1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM
"version.ent"> %versiondata;
5 <!-- current Debian changes file format -->
6 <!entity changesversion
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12 <title>Debian Policy Manual
</title>
13 <author><qref id=
"authors">The Debian Policy Mailing List
</qref></author>
14 <version>version
&version;,
&date;</version>
17 This manual describes the policy requirements for the Debian
18 GNU/Linux distribution. This includes the structure and
19 contents of the Debian archive and several design issues of
20 the operating system, as well as technical requirements that
21 each package must satisfy to be included in the distribution.
26 Copyright
© 1996,
1997,
1998 Ian Jackson
27 and Christian Schwarz.
30 These are the copyright dates of the original Policy manual.
31 Since then, this manual has been updated by many others. No
32 comprehensive collection of copyright notices for subsequent
37 This manual is free software; you may redistribute it and/or
38 modify it under the terms of the GNU General Public License
39 as published by the Free Software Foundation; either version
40 2, or (at your option) any later version.
44 This is distributed in the hope that it will be useful, but
45 <em>without any warranty
</em>; without even the implied
46 warranty of merchantability or fitness for a particular
47 purpose. See the GNU General Public License for more
52 A copy of the GNU General Public License is available as
53 <file>/usr/share/common-licenses/GPL
</file> in the Debian GNU/Linux
54 distribution or on the World Wide Web at
55 <url id=
"http://www.gnu.org/copyleft/gpl.html"
56 name=
"the GNU General Public Licence">. You can also
57 obtain it by writing to the Free Software Foundation, Inc.,
58 51 Franklin St, Fifth Floor, Boston, MA
02110-
1301, USA.
66 <heading>About this manual
</heading>
68 <heading>Scope
</heading>
70 This manual describes the policy requirements for the Debian
71 GNU/Linux distribution. This includes the structure and
72 contents of the Debian archive and several design issues of the
73 operating system, as well as technical requirements that
74 each package must satisfy to be included in the
79 This manual also describes Debian policy as it relates to
80 creating Debian packages. It is not a tutorial on how to build
81 packages, nor is it exhaustive where it comes to describing
82 the behavior of the packaging system. Instead, this manual
83 attempts to define the interface to the package management
84 system that the developers have to be conversant with.
<footnote>
85 Informally, the criteria used for inclusion is that the
86 material meet one of the following requirements:
87 <taglist compact=
"compact">
88 <tag>Standard interfaces
</tag>
90 The material presented represents an interface to
91 the packaging system that is mandated for use, and
92 is used by, a significant number of packages, and
93 therefore should not be changed without peer
94 review. Package maintainers can then rely on this
95 interface not changing, and the package management
96 software authors need to ensure compatibility with
97 this interface definition. (Control file and
98 changelog file formats are examples.)
100 <tag>Chosen Convention
</tag>
102 If there are a number of technically viable choices
103 that can be made, but one needs to select one of
104 these options for inter-operability. The version
105 number format is one example.
108 Please note that these are not mutually exclusive;
109 selected conventions often become parts of standard
115 The footnotes present in this manual are
116 merely informative, and are not part of Debian policy itself.
120 The appendices to this manual are not necessarily normative,
121 either. Please see
<ref id=
"pkg-scope"> for more information.
125 In the normative part of this manual,
126 the words
<em>must
</em>,
<em>should
</em> and
127 <em>may
</em>, and the adjectives
<em>required
</em>,
128 <em>recommended
</em> and
<em>optional
</em>, are used to
129 distinguish the significance of the various guidelines in
130 this policy document. Packages that do not conform to the
131 guidelines denoted by
<em>must
</em> (or
<em>required
</em>)
132 will generally not be considered acceptable for the Debian
133 distribution. Non-conformance with guidelines denoted by
134 <em>should
</em> (or
<em>recommended
</em>) will generally be
135 considered a bug, but will not necessarily render a package
136 unsuitable for distribution. Guidelines denoted by
137 <em>may
</em> (or
<em>optional
</em>) are truly optional and
138 adherence is left to the maintainer's discretion.
142 These classifications are roughly equivalent to the bug
143 severities
<em>serious
</em> (for
<em>must
</em> or
144 <em>required
</em> directive violations),
<em>minor
</em>,
145 <em>normal
</em> or
<em>important
</em>
146 (for
<em>should
</em> or
<em>recommended
</em> directive
147 violations) and
<em>wishlist
</em> (for
<em>optional
</em>
150 Compare RFC
2119. Note, however, that these words are
151 used in a different way in this document.
156 Much of the information presented in this manual will be
157 useful even when building a package which is to be
158 distributed in some other way or is intended for local use
164 <heading>New versions of this document
</heading>
167 This manual is distributed via the Debian package
168 <package><url name=
"debian-policy"
169 id=
"http://packages.debian.org/debian-policy"></package>
170 (
<httpsite>packages.debian.org
</httpsite>
171 <httppath>/debian-policy
</httppath>).
175 The current version of this document is also available from
176 the Debian web mirrors at
177 <tt><url name=
"/doc/debian-policy/"
178 id=
"http://www.debian.org/doc/debian-policy/"></tt>.
180 <httpsite>www.debian.org
</httpsite>
181 <httppath>/doc/debian-policy/
</httppath>)
182 Also available from the same directory are several other
183 formats:
<file>policy.html.tar.gz
</file>
184 (
<httppath>/doc/debian-policy/policy.html.tar.gz
</httppath>),
185 <file>policy.pdf.gz
</file>
186 (
<httppath>/doc/debian-policy/policy.pdf.gz
</httppath>)
187 and
<file>policy.ps.gz
</file>
188 (
<httppath>/doc/debian-policy/policy.ps.gz
</httppath>).
192 The
<package>debian-policy
</package> package also includes the file
193 <file>upgrading-checklist.txt.gz
</file> which indicates policy
194 changes between versions of this document.
199 <heading>Authors and Maintainers
</heading>
202 Originally called
"Debian GNU/Linux Policy Manual", this
203 manual was initially written in
1996 by Ian Jackson.
204 It was revised on November
27th,
1996 by David A. Morris.
205 Christian Schwarz added new sections on March
15th,
1997,
206 and reworked/restructured it in April-July
1997.
207 Christoph Lameter contributed the
"Web Standard".
208 Julian Gilbey largely restructured it in
2001.
212 Since September
1998, the responsibility for the contents of
213 this document lies on the
<url name=
"debian-policy mailing list"
214 id=
"mailto:debian-policy@lists.debian.org">. Proposals
215 are discussed there and inserted into policy after a certain
216 consensus is established.
217 <!-- insert shameless policy-process plug here eventually -->
218 The actual editing is done by a group of maintainers that have
219 no editorial powers. These are the current maintainers:
222 <item>Julian Gilbey
</item>
223 <item>Branden Robinson
</item>
224 <item>Josip Rodin
</item>
225 <item>Manoj Srivastava
</item>
230 While the authors of this document have tried hard to avoid
231 typos and other errors, these do still occur. If you discover
232 an error in this manual or if you want to give any
233 comments, suggestions, or criticisms please send an email to
234 the Debian Policy List,
235 <email>debian-policy@lists.debian.org
</email>, or submit a
236 bug report against the
<tt>debian-policy
</tt> package.
240 Please do not try to reach the individual authors or maintainers
241 of the Policy Manual regarding changes to the Policy.
246 <heading>Related documents
</heading>
249 There are several other documents other than this Policy Manual
250 that are necessary to fully understand some Debian policies and
255 The external
"sub-policy" documents are referred to in:
256 <list compact=
"compact">
257 <item><ref id=
"fhs"></item>
258 <item><ref id=
"virtual_pkg"></item>
259 <item><ref id=
"menus"></item>
260 <item><ref id=
"mime"></item>
261 <item><ref id=
"perl"></item>
262 <item><ref id=
"maintscriptprompt"></item>
263 <item><ref id=
"emacs"></item>
268 In addition to those, which carry the weight of policy, there
269 is the Debian Developer's Reference. This document describes
270 procedures and resources for Debian developers, but it is
271 <em>not
</em> normative; rather, it includes things that don't
272 belong in the Policy, such as best practices for developers.
276 The Developer's Reference is available in the
277 <package>developers-reference
</package> package.
278 It's also available from the Debian web mirrors at
279 <tt><url name=
"/doc/developers-reference/"
280 id=
"http://www.debian.org/doc/developers-reference/"></tt>.
284 <sect id=
"definitions">
285 <heading>Definitions
</heading>
288 The following terms are used in this Policy Manual:
292 The character encoding specified by ANSI X3.4-
1986 and its
293 predecessor standards, referred to in MIME as US-ASCII, and
294 corresponding to an encoding in eight bits per character of
295 the first
128 <url id=
"http://www.unicode.org/"
296 name=
"Unicode"> characters, with the eighth bit always zero.
300 The transformation format (sometimes called encoding) of
301 <url id=
"http://www.unicode.org/" name=
"Unicode"> defined by
302 <url id=
"http://www.rfc-editor.org/rfc/rfc3629.txt"
303 name=
"RFC 3629">. UTF-
8 has the useful property of having
304 ASCII as a subset, so any text encoded in ASCII is trivially
314 <heading>The Debian Archive
</heading>
317 The Debian GNU/Linux system is maintained and distributed as a
318 collection of
<em>packages
</em>. Since there are so many of
319 them (currently well over
15000), they are split into
320 <em>sections
</em> and given
<em>priorities
</em> to simplify
321 the handling of them.
325 The effort of the Debian project is to build a free operating
326 system, but not every package we want to make accessible is
327 <em>free
</em> in our sense (see the Debian Free Software
328 Guidelines, below), or may be imported/exported without
329 restrictions. Thus, the archive is split into areas
<footnote>
330 The Debian archive software uses the term
"component" internally
331 and in the Release file format to refer to the division of an
332 archive. The Debian Social Contract simply refers to
"areas."
333 This document uses terminology similar to the Social Contract.
334 </footnote> based on their licenses and other restrictions.
338 The aims of this are:
340 <list compact=
"compact">
341 <item>to allow us to make as much software available as we can
</item>
342 <item>to allow us to encourage everyone to write free software,
344 <item>to allow us to make it easy for people to produce
345 CD-ROMs of our system without violating any licenses,
346 import/export restrictions, or any other laws.
</item>
351 The
<em>main
</em> archive area forms the
<em>Debian GNU/Linux
356 Packages in the other archive areas (
<tt>contrib
</tt>,
357 <tt>non-free
</tt>) are not considered to be part of the Debian
358 distribution, although we support their use and provide
359 infrastructure for them (such as our bug-tracking system and
360 mailing lists). This Debian Policy Manual applies to these
365 <heading>The Debian Free Software Guidelines
</heading>
367 The Debian Free Software Guidelines (DFSG) form our
368 definition of
"free software". These are:
370 <tag>1. Free Redistribution
373 The license of a Debian component may not restrict any
374 party from selling or giving away the software as a
375 component of an aggregate software distribution
376 containing programs from several different
377 sources. The license may not require a royalty or
378 other fee for such sale.
383 The program must include source code, and must allow
384 distribution in source code as well as compiled form.
386 <tag>3. Derived Works
389 The license must allow modifications and derived
390 works, and must allow them to be distributed under the
391 same terms as the license of the original software.
393 <tag>4. Integrity of The Author's Source Code
396 The license may restrict source-code from being
397 distributed in modified form
<em>only
</em> if the
398 license allows the distribution of
"patch files"
399 with the source code for the purpose of modifying the
400 program at build time. The license must explicitly
401 permit distribution of software built from modified
402 source code. The license may require derived works to
403 carry a different name or version number from the
404 original software. (This is a compromise. The Debian
405 Project encourages all authors to not restrict any
406 files, source or binary, from being modified.)
408 <tag>5. No Discrimination Against Persons or Groups
411 The license must not discriminate against any person
414 <tag>6. No Discrimination Against Fields of Endeavor
417 The license must not restrict anyone from making use
418 of the program in a specific field of endeavor. For
419 example, it may not restrict the program from being
420 used in a business, or from being used for genetic
423 <tag>7. Distribution of License
426 The rights attached to the program must apply to all
427 to whom the program is redistributed without the need
428 for execution of an additional license by those
431 <tag>8. License Must Not Be Specific to Debian
434 The rights attached to the program must not depend on
435 the program's being part of a Debian system. If the
436 program is extracted from Debian and used or
437 distributed without Debian but otherwise within the
438 terms of the program's license, all parties to whom
439 the program is redistributed must have the same
440 rights as those that are granted in conjunction with
443 <tag>9. License Must Not Contaminate Other Software
446 The license must not place restrictions on other
447 software that is distributed along with the licensed
448 software. For example, the license must not insist
449 that all other programs distributed on the same medium
450 must be free software.
452 <tag>10. Example Licenses
455 The
"GPL," "BSD," and
"Artistic" licenses are examples of
456 licenses that we consider
<em>free
</em>.
463 <heading>Archive areas
</heading>
466 <heading>The main archive area
</heading>
469 Every package in
<em>main
</em> must comply with the DFSG
470 (Debian Free Software Guidelines).
474 In addition, the packages in
<em>main
</em>
475 <list compact=
"compact">
477 must not require a package outside of
<em>main
</em>
478 for compilation or execution (thus, the package must
479 not declare a
"Depends",
"Recommends", or
480 "Build-Depends" relationship on a non-
<em>main
</em>
484 must not be so buggy that we refuse to support them,
488 must meet all policy requirements presented in this
497 <heading>The contrib archive area
</heading>
500 Every package in
<em>contrib
</em> must comply with the DFSG.
504 In addition, the packages in
<em>contrib
</em>
505 <list compact=
"compact">
507 must not be so buggy that we refuse to support them,
511 must meet all policy requirements presented in this
519 Examples of packages which would be included in
520 <em>contrib
</em> are:
521 <list compact=
"compact">
523 free packages which require
<em>contrib
</em>,
524 <em>non-free
</em> packages or packages which are not
525 in our archive at all for compilation or execution,
529 wrapper packages or other sorts of free accessories for
536 <sect1 id=
"non-free">
537 <heading>The non-free archive area
</heading>
540 Packages must be placed in
<em>non-free
</em> if they are
541 not compliant with the DFSG or are encumbered by patents
542 or other legal issues that make their distribution
547 In addition, the packages in
<em>non-free
</em>
548 <list compact=
"compact">
550 must not be so buggy that we refuse to support them,
554 must meet all policy requirements presented in this
555 manual that it is possible for them to meet.
557 It is possible that there are policy
558 requirements which the package is unable to
559 meet, for example, if the source is
560 unavailable. These situations will need to be
561 handled on a case-by-case basis.
570 <sect id=
"pkgcopyright">
571 <heading>Copyright considerations
</heading>
574 Every package must be accompanied by a verbatim copy of its
575 copyright information and distribution license in the file
576 <file>/usr/share/doc/
<var>package
</var>/copyright
</file>
577 (see
<ref id=
"copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact=
"compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in
<em>non-free
</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too),
<em>no
</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice
<em>is
</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the
<tt>debian-legal
</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org
</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases
"commercial
645 use prohibited" and
"distribution restricted".
649 <sect id=
"subsections">
650 <heading>Sections
</heading>
653 The packages in the archive areas
<em>main
</em>,
654 <em>contrib
</em> and
<em>non-free
</em> are grouped further into
655 <em>sections
</em> to simplify handling.
659 The archive area and section for each package should be
660 specified in the package's
<tt>Section
</tt> control record (see
661 <ref id=
"f-Section">). However, the maintainer of the Debian
662 archive may override this selection to ensure the consistency of
663 the Debian distribution. The
<tt>Section
</tt> field should be
665 <list compact=
"compact">
667 <em>section
</em> if the package is in the
668 <em>main
</em> archive area,
671 <em>area/section
</em> if the package is in
672 the
<em>contrib
</em> or
<em>non-free
</em>
679 The Debian archive maintainers provide the authoritative
680 list of sections. At present, they are:
681 <em>admin
</em>,
<em>cli-mono
</em>,
<em>comm
</em>,
<em>database
</em>,
682 <em>devel
</em>,
<em>debug
</em>,
<em>doc
</em>,
<em>editors
</em>,
683 <em>electronics
</em>,
<em>embedded
</em>,
<em>fonts
</em>,
684 <em>games
</em>,
<em>gnome
</em>,
<em>graphics
</em>,
<em>gnu-r
</em>,
685 <em>gnustep
</em>,
<em>hamradio
</em>,
<em>haskell
</em>,
686 <em>httpd
</em>,
<em>interpreters
</em>,
<em>java
</em>,
<em>kde
</em>,
687 <em>kernel
</em>,
<em>libs
</em>,
<em>libdevel
</em>,
<em>lisp
</em>,
688 <em>localization
</em>,
<em>mail
</em>,
<em>math
</em>,
<em>misc
</em>,
689 <em>net
</em>,
<em>news
</em>,
<em>ocaml
</em>,
<em>oldlibs
</em>,
690 <em>otherosfs
</em>,
<em>perl
</em>,
<em>php
</em>,
<em>python
</em>,
691 <em>ruby
</em>,
<em>science
</em>,
<em>shells
</em>,
<em>sound
</em>,
692 <em>tex
</em>,
<em>text
</em>,
<em>utils
</em>,
<em>vcs
</em>,
693 <em>video
</em>,
<em>web
</em>,
<em>x11
</em>,
<em>xfce
</em>,
694 <em>zope
</em>. The additional section
<em>debian-installer
</em>
695 contains special packages used by the installer and is not used
696 for normal Debian packages.
700 For more information about the sections and their definitions,
701 see the
<url id=
"http://packages.debian.org/unstable/"
702 name=
"list of sections in unstable">.
706 <sect id=
"priorities">
707 <heading>Priorities
</heading>
710 Each package should have a
<em>priority
</em> value, which is
711 included in the package's
<em>control record
</em>
712 (see
<ref id=
"f-Priority">).
713 This information is used by the Debian package management tools to
714 separate high-priority packages from less-important packages.
718 The following
<em>priority levels
</em> are recognized by the
719 Debian package management tools.
721 <tag><tt>required
</tt></tag>
723 Packages which are necessary for the proper
724 functioning of the system (usually, this means that
725 dpkg functionality depends on these packages).
726 Removing a
<tt>required
</tt> package may cause your
727 system to become totally broken and you may not even
728 be able to use
<prgn>dpkg
</prgn> to put things back,
729 so only do so if you know what you are doing. Systems
730 with only the
<tt>required
</tt> packages are probably
731 unusable, but they do have enough functionality to
732 allow the sysadmin to boot and install more software.
734 <tag><tt>important
</tt></tag>
736 Important programs, including those which one would
737 expect to find on any Unix-like system. If the
738 expectation is that an experienced Unix person who
739 found it missing would say
"What on earth is going on,
740 where is <prgn>foo</prgn>?", it must be an
741 <tt>important
</tt> package.
<footnote>
742 This is an important criterion because we are
743 trying to produce, amongst other things, a free
746 Other packages without which the system will not run
747 well or be usable must also have priority
748 <tt>important
</tt>. This does
749 <em>not
</em> include Emacs, the X Window System, TeX
750 or any other large applications. The
751 <tt>important
</tt> packages are just a bare minimum of
752 commonly-expected and necessary tools.
754 <tag><tt>standard
</tt></tag>
756 These packages provide a reasonably small but not too
757 limited character-mode system. This is what will be
758 installed by default if the user doesn't select anything
759 else. It doesn't include many large applications.
761 <tag><tt>optional
</tt></tag>
763 (In a sense everything that isn't required is
764 optional, but that's not what is meant here.) This is
765 all the software that you might reasonably want to
766 install if you didn't know what it was and don't have
767 specialized requirements. This is a much larger system
768 and includes the X Window System, a full TeX
769 distribution, and many applications. Note that
770 optional packages should not conflict with each other.
772 <tag><tt>extra
</tt></tag>
774 This contains all packages that conflict with others
775 with required, important, standard or optional
776 priorities, or are only likely to be useful if you
777 already know what they are or have specialized
778 requirements (such as packages containing only detached
785 Packages must not depend on packages with lower priority
786 values (excluding build-time dependencies). In order to
787 ensure this, the priorities of one or more packages may need
796 <heading>Binary packages
</heading>
799 The Debian GNU/Linux distribution is based on the Debian
800 package management system, called
<prgn>dpkg
</prgn>. Thus,
801 all packages in the Debian distribution must be provided
802 in the
<tt>.deb
</tt> file format.
806 A
<tt>.deb
</tt> package contains two sets of files: a set of files
807 to install on the system when the package is installed, and a set
808 of files that provide additional metadata about the package or
809 which are executed when the package is installed or removed. This
810 second set of files is called
<em>control information files
</em>.
811 Among those files are the package maintainer scripts
812 and
<file>control
</file>, the
<qref id=
"binarycontrolfiles">binary
813 package control file
</qref> that contains the control fields for
814 the package. Other control information files
815 include
<qref id=
"sharedlibs-shlibdeps">the
<file>shlibs
</file>
816 file
</qref> used to store shared library dependency information
817 and the
<file>conffiles
</file> file that lists the package's
818 configuration files (described in
<ref id=
"config-files">).
822 There is unfortunately a collision of terminology here between
823 control information files and files in the Debian control file
824 format. Throughout this document, a
<em>control file
</em> refers
825 to a file in the Debian control file format. These files are
826 documented in
<ref id=
"controlfields">. Only files referred to
827 specifically as
<em>control information files
</em> are the files
828 included in the control information file member of
829 the
<file>.deb
</file> file format used by binary packages. Most
830 control information files are not in the Debian control file
835 <heading>The package name
</heading>
838 Every package must have a name that's unique within the Debian
843 The package name is included in the control field
844 <tt>Package
</tt>, the format of which is described
845 in
<ref id=
"f-Package">.
846 The package name is also included as a part of the file name
847 of the
<tt>.deb
</tt> file.
852 <heading>The version of a package
</heading>
855 Every package has a version number recorded in its
856 <tt>Version
</tt> control file field, described in
857 <ref id=
"f-Version">.
861 The package management system imposes an ordering on version
862 numbers, so that it can tell whether packages are being up- or
863 downgraded and so that package system front end applications
864 can tell whether a package it finds available is newer than
865 the one installed on the system. The version number format
866 has the most significant parts (as far as comparison is
867 concerned) at the beginning.
871 If an upstream package has problematic version numbers they
872 should be converted to a sane form for use in the
873 <tt>Version
</tt> field.
877 <heading>Version numbers based on dates
</heading>
880 In general, Debian packages should use the same version
881 numbers as the upstream sources. However, upstream version
882 numbers based on some date formats (sometimes used for
883 development or
"snapshot" releases) will not be ordered
884 correctly by the package management software. For
885 example,
<prgn>dpkg
</prgn> will consider
"96May01" to be
886 greater than
"96Dec24".
890 To prevent having to use epochs for every new upstream
891 version, the date-based portion of any upstream version number
892 should be given in a way that sorts correctly: four-digit year
893 first, followed by a two-digit numeric month, followed by a
894 two-digit numeric date, possibly with punctuation between the
899 Native Debian packages (i.e., packages which have been written
900 especially for Debian) whose version numbers include dates
901 should also follow these rules. If punctuation is desired
902 between the date components, remember that hyphen (
<tt>-
</tt>)
903 cannot be used in native package versions. Period
904 (
<tt>.
</tt>) is normally a good choice.
910 <sect id=
"maintainer">
911 <heading>The maintainer of a package
</heading>
914 Every package must have a maintainer. The maintainer may be one
915 person or a group of people reachable from a common email
916 address, such as a mailing list. The maintainer is responsible
917 for maintaining the Debian packaging files, evaluating and
918 responding appropriately to reported bugs, uploading new
919 versions of the package (either directly or through a sponsor),
920 ensuring that the package is placed in the appropriate archive
921 area and included in Debian releases as appropriate for the
922 stability and utility of the package, and requesting removal of
923 the package from the Debian distribution if it is no longer
924 useful or maintainable.
928 The maintainer must be specified in the
<tt>Maintainer
</tt>
929 control field with their correct name and a working email
930 address. The email address given in the
<tt>Maintainer
</tt>
931 control field must accept mail from those role accounts in
932 Debian used to send automated mails regarding the package. This
933 includes non-spam mail from the bug-tracking system, all mail
934 from the Debian archive maintenance software, and other role
935 accounts or automated processes that are commonly agreed on by
936 the project.
<footnote>
937 A sample implementation of such a whitelist written for the
938 Mailman mailing list management software is used for mailing
939 lists hosted by alioth.debian.org.
941 If one person or team maintains several packages, they should
942 use the same form of their name and email address in
943 the
<tt>Maintainer
</tt> fields of those packages.
947 The format of the
<tt>Maintainer
</tt> control field is
948 described in
<ref id=
"f-Maintainer">.
952 If the maintainer of the package is a team of people with a
953 shared email address, the
<tt>Uploaders
</tt> control field must
954 be present and must contain at least one human with their
955 personal email address. See
<ref id=
"f-Uploaders"> for the
956 syntax of that field.
960 If the maintainer of a package no longer has time or desire to
961 maintain a package, it will be orphaned according to the
962 procedure described in the Debian Developer's Reference
963 (see
<ref id=
"related">). The maintainer then
964 becomes
<tt>Debian QA Group
<packages@qa.debian.org
></tt>.
965 These packages are considered maintained by the Debian project
966 as a whole until someone else volunteers to take over
971 <sect id=
"descriptions">
972 <heading>The description of a package
</heading>
975 Every Debian package must have a
<tt>Description
</tt> control
976 field which contains a synopsis and extended description of the
977 package. Technical information about the format of the
978 <tt>Description
</tt> field is in
<ref id=
"f-Description">.
982 The description should describe the package (the program) to a
983 user (system administrator) who has never met it before so that
984 they have enough information to decide whether they want to
985 install it. This description should not just be copied verbatim
986 from the program's documentation.
990 Put important information first, both in the synopsis and
991 extended description. Sometimes only the first part of the
992 synopsis or of the description will be displayed. You can
993 assume that there will usually be a way to see the whole
994 extended description.
998 The description should also give information about the
999 significant dependencies and conflicts between this package
1000 and others, so that the user knows why these dependencies and
1001 conflicts have been declared.
1005 Instructions for configuring or using the package should
1006 not be included (that is what installation scripts,
1007 manual pages, info files, etc., are for). Copyright
1008 statements and other administrivia should not be included
1009 either (that is what the copyright file is for).
1012 <sect1 id=
"synopsis"><heading>The single line synopsis
</heading>
1015 The single line synopsis should be kept brief - certainly
1016 under
80 characters.
1020 Do not include the package name in the synopsis line. The
1021 display software knows how to display this already, and you
1022 do not need to state it. Remember that in many situations
1023 the user may only see the synopsis line - make it as
1024 informative as you can.
1029 <sect1 id=
"extendeddesc"><heading>The extended description
</heading>
1032 Do not try to continue the single line synopsis into the
1033 extended description. This will not work correctly when
1034 the full description is displayed, and makes no sense
1035 where only the summary (the single line synopsis) is
1040 The extended description should describe what the package
1041 does and how it relates to the rest of the system (in terms
1042 of, for example, which subsystem it is which part of).
1046 The description field needs to make sense to anyone, even
1047 people who have no idea about any of the things the
1048 package deals with.
<footnote>
1049 The blurb that comes with a program in its
1050 announcements and/or
<prgn>README
</prgn> files is
1051 rarely suitable for use in a description. It is
1052 usually aimed at people who are already in the
1053 community where the package is used.
1062 <heading>Dependencies
</heading>
1065 Every package must specify the dependency information
1066 about other packages that are required for the first to
1071 For example, a dependency entry must be provided for any
1072 shared libraries required by a dynamically-linked executable
1073 binary in a package.
1077 Packages are not required to declare any dependencies they
1078 have on other packages which are marked
<tt>Essential
</tt>
1079 (see below), and should not do so unless they depend on a
1080 particular version of that package.
<footnote>
1082 Essential is needed in part to avoid unresolvable dependency
1083 loops on upgrade. If packages add unnecessary dependencies
1084 on packages in this set, the chances that there
1085 <strong>will
</strong> be an unresolvable dependency loop
1086 caused by forcing these Essential packages to be configured
1087 first before they need to be is greatly increased. It also
1088 increases the chances that frontends will be unable to
1089 <strong>calculate
</strong> an upgrade path, even if one
1093 Also, functionality is rarely ever removed from the
1094 Essential set, but
<em>packages
</em> have been removed from
1095 the Essential set when the functionality moved to a
1096 different package. So depending on these packages
<em>just
1097 in case
</em> they stop being essential does way more harm
1104 Sometimes, a package requires another package to be installed
1105 <em>and
</em> configured before it can be installed. In this
1106 case, you must specify a
<tt>Pre-Depends
</tt> entry for
1111 You should not specify a
<tt>Pre-Depends
</tt> entry for a
1112 package before this has been discussed on the
1113 <tt>debian-devel
</tt> mailing list and a consensus about
1114 doing that has been reached.
1118 The format of the package interrelationship control fields is
1119 described in
<ref id=
"relationships">.
1123 <sect id=
"virtual_pkg">
1124 <heading>Virtual packages
</heading>
1127 Sometimes, there are several packages which offer
1128 more-or-less the same functionality. In this case, it's
1129 useful to define a
<em>virtual package
</em> whose name
1130 describes that common functionality. (The virtual
1131 packages only exist logically, not physically; that's why
1132 they are called
<em>virtual
</em>.) The packages with this
1133 particular function will then
<em>provide
</em> the virtual
1134 package. Thus, any other package requiring that function
1135 can simply depend on the virtual package without having to
1136 specify all possible packages individually.
1140 All packages should use virtual package names where
1141 appropriate, and arrange to create new ones if necessary.
1142 They should not use virtual package names (except privately,
1143 amongst a cooperating group of packages) unless they have
1144 been agreed upon and appear in the list of virtual package
1145 names. (See also
<ref id=
"virtual">)
1149 The latest version of the authoritative list of virtual
1150 package names can be found in the
<tt>debian-policy
</tt> package.
1151 It is also available from the Debian web mirrors at
1152 <tt><url name=
"/doc/packaging-manuals/virtual-package-names-list.txt"
1153 id=
"http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1157 The procedure for updating the list is described in the preface
1164 <heading>Base system
</heading>
1167 The
<tt>base system
</tt> is a minimum subset of the Debian
1168 GNU/Linux system that is installed before everything else
1169 on a new system. Only very few packages are allowed to form
1170 part of the base system, in order to keep the required disk
1175 The base system consists of all those packages with priority
1176 <tt>required
</tt> or
<tt>important
</tt>. Many of them will
1177 be tagged
<tt>essential
</tt> (see below).
1182 <heading>Essential packages
</heading>
1185 Essential is defined as the minimal set of functionality that
1186 must be available and usable on the system at all times, even
1187 when packages are in an unconfigured (but unpacked) state.
1188 Packages are tagged
<tt>essential
</tt> for a system using the
1189 <tt>Essential
</tt> control field. The format of the
1190 <tt>Essential
</tt> control field is described in
<ref
1195 Since these packages cannot be easily removed (one has to
1196 specify an extra
<em>force option
</em> to
1197 <prgn>dpkg
</prgn> to do so), this flag must not be used
1198 unless absolutely necessary. A shared library package
1199 must not be tagged
<tt>essential
</tt>; dependencies will
1200 prevent its premature removal, and we need to be able to
1201 remove it when it has been superseded.
1205 Since dpkg will not prevent upgrading of other packages
1206 while an
<tt>essential
</tt> package is in an unconfigured
1207 state, all
<tt>essential
</tt> packages must supply all of
1208 their core functionality even when unconfigured. If the
1209 package cannot satisfy this requirement it must not be
1210 tagged as essential, and any packages depending on this
1211 package must instead have explicit dependency fields as
1216 Maintainers should take great care in adding any programs,
1217 interfaces, or functionality to
<tt>essential
</tt> packages.
1218 Packages may assume that functionality provided by
1219 <tt>essential
</tt> packages is always available without
1220 declaring explicit dependencies, which means that removing
1221 functionality from the Essential set is very difficult and is
1222 almost never done. Any capability added to an
1223 <tt>essential
</tt> package therefore creates an obligation to
1224 support that capability as part of the Essential set in
1229 You must not tag any packages
<tt>essential
</tt> before
1230 this has been discussed on the
<tt>debian-devel
</tt>
1231 mailing list and a consensus about doing that has been
1236 <sect id=
"maintscripts">
1237 <heading>Maintainer Scripts
</heading>
1240 The package installation scripts should avoid producing
1241 output which is unnecessary for the user to see and
1242 should rely on
<prgn>dpkg
</prgn> to stave off boredom on
1243 the part of a user installing many packages. This means,
1244 amongst other things, using the
<tt>--quiet
</tt> option on
1245 <prgn>install-info
</prgn>.
1249 Errors which occur during the execution of an installation
1250 script must be checked and the installation must not
1251 continue after an error.
1255 Note that in general
<ref id=
"scripts"> applies to package
1256 maintainer scripts, too.
1260 You should not use
<prgn>dpkg-divert
</prgn> on a file belonging
1261 to another package without consulting the maintainer of that
1262 package first. When adding or removing diversions, package
1263 maintainer scripts must provide the
<tt>--package
</tt> flag
1264 to
<prgn>dpkg-divert
</prgn> and must not use
<tt>--local
</tt>.
1268 All packages which supply an instance of a common command
1269 name (or, in general, filename) should generally use
1270 <prgn>update-alternatives
</prgn>, so that they may be
1271 installed together. If
<prgn>update-alternatives
</prgn>
1272 is not used, then each package must use
1273 <tt>Conflicts
</tt> to ensure that other packages are
1274 de-installed. (In this case, it may be appropriate to
1275 specify a conflict against earlier versions of something
1276 that previously did not use
1277 <prgn>update-alternatives
</prgn>; this is an exception to
1278 the usual rule that versioned conflicts should be
1282 <sect1 id=
"maintscriptprompt">
1283 <heading>Prompting in maintainer scripts
</heading>
1285 Package maintainer scripts may prompt the user if
1286 necessary. Prompting must be done by communicating
1287 through a program, such as
<prgn>debconf
</prgn>, which
1288 conforms to the Debian Configuration Management
1289 Specification, version
2 or higher.
1293 Packages which are essential, or which are dependencies of
1294 essential packages, may fall back on another prompting method
1295 if no such interface is available when they are executed.
1299 The Debian Configuration Management Specification is included
1300 in the
<file>debconf_specification
</file> files in the
1301 <package>debian-policy
</package> package.
1302 It is also available from the Debian web mirrors at
1303 <tt><url name=
"/doc/packaging-manuals/debconf_specification.html"
1304 id=
"http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1308 Packages which use the Debian Configuration Management
1309 Specification may contain the additional control information
1310 files
<file>config
</file>
1311 and
<file>templates
</file>.
<file>config
</file> is an
1312 additional maintainer script used for package configuration,
1313 and
<file>templates
</file> contains templates used for user
1314 prompting. The
<prgn>config
</prgn> script might be run before
1315 the
<prgn>preinst
</prgn> script and before the package is
1316 unpacked or any of its dependencies or pre-dependencies are
1317 satisfied. Therefore it must work using only the tools
1318 present in
<em>essential
</em> packages.
<footnote>
1319 <package>Debconf
</package> or another tool that
1320 implements the Debian Configuration Management
1321 Specification will also be installed, and any
1322 versioned dependencies on it will be satisfied
1323 before preconfiguration begins.
1328 Packages which use the Debian Configuration Management
1329 Specification must allow for translation of their user-visible
1330 messages by using a gettext-based system such as the one
1331 provided by the
<package>po-debconf
</package> package.
1335 Packages should try to minimize the amount of prompting
1336 they need to do, and they should ensure that the user
1337 will only ever be asked each question once. This means
1338 that packages should try to use appropriate shared
1339 configuration files (such as
<file>/etc/papersize
</file> and
1340 <file>/etc/news/server
</file>), and shared
1341 <package>debconf
</package> variables rather than each
1342 prompting for their own list of required pieces of
1347 It also means that an upgrade should not ask the same
1348 questions again, unless the user has used
1349 <tt>dpkg --purge
</tt> to remove the package's configuration.
1350 The answers to configuration questions should be stored in an
1351 appropriate place in
<file>/etc
</file> so that the user can
1352 modify them, and how this has been done should be
1357 If a package has a vitally important piece of
1358 information to pass to the user (such as
"don't run me
1359 as I am, you must edit the following configuration files
1360 first or you risk your system emitting badly-formatted
1361 messages"), it should display this in the
1362 <prgn>config
</prgn> or
<prgn>postinst
</prgn> script and
1363 prompt the user to hit return to acknowledge the
1364 message. Copyright messages do not count as vitally
1365 important (they belong in
1366 <file>/usr/share/doc/
<var>package
</var>/copyright
</file>);
1367 neither do instructions on how to use a program (these
1368 should be in on-line documentation, where all the users
1373 Any necessary prompting should almost always be confined
1374 to the
<prgn>config
</prgn> or
<prgn>postinst
</prgn>
1375 script. If it is done in the
<prgn>postinst
</prgn>, it
1376 should be protected with a conditional so that
1377 unnecessary prompting doesn't happen if a package's
1378 installation fails and the
<prgn>postinst
</prgn> is
1379 called with
<tt>abort-upgrade
</tt>,
1380 <tt>abort-remove
</tt> or
<tt>abort-deconfigure
</tt>.
1390 <heading>Source packages
</heading>
1392 <sect id=
"standardsversion">
1393 <heading>Standards conformance
</heading>
1396 Source packages should specify the most recent version number
1397 of this policy document with which your package complied
1398 when it was last updated.
1402 This information may be used to file bug reports
1403 automatically if your package becomes too much out of date.
1407 The version is specified in the
<tt>Standards-Version
</tt>
1409 The format of the
<tt>Standards-Version
</tt> field is
1410 described in
<ref id=
"f-Standards-Version">.
1414 You should regularly, and especially if your package has
1415 become out of date, check for the newest Policy Manual
1416 available and update your package, if necessary. When your
1417 package complies with the new standards you should update the
1418 <tt>Standards-Version
</tt> source package field and
1419 release it.
<footnote>
1420 See the file
<file>upgrading-checklist
</file> for
1421 information about policy which has changed between
1422 different versions of this document.
1428 <sect id=
"pkg-relations">
1429 <heading>Package relationships
</heading>
1432 Source packages should specify which binary packages they
1433 require to be installed or not to be installed in order to
1434 build correctly. For example, if building a package
1435 requires a certain compiler, then the compiler should be
1436 specified as a build-time dependency.
1440 It is not necessary to explicitly specify build-time
1441 relationships on a minimal set of packages that are always
1442 needed to compile, link and put in a Debian package a
1443 standard
"Hello World!" program written in C or C++. The
1444 required packages are called
<em>build-essential
</em>, and
1445 an informational list can be found in
1446 <file>/usr/share/doc/build-essential/list
</file> (which is
1447 contained in the
<tt>build-essential
</tt>
1450 <list compact=
"compact">
1452 This allows maintaining the list separately
1453 from the policy documents (the list does not
1454 need the kind of control that the policy
1458 Having a separate package allows one to install
1459 the build-essential packages on a machine, as
1460 well as allowing other packages such as tasks to
1461 require installation of the build-essential
1462 packages using the depends relation.
1465 The separate package allows bug reports against
1466 the list to be categorized separately from
1467 the policy management process in the BTS.
1474 When specifying the set of build-time dependencies, one
1475 should list only those packages explicitly required by the
1476 build. It is not necessary to list packages which are
1477 required merely because some other package in the list of
1478 build-time dependencies depends on them.
<footnote>
1479 The reason for this is that dependencies change, and
1480 you should list all those packages, and
<em>only
</em>
1481 those packages that
<em>you
</em> need directly. What
1482 others need is their business. For example, if you
1483 only link against
<file>libimlib
</file>, you will need to
1484 build-depend on
<package>libimlib2-dev
</package> but
1485 not against any
<tt>libjpeg*
</tt> packages, even
1486 though
<tt>libimlib2-dev
</tt> currently depends on
1487 them: installation of
<package>libimlib2-dev
</package>
1488 will automatically ensure that all of its run-time
1489 dependencies are satisfied.
1494 If build-time dependencies are specified, it must be
1495 possible to build the package and produce working binaries
1496 on a system with only essential and build-essential
1497 packages installed and also those required to satisfy the
1498 build-time relationships (including any implied
1499 relationships). In particular, this means that version
1500 clauses should be used rigorously in build-time
1501 relationships so that one cannot produce bad or
1502 inconsistently configured packages when the relationships
1503 are properly satisfied.
1507 <ref id=
"relationships"> explains the technical details.
1512 <heading>Changes to the upstream sources
</heading>
1515 If changes to the source code are made that are not
1516 specific to the needs of the Debian system, they should be
1517 sent to the upstream authors in whatever form they prefer
1518 so as to be included in the upstream version of the
1523 If you need to configure the package differently for
1524 Debian or for Linux, and the upstream source doesn't
1525 provide a way to do so, you should add such configuration
1526 facilities (for example, a new
<prgn>autoconf
</prgn> test
1527 or
<tt>#define
</tt>) and send the patch to the upstream
1528 authors, with the default set to the way they originally
1529 had it. You can then easily override the default in your
1530 <file>debian/rules
</file> or wherever is appropriate.
1534 You should make sure that the
<prgn>configure
</prgn> utility
1535 detects the correct architecture specification string
1536 (refer to
<ref id=
"arch-spec"> for details).
1540 If you need to edit a
<prgn>Makefile
</prgn> where GNU-style
1541 <prgn>configure
</prgn> scripts are used, you should edit the
1542 <file>.in
</file> files rather than editing the
1543 <prgn>Makefile
</prgn> directly. This allows the user to
1544 reconfigure the package if necessary. You should
1545 <em>not
</em> configure the package and edit the generated
1546 <prgn>Makefile
</prgn>! This makes it impossible for someone
1547 else to later reconfigure the package without losing the
1553 <sect id=
"dpkgchangelog">
1554 <heading>Debian changelog:
<file>debian/changelog
</file></heading>
1557 Changes in the Debian version of the package should be
1558 briefly explained in the Debian changelog file
1559 <file>debian/changelog
</file>.
<footnote>
1561 Mistakes in changelogs are usually best rectified by
1562 making a new changelog entry rather than
"rewriting
1563 history" by editing old changelog entries.
1566 This includes modifications
1567 made in the Debian package compared to the upstream one
1568 as well as other changes and updates to the package.
1570 Although there is nothing stopping an author who is also
1571 the Debian maintainer from using this changelog for all
1572 their changes, it will have to be renamed if the Debian
1573 and upstream maintainers become different people. In such
1574 a case, however, it might be better to maintain the package
1575 as a non-native package.
1580 The format of the
<file>debian/changelog
</file> allows the
1581 package building tools to discover which version of the package
1582 is being built and find out other release-specific information.
1586 That format is a series of entries like this:
1588 <example compact=
"compact">
1589 <var>package
</var> (
<var>version
</var>)
<var>distribution(s)
</var>; urgency=
<var>urgency
</var>
1591 [optional blank line(s), stripped]
1593 *
<var>change details
</var>
1594 <var>more change details
</var>
1596 [blank line(s), included in output of dpkg-parsechangelog]
1598 *
<var>even more change details
</var>
1600 [optional blank line(s), stripped]
1602 --
<var>maintainer name
</var> <<var>email address
</var>><var>[two spaces]
</var> <var>date
</var>
1607 <var>package
</var> and
<var>version
</var> are the source
1608 package name and version number.
1612 <var>distribution(s)
</var> lists the distributions where
1613 this version should be installed when it is uploaded - it
1614 is copied to the
<tt>Distribution
</tt> field in the
1615 <file>.changes
</file> file. See
<ref id=
"f-Distribution">.
1619 <var>urgency
</var> is the value for the
<tt>Urgency
</tt>
1620 field in the
<file>.changes
</file> file for the upload
1621 (see
<ref id=
"f-Urgency">). It is not possible to specify
1622 an urgency containing commas; commas are used to separate
1623 <tt><var>keyword
</var>=
<var>value
</var></tt> settings in the
1624 <prgn>dpkg
</prgn> changelog format (though there is
1625 currently only one useful
<var>keyword
</var>,
1630 The change details may in fact be any series of lines
1631 starting with at least two spaces, but conventionally each
1632 change starts with an asterisk and a separating space and
1633 continuation lines are indented so as to bring them in
1634 line with the start of the text above. Blank lines may be
1635 used here to separate groups of changes, if desired.
1639 If this upload resolves bugs recorded in the Bug Tracking
1640 System (BTS), they may be automatically closed on the
1641 inclusion of this package into the Debian archive by
1642 including the string:
<tt>closes: Bug#
<var>nnnnn
</var></tt>
1643 in the change details.
<footnote>
1644 To be precise, the string should match the following
1645 Perl regular expression:
1647 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1649 Then all of the bug numbers listed will be closed by the
1650 archive maintenance script (
<prgn>katie
</prgn>) using the
1651 <var>version
</var> of the changelog entry.
1653 This information is conveyed via the
<tt>Closes
</tt> field
1654 in the
<tt>.changes
</tt> file (see
<ref id=
"f-Closes">).
1658 The maintainer name and email address used in the changelog
1659 should be the details of the person uploading
<em>this
</em>
1660 version. They are
<em>not
</em> necessarily those of the
1661 usual package maintainer. The information here will be
1662 copied to the
<tt>Changed-By
</tt> field in the
1663 <tt>.changes
</tt> file (see
<ref id=
"f-Changed-By">),
1664 and then later used to send an acknowledgement when the
1665 upload has been installed.
1669 The
<var>date
</var> has the following format
<footnote>
1670 This is the same as the format generated by
<tt>date
1672 </footnote> (compatible and with the same semantics of
1673 RFC
2822 and RFC
5322):
1674 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz
</example>
1676 <list compact=
"compact">
1678 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1681 dd is a one- or two-digit day of the month (
01-
31)
1684 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1687 <item>yyyy is the four-digit year (e.g.
2010)
</item>
1688 <item>hh is the two-digit hour (
00-
23)
</item>
1689 <item>mm is the two-digit minutes (
00-
59)
</item>
1690 <item>ss is the two-digit seconds (
00-
60)
</item>
1692 +zzzz or -zzzz is the the time zone offset from Coordinated
1693 Universal Time (UTC).
"+" indicates that the time is ahead
1694 of (i.e., east of) UTC and
"-" indicates that the time is
1695 behind (i.e., west of) UTC. The first two digits indicate
1696 the hour difference from UTC and the last two digits
1697 indicate the number of additional minutes difference from
1698 UTC. The last two digits must be in the range
00-
59.
1704 The first
"title" line with the package name must start
1705 at the left hand margin. The
"trailer" line with the
1706 maintainer and date details must be preceded by exactly
1707 one space. The maintainer details and the date must be
1708 separated by exactly two spaces.
1712 The entire changelog must be encoded in UTF-
8.
1716 For more information on placement of the changelog files
1717 within binary packages, please see
<ref id=
"changelogs">.
1721 <sect id=
"dpkgcopyright">
1722 <heading>Copyright:
<file>debian/copyright
</file></heading>
1724 Every package must be accompanied by a verbatim copy of its
1725 copyright information and distribution license in the file
1726 <file>/usr/share/doc/
<var>package
</var>/copyright
</file>
1727 (see
<ref id=
"copyrightfile"> for further details). Also see
1728 <ref id=
"pkgcopyright"> for further considerations related
1729 to copyrights for packages.
1733 <heading>Error trapping in makefiles
</heading>
1736 When
<prgn>make
</prgn> invokes a command in a makefile
1737 (including your package's upstream makefiles and
1738 <file>debian/rules
</file>), it does so using
<prgn>sh
</prgn>. This
1739 means that
<prgn>sh
</prgn>'s usual bad error handling
1740 properties apply: if you include a miniature script as one
1741 of the commands in your makefile you'll find that if you
1742 don't do anything about it then errors are not detected
1743 and
<prgn>make
</prgn> will blithely continue after
1748 Every time you put more than one shell command (this
1749 includes using a loop) in a makefile command you
1750 must make sure that errors are trapped. For
1751 simple compound commands, such as changing directory and
1752 then running a program, using
<tt>&&</tt> rather
1753 than semicolon as a command separator is sufficient. For
1754 more complex commands including most loops and
1755 conditionals you should include a separate
<tt>set -e
</tt>
1756 command at the start of every makefile command that's
1757 actually one of these miniature shell scripts.
1761 <sect id=
"timestamps">
1762 <heading>Time Stamps
</heading>
1764 Maintainers should preserve the modification times of the
1765 upstream source files in a package, as far as is reasonably
1767 The rationale is that there is some information conveyed
1768 by knowing the age of the file, for example, you could
1769 recognize that some documentation is very old by looking
1770 at the modification time, so it would be nice if the
1771 modification time of the upstream source would be
1777 <sect id=
"restrictions">
1778 <heading>Restrictions on objects in source packages
</heading>
1781 The source package may not contain any hard links
<footnote>
1783 This is not currently detected when building source
1784 packages, but only when extracting
1788 Hard links may be permitted at some point in the
1789 future, but would require a fair amount of
1792 </footnote>, device special files, sockets or setuid or
1793 setgid files.
<footnote>
1794 Setgid directories are allowed.
1799 <sect id=
"debianrules">
1800 <heading>Main building script:
<file>debian/rules
</file></heading>
1803 This file must be an executable makefile, and contains the
1804 package-specific recipes for compiling the package and
1805 building binary package(s) from the source.
1809 It must start with the line
<tt>#!/usr/bin/make -f
</tt>,
1810 so that it can be invoked by saying its name rather than
1811 invoking
<prgn>make
</prgn> explicitly. That is, invoking
1812 either of
<tt>make -f debian/rules
<em>args...
</em></tt>
1813 or
<tt>./debian/rules
<em>args...
</em></tt> must result in
1818 Since an interactive
<file>debian/rules
</file> script makes it
1819 impossible to auto-compile that package and also makes it
1820 hard for other people to reproduce the same binary
1821 package, all
<em>required targets
</em> must be
1822 non-interactive. At a minimum, required targets are the
1823 ones called by
<prgn>dpkg-buildpackage
</prgn>, namely,
1824 <em>clean
</em>,
<em>binary
</em>,
<em>binary-arch
</em>,
1825 <em>binary-indep
</em>, and
<em>build
</em>. It also follows
1826 that any target that these targets depend on must also be
1831 The targets are as follows (required unless stated otherwise):
1833 <tag><tt>build
</tt></tag>
1836 The
<tt>build
</tt> target should perform all the
1837 configuration and compilation of the package.
1838 If a package has an interactive pre-build
1839 configuration routine, the Debian source package
1840 must either be built after this has taken place (so
1841 that the binary package can be built without rerunning
1842 the configuration) or the configuration routine
1843 modified to become non-interactive. (The latter is
1844 preferable if there are architecture-specific features
1845 detected by the configuration routine.)
1849 For some packages, notably ones where the same
1850 source tree is compiled in different ways to produce
1851 two binary packages, the
<tt>build
</tt> target
1852 does not make much sense. For these packages it is
1853 good enough to provide two (or more) targets
1854 (
<tt>build-a
</tt> and
<tt>build-b
</tt> or whatever)
1855 for each of the ways of building the package, and a
1856 <tt>build
</tt> target that does nothing. The
1857 <tt>binary
</tt> target will have to build the
1858 package in each of the possible ways and make the
1859 binary package out of each.
1863 The
<tt>build
</tt> target must not do anything
1864 that might require root privilege.
1868 The
<tt>build
</tt> target may need to run the
1869 <tt>clean
</tt> target first - see below.
1873 When a package has a configuration and build routine
1874 which takes a long time, or when the makefiles are
1875 poorly designed, or when
<tt>build
</tt> needs to
1876 run
<tt>clean
</tt> first, it is a good idea to
1877 <tt>touch build
</tt> when the build process is
1878 complete. This will ensure that if
<tt>debian/rules
1879 build
</tt> is run again it will not rebuild the whole
1881 Another common way to do this is for
<tt>build
</tt>
1882 to depend on
<prgn>build-stamp
</prgn> and to do
1883 nothing else, and for the
<prgn>build-stamp
</prgn>
1884 target to do the building and to
<tt>touch
1885 build-stamp
</tt> on completion. This is
1886 especially useful if the build routine creates a
1887 file or directory called
<tt>build
</tt>; in such a
1888 case,
<tt>build
</tt> will need to be listed as
1889 a phony target (i.e., as a dependency of the
1890 <tt>.PHONY
</tt> target). See the documentation of
1891 <prgn>make
</prgn> for more information on phony
1897 <tag><tt>build-arch
</tt> (optional),
1898 <tt>build-indep
</tt> (optional)
1902 A package may also provide both of the targets
1903 <tt>build-arch
</tt> and
<tt>build-indep
</tt>.
1904 The
<tt>build-arch
</tt> target, if provided, should
1905 perform all the configuration and compilation required for
1906 producing all architecture-dependant binary packages
1907 (those packages for which the body of the
1908 <tt>Architecture
</tt> field in
<tt>debian/control
</tt> is
1909 not
<tt>all
</tt>). Similarly, the
<tt>build-indep
</tt>
1910 target, if provided, should perform all the configuration
1911 and compilation required for producing all
1912 architecture-independent binary packages (those packages
1913 for which the body of the
<tt>Architecture
</tt> field
1914 in
<tt>debian/control
</tt> is
<tt>all
</tt>).
1915 The
<tt>build
</tt> target should depend on those of the
1916 targets
<tt>build-arch
</tt> and
<tt>build-indep
</tt> that
1917 are provided in the rules file.
<footnote>
1918 The intent of this split is so that binary-only builds
1919 need not install the dependencies required for
1920 the
<tt>build-indep
</tt> target. However, this is not
1921 yet used in practice since
<tt>dpkg-buildpackage
1922 -B
</tt>, and therefore the autobuilders,
1923 invoke
<tt>build
</tt> rather than
<tt>build-arch
</tt>
1924 due to the difficulties in determining whether the
1925 optional
<tt>build-arch
</tt> target exists.
1930 If one or both of the targets
<tt>build-arch
</tt> and
1931 <tt>build-indep
</tt> are not provided, then invoking
1932 <file>debian/rules
</file> with one of the not-provided
1933 targets as arguments should produce a exit status code
1934 of
2. Usually this is provided automatically by make
1935 if the target is missing.
1939 The
<tt>build-arch
</tt> and
<tt>build-indep
</tt> targets
1940 must not do anything that might require root privilege.
1944 <tag><tt>binary
</tt>,
<tt>binary-arch
</tt>,
1945 <tt>binary-indep
</tt>
1949 The
<tt>binary
</tt> target must be all that is
1950 necessary for the user to build the binary package(s)
1951 produced from this source package. It is
1952 split into two parts:
<prgn>binary-arch
</prgn> builds
1953 the binary packages which are specific to a particular
1954 architecture, and
<tt>binary-indep
</tt> builds
1955 those which are not.
1958 <tt>binary
</tt> may be (and commonly is) a target with
1959 no commands which simply depends on
1960 <tt>binary-arch
</tt> and
<tt>binary-indep
</tt>.
1963 Both
<tt>binary-*
</tt> targets should depend on the
1964 <tt>build
</tt> target, or on the appropriate
1965 <tt>build-arch
</tt> or
<tt>build-indep
</tt> target, if
1966 provided, so that the package is built if it has not
1967 been already. It should then create the relevant
1968 binary package(s), using
<prgn>dpkg-gencontrol
</prgn> to
1969 make their control files and
<prgn>dpkg-deb
</prgn> to
1970 build them and place them in the parent of the top
1975 Both the
<tt>binary-arch
</tt> and
1976 <tt>binary-indep
</tt> targets
<em>must
</em> exist.
1977 If one of them has nothing to do (which will always be
1978 the case if the source generates only a single binary
1979 package, whether architecture-dependent or not), it
1980 must still exist and must always succeed.
1984 The
<tt>binary
</tt> targets must be invoked as
1986 The
<prgn>fakeroot
</prgn> package often allows one
1987 to build a package correctly even without being
1993 <tag><tt>clean
</tt></tag>
1996 This must undo any effects that the
<tt>build
</tt>
1997 and
<tt>binary
</tt> targets may have had, except
1998 that it should leave alone any output files created in
1999 the parent directory by a run of a
<tt>binary
</tt>
2004 If a
<tt>build
</tt> file is touched at the end of
2005 the
<tt>build
</tt> target, as suggested above, it
2006 should be removed as the first action that
2007 <tt>clean
</tt> performs, so that running
2008 <tt>build
</tt> again after an interrupted
2009 <tt>clean
</tt> doesn't think that everything is
2014 The
<tt>clean
</tt> target may need to be
2015 invoked as root if
<tt>binary
</tt> has been
2016 invoked since the last
<tt>clean
</tt>, or if
2017 <tt>build
</tt> has been invoked as root (since
2018 <tt>build
</tt> may create directories, for
2023 <tag><tt>get-orig-source
</tt> (optional)
</tag>
2026 This target fetches the most recent version of the
2027 original source package from a canonical archive site
2028 (via FTP or WWW, for example), does any necessary
2029 rearrangement to turn it into the original source
2030 tar file format described below, and leaves it in the
2035 This target may be invoked in any directory, and
2036 should take care to clean up any temporary files it
2041 This target is optional, but providing it if
2042 possible is a good idea.
2046 <tag><tt>patch
</tt> (optional)
</tag>
2049 This target performs whatever additional actions are
2050 required to make the source ready for editing (unpacking
2051 additional upstream archives, applying patches, etc.).
2052 It is recommended to be implemented for any package where
2053 <tt>dpkg-source -x
</tt> does not result in source ready
2054 for additional modification. See
2055 <ref id=
"readmesource">.
2061 The
<tt>build
</tt>,
<tt>binary
</tt> and
2062 <tt>clean
</tt> targets must be invoked with the current
2063 directory being the package's top-level directory.
2068 Additional targets may exist in
<file>debian/rules
</file>,
2069 either as published or undocumented interfaces or for the
2070 package's internal use.
2074 The architectures we build on and build for are determined
2075 by
<prgn>make
</prgn> variables using the utility
2076 <qref id=
"pkg-dpkg-architecture"><prgn>dpkg-architecture
</prgn></qref>.
2077 You can determine the
2078 Debian architecture and the GNU style architecture
2079 specification string for the build machine (the machine type
2080 we are building on) as well as for the host machine (the
2081 machine type we are building for). Here is a list of
2082 supported
<prgn>make
</prgn> variables:
2083 <list compact=
"compact">
2085 <tt>DEB_*_ARCH
</tt> (the Debian architecture)
2088 <tt>DEB_*_ARCH_CPU
</tt> (the Debian CPU name)
2091 <tt>DEB_*_ARCH_OS
</tt> (the Debian System name)
2094 <tt>DEB_*_GNU_TYPE
</tt> (the GNU style architecture
2095 specification string)
2098 <tt>DEB_*_GNU_CPU
</tt> (the CPU part of
2099 <tt>DEB_*_GNU_TYPE
</tt>)
2102 <tt>DEB_*_GNU_SYSTEM
</tt> (the System part of
2103 <tt>DEB_*_GNU_TYPE
</tt>)
2105 where
<tt>*
</tt> is either
<tt>BUILD
</tt> for specification of
2106 the build machine or
<tt>HOST
</tt> for specification of the
2111 Backward compatibility can be provided in the rules file
2112 by setting the needed variables to suitable default
2113 values; please refer to the documentation of
2114 <prgn>dpkg-architecture
</prgn> for details.
2118 It is important to understand that the
<tt>DEB_*_ARCH
</tt>
2119 string only determines which Debian architecture we are
2120 building on or for. It should not be used to get the CPU
2121 or system information; the
<tt>DEB_*_ARCH_CPU
</tt> and
2122 <tt>DEB_*_ARCH_OS
</tt> variables should be used for that.
2123 GNU style variables should generally only be used with upstream
2127 <sect1 id=
"debianrules-options">
2128 <heading><file>debian/rules
</file> and
2129 <tt>DEB_BUILD_OPTIONS
</tt></heading>
2132 Supporting the standardized environment variable
2133 <tt>DEB_BUILD_OPTIONS
</tt> is recommended. This variable can
2134 contain several flags to change how a package is compiled and
2135 built. Each flag must be in the form
<var>flag
</var> or
2136 <var>flag
</var>=
<var>options
</var>. If multiple flags are
2137 given, they must be separated by whitespace.
<footnote>
2138 Some packages support any delimiter, but whitespace is the
2139 easiest to parse inside a makefile and avoids ambiguity with
2140 flag values that contain commas.
2142 <var>flag
</var> must start with a lowercase letter
2143 (
<tt>a-z
</tt>) and consist only of lowercase letters,
2144 numbers (
<tt>0-
9</tt>), and the characters
2145 <tt>-
</tt> and
<tt>_
</tt> (hyphen and underscore).
2146 <var>options
</var> must not contain whitespace. The same
2147 tag should not be given multiple times with conflicting
2148 values. Package maintainers may assume that
2149 <tt>DEB_BUILD_OPTIONS
</tt> will not contain conflicting tags.
2153 The meaning of the following tags has been standardized:
2157 This tag says to not run any build-time test suite
2158 provided by the package.
2162 The presence of this tag means that the package should
2163 be compiled with a minimum of optimization. For C
2164 programs, it is best to add
<tt>-O0
</tt> to
2165 <tt>CFLAGS
</tt> (although this is usually the default).
2166 Some programs might fail to build or run at this level
2167 of optimization; it may be necessary to use
2168 <tt>-O1
</tt>, for example.
2172 This tag means that the debugging symbols should not be
2173 stripped from the binary during installation, so that
2174 debugging information may be included in the package.
2176 <tag>parallel=n
</tag>
2178 This tag means that the package should be built using up
2179 to
<tt>n
</tt> parallel processes if the package build
2180 system supports this.
<footnote>
2181 Packages built with
<tt>make
</tt> can often implement
2182 this by passing the
<tt>-j
</tt><var>n
</var> option to
2185 If the package build system does not support parallel
2186 builds, this string must be ignored. If the package
2187 build system only supports a lower level of concurrency
2188 than
<var>n
</var>, the package should be built using as
2189 many parallel processes as the package build system
2190 supports. It is up to the package maintainer to decide
2191 whether the package build times are long enough and the
2192 package build system is robust enough to make supporting
2193 parallel builds worthwhile.
2199 Unknown flags must be ignored by
<file>debian/rules
</file>.
2203 The following makefile snippet is an example of how one may
2204 implement the build options; you will probably have to
2205 massage this example in order to make it work for your
2207 <example compact=
"compact">
2210 INSTALL_FILE = $(INSTALL) -p -o root -g root -m
644
2211 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m
755
2212 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m
755
2213 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m
755
2215 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2220 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2221 INSTALL_PROGRAM += -s
2223 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2224 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2225 MAKEFLAGS += -j$(NUMJOBS)
2230 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2231 # Code to run the package test suite.
2238 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2239 <sect id=
"substvars">
2240 <heading>Variable substitutions:
<file>debian/substvars
</file></heading>
2243 When
<prgn>dpkg-gencontrol
</prgn>,
2244 <prgn>dpkg-genchanges
</prgn> and
<prgn>dpkg-source
</prgn>
2245 generate control files, they perform variable substitutions
2246 on their output just before writing it. Variable
2247 substitutions have the form
<tt>${
<var>variable
</var>}
</tt>.
2248 The optional file
<file>debian/substvars
</file> contains
2249 variable substitutions to be used; variables can also be set
2250 directly from
<file>debian/rules
</file> using the
<tt>-V
</tt>
2251 option to the source packaging commands, and certain
2252 predefined variables are also available.
2256 The
<file>debian/substvars
</file> file is usually generated and
2257 modified dynamically by
<file>debian/rules
</file> targets, in
2258 which case it must be removed by the
<tt>clean
</tt> target.
2262 See
<manref name=
"deb-substvars" section=
"5"> for full
2263 details about source variable substitutions, including the
2264 format of
<file>debian/substvars
</file>.
</p>
2267 <sect id=
"debianwatch">
2268 <heading>Optional upstream source location:
<file>debian/watch
</file></heading>
2271 This is an optional, recommended configuration file for the
2272 <tt>uscan
</tt> utility which defines how to automatically scan
2273 ftp or http sites for newly available updates of the
2274 package. This is used
2275 by
<url id=
"http://dehs.alioth.debian.org/"> and other Debian QA
2276 tools to help with quality control and maintenance of the
2277 distribution as a whole.
2282 <sect id=
"debianfiles">
2283 <heading>Generated files list:
<file>debian/files
</file></heading>
2286 This file is not a permanent part of the source tree; it
2287 is used while building packages to record which files are
2288 being generated.
<prgn>dpkg-genchanges
</prgn> uses it
2289 when it generates a
<file>.changes
</file> file.
2293 It should not exist in a shipped source package, and so it
2294 (and any backup files or temporary files such as
2295 <file>files.new
</file><footnote>
2296 <file>files.new
</file> is used as a temporary file by
2297 <prgn>dpkg-gencontrol
</prgn> and
2298 <prgn>dpkg-distaddfile
</prgn> - they write a new
2299 version of
<tt>files
</tt> here before renaming it,
2300 to avoid leaving a corrupted copy if an error
2302 </footnote>) should be removed by the
2303 <tt>clean
</tt> target. It may also be wise to
2304 ensure a fresh start by emptying or removing it at the
2305 start of the
<tt>binary
</tt> target.
2309 When
<prgn>dpkg-gencontrol
</prgn> is run for a binary
2310 package, it adds an entry to
<file>debian/files
</file> for the
2311 <file>.deb
</file> file that will be created when
<tt>dpkg-deb
2312 --build
</tt> is run for that binary package. So for most
2313 packages all that needs to be done with this file is to
2314 delete it in the
<tt>clean
</tt> target.
2318 If a package upload includes files besides the source
2319 package and any binary packages whose control files were
2320 made with
<prgn>dpkg-gencontrol
</prgn> then they should be
2321 placed in the parent of the package's top-level directory
2322 and
<prgn>dpkg-distaddfile
</prgn> should be called to add
2323 the file to the list in
<file>debian/files
</file>.
</p>
2326 <sect id=
"embeddedfiles">
2327 <heading>Convenience copies of code
</heading>
2330 Some software packages include in their distribution convenience
2331 copies of code from other software packages, generally so that
2332 users compiling from source don't have to download multiple
2333 packages. Debian packages should not make use of these
2334 convenience copies unless the included package is explicitly
2335 intended to be used in this way.
<footnote>
2336 For example, parts of the GNU build system work like this.
2338 If the included code is already in the Debian archive in the
2339 form of a library, the Debian packaging should ensure that
2340 binary packages reference the libraries already in Debian and
2341 the convenience copy is not used. If the included code is not
2342 already in Debian, it should be packaged separately as a
2343 prerequisite if possible.
2345 Having multiple copies of the same code in Debian is
2346 inefficient, often creates either static linking or shared
2347 library conflicts, and, most importantly, increases the
2348 difficulty of handling security vulnerabilities in the
2354 <sect id=
"readmesource">
2355 <heading>Source package handling:
2356 <file>debian/README.source
</file></heading>
2359 If running
<prgn>dpkg-source -x
</prgn> on a source package
2360 doesn't produce the source of the package, ready for editing,
2361 and allow one to make changes and run
2362 <prgn>dpkg-buildpackage
</prgn> to produce a modified package
2363 without taking any additional steps, creating a
2364 <file>debian/README.source
</file> documentation file is
2365 recommended. This file should explain how to do all of the
2368 <item>Generate the fully patched source, in a form ready for
2369 editing, that would be built to create Debian
2370 packages. Doing this with a
<tt>patch
</tt> target in
2371 <file>debian/rules
</file> is recommended; see
2372 <ref id=
"debianrules">.
</item>
2373 <item>Modify the source and save those modifications so that
2374 they will be applied when building the package.
</item>
2375 <item>Remove source modifications that are currently being
2376 applied when building the package.
</item>
2377 <item>Optionally, document what steps are necessary to
2378 upgrade the Debian source package to a new upstream version,
2379 if applicable.
</item>
2381 This explanation should include specific commands and mention
2382 any additional required Debian packages. It should not assume
2383 familiarity with any specific Debian packaging system or patch
2388 This explanation may refer to a documentation file installed by
2389 one of the package's build dependencies provided that the
2390 referenced documentation clearly explains these tasks and is not
2391 a general reference manual.
2395 <file>debian/README.source
</file> may also include any other
2396 information that would be helpful to someone modifying the
2397 source package. Even if the package doesn't fit the above
2398 description, maintainers are encouraged to document in a
2399 <file>debian/README.source
</file> file any source package with a
2400 particularly complex or unintuitive source layout or build
2401 system (for example, a package that builds the same source
2402 multiple times to generate different binary packages).
2408 <chapt id=
"controlfields">
2409 <heading>Control files and their fields
</heading>
2412 The package management system manipulates data represented in
2413 a common format, known as
<em>control data
</em>, stored in
2414 <em>control files
</em>.
2415 Control files are used for source packages, binary packages and
2416 the
<file>.changes
</file> files which control the installation
2417 of uploaded files
<footnote>
2418 <prgn>dpkg
</prgn>'s internal databases are in a similar
2423 <sect id=
"controlsyntax">
2424 <heading>Syntax of control files
</heading>
2427 A control file consists of one or more paragraphs of
2429 The paragraphs are also sometimes referred to as stanzas.
2431 The paragraphs are separated by blank lines. Some control
2432 files allow only one paragraph; others allow several, in
2433 which case each paragraph usually refers to a different
2434 package. (For example, in source packages, the first
2435 paragraph refers to the source package, and later paragraphs
2436 refer to binary packages generated from the source.)
2440 Each paragraph consists of a series of data fields; each
2441 field consists of the field name, followed by a colon and
2442 then the data/value associated with that field. It ends at
2443 the end of the (logical) line. Horizontal whitespace
2444 (spaces and tabs) may occur immediately before or after the
2445 value and is ignored there; it is conventional to put a
2446 single space after the colon. For example, a field might
2448 <example compact=
"compact">
2451 the field name is
<tt>Package
</tt> and the field value
2456 A paragraph must not contain more than one instance of a
2457 particular field name.
2461 Many fields' values may span several lines; in this case
2462 each continuation line must start with a space or a tab.
2463 Any trailing spaces or tabs at the end of individual
2464 lines of a field value are ignored.
2468 In fields where it is specified that lines may not wrap,
2469 only a single line of data is allowed and whitespace is not
2470 significant in a field body. Whitespace must not appear
2471 inside names (of packages, architectures, files or anything
2472 else) or version numbers, or between the characters of
2473 multi-character version relationships.
2477 Field names are not case-sensitive, but it is usual to
2478 capitalize the field names using mixed case as shown below.
2479 Field values are case-sensitive unless the description of the
2480 field says otherwise.
2484 Blank lines, or lines consisting only of spaces and tabs,
2485 are not allowed within field values or between fields - that
2486 would mean a new paragraph.
2490 All control files must be encoded in UTF-
8.
2494 <sect id=
"sourcecontrolfiles">
2495 <heading>Source package control files --
<file>debian/control
</file></heading>
2498 The
<file>debian/control
</file> file contains the most vital
2499 (and version-independent) information about the source package
2500 and about the binary packages it creates.
2504 The first paragraph of the control file contains information about
2505 the source package in general. The subsequent sets each describe a
2506 binary package that the source tree builds.
2510 The fields in the general paragraph (the first one, for the source
2513 <list compact=
"compact">
2514 <item><qref id=
"f-Source"><tt>Source
</tt></qref> (mandatory)
</item>
2515 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2516 <item><qref id=
"f-Uploaders"><tt>Uploaders
</tt></qref></item>
2517 <item><qref id=
"f-Section"><tt>Section
</tt></qref> (recommended)
</item>
2518 <item><qref id=
"f-Priority"><tt>Priority
</tt></qref> (recommended)
</item>
2519 <item><qref id=
"sourcebinarydeps"><tt>Build-Depends
</tt> et al
</qref></item>
2520 <item><qref id=
"f-Standards-Version"><tt>Standards-Version
</tt></qref> (recommended)
</item>
2521 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2526 The fields in the binary package paragraphs are:
2528 <list compact=
"compact">
2529 <item><qref id=
"f-Package"><tt>Package
</tt></qref> (mandatory)
</item>
2530 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref> (mandatory)
</item>
2531 <item><qref id=
"f-Section"><tt>Section
</tt></qref> (recommended)
</item>
2532 <item><qref id=
"f-Priority"><tt>Priority
</tt></qref> (recommended)
</item>
2533 <item><qref id=
"f-Essential"><tt>Essential
</tt></qref></item>
2534 <item><qref id=
"binarydeps"><tt>Depends
</tt> et al
</qref></item>
2535 <item><qref id=
"f-Description"><tt>Description
</tt></qref> (mandatory)
</item>
2536 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2541 The syntax and semantics of the fields are described below.
2545 These fields are used by
<prgn>dpkg-gencontrol
</prgn> to
2546 generate control files for binary packages (see below), by
2547 <prgn>dpkg-genchanges
</prgn> to generate the
2548 <file>.changes
</file> file to accompany the upload, and by
2549 <prgn>dpkg-source
</prgn> when it creates the
2550 <file>.dsc
</file> source control file as part of a source
2551 archive. Many fields are permitted to span multiple lines in
2552 <file>debian/control
</file> but not in any other control
2553 file. These tools are responsible for removing the line
2554 breaks from such fields when using fields from
2555 <file>debian/control
</file> to generate other control files.
2559 The fields here may contain variable references - their
2560 values will be substituted by
<prgn>dpkg-gencontrol
</prgn>,
2561 <prgn>dpkg-genchanges
</prgn> or
<prgn>dpkg-source
</prgn>
2562 when they generate output control files.
2563 See
<ref id=
"substvars"> for details.
2567 In addition to the control file syntax described
<qref
2568 id=
"controlsyntax">above
</qref>, this file may also contain
2569 comment lines starting with
<tt>#
</tt> without any preceding
2570 whitespace. All such lines are ignored, even in the middle of
2571 continuation lines for a multiline field, and do not end a
2577 <sect id=
"binarycontrolfiles">
2578 <heading>Binary package control files --
<file>DEBIAN/control
</file></heading>
2581 The
<file>DEBIAN/control
</file> file contains the most vital
2582 (and version-dependent) information about a binary package. It
2583 consists of a single paragraph.
2587 The fields in this file are:
2589 <list compact=
"compact">
2590 <item><qref id=
"f-Package"><tt>Package
</tt></qref> (mandatory)
</item>
2591 <item><qref id=
"f-Source"><tt>Source
</tt></qref></item>
2592 <item><qref id=
"f-Version"><tt>Version
</tt></qref> (mandatory)
</item>
2593 <item><qref id=
"f-Section"><tt>Section
</tt></qref> (recommended)
</item>
2594 <item><qref id=
"f-Priority"><tt>Priority
</tt></qref> (recommended)
</item>
2595 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref> (mandatory)
</item>
2596 <item><qref id=
"f-Essential"><tt>Essential
</tt></qref></item>
2597 <item><qref id=
"binarydeps"><tt>Depends
</tt> et al
</qref></item>
2598 <item><qref id=
"f-Installed-Size"><tt>Installed-Size
</tt></qref></item>
2599 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2600 <item><qref id=
"f-Description"><tt>Description
</tt></qref> (mandatory)
</item>
2601 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2606 <sect id=
"debiansourcecontrolfiles">
2607 <heading>Debian source control files --
<tt>.dsc
</tt></heading>
2610 This file consists of a single paragraph, possibly surrounded by
2611 a PGP signature. The fields of that paragraph are listed below.
2612 Their syntax is described above, in
<ref id=
"pkg-controlfields">.
2614 <list compact=
"compact">
2615 <item><qref id=
"f-Format"><tt>Format
</tt></qref> (mandatory)
</item>
2616 <item><qref id=
"f-Source"><tt>Source
</tt></qref> (mandatory)
</item>
2617 <item><qref id=
"f-Binary"><tt>Binary
</tt></qref></item>
2618 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref></item>
2619 <item><qref id=
"f-Version"><tt>Version
</tt></qref> (mandatory)
</item>
2620 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2621 <item><qref id=
"f-Uploaders"><tt>Uploaders
</tt></qref></item>
2622 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2623 <item><qref id=
"f-Standards-Version"><tt>Standards-Version
</tt></qref> (recommended)
</item>
2624 <item><qref id=
"sourcebinarydeps"><tt>Build-Depends
</tt> et al
</qref></item>
2625 <item><qref id=
"f-Checksums"><tt>Checksums-Sha1
</tt>
2626 and
<tt>Checksums-Sha256
</tt></qref> (recommended)
</item>
2627 <item><qref id=
"f-Files"><tt>Files
</tt></qref> (mandatory)
</item>
2632 The source package control file is generated by
2633 <prgn>dpkg-source
</prgn> when it builds the source
2634 archive, from other files in the source package,
2635 described above. When unpacking, it is checked against
2636 the files and directories in the other parts of the
2642 <sect id=
"debianchangesfiles">
2643 <heading>Debian changes files --
<file>.changes
</file></heading>
2646 The
<file>.changes
</file> files are used by the Debian archive
2647 maintenance software to process updates to packages. They
2648 consist of a single paragraph, possibly surrounded by a PGP
2649 signature. That paragraph contains information from the
2650 <file>debian/control
</file> file and other data about the
2651 source package gathered via
<file>debian/changelog
</file>
2652 and
<file>debian/rules
</file>.
2656 <file>.changes
</file> files have a format version that is
2657 incremented whenever the documented fields or their meaning
2658 change. This document describes format
&changesversion;.
2662 The fields in this file are:
2664 <list compact=
"compact">
2665 <item><qref id=
"f-Format"><tt>Format
</tt></qref> (mandatory)
</item>
2666 <item><qref id=
"f-Date"><tt>Date
</tt></qref> (mandatory)
</item>
2667 <item><qref id=
"f-Source"><tt>Source
</tt></qref> (mandatory)
</item>
2668 <item><qref id=
"f-Binary"><tt>Binary
</tt></qref> (mandatory)
</item>
2669 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref> (mandatory)
</item>
2670 <item><qref id=
"f-Version"><tt>Version
</tt></qref> (mandatory)
</item>
2671 <item><qref id=
"f-Distribution"><tt>Distribution
</tt></qref> (mandatory)
</item>
2672 <item><qref id=
"f-Urgency"><tt>Urgency
</tt></qref> (recommended)
</item>
2673 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2674 <item><qref id=
"f-Changed-By"><tt>Changed-By
</tt></qref></item>
2675 <item><qref id=
"f-Description"><tt>Description
</tt></qref> (mandatory)
</item>
2676 <item><qref id=
"f-Closes"><tt>Closes
</tt></qref></item>
2677 <item><qref id=
"f-Changes"><tt>Changes
</tt></qref> (mandatory)
</item>
2678 <item><qref id=
"f-Checksums"><tt>Checksums-Sha1
</tt>
2679 and
<tt>Checksums-Sha256
</tt></qref> (recommended)
</item>
2680 <item><qref id=
"f-Files"><tt>Files
</tt></qref> (mandatory)
</item>
2685 <sect id=
"controlfieldslist">
2686 <heading>List of fields
</heading>
2688 <sect1 id=
"f-Source">
2689 <heading><tt>Source
</tt></heading>
2692 This field identifies the source package name.
2696 In
<file>debian/control
</file> or a
<file>.dsc
</file> file,
2697 this field must contain only the name of the source package.
2701 In a binary package control file or a
<file>.changes
</file>
2702 file, the source package name may be followed by a version
2703 number in parentheses
<footnote>
2704 It is customary to leave a space after the package name
2705 if a version number is specified.
2707 This version number may be omitted (and is, by
2708 <prgn>dpkg-gencontrol
</prgn>) if it has the same value as
2709 the
<tt>Version
</tt> field of the binary package in
2710 question. The field itself may be omitted from a binary
2711 package control file when the source package has the same
2712 name and version as the binary package.
2716 Package names (both source and binary,
2717 see
<ref id=
"f-Package">) must consist only of lower case
2718 letters (
<tt>a-z
</tt>), digits (
<tt>0-
9</tt>), plus
2719 (
<tt>+
</tt>) and minus (
<tt>-
</tt>) signs, and periods
2720 (
<tt>.
</tt>). They must be at least two characters long and
2721 must start with an alphanumeric character.
2725 <sect1 id=
"f-Maintainer">
2726 <heading><tt>Maintainer
</tt></heading>
2729 The package maintainer's name and email address. The name
2730 must come first, then the email address inside angle
2731 brackets
<tt><></tt> (in RFC822 format).
2735 If the maintainer's name contains a full stop then the
2736 whole field will not work directly as an email address due
2737 to a misfeature in the syntax specified in RFC822; a
2738 program using this field as an address must check for this
2739 and correct the problem if necessary (for example by
2740 putting the name in round brackets and moving it to the
2741 end, and bringing the email address forward).
2745 See
<ref id=
"maintainer"> for additional requirements and
2746 information about package maintainers.
2750 <sect1 id=
"f-Uploaders">
2751 <heading><tt>Uploaders
</tt></heading>
2754 List of the names and email addresses of co-maintainers of the
2755 package, if any. If the package has other maintainers besides
2756 the one named in the
<qref id=
"f-Maintainer">Maintainer
2757 field
</qref>, their names and email addresses should be listed
2758 here. The format of each entry is the same as that of the
2759 Maintainer field, and multiple entries must be comma
2764 This is normally an optional field, but if
2765 the
<tt>Maintainer
</tt> control field names a group of people
2766 and a shared email address, the
<tt>Uploaders
</tt> field must
2767 be present and must contain at least one human with their
2768 personal email address.
2772 Any parser that interprets the Uploaders field in
2773 <file>debian/control
</file> must permit it to span multiple
2774 lines. Line breaks in an Uploaders field that spans multiple
2775 lines are not significant and the semantics of the field are
2776 the same as if the line breaks had not been present.
2780 <sect1 id=
"f-Changed-By">
2781 <heading><tt>Changed-By
</tt></heading>
2784 The name and email address of the person who prepared this
2785 version of the package, usually a maintainer. The syntax is
2786 the same as for the
<qref id=
"f-Maintainer">Maintainer
2791 <sect1 id=
"f-Section">
2792 <heading><tt>Section
</tt></heading>
2795 This field specifies an application area into which the package
2796 has been classified. See
<ref id=
"subsections">.
2800 When it appears in the
<file>debian/control
</file> file,
2801 it gives the value for the subfield of the same name in
2802 the
<tt>Files
</tt> field of the
<file>.changes
</file> file.
2803 It also gives the default for the same field in the binary
2808 <sect1 id=
"f-Priority">
2809 <heading><tt>Priority
</tt></heading>
2812 This field represents how important it is that the user
2813 have the package installed. See
<ref id=
"priorities">.
2817 When it appears in the
<file>debian/control
</file> file,
2818 it gives the value for the subfield of the same name in
2819 the
<tt>Files
</tt> field of the
<file>.changes
</file> file.
2820 It also gives the default for the same field in the binary
2825 <sect1 id=
"f-Package">
2826 <heading><tt>Package
</tt></heading>
2829 The name of the binary package.
2833 Binary package names must follow the same syntax and
2834 restrictions as source package names. See
<ref id=
"f-Source">
2839 <sect1 id=
"f-Architecture">
2840 <heading><tt>Architecture
</tt></heading>
2843 Depending on context and the control file used, the
2844 <tt>Architecture
</tt> field can include the following sets of
2848 A unique single word identifying a Debian machine
2849 architecture as described in
<ref id=
"arch-spec">.
2852 An architecture wildcard identifying a set of Debian
2853 machine architectures, see
<ref id=
"arch-wildcard-spec">.
2854 <tt>any
</tt> matches all Debian machine architectures
2855 and is the most frequently used.
2858 <tt>all
</tt>, which indicates an
2859 architecture-independent package.
2862 <tt>source
</tt>, which indicates a source package.
2868 In the main
<file>debian/control
</file> file in the source
2869 package, this field may contain the special
2870 value
<tt>all
</tt>, the special architecture
2871 wildcard
<tt>any
</tt>, or a list of specific and wildcard
2872 architectures separated by spaces. If
<tt>all
</tt>
2873 or
<tt>any
</tt> appears, that value must be the entire
2874 contents of the field. Most packages will use
2875 either
<tt>all
</tt> or
<tt>any
</tt>.
2879 Specifying a specific list of architectures indicates that the
2880 source will build an architecture-dependent package only on
2881 architectures included in the list. Specifying a list of
2882 architecture wildcards indicates that the source will build an
2883 architecture-dependent package on only those architectures
2884 that match any of the specified architecture wildcards.
2885 Specifying a list of architectures or architecture wildcards
2886 other than
<tt>any
</tt> is for the minority of cases where a
2887 program is not portable or is not useful on some
2888 architectures. Where possible, the program should be made
2893 In the source package control file
<file>.dsc
</file>, this
2894 field may contain either the architecture
2895 wildcard
<tt>any
</tt> or a list of architectures and
2896 architecture wildcards separated by spaces. If a list is
2897 given, it may include (or consist solely of) the special
2898 value
<tt>all
</tt>. In other words, in
<file>.dsc
</file>
2899 files unlike the
<file>debian/control
</file>,
<tt>all
</tt> may
2900 occur in combination with specific architectures.
2901 The
<tt>Architecture
</tt> field in the source package control
2902 file
<file>.dsc
</file> is generally constructed from
2903 the
<tt>Architecture
</tt> fields in
2904 the
<file>debian/control
</file> in the source package.
2908 Specifying
<tt>any
</tt> indicates that the source package
2909 isn't dependent on any particular architecture and should
2910 compile fine on any one. The produced binary package(s)
2911 will either be specific to whatever the current build
2912 architecture is or will be architecture-independent.
2916 Specifying only
<tt>all
</tt> indicates that the source package
2917 will only build architecture-independent packages. If this is
2918 the case,
<tt>all
</tt> must be used rather than
<tt>any
</tt>;
2919 <tt>any
</tt> implies that the source package will build at
2920 least one architecture-dependent package.
2924 Specifying a list of architectures or architecture wildcards
2925 indicates that the source will build an architecture-dependent
2926 package, and will only work correctly on the listed or
2927 matching architectures. If the source package also builds at
2928 least one architecture-independent package,
<tt>all
</tt> will
2929 also be included in the list.
2933 In a
<file>.changes
</file> file, the
<tt>Architecture
</tt>
2934 field lists the architecture(s) of the package(s) currently
2935 being uploaded. This will be a list; if the source for the
2936 package is also being uploaded, the special
2937 entry
<tt>source
</tt> is also present.
<tt>all
</tt> will be
2938 present if any architecture-independent packages are being
2939 uploaded. Architecture wildcards such as
<tt>any
</tt> must
2940 never occur in the
<tt>Architecture
</tt> field in
2941 the
<file>.changes
</file> file.
2945 See
<ref id=
"debianrules"> for information on how to get
2946 the architecture for the build process.
2950 <sect1 id=
"f-Essential">
2951 <heading><tt>Essential
</tt></heading>
2954 This is a boolean field which may occur only in the
2955 control file of a binary package or in a per-package fields
2956 paragraph of a main source control data file.
2960 If set to
<tt>yes
</tt> then the package management system
2961 will refuse to remove the package (upgrading and replacing
2962 it is still possible). The other possible value is
<tt>no
</tt>,
2963 which is the same as not having the field at all.
2968 <heading>Package interrelationship fields:
2969 <tt>Depends
</tt>,
<tt>Pre-Depends
</tt>,
2970 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
2971 <tt>Breaks
</tt>,
<tt>Conflicts
</tt>,
2972 <tt>Provides
</tt>,
<tt>Replaces
</tt>,
<tt>Enhances
</tt>
2976 These fields describe the package's relationships with
2977 other packages. Their syntax and semantics are described
2978 in
<ref id=
"relationships">.
</p>
2981 <sect1 id=
"f-Standards-Version">
2982 <heading><tt>Standards-Version
</tt></heading>
2985 The most recent version of the standards (the policy
2986 manual and associated texts) with which the package
2991 The version number has four components: major and minor
2992 version number and major and minor patch level. When the
2993 standards change in a way that requires every package to
2994 change the major number will be changed. Significant
2995 changes that will require work in many packages will be
2996 signaled by a change to the minor number. The major patch
2997 level will be changed for any change to the meaning of the
2998 standards, however small; the minor patch level will be
2999 changed when only cosmetic, typographical or other edits
3000 are made which neither change the meaning of the document
3001 nor affect the contents of packages.
3005 Thus only the first three components of the policy version
3006 are significant in the
<em>Standards-Version
</em> control
3007 field, and so either these three components or all four
3008 components may be specified.
<footnote>
3009 In the past, people specified the full version number
3010 in the Standards-Version field, for example
"2.3.0.0".
3011 Since minor patch-level changes don't introduce new
3012 policy, it was thought it would be better to relax
3013 policy and only require the first
3 components to be
3014 specified, in this example
"2.3.0". All four
3015 components may still be used if someone wishes to do so.
3021 <sect1 id=
"f-Version">
3022 <heading><tt>Version
</tt></heading>
3025 The version number of a package. The format is:
3026 [
<var>epoch
</var><tt>:
</tt>]
<var>upstream_version
</var>[
<tt>-
</tt><var>debian_revision
</var>]
3030 The three components here are:
3032 <tag><var>epoch
</var></tag>
3035 This is a single (generally small) unsigned integer. It
3036 may be omitted, in which case zero is assumed. If it is
3037 omitted then the
<var>upstream_version
</var> may not
3042 It is provided to allow mistakes in the version numbers
3043 of older versions of a package, and also a package's
3044 previous version numbering schemes, to be left behind.
3048 <tag><var>upstream_version
</var></tag>
3051 This is the main part of the version number. It is
3052 usually the version number of the original (
"upstream")
3053 package from which the
<file>.deb
</file> file has been made,
3054 if this is applicable. Usually this will be in the same
3055 format as that specified by the upstream author(s);
3056 however, it may need to be reformatted to fit into the
3057 package management system's format and comparison
3062 The comparison behavior of the package management system
3063 with respect to the
<var>upstream_version
</var> is
3064 described below. The
<var>upstream_version
</var>
3065 portion of the version number is mandatory.
3069 The
<var>upstream_version
</var> may contain only
3070 alphanumerics
<footnote>
3071 Alphanumerics are
<tt>A-Za-z0-
9</tt> only.
3073 and the characters
<tt>.
</tt> <tt>+
</tt> <tt>-
</tt>
3074 <tt>:
</tt> <tt>~
</tt> (full stop, plus, hyphen, colon,
3075 tilde) and should start with a digit. If there is no
3076 <var>debian_revision
</var> then hyphens are not allowed;
3077 if there is no
<var>epoch
</var> then colons are not
3082 <tag><var>debian_revision
</var></tag>
3085 This part of the version number specifies the version of
3086 the Debian package based on the upstream version. It
3087 may contain only alphanumerics and the characters
3088 <tt>+
</tt> <tt>.
</tt> <tt>~
</tt> (plus, full stop,
3089 tilde) and is compared in the same way as the
3090 <var>upstream_version
</var> is.
3094 It is optional; if it isn't present then the
3095 <var>upstream_version
</var> may not contain a hyphen.
3096 This format represents the case where a piece of
3097 software was written specifically to be a Debian
3098 package, where the Debian package source must always
3099 be identical to the pristine source and therefore no
3100 revision indication is required.
3104 It is conventional to restart the
3105 <var>debian_revision
</var> at
<tt>1</tt> each time the
3106 <var>upstream_version
</var> is increased.
3110 The package management system will break the version
3111 number apart at the last hyphen in the string (if there
3112 is one) to determine the
<var>upstream_version
</var> and
3113 <var>debian_revision
</var>. The absence of a
3114 <var>debian_revision
</var> is equivalent to a
3115 <var>debian_revision
</var> of
<tt>0</tt>.
3122 When comparing two version numbers, first the
<var>epoch
</var>
3123 of each are compared, then the
<var>upstream_version
</var> if
3124 <var>epoch
</var> is equal, and then
<var>debian_revision
</var>
3125 if
<var>upstream_version
</var> is also equal.
3126 <var>epoch
</var> is compared numerically. The
3127 <var>upstream_version
</var> and
<var>debian_revision
</var>
3128 parts are compared by the package management system using the
3129 following algorithm:
3133 The strings are compared from left to right.
3137 First the initial part of each string consisting entirely of
3138 non-digit characters is determined. These two parts (one of
3139 which may be empty) are compared lexically. If a difference
3140 is found it is returned. The lexical comparison is a
3141 comparison of ASCII values modified so that all the letters
3142 sort earlier than all the non-letters and so that a tilde
3143 sorts before anything, even the end of a part. For example,
3144 the following parts are in sorted order from earliest to
3145 latest:
<tt>~~
</tt>,
<tt>~~a
</tt>,
<tt>~
</tt>, the empty part,
3146 <tt>a
</tt>.
<footnote>
3147 One common use of
<tt>~
</tt> is for upstream pre-releases.
3148 For example,
<tt>1.0~beta1~svn1245
</tt> sorts earlier than
3149 <tt>1.0~beta1
</tt>, which sorts earlier than
<tt>1.0</tt>.
3154 Then the initial part of the remainder of each string which
3155 consists entirely of digit characters is determined. The
3156 numerical values of these two parts are compared, and any
3157 difference found is returned as the result of the comparison.
3158 For these purposes an empty string (which can only occur at
3159 the end of one or both version strings being compared) counts
3164 These two steps (comparing and removing initial non-digit
3165 strings and initial digit strings) are repeated until a
3166 difference is found or both strings are exhausted.
3170 Note that the purpose of epochs is to allow us to leave behind
3171 mistakes in version numbering, and to cope with situations
3172 where the version numbering scheme changes. It is
3173 <em>not
</em> intended to cope with version numbers containing
3174 strings of letters which the package management system cannot
3175 interpret (such as
<tt>ALPHA
</tt> or
<tt>pre-
</tt>), or with
3176 silly orderings.
<footnote>
3177 The author of this manual has heard of a package whose
3178 versions went
<tt>1.1</tt>,
<tt>1.2</tt>,
<tt>1.3</tt>,
3179 <tt>1</tt>,
<tt>2.1</tt>,
<tt>2.2</tt>,
<tt>2</tt> and so
3185 <sect1 id=
"f-Description">
3186 <heading><tt>Description
</tt></heading>
3189 In a source or binary control file, the
<tt>Description
</tt>
3190 field contains a description of the binary package, consisting
3191 of two parts, the synopsis or the short description, and the
3192 long description. The field's format is as follows:
3197 Description:
<single line synopsis
>
3198 <extended description over several lines
>
3203 The lines in the extended description can have these formats:
3209 Those starting with a single space are part of a paragraph.
3210 Successive lines of this form will be word-wrapped when
3211 displayed. The leading space will usually be stripped off.
3215 Those starting with two or more spaces. These will be
3216 displayed verbatim. If the display cannot be panned
3217 horizontally, the displaying program will line wrap them
"hard"
3218 (i.e., without taking account of word breaks). If it can they
3219 will be allowed to trail off to the right. None, one or two
3220 initial spaces may be deleted, but the number of spaces
3221 deleted from each line will be the same (so that you can have
3222 indenting work correctly, for example).
3226 Those containing a single space followed by a single full stop
3227 character. These are rendered as blank lines. This is the
3228 <em>only
</em> way to get a blank line
<footnote>
3229 Completely empty lines will not be rendered as blank lines.
3230 Instead, they will cause the parser to think you're starting
3231 a whole new record in the control file, and will therefore
3232 likely abort with an error.
3237 Those containing a space, a full stop and some more characters.
3238 These are for future expansion. Do not use them.
3244 Do not use tab characters. Their effect is not predictable.
3248 See
<ref id=
"descriptions"> for further information on this.
3252 In a
<file>.changes
</file> file, the
<tt>Description
</tt>
3253 field contains a summary of the descriptions for the packages
3254 being uploaded. For this case, the first line of the field
3255 value (the part on the same line as
<tt>Description:
</tt>) is
3256 always empty. The content of the field is expressed as
3257 continuation lines, one line per package. Each line is
3258 indented by one space and contains the name of a binary
3259 package, a space, a hyphen (
<tt>-
</tt>), a space, and the
3260 short description line from that package.
3264 <sect1 id=
"f-Distribution">
3265 <heading><tt>Distribution
</tt></heading>
3268 In a
<file>.changes
</file> file or parsed changelog output
3269 this contains the (space-separated) name(s) of the
3270 distribution(s) where this version of the package should
3271 be installed. Valid distributions are determined by the
3272 archive maintainers.
<footnote>
3273 Example distribution names in the Debian archive used in
3274 <file>.changes
</file> files are:
3275 <taglist compact=
"compact">
3276 <tag><em>unstable
</em></tag>
3278 This distribution value refers to the
3279 <em>developmental
</em> part of the Debian distribution
3280 tree. Most new packages, new upstream versions of
3281 packages and bug fixes go into the
<em>unstable
</em>
3285 <tag><em>experimental
</em></tag>
3287 The packages with this distribution value are deemed
3288 by their maintainers to be high risk. Oftentimes they
3289 represent early beta or developmental packages from
3290 various sources that the maintainers want people to
3291 try, but are not ready to be a part of the other parts
3292 of the Debian distribution tree.
3297 Others are used for updating stable releases or for
3298 security uploads. More information is available in the
3299 Debian Developer's Reference, section
"The Debian
3303 The Debian archive software only supports listing a single
3304 distribution. Migration of packages to other distributions is
3305 handled outside of the upload process.
3310 <heading><tt>Date
</tt></heading>
3313 This field includes the date the package was built or last
3314 edited. It must be in the same format as the
<var>date
</var>
3315 in a
<file>debian/changelog
</file> entry.
3319 The value of this field is usually extracted from the
3320 <file>debian/changelog
</file> file - see
3321 <ref id=
"dpkgchangelog">).
3325 <sect1 id=
"f-Format">
3326 <heading><tt>Format
</tt></heading>
3329 In
<qref id=
"debianchangesfiles"><file>.changes
</file></qref>
3330 files, this field declares the format version of that file.
3331 The syntax of the field value is the same as that of
3332 a
<qref id=
"f-Version">package version number
</qref> except
3333 that no epoch or Debian revision is allowed. The format
3334 described in this document is
<tt>&changesversion;</tt>.
3338 In
<qref id=
"debiansourcecontrolfiles"><file>.dsc
</file>
3339 Debian source control
</qref> files, this field declares the
3340 format of the source package. The field value is used by
3341 programs acting on a source package to interpret the list of
3342 files in the source package and determine how to unpack it.
3343 The syntax of the field value is a numeric major revision, a
3344 period, a numeric minor revision, and then an optional subtype
3345 after whitespace, which if specified is an alphanumeric word
3346 in parentheses. The subtype is optional in the syntax but may
3347 be mandatory for particular source format revisions.
3349 The source formats currently supported by the Debian archive
3350 software are
<tt>1.0</tt>,
<tt>3.0 (native)
</tt>,
3351 and
<tt>3.0 (quilt)
</tt>.
3356 <sect1 id=
"f-Urgency">
3357 <heading><tt>Urgency
</tt></heading>
3360 This is a description of how important it is to upgrade to
3361 this version from previous ones. It consists of a single
3362 keyword taking one of the values
<tt>low
</tt>,
3363 <tt>medium
</tt>,
<tt>high
</tt>,
<tt>emergency
</tt>, or
3364 <tt>critical
</tt><footnote>
3365 Other urgency values are supported with configuration
3366 changes in the archive software but are not used in Debian.
3367 The urgency affects how quickly a package will be considered
3368 for inclusion into the
<tt>testing
</tt> distribution and
3369 gives an indication of the importance of any fixes included
3370 in the upload.
<tt>Emergency
</tt> and
<tt>critical
</tt> are
3371 treated as synonymous.
3372 </footnote> (not case-sensitive) followed by an optional
3373 commentary (separated by a space) which is usually in
3374 parentheses. For example:
3377 Urgency: low (HIGH for users of diversions)
3383 The value of this field is usually extracted from the
3384 <file>debian/changelog
</file> file - see
3385 <ref id=
"dpkgchangelog">.
3389 <sect1 id=
"f-Changes">
3390 <heading><tt>Changes
</tt></heading>
3393 This field contains the human-readable changes data, describing
3394 the differences between the last version and the current one.
3398 The first line of the field value (the part on the same line
3399 as
<tt>Changes:
</tt>) is always empty. The content of the
3400 field is expressed as continuation lines, with each line
3401 indented by at least one space. Blank lines must be
3402 represented by a line consisting only of a space and a full
3407 The value of this field is usually extracted from the
3408 <file>debian/changelog
</file> file - see
3409 <ref id=
"dpkgchangelog">).
3413 Each version's change information should be preceded by a
3414 "title" line giving at least the version, distribution(s)
3415 and urgency, in a human-readable way.
3419 If data from several versions is being returned the entry
3420 for the most recent version should be returned first, and
3421 entries should be separated by the representation of a
3422 blank line (the
"title" line may also be followed by the
3423 representation of a blank line).
3427 <sect1 id=
"f-Binary">
3428 <heading><tt>Binary
</tt></heading>
3431 This field is a list of binary packages. Its syntax and
3432 meaning varies depending on the control file in which it
3437 When it appears in the
<file>.dsc
</file> file, it lists binary
3438 packages which a source package can produce, separated by
3440 A space after each comma is conventional.
3441 </footnote>. It may span multiple lines. The source package
3442 does not necessarily produce all of these binary packages for
3443 every architecture. The source control file doesn't contain
3444 details of which architectures are appropriate for which of
3445 the binary packages.
3449 When it appears in a
<file>.changes
</file> file, it lists the
3450 names of the binary packages being uploaded, separated by
3451 whitespace (not commas). It may span multiple lines.
3455 <sect1 id=
"f-Installed-Size">
3456 <heading><tt>Installed-Size
</tt></heading>
3459 This field appears in the control files of binary packages,
3460 and in the
<file>Packages
</file> files. It gives an estimate
3461 of the total amount of disk space required to install the
3462 named package. Actual installed size may vary based on block
3463 size, file system properties, or actions taken by package
3468 The disk space is given as the integer value of the estimated
3469 installed size in bytes, divided by
1024 and rounded up.
3473 <sect1 id=
"f-Files">
3474 <heading><tt>Files
</tt></heading>
3477 This field contains a list of files with information about
3478 each one. The exact information and syntax varies with
3483 In all cases, Files is a multiline field. The first line of
3484 the field value (the part on the same line as
<tt>Files:
</tt>)
3485 is always empty. The content of the field is expressed as
3486 continuation lines, one line per file. Each line must be
3487 indented by one space and contain a number of sub-fields,
3488 separated by spaces, as described below.
3492 In the
<file>.dsc
</file> file, each line contains the MD5
3493 checksum, size and filename of the tar file and (if
3494 applicable) diff file which make up the remainder of the
3495 source package
<footnote>
3496 That is, the parts which are not the
<tt>.dsc
</tt>.
3497 </footnote>. For example:
3500 c6f698f19f2a2aa07dbb9bbda90a2754
571925 example_1.2.orig.tar.gz
3501 938512f08422f3509ff36f125f5873ba
6220 example_1.2-
1.diff.gz
3503 The exact forms of the filenames are described
3504 in
<ref id=
"pkg-sourcearchives">.
3508 In the
<file>.changes
</file> file this contains one line per
3509 file being uploaded. Each line contains the MD5 checksum,
3510 size, section and priority and the filename. For example:
3513 4c31ab7bfc40d3cf49d7811987390357
1428 text extra example_1.2-
1.dsc
3514 c6f698f19f2a2aa07dbb9bbda90a2754
571925 text extra example_1.2.orig.tar.gz
3515 938512f08422f3509ff36f125f5873ba
6220 text extra example_1.2-
1.diff.gz
3516 7c98fe853b3bbb47a00e5cd129b6cb56
703542 text extra example_1.2-
1_i386.deb
3518 The
<qref id=
"f-Section">section
</qref>
3519 and
<qref id=
"f-Priority">priority
</qref> are the values of
3520 the corresponding fields in the main source control file. If
3521 no section or priority is specified then
<tt>-
</tt> should be
3522 used, though section and priority values must be specified for
3523 new packages to be installed properly.
3527 The special value
<tt>byhand
</tt> for the section in a
3528 <tt>.changes
</tt> file indicates that the file in question
3529 is not an ordinary package file and must by installed by
3530 hand by the distribution maintainers. If the section is
3531 <tt>byhand
</tt> the priority should be
<tt>-
</tt>.
3535 If a new Debian revision of a package is being shipped and
3536 no new original source archive is being distributed the
3537 <tt>.dsc
</tt> must still contain the
<tt>Files
</tt> field
3538 entry for the original source archive
3539 <file><var>package
</var>_
<var>upstream-version
</var>.orig.tar.gz
</file>,
3540 but the
<file>.changes
</file> file should leave it out. In
3541 this case the original source archive on the distribution
3542 site must match exactly, byte-for-byte, the original
3543 source archive which was used to generate the
3544 <file>.dsc
</file> file and diff which are being uploaded.
</p>
3547 <sect1 id=
"f-Closes">
3548 <heading><tt>Closes
</tt></heading>
3551 A space-separated list of bug report numbers that the upload
3552 governed by the .changes file closes.
3556 <sect1 id=
"f-Homepage">
3557 <heading><tt>Homepage
</tt></heading>
3560 The URL of the web site for this package, preferably (when
3561 applicable) the site from which the original source can be
3562 obtained and any additional upstream documentation or
3563 information may be found. The content of this field is a
3564 simple URL without any surrounding characters such as
3569 <sect1 id=
"f-Checksums">
3570 <heading><tt>Checksums-Sha1
</tt>
3571 and
<tt>Checksums-Sha256
</tt></heading>
3574 These fields contain a list of files with a checksum and size
3575 for each one. Both
<tt>Checksums-Sha1
</tt>
3576 and
<tt>Checksums-Sha256
</tt> have the same syntax and differ
3577 only in the checksum algorithm used: SHA-
1
3578 for
<tt>Checksums-Sha1
</tt> and SHA-
256
3579 for
<tt>Checksums-Sha256
</tt>.
3583 <tt>Checksums-Sha1
</tt> and
<tt>Checksums-Sha256
</tt> are
3584 multiline fields. The first line of the field value (the part
3585 on the same line as
<tt>Checksums-Sha1:
</tt>
3586 or
<tt>Checksums-Sha256:
</tt>) is always empty. The content
3587 of the field is expressed as continuation lines, one line per
3588 file. Each line consists of the checksum, a space, the file
3589 size, a space, and the file name. For example (from
3590 a
<file>.changes
</file> file):
3593 1f418afaa01464e63cc1ee8a66a05f0848bd155c
1276 example_1.0-
1.dsc
3594 a0ed1456fad61116f868b1855530dbe948e20f06
171602 example_1.0.orig.tar.gz
3595 5e86ecf0671e113b63388dac81dd8d00e00ef298
6137 example_1.0-
1.debian.tar.gz
3596 71a0ff7da0faaf608481195f9cf30974b142c183
548402 example_1.0-
1_i386.deb
3598 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272
1276 example_1.0-
1.dsc
3599 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128
171602 example_1.0.orig.tar.gz
3600 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288
6137 example_1.0-
1.debian.tar.gz
3601 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664
548402 example_1.0-
1_i386.deb
3606 In the
<file>.dsc
</file> file, these fields should list all
3607 files that make up the source package. In
3608 the
<file>.changes
</file> file, these fields should list all
3609 files being uploaded. The list of files in these fields
3610 must match the list of files in the
<tt>Files
</tt> field.
3616 <heading>User-defined fields
</heading>
3619 Additional user-defined fields may be added to the
3620 source package control file. Such fields will be
3621 ignored, and not copied to (for example) binary or
3622 source package control files or upload control files.
3626 If you wish to add additional unsupported fields to
3627 these output files you should use the mechanism
3632 Fields in the main source control information file with
3633 names starting
<tt>X
</tt>, followed by one or more of
3634 the letters
<tt>BCS
</tt> and a hyphen
<tt>-
</tt>, will
3635 be copied to the output files. Only the part of the
3636 field name after the hyphen will be used in the output
3637 file. Where the letter
<tt>B
</tt> is used the field
3638 will appear in binary package control files, where the
3639 letter
<tt>S
</tt> is used in source package control
3640 files and where
<tt>C
</tt> is used in upload control
3641 (
<tt>.changes
</tt>) files.
3645 For example, if the main source information control file
3648 XBS-Comment: I stand between the candle and the star.
3650 then the binary and source package control files will contain the
3653 Comment: I stand between the candle and the star.
3662 <chapt id=
"maintainerscripts">
3663 <heading>Package maintainer scripts and installation procedure
</heading>
3666 <heading>Introduction to package maintainer scripts
</heading>
3669 It is possible to supply scripts as part of a package which
3670 the package management system will run for you when your
3671 package is installed, upgraded or removed.
3675 These scripts are the control information
3676 files
<prgn>preinst
</prgn>,
<prgn>postinst
</prgn>,
<prgn>prerm
</prgn>
3677 and
<prgn>postrm
</prgn>. They must be proper executable files;
3678 if they are scripts (which is recommended), they must start with
3679 the usual
<tt>#!
</tt> convention. They should be readable and
3680 executable by anyone, and must not be world-writable.
3684 The package management system looks at the exit status from
3685 these scripts. It is important that they exit with a
3686 non-zero status if there is an error, so that the package
3687 management system can stop its processing. For shell
3688 scripts this means that you
<em>almost always
</em> need to
3689 use
<tt>set -e
</tt> (this is usually true when writing shell
3690 scripts, in fact). It is also important, of course, that
3691 they exit with a zero status if everything went well.
3695 Additionally, packages interacting with users
3696 using
<prgn>debconf
</prgn> in the
<prgn>postinst
</prgn> script
3697 should install a
<prgn>config
</prgn> script as a control
3698 information file. See
<ref id=
"maintscriptprompt"> for details.
3702 When a package is upgraded a combination of the scripts from
3703 the old and new packages is called during the upgrade
3704 procedure. If your scripts are going to be at all
3705 complicated you need to be aware of this, and may need to
3706 check the arguments to your scripts.
3710 Broadly speaking the
<prgn>preinst
</prgn> is called before
3711 (a particular version of) a package is installed, and the
3712 <prgn>postinst
</prgn> afterwards; the
<prgn>prerm
</prgn>
3713 before (a version of) a package is removed and the
3714 <prgn>postrm
</prgn> afterwards.
3718 Programs called from maintainer scripts should not normally
3719 have a path prepended to them. Before installation is
3720 started, the package management system checks to see if the
3721 programs
<prgn>ldconfig
</prgn>,
3722 <prgn>start-stop-daemon
</prgn>,
<prgn>install-info
</prgn>,
3723 and
<prgn>update-rc.d
</prgn> can be found via the
3724 <tt>PATH
</tt> environment variable. Those programs, and any
3725 other program that one would expect to be in the
3726 <tt>PATH
</tt>, should thus be invoked without an absolute
3727 pathname. Maintainer scripts should also not reset the
3728 <tt>PATH
</tt>, though they might choose to modify it by
3729 prepending or appending package-specific directories. These
3730 considerations really apply to all shell scripts.
</p>
3733 <sect id=
"idempotency">
3734 <heading>Maintainer scripts idempotency
</heading>
3737 It is necessary for the error recovery procedures that the
3738 scripts be idempotent. This means that if it is run
3739 successfully, and then it is called again, it doesn't bomb
3740 out or cause any harm, but just ensures that everything is
3741 the way it ought to be. If the first call failed, or
3742 aborted half way through for some reason, the second call
3743 should merely do the things that were left undone the first
3744 time, if any, and exit with a success status if everything
3746 This is so that if an error occurs, the user interrupts
3747 <prgn>dpkg
</prgn> or some other unforeseen circumstance
3748 happens you don't leave the user with a badly-broken
3749 package when
<prgn>dpkg
</prgn> attempts to repeat the
3755 <sect id=
"controllingterminal">
3756 <heading>Controlling terminal for maintainer scripts
</heading>
3759 Maintainer scripts are not guaranteed to run with a controlling
3760 terminal and may not be able to interact with the user. They
3761 must be able to fall back to noninteractive behavior if no
3762 controlling terminal is available. Maintainer scripts that
3763 prompt via a program conforming to the Debian Configuration
3764 Management Specification (see
<ref id=
"maintscriptprompt">) may
3765 assume that program will handle falling back to noninteractive
3770 For high-priority prompts without a reasonable default answer,
3771 maintainer scripts may abort if there is no controlling
3772 terminal. However, this situation should be avoided if at all
3773 possible, since it prevents automated or unattended installs.
3774 In most cases, users will consider this to be a bug in the
3779 <sect id=
"exitstatus">
3780 <heading>Exit status
</heading>
3783 Each script must return a zero exit status for
3784 success, or a nonzero one for failure, since the package
3785 management system looks for the exit status of these scripts
3786 and determines what action to take next based on that datum.
3790 <sect id=
"mscriptsinstact"><heading>Summary of ways maintainer
3795 <list compact=
"compact">
3797 <var>new-preinst
</var> <tt>install
</tt>
3800 <var>new-preinst
</var> <tt>install
</tt> <var>old-version
</var>
3803 <var>new-preinst
</var> <tt>upgrade
</tt> <var>old-version
</var>
3806 <var>old-preinst
</var> <tt>abort-upgrade
</tt>
3807 <var>new-version
</var>
3812 <list compact=
"compact">
3814 <var>postinst
</var> <tt>configure
</tt>
3815 <var>most-recently-configured-version
</var>
3818 <var>old-postinst
</var> <tt>abort-upgrade
</tt>
3819 <var>new-version
</var>
3822 <var>conflictor's-postinst
</var> <tt>abort-remove
</tt>
3823 <tt>in-favour
</tt> <var>package
</var>
3824 <var>new-version
</var>
3827 <var>postinst
</var> <tt>abort-remove
</tt>
3830 <var>deconfigured's-postinst
</var>
3831 <tt>abort-deconfigure
</tt> <tt>in-favour
</tt>
3832 <var>failed-install-package
</var> <var>version
</var>
3833 [
<tt>removing
</tt> <var>conflicting-package
</var>
3839 <list compact=
"compact">
3841 <var>prerm
</var> <tt>remove
</tt>
3844 <var>old-prerm
</var> <tt>upgrade
</tt>
3845 <var>new-version
</var>
3848 <var>new-prerm
</var> <tt>failed-upgrade
</tt>
3849 <var>old-version
</var>
3852 <var>conflictor's-prerm
</var> <tt>remove
</tt>
3853 <tt>in-favour
</tt> <var>package
</var>
3854 <var>new-version
</var>
3857 <var>deconfigured's-prerm
</var> <tt>deconfigure
</tt>
3858 <tt>in-favour
</tt> <var>package-being-installed
</var>
3859 <var>version
</var> [
<tt>removing
</tt>
3860 <var>conflicting-package
</var>
3866 <list compact=
"compact">
3868 <var>postrm
</var> <tt>remove
</tt>
3871 <var>postrm
</var> <tt>purge
</tt>
3874 <var>old-postrm
</var> <tt>upgrade
</tt>
3875 <var>new-version
</var>
3878 <var>new-postrm
</var> <tt>failed-upgrade
</tt>
3879 <var>old-version
</var>
3882 <var>new-postrm
</var> <tt>abort-install
</tt>
3885 <var>new-postrm
</var> <tt>abort-install
</tt>
3886 <var>old-version
</var>
3889 <var>new-postrm
</var> <tt>abort-upgrade
</tt>
3890 <var>old-version
</var>
3893 <var>disappearer's-postrm
</var> <tt>disappear
</tt>
3894 <var>overwriter
</var>
3895 <var>overwriter-version
</var>
3901 <sect id=
"unpackphase">
3902 <heading>Details of unpack phase of installation or upgrade
</heading>
3905 The procedure on installation/upgrade/overwrite/disappear
3906 (i.e., when running
<tt>dpkg --unpack
</tt>, or the unpack
3907 stage of
<tt>dpkg --install
</tt>) is as follows. In each
3908 case, if a major error occurs (unless listed below) the
3909 actions are, in general, run backwards - this means that the
3910 maintainer scripts are run with different arguments in
3911 reverse order. These are the
"error unwind" calls listed
3918 If a version of the package is already installed, call
3919 <example compact=
"compact">
3920 <var>old-prerm
</var> upgrade
<var>new-version
</var>
3924 If the script runs but exits with a non-zero
3925 exit status,
<prgn>dpkg
</prgn> will attempt:
3926 <example compact=
"compact">
3927 <var>new-prerm
</var> failed-upgrade
<var>old-version
</var>
3929 If this works, the upgrade continues. If this
3930 does not work, the error unwind:
3931 <example compact=
"compact">
3932 <var>old-postinst
</var> abort-upgrade
<var>new-version
</var>
3934 If this works, then the old-version is
3935 "Installed", if not, the old version is in a
3936 "Half-Configured" state.
3942 If a
"conflicting" package is being removed at the same time,
3943 or if any package will be broken (due to
<tt>Breaks
</tt>):
3946 If
<tt>--auto-deconfigure
</tt> is
3947 specified, call, for each package to be deconfigured
3948 due to
<tt>Breaks
</tt>:
3949 <example compact=
"compact">
3950 <var>deconfigured's-prerm
</var> deconfigure \
3951 in-favour
<var>package-being-installed
</var> <var>version
</var>
3954 <example compact=
"compact">
3955 <var>deconfigured's-postinst
</var> abort-deconfigure \
3956 in-favour
<var>package-being-installed-but-failed
</var> <var>version
</var>
3958 The deconfigured packages are marked as
3959 requiring configuration, so that if
3960 <tt>--install
</tt> is used they will be
3961 configured again if possible.
3964 If any packages depended on a conflicting
3965 package being removed and
<tt>--auto-deconfigure
</tt> is
3966 specified, call, for each such package:
3967 <example compact=
"compact">
3968 <var>deconfigured's-prerm
</var> deconfigure \
3969 in-favour
<var>package-being-installed
</var> <var>version
</var> \
3970 removing
<var>conflicting-package
</var> <var>version
</var>
3973 <example compact=
"compact">
3974 <var>deconfigured's-postinst
</var> abort-deconfigure \
3975 in-favour
<var>package-being-installed-but-failed
</var> <var>version
</var> \
3976 removing
<var>conflicting-package
</var> <var>version
</var>
3978 The deconfigured packages are marked as
3979 requiring configuration, so that if
3980 <tt>--install
</tt> is used they will be
3981 configured again if possible.
3984 To prepare for removal of each conflicting package, call:
3985 <example compact=
"compact">
3986 <var>conflictor's-prerm
</var> remove \
3987 in-favour
<var>package
</var> <var>new-version
</var>
3990 <example compact=
"compact">
3991 <var>conflictor's-postinst
</var> abort-remove \
3992 in-favour
<var>package
</var> <var>new-version
</var>
4001 If the package is being upgraded, call:
4002 <example compact=
"compact">
4003 <var>new-preinst
</var> upgrade
<var>old-version
</var>
4005 If this fails, we call:
4007 <var>new-postrm
</var> abort-upgrade
<var>old-version
</var>
4014 <var>old-postinst
</var> abort-upgrade
<var>new-version
</var>
4016 is called. If this works, then the old version
4017 is in an
"Installed" state, or else it is left
4018 in an
"Unpacked" state.
4023 If it fails, then the old version is left
4024 in an
"Half-Installed" state.
4031 Otherwise, if the package had some configuration
4032 files from a previous version installed (i.e., it
4033 is in the
"configuration files only" state):
4034 <example compact=
"compact">
4035 <var>new-preinst
</var> install
<var>old-version
</var>
4039 <var>new-postrm
</var> abort-install
<var>old-version
</var>
4041 If this fails, the package is left in a
4042 "Half-Installed" state, which requires a
4043 reinstall. If it works, the packages is left in
4044 a
"Config-Files" state.
4047 Otherwise (i.e., the package was completely purged):
4048 <example compact=
"compact">
4049 <var>new-preinst
</var> install
4052 <example compact=
"compact">
4053 <var>new-postrm
</var> abort-install
4055 If the error-unwind fails, the package is in a
4056 "Half-Installed" phase, and requires a
4057 reinstall. If the error unwind works, the
4058 package is in a not installed state.
4065 The new package's files are unpacked, overwriting any
4066 that may be on the system already, for example any
4067 from the old version of the same package or from
4068 another package. Backups of the old files are kept
4069 temporarily, and if anything goes wrong the package
4070 management system will attempt to put them back as
4071 part of the error unwind.
4075 It is an error for a package to contain files which
4076 are on the system in another package, unless
4077 <tt>Replaces
</tt> is used (see
<ref id=
"replaces">).
4079 The following paragraph is not currently the case:
4080 Currently the <tt>- - force-overwrite</tt> flag is
4081 enabled, downgrading it to a warning, but this may not
4087 It is a more serious error for a package to contain a
4088 plain file or other kind of non-directory where another
4089 package has a directory (again, unless
4090 <tt>Replaces
</tt> is used). This error can be
4091 overridden if desired using
4092 <tt>--force-overwrite-dir
</tt>, but this is not
4097 Packages which overwrite each other's files produce
4098 behavior which, though deterministic, is hard for the
4099 system administrator to understand. It can easily
4100 lead to
"missing" programs if, for example, a package
4101 is installed which overwrites a file from another
4102 package, and is then removed again.
<footnote>
4103 Part of the problem is due to what is arguably a
4104 bug in
<prgn>dpkg
</prgn>.
4109 A directory will never be replaced by a symbolic link
4110 to a directory or vice versa; instead, the existing
4111 state (symlink or not) will be left alone and
4112 <prgn>dpkg
</prgn> will follow the symlink if there is
4121 If the package is being upgraded, call
4122 <example compact=
"compact">
4123 <var>old-postrm
</var> upgrade
<var>new-version
</var>
4127 If this fails,
<prgn>dpkg
</prgn> will attempt:
4128 <example compact=
"compact">
4129 <var>new-postrm
</var> failed-upgrade
<var>old-version
</var>
4131 If this works, installation continues. If not,
4133 <example compact=
"compact">
4134 <var>old-preinst
</var> abort-upgrade
<var>new-version
</var>
4136 If this fails, the old version is left in a
4137 "Half-Installed" state. If it works, dpkg now
4139 <example compact=
"compact">
4140 <var>new-postrm
</var> abort-upgrade
<var>old-version
</var>
4142 If this fails, the old version is left in a
4143 "Half-Installed" state. If it works, dpkg now
4145 <example compact=
"compact">
4146 <var>old-postinst
</var> abort-upgrade
<var>new-version
</var>
4148 If this fails, the old version is in an
4155 This is the point of no return - if
4156 <prgn>dpkg
</prgn> gets this far, it won't back off
4157 past this point if an error occurs. This will
4158 leave the package in a fairly bad state, which
4159 will require a successful re-installation to clear
4160 up, but it's when
<prgn>dpkg
</prgn> starts doing
4161 things that are irreversible.
4166 Any files which were in the old version of the package
4167 but not in the new are removed.
4171 The new file list replaces the old.
4175 The new maintainer scripts replace the old.
4179 Any packages all of whose files have been overwritten
4180 during the installation, and which aren't required for
4181 dependencies, are considered to have been removed.
4182 For each such package
4185 <prgn>dpkg
</prgn> calls:
4186 <example compact=
"compact">
4187 <var>disappearer's-postrm
</var> disappear \
4188 <var>overwriter
</var> <var>overwriter-version
</var>
4192 The package's maintainer scripts are removed.
4195 It is noted in the status database as being in a
4196 sane state, namely not installed (any conffiles
4197 it may have are ignored, rather than being
4198 removed by
<prgn>dpkg
</prgn>). Note that
4199 disappearing packages do not have their prerm
4200 called, because
<prgn>dpkg
</prgn> doesn't know
4201 in advance that the package is going to
4208 Any files in the package we're unpacking that are also
4209 listed in the file lists of other packages are removed
4210 from those lists. (This will lobotomize the file list
4211 of the
"conflicting" package if there is one.)
4215 The backup files made during installation, above, are
4221 The new package's status is now sane, and recorded as
4226 Here is another point of no return - if the
4227 conflicting package's removal fails we do not unwind
4228 the rest of the installation; the conflicting package
4229 is left in a half-removed limbo.
4234 If there was a conflicting package we go and do the
4235 removal actions (described below), starting with the
4236 removal of the conflicting package's files (any that
4237 are also in the package being installed have already
4238 been removed from the conflicting package's file list,
4239 and so do not get removed now).
4245 <sect id=
"configdetails"><heading>Details of configuration
</heading>
4248 When we configure a package (this happens with
<tt>dpkg
4249 --install
</tt> and
<tt>dpkg --configure
</tt>), we first
4250 update any
<tt>conffile
</tt>s and then call:
4251 <example compact=
"compact">
4252 <var>postinst
</var> configure
<var>most-recently-configured-version
</var>
4257 No attempt is made to unwind after errors during
4258 configuration. If the configuration fails, the package is in
4259 a
"Failed Config" state, and an error message is generated.
4263 If there is no most recently configured version
4264 <prgn>dpkg
</prgn> will pass a null argument.
4267 Historical note: Truly ancient (pre-
1997) versions of
4268 <prgn>dpkg
</prgn> passed
<tt><unknown
></tt>
4269 (including the angle brackets) in this case. Even older
4270 ones did not pass a second argument at all, under any
4271 circumstance. Note that upgrades using such an old dpkg
4272 version are unlikely to work for other reasons, even if
4273 this old argument behavior is handled by your postinst script.
4279 <sect id=
"removedetails"><heading>Details of removal and/or
4280 configuration purging
</heading>
4286 <example compact=
"compact">
4287 <var>prerm
</var> remove
4291 If prerm fails during replacement due to conflict
4293 <var>conflictor's-postinst
</var> abort-remove \
4294 in-favour
<var>package
</var> <var>new-version
</var>
4298 <var>postinst
</var> abort-remove
4302 If this fails, the package is in a
"Half-Configured"
4303 state, or else it remains
"Installed".
4307 The package's files are removed (except
<tt>conffile
</tt>s).
4310 <example compact=
"compact">
4311 <var>postrm
</var> remove
4315 If it fails, there's no error unwind, and the package is in
4316 an
"Half-Installed" state.
4321 All the maintainer scripts except the
<prgn>postrm
</prgn>
4326 If we aren't purging the package we stop here. Note
4327 that packages which have no
<prgn>postrm
</prgn> and no
4328 <tt>conffile
</tt>s are automatically purged when
4329 removed, as there is no difference except for the
4330 <prgn>dpkg
</prgn> status.
4334 The
<tt>conffile
</tt>s and any backup files
4335 (
<tt>~
</tt>-files,
<tt>#*#
</tt> files,
4336 <tt>%
</tt>-files,
<tt>.dpkg-{old,new,tmp}
</tt>, etc.)
4341 <example compact=
"compact">
4342 <var>postrm
</var> purge
4346 If this fails, the package remains in a
"Config-Files"
4351 The package's file list is removed.
4360 <chapt id=
"relationships">
4361 <heading>Declaring relationships between packages
</heading>
4363 <sect id=
"depsyntax">
4364 <heading>Syntax of relationship fields
</heading>
4367 These fields all have a uniform syntax. They are a list of
4368 package names separated by commas.
4372 In the
<tt>Depends
</tt>,
<tt>Recommends
</tt>,
4373 <tt>Suggests
</tt>,
<tt>Pre-Depends
</tt>,
4374 <tt>Build-Depends
</tt> and
<tt>Build-Depends-Indep
</tt>
4375 control fields of the package, which declare
4376 dependencies on other packages, the package names listed may
4377 also include lists of alternative package names, separated
4378 by vertical bar (pipe) symbols
<tt>|
</tt>. In such a case,
4379 if any one of the alternative packages is installed, that
4380 part of the dependency is considered to be satisfied.
4384 All of the fields except for
<tt>Provides
</tt> may restrict
4385 their applicability to particular versions of each named
4386 package. This is done in parentheses after each individual
4387 package name; the parentheses should contain a relation from
4388 the list below followed by a version number, in the format
4389 described in
<ref id=
"f-Version">.
4393 The relations allowed are
<tt><<</tt>,
<tt><=
</tt>,
4394 <tt>=
</tt>,
<tt>>=
</tt> and
<tt>>></tt> for
4395 strictly earlier, earlier or equal, exactly equal, later or
4396 equal and strictly later, respectively. The deprecated
4397 forms
<tt><</tt> and
<tt>></tt> were used to mean
4398 earlier/later or equal, rather than strictly earlier/later,
4399 so they should not appear in new packages (though
4400 <prgn>dpkg
</prgn> still supports them).
4404 Whitespace may appear at any point in the version
4405 specification subject to the rules in
<ref
4406 id=
"controlsyntax">, and must appear where it's necessary to
4407 disambiguate; it is not otherwise significant. All of the
4408 relationship fields may span multiple lines. For
4409 consistency and in case of future changes to
4410 <prgn>dpkg
</prgn> it is recommended that a single space be
4411 used after a version relationship and before a version
4412 number; it is also conventional to put a single space after
4413 each comma, on either side of each vertical bar, and before
4414 each open parenthesis. When wrapping a relationship field, it
4415 is conventional to do so after a comma and before the space
4416 following that comma.
4420 For example, a list of dependencies might appear as:
4421 <example compact=
"compact">
4424 Depends: libc6 (
>=
2.2.1), exim | mail-transport-agent
4429 Relationships may be restricted to a certain set of
4430 architectures. This is indicated in brackets after each
4431 individual package name and the optional version specification.
4432 The brackets enclose a list of Debian architecture names
4433 separated by whitespace. Exclamation marks may be prepended to
4434 each of the names. (It is not permitted for some names to be
4435 prepended with exclamation marks while others aren't.)
4439 For build relationship fields
4440 (
<tt>Build-Depends
</tt>,
<tt>Build-Depends-Indep
</tt>,
4441 <tt>Build-Conflicts
</tt> and
<tt>Build-Conflicts-Indep
</tt>), if
4442 the current Debian host architecture is not in this list and
4443 there are no exclamation marks in the list, or it is in the list
4444 with a prepended exclamation mark, the package name and the
4445 associated version specification are ignored completely for the
4446 purposes of defining the relationships.
4451 <example compact=
"compact">
4453 Build-Depends-Indep: texinfo
4454 Build-Depends: kernel-headers-
2.2.10 [!hurd-i386],
4455 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4457 requires
<tt>kernel-headers-
2.2.10</tt> on all architectures
4458 other than hurd-i386 and requires
<tt>hurd-dev
</tt> and
4459 <tt>gnumach-dev
</tt> only on hurd-i386.
4463 For binary relationship fields, the architecture restriction
4464 syntax is only supported in the source package control
4465 file
<file>debian/control
</file>. When the corresponding binary
4466 package control file is generated, the relationship will either
4467 be omitted or included without the architecture restriction
4468 based on the architecture of the binary package. This means
4469 that architecture restrictions must not be used in binary
4470 relationship fields for architecture-independent packages
4471 (
<tt>Architecture: all
</tt>).
4476 <example compact=
"compact">
4477 Depends: foo [i386], bar [amd64]
4479 becomes
<tt>Depends: foo
</tt> when the package is built on
4480 the
<tt>i386
</tt> architecture,
<tt>Depends: bar
</tt> when the
4481 package is built on the
<tt>amd64
</tt> architecture, and omitted
4482 entirely in binary packages built on all other architectures.
4486 If the architecture-restricted dependency is part of a set of
4487 alternatives using
<tt>|
</tt>, that alternative is ignored
4488 completely on architectures that do not match the restriction.
4490 <example compact=
"compact">
4491 Build-Depends: foo [!i386] | bar [!amd64]
4493 is equivalent to
<tt>bar
</tt> on the i386 architecture, to
4494 <tt>foo
</tt> on the amd64 architecture, and to
<tt>foo |
4495 bar
</tt> on all other architectures.
4499 Relationships may also be restricted to a certain set of
4500 architectures using architecture wildcards. The syntax for
4501 declaring such restrictions is the same as declaring
4502 restrictions using a certain set of architectures without
4503 architecture wildcards. For example:
4504 <example compact=
"compact">
4505 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4507 is equivalent to
<tt>foo
</tt> on architectures using the Linux
4508 kernel and any cpu,
<tt>bar
</tt> on architectures using any
4509 kernel and an i386 cpu, and
<tt>baz
</tt> on any architecture
4510 using a kernel other than Linux.
4514 Note that the binary package relationship fields such as
4515 <tt>Depends
</tt> appear in one of the binary package
4516 sections of the control file, whereas the build-time
4517 relationships such as
<tt>Build-Depends
</tt> appear in the
4518 source package section of the control file (which is the
4523 <sect id=
"binarydeps">
4524 <heading>Binary Dependencies -
<tt>Depends
</tt>,
4525 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
<tt>Enhances
</tt>,
4526 <tt>Pre-Depends
</tt>
4530 Packages can declare in their control file that they have
4531 certain relationships to other packages - for example, that
4532 they may not be installed at the same time as certain other
4533 packages, and/or that they depend on the presence of others.
4537 This is done using the
<tt>Depends
</tt>,
<tt>Pre-Depends
</tt>,
4538 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
<tt>Enhances
</tt>,
4539 <tt>Breaks
</tt> and
<tt>Conflicts
</tt> control fields.
4540 <tt>Breaks
</tt> is described in
<ref id=
"breaks">, and
4541 <tt>Conflicts
</tt> is described in
<ref id=
"conflicts">. The
4542 rest are described below.
4546 These seven fields are used to declare a dependency
4547 relationship by one package on another. Except for
4548 <tt>Enhances
</tt> and
<tt>Breaks
</tt>, they appear in the
4549 depending (binary) package's control file.
4550 (
<tt>Enhances
</tt> appears in the recommending package's
4551 control file, and
<tt>Breaks
</tt> appears in the version of
4552 depended-on package which causes the named package to
4557 A
<tt>Depends
</tt> field takes effect
<em>only
</em> when a
4558 package is to be configured. It does not prevent a package
4559 being on the system in an unconfigured state while its
4560 dependencies are unsatisfied, and it is possible to replace
4561 a package whose dependencies are satisfied and which is
4562 properly installed with a different version whose
4563 dependencies are not and cannot be satisfied; when this is
4564 done the depending package will be left unconfigured (since
4565 attempts to configure it will give errors) and will not
4566 function properly. If it is necessary, a
4567 <tt>Pre-Depends
</tt> field can be used, which has a partial
4568 effect even when a package is being unpacked, as explained
4569 in detail below. (The other three dependency fields,
4570 <tt>Recommends
</tt>,
<tt>Suggests
</tt> and
4571 <tt>Enhances
</tt>, are only used by the various front-ends
4572 to
<prgn>dpkg
</prgn> such as
<prgn>apt-get
</prgn>,
4573 <prgn>aptitude
</prgn>, and
<prgn>dselect
</prgn>.)
4577 For this reason packages in an installation run are usually
4578 all unpacked first and all configured later; this gives
4579 later versions of packages with dependencies on later
4580 versions of other packages the opportunity to have their
4581 dependencies satisfied.
4585 In case of circular dependencies, since installation or
4586 removal order honoring the dependency order can't be
4587 established, dependency loops are broken at some point
4588 (based on rules below), and some packages may not be able to
4589 rely on their dependencies being present when being
4590 installed or removed, depending on which side of the break
4591 of the circular dependency loop they happen to be on. If one
4592 of the packages in the loop has no postinst script, then the
4593 cycle will be broken at that package, so as to ensure that
4594 all postinst scripts run with the dependencies properly
4595 configured if this is possible. Otherwise the breaking point
4600 The
<tt>Depends
</tt> field thus allows package maintainers
4601 to impose an order in which packages should be configured.
4605 The meaning of the five dependency fields is as follows:
4607 <tag><tt>Depends
</tt></tag>
4610 This declares an absolute dependency. A package will
4611 not be configured unless all of the packages listed in
4612 its
<tt>Depends
</tt> field have been correctly
4617 The
<tt>Depends
</tt> field should be used if the
4618 depended-on package is required for the depending
4619 package to provide a significant amount of
4624 The
<tt>Depends
</tt> field should also be used if the
4625 <prgn>postinst
</prgn>,
<prgn>prerm
</prgn> or
4626 <prgn>postrm
</prgn> scripts require the package to be
4627 present in order to run. Note, however, that the
4628 <prgn>postrm
</prgn> cannot rely on any non-essential
4629 packages to be present during the
<tt>purge
</tt>
4633 <tag><tt>Recommends
</tt></tag>
4636 This declares a strong, but not absolute, dependency.
4640 The
<tt>Recommends
</tt> field should list packages
4641 that would be found together with this one in all but
4642 unusual installations.
4646 <tag><tt>Suggests
</tt></tag>
4648 This is used to declare that one package may be more
4649 useful with one or more others. Using this field
4650 tells the packaging system and the user that the
4651 listed packages are related to this one and can
4652 perhaps enhance its usefulness, but that installing
4653 this one without them is perfectly reasonable.
4656 <tag><tt>Enhances
</tt></tag>
4658 This field is similar to Suggests but works in the
4659 opposite direction. It is used to declare that a
4660 package can enhance the functionality of another
4664 <tag><tt>Pre-Depends
</tt></tag>
4667 This field is like
<tt>Depends
</tt>, except that it
4668 also forces
<prgn>dpkg
</prgn> to complete installation
4669 of the packages named before even starting the
4670 installation of the package which declares the
4671 pre-dependency, as follows:
4675 When a package declaring a pre-dependency is about to
4676 be
<em>unpacked
</em> the pre-dependency can be
4677 satisfied if the depended-on package is either fully
4678 configured,
<em>or even if
</em> the depended-on
4679 package(s) are only unpacked or in the
"Half-Configured"
4680 state, provided that they have been configured
4681 correctly at some point in the past (and not removed
4682 or partially removed since). In this case, both the
4683 previously-configured and currently unpacked or
4684 "Half-Configured" versions must satisfy any version
4685 clause in the
<tt>Pre-Depends
</tt> field.
4689 When the package declaring a pre-dependency is about
4690 to be
<em>configured
</em>, the pre-dependency will be
4691 treated as a normal
<tt>Depends
</tt>, that is, it will
4692 be considered satisfied only if the depended-on
4693 package has been correctly configured.
4697 <tt>Pre-Depends
</tt> should be used sparingly,
4698 preferably only by packages whose premature upgrade or
4699 installation would hamper the ability of the system to
4700 continue with any upgrade that might be in progress.
4704 <tt>Pre-Depends
</tt> are also required if the
4705 <prgn>preinst
</prgn> script depends on the named
4706 package. It is best to avoid this situation if
4714 When selecting which level of dependency to use you should
4715 consider how important the depended-on package is to the
4716 functionality of the one declaring the dependency. Some
4717 packages are composed of components of varying degrees of
4718 importance. Such a package should list using
4719 <tt>Depends
</tt> the package(s) which are required by the
4720 more important components. The other components'
4721 requirements may be mentioned as Suggestions or
4722 Recommendations, as appropriate to the components' relative
4728 <heading>Packages which break other packages -
<tt>Breaks
</tt></heading>
4731 When one binary package declares that it breaks another,
4732 <prgn>dpkg
</prgn> will refuse to allow the package which
4733 declares
<tt>Breaks
</tt> be installed unless the broken
4734 package is deconfigured first, and it will refuse to
4735 allow the broken package to be reconfigured.
4739 A package will not be regarded as causing breakage merely
4740 because its configuration files are still installed; it must
4741 be at least
"Half-Installed".
4745 A special exception is made for packages which declare that
4746 they break their own package name or a virtual package which
4747 they provide (see below): this does not count as a real
4752 Normally a
<tt>Breaks
</tt> entry will have an
"earlier than"
4753 version clause; such a
<tt>Breaks
</tt> is introduced in the
4754 version of an (implicit or explicit) dependency which violates
4755 an assumption or reveals a bug in earlier versions of the broken
4756 package, or which takes over a file from earlier versions of the
4757 package named in
<tt>Breaks
</tt>. This use of
<tt>Breaks
</tt>
4758 will inform higher-level package management tools that the
4759 broken package must be upgraded before the new one.
4763 If the breaking package also overwrites some files from the
4764 older package, it should use
<tt>Replaces
</tt> to ensure this
4765 goes smoothly. See
<ref id=
"replaces"> for a full discussion
4766 of taking over files from other packages, including how to
4767 use
<tt>Breaks
</tt> in those cases.
4771 Many of the cases where
<tt>Breaks
</tt> should be used were
4772 previously handled with
<tt>Conflicts
</tt>
4773 because
<tt>Breaks
</tt> did not yet exist.
4774 Many
<tt>Conflicts
</tt> fields should now be
<tt>Breaks
</tt>.
4775 See
<ref id=
"conflicts"> for more information about the
4780 <sect id=
"conflicts">
4781 <heading>Conflicting binary packages -
<tt>Conflicts
</tt></heading>
4784 When one binary package declares a conflict with another
4785 using a
<tt>Conflicts
</tt> field,
<prgn>dpkg
</prgn> will
4786 refuse to allow them to be installed on the system at the
4787 same time. This is a stronger restriction than
<tt>Breaks
</tt>,
4788 which just prevents both packages from being configured at the
4789 same time. Conflicting packages cannot be unpacked on the
4790 system at the same time.
4794 If one package is to be installed, the other must be removed
4795 first. If the package being installed is marked as replacing
4796 (see
<ref id=
"replaces">, but note that
<tt>Breaks
</tt> should
4797 normally be used in this case) the one on the system, or the one
4798 on the system is marked as deselected, or both packages are
4799 marked
<tt>Essential
</tt>, then
<prgn>dpkg
</prgn> will
4800 automatically remove the package which is causing the conflict.
4801 Otherwise, it will halt the installation of the new package with
4802 an error. This mechanism is specifically designed to produce an
4803 error when the installed package is
<tt>Essential
</tt>, but the
4808 A package will not cause a conflict merely because its
4809 configuration files are still installed; it must be at least
4814 A special exception is made for packages which declare a
4815 conflict with their own package name, or with a virtual
4816 package which they provide (see below): this does not
4817 prevent their installation, and allows a package to conflict
4818 with others providing a replacement for it. You use this
4819 feature when you want the package in question to be the only
4820 package providing some feature.
4824 Normally,
<tt>Breaks
</tt> should be used instead
4825 of
<tt>Conflicts
</tt> since
<tt>Conflicts
</tt> imposes a
4826 stronger restriction on the ordering of package installation or
4827 upgrade and can make it more difficult for the package manager
4828 to find a correct solution to an upgrade or installation
4829 problem.
<tt>Breaks
</tt> should be used
4831 <item>when moving a file from one package to another (see
4832 <ref id=
"replaces">),
</item>
4833 <item>when splitting a package (a special case of the previous
4835 <item>when the breaking package exposes a bug in or interacts
4836 badly with particular versions of the broken
4839 <tt>Conflicts
</tt> should be used
4841 <item>when two packages provide the same file and will
4842 continue to do so,
</item>
4843 <item>in conjunction with
<tt>Provides
</tt> when only one
4844 package providing a given virtual facility may be installed
4845 at a time (see
<ref id=
"virtual">),
</item>
4846 <item>in other cases where one must prevent simultaneous
4847 installation of two packages for reasons that are ongoing
4848 (not fixed in a later version of one of the packages) or
4849 that must prevent both packages from being unpacked at the
4850 same time, not just configured.
</item>
4852 Be aware that adding
<tt>Conflicts
</tt> is normally not the best
4853 solution when two packages provide the same files. Depending on
4854 the reason for that conflict, using alternatives or renaming the
4855 files is often a better approach. See, for
4856 example,
<ref id=
"binaries">.
4860 Neither
<tt>Breaks
</tt> nor
<tt>Conflicts
</tt> should be used
4861 unless two packages cannot be installed at the same time or
4862 installing them both causes one of them to be broken or
4863 unusable. Having similar functionality or performing the same
4864 tasks as another package is not sufficient reason to
4865 declare
<tt>Breaks
</tt> or
<tt>Conflicts
</tt> with that package.
4869 A
<tt>Conflicts
</tt> entry may have an
"earlier than" version
4870 clause if the reason for the conflict is corrected in a later
4871 version of one of the packages. However, normally the presence
4872 of an
"earlier than" version clause is a sign
4873 that
<tt>Breaks
</tt> should have been used instead. An
"earlier
4874 than" version clause in
<tt>Conflicts
</tt>
4875 prevents
<prgn>dpkg
</prgn> from upgrading or installing the
4876 package which declares such a conflict until the upgrade or
4877 removal of the conflicted-with package has been completed, which
4878 is a strong restriction.
4882 <sect id=
"virtual"><heading>Virtual packages -
<tt>Provides
</tt>
4886 As well as the names of actual (
"concrete") packages, the
4887 package relationship fields
<tt>Depends
</tt>,
4888 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
<tt>Enhances
</tt>,
4889 <tt>Pre-Depends
</tt>,
<tt>Breaks
</tt>,
<tt>Conflicts
</tt>,
4890 <tt>Build-Depends
</tt>,
<tt>Build-Depends-Indep
</tt>,
4891 <tt>Build-Conflicts
</tt> and
<tt>Build-Conflicts-Indep
</tt>
4892 may mention
"virtual packages".
4896 A
<em>virtual package
</em> is one which appears in the
4897 <tt>Provides
</tt> control field of another package. The effect
4898 is as if the package(s) which provide a particular virtual
4899 package name had been listed by name everywhere the virtual
4900 package name appears. (See also
<ref id=
"virtual_pkg">)
4904 If there are both concrete and virtual packages of the same
4905 name, then the dependency may be satisfied (or the conflict
4906 caused) by either the concrete package with the name in
4907 question or any other concrete package which provides the
4908 virtual package with the name in question. This is so that,
4909 for example, supposing we have
4910 <example compact=
"compact">
4913 </example> and someone else releases an enhanced version of
4914 the
<tt>bar
</tt> package they can say:
4915 <example compact=
"compact">
4919 and the
<tt>bar-plus
</tt> package will now also satisfy the
4920 dependency for the
<tt>foo
</tt> package.
4924 If a relationship field has a version number attached, only real
4925 packages will be considered to see whether the relationship is
4926 satisfied (or the prohibition violated, for a conflict or
4927 breakage). In other words, if a version number is specified,
4928 this is a request to ignore all
<tt>Provides
</tt> for that
4929 package name and consider only real packages. The package
4930 manager will assume that a package providing that virtual
4931 package is not of the
"right" version. A
<tt>Provides
</tt>
4932 field may not contain version numbers, and the version number of
4933 the concrete package which provides a particular virtual package
4934 will not be considered when considering a dependency on or
4935 conflict with the virtual package name.
<footnote>
4936 It is possible that a future release of
<prgn>dpkg
</prgn> may
4937 add the ability to specify a version number for each virtual
4938 package it provides. This feature is not yet present,
4939 however, and is expected to be used only infrequently.
4944 To specify which of a set of real packages should be the default
4945 to satisfy a particular dependency on a virtual package, list
4946 the real package as an alternative before the virtual one.
4950 If the virtual package represents a facility that can only be
4951 provided by one real package at a time, such as
4952 the
<package>mail-transport-agent
</package> virtual package that
4953 requires installation of a binary that would conflict with all
4954 other providers of that virtual package (see
4955 <ref id=
"mail-transport-agents">), all packages providing that
4956 virtual package should also declare a conflict with it
4957 using
<tt>Conflicts
</tt>. This will ensure that at most one
4958 provider of that virtual package is unpacked or installed at a
4963 <sect id=
"replaces"><heading>Overwriting files and replacing
4964 packages -
<tt>Replaces
</tt></heading>
4967 Packages can declare in their control file that they should
4968 overwrite files in certain other packages, or completely replace
4969 other packages. The
<tt>Replaces
</tt> control field has these
4970 two distinct purposes.
4973 <sect1><heading>Overwriting files in other packages
</heading>
4976 It is usually an error for a package to contain files which
4977 are on the system in another package. However, if the
4978 overwriting package declares that it
<tt>Replaces
</tt> the one
4979 containing the file being overwritten, then
<prgn>dpkg
</prgn>
4980 will replace the file from the old package with that from the
4981 new. The file will no longer be listed as
"owned" by the old
4982 package and will be taken over by the new package.
4983 Normally,
<tt>Breaks
</tt> should be used in conjunction
4984 with
<tt>Replaces
</tt>.
<footnote>
4985 To see why
<tt>Breaks
</tt> is normally needed in addition
4986 to
<tt>Replaces
</tt>, consider the case of a file in the
4987 package
<package>foo
</package> being taken over by the
4988 package
<package>foo-data
</package>.
4989 <tt>Replaces
</tt> will allow
<package>foo-data
</package> to
4990 be installed and take over that file. However,
4991 without
<tt>Breaks
</tt>, nothing
4992 requires
<package>foo
</package> to be upgraded to a newer
4993 version that knows it does not include that file and instead
4994 depends on
<package>foo-data
</package>. Nothing would
4995 prevent the new
<package>foo-data
</package> package from
4996 being installed and then removed, removing the file that it
4997 took over from
<package>foo
</package>. After that
4998 operation, the package manager would think the system was in
4999 a consistent state, but the
<package>foo
</package> package
5000 would be missing one of its files.
5005 For example, if a package
<package>foo
</package> is split
5006 into
<package>foo
</package> and
<package>foo-data
</package>
5007 starting at version
1.2-
3,
<package>foo-data
</package> would
5009 <example compact=
"compact">
5010 Replaces: foo (
<< 1.2-
3)
5011 Breaks: foo (
<< 1.2-
3)
5013 in its control file. The new version of the
5014 package
<package>foo
</package> would normally have the field
5015 <example compact=
"compact">
5016 Depends: foo-data (
>=
1.2-
3)
5018 (or possibly
<tt>Recommends
</tt> or even
<tt>Suggests
</tt> if
5019 the files moved into
<package>foo-data
</package> are not
5020 required for normal operation).
5024 If a package is completely replaced in this way, so that
5025 <prgn>dpkg
</prgn> does not know of any files it still
5026 contains, it is considered to have
"disappeared". It will
5027 be marked as not wanted on the system (selected for
5028 removal) and not installed. Any
<tt>conffile
</tt>s
5029 details noted for the package will be ignored, as they
5030 will have been taken over by the overwriting package. The
5031 package's
<prgn>postrm
</prgn> script will be run with a
5032 special argument to allow the package to do any final
5033 cleanup required. See
<ref id=
"mscriptsinstact">.
5035 Replaces is a one way relationship. You have to install
5036 the replacing package after the replaced package.
5041 For this usage of
<tt>Replaces
</tt>, virtual packages (see
5042 <ref id=
"virtual">) are not considered when looking at a
5043 <tt>Replaces
</tt> field. The packages declared as being
5044 replaced must be mentioned by their real names.
5048 This usage of
<tt>Replaces
</tt> only takes effect when both
5049 packages are at least partially on the system at once. It is
5050 not relevant if the packages conflict unless the conflict has
5055 <sect1><heading>Replacing whole packages, forcing their
5059 Second,
<tt>Replaces
</tt> allows the packaging system to
5060 resolve which package should be removed when there is a
5061 conflict (see
<ref id=
"conflicts">). This usage only takes
5062 effect when the two packages
<em>do
</em> conflict, so that the
5063 two usages of this field do not interfere with each other.
5067 In this situation, the package declared as being replaced
5068 can be a virtual package, so for example, all mail
5069 transport agents (MTAs) would have the following fields in
5070 their control files:
5071 <example compact=
"compact">
5072 Provides: mail-transport-agent
5073 Conflicts: mail-transport-agent
5074 Replaces: mail-transport-agent
5076 ensuring that only one MTA can be installed at any one
5077 time. See
<ref id=
"virtual"> for more information about this
5082 <sect id=
"sourcebinarydeps">
5083 <heading>Relationships between source and binary packages -
5084 <tt>Build-Depends
</tt>,
<tt>Build-Depends-Indep
</tt>,
5085 <tt>Build-Conflicts
</tt>,
<tt>Build-Conflicts-Indep
</tt>
5089 Source packages that require certain binary packages to be
5090 installed or absent at the time of building the package
5091 can declare relationships to those binary packages.
5095 This is done using the
<tt>Build-Depends
</tt>,
5096 <tt>Build-Depends-Indep
</tt>,
<tt>Build-Conflicts
</tt> and
5097 <tt>Build-Conflicts-Indep
</tt> control fields.
5101 Build-dependencies on
"build-essential" binary packages can be
5102 omitted. Please see
<ref id=
"pkg-relations"> for more information.
5106 The dependencies and conflicts they define must be satisfied
5107 (as defined earlier for binary packages) in order to invoke
5108 the targets in
<tt>debian/rules
</tt>, as follows:
<footnote>
5110 There is no Build-Depends-Arch; this role is essentially
5111 met with Build-Depends. Anyone building the
5112 <tt>build-indep
</tt> and
<tt>binary-indep
</tt> targets is
5113 assumed to be building the whole package, and therefore
5114 installation of all build dependencies is required.
5117 The autobuilders use
<tt>dpkg-buildpackage -B
</tt>, which
5118 calls
<tt>build
</tt>, not
<tt>build-arch
</tt> since it does
5119 not yet know how to check for its existence, and
5120 <tt>binary-arch
</tt>. The purpose of the original split
5121 between
<tt>Build-Depends
</tt> and
5122 <tt>Build-Depends-Indep
</tt> was so that the autobuilders
5123 wouldn't need to install extra packages needed only for the
5124 binary-indep targets. But without a build-arch/build-indep
5125 split, this didn't work, since most of the work is done in
5126 the build target, not in the binary target.
5130 <tag><tt>clean
</tt>,
<tt>build-arch
</tt>, and
5131 <tt>binary-arch
</tt></tag>
5133 Only the
<tt>Build-Depends
</tt> and
<tt>Build-Conflicts
</tt>
5134 fields must be satisfied when these targets are invoked.
5136 <tag><tt>build
</tt>,
<tt>build-indep
</tt>,
<tt>binary
</tt>,
5137 and
<tt>binary-indep
</tt></tag>
5139 The
<tt>Build-Depends
</tt>,
<tt>Build-Conflicts
</tt>,
5140 <tt>Build-Depends-Indep
</tt>, and
5141 <tt>Build-Conflicts-Indep
</tt> fields must be satisfied when
5142 these targets are invoked.
5150 <chapt id=
"sharedlibs"><heading>Shared libraries
</heading>
5153 Packages containing shared libraries must be constructed with
5154 a little care to make sure that the shared library is always
5155 available. This is especially important for packages whose
5156 shared libraries are vitally important, such as the C library
5157 (currently
<tt>libc6
</tt>).
5161 This section deals only with public shared libraries: shared
5162 libraries that are placed in directories searched by the dynamic
5163 linker by default or which are intended to be linked against
5164 normally and possibly used by other, independent packages. Shared
5165 libraries that are internal to a particular package or that are
5166 only loaded as dynamic modules are not covered by this section and
5167 are not subject to its requirements.
5171 A shared library is identified by the
<tt>SONAME
</tt> attribute
5172 stored in its dynamic section. When a binary is linked against a
5173 shared library, the
<tt>SONAME
</tt> of the shared library is
5174 recorded in the binary's
<tt>NEEDED
</tt> section so that the
5175 dynamic linker knows that library must be loaded at runtime. The
5176 shared library file's full name (which usually contains additional
5177 version information not needed in the
<tt>SONAME
</tt>) is
5178 therefore normally not referenced directly. Instead, the shared
5179 library is loaded by its
<tt>SONAME
</tt>, which exists on the file
5180 system as a symlink pointing to the full name of the shared
5181 library. This symlink must be provided by the
5182 package.
<ref id=
"sharedlibs-runtime"> describes how to do this.
5184 This is a convention of shared library versioning, but not a
5185 requirement. Some libraries use the
<tt>SONAME
</tt> as the full
5186 library file name instead and therefore do not need a symlink.
5187 Most, however, encode additional information about
5188 backwards-compatible revisions as a minor version number in the
5189 file name. The
<tt>SONAME
</tt> itself only changes when
5190 binaries linked with the earlier version of the shared library
5191 may no longer work, but the filename may change with each
5192 release of the library. See
<ref id=
"sharedlibs-runtime"> for
5198 When linking a binary or another shared library against a shared
5199 library, the
<tt>SONAME
</tt> for that shared library is not yet
5200 known. Instead, the shared library is found by looking for a file
5201 matching the library name with
<tt>.so
</tt> appended. This file
5202 exists on the file system as a symlink pointing to the shared
5207 Shared libraries are normally split into several binary packages.
5208 The
<tt>SONAME
</tt> symlink is installed by the runtime shared
5209 library package, and the bare
<tt>.so
</tt> symlink is installed in
5210 the development package since it's only used when linking binaries
5211 or shared libraries. However, there are some exceptions for
5212 unusual shared libraries or for shared libraries that are also
5213 loaded as dynamic modules by other programs.
5217 This section is primarily concerned with how the separation of
5218 shared libraries into multiple packages should be done and how
5219 dependencies on and between shared library binary packages are
5220 managed in Debian.
<ref id=
"libraries"> should be read in
5221 conjunction with this section and contains additional rules for
5222 the files contained in the shared library packages.
5225 <sect id=
"sharedlibs-runtime">
5226 <heading>Run-time shared libraries
</heading>
5229 The run-time shared library must be placed in a package
5230 whose name changes whenever the
<tt>SONAME
</tt> of the shared
5231 library changes. This allows several versions of the shared
5232 library to be installed at the same time, allowing installation
5233 of the new version of the shared library without immediately
5234 breaking binaries that depend on the old version. Normally, the
5235 run-time shared library and its
<tt>SONAME
</tt> symlink should
5236 be placed in a package named
5237 <package><var>libraryname
</var><var>soversion
</var></package>,
5238 where
<var>soversion
</var> is the version number in
5239 the
<tt>SONAME
</tt> of the shared library.
5240 See
<ref id=
"shlibs"> for detailed information on how to
5241 determine this version. Alternatively, if it would be confusing
5242 to directly append
<var>soversion
</var>
5243 to
<var>libraryname
</var> (if, for example,
<var>libraryname
</var>
5244 itself ends in a number), you should use
5245 <package><var>libraryname
</var>-
<var>soversion
</var></package>
5250 If you have several shared libraries built from the same source
5251 tree, you may lump them all together into a single shared
5252 library package provided that all of their
<tt>SONAME
</tt>s will
5253 always change together. Be aware that this is not normally the
5254 case, and if the
<tt>SONAME
</tt>s do not change together,
5255 upgrading such a merged shared library package will be
5256 unnecessarily difficult because of file conflicts with the old
5257 version of the package. When in doubt, always split shared
5258 library packages so that each binary package installs a single
5263 Every time the shared library ABI changes in a way that may
5264 break binaries linked against older versions of the shared
5265 library, the
<tt>SONAME
</tt> of the library and the
5266 corresponding name for the binary package containing the runtime
5267 shared library should change. Normally, this means
5268 the
<tt>SONAME
</tt> should change any time an interface is
5269 removed from the shared library or the signature of an interface
5270 (the number of parameters or the types of parameters that it
5271 takes, for example) is changed. This practice is vital to
5272 allowing clean upgrades from older versions of the package and
5273 clean transitions between the old ABI and new ABI without having
5274 to upgrade every affected package simultaneously.
5278 The
<tt>SONAME
</tt> and binary package name need not, and indeed
5279 normally should not, change if new interfaces are added but none
5280 are removed or changed, since this will not break binaries
5281 linked against the old shared library. Correct versioning of
5282 dependencies on the newer shared library by binaries that use
5283 the new interfaces is handled via
5284 the
<qref id=
"sharedlibs-shlibdeps"><tt>shlibs
</tt>
5285 system
</qref> or via symbols files (see
5286 <manref name=
"deb-symbols" section=
"5">).
5290 The package should install the shared libraries under
5291 their normal names. For example, the
<package>libgdbm3
</package>
5292 package should install
<file>libgdbm.so
.3.0.0</file> as
5293 <file>/usr/lib/libgdbm.so
.3.0.0</file>. The files should not be
5294 renamed or re-linked by any
<prgn>prerm
</prgn> or
5295 <prgn>postrm
</prgn> scripts;
<prgn>dpkg
</prgn> will take care
5296 of renaming things safely without affecting running programs,
5297 and attempts to interfere with this are likely to lead to
5302 Shared libraries should not be installed executable, since
5303 the dynamic linker does not require this and trying to
5304 execute a shared library usually results in a core dump.
5308 The run-time library package should include the symbolic link for
5309 the
<tt>SONAME
</tt> that
<prgn>ldconfig
</prgn> would create for
5310 the shared libraries. For example,
5311 the
<package>libgdbm3
</package> package should include a symbolic
5312 link from
<file>/usr/lib/libgdbm.so
.3</file> to
5313 <file>libgdbm.so
.3.0.0</file>. This is needed so that the dynamic
5314 linker (for example
<prgn>ld.so
</prgn> or
5315 <prgn>ld-linux.so.*
</prgn>) can find the library between the
5316 time that
<prgn>dpkg
</prgn> installs it and the time that
5317 <prgn>ldconfig
</prgn> is run in the
<prgn>postinst
</prgn>
5319 The package management system requires the library to be
5320 placed before the symbolic link pointing to it in the
5321 <file>.deb
</file> file. This is so that when
5322 <prgn>dpkg
</prgn> comes to install the symlink
5323 (overwriting the previous symlink pointing at an older
5324 version of the library), the new shared library is already
5325 in place. In the past, this was achieved by creating the
5326 library in the temporary packaging directory before
5327 creating the symlink. Unfortunately, this was not always
5328 effective, since the building of the tar file in the
5329 <file>.deb
</file> depended on the behavior of the underlying
5330 file system. Some file systems (such as reiserfs) reorder
5331 the files so that the order of creation is forgotten.
5332 Since version
1.7.0,
<prgn>dpkg
</prgn>
5333 reorders the files itself as necessary when building a
5334 package. Thus it is no longer important to concern
5335 oneself with the order of file creation.
5339 <sect1 id=
"ldconfig">
5340 <heading><tt>ldconfig
</tt></heading>
5343 Any package installing shared libraries in one of the default
5344 library directories of the dynamic linker (which are currently
5345 <file>/usr/lib
</file> and
<file>/lib
</file>) or a directory that is
5346 listed in
<file>/etc/ld.so.conf
</file><footnote>
5348 <list compact=
"compact">
5349 <item>/usr/local/lib
</item>
5350 <item>/usr/lib/libc5-compat
</item>
5351 <item>/lib/libc5-compat
</item>
5354 must use
<prgn>ldconfig
</prgn> to update the shared library
5359 The package maintainer scripts must only call
5360 <prgn>ldconfig
</prgn> under these circumstances:
5361 <list compact=
"compact">
5362 <item>When the
<prgn>postinst
</prgn> script is run with a
5363 first argument of
<tt>configure
</tt>, the script must call
5364 <prgn>ldconfig
</prgn>, and may optionally invoke
5365 <prgn>ldconfig
</prgn> at other times.
5367 <item>When the
<prgn>postrm
</prgn> script is run with a
5368 first argument of
<tt>remove
</tt>, the script should call
5369 <prgn>ldconfig
</prgn>.
5374 During install or upgrade, the preinst is called before
5375 the new files are installed, so calling
"ldconfig" is
5376 pointless. The preinst of an existing package can also be
5377 called if an upgrade fails. However, this happens during
5378 the critical time when a shared libs may exist on-disk
5379 under a temporary name. Thus, it is dangerous and
5380 forbidden by current policy to call
"ldconfig" at this
5385 When a package is installed or upgraded,
"postinst
5386 configure" runs after the new files are safely on-disk.
5387 Since it is perfectly safe to invoke ldconfig
5388 unconditionally in a postinst, it is OK for a package to
5389 simply put ldconfig in its postinst without checking the
5390 argument. The postinst can also be called to recover from
5391 a failed upgrade. This happens before any new files are
5392 unpacked, so there is no reason to call
"ldconfig" at this
5397 For a package that is being removed, prerm is
5398 called with all the files intact, so calling ldconfig is
5399 useless. The other calls to
"prerm" happen in the case of
5400 upgrade at a time when all the files of the old package
5401 are on-disk, so again calling
"ldconfig" is pointless.
5405 postrm, on the other hand, is called with the
"remove"
5406 argument just after the files are removed, so this is
5407 the proper time to call
"ldconfig" to notify the system
5408 of the fact that the shared libraries from the package
5409 are removed. The postrm can be called at several other
5410 times. At the time of
"postrm purge",
"postrm
5411 abort-install", or
"postrm abort-upgrade", calling
5412 "ldconfig" is useless because the shared lib files are
5413 not on-disk. However, when
"postrm" is invoked with
5414 arguments
"upgrade",
"failed-upgrade", or
"disappear", a
5415 shared lib may exist on-disk under a temporary filename.
5423 <sect id=
"sharedlibs-support-files">
5424 <heading>Shared library support files
</heading>
5427 If your package contains files whose names do not change with
5428 each change in the library shared object version, you must not
5429 put them in the shared library package. Otherwise, several
5430 versions of the shared library cannot be installed at the same
5431 time without filename clashes, making upgrades and transitions
5432 unnecessarily difficult.
5436 It is recommended that supporting files and run-time support
5437 programs that do not need to be invoked manually by users, but
5438 are nevertheless required for the package to function, be placed
5439 (if they are binary) in a subdirectory of
<file>/usr/lib
</file>,
5440 preferably under
<file>/usr/lib/
</file><var>package-name
</var>.
5441 If the program or file is architecture independent, the
5442 recommendation is for it to be placed in a subdirectory of
5443 <file>/usr/share
</file> instead, preferably under
5444 <file>/usr/share/
</file><var>package-name
</var>. Following the
5445 <var>package-name
</var> naming convention ensures that the file
5446 names change when the shared object version changes.
5450 Run-time support programs that use the shared library but are
5451 not required for the library to function or files used by the
5452 shared library that can be used by any version of the shared
5453 library package should instead be put in a separate package.
5454 This package might typically be named
5455 <package><var>libraryname
</var>-tools
</package>; note the
5456 absence of the
<var>soversion
</var> in the package name.
5460 Files and support programs only useful when compiling software
5461 against the library should be included in the development
5462 package for the library.
<footnote>
5463 For example, a
<file><var>package-name
</var>-config
</file>
5464 script or
<package>pkg-config
</package> configuration files.
5469 <sect id=
"sharedlibs-static">
5470 <heading>Static libraries
</heading>
5473 The static library (
<file><var>libraryname.a
</var></file>)
5474 is usually provided in addition to the shared version.
5475 It is placed into the development package (see below).
5479 In some cases, it is acceptable for a library to be
5480 available in static form only; these cases include:
5482 <item>libraries for languages whose shared library support
5483 is immature or unstable
</item>
5484 <item>libraries whose interfaces are in flux or under
5485 development (commonly the case when the library's
5486 major version number is zero, or where the ABI breaks
5487 across patchlevels)
</item>
5488 <item>libraries which are explicitly intended to be
5489 available only in static form by their upstream
5494 <sect id=
"sharedlibs-dev">
5495 <heading>Development files
</heading>
5498 If there are development files associated with a shared library,
5499 the source package needs to generate a binary development package
5500 named
<package><var>libraryname
</var><var>soversion
</var>-dev
</package>,
5501 or if you prefer only to support one development version at a
5502 time,
<package><var>libraryname
</var>-dev
</package>. Installing
5503 the development package must result in installation of all the
5504 development files necessary for compiling programs against that
5505 shared library.
<footnote>
5506 This wording allows the development files to be split into
5507 several packages, such as a separate architecture-independent
5508 <package><var>libraryname
</var>-headers
</package>, provided that
5509 the development package depends on all the required additional
5515 In case several development versions of a library exist, you may
5516 need to use
<prgn>dpkg
</prgn>'s Conflicts mechanism (see
5517 <ref id=
"conflicts">) to ensure that the user only installs one
5518 development version at a time (as different development versions are
5519 likely to have the same header files in them, which would cause a
5520 filename clash if both were installed).
5524 The development package should contain a symlink for the associated
5525 shared library without a version number. For example, the
5526 <package>libgdbm-dev
</package> package should include a symlink
5527 from
<file>/usr/lib/libgdbm.so
</file> to
5528 <file>libgdbm.so
.3.0.0</file>. This symlink is needed by the linker
5529 (
<prgn>ld
</prgn>) when compiling packages, as it will only look for
5530 <file>libgdbm.so
</file> when compiling dynamically.
5534 <sect id=
"sharedlibs-intradeps">
5535 <heading>Dependencies between the packages of the same library
</heading>
5538 Typically the development version should have an exact
5539 version dependency on the runtime library, to make sure that
5540 compilation and linking happens correctly. The
5541 <tt>${binary:Version}
</tt> substitution variable can be
5542 useful for this purpose.
5544 Previously,
<tt>${Source-Version}
</tt> was used, but its name
5545 was confusing and it has been deprecated since dpkg
1.13.19.
5550 <sect id=
"sharedlibs-shlibdeps">
5551 <heading>Dependencies between the library and other packages -
5552 the
<tt>shlibs
</tt> system
</heading>
5555 If a package contains a binary or library which links to a
5556 shared library, we must ensure that when the package is
5557 installed on the system, all of the libraries needed are
5558 also installed. This requirement led to the creation of the
5559 <tt>shlibs
</tt> system, which is very simple in its design:
5560 any package which
<em>provides
</em> a shared library also
5561 provides information on the package dependencies required to
5562 ensure the presence of this library, and any package which
5563 <em>uses
</em> a shared library uses this information to
5564 determine the dependencies it requires. The files which
5565 contain the mapping from shared libraries to the necessary
5566 dependency information are called
<file>shlibs
</file> files.
5570 When a package is built which contains any shared libraries, it
5571 must provide a
<file>shlibs
</file> file for other packages to
5572 use. When a package is built which contains any shared
5573 libraries or compiled binaries, it must run
5574 <qref id=
"pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps
</prgn></qref>
5575 on these to determine the libraries used and hence the
5576 dependencies needed by this package.
<footnote>
5578 <prgn>dpkg-shlibdeps
</prgn> will use a program
5579 like
<prgn>objdump
</prgn> or
<prgn>readelf
</prgn> to find
5580 the libraries directly needed by the binaries or shared
5581 libraries in the package.
5585 We say that a binary
<tt>foo
</tt> <em>directly
</em> uses
5586 a library
<tt>libbar
</tt> if it is explicitly linked
5587 with that library (that is, the library is listed in the ELF
5588 <tt>NEEDED
</tt> attribute, caused by adding
<tt>-lbar
</tt>
5589 to the link line when the binary is created). Other
5590 libraries that are needed by
<tt>libbar
</tt> are linked
5591 <em>indirectly
</em> to
<tt>foo
</tt>, and the dynamic
5592 linker will load them automatically when it loads
5593 <tt>libbar
</tt>. A package should depend on the libraries
5594 it directly uses, but not the libraries it indirectly uses.
5595 The dependencies for those libraries will automatically pull
5596 in the other libraries.
5600 A good example of where this helps is the following. We
5601 could update
<tt>libimlib
</tt> with a new version that
5602 supports a new graphics format called dgf (but retaining the
5603 same major version number) and depends on
<tt>libdgf
</tt>.
5604 If we used
<prgn>ldd
</prgn> to add dependencies for every
5605 library directly or indirectly linked with a binary, every
5606 package that uses
<tt>libimlib
</tt> would need to be
5607 recompiled so it would also depend on
<tt>libdgf
</tt> or it
5608 wouldn't run due to missing symbols. Since dependencies are
5609 only added based on ELF
<tt>NEEDED
</tt> attribute, packages
5610 using
<tt>libimlib
</tt> can rely on
<tt>libimlib
</tt> itself
5611 having the dependency on
<tt>libdgf
</tt> and so they would
5612 not need rebuilding.
5618 In the following sections, we will first describe where the
5619 various
<tt>shlibs
</tt> files are to be found, then how to
5620 use
<prgn>dpkg-shlibdeps
</prgn>, and finally the
<tt>shlibs
</tt>
5621 file format and how to create them if your package contains a
5626 <heading>The
<tt>shlibs
</tt> files present on the system
</heading>
5629 There are several places where
<tt>shlibs
</tt> files are
5630 found. The following list gives them in the order in which
5632 <qref id=
"pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps
</prgn></qref>.
5633 (The first one which gives the required information is used.)
5639 <p><file>debian/shlibs.local
</file></p>
5642 This lists overrides for this package. This file should
5643 normally not be used, but may be needed temporarily in
5644 unusual situations to work around bugs in other packages,
5645 or in unusual cases where the normally declared dependency
5646 information in the installed
<file>shlibs
</file> file for
5647 a library cannot be used. This file overrides information
5648 obtained from any other source.
5653 <p><file>/etc/dpkg/shlibs.override
</file></p>
5656 This lists global overrides. This list is normally
5657 empty. It is maintained by the local system
5663 <p><file>DEBIAN/shlibs
</file> files in the
"build directory"</p>
5666 When packages are being built,
5667 any
<file>debian/shlibs
</file> files are copied into the
5668 control information file area of the temporary build
5669 directory and given the name
<file>shlibs
</file>. These
5670 files give details of any shared libraries included in the
5671 same package.
<footnote>
5672 An example may help here. Let us say that the source
5673 package
<tt>foo
</tt> generates two binary
5674 packages,
<tt>libfoo2
</tt> and
<tt>foo-runtime
</tt>.
5675 When building the binary packages, the two packages are
5676 created in the directories
<file>debian/libfoo2
</file>
5677 and
<file>debian/foo-runtime
</file> respectively.
5678 (
<file>debian/tmp
</file> could be used instead of one of
5679 these.) Since
<tt>libfoo2
</tt> provides the
5680 <tt>libfoo
</tt> shared library, it will require a
5681 <tt>shlibs
</tt> file, which will be installed in
5682 <file>debian/libfoo2/DEBIAN/shlibs
</file>, eventually to
5683 become
<file>/var/lib/dpkg/info/libfoo2.shlibs
</file>.
5684 When
<prgn>dpkg-shlibdeps
</prgn> is run on the
5685 executable
<file>debian/foo-runtime/usr/bin/foo-prog
</file>,
5687 the
<file>debian/libfoo2/DEBIAN/shlibs
</file> file to
5688 determine whether
<tt>foo-prog
</tt>'s library
5689 dependencies are satisfied by any of the libraries
5690 provided by
<tt>libfoo2
</tt>. For this reason,
5691 <prgn>dpkg-shlibdeps
</prgn> must only be run once all of
5692 the individual binary packages'
<tt>shlibs
</tt> files
5693 have been installed into the build directory.
5699 <p><file>/var/lib/dpkg/info/*.shlibs
</file></p>
5702 These are the
<file>shlibs
</file> files corresponding to
5703 all of the packages installed on the system, and are
5704 maintained by the relevant package maintainers.
5709 <p><file>/etc/dpkg/shlibs.default
</file></p>
5712 This file lists any shared libraries whose packages
5713 have failed to provide correct
<file>shlibs
</file> files.
5714 It was used when the
<file>shlibs
</file> setup was first
5715 introduced, but it is now normally empty. It is
5716 maintained by the
<tt>dpkg
</tt> maintainer.
5724 <heading>How to use
<prgn>dpkg-shlibdeps
</prgn> and the
5725 <file>shlibs
</file> files
</heading>
5729 <qref id=
"pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps
</prgn></qref>
5730 into your
<file>debian/rules
</file> file. If your package
5731 contains only compiled binaries and libraries (but no scripts),
5732 you can use a command such as:
5733 <example compact=
"compact">
5734 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5735 debian/tmp/usr/lib/*
5737 Otherwise, you will need to explicitly list the compiled
5738 binaries and libraries.
<footnote>
5739 If you are using
<tt>debhelper
</tt>, the
5740 <prgn>dh_shlibdeps
</prgn> program will do this work for you.
5741 It will also correctly handle multi-binary packages.
5746 This command puts the dependency information into the
5747 <file>debian/substvars
</file> file, which is then used by
5748 <prgn>dpkg-gencontrol
</prgn>. You will need to place a
5749 <tt>${shlibs:Depends}
</tt> variable in the
<tt>Depends
</tt>
5750 field in the control file for this to work.
5754 If you have multiple binary packages, you will need to call
5755 <prgn>dpkg-shlibdeps
</prgn> on each one which contains
5756 compiled libraries or binaries. In such a case, you will
5757 need to use the
<tt>-T
</tt> option to the
<tt>dpkg
</tt>
5758 utilities to specify a different
<file>substvars
</file> file.
5762 If you are creating a udeb for use in the Debian Installer,
5763 you will need to specify that
<prgn>dpkg-shlibdeps
</prgn>
5764 should use the dependency line of type
<tt>udeb
</tt> by
5765 adding the
<tt>-tudeb
</tt> option
<footnote>
5766 <prgn>dh_shlibdeps
</prgn> from the
<tt>debhelper
</tt> suite
5767 will automatically add this option if it knows it is
5769 </footnote>. If there is no dependency line of
5770 type
<tt>udeb
</tt> in the
<file>shlibs
</file>
5771 file,
<prgn>dpkg-shlibdeps
</prgn> will fall back to the regular
5776 For more details on
<prgn>dpkg-shlibdeps
</prgn>, please see
5777 <ref id=
"pkg-dpkg-shlibdeps"> and
5778 <manref name=
"dpkg-shlibdeps" section=
"1">.
5783 <heading>The
<file>shlibs
</file> File Format
</heading>
5786 Each
<file>shlibs
</file> file has the same format. Lines
5787 beginning with
<tt>#
</tt> are considered to be comments and
5788 are ignored. Each line is of the form:
5789 <example compact=
"compact">
5790 [
<var>type
</var>: ]
<var>library-name
</var> <var>soname-version
</var> <var>dependencies ...
</var>
5795 We will explain this by reference to the example of the
5796 <tt>zlib1g
</tt> package, which (at the time of writing)
5797 installs the shared library
<file>/usr/lib/libz.so
.1.1.3</file>.
5801 <var>type
</var> is an optional element that indicates the type
5802 of package for which the line is valid. The only type currently
5803 in use is
<tt>udeb
</tt>. The colon and space after the type are
5808 <var>library-name
</var> is the name of the shared library,
5809 in this case
<tt>libz
</tt>. (This must match the name part
5810 of the soname, see below.)
5814 <var>soname-version
</var> is the version part of the soname of
5815 the library. The soname is the thing that must exactly match
5816 for the library to be recognized by the dynamic linker, and is
5818 <tt><var>name
</var>.so.
<var>major-version
</var></tt>, in our
5819 example,
<tt>libz.so
.1</tt>.
<footnote>
5820 This can be determined using the command
5821 <example compact=
"compact">
5822 objdump -p /usr/lib/libz.so
.1.1.3 | grep SONAME
5825 The version part is the part which comes after
5826 <tt>.so.
</tt>, so in our case, it is
<tt>1</tt>. The soname may
5827 instead be of the form
5828 <tt><var>name
</var>-
<var>major-version
</var>.so
</tt>, such
5829 as
<tt>libdb-
4.8.so
</tt>, in which case the name would
5830 be
<tt>libdb
</tt> and the version would be
<tt>4.8</tt>.
5834 <var>dependencies
</var> has the same syntax as a dependency
5835 field in a binary package control file. It should give
5836 details of which packages are required to satisfy a binary
5837 built against the version of the library contained in the
5838 package. See
<ref id=
"depsyntax"> for details.
5842 In our example, if the first version of the
<tt>zlib1g
</tt>
5843 package which contained a minor number of at least
5844 <tt>1.3</tt> was
<var>1:
1.1.3-
1</var>, then the
5845 <tt>shlibs
</tt> entry for this library could say:
5846 <example compact=
"compact">
5847 libz
1 zlib1g (
>=
1:
1.1.3)
5849 The version-specific dependency is to avoid warnings from
5850 the dynamic linker about using older shared libraries with
5855 As zlib1g also provides a udeb containing the shared library,
5856 there would also be a second line:
5857 <example compact=
"compact">
5858 udeb: libz
1 zlib1g-udeb (
>=
1:
1.1.3)
5864 <heading>Providing a
<file>shlibs
</file> file
</heading>
5867 If your package provides a shared library, you need to create
5868 a
<file>shlibs
</file> file following the format described above.
5869 It is usual to call this file
<file>debian/shlibs
</file> (but if
5870 you have multiple binary packages, you might want to call it
5871 <file>debian/shlibs.
<var>package
</var></file> instead). Then
5872 let
<file>debian/rules
</file> install it in the control
5873 information file area:
5874 <example compact=
"compact">
5875 install -m644 debian/shlibs debian/tmp/DEBIAN
5877 or, in the case of a multi-binary package:
5878 <example compact=
"compact">
5879 install -m644 debian/shlibs.
<var>package
</var> debian/
<var>package
</var>/DEBIAN/shlibs
5881 An alternative way of doing this is to create the
5882 <file>shlibs
</file> file in the control information file area
5883 directly from
<file>debian/rules
</file> without using
5884 a
<file>debian/shlibs
</file> file at all,
<footnote>
5885 This is what
<prgn>dh_makeshlibs
</prgn> in
5886 the
<package>debhelper
</package> suite does. If your package
5887 also has a udeb that provides a shared
5888 library,
<prgn>dh_makeshlibs
</prgn> can automatically generate
5889 the
<tt>udeb:
</tt> lines if you specify the name of the udeb
5890 with the
<tt>--add-udeb
</tt> option.
5892 since the
<file>debian/shlibs
</file> file itself is ignored by
5893 <prgn>dpkg-shlibdeps
</prgn>.
5897 As
<prgn>dpkg-shlibdeps
</prgn> reads the
5898 <file>DEBIAN/shlibs
</file> files in all of the binary packages
5899 being built from this source package, all of the
5900 <file>DEBIAN/shlibs
</file> files should be installed before
5901 <prgn>dpkg-shlibdeps
</prgn> is called on any of the binary
5909 <chapt id=
"opersys"><heading>The Operating System
</heading>
5912 <heading>File system hierarchy
</heading>
5916 <heading>File System Structure
</heading>
5919 The location of all installed files and directories must
5920 comply with the Filesystem Hierarchy Standard (FHS),
5921 version
2.3, with the exceptions noted below, and except
5922 where doing so would violate other terms of Debian
5923 Policy. The following exceptions to the FHS apply:
5928 The optional rules related to user specific
5929 configuration files for applications are stored in
5930 the user's home directory are relaxed. It is
5931 recommended that such files start with the
5932 '
<tt>.
</tt>' character (a
"dot file"), and if an
5933 application needs to create more than one dot file
5934 then the preferred placement is in a subdirectory
5935 with a name starting with a '.' character, (a
"dot
5936 directory"). In this case it is recommended the
5937 configuration files not start with the '.'
5943 The requirement for amd64 to use
<file>/lib64
</file>
5944 for
64 bit binaries is removed.
5949 The requirement for object files, internal binaries, and
5950 libraries, including
<file>libc.so.*
</file>, to be located
5951 directly under
<file>/lib{,
32}
</file> and
5952 <file>/usr/lib{,
32}
</file> is amended, permitting files
5953 to instead be installed to
5954 <file>/lib/
<var>triplet
</var></file> and
5955 <file>/usr/lib/
<var>triplet
</var></file>, where
5956 <tt><var>triplet
</var></tt> is the value returned by
5957 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE
</tt> for the
5958 architecture of the package. Packages may
<em>not
</em>
5959 install files to any
<var>triplet
</var> path other
5960 than the one matching the architecture of that package;
5961 for instance, an
<tt>Architecture: amd64
</tt> package
5962 containing
32-bit x86 libraries may not install these
5963 libraries to
<file>/usr/lib/i486-linux-gnu
</file>.
5965 This is necessary in order to reserve the directories for
5966 use in cross-installation of library packages from other
5967 architectures, as part of the planned deployment of
5972 Applications may also use a single subdirectory under
5973 <file>/usr/lib/
<var>triplet
</var></file>.
5976 The execution time linker/loader, ld*, must still be made
5977 available in the existing location under /lib or /lib64
5978 since this is part of the ELF ABI for the architecture.
5983 The requirement that
5984 <file>/usr/local/share/man
</file> be
"synonymous"
5985 with
<file>/usr/local/man
</file> is relaxed to a
5990 The requirement that windowmanagers with a single
5991 configuration file call it
<file>system.*wmrc
</file>
5992 is removed, as is the restriction that the window
5993 manager subdirectory be named identically to the
5994 window manager name itself.
5999 The requirement that boot manager configuration
6000 files live in
<file>/etc
</file>, or at least are
6001 symlinked there, is relaxed to a recommendation.
6006 The following directories in the root filesystem are
6007 additionally allowed:
<file>/sys
</file> and
6008 <file>/selinux
</file>.
<footnote>These directories
6009 are used as mount points to mount virtual filesystems
6010 to get access to kernel information.
</footnote>
6017 The version of this document referred here can be
6018 found in the
<tt>debian-policy
</tt> package or on
<url
6019 id=
"http://www.debian.org/doc/packaging-manuals/fhs/"
6020 name=
"FHS (Debian copy)"> alongside this manual (or, if
6021 you have the
<package>debian-policy
</package> installed,
6023 id=
"file:///usr/share/doc/debian-policy/fhs/" name=
"FHS
6024 (local copy)">). The
6025 latest version, which may be a more recent version, may
6027 <url id=
"http://www.pathname.com/fhs/" name=
"FHS (upstream)">.
6028 Specific questions about following the standard may be
6029 asked on the
<tt>debian-devel
</tt> mailing list, or
6030 referred to the FHS mailing list (see the
6031 <url id=
"http://www.pathname.com/fhs/" name=
"FHS web site"> for
6037 <heading>Site-specific programs
</heading>
6040 As mandated by the FHS, packages must not place any
6041 files in
<file>/usr/local
</file>, either by putting them in
6042 the file system archive to be unpacked by
<prgn>dpkg
</prgn>
6043 or by manipulating them in their maintainer scripts.
6047 However, the package may create empty directories below
6048 <file>/usr/local
</file> so that the system administrator knows
6049 where to place site-specific files. These are not
6050 directories
<em>in
</em> <file>/usr/local
</file>, but are
6051 children of directories in
<file>/usr/local
</file>. These
6052 directories (
<file>/usr/local/*/dir/
</file>)
6053 should be removed on package removal if they are
6058 Note that this applies only to
6059 directories
<em>below
</em> <file>/usr/local
</file>,
6060 not
<em>in
</em> <file>/usr/local
</file>. Packages must
6061 not create sub-directories in the
6062 directory
<file>/usr/local
</file> itself, except those
6063 listed in FHS, section
4.5. However, you may create
6064 directories below them as you wish. You must not remove
6065 any of the directories listed in
4.5, even if you created
6070 Since
<file>/usr/local
</file> can be mounted read-only from a
6071 remote server, these directories must be created and
6072 removed by the
<prgn>postinst
</prgn> and
<prgn>prerm
</prgn>
6073 maintainer scripts and not be included in the
6074 <file>.deb
</file> archive. These scripts must not fail if
6075 either of these operations fail.
6079 For example, the
<tt>emacsen-common
</tt> package could
6080 contain something like
6081 <example compact=
"compact">
6082 if [ ! -e /usr/local/share/emacs ]
6084 if mkdir /usr/local/share/emacs
2>/dev/null
6086 chown root:staff /usr/local/share/emacs
6087 chmod
2775 /usr/local/share/emacs
6091 in its
<prgn>postinst
</prgn> script, and
6092 <example compact=
"compact">
6093 rmdir /usr/local/share/emacs/site-lisp
2>/dev/null || true
6094 rmdir /usr/local/share/emacs
2>/dev/null || true
6096 in the
<prgn>prerm
</prgn> script. (Note that this form is
6097 used to ensure that if the script is interrupted, the
6098 directory
<file>/usr/local/share/emacs
</file> will still be
6103 If you do create a directory in
<file>/usr/local
</file> for
6104 local additions to a package, you should ensure that
6105 settings in
<file>/usr/local
</file> take precedence over the
6106 equivalents in
<file>/usr
</file>.
6110 However, because
<file>/usr/local
</file> and its contents are
6111 for exclusive use of the local administrator, a package
6112 must not rely on the presence or absence of files or
6113 directories in
<file>/usr/local
</file> for normal operation.
6117 The
<file>/usr/local
</file> directory itself and all the
6118 subdirectories created by the package should (by default) have
6119 permissions
2775 (group-writable and set-group-id) and be
6120 owned by
<tt>root:staff
</tt>.
6125 <heading>The system-wide mail directory
</heading>
6127 The system-wide mail directory
6128 is
<file>/var/mail
</file>. This directory is part of the
6129 base system and should not be owned by any particular mail
6130 agents. The use of the old
6131 location
<file>/var/spool/mail
</file> is deprecated, even
6132 though the spool may still be physically located there.
6138 <heading>Users and groups
</heading>
6141 <heading>Introduction
</heading>
6143 The Debian system can be configured to use either plain or
6148 Some user ids (UIDs) and group ids (GIDs) are reserved
6149 globally for use by certain packages. Because some
6150 packages need to include files which are owned by these
6151 users or groups, or need the ids compiled into binaries,
6152 these ids must be used on any Debian system only for the
6153 purpose for which they are allocated. This is a serious
6154 restriction, and we should avoid getting in the way of
6155 local administration policies. In particular, many sites
6156 allocate users and/or local system groups starting at
100.
6160 Apart from this we should have dynamically allocated ids,
6161 which should by default be arranged in some sensible
6162 order, but the behavior should be configurable.
6166 Packages other than
<tt>base-passwd
</tt> must not modify
6167 <file>/etc/passwd
</file>,
<file>/etc/shadow
</file>,
6168 <file>/etc/group
</file> or
<file>/etc/gshadow
</file>.
6173 <heading>UID and GID classes
</heading>
6175 The UID and GID numbers are divided into classes as
6181 Globally allocated by the Debian project, the same
6182 on every Debian system. These ids will appear in
6183 the
<file>passwd
</file> and
<file>group
</file> files of all
6184 Debian systems, new ids in this range being added
6185 automatically as the
<tt>base-passwd
</tt> package is
6190 Packages which need a single statically allocated
6191 uid or gid should use one of these; their
6192 maintainers should ask the
<tt>base-passwd
</tt>
6200 Dynamically allocated system users and groups.
6201 Packages which need a user or group, but can have
6202 this user or group allocated dynamically and
6203 differently on each system, should use
<tt>adduser
6204 --system
</tt> to create the group and/or user.
6205 <prgn>adduser
</prgn> will check for the existence of
6206 the user or group, and if necessary choose an unused
6207 id based on the ranges specified in
6208 <file>adduser.conf
</file>.
6212 <tag>1000-
59999:
</tag>
6215 Dynamically allocated user accounts. By default
6216 <prgn>adduser
</prgn> will choose UIDs and GIDs for
6217 user accounts in this range, though
6218 <file>adduser.conf
</file> may be used to modify this
6223 <tag>60000-
64999:
</tag>
6226 Globally allocated by the Debian project, but only
6227 created on demand. The ids are allocated centrally
6228 and statically, but the actual accounts are only
6229 created on users' systems on demand.
6233 These ids are for packages which are obscure or
6234 which require many statically-allocated ids. These
6235 packages should check for and create the accounts in
6236 <file>/etc/passwd
</file> or
<file>/etc/group
</file> (using
6237 <prgn>adduser
</prgn> if it has this facility) if
6238 necessary. Packages which are likely to require
6239 further allocations should have a
"hole" left after
6240 them in the allocation, to give them room to
6245 <tag>65000-
65533:
</tag>
6253 User
<tt>nobody
</tt>. The corresponding gid refers
6254 to the group
<tt>nogroup
</tt>.
6261 <tt>(uid_t)(-
1) == (gid_t)(-
1)
</tt> <em>must
6262 not
</em> be used, because it is the error return
6271 <sect id=
"sysvinit">
6272 <heading>System run levels and
<file>init.d
</file> scripts
</heading>
6274 <sect1 id=
"/etc/init.d">
6275 <heading>Introduction
</heading>
6278 The
<file>/etc/init.d
</file> directory contains the scripts
6279 executed by
<prgn>init
</prgn> at boot time and when the
6280 init state (or
"runlevel") is changed (see
<manref
6281 name=
"init" section=
"8">).
6285 There are at least two different, yet functionally
6286 equivalent, ways of handling these scripts. For the sake
6287 of simplicity, this document describes only the symbolic
6288 link method. However, it must not be assumed by maintainer
6289 scripts that this method is being used, and any automated
6290 manipulation of the various runlevel behaviors by
6291 maintainer scripts must be performed using
6292 <prgn>update-rc.d
</prgn> as described below and not by
6293 manually installing or removing symlinks. For information
6294 on the implementation details of the other method,
6295 implemented in the
<tt>file-rc
</tt> package, please refer
6296 to the documentation of that package.
6300 These scripts are referenced by symbolic links in the
6301 <file>/etc/rc
<var>n
</var>.d
</file> directories. When changing
6302 runlevels,
<prgn>init
</prgn> looks in the directory
6303 <file>/etc/rc
<var>n
</var>.d
</file> for the scripts it should
6304 execute, where
<tt><var>n
</var></tt> is the runlevel that
6305 is being changed to, or
<tt>S
</tt> for the boot-up
6310 The names of the links all have the form
6311 <file>S
<var>mm
</var><var>script
</var></file> or
6312 <file>K
<var>mm
</var><var>script
</var></file> where
6313 <var>mm
</var> is a two-digit number and
<var>script
</var>
6314 is the name of the script (this should be the same as the
6315 name of the actual script in
<file>/etc/init.d
</file>).
6319 When
<prgn>init
</prgn> changes runlevel first the targets
6320 of the links whose names start with a
<tt>K
</tt> are
6321 executed, each with the single argument
<tt>stop
</tt>,
6322 followed by the scripts prefixed with an
<tt>S
</tt>, each
6323 with the single argument
<tt>start
</tt>. (The links are
6324 those in the
<file>/etc/rc
<var>n
</var>.d
</file> directory
6325 corresponding to the new runlevel.) The
<tt>K
</tt> links
6326 are responsible for killing services and the
<tt>S
</tt>
6327 link for starting services upon entering the runlevel.
6331 For example, if we are changing from runlevel
2 to
6332 runlevel
3, init will first execute all of the
<tt>K
</tt>
6333 prefixed scripts it finds in
<file>/etc/rc3.d
</file>, and then
6334 all of the
<tt>S
</tt> prefixed scripts in that directory.
6335 The links starting with
<tt>K
</tt> will cause the
6336 referred-to file to be executed with an argument of
6337 <tt>stop
</tt>, and the
<tt>S
</tt> links with an argument
6342 The two-digit number
<var>mm
</var> is used to determine
6343 the order in which to run the scripts: low-numbered links
6344 have their scripts run first. For example, the
6345 <tt>K20
</tt> scripts will be executed before the
6346 <tt>K30
</tt> scripts. This is used when a certain service
6347 must be started before another. For example, the name
6348 server
<prgn>bind
</prgn> might need to be started before
6349 the news server
<prgn>inn
</prgn> so that
<prgn>inn
</prgn>
6350 can set up its access lists. In this case, the script
6351 that starts
<prgn>bind
</prgn> would have a lower number
6352 than the script that starts
<prgn>inn
</prgn> so that it
6354 <example compact=
"compact">
6361 The two runlevels
0 (halt) and
6 (reboot) are slightly
6362 different. In these runlevels, the links with an
6363 <tt>S
</tt> prefix are still called after those with a
6364 <tt>K
</tt> prefix, but they too are called with the single
6365 argument
<tt>stop
</tt>.
6369 <sect1 id=
"writing-init">
6370 <heading>Writing the scripts
</heading>
6373 Packages that include daemons for system services should
6374 place scripts in
<file>/etc/init.d
</file> to start or stop
6375 services at boot time or during a change of runlevel.
6376 These scripts should be named
6377 <file>/etc/init.d/
<var>package
</var></file>, and they should
6378 accept one argument, saying what to do:
6381 <tag><tt>start
</tt></tag>
6382 <item>start the service,
</item>
6384 <tag><tt>stop
</tt></tag>
6385 <item>stop the service,
</item>
6387 <tag><tt>restart
</tt></tag>
6388 <item>stop and restart the service if it's already running,
6389 otherwise start the service
</item>
6391 <tag><tt>reload
</tt></tag>
6392 <item><p>cause the configuration of the service to be
6393 reloaded without actually stopping and restarting
6396 <tag><tt>force-reload
</tt></tag>
6397 <item>cause the configuration to be reloaded if the
6398 service supports this, otherwise restart the
6402 The
<tt>start
</tt>,
<tt>stop
</tt>,
<tt>restart
</tt>, and
6403 <tt>force-reload
</tt> options should be supported by all
6404 scripts in
<file>/etc/init.d
</file>, the
<tt>reload
</tt>
6409 The
<file>init.d
</file> scripts must ensure that they will
6410 behave sensibly (i.e., returning success and not starting
6411 multiple copies of a service) if invoked with
<tt>start
</tt>
6412 when the service is already running, or with
<tt>stop
</tt>
6413 when it isn't, and that they don't kill unfortunately-named
6414 user processes. The best way to achieve this is usually to
6415 use
<prgn>start-stop-daemon
</prgn> with the
<tt>--oknodo
</tt>
6420 Be careful of using
<tt>set -e
</tt> in
<file>init.d
</file>
6421 scripts. Writing correct
<file>init.d
</file> scripts requires
6422 accepting various error exit statuses when daemons are already
6423 running or already stopped without aborting
6424 the
<file>init.d
</file> script, and common
<file>init.d
</file>
6425 function libraries are not safe to call with
<tt>set -e
</tt>
6427 <tt>/lib/lsb/init-functions
</tt>, which assists in writing
6428 LSB-compliant init scripts, may fail if
<tt>set -e
</tt> is
6429 in effect and echoing status messages to the console fails,
6431 </footnote>. For
<tt>init.d
</tt> scripts, it's often easier
6432 to not use
<tt>set -e
</tt> and instead check the result of
6433 each command separately.
6437 If a service reloads its configuration automatically (as
6438 in the case of
<prgn>cron
</prgn>, for example), the
6439 <tt>reload
</tt> option of the
<file>init.d
</file> script
6440 should behave as if the configuration has been reloaded
6445 The
<file>/etc/init.d
</file> scripts must be treated as
6446 configuration files, either (if they are present in the
6447 package, that is, in the .deb file) by marking them as
6448 <tt>conffile
</tt>s, or, (if they do not exist in the .deb)
6449 by managing them correctly in the maintainer scripts (see
6450 <ref id=
"config-files">). This is important since we want
6451 to give the local system administrator the chance to adapt
6452 the scripts to the local system, e.g., to disable a
6453 service without de-installing the package, or to specify
6454 some special command line options when starting a service,
6455 while making sure their changes aren't lost during the next
6460 These scripts should not fail obscurely when the
6461 configuration files remain but the package has been
6462 removed, as configuration files remain on the system after
6463 the package has been removed. Only when
<prgn>dpkg
</prgn>
6464 is executed with the
<tt>--purge
</tt> option will
6465 configuration files be removed. In particular, as the
6466 <file>/etc/init.d/
<var>package
</var></file> script itself is
6467 usually a
<tt>conffile
</tt>, it will remain on the system
6468 if the package is removed but not purged. Therefore, you
6469 should include a
<tt>test
</tt> statement at the top of the
6471 <example compact=
"compact">
6472 test -f
<var>program-executed-later-in-script
</var> || exit
0
6477 Often there are some variables in the
<file>init.d
</file>
6478 scripts whose values control the behavior of the scripts,
6479 and which a system administrator is likely to want to
6480 change. As the scripts themselves are frequently
6481 <tt>conffile
</tt>s, modifying them requires that the
6482 administrator merge in their changes each time the package
6483 is upgraded and the
<tt>conffile
</tt> changes. To ease
6484 the burden on the system administrator, such configurable
6485 values should not be placed directly in the script.
6486 Instead, they should be placed in a file in
6487 <file>/etc/default
</file>, which typically will have the same
6488 base name as the
<file>init.d
</file> script. This extra file
6489 should be sourced by the script when the script runs. It
6490 must contain only variable settings and comments in SUSv3
6491 <prgn>sh
</prgn> format. It may either be a
6492 <tt>conffile
</tt> or a configuration file maintained by
6493 the package maintainer scripts. See
<ref id=
"config-files">
6498 To ensure that vital configurable values are always
6499 available, the
<file>init.d
</file> script should set default
6500 values for each of the shell variables it uses, either
6501 before sourcing the
<file>/etc/default/
</file> file or
6502 afterwards using something like the
<tt>:
6503 ${VAR:=default}
</tt> syntax. Also, the
<file>init.d
</file>
6504 script must behave sensibly and not fail if the
6505 <file>/etc/default
</file> file is deleted.
6509 <file>/var/run
</file> and
<file>/var/lock
</file> may be mounted
6510 as temporary filesystems
<footnote>
6511 For example, using the
<tt>RAMRUN
</tt> and
<tt>RAMLOCK
</tt>
6512 options in
<file>/etc/default/rcS
</file>.
6513 </footnote>, so the
<file>init.d
</file> scripts must handle this
6514 correctly. This will typically amount to creating any required
6515 subdirectories dynamically when the
<file>init.d
</file> script
6516 is run, rather than including them in the package and relying on
6517 <prgn>dpkg
</prgn> to create them.
6522 <heading>Interfacing with the initscript system
</heading>
6525 Maintainers should use the abstraction layer provided by
6526 the
<prgn>update-rc.d
</prgn> and
<prgn>invoke-rc.d
</prgn>
6527 programs to deal with initscripts in their packages'
6528 scripts such as
<prgn>postinst
</prgn>,
<prgn>prerm
</prgn>
6529 and
<prgn>postrm
</prgn>.
6533 Directly managing the /etc/rc?.d links and directly
6534 invoking the
<file>/etc/init.d/
</file> initscripts should
6535 be done only by packages providing the initscript
6536 subsystem (such as
<prgn>sysv-rc
</prgn> and
6537 <prgn>file-rc
</prgn>).
6541 <heading>Managing the links
</heading>
6544 The program
<prgn>update-rc.d
</prgn> is provided for
6545 package maintainers to arrange for the proper creation and
6546 removal of
<file>/etc/rc
<var>n
</var>.d
</file> symbolic links,
6547 or their functional equivalent if another method is being
6548 used. This may be used by maintainers in their packages'
6549 <prgn>postinst
</prgn> and
<prgn>postrm
</prgn> scripts.
6553 You must not include any
<file>/etc/rc
<var>n
</var>.d
</file>
6554 symbolic links in the actual archive or manually create or
6555 remove the symbolic links in maintainer scripts; you must
6556 use the
<prgn>update-rc.d
</prgn> program instead. (The
6557 former will fail if an alternative method of maintaining
6558 runlevel information is being used.) You must not include
6559 the
<file>/etc/rc
<var>n
</var>.d
</file> directories themselves
6560 in the archive either. (Only the
<tt>sysvinit
</tt>
6565 By default
<prgn>update-rc.d
</prgn> will start services in
6566 each of the multi-user state runlevels (
2,
3,
4, and
5)
6567 and stop them in the halt runlevel (
0), the single-user
6568 runlevel (
1) and the reboot runlevel (
6). The system
6569 administrator will have the opportunity to customize
6570 runlevels by simply adding, moving, or removing the
6571 symbolic links in
<file>/etc/rc
<var>n
</var>.d
</file> if
6572 symbolic links are being used, or by modifying
6573 <file>/etc/runlevel.conf
</file> if the
<tt>file-rc
</tt> method
6578 To get the default behavior for your package, put in your
6579 <prgn>postinst
</prgn> script
6580 <example compact=
"compact">
6581 update-rc.d
<var>package
</var> defaults
6583 and in your
<prgn>postrm
</prgn>
6584 <example compact=
"compact">
6585 if [
"$1" = purge ]; then
6586 update-rc.d
<var>package
</var> remove
6588 </example>. Note that if your package changes runlevels
6589 or priority, you may have to remove and recreate the links,
6590 since otherwise the old links may persist. Refer to the
6591 documentation of
<prgn>update-rc.d
</prgn>.
6595 This will use a default sequence number of
20. If it does
6596 not matter when or in which order the
<file>init.d
</file>
6597 script is run, use this default. If it does, then you
6598 should talk to the maintainer of the
<prgn>sysvinit
</prgn>
6599 package or post to
<tt>debian-devel
</tt>, and they will
6600 help you choose a number.
6604 For more information about using
<tt>update-rc.d
</tt>,
6605 please consult its man page
<manref name=
"update-rc.d"
6611 <heading>Running initscripts
</heading>
6613 The program
<prgn>invoke-rc.d
</prgn> is provided to make
6614 it easier for package maintainers to properly invoke an
6615 initscript, obeying runlevel and other locally-defined
6616 constraints that might limit a package's right to start,
6617 stop and otherwise manage services. This program may be
6618 used by maintainers in their packages' scripts.
6622 The package maintainer scripts must use
6623 <prgn>invoke-rc.d
</prgn> to invoke the
6624 <file>/etc/init.d/*
</file> initscripts, instead of
6625 calling them directly.
6629 By default,
<prgn>invoke-rc.d
</prgn> will pass any
6630 action requests (start, stop, reload, restart...) to the
6631 <file>/etc/init.d
</file> script, filtering out requests
6632 to start or restart a service out of its intended
6637 Most packages will simply need to change:
6638 <example compact=
"compact">/etc/init.d/
<package
>
6639 <action
></example> in their
<prgn>postinst
</prgn>
6640 and
<prgn>prerm
</prgn> scripts to:
6641 <example compact=
"compact">
6642 if which invoke-rc.d
>/dev/null
2>&1; then
6643 invoke-rc.d
<var>package
</var> <action
>
6645 /etc/init.d/
<var>package
</var> <action
>
6651 A package should register its initscript services using
6652 <prgn>update-rc.d
</prgn> before it tries to invoke them
6653 using
<prgn>invoke-rc.d
</prgn>. Invocation of
6654 unregistered services may fail.
6658 For more information about using
6659 <prgn>invoke-rc.d
</prgn>, please consult its man page
6660 <manref name=
"invoke-rc.d" section=
"8">.
6666 <heading>Boot-time initialization
</heading>
6669 There used to be another directory,
<file>/etc/rc.boot
</file>,
6670 which contained scripts which were run once per machine
6671 boot. This has been deprecated in favour of links from
6672 <file>/etc/rcS.d
</file> to files in
<file>/etc/init.d
</file> as
6673 described in
<ref id=
"/etc/init.d">. Packages must not
6674 place files in
<file>/etc/rc.boot
</file>.
6679 <heading>Example
</heading>
6682 An example on which you can base your
6683 <file>/etc/init.d
</file> scripts is found in
6684 <file>/etc/init.d/skeleton
</file>.
6691 <heading>Console messages from
<file>init.d
</file> scripts
</heading>
6694 This section describes the formats to be used for messages
6695 written to standard output by the
<file>/etc/init.d
</file>
6696 scripts. The intent is to improve the consistency of
6697 Debian's startup and shutdown look and feel. For this
6698 reason, please look very carefully at the details. We want
6699 the messages to have the same format in terms of wording,
6700 spaces, punctuation and case of letters.
6704 Here is a list of overall rules that should be used for
6705 messages generated by
<file>/etc/init.d
</file> scripts.
6711 The message should fit in one line (fewer than
80
6712 characters), start with a capital letter and end with
6713 a period (
<tt>.
</tt>) and line feed (
<tt>"\n"</tt>).
6717 If the script is performing some time consuming task in
6718 the background (not merely starting or stopping a
6719 program, for instance), an ellipsis (three dots:
6720 <tt>...
</tt>) should be output to the screen, with no
6721 leading or tailing whitespace or line feeds.
6725 The messages should appear as if the computer is telling
6726 the user what it is doing (politely :-), but should not
6727 mention
"it" directly. For example, instead of:
6728 <example compact=
"compact">
6729 I'm starting network daemons: nfsd mountd.
6731 the message should say
6732 <example compact=
"compact">
6733 Starting network daemons: nfsd mountd.
6740 <tt>init.d
</tt> script should use the following standard
6741 message formats for the situations enumerated below.
6747 <p>When daemons are started
</p>
6750 If the script starts one or more daemons, the output
6751 should look like this (a single line, no leading
6753 <example compact=
"compact">
6754 Starting
<var>description
</var>:
<var>daemon-
1</var> ...
<var>daemon-n
</var>.
6756 The
<var>description
</var> should describe the
6757 subsystem the daemon or set of daemons are part of,
6758 while
<var>daemon-
1</var> up to
<var>daemon-n
</var>
6759 denote each daemon's name (typically the file name of
6764 For example, the output of
<file>/etc/init.d/lpd
</file>
6766 <example compact=
"compact">
6767 Starting printer spooler: lpd.
6772 This can be achieved by saying
6773 <example compact=
"compact">
6774 echo -n
"Starting printer spooler: lpd"
6775 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6778 in the script. If there are more than one daemon to
6779 start, the output should look like this:
6780 <example compact=
"compact">
6781 echo -n
"Starting remote file system services:"
6782 echo -n
" nfsd"; start-stop-daemon --start --quiet nfsd
6783 echo -n
" mountd"; start-stop-daemon --start --quiet mountd
6784 echo -n
" ugidd"; start-stop-daemon --start --quiet ugidd
6787 This makes it possible for the user to see what is
6788 happening and when the final daemon has been started.
6789 Care should be taken in the placement of white spaces:
6790 in the example above the system administrators can
6791 easily comment out a line if they don't want to start
6792 a specific daemon, while the displayed message still
6798 <p>When a system parameter is being set
</p>
6801 If you have to set up different system parameters
6802 during the system boot, you should use this format:
6803 <example compact=
"compact">
6804 Setting
<var>parameter
</var> to
"<var>value</var>".
6809 You can use a statement such as the following to get
6811 <example compact=
"compact">
6812 echo
"Setting DNS domainname to \"$domainname\
"."
6817 Note that the same symbol (
<tt>"</tt>) <!-- " --> is used
6818 for the left and right quotation marks. A grave accent
6819 (
<tt>`
</tt>) is not a quote character; neither is an
6820 apostrophe (
<tt>'
</tt>).
6825 <p>When a daemon is stopped or restarted
</p>
6828 When you stop or restart a daemon, you should issue a
6829 message identical to the startup message, except that
6830 <tt>Starting
</tt> is replaced with
<tt>Stopping
</tt>
6831 or
<tt>Restarting
</tt> respectively.
6835 For example, stopping the printer daemon will look like
6837 <example compact=
"compact">
6838 Stopping printer spooler: lpd.
6844 <p>When something is executed
</p>
6847 There are several examples where you have to run a
6848 program at system startup or shutdown to perform a
6849 specific task, for example, setting the system's clock
6850 using
<prgn>netdate
</prgn> or killing all processes
6851 when the system shuts down. Your message should look
6853 <example compact=
"compact">
6854 Doing something very useful...done.
6856 You should print the
<tt>done.
</tt> immediately after
6857 the job has been completed, so that the user is
6858 informed why they have to wait. You can get this
6860 <example compact=
"compact">
6861 echo -n
"Doing something very useful..."
6870 <p>When the configuration is reloaded
</p>
6873 When a daemon is forced to reload its configuration
6874 files you should use the following format:
6875 <example compact=
"compact">
6876 Reloading
<var>description
</var> configuration...done.
6878 where
<var>description
</var> is the same as in the
6879 daemon starting message.
6887 <heading>Cron jobs
</heading>
6890 Packages must not modify the configuration file
6891 <file>/etc/crontab
</file>, and they must not modify the files in
6892 <file>/var/spool/cron/crontabs
</file>.
</p>
6895 If a package wants to install a job that has to be executed
6896 via cron, it should place a file with the name of the
6897 package in one or more of the following directories:
6898 <example compact=
"compact">
6904 As these directory names imply, the files within them are
6905 executed on an hourly, daily, weekly, or monthly basis,
6906 respectively. The exact times are listed in
6907 <file>/etc/crontab
</file>.
</p>
6910 All files installed in any of these directories must be
6911 scripts (e.g., shell scripts or Perl scripts) so that they
6912 can easily be modified by the local system administrator.
6913 In addition, they must be treated as configuration files.
6917 If a certain job has to be executed at some other frequency or
6918 at a specific time, the package should install a file
6919 <file>/etc/cron.d/
<var>package
</var></file>. This file uses the
6920 same syntax as
<file>/etc/crontab
</file> and is processed by
6921 <prgn>cron
</prgn> automatically. The file must also be
6922 treated as a configuration file. (Note that entries in the
6923 <file>/etc/cron.d
</file> directory are not handled by
6924 <prgn>anacron
</prgn>. Thus, you should only use this
6925 directory for jobs which may be skipped if the system is not
6928 Unlike
<file>crontab
</file> files described in the IEEE Std
6929 1003.1-
2008 (POSIX
.1) available from
6930 <url id=
"http://www.opengroup.org/onlinepubs/9699919799/"
6931 name=
"The Open Group">, the files in
6932 <file>/etc/cron.d
</file> and the file
6933 <file>/etc/crontab
</file> have seven fields; namely:
6935 <item>Minute [
0,
59]
</item>
6936 <item>Hour [
0,
23]
</item>
6937 <item>Day of the month [
1,
31]
</item>
6938 <item>Month of the year [
1,
12]
</item>
6939 <item>Day of the week ([
0,
6] with
0=Sunday)
</item>
6940 <item>Username
</item>
6941 <item>Command to be run
</item>
6943 Ranges of numbers are allowed. Ranges are two numbers
6944 separated with a hyphen. The specified range is inclusive.
6945 Lists are allowed. A list is a set of numbers (or ranges)
6946 separated by commas. Step values can be used in conjunction
6951 The scripts or
<tt>crontab
</tt> entries in these directories should
6952 check if all necessary programs are installed before they
6953 try to execute them. Otherwise, problems will arise when a
6954 package was removed but not purged since configuration files
6955 are kept on the system in this situation.
6959 Any
<tt>cron
</tt> daemon must provide
6960 <file>/usr/bin/crontab
</file> and support normal
6961 <tt>crontab
</tt> entries as specified in POSIX. The daemon
6962 must also support names for days and months, ranges, and
6963 step values. It has to support
<file>/etc/crontab
</file>,
6964 and correctly execute the scripts in
6965 <file>/etc/cron.d
</file>. The daemon must also correctly
6967 <file>/etc/cron.{hourly,daily,weekly,monthly}
</file>.
6972 <heading>Menus
</heading>
6975 The Debian
<tt>menu
</tt> package provides a standard
6976 interface between packages providing applications and
6977 <em>menu programs
</em> (either X window managers or
6978 text-based menu programs such as
<prgn>pdmenu
</prgn>).
6982 All packages that provide applications that need not be
6983 passed any special command line arguments for normal
6984 operation should register a menu entry for those
6985 applications, so that users of the
<tt>menu
</tt> package
6986 will automatically get menu entries in their window
6987 managers, as well in shells like
<tt>pdmenu
</tt>.
6991 Menu entries should follow the current menu policy.
6995 The menu policy can be found in the
<tt>menu-policy
</tt>
6996 files in the
<tt>debian-policy
</tt> package.
6997 It is also available from the Debian web mirrors at
6998 <tt><url name=
"/doc/packaging-manuals/menu-policy/"
6999 id=
"http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
7003 Please also refer to the
<em>Debian Menu System
</em>
7004 documentation that comes with the
<package>menu
</package>
7005 package for information about how to register your
7011 <heading>Multimedia handlers
</heading>
7014 MIME (Multipurpose Internet Mail Extensions, RFCs
2045-
2049)
7015 is a mechanism for encoding files and data streams and
7016 providing meta-information about them, in particular their
7017 type (e.g. audio or video) and format (e.g. PNG, HTML,
7022 Registration of MIME type handlers allows programs like mail
7023 user agents and web browsers to invoke these handlers to
7024 view, edit or display MIME types they don't support directly.
7028 Packages which provide the ability to view/show/play,
7029 compose, edit or print MIME types should register themselves
7030 as such following the current MIME support policy.
7034 The MIME support policy can be found in the
<tt>mime-policy
</tt>
7035 files in the
<tt>debian-policy
</tt> package.
7036 It is also available from the Debian web mirrors at
7037 <tt><url name=
"/doc/packaging-manuals/mime-policy/"
7038 id=
"http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
7044 <heading>Keyboard configuration
</heading>
7047 To achieve a consistent keyboard configuration so that all
7048 applications interpret a keyboard event the same way, all
7049 programs in the Debian distribution must be configured to
7050 comply with the following guidelines.
7054 The following keys must have the specified interpretations:
7057 <tag><tt><--
</tt></tag>
7058 <item>delete the character to the left of the cursor
</item>
7060 <tag><tt>Delete
</tt></tag>
7061 <item>delete the character to the right of the cursor
</item>
7063 <tag><tt>Control+H
</tt></tag>
7064 <item>emacs: the help prefix
</item>
7067 The interpretation of any keyboard events should be
7068 independent of the terminal that is used, be it a virtual
7069 console, an X terminal emulator, an rlogin/telnet session,
7074 The following list explains how the different programs
7075 should be set up to achieve this:
7081 <tt><--
</tt> generates
<tt>KB_BackSpace
</tt> in X.
7085 <tt>Delete
</tt> generates
<tt>KB_Delete
</tt> in X.
7089 X translations are set up to make
7090 <tt>KB_Backspace
</tt> generate ASCII DEL, and to make
7091 <tt>KB_Delete
</tt> generate
<tt>ESC [
3 ~
</tt> (this
7092 is the vt220 escape code for the
"delete character"
7093 key). This must be done by loading the X resources
7094 using
<prgn>xrdb
</prgn> on all local X displays, not
7095 using the application defaults, so that the
7096 translation resources used correspond to the
7097 <prgn>xmodmap
</prgn> settings.
7101 The Linux console is configured to make
7102 <tt><--
</tt> generate DEL, and
<tt>Delete
</tt>
7103 generate
<tt>ESC [
3 ~
</tt>.
7107 X applications are configured so that
<tt><</tt>
7108 deletes left, and
<tt>Delete
</tt> deletes right. Motif
7109 applications already work like this.
7113 Terminals should have
<tt>stty erase ^?
</tt> .
7117 The
<tt>xterm
</tt> terminfo entry should have
<tt>ESC
7118 [
3 ~
</tt> for
<tt>kdch1
</tt>, just as for
7119 <tt>TERM=linux
</tt> and
<tt>TERM=vt220
</tt>.
7123 Emacs is programmed to map
<tt>KB_Backspace
</tt> or
7124 the
<tt>stty erase
</tt> character to
7125 <tt>delete-backward-char
</tt>, and
<tt>KB_Delete
</tt>
7126 or
<tt>kdch1
</tt> to
<tt>delete-forward-char
</tt>, and
7127 <tt>^H
</tt> to
<tt>help
</tt> as always.
7131 Other applications use the
<tt>stty erase
</tt>
7132 character and
<tt>kdch1
</tt> for the two delete keys,
7133 with ASCII DEL being
"delete previous character" and
7134 <tt>kdch1
</tt> being
"delete character under
7142 This will solve the problem except for the following
7149 Some terminals have a
<tt><--
</tt> key that cannot
7150 be made to produce anything except
<tt>^H
</tt>. On
7151 these terminals Emacs help will be unavailable on
7152 <tt>^H
</tt> (assuming that the
<tt>stty erase
</tt>
7153 character takes precedence in Emacs, and has been set
7154 correctly).
<tt>M-x help
</tt> or
<tt>F1
</tt> (if
7155 available) can be used instead.
7159 Some operating systems use
<tt>^H
</tt> for
<tt>stty
7160 erase
</tt>. However, modern telnet versions and all
7161 rlogin versions propagate
<tt>stty
</tt> settings, and
7162 almost all UNIX versions honour
<tt>stty erase
</tt>.
7163 Where the
<tt>stty
</tt> settings are not propagated
7164 correctly, things can be made to work by using
7165 <tt>stty
</tt> manually.
7169 Some systems (including previous Debian versions) use
7170 <prgn>xmodmap
</prgn> to arrange for both
7171 <tt><--
</tt> and
<tt>Delete
</tt> to generate
7172 <tt>KB_Delete
</tt>. We can change the behavior of
7173 their X clients using the same X resources that we use
7174 to do it for our own clients, or configure our clients
7175 using their resources when things are the other way
7176 around. On displays configured like this
7177 <tt>Delete
</tt> will not work, but
<tt><--
</tt>
7182 Some operating systems have different
<tt>kdch1
</tt>
7183 settings in their
<tt>terminfo
</tt> database for
7184 <tt>xterm
</tt> and others. On these systems the
7185 <tt>Delete
</tt> key will not work correctly when you
7186 log in from a system conforming to our policy, but
7187 <tt><--
</tt> will.
7194 <heading>Environment variables
</heading>
7197 A program must not depend on environment variables to get
7198 reasonable defaults. (That's because these environment
7199 variables would have to be set in a system-wide
7200 configuration file like
<file>/etc/profile
</file>, which is not
7201 supported by all shells.)
7205 If a program usually depends on environment variables for its
7206 configuration, the program should be changed to fall back to
7207 a reasonable default configuration if these environment
7208 variables are not present. If this cannot be done easily
7209 (e.g., if the source code of a non-free program is not
7210 available), the program must be replaced by a small
7211 "wrapper" shell script which sets the environment variables
7212 if they are not already defined, and calls the original program.
7216 Here is an example of a wrapper script for this purpose:
7218 <example compact=
"compact">
7220 BAR=${BAR:-/var/lib/fubar}
7222 exec /usr/lib/foo/foo
"$@"
7227 Furthermore, as
<file>/etc/profile
</file> is a configuration
7228 file of the
<prgn>base-files
</prgn> package, other packages must
7229 not put any environment variables or other commands into that
7234 <sect id=
"doc-base">
7235 <heading>Registering Documents using doc-base
</heading>
7238 The
<package>doc-base
</package> package implements a
7239 flexible mechanism for handling and presenting
7240 documentation. The recommended practice is for every Debian
7241 package that provides online documentation (other than just
7242 manual pages) to register these documents with
7243 <package>doc-base
</package> by installing a
7244 <package>doc-base
</package> control file via the
7245 <prgn/install-docs/ script at installation time and
7246 de-register the manuals again when the package is removed.
7249 Please refer to the documentation that comes with the
7250 <package>doc-base
</package> package for information and
7259 <heading>Files
</heading>
7261 <sect id=
"binaries">
7262 <heading>Binaries
</heading>
7265 Two different packages must not install programs with
7266 different functionality but with the same filenames. (The
7267 case of two programs having the same functionality but
7268 different implementations is handled via
"alternatives" or
7269 the
"Conflicts" mechanism. See
<ref id=
"maintscripts"> and
7270 <ref id=
"conflicts"> respectively.) If this case happens,
7271 one of the programs must be renamed. The maintainers should
7272 report this to the
<tt>debian-devel
</tt> mailing list and
7273 try to find a consensus about which program will have to be
7274 renamed. If a consensus cannot be reached,
<em>both
</em>
7275 programs must be renamed.
7279 By default, when a package is being built, any binaries
7280 created should include debugging information, as well as
7281 being compiled with optimization. You should also turn on
7282 as many reasonable compilation warnings as possible; this
7283 makes life easier for porters, who can then look at build
7284 logs for possible problems. For the C programming language,
7285 this means the following compilation parameters should be
7287 <example compact=
"compact">
7289 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7291 INSTALL = install -s # (or use strip on the files in debian/tmp)
7296 Note that by default all installed binaries should be stripped,
7297 either by using the
<tt>-s
</tt> flag to
7298 <prgn>install
</prgn>, or by calling
<prgn>strip
</prgn> on
7299 the binaries after they have been copied into
7300 <file>debian/tmp
</file> but before the tree is made into a
7305 Although binaries in the build tree should be compiled with
7306 debugging information by default, it can often be difficult to
7307 debug programs if they are also subjected to compiler
7308 optimization. For this reason, it is recommended to support the
7309 standardized environment variable
<tt>DEB_BUILD_OPTIONS
</tt>
7310 (see
<ref id=
"debianrules-options">). This variable can contain
7311 several flags to change how a package is compiled and built.
7315 It is up to the package maintainer to decide what
7316 compilation options are best for the package. Certain
7317 binaries (such as computationally-intensive programs) will
7318 function better with certain flags (
<tt>-O3
</tt>, for
7319 example); feel free to use them. Please use good judgment
7320 here. Don't use flags for the sake of it; only use them
7321 if there is good reason to do so. Feel free to override
7322 the upstream author's ideas about which compilation
7323 options are best: they are often inappropriate for our
7329 <sect id=
"libraries">
7330 <heading>Libraries
</heading>
7333 If the package is
<strong>architecture: any
</strong>, then
7334 the shared library compilation and linking flags must have
7335 <tt>-fPIC
</tt>, or the package shall not build on some of
7336 the supported architectures
<footnote>
7338 If you are using GCC,
<tt>-fPIC
</tt> produces code with
7339 relocatable position independent code, which is required for
7340 most architectures to create a shared library, with i386 and
7341 perhaps some others where non position independent code is
7342 permitted in a shared library.
7345 Position independent code may have a performance penalty,
7346 especially on
<tt>i386
</tt>. However, in most cases the
7347 speed penalty must be measured against the memory wasted on
7348 the few architectures where non position independent code is
7351 </footnote>. Any exception to this rule must be discussed on
7352 the mailing list
<em>debian-devel@lists.debian.org
</em>, and
7353 a rough consensus obtained. The reasons for not compiling
7354 with
<tt>-fPIC
</tt> flag must be recorded in the file
7355 <tt>README.Debian
</tt>, and care must be taken to either
7356 restrict the architecture or arrange for
<tt>-fPIC
</tt> to
7357 be used on architectures where it is required.
<footnote>
7359 Some of the reasons why this might be required is if the
7360 library contains hand crafted assembly code that is not
7361 relocatable, the speed penalty is excessive for compute
7362 intensive libs, and similar reasons.
7367 As to the static libraries, the common case is not to have
7368 relocatable code, since there is no benefit, unless in specific
7369 cases; therefore the static version must not be compiled
7370 with the
<tt>-fPIC
</tt> flag. Any exception to this rule
7371 should be discussed on the mailing list
7372 <em>debian-devel@lists.debian.org
</em>, and the reasons for
7373 compiling with the
<tt>-fPIC
</tt> flag must be recorded in
7374 the file
<tt>README.Debian
</tt>.
<footnote>
7376 Some of the reasons for linking static libraries with
7377 the
<tt>-fPIC
</tt> flag are if, for example, one needs a
7378 Perl API for a library that is under rapid development,
7379 and has an unstable API, so shared libraries are
7380 pointless at this phase of the library's development. In
7381 that case, since Perl needs a library with relocatable
7382 code, it may make sense to create a static library with
7383 relocatable code. Another reason cited is if you are
7384 distilling various libraries into a common shared
7385 library, like
<tt>mklibs
</tt> does in the Debian
7391 In other words, if both a shared and a static library is
7392 being built, each source unit (
<tt>*.c
</tt>, for example,
7393 for C files) will need to be compiled twice, for the normal
7398 Libraries should be built with threading support and to be
7399 thread-safe if the library supports this.
7403 Although not enforced by the build tools, shared libraries
7404 must be linked against all libraries that they use symbols from
7405 in the same way that binaries are. This ensures the correct
7406 functioning of the
<qref id=
"sharedlibs-shlibdeps">shlibs
</qref>
7407 system and guarantees that all libraries can be safely opened
7408 with
<tt>dlopen()
</tt>. Packagers may wish to use the gcc
7409 option
<tt>-Wl,-z,defs
</tt> when building a shared library.
7410 Since this option enforces symbol resolution at build time,
7411 a missing library reference will be caught early as a fatal
7416 All installed shared libraries should be stripped with
7417 <example compact=
"compact">
7418 strip --strip-unneeded
<var>your-lib
</var>
7420 (The option
<tt>--strip-unneeded
</tt> makes
7421 <prgn>strip
</prgn> remove only the symbols which aren't
7422 needed for relocation processing.) Shared libraries can
7423 function perfectly well when stripped, since the symbols for
7424 dynamic linking are in a separate part of the ELF object
7426 You might also want to use the options
7427 <tt>--remove-section=.comment
</tt> and
7428 <tt>--remove-section=.note
</tt> on both shared libraries
7429 and executables, and
<tt>--strip-debug
</tt> on static
7435 Note that under some circumstances it may be useful to
7436 install a shared library unstripped, for example when
7437 building a separate package to support debugging.
7441 Shared object files (often
<file>.so
</file> files) that are not
7442 public libraries, that is, they are not meant to be linked
7443 to by third party executables (binaries of other packages),
7444 should be installed in subdirectories of the
7445 <file>/usr/lib
</file> directory. Such files are exempt from the
7446 rules that govern ordinary shared libraries, except that
7447 they must not be installed executable and should be
7449 A common example are the so-called
"plug-ins",
7450 internal shared objects that are dynamically loaded by
7451 programs using
<manref name=
"dlopen" section=
"3">.
7456 Packages that use
<prgn>libtool
</prgn> to create and install
7457 their shared libraries install a file containing additional
7458 metadata (ending in
<file>.la
</file>) alongside the library.
7459 For public libraries intended for use by other packages, these
7460 files normally should not be included in the Debian package,
7461 since the information they include is not necessary to link with
7462 the shared library on Debian and can add unnecessary additional
7463 dependencies to other programs or libraries.
<footnote>
7464 These files store, among other things, all libraries on which
7465 that shared library depends. Unfortunately, if
7466 the
<file>.la
</file> file is present and contains that
7467 dependency information, using
<prgn>libtool
</prgn> when
7468 linking against that library will cause the resulting program
7469 or library to be linked against those dependencies as well,
7470 even if this is unnecessary. This can create unneeded
7471 dependencies on shared library packages that would otherwise
7472 be hidden behind the library ABI, and can make library
7473 transitions to new SONAMEs unnecessarily complicated and
7474 difficult to manage.
7476 If the
<file>.la
</file> file is required for that library (if,
7477 for instance, it's loaded via
<tt>libltdl
</tt> in a way that
7478 requires that meta-information), the
<tt>dependency_libs
</tt>
7479 setting in the
<file>.la
</file> file should normally be set to
7480 the empty string. If the shared library development package has
7481 historically included the
<file>.la
</file>, it must be retained
7482 in the development package (with
<tt>dependency_libs
</tt>
7483 emptied) until all libraries that depend on it have removed or
7484 emptied
<tt>dependency_libs
</tt> in their
<file>.la
</file>
7485 files to prevent linking with those other libraries
7486 using
<prgn>libtool
</prgn> from failing.
7490 If the
<file>.la
</file> must be included, it should be included
7491 in the development (
<tt>-dev
</tt>) package, unless the library
7492 will be loaded by
<prgn>libtool
</prgn>'s
<tt>libltdl
</tt>
7493 library. If it is intended for use with
<tt>libltdl
</tt>,
7494 the
<file>.la
</file> files must go in the run-time library
7499 These requirements for handling of
<file>.la
</file> files do not
7500 apply to loadable modules or libraries not installed in
7501 directories searched by default by the dynamic linker. Packages
7502 installing loadable modules will frequently need to install
7503 the
<file>.la
</file> files alongside the modules so that they
7504 can be loaded by
<tt>libltdl
</tt>.
<tt>dependency_libs
</tt>
7505 does not need to be modified for libraries or modules that are
7506 not installed in directories searched by the dynamic linker by
7507 default and not intended for use by other packages.
7511 You must make sure that you use only released versions of
7512 shared libraries to build your packages; otherwise other
7513 users will not be able to run your binaries
7514 properly. Producing source packages that depend on
7515 unreleased compilers is also usually a bad
7522 <heading>Shared libraries
</heading>
7524 This section has moved to
<ref id=
"sharedlibs">.
7530 <heading>Scripts
</heading>
7533 All command scripts, including the package maintainer
7534 scripts inside the package and used by
<prgn>dpkg
</prgn>,
7535 should have a
<tt>#!
</tt> line naming the shell to be used
7540 In the case of Perl scripts this should be
7541 <tt>#!/usr/bin/perl
</tt>.
7545 When scripts are installed into a directory in the system
7546 PATH, the script name should not include an extension such
7547 as
<tt>.sh
</tt> or
<tt>.pl
</tt> that denotes the scripting
7548 language currently used to implement it.
7551 Shell scripts (
<prgn>sh
</prgn> and
<prgn>bash
</prgn>) other than
7552 <file>init.d
</file> scripts should almost certainly start
7553 with
<tt>set -e
</tt> so that errors are detected.
7554 <file>init.d
</file> scripts are something of a special case, due
7555 to how frequently they need to call commands that are allowed to
7556 fail, and it may instead be easier to check the exit status of
7557 commands directly. See
<ref id=
"writing-init"> for more
7558 information about writing
<file>init.d
</file> scripts.
7561 Every script should use
<tt>set -e
</tt> or check the exit status
7562 of
<em>every
</em> command.
7565 Scripts may assume that
<file>/bin/sh
</file> implements the
7566 SUSv3 Shell Command Language
<footnote>
7567 Single UNIX Specification, version
3, which is also IEEE
7568 1003.1-
2004 (POSIX), and is available on the World Wide Web
7569 from
<url id=
"http://www.unix.org/version3/online.html"
7570 name=
"The Open Group"> after free
7571 registration.
</footnote>
7572 plus the following additional features not mandated by
7574 These features are in widespread use in the Linux community
7575 and are implemented in all of bash, dash, and ksh, the most
7576 common shells users may wish to use as
<file>/bin/sh
</file>.
7579 <item><tt>echo -n
</tt>, if implemented as a shell built-in,
7580 must not generate a newline.
</item>
7581 <item><tt>test
</tt>, if implemented as a shell built-in, must
7582 support
<tt>-a
</tt> and
<tt>-o
</tt> as binary logical
7584 <item><tt>local
</tt> to create a scoped variable must be
7585 supported, including listing multiple variables in a single
7586 local command and assigning a value to a variable at the
7587 same time as localizing it.
<tt>local
</tt> may or
7588 may not preserve the variable value from an outer scope if
7589 no assignment is present. Uses such as:
7593 # ... use a, b, c, d ...
7596 must be supported and must set the value of
<tt>c
</tt> to
7600 If a shell script requires non-SUSv3 features from the shell
7601 interpreter other than those listed above, the appropriate shell
7602 must be specified in the first line of the script (e.g.,
7603 <tt>#!/bin/bash
</tt>) and the package must depend on the package
7604 providing the shell (unless the shell package is marked
7605 "Essential", as in the case of
<prgn>bash
</prgn>).
7609 You may wish to restrict your script to SUSv3 features plus the
7610 above set when possible so that it may use
<file>/bin/sh
</file>
7611 as its interpreter. If your script works with
<prgn>dash
</prgn>
7612 (originally called
<prgn>ash
</prgn>), it probably complies with
7613 the above requirements, but if you are in doubt, use
7614 <file>/bin/bash
</file>.
7618 Perl scripts should check for errors when making any
7619 system calls, including
<tt>open
</tt>,
<tt>print
</tt>,
7620 <tt>close
</tt>,
<tt>rename
</tt> and
<tt>system
</tt>.
7624 <prgn>csh
</prgn> and
<prgn>tcsh
</prgn> should be avoided as
7625 scripting languages. See
<em>Csh Programming Considered
7626 Harmful
</em>, one of the
<tt>comp.unix.*
</tt> FAQs, which
7627 can be found at
<url id=
"http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7628 If an upstream package comes with
<prgn>csh
</prgn> scripts
7629 then you must make sure that they start with
7630 <tt>#!/bin/csh
</tt> and make your package depend on the
7631 <prgn>c-shell
</prgn> virtual package.
7635 Any scripts which create files in world-writeable
7636 directories (e.g., in
<file>/tmp
</file>) must use a
7637 mechanism which will fail atomically if a file with the same
7638 name already exists.
7642 The Debian base system provides the
<prgn>tempfile
</prgn>
7643 and
<prgn>mktemp
</prgn> utilities for use by scripts for
7650 <heading>Symbolic links
</heading>
7653 In general, symbolic links within a top-level directory
7654 should be relative, and symbolic links pointing from one
7655 top-level directory into another should be absolute. (A
7656 top-level directory is a sub-directory of the root
7657 directory
<file>/
</file>.)
7661 In addition, symbolic links should be specified as short as
7662 possible, i.e., link targets like
<file>foo/../bar
</file> are
7667 Note that when creating a relative link using
7668 <prgn>ln
</prgn> it is not necessary for the target of the
7669 link to exist relative to the working directory you're
7670 running
<prgn>ln
</prgn> from, nor is it necessary to change
7671 directory to the directory where the link is to be made.
7672 Simply include the string that should appear as the target
7673 of the link (this will be a pathname relative to the
7674 directory in which the link resides) as the first argument
7679 For example, in your
<prgn>Makefile
</prgn> or
7680 <file>debian/rules
</file>, you can do things like:
7681 <example compact=
"compact">
7682 ln -fs gcc $(prefix)/bin/cc
7683 ln -fs gcc debian/tmp/usr/bin/cc
7684 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7685 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7690 A symbolic link pointing to a compressed file should always
7691 have the same file extension as the referenced file. (For
7692 example, if a file
<file>foo.gz
</file> is referenced by a
7693 symbolic link, the filename of the link has to end with
7694 "<file>.gz</file>" too, as in
<file>bar.gz
</file>.)
7699 <heading>Device files
</heading>
7702 Packages must not include device files or named pipes in the
7707 If a package needs any special device files that are not
7708 included in the base system, it must call
7709 <prgn>MAKEDEV
</prgn> in the
<prgn>postinst
</prgn> script,
7710 after notifying the user
<footnote>
7711 This notification could be done via a (low-priority)
7712 debconf message, or an echo (printf) statement.
7717 Packages must not remove any device files in the
7718 <prgn>postrm
</prgn> or any other script. This is left to the
7719 system administrator.
7723 Debian uses the serial devices
7724 <file>/dev/ttyS*
</file>. Programs using the old
7725 <file>/dev/cu*
</file> devices should be changed to use
7726 <file>/dev/ttyS*
</file>.
7730 Named pipes needed by the package must be created in
7731 the
<prgn>postinst
</prgn> script
<footnote>
7732 It's better to use
<prgn>mkfifo
</prgn> rather
7733 than
<prgn>mknod
</prgn> to create named pipes so that
7734 automated checks for packages incorrectly creating device
7735 files with
<prgn>mknod
</prgn> won't have false positives.
7736 </footnote> and removed in
7737 the
<prgn>prerm
</prgn> or
<prgn>postrm
</prgn> script as
7742 <sect id=
"config-files">
7743 <heading>Configuration files
</heading>
7746 <heading>Definitions
</heading>
7750 <tag>configuration file
</tag>
7752 A file that affects the operation of a program, or
7753 provides site- or host-specific information, or
7754 otherwise customizes the behavior of a program.
7755 Typically, configuration files are intended to be
7756 modified by the system administrator (if needed or
7757 desired) to conform to local policy or to provide
7758 more useful site-specific behavior.
7761 <tag><tt>conffile
</tt></tag>
7763 A file listed in a package's
<tt>conffiles
</tt>
7764 file, and is treated specially by
<prgn>dpkg
</prgn>
7765 (see
<ref id=
"configdetails">).
7771 The distinction between these two is important; they are
7772 not interchangeable concepts. Almost all
7773 <tt>conffile
</tt>s are configuration files, but many
7774 configuration files are not
<tt>conffiles
</tt>.
7778 As noted elsewhere,
<file>/etc/init.d
</file> scripts,
7779 <file>/etc/default
</file> files, scripts installed in
7780 <file>/etc/cron.{hourly,daily,weekly,monthly}
</file>, and cron
7781 configuration installed in
<file>/etc/cron.d
</file> must be
7782 treated as configuration files. In general, any script that
7783 embeds configuration information is de-facto a configuration
7784 file and should be treated as such.
7789 <heading>Location
</heading>
7792 Any configuration files created or used by your package
7793 must reside in
<file>/etc
</file>. If there are several,
7794 consider creating a subdirectory of
<file>/etc
</file>
7795 named after your package.
7799 If your package creates or uses configuration files
7800 outside of
<file>/etc
</file>, and it is not feasible to modify
7801 the package to use
<file>/etc
</file> directly, put the files
7802 in
<file>/etc
</file> and create symbolic links to those files
7803 from the location that the package requires.
7808 <heading>Behavior
</heading>
7811 Configuration file handling must conform to the following
7813 <list compact=
"compact">
7815 local changes must be preserved during a package
7819 configuration files must be preserved when the
7820 package is removed, and only deleted when the
7824 Obsolete configuration files without local changes may be
7825 removed by the package during upgrade.
7829 The easy way to achieve this behavior is to make the
7830 configuration file a
<tt>conffile
</tt>. This is
7831 appropriate only if it is possible to distribute a default
7832 version that will work for most installations, although
7833 some system administrators may choose to modify it. This
7834 implies that the default version will be part of the
7835 package distribution, and must not be modified by the
7836 maintainer scripts during installation (or at any other
7841 In order to ensure that local changes are preserved
7842 correctly, no package may contain or make hard links to
7843 conffiles.
<footnote>
7844 Rationale: There are two problems with hard links.
7845 The first is that some editors break the link while
7846 editing one of the files, so that the two files may
7847 unwittingly become unlinked and different. The second
7848 is that
<prgn>dpkg
</prgn> might break the hard link
7849 while upgrading
<tt>conffile
</tt>s.
7854 The other way to do it is via the maintainer scripts. In
7855 this case, the configuration file must not be listed as a
7856 <tt>conffile
</tt> and must not be part of the package
7857 distribution. If the existence of a file is required for
7858 the package to be sensibly configured it is the
7859 responsibility of the package maintainer to provide
7860 maintainer scripts which correctly create, update and
7861 maintain the file and remove it on purge. (See
<ref
7862 id=
"maintainerscripts"> for more information.) These
7863 scripts must be idempotent (i.e., must work correctly if
7864 <prgn>dpkg
</prgn> needs to re-run them due to errors
7865 during installation or removal), must cope with all the
7866 variety of ways
<prgn>dpkg
</prgn> can call maintainer
7867 scripts, must not overwrite or otherwise mangle the user's
7868 configuration without asking, must not ask unnecessary
7869 questions (particularly during upgrades), and must
7870 otherwise be good citizens.
7874 The scripts are not required to configure every possible
7875 option for the package, but only those necessary to get
7876 the package running on a given system. Ideally the
7877 sysadmin should not have to do any configuration other
7878 than that done (semi-)automatically by the
7879 <prgn>postinst
</prgn> script.
7883 A common practice is to create a script called
7884 <file><var>package
</var>-configure
</file> and have the
7885 package's
<prgn>postinst
</prgn> call it if and only if the
7886 configuration file does not already exist. In certain
7887 cases it is useful for there to be an example or template
7888 file which the maintainer scripts use. Such files should
7889 be in
<file>/usr/share/
<var>package
</var></file> or
7890 <file>/usr/lib/
<var>package
</var></file> (depending on whether
7891 they are architecture-independent or not). There should
7892 be symbolic links to them from
7893 <file>/usr/share/doc/
<var>package
</var>/examples
</file> if
7894 they are examples, and should be perfectly ordinary
7895 <prgn>dpkg
</prgn>-handled files (
<em>not
</em>
7896 configuration files).
7900 These two styles of configuration file handling must
7901 not be mixed, for that way lies madness:
7902 <prgn>dpkg
</prgn> will ask about overwriting the file
7903 every time the package is upgraded.
7908 <heading>Sharing configuration files
</heading>
7911 Packages which specify the same file as a
7912 <tt>conffile
</tt> must be tagged as
<em>conflicting
</em>
7913 with each other. (This is an instance of the general rule
7914 about not sharing files. Note that neither alternatives
7915 nor diversions are likely to be appropriate in this case;
7916 in particular,
<prgn>dpkg
</prgn> does not handle diverted
7917 <tt>conffile
</tt>s well.)
7921 The maintainer scripts must not alter a
<tt>conffile
</tt>
7922 of
<em>any
</em> package, including the one the scripts
7927 If two or more packages use the same configuration file
7928 and it is reasonable for both to be installed at the same
7929 time, one of these packages must be defined as
7930 <em>owner
</em> of the configuration file, i.e., it will be
7931 the package which handles that file as a configuration
7932 file. Other packages that use the configuration file must
7933 depend on the owning package if they require the
7934 configuration file to operate. If the other package will
7935 use the configuration file if present, but is capable of
7936 operating without it, no dependency need be declared.
7940 If it is desirable for two or more related packages to
7941 share a configuration file
<em>and
</em> for all of the
7942 related packages to be able to modify that configuration
7943 file, then the following should be done:
7944 <enumlist compact=
"compact">
7946 One of the related packages (the
"owning" package)
7947 will manage the configuration file with maintainer
7948 scripts as described in the previous section.
7951 The owning package should also provide a program
7952 that the other packages may use to modify the
7956 The related packages must use the provided program
7957 to make any desired modifications to the
7958 configuration file. They should either depend on
7959 the core package to guarantee that the configuration
7960 modifier program is available or accept gracefully
7961 that they cannot modify the configuration file if it
7962 is not. (This is in addition to the fact that the
7963 configuration file may not even be present in the
7970 Sometimes it's appropriate to create a new package which
7971 provides the basic infrastructure for the other packages
7972 and which manages the shared configuration files. (The
7973 <tt>sgml-base
</tt> package is a good example.)
7978 <heading>User configuration files (
"dotfiles")
</heading>
7981 The files in
<file>/etc/skel
</file> will automatically be
7982 copied into new user accounts by
<prgn>adduser
</prgn>.
7983 No other program should reference the files in
7984 <file>/etc/skel
</file>.
7988 Therefore, if a program needs a dotfile to exist in
7989 advance in
<file>$HOME
</file> to work sensibly, that dotfile
7990 should be installed in
<file>/etc/skel
</file> and treated as a
7995 However, programs that require dotfiles in order to
7996 operate sensibly are a bad thing, unless they do create
7997 the dotfiles themselves automatically.
8001 Furthermore, programs should be configured by the Debian
8002 default installation to behave as closely to the upstream
8003 default behavior as possible.
8007 Therefore, if a program in a Debian package needs to be
8008 configured in some way in order to operate sensibly, that
8009 should be done using a site-wide configuration file placed
8010 in
<file>/etc
</file>. Only if the program doesn't support a
8011 site-wide default configuration and the package maintainer
8012 doesn't have time to add it may a default per-user file be
8013 placed in
<file>/etc/skel
</file>.
8017 <file>/etc/skel
</file> should be as empty as we can make it.
8018 This is particularly true because there is no easy (or
8019 necessarily desirable) mechanism for ensuring that the
8020 appropriate dotfiles are copied into the accounts of
8021 existing users when a package is installed.
8027 <heading>Log files
</heading>
8029 Log files should usually be named
8030 <file>/var/log/
<var>package
</var>.log
</file>. If you have many
8031 log files, or need a separate directory for permission
8032 reasons (
<file>/var/log
</file> is writable only by
8033 <file>root
</file>), you should usually create a directory named
8034 <file>/var/log/
<var>package
</var></file> and place your log
8039 Log files must be rotated occasionally so that they don't
8040 grow indefinitely; the best way to do this is to drop a log
8041 rotation configuration file into the directory
8042 <file>/etc/logrotate.d
</file> and use the facilities provided by
8043 logrotate.
<footnote>
8045 The traditional approach to log files has been to set up
8046 <em>ad hoc
</em> log rotation schemes using simple shell
8047 scripts and cron. While this approach is highly
8048 customizable, it requires quite a lot of sysadmin work.
8049 Even though the original Debian system helped a little
8050 by automatically installing a system which can be used
8051 as a template, this was deemed not enough.
8055 The use of
<prgn>logrotate
</prgn>, a program developed
8056 by Red Hat, is better, as it centralizes log management.
8057 It has both a configuration file
8058 (
<file>/etc/logrotate.conf
</file>) and a directory where
8059 packages can drop their individual log rotation
8060 configurations (
<file>/etc/logrotate.d
</file>).
8063 Here is a good example for a logrotate config
8064 file (for more information see
<manref name=
"logrotate"
8066 <example compact=
"compact">
8067 /var/log/foo/*.log {
8072 /etc/init.d/foo force-reload
8076 This rotates all files under
<file>/var/log/foo
</file>, saves
12
8077 compressed generations, and forces the daemon to reload its
8078 configuration information after the log rotation.
8082 Log files should be removed when the package is
8083 purged (but not when it is only removed). This should be
8084 done by the
<prgn>postrm
</prgn> script when it is called
8085 with the argument
<tt>purge
</tt> (see
<ref
8086 id=
"removedetails">).
8091 <heading>Permissions and owners
</heading>
8094 The rules in this section are guidelines for general use.
8095 If necessary you may deviate from the details below.
8096 However, if you do so you must make sure that what is done
8097 is secure and you should try to be as consistent as possible
8098 with the rest of the system. You should probably also
8099 discuss it on
<prgn>debian-devel
</prgn> first.
8103 Files should be owned by
<tt>root:root
</tt>, and made
8104 writable only by the owner and universally readable (and
8105 executable, if appropriate), that is mode
644 or
755.
8109 Directories should be mode
755 or (for group-writability)
8110 mode
2775. The ownership of the directory should be
8111 consistent with its mode: if a directory is mode
2775, it
8112 should be owned by the group that needs write access to
8115 When a package is upgraded, and the owner or permissions
8116 of a file included in the package has changed, dpkg
8117 arranges for the ownership and permissions to be
8118 correctly set upon installation. However, this does not
8119 extend to directories; the permissions and ownership of
8120 directories already on the system does not change on
8121 install or upgrade of packages. This makes sense, since
8122 otherwise common directories like
<tt>/usr
</tt> would
8123 always be in flux. To correctly change permissions of a
8124 directory the package owns, explicit action is required,
8125 usually in the
<tt>postinst
</tt> script. Care must be
8126 taken to handle downgrades as well, in that case.
8133 Setuid and setgid executables should be mode
4755 or
2755
8134 respectively, and owned by the appropriate user or group.
8135 They should not be made unreadable (modes like
4711 or
8136 2711 or even
4111); doing so achieves no extra security,
8137 because anyone can find the binary in the freely available
8138 Debian package; it is merely inconvenient. For the same
8139 reason you should not restrict read or execute permissions
8140 on non-set-id executables.
8144 Some setuid programs need to be restricted to particular
8145 sets of users, using file permissions. In this case they
8146 should be owned by the uid to which they are set-id, and by
8147 the group which should be allowed to execute them. They
8148 should have mode
4754; again there is no point in making
8149 them unreadable to those users who must not be allowed to
8154 It is possible to arrange that the system administrator can
8155 reconfigure the package to correspond to their local
8156 security policy by changing the permissions on a binary:
8157 they can do this by using
<prgn>dpkg-statoverride
</prgn>, as
8158 described below.
<footnote>
8159 Ordinary files installed by
<prgn>dpkg
</prgn> (as
8160 opposed to
<tt>conffile
</tt>s and other similar objects)
8161 normally have their permissions reset to the distributed
8162 permissions when the package is reinstalled. However,
8163 the use of
<prgn>dpkg-statoverride
</prgn> overrides this
8166 Another method you should consider is to create a group for
8167 people allowed to use the program(s) and make any setuid
8168 executables executable only by that group.
8172 If you need to create a new user or group for your package
8173 there are two possibilities. Firstly, you may need to
8174 make some files in the binary package be owned by this
8175 user or group, or you may need to compile the user or
8176 group id (rather than just the name) into the binary
8177 (though this latter should be avoided if possible, as in
8178 this case you need a statically allocated id).
</p>
8181 If you need a statically allocated id, you must ask for a
8182 user or group id from the
<tt>base-passwd
</tt> maintainer,
8183 and must not release the package until you have been
8184 allocated one. Once you have been allocated one you must
8185 either make the package depend on a version of the
8186 <tt>base-passwd
</tt> package with the id present in
8187 <file>/etc/passwd
</file> or
<file>/etc/group
</file>, or arrange for
8188 your package to create the user or group itself with the
8189 correct id (using
<tt>adduser
</tt>) in its
8190 <prgn>preinst
</prgn> or
<prgn>postinst
</prgn>. (Doing it in
8191 the
<prgn>postinst
</prgn> is to be preferred if it is
8192 possible, otherwise a pre-dependency will be needed on the
8193 <tt>adduser
</tt> package.)
8197 On the other hand, the program might be able to determine
8198 the uid or gid from the user or group name at runtime, so
8199 that a dynamically allocated id can be used. In this case
8200 you should choose an appropriate user or group name,
8201 discussing this on
<prgn>debian-devel
</prgn> and checking
8202 with the
<package/base-passwd/ maintainer that it is unique and that
8203 they do not wish you to use a statically allocated id
8204 instead. When this has been checked you must arrange for
8205 your package to create the user or group if necessary using
8206 <prgn>adduser
</prgn> in the
<prgn>preinst
</prgn> or
8207 <prgn>postinst
</prgn> script (again, the latter is to be
8208 preferred if it is possible).
8212 Note that changing the numeric value of an id associated
8213 with a name is very difficult, and involves searching the
8214 file system for all appropriate files. You need to think
8215 carefully whether a static or dynamic id is required, since
8216 changing your mind later will cause problems.
8219 <sect1><heading>The use of
<prgn>dpkg-statoverride
</prgn></heading>
8221 This section is not intended as policy, but as a
8222 description of the use of
<prgn>dpkg-statoverride
</prgn>.
8226 If a system administrator wishes to have a file (or
8227 directory or other such thing) installed with owner and
8228 permissions different from those in the distributed Debian
8229 package, they can use the
<prgn>dpkg-statoverride
</prgn>
8230 program to instruct
<prgn>dpkg
</prgn> to use the different
8231 settings every time the file is installed. Thus the
8232 package maintainer should distribute the files with their
8233 normal permissions, and leave it for the system
8234 administrator to make any desired changes. For example, a
8235 daemon which is normally required to be setuid root, but
8236 in certain situations could be used without being setuid,
8237 should be installed setuid in the
<tt>.deb
</tt>. Then the
8238 local system administrator can change this if they wish.
8239 If there are two standard ways of doing it, the package
8240 maintainer can use
<tt>debconf
</tt> to find out the
8241 preference, and call
<prgn>dpkg-statoverride
</prgn> in the
8242 maintainer script if necessary to accommodate the system
8243 administrator's choice. Care must be taken during
8244 upgrades to not override an existing setting.
8248 Given the above,
<prgn>dpkg-statoverride
</prgn> is
8249 essentially a tool for system administrators and would not
8250 normally be needed in the maintainer scripts. There is
8251 one type of situation, though, where calls to
8252 <prgn>dpkg-statoverride
</prgn> would be needed in the
8253 maintainer scripts, and that involves packages which use
8254 dynamically allocated user or group ids. In such a
8255 situation, something like the following idiom can be very
8256 helpful in the package's
<prgn>postinst
</prgn>, where
8257 <tt>sysuser
</tt> is a dynamically allocated id:
8259 for i in /usr/bin/foo /usr/sbin/bar
8261 # only do something when no setting exists
8262 if ! dpkg-statoverride --list $i
>/dev/null
2>&
1
8264 #include: debconf processing, question about foo and bar
8265 if [
"$RET" =
"true" ] ; then
8266 dpkg-statoverride --update --add sysuser root
4755 $i
8271 The corresponding code to remove the override when the package
8274 for i in /usr/bin/foo /usr/sbin/bar
8276 if dpkg-statoverride --list $i
>/dev/null
2>&
1
8278 dpkg-statoverride --remove $i
8288 <chapt id=
"customized-programs">
8289 <heading>Customized programs
</heading>
8291 <sect id=
"arch-spec">
8292 <heading>Architecture specification strings
</heading>
8295 If a program needs to specify an
<em>architecture specification
8296 string
</em> in some place, it should select one of the strings
8297 provided by
<tt>dpkg-architecture -L
</tt>. The strings are in
8298 the format
<tt><var>os
</var>-
<var>arch
</var></tt>, though the OS
8299 part is sometimes elided, as when the OS is Linux.
8303 Note that we don't want to use
8304 <tt><var>arch
</var>-debian-linux
</tt> to apply to the rule
8305 <tt><var>architecture
</var>-
<var>vendor
</var>-
<var>os
</var></tt>
8306 since this would make our programs incompatible with other
8307 Linux distributions. We also don't use something like
8308 <tt><var>arch
</var>-unknown-linux
</tt>, since the
8309 <tt>unknown
</tt> does not look very good.
8312 <sect1 id=
"arch-wildcard-spec">
8313 <heading>Architecture wildcards
</heading>
8316 A package may specify an architecture wildcard. Architecture
8317 wildcards are in the format
<tt>any
</tt> (which matches every
8318 architecture),
<tt><var>os
</var></tt>-any, or
8319 any-
<tt><var>cpu
</var></tt>.
<footnote>
8320 Internally, the package system normalizes the GNU triplets
8321 and the Debian arches into Debian arch triplets (which are
8322 kind of inverted GNU triplets), with the first component of
8323 the triplet representing the libc and ABI in use, and then
8324 does matching against those triplets. However, such
8325 triplets are an internal implementation detail that should
8326 not be used by packages directly. The libc and ABI portion
8327 is handled internally by the package system based on
8328 the
<var>os
</var> and
<var>cpu
</var>.
8335 <heading>Daemons
</heading>
8338 The configuration files
<file>/etc/services
</file>,
8339 <file>/etc/protocols
</file>, and
<file>/etc/rpc
</file> are managed
8340 by the
<prgn>netbase
</prgn> package and must not be modified
8345 If a package requires a new entry in one of these files, the
8346 maintainer should get in contact with the
8347 <prgn>netbase
</prgn> maintainer, who will add the entries
8348 and release a new version of the
<prgn>netbase
</prgn>
8353 The configuration file
<file>/etc/inetd.conf
</file> must not be
8354 modified by the package's scripts except via the
8355 <prgn>update-inetd
</prgn> script or the
8356 <file>DebianNet.pm
</file> Perl module. See their documentation
8357 for details on how to add entries.
8361 If a package wants to install an example entry into
8362 <file>/etc/inetd.conf
</file>, the entry must be preceded with
8363 exactly one hash character (
<tt>#
</tt>). Such lines are
8364 treated as
"commented out by user" by the
8365 <prgn>update-inetd
</prgn> script and are not changed or
8366 activated during package updates.
8371 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8375 Some programs need to create pseudo-ttys. This should be done
8376 using Unix98 ptys if the C library supports it. The resulting
8377 program must not be installed setuid root, unless that
8378 is required for other functionality.
8382 The files
<file>/var/run/utmp
</file>,
<file>/var/log/wtmp
</file> and
8383 <file>/var/log/lastlog
</file> must be installed writable by
8384 group
<tt>utmp
</tt>. Programs which need to modify those
8385 files must be installed setgid
<tt>utmp
</tt>.
8390 <heading>Editors and pagers
</heading>
8393 Some programs have the ability to launch an editor or pager
8394 program to edit or display a text document. Since there are
8395 lots of different editors and pagers available in the Debian
8396 distribution, the system administrator and each user should
8397 have the possibility to choose their preferred editor and
8402 In addition, every program should choose a good default
8403 editor/pager if none is selected by the user or system
8408 Thus, every program that launches an editor or pager must
8409 use the EDITOR or PAGER environment variable to determine
8410 the editor or pager the user wishes to use. If these
8411 variables are not set, the programs
<file>/usr/bin/editor
</file>
8412 and
<file>/usr/bin/pager
</file> should be used, respectively.
8416 These two files are managed through the
<prgn>dpkg
</prgn>
8417 "alternatives" mechanism. Every package providing an editor or
8418 pager must call the
<prgn>update-alternatives
</prgn> script to
8419 register as an alternative for
<file>/usr/bin/editor
</file>
8420 or
<file>/usr/bin/pager
</file> as appropriate. The alternative
8421 should have a slave alternative
8422 for
<file>/usr/share/man/man1/editor
.1.gz
</file>
8423 or
<file>/usr/share/man/man1/pager
.1.gz
</file> pointing to the
8424 corresponding manual page.
8428 If it is very hard to adapt a program to make use of the
8429 EDITOR or PAGER variables, that program may be configured to
8430 use
<file>/usr/bin/sensible-editor
</file> and
8431 <file>/usr/bin/sensible-pager
</file> as the editor or pager
8432 program respectively. These are two scripts provided in the
8433 <package>sensible-utils
</package> package that check the EDITOR
8434 and PAGER variables and launch the appropriate program, and fall
8435 back to
<file>/usr/bin/editor
</file>
8436 and
<file>/usr/bin/pager
</file> if the variable is not set.
8440 A program may also use the VISUAL environment variable to
8441 determine the user's choice of editor. If it exists, it
8442 should take precedence over EDITOR. This is in fact what
8443 <file>/usr/bin/sensible-editor
</file> does.
8447 It is not required for a package to depend on
8448 <tt>editor
</tt> and
<tt>pager
</tt>, nor is it required for a
8449 package to provide such virtual packages.
<footnote>
8450 The Debian base system already provides an editor and a
8456 <sect id=
"web-appl">
8457 <heading>Web servers and applications
</heading>
8460 This section describes the locations and URLs that should
8461 be used by all web servers and web applications in the
8468 Cgi-bin executable files are installed in the
8470 <example compact=
"compact">
8471 /usr/lib/cgi-bin/
<var>cgi-bin-name
</var>
8473 or a subdirectory of that directory, and should be
8475 <example compact=
"compact">
8476 http://localhost/cgi-bin/
<var>cgi-bin-name
</var>
8478 (possibly with a subdirectory name
8479 before
<var>cgi-bin-name
</var>).
8483 <p>Access to HTML documents
</p>
8486 HTML documents for a package are stored in
8487 <file>/usr/share/doc/
<var>package
</var></file>
8488 and can be referred to as
8489 <example compact=
"compact">
8490 http://localhost/doc/
<var>package
</var>/
<var>filename
</var>
8495 The web server should restrict access to the document
8496 tree so that only clients on the same host can read
8497 the documents. If the web server does not support such
8498 access controls, then it should not provide access at
8499 all, or ask about providing access during installation.
8504 <p>Access to images
</p>
8506 It is recommended that images for a package be stored
8507 in
<tt>/usr/share/images/
<var>package
</var></tt> and
8508 may be referred to through an alias
<tt>/images/
</tt>
8511 http://localhost/images/
<package
>/
<filename
>
8518 <p>Web Document Root
</p>
8521 Web Applications should try to avoid storing files in
8522 the Web Document Root. Instead they should use the
8523 /usr/share/doc/
<var>package
</var> directory for
8524 documents and register the Web Application via the
8525 <package>doc-base
</package> package. If access to the
8526 web document root is unavoidable then use
8527 <example compact=
"compact">
8530 as the Document Root. This might be just a symbolic
8531 link to the location where the system administrator
8532 has put the real document root.
8535 <item><p>Providing httpd and/or httpd-cgi
</p>
8537 All web servers should provide the virtual package
8538 <tt>httpd
</tt>. If a web server has CGI support it should
8539 provide
<tt>httpd-cgi
</tt> additionally.
8542 All web applications which do not contain CGI scripts should
8543 depend on
<tt>httpd
</tt>, all those web applications which
8544 <tt>do
</tt> contain CGI scripts, should depend on
8552 <sect id=
"mail-transport-agents">
8553 <heading>Mail transport, delivery and user agents
</heading>
8556 Debian packages which process electronic mail, whether mail
8557 user agents (MUAs) or mail transport agents (MTAs), must
8558 ensure that they are compatible with the configuration
8559 decisions below. Failure to do this may result in lost
8560 mail, broken
<tt>From:
</tt> lines, and other serious brain
8565 The mail spool is
<file>/var/mail
</file> and the interface to
8566 send a mail message is
<file>/usr/sbin/sendmail
</file> (as per
8567 the FHS). On older systems, the mail spool may be
8568 physically located in
<file>/var/spool/mail
</file>, but all
8569 access to the mail spool should be via the
8570 <file>/var/mail
</file> symlink. The mail spool is part of the
8571 base system and not part of the MTA package.
8575 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8576 programs (such as IMAP daemons) must lock the mailbox in an
8577 NFS-safe way. This means that
<tt>fcntl()
</tt> locking must
8578 be combined with dot locking. To avoid deadlocks, a program
8579 should use
<tt>fcntl()
</tt> first and dot locking after
8580 this, or alternatively implement the two locking methods in
8581 a non blocking way
<footnote>
8582 If it is not possible to establish both locks, the
8583 system shouldn't wait for the second lock to be
8584 established, but remove the first lock, wait a (random)
8585 time, and start over locking again.
8586 </footnote>. Using the functions
<tt>maillock
</tt> and
8587 <tt>mailunlock
</tt> provided by the
8588 <tt>liblockfile*
</tt><footnote>
8589 You will need to depend on
<tt>liblockfile1 (
>>1.01)
</tt>
8590 to use these functions.
8591 </footnote> packages is the recommended way to realize this.
8595 Mailboxes are generally either mode
600 and owned by
8596 <var>user
</var> or mode
660 and owned by
8597 <tt><var>user
</var>:mail
</tt><footnote>
8598 There are two traditional permission schemes for mail spools:
8599 mode
600 with all mail delivery done by processes running as
8600 the destination user, or mode
660 and owned by group mail with
8601 mail delivery done by a process running as a system user in
8602 group mail. Historically, Debian required mode
660 mail
8603 spools to enable the latter model, but that model has become
8604 increasingly uncommon and the principle of least privilege
8605 indicates that mail systems that use the first model should
8606 use permissions of
600. If delivery to programs is permitted,
8607 it's easier to keep the mail system secure if the delivery
8608 agent runs as the destination user. Debian Policy therefore
8609 permits either scheme.
8610 </footnote>. The local system administrator may choose a
8611 different permission scheme; packages should not make
8612 assumptions about the permission and ownership of mailboxes
8613 unless required (such as when creating a new mailbox). A MUA
8614 may remove a mailbox (unless it has nonstandard permissions) in
8615 which case the MTA or another MUA must recreate it if needed.
8619 The mail spool is
2775 <tt>root:mail
</tt>, and MUAs should
8620 be setgid mail to do the locking mentioned above (and
8621 must obviously avoid accessing other users' mailboxes
8622 using this privilege).
</p>
8625 <file>/etc/aliases
</file> is the source file for the system mail
8626 aliases (e.g., postmaster, usenet, etc.), it is the one
8627 which the sysadmin and
<prgn>postinst
</prgn> scripts may
8628 edit. After
<file>/etc/aliases
</file> is edited the program or
8629 human editing it must call
<prgn>newaliases
</prgn>. All MTA
8630 packages must come with a
<prgn>newaliases
</prgn> program,
8631 even if it does nothing, but older MTA packages did not do
8632 this so programs should not fail if
<prgn>newaliases
</prgn>
8633 cannot be found. Note that because of this, all MTA
8634 packages must have
<tt>Provides
</tt>,
<tt>Conflicts
</tt> and
8635 <tt>Replaces: mail-transport-agent
</tt> control fields.
8639 The convention of writing
<tt>forward to
8640 <var>address
</var></tt> in the mailbox itself is not
8641 supported. Use a
<tt>.forward
</tt> file instead.
</p>
8644 The
<prgn>rmail
</prgn> program used by UUCP
8645 for incoming mail should be
<file>/usr/sbin/rmail
</file>.
8646 Likewise,
<prgn>rsmtp
</prgn>, for receiving
8647 batch-SMTP-over-UUCP, should be
<file>/usr/sbin/rsmtp
</file> if it
8651 If your package needs to know what hostname to use on (for
8652 example) outgoing news and mail messages which are generated
8653 locally, you should use the file
<file>/etc/mailname
</file>. It
8654 will contain the portion after the username and
<tt>@
</tt>
8655 (at) sign for email addresses of users on the machine
8656 (followed by a newline).
8660 Such a package should check for the existence of this file
8661 when it is being configured. If it exists, it should be
8662 used without comment, although an MTA's configuration script
8663 may wish to prompt the user even if it finds that this file
8664 exists. If the file does not exist, the package should
8665 prompt the user for the value (preferably using
8666 <prgn>debconf
</prgn>) and store it in
<file>/etc/mailname
</file>
8667 as well as using it in the package's configuration. The
8668 prompt should make it clear that the name will not just be
8669 used by that package. For example, in this situation the
8670 <tt>inn
</tt> package could say something like:
8671 <example compact=
"compact">
8672 Please enter the
"mail name" of your system. This is the
8673 hostname portion of the address to be shown on outgoing
8674 news and mail messages. The default is
8675 <var>syshostname
</var>, your system's host name. Mail
8676 name [
"<var>syshostname</var>"]:
8678 where
<var>syshostname
</var> is the output of
<tt>hostname
8684 <heading>News system configuration
</heading>
8687 All the configuration files related to the NNTP (news)
8688 servers and clients should be located under
8689 <file>/etc/news
</file>.
</p>
8692 There are some configuration issues that apply to a number
8693 of news clients and server packages on the machine. These
8697 <tag><file>/etc/news/organization
</file></tag>
8699 A string which should appear as the
8700 organization header for all messages posted
8701 by NNTP clients on the machine
8704 <tag><file>/etc/news/server
</file></tag>
8706 Contains the FQDN of the upstream NNTP
8707 server, or localhost if the local machine is
8712 Other global files may be added as required for cross-package news
8719 <heading>Programs for the X Window System
</heading>
8722 <heading>Providing X support and package priorities
</heading>
8725 Programs that can be configured with support for the X
8726 Window System must be configured to do so and must declare
8727 any package dependencies necessary to satisfy their
8728 runtime requirements when using the X Window System. If
8729 such a package is of higher priority than the X packages
8730 on which it depends, it is required that either the
8731 X-specific components be split into a separate package, or
8732 that an alternative version of the package, which includes
8733 X support, be provided, or that the package's priority be
8739 <heading>Packages providing an X server
</heading>
8742 Packages that provide an X server that, directly or
8743 indirectly, communicates with real input and display
8744 hardware should declare in their
<tt>Provides
</tt> control
8745 field that they provide the virtual
8746 package
<tt>xserver
</tt>.
<footnote>
8747 This implements current practice, and provides an
8748 actual policy for usage of the
<tt>xserver
</tt>
8749 virtual package which appears in the virtual packages
8750 list. In a nutshell, X servers that interface
8751 directly with the display and input hardware or via
8752 another subsystem (e.g., GGI) should provide
8753 <tt>xserver
</tt>. Things like
<tt>Xvfb
</tt>,
8754 <tt>Xnest
</tt>, and
<tt>Xprt
</tt> should not.
8760 <heading>Packages providing a terminal emulator
</heading>
8763 Packages that provide a terminal emulator for the X Window
8764 System which meet the criteria listed below should declare in
8765 their
<tt>Provides
</tt> control field that they provide the
8766 virtual package
<tt>x-terminal-emulator
</tt>. They should
8767 also register themselves as an alternative for
8768 <file>/usr/bin/x-terminal-emulator
</file>, with a priority of
8769 20. That alternative should have a slave alternative
8770 for
<file>/usr/share/man/man1/x-terminal-emulator
.1.gz
</file>
8771 pointing to the corresponding manual page.
8775 To be an
<tt>x-terminal-emulator
</tt>, a program must:
8776 <list compact=
"compact">
8778 Be able to emulate a DEC VT100 terminal, or a
8779 compatible terminal.
8783 Support the command-line option
<tt>-e
8784 <var>command
</var></tt>, which creates a new
8785 terminal window
<footnote>
8786 "New terminal window" does not necessarily mean
8787 a new top-level X window directly parented by
8788 the window manager; it could, if the terminal
8789 emulator application were so coded, be a new
8790 "view" in a multiple-document interface (MDI).
8792 and runs the specified
<var>command
</var>,
8793 interpreting the entirety of the rest of the command
8794 line as a command to pass straight to exec, in the
8795 manner that
<tt>xterm
</tt> does.
8799 Support the command-line option
<tt>-T
8800 <var>title
</var></tt>, which creates a new terminal
8801 window with the window title
<var>title
</var>.
8808 <heading>Packages providing a window manager
</heading>
8811 Packages that provide a window manager should declare in
8812 their
<tt>Provides
</tt> control field that they provide the
8813 virtual package
<tt>x-window-manager
</tt>. They should also
8814 register themselves as an alternative for
8815 <file>/usr/bin/x-window-manager
</file>, with a priority
8816 calculated as follows:
8817 <list compact=
"compact">
8819 Start with a priority of
20.
8823 If the window manager supports the Debian menu
8824 system, add
20 points if this support is available
8825 in the package's default configuration (i.e., no
8826 configuration files belonging to the system or user
8827 have to be edited to activate the feature); if
8828 configuration files must be modified, add only
10
8834 If the window manager complies with
<url
8835 id=
"http://www.freedesktop.org/Standards/wm-spec"
8836 name=
"The Window Manager Specification Project">,
8837 written by the
<url id=
"http://www.freedesktop.org/"
8838 name=
"Free Desktop Group">, add
40 points.
8842 If the window manager permits the X session to be
8843 restarted using a
<em>different
</em> window manager
8844 (without killing the X server) in its default
8845 configuration, add
10 points; otherwise add none.
8848 That alternative should have a slave alternative
8849 for
<file>/usr/share/man/man1/x-window-manager
.1.gz
</file>
8850 pointing to the corresponding manual page.
8855 <heading>Packages providing fonts
</heading>
8858 Packages that provide fonts for the X Window
8860 For the purposes of Debian Policy, a
"font for the X
8861 Window System" is one which is accessed via X protocol
8862 requests. Fonts for the Linux console, for PostScript
8863 renderer, or any other purpose, do not fit this
8864 definition. Any tool which makes such fonts available
8865 to the X Window System, however, must abide by this
8868 must do a number of things to ensure that they are both
8869 available without modification of the X or font server
8870 configuration, and that they do not corrupt files used by
8871 other font packages to register information about
8875 Fonts of any type supported by the X Window System
8876 must be in a separate binary package from any
8877 executables, libraries, or documentation (except
8878 that specific to the fonts shipped, such as their
8879 license information). If one or more of the fonts
8880 so packaged are necessary for proper operation of
8881 the package with which they are associated the font
8882 package may be Recommended; if the fonts merely
8883 provide an enhancement, a Suggests relationship may
8884 be used. Packages must not Depend on font
8886 This is because the X server may retrieve fonts
8887 from the local file system or over the network
8888 from an X font server; the Debian package system
8889 is empowered to deal only with the local
8895 BDF fonts must be converted to PCF fonts with the
8896 <prgn>bdftopcf
</prgn> utility (available in the
8897 <tt>xfonts-utils
</tt> package,
<prgn>gzip
</prgn>ped, and
8898 placed in a directory that corresponds to their
8900 <list compact=
"compact">
8902 100 dpi fonts must be placed in
8903 <file>/usr/share/fonts/X11/
100dpi/
</file>.
8907 75 dpi fonts must be placed in
8908 <file>/usr/share/fonts/X11/
75dpi/
</file>.
8912 Character-cell fonts, cursor fonts, and other
8913 low-resolution fonts must be placed in
8914 <file>/usr/share/fonts/X11/misc/
</file>.
8920 Type
1 fonts must be placed in
8921 <file>/usr/share/fonts/X11/Type1/
</file>. If font
8922 metric files are available, they must be placed here
8927 Subdirectories of
<file>/usr/share/fonts/X11/
</file>
8928 other than those listed above must be neither
8929 created nor used. (The
<file>PEX
</file>,
<file>CID
</file>,
8930 <file>Speedo
</file>, and
<file>cyrillic
</file> directories
8931 are excepted for historical reasons, but installation of
8932 files into these directories remains discouraged.)
8936 Font packages may, instead of placing files directly
8937 in the X font directories listed above, provide
8938 symbolic links in that font directory pointing to
8939 the files' actual location in the filesystem. Such
8940 a location must comply with the FHS.
8944 Font packages should not contain both
75dpi and
8945 100dpi versions of a font. If both are available,
8946 they should be provided in separate binary packages
8947 with
<tt>-
75dpi
</tt> or
<tt>-
100dpi
</tt> appended to
8948 the names of the packages containing the
8949 corresponding fonts.
8953 Fonts destined for the
<file>misc
</file> subdirectory
8954 should not be included in the same package as
75dpi
8955 or
100dpi fonts; instead, they should be provided in
8956 a separate package with
<tt>-misc
</tt> appended to
8961 Font packages must not provide the files
8962 <file>fonts.dir
</file>,
<file>fonts.alias
</file>, or
8963 <file>fonts.scale
</file> in a font directory:
8966 <file>fonts.dir
</file> files must not be provided at all.
8970 <file>fonts.alias
</file> and
<file>fonts.scale
</file>
8971 files, if needed, should be provided in the
8973 <file>/etc/X11/fonts/
<var>fontdir
</var>/
<var>package
</var>.
<var>extension
</var></file>,
8974 where
<var>fontdir
</var> is the name of the
8976 <file>/usr/share/fonts/X11/
</file> where the
8977 package's corresponding fonts are stored
8978 (e.g.,
<tt>75dpi
</tt> or
<tt>misc
</tt>),
8979 <var>package
</var> is the name of the package
8980 that provides these fonts, and
8981 <var>extension
</var> is either
<tt>scale
</tt>
8982 or
<tt>alias
</tt>, whichever corresponds to
8989 Font packages must declare a dependency on
8990 <tt>xfonts-utils
</tt> in their
<tt>Depends
</tt>
8991 or
<tt>Pre-Depends
</tt> control field.
8995 Font packages that provide one or more
8996 <file>fonts.scale
</file> files as described above must
8997 invoke
<prgn>update-fonts-scale
</prgn> on each
8998 directory into which they installed fonts
8999 <em>before
</em> invoking
9000 <prgn>update-fonts-dir
</prgn> on that directory.
9001 This invocation must occur in both the
9002 <prgn>postinst
</prgn> (for all arguments) and
9003 <prgn>postrm
</prgn> (for all arguments except
9004 <tt>upgrade
</tt>) scripts.
9008 Font packages that provide one or more
9009 <file>fonts.alias
</file> files as described above must
9010 invoke
<prgn>update-fonts-alias
</prgn> on each
9011 directory into which they installed fonts. This
9012 invocation must occur in both the
9013 <prgn>postinst
</prgn> (for all arguments) and
9014 <prgn>postrm
</prgn> (for all arguments except
9015 <tt>upgrade
</tt>) scripts.
9019 Font packages must invoke
9020 <prgn>update-fonts-dir
</prgn> on each directory into
9021 which they installed fonts. This invocation must
9022 occur in both the
<prgn>postinst
</prgn> (for all
9023 arguments) and
<prgn>postrm
</prgn> (for all
9024 arguments except
<tt>upgrade
</tt>) scripts.
9028 Font packages must not provide alias names for the
9029 fonts they include which collide with alias names
9030 already in use by fonts already packaged.
9034 Font packages must not provide fonts with the same
9035 XLFD registry name as another font already packaged.
9041 <sect1 id=
"appdefaults">
9042 <heading>Application defaults files
</heading>
9045 Application defaults files must be installed in the
9046 directory
<file>/etc/X11/app-defaults/
</file> (use of a
9047 localized subdirectory of
<file>/etc/X11/
</file> as described
9048 in the
<em>X Toolkit Intrinsics - C Language
9049 Interface
</em> manual is also permitted). They must be
9050 registered as
<tt>conffile
</tt>s or handled as
9051 configuration files.
9055 Customization of programs' X resources may also be
9056 supported with the provision of a file with the same name
9057 as that of the package placed in
9058 the
<file>/etc/X11/Xresources/
</file> directory, which
9059 must be registered as a
<tt>conffile
</tt> or handled as a
9060 configuration file.
<footnote>
9061 Note that this mechanism is not the same as using
9062 app-defaults; app-defaults are tied to the client
9063 binary on the local file system, whereas X resources
9064 are stored in the X server and affect all connecting
9071 <heading>Installation directory issues
</heading>
9074 Historically, packages using the X Window System used a
9075 separate set of installation directories from other packages.
9076 This practice has been discontinued and packages using the X
9077 Window System should now generally be installed in the same
9078 directories as any other package. Specifically, packages must
9079 not install files under the
<file>/usr/X11R6/
</file> directory
9080 and the
<file>/usr/X11R6/
</file> directory hierarchy should be
9081 regarded as obsolete.
9085 Include files previously installed under
9086 <file>/usr/X11R6/include/X11/
</file> should be installed into
9087 <file>/usr/include/X11/
</file>. For files previously
9088 installed into subdirectories of
9089 <file>/usr/X11R6/lib/X11/
</file>, package maintainers should
9090 determine if subdirectories of
<file>/usr/lib/
</file> and
9091 <file>/usr/share/
</file> can be used. If not, a subdirectory
9092 of
<file>/usr/lib/X11/
</file> should be used.
9096 Configuration files for window, display, or session managers
9097 or other applications that are tightly integrated with the X
9098 Window System may be placed in a subdirectory
9099 of
<file>/etc/X11/
</file> corresponding to the package name.
9100 Other X Window System applications should use
9101 the
<file>/etc/
</file> directory unless otherwise mandated by
9102 policy (such as for
<ref id=
"appdefaults">).
9107 <heading>The OSF/Motif and OpenMotif libraries
</heading>
9110 <em>Programs that require the non-DFSG-compliant OSF/Motif or
9111 OpenMotif libraries
</em><footnote>
9112 OSF/Motif and OpenMotif are collectively referred to as
9113 "Motif" in this policy document.
9115 should be compiled against and tested with LessTif (a free
9116 re-implementation of Motif) instead. If the maintainer
9117 judges that the program or programs do not work
9118 sufficiently well with LessTif to be distributed and
9119 supported, but do so when compiled against Motif, then two
9120 versions of the package should be created; one linked
9121 statically against Motif and with
<tt>-smotif
</tt>
9122 appended to the package name, and one linked dynamically
9123 against Motif and with
<tt>-dmotif
</tt> appended to the
9128 Both Motif-linked versions are dependent
9129 upon non-DFSG-compliant software and thus cannot be
9130 uploaded to the
<em>main
</em> distribution; if the
9131 software is itself DFSG-compliant it may be uploaded to
9132 the
<em>contrib
</em> distribution. While known existing
9133 versions of Motif permit unlimited redistribution of
9134 binaries linked against the library (whether statically or
9135 dynamically), it is the package maintainer's
9136 responsibility to determine whether this is permitted by
9137 the license of the copy of Motif in their possession.
9143 <heading>Perl programs and modules
</heading>
9146 Perl programs and modules should follow the current Perl policy.
9150 The Perl policy can be found in the
<tt>perl-policy
</tt>
9151 files in the
<tt>debian-policy
</tt> package.
9152 It is also available from the Debian web mirrors at
9153 <tt><url name=
"/doc/packaging-manuals/perl-policy/"
9154 id=
"http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
9159 <heading>Emacs lisp programs
</heading>
9162 Please refer to the
"Debian Emacs Policy" for details of how to
9163 package emacs lisp programs.
9167 The Emacs policy is available in
9168 <file>debian-emacs-policy.gz
</file> of the
9169 <package>emacsen-common
</package> package.
9170 It is also available from the Debian web mirrors at
9171 <tt><url name=
"/doc/packaging-manuals/debian-emacs-policy"
9172 id=
"http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
9177 <heading>Games
</heading>
9180 The permissions on
<file>/var/games
</file> are mode
755, owner
9181 <tt>root
</tt> and group
<tt>root
</tt>.
9185 Each game decides on its own security policy.
</p>
9188 Games which require protected, privileged access to
9189 high-score files, saved games, etc., may be made
9190 set-
<em>group
</em>-id (mode
2755) and owned by
9191 <tt>root:games
</tt>, and use files and directories with
9192 appropriate permissions (
770 <tt>root:games
</tt>, for
9193 example). They must not be made
9194 set-
<em>user
</em>-id, as this causes security problems. (If
9195 an attacker can subvert any set-user-id game they can
9196 overwrite the executable of any other, causing other players
9197 of these games to run a Trojan horse program. With a
9198 set-group-id game the attacker only gets access to less
9199 important game data, and if they can get at the other
9200 players' accounts at all it will take considerably more
9204 Some packages, for example some fortune cookie programs, are
9205 configured by the upstream authors to install with their
9206 data files or other static information made unreadable so
9207 that they can only be accessed through set-id programs
9208 provided. You should not do this in a Debian package: anyone can
9209 download the
<file>.deb
</file> file and read the data from it,
9210 so there is no point making the files unreadable. Not
9211 making the files unreadable also means that you don't have
9212 to make so many programs set-id, which reduces the risk of a
9216 As described in the FHS, binaries of games should be
9217 installed in the directory
<file>/usr/games
</file>. This also
9218 applies to games that use the X Window System. Manual pages
9219 for games (X and non-X games) should be installed in
9220 <file>/usr/share/man/man6
</file>.
</p>
9226 <heading>Documentation
</heading>
9229 <heading>Manual pages
</heading>
9232 You should install manual pages in
<prgn>nroff
</prgn> source
9233 form, in appropriate places under
<file>/usr/share/man
</file>.
9234 You should only use sections
1 to
9 (see the FHS for more
9235 details). You must not install a pre-formatted
"cat page".
9239 Each program, utility, and function should have an
9240 associated manual page included in the same package. It is
9241 suggested that all configuration files also have a manual
9242 page included as well. Manual pages for protocols and other
9243 auxiliary things are optional.
9247 If no manual page is available, this is considered as a bug
9248 and should be reported to the Debian Bug Tracking System (the
9249 maintainer of the package is allowed to write this bug report
9250 themselves, if they so desire). Do not close the bug report
9251 until a proper man page is available.
<footnote>
9252 It is not very hard to write a man page. See the
9253 <url id=
"http://www.schweikhardt.net/man_page_howto.html"
9254 name=
"Man-Page-HOWTO">,
9255 <manref name=
"man" section=
"7">, the examples
9256 created by
<prgn>debmake
</prgn> or
<prgn>dh_make
</prgn>,
9257 the helper program
<prgn>help2man
</prgn>, or the
9258 directory
<file>/usr/share/doc/man-db/examples
</file>.
9263 You may forward a complaint about a missing man page to the
9264 upstream authors, and mark the bug as forwarded in the
9265 Debian bug tracking system. Even though the GNU Project do
9266 not in general consider the lack of a man page to be a bug,
9267 we do; if they tell you that they don't consider it a bug
9268 you should leave the bug in our bug tracking system open
9273 Manual pages should be installed compressed using
<tt>gzip -
9</tt>.
9277 If one man page needs to be accessible via several names it
9278 is better to use a symbolic link than the
<file>.so
</file>
9279 feature, but there is no need to fiddle with the relevant
9280 parts of the upstream source to change from
<file>.so
</file> to
9281 symlinks: don't do it unless it's easy. You should not
9282 create hard links in the manual page directories, nor put
9283 absolute filenames in
<file>.so
</file> directives. The filename
9284 in a
<file>.so
</file> in a man page should be relative to the
9285 base of the man page tree (usually
9286 <file>/usr/share/man
</file>). If you do not create any links
9287 (whether symlinks, hard links, or
<tt>.so
</tt> directives)
9288 in the file system to the alternate names of the man page,
9289 then you should not rely on
<prgn>man
</prgn> finding your
9290 man page under those names based solely on the information in
9291 the man page's header.
<footnote>
9292 Supporting this in
<prgn>man
</prgn> often requires
9293 unreasonable processing time to find a manual page or to
9294 report that none exists, and moves knowledge into man's
9295 database that would be better left in the file system.
9296 This support is therefore deprecated and will cease to
9297 be present in the future.
9302 Manual pages in locale-specific subdirectories of
9303 <file>/usr/share/man
</file> should use either UTF-
8 or the usual
9304 legacy encoding for that language (normally the one corresponding
9305 to the shortest relevant locale name in
9306 <file>/usr/share/i18n/SUPPORTED
</file>). For example, pages under
9307 <file>/usr/share/man/fr
</file> should use either UTF-
8 or
9308 ISO-
8859-
1.
<footnote>
9309 <prgn>man
</prgn> will automatically detect whether UTF-
8 is in
9310 use. In future, all manual pages will be required to use
9316 A country name (the
<tt>DE
</tt> in
<tt>de_DE
</tt>) should not be
9317 included in the subdirectory name unless it indicates a
9318 significant difference in the language, as this excludes
9319 speakers of the language in other countries.
<footnote>
9320 At the time of writing, Chinese and Portuguese are the main
9321 languages with such differences, so
<file>pt_BR
</file>,
9322 <file>zh_CN
</file>, and
<file>zh_TW
</file> are all allowed.
9327 If a localized version of a manual page is provided, it should
9328 either be up-to-date or it should be obvious to the reader that
9329 it is outdated and the original manual page should be used
9330 instead. This can be done either by a note at the beginning of
9331 the manual page or by showing the missing or changed portions in
9332 the original language instead of the target language.
9337 <heading>Info documents
</heading>
9340 Info documents should be installed in
<file>/usr/share/info
</file>.
9341 They should be compressed with
<tt>gzip -
9</tt>.
9345 The
<prgn>install-info
</prgn> program maintains a directory of
9346 installed info documents in
<file>/usr/share/info/dir
</file> for
9347 the use of info readers.
<footnote>
9348 It was previously necessary for packages installing info
9349 documents to run
<prgn>install-info
</prgn> from maintainer
9350 scripts. This is no longer necessary. The installation
9351 system now uses dpkg triggers.
9353 This file must not be included in packages. Packages containing
9354 info documents should depend on
<tt>dpkg (
>=
1.15.4) |
9355 install-info
</tt> to ensure that the directory file is properly
9356 rebuilt during partial upgrades from Debian
5.0 (lenny) and
9361 Info documents should contain section and directory entry
9362 information in the document for the use
9363 of
<prgn>install-info
</prgn>. The section should be specified
9364 via a line starting with
<tt>INFO-DIR-SECTION
</tt> followed by a
9365 space and the section of this info page. The directory entry or
9366 entries should be included between
9367 a
<tt>START-INFO-DIR-ENTRY
</tt> line and
9368 an
<tt>END-INFO-DIR-ENTRY
</tt> line. For example:
9370 INFO-DIR-SECTION Individual utilities
9371 START-INFO-DIR-ENTRY
9372 * example: (example). An example info directory entry.
9375 To determine which section to use, you should look
9376 at
<file>/usr/share/info/dir
</file> on your system and choose
9377 the most relevant (or create a new section if none of the
9378 current sections are relevant).
<footnote>
9379 Normally, info documents are generated from Texinfo source.
9380 To include this information in the generated info document, if
9381 it is absent, add commands like:
9383 @dircategory Individual utilities
9385 * example: (example). An example info directory entry.
9388 to the Texinfo source of the document and ensure that the info
9389 documents are rebuilt from source during the package build.
9395 <heading>Additional documentation
</heading>
9398 Any additional documentation that comes with the package may
9399 be installed at the discretion of the package maintainer.
9400 Plain text documentation should be installed in the directory
9401 <file>/usr/share/doc/
<var>package
</var></file>, where
9402 <var>package
</var> is the name of the package, and
9403 compressed with
<tt>gzip -
9</tt> unless it is small.
9407 If a package comes with large amounts of documentation which
9408 many users of the package will not require you should create
9409 a separate binary package to contain it, so that it does not
9410 take up disk space on the machines of users who do not need
9411 or want it installed.
</p>
9414 It is often a good idea to put text information files
9415 (
<file>README
</file>s, changelogs, and so forth) that come with
9416 the source package in
<file>/usr/share/doc/
<var>package
</var></file>
9417 in the binary package. However, you don't need to install
9418 the instructions for building and installing the package, of
9422 Packages must not require the existence of any files in
9423 <file>/usr/share/doc/
</file> in order to function
9425 The system administrator should be able to
9426 delete files in
<file>/usr/share/doc/
</file> without causing
9427 any programs to break.
9429 Any files that are referenced by programs but are also
9430 useful as stand alone documentation should be installed under
9431 <file>/usr/share/
<var>package
</var>/
</file> with symbolic links from
9432 <file>/usr/share/doc/
<var>package
</var></file>.
9436 <file>/usr/share/doc/
<var>package
</var></file> may be a symbolic
9437 link to another directory in
<file>/usr/share/doc
</file> only if
9438 the two packages both come from the same source and the
9439 first package Depends on the second.
<footnote>
9441 Please note that this does not override the section on
9442 changelog files below, so the file
9443 <file>/usr/share/doc/
<var>package
</var>/changelog.Debian.gz
</file>
9444 must refer to the changelog for the current version of
9445 <var>package
</var> in question. In practice, this means
9446 that the sources of the target and the destination of the
9447 symlink must be the same (same source package and
9454 Former Debian releases placed all additional documentation
9455 in
<file>/usr/doc/
<var>package
</var></file>. This has been
9456 changed to
<file>/usr/share/doc/
<var>package
</var></file>,
9457 and packages must not put documentation in the directory
9458 <file>/usr/doc/
<var>package
</var></file>.
<footnote>
9459 At this phase of the transition, we no longer require a
9460 symbolic link in
<file>/usr/doc/
</file>. At a later point,
9461 policy shall change to make the symbolic links a bug.
9467 <heading>Preferred documentation formats
</heading>
9470 The unification of Debian documentation is being carried out
9474 If your package comes with extensive documentation in a
9475 markup format that can be converted to various other formats
9476 you should if possible ship HTML versions in a binary
9477 package, in the directory
9478 <file>/usr/share/doc/
<var>appropriate-package
</var></file> or
9479 its subdirectories.
<footnote>
9480 The rationale: The important thing here is that HTML
9481 docs should be available in
<em>some
</em> package, not
9482 necessarily in the main binary package.
9487 Other formats such as PostScript may be provided at the
9488 package maintainer's discretion.
9492 <sect id=
"copyrightfile">
9493 <heading>Copyright information
</heading>
9496 Every package must be accompanied by a verbatim copy of its
9497 copyright information and distribution license in the file
9498 <file>/usr/share/doc/
<var>package
</var>/copyright
</file>. This
9499 file must neither be compressed nor be a symbolic link.
9503 In addition, the copyright file must say where the upstream
9504 sources (if any) were obtained. It should name the original
9505 authors of the package and the Debian maintainer(s) who were
9506 involved with its creation.
9510 Packages in the
<em>contrib
</em> or
<em>non-free
</em> archive
9511 areas should state in the copyright file that the package is not
9512 part of the Debian GNU/Linux distribution and briefly explain
9517 A copy of the file which will be installed in
9518 <file>/usr/share/doc/
<var>package
</var>/copyright
</file> should
9519 be in
<file>debian/copyright
</file> in the source package.
9523 <file>/usr/share/doc/
<var>package
</var></file> may be a symbolic
9524 link to another directory in
<file>/usr/share/doc
</file> only if
9525 the two packages both come from the same source and the
9526 first package Depends on the second. These rules are
9527 important because copyrights must be extractable by
9532 Packages distributed under the Apache license (version
2.0), the
9533 Artistic license, the GNU GPL (versions
1,
2, or
3), the GNU
9534 LGPL (versions
2,
2.1, or
3), and the GNU FDL (versions
1.2 or
9535 1.3) should refer to the corresponding files
9536 under
<file>/usr/share/common-licenses
</file>,
<footnote>
9539 <file>/usr/share/common-licenses/Apache-
2.0</file>,
9540 <file>/usr/share/common-licenses/Artistic
</file>,
9541 <file>/usr/share/common-licenses/GPL-
1</file>,
9542 <file>/usr/share/common-licenses/GPL-
2</file>,
9543 <file>/usr/share/common-licenses/GPL-
3</file>,
9544 <file>/usr/share/common-licenses/LGPL-
2</file>,
9545 <file>/usr/share/common-licenses/LGPL-
2.1</file>,
9546 <file>/usr/share/common-licenses/LGPL-
3</file>,
9547 <file>/usr/share/common-licenses/GFDL-
1.2</file>, and
9548 <file>/usr/share/common-licenses/GFDL-
1.3</file>
9549 respectively. The University of California BSD license is
9550 also included in
<package>base-files
</package> as
9551 <file>/usr/share/common-licenses/BSD
</file>, but given the
9552 brevity of this license, its specificity to code whose
9553 copyright is held by the Regents of the University of
9554 California, and the frequency of minor wording changes, its
9555 text should be included in the copyright file rather than
9556 referencing this file.
9558 </footnote> rather than quoting them in the copyright
9563 You should not use the copyright file as a general
<file>README
</file>
9564 file. If your package has such a file it should be
9565 installed in
<file>/usr/share/doc/
<var>package
</var>/README
</file> or
9566 <file>README.Debian
</file> or some other appropriate place.
</p>
9570 <heading>Examples
</heading>
9573 Any examples (configurations, source files, whatever),
9574 should be installed in a directory
9575 <file>/usr/share/doc/
<var>package
</var>/examples
</file>. These
9576 files should not be referenced by any program: they're there
9577 for the benefit of the system administrator and users as
9578 documentation only. Architecture-specific example files
9579 should be installed in a directory
9580 <file>/usr/lib/
<var>package
</var>/examples
</file> with symbolic
9582 <file>/usr/share/doc/
<var>package
</var>/examples
</file>, or the
9583 latter directory itself may be a symbolic link to the
9588 If the purpose of a package is to provide examples, then the
9589 example files may be installed into
9590 <file>/usr/share/doc/
<var>package
</var></file>.
9594 <sect id=
"changelogs">
9595 <heading>Changelog files
</heading>
9598 Packages that are not Debian-native must contain a
9599 compressed copy of the
<file>debian/changelog
</file> file from
9600 the Debian source tree in
9601 <file>/usr/share/doc/
<var>package
</var></file> with the name
9602 <file>changelog.Debian.gz
</file>.
9606 If an upstream changelog is available, it should be accessible as
9607 <file>/usr/share/doc/
<var>package
</var>/changelog.gz
</file> in
9608 plain text. If the upstream changelog is distributed in
9609 HTML, it should be made available in that form as
9610 <file>/usr/share/doc/
<var>package
</var>/changelog.html.gz
</file>
9611 and a plain text
<file>changelog.gz
</file> should be generated
9612 from it using, for example,
<tt>lynx -dump -nolist
</tt>. If
9613 the upstream changelog files do not already conform to this
9614 naming convention, then this may be achieved either by
9615 renaming the files, or by adding a symbolic link, at the
9616 maintainer's discretion.
<footnote>
9617 Rationale: People should not have to look in places for
9618 upstream changelogs merely because they are given
9619 different names or are distributed in HTML format.
9624 All of these files should be installed compressed using
9625 <tt>gzip -
9</tt>, as they will become large with time even
9626 if they start out small.
9630 If the package has only one changelog which is used both as
9631 the Debian changelog and the upstream one because there is
9632 no separate upstream maintainer then that changelog should
9633 usually be installed as
9634 <file>/usr/share/doc/
<var>package
</var>/changelog.gz
</file>; if
9635 there is a separate upstream maintainer, but no upstream
9636 changelog, then the Debian changelog should still be called
9637 <file>changelog.Debian.gz
</file>.
9641 For details about the format and contents of the Debian
9642 changelog file, please see
<ref id=
"dpkgchangelog">.
9647 <appendix id=
"pkg-scope">
9648 <heading>Introduction and scope of these appendices
</heading>
9651 These appendices are taken essentially verbatim from the
9652 now-deprecated Packaging Manual, version
3.2.1.0. They are
9653 the chapters which are likely to be of use to package
9654 maintainers and which have not already been included in the
9655 policy document itself. Most of these sections are very likely
9656 not relevant to policy; they should be treated as
9657 documentation for the packaging system. Please note that these
9658 appendices are included for convenience, and for historical
9659 reasons: they used to be part of policy package, and they have
9660 not yet been incorporated into dpkg documentation. However,
9661 they still have value, and hence they are presented here.
9665 They have not yet been checked to ensure that they are
9666 compatible with the contents of policy, and if there are any
9667 contradictions, the version in the main policy document takes
9668 precedence. The remaining chapters of the old Packaging
9669 Manual have also not been read in detail to ensure that there
9670 are not parts which have been left out. Both of these will be
9675 Certain parts of the Packaging manual were integrated into the
9676 Policy Manual proper, and removed from the appendices. Links
9677 have been placed from the old locations to the new ones.
9681 <prgn>dpkg
</prgn> is a suite of programs for creating binary
9682 package files and installing and removing them on Unix
9684 <prgn>dpkg
</prgn> is targeted primarily at Debian
9685 GNU/Linux, but may work on or be ported to other
9691 The binary packages are designed for the management of
9692 installed executable programs (usually compiled binaries) and
9693 their associated data, though source code examples and
9694 documentation are provided as part of some packages.
</p>
9697 This manual describes the technical aspects of creating Debian
9698 binary packages (
<file>.deb
</file> files). It documents the
9699 behavior of the package management programs
9700 <prgn>dpkg
</prgn>,
<prgn>dselect
</prgn> et al. and the way
9701 they interact with packages.
</p>
9704 It also documents the interaction between
9705 <prgn>dselect
</prgn>'s core and the access method scripts it
9706 uses to actually install the selected packages, and describes
9707 how to create a new access method.
</p>
9710 This manual does not go into detail about the options and
9711 usage of the package building and installation tools. It
9712 should therefore be read in conjunction with those programs'
9717 The utility programs which are provided with
<prgn>dpkg
</prgn>
9718 for managing various system configuration and similar issues,
9719 such as
<prgn>update-rc.d
</prgn> and
9720 <prgn>install-info
</prgn>, are not described in detail here -
9721 please see their man pages.
9725 It is assumed that the reader is reasonably familiar with the
9726 <prgn>dpkg
</prgn> System Administrators' manual.
9727 Unfortunately this manual does not yet exist.
9731 The Debian version of the FSF's GNU hello program is provided
9732 as an example for people wishing to create Debian
9733 packages. The Debian
<prgn>debmake
</prgn> package is
9734 recommended as a very helpful tool in creating and maintaining
9735 Debian packages. However, while the tools and examples are
9736 helpful, they do not replace the need to read and follow the
9737 Policy and Programmer's Manual.
</p>
9740 <appendix id=
"pkg-binarypkg">
9741 <heading>Binary packages (from old Packaging Manual)
</heading>
9744 The binary package has two main sections. The first part
9745 consists of various control information files and scripts used
9746 by
<prgn>dpkg
</prgn> when installing and removing. See
<ref
9747 id=
"pkg-controlarea">.
9751 The second part is an archive containing the files and
9752 directories to be installed.
9756 In the future binary packages may also contain other
9757 components, such as checksums and digital signatures. The
9758 format for the archive is described in full in the
9759 <file>deb(
5)
</file> man page.
9763 <sect id=
"pkg-bincreating"><heading>Creating package files -
9764 <prgn>dpkg-deb
</prgn>
9768 All manipulation of binary package files is done by
9769 <prgn>dpkg-deb
</prgn>; it's the only program that has
9770 knowledge of the format. (
<prgn>dpkg-deb
</prgn> may be
9771 invoked by calling
<prgn>dpkg
</prgn>, as
<prgn>dpkg
</prgn>
9772 will spot that the options requested are appropriate to
9773 <prgn>dpkg-deb
</prgn> and invoke that instead with the same
9778 In order to create a binary package you must make a
9779 directory tree which contains all the files and directories
9780 you want to have in the file system data part of the package.
9781 In Debian-format source packages this directory is usually
9782 <file>debian/tmp
</file>, relative to the top of the package's
9787 They should have the locations (relative to the root of the
9788 directory tree you're constructing) ownerships and
9789 permissions which you want them to have on the system when
9794 With current versions of
<prgn>dpkg
</prgn> the uid/username
9795 and gid/groupname mappings for the users and groups being
9796 used should be the same on the system where the package is
9797 built and the one where it is installed.
9801 You need to add one special directory to the root of the
9802 miniature file system tree you're creating:
9803 <prgn>DEBIAN
</prgn>. It should contain the control
9804 information files, notably the binary package control file
9805 (see
<ref id=
"pkg-controlfile">).
9809 The
<prgn>DEBIAN
</prgn> directory will not appear in the
9810 file system archive of the package, and so won't be installed
9811 by
<prgn>dpkg
</prgn> when the package is installed.
9815 When you've prepared the package, you should invoke:
9817 dpkg --build
<var>directory
</var>
9822 This will build the package in
9823 <file><var>directory
</var>.deb
</file>. (
<prgn>dpkg
</prgn> knows
9824 that
<tt>--build
</tt> is a
<prgn>dpkg-deb
</prgn> option, so
9825 it invokes
<prgn>dpkg-deb
</prgn> with the same arguments to
9830 See the man page
<manref name=
"dpkg-deb" section=
"8"> for details of how
9831 to examine the contents of this newly-created file. You may find the
9832 output of following commands enlightening:
9834 dpkg-deb --info
<var>filename
</var>.deb
9835 dpkg-deb --contents
<var>filename
</var>.deb
9836 dpkg --contents
<var>filename
</var>.deb
9838 To view the copyright file for a package you could use this command:
9840 dpkg --fsys-tarfile
<var>filename
</var>.deb | tar xOf - --wildcards \*/copyright | pager
9845 <sect id=
"pkg-controlarea">
9846 <heading>Package control information files
</heading>
9849 The control information portion of a binary package is a
9850 collection of files with names known to
<prgn>dpkg
</prgn>.
9851 It will treat the contents of these files specially - some
9852 of them contain information used by
<prgn>dpkg
</prgn> when
9853 installing or removing the package; others are scripts which
9854 the package maintainer wants
<prgn>dpkg
</prgn> to run.
9858 It is possible to put other files in the package control
9859 information file area, but this is not generally a good idea
9860 (though they will largely be ignored).
9864 Here is a brief list of the control information files supported
9865 by
<prgn>dpkg
</prgn> and a summary of what they're used for.
9870 <tag><tt>control
</tt>
9873 This is the key description file used by
9874 <prgn>dpkg
</prgn>. It specifies the package's name
9875 and version, gives its description for the user,
9876 states its relationships with other packages, and so
9877 forth. See
<ref id=
"sourcecontrolfiles"> and
9878 <ref id=
"binarycontrolfiles">.
9882 It is usually generated automatically from information
9883 in the source package by the
9884 <prgn>dpkg-gencontrol
</prgn> program, and with
9885 assistance from
<prgn>dpkg-shlibdeps
</prgn>.
9886 See
<ref id=
"pkg-sourcetools">.
9890 <tag><tt>postinst
</tt>,
<tt>preinst
</tt>,
<tt>postrm
</tt>,
9895 These are executable files (usually scripts) which
9896 <prgn>dpkg
</prgn> runs during installation, upgrade
9897 and removal of packages. They allow the package to
9898 deal with matters which are particular to that package
9899 or require more complicated processing than that
9900 provided by
<prgn>dpkg
</prgn>. Details of when and
9901 how they are called are in
<ref id=
"maintainerscripts">.
9905 It is very important to make these scripts idempotent.
9906 See
<ref id=
"idempotency">.
9910 The maintainer scripts are not guaranteed to run with a
9911 controlling terminal and may not be able to interact with
9912 the user. See
<ref id=
"controllingterminal">.
9916 <tag><tt>conffiles
</tt>
9919 This file contains a list of configuration files which
9920 are to be handled automatically by
<prgn>dpkg
</prgn>
9921 (see
<ref id=
"pkg-conffiles">). Note that not necessarily
9922 every configuration file should be listed here.
9925 <tag><tt>shlibs
</tt>
9928 This file contains a list of the shared libraries
9929 supplied by the package, with dependency details for
9930 each. This is used by
<prgn>dpkg-shlibdeps
</prgn>
9931 when it determines what dependencies are required in a
9932 package control file. The
<tt>shlibs
</tt> file format
9933 is described on
<ref id=
"shlibs">.
9938 <sect id=
"pkg-controlfile">
9939 <heading>The main control information file:
<tt>control
</tt></heading>
9942 The most important control information file used by
9943 <prgn>dpkg
</prgn> when it installs a package is
9944 <tt>control
</tt>. It contains all the package's
"vital
9949 The binary package control files of packages built from
9950 Debian sources are made by a special tool,
9951 <prgn>dpkg-gencontrol
</prgn>, which reads
9952 <file>debian/control
</file> and
<file>debian/changelog
</file> to
9953 find the information it needs. See
<ref id=
"pkg-sourcepkg"> for
9958 The fields in binary package control files are listed in
9959 <ref id=
"binarycontrolfiles">.
9963 A description of the syntax of control files and the purpose
9964 of the fields is available in
<ref id=
"controlfields">.
9969 <heading>Time Stamps
</heading>
9972 See
<ref id=
"timestamps">.
9977 <appendix id=
"pkg-sourcepkg">
9978 <heading>Source packages (from old Packaging Manual)
</heading>
9981 The Debian binary packages in the distribution are generated
9982 from Debian sources, which are in a special format to assist
9983 the easy and automatic building of binaries.
9986 <sect id=
"pkg-sourcetools">
9987 <heading>Tools for processing source packages
</heading>
9990 Various tools are provided for manipulating source packages;
9991 they pack and unpack sources and help build of binary
9992 packages and help manage the distribution of new versions.
9996 They are introduced and typical uses described here; see
9997 <manref name=
"dpkg-source" section=
"1"> for full
9998 documentation about their arguments and operation.
10002 For examples of how to construct a Debian source package,
10003 and how to use those utilities that are used by Debian
10004 source packages, please see the
<prgn>hello
</prgn> example
10008 <sect1 id=
"pkg-dpkg-source">
10010 <prgn>dpkg-source
</prgn> - packs and unpacks Debian source
10015 This program is frequently used by hand, and is also
10016 called from package-independent automated building scripts
10017 such as
<prgn>dpkg-buildpackage
</prgn>.
10021 To unpack a package it is typically invoked with
10023 dpkg-source -x
<var>.../path/to/filename
</var>.dsc
10028 with the
<file><var>filename
</var>.tar.gz
</file> and
10029 <file><var>filename
</var>.diff.gz
</file> (if applicable) in
10030 the same directory. It unpacks into
10031 <file><var>package
</var>-
<var>version
</var></file>, and if
10033 <file><var>package
</var>-
<var>version
</var>.orig
</file>, in
10034 the current directory.
10038 To create a packed source archive it is typically invoked:
10040 dpkg-source -b
<var>package
</var>-
<var>version
</var>
10045 This will create the
<file>.dsc
</file>,
<file>.tar.gz
</file> and
10046 <file>.diff.gz
</file> (if appropriate) in the current
10047 directory.
<prgn>dpkg-source
</prgn> does not clean the
10048 source tree first - this must be done separately if it is
10053 See also
<ref id=
"pkg-sourcearchives">.
</p>
10057 <sect1 id=
"pkg-dpkg-buildpackage">
10059 <prgn>dpkg-buildpackage
</prgn> - overall package-building
10064 <prgn>dpkg-buildpackage
</prgn> is a script which invokes
10065 <prgn>dpkg-source
</prgn>, the
<file>debian/rules
</file>
10066 targets
<tt>clean
</tt>,
<tt>build
</tt> and
10067 <tt>binary
</tt>,
<prgn>dpkg-genchanges
</prgn> and
10068 <prgn>gpg
</prgn> (or
<prgn>pgp
</prgn>) to build a signed
10069 source and binary package upload.
10073 It is usually invoked by hand from the top level of the
10074 built or unbuilt source directory. It may be invoked with
10075 no arguments; useful arguments include:
10076 <taglist compact=
"compact">
10077 <tag><tt>-uc
</tt>,
<tt>-us
</tt></tag>
10080 Do not sign the
<tt>.changes
</tt> file or the
10081 source package
<tt>.dsc
</tt> file, respectively.
</p>
10083 <tag><tt>-p
<var>sign-command
</var></tt></tag>
10086 Invoke
<var>sign-command
</var> instead of finding
10087 <tt>gpg
</tt> or
<tt>pgp
</tt> on the
<prgn>PATH
</prgn>.
10088 <var>sign-command
</var> must behave just like
10089 <prgn>gpg
</prgn> or
<tt>pgp
</tt>.
</p>
10091 <tag><tt>-r
<var>root-command
</var></tt></tag>
10094 When root privilege is required, invoke the command
10095 <var>root-command
</var>.
<var>root-command
</var>
10096 should invoke its first argument as a command, from
10097 the
<prgn>PATH
</prgn> if necessary, and pass its
10098 second and subsequent arguments to the command it
10099 calls. If no
<var>root-command
</var> is supplied
10100 then
<var>dpkg-buildpackage
</var> will take no
10101 special action to gain root privilege, so that for
10102 most packages it will have to be invoked as root to
10105 <tag><tt>-b
</tt>,
<tt>-B
</tt></tag>
10108 Two types of binary-only build and upload - see
10109 <manref name=
"dpkg-source" section=
"1">.
10116 <sect1 id=
"pkg-dpkg-gencontrol">
10118 <prgn>dpkg-gencontrol
</prgn> - generates binary package
10123 This program is usually called from
<file>debian/rules
</file>
10124 (see
<ref id=
"pkg-sourcetree">) in the top level of the source
10129 This is usually done just before the files and directories in the
10130 temporary directory tree where the package is being built have their
10131 permissions and ownerships set and the package is constructed using
10132 <prgn>dpkg-deb/
</prgn>
10134 This is so that the control file which is produced has
10135 the right permissions
10140 <prgn>dpkg-gencontrol
</prgn> must be called after all the
10141 files which are to go into the package have been placed in
10142 the temporary build directory, so that its calculation of
10143 the installed size of a package is correct.
10147 It is also necessary for
<prgn>dpkg-gencontrol
</prgn> to
10148 be run after
<prgn>dpkg-shlibdeps
</prgn> so that the
10149 variable substitutions created by
10150 <prgn>dpkg-shlibdeps
</prgn> in
<file>debian/substvars
</file>
10155 For a package which generates only one binary package, and
10156 which builds it in
<file>debian/tmp
</file> relative to the top
10157 of the source package, it is usually sufficient to call
10158 <prgn>dpkg-gencontrol
</prgn>.
10162 Sources which build several binaries will typically need
10165 dpkg-gencontrol -Pdebian/tmp-
<var>pkg
</var> -p
<var>package
</var>
10166 </example> The
<tt>-P
</tt> tells
10167 <prgn>dpkg-gencontrol
</prgn> that the package is being
10168 built in a non-default directory, and the
<tt>-p
</tt>
10169 tells it which package's control file should be generated.
10173 <prgn>dpkg-gencontrol
</prgn> also adds information to the
10174 list of files in
<file>debian/files
</file>, for the benefit of
10175 (for example) a future invocation of
10176 <prgn>dpkg-genchanges
</prgn>.
</p>
10179 <sect1 id=
"pkg-dpkg-shlibdeps">
10181 <prgn>dpkg-shlibdeps
</prgn> - calculates shared library
10186 This program is usually called from
<file>debian/rules
</file>
10187 just before
<prgn>dpkg-gencontrol
</prgn> (see
<ref
10188 id=
"pkg-sourcetree">), in the top level of the source tree.
10192 Its arguments are executables and shared libraries
10195 They may be specified either in the locations in the
10196 source tree where they are created or in the locations
10197 in the temporary build tree where they are installed
10198 prior to binary package creation.
10200 </footnote> for which shared library dependencies should
10201 be included in the binary package's control file.
10205 If some of the found shared libraries should only
10206 warrant a
<tt>Recommends
</tt> or
<tt>Suggests
</tt>, or if
10207 some warrant a
<tt>Pre-Depends
</tt>, this can be achieved
10208 by using the
<tt>-d
<var>dependency-field
</var></tt> option
10209 before those executable(s). (Each
<tt>-d
</tt> option
10210 takes effect until the next
<tt>-d
</tt>.)
10214 <prgn>dpkg-shlibdeps
</prgn> does not directly cause the
10215 output control file to be modified. Instead by default it
10216 adds to the
<file>debian/substvars
</file> file variable
10217 settings like
<tt>shlibs:Depends
</tt>. These variable
10218 settings must be referenced in dependency fields in the
10219 appropriate per-binary-package sections of the source
10224 For example, a package that generates an essential part
10225 which requires dependencies, and optional parts that
10226 which only require a recommendation, would separate those
10227 two sets of dependencies into two different fields.
<footnote>
10228 At the time of writing, an example for this was the
10229 <package/xmms/ package, with Depends used for the xmms
10230 executable, Recommends for the plug-ins and Suggests for
10231 even more optional features provided by unzip.
10233 It can say in its
<file>debian/rules
</file>:
10235 dpkg-shlibdeps -dDepends
<var>program anotherprogram ...
</var> \
10236 -dRecommends
<var>optionalpart anotheroptionalpart
</var>
10238 and then in its main control file
<file>debian/control
</file>:
10241 Depends: ${shlibs:Depends}
10242 Recommends: ${shlibs:Recommends}
10248 Sources which produce several binary packages with
10249 different shared library dependency requirements can use
10250 the
<tt>-p
<var>varnameprefix
</var></tt> option to override
10251 the default
<tt>shlibs:
</tt> prefix (one invocation of
10252 <prgn>dpkg-shlibdeps
</prgn> per setting of this option).
10253 They can thus produce several sets of dependency
10254 variables, each of the form
10255 <tt><var>varnameprefix
</var>:
<var>dependencyfield
</var></tt>,
10256 which can be referred to in the appropriate parts of the
10257 binary package control files.
10262 <sect1 id=
"pkg-dpkg-distaddfile">
10264 <prgn>dpkg-distaddfile
</prgn> - adds a file to
10265 <file>debian/files
</file>
10269 Some packages' uploads need to include files other than
10270 the source and binary package files.
10274 <prgn>dpkg-distaddfile
</prgn> adds a file to the
10275 <file>debian/files
</file> file so that it will be included in
10276 the
<file>.changes
</file> file when
10277 <prgn>dpkg-genchanges
</prgn> is run.
10281 It is usually invoked from the
<tt>binary
</tt> target of
10282 <file>debian/rules
</file>:
10284 dpkg-distaddfile
<var>filename
</var> <var>section
</var> <var>priority
</var>
10286 The
<var>filename
</var> is relative to the directory where
10287 <prgn>dpkg-genchanges
</prgn> will expect to find it - this
10288 is usually the directory above the top level of the source
10289 tree. The
<file>debian/rules
</file> target should put the
10290 file there just before or just after calling
10291 <prgn>dpkg-distaddfile
</prgn>.
10295 The
<var>section
</var> and
<var>priority
</var> are passed
10296 unchanged into the resulting
<file>.changes
</file> file.
10301 <sect1 id=
"pkg-dpkg-genchanges">
10303 <prgn>dpkg-genchanges
</prgn> - generates a
<file>.changes
</file>
10304 upload control file
10308 This program is usually called by package-independent
10309 automatic building scripts such as
10310 <prgn>dpkg-buildpackage
</prgn>, but it may also be called
10315 It is usually called in the top level of a built source
10316 tree, and when invoked with no arguments will print out a
10317 straightforward
<file>.changes
</file> file based on the
10318 information in the source package's changelog and control
10319 file and the binary and source packages which should have
10325 <sect1 id=
"pkg-dpkg-parsechangelog">
10327 <prgn>dpkg-parsechangelog
</prgn> - produces parsed
10328 representation of a changelog
10332 This program is used internally by
10333 <prgn>dpkg-source
</prgn> et al. It may also occasionally
10334 be useful in
<file>debian/rules
</file> and elsewhere. It
10335 parses a changelog,
<file>debian/changelog
</file> by default,
10336 and prints a control-file format representation of the
10337 information in it to standard output.
10341 <sect1 id=
"pkg-dpkg-architecture">
10343 <prgn>dpkg-architecture
</prgn> - information about the build and
10348 This program can be used manually, but is also invoked by
10349 <tt>dpkg-buildpackage
</tt> or
<file>debian/rules
</file> to set
10350 environment or make variables which specify the build and host
10351 architecture for the package building process.
10356 <sect id=
"pkg-sourcetree">
10357 <heading>The Debian package source tree
</heading>
10360 The source archive scheme described later is intended to
10361 allow a Debian package source tree with some associated
10362 control information to be reproduced and transported easily.
10363 The Debian package source tree is a version of the original
10364 program with certain files added for the benefit of the
10365 packaging process, and with any other changes required
10366 made to the rest of the source code and installation
10371 The extra files created for Debian are in the subdirectory
10372 <file>debian
</file> of the top level of the Debian package
10373 source tree. They are described below.
10376 <sect1 id=
"pkg-debianrules">
10377 <heading><file>debian/rules
</file> - the main building script
</heading>
10380 See
<ref id=
"debianrules">.
10384 <sect1 id=
"pkg-srcsubstvars">
10385 <heading><file>debian/substvars
</file> and variable substitutions
</heading>
10388 See
<ref id=
"substvars">.
10394 <heading><file>debian/files
</file></heading>
10397 See
<ref id=
"debianfiles">.
10401 <sect1><heading><file>debian/tmp
</file>
10405 This is the canonical temporary location for the
10406 construction of binary packages by the
<tt>binary
</tt>
10407 target. The directory
<file>tmp
</file> serves as the root of
10408 the file system tree as it is being constructed (for
10409 example, by using the package's upstream makefiles install
10410 targets and redirecting the output there), and it also
10411 contains the
<tt>DEBIAN
</tt> subdirectory. See
<ref
10412 id=
"pkg-bincreating">.
10416 If several binary packages are generated from the same
10417 source tree it is usual to use several
10418 <file>debian/tmp
<var>something
</var></file> directories, for
10419 example
<file>tmp-a
</file> or
<file>tmp-doc
</file>.
10423 Whatever
<file>tmp
</file> directories are created and used by
10424 <tt>binary
</tt> must of course be removed by the
10425 <tt>clean
</tt> target.
</p></sect1>
10429 <sect id=
"pkg-sourcearchives"><heading>Source packages as archives
10433 As it exists on the FTP site, a Debian source package
10434 consists of three related files. You must have the right
10435 versions of all three to be able to use them.
10440 <tag>Debian source control file -
<tt>.dsc
</tt></tag>
10442 This file is a control file used by
<prgn>dpkg-source
</prgn>
10443 to extract a source package.
10444 See
<ref id=
"debiansourcecontrolfiles">.
10448 Original source archive -
10450 <var>package
</var>_
<var>upstream-version
</var>.orig.tar.gz
10456 This is a compressed (with
<tt>gzip -
9</tt>)
10457 <prgn>tar
</prgn> file containing the source code from
10458 the upstream authors of the program.
10463 Debian package diff -
10465 <var>package
</var>_
<var>upstream_version-revision
</var>.diff.gz
10471 This is a unified context diff (
<tt>diff -u
</tt>)
10472 giving the changes which are required to turn the
10473 original source into the Debian source. These changes
10474 may only include editing and creating plain files.
10475 The permissions of files, the targets of symbolic
10476 links and the characteristics of special files or
10477 pipes may not be changed and no files may be removed
10482 All the directories in the diff must exist, except the
10483 <file>debian
</file> subdirectory of the top of the source
10484 tree, which will be created by
10485 <prgn>dpkg-source
</prgn> if necessary when unpacking.
10489 The
<prgn>dpkg-source
</prgn> program will
10490 automatically make the
<file>debian/rules
</file> file
10491 executable (see below).
</p></item>
10496 If there is no original source code - for example, if the
10497 package is specially prepared for Debian or the Debian
10498 maintainer is the same as the upstream maintainer - the
10499 format is slightly different: then there is no diff, and the
10501 <file><var>package
</var>_
<var>version
</var>.tar.gz
</file>,
10502 and preferably contains a directory named
10503 <file><var>package
</var>-
<var>version
</var></file>.
10508 <heading>Unpacking a Debian source package without
<prgn>dpkg-source
</prgn></heading>
10511 <tt>dpkg-source -x
</tt> is the recommended way to unpack a
10512 Debian source package. However, if it is not available it
10513 is possible to unpack a Debian source archive as follows:
10514 <enumlist compact=
"compact">
10517 Untar the tarfile, which will create a
<file>.orig
</file>
10521 <p>Rename the
<file>.orig
</file> directory to
10522 <file><var>package
</var>-
<var>version
</var></file>.
</p>
10526 Create the subdirectory
<file>debian
</file> at the top of
10527 the source tree.
</p>
10529 <item><p>Apply the diff using
<tt>patch -p0
</tt>.
</p>
10531 <item><p>Untar the tarfile again if you want a copy of the original
10532 source code alongside the Debian version.
</p>
10537 It is not possible to generate a valid Debian source archive
10538 without using
<prgn>dpkg-source
</prgn>. In particular,
10539 attempting to use
<prgn>diff
</prgn> directly to generate the
10540 <file>.diff.gz
</file> file will not work.
10544 <heading>Restrictions on objects in source packages
</heading>
10547 The source package may not contain any hard links
10549 This is not currently detected when building source
10550 packages, but only when extracting
10554 Hard links may be permitted at some point in the
10555 future, but would require a fair amount of
10557 </footnote>, device special files, sockets or setuid or
10560 Setgid directories are allowed.
10565 The source packaging tools manage the changes between the
10566 original and Debian source using
<prgn>diff
</prgn> and
10567 <prgn>patch
</prgn>. Turning the original source tree as
10568 included in the
<file>.orig.tar.gz
</file> into the Debian
10569 package source must not involve any changes which cannot be
10570 handled by these tools. Problematic changes which cause
10571 <prgn>dpkg-source
</prgn> to halt with an error when
10572 building the source package are:
10573 <list compact=
"compact">
10574 <item><p>Adding or removing symbolic links, sockets or pipes.
</p>
10576 <item><p>Changing the targets of symbolic links.
</p>
10578 <item><p>Creating directories, other than
<file>debian
</file>.
</p>
10580 <item><p>Changes to the contents of binary files.
</p></item>
10581 </list> Changes which cause
<prgn>dpkg-source
</prgn> to
10582 print a warning but continue anyway are:
10583 <list compact=
"compact">
10586 Removing files, directories or symlinks.
10588 Renaming a file is not treated specially - it is
10589 seen as the removal of the old file (which
10590 generates a warning, but is otherwise ignored),
10591 and the creation of the new one.
10597 Changed text files which are missing the usual final
10598 newline (either in the original or the modified
10603 Changes which are not represented, but which are not detected by
10604 <prgn>dpkg-source
</prgn>, are:
10605 <list compact=
"compact">
10606 <item><p>Changing the permissions of files (other than
10607 <file>debian/rules
</file>) and directories.
</p></item>
10612 The
<file>debian
</file> directory and
<file>debian/rules
</file>
10613 are handled specially by
<prgn>dpkg-source
</prgn> - before
10614 applying the changes it will create the
<file>debian
</file>
10615 directory, and afterwards it will make
10616 <file>debian/rules
</file> world-executable.
10622 <appendix id=
"pkg-controlfields">
10623 <heading>Control files and their fields (from old Packaging Manual)
</heading>
10626 Many of the tools in the
<prgn>dpkg
</prgn> suite manipulate
10627 data in a common format, known as control files. Binary and
10628 source packages have control data as do the
<file>.changes
</file>
10629 files which control the installation of uploaded files, and
10630 <prgn>dpkg
</prgn>'s internal databases are in a similar
10635 <heading>Syntax of control files
</heading>
10638 See
<ref id=
"controlsyntax">.
10642 It is important to note that there are several fields which
10643 are optional as far as
<prgn>dpkg
</prgn> and the related
10644 tools are concerned, but which must appear in every Debian
10645 package, or whose omission may cause problems.
10650 <heading>List of fields
</heading>
10653 See
<ref id=
"controlfieldslist">.
10657 This section now contains only the fields that didn't belong
10658 to the Policy manual.
10661 <sect1 id=
"pkg-f-Filename">
10662 <heading><tt>Filename
</tt> and
<tt>MSDOS-Filename
</tt></heading>
10665 These fields in
<tt>Packages
</tt> files give the
10666 filename(s) of (the parts of) a package in the
10667 distribution directories, relative to the root of the
10668 Debian hierarchy. If the package has been split into
10669 several parts the parts are all listed in order, separated
10674 <sect1 id=
"pkg-f-Size">
10675 <heading><tt>Size
</tt> and
<tt>MD5sum
</tt></heading>
10678 These fields in
<file>Packages
</file> files give the size (in
10679 bytes, expressed in decimal) and MD5 checksum of the
10680 file(s) which make(s) up a binary package in the
10681 distribution. If the package is split into several parts
10682 the values for the parts are listed in order, separated by
10687 <sect1 id=
"pkg-f-Status">
10688 <heading><tt>Status
</tt></heading>
10691 This field in
<prgn>dpkg
</prgn>'s status file records
10692 whether the user wants a package installed, removed or
10693 left alone, whether it is broken (requiring
10694 re-installation) or not and what its current state on the
10695 system is. Each of these pieces of information is a
10700 <sect1 id=
"pkg-f-Config-Version">
10701 <heading><tt>Config-Version
</tt></heading>
10704 If a package is not installed or not configured, this
10705 field in
<prgn>dpkg
</prgn>'s status file records the last
10706 version of the package which was successfully
10711 <sect1 id=
"pkg-f-Conffiles">
10712 <heading><tt>Conffiles
</tt></heading>
10715 This field in
<prgn>dpkg
</prgn>'s status file contains
10716 information about the automatically-managed configuration
10717 files held by a package. This field should
<em>not
</em>
10718 appear anywhere in a package!
10723 <heading>Obsolete fields
</heading>
10726 These are still recognized by
<prgn>dpkg
</prgn> but should
10727 not appear anywhere any more.
10729 <taglist compact=
"compact">
10731 <tag><tt>Revision
</tt></tag>
10732 <tag><tt>Package-Revision
</tt></tag>
10733 <tag><tt>Package_Revision
</tt></tag>
10735 The Debian revision part of the package version was
10736 at one point in a separate control field. This
10737 field went through several names.
10740 <tag><tt>Recommended
</tt></tag>
10741 <item>Old name for
<tt>Recommends
</tt>.
</item>
10743 <tag><tt>Optional
</tt></tag>
10744 <item>Old name for
<tt>Suggests
</tt>.
</item>
10746 <tag><tt>Class
</tt></tag>
10747 <item>Old name for
<tt>Priority
</tt>.
</item>
10756 <appendix id=
"pkg-conffiles">
10757 <heading>Configuration file handling (from old Packaging Manual)
</heading>
10760 <prgn>dpkg
</prgn> can do a certain amount of automatic
10761 handling of package configuration files.
10765 Whether this mechanism is appropriate depends on a number of
10766 factors, but basically there are two approaches to any
10767 particular configuration file.
10771 The easy method is to ship a best-effort configuration in the
10772 package, and use
<prgn>dpkg
</prgn>'s conffile mechanism to
10773 handle updates. If the user is unlikely to want to edit the
10774 file, but you need them to be able to without losing their
10775 changes, and a new package with a changed version of the file
10776 is only released infrequently, this is a good approach.
10780 The hard method is to build the configuration file from
10781 scratch in the
<prgn>postinst
</prgn> script, and to take the
10782 responsibility for fixing any mistakes made in earlier
10783 versions of the package automatically. This will be
10784 appropriate if the file is likely to need to be different on
10788 <sect><heading>Automatic handling of configuration files by
10793 A package may contain a control information file called
10794 <tt>conffiles
</tt>. This file should be a list of filenames
10795 of configuration files needing automatic handling, separated
10796 by newlines. The filenames should be absolute pathnames,
10797 and the files referred to should actually exist in the
10802 When a package is upgraded
<prgn>dpkg
</prgn> will process
10803 the configuration files during the configuration stage,
10804 shortly before it runs the package's
<prgn>postinst
</prgn>
10809 For each file it checks to see whether the version of the
10810 file included in the package is the same as the one that was
10811 included in the last version of the package (the one that is
10812 being upgraded from); it also compares the version currently
10813 installed on the system with the one shipped with the last
10818 If neither the user nor the package maintainer has changed
10819 the file, it is left alone. If one or the other has changed
10820 their version, then the changed version is preferred - i.e.,
10821 if the user edits their file, but the package maintainer
10822 doesn't ship a different version, the user's changes will
10823 stay, silently, but if the maintainer ships a new version
10824 and the user hasn't edited it the new version will be
10825 installed (with an informative message). If both have
10826 changed their version the user is prompted about the problem
10827 and must resolve the differences themselves.
10831 The comparisons are done by calculating the MD5 message
10832 digests of the files, and storing the MD5 of the file as it
10833 was included in the most recent version of the package.
10837 When a package is installed for the first time
10838 <prgn>dpkg
</prgn> will install the file that comes with it,
10839 unless that would mean overwriting a file already on the
10844 However, note that
<prgn>dpkg
</prgn> will
<em>not
</em>
10845 replace a conffile that was removed by the user (or by a
10846 script). This is necessary because with some programs a
10847 missing file produces an effect hard or impossible to
10848 achieve in another way, so that a missing file needs to be
10849 kept that way if the user did it.
10853 Note that a package should
<em>not
</em> modify a
10854 <prgn>dpkg
</prgn>-handled conffile in its maintainer
10855 scripts. Doing this will lead to
<prgn>dpkg
</prgn> giving
10856 the user confusing and possibly dangerous options for
10857 conffile update when the package is upgraded.
</p>
10860 <sect><heading>Fully-featured maintainer script configuration
10865 For files which contain site-specific information such as
10866 the hostname and networking details and so forth, it is
10867 better to create the file in the package's
10868 <prgn>postinst
</prgn> script.
10872 This will typically involve examining the state of the rest
10873 of the system to determine values and other information, and
10874 may involve prompting the user for some information which
10875 can't be obtained some other way.
10879 When using this method there are a couple of important
10880 issues which should be considered:
10884 If you discover a bug in the program which generates the
10885 configuration file, or if the format of the file changes
10886 from one version to the next, you will have to arrange for
10887 the postinst script to do something sensible - usually this
10888 will mean editing the installed configuration file to remove
10889 the problem or change the syntax. You will have to do this
10890 very carefully, since the user may have changed the file,
10891 perhaps to fix the very problem that your script is trying
10892 to deal with - you will have to detect these situations and
10893 deal with them correctly.
10897 If you do go down this route it's probably a good idea to
10898 make the program that generates the configuration file(s) a
10899 separate program in
<file>/usr/sbin
</file>, by convention called
10900 <file><var>package
</var>config
</file> and then run that if
10901 appropriate from the post-installation script. The
10902 <tt><var>package
</var>config
</tt> program should not
10903 unquestioningly overwrite an existing configuration - if its
10904 mode of operation is geared towards setting up a package for
10905 the first time (rather than any arbitrary reconfiguration
10906 later) you should have it check whether the configuration
10907 already exists, and require a
<tt>--force
</tt> flag to
10908 overwrite it.
</p></sect>
10911 <appendix id=
"pkg-alternatives"><heading>Alternative versions of
10912 an interface -
<prgn>update-alternatives
</prgn> (from old
10917 When several packages all provide different versions of the
10918 same program or file it is useful to have the system select a
10919 default, but to allow the system administrator to change it
10920 and have their decisions respected.
10924 For example, there are several versions of the
<prgn>vi
</prgn>
10925 editor, and there is no reason to prevent all of them from
10926 being installed at once, each under their own name
10927 (
<prgn>nvi
</prgn>,
<prgn>vim
</prgn> or whatever).
10928 Nevertheless it is desirable to have the name
<tt>vi
</tt>
10929 refer to something, at least by default.
10933 If all the packages involved cooperate, this can be done with
10934 <prgn>update-alternatives
</prgn>.
10938 Each package provides its own version under its own name, and
10939 calls
<prgn>update-alternatives
</prgn> in its postinst to
10940 register its version (and again in its prerm to deregister
10945 See the man page
<manref name=
"update-alternatives"
10946 section=
"8"> for details.
10950 If
<prgn>update-alternatives
</prgn> does not seem appropriate
10951 you may wish to consider using diversions instead.
</p>
10954 <appendix id=
"pkg-diversions"><heading>Diversions - overriding a
10955 package's version of a file (from old Packaging Manual)
10959 It is possible to have
<prgn>dpkg
</prgn> not overwrite a file
10960 when it reinstalls the package it belongs to, and to have it
10961 put the file from the package somewhere else instead.
10965 This can be used locally to override a package's version of a
10966 file, or by one package to override another's version (or
10967 provide a wrapper for it).
10971 Before deciding to use a diversion, read
<ref
10972 id=
"pkg-alternatives"> to see if you really want a diversion
10973 rather than several alternative versions of a program.
10977 There is a diversion list, which is read by
<prgn>dpkg
</prgn>,
10978 and updated by a special program
<prgn>dpkg-divert
</prgn>.
10979 Please see
<manref name=
"dpkg-divert" section=
"8"> for full
10980 details of its operation.
10984 When a package wishes to divert a file from another, it should
10985 call
<prgn>dpkg-divert
</prgn> in its preinst to add the
10986 diversion and rename the existing file. For example,
10987 supposing that a
<prgn>smailwrapper
</prgn> package wishes to
10988 install a wrapper around
<file>/usr/sbin/smail
</file>:
10990 dpkg-divert --package smailwrapper --add --rename \
10991 --divert /usr/sbin/smail.real /usr/sbin/smail
10992 </example> The
<tt>--package smailwrapper
</tt> ensures that
10993 <prgn>smailwrapper
</prgn>'s copy of
<file>/usr/sbin/smail
</file>
10994 can bypass the diversion and get installed as the true version.
10995 It's safe to add the diversion unconditionally on upgrades since
10996 it will be left unchanged if it already exists, but
10997 <prgn>dpkg-divert
</prgn> will display a message. To suppress that
10998 message, make the command conditional on the version from which
10999 the package is being upgraded:
11001 if [ upgrade !=
"$1" ] || dpkg --compare-versions
"$2" lt
1.0-
2; then
11002 dpkg-divert --package smailwrapper --add --rename \
11003 --divert /usr/sbin/smail.real /usr/sbin/smail
11005 </example> where
<tt>1.0-
2</tt> is the version at which the
11006 diversion was first added to the package. Running the command
11007 during abort-upgrade is pointless but harmless.
11011 The postrm has to do the reverse:
11013 if [ remove =
"$1" -o abort-install =
"$1" -o disappear =
"$1" ]; then
11014 dpkg-divert --package smailwrapper --remove --rename \
11015 --divert /usr/sbin/smail.real /usr/sbin/smail
11017 </example> If the diversion was added at a particular version, the
11018 postrm should also handle the failure case of upgrading from an
11019 older version (unless the older version is so old that direct
11020 upgrades are no longer supported):
11022 if [ abort-upgrade =
"$1" ] && dpkg --compare-versions
"$2" lt
1.0-
2; then
11023 dpkg-divert --package smailwrapper --remove --rename \
11024 --divert /usr/sbin/smail.real /usr/sbin/smail
11026 </example> where
<tt>1.02-
2</tt> is the version at which the
11027 diversion was first added to the package. The postrm should not
11028 remove the diversion on upgrades both because there's no reason to
11029 remove the diversion only to immediately re-add it and since the
11030 postrm of the old package is run after unpacking so the removal of
11031 the diversion will fail.
11035 Do not attempt to divert a file which is vitally important for
11036 the system's operation - when using
<prgn>dpkg-divert
</prgn>
11037 there is a time, after it has been diverted but before
11038 <prgn>dpkg
</prgn> has installed the new version, when the file
11039 does not exist.
</p>
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