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>comm</em>,
674 <em>devel</em>, <em>doc</em>,
675 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
676 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
677 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
678 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
679 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
681 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
682 <em>science</em>, <em>shells</em>,
683 <em>sound</em>, <em>tex</em>, <em>text</em>,
684 <em>utils</em>, <em>web</em>, <em>x11</em>.
688 <sect id="priorities">
689 <heading>Priorities</heading>
692 Each package should have a <em>priority</em> value, which is
693 included in the package's <em>control record</em>
694 (see <ref id="f-Priority">).
695 This information is used by the Debian package management tools to
696 separate high-priority packages from less-important packages.
700 The following <em>priority levels</em> are recognized by the
701 Debian package management tools.
703 <tag><tt>required</tt></tag>
705 Packages which are necessary for the proper
706 functioning of the system (usually, this means that
707 dpkg functionality depends on these packages).
708 Removing a <tt>required</tt> package may cause your
709 system to become totally broken and you may not even
710 be able to use <prgn>dpkg</prgn> to put things back,
711 so only do so if you know what you are doing. Systems
712 with only the <tt>required</tt> packages are probably
713 unusable, but they do have enough functionality to
714 allow the sysadmin to boot and install more software.
716 <tag><tt>important</tt></tag>
718 Important programs, including those which one would
719 expect to find on any Unix-like system. If the
720 expectation is that an experienced Unix person who
721 found it missing would say "What on earth is going on,
722 where is <prgn>foo</prgn>?", it must be an
723 <tt>important</tt> package.<footnote>
724 This is an important criterion because we are
725 trying to produce, amongst other things, a free
728 Other packages without which the system will not run
729 well or be usable must also have priority
730 <tt>important</tt>. This does
731 <em>not</em> include Emacs, the X Window System, TeX
732 or any other large applications. The
733 <tt>important</tt> packages are just a bare minimum of
734 commonly-expected and necessary tools.
736 <tag><tt>standard</tt></tag>
738 These packages provide a reasonably small but not too
739 limited character-mode system. This is what will be
740 installed by default if the user doesn't select anything
741 else. It doesn't include many large applications.
743 <tag><tt>optional</tt></tag>
745 (In a sense everything that isn't required is
746 optional, but that's not what is meant here.) This is
747 all the software that you might reasonably want to
748 install if you didn't know what it was and don't have
749 specialized requirements. This is a much larger system
750 and includes the X Window System, a full TeX
751 distribution, and many applications. Note that
752 optional packages should not conflict with each other.
754 <tag><tt>extra</tt></tag>
756 This contains all packages that conflict with others
757 with required, important, standard or optional
758 priorities, or are only likely to be useful if you
759 already know what they are or have specialized
760 requirements (such as packages containing only detached
767 Packages must not depend on packages with lower priority
768 values (excluding build-time dependencies). In order to
769 ensure this, the priorities of one or more packages may need
778 <heading>Binary packages</heading>
781 The Debian GNU/Linux distribution is based on the Debian
782 package management system, called <prgn>dpkg</prgn>. Thus,
783 all packages in the Debian distribution must be provided
784 in the <tt>.deb</tt> file format.
788 <heading>The package name</heading>
791 Every package must have a name that's unique within the Debian
796 The package name is included in the control field
797 <tt>Package</tt>, the format of which is described
798 in <ref id="f-Package">.
799 The package name is also included as a part of the file name
800 of the <tt>.deb</tt> file.
805 <heading>The version of a package</heading>
808 Every package has a version number recorded in its
809 <tt>Version</tt> control file field, described in
810 <ref id="f-Version">.
814 The package management system imposes an ordering on version
815 numbers, so that it can tell whether packages are being up- or
816 downgraded and so that package system front end applications
817 can tell whether a package it finds available is newer than
818 the one installed on the system. The version number format
819 has the most significant parts (as far as comparison is
820 concerned) at the beginning.
824 If an upstream package has problematic version numbers they
825 should be converted to a sane form for use in the
826 <tt>Version</tt> field.
830 <heading>Version numbers based on dates</heading>
833 In general, Debian packages should use the same version
834 numbers as the upstream sources.
838 However, in some cases where the upstream version number is
839 based on a date (e.g., a development "snapshot" release) the
840 package management system cannot handle these version
841 numbers without epochs. For example, dpkg will consider
842 "96May01" to be greater than "96Dec24".
846 To prevent having to use epochs for every new upstream
847 version, the date based portion of the version number
848 should be changed to the following format in such cases:
849 "19960501", "19961224". It is up to the maintainer whether
850 they want to bother the upstream maintainer to change
851 the version numbers upstream, too.
855 Note that other version formats based on dates which are
856 parsed correctly by the package management system should
857 <em>not</em> be changed.
861 Native Debian packages (i.e., packages which have been
862 written especially for Debian) whose version numbers include
863 dates should always use the "YYYYMMDD" format.
870 <heading>The maintainer of a package</heading>
873 Every package must have a Debian maintainer (the
874 maintainer may be one person or a group of people
875 reachable from a common email address, such as a mailing
876 list). The maintainer is responsible for ensuring that
877 the package is placed in the appropriate distributions.
881 The maintainer must be specified in the
882 <tt>Maintainer</tt> control field with their correct name
883 and a working email address. If one person maintains
884 several packages, they should try to avoid having
885 different forms of their name and email address in
886 the <tt>Maintainer</tt> fields of those packages.
890 The format of the <tt>Maintainer</tt> control field is
891 described in <ref id="f-Maintainer">.
895 If the maintainer of a package quits from the Debian
896 project, "Debian QA Group"
897 <email>packages@qa.debian.org</email> takes over the
898 maintainer-ship of the package until someone else
899 volunteers for that task. These packages are called
900 <em>orphaned packages</em>.<footnote>
901 The detailed procedure for doing this gracefully can
902 be found in the Debian Developer's Reference,
903 see <ref id="related">.
908 <sect id="descriptions">
909 <heading>The description of a package</heading>
912 Every Debian package must have an extended description
913 stored in the appropriate field of the control record.
914 The technical information about the format of the
915 <tt>Description</tt> field is in <ref id="f-Description">.
919 The description should describe the package (the program) to a
920 user (system administrator) who has never met it before so that
921 they have enough information to decide whether they want to
922 install it. This description should not just be copied verbatim
923 from the program's documentation.
927 Put important information first, both in the synopsis and
928 extended description. Sometimes only the first part of the
929 synopsis or of the description will be displayed. You can
930 assume that there will usually be a way to see the whole
931 extended description.
935 The description should also give information about the
936 significant dependencies and conflicts between this package
937 and others, so that the user knows why these dependencies and
938 conflicts have been declared.
942 Instructions for configuring or using the package should
943 not be included (that is what installation scripts,
944 manual pages, info files, etc., are for). Copyright
945 statements and other administrivia should not be included
946 either (that is what the copyright file is for).
949 <sect1 id="synopsis"><heading>The single line synopsis</heading>
952 The single line synopsis should be kept brief - certainly
957 Do not include the package name in the synopsis line. The
958 display software knows how to display this already, and you
959 do not need to state it. Remember that in many situations
960 the user may only see the synopsis line - make it as
961 informative as you can.
966 <sect1 id="extendeddesc"><heading>The extended description</heading>
969 Do not try to continue the single line synopsis into the
970 extended description. This will not work correctly when
971 the full description is displayed, and makes no sense
972 where only the summary (the single line synopsis) is
977 The extended description should describe what the package
978 does and how it relates to the rest of the system (in terms
979 of, for example, which subsystem it is which part of).
983 The description field needs to make sense to anyone, even
984 people who have no idea about any of the things the
985 package deals with.<footnote>
986 The blurb that comes with a program in its
987 announcements and/or <prgn>README</prgn> files is
988 rarely suitable for use in a description. It is
989 usually aimed at people who are already in the
990 community where the package is used.
999 <heading>Dependencies</heading>
1002 Every package must specify the dependency information
1003 about other packages that are required for the first to
1008 For example, a dependency entry must be provided for any
1009 shared libraries required by a dynamically-linked executable
1010 binary in a package.
1014 Packages are not required to declare any dependencies they
1015 have on other packages which are marked <tt>Essential</tt>
1016 (see below), and should not do so unless they depend on a
1017 particular version of that package.<footnote>
1019 Essential is needed in part to avoid unresolvable dependency
1020 loops on upgrade. If packages add unnecessary dependencies
1021 on packages in this set, the chances that there
1022 <strong>will</strong> be an unresolvable dependency loop
1023 caused by forcing these Essential packages to be configured
1024 first before they need to be is greatly increased. It also
1025 increases the chances that frontends will be unable to
1026 <strong>calculate</strong> an upgrade path, even if one
1030 Also, functionality is rarely ever removed from the
1031 Essential set, but <em>packages</em> have been removed from
1032 the Essential set when the functionality moved to a
1033 different package. So depending on these packages <em>just
1034 in case</em> they stop being essential does way more harm
1041 Sometimes, a package requires another package to be installed
1042 <em>and</em> configured before it can be installed. In this
1043 case, you must specify a <tt>Pre-Depends</tt> entry for
1048 You should not specify a <tt>Pre-Depends</tt> entry for a
1049 package before this has been discussed on the
1050 <tt>debian-devel</tt> mailing list and a consensus about
1051 doing that has been reached.
1055 The format of the package interrelationship control fields is
1056 described in <ref id="relationships">.
1060 <sect id="virtual_pkg">
1061 <heading>Virtual packages</heading>
1064 Sometimes, there are several packages which offer
1065 more-or-less the same functionality. In this case, it's
1066 useful to define a <em>virtual package</em> whose name
1067 describes that common functionality. (The virtual
1068 packages only exist logically, not physically; that's why
1069 they are called <em>virtual</em>.) The packages with this
1070 particular function will then <em>provide</em> the virtual
1071 package. Thus, any other package requiring that function
1072 can simply depend on the virtual package without having to
1073 specify all possible packages individually.
1077 All packages should use virtual package names where
1078 appropriate, and arrange to create new ones if necessary.
1079 They should not use virtual package names (except privately,
1080 amongst a cooperating group of packages) unless they have
1081 been agreed upon and appear in the list of virtual package
1082 names. (See also <ref id="virtual">)
1086 The latest version of the authoritative list of virtual
1087 package names can be found in the <tt>debian-policy</tt> package.
1088 It is also available from the Debian web mirrors at
1089 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1090 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1094 The procedure for updating the list is described in the preface
1101 <heading>Base system</heading>
1104 The <tt>base system</tt> is a minimum subset of the Debian
1105 GNU/Linux system that is installed before everything else
1106 on a new system. Only very few packages are allowed to form
1107 part of the base system, in order to keep the required disk
1112 The base system consists of all those packages with priority
1113 <tt>required</tt> or <tt>important</tt>. Many of them will
1114 be tagged <tt>essential</tt> (see below).
1119 <heading>Essential packages</heading>
1122 Essential is defined as the minimal set of functionality that
1123 must be available and usable on the system at all times, even
1124 when packages are in an unconfigured (but unpacked) state.
1125 Packages are tagged <tt>essential</tt> for a system using the
1126 <tt>Essential</tt> control file field. The format of the
1127 <tt>Essential</tt> control field is described in <ref
1132 Since these packages cannot be easily removed (one has to
1133 specify an extra <em>force option</em> to
1134 <prgn>dpkg</prgn> to do so), this flag must not be used
1135 unless absolutely necessary. A shared library package
1136 must not be tagged <tt>essential</tt>; dependencies will
1137 prevent its premature removal, and we need to be able to
1138 remove it when it has been superseded.
1142 Since dpkg will not prevent upgrading of other packages
1143 while an <tt>essential</tt> package is in an unconfigured
1144 state, all <tt>essential</tt> packages must supply all of
1145 their core functionality even when unconfigured. If the
1146 package cannot satisfy this requirement it must not be
1147 tagged as essential, and any packages depending on this
1148 package must instead have explicit dependency fields as
1153 Maintainers should take great care in adding any programs,
1154 interfaces, or functionality to <tt>essential</tt> packages.
1155 Packages may assume that functionality provided by
1156 <tt>essential</tt> packages is always available without
1157 declaring explicit dependencies, which means that removing
1158 functionality from the Essential set is very difficult and is
1159 almost never done. Any capability added to an
1160 <tt>essential</tt> package therefore creates an obligation to
1161 support that capability as part of the Essential set in
1166 You must not tag any packages <tt>essential</tt> before
1167 this has been discussed on the <tt>debian-devel</tt>
1168 mailing list and a consensus about doing that has been
1173 <sect id="maintscripts">
1174 <heading>Maintainer Scripts</heading>
1177 The package installation scripts should avoid producing
1178 output which is unnecessary for the user to see and
1179 should rely on <prgn>dpkg</prgn> to stave off boredom on
1180 the part of a user installing many packages. This means,
1181 amongst other things, using the <tt>--quiet</tt> option on
1182 <prgn>install-info</prgn>.
1186 Errors which occur during the execution of an installation
1187 script must be checked and the installation must not
1188 continue after an error.
1192 Note that in general <ref id="scripts"> applies to package
1193 maintainer scripts, too.
1197 You should not use <prgn>dpkg-divert</prgn> on a file
1198 belonging to another package without consulting the
1199 maintainer of that package first.
1203 All packages which supply an instance of a common command
1204 name (or, in general, filename) should generally use
1205 <prgn>update-alternatives</prgn>, so that they may be
1206 installed together. If <prgn>update-alternatives</prgn>
1207 is not used, then each package must use
1208 <tt>Conflicts</tt> to ensure that other packages are
1209 de-installed. (In this case, it may be appropriate to
1210 specify a conflict against earlier versions of something
1211 that previously did not use
1212 <prgn>update-alternatives</prgn>; this is an exception to
1213 the usual rule that versioned conflicts should be
1217 <sect1 id="maintscriptprompt">
1218 <heading>Prompting in maintainer scripts</heading>
1220 Package maintainer scripts may prompt the user if
1221 necessary. Prompting should be done by communicating
1222 through a program, such as <prgn>debconf</prgn>, which
1223 conforms to the Debian Configuration Management
1224 Specification, version 2 or higher. Prompting the user by
1225 other means, such as by hand<footnote>
1226 From the Jargon file: by hand 2. By extension,
1227 writing code which does something in an explicit or
1228 low-level way for which a presupplied library
1229 (<em>debconf, in this instance</em>) routine ought
1230 to have been available.
1231 </footnote>, is now deprecated.
1235 The Debian Configuration Management Specification is included
1236 in the <file>debconf_specification</file> files in the
1237 <package>debian-policy</package> package.
1238 It is also available from the Debian web mirrors at
1239 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1240 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1244 Packages which use the Debian Configuration Management
1245 Specification may contain an additional
1246 <prgn>config</prgn> script and a <tt>templates</tt>
1247 file in their control archive<footnote>
1248 The control.tar.gz inside the .deb.
1249 See <manref name="deb" section="5">.
1251 The <prgn>config</prgn> script might be run before the
1252 <prgn>preinst</prgn> script, and before the package is unpacked
1253 or any of its dependencies or pre-dependencies are satisfied.
1254 Therefore it must work using only the tools present in
1255 <em>essential</em> packages.<footnote>
1256 <package>Debconf</package> or another tool that
1257 implements the Debian Configuration Management
1258 Specification will also be installed, and any
1259 versioned dependencies on it will be satisfied
1260 before preconfiguration begins.
1265 Packages which use the Debian Configuration Management
1266 Specification must allow for translation of their user-visible
1267 messages by using a gettext-based system such as the one
1268 provided by the <package>po-debconf</package> package.
1272 Packages should try to minimize the amount of prompting
1273 they need to do, and they should ensure that the user
1274 will only ever be asked each question once. This means
1275 that packages should try to use appropriate shared
1276 configuration files (such as <file>/etc/papersize</file> and
1277 <file>/etc/news/server</file>), and shared
1278 <package>debconf</package> variables rather than each
1279 prompting for their own list of required pieces of
1284 It also means that an upgrade should not ask the same
1285 questions again, unless the user has used
1286 <tt>dpkg --purge</tt> to remove the package's configuration.
1287 The answers to configuration questions should be stored in an
1288 appropriate place in <file>/etc</file> so that the user can
1289 modify them, and how this has been done should be
1294 If a package has a vitally important piece of
1295 information to pass to the user (such as "don't run me
1296 as I am, you must edit the following configuration files
1297 first or you risk your system emitting badly-formatted
1298 messages"), it should display this in the
1299 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1300 prompt the user to hit return to acknowledge the
1301 message. Copyright messages do not count as vitally
1302 important (they belong in
1303 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1304 neither do instructions on how to use a program (these
1305 should be in on-line documentation, where all the users
1310 Any necessary prompting should almost always be confined
1311 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1312 script. If it is done in the <prgn>postinst</prgn>, it
1313 should be protected with a conditional so that
1314 unnecessary prompting doesn't happen if a package's
1315 installation fails and the <prgn>postinst</prgn> is
1316 called with <tt>abort-upgrade</tt>,
1317 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1327 <heading>Source packages</heading>
1329 <sect id="standardsversion">
1330 <heading>Standards conformance</heading>
1333 Source packages should specify the most recent version number
1334 of this policy document with which your package complied
1335 when it was last updated.
1339 This information may be used to file bug reports
1340 automatically if your package becomes too much out of date.
1344 The version is specified in the <tt>Standards-Version</tt>
1346 The format of the <tt>Standards-Version</tt> field is
1347 described in <ref id="f-Standards-Version">.
1351 You should regularly, and especially if your package has
1352 become out of date, check for the newest Policy Manual
1353 available and update your package, if necessary. When your
1354 package complies with the new standards you should update the
1355 <tt>Standards-Version</tt> source package field and
1356 release it.<footnote>
1357 See the file <file>upgrading-checklist</file> for
1358 information about policy which has changed between
1359 different versions of this document.
1365 <sect id="pkg-relations">
1366 <heading>Package relationships</heading>
1369 Source packages should specify which binary packages they
1370 require to be installed or not to be installed in order to
1371 build correctly. For example, if building a package
1372 requires a certain compiler, then the compiler should be
1373 specified as a build-time dependency.
1377 It is not necessary to explicitly specify build-time
1378 relationships on a minimal set of packages that are always
1379 needed to compile, link and put in a Debian package a
1380 standard "Hello World!" program written in C or C++. The
1381 required packages are called <em>build-essential</em>, and
1382 an informational list can be found in
1383 <file>/usr/share/doc/build-essential/list</file> (which is
1384 contained in the <tt>build-essential</tt>
1387 <list compact="compact">
1389 This allows maintaining the list separately
1390 from the policy documents (the list does not
1391 need the kind of control that the policy
1395 Having a separate package allows one to install
1396 the build-essential packages on a machine, as
1397 well as allowing other packages such as tasks to
1398 require installation of the build-essential
1399 packages using the depends relation.
1402 The separate package allows bug reports against
1403 the list to be categorized separately from
1404 the policy management process in the BTS.
1411 When specifying the set of build-time dependencies, one
1412 should list only those packages explicitly required by the
1413 build. It is not necessary to list packages which are
1414 required merely because some other package in the list of
1415 build-time dependencies depends on them.<footnote>
1416 The reason for this is that dependencies change, and
1417 you should list all those packages, and <em>only</em>
1418 those packages that <em>you</em> need directly. What
1419 others need is their business. For example, if you
1420 only link against <file>libimlib</file>, you will need to
1421 build-depend on <package>libimlib2-dev</package> but
1422 not against any <tt>libjpeg*</tt> packages, even
1423 though <tt>libimlib2-dev</tt> currently depends on
1424 them: installation of <package>libimlib2-dev</package>
1425 will automatically ensure that all of its run-time
1426 dependencies are satisfied.
1431 If build-time dependencies are specified, it must be
1432 possible to build the package and produce working binaries
1433 on a system with only essential and build-essential
1434 packages installed and also those required to satisfy the
1435 build-time relationships (including any implied
1436 relationships). In particular, this means that version
1437 clauses should be used rigorously in build-time
1438 relationships so that one cannot produce bad or
1439 inconsistently configured packages when the relationships
1440 are properly satisfied.
1444 <ref id="relationships"> explains the technical details.
1449 <heading>Changes to the upstream sources</heading>
1452 If changes to the source code are made that are not
1453 specific to the needs of the Debian system, they should be
1454 sent to the upstream authors in whatever form they prefer
1455 so as to be included in the upstream version of the
1460 If you need to configure the package differently for
1461 Debian or for Linux, and the upstream source doesn't
1462 provide a way to do so, you should add such configuration
1463 facilities (for example, a new <prgn>autoconf</prgn> test
1464 or <tt>#define</tt>) and send the patch to the upstream
1465 authors, with the default set to the way they originally
1466 had it. You can then easily override the default in your
1467 <file>debian/rules</file> or wherever is appropriate.
1471 You should make sure that the <prgn>configure</prgn> utility
1472 detects the correct architecture specification string
1473 (refer to <ref id="arch-spec"> for details).
1477 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1478 <prgn>configure</prgn> scripts are used, you should edit the
1479 <file>.in</file> files rather than editing the
1480 <prgn>Makefile</prgn> directly. This allows the user to
1481 reconfigure the package if necessary. You should
1482 <em>not</em> configure the package and edit the generated
1483 <prgn>Makefile</prgn>! This makes it impossible for someone
1484 else to later reconfigure the package without losing the
1490 <sect id="dpkgchangelog">
1491 <heading>Debian changelog: <file>debian/changelog</file></heading>
1494 Changes in the Debian version of the package should be
1495 briefly explained in the Debian changelog file
1496 <file>debian/changelog</file>.<footnote>
1498 Mistakes in changelogs are usually best rectified by
1499 making a new changelog entry rather than "rewriting
1500 history" by editing old changelog entries.
1503 This includes modifications
1504 made in the Debian package compared to the upstream one
1505 as well as other changes and updates to the package.
1507 Although there is nothing stopping an author who is also
1508 the Debian maintainer from using this changelog for all
1509 their changes, it will have to be renamed if the Debian
1510 and upstream maintainers become different people. In such
1511 a case, however, it might be better to maintain the package
1512 as a non-native package.
1517 The format of the <file>debian/changelog</file> allows the
1518 package building tools to discover which version of the package
1519 is being built and find out other release-specific information.
1523 That format is a series of entries like this:
1525 <example compact="compact">
1526 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1528 [optional blank line(s), stripped]
1530 * <var>change details</var>
1531 <var>more change details</var>
1533 [blank line(s), included in output of dpkg-parsechangelog]
1535 * <var>even more change details</var>
1537 [optional blank line(s), stripped]
1539 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1544 <var>package</var> and <var>version</var> are the source
1545 package name and version number.
1549 <var>distribution(s)</var> lists the distributions where
1550 this version should be installed when it is uploaded - it
1551 is copied to the <tt>Distribution</tt> field in the
1552 <file>.changes</file> file. See <ref id="f-Distribution">.
1556 <var>urgency</var> is the value for the <tt>Urgency</tt>
1557 field in the <file>.changes</file> file for the upload
1558 (see <ref id="f-Urgency">). It is not possible to specify
1559 an urgency containing commas; commas are used to separate
1560 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1561 <prgn>dpkg</prgn> changelog format (though there is
1562 currently only one useful <var>keyword</var>,
1567 The change details may in fact be any series of lines
1568 starting with at least two spaces, but conventionally each
1569 change starts with an asterisk and a separating space and
1570 continuation lines are indented so as to bring them in
1571 line with the start of the text above. Blank lines may be
1572 used here to separate groups of changes, if desired.
1576 If this upload resolves bugs recorded in the Bug Tracking
1577 System (BTS), they may be automatically closed on the
1578 inclusion of this package into the Debian archive by
1579 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1580 in the change details.<footnote>
1581 To be precise, the string should match the following
1582 Perl regular expression:
1584 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1586 Then all of the bug numbers listed will be closed by the
1587 archive maintenance script (<prgn>katie</prgn>) using the
1588 <var>version</var> of the changelog entry.
1590 This information is conveyed via the <tt>Closes</tt> field
1591 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1595 The maintainer name and email address used in the changelog
1596 should be the details of the person uploading <em>this</em>
1597 version. They are <em>not</em> necessarily those of the
1598 usual package maintainer. The information here will be
1599 copied to the <tt>Changed-By</tt> field in the
1600 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1601 and then later used to send an acknowledgement when the
1602 upload has been installed.
1606 The <var>date</var> must be in RFC822 format<footnote>
1607 This is generated by <tt>date -R</tt>.
1608 </footnote>; it must include the time zone specified
1609 numerically, with the time zone name or abbreviation
1610 optionally present as a comment in parentheses.
1614 The first "title" line with the package name must start
1615 at the left hand margin. The "trailer" line with the
1616 maintainer and date details must be preceded by exactly
1617 one space. The maintainer details and the date must be
1618 separated by exactly two spaces.
1622 The entire changelog must be encoded in UTF-8.
1626 For more information on placement of the changelog files
1627 within binary packages, please see <ref id="changelogs">.
1631 <sect id="dpkgcopyright">
1632 <heading>Copyright: <file>debian/copyright</file></heading>
1634 Every package must be accompanied by a verbatim copy of
1635 its copyright and distribution license in the file
1636 <file>/usr/share/doc/<var>package</var>/copyright</file>
1637 (see <ref id="copyrightfile"> for further details). Also see
1638 <ref id="pkgcopyright"> for further considerations relayed
1639 to copyrights for packages.
1643 <heading>Error trapping in makefiles</heading>
1646 When <prgn>make</prgn> invokes a command in a makefile
1647 (including your package's upstream makefiles and
1648 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1649 means that <prgn>sh</prgn>'s usual bad error handling
1650 properties apply: if you include a miniature script as one
1651 of the commands in your makefile you'll find that if you
1652 don't do anything about it then errors are not detected
1653 and <prgn>make</prgn> will blithely continue after
1658 Every time you put more than one shell command (this
1659 includes using a loop) in a makefile command you
1660 must make sure that errors are trapped. For
1661 simple compound commands, such as changing directory and
1662 then running a program, using <tt>&&</tt> rather
1663 than semicolon as a command separator is sufficient. For
1664 more complex commands including most loops and
1665 conditionals you should include a separate <tt>set -e</tt>
1666 command at the start of every makefile command that's
1667 actually one of these miniature shell scripts.
1671 <sect id="timestamps">
1672 <heading>Time Stamps</heading>
1674 Maintainers should preserve the modification times of the
1675 upstream source files in a package, as far as is reasonably
1677 The rationale is that there is some information conveyed
1678 by knowing the age of the file, for example, you could
1679 recognize that some documentation is very old by looking
1680 at the modification time, so it would be nice if the
1681 modification time of the upstream source would be
1687 <sect id="restrictions">
1688 <heading>Restrictions on objects in source packages</heading>
1691 The source package may not contain any hard links<footnote>
1693 This is not currently detected when building source
1694 packages, but only when extracting
1698 Hard links may be permitted at some point in the
1699 future, but would require a fair amount of
1702 </footnote>, device special files, sockets or setuid or
1703 setgid files.<footnote>
1704 Setgid directories are allowed.
1709 <sect id="debianrules">
1710 <heading>Main building script: <file>debian/rules</file></heading>
1713 This file must be an executable makefile, and contains the
1714 package-specific recipes for compiling the package and
1715 building binary package(s) from the source.
1719 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1720 so that it can be invoked by saying its name rather than
1721 invoking <prgn>make</prgn> explicitly.
1725 Since an interactive <file>debian/rules</file> script makes it
1726 impossible to auto-compile that package and also makes it
1727 hard for other people to reproduce the same binary
1728 package, all <em>required targets</em> MUST be
1729 non-interactive. At a minimum, required targets are the
1730 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1731 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1732 <em>binary-indep</em>, and <em>build</em>. It also follows
1733 that any target that these targets depend on must also be
1738 The targets are as follows (required unless stated otherwise):
1740 <tag><tt>build</tt></tag>
1743 The <tt>build</tt> target should perform all the
1744 configuration and compilation of the package.
1745 If a package has an interactive pre-build
1746 configuration routine, the Debianized source package
1747 must either be built after this has taken place (so
1748 that the binary package can be built without rerunning
1749 the configuration) or the configuration routine
1750 modified to become non-interactive. (The latter is
1751 preferable if there are architecture-specific features
1752 detected by the configuration routine.)
1756 For some packages, notably ones where the same
1757 source tree is compiled in different ways to produce
1758 two binary packages, the <tt>build</tt> target
1759 does not make much sense. For these packages it is
1760 good enough to provide two (or more) targets
1761 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1762 for each of the ways of building the package, and a
1763 <tt>build</tt> target that does nothing. The
1764 <tt>binary</tt> target will have to build the
1765 package in each of the possible ways and make the
1766 binary package out of each.
1770 The <tt>build</tt> target must not do anything
1771 that might require root privilege.
1775 The <tt>build</tt> target may need to run the
1776 <tt>clean</tt> target first - see below.
1780 When a package has a configuration and build routine
1781 which takes a long time, or when the makefiles are
1782 poorly designed, or when <tt>build</tt> needs to
1783 run <tt>clean</tt> first, it is a good idea to
1784 <tt>touch build</tt> when the build process is
1785 complete. This will ensure that if <tt>debian/rules
1786 build</tt> is run again it will not rebuild the whole
1788 Another common way to do this is for <tt>build</tt>
1789 to depend on <prgn>build-stamp</prgn> and to do
1790 nothing else, and for the <prgn>build-stamp</prgn>
1791 target to do the building and to <tt>touch
1792 build-stamp</tt> on completion. This is
1793 especially useful if the build routine creates a
1794 file or directory called <tt>build</tt>; in such a
1795 case, <tt>build</tt> will need to be listed as
1796 a phony target (i.e., as a dependency of the
1797 <tt>.PHONY</tt> target). See the documentation of
1798 <prgn>make</prgn> for more information on phony
1804 <tag><tt>build-arch</tt> (optional),
1805 <tt>build-indep</tt> (optional)
1809 A package may also provide both of the targets
1810 <tt>build-arch</tt> and <tt>build-indep</tt>.
1811 The <tt>build-arch</tt> target, if provided, should
1812 perform all the configuration and compilation required
1813 for producing all architecture-dependant binary packages
1814 (those packages for which the body of the
1815 <tt>Architecture</tt> field in <tt>debian/control</tt>
1816 is not <tt>all</tt>).
1817 Similarly, the <tt>build-indep</tt> target, if
1818 provided, should perform all the configuration and
1819 compilation required for producing all
1820 architecture-independent binary packages
1821 (those packages for which the body of the
1822 <tt>Architecture</tt> field in <tt>debian/control</tt>
1824 The <tt>build</tt> target should depend on those of the
1825 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1826 are provided in the rules file.
1830 If one or both of the targets <tt>build-arch</tt> and
1831 <tt>build-indep</tt> are not provided, then invoking
1832 <file>debian/rules</file> with one of the not-provided
1833 targets as arguments should produce a exit status code
1834 of 2. Usually this is provided automatically by make
1835 if the target is missing.
1839 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1840 must not do anything that might require root privilege.
1844 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1845 <tt>binary-indep</tt>
1849 The <tt>binary</tt> target must be all that is
1850 necessary for the user to build the binary package(s)
1851 produced from this source package. It is
1852 split into two parts: <prgn>binary-arch</prgn> builds
1853 the binary packages which are specific to a particular
1854 architecture, and <tt>binary-indep</tt> builds
1855 those which are not.
1858 <tt>binary</tt> may be (and commonly is) a target with
1859 no commands which simply depends on
1860 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1863 Both <tt>binary-*</tt> targets should depend on the
1864 <tt>build</tt> target, or on the appropriate
1865 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1866 provided, so that the package is built if it has not
1867 been already. It should then create the relevant
1868 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1869 make their control files and <prgn>dpkg-deb</prgn> to
1870 build them and place them in the parent of the top
1875 Both the <tt>binary-arch</tt> and
1876 <tt>binary-indep</tt> targets <em>must</em> exist.
1877 If one of them has nothing to do (which will always be
1878 the case if the source generates only a single binary
1879 package, whether architecture-dependent or not), it
1880 must still exist and must always succeed.
1884 The <tt>binary</tt> targets must be invoked as
1886 The <prgn>fakeroot</prgn> package often allows one
1887 to build a package correctly even without being
1893 <tag><tt>clean</tt></tag>
1896 This must undo any effects that the <tt>build</tt>
1897 and <tt>binary</tt> targets may have had, except
1898 that it should leave alone any output files created in
1899 the parent directory by a run of a <tt>binary</tt>
1904 If a <tt>build</tt> file is touched at the end of
1905 the <tt>build</tt> target, as suggested above, it
1906 should be removed as the first action that
1907 <tt>clean</tt> performs, so that running
1908 <tt>build</tt> again after an interrupted
1909 <tt>clean</tt> doesn't think that everything is
1914 The <tt>clean</tt> target may need to be
1915 invoked as root if <tt>binary</tt> has been
1916 invoked since the last <tt>clean</tt>, or if
1917 <tt>build</tt> has been invoked as root (since
1918 <tt>build</tt> may create directories, for
1923 <tag><tt>get-orig-source</tt> (optional)</tag>
1926 This target fetches the most recent version of the
1927 original source package from a canonical archive site
1928 (via FTP or WWW, for example), does any necessary
1929 rearrangement to turn it into the original source
1930 tar file format described below, and leaves it in the
1935 This target may be invoked in any directory, and
1936 should take care to clean up any temporary files it
1941 This target is optional, but providing it if
1942 possible is a good idea.
1946 <tag><tt>patch</tt> (optional)</tag>
1949 This target performs whatever additional actions are
1950 required to make the source ready for editing (unpacking
1951 additional upstream archives, applying patches, etc.).
1952 It is recommended to be implemented for any package where
1953 <tt>dpkg-source -x</tt> does not result in source ready
1954 for additional modification. See
1955 <ref id="readmesource">.
1961 The <tt>build</tt>, <tt>binary</tt> and
1962 <tt>clean</tt> targets must be invoked with the current
1963 directory being the package's top-level directory.
1968 Additional targets may exist in <file>debian/rules</file>,
1969 either as published or undocumented interfaces or for the
1970 package's internal use.
1974 The architectures we build on and build for are determined
1975 by <prgn>make</prgn> variables using the utility
1976 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1977 You can determine the
1978 Debian architecture and the GNU style architecture
1979 specification string for the build machine (the machine type
1980 we are building on) as well as for the host machine (the
1981 machine type we are building for). Here is a list of
1982 supported <prgn>make</prgn> variables:
1983 <list compact="compact">
1985 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1988 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1989 specification string)
1992 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
1993 <tt>DEB_*_GNU_TYPE</tt>)
1996 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1997 <tt>DEB_*_GNU_TYPE</tt>)
1999 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2000 the build machine or <tt>HOST</tt> for specification of the
2005 Backward compatibility can be provided in the rules file
2006 by setting the needed variables to suitable default
2007 values; please refer to the documentation of
2008 <prgn>dpkg-architecture</prgn> for details.
2012 It is important to understand that the <tt>DEB_*_ARCH</tt>
2013 string only determines which Debian architecture we are
2014 building on or for. It should not be used to get the CPU
2015 or system information; the GNU style variables should be
2019 <sect1 id="debianrules-options">
2020 <heading><file>debian/rules</file> and
2021 <tt>DEB_BUILD_OPTIONS</tt></heading>
2024 Supporting the standardized environment variable
2025 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2026 contain several flags to change how a package is compiled and
2027 built. Each flag must be in the form <var>flag</var> or
2028 <var>flag</var>=<var>options</var>. If multiple flags are
2029 given, they must be separated by whitespace.<footnote>
2030 Some packages support any delimiter, but whitespace is the
2031 easiest to parse inside a makefile and avoids ambiguity with
2032 flag values that contain commas.
2034 <var>flag</var> must start with a lowercase letter
2035 (<tt>a-z</tt>) and consist only of lowercase letters,
2036 numbers (<tt>0-9</tt>), and the characters
2037 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2038 <var>options</var> must not contain whitespace. The same
2039 tag should not be given multiple times with conflicting
2040 values. Package maintainers may assume that
2041 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2045 The meaning of the following tags has been standardized:
2049 This tag says to not run any build-time test suite
2050 provided by the package.
2054 The presence of this tag means that the package should
2055 be compiled with a minimum of optimization. For C
2056 programs, it is best to add <tt>-O0</tt> to
2057 <tt>CFLAGS</tt> (although this is usually the default).
2058 Some programs might fail to build or run at this level
2059 of optimization; it may be necessary to use
2060 <tt>-O1</tt>, for example.
2064 This tag means that the debugging symbols should not be
2065 stripped from the binary during installation, so that
2066 debugging information may be included in the package.
2068 <tag>parallel=n</tag>
2070 This tag means that the package should be built using up
2071 to <tt>n</tt> parallel processes if the package build
2072 system supports this.<footnote>
2073 Packages built with <tt>make</tt> can often implement
2074 this by passing the <tt>-j</tt><var>n</var> option to
2077 If the package build system does not support parallel
2078 builds, this string must be ignored. If the package
2079 build system only supports a lower level of concurrency
2080 than <var>n</var>, the package should be built using as
2081 many parallel processes as the package build system
2082 supports. It is up to the package maintainer to decide
2083 whether the package build times are long enough and the
2084 package build system is robust enough to make supporting
2085 parallel builds worthwhile.
2091 Unknown flags must be ignored by <file>debian/rules</file>.
2095 The following makefile snippet is an example of how one may
2096 implement the build options; you will probably have to
2097 massage this example in order to make it work for your
2099 <example compact="compact">
2102 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2103 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2104 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2105 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2107 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2112 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2113 INSTALL_PROGRAM += -s
2115 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2116 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2117 MAKEFLAGS += -j$(NUMJOBS)
2122 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2123 # Code to run the package test suite.
2130 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2131 <sect id="substvars">
2132 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2135 When <prgn>dpkg-gencontrol</prgn>,
2136 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2137 generate control files they perform variable substitutions
2138 on their output just before writing it. Variable
2139 substitutions have the form <tt>${<var>variable</var>}</tt>.
2140 The optional file <file>debian/substvars</file> contains
2141 variable substitutions to be used; variables can also be set
2142 directly from <file>debian/rules</file> using the <tt>-V</tt>
2143 option to the source packaging commands, and certain
2144 predefined variables are also available.
2148 The <file>debian/substvars</file> file is usually generated and
2149 modified dynamically by <file>debian/rules</file> targets, in
2150 which case it must be removed by the <tt>clean</tt> target.
2154 See <manref name="deb-substvars" section="5"> for full
2155 details about source variable substitutions, including the
2156 format of <file>debian/substvars</file>.</p>
2159 <sect id="debianwatch">
2160 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2163 This is an optional, recommended control file for the
2164 <tt>uscan</tt> utility which defines how to automatically
2165 scan ftp or http sites for newly available updates of the
2166 package. This is used by <url id="
2167 http://dehs.alioth.debian.org/"> and other Debian QA tools
2168 to help with quality control and maintenance of the
2169 distribution as a whole.
2174 <sect id="debianfiles">
2175 <heading>Generated files list: <file>debian/files</file></heading>
2178 This file is not a permanent part of the source tree; it
2179 is used while building packages to record which files are
2180 being generated. <prgn>dpkg-genchanges</prgn> uses it
2181 when it generates a <file>.changes</file> file.
2185 It should not exist in a shipped source package, and so it
2186 (and any backup files or temporary files such as
2187 <file>files.new</file><footnote>
2188 <file>files.new</file> is used as a temporary file by
2189 <prgn>dpkg-gencontrol</prgn> and
2190 <prgn>dpkg-distaddfile</prgn> - they write a new
2191 version of <tt>files</tt> here before renaming it,
2192 to avoid leaving a corrupted copy if an error
2194 </footnote>) should be removed by the
2195 <tt>clean</tt> target. It may also be wise to
2196 ensure a fresh start by emptying or removing it at the
2197 start of the <tt>binary</tt> target.
2201 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2202 package, it adds an entry to <file>debian/files</file> for the
2203 <file>.deb</file> file that will be created when <tt>dpkg-deb
2204 --build</tt> is run for that binary package. So for most
2205 packages all that needs to be done with this file is to
2206 delete it in the <tt>clean</tt> target.
2210 If a package upload includes files besides the source
2211 package and any binary packages whose control files were
2212 made with <prgn>dpkg-gencontrol</prgn> then they should be
2213 placed in the parent of the package's top-level directory
2214 and <prgn>dpkg-distaddfile</prgn> should be called to add
2215 the file to the list in <file>debian/files</file>.</p>
2218 <sect id="embeddedfiles">
2219 <heading>Convenience copies of code</heading>
2222 Some software packages include in their distribution convenience
2223 copies of code from other software packages, generally so that
2224 users compiling from source don't have to download multiple
2225 packages. Debian packages should not make use of these
2226 convenience copies unless the included package is explicitly
2227 intended to be used in this way.<footnote>
2228 For example, parts of the GNU build system work like this.
2230 If the included code is already in the Debian archive in the
2231 form of a library, the Debian packaging should ensure that
2232 binary packages reference the libraries already in Debian and
2233 the convenience copy is not used. If the included code is not
2234 already in Debian, it should be packaged separately as a
2235 prerequisite if possible.
2237 Having multiple copies of the same code in Debian is
2238 inefficient, often creates either static linking or shared
2239 library conflicts, and, most importantly, increases the
2240 difficulty of handling security vulnerabilities in the
2246 <sect id="readmesource">
2247 <heading>Source package handling:
2248 <file>debian/README.source</file></heading>
2251 If running <prgn>dpkg-source -x</prgn> on a source package
2252 doesn't produce the source of the package, ready for editing,
2253 and allow one to make changes and run
2254 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2255 without taking any additional steps, creating a
2256 <file>debian/README.source</file> documentation file is
2257 recommended. This file should explain how to do all of the
2260 <item>Generate the fully patched source, in a form ready for
2261 editing, that would be built to create Debian
2262 packages. Doing this with a <tt>patch</tt> target in
2263 <file>debian/rules</file> is recommended; see
2264 <ref id="debianrules">.</item>
2265 <item>Modify the source and save those modifications so that
2266 they will be applied when building the package.</item>
2267 <item>Remove source modifications that are currently being
2268 applied when building the package.</item>
2269 <item>Optionally, document what steps are necessary to
2270 upgrade the Debian source package to a new upstream version,
2271 if applicable.</item>
2273 This explanation should include specific commands and mention
2274 any additional required Debian packages. It should not assume
2275 familiarity with any specific Debian packaging system or patch
2280 This explanation may refer to a documentation file installed by
2281 one of the package's build dependencies provided that the
2282 referenced documentation clearly explains these tasks and is not
2283 a general reference manual.
2287 <file>debian/README.source</file> may also include any other
2288 information that would be helpful to someone modifying the
2289 source package. Even if the package doesn't fit the above
2290 description, maintainers are encouraged to document in a
2291 <file>debian/README.source</file> file any source package with a
2292 particularly complex or unintuitive source layout or build
2293 system (for example, a package that builds the same source
2294 multiple times to generate different binary packages).
2300 <chapt id="controlfields">
2301 <heading>Control files and their fields</heading>
2304 The package management system manipulates data represented in
2305 a common format, known as <em>control data</em>, stored in
2306 <em>control files</em>.
2307 Control files are used for source packages, binary packages and
2308 the <file>.changes</file> files which control the installation
2309 of uploaded files<footnote>
2310 <prgn>dpkg</prgn>'s internal databases are in a similar
2315 <sect id="controlsyntax">
2316 <heading>Syntax of control files</heading>
2319 A control file consists of one or more paragraphs of
2321 The paragraphs are also sometimes referred to as stanzas.
2323 The paragraphs are separated by blank lines. Some control
2324 files allow only one paragraph; others allow several, in
2325 which case each paragraph usually refers to a different
2326 package. (For example, in source packages, the first
2327 paragraph refers to the source package, and later paragraphs
2328 refer to binary packages generated from the source.)
2332 Each paragraph consists of a series of data fields; each
2333 field consists of the field name, followed by a colon and
2334 then the data/value associated with that field. It ends at
2335 the end of the (logical) line. Horizontal whitespace
2336 (spaces and tabs) may occur immediately before or after the
2337 value and is ignored there; it is conventional to put a
2338 single space after the colon. For example, a field might
2340 <example compact="compact">
2343 the field name is <tt>Package</tt> and the field value
2348 Many fields' values may span several lines; in this case
2349 each continuation line must start with a space or a tab.
2350 Any trailing spaces or tabs at the end of individual
2351 lines of a field value are ignored.
2355 In fields where it is specified that lines may not wrap,
2356 only a single line of data is allowed and whitespace is not
2357 significant in a field body. Whitespace must not appear
2358 inside names (of packages, architectures, files or anything
2359 else) or version numbers, or between the characters of
2360 multi-character version relationships.
2364 Field names are not case-sensitive, but it is usual to
2365 capitalize the field names using mixed case as shown below.
2369 Blank lines, or lines consisting only of spaces and tabs,
2370 are not allowed within field values or between fields - that
2371 would mean a new paragraph.
2375 All control files must be encoded in UTF-8.
2379 <sect id="sourcecontrolfiles">
2380 <heading>Source package control files -- <file>debian/control</file></heading>
2383 The <file>debian/control</file> file contains the most vital
2384 (and version-independent) information about the source package
2385 and about the binary packages it creates.
2389 The first paragraph of the control file contains information about
2390 the source package in general. The subsequent sets each describe a
2391 binary package that the source tree builds.
2395 The fields in the general paragraph (the first one, for the source
2398 <list compact="compact">
2399 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2400 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2401 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2402 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2403 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2404 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2405 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2406 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2411 The fields in the binary package paragraphs are:
2413 <list compact="compact">
2414 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2415 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2416 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2417 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2418 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2419 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2420 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2421 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2426 The syntax and semantics of the fields are described below.
2432 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2433 generate control files for binary packages (see below), by
2434 <prgn>dpkg-genchanges</prgn> to generate the
2435 <tt>.changes</tt> file to accompany the upload, and by
2436 <prgn>dpkg-source</prgn> when it creates the
2437 <file>.dsc</file> source control file as part of a source
2438 archive. Many fields are permitted to span multiple lines in
2439 <file>debian/control</file> but not in any other control
2440 file. These tools are responsible for removing the line
2441 breaks from such fields when using fields from
2442 <file>debian/control</file> to generate other control files.
2446 The fields here may contain variable references - their
2447 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2448 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2449 when they generate output control files.
2450 See <ref id="substvars"> for details.
2454 In addition to the control file syntax described <qref
2455 id="controlsyntax">above</qref>, this file may also contain
2456 comment lines starting with <tt>#</tt> without any preceding
2457 whitespace. All such lines are ignored, even in the middle of
2458 continuation lines for a multiline field, and do not end a
2464 <sect id="binarycontrolfiles">
2465 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2468 The <file>DEBIAN/control</file> file contains the most vital
2469 (and version-dependent) information about a binary package.
2473 The fields in this file are:
2475 <list compact="compact">
2476 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2477 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2478 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2479 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2480 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2481 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2482 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2483 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2484 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2485 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2486 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2487 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2492 <sect id="debiansourcecontrolfiles">
2493 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2496 This file contains a series of fields, identified and
2497 separated just like the fields in the control file of
2498 a binary package. The fields are listed below; their
2499 syntax is described above, in <ref id="pkg-controlfields">.
2501 <list compact="compact">
2502 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2503 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2504 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2505 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2506 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2507 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2508 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2509 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2510 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2511 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2512 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2517 The source package control file is generated by
2518 <prgn>dpkg-source</prgn> when it builds the source
2519 archive, from other files in the source package,
2520 described above. When unpacking, it is checked against
2521 the files and directories in the other parts of the
2527 <sect id="debianchangesfiles">
2528 <heading>Debian changes files -- <file>.changes</file></heading>
2531 The .changes files are used by the Debian archive maintenance
2532 software to process updates to packages. They contain one
2533 paragraph which contains information from the
2534 <tt>debian/control</tt> file and other data about the
2535 source package gathered via <tt>debian/changelog</tt>
2536 and <tt>debian/rules</tt>.
2540 The fields in this file are:
2542 <list compact="compact">
2543 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2544 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2545 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2546 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2547 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2548 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2549 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2550 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2551 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2552 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2553 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2554 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2555 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2556 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2561 <sect id="controlfieldslist">
2562 <heading>List of fields</heading>
2564 <sect1 id="f-Source">
2565 <heading><tt>Source</tt></heading>
2568 This field identifies the source package name.
2572 In <file>debian/control</file> or a <file>.dsc</file> file,
2573 this field must contain only the name of the source package.
2577 In a binary package control file or a <file>.changes</file>
2578 file, the source package name may be followed by a version
2579 number in parentheses<footnote>
2580 It is customary to leave a space after the package name
2581 if a version number is specified.
2583 This version number may be omitted (and is, by
2584 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2585 the <tt>Version</tt> field of the binary package in
2586 question. The field itself may be omitted from a binary
2587 package control file when the source package has the same
2588 name and version as the binary package.
2592 <sect1 id="f-Maintainer">
2593 <heading><tt>Maintainer</tt></heading>
2596 The package maintainer's name and email address. The name
2597 should come first, then the email address inside angle
2598 brackets <tt><></tt> (in RFC822 format).
2602 If the maintainer's name contains a full stop then the
2603 whole field will not work directly as an email address due
2604 to a misfeature in the syntax specified in RFC822; a
2605 program using this field as an address must check for this
2606 and correct the problem if necessary (for example by
2607 putting the name in round brackets and moving it to the
2608 end, and bringing the email address forward).
2612 <sect1 id="f-Uploaders">
2613 <heading><tt>Uploaders</tt></heading>
2616 List of the names and email addresses of co-maintainers of
2617 the package, if any. If the package has other maintainers
2618 beside the one named in the
2619 <qref id="f-Maintainer">Maintainer field</qref>, their
2620 names and email addresses should be listed here. The
2621 format is the same as that of the Maintainer tag, and
2622 multiple entries should be comma separated. Currently,
2623 this field is restricted to a single line of data. This
2624 is an optional field.
2627 Any parser that interprets the Uploaders field in
2628 <file>debian/control</file> must permit it to span multiple
2629 lines. Line breaks in an Uploaders field that spans multiple
2630 lines are not significant and the semantics of the field are
2631 the same as if the line breaks had not been present.
2635 <sect1 id="f-Changed-By">
2636 <heading><tt>Changed-By</tt></heading>
2639 The name and email address of the person who changed the
2640 said package. Usually the name of the maintainer.
2641 All the rules for the Maintainer field apply here, too.
2645 <sect1 id="f-Section">
2646 <heading><tt>Section</tt></heading>
2649 This field specifies an application area into which the package
2650 has been classified. See <ref id="subsections">.
2654 When it appears in the <file>debian/control</file> file,
2655 it gives the value for the subfield of the same name in
2656 the <tt>Files</tt> field of the <file>.changes</file> file.
2657 It also gives the default for the same field in the binary
2662 <sect1 id="f-Priority">
2663 <heading><tt>Priority</tt></heading>
2666 This field represents how important that it is that the user
2667 have the package installed. See <ref id="priorities">.
2671 When it appears in the <file>debian/control</file> file,
2672 it gives the value for the subfield of the same name in
2673 the <tt>Files</tt> field of the <file>.changes</file> file.
2674 It also gives the default for the same field in the binary
2679 <sect1 id="f-Package">
2680 <heading><tt>Package</tt></heading>
2683 The name of the binary package.
2687 Package names must consist only of lower case letters
2688 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2689 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2690 They must be at least two characters long and must start
2691 with an alphanumeric character.
2695 <sect1 id="f-Architecture">
2696 <heading><tt>Architecture</tt></heading>
2699 Depending on context and the control file used, the
2700 <tt>Architecture</tt> field can include the following sets of
2703 <item>A unique single word identifying a Debian machine
2704 architecture, see <ref id="arch-spec">.
2705 <item><tt>all</tt>, which indicates an
2706 architecture-independent package.
2707 <item><tt>any</tt>, which indicates a package available
2708 for building on any architecture.
2709 <item><tt>source</tt>, which indicates a source package.
2714 In the main <file>debian/control</file> file in the source
2715 package, or in the source package control file
2716 <file>.dsc</file>, one may specify a list of architectures
2717 separated by spaces, or the special values <tt>any</tt> or
2722 Specifying <tt>any</tt> indicates that the source package
2723 isn't dependent on any particular architecture and should
2724 compile fine on any one. The produced binary package(s)
2725 will be specific to whatever the current build architecture
2727 This is the most often used setting, and is recommended
2728 for new packages that aren't <tt>Architecture: all</tt>.
2733 Specifying a list of architectures indicates that the source
2734 will build an architecture-dependent package, and will only
2735 work correctly on the listed architectures.<footnote>
2736 This is a setting used for a minority of cases where the
2737 program is not portable. Generally, it should not be used
2743 In a <file>.changes</file> file, the <tt>Architecture</tt>
2744 field lists the architecture(s) of the package(s)
2745 currently being uploaded. This will be a list; if the
2746 source for the package is also being uploaded, the special
2747 entry <tt>source</tt> is also present.
2751 See <ref id="debianrules"> for information how to get the
2752 architecture for the build process.
2756 <sect1 id="f-Essential">
2757 <heading><tt>Essential</tt></heading>
2760 This is a boolean field which may occur only in the
2761 control file of a binary package or in a per-package fields
2762 paragraph of a main source control data file.
2766 If set to <tt>yes</tt> then the package management system
2767 will refuse to remove the package (upgrading and replacing
2768 it is still possible). The other possible value is <tt>no</tt>,
2769 which is the same as not having the field at all.
2774 <heading>Package interrelationship fields:
2775 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2776 <tt>Recommends</tt>, <tt>Suggests</tt>,
2777 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2778 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2782 These fields describe the package's relationships with
2783 other packages. Their syntax and semantics are described
2784 in <ref id="relationships">.</p>
2787 <sect1 id="f-Standards-Version">
2788 <heading><tt>Standards-Version</tt></heading>
2791 The most recent version of the standards (the policy
2792 manual and associated texts) with which the package
2797 The version number has four components: major and minor
2798 version number and major and minor patch level. When the
2799 standards change in a way that requires every package to
2800 change the major number will be changed. Significant
2801 changes that will require work in many packages will be
2802 signaled by a change to the minor number. The major patch
2803 level will be changed for any change to the meaning of the
2804 standards, however small; the minor patch level will be
2805 changed when only cosmetic, typographical or other edits
2806 are made which neither change the meaning of the document
2807 nor affect the contents of packages.
2811 Thus only the first three components of the policy version
2812 are significant in the <em>Standards-Version</em> control
2813 field, and so either these three components or the all
2814 four components may be specified.<footnote>
2815 In the past, people specified the full version number
2816 in the Standards-Version field, for example "2.3.0.0".
2817 Since minor patch-level changes don't introduce new
2818 policy, it was thought it would be better to relax
2819 policy and only require the first 3 components to be
2820 specified, in this example "2.3.0". All four
2821 components may still be used if someone wishes to do so.
2827 <sect1 id="f-Version">
2828 <heading><tt>Version</tt></heading>
2831 The version number of a package. The format is:
2832 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2836 The three components here are:
2838 <tag><var>epoch</var></tag>
2841 This is a single (generally small) unsigned integer. It
2842 may be omitted, in which case zero is assumed. If it is
2843 omitted then the <var>upstream_version</var> may not
2848 It is provided to allow mistakes in the version numbers
2849 of older versions of a package, and also a package's
2850 previous version numbering schemes, to be left behind.
2854 <tag><var>upstream_version</var></tag>
2857 This is the main part of the version number. It is
2858 usually the version number of the original ("upstream")
2859 package from which the <file>.deb</file> file has been made,
2860 if this is applicable. Usually this will be in the same
2861 format as that specified by the upstream author(s);
2862 however, it may need to be reformatted to fit into the
2863 package management system's format and comparison
2868 The comparison behavior of the package management system
2869 with respect to the <var>upstream_version</var> is
2870 described below. The <var>upstream_version</var>
2871 portion of the version number is mandatory.
2875 The <var>upstream_version</var> may contain only
2876 alphanumerics<footnote>
2877 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2879 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2880 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2881 tilde) and should start with a digit. If there is no
2882 <var>debian_revision</var> then hyphens are not allowed;
2883 if there is no <var>epoch</var> then colons are not
2888 <tag><var>debian_revision</var></tag>
2891 This part of the version number specifies the version of
2892 the Debian package based on the upstream version. It
2893 may contain only alphanumerics and the characters
2894 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2895 tilde) and is compared in the same way as the
2896 <var>upstream_version</var> is.
2900 It is optional; if it isn't present then the
2901 <var>upstream_version</var> may not contain a hyphen.
2902 This format represents the case where a piece of
2903 software was written specifically to be turned into a
2904 Debian package, and so there is only one "debianisation"
2905 of it and therefore no revision indication is required.
2909 It is conventional to restart the
2910 <var>debian_revision</var> at <tt>1</tt> each time the
2911 <var>upstream_version</var> is increased.
2915 The package management system will break the version
2916 number apart at the last hyphen in the string (if there
2917 is one) to determine the <var>upstream_version</var> and
2918 <var>debian_revision</var>. The absence of a
2919 <var>debian_revision</var> is equivalent to a
2920 <var>debian_revision</var> of <tt>0</tt>.
2927 When comparing two version numbers, first the <var>epoch</var>
2928 of each are compared, then the <var>upstream_version</var> if
2929 <var>epoch</var> is equal, and then <var>debian_revision</var>
2930 if <var>upstream_version</var> is also equal.
2931 <var>epoch</var> is compared numerically. The
2932 <var>upstream_version</var> and <var>debian_revision</var>
2933 parts are compared by the package management system using the
2934 following algorithm:
2938 The strings are compared from left to right.
2942 First the initial part of each string consisting entirely of
2943 non-digit characters is determined. These two parts (one of
2944 which may be empty) are compared lexically. If a difference
2945 is found it is returned. The lexical comparison is a
2946 comparison of ASCII values modified so that all the letters
2947 sort earlier than all the non-letters and so that a tilde
2948 sorts before anything, even the end of a part. For example,
2949 the following parts are in sorted order from earliest to
2950 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
2951 <tt>a</tt>.<footnote>
2952 One common use of <tt>~</tt> is for upstream pre-releases.
2953 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
2954 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
2959 Then the initial part of the remainder of each string which
2960 consists entirely of digit characters is determined. The
2961 numerical values of these two parts are compared, and any
2962 difference found is returned as the result of the comparison.
2963 For these purposes an empty string (which can only occur at
2964 the end of one or both version strings being compared) counts
2969 These two steps (comparing and removing initial non-digit
2970 strings and initial digit strings) are repeated until a
2971 difference is found or both strings are exhausted.
2975 Note that the purpose of epochs is to allow us to leave behind
2976 mistakes in version numbering, and to cope with situations
2977 where the version numbering scheme changes. It is
2978 <em>not</em> intended to cope with version numbers containing
2979 strings of letters which the package management system cannot
2980 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2981 silly orderings (the author of this manual has heard of a
2982 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2983 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2984 <tt>2</tt> and so forth).
2988 <sect1 id="f-Description">
2989 <heading><tt>Description</tt></heading>
2992 In a source or binary control file, the <tt>Description</tt>
2993 field contains a description of the binary package, consisting
2994 of two parts, the synopsis or the short description, and the
2995 long description. The field's format is as follows:
3000 Description: <single line synopsis>
3001 <extended description over several lines>
3006 The lines in the extended description can have these formats:
3012 Those starting with a single space are part of a paragraph.
3013 Successive lines of this form will be word-wrapped when
3014 displayed. The leading space will usually be stripped off.
3018 Those starting with two or more spaces. These will be
3019 displayed verbatim. If the display cannot be panned
3020 horizontally, the displaying program will line wrap them "hard"
3021 (i.e., without taking account of word breaks). If it can they
3022 will be allowed to trail off to the right. None, one or two
3023 initial spaces may be deleted, but the number of spaces
3024 deleted from each line will be the same (so that you can have
3025 indenting work correctly, for example).
3029 Those containing a single space followed by a single full stop
3030 character. These are rendered as blank lines. This is the
3031 <em>only</em> way to get a blank line<footnote>
3032 Completely empty lines will not be rendered as blank lines.
3033 Instead, they will cause the parser to think you're starting
3034 a whole new record in the control file, and will therefore
3035 likely abort with an error.
3040 Those containing a space, a full stop and some more characters.
3041 These are for future expansion. Do not use them.
3047 Do not use tab characters. Their effect is not predictable.
3051 See <ref id="descriptions"> for further information on this.
3055 In a <file>.changes</file> file, the <tt>Description</tt> field
3056 contains a summary of the descriptions for the packages being
3061 The part of the field before the first newline is empty;
3062 thereafter each line has the name of a binary package and
3063 the summary description line from that binary package.
3064 Each line is indented by one space.
3069 <sect1 id="f-Distribution">
3070 <heading><tt>Distribution</tt></heading>
3073 In a <file>.changes</file> file or parsed changelog output
3074 this contains the (space-separated) name(s) of the
3075 distribution(s) where this version of the package should
3076 be installed. Valid distributions are determined by the
3077 archive maintainers.<footnote>
3078 Current distribution names in the Debian archive used in
3079 <file>.changes</file> files are:
3080 <taglist compact="compact">
3081 <tag><em>unstable</em></tag>
3083 This distribution value refers to the
3084 <em>developmental</em> part of the Debian distribution
3085 tree. Most new packages, new upstream versions of
3086 packages and bug fixes go into the <em>unstable</em>
3090 <tag><em>experimental</em></tag>
3092 The packages with this distribution value are deemed
3093 by their maintainers to be high risk. Oftentimes they
3094 represent early beta or developmental packages from
3095 various sources that the maintainers want people to
3096 try, but are not ready to be a part of the other parts
3097 of the Debian distribution tree.
3100 <tag><em>stable-proposed-updates</em></tag>
3102 Once a distribution of Debian GNU/Linux is released,
3103 it is declared <em>stable</em> and only security fixes
3104 and other major bug fixes are allowed. Proposed
3105 non-security updates for <em>stable</em> are uploaded
3106 using this distribution value after getting approval
3107 from the stable release managers.
3110 <tag><em>testing-proposed-updates</em></tag>
3112 The <em>testing</em> distribution normally receives
3113 its packages via the <em>unstable</em> distribution
3114 after a short time lag. However sometimes, such as
3115 during release freezes before a new stable release or
3116 when a problem in the <em>testing</em> distribution
3117 requires fixing before the <em>unstable</em> version
3118 can migrate, direct updates to a package in
3119 <em>testing</em> are useful. This distribution value
3120 is used for those exceptions, after approval from the
3126 Security fixes for the <em>stable</em> or
3127 <em>testing</em> distributions are handled via a
3128 separate upload queue and special
3129 <em>stable-security</em> and <em>testing-security<em>
3130 distribution values.
3134 More information is available in the Debian Developer's
3135 Reference, section "The Debian archive".
3138 The Debian archive software only supports listing a single
3139 distribution. Migration of packages to other distributions is
3140 handled outside of the upload process.
3145 <heading><tt>Date</tt></heading>
3148 This field includes the date the package was built or last edited.
3152 The value of this field is usually extracted from the
3153 <file>debian/changelog</file> file - see
3154 <ref id="dpkgchangelog">).
3158 <sect1 id="f-Format">
3159 <heading><tt>Format</tt></heading>
3162 This field specifies a format revision for the file.
3163 The most current format described in the Policy Manual
3164 is version <strong>1.5</strong>. The syntax of the
3165 format value is the same as that of a package version
3166 number except that no epoch or Debian revision is allowed
3167 - see <ref id="f-Version">.
3171 <sect1 id="f-Urgency">
3172 <heading><tt>Urgency</tt></heading>
3175 This is a description of how important it is to upgrade to
3176 this version from previous ones. It consists of a single
3177 keyword taking one of the values <tt>low</tt>,
3178 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3179 <tt>critical</tt><footnote>
3180 Other urgency values are supported with configuration
3181 changes in the archive software but are not used in Debian.
3182 The urgency affects how quickly a package will be considered
3183 for inclusion into the <tt>testing</tt> distribution and
3184 gives an indication of the importance of any fixes included
3185 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3186 treated as synonymous.
3187 </footnote> (not case-sensitive) followed by an optional
3188 commentary (separated by a space) which is usually in
3189 parentheses. For example:
3192 Urgency: low (HIGH for users of diversions)
3198 The value of this field is usually extracted from the
3199 <file>debian/changelog</file> file - see
3200 <ref id="dpkgchangelog">.
3204 <sect1 id="f-Changes">
3205 <heading><tt>Changes</tt></heading>
3208 This field contains the human-readable changes data, describing
3209 the differences between the last version and the current one.
3213 There should be nothing in this field before the first
3214 newline; all the subsequent lines must be indented by at
3215 least one space; blank lines must be represented by a line
3216 consisting only of a space and a full stop.
3220 The value of this field is usually extracted from the
3221 <file>debian/changelog</file> file - see
3222 <ref id="dpkgchangelog">).
3226 Each version's change information should be preceded by a
3227 "title" line giving at least the version, distribution(s)
3228 and urgency, in a human-readable way.
3232 If data from several versions is being returned the entry
3233 for the most recent version should be returned first, and
3234 entries should be separated by the representation of a
3235 blank line (the "title" line may also be followed by the
3236 representation of blank line).
3240 <sect1 id="f-Binary">
3241 <heading><tt>Binary</tt></heading>
3244 This field is a list of binary packages.
3248 When it appears in the <file>.dsc</file> file it is the list
3249 of binary packages which a source package can produce. It
3250 does not necessarily produce all of these binary packages
3251 for every architecture. The source control file doesn't
3252 contain details of which architectures are appropriate for
3253 which of the binary packages.
3257 When it appears in a <file>.changes</file> file it lists the
3258 names of the binary packages actually being uploaded.
3262 The syntax is a list of binary packages separated by
3264 A space after each comma is conventional.
3265 </footnote>. Currently the packages must be separated using
3266 only spaces in the <file>.changes</file> file.
3270 <sect1 id="f-Installed-Size">
3271 <heading><tt>Installed-Size</tt></heading>
3274 This field appears in the control files of binary
3275 packages, and in the <file>Packages</file> files. It gives
3276 the total amount of disk space required to install the
3281 The disk space is represented in kilobytes as a simple
3286 <sect1 id="f-Files">
3287 <heading><tt>Files</tt></heading>
3290 This field contains a list of files with information about
3291 each one. The exact information and syntax varies with
3292 the context. In all cases the part of the field
3293 contents on the same line as the field name is empty. The
3294 remainder of the field is one line per file, each line
3295 being indented by one space and containing a number of
3296 sub-fields separated by spaces.
3300 In the <file>.dsc</file> file, each line contains the MD5
3301 checksum, size and filename of the tar file and (if applicable)
3302 diff file which make up the remainder of the source
3304 That is, the parts which are not the <tt>.dsc</tt>.
3306 The exact forms of the filenames are described
3307 in <ref id="pkg-sourcearchives">.
3311 In the <file>.changes</file> file this contains one line per
3312 file being uploaded. Each line contains the MD5 checksum,
3313 size, section and priority and the filename.
3314 The <qref id="f-Section">section</qref>
3315 and <qref id="f-Priority">priority</qref>
3316 are the values of the corresponding fields in
3317 the main source control file. If no section or priority is
3318 specified then <tt>-</tt> should be used, though section
3319 and priority values must be specified for new packages to
3320 be installed properly.
3324 The special value <tt>byhand</tt> for the section in a
3325 <tt>.changes</tt> file indicates that the file in question
3326 is not an ordinary package file and must by installed by
3327 hand by the distribution maintainers. If the section is
3328 <tt>byhand</tt> the priority should be <tt>-</tt>.
3332 If a new Debian revision of a package is being shipped and
3333 no new original source archive is being distributed the
3334 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3335 entry for the original source archive
3336 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3337 but the <file>.changes</file> file should leave it out. In
3338 this case the original source archive on the distribution
3339 site must match exactly, byte-for-byte, the original
3340 source archive which was used to generate the
3341 <file>.dsc</file> file and diff which are being uploaded.</p>
3344 <sect1 id="f-Closes">
3345 <heading><tt>Closes</tt></heading>
3348 A space-separated list of bug report numbers that the upload
3349 governed by the .changes file closes.
3353 <sect1 id="f-Homepage">
3354 <heading><tt>Homepage</tt></heading>
3357 The URL of the web site for this package, preferably (when
3358 applicable) the site from which the original source can be
3359 obtained and any additional upstream documentation or
3360 information may be found. The content of this field is a
3361 simple URL without any surrounding characters such as
3369 <heading>User-defined fields</heading>
3372 Additional user-defined fields may be added to the
3373 source package control file. Such fields will be
3374 ignored, and not copied to (for example) binary or
3375 source package control files or upload control files.
3379 If you wish to add additional unsupported fields to
3380 these output files you should use the mechanism
3385 Fields in the main source control information file with
3386 names starting <tt>X</tt>, followed by one or more of
3387 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3388 be copied to the output files. Only the part of the
3389 field name after the hyphen will be used in the output
3390 file. Where the letter <tt>B</tt> is used the field
3391 will appear in binary package control files, where the
3392 letter <tt>S</tt> is used in source package control
3393 files and where <tt>C</tt> is used in upload control
3394 (<tt>.changes</tt>) files.
3398 For example, if the main source information control file
3401 XBS-Comment: I stand between the candle and the star.
3403 then the binary and source package control files will contain the
3406 Comment: I stand between the candle and the star.
3415 <chapt id="maintainerscripts">
3416 <heading>Package maintainer scripts and installation procedure</heading>
3419 <heading>Introduction to package maintainer scripts</heading>
3422 It is possible to supply scripts as part of a package which
3423 the package management system will run for you when your
3424 package is installed, upgraded or removed.
3428 These scripts are the files <prgn>preinst</prgn>,
3429 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3430 <prgn>postrm</prgn> in the control area of the package.
3431 They must be proper executable files; if they are scripts
3432 (which is recommended), they must start with the usual
3433 <tt>#!</tt> convention. They should be readable and
3434 executable by anyone, and must not be world-writable.
3438 The package management system looks at the exit status from
3439 these scripts. It is important that they exit with a
3440 non-zero status if there is an error, so that the package
3441 management system can stop its processing. For shell
3442 scripts this means that you <em>almost always</em> need to
3443 use <tt>set -e</tt> (this is usually true when writing shell
3444 scripts, in fact). It is also important, of course, that
3445 they exit with a zero status if everything went well.
3449 Additionally, packages interacting with users using
3450 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3451 install a <prgn>config</prgn> script in the control area,
3452 see <ref id="maintscriptprompt"> for details.
3456 When a package is upgraded a combination of the scripts from
3457 the old and new packages is called during the upgrade
3458 procedure. If your scripts are going to be at all
3459 complicated you need to be aware of this, and may need to
3460 check the arguments to your scripts.
3464 Broadly speaking the <prgn>preinst</prgn> is called before
3465 (a particular version of) a package is installed, and the
3466 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3467 before (a version of) a package is removed and the
3468 <prgn>postrm</prgn> afterwards.
3472 Programs called from maintainer scripts should not normally
3473 have a path prepended to them. Before installation is
3474 started, the package management system checks to see if the
3475 programs <prgn>ldconfig</prgn>,
3476 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3477 and <prgn>update-rc.d</prgn> can be found via the
3478 <tt>PATH</tt> environment variable. Those programs, and any
3479 other program that one would expect to be in the
3480 <tt>PATH</tt>, should thus be invoked without an absolute
3481 pathname. Maintainer scripts should also not reset the
3482 <tt>PATH</tt>, though they might choose to modify it by
3483 prepending or appending package-specific directories. These
3484 considerations really apply to all shell scripts.</p>
3487 <sect id="idempotency">
3488 <heading>Maintainer scripts idempotency</heading>
3491 It is necessary for the error recovery procedures that the
3492 scripts be idempotent. This means that if it is run
3493 successfully, and then it is called again, it doesn't bomb
3494 out or cause any harm, but just ensures that everything is
3495 the way it ought to be. If the first call failed, or
3496 aborted half way through for some reason, the second call
3497 should merely do the things that were left undone the first
3498 time, if any, and exit with a success status if everything
3500 This is so that if an error occurs, the user interrupts
3501 <prgn>dpkg</prgn> or some other unforeseen circumstance
3502 happens you don't leave the user with a badly-broken
3503 package when <prgn>dpkg</prgn> attempts to repeat the
3509 <sect id="controllingterminal">
3510 <heading>Controlling terminal for maintainer scripts</heading>
3513 The maintainer scripts are guaranteed to run with a
3514 controlling terminal and can interact with the user.
3515 Because these scripts may be executed with standard output
3516 redirected into a pipe for logging purposes, Perl scripts
3517 should set unbuffered output by setting <tt>$|=1</tt> so
3518 that the output is printed immediately rather than being
3522 <sect id="exitstatus">
3523 <heading>Exit status</heading>
3526 Each script must return a zero exit status for
3527 success, or a nonzero one for failure, since the package
3528 management system looks for the exit status of these scripts
3529 and determines what action to take next based on that datum.
3533 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3538 <list compact="compact">
3540 <var>new-preinst</var> <tt>install</tt>
3543 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3546 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3549 <var>old-preinst</var> <tt>abort-upgrade</tt>
3550 <var>new-version</var>
3555 <list compact="compact">
3557 <var>postinst</var> <tt>configure</tt>
3558 <var>most-recently-configured-version</var>
3561 <var>old-postinst</var> <tt>abort-upgrade</tt>
3562 <var>new-version</var>
3565 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3566 <tt>in-favour</tt> <var>package</var>
3567 <var>new-version</var>
3570 <var>postinst</var> <tt>abort-remove</tt>
3573 <var>deconfigured's-postinst</var>
3574 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3575 <var>failed-install-package</var> <var>version</var>
3576 [<tt>removing</tt> <var>conflicting-package</var>
3582 <list compact="compact">
3584 <var>prerm</var> <tt>remove</tt>
3587 <var>old-prerm</var> <tt>upgrade</tt>
3588 <var>new-version</var>
3591 <var>new-prerm</var> <tt>failed-upgrade</tt>
3592 <var>old-version</var>
3595 <var>conflictor's-prerm</var> <tt>remove</tt>
3596 <tt>in-favour</tt> <var>package</var>
3597 <var>new-version</var>
3600 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3601 <tt>in-favour</tt> <var>package-being-installed</var>
3602 <var>version</var> [<tt>removing</tt>
3603 <var>conflicting-package</var>
3609 <list compact="compact">
3611 <var>postrm</var> <tt>remove</tt>
3614 <var>postrm</var> <tt>purge</tt>
3617 <var>old-postrm</var> <tt>upgrade</tt>
3618 <var>new-version</var>
3621 <var>new-postrm</var> <tt>failed-upgrade</tt>
3622 <var>old-version</var>
3625 <var>new-postrm</var> <tt>abort-install</tt>
3628 <var>new-postrm</var> <tt>abort-install</tt>
3629 <var>old-version</var>
3632 <var>new-postrm</var> <tt>abort-upgrade</tt>
3633 <var>old-version</var>
3636 <var>disappearer's-postrm</var> <tt>disappear</tt>
3637 <var>overwriter</var>
3638 <var>overwriter-version</var>
3644 <sect id="unpackphase">
3645 <heading>Details of unpack phase of installation or upgrade</heading>
3648 The procedure on installation/upgrade/overwrite/disappear
3649 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3650 stage of <tt>dpkg --install</tt>) is as follows. In each
3651 case, if a major error occurs (unless listed below) the
3652 actions are, in general, run backwards - this means that the
3653 maintainer scripts are run with different arguments in
3654 reverse order. These are the "error unwind" calls listed
3661 If a version of the package is already installed, call
3662 <example compact="compact">
3663 <var>old-prerm</var> upgrade <var>new-version</var>
3667 If the script runs but exits with a non-zero
3668 exit status, <prgn>dpkg</prgn> will attempt:
3669 <example compact="compact">
3670 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3672 If this works, the upgrade continues. If this
3673 does not work, the error unwind:
3674 <example compact="compact">
3675 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3677 If this works, then the old-version is
3678 "Installed", if not, the old version is in a
3679 "Failed-Config" state.
3685 If a "conflicting" package is being removed at the same time,
3686 or if any package will be broken (due to <tt>Breaks</tt>):
3689 If <tt>--auto-deconfigure</tt> is
3690 specified, call, for each package to be deconfigured
3691 due to <tt>Breaks</tt>:
3692 <example compact="compact">
3693 <var>deconfigured's-prerm</var> deconfigure \
3694 in-favour <var>package-being-installed</var> <var>version</var>
3697 <example compact="compact">
3698 <var>deconfigured's-postinst</var> abort-deconfigure \
3699 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3701 The deconfigured packages are marked as
3702 requiring configuration, so that if
3703 <tt>--install</tt> is used they will be
3704 configured again if possible.
3707 If any packages depended on a conflicting
3708 package being removed and <tt>--auto-deconfigure</tt> is
3709 specified, call, for each such package:
3710 <example compact="compact">
3711 <var>deconfigured's-prerm</var> deconfigure \
3712 in-favour <var>package-being-installed</var> <var>version</var> \
3713 removing <var>conflicting-package</var> <var>version</var>
3716 <example compact="compact">
3717 <var>deconfigured's-postinst</var> abort-deconfigure \
3718 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3719 removing <var>conflicting-package</var> <var>version</var>
3721 The deconfigured packages are marked as
3722 requiring configuration, so that if
3723 <tt>--install</tt> is used they will be
3724 configured again if possible.
3727 To prepare for removal of each conflicting package, call:
3728 <example compact="compact">
3729 <var>conflictor's-prerm</var> remove \
3730 in-favour <var>package</var> <var>new-version</var>
3733 <example compact="compact">
3734 <var>conflictor's-postinst</var> abort-remove \
3735 in-favour <var>package</var> <var>new-version</var>
3744 If the package is being upgraded, call:
3745 <example compact="compact">
3746 <var>new-preinst</var> upgrade <var>old-version</var>
3748 If this fails, we call:
3750 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3757 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3759 is called. If this works, then the old version
3760 is in an "Installed" state, or else it is left
3761 in an "Unpacked" state.
3766 If it fails, then the old version is left
3767 in an "Half-Installed" state.
3774 Otherwise, if the package had some configuration
3775 files from a previous version installed (i.e., it
3776 is in the "configuration files only" state):
3777 <example compact="compact">
3778 <var>new-preinst</var> install <var>old-version</var>
3782 <var>new-postrm</var> abort-install <var>old-version</var>
3784 If this fails, the package is left in a
3785 "Half-Installed" state, which requires a
3786 reinstall. If it works, the packages is left in
3787 a "Config Files" state.
3790 Otherwise (i.e., the package was completely purged):
3791 <example compact="compact">
3792 <var>new-preinst</var> install
3795 <example compact="compact">
3796 <var>new-postrm</var> abort-install
3798 If the error-unwind fails, the package is in a
3799 "Half Installed" phase, and requires a
3800 reinstall. If the error unwind works, the
3801 package is in a not installed state.
3808 The new package's files are unpacked, overwriting any
3809 that may be on the system already, for example any
3810 from the old version of the same package or from
3811 another package. Backups of the old files are kept
3812 temporarily, and if anything goes wrong the package
3813 management system will attempt to put them back as
3814 part of the error unwind.
3818 It is an error for a package to contain files which
3819 are on the system in another package, unless
3820 <tt>Replaces</tt> is used (see <ref id="replaces">).
3822 The following paragraph is not currently the case:
3823 Currently the <tt>- - force-overwrite</tt> flag is
3824 enabled, downgrading it to a warning, but this may not
3830 It is a more serious error for a package to contain a
3831 plain file or other kind of non-directory where another
3832 package has a directory (again, unless
3833 <tt>Replaces</tt> is used). This error can be
3834 overridden if desired using
3835 <tt>--force-overwrite-dir</tt>, but this is not
3840 Packages which overwrite each other's files produce
3841 behavior which, though deterministic, is hard for the
3842 system administrator to understand. It can easily
3843 lead to "missing" programs if, for example, a package
3844 is installed which overwrites a file from another
3845 package, and is then removed again.<footnote>
3846 Part of the problem is due to what is arguably a
3847 bug in <prgn>dpkg</prgn>.
3852 A directory will never be replaced by a symbolic link
3853 to a directory or vice versa; instead, the existing
3854 state (symlink or not) will be left alone and
3855 <prgn>dpkg</prgn> will follow the symlink if there is
3864 If the package is being upgraded, call
3865 <example compact="compact">
3866 <var>old-postrm</var> upgrade <var>new-version</var>
3870 If this fails, <prgn>dpkg</prgn> will attempt:
3871 <example compact="compact">
3872 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3874 If this works, installation continues. If not,
3876 <example compact="compact">
3877 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3879 If this fails, the old version is left in an
3880 "Half Installed" state. If it works, dpkg now
3882 <example compact="compact">
3883 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3885 If this fails, the old version is left in an
3886 "Half Installed" state. If it works, dpkg now
3888 <example compact="compact">
3889 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3891 If this fails, the old version is in an
3898 This is the point of no return - if
3899 <prgn>dpkg</prgn> gets this far, it won't back off
3900 past this point if an error occurs. This will
3901 leave the package in a fairly bad state, which
3902 will require a successful re-installation to clear
3903 up, but it's when <prgn>dpkg</prgn> starts doing
3904 things that are irreversible.
3909 Any files which were in the old version of the package
3910 but not in the new are removed.
3914 The new file list replaces the old.
3918 The new maintainer scripts replace the old.
3922 Any packages all of whose files have been overwritten
3923 during the installation, and which aren't required for
3924 dependencies, are considered to have been removed.
3925 For each such package
3928 <prgn>dpkg</prgn> calls:
3929 <example compact="compact">
3930 <var>disappearer's-postrm</var> disappear \
3931 <var>overwriter</var> <var>overwriter-version</var>
3935 The package's maintainer scripts are removed.
3938 It is noted in the status database as being in a
3939 sane state, namely not installed (any conffiles
3940 it may have are ignored, rather than being
3941 removed by <prgn>dpkg</prgn>). Note that
3942 disappearing packages do not have their prerm
3943 called, because <prgn>dpkg</prgn> doesn't know
3944 in advance that the package is going to
3951 Any files in the package we're unpacking that are also
3952 listed in the file lists of other packages are removed
3953 from those lists. (This will lobotomize the file list
3954 of the "conflicting" package if there is one.)
3958 The backup files made during installation, above, are
3964 The new package's status is now sane, and recorded as
3969 Here is another point of no return - if the
3970 conflicting package's removal fails we do not unwind
3971 the rest of the installation; the conflicting package
3972 is left in a half-removed limbo.
3977 If there was a conflicting package we go and do the
3978 removal actions (described below), starting with the
3979 removal of the conflicting package's files (any that
3980 are also in the package being installed have already
3981 been removed from the conflicting package's file list,
3982 and so do not get removed now).
3988 <sect id="configdetails"><heading>Details of configuration</heading>
3991 When we configure a package (this happens with <tt>dpkg
3992 --install</tt> and <tt>dpkg --configure</tt>), we first
3993 update any <tt>conffile</tt>s and then call:
3994 <example compact="compact">
3995 <var>postinst</var> configure <var>most-recently-configured-version</var>
4000 No attempt is made to unwind after errors during
4001 configuration. If the configuration fails, the package is in
4002 a "Failed Config" state, and an error message is generated.
4006 If there is no most recently configured version
4007 <prgn>dpkg</prgn> will pass a null argument.
4010 Historical note: Truly ancient (pre-1997) versions of
4011 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4012 (including the angle brackets) in this case. Even older
4013 ones did not pass a second argument at all, under any
4014 circumstance. Note that upgrades using such an old dpkg
4015 version are unlikely to work for other reasons, even if
4016 this old argument behavior is handled by your postinst script.
4022 <sect id="removedetails"><heading>Details of removal and/or
4023 configuration purging</heading>
4029 <example compact="compact">
4030 <var>prerm</var> remove
4034 If prerm fails during replacement due to conflict
4036 <var>conflictor's-postinst</var> abort-remove \
4037 in-favour <var>package</var> <var>new-version</var>
4041 <var>postinst</var> abort-remove
4045 If this fails, the package is in a "Failed-Config"
4046 state, or else it remains "Installed".
4050 The package's files are removed (except <tt>conffile</tt>s).
4053 <example compact="compact">
4054 <var>postrm</var> remove
4058 If it fails, there's no error unwind, and the package is in
4059 an "Half-Installed" state.
4064 All the maintainer scripts except the <prgn>postrm</prgn>
4069 If we aren't purging the package we stop here. Note
4070 that packages which have no <prgn>postrm</prgn> and no
4071 <tt>conffile</tt>s are automatically purged when
4072 removed, as there is no difference except for the
4073 <prgn>dpkg</prgn> status.
4077 The <tt>conffile</tt>s and any backup files
4078 (<tt>~</tt>-files, <tt>#*#</tt> files,
4079 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4084 <example compact="compact">
4085 <var>postrm</var> purge
4089 If this fails, the package remains in a "Config-Files"
4094 The package's file list is removed.
4103 <chapt id="relationships">
4104 <heading>Declaring relationships between packages</heading>
4106 <sect id="depsyntax">
4107 <heading>Syntax of relationship fields</heading>
4110 These fields all have a uniform syntax. They are a list of
4111 package names separated by commas.
4115 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4116 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4117 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4118 control file fields of the package, which declare
4119 dependencies on other packages, the package names listed may
4120 also include lists of alternative package names, separated
4121 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4122 if any one of the alternative packages is installed, that
4123 part of the dependency is considered to be satisfied.
4127 All of the fields except for <tt>Provides</tt> may restrict
4128 their applicability to particular versions of each named
4129 package. This is done in parentheses after each individual
4130 package name; the parentheses should contain a relation from
4131 the list below followed by a version number, in the format
4132 described in <ref id="f-Version">.
4136 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4137 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4138 strictly earlier, earlier or equal, exactly equal, later or
4139 equal and strictly later, respectively. The deprecated
4140 forms <tt><</tt> and <tt>></tt> were used to mean
4141 earlier/later or equal, rather than strictly earlier/later,
4142 so they should not appear in new packages (though
4143 <prgn>dpkg</prgn> still supports them).
4147 Whitespace may appear at any point in the version
4148 specification subject to the rules in <ref
4149 id="controlsyntax">, and must appear where it's necessary to
4150 disambiguate; it is not otherwise significant. All of the
4151 relationship fields may span multiple lines. For
4152 consistency and in case of future changes to
4153 <prgn>dpkg</prgn> it is recommended that a single space be
4154 used after a version relationship and before a version
4155 number; it is also conventional to put a single space after
4156 each comma, on either side of each vertical bar, and before
4157 each open parenthesis. When wrapping a relationship field, it
4158 is conventional to do so after a comma and before the space
4159 following that comma.
4163 For example, a list of dependencies might appear as:
4164 <example compact="compact">
4167 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4172 All fields that specify build-time relationships
4173 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4174 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4175 may be restricted to a certain set of architectures. This
4176 is indicated in brackets after each individual package name and
4177 the optional version specification. The brackets enclose a
4178 list of Debian architecture names separated by whitespace.
4179 Exclamation marks may be prepended to each of the names.
4180 (It is not permitted for some names to be prepended with
4181 exclamation marks while others aren't.) If the current Debian
4182 host architecture is not in this list and there are no
4183 exclamation marks in the list, or it is in the list with a
4184 prepended exclamation mark, the package name and the
4185 associated version specification are ignored completely for
4186 the purposes of defining the relationships.
4191 <example compact="compact">
4193 Build-Depends-Indep: texinfo
4194 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4195 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4197 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4198 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4199 <tt>gnumach-dev</tt> only on hurd-i386.
4203 If the architecture-restricted dependency is part of a set of
4204 alternatives using <tt>|</tt>, that alternative is ignored
4205 completely on architectures that do not match the restriction.
4207 <example compact="compact">
4208 Build-Depends: foo [!i386] | bar [!amd64]
4210 is equivalent to <tt>bar</tt> on the i386 architecture, to
4211 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4212 bar</tt> on all other architectures.
4216 Note that the binary package relationship fields such as
4217 <tt>Depends</tt> appear in one of the binary package
4218 sections of the control file, whereas the build-time
4219 relationships such as <tt>Build-Depends</tt> appear in the
4220 source package section of the control file (which is the
4225 <sect id="binarydeps">
4226 <heading>Binary Dependencies - <tt>Depends</tt>,
4227 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4228 <tt>Pre-Depends</tt>
4232 Packages can declare in their control file that they have
4233 certain relationships to other packages - for example, that
4234 they may not be installed at the same time as certain other
4235 packages, and/or that they depend on the presence of others.
4239 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4240 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4241 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4245 These seven fields are used to declare a dependency
4246 relationship by one package on another. Except for
4247 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4248 depending (binary) package's control file.
4249 (<tt>Enhances</tt> appears in the recommending package's
4250 control file, and <tt>Breaks</tt> appears in the version of
4251 depended-on package which causes the named package to
4256 A <tt>Depends</tt> field takes effect <em>only</em> when a
4257 package is to be configured. It does not prevent a package
4258 being on the system in an unconfigured state while its
4259 dependencies are unsatisfied, and it is possible to replace
4260 a package whose dependencies are satisfied and which is
4261 properly installed with a different version whose
4262 dependencies are not and cannot be satisfied; when this is
4263 done the depending package will be left unconfigured (since
4264 attempts to configure it will give errors) and will not
4265 function properly. If it is necessary, a
4266 <tt>Pre-Depends</tt> field can be used, which has a partial
4267 effect even when a package is being unpacked, as explained
4268 in detail below. (The other three dependency fields,
4269 <tt>Recommends</tt>, <tt>Suggests</tt> and
4270 <tt>Enhances</tt>, are only used by the various front-ends
4271 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4272 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4276 For this reason packages in an installation run are usually
4277 all unpacked first and all configured later; this gives
4278 later versions of packages with dependencies on later
4279 versions of other packages the opportunity to have their
4280 dependencies satisfied.
4284 In case of circular dependencies, since installation or
4285 removal order honoring the dependency order can't be
4286 established, dependency loops are broken at some point
4287 (based on rules below), and some packages may not be able to
4288 rely on their dependencies being present when being
4289 installed or removed, depending on which side of the break
4290 of the circular dependency loop they happen to be on. If one
4291 of the packages in the loop has no postinst script, then the
4292 cycle will be broken at that package, so as to ensure that
4293 all postinst scripts run with the dependencies properly
4294 configured if this is possible. Otherwise the breaking point
4299 The <tt>Depends</tt> field thus allows package maintainers
4300 to impose an order in which packages should be configured.
4304 The meaning of the five dependency fields is as follows:
4306 <tag><tt>Depends</tt></tag>
4309 This declares an absolute dependency. A package will
4310 not be configured unless all of the packages listed in
4311 its <tt>Depends</tt> field have been correctly
4316 The <tt>Depends</tt> field should be used if the
4317 depended-on package is required for the depending
4318 package to provide a significant amount of
4323 The <tt>Depends</tt> field should also be used if the
4324 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4325 <prgn>postrm</prgn> scripts require the package to be
4326 present in order to run. Note, however, that the
4327 <prgn>postrm</prgn> cannot rely on any non-essential
4328 packages to be present during the <tt>purge</tt>
4332 <tag><tt>Recommends</tt></tag>
4335 This declares a strong, but not absolute, dependency.
4339 The <tt>Recommends</tt> field should list packages
4340 that would be found together with this one in all but
4341 unusual installations.
4345 <tag><tt>Suggests</tt></tag>
4347 This is used to declare that one package may be more
4348 useful with one or more others. Using this field
4349 tells the packaging system and the user that the
4350 listed packages are related to this one and can
4351 perhaps enhance its usefulness, but that installing
4352 this one without them is perfectly reasonable.
4355 <tag><tt>Enhances</tt></tag>
4357 This field is similar to Suggests but works in the
4358 opposite direction. It is used to declare that a
4359 package can enhance the functionality of another
4363 <tag><tt>Pre-Depends</tt></tag>
4366 This field is like <tt>Depends</tt>, except that it
4367 also forces <prgn>dpkg</prgn> to complete installation
4368 of the packages named before even starting the
4369 installation of the package which declares the
4370 pre-dependency, as follows:
4374 When a package declaring a pre-dependency is about to
4375 be <em>unpacked</em> the pre-dependency can be
4376 satisfied if the depended-on package is either fully
4377 configured, <em>or even if</em> the depended-on
4378 package(s) are only unpacked or half-configured,
4379 provided that they have been configured correctly at
4380 some point in the past (and not removed or partially
4381 removed since). In this case, both the
4382 previously-configured and currently unpacked or
4383 half-configured versions must satisfy any version
4384 clause in the <tt>Pre-Depends</tt> field.
4388 When the package declaring a pre-dependency is about
4389 to be <em>configured</em>, the pre-dependency will be
4390 treated as a normal <tt>Depends</tt>, that is, it will
4391 be considered satisfied only if the depended-on
4392 package has been correctly configured.
4396 <tt>Pre-Depends</tt> should be used sparingly,
4397 preferably only by packages whose premature upgrade or
4398 installation would hamper the ability of the system to
4399 continue with any upgrade that might be in progress.
4403 <tt>Pre-Depends</tt> are also required if the
4404 <prgn>preinst</prgn> script depends on the named
4405 package. It is best to avoid this situation if
4413 When selecting which level of dependency to use you should
4414 consider how important the depended-on package is to the
4415 functionality of the one declaring the dependency. Some
4416 packages are composed of components of varying degrees of
4417 importance. Such a package should list using
4418 <tt>Depends</tt> the package(s) which are required by the
4419 more important components. The other components'
4420 requirements may be mentioned as Suggestions or
4421 Recommendations, as appropriate to the components' relative
4427 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4430 Using <tt>Breaks</tt> may cause problems for upgrades from older
4431 versions of Debian and should not be used until the stable
4432 release of Debian supports <tt>Breaks</tt>.
4436 When one binary package declares that it breaks another,
4437 <prgn>dpkg</prgn> will refuse to allow the package which
4438 declares <tt>Breaks</tt> be installed unless the broken
4439 package is deconfigured first, and it will refuse to
4440 allow the broken package to be reconfigured.
4444 A package will not be regarded as causing breakage merely
4445 because its configuration files are still installed; it must
4446 be at least half-installed.
4450 A special exception is made for packages which declare that
4451 they break their own package name or a virtual package which
4452 they provide (see below): this does not count as a real
4457 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4458 version clause; such a <tt>Breaks</tt> is introduced in the
4459 version of an (implicit or explicit) dependency which
4460 violates an assumption or reveals a bug in earlier versions
4461 of the broken package. This use of <tt>Breaks</tt> will
4462 inform higher-level package management tools that broken
4463 package must be upgraded before the new one.
4467 If the breaking package also overwrites some files from the
4468 older package, it should use <tt>Replaces</tt> (not
4469 <tt>Conflicts</tt>) to ensure this goes smoothly.
4473 <sect id="conflicts">
4474 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4477 When one binary package declares a conflict with another
4478 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4479 refuse to allow them to be installed on the system at the
4484 If one package is to be installed, the other must be removed
4485 first - if the package being installed is marked as
4486 replacing (see <ref id="replaces">) the one on the system,
4487 or the one on the system is marked as deselected, or both
4488 packages are marked <tt>Essential</tt>, then
4489 <prgn>dpkg</prgn> will automatically remove the package
4490 which is causing the conflict, otherwise it will halt the
4491 installation of the new package with an error. This
4492 mechanism is specifically designed to produce an error when
4493 the installed package is <tt>Essential</tt>, but the new
4498 A package will not cause a conflict merely because its
4499 configuration files are still installed; it must be at least
4504 A special exception is made for packages which declare a
4505 conflict with their own package name, or with a virtual
4506 package which they provide (see below): this does not
4507 prevent their installation, and allows a package to conflict
4508 with others providing a replacement for it. You use this
4509 feature when you want the package in question to be the only
4510 package providing some feature.
4514 A <tt>Conflicts</tt> entry should almost never have an
4515 "earlier than" version clause. This would prevent
4516 <prgn>dpkg</prgn> from upgrading or installing the package
4517 which declared such a conflict until the upgrade or removal
4518 of the conflicted-with package had been completed. Instead,
4519 <tt>Breaks</tt> may be used (once <tt>Breaks</tt> is supported
4520 by the stable release of Debian).
4524 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4528 As well as the names of actual ("concrete") packages, the
4529 package relationship fields <tt>Depends</tt>,
4530 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4531 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4532 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4533 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4534 may mention "virtual packages".
4538 A <em>virtual package</em> is one which appears in the
4539 <tt>Provides</tt> control file field of another package.
4540 The effect is as if the package(s) which provide a
4541 particular virtual package name had been listed by name
4542 everywhere the virtual package name appears. (See also <ref
4547 If there are both concrete and virtual packages of the same
4548 name, then the dependency may be satisfied (or the conflict
4549 caused) by either the concrete package with the name in
4550 question or any other concrete package which provides the
4551 virtual package with the name in question. This is so that,
4552 for example, supposing we have
4553 <example compact="compact">
4556 </example> and someone else releases an enhanced version of
4557 the <tt>bar</tt> package they can say:
4558 <example compact="compact">
4562 and the <tt>bar-plus</tt> package will now also satisfy the
4563 dependency for the <tt>foo</tt> package.
4567 If a relationship field has a version number attached
4568 then only real packages will be considered to see whether
4569 the relationship is satisfied (or the prohibition violated,
4570 for a conflict or breakage) - it is assumed that a real
4571 package which provides the virtual package is not of the
4572 "right" version. So, a <tt>Provides</tt> field may not
4573 contain version numbers, and the version number of the
4574 concrete package which provides a particular virtual package
4575 will not be looked at when considering a dependency on or
4576 conflict with the virtual package name.
4580 It is likely that the ability will be added in a future
4581 release of <prgn>dpkg</prgn> to specify a version number for
4582 each virtual package it provides. This feature is not yet
4583 present, however, and is expected to be used only
4588 If you want to specify which of a set of real packages
4589 should be the default to satisfy a particular dependency on
4590 a virtual package, you should list the real package as an
4591 alternative before the virtual one.
4596 <sect id="replaces"><heading>Overwriting files and replacing
4597 packages - <tt>Replaces</tt></heading>
4600 Packages can declare in their control file that they should
4601 overwrite files in certain other packages, or completely
4602 replace other packages. The <tt>Replaces</tt> control file
4603 field has these two distinct purposes.
4606 <sect1><heading>Overwriting files in other packages</heading>
4609 Firstly, as mentioned before, it is usually an error for a
4610 package to contain files which are on the system in
4615 However, if the overwriting package declares that it
4616 <tt>Replaces</tt> the one containing the file being
4617 overwritten, then <prgn>dpkg</prgn> will replace the file
4618 from the old package with that from the new. The file
4619 will no longer be listed as "owned" by the old package.
4623 If a package is completely replaced in this way, so that
4624 <prgn>dpkg</prgn> does not know of any files it still
4625 contains, it is considered to have "disappeared". It will
4626 be marked as not wanted on the system (selected for
4627 removal) and not installed. Any <tt>conffile</tt>s
4628 details noted for the package will be ignored, as they
4629 will have been taken over by the overwriting package. The
4630 package's <prgn>postrm</prgn> script will be run with a
4631 special argument to allow the package to do any final
4632 cleanup required. See <ref id="mscriptsinstact">.
4635 Replaces is a one way relationship -- you have to
4636 install the replacing package after the replaced
4643 For this usage of <tt>Replaces</tt>, virtual packages (see
4644 <ref id="virtual">) are not considered when looking at a
4645 <tt>Replaces</tt> field - the packages declared as being
4646 replaced must be mentioned by their real names.
4650 Furthermore, this usage of <tt>Replaces</tt> only takes
4651 effect when both packages are at least partially on the
4652 system at once, so that it can only happen if they do not
4653 conflict or if the conflict has been overridden.
4658 <sect1><heading>Replacing whole packages, forcing their
4662 Secondly, <tt>Replaces</tt> allows the packaging system to
4663 resolve which package should be removed when there is a
4664 conflict - see <ref id="conflicts">. This usage only
4665 takes effect when the two packages <em>do</em> conflict,
4666 so that the two usages of this field do not interfere with
4671 In this situation, the package declared as being replaced
4672 can be a virtual package, so for example, all mail
4673 transport agents (MTAs) would have the following fields in
4674 their control files:
4675 <example compact="compact">
4676 Provides: mail-transport-agent
4677 Conflicts: mail-transport-agent
4678 Replaces: mail-transport-agent
4680 ensuring that only one MTA can be installed at any one
4685 <sect id="sourcebinarydeps">
4686 <heading>Relationships between source and binary packages -
4687 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4688 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4692 Source packages that require certain binary packages to be
4693 installed or absent at the time of building the package
4694 can declare relationships to those binary packages.
4698 This is done using the <tt>Build-Depends</tt>,
4699 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4700 <tt>Build-Conflicts-Indep</tt> control file fields.
4704 Build-dependencies on "build-essential" binary packages can be
4705 omitted. Please see <ref id="pkg-relations"> for more information.
4709 The dependencies and conflicts they define must be satisfied
4710 (as defined earlier for binary packages) in order to invoke
4711 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4713 If you make "build-arch" or "binary-arch", you need
4714 Build-Depends. If you make "build-indep" or
4715 "binary-indep", you need Build-Depends and
4716 Build-Depends-Indep. If you make "build" or "binary",
4720 There is no Build-Depends-Arch; this role is essentially
4721 met with Build-Depends. Anyone building the
4722 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4723 is basically assumed to be building the whole package
4724 anyway and so installs all build dependencies. The
4725 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4726 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4727 does not yet know how to check for its existence) and
4728 <tt>binary-arch</tt>.
4731 The purpose of the original split, I recall, was so that
4732 the autobuilders wouldn't need to install extra packages
4733 needed only for the binary-indep targets. But without a
4734 build-arch/build-indep split, this didn't work, since
4735 most of the work is done in the build target, not in the
4741 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4743 The <tt>Build-Depends</tt> and
4744 <tt>Build-Conflicts</tt> fields must be satisfied when
4745 any of the following targets is invoked:
4746 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4747 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4748 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4750 <tag><tt>Build-Depends-Indep</tt>,
4751 <tt>Build-Conflicts-Indep</tt></tag>
4753 The <tt>Build-Depends-Indep</tt> and
4754 <tt>Build-Conflicts-Indep</tt> fields must be
4755 satisfied when any of the following targets is
4756 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4757 <tt>binary</tt> and <tt>binary-indep</tt>.
4767 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4770 Packages containing shared libraries must be constructed with
4771 a little care to make sure that the shared library is always
4772 available. This is especially important for packages whose
4773 shared libraries are vitally important, such as the C library
4774 (currently <tt>libc6</tt>).
4778 Packages involving shared libraries should be split up into
4779 several binary packages. This section mostly deals with how
4780 this separation is to be accomplished; rules for files within
4781 the shared library packages are in <ref id="libraries"> instead.
4784 <sect id="sharedlibs-runtime">
4785 <heading>Run-time shared libraries</heading>
4788 The run-time shared library needs to be placed in a package
4789 whose name changes whenever the shared object version
4792 Since it is common place to install several versions of a
4793 package that just provides shared libraries, it is a
4794 good idea that the library package should not
4795 contain any extraneous non-versioned files, unless they
4796 happen to be in versioned directories.</p>
4798 The most common mechanism is to place it in a package
4800 <package><var>libraryname</var><var>soversion</var></package>,
4801 where <file><var>soversion</var></file> is the version number
4802 in the soname of the shared library<footnote>
4803 The soname is the shared object name: it's the thing
4804 that has to match exactly between building an executable
4805 and running it for the dynamic linker to be able run the
4806 program. For example, if the soname of the library is
4807 <file>libfoo.so.6</file>, the library package would be
4808 called <file>libfoo6</file>.
4810 Alternatively, if it would be confusing to directly append
4811 <var>soversion</var> to <var>libraryname</var> (e.g. because
4812 <var>libraryname</var> itself ends in a number), you may use
4813 <package><var>libraryname</var>-<var>soversion</var></package> and
4814 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4819 If you have several shared libraries built from the same
4820 source tree you may lump them all together into a single
4821 shared library package, provided that you change all of
4822 their sonames at once (so that you don't get filename
4823 clashes if you try to install different versions of the
4824 combined shared libraries package).
4828 The package should install the shared libraries under
4829 their normal names. For example, the <package>libgdbm3</package>
4830 package should install <file>libgdbm.so.3.0.0</file> as
4831 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4832 renamed or re-linked by any <prgn>prerm</prgn> or
4833 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4834 of renaming things safely without affecting running programs,
4835 and attempts to interfere with this are likely to lead to
4840 Shared libraries should not be installed executable, since
4841 the dynamic linker does not require this and trying to
4842 execute a shared library usually results in a core dump.
4846 The run-time library package should include the symbolic link that
4847 <prgn>ldconfig</prgn> would create for the shared libraries.
4848 For example, the <package>libgdbm3</package> package should include
4849 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4850 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4851 linker (for example <prgn>ld.so</prgn> or
4852 <prgn>ld-linux.so.*</prgn>) can find the library between the
4853 time that <prgn>dpkg</prgn> installs it and the time that
4854 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4856 The package management system requires the library to be
4857 placed before the symbolic link pointing to it in the
4858 <file>.deb</file> file. This is so that when
4859 <prgn>dpkg</prgn> comes to install the symlink
4860 (overwriting the previous symlink pointing at an older
4861 version of the library), the new shared library is already
4862 in place. In the past, this was achieved by creating the
4863 library in the temporary packaging directory before
4864 creating the symlink. Unfortunately, this was not always
4865 effective, since the building of the tar file in the
4866 <file>.deb</file> depended on the behavior of the underlying
4867 file system. Some file systems (such as reiserfs) reorder
4868 the files so that the order of creation is forgotten.
4869 Since version 1.7.0, <prgn>dpkg</prgn>
4870 reorders the files itself as necessary when building a
4871 package. Thus it is no longer important to concern
4872 oneself with the order of file creation.
4876 <sect1 id="ldconfig">
4877 <heading><tt>ldconfig</tt></heading>
4880 Any package installing shared libraries in one of the default
4881 library directories of the dynamic linker (which are currently
4882 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4883 listed in <file>/etc/ld.so.conf</file><footnote>
4885 <list compact="compact">
4886 <item>/usr/local/lib</item>
4887 <item>/usr/lib/libc5-compat</item>
4888 <item>/lib/libc5-compat</item>
4891 must use <prgn>ldconfig</prgn> to update the shared library
4896 The package maintainer scripts must only call
4897 <prgn>ldconfig</prgn> under these circumstances:
4898 <list compact="compact">
4899 <item>When the <prgn>postinst</prgn> script is run with a
4900 first argument of <tt>configure</tt>, the script must call
4901 <prgn>ldconfig</prgn>, and may optionally invoke
4902 <prgn>ldconfig</prgn> at other times.
4904 <item>When the <prgn>postrm</prgn> script is run with a
4905 first argument of <tt>remove</tt>, the script should call
4906 <prgn>ldconfig</prgn>.
4911 During install or upgrade, the preinst is called before
4912 the new files are installed, so calling "ldconfig" is
4913 pointless. The preinst of an existing package can also be
4914 called if an upgrade fails. However, this happens during
4915 the critical time when a shared libs may exist on-disk
4916 under a temporary name. Thus, it is dangerous and
4917 forbidden by current policy to call "ldconfig" at this
4922 When a package is installed or upgraded, "postinst
4923 configure" runs after the new files are safely on-disk.
4924 Since it is perfectly safe to invoke ldconfig
4925 unconditionally in a postinst, it is OK for a package to
4926 simply put ldconfig in its postinst without checking the
4927 argument. The postinst can also be called to recover from
4928 a failed upgrade. This happens before any new files are
4929 unpacked, so there is no reason to call "ldconfig" at this
4934 For a package that is being removed, prerm is
4935 called with all the files intact, so calling ldconfig is
4936 useless. The other calls to "prerm" happen in the case of
4937 upgrade at a time when all the files of the old package
4938 are on-disk, so again calling "ldconfig" is pointless.
4942 postrm, on the other hand, is called with the "remove"
4943 argument just after the files are removed, so this is
4944 the proper time to call "ldconfig" to notify the system
4945 of the fact that the shared libraries from the package
4946 are removed. The postrm can be called at several other
4947 times. At the time of "postrm purge", "postrm
4948 abort-install", or "postrm abort-upgrade", calling
4949 "ldconfig" is useless because the shared lib files are
4950 not on-disk. However, when "postrm" is invoked with
4951 arguments "upgrade", "failed-upgrade", or "disappear", a
4952 shared lib may exist on-disk under a temporary filename.
4960 <sect id="sharedlibs-support-files">
4961 <heading>Shared library support files</heading>
4964 If your package contains files whose names do not change with
4965 each change in the library shared object version, you must not
4966 put them in the shared library package. Otherwise, several
4967 versions of the shared library cannot be installed at the same
4968 time without filename clashes, making upgrades and transitions
4969 unnecessarily difficult.
4973 It is recommended that supporting files and run-time support
4974 programs that do not need to be invoked manually by users, but
4975 are nevertheless required for the package to function, be placed
4976 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
4977 preferably under <file>/usr/lib/</file><var>package-name</var>.
4978 If the program or file is architecture independent, the
4979 recommendation is for it to be placed in a subdirectory of
4980 <file>/usr/share</file> instead, preferably under
4981 <file>/usr/share/</file><var>package-name</var>. Following the
4982 <var>package-name</var> naming convention ensures that the file
4983 names change when the shared object version changes.
4987 Run-time support programs that use the shared library but are
4988 not required for the library to function or files used by the
4989 shared library that can be used by any version of the shared
4990 library package should instead be put in a separate package.
4991 This package might typically be named
4992 <package><var>libraryname</var>-tools</package>; note the
4993 absence of the <var>soversion</var> in the package name.
4997 Files and support programs only useful when compiling software
4998 against the library should be included in the development
4999 package for the library.<footnote>
5000 For example, a <file><var>package-name</var>-config</file>
5001 script or <package>pkg-config</package> configuration files.
5006 <sect id="sharedlibs-static">
5007 <heading>Static libraries</heading>
5010 The static library (<file><var>libraryname.a</var></file>)
5011 is usually provided in addition to the shared version.
5012 It is placed into the development package (see below).
5016 In some cases, it is acceptable for a library to be
5017 available in static form only; these cases include:
5019 <item>libraries for languages whose shared library support
5020 is immature or unstable</item>
5021 <item>libraries whose interfaces are in flux or under
5022 development (commonly the case when the library's
5023 major version number is zero, or where the ABI breaks
5024 across patchlevels)</item>
5025 <item>libraries which are explicitly intended to be
5026 available only in static form by their upstream
5031 <sect id="sharedlibs-dev">
5032 <heading>Development files</heading>
5035 The development files associated to a shared library need to be
5036 placed in a package called
5037 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5038 or if you prefer only to support one development version at a
5039 time, <package><var>libraryname</var>-dev</package>.
5043 In case several development versions of a library exist, you may
5044 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5045 <ref id="conflicts">) to ensure that the user only installs one
5046 development version at a time (as different development versions are
5047 likely to have the same header files in them, which would cause a
5048 filename clash if both were installed).
5052 The development package should contain a symlink for the associated
5053 shared library without a version number. For example, the
5054 <package>libgdbm-dev</package> package should include a symlink
5055 from <file>/usr/lib/libgdbm.so</file> to
5056 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5057 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5058 <file>libgdbm.so</file> when compiling dynamically.
5062 <sect id="sharedlibs-intradeps">
5063 <heading>Dependencies between the packages of the same library</heading>
5066 Typically the development version should have an exact
5067 version dependency on the runtime library, to make sure that
5068 compilation and linking happens correctly. The
5069 <tt>${binary:Version}</tt> substitution variable can be
5070 useful for this purpose.
5072 Previously, <tt>${Source-Version}</tt> was used, but its name
5073 was confusing and it has been deprecated since dpkg 1.13.19.
5078 <sect id="sharedlibs-shlibdeps">
5079 <heading>Dependencies between the library and other packages -
5080 the <tt>shlibs</tt> system</heading>
5083 If a package contains a binary or library which links to a
5084 shared library, we must ensure that when the package is
5085 installed on the system, all of the libraries needed are
5086 also installed. This requirement led to the creation of the
5087 <tt>shlibs</tt> system, which is very simple in its design:
5088 any package which <em>provides</em> a shared library also
5089 provides information on the package dependencies required to
5090 ensure the presence of this library, and any package which
5091 <em>uses</em> a shared library uses this information to
5092 determine the dependencies it requires. The files which
5093 contain the mapping from shared libraries to the necessary
5094 dependency information are called <file>shlibs</file> files.
5098 Thus, when a package is built which contains any shared
5099 libraries, it must provide a <file>shlibs</file> file for other
5100 packages to use, and when a package is built which contains
5101 any shared libraries or compiled binaries, it must run
5102 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5103 on these to determine the libraries used and hence the
5104 dependencies needed by this package.<footnote>
5106 In the past, the shared libraries linked to were
5107 determined by calling <prgn>ldd</prgn>, but now
5108 <prgn>objdump</prgn> is used to do this. The only
5109 change this makes to package building is that
5110 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5111 libraries, whereas in the past this was unnecessary.
5112 The rest of this footnote explains the advantage that
5117 We say that a binary <tt>foo</tt> <em>directly</em> uses
5118 a library <tt>libbar</tt> if it is explicitly linked
5119 with that library (that is, it uses the flag
5120 <tt>-lbar</tt> during the linking stage). Other
5121 libraries that are needed by <tt>libbar</tt> are linked
5122 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5123 linker will load them automatically when it loads
5124 <tt>libbar</tt>. A package should depend on
5125 the libraries it directly uses, and the dependencies for
5126 those libraries should automatically pull in the other
5131 Unfortunately, the <prgn>ldd</prgn> program shows both
5132 the directly and indirectly used libraries, meaning that
5133 the dependencies determined included both direct and
5134 indirect dependencies. The use of <prgn>objdump</prgn>
5135 avoids this problem by determining only the directly
5140 A good example of where this helps is the following. We
5141 could update <tt>libimlib</tt> with a new version that
5142 supports a new graphics format called dgf (but retaining
5143 the same major version number). If we used the old
5144 <prgn>ldd</prgn> method, every package that uses
5145 <tt>libimlib</tt> would need to be recompiled so it
5146 would also depend on <tt>libdgf</tt> or it wouldn't run
5147 due to missing symbols. However with the new system,
5148 packages using <tt>libimlib</tt> can rely on
5149 <tt>libimlib</tt> itself having the dependency on
5150 <tt>libdgf</tt> and so they would not need rebuilding.
5156 In the following sections, we will first describe where the
5157 various <tt>shlibs</tt> files are to be found, then how to
5158 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5159 file format and how to create them if your package contains a
5164 <heading>The <tt>shlibs</tt> files present on the system</heading>
5167 There are several places where <tt>shlibs</tt> files are
5168 found. The following list gives them in the order in which
5170 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5171 (The first one which gives the required information is used.)
5177 <p><file>debian/shlibs.local</file></p>
5180 This lists overrides for this package. Its use is
5181 described below (see <ref id="shlibslocal">).
5186 <p><file>/etc/dpkg/shlibs.override</file></p>
5189 This lists global overrides. This list is normally
5190 empty. It is maintained by the local system
5196 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5199 When packages are being built, any
5200 <file>debian/shlibs</file> files are copied into the
5201 control file area of the temporary build directory and
5202 given the name <file>shlibs</file>. These files give
5203 details of any shared libraries included in the
5205 An example may help here. Let us say that the
5206 source package <tt>foo</tt> generates two binary
5207 packages, <tt>libfoo2</tt> and
5208 <tt>foo-runtime</tt>. When building the binary
5209 packages, the two packages are created in the
5210 directories <file>debian/libfoo2</file> and
5211 <file>debian/foo-runtime</file> respectively.
5212 (<file>debian/tmp</file> could be used instead of one
5213 of these.) Since <tt>libfoo2</tt> provides the
5214 <tt>libfoo</tt> shared library, it will require a
5215 <tt>shlibs</tt> file, which will be installed in
5216 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5218 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5219 when <prgn>dpkg-shlibdeps</prgn> is run on the
5221 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5223 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5224 determine whether <tt>foo-prog</tt>'s library
5225 dependencies are satisfied by any of the libraries
5226 provided by <tt>libfoo2</tt>. For this reason,
5227 <prgn>dpkg-shlibdeps</prgn> must only be run once
5228 all of the individual binary packages'
5229 <tt>shlibs</tt> files have been installed into the
5236 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5239 These are the <file>shlibs</file> files corresponding to
5240 all of the packages installed on the system, and are
5241 maintained by the relevant package maintainers.
5246 <p><file>/etc/dpkg/shlibs.default</file></p>
5249 This file lists any shared libraries whose packages
5250 have failed to provide correct <file>shlibs</file> files.
5251 It was used when the <file>shlibs</file> setup was first
5252 introduced, but it is now normally empty. It is
5253 maintained by the <tt>dpkg</tt> maintainer.
5261 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5262 <file>shlibs</file> files</heading>
5266 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5267 into your <file>debian/rules</file> file. If your package
5268 contains only compiled binaries and libraries (but no scripts),
5269 you can use a command such as:
5270 <example compact="compact">
5271 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5272 debian/tmp/usr/lib/*
5274 Otherwise, you will need to explicitly list the compiled
5275 binaries and libraries.<footnote>
5276 If you are using <tt>debhelper</tt>, the
5277 <prgn>dh_shlibdeps</prgn> program will do this work for
5278 you. It will also correctly handle multi-binary
5284 This command puts the dependency information into the
5285 <file>debian/substvars</file> file, which is then used by
5286 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5287 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5288 field in the control file for this to work.
5292 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5293 done. If it does complain you might need to create your own
5294 <file>debian/shlibs.local</file> file, as explained below (see
5295 <ref id="shlibslocal">).
5299 If you have multiple binary packages, you will need to call
5300 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5301 compiled libraries or binaries. In such a case, you will
5302 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5303 utilities to specify a different <file>substvars</file> file.
5307 If you are creating a udeb for use in the Debian Installer, you
5308 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5309 the dependency line of type <tt>udeb</tt> by adding
5310 <tt>-tudeb</tt> as option<footnote>
5311 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5312 will automatically add this option if it knows it is
5314 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5315 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5316 fall back to the regular dependency line.
5320 For more details on dpkg-shlibdeps, please see
5321 <ref id="pkg-dpkg-shlibdeps"> and
5322 <manref name="dpkg-shlibdeps" section="1">.
5327 <heading>The <file>shlibs</file> File Format</heading>
5330 Each <file>shlibs</file> file has the same format. Lines
5331 beginning with <tt>#</tt> are considered to be comments and
5332 are ignored. Each line is of the form:
5333 <example compact="compact">
5334 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5339 We will explain this by reference to the example of the
5340 <tt>zlib1g</tt> package, which (at the time of writing)
5341 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5345 <var>type</var> is an optional element that indicates the type
5346 of package for which the line is valid. The only type currently
5347 in use is <tt>udeb</tt>. The colon and space after the type are
5352 <var>library-name</var> is the name of the shared library,
5353 in this case <tt>libz</tt>. (This must match the name part
5354 of the soname, see below.)
5358 <var>soname-version</var> is the version part of the soname of
5359 the library. The soname is the thing that must exactly match
5360 for the library to be recognized by the dynamic linker, and is
5362 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5363 example, <tt>libz.so.1</tt>.<footnote>
5364 This can be determined using the command
5365 <example compact="compact">
5366 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5369 The version part is the part which comes after
5370 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5374 <var>dependencies</var> has the same syntax as a dependency
5375 field in a binary package control file. It should give
5376 details of which packages are required to satisfy a binary
5377 built against the version of the library contained in the
5378 package. See <ref id="depsyntax"> for details.
5382 In our example, if the first version of the <tt>zlib1g</tt>
5383 package which contained a minor number of at least
5384 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5385 <tt>shlibs</tt> entry for this library could say:
5386 <example compact="compact">
5387 libz 1 zlib1g (>= 1:1.1.3)
5389 The version-specific dependency is to avoid warnings from
5390 the dynamic linker about using older shared libraries with
5395 As zlib1g also provides a udeb containing the shared library,
5396 there would also be a second line:
5397 <example compact="compact">
5398 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5404 <heading>Providing a <file>shlibs</file> file</heading>
5407 If your package provides a shared library, you need to create
5408 a <file>shlibs</file> file following the format described above.
5409 It is usual to call this file <file>debian/shlibs</file> (but if
5410 you have multiple binary packages, you might want to call it
5411 <file>debian/shlibs.<var>package</var></file> instead). Then
5412 let <file>debian/rules</file> install it in the control area:
5413 <example compact="compact">
5414 install -m644 debian/shlibs debian/tmp/DEBIAN
5416 or, in the case of a multi-binary package:
5417 <example compact="compact">
5418 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5420 An alternative way of doing this is to create the
5421 <file>shlibs</file> file in the control area directly from
5422 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5423 file at all,<footnote>
5424 This is what <prgn>dh_makeshlibs</prgn> in the
5425 <tt>debhelper</tt> suite does. If your package also has a udeb
5426 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5427 automatically generate the <tt>udeb:</tt> lines if you specify
5428 the name of the udeb with the <tt>--add-udeb</tt> option.
5430 since the <file>debian/shlibs</file> file itself is ignored by
5431 <prgn>dpkg-shlibdeps</prgn>.
5435 As <prgn>dpkg-shlibdeps</prgn> reads the
5436 <file>DEBIAN/shlibs</file> files in all of the binary packages
5437 being built from this source package, all of the
5438 <file>DEBIAN/shlibs</file> files should be installed before
5439 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5444 <sect1 id="shlibslocal">
5445 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5448 This file is intended only as a <em>temporary</em> fix if
5449 your binaries or libraries depend on a library whose package
5450 does not yet provide a correct <file>shlibs</file> file.
5454 We will assume that you are trying to package a binary
5455 <tt>foo</tt>. When you try running
5456 <prgn>dpkg-shlibdeps</prgn> you get the following error
5457 message (<tt>-O</tt> displays the dependency information on
5458 <tt>stdout</tt> instead of writing it to
5459 <tt>debian/substvars</tt>, and the lines have been wrapped
5460 for ease of reading):
5461 <example compact="compact">
5462 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5463 dpkg-shlibdeps: warning: unable to find dependency
5464 information for shared library libbar (soname 1,
5465 path /usr/lib/libbar.so.1, dependency field Depends)
5466 shlibs:Depends=libc6 (>= 2.2.2-2)
5468 You can then run <prgn>ldd</prgn> on the binary to find the
5469 full location of the library concerned:
5470 <example compact="compact">
5472 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5473 libc.so.6 => /lib/libc.so.6 (0x40032000)
5474 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5476 So the <prgn>foo</prgn> binary depends on the
5477 <prgn>libbar</prgn> shared library, but no package seems to
5478 provide a <file>*.shlibs</file> file handling
5479 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5480 determine the package responsible:
5481 <example compact="compact">
5482 $ dpkg -S /usr/lib/libbar.so.1
5483 bar1: /usr/lib/libbar.so.1
5484 $ dpkg -s bar1 | grep Version
5487 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5488 is the one we are using. Now we can file a bug against the
5489 <tt>bar1</tt> package and create our own
5490 <file>debian/shlibs.local</file> to locally fix the problem.
5491 Including the following line into your
5492 <file>debian/shlibs.local</file> file:
5493 <example compact="compact">
5494 libbar 1 bar1 (>= 1.0-1)
5496 should allow the package build to work.
5500 As soon as the maintainer of <tt>bar1</tt> provides a
5501 correct <file>shlibs</file> file, you should remove this line
5502 from your <file>debian/shlibs.local</file> file. (You should
5503 probably also then have a versioned <tt>Build-Depends</tt>
5504 on <tt>bar1</tt> to help ensure that others do not have the
5505 same problem building your package.)
5514 <chapt id="opersys"><heading>The Operating System</heading>
5517 <heading>File system hierarchy</heading>
5521 <heading>File system Structure</heading>
5524 The location of all installed files and directories must
5525 comply with the File system Hierarchy Standard (FHS),
5526 version 2.3, with the exceptions noted below, and except
5527 where doing so would violate other terms of Debian
5528 Policy. The following exceptions to the FHS apply:
5533 Legacy XFree86 servers are permitted to retain the
5534 configuration file location
5535 <file>/etc/X11/XF86Config-4</file>.
5540 The optional rules related to user specific
5541 configuration files for applications are stored in
5542 the user's home directory are relaxed. It is
5543 recommended that such files start with the
5544 '<tt>.</tt>' character (a "dot file"), and if an
5545 application needs to create more than one dot file
5546 then the preferred placement is in a subdirectory
5547 with a name starting with a '.' character, (a "dot
5548 directory"). In this case it is recommended the
5549 configuration files not start with the '.'
5555 The requirement for amd64 to use <file>/lib64</file>
5556 for 64 bit binaries is removed.
5561 The requirement that
5562 <file>/usr/local/share/man</file> be "synonymous"
5563 with <file>/usr/local/man</file> is relaxed to a
5568 The requirement that windowmanagers with a single
5569 configuration file call it <file>system.*wmrc</file>
5570 is removed, as is the restriction that the window
5571 manager subdirectory be named identically to the
5572 window manager name itself.
5577 The requirement that boot manager configuration
5578 files live in <file>/etc</file>, or at least are
5579 symlinked there, is relaxed to a recommendation.
5586 The version of this document referred here can be
5587 found in the <tt>debian-policy</tt> package or on <url
5588 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5589 name="FHS (Debian copy)"> alongside this manual (or, if
5590 you have the <package>debian-policy</package> installed,
5592 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5593 (local copy)">). The
5594 latest version, which may be a more recent version, may
5596 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5597 Specific questions about following the standard may be
5598 asked on the <tt>debian-devel</tt> mailing list, or
5599 referred to the FHS mailing list (see the
5600 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5606 <heading>Site-specific programs</heading>
5609 As mandated by the FHS, packages must not place any
5610 files in <file>/usr/local</file>, either by putting them in
5611 the file system archive to be unpacked by <prgn>dpkg</prgn>
5612 or by manipulating them in their maintainer scripts.
5616 However, the package may create empty directories below
5617 <file>/usr/local</file> so that the system administrator knows
5618 where to place site-specific files. These are not
5619 directories <em>in</em> <file>/usr/local</file>, but are
5620 children of directories in <file>/usr/local</file>. These
5621 directories (<file>/usr/local/*/dir/</file>)
5622 should be removed on package removal if they are
5627 Note, that this applies only to directories <em>below</em>
5628 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5629 Packages must not create sub-directories in the directory
5630 <file>/usr/local</file> itself, except those listed in FHS,
5631 section 4.5. However, you may create directories below
5632 them as you wish. You must not remove any of the
5633 directories listed in 4.5, even if you created them.
5637 Since <file>/usr/local</file> can be mounted read-only from a
5638 remote server, these directories must be created and
5639 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5640 maintainer scripts and not be included in the
5641 <file>.deb</file> archive. These scripts must not fail if
5642 either of these operations fail.
5646 For example, the <tt>emacsen-common</tt> package could
5647 contain something like
5648 <example compact="compact">
5649 if [ ! -e /usr/local/share/emacs ]
5651 if mkdir /usr/local/share/emacs 2>/dev/null
5653 chown root:staff /usr/local/share/emacs
5654 chmod 2775 /usr/local/share/emacs
5658 in its <prgn>postinst</prgn> script, and
5659 <example compact="compact">
5660 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5661 rmdir /usr/local/share/emacs 2>/dev/null || true
5663 in the <prgn>prerm</prgn> script. (Note that this form is
5664 used to ensure that if the script is interrupted, the
5665 directory <file>/usr/local/share/emacs</file> will still be
5670 If you do create a directory in <file>/usr/local</file> for
5671 local additions to a package, you should ensure that
5672 settings in <file>/usr/local</file> take precedence over the
5673 equivalents in <file>/usr</file>.
5677 However, because <file>/usr/local</file> and its contents are
5678 for exclusive use of the local administrator, a package
5679 must not rely on the presence or absence of files or
5680 directories in <file>/usr/local</file> for normal operation.
5684 The <file>/usr/local</file> directory itself and all the
5685 subdirectories created by the package should (by default) have
5686 permissions 2775 (group-writable and set-group-id) and be
5687 owned by <tt>root:staff</tt>.
5692 <heading>The system-wide mail directory</heading>
5694 The system-wide mail directory is <file>/var/mail</file>. This
5695 directory is part of the base system and should not owned
5696 by any particular mail agents. The use of the old
5697 location <file>/var/spool/mail</file> is deprecated, even
5698 though the spool may still be physically located there.
5699 To maintain partial upgrade compatibility for systems
5700 which have <file>/var/spool/mail</file> as their physical mail
5701 spool, packages using <file>/var/mail</file> must depend on
5702 either <package>libc6</package> (>= 2.1.3-13), or on
5703 <package>base-files</package> (>= 2.2.0), or on later
5704 versions of either one of these packages.
5710 <heading>Users and groups</heading>
5713 <heading>Introduction</heading>
5715 The Debian system can be configured to use either plain or
5720 Some user ids (UIDs) and group ids (GIDs) are reserved
5721 globally for use by certain packages. Because some
5722 packages need to include files which are owned by these
5723 users or groups, or need the ids compiled into binaries,
5724 these ids must be used on any Debian system only for the
5725 purpose for which they are allocated. This is a serious
5726 restriction, and we should avoid getting in the way of
5727 local administration policies. In particular, many sites
5728 allocate users and/or local system groups starting at 100.
5732 Apart from this we should have dynamically allocated ids,
5733 which should by default be arranged in some sensible
5734 order, but the behavior should be configurable.
5738 Packages other than <tt>base-passwd</tt> must not modify
5739 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5740 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5745 <heading>UID and GID classes</heading>
5747 The UID and GID numbers are divided into classes as
5753 Globally allocated by the Debian project, the same
5754 on every Debian system. These ids will appear in
5755 the <file>passwd</file> and <file>group</file> files of all
5756 Debian systems, new ids in this range being added
5757 automatically as the <tt>base-passwd</tt> package is
5762 Packages which need a single statically allocated
5763 uid or gid should use one of these; their
5764 maintainers should ask the <tt>base-passwd</tt>
5772 Dynamically allocated system users and groups.
5773 Packages which need a user or group, but can have
5774 this user or group allocated dynamically and
5775 differently on each system, should use <tt>adduser
5776 --system</tt> to create the group and/or user.
5777 <prgn>adduser</prgn> will check for the existence of
5778 the user or group, and if necessary choose an unused
5779 id based on the ranges specified in
5780 <file>adduser.conf</file>.
5784 <tag>1000-29999:</tag>
5787 Dynamically allocated user accounts. By default
5788 <prgn>adduser</prgn> will choose UIDs and GIDs for
5789 user accounts in this range, though
5790 <file>adduser.conf</file> may be used to modify this
5795 <tag>30000-59999:</tag>
5800 <tag>60000-64999:</tag>
5803 Globally allocated by the Debian project, but only
5804 created on demand. The ids are allocated centrally
5805 and statically, but the actual accounts are only
5806 created on users' systems on demand.
5810 These ids are for packages which are obscure or
5811 which require many statically-allocated ids. These
5812 packages should check for and create the accounts in
5813 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5814 <prgn>adduser</prgn> if it has this facility) if
5815 necessary. Packages which are likely to require
5816 further allocations should have a "hole" left after
5817 them in the allocation, to give them room to
5822 <tag>65000-65533:</tag>
5830 User <tt>nobody</tt>. The corresponding gid refers
5831 to the group <tt>nogroup</tt>.
5838 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5839 not</em> be used, because it is the error return
5848 <sect id="sysvinit">
5849 <heading>System run levels and <file>init.d</file> scripts</heading>
5851 <sect1 id="/etc/init.d">
5852 <heading>Introduction</heading>
5855 The <file>/etc/init.d</file> directory contains the scripts
5856 executed by <prgn>init</prgn> at boot time and when the
5857 init state (or "runlevel") is changed (see <manref
5858 name="init" section="8">).
5862 There are at least two different, yet functionally
5863 equivalent, ways of handling these scripts. For the sake
5864 of simplicity, this document describes only the symbolic
5865 link method. However, it must not be assumed by maintainer
5866 scripts that this method is being used, and any automated
5867 manipulation of the various runlevel behaviors by
5868 maintainer scripts must be performed using
5869 <prgn>update-rc.d</prgn> as described below and not by
5870 manually installing or removing symlinks. For information
5871 on the implementation details of the other method,
5872 implemented in the <tt>file-rc</tt> package, please refer
5873 to the documentation of that package.
5877 These scripts are referenced by symbolic links in the
5878 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5879 runlevels, <prgn>init</prgn> looks in the directory
5880 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5881 execute, where <tt><var>n</var></tt> is the runlevel that
5882 is being changed to, or <tt>S</tt> for the boot-up
5887 The names of the links all have the form
5888 <file>S<var>mm</var><var>script</var></file> or
5889 <file>K<var>mm</var><var>script</var></file> where
5890 <var>mm</var> is a two-digit number and <var>script</var>
5891 is the name of the script (this should be the same as the
5892 name of the actual script in <file>/etc/init.d</file>).
5896 When <prgn>init</prgn> changes runlevel first the targets
5897 of the links whose names start with a <tt>K</tt> are
5898 executed, each with the single argument <tt>stop</tt>,
5899 followed by the scripts prefixed with an <tt>S</tt>, each
5900 with the single argument <tt>start</tt>. (The links are
5901 those in the <file>/etc/rc<var>n</var>.d</file> directory
5902 corresponding to the new runlevel.) The <tt>K</tt> links
5903 are responsible for killing services and the <tt>S</tt>
5904 link for starting services upon entering the runlevel.
5908 For example, if we are changing from runlevel 2 to
5909 runlevel 3, init will first execute all of the <tt>K</tt>
5910 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5911 all of the <tt>S</tt> prefixed scripts in that directory.
5912 The links starting with <tt>K</tt> will cause the
5913 referred-to file to be executed with an argument of
5914 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5919 The two-digit number <var>mm</var> is used to determine
5920 the order in which to run the scripts: low-numbered links
5921 have their scripts run first. For example, the
5922 <tt>K20</tt> scripts will be executed before the
5923 <tt>K30</tt> scripts. This is used when a certain service
5924 must be started before another. For example, the name
5925 server <prgn>bind</prgn> might need to be started before
5926 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5927 can set up its access lists. In this case, the script
5928 that starts <prgn>bind</prgn> would have a lower number
5929 than the script that starts <prgn>inn</prgn> so that it
5931 <example compact="compact">
5938 The two runlevels 0 (halt) and 6 (reboot) are slightly
5939 different. In these runlevels, the links with an
5940 <tt>S</tt> prefix are still called after those with a
5941 <tt>K</tt> prefix, but they too are called with the single
5942 argument <tt>stop</tt>.
5947 <heading>Writing the scripts</heading>
5950 Packages that include daemons for system services should
5951 place scripts in <file>/etc/init.d</file> to start or stop
5952 services at boot time or during a change of runlevel.
5953 These scripts should be named
5954 <file>/etc/init.d/<var>package</var></file>, and they should
5955 accept one argument, saying what to do:
5958 <tag><tt>start</tt></tag>
5959 <item>start the service,</item>
5961 <tag><tt>stop</tt></tag>
5962 <item>stop the service,</item>
5964 <tag><tt>restart</tt></tag>
5965 <item>stop and restart the service if it's already running,
5966 otherwise start the service</item>
5968 <tag><tt>reload</tt></tag>
5969 <item><p>cause the configuration of the service to be
5970 reloaded without actually stopping and restarting
5973 <tag><tt>force-reload</tt></tag>
5974 <item>cause the configuration to be reloaded if the
5975 service supports this, otherwise restart the
5979 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5980 <tt>force-reload</tt> options should be supported by all
5981 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5986 The <file>init.d</file> scripts must ensure that they will
5987 behave sensibly (i.e., returning success and not starting
5988 multiple copies of a service) if invoked with <tt>start</tt>
5989 when the service is already running, or with <tt>stop</tt>
5990 when it isn't, and that they don't kill unfortunately-named
5991 user processes. The best way to achieve this is usually to
5992 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
5997 If a service reloads its configuration automatically (as
5998 in the case of <prgn>cron</prgn>, for example), the
5999 <tt>reload</tt> option of the <file>init.d</file> script
6000 should behave as if the configuration has been reloaded
6005 The <file>/etc/init.d</file> scripts must be treated as
6006 configuration files, either (if they are present in the
6007 package, that is, in the .deb file) by marking them as
6008 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6009 by managing them correctly in the maintainer scripts (see
6010 <ref id="config-files">). This is important since we want
6011 to give the local system administrator the chance to adapt
6012 the scripts to the local system, e.g., to disable a
6013 service without de-installing the package, or to specify
6014 some special command line options when starting a service,
6015 while making sure their changes aren't lost during the next
6020 These scripts should not fail obscurely when the
6021 configuration files remain but the package has been
6022 removed, as configuration files remain on the system after
6023 the package has been removed. Only when <prgn>dpkg</prgn>
6024 is executed with the <tt>--purge</tt> option will
6025 configuration files be removed. In particular, as the
6026 <file>/etc/init.d/<var>package</var></file> script itself is
6027 usually a <tt>conffile</tt>, it will remain on the system
6028 if the package is removed but not purged. Therefore, you
6029 should include a <tt>test</tt> statement at the top of the
6031 <example compact="compact">
6032 test -f <var>program-executed-later-in-script</var> || exit 0
6037 Often there are some variables in the <file>init.d</file>
6038 scripts whose values control the behavior of the scripts,
6039 and which a system administrator is likely to want to
6040 change. As the scripts themselves are frequently
6041 <tt>conffile</tt>s, modifying them requires that the
6042 administrator merge in their changes each time the package
6043 is upgraded and the <tt>conffile</tt> changes. To ease
6044 the burden on the system administrator, such configurable
6045 values should not be placed directly in the script.
6046 Instead, they should be placed in a file in
6047 <file>/etc/default</file>, which typically will have the same
6048 base name as the <file>init.d</file> script. This extra file
6049 should be sourced by the script when the script runs. It
6050 must contain only variable settings and comments in SUSv3
6051 <prgn>sh</prgn> format. It may either be a
6052 <tt>conffile</tt> or a configuration file maintained by
6053 the package maintainer scripts. See <ref id="config-files">
6058 To ensure that vital configurable values are always
6059 available, the <file>init.d</file> script should set default
6060 values for each of the shell variables it uses, either
6061 before sourcing the <file>/etc/default/</file> file or
6062 afterwards using something like the <tt>:
6063 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6064 script must behave sensibly and not fail if the
6065 <file>/etc/default</file> file is deleted.
6069 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6070 as temporary filesystems<footnote>
6071 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6072 options in <file>/etc/default/rcS</file>.
6073 </footnote>, so the <file>init.d</file> scripts must handle this
6074 correctly. This will typically amount to creating any required
6075 subdirectories dynamically when the <file>init.d</file> script
6076 is run, rather than including them in the package and relying on
6077 <prgn>dpkg</prgn> to create them.
6082 <heading>Interfacing with the initscript system</heading>
6085 Maintainers should use the abstraction layer provided by
6086 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6087 programs to deal with initscripts in their packages'
6088 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6089 and <prgn>postrm</prgn>.
6093 Directly managing the /etc/rc?.d links and directly
6094 invoking the <file>/etc/init.d/</file> initscripts should
6095 be done only by packages providing the initscript
6096 subsystem (such as <prgn>sysv-rc</prgn> and
6097 <prgn>file-rc</prgn>).
6101 <heading>Managing the links</heading>
6104 The program <prgn>update-rc.d</prgn> is provided for
6105 package maintainers to arrange for the proper creation and
6106 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6107 or their functional equivalent if another method is being
6108 used. This may be used by maintainers in their packages'
6109 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6113 You must not include any <file>/etc/rc<var>n</var>.d</file>
6114 symbolic links in the actual archive or manually create or
6115 remove the symbolic links in maintainer scripts; you must
6116 use the <prgn>update-rc.d</prgn> program instead. (The
6117 former will fail if an alternative method of maintaining
6118 runlevel information is being used.) You must not include
6119 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6120 in the archive either. (Only the <tt>sysvinit</tt>
6125 By default <prgn>update-rc.d</prgn> will start services in
6126 each of the multi-user state runlevels (2, 3, 4, and 5)
6127 and stop them in the halt runlevel (0), the single-user
6128 runlevel (1) and the reboot runlevel (6). The system
6129 administrator will have the opportunity to customize
6130 runlevels by simply adding, moving, or removing the
6131 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6132 symbolic links are being used, or by modifying
6133 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6138 To get the default behavior for your package, put in your
6139 <prgn>postinst</prgn> script
6140 <example compact="compact">
6141 update-rc.d <var>package</var> defaults
6143 and in your <prgn>postrm</prgn>
6144 <example compact="compact">
6145 if [ "$1" = purge ]; then
6146 update-rc.d <var>package</var> remove
6148 </example>. Note that if your package changes runlevels
6149 or priority, you may have to remove and recreate the links,
6150 since otherwise the old links may persist. Refer to the
6151 documentation of <prgn>update-rc.d</prgn>.
6155 This will use a default sequence number of 20. If it does
6156 not matter when or in which order the <file>init.d</file>
6157 script is run, use this default. If it does, then you
6158 should talk to the maintainer of the <prgn>sysvinit</prgn>
6159 package or post to <tt>debian-devel</tt>, and they will
6160 help you choose a number.
6164 For more information about using <tt>update-rc.d</tt>,
6165 please consult its man page <manref name="update-rc.d"
6171 <heading>Running initscripts</heading>
6173 The program <prgn>invoke-rc.d</prgn> is provided to make
6174 it easier for package maintainers to properly invoke an
6175 initscript, obeying runlevel and other locally-defined
6176 constraints that might limit a package's right to start,
6177 stop and otherwise manage services. This program may be
6178 used by maintainers in their packages' scripts.
6182 The package maintainer scripts must use
6183 <prgn>invoke-rc.d</prgn> to invoke the
6184 <file>/etc/init.d/*</file> initscripts, instead of
6185 calling them directly.
6189 By default, <prgn>invoke-rc.d</prgn> will pass any
6190 action requests (start, stop, reload, restart...) to the
6191 <file>/etc/init.d</file> script, filtering out requests
6192 to start or restart a service out of its intended
6197 Most packages will simply need to change:
6198 <example compact="compact">/etc/init.d/<package>
6199 <action></example> in their <prgn>postinst</prgn>
6200 and <prgn>prerm</prgn> scripts to:
6201 <example compact="compact">
6202 if which invoke-rc.d >/dev/null 2>&1; then
6203 invoke-rc.d <var>package</var> <action>
6205 /etc/init.d/<var>package</var> <action>
6211 A package should register its initscript services using
6212 <prgn>update-rc.d</prgn> before it tries to invoke them
6213 using <prgn>invoke-rc.d</prgn>. Invocation of
6214 unregistered services may fail.
6218 For more information about using
6219 <prgn>invoke-rc.d</prgn>, please consult its man page
6220 <manref name="invoke-rc.d" section="8">.
6226 <heading>Boot-time initialization</heading>
6229 There used to be another directory, <file>/etc/rc.boot</file>,
6230 which contained scripts which were run once per machine
6231 boot. This has been deprecated in favour of links from
6232 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6233 described in <ref id="/etc/init.d">. Packages must not
6234 place files in <file>/etc/rc.boot</file>.
6239 <heading>Example</heading>
6242 An example on which you can base your
6243 <file>/etc/init.d</file> scripts is found in
6244 <file>/etc/init.d/skeleton</file>.
6251 <heading>Console messages from <file>init.d</file> scripts</heading>
6254 This section describes the formats to be used for messages
6255 written to standard output by the <file>/etc/init.d</file>
6256 scripts. The intent is to improve the consistency of
6257 Debian's startup and shutdown look and feel. For this
6258 reason, please look very carefully at the details. We want
6259 the messages to have the same format in terms of wording,
6260 spaces, punctuation and case of letters.
6264 Here is a list of overall rules that should be used for
6265 messages generated by <file>/etc/init.d</file> scripts.
6271 The message should fit in one line (fewer than 80
6272 characters), start with a capital letter and end with
6273 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6277 If the script is performing some time consuming task in
6278 the background (not merely starting or stopping a
6279 program, for instance), an ellipsis (three dots:
6280 <tt>...</tt>) should be output to the screen, with no
6281 leading or tailing whitespace or line feeds.
6285 The messages should appear as if the computer is telling
6286 the user what it is doing (politely :-), but should not
6287 mention "it" directly. For example, instead of:
6288 <example compact="compact">
6289 I'm starting network daemons: nfsd mountd.
6291 the message should say
6292 <example compact="compact">
6293 Starting network daemons: nfsd mountd.
6300 <tt>init.d</tt> script should use the following standard
6301 message formats for the situations enumerated below.
6307 <p>When daemons are started</p>
6310 If the script starts one or more daemons, the output
6311 should look like this (a single line, no leading
6313 <example compact="compact">
6314 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6316 The <var>description</var> should describe the
6317 subsystem the daemon or set of daemons are part of,
6318 while <var>daemon-1</var> up to <var>daemon-n</var>
6319 denote each daemon's name (typically the file name of
6324 For example, the output of <file>/etc/init.d/lpd</file>
6326 <example compact="compact">
6327 Starting printer spooler: lpd.
6332 This can be achieved by saying
6333 <example compact="compact">
6334 echo -n "Starting printer spooler: lpd"
6335 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6338 in the script. If there are more than one daemon to
6339 start, the output should look like this:
6340 <example compact="compact">
6341 echo -n "Starting remote file system services:"
6342 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6343 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6344 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6347 This makes it possible for the user to see what is
6348 happening and when the final daemon has been started.
6349 Care should be taken in the placement of white spaces:
6350 in the example above the system administrators can
6351 easily comment out a line if they don't want to start
6352 a specific daemon, while the displayed message still
6358 <p>When a system parameter is being set</p>
6361 If you have to set up different system parameters
6362 during the system boot, you should use this format:
6363 <example compact="compact">
6364 Setting <var>parameter</var> to "<var>value</var>".
6369 You can use a statement such as the following to get
6371 <example compact="compact">
6372 echo "Setting DNS domainname to \"$domainname\"."
6377 Note that the same symbol (<tt>"</tt>) is used for the left
6378 and right quotation marks. A grave accent (<tt>`</tt>) is
6379 not a quote character; neither is an apostrophe
6385 <p>When a daemon is stopped or restarted</p>
6388 When you stop or restart a daemon, you should issue a
6389 message identical to the startup message, except that
6390 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6391 or <tt>Restarting</tt> respectively.
6395 For example, stopping the printer daemon will look like
6397 <example compact="compact">
6398 Stopping printer spooler: lpd.
6404 <p>When something is executed</p>
6407 There are several examples where you have to run a
6408 program at system startup or shutdown to perform a
6409 specific task, for example, setting the system's clock
6410 using <prgn>netdate</prgn> or killing all processes
6411 when the system shuts down. Your message should look
6413 <example compact="compact">
6414 Doing something very useful...done.
6416 You should print the <tt>done.</tt> immediately after
6417 the job has been completed, so that the user is
6418 informed why they have to wait. You can get this
6420 <example compact="compact">
6421 echo -n "Doing something very useful..."
6430 <p>When the configuration is reloaded</p>
6433 When a daemon is forced to reload its configuration
6434 files you should use the following format:
6435 <example compact="compact">
6436 Reloading <var>description</var> configuration...done.
6438 where <var>description</var> is the same as in the
6439 daemon starting message.
6447 <heading>Cron jobs</heading>
6450 Packages must not modify the configuration file
6451 <file>/etc/crontab</file>, and they must not modify the files in
6452 <file>/var/spool/cron/crontabs</file>.</p>
6455 If a package wants to install a job that has to be executed
6456 via cron, it should place a file with the name of the
6457 package in one or more of the following directories:
6458 <example compact="compact">
6464 As these directory names imply, the files within them are
6465 executed on an hourly, daily, weekly, or monthly basis,
6466 respectively. The exact times are listed in
6467 <file>/etc/crontab</file>.</p>
6470 All files installed in any of these directories must be
6471 scripts (e.g., shell scripts or Perl scripts) so that they
6472 can easily be modified by the local system administrator.
6473 In addition, they must be treated as configuration files.
6477 If a certain job has to be executed at some other frequency or
6478 at a specific time, the package should install a file
6479 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6480 same syntax as <file>/etc/crontab</file> and is processed by
6481 <prgn>cron</prgn> automatically. The file must also be
6482 treated as a configuration file. (Note that entries in the
6483 <file>/etc/cron.d</file> directory are not handled by
6484 <prgn>anacron</prgn>. Thus, you should only use this
6485 directory for jobs which may be skipped if the system is not
6489 The scripts or crontab entries in these directories should
6490 check if all necessary programs are installed before they
6491 try to execute them. Otherwise, problems will arise when a
6492 package was removed but not purged since configuration files
6493 are kept on the system in this situation.</p>
6497 <heading>Menus</heading>
6500 The Debian <tt>menu</tt> package provides a standard
6501 interface between packages providing applications and
6502 <em>menu programs</em> (either X window managers or
6503 text-based menu programs such as <prgn>pdmenu</prgn>).
6507 All packages that provide applications that need not be
6508 passed any special command line arguments for normal
6509 operation should register a menu entry for those
6510 applications, so that users of the <tt>menu</tt> package
6511 will automatically get menu entries in their window
6512 managers, as well in shells like <tt>pdmenu</tt>.
6516 Menu entries should follow the current menu policy.
6520 The menu policy can be found in the <tt>menu-policy</tt>
6521 files in the <tt>debian-policy</tt> package.
6522 It is also available from the Debian web mirrors at
6523 <tt><url name="/doc/packaging-manuals/menu-policy/"
6524 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6528 Please also refer to the <em>Debian Menu System</em>
6529 documentation that comes with the <package>menu</package>
6530 package for information about how to register your
6536 <heading>Multimedia handlers</heading>
6539 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6540 is a mechanism for encoding files and data streams and
6541 providing meta-information about them, in particular their
6542 type (e.g. audio or video) and format (e.g. PNG, HTML,
6547 Registration of MIME type handlers allows programs like mail
6548 user agents and web browsers to invoke these handlers to
6549 view, edit or display MIME types they don't support directly.
6553 Packages which provide the ability to view/show/play,
6554 compose, edit or print MIME types should register themselves
6555 as such following the current MIME support policy.
6559 The MIME support policy can be found in the <tt>mime-policy</tt>
6560 files in the <tt>debian-policy</tt> package.
6561 It is also available from the Debian web mirrors at
6562 <tt><url name="/doc/packaging-manuals/mime-policy/"
6563 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6569 <heading>Keyboard configuration</heading>
6572 To achieve a consistent keyboard configuration so that all
6573 applications interpret a keyboard event the same way, all
6574 programs in the Debian distribution must be configured to
6575 comply with the following guidelines.
6579 The following keys must have the specified interpretations:
6582 <tag><tt><--</tt></tag>
6583 <item>delete the character to the left of the cursor</item>
6585 <tag><tt>Delete</tt></tag>
6586 <item>delete the character to the right of the cursor</item>
6588 <tag><tt>Control+H</tt></tag>
6589 <item>emacs: the help prefix</item>
6592 The interpretation of any keyboard events should be
6593 independent of the terminal that is used, be it a virtual
6594 console, an X terminal emulator, an rlogin/telnet session,
6599 The following list explains how the different programs
6600 should be set up to achieve this:
6606 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6610 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6614 X translations are set up to make
6615 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6616 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6617 is the vt220 escape code for the "delete character"
6618 key). This must be done by loading the X resources
6619 using <prgn>xrdb</prgn> on all local X displays, not
6620 using the application defaults, so that the
6621 translation resources used correspond to the
6622 <prgn>xmodmap</prgn> settings.
6626 The Linux console is configured to make
6627 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6628 generate <tt>ESC [ 3 ~</tt>.
6632 X applications are configured so that <tt><</tt>
6633 deletes left, and <tt>Delete</tt> deletes right. Motif
6634 applications already work like this.
6638 Terminals should have <tt>stty erase ^?</tt> .
6642 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6643 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6644 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6648 Emacs is programmed to map <tt>KB_Backspace</tt> or
6649 the <tt>stty erase</tt> character to
6650 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6651 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6652 <tt>^H</tt> to <tt>help</tt> as always.
6656 Other applications use the <tt>stty erase</tt>
6657 character and <tt>kdch1</tt> for the two delete keys,
6658 with ASCII DEL being "delete previous character" and
6659 <tt>kdch1</tt> being "delete character under
6667 This will solve the problem except for the following
6674 Some terminals have a <tt><--</tt> key that cannot
6675 be made to produce anything except <tt>^H</tt>. On
6676 these terminals Emacs help will be unavailable on
6677 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6678 character takes precedence in Emacs, and has been set
6679 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6680 available) can be used instead.
6684 Some operating systems use <tt>^H</tt> for <tt>stty
6685 erase</tt>. However, modern telnet versions and all
6686 rlogin versions propagate <tt>stty</tt> settings, and
6687 almost all UNIX versions honour <tt>stty erase</tt>.
6688 Where the <tt>stty</tt> settings are not propagated
6689 correctly, things can be made to work by using
6690 <tt>stty</tt> manually.
6694 Some systems (including previous Debian versions) use
6695 <prgn>xmodmap</prgn> to arrange for both
6696 <tt><--</tt> and <tt>Delete</tt> to generate
6697 <tt>KB_Delete</tt>. We can change the behavior of
6698 their X clients using the same X resources that we use
6699 to do it for our own clients, or configure our clients
6700 using their resources when things are the other way
6701 around. On displays configured like this
6702 <tt>Delete</tt> will not work, but <tt><--</tt>
6707 Some operating systems have different <tt>kdch1</tt>
6708 settings in their <tt>terminfo</tt> database for
6709 <tt>xterm</tt> and others. On these systems the
6710 <tt>Delete</tt> key will not work correctly when you
6711 log in from a system conforming to our policy, but
6712 <tt><--</tt> will.
6719 <heading>Environment variables</heading>
6722 A program must not depend on environment variables to get
6723 reasonable defaults. (That's because these environment
6724 variables would have to be set in a system-wide
6725 configuration file like <file>/etc/profile</file>, which is not
6726 supported by all shells.)
6730 If a program usually depends on environment variables for its
6731 configuration, the program should be changed to fall back to
6732 a reasonable default configuration if these environment
6733 variables are not present. If this cannot be done easily
6734 (e.g., if the source code of a non-free program is not
6735 available), the program must be replaced by a small
6736 "wrapper" shell script which sets the environment variables
6737 if they are not already defined, and calls the original program.
6741 Here is an example of a wrapper script for this purpose:
6743 <example compact="compact">
6745 BAR=${BAR:-/var/lib/fubar}
6747 exec /usr/lib/foo/foo "$@"
6752 Furthermore, as <file>/etc/profile</file> is a configuration
6753 file of the <prgn>base-files</prgn> package, other packages must
6754 not put any environment variables or other commands into that
6759 <sect id="doc-base">
6760 <heading>Registering Documents using doc-base</heading>
6763 The <package>doc-base</package> package implements a
6764 flexible mechanism for handling and presenting
6765 documentation. The recommended practice is for every Debian
6766 package that provides online documentation (other than just
6767 manual pages) to register these documents with
6768 <package>doc-base</package> by installing a
6769 <package>doc-base</package> control file via the
6770 <prgn/install-docs/ script at installation time and
6771 de-register the manuals again when the package is removed.
6774 Please refer to the documentation that comes with the
6775 <package>doc-base</package> package for information and
6784 <heading>Files</heading>
6787 <heading>Binaries</heading>
6790 Two different packages must not install programs with
6791 different functionality but with the same filenames. (The
6792 case of two programs having the same functionality but
6793 different implementations is handled via "alternatives" or
6794 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6795 <ref id="conflicts"> respectively.) If this case happens,
6796 one of the programs must be renamed. The maintainers should
6797 report this to the <tt>debian-devel</tt> mailing list and
6798 try to find a consensus about which program will have to be
6799 renamed. If a consensus cannot be reached, <em>both</em>
6800 programs must be renamed.
6804 By default, when a package is being built, any binaries
6805 created should include debugging information, as well as
6806 being compiled with optimization. You should also turn on
6807 as many reasonable compilation warnings as possible; this
6808 makes life easier for porters, who can then look at build
6809 logs for possible problems. For the C programming language,
6810 this means the following compilation parameters should be
6812 <example compact="compact">
6814 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6816 INSTALL = install -s # (or use strip on the files in debian/tmp)
6821 Note that by default all installed binaries should be stripped,
6822 either by using the <tt>-s</tt> flag to
6823 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6824 the binaries after they have been copied into
6825 <file>debian/tmp</file> but before the tree is made into a
6830 Although binaries in the build tree should be compiled with
6831 debugging information by default, it can often be difficult to
6832 debug programs if they are also subjected to compiler
6833 optimization. For this reason, it is recommended to support the
6834 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6835 (see <ref id="debianrules-options">). This variable can contain
6836 several flags to change how a package is compiled and built.
6840 It is up to the package maintainer to decide what
6841 compilation options are best for the package. Certain
6842 binaries (such as computationally-intensive programs) will
6843 function better with certain flags (<tt>-O3</tt>, for
6844 example); feel free to use them. Please use good judgment
6845 here. Don't use flags for the sake of it; only use them
6846 if there is good reason to do so. Feel free to override
6847 the upstream author's ideas about which compilation
6848 options are best: they are often inappropriate for our
6854 <sect id="libraries">
6855 <heading>Libraries</heading>
6858 If the package is <strong>architecture: any</strong>, then
6859 the shared library compilation and linking flags must have
6860 <tt>-fPIC</tt>, or the package shall not build on some of
6861 the supported architectures<footnote>
6863 If you are using GCC, <tt>-fPIC</tt> produces code with
6864 relocatable position independent code, which is required for
6865 most architectures to create a shared library, with i386 and
6866 perhaps some others where non position independent code is
6867 permitted in a shared library.
6870 Position independent code may have a performance penalty,
6871 especially on <tt>i386</tt>. However, in most cases the
6872 speed penalty must be measured against the memory wasted on
6873 the few architectures where non position independent code is
6876 </footnote>. Any exception to this rule must be discussed on
6877 the mailing list <em>debian-devel@lists.debian.org</em>, and
6878 a rough consensus obtained. The reasons for not compiling
6879 with <tt>-fPIC</tt> flag must be recorded in the file
6880 <tt>README.Debian</tt>, and care must be taken to either
6881 restrict the architecture or arrange for <tt>-fPIC</tt> to
6882 be used on architectures where it is required.<footnote>
6884 Some of the reasons why this might be required is if the
6885 library contains hand crafted assembly code that is not
6886 relocatable, the speed penalty is excessive for compute
6887 intensive libs, and similar reasons.
6892 As to the static libraries, the common case is not to have
6893 relocatable code, since there is no benefit, unless in specific
6894 cases; therefore the static version must not be compiled
6895 with the <tt>-fPIC</tt> flag. Any exception to this rule
6896 should be discussed on the mailing list
6897 <em>debian-devel@lists.debian.org</em>, and the reasons for
6898 compiling with the <tt>-fPIC</tt> flag must be recorded in
6899 the file <tt>README.Debian</tt>. <footnote>
6901 Some of the reasons for linking static libraries with
6902 the <tt>-fPIC</tt> flag are if, for example, one needs a
6903 Perl API for a library that is under rapid development,
6904 and has an unstable API, so shared libraries are
6905 pointless at this phase of the library's development. In
6906 that case, since Perl needs a library with relocatable
6907 code, it may make sense to create a static library with
6908 relocatable code. Another reason cited is if you are
6909 distilling various libraries into a common shared
6910 library, like <tt>mklibs</tt> does in the Debian
6916 In other words, if both a shared and a static library is
6917 being built, each source unit (<tt>*.c</tt>, for example,
6918 for C files) will need to be compiled twice, for the normal
6922 You must specify the gcc option <tt>-D_REENTRANT</tt>
6923 when building a library (either static or shared) to make
6924 the library compatible with LinuxThreads.
6928 Although not enforced by the build tools, shared libraries
6929 must be linked against all libraries that they use symbols from
6930 in the same way that binaries are. This ensures the correct
6931 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6932 system and guarantees that all libraries can be safely opened
6933 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6934 option <tt>-Wl,-z,defs</tt> when building a shared library.
6935 Since this option enforces symbol resolution at build time,
6936 a missing library reference will be caught early as a fatal
6941 All installed shared libraries should be stripped with
6942 <example compact="compact">
6943 strip --strip-unneeded <var>your-lib</var>
6945 (The option <tt>--strip-unneeded</tt> makes
6946 <prgn>strip</prgn> remove only the symbols which aren't
6947 needed for relocation processing.) Shared libraries can
6948 function perfectly well when stripped, since the symbols for
6949 dynamic linking are in a separate part of the ELF object
6951 You might also want to use the options
6952 <tt>--remove-section=.comment</tt> and
6953 <tt>--remove-section=.note</tt> on both shared libraries
6954 and executables, and <tt>--strip-debug</tt> on static
6960 Note that under some circumstances it may be useful to
6961 install a shared library unstripped, for example when
6962 building a separate package to support debugging.
6966 Shared object files (often <file>.so</file> files) that are not
6967 public libraries, that is, they are not meant to be linked
6968 to by third party executables (binaries of other packages),
6969 should be installed in subdirectories of the
6970 <file>/usr/lib</file> directory. Such files are exempt from the
6971 rules that govern ordinary shared libraries, except that
6972 they must not be installed executable and should be
6974 A common example are the so-called "plug-ins",
6975 internal shared objects that are dynamically loaded by
6976 programs using <manref name="dlopen" section="3">.
6981 Packages containing shared libraries that may be linked to
6982 by other packages' binaries, but which for some
6983 <em>compelling</em> reason can not be installed in
6984 <file>/usr/lib</file> directory, may install the shared library
6985 files in subdirectories of the <file>/usr/lib</file> directory,
6986 in which case they should arrange to add that directory in
6987 <file>/etc/ld.so.conf</file> in the package's post-installation
6988 script, and remove it in the package's post-removal script.
6992 An ever increasing number of packages are using
6993 <prgn>libtool</prgn> to do their linking. The latest GNU
6994 libtools (>= 1.3a) can take advantage of the metadata in the
6995 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6996 files). The main advantage of <prgn>libtool</prgn>'s
6997 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6998 store and subsequently access metadata with respect to the
6999 libraries it builds. <prgn>libtool</prgn> will search for
7000 those files, which contain a lot of useful information about
7001 a library (such as library dependency information for static
7002 linking). Also, they're <em>essential</em> for programs
7003 using <tt>libltdl</tt>.<footnote>
7004 Although <prgn>libtool</prgn> is fully capable of
7005 linking against shared libraries which don't have
7006 <tt>.la</tt> files, as it is a mere shell script it can
7007 add considerably to the build time of a
7008 <prgn>libtool</prgn>-using package if that shell script
7009 has to derive all this information from first principles
7010 for each library every time it is linked. With the
7011 advent of <prgn>libtool</prgn> version 1.4 (and to a
7012 lesser extent <prgn>libtool</prgn> version 1.3), the
7013 <file>.la</file> files also store information about
7014 inter-library dependencies which cannot necessarily be
7015 derived after the <file>.la</file> file is deleted.
7020 Packages that use <prgn>libtool</prgn> to create shared
7021 libraries should include the <file>.la</file> files in the
7022 <tt>-dev</tt> package, unless the package relies on
7023 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7024 the <tt>.la</tt> files must go in the run-time library
7029 You must make sure that you use only released versions of
7030 shared libraries to build your packages; otherwise other
7031 users will not be able to run your binaries
7032 properly. Producing source packages that depend on
7033 unreleased compilers is also usually a bad
7040 <heading>Shared libraries</heading>
7042 This section has moved to <ref id="sharedlibs">.
7048 <heading>Scripts</heading>
7051 All command scripts, including the package maintainer
7052 scripts inside the package and used by <prgn>dpkg</prgn>,
7053 should have a <tt>#!</tt> line naming the shell to be used
7058 In the case of Perl scripts this should be
7059 <tt>#!/usr/bin/perl</tt>.
7063 When scripts are installed into a directory in the system
7064 PATH, the script name should not include an extension such
7065 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7066 language currently used to implement it.
7069 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7070 should almost certainly start with <tt>set -e</tt> so that
7071 errors are detected. Every script should use
7072 <tt>set -e</tt> or check the exit status of <em>every</em>
7077 Scripts may assume that <file>/bin/sh</file> implements the
7078 SUSv3 Shell Command Language<footnote>
7079 Single UNIX Specification, version 3, which is also IEEE
7080 1003.1-2004 (POSIX), and is available on the World Wide Web
7081 from <url id="http://www.unix.org/version3/online.html"
7082 name="The Open Group"> after free
7083 registration.</footnote>
7084 plus the following additional features not mandated by
7086 These features are in widespread use in the Linux community
7087 and are implemented in all of bash, dash, and ksh, the most
7088 common shells users may wish to use as <file>/bin/sh</file>.
7091 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7092 must not generate a newline.</item>
7093 <item><tt>test</tt>, if implemented as a shell built-in, must
7094 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7096 <item><tt>local</tt> to create a scoped variable must be
7097 supported, including listing multiple variables in a single
7098 local command and assigning a value to a variable at the
7099 same time as localizing it. <tt>local</tt> may or
7100 may not preserve the variable value from an outer scope if
7101 no assignment is present. Uses such as:
7105 # ... use a, b, c, d ...
7108 must be supported and must set the value of <tt>c</tt> to
7112 If a shell script requires non-SUSv3 features from the shell
7113 interpreter other than those listed above, the appropriate shell
7114 must be specified in the first line of the script (e.g.,
7115 <tt>#!/bin/bash</tt>) and the package must depend on the package
7116 providing the shell (unless the shell package is marked
7117 "Essential", as in the case of <prgn>bash</prgn>).
7121 You may wish to restrict your script to SUSv3 features plus the
7122 above set when possible so that it may use <file>/bin/sh</file>
7123 as its interpreter. If your script works with <prgn>dash</prgn>
7124 (originally called <prgn>ash</prgn>), it probably complies with
7125 the above requirements, but if you are in doubt, use
7126 <file>/bin/bash</file>.
7130 Perl scripts should check for errors when making any
7131 system calls, including <tt>open</tt>, <tt>print</tt>,
7132 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7136 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7137 scripting languages. See <em>Csh Programming Considered
7138 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7139 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7140 If an upstream package comes with <prgn>csh</prgn> scripts
7141 then you must make sure that they start with
7142 <tt>#!/bin/csh</tt> and make your package depend on the
7143 <prgn>c-shell</prgn> virtual package.
7147 Any scripts which create files in world-writeable
7148 directories (e.g., in <file>/tmp</file>) must use a
7149 mechanism which will fail atomically if a file with the same
7150 name already exists.
7154 The Debian base system provides the <prgn>tempfile</prgn>
7155 and <prgn>mktemp</prgn> utilities for use by scripts for
7162 <heading>Symbolic links</heading>
7165 In general, symbolic links within a top-level directory
7166 should be relative, and symbolic links pointing from one
7167 top-level directory into another should be absolute. (A
7168 top-level directory is a sub-directory of the root
7169 directory <file>/</file>.)
7173 In addition, symbolic links should be specified as short as
7174 possible, i.e., link targets like <file>foo/../bar</file> are
7179 Note that when creating a relative link using
7180 <prgn>ln</prgn> it is not necessary for the target of the
7181 link to exist relative to the working directory you're
7182 running <prgn>ln</prgn> from, nor is it necessary to change
7183 directory to the directory where the link is to be made.
7184 Simply include the string that should appear as the target
7185 of the link (this will be a pathname relative to the
7186 directory in which the link resides) as the first argument
7191 For example, in your <prgn>Makefile</prgn> or
7192 <file>debian/rules</file>, you can do things like:
7193 <example compact="compact">
7194 ln -fs gcc $(prefix)/bin/cc
7195 ln -fs gcc debian/tmp/usr/bin/cc
7196 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7197 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7202 A symbolic link pointing to a compressed file should always
7203 have the same file extension as the referenced file. (For
7204 example, if a file <file>foo.gz</file> is referenced by a
7205 symbolic link, the filename of the link has to end with
7206 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7211 <heading>Device files</heading>
7214 Packages must not include device files in the package file
7219 If a package needs any special device files that are not
7220 included in the base system, it must call
7221 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7222 after notifying the user<footnote>
7223 This notification could be done via a (low-priority)
7224 debconf message, or an echo (printf) statement.
7229 Packages must not remove any device files in the
7230 <prgn>postrm</prgn> or any other script. This is left to the
7231 system administrator.
7235 Debian uses the serial devices
7236 <file>/dev/ttyS*</file>. Programs using the old
7237 <file>/dev/cu*</file> devices should be changed to use
7238 <file>/dev/ttyS*</file>.
7242 <sect id="config-files">
7243 <heading>Configuration files</heading>
7246 <heading>Definitions</heading>
7250 <tag>configuration file</tag>
7252 A file that affects the operation of a program, or
7253 provides site- or host-specific information, or
7254 otherwise customizes the behavior of a program.
7255 Typically, configuration files are intended to be
7256 modified by the system administrator (if needed or
7257 desired) to conform to local policy or to provide
7258 more useful site-specific behavior.
7261 <tag><tt>conffile</tt></tag>
7263 A file listed in a package's <tt>conffiles</tt>
7264 file, and is treated specially by <prgn>dpkg</prgn>
7265 (see <ref id="configdetails">).
7271 The distinction between these two is important; they are
7272 not interchangeable concepts. Almost all
7273 <tt>conffile</tt>s are configuration files, but many
7274 configuration files are not <tt>conffiles</tt>.
7278 As noted elsewhere, <file>/etc/init.d</file> scripts,
7279 <file>/etc/default</file> files, scripts installed in
7280 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7281 configuration installed in <file>/etc/cron.d</file> must be
7282 treated as configuration files. In general, any script that
7283 embeds configuration information is de-facto a configuration
7284 file and should be treated as such.
7289 <heading>Location</heading>
7292 Any configuration files created or used by your package
7293 must reside in <file>/etc</file>. If there are several,
7294 consider creating a subdirectory of <file>/etc</file>
7295 named after your package.
7299 If your package creates or uses configuration files
7300 outside of <file>/etc</file>, and it is not feasible to modify
7301 the package to use <file>/etc</file> directly, put the files
7302 in <file>/etc</file> and create symbolic links to those files
7303 from the location that the package requires.
7308 <heading>Behavior</heading>
7311 Configuration file handling must conform to the following
7313 <list compact="compact">
7315 local changes must be preserved during a package
7319 configuration files must be preserved when the
7320 package is removed, and only deleted when the
7327 The easy way to achieve this behavior is to make the
7328 configuration file a <tt>conffile</tt>. This is
7329 appropriate only if it is possible to distribute a default
7330 version that will work for most installations, although
7331 some system administrators may choose to modify it. This
7332 implies that the default version will be part of the
7333 package distribution, and must not be modified by the
7334 maintainer scripts during installation (or at any other
7339 In order to ensure that local changes are preserved
7340 correctly, no package may contain or make hard links to
7341 conffiles.<footnote>
7342 Rationale: There are two problems with hard links.
7343 The first is that some editors break the link while
7344 editing one of the files, so that the two files may
7345 unwittingly become unlinked and different. The second
7346 is that <prgn>dpkg</prgn> might break the hard link
7347 while upgrading <tt>conffile</tt>s.
7352 The other way to do it is via the maintainer scripts. In
7353 this case, the configuration file must not be listed as a
7354 <tt>conffile</tt> and must not be part of the package
7355 distribution. If the existence of a file is required for
7356 the package to be sensibly configured it is the
7357 responsibility of the package maintainer to provide
7358 maintainer scripts which correctly create, update and
7359 maintain the file and remove it on purge. (See <ref
7360 id="maintainerscripts"> for more information.) These
7361 scripts must be idempotent (i.e., must work correctly if
7362 <prgn>dpkg</prgn> needs to re-run them due to errors
7363 during installation or removal), must cope with all the
7364 variety of ways <prgn>dpkg</prgn> can call maintainer
7365 scripts, must not overwrite or otherwise mangle the user's
7366 configuration without asking, must not ask unnecessary
7367 questions (particularly during upgrades), and must
7368 otherwise be good citizens.
7372 The scripts are not required to configure every possible
7373 option for the package, but only those necessary to get
7374 the package running on a given system. Ideally the
7375 sysadmin should not have to do any configuration other
7376 than that done (semi-)automatically by the
7377 <prgn>postinst</prgn> script.
7381 A common practice is to create a script called
7382 <file><var>package</var>-configure</file> and have the
7383 package's <prgn>postinst</prgn> call it if and only if the
7384 configuration file does not already exist. In certain
7385 cases it is useful for there to be an example or template
7386 file which the maintainer scripts use. Such files should
7387 be in <file>/usr/share/<var>package</var></file> or
7388 <file>/usr/lib/<var>package</var></file> (depending on whether
7389 they are architecture-independent or not). There should
7390 be symbolic links to them from
7391 <file>/usr/share/doc/<var>package</var>/examples</file> if
7392 they are examples, and should be perfectly ordinary
7393 <prgn>dpkg</prgn>-handled files (<em>not</em>
7394 configuration files).
7398 These two styles of configuration file handling must
7399 not be mixed, for that way lies madness:
7400 <prgn>dpkg</prgn> will ask about overwriting the file
7401 every time the package is upgraded.
7406 <heading>Sharing configuration files</heading>
7409 Packages which specify the same file as a
7410 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7411 with each other. (This is an instance of the general rule
7412 about not sharing files. Note that neither alternatives
7413 nor diversions are likely to be appropriate in this case;
7414 in particular, <prgn>dpkg</prgn> does not handle diverted
7415 <tt>conffile</tt>s well.)
7419 The maintainer scripts must not alter a <tt>conffile</tt>
7420 of <em>any</em> package, including the one the scripts
7425 If two or more packages use the same configuration file
7426 and it is reasonable for both to be installed at the same
7427 time, one of these packages must be defined as
7428 <em>owner</em> of the configuration file, i.e., it will be
7429 the package which handles that file as a configuration
7430 file. Other packages that use the configuration file must
7431 depend on the owning package if they require the
7432 configuration file to operate. If the other package will
7433 use the configuration file if present, but is capable of
7434 operating without it, no dependency need be declared.
7438 If it is desirable for two or more related packages to
7439 share a configuration file <em>and</em> for all of the
7440 related packages to be able to modify that configuration
7441 file, then the following should be done:
7442 <enumlist compact="compact">
7444 One of the related packages (the "owning" package)
7445 will manage the configuration file with maintainer
7446 scripts as described in the previous section.
7449 The owning package should also provide a program
7450 that the other packages may use to modify the
7454 The related packages must use the provided program
7455 to make any desired modifications to the
7456 configuration file. They should either depend on
7457 the core package to guarantee that the configuration
7458 modifier program is available or accept gracefully
7459 that they cannot modify the configuration file if it
7460 is not. (This is in addition to the fact that the
7461 configuration file may not even be present in the
7468 Sometimes it's appropriate to create a new package which
7469 provides the basic infrastructure for the other packages
7470 and which manages the shared configuration files. (The
7471 <tt>sgml-base</tt> package is a good example.)
7476 <heading>User configuration files ("dotfiles")</heading>
7479 The files in <file>/etc/skel</file> will automatically be
7480 copied into new user accounts by <prgn>adduser</prgn>.
7481 No other program should reference the files in
7482 <file>/etc/skel</file>.
7486 Therefore, if a program needs a dotfile to exist in
7487 advance in <file>$HOME</file> to work sensibly, that dotfile
7488 should be installed in <file>/etc/skel</file> and treated as a
7493 However, programs that require dotfiles in order to
7494 operate sensibly are a bad thing, unless they do create
7495 the dotfiles themselves automatically.
7499 Furthermore, programs should be configured by the Debian
7500 default installation to behave as closely to the upstream
7501 default behavior as possible.
7505 Therefore, if a program in a Debian package needs to be
7506 configured in some way in order to operate sensibly, that
7507 should be done using a site-wide configuration file placed
7508 in <file>/etc</file>. Only if the program doesn't support a
7509 site-wide default configuration and the package maintainer
7510 doesn't have time to add it may a default per-user file be
7511 placed in <file>/etc/skel</file>.
7515 <file>/etc/skel</file> should be as empty as we can make it.
7516 This is particularly true because there is no easy (or
7517 necessarily desirable) mechanism for ensuring that the
7518 appropriate dotfiles are copied into the accounts of
7519 existing users when a package is installed.
7525 <heading>Log files</heading>
7527 Log files should usually be named
7528 <file>/var/log/<var>package</var>.log</file>. If you have many
7529 log files, or need a separate directory for permission
7530 reasons (<file>/var/log</file> is writable only by
7531 <file>root</file>), you should usually create a directory named
7532 <file>/var/log/<var>package</var></file> and place your log
7537 Log files must be rotated occasionally so that they don't
7538 grow indefinitely; the best way to do this is to drop a log
7539 rotation configuration file into the directory
7540 <file>/etc/logrotate.d</file> and use the facilities provided by
7541 logrotate.<footnote>
7543 The traditional approach to log files has been to set up
7544 <em>ad hoc</em> log rotation schemes using simple shell
7545 scripts and cron. While this approach is highly
7546 customizable, it requires quite a lot of sysadmin work.
7547 Even though the original Debian system helped a little
7548 by automatically installing a system which can be used
7549 as a template, this was deemed not enough.
7553 The use of <prgn>logrotate</prgn>, a program developed
7554 by Red Hat, is better, as it centralizes log management.
7555 It has both a configuration file
7556 (<file>/etc/logrotate.conf</file>) and a directory where
7557 packages can drop their individual log rotation
7558 configurations (<file>/etc/logrotate.d</file>).
7561 Here is a good example for a logrotate config
7562 file (for more information see <manref name="logrotate"
7564 <example compact="compact">
7565 /var/log/foo/*.log {
7570 /etc/init.d/foo force-reload
7574 This rotates all files under <file>/var/log/foo</file>, saves 12
7575 compressed generations, and forces the daemon to reload its
7576 configuration information after the log rotation.
7580 Log files should be removed when the package is
7581 purged (but not when it is only removed). This should be
7582 done by the <prgn>postrm</prgn> script when it is called
7583 with the argument <tt>purge</tt> (see <ref
7584 id="removedetails">).
7589 <heading>Permissions and owners</heading>
7592 The rules in this section are guidelines for general use.
7593 If necessary you may deviate from the details below.
7594 However, if you do so you must make sure that what is done
7595 is secure and you should try to be as consistent as possible
7596 with the rest of the system. You should probably also
7597 discuss it on <prgn>debian-devel</prgn> first.
7601 Files should be owned by <tt>root:root</tt>, and made
7602 writable only by the owner and universally readable (and
7603 executable, if appropriate), that is mode 644 or 755.
7607 Directories should be mode 755 or (for group-writability)
7608 mode 2775. The ownership of the directory should be
7609 consistent with its mode: if a directory is mode 2775, it
7610 should be owned by the group that needs write access to
7613 When a package is upgraded, and the owner or permissions
7614 of a file included in the package has changed, dpkg
7615 arranges for the ownership and permissions to be
7616 correctly set upon installation. However, this does not
7617 extend to directories; the permissions and ownership of
7618 directories already on the system does not change on
7619 install or upgrade of packages. This makes sense, since
7620 otherwise common directories like <tt>/usr</tt> would
7621 always be in flux. To correctly change permissions of a
7622 directory the package owns, explicit action is required,
7623 usually in the <tt>postinst</tt> script. Care must be
7624 taken to handle downgrades as well, in that case.
7631 Setuid and setgid executables should be mode 4755 or 2755
7632 respectively, and owned by the appropriate user or group.
7633 They should not be made unreadable (modes like 4711 or
7634 2711 or even 4111); doing so achieves no extra security,
7635 because anyone can find the binary in the freely available
7636 Debian package; it is merely inconvenient. For the same
7637 reason you should not restrict read or execute permissions
7638 on non-set-id executables.
7642 Some setuid programs need to be restricted to particular
7643 sets of users, using file permissions. In this case they
7644 should be owned by the uid to which they are set-id, and by
7645 the group which should be allowed to execute them. They
7646 should have mode 4754; again there is no point in making
7647 them unreadable to those users who must not be allowed to
7652 It is possible to arrange that the system administrator can
7653 reconfigure the package to correspond to their local
7654 security policy by changing the permissions on a binary:
7655 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7656 described below.<footnote>
7657 Ordinary files installed by <prgn>dpkg</prgn> (as
7658 opposed to <tt>conffile</tt>s and other similar objects)
7659 normally have their permissions reset to the distributed
7660 permissions when the package is reinstalled. However,
7661 the use of <prgn>dpkg-statoverride</prgn> overrides this
7662 default behavior. If you use this method, you should
7663 remember to describe <prgn>dpkg-statoverride</prgn> in
7664 the package documentation; being a relatively new
7665 addition to Debian, it is probably not yet well-known.
7667 Another method you should consider is to create a group for
7668 people allowed to use the program(s) and make any setuid
7669 executables executable only by that group.
7673 If you need to create a new user or group for your package
7674 there are two possibilities. Firstly, you may need to
7675 make some files in the binary package be owned by this
7676 user or group, or you may need to compile the user or
7677 group id (rather than just the name) into the binary
7678 (though this latter should be avoided if possible, as in
7679 this case you need a statically allocated id).</p>
7682 If you need a statically allocated id, you must ask for a
7683 user or group id from the <tt>base-passwd</tt> maintainer,
7684 and must not release the package until you have been
7685 allocated one. Once you have been allocated one you must
7686 either make the package depend on a version of the
7687 <tt>base-passwd</tt> package with the id present in
7688 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7689 your package to create the user or group itself with the
7690 correct id (using <tt>adduser</tt>) in its
7691 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7692 the <prgn>postinst</prgn> is to be preferred if it is
7693 possible, otherwise a pre-dependency will be needed on the
7694 <tt>adduser</tt> package.)
7698 On the other hand, the program might be able to determine
7699 the uid or gid from the user or group name at runtime, so
7700 that a dynamically allocated id can be used. In this case
7701 you should choose an appropriate user or group name,
7702 discussing this on <prgn>debian-devel</prgn> and checking
7703 with the <package/base-passwd/ maintainer that it is unique and that
7704 they do not wish you to use a statically allocated id
7705 instead. When this has been checked you must arrange for
7706 your package to create the user or group if necessary using
7707 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7708 <prgn>postinst</prgn> script (again, the latter is to be
7709 preferred if it is possible).
7713 Note that changing the numeric value of an id associated
7714 with a name is very difficult, and involves searching the
7715 file system for all appropriate files. You need to think
7716 carefully whether a static or dynamic id is required, since
7717 changing your mind later will cause problems.
7720 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7722 This section is not intended as policy, but as a
7723 description of the use of <prgn>dpkg-statoverride</prgn>.
7727 If a system administrator wishes to have a file (or
7728 directory or other such thing) installed with owner and
7729 permissions different from those in the distributed Debian
7730 package, they can use the <prgn>dpkg-statoverride</prgn>
7731 program to instruct <prgn>dpkg</prgn> to use the different
7732 settings every time the file is installed. Thus the
7733 package maintainer should distribute the files with their
7734 normal permissions, and leave it for the system
7735 administrator to make any desired changes. For example, a
7736 daemon which is normally required to be setuid root, but
7737 in certain situations could be used without being setuid,
7738 should be installed setuid in the <tt>.deb</tt>. Then the
7739 local system administrator can change this if they wish.
7740 If there are two standard ways of doing it, the package
7741 maintainer can use <tt>debconf</tt> to find out the
7742 preference, and call <prgn>dpkg-statoverride</prgn> in the
7743 maintainer script if necessary to accommodate the system
7744 administrator's choice. Care must be taken during
7745 upgrades to not override an existing setting.
7749 Given the above, <prgn>dpkg-statoverride</prgn> is
7750 essentially a tool for system administrators and would not
7751 normally be needed in the maintainer scripts. There is
7752 one type of situation, though, where calls to
7753 <prgn>dpkg-statoverride</prgn> would be needed in the
7754 maintainer scripts, and that involves packages which use
7755 dynamically allocated user or group ids. In such a
7756 situation, something like the following idiom can be very
7757 helpful in the package's <prgn>postinst</prgn>, where
7758 <tt>sysuser</tt> is a dynamically allocated id:
7760 for i in /usr/bin/foo /usr/sbin/bar
7762 # only do something when no setting exists
7763 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7765 #include: debconf processing, question about foo and bar
7766 if [ "$RET" = "true" ] ; then
7767 dpkg-statoverride --update --add sysuser root 4755 $i
7772 The corresponding <tt>dpkg-statoverride --remove</tt>
7773 calls can then be made unconditionally when the package is
7781 <chapt id="customized-programs">
7782 <heading>Customized programs</heading>
7784 <sect id="arch-spec">
7785 <heading>Architecture specification strings</heading>
7788 If a program needs to specify an <em>architecture specification
7789 string</em> in some place, it should select one of the
7790 strings provided by <tt>dpkg-architecture -L</tt>. The
7791 strings are in the format
7792 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7793 is sometimes elided, as when the OS is Linux.<footnote>
7794 <p>Currently, the strings are:
7795 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7796 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7797 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7798 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7799 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7800 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7801 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7802 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7803 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7804 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7805 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7806 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7807 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7808 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7809 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7810 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7811 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7812 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7813 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7814 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7815 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7816 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7817 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7818 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7819 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7820 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7821 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7822 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7823 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7824 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7825 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7826 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7827 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7828 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7829 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7830 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7831 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7837 Note that we don't want to use
7838 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7839 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7840 since this would make our programs incompatible with other
7841 Linux distributions. We also don't use something like
7842 <tt><var>arch</var>-unknown-linux</tt>, since the
7843 <tt>unknown</tt> does not look very good.
7848 <heading>Daemons</heading>
7851 The configuration files <file>/etc/services</file>,
7852 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7853 by the <prgn>netbase</prgn> package and must not be modified
7858 If a package requires a new entry in one of these files, the
7859 maintainer should get in contact with the
7860 <prgn>netbase</prgn> maintainer, who will add the entries
7861 and release a new version of the <prgn>netbase</prgn>
7866 The configuration file <file>/etc/inetd.conf</file> must not be
7867 modified by the package's scripts except via the
7868 <prgn>update-inetd</prgn> script or the
7869 <file>DebianNet.pm</file> Perl module. See their documentation
7870 for details on how to add entries.
7874 If a package wants to install an example entry into
7875 <file>/etc/inetd.conf</file>, the entry must be preceded with
7876 exactly one hash character (<tt>#</tt>). Such lines are
7877 treated as "commented out by user" by the
7878 <prgn>update-inetd</prgn> script and are not changed or
7879 activated during package updates.
7884 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7888 Some programs need to create pseudo-ttys. This should be done
7889 using Unix98 ptys if the C library supports it. The resulting
7890 program must not be installed setuid root, unless that
7891 is required for other functionality.
7895 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7896 <file>/var/log/lastlog</file> must be installed writable by
7897 group <tt>utmp</tt>. Programs which need to modify those
7898 files must be installed setgid <tt>utmp</tt>.
7903 <heading>Editors and pagers</heading>
7906 Some programs have the ability to launch an editor or pager
7907 program to edit or display a text document. Since there are
7908 lots of different editors and pagers available in the Debian
7909 distribution, the system administrator and each user should
7910 have the possibility to choose their preferred editor and
7915 In addition, every program should choose a good default
7916 editor/pager if none is selected by the user or system
7921 Thus, every program that launches an editor or pager must
7922 use the EDITOR or PAGER environment variable to determine
7923 the editor or pager the user wishes to use. If these
7924 variables are not set, the programs <file>/usr/bin/editor</file>
7925 and <file>/usr/bin/pager</file> should be used, respectively.
7929 These two files are managed through the <prgn>dpkg</prgn>
7930 "alternatives" mechanism. Thus every package providing an
7931 editor or pager must call the
7932 <prgn>update-alternatives</prgn> script to register these
7937 If it is very hard to adapt a program to make use of the
7938 EDITOR or PAGER variables, that program may be configured to
7939 use <file>/usr/bin/sensible-editor</file> and
7940 <file>/usr/bin/sensible-pager</file> as the editor or pager
7941 program respectively. These are two scripts provided in the
7942 Debian base system that check the EDITOR and PAGER variables
7943 and launch the appropriate program, and fall back to
7944 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7945 variable is not set.
7949 A program may also use the VISUAL environment variable to
7950 determine the user's choice of editor. If it exists, it
7951 should take precedence over EDITOR. This is in fact what
7952 <file>/usr/bin/sensible-editor</file> does.
7956 It is not required for a package to depend on
7957 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7958 package to provide such virtual packages.<footnote>
7959 The Debian base system already provides an editor and a
7965 <sect id="web-appl">
7966 <heading>Web servers and applications</heading>
7969 This section describes the locations and URLs that should
7970 be used by all web servers and web applications in the
7977 Cgi-bin executable files are installed in the
7979 <example compact="compact">
7980 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7982 and should be referred to as
7983 <example compact="compact">
7984 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7990 <p>Access to HTML documents</p>
7993 HTML documents for a package are stored in
7994 <file>/usr/share/doc/<var>package</var></file>
7995 and can be referred to as
7996 <example compact="compact">
7997 http://localhost/doc/<var>package</var>/<var>filename</var>
8002 The web server should restrict access to the document
8003 tree so that only clients on the same host can read
8004 the documents. If the web server does not support such
8005 access controls, then it should not provide access at
8006 all, or ask about providing access during installation.
8011 <p>Access to images</p>
8013 It is recommended that images for a package be stored
8014 in <tt>/usr/share/images/<var>package</var></tt> and
8015 may be referred to through an alias <tt>/images/</tt>
8018 http://localhost/images/<package>/<filename>
8025 <p>Web Document Root</p>
8028 Web Applications should try to avoid storing files in
8029 the Web Document Root. Instead they should use the
8030 /usr/share/doc/<var>package</var> directory for
8031 documents and register the Web Application via the
8032 <package>doc-base</package> package. If access to the
8033 web document root is unavoidable then use
8034 <example compact="compact">
8037 as the Document Root. This might be just a symbolic
8038 link to the location where the system administrator
8039 has put the real document root.
8042 <item><p>Providing httpd and/or httpd-cgi</p>
8044 All web servers should provide the virtual package
8045 <tt>httpd</tt>. If a web server has CGI support it should
8046 provide <tt>httpd-cgi</tt> additionally.
8049 All web applications which do not contain CGI scripts should
8050 depend on <tt>httpd</tt>, all those web applications which
8051 <tt>do</tt> contain CGI scripts, should depend on
8059 <sect id="mail-transport-agents">
8060 <heading>Mail transport, delivery and user agents</heading>
8063 Debian packages which process electronic mail, whether mail
8064 user agents (MUAs) or mail transport agents (MTAs), must
8065 ensure that they are compatible with the configuration
8066 decisions below. Failure to do this may result in lost
8067 mail, broken <tt>From:</tt> lines, and other serious brain
8072 The mail spool is <file>/var/mail</file> and the interface to
8073 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8074 the FHS). On older systems, the mail spool may be
8075 physically located in <file>/var/spool/mail</file>, but all
8076 access to the mail spool should be via the
8077 <file>/var/mail</file> symlink. The mail spool is part of the
8078 base system and not part of the MTA package.
8082 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8083 programs (such as IMAP daemons) must lock the mailbox in an
8084 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8085 be combined with dot locking. To avoid deadlocks, a program
8086 should use <tt>fcntl()</tt> first and dot locking after
8087 this, or alternatively implement the two locking methods in
8088 a non blocking way<footnote>
8089 If it is not possible to establish both locks, the
8090 system shouldn't wait for the second lock to be
8091 established, but remove the first lock, wait a (random)
8092 time, and start over locking again.
8093 </footnote>. Using the functions <tt>maillock</tt> and
8094 <tt>mailunlock</tt> provided by the
8095 <tt>liblockfile*</tt><footnote>
8096 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8097 to use these functions.
8098 </footnote> packages is the recommended way to realize this.
8102 Mailboxes are generally either mode 600 and owned by
8103 <var>user</var> or mode 660 and owned by
8104 <tt><var>user</var>:mail</tt><footnote>
8105 There are two traditional permission schemes for mail spools:
8106 mode 600 with all mail delivery done by processes running as
8107 the destination user, or mode 660 and owned by group mail with
8108 mail delivery done by a process running as a system user in
8109 group mail. Historically, Debian required mode 660 mail
8110 spools to enable the latter model, but that model has become
8111 increasingly uncommon and the principle of least privilege
8112 indicates that mail systems that use the first model should
8113 use permissions of 600. If delivery to programs is permitted,
8114 it's easier to keep the mail system secure if the delivery
8115 agent runs as the destination user. Debian Policy therefore
8116 permits either scheme.
8117 </footnote>. The local system administrator may choose a
8118 different permission scheme; packages should not make
8119 assumptions about the permission and ownership of mailboxes
8120 unless required (such as when creating a new mailbox). A MUA
8121 may remove a mailbox (unless it has nonstandard permissions) in
8122 which case the MTA or another MUA must recreate it if needed.
8126 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8127 be setgid mail to do the locking mentioned above (and
8128 must obviously avoid accessing other users' mailboxes
8129 using this privilege).</p>
8132 <file>/etc/aliases</file> is the source file for the system mail
8133 aliases (e.g., postmaster, usenet, etc.), it is the one
8134 which the sysadmin and <prgn>postinst</prgn> scripts may
8135 edit. After <file>/etc/aliases</file> is edited the program or
8136 human editing it must call <prgn>newaliases</prgn>. All MTA
8137 packages must come with a <prgn>newaliases</prgn> program,
8138 even if it does nothing, but older MTA packages did not do
8139 this so programs should not fail if <prgn>newaliases</prgn>
8140 cannot be found. Note that because of this, all MTA
8141 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8142 <tt>Replaces: mail-transport-agent</tt> control file
8147 The convention of writing <tt>forward to
8148 <var>address</var></tt> in the mailbox itself is not
8149 supported. Use a <tt>.forward</tt> file instead.</p>
8152 The <prgn>rmail</prgn> program used by UUCP
8153 for incoming mail should be <file>/usr/sbin/rmail</file>.
8154 Likewise, <prgn>rsmtp</prgn>, for receiving
8155 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8159 If your package needs to know what hostname to use on (for
8160 example) outgoing news and mail messages which are generated
8161 locally, you should use the file <file>/etc/mailname</file>. It
8162 will contain the portion after the username and <tt>@</tt>
8163 (at) sign for email addresses of users on the machine
8164 (followed by a newline).
8168 Such a package should check for the existence of this file
8169 when it is being configured. If it exists, it should be
8170 used without comment, although an MTA's configuration script
8171 may wish to prompt the user even if it finds that this file
8172 exists. If the file does not exist, the package should
8173 prompt the user for the value (preferably using
8174 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8175 as well as using it in the package's configuration. The
8176 prompt should make it clear that the name will not just be
8177 used by that package. For example, in this situation the
8178 <tt>inn</tt> package could say something like:
8179 <example compact="compact">
8180 Please enter the "mail name" of your system. This is the
8181 hostname portion of the address to be shown on outgoing
8182 news and mail messages. The default is
8183 <var>syshostname</var>, your system's host name. Mail
8184 name ["<var>syshostname</var>"]:
8186 where <var>syshostname</var> is the output of <tt>hostname
8192 <heading>News system configuration</heading>
8195 All the configuration files related to the NNTP (news)
8196 servers and clients should be located under
8197 <file>/etc/news</file>.</p>
8200 There are some configuration issues that apply to a number
8201 of news clients and server packages on the machine. These
8205 <tag><file>/etc/news/organization</file></tag>
8207 A string which should appear as the
8208 organization header for all messages posted
8209 by NNTP clients on the machine
8212 <tag><file>/etc/news/server</file></tag>
8214 Contains the FQDN of the upstream NNTP
8215 server, or localhost if the local machine is
8220 Other global files may be added as required for cross-package news
8227 <heading>Programs for the X Window System</heading>
8230 <heading>Providing X support and package priorities</heading>
8233 Programs that can be configured with support for the X
8234 Window System must be configured to do so and must declare
8235 any package dependencies necessary to satisfy their
8236 runtime requirements when using the X Window System. If
8237 such a package is of higher priority than the X packages
8238 on which it depends, it is required that either the
8239 X-specific components be split into a separate package, or
8240 that an alternative version of the package, which includes
8241 X support, be provided, or that the package's priority be
8247 <heading>Packages providing an X server</heading>
8250 Packages that provide an X server that, directly or
8251 indirectly, communicates with real input and display
8252 hardware should declare in their control data that they
8253 provide the virtual package <tt>xserver</tt>.<footnote>
8254 This implements current practice, and provides an
8255 actual policy for usage of the <tt>xserver</tt>
8256 virtual package which appears in the virtual packages
8257 list. In a nutshell, X servers that interface
8258 directly with the display and input hardware or via
8259 another subsystem (e.g., GGI) should provide
8260 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8261 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8267 <heading>Packages providing a terminal emulator</heading>
8270 Packages that provide a terminal emulator for the X Window
8271 System which meet the criteria listed below should declare
8272 in their control data that they provide the virtual
8273 package <tt>x-terminal-emulator</tt>. They should also
8274 register themselves as an alternative for
8275 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8280 To be an <tt>x-terminal-emulator</tt>, a program must:
8281 <list compact="compact">
8283 Be able to emulate a DEC VT100 terminal, or a
8284 compatible terminal.
8288 Support the command-line option <tt>-e
8289 <var>command</var></tt>, which creates a new
8290 terminal window<footnote>
8291 "New terminal window" does not necessarily mean
8292 a new top-level X window directly parented by
8293 the window manager; it could, if the terminal
8294 emulator application were so coded, be a new
8295 "view" in a multiple-document interface (MDI).
8297 and runs the specified <var>command</var>,
8298 interpreting the entirety of the rest of the command
8299 line as a command to pass straight to exec, in the
8300 manner that <tt>xterm</tt> does.
8304 Support the command-line option <tt>-T
8305 <var>title</var></tt>, which creates a new terminal
8306 window with the window title <var>title</var>.
8313 <heading>Packages providing a window manager</heading>
8316 Packages that provide a window manager should declare in
8317 their control data that they provide the virtual package
8318 <tt>x-window-manager</tt>. They should also register
8319 themselves as an alternative for
8320 <file>/usr/bin/x-window-manager</file>, with a priority
8321 calculated as follows:
8322 <list compact="compact">
8324 Start with a priority of 20.
8328 If the window manager supports the Debian menu
8329 system, add 20 points if this support is available
8330 in the package's default configuration (i.e., no
8331 configuration files belonging to the system or user
8332 have to be edited to activate the feature); if
8333 configuration files must be modified, add only 10
8339 If the window manager complies with <url
8340 id="http://www.freedesktop.org/Standards/wm-spec"
8341 name="The Window Manager Specification Project">,
8342 written by the <url id="http://www.freedesktop.org/"
8343 name="Free Desktop Group">, add 40 points.
8347 If the window manager permits the X session to be
8348 restarted using a <em>different</em> window manager
8349 (without killing the X server) in its default
8350 configuration, add 10 points; otherwise add none.
8357 <heading>Packages providing fonts</heading>
8360 Packages that provide fonts for the X Window
8362 For the purposes of Debian Policy, a "font for the X
8363 Window System" is one which is accessed via X protocol
8364 requests. Fonts for the Linux console, for PostScript
8365 renderer, or any other purpose, do not fit this
8366 definition. Any tool which makes such fonts available
8367 to the X Window System, however, must abide by this
8370 must do a number of things to ensure that they are both
8371 available without modification of the X or font server
8372 configuration, and that they do not corrupt files used by
8373 other font packages to register information about
8377 Fonts of any type supported by the X Window System
8378 must be in a separate binary package from any
8379 executables, libraries, or documentation (except
8380 that specific to the fonts shipped, such as their
8381 license information). If one or more of the fonts
8382 so packaged are necessary for proper operation of
8383 the package with which they are associated the font
8384 package may be Recommended; if the fonts merely
8385 provide an enhancement, a Suggests relationship may
8386 be used. Packages must not Depend on font
8388 This is because the X server may retrieve fonts
8389 from the local file system or over the network
8390 from an X font server; the Debian package system
8391 is empowered to deal only with the local
8397 BDF fonts must be converted to PCF fonts with the
8398 <prgn>bdftopcf</prgn> utility (available in the
8399 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8400 placed in a directory that corresponds to their
8402 <list compact="compact">
8404 100 dpi fonts must be placed in
8405 <file>/usr/share/fonts/X11/100dpi/</file>.
8409 75 dpi fonts must be placed in
8410 <file>/usr/share/fonts/X11/75dpi/</file>.
8414 Character-cell fonts, cursor fonts, and other
8415 low-resolution fonts must be placed in
8416 <file>/usr/share/fonts/X11/misc/</file>.
8422 Speedo fonts must be placed in
8423 <file>/usr/share/fonts/X11/Speedo/</file>.
8427 Type 1 fonts must be placed in
8428 <file>/usr/share/fonts/X11/Type1/</file>. If font
8429 metric files are available, they must be placed here
8434 Subdirectories of <file>/usr/share/fonts/X11/</file>
8435 other than those listed above must be neither
8436 created nor used. (The <file>PEX</file>, <file>CID</file>,
8437 and <file>cyrillic</file> directories are excepted for
8438 historical reasons, but installation of files into
8439 these directories remains discouraged.)
8443 Font packages may, instead of placing files directly
8444 in the X font directories listed above, provide
8445 symbolic links in that font directory pointing to
8446 the files' actual location in the filesystem. Such
8447 a location must comply with the FHS.
8451 Font packages should not contain both 75dpi and
8452 100dpi versions of a font. If both are available,
8453 they should be provided in separate binary packages
8454 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8455 the names of the packages containing the
8456 corresponding fonts.
8460 Fonts destined for the <file>misc</file> subdirectory
8461 should not be included in the same package as 75dpi
8462 or 100dpi fonts; instead, they should be provided in
8463 a separate package with <tt>-misc</tt> appended to
8468 Font packages must not provide the files
8469 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8470 <file>fonts.scale</file> in a font directory:
8473 <file>fonts.dir</file> files must not be provided at all.
8477 <file>fonts.alias</file> and <file>fonts.scale</file>
8478 files, if needed, should be provided in the
8480 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8481 where <var>fontdir</var> is the name of the
8483 <file>/usr/share/fonts/X11/</file> where the
8484 package's corresponding fonts are stored
8485 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8486 <var>package</var> is the name of the package
8487 that provides these fonts, and
8488 <var>extension</var> is either <tt>scale</tt>
8489 or <tt>alias</tt>, whichever corresponds to
8496 Font packages must declare a dependency on
8497 <tt>xfonts-utils</tt> in their control
8502 Font packages that provide one or more
8503 <file>fonts.scale</file> files as described above must
8504 invoke <prgn>update-fonts-scale</prgn> on each
8505 directory into which they installed fonts
8506 <em>before</em> invoking
8507 <prgn>update-fonts-dir</prgn> on that directory.
8508 This invocation must occur in both the
8509 <prgn>postinst</prgn> (for all arguments) and
8510 <prgn>postrm</prgn> (for all arguments except
8511 <tt>upgrade</tt>) scripts.
8515 Font packages that provide one or more
8516 <file>fonts.alias</file> files as described above must
8517 invoke <prgn>update-fonts-alias</prgn> on each
8518 directory into which they installed fonts. This
8519 invocation must occur in both the
8520 <prgn>postinst</prgn> (for all arguments) and
8521 <prgn>postrm</prgn> (for all arguments except
8522 <tt>upgrade</tt>) scripts.
8526 Font packages must invoke
8527 <prgn>update-fonts-dir</prgn> on each directory into
8528 which they installed fonts. This invocation must
8529 occur in both the <prgn>postinst</prgn> (for all
8530 arguments) and <prgn>postrm</prgn> (for all
8531 arguments except <tt>upgrade</tt>) scripts.
8535 Font packages must not provide alias names for the
8536 fonts they include which collide with alias names
8537 already in use by fonts already packaged.
8541 Font packages must not provide fonts with the same
8542 XLFD registry name as another font already packaged.
8549 <heading>Application defaults files</heading>
8552 Application defaults files must be installed in the
8553 directory <file>/etc/X11/app-defaults/</file> (use of a
8554 localized subdirectory of <file>/etc/X11/</file> as described
8555 in the <em>X Toolkit Intrinsics - C Language
8556 Interface</em> manual is also permitted). They must be
8557 registered as <tt>conffile</tt>s or handled as
8558 configuration files.
8562 Customization of programs' X resources may also be
8563 supported with the provision of a file with the same name
8564 as that of the package placed in the
8565 <file>/etc/X11/Xresources/</file> directory, which must
8566 registered as a <tt>conffile</tt> or handled as a
8567 configuration file.<footnote>
8568 Note that this mechanism is not the same as using
8569 app-defaults; app-defaults are tied to the client
8570 binary on the local file system, whereas X resources
8571 are stored in the X server and affect all connecting
8578 <heading>Installation directory issues</heading>
8581 Packages using the X Window System should not be
8582 configured to install files under the
8583 <file>/usr/X11R6/</file> directory. The
8584 <file>/usr/X11R6/</file> directory hierarchy should be
8585 regarded as obsolete.
8589 Programs that use GNU <prgn>autoconf</prgn> and
8590 <prgn>automake</prgn> are usually easily configured at
8591 compile time to use <file>/usr/</file> instead of
8592 <file>/usr/X11R6/</file>, and this should be done whenever
8593 possible. Configuration files for window managers and
8594 display managers should be placed in a subdirectory of
8595 <file>/etc/X11/</file> corresponding to the package name due
8596 to these programs' tight integration with the mechanisms
8597 of the X Window System. Application-level programs should
8598 use the <file>/etc/</file> directory unless otherwise mandated
8603 The installation of files into subdirectories
8604 of <file>/usr/X11R6/include/X11/</file> and
8605 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8606 package maintainers should determine if subdirectories of
8607 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8612 Packages should install any relevant files into the
8613 directories <file>/usr/include/X11/</file> and
8614 <file>/usr/lib/X11/</file>, but if they do so, they must
8615 pre-depend on <tt>x11-common (>=
8616 1:7.0.0)</tt><footnote>
8618 These libraries used to be all symbolic
8619 links. However, with <tt>X11R7</tt>,
8620 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8621 are now real directories, and packages
8622 <strong>should</strong> ship their files here instead
8623 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8624 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8625 responsible for converting these symlinks into
8633 <heading>The OSF/Motif and OpenMotif libraries</heading>
8636 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8637 OpenMotif libraries</em><footnote>
8638 OSF/Motif and OpenMotif are collectively referred to as
8639 "Motif" in this policy document.
8641 should be compiled against and tested with LessTif (a free
8642 re-implementation of Motif) instead. If the maintainer
8643 judges that the program or programs do not work
8644 sufficiently well with LessTif to be distributed and
8645 supported, but do so when compiled against Motif, then two
8646 versions of the package should be created; one linked
8647 statically against Motif and with <tt>-smotif</tt>
8648 appended to the package name, and one linked dynamically
8649 against Motif and with <tt>-dmotif</tt> appended to the
8654 Both Motif-linked versions are dependent
8655 upon non-DFSG-compliant software and thus cannot be
8656 uploaded to the <em>main</em> distribution; if the
8657 software is itself DFSG-compliant it may be uploaded to
8658 the <em>contrib</em> distribution. While known existing
8659 versions of Motif permit unlimited redistribution of
8660 binaries linked against the library (whether statically or
8661 dynamically), it is the package maintainer's
8662 responsibility to determine whether this is permitted by
8663 the license of the copy of Motif in their possession.
8669 <heading>Perl programs and modules</heading>
8672 Perl programs and modules should follow the current Perl policy.
8676 The Perl policy can be found in the <tt>perl-policy</tt>
8677 files in the <tt>debian-policy</tt> package.
8678 It is also available from the Debian web mirrors at
8679 <tt><url name="/doc/packaging-manuals/perl-policy/"
8680 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8685 <heading>Emacs lisp programs</heading>
8688 Please refer to the "Debian Emacs Policy" for details of how to
8689 package emacs lisp programs.
8693 The Emacs policy is available in
8694 <file>debian-emacs-policy.gz</file> of the
8695 <package>emacsen-common</package> package.
8696 It is also available from the Debian web mirrors at
8697 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8698 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8703 <heading>Games</heading>
8706 The permissions on <file>/var/games</file> are mode 755, owner
8707 <tt>root</tt> and group <tt>root</tt>.
8711 Each game decides on its own security policy.</p>
8714 Games which require protected, privileged access to
8715 high-score files, saved games, etc., may be made
8716 set-<em>group</em>-id (mode 2755) and owned by
8717 <tt>root:games</tt>, and use files and directories with
8718 appropriate permissions (770 <tt>root:games</tt>, for
8719 example). They must not be made
8720 set-<em>user</em>-id, as this causes security problems. (If
8721 an attacker can subvert any set-user-id game they can
8722 overwrite the executable of any other, causing other players
8723 of these games to run a Trojan horse program. With a
8724 set-group-id game the attacker only gets access to less
8725 important game data, and if they can get at the other
8726 players' accounts at all it will take considerably more
8730 Some packages, for example some fortune cookie programs, are
8731 configured by the upstream authors to install with their
8732 data files or other static information made unreadable so
8733 that they can only be accessed through set-id programs
8734 provided. You should not do this in a Debian package: anyone can
8735 download the <file>.deb</file> file and read the data from it,
8736 so there is no point making the files unreadable. Not
8737 making the files unreadable also means that you don't have
8738 to make so many programs set-id, which reduces the risk of a
8742 As described in the FHS, binaries of games should be
8743 installed in the directory <file>/usr/games</file>. This also
8744 applies to games that use the X Window System. Manual pages
8745 for games (X and non-X games) should be installed in
8746 <file>/usr/share/man/man6</file>.</p>
8752 <heading>Documentation</heading>
8755 <heading>Manual pages</heading>
8758 You should install manual pages in <prgn>nroff</prgn> source
8759 form, in appropriate places under <file>/usr/share/man</file>.
8760 You should only use sections 1 to 9 (see the FHS for more
8761 details). You must not install a pre-formatted "cat page".
8765 Each program, utility, and function should have an
8766 associated manual page included in the same package. It is
8767 suggested that all configuration files also have a manual
8768 page included as well. Manual pages for protocols and other
8769 auxiliary things are optional.
8773 If no manual page is available, this is considered as a bug
8774 and should be reported to the Debian Bug Tracking System (the
8775 maintainer of the package is allowed to write this bug report
8776 themselves, if they so desire). Do not close the bug report
8777 until a proper man page is available.<footnote>
8778 It is not very hard to write a man page. See the
8779 <url id="http://www.schweikhardt.net/man_page_howto.html"
8780 name="Man-Page-HOWTO">,
8781 <manref name="man" section="7">, the examples
8782 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8783 the helper programs <prgn>help2man</prgn>, or the
8784 directory <file>/usr/share/doc/man-db/examples</file>.
8789 You may forward a complaint about a missing man page to the
8790 upstream authors, and mark the bug as forwarded in the
8791 Debian bug tracking system. Even though the GNU Project do
8792 not in general consider the lack of a man page to be a bug,
8793 we do; if they tell you that they don't consider it a bug
8794 you should leave the bug in our bug tracking system open
8799 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8803 If one man page needs to be accessible via several names it
8804 is better to use a symbolic link than the <file>.so</file>
8805 feature, but there is no need to fiddle with the relevant
8806 parts of the upstream source to change from <file>.so</file> to
8807 symlinks: don't do it unless it's easy. You should not
8808 create hard links in the manual page directories, nor put
8809 absolute filenames in <file>.so</file> directives. The filename
8810 in a <file>.so</file> in a man page should be relative to the
8811 base of the man page tree (usually
8812 <file>/usr/share/man</file>). If you do not create any links
8813 (whether symlinks, hard links, or <tt>.so</tt> directives)
8814 in the file system to the alternate names of the man page,
8815 then you should not rely on <prgn>man</prgn> finding your
8816 man page under those names based solely on the information in
8817 the man page's header.<footnote>
8818 Supporting this in <prgn>man</prgn> often requires
8819 unreasonable processing time to find a manual page or to
8820 report that none exists, and moves knowledge into man's
8821 database that would be better left in the file system.
8822 This support is therefore deprecated and will cease to
8823 be present in the future.
8828 Manual pages in locale-specific subdirectories of
8829 <file>/usr/share/man</file> should use either UTF-8 or the usual
8830 legacy encoding for that language (normally the one corresponding
8831 to the shortest relevant locale name in
8832 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8833 <file>/usr/share/man/fr</file> should use either UTF-8 or
8834 ISO-8859-1.<footnote>
8835 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8836 use. In future, all manual pages will be required to use
8842 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8843 included in the subdirectory name unless it indicates a
8844 significant difference in the language, as this excludes
8845 speakers of the language in other countries.<footnote>
8846 At the time of writing, Chinese and Portuguese are the main
8847 languages with such differences, so <file>pt_BR</file>,
8848 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8853 Due to limitations in current implementations, all characters
8854 in the manual page source should be representable in the usual
8855 legacy encoding for that language, even if the file is
8856 actually encoded in UTF-8. Safe alternative ways to write many
8857 characters outside that range may be found in
8858 <manref name="groff_char" section="7">.
8863 <heading>Info documents</heading>
8866 Info documents should be installed in <file>/usr/share/info</file>.
8867 They should be compressed with <tt>gzip -9</tt>.
8871 Your package should call <prgn>install-info</prgn> to update
8872 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8873 script when called with a <tt>configure</tt> argument, for
8875 <example compact="compact">
8876 install-info --quiet --section Development Development \
8877 /usr/share/info/foobar.info
8881 It is a good idea to specify a section for the location of
8882 your program; this is done with the <tt>--section</tt>
8883 switch. To determine which section to use, you should look
8884 at <file>/usr/share/info/dir</file> on your system and choose the most
8885 relevant (or create a new section if none of the current
8886 sections are relevant). Note that the <tt>--section</tt>
8887 flag takes two arguments; the first is a regular expression
8888 to match (case-insensitively) against an existing section,
8889 the second is used when creating a new one.</p>
8892 You should remove the entries in the <prgn>prerm</prgn>
8893 script when called with a <tt>remove</tt> argument:
8894 <example compact="compact">
8895 install-info --quiet --remove /usr/share/info/foobar.info
8899 If <prgn>install-info</prgn> cannot find a description entry
8900 in the Info file you must supply one. See <manref
8901 name="install-info" section="8"> for details.</p>
8905 <heading>Additional documentation</heading>
8908 Any additional documentation that comes with the package may
8909 be installed at the discretion of the package maintainer.
8910 Plain text documentation should be installed in the directory
8911 <file>/usr/share/doc/<var>package</var></file>, where
8912 <var>package</var> is the name of the package, and
8913 compressed with <tt>gzip -9</tt> unless it is small.
8917 If a package comes with large amounts of documentation which
8918 many users of the package will not require you should create
8919 a separate binary package to contain it, so that it does not
8920 take up disk space on the machines of users who do not need
8921 or want it installed.</p>
8924 It is often a good idea to put text information files
8925 (<file>README</file>s, changelogs, and so forth) that come with
8926 the source package in <file>/usr/share/doc/<var>package</var></file>
8927 in the binary package. However, you don't need to install
8928 the instructions for building and installing the package, of
8932 Packages must not require the existence of any files in
8933 <file>/usr/share/doc/</file> in order to function
8935 The system administrator should be able to
8936 delete files in <file>/usr/share/doc/</file> without causing
8937 any programs to break.
8939 Any files that are referenced by programs but are also
8940 useful as stand alone documentation should be installed under
8941 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8942 <file>/usr/share/doc/<var>package</var></file>.
8946 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8947 link to another directory in <file>/usr/share/doc</file> only if
8948 the two packages both come from the same source and the
8949 first package Depends on the second.<footnote>
8951 Please note that this does not override the section on
8952 changelog files below, so the file
8953 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8954 must refer to the changelog for the current version of
8955 <var>package</var> in question. In practice, this means
8956 that the sources of the target and the destination of the
8957 symlink must be the same (same source package and
8964 Former Debian releases placed all additional documentation
8965 in <file>/usr/doc/<var>package</var></file>. This has been
8966 changed to <file>/usr/share/doc/<var>package</var></file>,
8967 and packages must not put documentation in the directory
8968 <file>/usr/doc/<var>package</var></file>. <footnote>
8969 At this phase of the transition, we no longer require a
8970 symbolic link in <file>/usr/doc/</file>. At a later point,
8971 policy shall change to make the symbolic links a bug.
8977 <heading>Preferred documentation formats</heading>
8980 The unification of Debian documentation is being carried out
8984 If your package comes with extensive documentation in a
8985 markup format that can be converted to various other formats
8986 you should if possible ship HTML versions in a binary
8987 package, in the directory
8988 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8989 its subdirectories.<footnote>
8990 The rationale: The important thing here is that HTML
8991 docs should be available in <em>some</em> package, not
8992 necessarily in the main binary package.
8997 Other formats such as PostScript may be provided at the
8998 package maintainer's discretion.
9002 <sect id="copyrightfile">
9003 <heading>Copyright information</heading>
9006 Every package must be accompanied by a verbatim copy of its
9007 copyright and distribution license in the file
9008 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9009 file must neither be compressed nor be a symbolic link.
9013 In addition, the copyright file must say where the upstream
9014 sources (if any) were obtained. It should name the original
9015 authors of the package and the Debian maintainer(s) who were
9016 involved with its creation.
9020 Packages in the <em>contrib</em> or <em>non-free</em> archive
9021 areas should state in the copyright file that the package is not
9022 part of the Debian GNU/Linux distribution and briefly explain
9027 A copy of the file which will be installed in
9028 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9029 be in <file>debian/copyright</file> in the source package.
9033 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9034 link to another directory in <file>/usr/share/doc</file> only if
9035 the two packages both come from the same source and the
9036 first package Depends on the second. These rules are
9037 important because copyrights must be extractable by
9042 Packages distributed under the UCB BSD license, the Apache
9043 license (version 2.0), the Artistic license, the GNU GPL
9044 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and
9045 the GNU FDL (version 1.2) should refer to the corresponding
9046 files under <file>/usr/share/common-licenses</file>,<footnote>
9049 <file>/usr/share/common-licenses/BSD</file>,
9050 <file>/usr/share/common-licenses/Apache-2.0</file>,
9051 <file>/usr/share/common-licenses/Artistic</file>,
9052 <file>/usr/share/common-licenses/GPL-2</file>,
9053 <file>/usr/share/common-licenses/GPL-3</file>,
9054 <file>/usr/share/common-licenses/LGPL-2</file>,
9055 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9056 <file>/usr/share/common-licenses/LGPL-3</file>, and
9057 <file>/usr/share/common-licenses/GFDL-1.2</file>
9060 </footnote> rather than quoting them in the copyright
9065 You should not use the copyright file as a general <file>README</file>
9066 file. If your package has such a file it should be
9067 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9068 <file>README.Debian</file> or some other appropriate place.</p>
9072 <heading>Examples</heading>
9075 Any examples (configurations, source files, whatever),
9076 should be installed in a directory
9077 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9078 files should not be referenced by any program: they're there
9079 for the benefit of the system administrator and users as
9080 documentation only. Architecture-specific example files
9081 should be installed in a directory
9082 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9084 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9085 latter directory itself may be a symbolic link to the
9090 If the purpose of a package is to provide examples, then the
9091 example files may be installed into
9092 <file>/usr/share/doc/<var>package</var></file>.
9096 <sect id="changelogs">
9097 <heading>Changelog files</heading>
9100 Packages that are not Debian-native must contain a
9101 compressed copy of the <file>debian/changelog</file> file from
9102 the Debian source tree in
9103 <file>/usr/share/doc/<var>package</var></file> with the name
9104 <file>changelog.Debian.gz</file>.
9108 If an upstream changelog is available, it should be accessible as
9109 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9110 plain text. If the upstream changelog is distributed in
9111 HTML, it should be made available in that form as
9112 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9113 and a plain text <file>changelog.gz</file> should be generated
9114 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9115 the upstream changelog files do not already conform to this
9116 naming convention, then this may be achieved either by
9117 renaming the files, or by adding a symbolic link, at the
9118 maintainer's discretion.<footnote>
9119 Rationale: People should not have to look in places for
9120 upstream changelogs merely because they are given
9121 different names or are distributed in HTML format.
9126 All of these files should be installed compressed using
9127 <tt>gzip -9</tt>, as they will become large with time even
9128 if they start out small.
9132 If the package has only one changelog which is used both as
9133 the Debian changelog and the upstream one because there is
9134 no separate upstream maintainer then that changelog should
9135 usually be installed as
9136 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9137 there is a separate upstream maintainer, but no upstream
9138 changelog, then the Debian changelog should still be called
9139 <file>changelog.Debian.gz</file>.
9143 For details about the format and contents of the Debian
9144 changelog file, please see <ref id="dpkgchangelog">.
9149 <appendix id="pkg-scope">
9150 <heading>Introduction and scope of these appendices</heading>
9153 These appendices are taken essentially verbatim from the
9154 now-deprecated Packaging Manual, version 3.2.1.0. They are
9155 the chapters which are likely to be of use to package
9156 maintainers and which have not already been included in the
9157 policy document itself. Most of these sections are very likely
9158 not relevant to policy; they should be treated as
9159 documentation for the packaging system. Please note that these
9160 appendices are included for convenience, and for historical
9161 reasons: they used to be part of policy package, and they have
9162 not yet been incorporated into dpkg documentation. However,
9163 they still have value, and hence they are presented here.
9167 They have not yet been checked to ensure that they are
9168 compatible with the contents of policy, and if there are any
9169 contradictions, the version in the main policy document takes
9170 precedence. The remaining chapters of the old Packaging
9171 Manual have also not been read in detail to ensure that there
9172 are not parts which have been left out. Both of these will be
9177 Certain parts of the Packaging manual were integrated into the
9178 Policy Manual proper, and removed from the appendices. Links
9179 have been placed from the old locations to the new ones.
9183 <prgn>dpkg</prgn> is a suite of programs for creating binary
9184 package files and installing and removing them on Unix
9186 <prgn>dpkg</prgn> is targeted primarily at Debian
9187 GNU/Linux, but may work on or be ported to other
9193 The binary packages are designed for the management of
9194 installed executable programs (usually compiled binaries) and
9195 their associated data, though source code examples and
9196 documentation are provided as part of some packages.</p>
9199 This manual describes the technical aspects of creating Debian
9200 binary packages (<file>.deb</file> files). It documents the
9201 behavior of the package management programs
9202 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9203 they interact with packages.</p>
9206 It also documents the interaction between
9207 <prgn>dselect</prgn>'s core and the access method scripts it
9208 uses to actually install the selected packages, and describes
9209 how to create a new access method.</p>
9212 This manual does not go into detail about the options and
9213 usage of the package building and installation tools. It
9214 should therefore be read in conjunction with those programs'
9219 The utility programs which are provided with <prgn>dpkg</prgn>
9220 for managing various system configuration and similar issues,
9221 such as <prgn>update-rc.d</prgn> and
9222 <prgn>install-info</prgn>, are not described in detail here -
9223 please see their man pages.
9227 It is assumed that the reader is reasonably familiar with the
9228 <prgn>dpkg</prgn> System Administrators' manual.
9229 Unfortunately this manual does not yet exist.
9233 The Debian version of the FSF's GNU hello program is provided
9234 as an example for people wishing to create Debian
9235 packages. The Debian <prgn>debmake</prgn> package is
9236 recommended as a very helpful tool in creating and maintaining
9237 Debian packages. However, while the tools and examples are
9238 helpful, they do not replace the need to read and follow the
9239 Policy and Programmer's Manual.</p>
9242 <appendix id="pkg-binarypkg">
9243 <heading>Binary packages (from old Packaging Manual)</heading>
9246 The binary package has two main sections. The first part
9247 consists of various control information files and scripts used
9248 by <prgn>dpkg</prgn> when installing and removing. See <ref
9249 id="pkg-controlarea">.
9253 The second part is an archive containing the files and
9254 directories to be installed.
9258 In the future binary packages may also contain other
9259 components, such as checksums and digital signatures. The
9260 format for the archive is described in full in the
9261 <file>deb(5)</file> man page.
9265 <sect id="pkg-bincreating"><heading>Creating package files -
9266 <prgn>dpkg-deb</prgn>
9270 All manipulation of binary package files is done by
9271 <prgn>dpkg-deb</prgn>; it's the only program that has
9272 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9273 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9274 will spot that the options requested are appropriate to
9275 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9280 In order to create a binary package you must make a
9281 directory tree which contains all the files and directories
9282 you want to have in the file system data part of the package.
9283 In Debian-format source packages this directory is usually
9284 <file>debian/tmp</file>, relative to the top of the package's
9289 They should have the locations (relative to the root of the
9290 directory tree you're constructing) ownerships and
9291 permissions which you want them to have on the system when
9296 With current versions of <prgn>dpkg</prgn> the uid/username
9297 and gid/groupname mappings for the users and groups being
9298 used should be the same on the system where the package is
9299 built and the one where it is installed.
9303 You need to add one special directory to the root of the
9304 miniature file system tree you're creating:
9305 <prgn>DEBIAN</prgn>. It should contain the control
9306 information files, notably the binary package control file
9307 (see <ref id="pkg-controlfile">).
9311 The <prgn>DEBIAN</prgn> directory will not appear in the
9312 file system archive of the package, and so won't be installed
9313 by <prgn>dpkg</prgn> when the package is installed.
9317 When you've prepared the package, you should invoke:
9319 dpkg --build <var>directory</var>
9324 This will build the package in
9325 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9326 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9327 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9332 See the man page <manref name="dpkg-deb" section="8"> for details of how
9333 to examine the contents of this newly-created file. You may find the
9334 output of following commands enlightening:
9336 dpkg-deb --info <var>filename</var>.deb
9337 dpkg-deb --contents <var>filename</var>.deb
9338 dpkg --contents <var>filename</var>.deb
9340 To view the copyright file for a package you could use this command:
9342 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9347 <sect id="pkg-controlarea">
9348 <heading>Package control information files</heading>
9351 The control information portion of a binary package is a
9352 collection of files with names known to <prgn>dpkg</prgn>.
9353 It will treat the contents of these files specially - some
9354 of them contain information used by <prgn>dpkg</prgn> when
9355 installing or removing the package; others are scripts which
9356 the package maintainer wants <prgn>dpkg</prgn> to run.
9360 It is possible to put other files in the package control
9361 area, but this is not generally a good idea (though they
9362 will largely be ignored).
9366 Here is a brief list of the control info files supported by
9367 <prgn>dpkg</prgn> and a summary of what they're used for.
9372 <tag><tt>control</tt>
9375 This is the key description file used by
9376 <prgn>dpkg</prgn>. It specifies the package's name
9377 and version, gives its description for the user,
9378 states its relationships with other packages, and so
9379 forth. See <ref id="sourcecontrolfiles"> and
9380 <ref id="binarycontrolfiles">.
9384 It is usually generated automatically from information
9385 in the source package by the
9386 <prgn>dpkg-gencontrol</prgn> program, and with
9387 assistance from <prgn>dpkg-shlibdeps</prgn>.
9388 See <ref id="pkg-sourcetools">.
9392 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9397 These are executable files (usually scripts) which
9398 <prgn>dpkg</prgn> runs during installation, upgrade
9399 and removal of packages. They allow the package to
9400 deal with matters which are particular to that package
9401 or require more complicated processing than that
9402 provided by <prgn>dpkg</prgn>. Details of when and
9403 how they are called are in <ref id="maintainerscripts">.
9407 It is very important to make these scripts idempotent.
9408 See <ref id="idempotency">.
9412 The maintainer scripts are guaranteed to run with a
9413 controlling terminal and can interact with the user.
9414 See <ref id="controllingterminal">.
9418 <tag><tt>conffiles</tt>
9421 This file contains a list of configuration files which
9422 are to be handled automatically by <prgn>dpkg</prgn>
9423 (see <ref id="pkg-conffiles">). Note that not necessarily
9424 every configuration file should be listed here.
9427 <tag><tt>shlibs</tt>
9430 This file contains a list of the shared libraries
9431 supplied by the package, with dependency details for
9432 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9433 when it determines what dependencies are required in a
9434 package control file. The <tt>shlibs</tt> file format
9435 is described on <ref id="shlibs">.
9440 <sect id="pkg-controlfile">
9441 <heading>The main control information file: <tt>control</tt></heading>
9444 The most important control information file used by
9445 <prgn>dpkg</prgn> when it installs a package is
9446 <tt>control</tt>. It contains all the package's "vital
9451 The binary package control files of packages built from
9452 Debian sources are made by a special tool,
9453 <prgn>dpkg-gencontrol</prgn>, which reads
9454 <file>debian/control</file> and <file>debian/changelog</file> to
9455 find the information it needs. See <ref id="pkg-sourcepkg"> for
9460 The fields in binary package control files are listed in
9461 <ref id="binarycontrolfiles">.
9465 A description of the syntax of control files and the purpose
9466 of the fields is available in <ref id="controlfields">.
9471 <heading>Time Stamps</heading>
9474 See <ref id="timestamps">.
9479 <appendix id="pkg-sourcepkg">
9480 <heading>Source packages (from old Packaging Manual) </heading>
9483 The Debian binary packages in the distribution are generated
9484 from Debian sources, which are in a special format to assist
9485 the easy and automatic building of binaries.
9488 <sect id="pkg-sourcetools">
9489 <heading>Tools for processing source packages</heading>
9492 Various tools are provided for manipulating source packages;
9493 they pack and unpack sources and help build of binary
9494 packages and help manage the distribution of new versions.
9498 They are introduced and typical uses described here; see
9499 <manref name="dpkg-source" section="1"> for full
9500 documentation about their arguments and operation.
9504 For examples of how to construct a Debian source package,
9505 and how to use those utilities that are used by Debian
9506 source packages, please see the <prgn>hello</prgn> example
9510 <sect1 id="pkg-dpkg-source">
9512 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9517 This program is frequently used by hand, and is also
9518 called from package-independent automated building scripts
9519 such as <prgn>dpkg-buildpackage</prgn>.
9523 To unpack a package it is typically invoked with
9525 dpkg-source -x <var>.../path/to/filename</var>.dsc
9530 with the <file><var>filename</var>.tar.gz</file> and
9531 <file><var>filename</var>.diff.gz</file> (if applicable) in
9532 the same directory. It unpacks into
9533 <file><var>package</var>-<var>version</var></file>, and if
9535 <file><var>package</var>-<var>version</var>.orig</file>, in
9536 the current directory.
9540 To create a packed source archive it is typically invoked:
9542 dpkg-source -b <var>package</var>-<var>version</var>
9547 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9548 <file>.diff.gz</file> (if appropriate) in the current
9549 directory. <prgn>dpkg-source</prgn> does not clean the
9550 source tree first - this must be done separately if it is
9555 See also <ref id="pkg-sourcearchives">.</p>
9559 <sect1 id="pkg-dpkg-buildpackage">
9561 <prgn>dpkg-buildpackage</prgn> - overall package-building
9566 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9567 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9568 targets <tt>clean</tt>, <tt>build</tt> and
9569 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9570 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9571 source and binary package upload.
9575 It is usually invoked by hand from the top level of the
9576 built or unbuilt source directory. It may be invoked with
9577 no arguments; useful arguments include:
9578 <taglist compact="compact">
9579 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9582 Do not sign the <tt>.changes</tt> file or the
9583 source package <tt>.dsc</tt> file, respectively.</p>
9585 <tag><tt>-p<var>sign-command</var></tt></tag>
9588 Invoke <var>sign-command</var> instead of finding
9589 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9590 <var>sign-command</var> must behave just like
9591 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9593 <tag><tt>-r<var>root-command</var></tt></tag>
9596 When root privilege is required, invoke the command
9597 <var>root-command</var>. <var>root-command</var>
9598 should invoke its first argument as a command, from
9599 the <prgn>PATH</prgn> if necessary, and pass its
9600 second and subsequent arguments to the command it
9601 calls. If no <var>root-command</var> is supplied
9602 then <var>dpkg-buildpackage</var> will take no
9603 special action to gain root privilege, so that for
9604 most packages it will have to be invoked as root to
9607 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9610 Two types of binary-only build and upload - see
9611 <manref name="dpkg-source" section="1">.
9618 <sect1 id="pkg-dpkg-gencontrol">
9620 <prgn>dpkg-gencontrol</prgn> - generates binary package
9625 This program is usually called from <file>debian/rules</file>
9626 (see <ref id="pkg-sourcetree">) in the top level of the source
9631 This is usually done just before the files and directories in the
9632 temporary directory tree where the package is being built have their
9633 permissions and ownerships set and the package is constructed using
9634 <prgn>dpkg-deb/</prgn>
9636 This is so that the control file which is produced has
9637 the right permissions
9642 <prgn>dpkg-gencontrol</prgn> must be called after all the
9643 files which are to go into the package have been placed in
9644 the temporary build directory, so that its calculation of
9645 the installed size of a package is correct.
9649 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9650 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9651 variable substitutions created by
9652 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9657 For a package which generates only one binary package, and
9658 which builds it in <file>debian/tmp</file> relative to the top
9659 of the source package, it is usually sufficient to call
9660 <prgn>dpkg-gencontrol</prgn>.
9664 Sources which build several binaries will typically need
9667 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9668 </example> The <tt>-P</tt> tells
9669 <prgn>dpkg-gencontrol</prgn> that the package is being
9670 built in a non-default directory, and the <tt>-p</tt>
9671 tells it which package's control file should be generated.
9675 <prgn>dpkg-gencontrol</prgn> also adds information to the
9676 list of files in <file>debian/files</file>, for the benefit of
9677 (for example) a future invocation of
9678 <prgn>dpkg-genchanges</prgn>.</p>
9681 <sect1 id="pkg-dpkg-shlibdeps">
9683 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9688 This program is usually called from <file>debian/rules</file>
9689 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9690 id="pkg-sourcetree">), in the top level of the source tree.
9694 Its arguments are executables and shared libraries
9697 They may be specified either in the locations in the
9698 source tree where they are created or in the locations
9699 in the temporary build tree where they are installed
9700 prior to binary package creation.
9702 </footnote> for which shared library dependencies should
9703 be included in the binary package's control file.
9707 If some of the found shared libraries should only
9708 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9709 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9710 by using the <tt>-d<var>dependency-field</var></tt> option
9711 before those executable(s). (Each <tt>-d</tt> option
9712 takes effect until the next <tt>-d</tt>.)
9716 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9717 output control file to be modified. Instead by default it
9718 adds to the <file>debian/substvars</file> file variable
9719 settings like <tt>shlibs:Depends</tt>. These variable
9720 settings must be referenced in dependency fields in the
9721 appropriate per-binary-package sections of the source
9726 For example, a package that generates an essential part
9727 which requires dependencies, and optional parts that
9728 which only require a recommendation, would separate those
9729 two sets of dependencies into two different fields.<footnote>
9730 At the time of writing, an example for this was the
9731 <package/xmms/ package, with Depends used for the xmms
9732 executable, Recommends for the plug-ins and Suggests for
9733 even more optional features provided by unzip.
9735 It can say in its <file>debian/rules</file>:
9737 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9738 -dRecommends <var>optionalpart anotheroptionalpart</var>
9740 and then in its main control file <file>debian/control</file>:
9743 Depends: ${shlibs:Depends}
9744 Recommends: ${shlibs:Recommends}
9750 Sources which produce several binary packages with
9751 different shared library dependency requirements can use
9752 the <tt>-p<var>varnameprefix</var></tt> option to override
9753 the default <tt>shlibs:</tt> prefix (one invocation of
9754 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9755 They can thus produce several sets of dependency
9756 variables, each of the form
9757 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9758 which can be referred to in the appropriate parts of the
9759 binary package control files.
9764 <sect1 id="pkg-dpkg-distaddfile">
9766 <prgn>dpkg-distaddfile</prgn> - adds a file to
9767 <file>debian/files</file>
9771 Some packages' uploads need to include files other than
9772 the source and binary package files.
9776 <prgn>dpkg-distaddfile</prgn> adds a file to the
9777 <file>debian/files</file> file so that it will be included in
9778 the <file>.changes</file> file when
9779 <prgn>dpkg-genchanges</prgn> is run.
9783 It is usually invoked from the <tt>binary</tt> target of
9784 <file>debian/rules</file>:
9786 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9788 The <var>filename</var> is relative to the directory where
9789 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9790 is usually the directory above the top level of the source
9791 tree. The <file>debian/rules</file> target should put the
9792 file there just before or just after calling
9793 <prgn>dpkg-distaddfile</prgn>.
9797 The <var>section</var> and <var>priority</var> are passed
9798 unchanged into the resulting <file>.changes</file> file.
9803 <sect1 id="pkg-dpkg-genchanges">
9805 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9810 This program is usually called by package-independent
9811 automatic building scripts such as
9812 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9817 It is usually called in the top level of a built source
9818 tree, and when invoked with no arguments will print out a
9819 straightforward <file>.changes</file> file based on the
9820 information in the source package's changelog and control
9821 file and the binary and source packages which should have
9827 <sect1 id="pkg-dpkg-parsechangelog">
9829 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9830 representation of a changelog
9834 This program is used internally by
9835 <prgn>dpkg-source</prgn> et al. It may also occasionally
9836 be useful in <file>debian/rules</file> and elsewhere. It
9837 parses a changelog, <file>debian/changelog</file> by default,
9838 and prints a control-file format representation of the
9839 information in it to standard output.
9843 <sect1 id="pkg-dpkg-architecture">
9845 <prgn>dpkg-architecture</prgn> - information about the build and
9850 This program can be used manually, but is also invoked by
9851 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9852 environment or make variables which specify the build and host
9853 architecture for the package building process.
9858 <sect id="pkg-sourcetree">
9859 <heading>The Debianised source tree</heading>
9862 The source archive scheme described later is intended to
9863 allow a Debianised source tree with some associated control
9864 information to be reproduced and transported easily. The
9865 Debianised source tree is a version of the original program
9866 with certain files added for the benefit of the
9867 Debianisation process, and with any other changes required
9868 made to the rest of the source code and installation
9873 The extra files created for Debian are in the subdirectory
9874 <file>debian</file> of the top level of the Debianised source
9875 tree. They are described below.
9878 <sect1 id="pkg-debianrules">
9879 <heading><file>debian/rules</file> - the main building script</heading>
9882 See <ref id="debianrules">.
9887 <sect1 id="pkg-dpkgchangelog">
9888 <heading><file>debian/changelog</file></heading>
9891 See <ref id="dpkgchangelog">.
9894 <sect2><heading>Defining alternative changelog formats
9898 It is possible to use a different format to the standard
9899 one, by providing a parser for the format you wish to
9904 In order to have <tt>dpkg-parsechangelog</tt> run your
9905 parser, you must include a line within the last 40 lines
9906 of your file matching the Perl regular expression:
9907 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9908 parentheses should be the name of the format. For
9909 example, you might say:
9911 @@@ changelog-format: joebloggs @@@
9913 Changelog format names are non-empty strings of alphanumerics.
9917 If such a line exists then <tt>dpkg-parsechangelog</tt>
9918 will look for the parser as
9919 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9921 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9922 it is an error for it not to find it, or for it not to
9923 be an executable program. The default changelog format
9924 is <tt>dpkg</tt>, and a parser for it is provided with
9925 the <tt>dpkg</tt> package.
9929 The parser will be invoked with the changelog open on
9930 standard input at the start of the file. It should read
9931 the file (it may seek if it wishes) to determine the
9932 information required and return the parsed information
9933 to standard output in the form of a series of control
9934 fields in the standard format. By default it should
9935 return information about only the most recent version in
9936 the changelog; it should accept a
9937 <tt>-v<var>version</var></tt> option to return changes
9938 information from all versions present <em>strictly
9939 after</em> <var>version</var>, and it should then be an
9940 error for <var>version</var> not to be present in the
9946 <list compact="compact">
9947 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9948 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9949 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9950 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9951 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9952 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9953 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9958 If several versions are being returned (due to the use
9959 of <tt>-v</tt>), the urgency value should be of the
9960 highest urgency code listed at the start of any of the
9961 versions requested followed by the concatenated
9962 (space-separated) comments from all the versions
9963 requested; the maintainer, version, distribution and
9964 date should always be from the most recent version.
9968 For the format of the <tt>Changes</tt> field see
9969 <ref id="f-Changes">.
9973 If the changelog format which is being parsed always or
9974 almost always leaves a blank line between individual
9975 change notes these blank lines should be stripped out,
9976 so as to make the resulting output compact.
9980 If the changelog format does not contain date or package
9981 name information this information should be omitted from
9982 the output. The parser should not attempt to synthesize
9983 it or find it from other sources.
9987 If the changelog does not have the expected format the
9988 parser should exit with a nonzero exit status, rather
9989 than trying to muddle through and possibly generating
9994 A changelog parser may not interact with the user at
10000 <sect1 id="pkg-srcsubstvars">
10001 <heading><file>debian/substvars</file> and variable substitutions</heading>
10004 See <ref id="substvars">.
10010 <heading><file>debian/files</file></heading>
10013 See <ref id="debianfiles">.
10017 <sect1><heading><file>debian/tmp</file>
10021 This is the canonical temporary location for the
10022 construction of binary packages by the <tt>binary</tt>
10023 target. The directory <file>tmp</file> serves as the root of
10024 the file system tree as it is being constructed (for
10025 example, by using the package's upstream makefiles install
10026 targets and redirecting the output there), and it also
10027 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10028 id="pkg-bincreating">.
10032 If several binary packages are generated from the same
10033 source tree it is usual to use several
10034 <file>debian/tmp<var>something</var></file> directories, for
10035 example <file>tmp-a</file> or <file>tmp-doc</file>.
10039 Whatever <file>tmp</file> directories are created and used by
10040 <tt>binary</tt> must of course be removed by the
10041 <tt>clean</tt> target.</p></sect1>
10045 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10049 As it exists on the FTP site, a Debian source package
10050 consists of three related files. You must have the right
10051 versions of all three to be able to use them.
10056 <tag>Debian source control file - <tt>.dsc</tt></tag>
10058 This file is a control file used by <prgn>dpkg-source</prgn>
10059 to extract a source package.
10060 See <ref id="debiansourcecontrolfiles">.
10064 Original source archive -
10066 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10072 This is a compressed (with <tt>gzip -9</tt>)
10073 <prgn>tar</prgn> file containing the source code from
10074 the upstream authors of the program.
10079 Debianisation diff -
10081 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10087 This is a unified context diff (<tt>diff -u</tt>)
10088 giving the changes which are required to turn the
10089 original source into the Debian source. These changes
10090 may only include editing and creating plain files.
10091 The permissions of files, the targets of symbolic
10092 links and the characteristics of special files or
10093 pipes may not be changed and no files may be removed
10098 All the directories in the diff must exist, except the
10099 <file>debian</file> subdirectory of the top of the source
10100 tree, which will be created by
10101 <prgn>dpkg-source</prgn> if necessary when unpacking.
10105 The <prgn>dpkg-source</prgn> program will
10106 automatically make the <file>debian/rules</file> file
10107 executable (see below).</p></item>
10112 If there is no original source code - for example, if the
10113 package is specially prepared for Debian or the Debian
10114 maintainer is the same as the upstream maintainer - the
10115 format is slightly different: then there is no diff, and the
10117 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10118 and preferably contains a directory named
10119 <file><var>package</var>-<var>version</var></file>.
10124 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10127 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10128 Debian source package. However, if it is not available it
10129 is possible to unpack a Debian source archive as follows:
10130 <enumlist compact="compact">
10133 Untar the tarfile, which will create a <file>.orig</file>
10137 <p>Rename the <file>.orig</file> directory to
10138 <file><var>package</var>-<var>version</var></file>.</p>
10142 Create the subdirectory <file>debian</file> at the top of
10143 the source tree.</p>
10145 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10147 <item><p>Untar the tarfile again if you want a copy of the original
10148 source code alongside the Debianised version.</p>
10153 It is not possible to generate a valid Debian source archive
10154 without using <prgn>dpkg-source</prgn>. In particular,
10155 attempting to use <prgn>diff</prgn> directly to generate the
10156 <file>.diff.gz</file> file will not work.
10160 <heading>Restrictions on objects in source packages</heading>
10163 The source package may not contain any hard links
10165 This is not currently detected when building source
10166 packages, but only when extracting
10170 Hard links may be permitted at some point in the
10171 future, but would require a fair amount of
10173 </footnote>, device special files, sockets or setuid or
10176 Setgid directories are allowed.
10181 The source packaging tools manage the changes between the
10182 original and Debianised source using <prgn>diff</prgn> and
10183 <prgn>patch</prgn>. Turning the original source tree as
10184 included in the <file>.orig.tar.gz</file> into the debianised
10185 source must not involve any changes which cannot be
10186 handled by these tools. Problematic changes which cause
10187 <prgn>dpkg-source</prgn> to halt with an error when
10188 building the source package are:
10189 <list compact="compact">
10190 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10192 <item><p>Changing the targets of symbolic links.</p>
10194 <item><p>Creating directories, other than <file>debian</file>.</p>
10196 <item><p>Changes to the contents of binary files.</p></item>
10197 </list> Changes which cause <prgn>dpkg-source</prgn> to
10198 print a warning but continue anyway are:
10199 <list compact="compact">
10202 Removing files, directories or symlinks.
10204 Renaming a file is not treated specially - it is
10205 seen as the removal of the old file (which
10206 generates a warning, but is otherwise ignored),
10207 and the creation of the new one.
10213 Changed text files which are missing the usual final
10214 newline (either in the original or the modified
10219 Changes which are not represented, but which are not detected by
10220 <prgn>dpkg-source</prgn>, are:
10221 <list compact="compact">
10222 <item><p>Changing the permissions of files (other than
10223 <file>debian/rules</file>) and directories.</p></item>
10228 The <file>debian</file> directory and <file>debian/rules</file>
10229 are handled specially by <prgn>dpkg-source</prgn> - before
10230 applying the changes it will create the <file>debian</file>
10231 directory, and afterwards it will make
10232 <file>debian/rules</file> world-executable.
10238 <appendix id="pkg-controlfields">
10239 <heading>Control files and their fields (from old Packaging Manual)</heading>
10242 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10243 data in a common format, known as control files. Binary and
10244 source packages have control data as do the <file>.changes</file>
10245 files which control the installation of uploaded files, and
10246 <prgn>dpkg</prgn>'s internal databases are in a similar
10251 <heading>Syntax of control files</heading>
10254 See <ref id="controlsyntax">.
10258 It is important to note that there are several fields which
10259 are optional as far as <prgn>dpkg</prgn> and the related
10260 tools are concerned, but which must appear in every Debian
10261 package, or whose omission may cause problems.
10266 <heading>List of fields</heading>
10269 See <ref id="controlfieldslist">.
10273 This section now contains only the fields that didn't belong
10274 to the Policy manual.
10277 <sect1 id="pkg-f-Filename">
10278 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10281 These fields in <tt>Packages</tt> files give the
10282 filename(s) of (the parts of) a package in the
10283 distribution directories, relative to the root of the
10284 Debian hierarchy. If the package has been split into
10285 several parts the parts are all listed in order, separated
10290 <sect1 id="pkg-f-Size">
10291 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10294 These fields in <file>Packages</file> files give the size (in
10295 bytes, expressed in decimal) and MD5 checksum of the
10296 file(s) which make(s) up a binary package in the
10297 distribution. If the package is split into several parts
10298 the values for the parts are listed in order, separated by
10303 <sect1 id="pkg-f-Status">
10304 <heading><tt>Status</tt></heading>
10307 This field in <prgn>dpkg</prgn>'s status file records
10308 whether the user wants a package installed, removed or
10309 left alone, whether it is broken (requiring
10310 re-installation) or not and what its current state on the
10311 system is. Each of these pieces of information is a
10316 <sect1 id="pkg-f-Config-Version">
10317 <heading><tt>Config-Version</tt></heading>
10320 If a package is not installed or not configured, this
10321 field in <prgn>dpkg</prgn>'s status file records the last
10322 version of the package which was successfully
10327 <sect1 id="pkg-f-Conffiles">
10328 <heading><tt>Conffiles</tt></heading>
10331 This field in <prgn>dpkg</prgn>'s status file contains
10332 information about the automatically-managed configuration
10333 files held by a package. This field should <em>not</em>
10334 appear anywhere in a package!
10339 <heading>Obsolete fields</heading>
10342 These are still recognized by <prgn>dpkg</prgn> but should
10343 not appear anywhere any more.
10345 <taglist compact="compact">
10347 <tag><tt>Revision</tt></tag>
10348 <tag><tt>Package-Revision</tt></tag>
10349 <tag><tt>Package_Revision</tt></tag>
10351 The Debian revision part of the package version was
10352 at one point in a separate control file field. This
10353 field went through several names.
10356 <tag><tt>Recommended</tt></tag>
10357 <item>Old name for <tt>Recommends</tt>.</item>
10359 <tag><tt>Optional</tt></tag>
10360 <item>Old name for <tt>Suggests</tt>.</item>
10362 <tag><tt>Class</tt></tag>
10363 <item>Old name for <tt>Priority</tt>.</item>
10372 <appendix id="pkg-conffiles">
10373 <heading>Configuration file handling (from old Packaging Manual)</heading>
10376 <prgn>dpkg</prgn> can do a certain amount of automatic
10377 handling of package configuration files.
10381 Whether this mechanism is appropriate depends on a number of
10382 factors, but basically there are two approaches to any
10383 particular configuration file.
10387 The easy method is to ship a best-effort configuration in the
10388 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10389 handle updates. If the user is unlikely to want to edit the
10390 file, but you need them to be able to without losing their
10391 changes, and a new package with a changed version of the file
10392 is only released infrequently, this is a good approach.
10396 The hard method is to build the configuration file from
10397 scratch in the <prgn>postinst</prgn> script, and to take the
10398 responsibility for fixing any mistakes made in earlier
10399 versions of the package automatically. This will be
10400 appropriate if the file is likely to need to be different on
10404 <sect><heading>Automatic handling of configuration files by
10409 A package may contain a control area file called
10410 <tt>conffiles</tt>. This file should be a list of filenames
10411 of configuration files needing automatic handling, separated
10412 by newlines. The filenames should be absolute pathnames,
10413 and the files referred to should actually exist in the
10418 When a package is upgraded <prgn>dpkg</prgn> will process
10419 the configuration files during the configuration stage,
10420 shortly before it runs the package's <prgn>postinst</prgn>
10425 For each file it checks to see whether the version of the
10426 file included in the package is the same as the one that was
10427 included in the last version of the package (the one that is
10428 being upgraded from); it also compares the version currently
10429 installed on the system with the one shipped with the last
10434 If neither the user nor the package maintainer has changed
10435 the file, it is left alone. If one or the other has changed
10436 their version, then the changed version is preferred - i.e.,
10437 if the user edits their file, but the package maintainer
10438 doesn't ship a different version, the user's changes will
10439 stay, silently, but if the maintainer ships a new version
10440 and the user hasn't edited it the new version will be
10441 installed (with an informative message). If both have
10442 changed their version the user is prompted about the problem
10443 and must resolve the differences themselves.
10447 The comparisons are done by calculating the MD5 message
10448 digests of the files, and storing the MD5 of the file as it
10449 was included in the most recent version of the package.
10453 When a package is installed for the first time
10454 <prgn>dpkg</prgn> will install the file that comes with it,
10455 unless that would mean overwriting a file already on the
10460 However, note that <prgn>dpkg</prgn> will <em>not</em>
10461 replace a conffile that was removed by the user (or by a
10462 script). This is necessary because with some programs a
10463 missing file produces an effect hard or impossible to
10464 achieve in another way, so that a missing file needs to be
10465 kept that way if the user did it.
10469 Note that a package should <em>not</em> modify a
10470 <prgn>dpkg</prgn>-handled conffile in its maintainer
10471 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10472 the user confusing and possibly dangerous options for
10473 conffile update when the package is upgraded.</p>
10476 <sect><heading>Fully-featured maintainer script configuration
10481 For files which contain site-specific information such as
10482 the hostname and networking details and so forth, it is
10483 better to create the file in the package's
10484 <prgn>postinst</prgn> script.
10488 This will typically involve examining the state of the rest
10489 of the system to determine values and other information, and
10490 may involve prompting the user for some information which
10491 can't be obtained some other way.
10495 When using this method there are a couple of important
10496 issues which should be considered:
10500 If you discover a bug in the program which generates the
10501 configuration file, or if the format of the file changes
10502 from one version to the next, you will have to arrange for
10503 the postinst script to do something sensible - usually this
10504 will mean editing the installed configuration file to remove
10505 the problem or change the syntax. You will have to do this
10506 very carefully, since the user may have changed the file,
10507 perhaps to fix the very problem that your script is trying
10508 to deal with - you will have to detect these situations and
10509 deal with them correctly.
10513 If you do go down this route it's probably a good idea to
10514 make the program that generates the configuration file(s) a
10515 separate program in <file>/usr/sbin</file>, by convention called
10516 <file><var>package</var>config</file> and then run that if
10517 appropriate from the post-installation script. The
10518 <tt><var>package</var>config</tt> program should not
10519 unquestioningly overwrite an existing configuration - if its
10520 mode of operation is geared towards setting up a package for
10521 the first time (rather than any arbitrary reconfiguration
10522 later) you should have it check whether the configuration
10523 already exists, and require a <tt>--force</tt> flag to
10524 overwrite it.</p></sect>
10527 <appendix id="pkg-alternatives"><heading>Alternative versions of
10528 an interface - <prgn>update-alternatives</prgn> (from old
10533 When several packages all provide different versions of the
10534 same program or file it is useful to have the system select a
10535 default, but to allow the system administrator to change it
10536 and have their decisions respected.
10540 For example, there are several versions of the <prgn>vi</prgn>
10541 editor, and there is no reason to prevent all of them from
10542 being installed at once, each under their own name
10543 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10544 Nevertheless it is desirable to have the name <tt>vi</tt>
10545 refer to something, at least by default.
10549 If all the packages involved cooperate, this can be done with
10550 <prgn>update-alternatives</prgn>.
10554 Each package provides its own version under its own name, and
10555 calls <prgn>update-alternatives</prgn> in its postinst to
10556 register its version (and again in its prerm to deregister
10561 See the man page <manref name="update-alternatives"
10562 section="8"> for details.
10566 If <prgn>update-alternatives</prgn> does not seem appropriate
10567 you may wish to consider using diversions instead.</p>
10570 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10571 package's version of a file (from old Packaging Manual)
10575 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10576 when it reinstalls the package it belongs to, and to have it
10577 put the file from the package somewhere else instead.
10581 This can be used locally to override a package's version of a
10582 file, or by one package to override another's version (or
10583 provide a wrapper for it).
10587 Before deciding to use a diversion, read <ref
10588 id="pkg-alternatives"> to see if you really want a diversion
10589 rather than several alternative versions of a program.
10593 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10594 and updated by a special program <prgn>dpkg-divert</prgn>.
10595 Please see <manref name="dpkg-divert" section="8"> for full
10596 details of its operation.
10600 When a package wishes to divert a file from another, it should
10601 call <prgn>dpkg-divert</prgn> in its preinst to add the
10602 diversion and rename the existing file. For example,
10603 supposing that a <prgn>smailwrapper</prgn> package wishes to
10604 install a wrapper around <file>/usr/sbin/smail</file>:
10606 dpkg-divert --package smailwrapper --add --rename \
10607 --divert /usr/sbin/smail.real /usr/sbin/smail
10608 </example> The <tt>--package smailwrapper</tt> ensures that
10609 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10610 can bypass the diversion and get installed as the true version.
10611 It's safe to add the diversion unconditionally on upgrades since
10612 it will be left unchanged if it already exists, but
10613 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10614 message, make the command conditional on the version from which
10615 the package is being upgraded:
10617 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10618 dpkg-divert --package smailwrapper --add --rename \
10619 --divert /usr/sbin/smail.real /usr/sbin/smail
10621 </example> where <tt>1.0-2</tt> is the version at which the
10622 diversion was first added to the package. Running the command
10623 during abort-upgrade is pointless but harmless.
10627 The postrm has to do the reverse:
10629 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10630 dpkg-divert --package smailwrapper --remove --rename \
10631 --divert /usr/sbin/smail.real /usr/sbin/smail
10633 </example> If the diversion was added at a particular version, the
10634 postrm should also handle the failure case of upgrading from an
10635 older version (unless the older version is so old that direct
10636 upgrades are no longer supported):
10638 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10639 dpkg-divert --package smailwrapper --remove --rename \
10640 --divert /usr/sbin/smail.real /usr/sbin/smail
10642 </example> where <tt>1.02-2</tt> is the version at which the
10643 diversion was first added to the package. The postrm should not
10644 remove the diversion on upgrades both because there's no reason to
10645 remove the diversion only to immediately re-add it and since the
10646 postrm of the old package is run after unpacking so the removal of
10647 the diversion will fail.
10651 Do not attempt to divert a file which is vitally important for
10652 the system's operation - when using <prgn>dpkg-divert</prgn>
10653 there is a time, after it has been diverted but before
10654 <prgn>dpkg</prgn> has installed the new version, when the file
10655 does not exist.</p>
10660 <!-- Local variables: -->
10661 <!-- indent-tabs-mode: t -->
10663 <!-- vim:set ai et sts=2 sw=2 tw=76: -->