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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy"
161 id="http://packages.debian.org/debian-policy"></package>
162 (<httpsite>packages.debian.org</httpsite>
163 <httppath>/debian-policy</httppath>).
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name="/doc/debian-policy/"
170 id="http://www.debian.org/doc/debian-policy/"></tt>.
172 <httpsite>www.debian.org</httpsite>
173 <httppath>/doc/debian-policy/</httppath>)
174 Also available from the same directory are several other
175 formats: <file>policy.html.tar.gz</file>
176 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
177 <file>policy.pdf.gz</file>
178 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
179 and <file>policy.ps.gz</file>
180 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
184 The <package>debian-policy</package> package also includes the file
185 <file>upgrading-checklist.txt.gz</file> which indicates policy
186 changes between versions of this document.
191 <heading>Authors and Maintainers</heading>
194 Originally called "Debian GNU/Linux Policy Manual", this
195 manual was initially written in 1996 by Ian Jackson.
196 It was revised on November 27th, 1996 by David A. Morris.
197 Christian Schwarz added new sections on March 15th, 1997,
198 and reworked/restructured it in April-July 1997.
199 Christoph Lameter contributed the "Web Standard".
200 Julian Gilbey largely restructured it in 2001.
204 Since September 1998, the responsibility for the contents of
205 this document lies on the <url name="debian-policy mailing list"
206 id="mailto:debian-policy@lists.debian.org">. Proposals
207 are discussed there and inserted into policy after a certain
208 consensus is established.
209 <!-- insert shameless policy-process plug here eventually -->
210 The actual editing is done by a group of maintainers that have
211 no editorial powers. These are the current maintainers:
214 <item>Julian Gilbey</item>
215 <item>Branden Robinson</item>
216 <item>Josip Rodin</item>
217 <item>Manoj Srivastava</item>
222 While the authors of this document have tried hard to avoid
223 typos and other errors, these do still occur. If you discover
224 an error in this manual or if you want to give any
225 comments, suggestions, or criticisms please send an email to
226 the Debian Policy List,
227 <email>debian-policy@lists.debian.org</email>, or submit a
228 bug report against the <tt>debian-policy</tt> package.
232 Please do not try to reach the individual authors or maintainers
233 of the Policy Manual regarding changes to the Policy.
238 <heading>Related documents</heading>
241 There are several other documents other than this Policy Manual
242 that are necessary to fully understand some Debian policies and
247 The external "sub-policy" documents are referred to in:
248 <list compact="compact">
249 <item><ref id="fhs"></item>
250 <item><ref id="virtual_pkg"></item>
251 <item><ref id="menus"></item>
252 <item><ref id="mime"></item>
253 <item><ref id="perl"></item>
254 <item><ref id="maintscriptprompt"></item>
255 <item><ref id="emacs"></item>
260 In addition to those, which carry the weight of policy, there
261 is the Debian Developer's Reference. This document describes
262 procedures and resources for Debian developers, but it is
263 <em>not</em> normative; rather, it includes things that don't
264 belong in the Policy, such as best practices for developers.
268 The Developer's Reference is available in the
269 <package>developers-reference</package> package.
270 It's also available from the Debian web mirrors at
271 <tt><url name="/doc/developers-reference/"
272 id="http://www.debian.org/doc/developers-reference/"></tt>.
276 <sect id="definitions">
277 <heading>Definitions</heading>
280 The following terms are used in this Policy Manual:
284 The character encoding specified by ANSI X3.4-1986 and its
285 predecessor standards, referred to in MIME as US-ASCII, and
286 corresponding to an encoding in eight bits per character of
287 the first 128 <url id="http://www.unicode.org/"
288 name="Unicode"> characters, with the eighth bit always zero.
292 The transformation format (sometimes called encoding) of
293 <url id="http://www.unicode.org/" name="Unicode"> defined by
294 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
295 name="RFC 3629">. UTF-8 has the useful property of having
296 ASCII as a subset, so any text encoded in ASCII is trivially
306 <heading>The Debian Archive</heading>
309 The Debian GNU/Linux system is maintained and distributed as a
310 collection of <em>packages</em>. Since there are so many of
311 them (currently well over 15000), they are split into
312 <em>sections</em> and given <em>priorities</em> to simplify
313 the handling of them.
317 The effort of the Debian project is to build a free operating
318 system, but not every package we want to make accessible is
319 <em>free</em> in our sense (see the Debian Free Software
320 Guidelines, below), or may be imported/exported without
321 restrictions. Thus, the archive is split into areas<footnote>
322 The Debian archive software uses the term "component" internally
323 and in the Release file format to refer to the division of an
324 archive. The Debian Social Contract simply refers to "areas."
325 This document uses terminology similar to the Social Contract.
326 </footnote> based on their licenses and other restrictions.
330 The aims of this are:
332 <list compact="compact">
333 <item>to allow us to make as much software available as we can</item>
334 <item>to allow us to encourage everyone to write free software,
336 <item>to allow us to make it easy for people to produce
337 CD-ROMs of our system without violating any licenses,
338 import/export restrictions, or any other laws.</item>
343 The <em>main</em> archive area forms the <em>Debian GNU/Linux
348 Packages in the other archive areas (<tt>contrib</tt>,
349 <tt>non-free</tt>) are not considered to be part of the Debian
350 distribution, although we support their use and provide
351 infrastructure for them (such as our bug-tracking system and
352 mailing lists). This Debian Policy Manual applies to these
357 <heading>The Debian Free Software Guidelines</heading>
359 The Debian Free Software Guidelines (DFSG) form our
360 definition of "free software". These are:
362 <tag>Free Redistribution
365 The license of a Debian component may not restrict any
366 party from selling or giving away the software as a
367 component of an aggregate software distribution
368 containing programs from several different
369 sources. The license may not require a royalty or
370 other fee for such sale.
375 The program must include source code, and must allow
376 distribution in source code as well as compiled form.
381 The license must allow modifications and derived
382 works, and must allow them to be distributed under the
383 same terms as the license of the original software.
385 <tag>Integrity of The Author's Source Code
388 The license may restrict source-code from being
389 distributed in modified form <em>only</em> if the
390 license allows the distribution of "patch files"
391 with the source code for the purpose of modifying the
392 program at build time. The license must explicitly
393 permit distribution of software built from modified
394 source code. The license may require derived works to
395 carry a different name or version number from the
396 original software. (This is a compromise. The Debian
397 Project encourages all authors to not restrict any
398 files, source or binary, from being modified.)
400 <tag>No Discrimination Against Persons or Groups
403 The license must not discriminate against any person
406 <tag>No Discrimination Against Fields of Endeavor
409 The license must not restrict anyone from making use
410 of the program in a specific field of endeavor. For
411 example, it may not restrict the program from being
412 used in a business, or from being used for genetic
415 <tag>Distribution of License
418 The rights attached to the program must apply to all
419 to whom the program is redistributed without the need
420 for execution of an additional license by those
423 <tag>License Must Not Be Specific to Debian
426 The rights attached to the program must not depend on
427 the program's being part of a Debian system. If the
428 program is extracted from Debian and used or
429 distributed without Debian but otherwise within the
430 terms of the program's license, all parties to whom
431 the program is redistributed must have the same
432 rights as those that are granted in conjunction with
435 <tag>License Must Not Contaminate Other Software
438 The license must not place restrictions on other
439 software that is distributed along with the licensed
440 software. For example, the license must not insist
441 that all other programs distributed on the same medium
442 must be free software.
444 <tag>Example Licenses
447 The "GPL," "BSD," and "Artistic" licenses are examples of
448 licenses that we consider <em>free</em>.
455 <heading>Archive areas</heading>
458 <heading>The main archive area</heading>
461 Every package in <em>main</em> must comply with the DFSG
462 (Debian Free Software Guidelines).
466 In addition, the packages in <em>main</em>
467 <list compact="compact">
469 must not require a package outside of <em>main</em>
470 for compilation or execution (thus, the package must
471 not declare a "Depends", "Recommends", or
472 "Build-Depends" relationship on a non-<em>main</em>
476 must not be so buggy that we refuse to support them,
480 must meet all policy requirements presented in this
489 <heading>The contrib archive area</heading>
492 Every package in <em>contrib</em> must comply with the DFSG.
496 In addition, the packages in <em>contrib</em>
497 <list compact="compact">
499 must not be so buggy that we refuse to support them,
503 must meet all policy requirements presented in this
511 Examples of packages which would be included in
512 <em>contrib</em> are:
513 <list compact="compact">
515 free packages which require <em>contrib</em>,
516 <em>non-free</em> packages or packages which are not
517 in our archive at all for compilation or execution,
521 wrapper packages or other sorts of free accessories for
528 <sect1 id="non-free">
529 <heading>The non-free archive area</heading>
532 Packages must be placed in <em>non-free</em> if they are
533 not compliant with the DFSG or are encumbered by patents
534 or other legal issues that make their distribution
539 In addition, the packages in <em>non-free</em>
540 <list compact="compact">
542 must not be so buggy that we refuse to support them,
546 must meet all policy requirements presented in this
547 manual that it is possible for them to meet.
549 It is possible that there are policy
550 requirements which the package is unable to
551 meet, for example, if the source is
552 unavailable. These situations will need to be
553 handled on a case-by-case basis.
562 <sect id="pkgcopyright">
563 <heading>Copyright considerations</heading>
566 Every package must be accompanied by a verbatim copy of
567 its copyright and distribution license in the file
568 <file>/usr/share/doc/<var>package</var>/copyright</file>
569 (see <ref id="copyrightfile"> for further details).
573 We reserve the right to restrict files from being included
574 anywhere in our archives if
575 <list compact="compact">
577 their use or distribution would break a law,
580 there is an ethical conflict in their distribution or
584 we would have to sign a license for them, or
587 their distribution would conflict with other project
594 Programs whose authors encourage the user to make
595 donations are fine for the main distribution, provided
596 that the authors do not claim that not donating is
597 immoral, unethical, illegal or something similar; in such
598 a case they must go in <em>non-free</em>.
602 Packages whose copyright permission notices (or patent
603 problems) do not even allow redistribution of binaries
604 only, and where no special permission has been obtained,
605 must not be placed on the Debian FTP site and its mirrors
610 Note that under international copyright law (this applies
611 in the United States, too), <em>no</em> distribution or
612 modification of a work is allowed without an explicit
613 notice saying so. Therefore a program without a copyright
614 notice <em>is</em> copyrighted and you may not do anything
615 to it without risking being sued! Likewise if a program
616 has a copyright notice but no statement saying what is
617 permitted then nothing is permitted.
621 Many authors are unaware of the problems that restrictive
622 copyrights (or lack of copyright notices) can cause for
623 the users of their supposedly-free software. It is often
624 worthwhile contacting such authors diplomatically to ask
625 them to modify their license terms. However, this can be a
626 politically difficult thing to do and you should ask for
627 advice on the <tt>debian-legal</tt> mailing list first, as
632 When in doubt about a copyright, send mail to
633 <email>debian-legal@lists.debian.org</email>. Be prepared
634 to provide us with the copyright statement. Software
635 covered by the GPL, public domain software and BSD-like
636 copyrights are safe; be wary of the phrases "commercial
637 use prohibited" and "distribution restricted".
641 <sect id="subsections">
642 <heading>Sections</heading>
645 The packages in the archive areas <em>main</em>,
646 <em>contrib</em> and <em>non-free</em> are grouped further into
647 <em>sections</em> to simplify handling.
651 The archive area and section for each package should be
652 specified in the package's <tt>Section</tt> control record (see
653 <ref id="f-Section">). However, the maintainer of the Debian
654 archive may override this selection to ensure the consistency of
655 the Debian distribution. The <tt>Section</tt> field should be
657 <list compact="compact">
659 <em>section</em> if the package is in the
660 <em>main</em> archive area,
663 <em>area/section</em> if the package is in
664 the <em>contrib</em> or <em>non-free</em>
671 The Debian archive maintainers provide the authoritative
672 list of sections. At present, they are:
673 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
674 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
675 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
676 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
677 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
678 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
679 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
680 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
681 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
682 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
683 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
684 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
685 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
690 <sect id="priorities">
691 <heading>Priorities</heading>
694 Each package should have a <em>priority</em> value, which is
695 included in the package's <em>control record</em>
696 (see <ref id="f-Priority">).
697 This information is used by the Debian package management tools to
698 separate high-priority packages from less-important packages.
702 The following <em>priority levels</em> are recognized by the
703 Debian package management tools.
705 <tag><tt>required</tt></tag>
707 Packages which are necessary for the proper
708 functioning of the system (usually, this means that
709 dpkg functionality depends on these packages).
710 Removing a <tt>required</tt> package may cause your
711 system to become totally broken and you may not even
712 be able to use <prgn>dpkg</prgn> to put things back,
713 so only do so if you know what you are doing. Systems
714 with only the <tt>required</tt> packages are probably
715 unusable, but they do have enough functionality to
716 allow the sysadmin to boot and install more software.
718 <tag><tt>important</tt></tag>
720 Important programs, including those which one would
721 expect to find on any Unix-like system. If the
722 expectation is that an experienced Unix person who
723 found it missing would say "What on earth is going on,
724 where is <prgn>foo</prgn>?", it must be an
725 <tt>important</tt> package.<footnote>
726 This is an important criterion because we are
727 trying to produce, amongst other things, a free
730 Other packages without which the system will not run
731 well or be usable must also have priority
732 <tt>important</tt>. This does
733 <em>not</em> include Emacs, the X Window System, TeX
734 or any other large applications. The
735 <tt>important</tt> packages are just a bare minimum of
736 commonly-expected and necessary tools.
738 <tag><tt>standard</tt></tag>
740 These packages provide a reasonably small but not too
741 limited character-mode system. This is what will be
742 installed by default if the user doesn't select anything
743 else. It doesn't include many large applications.
745 <tag><tt>optional</tt></tag>
747 (In a sense everything that isn't required is
748 optional, but that's not what is meant here.) This is
749 all the software that you might reasonably want to
750 install if you didn't know what it was and don't have
751 specialized requirements. This is a much larger system
752 and includes the X Window System, a full TeX
753 distribution, and many applications. Note that
754 optional packages should not conflict with each other.
756 <tag><tt>extra</tt></tag>
758 This contains all packages that conflict with others
759 with required, important, standard or optional
760 priorities, or are only likely to be useful if you
761 already know what they are or have specialized
762 requirements (such as packages containing only detached
769 Packages must not depend on packages with lower priority
770 values (excluding build-time dependencies). In order to
771 ensure this, the priorities of one or more packages may need
780 <heading>Binary packages</heading>
783 The Debian GNU/Linux distribution is based on the Debian
784 package management system, called <prgn>dpkg</prgn>. Thus,
785 all packages in the Debian distribution must be provided
786 in the <tt>.deb</tt> file format.
790 <heading>The package name</heading>
793 Every package must have a name that's unique within the Debian
798 The package name is included in the control field
799 <tt>Package</tt>, the format of which is described
800 in <ref id="f-Package">.
801 The package name is also included as a part of the file name
802 of the <tt>.deb</tt> file.
807 <heading>The version of a package</heading>
810 Every package has a version number recorded in its
811 <tt>Version</tt> control file field, described in
812 <ref id="f-Version">.
816 The package management system imposes an ordering on version
817 numbers, so that it can tell whether packages are being up- or
818 downgraded and so that package system front end applications
819 can tell whether a package it finds available is newer than
820 the one installed on the system. The version number format
821 has the most significant parts (as far as comparison is
822 concerned) at the beginning.
826 If an upstream package has problematic version numbers they
827 should be converted to a sane form for use in the
828 <tt>Version</tt> field.
832 <heading>Version numbers based on dates</heading>
835 In general, Debian packages should use the same version
836 numbers as the upstream sources.
840 However, in some cases where the upstream version number is
841 based on a date (e.g., a development "snapshot" release) the
842 package management system cannot handle these version
843 numbers without epochs. For example, dpkg will consider
844 "96May01" to be greater than "96Dec24".
848 To prevent having to use epochs for every new upstream
849 version, the date based portion of the version number
850 should be changed to the following format in such cases:
851 "19960501", "19961224". It is up to the maintainer whether
852 they want to bother the upstream maintainer to change
853 the version numbers upstream, too.
857 Note that other version formats based on dates which are
858 parsed correctly by the package management system should
859 <em>not</em> be changed.
863 Native Debian packages (i.e., packages which have been
864 written especially for Debian) whose version numbers include
865 dates should always use the "YYYYMMDD" format.
872 <heading>The maintainer of a package</heading>
875 Every package must have a Debian maintainer (the
876 maintainer may be one person or a group of people
877 reachable from a common email address, such as a mailing
878 list). The maintainer is responsible for ensuring that
879 the package is placed in the appropriate distributions.
883 The maintainer must be specified in the
884 <tt>Maintainer</tt> control field with their correct name
885 and a working email address. If one person maintains
886 several packages, they should try to avoid having
887 different forms of their name and email address in
888 the <tt>Maintainer</tt> fields of those packages.
892 The format of the <tt>Maintainer</tt> control field is
893 described in <ref id="f-Maintainer">.
897 If the maintainer of a package quits from the Debian
898 project, "Debian QA Group"
899 <email>packages@qa.debian.org</email> takes over the
900 maintainer-ship of the package until someone else
901 volunteers for that task. These packages are called
902 <em>orphaned packages</em>.<footnote>
903 The detailed procedure for doing this gracefully can
904 be found in the Debian Developer's Reference,
905 see <ref id="related">.
910 <sect id="descriptions">
911 <heading>The description of a package</heading>
914 Every Debian package must have an extended description
915 stored in the appropriate field of the control record.
916 The technical information about the format of the
917 <tt>Description</tt> field is in <ref id="f-Description">.
921 The description should describe the package (the program) to a
922 user (system administrator) who has never met it before so that
923 they have enough information to decide whether they want to
924 install it. This description should not just be copied verbatim
925 from the program's documentation.
929 Put important information first, both in the synopsis and
930 extended description. Sometimes only the first part of the
931 synopsis or of the description will be displayed. You can
932 assume that there will usually be a way to see the whole
933 extended description.
937 The description should also give information about the
938 significant dependencies and conflicts between this package
939 and others, so that the user knows why these dependencies and
940 conflicts have been declared.
944 Instructions for configuring or using the package should
945 not be included (that is what installation scripts,
946 manual pages, info files, etc., are for). Copyright
947 statements and other administrivia should not be included
948 either (that is what the copyright file is for).
951 <sect1 id="synopsis"><heading>The single line synopsis</heading>
954 The single line synopsis should be kept brief - certainly
959 Do not include the package name in the synopsis line. The
960 display software knows how to display this already, and you
961 do not need to state it. Remember that in many situations
962 the user may only see the synopsis line - make it as
963 informative as you can.
968 <sect1 id="extendeddesc"><heading>The extended description</heading>
971 Do not try to continue the single line synopsis into the
972 extended description. This will not work correctly when
973 the full description is displayed, and makes no sense
974 where only the summary (the single line synopsis) is
979 The extended description should describe what the package
980 does and how it relates to the rest of the system (in terms
981 of, for example, which subsystem it is which part of).
985 The description field needs to make sense to anyone, even
986 people who have no idea about any of the things the
987 package deals with.<footnote>
988 The blurb that comes with a program in its
989 announcements and/or <prgn>README</prgn> files is
990 rarely suitable for use in a description. It is
991 usually aimed at people who are already in the
992 community where the package is used.
1001 <heading>Dependencies</heading>
1004 Every package must specify the dependency information
1005 about other packages that are required for the first to
1010 For example, a dependency entry must be provided for any
1011 shared libraries required by a dynamically-linked executable
1012 binary in a package.
1016 Packages are not required to declare any dependencies they
1017 have on other packages which are marked <tt>Essential</tt>
1018 (see below), and should not do so unless they depend on a
1019 particular version of that package.<footnote>
1021 Essential is needed in part to avoid unresolvable dependency
1022 loops on upgrade. If packages add unnecessary dependencies
1023 on packages in this set, the chances that there
1024 <strong>will</strong> be an unresolvable dependency loop
1025 caused by forcing these Essential packages to be configured
1026 first before they need to be is greatly increased. It also
1027 increases the chances that frontends will be unable to
1028 <strong>calculate</strong> an upgrade path, even if one
1032 Also, functionality is rarely ever removed from the
1033 Essential set, but <em>packages</em> have been removed from
1034 the Essential set when the functionality moved to a
1035 different package. So depending on these packages <em>just
1036 in case</em> they stop being essential does way more harm
1043 Sometimes, a package requires another package to be installed
1044 <em>and</em> configured before it can be installed. In this
1045 case, you must specify a <tt>Pre-Depends</tt> entry for
1050 You should not specify a <tt>Pre-Depends</tt> entry for a
1051 package before this has been discussed on the
1052 <tt>debian-devel</tt> mailing list and a consensus about
1053 doing that has been reached.
1057 The format of the package interrelationship control fields is
1058 described in <ref id="relationships">.
1062 <sect id="virtual_pkg">
1063 <heading>Virtual packages</heading>
1066 Sometimes, there are several packages which offer
1067 more-or-less the same functionality. In this case, it's
1068 useful to define a <em>virtual package</em> whose name
1069 describes that common functionality. (The virtual
1070 packages only exist logically, not physically; that's why
1071 they are called <em>virtual</em>.) The packages with this
1072 particular function will then <em>provide</em> the virtual
1073 package. Thus, any other package requiring that function
1074 can simply depend on the virtual package without having to
1075 specify all possible packages individually.
1079 All packages should use virtual package names where
1080 appropriate, and arrange to create new ones if necessary.
1081 They should not use virtual package names (except privately,
1082 amongst a cooperating group of packages) unless they have
1083 been agreed upon and appear in the list of virtual package
1084 names. (See also <ref id="virtual">)
1088 The latest version of the authoritative list of virtual
1089 package names can be found in the <tt>debian-policy</tt> package.
1090 It is also available from the Debian web mirrors at
1091 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1092 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1096 The procedure for updating the list is described in the preface
1103 <heading>Base system</heading>
1106 The <tt>base system</tt> is a minimum subset of the Debian
1107 GNU/Linux system that is installed before everything else
1108 on a new system. Only very few packages are allowed to form
1109 part of the base system, in order to keep the required disk
1114 The base system consists of all those packages with priority
1115 <tt>required</tt> or <tt>important</tt>. Many of them will
1116 be tagged <tt>essential</tt> (see below).
1121 <heading>Essential packages</heading>
1124 Essential is defined as the minimal set of functionality that
1125 must be available and usable on the system at all times, even
1126 when packages are in an unconfigured (but unpacked) state.
1127 Packages are tagged <tt>essential</tt> for a system using the
1128 <tt>Essential</tt> control file field. The format of the
1129 <tt>Essential</tt> control field is described in <ref
1134 Since these packages cannot be easily removed (one has to
1135 specify an extra <em>force option</em> to
1136 <prgn>dpkg</prgn> to do so), this flag must not be used
1137 unless absolutely necessary. A shared library package
1138 must not be tagged <tt>essential</tt>; dependencies will
1139 prevent its premature removal, and we need to be able to
1140 remove it when it has been superseded.
1144 Since dpkg will not prevent upgrading of other packages
1145 while an <tt>essential</tt> package is in an unconfigured
1146 state, all <tt>essential</tt> packages must supply all of
1147 their core functionality even when unconfigured. If the
1148 package cannot satisfy this requirement it must not be
1149 tagged as essential, and any packages depending on this
1150 package must instead have explicit dependency fields as
1155 Maintainers should take great care in adding any programs,
1156 interfaces, or functionality to <tt>essential</tt> packages.
1157 Packages may assume that functionality provided by
1158 <tt>essential</tt> packages is always available without
1159 declaring explicit dependencies, which means that removing
1160 functionality from the Essential set is very difficult and is
1161 almost never done. Any capability added to an
1162 <tt>essential</tt> package therefore creates an obligation to
1163 support that capability as part of the Essential set in
1168 You must not tag any packages <tt>essential</tt> before
1169 this has been discussed on the <tt>debian-devel</tt>
1170 mailing list and a consensus about doing that has been
1175 <sect id="maintscripts">
1176 <heading>Maintainer Scripts</heading>
1179 The package installation scripts should avoid producing
1180 output which is unnecessary for the user to see and
1181 should rely on <prgn>dpkg</prgn> to stave off boredom on
1182 the part of a user installing many packages. This means,
1183 amongst other things, using the <tt>--quiet</tt> option on
1184 <prgn>install-info</prgn>.
1188 Errors which occur during the execution of an installation
1189 script must be checked and the installation must not
1190 continue after an error.
1194 Note that in general <ref id="scripts"> applies to package
1195 maintainer scripts, too.
1199 You should not use <prgn>dpkg-divert</prgn> on a file
1200 belonging to another package without consulting the
1201 maintainer of that package first.
1205 All packages which supply an instance of a common command
1206 name (or, in general, filename) should generally use
1207 <prgn>update-alternatives</prgn>, so that they may be
1208 installed together. If <prgn>update-alternatives</prgn>
1209 is not used, then each package must use
1210 <tt>Conflicts</tt> to ensure that other packages are
1211 de-installed. (In this case, it may be appropriate to
1212 specify a conflict against earlier versions of something
1213 that previously did not use
1214 <prgn>update-alternatives</prgn>; this is an exception to
1215 the usual rule that versioned conflicts should be
1219 <sect1 id="maintscriptprompt">
1220 <heading>Prompting in maintainer scripts</heading>
1222 Package maintainer scripts may prompt the user if
1223 necessary. Prompting must be done by communicating
1224 through a program, such as <prgn>debconf</prgn>, which
1225 conforms to the Debian Configuration Management
1226 Specification, version 2 or higher.
1230 Packages which are essential, or which are dependencies of
1231 essential packages, may fall back on another prompting method
1232 if no such interface is available when they are executed.
1236 The Debian Configuration Management Specification is included
1237 in the <file>debconf_specification</file> files in the
1238 <package>debian-policy</package> package.
1239 It is also available from the Debian web mirrors at
1240 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1241 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1245 Packages which use the Debian Configuration Management
1246 Specification may contain an additional
1247 <prgn>config</prgn> script and a <tt>templates</tt>
1248 file in their control archive<footnote>
1249 The control.tar.gz inside the .deb.
1250 See <manref name="deb" section="5">.
1252 The <prgn>config</prgn> script might be run before the
1253 <prgn>preinst</prgn> script, and before the package is unpacked
1254 or any of its dependencies or pre-dependencies are satisfied.
1255 Therefore it must work using only the tools present in
1256 <em>essential</em> packages.<footnote>
1257 <package>Debconf</package> or another tool that
1258 implements the Debian Configuration Management
1259 Specification will also be installed, and any
1260 versioned dependencies on it will be satisfied
1261 before preconfiguration begins.
1266 Packages which use the Debian Configuration Management
1267 Specification must allow for translation of their user-visible
1268 messages by using a gettext-based system such as the one
1269 provided by the <package>po-debconf</package> package.
1273 Packages should try to minimize the amount of prompting
1274 they need to do, and they should ensure that the user
1275 will only ever be asked each question once. This means
1276 that packages should try to use appropriate shared
1277 configuration files (such as <file>/etc/papersize</file> and
1278 <file>/etc/news/server</file>), and shared
1279 <package>debconf</package> variables rather than each
1280 prompting for their own list of required pieces of
1285 It also means that an upgrade should not ask the same
1286 questions again, unless the user has used
1287 <tt>dpkg --purge</tt> to remove the package's configuration.
1288 The answers to configuration questions should be stored in an
1289 appropriate place in <file>/etc</file> so that the user can
1290 modify them, and how this has been done should be
1295 If a package has a vitally important piece of
1296 information to pass to the user (such as "don't run me
1297 as I am, you must edit the following configuration files
1298 first or you risk your system emitting badly-formatted
1299 messages"), it should display this in the
1300 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1301 prompt the user to hit return to acknowledge the
1302 message. Copyright messages do not count as vitally
1303 important (they belong in
1304 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1305 neither do instructions on how to use a program (these
1306 should be in on-line documentation, where all the users
1311 Any necessary prompting should almost always be confined
1312 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1313 script. If it is done in the <prgn>postinst</prgn>, it
1314 should be protected with a conditional so that
1315 unnecessary prompting doesn't happen if a package's
1316 installation fails and the <prgn>postinst</prgn> is
1317 called with <tt>abort-upgrade</tt>,
1318 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1328 <heading>Source packages</heading>
1330 <sect id="standardsversion">
1331 <heading>Standards conformance</heading>
1334 Source packages should specify the most recent version number
1335 of this policy document with which your package complied
1336 when it was last updated.
1340 This information may be used to file bug reports
1341 automatically if your package becomes too much out of date.
1345 The version is specified in the <tt>Standards-Version</tt>
1347 The format of the <tt>Standards-Version</tt> field is
1348 described in <ref id="f-Standards-Version">.
1352 You should regularly, and especially if your package has
1353 become out of date, check for the newest Policy Manual
1354 available and update your package, if necessary. When your
1355 package complies with the new standards you should update the
1356 <tt>Standards-Version</tt> source package field and
1357 release it.<footnote>
1358 See the file <file>upgrading-checklist</file> for
1359 information about policy which has changed between
1360 different versions of this document.
1366 <sect id="pkg-relations">
1367 <heading>Package relationships</heading>
1370 Source packages should specify which binary packages they
1371 require to be installed or not to be installed in order to
1372 build correctly. For example, if building a package
1373 requires a certain compiler, then the compiler should be
1374 specified as a build-time dependency.
1378 It is not necessary to explicitly specify build-time
1379 relationships on a minimal set of packages that are always
1380 needed to compile, link and put in a Debian package a
1381 standard "Hello World!" program written in C or C++. The
1382 required packages are called <em>build-essential</em>, and
1383 an informational list can be found in
1384 <file>/usr/share/doc/build-essential/list</file> (which is
1385 contained in the <tt>build-essential</tt>
1388 <list compact="compact">
1390 This allows maintaining the list separately
1391 from the policy documents (the list does not
1392 need the kind of control that the policy
1396 Having a separate package allows one to install
1397 the build-essential packages on a machine, as
1398 well as allowing other packages such as tasks to
1399 require installation of the build-essential
1400 packages using the depends relation.
1403 The separate package allows bug reports against
1404 the list to be categorized separately from
1405 the policy management process in the BTS.
1412 When specifying the set of build-time dependencies, one
1413 should list only those packages explicitly required by the
1414 build. It is not necessary to list packages which are
1415 required merely because some other package in the list of
1416 build-time dependencies depends on them.<footnote>
1417 The reason for this is that dependencies change, and
1418 you should list all those packages, and <em>only</em>
1419 those packages that <em>you</em> need directly. What
1420 others need is their business. For example, if you
1421 only link against <file>libimlib</file>, you will need to
1422 build-depend on <package>libimlib2-dev</package> but
1423 not against any <tt>libjpeg*</tt> packages, even
1424 though <tt>libimlib2-dev</tt> currently depends on
1425 them: installation of <package>libimlib2-dev</package>
1426 will automatically ensure that all of its run-time
1427 dependencies are satisfied.
1432 If build-time dependencies are specified, it must be
1433 possible to build the package and produce working binaries
1434 on a system with only essential and build-essential
1435 packages installed and also those required to satisfy the
1436 build-time relationships (including any implied
1437 relationships). In particular, this means that version
1438 clauses should be used rigorously in build-time
1439 relationships so that one cannot produce bad or
1440 inconsistently configured packages when the relationships
1441 are properly satisfied.
1445 <ref id="relationships"> explains the technical details.
1450 <heading>Changes to the upstream sources</heading>
1453 If changes to the source code are made that are not
1454 specific to the needs of the Debian system, they should be
1455 sent to the upstream authors in whatever form they prefer
1456 so as to be included in the upstream version of the
1461 If you need to configure the package differently for
1462 Debian or for Linux, and the upstream source doesn't
1463 provide a way to do so, you should add such configuration
1464 facilities (for example, a new <prgn>autoconf</prgn> test
1465 or <tt>#define</tt>) and send the patch to the upstream
1466 authors, with the default set to the way they originally
1467 had it. You can then easily override the default in your
1468 <file>debian/rules</file> or wherever is appropriate.
1472 You should make sure that the <prgn>configure</prgn> utility
1473 detects the correct architecture specification string
1474 (refer to <ref id="arch-spec"> for details).
1478 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1479 <prgn>configure</prgn> scripts are used, you should edit the
1480 <file>.in</file> files rather than editing the
1481 <prgn>Makefile</prgn> directly. This allows the user to
1482 reconfigure the package if necessary. You should
1483 <em>not</em> configure the package and edit the generated
1484 <prgn>Makefile</prgn>! This makes it impossible for someone
1485 else to later reconfigure the package without losing the
1491 <sect id="dpkgchangelog">
1492 <heading>Debian changelog: <file>debian/changelog</file></heading>
1495 Changes in the Debian version of the package should be
1496 briefly explained in the Debian changelog file
1497 <file>debian/changelog</file>.<footnote>
1499 Mistakes in changelogs are usually best rectified by
1500 making a new changelog entry rather than "rewriting
1501 history" by editing old changelog entries.
1504 This includes modifications
1505 made in the Debian package compared to the upstream one
1506 as well as other changes and updates to the package.
1508 Although there is nothing stopping an author who is also
1509 the Debian maintainer from using this changelog for all
1510 their changes, it will have to be renamed if the Debian
1511 and upstream maintainers become different people. In such
1512 a case, however, it might be better to maintain the package
1513 as a non-native package.
1518 The format of the <file>debian/changelog</file> allows the
1519 package building tools to discover which version of the package
1520 is being built and find out other release-specific information.
1524 That format is a series of entries like this:
1526 <example compact="compact">
1527 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1529 [optional blank line(s), stripped]
1531 * <var>change details</var>
1532 <var>more change details</var>
1534 [blank line(s), included in output of dpkg-parsechangelog]
1536 * <var>even more change details</var>
1538 [optional blank line(s), stripped]
1540 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1545 <var>package</var> and <var>version</var> are the source
1546 package name and version number.
1550 <var>distribution(s)</var> lists the distributions where
1551 this version should be installed when it is uploaded - it
1552 is copied to the <tt>Distribution</tt> field in the
1553 <file>.changes</file> file. See <ref id="f-Distribution">.
1557 <var>urgency</var> is the value for the <tt>Urgency</tt>
1558 field in the <file>.changes</file> file for the upload
1559 (see <ref id="f-Urgency">). It is not possible to specify
1560 an urgency containing commas; commas are used to separate
1561 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1562 <prgn>dpkg</prgn> changelog format (though there is
1563 currently only one useful <var>keyword</var>,
1568 The change details may in fact be any series of lines
1569 starting with at least two spaces, but conventionally each
1570 change starts with an asterisk and a separating space and
1571 continuation lines are indented so as to bring them in
1572 line with the start of the text above. Blank lines may be
1573 used here to separate groups of changes, if desired.
1577 If this upload resolves bugs recorded in the Bug Tracking
1578 System (BTS), they may be automatically closed on the
1579 inclusion of this package into the Debian archive by
1580 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1581 in the change details.<footnote>
1582 To be precise, the string should match the following
1583 Perl regular expression:
1585 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1587 Then all of the bug numbers listed will be closed by the
1588 archive maintenance script (<prgn>katie</prgn>) using the
1589 <var>version</var> of the changelog entry.
1591 This information is conveyed via the <tt>Closes</tt> field
1592 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1596 The maintainer name and email address used in the changelog
1597 should be the details of the person uploading <em>this</em>
1598 version. They are <em>not</em> necessarily those of the
1599 usual package maintainer. The information here will be
1600 copied to the <tt>Changed-By</tt> field in the
1601 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1602 and then later used to send an acknowledgement when the
1603 upload has been installed.
1607 The <var>date</var> must be in RFC822 format<footnote>
1608 This is generated by <tt>date -R</tt>.
1609 </footnote>; it must include the time zone specified
1610 numerically, with the time zone name or abbreviation
1611 optionally present as a comment in parentheses.
1615 The first "title" line with the package name must start
1616 at the left hand margin. The "trailer" line with the
1617 maintainer and date details must be preceded by exactly
1618 one space. The maintainer details and the date must be
1619 separated by exactly two spaces.
1623 The entire changelog must be encoded in UTF-8.
1627 For more information on placement of the changelog files
1628 within binary packages, please see <ref id="changelogs">.
1632 <sect id="dpkgcopyright">
1633 <heading>Copyright: <file>debian/copyright</file></heading>
1635 Every package must be accompanied by a verbatim copy of
1636 its copyright and distribution license in the file
1637 <file>/usr/share/doc/<var>package</var>/copyright</file>
1638 (see <ref id="copyrightfile"> for further details). Also see
1639 <ref id="pkgcopyright"> for further considerations relayed
1640 to copyrights for packages.
1644 <heading>Error trapping in makefiles</heading>
1647 When <prgn>make</prgn> invokes a command in a makefile
1648 (including your package's upstream makefiles and
1649 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1650 means that <prgn>sh</prgn>'s usual bad error handling
1651 properties apply: if you include a miniature script as one
1652 of the commands in your makefile you'll find that if you
1653 don't do anything about it then errors are not detected
1654 and <prgn>make</prgn> will blithely continue after
1659 Every time you put more than one shell command (this
1660 includes using a loop) in a makefile command you
1661 must make sure that errors are trapped. For
1662 simple compound commands, such as changing directory and
1663 then running a program, using <tt>&&</tt> rather
1664 than semicolon as a command separator is sufficient. For
1665 more complex commands including most loops and
1666 conditionals you should include a separate <tt>set -e</tt>
1667 command at the start of every makefile command that's
1668 actually one of these miniature shell scripts.
1672 <sect id="timestamps">
1673 <heading>Time Stamps</heading>
1675 Maintainers should preserve the modification times of the
1676 upstream source files in a package, as far as is reasonably
1678 The rationale is that there is some information conveyed
1679 by knowing the age of the file, for example, you could
1680 recognize that some documentation is very old by looking
1681 at the modification time, so it would be nice if the
1682 modification time of the upstream source would be
1688 <sect id="restrictions">
1689 <heading>Restrictions on objects in source packages</heading>
1692 The source package may not contain any hard links<footnote>
1694 This is not currently detected when building source
1695 packages, but only when extracting
1699 Hard links may be permitted at some point in the
1700 future, but would require a fair amount of
1703 </footnote>, device special files, sockets or setuid or
1704 setgid files.<footnote>
1705 Setgid directories are allowed.
1710 <sect id="debianrules">
1711 <heading>Main building script: <file>debian/rules</file></heading>
1714 This file must be an executable makefile, and contains the
1715 package-specific recipes for compiling the package and
1716 building binary package(s) from the source.
1720 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1721 so that it can be invoked by saying its name rather than
1722 invoking <prgn>make</prgn> explicitly.
1726 Since an interactive <file>debian/rules</file> script makes it
1727 impossible to auto-compile that package and also makes it
1728 hard for other people to reproduce the same binary
1729 package, all <em>required targets</em> MUST be
1730 non-interactive. At a minimum, required targets are the
1731 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1732 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1733 <em>binary-indep</em>, and <em>build</em>. It also follows
1734 that any target that these targets depend on must also be
1739 The targets are as follows (required unless stated otherwise):
1741 <tag><tt>build</tt></tag>
1744 The <tt>build</tt> target should perform all the
1745 configuration and compilation of the package.
1746 If a package has an interactive pre-build
1747 configuration routine, the Debianized source package
1748 must either be built after this has taken place (so
1749 that the binary package can be built without rerunning
1750 the configuration) or the configuration routine
1751 modified to become non-interactive. (The latter is
1752 preferable if there are architecture-specific features
1753 detected by the configuration routine.)
1757 For some packages, notably ones where the same
1758 source tree is compiled in different ways to produce
1759 two binary packages, the <tt>build</tt> target
1760 does not make much sense. For these packages it is
1761 good enough to provide two (or more) targets
1762 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1763 for each of the ways of building the package, and a
1764 <tt>build</tt> target that does nothing. The
1765 <tt>binary</tt> target will have to build the
1766 package in each of the possible ways and make the
1767 binary package out of each.
1771 The <tt>build</tt> target must not do anything
1772 that might require root privilege.
1776 The <tt>build</tt> target may need to run the
1777 <tt>clean</tt> target first - see below.
1781 When a package has a configuration and build routine
1782 which takes a long time, or when the makefiles are
1783 poorly designed, or when <tt>build</tt> needs to
1784 run <tt>clean</tt> first, it is a good idea to
1785 <tt>touch build</tt> when the build process is
1786 complete. This will ensure that if <tt>debian/rules
1787 build</tt> is run again it will not rebuild the whole
1789 Another common way to do this is for <tt>build</tt>
1790 to depend on <prgn>build-stamp</prgn> and to do
1791 nothing else, and for the <prgn>build-stamp</prgn>
1792 target to do the building and to <tt>touch
1793 build-stamp</tt> on completion. This is
1794 especially useful if the build routine creates a
1795 file or directory called <tt>build</tt>; in such a
1796 case, <tt>build</tt> will need to be listed as
1797 a phony target (i.e., as a dependency of the
1798 <tt>.PHONY</tt> target). See the documentation of
1799 <prgn>make</prgn> for more information on phony
1805 <tag><tt>build-arch</tt> (optional),
1806 <tt>build-indep</tt> (optional)
1810 A package may also provide both of the targets
1811 <tt>build-arch</tt> and <tt>build-indep</tt>.
1812 The <tt>build-arch</tt> target, if provided, should
1813 perform all the configuration and compilation required
1814 for producing all architecture-dependant binary packages
1815 (those packages for which the body of the
1816 <tt>Architecture</tt> field in <tt>debian/control</tt>
1817 is not <tt>all</tt>).
1818 Similarly, the <tt>build-indep</tt> target, if
1819 provided, should perform all the configuration and
1820 compilation required for producing all
1821 architecture-independent binary packages
1822 (those packages for which the body of the
1823 <tt>Architecture</tt> field in <tt>debian/control</tt>
1825 The <tt>build</tt> target should depend on those of the
1826 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1827 are provided in the rules file.
1831 If one or both of the targets <tt>build-arch</tt> and
1832 <tt>build-indep</tt> are not provided, then invoking
1833 <file>debian/rules</file> with one of the not-provided
1834 targets as arguments should produce a exit status code
1835 of 2. Usually this is provided automatically by make
1836 if the target is missing.
1840 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1841 must not do anything that might require root privilege.
1845 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1846 <tt>binary-indep</tt>
1850 The <tt>binary</tt> target must be all that is
1851 necessary for the user to build the binary package(s)
1852 produced from this source package. It is
1853 split into two parts: <prgn>binary-arch</prgn> builds
1854 the binary packages which are specific to a particular
1855 architecture, and <tt>binary-indep</tt> builds
1856 those which are not.
1859 <tt>binary</tt> may be (and commonly is) a target with
1860 no commands which simply depends on
1861 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1864 Both <tt>binary-*</tt> targets should depend on the
1865 <tt>build</tt> target, or on the appropriate
1866 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1867 provided, so that the package is built if it has not
1868 been already. It should then create the relevant
1869 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1870 make their control files and <prgn>dpkg-deb</prgn> to
1871 build them and place them in the parent of the top
1876 Both the <tt>binary-arch</tt> and
1877 <tt>binary-indep</tt> targets <em>must</em> exist.
1878 If one of them has nothing to do (which will always be
1879 the case if the source generates only a single binary
1880 package, whether architecture-dependent or not), it
1881 must still exist and must always succeed.
1885 The <tt>binary</tt> targets must be invoked as
1887 The <prgn>fakeroot</prgn> package often allows one
1888 to build a package correctly even without being
1894 <tag><tt>clean</tt></tag>
1897 This must undo any effects that the <tt>build</tt>
1898 and <tt>binary</tt> targets may have had, except
1899 that it should leave alone any output files created in
1900 the parent directory by a run of a <tt>binary</tt>
1905 If a <tt>build</tt> file is touched at the end of
1906 the <tt>build</tt> target, as suggested above, it
1907 should be removed as the first action that
1908 <tt>clean</tt> performs, so that running
1909 <tt>build</tt> again after an interrupted
1910 <tt>clean</tt> doesn't think that everything is
1915 The <tt>clean</tt> target may need to be
1916 invoked as root if <tt>binary</tt> has been
1917 invoked since the last <tt>clean</tt>, or if
1918 <tt>build</tt> has been invoked as root (since
1919 <tt>build</tt> may create directories, for
1924 <tag><tt>get-orig-source</tt> (optional)</tag>
1927 This target fetches the most recent version of the
1928 original source package from a canonical archive site
1929 (via FTP or WWW, for example), does any necessary
1930 rearrangement to turn it into the original source
1931 tar file format described below, and leaves it in the
1936 This target may be invoked in any directory, and
1937 should take care to clean up any temporary files it
1942 This target is optional, but providing it if
1943 possible is a good idea.
1947 <tag><tt>patch</tt> (optional)</tag>
1950 This target performs whatever additional actions are
1951 required to make the source ready for editing (unpacking
1952 additional upstream archives, applying patches, etc.).
1953 It is recommended to be implemented for any package where
1954 <tt>dpkg-source -x</tt> does not result in source ready
1955 for additional modification. See
1956 <ref id="readmesource">.
1962 The <tt>build</tt>, <tt>binary</tt> and
1963 <tt>clean</tt> targets must be invoked with the current
1964 directory being the package's top-level directory.
1969 Additional targets may exist in <file>debian/rules</file>,
1970 either as published or undocumented interfaces or for the
1971 package's internal use.
1975 The architectures we build on and build for are determined
1976 by <prgn>make</prgn> variables using the utility
1977 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1978 You can determine the
1979 Debian architecture and the GNU style architecture
1980 specification string for the build machine (the machine type
1981 we are building on) as well as for the host machine (the
1982 machine type we are building for). Here is a list of
1983 supported <prgn>make</prgn> variables:
1984 <list compact="compact">
1986 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1989 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1990 specification string)
1993 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
1994 <tt>DEB_*_GNU_TYPE</tt>)
1997 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1998 <tt>DEB_*_GNU_TYPE</tt>)
2000 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2001 the build machine or <tt>HOST</tt> for specification of the
2006 Backward compatibility can be provided in the rules file
2007 by setting the needed variables to suitable default
2008 values; please refer to the documentation of
2009 <prgn>dpkg-architecture</prgn> for details.
2013 It is important to understand that the <tt>DEB_*_ARCH</tt>
2014 string only determines which Debian architecture we are
2015 building on or for. It should not be used to get the CPU
2016 or system information; the GNU style variables should be
2020 <sect1 id="debianrules-options">
2021 <heading><file>debian/rules</file> and
2022 <tt>DEB_BUILD_OPTIONS</tt></heading>
2025 Supporting the standardized environment variable
2026 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2027 contain several flags to change how a package is compiled and
2028 built. Each flag must be in the form <var>flag</var> or
2029 <var>flag</var>=<var>options</var>. If multiple flags are
2030 given, they must be separated by whitespace.<footnote>
2031 Some packages support any delimiter, but whitespace is the
2032 easiest to parse inside a makefile and avoids ambiguity with
2033 flag values that contain commas.
2035 <var>flag</var> must start with a lowercase letter
2036 (<tt>a-z</tt>) and consist only of lowercase letters,
2037 numbers (<tt>0-9</tt>), and the characters
2038 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2039 <var>options</var> must not contain whitespace. The same
2040 tag should not be given multiple times with conflicting
2041 values. Package maintainers may assume that
2042 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2046 The meaning of the following tags has been standardized:
2050 This tag says to not run any build-time test suite
2051 provided by the package.
2055 The presence of this tag means that the package should
2056 be compiled with a minimum of optimization. For C
2057 programs, it is best to add <tt>-O0</tt> to
2058 <tt>CFLAGS</tt> (although this is usually the default).
2059 Some programs might fail to build or run at this level
2060 of optimization; it may be necessary to use
2061 <tt>-O1</tt>, for example.
2065 This tag means that the debugging symbols should not be
2066 stripped from the binary during installation, so that
2067 debugging information may be included in the package.
2069 <tag>parallel=n</tag>
2071 This tag means that the package should be built using up
2072 to <tt>n</tt> parallel processes if the package build
2073 system supports this.<footnote>
2074 Packages built with <tt>make</tt> can often implement
2075 this by passing the <tt>-j</tt><var>n</var> option to
2078 If the package build system does not support parallel
2079 builds, this string must be ignored. If the package
2080 build system only supports a lower level of concurrency
2081 than <var>n</var>, the package should be built using as
2082 many parallel processes as the package build system
2083 supports. It is up to the package maintainer to decide
2084 whether the package build times are long enough and the
2085 package build system is robust enough to make supporting
2086 parallel builds worthwhile.
2092 Unknown flags must be ignored by <file>debian/rules</file>.
2096 The following makefile snippet is an example of how one may
2097 implement the build options; you will probably have to
2098 massage this example in order to make it work for your
2100 <example compact="compact">
2103 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2104 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2105 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2106 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2108 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2113 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2114 INSTALL_PROGRAM += -s
2116 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2117 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2118 MAKEFLAGS += -j$(NUMJOBS)
2123 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2124 # Code to run the package test suite.
2131 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2132 <sect id="substvars">
2133 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2136 When <prgn>dpkg-gencontrol</prgn>,
2137 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2138 generate control files they perform variable substitutions
2139 on their output just before writing it. Variable
2140 substitutions have the form <tt>${<var>variable</var>}</tt>.
2141 The optional file <file>debian/substvars</file> contains
2142 variable substitutions to be used; variables can also be set
2143 directly from <file>debian/rules</file> using the <tt>-V</tt>
2144 option to the source packaging commands, and certain
2145 predefined variables are also available.
2149 The <file>debian/substvars</file> file is usually generated and
2150 modified dynamically by <file>debian/rules</file> targets, in
2151 which case it must be removed by the <tt>clean</tt> target.
2155 See <manref name="deb-substvars" section="5"> for full
2156 details about source variable substitutions, including the
2157 format of <file>debian/substvars</file>.</p>
2160 <sect id="debianwatch">
2161 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2164 This is an optional, recommended control file for the
2165 <tt>uscan</tt> utility which defines how to automatically
2166 scan ftp or http sites for newly available updates of the
2167 package. This is used by <url id="
2168 http://dehs.alioth.debian.org/"> and other Debian QA tools
2169 to help with quality control and maintenance of the
2170 distribution as a whole.
2175 <sect id="debianfiles">
2176 <heading>Generated files list: <file>debian/files</file></heading>
2179 This file is not a permanent part of the source tree; it
2180 is used while building packages to record which files are
2181 being generated. <prgn>dpkg-genchanges</prgn> uses it
2182 when it generates a <file>.changes</file> file.
2186 It should not exist in a shipped source package, and so it
2187 (and any backup files or temporary files such as
2188 <file>files.new</file><footnote>
2189 <file>files.new</file> is used as a temporary file by
2190 <prgn>dpkg-gencontrol</prgn> and
2191 <prgn>dpkg-distaddfile</prgn> - they write a new
2192 version of <tt>files</tt> here before renaming it,
2193 to avoid leaving a corrupted copy if an error
2195 </footnote>) should be removed by the
2196 <tt>clean</tt> target. It may also be wise to
2197 ensure a fresh start by emptying or removing it at the
2198 start of the <tt>binary</tt> target.
2202 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2203 package, it adds an entry to <file>debian/files</file> for the
2204 <file>.deb</file> file that will be created when <tt>dpkg-deb
2205 --build</tt> is run for that binary package. So for most
2206 packages all that needs to be done with this file is to
2207 delete it in the <tt>clean</tt> target.
2211 If a package upload includes files besides the source
2212 package and any binary packages whose control files were
2213 made with <prgn>dpkg-gencontrol</prgn> then they should be
2214 placed in the parent of the package's top-level directory
2215 and <prgn>dpkg-distaddfile</prgn> should be called to add
2216 the file to the list in <file>debian/files</file>.</p>
2219 <sect id="embeddedfiles">
2220 <heading>Convenience copies of code</heading>
2223 Some software packages include in their distribution convenience
2224 copies of code from other software packages, generally so that
2225 users compiling from source don't have to download multiple
2226 packages. Debian packages should not make use of these
2227 convenience copies unless the included package is explicitly
2228 intended to be used in this way.<footnote>
2229 For example, parts of the GNU build system work like this.
2231 If the included code is already in the Debian archive in the
2232 form of a library, the Debian packaging should ensure that
2233 binary packages reference the libraries already in Debian and
2234 the convenience copy is not used. If the included code is not
2235 already in Debian, it should be packaged separately as a
2236 prerequisite if possible.
2238 Having multiple copies of the same code in Debian is
2239 inefficient, often creates either static linking or shared
2240 library conflicts, and, most importantly, increases the
2241 difficulty of handling security vulnerabilities in the
2247 <sect id="readmesource">
2248 <heading>Source package handling:
2249 <file>debian/README.source</file></heading>
2252 If running <prgn>dpkg-source -x</prgn> on a source package
2253 doesn't produce the source of the package, ready for editing,
2254 and allow one to make changes and run
2255 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2256 without taking any additional steps, creating a
2257 <file>debian/README.source</file> documentation file is
2258 recommended. This file should explain how to do all of the
2261 <item>Generate the fully patched source, in a form ready for
2262 editing, that would be built to create Debian
2263 packages. Doing this with a <tt>patch</tt> target in
2264 <file>debian/rules</file> is recommended; see
2265 <ref id="debianrules">.</item>
2266 <item>Modify the source and save those modifications so that
2267 they will be applied when building the package.</item>
2268 <item>Remove source modifications that are currently being
2269 applied when building the package.</item>
2270 <item>Optionally, document what steps are necessary to
2271 upgrade the Debian source package to a new upstream version,
2272 if applicable.</item>
2274 This explanation should include specific commands and mention
2275 any additional required Debian packages. It should not assume
2276 familiarity with any specific Debian packaging system or patch
2281 This explanation may refer to a documentation file installed by
2282 one of the package's build dependencies provided that the
2283 referenced documentation clearly explains these tasks and is not
2284 a general reference manual.
2288 <file>debian/README.source</file> may also include any other
2289 information that would be helpful to someone modifying the
2290 source package. Even if the package doesn't fit the above
2291 description, maintainers are encouraged to document in a
2292 <file>debian/README.source</file> file any source package with a
2293 particularly complex or unintuitive source layout or build
2294 system (for example, a package that builds the same source
2295 multiple times to generate different binary packages).
2301 <chapt id="controlfields">
2302 <heading>Control files and their fields</heading>
2305 The package management system manipulates data represented in
2306 a common format, known as <em>control data</em>, stored in
2307 <em>control files</em>.
2308 Control files are used for source packages, binary packages and
2309 the <file>.changes</file> files which control the installation
2310 of uploaded files<footnote>
2311 <prgn>dpkg</prgn>'s internal databases are in a similar
2316 <sect id="controlsyntax">
2317 <heading>Syntax of control files</heading>
2320 A control file consists of one or more paragraphs of
2322 The paragraphs are also sometimes referred to as stanzas.
2324 The paragraphs are separated by blank lines. Some control
2325 files allow only one paragraph; others allow several, in
2326 which case each paragraph usually refers to a different
2327 package. (For example, in source packages, the first
2328 paragraph refers to the source package, and later paragraphs
2329 refer to binary packages generated from the source.)
2333 Each paragraph consists of a series of data fields; each
2334 field consists of the field name, followed by a colon and
2335 then the data/value associated with that field. It ends at
2336 the end of the (logical) line. Horizontal whitespace
2337 (spaces and tabs) may occur immediately before or after the
2338 value and is ignored there; it is conventional to put a
2339 single space after the colon. For example, a field might
2341 <example compact="compact">
2344 the field name is <tt>Package</tt> and the field value
2349 Many fields' values may span several lines; in this case
2350 each continuation line must start with a space or a tab.
2351 Any trailing spaces or tabs at the end of individual
2352 lines of a field value are ignored.
2356 In fields where it is specified that lines may not wrap,
2357 only a single line of data is allowed and whitespace is not
2358 significant in a field body. Whitespace must not appear
2359 inside names (of packages, architectures, files or anything
2360 else) or version numbers, or between the characters of
2361 multi-character version relationships.
2365 Field names are not case-sensitive, but it is usual to
2366 capitalize the field names using mixed case as shown below.
2370 Blank lines, or lines consisting only of spaces and tabs,
2371 are not allowed within field values or between fields - that
2372 would mean a new paragraph.
2376 All control files must be encoded in UTF-8.
2380 <sect id="sourcecontrolfiles">
2381 <heading>Source package control files -- <file>debian/control</file></heading>
2384 The <file>debian/control</file> file contains the most vital
2385 (and version-independent) information about the source package
2386 and about the binary packages it creates.
2390 The first paragraph of the control file contains information about
2391 the source package in general. The subsequent sets each describe a
2392 binary package that the source tree builds.
2396 The fields in the general paragraph (the first one, for the source
2399 <list compact="compact">
2400 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2401 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2402 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2403 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2404 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2405 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2406 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2407 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2412 The fields in the binary package paragraphs are:
2414 <list compact="compact">
2415 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2416 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2417 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2418 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2419 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2420 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2421 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2422 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2427 The syntax and semantics of the fields are described below.
2433 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2434 generate control files for binary packages (see below), by
2435 <prgn>dpkg-genchanges</prgn> to generate the
2436 <tt>.changes</tt> file to accompany the upload, and by
2437 <prgn>dpkg-source</prgn> when it creates the
2438 <file>.dsc</file> source control file as part of a source
2439 archive. Many fields are permitted to span multiple lines in
2440 <file>debian/control</file> but not in any other control
2441 file. These tools are responsible for removing the line
2442 breaks from such fields when using fields from
2443 <file>debian/control</file> to generate other control files.
2447 The fields here may contain variable references - their
2448 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2449 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2450 when they generate output control files.
2451 See <ref id="substvars"> for details.
2455 In addition to the control file syntax described <qref
2456 id="controlsyntax">above</qref>, this file may also contain
2457 comment lines starting with <tt>#</tt> without any preceding
2458 whitespace. All such lines are ignored, even in the middle of
2459 continuation lines for a multiline field, and do not end a
2465 <sect id="binarycontrolfiles">
2466 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2469 The <file>DEBIAN/control</file> file contains the most vital
2470 (and version-dependent) information about a binary package.
2474 The fields in this file are:
2476 <list compact="compact">
2477 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2478 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2479 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2480 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2481 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2482 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2483 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2484 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2485 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2486 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2487 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2488 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2493 <sect id="debiansourcecontrolfiles">
2494 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2497 This file contains a series of fields, identified and
2498 separated just like the fields in the control file of
2499 a binary package. The fields are listed below; their
2500 syntax is described above, in <ref id="pkg-controlfields">.
2502 <list compact="compact">
2503 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2504 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2505 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2506 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2507 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2508 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2509 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2510 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2511 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2512 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2513 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2518 The source package control file is generated by
2519 <prgn>dpkg-source</prgn> when it builds the source
2520 archive, from other files in the source package,
2521 described above. When unpacking, it is checked against
2522 the files and directories in the other parts of the
2528 <sect id="debianchangesfiles">
2529 <heading>Debian changes files -- <file>.changes</file></heading>
2532 The .changes files are used by the Debian archive maintenance
2533 software to process updates to packages. They contain one
2534 paragraph which contains information from the
2535 <tt>debian/control</tt> file and other data about the
2536 source package gathered via <tt>debian/changelog</tt>
2537 and <tt>debian/rules</tt>.
2541 The fields in this file are:
2543 <list compact="compact">
2544 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2545 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2546 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2547 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2548 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2549 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2550 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2551 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2552 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2553 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2554 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2555 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2556 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2557 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2562 <sect id="controlfieldslist">
2563 <heading>List of fields</heading>
2565 <sect1 id="f-Source">
2566 <heading><tt>Source</tt></heading>
2569 This field identifies the source package name.
2573 In <file>debian/control</file> or a <file>.dsc</file> file,
2574 this field must contain only the name of the source package.
2578 In a binary package control file or a <file>.changes</file>
2579 file, the source package name may be followed by a version
2580 number in parentheses<footnote>
2581 It is customary to leave a space after the package name
2582 if a version number is specified.
2584 This version number may be omitted (and is, by
2585 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2586 the <tt>Version</tt> field of the binary package in
2587 question. The field itself may be omitted from a binary
2588 package control file when the source package has the same
2589 name and version as the binary package.
2593 Package names must consist only of lower case letters
2594 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2595 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2596 They must be at least two characters long and must start
2597 with an alphanumeric character.
2601 <sect1 id="f-Maintainer">
2602 <heading><tt>Maintainer</tt></heading>
2605 The package maintainer's name and email address. The name
2606 should come first, then the email address inside angle
2607 brackets <tt><></tt> (in RFC822 format).
2611 If the maintainer's name contains a full stop then the
2612 whole field will not work directly as an email address due
2613 to a misfeature in the syntax specified in RFC822; a
2614 program using this field as an address must check for this
2615 and correct the problem if necessary (for example by
2616 putting the name in round brackets and moving it to the
2617 end, and bringing the email address forward).
2621 <sect1 id="f-Uploaders">
2622 <heading><tt>Uploaders</tt></heading>
2625 List of the names and email addresses of co-maintainers of
2626 the package, if any. If the package has other maintainers
2627 beside the one named in the
2628 <qref id="f-Maintainer">Maintainer field</qref>, their
2629 names and email addresses should be listed here. The
2630 format is the same as that of the Maintainer tag, and
2631 multiple entries should be comma separated. Currently,
2632 this field is restricted to a single line of data. This
2633 is an optional field.
2636 Any parser that interprets the Uploaders field in
2637 <file>debian/control</file> must permit it to span multiple
2638 lines. Line breaks in an Uploaders field that spans multiple
2639 lines are not significant and the semantics of the field are
2640 the same as if the line breaks had not been present.
2644 <sect1 id="f-Changed-By">
2645 <heading><tt>Changed-By</tt></heading>
2648 The name and email address of the person who changed the
2649 said package. Usually the name of the maintainer.
2650 All the rules for the Maintainer field apply here, too.
2654 <sect1 id="f-Section">
2655 <heading><tt>Section</tt></heading>
2658 This field specifies an application area into which the package
2659 has been classified. See <ref id="subsections">.
2663 When it appears in the <file>debian/control</file> file,
2664 it gives the value for the subfield of the same name in
2665 the <tt>Files</tt> field of the <file>.changes</file> file.
2666 It also gives the default for the same field in the binary
2671 <sect1 id="f-Priority">
2672 <heading><tt>Priority</tt></heading>
2675 This field represents how important that it is that the user
2676 have the package installed. See <ref id="priorities">.
2680 When it appears in the <file>debian/control</file> file,
2681 it gives the value for the subfield of the same name in
2682 the <tt>Files</tt> field of the <file>.changes</file> file.
2683 It also gives the default for the same field in the binary
2688 <sect1 id="f-Package">
2689 <heading><tt>Package</tt></heading>
2692 The name of the binary package.
2696 Package names must consist only of lower case letters
2697 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2698 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2699 They must be at least two characters long and must start
2700 with an alphanumeric character.
2704 <sect1 id="f-Architecture">
2705 <heading><tt>Architecture</tt></heading>
2708 Depending on context and the control file used, the
2709 <tt>Architecture</tt> field can include the following sets of
2712 <item>A unique single word identifying a Debian machine
2713 architecture as described in <ref id="arch-spec">.
2714 <item><tt>all</tt>, which indicates an
2715 architecture-independent package.
2716 <item><tt>any</tt>, which indicates a package available
2717 for building on any architecture.
2718 <item><tt>source</tt>, which indicates a source package.
2723 In the main <file>debian/control</file> file in the source
2724 package, this field may contain the special value
2725 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2726 architectures separated by spaces. If <tt>any</tt> or
2727 <tt>all</tt> appear, they must be the entire contents of the
2728 field. Most packages will use either <tt>any</tt> or
2729 <tt>all</tt>. Specifying a specific list of architectures is
2730 for the minority of cases where a program is not portable or
2731 is not useful on some architectures, and where possible the
2732 program should be made portable instead.
2736 In the source package control file <file>.dsc</file>, this
2737 field may contain either the special value <tt>any</tt> or a
2738 list of architectures separated by spaces. If a list is given,
2739 it may include (or consist solely of) the special value
2740 <tt>all</tt>. In other words, in <file>.dsc</file> files
2741 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2742 in combination with specific architectures. The
2743 <tt>Architecture</tt> field in the source package control file
2744 <file>.dsc</file> is generally constructed from the
2745 <tt>Architecture</tt> fields in the
2746 <file>debian/control</file> in the source package.
2750 Specifying <tt>any</tt> indicates that the source package
2751 isn't dependent on any particular architecture and should
2752 compile fine on any one. The produced binary package(s)
2753 will either be specific to whatever the current build
2754 architecture is or will be architecture-independent.
2758 Specifying only <tt>all</tt> indicates that the source package
2759 will only build architecture-independent packages. If this is
2760 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2761 <tt>any</tt> implies that the source package will build at
2762 least one architecture-dependent package.
2766 Specifying a list of architectures indicates that the source
2767 will build an architecture-dependent package, and will only
2768 work correctly on the listed architectures. If the source
2769 package also builds at least one architecture-independent
2770 package, <tt>all</tt> will also be included in the list.
2774 In a <file>.changes</file> file, the <tt>Architecture</tt>
2775 field lists the architecture(s) of the package(s)
2776 currently being uploaded. This will be a list; if the
2777 source for the package is also being uploaded, the special
2778 entry <tt>source</tt> is also present. <tt>all</tt> will be
2779 present if any architecture-independent packages are being
2780 uploaded. <tt>any</tt> may never occur in the
2781 <tt>Architecture</tt> field in the <file>.changes</file>
2786 See <ref id="debianrules"> for information how to get the
2787 architecture for the build process.
2791 <sect1 id="f-Essential">
2792 <heading><tt>Essential</tt></heading>
2795 This is a boolean field which may occur only in the
2796 control file of a binary package or in a per-package fields
2797 paragraph of a main source control data file.
2801 If set to <tt>yes</tt> then the package management system
2802 will refuse to remove the package (upgrading and replacing
2803 it is still possible). The other possible value is <tt>no</tt>,
2804 which is the same as not having the field at all.
2809 <heading>Package interrelationship fields:
2810 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2811 <tt>Recommends</tt>, <tt>Suggests</tt>,
2812 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2813 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2817 These fields describe the package's relationships with
2818 other packages. Their syntax and semantics are described
2819 in <ref id="relationships">.</p>
2822 <sect1 id="f-Standards-Version">
2823 <heading><tt>Standards-Version</tt></heading>
2826 The most recent version of the standards (the policy
2827 manual and associated texts) with which the package
2832 The version number has four components: major and minor
2833 version number and major and minor patch level. When the
2834 standards change in a way that requires every package to
2835 change the major number will be changed. Significant
2836 changes that will require work in many packages will be
2837 signaled by a change to the minor number. The major patch
2838 level will be changed for any change to the meaning of the
2839 standards, however small; the minor patch level will be
2840 changed when only cosmetic, typographical or other edits
2841 are made which neither change the meaning of the document
2842 nor affect the contents of packages.
2846 Thus only the first three components of the policy version
2847 are significant in the <em>Standards-Version</em> control
2848 field, and so either these three components or the all
2849 four components may be specified.<footnote>
2850 In the past, people specified the full version number
2851 in the Standards-Version field, for example "2.3.0.0".
2852 Since minor patch-level changes don't introduce new
2853 policy, it was thought it would be better to relax
2854 policy and only require the first 3 components to be
2855 specified, in this example "2.3.0". All four
2856 components may still be used if someone wishes to do so.
2862 <sect1 id="f-Version">
2863 <heading><tt>Version</tt></heading>
2866 The version number of a package. The format is:
2867 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2871 The three components here are:
2873 <tag><var>epoch</var></tag>
2876 This is a single (generally small) unsigned integer. It
2877 may be omitted, in which case zero is assumed. If it is
2878 omitted then the <var>upstream_version</var> may not
2883 It is provided to allow mistakes in the version numbers
2884 of older versions of a package, and also a package's
2885 previous version numbering schemes, to be left behind.
2889 <tag><var>upstream_version</var></tag>
2892 This is the main part of the version number. It is
2893 usually the version number of the original ("upstream")
2894 package from which the <file>.deb</file> file has been made,
2895 if this is applicable. Usually this will be in the same
2896 format as that specified by the upstream author(s);
2897 however, it may need to be reformatted to fit into the
2898 package management system's format and comparison
2903 The comparison behavior of the package management system
2904 with respect to the <var>upstream_version</var> is
2905 described below. The <var>upstream_version</var>
2906 portion of the version number is mandatory.
2910 The <var>upstream_version</var> may contain only
2911 alphanumerics<footnote>
2912 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2914 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2915 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2916 tilde) and should start with a digit. If there is no
2917 <var>debian_revision</var> then hyphens are not allowed;
2918 if there is no <var>epoch</var> then colons are not
2923 <tag><var>debian_revision</var></tag>
2926 This part of the version number specifies the version of
2927 the Debian package based on the upstream version. It
2928 may contain only alphanumerics and the characters
2929 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2930 tilde) and is compared in the same way as the
2931 <var>upstream_version</var> is.
2935 It is optional; if it isn't present then the
2936 <var>upstream_version</var> may not contain a hyphen.
2937 This format represents the case where a piece of
2938 software was written specifically to be turned into a
2939 Debian package, and so there is only one "debianisation"
2940 of it and therefore no revision indication is required.
2944 It is conventional to restart the
2945 <var>debian_revision</var> at <tt>1</tt> each time the
2946 <var>upstream_version</var> is increased.
2950 The package management system will break the version
2951 number apart at the last hyphen in the string (if there
2952 is one) to determine the <var>upstream_version</var> and
2953 <var>debian_revision</var>. The absence of a
2954 <var>debian_revision</var> is equivalent to a
2955 <var>debian_revision</var> of <tt>0</tt>.
2962 When comparing two version numbers, first the <var>epoch</var>
2963 of each are compared, then the <var>upstream_version</var> if
2964 <var>epoch</var> is equal, and then <var>debian_revision</var>
2965 if <var>upstream_version</var> is also equal.
2966 <var>epoch</var> is compared numerically. The
2967 <var>upstream_version</var> and <var>debian_revision</var>
2968 parts are compared by the package management system using the
2969 following algorithm:
2973 The strings are compared from left to right.
2977 First the initial part of each string consisting entirely of
2978 non-digit characters is determined. These two parts (one of
2979 which may be empty) are compared lexically. If a difference
2980 is found it is returned. The lexical comparison is a
2981 comparison of ASCII values modified so that all the letters
2982 sort earlier than all the non-letters and so that a tilde
2983 sorts before anything, even the end of a part. For example,
2984 the following parts are in sorted order from earliest to
2985 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
2986 <tt>a</tt>.<footnote>
2987 One common use of <tt>~</tt> is for upstream pre-releases.
2988 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
2989 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
2994 Then the initial part of the remainder of each string which
2995 consists entirely of digit characters is determined. The
2996 numerical values of these two parts are compared, and any
2997 difference found is returned as the result of the comparison.
2998 For these purposes an empty string (which can only occur at
2999 the end of one or both version strings being compared) counts
3004 These two steps (comparing and removing initial non-digit
3005 strings and initial digit strings) are repeated until a
3006 difference is found or both strings are exhausted.
3010 Note that the purpose of epochs is to allow us to leave behind
3011 mistakes in version numbering, and to cope with situations
3012 where the version numbering scheme changes. It is
3013 <em>not</em> intended to cope with version numbers containing
3014 strings of letters which the package management system cannot
3015 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3016 silly orderings (the author of this manual has heard of a
3017 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3018 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3019 <tt>2</tt> and so forth).
3023 <sect1 id="f-Description">
3024 <heading><tt>Description</tt></heading>
3027 In a source or binary control file, the <tt>Description</tt>
3028 field contains a description of the binary package, consisting
3029 of two parts, the synopsis or the short description, and the
3030 long description. The field's format is as follows:
3035 Description: <single line synopsis>
3036 <extended description over several lines>
3041 The lines in the extended description can have these formats:
3047 Those starting with a single space are part of a paragraph.
3048 Successive lines of this form will be word-wrapped when
3049 displayed. The leading space will usually be stripped off.
3053 Those starting with two or more spaces. These will be
3054 displayed verbatim. If the display cannot be panned
3055 horizontally, the displaying program will line wrap them "hard"
3056 (i.e., without taking account of word breaks). If it can they
3057 will be allowed to trail off to the right. None, one or two
3058 initial spaces may be deleted, but the number of spaces
3059 deleted from each line will be the same (so that you can have
3060 indenting work correctly, for example).
3064 Those containing a single space followed by a single full stop
3065 character. These are rendered as blank lines. This is the
3066 <em>only</em> way to get a blank line<footnote>
3067 Completely empty lines will not be rendered as blank lines.
3068 Instead, they will cause the parser to think you're starting
3069 a whole new record in the control file, and will therefore
3070 likely abort with an error.
3075 Those containing a space, a full stop and some more characters.
3076 These are for future expansion. Do not use them.
3082 Do not use tab characters. Their effect is not predictable.
3086 See <ref id="descriptions"> for further information on this.
3090 In a <file>.changes</file> file, the <tt>Description</tt> field
3091 contains a summary of the descriptions for the packages being
3096 The part of the field before the first newline is empty;
3097 thereafter each line has the name of a binary package and
3098 the summary description line from that binary package.
3099 Each line is indented by one space.
3104 <sect1 id="f-Distribution">
3105 <heading><tt>Distribution</tt></heading>
3108 In a <file>.changes</file> file or parsed changelog output
3109 this contains the (space-separated) name(s) of the
3110 distribution(s) where this version of the package should
3111 be installed. Valid distributions are determined by the
3112 archive maintainers.<footnote>
3113 Current distribution names are:
3114 <taglist compact="compact">
3115 <tag><em>stable</em></tag>
3117 This is the current "released" version of Debian
3118 GNU/Linux. Once the distribution is
3119 <em>stable</em> only security fixes and other
3120 major bug fixes are allowed. When changes are
3121 made to this distribution, the release number is
3122 increased (for example: 2.2r1 becomes 2.2r2 then
3126 <tag><em>unstable</em></tag>
3128 This distribution value refers to the
3129 <em>developmental</em> part of the Debian
3130 distribution tree. New packages, new upstream
3131 versions of packages and bug fixes go into the
3132 <em>unstable</em> directory tree. Download from
3133 this distribution at your own risk.
3136 <tag><em>testing</em></tag>
3138 This distribution value refers to the
3139 <em>testing</em> part of the Debian distribution
3140 tree. It receives its packages from the
3141 unstable distribution after a short time lag to
3142 ensure that there are no major issues with the
3143 unstable packages. It is less prone to breakage
3144 than unstable, but still risky. It is not
3145 possible to upload packages directly to
3149 <tag><em>frozen</em></tag>
3151 From time to time, the <em>testing</em>
3152 distribution enters a state of "code-freeze" in
3153 anticipation of release as a <em>stable</em>
3154 version. During this period of testing only
3155 fixes for existing or newly-discovered bugs will
3156 be allowed. The exact details of this stage are
3157 determined by the Release Manager.
3160 <tag><em>experimental</em></tag>
3162 The packages with this distribution value are
3163 deemed by their maintainers to be high
3164 risk. Oftentimes they represent early beta or
3165 developmental packages from various sources that
3166 the maintainers want people to try, but are not
3167 ready to be a part of the other parts of the
3168 Debian distribution tree. Download at your own
3174 You should list <em>all</em> distributions that the
3175 package should be installed into.
3179 More information is available in the Debian Developer's
3180 Reference, section "The Debian archive".
3187 <heading><tt>Date</tt></heading>
3190 This field includes the date the package was built or last edited.
3194 The value of this field is usually extracted from the
3195 <file>debian/changelog</file> file - see
3196 <ref id="dpkgchangelog">).
3200 <sect1 id="f-Format">
3201 <heading><tt>Format</tt></heading>
3204 This field specifies a format revision for the file.
3205 The most current format described in the Policy Manual
3206 is version <strong>1.5</strong>. The syntax of the
3207 format value is the same as that of a package version
3208 number except that no epoch or Debian revision is allowed
3209 - see <ref id="f-Version">.
3213 <sect1 id="f-Urgency">
3214 <heading><tt>Urgency</tt></heading>
3217 This is a description of how important it is to upgrade to
3218 this version from previous ones. It consists of a single
3219 keyword taking one of the values <tt>low</tt>,
3220 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3221 <tt>critical</tt><footnote>
3222 Other urgency values are supported with configuration
3223 changes in the archive software but are not used in Debian.
3224 The urgency affects how quickly a package will be considered
3225 for inclusion into the <tt>testing</tt> distribution and
3226 gives an indication of the importance of any fixes included
3227 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3228 treated as synonymous.
3229 </footnote> (not case-sensitive) followed by an optional
3230 commentary (separated by a space) which is usually in
3231 parentheses. For example:
3234 Urgency: low (HIGH for users of diversions)
3240 The value of this field is usually extracted from the
3241 <file>debian/changelog</file> file - see
3242 <ref id="dpkgchangelog">.
3246 <sect1 id="f-Changes">
3247 <heading><tt>Changes</tt></heading>
3250 This field contains the human-readable changes data, describing
3251 the differences between the last version and the current one.
3255 There should be nothing in this field before the first
3256 newline; all the subsequent lines must be indented by at
3257 least one space; blank lines must be represented by a line
3258 consisting only of a space and a full stop.
3262 The value of this field is usually extracted from the
3263 <file>debian/changelog</file> file - see
3264 <ref id="dpkgchangelog">).
3268 Each version's change information should be preceded by a
3269 "title" line giving at least the version, distribution(s)
3270 and urgency, in a human-readable way.
3274 If data from several versions is being returned the entry
3275 for the most recent version should be returned first, and
3276 entries should be separated by the representation of a
3277 blank line (the "title" line may also be followed by the
3278 representation of blank line).
3282 <sect1 id="f-Binary">
3283 <heading><tt>Binary</tt></heading>
3286 This field is a list of binary packages.
3290 When it appears in the <file>.dsc</file> file it is the list
3291 of binary packages which a source package can produce. It
3292 does not necessarily produce all of these binary packages
3293 for every architecture. The source control file doesn't
3294 contain details of which architectures are appropriate for
3295 which of the binary packages.
3299 When it appears in a <file>.changes</file> file it lists the
3300 names of the binary packages actually being uploaded.
3304 The syntax is a list of binary packages separated by
3306 A space after each comma is conventional.
3307 </footnote>. Currently the packages must be separated using
3308 only spaces in the <file>.changes</file> file.
3312 <sect1 id="f-Installed-Size">
3313 <heading><tt>Installed-Size</tt></heading>
3316 This field appears in the control files of binary
3317 packages, and in the <file>Packages</file> files. It gives
3318 the total amount of disk space required to install the
3323 The disk space is represented in kilobytes as a simple
3328 <sect1 id="f-Files">
3329 <heading><tt>Files</tt></heading>
3332 This field contains a list of files with information about
3333 each one. The exact information and syntax varies with
3334 the context. In all cases the part of the field
3335 contents on the same line as the field name is empty. The
3336 remainder of the field is one line per file, each line
3337 being indented by one space and containing a number of
3338 sub-fields separated by spaces.
3342 In the <file>.dsc</file> file, each line contains the MD5
3343 checksum, size and filename of the tar file and (if applicable)
3344 diff file which make up the remainder of the source
3346 That is, the parts which are not the <tt>.dsc</tt>.
3348 The exact forms of the filenames are described
3349 in <ref id="pkg-sourcearchives">.
3353 In the <file>.changes</file> file this contains one line per
3354 file being uploaded. Each line contains the MD5 checksum,
3355 size, section and priority and the filename.
3356 The <qref id="f-Section">section</qref>
3357 and <qref id="f-Priority">priority</qref>
3358 are the values of the corresponding fields in
3359 the main source control file. If no section or priority is
3360 specified then <tt>-</tt> should be used, though section
3361 and priority values must be specified for new packages to
3362 be installed properly.
3366 The special value <tt>byhand</tt> for the section in a
3367 <tt>.changes</tt> file indicates that the file in question
3368 is not an ordinary package file and must by installed by
3369 hand by the distribution maintainers. If the section is
3370 <tt>byhand</tt> the priority should be <tt>-</tt>.
3374 If a new Debian revision of a package is being shipped and
3375 no new original source archive is being distributed the
3376 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3377 entry for the original source archive
3378 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3379 but the <file>.changes</file> file should leave it out. In
3380 this case the original source archive on the distribution
3381 site must match exactly, byte-for-byte, the original
3382 source archive which was used to generate the
3383 <file>.dsc</file> file and diff which are being uploaded.</p>
3386 <sect1 id="f-Closes">
3387 <heading><tt>Closes</tt></heading>
3390 A space-separated list of bug report numbers that the upload
3391 governed by the .changes file closes.
3395 <sect1 id="f-Homepage">
3396 <heading><tt>Homepage</tt></heading>
3399 The URL of the web site for this package, preferably (when
3400 applicable) the site from which the original source can be
3401 obtained and any additional upstream documentation or
3402 information may be found. The content of this field is a
3403 simple URL without any surrounding characters such as
3411 <heading>User-defined fields</heading>
3414 Additional user-defined fields may be added to the
3415 source package control file. Such fields will be
3416 ignored, and not copied to (for example) binary or
3417 source package control files or upload control files.
3421 If you wish to add additional unsupported fields to
3422 these output files you should use the mechanism
3427 Fields in the main source control information file with
3428 names starting <tt>X</tt>, followed by one or more of
3429 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3430 be copied to the output files. Only the part of the
3431 field name after the hyphen will be used in the output
3432 file. Where the letter <tt>B</tt> is used the field
3433 will appear in binary package control files, where the
3434 letter <tt>S</tt> is used in source package control
3435 files and where <tt>C</tt> is used in upload control
3436 (<tt>.changes</tt>) files.
3440 For example, if the main source information control file
3443 XBS-Comment: I stand between the candle and the star.
3445 then the binary and source package control files will contain the
3448 Comment: I stand between the candle and the star.
3457 <chapt id="maintainerscripts">
3458 <heading>Package maintainer scripts and installation procedure</heading>
3461 <heading>Introduction to package maintainer scripts</heading>
3464 It is possible to supply scripts as part of a package which
3465 the package management system will run for you when your
3466 package is installed, upgraded or removed.
3470 These scripts are the files <prgn>preinst</prgn>,
3471 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3472 <prgn>postrm</prgn> in the control area of the package.
3473 They must be proper executable files; if they are scripts
3474 (which is recommended), they must start with the usual
3475 <tt>#!</tt> convention. They should be readable and
3476 executable by anyone, and must not be world-writable.
3480 The package management system looks at the exit status from
3481 these scripts. It is important that they exit with a
3482 non-zero status if there is an error, so that the package
3483 management system can stop its processing. For shell
3484 scripts this means that you <em>almost always</em> need to
3485 use <tt>set -e</tt> (this is usually true when writing shell
3486 scripts, in fact). It is also important, of course, that
3487 they exit with a zero status if everything went well.
3491 Additionally, packages interacting with users using
3492 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3493 install a <prgn>config</prgn> script in the control area,
3494 see <ref id="maintscriptprompt"> for details.
3498 When a package is upgraded a combination of the scripts from
3499 the old and new packages is called during the upgrade
3500 procedure. If your scripts are going to be at all
3501 complicated you need to be aware of this, and may need to
3502 check the arguments to your scripts.
3506 Broadly speaking the <prgn>preinst</prgn> is called before
3507 (a particular version of) a package is installed, and the
3508 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3509 before (a version of) a package is removed and the
3510 <prgn>postrm</prgn> afterwards.
3514 Programs called from maintainer scripts should not normally
3515 have a path prepended to them. Before installation is
3516 started, the package management system checks to see if the
3517 programs <prgn>ldconfig</prgn>,
3518 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3519 and <prgn>update-rc.d</prgn> can be found via the
3520 <tt>PATH</tt> environment variable. Those programs, and any
3521 other program that one would expect to be in the
3522 <tt>PATH</tt>, should thus be invoked without an absolute
3523 pathname. Maintainer scripts should also not reset the
3524 <tt>PATH</tt>, though they might choose to modify it by
3525 prepending or appending package-specific directories. These
3526 considerations really apply to all shell scripts.</p>
3529 <sect id="idempotency">
3530 <heading>Maintainer scripts idempotency</heading>
3533 It is necessary for the error recovery procedures that the
3534 scripts be idempotent. This means that if it is run
3535 successfully, and then it is called again, it doesn't bomb
3536 out or cause any harm, but just ensures that everything is
3537 the way it ought to be. If the first call failed, or
3538 aborted half way through for some reason, the second call
3539 should merely do the things that were left undone the first
3540 time, if any, and exit with a success status if everything
3542 This is so that if an error occurs, the user interrupts
3543 <prgn>dpkg</prgn> or some other unforeseen circumstance
3544 happens you don't leave the user with a badly-broken
3545 package when <prgn>dpkg</prgn> attempts to repeat the
3551 <sect id="controllingterminal">
3552 <heading>Controlling terminal for maintainer scripts</heading>
3555 The maintainer scripts are guaranteed to run with a
3556 controlling terminal and can interact with the user.
3557 Because these scripts may be executed with standard output
3558 redirected into a pipe for logging purposes, Perl scripts
3559 should set unbuffered output by setting <tt>$|=1</tt> so
3560 that the output is printed immediately rather than being
3564 <sect id="exitstatus">
3565 <heading>Exit status</heading>
3568 Each script must return a zero exit status for
3569 success, or a nonzero one for failure, since the package
3570 management system looks for the exit status of these scripts
3571 and determines what action to take next based on that datum.
3575 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3580 <list compact="compact">
3582 <var>new-preinst</var> <tt>install</tt>
3585 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3588 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3591 <var>old-preinst</var> <tt>abort-upgrade</tt>
3592 <var>new-version</var>
3597 <list compact="compact">
3599 <var>postinst</var> <tt>configure</tt>
3600 <var>most-recently-configured-version</var>
3603 <var>old-postinst</var> <tt>abort-upgrade</tt>
3604 <var>new-version</var>
3607 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3608 <tt>in-favour</tt> <var>package</var>
3609 <var>new-version</var>
3612 <var>postinst</var> <tt>abort-remove</tt>
3615 <var>deconfigured's-postinst</var>
3616 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3617 <var>failed-install-package</var> <var>version</var>
3618 [<tt>removing</tt> <var>conflicting-package</var>
3624 <list compact="compact">
3626 <var>prerm</var> <tt>remove</tt>
3629 <var>old-prerm</var> <tt>upgrade</tt>
3630 <var>new-version</var>
3633 <var>new-prerm</var> <tt>failed-upgrade</tt>
3634 <var>old-version</var>
3637 <var>conflictor's-prerm</var> <tt>remove</tt>
3638 <tt>in-favour</tt> <var>package</var>
3639 <var>new-version</var>
3642 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3643 <tt>in-favour</tt> <var>package-being-installed</var>
3644 <var>version</var> [<tt>removing</tt>
3645 <var>conflicting-package</var>
3651 <list compact="compact">
3653 <var>postrm</var> <tt>remove</tt>
3656 <var>postrm</var> <tt>purge</tt>
3659 <var>old-postrm</var> <tt>upgrade</tt>
3660 <var>new-version</var>
3663 <var>new-postrm</var> <tt>failed-upgrade</tt>
3664 <var>old-version</var>
3667 <var>new-postrm</var> <tt>abort-install</tt>
3670 <var>new-postrm</var> <tt>abort-install</tt>
3671 <var>old-version</var>
3674 <var>new-postrm</var> <tt>abort-upgrade</tt>
3675 <var>old-version</var>
3678 <var>disappearer's-postrm</var> <tt>disappear</tt>
3679 <var>overwriter</var>
3680 <var>overwriter-version</var>
3686 <sect id="unpackphase">
3687 <heading>Details of unpack phase of installation or upgrade</heading>
3690 The procedure on installation/upgrade/overwrite/disappear
3691 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3692 stage of <tt>dpkg --install</tt>) is as follows. In each
3693 case, if a major error occurs (unless listed below) the
3694 actions are, in general, run backwards - this means that the
3695 maintainer scripts are run with different arguments in
3696 reverse order. These are the "error unwind" calls listed
3703 If a version of the package is already installed, call
3704 <example compact="compact">
3705 <var>old-prerm</var> upgrade <var>new-version</var>
3709 If the script runs but exits with a non-zero
3710 exit status, <prgn>dpkg</prgn> will attempt:
3711 <example compact="compact">
3712 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3714 If this works, the upgrade continues. If this
3715 does not work, the error unwind:
3716 <example compact="compact">
3717 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3719 If this works, then the old-version is
3720 "Installed", if not, the old version is in a
3721 "Failed-Config" state.
3727 If a "conflicting" package is being removed at the same time,
3728 or if any package will be broken (due to <tt>Breaks</tt>):
3731 If <tt>--auto-deconfigure</tt> is
3732 specified, call, for each package to be deconfigured
3733 due to <tt>Breaks</tt>:
3734 <example compact="compact">
3735 <var>deconfigured's-prerm</var> deconfigure \
3736 in-favour <var>package-being-installed</var> <var>version</var>
3739 <example compact="compact">
3740 <var>deconfigured's-postinst</var> abort-deconfigure \
3741 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3743 The deconfigured packages are marked as
3744 requiring configuration, so that if
3745 <tt>--install</tt> is used they will be
3746 configured again if possible.
3749 If any packages depended on a conflicting
3750 package being removed and <tt>--auto-deconfigure</tt> is
3751 specified, call, for each such package:
3752 <example compact="compact">
3753 <var>deconfigured's-prerm</var> deconfigure \
3754 in-favour <var>package-being-installed</var> <var>version</var> \
3755 removing <var>conflicting-package</var> <var>version</var>
3758 <example compact="compact">
3759 <var>deconfigured's-postinst</var> abort-deconfigure \
3760 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3761 removing <var>conflicting-package</var> <var>version</var>
3763 The deconfigured packages are marked as
3764 requiring configuration, so that if
3765 <tt>--install</tt> is used they will be
3766 configured again if possible.
3769 To prepare for removal of each conflicting package, call:
3770 <example compact="compact">
3771 <var>conflictor's-prerm</var> remove \
3772 in-favour <var>package</var> <var>new-version</var>
3775 <example compact="compact">
3776 <var>conflictor's-postinst</var> abort-remove \
3777 in-favour <var>package</var> <var>new-version</var>
3786 If the package is being upgraded, call:
3787 <example compact="compact">
3788 <var>new-preinst</var> upgrade <var>old-version</var>
3790 If this fails, we call:
3792 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3799 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3801 is called. If this works, then the old version
3802 is in an "Installed" state, or else it is left
3803 in an "Unpacked" state.
3808 If it fails, then the old version is left
3809 in an "Half-Installed" state.
3816 Otherwise, if the package had some configuration
3817 files from a previous version installed (i.e., it
3818 is in the "configuration files only" state):
3819 <example compact="compact">
3820 <var>new-preinst</var> install <var>old-version</var>
3824 <var>new-postrm</var> abort-install <var>old-version</var>
3826 If this fails, the package is left in a
3827 "Half-Installed" state, which requires a
3828 reinstall. If it works, the packages is left in
3829 a "Config Files" state.
3832 Otherwise (i.e., the package was completely purged):
3833 <example compact="compact">
3834 <var>new-preinst</var> install
3837 <example compact="compact">
3838 <var>new-postrm</var> abort-install
3840 If the error-unwind fails, the package is in a
3841 "Half Installed" phase, and requires a
3842 reinstall. If the error unwind works, the
3843 package is in a not installed state.
3850 The new package's files are unpacked, overwriting any
3851 that may be on the system already, for example any
3852 from the old version of the same package or from
3853 another package. Backups of the old files are kept
3854 temporarily, and if anything goes wrong the package
3855 management system will attempt to put them back as
3856 part of the error unwind.
3860 It is an error for a package to contain files which
3861 are on the system in another package, unless
3862 <tt>Replaces</tt> is used (see <ref id="replaces">).
3864 The following paragraph is not currently the case:
3865 Currently the <tt>- - force-overwrite</tt> flag is
3866 enabled, downgrading it to a warning, but this may not
3872 It is a more serious error for a package to contain a
3873 plain file or other kind of non-directory where another
3874 package has a directory (again, unless
3875 <tt>Replaces</tt> is used). This error can be
3876 overridden if desired using
3877 <tt>--force-overwrite-dir</tt>, but this is not
3882 Packages which overwrite each other's files produce
3883 behavior which, though deterministic, is hard for the
3884 system administrator to understand. It can easily
3885 lead to "missing" programs if, for example, a package
3886 is installed which overwrites a file from another
3887 package, and is then removed again.<footnote>
3888 Part of the problem is due to what is arguably a
3889 bug in <prgn>dpkg</prgn>.
3894 A directory will never be replaced by a symbolic link
3895 to a directory or vice versa; instead, the existing
3896 state (symlink or not) will be left alone and
3897 <prgn>dpkg</prgn> will follow the symlink if there is
3906 If the package is being upgraded, call
3907 <example compact="compact">
3908 <var>old-postrm</var> upgrade <var>new-version</var>
3912 If this fails, <prgn>dpkg</prgn> will attempt:
3913 <example compact="compact">
3914 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3916 If this works, installation continues. If not,
3918 <example compact="compact">
3919 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3921 If this fails, the old version is left in an
3922 "Half Installed" state. If it works, dpkg now
3924 <example compact="compact">
3925 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3927 If this fails, the old version is left in an
3928 "Half Installed" state. If it works, dpkg now
3930 <example compact="compact">
3931 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3933 If this fails, the old version is in an
3940 This is the point of no return - if
3941 <prgn>dpkg</prgn> gets this far, it won't back off
3942 past this point if an error occurs. This will
3943 leave the package in a fairly bad state, which
3944 will require a successful re-installation to clear
3945 up, but it's when <prgn>dpkg</prgn> starts doing
3946 things that are irreversible.
3951 Any files which were in the old version of the package
3952 but not in the new are removed.
3956 The new file list replaces the old.
3960 The new maintainer scripts replace the old.
3964 Any packages all of whose files have been overwritten
3965 during the installation, and which aren't required for
3966 dependencies, are considered to have been removed.
3967 For each such package
3970 <prgn>dpkg</prgn> calls:
3971 <example compact="compact">
3972 <var>disappearer's-postrm</var> disappear \
3973 <var>overwriter</var> <var>overwriter-version</var>
3977 The package's maintainer scripts are removed.
3980 It is noted in the status database as being in a
3981 sane state, namely not installed (any conffiles
3982 it may have are ignored, rather than being
3983 removed by <prgn>dpkg</prgn>). Note that
3984 disappearing packages do not have their prerm
3985 called, because <prgn>dpkg</prgn> doesn't know
3986 in advance that the package is going to
3993 Any files in the package we're unpacking that are also
3994 listed in the file lists of other packages are removed
3995 from those lists. (This will lobotomize the file list
3996 of the "conflicting" package if there is one.)
4000 The backup files made during installation, above, are
4006 The new package's status is now sane, and recorded as
4011 Here is another point of no return - if the
4012 conflicting package's removal fails we do not unwind
4013 the rest of the installation; the conflicting package
4014 is left in a half-removed limbo.
4019 If there was a conflicting package we go and do the
4020 removal actions (described below), starting with the
4021 removal of the conflicting package's files (any that
4022 are also in the package being installed have already
4023 been removed from the conflicting package's file list,
4024 and so do not get removed now).
4030 <sect id="configdetails"><heading>Details of configuration</heading>
4033 When we configure a package (this happens with <tt>dpkg
4034 --install</tt> and <tt>dpkg --configure</tt>), we first
4035 update any <tt>conffile</tt>s and then call:
4036 <example compact="compact">
4037 <var>postinst</var> configure <var>most-recently-configured-version</var>
4042 No attempt is made to unwind after errors during
4043 configuration. If the configuration fails, the package is in
4044 a "Failed Config" state, and an error message is generated.
4048 If there is no most recently configured version
4049 <prgn>dpkg</prgn> will pass a null argument.
4052 Historical note: Truly ancient (pre-1997) versions of
4053 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4054 (including the angle brackets) in this case. Even older
4055 ones did not pass a second argument at all, under any
4056 circumstance. Note that upgrades using such an old dpkg
4057 version are unlikely to work for other reasons, even if
4058 this old argument behavior is handled by your postinst script.
4064 <sect id="removedetails"><heading>Details of removal and/or
4065 configuration purging</heading>
4071 <example compact="compact">
4072 <var>prerm</var> remove
4076 If prerm fails during replacement due to conflict
4078 <var>conflictor's-postinst</var> abort-remove \
4079 in-favour <var>package</var> <var>new-version</var>
4083 <var>postinst</var> abort-remove
4087 If this fails, the package is in a "Failed-Config"
4088 state, or else it remains "Installed".
4092 The package's files are removed (except <tt>conffile</tt>s).
4095 <example compact="compact">
4096 <var>postrm</var> remove
4100 If it fails, there's no error unwind, and the package is in
4101 an "Half-Installed" state.
4106 All the maintainer scripts except the <prgn>postrm</prgn>
4111 If we aren't purging the package we stop here. Note
4112 that packages which have no <prgn>postrm</prgn> and no
4113 <tt>conffile</tt>s are automatically purged when
4114 removed, as there is no difference except for the
4115 <prgn>dpkg</prgn> status.
4119 The <tt>conffile</tt>s and any backup files
4120 (<tt>~</tt>-files, <tt>#*#</tt> files,
4121 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4126 <example compact="compact">
4127 <var>postrm</var> purge
4131 If this fails, the package remains in a "Config-Files"
4136 The package's file list is removed.
4145 <chapt id="relationships">
4146 <heading>Declaring relationships between packages</heading>
4148 <sect id="depsyntax">
4149 <heading>Syntax of relationship fields</heading>
4152 These fields all have a uniform syntax. They are a list of
4153 package names separated by commas.
4157 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4158 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4159 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4160 control file fields of the package, which declare
4161 dependencies on other packages, the package names listed may
4162 also include lists of alternative package names, separated
4163 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4164 if any one of the alternative packages is installed, that
4165 part of the dependency is considered to be satisfied.
4169 All of the fields except for <tt>Provides</tt> may restrict
4170 their applicability to particular versions of each named
4171 package. This is done in parentheses after each individual
4172 package name; the parentheses should contain a relation from
4173 the list below followed by a version number, in the format
4174 described in <ref id="f-Version">.
4178 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4179 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4180 strictly earlier, earlier or equal, exactly equal, later or
4181 equal and strictly later, respectively. The deprecated
4182 forms <tt><</tt> and <tt>></tt> were used to mean
4183 earlier/later or equal, rather than strictly earlier/later,
4184 so they should not appear in new packages (though
4185 <prgn>dpkg</prgn> still supports them).
4189 Whitespace may appear at any point in the version
4190 specification subject to the rules in <ref
4191 id="controlsyntax">, and must appear where it's necessary to
4192 disambiguate; it is not otherwise significant. All of the
4193 relationship fields may span multiple lines. For
4194 consistency and in case of future changes to
4195 <prgn>dpkg</prgn> it is recommended that a single space be
4196 used after a version relationship and before a version
4197 number; it is also conventional to put a single space after
4198 each comma, on either side of each vertical bar, and before
4199 each open parenthesis. When wrapping a relationship field, it
4200 is conventional to do so after a comma and before the space
4201 following that comma.
4205 For example, a list of dependencies might appear as:
4206 <example compact="compact">
4209 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4214 All fields that specify build-time relationships
4215 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4216 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4217 may be restricted to a certain set of architectures. This
4218 is indicated in brackets after each individual package name and
4219 the optional version specification. The brackets enclose a
4220 list of Debian architecture names separated by whitespace.
4221 Exclamation marks may be prepended to each of the names.
4222 (It is not permitted for some names to be prepended with
4223 exclamation marks while others aren't.) If the current Debian
4224 host architecture is not in this list and there are no
4225 exclamation marks in the list, or it is in the list with a
4226 prepended exclamation mark, the package name and the
4227 associated version specification are ignored completely for
4228 the purposes of defining the relationships.
4233 <example compact="compact">
4235 Build-Depends-Indep: texinfo
4236 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4237 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4239 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4240 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4241 <tt>gnumach-dev</tt> only on hurd-i386.
4245 If the architecture-restricted dependency is part of a set of
4246 alternatives using <tt>|</tt>, that alternative is ignored
4247 completely on architectures that do not match the restriction.
4249 <example compact="compact">
4250 Build-Depends: foo [!i386] | bar [!amd64]
4252 is equivalent to <tt>bar</tt> on the i386 architecture, to
4253 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4254 bar</tt> on all other architectures.
4258 Note that the binary package relationship fields such as
4259 <tt>Depends</tt> appear in one of the binary package
4260 sections of the control file, whereas the build-time
4261 relationships such as <tt>Build-Depends</tt> appear in the
4262 source package section of the control file (which is the
4267 <sect id="binarydeps">
4268 <heading>Binary Dependencies - <tt>Depends</tt>,
4269 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4270 <tt>Pre-Depends</tt>
4274 Packages can declare in their control file that they have
4275 certain relationships to other packages - for example, that
4276 they may not be installed at the same time as certain other
4277 packages, and/or that they depend on the presence of others.
4281 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4282 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4283 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4287 These seven fields are used to declare a dependency
4288 relationship by one package on another. Except for
4289 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4290 depending (binary) package's control file.
4291 (<tt>Enhances</tt> appears in the recommending package's
4292 control file, and <tt>Breaks</tt> appears in the version of
4293 depended-on package which causes the named package to
4298 A <tt>Depends</tt> field takes effect <em>only</em> when a
4299 package is to be configured. It does not prevent a package
4300 being on the system in an unconfigured state while its
4301 dependencies are unsatisfied, and it is possible to replace
4302 a package whose dependencies are satisfied and which is
4303 properly installed with a different version whose
4304 dependencies are not and cannot be satisfied; when this is
4305 done the depending package will be left unconfigured (since
4306 attempts to configure it will give errors) and will not
4307 function properly. If it is necessary, a
4308 <tt>Pre-Depends</tt> field can be used, which has a partial
4309 effect even when a package is being unpacked, as explained
4310 in detail below. (The other three dependency fields,
4311 <tt>Recommends</tt>, <tt>Suggests</tt> and
4312 <tt>Enhances</tt>, are only used by the various front-ends
4313 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4314 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4318 For this reason packages in an installation run are usually
4319 all unpacked first and all configured later; this gives
4320 later versions of packages with dependencies on later
4321 versions of other packages the opportunity to have their
4322 dependencies satisfied.
4326 In case of circular dependencies, since installation or
4327 removal order honoring the dependency order can't be
4328 established, dependency loops are broken at some point
4329 (based on rules below), and some packages may not be able to
4330 rely on their dependencies being present when being
4331 installed or removed, depending on which side of the break
4332 of the circular dependency loop they happen to be on. If one
4333 of the packages in the loop has no postinst script, then the
4334 cycle will be broken at that package, so as to ensure that
4335 all postinst scripts run with the dependencies properly
4336 configured if this is possible. Otherwise the breaking point
4341 The <tt>Depends</tt> field thus allows package maintainers
4342 to impose an order in which packages should be configured.
4346 The meaning of the five dependency fields is as follows:
4348 <tag><tt>Depends</tt></tag>
4351 This declares an absolute dependency. A package will
4352 not be configured unless all of the packages listed in
4353 its <tt>Depends</tt> field have been correctly
4358 The <tt>Depends</tt> field should be used if the
4359 depended-on package is required for the depending
4360 package to provide a significant amount of
4365 The <tt>Depends</tt> field should also be used if the
4366 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4367 <prgn>postrm</prgn> scripts require the package to be
4368 present in order to run. Note, however, that the
4369 <prgn>postrm</prgn> cannot rely on any non-essential
4370 packages to be present during the <tt>purge</tt>
4374 <tag><tt>Recommends</tt></tag>
4377 This declares a strong, but not absolute, dependency.
4381 The <tt>Recommends</tt> field should list packages
4382 that would be found together with this one in all but
4383 unusual installations.
4387 <tag><tt>Suggests</tt></tag>
4389 This is used to declare that one package may be more
4390 useful with one or more others. Using this field
4391 tells the packaging system and the user that the
4392 listed packages are related to this one and can
4393 perhaps enhance its usefulness, but that installing
4394 this one without them is perfectly reasonable.
4397 <tag><tt>Enhances</tt></tag>
4399 This field is similar to Suggests but works in the
4400 opposite direction. It is used to declare that a
4401 package can enhance the functionality of another
4405 <tag><tt>Pre-Depends</tt></tag>
4408 This field is like <tt>Depends</tt>, except that it
4409 also forces <prgn>dpkg</prgn> to complete installation
4410 of the packages named before even starting the
4411 installation of the package which declares the
4412 pre-dependency, as follows:
4416 When a package declaring a pre-dependency is about to
4417 be <em>unpacked</em> the pre-dependency can be
4418 satisfied if the depended-on package is either fully
4419 configured, <em>or even if</em> the depended-on
4420 package(s) are only unpacked or half-configured,
4421 provided that they have been configured correctly at
4422 some point in the past (and not removed or partially
4423 removed since). In this case, both the
4424 previously-configured and currently unpacked or
4425 half-configured versions must satisfy any version
4426 clause in the <tt>Pre-Depends</tt> field.
4430 When the package declaring a pre-dependency is about
4431 to be <em>configured</em>, the pre-dependency will be
4432 treated as a normal <tt>Depends</tt>, that is, it will
4433 be considered satisfied only if the depended-on
4434 package has been correctly configured.
4438 <tt>Pre-Depends</tt> should be used sparingly,
4439 preferably only by packages whose premature upgrade or
4440 installation would hamper the ability of the system to
4441 continue with any upgrade that might be in progress.
4445 <tt>Pre-Depends</tt> are also required if the
4446 <prgn>preinst</prgn> script depends on the named
4447 package. It is best to avoid this situation if
4455 When selecting which level of dependency to use you should
4456 consider how important the depended-on package is to the
4457 functionality of the one declaring the dependency. Some
4458 packages are composed of components of varying degrees of
4459 importance. Such a package should list using
4460 <tt>Depends</tt> the package(s) which are required by the
4461 more important components. The other components'
4462 requirements may be mentioned as Suggestions or
4463 Recommendations, as appropriate to the components' relative
4469 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4472 Using <tt>Breaks</tt> may cause problems for upgrades from older
4473 versions of Debian and should not be used until the stable
4474 release of Debian supports <tt>Breaks</tt>.
4478 When one binary package declares that it breaks another,
4479 <prgn>dpkg</prgn> will refuse to allow the package which
4480 declares <tt>Breaks</tt> be installed unless the broken
4481 package is deconfigured first, and it will refuse to
4482 allow the broken package to be reconfigured.
4486 A package will not be regarded as causing breakage merely
4487 because its configuration files are still installed; it must
4488 be at least half-installed.
4492 A special exception is made for packages which declare that
4493 they break their own package name or a virtual package which
4494 they provide (see below): this does not count as a real
4499 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4500 version clause; such a <tt>Breaks</tt> is introduced in the
4501 version of an (implicit or explicit) dependency which
4502 violates an assumption or reveals a bug in earlier versions
4503 of the broken package. This use of <tt>Breaks</tt> will
4504 inform higher-level package management tools that broken
4505 package must be upgraded before the new one.
4509 If the breaking package also overwrites some files from the
4510 older package, it should use <tt>Replaces</tt> (not
4511 <tt>Conflicts</tt>) to ensure this goes smoothly.
4515 <sect id="conflicts">
4516 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4519 When one binary package declares a conflict with another
4520 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4521 refuse to allow them to be installed on the system at the
4526 If one package is to be installed, the other must be removed
4527 first - if the package being installed is marked as
4528 replacing (see <ref id="replaces">) the one on the system,
4529 or the one on the system is marked as deselected, or both
4530 packages are marked <tt>Essential</tt>, then
4531 <prgn>dpkg</prgn> will automatically remove the package
4532 which is causing the conflict, otherwise it will halt the
4533 installation of the new package with an error. This
4534 mechanism is specifically designed to produce an error when
4535 the installed package is <tt>Essential</tt>, but the new
4540 A package will not cause a conflict merely because its
4541 configuration files are still installed; it must be at least
4546 A special exception is made for packages which declare a
4547 conflict with their own package name, or with a virtual
4548 package which they provide (see below): this does not
4549 prevent their installation, and allows a package to conflict
4550 with others providing a replacement for it. You use this
4551 feature when you want the package in question to be the only
4552 package providing some feature.
4556 A <tt>Conflicts</tt> entry should almost never have an
4557 "earlier than" version clause. This would prevent
4558 <prgn>dpkg</prgn> from upgrading or installing the package
4559 which declared such a conflict until the upgrade or removal
4560 of the conflicted-with package had been completed. Instead,
4561 <tt>Breaks</tt> may be used (once <tt>Breaks</tt> is supported
4562 by the stable release of Debian).
4566 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4570 As well as the names of actual ("concrete") packages, the
4571 package relationship fields <tt>Depends</tt>,
4572 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4573 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4574 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4575 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4576 may mention "virtual packages".
4580 A <em>virtual package</em> is one which appears in the
4581 <tt>Provides</tt> control file field of another package.
4582 The effect is as if the package(s) which provide a
4583 particular virtual package name had been listed by name
4584 everywhere the virtual package name appears. (See also <ref
4589 If there are both concrete and virtual packages of the same
4590 name, then the dependency may be satisfied (or the conflict
4591 caused) by either the concrete package with the name in
4592 question or any other concrete package which provides the
4593 virtual package with the name in question. This is so that,
4594 for example, supposing we have
4595 <example compact="compact">
4598 </example> and someone else releases an enhanced version of
4599 the <tt>bar</tt> package they can say:
4600 <example compact="compact">
4604 and the <tt>bar-plus</tt> package will now also satisfy the
4605 dependency for the <tt>foo</tt> package.
4609 If a relationship field has a version number attached
4610 then only real packages will be considered to see whether
4611 the relationship is satisfied (or the prohibition violated,
4612 for a conflict or breakage) - it is assumed that a real
4613 package which provides the virtual package is not of the
4614 "right" version. So, a <tt>Provides</tt> field may not
4615 contain version numbers, and the version number of the
4616 concrete package which provides a particular virtual package
4617 will not be looked at when considering a dependency on or
4618 conflict with the virtual package name.
4622 It is likely that the ability will be added in a future
4623 release of <prgn>dpkg</prgn> to specify a version number for
4624 each virtual package it provides. This feature is not yet
4625 present, however, and is expected to be used only
4630 If you want to specify which of a set of real packages
4631 should be the default to satisfy a particular dependency on
4632 a virtual package, you should list the real package as an
4633 alternative before the virtual one.
4638 <sect id="replaces"><heading>Overwriting files and replacing
4639 packages - <tt>Replaces</tt></heading>
4642 Packages can declare in their control file that they should
4643 overwrite files in certain other packages, or completely
4644 replace other packages. The <tt>Replaces</tt> control file
4645 field has these two distinct purposes.
4648 <sect1><heading>Overwriting files in other packages</heading>
4651 Firstly, as mentioned before, it is usually an error for a
4652 package to contain files which are on the system in
4657 However, if the overwriting package declares that it
4658 <tt>Replaces</tt> the one containing the file being
4659 overwritten, then <prgn>dpkg</prgn> will replace the file
4660 from the old package with that from the new. The file
4661 will no longer be listed as "owned" by the old package.
4665 If a package is completely replaced in this way, so that
4666 <prgn>dpkg</prgn> does not know of any files it still
4667 contains, it is considered to have "disappeared". It will
4668 be marked as not wanted on the system (selected for
4669 removal) and not installed. Any <tt>conffile</tt>s
4670 details noted for the package will be ignored, as they
4671 will have been taken over by the overwriting package. The
4672 package's <prgn>postrm</prgn> script will be run with a
4673 special argument to allow the package to do any final
4674 cleanup required. See <ref id="mscriptsinstact">.
4677 Replaces is a one way relationship -- you have to
4678 install the replacing package after the replaced
4685 For this usage of <tt>Replaces</tt>, virtual packages (see
4686 <ref id="virtual">) are not considered when looking at a
4687 <tt>Replaces</tt> field - the packages declared as being
4688 replaced must be mentioned by their real names.
4692 Furthermore, this usage of <tt>Replaces</tt> only takes
4693 effect when both packages are at least partially on the
4694 system at once, so that it can only happen if they do not
4695 conflict or if the conflict has been overridden.
4700 <sect1><heading>Replacing whole packages, forcing their
4704 Secondly, <tt>Replaces</tt> allows the packaging system to
4705 resolve which package should be removed when there is a
4706 conflict - see <ref id="conflicts">. This usage only
4707 takes effect when the two packages <em>do</em> conflict,
4708 so that the two usages of this field do not interfere with
4713 In this situation, the package declared as being replaced
4714 can be a virtual package, so for example, all mail
4715 transport agents (MTAs) would have the following fields in
4716 their control files:
4717 <example compact="compact">
4718 Provides: mail-transport-agent
4719 Conflicts: mail-transport-agent
4720 Replaces: mail-transport-agent
4722 ensuring that only one MTA can be installed at any one
4727 <sect id="sourcebinarydeps">
4728 <heading>Relationships between source and binary packages -
4729 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4730 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4734 Source packages that require certain binary packages to be
4735 installed or absent at the time of building the package
4736 can declare relationships to those binary packages.
4740 This is done using the <tt>Build-Depends</tt>,
4741 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4742 <tt>Build-Conflicts-Indep</tt> control file fields.
4746 Build-dependencies on "build-essential" binary packages can be
4747 omitted. Please see <ref id="pkg-relations"> for more information.
4751 The dependencies and conflicts they define must be satisfied
4752 (as defined earlier for binary packages) in order to invoke
4753 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4755 If you make "build-arch" or "binary-arch", you need
4756 Build-Depends. If you make "build-indep" or
4757 "binary-indep", you need Build-Depends and
4758 Build-Depends-Indep. If you make "build" or "binary",
4762 There is no Build-Depends-Arch; this role is essentially
4763 met with Build-Depends. Anyone building the
4764 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4765 is basically assumed to be building the whole package
4766 anyway and so installs all build dependencies. The
4767 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4768 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4769 does not yet know how to check for its existence) and
4770 <tt>binary-arch</tt>.
4773 The purpose of the original split, I recall, was so that
4774 the autobuilders wouldn't need to install extra packages
4775 needed only for the binary-indep targets. But without a
4776 build-arch/build-indep split, this didn't work, since
4777 most of the work is done in the build target, not in the
4783 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4785 The <tt>Build-Depends</tt> and
4786 <tt>Build-Conflicts</tt> fields must be satisfied when
4787 any of the following targets is invoked:
4788 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4789 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4790 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4792 <tag><tt>Build-Depends-Indep</tt>,
4793 <tt>Build-Conflicts-Indep</tt></tag>
4795 The <tt>Build-Depends-Indep</tt> and
4796 <tt>Build-Conflicts-Indep</tt> fields must be
4797 satisfied when any of the following targets is
4798 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4799 <tt>binary</tt> and <tt>binary-indep</tt>.
4809 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4812 Packages containing shared libraries must be constructed with
4813 a little care to make sure that the shared library is always
4814 available. This is especially important for packages whose
4815 shared libraries are vitally important, such as the C library
4816 (currently <tt>libc6</tt>).
4820 Packages involving shared libraries should be split up into
4821 several binary packages. This section mostly deals with how
4822 this separation is to be accomplished; rules for files within
4823 the shared library packages are in <ref id="libraries"> instead.
4826 <sect id="sharedlibs-runtime">
4827 <heading>Run-time shared libraries</heading>
4830 The run-time shared library needs to be placed in a package
4831 whose name changes whenever the shared object version
4834 Since it is common place to install several versions of a
4835 package that just provides shared libraries, it is a
4836 good idea that the library package should not
4837 contain any extraneous non-versioned files, unless they
4838 happen to be in versioned directories.</p>
4840 The most common mechanism is to place it in a package
4842 <package><var>libraryname</var><var>soversion</var></package>,
4843 where <file><var>soversion</var></file> is the version number
4844 in the soname of the shared library<footnote>
4845 The soname is the shared object name: it's the thing
4846 that has to match exactly between building an executable
4847 and running it for the dynamic linker to be able run the
4848 program. For example, if the soname of the library is
4849 <file>libfoo.so.6</file>, the library package would be
4850 called <file>libfoo6</file>.
4852 Alternatively, if it would be confusing to directly append
4853 <var>soversion</var> to <var>libraryname</var> (e.g. because
4854 <var>libraryname</var> itself ends in a number), you may use
4855 <package><var>libraryname</var>-<var>soversion</var></package> and
4856 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4861 If you have several shared libraries built from the same
4862 source tree you may lump them all together into a single
4863 shared library package, provided that you change all of
4864 their sonames at once (so that you don't get filename
4865 clashes if you try to install different versions of the
4866 combined shared libraries package).
4870 The package should install the shared libraries under
4871 their normal names. For example, the <package>libgdbm3</package>
4872 package should install <file>libgdbm.so.3.0.0</file> as
4873 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4874 renamed or re-linked by any <prgn>prerm</prgn> or
4875 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4876 of renaming things safely without affecting running programs,
4877 and attempts to interfere with this are likely to lead to
4882 Shared libraries should not be installed executable, since
4883 the dynamic linker does not require this and trying to
4884 execute a shared library usually results in a core dump.
4888 The run-time library package should include the symbolic link that
4889 <prgn>ldconfig</prgn> would create for the shared libraries.
4890 For example, the <package>libgdbm3</package> package should include
4891 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4892 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4893 linker (for example <prgn>ld.so</prgn> or
4894 <prgn>ld-linux.so.*</prgn>) can find the library between the
4895 time that <prgn>dpkg</prgn> installs it and the time that
4896 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4898 The package management system requires the library to be
4899 placed before the symbolic link pointing to it in the
4900 <file>.deb</file> file. This is so that when
4901 <prgn>dpkg</prgn> comes to install the symlink
4902 (overwriting the previous symlink pointing at an older
4903 version of the library), the new shared library is already
4904 in place. In the past, this was achieved by creating the
4905 library in the temporary packaging directory before
4906 creating the symlink. Unfortunately, this was not always
4907 effective, since the building of the tar file in the
4908 <file>.deb</file> depended on the behavior of the underlying
4909 file system. Some file systems (such as reiserfs) reorder
4910 the files so that the order of creation is forgotten.
4911 Since version 1.7.0, <prgn>dpkg</prgn>
4912 reorders the files itself as necessary when building a
4913 package. Thus it is no longer important to concern
4914 oneself with the order of file creation.
4918 <sect1 id="ldconfig">
4919 <heading><tt>ldconfig</tt></heading>
4922 Any package installing shared libraries in one of the default
4923 library directories of the dynamic linker (which are currently
4924 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4925 listed in <file>/etc/ld.so.conf</file><footnote>
4927 <list compact="compact">
4928 <item>/usr/local/lib</item>
4929 <item>/usr/lib/libc5-compat</item>
4930 <item>/lib/libc5-compat</item>
4933 must use <prgn>ldconfig</prgn> to update the shared library
4938 The package maintainer scripts must only call
4939 <prgn>ldconfig</prgn> under these circumstances:
4940 <list compact="compact">
4941 <item>When the <prgn>postinst</prgn> script is run with a
4942 first argument of <tt>configure</tt>, the script must call
4943 <prgn>ldconfig</prgn>, and may optionally invoke
4944 <prgn>ldconfig</prgn> at other times.
4946 <item>When the <prgn>postrm</prgn> script is run with a
4947 first argument of <tt>remove</tt>, the script should call
4948 <prgn>ldconfig</prgn>.
4953 During install or upgrade, the preinst is called before
4954 the new files are installed, so calling "ldconfig" is
4955 pointless. The preinst of an existing package can also be
4956 called if an upgrade fails. However, this happens during
4957 the critical time when a shared libs may exist on-disk
4958 under a temporary name. Thus, it is dangerous and
4959 forbidden by current policy to call "ldconfig" at this
4964 When a package is installed or upgraded, "postinst
4965 configure" runs after the new files are safely on-disk.
4966 Since it is perfectly safe to invoke ldconfig
4967 unconditionally in a postinst, it is OK for a package to
4968 simply put ldconfig in its postinst without checking the
4969 argument. The postinst can also be called to recover from
4970 a failed upgrade. This happens before any new files are
4971 unpacked, so there is no reason to call "ldconfig" at this
4976 For a package that is being removed, prerm is
4977 called with all the files intact, so calling ldconfig is
4978 useless. The other calls to "prerm" happen in the case of
4979 upgrade at a time when all the files of the old package
4980 are on-disk, so again calling "ldconfig" is pointless.
4984 postrm, on the other hand, is called with the "remove"
4985 argument just after the files are removed, so this is
4986 the proper time to call "ldconfig" to notify the system
4987 of the fact that the shared libraries from the package
4988 are removed. The postrm can be called at several other
4989 times. At the time of "postrm purge", "postrm
4990 abort-install", or "postrm abort-upgrade", calling
4991 "ldconfig" is useless because the shared lib files are
4992 not on-disk. However, when "postrm" is invoked with
4993 arguments "upgrade", "failed-upgrade", or "disappear", a
4994 shared lib may exist on-disk under a temporary filename.
5002 <sect id="sharedlibs-support-files">
5003 <heading>Shared library support files</heading>
5006 If your package contains files whose names do not change with
5007 each change in the library shared object version, you must not
5008 put them in the shared library package. Otherwise, several
5009 versions of the shared library cannot be installed at the same
5010 time without filename clashes, making upgrades and transitions
5011 unnecessarily difficult.
5015 It is recommended that supporting files and run-time support
5016 programs that do not need to be invoked manually by users, but
5017 are nevertheless required for the package to function, be placed
5018 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5019 preferably under <file>/usr/lib/</file><var>package-name</var>.
5020 If the program or file is architecture independent, the
5021 recommendation is for it to be placed in a subdirectory of
5022 <file>/usr/share</file> instead, preferably under
5023 <file>/usr/share/</file><var>package-name</var>. Following the
5024 <var>package-name</var> naming convention ensures that the file
5025 names change when the shared object version changes.
5029 Run-time support programs that use the shared library but are
5030 not required for the library to function or files used by the
5031 shared library that can be used by any version of the shared
5032 library package should instead be put in a separate package.
5033 This package might typically be named
5034 <package><var>libraryname</var>-tools</package>; note the
5035 absence of the <var>soversion</var> in the package name.
5039 Files and support programs only useful when compiling software
5040 against the library should be included in the development
5041 package for the library.<footnote>
5042 For example, a <file><var>package-name</var>-config</file>
5043 script or <package>pkg-config</package> configuration files.
5048 <sect id="sharedlibs-static">
5049 <heading>Static libraries</heading>
5052 The static library (<file><var>libraryname.a</var></file>)
5053 is usually provided in addition to the shared version.
5054 It is placed into the development package (see below).
5058 In some cases, it is acceptable for a library to be
5059 available in static form only; these cases include:
5061 <item>libraries for languages whose shared library support
5062 is immature or unstable</item>
5063 <item>libraries whose interfaces are in flux or under
5064 development (commonly the case when the library's
5065 major version number is zero, or where the ABI breaks
5066 across patchlevels)</item>
5067 <item>libraries which are explicitly intended to be
5068 available only in static form by their upstream
5073 <sect id="sharedlibs-dev">
5074 <heading>Development files</heading>
5077 The development files associated to a shared library need to be
5078 placed in a package called
5079 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5080 or if you prefer only to support one development version at a
5081 time, <package><var>libraryname</var>-dev</package>.
5085 In case several development versions of a library exist, you may
5086 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5087 <ref id="conflicts">) to ensure that the user only installs one
5088 development version at a time (as different development versions are
5089 likely to have the same header files in them, which would cause a
5090 filename clash if both were installed).
5094 The development package should contain a symlink for the associated
5095 shared library without a version number. For example, the
5096 <package>libgdbm-dev</package> package should include a symlink
5097 from <file>/usr/lib/libgdbm.so</file> to
5098 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5099 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5100 <file>libgdbm.so</file> when compiling dynamically.
5104 <sect id="sharedlibs-intradeps">
5105 <heading>Dependencies between the packages of the same library</heading>
5108 Typically the development version should have an exact
5109 version dependency on the runtime library, to make sure that
5110 compilation and linking happens correctly. The
5111 <tt>${binary:Version}</tt> substitution variable can be
5112 useful for this purpose.
5114 Previously, <tt>${Source-Version}</tt> was used, but its name
5115 was confusing and it has been deprecated since dpkg 1.13.19.
5120 <sect id="sharedlibs-shlibdeps">
5121 <heading>Dependencies between the library and other packages -
5122 the <tt>shlibs</tt> system</heading>
5125 If a package contains a binary or library which links to a
5126 shared library, we must ensure that when the package is
5127 installed on the system, all of the libraries needed are
5128 also installed. This requirement led to the creation of the
5129 <tt>shlibs</tt> system, which is very simple in its design:
5130 any package which <em>provides</em> a shared library also
5131 provides information on the package dependencies required to
5132 ensure the presence of this library, and any package which
5133 <em>uses</em> a shared library uses this information to
5134 determine the dependencies it requires. The files which
5135 contain the mapping from shared libraries to the necessary
5136 dependency information are called <file>shlibs</file> files.
5140 Thus, when a package is built which contains any shared
5141 libraries, it must provide a <file>shlibs</file> file for other
5142 packages to use, and when a package is built which contains
5143 any shared libraries or compiled binaries, it must run
5144 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5145 on these to determine the libraries used and hence the
5146 dependencies needed by this package.<footnote>
5148 In the past, the shared libraries linked to were
5149 determined by calling <prgn>ldd</prgn>, but now
5150 <prgn>objdump</prgn> is used to do this. The only
5151 change this makes to package building is that
5152 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5153 libraries, whereas in the past this was unnecessary.
5154 The rest of this footnote explains the advantage that
5159 We say that a binary <tt>foo</tt> <em>directly</em> uses
5160 a library <tt>libbar</tt> if it is explicitly linked
5161 with that library (that is, it uses the flag
5162 <tt>-lbar</tt> during the linking stage). Other
5163 libraries that are needed by <tt>libbar</tt> are linked
5164 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5165 linker will load them automatically when it loads
5166 <tt>libbar</tt>. A package should depend on
5167 the libraries it directly uses, and the dependencies for
5168 those libraries should automatically pull in the other
5173 Unfortunately, the <prgn>ldd</prgn> program shows both
5174 the directly and indirectly used libraries, meaning that
5175 the dependencies determined included both direct and
5176 indirect dependencies. The use of <prgn>objdump</prgn>
5177 avoids this problem by determining only the directly
5182 A good example of where this helps is the following. We
5183 could update <tt>libimlib</tt> with a new version that
5184 supports a new graphics format called dgf (but retaining
5185 the same major version number). If we used the old
5186 <prgn>ldd</prgn> method, every package that uses
5187 <tt>libimlib</tt> would need to be recompiled so it
5188 would also depend on <tt>libdgf</tt> or it wouldn't run
5189 due to missing symbols. However with the new system,
5190 packages using <tt>libimlib</tt> can rely on
5191 <tt>libimlib</tt> itself having the dependency on
5192 <tt>libdgf</tt> and so they would not need rebuilding.
5198 In the following sections, we will first describe where the
5199 various <tt>shlibs</tt> files are to be found, then how to
5200 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5201 file format and how to create them if your package contains a
5206 <heading>The <tt>shlibs</tt> files present on the system</heading>
5209 There are several places where <tt>shlibs</tt> files are
5210 found. The following list gives them in the order in which
5212 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5213 (The first one which gives the required information is used.)
5219 <p><file>debian/shlibs.local</file></p>
5222 This lists overrides for this package. Its use is
5223 described below (see <ref id="shlibslocal">).
5228 <p><file>/etc/dpkg/shlibs.override</file></p>
5231 This lists global overrides. This list is normally
5232 empty. It is maintained by the local system
5238 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5241 When packages are being built, any
5242 <file>debian/shlibs</file> files are copied into the
5243 control file area of the temporary build directory and
5244 given the name <file>shlibs</file>. These files give
5245 details of any shared libraries included in the
5247 An example may help here. Let us say that the
5248 source package <tt>foo</tt> generates two binary
5249 packages, <tt>libfoo2</tt> and
5250 <tt>foo-runtime</tt>. When building the binary
5251 packages, the two packages are created in the
5252 directories <file>debian/libfoo2</file> and
5253 <file>debian/foo-runtime</file> respectively.
5254 (<file>debian/tmp</file> could be used instead of one
5255 of these.) Since <tt>libfoo2</tt> provides the
5256 <tt>libfoo</tt> shared library, it will require a
5257 <tt>shlibs</tt> file, which will be installed in
5258 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5260 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5261 when <prgn>dpkg-shlibdeps</prgn> is run on the
5263 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5265 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5266 determine whether <tt>foo-prog</tt>'s library
5267 dependencies are satisfied by any of the libraries
5268 provided by <tt>libfoo2</tt>. For this reason,
5269 <prgn>dpkg-shlibdeps</prgn> must only be run once
5270 all of the individual binary packages'
5271 <tt>shlibs</tt> files have been installed into the
5278 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5281 These are the <file>shlibs</file> files corresponding to
5282 all of the packages installed on the system, and are
5283 maintained by the relevant package maintainers.
5288 <p><file>/etc/dpkg/shlibs.default</file></p>
5291 This file lists any shared libraries whose packages
5292 have failed to provide correct <file>shlibs</file> files.
5293 It was used when the <file>shlibs</file> setup was first
5294 introduced, but it is now normally empty. It is
5295 maintained by the <tt>dpkg</tt> maintainer.
5303 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5304 <file>shlibs</file> files</heading>
5308 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5309 into your <file>debian/rules</file> file. If your package
5310 contains only compiled binaries and libraries (but no scripts),
5311 you can use a command such as:
5312 <example compact="compact">
5313 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5314 debian/tmp/usr/lib/*
5316 Otherwise, you will need to explicitly list the compiled
5317 binaries and libraries.<footnote>
5318 If you are using <tt>debhelper</tt>, the
5319 <prgn>dh_shlibdeps</prgn> program will do this work for
5320 you. It will also correctly handle multi-binary
5326 This command puts the dependency information into the
5327 <file>debian/substvars</file> file, which is then used by
5328 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5329 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5330 field in the control file for this to work.
5334 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5335 done. If it does complain you might need to create your own
5336 <file>debian/shlibs.local</file> file, as explained below (see
5337 <ref id="shlibslocal">).
5341 If you have multiple binary packages, you will need to call
5342 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5343 compiled libraries or binaries. In such a case, you will
5344 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5345 utilities to specify a different <file>substvars</file> file.
5349 If you are creating a udeb for use in the Debian Installer, you
5350 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5351 the dependency line of type <tt>udeb</tt> by adding
5352 <tt>-tudeb</tt> as option<footnote>
5353 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5354 will automatically add this option if it knows it is
5356 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5357 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5358 fall back to the regular dependency line.
5362 For more details on dpkg-shlibdeps, please see
5363 <ref id="pkg-dpkg-shlibdeps"> and
5364 <manref name="dpkg-shlibdeps" section="1">.
5369 <heading>The <file>shlibs</file> File Format</heading>
5372 Each <file>shlibs</file> file has the same format. Lines
5373 beginning with <tt>#</tt> are considered to be comments and
5374 are ignored. Each line is of the form:
5375 <example compact="compact">
5376 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5381 We will explain this by reference to the example of the
5382 <tt>zlib1g</tt> package, which (at the time of writing)
5383 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5387 <var>type</var> is an optional element that indicates the type
5388 of package for which the line is valid. The only type currently
5389 in use is <tt>udeb</tt>. The colon and space after the type are
5394 <var>library-name</var> is the name of the shared library,
5395 in this case <tt>libz</tt>. (This must match the name part
5396 of the soname, see below.)
5400 <var>soname-version</var> is the version part of the soname of
5401 the library. The soname is the thing that must exactly match
5402 for the library to be recognized by the dynamic linker, and is
5404 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5405 example, <tt>libz.so.1</tt>.<footnote>
5406 This can be determined using the command
5407 <example compact="compact">
5408 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5411 The version part is the part which comes after
5412 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5416 <var>dependencies</var> has the same syntax as a dependency
5417 field in a binary package control file. It should give
5418 details of which packages are required to satisfy a binary
5419 built against the version of the library contained in the
5420 package. See <ref id="depsyntax"> for details.
5424 In our example, if the first version of the <tt>zlib1g</tt>
5425 package which contained a minor number of at least
5426 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5427 <tt>shlibs</tt> entry for this library could say:
5428 <example compact="compact">
5429 libz 1 zlib1g (>= 1:1.1.3)
5431 The version-specific dependency is to avoid warnings from
5432 the dynamic linker about using older shared libraries with
5437 As zlib1g also provides a udeb containing the shared library,
5438 there would also be a second line:
5439 <example compact="compact">
5440 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5446 <heading>Providing a <file>shlibs</file> file</heading>
5449 If your package provides a shared library, you need to create
5450 a <file>shlibs</file> file following the format described above.
5451 It is usual to call this file <file>debian/shlibs</file> (but if
5452 you have multiple binary packages, you might want to call it
5453 <file>debian/shlibs.<var>package</var></file> instead). Then
5454 let <file>debian/rules</file> install it in the control area:
5455 <example compact="compact">
5456 install -m644 debian/shlibs debian/tmp/DEBIAN
5458 or, in the case of a multi-binary package:
5459 <example compact="compact">
5460 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5462 An alternative way of doing this is to create the
5463 <file>shlibs</file> file in the control area directly from
5464 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5465 file at all,<footnote>
5466 This is what <prgn>dh_makeshlibs</prgn> in the
5467 <tt>debhelper</tt> suite does. If your package also has a udeb
5468 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5469 automatically generate the <tt>udeb:</tt> lines if you specify
5470 the name of the udeb with the <tt>--add-udeb</tt> option.
5472 since the <file>debian/shlibs</file> file itself is ignored by
5473 <prgn>dpkg-shlibdeps</prgn>.
5477 As <prgn>dpkg-shlibdeps</prgn> reads the
5478 <file>DEBIAN/shlibs</file> files in all of the binary packages
5479 being built from this source package, all of the
5480 <file>DEBIAN/shlibs</file> files should be installed before
5481 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5486 <sect1 id="shlibslocal">
5487 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5490 This file is intended only as a <em>temporary</em> fix if
5491 your binaries or libraries depend on a library whose package
5492 does not yet provide a correct <file>shlibs</file> file.
5496 We will assume that you are trying to package a binary
5497 <tt>foo</tt>. When you try running
5498 <prgn>dpkg-shlibdeps</prgn> you get the following error
5499 message (<tt>-O</tt> displays the dependency information on
5500 <tt>stdout</tt> instead of writing it to
5501 <tt>debian/substvars</tt>, and the lines have been wrapped
5502 for ease of reading):
5503 <example compact="compact">
5504 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5505 dpkg-shlibdeps: warning: unable to find dependency
5506 information for shared library libbar (soname 1,
5507 path /usr/lib/libbar.so.1, dependency field Depends)
5508 shlibs:Depends=libc6 (>= 2.2.2-2)
5510 You can then run <prgn>ldd</prgn> on the binary to find the
5511 full location of the library concerned:
5512 <example compact="compact">
5514 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5515 libc.so.6 => /lib/libc.so.6 (0x40032000)
5516 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5518 So the <prgn>foo</prgn> binary depends on the
5519 <prgn>libbar</prgn> shared library, but no package seems to
5520 provide a <file>*.shlibs</file> file handling
5521 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5522 determine the package responsible:
5523 <example compact="compact">
5524 $ dpkg -S /usr/lib/libbar.so.1
5525 bar1: /usr/lib/libbar.so.1
5526 $ dpkg -s bar1 | grep Version
5529 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5530 is the one we are using. Now we can file a bug against the
5531 <tt>bar1</tt> package and create our own
5532 <file>debian/shlibs.local</file> to locally fix the problem.
5533 Including the following line into your
5534 <file>debian/shlibs.local</file> file:
5535 <example compact="compact">
5536 libbar 1 bar1 (>= 1.0-1)
5538 should allow the package build to work.
5542 As soon as the maintainer of <tt>bar1</tt> provides a
5543 correct <file>shlibs</file> file, you should remove this line
5544 from your <file>debian/shlibs.local</file> file. (You should
5545 probably also then have a versioned <tt>Build-Depends</tt>
5546 on <tt>bar1</tt> to help ensure that others do not have the
5547 same problem building your package.)
5556 <chapt id="opersys"><heading>The Operating System</heading>
5559 <heading>File system hierarchy</heading>
5563 <heading>File System Structure</heading>
5566 The location of all installed files and directories must
5567 comply with the Filesystem Hierarchy Standard (FHS),
5568 version 2.3, with the exceptions noted below, and except
5569 where doing so would violate other terms of Debian
5570 Policy. The following exceptions to the FHS apply:
5575 The optional rules related to user specific
5576 configuration files for applications are stored in
5577 the user's home directory are relaxed. It is
5578 recommended that such files start with the
5579 '<tt>.</tt>' character (a "dot file"), and if an
5580 application needs to create more than one dot file
5581 then the preferred placement is in a subdirectory
5582 with a name starting with a '.' character, (a "dot
5583 directory"). In this case it is recommended the
5584 configuration files not start with the '.'
5590 The requirement for amd64 to use <file>/lib64</file>
5591 for 64 bit binaries is removed.
5596 The requirement that
5597 <file>/usr/local/share/man</file> be "synonymous"
5598 with <file>/usr/local/man</file> is relaxed to a
5603 The requirement that windowmanagers with a single
5604 configuration file call it <file>system.*wmrc</file>
5605 is removed, as is the restriction that the window
5606 manager subdirectory be named identically to the
5607 window manager name itself.
5612 The requirement that boot manager configuration
5613 files live in <file>/etc</file>, or at least are
5614 symlinked there, is relaxed to a recommendation.
5621 The version of this document referred here can be
5622 found in the <tt>debian-policy</tt> package or on <url
5623 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5624 name="FHS (Debian copy)"> alongside this manual (or, if
5625 you have the <package>debian-policy</package> installed,
5627 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5628 (local copy)">). The
5629 latest version, which may be a more recent version, may
5631 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5632 Specific questions about following the standard may be
5633 asked on the <tt>debian-devel</tt> mailing list, or
5634 referred to the FHS mailing list (see the
5635 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5641 <heading>Site-specific programs</heading>
5644 As mandated by the FHS, packages must not place any
5645 files in <file>/usr/local</file>, either by putting them in
5646 the file system archive to be unpacked by <prgn>dpkg</prgn>
5647 or by manipulating them in their maintainer scripts.
5651 However, the package may create empty directories below
5652 <file>/usr/local</file> so that the system administrator knows
5653 where to place site-specific files. These are not
5654 directories <em>in</em> <file>/usr/local</file>, but are
5655 children of directories in <file>/usr/local</file>. These
5656 directories (<file>/usr/local/*/dir/</file>)
5657 should be removed on package removal if they are
5662 Note, that this applies only to directories <em>below</em>
5663 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5664 Packages must not create sub-directories in the directory
5665 <file>/usr/local</file> itself, except those listed in FHS,
5666 section 4.5. However, you may create directories below
5667 them as you wish. You must not remove any of the
5668 directories listed in 4.5, even if you created them.
5672 Since <file>/usr/local</file> can be mounted read-only from a
5673 remote server, these directories must be created and
5674 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5675 maintainer scripts and not be included in the
5676 <file>.deb</file> archive. These scripts must not fail if
5677 either of these operations fail.
5681 For example, the <tt>emacsen-common</tt> package could
5682 contain something like
5683 <example compact="compact">
5684 if [ ! -e /usr/local/share/emacs ]
5686 if mkdir /usr/local/share/emacs 2>/dev/null
5688 chown root:staff /usr/local/share/emacs
5689 chmod 2775 /usr/local/share/emacs
5693 in its <prgn>postinst</prgn> script, and
5694 <example compact="compact">
5695 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5696 rmdir /usr/local/share/emacs 2>/dev/null || true
5698 in the <prgn>prerm</prgn> script. (Note that this form is
5699 used to ensure that if the script is interrupted, the
5700 directory <file>/usr/local/share/emacs</file> will still be
5705 If you do create a directory in <file>/usr/local</file> for
5706 local additions to a package, you should ensure that
5707 settings in <file>/usr/local</file> take precedence over the
5708 equivalents in <file>/usr</file>.
5712 However, because <file>/usr/local</file> and its contents are
5713 for exclusive use of the local administrator, a package
5714 must not rely on the presence or absence of files or
5715 directories in <file>/usr/local</file> for normal operation.
5719 The <file>/usr/local</file> directory itself and all the
5720 subdirectories created by the package should (by default) have
5721 permissions 2775 (group-writable and set-group-id) and be
5722 owned by <tt>root:staff</tt>.
5727 <heading>The system-wide mail directory</heading>
5729 The system-wide mail directory is <file>/var/mail</file>. This
5730 directory is part of the base system and should not owned
5731 by any particular mail agents. The use of the old
5732 location <file>/var/spool/mail</file> is deprecated, even
5733 though the spool may still be physically located there.
5739 <heading>Users and groups</heading>
5742 <heading>Introduction</heading>
5744 The Debian system can be configured to use either plain or
5749 Some user ids (UIDs) and group ids (GIDs) are reserved
5750 globally for use by certain packages. Because some
5751 packages need to include files which are owned by these
5752 users or groups, or need the ids compiled into binaries,
5753 these ids must be used on any Debian system only for the
5754 purpose for which they are allocated. This is a serious
5755 restriction, and we should avoid getting in the way of
5756 local administration policies. In particular, many sites
5757 allocate users and/or local system groups starting at 100.
5761 Apart from this we should have dynamically allocated ids,
5762 which should by default be arranged in some sensible
5763 order, but the behavior should be configurable.
5767 Packages other than <tt>base-passwd</tt> must not modify
5768 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5769 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5774 <heading>UID and GID classes</heading>
5776 The UID and GID numbers are divided into classes as
5782 Globally allocated by the Debian project, the same
5783 on every Debian system. These ids will appear in
5784 the <file>passwd</file> and <file>group</file> files of all
5785 Debian systems, new ids in this range being added
5786 automatically as the <tt>base-passwd</tt> package is
5791 Packages which need a single statically allocated
5792 uid or gid should use one of these; their
5793 maintainers should ask the <tt>base-passwd</tt>
5801 Dynamically allocated system users and groups.
5802 Packages which need a user or group, but can have
5803 this user or group allocated dynamically and
5804 differently on each system, should use <tt>adduser
5805 --system</tt> to create the group and/or user.
5806 <prgn>adduser</prgn> will check for the existence of
5807 the user or group, and if necessary choose an unused
5808 id based on the ranges specified in
5809 <file>adduser.conf</file>.
5813 <tag>1000-29999:</tag>
5816 Dynamically allocated user accounts. By default
5817 <prgn>adduser</prgn> will choose UIDs and GIDs for
5818 user accounts in this range, though
5819 <file>adduser.conf</file> may be used to modify this
5824 <tag>30000-59999:</tag>
5829 <tag>60000-64999:</tag>
5832 Globally allocated by the Debian project, but only
5833 created on demand. The ids are allocated centrally
5834 and statically, but the actual accounts are only
5835 created on users' systems on demand.
5839 These ids are for packages which are obscure or
5840 which require many statically-allocated ids. These
5841 packages should check for and create the accounts in
5842 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5843 <prgn>adduser</prgn> if it has this facility) if
5844 necessary. Packages which are likely to require
5845 further allocations should have a "hole" left after
5846 them in the allocation, to give them room to
5851 <tag>65000-65533:</tag>
5859 User <tt>nobody</tt>. The corresponding gid refers
5860 to the group <tt>nogroup</tt>.
5867 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5868 not</em> be used, because it is the error return
5877 <sect id="sysvinit">
5878 <heading>System run levels and <file>init.d</file> scripts</heading>
5880 <sect1 id="/etc/init.d">
5881 <heading>Introduction</heading>
5884 The <file>/etc/init.d</file> directory contains the scripts
5885 executed by <prgn>init</prgn> at boot time and when the
5886 init state (or "runlevel") is changed (see <manref
5887 name="init" section="8">).
5891 There are at least two different, yet functionally
5892 equivalent, ways of handling these scripts. For the sake
5893 of simplicity, this document describes only the symbolic
5894 link method. However, it must not be assumed by maintainer
5895 scripts that this method is being used, and any automated
5896 manipulation of the various runlevel behaviors by
5897 maintainer scripts must be performed using
5898 <prgn>update-rc.d</prgn> as described below and not by
5899 manually installing or removing symlinks. For information
5900 on the implementation details of the other method,
5901 implemented in the <tt>file-rc</tt> package, please refer
5902 to the documentation of that package.
5906 These scripts are referenced by symbolic links in the
5907 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5908 runlevels, <prgn>init</prgn> looks in the directory
5909 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5910 execute, where <tt><var>n</var></tt> is the runlevel that
5911 is being changed to, or <tt>S</tt> for the boot-up
5916 The names of the links all have the form
5917 <file>S<var>mm</var><var>script</var></file> or
5918 <file>K<var>mm</var><var>script</var></file> where
5919 <var>mm</var> is a two-digit number and <var>script</var>
5920 is the name of the script (this should be the same as the
5921 name of the actual script in <file>/etc/init.d</file>).
5925 When <prgn>init</prgn> changes runlevel first the targets
5926 of the links whose names start with a <tt>K</tt> are
5927 executed, each with the single argument <tt>stop</tt>,
5928 followed by the scripts prefixed with an <tt>S</tt>, each
5929 with the single argument <tt>start</tt>. (The links are
5930 those in the <file>/etc/rc<var>n</var>.d</file> directory
5931 corresponding to the new runlevel.) The <tt>K</tt> links
5932 are responsible for killing services and the <tt>S</tt>
5933 link for starting services upon entering the runlevel.
5937 For example, if we are changing from runlevel 2 to
5938 runlevel 3, init will first execute all of the <tt>K</tt>
5939 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5940 all of the <tt>S</tt> prefixed scripts in that directory.
5941 The links starting with <tt>K</tt> will cause the
5942 referred-to file to be executed with an argument of
5943 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5948 The two-digit number <var>mm</var> is used to determine
5949 the order in which to run the scripts: low-numbered links
5950 have their scripts run first. For example, the
5951 <tt>K20</tt> scripts will be executed before the
5952 <tt>K30</tt> scripts. This is used when a certain service
5953 must be started before another. For example, the name
5954 server <prgn>bind</prgn> might need to be started before
5955 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5956 can set up its access lists. In this case, the script
5957 that starts <prgn>bind</prgn> would have a lower number
5958 than the script that starts <prgn>inn</prgn> so that it
5960 <example compact="compact">
5967 The two runlevels 0 (halt) and 6 (reboot) are slightly
5968 different. In these runlevels, the links with an
5969 <tt>S</tt> prefix are still called after those with a
5970 <tt>K</tt> prefix, but they too are called with the single
5971 argument <tt>stop</tt>.
5976 <heading>Writing the scripts</heading>
5979 Packages that include daemons for system services should
5980 place scripts in <file>/etc/init.d</file> to start or stop
5981 services at boot time or during a change of runlevel.
5982 These scripts should be named
5983 <file>/etc/init.d/<var>package</var></file>, and they should
5984 accept one argument, saying what to do:
5987 <tag><tt>start</tt></tag>
5988 <item>start the service,</item>
5990 <tag><tt>stop</tt></tag>
5991 <item>stop the service,</item>
5993 <tag><tt>restart</tt></tag>
5994 <item>stop and restart the service if it's already running,
5995 otherwise start the service</item>
5997 <tag><tt>reload</tt></tag>
5998 <item><p>cause the configuration of the service to be
5999 reloaded without actually stopping and restarting
6002 <tag><tt>force-reload</tt></tag>
6003 <item>cause the configuration to be reloaded if the
6004 service supports this, otherwise restart the
6008 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6009 <tt>force-reload</tt> options should be supported by all
6010 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6015 The <file>init.d</file> scripts must ensure that they will
6016 behave sensibly (i.e., returning success and not starting
6017 multiple copies of a service) if invoked with <tt>start</tt>
6018 when the service is already running, or with <tt>stop</tt>
6019 when it isn't, and that they don't kill unfortunately-named
6020 user processes. The best way to achieve this is usually to
6021 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6026 If a service reloads its configuration automatically (as
6027 in the case of <prgn>cron</prgn>, for example), the
6028 <tt>reload</tt> option of the <file>init.d</file> script
6029 should behave as if the configuration has been reloaded
6034 The <file>/etc/init.d</file> scripts must be treated as
6035 configuration files, either (if they are present in the
6036 package, that is, in the .deb file) by marking them as
6037 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6038 by managing them correctly in the maintainer scripts (see
6039 <ref id="config-files">). This is important since we want
6040 to give the local system administrator the chance to adapt
6041 the scripts to the local system, e.g., to disable a
6042 service without de-installing the package, or to specify
6043 some special command line options when starting a service,
6044 while making sure their changes aren't lost during the next
6049 These scripts should not fail obscurely when the
6050 configuration files remain but the package has been
6051 removed, as configuration files remain on the system after
6052 the package has been removed. Only when <prgn>dpkg</prgn>
6053 is executed with the <tt>--purge</tt> option will
6054 configuration files be removed. In particular, as the
6055 <file>/etc/init.d/<var>package</var></file> script itself is
6056 usually a <tt>conffile</tt>, it will remain on the system
6057 if the package is removed but not purged. Therefore, you
6058 should include a <tt>test</tt> statement at the top of the
6060 <example compact="compact">
6061 test -f <var>program-executed-later-in-script</var> || exit 0
6066 Often there are some variables in the <file>init.d</file>
6067 scripts whose values control the behavior of the scripts,
6068 and which a system administrator is likely to want to
6069 change. As the scripts themselves are frequently
6070 <tt>conffile</tt>s, modifying them requires that the
6071 administrator merge in their changes each time the package
6072 is upgraded and the <tt>conffile</tt> changes. To ease
6073 the burden on the system administrator, such configurable
6074 values should not be placed directly in the script.
6075 Instead, they should be placed in a file in
6076 <file>/etc/default</file>, which typically will have the same
6077 base name as the <file>init.d</file> script. This extra file
6078 should be sourced by the script when the script runs. It
6079 must contain only variable settings and comments in SUSv3
6080 <prgn>sh</prgn> format. It may either be a
6081 <tt>conffile</tt> or a configuration file maintained by
6082 the package maintainer scripts. See <ref id="config-files">
6087 To ensure that vital configurable values are always
6088 available, the <file>init.d</file> script should set default
6089 values for each of the shell variables it uses, either
6090 before sourcing the <file>/etc/default/</file> file or
6091 afterwards using something like the <tt>:
6092 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6093 script must behave sensibly and not fail if the
6094 <file>/etc/default</file> file is deleted.
6098 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6099 as temporary filesystems<footnote>
6100 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6101 options in <file>/etc/default/rcS</file>.
6102 </footnote>, so the <file>init.d</file> scripts must handle this
6103 correctly. This will typically amount to creating any required
6104 subdirectories dynamically when the <file>init.d</file> script
6105 is run, rather than including them in the package and relying on
6106 <prgn>dpkg</prgn> to create them.
6111 <heading>Interfacing with the initscript system</heading>
6114 Maintainers should use the abstraction layer provided by
6115 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6116 programs to deal with initscripts in their packages'
6117 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6118 and <prgn>postrm</prgn>.
6122 Directly managing the /etc/rc?.d links and directly
6123 invoking the <file>/etc/init.d/</file> initscripts should
6124 be done only by packages providing the initscript
6125 subsystem (such as <prgn>sysv-rc</prgn> and
6126 <prgn>file-rc</prgn>).
6130 <heading>Managing the links</heading>
6133 The program <prgn>update-rc.d</prgn> is provided for
6134 package maintainers to arrange for the proper creation and
6135 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6136 or their functional equivalent if another method is being
6137 used. This may be used by maintainers in their packages'
6138 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6142 You must not include any <file>/etc/rc<var>n</var>.d</file>
6143 symbolic links in the actual archive or manually create or
6144 remove the symbolic links in maintainer scripts; you must
6145 use the <prgn>update-rc.d</prgn> program instead. (The
6146 former will fail if an alternative method of maintaining
6147 runlevel information is being used.) You must not include
6148 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6149 in the archive either. (Only the <tt>sysvinit</tt>
6154 By default <prgn>update-rc.d</prgn> will start services in
6155 each of the multi-user state runlevels (2, 3, 4, and 5)
6156 and stop them in the halt runlevel (0), the single-user
6157 runlevel (1) and the reboot runlevel (6). The system
6158 administrator will have the opportunity to customize
6159 runlevels by simply adding, moving, or removing the
6160 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6161 symbolic links are being used, or by modifying
6162 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6167 To get the default behavior for your package, put in your
6168 <prgn>postinst</prgn> script
6169 <example compact="compact">
6170 update-rc.d <var>package</var> defaults
6172 and in your <prgn>postrm</prgn>
6173 <example compact="compact">
6174 if [ "$1" = purge ]; then
6175 update-rc.d <var>package</var> remove
6177 </example>. Note that if your package changes runlevels
6178 or priority, you may have to remove and recreate the links,
6179 since otherwise the old links may persist. Refer to the
6180 documentation of <prgn>update-rc.d</prgn>.
6184 This will use a default sequence number of 20. If it does
6185 not matter when or in which order the <file>init.d</file>
6186 script is run, use this default. If it does, then you
6187 should talk to the maintainer of the <prgn>sysvinit</prgn>
6188 package or post to <tt>debian-devel</tt>, and they will
6189 help you choose a number.
6193 For more information about using <tt>update-rc.d</tt>,
6194 please consult its man page <manref name="update-rc.d"
6200 <heading>Running initscripts</heading>
6202 The program <prgn>invoke-rc.d</prgn> is provided to make
6203 it easier for package maintainers to properly invoke an
6204 initscript, obeying runlevel and other locally-defined
6205 constraints that might limit a package's right to start,
6206 stop and otherwise manage services. This program may be
6207 used by maintainers in their packages' scripts.
6211 The package maintainer scripts must use
6212 <prgn>invoke-rc.d</prgn> to invoke the
6213 <file>/etc/init.d/*</file> initscripts, instead of
6214 calling them directly.
6218 By default, <prgn>invoke-rc.d</prgn> will pass any
6219 action requests (start, stop, reload, restart...) to the
6220 <file>/etc/init.d</file> script, filtering out requests
6221 to start or restart a service out of its intended
6226 Most packages will simply need to change:
6227 <example compact="compact">/etc/init.d/<package>
6228 <action></example> in their <prgn>postinst</prgn>
6229 and <prgn>prerm</prgn> scripts to:
6230 <example compact="compact">
6231 if which invoke-rc.d >/dev/null 2>&1; then
6232 invoke-rc.d <var>package</var> <action>
6234 /etc/init.d/<var>package</var> <action>
6240 A package should register its initscript services using
6241 <prgn>update-rc.d</prgn> before it tries to invoke them
6242 using <prgn>invoke-rc.d</prgn>. Invocation of
6243 unregistered services may fail.
6247 For more information about using
6248 <prgn>invoke-rc.d</prgn>, please consult its man page
6249 <manref name="invoke-rc.d" section="8">.
6255 <heading>Boot-time initialization</heading>
6258 There used to be another directory, <file>/etc/rc.boot</file>,
6259 which contained scripts which were run once per machine
6260 boot. This has been deprecated in favour of links from
6261 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6262 described in <ref id="/etc/init.d">. Packages must not
6263 place files in <file>/etc/rc.boot</file>.
6268 <heading>Example</heading>
6271 An example on which you can base your
6272 <file>/etc/init.d</file> scripts is found in
6273 <file>/etc/init.d/skeleton</file>.
6280 <heading>Console messages from <file>init.d</file> scripts</heading>
6283 This section describes the formats to be used for messages
6284 written to standard output by the <file>/etc/init.d</file>
6285 scripts. The intent is to improve the consistency of
6286 Debian's startup and shutdown look and feel. For this
6287 reason, please look very carefully at the details. We want
6288 the messages to have the same format in terms of wording,
6289 spaces, punctuation and case of letters.
6293 Here is a list of overall rules that should be used for
6294 messages generated by <file>/etc/init.d</file> scripts.
6300 The message should fit in one line (fewer than 80
6301 characters), start with a capital letter and end with
6302 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6306 If the script is performing some time consuming task in
6307 the background (not merely starting or stopping a
6308 program, for instance), an ellipsis (three dots:
6309 <tt>...</tt>) should be output to the screen, with no
6310 leading or tailing whitespace or line feeds.
6314 The messages should appear as if the computer is telling
6315 the user what it is doing (politely :-), but should not
6316 mention "it" directly. For example, instead of:
6317 <example compact="compact">
6318 I'm starting network daemons: nfsd mountd.
6320 the message should say
6321 <example compact="compact">
6322 Starting network daemons: nfsd mountd.
6329 <tt>init.d</tt> script should use the following standard
6330 message formats for the situations enumerated below.
6336 <p>When daemons are started</p>
6339 If the script starts one or more daemons, the output
6340 should look like this (a single line, no leading
6342 <example compact="compact">
6343 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6345 The <var>description</var> should describe the
6346 subsystem the daemon or set of daemons are part of,
6347 while <var>daemon-1</var> up to <var>daemon-n</var>
6348 denote each daemon's name (typically the file name of
6353 For example, the output of <file>/etc/init.d/lpd</file>
6355 <example compact="compact">
6356 Starting printer spooler: lpd.
6361 This can be achieved by saying
6362 <example compact="compact">
6363 echo -n "Starting printer spooler: lpd"
6364 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6367 in the script. If there are more than one daemon to
6368 start, the output should look like this:
6369 <example compact="compact">
6370 echo -n "Starting remote file system services:"
6371 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6372 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6373 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6376 This makes it possible for the user to see what is
6377 happening and when the final daemon has been started.
6378 Care should be taken in the placement of white spaces:
6379 in the example above the system administrators can
6380 easily comment out a line if they don't want to start
6381 a specific daemon, while the displayed message still
6387 <p>When a system parameter is being set</p>
6390 If you have to set up different system parameters
6391 during the system boot, you should use this format:
6392 <example compact="compact">
6393 Setting <var>parameter</var> to "<var>value</var>".
6398 You can use a statement such as the following to get
6400 <example compact="compact">
6401 echo "Setting DNS domainname to \"$domainname\"."
6406 Note that the same symbol (<tt>"</tt>) is used for the left
6407 and right quotation marks. A grave accent (<tt>`</tt>) is
6408 not a quote character; neither is an apostrophe
6414 <p>When a daemon is stopped or restarted</p>
6417 When you stop or restart a daemon, you should issue a
6418 message identical to the startup message, except that
6419 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6420 or <tt>Restarting</tt> respectively.
6424 For example, stopping the printer daemon will look like
6426 <example compact="compact">
6427 Stopping printer spooler: lpd.
6433 <p>When something is executed</p>
6436 There are several examples where you have to run a
6437 program at system startup or shutdown to perform a
6438 specific task, for example, setting the system's clock
6439 using <prgn>netdate</prgn> or killing all processes
6440 when the system shuts down. Your message should look
6442 <example compact="compact">
6443 Doing something very useful...done.
6445 You should print the <tt>done.</tt> immediately after
6446 the job has been completed, so that the user is
6447 informed why they have to wait. You can get this
6449 <example compact="compact">
6450 echo -n "Doing something very useful..."
6459 <p>When the configuration is reloaded</p>
6462 When a daemon is forced to reload its configuration
6463 files you should use the following format:
6464 <example compact="compact">
6465 Reloading <var>description</var> configuration...done.
6467 where <var>description</var> is the same as in the
6468 daemon starting message.
6476 <heading>Cron jobs</heading>
6479 Packages must not modify the configuration file
6480 <file>/etc/crontab</file>, and they must not modify the files in
6481 <file>/var/spool/cron/crontabs</file>.</p>
6484 If a package wants to install a job that has to be executed
6485 via cron, it should place a file with the name of the
6486 package in one or more of the following directories:
6487 <example compact="compact">
6493 As these directory names imply, the files within them are
6494 executed on an hourly, daily, weekly, or monthly basis,
6495 respectively. The exact times are listed in
6496 <file>/etc/crontab</file>.</p>
6499 All files installed in any of these directories must be
6500 scripts (e.g., shell scripts or Perl scripts) so that they
6501 can easily be modified by the local system administrator.
6502 In addition, they must be treated as configuration files.
6506 If a certain job has to be executed at some other frequency or
6507 at a specific time, the package should install a file
6508 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6509 same syntax as <file>/etc/crontab</file> and is processed by
6510 <prgn>cron</prgn> automatically. The file must also be
6511 treated as a configuration file. (Note that entries in the
6512 <file>/etc/cron.d</file> directory are not handled by
6513 <prgn>anacron</prgn>. Thus, you should only use this
6514 directory for jobs which may be skipped if the system is not
6518 The scripts or crontab entries in these directories should
6519 check if all necessary programs are installed before they
6520 try to execute them. Otherwise, problems will arise when a
6521 package was removed but not purged since configuration files
6522 are kept on the system in this situation.</p>
6526 <heading>Menus</heading>
6529 The Debian <tt>menu</tt> package provides a standard
6530 interface between packages providing applications and
6531 <em>menu programs</em> (either X window managers or
6532 text-based menu programs such as <prgn>pdmenu</prgn>).
6536 All packages that provide applications that need not be
6537 passed any special command line arguments for normal
6538 operation should register a menu entry for those
6539 applications, so that users of the <tt>menu</tt> package
6540 will automatically get menu entries in their window
6541 managers, as well in shells like <tt>pdmenu</tt>.
6545 Menu entries should follow the current menu policy.
6549 The menu policy can be found in the <tt>menu-policy</tt>
6550 files in the <tt>debian-policy</tt> package.
6551 It is also available from the Debian web mirrors at
6552 <tt><url name="/doc/packaging-manuals/menu-policy/"
6553 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6557 Please also refer to the <em>Debian Menu System</em>
6558 documentation that comes with the <package>menu</package>
6559 package for information about how to register your
6565 <heading>Multimedia handlers</heading>
6568 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6569 is a mechanism for encoding files and data streams and
6570 providing meta-information about them, in particular their
6571 type (e.g. audio or video) and format (e.g. PNG, HTML,
6576 Registration of MIME type handlers allows programs like mail
6577 user agents and web browsers to invoke these handlers to
6578 view, edit or display MIME types they don't support directly.
6582 Packages which provide the ability to view/show/play,
6583 compose, edit or print MIME types should register themselves
6584 as such following the current MIME support policy.
6588 The MIME support policy can be found in the <tt>mime-policy</tt>
6589 files in the <tt>debian-policy</tt> package.
6590 It is also available from the Debian web mirrors at
6591 <tt><url name="/doc/packaging-manuals/mime-policy/"
6592 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6598 <heading>Keyboard configuration</heading>
6601 To achieve a consistent keyboard configuration so that all
6602 applications interpret a keyboard event the same way, all
6603 programs in the Debian distribution must be configured to
6604 comply with the following guidelines.
6608 The following keys must have the specified interpretations:
6611 <tag><tt><--</tt></tag>
6612 <item>delete the character to the left of the cursor</item>
6614 <tag><tt>Delete</tt></tag>
6615 <item>delete the character to the right of the cursor</item>
6617 <tag><tt>Control+H</tt></tag>
6618 <item>emacs: the help prefix</item>
6621 The interpretation of any keyboard events should be
6622 independent of the terminal that is used, be it a virtual
6623 console, an X terminal emulator, an rlogin/telnet session,
6628 The following list explains how the different programs
6629 should be set up to achieve this:
6635 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6639 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6643 X translations are set up to make
6644 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6645 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6646 is the vt220 escape code for the "delete character"
6647 key). This must be done by loading the X resources
6648 using <prgn>xrdb</prgn> on all local X displays, not
6649 using the application defaults, so that the
6650 translation resources used correspond to the
6651 <prgn>xmodmap</prgn> settings.
6655 The Linux console is configured to make
6656 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6657 generate <tt>ESC [ 3 ~</tt>.
6661 X applications are configured so that <tt><</tt>
6662 deletes left, and <tt>Delete</tt> deletes right. Motif
6663 applications already work like this.
6667 Terminals should have <tt>stty erase ^?</tt> .
6671 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6672 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6673 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6677 Emacs is programmed to map <tt>KB_Backspace</tt> or
6678 the <tt>stty erase</tt> character to
6679 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6680 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6681 <tt>^H</tt> to <tt>help</tt> as always.
6685 Other applications use the <tt>stty erase</tt>
6686 character and <tt>kdch1</tt> for the two delete keys,
6687 with ASCII DEL being "delete previous character" and
6688 <tt>kdch1</tt> being "delete character under
6696 This will solve the problem except for the following
6703 Some terminals have a <tt><--</tt> key that cannot
6704 be made to produce anything except <tt>^H</tt>. On
6705 these terminals Emacs help will be unavailable on
6706 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6707 character takes precedence in Emacs, and has been set
6708 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6709 available) can be used instead.
6713 Some operating systems use <tt>^H</tt> for <tt>stty
6714 erase</tt>. However, modern telnet versions and all
6715 rlogin versions propagate <tt>stty</tt> settings, and
6716 almost all UNIX versions honour <tt>stty erase</tt>.
6717 Where the <tt>stty</tt> settings are not propagated
6718 correctly, things can be made to work by using
6719 <tt>stty</tt> manually.
6723 Some systems (including previous Debian versions) use
6724 <prgn>xmodmap</prgn> to arrange for both
6725 <tt><--</tt> and <tt>Delete</tt> to generate
6726 <tt>KB_Delete</tt>. We can change the behavior of
6727 their X clients using the same X resources that we use
6728 to do it for our own clients, or configure our clients
6729 using their resources when things are the other way
6730 around. On displays configured like this
6731 <tt>Delete</tt> will not work, but <tt><--</tt>
6736 Some operating systems have different <tt>kdch1</tt>
6737 settings in their <tt>terminfo</tt> database for
6738 <tt>xterm</tt> and others. On these systems the
6739 <tt>Delete</tt> key will not work correctly when you
6740 log in from a system conforming to our policy, but
6741 <tt><--</tt> will.
6748 <heading>Environment variables</heading>
6751 A program must not depend on environment variables to get
6752 reasonable defaults. (That's because these environment
6753 variables would have to be set in a system-wide
6754 configuration file like <file>/etc/profile</file>, which is not
6755 supported by all shells.)
6759 If a program usually depends on environment variables for its
6760 configuration, the program should be changed to fall back to
6761 a reasonable default configuration if these environment
6762 variables are not present. If this cannot be done easily
6763 (e.g., if the source code of a non-free program is not
6764 available), the program must be replaced by a small
6765 "wrapper" shell script which sets the environment variables
6766 if they are not already defined, and calls the original program.
6770 Here is an example of a wrapper script for this purpose:
6772 <example compact="compact">
6774 BAR=${BAR:-/var/lib/fubar}
6776 exec /usr/lib/foo/foo "$@"
6781 Furthermore, as <file>/etc/profile</file> is a configuration
6782 file of the <prgn>base-files</prgn> package, other packages must
6783 not put any environment variables or other commands into that
6788 <sect id="doc-base">
6789 <heading>Registering Documents using doc-base</heading>
6792 The <package>doc-base</package> package implements a
6793 flexible mechanism for handling and presenting
6794 documentation. The recommended practice is for every Debian
6795 package that provides online documentation (other than just
6796 manual pages) to register these documents with
6797 <package>doc-base</package> by installing a
6798 <package>doc-base</package> control file via the
6799 <prgn/install-docs/ script at installation time and
6800 de-register the manuals again when the package is removed.
6803 Please refer to the documentation that comes with the
6804 <package>doc-base</package> package for information and
6813 <heading>Files</heading>
6816 <heading>Binaries</heading>
6819 Two different packages must not install programs with
6820 different functionality but with the same filenames. (The
6821 case of two programs having the same functionality but
6822 different implementations is handled via "alternatives" or
6823 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6824 <ref id="conflicts"> respectively.) If this case happens,
6825 one of the programs must be renamed. The maintainers should
6826 report this to the <tt>debian-devel</tt> mailing list and
6827 try to find a consensus about which program will have to be
6828 renamed. If a consensus cannot be reached, <em>both</em>
6829 programs must be renamed.
6833 By default, when a package is being built, any binaries
6834 created should include debugging information, as well as
6835 being compiled with optimization. You should also turn on
6836 as many reasonable compilation warnings as possible; this
6837 makes life easier for porters, who can then look at build
6838 logs for possible problems. For the C programming language,
6839 this means the following compilation parameters should be
6841 <example compact="compact">
6843 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6845 INSTALL = install -s # (or use strip on the files in debian/tmp)
6850 Note that by default all installed binaries should be stripped,
6851 either by using the <tt>-s</tt> flag to
6852 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6853 the binaries after they have been copied into
6854 <file>debian/tmp</file> but before the tree is made into a
6859 Although binaries in the build tree should be compiled with
6860 debugging information by default, it can often be difficult to
6861 debug programs if they are also subjected to compiler
6862 optimization. For this reason, it is recommended to support the
6863 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6864 (see <ref id="debianrules-options">). This variable can contain
6865 several flags to change how a package is compiled and built.
6869 It is up to the package maintainer to decide what
6870 compilation options are best for the package. Certain
6871 binaries (such as computationally-intensive programs) will
6872 function better with certain flags (<tt>-O3</tt>, for
6873 example); feel free to use them. Please use good judgment
6874 here. Don't use flags for the sake of it; only use them
6875 if there is good reason to do so. Feel free to override
6876 the upstream author's ideas about which compilation
6877 options are best: they are often inappropriate for our
6883 <sect id="libraries">
6884 <heading>Libraries</heading>
6887 If the package is <strong>architecture: any</strong>, then
6888 the shared library compilation and linking flags must have
6889 <tt>-fPIC</tt>, or the package shall not build on some of
6890 the supported architectures<footnote>
6892 If you are using GCC, <tt>-fPIC</tt> produces code with
6893 relocatable position independent code, which is required for
6894 most architectures to create a shared library, with i386 and
6895 perhaps some others where non position independent code is
6896 permitted in a shared library.
6899 Position independent code may have a performance penalty,
6900 especially on <tt>i386</tt>. However, in most cases the
6901 speed penalty must be measured against the memory wasted on
6902 the few architectures where non position independent code is
6905 </footnote>. Any exception to this rule must be discussed on
6906 the mailing list <em>debian-devel@lists.debian.org</em>, and
6907 a rough consensus obtained. The reasons for not compiling
6908 with <tt>-fPIC</tt> flag must be recorded in the file
6909 <tt>README.Debian</tt>, and care must be taken to either
6910 restrict the architecture or arrange for <tt>-fPIC</tt> to
6911 be used on architectures where it is required.<footnote>
6913 Some of the reasons why this might be required is if the
6914 library contains hand crafted assembly code that is not
6915 relocatable, the speed penalty is excessive for compute
6916 intensive libs, and similar reasons.
6921 As to the static libraries, the common case is not to have
6922 relocatable code, since there is no benefit, unless in specific
6923 cases; therefore the static version must not be compiled
6924 with the <tt>-fPIC</tt> flag. Any exception to this rule
6925 should be discussed on the mailing list
6926 <em>debian-devel@lists.debian.org</em>, and the reasons for
6927 compiling with the <tt>-fPIC</tt> flag must be recorded in
6928 the file <tt>README.Debian</tt>. <footnote>
6930 Some of the reasons for linking static libraries with
6931 the <tt>-fPIC</tt> flag are if, for example, one needs a
6932 Perl API for a library that is under rapid development,
6933 and has an unstable API, so shared libraries are
6934 pointless at this phase of the library's development. In
6935 that case, since Perl needs a library with relocatable
6936 code, it may make sense to create a static library with
6937 relocatable code. Another reason cited is if you are
6938 distilling various libraries into a common shared
6939 library, like <tt>mklibs</tt> does in the Debian
6945 In other words, if both a shared and a static library is
6946 being built, each source unit (<tt>*.c</tt>, for example,
6947 for C files) will need to be compiled twice, for the normal
6951 You must specify the gcc option <tt>-D_REENTRANT</tt>
6952 when building a library (either static or shared) to make
6953 the library compatible with LinuxThreads.
6957 Although not enforced by the build tools, shared libraries
6958 must be linked against all libraries that they use symbols from
6959 in the same way that binaries are. This ensures the correct
6960 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6961 system and guarantees that all libraries can be safely opened
6962 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6963 option <tt>-Wl,-z,defs</tt> when building a shared library.
6964 Since this option enforces symbol resolution at build time,
6965 a missing library reference will be caught early as a fatal
6970 All installed shared libraries should be stripped with
6971 <example compact="compact">
6972 strip --strip-unneeded <var>your-lib</var>
6974 (The option <tt>--strip-unneeded</tt> makes
6975 <prgn>strip</prgn> remove only the symbols which aren't
6976 needed for relocation processing.) Shared libraries can
6977 function perfectly well when stripped, since the symbols for
6978 dynamic linking are in a separate part of the ELF object
6980 You might also want to use the options
6981 <tt>--remove-section=.comment</tt> and
6982 <tt>--remove-section=.note</tt> on both shared libraries
6983 and executables, and <tt>--strip-debug</tt> on static
6989 Note that under some circumstances it may be useful to
6990 install a shared library unstripped, for example when
6991 building a separate package to support debugging.
6995 Shared object files (often <file>.so</file> files) that are not
6996 public libraries, that is, they are not meant to be linked
6997 to by third party executables (binaries of other packages),
6998 should be installed in subdirectories of the
6999 <file>/usr/lib</file> directory. Such files are exempt from the
7000 rules that govern ordinary shared libraries, except that
7001 they must not be installed executable and should be
7003 A common example are the so-called "plug-ins",
7004 internal shared objects that are dynamically loaded by
7005 programs using <manref name="dlopen" section="3">.
7010 Packages containing shared libraries that may be linked to
7011 by other packages' binaries, but which for some
7012 <em>compelling</em> reason can not be installed in
7013 <file>/usr/lib</file> directory, may install the shared library
7014 files in subdirectories of the <file>/usr/lib</file> directory,
7015 in which case they should arrange to add that directory in
7016 <file>/etc/ld.so.conf</file> in the package's post-installation
7017 script, and remove it in the package's post-removal script.
7021 An ever increasing number of packages are using
7022 <prgn>libtool</prgn> to do their linking. The latest GNU
7023 libtools (>= 1.3a) can take advantage of the metadata in the
7024 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7025 files). The main advantage of <prgn>libtool</prgn>'s
7026 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7027 store and subsequently access metadata with respect to the
7028 libraries it builds. <prgn>libtool</prgn> will search for
7029 those files, which contain a lot of useful information about
7030 a library (such as library dependency information for static
7031 linking). Also, they're <em>essential</em> for programs
7032 using <tt>libltdl</tt>.<footnote>
7033 Although <prgn>libtool</prgn> is fully capable of
7034 linking against shared libraries which don't have
7035 <tt>.la</tt> files, as it is a mere shell script it can
7036 add considerably to the build time of a
7037 <prgn>libtool</prgn>-using package if that shell script
7038 has to derive all this information from first principles
7039 for each library every time it is linked. With the
7040 advent of <prgn>libtool</prgn> version 1.4 (and to a
7041 lesser extent <prgn>libtool</prgn> version 1.3), the
7042 <file>.la</file> files also store information about
7043 inter-library dependencies which cannot necessarily be
7044 derived after the <file>.la</file> file is deleted.
7049 Packages that use <prgn>libtool</prgn> to create shared
7050 libraries should include the <file>.la</file> files in the
7051 <tt>-dev</tt> package, unless the package relies on
7052 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7053 the <tt>.la</tt> files must go in the run-time library
7058 You must make sure that you use only released versions of
7059 shared libraries to build your packages; otherwise other
7060 users will not be able to run your binaries
7061 properly. Producing source packages that depend on
7062 unreleased compilers is also usually a bad
7069 <heading>Shared libraries</heading>
7071 This section has moved to <ref id="sharedlibs">.
7077 <heading>Scripts</heading>
7080 All command scripts, including the package maintainer
7081 scripts inside the package and used by <prgn>dpkg</prgn>,
7082 should have a <tt>#!</tt> line naming the shell to be used
7087 In the case of Perl scripts this should be
7088 <tt>#!/usr/bin/perl</tt>.
7092 When scripts are installed into a directory in the system
7093 PATH, the script name should not include an extension such
7094 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7095 language currently used to implement it.
7098 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7099 should almost certainly start with <tt>set -e</tt> so that
7100 errors are detected. Every script should use
7101 <tt>set -e</tt> or check the exit status of <em>every</em>
7106 Scripts may assume that <file>/bin/sh</file> implements the
7107 SUSv3 Shell Command Language<footnote>
7108 Single UNIX Specification, version 3, which is also IEEE
7109 1003.1-2004 (POSIX), and is available on the World Wide Web
7110 from <url id="http://www.unix.org/version3/online.html"
7111 name="The Open Group"> after free
7112 registration.</footnote>
7113 plus the following additional features not mandated by
7115 These features are in widespread use in the Linux community
7116 and are implemented in all of bash, dash, and ksh, the most
7117 common shells users may wish to use as <file>/bin/sh</file>.
7120 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7121 must not generate a newline.</item>
7122 <item><tt>test</tt>, if implemented as a shell built-in, must
7123 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7125 <item><tt>local</tt> to create a scoped variable must be
7126 supported, including listing multiple variables in a single
7127 local command and assigning a value to a variable at the
7128 same time as localizing it. <tt>local</tt> may or
7129 may not preserve the variable value from an outer scope if
7130 no assignment is present. Uses such as:
7134 # ... use a, b, c, d ...
7137 must be supported and must set the value of <tt>c</tt> to
7141 If a shell script requires non-SUSv3 features from the shell
7142 interpreter other than those listed above, the appropriate shell
7143 must be specified in the first line of the script (e.g.,
7144 <tt>#!/bin/bash</tt>) and the package must depend on the package
7145 providing the shell (unless the shell package is marked
7146 "Essential", as in the case of <prgn>bash</prgn>).
7150 You may wish to restrict your script to SUSv3 features plus the
7151 above set when possible so that it may use <file>/bin/sh</file>
7152 as its interpreter. If your script works with <prgn>dash</prgn>
7153 (originally called <prgn>ash</prgn>), it probably complies with
7154 the above requirements, but if you are in doubt, use
7155 <file>/bin/bash</file>.
7159 Perl scripts should check for errors when making any
7160 system calls, including <tt>open</tt>, <tt>print</tt>,
7161 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7165 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7166 scripting languages. See <em>Csh Programming Considered
7167 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7168 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7169 If an upstream package comes with <prgn>csh</prgn> scripts
7170 then you must make sure that they start with
7171 <tt>#!/bin/csh</tt> and make your package depend on the
7172 <prgn>c-shell</prgn> virtual package.
7176 Any scripts which create files in world-writeable
7177 directories (e.g., in <file>/tmp</file>) must use a
7178 mechanism which will fail atomically if a file with the same
7179 name already exists.
7183 The Debian base system provides the <prgn>tempfile</prgn>
7184 and <prgn>mktemp</prgn> utilities for use by scripts for
7191 <heading>Symbolic links</heading>
7194 In general, symbolic links within a top-level directory
7195 should be relative, and symbolic links pointing from one
7196 top-level directory into another should be absolute. (A
7197 top-level directory is a sub-directory of the root
7198 directory <file>/</file>.)
7202 In addition, symbolic links should be specified as short as
7203 possible, i.e., link targets like <file>foo/../bar</file> are
7208 Note that when creating a relative link using
7209 <prgn>ln</prgn> it is not necessary for the target of the
7210 link to exist relative to the working directory you're
7211 running <prgn>ln</prgn> from, nor is it necessary to change
7212 directory to the directory where the link is to be made.
7213 Simply include the string that should appear as the target
7214 of the link (this will be a pathname relative to the
7215 directory in which the link resides) as the first argument
7220 For example, in your <prgn>Makefile</prgn> or
7221 <file>debian/rules</file>, you can do things like:
7222 <example compact="compact">
7223 ln -fs gcc $(prefix)/bin/cc
7224 ln -fs gcc debian/tmp/usr/bin/cc
7225 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7226 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7231 A symbolic link pointing to a compressed file should always
7232 have the same file extension as the referenced file. (For
7233 example, if a file <file>foo.gz</file> is referenced by a
7234 symbolic link, the filename of the link has to end with
7235 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7240 <heading>Device files</heading>
7243 Packages must not include device files in the package file
7248 If a package needs any special device files that are not
7249 included in the base system, it must call
7250 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7251 after notifying the user<footnote>
7252 This notification could be done via a (low-priority)
7253 debconf message, or an echo (printf) statement.
7258 Packages must not remove any device files in the
7259 <prgn>postrm</prgn> or any other script. This is left to the
7260 system administrator.
7264 Debian uses the serial devices
7265 <file>/dev/ttyS*</file>. Programs using the old
7266 <file>/dev/cu*</file> devices should be changed to use
7267 <file>/dev/ttyS*</file>.
7271 <sect id="config-files">
7272 <heading>Configuration files</heading>
7275 <heading>Definitions</heading>
7279 <tag>configuration file</tag>
7281 A file that affects the operation of a program, or
7282 provides site- or host-specific information, or
7283 otherwise customizes the behavior of a program.
7284 Typically, configuration files are intended to be
7285 modified by the system administrator (if needed or
7286 desired) to conform to local policy or to provide
7287 more useful site-specific behavior.
7290 <tag><tt>conffile</tt></tag>
7292 A file listed in a package's <tt>conffiles</tt>
7293 file, and is treated specially by <prgn>dpkg</prgn>
7294 (see <ref id="configdetails">).
7300 The distinction between these two is important; they are
7301 not interchangeable concepts. Almost all
7302 <tt>conffile</tt>s are configuration files, but many
7303 configuration files are not <tt>conffiles</tt>.
7307 As noted elsewhere, <file>/etc/init.d</file> scripts,
7308 <file>/etc/default</file> files, scripts installed in
7309 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7310 configuration installed in <file>/etc/cron.d</file> must be
7311 treated as configuration files. In general, any script that
7312 embeds configuration information is de-facto a configuration
7313 file and should be treated as such.
7318 <heading>Location</heading>
7321 Any configuration files created or used by your package
7322 must reside in <file>/etc</file>. If there are several,
7323 consider creating a subdirectory of <file>/etc</file>
7324 named after your package.
7328 If your package creates or uses configuration files
7329 outside of <file>/etc</file>, and it is not feasible to modify
7330 the package to use <file>/etc</file> directly, put the files
7331 in <file>/etc</file> and create symbolic links to those files
7332 from the location that the package requires.
7337 <heading>Behavior</heading>
7340 Configuration file handling must conform to the following
7342 <list compact="compact">
7344 local changes must be preserved during a package
7348 configuration files must be preserved when the
7349 package is removed, and only deleted when the
7356 The easy way to achieve this behavior is to make the
7357 configuration file a <tt>conffile</tt>. This is
7358 appropriate only if it is possible to distribute a default
7359 version that will work for most installations, although
7360 some system administrators may choose to modify it. This
7361 implies that the default version will be part of the
7362 package distribution, and must not be modified by the
7363 maintainer scripts during installation (or at any other
7368 In order to ensure that local changes are preserved
7369 correctly, no package may contain or make hard links to
7370 conffiles.<footnote>
7371 Rationale: There are two problems with hard links.
7372 The first is that some editors break the link while
7373 editing one of the files, so that the two files may
7374 unwittingly become unlinked and different. The second
7375 is that <prgn>dpkg</prgn> might break the hard link
7376 while upgrading <tt>conffile</tt>s.
7381 The other way to do it is via the maintainer scripts. In
7382 this case, the configuration file must not be listed as a
7383 <tt>conffile</tt> and must not be part of the package
7384 distribution. If the existence of a file is required for
7385 the package to be sensibly configured it is the
7386 responsibility of the package maintainer to provide
7387 maintainer scripts which correctly create, update and
7388 maintain the file and remove it on purge. (See <ref
7389 id="maintainerscripts"> for more information.) These
7390 scripts must be idempotent (i.e., must work correctly if
7391 <prgn>dpkg</prgn> needs to re-run them due to errors
7392 during installation or removal), must cope with all the
7393 variety of ways <prgn>dpkg</prgn> can call maintainer
7394 scripts, must not overwrite or otherwise mangle the user's
7395 configuration without asking, must not ask unnecessary
7396 questions (particularly during upgrades), and must
7397 otherwise be good citizens.
7401 The scripts are not required to configure every possible
7402 option for the package, but only those necessary to get
7403 the package running on a given system. Ideally the
7404 sysadmin should not have to do any configuration other
7405 than that done (semi-)automatically by the
7406 <prgn>postinst</prgn> script.
7410 A common practice is to create a script called
7411 <file><var>package</var>-configure</file> and have the
7412 package's <prgn>postinst</prgn> call it if and only if the
7413 configuration file does not already exist. In certain
7414 cases it is useful for there to be an example or template
7415 file which the maintainer scripts use. Such files should
7416 be in <file>/usr/share/<var>package</var></file> or
7417 <file>/usr/lib/<var>package</var></file> (depending on whether
7418 they are architecture-independent or not). There should
7419 be symbolic links to them from
7420 <file>/usr/share/doc/<var>package</var>/examples</file> if
7421 they are examples, and should be perfectly ordinary
7422 <prgn>dpkg</prgn>-handled files (<em>not</em>
7423 configuration files).
7427 These two styles of configuration file handling must
7428 not be mixed, for that way lies madness:
7429 <prgn>dpkg</prgn> will ask about overwriting the file
7430 every time the package is upgraded.
7435 <heading>Sharing configuration files</heading>
7438 Packages which specify the same file as a
7439 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7440 with each other. (This is an instance of the general rule
7441 about not sharing files. Note that neither alternatives
7442 nor diversions are likely to be appropriate in this case;
7443 in particular, <prgn>dpkg</prgn> does not handle diverted
7444 <tt>conffile</tt>s well.)
7448 The maintainer scripts must not alter a <tt>conffile</tt>
7449 of <em>any</em> package, including the one the scripts
7454 If two or more packages use the same configuration file
7455 and it is reasonable for both to be installed at the same
7456 time, one of these packages must be defined as
7457 <em>owner</em> of the configuration file, i.e., it will be
7458 the package which handles that file as a configuration
7459 file. Other packages that use the configuration file must
7460 depend on the owning package if they require the
7461 configuration file to operate. If the other package will
7462 use the configuration file if present, but is capable of
7463 operating without it, no dependency need be declared.
7467 If it is desirable for two or more related packages to
7468 share a configuration file <em>and</em> for all of the
7469 related packages to be able to modify that configuration
7470 file, then the following should be done:
7471 <enumlist compact="compact">
7473 One of the related packages (the "owning" package)
7474 will manage the configuration file with maintainer
7475 scripts as described in the previous section.
7478 The owning package should also provide a program
7479 that the other packages may use to modify the
7483 The related packages must use the provided program
7484 to make any desired modifications to the
7485 configuration file. They should either depend on
7486 the core package to guarantee that the configuration
7487 modifier program is available or accept gracefully
7488 that they cannot modify the configuration file if it
7489 is not. (This is in addition to the fact that the
7490 configuration file may not even be present in the
7497 Sometimes it's appropriate to create a new package which
7498 provides the basic infrastructure for the other packages
7499 and which manages the shared configuration files. (The
7500 <tt>sgml-base</tt> package is a good example.)
7505 <heading>User configuration files ("dotfiles")</heading>
7508 The files in <file>/etc/skel</file> will automatically be
7509 copied into new user accounts by <prgn>adduser</prgn>.
7510 No other program should reference the files in
7511 <file>/etc/skel</file>.
7515 Therefore, if a program needs a dotfile to exist in
7516 advance in <file>$HOME</file> to work sensibly, that dotfile
7517 should be installed in <file>/etc/skel</file> and treated as a
7522 However, programs that require dotfiles in order to
7523 operate sensibly are a bad thing, unless they do create
7524 the dotfiles themselves automatically.
7528 Furthermore, programs should be configured by the Debian
7529 default installation to behave as closely to the upstream
7530 default behavior as possible.
7534 Therefore, if a program in a Debian package needs to be
7535 configured in some way in order to operate sensibly, that
7536 should be done using a site-wide configuration file placed
7537 in <file>/etc</file>. Only if the program doesn't support a
7538 site-wide default configuration and the package maintainer
7539 doesn't have time to add it may a default per-user file be
7540 placed in <file>/etc/skel</file>.
7544 <file>/etc/skel</file> should be as empty as we can make it.
7545 This is particularly true because there is no easy (or
7546 necessarily desirable) mechanism for ensuring that the
7547 appropriate dotfiles are copied into the accounts of
7548 existing users when a package is installed.
7554 <heading>Log files</heading>
7556 Log files should usually be named
7557 <file>/var/log/<var>package</var>.log</file>. If you have many
7558 log files, or need a separate directory for permission
7559 reasons (<file>/var/log</file> is writable only by
7560 <file>root</file>), you should usually create a directory named
7561 <file>/var/log/<var>package</var></file> and place your log
7566 Log files must be rotated occasionally so that they don't
7567 grow indefinitely; the best way to do this is to drop a log
7568 rotation configuration file into the directory
7569 <file>/etc/logrotate.d</file> and use the facilities provided by
7570 logrotate.<footnote>
7572 The traditional approach to log files has been to set up
7573 <em>ad hoc</em> log rotation schemes using simple shell
7574 scripts and cron. While this approach is highly
7575 customizable, it requires quite a lot of sysadmin work.
7576 Even though the original Debian system helped a little
7577 by automatically installing a system which can be used
7578 as a template, this was deemed not enough.
7582 The use of <prgn>logrotate</prgn>, a program developed
7583 by Red Hat, is better, as it centralizes log management.
7584 It has both a configuration file
7585 (<file>/etc/logrotate.conf</file>) and a directory where
7586 packages can drop their individual log rotation
7587 configurations (<file>/etc/logrotate.d</file>).
7590 Here is a good example for a logrotate config
7591 file (for more information see <manref name="logrotate"
7593 <example compact="compact">
7594 /var/log/foo/*.log {
7599 /etc/init.d/foo force-reload
7603 This rotates all files under <file>/var/log/foo</file>, saves 12
7604 compressed generations, and forces the daemon to reload its
7605 configuration information after the log rotation.
7609 Log files should be removed when the package is
7610 purged (but not when it is only removed). This should be
7611 done by the <prgn>postrm</prgn> script when it is called
7612 with the argument <tt>purge</tt> (see <ref
7613 id="removedetails">).
7618 <heading>Permissions and owners</heading>
7621 The rules in this section are guidelines for general use.
7622 If necessary you may deviate from the details below.
7623 However, if you do so you must make sure that what is done
7624 is secure and you should try to be as consistent as possible
7625 with the rest of the system. You should probably also
7626 discuss it on <prgn>debian-devel</prgn> first.
7630 Files should be owned by <tt>root:root</tt>, and made
7631 writable only by the owner and universally readable (and
7632 executable, if appropriate), that is mode 644 or 755.
7636 Directories should be mode 755 or (for group-writability)
7637 mode 2775. The ownership of the directory should be
7638 consistent with its mode: if a directory is mode 2775, it
7639 should be owned by the group that needs write access to
7642 When a package is upgraded, and the owner or permissions
7643 of a file included in the package has changed, dpkg
7644 arranges for the ownership and permissions to be
7645 correctly set upon installation. However, this does not
7646 extend to directories; the permissions and ownership of
7647 directories already on the system does not change on
7648 install or upgrade of packages. This makes sense, since
7649 otherwise common directories like <tt>/usr</tt> would
7650 always be in flux. To correctly change permissions of a
7651 directory the package owns, explicit action is required,
7652 usually in the <tt>postinst</tt> script. Care must be
7653 taken to handle downgrades as well, in that case.
7660 Setuid and setgid executables should be mode 4755 or 2755
7661 respectively, and owned by the appropriate user or group.
7662 They should not be made unreadable (modes like 4711 or
7663 2711 or even 4111); doing so achieves no extra security,
7664 because anyone can find the binary in the freely available
7665 Debian package; it is merely inconvenient. For the same
7666 reason you should not restrict read or execute permissions
7667 on non-set-id executables.
7671 Some setuid programs need to be restricted to particular
7672 sets of users, using file permissions. In this case they
7673 should be owned by the uid to which they are set-id, and by
7674 the group which should be allowed to execute them. They
7675 should have mode 4754; again there is no point in making
7676 them unreadable to those users who must not be allowed to
7681 It is possible to arrange that the system administrator can
7682 reconfigure the package to correspond to their local
7683 security policy by changing the permissions on a binary:
7684 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7685 described below.<footnote>
7686 Ordinary files installed by <prgn>dpkg</prgn> (as
7687 opposed to <tt>conffile</tt>s and other similar objects)
7688 normally have their permissions reset to the distributed
7689 permissions when the package is reinstalled. However,
7690 the use of <prgn>dpkg-statoverride</prgn> overrides this
7691 default behavior. If you use this method, you should
7692 remember to describe <prgn>dpkg-statoverride</prgn> in
7693 the package documentation; being a relatively new
7694 addition to Debian, it is probably not yet well-known.
7696 Another method you should consider is to create a group for
7697 people allowed to use the program(s) and make any setuid
7698 executables executable only by that group.
7702 If you need to create a new user or group for your package
7703 there are two possibilities. Firstly, you may need to
7704 make some files in the binary package be owned by this
7705 user or group, or you may need to compile the user or
7706 group id (rather than just the name) into the binary
7707 (though this latter should be avoided if possible, as in
7708 this case you need a statically allocated id).</p>
7711 If you need a statically allocated id, you must ask for a
7712 user or group id from the <tt>base-passwd</tt> maintainer,
7713 and must not release the package until you have been
7714 allocated one. Once you have been allocated one you must
7715 either make the package depend on a version of the
7716 <tt>base-passwd</tt> package with the id present in
7717 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7718 your package to create the user or group itself with the
7719 correct id (using <tt>adduser</tt>) in its
7720 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7721 the <prgn>postinst</prgn> is to be preferred if it is
7722 possible, otherwise a pre-dependency will be needed on the
7723 <tt>adduser</tt> package.)
7727 On the other hand, the program might be able to determine
7728 the uid or gid from the user or group name at runtime, so
7729 that a dynamically allocated id can be used. In this case
7730 you should choose an appropriate user or group name,
7731 discussing this on <prgn>debian-devel</prgn> and checking
7732 with the <package/base-passwd/ maintainer that it is unique and that
7733 they do not wish you to use a statically allocated id
7734 instead. When this has been checked you must arrange for
7735 your package to create the user or group if necessary using
7736 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7737 <prgn>postinst</prgn> script (again, the latter is to be
7738 preferred if it is possible).
7742 Note that changing the numeric value of an id associated
7743 with a name is very difficult, and involves searching the
7744 file system for all appropriate files. You need to think
7745 carefully whether a static or dynamic id is required, since
7746 changing your mind later will cause problems.
7749 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7751 This section is not intended as policy, but as a
7752 description of the use of <prgn>dpkg-statoverride</prgn>.
7756 If a system administrator wishes to have a file (or
7757 directory or other such thing) installed with owner and
7758 permissions different from those in the distributed Debian
7759 package, they can use the <prgn>dpkg-statoverride</prgn>
7760 program to instruct <prgn>dpkg</prgn> to use the different
7761 settings every time the file is installed. Thus the
7762 package maintainer should distribute the files with their
7763 normal permissions, and leave it for the system
7764 administrator to make any desired changes. For example, a
7765 daemon which is normally required to be setuid root, but
7766 in certain situations could be used without being setuid,
7767 should be installed setuid in the <tt>.deb</tt>. Then the
7768 local system administrator can change this if they wish.
7769 If there are two standard ways of doing it, the package
7770 maintainer can use <tt>debconf</tt> to find out the
7771 preference, and call <prgn>dpkg-statoverride</prgn> in the
7772 maintainer script if necessary to accommodate the system
7773 administrator's choice. Care must be taken during
7774 upgrades to not override an existing setting.
7778 Given the above, <prgn>dpkg-statoverride</prgn> is
7779 essentially a tool for system administrators and would not
7780 normally be needed in the maintainer scripts. There is
7781 one type of situation, though, where calls to
7782 <prgn>dpkg-statoverride</prgn> would be needed in the
7783 maintainer scripts, and that involves packages which use
7784 dynamically allocated user or group ids. In such a
7785 situation, something like the following idiom can be very
7786 helpful in the package's <prgn>postinst</prgn>, where
7787 <tt>sysuser</tt> is a dynamically allocated id:
7789 for i in /usr/bin/foo /usr/sbin/bar
7791 # only do something when no setting exists
7792 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7794 #include: debconf processing, question about foo and bar
7795 if [ "$RET" = "true" ] ; then
7796 dpkg-statoverride --update --add sysuser root 4755 $i
7801 The corresponding <tt>dpkg-statoverride --remove</tt>
7802 calls can then be made unconditionally when the package is
7810 <chapt id="customized-programs">
7811 <heading>Customized programs</heading>
7813 <sect id="arch-spec">
7814 <heading>Architecture specification strings</heading>
7817 If a program needs to specify an <em>architecture specification
7818 string</em> in some place, it should select one of the
7819 strings provided by <tt>dpkg-architecture -L</tt>. The
7820 strings are in the format
7821 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7822 is sometimes elided, as when the OS is Linux.<footnote>
7823 <p>Currently, the strings are:
7824 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7825 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7826 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7827 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7828 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7829 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7830 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7831 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7832 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7833 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7834 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7835 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7836 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7837 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7838 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7839 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7840 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7841 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7842 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7843 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7844 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7845 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7846 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7847 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7848 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7849 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7850 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7851 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7852 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7853 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7854 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7855 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7856 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7857 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7858 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7859 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7860 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7866 Note that we don't want to use
7867 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7868 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7869 since this would make our programs incompatible with other
7870 Linux distributions. We also don't use something like
7871 <tt><var>arch</var>-unknown-linux</tt>, since the
7872 <tt>unknown</tt> does not look very good.
7877 <heading>Daemons</heading>
7880 The configuration files <file>/etc/services</file>,
7881 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7882 by the <prgn>netbase</prgn> package and must not be modified
7887 If a package requires a new entry in one of these files, the
7888 maintainer should get in contact with the
7889 <prgn>netbase</prgn> maintainer, who will add the entries
7890 and release a new version of the <prgn>netbase</prgn>
7895 The configuration file <file>/etc/inetd.conf</file> must not be
7896 modified by the package's scripts except via the
7897 <prgn>update-inetd</prgn> script or the
7898 <file>DebianNet.pm</file> Perl module. See their documentation
7899 for details on how to add entries.
7903 If a package wants to install an example entry into
7904 <file>/etc/inetd.conf</file>, the entry must be preceded with
7905 exactly one hash character (<tt>#</tt>). Such lines are
7906 treated as "commented out by user" by the
7907 <prgn>update-inetd</prgn> script and are not changed or
7908 activated during package updates.
7913 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7917 Some programs need to create pseudo-ttys. This should be done
7918 using Unix98 ptys if the C library supports it. The resulting
7919 program must not be installed setuid root, unless that
7920 is required for other functionality.
7924 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7925 <file>/var/log/lastlog</file> must be installed writable by
7926 group <tt>utmp</tt>. Programs which need to modify those
7927 files must be installed setgid <tt>utmp</tt>.
7932 <heading>Editors and pagers</heading>
7935 Some programs have the ability to launch an editor or pager
7936 program to edit or display a text document. Since there are
7937 lots of different editors and pagers available in the Debian
7938 distribution, the system administrator and each user should
7939 have the possibility to choose their preferred editor and
7944 In addition, every program should choose a good default
7945 editor/pager if none is selected by the user or system
7950 Thus, every program that launches an editor or pager must
7951 use the EDITOR or PAGER environment variable to determine
7952 the editor or pager the user wishes to use. If these
7953 variables are not set, the programs <file>/usr/bin/editor</file>
7954 and <file>/usr/bin/pager</file> should be used, respectively.
7958 These two files are managed through the <prgn>dpkg</prgn>
7959 "alternatives" mechanism. Thus every package providing an
7960 editor or pager must call the
7961 <prgn>update-alternatives</prgn> script to register these
7966 If it is very hard to adapt a program to make use of the
7967 EDITOR or PAGER variables, that program may be configured to
7968 use <file>/usr/bin/sensible-editor</file> and
7969 <file>/usr/bin/sensible-pager</file> as the editor or pager
7970 program respectively. These are two scripts provided in the
7971 Debian base system that check the EDITOR and PAGER variables
7972 and launch the appropriate program, and fall back to
7973 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7974 variable is not set.
7978 A program may also use the VISUAL environment variable to
7979 determine the user's choice of editor. If it exists, it
7980 should take precedence over EDITOR. This is in fact what
7981 <file>/usr/bin/sensible-editor</file> does.
7985 It is not required for a package to depend on
7986 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7987 package to provide such virtual packages.<footnote>
7988 The Debian base system already provides an editor and a
7994 <sect id="web-appl">
7995 <heading>Web servers and applications</heading>
7998 This section describes the locations and URLs that should
7999 be used by all web servers and web applications in the
8006 Cgi-bin executable files are installed in the
8008 <example compact="compact">
8009 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8011 and should be referred to as
8012 <example compact="compact">
8013 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8019 <p>Access to HTML documents</p>
8022 HTML documents for a package are stored in
8023 <file>/usr/share/doc/<var>package</var></file>
8024 and can be referred to as
8025 <example compact="compact">
8026 http://localhost/doc/<var>package</var>/<var>filename</var>
8031 The web server should restrict access to the document
8032 tree so that only clients on the same host can read
8033 the documents. If the web server does not support such
8034 access controls, then it should not provide access at
8035 all, or ask about providing access during installation.
8040 <p>Access to images</p>
8042 It is recommended that images for a package be stored
8043 in <tt>/usr/share/images/<var>package</var></tt> and
8044 may be referred to through an alias <tt>/images/</tt>
8047 http://localhost/images/<package>/<filename>
8054 <p>Web Document Root</p>
8057 Web Applications should try to avoid storing files in
8058 the Web Document Root. Instead they should use the
8059 /usr/share/doc/<var>package</var> directory for
8060 documents and register the Web Application via the
8061 <package>doc-base</package> package. If access to the
8062 web document root is unavoidable then use
8063 <example compact="compact">
8066 as the Document Root. This might be just a symbolic
8067 link to the location where the system administrator
8068 has put the real document root.
8071 <item><p>Providing httpd and/or httpd-cgi</p>
8073 All web servers should provide the virtual package
8074 <tt>httpd</tt>. If a web server has CGI support it should
8075 provide <tt>httpd-cgi</tt> additionally.
8078 All web applications which do not contain CGI scripts should
8079 depend on <tt>httpd</tt>, all those web applications which
8080 <tt>do</tt> contain CGI scripts, should depend on
8088 <sect id="mail-transport-agents">
8089 <heading>Mail transport, delivery and user agents</heading>
8092 Debian packages which process electronic mail, whether mail
8093 user agents (MUAs) or mail transport agents (MTAs), must
8094 ensure that they are compatible with the configuration
8095 decisions below. Failure to do this may result in lost
8096 mail, broken <tt>From:</tt> lines, and other serious brain
8101 The mail spool is <file>/var/mail</file> and the interface to
8102 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8103 the FHS). On older systems, the mail spool may be
8104 physically located in <file>/var/spool/mail</file>, but all
8105 access to the mail spool should be via the
8106 <file>/var/mail</file> symlink. The mail spool is part of the
8107 base system and not part of the MTA package.
8111 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8112 programs (such as IMAP daemons) must lock the mailbox in an
8113 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8114 be combined with dot locking. To avoid deadlocks, a program
8115 should use <tt>fcntl()</tt> first and dot locking after
8116 this, or alternatively implement the two locking methods in
8117 a non blocking way<footnote>
8118 If it is not possible to establish both locks, the
8119 system shouldn't wait for the second lock to be
8120 established, but remove the first lock, wait a (random)
8121 time, and start over locking again.
8122 </footnote>. Using the functions <tt>maillock</tt> and
8123 <tt>mailunlock</tt> provided by the
8124 <tt>liblockfile*</tt><footnote>
8125 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8126 to use these functions.
8127 </footnote> packages is the recommended way to realize this.
8131 Mailboxes are generally either mode 600 and owned by
8132 <var>user</var> or mode 660 and owned by
8133 <tt><var>user</var>:mail</tt><footnote>
8134 There are two traditional permission schemes for mail spools:
8135 mode 600 with all mail delivery done by processes running as
8136 the destination user, or mode 660 and owned by group mail with
8137 mail delivery done by a process running as a system user in
8138 group mail. Historically, Debian required mode 660 mail
8139 spools to enable the latter model, but that model has become
8140 increasingly uncommon and the principle of least privilege
8141 indicates that mail systems that use the first model should
8142 use permissions of 600. If delivery to programs is permitted,
8143 it's easier to keep the mail system secure if the delivery
8144 agent runs as the destination user. Debian Policy therefore
8145 permits either scheme.
8146 </footnote>. The local system administrator may choose a
8147 different permission scheme; packages should not make
8148 assumptions about the permission and ownership of mailboxes
8149 unless required (such as when creating a new mailbox). A MUA
8150 may remove a mailbox (unless it has nonstandard permissions) in
8151 which case the MTA or another MUA must recreate it if needed.
8155 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8156 be setgid mail to do the locking mentioned above (and
8157 must obviously avoid accessing other users' mailboxes
8158 using this privilege).</p>
8161 <file>/etc/aliases</file> is the source file for the system mail
8162 aliases (e.g., postmaster, usenet, etc.), it is the one
8163 which the sysadmin and <prgn>postinst</prgn> scripts may
8164 edit. After <file>/etc/aliases</file> is edited the program or
8165 human editing it must call <prgn>newaliases</prgn>. All MTA
8166 packages must come with a <prgn>newaliases</prgn> program,
8167 even if it does nothing, but older MTA packages did not do
8168 this so programs should not fail if <prgn>newaliases</prgn>
8169 cannot be found. Note that because of this, all MTA
8170 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8171 <tt>Replaces: mail-transport-agent</tt> control file
8176 The convention of writing <tt>forward to
8177 <var>address</var></tt> in the mailbox itself is not
8178 supported. Use a <tt>.forward</tt> file instead.</p>
8181 The <prgn>rmail</prgn> program used by UUCP
8182 for incoming mail should be <file>/usr/sbin/rmail</file>.
8183 Likewise, <prgn>rsmtp</prgn>, for receiving
8184 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8188 If your package needs to know what hostname to use on (for
8189 example) outgoing news and mail messages which are generated
8190 locally, you should use the file <file>/etc/mailname</file>. It
8191 will contain the portion after the username and <tt>@</tt>
8192 (at) sign for email addresses of users on the machine
8193 (followed by a newline).
8197 Such a package should check for the existence of this file
8198 when it is being configured. If it exists, it should be
8199 used without comment, although an MTA's configuration script
8200 may wish to prompt the user even if it finds that this file
8201 exists. If the file does not exist, the package should
8202 prompt the user for the value (preferably using
8203 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8204 as well as using it in the package's configuration. The
8205 prompt should make it clear that the name will not just be
8206 used by that package. For example, in this situation the
8207 <tt>inn</tt> package could say something like:
8208 <example compact="compact">
8209 Please enter the "mail name" of your system. This is the
8210 hostname portion of the address to be shown on outgoing
8211 news and mail messages. The default is
8212 <var>syshostname</var>, your system's host name. Mail
8213 name ["<var>syshostname</var>"]:
8215 where <var>syshostname</var> is the output of <tt>hostname
8221 <heading>News system configuration</heading>
8224 All the configuration files related to the NNTP (news)
8225 servers and clients should be located under
8226 <file>/etc/news</file>.</p>
8229 There are some configuration issues that apply to a number
8230 of news clients and server packages on the machine. These
8234 <tag><file>/etc/news/organization</file></tag>
8236 A string which should appear as the
8237 organization header for all messages posted
8238 by NNTP clients on the machine
8241 <tag><file>/etc/news/server</file></tag>
8243 Contains the FQDN of the upstream NNTP
8244 server, or localhost if the local machine is
8249 Other global files may be added as required for cross-package news
8256 <heading>Programs for the X Window System</heading>
8259 <heading>Providing X support and package priorities</heading>
8262 Programs that can be configured with support for the X
8263 Window System must be configured to do so and must declare
8264 any package dependencies necessary to satisfy their
8265 runtime requirements when using the X Window System. If
8266 such a package is of higher priority than the X packages
8267 on which it depends, it is required that either the
8268 X-specific components be split into a separate package, or
8269 that an alternative version of the package, which includes
8270 X support, be provided, or that the package's priority be
8276 <heading>Packages providing an X server</heading>
8279 Packages that provide an X server that, directly or
8280 indirectly, communicates with real input and display
8281 hardware should declare in their control data that they
8282 provide the virtual package <tt>xserver</tt>.<footnote>
8283 This implements current practice, and provides an
8284 actual policy for usage of the <tt>xserver</tt>
8285 virtual package which appears in the virtual packages
8286 list. In a nutshell, X servers that interface
8287 directly with the display and input hardware or via
8288 another subsystem (e.g., GGI) should provide
8289 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8290 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8296 <heading>Packages providing a terminal emulator</heading>
8299 Packages that provide a terminal emulator for the X Window
8300 System which meet the criteria listed below should declare
8301 in their control data that they provide the virtual
8302 package <tt>x-terminal-emulator</tt>. They should also
8303 register themselves as an alternative for
8304 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8309 To be an <tt>x-terminal-emulator</tt>, a program must:
8310 <list compact="compact">
8312 Be able to emulate a DEC VT100 terminal, or a
8313 compatible terminal.
8317 Support the command-line option <tt>-e
8318 <var>command</var></tt>, which creates a new
8319 terminal window<footnote>
8320 "New terminal window" does not necessarily mean
8321 a new top-level X window directly parented by
8322 the window manager; it could, if the terminal
8323 emulator application were so coded, be a new
8324 "view" in a multiple-document interface (MDI).
8326 and runs the specified <var>command</var>,
8327 interpreting the entirety of the rest of the command
8328 line as a command to pass straight to exec, in the
8329 manner that <tt>xterm</tt> does.
8333 Support the command-line option <tt>-T
8334 <var>title</var></tt>, which creates a new terminal
8335 window with the window title <var>title</var>.
8342 <heading>Packages providing a window manager</heading>
8345 Packages that provide a window manager should declare in
8346 their control data that they provide the virtual package
8347 <tt>x-window-manager</tt>. They should also register
8348 themselves as an alternative for
8349 <file>/usr/bin/x-window-manager</file>, with a priority
8350 calculated as follows:
8351 <list compact="compact">
8353 Start with a priority of 20.
8357 If the window manager supports the Debian menu
8358 system, add 20 points if this support is available
8359 in the package's default configuration (i.e., no
8360 configuration files belonging to the system or user
8361 have to be edited to activate the feature); if
8362 configuration files must be modified, add only 10
8368 If the window manager complies with <url
8369 id="http://www.freedesktop.org/Standards/wm-spec"
8370 name="The Window Manager Specification Project">,
8371 written by the <url id="http://www.freedesktop.org/"
8372 name="Free Desktop Group">, add 40 points.
8376 If the window manager permits the X session to be
8377 restarted using a <em>different</em> window manager
8378 (without killing the X server) in its default
8379 configuration, add 10 points; otherwise add none.
8386 <heading>Packages providing fonts</heading>
8389 Packages that provide fonts for the X Window
8391 For the purposes of Debian Policy, a "font for the X
8392 Window System" is one which is accessed via X protocol
8393 requests. Fonts for the Linux console, for PostScript
8394 renderer, or any other purpose, do not fit this
8395 definition. Any tool which makes such fonts available
8396 to the X Window System, however, must abide by this
8399 must do a number of things to ensure that they are both
8400 available without modification of the X or font server
8401 configuration, and that they do not corrupt files used by
8402 other font packages to register information about
8406 Fonts of any type supported by the X Window System
8407 must be in a separate binary package from any
8408 executables, libraries, or documentation (except
8409 that specific to the fonts shipped, such as their
8410 license information). If one or more of the fonts
8411 so packaged are necessary for proper operation of
8412 the package with which they are associated the font
8413 package may be Recommended; if the fonts merely
8414 provide an enhancement, a Suggests relationship may
8415 be used. Packages must not Depend on font
8417 This is because the X server may retrieve fonts
8418 from the local file system or over the network
8419 from an X font server; the Debian package system
8420 is empowered to deal only with the local
8426 BDF fonts must be converted to PCF fonts with the
8427 <prgn>bdftopcf</prgn> utility (available in the
8428 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8429 placed in a directory that corresponds to their
8431 <list compact="compact">
8433 100 dpi fonts must be placed in
8434 <file>/usr/share/fonts/X11/100dpi/</file>.
8438 75 dpi fonts must be placed in
8439 <file>/usr/share/fonts/X11/75dpi/</file>.
8443 Character-cell fonts, cursor fonts, and other
8444 low-resolution fonts must be placed in
8445 <file>/usr/share/fonts/X11/misc/</file>.
8451 Type 1 fonts must be placed in
8452 <file>/usr/share/fonts/X11/Type1/</file>. If font
8453 metric files are available, they must be placed here
8458 Subdirectories of <file>/usr/share/fonts/X11/</file>
8459 other than those listed above must be neither
8460 created nor used. (The <file>PEX</file>, <file>CID</file>,
8461 <file>Speedo</file>, and <file>cyrillic</file> directories
8462 are excepted for historical reasons, but installation of
8463 files into these directories remains discouraged.)
8467 Font packages may, instead of placing files directly
8468 in the X font directories listed above, provide
8469 symbolic links in that font directory pointing to
8470 the files' actual location in the filesystem. Such
8471 a location must comply with the FHS.
8475 Font packages should not contain both 75dpi and
8476 100dpi versions of a font. If both are available,
8477 they should be provided in separate binary packages
8478 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8479 the names of the packages containing the
8480 corresponding fonts.
8484 Fonts destined for the <file>misc</file> subdirectory
8485 should not be included in the same package as 75dpi
8486 or 100dpi fonts; instead, they should be provided in
8487 a separate package with <tt>-misc</tt> appended to
8492 Font packages must not provide the files
8493 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8494 <file>fonts.scale</file> in a font directory:
8497 <file>fonts.dir</file> files must not be provided at all.
8501 <file>fonts.alias</file> and <file>fonts.scale</file>
8502 files, if needed, should be provided in the
8504 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8505 where <var>fontdir</var> is the name of the
8507 <file>/usr/share/fonts/X11/</file> where the
8508 package's corresponding fonts are stored
8509 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8510 <var>package</var> is the name of the package
8511 that provides these fonts, and
8512 <var>extension</var> is either <tt>scale</tt>
8513 or <tt>alias</tt>, whichever corresponds to
8520 Font packages must declare a dependency on
8521 <tt>xfonts-utils</tt> in their control
8526 Font packages that provide one or more
8527 <file>fonts.scale</file> files as described above must
8528 invoke <prgn>update-fonts-scale</prgn> on each
8529 directory into which they installed fonts
8530 <em>before</em> invoking
8531 <prgn>update-fonts-dir</prgn> on that directory.
8532 This invocation must occur in both the
8533 <prgn>postinst</prgn> (for all arguments) and
8534 <prgn>postrm</prgn> (for all arguments except
8535 <tt>upgrade</tt>) scripts.
8539 Font packages that provide one or more
8540 <file>fonts.alias</file> files as described above must
8541 invoke <prgn>update-fonts-alias</prgn> on each
8542 directory into which they installed fonts. This
8543 invocation must occur in both the
8544 <prgn>postinst</prgn> (for all arguments) and
8545 <prgn>postrm</prgn> (for all arguments except
8546 <tt>upgrade</tt>) scripts.
8550 Font packages must invoke
8551 <prgn>update-fonts-dir</prgn> on each directory into
8552 which they installed fonts. This invocation must
8553 occur in both the <prgn>postinst</prgn> (for all
8554 arguments) and <prgn>postrm</prgn> (for all
8555 arguments except <tt>upgrade</tt>) scripts.
8559 Font packages must not provide alias names for the
8560 fonts they include which collide with alias names
8561 already in use by fonts already packaged.
8565 Font packages must not provide fonts with the same
8566 XLFD registry name as another font already packaged.
8573 <heading>Application defaults files</heading>
8576 Application defaults files must be installed in the
8577 directory <file>/etc/X11/app-defaults/</file> (use of a
8578 localized subdirectory of <file>/etc/X11/</file> as described
8579 in the <em>X Toolkit Intrinsics - C Language
8580 Interface</em> manual is also permitted). They must be
8581 registered as <tt>conffile</tt>s or handled as
8582 configuration files.
8586 Customization of programs' X resources may also be
8587 supported with the provision of a file with the same name
8588 as that of the package placed in the
8589 <file>/etc/X11/Xresources/</file> directory, which must
8590 registered as a <tt>conffile</tt> or handled as a
8591 configuration file.<footnote>
8592 Note that this mechanism is not the same as using
8593 app-defaults; app-defaults are tied to the client
8594 binary on the local file system, whereas X resources
8595 are stored in the X server and affect all connecting
8602 <heading>Installation directory issues</heading>
8605 Packages using the X Window System should not be
8606 configured to install files under the
8607 <file>/usr/X11R6/</file> directory. The
8608 <file>/usr/X11R6/</file> directory hierarchy should be
8609 regarded as obsolete.
8613 Programs that use GNU <prgn>autoconf</prgn> and
8614 <prgn>automake</prgn> are usually easily configured at
8615 compile time to use <file>/usr/</file> instead of
8616 <file>/usr/X11R6/</file>, and this should be done whenever
8617 possible. Configuration files for window managers and
8618 display managers should be placed in a subdirectory of
8619 <file>/etc/X11/</file> corresponding to the package name due
8620 to these programs' tight integration with the mechanisms
8621 of the X Window System. Application-level programs should
8622 use the <file>/etc/</file> directory unless otherwise mandated
8627 The installation of files into subdirectories
8628 of <file>/usr/X11R6/include/X11/</file> and
8629 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8630 package maintainers should determine if subdirectories of
8631 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8636 Packages should install any relevant files into the
8637 directories <file>/usr/include/X11/</file> and
8638 <file>/usr/lib/X11/</file>, but if they do so, they must
8639 pre-depend on <tt>x11-common (>=
8640 1:7.0.0)</tt><footnote>
8642 These libraries used to be all symbolic
8643 links. However, with <tt>X11R7</tt>,
8644 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8645 are now real directories, and packages
8646 <strong>should</strong> ship their files here instead
8647 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8648 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8649 responsible for converting these symlinks into
8657 <heading>The OSF/Motif and OpenMotif libraries</heading>
8660 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8661 OpenMotif libraries</em><footnote>
8662 OSF/Motif and OpenMotif are collectively referred to as
8663 "Motif" in this policy document.
8665 should be compiled against and tested with LessTif (a free
8666 re-implementation of Motif) instead. If the maintainer
8667 judges that the program or programs do not work
8668 sufficiently well with LessTif to be distributed and
8669 supported, but do so when compiled against Motif, then two
8670 versions of the package should be created; one linked
8671 statically against Motif and with <tt>-smotif</tt>
8672 appended to the package name, and one linked dynamically
8673 against Motif and with <tt>-dmotif</tt> appended to the
8678 Both Motif-linked versions are dependent
8679 upon non-DFSG-compliant software and thus cannot be
8680 uploaded to the <em>main</em> distribution; if the
8681 software is itself DFSG-compliant it may be uploaded to
8682 the <em>contrib</em> distribution. While known existing
8683 versions of Motif permit unlimited redistribution of
8684 binaries linked against the library (whether statically or
8685 dynamically), it is the package maintainer's
8686 responsibility to determine whether this is permitted by
8687 the license of the copy of Motif in their possession.
8693 <heading>Perl programs and modules</heading>
8696 Perl programs and modules should follow the current Perl policy.
8700 The Perl policy can be found in the <tt>perl-policy</tt>
8701 files in the <tt>debian-policy</tt> package.
8702 It is also available from the Debian web mirrors at
8703 <tt><url name="/doc/packaging-manuals/perl-policy/"
8704 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8709 <heading>Emacs lisp programs</heading>
8712 Please refer to the "Debian Emacs Policy" for details of how to
8713 package emacs lisp programs.
8717 The Emacs policy is available in
8718 <file>debian-emacs-policy.gz</file> of the
8719 <package>emacsen-common</package> package.
8720 It is also available from the Debian web mirrors at
8721 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8722 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8727 <heading>Games</heading>
8730 The permissions on <file>/var/games</file> are mode 755, owner
8731 <tt>root</tt> and group <tt>root</tt>.
8735 Each game decides on its own security policy.</p>
8738 Games which require protected, privileged access to
8739 high-score files, saved games, etc., may be made
8740 set-<em>group</em>-id (mode 2755) and owned by
8741 <tt>root:games</tt>, and use files and directories with
8742 appropriate permissions (770 <tt>root:games</tt>, for
8743 example). They must not be made
8744 set-<em>user</em>-id, as this causes security problems. (If
8745 an attacker can subvert any set-user-id game they can
8746 overwrite the executable of any other, causing other players
8747 of these games to run a Trojan horse program. With a
8748 set-group-id game the attacker only gets access to less
8749 important game data, and if they can get at the other
8750 players' accounts at all it will take considerably more
8754 Some packages, for example some fortune cookie programs, are
8755 configured by the upstream authors to install with their
8756 data files or other static information made unreadable so
8757 that they can only be accessed through set-id programs
8758 provided. You should not do this in a Debian package: anyone can
8759 download the <file>.deb</file> file and read the data from it,
8760 so there is no point making the files unreadable. Not
8761 making the files unreadable also means that you don't have
8762 to make so many programs set-id, which reduces the risk of a
8766 As described in the FHS, binaries of games should be
8767 installed in the directory <file>/usr/games</file>. This also
8768 applies to games that use the X Window System. Manual pages
8769 for games (X and non-X games) should be installed in
8770 <file>/usr/share/man/man6</file>.</p>
8776 <heading>Documentation</heading>
8779 <heading>Manual pages</heading>
8782 You should install manual pages in <prgn>nroff</prgn> source
8783 form, in appropriate places under <file>/usr/share/man</file>.
8784 You should only use sections 1 to 9 (see the FHS for more
8785 details). You must not install a pre-formatted "cat page".
8789 Each program, utility, and function should have an
8790 associated manual page included in the same package. It is
8791 suggested that all configuration files also have a manual
8792 page included as well. Manual pages for protocols and other
8793 auxiliary things are optional.
8797 If no manual page is available, this is considered as a bug
8798 and should be reported to the Debian Bug Tracking System (the
8799 maintainer of the package is allowed to write this bug report
8800 themselves, if they so desire). Do not close the bug report
8801 until a proper man page is available.<footnote>
8802 It is not very hard to write a man page. See the
8803 <url id="http://www.schweikhardt.net/man_page_howto.html"
8804 name="Man-Page-HOWTO">,
8805 <manref name="man" section="7">, the examples
8806 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8807 the helper programs <prgn>help2man</prgn>, or the
8808 directory <file>/usr/share/doc/man-db/examples</file>.
8813 You may forward a complaint about a missing man page to the
8814 upstream authors, and mark the bug as forwarded in the
8815 Debian bug tracking system. Even though the GNU Project do
8816 not in general consider the lack of a man page to be a bug,
8817 we do; if they tell you that they don't consider it a bug
8818 you should leave the bug in our bug tracking system open
8823 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8827 If one man page needs to be accessible via several names it
8828 is better to use a symbolic link than the <file>.so</file>
8829 feature, but there is no need to fiddle with the relevant
8830 parts of the upstream source to change from <file>.so</file> to
8831 symlinks: don't do it unless it's easy. You should not
8832 create hard links in the manual page directories, nor put
8833 absolute filenames in <file>.so</file> directives. The filename
8834 in a <file>.so</file> in a man page should be relative to the
8835 base of the man page tree (usually
8836 <file>/usr/share/man</file>). If you do not create any links
8837 (whether symlinks, hard links, or <tt>.so</tt> directives)
8838 in the file system to the alternate names of the man page,
8839 then you should not rely on <prgn>man</prgn> finding your
8840 man page under those names based solely on the information in
8841 the man page's header.<footnote>
8842 Supporting this in <prgn>man</prgn> often requires
8843 unreasonable processing time to find a manual page or to
8844 report that none exists, and moves knowledge into man's
8845 database that would be better left in the file system.
8846 This support is therefore deprecated and will cease to
8847 be present in the future.
8852 Manual pages in locale-specific subdirectories of
8853 <file>/usr/share/man</file> should use either UTF-8 or the usual
8854 legacy encoding for that language (normally the one corresponding
8855 to the shortest relevant locale name in
8856 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8857 <file>/usr/share/man/fr</file> should use either UTF-8 or
8858 ISO-8859-1.<footnote>
8859 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8860 use. In future, all manual pages will be required to use
8866 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8867 included in the subdirectory name unless it indicates a
8868 significant difference in the language, as this excludes
8869 speakers of the language in other countries.<footnote>
8870 At the time of writing, Chinese and Portuguese are the main
8871 languages with such differences, so <file>pt_BR</file>,
8872 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8877 Due to limitations in current implementations, all characters
8878 in the manual page source should be representable in the usual
8879 legacy encoding for that language, even if the file is
8880 actually encoded in UTF-8. Safe alternative ways to write many
8881 characters outside that range may be found in
8882 <manref name="groff_char" section="7">.
8887 <heading>Info documents</heading>
8890 Info documents should be installed in <file>/usr/share/info</file>.
8891 They should be compressed with <tt>gzip -9</tt>.
8895 Your package should call <prgn>install-info</prgn> to update
8896 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8897 script when called with a <tt>configure</tt> argument, for
8899 <example compact="compact">
8900 install-info --quiet --section Development Development \
8901 /usr/share/info/foobar.info
8905 It is a good idea to specify a section for the location of
8906 your program; this is done with the <tt>--section</tt>
8907 switch. To determine which section to use, you should look
8908 at <file>/usr/share/info/dir</file> on your system and choose the most
8909 relevant (or create a new section if none of the current
8910 sections are relevant). Note that the <tt>--section</tt>
8911 flag takes two arguments; the first is a regular expression
8912 to match (case-insensitively) against an existing section,
8913 the second is used when creating a new one.</p>
8916 You should remove the entries in the <prgn>prerm</prgn>
8917 script when called with a <tt>remove</tt> argument:
8918 <example compact="compact">
8919 install-info --quiet --remove /usr/share/info/foobar.info
8923 If <prgn>install-info</prgn> cannot find a description entry
8924 in the Info file you must supply one. See <manref
8925 name="install-info" section="8"> for details.</p>
8929 <heading>Additional documentation</heading>
8932 Any additional documentation that comes with the package may
8933 be installed at the discretion of the package maintainer.
8934 Plain text documentation should be installed in the directory
8935 <file>/usr/share/doc/<var>package</var></file>, where
8936 <var>package</var> is the name of the package, and
8937 compressed with <tt>gzip -9</tt> unless it is small.
8941 If a package comes with large amounts of documentation which
8942 many users of the package will not require you should create
8943 a separate binary package to contain it, so that it does not
8944 take up disk space on the machines of users who do not need
8945 or want it installed.</p>
8948 It is often a good idea to put text information files
8949 (<file>README</file>s, changelogs, and so forth) that come with
8950 the source package in <file>/usr/share/doc/<var>package</var></file>
8951 in the binary package. However, you don't need to install
8952 the instructions for building and installing the package, of
8956 Packages must not require the existence of any files in
8957 <file>/usr/share/doc/</file> in order to function
8959 The system administrator should be able to
8960 delete files in <file>/usr/share/doc/</file> without causing
8961 any programs to break.
8963 Any files that are referenced by programs but are also
8964 useful as stand alone documentation should be installed under
8965 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8966 <file>/usr/share/doc/<var>package</var></file>.
8970 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8971 link to another directory in <file>/usr/share/doc</file> only if
8972 the two packages both come from the same source and the
8973 first package Depends on the second.<footnote>
8975 Please note that this does not override the section on
8976 changelog files below, so the file
8977 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8978 must refer to the changelog for the current version of
8979 <var>package</var> in question. In practice, this means
8980 that the sources of the target and the destination of the
8981 symlink must be the same (same source package and
8988 Former Debian releases placed all additional documentation
8989 in <file>/usr/doc/<var>package</var></file>. This has been
8990 changed to <file>/usr/share/doc/<var>package</var></file>,
8991 and packages must not put documentation in the directory
8992 <file>/usr/doc/<var>package</var></file>. <footnote>
8993 At this phase of the transition, we no longer require a
8994 symbolic link in <file>/usr/doc/</file>. At a later point,
8995 policy shall change to make the symbolic links a bug.
9001 <heading>Preferred documentation formats</heading>
9004 The unification of Debian documentation is being carried out
9008 If your package comes with extensive documentation in a
9009 markup format that can be converted to various other formats
9010 you should if possible ship HTML versions in a binary
9011 package, in the directory
9012 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9013 its subdirectories.<footnote>
9014 The rationale: The important thing here is that HTML
9015 docs should be available in <em>some</em> package, not
9016 necessarily in the main binary package.
9021 Other formats such as PostScript may be provided at the
9022 package maintainer's discretion.
9026 <sect id="copyrightfile">
9027 <heading>Copyright information</heading>
9030 Every package must be accompanied by a verbatim copy of its
9031 copyright and distribution license in the file
9032 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9033 file must neither be compressed nor be a symbolic link.
9037 In addition, the copyright file must say where the upstream
9038 sources (if any) were obtained. It should name the original
9039 authors of the package and the Debian maintainer(s) who were
9040 involved with its creation.
9044 Packages in the <em>contrib</em> or <em>non-free</em> archive
9045 areas should state in the copyright file that the package is not
9046 part of the Debian GNU/Linux distribution and briefly explain
9051 A copy of the file which will be installed in
9052 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9053 be in <file>debian/copyright</file> in the source package.
9057 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9058 link to another directory in <file>/usr/share/doc</file> only if
9059 the two packages both come from the same source and the
9060 first package Depends on the second. These rules are
9061 important because copyrights must be extractable by
9066 Packages distributed under the UCB BSD license, the Apache
9067 license (version 2.0), the Artistic license, the GNU GPL
9068 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9069 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9070 files under <file>/usr/share/common-licenses</file>,<footnote>
9073 <file>/usr/share/common-licenses/BSD</file>,
9074 <file>/usr/share/common-licenses/Apache-2.0</file>,
9075 <file>/usr/share/common-licenses/Artistic</file>,
9076 <file>/usr/share/common-licenses/GPL-2</file>,
9077 <file>/usr/share/common-licenses/GPL-3</file>,
9078 <file>/usr/share/common-licenses/LGPL-2</file>,
9079 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9080 <file>/usr/share/common-licenses/LGPL-3</file>,
9081 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9082 <file>/usr/share/common-licenses/GFDL-1.3</file>
9085 </footnote> rather than quoting them in the copyright
9090 You should not use the copyright file as a general <file>README</file>
9091 file. If your package has such a file it should be
9092 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9093 <file>README.Debian</file> or some other appropriate place.</p>
9097 <heading>Examples</heading>
9100 Any examples (configurations, source files, whatever),
9101 should be installed in a directory
9102 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9103 files should not be referenced by any program: they're there
9104 for the benefit of the system administrator and users as
9105 documentation only. Architecture-specific example files
9106 should be installed in a directory
9107 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9109 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9110 latter directory itself may be a symbolic link to the
9115 If the purpose of a package is to provide examples, then the
9116 example files may be installed into
9117 <file>/usr/share/doc/<var>package</var></file>.
9121 <sect id="changelogs">
9122 <heading>Changelog files</heading>
9125 Packages that are not Debian-native must contain a
9126 compressed copy of the <file>debian/changelog</file> file from
9127 the Debian source tree in
9128 <file>/usr/share/doc/<var>package</var></file> with the name
9129 <file>changelog.Debian.gz</file>.
9133 If an upstream changelog is available, it should be accessible as
9134 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9135 plain text. If the upstream changelog is distributed in
9136 HTML, it should be made available in that form as
9137 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9138 and a plain text <file>changelog.gz</file> should be generated
9139 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9140 the upstream changelog files do not already conform to this
9141 naming convention, then this may be achieved either by
9142 renaming the files, or by adding a symbolic link, at the
9143 maintainer's discretion.<footnote>
9144 Rationale: People should not have to look in places for
9145 upstream changelogs merely because they are given
9146 different names or are distributed in HTML format.
9151 All of these files should be installed compressed using
9152 <tt>gzip -9</tt>, as they will become large with time even
9153 if they start out small.
9157 If the package has only one changelog which is used both as
9158 the Debian changelog and the upstream one because there is
9159 no separate upstream maintainer then that changelog should
9160 usually be installed as
9161 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9162 there is a separate upstream maintainer, but no upstream
9163 changelog, then the Debian changelog should still be called
9164 <file>changelog.Debian.gz</file>.
9168 For details about the format and contents of the Debian
9169 changelog file, please see <ref id="dpkgchangelog">.
9174 <appendix id="pkg-scope">
9175 <heading>Introduction and scope of these appendices</heading>
9178 These appendices are taken essentially verbatim from the
9179 now-deprecated Packaging Manual, version 3.2.1.0. They are
9180 the chapters which are likely to be of use to package
9181 maintainers and which have not already been included in the
9182 policy document itself. Most of these sections are very likely
9183 not relevant to policy; they should be treated as
9184 documentation for the packaging system. Please note that these
9185 appendices are included for convenience, and for historical
9186 reasons: they used to be part of policy package, and they have
9187 not yet been incorporated into dpkg documentation. However,
9188 they still have value, and hence they are presented here.
9192 They have not yet been checked to ensure that they are
9193 compatible with the contents of policy, and if there are any
9194 contradictions, the version in the main policy document takes
9195 precedence. The remaining chapters of the old Packaging
9196 Manual have also not been read in detail to ensure that there
9197 are not parts which have been left out. Both of these will be
9202 Certain parts of the Packaging manual were integrated into the
9203 Policy Manual proper, and removed from the appendices. Links
9204 have been placed from the old locations to the new ones.
9208 <prgn>dpkg</prgn> is a suite of programs for creating binary
9209 package files and installing and removing them on Unix
9211 <prgn>dpkg</prgn> is targeted primarily at Debian
9212 GNU/Linux, but may work on or be ported to other
9218 The binary packages are designed for the management of
9219 installed executable programs (usually compiled binaries) and
9220 their associated data, though source code examples and
9221 documentation are provided as part of some packages.</p>
9224 This manual describes the technical aspects of creating Debian
9225 binary packages (<file>.deb</file> files). It documents the
9226 behavior of the package management programs
9227 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9228 they interact with packages.</p>
9231 It also documents the interaction between
9232 <prgn>dselect</prgn>'s core and the access method scripts it
9233 uses to actually install the selected packages, and describes
9234 how to create a new access method.</p>
9237 This manual does not go into detail about the options and
9238 usage of the package building and installation tools. It
9239 should therefore be read in conjunction with those programs'
9244 The utility programs which are provided with <prgn>dpkg</prgn>
9245 for managing various system configuration and similar issues,
9246 such as <prgn>update-rc.d</prgn> and
9247 <prgn>install-info</prgn>, are not described in detail here -
9248 please see their man pages.
9252 It is assumed that the reader is reasonably familiar with the
9253 <prgn>dpkg</prgn> System Administrators' manual.
9254 Unfortunately this manual does not yet exist.
9258 The Debian version of the FSF's GNU hello program is provided
9259 as an example for people wishing to create Debian
9260 packages. The Debian <prgn>debmake</prgn> package is
9261 recommended as a very helpful tool in creating and maintaining
9262 Debian packages. However, while the tools and examples are
9263 helpful, they do not replace the need to read and follow the
9264 Policy and Programmer's Manual.</p>
9267 <appendix id="pkg-binarypkg">
9268 <heading>Binary packages (from old Packaging Manual)</heading>
9271 The binary package has two main sections. The first part
9272 consists of various control information files and scripts used
9273 by <prgn>dpkg</prgn> when installing and removing. See <ref
9274 id="pkg-controlarea">.
9278 The second part is an archive containing the files and
9279 directories to be installed.
9283 In the future binary packages may also contain other
9284 components, such as checksums and digital signatures. The
9285 format for the archive is described in full in the
9286 <file>deb(5)</file> man page.
9290 <sect id="pkg-bincreating"><heading>Creating package files -
9291 <prgn>dpkg-deb</prgn>
9295 All manipulation of binary package files is done by
9296 <prgn>dpkg-deb</prgn>; it's the only program that has
9297 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9298 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9299 will spot that the options requested are appropriate to
9300 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9305 In order to create a binary package you must make a
9306 directory tree which contains all the files and directories
9307 you want to have in the file system data part of the package.
9308 In Debian-format source packages this directory is usually
9309 <file>debian/tmp</file>, relative to the top of the package's
9314 They should have the locations (relative to the root of the
9315 directory tree you're constructing) ownerships and
9316 permissions which you want them to have on the system when
9321 With current versions of <prgn>dpkg</prgn> the uid/username
9322 and gid/groupname mappings for the users and groups being
9323 used should be the same on the system where the package is
9324 built and the one where it is installed.
9328 You need to add one special directory to the root of the
9329 miniature file system tree you're creating:
9330 <prgn>DEBIAN</prgn>. It should contain the control
9331 information files, notably the binary package control file
9332 (see <ref id="pkg-controlfile">).
9336 The <prgn>DEBIAN</prgn> directory will not appear in the
9337 file system archive of the package, and so won't be installed
9338 by <prgn>dpkg</prgn> when the package is installed.
9342 When you've prepared the package, you should invoke:
9344 dpkg --build <var>directory</var>
9349 This will build the package in
9350 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9351 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9352 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9357 See the man page <manref name="dpkg-deb" section="8"> for details of how
9358 to examine the contents of this newly-created file. You may find the
9359 output of following commands enlightening:
9361 dpkg-deb --info <var>filename</var>.deb
9362 dpkg-deb --contents <var>filename</var>.deb
9363 dpkg --contents <var>filename</var>.deb
9365 To view the copyright file for a package you could use this command:
9367 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9372 <sect id="pkg-controlarea">
9373 <heading>Package control information files</heading>
9376 The control information portion of a binary package is a
9377 collection of files with names known to <prgn>dpkg</prgn>.
9378 It will treat the contents of these files specially - some
9379 of them contain information used by <prgn>dpkg</prgn> when
9380 installing or removing the package; others are scripts which
9381 the package maintainer wants <prgn>dpkg</prgn> to run.
9385 It is possible to put other files in the package control
9386 area, but this is not generally a good idea (though they
9387 will largely be ignored).
9391 Here is a brief list of the control info files supported by
9392 <prgn>dpkg</prgn> and a summary of what they're used for.
9397 <tag><tt>control</tt>
9400 This is the key description file used by
9401 <prgn>dpkg</prgn>. It specifies the package's name
9402 and version, gives its description for the user,
9403 states its relationships with other packages, and so
9404 forth. See <ref id="sourcecontrolfiles"> and
9405 <ref id="binarycontrolfiles">.
9409 It is usually generated automatically from information
9410 in the source package by the
9411 <prgn>dpkg-gencontrol</prgn> program, and with
9412 assistance from <prgn>dpkg-shlibdeps</prgn>.
9413 See <ref id="pkg-sourcetools">.
9417 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9422 These are executable files (usually scripts) which
9423 <prgn>dpkg</prgn> runs during installation, upgrade
9424 and removal of packages. They allow the package to
9425 deal with matters which are particular to that package
9426 or require more complicated processing than that
9427 provided by <prgn>dpkg</prgn>. Details of when and
9428 how they are called are in <ref id="maintainerscripts">.
9432 It is very important to make these scripts idempotent.
9433 See <ref id="idempotency">.
9437 The maintainer scripts are guaranteed to run with a
9438 controlling terminal and can interact with the user.
9439 See <ref id="controllingterminal">.
9443 <tag><tt>conffiles</tt>
9446 This file contains a list of configuration files which
9447 are to be handled automatically by <prgn>dpkg</prgn>
9448 (see <ref id="pkg-conffiles">). Note that not necessarily
9449 every configuration file should be listed here.
9452 <tag><tt>shlibs</tt>
9455 This file contains a list of the shared libraries
9456 supplied by the package, with dependency details for
9457 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9458 when it determines what dependencies are required in a
9459 package control file. The <tt>shlibs</tt> file format
9460 is described on <ref id="shlibs">.
9465 <sect id="pkg-controlfile">
9466 <heading>The main control information file: <tt>control</tt></heading>
9469 The most important control information file used by
9470 <prgn>dpkg</prgn> when it installs a package is
9471 <tt>control</tt>. It contains all the package's "vital
9476 The binary package control files of packages built from
9477 Debian sources are made by a special tool,
9478 <prgn>dpkg-gencontrol</prgn>, which reads
9479 <file>debian/control</file> and <file>debian/changelog</file> to
9480 find the information it needs. See <ref id="pkg-sourcepkg"> for
9485 The fields in binary package control files are listed in
9486 <ref id="binarycontrolfiles">.
9490 A description of the syntax of control files and the purpose
9491 of the fields is available in <ref id="controlfields">.
9496 <heading>Time Stamps</heading>
9499 See <ref id="timestamps">.
9504 <appendix id="pkg-sourcepkg">
9505 <heading>Source packages (from old Packaging Manual) </heading>
9508 The Debian binary packages in the distribution are generated
9509 from Debian sources, which are in a special format to assist
9510 the easy and automatic building of binaries.
9513 <sect id="pkg-sourcetools">
9514 <heading>Tools for processing source packages</heading>
9517 Various tools are provided for manipulating source packages;
9518 they pack and unpack sources and help build of binary
9519 packages and help manage the distribution of new versions.
9523 They are introduced and typical uses described here; see
9524 <manref name="dpkg-source" section="1"> for full
9525 documentation about their arguments and operation.
9529 For examples of how to construct a Debian source package,
9530 and how to use those utilities that are used by Debian
9531 source packages, please see the <prgn>hello</prgn> example
9535 <sect1 id="pkg-dpkg-source">
9537 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9542 This program is frequently used by hand, and is also
9543 called from package-independent automated building scripts
9544 such as <prgn>dpkg-buildpackage</prgn>.
9548 To unpack a package it is typically invoked with
9550 dpkg-source -x <var>.../path/to/filename</var>.dsc
9555 with the <file><var>filename</var>.tar.gz</file> and
9556 <file><var>filename</var>.diff.gz</file> (if applicable) in
9557 the same directory. It unpacks into
9558 <file><var>package</var>-<var>version</var></file>, and if
9560 <file><var>package</var>-<var>version</var>.orig</file>, in
9561 the current directory.
9565 To create a packed source archive it is typically invoked:
9567 dpkg-source -b <var>package</var>-<var>version</var>
9572 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9573 <file>.diff.gz</file> (if appropriate) in the current
9574 directory. <prgn>dpkg-source</prgn> does not clean the
9575 source tree first - this must be done separately if it is
9580 See also <ref id="pkg-sourcearchives">.</p>
9584 <sect1 id="pkg-dpkg-buildpackage">
9586 <prgn>dpkg-buildpackage</prgn> - overall package-building
9591 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9592 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9593 targets <tt>clean</tt>, <tt>build</tt> and
9594 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9595 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9596 source and binary package upload.
9600 It is usually invoked by hand from the top level of the
9601 built or unbuilt source directory. It may be invoked with
9602 no arguments; useful arguments include:
9603 <taglist compact="compact">
9604 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9607 Do not sign the <tt>.changes</tt> file or the
9608 source package <tt>.dsc</tt> file, respectively.</p>
9610 <tag><tt>-p<var>sign-command</var></tt></tag>
9613 Invoke <var>sign-command</var> instead of finding
9614 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9615 <var>sign-command</var> must behave just like
9616 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9618 <tag><tt>-r<var>root-command</var></tt></tag>
9621 When root privilege is required, invoke the command
9622 <var>root-command</var>. <var>root-command</var>
9623 should invoke its first argument as a command, from
9624 the <prgn>PATH</prgn> if necessary, and pass its
9625 second and subsequent arguments to the command it
9626 calls. If no <var>root-command</var> is supplied
9627 then <var>dpkg-buildpackage</var> will take no
9628 special action to gain root privilege, so that for
9629 most packages it will have to be invoked as root to
9632 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9635 Two types of binary-only build and upload - see
9636 <manref name="dpkg-source" section="1">.
9643 <sect1 id="pkg-dpkg-gencontrol">
9645 <prgn>dpkg-gencontrol</prgn> - generates binary package
9650 This program is usually called from <file>debian/rules</file>
9651 (see <ref id="pkg-sourcetree">) in the top level of the source
9656 This is usually done just before the files and directories in the
9657 temporary directory tree where the package is being built have their
9658 permissions and ownerships set and the package is constructed using
9659 <prgn>dpkg-deb/</prgn>
9661 This is so that the control file which is produced has
9662 the right permissions
9667 <prgn>dpkg-gencontrol</prgn> must be called after all the
9668 files which are to go into the package have been placed in
9669 the temporary build directory, so that its calculation of
9670 the installed size of a package is correct.
9674 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9675 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9676 variable substitutions created by
9677 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9682 For a package which generates only one binary package, and
9683 which builds it in <file>debian/tmp</file> relative to the top
9684 of the source package, it is usually sufficient to call
9685 <prgn>dpkg-gencontrol</prgn>.
9689 Sources which build several binaries will typically need
9692 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9693 </example> The <tt>-P</tt> tells
9694 <prgn>dpkg-gencontrol</prgn> that the package is being
9695 built in a non-default directory, and the <tt>-p</tt>
9696 tells it which package's control file should be generated.
9700 <prgn>dpkg-gencontrol</prgn> also adds information to the
9701 list of files in <file>debian/files</file>, for the benefit of
9702 (for example) a future invocation of
9703 <prgn>dpkg-genchanges</prgn>.</p>
9706 <sect1 id="pkg-dpkg-shlibdeps">
9708 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9713 This program is usually called from <file>debian/rules</file>
9714 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9715 id="pkg-sourcetree">), in the top level of the source tree.
9719 Its arguments are executables and shared libraries
9722 They may be specified either in the locations in the
9723 source tree where they are created or in the locations
9724 in the temporary build tree where they are installed
9725 prior to binary package creation.
9727 </footnote> for which shared library dependencies should
9728 be included in the binary package's control file.
9732 If some of the found shared libraries should only
9733 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9734 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9735 by using the <tt>-d<var>dependency-field</var></tt> option
9736 before those executable(s). (Each <tt>-d</tt> option
9737 takes effect until the next <tt>-d</tt>.)
9741 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9742 output control file to be modified. Instead by default it
9743 adds to the <file>debian/substvars</file> file variable
9744 settings like <tt>shlibs:Depends</tt>. These variable
9745 settings must be referenced in dependency fields in the
9746 appropriate per-binary-package sections of the source
9751 For example, a package that generates an essential part
9752 which requires dependencies, and optional parts that
9753 which only require a recommendation, would separate those
9754 two sets of dependencies into two different fields.<footnote>
9755 At the time of writing, an example for this was the
9756 <package/xmms/ package, with Depends used for the xmms
9757 executable, Recommends for the plug-ins and Suggests for
9758 even more optional features provided by unzip.
9760 It can say in its <file>debian/rules</file>:
9762 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9763 -dRecommends <var>optionalpart anotheroptionalpart</var>
9765 and then in its main control file <file>debian/control</file>:
9768 Depends: ${shlibs:Depends}
9769 Recommends: ${shlibs:Recommends}
9775 Sources which produce several binary packages with
9776 different shared library dependency requirements can use
9777 the <tt>-p<var>varnameprefix</var></tt> option to override
9778 the default <tt>shlibs:</tt> prefix (one invocation of
9779 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9780 They can thus produce several sets of dependency
9781 variables, each of the form
9782 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9783 which can be referred to in the appropriate parts of the
9784 binary package control files.
9789 <sect1 id="pkg-dpkg-distaddfile">
9791 <prgn>dpkg-distaddfile</prgn> - adds a file to
9792 <file>debian/files</file>
9796 Some packages' uploads need to include files other than
9797 the source and binary package files.
9801 <prgn>dpkg-distaddfile</prgn> adds a file to the
9802 <file>debian/files</file> file so that it will be included in
9803 the <file>.changes</file> file when
9804 <prgn>dpkg-genchanges</prgn> is run.
9808 It is usually invoked from the <tt>binary</tt> target of
9809 <file>debian/rules</file>:
9811 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9813 The <var>filename</var> is relative to the directory where
9814 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9815 is usually the directory above the top level of the source
9816 tree. The <file>debian/rules</file> target should put the
9817 file there just before or just after calling
9818 <prgn>dpkg-distaddfile</prgn>.
9822 The <var>section</var> and <var>priority</var> are passed
9823 unchanged into the resulting <file>.changes</file> file.
9828 <sect1 id="pkg-dpkg-genchanges">
9830 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9835 This program is usually called by package-independent
9836 automatic building scripts such as
9837 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9842 It is usually called in the top level of a built source
9843 tree, and when invoked with no arguments will print out a
9844 straightforward <file>.changes</file> file based on the
9845 information in the source package's changelog and control
9846 file and the binary and source packages which should have
9852 <sect1 id="pkg-dpkg-parsechangelog">
9854 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9855 representation of a changelog
9859 This program is used internally by
9860 <prgn>dpkg-source</prgn> et al. It may also occasionally
9861 be useful in <file>debian/rules</file> and elsewhere. It
9862 parses a changelog, <file>debian/changelog</file> by default,
9863 and prints a control-file format representation of the
9864 information in it to standard output.
9868 <sect1 id="pkg-dpkg-architecture">
9870 <prgn>dpkg-architecture</prgn> - information about the build and
9875 This program can be used manually, but is also invoked by
9876 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9877 environment or make variables which specify the build and host
9878 architecture for the package building process.
9883 <sect id="pkg-sourcetree">
9884 <heading>The Debianised source tree</heading>
9887 The source archive scheme described later is intended to
9888 allow a Debianised source tree with some associated control
9889 information to be reproduced and transported easily. The
9890 Debianised source tree is a version of the original program
9891 with certain files added for the benefit of the
9892 Debianisation process, and with any other changes required
9893 made to the rest of the source code and installation
9898 The extra files created for Debian are in the subdirectory
9899 <file>debian</file> of the top level of the Debianised source
9900 tree. They are described below.
9903 <sect1 id="pkg-debianrules">
9904 <heading><file>debian/rules</file> - the main building script</heading>
9907 See <ref id="debianrules">.
9912 <sect1 id="pkg-dpkgchangelog">
9913 <heading><file>debian/changelog</file></heading>
9916 See <ref id="dpkgchangelog">.
9919 <sect2><heading>Defining alternative changelog formats
9923 It is possible to use a different format to the standard
9924 one, by providing a parser for the format you wish to
9929 In order to have <tt>dpkg-parsechangelog</tt> run your
9930 parser, you must include a line within the last 40 lines
9931 of your file matching the Perl regular expression:
9932 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9933 parentheses should be the name of the format. For
9934 example, you might say:
9936 @@@ changelog-format: joebloggs @@@
9938 Changelog format names are non-empty strings of alphanumerics.
9942 If such a line exists then <tt>dpkg-parsechangelog</tt>
9943 will look for the parser as
9944 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9946 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9947 it is an error for it not to find it, or for it not to
9948 be an executable program. The default changelog format
9949 is <tt>dpkg</tt>, and a parser for it is provided with
9950 the <tt>dpkg</tt> package.
9954 The parser will be invoked with the changelog open on
9955 standard input at the start of the file. It should read
9956 the file (it may seek if it wishes) to determine the
9957 information required and return the parsed information
9958 to standard output in the form of a series of control
9959 fields in the standard format. By default it should
9960 return information about only the most recent version in
9961 the changelog; it should accept a
9962 <tt>-v<var>version</var></tt> option to return changes
9963 information from all versions present <em>strictly
9964 after</em> <var>version</var>, and it should then be an
9965 error for <var>version</var> not to be present in the
9971 <list compact="compact">
9972 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9973 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9974 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9975 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9976 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9977 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9978 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9983 If several versions are being returned (due to the use
9984 of <tt>-v</tt>), the urgency value should be of the
9985 highest urgency code listed at the start of any of the
9986 versions requested followed by the concatenated
9987 (space-separated) comments from all the versions
9988 requested; the maintainer, version, distribution and
9989 date should always be from the most recent version.
9993 For the format of the <tt>Changes</tt> field see
9994 <ref id="f-Changes">.
9998 If the changelog format which is being parsed always or
9999 almost always leaves a blank line between individual
10000 change notes these blank lines should be stripped out,
10001 so as to make the resulting output compact.
10005 If the changelog format does not contain date or package
10006 name information this information should be omitted from
10007 the output. The parser should not attempt to synthesize
10008 it or find it from other sources.
10012 If the changelog does not have the expected format the
10013 parser should exit with a nonzero exit status, rather
10014 than trying to muddle through and possibly generating
10019 A changelog parser may not interact with the user at
10025 <sect1 id="pkg-srcsubstvars">
10026 <heading><file>debian/substvars</file> and variable substitutions</heading>
10029 See <ref id="substvars">.
10035 <heading><file>debian/files</file></heading>
10038 See <ref id="debianfiles">.
10042 <sect1><heading><file>debian/tmp</file>
10046 This is the canonical temporary location for the
10047 construction of binary packages by the <tt>binary</tt>
10048 target. The directory <file>tmp</file> serves as the root of
10049 the file system tree as it is being constructed (for
10050 example, by using the package's upstream makefiles install
10051 targets and redirecting the output there), and it also
10052 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10053 id="pkg-bincreating">.
10057 If several binary packages are generated from the same
10058 source tree it is usual to use several
10059 <file>debian/tmp<var>something</var></file> directories, for
10060 example <file>tmp-a</file> or <file>tmp-doc</file>.
10064 Whatever <file>tmp</file> directories are created and used by
10065 <tt>binary</tt> must of course be removed by the
10066 <tt>clean</tt> target.</p></sect1>
10070 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10074 As it exists on the FTP site, a Debian source package
10075 consists of three related files. You must have the right
10076 versions of all three to be able to use them.
10081 <tag>Debian source control file - <tt>.dsc</tt></tag>
10083 This file is a control file used by <prgn>dpkg-source</prgn>
10084 to extract a source package.
10085 See <ref id="debiansourcecontrolfiles">.
10089 Original source archive -
10091 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10097 This is a compressed (with <tt>gzip -9</tt>)
10098 <prgn>tar</prgn> file containing the source code from
10099 the upstream authors of the program.
10104 Debianisation diff -
10106 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10112 This is a unified context diff (<tt>diff -u</tt>)
10113 giving the changes which are required to turn the
10114 original source into the Debian source. These changes
10115 may only include editing and creating plain files.
10116 The permissions of files, the targets of symbolic
10117 links and the characteristics of special files or
10118 pipes may not be changed and no files may be removed
10123 All the directories in the diff must exist, except the
10124 <file>debian</file> subdirectory of the top of the source
10125 tree, which will be created by
10126 <prgn>dpkg-source</prgn> if necessary when unpacking.
10130 The <prgn>dpkg-source</prgn> program will
10131 automatically make the <file>debian/rules</file> file
10132 executable (see below).</p></item>
10137 If there is no original source code - for example, if the
10138 package is specially prepared for Debian or the Debian
10139 maintainer is the same as the upstream maintainer - the
10140 format is slightly different: then there is no diff, and the
10142 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10143 and preferably contains a directory named
10144 <file><var>package</var>-<var>version</var></file>.
10149 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10152 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10153 Debian source package. However, if it is not available it
10154 is possible to unpack a Debian source archive as follows:
10155 <enumlist compact="compact">
10158 Untar the tarfile, which will create a <file>.orig</file>
10162 <p>Rename the <file>.orig</file> directory to
10163 <file><var>package</var>-<var>version</var></file>.</p>
10167 Create the subdirectory <file>debian</file> at the top of
10168 the source tree.</p>
10170 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10172 <item><p>Untar the tarfile again if you want a copy of the original
10173 source code alongside the Debianised version.</p>
10178 It is not possible to generate a valid Debian source archive
10179 without using <prgn>dpkg-source</prgn>. In particular,
10180 attempting to use <prgn>diff</prgn> directly to generate the
10181 <file>.diff.gz</file> file will not work.
10185 <heading>Restrictions on objects in source packages</heading>
10188 The source package may not contain any hard links
10190 This is not currently detected when building source
10191 packages, but only when extracting
10195 Hard links may be permitted at some point in the
10196 future, but would require a fair amount of
10198 </footnote>, device special files, sockets or setuid or
10201 Setgid directories are allowed.
10206 The source packaging tools manage the changes between the
10207 original and Debianised source using <prgn>diff</prgn> and
10208 <prgn>patch</prgn>. Turning the original source tree as
10209 included in the <file>.orig.tar.gz</file> into the debianised
10210 source must not involve any changes which cannot be
10211 handled by these tools. Problematic changes which cause
10212 <prgn>dpkg-source</prgn> to halt with an error when
10213 building the source package are:
10214 <list compact="compact">
10215 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10217 <item><p>Changing the targets of symbolic links.</p>
10219 <item><p>Creating directories, other than <file>debian</file>.</p>
10221 <item><p>Changes to the contents of binary files.</p></item>
10222 </list> Changes which cause <prgn>dpkg-source</prgn> to
10223 print a warning but continue anyway are:
10224 <list compact="compact">
10227 Removing files, directories or symlinks.
10229 Renaming a file is not treated specially - it is
10230 seen as the removal of the old file (which
10231 generates a warning, but is otherwise ignored),
10232 and the creation of the new one.
10238 Changed text files which are missing the usual final
10239 newline (either in the original or the modified
10244 Changes which are not represented, but which are not detected by
10245 <prgn>dpkg-source</prgn>, are:
10246 <list compact="compact">
10247 <item><p>Changing the permissions of files (other than
10248 <file>debian/rules</file>) and directories.</p></item>
10253 The <file>debian</file> directory and <file>debian/rules</file>
10254 are handled specially by <prgn>dpkg-source</prgn> - before
10255 applying the changes it will create the <file>debian</file>
10256 directory, and afterwards it will make
10257 <file>debian/rules</file> world-executable.
10263 <appendix id="pkg-controlfields">
10264 <heading>Control files and their fields (from old Packaging Manual)</heading>
10267 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10268 data in a common format, known as control files. Binary and
10269 source packages have control data as do the <file>.changes</file>
10270 files which control the installation of uploaded files, and
10271 <prgn>dpkg</prgn>'s internal databases are in a similar
10276 <heading>Syntax of control files</heading>
10279 See <ref id="controlsyntax">.
10283 It is important to note that there are several fields which
10284 are optional as far as <prgn>dpkg</prgn> and the related
10285 tools are concerned, but which must appear in every Debian
10286 package, or whose omission may cause problems.
10291 <heading>List of fields</heading>
10294 See <ref id="controlfieldslist">.
10298 This section now contains only the fields that didn't belong
10299 to the Policy manual.
10302 <sect1 id="pkg-f-Filename">
10303 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10306 These fields in <tt>Packages</tt> files give the
10307 filename(s) of (the parts of) a package in the
10308 distribution directories, relative to the root of the
10309 Debian hierarchy. If the package has been split into
10310 several parts the parts are all listed in order, separated
10315 <sect1 id="pkg-f-Size">
10316 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10319 These fields in <file>Packages</file> files give the size (in
10320 bytes, expressed in decimal) and MD5 checksum of the
10321 file(s) which make(s) up a binary package in the
10322 distribution. If the package is split into several parts
10323 the values for the parts are listed in order, separated by
10328 <sect1 id="pkg-f-Status">
10329 <heading><tt>Status</tt></heading>
10332 This field in <prgn>dpkg</prgn>'s status file records
10333 whether the user wants a package installed, removed or
10334 left alone, whether it is broken (requiring
10335 re-installation) or not and what its current state on the
10336 system is. Each of these pieces of information is a
10341 <sect1 id="pkg-f-Config-Version">
10342 <heading><tt>Config-Version</tt></heading>
10345 If a package is not installed or not configured, this
10346 field in <prgn>dpkg</prgn>'s status file records the last
10347 version of the package which was successfully
10352 <sect1 id="pkg-f-Conffiles">
10353 <heading><tt>Conffiles</tt></heading>
10356 This field in <prgn>dpkg</prgn>'s status file contains
10357 information about the automatically-managed configuration
10358 files held by a package. This field should <em>not</em>
10359 appear anywhere in a package!
10364 <heading>Obsolete fields</heading>
10367 These are still recognized by <prgn>dpkg</prgn> but should
10368 not appear anywhere any more.
10370 <taglist compact="compact">
10372 <tag><tt>Revision</tt></tag>
10373 <tag><tt>Package-Revision</tt></tag>
10374 <tag><tt>Package_Revision</tt></tag>
10376 The Debian revision part of the package version was
10377 at one point in a separate control file field. This
10378 field went through several names.
10381 <tag><tt>Recommended</tt></tag>
10382 <item>Old name for <tt>Recommends</tt>.</item>
10384 <tag><tt>Optional</tt></tag>
10385 <item>Old name for <tt>Suggests</tt>.</item>
10387 <tag><tt>Class</tt></tag>
10388 <item>Old name for <tt>Priority</tt>.</item>
10397 <appendix id="pkg-conffiles">
10398 <heading>Configuration file handling (from old Packaging Manual)</heading>
10401 <prgn>dpkg</prgn> can do a certain amount of automatic
10402 handling of package configuration files.
10406 Whether this mechanism is appropriate depends on a number of
10407 factors, but basically there are two approaches to any
10408 particular configuration file.
10412 The easy method is to ship a best-effort configuration in the
10413 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10414 handle updates. If the user is unlikely to want to edit the
10415 file, but you need them to be able to without losing their
10416 changes, and a new package with a changed version of the file
10417 is only released infrequently, this is a good approach.
10421 The hard method is to build the configuration file from
10422 scratch in the <prgn>postinst</prgn> script, and to take the
10423 responsibility for fixing any mistakes made in earlier
10424 versions of the package automatically. This will be
10425 appropriate if the file is likely to need to be different on
10429 <sect><heading>Automatic handling of configuration files by
10434 A package may contain a control area file called
10435 <tt>conffiles</tt>. This file should be a list of filenames
10436 of configuration files needing automatic handling, separated
10437 by newlines. The filenames should be absolute pathnames,
10438 and the files referred to should actually exist in the
10443 When a package is upgraded <prgn>dpkg</prgn> will process
10444 the configuration files during the configuration stage,
10445 shortly before it runs the package's <prgn>postinst</prgn>
10450 For each file it checks to see whether the version of the
10451 file included in the package is the same as the one that was
10452 included in the last version of the package (the one that is
10453 being upgraded from); it also compares the version currently
10454 installed on the system with the one shipped with the last
10459 If neither the user nor the package maintainer has changed
10460 the file, it is left alone. If one or the other has changed
10461 their version, then the changed version is preferred - i.e.,
10462 if the user edits their file, but the package maintainer
10463 doesn't ship a different version, the user's changes will
10464 stay, silently, but if the maintainer ships a new version
10465 and the user hasn't edited it the new version will be
10466 installed (with an informative message). If both have
10467 changed their version the user is prompted about the problem
10468 and must resolve the differences themselves.
10472 The comparisons are done by calculating the MD5 message
10473 digests of the files, and storing the MD5 of the file as it
10474 was included in the most recent version of the package.
10478 When a package is installed for the first time
10479 <prgn>dpkg</prgn> will install the file that comes with it,
10480 unless that would mean overwriting a file already on the
10485 However, note that <prgn>dpkg</prgn> will <em>not</em>
10486 replace a conffile that was removed by the user (or by a
10487 script). This is necessary because with some programs a
10488 missing file produces an effect hard or impossible to
10489 achieve in another way, so that a missing file needs to be
10490 kept that way if the user did it.
10494 Note that a package should <em>not</em> modify a
10495 <prgn>dpkg</prgn>-handled conffile in its maintainer
10496 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10497 the user confusing and possibly dangerous options for
10498 conffile update when the package is upgraded.</p>
10501 <sect><heading>Fully-featured maintainer script configuration
10506 For files which contain site-specific information such as
10507 the hostname and networking details and so forth, it is
10508 better to create the file in the package's
10509 <prgn>postinst</prgn> script.
10513 This will typically involve examining the state of the rest
10514 of the system to determine values and other information, and
10515 may involve prompting the user for some information which
10516 can't be obtained some other way.
10520 When using this method there are a couple of important
10521 issues which should be considered:
10525 If you discover a bug in the program which generates the
10526 configuration file, or if the format of the file changes
10527 from one version to the next, you will have to arrange for
10528 the postinst script to do something sensible - usually this
10529 will mean editing the installed configuration file to remove
10530 the problem or change the syntax. You will have to do this
10531 very carefully, since the user may have changed the file,
10532 perhaps to fix the very problem that your script is trying
10533 to deal with - you will have to detect these situations and
10534 deal with them correctly.
10538 If you do go down this route it's probably a good idea to
10539 make the program that generates the configuration file(s) a
10540 separate program in <file>/usr/sbin</file>, by convention called
10541 <file><var>package</var>config</file> and then run that if
10542 appropriate from the post-installation script. The
10543 <tt><var>package</var>config</tt> program should not
10544 unquestioningly overwrite an existing configuration - if its
10545 mode of operation is geared towards setting up a package for
10546 the first time (rather than any arbitrary reconfiguration
10547 later) you should have it check whether the configuration
10548 already exists, and require a <tt>--force</tt> flag to
10549 overwrite it.</p></sect>
10552 <appendix id="pkg-alternatives"><heading>Alternative versions of
10553 an interface - <prgn>update-alternatives</prgn> (from old
10558 When several packages all provide different versions of the
10559 same program or file it is useful to have the system select a
10560 default, but to allow the system administrator to change it
10561 and have their decisions respected.
10565 For example, there are several versions of the <prgn>vi</prgn>
10566 editor, and there is no reason to prevent all of them from
10567 being installed at once, each under their own name
10568 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10569 Nevertheless it is desirable to have the name <tt>vi</tt>
10570 refer to something, at least by default.
10574 If all the packages involved cooperate, this can be done with
10575 <prgn>update-alternatives</prgn>.
10579 Each package provides its own version under its own name, and
10580 calls <prgn>update-alternatives</prgn> in its postinst to
10581 register its version (and again in its prerm to deregister
10586 See the man page <manref name="update-alternatives"
10587 section="8"> for details.
10591 If <prgn>update-alternatives</prgn> does not seem appropriate
10592 you may wish to consider using diversions instead.</p>
10595 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10596 package's version of a file (from old Packaging Manual)
10600 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10601 when it reinstalls the package it belongs to, and to have it
10602 put the file from the package somewhere else instead.
10606 This can be used locally to override a package's version of a
10607 file, or by one package to override another's version (or
10608 provide a wrapper for it).
10612 Before deciding to use a diversion, read <ref
10613 id="pkg-alternatives"> to see if you really want a diversion
10614 rather than several alternative versions of a program.
10618 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10619 and updated by a special program <prgn>dpkg-divert</prgn>.
10620 Please see <manref name="dpkg-divert" section="8"> for full
10621 details of its operation.
10625 When a package wishes to divert a file from another, it should
10626 call <prgn>dpkg-divert</prgn> in its preinst to add the
10627 diversion and rename the existing file. For example,
10628 supposing that a <prgn>smailwrapper</prgn> package wishes to
10629 install a wrapper around <file>/usr/sbin/smail</file>:
10631 dpkg-divert --package smailwrapper --add --rename \
10632 --divert /usr/sbin/smail.real /usr/sbin/smail
10633 </example> The <tt>--package smailwrapper</tt> ensures that
10634 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10635 can bypass the diversion and get installed as the true version.
10636 It's safe to add the diversion unconditionally on upgrades since
10637 it will be left unchanged if it already exists, but
10638 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10639 message, make the command conditional on the version from which
10640 the package is being upgraded:
10642 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10643 dpkg-divert --package smailwrapper --add --rename \
10644 --divert /usr/sbin/smail.real /usr/sbin/smail
10646 </example> where <tt>1.0-2</tt> is the version at which the
10647 diversion was first added to the package. Running the command
10648 during abort-upgrade is pointless but harmless.
10652 The postrm has to do the reverse:
10654 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10655 dpkg-divert --package smailwrapper --remove --rename \
10656 --divert /usr/sbin/smail.real /usr/sbin/smail
10658 </example> If the diversion was added at a particular version, the
10659 postrm should also handle the failure case of upgrading from an
10660 older version (unless the older version is so old that direct
10661 upgrades are no longer supported):
10663 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10664 dpkg-divert --package smailwrapper --remove --rename \
10665 --divert /usr/sbin/smail.real /usr/sbin/smail
10667 </example> where <tt>1.02-2</tt> is the version at which the
10668 diversion was first added to the package. The postrm should not
10669 remove the diversion on upgrades both because there's no reason to
10670 remove the diversion only to immediately re-add it and since the
10671 postrm of the old package is run after unpacking so the removal of
10672 the diversion will fail.
10676 Do not attempt to divert a file which is vitally important for
10677 the system's operation - when using <prgn>dpkg-divert</prgn>
10678 there is a time, after it has been diverted but before
10679 <prgn>dpkg</prgn> has installed the new version, when the file
10680 does not exist.</p>
10685 <!-- Local variables: -->
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