxref{Build Systems}).
2688 However, any other dependencies need to be specified in the
2689 @code{inputs} field. Any dependency not specified here will simply be
2690 unavailable to the build process, possibly leading to a build failure.
2693 @xref{package Reference}, for a full description of possible fields.
2695 Once a package definition is in place, the
2696 package may actually be built using the @code{guix build} command-line
2697 tool (@pxref{Invoking guix build}). You can easily jump back to the
2698 package definition using the @command{guix edit} command
2699 (@pxref{Invoking guix edit}).
2700 @xref{Packaging Guidelines}, for
2701 more information on how to test package definitions, and
2702 @ref{Invoking guix lint}, for information on how to check a definition
2703 for style conformance.
2705 Finally, updating the package definition to a new upstream version
2706 can be partly automated by the @command{guix refresh} command
2707 (@pxref{Invoking guix refresh}).
2709 Behind the scenes, a derivation corresponding to the @code{<package>}
2710 object is first computed by the @code{package-derivation} procedure.
2711 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2712 The build actions it prescribes may then be realized by using the
2713 @code{build-derivations} procedure (@pxref{The Store}).
2715 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2716 Return the @code{<derivation>} object of @var{package} for @var{system}
2717 (@pxref{Derivations}).
2719 @var{package} must be a valid @code{<package>} object, and @var{system}
2720 must be a string denoting the target system type---e.g.,
2721 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2722 must be a connection to the daemon, which operates on the store
2723 (@pxref{The Store}).
2727 @cindex cross-compilation
2728 Similarly, it is possible to compute a derivation that cross-builds a
2729 package for some other system:
2731 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2732 @var{package} @var{target} [@var{system}]
2733 Return the @code{<derivation>} object of @var{package} cross-built from
2734 @var{system} to @var{target}.
2736 @var{target} must be a valid GNU triplet denoting the target hardware
2737 and operating system, such as @code{"mips64el-linux-gnu"}
2738 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2739 Configure and Build System}).
2742 @cindex package transformations
2743 @cindex input rewriting
2744 @cindex dependency tree rewriting
2745 Packages can be manipulated in arbitrary ways. An example of a useful
2746 transformation is @dfn{input rewriting}, whereby the dependency tree of
2747 a package is rewritten by replacing specific inputs by others:
2749 @deffn {Scheme Procedure} package-input-rewriting @var{replacements} @
2750 [@var{rewrite-name}]
2751 Return a procedure that, when passed a package, replaces its direct and
2752 indirect dependencies (but not its implicit inputs) according to
2753 @var{replacements}. @var{replacements} is a list of package pairs; the
2754 first element of each pair is the package to replace, and the second one
2757 Optionally, @var{rewrite-name} is a one-argument procedure that takes
2758 the name of a package and returns its new name after rewrite.
2762 Consider this example:
2765 (define libressl-instead-of-openssl
2766 ;; This is a procedure to replace OPENSSL by LIBRESSL,
2768 (package-input-rewriting `((,openssl . ,libressl))))
2770 (define git-with-libressl
2771 (libressl-instead-of-openssl git))
2775 Here we first define a rewriting procedure that replaces @var{openssl}
2776 with @var{libressl}. Then we use it to define a @dfn{variant} of the
2777 @var{git} package that uses @var{libressl} instead of @var{openssl}.
2778 This is exactly what the @option{--with-input} command-line option does
2779 (@pxref{Package Transformation Options, @option{--with-input}}).
2782 * package Reference :: The package data type.
2783 * origin Reference:: The origin data type.
2787 @node package Reference
2788 @subsection @code{package} Reference
2790 This section summarizes all the options available in @code{package}
2791 declarations (@pxref{Defining Packages}).
2793 @deftp {Data Type} package
2794 This is the data type representing a package recipe.
2798 The name of the package, as a string.
2800 @item @code{version}
2801 The version of the package, as a string.
2804 An object telling how the source code for the package should be
2805 acquired. Most of the time, this is an @code{origin} object, which
2806 denotes a file fetched from the Internet (@pxref{origin Reference}). It
2807 can also be any other ``file-like'' object such as a @code{local-file},
2808 which denotes a file from the local file system (@pxref{G-Expressions,
2809 @code{local-file}}).
2811 @item @code{build-system}
2812 The build system that should be used to build the package (@pxref{Build
2815 @item @code{arguments} (default: @code{'()})
2816 The arguments that should be passed to the build system. This is a
2817 list, typically containing sequential keyword-value pairs.
2819 @item @code{inputs} (default: @code{'()})
2820 @itemx @code{native-inputs} (default: @code{'()})
2821 @itemx @code{propagated-inputs} (default: @code{'()})
2822 @cindex inputs, of packages
2823 These fields list dependencies of the package. Each one is a list of
2824 tuples, where each tuple has a label for the input (a string) as its
2825 first element, a package, origin, or derivation as its second element,
2826 and optionally the name of the output thereof that should be used, which
2827 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2828 more on package outputs). For example, the list below specifies three
2832 `(("libffi" ,libffi)
2833 ("libunistring" ,libunistring)
2834 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2837 @cindex cross compilation, package dependencies
2838 The distinction between @code{native-inputs} and @code{inputs} is
2839 necessary when considering cross-compilation. When cross-compiling,
2840 dependencies listed in @code{inputs} are built for the @emph{target}
2841 architecture; conversely, dependencies listed in @code{native-inputs}
2842 are built for the architecture of the @emph{build} machine.
2844 @code{native-inputs} is typically used to list tools needed at
2845 build time, but not at run time, such as Autoconf, Automake, pkg-config,
2846 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2847 this area (@pxref{Invoking guix lint}).
2849 @anchor{package-propagated-inputs}
2850 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2851 specified packages will be automatically installed alongside the package
2852 they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2853 package}}, for information on how @command{guix package} deals with
2856 For example this is necessary when a C/C++ library needs headers of
2857 another library to compile, or when a pkg-config file refers to another
2858 one @i{via} its @code{Requires} field.
2860 Another example where @code{propagated-inputs} is useful is for languages
2861 that lack a facility to record the run-time search path akin to the
2862 @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, and
2863 more. To ensure that libraries written in those languages can find
2864 library code they depend on at run time, run-time dependencies must be
2865 listed in @code{propagated-inputs} rather than @code{inputs}.
2867 @item @code{self-native-input?} (default: @code{#f})
2868 This is a Boolean field telling whether the package should use itself as
2869 a native input when cross-compiling.
2871 @item @code{outputs} (default: @code{'("out")})
2872 The list of output names of the package. @xref{Packages with Multiple
2873 Outputs}, for typical uses of additional outputs.
2875 @item @code{native-search-paths} (default: @code{'()})
2876 @itemx @code{search-paths} (default: @code{'()})
2877 A list of @code{search-path-specification} objects describing
2878 search-path environment variables honored by the package.
2880 @item @code{replacement} (default: @code{#f})
2881 This must be either @code{#f} or a package object that will be used as a
2882 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2885 @item @code{synopsis}
2886 A one-line description of the package.
2888 @item @code{description}
2889 A more elaborate description of the package.
2891 @item @code{license}
2892 @cindex license, of packages
2893 The license of the package; a value from @code{(guix licenses)},
2894 or a list of such values.
2896 @item @code{home-page}
2897 The URL to the home-page of the package, as a string.
2899 @item @code{supported-systems} (default: @var{%supported-systems})
2900 The list of systems supported by the package, as strings of the form
2901 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2903 @item @code{maintainers} (default: @code{'()})
2904 The list of maintainers of the package, as @code{maintainer} objects.
2906 @item @code{location} (default: source location of the @code{package} form)
2907 The source location of the package. It is useful to override this when
2908 inheriting from another package, in which case this field is not
2909 automatically corrected.
2914 @node origin Reference
2915 @subsection @code{origin} Reference
2917 This section summarizes all the options available in @code{origin}
2918 declarations (@pxref{Defining Packages}).
2920 @deftp {Data Type} origin
2921 This is the data type representing a source code origin.
2925 An object containing the URI of the source. The object type depends on
2926 the @code{method} (see below). For example, when using the
2927 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2928 values are: a URL represented as a string, or a list thereof.
2931 A procedure that handles the URI.
2936 @item @var{url-fetch} from @code{(guix download)}
2937 download a file from the HTTP, HTTPS, or FTP URL specified in the
2941 @item @var{git-fetch} from @code{(guix git-download)}
2942 clone the Git version control repository, and check out the revision
2943 specified in the @code{uri} field as a @code{git-reference} object; a
2944 @code{git-reference} looks like this:
2948 (url "git://git.debian.org/git/pkg-shadow/shadow")
2949 (commit "v4.1.5.1"))
2954 A bytevector containing the SHA-256 hash of the source. Typically the
2955 @code{base32} form is used here to generate the bytevector from a
2958 You can obtain this information using @code{guix download}
2959 (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking
2962 @item @code{file-name} (default: @code{#f})
2963 The file name under which the source code should be saved. When this is
2964 @code{#f}, a sensible default value will be used in most cases. In case
2965 the source is fetched from a URL, the file name from the URL will be
2966 used. For version control checkouts, it is recommended to provide the
2967 file name explicitly because the default is not very descriptive.
2969 @item @code{patches} (default: @code{'()})
2970 A list of file names containing patches to be applied to the source.
2972 This list of patches must be unconditional. In particular, it cannot
2973 depend on the value of @code{%current-system} or
2974 @code{%current-target-system}.
2976 @item @code{snippet} (default: @code{#f})
2977 A G-expression (@pxref{G-Expressions}) or S-expression that will be run
2978 in the source directory. This is a convenient way to modify the source,
2979 sometimes more convenient than a patch.
2981 @item @code{patch-flags} (default: @code{'("-p1")})
2982 A list of command-line flags that should be passed to the @code{patch}
2985 @item @code{patch-inputs} (default: @code{#f})
2986 Input packages or derivations to the patching process. When this is
2987 @code{#f}, the usual set of inputs necessary for patching are provided,
2988 such as GNU@tie{}Patch.
2990 @item @code{modules} (default: @code{'()})
2991 A list of Guile modules that should be loaded during the patching
2992 process and while running the code in the @code{snippet} field.
2994 @item @code{patch-guile} (default: @code{#f})
2995 The Guile package that should be used in the patching process. When
2996 this is @code{#f}, a sensible default is used.
3002 @section Build Systems
3004 @cindex build system
3005 Each package definition specifies a @dfn{build system} and arguments for
3006 that build system (@pxref{Defining Packages}). This @code{build-system}
3007 field represents the build procedure of the package, as well as implicit
3008 dependencies of that build procedure.
3010 Build systems are @code{<build-system>} objects. The interface to
3011 create and manipulate them is provided by the @code{(guix build-system)}
3012 module, and actual build systems are exported by specific modules.
3014 @cindex bag (low-level package representation)
3015 Under the hood, build systems first compile package objects to
3016 @dfn{bags}. A @dfn{bag} is like a package, but with less
3017 ornamentation---in other words, a bag is a lower-level representation of
3018 a package, which includes all the inputs of that package, including some
3019 that were implicitly added by the build system. This intermediate
3020 representation is then compiled to a derivation (@pxref{Derivations}).
3022 Build systems accept an optional list of @dfn{arguments}. In package
3023 definitions, these are passed @i{via} the @code{arguments} field
3024 (@pxref{Defining Packages}). They are typically keyword arguments
3025 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
3026 Guile Reference Manual}). The value of these arguments is usually
3027 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
3028 by the daemon (@pxref{Derivations}).
3030 The main build system is @var{gnu-build-system}, which implements the
3031 standard build procedure for GNU and many other packages. It
3032 is provided by the @code{(guix build-system gnu)} module.
3034 @defvr {Scheme Variable} gnu-build-system
3035 @var{gnu-build-system} represents the GNU Build System, and variants
3036 thereof (@pxref{Configuration, configuration and makefile conventions,,
3037 standards, GNU Coding Standards}).
3039 @cindex build phases
3040 In a nutshell, packages using it are configured, built, and installed with
3041 the usual @code{./configure && make && make check && make install}
3042 command sequence. In practice, a few additional steps are often needed.
3043 All these steps are split up in separate @dfn{phases},
3044 notably@footnote{Please see the @code{(guix build gnu-build-system)}
3045 modules for more details about the build phases.}:
3049 Unpack the source tarball, and change the current directory to the
3050 extracted source tree. If the source is actually a directory, copy it
3051 to the build tree, and enter that directory.
3053 @item patch-source-shebangs
3054 Patch shebangs encountered in source files so they refer to the right
3055 store file names. For instance, this changes @code{#!/bin/sh} to
3056 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
3059 Run the @file{configure} script with a number of default options, such
3060 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
3061 by the @code{#:configure-flags} argument.
3064 Run @code{make} with the list of flags specified with
3065 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
3066 (the default), build with @code{make -j}.
3069 Run @code{make check}, or some other target specified with
3070 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
3071 @code{#:parallel-tests?} argument is true (the default), run @code{make
3075 Run @code{make install} with the flags listed in @code{#:make-flags}.
3077 @item patch-shebangs
3078 Patch shebangs on the installed executable files.
3081 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
3082 is false), copying them to the @code{debug} output when available
3083 (@pxref{Installing Debugging Files}).
3086 @vindex %standard-phases
3087 The build-side module @code{(guix build gnu-build-system)} defines
3088 @var{%standard-phases} as the default list of build phases.
3089 @var{%standard-phases} is a list of symbol/procedure pairs, where the
3090 procedure implements the actual phase.
3092 The list of phases used for a particular package can be changed with the
3093 @code{#:phases} parameter. For instance, passing:
3096 #:phases (modify-phases %standard-phases (delete 'configure))
3099 means that all the phases described above will be used, except the
3100 @code{configure} phase.
3102 In addition, this build system ensures that the ``standard'' environment
3103 for GNU packages is available. This includes tools such as GCC, libc,
3104 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
3105 build-system gnu)} module for a complete list). We call these the
3106 @dfn{implicit inputs} of a package, because package definitions do not
3107 have to mention them.
3110 Other @code{<build-system>} objects are defined to support other
3111 conventions and tools used by free software packages. They inherit most
3112 of @var{gnu-build-system}, and differ mainly in the set of inputs
3113 implicitly added to the build process, and in the list of phases
3114 executed. Some of these build systems are listed below.
3116 @defvr {Scheme Variable} ant-build-system
3117 This variable is exported by @code{(guix build-system ant)}. It
3118 implements the build procedure for Java packages that can be built with
3119 @url{http://ant.apache.org/, Ant build tool}.
3121 It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as
3122 provided by the @code{icedtea} package to the set of inputs. Different
3123 packages can be specified with the @code{#:ant} and @code{#:jdk}
3124 parameters, respectively.
3126 When the original package does not provide a suitable Ant build file,
3127 the parameter @code{#:jar-name} can be used to generate a minimal Ant
3128 build file @file{build.xml} with tasks to build the specified jar
3131 The parameter @code{#:build-target} can be used to specify the Ant task
3132 that should be run during the @code{build} phase. By default the
3133 ``jar'' task will be run.
3137 @defvr {Scheme Variable} asdf-build-system/source
3138 @defvrx {Scheme Variable} asdf-build-system/sbcl
3139 @defvrx {Scheme Variable} asdf-build-system/ecl
3141 These variables, exported by @code{(guix build-system asdf)}, implement
3142 build procedures for Common Lisp packages using
3143 @url{https://common-lisp.net/project/asdf/, ``ASDF''}. ASDF is a system
3144 definition facility for Common Lisp programs and libraries.
3146 The @code{asdf-build-system/source} system installs the packages in
3147 source form, and can be loaded using any common lisp implementation, via
3148 ASDF. The others, such as @code{asdf-build-system/sbcl}, install binary
3149 systems in the format which a particular implementation understands.
3150 These build systems can also be used to produce executable programs, or
3151 lisp images which contain a set of packages pre-loaded.
3153 The build system uses naming conventions. For binary packages, the
3154 package itself as well as its run-time dependencies should begin their
3155 name with the lisp implementation, such as @code{sbcl-} for
3156 @code{asdf-build-system/sbcl}. Beginning the input name with this
3157 prefix will allow the build system to encode its location into the
3158 resulting library, so that the input can be found at run-time.
3160 If dependencies are used only for tests, it is convenient to use a
3161 different prefix in order to avoid having a run-time dependency on such
3162 systems. For example,
3165 (define-public sbcl-bordeaux-threads
3168 (native-inputs `(("tests:cl-fiveam" ,sbcl-fiveam)))
3172 Additionally, the corresponding source package should be labeled using
3173 the same convention as python packages (see @ref{Python Modules}), using
3174 the @code{cl-} prefix.
3176 For binary packages, each system should be defined as a Guix package.
3177 If one package @code{origin} contains several systems, package variants
3178 can be created in order to build all the systems. Source packages,
3179 which use @code{asdf-build-system/source}, may contain several systems.
3181 In order to create executable programs and images, the build-side
3182 procedures @code{build-program} and @code{build-image} can be used.
3183 They should be called in a build phase after the @code{create-symlinks}
3184 phase, so that the system which was just built can be used within the
3185 resulting image. @code{build-program} requires a list of Common Lisp
3186 expressions to be passed as the @code{#:entry-program} argument.
3188 If the system is not defined within its own @code{.asd} file of the same
3189 name, then the @code{#:asd-file} parameter should be used to specify
3190 which file the system is defined in.
3194 @defvr {Scheme Variable} cargo-build-system
3195 @cindex Rust programming language
3196 @cindex Cargo (Rust build system)
3197 This variable is exported by @code{(guix build-system cargo)}. It
3198 supports builds of packages using Cargo, the build tool of the
3199 @uref{https://www.rust-lang.org, Rust programming language}.
3201 In its @code{configure} phase, this build system replaces dependencies
3202 specified in the @file{Carto.toml} file with inputs to the Guix package.
3203 The @code{install} phase installs the binaries, and it also installs the
3204 source code and @file{Cargo.toml} file.
3207 @defvr {Scheme Variable} cmake-build-system
3208 This variable is exported by @code{(guix build-system cmake)}. It
3209 implements the build procedure for packages using the
3210 @url{http://www.cmake.org, CMake build tool}.
3212 It automatically adds the @code{cmake} package to the set of inputs.
3213 Which package is used can be specified with the @code{#:cmake}
3216 The @code{#:configure-flags} parameter is taken as a list of flags
3217 passed to the @command{cmake} command. The @code{#:build-type}
3218 parameter specifies in abstract terms the flags passed to the compiler;
3219 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
3220 debugging information''), which roughly means that code is compiled with
3221 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
3224 @defvr {Scheme Variable} glib-or-gtk-build-system
3225 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
3226 is intended for use with packages making use of GLib or GTK+.
3228 This build system adds the following two phases to the ones defined by
3229 @var{gnu-build-system}:
3232 @item glib-or-gtk-wrap
3233 The phase @code{glib-or-gtk-wrap} ensures that programs in
3234 @file{bin/} are able to find GLib ``schemas'' and
3235 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
3236 modules}. This is achieved by wrapping the programs in launch scripts
3237 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
3238 environment variables.
3240 It is possible to exclude specific package outputs from that wrapping
3241 process by listing their names in the
3242 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
3243 when an output is known not to contain any GLib or GTK+ binaries, and
3244 where wrapping would gratuitously add a dependency of that output on
3247 @item glib-or-gtk-compile-schemas
3248 The phase @code{glib-or-gtk-compile-schemas} makes sure that all
3249 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
3250 GSettings schemas} of GLib are compiled. Compilation is performed by the
3251 @command{glib-compile-schemas} program. It is provided by the package
3252 @code{glib:bin} which is automatically imported by the build system.
3253 The @code{glib} package providing @command{glib-compile-schemas} can be
3254 specified with the @code{#:glib} parameter.
3257 Both phases are executed after the @code{install} phase.
3260 @defvr {Scheme Variable} python-build-system
3261 This variable is exported by @code{(guix build-system python)}. It
3262 implements the more or less standard build procedure used by Python
3263 packages, which consists in running @code{python setup.py build} and
3264 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
3266 For packages that install stand-alone Python programs under @code{bin/},
3267 it takes care of wrapping these programs so that their @code{PYTHONPATH}
3268 environment variable points to all the Python libraries they depend on.
3270 Which Python package is used to perform the build can be specified with
3271 the @code{#:python} parameter. This is a useful way to force a package
3272 to be built for a specific version of the Python interpreter, which
3273 might be necessary if the package is only compatible with a single
3274 interpreter version.
3276 By default guix calls @code{setup.py} under control of
3277 @code{setuptools}, much like @command{pip} does. Some packages are not
3278 compatible with setuptools (and pip), thus you can disable this by
3279 setting the @code{#:use-setuptools} parameter to @code{#f}.
3282 @defvr {Scheme Variable} perl-build-system
3283 This variable is exported by @code{(guix build-system perl)}. It
3284 implements the standard build procedure for Perl packages, which either
3285 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
3286 followed by @code{Build} and @code{Build install}; or in running
3287 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
3288 @code{make} and @code{make install}, depending on which of
3289 @code{Build.PL} or @code{Makefile.PL} is present in the package
3290 distribution. Preference is given to the former if both @code{Build.PL}
3291 and @code{Makefile.PL} exist in the package distribution. This
3292 preference can be reversed by specifying @code{#t} for the
3293 @code{#:make-maker?} parameter.
3295 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
3296 passes flags specified by the @code{#:make-maker-flags} or
3297 @code{#:module-build-flags} parameter, respectively.
3299 Which Perl package is used can be specified with @code{#:perl}.
3302 @defvr {Scheme Variable} r-build-system
3303 This variable is exported by @code{(guix build-system r)}. It
3304 implements the build procedure used by @uref{http://r-project.org, R}
3305 packages, which essentially is little more than running @code{R CMD
3306 INSTALL --library=/gnu/store/@dots{}} in an environment where
3307 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
3308 are run after installation using the R function
3309 @code{tools::testInstalledPackage}.
3312 @defvr {Scheme Variable} ruby-build-system
3313 This variable is exported by @code{(guix build-system ruby)}. It
3314 implements the RubyGems build procedure used by Ruby packages, which
3315 involves running @code{gem build} followed by @code{gem install}.
3317 The @code{source} field of a package that uses this build system
3318 typically references a gem archive, since this is the format that Ruby
3319 developers use when releasing their software. The build system unpacks
3320 the gem archive, potentially patches the source, runs the test suite,
3321 repackages the gem, and installs it. Additionally, directories and
3322 tarballs may be referenced to allow building unreleased gems from Git or
3323 a traditional source release tarball.
3325 Which Ruby package is used can be specified with the @code{#:ruby}
3326 parameter. A list of additional flags to be passed to the @command{gem}
3327 command can be specified with the @code{#:gem-flags} parameter.
3330 @defvr {Scheme Variable} waf-build-system
3331 This variable is exported by @code{(guix build-system waf)}. It
3332 implements a build procedure around the @code{waf} script. The common
3333 phases---@code{configure}, @code{build}, and @code{install}---are
3334 implemented by passing their names as arguments to the @code{waf}
3337 The @code{waf} script is executed by the Python interpreter. Which
3338 Python package is used to run the script can be specified with the
3339 @code{#:python} parameter.
3342 @defvr {Scheme Variable} haskell-build-system
3343 This variable is exported by @code{(guix build-system haskell)}. It
3344 implements the Cabal build procedure used by Haskell packages, which
3345 involves running @code{runhaskell Setup.hs configure
3346 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
3347 Instead of installing the package by running @code{runhaskell Setup.hs
3348 install}, to avoid trying to register libraries in the read-only
3349 compiler store directory, the build system uses @code{runhaskell
3350 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
3351 addition, the build system generates the package documentation by
3352 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
3353 is passed. Optional Haddock parameters can be passed with the help of
3354 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
3355 not found, the build system looks for @code{Setup.lhs} instead.
3357 Which Haskell compiler is used can be specified with the @code{#:haskell}
3358 parameter which defaults to @code{ghc}.
3361 @defvr {Scheme Variable} emacs-build-system
3362 This variable is exported by @code{(guix build-system emacs)}. It
3363 implements an installation procedure similar to the packaging system
3364 of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
3366 It first creates the @code{@var{package}-autoloads.el} file, then it
3367 byte compiles all Emacs Lisp files. Differently from the Emacs
3368 packaging system, the Info documentation files are moved to the standard
3369 documentation directory and the @file{dir} file is deleted. Each
3370 package is installed in its own directory under
3371 @file{share/emacs/site-lisp/guix.d}.
3374 Lastly, for packages that do not need anything as sophisticated, a
3375 ``trivial'' build system is provided. It is trivial in the sense that
3376 it provides basically no support: it does not pull any implicit inputs,
3377 and does not have a notion of build phases.
3379 @defvr {Scheme Variable} trivial-build-system
3380 This variable is exported by @code{(guix build-system trivial)}.
3382 This build system requires a @code{#:builder} argument. This argument
3383 must be a Scheme expression that builds the package output(s)---as
3384 with @code{build-expression->derivation} (@pxref{Derivations,
3385 @code{build-expression->derivation}}).
3395 Conceptually, the @dfn{store} is the place where derivations that have
3396 been built successfully are stored---by default, @file{/gnu/store}.
3397 Sub-directories in the store are referred to as @dfn{store items} or
3398 sometimes @dfn{store paths}. The store has an associated database that
3399 contains information such as the store paths referred to by each store
3400 path, and the list of @emph{valid} store items---results of successful
3401 builds. This database resides in @file{@var{localstatedir}/guix/db},
3402 where @var{localstatedir} is the state directory specified @i{via}
3403 @option{--localstatedir} at configure time, usually @file{/var}.
3405 The store is @emph{always} accessed by the daemon on behalf of its clients
3406 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
3407 connect to the daemon over a Unix-domain socket, send requests to it,
3408 and read the result---these are remote procedure calls, or RPCs.
3411 Users must @emph{never} modify files under @file{/gnu/store} directly.
3412 This would lead to inconsistencies and break the immutability
3413 assumptions of Guix's functional model (@pxref{Introduction}).
3415 @xref{Invoking guix gc, @command{guix gc --verify}}, for information on
3416 how to check the integrity of the store and attempt recovery from
3417 accidental modifications.
3420 The @code{(guix store)} module provides procedures to connect to the
3421 daemon, and to perform RPCs. These are described below.
3423 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
3424 Connect to the daemon over the Unix-domain socket at @var{file}. When
3425 @var{reserve-space?} is true, instruct it to reserve a little bit of
3426 extra space on the file system so that the garbage collector can still
3427 operate should the disk become full. Return a server object.
3429 @var{file} defaults to @var{%default-socket-path}, which is the normal
3430 location given the options that were passed to @command{configure}.
3433 @deffn {Scheme Procedure} close-connection @var{server}
3434 Close the connection to @var{server}.
3437 @defvr {Scheme Variable} current-build-output-port
3438 This variable is bound to a SRFI-39 parameter, which refers to the port
3439 where build and error logs sent by the daemon should be written.
3442 Procedures that make RPCs all take a server object as their first
3445 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
3446 @cindex invalid store items
3447 Return @code{#t} when @var{path} designates a valid store item and
3448 @code{#f} otherwise (an invalid item may exist on disk but still be
3449 invalid, for instance because it is the result of an aborted or failed
3452 A @code{&nix-protocol-error} condition is raised if @var{path} is not
3453 prefixed by the store directory (@file{/gnu/store}).
3456 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
3457 Add @var{text} under file @var{name} in the store, and return its store
3458 path. @var{references} is the list of store paths referred to by the
3459 resulting store path.
3462 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
3463 Build @var{derivations} (a list of @code{<derivation>} objects or
3464 derivation paths), and return when the worker is done building them.
3465 Return @code{#t} on success.
3468 Note that the @code{(guix monads)} module provides a monad as well as
3469 monadic versions of the above procedures, with the goal of making it
3470 more convenient to work with code that accesses the store (@pxref{The
3474 @i{This section is currently incomplete.}
3477 @section Derivations
3480 Low-level build actions and the environment in which they are performed
3481 are represented by @dfn{derivations}. A derivation contains the
3482 following pieces of information:
3486 The outputs of the derivation---derivations produce at least one file or
3487 directory in the store, but may produce more.
3490 The inputs of the derivations, which may be other derivations or plain
3491 files in the store (patches, build scripts, etc.)
3494 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
3497 The file name of a build script in the store, along with the arguments
3501 A list of environment variables to be defined.
3505 @cindex derivation path
3506 Derivations allow clients of the daemon to communicate build actions to
3507 the store. They exist in two forms: as an in-memory representation,
3508 both on the client- and daemon-side, and as files in the store whose
3509 name end in @code{.drv}---these files are referred to as @dfn{derivation
3510 paths}. Derivations paths can be passed to the @code{build-derivations}
3511 procedure to perform the build actions they prescribe (@pxref{The
3514 The @code{(guix derivations)} module provides a representation of
3515 derivations as Scheme objects, along with procedures to create and
3516 otherwise manipulate derivations. The lowest-level primitive to create
3517 a derivation is the @code{derivation} procedure:
3519 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
3520 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3521 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
3522 [#:system (%current-system)] [#:references-graphs #f] @
3523 [#:allowed-references #f] [#:disallowed-references #f] @
3524 [#:leaked-env-vars #f] [#:local-build? #f] @
3525 [#:substitutable? #t]
3526 Build a derivation with the given arguments, and return the resulting
3527 @code{<derivation>} object.
3529 When @var{hash} and @var{hash-algo} are given, a
3530 @dfn{fixed-output derivation} is created---i.e., one whose result is
3531 known in advance, such as a file download. If, in addition,
3532 @var{recursive?} is true, then that fixed output may be an executable
3533 file or a directory and @var{hash} must be the hash of an archive
3534 containing this output.
3536 When @var{references-graphs} is true, it must be a list of file
3537 name/store path pairs. In that case, the reference graph of each store
3538 path is exported in the build environment in the corresponding file, in
3539 a simple text format.
3541 When @var{allowed-references} is true, it must be a list of store items
3542 or outputs that the derivation's output may refer to. Likewise,
3543 @var{disallowed-references}, if true, must be a list of things the
3544 outputs may @emph{not} refer to.
3546 When @var{leaked-env-vars} is true, it must be a list of strings
3547 denoting environment variables that are allowed to ``leak'' from the
3548 daemon's environment to the build environment. This is only applicable
3549 to fixed-output derivations---i.e., when @var{hash} is true. The main
3550 use is to allow variables such as @code{http_proxy} to be passed to
3551 derivations that download files.
3553 When @var{local-build?} is true, declare that the derivation is not a
3554 good candidate for offloading and should rather be built locally
3555 (@pxref{Daemon Offload Setup}). This is the case for small derivations
3556 where the costs of data transfers would outweigh the benefits.
3558 When @var{substitutable?} is false, declare that substitutes of the
3559 derivation's output should not be used (@pxref{Substitutes}). This is
3560 useful, for instance, when building packages that capture details of the
3561 host CPU instruction set.
3565 Here's an example with a shell script as its builder, assuming
3566 @var{store} is an open connection to the daemon, and @var{bash} points
3567 to a Bash executable in the store:
3570 (use-modules (guix utils)
3574 (let ((builder ; add the Bash script to the store
3575 (add-text-to-store store "my-builder.sh"
3576 "echo hello world > $out\n" '())))
3577 (derivation store "foo"
3578 bash `("-e" ,builder)
3579 #:inputs `((,bash) (,builder))
3580 #:env-vars '(("HOME" . "/homeless"))))
3581 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3584 As can be guessed, this primitive is cumbersome to use directly. A
3585 better approach is to write build scripts in Scheme, of course! The
3586 best course of action for that is to write the build code as a
3587 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3588 information, @pxref{G-Expressions}.
3590 Once upon a time, @code{gexp->derivation} did not exist and constructing
3591 derivations with build code written in Scheme was achieved with
3592 @code{build-expression->derivation}, documented below. This procedure
3593 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3595 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3596 @var{name} @var{exp} @
3597 [#:system (%current-system)] [#:inputs '()] @
3598 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3599 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3600 [#:references-graphs #f] [#:allowed-references #f] @
3601 [#:disallowed-references #f] @
3602 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3603 Return a derivation that executes Scheme expression @var{exp} as a
3604 builder for derivation @var{name}. @var{inputs} must be a list of
3605 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3606 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3607 modules from the current search path to be copied in the store,
3608 compiled, and made available in the load path during the execution of
3609 @var{exp}---e.g., @code{((guix build utils) (guix build
3610 gnu-build-system))}.
3612 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3613 to a list of output/path pairs, and where @code{%build-inputs} is bound
3614 to a list of string/output-path pairs made from @var{inputs}.
3615 Optionally, @var{env-vars} is a list of string pairs specifying the name
3616 and value of environment variables visible to the builder. The builder
3617 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3618 @var{exp} returns @code{#f}, the build is considered to have failed.
3620 @var{exp} is built using @var{guile-for-build} (a derivation). When
3621 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3622 @code{%guile-for-build} fluid is used instead.
3624 See the @code{derivation} procedure for the meaning of
3625 @var{references-graphs}, @var{allowed-references},
3626 @var{disallowed-references}, @var{local-build?}, and
3627 @var{substitutable?}.
3631 Here's an example of a single-output derivation that creates a directory
3632 containing one file:
3635 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3636 (mkdir out) ; create /gnu/store/@dots{}-goo
3637 (call-with-output-file (string-append out "/test")
3639 (display '(hello guix) p))))))
3640 (build-expression->derivation store "goo" builder))
3642 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3646 @node The Store Monad
3647 @section The Store Monad
3651 The procedures that operate on the store described in the previous
3652 sections all take an open connection to the build daemon as their first
3653 argument. Although the underlying model is functional, they either have
3654 side effects or depend on the current state of the store.
3656 The former is inconvenient: the connection to the build daemon has to be
3657 carried around in all those functions, making it impossible to compose
3658 functions that do not take that parameter with functions that do. The
3659 latter can be problematic: since store operations have side effects
3660 and/or depend on external state, they have to be properly sequenced.
3662 @cindex monadic values
3663 @cindex monadic functions
3664 This is where the @code{(guix monads)} module comes in. This module
3665 provides a framework for working with @dfn{monads}, and a particularly
3666 useful monad for our uses, the @dfn{store monad}. Monads are a
3667 construct that allows two things: associating ``context'' with values
3668 (in our case, the context is the store), and building sequences of
3669 computations (here computations include accesses to the store). Values
3670 in a monad---values that carry this additional context---are called
3671 @dfn{monadic values}; procedures that return such values are called
3672 @dfn{monadic procedures}.
3674 Consider this ``normal'' procedure:
3677 (define (sh-symlink store)
3678 ;; Return a derivation that symlinks the 'bash' executable.
3679 (let* ((drv (package-derivation store bash))
3680 (out (derivation->output-path drv))
3681 (sh (string-append out "/bin/bash")))
3682 (build-expression->derivation store "sh"
3683 `(symlink ,sh %output))))
3686 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3687 as a monadic function:
3690 (define (sh-symlink)
3691 ;; Same, but return a monadic value.
3692 (mlet %store-monad ((drv (package->derivation bash)))
3693 (gexp->derivation "sh"
3694 #~(symlink (string-append #$drv "/bin/bash")
3698 There are several things to note in the second version: the @code{store}
3699 parameter is now implicit and is ``threaded'' in the calls to the
3700 @code{package->derivation} and @code{gexp->derivation} monadic
3701 procedures, and the monadic value returned by @code{package->derivation}
3702 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3704 As it turns out, the call to @code{package->derivation} can even be
3705 omitted since it will take place implicitly, as we will see later
3706 (@pxref{G-Expressions}):
3709 (define (sh-symlink)
3710 (gexp->derivation "sh"
3711 #~(symlink (string-append #$bash "/bin/bash")
3716 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3717 @c for the funny quote.
3718 Calling the monadic @code{sh-symlink} has no effect. As someone once
3719 said, ``you exit a monad like you exit a building on fire: by running''.
3720 So, to exit the monad and get the desired effect, one must use
3721 @code{run-with-store}:
3724 (run-with-store (open-connection) (sh-symlink))
3725 @result{} /gnu/store/...-sh-symlink
3728 Note that the @code{(guix monad-repl)} module extends the Guile REPL with
3729 new ``meta-commands'' to make it easier to deal with monadic procedures:
3730 @code{run-in-store}, and @code{enter-store-monad}. The former is used
3731 to ``run'' a single monadic value through the store:
3734 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3735 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3738 The latter enters a recursive REPL, where all the return values are
3739 automatically run through the store:
3742 scheme@@(guile-user)> ,enter-store-monad
3743 store-monad@@(guile-user) [1]> (package->derivation hello)
3744 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3745 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3746 $3 = "/gnu/store/@dots{}-foo"
3747 store-monad@@(guile-user) [1]> ,q
3748 scheme@@(guile-user)>
3752 Note that non-monadic values cannot be returned in the
3753 @code{store-monad} REPL.
3755 The main syntactic forms to deal with monads in general are provided by
3756 the @code{(guix monads)} module and are described below.
3758 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3759 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3763 @deffn {Scheme Syntax} return @var{val}
3764 Return a monadic value that encapsulates @var{val}.
3767 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3768 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3769 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3770 referred to as ``bind'', but that name denotes an unrelated procedure in
3771 Guile. Thus we use this somewhat cryptic symbol inherited from the
3772 Haskell language.}. There can be one @var{mproc} or several of them, as
3777 (with-monad %state-monad
3779 (lambda (x) (return (+ 1 x)))
3780 (lambda (x) (return (* 2 x)))))
3784 @result{} some-state
3788 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3790 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3792 Bind the variables @var{var} to the monadic values @var{mval} in
3793 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3794 ``normal'' value @var{val}, as per @code{let}.
3796 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3797 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3800 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3801 Bind @var{mexp} and the following monadic expressions in sequence,
3802 returning the result of the last expression.
3804 This is akin to @code{mlet}, except that the return values of the
3805 monadic expressions are ignored. In that sense, it is analogous to
3806 @code{begin}, but applied to monadic expressions.
3810 The @code{(guix monads)} module provides the @dfn{state monad}, which
3811 allows an additional value---the state---to be @emph{threaded} through
3812 monadic procedure calls.
3814 @defvr {Scheme Variable} %state-monad
3815 The state monad. Procedures in the state monad can access and change
3816 the state that is threaded.
3818 Consider the example below. The @code{square} procedure returns a value
3819 in the state monad. It returns the square of its argument, but also
3820 increments the current state value:
3824 (mlet %state-monad ((count (current-state)))
3825 (mbegin %state-monad
3826 (set-current-state (+ 1 count))
3829 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3834 When ``run'' through @var{%state-monad}, we obtain that additional state
3835 value, which is the number of @code{square} calls.
3838 @deffn {Monadic Procedure} current-state
3839 Return the current state as a monadic value.
3842 @deffn {Monadic Procedure} set-current-state @var{value}
3843 Set the current state to @var{value} and return the previous state as a
3847 @deffn {Monadic Procedure} state-push @var{value}
3848 Push @var{value} to the current state, which is assumed to be a list,
3849 and return the previous state as a monadic value.
3852 @deffn {Monadic Procedure} state-pop
3853 Pop a value from the current state and return it as a monadic value.
3854 The state is assumed to be a list.
3857 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3858 Run monadic value @var{mval} starting with @var{state} as the initial
3859 state. Return two values: the resulting value, and the resulting state.
3862 The main interface to the store monad, provided by the @code{(guix
3863 store)} module, is as follows.
3865 @defvr {Scheme Variable} %store-monad
3866 The store monad---an alias for @var{%state-monad}.
3868 Values in the store monad encapsulate accesses to the store. When its
3869 effect is needed, a value of the store monad must be ``evaluated'' by
3870 passing it to the @code{run-with-store} procedure (see below.)
3873 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3874 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3875 open store connection.
3878 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3879 Return as a monadic value the absolute file name in the store of the file
3880 containing @var{text}, a string. @var{references} is a list of store items that the
3881 resulting text file refers to; it defaults to the empty list.
3884 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3885 [#:recursive? #t] [#:select? (const #t)]
3886 Return the name of @var{file} once interned in the store. Use
3887 @var{name} as its store name, or the basename of @var{file} if
3888 @var{name} is omitted.
3890 When @var{recursive?} is true, the contents of @var{file} are added
3891 recursively; if @var{file} designates a flat file and @var{recursive?}
3892 is true, its contents are added, and its permission bits are kept.
3894 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3895 @var{stat})} for each directory entry, where @var{file} is the entry's
3896 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3897 entries for which @var{select?} does not return true.
3899 The example below adds a file to the store, under two different names:
3902 (run-with-store (open-connection)
3903 (mlet %store-monad ((a (interned-file "README"))
3904 (b (interned-file "README" "LEGU-MIN")))
3905 (return (list a b))))
3907 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3912 The @code{(guix packages)} module exports the following package-related
3915 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3916 [#:system (%current-system)] [#:target #f] @
3919 value in the absolute file name of @var{file} within the @var{output}
3920 directory of @var{package}. When @var{file} is omitted, return the name
3921 of the @var{output} directory of @var{package}. When @var{target} is
3922 true, use it as a cross-compilation target triplet.
3925 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3926 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3927 @var{target} [@var{system}]
3928 Monadic version of @code{package-derivation} and
3929 @code{package-cross-derivation} (@pxref{Defining Packages}).
3934 @section G-Expressions
3936 @cindex G-expression
3937 @cindex build code quoting
3938 So we have ``derivations'', which represent a sequence of build actions
3939 to be performed to produce an item in the store (@pxref{Derivations}).
3940 These build actions are performed when asking the daemon to actually
3941 build the derivations; they are run by the daemon in a container
3942 (@pxref{Invoking guix-daemon}).
3944 @cindex strata of code
3945 It should come as no surprise that we like to write these build actions
3946 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3947 code@footnote{The term @dfn{stratum} in this context was coined by
3948 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3949 Kiselyov, who has written insightful
3950 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3951 on this topic}, refers to this kind of code generation as
3952 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3953 to the daemon, etc.---and the ``build code''---code that actually
3954 performs build actions, such as making directories, invoking
3955 @command{make}, etc.
3957 To describe a derivation and its build actions, one typically needs to
3958 embed build code inside host code. It boils down to manipulating build
3959 code as data, and the homoiconicity of Scheme---code has a direct
3960 representation as data---comes in handy for that. But we need more than
3961 the normal @code{quasiquote} mechanism in Scheme to construct build
3964 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3965 S-expressions adapted to build expressions. G-expressions, or
3966 @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
3967 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3968 @code{#$}, and @code{#$@@}), which are comparable to
3969 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
3970 respectively (@pxref{Expression Syntax, @code{quasiquote},, guile,
3971 GNU Guile Reference Manual}). However, there are major differences:
3975 Gexps are meant to be written to a file and run or manipulated by other
3979 When a high-level object such as a package or derivation is unquoted
3980 inside a gexp, the result is as if its output file name had been
3984 Gexps carry information about the packages or derivations they refer to,
3985 and these dependencies are automatically added as inputs to the build
3986 processes that use them.
3989 @cindex lowering, of high-level objects in gexps
3990 This mechanism is not limited to package and derivation
3991 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3992 derivations or files in the store can be defined,
3993 such that these objects can also be inserted
3994 into gexps. For example, a useful type of high-level objects that can be
3995 inserted in a gexp is ``file-like objects'', which make it easy to
3996 add files to the store and to refer to them in
3997 derivations and such (see @code{local-file} and @code{plain-file}
4000 To illustrate the idea, here is an example of a gexp:
4007 (symlink (string-append #$coreutils "/bin/ls")
4011 This gexp can be passed to @code{gexp->derivation}; we obtain a
4012 derivation that builds a directory containing exactly one symlink to
4013 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
4016 (gexp->derivation "the-thing" build-exp)
4019 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
4020 substituted to the reference to the @var{coreutils} package in the
4021 actual build code, and @var{coreutils} is automatically made an input to
4022 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
4023 output)}) is replaced by a string containing the directory name of the
4024 output of the derivation.
4026 @cindex cross compilation
4027 In a cross-compilation context, it is useful to distinguish between
4028 references to the @emph{native} build of a package---that can run on the
4029 host---versus references to cross builds of a package. To that end, the
4030 @code{#+} plays the same role as @code{#$}, but is a reference to a
4031 native package build:
4034 (gexp->derivation "vi"
4037 (system* (string-append #+coreutils "/bin/ln")
4039 (string-append #$emacs "/bin/emacs")
4040 (string-append #$output "/bin/vi")))
4041 #:target "mips64el-linux-gnu")
4045 In the example above, the native build of @var{coreutils} is used, so
4046 that @command{ln} can actually run on the host; but then the
4047 cross-compiled build of @var{emacs} is referenced.
4049 @cindex imported modules, for gexps
4050 @findex with-imported-modules
4051 Another gexp feature is @dfn{imported modules}: sometimes you want to be
4052 able to use certain Guile modules from the ``host environment'' in the
4053 gexp, so those modules should be imported in the ``build environment''.
4054 The @code{with-imported-modules} form allows you to express that:
4057 (let ((build (with-imported-modules '((guix build utils))
4059 (use-modules (guix build utils))
4060 (mkdir-p (string-append #$output "/bin"))))))
4061 (gexp->derivation "empty-dir"
4064 (display "success!\n")
4069 In this example, the @code{(guix build utils)} module is automatically
4070 pulled into the isolated build environment of our gexp, such that
4071 @code{(use-modules (guix build utils))} works as expected.
4073 @cindex module closure
4074 @findex source-module-closure
4075 Usually you want the @emph{closure} of the module to be imported---i.e.,
4076 the module itself and all the modules it depends on---rather than just
4077 the module; failing to do that, attempts to use the module will fail
4078 because of missing dependent modules. The @code{source-module-closure}
4079 procedure computes the closure of a module by looking at its source file
4080 headers, which comes in handy in this case:
4083 (use-modules (guix modules)) ;for 'source-module-closure'
4085 (with-imported-modules (source-module-closure
4086 '((guix build utils)
4088 (gexp->derivation "something-with-vms"
4090 (use-modules (guix build utils)
4095 The syntactic form to construct gexps is summarized below.
4097 @deffn {Scheme Syntax} #~@var{exp}
4098 @deffnx {Scheme Syntax} (gexp @var{exp})
4099 Return a G-expression containing @var{exp}. @var{exp} may contain one
4100 or more of the following forms:
4104 @itemx (ungexp @var{obj})
4105 Introduce a reference to @var{obj}. @var{obj} may have one of the
4106 supported types, for example a package or a
4107 derivation, in which case the @code{ungexp} form is replaced by its
4108 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
4110 If @var{obj} is a list, it is traversed and references to supported
4111 objects are substituted similarly.
4113 If @var{obj} is another gexp, its contents are inserted and its
4114 dependencies are added to those of the containing gexp.
4116 If @var{obj} is another kind of object, it is inserted as is.
4118 @item #$@var{obj}:@var{output}
4119 @itemx (ungexp @var{obj} @var{output})
4120 This is like the form above, but referring explicitly to the
4121 @var{output} of @var{obj}---this is useful when @var{obj} produces
4122 multiple outputs (@pxref{Packages with Multiple Outputs}).
4125 @itemx #+@var{obj}:output
4126 @itemx (ungexp-native @var{obj})
4127 @itemx (ungexp-native @var{obj} @var{output})
4128 Same as @code{ungexp}, but produces a reference to the @emph{native}
4129 build of @var{obj} when used in a cross compilation context.
4131 @item #$output[:@var{output}]
4132 @itemx (ungexp output [@var{output}])
4133 Insert a reference to derivation output @var{output}, or to the main
4134 output when @var{output} is omitted.
4136 This only makes sense for gexps passed to @code{gexp->derivation}.
4139 @itemx (ungexp-splicing @var{lst})
4140 Like the above, but splices the contents of @var{lst} inside the
4144 @itemx (ungexp-native-splicing @var{lst})
4145 Like the above, but refers to native builds of the objects listed in
4150 G-expressions created by @code{gexp} or @code{#~} are run-time objects
4151 of the @code{gexp?} type (see below.)
4154 @deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{}
4155 Mark the gexps defined in @var{body}@dots{} as requiring @var{modules}
4156 in their execution environment. @var{modules} must be a list of Guile
4157 module names, such as @code{'((guix build utils) (guix build gremlin))}.
4159 This form has @emph{lexical} scope: it has an effect on the gexps
4160 directly defined in @var{body}@dots{}, but not on those defined, say, in
4161 procedures called from @var{body}@dots{}.
4164 @deffn {Scheme Procedure} gexp? @var{obj}
4165 Return @code{#t} if @var{obj} is a G-expression.
4168 G-expressions are meant to be written to disk, either as code building
4169 some derivation, or as plain files in the store. The monadic procedures
4170 below allow you to do that (@pxref{The Store Monad}, for more
4171 information about monads.)
4173 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
4174 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
4175 [#:hash #f] [#:hash-algo #f] @
4176 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
4177 [#:module-path @var{%load-path}] @
4178 [#:references-graphs #f] [#:allowed-references #f] @
4179 [#:disallowed-references #f] @
4180 [#:leaked-env-vars #f] @
4181 [#:script-name (string-append @var{name} "-builder")] @
4182 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
4183 Return a derivation @var{name} that runs @var{exp} (a gexp) with
4184 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
4185 stored in a file called @var{script-name}. When @var{target} is true,
4186 it is used as the cross-compilation target triplet for packages referred
4189 @var{modules} is deprecated in favor of @code{with-imported-modules}.
4191 make @var{modules} available in the evaluation context of @var{exp};
4192 @var{modules} is a list of names of Guile modules searched in
4193 @var{module-path} to be copied in the store, compiled, and made available in
4194 the load path during the execution of @var{exp}---e.g., @code{((guix
4195 build utils) (guix build gnu-build-system))}.
4197 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
4200 When @var{references-graphs} is true, it must be a list of tuples of one of the
4204 (@var{file-name} @var{package})
4205 (@var{file-name} @var{package} @var{output})
4206 (@var{file-name} @var{derivation})
4207 (@var{file-name} @var{derivation} @var{output})
4208 (@var{file-name} @var{store-item})
4211 The right-hand-side of each element of @var{references-graphs} is automatically made
4212 an input of the build process of @var{exp}. In the build environment, each
4213 @var{file-name} contains the reference graph of the corresponding item, in a simple
4216 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
4217 In the latter case, the list denotes store items that the result is allowed to
4218 refer to. Any reference to another store item will lead to a build error.
4219 Similarly for @var{disallowed-references}, which can list items that must not be
4220 referenced by the outputs.
4222 The other arguments are as for @code{derivation} (@pxref{Derivations}).
4225 @cindex file-like objects
4226 The @code{local-file}, @code{plain-file}, @code{computed-file},
4227 @code{program-file}, and @code{scheme-file} procedures below return
4228 @dfn{file-like objects}. That is, when unquoted in a G-expression,
4229 these objects lead to a file in the store. Consider this G-expression:
4232 #~(system* #$(file-append glibc "/sbin/nscd") "-f"
4233 #$(local-file "/tmp/my-nscd.conf"))
4236 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
4237 to the store. Once expanded, for instance @i{via}
4238 @code{gexp->derivation}, the G-expression refers to that copy under
4239 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
4240 does not have any effect on what the G-expression does.
4241 @code{plain-file} can be used similarly; it differs in that the file
4242 content is directly passed as a string.
4244 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
4245 [#:recursive? #f] [#:select? (const #t)]
4246 Return an object representing local file @var{file} to add to the store; this
4247 object can be used in a gexp. If @var{file} is a relative file name, it is looked
4248 up relative to the source file where this form appears. @var{file} will be added to
4249 the store under @var{name}--by default the base name of @var{file}.
4251 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
4252 designates a flat file and @var{recursive?} is true, its contents are added, and its
4253 permission bits are kept.
4255 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
4256 @var{stat})} for each directory entry, where @var{file} is the entry's
4257 absolute file name and @var{stat} is the result of @code{lstat}; exclude
4258 entries for which @var{select?} does not return true.
4260 This is the declarative counterpart of the @code{interned-file} monadic
4261 procedure (@pxref{The Store Monad, @code{interned-file}}).
4264 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
4265 Return an object representing a text file called @var{name} with the given
4266 @var{content} (a string) to be added to the store.
4268 This is the declarative counterpart of @code{text-file}.
4271 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
4272 [#:options '(#:local-build? #t)]
4273 Return an object representing the store item @var{name}, a file or
4274 directory computed by @var{gexp}. @var{options}
4275 is a list of additional arguments to pass to @code{gexp->derivation}.
4277 This is the declarative counterpart of @code{gexp->derivation}.
4280 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
4281 Return an executable script @var{name} that runs @var{exp} using
4282 @var{guile}, with @var{exp}'s imported modules in its search path.
4284 The example below builds a script that simply invokes the @command{ls}
4288 (use-modules (guix gexp) (gnu packages base))
4290 (gexp->script "list-files"
4291 #~(execl #$(file-append coreutils "/bin/ls")
4295 When ``running'' it through the store (@pxref{The Store Monad,
4296 @code{run-with-store}}), we obtain a derivation that produces an
4297 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
4300 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
4302 (execl "/gnu/store/@dots{}-coreutils-8.22"/bin/ls" "ls")
4306 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
4308 Return an object representing the executable store item @var{name} that
4309 runs @var{gexp}. @var{guile} is the Guile package used to execute that
4312 This is the declarative counterpart of @code{gexp->script}.
4315 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @
4316 [#:set-load-path? #t]
4317 Return a derivation that builds a file @var{name} containing @var{exp}.
4318 When @var{set-load-path?} is true, emit code in the resulting file to
4319 set @code{%load-path} and @code{%load-compiled-path} to honor
4320 @var{exp}'s imported modules.
4322 The resulting file holds references to all the dependencies of @var{exp}
4323 or a subset thereof.
4326 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
4327 Return an object representing the Scheme file @var{name} that contains
4330 This is the declarative counterpart of @code{gexp->file}.
4333 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
4334 Return as a monadic value a derivation that builds a text file
4335 containing all of @var{text}. @var{text} may list, in addition to
4336 strings, objects of any type that can be used in a gexp: packages,
4337 derivations, local file objects, etc. The resulting store file holds
4338 references to all these.
4340 This variant should be preferred over @code{text-file} anytime the file
4341 to create will reference items from the store. This is typically the
4342 case when building a configuration file that embeds store file names,
4346 (define (profile.sh)
4347 ;; Return the name of a shell script in the store that
4348 ;; initializes the 'PATH' environment variable.
4349 (text-file* "profile.sh"
4350 "export PATH=" coreutils "/bin:"
4351 grep "/bin:" sed "/bin\n"))
4354 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
4355 will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby
4356 preventing them from being garbage-collected during its lifetime.
4359 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
4360 Return an object representing store file @var{name} containing
4361 @var{text}. @var{text} is a sequence of strings and file-like objects,
4365 (mixed-text-file "profile"
4366 "export PATH=" coreutils "/bin:" grep "/bin")
4369 This is the declarative counterpart of @code{text-file*}.
4372 @deffn {Scheme Procedure} file-append @var{obj} @var{suffix} @dots{}
4373 Return a file-like object that expands to the concatenation of @var{obj}
4374 and @var{suffix}, where @var{obj} is a lowerable object and each
4375 @var{suffix} is a string.
4377 As an example, consider this gexp:
4380 (gexp->script "run-uname"
4381 #~(system* #$(file-append coreutils
4385 The same effect could be achieved with:
4388 (gexp->script "run-uname"
4389 #~(system* (string-append #$coreutils
4393 There is one difference though: in the @code{file-append} case, the
4394 resulting script contains the absolute file name as a string, whereas in
4395 the second case, the resulting script contains a @code{(string-append
4396 @dots{})} expression to construct the file name @emph{at run time}.
4400 Of course, in addition to gexps embedded in ``host'' code, there are
4401 also modules containing build tools. To make it clear that they are
4402 meant to be used in the build stratum, these modules are kept in the
4403 @code{(guix build @dots{})} name space.
4405 @cindex lowering, of high-level objects in gexps
4406 Internally, high-level objects are @dfn{lowered}, using their compiler,
4407 to either derivations or store items. For instance, lowering a package
4408 yields a derivation, and lowering a @code{plain-file} yields a store
4409 item. This is achieved using the @code{lower-object} monadic procedure.
4411 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
4413 Return as a value in @var{%store-monad} the derivation or store item
4414 corresponding to @var{obj} for @var{system}, cross-compiling for
4415 @var{target} if @var{target} is true. @var{obj} must be an object that
4416 has an associated gexp compiler, such as a @code{<package>}.
4420 @c *********************************************************************
4424 This section describes Guix command-line utilities. Some of them are
4425 primarily targeted at developers and users who write new package
4426 definitions, while others are more generally useful. They complement
4427 the Scheme programming interface of Guix in a convenient way.
4430 * Invoking guix build:: Building packages from the command line.
4431 * Invoking guix edit:: Editing package definitions.
4432 * Invoking guix download:: Downloading a file and printing its hash.
4433 * Invoking guix hash:: Computing the cryptographic hash of a file.
4434 * Invoking guix import:: Importing package definitions.
4435 * Invoking guix refresh:: Updating package definitions.
4436 * Invoking guix lint:: Finding errors in package definitions.
4437 * Invoking guix size:: Profiling disk usage.
4438 * Invoking guix graph:: Visualizing the graph of packages.
4439 * Invoking guix environment:: Setting up development environments.
4440 * Invoking guix publish:: Sharing substitutes.
4441 * Invoking guix challenge:: Challenging substitute servers.
4442 * Invoking guix container:: Process isolation.
4445 @node Invoking guix build
4446 @section Invoking @command{guix build}
4448 @cindex package building
4449 @cindex @command{guix build}
4450 The @command{guix build} command builds packages or derivations and
4451 their dependencies, and prints the resulting store paths. Note that it
4452 does not modify the user's profile---this is the job of the
4453 @command{guix package} command (@pxref{Invoking guix package}). Thus,
4454 it is mainly useful for distribution developers.
4456 The general syntax is:
4459 guix build @var{options} @var{package-or-derivation}@dots{}
4462 As an example, the following command builds the latest versions of Emacs
4463 and of Guile, displays their build logs, and finally displays the
4464 resulting directories:
4467 guix build emacs guile
4470 Similarly, the following command builds all the available packages:
4473 guix build --quiet --keep-going \
4474 `guix package -A | cut -f1,2 --output-delimiter=@@`
4477 @var{package-or-derivation} may be either the name of a package found in
4478 the software distribution such as @code{coreutils} or
4479 @code{coreutils-8.20}, or a derivation such as
4480 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
4481 package with the corresponding name (and optionally version) is searched
4482 for among the GNU distribution modules (@pxref{Package Modules}).
4484 Alternatively, the @code{--expression} option may be used to specify a
4485 Scheme expression that evaluates to a package; this is useful when
4486 disambiguating among several same-named packages or package variants is
4489 There may be zero or more @var{options}. The available options are
4490 described in the subsections below.
4493 * Common Build Options:: Build options for most commands.
4494 * Package Transformation Options:: Creating variants of packages.
4495 * Additional Build Options:: Options specific to 'guix build'.
4498 @node Common Build Options
4499 @subsection Common Build Options
4501 A number of options that control the build process are common to
4502 @command{guix build} and other commands that can spawn builds, such as
4503 @command{guix package} or @command{guix archive}. These are the
4508 @item --load-path=@var{directory}
4509 @itemx -L @var{directory}
4510 Add @var{directory} to the front of the package module search path
4511 (@pxref{Package Modules}).
4513 This allows users to define their own packages and make them visible to
4514 the command-line tools.
4518 Keep the build tree of failed builds. Thus, if a build fails, its build
4519 tree is kept under @file{/tmp}, in a directory whose name is shown at
4520 the end of the build log. This is useful when debugging build issues.
4524 Keep going when some of the derivations fail to build; return only once
4525 all the builds have either completed or failed.
4527 The default behavior is to stop as soon as one of the specified
4528 derivations has failed.
4532 Do not build the derivations.
4535 When substituting a pre-built binary fails, fall back to building
4538 @item --substitute-urls=@var{urls}
4539 @anchor{client-substitute-urls}
4540 Consider @var{urls} the whitespace-separated list of substitute source
4541 URLs, overriding the default list of URLs of @command{guix-daemon}
4542 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
4544 This means that substitutes may be downloaded from @var{urls}, provided
4545 they are signed by a key authorized by the system administrator
4546 (@pxref{Substitutes}).
4548 When @var{urls} is the empty string, substitutes are effectively
4551 @item --no-substitutes
4552 Do not use substitutes for build products. That is, always build things
4553 locally instead of allowing downloads of pre-built binaries
4554 (@pxref{Substitutes}).
4557 Do not ``graft'' packages. In practice, this means that package updates
4558 available as grafts are not applied. @xref{Security Updates}, for more
4559 information on grafts.
4561 @item --rounds=@var{n}
4562 Build each derivation @var{n} times in a row, and raise an error if
4563 consecutive build results are not bit-for-bit identical.
4565 This is a useful way to detect non-deterministic builds processes.
4566 Non-deterministic build processes are a problem because they make it
4567 practically impossible for users to @emph{verify} whether third-party
4568 binaries are genuine. @xref{Invoking guix challenge}, for more.
4570 Note that, currently, the differing build results are not kept around,
4571 so you will have to manually investigate in case of an error---e.g., by
4572 stashing one of the build results with @code{guix archive --export}
4573 (@pxref{Invoking guix archive}), then rebuilding, and finally comparing
4576 @item --no-build-hook
4577 Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
4578 (@pxref{Daemon Offload Setup}). That is, always build things locally
4579 instead of offloading builds to remote machines.
4581 @item --max-silent-time=@var{seconds}
4582 When the build or substitution process remains silent for more than
4583 @var{seconds}, terminate it and report a build failure.
4585 @item --timeout=@var{seconds}
4586 Likewise, when the build or substitution process lasts for more than
4587 @var{seconds}, terminate it and report a build failure.
4589 By default there is no timeout. This behavior can be restored with
4592 @item --verbosity=@var{level}
4593 Use the given verbosity level. @var{level} must be an integer between 0
4594 and 5; higher means more verbose output. Setting a level of 4 or more
4595 may be helpful when debugging setup issues with the build daemon.
4597 @item --cores=@var{n}
4599 Allow the use of up to @var{n} CPU cores for the build. The special
4600 value @code{0} means to use as many CPU cores as available.
4602 @item --max-jobs=@var{n}
4604 Allow at most @var{n} build jobs in parallel. @xref{Invoking
4605 guix-daemon, @code{--max-jobs}}, for details about this option and the
4606 equivalent @command{guix-daemon} option.
4610 Behind the scenes, @command{guix build} is essentially an interface to
4611 the @code{package-derivation} procedure of the @code{(guix packages)}
4612 module, and to the @code{build-derivations} procedure of the @code{(guix
4613 derivations)} module.
4615 In addition to options explicitly passed on the command line,
4616 @command{guix build} and other @command{guix} commands that support
4617 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
4619 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
4620 Users can define this variable to a list of command line options that
4621 will automatically be used by @command{guix build} and other
4622 @command{guix} commands that can perform builds, as in the example
4626 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
4629 These options are parsed independently, and the result is appended to
4630 the parsed command-line options.
4634 @node Package Transformation Options
4635 @subsection Package Transformation Options
4637 @cindex package variants
4638 Another set of command-line options supported by @command{guix build}
4639 and also @command{guix package} are @dfn{package transformation
4640 options}. These are options that make it possible to define @dfn{package
4641 variants}---for instance, packages built from different source code.
4642 This is a convenient way to create customized packages on the fly
4643 without having to type in the definitions of package variants
4644 (@pxref{Defining Packages}).
4648 @item --with-source=@var{source}
4649 Use @var{source} as the source of the corresponding package.
4650 @var{source} must be a file name or a URL, as for @command{guix
4651 download} (@pxref{Invoking guix download}).
4653 The ``corresponding package'' is taken to be the one specified on the
4654 command line the name of which matches the base of @var{source}---e.g.,
4655 if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4656 package is @code{guile}. Likewise, the version string is inferred from
4657 @var{source}; in the previous example, it is @code{2.0.10}.
4659 This option allows users to try out versions of packages other than the
4660 one provided by the distribution. The example below downloads
4661 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4662 the @code{ed} package:
4665 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4668 As a developer, @code{--with-source} makes it easy to test release
4672 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4675 @dots{} or to build from a checkout in a pristine environment:
4678 $ git clone git://git.sv.gnu.org/guix.git
4679 $ guix build guix --with-source=./guix
4682 @item --with-input=@var{package}=@var{replacement}
4683 Replace dependency on @var{package} by a dependency on
4684 @var{replacement}. @var{package} must be a package name, and
4685 @var{replacement} must be a package specification such as @code{guile}
4686 or @code{guile@@1.8}.
4688 For instance, the following command builds Guix, but replaces its
4689 dependency on the current stable version of Guile with a dependency on
4690 the development version of Guile, @code{guile-next}:
4693 guix build --with-input=guile=guile-next guix
4696 This is a recursive, deep replacement. So in this example, both
4697 @code{guix} and its dependency @code{guile-json} (which also depends on
4698 @code{guile}) get rebuilt against @code{guile-next}.
4700 This is implemented using the @code{package-input-rewriting} Scheme
4701 procedure (@pxref{Defining Packages, @code{package-input-rewriting}}).
4703 @item --with-graft=@var{package}=@var{replacement}
4704 This is similar to @code{--with-input} but with an important difference:
4705 instead of rebuilding all the dependency chain, @var{replacement} is
4706 built and then @dfn{grafted} onto the binaries that were initially
4707 referring to @var{package}. @xref{Security Updates}, for more
4708 information on grafts.
4710 For example, the command below grafts version 3.5.4 of GnuTLS onto Wget
4711 and all its dependencies, replacing references to the version of GnuTLS
4712 they currently refer to:
4715 guix build --with-graft=gnutls=gnutls@@3.5.4 wget
4718 This has the advantage of being much faster than rebuilding everything.
4719 But there is a caveat: it works if and only if @var{package} and
4720 @var{replacement} are strictly compatible---for example, if they provide
4721 a library, the application binary interface (ABI) of those libraries
4722 must be compatible. If @var{replacement} is somehow incompatible with
4723 @var{package}, then the resulting package may be unusable. Use with
4728 @node Additional Build Options
4729 @subsection Additional Build Options
4731 The command-line options presented below are specific to @command{guix
4738 Build quietly, without displaying the build log. Upon completion, the
4739 build log is kept in @file{/var} (or similar) and can always be
4740 retrieved using the @option{--log-file} option.
4742 @item --file=@var{file}
4743 @itemx -f @var{file}
4745 Build the package or derivation that the code within @var{file}
4748 As an example, @var{file} might contain a package definition like this
4749 (@pxref{Defining Packages}):
4752 @verbatiminclude package-hello.scm
4755 @item --expression=@var{expr}
4756 @itemx -e @var{expr}
4757 Build the package or derivation @var{expr} evaluates to.
4759 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4760 guile-1.8)}, which unambiguously designates this specific variant of
4761 version 1.8 of Guile.
4763 Alternatively, @var{expr} may be a G-expression, in which case it is used
4764 as a build program passed to @code{gexp->derivation}
4765 (@pxref{G-Expressions}).
4767 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4768 (@pxref{The Store Monad}). The procedure must return a derivation as a
4769 monadic value, which is then passed through @code{run-with-store}.
4773 Build the source derivations of the packages, rather than the packages
4776 For instance, @code{guix build -S gcc} returns something like
4777 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
4780 The returned source tarball is the result of applying any patches and
4781 code snippets specified in the package @code{origin} (@pxref{Defining
4785 Fetch and return the source of @var{package-or-derivation} and all their
4786 dependencies, recursively. This is a handy way to obtain a local copy
4787 of all the source code needed to build @var{packages}, allowing you to
4788 eventually build them even without network access. It is an extension
4789 of the @code{--source} option and can accept one of the following
4790 optional argument values:
4794 This value causes the @code{--sources} option to behave in the same way
4795 as the @code{--source} option.
4798 Build the source derivations of all packages, including any source that
4799 might be listed as @code{inputs}. This is the default value.
4802 $ guix build --sources tzdata
4803 The following derivations will be built:
4804 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4805 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4809 Build the source derivations of all packages, as well of all transitive
4810 inputs to the packages. This can be used e.g. to
4811 prefetch package source for later offline building.
4814 $ guix build --sources=transitive tzdata
4815 The following derivations will be built:
4816 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4817 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4818 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4819 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4820 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4821 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4827 @item --system=@var{system}
4828 @itemx -s @var{system}
4829 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4830 the system type of the build host.
4832 An example use of this is on Linux-based systems, which can emulate
4833 different personalities. For instance, passing
4834 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4835 to build packages in a complete 32-bit environment.
4837 @item --target=@var{triplet}
4838 @cindex cross-compilation
4839 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4840 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4841 configuration triplets,, configure, GNU Configure and Build System}).
4843 @anchor{build-check}
4845 @cindex determinism, checking
4846 @cindex reproducibility, checking
4847 Rebuild @var{package-or-derivation}, which are already available in the
4848 store, and raise an error if the build results are not bit-for-bit
4851 This mechanism allows you to check whether previously installed
4852 substitutes are genuine (@pxref{Substitutes}), or whether the build result
4853 of a package is deterministic. @xref{Invoking guix challenge}, for more
4854 background information and tools.
4856 When used in conjunction with @option{--keep-failed}, the differing
4857 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
4858 This makes it easy to look for differences between the two results.
4862 Return the derivation paths, not the output paths, of the given
4865 @item --root=@var{file}
4866 @itemx -r @var{file}
4867 Make @var{file} a symlink to the result, and register it as a garbage
4871 Return the build log file names or URLs for the given
4872 @var{package-or-derivation}, or raise an error if build logs are
4875 This works regardless of how packages or derivations are specified. For
4876 instance, the following invocations are equivalent:
4879 guix build --log-file `guix build -d guile`
4880 guix build --log-file `guix build guile`
4881 guix build --log-file guile
4882 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4885 If a log is unavailable locally, and unless @code{--no-substitutes} is
4886 passed, the command looks for a corresponding log on one of the
4887 substitute servers (as specified with @code{--substitute-urls}.)
4889 So for instance, imagine you want to see the build log of GDB on MIPS,
4890 but you are actually on an @code{x86_64} machine:
4893 $ guix build --log-file gdb -s mips64el-linux
4894 https://hydra.gnu.org/log/@dots{}-gdb-7.10
4897 You can freely access a huge library of build logs!
4901 @node Invoking guix edit
4902 @section Invoking @command{guix edit}
4904 @cindex @command{guix edit}
4905 @cindex package definition, editing
4906 So many packages, so many source files! The @command{guix edit} command
4907 facilitates the life of users and packagers by pointing their editor at
4908 the source file containing the definition of the specified packages.
4912 guix edit gcc@@4.9 vim
4916 launches the program specified in the @code{VISUAL} or in the
4917 @code{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3
4920 If you are using a Guix Git checkout (@pxref{Building from Git}), or
4921 have created your own packages on @code{GUIX_PACKAGE_PATH}
4922 (@pxref{Defining Packages}), you will be able to edit the package
4923 recipes. Otherwise, you will be able to examine the read-only recipes
4924 for packages currently in the store.
4926 If you are using Emacs, note that the Emacs user interface provides the
4927 @kbd{M-x guix-edit} command and a similar functionality in the ``package
4928 info'' and ``package list'' buffers created by the @kbd{M-x
4929 guix-search-by-name} and similar commands (@pxref{Emacs Commands}).
4932 @node Invoking guix download
4933 @section Invoking @command{guix download}
4935 @cindex @command{guix download}
4936 @cindex downloading package sources
4937 When writing a package definition, developers typically need to download
4938 a source tarball, compute its SHA256 hash, and write that
4939 hash in the package definition (@pxref{Defining Packages}). The
4940 @command{guix download} tool helps with this task: it downloads a file
4941 from the given URI, adds it to the store, and prints both its file name
4942 in the store and its SHA256 hash.
4944 The fact that the downloaded file is added to the store saves bandwidth:
4945 when the developer eventually tries to build the newly defined package
4946 with @command{guix build}, the source tarball will not have to be
4947 downloaded again because it is already in the store. It is also a
4948 convenient way to temporarily stash files, which may be deleted
4949 eventually (@pxref{Invoking guix gc}).
4951 The @command{guix download} command supports the same URIs as used in
4952 package definitions. In particular, it supports @code{mirror://} URIs.
4953 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4954 Guile bindings for GnuTLS are available in the user's environment; when
4955 they are not available, an error is raised. @xref{Guile Preparations,
4956 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4957 GnuTLS-Guile}, for more information.
4959 @command{guix download} verifies HTTPS server certificates by loading
4960 the certificates of X.509 authorities from the directory pointed to by
4961 the @code{SSL_CERT_DIR} environment variable (@pxref{X.509
4962 Certificates}), unless @option{--no-check-certificate} is used.
4964 The following options are available:
4967 @item --format=@var{fmt}
4969 Write the hash in the format specified by @var{fmt}. For more
4970 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4972 @item --no-check-certificate
4973 Do not validate the X.509 certificates of HTTPS servers.
4975 When using this option, you have @emph{absolutely no guarantee} that you
4976 are communicating with the authentic server responsible for the given
4977 URL, which makes you vulnerable to ``man-in-the-middle'' attacks.
4979 @item --output=@var{file}
4980 @itemx -o @var{file}
4981 Save the downloaded file to @var{file} instead of adding it to the
4985 @node Invoking guix hash
4986 @section Invoking @command{guix hash}
4988 @cindex @command{guix hash}
4989 The @command{guix hash} command computes the SHA256 hash of a file.
4990 It is primarily a convenience tool for anyone contributing to the
4991 distribution: it computes the cryptographic hash of a file, which can be
4992 used in the definition of a package (@pxref{Defining Packages}).
4994 The general syntax is:
4997 guix hash @var{option} @var{file}
5000 When @var{file} is @code{-} (a hyphen), @command{guix hash} computes the
5001 hash of data read from standard input. @command{guix hash} has the
5006 @item --format=@var{fmt}
5008 Write the hash in the format specified by @var{fmt}.
5010 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
5011 (@code{hex} and @code{hexadecimal} can be used as well).
5013 If the @option{--format} option is not specified, @command{guix hash}
5014 will output the hash in @code{nix-base32}. This representation is used
5015 in the definitions of packages.
5019 Compute the hash on @var{file} recursively.
5021 In this case, the hash is computed on an archive containing @var{file},
5022 including its children if it is a directory. Some of the metadata of
5023 @var{file} is part of the archive; for instance, when @var{file} is a
5024 regular file, the hash is different depending on whether @var{file} is
5025 executable or not. Metadata such as time stamps has no impact on the
5026 hash (@pxref{Invoking guix archive}).
5027 @c FIXME: Replace xref above with xref to an ``Archive'' section when
5032 When combined with @option{--recursive}, exclude version control system
5033 directories (@file{.bzr}, @file{.git}, @file{.hg}, etc.)
5036 As an example, here is how you would compute the hash of a Git checkout,
5037 which is useful when using the @code{git-fetch} method (@pxref{origin
5041 $ git clone http://example.org/foo.git
5047 @node Invoking guix import
5048 @section Invoking @command{guix import}
5050 @cindex importing packages
5051 @cindex package import
5052 @cindex package conversion
5053 @cindex Invoking @command{guix import}
5054 The @command{guix import} command is useful for people who would like to
5055 add a package to the distribution with as little work as
5056 possible---a legitimate demand. The command knows of a few
5057 repositories from which it can ``import'' package metadata. The result
5058 is a package definition, or a template thereof, in the format we know
5059 (@pxref{Defining Packages}).
5061 The general syntax is:
5064 guix import @var{importer} @var{options}@dots{}
5067 @var{importer} specifies the source from which to import package
5068 metadata, and @var{options} specifies a package identifier and other
5069 options specific to @var{importer}. Currently, the available
5074 Import metadata for the given GNU package. This provides a template
5075 for the latest version of that GNU package, including the hash of its
5076 source tarball, and its canonical synopsis and description.
5078 Additional information such as the package dependencies and its
5079 license needs to be figured out manually.
5081 For example, the following command returns a package definition for
5085 guix import gnu hello
5088 Specific command-line options are:
5091 @item --key-download=@var{policy}
5092 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
5093 keys when verifying the package signature. @xref{Invoking guix
5094 refresh, @code{--key-download}}.
5099 Import metadata from the @uref{https://pypi.python.org/, Python Package
5100 Index}@footnote{This functionality requires Guile-JSON to be installed.
5101 @xref{Requirements}.}. Information is taken from the JSON-formatted
5102 description available at @code{pypi.python.org} and usually includes all
5103 the relevant information, including package dependencies. For maximum
5104 efficiency, it is recommended to install the @command{unzip} utility, so
5105 that the importer can unzip Python wheels and gather data from them.
5107 The command below imports metadata for the @code{itsdangerous} Python
5111 guix import pypi itsdangerous
5116 Import metadata from @uref{https://rubygems.org/,
5117 RubyGems}@footnote{This functionality requires Guile-JSON to be
5118 installed. @xref{Requirements}.}. Information is taken from the
5119 JSON-formatted description available at @code{rubygems.org} and includes
5120 most relevant information, including runtime dependencies. There are
5121 some caveats, however. The metadata doesn't distinguish between
5122 synopses and descriptions, so the same string is used for both fields.
5123 Additionally, the details of non-Ruby dependencies required to build
5124 native extensions is unavailable and left as an exercise to the
5127 The command below imports metadata for the @code{rails} Ruby package:
5130 guix import gem rails
5135 Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
5136 functionality requires Guile-JSON to be installed.
5137 @xref{Requirements}.}.
5138 Information is taken from the JSON-formatted metadata provided through
5139 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
5140 relevant information, such as module dependencies. License information
5141 should be checked closely. If Perl is available in the store, then the
5142 @code{corelist} utility will be used to filter core modules out of the
5143 list of dependencies.
5145 The command command below imports metadata for the @code{Acme::Boolean}
5149 guix import cpan Acme::Boolean
5154 @cindex Bioconductor
5155 Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
5156 central repository for the @uref{http://r-project.org, GNU@tie{}R
5157 statistical and graphical environment}.
5159 Information is extracted from the @code{DESCRIPTION} file of the package.
5161 The command command below imports metadata for the @code{Cairo}
5165 guix import cran Cairo
5168 When @code{--recursive} is added, the importer will traverse the
5169 dependency graph of the given upstream package recursively and generate
5170 package expressions for all those packages that are not yet in Guix.
5172 When @code{--archive=bioconductor} is added, metadata is imported from
5173 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
5174 packages for for the analysis and comprehension of high-throughput
5175 genomic data in bioinformatics.
5177 Information is extracted from the @code{DESCRIPTION} file of a package
5178 published on the web interface of the Bioconductor SVN repository.
5180 The command below imports metadata for the @code{GenomicRanges}
5184 guix import cran --archive=bioconductor GenomicRanges
5188 Import metadata from a local copy of the source of the
5189 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
5190 relies on the @command{nix-instantiate} command of
5191 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
5192 typically written in a mixture of Nix-language and Bash code. This
5193 command only imports the high-level package structure that is written in
5194 the Nix language. It normally includes all the basic fields of a
5197 When importing a GNU package, the synopsis and descriptions are replaced
5198 by their canonical upstream variant.
5200 Usually, you will first need to do:
5203 export NIX_REMOTE=daemon
5207 so that @command{nix-instantiate} does not try to open the Nix database.
5209 As an example, the command below imports the package definition of
5210 LibreOffice (more precisely, it imports the definition of the package
5211 bound to the @code{libreoffice} top-level attribute):
5214 guix import nix ~/path/to/nixpkgs libreoffice
5219 Import metadata from the Haskell community's central package archive
5220 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
5221 Cabal files and includes all the relevant information, including package
5224 Specific command-line options are:
5229 Read a Cabal file from standard input.
5230 @item --no-test-dependencies
5232 Do not include dependencies required only by the test suites.
5233 @item --cabal-environment=@var{alist}
5234 @itemx -e @var{alist}
5235 @var{alist} is a Scheme alist defining the environment in which the
5236 Cabal conditionals are evaluated. The accepted keys are: @code{os},
5237 @code{arch}, @code{impl} and a string representing the name of a flag.
5238 The value associated with a flag has to be either the symbol
5239 @code{true} or @code{false}. The value associated with other keys
5240 has to conform to the Cabal file format definition. The default value
5241 associated with the keys @code{os}, @code{arch} and @code{impl} is
5242 @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
5245 The command below imports metadata for the latest version of the
5246 @code{HTTP} Haskell package without including test dependencies and
5247 specifying the value of the flag @samp{network-uri} as @code{false}:
5250 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
5253 A specific package version may optionally be specified by following the
5254 package name by an at-sign and a version number as in the following example:
5257 guix import hackage mtl@@2.1.3.1
5262 Import metadata from an Emacs Lisp Package Archive (ELPA) package
5263 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
5265 Specific command-line options are:
5268 @item --archive=@var{repo}
5269 @itemx -a @var{repo}
5270 @var{repo} identifies the archive repository from which to retrieve the
5271 information. Currently the supported repositories and their identifiers
5275 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
5276 identifier. This is the default.
5278 Packages from @code{elpa.gnu.org} are signed with one of the keys
5279 contained in the GnuPG keyring at
5280 @file{share/emacs/25.1/etc/package-keyring.gpg} (or similar) in the
5281 @code{emacs} package (@pxref{Package Installation, ELPA package
5282 signatures,, emacs, The GNU Emacs Manual}).
5285 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
5286 @code{melpa-stable} identifier.
5289 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
5296 Import metadata from the crates.io Rust package repository
5297 @uref{https://crates.io, crates.io}.
5300 The structure of the @command{guix import} code is modular. It would be
5301 useful to have more importers for other package formats, and your help
5302 is welcome here (@pxref{Contributing}).
5304 @node Invoking guix refresh
5305 @section Invoking @command{guix refresh}
5307 @cindex @command {guix refresh}
5308 The primary audience of the @command{guix refresh} command is developers
5309 of the GNU software distribution. By default, it reports any packages
5310 provided by the distribution that are outdated compared to the latest
5311 upstream version, like this:
5315 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
5316 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
5319 Alternately, one can specify packages to consider, in which case a
5320 warning is emitted for packages that lack an updater:
5323 $ guix refresh coreutils guile guile-ssh
5324 gnu/packages/ssh.scm:205:2: warning: no updater for guile-ssh
5325 gnu/packages/guile.scm:136:12: guile would be upgraded from 2.0.12 to 2.0.13
5328 @command{guix refresh} browses the upstream repository of each package and determines
5329 the highest version number of the releases therein. The command
5330 knows how to update specific types of packages: GNU packages, ELPA
5331 packages, etc.---see the documentation for @option{--type} below. There
5332 are many packages, though, for which it lacks a method to determine
5333 whether a new upstream release is available. However, the mechanism is
5334 extensible, so feel free to get in touch with us to add a new method!
5336 When passed @code{--update}, it modifies distribution source files to
5337 update the version numbers and source tarball hashes of those package
5338 recipes (@pxref{Defining Packages}). This is achieved by downloading
5339 each package's latest source tarball and its associated OpenPGP
5340 signature, authenticating the downloaded tarball against its signature
5341 using @command{gpg}, and finally computing its hash. When the public
5342 key used to sign the tarball is missing from the user's keyring, an
5343 attempt is made to automatically retrieve it from a public key server;
5344 when this is successful, the key is added to the user's keyring; otherwise,
5345 @command{guix refresh} reports an error.
5347 The following options are supported:
5351 @item --expression=@var{expr}
5352 @itemx -e @var{expr}
5353 Consider the package @var{expr} evaluates to.
5355 This is useful to precisely refer to a package, as in this example:
5358 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
5361 This command lists the dependents of the ``final'' libc (essentially all
5366 Update distribution source files (package recipes) in place. This is
5367 usually run from a checkout of the Guix source tree (@pxref{Running
5368 Guix Before It Is Installed}):
5371 $ ./pre-inst-env guix refresh -s non-core -u
5374 @xref{Defining Packages}, for more information on package definitions.
5376 @item --select=[@var{subset}]
5377 @itemx -s @var{subset}
5378 Select all the packages in @var{subset}, one of @code{core} or
5381 The @code{core} subset refers to all the packages at the core of the
5382 distribution---i.e., packages that are used to build ``everything
5383 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
5384 changing one of these packages in the distribution entails a rebuild of
5385 all the others. Thus, such updates are an inconvenience to users in
5386 terms of build time or bandwidth used to achieve the upgrade.
5388 The @code{non-core} subset refers to the remaining packages. It is
5389 typically useful in cases where an update of the core packages would be
5392 @item --type=@var{updater}
5393 @itemx -t @var{updater}
5394 Select only packages handled by @var{updater} (may be a comma-separated
5395 list of updaters). Currently, @var{updater} may be one of:
5399 the updater for GNU packages;
5401 the updater for GNOME packages;
5403 the updater for KDE packages;
5405 the updater for X.org packages;
5407 the updater for packages hosted on kernel.org;
5409 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
5411 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
5413 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
5415 the updater for @uref{http://www.cpan.org/, CPAN} packages;
5417 the updater for @uref{https://pypi.python.org, PyPI} packages.
5419 the updater for @uref{https://rubygems.org, RubyGems} packages.
5421 the updater for @uref{https://github.com, GitHub} packages.
5423 the updater for @uref{https://hackage.haskell.org, Hackage} packages.
5425 the updater for @uref{https://crates.io, Crates} packages.
5428 For instance, the following command only checks for updates of Emacs
5429 packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:
5432 $ guix refresh --type=elpa,cran
5433 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
5434 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
5439 In addition, @command{guix refresh} can be passed one or more package
5440 names, as in this example:
5443 $ ./pre-inst-env guix refresh -u emacs idutils gcc@@4.8
5447 The command above specifically updates the @code{emacs} and
5448 @code{idutils} packages. The @code{--select} option would have no
5449 effect in this case.
5451 When considering whether to upgrade a package, it is sometimes
5452 convenient to know which packages would be affected by the upgrade and
5453 should be checked for compatibility. For this the following option may
5454 be used when passing @command{guix refresh} one or more package names:
5458 @item --list-updaters
5460 List available updaters and exit (see @option{--type} above.)
5462 For each updater, display the fraction of packages it covers; at the
5463 end, display the fraction of packages covered by all these updaters.
5465 @item --list-dependent
5467 List top-level dependent packages that would need to be rebuilt as a
5468 result of upgrading one or more packages.
5472 Be aware that the @code{--list-dependent} option only
5473 @emph{approximates} the rebuilds that would be required as a result of
5474 an upgrade. More rebuilds might be required under some circumstances.
5477 $ guix refresh --list-dependent flex
5478 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
5479 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
5482 The command above lists a set of packages that could be built to check
5483 for compatibility with an upgraded @code{flex} package.
5485 The following options can be used to customize GnuPG operation:
5489 @item --gpg=@var{command}
5490 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
5491 for in @code{$PATH}.
5493 @item --key-download=@var{policy}
5494 Handle missing OpenPGP keys according to @var{policy}, which may be one
5499 Always download missing OpenPGP keys from the key server, and add them
5500 to the user's GnuPG keyring.
5503 Never try to download missing OpenPGP keys. Instead just bail out.
5506 When a package signed with an unknown OpenPGP key is encountered, ask
5507 the user whether to download it or not. This is the default behavior.
5510 @item --key-server=@var{host}
5511 Use @var{host} as the OpenPGP key server when importing a public key.
5515 The @code{github} updater uses the
5516 @uref{https://developer.github.com/v3/, GitHub API} to query for new
5517 releases. When used repeatedly e.g. when refreshing all packages,
5518 GitHub will eventually refuse to answer any further API requests. By
5519 default 60 API requests per hour are allowed, and a full refresh on all
5520 GitHub packages in Guix requires more than this. Authentication with
5521 GitHub through the use of an API token alleviates these limits. To use
5522 an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
5523 token procured from @uref{https://github.com/settings/tokens} or
5527 @node Invoking guix lint
5528 @section Invoking @command{guix lint}
5530 @cindex @command{guix lint}
5531 @cindex package, checking for errors
5532 The @command{guix lint} command is meant to help package developers avoid
5533 common errors and use a consistent style. It runs a number of checks on
5534 a given set of packages in order to find common mistakes in their
5535 definitions. Available @dfn{checkers} include (see
5536 @code{--list-checkers} for a complete list):
5541 Validate certain typographical and stylistic rules about package
5542 descriptions and synopses.
5544 @item inputs-should-be-native
5545 Identify inputs that should most likely be native inputs.
5550 @itemx source-file-name
5551 Probe @code{home-page} and @code{source} URLs and report those that are
5552 invalid. Suggest a @code{mirror://} URL when applicable. Check that
5553 the source file name is meaningful, e.g. is not
5554 just a version number or ``git-checkout'', without a declared
5555 @code{file-name} (@pxref{origin Reference}).
5558 @cindex security vulnerabilities
5559 @cindex CVE, Common Vulnerabilities and Exposures
5560 Report known vulnerabilities found in the Common Vulnerabilities and
5561 Exposures (CVE) databases of the current and past year
5562 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
5565 To view information about a particular vulnerability, visit pages such as:
5569 @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD}
5571 @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD}
5575 where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g.,
5576 @code{CVE-2015-7554}.
5578 Package developers can specify in package recipes the
5579 @uref{https://nvd.nist.gov/cpe.cfm,Common Platform Enumeration (CPE)}
5580 name and version of the package when they differ from the name that Guix
5581 uses, as in this example:
5587 ;; CPE calls this package "grub2".
5588 (properties '((cpe-name . "grub2"))))
5592 Warn about obvious source code formatting issues: trailing white space,
5593 use of tabulations, etc.
5596 The general syntax is:
5599 guix lint @var{options} @var{package}@dots{}
5602 If no package is given on the command line, then all packages are checked.
5603 The @var{options} may be zero or more of the following:
5606 @item --list-checkers
5608 List and describe all the available checkers that will be run on packages
5613 Only enable the checkers specified in a comma-separated list using the
5614 names returned by @code{--list-checkers}.
5618 @node Invoking guix size
5619 @section Invoking @command{guix size}
5622 @cindex package size
5624 @cindex @command{guix size}
5625 The @command{guix size} command helps package developers profile the
5626 disk usage of packages. It is easy to overlook the impact of an
5627 additional dependency added to a package, or the impact of using a
5628 single output for a package that could easily be split (@pxref{Packages
5629 with Multiple Outputs}). Such are the typical issues that
5630 @command{guix size} can highlight.
5632 The command can be passed a package specification such as @code{gcc-4.8}
5633 or @code{guile:debug}, or a file name in the store. Consider this
5637 $ guix size coreutils
5638 store item total self
5639 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
5640 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
5641 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
5642 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
5643 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
5644 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
5648 The store items listed here constitute the @dfn{transitive closure} of
5649 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
5650 would be returned by:
5653 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
5656 Here the output shows three columns next to store items. The first column,
5657 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
5658 the store item---that is, its own size plus the size of all its
5659 dependencies. The next column, labeled ``self'', shows the size of the
5660 item itself. The last column shows the ratio of the size of the item
5661 itself to the space occupied by all the items listed here.
5663 In this example, we see that the closure of Coreutils weighs in at
5664 70@tie{}MiB, half of which is taken by libc. (That libc represents a
5665 large fraction of the closure is not a problem @i{per se} because it is
5666 always available on the system anyway.)
5668 When the package passed to @command{guix size} is available in the
5669 store, @command{guix size} queries the daemon to determine its
5670 dependencies, and measures its size in the store, similar to @command{du
5671 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
5674 When the given package is @emph{not} in the store, @command{guix size}
5675 reports information based on the available substitutes
5676 (@pxref{Substitutes}). This makes it possible it to profile disk usage of
5677 store items that are not even on disk, only available remotely.
5679 You can also specify several package names:
5682 $ guix size coreutils grep sed bash
5683 store item total self
5684 /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4%
5685 /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8%
5686 /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6%
5687 /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2%
5693 In this example we see that the combination of the four packages takes
5694 102.3@tie{}MiB in total, which is much less than the sum of each closure
5695 since they have a lot of dependencies in common.
5697 The available options are:
5701 @item --substitute-urls=@var{urls}
5702 Use substitute information from @var{urls}.
5703 @xref{client-substitute-urls, the same option for @code{guix build}}.
5705 @item --map-file=@var{file}
5706 Write a graphical map of disk usage in PNG format to @var{file}.
5708 For the example above, the map looks like this:
5710 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
5711 produced by @command{guix size}}
5713 This option requires that
5714 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
5715 installed and visible in Guile's module search path. When that is not
5716 the case, @command{guix size} fails as it tries to load it.
5718 @item --system=@var{system}
5719 @itemx -s @var{system}
5720 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
5724 @node Invoking guix graph
5725 @section Invoking @command{guix graph}
5728 @cindex @command{guix graph}
5729 @cindex package dependencies
5730 Packages and their dependencies form a @dfn{graph}, specifically a
5731 directed acyclic graph (DAG). It can quickly become difficult to have a
5732 mental model of the package DAG, so the @command{guix graph} command
5733 provides a visual representation of the DAG. By default,
5734 @command{guix graph} emits a DAG representation in the input format of
5735 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
5736 directly to the @command{dot} command of Graphviz. It can also emit an
5737 HTML page with embedded JavaScript code to display a ``chord diagram''
5738 in a Web browser, using the @uref{https://d3js.org/, d3.js} library.
5739 The general syntax is:
5742 guix graph @var{options} @var{package}@dots{}
5745 For example, the following command generates a PDF file representing the
5746 package DAG for the GNU@tie{}Core Utilities, showing its build-time
5750 guix graph coreutils | dot -Tpdf > dag.pdf
5753 The output looks like this:
5755 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
5757 Nice little graph, no?
5759 But there is more than one graph! The one above is concise: it is the
5760 graph of package objects, omitting implicit inputs such as GCC, libc,
5761 grep, etc. It is often useful to have such a concise graph, but
5762 sometimes one may want to see more details. @command{guix graph} supports
5763 several types of graphs, allowing you to choose the level of detail:
5767 This is the default type used in the example above. It shows the DAG of
5768 package objects, excluding implicit dependencies. It is concise, but
5769 filters out many details.
5772 This is the package DAG, @emph{including} implicit inputs.
5774 For instance, the following command:
5777 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
5780 ... yields this bigger graph:
5782 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
5784 At the bottom of the graph, we see all the implicit inputs of
5785 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
5787 Now, note that the dependencies of these implicit inputs---that is, the
5788 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
5789 here, for conciseness.
5792 Similar to @code{bag-emerged}, but this time including all the bootstrap
5795 @item bag-with-origins
5796 Similar to @code{bag}, but also showing origins and their dependencies.
5799 This is the most detailed representation: It shows the DAG of
5800 derivations (@pxref{Derivations}) and plain store items. Compared to
5801 the above representation, many additional nodes are visible, including
5802 build scripts, patches, Guile modules, etc.
5804 For this type of graph, it is also possible to pass a @file{.drv} file
5805 name instead of a package name, as in:
5808 guix graph -t derivation `guix system build -d my-config.scm`
5812 All the types above correspond to @emph{build-time dependencies}. The
5813 following graph type represents the @emph{run-time dependencies}:
5817 This is the graph of @dfn{references} of a package output, as returned
5818 by @command{guix gc --references} (@pxref{Invoking guix gc}).
5820 If the given package output is not available in the store, @command{guix
5821 graph} attempts to obtain dependency information from substitutes.
5823 Here you can also pass a store file name instead of a package name. For
5824 example, the command below produces the reference graph of your profile
5825 (which can be big!):
5828 guix graph -t references `readlink -f ~/.guix-profile`
5832 This is the graph of the @dfn{referrers} of a store item, as returned by
5833 @command{guix gc --referrers} (@pxref{Invoking guix gc}).
5835 This relies exclusively on local information from your store. For
5836 instance, let us suppose that the current Inkscape is available in 10
5837 profiles on your machine; @command{guix graph -t referrers inkscape}
5838 will show a graph rooted at Inkscape and with those 10 profiles linked
5841 It can help determine what is preventing a store item from being garbage
5846 The available options are the following:
5849 @item --type=@var{type}
5850 @itemx -t @var{type}
5851 Produce a graph output of @var{type}, where @var{type} must be one of
5852 the values listed above.
5855 List the supported graph types.
5857 @item --backend=@var{backend}
5858 @itemx -b @var{backend}
5859 Produce a graph using the selected @var{backend}.
5861 @item --list-backends
5862 List the supported graph backends.
5864 Currently, the available backends are Graphviz and d3.js.
5866 @item --expression=@var{expr}
5867 @itemx -e @var{expr}
5868 Consider the package @var{expr} evaluates to.
5870 This is useful to precisely refer to a package, as in this example:
5873 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
5878 @node Invoking guix environment
5879 @section Invoking @command{guix environment}
5881 @cindex reproducible build environments
5882 @cindex development environments
5883 @cindex @command{guix environment}
5884 @cindex environment, package build environment
5885 The purpose of @command{guix environment} is to assist hackers in
5886 creating reproducible development environments without polluting their
5887 package profile. The @command{guix environment} tool takes one or more
5888 packages, builds all of their inputs, and creates a shell
5889 environment to use them.
5891 The general syntax is:
5894 guix environment @var{options} @var{package}@dots{}
5897 The following example spawns a new shell set up for the development of
5901 guix environment guile
5904 If the needed dependencies are not built yet, @command{guix environment}
5905 automatically builds them. The environment of the new shell is an augmented
5906 version of the environment that @command{guix environment} was run in.
5907 It contains the necessary search paths for building the given package
5908 added to the existing environment variables. To create a ``pure''
5909 environment, in which the original environment variables have been unset,
5910 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
5911 environment variables such as @code{PATH} in their @file{~/.bashrc}
5912 file. As a consequence, when @code{guix environment} launches it, Bash
5913 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
5914 environment variables. It is an error to define such environment
5915 variables in @file{.bashrc}; instead, they should be defined in
5916 @file{.bash_profile}, which is sourced only by log-in shells.
5917 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5918 details on Bash start-up files.}.
5920 @vindex GUIX_ENVIRONMENT
5921 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5922 variable in the shell it spawns; its value is the file name of the
5923 profile of this environment. This allows users to, say, define a
5924 specific prompt for development environments in their @file{.bashrc}
5925 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5928 if [ -n "$GUIX_ENVIRONMENT" ]
5930 export PS1="\u@@\h \w [dev]\$ "
5935 ... or to browse the profile:
5938 $ ls "$GUIX_ENVIRONMENT/bin"
5941 Additionally, more than one package may be specified, in which case the
5942 union of the inputs for the given packages are used. For example, the
5943 command below spawns a shell where all of the dependencies of both Guile
5944 and Emacs are available:
5947 guix environment guile emacs
5950 Sometimes an interactive shell session is not desired. An arbitrary
5951 command may be invoked by placing the @code{--} token to separate the
5952 command from the rest of the arguments:
5955 guix environment guile -- make -j4
5958 In other situations, it is more convenient to specify the list of
5959 packages needed in the environment. For example, the following command
5960 runs @command{python} from an environment containing Python@tie{}2.7 and
5964 guix environment --ad-hoc python2-numpy python-2.7 -- python
5967 Furthermore, one might want the dependencies of a package and also some
5968 additional packages that are not build-time or runtime dependencies, but
5969 are useful when developing nonetheless. Because of this, the
5970 @code{--ad-hoc} flag is positional. Packages appearing before
5971 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5972 added to the environment. Packages appearing after are interpreted as
5973 packages that will be added to the environment directly. For example,
5974 the following command creates a Guix development environment that
5975 additionally includes Git and strace:
5978 guix environment guix --ad-hoc git strace
5981 Sometimes it is desirable to isolate the environment as much as
5982 possible, for maximal purity and reproducibility. In particular, when
5983 using Guix on a host distro that is not GuixSD, it is desirable to
5984 prevent access to @file{/usr/bin} and other system-wide resources from
5985 the development environment. For example, the following command spawns
5986 a Guile REPL in a ``container'' where only the store and the current
5987 working directory are mounted:
5990 guix environment --ad-hoc --container guile -- guile
5994 The @code{--container} option requires Linux-libre 3.19 or newer.
5997 The available options are summarized below.
6000 @item --expression=@var{expr}
6001 @itemx -e @var{expr}
6002 Create an environment for the package or list of packages that
6003 @var{expr} evaluates to.
6005 For example, running:
6008 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
6011 starts a shell with the environment for this specific variant of the
6017 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
6020 starts a shell with all the GuixSD base packages available.
6022 The above commands only the use default output of the given packages.
6023 To select other outputs, two element tuples can be specified:
6026 guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
6029 @item --load=@var{file}
6030 @itemx -l @var{file}
6031 Create an environment for the package or list of packages that the code
6032 within @var{file} evaluates to.
6034 As an example, @var{file} might contain a definition like this
6035 (@pxref{Defining Packages}):
6038 @verbatiminclude environment-gdb.scm
6042 Include all specified packages in the resulting environment, as if an
6043 @i{ad hoc} package were defined with them as inputs. This option is
6044 useful for quickly creating an environment without having to write a
6045 package expression to contain the desired inputs.
6047 For instance, the command:
6050 guix environment --ad-hoc guile guile-sdl -- guile
6053 runs @command{guile} in an environment where Guile and Guile-SDL are
6056 Note that this example implicitly asks for the default output of
6057 @code{guile} and @code{guile-sdl}, but it is possible to ask for a
6058 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
6059 of @code{glib} (@pxref{Packages with Multiple Outputs}).
6061 This option may be composed with the default behavior of @command{guix
6062 environment}. Packages appearing before @code{--ad-hoc} are interpreted
6063 as packages whose dependencies will be added to the environment, the
6064 default behavior. Packages appearing after are interpreted as packages
6065 that will be added to the environment directly.
6068 Unset existing environment variables when building the new environment.
6069 This has the effect of creating an environment in which search paths
6070 only contain package inputs.
6072 @item --search-paths
6073 Display the environment variable definitions that make up the
6076 @item --system=@var{system}
6077 @itemx -s @var{system}
6078 Attempt to build for @var{system}---e.g., @code{i686-linux}.
6083 Run @var{command} within an isolated container. The current working
6084 directory outside the container is mapped inside the container.
6085 Additionally, a dummy home directory is created that matches the current
6086 user's home directory, and @file{/etc/passwd} is configured accordingly.
6087 The spawned process runs as the current user outside the container, but
6088 has root privileges in the context of the container.
6092 For containers, share the network namespace with the host system.
6093 Containers created without this flag only have access to the loopback
6096 @item --expose=@var{source}[=@var{target}]
6097 For containers, expose the file system @var{source} from the host system
6098 as the read-only file system @var{target} within the container. If
6099 @var{target} is not specified, @var{source} is used as the target mount
6100 point in the container.
6102 The example below spawns a Guile REPL in a container in which the user's
6103 home directory is accessible read-only via the @file{/exchange}
6107 guix environment --container --expose=$HOME=/exchange guile -- guile
6110 @item --share=@var{source}[=@var{target}]
6111 For containers, share the file system @var{source} from the host system
6112 as the writable file system @var{target} within the container. If
6113 @var{target} is not specified, @var{source} is used as the target mount
6114 point in the container.
6116 The example below spawns a Guile REPL in a container in which the user's
6117 home directory is accessible for both reading and writing via the
6118 @file{/exchange} directory:
6121 guix environment --container --share=$HOME=/exchange guile -- guile
6125 It also supports all of the common build options that @command{guix
6126 build} supports (@pxref{Common Build Options}).
6128 @node Invoking guix publish
6129 @section Invoking @command{guix publish}
6131 @cindex @command{guix publish}
6132 The purpose of @command{guix publish} is to enable users to easily share
6133 their store with others, who can then use it as a substitute server
6134 (@pxref{Substitutes}).
6136 When @command{guix publish} runs, it spawns an HTTP server which allows
6137 anyone with network access to obtain substitutes from it. This means
6138 that any machine running Guix can also act as if it were a build farm,
6139 since the HTTP interface is compatible with Hydra, the software behind
6140 the @code{hydra.gnu.org} build farm.
6142 For security, each substitute is signed, allowing recipients to check
6143 their authenticity and integrity (@pxref{Substitutes}). Because
6144 @command{guix publish} uses the signing key of the system, which is only
6145 readable by the system administrator, it must be started as root; the
6146 @code{--user} option makes it drop root privileges early on.
6148 The signing key pair must be generated before @command{guix publish} is
6149 launched, using @command{guix archive --generate-key} (@pxref{Invoking
6152 The general syntax is:
6155 guix publish @var{options}@dots{}
6158 Running @command{guix publish} without any additional arguments will
6159 spawn an HTTP server on port 8080:
6165 Once a publishing server has been authorized (@pxref{Invoking guix
6166 archive}), the daemon may download substitutes from it:
6169 guix-daemon --substitute-urls=http://example.org:8080
6172 As a bonus, @command{guix publish} also serves as a content-addressed
6173 mirror for source files referenced in @code{origin} records
6174 (@pxref{origin Reference}). For instance, assuming @command{guix
6175 publish} is running on @code{example.org}, the following URL returns the
6176 raw @file{hello-2.10.tar.gz} file with the given SHA256 hash
6177 (represented in @code{nix-base32} format, @pxref{Invoking guix hash}):
6180 http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i
6183 Obviously, these URLs only work for files that are in the store; in
6184 other cases, they return 404 (``Not Found'').
6186 The following options are available:
6189 @item --port=@var{port}
6190 @itemx -p @var{port}
6191 Listen for HTTP requests on @var{port}.
6193 @item --listen=@var{host}
6194 Listen on the network interface for @var{host}. The default is to
6195 accept connections from any interface.
6197 @item --user=@var{user}
6198 @itemx -u @var{user}
6199 Change privileges to @var{user} as soon as possible---i.e., once the
6200 server socket is open and the signing key has been read.
6202 @item --compression[=@var{level}]
6203 @itemx -C [@var{level}]
6204 Compress data using the given @var{level}. When @var{level} is zero,
6205 disable compression. The range 1 to 9 corresponds to different gzip
6206 compression levels: 1 is the fastest, and 9 is the best (CPU-intensive).
6209 Compression occurs on the fly and the compressed streams are not
6210 cached. Thus, to reduce load on the machine that runs @command{guix
6211 publish}, it may be a good idea to choose a low compression level, or to
6212 run @command{guix publish} behind a caching proxy.
6214 @item --ttl=@var{ttl}
6215 Produce @code{Cache-Control} HTTP headers that advertise a time-to-live
6216 (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5
6217 days, @code{1m} means 1 month, and so on.
6219 This allows the user's Guix to keep substitute information in cache for
6220 @var{ttl}. However, note that @code{guix publish} does not itself
6221 guarantee that the store items it provides will indeed remain available
6222 for as long as @var{ttl}.
6224 @item --repl[=@var{port}]
6225 @itemx -r [@var{port}]
6226 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
6227 Reference Manual}) on @var{port} (37146 by default). This is used
6228 primarily for debugging a running @command{guix publish} server.
6231 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
6232 add a call to @code{guix-publish-service} in the @code{services} field
6233 of the @code{operating-system} declaration (@pxref{guix-publish-service,
6234 @code{guix-publish-service}}).
6236 If you are instead running Guix on a ``foreign distro'', follow these
6241 If your host distro uses the systemd init system:
6244 # ln -s ~root/.guix-profile/lib/systemd/system/guix-publish.service \
6245 /etc/systemd/system/
6246 # systemctl start guix-publish && systemctl enable guix-publish
6250 If your host distro uses the Upstart init system:
6253 # ln -s ~root/.guix-profile/lib/upstart/system/guix-publish.conf /etc/init/
6254 # start guix-publish
6258 Otherwise, proceed similarly with your distro's init system.
6261 @node Invoking guix challenge
6262 @section Invoking @command{guix challenge}
6264 @cindex reproducible builds
6265 @cindex verifiable builds
6266 @cindex @command{guix challenge}
6268 Do the binaries provided by this server really correspond to the source
6269 code it claims to build? Is a package build process deterministic?
6270 These are the questions the @command{guix challenge} command attempts to
6273 The former is obviously an important question: Before using a substitute
6274 server (@pxref{Substitutes}), one had better @emph{verify} that it
6275 provides the right binaries, and thus @emph{challenge} it. The latter
6276 is what enables the former: If package builds are deterministic, then
6277 independent builds of the package should yield the exact same result,
6278 bit for bit; if a server provides a binary different from the one
6279 obtained locally, it may be either corrupt or malicious.
6281 We know that the hash that shows up in @file{/gnu/store} file names is
6282 the hash of all the inputs of the process that built the file or
6283 directory---compilers, libraries, build scripts,
6284 etc. (@pxref{Introduction}). Assuming deterministic build processes,
6285 one store file name should map to exactly one build output.
6286 @command{guix challenge} checks whether there is, indeed, a single
6287 mapping by comparing the build outputs of several independent builds of
6288 any given store item.
6290 The command output looks like this:
6293 $ guix challenge --substitute-urls="https://hydra.gnu.org https://guix.example.org"
6294 updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
6295 updating list of substitutes from 'https://guix.example.org'... 100.0%
6296 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
6297 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
6298 https://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
6299 https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
6300 /gnu/store/@dots{}-git-2.5.0 contents differ:
6301 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
6302 https://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
6303 https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
6304 /gnu/store/@dots{}-pius-2.1.1 contents differ:
6305 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
6306 https://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
6307 https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
6311 In this example, @command{guix challenge} first scans the store to
6312 determine the set of locally-built derivations---as opposed to store
6313 items that were downloaded from a substitute server---and then queries
6314 all the substitute servers. It then reports those store items for which
6315 the servers obtained a result different from the local build.
6317 @cindex non-determinism, in package builds
6318 As an example, @code{guix.example.org} always gets a different answer.
6319 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
6320 case of Git. This might indicate that the build process of Git is
6321 non-deterministic, meaning that its output varies as a function of
6322 various things that Guix does not fully control, in spite of building
6323 packages in isolated environments (@pxref{Features}). Most common
6324 sources of non-determinism include the addition of timestamps in build
6325 results, the inclusion of random numbers, and directory listings sorted
6326 by inode number. See @uref{https://reproducible-builds.org/docs/}, for
6329 To find out what is wrong with this Git binary, we can do something along
6330 these lines (@pxref{Invoking guix archive}):
6333 $ wget -q -O - https://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
6334 | guix archive -x /tmp/git
6335 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
6338 This command shows the difference between the files resulting from the
6339 local build, and the files resulting from the build on
6340 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
6341 diffutils, Comparing and Merging Files}). The @command{diff} command
6342 works great for text files. When binary files differ, a better option
6343 is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps
6344 visualize differences for all kinds of files.
6346 Once you have done that work, you can tell whether the differences are due
6347 to a non-deterministic build process or to a malicious server. We try
6348 hard to remove sources of non-determinism in packages to make it easier
6349 to verify substitutes, but of course, this is a process that
6350 involves not just Guix, but a large part of the free software community.
6351 In the meantime, @command{guix challenge} is one tool to help address
6354 If you are writing packages for Guix, you are encouraged to check
6355 whether @code{hydra.gnu.org} and other substitute servers obtain the
6356 same build result as you did with:
6359 $ guix challenge @var{package}
6363 where @var{package} is a package specification such as
6364 @code{guile@@2.0} or @code{glibc:debug}.
6366 The general syntax is:
6369 guix challenge @var{options} [@var{packages}@dots{}]
6372 When a difference is found between the hash of a locally-built item and
6373 that of a server-provided substitute, or among substitutes provided by
6374 different servers, the command displays it as in the example above and
6375 its exit code is 2 (other non-zero exit codes denote other kinds of
6378 The one option that matters is:
6382 @item --substitute-urls=@var{urls}
6383 Consider @var{urls} the whitespace-separated list of substitute source
6389 @node Invoking guix container
6390 @section Invoking @command{guix container}
6392 @cindex @command{guix container}
6394 As of version @value{VERSION}, this tool is experimental. The interface
6395 is subject to radical change in the future.
6398 The purpose of @command{guix container} is to manipulate processes
6399 running within an isolated environment, commonly known as a
6400 ``container'', typically created by the @command{guix environment}
6401 (@pxref{Invoking guix environment}) and @command{guix system container}
6402 (@pxref{Invoking guix system}) commands.
6404 The general syntax is:
6407 guix container @var{action} @var{options}@dots{}
6410 @var{action} specifies the operation to perform with a container, and
6411 @var{options} specifies the context-specific arguments for the action.
6413 The following actions are available:
6417 Execute a command within the context of a running container.
6422 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
6425 @var{pid} specifies the process ID of the running container.
6426 @var{program} specifies an executable file name within the root file
6427 system of the container. @var{arguments} are the additional options that
6428 will be passed to @var{program}.
6430 The following command launches an interactive login shell inside a
6431 GuixSD container, started by @command{guix system container}, and whose
6435 guix container exec 9001 /run/current-system/profile/bin/bash --login
6438 Note that the @var{pid} cannot be the parent process of a container. It
6439 must be PID 1 of the container or one of its child processes.
6443 @c *********************************************************************
6444 @node GNU Distribution
6445 @chapter GNU Distribution
6447 @cindex Guix System Distribution
6449 Guix comes with a distribution of the GNU system consisting entirely of
6450 free software@footnote{The term ``free'' here refers to the
6451 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
6452 users of that software}.}. The
6453 distribution can be installed on its own (@pxref{System Installation}),
6454 but it is also possible to install Guix as a package manager on top of
6455 an installed GNU/Linux system (@pxref{Installation}). To distinguish
6456 between the two, we refer to the standalone distribution as the Guix
6457 System Distribution, or GuixSD.
6459 The distribution provides core GNU packages such as GNU libc, GCC, and
6460 Binutils, as well as many GNU and non-GNU applications. The complete
6461 list of available packages can be browsed
6462 @url{http://www.gnu.org/software/guix/packages,on-line} or by
6463 running @command{guix package} (@pxref{Invoking guix package}):
6466 guix package --list-available
6469 Our goal is to provide a practical 100% free software distribution of
6470 Linux-based and other variants of GNU, with a focus on the promotion and
6471 tight integration of GNU components, and an emphasis on programs and
6472 tools that help users exert that freedom.
6474 Packages are currently available on the following platforms:
6479 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
6482 Intel 32-bit architecture (IA32), Linux-Libre kernel;
6485 ARMv7-A architecture with hard float, Thumb-2 and NEON,
6486 using the EABI hard-float application binary interface (ABI),
6487 and Linux-Libre kernel.
6489 @item mips64el-linux
6490 little-endian 64-bit MIPS processors, specifically the Loongson series,
6491 n32 ABI, and Linux-Libre kernel.
6495 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
6498 For information on porting to other architectures or kernels,
6502 * System Installation:: Installing the whole operating system.
6503 * System Configuration:: Configuring the operating system.
6504 * Installing Debugging Files:: Feeding the debugger.
6505 * Security Updates:: Deploying security fixes quickly.
6506 * Package Modules:: Packages from the programmer's viewpoint.
6507 * Packaging Guidelines:: Growing the distribution.
6508 * Bootstrapping:: GNU/Linux built from scratch.
6509 * Porting:: Targeting another platform or kernel.
6512 Building this distribution is a cooperative effort, and you are invited
6513 to join! @xref{Contributing}, for information about how you can help.
6515 @node System Installation
6516 @section System Installation
6518 @cindex installing GuixSD
6519 @cindex Guix System Distribution
6520 This section explains how to install the Guix System Distribution (GuixSD)
6521 on a machine. The Guix package manager can
6522 also be installed on top of a running GNU/Linux system,
6523 @pxref{Installation}.
6527 @c This paragraph is for people reading this from tty2 of the
6528 @c installation image.
6529 You are reading this documentation with an Info reader. For details on
6530 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
6531 link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU
6532 Info}. Hit @kbd{l} afterwards to come back here.
6534 Alternately, run @command{info info} in another tty to keep the manual
6540 * Limitations:: What you can expect.
6541 * Hardware Considerations:: Supported hardware.
6542 * USB Stick Installation:: Preparing the installation medium.
6543 * Preparing for Installation:: Networking, partitioning, etc.
6544 * Proceeding with the Installation:: The real thing.
6545 * Installing GuixSD in a VM:: GuixSD playground.
6546 * Building the Installation Image:: How this comes to be.
6550 @subsection Limitations
6552 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
6553 not production-ready. It may contain bugs and lack important
6554 features. Thus, if you are looking for a stable production system that
6555 respects your freedom as a computer user, a good solution at this point
6556 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
6557 the more established GNU/Linux distributions}. We hope you can soon switch
6558 to the GuixSD without fear, of course. In the meantime, you can
6559 also keep using your distribution and try out the package manager on top
6560 of it (@pxref{Installation}).
6562 Before you proceed with the installation, be aware of the following
6563 noteworthy limitations applicable to version @value{VERSION}:
6567 The installation process does not include a graphical user interface and
6568 requires familiarity with GNU/Linux (see the following subsections to
6569 get a feel of what that means.)
6572 Support for the Logical Volume Manager (LVM) is missing.
6575 Few system services are currently supported out-of-the-box
6579 More than 4,000 packages are available, but you may
6580 occasionally find that a useful package is missing.
6583 GNOME, Xfce, and Enlightenment are available (@pxref{Desktop Services}),
6584 as well as a number of X11 window managers. However, some graphical
6585 applications may be missing, as well as KDE.
6588 You have been warned! But more than a disclaimer, this is an invitation
6589 to report issues (and success stories!), and to join us in improving it.
6590 @xref{Contributing}, for more info.
6593 @node Hardware Considerations
6594 @subsection Hardware Considerations
6596 @cindex hardware support on GuixSD
6597 GNU@tie{}GuixSD focuses on respecting the user's computing freedom. It
6598 builds around the kernel Linux-libre, which means that only hardware for
6599 which free software drivers and firmware exist is supported. Nowadays,
6600 a wide range of off-the-shelf hardware is supported on
6601 GNU/Linux-libre---from keyboards to graphics cards to scanners and
6602 Ethernet controllers. Unfortunately, there are still areas where
6603 hardware vendors deny users control over their own computing, and such
6604 hardware is not supported on GuixSD.
6606 @cindex WiFi, hardware support
6607 One of the main areas where free drivers or firmware are lacking is WiFi
6608 devices. WiFi devices known to work include those using Atheros chips
6609 (AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre
6610 driver, and those using Broadcom/AirForce chips (BCM43xx with
6611 Wireless-Core Revision 5), which corresponds to the @code{b43-open}
6612 Linux-libre driver. Free firmware exists for both and is available
6613 out-of-the-box on GuixSD, as part of @var{%base-firmware}
6614 (@pxref{operating-system Reference, @code{firmware}}).
6616 @cindex RYF, Respects Your Freedom
6617 The @uref{https://www.fsf.org/, Free Software Foundation} runs
6618 @uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a
6619 certification program for hardware products that respect your freedom
6620 and your privacy and ensure that you have control over your device. We
6621 encourage you to check the list of RYF-certified devices.
6623 Another useful resource is the @uref{https://www.h-node.org/, H-Node}
6624 web site. It contains a catalog of hardware devices with information
6625 about their support in GNU/Linux.
6628 @node USB Stick Installation
6629 @subsection USB Stick Installation
6631 An installation image for USB sticks can be downloaded from
6632 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
6633 where @var{system} is one of:
6637 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
6640 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
6643 @c start duplication of authentication part from ``Binary Installation''
6644 Make sure to download the associated @file{.sig} file and to verify the
6645 authenticity of the image against it, along these lines:
6648 $ wget ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6649 $ gpg --verify guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6652 If that command fails because you do not have the required public key,
6653 then run this command to import it:
6656 $ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
6660 and rerun the @code{gpg --verify} command.
6663 This image contains a single partition with the tools necessary for an
6664 installation. It is meant to be copied @emph{as is} to a large-enough
6667 To copy the image to a USB stick, follow these steps:
6671 Decompress the image using the @command{xz} command:
6674 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
6678 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
6679 its device name. Assuming that the USB stick is known as @file{/dev/sdX},
6680 copy the image with:
6683 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
6686 Access to @file{/dev/sdX} usually requires root privileges.
6689 Once this is done, you should be able to reboot the system and boot from
6690 the USB stick. The latter usually requires you to get in the BIOS' boot
6691 menu, where you can choose to boot from the USB stick.
6693 @xref{Installing GuixSD in a VM}, if, instead, you would like to install
6694 GuixSD in a virtual machine (VM).
6696 @node Preparing for Installation
6697 @subsection Preparing for Installation
6699 Once you have successfully booted the image on the USB stick, you should
6700 end up with a root prompt. Several console TTYs are configured and can
6701 be used to run commands as root. TTY2 shows this documentation,
6702 browsable using the Info reader commands (@pxref{Top,,, info-stnd,
6703 Stand-alone GNU Info}). The installation system runs the GPM mouse
6704 daemon, which allows you to select text with the left mouse button and
6705 to paste it with the middle button.
6708 Installation requires access to the Internet so that any missing
6709 dependencies of your system configuration can be downloaded. See the
6710 ``Networking'' section below.
6713 The installation system includes many common tools needed for this task.
6714 But it is also a full-blown GuixSD system, which means that you can
6715 install additional packages, should you need it, using @command{guix
6716 package} (@pxref{Invoking guix package}).
6718 @subsubsection Keyboard Layout
6720 @cindex keyboard layout
6721 The installation image uses the US qwerty keyboard layout. If you want
6722 to change it, you can use the @command{loadkeys} command. For example,
6723 the following command selects the Dvorak keyboard layout:
6729 See the files under @file{/run/current-system/profile/share/keymaps} for
6730 a list of available keyboard layouts. Run @command{man loadkeys} for
6733 @subsubsection Networking
6735 Run the following command see what your network interfaces are called:
6742 @dots{} or, using the GNU/Linux-specific @command{ip} command:
6748 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
6749 Wired interfaces have a name starting with @samp{e}; for example, the
6750 interface corresponding to the first on-board Ethernet controller is
6751 called @samp{eno1}. Wireless interfaces have a name starting with
6752 @samp{w}, like @samp{w1p2s0}.
6755 @item Wired connection
6756 To configure a wired network run the following command, substituting
6757 @var{interface} with the name of the wired interface you want to use.
6760 ifconfig @var{interface} up
6763 @item Wireless connection
6766 To configure wireless networking, you can create a configuration file
6767 for the @command{wpa_supplicant} configuration tool (its location is not
6768 important) using one of the available text editors such as
6772 zile wpa_supplicant.conf
6775 As an example, the following stanza can go to this file and will work
6776 for many wireless networks, provided you give the actual SSID and
6777 passphrase for the network you are connecting to:
6781 ssid="@var{my-ssid}"
6783 psk="the network's secret passphrase"
6787 Start the wireless service and run it in the background with the
6788 following command (substitute @var{interface} with the name of the
6789 network interface you want to use):
6792 wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
6795 Run @command{man wpa_supplicant} for more information.
6799 At this point, you need to acquire an IP address. On a network where IP
6800 addresses are automatically assigned @i{via} DHCP, you can run:
6803 dhclient -v @var{interface}
6806 Try to ping a server to see if networking is up and running:
6812 Setting up network access is almost always a requirement because the
6813 image does not contain all the software and tools that may be needed.
6815 @subsubsection Disk Partitioning
6817 Unless this has already been done, the next step is to partition, and
6818 then format the target partition(s).
6820 The installation image includes several partitioning tools, including
6821 Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
6822 @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with
6823 the partition layout you want:
6829 Once you are done partitioning the target hard disk drive, you have to
6830 create a file system on the relevant partition(s)@footnote{Currently
6831 GuixSD pretty much assumes an ext4 file system. In particular, code
6832 that reads partition UUIDs and labels only works with ext4. This will
6833 be fixed in the future.}.
6835 Preferably, assign partitions a label so that you can easily and
6836 reliably refer to them in @code{file-system} declarations (@pxref{File
6837 Systems}). This is typically done using the @code{-L} option of
6838 @command{mkfs.ext4} and related commands. So, assuming the target root
6839 partition lives at @file{/dev/sda1}, a file system with the label
6840 @code{my-root} can be created with:
6843 mkfs.ext4 -L my-root /dev/sda1
6846 @cindex encrypted disk
6847 If you are instead planning to encrypt the root partition, you can use
6848 the Cryptsetup/LUKS utilities to do that (see @inlinefmtifelse{html,
6849 @uref{https://linux.die.net/man/8/cryptsetup, @code{man cryptsetup}},
6850 @code{man cryptsetup}} for more information.) Assuming you want to
6851 store the root partition on @file{/dev/sda1}, the command sequence would
6852 be along these lines:
6855 cryptsetup luksFormat /dev/sda1
6856 cryptsetup open --type luks /dev/sda1 my-partition
6857 mkfs.ext4 -L my-root /dev/mapper/my-partition
6860 Once that is done, mount the target root partition under @file{/mnt}
6861 with a command like (again, assuming @code{my-root} is the label of the
6865 mount LABEL=my-root /mnt
6868 Finally, if you plan to use one or more swap partitions (@pxref{Memory
6869 Concepts, swap space,, libc, The GNU C Library Reference Manual}), make
6870 sure to initialize them with @command{mkswap}. Assuming you have one
6871 swap partition on @file{/dev/sda2}, you would run:
6878 @node Proceeding with the Installation
6879 @subsection Proceeding with the Installation
6881 With the target partitions ready and the target root mounted on
6882 @file{/mnt}, we're ready to go. First, run:
6885 herd start cow-store /mnt
6888 This makes @file{/gnu/store} copy-on-write, such that packages added to it
6889 during the installation phase are written to the target disk on @file{/mnt}
6890 rather than kept in memory. This is necessary because the first phase of
6891 the @command{guix system init} command (see below) entails downloads or
6892 builds to @file{/gnu/store} which, initially, is an in-memory file system.
6894 Next, you have to edit a file and
6895 provide the declaration of the operating system to be installed. To
6896 that end, the installation system comes with three text editors: GNU nano
6897 (@pxref{Top,,, nano, GNU nano Manual}), GNU Zile (an Emacs clone), and
6898 nvi (a clone of the original BSD @command{vi} editor).
6899 We strongly recommend storing that file on the target root file system, say,
6900 as @file{/mnt/etc/config.scm}. Failing to do that, you will have lost your
6901 configuration file once you have rebooted into the newly-installed system.
6903 @xref{Using the Configuration System}, for an overview of the
6904 configuration file. The example configurations discussed in that
6905 section are available under @file{/etc/configuration} in the
6906 installation image. Thus, to get started with a system configuration
6907 providing a graphical display server (a ``desktop'' system), you can run
6908 something along these lines:
6912 # cp /etc/configuration/desktop.scm /mnt/etc/config.scm
6913 # zile /mnt/etc/config.scm
6916 You should pay attention to what your configuration file contains, and
6921 Make sure the @code{grub-configuration} form refers to the device you
6922 want to install GRUB on.
6925 Be sure that your partition labels match the value of their respective
6926 @code{device} fields in your @code{file-system} configuration, assuming
6927 your @code{file-system} configuration sets the value of @code{title} to
6931 If there are encrypted or RAID partitions, make sure to add a
6932 @code{mapped-devices} field to describe them (@pxref{Mapped Devices}).
6935 Once you are done preparing the configuration file, the new system must
6936 be initialized (remember that the target root file system is mounted
6940 guix system init /mnt/etc/config.scm /mnt
6944 This copies all the necessary files and installs GRUB on
6945 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
6946 more information, @pxref{Invoking guix system}. This command may trigger
6947 downloads or builds of missing packages, which can take some time.
6949 Once that command has completed---and hopefully succeeded!---you can run
6950 @command{reboot} and boot into the new system. The @code{root} password
6951 in the new system is initially empty; other users' passwords need to be
6952 initialized by running the @command{passwd} command as @code{root},
6953 unless your configuration specifies otherwise
6954 (@pxref{user-account-password, user account passwords}).
6956 @cindex upgrading GuixSD
6957 From then on, you can update GuixSD whenever you want by running
6958 @command{guix pull} as @code{root} (@pxref{Invoking guix pull}), and
6959 then running @command{guix system reconfigure} to build a new system
6960 generation with the latest packages and services (@pxref{Invoking guix
6961 system}). We recommend doing that regularly so that your system
6962 includes the latest security updates (@pxref{Security Updates}).
6964 Join us on @code{#guix} on the Freenode IRC network or on
6965 @file{guix-devel@@gnu.org} to share your experience---good or not so
6968 @node Installing GuixSD in a VM
6969 @subsection Installing GuixSD in a Virtual Machine
6971 @cindex virtual machine, GuixSD installation
6972 If you'd like to install GuixSD in a virtual machine (VM) rather than on
6973 your beloved machine, this section is for you.
6975 To boot a @uref{http://qemu.org/,QEMU} VM for installing GuixSD in a
6976 disk image, follow these steps:
6980 First, retrieve the GuixSD installation image as described previously
6981 (@pxref{USB Stick Installation}).
6984 Create a disk image that will hold the installed system. To make a
6985 qcow2-formatted disk image, use the @command{qemu-img} command:
6988 qemu-img create -f qcow2 guixsd.img 5G
6991 This will create a 5GB file.
6994 Boot the USB installation image in an VM:
6997 qemu-system-x86_64 -m 1024 -smp 1 \
6998 -net default -net nic,model=virtio -boot menu=on \
6999 -drive file=guixsd.img \
7000 -drive file=guixsd-usb-install-@value{VERSION}.@var{system}
7003 In the VM console, quickly press the @kbd{F12} key to enter the boot
7004 menu. Then press the @kbd{2} key and the @kbd{RET} key to validate your
7008 You're now root in the VM, proceed with the installation process.
7009 @xref{Preparing for Installation}, and follow the instructions.
7012 Once installation is complete, you can boot the system that's on your
7013 @file{guixsd.img} image. @xref{Running GuixSD in a VM}, for how to do
7016 @node Building the Installation Image
7017 @subsection Building the Installation Image
7019 @cindex installation image
7020 The installation image described above was built using the @command{guix
7021 system} command, specifically:
7023 @c FIXME: 1G is too much; see <http://bugs.gnu.org/23077>.
7025 guix system disk-image --image-size=1G gnu/system/install.scm
7028 Have a look at @file{gnu/system/install.scm} in the source tree,
7029 and see also @ref{Invoking guix system} for more information
7030 about the installation image.
7032 @node System Configuration
7033 @section System Configuration
7035 @cindex system configuration
7036 The Guix System Distribution supports a consistent whole-system configuration
7037 mechanism. By that we mean that all aspects of the global system
7038 configuration---such as the available system services, timezone and
7039 locale settings, user accounts---are declared in a single place. Such
7040 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
7042 One of the advantages of putting all the system configuration under the
7043 control of Guix is that it supports transactional system upgrades, and
7044 makes it possible to roll back to a previous system instantiation,
7045 should something go wrong with the new one (@pxref{Features}). Another
7046 advantage is that it makes it easy to replicate the exact same configuration
7047 across different machines, or at different points in time, without
7048 having to resort to additional administration tools layered on top of
7049 the own tools of the system.
7050 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
7052 This section describes this mechanism. First we focus on the system
7053 administrator's viewpoint---explaining how the system is configured and
7054 instantiated. Then we show how this mechanism can be extended, for
7055 instance to support new system services.
7058 * Using the Configuration System:: Customizing your GNU system.
7059 * operating-system Reference:: Detail of operating-system declarations.
7060 * File Systems:: Configuring file system mounts.
7061 * Mapped Devices:: Block device extra processing.
7062 * User Accounts:: Specifying user accounts.
7063 * Locales:: Language and cultural convention settings.
7064 * Services:: Specifying system services.
7065 * Setuid Programs:: Programs running with root privileges.
7066 * X.509 Certificates:: Authenticating HTTPS servers.
7067 * Name Service Switch:: Configuring libc's name service switch.
7068 * Initial RAM Disk:: Linux-Libre bootstrapping.
7069 * GRUB Configuration:: Configuring the boot loader.
7070 * Invoking guix system:: Instantiating a system configuration.
7071 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
7072 * Defining Services:: Adding new service definitions.
7075 @node Using the Configuration System
7076 @subsection Using the Configuration System
7078 The operating system is configured by providing an
7079 @code{operating-system} declaration in a file that can then be passed to
7080 the @command{guix system} command (@pxref{Invoking guix system}). A
7081 simple setup, with the default system services, the default Linux-Libre
7082 kernel, initial RAM disk, and boot loader looks like this:
7084 @findex operating-system
7086 @include os-config-bare-bones.texi
7089 This example should be self-describing. Some of the fields defined
7090 above, such as @code{host-name} and @code{bootloader}, are mandatory.
7091 Others, such as @code{packages} and @code{services}, can be omitted, in
7092 which case they get a default value.
7094 Below we discuss the effect of some of the most important fields
7095 (@pxref{operating-system Reference}, for details about all the available
7096 fields), and how to @dfn{instantiate} the operating system using
7097 @command{guix system}.
7099 @unnumberedsubsubsec Globally-Visible Packages
7101 @vindex %base-packages
7102 The @code{packages} field lists packages that will be globally visible
7103 on the system, for all user accounts---i.e., in every user's @code{PATH}
7104 environment variable---in addition to the per-user profiles
7105 (@pxref{Invoking guix package}). The @var{%base-packages} variable
7106 provides all the tools one would expect for basic user and administrator
7107 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
7108 the GNU Zile lightweight text editor, @command{find}, @command{grep},
7109 etc. The example above adds tcpdump to those, taken from the @code{(gnu
7110 packages admin)} module (@pxref{Package Modules}).
7112 @findex specification->package
7113 Referring to packages by variable name, like @var{tcpdump} above, has
7114 the advantage of being unambiguous; it also allows typos and such to be
7115 diagnosed right away as ``unbound variables''. The downside is that one
7116 needs to know which module defines which package, and to augment the
7117 @code{use-package-modules} line accordingly. To avoid that, one can use
7118 the @code{specification->package} procedure of the @code{(gnu packages)}
7119 module, which returns the best package for a given name or name and
7123 (use-modules (gnu packages))
7127 (packages (append (map specification->package
7128 '("tcpdump" "htop" "gnupg@@2.0"))
7132 @unnumberedsubsubsec System Services
7135 @vindex %base-services
7136 The @code{services} field lists @dfn{system services} to be made
7137 available when the system starts (@pxref{Services}).
7138 The @code{operating-system} declaration above specifies that, in
7139 addition to the basic services, we want the @command{lshd} secure shell
7140 daemon listening on port 2222 (@pxref{Networking Services,
7141 @code{lsh-service}}). Under the hood,
7142 @code{lsh-service} arranges so that @code{lshd} is started with the
7143 right command-line options, possibly with supporting configuration files
7144 generated as needed (@pxref{Defining Services}).
7146 @cindex customization, of services
7147 @findex modify-services
7148 Occasionally, instead of using the base services as is, you will want to
7149 customize them. To do this, use @code{modify-services} (@pxref{Service
7150 Reference, @code{modify-services}}) to modify the list.
7152 For example, suppose you want to modify @code{guix-daemon} and Mingetty
7153 (the console log-in) in the @var{%base-services} list (@pxref{Base
7154 Services, @code{%base-services}}). To do that, you can write the
7155 following in your operating system declaration:
7158 (define %my-services
7159 ;; My very own list of services.
7160 (modify-services %base-services
7161 (guix-service-type config =>
7164 (use-substitutes? #f)
7165 (extra-options '("--gc-keep-derivations"))))
7166 (mingetty-service-type config =>
7167 (mingetty-configuration
7168 (inherit config)))))
7172 (services %my-services))
7175 This changes the configuration---i.e., the service parameters---of the
7176 @code{guix-service-type} instance, and that of all the
7177 @code{mingetty-service-type} instances in the @var{%base-services} list.
7178 Observe how this is accomplished: first, we arrange for the original
7179 configuration to be bound to the identifier @code{config} in the
7180 @var{body}, and then we write the @var{body} so that it evaluates to the
7181 desired configuration. In particular, notice how we use @code{inherit}
7182 to create a new configuration which has the same values as the old
7183 configuration, but with a few modifications.
7185 @cindex encrypted disk
7186 The configuration for a typical ``desktop'' usage, with an encrypted
7187 root partition, the X11 display
7188 server, GNOME and Xfce (users can choose which of these desktop
7189 environments to use at the log-in screen by pressing @kbd{F1}), network
7190 management, power management, and more, would look like this:
7193 @include os-config-desktop.texi
7196 A graphical environment with a choice of lightweight window managers
7197 instead of full-blown desktop environments would look like this:
7200 @include os-config-lightweight-desktop.texi
7203 @xref{Desktop Services}, for the exact list of services provided by
7204 @var{%desktop-services}. @xref{X.509 Certificates}, for background
7205 information about the @code{nss-certs} package that is used here.
7207 Again, @var{%desktop-services} is just a list of service objects. If
7208 you want to remove services from there, you can do so using the
7209 procedures for list filtering (@pxref{SRFI-1 Filtering and
7210 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
7211 following expression returns a list that contains all the services in
7212 @var{%desktop-services} minus the Avahi service:
7215 (remove (lambda (service)
7216 (eq? (service-kind service) avahi-service-type))
7220 @unnumberedsubsubsec Instantiating the System
7222 Assuming the @code{operating-system} declaration
7223 is stored in the @file{my-system-config.scm}
7224 file, the @command{guix system reconfigure my-system-config.scm} command
7225 instantiates that configuration, and makes it the default GRUB boot
7226 entry (@pxref{Invoking guix system}).
7228 The normal way to change the system configuration is by updating this
7229 file and re-running @command{guix system reconfigure}. One should never
7230 have to touch files in @file{/etc} or to run commands that modify the
7231 system state such as @command{useradd} or @command{grub-install}. In
7232 fact, you must avoid that since that would not only void your warranty
7233 but also prevent you from rolling back to previous versions of your
7234 system, should you ever need to.
7236 @cindex roll-back, of the operating system
7237 Speaking of roll-back, each time you run @command{guix system
7238 reconfigure}, a new @dfn{generation} of the system is created---without
7239 modifying or deleting previous generations. Old system generations get
7240 an entry in the GRUB boot menu, allowing you to boot them in case
7241 something went wrong with the latest generation. Reassuring, no? The
7242 @command{guix system list-generations} command lists the system
7243 generations available on disk. It is also possible to roll back the
7244 system via the commands @command{guix system roll-back} and
7245 @command{guix system switch-generation}.
7247 Although the command @command{guix system reconfigure} will not modify
7248 previous generations, must take care when the current generation is not
7249 the latest (e.g., after invoking @command{guix system roll-back}), since
7250 the operation might overwrite a later generation (@pxref{Invoking guix
7253 @unnumberedsubsubsec The Programming Interface
7255 At the Scheme level, the bulk of an @code{operating-system} declaration
7256 is instantiated with the following monadic procedure (@pxref{The Store
7259 @deffn {Monadic Procedure} operating-system-derivation os
7260 Return a derivation that builds @var{os}, an @code{operating-system}
7261 object (@pxref{Derivations}).
7263 The output of the derivation is a single directory that refers to all
7264 the packages, configuration files, and other supporting files needed to
7265 instantiate @var{os}.
7268 This procedure is provided by the @code{(gnu system)} module. Along
7269 with @code{(gnu services)} (@pxref{Services}), this module contains the
7270 guts of GuixSD. Make sure to visit it!
7273 @node operating-system Reference
7274 @subsection @code{operating-system} Reference
7276 This section summarizes all the options available in
7277 @code{operating-system} declarations (@pxref{Using the Configuration
7280 @deftp {Data Type} operating-system
7281 This is the data type representing an operating system configuration.
7282 By that, we mean all the global system configuration, not per-user
7283 configuration (@pxref{Using the Configuration System}).
7286 @item @code{kernel} (default: @var{linux-libre})
7287 The package object of the operating system kernel to use@footnote{Currently
7288 only the Linux-libre kernel is supported. In the future, it will be
7289 possible to use the GNU@tie{}Hurd.}.
7291 @item @code{kernel-arguments} (default: @code{'()})
7292 List of strings or gexps representing additional arguments to pass on
7293 the command-line of the kernel---e.g., @code{("console=ttyS0")}.
7295 @item @code{bootloader}
7296 The system bootloader configuration object. @xref{GRUB Configuration}.
7298 @item @code{initrd} (default: @code{base-initrd})
7300 @cindex initial RAM disk
7301 A two-argument monadic procedure that returns an initial RAM disk for
7302 the Linux kernel. @xref{Initial RAM Disk}.
7304 @item @code{firmware} (default: @var{%base-firmware})
7306 List of firmware packages loadable by the operating system kernel.
7308 The default includes firmware needed for Atheros- and Broadcom-based
7309 WiFi devices (Linux-libre modules @code{ath9k} and @code{b43-open},
7310 respectively). @xref{Hardware Considerations}, for more info on
7313 @item @code{host-name}
7316 @item @code{hosts-file}
7318 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
7319 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
7320 Reference Manual}). The default is a file with entries for
7321 @code{localhost} and @var{host-name}.
7323 @item @code{mapped-devices} (default: @code{'()})
7324 A list of mapped devices. @xref{Mapped Devices}.
7326 @item @code{file-systems}
7327 A list of file systems. @xref{File Systems}.
7329 @item @code{swap-devices} (default: @code{'()})
7330 @cindex swap devices
7331 A list of strings identifying devices to be used for ``swap space''
7332 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
7333 For example, @code{'("/dev/sda3")}.
7335 @item @code{users} (default: @code{%base-user-accounts})
7336 @itemx @code{groups} (default: @var{%base-groups})
7337 List of user accounts and groups. @xref{User Accounts}.
7339 @item @code{skeletons} (default: @code{(default-skeletons)})
7340 A list target file name/file-like object tuples (@pxref{G-Expressions,
7341 file-like objects}). These are the skeleton files that will be added to
7342 the home directory of newly-created user accounts.
7344 For instance, a valid value may look like this:
7347 `((".bashrc" ,(plain-file "bashrc" "echo Hello\n"))
7348 (".guile" ,(plain-file "guile"
7349 "(use-modules (ice-9 readline))
7350 (activate-readline)")))
7353 @item @code{issue} (default: @var{%default-issue})
7354 A string denoting the contents of the @file{/etc/issue} file, which is
7355 displayed when users log in on a text console.
7357 @item @code{packages} (default: @var{%base-packages})
7358 The set of packages installed in the global profile, which is accessible
7359 at @file{/run/current-system/profile}.
7361 The default set includes core utilities and it is good practice to
7362 install non-core utilities in user profiles (@pxref{Invoking guix
7365 @item @code{timezone}
7366 A timezone identifying string---e.g., @code{"Europe/Paris"}.
7368 You can run the @command{tzselect} command to find out which timezone
7369 string corresponds to your region. Choosing an invalid timezone name
7370 causes @command{guix system} to fail.
7372 @item @code{locale} (default: @code{"en_US.utf8"})
7373 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
7374 Library Reference Manual}). @xref{Locales}, for more information.
7376 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
7377 The list of locale definitions to be compiled and that may be used at
7378 run time. @xref{Locales}.
7380 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
7381 The list of GNU@tie{}libc packages whose locale data and tools are used
7382 to build the locale definitions. @xref{Locales}, for compatibility
7383 considerations that justify this option.
7385 @item @code{name-service-switch} (default: @var{%default-nss})
7386 Configuration of the libc name service switch (NSS)---a
7387 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
7390 @item @code{services} (default: @var{%base-services})
7391 A list of service objects denoting system services. @xref{Services}.
7393 @item @code{pam-services} (default: @code{(base-pam-services)})
7395 @cindex pluggable authentication modules
7396 Linux @dfn{pluggable authentication module} (PAM) services.
7397 @c FIXME: Add xref to PAM services section.
7399 @item @code{setuid-programs} (default: @var{%setuid-programs})
7400 List of string-valued G-expressions denoting setuid programs.
7401 @xref{Setuid Programs}.
7403 @item @code{sudoers-file} (default: @var{%sudoers-specification})
7404 @cindex sudoers file
7405 The contents of the @file{/etc/sudoers} file as a file-like object
7406 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
7408 This file specifies which users can use the @command{sudo} command, what
7409 they are allowed to do, and what privileges they may gain. The default
7410 is that only @code{root} and members of the @code{wheel} group may use
7417 @subsection File Systems
7419 The list of file systems to be mounted is specified in the
7420 @code{file-systems} field of the operating system declaration
7421 (@pxref{Using the Configuration System}). Each file system is declared
7422 using the @code{file-system} form, like this:
7426 (mount-point "/home")
7427 (device "/dev/sda3")
7431 As usual, some of the fields are mandatory---those shown in the example
7432 above---while others can be omitted. These are described below.
7434 @deftp {Data Type} file-system
7435 Objects of this type represent file systems to be mounted. They
7436 contain the following members:
7440 This is a string specifying the type of the file system---e.g.,
7443 @item @code{mount-point}
7444 This designates the place where the file system is to be mounted.
7447 This names the ``source'' of the file system. By default it is the name
7448 of a node under @file{/dev}, but its meaning depends on the @code{title}
7449 field described below.
7451 @item @code{title} (default: @code{'device})
7452 This is a symbol that specifies how the @code{device} field is to be
7455 When it is the symbol @code{device}, then the @code{device} field is
7456 interpreted as a file name; when it is @code{label}, then @code{device}
7457 is interpreted as a partition label name; when it is @code{uuid},
7458 @code{device} is interpreted as a partition unique identifier (UUID).
7460 UUIDs may be converted from their string representation (as shown by the
7461 @command{tune2fs -l} command) using the @code{uuid} form@footnote{The
7462 @code{uuid} form expects 16-byte UUIDs as defined in
7463 @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
7464 form of UUID used by the ext2 family of file systems and others, but it
7465 is different from ``UUIDs'' found in FAT file systems, for instance.},
7470 (mount-point "/home")
7473 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
7476 The @code{label} and @code{uuid} options offer a way to refer to disk
7477 partitions without having to hard-code their actual device
7478 name@footnote{Note that, while it is tempting to use
7479 @file{/dev/disk/by-uuid} and similar device names to achieve the same
7480 result, this is not recommended: These special device nodes are created
7481 by the udev daemon and may be unavailable at the time the device is
7484 However, when the source of a file system is a mapped device (@pxref{Mapped
7485 Devices}), its @code{device} field @emph{must} refer to the mapped
7486 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
7487 @code{title} must be set to @code{'device}. This is required so that
7488 the system knows that mounting the file system depends on having the
7489 corresponding device mapping established.
7491 @item @code{flags} (default: @code{'()})
7492 This is a list of symbols denoting mount flags. Recognized flags
7493 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
7494 access to special files), @code{no-suid} (ignore setuid and setgid
7495 bits), and @code{no-exec} (disallow program execution.)
7497 @item @code{options} (default: @code{#f})
7498 This is either @code{#f}, or a string denoting mount options.
7500 @item @code{mount?} (default: @code{#t})
7501 This value indicates whether to automatically mount the file system when
7502 the system is brought up. When set to @code{#f}, the file system gets
7503 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
7504 is not automatically mounted.
7506 @item @code{needed-for-boot?} (default: @code{#f})
7507 This Boolean value indicates whether the file system is needed when
7508 booting. If that is true, then the file system is mounted when the
7509 initial RAM disk (initrd) is loaded. This is always the case, for
7510 instance, for the root file system.
7512 @item @code{check?} (default: @code{#t})
7513 This Boolean indicates whether the file system needs to be checked for
7514 errors before being mounted.
7516 @item @code{create-mount-point?} (default: @code{#f})
7517 When true, the mount point is created if it does not exist yet.
7519 @item @code{dependencies} (default: @code{'()})
7520 This is a list of @code{<file-system>} or @code{<mapped-device>} objects
7521 representing file systems that must be mounted or mapped devices that
7522 must be opened before (and unmounted or closed after) this one.
7524 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
7525 a dependency of @file{/sys/fs/cgroup/cpu} and
7526 @file{/sys/fs/cgroup/memory}.
7528 Another example is a file system that depends on a mapped device, for
7529 example for an encrypted partition (@pxref{Mapped Devices}).
7533 The @code{(gnu system file-systems)} exports the following useful
7536 @defvr {Scheme Variable} %base-file-systems
7537 These are essential file systems that are required on normal systems,
7538 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
7539 below.) Operating system declarations should always contain at least
7543 @defvr {Scheme Variable} %pseudo-terminal-file-system
7544 This is the file system to be mounted as @file{/dev/pts}. It supports
7545 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
7546 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
7547 Manual}). Pseudo-terminals are used by terminal emulators such as
7551 @defvr {Scheme Variable} %shared-memory-file-system
7552 This file system is mounted as @file{/dev/shm} and is used to support
7553 memory sharing across processes (@pxref{Memory-mapped I/O,
7554 @code{shm_open},, libc, The GNU C Library Reference Manual}).
7557 @defvr {Scheme Variable} %immutable-store
7558 This file system performs a read-only ``bind mount'' of
7559 @file{/gnu/store}, making it read-only for all the users including
7560 @code{root}. This prevents against accidental modification by software
7561 running as @code{root} or by system administrators.
7563 The daemon itself is still able to write to the store: it remounts it
7564 read-write in its own ``name space.''
7567 @defvr {Scheme Variable} %binary-format-file-system
7568 The @code{binfmt_misc} file system, which allows handling of arbitrary
7569 executable file types to be delegated to user space. This requires the
7570 @code{binfmt.ko} kernel module to be loaded.
7573 @defvr {Scheme Variable} %fuse-control-file-system
7574 The @code{fusectl} file system, which allows unprivileged users to mount
7575 and unmount user-space FUSE file systems. This requires the
7576 @code{fuse.ko} kernel module to be loaded.
7579 @node Mapped Devices
7580 @subsection Mapped Devices
7582 @cindex device mapping
7583 @cindex mapped devices
7584 The Linux kernel has a notion of @dfn{device mapping}: a block device,
7585 such as a hard disk partition, can be @dfn{mapped} into another device,
7586 usually in @code{/dev/mapper/},
7587 with additional processing over the data that flows through
7588 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
7589 concept of a ``mapped device'' and that of a file system: both boil down
7590 to @emph{translating} input/output operations made on a file to
7591 operations on its backing store. Thus, the Hurd implements mapped
7592 devices, like file systems, using the generic @dfn{translator} mechanism
7593 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
7594 typical example is encryption device mapping: all writes to the mapped
7595 device are encrypted, and all reads are deciphered, transparently.
7596 Guix extends this notion by considering any device or set of devices that
7597 are @dfn{transformed} in some way to create a new device; for instance,
7598 RAID devices are obtained by @dfn{assembling} several other devices, such
7599 as hard disks or partitions, into a new one that behaves as one partition.
7600 Other examples, not yet implemented, are LVM logical volumes.
7602 Mapped devices are declared using the @code{mapped-device} form,
7603 defined as follows; for examples, see below.
7605 @deftp {Data Type} mapped-device
7606 Objects of this type represent device mappings that will be made when
7607 the system boots up.
7611 This is either a string specifying the name of the block device to be mapped,
7612 such as @code{"/dev/sda3"}, or a list of such strings when several devices
7613 need to be assembled for creating a new one.
7616 This string specifies the name of the resulting mapped device. For
7617 kernel mappers such as encrypted devices of type @code{luks-device-mapping},
7618 specifying @code{"my-partition"} leads to the creation of
7619 the @code{"/dev/mapper/my-partition"} device.
7620 For RAID devices of type @code{raid-device-mapping}, the full device name
7621 such as @code{"/dev/md0"} needs to be given.
7624 This must be a @code{mapped-device-kind} object, which specifies how
7625 @var{source} is mapped to @var{target}.
7629 @defvr {Scheme Variable} luks-device-mapping
7630 This defines LUKS block device encryption using the @command{cryptsetup}
7631 command from the package with the same name. It relies on the
7632 @code{dm-crypt} Linux kernel module.
7635 @defvr {Scheme Variable} raid-device-mapping
7636 This defines a RAID device, which is assembled using the @code{mdadm}
7637 command from the package with the same name. It requires a Linux kernel
7638 module for the appropriate RAID level to be loaded, such as @code{raid456}
7639 for RAID-4, RAID-5 or RAID-6, or @code{raid10} for RAID-10.
7642 @cindex disk encryption
7644 The following example specifies a mapping from @file{/dev/sda3} to
7645 @file{/dev/mapper/home} using LUKS---the
7646 @url{https://gitlab.com/cryptsetup/cryptsetup,Linux Unified Key Setup}, a
7647 standard mechanism for disk encryption.
7648 The @file{/dev/mapper/home}
7649 device can then be used as the @code{device} of a @code{file-system}
7650 declaration (@pxref{File Systems}).
7654 (source "/dev/sda3")
7656 (type luks-device-mapping))
7659 Alternatively, to become independent of device numbering, one may obtain
7660 the LUKS UUID (@dfn{unique identifier}) of the source device by a
7664 cryptsetup luksUUID /dev/sda3
7667 and use it as follows:
7671 (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
7673 (type luks-device-mapping))
7676 A RAID device formed of the partitions @file{/dev/sda1} and @file{/dev/sdb1}
7677 may be declared as follows:
7681 (source (list "/dev/sda1" "/dev/sdb1"))
7683 (type raid-device-mapping))
7686 The @file{/dev/md0} device can then be used as the @code{device} of a
7687 @code{file-system} declaration (@pxref{File Systems}).
7688 Note that the RAID level need not be given; it is chosen during the
7689 initial creation and formatting of the RAID device and is determined
7690 automatically later.
7694 @subsection User Accounts
7698 @cindex user accounts
7699 User accounts and groups are entirely managed through the
7700 @code{operating-system} declaration. They are specified with the
7701 @code{user-account} and @code{user-group} forms:
7707 (supplementary-groups '("wheel" ;allow use of sudo, etc.
7709 "video" ;video devices such as webcams
7710 "cdrom")) ;the good ol' CD-ROM
7711 (comment "Bob's sister")
7712 (home-directory "/home/alice"))
7715 When booting or upon completion of @command{guix system reconfigure},
7716 the system ensures that only the user accounts and groups specified in
7717 the @code{operating-system} declaration exist, and with the specified
7718 properties. Thus, account or group creations or modifications made by
7719 directly invoking commands such as @command{useradd} are lost upon
7720 reconfiguration or reboot. This ensures that the system remains exactly
7723 @deftp {Data Type} user-account
7724 Objects of this type represent user accounts. The following members may
7729 The name of the user account.
7733 This is the name (a string) or identifier (a number) of the user group
7734 this account belongs to.
7736 @item @code{supplementary-groups} (default: @code{'()})
7737 Optionally, this can be defined as a list of group names that this
7740 @item @code{uid} (default: @code{#f})
7741 This is the user ID for this account (a number), or @code{#f}. In the
7742 latter case, a number is automatically chosen by the system when the
7745 @item @code{comment} (default: @code{""})
7746 A comment about the account, such as the account owner's full name.
7748 @item @code{home-directory}
7749 This is the name of the home directory for the account.
7751 @item @code{create-home-directory?} (default: @code{#t})
7752 Indicates whether the home directory of this account should be created
7753 if it does not exist yet.
7755 @item @code{shell} (default: Bash)
7756 This is a G-expression denoting the file name of a program to be used as
7757 the shell (@pxref{G-Expressions}).
7759 @item @code{system?} (default: @code{#f})
7760 This Boolean value indicates whether the account is a ``system''
7761 account. System accounts are sometimes treated specially; for instance,
7762 graphical login managers do not list them.
7764 @anchor{user-account-password}
7765 @item @code{password} (default: @code{#f})
7766 You would normally leave this field to @code{#f}, initialize user
7767 passwords as @code{root} with the @command{passwd} command, and then let
7768 users change it with @command{passwd}. Passwords set with
7769 @command{passwd} are of course preserved across reboot and
7772 If you @emph{do} want to have a preset password for an account, then
7773 this field must contain the encrypted password, as a string.
7774 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
7775 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
7776 Manual}, for information on Guile's @code{crypt} procedure.
7782 User group declarations are even simpler:
7785 (user-group (name "students"))
7788 @deftp {Data Type} user-group
7789 This type is for, well, user groups. There are just a few fields:
7793 The name of the group.
7795 @item @code{id} (default: @code{#f})
7796 The group identifier (a number). If @code{#f}, a new number is
7797 automatically allocated when the group is created.
7799 @item @code{system?} (default: @code{#f})
7800 This Boolean value indicates whether the group is a ``system'' group.
7801 System groups have low numerical IDs.
7803 @item @code{password} (default: @code{#f})
7804 What, user groups can have a password? Well, apparently yes. Unless
7805 @code{#f}, this field specifies the password of the group.
7810 For convenience, a variable lists all the basic user groups one may
7813 @defvr {Scheme Variable} %base-groups
7814 This is the list of basic user groups that users and/or packages expect
7815 to be present on the system. This includes groups such as ``root'',
7816 ``wheel'', and ``users'', as well as groups used to control access to
7817 specific devices such as ``audio'', ``disk'', and ``cdrom''.
7820 @defvr {Scheme Variable} %base-user-accounts
7821 This is the list of basic system accounts that programs may expect to
7822 find on a GNU/Linux system, such as the ``nobody'' account.
7824 Note that the ``root'' account is not included here. It is a
7825 special-case and is automatically added whether or not it is specified.
7832 A @dfn{locale} defines cultural conventions for a particular language
7833 and region of the world (@pxref{Locales,,, libc, The GNU C Library
7834 Reference Manual}). Each locale has a name that typically has the form
7835 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
7836 @code{fr_LU.utf8} designates the locale for the French language, with
7837 cultural conventions from Luxembourg, and using the UTF-8 encoding.
7839 @cindex locale definition
7840 Usually, you will want to specify the default locale for the machine
7841 using the @code{locale} field of the @code{operating-system} declaration
7842 (@pxref{operating-system Reference, @code{locale}}).
7844 The selected locale is automatically added to the @dfn{locale
7845 definitions} known to the system if needed, with its codeset inferred
7846 from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
7847 @code{UTF-8} codeset. Additional locale definitions can be specified in
7848 the @code{locale-definitions} slot of @code{operating-system}---this is
7849 useful, for instance, if the codeset could not be inferred from the
7850 locale name. The default set of locale definitions includes some widely
7851 used locales, but not all the available locales, in order to save space.
7853 For instance, to add the North Frisian locale for Germany, the value of
7857 (cons (locale-definition
7858 (name "fy_DE.utf8") (source "fy_DE"))
7859 %default-locale-definitions)
7862 Likewise, to save space, one might want @code{locale-definitions} to
7863 list only the locales that are actually used, as in:
7866 (list (locale-definition
7867 (name "ja_JP.eucjp") (source "ja_JP")
7868 (charset "EUC-JP")))
7872 The compiled locale definitions are available at
7873 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
7874 version, which is the default location where the GNU@tie{}libc provided
7875 by Guix looks for locale data. This can be overridden using the
7876 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
7877 @code{LOCPATH} and locale packages}).
7879 The @code{locale-definition} form is provided by the @code{(gnu system
7880 locale)} module. Details are given below.
7882 @deftp {Data Type} locale-definition
7883 This is the data type of a locale definition.
7888 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
7889 Reference Manual}, for more information on locale names.
7892 The name of the source for that locale. This is typically the
7893 @code{@var{language}_@var{territory}} part of the locale name.
7895 @item @code{charset} (default: @code{"UTF-8"})
7896 The ``character set'' or ``code set'' for that locale,
7897 @uref{http://www.iana.org/assignments/character-sets, as defined by
7903 @defvr {Scheme Variable} %default-locale-definitions
7904 A list of commonly used UTF-8 locales, used as the default
7905 value of the @code{locale-definitions} field of @code{operating-system}
7909 @cindex normalized codeset in locale names
7910 These locale definitions use the @dfn{normalized codeset} for the part
7911 that follows the dot in the name (@pxref{Using gettextized software,
7912 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
7913 instance it has @code{uk_UA.utf8} but @emph{not}, say,
7917 @subsubsection Locale Data Compatibility Considerations
7919 @cindex incompatibility, of locale data
7920 @code{operating-system} declarations provide a @code{locale-libcs} field
7921 to specify the GNU@tie{}libc packages that are used to compile locale
7922 declarations (@pxref{operating-system Reference}). ``Why would I
7923 care?'', you may ask. Well, it turns out that the binary format of
7924 locale data is occasionally incompatible from one libc version to
7927 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
7928 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
7929 For instance, a program linked against libc version 2.21 is unable to
7930 read locale data produced with libc 2.22; worse, that program
7931 @emph{aborts} instead of simply ignoring the incompatible locale
7932 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
7933 the incompatible locale data, which is already an improvement.}.
7934 Similarly, a program linked against libc 2.22 can read most, but not
7935 all, of the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
7936 data is incompatible); thus calls to @code{setlocale} may fail, but
7937 programs will not abort.
7939 The ``problem'' in GuixSD is that users have a lot of freedom: They can
7940 choose whether and when to upgrade software in their profiles, and might
7941 be using a libc version different from the one the system administrator
7942 used to build the system-wide locale data.
7944 Fortunately, unprivileged users can also install their own locale data
7945 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
7946 @code{GUIX_LOCPATH} and locale packages}).
7948 Still, it is best if the system-wide locale data at
7949 @file{/run/current-system/locale} is built for all the libc versions
7950 actually in use on the system, so that all the programs can access
7951 it---this is especially crucial on a multi-user system. To do that, the
7952 administrator can specify several libc packages in the
7953 @code{locale-libcs} field of @code{operating-system}:
7956 (use-package-modules base)
7960 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
7963 This example would lead to a system containing locale definitions for
7964 both libc 2.21 and the current version of libc in
7965 @file{/run/current-system/locale}.
7969 @subsection Services
7971 @cindex system services
7972 An important part of preparing an @code{operating-system} declaration is
7973 listing @dfn{system services} and their configuration (@pxref{Using the
7974 Configuration System}). System services are typically daemons launched
7975 when the system boots, or other actions needed at that time---e.g.,
7976 configuring network access.
7978 GuixSD has a broad definition of ``service'' (@pxref{Service
7979 Composition}), but many services are managed by the GNU@tie{}Shepherd
7980 (@pxref{Shepherd Services}). On a running system, the @command{herd}
7981 command allows you to list the available services, show their status,
7982 start and stop them, or do other specific operations (@pxref{Jump
7983 Start,,, shepherd, The GNU Shepherd Manual}). For example:
7989 The above command, run as @code{root}, lists the currently defined
7990 services. The @command{herd doc} command shows a synopsis of the given
7995 Run libc's name service cache daemon (nscd).
7998 The @command{start}, @command{stop}, and @command{restart} sub-commands
7999 have the effect you would expect. For instance, the commands below stop
8000 the nscd service and restart the Xorg display server:
8004 Service nscd has been stopped.
8005 # herd restart xorg-server
8006 Service xorg-server has been stopped.
8007 Service xorg-server has been started.
8010 The following sections document the available services, starting with
8011 the core services, that may be used in an @code{operating-system}
8015 * Base Services:: Essential system services.
8016 * Scheduled Job Execution:: The mcron service.
8017 * Log Rotation:: The rottlog service.
8018 * Networking Services:: Network setup, SSH daemon, etc.
8019 * X Window:: Graphical display.
8020 * Printing Services:: Local and remote printer support.
8021 * Desktop Services:: D-Bus and desktop services.
8022 * Database Services:: SQL databases.
8023 * Mail Services:: IMAP, POP3, SMTP, and all that.
8024 * Kerberos Services:: Kerberos services.
8025 * Web Services:: Web servers.
8026 * Network File System:: NFS related services.
8027 * Continuous Integration:: The Cuirass service.
8028 * Miscellaneous Services:: Other services.
8032 @subsubsection Base Services
8034 The @code{(gnu services base)} module provides definitions for the basic
8035 services that one expects from the system. The services exported by
8036 this module are listed below.
8038 @defvr {Scheme Variable} %base-services
8039 This variable contains a list of basic services (@pxref{Service Types
8040 and Services}, for more information on service objects) one would
8041 expect from the system: a login service (mingetty) on each tty, syslogd,
8042 the libc name service cache daemon (nscd), the udev device manager, and
8045 This is the default value of the @code{services} field of
8046 @code{operating-system} declarations. Usually, when customizing a
8047 system, you will want to append services to @var{%base-services}, like
8051 (cons* (avahi-service) (lsh-service) %base-services)
8055 @deffn {Scheme Procedure} host-name-service @var{name}
8056 Return a service that sets the host name to @var{name}.
8059 @deffn {Scheme Procedure} login-service @var{config}
8060 Return a service to run login according to @var{config}, a
8061 @code{<login-configuration>} object, which specifies the message of the day,
8065 @deftp {Data Type} login-configuration
8066 This is the data type representing the configuration of login.
8071 @cindex message of the day
8072 A file-like object containing the ``message of the day''.
8074 @item @code{allow-empty-passwords?} (default: @code{#t})
8075 Allow empty passwords by default so that first-time users can log in when
8076 the 'root' account has just been created.
8081 @deffn {Scheme Procedure} mingetty-service @var{config}
8082 Return a service to run mingetty according to @var{config}, a
8083 @code{<mingetty-configuration>} object, which specifies the tty to run, among
8087 @deftp {Data Type} mingetty-configuration
8088 This is the data type representing the configuration of Mingetty, which
8089 implements console log-in.
8094 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
8096 @item @code{auto-login} (default: @code{#f})
8097 When true, this field must be a string denoting the user name under
8098 which the system automatically logs in. When it is @code{#f}, a
8099 user name and password must be entered to log in.
8101 @item @code{login-program} (default: @code{#f})
8102 This must be either @code{#f}, in which case the default log-in program
8103 is used (@command{login} from the Shadow tool suite), or a gexp denoting
8104 the name of the log-in program.
8106 @item @code{login-pause?} (default: @code{#f})
8107 When set to @code{#t} in conjunction with @var{auto-login}, the user
8108 will have to press a key before the log-in shell is launched.
8110 @item @code{mingetty} (default: @var{mingetty})
8111 The Mingetty package to use.
8116 @deffn {Scheme Procedure} kmscon-service-type @var{config}
8117 Return a service to run @uref{https://www.freedesktop.org/wiki/Software/kmscon,kmscon}
8118 according to @var{config}, a @code{<kmscon-configuration>} object, which
8119 specifies the tty to run, among other things.
8122 @deftp {Data Type} kmscon-configuration
8123 This is the data type representing the configuration of Kmscon, which
8124 implements console log-in.
8128 @item @code{virtual-terminal}
8129 The name of the console this Kmscon runs on---e.g., @code{"tty1"}.
8131 @item @code{login-program} (default: @code{#~(string-append #$shadow "/bin/login")})
8132 A gexp denoting the name of the log-in program. The default log-in program is
8133 @command{login} from the Shadow tool suite.
8135 @item @code{login-arguments} (default: @code{'("-p")})
8136 A list of arguments to pass to @command{login}.
8138 @item @code{hardware-acceleration?} (default: #f)
8139 Whether to use hardware acceleration.
8141 @item @code{kmscon} (default: @var{kmscon})
8142 The Kmscon package to use.
8147 @cindex name service cache daemon
8149 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
8150 [#:name-services '()]
8151 Return a service that runs the libc name service cache daemon (nscd) with the
8152 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
8153 Service Switch}, for an example.
8156 @defvr {Scheme Variable} %nscd-default-configuration
8157 This is the default @code{<nscd-configuration>} value (see below) used
8158 by @code{nscd-service}. It uses the caches defined by
8159 @var{%nscd-default-caches}; see below.
8162 @deftp {Data Type} nscd-configuration
8163 This is the data type representing the name service cache daemon (nscd)
8168 @item @code{name-services} (default: @code{'()})
8169 List of packages denoting @dfn{name services} that must be visible to
8170 the nscd---e.g., @code{(list @var{nss-mdns})}.
8172 @item @code{glibc} (default: @var{glibc})
8173 Package object denoting the GNU C Library providing the @command{nscd}
8176 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
8177 Name of the nscd log file. This is where debugging output goes when
8178 @code{debug-level} is strictly positive.
8180 @item @code{debug-level} (default: @code{0})
8181 Integer denoting the debugging levels. Higher numbers mean that more
8182 debugging output is logged.
8184 @item @code{caches} (default: @var{%nscd-default-caches})
8185 List of @code{<nscd-cache>} objects denoting things to be cached; see
8191 @deftp {Data Type} nscd-cache
8192 Data type representing a cache database of nscd and its parameters.
8196 @item @code{database}
8197 This is a symbol representing the name of the database to be cached.
8198 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
8199 @code{services}, which designate the corresponding NSS database
8200 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
8202 @item @code{positive-time-to-live}
8203 @itemx @code{negative-time-to-live} (default: @code{20})
8204 A number representing the number of seconds during which a positive or
8205 negative lookup result remains in cache.
8207 @item @code{check-files?} (default: @code{#t})
8208 Whether to check for updates of the files corresponding to
8211 For instance, when @var{database} is @code{hosts}, setting this flag
8212 instructs nscd to check for updates in @file{/etc/hosts} and to take
8215 @item @code{persistent?} (default: @code{#t})
8216 Whether the cache should be stored persistently on disk.
8218 @item @code{shared?} (default: @code{#t})
8219 Whether the cache should be shared among users.
8221 @item @code{max-database-size} (default: 32@tie{}MiB)
8222 Maximum size in bytes of the database cache.
8224 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
8225 @c settings, so leave them out.
8230 @defvr {Scheme Variable} %nscd-default-caches
8231 List of @code{<nscd-cache>} objects used by default by
8232 @code{nscd-configuration} (see above).
8234 It enables persistent and aggressive caching of service and host name
8235 lookups. The latter provides better host name lookup performance,
8236 resilience in the face of unreliable name servers, and also better
8237 privacy---often the result of host name lookups is in local cache, so
8238 external name servers do not even need to be queried.
8241 @anchor{syslog-configuration-type}
8244 @deftp {Data Type} syslog-configuration
8245 This data type represents the configuration of the syslog daemon.
8248 @item @code{syslogd} (default: @code{#~(string-append #$inetutils "/libexec/syslogd")})
8249 The syslog daemon to use.
8251 @item @code{config-file} (default: @code{%default-syslog.conf})
8252 The syslog configuration file to use.
8257 @anchor{syslog-service}
8259 @deffn {Scheme Procedure} syslog-service @var{config}
8260 Return a service that runs a syslog daemon according to @var{config}.
8262 @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more
8263 information on the configuration file syntax.
8266 @anchor{guix-configuration-type}
8267 @deftp {Data Type} guix-configuration
8268 This data type represents the configuration of the Guix build daemon.
8269 @xref{Invoking guix-daemon}, for more information.
8272 @item @code{guix} (default: @var{guix})
8273 The Guix package to use.
8275 @item @code{build-group} (default: @code{"guixbuild"})
8276 Name of the group for build user accounts.
8278 @item @code{build-accounts} (default: @code{10})
8279 Number of build user accounts to create.
8281 @item @code{authorize-key?} (default: @code{#t})
8282 @cindex substitutes, authorization thereof
8283 Whether to authorize the substitute keys listed in
8284 @code{authorized-keys}---by default that of @code{hydra.gnu.org}
8285 (@pxref{Substitutes}).
8287 @vindex %default-authorized-guix-keys
8288 @item @code{authorized-keys} (default: @var{%default-authorized-guix-keys})
8289 The list of authorized key files for archive imports, as a list of
8290 string-valued gexps (@pxref{Invoking guix archive}). By default, it
8291 contains that of @code{hydra.gnu.org} (@pxref{Substitutes}).
8293 @item @code{use-substitutes?} (default: @code{#t})
8294 Whether to use substitutes.
8296 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
8297 The list of URLs where to look for substitutes by default.
8299 @item @code{extra-options} (default: @code{'()})
8300 List of extra command-line options for @command{guix-daemon}.
8302 @item @code{lsof} (default: @var{lsof})
8303 @itemx @code{lsh} (default: @var{lsh})
8304 The lsof and lsh packages to use.
8309 @deffn {Scheme Procedure} guix-service @var{config}
8310 Return a service that runs the Guix build daemon according to
8314 @deffn {Scheme Procedure} udev-service [#:udev udev]
8315 Run @var{udev}, which populates the @file{/dev} directory dynamically.
8318 @deffn {Scheme Procedure} urandom-seed-service @var{#f}
8319 Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
8323 @defvr {Scheme Variable} %random-seed-file
8324 This is the name of the file where some random bytes are saved by
8325 @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
8326 It defaults to @file{/var/lib/random-seed}.
8331 @deffn {Scheme Procedure} console-keymap-service @var{files} ...
8332 @cindex keyboard layout
8333 Return a service to load console keymaps from @var{files} using
8334 @command{loadkeys} command. Most likely, you want to load some default
8335 keymap, which can be done like this:
8338 (console-keymap-service "dvorak")
8341 Or, for example, for a Swedish keyboard, you may need to combine
8342 the following keymaps:
8344 (console-keymap-service "se-lat6" "se-fi-lat6")
8347 Also you can specify a full file name (or file names) of your keymap(s).
8348 See @code{man loadkeys} for details.
8354 @deffn {Scheme Procedure} gpm-service [#:gpm @var{gpm}] @
8356 Run @var{gpm}, the general-purpose mouse daemon, with the given
8357 command-line @var{options}. GPM allows users to use the mouse in the console,
8358 notably to select, copy, and paste text. The default value of @var{options}
8359 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
8361 This service is not part of @var{%base-services}.
8364 @anchor{guix-publish-service}
8365 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
8366 [#:port 80] [#:host "localhost"]
8367 Return a service that runs @command{guix publish} listening on @var{host}
8368 and @var{port} (@pxref{Invoking guix publish}).
8370 This assumes that @file{/etc/guix} already contains a signing key pair as
8371 created by @command{guix archive --generate-key} (@pxref{Invoking guix
8372 archive}). If that is not the case, the service will fail to start.
8375 @anchor{rngd-service}
8376 @deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @
8377 [#:device "/dev/hwrng"]
8378 Return a service that runs the @command{rngd} program from @var{rng-tools}
8379 to add @var{device} to the kernel's entropy pool. The service will fail if
8380 @var{device} does not exist.
8383 @anchor{pam-limits-service}
8384 @cindex session limits
8387 @deffn {Scheme Procedure} pam-limits-service [#:limits @var{limits}]
8389 Return a service that installs a configuration file for the
8390 @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,
8391 @code{pam_limits} module}. The procedure optionally takes a list of
8392 @code{pam-limits-entry} values, which can be used to specify
8393 @code{ulimit} limits and nice priority limits to user sessions.
8395 The following limits definition sets two hard and soft limits for all
8396 login sessions of users in the @code{realtime} group:
8401 (pam-limits-entry "@@realtime" 'both 'rtprio 99)
8402 (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
8405 The first entry increases the maximum realtime priority for
8406 non-privileged processes; the second entry lifts any restriction of the
8407 maximum address space that can be locked in memory. These settings are
8408 commonly used for real-time audio systems.
8411 @node Scheduled Job Execution
8412 @subsubsection Scheduled Job Execution
8416 @cindex scheduling jobs
8417 The @code{(gnu services mcron)} module provides an interface to
8418 GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
8419 mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional
8420 Unix @command{cron} daemon; the main difference is that it is
8421 implemented in Guile Scheme, which provides a lot of flexibility when
8422 specifying the scheduling of jobs and their actions.
8424 The example below defines an operating system that runs the
8425 @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files})
8426 and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as
8427 well as the @command{mkid} command on behalf of an unprivileged user
8428 (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses
8429 gexps to introduce job definitions that are passed to mcron
8430 (@pxref{G-Expressions}).
8433 (use-modules (guix) (gnu) (gnu services mcron))
8434 (use-package-modules base idutils)
8436 (define updatedb-job
8437 ;; Run 'updatedb' at 3AM every day. Here we write the
8438 ;; job's action as a Scheme procedure.
8439 #~(job '(next-hour '(3))
8441 (execl (string-append #$findutils "/bin/updatedb")
8443 "--prunepaths=/tmp /var/tmp /gnu/store"))))
8445 (define garbage-collector-job
8446 ;; Collect garbage 5 minutes after midnight every day.
8447 ;; The job's action is a shell command.
8448 #~(job "5 0 * * *" ;Vixie cron syntax
8452 ;; Update the index database as user "charlie" at 12:15PM
8453 ;; and 19:15PM. This runs from the user's home directory.
8454 #~(job '(next-minute-from (next-hour '(12 19)) '(15))
8455 (string-append #$idutils "/bin/mkid src")
8460 (services (cons (mcron-service (list garbage-collector-job
8466 @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron},
8467 for more information on mcron job specifications. Below is the
8468 reference of the mcron service.
8470 @deffn {Scheme Procedure} mcron-service @var{jobs} [#:mcron @var{mcron2}]
8471 Return an mcron service running @var{mcron} that schedules @var{jobs}, a
8472 list of gexps denoting mcron job specifications.
8474 This is a shorthand for:
8476 (service mcron-service-type
8477 (mcron-configuration (mcron mcron) (jobs jobs)))
8481 @defvr {Scheme Variable} mcron-service-type
8482 This is the type of the @code{mcron} service, whose value is an
8483 @code{mcron-configuration} object.
8485 This service type can be the target of a service extension that provides
8486 it additional job specifications (@pxref{Service Composition}). In
8487 other words, it is possible to define services that provide additional
8491 @deftp {Data Type} mcron-configuration
8492 Data type representing the configuration of mcron.
8495 @item @code{mcron} (default: @var{mcron2})
8496 The mcron package to use.
8499 This is a list of gexps (@pxref{G-Expressions}), where each gexp
8500 corresponds to an mcron job specification (@pxref{Syntax, mcron job
8501 specifications,, mcron, GNU@tie{}mcron}).
8507 @subsubsection Log Rotation
8510 @cindex log rotation
8512 Log files such as those found in @file{/var/log} tend to grow endlessly,
8513 so it's a good idea to @dfn{rotate} them once in a while---i.e., archive
8514 their contents in separate files, possibly compressed. The @code{(gnu
8515 services admin)} module provides an interface to GNU@tie{}Rot[t]log, a
8516 log rotation tool (@pxref{Top,,, rottlog, GNU Rot[t]log Manual}).
8518 The example below defines an operating system that provides log rotation
8519 with the default settings.
8522 (use-modules (guix) (gnu))
8523 (use-service-modules admin mcron)
8524 (use-package-modules base idutils)
8528 (services (cons* (mcron-service)
8529 (service rottlog-service-type (rottlog-configuration))
8533 @defvr {Scheme Variable} rottlog-service-type
8534 This is the type of the Rottlog service, whose value is a
8535 @code{rottlog-configuration} object.
8537 This service type can define mcron jobs (@pxref{Scheduled Job
8538 Execution}) to run the rottlog service.
8541 @deftp {Data Type} rottlog-configuration
8542 Data type representing the configuration of rottlog.
8545 @item @code{rottlog} (default: @code{rottlog})
8546 The Rottlog package to use.
8548 @item @code{rc-file} (default: @code{(file-append rottlog "/etc/rc")})
8549 The Rottlog configuration file to use (@pxref{Mandatory RC Variables,,,
8550 rottlog, GNU Rot[t]log Manual}).
8552 @item @code{periodic-rotations} (default: @code{`(("weekly" %default-rotatations))})
8553 A list of Rottlog period-name/period-config tuples.
8555 For example, taking an example from the Rottlog manual (@pxref{Period
8556 Related File Examples,,, rottlog, GNU Rot[t]log Manual}), a valid tuple
8560 ("daily" ,(plain-file "daily"
8562 /var/log/apache/* @{
8563 storedir apache-archives
8571 This is a list of gexps where each gexp corresponds to an mcron job
8572 specification (@pxref{Scheduled Job Execution}).
8576 @defvr {Scheme Variable} %default-rotations
8577 Specifies weekly rotation of @var{%rotated-files} and
8578 @code{"/var/log/shepherd.log"}.
8581 @defvr {Scheme Variable} %rotated-files
8582 The list of syslog-controlled files to be rotated. By default it is:
8583 @code{'("/var/log/messages" "/var/log/secure")}.
8586 @node Networking Services
8587 @subsubsection Networking Services
8589 The @code{(gnu services networking)} module provides services to configure
8590 the network interface.
8592 @cindex DHCP, networking service
8593 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
8594 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
8595 Protocol (DHCP) client, on all the non-loopback network interfaces.
8598 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
8599 [#:netmask #f] [#:gateway #f] [#:name-servers @code{'()}]
8600 Return a service that starts @var{interface} with address @var{ip}. If
8601 @var{netmask} is true, use it as the network mask. If @var{gateway} is true,
8602 it must be a string specifying the default network gateway.
8608 @cindex network management
8609 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
8610 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
8611 management daemon that aims to simplify wired and wireless networking.
8613 This service adds the @var{wicd} package to the global profile, providing
8614 several commands to interact with the daemon and configure networking:
8615 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
8616 and @command{wicd-curses} user interfaces.
8619 @cindex NetworkManager
8620 @deffn {Scheme Procedure} network-manager-service @
8621 [#:network-manager @var{network-manager}]
8622 Return a service that runs NetworkManager, a network connection manager
8623 attempting to keep network connectivity active when available.
8627 @deffn {Scheme Procedure} connman-service @
8628 [#:connman @var{connman}]
8629 Return a service that runs @url{https://01.org/connman,Connman}, a network
8632 This service adds the @var{connman} package to the global profile, providing
8633 several the @command{connmanctl} command to interact with the daemon and
8634 configure networking."
8637 @cindex WPA Supplicant
8638 @defvr {Scheme Variable} wpa-supplicant-service-type
8639 This is the service type to run @url{https://w1.fi/wpa_supplicant/,WPA
8640 supplicant}, an authentication daemon required to authenticate against
8641 encrypted WiFi or ethernet networks. It is configured to listen for
8644 The value of this service is the @code{wpa-supplicant} package to use.
8645 Thus, it can be instantiated like this:
8648 (use-modules (gnu services networking)
8649 (gnu packages admin))
8651 (service wpa-supplicant-service-type wpa-supplicant)
8656 @cindex real time clock
8657 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
8658 [#:servers @var{%ntp-servers}] @
8659 [#:allow-large-adjustment? #f]
8660 Return a service that runs the daemon from @var{ntp}, the
8661 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
8662 keep the system clock synchronized with that of @var{servers}.
8663 @var{allow-large-adjustment?} determines whether @command{ntpd} is allowed to
8664 make an initial adjustment of more than 1,000 seconds.
8667 @defvr {Scheme Variable} %ntp-servers
8668 List of host names used as the default NTP servers.
8672 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
8673 Return a service to run the @uref{https://torproject.org, Tor} anonymous
8676 The daemon runs as the @code{tor} unprivileged user. It is passed
8677 @var{config-file}, a file-like object, with an additional @code{User tor} line
8678 and lines for hidden services added via @code{tor-hidden-service}. Run
8679 @command{man tor} for information about the configuration file.
8682 @cindex hidden service
8683 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
8684 Define a new Tor @dfn{hidden service} called @var{name} and implementing
8685 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
8688 '((22 "127.0.0.1:22")
8689 (80 "127.0.0.1:8080"))
8692 In this example, port 22 of the hidden service is mapped to local port 22, and
8693 port 80 is mapped to local port 8080.
8695 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
8696 the @file{hostname} file contains the @code{.onion} host name for the hidden
8699 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
8700 project's documentation} for more information.
8703 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
8704 [#:interface "127.0.0.1"] [#:port 6667] @
8705 [#:extra-settings ""]
8706 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
8707 acts as a gateway between IRC and chat networks.
8709 The daemon will listen to the interface corresponding to the IP address
8710 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
8711 local clients can connect, whereas @code{0.0.0.0} means that connections can
8712 come from any networking interface.
8714 In addition, @var{extra-settings} specifies a string to append to the
8718 Furthermore, @code{(gnu services ssh)} provides the following services.
8722 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
8723 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
8724 [#:allow-empty-passwords? #f] [#:root-login? #f] @
8725 [#:syslog-output? #t] [#:x11-forwarding? #t] @
8726 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
8727 [#:public-key-authentication? #t] [#:initialize? #t]
8728 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
8729 @var{host-key} must designate a file containing the host key, and readable
8732 When @var{daemonic?} is true, @command{lshd} will detach from the
8733 controlling terminal and log its output to syslogd, unless one sets
8734 @var{syslog-output?} to false. Obviously, it also makes lsh-service
8735 depend on existence of syslogd service. When @var{pid-file?} is true,
8736 @command{lshd} writes its PID to the file called @var{pid-file}.
8738 When @var{initialize?} is true, automatically create the seed and host key
8739 upon service activation if they do not exist yet. This may take long and
8740 require interaction.
8742 When @var{initialize?} is false, it is up to the user to initialize the
8743 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
8744 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
8745 basics,,, lsh, LSH Manual}).
8747 When @var{interfaces} is empty, lshd listens for connections on all the
8748 network interfaces; otherwise, @var{interfaces} must be a list of host names
8751 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
8752 passwords, and @var{root-login?} specifies whether to accept log-ins as
8755 The other options should be self-descriptive.
8760 @deffn {Scheme Variable} openssh-service-type
8761 This is the type for the @uref{http://www.openssh.org, OpenSSH} secure
8762 shell daemon, @command{sshd}. Its value must be an
8763 @code{openssh-configuration} record as in this example:
8766 (service openssh-service-type
8767 (openssh-configuration
8768 (x11-forwarding? #t)
8769 (permit-root-login 'without-password)))
8772 See below for details about @code{openssh-configuration}.
8775 @deftp {Data Type} openssh-configuration
8776 This is the configuration record for OpenSSH's @command{sshd}.
8779 @item @code{pid-file} (default: @code{"/var/run/sshd.pid"})
8780 Name of the file where @command{sshd} writes its PID.
8782 @item @code{port-number} (default: @code{22})
8783 TCP port on which @command{sshd} listens for incoming connections.
8785 @item @code{permit-root-login} (default: @code{#f})
8786 This field determines whether and when to allow logins as root. If
8787 @code{#f}, root logins are disallowed; if @code{#t}, they are allowed.
8788 If it's the symbol @code{'without-password}, then root logins are
8789 permitted but not with password-based authentication.
8791 @item @code{allow-empty-passwords?} (default: @code{#f})
8792 When true, users with empty passwords may log in. When false, they may
8795 @item @code{password-authentication?} (default: @code{#t})
8796 When true, users may log in with their password. When false, they have
8797 other authentication methods.
8799 @item @code{public-key-authentication?} (default: @code{#t})
8800 When true, users may log in using public key authentication. When
8801 false, users have to use other authentication method.
8803 Authorized public keys are stored in @file{~/.ssh/authorized_keys}.
8804 This is used only by protocol version 2.
8806 @item @code{rsa-authentication?} (default: @code{#t})
8807 When true, users may log in using pure RSA authentication. When false,
8808 users have to use other means of authentication. This is used only by
8811 @item @code{x11-forwarding?} (default: @code{#f})
8812 When true, forwarding of X11 graphical client connections is
8813 enabled---in other words, @command{ssh} options @option{-X} and
8814 @option{-Y} will work.
8816 @item @code{protocol-number} (default: @code{2})
8817 The SSH protocol number to use.
8821 @deffn {Scheme Procedure} dropbear-service [@var{config}]
8822 Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
8823 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
8826 For example, to specify a Dropbear service listening on port 1234, add
8827 this call to the operating system's @code{services} field:
8830 (dropbear-service (dropbear-configuration
8831 (port-number 1234)))
8835 @deftp {Data Type} dropbear-configuration
8836 This data type represents the configuration of a Dropbear SSH daemon.
8839 @item @code{dropbear} (default: @var{dropbear})
8840 The Dropbear package to use.
8842 @item @code{port-number} (default: 22)
8843 The TCP port where the daemon waits for incoming connections.
8845 @item @code{syslog-output?} (default: @code{#t})
8846 Whether to enable syslog output.
8848 @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"})
8849 File name of the daemon's PID file.
8851 @item @code{root-login?} (default: @code{#f})
8852 Whether to allow @code{root} logins.
8854 @item @code{allow-empty-passwords?} (default: @code{#f})
8855 Whether to allow empty passwords.
8857 @item @code{password-authentication?} (default: @code{#t})
8858 Whether to enable password-based authentication.
8862 @defvr {Scheme Variable} %facebook-host-aliases
8863 This variable contains a string for use in @file{/etc/hosts}
8864 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
8865 line contains a entry that maps a known server name of the Facebook
8866 on-line service---e.g., @code{www.facebook.com}---to the local
8867 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
8869 This variable is typically used in the @code{hosts-file} field of an
8870 @code{operating-system} declaration (@pxref{operating-system Reference,
8871 @file{/etc/hosts}}):
8874 (use-modules (gnu) (guix))
8877 (host-name "mymachine")
8880 ;; Create a /etc/hosts file with aliases for "localhost"
8881 ;; and "mymachine", as well as for Facebook servers.
8883 (string-append (local-host-aliases host-name)
8884 %facebook-host-aliases))))
8887 This mechanism can prevent programs running locally, such as Web
8888 browsers, from accessing Facebook.
8891 The @code{(gnu services avahi)} provides the following definition.
8893 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
8894 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
8895 [#:ipv6? #t] [#:wide-area? #f] @
8896 [#:domains-to-browse '()] [#:debug? #f]
8897 Return a service that runs @command{avahi-daemon}, a system-wide
8898 mDNS/DNS-SD responder that allows for service discovery and
8899 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
8900 extends the name service cache daemon (nscd) so that it can resolve
8901 @code{.local} host names using
8902 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
8903 add the @var{avahi} package to the system profile so that commands such as
8904 @command{avahi-browse} are directly usable.
8906 If @var{host-name} is different from @code{#f}, use that as the host name to
8907 publish for this machine; otherwise, use the machine's actual host name.
8909 When @var{publish?} is true, publishing of host names and services is allowed;
8910 in particular, avahi-daemon will publish the machine's host name and IP
8911 address via mDNS on the local network.
8913 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
8915 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
8921 @subsubsection X Window
8924 @cindex X Window System
8925 Support for the X Window graphical display system---specifically
8926 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
8927 there is no @code{xorg-service} procedure. Instead, the X server is
8928 started by the @dfn{login manager}, currently SLiM.
8930 @deftp {Data Type} sddm-configuration
8931 This is the data type representing the sddm service configuration.
8934 @item @code{display-server} (default: "x11")
8935 Select display server to use for the greeter. Valid values are "x11"
8938 @item @code{numlock} (default: "on")
8939 Valid values are "on", "off" or "none".
8941 @item @code{halt-command} (default @code{#~(string-apppend #$shepherd "/sbin/halt")})
8942 Command to run when halting.
8944 @item @code{reboot-command} (default @code{#~(string-append #$shepherd "/sbin/reboot")})
8945 Command to run when rebooting.
8947 @item @code{theme} (default "maldives")
8948 Theme to use. Default themes provided by SDDM are "elarun" or "maldives".
8950 @item @code{themes-directory} (default "/run/current-system/profile/share/sddm/themes")
8951 Directory to look for themes.
8953 @item @code{faces-directory} (default "/run/current-system/profile/share/sddm/faces")
8954 Directory to look for faces.
8956 @item @code{default-path} (default "/run/current-system/profile/bin")
8957 Default PATH to use.
8959 @item @code{minimum-uid} (default 1000)
8960 Minimum UID to display in SDDM.
8962 @item @code{maximum-uid} (default 2000)
8963 Maximum UID to display in SDDM
8965 @item @code{remember-last-user?} (default #t)
8968 @item @code{remember-last-session?} (default #t)
8969 Remember last session.
8971 @item @code{hide-users} (default "")
8972 Usernames to hide from SDDM greeter.
8974 @item @code{hide-shells} (default @code{#~(string-append #$shadow "/sbin/nologin")})
8975 Users with shells listed will be hidden from the SDDM greeter.
8977 @item @code{session-command} (default @code{#~(string-append #$sddm "/share/sddm/scripts/wayland-session")})
8978 Script to run before starting a wayland session.
8980 @item @code{sessions-directory} (default "/run/current-system/profile/share/wayland-sessions")
8981 Directory to look for desktop files starting wayland sessions.
8983 @item @code{xorg-server-path} (default @code{xorg-start-command})
8984 Path to xorg-server.
8986 @item @code{xauth-path} (default @code{#~(string-append #$xauth "/bin/xauth")})
8989 @item @code{xephyr-path} (default @code{#~(string-append #$xorg-server "/bin/Xephyr")})
8992 @item @code{xdisplay-start} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xsetup")})
8993 Script to run after starting xorg-server.
8995 @item @code{xdisplay-stop} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xstop")})
8996 Script to run before stopping xorg-server.
8998 @item @code{xsession-command} (default: @code{xinitr })
8999 Script to run before starting a X session.
9001 @item @code{xsessions-directory} (default: "/run/current-system/profile/share/xsessions")
9002 Directory to look for desktop files starting X sessions.
9004 @item @code{minimum-vt} (default: 7)
9007 @item @code{xserver-arguments} (default "-nolisten tcp")
9008 Arguments to pass to xorg-server.
9010 @item @code{auto-login-user} (default "")
9011 User to use for auto-login.
9013 @item @code{auto-login-session} (default "")
9014 Desktop file to use for auto-login.
9016 @item @code{relogin?} (default #f)
9017 Relogin after logout.
9022 @cindex login manager
9023 @deffn {Scheme Procedure} sddm-service config
9024 Return a service that spawns the SDDM graphical login manager for config of
9025 type @code{<sddm-configuration>}.
9028 (sddm-service (sddm-configuration
9029 (auto-login-user "Alice")
9030 (auto-login-session "xfce.desktop")))
9034 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
9035 [#:auto-login? #f] [#:default-user ""] [#:startx] @
9036 [#:theme @var{%default-slim-theme}] @
9037 [#:theme-name @var{%default-slim-theme-name}]
9038 Return a service that spawns the SLiM graphical login manager, which in
9039 turn starts the X display server with @var{startx}, a command as returned by
9040 @code{xorg-start-command}.
9044 SLiM automatically looks for session types described by the @file{.desktop}
9045 files in @file{/run/current-system/profile/share/xsessions} and allows users
9046 to choose a session from the log-in screen using @kbd{F1}. Packages such as
9047 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
9048 adding them to the system-wide set of packages automatically makes them
9049 available at the log-in screen.
9051 In addition, @file{~/.xsession} files are honored. When available,
9052 @file{~/.xsession} must be an executable that starts a window manager
9053 and/or other X clients.
9055 When @var{allow-empty-passwords?} is true, allow logins with an empty
9056 password. When @var{auto-login?} is true, log in automatically as
9059 If @var{theme} is @code{#f}, use the default log-in theme; otherwise
9060 @var{theme} must be a gexp denoting the name of a directory containing the
9061 theme to use. In that case, @var{theme-name} specifies the name of the
9065 @defvr {Scheme Variable} %default-theme
9066 @defvrx {Scheme Variable} %default-theme-name
9067 The G-Expression denoting the default SLiM theme and its name.
9070 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
9071 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
9072 Return a derivation that builds a @var{guile} script to start the X server
9073 from @var{xorg-server}. @var{configuration-file} is the server configuration
9074 file or a derivation that builds it; when omitted, the result of
9075 @code{xorg-configuration-file} is used.
9077 Usually the X server is started by a login manager.
9080 @deffn {Scheme Procedure} xorg-configuration-file @
9081 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
9082 Return a configuration file for the Xorg server containing search paths for
9083 all the common drivers.
9085 @var{drivers} must be either the empty list, in which case Xorg chooses a
9086 graphics driver automatically, or a list of driver names that will be tried in
9087 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
9089 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
9090 appropriate screen resolution; otherwise, it must be a list of
9091 resolutions---e.g., @code{((1024 768) (640 480))}.
9093 Last, @var{extra-config} is a list of strings or objects appended to the
9094 @code{text-file*} argument list. It is used to pass extra text to be added
9095 verbatim to the configuration file.
9098 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
9099 Add @var{package}, a package for a screen-locker or screen-saver whose
9100 command is @var{program}, to the set of setuid programs and add a PAM entry
9101 for it. For example:
9104 (screen-locker-service xlockmore "xlock")
9107 makes the good ol' XlockMore usable.
9111 @node Printing Services
9112 @subsubsection Printing Services
9114 The @code{(gnu services cups)} module provides a Guix service definition
9115 for the CUPS printing service. To add printer support to a GuixSD
9116 system, add a @code{cups-service} to the operating system definition:
9118 @deffn {Scheme Variable} cups-service-type
9119 The service type for the CUPS print server. Its value should be a valid
9120 CUPS configuration (see below). For example:
9122 (service cups-service-type (cups-configuration))
9126 The CUPS configuration controls the basic things about your CUPS
9127 installation: what interfaces it listens on, what to do if a print job
9128 fails, how much logging to do, and so on. To actually add a printer,
9129 you have to visit the @url{http://localhost:631} URL, or use a tool such
9130 as GNOME's printer configuration services. By default, configuring a
9131 CUPS service will generate a self-signed certificate if needed, for
9132 secure connections to the print server.
9134 One way you might want to customize CUPS is to enable or disable the web
9135 interface. You can do that directly, like this:
9138 (service cups-service-type
9140 (web-interface? #f)))
9143 The available configuration parameters follow. Each parameter
9144 definition is preceded by its type; for example, @samp{string-list foo}
9145 indicates that the @code{foo} parameter should be specified as a list of
9146 strings. There is also a way to specify the configuration as a string,
9147 if you have an old @code{cupsd.conf} file that you want to port over
9148 from some other system; see the end for more details.
9150 @c The following documentation was initially generated by
9151 @c (generate-documentation) in (gnu services cups). Manually maintained
9152 @c documentation is better, so we shouldn't hesitate to edit below as
9153 @c needed. However if the change you want to make to this documentation
9154 @c can be done in an automated way, it's probably easier to change
9155 @c (generate-documentation) than to make it below and have to deal with
9156 @c the churn as CUPS updates.
9159 Available @code{cups-configuration} fields are:
9161 @deftypevr {@code{cups-configuration} parameter} package cups
9165 @deftypevr {@code{cups-configuration} parameter} package-list extensions
9166 Drivers and other extensions to the CUPS package.
9169 @deftypevr {@code{cups-configuration} parameter} files-configuration files-configuration
9170 Configuration of where to write logs, what directories to use for print
9171 spools, and related privileged configuration parameters.
9173 Available @code{files-configuration} fields are:
9175 @deftypevr {@code{files-configuration} parameter} log-location access-log
9176 Defines the access log filename. Specifying a blank filename disables
9177 access log generation. The value @code{stderr} causes log entries to be
9178 sent to the standard error file when the scheduler is running in the
9179 foreground, or to the system log daemon when run in the background. The
9180 value @code{syslog} causes log entries to be sent to the system log
9181 daemon. The server name may be included in filenames using the string
9182 @code{%s}, as in @code{/var/log/cups/%s-access_log}.
9184 Defaults to @samp{"/var/log/cups/access_log"}.
9187 @deftypevr {@code{files-configuration} parameter} file-name cache-dir
9188 Where CUPS should cache data.
9190 Defaults to @samp{"/var/cache/cups"}.
9193 @deftypevr {@code{files-configuration} parameter} string config-file-perm
9194 Specifies the permissions for all configuration files that the scheduler
9197 Note that the permissions for the printers.conf file are currently
9198 masked to only allow access from the scheduler user (typically root).
9199 This is done because printer device URIs sometimes contain sensitive
9200 authentication information that should not be generally known on the
9201 system. There is no way to disable this security feature.
9203 Defaults to @samp{"0640"}.
9206 @deftypevr {@code{files-configuration} parameter} log-location error-log
9207 Defines the error log filename. Specifying a blank filename disables
9208 access log generation. The value @code{stderr} causes log entries to be
9209 sent to the standard error file when the scheduler is running in the
9210 foreground, or to the system log daemon when run in the background. The
9211 value @code{syslog} causes log entries to be sent to the system log
9212 daemon. The server name may be included in filenames using the string
9213 @code{%s}, as in @code{/var/log/cups/%s-error_log}.
9215 Defaults to @samp{"/var/log/cups/error_log"}.
9218 @deftypevr {@code{files-configuration} parameter} string fatal-errors
9219 Specifies which errors are fatal, causing the scheduler to exit. The
9224 No errors are fatal.
9227 All of the errors below are fatal.
9230 Browsing initialization errors are fatal, for example failed connections
9231 to the DNS-SD daemon.
9234 Configuration file syntax errors are fatal.
9237 Listen or Port errors are fatal, except for IPv6 failures on the
9238 loopback or @code{any} addresses.
9241 Log file creation or write errors are fatal.
9244 Bad startup file permissions are fatal, for example shared TLS
9245 certificate and key files with world-read permissions.
9248 Defaults to @samp{"all -browse"}.
9251 @deftypevr {@code{files-configuration} parameter} boolean file-device?
9252 Specifies whether the file pseudo-device can be used for new printer
9253 queues. The URI @uref{file:///dev/null} is always allowed.
9255 Defaults to @samp{#f}.
9258 @deftypevr {@code{files-configuration} parameter} string group
9259 Specifies the group name or ID that will be used when executing external
9262 Defaults to @samp{"lp"}.
9265 @deftypevr {@code{files-configuration} parameter} string log-file-perm
9266 Specifies the permissions for all log files that the scheduler writes.
9268 Defaults to @samp{"0644"}.
9271 @deftypevr {@code{files-configuration} parameter} log-location page-log
9272 Defines the page log filename. Specifying a blank filename disables
9273 access log generation. The value @code{stderr} causes log entries to be
9274 sent to the standard error file when the scheduler is running in the
9275 foreground, or to the system log daemon when run in the background. The
9276 value @code{syslog} causes log entries to be sent to the system log
9277 daemon. The server name may be included in filenames using the string
9278 @code{%s}, as in @code{/var/log/cups/%s-page_log}.
9280 Defaults to @samp{"/var/log/cups/page_log"}.
9283 @deftypevr {@code{files-configuration} parameter} string remote-root
9284 Specifies the username that is associated with unauthenticated accesses
9285 by clients claiming to be the root user. The default is @code{remroot}.
9287 Defaults to @samp{"remroot"}.
9290 @deftypevr {@code{files-configuration} parameter} file-name request-root
9291 Specifies the directory that contains print jobs and other HTTP request
9294 Defaults to @samp{"/var/spool/cups"}.
9297 @deftypevr {@code{files-configuration} parameter} sandboxing sandboxing
9298 Specifies the level of security sandboxing that is applied to print
9299 filters, backends, and other child processes of the scheduler; either
9300 @code{relaxed} or @code{strict}. This directive is currently only
9301 used/supported on macOS.
9303 Defaults to @samp{strict}.
9306 @deftypevr {@code{files-configuration} parameter} file-name server-keychain
9307 Specifies the location of TLS certificates and private keys. CUPS will
9308 look for public and private keys in this directory: a @code{.crt} files
9309 for PEM-encoded certificates and corresponding @code{.key} files for
9310 PEM-encoded private keys.
9312 Defaults to @samp{"/etc/cups/ssl"}.
9315 @deftypevr {@code{files-configuration} parameter} file-name server-root
9316 Specifies the directory containing the server configuration files.
9318 Defaults to @samp{"/etc/cups"}.
9321 @deftypevr {@code{files-configuration} parameter} boolean sync-on-close?
9322 Specifies whether the scheduler calls fsync(2) after writing
9323 configuration or state files.
9325 Defaults to @samp{#f}.
9328 @deftypevr {@code{files-configuration} parameter} space-separated-string-list system-group
9329 Specifies the group(s) to use for @code{@@SYSTEM} group authentication.
9332 @deftypevr {@code{files-configuration} parameter} file-name temp-dir
9333 Specifies the directory where temporary files are stored.
9335 Defaults to @samp{"/var/spool/cups/tmp"}.
9338 @deftypevr {@code{files-configuration} parameter} string user
9339 Specifies the user name or ID that is used when running external
9342 Defaults to @samp{"lp"}.
9346 @deftypevr {@code{cups-configuration} parameter} access-log-level access-log-level
9347 Specifies the logging level for the AccessLog file. The @code{config}
9348 level logs when printers and classes are added, deleted, or modified and
9349 when configuration files are accessed or updated. The @code{actions}
9350 level logs when print jobs are submitted, held, released, modified, or
9351 canceled, and any of the conditions for @code{config}. The @code{all}
9352 level logs all requests.
9354 Defaults to @samp{actions}.
9357 @deftypevr {@code{cups-configuration} parameter} boolean auto-purge-jobs?
9358 Specifies whether to purge job history data automatically when it is no
9359 longer required for quotas.
9361 Defaults to @samp{#f}.
9364 @deftypevr {@code{cups-configuration} parameter} browse-local-protocols browse-local-protocols
9365 Specifies which protocols to use for local printer sharing.
9367 Defaults to @samp{dnssd}.
9370 @deftypevr {@code{cups-configuration} parameter} boolean browse-web-if?
9371 Specifies whether the CUPS web interface is advertised.
9373 Defaults to @samp{#f}.
9376 @deftypevr {@code{cups-configuration} parameter} boolean browsing?
9377 Specifies whether shared printers are advertised.
9379 Defaults to @samp{#f}.
9382 @deftypevr {@code{cups-configuration} parameter} string classification
9383 Specifies the security classification of the server. Any valid banner
9384 name can be used, including "classified", "confidential", "secret",
9385 "topsecret", and "unclassified", or the banner can be omitted to disable
9386 secure printing functions.
9388 Defaults to @samp{""}.
9391 @deftypevr {@code{cups-configuration} parameter} boolean classify-override?
9392 Specifies whether users may override the classification (cover page) of
9393 individual print jobs using the @code{job-sheets} option.
9395 Defaults to @samp{#f}.
9398 @deftypevr {@code{cups-configuration} parameter} default-auth-type default-auth-type
9399 Specifies the default type of authentication to use.
9401 Defaults to @samp{Basic}.
9404 @deftypevr {@code{cups-configuration} parameter} default-encryption default-encryption
9405 Specifies whether encryption will be used for authenticated requests.
9407 Defaults to @samp{Required}.
9410 @deftypevr {@code{cups-configuration} parameter} string default-language
9411 Specifies the default language to use for text and web content.
9413 Defaults to @samp{"en"}.
9416 @deftypevr {@code{cups-configuration} parameter} string default-paper-size
9417 Specifies the default paper size for new print queues. @samp{"Auto"}
9418 uses a locale-specific default, while @samp{"None"} specifies there is
9419 no default paper size. Specific size names are typically
9420 @samp{"Letter"} or @samp{"A4"}.
9422 Defaults to @samp{"Auto"}.
9425 @deftypevr {@code{cups-configuration} parameter} string default-policy
9426 Specifies the default access policy to use.
9428 Defaults to @samp{"default"}.
9431 @deftypevr {@code{cups-configuration} parameter} boolean default-shared?
9432 Specifies whether local printers are shared by default.
9434 Defaults to @samp{#t}.
9437 @deftypevr {@code{cups-configuration} parameter} non-negative-integer dirty-clean-interval
9438 Specifies the delay for updating of configuration and state files, in
9439 seconds. A value of 0 causes the update to happen as soon as possible,
9440 typically within a few milliseconds.
9442 Defaults to @samp{30}.
9445 @deftypevr {@code{cups-configuration} parameter} error-policy error-policy
9446 Specifies what to do when an error occurs. Possible values are
9447 @code{abort-job}, which will discard the failed print job;
9448 @code{retry-job}, which will retry the job at a later time;
9449 @code{retry-this-job}, which retries the failed job immediately; and
9450 @code{stop-printer}, which stops the printer.
9452 Defaults to @samp{stop-printer}.
9455 @deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-limit
9456 Specifies the maximum cost of filters that are run concurrently, which
9457 can be used to minimize disk, memory, and CPU resource problems. A
9458 limit of 0 disables filter limiting. An average print to a
9459 non-PostScript printer needs a filter limit of about 200. A PostScript
9460 printer needs about half that (100). Setting the limit below these
9461 thresholds will effectively limit the scheduler to printing a single job
9464 Defaults to @samp{0}.
9467 @deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-nice
9468 Specifies the scheduling priority of filters that are run to print a
9469 job. The nice value ranges from 0, the highest priority, to 19, the
9472 Defaults to @samp{0}.
9475 @deftypevr {@code{cups-configuration} parameter} host-name-lookups host-name-lookups
9476 Specifies whether to do reverse lookups on connecting clients. The
9477 @code{double} setting causes @code{cupsd} to verify that the hostname
9478 resolved from the address matches one of the addresses returned for that
9479 hostname. Double lookups also prevent clients with unregistered
9480 addresses from connecting to your server. Only set this option to
9481 @code{#t} or @code{double} if absolutely required.
9483 Defaults to @samp{#f}.
9486 @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-kill-delay
9487 Specifies the number of seconds to wait before killing the filters and
9488 backend associated with a canceled or held job.
9490 Defaults to @samp{30}.
9493 @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-interval
9494 Specifies the interval between retries of jobs in seconds. This is
9495 typically used for fax queues but can also be used with normal print
9496 queues whose error policy is @code{retry-job} or
9497 @code{retry-current-job}.
9499 Defaults to @samp{30}.
9502 @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-limit
9503 Specifies the number of retries that are done for jobs. This is
9504 typically used for fax queues but can also be used with normal print
9505 queues whose error policy is @code{retry-job} or
9506 @code{retry-current-job}.
9508 Defaults to @samp{5}.
9511 @deftypevr {@code{cups-configuration} parameter} boolean keep-alive?
9512 Specifies whether to support HTTP keep-alive connections.
9514 Defaults to @samp{#t}.
9517 @deftypevr {@code{cups-configuration} parameter} non-negative-integer keep-alive-timeout
9518 Specifies how long an idle client connection remains open, in seconds.
9520 Defaults to @samp{30}.
9523 @deftypevr {@code{cups-configuration} parameter} non-negative-integer limit-request-body
9524 Specifies the maximum size of print files, IPP requests, and HTML form
9525 data. A limit of 0 disables the limit check.
9527 Defaults to @samp{0}.
9530 @deftypevr {@code{cups-configuration} parameter} multiline-string-list listen
9531 Listens on the specified interfaces for connections. Valid values are
9532 of the form @var{address}:@var{port}, where @var{address} is either an
9533 IPv6 address enclosed in brackets, an IPv4 address, or @code{*} to
9534 indicate all addresses. Values can also be file names of local UNIX
9535 domain sockets. The Listen directive is similar to the Port directive
9536 but allows you to restrict access to specific interfaces or networks.
9539 @deftypevr {@code{cups-configuration} parameter} non-negative-integer listen-back-log
9540 Specifies the number of pending connections that will be allowed. This
9541 normally only affects very busy servers that have reached the MaxClients
9542 limit, but can also be triggered by large numbers of simultaneous
9543 connections. When the limit is reached, the operating system will
9544 refuse additional connections until the scheduler can accept the pending
9547 Defaults to @samp{128}.
9550 @deftypevr {@code{cups-configuration} parameter} location-access-control-list location-access-controls
9551 Specifies a set of additional access controls.
9553 Available @code{location-access-controls} fields are:
9555 @deftypevr {@code{location-access-controls} parameter} file-name path
9556 Specifies the URI path to which the access control applies.
9559 @deftypevr {@code{location-access-controls} parameter} access-control-list access-controls
9560 Access controls for all access to this path, in the same format as the
9561 @code{access-controls} of @code{operation-access-control}.
9563 Defaults to @samp{()}.
9566 @deftypevr {@code{location-access-controls} parameter} method-access-control-list method-access-controls
9567 Access controls for method-specific access to this path.
9569 Defaults to @samp{()}.
9571 Available @code{method-access-controls} fields are:
9573 @deftypevr {@code{method-access-controls} parameter} boolean reverse?
9574 If @code{#t}, apply access controls to all methods except the listed
9575 methods. Otherwise apply to only the listed methods.
9577 Defaults to @samp{#f}.
9580 @deftypevr {@code{method-access-controls} parameter} method-list methods
9581 Methods to which this access control applies.
9583 Defaults to @samp{()}.
9586 @deftypevr {@code{method-access-controls} parameter} access-control-list access-controls
9587 Access control directives, as a list of strings. Each string should be
9588 one directive, such as "Order allow,deny".
9590 Defaults to @samp{()}.
9595 @deftypevr {@code{cups-configuration} parameter} non-negative-integer log-debug-history
9596 Specifies the number of debugging messages that are retained for logging
9597 if an error occurs in a print job. Debug messages are logged regardless
9598 of the LogLevel setting.
9600 Defaults to @samp{100}.
9603 @deftypevr {@code{cups-configuration} parameter} log-level log-level
9604 Specifies the level of logging for the ErrorLog file. The value
9605 @code{none} stops all logging while @code{debug2} logs everything.
9607 Defaults to @samp{info}.
9610 @deftypevr {@code{cups-configuration} parameter} log-time-format log-time-format
9611 Specifies the format of the date and time in the log files. The value
9612 @code{standard} logs whole seconds while @code{usecs} logs microseconds.
9614 Defaults to @samp{standard}.
9617 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients
9618 Specifies the maximum number of simultaneous clients that are allowed by
9621 Defaults to @samp{100}.
9624 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients-per-host
9625 Specifies the maximum number of simultaneous clients that are allowed
9626 from a single address.
9628 Defaults to @samp{100}.
9631 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-copies
9632 Specifies the maximum number of copies that a user can print of each
9635 Defaults to @samp{9999}.
9638 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-hold-time
9639 Specifies the maximum time a job may remain in the @code{indefinite}
9640 hold state before it is canceled. A value of 0 disables cancellation of
9643 Defaults to @samp{0}.
9646 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs
9647 Specifies the maximum number of simultaneous jobs that are allowed. Set
9648 to 0 to allow an unlimited number of jobs.
9650 Defaults to @samp{500}.
9653 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-printer
9654 Specifies the maximum number of simultaneous jobs that are allowed per
9655 printer. A value of 0 allows up to MaxJobs jobs per printer.
9657 Defaults to @samp{0}.
9660 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-user
9661 Specifies the maximum number of simultaneous jobs that are allowed per
9662 user. A value of 0 allows up to MaxJobs jobs per user.
9664 Defaults to @samp{0}.
9667 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-job-time
9668 Specifies the maximum time a job may take to print before it is
9669 canceled, in seconds. Set to 0 to disable cancellation of "stuck" jobs.
9671 Defaults to @samp{10800}.
9674 @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-log-size
9675 Specifies the maximum size of the log files before they are rotated, in
9676 bytes. The value 0 disables log rotation.
9678 Defaults to @samp{1048576}.
9681 @deftypevr {@code{cups-configuration} parameter} non-negative-integer multiple-operation-timeout
9682 Specifies the maximum amount of time to allow between files in a
9683 multiple file print job, in seconds.
9685 Defaults to @samp{300}.
9688 @deftypevr {@code{cups-configuration} parameter} string page-log-format
9689 Specifies the format of PageLog lines. Sequences beginning with percent
9690 (@samp{%}) characters are replaced with the corresponding information,
9691 while all other characters are copied literally. The following percent
9692 sequences are recognized:
9696 insert a single percent character
9699 insert the value of the specified IPP attribute
9702 insert the number of copies for the current page
9705 insert the current page number
9708 insert the current date and time in common log format
9714 insert the printer name
9720 A value of the empty string disables page logging. The string @code{%p
9721 %u %j %T %P %C %@{job-billing@} %@{job-originating-host-name@}
9722 %@{job-name@} %@{media@} %@{sides@}} creates a page log with the
9725 Defaults to @samp{""}.
9728 @deftypevr {@code{cups-configuration} parameter} environment-variables environment-variables
9729 Passes the specified environment variable(s) to child processes; a list
9732 Defaults to @samp{()}.
9735 @deftypevr {@code{cups-configuration} parameter} policy-configuration-list policies
9736 Specifies named access control policies.
9738 Available @code{policy-configuration} fields are:
9740 @deftypevr {@code{policy-configuration} parameter} string name
9744 @deftypevr {@code{policy-configuration} parameter} string job-private-access
9745 Specifies an access list for a job's private values. @code{@@ACL} maps
9746 to the printer's requesting-user-name-allowed or
9747 requesting-user-name-denied values. @code{@@OWNER} maps to the job's
9748 owner. @code{@@SYSTEM} maps to the groups listed for the
9749 @code{system-group} field of the @code{files-config} configuration,
9750 which is reified into the @code{cups-files.conf(5)} file. Other
9751 possible elements of the access list include specific user names, and
9752 @code{@@@var{group}} to indicate members of a specific group. The
9753 access list may also be simply @code{all} or @code{default}.
9755 Defaults to @samp{"@@OWNER @@SYSTEM"}.
9758 @deftypevr {@code{policy-configuration} parameter} string job-private-values
9759 Specifies the list of job values to make private, or @code{all},
9760 @code{default}, or @code{none}.
9762 Defaults to @samp{"job-name job-originating-host-name
9763 job-originating-user-name phone"}.
9766 @deftypevr {@code{policy-configuration} parameter} string subscription-private-access
9767 Specifies an access list for a subscription's private values.
9768 @code{@@ACL} maps to the printer's requesting-user-name-allowed or
9769 requesting-user-name-denied values. @code{@@OWNER} maps to the job's
9770 owner. @code{@@SYSTEM} maps to the groups listed for the
9771 @code{system-group} field of the @code{files-config} configuration,
9772 which is reified into the @code{cups-files.conf(5)} file. Other
9773 possible elements of the access list include specific user names, and
9774 @code{@@@var{group}} to indicate members of a specific group. The
9775 access list may also be simply @code{all} or @code{default}.
9777 Defaults to @samp{"@@OWNER @@SYSTEM"}.
9780 @deftypevr {@code{policy-configuration} parameter} string subscription-private-values
9781 Specifies the list of job values to make private, or @code{all},
9782 @code{default}, or @code{none}.
9784 Defaults to @samp{"notify-events notify-pull-method notify-recipient-uri
9785 notify-subscriber-user-name notify-user-data"}.
9788 @deftypevr {@code{policy-configuration} parameter} operation-access-control-list access-controls
9789 Access control by IPP operation.
9791 Defaults to @samp{()}.
9795 @deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-files
9796 Specifies whether job files (documents) are preserved after a job is
9797 printed. If a numeric value is specified, job files are preserved for
9798 the indicated number of seconds after printing. Otherwise a boolean
9799 value applies indefinitely.
9801 Defaults to @samp{86400}.
9804 @deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-history
9805 Specifies whether the job history is preserved after a job is printed.
9806 If a numeric value is specified, the job history is preserved for the
9807 indicated number of seconds after printing. If @code{#t}, the job
9808 history is preserved until the MaxJobs limit is reached.
9810 Defaults to @samp{#t}.
9813 @deftypevr {@code{cups-configuration} parameter} non-negative-integer reload-timeout
9814 Specifies the amount of time to wait for job completion before
9815 restarting the scheduler.
9817 Defaults to @samp{30}.
9820 @deftypevr {@code{cups-configuration} parameter} string rip-cache
9821 Specifies the maximum amount of memory to use when converting documents
9822 into bitmaps for a printer.
9824 Defaults to @samp{"128m"}.
9827 @deftypevr {@code{cups-configuration} parameter} string server-admin
9828 Specifies the email address of the server administrator.
9830 Defaults to @samp{"root@@localhost.localdomain"}.
9833 @deftypevr {@code{cups-configuration} parameter} host-name-list-or-* server-alias
9834 The ServerAlias directive is used for HTTP Host header validation when
9835 clients connect to the scheduler from external interfaces. Using the
9836 special name @code{*} can expose your system to known browser-based DNS
9837 rebinding attacks, even when accessing sites through a firewall. If the
9838 auto-discovery of alternate names does not work, we recommend listing
9839 each alternate name with a ServerAlias directive instead of using
9842 Defaults to @samp{*}.
9845 @deftypevr {@code{cups-configuration} parameter} string server-name
9846 Specifies the fully-qualified host name of the server.
9848 Defaults to @samp{"localhost"}.
9851 @deftypevr {@code{cups-configuration} parameter} server-tokens server-tokens
9852 Specifies what information is included in the Server header of HTTP
9853 responses. @code{None} disables the Server header. @code{ProductOnly}
9854 reports @code{CUPS}. @code{Major} reports @code{CUPS 2}. @code{Minor}
9855 reports @code{CUPS 2.0}. @code{Minimal} reports @code{CUPS 2.0.0}.
9856 @code{OS} reports @code{CUPS 2.0.0 (@var{uname})} where @var{uname} is
9857 the output of the @code{uname} command. @code{Full} reports @code{CUPS
9858 2.0.0 (@var{uname}) IPP/2.0}.
9860 Defaults to @samp{Minimal}.
9863 @deftypevr {@code{cups-configuration} parameter} string set-env
9864 Set the specified environment variable to be passed to child processes.
9866 Defaults to @samp{"variable value"}.
9869 @deftypevr {@code{cups-configuration} parameter} multiline-string-list ssl-listen
9870 Listens on the specified interfaces for encrypted connections. Valid
9871 values are of the form @var{address}:@var{port}, where @var{address} is
9872 either an IPv6 address enclosed in brackets, an IPv4 address, or
9873 @code{*} to indicate all addresses.
9875 Defaults to @samp{()}.
9878 @deftypevr {@code{cups-configuration} parameter} ssl-options ssl-options
9879 Sets encryption options. By default, CUPS only supports encryption
9880 using TLS v1.0 or higher using known secure cipher suites. The
9881 @code{AllowRC4} option enables the 128-bit RC4 cipher suites, which are
9882 required for some older clients that do not implement newer ones. The
9883 @code{AllowSSL3} option enables SSL v3.0, which is required for some
9884 older clients that do not support TLS v1.0.
9886 Defaults to @samp{()}.
9889 @deftypevr {@code{cups-configuration} parameter} boolean strict-conformance?
9890 Specifies whether the scheduler requires clients to strictly adhere to
9891 the IPP specifications.
9893 Defaults to @samp{#f}.
9896 @deftypevr {@code{cups-configuration} parameter} non-negative-integer timeout
9897 Specifies the HTTP request timeout, in seconds.
9899 Defaults to @samp{300}.
9903 @deftypevr {@code{cups-configuration} parameter} boolean web-interface?
9904 Specifies whether the web interface is enabled.
9906 Defaults to @samp{#f}.
9909 At this point you're probably thinking ``oh dear, Guix manual, I like
9910 you but you can stop already with the configuration options''. Indeed.
9911 However, one more point: it could be that you have an existing
9912 @code{cupsd.conf} that you want to use. In that case, you can pass an
9913 @code{opaque-cups-configuration} as the configuration of a
9914 @code{cups-service-type}.
9916 Available @code{opaque-cups-configuration} fields are:
9918 @deftypevr {@code{opaque-cups-configuration} parameter} package cups
9922 @deftypevr {@code{opaque-cups-configuration} parameter} string cupsd.conf
9923 The contents of the @code{cupsd.conf}, as a string.
9926 @deftypevr {@code{opaque-cups-configuration} parameter} string cups-files.conf
9927 The contents of the @code{cups-files.conf} file, as a string.
9930 For example, if your @code{cupsd.conf} and @code{cups-files.conf} are in
9931 strings of the same name, you could instantiate a CUPS service like
9935 (service cups-service-type
9936 (opaque-cups-configuration
9937 (cupsd.conf cupsd.conf)
9938 (cups-files.conf cups-files.conf)))
9942 @node Desktop Services
9943 @subsubsection Desktop Services
9945 The @code{(gnu services desktop)} module provides services that are
9946 usually useful in the context of a ``desktop'' setup---that is, on a
9947 machine running a graphical display server, possibly with graphical user
9948 interfaces, etc. It also defines services that provide specific desktop
9949 environments like GNOME and XFCE.
9951 To simplify things, the module defines a variable containing the set of
9952 services that users typically expect on a machine with a graphical
9953 environment and networking:
9955 @defvr {Scheme Variable} %desktop-services
9956 This is a list of services that builds upon @var{%base-services} and
9957 adds or adjusts services for a typical ``desktop'' setup.
9959 In particular, it adds a graphical login manager (@pxref{X Window,
9960 @code{slim-service}}), screen lockers,
9961 a network management tool (@pxref{Networking
9962 Services, @code{wicd-service}}), energy and color management services,
9963 the @code{elogind} login and seat manager, the Polkit privilege service,
9964 the GeoClue location service, an NTP client (@pxref{Networking
9965 Services}), the Avahi daemon, and has the name service switch service
9966 configured to be able to use @code{nss-mdns} (@pxref{Name Service
9970 The @var{%desktop-services} variable can be used as the @code{services}
9971 field of an @code{operating-system} declaration (@pxref{operating-system
9972 Reference, @code{services}}).
9974 Additionally, the @code{gnome-desktop-service} and
9975 @code{xfce-desktop-service} procedures can add GNOME and/or XFCE to a
9976 system. To ``add GNOME'' means that system-level services like the
9977 backlight adjustment helpers and the power management utilities are
9978 added to the system, extending @code{polkit} and @code{dbus}
9979 appropriately, allowing GNOME to operate with elevated privileges on a
9980 limited number of special-purpose system interfaces. Additionally,
9981 adding a service made by @code{gnome-desktop-service} adds the GNOME
9982 metapackage to the system profile. Likewise, adding the XFCE service
9983 not only adds the @code{xfce} metapackage to the system profile, but it
9984 also gives the Thunar file manager the ability to open a ``root-mode''
9985 file management window, if the user authenticates using the
9986 administrator's password via the standard polkit graphical interface.
9988 @deffn {Scheme Procedure} gnome-desktop-service
9989 Return a service that adds the @code{gnome} package to the system
9990 profile, and extends polkit with the actions from
9991 @code{gnome-settings-daemon}.
9994 @deffn {Scheme Procedure} xfce-desktop-service
9995 Return a service that adds the @code{xfce} package to the system profile,
9996 and extends polkit with the ability for @code{thunar} to manipulate the
9997 file system as root from within a user session, after the user has
9998 authenticated with the administrator's password.
10001 Because the GNOME and XFCE desktop services pull in so many packages,
10002 the default @code{%desktop-services} variable doesn't include either of
10003 them by default. To add GNOME or XFCE, just @code{cons} them onto
10004 @code{%desktop-services} in the @code{services} field of your
10005 @code{operating-system}:
10008 (use-modules (gnu))
10009 (use-service-modules desktop)
10012 ;; cons* adds items to the list given as its last argument.
10013 (services (cons* (gnome-desktop-service)
10014 (xfce-desktop-service)
10015 %desktop-services))
10019 These desktop environments will then be available as options in the
10020 graphical login window.
10022 The actual service definitions included in @code{%desktop-services} and
10023 provided by @code{(gnu services dbus)} and @code{(gnu services desktop)}
10024 are described below.
10026 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
10027 Return a service that runs the ``system bus'', using @var{dbus}, with
10028 support for @var{services}.
10030 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
10031 facility. Its system bus is used to allow system services to communicate
10032 and to be notified of system-wide events.
10034 @var{services} must be a list of packages that provide an
10035 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
10036 and policy files. For example, to allow avahi-daemon to use the system bus,
10037 @var{services} must be equal to @code{(list avahi)}.
10040 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
10041 Return a service that runs the @code{elogind} login and
10042 seat management daemon. @uref{https://github.com/andywingo/elogind,
10043 Elogind} exposes a D-Bus interface that can be used to know which users
10044 are logged in, know what kind of sessions they have open, suspend the
10045 system, inhibit system suspend, reboot the system, and other tasks.
10047 Elogind handles most system-level power events for a computer, for
10048 example suspending the system when a lid is closed, or shutting it down
10049 when the power button is pressed.
10051 The @var{config} keyword argument specifies the configuration for
10052 elogind, and should be the result of an @code{(elogind-configuration
10053 (@var{parameter} @var{value})...)} invocation. Available parameters and
10054 their default values are:
10057 @item kill-user-processes?
10059 @item kill-only-users
10061 @item kill-exclude-users
10063 @item inhibit-delay-max-seconds
10065 @item handle-power-key
10067 @item handle-suspend-key
10069 @item handle-hibernate-key
10071 @item handle-lid-switch
10073 @item handle-lid-switch-docked
10075 @item power-key-ignore-inhibited?
10077 @item suspend-key-ignore-inhibited?
10079 @item hibernate-key-ignore-inhibited?
10081 @item lid-switch-ignore-inhibited?
10083 @item holdoff-timeout-seconds
10087 @item idle-action-seconds
10089 @item runtime-directory-size-percent
10091 @item runtime-directory-size
10095 @item suspend-state
10096 @code{("mem" "standby" "freeze")}
10099 @item hibernate-state
10101 @item hibernate-mode
10102 @code{("platform" "shutdown")}
10103 @item hybrid-sleep-state
10105 @item hybrid-sleep-mode
10106 @code{("suspend" "platform" "shutdown")}
10110 @deffn {Scheme Procedure} polkit-service @
10111 [#:polkit @var{polkit}]
10112 Return a service that runs the
10113 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
10114 management service}, which allows system administrators to grant access to
10115 privileged operations in a structured way. By querying the Polkit service, a
10116 privileged system component can know when it should grant additional
10117 capabilities to ordinary users. For example, an ordinary user can be granted
10118 the capability to suspend the system if the user is logged in locally.
10121 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
10122 [#:watts-up-pro? #f] @
10123 [#:poll-batteries? #t] @
10124 [#:ignore-lid? #f] @
10125 [#:use-percentage-for-policy? #f] @
10126 [#:percentage-low 10] @
10127 [#:percentage-critical 3] @
10128 [#:percentage-action 2] @
10129 [#:time-low 1200] @
10130 [#:time-critical 300] @
10131 [#:time-action 120] @
10132 [#:critical-power-action 'hybrid-sleep]
10133 Return a service that runs @uref{http://upower.freedesktop.org/,
10134 @command{upowerd}}, a system-wide monitor for power consumption and battery
10135 levels, with the given configuration settings. It implements the
10136 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
10140 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
10141 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
10142 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
10143 notifications and ways to mount/unmount disks. Programs that talk to UDisks
10144 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
10147 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
10148 Return a service that runs @command{colord}, a system service with a D-Bus
10149 interface to manage the color profiles of input and output devices such as
10150 screens and scanners. It is notably used by the GNOME Color Manager graphical
10151 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
10152 site} for more information.
10155 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
10156 Return a configuration allowing an application to access GeoClue
10157 location data. @var{name} is the Desktop ID of the application, without
10158 the @code{.desktop} part. If @var{allowed?} is true, the application
10159 will have access to location information by default. The boolean
10160 @var{system?} value indicates whether an application is a system component
10161 or not. Finally @var{users} is a list of UIDs of all users for which
10162 this application is allowed location info access. An empty users list
10163 means that all users are allowed.
10166 @defvr {Scheme Variable} %standard-geoclue-applications
10167 The standard list of well-known GeoClue application configurations,
10168 granting authority to the GNOME date-and-time utility to ask for the
10169 current location in order to set the time zone, and allowing the
10170 IceCat and Epiphany web browsers to request location information.
10171 IceCat and Epiphany both query the user before allowing a web page to
10172 know the user's location.
10175 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
10176 [#:whitelist '()] @
10177 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
10178 [#:submit-data? #f]
10179 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
10180 [#:submission-nick "geoclue"] @
10181 [#:applications %standard-geoclue-applications]
10182 Return a service that runs the GeoClue location service. This service
10183 provides a D-Bus interface to allow applications to request access to a
10184 user's physical location, and optionally to add information to online
10185 location databases. See
10186 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
10187 web site} for more information.
10190 @deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}]
10191 Return a service that runs the @command{bluetoothd} daemon, which manages
10192 all the Bluetooth devices and provides a number of D-Bus interfaces.
10194 Users need to be in the @code{lp} group to access the D-Bus service.
10197 @node Database Services
10198 @subsubsection Database Services
10202 The @code{(gnu services databases)} module provides the following services.
10204 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
10205 [#:config-file] [#:data-directory ``/var/lib/postgresql/data''] @
10206 [#:port 5432] [#:locale ``en_US.utf8'']
10207 Return a service that runs @var{postgresql}, the PostgreSQL database
10210 The PostgreSQL daemon loads its runtime configuration from @var{config-file},
10211 creates a database cluster with @var{locale} as the default
10212 locale, stored in @var{data-directory}. It then listens on @var{port}.
10215 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
10216 Return a service that runs @command{mysqld}, the MySQL or MariaDB
10219 The optional @var{config} argument specifies the configuration for
10220 @command{mysqld}, which should be a @code{<mysql-configuration>} object.
10223 @deftp {Data Type} mysql-configuration
10224 Data type representing the configuration of @var{mysql-service}.
10227 @item @code{mysql} (default: @var{mariadb})
10228 Package object of the MySQL database server, can be either @var{mariadb}
10231 For MySQL, a temporary root password will be displayed at activation time.
10232 For MariaDB, the root password is empty.
10234 @item @code{port} (default: @code{3306})
10235 TCP port on which the database server listens for incoming connections.
10239 @node Mail Services
10240 @subsubsection Mail Services
10244 The @code{(gnu services mail)} module provides Guix service definitions
10245 for email services: IMAP, POP3, and LMTP servers, as well as mail
10246 transport agents (MTAs). Lots of acronyms! These services are detailed
10247 in the subsections below.
10249 @subsubheading Dovecot Service
10251 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
10252 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
10255 By default, Dovecot does not need much configuration; the default
10256 configuration object created by @code{(dovecot-configuration)} will
10257 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
10258 certificate will be generated for TLS-protected connections, though
10259 Dovecot will also listen on cleartext ports by default. There are a
10260 number of options, though, which mail administrators might need to change,
10261 and as is the case with other services, Guix allows the system
10262 administrator to specify these parameters via a uniform Scheme interface.
10264 For example, to specify that mail is located at @code{maildir~/.mail},
10265 one would instantiate the Dovecot service like this:
10268 (dovecot-service #:config
10269 (dovecot-configuration
10270 (mail-location "maildir:~/.mail")))
10273 The available configuration parameters follow. Each parameter
10274 definition is preceded by its type; for example, @samp{string-list foo}
10275 indicates that the @code{foo} parameter should be specified as a list of
10276 strings. There is also a way to specify the configuration as a string,
10277 if you have an old @code{dovecot.conf} file that you want to port over
10278 from some other system; see the end for more details.
10280 @c The following documentation was initially generated by
10281 @c (generate-documentation) in (gnu services mail). Manually maintained
10282 @c documentation is better, so we shouldn't hesitate to edit below as
10283 @c needed. However if the change you want to make to this documentation
10284 @c can be done in an automated way, it's probably easier to change
10285 @c (generate-documentation) than to make it below and have to deal with
10286 @c the churn as dovecot updates.
10288 Available @code{dovecot-configuration} fields are:
10290 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
10291 The dovecot package.
10294 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
10295 A list of IPs or hosts where to listen for connections. @samp{*}
10296 listens on all IPv4 interfaces, @samp{::} listens on all IPv6
10297 interfaces. If you want to specify non-default ports or anything more
10298 complex, customize the address and port fields of the
10299 @samp{inet-listener} of the specific services you are interested in.
10302 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
10303 List of protocols we want to serve. Available protocols include
10304 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
10306 Available @code{protocol-configuration} fields are:
10308 @deftypevr {@code{protocol-configuration} parameter} string name
10309 The name of the protocol.
10312 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
10313 UNIX socket path to the master authentication server to find users.
10314 This is used by imap (for shared users) and lda.
10315 It defaults to @samp{"/var/run/dovecot/auth-userdb"}.
10318 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
10319 Space separated list of plugins to load.
10322 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
10323 Maximum number of IMAP connections allowed for a user from each IP
10324 address. NOTE: The username is compared case-sensitively.
10325 Defaults to @samp{10}.
10330 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
10331 List of services to enable. Available services include @samp{imap},
10332 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
10335 Available @code{service-configuration} fields are:
10337 @deftypevr {@code{service-configuration} parameter} string kind
10338 The service kind. Valid values include @code{director},
10339 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
10340 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
10341 @code{tcpwrap}, @code{quota-warning}, or anything else.
10344 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
10345 Listeners for the service. A listener is either a
10346 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
10347 an @code{inet-listener-configuration}.
10348 Defaults to @samp{()}.
10350 Available @code{unix-listener-configuration} fields are:
10352 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
10353 The file name on which to listen.
10356 @deftypevr {@code{unix-listener-configuration} parameter} string mode
10357 The access mode for the socket.
10358 Defaults to @samp{"0600"}.
10361 @deftypevr {@code{unix-listener-configuration} parameter} string user
10362 The user to own the socket.
10363 Defaults to @samp{""}.
10366 @deftypevr {@code{unix-listener-configuration} parameter} string group
10367 The group to own the socket.
10368 Defaults to @samp{""}.
10372 Available @code{fifo-listener-configuration} fields are:
10374 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
10375 The file name on which to listen.
10378 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
10379 The access mode for the socket.
10380 Defaults to @samp{"0600"}.
10383 @deftypevr {@code{fifo-listener-configuration} parameter} string user
10384 The user to own the socket.
10385 Defaults to @samp{""}.
10388 @deftypevr {@code{fifo-listener-configuration} parameter} string group
10389 The group to own the socket.
10390 Defaults to @samp{""}.
10394 Available @code{inet-listener-configuration} fields are:
10396 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
10397 The protocol to listen for.
10400 @deftypevr {@code{inet-listener-configuration} parameter} string address
10401 The address on which to listen, or empty for all addresses.
10402 Defaults to @samp{""}.
10405 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
10406 The port on which to listen.
10409 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
10410 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
10412 Defaults to @samp{#t}.
10417 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
10418 Number of connections to handle before starting a new process.
10419 Typically the only useful values are 0 (unlimited) or 1. 1 is more
10420 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
10421 Defaults to @samp{1}.
10424 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
10425 Number of processes to always keep waiting for more connections.
10426 Defaults to @samp{0}.
10429 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
10430 If you set @samp{service-count 0}, you probably need to grow
10432 Defaults to @samp{256000000}.
10437 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
10438 Dict configuration, as created by the @code{dict-configuration}
10441 Available @code{dict-configuration} fields are:
10443 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
10444 A list of key-value pairs that this dict should hold.
10445 Defaults to @samp{()}.
10450 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
10451 A list of passdb configurations, each one created by the
10452 @code{passdb-configuration} constructor.
10454 Available @code{passdb-configuration} fields are:
10456 @deftypevr {@code{passdb-configuration} parameter} string driver
10457 The driver that the passdb should use. Valid values include
10458 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
10460 Defaults to @samp{"pam"}.
10463 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
10464 A list of key-value args to the passdb driver.
10465 Defaults to @samp{()}.
10470 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
10471 List of userdb configurations, each one created by the
10472 @code{userdb-configuration} constructor.
10474 Available @code{userdb-configuration} fields are:
10476 @deftypevr {@code{userdb-configuration} parameter} string driver
10477 The driver that the userdb should use. Valid values include
10478 @samp{passwd} and @samp{static}.
10479 Defaults to @samp{"passwd"}.
10482 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
10483 A list of key-value args to the userdb driver.
10484 Defaults to @samp{()}.
10487 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
10488 Override fields from passwd.
10489 Defaults to @samp{()}.
10494 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
10495 Plug-in configuration, created by the @code{plugin-configuration}
10499 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
10500 List of namespaces. Each item in the list is created by the
10501 @code{namespace-configuration} constructor.
10503 Available @code{namespace-configuration} fields are:
10505 @deftypevr {@code{namespace-configuration} parameter} string name
10506 Name for this namespace.
10509 @deftypevr {@code{namespace-configuration} parameter} string type
10510 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
10511 Defaults to @samp{"private"}.
10514 @deftypevr {@code{namespace-configuration} parameter} string separator
10515 Hierarchy separator to use. You should use the same separator for
10516 all namespaces or some clients get confused. @samp{/} is usually a good
10517 one. The default however depends on the underlying mail storage
10519 Defaults to @samp{""}.
10522 @deftypevr {@code{namespace-configuration} parameter} string prefix
10523 Prefix required to access this namespace. This needs to be
10524 different for all namespaces. For example @samp{Public/}.
10525 Defaults to @samp{""}.
10528 @deftypevr {@code{namespace-configuration} parameter} string location
10529 Physical location of the mailbox. This is in the same format as
10530 mail_location, which is also the default for it.
10531 Defaults to @samp{""}.
10534 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
10535 There can be only one INBOX, and this setting defines which
10537 Defaults to @samp{#f}.
10540 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
10541 If namespace is hidden, it's not advertised to clients via NAMESPACE
10542 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
10543 useful when converting from another server with different namespaces
10544 which you want to deprecate but still keep working. For example you can
10545 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
10547 Defaults to @samp{#f}.
10550 @deftypevr {@code{namespace-configuration} parameter} boolean list?
10551 Show the mailboxes under this namespace with the LIST command. This
10552 makes the namespace visible for clients that do not support the NAMESPACE
10553 extension. The special @code{children} value lists child mailboxes, but
10554 hides the namespace prefix.
10555 Defaults to @samp{#t}.
10558 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
10559 Namespace handles its own subscriptions. If set to @code{#f}, the
10560 parent namespace handles them. The empty prefix should always have this
10562 Defaults to @samp{#t}.
10565 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
10566 List of predefined mailboxes in this namespace.
10567 Defaults to @samp{()}.
10569 Available @code{mailbox-configuration} fields are:
10571 @deftypevr {@code{mailbox-configuration} parameter} string name
10572 Name for this mailbox.
10575 @deftypevr {@code{mailbox-configuration} parameter} string auto
10576 @samp{create} will automatically create this mailbox.
10577 @samp{subscribe} will both create and subscribe to the mailbox.
10578 Defaults to @samp{"no"}.
10581 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
10582 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
10583 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
10584 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
10585 Defaults to @samp{()}.
10592 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
10593 Base directory where to store runtime data.
10594 Defaults to @samp{"/var/run/dovecot/"}.
10597 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
10598 Greeting message for clients.
10599 Defaults to @samp{"Dovecot ready."}.
10602 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
10603 List of trusted network ranges. Connections from these IPs are
10604 allowed to override their IP addresses and ports (for logging and for
10605 authentication checks). @samp{disable-plaintext-auth} is also ignored
10606 for these networks. Typically you would specify your IMAP proxy servers
10608 Defaults to @samp{()}.
10611 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
10612 List of login access check sockets (e.g. tcpwrap).
10613 Defaults to @samp{()}.
10616 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
10617 Show more verbose process titles (in ps). Currently shows user name
10618 and IP address. Useful for seeing who is actually using the IMAP
10619 processes (e.g. shared mailboxes or if the same uid is used for multiple
10621 Defaults to @samp{#f}.
10624 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
10625 Should all processes be killed when Dovecot master process shuts down.
10626 Setting this to @code{#f} means that Dovecot can be upgraded without
10627 forcing existing client connections to close (although that could also
10628 be a problem if the upgrade is e.g. due to a security fix).
10629 Defaults to @samp{#t}.
10632 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
10633 If non-zero, run mail commands via this many connections to doveadm
10634 server, instead of running them directly in the same process.
10635 Defaults to @samp{0}.
10638 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
10639 UNIX socket or host:port used for connecting to doveadm server.
10640 Defaults to @samp{"doveadm-server"}.
10643 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
10644 List of environment variables that are preserved on Dovecot startup
10645 and passed down to all of its child processes. You can also give
10646 key=value pairs to always set specific settings.
10649 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
10650 Disable LOGIN command and all other plaintext authentications unless
10651 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
10652 matches the local IP (i.e. you're connecting from the same computer),
10653 the connection is considered secure and plaintext authentication is
10654 allowed. See also ssl=required setting.
10655 Defaults to @samp{#t}.
10658 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
10659 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
10660 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
10661 for caching to be used.
10662 Defaults to @samp{0}.
10665 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
10666 Time to live for cached data. After TTL expires the cached record
10667 is no longer used, *except* if the main database lookup returns internal
10668 failure. We also try to handle password changes automatically: If
10669 user's previous authentication was successful, but this one wasn't, the
10670 cache isn't used. For now this works only with plaintext
10672 Defaults to @samp{"1 hour"}.
10675 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
10676 TTL for negative hits (user not found, password mismatch).
10677 0 disables caching them completely.
10678 Defaults to @samp{"1 hour"}.
10681 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
10682 List of realms for SASL authentication mechanisms that need them.
10683 You can leave it empty if you don't want to support multiple realms.
10684 Many clients simply use the first one listed here, so keep the default
10686 Defaults to @samp{()}.
10689 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
10690 Default realm/domain to use if none was specified. This is used for
10691 both SASL realms and appending @@domain to username in plaintext
10693 Defaults to @samp{""}.
10696 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
10697 List of allowed characters in username. If the user-given username
10698 contains a character not listed in here, the login automatically fails.
10699 This is just an extra check to make sure user can't exploit any
10700 potential quote escaping vulnerabilities with SQL/LDAP databases. If
10701 you want to allow all characters, set this value to empty.
10702 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
10705 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
10706 Username character translations before it's looked up from
10707 databases. The value contains series of from -> to characters. For
10708 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
10709 translated to @samp{@@}.
10710 Defaults to @samp{""}.
10713 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
10714 Username formatting before it's looked up from databases. You can
10715 use the standard variables here, e.g. %Lu would lowercase the username,
10716 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
10717 change the @samp{@@} into @samp{-AT-}. This translation is done after
10718 @samp{auth-username-translation} changes.
10719 Defaults to @samp{"%Lu"}.
10722 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
10723 If you want to allow master users to log in by specifying the master
10724 username within the normal username string (i.e. not using SASL
10725 mechanism's support for it), you can specify the separator character
10726 here. The format is then <username><separator><master username>.
10727 UW-IMAP uses @samp{*} as the separator, so that could be a good
10729 Defaults to @samp{""}.
10732 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
10733 Username to use for users logging in with ANONYMOUS SASL
10735 Defaults to @samp{"anonymous"}.
10738 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
10739 Maximum number of dovecot-auth worker processes. They're used to
10740 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
10741 They're automatically created and destroyed as needed.
10742 Defaults to @samp{30}.
10745 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
10746 Host name to use in GSSAPI principal names. The default is to use
10747 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
10748 allow all keytab entries.
10749 Defaults to @samp{""}.
10752 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
10753 Kerberos keytab to use for the GSSAPI mechanism. Will use the
10754 system default (usually @file{/etc/krb5.keytab}) if not specified. You may
10755 need to change the auth service to run as root to be able to read this
10757 Defaults to @samp{""}.
10760 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
10761 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
10762 and @samp{ntlm-auth} helper.
10763 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
10764 Defaults to @samp{#f}.
10767 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
10768 Path for Samba's @samp{ntlm-auth} helper binary.
10769 Defaults to @samp{"/usr/bin/ntlm_auth"}.
10772 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
10773 Time to delay before replying to failed authentications.
10774 Defaults to @samp{"2 secs"}.
10777 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
10778 Require a valid SSL client certificate or the authentication
10780 Defaults to @samp{#f}.
10783 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
10784 Take the username from client's SSL certificate, using
10785 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
10787 Defaults to @samp{#f}.
10790 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
10791 List of wanted authentication mechanisms. Supported mechanisms are:
10792 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
10793 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
10794 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
10795 @samp{disable-plaintext-auth} setting.
10798 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
10799 List of IPs or hostnames to all director servers, including ourself.
10800 Ports can be specified as ip:port. The default port is the same as what
10801 director service's @samp{inet-listener} is using.
10802 Defaults to @samp{()}.
10805 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
10806 List of IPs or hostnames to all backend mail servers. Ranges are
10807 allowed too, like 10.0.0.10-10.0.0.30.
10808 Defaults to @samp{()}.
10811 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
10812 How long to redirect users to a specific server after it no longer
10813 has any connections.
10814 Defaults to @samp{"15 min"}.
10817 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
10818 TCP/IP port that accepts doveadm connections (instead of director
10819 connections) If you enable this, you'll also need to add
10820 @samp{inet-listener} for the port.
10821 Defaults to @samp{0}.
10824 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
10825 How the username is translated before being hashed. Useful values
10826 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
10827 are shared within domain.
10828 Defaults to @samp{"%Lu"}.
10831 @deftypevr {@code{dovecot-configuration} parameter} string log-path
10832 Log file to use for error messages. @samp{syslog} logs to syslog,
10833 @samp{/dev/stderr} logs to stderr.
10834 Defaults to @samp{"syslog"}.
10837 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
10838 Log file to use for informational messages. Defaults to
10840 Defaults to @samp{""}.
10843 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
10844 Log file to use for debug messages. Defaults to
10845 @samp{info-log-path}.
10846 Defaults to @samp{""}.
10849 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
10850 Syslog facility to use if you're logging to syslog. Usually if you
10851 don't want to use @samp{mail}, you'll use local0..local7. Also other
10852 standard facilities are supported.
10853 Defaults to @samp{"mail"}.
10856 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
10857 Log unsuccessful authentication attempts and the reasons why they
10859 Defaults to @samp{#f}.
10862 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
10863 In case of password mismatches, log the attempted password. Valid
10864 values are no, plain and sha1. sha1 can be useful for detecting brute
10865 force password attempts vs. user simply trying the same password over
10866 and over again. You can also truncate the value to n chars by appending
10867 ":n" (e.g. sha1:6).
10868 Defaults to @samp{#f}.
10871 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
10872 Even more verbose logging for debugging purposes. Shows for example
10874 Defaults to @samp{#f}.
10877 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
10878 In case of password mismatches, log the passwords and used scheme so
10879 the problem can be debugged. Enabling this also enables
10881 Defaults to @samp{#f}.
10884 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
10885 Enable mail process debugging. This can help you figure out why
10886 Dovecot isn't finding your mails.
10887 Defaults to @samp{#f}.
10890 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
10891 Show protocol level SSL errors.
10892 Defaults to @samp{#f}.
10895 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
10896 Prefix for each line written to log file. % codes are in
10897 strftime(3) format.
10898 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
10901 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
10902 List of elements we want to log. The elements which have a
10903 non-empty variable value are joined together to form a comma-separated
10907 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
10908 Login log format. %s contains @samp{login-log-format-elements}
10909 string, %$ contains the data we want to log.
10910 Defaults to @samp{"%$: %s"}.
10913 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
10914 Log prefix for mail processes. See doc/wiki/Variables.txt for list
10915 of possible variables you can use.
10916 Defaults to @samp{"\"%s(%u): \""}.
10919 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
10920 Format to use for logging mail deliveries. You can use variables:
10923 Delivery status message (e.g. @samp{saved to INBOX})
10935 Defaults to @samp{"msgid=%m: %$"}.
10938 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
10939 Location for users' mailboxes. The default is empty, which means
10940 that Dovecot tries to find the mailboxes automatically. This won't work
10941 if the user doesn't yet have any mail, so you should explicitly tell
10942 Dovecot the full location.
10944 If you're using mbox, giving a path to the INBOX
10945 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
10946 where the other mailboxes are kept. This is called the "root mail
10947 directory", and it must be the first path given in the
10948 @samp{mail-location} setting.
10950 There are a few special variables you can use, eg.:
10956 user part in user@@domain, same as %u if there's no domain
10958 domain part in user@@domain, empty if there's no domain
10963 See doc/wiki/Variables.txt for full list. Some examples:
10965 @item maildir:~/Maildir
10966 @item mbox:~/mail:INBOX=/var/mail/%u
10967 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
10969 Defaults to @samp{""}.
10972 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
10973 System user and group used to access mails. If you use multiple,
10974 userdb can override these by returning uid or gid fields. You can use
10975 either numbers or names. <doc/wiki/UserIds.txt>.
10976 Defaults to @samp{""}.
10979 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
10981 Defaults to @samp{""}.
10984 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
10985 Group to enable temporarily for privileged operations. Currently
10986 this is used only with INBOX when either its initial creation or
10987 dotlocking fails. Typically this is set to "mail" to give access to
10989 Defaults to @samp{""}.
10992 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
10993 Grant access to these supplementary groups for mail processes.
10994 Typically these are used to set up access to shared mailboxes. Note
10995 that it may be dangerous to set these if users can create
10996 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
10997 could allow a user to delete others' mailboxes, or ln -s
10998 /secret/shared/box ~/mail/mybox would allow reading it).
10999 Defaults to @samp{""}.
11002 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
11003 Allow full file system access to clients. There's no access checks
11004 other than what the operating system does for the active UID/GID. It
11005 works with both maildir and mboxes, allowing you to prefix mailboxes
11006 names with e.g. /path/ or ~user/.
11007 Defaults to @samp{#f}.
11010 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
11011 Don't use mmap() at all. This is required if you store indexes to
11012 shared file systems (NFS or clustered file system).
11013 Defaults to @samp{#f}.
11016 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
11017 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
11018 supports @samp{O_EXCL} since version 3, so this should be safe to use
11019 nowadays by default.
11020 Defaults to @samp{#t}.
11023 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
11024 When to use fsync() or fdatasync() calls:
11027 Whenever necessary to avoid losing important data
11029 Useful with e.g. NFS when write()s are delayed
11031 Never use it (best performance, but crashes can lose data).
11033 Defaults to @samp{"optimized"}.
11036 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
11037 Mail storage exists in NFS. Set this to yes to make Dovecot flush
11038 NFS caches whenever needed. If you're using only a single mail server
11040 Defaults to @samp{#f}.
11043 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
11044 Mail index files also exist in NFS. Setting this to yes requires
11045 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
11046 Defaults to @samp{#f}.
11049 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
11050 Locking method for index files. Alternatives are fcntl, flock and
11051 dotlock. Dotlocking uses some tricks which may create more disk I/O
11052 than other locking methods. NFS users: flock doesn't work, remember to
11053 change @samp{mmap-disable}.
11054 Defaults to @samp{"fcntl"}.
11057 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
11058 Directory in which LDA/LMTP temporarily stores incoming mails >128
11060 Defaults to @samp{"/tmp"}.
11063 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
11064 Valid UID range for users. This is mostly to make sure that users can't
11065 log in as daemons or other system users. Note that denying root logins is
11066 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
11068 Defaults to @samp{500}.
11071 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
11073 Defaults to @samp{0}.
11076 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
11077 Valid GID range for users. Users having non-valid GID as primary group ID
11078 aren't allowed to log in. If user belongs to supplementary groups with
11079 non-valid GIDs, those groups are not set.
11080 Defaults to @samp{1}.
11083 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
11085 Defaults to @samp{0}.
11088 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
11089 Maximum allowed length for mail keyword name. It's only forced when
11090 trying to create new keywords.
11091 Defaults to @samp{50}.
11094 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
11095 List of directories under which chrooting is allowed for mail
11096 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
11097 too). This setting doesn't affect @samp{login-chroot}
11098 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
11099 "/./" in home dirs are ignored. WARNING: Never add directories here
11100 which local users can modify, that may lead to root exploit. Usually
11101 this should be done only if you don't allow shell access for users.
11102 <doc/wiki/Chrooting.txt>.
11103 Defaults to @samp{()}.
11106 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
11107 Default chroot directory for mail processes. This can be overridden
11108 for specific users in user database by giving /./ in user's home
11109 directory (e.g. /home/./user chroots into /home). Note that usually
11110 there is no real need to do chrooting, Dovecot doesn't allow users to
11111 access files outside their mail directory anyway. If your home
11112 directories are prefixed with the chroot directory, append "/." to
11113 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
11114 Defaults to @samp{""}.
11117 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
11118 UNIX socket path to master authentication server to find users.
11119 This is used by imap (for shared users) and lda.
11120 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
11123 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
11124 Directory where to look up mail plugins.
11125 Defaults to @samp{"/usr/lib/dovecot"}.
11128 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
11129 List of plugins to load for all services. Plugins specific to IMAP,
11130 LDA, etc. are added to this list in their own .conf files.
11131 Defaults to @samp{()}.
11134 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
11135 The minimum number of mails in a mailbox before updates are done to
11136 cache file. This allows optimizing Dovecot's behavior to do less disk
11137 writes at the cost of more disk reads.
11138 Defaults to @samp{0}.
11141 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
11142 When IDLE command is running, mailbox is checked once in a while to
11143 see if there are any new mails or other changes. This setting defines
11144 the minimum time to wait between those checks. Dovecot can also use
11145 dnotify, inotify and kqueue to find out immediately when changes
11147 Defaults to @samp{"30 secs"}.
11150 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
11151 Save mails with CR+LF instead of plain LF. This makes sending those
11152 mails take less CPU, especially with sendfile() syscall with Linux and
11153 FreeBSD. But it also creates a bit more disk I/O which may just make it
11154 slower. Also note that if other software reads the mboxes/maildirs,
11155 they may handle the extra CRs wrong and cause problems.
11156 Defaults to @samp{#f}.
11159 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
11160 By default LIST command returns all entries in maildir beginning
11161 with a dot. Enabling this option makes Dovecot return only entries
11162 which are directories. This is done by stat()ing each entry, so it
11163 causes more disk I/O.
11164 (For systems setting struct @samp{dirent->d_type} this check is free
11165 and it's done always regardless of this setting).
11166 Defaults to @samp{#f}.
11169 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
11170 When copying a message, do it with hard links whenever possible.
11171 This makes the performance much better, and it's unlikely to have any
11173 Defaults to @samp{#t}.
11176 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
11177 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
11178 directory only when its mtime changes unexpectedly or when we can't find
11179 the mail otherwise.
11180 Defaults to @samp{#f}.
11183 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
11184 Which locking methods to use for locking mbox. There are four
11189 Create <mailbox>.lock file. This is the oldest and most NFS-safe
11190 solution. If you want to use /var/mail/ like directory, the users will
11191 need write access to that directory.
11193 Same as dotlock, but if it fails because of permissions or because there
11194 isn't enough disk space, just skip it.
11196 Use this if possible. Works with NFS too if lockd is used.
11198 May not exist in all systems. Doesn't work with NFS.
11200 May not exist in all systems. Doesn't work with NFS.
11203 You can use multiple locking methods; if you do the order they're declared
11204 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
11205 locking methods as well. Some operating systems don't allow using some of
11206 them simultaneously.
11209 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
11213 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
11214 Maximum time to wait for lock (all of them) before aborting.
11215 Defaults to @samp{"5 mins"}.
11218 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
11219 If dotlock exists but the mailbox isn't modified in any way,
11220 override the lock file after this much time.
11221 Defaults to @samp{"2 mins"}.
11224 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
11225 When mbox changes unexpectedly we have to fully read it to find out
11226 what changed. If the mbox is large this can take a long time. Since
11227 the change is usually just a newly appended mail, it'd be faster to
11228 simply read the new mails. If this setting is enabled, Dovecot does
11229 this but still safely fallbacks to re-reading the whole mbox file
11230 whenever something in mbox isn't how it's expected to be. The only real
11231 downside to this setting is that if some other MUA changes message
11232 flags, Dovecot doesn't notice it immediately. Note that a full sync is
11233 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
11234 Defaults to @samp{#t}.
11237 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
11238 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
11239 EXAMINE, EXPUNGE or CHECK commands. If this is set,
11240 @samp{mbox-dirty-syncs} is ignored.
11241 Defaults to @samp{#f}.
11244 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
11245 Delay writing mbox headers until doing a full write sync (EXPUNGE
11246 and CHECK commands and when closing the mailbox). This is especially
11247 useful for POP3 where clients often delete all mails. The downside is
11248 that our changes aren't immediately visible to other MUAs.
11249 Defaults to @samp{#t}.
11252 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
11253 If mbox size is smaller than this (e.g. 100k), don't write index
11254 files. If an index file already exists it's still read, just not
11256 Defaults to @samp{0}.
11259 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
11260 Maximum dbox file size until it's rotated.
11261 Defaults to @samp{2000000}.
11264 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
11265 Maximum dbox file age until it's rotated. Typically in days. Day
11266 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
11268 Defaults to @samp{"1d"}.
11271 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
11272 When creating new mdbox files, immediately preallocate their size to
11273 @samp{mdbox-rotate-size}. This setting currently works only in Linux
11274 with some file systems (ext4, xfs).
11275 Defaults to @samp{#f}.
11278 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
11279 sdbox and mdbox support saving mail attachments to external files,
11280 which also allows single instance storage for them. Other backends
11281 don't support this for now.
11283 WARNING: This feature hasn't been tested much yet. Use at your own risk.
11285 Directory root where to store mail attachments. Disabled, if empty.
11286 Defaults to @samp{""}.
11289 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
11290 Attachments smaller than this aren't saved externally. It's also
11291 possible to write a plugin to disable saving specific attachments
11293 Defaults to @samp{128000}.
11296 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
11297 File system backend to use for saving attachments:
11300 No SiS done by Dovecot (but this might help FS's own deduplication)
11302 SiS with immediate byte-by-byte comparison during saving
11303 @item sis-queue posix
11304 SiS with delayed comparison and deduplication.
11306 Defaults to @samp{"sis posix"}.
11309 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
11310 Hash format to use in attachment filenames. You can add any text and
11311 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
11312 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
11313 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
11314 Defaults to @samp{"%@{sha1@}"}.
11317 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
11319 Defaults to @samp{100}.
11322 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
11324 Defaults to @samp{1000}.
11327 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
11328 Default VSZ (virtual memory size) limit for service processes.
11329 This is mainly intended to catch and kill processes that leak memory
11330 before they eat up everything.
11331 Defaults to @samp{256000000}.
11334 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
11335 Login user is internally used by login processes. This is the most
11336 untrusted user in Dovecot system. It shouldn't have access to anything
11338 Defaults to @samp{"dovenull"}.
11341 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
11342 Internal user is used by unprivileged processes. It should be
11343 separate from login user, so that login processes can't disturb other
11345 Defaults to @samp{"dovecot"}.
11348 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
11349 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
11350 Defaults to @samp{"required"}.
11353 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
11354 PEM encoded X.509 SSL/TLS certificate (public key).
11355 Defaults to @samp{"</etc/dovecot/default.pem"}.
11358 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
11359 PEM encoded SSL/TLS private key. The key is opened before
11360 dropping root privileges, so keep the key file unreadable by anyone but
11362 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
11365 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
11366 If key file is password protected, give the password here.
11367 Alternatively give it when starting dovecot with -p parameter. Since
11368 this file is often world-readable, you may want to place this setting
11369 instead to a different.
11370 Defaults to @samp{""}.
11373 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
11374 PEM encoded trusted certificate authority. Set this only if you
11375 intend to use @samp{ssl-verify-client-cert? #t}. The file should
11376 contain the CA certificate(s) followed by the matching
11377 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
11378 Defaults to @samp{""}.
11381 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
11382 Require that CRL check succeeds for client certificates.
11383 Defaults to @samp{#t}.
11386 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
11387 Request client to send a certificate. If you also want to require
11388 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
11389 Defaults to @samp{#f}.
11392 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
11393 Which field from certificate to use for username. commonName and
11394 x500UniqueIdentifier are the usual choices. You'll also need to set
11395 @samp{auth-ssl-username-from-cert? #t}.
11396 Defaults to @samp{"commonName"}.
11399 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
11400 How often to regenerate the SSL parameters file. Generation is
11401 quite CPU intensive operation. The value is in hours, 0 disables
11402 regeneration entirely.
11403 Defaults to @samp{168}.
11406 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
11407 SSL protocols to use.
11408 Defaults to @samp{"!SSLv2"}.
11411 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
11412 SSL ciphers to use.
11413 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
11416 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
11417 SSL crypto device to use, for valid values run "openssl engine".
11418 Defaults to @samp{""}.
11421 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
11422 Address to use when sending rejection mails.
11423 %d expands to recipient domain.
11424 Defaults to @samp{"postmaster@@%d"}.
11427 @deftypevr {@code{dovecot-configuration} parameter} string hostname
11428 Hostname to use in various parts of sent mails (e.g. in Message-Id)
11429 and in LMTP replies. Default is the system's real hostname@@domain.
11430 Defaults to @samp{""}.
11433 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
11434 If user is over quota, return with temporary failure instead of
11436 Defaults to @samp{#f}.
11439 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
11440 Binary to use for sending mails.
11441 Defaults to @samp{"/usr/sbin/sendmail"}.
11444 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
11445 If non-empty, send mails via this SMTP host[:port] instead of
11447 Defaults to @samp{""}.
11450 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
11451 Subject: header to use for rejection mails. You can use the same
11452 variables as for @samp{rejection-reason} below.
11453 Defaults to @samp{"Rejected: %s"}.
11456 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
11457 Human readable error message for rejection mails. You can use
11470 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
11473 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
11474 Delimiter character between local-part and detail in email
11476 Defaults to @samp{"+"}.
11479 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
11480 Header where the original recipient address (SMTP's RCPT TO:
11481 address) is taken from if not available elsewhere. With dovecot-lda -a
11482 parameter overrides this. A commonly used header for this is
11484 Defaults to @samp{""}.
11487 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
11488 Should saving a mail to a nonexistent mailbox automatically create
11490 Defaults to @samp{#f}.
11493 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
11494 Should automatically created mailboxes be also automatically
11496 Defaults to @samp{#f}.
11499 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
11500 Maximum IMAP command line length. Some clients generate very long
11501 command lines with huge mailboxes, so you may need to raise this if you
11502 get "Too long argument" or "IMAP command line too large" errors
11504 Defaults to @samp{64000}.
11507 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
11508 IMAP logout format string:
11511 total number of bytes read from client
11513 total number of bytes sent to client.
11515 Defaults to @samp{"in=%i out=%o"}.
11518 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
11519 Override the IMAP CAPABILITY response. If the value begins with '+',
11520 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
11521 Defaults to @samp{""}.
11524 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
11525 How long to wait between "OK Still here" notifications when client
11527 Defaults to @samp{"2 mins"}.
11530 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
11531 ID field names and values to send to clients. Using * as the value
11532 makes Dovecot use the default value. The following fields have default
11533 values currently: name, version, os, os-version, support-url,
11535 Defaults to @samp{""}.
11538 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
11539 ID fields sent by client to log. * means everything.
11540 Defaults to @samp{""}.
11543 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
11544 Workarounds for various client bugs:
11547 @item delay-newmail
11548 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
11549 CHECK commands. Some clients ignore them otherwise, for example OSX
11550 Mail (<v2.1). Outlook Express breaks more badly though, without this it
11551 may show user "Message no longer in server" errors. Note that OE6
11552 still breaks even with this workaround if synchronization is set to
11555 @item tb-extra-mailbox-sep
11556 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
11557 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
11558 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
11560 @item tb-lsub-flags
11561 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
11562 This makes Thunderbird realize they aren't selectable and show them
11563 greyed out, instead of only later giving "not selectable" popup error.
11565 Defaults to @samp{()}.
11568 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
11569 Host allowed in URLAUTH URLs sent by client. "*" allows all.
11570 Defaults to @samp{""}.
11574 Whew! Lots of configuration options. The nice thing about it though is
11575 that GuixSD has a complete interface to Dovecot's configuration
11576 language. This allows not only a nice way to declare configurations,
11577 but also offers reflective capabilities as well: users can write code to
11578 inspect and transform configurations from within Scheme.
11580 However, it could be that you just want to get a @code{dovecot.conf} up
11581 and running. In that case, you can pass an
11582 @code{opaque-dovecot-configuration} as the @code{#:config} parameter to
11583 @code{dovecot-service}. As its name indicates, an opaque configuration
11584 does not have easy reflective capabilities.
11586 Available @code{opaque-dovecot-configuration} fields are:
11588 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
11589 The dovecot package.
11592 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
11593 The contents of the @code{dovecot.conf}, as a string.
11596 For example, if your @code{dovecot.conf} is just the empty string, you
11597 could instantiate a dovecot service like this:
11600 (dovecot-service #:config
11601 (opaque-dovecot-configuration
11605 @subsubheading OpenSMTPD Service
11607 @deffn {Scheme Variable} opensmtpd-service-type
11608 This is the type of the @uref{https://www.opensmtpd.org, OpenSMTPD}
11609 service, whose value should be an @code{opensmtpd-configuration} object
11610 as in this example:
11613 (service opensmtpd-service-type
11614 (opensmtpd-configuration
11615 (config-file (local-file "./my-smtpd.conf"))))
11619 @deftp {Data Type} opensmtpd-configuration
11620 Data type regresenting the configuration of opensmtpd.
11623 @item @code{package} (default: @var{opensmtpd})
11624 Package object of the OpenSMTPD SMTP server.
11626 @item @code{config-file} (default: @var{%default-opensmtpd-file})
11627 File-like object of the OpenSMTPD configuration file to use. By default
11628 it listens on the loopback network interface, and allows for mail from
11629 users and daemons on the local machine, as well as permitting email to
11630 remote servers. Run @command{man smtpd.conf} for more information.
11635 @node Kerberos Services
11636 @subsubsection Kerberos Services
11639 The @code{(gnu services kerberos)} module provides services relating to
11640 the authentication protocol @dfn{Kerberos}.
11642 @subsubheading Krb5 Service
11644 Programs using a Kerberos client library normally
11645 expect a configuration file in @file{/etc/krb5.conf}.
11646 This service generates such a file from a definition provided in the
11647 operating system declaration.
11648 It does not cause any daemon to be started.
11650 No ``keytab'' files are provided by this service---you must explicitly create them.
11651 This service is known to work with the MIT client library, @code{mit-krb5}.
11652 Other implementations have not been tested.
11654 @defvr {Scheme Variable} krb5-service-type
11655 A service type for Kerberos 5 clients.
11659 Here is an example of its use:
11661 (service krb5-service-type
11662 (krb5-configuration
11663 (default-realm "EXAMPLE.COM")
11664 (allow-weak-crypto? #t)
11667 (name "EXAMPLE.COM")
11668 (admin-server "groucho.example.com")
11669 (kdc "karl.example.com"))
11672 (admin-server "kerb-admin.argrx.edu")
11673 (kdc "keys.argrx.edu"))))))
11677 This example provides a Kerberos@tie{}5 client configuration which:
11679 @item Recognizes two realms, @i{viz:} ``EXAMPLE.COM'' and ``ARGRX.EDU'', both
11680 of which have distinct administration servers and key distribution centers;
11681 @item Will default to the realm ``EXAMPLE.COM'' if the realm is not explicitly
11682 specified by clients;
11683 @item Accepts services which only support encryption types known to be weak.
11686 The @code{krb5-realm} and @code{krb5-configuration} types have many fields.
11687 Only the most commonly used ones are described here.
11688 For a full list, and more detailed explanation of each, see the MIT
11689 @uref{http://web.mit.edu/kerberos/krb5-devel/doc/admin/conf_files/krb5_conf.html,,krb5.conf}
11693 @deftp {Data Type} krb5-realm
11694 @cindex realm, kerberos
11697 This field is a string identifying the name of the realm.
11698 A common convention is to use the fully qualified DNS name of your organization,
11699 converted to upper case.
11701 @item @code{admin-server}
11702 This field is a string identifying the host where the administration server is
11706 This field is a string identifying the key distribution center
11711 @deftp {Data Type} krb5-configuration
11714 @item @code{allow-weak-crypto?} (default: @code{#f})
11715 If this flag is @code{#t} then services which only offer encryption algorithms
11716 known to be weak will be accepted.
11718 @item @code{default-realm} (default: @code{#f})
11719 This field should be a string identifying the default Kerberos
11720 realm for the client.
11721 You should set this field to the name of your Kerberos realm.
11722 If this value is @code{#f}
11723 then a realm must be specified with every Kerberos principal when invoking programs
11724 such as @command{kinit}.
11726 @item @code{realms}
11727 This should be a non-empty list of @code{krb5-realm} objects, which clients may
11729 Normally, one of them will have a @code{name} field matching the @code{default-realm}
11735 @subsubheading PAM krb5 Service
11738 The @code{pam-krb5} service allows for login authentication and password
11739 management via Kerberos.
11740 You will need this service if you want PAM enabled applications to authenticate
11741 users using Kerberos.
11743 @defvr {Scheme Variable} pam-krb5-service-type
11744 A service type for the Kerberos 5 PAM module.
11747 @deftp {Data Type} pam-krb5-configuration
11748 Data type representing the configuration of the Kerberos 5 PAM module
11749 This type has the following parameters:
11751 @item @code{pam-krb5} (default: @code{pam-krb5})
11752 The pam-krb5 package to use.
11754 @item @code{minimum-uid} (default: @code{1000})
11755 The smallest user ID for which Kerberos authentications should be attempted.
11756 Local accounts with lower values will silently fail to authenticate.
11762 @subsubsection Web Services
11767 The @code{(gnu services web)} module provides the following service:
11769 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
11770 [#:log-directory ``/var/log/nginx''] @
11771 [#:run-directory ``/var/run/nginx''] @
11772 [#:vhost-list (list (nginx-vhost-configuration))] @
11775 Return a service that runs @var{nginx}, the nginx web server.
11777 The nginx daemon loads its runtime configuration from @var{config-file}.
11778 Log files are written to @var{log-directory} and temporary runtime data
11779 files are written to @var{run-directory}. For proper operation, these
11780 arguments should match what is in @var{config-file} to ensure that the
11781 directories are created when the service is activated.
11783 As an alternative to using a @var{config-file}, @var{vhost-list} can be
11784 used to specify the list of @dfn{virtual hosts} required on the host. For
11785 this to work, use the default value for @var{config-file}.
11789 @deftp {Data Type} nginx-vhost-configuration
11790 Data type representing the configuration of an nginx virtual host.
11791 This type has the following parameters:
11794 @item @code{http-port} (default: @code{80})
11795 Nginx will listen for HTTP connection on this port. Set it at @code{#f} if
11796 nginx should not listen for HTTP (non secure) connection for this
11797 @dfn{virtual host}.
11799 @item @code{https-port} (default: @code{443})
11800 Nginx will listen for HTTPS connection on this port. Set it at @code{#f} if
11801 nginx should not listen for HTTPS (secure) connection for this @dfn{virtual host}.
11803 Note that nginx can listen for HTTP and HTTPS connections in the same
11804 @dfn{virtual host}.
11806 @item @code{server-name} (default: @code{(list 'default)})
11807 A list of server names this vhost represents. @code{'default} represents the
11808 default vhost for connections matching no other vhost.
11810 @item @code{root} (default: @code{"/srv/http"})
11811 Root of the website nginx will serve.
11813 @item @code{index} (default: @code{(list "index.html")})
11814 Index files to look for when clients ask for a directory. If it cannot be found,
11815 Nginx will send the list of files in the directory.
11817 @item @code{ssl-certificate} (default: @code{"/etc/nginx/cert.pem"})
11818 Where to find the certificate for secure connections. Set it to @code{#f} if
11819 you don't have a certificate or you don't want to use HTTPS.
11821 @item @code{ssl-certificate-key} (default: @code{"/etc/nginx/key.pem"})
11822 Where to find the private key for secure connections. Set it to @code{#f} if
11823 you don't have a key or you don't want to use HTTPS.
11825 @item @code{server-tokens?} (default: @code{#f})
11826 Whether the server should add its configuration to response.
11831 @node Network File System
11832 @subsubsection Network File System
11835 The @code{(gnu services nfs)} module provides the following services,
11836 which are most commonly used in relation to mounting or exporting
11837 directory trees as @dfn{network file systems} (NFS).
11839 @subsubheading RPC Bind Service
11842 The RPC Bind service provides a facility to map program numbers into
11843 universal addresses.
11844 Many NFS related services use this facility. Hence it is automatically
11845 started when a dependent service starts.
11847 @defvr {Scheme Variable} rpcbind-service-type
11848 A service type for the RPC portmapper daemon.
11852 @deftp {Data Type} rpcbind-configuration
11853 Data type representing the configuration of the RPC Bind Service.
11854 This type has the following parameters:
11856 @item @code{rpcbind} (default: @code{rpcbind})
11857 The rpcbind package to use.
11859 @item @code{warm-start?} (default: @code{#t})
11860 If this parameter is @code{#t}, then the daemon will read a
11861 state file on startup thus reloading state information saved by a previous
11867 @subsubheading Pipefs Pseudo File System
11871 The pipefs file system is used to transfer NFS related data
11872 between the kernel and user space programs.
11874 @defvr {Scheme Variable} pipefs-service-type
11875 A service type for the pipefs pseudo file system.
11878 @deftp {Data Type} pipefs-configuration
11879 Data type representing the configuration of the pipefs pseudo file system service.
11880 This type has the following parameters:
11882 @item @code{mount-point} (default: @code{"/var/lib/nfs/rpc_pipefs"})
11883 The directory to which the file system is to be attached.
11888 @subsubheading GSS Daemon Service
11891 @cindex global security system
11893 The @dfn{global security system} (GSS) daemon provides strong security for RPC
11895 Before exchanging RPC requests an RPC client must establish a security
11896 context. Typically this is done using the Kerberos command @command{kinit}
11897 or automatically at login time using PAM services (@pxref{Kerberos Services}).
11899 @defvr {Scheme Variable} gss-service-type
11900 A service type for the Global Security System (GSS) daemon.
11903 @deftp {Data Type} gss-configuration
11904 Data type representing the configuration of the GSS daemon service.
11905 This type has the following parameters:
11907 @item @code{nfs-utils} (default: @code{nfs-utils})
11908 The package in which the @command{rpc.gssd} command is to be found.
11910 @item @code{pipefs-directory} (default: @code{"/var/lib/nfs/rpc_pipefs"})
11911 The directory where the pipefs file system is mounted.
11917 @subsubheading IDMAP Daemon Service
11919 @cindex name mapper
11921 The idmap daemon service provides mapping between user IDs and user names.
11922 Typically it is required in order to access file systems mounted via NFSv4.
11924 @defvr {Scheme Variable} idmap-service-type
11925 A service type for the Identity Mapper (IDMAP) daemon.
11928 @deftp {Data Type} idmap-configuration
11929 Data type representing the configuration of the IDMAP daemon service.
11930 This type has the following parameters:
11932 @item @code{nfs-utils} (default: @code{nfs-utils})
11933 The package in which the @command{rpc.idmapd} command is to be found.
11935 @item @code{pipefs-directory} (default: @code{"/var/lib/nfs/rpc_pipefs"})
11936 The directory where the pipefs file system is mounted.
11938 @item @code{domain} (default: @code{#f})
11939 The local NFSv4 domain name.
11940 This must be a string or @code{#f}.
11941 If it is @code{#f} then the daemon will use the host's fully qualified domain name.
11946 @node Continuous Integration
11947 @subsubsection Continuous Integration
11949 @cindex continuous integration
11950 @uref{https://notabug.org/mthl/cuirass, Cuirass} is a continuous
11951 integration tool for Guix. It can be used both for development and for
11952 providing substitutes to others (@pxref{Substitutes}).
11954 The @code{(gnu services cuirass)} module provides the following service.
11956 @deffn {Scheme Procedure} cuirass-service @
11957 [#:config @code{(cuirass-configuration)}]
11958 Return a service that runs @command{cuirass}.
11960 The @var{#:config} keyword argument specifies the configuration for
11961 @command{cuirass}, which must be a @code{<cuirass-configuration>}
11962 object, by default it doesn't provide any build job. If you want to
11963 provide your own configuration you will most likely use the
11964 @code{cuirass-configuration} special form which returns such objects.
11967 In order to add build jobs you will have to set the
11968 @code{specifications} field. Here is an example of a cuirass service
11969 defining a build job based on a specification that can be found in
11970 Cuirass source tree.
11973 (let ((spec `((#:name . "guix")
11974 (#:url . "git://git.savannah.gnu.org/guix.git")
11975 (#:load-path . ".")
11976 ;; Adapt to a valid absolute file name.
11977 (#:file . "/.../cuirass/tests/gnu-system.scm")
11978 (#:proc . hydra-jobs)
11979 (#:arguments (subset . "hello"))
11980 (#:branch . "master"))))
11981 (cuirass-service #:config (cuirass-configuration
11982 (specifications (list spec)))))
11985 While information related to build jobs are located directly in the
11986 specifications, global settings for the @command{cuirass} process are
11987 accessible in other @code{cuirass-configuration} fields.
11989 @deftp {Data Type} cuirass-configuration
11990 Data type representing the configuration of Cuirass.
11993 @item @code{log-file} (default: @code{"/var/log/cuirass.log"})
11994 Location of the log file.
11996 @item @code{cache-directory} (default: @code{"/var/cache/cuirass"})
11997 Location of the repository cache.
11999 @item @code{user} (default: @code{"cuirass"})
12000 Owner of the @code{cuirass} process.
12002 @item @code{group} (default: @code{"cuirass"})
12003 Owner's group of the @code{cuirass} process.
12005 @item @code{interval} (default: @code{60})
12006 Number of seconds between the poll of the repositories followed by the
12009 @item @code{database} (default: @code{"/var/run/cuirass/cuirass.db"})
12010 Location of sqlite database which contains the build results and previously
12011 added specifications.
12013 @item @code{specifications} (default: @code{'()})
12014 A list of specifications, where a specification is an association list
12015 (@pxref{Associations Lists,,, guile, GNU Guile Reference Manual}) whose
12016 keys are keywords (@code{#:keyword-example}) as shown in the example
12019 @item @code{use-substitutes?} (default: @code{#f})
12020 This allows using substitutes to avoid building every dependencies of a job
12023 @item @code{one-shot?} (default: @code{#f})
12024 Only evaluate specifications and build derivations once.
12028 @node Miscellaneous Services
12029 @subsubsection Miscellaneous Services
12033 @subsubheading Lirc Service
12035 The @code{(gnu services lirc)} module provides the following service.
12037 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
12038 [#:device #f] [#:driver #f] [#:config-file #f] @
12039 [#:extra-options '()]
12040 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
12041 decodes infrared signals from remote controls.
12043 Optionally, @var{device}, @var{driver} and @var{config-file}
12044 (configuration file name) may be specified. See @command{lircd} manual
12047 Finally, @var{extra-options} is a list of additional command-line options
12048 passed to @command{lircd}.
12052 @subsubheading Spice Service
12054 The @code{(gnu services spice)} module provides the following service.
12056 @deffn {Scheme Procedure} spice-vdagent-service [#:spice-vdagent]
12057 Returns a service that runs @url{http://www.spice-space.org,VDAGENT}, a daemon
12058 that enables sharing the clipboard with a vm and setting the guest display
12059 resolution when the graphical console window resizes.
12062 @subsubsection Dictionary Services
12064 The @code{(gnu services dict)} module provides the following service:
12066 @deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)]
12067 Return a service that runs the @command{dicod} daemon, an implementation
12068 of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}).
12070 The optional @var{config} argument specifies the configuration for
12071 @command{dicod}, which should be a @code{<dicod-configuration>} object, by
12072 default it serves the GNU Collaborative International Dictonary of English.
12074 You can add @command{open localhost} to your @file{~/.dico} file to make
12075 @code{localhost} the default server for @command{dico} client
12076 (@pxref{Initialization File,,, dico, GNU Dico Manual}).
12079 @deftp {Data Type} dicod-configuration
12080 Data type representing the configuration of dicod.
12083 @item @code{dico} (default: @var{dico})
12084 Package object of the GNU Dico dictionary server.
12086 @item @code{interfaces} (default: @var{'("localhost")})
12087 This is the list of IP addresses and ports and possibly socket file
12088 names to listen to (@pxref{Server Settings, @code{listen} directive,,
12089 dico, GNU Dico Manual}).
12091 @item @code{databases} (default: @var{(list %dicod-database:gcide)})
12092 List of @code{<dicod-database>} objects denoting dictionaries to be served.
12096 @deftp {Data Type} dicod-database
12097 Data type representing a dictionary database.
12101 Name of the database, will be used in DICT commands.
12103 @item @code{module}
12104 Name of the dicod module used by this database
12105 (@pxref{Modules,,, dico, GNU Dico Manual}).
12107 @item @code{options}
12108 List of strings or gexps representing the arguments for the module handler
12109 (@pxref{Handlers,,, dico, GNU Dico Manual}).
12113 @defvr {Scheme Variable} %dicod-database:gcide
12114 A @code{<dicod-database>} object serving the GNU Collaborative International
12115 Dictonary of English using the @code{gcide} package.
12118 @subsubsection Version Control
12120 The @code{(gnu services version-control)} module provides the following services:
12122 @subsubheading Git daemon service
12124 @deffn {Scheme Procedure} git-daemon-service [#:config (git-daemon-configuration)]
12126 Return a service that runs @command{git daemon}, a simple TCP server to
12127 expose repositiories over the Git protocol for annoymous access.
12129 The optional @var{config} argument should be a
12130 @code{<git-daemon-configuration>} object, by default it allows read-only
12131 access to exported@footnote{By creating the magic file
12132 "git-daemon-export-ok" in the repository directory.} repositories under
12137 @deftp {Data Type} git-daemon-configuration
12138 Data type representing the configuration for @code{git-daemon-service}.
12141 @item @code{package} (default: @var{git})
12142 Package object of the Git distributed version control system.
12144 @item @code{export-all?} (default: @var{#f})
12145 Whether to allow access for all Git repositories, even if they do not
12146 have the @file{git-daemon-export-ok} file.
12148 @item @code{base-path} (default: @file{/srv/git})
12149 Whether to remap all the path requests as relative to the given path.
12150 If you run git daemon with @var{(base-path "/srv/git")} on example.com,
12151 then if you later try to pull @code{git://example.com/hello.git}, git
12152 daemon will interpret the path as @code{/srv/git/hello.git}.
12154 @item @code{user-path} (default: @var{#f})
12155 Whether to allow @code{~user} notation to be used in requests. When
12156 specified with empty string, requests to @code{git://host/~alice/foo} is
12157 taken as a request to access @code{foo} repository in the home directory
12158 of user @code{alice}. If @var{(user-path "path")} is specified, the
12159 same request is taken as a request to access @code{path/foo} repository
12160 in the home directory of user @code{alice}.
12162 @item @code{listen} (default: @var{'()})
12163 Whether to listen on specific IP addresses or hostnames, defaults to
12166 @item @code{port} (default: @var{#f})
12167 Whether to listen on an alternative port, which defaults to 9418.
12169 @item @code{whitelist} (default: @var{'()})
12170 If not empty, only allow access to this list of directories.
12172 @item @code{extra-options} (default: @var{'()})
12173 Extra options will be passed to @code{git daemon}, please run
12174 @command{man git-daemon} for more information.
12179 @node Setuid Programs
12180 @subsection Setuid Programs
12182 @cindex setuid programs
12183 Some programs need to run with ``root'' privileges, even when they are
12184 launched by unprivileged users. A notorious example is the
12185 @command{passwd} program, which users can run to change their
12186 password, and which needs to access the @file{/etc/passwd} and
12187 @file{/etc/shadow} files---something normally restricted to root, for
12188 obvious security reasons. To address that, these executables are
12189 @dfn{setuid-root}, meaning that they always run with root privileges
12190 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
12191 for more info about the setuid mechanism.)
12193 The store itself @emph{cannot} contain setuid programs: that would be a
12194 security issue since any user on the system can write derivations that
12195 populate the store (@pxref{The Store}). Thus, a different mechanism is
12196 used: instead of changing the setuid bit directly on files that are in
12197 the store, we let the system administrator @emph{declare} which programs
12198 should be setuid root.
12200 The @code{setuid-programs} field of an @code{operating-system}
12201 declaration contains a list of G-expressions denoting the names of
12202 programs to be setuid-root (@pxref{Using the Configuration System}).
12203 For instance, the @command{passwd} program, which is part of the Shadow
12204 package, can be designated by this G-expression (@pxref{G-Expressions}):
12207 #~(string-append #$shadow "/bin/passwd")
12210 A default set of setuid programs is defined by the
12211 @code{%setuid-programs} variable of the @code{(gnu system)} module.
12213 @defvr {Scheme Variable} %setuid-programs
12214 A list of G-expressions denoting common programs that are setuid-root.
12216 The list includes commands such as @command{passwd}, @command{ping},
12217 @command{su}, and @command{sudo}.
12220 Under the hood, the actual setuid programs are created in the
12221 @file{/run/setuid-programs} directory at system activation time. The
12222 files in this directory refer to the ``real'' binaries, which are in the
12225 @node X.509 Certificates
12226 @subsection X.509 Certificates
12228 @cindex HTTPS, certificates
12229 @cindex X.509 certificates
12231 Web servers available over HTTPS (that is, HTTP over the transport-layer
12232 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
12233 that the client can then use to @emph{authenticate} the server. To do
12234 that, clients verify that the server's certificate is signed by a
12235 so-called @dfn{certificate authority} (CA). But to verify the CA's
12236 signature, clients must have first acquired the CA's certificate.
12238 Web browsers such as GNU@tie{}IceCat include their own set of CA
12239 certificates, such that they are able to verify CA signatures
12242 However, most other programs that can talk HTTPS---@command{wget},
12243 @command{git}, @command{w3m}, etc.---need to be told where CA
12244 certificates can be found.
12246 @cindex @code{nss-certs}
12247 In GuixSD, this is done by adding a package that provides certificates
12248 to the @code{packages} field of the @code{operating-system} declaration
12249 (@pxref{operating-system Reference}). GuixSD includes one such package,
12250 @code{nss-certs}, which is a set of CA certificates provided as part of
12251 Mozilla's Network Security Services.
12253 Note that it is @emph{not} part of @var{%base-packages}, so you need to
12254 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
12255 most applications and libraries look for certificates by default, points
12256 to the certificates installed globally.
12258 Unprivileged users, including users of Guix on a foreign distro,
12259 can also install their own certificate package in
12260 their profile. A number of environment variables need to be defined so
12261 that applications and libraries know where to find them. Namely, the
12262 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
12263 variables. Some applications add their own environment variables; for
12264 instance, the Git version control system honors the certificate bundle
12265 pointed to by the @code{GIT_SSL_CAINFO} environment variable. Thus, you
12266 would typically run something like:
12269 $ guix package -i nss-certs
12270 $ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
12271 $ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
12272 $ export GIT_SSL_CAINFO="$SSL_CERT_FILE"
12275 @node Name Service Switch
12276 @subsection Name Service Switch
12278 @cindex name service switch
12280 The @code{(gnu system nss)} module provides bindings to the
12281 configuration file of the libc @dfn{name service switch} or @dfn{NSS}
12282 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
12283 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
12284 extended with new ``name'' lookup methods for system databases, which
12285 includes host names, service names, user accounts, and more (@pxref{Name
12286 Service Switch, System Databases and Name Service Switch,, libc, The GNU
12287 C Library Reference Manual}).
12289 The NSS configuration specifies, for each system database, which lookup
12290 method is to be used, and how the various methods are chained
12291 together---for instance, under which circumstances NSS should try the
12292 next method in the list. The NSS configuration is given in the
12293 @code{name-service-switch} field of @code{operating-system} declarations
12294 (@pxref{operating-system Reference, @code{name-service-switch}}).
12297 @cindex .local, host name lookup
12298 As an example, the declaration below configures the NSS to use the
12299 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
12300 back-end}, which supports host name lookups over multicast DNS (mDNS)
12301 for host names ending in @code{.local}:
12304 (name-service-switch
12305 (hosts (list %files ;first, check /etc/hosts
12307 ;; If the above did not succeed, try
12308 ;; with 'mdns_minimal'.
12310 (name "mdns_minimal")
12312 ;; 'mdns_minimal' is authoritative for
12313 ;; '.local'. When it returns "not found",
12314 ;; no need to try the next methods.
12315 (reaction (lookup-specification
12316 (not-found => return))))
12318 ;; Then fall back to DNS.
12322 ;; Finally, try with the "full" 'mdns'.
12327 Do not worry: the @code{%mdns-host-lookup-nss} variable (see below)
12328 contains this configuration, so you will not have to type it if all you
12329 want is to have @code{.local} host lookup working.
12331 Note that, in this case, in addition to setting the
12332 @code{name-service-switch} of the @code{operating-system} declaration,
12333 you also need to use @code{avahi-service} (@pxref{Networking Services,
12334 @code{avahi-service}}), or @var{%desktop-services}, which includes it
12335 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
12336 to the name service cache daemon (@pxref{Base Services,
12337 @code{nscd-service}}).
12339 For convenience, the following variables provide typical NSS
12342 @defvr {Scheme Variable} %default-nss
12343 This is the default name service switch configuration, a
12344 @code{name-service-switch} object.
12347 @defvr {Scheme Variable} %mdns-host-lookup-nss
12348 This is the name service switch configuration with support for host name
12349 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
12352 The reference for name service switch configuration is given below. It
12353 is a direct mapping of the configuration file format of the C library , so
12354 please refer to the C library manual for more information (@pxref{NSS
12355 Configuration File,,, libc, The GNU C Library Reference Manual}).
12356 Compared to the configuration file format of libc NSS, it has the advantage
12357 not only of adding this warm parenthetic feel that we like, but also
12358 static checks: you will know about syntax errors and typos as soon as you
12359 run @command{guix system}.
12361 @deftp {Data Type} name-service-switch
12363 This is the data type representation the configuration of libc's name
12364 service switch (NSS). Each field below represents one of the supported
12381 The system databases handled by the NSS. Each of these fields must be a
12382 list of @code{<name-service>} objects (see below).
12386 @deftp {Data Type} name-service
12388 This is the data type representing an actual name service and the
12389 associated lookup action.
12393 A string denoting the name service (@pxref{Services in the NSS
12394 configuration,,, libc, The GNU C Library Reference Manual}).
12396 Note that name services listed here must be visible to nscd. This is
12397 achieved by passing the @code{#:name-services} argument to
12398 @code{nscd-service} the list of packages providing the needed name
12399 services (@pxref{Base Services, @code{nscd-service}}).
12402 An action specified using the @code{lookup-specification} macro
12403 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
12404 Reference Manual}). For example:
12407 (lookup-specification (unavailable => continue)
12408 (success => return))
12413 @node Initial RAM Disk
12414 @subsection Initial RAM Disk
12417 @cindex initial RAM disk
12418 For bootstrapping purposes, the Linux-Libre kernel is passed an
12419 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
12420 root file system as well as an initialization script. The latter is
12421 responsible for mounting the real root file system, and for loading any
12422 kernel modules that may be needed to achieve that.
12424 The @code{initrd} field of an @code{operating-system} declaration allows
12425 you to specify which initrd you would like to use. The @code{(gnu
12426 system linux-initrd)} module provides two ways to build an initrd: the
12427 high-level @code{base-initrd} procedure, and the low-level
12428 @code{expression->initrd} procedure.
12430 The @code{base-initrd} procedure is intended to cover most common uses.
12431 For example, if you want to add a bunch of kernel modules to be loaded
12432 at boot time, you can define the @code{initrd} field of the operating
12433 system declaration like this:
12436 (initrd (lambda (file-systems . rest)
12437 ;; Create a standard initrd that has modules "foo.ko"
12438 ;; and "bar.ko", as well as their dependencies, in
12439 ;; addition to the modules available by default.
12440 (apply base-initrd file-systems
12441 #:extra-modules '("foo" "bar")
12445 The @code{base-initrd} procedure also handles common use cases that
12446 involves using the system as a QEMU guest, or as a ``live'' system with
12447 volatile root file system.
12449 The initial RAM disk produced by @code{base-initrd} honors several
12450 options passed on the Linux kernel command line (that is, arguments
12451 passed @i{via} the @code{linux} command of GRUB, or the
12452 @code{-append} option of QEMU), notably:
12455 @item --load=@var{boot}
12456 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
12457 program, once it has mounted the root file system.
12459 GuixSD uses this option to yield control to a boot program that runs the
12460 service activation programs and then spawns the GNU@tie{}Shepherd, the
12461 initialization system.
12463 @item --root=@var{root}
12464 Mount @var{root} as the root file system. @var{root} can be a
12465 device name like @code{/dev/sda1}, a partition label, or a partition
12468 @item --system=@var{system}
12469 Have @file{/run/booted-system} and @file{/run/current-system} point to
12472 @item modprobe.blacklist=@var{modules}@dots{}
12473 @cindex module, black-listing
12474 @cindex black list, of kernel modules
12475 Instruct the initial RAM disk as well as the @command{modprobe} command
12476 (from the kmod package) to refuse to load @var{modules}. @var{modules}
12477 must be a comma-separated list of module names---e.g.,
12478 @code{usbkbd,9pnet}.
12481 Start a read-eval-print loop (REPL) from the initial RAM disk before it
12482 tries to load kernel modules and to mount the root file system. Our
12483 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
12484 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
12485 Manual}, for more information on Guile's REPL.
12489 Now that you know all the features that initial RAM disks produced by
12490 @code{base-initrd} provide, here is how to use it and customize it
12494 @cindex initial RAM disk
12495 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
12496 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
12497 [#:extra-modules '()] [#:mapped-devices '()]
12498 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
12499 a list of file systems to be mounted by the initrd, possibly in addition to
12500 the root file system specified on the kernel command line via @code{--root}.
12501 @var{mapped-devices} is a list of device mappings to realize before
12502 @var{file-systems} are mounted (@pxref{Mapped Devices}).
12504 When @var{qemu-networking?} is true, set up networking with the standard QEMU
12505 parameters. When @var{virtio?} is true, load additional modules so that the
12506 initrd can be used as a QEMU guest with para-virtualized I/O drivers.
12508 When @var{volatile-root?} is true, the root file system is writable but any changes
12511 The initrd is automatically populated with all the kernel modules necessary
12512 for @var{file-systems} and for the given options. However, additional kernel
12513 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
12514 loaded at boot time in the order in which they appear.
12517 Needless to say, the initrds we produce and use embed a
12518 statically-linked Guile, and the initialization program is a Guile
12519 program. That gives a lot of flexibility. The
12520 @code{expression->initrd} procedure builds such an initrd, given the
12521 program to run in that initrd.
12523 @deffn {Monadic Procedure} expression->initrd @var{exp} @
12524 [#:guile %guile-static-stripped] [#:name "guile-initrd"]
12525 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
12526 containing @var{guile} and that evaluates @var{exp}, a G-expression,
12527 upon booting. All the derivations referenced by @var{exp} are
12528 automatically copied to the initrd.
12531 @node GRUB Configuration
12532 @subsection GRUB Configuration
12535 @cindex boot loader
12537 The operating system uses GNU@tie{}GRUB as its boot loader
12538 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
12539 configured using a @code{grub-configuration} declaration. This data type
12540 is exported by the @code{(gnu system grub)} module and described below.
12542 @deftp {Data Type} grub-configuration
12543 The type of a GRUB configuration declaration.
12547 @item @code{device}
12548 This is a string denoting the boot device. It must be a device name
12549 understood by the @command{grub-install} command, such as
12550 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
12553 @item @code{menu-entries} (default: @code{()})
12554 A possibly empty list of @code{menu-entry} objects (see below), denoting
12555 entries to appear in the GRUB boot menu, in addition to the current
12556 system entry and the entry pointing to previous system generations.
12558 @item @code{default-entry} (default: @code{0})
12559 The index of the default boot menu entry. Index 0 is for the entry of the
12562 @item @code{timeout} (default: @code{5})
12563 The number of seconds to wait for keyboard input before booting. Set to
12564 0 to boot immediately, and to -1 to wait indefinitely.
12566 @item @code{theme} (default: @var{%default-theme})
12567 The @code{grub-theme} object describing the theme to use.
12569 @item @code{grub} (default: @code{grub})
12570 The GRUB package to use.
12577 Should you want to list additional boot menu entries @i{via} the
12578 @code{menu-entries} field above, you will need to create them with the
12579 @code{menu-entry} form. For example, imagine you want to be able to
12580 boot another distro (hard to imagine!), you can define a menu entry
12585 (label "The Other Distro")
12586 (linux "/boot/old/vmlinux-2.6.32")
12587 (linux-arguments '("root=/dev/sda2"))
12588 (initrd "/boot/old/initrd"))
12593 @deftp {Data Type} menu-entry
12594 The type of an entry in the GRUB boot menu.
12599 The label to show in the menu---e.g., @code{"GNU"}.
12602 The Linux kernel image to boot, for example:
12605 (file-append linux-libre "/bzImage")
12608 It is also possible to specify a device explicitly in the file path
12609 using GRUB's device naming convention (@pxref{Naming convention,,, grub,
12610 GNU GRUB manual}), for example:
12613 "(hd0,msdos1)/boot/vmlinuz"
12616 If the device is specified explicitly as above, then the @code{device}
12617 field is ignored entirely.
12619 @item @code{linux-arguments} (default: @code{()})
12620 The list of extra Linux kernel command-line arguments---e.g.,
12621 @code{("console=ttyS0")}.
12623 @item @code{initrd}
12624 A G-Expression or string denoting the file name of the initial RAM disk
12625 to use (@pxref{G-Expressions}).
12627 @item @code{device} (default: @code{#f})
12628 The device where the kernel and initrd are to be found---i.e., the GRUB
12629 @dfn{root} for this menu entry (@pxref{root,,, grub, GNU GRUB manual}).
12631 This may be a file system label (a string), a file system UUID (a
12632 bytevector, @pxref{File Systems}), or @code{#f}, in which case GRUB will
12633 search the device containing the file specified by the @code{linux}
12634 field (@pxref{search,,, grub, GNU GRUB manual}). It must @emph{not} be
12635 an OS device name such as @file{/dev/sda1}.
12637 @item @code{device-mount-point} (default: @code{"/"})
12638 The mount point of the above device on the system. You probably do not
12639 need to change the default value. GuixSD uses it to strip the prefix of
12640 store file names for systems where @file{/gnu} or @file{/gnu/store} is
12641 on a separate partition.
12646 @c FIXME: Write documentation once it's stable.
12647 Themes are created using the @code{grub-theme} form, which is not
12650 @defvr {Scheme Variable} %default-theme
12651 This is the default GRUB theme used by the operating system, with a
12652 fancy background image displaying the GNU and Guix logos.
12656 @node Invoking guix system
12657 @subsection Invoking @code{guix system}
12659 Once you have written an operating system declaration as seen in the
12660 previous section, it can be @dfn{instantiated} using the @command{guix
12661 system} command. The synopsis is:
12664 guix system @var{options}@dots{} @var{action} @var{file}
12667 @var{file} must be the name of a file containing an
12668 @code{operating-system} declaration. @var{action} specifies how the
12669 operating system is instantiated. Currently the following values are
12674 Build the operating system described in @var{file}, activate it, and
12675 switch to it@footnote{This action (and the related actions
12676 @code{switch-generation} and @code{roll-back}) are usable only on
12677 systems already running GuixSD.}.
12679 This effects all the configuration specified in @var{file}: user
12680 accounts, system services, global package list, setuid programs, etc.
12681 The command starts system services specified in @var{file} that are not
12682 currently running; if a service is currently running, it does not
12683 attempt to upgrade it since this would not be possible without stopping it
12686 This command creates a new generation whose number is one greater than
12687 the current generation (as reported by @command{guix system
12688 list-generations}). If that generation already exists, it will be
12689 overwritten. This behavior mirrors that of @command{guix package}
12690 (@pxref{Invoking guix package}).
12692 It also adds a GRUB menu entry for the new OS configuration, and moves
12693 entries for older configurations to a submenu---unless
12694 @option{--no-grub} is passed.
12697 @c The paragraph below refers to the problem discussed at
12698 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
12699 It is highly recommended to run @command{guix pull} once before you run
12700 @command{guix system reconfigure} for the first time (@pxref{Invoking
12701 guix pull}). Failing to do that you would see an older version of Guix
12702 once @command{reconfigure} has completed.
12705 @item switch-generation
12706 @cindex generations
12707 Switch to an existing system generation. This action atomically
12708 switches the system profile to the specified system generation. It also
12709 rearranges the system's existing GRUB menu entries. It makes the menu
12710 entry for the specified system generation the default, and it moves the
12711 entries for the other generations to a submenu. The next time the
12712 system boots, it will use the specified system generation.
12714 The target generation can be specified explicitly by its generation
12715 number. For example, the following invocation would switch to system
12719 guix system switch-generation 7
12722 The target generation can also be specified relative to the current
12723 generation with the form @code{+N} or @code{-N}, where @code{+3} means
12724 ``3 generations ahead of the current generation,'' and @code{-1} means
12725 ``1 generation prior to the current generation.'' When specifying a
12726 negative value such as @code{-1}, you must precede it with @code{--} to
12727 prevent it from being parsed as an option. For example:
12730 guix system switch-generation -- -1
12733 Currently, the effect of invoking this action is @emph{only} to switch
12734 the system profile to an existing generation and rearrange the GRUB menu
12735 entries. To actually start using the target system generation, you must
12736 reboot after running this action. In the future, it will be updated to
12737 do the same things as @command{reconfigure}, like activating and
12738 deactivating services.
12740 This action will fail if the specified generation does not exist.
12743 @cindex rolling back
12744 Switch to the preceding system generation. The next time the system
12745 boots, it will use the preceding system generation. This is the inverse
12746 of @command{reconfigure}, and it is exactly the same as invoking
12747 @command{switch-generation} with an argument of @code{-1}.
12749 Currently, as with @command{switch-generation}, you must reboot after
12750 running this action to actually start using the preceding system
12754 Build the derivation of the operating system, which includes all the
12755 configuration files and programs needed to boot and run the system.
12756 This action does not actually install anything.
12759 Populate the given directory with all the files necessary to run the
12760 operating system specified in @var{file}. This is useful for first-time
12761 installations of GuixSD. For instance:
12764 guix system init my-os-config.scm /mnt
12767 copies to @file{/mnt} all the store items required by the configuration
12768 specified in @file{my-os-config.scm}. This includes configuration
12769 files, packages, and so on. It also creates other essential files
12770 needed for the system to operate correctly---e.g., the @file{/etc},
12771 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
12773 This command also installs GRUB on the device specified in
12774 @file{my-os-config}, unless the @option{--no-grub} option was passed.
12777 @cindex virtual machine
12779 @anchor{guix system vm}
12780 Build a virtual machine that contains the operating system declared in
12781 @var{file}, and return a script to run that virtual machine (VM).
12782 Arguments given to the script are passed to QEMU.
12784 The VM shares its store with the host system.
12786 Additional file systems can be shared between the host and the VM using
12787 the @code{--share} and @code{--expose} command-line options: the former
12788 specifies a directory to be shared with write access, while the latter
12789 provides read-only access to the shared directory.
12791 The example below creates a VM in which the user's home directory is
12792 accessible read-only, and where the @file{/exchange} directory is a
12793 read-write mapping of @file{$HOME/tmp} on the host:
12796 guix system vm my-config.scm \
12797 --expose=$HOME --share=$HOME/tmp=/exchange
12800 On GNU/Linux, the default is to boot directly to the kernel; this has
12801 the advantage of requiring only a very tiny root disk image since the
12802 store of the host can then be mounted.
12804 The @code{--full-boot} option forces a complete boot sequence, starting
12805 with the bootloader. This requires more disk space since a root image
12806 containing at least the kernel, initrd, and bootloader data files must
12807 be created. The @code{--image-size} option can be used to specify the
12812 Return a virtual machine or disk image of the operating system declared
12813 in @var{file} that stands alone. Use the @option{--image-size} option
12814 to specify the size of the image.
12816 When using @code{vm-image}, the returned image is in qcow2 format, which
12817 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
12818 for more information on how to run the image in a virtual machine.
12820 When using @code{disk-image}, a raw disk image is produced; it can be
12821 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
12822 the device corresponding to a USB stick, one can copy the image to it
12823 using the following command:
12826 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
12830 Return a script to run the operating system declared in @var{file}
12831 within a container. Containers are a set of lightweight isolation
12832 mechanisms provided by the kernel Linux-libre. Containers are
12833 substantially less resource-demanding than full virtual machines since
12834 the kernel, shared objects, and other resources can be shared with the
12835 host system; this also means they provide thinner isolation.
12837 Currently, the script must be run as root in order to support more than
12838 a single user and group. The container shares its store with the host
12841 As with the @code{vm} action (@pxref{guix system vm}), additional file
12842 systems to be shared between the host and container can be specified
12843 using the @option{--share} and @option{--expose} options:
12846 guix system container my-config.scm \
12847 --expose=$HOME --share=$HOME/tmp=/exchange
12851 This option requires Linux-libre 3.19 or newer.
12856 @var{options} can contain any of the common build options (@pxref{Common
12857 Build Options}). In addition, @var{options} can contain one of the
12861 @item --system=@var{system}
12862 @itemx -s @var{system}
12863 Attempt to build for @var{system} instead of the host system type.
12864 This works as per @command{guix build} (@pxref{Invoking guix build}).
12868 Return the derivation file name of the given operating system without
12871 @item --image-size=@var{size}
12872 For the @code{vm-image} and @code{disk-image} actions, create an image
12873 of the given @var{size}. @var{size} may be a number of bytes, or it may
12874 include a unit as a suffix (@pxref{Block size, size specifications,,
12875 coreutils, GNU Coreutils}).
12877 @item --on-error=@var{strategy}
12878 Apply @var{strategy} when an error occurs when reading @var{file}.
12879 @var{strategy} may be one of the following:
12882 @item nothing-special
12883 Report the error concisely and exit. This is the default strategy.
12886 Likewise, but also display a backtrace.
12889 Report the error and enter Guile's debugger. From there, you can run
12890 commands such as @code{,bt} to get a backtrace, @code{,locals} to
12891 display local variable values, and more generally inspect the state of the
12892 program. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
12893 a list of available debugging commands.
12898 All the actions above, except @code{build} and @code{init},
12899 can use KVM support in the Linux-libre kernel. Specifically, if the
12900 machine has hardware virtualization support, the corresponding
12901 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
12902 must exist and be readable and writable by the user and by the
12903 build users of the daemon (@pxref{Build Environment Setup}).
12906 Once you have built, configured, re-configured, and re-re-configured
12907 your GuixSD installation, you may find it useful to list the operating
12908 system generations available on disk---and that you can choose from the
12913 @item list-generations
12914 List a summary of each generation of the operating system available on
12915 disk, in a human-readable way. This is similar to the
12916 @option{--list-generations} option of @command{guix package}
12917 (@pxref{Invoking guix package}).
12919 Optionally, one can specify a pattern, with the same syntax that is used
12920 in @command{guix package --list-generations}, to restrict the list of
12921 generations displayed. For instance, the following command displays
12922 generations that are up to 10 days old:
12925 $ guix system list-generations 10d
12930 The @command{guix system} command has even more to offer! The following
12931 sub-commands allow you to visualize how your system services relate to
12934 @anchor{system-extension-graph}
12937 @item extension-graph
12938 Emit in Dot/Graphviz format to standard output the @dfn{service
12939 extension graph} of the operating system defined in @var{file}
12940 (@pxref{Service Composition}, for more information on service
12946 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
12949 produces a PDF file showing the extension relations among services.
12951 @anchor{system-shepherd-graph}
12952 @item shepherd-graph
12953 Emit in Dot/Graphviz format to standard output the @dfn{dependency
12954 graph} of shepherd services of the operating system defined in
12955 @var{file}. @xref{Shepherd Services}, for more information and for an
12960 @node Running GuixSD in a VM
12961 @subsection Running GuixSD in a Virtual Machine
12963 @cindex virtual machine
12964 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
12965 virtual machine image using @command{guix system vm-image}
12966 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
12967 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
12970 To run the image in QEMU, copy it out of the store (@pxref{The Store})
12971 and give yourself permission to write to the copy. When invoking QEMU,
12972 you must choose a system emulator that is suitable for your hardware
12973 platform. Here is a minimal QEMU invocation that will boot the result
12974 of @command{guix system vm-image} on x86_64 hardware:
12977 $ qemu-system-x86_64 \
12978 -net user -net nic,model=virtio \
12979 -enable-kvm -m 256 /tmp/qemu-image
12982 Here is what each of these options means:
12985 @item qemu-system-x86_64
12986 This specifies the hardware platform to emulate. This should match the
12990 Enable the unprivileged user-mode network stack. The guest OS can
12991 access the host but not vice versa. This is the simplest way to get the
12994 @item -net nic,model=virtio
12995 You must create a network interface of a given model. If you do not
12996 create a NIC, the boot will fail. Assuming your hardware platform is
12997 x86_64, you can get a list of available NIC models by running
12998 @command{qemu-system-x86_64 -net nic,model=help}.
13001 If your system has hardware virtualization extensions, enabling the
13002 virtual machine support (KVM) of the Linux kernel will make things run
13006 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
13007 which may be insufficient for some operations.
13009 @item /tmp/qemu-image
13010 The file name of the qcow2 image.
13013 The default @command{run-vm.sh} script that is returned by an invokation of
13014 @command{guix system vm} does not add a @command{-net user} flag by default.
13015 To get network access from within the vm add the @code{(dhcp-client-service)}
13016 to your system definition and start the VM using
13017 @command{`guix system vm config.scm` -net user}. An important caveat of using
13018 @command{-net user} for networking is that @command{ping} will not work, because
13019 it uses the ICMP protocol. You'll have to use a different command to check for
13020 network connectivity, like for example @command{curl}.
13022 @subsubsection Connecting Through SSH
13026 To enable SSH inside a VM you need to add a SSH server like @code{(dropbear-service)}
13027 or @code{(lsh-service)} to your VM. The @code{(lsh-service}) doesn't currently
13028 boot unsupervised. It requires you to type some characters to initialize the
13029 randomness generator. In addition you need to forward the SSH port, 22 by
13030 default, to the host. You can do this with
13033 `guix system vm config.scm` -net user,hostfwd=tcp::10022-:22
13036 To connect to the VM you can run
13039 ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -p 10022
13042 The @command{-p} tells @command{ssh} the port you want to connect to.
13043 @command{-o UserKnownHostsFile=/dev/null} prevents @command{ssh} from complaining
13044 every time you modify your @command{config.scm} file and the
13045 @command{-o StrictHostKeyChecking=no} prevents you from having to allow a
13046 connection to an unknown host every time you connect.
13048 @subsubsection Using @command{virt-viewer} with Spice
13050 As an alternative to the default @command{qemu} graphical client you can
13051 use the @command{remote-viewer} from the @command{virt-viewer} package. To
13052 connect pass the @command{-spice port=5930,disable-ticketing} flag to
13053 @command{qemu}. See previous section for further information on how to do this.
13055 Spice also allows you to do some nice stuff like share your clipboard with your
13056 VM. To enable that you'll also have to pass the following flags to @command{qemu}:
13059 -device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0,addr=0x5
13060 -chardev spicevmc,name=vdagent,id=vdagent
13061 -device virtserialport,nr=1,bus=virtio-serial0.0,chardev=vdagent,
13062 name=com.redhat.spice.0
13065 You'll also need to add the @pxref{Miscellaneous Services, Spice service}.
13067 @node Defining Services
13068 @subsection Defining Services
13070 The previous sections show the available services and how one can combine
13071 them in an @code{operating-system} declaration. But how do we define
13072 them in the first place? And what is a service anyway?
13075 * Service Composition:: The model for composing services.
13076 * Service Types and Services:: Types and services.
13077 * Service Reference:: API reference.
13078 * Shepherd Services:: A particular type of service.
13081 @node Service Composition
13082 @subsubsection Service Composition
13086 Here we define a @dfn{service} as, broadly, something that extends the
13087 functionality of the operating system. Often a service is a process---a
13088 @dfn{daemon}---started when the system boots: a secure shell server, a
13089 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
13090 whose execution can be triggered by another daemon---e.g., an FTP server
13091 started by @command{inetd} or a D-Bus service activated by
13092 @command{dbus-daemon}. Occasionally, a service does not map to a
13093 daemon. For instance, the ``account'' service collects user accounts
13094 and makes sure they exist when the system runs; the ``udev'' service
13095 collects device management rules and makes them available to the eudev
13096 daemon; the @file{/etc} service populates the @file{/etc} directory
13099 @cindex service extensions
13100 GuixSD services are connected by @dfn{extensions}. For instance, the
13101 secure shell service @emph{extends} the Shepherd---the GuixSD
13102 initialization system, running as PID@tie{}1---by giving it the command
13103 lines to start and stop the secure shell daemon (@pxref{Networking
13104 Services, @code{lsh-service}}); the UPower service extends the D-Bus
13105 service by passing it its @file{.service} specification, and extends the
13106 udev service by passing it device management rules (@pxref{Desktop
13107 Services, @code{upower-service}}); the Guix daemon service extends the
13108 Shepherd by passing it the command lines to start and stop the daemon,
13109 and extends the account service by passing it a list of required build
13110 user accounts (@pxref{Base Services}).
13112 All in all, services and their ``extends'' relations form a directed
13113 acyclic graph (DAG). If we represent services as boxes and extensions
13114 as arrows, a typical system might provide something like this:
13116 @image{images/service-graph,,5in,Typical service extension graph.}
13118 @cindex system service
13119 At the bottom, we see the @dfn{system service}, which produces the
13120 directory containing everything to run and boot the system, as returned
13121 by the @command{guix system build} command. @xref{Service Reference},
13122 to learn about the other service types shown here.
13123 @xref{system-extension-graph, the @command{guix system extension-graph}
13124 command}, for information on how to generate this representation for a
13125 particular operating system definition.
13127 @cindex service types
13128 Technically, developers can define @dfn{service types} to express these
13129 relations. There can be any number of services of a given type on the
13130 system---for instance, a system running two instances of the GNU secure
13131 shell server (lsh) has two instances of @var{lsh-service-type}, with
13132 different parameters.
13134 The following section describes the programming interface for service
13135 types and services.
13137 @node Service Types and Services
13138 @subsubsection Service Types and Services
13140 A @dfn{service type} is a node in the DAG described above. Let us start
13141 with a simple example, the service type for the Guix build daemon
13142 (@pxref{Invoking guix-daemon}):
13145 (define guix-service-type
13149 (list (service-extension shepherd-root-service-type guix-shepherd-service)
13150 (service-extension account-service-type guix-accounts)
13151 (service-extension activation-service-type guix-activation)))))
13155 It defines two things:
13159 A name, whose sole purpose is to make inspection and debugging easier.
13162 A list of @dfn{service extensions}, where each extension designates the
13163 target service type and a procedure that, given the parameters of the
13164 service, returns a list of objects to extend the service of that type.
13166 Every service type has at least one service extension. The only
13167 exception is the @dfn{boot service type}, which is the ultimate service.
13170 In this example, @var{guix-service-type} extends three services:
13173 @item shepherd-root-service-type
13174 The @var{guix-shepherd-service} procedure defines how the Shepherd
13175 service is extended. Namely, it returns a @code{<shepherd-service>}
13176 object that defines how @command{guix-daemon} is started and stopped
13177 (@pxref{Shepherd Services}).
13179 @item account-service-type
13180 This extension for this service is computed by @var{guix-accounts},
13181 which returns a list of @code{user-group} and @code{user-account}
13182 objects representing the build user accounts (@pxref{Invoking
13185 @item activation-service-type
13186 Here @var{guix-activation} is a procedure that returns a gexp, which is
13187 a code snippet to run at ``activation time''---e.g., when the service is
13191 A service of this type is instantiated like this:
13194 (service guix-service-type
13195 (guix-configuration
13197 (use-substitutes? #f)))
13200 The second argument to the @code{service} form is a value representing
13201 the parameters of this specific service instance.
13202 @xref{guix-configuration-type, @code{guix-configuration}}, for
13203 information about the @code{guix-configuration} data type.
13205 @var{guix-service-type} is quite simple because it extends other
13206 services but is not extensible itself.
13208 @c @subsubsubsection Extensible Service Types
13210 The service type for an @emph{extensible} service looks like this:
13213 (define udev-service-type
13214 (service-type (name 'udev)
13216 (list (service-extension shepherd-root-service-type
13217 udev-shepherd-service)))
13219 (compose concatenate) ;concatenate the list of rules
13220 (extend (lambda (config rules)
13222 (($ <udev-configuration> udev initial-rules)
13223 (udev-configuration
13224 (udev udev) ;the udev package to use
13225 (rules (append initial-rules rules)))))))))
13228 This is the service type for the
13229 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
13230 management daemon}. Compared to the previous example, in addition to an
13231 extension of @var{shepherd-root-service-type}, we see two new fields:
13235 This is the procedure to @dfn{compose} the list of extensions to
13236 services of this type.
13238 Services can extend the udev service by passing it lists of rules; we
13239 compose those extensions simply by concatenating them.
13242 This procedure defines how the value of the service is @dfn{extended} with
13243 the composition of the extensions.
13245 Udev extensions are composed into a list of rules, but the udev service
13246 value is itself a @code{<udev-configuration>} record. So here, we
13247 extend that record by appending the list of rules it contains to the
13248 list of contributed rules.
13251 There can be only one instance of an extensible service type such as
13252 @var{udev-service-type}. If there were more, the
13253 @code{service-extension} specifications would be ambiguous.
13255 Still here? The next section provides a reference of the programming
13256 interface for services.
13258 @node Service Reference
13259 @subsubsection Service Reference
13261 We have seen an overview of service types (@pxref{Service Types and
13262 Services}). This section provides a reference on how to manipulate
13263 services and service types. This interface is provided by the
13264 @code{(gnu services)} module.
13266 @deffn {Scheme Procedure} service @var{type} @var{value}
13267 Return a new service of @var{type}, a @code{<service-type>} object (see
13268 below.) @var{value} can be any object; it represents the parameters of
13269 this particular service instance.
13272 @deffn {Scheme Procedure} service? @var{obj}
13273 Return true if @var{obj} is a service.
13276 @deffn {Scheme Procedure} service-kind @var{service}
13277 Return the type of @var{service}---i.e., a @code{<service-type>} object.
13280 @deffn {Scheme Procedure} service-parameters @var{service}
13281 Return the value associated with @var{service}. It represents its
13285 Here is an example of how a service is created and manipulated:
13289 (service nginx-service-type
13290 (nginx-configuration
13292 (log-directory log-directory)
13293 (run-directory run-directory)
13294 (file config-file))))
13299 (eq? (service-kind s) nginx-service-type)
13303 The @code{modify-services} form provides a handy way to change the
13304 parameters of some of the services of a list such as
13305 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). It
13306 evaluates to a list of services. Of course, you could always use
13307 standard list combinators such as @code{map} and @code{fold} to do that
13308 (@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual});
13309 @code{modify-services} simply provides a more concise form for this
13312 @deffn {Scheme Syntax} modify-services @var{services} @
13313 (@var{type} @var{variable} => @var{body}) @dots{}
13315 Modify the services listed in @var{services} according to the given
13316 clauses. Each clause has the form:
13319 (@var{type} @var{variable} => @var{body})
13322 where @var{type} is a service type---e.g.,
13323 @code{guix-service-type}---and @var{variable} is an identifier that is
13324 bound within the @var{body} to the service parameters---e.g., a
13325 @code{guix-configuration} instance---of the original service of that
13328 The @var{body} should evaluate to the new service parameters, which will
13329 be used to configure the new service. This new service will replace the
13330 original in the resulting list. Because a service's service parameters
13331 are created using @code{define-record-type*}, you can write a succinct
13332 @var{body} that evaluates to the new service parameters by using the
13333 @code{inherit} feature that @code{define-record-type*} provides.
13335 @xref{Using the Configuration System}, for example usage.
13339 Next comes the programming interface for service types. This is
13340 something you want to know when writing new service definitions, but not
13341 necessarily when simply looking for ways to customize your
13342 @code{operating-system} declaration.
13344 @deftp {Data Type} service-type
13345 @cindex service type
13346 This is the representation of a @dfn{service type} (@pxref{Service Types
13351 This is a symbol, used only to simplify inspection and debugging.
13353 @item @code{extensions}
13354 A non-empty list of @code{<service-extension>} objects (see below).
13356 @item @code{compose} (default: @code{#f})
13357 If this is @code{#f}, then the service type denotes services that cannot
13358 be extended---i.e., services that do not receive ``values'' from other
13361 Otherwise, it must be a one-argument procedure. The procedure is called
13362 by @code{fold-services} and is passed a list of values collected from
13363 extensions. It must return a value that is a valid parameter value for
13364 the service instance.
13366 @item @code{extend} (default: @code{#f})
13367 If this is @code{#f}, services of this type cannot be extended.
13369 Otherwise, it must be a two-argument procedure: @code{fold-services}
13370 calls it, passing it the initial value of the service as the first argument
13371 and the result of applying @code{compose} to the extension values as the
13375 @xref{Service Types and Services}, for examples.
13378 @deffn {Scheme Procedure} service-extension @var{target-type} @
13380 Return a new extension for services of type @var{target-type}.
13381 @var{compute} must be a one-argument procedure: @code{fold-services}
13382 calls it, passing it the value associated with the service that provides
13383 the extension; it must return a valid value for the target service.
13386 @deffn {Scheme Procedure} service-extension? @var{obj}
13387 Return true if @var{obj} is a service extension.
13390 Occasionally, you might want to simply extend an existing service. This
13391 involves creating a new service type and specifying the extension of
13392 interest, which can be verbose; the @code{simple-service} procedure
13393 provides a shorthand for this.
13395 @deffn {Scheme Procedure} simple-service @var{name} @var{target} @var{value}
13396 Return a service that extends @var{target} with @var{value}. This works
13397 by creating a singleton service type @var{name}, of which the returned
13398 service is an instance.
13400 For example, this extends mcron (@pxref{Scheduled Job Execution}) with
13404 (simple-service 'my-mcron-job mcron-service-type
13405 #~(job '(next-hour (3)) "guix gc -F 2G"))
13409 At the core of the service abstraction lies the @code{fold-services}
13410 procedure, which is responsible for ``compiling'' a list of services
13411 down to a single directory that contains everything needed to boot and
13412 run the system---the directory shown by the @command{guix system build}
13413 command (@pxref{Invoking guix system}). In essence, it propagates
13414 service extensions down the service graph, updating each node parameters
13415 on the way, until it reaches the root node.
13417 @deffn {Scheme Procedure} fold-services @var{services} @
13418 [#:target-type @var{system-service-type}]
13419 Fold @var{services} by propagating their extensions down to the root of
13420 type @var{target-type}; return the root service adjusted accordingly.
13423 Lastly, the @code{(gnu services)} module also defines several essential
13424 service types, some of which are listed below.
13426 @defvr {Scheme Variable} system-service-type
13427 This is the root of the service graph. It produces the system directory
13428 as returned by the @command{guix system build} command.
13431 @defvr {Scheme Variable} boot-service-type
13432 The type of the ``boot service'', which produces the @dfn{boot script}.
13433 The boot script is what the initial RAM disk runs when booting.
13436 @defvr {Scheme Variable} etc-service-type
13437 The type of the @file{/etc} service. This service can be extended by
13438 passing it name/file tuples such as:
13441 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
13444 In this example, the effect would be to add an @file{/etc/issue} file
13445 pointing to the given file.
13448 @defvr {Scheme Variable} setuid-program-service-type
13449 Type for the ``setuid-program service''. This service collects lists of
13450 executable file names, passed as gexps, and adds them to the set of
13451 setuid-root programs on the system (@pxref{Setuid Programs}).
13454 @defvr {Scheme Variable} profile-service-type
13455 Type of the service that populates the @dfn{system profile}---i.e., the
13456 programs under @file{/run/current-system/profile}. Other services can
13457 extend it by passing it lists of packages to add to the system profile.
13461 @node Shepherd Services
13462 @subsubsection Shepherd Services
13464 @cindex shepherd services
13466 @cindex init system
13467 The @code{(gnu services shepherd)} module provides a way to define
13468 services managed by the GNU@tie{}Shepherd, which is the GuixSD
13469 initialization system---the first process that is started when the
13470 system boots, also known as PID@tie{}1
13471 (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}).
13473 Services in the Shepherd can depend on each other. For instance, the
13474 SSH daemon may need to be started after the syslog daemon has been
13475 started, which in turn can only happen once all the file systems have
13476 been mounted. The simple operating system defined earlier (@pxref{Using
13477 the Configuration System}) results in a service graph like this:
13479 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
13481 You can actually generate such a graph for any operating system
13482 definition using the @command{guix system shepherd-graph} command
13483 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
13485 The @var{%shepherd-root-service} is a service object representing
13486 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
13487 by passing it lists of @code{<shepherd-service>} objects.
13489 @deftp {Data Type} shepherd-service
13490 The data type representing a service managed by the Shepherd.
13493 @item @code{provision}
13494 This is a list of symbols denoting what the service provides.
13496 These are the names that may be passed to @command{herd start},
13497 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
13498 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
13499 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
13501 @item @code{requirements} (default: @code{'()})
13502 List of symbols denoting the Shepherd services this one depends on.
13504 @item @code{respawn?} (default: @code{#t})
13505 Whether to restart the service when it stops, for instance when the
13506 underlying process dies.
13509 @itemx @code{stop} (default: @code{#~(const #f)})
13510 The @code{start} and @code{stop} fields refer to the Shepherd's
13511 facilities to start and stop processes (@pxref{Service De- and
13512 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
13513 G-expressions that get expanded in the Shepherd configuration file
13514 (@pxref{G-Expressions}).
13516 @item @code{documentation}
13517 A documentation string, as shown when running:
13520 herd doc @var{service-name}
13523 where @var{service-name} is one of the symbols in @var{provision}
13524 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
13526 @item @code{modules} (default: @var{%default-modules})
13527 This is the list of modules that must be in scope when @code{start} and
13528 @code{stop} are evaluated.
13533 @defvr {Scheme Variable} shepherd-root-service-type
13534 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
13536 This is the service type that extensions target when they want to create
13537 shepherd services (@pxref{Service Types and Services}, for an example).
13538 Each extension must pass a list of @code{<shepherd-service>}.
13541 @defvr {Scheme Variable} %shepherd-root-service
13542 This service represents PID@tie{}1.
13546 @node Installing Debugging Files
13547 @section Installing Debugging Files
13549 @cindex debugging files
13550 Program binaries, as produced by the GCC compilers for instance, are
13551 typically written in the ELF format, with a section containing
13552 @dfn{debugging information}. Debugging information is what allows the
13553 debugger, GDB, to map binary code to source code; it is required to
13554 debug a compiled program in good conditions.
13556 The problem with debugging information is that is takes up a fair amount
13557 of disk space. For example, debugging information for the GNU C Library
13558 weighs in at more than 60 MiB. Thus, as a user, keeping all the
13559 debugging info of all the installed programs is usually not an option.
13560 Yet, space savings should not come at the cost of an impediment to
13561 debugging---especially in the GNU system, which should make it easier
13562 for users to exert their computing freedom (@pxref{GNU Distribution}).
13564 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
13565 mechanism that allows users to get the best of both worlds: debugging
13566 information can be stripped from the binaries and stored in separate
13567 files. GDB is then able to load debugging information from those files,
13568 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
13571 The GNU distribution takes advantage of this by storing debugging
13572 information in the @code{lib/debug} sub-directory of a separate package
13573 output unimaginatively called @code{debug} (@pxref{Packages with
13574 Multiple Outputs}). Users can choose to install the @code{debug} output
13575 of a package when they need it. For instance, the following command
13576 installs the debugging information for the GNU C Library and for GNU
13580 guix package -i glibc:debug guile:debug
13583 GDB must then be told to look for debug files in the user's profile, by
13584 setting the @code{debug-file-directory} variable (consider setting it
13585 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
13589 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
13592 From there on, GDB will pick up debugging information from the
13593 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
13595 In addition, you will most likely want GDB to be able to show the source
13596 code being debugged. To do that, you will have to unpack the source
13597 code of the package of interest (obtained with @code{guix build
13598 --source}, @pxref{Invoking guix build}), and to point GDB to that source
13599 directory using the @code{directory} command (@pxref{Source Path,
13600 @code{directory},, gdb, Debugging with GDB}).
13602 @c XXX: keep me up-to-date
13603 The @code{debug} output mechanism in Guix is implemented by the
13604 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
13605 opt-in---debugging information is available only for the packages
13606 with definitions explicitly declaring a @code{debug} output. This may be
13607 changed to opt-out in the future if our build farm servers can handle
13608 the load. To check whether a package has a @code{debug} output, use
13609 @command{guix package --list-available} (@pxref{Invoking guix package}).
13612 @node Security Updates
13613 @section Security Updates
13615 @cindex security updates
13616 @cindex security vulnerabilities
13617 Occasionally, important security vulnerabilities are discovered in software
13618 packages and must be patched. Guix developers try hard to keep track of
13619 known vulnerabilities and to apply fixes as soon as possible in the
13620 @code{master} branch of Guix (we do not yet provide a ``stable'' branch
13621 containing only security updates.) The @command{guix lint} tool helps
13622 developers find out about vulnerable versions of software packages in the
13627 gnu/packages/base.scm:652:2: glibc-2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547
13628 gnu/packages/gcc.scm:334:2: gcc-4.9.3: probably vulnerable to CVE-2015-5276
13629 gnu/packages/image.scm:312:2: openjpeg-2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924
13633 @xref{Invoking guix lint}, for more information.
13636 As of version @value{VERSION}, the feature described below is considered
13640 Guix follows a functional
13641 package management discipline (@pxref{Introduction}), which implies
13642 that, when a package is changed, @emph{every package that depends on it}
13643 must be rebuilt. This can significantly slow down the deployment of
13644 fixes in core packages such as libc or Bash, since basically the whole
13645 distribution would need to be rebuilt. Using pre-built binaries helps
13646 (@pxref{Substitutes}), but deployment may still take more time than
13650 To address this, Guix implements @dfn{grafts}, a mechanism that allows
13651 for fast deployment of critical updates without the costs associated
13652 with a whole-distribution rebuild. The idea is to rebuild only the
13653 package that needs to be patched, and then to ``graft'' it onto packages
13654 explicitly installed by the user and that were previously referring to
13655 the original package. The cost of grafting is typically very low, and
13656 order of magnitudes lower than a full rebuild of the dependency chain.
13658 @cindex replacements of packages, for grafts
13659 For instance, suppose a security update needs to be applied to Bash.
13660 Guix developers will provide a package definition for the ``fixed''
13661 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
13662 Packages}). Then, the original package definition is augmented with a
13663 @code{replacement} field pointing to the package containing the bug fix:
13670 (replacement bash-fixed)))
13673 From there on, any package depending directly or indirectly on Bash---as
13674 reported by @command{guix gc --requisites} (@pxref{Invoking guix
13675 gc})---that is installed is automatically ``rewritten'' to refer to
13676 @var{bash-fixed} instead of @var{bash}. This grafting process takes
13677 time proportional to the size of the package, usually less than a
13678 minute for an ``average'' package on a recent machine. Grafting is
13679 recursive: when an indirect dependency requires grafting, then grafting
13680 ``propagates'' up to the package that the user is installing.
13682 Currently, the length of the name and version of the graft and that of
13683 the package it replaces (@var{bash-fixed} and @var{bash} in the example
13684 above) must be equal. This restriction mostly comes from the fact that
13685 grafting works by patching files, including binary files, directly.
13686 Other restrictions may apply: for instance, when adding a graft to a
13687 package providing a shared library, the original shared library and its
13688 replacement must have the same @code{SONAME} and be binary-compatible.
13690 The @option{--no-grafts} command-line option allows you to forcefully
13691 avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}).
13695 guix build bash --no-grafts
13699 returns the store file name of the original Bash, whereas:
13706 returns the store file name of the ``fixed'', replacement Bash. This
13707 allows you to distinguish between the two variants of Bash.
13709 To verify which Bash your whole profile refers to, you can run
13710 (@pxref{Invoking guix gc}):
13713 guix gc -R `readlink -f ~/.guix-profile` | grep bash
13717 @dots{} and compare the store file names that you get with those above.
13718 Likewise for a complete GuixSD system generation:
13721 guix gc -R `guix system build my-config.scm` | grep bash
13724 Lastly, to check which Bash running processes are using, you can use the
13725 @command{lsof} command:
13728 lsof | grep /gnu/store/.*bash
13732 @node Package Modules
13733 @section Package Modules
13735 From a programming viewpoint, the package definitions of the
13736 GNU distribution are provided by Guile modules in the @code{(gnu packages
13737 @dots{})} name space@footnote{Note that packages under the @code{(gnu
13738 packages @dots{})} module name space are not necessarily ``GNU
13739 packages''. This module naming scheme follows the usual Guile module
13740 naming convention: @code{gnu} means that these modules are distributed
13741 as part of the GNU system, and @code{packages} identifies modules that
13742 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
13743 Reference Manual}). For instance, the @code{(gnu packages emacs)}
13744 module exports a variable named @code{emacs}, which is bound to a
13745 @code{<package>} object (@pxref{Defining Packages}).
13747 The @code{(gnu packages @dots{})} module name space is
13748 automatically scanned for packages by the command-line tools. For
13749 instance, when running @code{guix package -i emacs}, all the @code{(gnu
13750 packages @dots{})} modules are scanned until one that exports a package
13751 object whose name is @code{emacs} is found. This package search
13752 facility is implemented in the @code{(gnu packages)} module.
13754 @cindex customization, of packages
13755 @cindex package module search path
13756 Users can store package definitions in modules with different
13757 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
13758 name and module name must match. For instance, the @code{(my-packages
13759 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
13760 relative to the load path specified with @option{--load-path} or
13761 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
13762 guile, GNU Guile Reference Manual}, for details.}. These package definitions
13763 will not be visible by default. Users can invoke commands such as
13764 @command{guix package} and @command{guix build} with the
13765 @code{-e} option so that they know where to find the package. Better
13766 yet, they can use the
13767 @code{-L} option of these commands to make those modules visible
13768 (@pxref{Invoking guix build, @code{--load-path}}), or define the
13769 @code{GUIX_PACKAGE_PATH} environment variable. This environment
13770 variable makes it easy to extend or customize the distribution and is
13771 honored by all the user interfaces.
13773 @defvr {Environment Variable} GUIX_PACKAGE_PATH
13774 This is a colon-separated list of directories to search for additional
13775 package modules. Directories listed in this variable take precedence
13776 over the own modules of the distribution.
13779 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
13780 each package is built based solely on other packages in the
13781 distribution. The root of this dependency graph is a small set of
13782 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
13783 bootstrap)} module. For more information on bootstrapping,
13784 @pxref{Bootstrapping}.
13786 @node Packaging Guidelines
13787 @section Packaging Guidelines
13789 @cindex packages, creating
13790 The GNU distribution is nascent and may well lack some of your favorite
13791 packages. This section describes how you can help make the distribution
13792 grow. @xref{Contributing}, for additional information on how you can
13795 Free software packages are usually distributed in the form of
13796 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
13797 all the source files. Adding a package to the distribution means
13798 essentially two things: adding a @dfn{recipe} that describes how to
13799 build the package, including a list of other packages required to build
13800 it, and adding @dfn{package metadata} along with that recipe, such as a
13801 description and licensing information.
13803 In Guix all this information is embodied in @dfn{package definitions}.
13804 Package definitions provide a high-level view of the package. They are
13805 written using the syntax of the Scheme programming language; in fact,
13806 for each package we define a variable bound to the package definition,
13807 and export that variable from a module (@pxref{Package Modules}).
13808 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
13809 creating packages. For more information on package definitions,
13810 @pxref{Defining Packages}.
13812 Once a package definition is in place, stored in a file in the Guix
13813 source tree, it can be tested using the @command{guix build} command
13814 (@pxref{Invoking guix build}). For example, assuming the new package is
13815 called @code{gnew}, you may run this command from the Guix build tree
13816 (@pxref{Running Guix Before It Is Installed}):
13819 ./pre-inst-env guix build gnew --keep-failed
13822 Using @code{--keep-failed} makes it easier to debug build failures since
13823 it provides access to the failed build tree. Another useful
13824 command-line option when debugging is @code{--log-file}, to access the
13827 If the package is unknown to the @command{guix} command, it may be that
13828 the source file contains a syntax error, or lacks a @code{define-public}
13829 clause to export the package variable. To figure it out, you may load
13830 the module from Guile to get more information about the actual error:
13833 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
13836 Once your package builds correctly, please send us a patch
13837 (@pxref{Contributing}). Well, if you need help, we will be happy to
13838 help you too. Once the patch is committed in the Guix repository, the
13839 new package automatically gets built on the supported platforms by
13840 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
13843 @cindex substituter
13844 Users can obtain the new package definition simply by running
13845 @command{guix pull} (@pxref{Invoking guix pull}). When
13846 @code{hydra.gnu.org} is done building the package, installing the
13847 package automatically downloads binaries from there
13848 (@pxref{Substitutes}). The only place where human intervention is
13849 needed is to review and apply the patch.
13853 * Software Freedom:: What may go into the distribution.
13854 * Package Naming:: What's in a name?
13855 * Version Numbers:: When the name is not enough.
13856 * Synopses and Descriptions:: Helping users find the right package.
13857 * Python Modules:: Taming the snake.
13858 * Perl Modules:: Little pearls.
13859 * Java Packages:: Coffee break.
13860 * Fonts:: Fond of fonts.
13863 @node Software Freedom
13864 @subsection Software Freedom
13866 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
13867 @cindex free software
13868 The GNU operating system has been developed so that users can have
13869 freedom in their computing. GNU is @dfn{free software}, meaning that
13870 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
13871 essential freedoms}: to run the program, to study and change the program
13872 in source code form, to redistribute exact copies, and to distribute
13873 modified versions. Packages found in the GNU distribution provide only
13874 software that conveys these four freedoms.
13876 In addition, the GNU distribution follow the
13877 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
13878 software distribution guidelines}. Among other things, these guidelines
13879 reject non-free firmware, recommendations of non-free software, and
13880 discuss ways to deal with trademarks and patents.
13882 Some otherwise free upstream package sources contain a small and optional
13883 subset that violates the above guidelines, for instance because this subset
13884 is itself non-free code. When that happens, the offending items are removed
13885 with appropriate patches or code snippets in the @code{origin} form of the
13886 package (@pxref{Defining Packages}). This way, @code{guix
13887 build --source} returns the ``freed'' source rather than the unmodified
13891 @node Package Naming
13892 @subsection Package Naming
13894 @cindex package name
13895 A package has actually two names associated with it:
13896 First, there is the name of the @emph{Scheme variable}, the one following
13897 @code{define-public}. By this name, the package can be made known in the
13898 Scheme code, for instance as input to another package. Second, there is
13899 the string in the @code{name} field of a package definition. This name
13900 is used by package management commands such as
13901 @command{guix package} and @command{guix build}.
13903 Both are usually the same and correspond to the lowercase conversion of
13904 the project name chosen upstream, with underscores replaced with
13905 hyphens. For instance, GNUnet is available as @code{gnunet}, and
13906 SDL_net as @code{sdl-net}.
13908 We do not add @code{lib} prefixes for library packages, unless these are
13909 already part of the official project name. But @pxref{Python
13910 Modules} and @ref{Perl Modules} for special rules concerning modules for
13911 the Python and Perl languages.
13913 Font package names are handled differently, @pxref{Fonts}.
13916 @node Version Numbers
13917 @subsection Version Numbers
13919 @cindex package version
13920 We usually package only the latest version of a given free software
13921 project. But sometimes, for instance for incompatible library versions,
13922 two (or more) versions of the same package are needed. These require
13923 different Scheme variable names. We use the name as defined
13924 in @ref{Package Naming}
13925 for the most recent version; previous versions use the same name, suffixed
13926 by @code{-} and the smallest prefix of the version number that may
13927 distinguish the two versions.
13929 The name inside the package definition is the same for all versions of a
13930 package and does not contain any version number.
13932 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
13935 (define-public gtk+
13940 (define-public gtk+-2
13943 (version "2.24.20")
13946 If we also wanted GTK+ 3.8.2, this would be packaged as
13948 (define-public gtk+-3.8
13955 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
13956 @c for a discussion of what follows.
13957 @cindex version number, for VCS snapshots
13958 Occasionally, we package snapshots of upstream's version control system
13959 (VCS) instead of formal releases. This should remain exceptional,
13960 because it is up to upstream developers to clarify what the stable
13961 release is. Yet, it is sometimes necessary. So, what should we put in
13962 the @code{version} field?
13964 Clearly, we need to make the commit identifier of the VCS snapshot
13965 visible in the version string, but we also need to make sure that the
13966 version string is monotonically increasing so that @command{guix package
13967 --upgrade} can determine which version is newer. Since commit
13968 identifiers, notably with Git, are not monotonically increasing, we add
13969 a revision number that we increase each time we upgrade to a newer
13970 snapshot. The resulting version string looks like this:
13975 | | `-- upstream commit ID
13977 | `--- Guix package revision
13979 latest upstream version
13982 It is a good idea to strip commit identifiers in the @code{version}
13983 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
13984 aesthetics have a role to play here) as well as problems related to OS
13985 limits such as the maximum shebang length (127 bytes for the Linux
13986 kernel.) It is best to use the full commit identifiers in
13987 @code{origin}s, though, to avoid ambiguities. A typical package
13988 definition may look like this:
13992 (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
13993 (revision "1")) ;Guix package revision
13995 (version (string-append "0.9-" revision "."
13996 (string-take commit 7)))
13999 (uri (git-reference
14000 (url "git://example.org/my-package.git")
14002 (sha256 (base32 "1mbikn@dots{}"))
14003 (file-name (string-append "my-package-" version
14009 @node Synopses and Descriptions
14010 @subsection Synopses and Descriptions
14012 @cindex package description
14013 @cindex package synopsis
14014 As we have seen before, each package in GNU@tie{}Guix includes a
14015 synopsis and a description (@pxref{Defining Packages}). Synopses and
14016 descriptions are important: They are what @command{guix package
14017 --search} searches, and a crucial piece of information to help users
14018 determine whether a given package suits their needs. Consequently,
14019 packagers should pay attention to what goes into them.
14021 Synopses must start with a capital letter and must not end with a
14022 period. They must not start with ``a'' or ``the'', which usually does
14023 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
14024 tool that frobs files''. The synopsis should say what the package
14025 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
14026 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
14027 matching a pattern''.
14029 Keep in mind that the synopsis must be meaningful for a very wide
14030 audience. For example, ``Manipulate alignments in the SAM format''
14031 might make sense for a seasoned bioinformatics researcher, but might be
14032 fairly unhelpful or even misleading to a non-specialized audience. It
14033 is a good idea to come up with a synopsis that gives an idea of the
14034 application domain of the package. In this example, this might give
14035 something like ``Manipulate nucleotide sequence alignments'', which
14036 hopefully gives the user a better idea of whether this is what they are
14039 Descriptions should take between five and ten lines. Use full
14040 sentences, and avoid using acronyms without first introducing them.
14041 Please avoid marketing phrases such as ``world-leading'',
14042 ``industrial-strength'', and ``next-generation'', and avoid superlatives
14043 like ``the most advanced''---they are not helpful to users looking for a
14044 package and may even sound suspicious. Instead, try to be factual,
14045 mentioning use cases and features.
14047 @cindex Texinfo markup, in package descriptions
14048 Descriptions can include Texinfo markup, which is useful to introduce
14049 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
14050 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
14051 should be careful when using some characters for example @samp{@@} and
14052 curly braces which are the basic special characters in Texinfo
14053 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
14054 such as @command{guix package --show} take care of rendering it
14057 Synopses and descriptions are translated by volunteers
14058 @uref{http://translationproject.org/domain/guix-packages.html, at the
14059 Translation Project} so that as many users as possible can read them in
14060 their native language. User interfaces search them and display them in
14061 the language specified by the current locale.
14063 Translation is a lot of work so, as a packager, please pay even more
14064 attention to your synopses and descriptions as every change may entail
14065 additional work for translators. In order to help them, it is possible
14066 to make recommendations or instructions visible to them by inserting
14067 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
14071 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
14072 (description "ARandR is designed to provide a simple visual front end
14073 for the X11 resize-and-rotate (RandR) extension. @dots{}")
14077 @node Python Modules
14078 @subsection Python Modules
14081 We currently package Python 2 and Python 3, under the Scheme variable names
14082 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
14083 To avoid confusion and naming clashes with other programming languages, it
14084 seems desirable that the name of a package for a Python module contains
14085 the word @code{python}.
14087 Some modules are compatible with only one version of Python, others with both.
14088 If the package Foo compiles only with Python 3, we name it
14089 @code{python-foo}; if it compiles only with Python 2, we name it
14090 @code{python2-foo}. If it is compatible with both versions, we create two
14091 packages with the corresponding names.
14093 If a project already contains the word @code{python}, we drop this;
14094 for instance, the module python-dateutil is packaged under the names
14095 @code{python-dateutil} and @code{python2-dateutil}. If the project name
14096 starts with @code{py} (e.g. @code{pytz}), we keep it and prefix it as
14099 @subsubsection Specifying Dependencies
14100 @cindex inputs, for Python packages
14102 Dependency information for Python packages is usually available in the
14103 package source tree, with varying degrees of accuracy: in the
14104 @file{setup.py} file, in @file{requirements.txt}, or in @file{tox.ini}.
14106 Your mission, when writing a recipe for a Python package, is to map
14107 these dependencies to the appropriate type of ``input'' (@pxref{package
14108 Reference, inputs}). Although the @code{pypi} importer normally does a
14109 good job (@pxref{Invoking guix import}), you may want to check the
14110 following check list to determine which dependency goes where.
14115 We currently package Python 2 with @code{setuptools} and @code{pip}
14116 installed like Python 3.4 has per default. Thus you don't need to
14117 specify either of these as an input. @command{guix lint} will warn you
14121 Python dependencies required at run time go into
14122 @code{propagated-inputs}. They are typically defined with the
14123 @code{install_requires} keyword in @file{setup.py}, or in the
14124 @file{requirements.txt} file.
14127 Python packages required only at build time---e.g., those listed with
14128 the @code{setup_requires} keyword in @file{setup.py}---or only for
14129 testing---e.g., those in @code{tests_require}---go into
14130 @code{native-inputs}. The rationale is that (1) they do not need to be
14131 propagated because they are not needed at run time, and (2) in a
14132 cross-compilation context, it's the ``native'' input that we'd want.
14134 Examples are the @code{pytest}, @code{mock}, and @code{nose} test
14135 frameworks. Of course if any of these packages is also required at
14136 run-time, it needs to go to @code{propagated-inputs}.
14139 Anything that does not fall in the previous categories goes to
14140 @code{inputs}, for example programs or C libraries required for building
14141 Python packages containing C extensions.
14144 If a Python package has optional dependencies (@code{extras_require}),
14145 it is up to you to decide whether to add them or not, based on their
14146 usefulness/overhead ratio (@pxref{Submitting Patches, @command{guix
14153 @subsection Perl Modules
14156 Perl programs standing for themselves are named as any other package,
14157 using the lowercase upstream name.
14158 For Perl packages containing a single class, we use the lowercase class name,
14159 replace all occurrences of @code{::} by dashes and prepend the prefix
14161 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
14162 Modules containing several classes keep their lowercase upstream name and
14163 are also prepended by @code{perl-}. Such modules tend to have the word
14164 @code{perl} somewhere in their name, which gets dropped in favor of the
14165 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
14168 @node Java Packages
14169 @subsection Java Packages
14172 Java programs standing for themselves are named as any other package,
14173 using the lowercase upstream name.
14175 To avoid confusion and naming clashes with other programming languages,
14176 it is desirable that the name of a package for a Java package is
14177 prefixed with @code{java-}. If a project already contains the word
14178 @code{java}, we drop this; for instance, the package @code{ngsjava} is
14179 packaged under the name @code{java-ngs}.
14181 For Java packages containing a single class or a small class hierarchy,
14182 we use the lowercase class name, replace all occurrences of @code{.} by
14183 dashes and prepend the prefix @code{java-}. So the class
14184 @code{apache.commons.cli} becomes package
14185 @code{java-apache-commons-cli}.
14192 For fonts that are in general not installed by a user for typesetting
14193 purposes, or that are distributed as part of a larger software package,
14194 we rely on the general packaging rules for software; for instance, this
14195 applies to the fonts delivered as part of the X.Org system or fonts that
14196 are part of TeX Live.
14198 To make it easier for a user to search for fonts, names for other packages
14199 containing only fonts are constructed as follows, independently of the
14200 upstream package name.
14202 The name of a package containing only one font family starts with
14203 @code{font-}; it is followed by the foundry name and a dash @code{-}
14204 if the foundry is known, and the font family name, in which spaces are
14205 replaced by dashes (and as usual, all upper case letters are transformed
14207 For example, the Gentium font family by SIL is packaged under the name
14208 @code{font-sil-gentium}.
14210 For a package containing several font families, the name of the collection
14211 is used in the place of the font family name.
14212 For instance, the Liberation fonts consist of three families,
14213 Liberation Sans, Liberation Serif and Liberation Mono.
14214 These could be packaged separately under the names
14215 @code{font-liberation-sans} and so on; but as they are distributed together
14216 under a common name, we prefer to package them together as
14217 @code{font-liberation}.
14219 In the case where several formats of the same font family or font collection
14220 are packaged separately, a short form of the format, prepended by a dash,
14221 is added to the package name. We use @code{-ttf} for TrueType fonts,
14222 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
14227 @node Bootstrapping
14228 @section Bootstrapping
14230 @c Adapted from the ELS 2013 paper.
14232 @cindex bootstrapping
14234 Bootstrapping in our context refers to how the distribution gets built
14235 ``from nothing''. Remember that the build environment of a derivation
14236 contains nothing but its declared inputs (@pxref{Introduction}). So
14237 there's an obvious chicken-and-egg problem: how does the first package
14238 get built? How does the first compiler get compiled? Note that this is
14239 a question of interest only to the curious hacker, not to the regular
14240 user, so you can shamelessly skip this section if you consider yourself
14241 a ``regular user''.
14243 @cindex bootstrap binaries
14244 The GNU system is primarily made of C code, with libc at its core. The
14245 GNU build system itself assumes the availability of a Bourne shell and
14246 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
14247 `grep'. Furthermore, build programs---programs that run
14248 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
14249 (@pxref{Derivations}). Consequently, to be able to build anything at
14250 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
14251 Binutils, libc, and the other packages mentioned above---the
14252 @dfn{bootstrap binaries}.
14254 These bootstrap binaries are ``taken for granted'', though we can also
14255 re-create them if needed (more on that later).
14257 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
14259 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
14260 @c large image, it's hard to scroll. Oh well.
14261 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
14263 The figure above shows the very beginning of the dependency graph of the
14264 distribution, corresponding to the package definitions of the @code{(gnu
14265 packages bootstrap)} module. A similar figure can be generated with
14266 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
14269 guix graph -t derivation \
14270 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
14274 At this level of detail, things are
14275 slightly complex. First, Guile itself consists of an ELF executable,
14276 along with many source and compiled Scheme files that are dynamically
14277 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
14278 tarball shown in this graph. This tarball is part of Guix's ``source''
14279 distribution, and gets inserted into the store with @code{add-to-store}
14280 (@pxref{The Store}).
14282 But how do we write a derivation that unpacks this tarball and adds it
14283 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
14284 derivation---the first one that gets built---uses @code{bash} as its
14285 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
14286 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
14287 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
14288 the Guix source distribution, whose sole purpose is to allow the Guile
14289 tarball to be unpacked.
14291 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
14292 Guile that can be used to run subsequent build programs. Its first task
14293 is to download tarballs containing the other pre-built binaries---this
14294 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
14295 @code{ftp-client.scm} are used for this purpose. The
14296 @code{module-import.drv} derivations import those modules in a directory
14297 in the store, using the original layout. The
14298 @code{module-import-compiled.drv} derivations compile those modules, and
14299 write them in an output directory with the right layout. This
14300 corresponds to the @code{#:modules} argument of
14301 @code{build-expression->derivation} (@pxref{Derivations}).
14303 Finally, the various tarballs are unpacked by the
14304 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
14305 etc., at which point we have a working C tool chain.
14308 @unnumberedsubsec Building the Build Tools
14310 Bootstrapping is complete when we have a full tool chain that does not
14311 depend on the pre-built bootstrap tools discussed above. This
14312 no-dependency requirement is verified by checking whether the files of
14313 the final tool chain contain references to the @file{/gnu/store}
14314 directories of the bootstrap inputs. The process that leads to this
14315 ``final'' tool chain is described by the package definitions found in
14316 the @code{(gnu packages commencement)} module.
14318 The @command{guix graph} command allows us to ``zoom out'' compared to
14319 the graph above, by looking at the level of package objects instead of
14320 individual derivations---remember that a package may translate to
14321 several derivations, typically one derivation to download its source,
14322 one to build the Guile modules it needs, and one to actually build the
14323 package from source. The command:
14326 guix graph -t bag \
14327 -e '(@@@@ (gnu packages commencement)
14328 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
14332 produces the dependency graph leading to the ``final'' C
14333 library@footnote{You may notice the @code{glibc-intermediate} label,
14334 suggesting that it is not @emph{quite} final, but as a good
14335 approximation, we will consider it final.}, depicted below.
14337 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
14339 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
14340 The first tool that gets built with the bootstrap binaries is
14341 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
14342 for all the following packages. From there Findutils and Diffutils get
14345 Then come the first-stage Binutils and GCC, built as pseudo cross
14346 tools---i.e., with @code{--target} equal to @code{--host}. They are
14347 used to build libc. Thanks to this cross-build trick, this libc is
14348 guaranteed not to hold any reference to the initial tool chain.
14350 From there the final Binutils and GCC (not shown above) are built.
14352 from the final Binutils, and links programs against the just-built libc.
14353 This tool chain is used to build the other packages used by Guix and by
14354 the GNU Build System: Guile, Bash, Coreutils, etc.
14356 And voilà! At this point we have the complete set of build tools that
14357 the GNU Build System expects. These are in the @code{%final-inputs}
14358 variable of the @code{(gnu packages commencement)} module, and are
14359 implicitly used by any package that uses @code{gnu-build-system}
14360 (@pxref{Build Systems, @code{gnu-build-system}}).
14363 @unnumberedsubsec Building the Bootstrap Binaries
14365 @cindex bootstrap binaries
14366 Because the final tool chain does not depend on the bootstrap binaries,
14367 those rarely need to be updated. Nevertheless, it is useful to have an
14368 automated way to produce them, should an update occur, and this is what
14369 the @code{(gnu packages make-bootstrap)} module provides.
14371 The following command builds the tarballs containing the bootstrap
14372 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
14373 of Coreutils and other basic command-line tools):
14376 guix build bootstrap-tarballs
14379 The generated tarballs are those that should be referred to in the
14380 @code{(gnu packages bootstrap)} module mentioned at the beginning of
14383 Still here? Then perhaps by now you've started to wonder: when do we
14384 reach a fixed point? That is an interesting question! The answer is
14385 unknown, but if you would like to investigate further (and have
14386 significant computational and storage resources to do so), then let us
14390 @section Porting to a New Platform
14392 As discussed above, the GNU distribution is self-contained, and
14393 self-containment is achieved by relying on pre-built ``bootstrap
14394 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
14395 operating system kernel, CPU architecture, and application binary
14396 interface (ABI). Thus, to port the distribution to a platform that is
14397 not yet supported, one must build those bootstrap binaries, and update
14398 the @code{(gnu packages bootstrap)} module to use them on that platform.
14400 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
14401 When everything goes well, and assuming the GNU tool chain supports the
14402 target platform, this can be as simple as running a command like this
14406 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
14409 For this to work, the @code{glibc-dynamic-linker} procedure in
14410 @code{(gnu packages bootstrap)} must be augmented to return the right
14411 file name for libc's dynamic linker on that platform; likewise,
14412 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
14413 taught about the new platform.
14415 Once these are built, the @code{(gnu packages bootstrap)} module needs
14416 to be updated to refer to these binaries on the target platform. That
14417 is, the hashes and URLs of the bootstrap tarballs for the new platform
14418 must be added alongside those of the currently supported platforms. The
14419 bootstrap Guile tarball is treated specially: it is expected to be
14420 available locally, and @file{gnu/local.mk} has rules do download it for
14421 the supported architectures; a rule for the new platform must be added
14424 In practice, there may be some complications. First, it may be that the
14425 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
14426 above) is not recognized by all the GNU tools. Typically, glibc
14427 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
14428 configure flag (see @code{gcc.scm} for examples of how to handle this).
14429 Second, some of the required packages could fail to build for that
14430 platform. Lastly, the generated binaries could be broken for some
14433 @c *********************************************************************
14434 @include contributing.texi
14436 @c *********************************************************************
14437 @node Acknowledgments
14438 @chapter Acknowledgments
14440 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
14441 which was designed and
14442 implemented by Eelco Dolstra, with contributions from other people (see
14443 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
14444 management, and promoted unprecedented features, such as transactional
14445 package upgrades and rollbacks, per-user profiles, and referentially
14446 transparent build processes. Without this work, Guix would not exist.
14448 The Nix-based software distributions, Nixpkgs and NixOS, have also been
14449 an inspiration for Guix.
14451 GNU@tie{}Guix itself is a collective work with contributions from a
14452 number of people. See the @file{AUTHORS} file in Guix for more
14453 information on these fine people. The @file{THANKS} file lists people
14454 who have helped by reporting bugs, taking care of the infrastructure,
14455 providing artwork and themes, making suggestions, and more---thank you!
14458 @c *********************************************************************
14459 @node GNU Free Documentation License
14460 @appendix GNU Free Documentation License
14461 @cindex license, GNU Free Documentation License
14462 @include fdl-1.3.texi
14464 @c *********************************************************************
14465 @node Concept Index
14466 @unnumbered Concept Index
14469 @node Programming Index
14470 @unnumbered Programming Index
14471 @syncodeindex tp fn
14472 @syncodeindex vr fn
14477 @c Local Variables:
14478 @c ispell-local-dictionary: "american";