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;
10 <title>Debian Policy Manual
</title>
11 <author><qref id=
"authors">The Debian Policy Mailing List
</qref></author>
12 <version>version
&version;,
&date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright
© 1996,
1997,
1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty
</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL
</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id=
"http://www.gnu.org/copyleft/gpl.html"
47 name=
"the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 51 Franklin St, Fifth Floor, Boston, MA
02110-
1301, USA.
57 <heading>About this manual
</heading>
59 <heading>Scope
</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.
<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact=
"compact">
79 <tag>Standard interfaces
</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention
</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see
<ref id=
"pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words
<em>must
</em>,
<em>should
</em> and
119 <em>may
</em>, and the adjectives
<em>required
</em>,
120 <em>recommended
</em> and
<em>optional
</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by
<em>must
</em> (or
<em>required
</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should
</em> (or
<em>recommended
</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may
</em> (or
<em>optional
</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities
<em>serious
</em> (for
<em>must
</em> or
136 <em>required
</em> directive violations),
<em>minor
</em>,
137 <em>normal
</em> or
<em>important
</em>
138 (for
<em>should
</em> or
<em>recommended
</em> directive
139 violations) and
<em>wishlist
</em> (for
<em>optional
</em>
142 Compare RFC
2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document
</heading>
159 This manual is distributed via the Debian package
160 <package><url name=
"debian-policy"
161 id=
"http://packages.debian.org/debian-policy"></package>
162 (
<httpsite>packages.debian.org
</httpsite>
163 <httppath>/debian-policy
</httppath>).
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name=
"/doc/debian-policy/"
170 id=
"http://www.debian.org/doc/debian-policy/"></tt>.
172 <httpsite>www.debian.org
</httpsite>
173 <httppath>/doc/debian-policy/
</httppath>)
174 Also available from the same directory are several other
175 formats:
<file>policy.html.tar.gz
</file>
176 (
<httppath>/doc/debian-policy/policy.html.tar.gz
</httppath>),
177 <file>policy.pdf.gz
</file>
178 (
<httppath>/doc/debian-policy/policy.pdf.gz
</httppath>)
179 and
<file>policy.ps.gz
</file>
180 (
<httppath>/doc/debian-policy/policy.ps.gz
</httppath>).
184 The
<package>debian-policy
</package> package also includes the file
185 <file>upgrading-checklist.txt.gz
</file> which indicates policy
186 changes between versions of this document.
191 <heading>Authors and Maintainers
</heading>
194 Originally called
"Debian GNU/Linux Policy Manual", this
195 manual was initially written in
1996 by Ian Jackson.
196 It was revised on November
27th,
1996 by David A. Morris.
197 Christian Schwarz added new sections on March
15th,
1997,
198 and reworked/restructured it in April-July
1997.
199 Christoph Lameter contributed the
"Web Standard".
200 Julian Gilbey largely restructured it in
2001.
204 Since September
1998, the responsibility for the contents of
205 this document lies on the
<url name=
"debian-policy mailing list"
206 id=
"mailto:debian-policy@lists.debian.org">. Proposals
207 are discussed there and inserted into policy after a certain
208 consensus is established.
209 <!-- insert shameless policy-process plug here eventually -->
210 The actual editing is done by a group of maintainers that have
211 no editorial powers. These are the current maintainers:
214 <item>Julian Gilbey
</item>
215 <item>Branden Robinson
</item>
216 <item>Josip Rodin
</item>
217 <item>Manoj Srivastava
</item>
222 While the authors of this document have tried hard to avoid
223 typos and other errors, these do still occur. If you discover
224 an error in this manual or if you want to give any
225 comments, suggestions, or criticisms please send an email to
226 the Debian Policy List,
227 <email>debian-policy@lists.debian.org
</email>, or submit a
228 bug report against the
<tt>debian-policy
</tt> package.
232 Please do not try to reach the individual authors or maintainers
233 of the Policy Manual regarding changes to the Policy.
238 <heading>Related documents
</heading>
241 There are several other documents other than this Policy Manual
242 that are necessary to fully understand some Debian policies and
247 The external
"sub-policy" documents are referred to in:
248 <list compact=
"compact">
249 <item><ref id=
"fhs"></item>
250 <item><ref id=
"virtual_pkg"></item>
251 <item><ref id=
"menus"></item>
252 <item><ref id=
"mime"></item>
253 <item><ref id=
"perl"></item>
254 <item><ref id=
"maintscriptprompt"></item>
255 <item><ref id=
"emacs"></item>
260 In addition to those, which carry the weight of policy, there
261 is the Debian Developer's Reference. This document describes
262 procedures and resources for Debian developers, but it is
263 <em>not
</em> normative; rather, it includes things that don't
264 belong in the Policy, such as best practices for developers.
268 The Developer's Reference is available in the
269 <package>developers-reference
</package> package.
270 It's also available from the Debian web mirrors at
271 <tt><url name=
"/doc/developers-reference/"
272 id=
"http://www.debian.org/doc/developers-reference/"></tt>.
276 <sect id=
"definitions">
277 <heading>Definitions
</heading>
280 The following terms are used in this Policy Manual:
284 The character encoding specified by ANSI X3.4-
1986 and its
285 predecessor standards, referred to in MIME as US-ASCII, and
286 corresponding to an encoding in eight bits per character of
287 the first
128 <url id=
"http://www.unicode.org/"
288 name=
"Unicode"> characters, with the eighth bit always zero.
292 The transformation format (sometimes called encoding) of
293 <url id=
"http://www.unicode.org/" name=
"Unicode"> defined by
294 <url id=
"http://www.rfc-editor.org/rfc/rfc3629.txt"
295 name=
"RFC 3629">. UTF-
8 has the useful property of having
296 ASCII as a subset, so any text encoded in ASCII is trivially
306 <heading>The Debian Archive
</heading>
309 The Debian GNU/Linux system is maintained and distributed as a
310 collection of
<em>packages
</em>. Since there are so many of
311 them (currently well over
15000), they are split into
312 <em>sections
</em> and given
<em>priorities
</em> to simplify
313 the handling of them.
317 The effort of the Debian project is to build a free operating
318 system, but not every package we want to make accessible is
319 <em>free
</em> in our sense (see the Debian Free Software
320 Guidelines, below), or may be imported/exported without
321 restrictions. Thus, the archive is split into areas
<footnote>
322 The Debian archive software uses the term
"component" internally
323 and in the Release file format to refer to the division of an
324 archive. The Debian Social Contract simply refers to
"areas."
325 This document uses terminology similar to the Social Contract.
326 </footnote> based on their licenses and other restrictions.
330 The aims of this are:
332 <list compact=
"compact">
333 <item>to allow us to make as much software available as we can
</item>
334 <item>to allow us to encourage everyone to write free software,
336 <item>to allow us to make it easy for people to produce
337 CD-ROMs of our system without violating any licenses,
338 import/export restrictions, or any other laws.
</item>
343 The
<em>main
</em> archive area forms the
<em>Debian GNU/Linux
348 Packages in the other archive areas (
<tt>contrib
</tt>,
349 <tt>non-free
</tt>) are not considered to be part of the Debian
350 distribution, although we support their use and provide
351 infrastructure for them (such as our bug-tracking system and
352 mailing lists). This Debian Policy Manual applies to these
357 <heading>The Debian Free Software Guidelines
</heading>
359 The Debian Free Software Guidelines (DFSG) form our
360 definition of
"free software". These are:
362 <tag>Free Redistribution
365 The license of a Debian component may not restrict any
366 party from selling or giving away the software as a
367 component of an aggregate software distribution
368 containing programs from several different
369 sources. The license may not require a royalty or
370 other fee for such sale.
375 The program must include source code, and must allow
376 distribution in source code as well as compiled form.
381 The license must allow modifications and derived
382 works, and must allow them to be distributed under the
383 same terms as the license of the original software.
385 <tag>Integrity of The Author's Source Code
388 The license may restrict source-code from being
389 distributed in modified form
<em>only
</em> if the
390 license allows the distribution of
"patch files"
391 with the source code for the purpose of modifying the
392 program at build time. The license must explicitly
393 permit distribution of software built from modified
394 source code. The license may require derived works to
395 carry a different name or version number from the
396 original software. (This is a compromise. The Debian
397 Project encourages all authors to not restrict any
398 files, source or binary, from being modified.)
400 <tag>No Discrimination Against Persons or Groups
403 The license must not discriminate against any person
406 <tag>No Discrimination Against Fields of Endeavor
409 The license must not restrict anyone from making use
410 of the program in a specific field of endeavor. For
411 example, it may not restrict the program from being
412 used in a business, or from being used for genetic
415 <tag>Distribution of License
418 The rights attached to the program must apply to all
419 to whom the program is redistributed without the need
420 for execution of an additional license by those
423 <tag>License Must Not Be Specific to Debian
426 The rights attached to the program must not depend on
427 the program's being part of a Debian system. If the
428 program is extracted from Debian and used or
429 distributed without Debian but otherwise within the
430 terms of the program's license, all parties to whom
431 the program is redistributed must have the same
432 rights as those that are granted in conjunction with
435 <tag>License Must Not Contaminate Other Software
438 The license must not place restrictions on other
439 software that is distributed along with the licensed
440 software. For example, the license must not insist
441 that all other programs distributed on the same medium
442 must be free software.
444 <tag>Example Licenses
447 The
"GPL," "BSD," and
"Artistic" licenses are examples of
448 licenses that we consider
<em>free
</em>.
455 <heading>Archive areas
</heading>
458 <heading>The main archive area
</heading>
461 Every package in
<em>main
</em> must comply with the DFSG
462 (Debian Free Software Guidelines).
466 In addition, the packages in
<em>main
</em>
467 <list compact=
"compact">
469 must not require a package outside of
<em>main
</em>
470 for compilation or execution (thus, the package must
471 not declare a
"Depends",
"Recommends", or
472 "Build-Depends" relationship on a non-
<em>main
</em>
476 must not be so buggy that we refuse to support them,
480 must meet all policy requirements presented in this
489 <heading>The contrib archive area
</heading>
492 Every package in
<em>contrib
</em> must comply with the DFSG.
496 In addition, the packages in
<em>contrib
</em>
497 <list compact=
"compact">
499 must not be so buggy that we refuse to support them,
503 must meet all policy requirements presented in this
511 Examples of packages which would be included in
512 <em>contrib
</em> are:
513 <list compact=
"compact">
515 free packages which require
<em>contrib
</em>,
516 <em>non-free
</em> packages or packages which are not
517 in our archive at all for compilation or execution,
521 wrapper packages or other sorts of free accessories for
528 <sect1 id=
"non-free">
529 <heading>The non-free archive area
</heading>
532 Packages must be placed in
<em>non-free
</em> if they are
533 not compliant with the DFSG or are encumbered by patents
534 or other legal issues that make their distribution
539 In addition, the packages in
<em>non-free
</em>
540 <list compact=
"compact">
542 must not be so buggy that we refuse to support them,
546 must meet all policy requirements presented in this
547 manual that it is possible for them to meet.
549 It is possible that there are policy
550 requirements which the package is unable to
551 meet, for example, if the source is
552 unavailable. These situations will need to be
553 handled on a case-by-case basis.
562 <sect id=
"pkgcopyright">
563 <heading>Copyright considerations
</heading>
566 Every package must be accompanied by a verbatim copy of
567 its copyright and distribution license in the file
568 <file>/usr/share/doc/
<var>package
</var>/copyright
</file>
569 (see
<ref id=
"copyrightfile"> for further details).
573 We reserve the right to restrict files from being included
574 anywhere in our archives if
575 <list compact=
"compact">
577 their use or distribution would break a law,
580 there is an ethical conflict in their distribution or
584 we would have to sign a license for them, or
587 their distribution would conflict with other project
594 Programs whose authors encourage the user to make
595 donations are fine for the main distribution, provided
596 that the authors do not claim that not donating is
597 immoral, unethical, illegal or something similar; in such
598 a case they must go in
<em>non-free
</em>.
602 Packages whose copyright permission notices (or patent
603 problems) do not even allow redistribution of binaries
604 only, and where no special permission has been obtained,
605 must not be placed on the Debian FTP site and its mirrors
610 Note that under international copyright law (this applies
611 in the United States, too),
<em>no
</em> distribution or
612 modification of a work is allowed without an explicit
613 notice saying so. Therefore a program without a copyright
614 notice
<em>is
</em> copyrighted and you may not do anything
615 to it without risking being sued! Likewise if a program
616 has a copyright notice but no statement saying what is
617 permitted then nothing is permitted.
621 Many authors are unaware of the problems that restrictive
622 copyrights (or lack of copyright notices) can cause for
623 the users of their supposedly-free software. It is often
624 worthwhile contacting such authors diplomatically to ask
625 them to modify their license terms. However, this can be a
626 politically difficult thing to do and you should ask for
627 advice on the
<tt>debian-legal
</tt> mailing list first, as
632 When in doubt about a copyright, send mail to
633 <email>debian-legal@lists.debian.org
</email>. Be prepared
634 to provide us with the copyright statement. Software
635 covered by the GPL, public domain software and BSD-like
636 copyrights are safe; be wary of the phrases
"commercial
637 use prohibited" and
"distribution restricted".
641 <sect id=
"subsections">
642 <heading>Sections
</heading>
645 The packages in the archive areas
<em>main
</em>,
646 <em>contrib
</em> and
<em>non-free
</em> are grouped further into
647 <em>sections
</em> to simplify handling.
651 The archive area and section for each package should be
652 specified in the package's
<tt>Section
</tt> control record (see
653 <ref id=
"f-Section">). However, the maintainer of the Debian
654 archive may override this selection to ensure the consistency of
655 the Debian distribution. The
<tt>Section
</tt> field should be
657 <list compact=
"compact">
659 <em>section
</em> if the package is in the
660 <em>main
</em> archive area,
663 <em>area/section
</em> if the package is in
664 the
<em>contrib
</em> or
<em>non-free
</em>
671 The Debian archive maintainers provide the authoritative
672 list of sections. At present, they are:
673 <em>admin
</em>,
<em>cli-mono
</em>,
<em>comm
</em>,
<em>database
</em>,
674 <em>devel
</em>,
<em>debug
</em>,
<em>doc
</em>,
<em>editors
</em>,
675 <em>electronics
</em>,
<em>embedded
</em>,
<em>fonts
</em>,
676 <em>games
</em>,
<em>gnome
</em>,
<em>graphics
</em>,
<em>gnu-r
</em>,
677 <em>gnustep
</em>,
<em>hamradio
</em>,
<em>haskell
</em>,
678 <em>httpd
</em>,
<em>interpreters
</em>,
<em>java
</em>,
<em>kde
</em>,
679 <em>kernel
</em>,
<em>libs
</em>,
<em>libdevel
</em>,
<em>lisp
</em>,
680 <em>localization
</em>,
<em>mail
</em>,
<em>math
</em>,
<em>misc
</em>,
681 <em>net
</em>,
<em>news
</em>,
<em>ocaml
</em>,
<em>oldlibs
</em>,
682 <em>otherosfs
</em>,
<em>perl
</em>,
<em>php
</em>,
<em>python
</em>,
683 <em>ruby
</em>,
<em>science
</em>,
<em>shells
</em>,
<em>sound
</em>,
684 <em>tex
</em>,
<em>text
</em>,
<em>utils
</em>,
<em>vcs
</em>,
685 <em>video
</em>,
<em>web
</em>,
<em>x11
</em>,
<em>xfce
</em>,
690 <sect id=
"priorities">
691 <heading>Priorities
</heading>
694 Each package should have a
<em>priority
</em> value, which is
695 included in the package's
<em>control record
</em>
696 (see
<ref id=
"f-Priority">).
697 This information is used by the Debian package management tools to
698 separate high-priority packages from less-important packages.
702 The following
<em>priority levels
</em> are recognized by the
703 Debian package management tools.
705 <tag><tt>required
</tt></tag>
707 Packages which are necessary for the proper
708 functioning of the system (usually, this means that
709 dpkg functionality depends on these packages).
710 Removing a
<tt>required
</tt> package may cause your
711 system to become totally broken and you may not even
712 be able to use
<prgn>dpkg
</prgn> to put things back,
713 so only do so if you know what you are doing. Systems
714 with only the
<tt>required
</tt> packages are probably
715 unusable, but they do have enough functionality to
716 allow the sysadmin to boot and install more software.
718 <tag><tt>important
</tt></tag>
720 Important programs, including those which one would
721 expect to find on any Unix-like system. If the
722 expectation is that an experienced Unix person who
723 found it missing would say
"What on earth is going on,
724 where is <prgn>foo</prgn>?", it must be an
725 <tt>important
</tt> package.
<footnote>
726 This is an important criterion because we are
727 trying to produce, amongst other things, a free
730 Other packages without which the system will not run
731 well or be usable must also have priority
732 <tt>important
</tt>. This does
733 <em>not
</em> include Emacs, the X Window System, TeX
734 or any other large applications. The
735 <tt>important
</tt> packages are just a bare minimum of
736 commonly-expected and necessary tools.
738 <tag><tt>standard
</tt></tag>
740 These packages provide a reasonably small but not too
741 limited character-mode system. This is what will be
742 installed by default if the user doesn't select anything
743 else. It doesn't include many large applications.
745 <tag><tt>optional
</tt></tag>
747 (In a sense everything that isn't required is
748 optional, but that's not what is meant here.) This is
749 all the software that you might reasonably want to
750 install if you didn't know what it was and don't have
751 specialized requirements. This is a much larger system
752 and includes the X Window System, a full TeX
753 distribution, and many applications. Note that
754 optional packages should not conflict with each other.
756 <tag><tt>extra
</tt></tag>
758 This contains all packages that conflict with others
759 with required, important, standard or optional
760 priorities, or are only likely to be useful if you
761 already know what they are or have specialized
762 requirements (such as packages containing only detached
769 Packages must not depend on packages with lower priority
770 values (excluding build-time dependencies). In order to
771 ensure this, the priorities of one or more packages may need
780 <heading>Binary packages
</heading>
783 The Debian GNU/Linux distribution is based on the Debian
784 package management system, called
<prgn>dpkg
</prgn>. Thus,
785 all packages in the Debian distribution must be provided
786 in the
<tt>.deb
</tt> file format.
790 <heading>The package name
</heading>
793 Every package must have a name that's unique within the Debian
798 The package name is included in the control field
799 <tt>Package
</tt>, the format of which is described
800 in
<ref id=
"f-Package">.
801 The package name is also included as a part of the file name
802 of the
<tt>.deb
</tt> file.
807 <heading>The version of a package
</heading>
810 Every package has a version number recorded in its
811 <tt>Version
</tt> control file field, described in
812 <ref id=
"f-Version">.
816 The package management system imposes an ordering on version
817 numbers, so that it can tell whether packages are being up- or
818 downgraded and so that package system front end applications
819 can tell whether a package it finds available is newer than
820 the one installed on the system. The version number format
821 has the most significant parts (as far as comparison is
822 concerned) at the beginning.
826 If an upstream package has problematic version numbers they
827 should be converted to a sane form for use in the
828 <tt>Version
</tt> field.
832 <heading>Version numbers based on dates
</heading>
835 In general, Debian packages should use the same version
836 numbers as the upstream sources.
840 However, in some cases where the upstream version number is
841 based on a date (e.g., a development
"snapshot" release) the
842 package management system cannot handle these version
843 numbers without epochs. For example, dpkg will consider
844 "96May01" to be greater than
"96Dec24".
848 To prevent having to use epochs for every new upstream
849 version, the date based portion of the version number
850 should be changed to the following format in such cases:
851 "19960501",
"19961224". It is up to the maintainer whether
852 they want to bother the upstream maintainer to change
853 the version numbers upstream, too.
857 Note that other version formats based on dates which are
858 parsed correctly by the package management system should
859 <em>not
</em> be changed.
863 Native Debian packages (i.e., packages which have been
864 written especially for Debian) whose version numbers include
865 dates should always use the
"YYYYMMDD" format.
872 <heading>The maintainer of a package
</heading>
875 Every package must have a Debian maintainer (the
876 maintainer may be one person or a group of people
877 reachable from a common email address, such as a mailing
878 list). The maintainer is responsible for ensuring that
879 the package is placed in the appropriate distributions.
883 The maintainer must be specified in the
884 <tt>Maintainer
</tt> control field with their correct name
885 and a working email address. If one person maintains
886 several packages, they should try to avoid having
887 different forms of their name and email address in
888 the
<tt>Maintainer
</tt> fields of those packages.
892 The format of the
<tt>Maintainer
</tt> control field is
893 described in
<ref id=
"f-Maintainer">.
897 If the maintainer of a package quits from the Debian
898 project,
"Debian QA Group"
899 <email>packages@qa.debian.org
</email> takes over the
900 maintainer-ship of the package until someone else
901 volunteers for that task. These packages are called
902 <em>orphaned packages
</em>.
<footnote>
903 The detailed procedure for doing this gracefully can
904 be found in the Debian Developer's Reference,
905 see
<ref id=
"related">.
910 <sect id=
"descriptions">
911 <heading>The description of a package
</heading>
914 Every Debian package must have an extended description
915 stored in the appropriate field of the control record.
916 The technical information about the format of the
917 <tt>Description
</tt> field is in
<ref id=
"f-Description">.
921 The description should describe the package (the program) to a
922 user (system administrator) who has never met it before so that
923 they have enough information to decide whether they want to
924 install it. This description should not just be copied verbatim
925 from the program's documentation.
929 Put important information first, both in the synopsis and
930 extended description. Sometimes only the first part of the
931 synopsis or of the description will be displayed. You can
932 assume that there will usually be a way to see the whole
933 extended description.
937 The description should also give information about the
938 significant dependencies and conflicts between this package
939 and others, so that the user knows why these dependencies and
940 conflicts have been declared.
944 Instructions for configuring or using the package should
945 not be included (that is what installation scripts,
946 manual pages, info files, etc., are for). Copyright
947 statements and other administrivia should not be included
948 either (that is what the copyright file is for).
951 <sect1 id=
"synopsis"><heading>The single line synopsis
</heading>
954 The single line synopsis should be kept brief - certainly
959 Do not include the package name in the synopsis line. The
960 display software knows how to display this already, and you
961 do not need to state it. Remember that in many situations
962 the user may only see the synopsis line - make it as
963 informative as you can.
968 <sect1 id=
"extendeddesc"><heading>The extended description
</heading>
971 Do not try to continue the single line synopsis into the
972 extended description. This will not work correctly when
973 the full description is displayed, and makes no sense
974 where only the summary (the single line synopsis) is
979 The extended description should describe what the package
980 does and how it relates to the rest of the system (in terms
981 of, for example, which subsystem it is which part of).
985 The description field needs to make sense to anyone, even
986 people who have no idea about any of the things the
987 package deals with.
<footnote>
988 The blurb that comes with a program in its
989 announcements and/or
<prgn>README
</prgn> files is
990 rarely suitable for use in a description. It is
991 usually aimed at people who are already in the
992 community where the package is used.
1001 <heading>Dependencies
</heading>
1004 Every package must specify the dependency information
1005 about other packages that are required for the first to
1010 For example, a dependency entry must be provided for any
1011 shared libraries required by a dynamically-linked executable
1012 binary in a package.
1016 Packages are not required to declare any dependencies they
1017 have on other packages which are marked
<tt>Essential
</tt>
1018 (see below), and should not do so unless they depend on a
1019 particular version of that package.
<footnote>
1021 Essential is needed in part to avoid unresolvable dependency
1022 loops on upgrade. If packages add unnecessary dependencies
1023 on packages in this set, the chances that there
1024 <strong>will
</strong> be an unresolvable dependency loop
1025 caused by forcing these Essential packages to be configured
1026 first before they need to be is greatly increased. It also
1027 increases the chances that frontends will be unable to
1028 <strong>calculate
</strong> an upgrade path, even if one
1032 Also, functionality is rarely ever removed from the
1033 Essential set, but
<em>packages
</em> have been removed from
1034 the Essential set when the functionality moved to a
1035 different package. So depending on these packages
<em>just
1036 in case
</em> they stop being essential does way more harm
1043 Sometimes, a package requires another package to be installed
1044 <em>and
</em> configured before it can be installed. In this
1045 case, you must specify a
<tt>Pre-Depends
</tt> entry for
1050 You should not specify a
<tt>Pre-Depends
</tt> entry for a
1051 package before this has been discussed on the
1052 <tt>debian-devel
</tt> mailing list and a consensus about
1053 doing that has been reached.
1057 The format of the package interrelationship control fields is
1058 described in
<ref id=
"relationships">.
1062 <sect id=
"virtual_pkg">
1063 <heading>Virtual packages
</heading>
1066 Sometimes, there are several packages which offer
1067 more-or-less the same functionality. In this case, it's
1068 useful to define a
<em>virtual package
</em> whose name
1069 describes that common functionality. (The virtual
1070 packages only exist logically, not physically; that's why
1071 they are called
<em>virtual
</em>.) The packages with this
1072 particular function will then
<em>provide
</em> the virtual
1073 package. Thus, any other package requiring that function
1074 can simply depend on the virtual package without having to
1075 specify all possible packages individually.
1079 All packages should use virtual package names where
1080 appropriate, and arrange to create new ones if necessary.
1081 They should not use virtual package names (except privately,
1082 amongst a cooperating group of packages) unless they have
1083 been agreed upon and appear in the list of virtual package
1084 names. (See also
<ref id=
"virtual">)
1088 The latest version of the authoritative list of virtual
1089 package names can be found in the
<tt>debian-policy
</tt> package.
1090 It is also available from the Debian web mirrors at
1091 <tt><url name=
"/doc/packaging-manuals/virtual-package-names-list.txt"
1092 id=
"http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1096 The procedure for updating the list is described in the preface
1103 <heading>Base system
</heading>
1106 The
<tt>base system
</tt> is a minimum subset of the Debian
1107 GNU/Linux system that is installed before everything else
1108 on a new system. Only very few packages are allowed to form
1109 part of the base system, in order to keep the required disk
1114 The base system consists of all those packages with priority
1115 <tt>required
</tt> or
<tt>important
</tt>. Many of them will
1116 be tagged
<tt>essential
</tt> (see below).
1121 <heading>Essential packages
</heading>
1124 Essential is defined as the minimal set of functionality that
1125 must be available and usable on the system at all times, even
1126 when packages are in an unconfigured (but unpacked) state.
1127 Packages are tagged
<tt>essential
</tt> for a system using the
1128 <tt>Essential
</tt> control file field. The format of the
1129 <tt>Essential
</tt> control field is described in
<ref
1134 Since these packages cannot be easily removed (one has to
1135 specify an extra
<em>force option
</em> to
1136 <prgn>dpkg
</prgn> to do so), this flag must not be used
1137 unless absolutely necessary. A shared library package
1138 must not be tagged
<tt>essential
</tt>; dependencies will
1139 prevent its premature removal, and we need to be able to
1140 remove it when it has been superseded.
1144 Since dpkg will not prevent upgrading of other packages
1145 while an
<tt>essential
</tt> package is in an unconfigured
1146 state, all
<tt>essential
</tt> packages must supply all of
1147 their core functionality even when unconfigured. If the
1148 package cannot satisfy this requirement it must not be
1149 tagged as essential, and any packages depending on this
1150 package must instead have explicit dependency fields as
1155 Maintainers should take great care in adding any programs,
1156 interfaces, or functionality to
<tt>essential
</tt> packages.
1157 Packages may assume that functionality provided by
1158 <tt>essential
</tt> packages is always available without
1159 declaring explicit dependencies, which means that removing
1160 functionality from the Essential set is very difficult and is
1161 almost never done. Any capability added to an
1162 <tt>essential
</tt> package therefore creates an obligation to
1163 support that capability as part of the Essential set in
1168 You must not tag any packages
<tt>essential
</tt> before
1169 this has been discussed on the
<tt>debian-devel
</tt>
1170 mailing list and a consensus about doing that has been
1175 <sect id=
"maintscripts">
1176 <heading>Maintainer Scripts
</heading>
1179 The package installation scripts should avoid producing
1180 output which is unnecessary for the user to see and
1181 should rely on
<prgn>dpkg
</prgn> to stave off boredom on
1182 the part of a user installing many packages. This means,
1183 amongst other things, using the
<tt>--quiet
</tt> option on
1184 <prgn>install-info
</prgn>.
1188 Errors which occur during the execution of an installation
1189 script must be checked and the installation must not
1190 continue after an error.
1194 Note that in general
<ref id=
"scripts"> applies to package
1195 maintainer scripts, too.
1199 You should not use
<prgn>dpkg-divert
</prgn> on a file
1200 belonging to another package without consulting the
1201 maintainer of that package first.
1205 All packages which supply an instance of a common command
1206 name (or, in general, filename) should generally use
1207 <prgn>update-alternatives
</prgn>, so that they may be
1208 installed together. If
<prgn>update-alternatives
</prgn>
1209 is not used, then each package must use
1210 <tt>Conflicts
</tt> to ensure that other packages are
1211 de-installed. (In this case, it may be appropriate to
1212 specify a conflict against earlier versions of something
1213 that previously did not use
1214 <prgn>update-alternatives
</prgn>; this is an exception to
1215 the usual rule that versioned conflicts should be
1219 <sect1 id=
"maintscriptprompt">
1220 <heading>Prompting in maintainer scripts
</heading>
1222 Package maintainer scripts may prompt the user if
1223 necessary. Prompting must be done by communicating
1224 through a program, such as
<prgn>debconf
</prgn>, which
1225 conforms to the Debian Configuration Management
1226 Specification, version
2 or higher.
1230 Packages which are essential, or which are dependencies of
1231 essential packages, may fall back on another prompting method
1232 if no such interface is available when they are executed.
1236 The Debian Configuration Management Specification is included
1237 in the
<file>debconf_specification
</file> files in the
1238 <package>debian-policy
</package> package.
1239 It is also available from the Debian web mirrors at
1240 <tt><url name=
"/doc/packaging-manuals/debconf_specification.html"
1241 id=
"http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1245 Packages which use the Debian Configuration Management
1246 Specification may contain an additional
1247 <prgn>config
</prgn> script and a
<tt>templates
</tt>
1248 file in their control archive
<footnote>
1249 The control.tar.gz inside the .deb.
1250 See
<manref name=
"deb" section=
"5">.
1252 The
<prgn>config
</prgn> script might be run before the
1253 <prgn>preinst
</prgn> script, and before the package is unpacked
1254 or any of its dependencies or pre-dependencies are satisfied.
1255 Therefore it must work using only the tools present in
1256 <em>essential
</em> packages.
<footnote>
1257 <package>Debconf
</package> or another tool that
1258 implements the Debian Configuration Management
1259 Specification will also be installed, and any
1260 versioned dependencies on it will be satisfied
1261 before preconfiguration begins.
1266 Packages which use the Debian Configuration Management
1267 Specification must allow for translation of their user-visible
1268 messages by using a gettext-based system such as the one
1269 provided by the
<package>po-debconf
</package> package.
1273 Packages should try to minimize the amount of prompting
1274 they need to do, and they should ensure that the user
1275 will only ever be asked each question once. This means
1276 that packages should try to use appropriate shared
1277 configuration files (such as
<file>/etc/papersize
</file> and
1278 <file>/etc/news/server
</file>), and shared
1279 <package>debconf
</package> variables rather than each
1280 prompting for their own list of required pieces of
1285 It also means that an upgrade should not ask the same
1286 questions again, unless the user has used
1287 <tt>dpkg --purge
</tt> to remove the package's configuration.
1288 The answers to configuration questions should be stored in an
1289 appropriate place in
<file>/etc
</file> so that the user can
1290 modify them, and how this has been done should be
1295 If a package has a vitally important piece of
1296 information to pass to the user (such as
"don't run me
1297 as I am, you must edit the following configuration files
1298 first or you risk your system emitting badly-formatted
1299 messages"), it should display this in the
1300 <prgn>config
</prgn> or
<prgn>postinst
</prgn> script and
1301 prompt the user to hit return to acknowledge the
1302 message. Copyright messages do not count as vitally
1303 important (they belong in
1304 <file>/usr/share/doc/
<var>package
</var>/copyright
</file>);
1305 neither do instructions on how to use a program (these
1306 should be in on-line documentation, where all the users
1311 Any necessary prompting should almost always be confined
1312 to the
<prgn>config
</prgn> or
<prgn>postinst
</prgn>
1313 script. If it is done in the
<prgn>postinst
</prgn>, it
1314 should be protected with a conditional so that
1315 unnecessary prompting doesn't happen if a package's
1316 installation fails and the
<prgn>postinst
</prgn> is
1317 called with
<tt>abort-upgrade
</tt>,
1318 <tt>abort-remove
</tt> or
<tt>abort-deconfigure
</tt>.
1328 <heading>Source packages
</heading>
1330 <sect id=
"standardsversion">
1331 <heading>Standards conformance
</heading>
1334 Source packages should specify the most recent version number
1335 of this policy document with which your package complied
1336 when it was last updated.
1340 This information may be used to file bug reports
1341 automatically if your package becomes too much out of date.
1345 The version is specified in the
<tt>Standards-Version
</tt>
1347 The format of the
<tt>Standards-Version
</tt> field is
1348 described in
<ref id=
"f-Standards-Version">.
1352 You should regularly, and especially if your package has
1353 become out of date, check for the newest Policy Manual
1354 available and update your package, if necessary. When your
1355 package complies with the new standards you should update the
1356 <tt>Standards-Version
</tt> source package field and
1357 release it.
<footnote>
1358 See the file
<file>upgrading-checklist
</file> for
1359 information about policy which has changed between
1360 different versions of this document.
1366 <sect id=
"pkg-relations">
1367 <heading>Package relationships
</heading>
1370 Source packages should specify which binary packages they
1371 require to be installed or not to be installed in order to
1372 build correctly. For example, if building a package
1373 requires a certain compiler, then the compiler should be
1374 specified as a build-time dependency.
1378 It is not necessary to explicitly specify build-time
1379 relationships on a minimal set of packages that are always
1380 needed to compile, link and put in a Debian package a
1381 standard
"Hello World!" program written in C or C++. The
1382 required packages are called
<em>build-essential
</em>, and
1383 an informational list can be found in
1384 <file>/usr/share/doc/build-essential/list
</file> (which is
1385 contained in the
<tt>build-essential
</tt>
1388 <list compact=
"compact">
1390 This allows maintaining the list separately
1391 from the policy documents (the list does not
1392 need the kind of control that the policy
1396 Having a separate package allows one to install
1397 the build-essential packages on a machine, as
1398 well as allowing other packages such as tasks to
1399 require installation of the build-essential
1400 packages using the depends relation.
1403 The separate package allows bug reports against
1404 the list to be categorized separately from
1405 the policy management process in the BTS.
1412 When specifying the set of build-time dependencies, one
1413 should list only those packages explicitly required by the
1414 build. It is not necessary to list packages which are
1415 required merely because some other package in the list of
1416 build-time dependencies depends on them.
<footnote>
1417 The reason for this is that dependencies change, and
1418 you should list all those packages, and
<em>only
</em>
1419 those packages that
<em>you
</em> need directly. What
1420 others need is their business. For example, if you
1421 only link against
<file>libimlib
</file>, you will need to
1422 build-depend on
<package>libimlib2-dev
</package> but
1423 not against any
<tt>libjpeg*
</tt> packages, even
1424 though
<tt>libimlib2-dev
</tt> currently depends on
1425 them: installation of
<package>libimlib2-dev
</package>
1426 will automatically ensure that all of its run-time
1427 dependencies are satisfied.
1432 If build-time dependencies are specified, it must be
1433 possible to build the package and produce working binaries
1434 on a system with only essential and build-essential
1435 packages installed and also those required to satisfy the
1436 build-time relationships (including any implied
1437 relationships). In particular, this means that version
1438 clauses should be used rigorously in build-time
1439 relationships so that one cannot produce bad or
1440 inconsistently configured packages when the relationships
1441 are properly satisfied.
1445 <ref id=
"relationships"> explains the technical details.
1450 <heading>Changes to the upstream sources
</heading>
1453 If changes to the source code are made that are not
1454 specific to the needs of the Debian system, they should be
1455 sent to the upstream authors in whatever form they prefer
1456 so as to be included in the upstream version of the
1461 If you need to configure the package differently for
1462 Debian or for Linux, and the upstream source doesn't
1463 provide a way to do so, you should add such configuration
1464 facilities (for example, a new
<prgn>autoconf
</prgn> test
1465 or
<tt>#define
</tt>) and send the patch to the upstream
1466 authors, with the default set to the way they originally
1467 had it. You can then easily override the default in your
1468 <file>debian/rules
</file> or wherever is appropriate.
1472 You should make sure that the
<prgn>configure
</prgn> utility
1473 detects the correct architecture specification string
1474 (refer to
<ref id=
"arch-spec"> for details).
1478 If you need to edit a
<prgn>Makefile
</prgn> where GNU-style
1479 <prgn>configure
</prgn> scripts are used, you should edit the
1480 <file>.in
</file> files rather than editing the
1481 <prgn>Makefile
</prgn> directly. This allows the user to
1482 reconfigure the package if necessary. You should
1483 <em>not
</em> configure the package and edit the generated
1484 <prgn>Makefile
</prgn>! This makes it impossible for someone
1485 else to later reconfigure the package without losing the
1491 <sect id=
"dpkgchangelog">
1492 <heading>Debian changelog:
<file>debian/changelog
</file></heading>
1495 Changes in the Debian version of the package should be
1496 briefly explained in the Debian changelog file
1497 <file>debian/changelog
</file>.
<footnote>
1499 Mistakes in changelogs are usually best rectified by
1500 making a new changelog entry rather than
"rewriting
1501 history" by editing old changelog entries.
1504 This includes modifications
1505 made in the Debian package compared to the upstream one
1506 as well as other changes and updates to the package.
1508 Although there is nothing stopping an author who is also
1509 the Debian maintainer from using this changelog for all
1510 their changes, it will have to be renamed if the Debian
1511 and upstream maintainers become different people. In such
1512 a case, however, it might be better to maintain the package
1513 as a non-native package.
1518 The format of the
<file>debian/changelog
</file> allows the
1519 package building tools to discover which version of the package
1520 is being built and find out other release-specific information.
1524 That format is a series of entries like this:
1526 <example compact=
"compact">
1527 <var>package
</var> (
<var>version
</var>)
<var>distribution(s)
</var>; urgency=
<var>urgency
</var>
1529 [optional blank line(s), stripped]
1531 *
<var>change details
</var>
1532 <var>more change details
</var>
1534 [blank line(s), included in output of dpkg-parsechangelog]
1536 *
<var>even more change details
</var>
1538 [optional blank line(s), stripped]
1540 --
<var>maintainer name
</var> <<var>email address
</var>><var>[two spaces]
</var> <var>date
</var>
1545 <var>package
</var> and
<var>version
</var> are the source
1546 package name and version number.
1550 <var>distribution(s)
</var> lists the distributions where
1551 this version should be installed when it is uploaded - it
1552 is copied to the
<tt>Distribution
</tt> field in the
1553 <file>.changes
</file> file. See
<ref id=
"f-Distribution">.
1557 <var>urgency
</var> is the value for the
<tt>Urgency
</tt>
1558 field in the
<file>.changes
</file> file for the upload
1559 (see
<ref id=
"f-Urgency">). It is not possible to specify
1560 an urgency containing commas; commas are used to separate
1561 <tt><var>keyword
</var>=
<var>value
</var></tt> settings in the
1562 <prgn>dpkg
</prgn> changelog format (though there is
1563 currently only one useful
<var>keyword
</var>,
1568 The change details may in fact be any series of lines
1569 starting with at least two spaces, but conventionally each
1570 change starts with an asterisk and a separating space and
1571 continuation lines are indented so as to bring them in
1572 line with the start of the text above. Blank lines may be
1573 used here to separate groups of changes, if desired.
1577 If this upload resolves bugs recorded in the Bug Tracking
1578 System (BTS), they may be automatically closed on the
1579 inclusion of this package into the Debian archive by
1580 including the string:
<tt>closes: Bug#
<var>nnnnn
</var></tt>
1581 in the change details.
<footnote>
1582 To be precise, the string should match the following
1583 Perl regular expression:
1585 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1587 Then all of the bug numbers listed will be closed by the
1588 archive maintenance script (
<prgn>katie
</prgn>) using the
1589 <var>version
</var> of the changelog entry.
1591 This information is conveyed via the
<tt>Closes
</tt> field
1592 in the
<tt>.changes
</tt> file (see
<ref id=
"f-Closes">).
1596 The maintainer name and email address used in the changelog
1597 should be the details of the person uploading
<em>this
</em>
1598 version. They are
<em>not
</em> necessarily those of the
1599 usual package maintainer. The information here will be
1600 copied to the
<tt>Changed-By
</tt> field in the
1601 <tt>.changes
</tt> file (see
<ref id=
"f-Changed-By">),
1602 and then later used to send an acknowledgement when the
1603 upload has been installed.
1607 The
<var>date
</var> must be in RFC822 format
<footnote>
1608 This is generated by
<tt>date -R
</tt>.
1609 </footnote>; it must include the time zone specified
1610 numerically, with the time zone name or abbreviation
1611 optionally present as a comment in parentheses.
1615 The first
"title" line with the package name must start
1616 at the left hand margin. The
"trailer" line with the
1617 maintainer and date details must be preceded by exactly
1618 one space. The maintainer details and the date must be
1619 separated by exactly two spaces.
1623 The entire changelog must be encoded in UTF-
8.
1627 For more information on placement of the changelog files
1628 within binary packages, please see
<ref id=
"changelogs">.
1632 <sect id=
"dpkgcopyright">
1633 <heading>Copyright:
<file>debian/copyright
</file></heading>
1635 Every package must be accompanied by a verbatim copy of
1636 its copyright and distribution license in the file
1637 <file>/usr/share/doc/
<var>package
</var>/copyright
</file>
1638 (see
<ref id=
"copyrightfile"> for further details). Also see
1639 <ref id=
"pkgcopyright"> for further considerations relayed
1640 to copyrights for packages.
1644 <heading>Error trapping in makefiles
</heading>
1647 When
<prgn>make
</prgn> invokes a command in a makefile
1648 (including your package's upstream makefiles and
1649 <file>debian/rules
</file>), it does so using
<prgn>sh
</prgn>. This
1650 means that
<prgn>sh
</prgn>'s usual bad error handling
1651 properties apply: if you include a miniature script as one
1652 of the commands in your makefile you'll find that if you
1653 don't do anything about it then errors are not detected
1654 and
<prgn>make
</prgn> will blithely continue after
1659 Every time you put more than one shell command (this
1660 includes using a loop) in a makefile command you
1661 must make sure that errors are trapped. For
1662 simple compound commands, such as changing directory and
1663 then running a program, using
<tt>&&</tt> rather
1664 than semicolon as a command separator is sufficient. For
1665 more complex commands including most loops and
1666 conditionals you should include a separate
<tt>set -e
</tt>
1667 command at the start of every makefile command that's
1668 actually one of these miniature shell scripts.
1672 <sect id=
"timestamps">
1673 <heading>Time Stamps
</heading>
1675 Maintainers should preserve the modification times of the
1676 upstream source files in a package, as far as is reasonably
1678 The rationale is that there is some information conveyed
1679 by knowing the age of the file, for example, you could
1680 recognize that some documentation is very old by looking
1681 at the modification time, so it would be nice if the
1682 modification time of the upstream source would be
1688 <sect id=
"restrictions">
1689 <heading>Restrictions on objects in source packages
</heading>
1692 The source package may not contain any hard links
<footnote>
1694 This is not currently detected when building source
1695 packages, but only when extracting
1699 Hard links may be permitted at some point in the
1700 future, but would require a fair amount of
1703 </footnote>, device special files, sockets or setuid or
1704 setgid files.
<footnote>
1705 Setgid directories are allowed.
1710 <sect id=
"debianrules">
1711 <heading>Main building script:
<file>debian/rules
</file></heading>
1714 This file must be an executable makefile, and contains the
1715 package-specific recipes for compiling the package and
1716 building binary package(s) from the source.
1720 It must start with the line
<tt>#!/usr/bin/make -f
</tt>,
1721 so that it can be invoked by saying its name rather than
1722 invoking
<prgn>make
</prgn> explicitly.
1726 Since an interactive
<file>debian/rules
</file> script makes it
1727 impossible to auto-compile that package and also makes it
1728 hard for other people to reproduce the same binary
1729 package, all
<em>required targets
</em> MUST be
1730 non-interactive. At a minimum, required targets are the
1731 ones called by
<prgn>dpkg-buildpackage
</prgn>, namely,
1732 <em>clean
</em>,
<em>binary
</em>,
<em>binary-arch
</em>,
1733 <em>binary-indep
</em>, and
<em>build
</em>. It also follows
1734 that any target that these targets depend on must also be
1739 The targets are as follows (required unless stated otherwise):
1741 <tag><tt>build
</tt></tag>
1744 The
<tt>build
</tt> target should perform all the
1745 configuration and compilation of the package.
1746 If a package has an interactive pre-build
1747 configuration routine, the Debianized source package
1748 must either be built after this has taken place (so
1749 that the binary package can be built without rerunning
1750 the configuration) or the configuration routine
1751 modified to become non-interactive. (The latter is
1752 preferable if there are architecture-specific features
1753 detected by the configuration routine.)
1757 For some packages, notably ones where the same
1758 source tree is compiled in different ways to produce
1759 two binary packages, the
<tt>build
</tt> target
1760 does not make much sense. For these packages it is
1761 good enough to provide two (or more) targets
1762 (
<tt>build-a
</tt> and
<tt>build-b
</tt> or whatever)
1763 for each of the ways of building the package, and a
1764 <tt>build
</tt> target that does nothing. The
1765 <tt>binary
</tt> target will have to build the
1766 package in each of the possible ways and make the
1767 binary package out of each.
1771 The
<tt>build
</tt> target must not do anything
1772 that might require root privilege.
1776 The
<tt>build
</tt> target may need to run the
1777 <tt>clean
</tt> target first - see below.
1781 When a package has a configuration and build routine
1782 which takes a long time, or when the makefiles are
1783 poorly designed, or when
<tt>build
</tt> needs to
1784 run
<tt>clean
</tt> first, it is a good idea to
1785 <tt>touch build
</tt> when the build process is
1786 complete. This will ensure that if
<tt>debian/rules
1787 build
</tt> is run again it will not rebuild the whole
1789 Another common way to do this is for
<tt>build
</tt>
1790 to depend on
<prgn>build-stamp
</prgn> and to do
1791 nothing else, and for the
<prgn>build-stamp
</prgn>
1792 target to do the building and to
<tt>touch
1793 build-stamp
</tt> on completion. This is
1794 especially useful if the build routine creates a
1795 file or directory called
<tt>build
</tt>; in such a
1796 case,
<tt>build
</tt> will need to be listed as
1797 a phony target (i.e., as a dependency of the
1798 <tt>.PHONY
</tt> target). See the documentation of
1799 <prgn>make
</prgn> for more information on phony
1805 <tag><tt>build-arch
</tt> (optional),
1806 <tt>build-indep
</tt> (optional)
1810 A package may also provide both of the targets
1811 <tt>build-arch
</tt> and
<tt>build-indep
</tt>.
1812 The
<tt>build-arch
</tt> target, if provided, should
1813 perform all the configuration and compilation required
1814 for producing all architecture-dependant binary packages
1815 (those packages for which the body of the
1816 <tt>Architecture
</tt> field in
<tt>debian/control
</tt>
1817 is not
<tt>all
</tt>).
1818 Similarly, the
<tt>build-indep
</tt> target, if
1819 provided, should perform all the configuration and
1820 compilation required for producing all
1821 architecture-independent binary packages
1822 (those packages for which the body of the
1823 <tt>Architecture
</tt> field in
<tt>debian/control
</tt>
1825 The
<tt>build
</tt> target should depend on those of the
1826 targets
<tt>build-arch
</tt> and
<tt>build-indep
</tt> that
1827 are provided in the rules file.
1831 If one or both of the targets
<tt>build-arch
</tt> and
1832 <tt>build-indep
</tt> are not provided, then invoking
1833 <file>debian/rules
</file> with one of the not-provided
1834 targets as arguments should produce a exit status code
1835 of
2. Usually this is provided automatically by make
1836 if the target is missing.
1840 The
<tt>build-arch
</tt> and
<tt>build-indep
</tt> targets
1841 must not do anything that might require root privilege.
1845 <tag><tt>binary
</tt>,
<tt>binary-arch
</tt>,
1846 <tt>binary-indep
</tt>
1850 The
<tt>binary
</tt> target must be all that is
1851 necessary for the user to build the binary package(s)
1852 produced from this source package. It is
1853 split into two parts:
<prgn>binary-arch
</prgn> builds
1854 the binary packages which are specific to a particular
1855 architecture, and
<tt>binary-indep
</tt> builds
1856 those which are not.
1859 <tt>binary
</tt> may be (and commonly is) a target with
1860 no commands which simply depends on
1861 <tt>binary-arch
</tt> and
<tt>binary-indep
</tt>.
1864 Both
<tt>binary-*
</tt> targets should depend on the
1865 <tt>build
</tt> target, or on the appropriate
1866 <tt>build-arch
</tt> or
<tt>build-indep
</tt> target, if
1867 provided, so that the package is built if it has not
1868 been already. It should then create the relevant
1869 binary package(s), using
<prgn>dpkg-gencontrol
</prgn> to
1870 make their control files and
<prgn>dpkg-deb
</prgn> to
1871 build them and place them in the parent of the top
1876 Both the
<tt>binary-arch
</tt> and
1877 <tt>binary-indep
</tt> targets
<em>must
</em> exist.
1878 If one of them has nothing to do (which will always be
1879 the case if the source generates only a single binary
1880 package, whether architecture-dependent or not), it
1881 must still exist and must always succeed.
1885 The
<tt>binary
</tt> targets must be invoked as
1887 The
<prgn>fakeroot
</prgn> package often allows one
1888 to build a package correctly even without being
1894 <tag><tt>clean
</tt></tag>
1897 This must undo any effects that the
<tt>build
</tt>
1898 and
<tt>binary
</tt> targets may have had, except
1899 that it should leave alone any output files created in
1900 the parent directory by a run of a
<tt>binary
</tt>
1905 If a
<tt>build
</tt> file is touched at the end of
1906 the
<tt>build
</tt> target, as suggested above, it
1907 should be removed as the first action that
1908 <tt>clean
</tt> performs, so that running
1909 <tt>build
</tt> again after an interrupted
1910 <tt>clean
</tt> doesn't think that everything is
1915 The
<tt>clean
</tt> target may need to be
1916 invoked as root if
<tt>binary
</tt> has been
1917 invoked since the last
<tt>clean
</tt>, or if
1918 <tt>build
</tt> has been invoked as root (since
1919 <tt>build
</tt> may create directories, for
1924 <tag><tt>get-orig-source
</tt> (optional)
</tag>
1927 This target fetches the most recent version of the
1928 original source package from a canonical archive site
1929 (via FTP or WWW, for example), does any necessary
1930 rearrangement to turn it into the original source
1931 tar file format described below, and leaves it in the
1936 This target may be invoked in any directory, and
1937 should take care to clean up any temporary files it
1942 This target is optional, but providing it if
1943 possible is a good idea.
1947 <tag><tt>patch
</tt> (optional)
</tag>
1950 This target performs whatever additional actions are
1951 required to make the source ready for editing (unpacking
1952 additional upstream archives, applying patches, etc.).
1953 It is recommended to be implemented for any package where
1954 <tt>dpkg-source -x
</tt> does not result in source ready
1955 for additional modification. See
1956 <ref id=
"readmesource">.
1962 The
<tt>build
</tt>,
<tt>binary
</tt> and
1963 <tt>clean
</tt> targets must be invoked with the current
1964 directory being the package's top-level directory.
1969 Additional targets may exist in
<file>debian/rules
</file>,
1970 either as published or undocumented interfaces or for the
1971 package's internal use.
1975 The architectures we build on and build for are determined
1976 by
<prgn>make
</prgn> variables using the utility
1977 <qref id=
"pkg-dpkg-architecture"><prgn>dpkg-architecture
</prgn></qref>.
1978 You can determine the
1979 Debian architecture and the GNU style architecture
1980 specification string for the build machine (the machine type
1981 we are building on) as well as for the host machine (the
1982 machine type we are building for). Here is a list of
1983 supported
<prgn>make
</prgn> variables:
1984 <list compact=
"compact">
1986 <tt>DEB_*_ARCH
</tt> (the Debian architecture)
1989 <tt>DEB_*_GNU_TYPE
</tt> (the GNU style architecture
1990 specification string)
1993 <tt>DEB_*_GNU_CPU
</tt> (the CPU part of
1994 <tt>DEB_*_GNU_TYPE
</tt>)
1997 <tt>DEB_*_GNU_SYSTEM
</tt> (the System part of
1998 <tt>DEB_*_GNU_TYPE
</tt>)
2000 where
<tt>*
</tt> is either
<tt>BUILD
</tt> for specification of
2001 the build machine or
<tt>HOST
</tt> for specification of the
2006 Backward compatibility can be provided in the rules file
2007 by setting the needed variables to suitable default
2008 values; please refer to the documentation of
2009 <prgn>dpkg-architecture
</prgn> for details.
2013 It is important to understand that the
<tt>DEB_*_ARCH
</tt>
2014 string only determines which Debian architecture we are
2015 building on or for. It should not be used to get the CPU
2016 or system information; the GNU style variables should be
2020 <sect1 id=
"debianrules-options">
2021 <heading><file>debian/rules
</file> and
2022 <tt>DEB_BUILD_OPTIONS
</tt></heading>
2025 Supporting the standardized environment variable
2026 <tt>DEB_BUILD_OPTIONS
</tt> is recommended. This variable can
2027 contain several flags to change how a package is compiled and
2028 built. Each flag must be in the form
<var>flag
</var> or
2029 <var>flag
</var>=
<var>options
</var>. If multiple flags are
2030 given, they must be separated by whitespace.
<footnote>
2031 Some packages support any delimiter, but whitespace is the
2032 easiest to parse inside a makefile and avoids ambiguity with
2033 flag values that contain commas.
2035 <var>flag
</var> must start with a lowercase letter
2036 (
<tt>a-z
</tt>) and consist only of lowercase letters,
2037 numbers (
<tt>0-
9</tt>), and the characters
2038 <tt>-
</tt> and
<tt>_
</tt> (hyphen and underscore).
2039 <var>options
</var> must not contain whitespace. The same
2040 tag should not be given multiple times with conflicting
2041 values. Package maintainers may assume that
2042 <tt>DEB_BUILD_OPTIONS
</tt> will not contain conflicting tags.
2046 The meaning of the following tags has been standardized:
2050 This tag says to not run any build-time test suite
2051 provided by the package.
2055 The presence of this tag means that the package should
2056 be compiled with a minimum of optimization. For C
2057 programs, it is best to add
<tt>-O0
</tt> to
2058 <tt>CFLAGS
</tt> (although this is usually the default).
2059 Some programs might fail to build or run at this level
2060 of optimization; it may be necessary to use
2061 <tt>-O1
</tt>, for example.
2065 This tag means that the debugging symbols should not be
2066 stripped from the binary during installation, so that
2067 debugging information may be included in the package.
2069 <tag>parallel=n
</tag>
2071 This tag means that the package should be built using up
2072 to
<tt>n
</tt> parallel processes if the package build
2073 system supports this.
<footnote>
2074 Packages built with
<tt>make
</tt> can often implement
2075 this by passing the
<tt>-j
</tt><var>n
</var> option to
2078 If the package build system does not support parallel
2079 builds, this string must be ignored. If the package
2080 build system only supports a lower level of concurrency
2081 than
<var>n
</var>, the package should be built using as
2082 many parallel processes as the package build system
2083 supports. It is up to the package maintainer to decide
2084 whether the package build times are long enough and the
2085 package build system is robust enough to make supporting
2086 parallel builds worthwhile.
2092 Unknown flags must be ignored by
<file>debian/rules
</file>.
2096 The following makefile snippet is an example of how one may
2097 implement the build options; you will probably have to
2098 massage this example in order to make it work for your
2100 <example compact=
"compact">
2103 INSTALL_FILE = $(INSTALL) -p -o root -g root -m
644
2104 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m
755
2105 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m
755
2106 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m
755
2108 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2113 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2114 INSTALL_PROGRAM += -s
2116 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2117 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2118 MAKEFLAGS += -j$(NUMJOBS)
2123 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2124 # Code to run the package test suite.
2131 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2132 <sect id=
"substvars">
2133 <heading>Variable substitutions:
<file>debian/substvars
</file></heading>
2136 When
<prgn>dpkg-gencontrol
</prgn>,
2137 <prgn>dpkg-genchanges
</prgn> and
<prgn>dpkg-source
</prgn>
2138 generate control files they perform variable substitutions
2139 on their output just before writing it. Variable
2140 substitutions have the form
<tt>${
<var>variable
</var>}
</tt>.
2141 The optional file
<file>debian/substvars
</file> contains
2142 variable substitutions to be used; variables can also be set
2143 directly from
<file>debian/rules
</file> using the
<tt>-V
</tt>
2144 option to the source packaging commands, and certain
2145 predefined variables are also available.
2149 The
<file>debian/substvars
</file> file is usually generated and
2150 modified dynamically by
<file>debian/rules
</file> targets, in
2151 which case it must be removed by the
<tt>clean
</tt> target.
2155 See
<manref name=
"deb-substvars" section=
"5"> for full
2156 details about source variable substitutions, including the
2157 format of
<file>debian/substvars
</file>.
</p>
2160 <sect id=
"debianwatch">
2161 <heading>Optional upstream source location:
<file>debian/watch
</file></heading>
2164 This is an optional, recommended control file for the
2165 <tt>uscan
</tt> utility which defines how to automatically
2166 scan ftp or http sites for newly available updates of the
2167 package. This is used by
<url id=
"
2168 http://dehs.alioth.debian.org/"> and other Debian QA tools
2169 to help with quality control and maintenance of the
2170 distribution as a whole.
2175 <sect id=
"debianfiles">
2176 <heading>Generated files list:
<file>debian/files
</file></heading>
2179 This file is not a permanent part of the source tree; it
2180 is used while building packages to record which files are
2181 being generated.
<prgn>dpkg-genchanges
</prgn> uses it
2182 when it generates a
<file>.changes
</file> file.
2186 It should not exist in a shipped source package, and so it
2187 (and any backup files or temporary files such as
2188 <file>files.new
</file><footnote>
2189 <file>files.new
</file> is used as a temporary file by
2190 <prgn>dpkg-gencontrol
</prgn> and
2191 <prgn>dpkg-distaddfile
</prgn> - they write a new
2192 version of
<tt>files
</tt> here before renaming it,
2193 to avoid leaving a corrupted copy if an error
2195 </footnote>) should be removed by the
2196 <tt>clean
</tt> target. It may also be wise to
2197 ensure a fresh start by emptying or removing it at the
2198 start of the
<tt>binary
</tt> target.
2202 When
<prgn>dpkg-gencontrol
</prgn> is run for a binary
2203 package, it adds an entry to
<file>debian/files
</file> for the
2204 <file>.deb
</file> file that will be created when
<tt>dpkg-deb
2205 --build
</tt> is run for that binary package. So for most
2206 packages all that needs to be done with this file is to
2207 delete it in the
<tt>clean
</tt> target.
2211 If a package upload includes files besides the source
2212 package and any binary packages whose control files were
2213 made with
<prgn>dpkg-gencontrol
</prgn> then they should be
2214 placed in the parent of the package's top-level directory
2215 and
<prgn>dpkg-distaddfile
</prgn> should be called to add
2216 the file to the list in
<file>debian/files
</file>.
</p>
2219 <sect id=
"embeddedfiles">
2220 <heading>Convenience copies of code
</heading>
2223 Some software packages include in their distribution convenience
2224 copies of code from other software packages, generally so that
2225 users compiling from source don't have to download multiple
2226 packages. Debian packages should not make use of these
2227 convenience copies unless the included package is explicitly
2228 intended to be used in this way.
<footnote>
2229 For example, parts of the GNU build system work like this.
2231 If the included code is already in the Debian archive in the
2232 form of a library, the Debian packaging should ensure that
2233 binary packages reference the libraries already in Debian and
2234 the convenience copy is not used. If the included code is not
2235 already in Debian, it should be packaged separately as a
2236 prerequisite if possible.
2238 Having multiple copies of the same code in Debian is
2239 inefficient, often creates either static linking or shared
2240 library conflicts, and, most importantly, increases the
2241 difficulty of handling security vulnerabilities in the
2247 <sect id=
"readmesource">
2248 <heading>Source package handling:
2249 <file>debian/README.source
</file></heading>
2252 If running
<prgn>dpkg-source -x
</prgn> on a source package
2253 doesn't produce the source of the package, ready for editing,
2254 and allow one to make changes and run
2255 <prgn>dpkg-buildpackage
</prgn> to produce a modified package
2256 without taking any additional steps, creating a
2257 <file>debian/README.source
</file> documentation file is
2258 recommended. This file should explain how to do all of the
2261 <item>Generate the fully patched source, in a form ready for
2262 editing, that would be built to create Debian
2263 packages. Doing this with a
<tt>patch
</tt> target in
2264 <file>debian/rules
</file> is recommended; see
2265 <ref id=
"debianrules">.
</item>
2266 <item>Modify the source and save those modifications so that
2267 they will be applied when building the package.
</item>
2268 <item>Remove source modifications that are currently being
2269 applied when building the package.
</item>
2270 <item>Optionally, document what steps are necessary to
2271 upgrade the Debian source package to a new upstream version,
2272 if applicable.
</item>
2274 This explanation should include specific commands and mention
2275 any additional required Debian packages. It should not assume
2276 familiarity with any specific Debian packaging system or patch
2281 This explanation may refer to a documentation file installed by
2282 one of the package's build dependencies provided that the
2283 referenced documentation clearly explains these tasks and is not
2284 a general reference manual.
2288 <file>debian/README.source
</file> may also include any other
2289 information that would be helpful to someone modifying the
2290 source package. Even if the package doesn't fit the above
2291 description, maintainers are encouraged to document in a
2292 <file>debian/README.source
</file> file any source package with a
2293 particularly complex or unintuitive source layout or build
2294 system (for example, a package that builds the same source
2295 multiple times to generate different binary packages).
2301 <chapt id=
"controlfields">
2302 <heading>Control files and their fields
</heading>
2305 The package management system manipulates data represented in
2306 a common format, known as
<em>control data
</em>, stored in
2307 <em>control files
</em>.
2308 Control files are used for source packages, binary packages and
2309 the
<file>.changes
</file> files which control the installation
2310 of uploaded files
<footnote>
2311 <prgn>dpkg
</prgn>'s internal databases are in a similar
2316 <sect id=
"controlsyntax">
2317 <heading>Syntax of control files
</heading>
2320 A control file consists of one or more paragraphs of
2322 The paragraphs are also sometimes referred to as stanzas.
2324 The paragraphs are separated by blank lines. Some control
2325 files allow only one paragraph; others allow several, in
2326 which case each paragraph usually refers to a different
2327 package. (For example, in source packages, the first
2328 paragraph refers to the source package, and later paragraphs
2329 refer to binary packages generated from the source.)
2333 Each paragraph consists of a series of data fields; each
2334 field consists of the field name, followed by a colon and
2335 then the data/value associated with that field. It ends at
2336 the end of the (logical) line. Horizontal whitespace
2337 (spaces and tabs) may occur immediately before or after the
2338 value and is ignored there; it is conventional to put a
2339 single space after the colon. For example, a field might
2341 <example compact=
"compact">
2344 the field name is
<tt>Package
</tt> and the field value
2349 Many fields' values may span several lines; in this case
2350 each continuation line must start with a space or a tab.
2351 Any trailing spaces or tabs at the end of individual
2352 lines of a field value are ignored.
2356 In fields where it is specified that lines may not wrap,
2357 only a single line of data is allowed and whitespace is not
2358 significant in a field body. Whitespace must not appear
2359 inside names (of packages, architectures, files or anything
2360 else) or version numbers, or between the characters of
2361 multi-character version relationships.
2365 Field names are not case-sensitive, but it is usual to
2366 capitalize the field names using mixed case as shown below.
2370 Blank lines, or lines consisting only of spaces and tabs,
2371 are not allowed within field values or between fields - that
2372 would mean a new paragraph.
2376 All control files must be encoded in UTF-
8.
2380 <sect id=
"sourcecontrolfiles">
2381 <heading>Source package control files --
<file>debian/control
</file></heading>
2384 The
<file>debian/control
</file> file contains the most vital
2385 (and version-independent) information about the source package
2386 and about the binary packages it creates.
2390 The first paragraph of the control file contains information about
2391 the source package in general. The subsequent sets each describe a
2392 binary package that the source tree builds.
2396 The fields in the general paragraph (the first one, for the source
2399 <list compact=
"compact">
2400 <item><qref id=
"f-Source"><tt>Source
</tt></qref> (mandatory)
</item>
2401 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2402 <item><qref id=
"f-Uploaders"><tt>Uploaders
</tt></qref></item>
2403 <item><qref id=
"f-Section"><tt>Section
</tt></qref> (recommended)
</item>
2404 <item><qref id=
"f-Priority"><tt>Priority
</tt></qref> (recommended)
</item>
2405 <item><qref id=
"sourcebinarydeps"><tt>Build-Depends
</tt> et al
</qref></item>
2406 <item><qref id=
"f-Standards-Version"><tt>Standards-Version
</tt></qref> (recommended)
</item>
2407 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2412 The fields in the binary package paragraphs are:
2414 <list compact=
"compact">
2415 <item><qref id=
"f-Package"><tt>Package
</tt></qref> (mandatory)
</item>
2416 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref> (mandatory)
</item>
2417 <item><qref id=
"f-Section"><tt>Section
</tt></qref> (recommended)
</item>
2418 <item><qref id=
"f-Priority"><tt>Priority
</tt></qref> (recommended)
</item>
2419 <item><qref id=
"f-Essential"><tt>Essential
</tt></qref></item>
2420 <item><qref id=
"binarydeps"><tt>Depends
</tt> et al
</qref></item>
2421 <item><qref id=
"f-Description"><tt>Description
</tt></qref> (mandatory)
</item>
2422 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2427 The syntax and semantics of the fields are described below.
2433 These fields are used by
<prgn>dpkg-gencontrol
</prgn> to
2434 generate control files for binary packages (see below), by
2435 <prgn>dpkg-genchanges
</prgn> to generate the
2436 <tt>.changes
</tt> file to accompany the upload, and by
2437 <prgn>dpkg-source
</prgn> when it creates the
2438 <file>.dsc
</file> source control file as part of a source
2439 archive. Many fields are permitted to span multiple lines in
2440 <file>debian/control
</file> but not in any other control
2441 file. These tools are responsible for removing the line
2442 breaks from such fields when using fields from
2443 <file>debian/control
</file> to generate other control files.
2447 The fields here may contain variable references - their
2448 values will be substituted by
<prgn>dpkg-gencontrol
</prgn>,
2449 <prgn>dpkg-genchanges
</prgn> or
<prgn>dpkg-source
</prgn>
2450 when they generate output control files.
2451 See
<ref id=
"substvars"> for details.
2455 In addition to the control file syntax described
<qref
2456 id=
"controlsyntax">above
</qref>, this file may also contain
2457 comment lines starting with
<tt>#
</tt> without any preceding
2458 whitespace. All such lines are ignored, even in the middle of
2459 continuation lines for a multiline field, and do not end a
2465 <sect id=
"binarycontrolfiles">
2466 <heading>Binary package control files --
<file>DEBIAN/control
</file></heading>
2469 The
<file>DEBIAN/control
</file> file contains the most vital
2470 (and version-dependent) information about a binary package.
2474 The fields in this file are:
2476 <list compact=
"compact">
2477 <item><qref id=
"f-Package"><tt>Package
</tt></qref> (mandatory)
</item>
2478 <item><qref id=
"f-Source"><tt>Source
</tt></qref></item>
2479 <item><qref id=
"f-Version"><tt>Version
</tt></qref> (mandatory)
</item>
2480 <item><qref id=
"f-Section"><tt>Section
</tt></qref> (recommended)
</item>
2481 <item><qref id=
"f-Priority"><tt>Priority
</tt></qref> (recommended)
</item>
2482 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref> (mandatory)
</item>
2483 <item><qref id=
"f-Essential"><tt>Essential
</tt></qref></item>
2484 <item><qref id=
"binarydeps"><tt>Depends
</tt> et al
</qref></item>
2485 <item><qref id=
"f-Installed-Size"><tt>Installed-Size
</tt></qref></item>
2486 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2487 <item><qref id=
"f-Description"><tt>Description
</tt></qref> (mandatory)
</item>
2488 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2493 <sect id=
"debiansourcecontrolfiles">
2494 <heading>Debian source control files --
<tt>.dsc
</tt></heading>
2497 This file contains a series of fields, identified and
2498 separated just like the fields in the control file of
2499 a binary package. The fields are listed below; their
2500 syntax is described above, in
<ref id=
"pkg-controlfields">.
2502 <list compact=
"compact">
2503 <item><qref id=
"f-Format"><tt>Format
</tt></qref> (mandatory)
</item>
2504 <item><qref id=
"f-Source"><tt>Source
</tt></qref> (mandatory)
</item>
2505 <item><qref id=
"f-Version"><tt>Version
</tt></qref> (mandatory)
</item>
2506 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2507 <item><qref id=
"f-Uploaders"><tt>Uploaders
</tt></qref></item>
2508 <item><qref id=
"f-Binary"><tt>Binary
</tt></qref></item>
2509 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref></item>
2510 <item><qref id=
"sourcebinarydeps"><tt>Build-Depends
</tt> et al
</qref></item>
2511 <item><qref id=
"f-Standards-Version"><tt>Standards-Version
</tt></qref> (recommended)
</item>
2512 <item><qref id=
"f-Files"><tt>Files
</tt></qref> (mandatory)
</item>
2513 <item><qref id=
"f-Homepage"><tt>Homepage
</tt></qref></item>
2518 The source package control file is generated by
2519 <prgn>dpkg-source
</prgn> when it builds the source
2520 archive, from other files in the source package,
2521 described above. When unpacking, it is checked against
2522 the files and directories in the other parts of the
2528 <sect id=
"debianchangesfiles">
2529 <heading>Debian changes files --
<file>.changes
</file></heading>
2532 The .changes files are used by the Debian archive maintenance
2533 software to process updates to packages. They contain one
2534 paragraph which contains information from the
2535 <tt>debian/control
</tt> file and other data about the
2536 source package gathered via
<tt>debian/changelog
</tt>
2537 and
<tt>debian/rules
</tt>.
2541 The fields in this file are:
2543 <list compact=
"compact">
2544 <item><qref id=
"f-Format"><tt>Format
</tt></qref> (mandatory)
</item>
2545 <item><qref id=
"f-Date"><tt>Date
</tt></qref> (mandatory)
</item>
2546 <item><qref id=
"f-Source"><tt>Source
</tt></qref> (mandatory)
</item>
2547 <item><qref id=
"f-Binary"><tt>Binary
</tt></qref> (mandatory)
</item>
2548 <item><qref id=
"f-Architecture"><tt>Architecture
</tt></qref> (mandatory)
</item>
2549 <item><qref id=
"f-Version"><tt>Version
</tt></qref> (mandatory)
</item>
2550 <item><qref id=
"f-Distribution"><tt>Distribution
</tt></qref> (mandatory)
</item>
2551 <item><qref id=
"f-Urgency"><tt>Urgency
</tt></qref> (recommended)
</item>
2552 <item><qref id=
"f-Maintainer"><tt>Maintainer
</tt></qref> (mandatory)
</item>
2553 <item><qref id=
"f-Changed-By"><tt>Changed-By
</tt></qref></item>
2554 <item><qref id=
"f-Description"><tt>Description
</tt></qref> (mandatory)
</item>
2555 <item><qref id=
"f-Closes"><tt>Closes
</tt></qref></item>
2556 <item><qref id=
"f-Changes"><tt>Changes
</tt></qref> (mandatory)
</item>
2557 <item><qref id=
"f-Files"><tt>Files
</tt></qref> (mandatory)
</item>
2562 <sect id=
"controlfieldslist">
2563 <heading>List of fields
</heading>
2565 <sect1 id=
"f-Source">
2566 <heading><tt>Source
</tt></heading>
2569 This field identifies the source package name.
2573 In
<file>debian/control
</file> or a
<file>.dsc
</file> file,
2574 this field must contain only the name of the source package.
2578 In a binary package control file or a
<file>.changes
</file>
2579 file, the source package name may be followed by a version
2580 number in parentheses
<footnote>
2581 It is customary to leave a space after the package name
2582 if a version number is specified.
2584 This version number may be omitted (and is, by
2585 <prgn>dpkg-gencontrol
</prgn>) if it has the same value as
2586 the
<tt>Version
</tt> field of the binary package in
2587 question. The field itself may be omitted from a binary
2588 package control file when the source package has the same
2589 name and version as the binary package.
2593 Package names must consist only of lower case letters
2594 (
<tt>a-z
</tt>), digits (
<tt>0-
9</tt>), plus (
<tt>+
</tt>)
2595 and minus (
<tt>-
</tt>) signs, and periods (
<tt>.
</tt>).
2596 They must be at least two characters long and must start
2597 with an alphanumeric character.
2601 <sect1 id=
"f-Maintainer">
2602 <heading><tt>Maintainer
</tt></heading>
2605 The package maintainer's name and email address. The name
2606 should come first, then the email address inside angle
2607 brackets
<tt><>
</tt> (in RFC822 format).
2611 If the maintainer's name contains a full stop then the
2612 whole field will not work directly as an email address due
2613 to a misfeature in the syntax specified in RFC822; a
2614 program using this field as an address must check for this
2615 and correct the problem if necessary (for example by
2616 putting the name in round brackets and moving it to the
2617 end, and bringing the email address forward).
2621 <sect1 id=
"f-Uploaders">
2622 <heading><tt>Uploaders
</tt></heading>
2625 List of the names and email addresses of co-maintainers of
2626 the package, if any. If the package has other maintainers
2627 beside the one named in the
2628 <qref id=
"f-Maintainer">Maintainer field
</qref>, their
2629 names and email addresses should be listed here. The
2630 format is the same as that of the Maintainer tag, and
2631 multiple entries should be comma separated. Currently,
2632 this field is restricted to a single line of data. This
2633 is an optional field.
2636 Any parser that interprets the Uploaders field in
2637 <file>debian/control
</file> must permit it to span multiple
2638 lines. Line breaks in an Uploaders field that spans multiple
2639 lines are not significant and the semantics of the field are
2640 the same as if the line breaks had not been present.
2644 <sect1 id=
"f-Changed-By">
2645 <heading><tt>Changed-By
</tt></heading>
2648 The name and email address of the person who changed the
2649 said package. Usually the name of the maintainer.
2650 All the rules for the Maintainer field apply here, too.
2654 <sect1 id=
"f-Section">
2655 <heading><tt>Section
</tt></heading>
2658 This field specifies an application area into which the package
2659 has been classified. See
<ref id=
"subsections">.
2663 When it appears in the
<file>debian/control
</file> file,
2664 it gives the value for the subfield of the same name in
2665 the
<tt>Files
</tt> field of the
<file>.changes
</file> file.
2666 It also gives the default for the same field in the binary
2671 <sect1 id=
"f-Priority">
2672 <heading><tt>Priority
</tt></heading>
2675 This field represents how important that it is that the user
2676 have the package installed. See
<ref id=
"priorities">.
2680 When it appears in the
<file>debian/control
</file> file,
2681 it gives the value for the subfield of the same name in
2682 the
<tt>Files
</tt> field of the
<file>.changes
</file> file.
2683 It also gives the default for the same field in the binary
2688 <sect1 id=
"f-Package">
2689 <heading><tt>Package
</tt></heading>
2692 The name of the binary package.
2696 Package names must consist only of lower case letters
2697 (
<tt>a-z
</tt>), digits (
<tt>0-
9</tt>), plus (
<tt>+
</tt>)
2698 and minus (
<tt>-
</tt>) signs, and periods (
<tt>.
</tt>).
2699 They must be at least two characters long and must start
2700 with an alphanumeric character.
2704 <sect1 id=
"f-Architecture">
2705 <heading><tt>Architecture
</tt></heading>
2708 Depending on context and the control file used, the
2709 <tt>Architecture
</tt> field can include the following sets of
2712 <item>A unique single word identifying a Debian machine
2713 architecture as described in
<ref id=
"arch-spec">.
2714 <item><tt>all
</tt>, which indicates an
2715 architecture-independent package.
2716 <item><tt>any
</tt>, which indicates a package available
2717 for building on any architecture.
2718 <item><tt>source
</tt>, which indicates a source package.
2723 In the main
<file>debian/control
</file> file in the source
2724 package, this field may contain the special value
2725 <tt>any
</tt>, the special value
<tt>all
</tt>, or a list of
2726 architectures separated by spaces. If
<tt>any
</tt> or
2727 <tt>all
</tt> appear, they must be the entire contents of the
2728 field. Most packages will use either
<tt>any
</tt> or
2729 <tt>all
</tt>. Specifying a specific list of architectures is
2730 for the minority of cases where a program is not portable or
2731 is not useful on some architectures, and where possible the
2732 program should be made portable instead.
2736 In the source package control file
<file>.dsc
</file>, this
2737 field may contain either the special value
<tt>any
</tt> or a
2738 list of architectures separated by spaces. If a list is given,
2739 it may include (or consist solely of) the special value
2740 <tt>all
</tt>. In other words, in
<file>.dsc
</file> files
2741 unlike the
<file>debian/control
</file>,
<tt>all
</tt> may occur
2742 in combination with specific architectures. The
2743 <tt>Architecture
</tt> field in the source package control file
2744 <file>.dsc
</file> is generally constructed from the
2745 <tt>Architecture
</tt> fields in the
2746 <file>debian/control
</file> in the source package.
2750 Specifying
<tt>any
</tt> indicates that the source package
2751 isn't dependent on any particular architecture and should
2752 compile fine on any one. The produced binary package(s)
2753 will either be specific to whatever the current build
2754 architecture is or will be architecture-independent.
2758 Specifying only
<tt>all
</tt> indicates that the source package
2759 will only build architecture-independent packages. If this is
2760 the case,
<tt>all
</tt> must be used rather than
<tt>any
</tt>;
2761 <tt>any
</tt> implies that the source package will build at
2762 least one architecture-dependent package.
2766 Specifying a list of architectures indicates that the source
2767 will build an architecture-dependent package, and will only
2768 work correctly on the listed architectures. If the source
2769 package also builds at least one architecture-independent
2770 package,
<tt>all
</tt> will also be included in the list.
2774 In a
<file>.changes
</file> file, the
<tt>Architecture
</tt>
2775 field lists the architecture(s) of the package(s)
2776 currently being uploaded. This will be a list; if the
2777 source for the package is also being uploaded, the special
2778 entry
<tt>source
</tt> is also present.
<tt>all
</tt> will be
2779 present if any architecture-independent packages are being
2780 uploaded.
<tt>any
</tt> may never occur in the
2781 <tt>Architecture
</tt> field in the
<file>.changes
</file>
2786 See
<ref id=
"debianrules"> for information how to get the
2787 architecture for the build process.
2791 <sect1 id=
"f-Essential">
2792 <heading><tt>Essential
</tt></heading>
2795 This is a boolean field which may occur only in the
2796 control file of a binary package or in a per-package fields
2797 paragraph of a main source control data file.
2801 If set to
<tt>yes
</tt> then the package management system
2802 will refuse to remove the package (upgrading and replacing
2803 it is still possible). The other possible value is
<tt>no
</tt>,
2804 which is the same as not having the field at all.
2809 <heading>Package interrelationship fields:
2810 <tt>Depends
</tt>,
<tt>Pre-Depends
</tt>,
2811 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
2812 <tt>Breaks
</tt>,
<tt>Conflicts
</tt>,
2813 <tt>Provides
</tt>,
<tt>Replaces
</tt>,
<tt>Enhances
</tt>
2817 These fields describe the package's relationships with
2818 other packages. Their syntax and semantics are described
2819 in
<ref id=
"relationships">.
</p>
2822 <sect1 id=
"f-Standards-Version">
2823 <heading><tt>Standards-Version
</tt></heading>
2826 The most recent version of the standards (the policy
2827 manual and associated texts) with which the package
2832 The version number has four components: major and minor
2833 version number and major and minor patch level. When the
2834 standards change in a way that requires every package to
2835 change the major number will be changed. Significant
2836 changes that will require work in many packages will be
2837 signaled by a change to the minor number. The major patch
2838 level will be changed for any change to the meaning of the
2839 standards, however small; the minor patch level will be
2840 changed when only cosmetic, typographical or other edits
2841 are made which neither change the meaning of the document
2842 nor affect the contents of packages.
2846 Thus only the first three components of the policy version
2847 are significant in the
<em>Standards-Version
</em> control
2848 field, and so either these three components or the all
2849 four components may be specified.
<footnote>
2850 In the past, people specified the full version number
2851 in the Standards-Version field, for example
"2.3.0.0".
2852 Since minor patch-level changes don't introduce new
2853 policy, it was thought it would be better to relax
2854 policy and only require the first
3 components to be
2855 specified, in this example
"2.3.0". All four
2856 components may still be used if someone wishes to do so.
2862 <sect1 id=
"f-Version">
2863 <heading><tt>Version
</tt></heading>
2866 The version number of a package. The format is:
2867 [
<var>epoch
</var><tt>:
</tt>]
<var>upstream_version
</var>[
<tt>-
</tt><var>debian_revision
</var>]
2871 The three components here are:
2873 <tag><var>epoch
</var></tag>
2876 This is a single (generally small) unsigned integer. It
2877 may be omitted, in which case zero is assumed. If it is
2878 omitted then the
<var>upstream_version
</var> may not
2883 It is provided to allow mistakes in the version numbers
2884 of older versions of a package, and also a package's
2885 previous version numbering schemes, to be left behind.
2889 <tag><var>upstream_version
</var></tag>
2892 This is the main part of the version number. It is
2893 usually the version number of the original (
"upstream")
2894 package from which the
<file>.deb
</file> file has been made,
2895 if this is applicable. Usually this will be in the same
2896 format as that specified by the upstream author(s);
2897 however, it may need to be reformatted to fit into the
2898 package management system's format and comparison
2903 The comparison behavior of the package management system
2904 with respect to the
<var>upstream_version
</var> is
2905 described below. The
<var>upstream_version
</var>
2906 portion of the version number is mandatory.
2910 The
<var>upstream_version
</var> may contain only
2911 alphanumerics
<footnote>
2912 Alphanumerics are
<tt>A-Za-z0-
9</tt> only.
2914 and the characters
<tt>.
</tt> <tt>+
</tt> <tt>-
</tt>
2915 <tt>:
</tt> <tt>~
</tt> (full stop, plus, hyphen, colon,
2916 tilde) and should start with a digit. If there is no
2917 <var>debian_revision
</var> then hyphens are not allowed;
2918 if there is no
<var>epoch
</var> then colons are not
2923 <tag><var>debian_revision
</var></tag>
2926 This part of the version number specifies the version of
2927 the Debian package based on the upstream version. It
2928 may contain only alphanumerics and the characters
2929 <tt>+
</tt> <tt>.
</tt> <tt>~
</tt> (plus, full stop,
2930 tilde) and is compared in the same way as the
2931 <var>upstream_version
</var> is.
2935 It is optional; if it isn't present then the
2936 <var>upstream_version
</var> may not contain a hyphen.
2937 This format represents the case where a piece of
2938 software was written specifically to be turned into a
2939 Debian package, and so there is only one
"debianisation"
2940 of it and therefore no revision indication is required.
2944 It is conventional to restart the
2945 <var>debian_revision
</var> at
<tt>1</tt> each time the
2946 <var>upstream_version
</var> is increased.
2950 The package management system will break the version
2951 number apart at the last hyphen in the string (if there
2952 is one) to determine the
<var>upstream_version
</var> and
2953 <var>debian_revision
</var>. The absence of a
2954 <var>debian_revision
</var> is equivalent to a
2955 <var>debian_revision
</var> of
<tt>0</tt>.
2962 When comparing two version numbers, first the
<var>epoch
</var>
2963 of each are compared, then the
<var>upstream_version
</var> if
2964 <var>epoch
</var> is equal, and then
<var>debian_revision
</var>
2965 if
<var>upstream_version
</var> is also equal.
2966 <var>epoch
</var> is compared numerically. The
2967 <var>upstream_version
</var> and
<var>debian_revision
</var>
2968 parts are compared by the package management system using the
2969 following algorithm:
2973 The strings are compared from left to right.
2977 First the initial part of each string consisting entirely of
2978 non-digit characters is determined. These two parts (one of
2979 which may be empty) are compared lexically. If a difference
2980 is found it is returned. The lexical comparison is a
2981 comparison of ASCII values modified so that all the letters
2982 sort earlier than all the non-letters and so that a tilde
2983 sorts before anything, even the end of a part. For example,
2984 the following parts are in sorted order from earliest to
2985 latest:
<tt>~~
</tt>,
<tt>~~a
</tt>,
<tt>~
</tt>, the empty part,
2986 <tt>a
</tt>.
<footnote>
2987 One common use of
<tt>~
</tt> is for upstream pre-releases.
2988 For example,
<tt>1.0~beta1~svn1245
</tt> sorts earlier than
2989 <tt>1.0~beta1
</tt>, which sorts earlier than
<tt>1.0</tt>.
2994 Then the initial part of the remainder of each string which
2995 consists entirely of digit characters is determined. The
2996 numerical values of these two parts are compared, and any
2997 difference found is returned as the result of the comparison.
2998 For these purposes an empty string (which can only occur at
2999 the end of one or both version strings being compared) counts
3004 These two steps (comparing and removing initial non-digit
3005 strings and initial digit strings) are repeated until a
3006 difference is found or both strings are exhausted.
3010 Note that the purpose of epochs is to allow us to leave behind
3011 mistakes in version numbering, and to cope with situations
3012 where the version numbering scheme changes. It is
3013 <em>not
</em> intended to cope with version numbers containing
3014 strings of letters which the package management system cannot
3015 interpret (such as
<tt>ALPHA
</tt> or
<tt>pre-
</tt>), or with
3016 silly orderings (the author of this manual has heard of a
3017 package whose versions went
<tt>1.1</tt>,
<tt>1.2</tt>,
3018 <tt>1.3</tt>,
<tt>1</tt>,
<tt>2.1</tt>,
<tt>2.2</tt>,
3019 <tt>2</tt> and so forth).
3023 <sect1 id=
"f-Description">
3024 <heading><tt>Description
</tt></heading>
3027 In a source or binary control file, the
<tt>Description
</tt>
3028 field contains a description of the binary package, consisting
3029 of two parts, the synopsis or the short description, and the
3030 long description. The field's format is as follows:
3035 Description:
<single line synopsis
>
3036 <extended description over several lines
>
3041 The lines in the extended description can have these formats:
3047 Those starting with a single space are part of a paragraph.
3048 Successive lines of this form will be word-wrapped when
3049 displayed. The leading space will usually be stripped off.
3053 Those starting with two or more spaces. These will be
3054 displayed verbatim. If the display cannot be panned
3055 horizontally, the displaying program will line wrap them
"hard"
3056 (i.e., without taking account of word breaks). If it can they
3057 will be allowed to trail off to the right. None, one or two
3058 initial spaces may be deleted, but the number of spaces
3059 deleted from each line will be the same (so that you can have
3060 indenting work correctly, for example).
3064 Those containing a single space followed by a single full stop
3065 character. These are rendered as blank lines. This is the
3066 <em>only
</em> way to get a blank line
<footnote>
3067 Completely empty lines will not be rendered as blank lines.
3068 Instead, they will cause the parser to think you're starting
3069 a whole new record in the control file, and will therefore
3070 likely abort with an error.
3075 Those containing a space, a full stop and some more characters.
3076 These are for future expansion. Do not use them.
3082 Do not use tab characters. Their effect is not predictable.
3086 See
<ref id=
"descriptions"> for further information on this.
3090 In a
<file>.changes
</file> file, the
<tt>Description
</tt> field
3091 contains a summary of the descriptions for the packages being
3096 The part of the field before the first newline is empty;
3097 thereafter each line has the name of a binary package and
3098 the summary description line from that binary package.
3099 Each line is indented by one space.
3104 <sect1 id=
"f-Distribution">
3105 <heading><tt>Distribution
</tt></heading>
3108 In a
<file>.changes
</file> file or parsed changelog output
3109 this contains the (space-separated) name(s) of the
3110 distribution(s) where this version of the package should
3111 be installed. Valid distributions are determined by the
3112 archive maintainers.
<footnote>
3113 Current distribution names are:
3114 <taglist compact=
"compact">
3115 <tag><em>stable
</em></tag>
3117 This is the current
"released" version of Debian
3118 GNU/Linux. Once the distribution is
3119 <em>stable
</em> only security fixes and other
3120 major bug fixes are allowed. When changes are
3121 made to this distribution, the release number is
3122 increased (for example:
2.2r1 becomes
2.2r2 then
3126 <tag><em>unstable
</em></tag>
3128 This distribution value refers to the
3129 <em>developmental
</em> part of the Debian
3130 distribution tree. New packages, new upstream
3131 versions of packages and bug fixes go into the
3132 <em>unstable
</em> directory tree. Download from
3133 this distribution at your own risk.
3136 <tag><em>testing
</em></tag>
3138 This distribution value refers to the
3139 <em>testing
</em> part of the Debian distribution
3140 tree. It receives its packages from the
3141 unstable distribution after a short time lag to
3142 ensure that there are no major issues with the
3143 unstable packages. It is less prone to breakage
3144 than unstable, but still risky. It is not
3145 possible to upload packages directly to
3149 <tag><em>frozen
</em></tag>
3151 From time to time, the
<em>testing
</em>
3152 distribution enters a state of
"code-freeze" in
3153 anticipation of release as a
<em>stable
</em>
3154 version. During this period of testing only
3155 fixes for existing or newly-discovered bugs will
3156 be allowed. The exact details of this stage are
3157 determined by the Release Manager.
3160 <tag><em>experimental
</em></tag>
3162 The packages with this distribution value are
3163 deemed by their maintainers to be high
3164 risk. Oftentimes they represent early beta or
3165 developmental packages from various sources that
3166 the maintainers want people to try, but are not
3167 ready to be a part of the other parts of the
3168 Debian distribution tree. Download at your own
3174 You should list
<em>all
</em> distributions that the
3175 package should be installed into.
3179 More information is available in the Debian Developer's
3180 Reference, section
"The Debian archive".
3187 <heading><tt>Date
</tt></heading>
3190 This field includes the date the package was built or last edited.
3194 The value of this field is usually extracted from the
3195 <file>debian/changelog
</file> file - see
3196 <ref id=
"dpkgchangelog">).
3200 <sect1 id=
"f-Format">
3201 <heading><tt>Format
</tt></heading>
3204 This field specifies a format revision for the file.
3205 The most current format described in the Policy Manual
3206 is version
<strong>1.5</strong>. The syntax of the
3207 format value is the same as that of a package version
3208 number except that no epoch or Debian revision is allowed
3209 - see
<ref id=
"f-Version">.
3213 <sect1 id=
"f-Urgency">
3214 <heading><tt>Urgency
</tt></heading>
3217 This is a description of how important it is to upgrade to
3218 this version from previous ones. It consists of a single
3219 keyword taking one of the values
<tt>low
</tt>,
3220 <tt>medium
</tt>,
<tt>high
</tt>,
<tt>emergency
</tt>, or
3221 <tt>critical
</tt><footnote>
3222 Other urgency values are supported with configuration
3223 changes in the archive software but are not used in Debian.
3224 The urgency affects how quickly a package will be considered
3225 for inclusion into the
<tt>testing
</tt> distribution and
3226 gives an indication of the importance of any fixes included
3227 in the upload.
<tt>Emergency
</tt> and
<tt>critical
</tt> are
3228 treated as synonymous.
3229 </footnote> (not case-sensitive) followed by an optional
3230 commentary (separated by a space) which is usually in
3231 parentheses. For example:
3234 Urgency: low (HIGH for users of diversions)
3240 The value of this field is usually extracted from the
3241 <file>debian/changelog
</file> file - see
3242 <ref id=
"dpkgchangelog">.
3246 <sect1 id=
"f-Changes">
3247 <heading><tt>Changes
</tt></heading>
3250 This field contains the human-readable changes data, describing
3251 the differences between the last version and the current one.
3255 There should be nothing in this field before the first
3256 newline; all the subsequent lines must be indented by at
3257 least one space; blank lines must be represented by a line
3258 consisting only of a space and a full stop.
3262 The value of this field is usually extracted from the
3263 <file>debian/changelog
</file> file - see
3264 <ref id=
"dpkgchangelog">).
3268 Each version's change information should be preceded by a
3269 "title" line giving at least the version, distribution(s)
3270 and urgency, in a human-readable way.
3274 If data from several versions is being returned the entry
3275 for the most recent version should be returned first, and
3276 entries should be separated by the representation of a
3277 blank line (the
"title" line may also be followed by the
3278 representation of blank line).
3282 <sect1 id=
"f-Binary">
3283 <heading><tt>Binary
</tt></heading>
3286 This field is a list of binary packages.
3290 When it appears in the
<file>.dsc
</file> file it is the list
3291 of binary packages which a source package can produce. It
3292 does not necessarily produce all of these binary packages
3293 for every architecture. The source control file doesn't
3294 contain details of which architectures are appropriate for
3295 which of the binary packages.
3299 When it appears in a
<file>.changes
</file> file it lists the
3300 names of the binary packages actually being uploaded.
3304 The syntax is a list of binary packages separated by
3306 A space after each comma is conventional.
3307 </footnote>. Currently the packages must be separated using
3308 only spaces in the
<file>.changes
</file> file.
3312 <sect1 id=
"f-Installed-Size">
3313 <heading><tt>Installed-Size
</tt></heading>
3316 This field appears in the control files of binary
3317 packages, and in the
<file>Packages
</file> files. It gives
3318 the total amount of disk space required to install the
3323 The disk space is represented in kilobytes as a simple
3328 <sect1 id=
"f-Files">
3329 <heading><tt>Files
</tt></heading>
3332 This field contains a list of files with information about
3333 each one. The exact information and syntax varies with
3334 the context. In all cases the part of the field
3335 contents on the same line as the field name is empty. The
3336 remainder of the field is one line per file, each line
3337 being indented by one space and containing a number of
3338 sub-fields separated by spaces.
3342 In the
<file>.dsc
</file> file, each line contains the MD5
3343 checksum, size and filename of the tar file and (if applicable)
3344 diff file which make up the remainder of the source
3346 That is, the parts which are not the
<tt>.dsc
</tt>.
3348 The exact forms of the filenames are described
3349 in
<ref id=
"pkg-sourcearchives">.
3353 In the
<file>.changes
</file> file this contains one line per
3354 file being uploaded. Each line contains the MD5 checksum,
3355 size, section and priority and the filename.
3356 The
<qref id=
"f-Section">section
</qref>
3357 and
<qref id=
"f-Priority">priority
</qref>
3358 are the values of the corresponding fields in
3359 the main source control file. If no section or priority is
3360 specified then
<tt>-
</tt> should be used, though section
3361 and priority values must be specified for new packages to
3362 be installed properly.
3366 The special value
<tt>byhand
</tt> for the section in a
3367 <tt>.changes
</tt> file indicates that the file in question
3368 is not an ordinary package file and must by installed by
3369 hand by the distribution maintainers. If the section is
3370 <tt>byhand
</tt> the priority should be
<tt>-
</tt>.
3374 If a new Debian revision of a package is being shipped and
3375 no new original source archive is being distributed the
3376 <tt>.dsc
</tt> must still contain the
<tt>Files
</tt> field
3377 entry for the original source archive
3378 <file><var>package
</var>-
<var>upstream-version
</var>.orig.tar.gz
</file>,
3379 but the
<file>.changes
</file> file should leave it out. In
3380 this case the original source archive on the distribution
3381 site must match exactly, byte-for-byte, the original
3382 source archive which was used to generate the
3383 <file>.dsc
</file> file and diff which are being uploaded.
</p>
3386 <sect1 id=
"f-Closes">
3387 <heading><tt>Closes
</tt></heading>
3390 A space-separated list of bug report numbers that the upload
3391 governed by the .changes file closes.
3395 <sect1 id=
"f-Homepage">
3396 <heading><tt>Homepage
</tt></heading>
3399 The URL of the web site for this package, preferably (when
3400 applicable) the site from which the original source can be
3401 obtained and any additional upstream documentation or
3402 information may be found. The content of this field is a
3403 simple URL without any surrounding characters such as
3411 <heading>User-defined fields
</heading>
3414 Additional user-defined fields may be added to the
3415 source package control file. Such fields will be
3416 ignored, and not copied to (for example) binary or
3417 source package control files or upload control files.
3421 If you wish to add additional unsupported fields to
3422 these output files you should use the mechanism
3427 Fields in the main source control information file with
3428 names starting
<tt>X
</tt>, followed by one or more of
3429 the letters
<tt>BCS
</tt> and a hyphen
<tt>-
</tt>, will
3430 be copied to the output files. Only the part of the
3431 field name after the hyphen will be used in the output
3432 file. Where the letter
<tt>B
</tt> is used the field
3433 will appear in binary package control files, where the
3434 letter
<tt>S
</tt> is used in source package control
3435 files and where
<tt>C
</tt> is used in upload control
3436 (
<tt>.changes
</tt>) files.
3440 For example, if the main source information control file
3443 XBS-Comment: I stand between the candle and the star.
3445 then the binary and source package control files will contain the
3448 Comment: I stand between the candle and the star.
3457 <chapt id=
"maintainerscripts">
3458 <heading>Package maintainer scripts and installation procedure
</heading>
3461 <heading>Introduction to package maintainer scripts
</heading>
3464 It is possible to supply scripts as part of a package which
3465 the package management system will run for you when your
3466 package is installed, upgraded or removed.
3470 These scripts are the files
<prgn>preinst
</prgn>,
3471 <prgn>postinst
</prgn>,
<prgn>prerm
</prgn> and
3472 <prgn>postrm
</prgn> in the control area of the package.
3473 They must be proper executable files; if they are scripts
3474 (which is recommended), they must start with the usual
3475 <tt>#!
</tt> convention. They should be readable and
3476 executable by anyone, and must not be world-writable.
3480 The package management system looks at the exit status from
3481 these scripts. It is important that they exit with a
3482 non-zero status if there is an error, so that the package
3483 management system can stop its processing. For shell
3484 scripts this means that you
<em>almost always
</em> need to
3485 use
<tt>set -e
</tt> (this is usually true when writing shell
3486 scripts, in fact). It is also important, of course, that
3487 they exit with a zero status if everything went well.
3491 Additionally, packages interacting with users using
3492 <tt>debconf
</tt> in the
<prgn>postinst
</prgn> script should
3493 install a
<prgn>config
</prgn> script in the control area,
3494 see
<ref id=
"maintscriptprompt"> for details.
3498 When a package is upgraded a combination of the scripts from
3499 the old and new packages is called during the upgrade
3500 procedure. If your scripts are going to be at all
3501 complicated you need to be aware of this, and may need to
3502 check the arguments to your scripts.
3506 Broadly speaking the
<prgn>preinst
</prgn> is called before
3507 (a particular version of) a package is installed, and the
3508 <prgn>postinst
</prgn> afterwards; the
<prgn>prerm
</prgn>
3509 before (a version of) a package is removed and the
3510 <prgn>postrm
</prgn> afterwards.
3514 Programs called from maintainer scripts should not normally
3515 have a path prepended to them. Before installation is
3516 started, the package management system checks to see if the
3517 programs
<prgn>ldconfig
</prgn>,
3518 <prgn>start-stop-daemon
</prgn>,
<prgn>install-info
</prgn>,
3519 and
<prgn>update-rc.d
</prgn> can be found via the
3520 <tt>PATH
</tt> environment variable. Those programs, and any
3521 other program that one would expect to be in the
3522 <tt>PATH
</tt>, should thus be invoked without an absolute
3523 pathname. Maintainer scripts should also not reset the
3524 <tt>PATH
</tt>, though they might choose to modify it by
3525 prepending or appending package-specific directories. These
3526 considerations really apply to all shell scripts.
</p>
3529 <sect id=
"idempotency">
3530 <heading>Maintainer scripts idempotency
</heading>
3533 It is necessary for the error recovery procedures that the
3534 scripts be idempotent. This means that if it is run
3535 successfully, and then it is called again, it doesn't bomb
3536 out or cause any harm, but just ensures that everything is
3537 the way it ought to be. If the first call failed, or
3538 aborted half way through for some reason, the second call
3539 should merely do the things that were left undone the first
3540 time, if any, and exit with a success status if everything
3542 This is so that if an error occurs, the user interrupts
3543 <prgn>dpkg
</prgn> or some other unforeseen circumstance
3544 happens you don't leave the user with a badly-broken
3545 package when
<prgn>dpkg
</prgn> attempts to repeat the
3551 <sect id=
"controllingterminal">
3552 <heading>Controlling terminal for maintainer scripts
</heading>
3555 The maintainer scripts are guaranteed to run with a
3556 controlling terminal and can interact with the user.
3557 Because these scripts may be executed with standard output
3558 redirected into a pipe for logging purposes, Perl scripts
3559 should set unbuffered output by setting
<tt>$|=
1</tt> so
3560 that the output is printed immediately rather than being
3564 <sect id=
"exitstatus">
3565 <heading>Exit status
</heading>
3568 Each script must return a zero exit status for
3569 success, or a nonzero one for failure, since the package
3570 management system looks for the exit status of these scripts
3571 and determines what action to take next based on that datum.
3575 <sect id=
"mscriptsinstact"><heading>Summary of ways maintainer
3580 <list compact=
"compact">
3582 <var>new-preinst
</var> <tt>install
</tt>
3585 <var>new-preinst
</var> <tt>install
</tt> <var>old-version
</var>
3588 <var>new-preinst
</var> <tt>upgrade
</tt> <var>old-version
</var>
3591 <var>old-preinst
</var> <tt>abort-upgrade
</tt>
3592 <var>new-version
</var>
3597 <list compact=
"compact">
3599 <var>postinst
</var> <tt>configure
</tt>
3600 <var>most-recently-configured-version
</var>
3603 <var>old-postinst
</var> <tt>abort-upgrade
</tt>
3604 <var>new-version
</var>
3607 <var>conflictor's-postinst
</var> <tt>abort-remove
</tt>
3608 <tt>in-favour
</tt> <var>package
</var>
3609 <var>new-version
</var>
3612 <var>postinst
</var> <tt>abort-remove
</tt>
3615 <var>deconfigured's-postinst
</var>
3616 <tt>abort-deconfigure
</tt> <tt>in-favour
</tt>
3617 <var>failed-install-package
</var> <var>version
</var>
3618 [
<tt>removing
</tt> <var>conflicting-package
</var>
3624 <list compact=
"compact">
3626 <var>prerm
</var> <tt>remove
</tt>
3629 <var>old-prerm
</var> <tt>upgrade
</tt>
3630 <var>new-version
</var>
3633 <var>new-prerm
</var> <tt>failed-upgrade
</tt>
3634 <var>old-version
</var>
3637 <var>conflictor's-prerm
</var> <tt>remove
</tt>
3638 <tt>in-favour
</tt> <var>package
</var>
3639 <var>new-version
</var>
3642 <var>deconfigured's-prerm
</var> <tt>deconfigure
</tt>
3643 <tt>in-favour
</tt> <var>package-being-installed
</var>
3644 <var>version
</var> [
<tt>removing
</tt>
3645 <var>conflicting-package
</var>
3651 <list compact=
"compact">
3653 <var>postrm
</var> <tt>remove
</tt>
3656 <var>postrm
</var> <tt>purge
</tt>
3659 <var>old-postrm
</var> <tt>upgrade
</tt>
3660 <var>new-version
</var>
3663 <var>new-postrm
</var> <tt>failed-upgrade
</tt>
3664 <var>old-version
</var>
3667 <var>new-postrm
</var> <tt>abort-install
</tt>
3670 <var>new-postrm
</var> <tt>abort-install
</tt>
3671 <var>old-version
</var>
3674 <var>new-postrm
</var> <tt>abort-upgrade
</tt>
3675 <var>old-version
</var>
3678 <var>disappearer's-postrm
</var> <tt>disappear
</tt>
3679 <var>overwriter
</var>
3680 <var>overwriter-version
</var>
3686 <sect id=
"unpackphase">
3687 <heading>Details of unpack phase of installation or upgrade
</heading>
3690 The procedure on installation/upgrade/overwrite/disappear
3691 (i.e., when running
<tt>dpkg --unpack
</tt>, or the unpack
3692 stage of
<tt>dpkg --install
</tt>) is as follows. In each
3693 case, if a major error occurs (unless listed below) the
3694 actions are, in general, run backwards - this means that the
3695 maintainer scripts are run with different arguments in
3696 reverse order. These are the
"error unwind" calls listed
3703 If a version of the package is already installed, call
3704 <example compact=
"compact">
3705 <var>old-prerm
</var> upgrade
<var>new-version
</var>
3709 If the script runs but exits with a non-zero
3710 exit status,
<prgn>dpkg
</prgn> will attempt:
3711 <example compact=
"compact">
3712 <var>new-prerm
</var> failed-upgrade
<var>old-version
</var>
3714 If this works, the upgrade continues. If this
3715 does not work, the error unwind:
3716 <example compact=
"compact">
3717 <var>old-postinst
</var> abort-upgrade
<var>new-version
</var>
3719 If this works, then the old-version is
3720 "Installed", if not, the old version is in a
3721 "Failed-Config" state.
3727 If a
"conflicting" package is being removed at the same time,
3728 or if any package will be broken (due to
<tt>Breaks
</tt>):
3731 If
<tt>--auto-deconfigure
</tt> is
3732 specified, call, for each package to be deconfigured
3733 due to
<tt>Breaks
</tt>:
3734 <example compact=
"compact">
3735 <var>deconfigured's-prerm
</var> deconfigure \
3736 in-favour
<var>package-being-installed
</var> <var>version
</var>
3739 <example compact=
"compact">
3740 <var>deconfigured's-postinst
</var> abort-deconfigure \
3741 in-favour
<var>package-being-installed-but-failed
</var> <var>version
</var>
3743 The deconfigured packages are marked as
3744 requiring configuration, so that if
3745 <tt>--install
</tt> is used they will be
3746 configured again if possible.
3749 If any packages depended on a conflicting
3750 package being removed and
<tt>--auto-deconfigure
</tt> is
3751 specified, call, for each such package:
3752 <example compact=
"compact">
3753 <var>deconfigured's-prerm
</var> deconfigure \
3754 in-favour
<var>package-being-installed
</var> <var>version
</var> \
3755 removing
<var>conflicting-package
</var> <var>version
</var>
3758 <example compact=
"compact">
3759 <var>deconfigured's-postinst
</var> abort-deconfigure \
3760 in-favour
<var>package-being-installed-but-failed
</var> <var>version
</var> \
3761 removing
<var>conflicting-package
</var> <var>version
</var>
3763 The deconfigured packages are marked as
3764 requiring configuration, so that if
3765 <tt>--install
</tt> is used they will be
3766 configured again if possible.
3769 To prepare for removal of each conflicting package, call:
3770 <example compact=
"compact">
3771 <var>conflictor's-prerm
</var> remove \
3772 in-favour
<var>package
</var> <var>new-version
</var>
3775 <example compact=
"compact">
3776 <var>conflictor's-postinst
</var> abort-remove \
3777 in-favour
<var>package
</var> <var>new-version
</var>
3786 If the package is being upgraded, call:
3787 <example compact=
"compact">
3788 <var>new-preinst
</var> upgrade
<var>old-version
</var>
3790 If this fails, we call:
3792 <var>new-postrm
</var> abort-upgrade
<var>old-version
</var>
3799 <var>old-postinst
</var> abort-upgrade
<var>new-version
</var>
3801 is called. If this works, then the old version
3802 is in an
"Installed" state, or else it is left
3803 in an
"Unpacked" state.
3808 If it fails, then the old version is left
3809 in an
"Half-Installed" state.
3816 Otherwise, if the package had some configuration
3817 files from a previous version installed (i.e., it
3818 is in the
"configuration files only" state):
3819 <example compact=
"compact">
3820 <var>new-preinst
</var> install
<var>old-version
</var>
3824 <var>new-postrm
</var> abort-install
<var>old-version
</var>
3826 If this fails, the package is left in a
3827 "Half-Installed" state, which requires a
3828 reinstall. If it works, the packages is left in
3829 a
"Config Files" state.
3832 Otherwise (i.e., the package was completely purged):
3833 <example compact=
"compact">
3834 <var>new-preinst
</var> install
3837 <example compact=
"compact">
3838 <var>new-postrm
</var> abort-install
3840 If the error-unwind fails, the package is in a
3841 "Half Installed" phase, and requires a
3842 reinstall. If the error unwind works, the
3843 package is in a not installed state.
3850 The new package's files are unpacked, overwriting any
3851 that may be on the system already, for example any
3852 from the old version of the same package or from
3853 another package. Backups of the old files are kept
3854 temporarily, and if anything goes wrong the package
3855 management system will attempt to put them back as
3856 part of the error unwind.
3860 It is an error for a package to contain files which
3861 are on the system in another package, unless
3862 <tt>Replaces
</tt> is used (see
<ref id=
"replaces">).
3864 The following paragraph is not currently the case:
3865 Currently the <tt>- - force-overwrite</tt> flag is
3866 enabled, downgrading it to a warning, but this may not
3872 It is a more serious error for a package to contain a
3873 plain file or other kind of non-directory where another
3874 package has a directory (again, unless
3875 <tt>Replaces
</tt> is used). This error can be
3876 overridden if desired using
3877 <tt>--force-overwrite-dir
</tt>, but this is not
3882 Packages which overwrite each other's files produce
3883 behavior which, though deterministic, is hard for the
3884 system administrator to understand. It can easily
3885 lead to
"missing" programs if, for example, a package
3886 is installed which overwrites a file from another
3887 package, and is then removed again.
<footnote>
3888 Part of the problem is due to what is arguably a
3889 bug in
<prgn>dpkg
</prgn>.
3894 A directory will never be replaced by a symbolic link
3895 to a directory or vice versa; instead, the existing
3896 state (symlink or not) will be left alone and
3897 <prgn>dpkg
</prgn> will follow the symlink if there is
3906 If the package is being upgraded, call
3907 <example compact=
"compact">
3908 <var>old-postrm
</var> upgrade
<var>new-version
</var>
3912 If this fails,
<prgn>dpkg
</prgn> will attempt:
3913 <example compact=
"compact">
3914 <var>new-postrm
</var> failed-upgrade
<var>old-version
</var>
3916 If this works, installation continues. If not,
3918 <example compact=
"compact">
3919 <var>old-preinst
</var> abort-upgrade
<var>new-version
</var>
3921 If this fails, the old version is left in an
3922 "Half Installed" state. If it works, dpkg now
3924 <example compact=
"compact">
3925 <var>new-postrm
</var> abort-upgrade
<var>old-version
</var>
3927 If this fails, the old version is left in an
3928 "Half Installed" state. If it works, dpkg now
3930 <example compact=
"compact">
3931 <var>old-postinst
</var> abort-upgrade
<var>new-version
</var>
3933 If this fails, the old version is in an
3940 This is the point of no return - if
3941 <prgn>dpkg
</prgn> gets this far, it won't back off
3942 past this point if an error occurs. This will
3943 leave the package in a fairly bad state, which
3944 will require a successful re-installation to clear
3945 up, but it's when
<prgn>dpkg
</prgn> starts doing
3946 things that are irreversible.
3951 Any files which were in the old version of the package
3952 but not in the new are removed.
3956 The new file list replaces the old.
3960 The new maintainer scripts replace the old.
3964 Any packages all of whose files have been overwritten
3965 during the installation, and which aren't required for
3966 dependencies, are considered to have been removed.
3967 For each such package
3970 <prgn>dpkg
</prgn> calls:
3971 <example compact=
"compact">
3972 <var>disappearer's-postrm
</var> disappear \
3973 <var>overwriter
</var> <var>overwriter-version
</var>
3977 The package's maintainer scripts are removed.
3980 It is noted in the status database as being in a
3981 sane state, namely not installed (any conffiles
3982 it may have are ignored, rather than being
3983 removed by
<prgn>dpkg
</prgn>). Note that
3984 disappearing packages do not have their prerm
3985 called, because
<prgn>dpkg
</prgn> doesn't know
3986 in advance that the package is going to
3993 Any files in the package we're unpacking that are also
3994 listed in the file lists of other packages are removed
3995 from those lists. (This will lobotomize the file list
3996 of the
"conflicting" package if there is one.)
4000 The backup files made during installation, above, are
4006 The new package's status is now sane, and recorded as
4011 Here is another point of no return - if the
4012 conflicting package's removal fails we do not unwind
4013 the rest of the installation; the conflicting package
4014 is left in a half-removed limbo.
4019 If there was a conflicting package we go and do the
4020 removal actions (described below), starting with the
4021 removal of the conflicting package's files (any that
4022 are also in the package being installed have already
4023 been removed from the conflicting package's file list,
4024 and so do not get removed now).
4030 <sect id=
"configdetails"><heading>Details of configuration
</heading>
4033 When we configure a package (this happens with
<tt>dpkg
4034 --install
</tt> and
<tt>dpkg --configure
</tt>), we first
4035 update any
<tt>conffile
</tt>s and then call:
4036 <example compact=
"compact">
4037 <var>postinst
</var> configure
<var>most-recently-configured-version
</var>
4042 No attempt is made to unwind after errors during
4043 configuration. If the configuration fails, the package is in
4044 a
"Failed Config" state, and an error message is generated.
4048 If there is no most recently configured version
4049 <prgn>dpkg
</prgn> will pass a null argument.
4052 Historical note: Truly ancient (pre-
1997) versions of
4053 <prgn>dpkg
</prgn> passed
<tt><unknown
></tt>
4054 (including the angle brackets) in this case. Even older
4055 ones did not pass a second argument at all, under any
4056 circumstance. Note that upgrades using such an old dpkg
4057 version are unlikely to work for other reasons, even if
4058 this old argument behavior is handled by your postinst script.
4064 <sect id=
"removedetails"><heading>Details of removal and/or
4065 configuration purging
</heading>
4071 <example compact=
"compact">
4072 <var>prerm
</var> remove
4076 If prerm fails during replacement due to conflict
4078 <var>conflictor's-postinst
</var> abort-remove \
4079 in-favour
<var>package
</var> <var>new-version
</var>
4083 <var>postinst
</var> abort-remove
4087 If this fails, the package is in a
"Failed-Config"
4088 state, or else it remains
"Installed".
4092 The package's files are removed (except
<tt>conffile
</tt>s).
4095 <example compact=
"compact">
4096 <var>postrm
</var> remove
4100 If it fails, there's no error unwind, and the package is in
4101 an
"Half-Installed" state.
4106 All the maintainer scripts except the
<prgn>postrm
</prgn>
4111 If we aren't purging the package we stop here. Note
4112 that packages which have no
<prgn>postrm
</prgn> and no
4113 <tt>conffile
</tt>s are automatically purged when
4114 removed, as there is no difference except for the
4115 <prgn>dpkg
</prgn> status.
4119 The
<tt>conffile
</tt>s and any backup files
4120 (
<tt>~
</tt>-files,
<tt>#*#
</tt> files,
4121 <tt>%
</tt>-files,
<tt>.dpkg-{old,new,tmp}
</tt>, etc.)
4126 <example compact=
"compact">
4127 <var>postrm
</var> purge
4131 If this fails, the package remains in a
"Config-Files"
4136 The package's file list is removed.
4145 <chapt id=
"relationships">
4146 <heading>Declaring relationships between packages
</heading>
4148 <sect id=
"depsyntax">
4149 <heading>Syntax of relationship fields
</heading>
4152 These fields all have a uniform syntax. They are a list of
4153 package names separated by commas.
4157 In the
<tt>Depends
</tt>,
<tt>Recommends
</tt>,
4158 <tt>Suggests
</tt>,
<tt>Pre-Depends
</tt>,
4159 <tt>Build-Depends
</tt> and
<tt>Build-Depends-Indep
</tt>
4160 control file fields of the package, which declare
4161 dependencies on other packages, the package names listed may
4162 also include lists of alternative package names, separated
4163 by vertical bar (pipe) symbols
<tt>|
</tt>. In such a case,
4164 if any one of the alternative packages is installed, that
4165 part of the dependency is considered to be satisfied.
4169 All of the fields except for
<tt>Provides
</tt> may restrict
4170 their applicability to particular versions of each named
4171 package. This is done in parentheses after each individual
4172 package name; the parentheses should contain a relation from
4173 the list below followed by a version number, in the format
4174 described in
<ref id=
"f-Version">.
4178 The relations allowed are
<tt><<</tt>,
<tt><=
</tt>,
4179 <tt>=
</tt>,
<tt>>=
</tt> and
<tt>>></tt> for
4180 strictly earlier, earlier or equal, exactly equal, later or
4181 equal and strictly later, respectively. The deprecated
4182 forms
<tt><</tt> and
<tt>></tt> were used to mean
4183 earlier/later or equal, rather than strictly earlier/later,
4184 so they should not appear in new packages (though
4185 <prgn>dpkg
</prgn> still supports them).
4189 Whitespace may appear at any point in the version
4190 specification subject to the rules in
<ref
4191 id=
"controlsyntax">, and must appear where it's necessary to
4192 disambiguate; it is not otherwise significant. All of the
4193 relationship fields may span multiple lines. For
4194 consistency and in case of future changes to
4195 <prgn>dpkg
</prgn> it is recommended that a single space be
4196 used after a version relationship and before a version
4197 number; it is also conventional to put a single space after
4198 each comma, on either side of each vertical bar, and before
4199 each open parenthesis. When wrapping a relationship field, it
4200 is conventional to do so after a comma and before the space
4201 following that comma.
4205 For example, a list of dependencies might appear as:
4206 <example compact=
"compact">
4209 Depends: libc6 (
>=
2.2.1), exim | mail-transport-agent
4214 All fields that specify build-time relationships
4215 (
<tt>Build-Depends
</tt>,
<tt>Build-Depends-Indep
</tt>,
4216 <tt>Build-Conflicts
</tt> and
<tt>Build-Conflicts-Indep
</tt>)
4217 may be restricted to a certain set of architectures. This
4218 is indicated in brackets after each individual package name and
4219 the optional version specification. The brackets enclose a
4220 list of Debian architecture names separated by whitespace.
4221 Exclamation marks may be prepended to each of the names.
4222 (It is not permitted for some names to be prepended with
4223 exclamation marks while others aren't.) If the current Debian
4224 host architecture is not in this list and there are no
4225 exclamation marks in the list, or it is in the list with a
4226 prepended exclamation mark, the package name and the
4227 associated version specification are ignored completely for
4228 the purposes of defining the relationships.
4233 <example compact=
"compact">
4235 Build-Depends-Indep: texinfo
4236 Build-Depends: kernel-headers-
2.2.10 [!hurd-i386],
4237 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4239 requires
<tt>kernel-headers-
2.2.10</tt> on all architectures
4240 other than hurd-i386 and requires
<tt>hurd-dev
</tt> and
4241 <tt>gnumach-dev
</tt> only on hurd-i386.
4245 If the architecture-restricted dependency is part of a set of
4246 alternatives using
<tt>|
</tt>, that alternative is ignored
4247 completely on architectures that do not match the restriction.
4249 <example compact=
"compact">
4250 Build-Depends: foo [!i386] | bar [!amd64]
4252 is equivalent to
<tt>bar
</tt> on the i386 architecture, to
4253 <tt>foo
</tt> on the amd64 architecture, and to
<tt>foo |
4254 bar
</tt> on all other architectures.
4258 Note that the binary package relationship fields such as
4259 <tt>Depends
</tt> appear in one of the binary package
4260 sections of the control file, whereas the build-time
4261 relationships such as
<tt>Build-Depends
</tt> appear in the
4262 source package section of the control file (which is the
4267 <sect id=
"binarydeps">
4268 <heading>Binary Dependencies -
<tt>Depends
</tt>,
4269 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
<tt>Enhances
</tt>,
4270 <tt>Pre-Depends
</tt>
4274 Packages can declare in their control file that they have
4275 certain relationships to other packages - for example, that
4276 they may not be installed at the same time as certain other
4277 packages, and/or that they depend on the presence of others.
4281 This is done using the
<tt>Depends
</tt>,
<tt>Pre-Depends
</tt>,
4282 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
<tt>Enhances
</tt>,
4283 <tt>Breaks
</tt> and
<tt>Conflicts
</tt> control file fields.
4287 These seven fields are used to declare a dependency
4288 relationship by one package on another. Except for
4289 <tt>Enhances
</tt> and
<tt>Breaks
</tt>, they appear in the
4290 depending (binary) package's control file.
4291 (
<tt>Enhances
</tt> appears in the recommending package's
4292 control file, and
<tt>Breaks
</tt> appears in the version of
4293 depended-on package which causes the named package to
4298 A
<tt>Depends
</tt> field takes effect
<em>only
</em> when a
4299 package is to be configured. It does not prevent a package
4300 being on the system in an unconfigured state while its
4301 dependencies are unsatisfied, and it is possible to replace
4302 a package whose dependencies are satisfied and which is
4303 properly installed with a different version whose
4304 dependencies are not and cannot be satisfied; when this is
4305 done the depending package will be left unconfigured (since
4306 attempts to configure it will give errors) and will not
4307 function properly. If it is necessary, a
4308 <tt>Pre-Depends
</tt> field can be used, which has a partial
4309 effect even when a package is being unpacked, as explained
4310 in detail below. (The other three dependency fields,
4311 <tt>Recommends
</tt>,
<tt>Suggests
</tt> and
4312 <tt>Enhances
</tt>, are only used by the various front-ends
4313 to
<prgn>dpkg
</prgn> such as
<prgn>apt-get
</prgn>,
4314 <prgn>aptitude
</prgn>, and
<prgn>dselect
</prgn>.)
4318 For this reason packages in an installation run are usually
4319 all unpacked first and all configured later; this gives
4320 later versions of packages with dependencies on later
4321 versions of other packages the opportunity to have their
4322 dependencies satisfied.
4326 In case of circular dependencies, since installation or
4327 removal order honoring the dependency order can't be
4328 established, dependency loops are broken at some point
4329 (based on rules below), and some packages may not be able to
4330 rely on their dependencies being present when being
4331 installed or removed, depending on which side of the break
4332 of the circular dependency loop they happen to be on. If one
4333 of the packages in the loop has no postinst script, then the
4334 cycle will be broken at that package, so as to ensure that
4335 all postinst scripts run with the dependencies properly
4336 configured if this is possible. Otherwise the breaking point
4341 The
<tt>Depends
</tt> field thus allows package maintainers
4342 to impose an order in which packages should be configured.
4346 The meaning of the five dependency fields is as follows:
4348 <tag><tt>Depends
</tt></tag>
4351 This declares an absolute dependency. A package will
4352 not be configured unless all of the packages listed in
4353 its
<tt>Depends
</tt> field have been correctly
4358 The
<tt>Depends
</tt> field should be used if the
4359 depended-on package is required for the depending
4360 package to provide a significant amount of
4365 The
<tt>Depends
</tt> field should also be used if the
4366 <prgn>postinst
</prgn>,
<prgn>prerm
</prgn> or
4367 <prgn>postrm
</prgn> scripts require the package to be
4368 present in order to run. Note, however, that the
4369 <prgn>postrm
</prgn> cannot rely on any non-essential
4370 packages to be present during the
<tt>purge
</tt>
4374 <tag><tt>Recommends
</tt></tag>
4377 This declares a strong, but not absolute, dependency.
4381 The
<tt>Recommends
</tt> field should list packages
4382 that would be found together with this one in all but
4383 unusual installations.
4387 <tag><tt>Suggests
</tt></tag>
4389 This is used to declare that one package may be more
4390 useful with one or more others. Using this field
4391 tells the packaging system and the user that the
4392 listed packages are related to this one and can
4393 perhaps enhance its usefulness, but that installing
4394 this one without them is perfectly reasonable.
4397 <tag><tt>Enhances
</tt></tag>
4399 This field is similar to Suggests but works in the
4400 opposite direction. It is used to declare that a
4401 package can enhance the functionality of another
4405 <tag><tt>Pre-Depends
</tt></tag>
4408 This field is like
<tt>Depends
</tt>, except that it
4409 also forces
<prgn>dpkg
</prgn> to complete installation
4410 of the packages named before even starting the
4411 installation of the package which declares the
4412 pre-dependency, as follows:
4416 When a package declaring a pre-dependency is about to
4417 be
<em>unpacked
</em> the pre-dependency can be
4418 satisfied if the depended-on package is either fully
4419 configured,
<em>or even if
</em> the depended-on
4420 package(s) are only unpacked or half-configured,
4421 provided that they have been configured correctly at
4422 some point in the past (and not removed or partially
4423 removed since). In this case, both the
4424 previously-configured and currently unpacked or
4425 half-configured versions must satisfy any version
4426 clause in the
<tt>Pre-Depends
</tt> field.
4430 When the package declaring a pre-dependency is about
4431 to be
<em>configured
</em>, the pre-dependency will be
4432 treated as a normal
<tt>Depends
</tt>, that is, it will
4433 be considered satisfied only if the depended-on
4434 package has been correctly configured.
4438 <tt>Pre-Depends
</tt> should be used sparingly,
4439 preferably only by packages whose premature upgrade or
4440 installation would hamper the ability of the system to
4441 continue with any upgrade that might be in progress.
4445 <tt>Pre-Depends
</tt> are also required if the
4446 <prgn>preinst
</prgn> script depends on the named
4447 package. It is best to avoid this situation if
4455 When selecting which level of dependency to use you should
4456 consider how important the depended-on package is to the
4457 functionality of the one declaring the dependency. Some
4458 packages are composed of components of varying degrees of
4459 importance. Such a package should list using
4460 <tt>Depends
</tt> the package(s) which are required by the
4461 more important components. The other components'
4462 requirements may be mentioned as Suggestions or
4463 Recommendations, as appropriate to the components' relative
4469 <heading>Packages which break other packages -
<tt>Breaks
</tt></heading>
4472 When one binary package declares that it breaks another,
4473 <prgn>dpkg
</prgn> will refuse to allow the package which
4474 declares
<tt>Breaks
</tt> be installed unless the broken
4475 package is deconfigured first, and it will refuse to
4476 allow the broken package to be reconfigured.
4480 A package will not be regarded as causing breakage merely
4481 because its configuration files are still installed; it must
4482 be at least half-installed.
4486 A special exception is made for packages which declare that
4487 they break their own package name or a virtual package which
4488 they provide (see below): this does not count as a real
4493 Normally a
<tt>Breaks
</tt> entry will have an
"earlier than"
4494 version clause; such a
<tt>Breaks
</tt> is introduced in the
4495 version of an (implicit or explicit) dependency which
4496 violates an assumption or reveals a bug in earlier versions
4497 of the broken package. This use of
<tt>Breaks
</tt> will
4498 inform higher-level package management tools that broken
4499 package must be upgraded before the new one.
4503 If the breaking package also overwrites some files from the
4504 older package, it should use
<tt>Replaces
</tt> (not
4505 <tt>Conflicts
</tt>) to ensure this goes smoothly.
4509 <sect id=
"conflicts">
4510 <heading>Conflicting binary packages -
<tt>Conflicts
</tt></heading>
4513 When one binary package declares a conflict with another
4514 using a
<tt>Conflicts
</tt> field,
<prgn>dpkg
</prgn> will
4515 refuse to allow them to be installed on the system at the
4520 If one package is to be installed, the other must be removed
4521 first - if the package being installed is marked as
4522 replacing (see
<ref id=
"replaces">) the one on the system,
4523 or the one on the system is marked as deselected, or both
4524 packages are marked
<tt>Essential
</tt>, then
4525 <prgn>dpkg
</prgn> will automatically remove the package
4526 which is causing the conflict, otherwise it will halt the
4527 installation of the new package with an error. This
4528 mechanism is specifically designed to produce an error when
4529 the installed package is
<tt>Essential
</tt>, but the new
4534 A package will not cause a conflict merely because its
4535 configuration files are still installed; it must be at least
4540 A special exception is made for packages which declare a
4541 conflict with their own package name, or with a virtual
4542 package which they provide (see below): this does not
4543 prevent their installation, and allows a package to conflict
4544 with others providing a replacement for it. You use this
4545 feature when you want the package in question to be the only
4546 package providing some feature.
4550 A
<tt>Conflicts
</tt> entry should almost never have an
4551 "earlier than" version clause. This would prevent
4552 <prgn>dpkg
</prgn> from upgrading or installing the package
4553 which declared such a conflict until the upgrade or removal
4554 of the conflicted-with package had been completed. Instead,
4555 <tt>Breaks
</tt> may be used.
4559 <sect id=
"virtual"><heading>Virtual packages -
<tt>Provides
</tt>
4563 As well as the names of actual (
"concrete") packages, the
4564 package relationship fields
<tt>Depends
</tt>,
4565 <tt>Recommends
</tt>,
<tt>Suggests
</tt>,
<tt>Enhances
</tt>,
4566 <tt>Pre-Depends
</tt>,
<tt>Breaks
</tt>,
<tt>Conflicts
</tt>,
4567 <tt>Build-Depends
</tt>,
<tt>Build-Depends-Indep
</tt>,
4568 <tt>Build-Conflicts
</tt> and
<tt>Build-Conflicts-Indep
</tt>
4569 may mention
"virtual packages".
4573 A
<em>virtual package
</em> is one which appears in the
4574 <tt>Provides
</tt> control file field of another package.
4575 The effect is as if the package(s) which provide a
4576 particular virtual package name had been listed by name
4577 everywhere the virtual package name appears. (See also
<ref
4582 If there are both concrete and virtual packages of the same
4583 name, then the dependency may be satisfied (or the conflict
4584 caused) by either the concrete package with the name in
4585 question or any other concrete package which provides the
4586 virtual package with the name in question. This is so that,
4587 for example, supposing we have
4588 <example compact=
"compact">
4591 </example> and someone else releases an enhanced version of
4592 the
<tt>bar
</tt> package they can say:
4593 <example compact=
"compact">
4597 and the
<tt>bar-plus
</tt> package will now also satisfy the
4598 dependency for the
<tt>foo
</tt> package.
4602 If a relationship field has a version number attached
4603 then only real packages will be considered to see whether
4604 the relationship is satisfied (or the prohibition violated,
4605 for a conflict or breakage) - it is assumed that a real
4606 package which provides the virtual package is not of the
4607 "right" version. So, a
<tt>Provides
</tt> field may not
4608 contain version numbers, and the version number of the
4609 concrete package which provides a particular virtual package
4610 will not be looked at when considering a dependency on or
4611 conflict with the virtual package name.
4615 It is likely that the ability will be added in a future
4616 release of
<prgn>dpkg
</prgn> to specify a version number for
4617 each virtual package it provides. This feature is not yet
4618 present, however, and is expected to be used only
4623 If you want to specify which of a set of real packages
4624 should be the default to satisfy a particular dependency on
4625 a virtual package, you should list the real package as an
4626 alternative before the virtual one.
4631 <sect id=
"replaces"><heading>Overwriting files and replacing
4632 packages -
<tt>Replaces
</tt></heading>
4635 Packages can declare in their control file that they should
4636 overwrite files in certain other packages, or completely
4637 replace other packages. The
<tt>Replaces
</tt> control file
4638 field has these two distinct purposes.
4641 <sect1><heading>Overwriting files in other packages
</heading>
4644 Firstly, as mentioned before, it is usually an error for a
4645 package to contain files which are on the system in
4650 However, if the overwriting package declares that it
4651 <tt>Replaces
</tt> the one containing the file being
4652 overwritten, then
<prgn>dpkg
</prgn> will replace the file
4653 from the old package with that from the new. The file
4654 will no longer be listed as
"owned" by the old package.
4658 If a package is completely replaced in this way, so that
4659 <prgn>dpkg
</prgn> does not know of any files it still
4660 contains, it is considered to have
"disappeared". It will
4661 be marked as not wanted on the system (selected for
4662 removal) and not installed. Any
<tt>conffile
</tt>s
4663 details noted for the package will be ignored, as they
4664 will have been taken over by the overwriting package. The
4665 package's
<prgn>postrm
</prgn> script will be run with a
4666 special argument to allow the package to do any final
4667 cleanup required. See
<ref id=
"mscriptsinstact">.
4670 Replaces is a one way relationship -- you have to
4671 install the replacing package after the replaced
4678 For this usage of
<tt>Replaces
</tt>, virtual packages (see
4679 <ref id=
"virtual">) are not considered when looking at a
4680 <tt>Replaces
</tt> field - the packages declared as being
4681 replaced must be mentioned by their real names.
4685 Furthermore, this usage of
<tt>Replaces
</tt> only takes
4686 effect when both packages are at least partially on the
4687 system at once, so that it can only happen if they do not
4688 conflict or if the conflict has been overridden.
4693 <sect1><heading>Replacing whole packages, forcing their
4697 Secondly,
<tt>Replaces
</tt> allows the packaging system to
4698 resolve which package should be removed when there is a
4699 conflict - see
<ref id=
"conflicts">. This usage only
4700 takes effect when the two packages
<em>do
</em> conflict,
4701 so that the two usages of this field do not interfere with
4706 In this situation, the package declared as being replaced
4707 can be a virtual package, so for example, all mail
4708 transport agents (MTAs) would have the following fields in
4709 their control files:
4710 <example compact=
"compact">
4711 Provides: mail-transport-agent
4712 Conflicts: mail-transport-agent
4713 Replaces: mail-transport-agent
4715 ensuring that only one MTA can be installed at any one
4720 <sect id=
"sourcebinarydeps">
4721 <heading>Relationships between source and binary packages -
4722 <tt>Build-Depends
</tt>,
<tt>Build-Depends-Indep
</tt>,
4723 <tt>Build-Conflicts
</tt>,
<tt>Build-Conflicts-Indep
</tt>
4727 Source packages that require certain binary packages to be
4728 installed or absent at the time of building the package
4729 can declare relationships to those binary packages.
4733 This is done using the
<tt>Build-Depends
</tt>,
4734 <tt>Build-Depends-Indep
</tt>,
<tt>Build-Conflicts
</tt> and
4735 <tt>Build-Conflicts-Indep
</tt> control file fields.
4739 Build-dependencies on
"build-essential" binary packages can be
4740 omitted. Please see
<ref id=
"pkg-relations"> for more information.
4744 The dependencies and conflicts they define must be satisfied
4745 (as defined earlier for binary packages) in order to invoke
4746 the targets in
<tt>debian/rules
</tt>, as follows:
<footnote>
4748 If you make
"build-arch" or
"binary-arch", you need
4749 Build-Depends. If you make
"build-indep" or
4750 "binary-indep", you need Build-Depends and
4751 Build-Depends-Indep. If you make
"build" or
"binary",
4755 There is no Build-Depends-Arch; this role is essentially
4756 met with Build-Depends. Anyone building the
4757 <tt>build-indep
</tt> and binary-indep
<tt></tt> targets
4758 is basically assumed to be building the whole package
4759 anyway and so installs all build dependencies. The
4760 autobuilders use
<tt>dpkg-buildpackage -B
</tt>, which
4761 calls
<tt>build
</tt> (not
<tt>build-arch
</tt>, since it
4762 does not yet know how to check for its existence) and
4763 <tt>binary-arch
</tt>.
4766 The purpose of the original split, I recall, was so that
4767 the autobuilders wouldn't need to install extra packages
4768 needed only for the binary-indep targets. But without a
4769 build-arch/build-indep split, this didn't work, since
4770 most of the work is done in the build target, not in the
4776 <tag><tt>Build-Depends
</tt>,
<tt>Build-Conflicts
</tt></tag>
4778 The
<tt>Build-Depends
</tt> and
4779 <tt>Build-Conflicts
</tt> fields must be satisfied when
4780 any of the following targets is invoked:
4781 <tt>build
</tt>,
<tt>clean
</tt>,
<tt>binary
</tt>,
4782 <tt>binary-arch
</tt>,
<tt>build-arch
</tt>,
4783 <tt>build-indep
</tt> and
<tt>binary-indep
</tt>.
4785 <tag><tt>Build-Depends-Indep
</tt>,
4786 <tt>Build-Conflicts-Indep
</tt></tag>
4788 The
<tt>Build-Depends-Indep
</tt> and
4789 <tt>Build-Conflicts-Indep
</tt> fields must be
4790 satisfied when any of the following targets is
4791 invoked:
<tt>build
</tt>,
<tt>build-indep
</tt>,
4792 <tt>binary
</tt> and
<tt>binary-indep
</tt>.
4802 <chapt id=
"sharedlibs"><heading>Shared libraries
</heading>
4805 Packages containing shared libraries must be constructed with
4806 a little care to make sure that the shared library is always
4807 available. This is especially important for packages whose
4808 shared libraries are vitally important, such as the C library
4809 (currently
<tt>libc6
</tt>).
4813 Packages involving shared libraries should be split up into
4814 several binary packages. This section mostly deals with how
4815 this separation is to be accomplished; rules for files within
4816 the shared library packages are in
<ref id=
"libraries"> instead.
4819 <sect id=
"sharedlibs-runtime">
4820 <heading>Run-time shared libraries
</heading>
4823 The run-time shared library needs to be placed in a package
4824 whose name changes whenever the shared object version
4827 Since it is common place to install several versions of a
4828 package that just provides shared libraries, it is a
4829 good idea that the library package should not
4830 contain any extraneous non-versioned files, unless they
4831 happen to be in versioned directories.
</p>
4833 The most common mechanism is to place it in a package
4835 <package><var>libraryname
</var><var>soversion
</var></package>,
4836 where
<file><var>soversion
</var></file> is the version number
4837 in the soname of the shared library
<footnote>
4838 The soname is the shared object name: it's the thing
4839 that has to match exactly between building an executable
4840 and running it for the dynamic linker to be able run the
4841 program. For example, if the soname of the library is
4842 <file>libfoo.so
.6</file>, the library package would be
4843 called
<file>libfoo6
</file>.
4845 Alternatively, if it would be confusing to directly append
4846 <var>soversion
</var> to
<var>libraryname
</var> (e.g. because
4847 <var>libraryname
</var> itself ends in a number), you may use
4848 <package><var>libraryname
</var>-
<var>soversion
</var></package> and
4849 <package><var>libraryname
</var>-
<var>soversion
</var>-dev
</package>
4854 If you have several shared libraries built from the same
4855 source tree you may lump them all together into a single
4856 shared library package, provided that you change all of
4857 their sonames at once (so that you don't get filename
4858 clashes if you try to install different versions of the
4859 combined shared libraries package).
4863 The package should install the shared libraries under
4864 their normal names. For example, the
<package>libgdbm3
</package>
4865 package should install
<file>libgdbm.so
.3.0.0</file> as
4866 <file>/usr/lib/libgdbm.so
.3.0.0</file>. The files should not be
4867 renamed or re-linked by any
<prgn>prerm
</prgn> or
4868 <prgn>postrm
</prgn> scripts;
<prgn>dpkg
</prgn> will take care
4869 of renaming things safely without affecting running programs,
4870 and attempts to interfere with this are likely to lead to
4875 Shared libraries should not be installed executable, since
4876 the dynamic linker does not require this and trying to
4877 execute a shared library usually results in a core dump.
4881 The run-time library package should include the symbolic link that
4882 <prgn>ldconfig
</prgn> would create for the shared libraries.
4883 For example, the
<package>libgdbm3
</package> package should include
4884 a symbolic link from
<file>/usr/lib/libgdbm.so
.3</file> to
4885 <file>libgdbm.so
.3.0.0</file>. This is needed so that the dynamic
4886 linker (for example
<prgn>ld.so
</prgn> or
4887 <prgn>ld-linux.so.*
</prgn>) can find the library between the
4888 time that
<prgn>dpkg
</prgn> installs it and the time that
4889 <prgn>ldconfig
</prgn> is run in the
<prgn>postinst
</prgn>
4891 The package management system requires the library to be
4892 placed before the symbolic link pointing to it in the
4893 <file>.deb
</file> file. This is so that when
4894 <prgn>dpkg
</prgn> comes to install the symlink
4895 (overwriting the previous symlink pointing at an older
4896 version of the library), the new shared library is already
4897 in place. In the past, this was achieved by creating the
4898 library in the temporary packaging directory before
4899 creating the symlink. Unfortunately, this was not always
4900 effective, since the building of the tar file in the
4901 <file>.deb
</file> depended on the behavior of the underlying
4902 file system. Some file systems (such as reiserfs) reorder
4903 the files so that the order of creation is forgotten.
4904 Since version
1.7.0,
<prgn>dpkg
</prgn>
4905 reorders the files itself as necessary when building a
4906 package. Thus it is no longer important to concern
4907 oneself with the order of file creation.
4911 <sect1 id=
"ldconfig">
4912 <heading><tt>ldconfig
</tt></heading>
4915 Any package installing shared libraries in one of the default
4916 library directories of the dynamic linker (which are currently
4917 <file>/usr/lib
</file> and
<file>/lib
</file>) or a directory that is
4918 listed in
<file>/etc/ld.so.conf
</file><footnote>
4920 <list compact=
"compact">
4921 <item>/usr/local/lib
</item>
4922 <item>/usr/lib/libc5-compat
</item>
4923 <item>/lib/libc5-compat
</item>
4926 must use
<prgn>ldconfig
</prgn> to update the shared library
4931 The package maintainer scripts must only call
4932 <prgn>ldconfig
</prgn> under these circumstances:
4933 <list compact=
"compact">
4934 <item>When the
<prgn>postinst
</prgn> script is run with a
4935 first argument of
<tt>configure
</tt>, the script must call
4936 <prgn>ldconfig
</prgn>, and may optionally invoke
4937 <prgn>ldconfig
</prgn> at other times.
4939 <item>When the
<prgn>postrm
</prgn> script is run with a
4940 first argument of
<tt>remove
</tt>, the script should call
4941 <prgn>ldconfig
</prgn>.
4946 During install or upgrade, the preinst is called before
4947 the new files are installed, so calling
"ldconfig" is
4948 pointless. The preinst of an existing package can also be
4949 called if an upgrade fails. However, this happens during
4950 the critical time when a shared libs may exist on-disk
4951 under a temporary name. Thus, it is dangerous and
4952 forbidden by current policy to call
"ldconfig" at this
4957 When a package is installed or upgraded,
"postinst
4958 configure" runs after the new files are safely on-disk.
4959 Since it is perfectly safe to invoke ldconfig
4960 unconditionally in a postinst, it is OK for a package to
4961 simply put ldconfig in its postinst without checking the
4962 argument. The postinst can also be called to recover from
4963 a failed upgrade. This happens before any new files are
4964 unpacked, so there is no reason to call
"ldconfig" at this
4969 For a package that is being removed, prerm is
4970 called with all the files intact, so calling ldconfig is
4971 useless. The other calls to
"prerm" happen in the case of
4972 upgrade at a time when all the files of the old package
4973 are on-disk, so again calling
"ldconfig" is pointless.
4977 postrm, on the other hand, is called with the
"remove"
4978 argument just after the files are removed, so this is
4979 the proper time to call
"ldconfig" to notify the system
4980 of the fact that the shared libraries from the package
4981 are removed. The postrm can be called at several other
4982 times. At the time of
"postrm purge",
"postrm
4983 abort-install", or
"postrm abort-upgrade", calling
4984 "ldconfig" is useless because the shared lib files are
4985 not on-disk. However, when
"postrm" is invoked with
4986 arguments
"upgrade",
"failed-upgrade", or
"disappear", a
4987 shared lib may exist on-disk under a temporary filename.
4995 <sect id=
"sharedlibs-support-files">
4996 <heading>Shared library support files
</heading>
4999 If your package contains files whose names do not change with
5000 each change in the library shared object version, you must not
5001 put them in the shared library package. Otherwise, several
5002 versions of the shared library cannot be installed at the same
5003 time without filename clashes, making upgrades and transitions
5004 unnecessarily difficult.
5008 It is recommended that supporting files and run-time support
5009 programs that do not need to be invoked manually by users, but
5010 are nevertheless required for the package to function, be placed
5011 (if they are binary) in a subdirectory of
<file>/usr/lib
</file>,
5012 preferably under
<file>/usr/lib/
</file><var>package-name
</var>.
5013 If the program or file is architecture independent, the
5014 recommendation is for it to be placed in a subdirectory of
5015 <file>/usr/share
</file> instead, preferably under
5016 <file>/usr/share/
</file><var>package-name
</var>. Following the
5017 <var>package-name
</var> naming convention ensures that the file
5018 names change when the shared object version changes.
5022 Run-time support programs that use the shared library but are
5023 not required for the library to function or files used by the
5024 shared library that can be used by any version of the shared
5025 library package should instead be put in a separate package.
5026 This package might typically be named
5027 <package><var>libraryname
</var>-tools
</package>; note the
5028 absence of the
<var>soversion
</var> in the package name.
5032 Files and support programs only useful when compiling software
5033 against the library should be included in the development
5034 package for the library.
<footnote>
5035 For example, a
<file><var>package-name
</var>-config
</file>
5036 script or
<package>pkg-config
</package> configuration files.
5041 <sect id=
"sharedlibs-static">
5042 <heading>Static libraries
</heading>
5045 The static library (
<file><var>libraryname.a
</var></file>)
5046 is usually provided in addition to the shared version.
5047 It is placed into the development package (see below).
5051 In some cases, it is acceptable for a library to be
5052 available in static form only; these cases include:
5054 <item>libraries for languages whose shared library support
5055 is immature or unstable
</item>
5056 <item>libraries whose interfaces are in flux or under
5057 development (commonly the case when the library's
5058 major version number is zero, or where the ABI breaks
5059 across patchlevels)
</item>
5060 <item>libraries which are explicitly intended to be
5061 available only in static form by their upstream
5066 <sect id=
"sharedlibs-dev">
5067 <heading>Development files
</heading>
5070 The development files associated to a shared library need to be
5071 placed in a package called
5072 <package><var>libraryname
</var><var>soversion
</var>-dev
</package>,
5073 or if you prefer only to support one development version at a
5074 time,
<package><var>libraryname
</var>-dev
</package>.
5078 In case several development versions of a library exist, you may
5079 need to use
<prgn>dpkg
</prgn>'s Conflicts mechanism (see
5080 <ref id=
"conflicts">) to ensure that the user only installs one
5081 development version at a time (as different development versions are
5082 likely to have the same header files in them, which would cause a
5083 filename clash if both were installed).
5087 The development package should contain a symlink for the associated
5088 shared library without a version number. For example, the
5089 <package>libgdbm-dev
</package> package should include a symlink
5090 from
<file>/usr/lib/libgdbm.so
</file> to
5091 <file>libgdbm.so
.3.0.0</file>. This symlink is needed by the linker
5092 (
<prgn>ld
</prgn>) when compiling packages, as it will only look for
5093 <file>libgdbm.so
</file> when compiling dynamically.
5097 <sect id=
"sharedlibs-intradeps">
5098 <heading>Dependencies between the packages of the same library
</heading>
5101 Typically the development version should have an exact
5102 version dependency on the runtime library, to make sure that
5103 compilation and linking happens correctly. The
5104 <tt>${binary:Version}
</tt> substitution variable can be
5105 useful for this purpose.
5107 Previously,
<tt>${Source-Version}
</tt> was used, but its name
5108 was confusing and it has been deprecated since dpkg
1.13.19.
5113 <sect id=
"sharedlibs-shlibdeps">
5114 <heading>Dependencies between the library and other packages -
5115 the
<tt>shlibs
</tt> system
</heading>
5118 If a package contains a binary or library which links to a
5119 shared library, we must ensure that when the package is
5120 installed on the system, all of the libraries needed are
5121 also installed. This requirement led to the creation of the
5122 <tt>shlibs
</tt> system, which is very simple in its design:
5123 any package which
<em>provides
</em> a shared library also
5124 provides information on the package dependencies required to
5125 ensure the presence of this library, and any package which
5126 <em>uses
</em> a shared library uses this information to
5127 determine the dependencies it requires. The files which
5128 contain the mapping from shared libraries to the necessary
5129 dependency information are called
<file>shlibs
</file> files.
5133 Thus, when a package is built which contains any shared
5134 libraries, it must provide a
<file>shlibs
</file> file for other
5135 packages to use, and when a package is built which contains
5136 any shared libraries or compiled binaries, it must run
5137 <qref id=
"pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps
</prgn></qref>
5138 on these to determine the libraries used and hence the
5139 dependencies needed by this package.
<footnote>
5141 In the past, the shared libraries linked to were
5142 determined by calling
<prgn>ldd
</prgn>, but now
5143 <prgn>objdump
</prgn> is used to do this. The only
5144 change this makes to package building is that
5145 <prgn>dpkg-shlibdeps
</prgn> must also be run on shared
5146 libraries, whereas in the past this was unnecessary.
5147 The rest of this footnote explains the advantage that
5152 We say that a binary
<tt>foo
</tt> <em>directly
</em> uses
5153 a library
<tt>libbar
</tt> if it is explicitly linked
5154 with that library (that is, it uses the flag
5155 <tt>-lbar
</tt> during the linking stage). Other
5156 libraries that are needed by
<tt>libbar
</tt> are linked
5157 <em>indirectly
</em> to
<tt>foo
</tt>, and the dynamic
5158 linker will load them automatically when it loads
5159 <tt>libbar
</tt>. A package should depend on
5160 the libraries it directly uses, and the dependencies for
5161 those libraries should automatically pull in the other
5166 Unfortunately, the
<prgn>ldd
</prgn> program shows both
5167 the directly and indirectly used libraries, meaning that
5168 the dependencies determined included both direct and
5169 indirect dependencies. The use of
<prgn>objdump
</prgn>
5170 avoids this problem by determining only the directly
5175 A good example of where this helps is the following. We
5176 could update
<tt>libimlib
</tt> with a new version that
5177 supports a new graphics format called dgf (but retaining
5178 the same major version number). If we used the old
5179 <prgn>ldd
</prgn> method, every package that uses
5180 <tt>libimlib
</tt> would need to be recompiled so it
5181 would also depend on
<tt>libdgf
</tt> or it wouldn't run
5182 due to missing symbols. However with the new system,
5183 packages using
<tt>libimlib
</tt> can rely on
5184 <tt>libimlib
</tt> itself having the dependency on
5185 <tt>libdgf
</tt> and so they would not need rebuilding.
5191 In the following sections, we will first describe where the
5192 various
<tt>shlibs
</tt> files are to be found, then how to
5193 use
<prgn>dpkg-shlibdeps
</prgn>, and finally the
<tt>shlibs
</tt>
5194 file format and how to create them if your package contains a
5199 <heading>The
<tt>shlibs
</tt> files present on the system
</heading>
5202 There are several places where
<tt>shlibs
</tt> files are
5203 found. The following list gives them in the order in which
5205 <qref id=
"pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps
</prgn></qref>.
5206 (The first one which gives the required information is used.)
5212 <p><file>debian/shlibs.local
</file></p>
5215 This lists overrides for this package. Its use is
5216 described below (see
<ref id=
"shlibslocal">).
5221 <p><file>/etc/dpkg/shlibs.override
</file></p>
5224 This lists global overrides. This list is normally
5225 empty. It is maintained by the local system
5231 <p><file>DEBIAN/shlibs
</file> files in the
"build directory"</p>
5234 When packages are being built, any
5235 <file>debian/shlibs
</file> files are copied into the
5236 control file area of the temporary build directory and
5237 given the name
<file>shlibs
</file>. These files give
5238 details of any shared libraries included in the
5240 An example may help here. Let us say that the
5241 source package
<tt>foo
</tt> generates two binary
5242 packages,
<tt>libfoo2
</tt> and
5243 <tt>foo-runtime
</tt>. When building the binary
5244 packages, the two packages are created in the
5245 directories
<file>debian/libfoo2
</file> and
5246 <file>debian/foo-runtime
</file> respectively.
5247 (
<file>debian/tmp
</file> could be used instead of one
5248 of these.) Since
<tt>libfoo2
</tt> provides the
5249 <tt>libfoo
</tt> shared library, it will require a
5250 <tt>shlibs
</tt> file, which will be installed in
5251 <file>debian/libfoo2/DEBIAN/shlibs
</file>, eventually
5253 <file>/var/lib/dpkg/info/libfoo2.shlibs
</file>. Then
5254 when
<prgn>dpkg-shlibdeps
</prgn> is run on the
5256 <file>debian/foo-runtime/usr/bin/foo-prog
</file>, it
5258 <file>debian/libfoo2/DEBIAN/shlibs
</file> file to
5259 determine whether
<tt>foo-prog
</tt>'s library
5260 dependencies are satisfied by any of the libraries
5261 provided by
<tt>libfoo2
</tt>. For this reason,
5262 <prgn>dpkg-shlibdeps
</prgn> must only be run once
5263 all of the individual binary packages'
5264 <tt>shlibs
</tt> files have been installed into the
5271 <p><file>/var/lib/dpkg/info/*.shlibs
</file></p>
5274 These are the
<file>shlibs
</file> files corresponding to
5275 all of the packages installed on the system, and are
5276 maintained by the relevant package maintainers.
5281 <p><file>/etc/dpkg/shlibs.default
</file></p>
5284 This file lists any shared libraries whose packages
5285 have failed to provide correct
<file>shlibs
</file> files.
5286 It was used when the
<file>shlibs
</file> setup was first
5287 introduced, but it is now normally empty. It is
5288 maintained by the
<tt>dpkg
</tt> maintainer.
5296 <heading>How to use
<prgn>dpkg-shlibdeps
</prgn> and the
5297 <file>shlibs
</file> files
</heading>
5301 <qref id=
"pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps
</prgn></qref>
5302 into your
<file>debian/rules
</file> file. If your package
5303 contains only compiled binaries and libraries (but no scripts),
5304 you can use a command such as:
5305 <example compact=
"compact">
5306 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5307 debian/tmp/usr/lib/*
5309 Otherwise, you will need to explicitly list the compiled
5310 binaries and libraries.
<footnote>
5311 If you are using
<tt>debhelper
</tt>, the
5312 <prgn>dh_shlibdeps
</prgn> program will do this work for
5313 you. It will also correctly handle multi-binary
5319 This command puts the dependency information into the
5320 <file>debian/substvars
</file> file, which is then used by
5321 <prgn>dpkg-gencontrol
</prgn>. You will need to place a
5322 <tt>${shlibs:Depends}
</tt> variable in the
<tt>Depends
</tt>
5323 field in the control file for this to work.
5327 If
<prgn>dpkg-shlibdeps
</prgn> doesn't complain, you're
5328 done. If it does complain you might need to create your own
5329 <file>debian/shlibs.local
</file> file, as explained below (see
5330 <ref id=
"shlibslocal">).
5334 If you have multiple binary packages, you will need to call
5335 <prgn>dpkg-shlibdeps
</prgn> on each one which contains
5336 compiled libraries or binaries. In such a case, you will
5337 need to use the
<tt>-T
</tt> option to the
<tt>dpkg
</tt>
5338 utilities to specify a different
<file>substvars
</file> file.
5342 If you are creating a udeb for use in the Debian Installer, you
5343 will need to specify that
<prgn>dpkg-shlibdeps
</prgn> should use
5344 the dependency line of type
<tt>udeb
</tt> by adding
5345 <tt>-tudeb
</tt> as option
<footnote>
5346 <prgn>dh_shlibdeps
</prgn> from the
<tt>debhelper
</tt> suite
5347 will automatically add this option if it knows it is
5349 </footnote>. If there is no dependency line of type
<tt>udeb
</tt>
5350 in the
<file>shlibs
</file> file,
<prgn>dpkg-shlibdeps
</prgn> will
5351 fall back to the regular dependency line.
5355 For more details on dpkg-shlibdeps, please see
5356 <ref id=
"pkg-dpkg-shlibdeps"> and
5357 <manref name=
"dpkg-shlibdeps" section=
"1">.
5362 <heading>The
<file>shlibs
</file> File Format
</heading>
5365 Each
<file>shlibs
</file> file has the same format. Lines
5366 beginning with
<tt>#
</tt> are considered to be comments and
5367 are ignored. Each line is of the form:
5368 <example compact=
"compact">
5369 [
<var>type
</var>: ]
<var>library-name
</var> <var>soname-version
</var> <var>dependencies ...
</var>
5374 We will explain this by reference to the example of the
5375 <tt>zlib1g
</tt> package, which (at the time of writing)
5376 installs the shared library
<file>/usr/lib/libz.so
.1.1.3</file>.
5380 <var>type
</var> is an optional element that indicates the type
5381 of package for which the line is valid. The only type currently
5382 in use is
<tt>udeb
</tt>. The colon and space after the type are
5387 <var>library-name
</var> is the name of the shared library,
5388 in this case
<tt>libz
</tt>. (This must match the name part
5389 of the soname, see below.)
5393 <var>soname-version
</var> is the version part of the soname of
5394 the library. The soname is the thing that must exactly match
5395 for the library to be recognized by the dynamic linker, and is
5397 <tt><var>name
</var>.so.
<var>major-version
</var></tt>, in our
5398 example,
<tt>libz.so
.1</tt>.
<footnote>
5399 This can be determined using the command
5400 <example compact=
"compact">
5401 objdump -p /usr/lib/libz.so
.1.1.3 | grep SONAME
5404 The version part is the part which comes after
5405 <tt>.so.
</tt>, so in our case, it is
<tt>1</tt>.
5409 <var>dependencies
</var> has the same syntax as a dependency
5410 field in a binary package control file. It should give
5411 details of which packages are required to satisfy a binary
5412 built against the version of the library contained in the
5413 package. See
<ref id=
"depsyntax"> for details.
5417 In our example, if the first version of the
<tt>zlib1g
</tt>
5418 package which contained a minor number of at least
5419 <tt>1.3</tt> was
<var>1:
1.1.3-
1</var>, then the
5420 <tt>shlibs
</tt> entry for this library could say:
5421 <example compact=
"compact">
5422 libz
1 zlib1g (
>=
1:
1.1.3)
5424 The version-specific dependency is to avoid warnings from
5425 the dynamic linker about using older shared libraries with
5430 As zlib1g also provides a udeb containing the shared library,
5431 there would also be a second line:
5432 <example compact=
"compact">
5433 udeb: libz
1 zlib1g-udeb (
>=
1:
1.1.3)
5439 <heading>Providing a
<file>shlibs
</file> file
</heading>
5442 If your package provides a shared library, you need to create
5443 a
<file>shlibs
</file> file following the format described above.
5444 It is usual to call this file
<file>debian/shlibs
</file> (but if
5445 you have multiple binary packages, you might want to call it
5446 <file>debian/shlibs.
<var>package
</var></file> instead). Then
5447 let
<file>debian/rules
</file> install it in the control area:
5448 <example compact=
"compact">
5449 install -m644 debian/shlibs debian/tmp/DEBIAN
5451 or, in the case of a multi-binary package:
5452 <example compact=
"compact">
5453 install -m644 debian/shlibs.
<var>package
</var> debian/
<var>package
</var>/DEBIAN/shlibs
5455 An alternative way of doing this is to create the
5456 <file>shlibs
</file> file in the control area directly from
5457 <file>debian/rules
</file> without using a
<file>debian/shlibs
</file>
5458 file at all,
<footnote>
5459 This is what
<prgn>dh_makeshlibs
</prgn> in the
5460 <tt>debhelper
</tt> suite does. If your package also has a udeb
5461 that provides a shared library,
<prgn>dh_makeshlibs
</prgn> can
5462 automatically generate the
<tt>udeb:
</tt> lines if you specify
5463 the name of the udeb with the
<tt>--add-udeb
</tt> option.
5465 since the
<file>debian/shlibs
</file> file itself is ignored by
5466 <prgn>dpkg-shlibdeps
</prgn>.
5470 As
<prgn>dpkg-shlibdeps
</prgn> reads the
5471 <file>DEBIAN/shlibs
</file> files in all of the binary packages
5472 being built from this source package, all of the
5473 <file>DEBIAN/shlibs
</file> files should be installed before
5474 <prgn>dpkg-shlibdeps
</prgn> is called on any of the binary
5479 <sect1 id=
"shlibslocal">
5480 <heading>Writing the
<file>debian/shlibs.local
</file> file
</heading>
5483 This file is intended only as a
<em>temporary
</em> fix if
5484 your binaries or libraries depend on a library whose package
5485 does not yet provide a correct
<file>shlibs
</file> file.
5489 We will assume that you are trying to package a binary
5490 <tt>foo
</tt>. When you try running
5491 <prgn>dpkg-shlibdeps
</prgn> you get the following error
5492 message (
<tt>-O
</tt> displays the dependency information on
5493 <tt>stdout
</tt> instead of writing it to
5494 <tt>debian/substvars
</tt>, and the lines have been wrapped
5495 for ease of reading):
5496 <example compact=
"compact">
5497 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5498 dpkg-shlibdeps: warning: unable to find dependency
5499 information for shared library libbar (soname
1,
5500 path /usr/lib/libbar.so
.1, dependency field Depends)
5501 shlibs:Depends=libc6 (
>=
2.2.2-
2)
5503 You can then run
<prgn>ldd
</prgn> on the binary to find the
5504 full location of the library concerned:
5505 <example compact=
"compact">
5507 libbar.so
.1 =
> /usr/lib/libbar.so
.1 (
0x4001e000)
5508 libc.so
.6 =
> /lib/libc.so
.6 (
0x40032000)
5509 /lib/ld-linux.so
.2 =
> /lib/ld-linux.so
.2 (
0x40000000)
5511 So the
<prgn>foo
</prgn> binary depends on the
5512 <prgn>libbar
</prgn> shared library, but no package seems to
5513 provide a
<file>*.shlibs
</file> file handling
5514 <file>libbar.so
.1</file> in
<file>/var/lib/dpkg/info/
</file>. Let's
5515 determine the package responsible:
5516 <example compact=
"compact">
5517 $ dpkg -S /usr/lib/libbar.so
.1
5518 bar1: /usr/lib/libbar.so
.1
5519 $ dpkg -s bar1 | grep Version
5522 This tells us that the
<tt>bar1
</tt> package, version
1.0-
1,
5523 is the one we are using. Now we can file a bug against the
5524 <tt>bar1
</tt> package and create our own
5525 <file>debian/shlibs.local
</file> to locally fix the problem.
5526 Including the following line into your
5527 <file>debian/shlibs.local
</file> file:
5528 <example compact=
"compact">
5529 libbar
1 bar1 (
>=
1.0-
1)
5531 should allow the package build to work.
5535 As soon as the maintainer of
<tt>bar1
</tt> provides a
5536 correct
<file>shlibs
</file> file, you should remove this line
5537 from your
<file>debian/shlibs.local
</file> file. (You should
5538 probably also then have a versioned
<tt>Build-Depends
</tt>
5539 on
<tt>bar1
</tt> to help ensure that others do not have the
5540 same problem building your package.)
5549 <chapt id=
"opersys"><heading>The Operating System
</heading>
5552 <heading>File system hierarchy
</heading>
5556 <heading>File System Structure
</heading>
5559 The location of all installed files and directories must
5560 comply with the Filesystem Hierarchy Standard (FHS),
5561 version
2.3, with the exceptions noted below, and except
5562 where doing so would violate other terms of Debian
5563 Policy. The following exceptions to the FHS apply:
5568 The optional rules related to user specific
5569 configuration files for applications are stored in
5570 the user's home directory are relaxed. It is
5571 recommended that such files start with the
5572 '
<tt>.
</tt>' character (a
"dot file"), and if an
5573 application needs to create more than one dot file
5574 then the preferred placement is in a subdirectory
5575 with a name starting with a '.' character, (a
"dot
5576 directory"). In this case it is recommended the
5577 configuration files not start with the '.'
5583 The requirement for amd64 to use
<file>/lib64
</file>
5584 for
64 bit binaries is removed.
5589 The requirement that
5590 <file>/usr/local/share/man
</file> be
"synonymous"
5591 with
<file>/usr/local/man
</file> is relaxed to a
5596 The requirement that windowmanagers with a single
5597 configuration file call it
<file>system.*wmrc
</file>
5598 is removed, as is the restriction that the window
5599 manager subdirectory be named identically to the
5600 window manager name itself.
5605 The requirement that boot manager configuration
5606 files live in
<file>/etc
</file>, or at least are
5607 symlinked there, is relaxed to a recommendation.
5614 The version of this document referred here can be
5615 found in the
<tt>debian-policy
</tt> package or on
<url
5616 id=
"http://www.debian.org/doc/packaging-manuals/fhs/"
5617 name=
"FHS (Debian copy)"> alongside this manual (or, if
5618 you have the
<package>debian-policy
</package> installed,
5620 id=
"file:///usr/share/doc/debian-policy/fhs/" name=
"FHS
5621 (local copy)">). The
5622 latest version, which may be a more recent version, may
5624 <url id=
"http://www.pathname.com/fhs/" name=
"FHS (upstream)">.
5625 Specific questions about following the standard may be
5626 asked on the
<tt>debian-devel
</tt> mailing list, or
5627 referred to the FHS mailing list (see the
5628 <url id=
"http://www.pathname.com/fhs/" name=
"FHS web site"> for
5634 <heading>Site-specific programs
</heading>
5637 As mandated by the FHS, packages must not place any
5638 files in
<file>/usr/local
</file>, either by putting them in
5639 the file system archive to be unpacked by
<prgn>dpkg
</prgn>
5640 or by manipulating them in their maintainer scripts.
5644 However, the package may create empty directories below
5645 <file>/usr/local
</file> so that the system administrator knows
5646 where to place site-specific files. These are not
5647 directories
<em>in
</em> <file>/usr/local
</file>, but are
5648 children of directories in
<file>/usr/local
</file>. These
5649 directories (
<file>/usr/local/*/dir/
</file>)
5650 should be removed on package removal if they are
5655 Note, that this applies only to directories
<em>below
</em>
5656 <file>/usr/local
</file>, not
<em>in
</em> <file>/usr/local
</file>.
5657 Packages must not create sub-directories in the directory
5658 <file>/usr/local
</file> itself, except those listed in FHS,
5659 section
4.5. However, you may create directories below
5660 them as you wish. You must not remove any of the
5661 directories listed in
4.5, even if you created them.
5665 Since
<file>/usr/local
</file> can be mounted read-only from a
5666 remote server, these directories must be created and
5667 removed by the
<prgn>postinst
</prgn> and
<prgn>prerm
</prgn>
5668 maintainer scripts and not be included in the
5669 <file>.deb
</file> archive. These scripts must not fail if
5670 either of these operations fail.
5674 For example, the
<tt>emacsen-common
</tt> package could
5675 contain something like
5676 <example compact=
"compact">
5677 if [ ! -e /usr/local/share/emacs ]
5679 if mkdir /usr/local/share/emacs
2>/dev/null
5681 chown root:staff /usr/local/share/emacs
5682 chmod
2775 /usr/local/share/emacs
5686 in its
<prgn>postinst
</prgn> script, and
5687 <example compact=
"compact">
5688 rmdir /usr/local/share/emacs/site-lisp
2>/dev/null || true
5689 rmdir /usr/local/share/emacs
2>/dev/null || true
5691 in the
<prgn>prerm
</prgn> script. (Note that this form is
5692 used to ensure that if the script is interrupted, the
5693 directory
<file>/usr/local/share/emacs
</file> will still be
5698 If you do create a directory in
<file>/usr/local
</file> for
5699 local additions to a package, you should ensure that
5700 settings in
<file>/usr/local
</file> take precedence over the
5701 equivalents in
<file>/usr
</file>.
5705 However, because
<file>/usr/local
</file> and its contents are
5706 for exclusive use of the local administrator, a package
5707 must not rely on the presence or absence of files or
5708 directories in
<file>/usr/local
</file> for normal operation.
5712 The
<file>/usr/local
</file> directory itself and all the
5713 subdirectories created by the package should (by default) have
5714 permissions
2775 (group-writable and set-group-id) and be
5715 owned by
<tt>root:staff
</tt>.
5720 <heading>The system-wide mail directory
</heading>
5722 The system-wide mail directory is
<file>/var/mail
</file>. This
5723 directory is part of the base system and should not owned
5724 by any particular mail agents. The use of the old
5725 location
<file>/var/spool/mail
</file> is deprecated, even
5726 though the spool may still be physically located there.
5732 <heading>Users and groups
</heading>
5735 <heading>Introduction
</heading>
5737 The Debian system can be configured to use either plain or
5742 Some user ids (UIDs) and group ids (GIDs) are reserved
5743 globally for use by certain packages. Because some
5744 packages need to include files which are owned by these
5745 users or groups, or need the ids compiled into binaries,
5746 these ids must be used on any Debian system only for the
5747 purpose for which they are allocated. This is a serious
5748 restriction, and we should avoid getting in the way of
5749 local administration policies. In particular, many sites
5750 allocate users and/or local system groups starting at
100.
5754 Apart from this we should have dynamically allocated ids,
5755 which should by default be arranged in some sensible
5756 order, but the behavior should be configurable.
5760 Packages other than
<tt>base-passwd
</tt> must not modify
5761 <file>/etc/passwd
</file>,
<file>/etc/shadow
</file>,
5762 <file>/etc/group
</file> or
<file>/etc/gshadow
</file>.
5767 <heading>UID and GID classes
</heading>
5769 The UID and GID numbers are divided into classes as
5775 Globally allocated by the Debian project, the same
5776 on every Debian system. These ids will appear in
5777 the
<file>passwd
</file> and
<file>group
</file> files of all
5778 Debian systems, new ids in this range being added
5779 automatically as the
<tt>base-passwd
</tt> package is
5784 Packages which need a single statically allocated
5785 uid or gid should use one of these; their
5786 maintainers should ask the
<tt>base-passwd
</tt>
5794 Dynamically allocated system users and groups.
5795 Packages which need a user or group, but can have
5796 this user or group allocated dynamically and
5797 differently on each system, should use
<tt>adduser
5798 --system
</tt> to create the group and/or user.
5799 <prgn>adduser
</prgn> will check for the existence of
5800 the user or group, and if necessary choose an unused
5801 id based on the ranges specified in
5802 <file>adduser.conf
</file>.
5806 <tag>1000-
29999:
</tag>
5809 Dynamically allocated user accounts. By default
5810 <prgn>adduser
</prgn> will choose UIDs and GIDs for
5811 user accounts in this range, though
5812 <file>adduser.conf
</file> may be used to modify this
5817 <tag>30000-
59999:
</tag>
5822 <tag>60000-
64999:
</tag>
5825 Globally allocated by the Debian project, but only
5826 created on demand. The ids are allocated centrally
5827 and statically, but the actual accounts are only
5828 created on users' systems on demand.
5832 These ids are for packages which are obscure or
5833 which require many statically-allocated ids. These
5834 packages should check for and create the accounts in
5835 <file>/etc/passwd
</file> or
<file>/etc/group
</file> (using
5836 <prgn>adduser
</prgn> if it has this facility) if
5837 necessary. Packages which are likely to require
5838 further allocations should have a
"hole" left after
5839 them in the allocation, to give them room to
5844 <tag>65000-
65533:
</tag>
5852 User
<tt>nobody
</tt>. The corresponding gid refers
5853 to the group
<tt>nogroup
</tt>.
5860 <tt>(uid_t)(-
1) == (gid_t)(-
1)
</tt> <em>must
5861 not
</em> be used, because it is the error return
5870 <sect id=
"sysvinit">
5871 <heading>System run levels and
<file>init.d
</file> scripts
</heading>
5873 <sect1 id=
"/etc/init.d">
5874 <heading>Introduction
</heading>
5877 The
<file>/etc/init.d
</file> directory contains the scripts
5878 executed by
<prgn>init
</prgn> at boot time and when the
5879 init state (or
"runlevel") is changed (see
<manref
5880 name=
"init" section=
"8">).
5884 There are at least two different, yet functionally
5885 equivalent, ways of handling these scripts. For the sake
5886 of simplicity, this document describes only the symbolic
5887 link method. However, it must not be assumed by maintainer
5888 scripts that this method is being used, and any automated
5889 manipulation of the various runlevel behaviors by
5890 maintainer scripts must be performed using
5891 <prgn>update-rc.d
</prgn> as described below and not by
5892 manually installing or removing symlinks. For information
5893 on the implementation details of the other method,
5894 implemented in the
<tt>file-rc
</tt> package, please refer
5895 to the documentation of that package.
5899 These scripts are referenced by symbolic links in the
5900 <file>/etc/rc
<var>n
</var>.d
</file> directories. When changing
5901 runlevels,
<prgn>init
</prgn> looks in the directory
5902 <file>/etc/rc
<var>n
</var>.d
</file> for the scripts it should
5903 execute, where
<tt><var>n
</var></tt> is the runlevel that
5904 is being changed to, or
<tt>S
</tt> for the boot-up
5909 The names of the links all have the form
5910 <file>S
<var>mm
</var><var>script
</var></file> or
5911 <file>K
<var>mm
</var><var>script
</var></file> where
5912 <var>mm
</var> is a two-digit number and
<var>script
</var>
5913 is the name of the script (this should be the same as the
5914 name of the actual script in
<file>/etc/init.d
</file>).
5918 When
<prgn>init
</prgn> changes runlevel first the targets
5919 of the links whose names start with a
<tt>K
</tt> are
5920 executed, each with the single argument
<tt>stop
</tt>,
5921 followed by the scripts prefixed with an
<tt>S
</tt>, each
5922 with the single argument
<tt>start
</tt>. (The links are
5923 those in the
<file>/etc/rc
<var>n
</var>.d
</file> directory
5924 corresponding to the new runlevel.) The
<tt>K
</tt> links
5925 are responsible for killing services and the
<tt>S
</tt>
5926 link for starting services upon entering the runlevel.
5930 For example, if we are changing from runlevel
2 to
5931 runlevel
3, init will first execute all of the
<tt>K
</tt>
5932 prefixed scripts it finds in
<file>/etc/rc3.d
</file>, and then
5933 all of the
<tt>S
</tt> prefixed scripts in that directory.
5934 The links starting with
<tt>K
</tt> will cause the
5935 referred-to file to be executed with an argument of
5936 <tt>stop
</tt>, and the
<tt>S
</tt> links with an argument
5941 The two-digit number
<var>mm
</var> is used to determine
5942 the order in which to run the scripts: low-numbered links
5943 have their scripts run first. For example, the
5944 <tt>K20
</tt> scripts will be executed before the
5945 <tt>K30
</tt> scripts. This is used when a certain service
5946 must be started before another. For example, the name
5947 server
<prgn>bind
</prgn> might need to be started before
5948 the news server
<prgn>inn
</prgn> so that
<prgn>inn
</prgn>
5949 can set up its access lists. In this case, the script
5950 that starts
<prgn>bind
</prgn> would have a lower number
5951 than the script that starts
<prgn>inn
</prgn> so that it
5953 <example compact=
"compact">
5960 The two runlevels
0 (halt) and
6 (reboot) are slightly
5961 different. In these runlevels, the links with an
5962 <tt>S
</tt> prefix are still called after those with a
5963 <tt>K
</tt> prefix, but they too are called with the single
5964 argument
<tt>stop
</tt>.
5969 <heading>Writing the scripts
</heading>
5972 Packages that include daemons for system services should
5973 place scripts in
<file>/etc/init.d
</file> to start or stop
5974 services at boot time or during a change of runlevel.
5975 These scripts should be named
5976 <file>/etc/init.d/
<var>package
</var></file>, and they should
5977 accept one argument, saying what to do:
5980 <tag><tt>start
</tt></tag>
5981 <item>start the service,
</item>
5983 <tag><tt>stop
</tt></tag>
5984 <item>stop the service,
</item>
5986 <tag><tt>restart
</tt></tag>
5987 <item>stop and restart the service if it's already running,
5988 otherwise start the service
</item>
5990 <tag><tt>reload
</tt></tag>
5991 <item><p>cause the configuration of the service to be
5992 reloaded without actually stopping and restarting
5995 <tag><tt>force-reload
</tt></tag>
5996 <item>cause the configuration to be reloaded if the
5997 service supports this, otherwise restart the
6001 The
<tt>start
</tt>,
<tt>stop
</tt>,
<tt>restart
</tt>, and
6002 <tt>force-reload
</tt> options should be supported by all
6003 scripts in
<file>/etc/init.d
</file>, the
<tt>reload
</tt>
6008 The
<file>init.d
</file> scripts must ensure that they will
6009 behave sensibly (i.e., returning success and not starting
6010 multiple copies of a service) if invoked with
<tt>start
</tt>
6011 when the service is already running, or with
<tt>stop
</tt>
6012 when it isn't, and that they don't kill unfortunately-named
6013 user processes. The best way to achieve this is usually to
6014 use
<prgn>start-stop-daemon
</prgn> with the
<tt>--oknodo
</tt>
6019 If a service reloads its configuration automatically (as
6020 in the case of
<prgn>cron
</prgn>, for example), the
6021 <tt>reload
</tt> option of the
<file>init.d
</file> script
6022 should behave as if the configuration has been reloaded
6027 The
<file>/etc/init.d
</file> scripts must be treated as
6028 configuration files, either (if they are present in the
6029 package, that is, in the .deb file) by marking them as
6030 <tt>conffile
</tt>s, or, (if they do not exist in the .deb)
6031 by managing them correctly in the maintainer scripts (see
6032 <ref id=
"config-files">). This is important since we want
6033 to give the local system administrator the chance to adapt
6034 the scripts to the local system, e.g., to disable a
6035 service without de-installing the package, or to specify
6036 some special command line options when starting a service,
6037 while making sure their changes aren't lost during the next
6042 These scripts should not fail obscurely when the
6043 configuration files remain but the package has been
6044 removed, as configuration files remain on the system after
6045 the package has been removed. Only when
<prgn>dpkg
</prgn>
6046 is executed with the
<tt>--purge
</tt> option will
6047 configuration files be removed. In particular, as the
6048 <file>/etc/init.d/
<var>package
</var></file> script itself is
6049 usually a
<tt>conffile
</tt>, it will remain on the system
6050 if the package is removed but not purged. Therefore, you
6051 should include a
<tt>test
</tt> statement at the top of the
6053 <example compact=
"compact">
6054 test -f
<var>program-executed-later-in-script
</var> || exit
0
6059 Often there are some variables in the
<file>init.d
</file>
6060 scripts whose values control the behavior of the scripts,
6061 and which a system administrator is likely to want to
6062 change. As the scripts themselves are frequently
6063 <tt>conffile
</tt>s, modifying them requires that the
6064 administrator merge in their changes each time the package
6065 is upgraded and the
<tt>conffile
</tt> changes. To ease
6066 the burden on the system administrator, such configurable
6067 values should not be placed directly in the script.
6068 Instead, they should be placed in a file in
6069 <file>/etc/default
</file>, which typically will have the same
6070 base name as the
<file>init.d
</file> script. This extra file
6071 should be sourced by the script when the script runs. It
6072 must contain only variable settings and comments in SUSv3
6073 <prgn>sh
</prgn> format. It may either be a
6074 <tt>conffile
</tt> or a configuration file maintained by
6075 the package maintainer scripts. See
<ref id=
"config-files">
6080 To ensure that vital configurable values are always
6081 available, the
<file>init.d
</file> script should set default
6082 values for each of the shell variables it uses, either
6083 before sourcing the
<file>/etc/default/
</file> file or
6084 afterwards using something like the
<tt>:
6085 ${VAR:=default}
</tt> syntax. Also, the
<file>init.d
</file>
6086 script must behave sensibly and not fail if the
6087 <file>/etc/default
</file> file is deleted.
6091 <file>/var/run
</file> and
<file>/var/lock
</file> may be mounted
6092 as temporary filesystems
<footnote>
6093 For example, using the
<tt>RAMRUN
</tt> and
<tt>RAMLOCK
</tt>
6094 options in
<file>/etc/default/rcS
</file>.
6095 </footnote>, so the
<file>init.d
</file> scripts must handle this
6096 correctly. This will typically amount to creating any required
6097 subdirectories dynamically when the
<file>init.d
</file> script
6098 is run, rather than including them in the package and relying on
6099 <prgn>dpkg
</prgn> to create them.
6104 <heading>Interfacing with the initscript system
</heading>
6107 Maintainers should use the abstraction layer provided by
6108 the
<prgn>update-rc.d
</prgn> and
<prgn>invoke-rc.d
</prgn>
6109 programs to deal with initscripts in their packages'
6110 scripts such as
<prgn>postinst
</prgn>,
<prgn>prerm
</prgn>
6111 and
<prgn>postrm
</prgn>.
6115 Directly managing the /etc/rc?.d links and directly
6116 invoking the
<file>/etc/init.d/
</file> initscripts should
6117 be done only by packages providing the initscript
6118 subsystem (such as
<prgn>sysv-rc
</prgn> and
6119 <prgn>file-rc
</prgn>).
6123 <heading>Managing the links
</heading>
6126 The program
<prgn>update-rc.d
</prgn> is provided for
6127 package maintainers to arrange for the proper creation and
6128 removal of
<file>/etc/rc
<var>n
</var>.d
</file> symbolic links,
6129 or their functional equivalent if another method is being
6130 used. This may be used by maintainers in their packages'
6131 <prgn>postinst
</prgn> and
<prgn>postrm
</prgn> scripts.
6135 You must not include any
<file>/etc/rc
<var>n
</var>.d
</file>
6136 symbolic links in the actual archive or manually create or
6137 remove the symbolic links in maintainer scripts; you must
6138 use the
<prgn>update-rc.d
</prgn> program instead. (The
6139 former will fail if an alternative method of maintaining
6140 runlevel information is being used.) You must not include
6141 the
<file>/etc/rc
<var>n
</var>.d
</file> directories themselves
6142 in the archive either. (Only the
<tt>sysvinit
</tt>
6147 By default
<prgn>update-rc.d
</prgn> will start services in
6148 each of the multi-user state runlevels (
2,
3,
4, and
5)
6149 and stop them in the halt runlevel (
0), the single-user
6150 runlevel (
1) and the reboot runlevel (
6). The system
6151 administrator will have the opportunity to customize
6152 runlevels by simply adding, moving, or removing the
6153 symbolic links in
<file>/etc/rc
<var>n
</var>.d
</file> if
6154 symbolic links are being used, or by modifying
6155 <file>/etc/runlevel.conf
</file> if the
<tt>file-rc
</tt> method
6160 To get the default behavior for your package, put in your
6161 <prgn>postinst
</prgn> script
6162 <example compact=
"compact">
6163 update-rc.d
<var>package
</var> defaults
6165 and in your
<prgn>postrm
</prgn>
6166 <example compact=
"compact">
6167 if [
"$1" = purge ]; then
6168 update-rc.d
<var>package
</var> remove
6170 </example>. Note that if your package changes runlevels
6171 or priority, you may have to remove and recreate the links,
6172 since otherwise the old links may persist. Refer to the
6173 documentation of
<prgn>update-rc.d
</prgn>.
6177 This will use a default sequence number of
20. If it does
6178 not matter when or in which order the
<file>init.d
</file>
6179 script is run, use this default. If it does, then you
6180 should talk to the maintainer of the
<prgn>sysvinit
</prgn>
6181 package or post to
<tt>debian-devel
</tt>, and they will
6182 help you choose a number.
6186 For more information about using
<tt>update-rc.d
</tt>,
6187 please consult its man page
<manref name=
"update-rc.d"
6193 <heading>Running initscripts
</heading>
6195 The program
<prgn>invoke-rc.d
</prgn> is provided to make
6196 it easier for package maintainers to properly invoke an
6197 initscript, obeying runlevel and other locally-defined
6198 constraints that might limit a package's right to start,
6199 stop and otherwise manage services. This program may be
6200 used by maintainers in their packages' scripts.
6204 The package maintainer scripts must use
6205 <prgn>invoke-rc.d
</prgn> to invoke the
6206 <file>/etc/init.d/*
</file> initscripts, instead of
6207 calling them directly.
6211 By default,
<prgn>invoke-rc.d
</prgn> will pass any
6212 action requests (start, stop, reload, restart...) to the
6213 <file>/etc/init.d
</file> script, filtering out requests
6214 to start or restart a service out of its intended
6219 Most packages will simply need to change:
6220 <example compact=
"compact">/etc/init.d/
<package
>
6221 <action
></example> in their
<prgn>postinst
</prgn>
6222 and
<prgn>prerm
</prgn> scripts to:
6223 <example compact=
"compact">
6224 if which invoke-rc.d
>/dev/null
2>&1; then
6225 invoke-rc.d
<var>package
</var> <action
>
6227 /etc/init.d/
<var>package
</var> <action
>
6233 A package should register its initscript services using
6234 <prgn>update-rc.d
</prgn> before it tries to invoke them
6235 using
<prgn>invoke-rc.d
</prgn>. Invocation of
6236 unregistered services may fail.
6240 For more information about using
6241 <prgn>invoke-rc.d
</prgn>, please consult its man page
6242 <manref name=
"invoke-rc.d" section=
"8">.
6248 <heading>Boot-time initialization
</heading>
6251 There used to be another directory,
<file>/etc/rc.boot
</file>,
6252 which contained scripts which were run once per machine
6253 boot. This has been deprecated in favour of links from
6254 <file>/etc/rcS.d
</file> to files in
<file>/etc/init.d
</file> as
6255 described in
<ref id=
"/etc/init.d">. Packages must not
6256 place files in
<file>/etc/rc.boot
</file>.
6261 <heading>Example
</heading>
6264 An example on which you can base your
6265 <file>/etc/init.d
</file> scripts is found in
6266 <file>/etc/init.d/skeleton
</file>.
6273 <heading>Console messages from
<file>init.d
</file> scripts
</heading>
6276 This section describes the formats to be used for messages
6277 written to standard output by the
<file>/etc/init.d
</file>
6278 scripts. The intent is to improve the consistency of
6279 Debian's startup and shutdown look and feel. For this
6280 reason, please look very carefully at the details. We want
6281 the messages to have the same format in terms of wording,
6282 spaces, punctuation and case of letters.
6286 Here is a list of overall rules that should be used for
6287 messages generated by
<file>/etc/init.d
</file> scripts.
6293 The message should fit in one line (fewer than
80
6294 characters), start with a capital letter and end with
6295 a period (
<tt>.
</tt>) and line feed (
<tt>"\n"</tt>).
6299 If the script is performing some time consuming task in
6300 the background (not merely starting or stopping a
6301 program, for instance), an ellipsis (three dots:
6302 <tt>...
</tt>) should be output to the screen, with no
6303 leading or tailing whitespace or line feeds.
6307 The messages should appear as if the computer is telling
6308 the user what it is doing (politely :-), but should not
6309 mention
"it" directly. For example, instead of:
6310 <example compact=
"compact">
6311 I'm starting network daemons: nfsd mountd.
6313 the message should say
6314 <example compact=
"compact">
6315 Starting network daemons: nfsd mountd.
6322 <tt>init.d
</tt> script should use the following standard
6323 message formats for the situations enumerated below.
6329 <p>When daemons are started
</p>
6332 If the script starts one or more daemons, the output
6333 should look like this (a single line, no leading
6335 <example compact=
"compact">
6336 Starting
<var>description
</var>:
<var>daemon-
1</var> ...
<var>daemon-n
</var>.
6338 The
<var>description
</var> should describe the
6339 subsystem the daemon or set of daemons are part of,
6340 while
<var>daemon-
1</var> up to
<var>daemon-n
</var>
6341 denote each daemon's name (typically the file name of
6346 For example, the output of
<file>/etc/init.d/lpd
</file>
6348 <example compact=
"compact">
6349 Starting printer spooler: lpd.
6354 This can be achieved by saying
6355 <example compact=
"compact">
6356 echo -n
"Starting printer spooler: lpd"
6357 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6360 in the script. If there are more than one daemon to
6361 start, the output should look like this:
6362 <example compact=
"compact">
6363 echo -n
"Starting remote file system services:"
6364 echo -n
" nfsd"; start-stop-daemon --start --quiet nfsd
6365 echo -n
" mountd"; start-stop-daemon --start --quiet mountd
6366 echo -n
" ugidd"; start-stop-daemon --start --quiet ugidd
6369 This makes it possible for the user to see what is
6370 happening and when the final daemon has been started.
6371 Care should be taken in the placement of white spaces:
6372 in the example above the system administrators can
6373 easily comment out a line if they don't want to start
6374 a specific daemon, while the displayed message still
6380 <p>When a system parameter is being set
</p>
6383 If you have to set up different system parameters
6384 during the system boot, you should use this format:
6385 <example compact=
"compact">
6386 Setting
<var>parameter
</var> to
"<var>value</var>".
6391 You can use a statement such as the following to get
6393 <example compact=
"compact">
6394 echo
"Setting DNS domainname to \"$domainname\
"."
6399 Note that the same symbol (
<tt>"</tt>) is used for the left
6400 and right quotation marks. A grave accent (<tt>`</tt>) is
6401 not a quote character; neither is an apostrophe
6407 <p>When a daemon is stopped or restarted</p>
6410 When you stop or restart a daemon, you should issue a
6411 message identical to the startup message, except that
6412 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6413 or <tt>Restarting</tt> respectively.
6417 For example, stopping the printer daemon will look like
6419 <example compact="compact
">
6420 Stopping printer spooler: lpd.
6426 <p>When something is executed</p>
6429 There are several examples where you have to run a
6430 program at system startup or shutdown to perform a
6431 specific task, for example, setting the system's clock
6432 using <prgn>netdate</prgn> or killing all processes
6433 when the system shuts down. Your message should look
6435 <example compact="compact
">
6436 Doing something very useful...done.
6438 You should print the <tt>done.</tt> immediately after
6439 the job has been completed, so that the user is
6440 informed why they have to wait. You can get this
6442 <example compact="compact
">
6443 echo -n "Doing something very useful...
"
6452 <p>When the configuration is reloaded</p>
6455 When a daemon is forced to reload its configuration
6456 files you should use the following format:
6457 <example compact="compact
">
6458 Reloading <var>description</var> configuration...done.
6460 where <var>description</var> is the same as in the
6461 daemon starting message.
6469 <heading>Cron jobs</heading>
6472 Packages must not modify the configuration file
6473 <file>/etc/crontab</file>, and they must not modify the files in
6474 <file>/var/spool/cron/crontabs</file>.</p>
6477 If a package wants to install a job that has to be executed
6478 via cron, it should place a file with the name of the
6479 package in one or more of the following directories:
6480 <example compact="compact
">
6486 As these directory names imply, the files within them are
6487 executed on an hourly, daily, weekly, or monthly basis,
6488 respectively. The exact times are listed in
6489 <file>/etc/crontab</file>.</p>
6492 All files installed in any of these directories must be
6493 scripts (e.g., shell scripts or Perl scripts) so that they
6494 can easily be modified by the local system administrator.
6495 In addition, they must be treated as configuration files.
6499 If a certain job has to be executed at some other frequency or
6500 at a specific time, the package should install a file
6501 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6502 same syntax as <file>/etc/crontab</file> and is processed by
6503 <prgn>cron</prgn> automatically. The file must also be
6504 treated as a configuration file. (Note that entries in the
6505 <file>/etc/cron.d</file> directory are not handled by
6506 <prgn>anacron</prgn>. Thus, you should only use this
6507 directory for jobs which may be skipped if the system is not
6511 The scripts or crontab entries in these directories should
6512 check if all necessary programs are installed before they
6513 try to execute them. Otherwise, problems will arise when a
6514 package was removed but not purged since configuration files
6515 are kept on the system in this situation.</p>
6519 <heading>Menus</heading>
6522 The Debian <tt>menu</tt> package provides a standard
6523 interface between packages providing applications and
6524 <em>menu programs</em> (either X window managers or
6525 text-based menu programs such as <prgn>pdmenu</prgn>).
6529 All packages that provide applications that need not be
6530 passed any special command line arguments for normal
6531 operation should register a menu entry for those
6532 applications, so that users of the <tt>menu</tt> package
6533 will automatically get menu entries in their window
6534 managers, as well in shells like <tt>pdmenu</tt>.
6538 Menu entries should follow the current menu policy.
6542 The menu policy can be found in the <tt>menu-policy</tt>
6543 files in the <tt>debian-policy</tt> package.
6544 It is also available from the Debian web mirrors at
6545 <tt><url name="/doc/packaging-manuals/menu-policy/
"
6546 id="http://www.debian.org/doc/packaging-manuals/menu-policy/
"></tt>.
6550 Please also refer to the <em>Debian Menu System</em>
6551 documentation that comes with the <package>menu</package>
6552 package for information about how to register your
6558 <heading>Multimedia handlers</heading>
6561 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6562 is a mechanism for encoding files and data streams and
6563 providing meta-information about them, in particular their
6564 type (e.g. audio or video) and format (e.g. PNG, HTML,
6569 Registration of MIME type handlers allows programs like mail
6570 user agents and web browsers to invoke these handlers to
6571 view, edit or display MIME types they don't support directly.
6575 Packages which provide the ability to view/show/play,
6576 compose, edit or print MIME types should register themselves
6577 as such following the current MIME support policy.
6581 The MIME support policy can be found in the <tt>mime-policy</tt>
6582 files in the <tt>debian-policy</tt> package.
6583 It is also available from the Debian web mirrors at
6584 <tt><url name="/doc/packaging-manuals/mime-policy/
"
6585 id="http://www.debian.org/doc/packaging-manuals/mime-policy/
"></tt>.
6591 <heading>Keyboard configuration</heading>
6594 To achieve a consistent keyboard configuration so that all
6595 applications interpret a keyboard event the same way, all
6596 programs in the Debian distribution must be configured to
6597 comply with the following guidelines.
6601 The following keys must have the specified interpretations:
6604 <tag><tt><--</tt></tag>
6605 <item>delete the character to the left of the cursor</item>
6607 <tag><tt>Delete</tt></tag>
6608 <item>delete the character to the right of the cursor</item>
6610 <tag><tt>Control+H</tt></tag>
6611 <item>emacs: the help prefix</item>
6614 The interpretation of any keyboard events should be
6615 independent of the terminal that is used, be it a virtual
6616 console, an X terminal emulator, an rlogin/telnet session,
6621 The following list explains how the different programs
6622 should be set up to achieve this:
6628 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6632 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6636 X translations are set up to make
6637 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6638 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6639 is the vt220 escape code for the "delete character
"
6640 key). This must be done by loading the X resources
6641 using <prgn>xrdb</prgn> on all local X displays, not
6642 using the application defaults, so that the
6643 translation resources used correspond to the
6644 <prgn>xmodmap</prgn> settings.
6648 The Linux console is configured to make
6649 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6650 generate <tt>ESC [ 3 ~</tt>.
6654 X applications are configured so that <tt><</tt>
6655 deletes left, and <tt>Delete</tt> deletes right. Motif
6656 applications already work like this.
6660 Terminals should have <tt>stty erase ^?</tt> .
6664 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6665 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6666 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6670 Emacs is programmed to map <tt>KB_Backspace</tt> or
6671 the <tt>stty erase</tt> character to
6672 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6673 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6674 <tt>^H</tt> to <tt>help</tt> as always.
6678 Other applications use the <tt>stty erase</tt>
6679 character and <tt>kdch1</tt> for the two delete keys,
6680 with ASCII DEL being "delete previous character
" and
6681 <tt>kdch1</tt> being "delete character under
6689 This will solve the problem except for the following
6696 Some terminals have a <tt><--</tt> key that cannot
6697 be made to produce anything except <tt>^H</tt>. On
6698 these terminals Emacs help will be unavailable on
6699 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6700 character takes precedence in Emacs, and has been set
6701 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6702 available) can be used instead.
6706 Some operating systems use <tt>^H</tt> for <tt>stty
6707 erase</tt>. However, modern telnet versions and all
6708 rlogin versions propagate <tt>stty</tt> settings, and
6709 almost all UNIX versions honour <tt>stty erase</tt>.
6710 Where the <tt>stty</tt> settings are not propagated
6711 correctly, things can be made to work by using
6712 <tt>stty</tt> manually.
6716 Some systems (including previous Debian versions) use
6717 <prgn>xmodmap</prgn> to arrange for both
6718 <tt><--</tt> and <tt>Delete</tt> to generate
6719 <tt>KB_Delete</tt>. We can change the behavior of
6720 their X clients using the same X resources that we use
6721 to do it for our own clients, or configure our clients
6722 using their resources when things are the other way
6723 around. On displays configured like this
6724 <tt>Delete</tt> will not work, but <tt><--</tt>
6729 Some operating systems have different <tt>kdch1</tt>
6730 settings in their <tt>terminfo</tt> database for
6731 <tt>xterm</tt> and others. On these systems the
6732 <tt>Delete</tt> key will not work correctly when you
6733 log in from a system conforming to our policy, but
6734 <tt><--</tt> will.
6741 <heading>Environment variables</heading>
6744 A program must not depend on environment variables to get
6745 reasonable defaults. (That's because these environment
6746 variables would have to be set in a system-wide
6747 configuration file like <file>/etc/profile</file>, which is not
6748 supported by all shells.)
6752 If a program usually depends on environment variables for its
6753 configuration, the program should be changed to fall back to
6754 a reasonable default configuration if these environment
6755 variables are not present. If this cannot be done easily
6756 (e.g., if the source code of a non-free program is not
6757 available), the program must be replaced by a small
6758 "wrapper
" shell script which sets the environment variables
6759 if they are not already defined, and calls the original program.
6763 Here is an example of a wrapper script for this purpose:
6765 <example compact="compact
">
6767 BAR=${BAR:-/var/lib/fubar}
6769 exec /usr/lib/foo/foo "$@
"
6774 Furthermore, as <file>/etc/profile</file> is a configuration
6775 file of the <prgn>base-files</prgn> package, other packages must
6776 not put any environment variables or other commands into that
6781 <sect id="doc-base
">
6782 <heading>Registering Documents using doc-base</heading>
6785 The <package>doc-base</package> package implements a
6786 flexible mechanism for handling and presenting
6787 documentation. The recommended practice is for every Debian
6788 package that provides online documentation (other than just
6789 manual pages) to register these documents with
6790 <package>doc-base</package> by installing a
6791 <package>doc-base</package> control file via the
6792 <prgn/install-docs/ script at installation time and
6793 de-register the manuals again when the package is removed.
6796 Please refer to the documentation that comes with the
6797 <package>doc-base</package> package for information and
6806 <heading>Files</heading>
6809 <heading>Binaries</heading>
6812 Two different packages must not install programs with
6813 different functionality but with the same filenames. (The
6814 case of two programs having the same functionality but
6815 different implementations is handled via "alternatives
" or
6816 the "Conflicts
" mechanism. See <ref id="maintscripts
"> and
6817 <ref id="conflicts
"> respectively.) If this case happens,
6818 one of the programs must be renamed. The maintainers should
6819 report this to the <tt>debian-devel</tt> mailing list and
6820 try to find a consensus about which program will have to be
6821 renamed. If a consensus cannot be reached, <em>both</em>
6822 programs must be renamed.
6826 By default, when a package is being built, any binaries
6827 created should include debugging information, as well as
6828 being compiled with optimization. You should also turn on
6829 as many reasonable compilation warnings as possible; this
6830 makes life easier for porters, who can then look at build
6831 logs for possible problems. For the C programming language,
6832 this means the following compilation parameters should be
6834 <example compact="compact
">
6836 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6838 INSTALL = install -s # (or use strip on the files in debian/tmp)
6843 Note that by default all installed binaries should be stripped,
6844 either by using the <tt>-s</tt> flag to
6845 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6846 the binaries after they have been copied into
6847 <file>debian/tmp</file> but before the tree is made into a
6852 Although binaries in the build tree should be compiled with
6853 debugging information by default, it can often be difficult to
6854 debug programs if they are also subjected to compiler
6855 optimization. For this reason, it is recommended to support the
6856 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6857 (see <ref id="debianrules-options
">). This variable can contain
6858 several flags to change how a package is compiled and built.
6862 It is up to the package maintainer to decide what
6863 compilation options are best for the package. Certain
6864 binaries (such as computationally-intensive programs) will
6865 function better with certain flags (<tt>-O3</tt>, for
6866 example); feel free to use them. Please use good judgment
6867 here. Don't use flags for the sake of it; only use them
6868 if there is good reason to do so. Feel free to override
6869 the upstream author's ideas about which compilation
6870 options are best: they are often inappropriate for our
6876 <sect id="libraries
">
6877 <heading>Libraries</heading>
6880 If the package is <strong>architecture: any</strong>, then
6881 the shared library compilation and linking flags must have
6882 <tt>-fPIC</tt>, or the package shall not build on some of
6883 the supported architectures<footnote>
6885 If you are using GCC, <tt>-fPIC</tt> produces code with
6886 relocatable position independent code, which is required for
6887 most architectures to create a shared library, with i386 and
6888 perhaps some others where non position independent code is
6889 permitted in a shared library.
6892 Position independent code may have a performance penalty,
6893 especially on <tt>i386</tt>. However, in most cases the
6894 speed penalty must be measured against the memory wasted on
6895 the few architectures where non position independent code is
6898 </footnote>. Any exception to this rule must be discussed on
6899 the mailing list <em>debian-devel@lists.debian.org</em>, and
6900 a rough consensus obtained. The reasons for not compiling
6901 with <tt>-fPIC</tt> flag must be recorded in the file
6902 <tt>README.Debian</tt>, and care must be taken to either
6903 restrict the architecture or arrange for <tt>-fPIC</tt> to
6904 be used on architectures where it is required.<footnote>
6906 Some of the reasons why this might be required is if the
6907 library contains hand crafted assembly code that is not
6908 relocatable, the speed penalty is excessive for compute
6909 intensive libs, and similar reasons.
6914 As to the static libraries, the common case is not to have
6915 relocatable code, since there is no benefit, unless in specific
6916 cases; therefore the static version must not be compiled
6917 with the <tt>-fPIC</tt> flag. Any exception to this rule
6918 should be discussed on the mailing list
6919 <em>debian-devel@lists.debian.org</em>, and the reasons for
6920 compiling with the <tt>-fPIC</tt> flag must be recorded in
6921 the file <tt>README.Debian</tt>. <footnote>
6923 Some of the reasons for linking static libraries with
6924 the <tt>-fPIC</tt> flag are if, for example, one needs a
6925 Perl API for a library that is under rapid development,
6926 and has an unstable API, so shared libraries are
6927 pointless at this phase of the library's development. In
6928 that case, since Perl needs a library with relocatable
6929 code, it may make sense to create a static library with
6930 relocatable code. Another reason cited is if you are
6931 distilling various libraries into a common shared
6932 library, like <tt>mklibs</tt> does in the Debian
6938 In other words, if both a shared and a static library is
6939 being built, each source unit (<tt>*.c</tt>, for example,
6940 for C files) will need to be compiled twice, for the normal
6944 You must specify the gcc option <tt>-D_REENTRANT</tt>
6945 when building a library (either static or shared) to make
6946 the library compatible with LinuxThreads.
6950 Although not enforced by the build tools, shared libraries
6951 must be linked against all libraries that they use symbols from
6952 in the same way that binaries are. This ensures the correct
6953 functioning of the <qref id="sharedlibs-shlibdeps
">shlibs</qref>
6954 system and guarantees that all libraries can be safely opened
6955 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6956 option <tt>-Wl,-z,defs</tt> when building a shared library.
6957 Since this option enforces symbol resolution at build time,
6958 a missing library reference will be caught early as a fatal
6963 All installed shared libraries should be stripped with
6964 <example compact="compact
">
6965 strip --strip-unneeded <var>your-lib</var>
6967 (The option <tt>--strip-unneeded</tt> makes
6968 <prgn>strip</prgn> remove only the symbols which aren't
6969 needed for relocation processing.) Shared libraries can
6970 function perfectly well when stripped, since the symbols for
6971 dynamic linking are in a separate part of the ELF object
6973 You might also want to use the options
6974 <tt>--remove-section=.comment</tt> and
6975 <tt>--remove-section=.note</tt> on both shared libraries
6976 and executables, and <tt>--strip-debug</tt> on static
6982 Note that under some circumstances it may be useful to
6983 install a shared library unstripped, for example when
6984 building a separate package to support debugging.
6988 Shared object files (often <file>.so</file> files) that are not
6989 public libraries, that is, they are not meant to be linked
6990 to by third party executables (binaries of other packages),
6991 should be installed in subdirectories of the
6992 <file>/usr/lib</file> directory. Such files are exempt from the
6993 rules that govern ordinary shared libraries, except that
6994 they must not be installed executable and should be
6996 A common example are the so-called "plug-ins
",
6997 internal shared objects that are dynamically loaded by
6998 programs using <manref name="dlopen
" section="3">.
7003 Packages containing shared libraries that may be linked to
7004 by other packages' binaries, but which for some
7005 <em>compelling</em> reason can not be installed in
7006 <file>/usr/lib</file> directory, may install the shared library
7007 files in subdirectories of the <file>/usr/lib</file> directory,
7008 in which case they should arrange to add that directory in
7009 <file>/etc/ld.so.conf</file> in the package's post-installation
7010 script, and remove it in the package's post-removal script.
7014 An ever increasing number of packages are using
7015 <prgn>libtool</prgn> to do their linking. The latest GNU
7016 libtools (>= 1.3a) can take advantage of the metadata in the
7017 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7018 files). The main advantage of <prgn>libtool</prgn>'s
7019 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7020 store and subsequently access metadata with respect to the
7021 libraries it builds. <prgn>libtool</prgn> will search for
7022 those files, which contain a lot of useful information about
7023 a library (such as library dependency information for static
7024 linking). Also, they're <em>essential</em> for programs
7025 using <tt>libltdl</tt>.<footnote>
7026 Although <prgn>libtool</prgn> is fully capable of
7027 linking against shared libraries which don't have
7028 <tt>.la</tt> files, as it is a mere shell script it can
7029 add considerably to the build time of a
7030 <prgn>libtool</prgn>-using package if that shell script
7031 has to derive all this information from first principles
7032 for each library every time it is linked. With the
7033 advent of <prgn>libtool</prgn> version 1.4 (and to a
7034 lesser extent <prgn>libtool</prgn> version 1.3), the
7035 <file>.la</file> files also store information about
7036 inter-library dependencies which cannot necessarily be
7037 derived after the <file>.la</file> file is deleted.
7042 Packages that use <prgn>libtool</prgn> to create shared
7043 libraries should include the <file>.la</file> files in the
7044 <tt>-dev</tt> package, unless the package relies on
7045 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7046 the <tt>.la</tt> files must go in the run-time library
7051 You must make sure that you use only released versions of
7052 shared libraries to build your packages; otherwise other
7053 users will not be able to run your binaries
7054 properly. Producing source packages that depend on
7055 unreleased compilers is also usually a bad
7062 <heading>Shared libraries</heading>
7064 This section has moved to <ref id="sharedlibs
">.
7070 <heading>Scripts</heading>
7073 All command scripts, including the package maintainer
7074 scripts inside the package and used by <prgn>dpkg</prgn>,
7075 should have a <tt>#!</tt> line naming the shell to be used
7080 In the case of Perl scripts this should be
7081 <tt>#!/usr/bin/perl</tt>.
7085 When scripts are installed into a directory in the system
7086 PATH, the script name should not include an extension such
7087 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7088 language currently used to implement it.
7091 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7092 should almost certainly start with <tt>set -e</tt> so that
7093 errors are detected. Every script should use
7094 <tt>set -e</tt> or check the exit status of <em>every</em>
7099 Scripts may assume that <file>/bin/sh</file> implements the
7100 SUSv3 Shell Command Language<footnote>
7101 Single UNIX Specification, version 3, which is also IEEE
7102 1003.1-2004 (POSIX), and is available on the World Wide Web
7103 from <url id="http://www.unix.org/version3/online.html
"
7104 name="The Open Group
"> after free
7105 registration.</footnote>
7106 plus the following additional features not mandated by
7108 These features are in widespread use in the Linux community
7109 and are implemented in all of bash, dash, and ksh, the most
7110 common shells users may wish to use as <file>/bin/sh</file>.
7113 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7114 must not generate a newline.</item>
7115 <item><tt>test</tt>, if implemented as a shell built-in, must
7116 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7118 <item><tt>local</tt> to create a scoped variable must be
7119 supported, including listing multiple variables in a single
7120 local command and assigning a value to a variable at the
7121 same time as localizing it. <tt>local</tt> may or
7122 may not preserve the variable value from an outer scope if
7123 no assignment is present. Uses such as:
7127 # ... use a, b, c, d ...
7130 must be supported and must set the value of <tt>c</tt> to
7134 If a shell script requires non-SUSv3 features from the shell
7135 interpreter other than those listed above, the appropriate shell
7136 must be specified in the first line of the script (e.g.,
7137 <tt>#!/bin/bash</tt>) and the package must depend on the package
7138 providing the shell (unless the shell package is marked
7139 "Essential
", as in the case of <prgn>bash</prgn>).
7143 You may wish to restrict your script to SUSv3 features plus the
7144 above set when possible so that it may use <file>/bin/sh</file>
7145 as its interpreter. If your script works with <prgn>dash</prgn>
7146 (originally called <prgn>ash</prgn>), it probably complies with
7147 the above requirements, but if you are in doubt, use
7148 <file>/bin/bash</file>.
7152 Perl scripts should check for errors when making any
7153 system calls, including <tt>open</tt>, <tt>print</tt>,
7154 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7158 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7159 scripting languages. See <em>Csh Programming Considered
7160 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7161 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/
">.
7162 If an upstream package comes with <prgn>csh</prgn> scripts
7163 then you must make sure that they start with
7164 <tt>#!/bin/csh</tt> and make your package depend on the
7165 <prgn>c-shell</prgn> virtual package.
7169 Any scripts which create files in world-writeable
7170 directories (e.g., in <file>/tmp</file>) must use a
7171 mechanism which will fail atomically if a file with the same
7172 name already exists.
7176 The Debian base system provides the <prgn>tempfile</prgn>
7177 and <prgn>mktemp</prgn> utilities for use by scripts for
7184 <heading>Symbolic links</heading>
7187 In general, symbolic links within a top-level directory
7188 should be relative, and symbolic links pointing from one
7189 top-level directory into another should be absolute. (A
7190 top-level directory is a sub-directory of the root
7191 directory <file>/</file>.)
7195 In addition, symbolic links should be specified as short as
7196 possible, i.e., link targets like <file>foo/../bar</file> are
7201 Note that when creating a relative link using
7202 <prgn>ln</prgn> it is not necessary for the target of the
7203 link to exist relative to the working directory you're
7204 running <prgn>ln</prgn> from, nor is it necessary to change
7205 directory to the directory where the link is to be made.
7206 Simply include the string that should appear as the target
7207 of the link (this will be a pathname relative to the
7208 directory in which the link resides) as the first argument
7213 For example, in your <prgn>Makefile</prgn> or
7214 <file>debian/rules</file>, you can do things like:
7215 <example compact="compact
">
7216 ln -fs gcc $(prefix)/bin/cc
7217 ln -fs gcc debian/tmp/usr/bin/cc
7218 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7219 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7224 A symbolic link pointing to a compressed file should always
7225 have the same file extension as the referenced file. (For
7226 example, if a file <file>foo.gz</file> is referenced by a
7227 symbolic link, the filename of the link has to end with
7228 "<file>.gz
</file>" too, as in <file>bar.gz</file>.)
7233 <heading>Device files</heading>
7236 Packages must not include device files in the package file
7241 If a package needs any special device files that are not
7242 included in the base system, it must call
7243 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7244 after notifying the user<footnote>
7245 This notification could be done via a (low-priority)
7246 debconf message, or an echo (printf) statement.
7251 Packages must not remove any device files in the
7252 <prgn>postrm</prgn> or any other script. This is left to the
7253 system administrator.
7257 Debian uses the serial devices
7258 <file>/dev/ttyS*</file>. Programs using the old
7259 <file>/dev/cu*</file> devices should be changed to use
7260 <file>/dev/ttyS*</file>.
7264 <sect id="config-files
">
7265 <heading>Configuration files</heading>
7268 <heading>Definitions</heading>
7272 <tag>configuration file</tag>
7274 A file that affects the operation of a program, or
7275 provides site- or host-specific information, or
7276 otherwise customizes the behavior of a program.
7277 Typically, configuration files are intended to be
7278 modified by the system administrator (if needed or
7279 desired) to conform to local policy or to provide
7280 more useful site-specific behavior.
7283 <tag><tt>conffile</tt></tag>
7285 A file listed in a package's <tt>conffiles</tt>
7286 file, and is treated specially by <prgn>dpkg</prgn>
7287 (see <ref id="configdetails
">).
7293 The distinction between these two is important; they are
7294 not interchangeable concepts. Almost all
7295 <tt>conffile</tt>s are configuration files, but many
7296 configuration files are not <tt>conffiles</tt>.
7300 As noted elsewhere, <file>/etc/init.d</file> scripts,
7301 <file>/etc/default</file> files, scripts installed in
7302 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7303 configuration installed in <file>/etc/cron.d</file> must be
7304 treated as configuration files. In general, any script that
7305 embeds configuration information is de-facto a configuration
7306 file and should be treated as such.
7311 <heading>Location</heading>
7314 Any configuration files created or used by your package
7315 must reside in <file>/etc</file>. If there are several,
7316 consider creating a subdirectory of <file>/etc</file>
7317 named after your package.
7321 If your package creates or uses configuration files
7322 outside of <file>/etc</file>, and it is not feasible to modify
7323 the package to use <file>/etc</file> directly, put the files
7324 in <file>/etc</file> and create symbolic links to those files
7325 from the location that the package requires.
7330 <heading>Behavior</heading>
7333 Configuration file handling must conform to the following
7335 <list compact="compact
">
7337 local changes must be preserved during a package
7341 configuration files must be preserved when the
7342 package is removed, and only deleted when the
7349 The easy way to achieve this behavior is to make the
7350 configuration file a <tt>conffile</tt>. This is
7351 appropriate only if it is possible to distribute a default
7352 version that will work for most installations, although
7353 some system administrators may choose to modify it. This
7354 implies that the default version will be part of the
7355 package distribution, and must not be modified by the
7356 maintainer scripts during installation (or at any other
7361 In order to ensure that local changes are preserved
7362 correctly, no package may contain or make hard links to
7363 conffiles.<footnote>
7364 Rationale: There are two problems with hard links.
7365 The first is that some editors break the link while
7366 editing one of the files, so that the two files may
7367 unwittingly become unlinked and different. The second
7368 is that <prgn>dpkg</prgn> might break the hard link
7369 while upgrading <tt>conffile</tt>s.
7374 The other way to do it is via the maintainer scripts. In
7375 this case, the configuration file must not be listed as a
7376 <tt>conffile</tt> and must not be part of the package
7377 distribution. If the existence of a file is required for
7378 the package to be sensibly configured it is the
7379 responsibility of the package maintainer to provide
7380 maintainer scripts which correctly create, update and
7381 maintain the file and remove it on purge. (See <ref
7382 id="maintainerscripts
"> for more information.) These
7383 scripts must be idempotent (i.e., must work correctly if
7384 <prgn>dpkg</prgn> needs to re-run them due to errors
7385 during installation or removal), must cope with all the
7386 variety of ways <prgn>dpkg</prgn> can call maintainer
7387 scripts, must not overwrite or otherwise mangle the user's
7388 configuration without asking, must not ask unnecessary
7389 questions (particularly during upgrades), and must
7390 otherwise be good citizens.
7394 The scripts are not required to configure every possible
7395 option for the package, but only those necessary to get
7396 the package running on a given system. Ideally the
7397 sysadmin should not have to do any configuration other
7398 than that done (semi-)automatically by the
7399 <prgn>postinst</prgn> script.
7403 A common practice is to create a script called
7404 <file><var>package</var>-configure</file> and have the
7405 package's <prgn>postinst</prgn> call it if and only if the
7406 configuration file does not already exist. In certain
7407 cases it is useful for there to be an example or template
7408 file which the maintainer scripts use. Such files should
7409 be in <file>/usr/share/<var>package</var></file> or
7410 <file>/usr/lib/<var>package</var></file> (depending on whether
7411 they are architecture-independent or not). There should
7412 be symbolic links to them from
7413 <file>/usr/share/doc/<var>package</var>/examples</file> if
7414 they are examples, and should be perfectly ordinary
7415 <prgn>dpkg</prgn>-handled files (<em>not</em>
7416 configuration files).
7420 These two styles of configuration file handling must
7421 not be mixed, for that way lies madness:
7422 <prgn>dpkg</prgn> will ask about overwriting the file
7423 every time the package is upgraded.
7428 <heading>Sharing configuration files</heading>
7431 Packages which specify the same file as a
7432 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7433 with each other. (This is an instance of the general rule
7434 about not sharing files. Note that neither alternatives
7435 nor diversions are likely to be appropriate in this case;
7436 in particular, <prgn>dpkg</prgn> does not handle diverted
7437 <tt>conffile</tt>s well.)
7441 The maintainer scripts must not alter a <tt>conffile</tt>
7442 of <em>any</em> package, including the one the scripts
7447 If two or more packages use the same configuration file
7448 and it is reasonable for both to be installed at the same
7449 time, one of these packages must be defined as
7450 <em>owner</em> of the configuration file, i.e., it will be
7451 the package which handles that file as a configuration
7452 file. Other packages that use the configuration file must
7453 depend on the owning package if they require the
7454 configuration file to operate. If the other package will
7455 use the configuration file if present, but is capable of
7456 operating without it, no dependency need be declared.
7460 If it is desirable for two or more related packages to
7461 share a configuration file <em>and</em> for all of the
7462 related packages to be able to modify that configuration
7463 file, then the following should be done:
7464 <enumlist compact="compact
">
7466 One of the related packages (the "owning
" package)
7467 will manage the configuration file with maintainer
7468 scripts as described in the previous section.
7471 The owning package should also provide a program
7472 that the other packages may use to modify the
7476 The related packages must use the provided program
7477 to make any desired modifications to the
7478 configuration file. They should either depend on
7479 the core package to guarantee that the configuration
7480 modifier program is available or accept gracefully
7481 that they cannot modify the configuration file if it
7482 is not. (This is in addition to the fact that the
7483 configuration file may not even be present in the
7490 Sometimes it's appropriate to create a new package which
7491 provides the basic infrastructure for the other packages
7492 and which manages the shared configuration files. (The
7493 <tt>sgml-base</tt> package is a good example.)
7498 <heading>User configuration files ("dotfiles
")</heading>
7501 The files in <file>/etc/skel</file> will automatically be
7502 copied into new user accounts by <prgn>adduser</prgn>.
7503 No other program should reference the files in
7504 <file>/etc/skel</file>.
7508 Therefore, if a program needs a dotfile to exist in
7509 advance in <file>$HOME</file> to work sensibly, that dotfile
7510 should be installed in <file>/etc/skel</file> and treated as a
7515 However, programs that require dotfiles in order to
7516 operate sensibly are a bad thing, unless they do create
7517 the dotfiles themselves automatically.
7521 Furthermore, programs should be configured by the Debian
7522 default installation to behave as closely to the upstream
7523 default behavior as possible.
7527 Therefore, if a program in a Debian package needs to be
7528 configured in some way in order to operate sensibly, that
7529 should be done using a site-wide configuration file placed
7530 in <file>/etc</file>. Only if the program doesn't support a
7531 site-wide default configuration and the package maintainer
7532 doesn't have time to add it may a default per-user file be
7533 placed in <file>/etc/skel</file>.
7537 <file>/etc/skel</file> should be as empty as we can make it.
7538 This is particularly true because there is no easy (or
7539 necessarily desirable) mechanism for ensuring that the
7540 appropriate dotfiles are copied into the accounts of
7541 existing users when a package is installed.
7547 <heading>Log files</heading>
7549 Log files should usually be named
7550 <file>/var/log/<var>package</var>.log</file>. If you have many
7551 log files, or need a separate directory for permission
7552 reasons (<file>/var/log</file> is writable only by
7553 <file>root</file>), you should usually create a directory named
7554 <file>/var/log/<var>package</var></file> and place your log
7559 Log files must be rotated occasionally so that they don't
7560 grow indefinitely; the best way to do this is to drop a log
7561 rotation configuration file into the directory
7562 <file>/etc/logrotate.d</file> and use the facilities provided by
7563 logrotate.<footnote>
7565 The traditional approach to log files has been to set up
7566 <em>ad hoc</em> log rotation schemes using simple shell
7567 scripts and cron. While this approach is highly
7568 customizable, it requires quite a lot of sysadmin work.
7569 Even though the original Debian system helped a little
7570 by automatically installing a system which can be used
7571 as a template, this was deemed not enough.
7575 The use of <prgn>logrotate</prgn>, a program developed
7576 by Red Hat, is better, as it centralizes log management.
7577 It has both a configuration file
7578 (<file>/etc/logrotate.conf</file>) and a directory where
7579 packages can drop their individual log rotation
7580 configurations (<file>/etc/logrotate.d</file>).
7583 Here is a good example for a logrotate config
7584 file (for more information see <manref name="logrotate
"
7586 <example compact="compact
">
7587 /var/log/foo/*.log {
7592 /etc/init.d/foo force-reload
7596 This rotates all files under <file>/var/log/foo</file>, saves 12
7597 compressed generations, and forces the daemon to reload its
7598 configuration information after the log rotation.
7602 Log files should be removed when the package is
7603 purged (but not when it is only removed). This should be
7604 done by the <prgn>postrm</prgn> script when it is called
7605 with the argument <tt>purge</tt> (see <ref
7606 id="removedetails
">).
7611 <heading>Permissions and owners</heading>
7614 The rules in this section are guidelines for general use.
7615 If necessary you may deviate from the details below.
7616 However, if you do so you must make sure that what is done
7617 is secure and you should try to be as consistent as possible
7618 with the rest of the system. You should probably also
7619 discuss it on <prgn>debian-devel</prgn> first.
7623 Files should be owned by <tt>root:root</tt>, and made
7624 writable only by the owner and universally readable (and
7625 executable, if appropriate), that is mode 644 or 755.
7629 Directories should be mode 755 or (for group-writability)
7630 mode 2775. The ownership of the directory should be
7631 consistent with its mode: if a directory is mode 2775, it
7632 should be owned by the group that needs write access to
7635 When a package is upgraded, and the owner or permissions
7636 of a file included in the package has changed, dpkg
7637 arranges for the ownership and permissions to be
7638 correctly set upon installation. However, this does not
7639 extend to directories; the permissions and ownership of
7640 directories already on the system does not change on
7641 install or upgrade of packages. This makes sense, since
7642 otherwise common directories like <tt>/usr</tt> would
7643 always be in flux. To correctly change permissions of a
7644 directory the package owns, explicit action is required,
7645 usually in the <tt>postinst</tt> script. Care must be
7646 taken to handle downgrades as well, in that case.
7653 Setuid and setgid executables should be mode 4755 or 2755
7654 respectively, and owned by the appropriate user or group.
7655 They should not be made unreadable (modes like 4711 or
7656 2711 or even 4111); doing so achieves no extra security,
7657 because anyone can find the binary in the freely available
7658 Debian package; it is merely inconvenient. For the same
7659 reason you should not restrict read or execute permissions
7660 on non-set-id executables.
7664 Some setuid programs need to be restricted to particular
7665 sets of users, using file permissions. In this case they
7666 should be owned by the uid to which they are set-id, and by
7667 the group which should be allowed to execute them. They
7668 should have mode 4754; again there is no point in making
7669 them unreadable to those users who must not be allowed to
7674 It is possible to arrange that the system administrator can
7675 reconfigure the package to correspond to their local
7676 security policy by changing the permissions on a binary:
7677 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7678 described below.<footnote>
7679 Ordinary files installed by <prgn>dpkg</prgn> (as
7680 opposed to <tt>conffile</tt>s and other similar objects)
7681 normally have their permissions reset to the distributed
7682 permissions when the package is reinstalled. However,
7683 the use of <prgn>dpkg-statoverride</prgn> overrides this
7684 default behavior. If you use this method, you should
7685 remember to describe <prgn>dpkg-statoverride</prgn> in
7686 the package documentation; being a relatively new
7687 addition to Debian, it is probably not yet well-known.
7689 Another method you should consider is to create a group for
7690 people allowed to use the program(s) and make any setuid
7691 executables executable only by that group.
7695 If you need to create a new user or group for your package
7696 there are two possibilities. Firstly, you may need to
7697 make some files in the binary package be owned by this
7698 user or group, or you may need to compile the user or
7699 group id (rather than just the name) into the binary
7700 (though this latter should be avoided if possible, as in
7701 this case you need a statically allocated id).</p>
7704 If you need a statically allocated id, you must ask for a
7705 user or group id from the <tt>base-passwd</tt> maintainer,
7706 and must not release the package until you have been
7707 allocated one. Once you have been allocated one you must
7708 either make the package depend on a version of the
7709 <tt>base-passwd</tt> package with the id present in
7710 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7711 your package to create the user or group itself with the
7712 correct id (using <tt>adduser</tt>) in its
7713 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7714 the <prgn>postinst</prgn> is to be preferred if it is
7715 possible, otherwise a pre-dependency will be needed on the
7716 <tt>adduser</tt> package.)
7720 On the other hand, the program might be able to determine
7721 the uid or gid from the user or group name at runtime, so
7722 that a dynamically allocated id can be used. In this case
7723 you should choose an appropriate user or group name,
7724 discussing this on <prgn>debian-devel</prgn> and checking
7725 with the <package/base-passwd/ maintainer that it is unique and that
7726 they do not wish you to use a statically allocated id
7727 instead. When this has been checked you must arrange for
7728 your package to create the user or group if necessary using
7729 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7730 <prgn>postinst</prgn> script (again, the latter is to be
7731 preferred if it is possible).
7735 Note that changing the numeric value of an id associated
7736 with a name is very difficult, and involves searching the
7737 file system for all appropriate files. You need to think
7738 carefully whether a static or dynamic id is required, since
7739 changing your mind later will cause problems.
7742 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7744 This section is not intended as policy, but as a
7745 description of the use of <prgn>dpkg-statoverride</prgn>.
7749 If a system administrator wishes to have a file (or
7750 directory or other such thing) installed with owner and
7751 permissions different from those in the distributed Debian
7752 package, they can use the <prgn>dpkg-statoverride</prgn>
7753 program to instruct <prgn>dpkg</prgn> to use the different
7754 settings every time the file is installed. Thus the
7755 package maintainer should distribute the files with their
7756 normal permissions, and leave it for the system
7757 administrator to make any desired changes. For example, a
7758 daemon which is normally required to be setuid root, but
7759 in certain situations could be used without being setuid,
7760 should be installed setuid in the <tt>.deb</tt>. Then the
7761 local system administrator can change this if they wish.
7762 If there are two standard ways of doing it, the package
7763 maintainer can use <tt>debconf</tt> to find out the
7764 preference, and call <prgn>dpkg-statoverride</prgn> in the
7765 maintainer script if necessary to accommodate the system
7766 administrator's choice. Care must be taken during
7767 upgrades to not override an existing setting.
7771 Given the above, <prgn>dpkg-statoverride</prgn> is
7772 essentially a tool for system administrators and would not
7773 normally be needed in the maintainer scripts. There is
7774 one type of situation, though, where calls to
7775 <prgn>dpkg-statoverride</prgn> would be needed in the
7776 maintainer scripts, and that involves packages which use
7777 dynamically allocated user or group ids. In such a
7778 situation, something like the following idiom can be very
7779 helpful in the package's <prgn>postinst</prgn>, where
7780 <tt>sysuser</tt> is a dynamically allocated id:
7782 for i in /usr/bin/foo /usr/sbin/bar
7784 # only do something when no setting exists
7785 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7787 #include: debconf processing, question about foo and bar
7788 if [ "$RET
" = "true
" ] ; then
7789 dpkg-statoverride --update --add sysuser root 4755 $i
7794 The corresponding <tt>dpkg-statoverride --remove</tt>
7795 calls can then be made unconditionally when the package is
7803 <chapt id="customized-programs
">
7804 <heading>Customized programs</heading>
7806 <sect id="arch-spec
">
7807 <heading>Architecture specification strings</heading>
7810 If a program needs to specify an <em>architecture specification
7811 string</em> in some place, it should select one of the
7812 strings provided by <tt>dpkg-architecture -L</tt>. The
7813 strings are in the format
7814 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7815 is sometimes elided, as when the OS is Linux.<footnote>
7816 <p>Currently, the strings are:
7817 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7818 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7819 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7820 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7821 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7822 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7823 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7824 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7825 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7826 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7827 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7828 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7829 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7830 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7831 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7832 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7833 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7834 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7835 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7836 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7837 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7838 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7839 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7840 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7841 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7842 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7843 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7844 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7845 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7846 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7847 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7848 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7849 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7850 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7851 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7852 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7853 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7859 Note that we don't want to use
7860 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7861 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7862 since this would make our programs incompatible with other
7863 Linux distributions. We also don't use something like
7864 <tt><var>arch</var>-unknown-linux</tt>, since the
7865 <tt>unknown</tt> does not look very good.
7870 <heading>Daemons</heading>
7873 The configuration files <file>/etc/services</file>,
7874 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7875 by the <prgn>netbase</prgn> package and must not be modified
7880 If a package requires a new entry in one of these files, the
7881 maintainer should get in contact with the
7882 <prgn>netbase</prgn> maintainer, who will add the entries
7883 and release a new version of the <prgn>netbase</prgn>
7888 The configuration file <file>/etc/inetd.conf</file> must not be
7889 modified by the package's scripts except via the
7890 <prgn>update-inetd</prgn> script or the
7891 <file>DebianNet.pm</file> Perl module. See their documentation
7892 for details on how to add entries.
7896 If a package wants to install an example entry into
7897 <file>/etc/inetd.conf</file>, the entry must be preceded with
7898 exactly one hash character (<tt>#</tt>). Such lines are
7899 treated as "commented out by user
" by the
7900 <prgn>update-inetd</prgn> script and are not changed or
7901 activated during package updates.
7906 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7910 Some programs need to create pseudo-ttys. This should be done
7911 using Unix98 ptys if the C library supports it. The resulting
7912 program must not be installed setuid root, unless that
7913 is required for other functionality.
7917 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7918 <file>/var/log/lastlog</file> must be installed writable by
7919 group <tt>utmp</tt>. Programs which need to modify those
7920 files must be installed setgid <tt>utmp</tt>.
7925 <heading>Editors and pagers</heading>
7928 Some programs have the ability to launch an editor or pager
7929 program to edit or display a text document. Since there are
7930 lots of different editors and pagers available in the Debian
7931 distribution, the system administrator and each user should
7932 have the possibility to choose their preferred editor and
7937 In addition, every program should choose a good default
7938 editor/pager if none is selected by the user or system
7943 Thus, every program that launches an editor or pager must
7944 use the EDITOR or PAGER environment variable to determine
7945 the editor or pager the user wishes to use. If these
7946 variables are not set, the programs <file>/usr/bin/editor</file>
7947 and <file>/usr/bin/pager</file> should be used, respectively.
7951 These two files are managed through the <prgn>dpkg</prgn>
7952 "alternatives
" mechanism. Thus every package providing an
7953 editor or pager must call the
7954 <prgn>update-alternatives</prgn> script to register these
7959 If it is very hard to adapt a program to make use of the
7960 EDITOR or PAGER variables, that program may be configured to
7961 use <file>/usr/bin/sensible-editor</file> and
7962 <file>/usr/bin/sensible-pager</file> as the editor or pager
7963 program respectively. These are two scripts provided in the
7964 Debian base system that check the EDITOR and PAGER variables
7965 and launch the appropriate program, and fall back to
7966 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7967 variable is not set.
7971 A program may also use the VISUAL environment variable to
7972 determine the user's choice of editor. If it exists, it
7973 should take precedence over EDITOR. This is in fact what
7974 <file>/usr/bin/sensible-editor</file> does.
7978 It is not required for a package to depend on
7979 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7980 package to provide such virtual packages.<footnote>
7981 The Debian base system already provides an editor and a
7987 <sect id="web-appl
">
7988 <heading>Web servers and applications</heading>
7991 This section describes the locations and URLs that should
7992 be used by all web servers and web applications in the
7999 Cgi-bin executable files are installed in the
8001 <example compact="compact
">
8002 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8004 and should be referred to as
8005 <example compact="compact
">
8006 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8012 <p>Access to HTML documents</p>
8015 HTML documents for a package are stored in
8016 <file>/usr/share/doc/<var>package</var></file>
8017 and can be referred to as
8018 <example compact="compact
">
8019 http://localhost/doc/<var>package</var>/<var>filename</var>
8024 The web server should restrict access to the document
8025 tree so that only clients on the same host can read
8026 the documents. If the web server does not support such
8027 access controls, then it should not provide access at
8028 all, or ask about providing access during installation.
8033 <p>Access to images</p>
8035 It is recommended that images for a package be stored
8036 in <tt>/usr/share/images/<var>package</var></tt> and
8037 may be referred to through an alias <tt>/images/</tt>
8040 http://localhost/images/<package>/<filename>
8047 <p>Web Document Root</p>
8050 Web Applications should try to avoid storing files in
8051 the Web Document Root. Instead they should use the
8052 /usr/share/doc/<var>package</var> directory for
8053 documents and register the Web Application via the
8054 <package>doc-base</package> package. If access to the
8055 web document root is unavoidable then use
8056 <example compact="compact
">
8059 as the Document Root. This might be just a symbolic
8060 link to the location where the system administrator
8061 has put the real document root.
8064 <item><p>Providing httpd and/or httpd-cgi</p>
8066 All web servers should provide the virtual package
8067 <tt>httpd</tt>. If a web server has CGI support it should
8068 provide <tt>httpd-cgi</tt> additionally.
8071 All web applications which do not contain CGI scripts should
8072 depend on <tt>httpd</tt>, all those web applications which
8073 <tt>do</tt> contain CGI scripts, should depend on
8081 <sect id="mail-transport-agents
">
8082 <heading>Mail transport, delivery and user agents</heading>
8085 Debian packages which process electronic mail, whether mail
8086 user agents (MUAs) or mail transport agents (MTAs), must
8087 ensure that they are compatible with the configuration
8088 decisions below. Failure to do this may result in lost
8089 mail, broken <tt>From:</tt> lines, and other serious brain
8094 The mail spool is <file>/var/mail</file> and the interface to
8095 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8096 the FHS). On older systems, the mail spool may be
8097 physically located in <file>/var/spool/mail</file>, but all
8098 access to the mail spool should be via the
8099 <file>/var/mail</file> symlink. The mail spool is part of the
8100 base system and not part of the MTA package.
8104 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8105 programs (such as IMAP daemons) must lock the mailbox in an
8106 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8107 be combined with dot locking. To avoid deadlocks, a program
8108 should use <tt>fcntl()</tt> first and dot locking after
8109 this, or alternatively implement the two locking methods in
8110 a non blocking way<footnote>
8111 If it is not possible to establish both locks, the
8112 system shouldn't wait for the second lock to be
8113 established, but remove the first lock, wait a (random)
8114 time, and start over locking again.
8115 </footnote>. Using the functions <tt>maillock</tt> and
8116 <tt>mailunlock</tt> provided by the
8117 <tt>liblockfile*</tt><footnote>
8118 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8119 to use these functions.
8120 </footnote> packages is the recommended way to realize this.
8124 Mailboxes are generally either mode 600 and owned by
8125 <var>user</var> or mode 660 and owned by
8126 <tt><var>user</var>:mail</tt><footnote>
8127 There are two traditional permission schemes for mail spools:
8128 mode 600 with all mail delivery done by processes running as
8129 the destination user, or mode 660 and owned by group mail with
8130 mail delivery done by a process running as a system user in
8131 group mail. Historically, Debian required mode 660 mail
8132 spools to enable the latter model, but that model has become
8133 increasingly uncommon and the principle of least privilege
8134 indicates that mail systems that use the first model should
8135 use permissions of 600. If delivery to programs is permitted,
8136 it's easier to keep the mail system secure if the delivery
8137 agent runs as the destination user. Debian Policy therefore
8138 permits either scheme.
8139 </footnote>. The local system administrator may choose a
8140 different permission scheme; packages should not make
8141 assumptions about the permission and ownership of mailboxes
8142 unless required (such as when creating a new mailbox). A MUA
8143 may remove a mailbox (unless it has nonstandard permissions) in
8144 which case the MTA or another MUA must recreate it if needed.
8148 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8149 be setgid mail to do the locking mentioned above (and
8150 must obviously avoid accessing other users' mailboxes
8151 using this privilege).</p>
8154 <file>/etc/aliases</file> is the source file for the system mail
8155 aliases (e.g., postmaster, usenet, etc.), it is the one
8156 which the sysadmin and <prgn>postinst</prgn> scripts may
8157 edit. After <file>/etc/aliases</file> is edited the program or
8158 human editing it must call <prgn>newaliases</prgn>. All MTA
8159 packages must come with a <prgn>newaliases</prgn> program,
8160 even if it does nothing, but older MTA packages did not do
8161 this so programs should not fail if <prgn>newaliases</prgn>
8162 cannot be found. Note that because of this, all MTA
8163 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8164 <tt>Replaces: mail-transport-agent</tt> control file
8169 The convention of writing <tt>forward to
8170 <var>address</var></tt> in the mailbox itself is not
8171 supported. Use a <tt>.forward</tt> file instead.</p>
8174 The <prgn>rmail</prgn> program used by UUCP
8175 for incoming mail should be <file>/usr/sbin/rmail</file>.
8176 Likewise, <prgn>rsmtp</prgn>, for receiving
8177 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8181 If your package needs to know what hostname to use on (for
8182 example) outgoing news and mail messages which are generated
8183 locally, you should use the file <file>/etc/mailname</file>. It
8184 will contain the portion after the username and <tt>@</tt>
8185 (at) sign for email addresses of users on the machine
8186 (followed by a newline).
8190 Such a package should check for the existence of this file
8191 when it is being configured. If it exists, it should be
8192 used without comment, although an MTA's configuration script
8193 may wish to prompt the user even if it finds that this file
8194 exists. If the file does not exist, the package should
8195 prompt the user for the value (preferably using
8196 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8197 as well as using it in the package's configuration. The
8198 prompt should make it clear that the name will not just be
8199 used by that package. For example, in this situation the
8200 <tt>inn</tt> package could say something like:
8201 <example compact="compact
">
8202 Please enter the "mail name
" of your system. This is the
8203 hostname portion of the address to be shown on outgoing
8204 news and mail messages. The default is
8205 <var>syshostname</var>, your system's host name. Mail
8206 name ["<var>syshostname
</var>"]:
8208 where <var>syshostname</var> is the output of <tt>hostname
8214 <heading>News system configuration</heading>
8217 All the configuration files related to the NNTP (news)
8218 servers and clients should be located under
8219 <file>/etc/news</file>.</p>
8222 There are some configuration issues that apply to a number
8223 of news clients and server packages on the machine. These
8227 <tag><file>/etc/news/organization</file></tag>
8229 A string which should appear as the
8230 organization header for all messages posted
8231 by NNTP clients on the machine
8234 <tag><file>/etc/news/server</file></tag>
8236 Contains the FQDN of the upstream NNTP
8237 server, or localhost if the local machine is
8242 Other global files may be added as required for cross-package news
8249 <heading>Programs for the X Window System</heading>
8252 <heading>Providing X support and package priorities</heading>
8255 Programs that can be configured with support for the X
8256 Window System must be configured to do so and must declare
8257 any package dependencies necessary to satisfy their
8258 runtime requirements when using the X Window System. If
8259 such a package is of higher priority than the X packages
8260 on which it depends, it is required that either the
8261 X-specific components be split into a separate package, or
8262 that an alternative version of the package, which includes
8263 X support, be provided, or that the package's priority be
8269 <heading>Packages providing an X server</heading>
8272 Packages that provide an X server that, directly or
8273 indirectly, communicates with real input and display
8274 hardware should declare in their control data that they
8275 provide the virtual package <tt>xserver</tt>.<footnote>
8276 This implements current practice, and provides an
8277 actual policy for usage of the <tt>xserver</tt>
8278 virtual package which appears in the virtual packages
8279 list. In a nutshell, X servers that interface
8280 directly with the display and input hardware or via
8281 another subsystem (e.g., GGI) should provide
8282 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8283 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8289 <heading>Packages providing a terminal emulator</heading>
8292 Packages that provide a terminal emulator for the X Window
8293 System which meet the criteria listed below should declare
8294 in their control data that they provide the virtual
8295 package <tt>x-terminal-emulator</tt>. They should also
8296 register themselves as an alternative for
8297 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8302 To be an <tt>x-terminal-emulator</tt>, a program must:
8303 <list compact="compact
">
8305 Be able to emulate a DEC VT100 terminal, or a
8306 compatible terminal.
8310 Support the command-line option <tt>-e
8311 <var>command</var></tt>, which creates a new
8312 terminal window<footnote>
8313 "New terminal window
" does not necessarily mean
8314 a new top-level X window directly parented by
8315 the window manager; it could, if the terminal
8316 emulator application were so coded, be a new
8317 "view
" in a multiple-document interface (MDI).
8319 and runs the specified <var>command</var>,
8320 interpreting the entirety of the rest of the command
8321 line as a command to pass straight to exec, in the
8322 manner that <tt>xterm</tt> does.
8326 Support the command-line option <tt>-T
8327 <var>title</var></tt>, which creates a new terminal
8328 window with the window title <var>title</var>.
8335 <heading>Packages providing a window manager</heading>
8338 Packages that provide a window manager should declare in
8339 their control data that they provide the virtual package
8340 <tt>x-window-manager</tt>. They should also register
8341 themselves as an alternative for
8342 <file>/usr/bin/x-window-manager</file>, with a priority
8343 calculated as follows:
8344 <list compact="compact
">
8346 Start with a priority of 20.
8350 If the window manager supports the Debian menu
8351 system, add 20 points if this support is available
8352 in the package's default configuration (i.e., no
8353 configuration files belonging to the system or user
8354 have to be edited to activate the feature); if
8355 configuration files must be modified, add only 10
8361 If the window manager complies with <url
8362 id="http://www.freedesktop.org/Standards/wm-spec
"
8363 name="The Window Manager Specification Project
">,
8364 written by the <url id="http://www.freedesktop.org/
"
8365 name="Free Desktop Group
">, add 40 points.
8369 If the window manager permits the X session to be
8370 restarted using a <em>different</em> window manager
8371 (without killing the X server) in its default
8372 configuration, add 10 points; otherwise add none.
8379 <heading>Packages providing fonts</heading>
8382 Packages that provide fonts for the X Window
8384 For the purposes of Debian Policy, a "font for the X
8385 Window System
" is one which is accessed via X protocol
8386 requests. Fonts for the Linux console, for PostScript
8387 renderer, or any other purpose, do not fit this
8388 definition. Any tool which makes such fonts available
8389 to the X Window System, however, must abide by this
8392 must do a number of things to ensure that they are both
8393 available without modification of the X or font server
8394 configuration, and that they do not corrupt files used by
8395 other font packages to register information about
8399 Fonts of any type supported by the X Window System
8400 must be in a separate binary package from any
8401 executables, libraries, or documentation (except
8402 that specific to the fonts shipped, such as their
8403 license information). If one or more of the fonts
8404 so packaged are necessary for proper operation of
8405 the package with which they are associated the font
8406 package may be Recommended; if the fonts merely
8407 provide an enhancement, a Suggests relationship may
8408 be used. Packages must not Depend on font
8410 This is because the X server may retrieve fonts
8411 from the local file system or over the network
8412 from an X font server; the Debian package system
8413 is empowered to deal only with the local
8419 BDF fonts must be converted to PCF fonts with the
8420 <prgn>bdftopcf</prgn> utility (available in the
8421 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8422 placed in a directory that corresponds to their
8424 <list compact="compact
">
8426 100 dpi fonts must be placed in
8427 <file>/usr/share/fonts/X11/100dpi/</file>.
8431 75 dpi fonts must be placed in
8432 <file>/usr/share/fonts/X11/75dpi/</file>.
8436 Character-cell fonts, cursor fonts, and other
8437 low-resolution fonts must be placed in
8438 <file>/usr/share/fonts/X11/misc/</file>.
8444 Type 1 fonts must be placed in
8445 <file>/usr/share/fonts/X11/Type1/</file>. If font
8446 metric files are available, they must be placed here
8451 Subdirectories of <file>/usr/share/fonts/X11/</file>
8452 other than those listed above must be neither
8453 created nor used. (The <file>PEX</file>, <file>CID</file>,
8454 <file>Speedo</file>, and <file>cyrillic</file> directories
8455 are excepted for historical reasons, but installation of
8456 files into these directories remains discouraged.)
8460 Font packages may, instead of placing files directly
8461 in the X font directories listed above, provide
8462 symbolic links in that font directory pointing to
8463 the files' actual location in the filesystem. Such
8464 a location must comply with the FHS.
8468 Font packages should not contain both 75dpi and
8469 100dpi versions of a font. If both are available,
8470 they should be provided in separate binary packages
8471 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8472 the names of the packages containing the
8473 corresponding fonts.
8477 Fonts destined for the <file>misc</file> subdirectory
8478 should not be included in the same package as 75dpi
8479 or 100dpi fonts; instead, they should be provided in
8480 a separate package with <tt>-misc</tt> appended to
8485 Font packages must not provide the files
8486 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8487 <file>fonts.scale</file> in a font directory:
8490 <file>fonts.dir</file> files must not be provided at all.
8494 <file>fonts.alias</file> and <file>fonts.scale</file>
8495 files, if needed, should be provided in the
8497 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8498 where <var>fontdir</var> is the name of the
8500 <file>/usr/share/fonts/X11/</file> where the
8501 package's corresponding fonts are stored
8502 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8503 <var>package</var> is the name of the package
8504 that provides these fonts, and
8505 <var>extension</var> is either <tt>scale</tt>
8506 or <tt>alias</tt>, whichever corresponds to
8513 Font packages must declare a dependency on
8514 <tt>xfonts-utils</tt> in their control
8519 Font packages that provide one or more
8520 <file>fonts.scale</file> files as described above must
8521 invoke <prgn>update-fonts-scale</prgn> on each
8522 directory into which they installed fonts
8523 <em>before</em> invoking
8524 <prgn>update-fonts-dir</prgn> on that directory.
8525 This invocation must occur in both the
8526 <prgn>postinst</prgn> (for all arguments) and
8527 <prgn>postrm</prgn> (for all arguments except
8528 <tt>upgrade</tt>) scripts.
8532 Font packages that provide one or more
8533 <file>fonts.alias</file> files as described above must
8534 invoke <prgn>update-fonts-alias</prgn> on each
8535 directory into which they installed fonts. This
8536 invocation must occur in both the
8537 <prgn>postinst</prgn> (for all arguments) and
8538 <prgn>postrm</prgn> (for all arguments except
8539 <tt>upgrade</tt>) scripts.
8543 Font packages must invoke
8544 <prgn>update-fonts-dir</prgn> on each directory into
8545 which they installed fonts. This invocation must
8546 occur in both the <prgn>postinst</prgn> (for all
8547 arguments) and <prgn>postrm</prgn> (for all
8548 arguments except <tt>upgrade</tt>) scripts.
8552 Font packages must not provide alias names for the
8553 fonts they include which collide with alias names
8554 already in use by fonts already packaged.
8558 Font packages must not provide fonts with the same
8559 XLFD registry name as another font already packaged.
8566 <heading>Application defaults files</heading>
8569 Application defaults files must be installed in the
8570 directory <file>/etc/X11/app-defaults/</file> (use of a
8571 localized subdirectory of <file>/etc/X11/</file> as described
8572 in the <em>X Toolkit Intrinsics - C Language
8573 Interface</em> manual is also permitted). They must be
8574 registered as <tt>conffile</tt>s or handled as
8575 configuration files.
8579 Customization of programs' X resources may also be
8580 supported with the provision of a file with the same name
8581 as that of the package placed in the
8582 <file>/etc/X11/Xresources/</file> directory, which must
8583 registered as a <tt>conffile</tt> or handled as a
8584 configuration file.<footnote>
8585 Note that this mechanism is not the same as using
8586 app-defaults; app-defaults are tied to the client
8587 binary on the local file system, whereas X resources
8588 are stored in the X server and affect all connecting
8595 <heading>Installation directory issues</heading>
8598 Packages using the X Window System should not be
8599 configured to install files under the
8600 <file>/usr/X11R6/</file> directory. The
8601 <file>/usr/X11R6/</file> directory hierarchy should be
8602 regarded as obsolete.
8606 Programs that use GNU <prgn>autoconf</prgn> and
8607 <prgn>automake</prgn> are usually easily configured at
8608 compile time to use <file>/usr/</file> instead of
8609 <file>/usr/X11R6/</file>, and this should be done whenever
8610 possible. Configuration files for window managers and
8611 display managers should be placed in a subdirectory of
8612 <file>/etc/X11/</file> corresponding to the package name due
8613 to these programs' tight integration with the mechanisms
8614 of the X Window System. Application-level programs should
8615 use the <file>/etc/</file> directory unless otherwise mandated
8620 The installation of files into subdirectories
8621 of <file>/usr/X11R6/include/X11/</file> and
8622 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8623 package maintainers should determine if subdirectories of
8624 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8629 Packages should install any relevant files into the
8630 directories <file>/usr/include/X11/</file> and
8631 <file>/usr/lib/X11/</file>, but if they do so, they must
8632 pre-depend on <tt>x11-common (>=
8633 1:7.0.0)</tt><footnote>
8635 These libraries used to be all symbolic
8636 links. However, with <tt>X11R7</tt>,
8637 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8638 are now real directories, and packages
8639 <strong>should</strong> ship their files here instead
8640 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8641 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8642 responsible for converting these symlinks into
8650 <heading>The OSF/Motif and OpenMotif libraries</heading>
8653 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8654 OpenMotif libraries</em><footnote>
8655 OSF/Motif and OpenMotif are collectively referred to as
8656 "Motif
" in this policy document.
8658 should be compiled against and tested with LessTif (a free
8659 re-implementation of Motif) instead. If the maintainer
8660 judges that the program or programs do not work
8661 sufficiently well with LessTif to be distributed and
8662 supported, but do so when compiled against Motif, then two
8663 versions of the package should be created; one linked
8664 statically against Motif and with <tt>-smotif</tt>
8665 appended to the package name, and one linked dynamically
8666 against Motif and with <tt>-dmotif</tt> appended to the
8671 Both Motif-linked versions are dependent
8672 upon non-DFSG-compliant software and thus cannot be
8673 uploaded to the <em>main</em> distribution; if the
8674 software is itself DFSG-compliant it may be uploaded to
8675 the <em>contrib</em> distribution. While known existing
8676 versions of Motif permit unlimited redistribution of
8677 binaries linked against the library (whether statically or
8678 dynamically), it is the package maintainer's
8679 responsibility to determine whether this is permitted by
8680 the license of the copy of Motif in their possession.
8686 <heading>Perl programs and modules</heading>
8689 Perl programs and modules should follow the current Perl policy.
8693 The Perl policy can be found in the <tt>perl-policy</tt>
8694 files in the <tt>debian-policy</tt> package.
8695 It is also available from the Debian web mirrors at
8696 <tt><url name="/doc/packaging-manuals/perl-policy/
"
8697 id="http://www.debian.org/doc/packaging-manuals/perl-policy/
"></tt>.
8702 <heading>Emacs lisp programs</heading>
8705 Please refer to the "Debian Emacs Policy
" for details of how to
8706 package emacs lisp programs.
8710 The Emacs policy is available in
8711 <file>debian-emacs-policy.gz</file> of the
8712 <package>emacsen-common</package> package.
8713 It is also available from the Debian web mirrors at
8714 <tt><url name="/doc/packaging-manuals/debian-emacs-policy
"
8715 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy
"></tt>.
8720 <heading>Games</heading>
8723 The permissions on <file>/var/games</file> are mode 755, owner
8724 <tt>root</tt> and group <tt>root</tt>.
8728 Each game decides on its own security policy.</p>
8731 Games which require protected, privileged access to
8732 high-score files, saved games, etc., may be made
8733 set-<em>group</em>-id (mode 2755) and owned by
8734 <tt>root:games</tt>, and use files and directories with
8735 appropriate permissions (770 <tt>root:games</tt>, for
8736 example). They must not be made
8737 set-<em>user</em>-id, as this causes security problems. (If
8738 an attacker can subvert any set-user-id game they can
8739 overwrite the executable of any other, causing other players
8740 of these games to run a Trojan horse program. With a
8741 set-group-id game the attacker only gets access to less
8742 important game data, and if they can get at the other
8743 players' accounts at all it will take considerably more
8747 Some packages, for example some fortune cookie programs, are
8748 configured by the upstream authors to install with their
8749 data files or other static information made unreadable so
8750 that they can only be accessed through set-id programs
8751 provided. You should not do this in a Debian package: anyone can
8752 download the <file>.deb</file> file and read the data from it,
8753 so there is no point making the files unreadable. Not
8754 making the files unreadable also means that you don't have
8755 to make so many programs set-id, which reduces the risk of a
8759 As described in the FHS, binaries of games should be
8760 installed in the directory <file>/usr/games</file>. This also
8761 applies to games that use the X Window System. Manual pages
8762 for games (X and non-X games) should be installed in
8763 <file>/usr/share/man/man6</file>.</p>
8769 <heading>Documentation</heading>
8772 <heading>Manual pages</heading>
8775 You should install manual pages in <prgn>nroff</prgn> source
8776 form, in appropriate places under <file>/usr/share/man</file>.
8777 You should only use sections 1 to 9 (see the FHS for more
8778 details). You must not install a pre-formatted "cat page
".
8782 Each program, utility, and function should have an
8783 associated manual page included in the same package. It is
8784 suggested that all configuration files also have a manual
8785 page included as well. Manual pages for protocols and other
8786 auxiliary things are optional.
8790 If no manual page is available, this is considered as a bug
8791 and should be reported to the Debian Bug Tracking System (the
8792 maintainer of the package is allowed to write this bug report
8793 themselves, if they so desire). Do not close the bug report
8794 until a proper man page is available.<footnote>
8795 It is not very hard to write a man page. See the
8796 <url id="http://www.schweikhardt.net/man_page_howto.html
"
8797 name="Man-Page-HOWTO
">,
8798 <manref name="man
" section="7">, the examples
8799 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8800 the helper programs <prgn>help2man</prgn>, or the
8801 directory <file>/usr/share/doc/man-db/examples</file>.
8806 You may forward a complaint about a missing man page to the
8807 upstream authors, and mark the bug as forwarded in the
8808 Debian bug tracking system. Even though the GNU Project do
8809 not in general consider the lack of a man page to be a bug,
8810 we do; if they tell you that they don't consider it a bug
8811 you should leave the bug in our bug tracking system open
8816 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8820 If one man page needs to be accessible via several names it
8821 is better to use a symbolic link than the <file>.so</file>
8822 feature, but there is no need to fiddle with the relevant
8823 parts of the upstream source to change from <file>.so</file> to
8824 symlinks: don't do it unless it's easy. You should not
8825 create hard links in the manual page directories, nor put
8826 absolute filenames in <file>.so</file> directives. The filename
8827 in a <file>.so</file> in a man page should be relative to the
8828 base of the man page tree (usually
8829 <file>/usr/share/man</file>). If you do not create any links
8830 (whether symlinks, hard links, or <tt>.so</tt> directives)
8831 in the file system to the alternate names of the man page,
8832 then you should not rely on <prgn>man</prgn> finding your
8833 man page under those names based solely on the information in
8834 the man page's header.<footnote>
8835 Supporting this in <prgn>man</prgn> often requires
8836 unreasonable processing time to find a manual page or to
8837 report that none exists, and moves knowledge into man's
8838 database that would be better left in the file system.
8839 This support is therefore deprecated and will cease to
8840 be present in the future.
8845 Manual pages in locale-specific subdirectories of
8846 <file>/usr/share/man</file> should use either UTF-8 or the usual
8847 legacy encoding for that language (normally the one corresponding
8848 to the shortest relevant locale name in
8849 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8850 <file>/usr/share/man/fr</file> should use either UTF-8 or
8851 ISO-8859-1.<footnote>
8852 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8853 use. In future, all manual pages will be required to use
8859 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8860 included in the subdirectory name unless it indicates a
8861 significant difference in the language, as this excludes
8862 speakers of the language in other countries.<footnote>
8863 At the time of writing, Chinese and Portuguese are the main
8864 languages with such differences, so <file>pt_BR</file>,
8865 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8870 Due to limitations in current implementations, all characters
8871 in the manual page source should be representable in the usual
8872 legacy encoding for that language, even if the file is
8873 actually encoded in UTF-8. Safe alternative ways to write many
8874 characters outside that range may be found in
8875 <manref name="groff_char
" section="7">.
8880 <heading>Info documents</heading>
8883 Info documents should be installed in <file>/usr/share/info</file>.
8884 They should be compressed with <tt>gzip -9</tt>.
8888 Your package should call <prgn>install-info</prgn> to update
8889 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8890 script when called with a <tt>configure</tt> argument, for
8892 <example compact="compact
">
8893 install-info --quiet --section Development Development \
8894 /usr/share/info/foobar.info
8898 It is a good idea to specify a section for the location of
8899 your program; this is done with the <tt>--section</tt>
8900 switch. To determine which section to use, you should look
8901 at <file>/usr/share/info/dir</file> on your system and choose the most
8902 relevant (or create a new section if none of the current
8903 sections are relevant). Note that the <tt>--section</tt>
8904 flag takes two arguments; the first is a regular expression
8905 to match (case-insensitively) against an existing section,
8906 the second is used when creating a new one.</p>
8909 You should remove the entries in the <prgn>prerm</prgn>
8910 script when called with a <tt>remove</tt> argument:
8911 <example compact="compact
">
8912 install-info --quiet --remove /usr/share/info/foobar.info
8916 If <prgn>install-info</prgn> cannot find a description entry
8917 in the Info file you must supply one. See <manref
8918 name="install-info
" section="8"> for details.</p>
8922 <heading>Additional documentation</heading>
8925 Any additional documentation that comes with the package may
8926 be installed at the discretion of the package maintainer.
8927 Plain text documentation should be installed in the directory
8928 <file>/usr/share/doc/<var>package</var></file>, where
8929 <var>package</var> is the name of the package, and
8930 compressed with <tt>gzip -9</tt> unless it is small.
8934 If a package comes with large amounts of documentation which
8935 many users of the package will not require you should create
8936 a separate binary package to contain it, so that it does not
8937 take up disk space on the machines of users who do not need
8938 or want it installed.</p>
8941 It is often a good idea to put text information files
8942 (<file>README</file>s, changelogs, and so forth) that come with
8943 the source package in <file>/usr/share/doc/<var>package</var></file>
8944 in the binary package. However, you don't need to install
8945 the instructions for building and installing the package, of
8949 Packages must not require the existence of any files in
8950 <file>/usr/share/doc/</file> in order to function
8952 The system administrator should be able to
8953 delete files in <file>/usr/share/doc/</file> without causing
8954 any programs to break.
8956 Any files that are referenced by programs but are also
8957 useful as stand alone documentation should be installed under
8958 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8959 <file>/usr/share/doc/<var>package</var></file>.
8963 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8964 link to another directory in <file>/usr/share/doc</file> only if
8965 the two packages both come from the same source and the
8966 first package Depends on the second.<footnote>
8968 Please note that this does not override the section on
8969 changelog files below, so the file
8970 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8971 must refer to the changelog for the current version of
8972 <var>package</var> in question. In practice, this means
8973 that the sources of the target and the destination of the
8974 symlink must be the same (same source package and
8981 Former Debian releases placed all additional documentation
8982 in <file>/usr/doc/<var>package</var></file>. This has been
8983 changed to <file>/usr/share/doc/<var>package</var></file>,
8984 and packages must not put documentation in the directory
8985 <file>/usr/doc/<var>package</var></file>. <footnote>
8986 At this phase of the transition, we no longer require a
8987 symbolic link in <file>/usr/doc/</file>. At a later point,
8988 policy shall change to make the symbolic links a bug.
8994 <heading>Preferred documentation formats</heading>
8997 The unification of Debian documentation is being carried out
9001 If your package comes with extensive documentation in a
9002 markup format that can be converted to various other formats
9003 you should if possible ship HTML versions in a binary
9004 package, in the directory
9005 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9006 its subdirectories.<footnote>
9007 The rationale: The important thing here is that HTML
9008 docs should be available in <em>some</em> package, not
9009 necessarily in the main binary package.
9014 Other formats such as PostScript may be provided at the
9015 package maintainer's discretion.
9019 <sect id="copyrightfile
">
9020 <heading>Copyright information</heading>
9023 Every package must be accompanied by a verbatim copy of its
9024 copyright and distribution license in the file
9025 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9026 file must neither be compressed nor be a symbolic link.
9030 In addition, the copyright file must say where the upstream
9031 sources (if any) were obtained. It should name the original
9032 authors of the package and the Debian maintainer(s) who were
9033 involved with its creation.
9037 Packages in the <em>contrib</em> or <em>non-free</em> archive
9038 areas should state in the copyright file that the package is not
9039 part of the Debian GNU/Linux distribution and briefly explain
9044 A copy of the file which will be installed in
9045 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9046 be in <file>debian/copyright</file> in the source package.
9050 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9051 link to another directory in <file>/usr/share/doc</file> only if
9052 the two packages both come from the same source and the
9053 first package Depends on the second. These rules are
9054 important because copyrights must be extractable by
9059 Packages distributed under the UCB BSD license, the Apache
9060 license (version 2.0), the Artistic license, the GNU GPL
9061 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9062 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9063 files under <file>/usr/share/common-licenses</file>,<footnote>
9066 <file>/usr/share/common-licenses/BSD</file>,
9067 <file>/usr/share/common-licenses/Apache-2.0</file>,
9068 <file>/usr/share/common-licenses/Artistic</file>,
9069 <file>/usr/share/common-licenses/GPL-2</file>,
9070 <file>/usr/share/common-licenses/GPL-3</file>,
9071 <file>/usr/share/common-licenses/LGPL-2</file>,
9072 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9073 <file>/usr/share/common-licenses/LGPL-3</file>,
9074 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9075 <file>/usr/share/common-licenses/GFDL-1.3</file>
9078 </footnote> rather than quoting them in the copyright
9083 You should not use the copyright file as a general <file>README</file>
9084 file. If your package has such a file it should be
9085 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9086 <file>README.Debian</file> or some other appropriate place.</p>
9090 <heading>Examples</heading>
9093 Any examples (configurations, source files, whatever),
9094 should be installed in a directory
9095 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9096 files should not be referenced by any program: they're there
9097 for the benefit of the system administrator and users as
9098 documentation only. Architecture-specific example files
9099 should be installed in a directory
9100 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9102 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9103 latter directory itself may be a symbolic link to the
9108 If the purpose of a package is to provide examples, then the
9109 example files may be installed into
9110 <file>/usr/share/doc/<var>package</var></file>.
9114 <sect id="changelogs
">
9115 <heading>Changelog files</heading>
9118 Packages that are not Debian-native must contain a
9119 compressed copy of the <file>debian/changelog</file> file from
9120 the Debian source tree in
9121 <file>/usr/share/doc/<var>package</var></file> with the name
9122 <file>changelog.Debian.gz</file>.
9126 If an upstream changelog is available, it should be accessible as
9127 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9128 plain text. If the upstream changelog is distributed in
9129 HTML, it should be made available in that form as
9130 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9131 and a plain text <file>changelog.gz</file> should be generated
9132 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9133 the upstream changelog files do not already conform to this
9134 naming convention, then this may be achieved either by
9135 renaming the files, or by adding a symbolic link, at the
9136 maintainer's discretion.<footnote>
9137 Rationale: People should not have to look in places for
9138 upstream changelogs merely because they are given
9139 different names or are distributed in HTML format.
9144 All of these files should be installed compressed using
9145 <tt>gzip -9</tt>, as they will become large with time even
9146 if they start out small.
9150 If the package has only one changelog which is used both as
9151 the Debian changelog and the upstream one because there is
9152 no separate upstream maintainer then that changelog should
9153 usually be installed as
9154 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9155 there is a separate upstream maintainer, but no upstream
9156 changelog, then the Debian changelog should still be called
9157 <file>changelog.Debian.gz</file>.
9161 For details about the format and contents of the Debian
9162 changelog file, please see <ref id="dpkgchangelog
">.
9167 <appendix id="pkg-scope
">
9168 <heading>Introduction and scope of these appendices</heading>
9171 These appendices are taken essentially verbatim from the
9172 now-deprecated Packaging Manual, version 3.2.1.0. They are
9173 the chapters which are likely to be of use to package
9174 maintainers and which have not already been included in the
9175 policy document itself. Most of these sections are very likely
9176 not relevant to policy; they should be treated as
9177 documentation for the packaging system. Please note that these
9178 appendices are included for convenience, and for historical
9179 reasons: they used to be part of policy package, and they have
9180 not yet been incorporated into dpkg documentation. However,
9181 they still have value, and hence they are presented here.
9185 They have not yet been checked to ensure that they are
9186 compatible with the contents of policy, and if there are any
9187 contradictions, the version in the main policy document takes
9188 precedence. The remaining chapters of the old Packaging
9189 Manual have also not been read in detail to ensure that there
9190 are not parts which have been left out. Both of these will be
9195 Certain parts of the Packaging manual were integrated into the
9196 Policy Manual proper, and removed from the appendices. Links
9197 have been placed from the old locations to the new ones.
9201 <prgn>dpkg</prgn> is a suite of programs for creating binary
9202 package files and installing and removing them on Unix
9204 <prgn>dpkg</prgn> is targeted primarily at Debian
9205 GNU/Linux, but may work on or be ported to other
9211 The binary packages are designed for the management of
9212 installed executable programs (usually compiled binaries) and
9213 their associated data, though source code examples and
9214 documentation are provided as part of some packages.</p>
9217 This manual describes the technical aspects of creating Debian
9218 binary packages (<file>.deb</file> files). It documents the
9219 behavior of the package management programs
9220 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9221 they interact with packages.</p>
9224 It also documents the interaction between
9225 <prgn>dselect</prgn>'s core and the access method scripts it
9226 uses to actually install the selected packages, and describes
9227 how to create a new access method.</p>
9230 This manual does not go into detail about the options and
9231 usage of the package building and installation tools. It
9232 should therefore be read in conjunction with those programs'
9237 The utility programs which are provided with <prgn>dpkg</prgn>
9238 for managing various system configuration and similar issues,
9239 such as <prgn>update-rc.d</prgn> and
9240 <prgn>install-info</prgn>, are not described in detail here -
9241 please see their man pages.
9245 It is assumed that the reader is reasonably familiar with the
9246 <prgn>dpkg</prgn> System Administrators' manual.
9247 Unfortunately this manual does not yet exist.
9251 The Debian version of the FSF's GNU hello program is provided
9252 as an example for people wishing to create Debian
9253 packages. The Debian <prgn>debmake</prgn> package is
9254 recommended as a very helpful tool in creating and maintaining
9255 Debian packages. However, while the tools and examples are
9256 helpful, they do not replace the need to read and follow the
9257 Policy and Programmer's Manual.</p>
9260 <appendix id="pkg-binarypkg
">
9261 <heading>Binary packages (from old Packaging Manual)</heading>
9264 The binary package has two main sections. The first part
9265 consists of various control information files and scripts used
9266 by <prgn>dpkg</prgn> when installing and removing. See <ref
9267 id="pkg-controlarea
">.
9271 The second part is an archive containing the files and
9272 directories to be installed.
9276 In the future binary packages may also contain other
9277 components, such as checksums and digital signatures. The
9278 format for the archive is described in full in the
9279 <file>deb(5)</file> man page.
9283 <sect id="pkg-bincreating
"><heading>Creating package files -
9284 <prgn>dpkg-deb</prgn>
9288 All manipulation of binary package files is done by
9289 <prgn>dpkg-deb</prgn>; it's the only program that has
9290 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9291 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9292 will spot that the options requested are appropriate to
9293 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9298 In order to create a binary package you must make a
9299 directory tree which contains all the files and directories
9300 you want to have in the file system data part of the package.
9301 In Debian-format source packages this directory is usually
9302 <file>debian/tmp</file>, relative to the top of the package's
9307 They should have the locations (relative to the root of the
9308 directory tree you're constructing) ownerships and
9309 permissions which you want them to have on the system when
9314 With current versions of <prgn>dpkg</prgn> the uid/username
9315 and gid/groupname mappings for the users and groups being
9316 used should be the same on the system where the package is
9317 built and the one where it is installed.
9321 You need to add one special directory to the root of the
9322 miniature file system tree you're creating:
9323 <prgn>DEBIAN</prgn>. It should contain the control
9324 information files, notably the binary package control file
9325 (see <ref id="pkg-controlfile
">).
9329 The <prgn>DEBIAN</prgn> directory will not appear in the
9330 file system archive of the package, and so won't be installed
9331 by <prgn>dpkg</prgn> when the package is installed.
9335 When you've prepared the package, you should invoke:
9337 dpkg --build <var>directory</var>
9342 This will build the package in
9343 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9344 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9345 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9350 See the man page <manref name="dpkg-deb
" section="8"> for details of how
9351 to examine the contents of this newly-created file. You may find the
9352 output of following commands enlightening:
9354 dpkg-deb --info <var>filename</var>.deb
9355 dpkg-deb --contents <var>filename</var>.deb
9356 dpkg --contents <var>filename</var>.deb
9358 To view the copyright file for a package you could use this command:
9360 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9365 <sect id="pkg-controlarea
">
9366 <heading>Package control information files</heading>
9369 The control information portion of a binary package is a
9370 collection of files with names known to <prgn>dpkg</prgn>.
9371 It will treat the contents of these files specially - some
9372 of them contain information used by <prgn>dpkg</prgn> when
9373 installing or removing the package; others are scripts which
9374 the package maintainer wants <prgn>dpkg</prgn> to run.
9378 It is possible to put other files in the package control
9379 area, but this is not generally a good idea (though they
9380 will largely be ignored).
9384 Here is a brief list of the control info files supported by
9385 <prgn>dpkg</prgn> and a summary of what they're used for.
9390 <tag><tt>control</tt>
9393 This is the key description file used by
9394 <prgn>dpkg</prgn>. It specifies the package's name
9395 and version, gives its description for the user,
9396 states its relationships with other packages, and so
9397 forth. See <ref id="sourcecontrolfiles
"> and
9398 <ref id="binarycontrolfiles
">.
9402 It is usually generated automatically from information
9403 in the source package by the
9404 <prgn>dpkg-gencontrol</prgn> program, and with
9405 assistance from <prgn>dpkg-shlibdeps</prgn>.
9406 See <ref id="pkg-sourcetools
">.
9410 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9415 These are executable files (usually scripts) which
9416 <prgn>dpkg</prgn> runs during installation, upgrade
9417 and removal of packages. They allow the package to
9418 deal with matters which are particular to that package
9419 or require more complicated processing than that
9420 provided by <prgn>dpkg</prgn>. Details of when and
9421 how they are called are in <ref id="maintainerscripts
">.
9425 It is very important to make these scripts idempotent.
9426 See <ref id="idempotency
">.
9430 The maintainer scripts are guaranteed to run with a
9431 controlling terminal and can interact with the user.
9432 See <ref id="controllingterminal
">.
9436 <tag><tt>conffiles</tt>
9439 This file contains a list of configuration files which
9440 are to be handled automatically by <prgn>dpkg</prgn>
9441 (see <ref id="pkg-conffiles
">). Note that not necessarily
9442 every configuration file should be listed here.
9445 <tag><tt>shlibs</tt>
9448 This file contains a list of the shared libraries
9449 supplied by the package, with dependency details for
9450 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9451 when it determines what dependencies are required in a
9452 package control file. The <tt>shlibs</tt> file format
9453 is described on <ref id="shlibs
">.
9458 <sect id="pkg-controlfile
">
9459 <heading>The main control information file: <tt>control</tt></heading>
9462 The most important control information file used by
9463 <prgn>dpkg</prgn> when it installs a package is
9464 <tt>control</tt>. It contains all the package's "vital
9469 The binary package control files of packages built from
9470 Debian sources are made by a special tool,
9471 <prgn>dpkg-gencontrol</prgn>, which reads
9472 <file>debian/control</file> and <file>debian/changelog</file> to
9473 find the information it needs. See <ref id="pkg-sourcepkg
"> for
9478 The fields in binary package control files are listed in
9479 <ref id="binarycontrolfiles
">.
9483 A description of the syntax of control files and the purpose
9484 of the fields is available in <ref id="controlfields
">.
9489 <heading>Time Stamps</heading>
9492 See <ref id="timestamps
">.
9497 <appendix id="pkg-sourcepkg
">
9498 <heading>Source packages (from old Packaging Manual) </heading>
9501 The Debian binary packages in the distribution are generated
9502 from Debian sources, which are in a special format to assist
9503 the easy and automatic building of binaries.
9506 <sect id="pkg-sourcetools
">
9507 <heading>Tools for processing source packages</heading>
9510 Various tools are provided for manipulating source packages;
9511 they pack and unpack sources and help build of binary
9512 packages and help manage the distribution of new versions.
9516 They are introduced and typical uses described here; see
9517 <manref name="dpkg-source
" section="1"> for full
9518 documentation about their arguments and operation.
9522 For examples of how to construct a Debian source package,
9523 and how to use those utilities that are used by Debian
9524 source packages, please see the <prgn>hello</prgn> example
9528 <sect1 id="pkg-dpkg-source
">
9530 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9535 This program is frequently used by hand, and is also
9536 called from package-independent automated building scripts
9537 such as <prgn>dpkg-buildpackage</prgn>.
9541 To unpack a package it is typically invoked with
9543 dpkg-source -x <var>.../path/to/filename</var>.dsc
9548 with the <file><var>filename</var>.tar.gz</file> and
9549 <file><var>filename</var>.diff.gz</file> (if applicable) in
9550 the same directory. It unpacks into
9551 <file><var>package</var>-<var>version</var></file>, and if
9553 <file><var>package</var>-<var>version</var>.orig</file>, in
9554 the current directory.
9558 To create a packed source archive it is typically invoked:
9560 dpkg-source -b <var>package</var>-<var>version</var>
9565 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9566 <file>.diff.gz</file> (if appropriate) in the current
9567 directory. <prgn>dpkg-source</prgn> does not clean the
9568 source tree first - this must be done separately if it is
9573 See also <ref id="pkg-sourcearchives
">.</p>
9577 <sect1 id="pkg-dpkg-buildpackage
">
9579 <prgn>dpkg-buildpackage</prgn> - overall package-building
9584 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9585 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9586 targets <tt>clean</tt>, <tt>build</tt> and
9587 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9588 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9589 source and binary package upload.
9593 It is usually invoked by hand from the top level of the
9594 built or unbuilt source directory. It may be invoked with
9595 no arguments; useful arguments include:
9596 <taglist compact="compact
">
9597 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9600 Do not sign the <tt>.changes</tt> file or the
9601 source package <tt>.dsc</tt> file, respectively.</p>
9603 <tag><tt>-p<var>sign-command</var></tt></tag>
9606 Invoke <var>sign-command</var> instead of finding
9607 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9608 <var>sign-command</var> must behave just like
9609 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9611 <tag><tt>-r<var>root-command</var></tt></tag>
9614 When root privilege is required, invoke the command
9615 <var>root-command</var>. <var>root-command</var>
9616 should invoke its first argument as a command, from
9617 the <prgn>PATH</prgn> if necessary, and pass its
9618 second and subsequent arguments to the command it
9619 calls. If no <var>root-command</var> is supplied
9620 then <var>dpkg-buildpackage</var> will take no
9621 special action to gain root privilege, so that for
9622 most packages it will have to be invoked as root to
9625 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9628 Two types of binary-only build and upload - see
9629 <manref name="dpkg-source
" section="1">.
9636 <sect1 id="pkg-dpkg-gencontrol
">
9638 <prgn>dpkg-gencontrol</prgn> - generates binary package
9643 This program is usually called from <file>debian/rules</file>
9644 (see <ref id="pkg-sourcetree
">) in the top level of the source
9649 This is usually done just before the files and directories in the
9650 temporary directory tree where the package is being built have their
9651 permissions and ownerships set and the package is constructed using
9652 <prgn>dpkg-deb/</prgn>
9654 This is so that the control file which is produced has
9655 the right permissions
9660 <prgn>dpkg-gencontrol</prgn> must be called after all the
9661 files which are to go into the package have been placed in
9662 the temporary build directory, so that its calculation of
9663 the installed size of a package is correct.
9667 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9668 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9669 variable substitutions created by
9670 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9675 For a package which generates only one binary package, and
9676 which builds it in <file>debian/tmp</file> relative to the top
9677 of the source package, it is usually sufficient to call
9678 <prgn>dpkg-gencontrol</prgn>.
9682 Sources which build several binaries will typically need
9685 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9686 </example> The <tt>-P</tt> tells
9687 <prgn>dpkg-gencontrol</prgn> that the package is being
9688 built in a non-default directory, and the <tt>-p</tt>
9689 tells it which package's control file should be generated.
9693 <prgn>dpkg-gencontrol</prgn> also adds information to the
9694 list of files in <file>debian/files</file>, for the benefit of
9695 (for example) a future invocation of
9696 <prgn>dpkg-genchanges</prgn>.</p>
9699 <sect1 id="pkg-dpkg-shlibdeps
">
9701 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9706 This program is usually called from <file>debian/rules</file>
9707 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9708 id="pkg-sourcetree
">), in the top level of the source tree.
9712 Its arguments are executables and shared libraries
9715 They may be specified either in the locations in the
9716 source tree where they are created or in the locations
9717 in the temporary build tree where they are installed
9718 prior to binary package creation.
9720 </footnote> for which shared library dependencies should
9721 be included in the binary package's control file.
9725 If some of the found shared libraries should only
9726 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9727 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9728 by using the <tt>-d<var>dependency-field</var></tt> option
9729 before those executable(s). (Each <tt>-d</tt> option
9730 takes effect until the next <tt>-d</tt>.)
9734 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9735 output control file to be modified. Instead by default it
9736 adds to the <file>debian/substvars</file> file variable
9737 settings like <tt>shlibs:Depends</tt>. These variable
9738 settings must be referenced in dependency fields in the
9739 appropriate per-binary-package sections of the source
9744 For example, a package that generates an essential part
9745 which requires dependencies, and optional parts that
9746 which only require a recommendation, would separate those
9747 two sets of dependencies into two different fields.<footnote>
9748 At the time of writing, an example for this was the
9749 <package/xmms/ package, with Depends used for the xmms
9750 executable, Recommends for the plug-ins and Suggests for
9751 even more optional features provided by unzip.
9753 It can say in its <file>debian/rules</file>:
9755 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9756 -dRecommends <var>optionalpart anotheroptionalpart</var>
9758 and then in its main control file <file>debian/control</file>:
9761 Depends: ${shlibs:Depends}
9762 Recommends: ${shlibs:Recommends}
9768 Sources which produce several binary packages with
9769 different shared library dependency requirements can use
9770 the <tt>-p<var>varnameprefix</var></tt> option to override
9771 the default <tt>shlibs:</tt> prefix (one invocation of
9772 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9773 They can thus produce several sets of dependency
9774 variables, each of the form
9775 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9776 which can be referred to in the appropriate parts of the
9777 binary package control files.
9782 <sect1 id="pkg-dpkg-distaddfile
">
9784 <prgn>dpkg-distaddfile</prgn> - adds a file to
9785 <file>debian/files</file>
9789 Some packages' uploads need to include files other than
9790 the source and binary package files.
9794 <prgn>dpkg-distaddfile</prgn> adds a file to the
9795 <file>debian/files</file> file so that it will be included in
9796 the <file>.changes</file> file when
9797 <prgn>dpkg-genchanges</prgn> is run.
9801 It is usually invoked from the <tt>binary</tt> target of
9802 <file>debian/rules</file>:
9804 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9806 The <var>filename</var> is relative to the directory where
9807 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9808 is usually the directory above the top level of the source
9809 tree. The <file>debian/rules</file> target should put the
9810 file there just before or just after calling
9811 <prgn>dpkg-distaddfile</prgn>.
9815 The <var>section</var> and <var>priority</var> are passed
9816 unchanged into the resulting <file>.changes</file> file.
9821 <sect1 id="pkg-dpkg-genchanges
">
9823 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9828 This program is usually called by package-independent
9829 automatic building scripts such as
9830 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9835 It is usually called in the top level of a built source
9836 tree, and when invoked with no arguments will print out a
9837 straightforward <file>.changes</file> file based on the
9838 information in the source package's changelog and control
9839 file and the binary and source packages which should have
9845 <sect1 id="pkg-dpkg-parsechangelog
">
9847 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9848 representation of a changelog
9852 This program is used internally by
9853 <prgn>dpkg-source</prgn> et al. It may also occasionally
9854 be useful in <file>debian/rules</file> and elsewhere. It
9855 parses a changelog, <file>debian/changelog</file> by default,
9856 and prints a control-file format representation of the
9857 information in it to standard output.
9861 <sect1 id="pkg-dpkg-architecture
">
9863 <prgn>dpkg-architecture</prgn> - information about the build and
9868 This program can be used manually, but is also invoked by
9869 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9870 environment or make variables which specify the build and host
9871 architecture for the package building process.
9876 <sect id="pkg-sourcetree
">
9877 <heading>The Debianised source tree</heading>
9880 The source archive scheme described later is intended to
9881 allow a Debianised source tree with some associated control
9882 information to be reproduced and transported easily. The
9883 Debianised source tree is a version of the original program
9884 with certain files added for the benefit of the
9885 Debianisation process, and with any other changes required
9886 made to the rest of the source code and installation
9891 The extra files created for Debian are in the subdirectory
9892 <file>debian</file> of the top level of the Debianised source
9893 tree. They are described below.
9896 <sect1 id="pkg-debianrules
">
9897 <heading><file>debian/rules</file> - the main building script</heading>
9900 See <ref id="debianrules
">.
9905 <sect1 id="pkg-dpkgchangelog
">
9906 <heading><file>debian/changelog</file></heading>
9909 See <ref id="dpkgchangelog
">.
9912 <sect2><heading>Defining alternative changelog formats
9916 It is possible to use a different format to the standard
9917 one, by providing a parser for the format you wish to
9922 In order to have <tt>dpkg-parsechangelog</tt> run your
9923 parser, you must include a line within the last 40 lines
9924 of your file matching the Perl regular expression:
9925 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9926 parentheses should be the name of the format. For
9927 example, you might say:
9929 @@@ changelog-format: joebloggs @@@
9931 Changelog format names are non-empty strings of alphanumerics.
9935 If such a line exists then <tt>dpkg-parsechangelog</tt>
9936 will look for the parser as
9937 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9939 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9940 it is an error for it not to find it, or for it not to
9941 be an executable program. The default changelog format
9942 is <tt>dpkg</tt>, and a parser for it is provided with
9943 the <tt>dpkg</tt> package.
9947 The parser will be invoked with the changelog open on
9948 standard input at the start of the file. It should read
9949 the file (it may seek if it wishes) to determine the
9950 information required and return the parsed information
9951 to standard output in the form of a series of control
9952 fields in the standard format. By default it should
9953 return information about only the most recent version in
9954 the changelog; it should accept a
9955 <tt>-v<var>version</var></tt> option to return changes
9956 information from all versions present <em>strictly
9957 after</em> <var>version</var>, and it should then be an
9958 error for <var>version</var> not to be present in the
9964 <list compact="compact
">
9965 <item><qref id="f-Source
"><tt>Source</tt></qref></item>
9966 <item><qref id="f-Version
"><tt>Version</tt></qref> (mandatory)</item>
9967 <item><qref id="f-Distribution
"><tt>Distribution</tt></qref> (mandatory)</item>
9968 <item><qref id="f-Urgency
"><tt>Urgency</tt></qref> (mandatory)</item>
9969 <item><qref id="f-Maintainer
"><tt>Maintainer</tt></qref> (mandatory)</item>
9970 <item><qref id="f-Date
"><tt>Date</tt></qref></item>
9971 <item><qref id="f-Changes
"><tt>Changes</tt></qref> (mandatory)</item>
9976 If several versions are being returned (due to the use
9977 of <tt>-v</tt>), the urgency value should be of the
9978 highest urgency code listed at the start of any of the
9979 versions requested followed by the concatenated
9980 (space-separated) comments from all the versions
9981 requested; the maintainer, version, distribution and
9982 date should always be from the most recent version.
9986 For the format of the <tt>Changes</tt> field see
9987 <ref id="f-Changes
">.
9991 If the changelog format which is being parsed always or
9992 almost always leaves a blank line between individual
9993 change notes these blank lines should be stripped out,
9994 so as to make the resulting output compact.
9998 If the changelog format does not contain date or package
9999 name information this information should be omitted from
10000 the output. The parser should not attempt to synthesize
10001 it or find it from other sources.
10005 If the changelog does not have the expected format the
10006 parser should exit with a nonzero exit status, rather
10007 than trying to muddle through and possibly generating
10012 A changelog parser may not interact with the user at
10018 <sect1 id="pkg-srcsubstvars
">
10019 <heading><file>debian/substvars</file> and variable substitutions</heading>
10022 See <ref id="substvars
">.
10028 <heading><file>debian/files</file></heading>
10031 See <ref id="debianfiles
">.
10035 <sect1><heading><file>debian/tmp</file>
10039 This is the canonical temporary location for the
10040 construction of binary packages by the <tt>binary</tt>
10041 target. The directory <file>tmp</file> serves as the root of
10042 the file system tree as it is being constructed (for
10043 example, by using the package's upstream makefiles install
10044 targets and redirecting the output there), and it also
10045 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10046 id="pkg-bincreating
">.
10050 If several binary packages are generated from the same
10051 source tree it is usual to use several
10052 <file>debian/tmp<var>something</var></file> directories, for
10053 example <file>tmp-a</file> or <file>tmp-doc</file>.
10057 Whatever <file>tmp</file> directories are created and used by
10058 <tt>binary</tt> must of course be removed by the
10059 <tt>clean</tt> target.</p></sect1>
10063 <sect id="pkg-sourcearchives
"><heading>Source packages as archives
10067 As it exists on the FTP site, a Debian source package
10068 consists of three related files. You must have the right
10069 versions of all three to be able to use them.
10074 <tag>Debian source control file - <tt>.dsc</tt></tag>
10076 This file is a control file used by <prgn>dpkg-source</prgn>
10077 to extract a source package.
10078 See <ref id="debiansourcecontrolfiles
">.
10082 Original source archive -
10084 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10090 This is a compressed (with <tt>gzip -9</tt>)
10091 <prgn>tar</prgn> file containing the source code from
10092 the upstream authors of the program.
10097 Debianisation diff -
10099 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10105 This is a unified context diff (<tt>diff -u</tt>)
10106 giving the changes which are required to turn the
10107 original source into the Debian source. These changes
10108 may only include editing and creating plain files.
10109 The permissions of files, the targets of symbolic
10110 links and the characteristics of special files or
10111 pipes may not be changed and no files may be removed
10116 All the directories in the diff must exist, except the
10117 <file>debian</file> subdirectory of the top of the source
10118 tree, which will be created by
10119 <prgn>dpkg-source</prgn> if necessary when unpacking.
10123 The <prgn>dpkg-source</prgn> program will
10124 automatically make the <file>debian/rules</file> file
10125 executable (see below).</p></item>
10130 If there is no original source code - for example, if the
10131 package is specially prepared for Debian or the Debian
10132 maintainer is the same as the upstream maintainer - the
10133 format is slightly different: then there is no diff, and the
10135 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10136 and preferably contains a directory named
10137 <file><var>package</var>-<var>version</var></file>.
10142 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10145 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10146 Debian source package. However, if it is not available it
10147 is possible to unpack a Debian source archive as follows:
10148 <enumlist compact="compact
">
10151 Untar the tarfile, which will create a <file>.orig</file>
10155 <p>Rename the <file>.orig</file> directory to
10156 <file><var>package</var>-<var>version</var></file>.</p>
10160 Create the subdirectory <file>debian</file> at the top of
10161 the source tree.</p>
10163 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10165 <item><p>Untar the tarfile again if you want a copy of the original
10166 source code alongside the Debianised version.</p>
10171 It is not possible to generate a valid Debian source archive
10172 without using <prgn>dpkg-source</prgn>. In particular,
10173 attempting to use <prgn>diff</prgn> directly to generate the
10174 <file>.diff.gz</file> file will not work.
10178 <heading>Restrictions on objects in source packages</heading>
10181 The source package may not contain any hard links
10183 This is not currently detected when building source
10184 packages, but only when extracting
10188 Hard links may be permitted at some point in the
10189 future, but would require a fair amount of
10191 </footnote>, device special files, sockets or setuid or
10194 Setgid directories are allowed.
10199 The source packaging tools manage the changes between the
10200 original and Debianised source using <prgn>diff</prgn> and
10201 <prgn>patch</prgn>. Turning the original source tree as
10202 included in the <file>.orig.tar.gz</file> into the debianised
10203 source must not involve any changes which cannot be
10204 handled by these tools. Problematic changes which cause
10205 <prgn>dpkg-source</prgn> to halt with an error when
10206 building the source package are:
10207 <list compact="compact
">
10208 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10210 <item><p>Changing the targets of symbolic links.</p>
10212 <item><p>Creating directories, other than <file>debian</file>.</p>
10214 <item><p>Changes to the contents of binary files.</p></item>
10215 </list> Changes which cause <prgn>dpkg-source</prgn> to
10216 print a warning but continue anyway are:
10217 <list compact="compact
">
10220 Removing files, directories or symlinks.
10222 Renaming a file is not treated specially - it is
10223 seen as the removal of the old file (which
10224 generates a warning, but is otherwise ignored),
10225 and the creation of the new one.
10231 Changed text files which are missing the usual final
10232 newline (either in the original or the modified
10237 Changes which are not represented, but which are not detected by
10238 <prgn>dpkg-source</prgn>, are:
10239 <list compact="compact
">
10240 <item><p>Changing the permissions of files (other than
10241 <file>debian/rules</file>) and directories.</p></item>
10246 The <file>debian</file> directory and <file>debian/rules</file>
10247 are handled specially by <prgn>dpkg-source</prgn> - before
10248 applying the changes it will create the <file>debian</file>
10249 directory, and afterwards it will make
10250 <file>debian/rules</file> world-executable.
10256 <appendix id="pkg-controlfields
">
10257 <heading>Control files and their fields (from old Packaging Manual)</heading>
10260 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10261 data in a common format, known as control files. Binary and
10262 source packages have control data as do the <file>.changes</file>
10263 files which control the installation of uploaded files, and
10264 <prgn>dpkg</prgn>'s internal databases are in a similar
10269 <heading>Syntax of control files</heading>
10272 See <ref id="controlsyntax
">.
10276 It is important to note that there are several fields which
10277 are optional as far as <prgn>dpkg</prgn> and the related
10278 tools are concerned, but which must appear in every Debian
10279 package, or whose omission may cause problems.
10284 <heading>List of fields</heading>
10287 See <ref id="controlfieldslist
">.
10291 This section now contains only the fields that didn't belong
10292 to the Policy manual.
10295 <sect1 id="pkg-f-Filename
">
10296 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10299 These fields in <tt>Packages</tt> files give the
10300 filename(s) of (the parts of) a package in the
10301 distribution directories, relative to the root of the
10302 Debian hierarchy. If the package has been split into
10303 several parts the parts are all listed in order, separated
10308 <sect1 id="pkg-f-Size
">
10309 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10312 These fields in <file>Packages</file> files give the size (in
10313 bytes, expressed in decimal) and MD5 checksum of the
10314 file(s) which make(s) up a binary package in the
10315 distribution. If the package is split into several parts
10316 the values for the parts are listed in order, separated by
10321 <sect1 id="pkg-f-Status
">
10322 <heading><tt>Status</tt></heading>
10325 This field in <prgn>dpkg</prgn>'s status file records
10326 whether the user wants a package installed, removed or
10327 left alone, whether it is broken (requiring
10328 re-installation) or not and what its current state on the
10329 system is. Each of these pieces of information is a
10334 <sect1 id="pkg-f-Config-Version
">
10335 <heading><tt>Config-Version</tt></heading>
10338 If a package is not installed or not configured, this
10339 field in <prgn>dpkg</prgn>'s status file records the last
10340 version of the package which was successfully
10345 <sect1 id="pkg-f-Conffiles
">
10346 <heading><tt>Conffiles</tt></heading>
10349 This field in <prgn>dpkg</prgn>'s status file contains
10350 information about the automatically-managed configuration
10351 files held by a package. This field should <em>not</em>
10352 appear anywhere in a package!
10357 <heading>Obsolete fields</heading>
10360 These are still recognized by <prgn>dpkg</prgn> but should
10361 not appear anywhere any more.
10363 <taglist compact="compact
">
10365 <tag><tt>Revision</tt></tag>
10366 <tag><tt>Package-Revision</tt></tag>
10367 <tag><tt>Package_Revision</tt></tag>
10369 The Debian revision part of the package version was
10370 at one point in a separate control file field. This
10371 field went through several names.
10374 <tag><tt>Recommended</tt></tag>
10375 <item>Old name for <tt>Recommends</tt>.</item>
10377 <tag><tt>Optional</tt></tag>
10378 <item>Old name for <tt>Suggests</tt>.</item>
10380 <tag><tt>Class</tt></tag>
10381 <item>Old name for <tt>Priority</tt>.</item>
10390 <appendix id="pkg-conffiles
">
10391 <heading>Configuration file handling (from old Packaging Manual)</heading>
10394 <prgn>dpkg</prgn> can do a certain amount of automatic
10395 handling of package configuration files.
10399 Whether this mechanism is appropriate depends on a number of
10400 factors, but basically there are two approaches to any
10401 particular configuration file.
10405 The easy method is to ship a best-effort configuration in the
10406 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10407 handle updates. If the user is unlikely to want to edit the
10408 file, but you need them to be able to without losing their
10409 changes, and a new package with a changed version of the file
10410 is only released infrequently, this is a good approach.
10414 The hard method is to build the configuration file from
10415 scratch in the <prgn>postinst</prgn> script, and to take the
10416 responsibility for fixing any mistakes made in earlier
10417 versions of the package automatically. This will be
10418 appropriate if the file is likely to need to be different on
10422 <sect><heading>Automatic handling of configuration files by
10427 A package may contain a control area file called
10428 <tt>conffiles</tt>. This file should be a list of filenames
10429 of configuration files needing automatic handling, separated
10430 by newlines. The filenames should be absolute pathnames,
10431 and the files referred to should actually exist in the
10436 When a package is upgraded <prgn>dpkg</prgn> will process
10437 the configuration files during the configuration stage,
10438 shortly before it runs the package's <prgn>postinst</prgn>
10443 For each file it checks to see whether the version of the
10444 file included in the package is the same as the one that was
10445 included in the last version of the package (the one that is
10446 being upgraded from); it also compares the version currently
10447 installed on the system with the one shipped with the last
10452 If neither the user nor the package maintainer has changed
10453 the file, it is left alone. If one or the other has changed
10454 their version, then the changed version is preferred - i.e.,
10455 if the user edits their file, but the package maintainer
10456 doesn't ship a different version, the user's changes will
10457 stay, silently, but if the maintainer ships a new version
10458 and the user hasn't edited it the new version will be
10459 installed (with an informative message). If both have
10460 changed their version the user is prompted about the problem
10461 and must resolve the differences themselves.
10465 The comparisons are done by calculating the MD5 message
10466 digests of the files, and storing the MD5 of the file as it
10467 was included in the most recent version of the package.
10471 When a package is installed for the first time
10472 <prgn>dpkg</prgn> will install the file that comes with it,
10473 unless that would mean overwriting a file already on the
10478 However, note that <prgn>dpkg</prgn> will <em>not</em>
10479 replace a conffile that was removed by the user (or by a
10480 script). This is necessary because with some programs a
10481 missing file produces an effect hard or impossible to
10482 achieve in another way, so that a missing file needs to be
10483 kept that way if the user did it.
10487 Note that a package should <em>not</em> modify a
10488 <prgn>dpkg</prgn>-handled conffile in its maintainer
10489 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10490 the user confusing and possibly dangerous options for
10491 conffile update when the package is upgraded.</p>
10494 <sect><heading>Fully-featured maintainer script configuration
10499 For files which contain site-specific information such as
10500 the hostname and networking details and so forth, it is
10501 better to create the file in the package's
10502 <prgn>postinst</prgn> script.
10506 This will typically involve examining the state of the rest
10507 of the system to determine values and other information, and
10508 may involve prompting the user for some information which
10509 can't be obtained some other way.
10513 When using this method there are a couple of important
10514 issues which should be considered:
10518 If you discover a bug in the program which generates the
10519 configuration file, or if the format of the file changes
10520 from one version to the next, you will have to arrange for
10521 the postinst script to do something sensible - usually this
10522 will mean editing the installed configuration file to remove
10523 the problem or change the syntax. You will have to do this
10524 very carefully, since the user may have changed the file,
10525 perhaps to fix the very problem that your script is trying
10526 to deal with - you will have to detect these situations and
10527 deal with them correctly.
10531 If you do go down this route it's probably a good idea to
10532 make the program that generates the configuration file(s) a
10533 separate program in <file>/usr/sbin</file>, by convention called
10534 <file><var>package</var>config</file> and then run that if
10535 appropriate from the post-installation script. The
10536 <tt><var>package</var>config</tt> program should not
10537 unquestioningly overwrite an existing configuration - if its
10538 mode of operation is geared towards setting up a package for
10539 the first time (rather than any arbitrary reconfiguration
10540 later) you should have it check whether the configuration
10541 already exists, and require a <tt>--force</tt> flag to
10542 overwrite it.</p></sect>
10545 <appendix id="pkg-alternatives
"><heading>Alternative versions of
10546 an interface - <prgn>update-alternatives</prgn> (from old
10551 When several packages all provide different versions of the
10552 same program or file it is useful to have the system select a
10553 default, but to allow the system administrator to change it
10554 and have their decisions respected.
10558 For example, there are several versions of the <prgn>vi</prgn>
10559 editor, and there is no reason to prevent all of them from
10560 being installed at once, each under their own name
10561 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10562 Nevertheless it is desirable to have the name <tt>vi</tt>
10563 refer to something, at least by default.
10567 If all the packages involved cooperate, this can be done with
10568 <prgn>update-alternatives</prgn>.
10572 Each package provides its own version under its own name, and
10573 calls <prgn>update-alternatives</prgn> in its postinst to
10574 register its version (and again in its prerm to deregister
10579 See the man page <manref name="update-alternatives
"
10580 section="8"> for details.
10584 If <prgn>update-alternatives</prgn> does not seem appropriate
10585 you may wish to consider using diversions instead.</p>
10588 <appendix id="pkg-diversions
"><heading>Diversions - overriding a
10589 package's version of a file (from old Packaging Manual)
10593 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10594 when it reinstalls the package it belongs to, and to have it
10595 put the file from the package somewhere else instead.
10599 This can be used locally to override a package's version of a
10600 file, or by one package to override another's version (or
10601 provide a wrapper for it).
10605 Before deciding to use a diversion, read <ref
10606 id="pkg-alternatives
"> to see if you really want a diversion
10607 rather than several alternative versions of a program.
10611 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10612 and updated by a special program <prgn>dpkg-divert</prgn>.
10613 Please see <manref name="dpkg-divert
" section="8"> for full
10614 details of its operation.
10618 When a package wishes to divert a file from another, it should
10619 call <prgn>dpkg-divert</prgn> in its preinst to add the
10620 diversion and rename the existing file. For example,
10621 supposing that a <prgn>smailwrapper</prgn> package wishes to
10622 install a wrapper around <file>/usr/sbin/smail</file>:
10624 dpkg-divert --package smailwrapper --add --rename \
10625 --divert /usr/sbin/smail.real /usr/sbin/smail
10626 </example> The <tt>--package smailwrapper</tt> ensures that
10627 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10628 can bypass the diversion and get installed as the true version.
10629 It's safe to add the diversion unconditionally on upgrades since
10630 it will be left unchanged if it already exists, but
10631 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10632 message, make the command conditional on the version from which
10633 the package is being upgraded:
10635 if [ upgrade != "$
1" ] || dpkg --compare-versions "$
2" lt 1.0-2; then
10636 dpkg-divert --package smailwrapper --add --rename \
10637 --divert /usr/sbin/smail.real /usr/sbin/smail
10639 </example> where <tt>1.0-2</tt> is the version at which the
10640 diversion was first added to the package. Running the command
10641 during abort-upgrade is pointless but harmless.
10645 The postrm has to do the reverse:
10647 if [ remove = "$
1" -o abort-install = "$
1" -o disappear = "$
1" ]; then
10648 dpkg-divert --package smailwrapper --remove --rename \
10649 --divert /usr/sbin/smail.real /usr/sbin/smail
10651 </example> If the diversion was added at a particular version, the
10652 postrm should also handle the failure case of upgrading from an
10653 older version (unless the older version is so old that direct
10654 upgrades are no longer supported):
10656 if [ abort-upgrade = "$
1" ] && dpkg --compare-versions "$
2" lt 1.0-2; then
10657 dpkg-divert --package smailwrapper --remove --rename \
10658 --divert /usr/sbin/smail.real /usr/sbin/smail
10660 </example> where <tt>1.02-2</tt> is the version at which the
10661 diversion was first added to the package. The postrm should not
10662 remove the diversion on upgrades both because there's no reason to
10663 remove the diversion only to immediately re-add it and since the
10664 postrm of the old package is run after unpacking so the removal of
10665 the diversion will fail.
10669 Do not attempt to divert a file which is vitally important for
10670 the system's operation - when using <prgn>dpkg-divert</prgn>
10671 there is a time, after it has been diverted but before
10672 <prgn>dpkg</prgn> has installed the new version, when the file
10673 does not exist.</p>
10678 <!-- Local variables: -->
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