1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy"
161 id="http://packages.debian.org/debian-policy"></package>
162 (<httpsite>packages.debian.org</httpsite>
163 <httppath>/debian-policy</httppath>).
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name="/doc/debian-policy/"
170 id="http://www.debian.org/doc/debian-policy/"></tt>.
172 <httpsite>www.debian.org</httpsite>
173 <httppath>/doc/debian-policy/</httppath>)
174 Also available from the same directory are several other
175 formats: <file>policy.html.tar.gz</file>
176 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
177 <file>policy.pdf.gz</file>
178 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
179 and <file>policy.ps.gz</file>
180 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
184 The <package>debian-policy</package> package also includes the file
185 <file>upgrading-checklist.txt.gz</file> which indicates policy
186 changes between versions of this document.
191 <heading>Authors and Maintainers</heading>
194 Originally called "Debian GNU/Linux Policy Manual", this
195 manual was initially written in 1996 by Ian Jackson.
196 It was revised on November 27th, 1996 by David A. Morris.
197 Christian Schwarz added new sections on March 15th, 1997,
198 and reworked/restructured it in April-July 1997.
199 Christoph Lameter contributed the "Web Standard".
200 Julian Gilbey largely restructured it in 2001.
204 Since September 1998, the responsibility for the contents of
205 this document lies on the <url name="debian-policy mailing list"
206 id="mailto:debian-policy@lists.debian.org">. Proposals
207 are discussed there and inserted into policy after a certain
208 consensus is established.
209 <!-- insert shameless policy-process plug here eventually -->
210 The actual editing is done by a group of maintainers that have
211 no editorial powers. These are the current maintainers:
214 <item>Julian Gilbey</item>
215 <item>Branden Robinson</item>
216 <item>Josip Rodin</item>
217 <item>Manoj Srivastava</item>
222 While the authors of this document have tried hard to avoid
223 typos and other errors, these do still occur. If you discover
224 an error in this manual or if you want to give any
225 comments, suggestions, or criticisms please send an email to
226 the Debian Policy List,
227 <email>debian-policy@lists.debian.org</email>, or submit a
228 bug report against the <tt>debian-policy</tt> package.
232 Please do not try to reach the individual authors or maintainers
233 of the Policy Manual regarding changes to the Policy.
238 <heading>Related documents</heading>
241 There are several other documents other than this Policy Manual
242 that are necessary to fully understand some Debian policies and
247 The external "sub-policy" documents are referred to in:
248 <list compact="compact">
249 <item><ref id="fhs"></item>
250 <item><ref id="virtual_pkg"></item>
251 <item><ref id="menus"></item>
252 <item><ref id="mime"></item>
253 <item><ref id="perl"></item>
254 <item><ref id="maintscriptprompt"></item>
255 <item><ref id="emacs"></item>
260 In addition to those, which carry the weight of policy, there
261 is the Debian Developer's Reference. This document describes
262 procedures and resources for Debian developers, but it is
263 <em>not</em> normative; rather, it includes things that don't
264 belong in the Policy, such as best practices for developers.
268 The Developer's Reference is available in the
269 <package>developers-reference</package> package.
270 It's also available from the Debian web mirrors at
271 <tt><url name="/doc/developers-reference/"
272 id="http://www.debian.org/doc/developers-reference/"></tt>.
276 <sect id="definitions">
277 <heading>Definitions</heading>
280 The following terms are used in this Policy Manual:
284 The character encoding specified by ANSI X3.4-1986 and its
285 predecessor standards, referred to in MIME as US-ASCII, and
286 corresponding to an encoding in eight bits per character of
287 the first 128 <url id="http://www.unicode.org/"
288 name="Unicode"> characters, with the eighth bit always zero.
292 The transformation format (sometimes called encoding) of
293 <url id="http://www.unicode.org/" name="Unicode"> defined by
294 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
295 name="RFC 3629">. UTF-8 has the useful property of having
296 ASCII as a subset, so any text encoded in ASCII is trivially
306 <heading>The Debian Archive</heading>
309 The Debian GNU/Linux system is maintained and distributed as a
310 collection of <em>packages</em>. Since there are so many of
311 them (currently well over 15000), they are split into
312 <em>sections</em> and given <em>priorities</em> to simplify
313 the handling of them.
317 The effort of the Debian project is to build a free operating
318 system, but not every package we want to make accessible is
319 <em>free</em> in our sense (see the Debian Free Software
320 Guidelines, below), or may be imported/exported without
321 restrictions. Thus, the archive is split into areas<footnote>
322 The Debian archive software uses the term "component" internally
323 and in the Release file format to refer to the division of an
324 archive. The Debian Social Contract simply refers to "areas."
325 This document uses terminology similar to the Social Contract.
326 </footnote> based on their licenses and other restrictions.
330 The aims of this are:
332 <list compact="compact">
333 <item>to allow us to make as much software available as we can</item>
334 <item>to allow us to encourage everyone to write free software,
336 <item>to allow us to make it easy for people to produce
337 CD-ROMs of our system without violating any licenses,
338 import/export restrictions, or any other laws.</item>
343 The <em>main</em> archive area forms the <em>Debian GNU/Linux
348 Packages in the other archive areas (<tt>contrib</tt>,
349 <tt>non-free</tt>) are not considered to be part of the Debian
350 distribution, although we support their use and provide
351 infrastructure for them (such as our bug-tracking system and
352 mailing lists). This Debian Policy Manual applies to these
357 <heading>The Debian Free Software Guidelines</heading>
359 The Debian Free Software Guidelines (DFSG) form our
360 definition of "free software". These are:
362 <tag>Free Redistribution
365 The license of a Debian component may not restrict any
366 party from selling or giving away the software as a
367 component of an aggregate software distribution
368 containing programs from several different
369 sources. The license may not require a royalty or
370 other fee for such sale.
375 The program must include source code, and must allow
376 distribution in source code as well as compiled form.
381 The license must allow modifications and derived
382 works, and must allow them to be distributed under the
383 same terms as the license of the original software.
385 <tag>Integrity of The Author's Source Code
388 The license may restrict source-code from being
389 distributed in modified form <em>only</em> if the
390 license allows the distribution of "patch files"
391 with the source code for the purpose of modifying the
392 program at build time. The license must explicitly
393 permit distribution of software built from modified
394 source code. The license may require derived works to
395 carry a different name or version number from the
396 original software. (This is a compromise. The Debian
397 Project encourages all authors to not restrict any
398 files, source or binary, from being modified.)
400 <tag>No Discrimination Against Persons or Groups
403 The license must not discriminate against any person
406 <tag>No Discrimination Against Fields of Endeavor
409 The license must not restrict anyone from making use
410 of the program in a specific field of endeavor. For
411 example, it may not restrict the program from being
412 used in a business, or from being used for genetic
415 <tag>Distribution of License
418 The rights attached to the program must apply to all
419 to whom the program is redistributed without the need
420 for execution of an additional license by those
423 <tag>License Must Not Be Specific to Debian
426 The rights attached to the program must not depend on
427 the program's being part of a Debian system. If the
428 program is extracted from Debian and used or
429 distributed without Debian but otherwise within the
430 terms of the program's license, all parties to whom
431 the program is redistributed must have the same
432 rights as those that are granted in conjunction with
435 <tag>License Must Not Contaminate Other Software
438 The license must not place restrictions on other
439 software that is distributed along with the licensed
440 software. For example, the license must not insist
441 that all other programs distributed on the same medium
442 must be free software.
444 <tag>Example Licenses
447 The "GPL," "BSD," and "Artistic" licenses are examples of
448 licenses that we consider <em>free</em>.
455 <heading>Archive areas</heading>
458 <heading>The main archive area</heading>
461 Every package in <em>main</em> must comply with the DFSG
462 (Debian Free Software Guidelines).
466 In addition, the packages in <em>main</em>
467 <list compact="compact">
469 must not require a package outside of <em>main</em>
470 for compilation or execution (thus, the package must
471 not declare a "Depends", "Recommends", or
472 "Build-Depends" relationship on a non-<em>main</em>
476 must not be so buggy that we refuse to support them,
480 must meet all policy requirements presented in this
489 <heading>The contrib archive area</heading>
492 Every package in <em>contrib</em> must comply with the DFSG.
496 In addition, the packages in <em>contrib</em>
497 <list compact="compact">
499 must not be so buggy that we refuse to support them,
503 must meet all policy requirements presented in this
511 Examples of packages which would be included in
512 <em>contrib</em> are:
513 <list compact="compact">
515 free packages which require <em>contrib</em>,
516 <em>non-free</em> packages or packages which are not
517 in our archive at all for compilation or execution,
521 wrapper packages or other sorts of free accessories for
528 <sect1 id="non-free">
529 <heading>The non-free archive area</heading>
532 Packages must be placed in <em>non-free</em> if they are
533 not compliant with the DFSG or are encumbered by patents
534 or other legal issues that make their distribution
539 In addition, the packages in <em>non-free</em>
540 <list compact="compact">
542 must not be so buggy that we refuse to support them,
546 must meet all policy requirements presented in this
547 manual that it is possible for them to meet.
549 It is possible that there are policy
550 requirements which the package is unable to
551 meet, for example, if the source is
552 unavailable. These situations will need to be
553 handled on a case-by-case basis.
562 <sect id="pkgcopyright">
563 <heading>Copyright considerations</heading>
566 Every package must be accompanied by a verbatim copy of
567 its copyright and distribution license in the file
568 <file>/usr/share/doc/<var>package</var>/copyright</file>
569 (see <ref id="copyrightfile"> for further details).
573 We reserve the right to restrict files from being included
574 anywhere in our archives if
575 <list compact="compact">
577 their use or distribution would break a law,
580 there is an ethical conflict in their distribution or
584 we would have to sign a license for them, or
587 their distribution would conflict with other project
594 Programs whose authors encourage the user to make
595 donations are fine for the main distribution, provided
596 that the authors do not claim that not donating is
597 immoral, unethical, illegal or something similar; in such
598 a case they must go in <em>non-free</em>.
602 Packages whose copyright permission notices (or patent
603 problems) do not even allow redistribution of binaries
604 only, and where no special permission has been obtained,
605 must not be placed on the Debian FTP site and its mirrors
610 Note that under international copyright law (this applies
611 in the United States, too), <em>no</em> distribution or
612 modification of a work is allowed without an explicit
613 notice saying so. Therefore a program without a copyright
614 notice <em>is</em> copyrighted and you may not do anything
615 to it without risking being sued! Likewise if a program
616 has a copyright notice but no statement saying what is
617 permitted then nothing is permitted.
621 Many authors are unaware of the problems that restrictive
622 copyrights (or lack of copyright notices) can cause for
623 the users of their supposedly-free software. It is often
624 worthwhile contacting such authors diplomatically to ask
625 them to modify their license terms. However, this can be a
626 politically difficult thing to do and you should ask for
627 advice on the <tt>debian-legal</tt> mailing list first, as
632 When in doubt about a copyright, send mail to
633 <email>debian-legal@lists.debian.org</email>. Be prepared
634 to provide us with the copyright statement. Software
635 covered by the GPL, public domain software and BSD-like
636 copyrights are safe; be wary of the phrases "commercial
637 use prohibited" and "distribution restricted".
641 <sect id="subsections">
642 <heading>Sections</heading>
645 The packages in the archive areas <em>main</em>,
646 <em>contrib</em> and <em>non-free</em> are grouped further into
647 <em>sections</em> to simplify handling.
651 The archive area and section for each package should be
652 specified in the package's <tt>Section</tt> control record (see
653 <ref id="f-Section">). However, the maintainer of the Debian
654 archive may override this selection to ensure the consistency of
655 the Debian distribution. The <tt>Section</tt> field should be
657 <list compact="compact">
659 <em>section</em> if the package is in the
660 <em>main</em> archive area,
663 <em>area/section</em> if the package is in
664 the <em>contrib</em> or <em>non-free</em>
671 The Debian archive maintainers provide the authoritative
672 list of sections. At present, they are:
673 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
674 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
675 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
676 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
677 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
678 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
679 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
680 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
681 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
682 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
683 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
684 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
685 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
690 <sect id="priorities">
691 <heading>Priorities</heading>
694 Each package should have a <em>priority</em> value, which is
695 included in the package's <em>control record</em>
696 (see <ref id="f-Priority">).
697 This information is used by the Debian package management tools to
698 separate high-priority packages from less-important packages.
702 The following <em>priority levels</em> are recognized by the
703 Debian package management tools.
705 <tag><tt>required</tt></tag>
707 Packages which are necessary for the proper
708 functioning of the system (usually, this means that
709 dpkg functionality depends on these packages).
710 Removing a <tt>required</tt> package may cause your
711 system to become totally broken and you may not even
712 be able to use <prgn>dpkg</prgn> to put things back,
713 so only do so if you know what you are doing. Systems
714 with only the <tt>required</tt> packages are probably
715 unusable, but they do have enough functionality to
716 allow the sysadmin to boot and install more software.
718 <tag><tt>important</tt></tag>
720 Important programs, including those which one would
721 expect to find on any Unix-like system. If the
722 expectation is that an experienced Unix person who
723 found it missing would say "What on earth is going on,
724 where is <prgn>foo</prgn>?", it must be an
725 <tt>important</tt> package.<footnote>
726 This is an important criterion because we are
727 trying to produce, amongst other things, a free
730 Other packages without which the system will not run
731 well or be usable must also have priority
732 <tt>important</tt>. This does
733 <em>not</em> include Emacs, the X Window System, TeX
734 or any other large applications. The
735 <tt>important</tt> packages are just a bare minimum of
736 commonly-expected and necessary tools.
738 <tag><tt>standard</tt></tag>
740 These packages provide a reasonably small but not too
741 limited character-mode system. This is what will be
742 installed by default if the user doesn't select anything
743 else. It doesn't include many large applications.
745 <tag><tt>optional</tt></tag>
747 (In a sense everything that isn't required is
748 optional, but that's not what is meant here.) This is
749 all the software that you might reasonably want to
750 install if you didn't know what it was and don't have
751 specialized requirements. This is a much larger system
752 and includes the X Window System, a full TeX
753 distribution, and many applications. Note that
754 optional packages should not conflict with each other.
756 <tag><tt>extra</tt></tag>
758 This contains all packages that conflict with others
759 with required, important, standard or optional
760 priorities, or are only likely to be useful if you
761 already know what they are or have specialized
762 requirements (such as packages containing only detached
769 Packages must not depend on packages with lower priority
770 values (excluding build-time dependencies). In order to
771 ensure this, the priorities of one or more packages may need
780 <heading>Binary packages</heading>
783 The Debian GNU/Linux distribution is based on the Debian
784 package management system, called <prgn>dpkg</prgn>. Thus,
785 all packages in the Debian distribution must be provided
786 in the <tt>.deb</tt> file format.
790 <heading>The package name</heading>
793 Every package must have a name that's unique within the Debian
798 The package name is included in the control field
799 <tt>Package</tt>, the format of which is described
800 in <ref id="f-Package">.
801 The package name is also included as a part of the file name
802 of the <tt>.deb</tt> file.
807 <heading>The version of a package</heading>
810 Every package has a version number recorded in its
811 <tt>Version</tt> control file field, described in
812 <ref id="f-Version">.
816 The package management system imposes an ordering on version
817 numbers, so that it can tell whether packages are being up- or
818 downgraded and so that package system front end applications
819 can tell whether a package it finds available is newer than
820 the one installed on the system. The version number format
821 has the most significant parts (as far as comparison is
822 concerned) at the beginning.
826 If an upstream package has problematic version numbers they
827 should be converted to a sane form for use in the
828 <tt>Version</tt> field.
832 <heading>Version numbers based on dates</heading>
835 In general, Debian packages should use the same version
836 numbers as the upstream sources.
840 However, in some cases where the upstream version number is
841 based on a date (e.g., a development "snapshot" release) the
842 package management system cannot handle these version
843 numbers without epochs. For example, dpkg will consider
844 "96May01" to be greater than "96Dec24".
848 To prevent having to use epochs for every new upstream
849 version, the date based portion of the version number
850 should be changed to the following format in such cases:
851 "19960501", "19961224". It is up to the maintainer whether
852 they want to bother the upstream maintainer to change
853 the version numbers upstream, too.
857 Note that other version formats based on dates which are
858 parsed correctly by the package management system should
859 <em>not</em> be changed.
863 Native Debian packages (i.e., packages which have been
864 written especially for Debian) whose version numbers include
865 dates should always use the "YYYYMMDD" format.
872 <heading>The maintainer of a package</heading>
875 Every package must have a Debian maintainer (the
876 maintainer may be one person or a group of people
877 reachable from a common email address, such as a mailing
878 list). The maintainer is responsible for ensuring that
879 the package is placed in the appropriate distributions.
883 The maintainer must be specified in the
884 <tt>Maintainer</tt> control field with their correct name
885 and a working email address. If one person maintains
886 several packages, they should try to avoid having
887 different forms of their name and email address in
888 the <tt>Maintainer</tt> fields of those packages.
892 The format of the <tt>Maintainer</tt> control field is
893 described in <ref id="f-Maintainer">.
897 If the maintainer of a package quits from the Debian
898 project, "Debian QA Group"
899 <email>packages@qa.debian.org</email> takes over the
900 maintainer-ship of the package until someone else
901 volunteers for that task. These packages are called
902 <em>orphaned packages</em>.<footnote>
903 The detailed procedure for doing this gracefully can
904 be found in the Debian Developer's Reference,
905 see <ref id="related">.
910 <sect id="descriptions">
911 <heading>The description of a package</heading>
914 Every Debian package must have an extended description
915 stored in the appropriate field of the control record.
916 The technical information about the format of the
917 <tt>Description</tt> field is in <ref id="f-Description">.
921 The description should describe the package (the program) to a
922 user (system administrator) who has never met it before so that
923 they have enough information to decide whether they want to
924 install it. This description should not just be copied verbatim
925 from the program's documentation.
929 Put important information first, both in the synopsis and
930 extended description. Sometimes only the first part of the
931 synopsis or of the description will be displayed. You can
932 assume that there will usually be a way to see the whole
933 extended description.
937 The description should also give information about the
938 significant dependencies and conflicts between this package
939 and others, so that the user knows why these dependencies and
940 conflicts have been declared.
944 Instructions for configuring or using the package should
945 not be included (that is what installation scripts,
946 manual pages, info files, etc., are for). Copyright
947 statements and other administrivia should not be included
948 either (that is what the copyright file is for).
951 <sect1 id="synopsis"><heading>The single line synopsis</heading>
954 The single line synopsis should be kept brief - certainly
959 Do not include the package name in the synopsis line. The
960 display software knows how to display this already, and you
961 do not need to state it. Remember that in many situations
962 the user may only see the synopsis line - make it as
963 informative as you can.
968 <sect1 id="extendeddesc"><heading>The extended description</heading>
971 Do not try to continue the single line synopsis into the
972 extended description. This will not work correctly when
973 the full description is displayed, and makes no sense
974 where only the summary (the single line synopsis) is
979 The extended description should describe what the package
980 does and how it relates to the rest of the system (in terms
981 of, for example, which subsystem it is which part of).
985 The description field needs to make sense to anyone, even
986 people who have no idea about any of the things the
987 package deals with.<footnote>
988 The blurb that comes with a program in its
989 announcements and/or <prgn>README</prgn> files is
990 rarely suitable for use in a description. It is
991 usually aimed at people who are already in the
992 community where the package is used.
1001 <heading>Dependencies</heading>
1004 Every package must specify the dependency information
1005 about other packages that are required for the first to
1010 For example, a dependency entry must be provided for any
1011 shared libraries required by a dynamically-linked executable
1012 binary in a package.
1016 Packages are not required to declare any dependencies they
1017 have on other packages which are marked <tt>Essential</tt>
1018 (see below), and should not do so unless they depend on a
1019 particular version of that package.<footnote>
1021 Essential is needed in part to avoid unresolvable dependency
1022 loops on upgrade. If packages add unnecessary dependencies
1023 on packages in this set, the chances that there
1024 <strong>will</strong> be an unresolvable dependency loop
1025 caused by forcing these Essential packages to be configured
1026 first before they need to be is greatly increased. It also
1027 increases the chances that frontends will be unable to
1028 <strong>calculate</strong> an upgrade path, even if one
1032 Also, functionality is rarely ever removed from the
1033 Essential set, but <em>packages</em> have been removed from
1034 the Essential set when the functionality moved to a
1035 different package. So depending on these packages <em>just
1036 in case</em> they stop being essential does way more harm
1043 Sometimes, a package requires another package to be installed
1044 <em>and</em> configured before it can be installed. In this
1045 case, you must specify a <tt>Pre-Depends</tt> entry for
1050 You should not specify a <tt>Pre-Depends</tt> entry for a
1051 package before this has been discussed on the
1052 <tt>debian-devel</tt> mailing list and a consensus about
1053 doing that has been reached.
1057 The format of the package interrelationship control fields is
1058 described in <ref id="relationships">.
1062 <sect id="virtual_pkg">
1063 <heading>Virtual packages</heading>
1066 Sometimes, there are several packages which offer
1067 more-or-less the same functionality. In this case, it's
1068 useful to define a <em>virtual package</em> whose name
1069 describes that common functionality. (The virtual
1070 packages only exist logically, not physically; that's why
1071 they are called <em>virtual</em>.) The packages with this
1072 particular function will then <em>provide</em> the virtual
1073 package. Thus, any other package requiring that function
1074 can simply depend on the virtual package without having to
1075 specify all possible packages individually.
1079 All packages should use virtual package names where
1080 appropriate, and arrange to create new ones if necessary.
1081 They should not use virtual package names (except privately,
1082 amongst a cooperating group of packages) unless they have
1083 been agreed upon and appear in the list of virtual package
1084 names. (See also <ref id="virtual">)
1088 The latest version of the authoritative list of virtual
1089 package names can be found in the <tt>debian-policy</tt> package.
1090 It is also available from the Debian web mirrors at
1091 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1092 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1096 The procedure for updating the list is described in the preface
1103 <heading>Base system</heading>
1106 The <tt>base system</tt> is a minimum subset of the Debian
1107 GNU/Linux system that is installed before everything else
1108 on a new system. Only very few packages are allowed to form
1109 part of the base system, in order to keep the required disk
1114 The base system consists of all those packages with priority
1115 <tt>required</tt> or <tt>important</tt>. Many of them will
1116 be tagged <tt>essential</tt> (see below).
1121 <heading>Essential packages</heading>
1124 Essential is defined as the minimal set of functionality that
1125 must be available and usable on the system at all times, even
1126 when packages are in an unconfigured (but unpacked) state.
1127 Packages are tagged <tt>essential</tt> for a system using the
1128 <tt>Essential</tt> control file field. The format of the
1129 <tt>Essential</tt> control field is described in <ref
1134 Since these packages cannot be easily removed (one has to
1135 specify an extra <em>force option</em> to
1136 <prgn>dpkg</prgn> to do so), this flag must not be used
1137 unless absolutely necessary. A shared library package
1138 must not be tagged <tt>essential</tt>; dependencies will
1139 prevent its premature removal, and we need to be able to
1140 remove it when it has been superseded.
1144 Since dpkg will not prevent upgrading of other packages
1145 while an <tt>essential</tt> package is in an unconfigured
1146 state, all <tt>essential</tt> packages must supply all of
1147 their core functionality even when unconfigured. If the
1148 package cannot satisfy this requirement it must not be
1149 tagged as essential, and any packages depending on this
1150 package must instead have explicit dependency fields as
1155 Maintainers should take great care in adding any programs,
1156 interfaces, or functionality to <tt>essential</tt> packages.
1157 Packages may assume that functionality provided by
1158 <tt>essential</tt> packages is always available without
1159 declaring explicit dependencies, which means that removing
1160 functionality from the Essential set is very difficult and is
1161 almost never done. Any capability added to an
1162 <tt>essential</tt> package therefore creates an obligation to
1163 support that capability as part of the Essential set in
1168 You must not tag any packages <tt>essential</tt> before
1169 this has been discussed on the <tt>debian-devel</tt>
1170 mailing list and a consensus about doing that has been
1175 <sect id="maintscripts">
1176 <heading>Maintainer Scripts</heading>
1179 The package installation scripts should avoid producing
1180 output which is unnecessary for the user to see and
1181 should rely on <prgn>dpkg</prgn> to stave off boredom on
1182 the part of a user installing many packages. This means,
1183 amongst other things, using the <tt>--quiet</tt> option on
1184 <prgn>install-info</prgn>.
1188 Errors which occur during the execution of an installation
1189 script must be checked and the installation must not
1190 continue after an error.
1194 Note that in general <ref id="scripts"> applies to package
1195 maintainer scripts, too.
1199 You should not use <prgn>dpkg-divert</prgn> on a file
1200 belonging to another package without consulting the
1201 maintainer of that package first.
1205 All packages which supply an instance of a common command
1206 name (or, in general, filename) should generally use
1207 <prgn>update-alternatives</prgn>, so that they may be
1208 installed together. If <prgn>update-alternatives</prgn>
1209 is not used, then each package must use
1210 <tt>Conflicts</tt> to ensure that other packages are
1211 de-installed. (In this case, it may be appropriate to
1212 specify a conflict against earlier versions of something
1213 that previously did not use
1214 <prgn>update-alternatives</prgn>; this is an exception to
1215 the usual rule that versioned conflicts should be
1219 <sect1 id="maintscriptprompt">
1220 <heading>Prompting in maintainer scripts</heading>
1222 Package maintainer scripts may prompt the user if
1223 necessary. Prompting must be done by communicating
1224 through a program, such as <prgn>debconf</prgn>, which
1225 conforms to the Debian Configuration Management
1226 Specification, version 2 or higher.
1230 Packages which are essential, or which are dependencies of
1231 essential packages, may fall back on another prompting method
1232 if no such interface is available when they are executed.
1236 The Debian Configuration Management Specification is included
1237 in the <file>debconf_specification</file> files in the
1238 <package>debian-policy</package> package.
1239 It is also available from the Debian web mirrors at
1240 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1241 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1245 Packages which use the Debian Configuration Management
1246 Specification may contain an additional
1247 <prgn>config</prgn> script and a <tt>templates</tt>
1248 file in their control archive<footnote>
1249 The control.tar.gz inside the .deb.
1250 See <manref name="deb" section="5">.
1252 The <prgn>config</prgn> script might be run before the
1253 <prgn>preinst</prgn> script, and before the package is unpacked
1254 or any of its dependencies or pre-dependencies are satisfied.
1255 Therefore it must work using only the tools present in
1256 <em>essential</em> packages.<footnote>
1257 <package>Debconf</package> or another tool that
1258 implements the Debian Configuration Management
1259 Specification will also be installed, and any
1260 versioned dependencies on it will be satisfied
1261 before preconfiguration begins.
1266 Packages which use the Debian Configuration Management
1267 Specification must allow for translation of their user-visible
1268 messages by using a gettext-based system such as the one
1269 provided by the <package>po-debconf</package> package.
1273 Packages should try to minimize the amount of prompting
1274 they need to do, and they should ensure that the user
1275 will only ever be asked each question once. This means
1276 that packages should try to use appropriate shared
1277 configuration files (such as <file>/etc/papersize</file> and
1278 <file>/etc/news/server</file>), and shared
1279 <package>debconf</package> variables rather than each
1280 prompting for their own list of required pieces of
1285 It also means that an upgrade should not ask the same
1286 questions again, unless the user has used
1287 <tt>dpkg --purge</tt> to remove the package's configuration.
1288 The answers to configuration questions should be stored in an
1289 appropriate place in <file>/etc</file> so that the user can
1290 modify them, and how this has been done should be
1295 If a package has a vitally important piece of
1296 information to pass to the user (such as "don't run me
1297 as I am, you must edit the following configuration files
1298 first or you risk your system emitting badly-formatted
1299 messages"), it should display this in the
1300 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1301 prompt the user to hit return to acknowledge the
1302 message. Copyright messages do not count as vitally
1303 important (they belong in
1304 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1305 neither do instructions on how to use a program (these
1306 should be in on-line documentation, where all the users
1311 Any necessary prompting should almost always be confined
1312 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1313 script. If it is done in the <prgn>postinst</prgn>, it
1314 should be protected with a conditional so that
1315 unnecessary prompting doesn't happen if a package's
1316 installation fails and the <prgn>postinst</prgn> is
1317 called with <tt>abort-upgrade</tt>,
1318 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1328 <heading>Source packages</heading>
1330 <sect id="standardsversion">
1331 <heading>Standards conformance</heading>
1334 Source packages should specify the most recent version number
1335 of this policy document with which your package complied
1336 when it was last updated.
1340 This information may be used to file bug reports
1341 automatically if your package becomes too much out of date.
1345 The version is specified in the <tt>Standards-Version</tt>
1347 The format of the <tt>Standards-Version</tt> field is
1348 described in <ref id="f-Standards-Version">.
1352 You should regularly, and especially if your package has
1353 become out of date, check for the newest Policy Manual
1354 available and update your package, if necessary. When your
1355 package complies with the new standards you should update the
1356 <tt>Standards-Version</tt> source package field and
1357 release it.<footnote>
1358 See the file <file>upgrading-checklist</file> for
1359 information about policy which has changed between
1360 different versions of this document.
1366 <sect id="pkg-relations">
1367 <heading>Package relationships</heading>
1370 Source packages should specify which binary packages they
1371 require to be installed or not to be installed in order to
1372 build correctly. For example, if building a package
1373 requires a certain compiler, then the compiler should be
1374 specified as a build-time dependency.
1378 It is not necessary to explicitly specify build-time
1379 relationships on a minimal set of packages that are always
1380 needed to compile, link and put in a Debian package a
1381 standard "Hello World!" program written in C or C++. The
1382 required packages are called <em>build-essential</em>, and
1383 an informational list can be found in
1384 <file>/usr/share/doc/build-essential/list</file> (which is
1385 contained in the <tt>build-essential</tt>
1388 <list compact="compact">
1390 This allows maintaining the list separately
1391 from the policy documents (the list does not
1392 need the kind of control that the policy
1396 Having a separate package allows one to install
1397 the build-essential packages on a machine, as
1398 well as allowing other packages such as tasks to
1399 require installation of the build-essential
1400 packages using the depends relation.
1403 The separate package allows bug reports against
1404 the list to be categorized separately from
1405 the policy management process in the BTS.
1412 When specifying the set of build-time dependencies, one
1413 should list only those packages explicitly required by the
1414 build. It is not necessary to list packages which are
1415 required merely because some other package in the list of
1416 build-time dependencies depends on them.<footnote>
1417 The reason for this is that dependencies change, and
1418 you should list all those packages, and <em>only</em>
1419 those packages that <em>you</em> need directly. What
1420 others need is their business. For example, if you
1421 only link against <file>libimlib</file>, you will need to
1422 build-depend on <package>libimlib2-dev</package> but
1423 not against any <tt>libjpeg*</tt> packages, even
1424 though <tt>libimlib2-dev</tt> currently depends on
1425 them: installation of <package>libimlib2-dev</package>
1426 will automatically ensure that all of its run-time
1427 dependencies are satisfied.
1432 If build-time dependencies are specified, it must be
1433 possible to build the package and produce working binaries
1434 on a system with only essential and build-essential
1435 packages installed and also those required to satisfy the
1436 build-time relationships (including any implied
1437 relationships). In particular, this means that version
1438 clauses should be used rigorously in build-time
1439 relationships so that one cannot produce bad or
1440 inconsistently configured packages when the relationships
1441 are properly satisfied.
1445 <ref id="relationships"> explains the technical details.
1450 <heading>Changes to the upstream sources</heading>
1453 If changes to the source code are made that are not
1454 specific to the needs of the Debian system, they should be
1455 sent to the upstream authors in whatever form they prefer
1456 so as to be included in the upstream version of the
1461 If you need to configure the package differently for
1462 Debian or for Linux, and the upstream source doesn't
1463 provide a way to do so, you should add such configuration
1464 facilities (for example, a new <prgn>autoconf</prgn> test
1465 or <tt>#define</tt>) and send the patch to the upstream
1466 authors, with the default set to the way they originally
1467 had it. You can then easily override the default in your
1468 <file>debian/rules</file> or wherever is appropriate.
1472 You should make sure that the <prgn>configure</prgn> utility
1473 detects the correct architecture specification string
1474 (refer to <ref id="arch-spec"> for details).
1478 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1479 <prgn>configure</prgn> scripts are used, you should edit the
1480 <file>.in</file> files rather than editing the
1481 <prgn>Makefile</prgn> directly. This allows the user to
1482 reconfigure the package if necessary. You should
1483 <em>not</em> configure the package and edit the generated
1484 <prgn>Makefile</prgn>! This makes it impossible for someone
1485 else to later reconfigure the package without losing the
1491 <sect id="dpkgchangelog">
1492 <heading>Debian changelog: <file>debian/changelog</file></heading>
1495 Changes in the Debian version of the package should be
1496 briefly explained in the Debian changelog file
1497 <file>debian/changelog</file>.<footnote>
1499 Mistakes in changelogs are usually best rectified by
1500 making a new changelog entry rather than "rewriting
1501 history" by editing old changelog entries.
1504 This includes modifications
1505 made in the Debian package compared to the upstream one
1506 as well as other changes and updates to the package.
1508 Although there is nothing stopping an author who is also
1509 the Debian maintainer from using this changelog for all
1510 their changes, it will have to be renamed if the Debian
1511 and upstream maintainers become different people. In such
1512 a case, however, it might be better to maintain the package
1513 as a non-native package.
1518 The format of the <file>debian/changelog</file> allows the
1519 package building tools to discover which version of the package
1520 is being built and find out other release-specific information.
1524 That format is a series of entries like this:
1526 <example compact="compact">
1527 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1529 [optional blank line(s), stripped]
1531 * <var>change details</var>
1532 <var>more change details</var>
1534 [blank line(s), included in output of dpkg-parsechangelog]
1536 * <var>even more change details</var>
1538 [optional blank line(s), stripped]
1540 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1545 <var>package</var> and <var>version</var> are the source
1546 package name and version number.
1550 <var>distribution(s)</var> lists the distributions where
1551 this version should be installed when it is uploaded - it
1552 is copied to the <tt>Distribution</tt> field in the
1553 <file>.changes</file> file. See <ref id="f-Distribution">.
1557 <var>urgency</var> is the value for the <tt>Urgency</tt>
1558 field in the <file>.changes</file> file for the upload
1559 (see <ref id="f-Urgency">). It is not possible to specify
1560 an urgency containing commas; commas are used to separate
1561 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1562 <prgn>dpkg</prgn> changelog format (though there is
1563 currently only one useful <var>keyword</var>,
1568 The change details may in fact be any series of lines
1569 starting with at least two spaces, but conventionally each
1570 change starts with an asterisk and a separating space and
1571 continuation lines are indented so as to bring them in
1572 line with the start of the text above. Blank lines may be
1573 used here to separate groups of changes, if desired.
1577 If this upload resolves bugs recorded in the Bug Tracking
1578 System (BTS), they may be automatically closed on the
1579 inclusion of this package into the Debian archive by
1580 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1581 in the change details.<footnote>
1582 To be precise, the string should match the following
1583 Perl regular expression:
1585 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1587 Then all of the bug numbers listed will be closed by the
1588 archive maintenance script (<prgn>katie</prgn>) using the
1589 <var>version</var> of the changelog entry.
1591 This information is conveyed via the <tt>Closes</tt> field
1592 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1596 The maintainer name and email address used in the changelog
1597 should be the details of the person uploading <em>this</em>
1598 version. They are <em>not</em> necessarily those of the
1599 usual package maintainer. The information here will be
1600 copied to the <tt>Changed-By</tt> field in the
1601 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1602 and then later used to send an acknowledgement when the
1603 upload has been installed.
1607 The <var>date</var> must be in RFC822 format<footnote>
1608 This is generated by <tt>date -R</tt>.
1609 </footnote>; it must include the time zone specified
1610 numerically, with the time zone name or abbreviation
1611 optionally present as a comment in parentheses.
1615 The first "title" line with the package name must start
1616 at the left hand margin. The "trailer" line with the
1617 maintainer and date details must be preceded by exactly
1618 one space. The maintainer details and the date must be
1619 separated by exactly two spaces.
1623 The entire changelog must be encoded in UTF-8.
1627 For more information on placement of the changelog files
1628 within binary packages, please see <ref id="changelogs">.
1632 <sect id="dpkgcopyright">
1633 <heading>Copyright: <file>debian/copyright</file></heading>
1635 Every package must be accompanied by a verbatim copy of
1636 its copyright and distribution license in the file
1637 <file>/usr/share/doc/<var>package</var>/copyright</file>
1638 (see <ref id="copyrightfile"> for further details). Also see
1639 <ref id="pkgcopyright"> for further considerations relayed
1640 to copyrights for packages.
1644 <heading>Error trapping in makefiles</heading>
1647 When <prgn>make</prgn> invokes a command in a makefile
1648 (including your package's upstream makefiles and
1649 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1650 means that <prgn>sh</prgn>'s usual bad error handling
1651 properties apply: if you include a miniature script as one
1652 of the commands in your makefile you'll find that if you
1653 don't do anything about it then errors are not detected
1654 and <prgn>make</prgn> will blithely continue after
1659 Every time you put more than one shell command (this
1660 includes using a loop) in a makefile command you
1661 must make sure that errors are trapped. For
1662 simple compound commands, such as changing directory and
1663 then running a program, using <tt>&&</tt> rather
1664 than semicolon as a command separator is sufficient. For
1665 more complex commands including most loops and
1666 conditionals you should include a separate <tt>set -e</tt>
1667 command at the start of every makefile command that's
1668 actually one of these miniature shell scripts.
1672 <sect id="timestamps">
1673 <heading>Time Stamps</heading>
1675 Maintainers should preserve the modification times of the
1676 upstream source files in a package, as far as is reasonably
1678 The rationale is that there is some information conveyed
1679 by knowing the age of the file, for example, you could
1680 recognize that some documentation is very old by looking
1681 at the modification time, so it would be nice if the
1682 modification time of the upstream source would be
1688 <sect id="restrictions">
1689 <heading>Restrictions on objects in source packages</heading>
1692 The source package may not contain any hard links<footnote>
1694 This is not currently detected when building source
1695 packages, but only when extracting
1699 Hard links may be permitted at some point in the
1700 future, but would require a fair amount of
1703 </footnote>, device special files, sockets or setuid or
1704 setgid files.<footnote>
1705 Setgid directories are allowed.
1710 <sect id="debianrules">
1711 <heading>Main building script: <file>debian/rules</file></heading>
1714 This file must be an executable makefile, and contains the
1715 package-specific recipes for compiling the package and
1716 building binary package(s) from the source.
1720 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1721 so that it can be invoked by saying its name rather than
1722 invoking <prgn>make</prgn> explicitly.
1726 Since an interactive <file>debian/rules</file> script makes it
1727 impossible to auto-compile that package and also makes it
1728 hard for other people to reproduce the same binary
1729 package, all <em>required targets</em> MUST be
1730 non-interactive. At a minimum, required targets are the
1731 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1732 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1733 <em>binary-indep</em>, and <em>build</em>. It also follows
1734 that any target that these targets depend on must also be
1739 The targets are as follows (required unless stated otherwise):
1741 <tag><tt>build</tt></tag>
1744 The <tt>build</tt> target should perform all the
1745 configuration and compilation of the package.
1746 If a package has an interactive pre-build
1747 configuration routine, the Debianized source package
1748 must either be built after this has taken place (so
1749 that the binary package can be built without rerunning
1750 the configuration) or the configuration routine
1751 modified to become non-interactive. (The latter is
1752 preferable if there are architecture-specific features
1753 detected by the configuration routine.)
1757 For some packages, notably ones where the same
1758 source tree is compiled in different ways to produce
1759 two binary packages, the <tt>build</tt> target
1760 does not make much sense. For these packages it is
1761 good enough to provide two (or more) targets
1762 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1763 for each of the ways of building the package, and a
1764 <tt>build</tt> target that does nothing. The
1765 <tt>binary</tt> target will have to build the
1766 package in each of the possible ways and make the
1767 binary package out of each.
1771 The <tt>build</tt> target must not do anything
1772 that might require root privilege.
1776 The <tt>build</tt> target may need to run the
1777 <tt>clean</tt> target first - see below.
1781 When a package has a configuration and build routine
1782 which takes a long time, or when the makefiles are
1783 poorly designed, or when <tt>build</tt> needs to
1784 run <tt>clean</tt> first, it is a good idea to
1785 <tt>touch build</tt> when the build process is
1786 complete. This will ensure that if <tt>debian/rules
1787 build</tt> is run again it will not rebuild the whole
1789 Another common way to do this is for <tt>build</tt>
1790 to depend on <prgn>build-stamp</prgn> and to do
1791 nothing else, and for the <prgn>build-stamp</prgn>
1792 target to do the building and to <tt>touch
1793 build-stamp</tt> on completion. This is
1794 especially useful if the build routine creates a
1795 file or directory called <tt>build</tt>; in such a
1796 case, <tt>build</tt> will need to be listed as
1797 a phony target (i.e., as a dependency of the
1798 <tt>.PHONY</tt> target). See the documentation of
1799 <prgn>make</prgn> for more information on phony
1805 <tag><tt>build-arch</tt> (optional),
1806 <tt>build-indep</tt> (optional)
1810 A package may also provide both of the targets
1811 <tt>build-arch</tt> and <tt>build-indep</tt>.
1812 The <tt>build-arch</tt> target, if provided, should
1813 perform all the configuration and compilation required
1814 for producing all architecture-dependant binary packages
1815 (those packages for which the body of the
1816 <tt>Architecture</tt> field in <tt>debian/control</tt>
1817 is not <tt>all</tt>).
1818 Similarly, the <tt>build-indep</tt> target, if
1819 provided, should perform all the configuration and
1820 compilation required for producing all
1821 architecture-independent binary packages
1822 (those packages for which the body of the
1823 <tt>Architecture</tt> field in <tt>debian/control</tt>
1825 The <tt>build</tt> target should depend on those of the
1826 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1827 are provided in the rules file.
1831 If one or both of the targets <tt>build-arch</tt> and
1832 <tt>build-indep</tt> are not provided, then invoking
1833 <file>debian/rules</file> with one of the not-provided
1834 targets as arguments should produce a exit status code
1835 of 2. Usually this is provided automatically by make
1836 if the target is missing.
1840 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1841 must not do anything that might require root privilege.
1845 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1846 <tt>binary-indep</tt>
1850 The <tt>binary</tt> target must be all that is
1851 necessary for the user to build the binary package(s)
1852 produced from this source package. It is
1853 split into two parts: <prgn>binary-arch</prgn> builds
1854 the binary packages which are specific to a particular
1855 architecture, and <tt>binary-indep</tt> builds
1856 those which are not.
1859 <tt>binary</tt> may be (and commonly is) a target with
1860 no commands which simply depends on
1861 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1864 Both <tt>binary-*</tt> targets should depend on the
1865 <tt>build</tt> target, or on the appropriate
1866 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1867 provided, so that the package is built if it has not
1868 been already. It should then create the relevant
1869 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1870 make their control files and <prgn>dpkg-deb</prgn> to
1871 build them and place them in the parent of the top
1876 Both the <tt>binary-arch</tt> and
1877 <tt>binary-indep</tt> targets <em>must</em> exist.
1878 If one of them has nothing to do (which will always be
1879 the case if the source generates only a single binary
1880 package, whether architecture-dependent or not), it
1881 must still exist and must always succeed.
1885 The <tt>binary</tt> targets must be invoked as
1887 The <prgn>fakeroot</prgn> package often allows one
1888 to build a package correctly even without being
1894 <tag><tt>clean</tt></tag>
1897 This must undo any effects that the <tt>build</tt>
1898 and <tt>binary</tt> targets may have had, except
1899 that it should leave alone any output files created in
1900 the parent directory by a run of a <tt>binary</tt>
1905 If a <tt>build</tt> file is touched at the end of
1906 the <tt>build</tt> target, as suggested above, it
1907 should be removed as the first action that
1908 <tt>clean</tt> performs, so that running
1909 <tt>build</tt> again after an interrupted
1910 <tt>clean</tt> doesn't think that everything is
1915 The <tt>clean</tt> target may need to be
1916 invoked as root if <tt>binary</tt> has been
1917 invoked since the last <tt>clean</tt>, or if
1918 <tt>build</tt> has been invoked as root (since
1919 <tt>build</tt> may create directories, for
1924 <tag><tt>get-orig-source</tt> (optional)</tag>
1927 This target fetches the most recent version of the
1928 original source package from a canonical archive site
1929 (via FTP or WWW, for example), does any necessary
1930 rearrangement to turn it into the original source
1931 tar file format described below, and leaves it in the
1936 This target may be invoked in any directory, and
1937 should take care to clean up any temporary files it
1942 This target is optional, but providing it if
1943 possible is a good idea.
1947 <tag><tt>patch</tt> (optional)</tag>
1950 This target performs whatever additional actions are
1951 required to make the source ready for editing (unpacking
1952 additional upstream archives, applying patches, etc.).
1953 It is recommended to be implemented for any package where
1954 <tt>dpkg-source -x</tt> does not result in source ready
1955 for additional modification. See
1956 <ref id="readmesource">.
1962 The <tt>build</tt>, <tt>binary</tt> and
1963 <tt>clean</tt> targets must be invoked with the current
1964 directory being the package's top-level directory.
1969 Additional targets may exist in <file>debian/rules</file>,
1970 either as published or undocumented interfaces or for the
1971 package's internal use.
1975 The architectures we build on and build for are determined
1976 by <prgn>make</prgn> variables using the utility
1977 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1978 You can determine the
1979 Debian architecture and the GNU style architecture
1980 specification string for the build machine (the machine type
1981 we are building on) as well as for the host machine (the
1982 machine type we are building for). Here is a list of
1983 supported <prgn>make</prgn> variables:
1984 <list compact="compact">
1986 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1989 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
1992 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
1995 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1996 specification string)
1999 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2000 <tt>DEB_*_GNU_TYPE</tt>)
2003 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2004 <tt>DEB_*_GNU_TYPE</tt>)
2006 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2007 the build machine or <tt>HOST</tt> for specification of the
2012 Backward compatibility can be provided in the rules file
2013 by setting the needed variables to suitable default
2014 values; please refer to the documentation of
2015 <prgn>dpkg-architecture</prgn> for details.
2019 It is important to understand that the <tt>DEB_*_ARCH</tt>
2020 string only determines which Debian architecture we are
2021 building on or for. It should not be used to get the CPU
2022 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2023 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2024 GNU style variables should generally only be used with upstream
2028 <sect1 id="debianrules-options">
2029 <heading><file>debian/rules</file> and
2030 <tt>DEB_BUILD_OPTIONS</tt></heading>
2033 Supporting the standardized environment variable
2034 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2035 contain several flags to change how a package is compiled and
2036 built. Each flag must be in the form <var>flag</var> or
2037 <var>flag</var>=<var>options</var>. If multiple flags are
2038 given, they must be separated by whitespace.<footnote>
2039 Some packages support any delimiter, but whitespace is the
2040 easiest to parse inside a makefile and avoids ambiguity with
2041 flag values that contain commas.
2043 <var>flag</var> must start with a lowercase letter
2044 (<tt>a-z</tt>) and consist only of lowercase letters,
2045 numbers (<tt>0-9</tt>), and the characters
2046 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2047 <var>options</var> must not contain whitespace. The same
2048 tag should not be given multiple times with conflicting
2049 values. Package maintainers may assume that
2050 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2054 The meaning of the following tags has been standardized:
2058 This tag says to not run any build-time test suite
2059 provided by the package.
2063 The presence of this tag means that the package should
2064 be compiled with a minimum of optimization. For C
2065 programs, it is best to add <tt>-O0</tt> to
2066 <tt>CFLAGS</tt> (although this is usually the default).
2067 Some programs might fail to build or run at this level
2068 of optimization; it may be necessary to use
2069 <tt>-O1</tt>, for example.
2073 This tag means that the debugging symbols should not be
2074 stripped from the binary during installation, so that
2075 debugging information may be included in the package.
2077 <tag>parallel=n</tag>
2079 This tag means that the package should be built using up
2080 to <tt>n</tt> parallel processes if the package build
2081 system supports this.<footnote>
2082 Packages built with <tt>make</tt> can often implement
2083 this by passing the <tt>-j</tt><var>n</var> option to
2086 If the package build system does not support parallel
2087 builds, this string must be ignored. If the package
2088 build system only supports a lower level of concurrency
2089 than <var>n</var>, the package should be built using as
2090 many parallel processes as the package build system
2091 supports. It is up to the package maintainer to decide
2092 whether the package build times are long enough and the
2093 package build system is robust enough to make supporting
2094 parallel builds worthwhile.
2100 Unknown flags must be ignored by <file>debian/rules</file>.
2104 The following makefile snippet is an example of how one may
2105 implement the build options; you will probably have to
2106 massage this example in order to make it work for your
2108 <example compact="compact">
2111 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2112 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2113 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2114 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2116 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2121 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2122 INSTALL_PROGRAM += -s
2124 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2125 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2126 MAKEFLAGS += -j$(NUMJOBS)
2131 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2132 # Code to run the package test suite.
2139 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2140 <sect id="substvars">
2141 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2144 When <prgn>dpkg-gencontrol</prgn>,
2145 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2146 generate control files they perform variable substitutions
2147 on their output just before writing it. Variable
2148 substitutions have the form <tt>${<var>variable</var>}</tt>.
2149 The optional file <file>debian/substvars</file> contains
2150 variable substitutions to be used; variables can also be set
2151 directly from <file>debian/rules</file> using the <tt>-V</tt>
2152 option to the source packaging commands, and certain
2153 predefined variables are also available.
2157 The <file>debian/substvars</file> file is usually generated and
2158 modified dynamically by <file>debian/rules</file> targets, in
2159 which case it must be removed by the <tt>clean</tt> target.
2163 See <manref name="deb-substvars" section="5"> for full
2164 details about source variable substitutions, including the
2165 format of <file>debian/substvars</file>.</p>
2168 <sect id="debianwatch">
2169 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2172 This is an optional, recommended control file for the
2173 <tt>uscan</tt> utility which defines how to automatically
2174 scan ftp or http sites for newly available updates of the
2175 package. This is used by <url id="
2176 http://dehs.alioth.debian.org/"> and other Debian QA tools
2177 to help with quality control and maintenance of the
2178 distribution as a whole.
2183 <sect id="debianfiles">
2184 <heading>Generated files list: <file>debian/files</file></heading>
2187 This file is not a permanent part of the source tree; it
2188 is used while building packages to record which files are
2189 being generated. <prgn>dpkg-genchanges</prgn> uses it
2190 when it generates a <file>.changes</file> file.
2194 It should not exist in a shipped source package, and so it
2195 (and any backup files or temporary files such as
2196 <file>files.new</file><footnote>
2197 <file>files.new</file> is used as a temporary file by
2198 <prgn>dpkg-gencontrol</prgn> and
2199 <prgn>dpkg-distaddfile</prgn> - they write a new
2200 version of <tt>files</tt> here before renaming it,
2201 to avoid leaving a corrupted copy if an error
2203 </footnote>) should be removed by the
2204 <tt>clean</tt> target. It may also be wise to
2205 ensure a fresh start by emptying or removing it at the
2206 start of the <tt>binary</tt> target.
2210 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2211 package, it adds an entry to <file>debian/files</file> for the
2212 <file>.deb</file> file that will be created when <tt>dpkg-deb
2213 --build</tt> is run for that binary package. So for most
2214 packages all that needs to be done with this file is to
2215 delete it in the <tt>clean</tt> target.
2219 If a package upload includes files besides the source
2220 package and any binary packages whose control files were
2221 made with <prgn>dpkg-gencontrol</prgn> then they should be
2222 placed in the parent of the package's top-level directory
2223 and <prgn>dpkg-distaddfile</prgn> should be called to add
2224 the file to the list in <file>debian/files</file>.</p>
2227 <sect id="embeddedfiles">
2228 <heading>Convenience copies of code</heading>
2231 Some software packages include in their distribution convenience
2232 copies of code from other software packages, generally so that
2233 users compiling from source don't have to download multiple
2234 packages. Debian packages should not make use of these
2235 convenience copies unless the included package is explicitly
2236 intended to be used in this way.<footnote>
2237 For example, parts of the GNU build system work like this.
2239 If the included code is already in the Debian archive in the
2240 form of a library, the Debian packaging should ensure that
2241 binary packages reference the libraries already in Debian and
2242 the convenience copy is not used. If the included code is not
2243 already in Debian, it should be packaged separately as a
2244 prerequisite if possible.
2246 Having multiple copies of the same code in Debian is
2247 inefficient, often creates either static linking or shared
2248 library conflicts, and, most importantly, increases the
2249 difficulty of handling security vulnerabilities in the
2255 <sect id="readmesource">
2256 <heading>Source package handling:
2257 <file>debian/README.source</file></heading>
2260 If running <prgn>dpkg-source -x</prgn> on a source package
2261 doesn't produce the source of the package, ready for editing,
2262 and allow one to make changes and run
2263 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2264 without taking any additional steps, creating a
2265 <file>debian/README.source</file> documentation file is
2266 recommended. This file should explain how to do all of the
2269 <item>Generate the fully patched source, in a form ready for
2270 editing, that would be built to create Debian
2271 packages. Doing this with a <tt>patch</tt> target in
2272 <file>debian/rules</file> is recommended; see
2273 <ref id="debianrules">.</item>
2274 <item>Modify the source and save those modifications so that
2275 they will be applied when building the package.</item>
2276 <item>Remove source modifications that are currently being
2277 applied when building the package.</item>
2278 <item>Optionally, document what steps are necessary to
2279 upgrade the Debian source package to a new upstream version,
2280 if applicable.</item>
2282 This explanation should include specific commands and mention
2283 any additional required Debian packages. It should not assume
2284 familiarity with any specific Debian packaging system or patch
2289 This explanation may refer to a documentation file installed by
2290 one of the package's build dependencies provided that the
2291 referenced documentation clearly explains these tasks and is not
2292 a general reference manual.
2296 <file>debian/README.source</file> may also include any other
2297 information that would be helpful to someone modifying the
2298 source package. Even if the package doesn't fit the above
2299 description, maintainers are encouraged to document in a
2300 <file>debian/README.source</file> file any source package with a
2301 particularly complex or unintuitive source layout or build
2302 system (for example, a package that builds the same source
2303 multiple times to generate different binary packages).
2309 <chapt id="controlfields">
2310 <heading>Control files and their fields</heading>
2313 The package management system manipulates data represented in
2314 a common format, known as <em>control data</em>, stored in
2315 <em>control files</em>.
2316 Control files are used for source packages, binary packages and
2317 the <file>.changes</file> files which control the installation
2318 of uploaded files<footnote>
2319 <prgn>dpkg</prgn>'s internal databases are in a similar
2324 <sect id="controlsyntax">
2325 <heading>Syntax of control files</heading>
2328 A control file consists of one or more paragraphs of
2330 The paragraphs are also sometimes referred to as stanzas.
2332 The paragraphs are separated by blank lines. Some control
2333 files allow only one paragraph; others allow several, in
2334 which case each paragraph usually refers to a different
2335 package. (For example, in source packages, the first
2336 paragraph refers to the source package, and later paragraphs
2337 refer to binary packages generated from the source.)
2341 Each paragraph consists of a series of data fields; each
2342 field consists of the field name, followed by a colon and
2343 then the data/value associated with that field. It ends at
2344 the end of the (logical) line. Horizontal whitespace
2345 (spaces and tabs) may occur immediately before or after the
2346 value and is ignored there; it is conventional to put a
2347 single space after the colon. For example, a field might
2349 <example compact="compact">
2352 the field name is <tt>Package</tt> and the field value
2357 Many fields' values may span several lines; in this case
2358 each continuation line must start with a space or a tab.
2359 Any trailing spaces or tabs at the end of individual
2360 lines of a field value are ignored.
2364 In fields where it is specified that lines may not wrap,
2365 only a single line of data is allowed and whitespace is not
2366 significant in a field body. Whitespace must not appear
2367 inside names (of packages, architectures, files or anything
2368 else) or version numbers, or between the characters of
2369 multi-character version relationships.
2373 Field names are not case-sensitive, but it is usual to
2374 capitalize the field names using mixed case as shown below.
2378 Blank lines, or lines consisting only of spaces and tabs,
2379 are not allowed within field values or between fields - that
2380 would mean a new paragraph.
2384 All control files must be encoded in UTF-8.
2388 <sect id="sourcecontrolfiles">
2389 <heading>Source package control files -- <file>debian/control</file></heading>
2392 The <file>debian/control</file> file contains the most vital
2393 (and version-independent) information about the source package
2394 and about the binary packages it creates.
2398 The first paragraph of the control file contains information about
2399 the source package in general. The subsequent sets each describe a
2400 binary package that the source tree builds.
2404 The fields in the general paragraph (the first one, for the source
2407 <list compact="compact">
2408 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2409 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2410 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2411 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2412 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2413 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2414 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2415 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2420 The fields in the binary package paragraphs are:
2422 <list compact="compact">
2423 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2424 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2425 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2426 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2427 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2428 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2429 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2430 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2435 The syntax and semantics of the fields are described below.
2441 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2442 generate control files for binary packages (see below), by
2443 <prgn>dpkg-genchanges</prgn> to generate the
2444 <tt>.changes</tt> file to accompany the upload, and by
2445 <prgn>dpkg-source</prgn> when it creates the
2446 <file>.dsc</file> source control file as part of a source
2447 archive. Many fields are permitted to span multiple lines in
2448 <file>debian/control</file> but not in any other control
2449 file. These tools are responsible for removing the line
2450 breaks from such fields when using fields from
2451 <file>debian/control</file> to generate other control files.
2455 The fields here may contain variable references - their
2456 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2457 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2458 when they generate output control files.
2459 See <ref id="substvars"> for details.
2463 In addition to the control file syntax described <qref
2464 id="controlsyntax">above</qref>, this file may also contain
2465 comment lines starting with <tt>#</tt> without any preceding
2466 whitespace. All such lines are ignored, even in the middle of
2467 continuation lines for a multiline field, and do not end a
2473 <sect id="binarycontrolfiles">
2474 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2477 The <file>DEBIAN/control</file> file contains the most vital
2478 (and version-dependent) information about a binary package.
2482 The fields in this file are:
2484 <list compact="compact">
2485 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2486 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2487 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2488 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2489 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2490 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2491 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2492 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2493 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2494 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2495 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2496 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2501 <sect id="debiansourcecontrolfiles">
2502 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2505 This file contains a series of fields, identified and
2506 separated just like the fields in the control file of
2507 a binary package. The fields are listed below; their
2508 syntax is described above, in <ref id="pkg-controlfields">.
2510 <list compact="compact">
2511 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2512 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2513 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2514 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2515 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2516 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2517 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2518 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2519 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2520 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2526 The source package control file is generated by
2527 <prgn>dpkg-source</prgn> when it builds the source
2528 archive, from other files in the source package,
2529 described above. When unpacking, it is checked against
2530 the files and directories in the other parts of the
2536 <sect id="debianchangesfiles">
2537 <heading>Debian changes files -- <file>.changes</file></heading>
2540 The .changes files are used by the Debian archive maintenance
2541 software to process updates to packages. They contain one
2542 paragraph which contains information from the
2543 <tt>debian/control</tt> file and other data about the
2544 source package gathered via <tt>debian/changelog</tt>
2545 and <tt>debian/rules</tt>.
2549 The fields in this file are:
2551 <list compact="compact">
2552 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2553 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2554 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2555 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2556 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2557 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2558 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2559 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2560 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2561 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2562 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2563 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2564 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2570 <sect id="controlfieldslist">
2571 <heading>List of fields</heading>
2573 <sect1 id="f-Source">
2574 <heading><tt>Source</tt></heading>
2577 This field identifies the source package name.
2581 In <file>debian/control</file> or a <file>.dsc</file> file,
2582 this field must contain only the name of the source package.
2586 In a binary package control file or a <file>.changes</file>
2587 file, the source package name may be followed by a version
2588 number in parentheses<footnote>
2589 It is customary to leave a space after the package name
2590 if a version number is specified.
2592 This version number may be omitted (and is, by
2593 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2594 the <tt>Version</tt> field of the binary package in
2595 question. The field itself may be omitted from a binary
2596 package control file when the source package has the same
2597 name and version as the binary package.
2601 Package names must consist only of lower case letters
2602 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2603 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2604 They must be at least two characters long and must start
2605 with an alphanumeric character.
2609 <sect1 id="f-Maintainer">
2610 <heading><tt>Maintainer</tt></heading>
2613 The package maintainer's name and email address. The name
2614 should come first, then the email address inside angle
2615 brackets <tt><></tt> (in RFC822 format).
2619 If the maintainer's name contains a full stop then the
2620 whole field will not work directly as an email address due
2621 to a misfeature in the syntax specified in RFC822; a
2622 program using this field as an address must check for this
2623 and correct the problem if necessary (for example by
2624 putting the name in round brackets and moving it to the
2625 end, and bringing the email address forward).
2629 <sect1 id="f-Uploaders">
2630 <heading><tt>Uploaders</tt></heading>
2633 List of the names and email addresses of co-maintainers of
2634 the package, if any. If the package has other maintainers
2635 beside the one named in the
2636 <qref id="f-Maintainer">Maintainer field</qref>, their
2637 names and email addresses should be listed here. The
2638 format is the same as that of the Maintainer tag, and
2639 multiple entries should be comma separated. Currently,
2640 this field is restricted to a single line of data. This
2641 is an optional field.
2644 Any parser that interprets the Uploaders field in
2645 <file>debian/control</file> must permit it to span multiple
2646 lines. Line breaks in an Uploaders field that spans multiple
2647 lines are not significant and the semantics of the field are
2648 the same as if the line breaks had not been present.
2652 <sect1 id="f-Changed-By">
2653 <heading><tt>Changed-By</tt></heading>
2656 The name and email address of the person who changed the
2657 said package. Usually the name of the maintainer.
2658 All the rules for the Maintainer field apply here, too.
2662 <sect1 id="f-Section">
2663 <heading><tt>Section</tt></heading>
2666 This field specifies an application area into which the package
2667 has been classified. See <ref id="subsections">.
2671 When it appears in the <file>debian/control</file> file,
2672 it gives the value for the subfield of the same name in
2673 the <tt>Files</tt> field of the <file>.changes</file> file.
2674 It also gives the default for the same field in the binary
2679 <sect1 id="f-Priority">
2680 <heading><tt>Priority</tt></heading>
2683 This field represents how important that it is that the user
2684 have the package installed. See <ref id="priorities">.
2688 When it appears in the <file>debian/control</file> file,
2689 it gives the value for the subfield of the same name in
2690 the <tt>Files</tt> field of the <file>.changes</file> file.
2691 It also gives the default for the same field in the binary
2696 <sect1 id="f-Package">
2697 <heading><tt>Package</tt></heading>
2700 The name of the binary package.
2704 Package names must consist only of lower case letters
2705 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2706 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2707 They must be at least two characters long and must start
2708 with an alphanumeric character.
2712 <sect1 id="f-Architecture">
2713 <heading><tt>Architecture</tt></heading>
2716 Depending on context and the control file used, the
2717 <tt>Architecture</tt> field can include the following sets of
2720 <item>A unique single word identifying a Debian machine
2721 architecture as described in <ref id="arch-spec">.
2722 <item><tt>all</tt>, which indicates an
2723 architecture-independent package.
2724 <item><tt>any</tt>, which indicates a package available
2725 for building on any architecture.
2726 <item><tt>source</tt>, which indicates a source package.
2731 In the main <file>debian/control</file> file in the source
2732 package, this field may contain the special value
2733 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2734 architectures separated by spaces. If <tt>any</tt> or
2735 <tt>all</tt> appear, they must be the entire contents of the
2736 field. Most packages will use either <tt>any</tt> or
2737 <tt>all</tt>. Specifying a specific list of architectures is
2738 for the minority of cases where a program is not portable or
2739 is not useful on some architectures, and where possible the
2740 program should be made portable instead.
2744 In the source package control file <file>.dsc</file>, this
2745 field may contain either the special value <tt>any</tt> or a
2746 list of architectures separated by spaces. If a list is given,
2747 it may include (or consist solely of) the special value
2748 <tt>all</tt>. In other words, in <file>.dsc</file> files
2749 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2750 in combination with specific architectures. The
2751 <tt>Architecture</tt> field in the source package control file
2752 <file>.dsc</file> is generally constructed from the
2753 <tt>Architecture</tt> fields in the
2754 <file>debian/control</file> in the source package.
2758 Specifying <tt>any</tt> indicates that the source package
2759 isn't dependent on any particular architecture and should
2760 compile fine on any one. The produced binary package(s)
2761 will either be specific to whatever the current build
2762 architecture is or will be architecture-independent.
2766 Specifying only <tt>all</tt> indicates that the source package
2767 will only build architecture-independent packages. If this is
2768 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2769 <tt>any</tt> implies that the source package will build at
2770 least one architecture-dependent package.
2774 Specifying a list of architectures indicates that the source
2775 will build an architecture-dependent package, and will only
2776 work correctly on the listed architectures. If the source
2777 package also builds at least one architecture-independent
2778 package, <tt>all</tt> will also be included in the list.
2782 In a <file>.changes</file> file, the <tt>Architecture</tt>
2783 field lists the architecture(s) of the package(s)
2784 currently being uploaded. This will be a list; if the
2785 source for the package is also being uploaded, the special
2786 entry <tt>source</tt> is also present. <tt>all</tt> will be
2787 present if any architecture-independent packages are being
2788 uploaded. <tt>any</tt> may never occur in the
2789 <tt>Architecture</tt> field in the <file>.changes</file>
2794 See <ref id="debianrules"> for information how to get the
2795 architecture for the build process.
2799 <sect1 id="f-Essential">
2800 <heading><tt>Essential</tt></heading>
2803 This is a boolean field which may occur only in the
2804 control file of a binary package or in a per-package fields
2805 paragraph of a main source control data file.
2809 If set to <tt>yes</tt> then the package management system
2810 will refuse to remove the package (upgrading and replacing
2811 it is still possible). The other possible value is <tt>no</tt>,
2812 which is the same as not having the field at all.
2817 <heading>Package interrelationship fields:
2818 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2819 <tt>Recommends</tt>, <tt>Suggests</tt>,
2820 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2821 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2825 These fields describe the package's relationships with
2826 other packages. Their syntax and semantics are described
2827 in <ref id="relationships">.</p>
2830 <sect1 id="f-Standards-Version">
2831 <heading><tt>Standards-Version</tt></heading>
2834 The most recent version of the standards (the policy
2835 manual and associated texts) with which the package
2840 The version number has four components: major and minor
2841 version number and major and minor patch level. When the
2842 standards change in a way that requires every package to
2843 change the major number will be changed. Significant
2844 changes that will require work in many packages will be
2845 signaled by a change to the minor number. The major patch
2846 level will be changed for any change to the meaning of the
2847 standards, however small; the minor patch level will be
2848 changed when only cosmetic, typographical or other edits
2849 are made which neither change the meaning of the document
2850 nor affect the contents of packages.
2854 Thus only the first three components of the policy version
2855 are significant in the <em>Standards-Version</em> control
2856 field, and so either these three components or the all
2857 four components may be specified.<footnote>
2858 In the past, people specified the full version number
2859 in the Standards-Version field, for example "2.3.0.0".
2860 Since minor patch-level changes don't introduce new
2861 policy, it was thought it would be better to relax
2862 policy and only require the first 3 components to be
2863 specified, in this example "2.3.0". All four
2864 components may still be used if someone wishes to do so.
2870 <sect1 id="f-Version">
2871 <heading><tt>Version</tt></heading>
2874 The version number of a package. The format is:
2875 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2879 The three components here are:
2881 <tag><var>epoch</var></tag>
2884 This is a single (generally small) unsigned integer. It
2885 may be omitted, in which case zero is assumed. If it is
2886 omitted then the <var>upstream_version</var> may not
2891 It is provided to allow mistakes in the version numbers
2892 of older versions of a package, and also a package's
2893 previous version numbering schemes, to be left behind.
2897 <tag><var>upstream_version</var></tag>
2900 This is the main part of the version number. It is
2901 usually the version number of the original ("upstream")
2902 package from which the <file>.deb</file> file has been made,
2903 if this is applicable. Usually this will be in the same
2904 format as that specified by the upstream author(s);
2905 however, it may need to be reformatted to fit into the
2906 package management system's format and comparison
2911 The comparison behavior of the package management system
2912 with respect to the <var>upstream_version</var> is
2913 described below. The <var>upstream_version</var>
2914 portion of the version number is mandatory.
2918 The <var>upstream_version</var> may contain only
2919 alphanumerics<footnote>
2920 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2922 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2923 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2924 tilde) and should start with a digit. If there is no
2925 <var>debian_revision</var> then hyphens are not allowed;
2926 if there is no <var>epoch</var> then colons are not
2931 <tag><var>debian_revision</var></tag>
2934 This part of the version number specifies the version of
2935 the Debian package based on the upstream version. It
2936 may contain only alphanumerics and the characters
2937 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2938 tilde) and is compared in the same way as the
2939 <var>upstream_version</var> is.
2943 It is optional; if it isn't present then the
2944 <var>upstream_version</var> may not contain a hyphen.
2945 This format represents the case where a piece of
2946 software was written specifically to be turned into a
2947 Debian package, and so there is only one "debianisation"
2948 of it and therefore no revision indication is required.
2952 It is conventional to restart the
2953 <var>debian_revision</var> at <tt>1</tt> each time the
2954 <var>upstream_version</var> is increased.
2958 The package management system will break the version
2959 number apart at the last hyphen in the string (if there
2960 is one) to determine the <var>upstream_version</var> and
2961 <var>debian_revision</var>. The absence of a
2962 <var>debian_revision</var> is equivalent to a
2963 <var>debian_revision</var> of <tt>0</tt>.
2970 When comparing two version numbers, first the <var>epoch</var>
2971 of each are compared, then the <var>upstream_version</var> if
2972 <var>epoch</var> is equal, and then <var>debian_revision</var>
2973 if <var>upstream_version</var> is also equal.
2974 <var>epoch</var> is compared numerically. The
2975 <var>upstream_version</var> and <var>debian_revision</var>
2976 parts are compared by the package management system using the
2977 following algorithm:
2981 The strings are compared from left to right.
2985 First the initial part of each string consisting entirely of
2986 non-digit characters is determined. These two parts (one of
2987 which may be empty) are compared lexically. If a difference
2988 is found it is returned. The lexical comparison is a
2989 comparison of ASCII values modified so that all the letters
2990 sort earlier than all the non-letters and so that a tilde
2991 sorts before anything, even the end of a part. For example,
2992 the following parts are in sorted order from earliest to
2993 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
2994 <tt>a</tt>.<footnote>
2995 One common use of <tt>~</tt> is for upstream pre-releases.
2996 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
2997 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3002 Then the initial part of the remainder of each string which
3003 consists entirely of digit characters is determined. The
3004 numerical values of these two parts are compared, and any
3005 difference found is returned as the result of the comparison.
3006 For these purposes an empty string (which can only occur at
3007 the end of one or both version strings being compared) counts
3012 These two steps (comparing and removing initial non-digit
3013 strings and initial digit strings) are repeated until a
3014 difference is found or both strings are exhausted.
3018 Note that the purpose of epochs is to allow us to leave behind
3019 mistakes in version numbering, and to cope with situations
3020 where the version numbering scheme changes. It is
3021 <em>not</em> intended to cope with version numbers containing
3022 strings of letters which the package management system cannot
3023 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3024 silly orderings (the author of this manual has heard of a
3025 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3026 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3027 <tt>2</tt> and so forth).
3031 <sect1 id="f-Description">
3032 <heading><tt>Description</tt></heading>
3035 In a source or binary control file, the <tt>Description</tt>
3036 field contains a description of the binary package, consisting
3037 of two parts, the synopsis or the short description, and the
3038 long description. The field's format is as follows:
3043 Description: <single line synopsis>
3044 <extended description over several lines>
3049 The lines in the extended description can have these formats:
3055 Those starting with a single space are part of a paragraph.
3056 Successive lines of this form will be word-wrapped when
3057 displayed. The leading space will usually be stripped off.
3061 Those starting with two or more spaces. These will be
3062 displayed verbatim. If the display cannot be panned
3063 horizontally, the displaying program will line wrap them "hard"
3064 (i.e., without taking account of word breaks). If it can they
3065 will be allowed to trail off to the right. None, one or two
3066 initial spaces may be deleted, but the number of spaces
3067 deleted from each line will be the same (so that you can have
3068 indenting work correctly, for example).
3072 Those containing a single space followed by a single full stop
3073 character. These are rendered as blank lines. This is the
3074 <em>only</em> way to get a blank line<footnote>
3075 Completely empty lines will not be rendered as blank lines.
3076 Instead, they will cause the parser to think you're starting
3077 a whole new record in the control file, and will therefore
3078 likely abort with an error.
3083 Those containing a space, a full stop and some more characters.
3084 These are for future expansion. Do not use them.
3090 Do not use tab characters. Their effect is not predictable.
3094 See <ref id="descriptions"> for further information on this.
3098 In a <file>.changes</file> file, the <tt>Description</tt> field
3099 contains a summary of the descriptions for the packages being
3104 The part of the field before the first newline is empty;
3105 thereafter each line has the name of a binary package and
3106 the summary description line from that binary package.
3107 Each line is indented by one space.
3112 <sect1 id="f-Distribution">
3113 <heading><tt>Distribution</tt></heading>
3116 In a <file>.changes</file> file or parsed changelog output
3117 this contains the (space-separated) name(s) of the
3118 distribution(s) where this version of the package should
3119 be installed. Valid distributions are determined by the
3120 archive maintainers.<footnote>
3121 Example distribution names in the Debian archive used in
3122 <file>.changes</file> files are:
3123 <taglist compact="compact">
3124 <tag><em>unstable</em></tag>
3126 This distribution value refers to the
3127 <em>developmental</em> part of the Debian distribution
3128 tree. Most new packages, new upstream versions of
3129 packages and bug fixes go into the <em>unstable</em>
3133 <tag><em>experimental</em></tag>
3135 The packages with this distribution value are deemed
3136 by their maintainers to be high risk. Oftentimes they
3137 represent early beta or developmental packages from
3138 various sources that the maintainers want people to
3139 try, but are not ready to be a part of the other parts
3140 of the Debian distribution tree.
3145 Others are used for updating stable releases or for
3146 security uploads. More information is available in the
3147 Debian Developer's Reference, section "The Debian
3151 The Debian archive software only supports listing a single
3152 distribution. Migration of packages to other distributions is
3153 handled outside of the upload process.
3158 <heading><tt>Date</tt></heading>
3161 This field includes the date the package was built or last edited.
3165 The value of this field is usually extracted from the
3166 <file>debian/changelog</file> file - see
3167 <ref id="dpkgchangelog">).
3171 <sect1 id="f-Format">
3172 <heading><tt>Format</tt></heading>
3175 This field specifies a format revision for the file.
3176 The most current format described in the Policy Manual
3177 is version <strong>1.5</strong>. The syntax of the
3178 format value is the same as that of a package version
3179 number except that no epoch or Debian revision is allowed
3180 - see <ref id="f-Version">.
3184 <sect1 id="f-Urgency">
3185 <heading><tt>Urgency</tt></heading>
3188 This is a description of how important it is to upgrade to
3189 this version from previous ones. It consists of a single
3190 keyword taking one of the values <tt>low</tt>,
3191 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3192 <tt>critical</tt><footnote>
3193 Other urgency values are supported with configuration
3194 changes in the archive software but are not used in Debian.
3195 The urgency affects how quickly a package will be considered
3196 for inclusion into the <tt>testing</tt> distribution and
3197 gives an indication of the importance of any fixes included
3198 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3199 treated as synonymous.
3200 </footnote> (not case-sensitive) followed by an optional
3201 commentary (separated by a space) which is usually in
3202 parentheses. For example:
3205 Urgency: low (HIGH for users of diversions)
3211 The value of this field is usually extracted from the
3212 <file>debian/changelog</file> file - see
3213 <ref id="dpkgchangelog">.
3217 <sect1 id="f-Changes">
3218 <heading><tt>Changes</tt></heading>
3221 This field contains the human-readable changes data, describing
3222 the differences between the last version and the current one.
3226 There should be nothing in this field before the first
3227 newline; all the subsequent lines must be indented by at
3228 least one space; blank lines must be represented by a line
3229 consisting only of a space and a full stop.
3233 The value of this field is usually extracted from the
3234 <file>debian/changelog</file> file - see
3235 <ref id="dpkgchangelog">).
3239 Each version's change information should be preceded by a
3240 "title" line giving at least the version, distribution(s)
3241 and urgency, in a human-readable way.
3245 If data from several versions is being returned the entry
3246 for the most recent version should be returned first, and
3247 entries should be separated by the representation of a
3248 blank line (the "title" line may also be followed by the
3249 representation of blank line).
3253 <sect1 id="f-Binary">
3254 <heading><tt>Binary</tt></heading>
3257 This field is a list of binary packages.
3261 When it appears in the <file>.dsc</file> file it is the list
3262 of binary packages which a source package can produce. It
3263 does not necessarily produce all of these binary packages
3264 for every architecture. The source control file doesn't
3265 contain details of which architectures are appropriate for
3266 which of the binary packages.
3270 When it appears in a <file>.changes</file> file it lists the
3271 names of the binary packages actually being uploaded.
3275 The syntax is a list of binary packages separated by
3277 A space after each comma is conventional.
3278 </footnote>. Currently the packages must be separated using
3279 only spaces in the <file>.changes</file> file.
3283 <sect1 id="f-Installed-Size">
3284 <heading><tt>Installed-Size</tt></heading>
3287 This field appears in the control files of binary
3288 packages, and in the <file>Packages</file> files. It gives
3289 the total amount of disk space required to install the
3294 The disk space is represented in kilobytes as a simple
3299 <sect1 id="f-Files">
3300 <heading><tt>Files</tt></heading>
3303 This field contains a list of files with information about
3304 each one. The exact information and syntax varies with
3305 the context. In all cases the part of the field
3306 contents on the same line as the field name is empty. The
3307 remainder of the field is one line per file, each line
3308 being indented by one space and containing a number of
3309 sub-fields separated by spaces.
3313 In the <file>.dsc</file> file, each line contains the MD5
3314 checksum, size and filename of the tar file and (if applicable)
3315 diff file which make up the remainder of the source
3317 That is, the parts which are not the <tt>.dsc</tt>.
3319 The exact forms of the filenames are described
3320 in <ref id="pkg-sourcearchives">.
3324 In the <file>.changes</file> file this contains one line per
3325 file being uploaded. Each line contains the MD5 checksum,
3326 size, section and priority and the filename.
3327 The <qref id="f-Section">section</qref>
3328 and <qref id="f-Priority">priority</qref>
3329 are the values of the corresponding fields in
3330 the main source control file. If no section or priority is
3331 specified then <tt>-</tt> should be used, though section
3332 and priority values must be specified for new packages to
3333 be installed properly.
3337 The special value <tt>byhand</tt> for the section in a
3338 <tt>.changes</tt> file indicates that the file in question
3339 is not an ordinary package file and must by installed by
3340 hand by the distribution maintainers. If the section is
3341 <tt>byhand</tt> the priority should be <tt>-</tt>.
3345 If a new Debian revision of a package is being shipped and
3346 no new original source archive is being distributed the
3347 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3348 entry for the original source archive
3349 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3350 but the <file>.changes</file> file should leave it out. In
3351 this case the original source archive on the distribution
3352 site must match exactly, byte-for-byte, the original
3353 source archive which was used to generate the
3354 <file>.dsc</file> file and diff which are being uploaded.</p>
3357 <sect1 id="f-Closes">
3358 <heading><tt>Closes</tt></heading>
3361 A space-separated list of bug report numbers that the upload
3362 governed by the .changes file closes.
3366 <sect1 id="f-Homepage">
3367 <heading><tt>Homepage</tt></heading>
3370 The URL of the web site for this package, preferably (when
3371 applicable) the site from which the original source can be
3372 obtained and any additional upstream documentation or
3373 information may be found. The content of this field is a
3374 simple URL without any surrounding characters such as
3382 <heading>User-defined fields</heading>
3385 Additional user-defined fields may be added to the
3386 source package control file. Such fields will be
3387 ignored, and not copied to (for example) binary or
3388 source package control files or upload control files.
3392 If you wish to add additional unsupported fields to
3393 these output files you should use the mechanism
3398 Fields in the main source control information file with
3399 names starting <tt>X</tt>, followed by one or more of
3400 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3401 be copied to the output files. Only the part of the
3402 field name after the hyphen will be used in the output
3403 file. Where the letter <tt>B</tt> is used the field
3404 will appear in binary package control files, where the
3405 letter <tt>S</tt> is used in source package control
3406 files and where <tt>C</tt> is used in upload control
3407 (<tt>.changes</tt>) files.
3411 For example, if the main source information control file
3414 XBS-Comment: I stand between the candle and the star.
3416 then the binary and source package control files will contain the
3419 Comment: I stand between the candle and the star.
3428 <chapt id="maintainerscripts">
3429 <heading>Package maintainer scripts and installation procedure</heading>
3432 <heading>Introduction to package maintainer scripts</heading>
3435 It is possible to supply scripts as part of a package which
3436 the package management system will run for you when your
3437 package is installed, upgraded or removed.
3441 These scripts are the files <prgn>preinst</prgn>,
3442 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3443 <prgn>postrm</prgn> in the control area of the package.
3444 They must be proper executable files; if they are scripts
3445 (which is recommended), they must start with the usual
3446 <tt>#!</tt> convention. They should be readable and
3447 executable by anyone, and must not be world-writable.
3451 The package management system looks at the exit status from
3452 these scripts. It is important that they exit with a
3453 non-zero status if there is an error, so that the package
3454 management system can stop its processing. For shell
3455 scripts this means that you <em>almost always</em> need to
3456 use <tt>set -e</tt> (this is usually true when writing shell
3457 scripts, in fact). It is also important, of course, that
3458 they exit with a zero status if everything went well.
3462 Additionally, packages interacting with users using
3463 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3464 install a <prgn>config</prgn> script in the control area,
3465 see <ref id="maintscriptprompt"> for details.
3469 When a package is upgraded a combination of the scripts from
3470 the old and new packages is called during the upgrade
3471 procedure. If your scripts are going to be at all
3472 complicated you need to be aware of this, and may need to
3473 check the arguments to your scripts.
3477 Broadly speaking the <prgn>preinst</prgn> is called before
3478 (a particular version of) a package is installed, and the
3479 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3480 before (a version of) a package is removed and the
3481 <prgn>postrm</prgn> afterwards.
3485 Programs called from maintainer scripts should not normally
3486 have a path prepended to them. Before installation is
3487 started, the package management system checks to see if the
3488 programs <prgn>ldconfig</prgn>,
3489 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3490 and <prgn>update-rc.d</prgn> can be found via the
3491 <tt>PATH</tt> environment variable. Those programs, and any
3492 other program that one would expect to be in the
3493 <tt>PATH</tt>, should thus be invoked without an absolute
3494 pathname. Maintainer scripts should also not reset the
3495 <tt>PATH</tt>, though they might choose to modify it by
3496 prepending or appending package-specific directories. These
3497 considerations really apply to all shell scripts.</p>
3500 <sect id="idempotency">
3501 <heading>Maintainer scripts idempotency</heading>
3504 It is necessary for the error recovery procedures that the
3505 scripts be idempotent. This means that if it is run
3506 successfully, and then it is called again, it doesn't bomb
3507 out or cause any harm, but just ensures that everything is
3508 the way it ought to be. If the first call failed, or
3509 aborted half way through for some reason, the second call
3510 should merely do the things that were left undone the first
3511 time, if any, and exit with a success status if everything
3513 This is so that if an error occurs, the user interrupts
3514 <prgn>dpkg</prgn> or some other unforeseen circumstance
3515 happens you don't leave the user with a badly-broken
3516 package when <prgn>dpkg</prgn> attempts to repeat the
3522 <sect id="controllingterminal">
3523 <heading>Controlling terminal for maintainer scripts</heading>
3526 The maintainer scripts are guaranteed to run with a
3527 controlling terminal and can interact with the user.
3528 Because these scripts may be executed with standard output
3529 redirected into a pipe for logging purposes, Perl scripts
3530 should set unbuffered output by setting <tt>$|=1</tt> so
3531 that the output is printed immediately rather than being
3535 <sect id="exitstatus">
3536 <heading>Exit status</heading>
3539 Each script must return a zero exit status for
3540 success, or a nonzero one for failure, since the package
3541 management system looks for the exit status of these scripts
3542 and determines what action to take next based on that datum.
3546 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3551 <list compact="compact">
3553 <var>new-preinst</var> <tt>install</tt>
3556 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3559 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3562 <var>old-preinst</var> <tt>abort-upgrade</tt>
3563 <var>new-version</var>
3568 <list compact="compact">
3570 <var>postinst</var> <tt>configure</tt>
3571 <var>most-recently-configured-version</var>
3574 <var>old-postinst</var> <tt>abort-upgrade</tt>
3575 <var>new-version</var>
3578 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3579 <tt>in-favour</tt> <var>package</var>
3580 <var>new-version</var>
3583 <var>postinst</var> <tt>abort-remove</tt>
3586 <var>deconfigured's-postinst</var>
3587 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3588 <var>failed-install-package</var> <var>version</var>
3589 [<tt>removing</tt> <var>conflicting-package</var>
3595 <list compact="compact">
3597 <var>prerm</var> <tt>remove</tt>
3600 <var>old-prerm</var> <tt>upgrade</tt>
3601 <var>new-version</var>
3604 <var>new-prerm</var> <tt>failed-upgrade</tt>
3605 <var>old-version</var>
3608 <var>conflictor's-prerm</var> <tt>remove</tt>
3609 <tt>in-favour</tt> <var>package</var>
3610 <var>new-version</var>
3613 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3614 <tt>in-favour</tt> <var>package-being-installed</var>
3615 <var>version</var> [<tt>removing</tt>
3616 <var>conflicting-package</var>
3622 <list compact="compact">
3624 <var>postrm</var> <tt>remove</tt>
3627 <var>postrm</var> <tt>purge</tt>
3630 <var>old-postrm</var> <tt>upgrade</tt>
3631 <var>new-version</var>
3634 <var>new-postrm</var> <tt>failed-upgrade</tt>
3635 <var>old-version</var>
3638 <var>new-postrm</var> <tt>abort-install</tt>
3641 <var>new-postrm</var> <tt>abort-install</tt>
3642 <var>old-version</var>
3645 <var>new-postrm</var> <tt>abort-upgrade</tt>
3646 <var>old-version</var>
3649 <var>disappearer's-postrm</var> <tt>disappear</tt>
3650 <var>overwriter</var>
3651 <var>overwriter-version</var>
3657 <sect id="unpackphase">
3658 <heading>Details of unpack phase of installation or upgrade</heading>
3661 The procedure on installation/upgrade/overwrite/disappear
3662 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3663 stage of <tt>dpkg --install</tt>) is as follows. In each
3664 case, if a major error occurs (unless listed below) the
3665 actions are, in general, run backwards - this means that the
3666 maintainer scripts are run with different arguments in
3667 reverse order. These are the "error unwind" calls listed
3674 If a version of the package is already installed, call
3675 <example compact="compact">
3676 <var>old-prerm</var> upgrade <var>new-version</var>
3680 If the script runs but exits with a non-zero
3681 exit status, <prgn>dpkg</prgn> will attempt:
3682 <example compact="compact">
3683 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3685 If this works, the upgrade continues. If this
3686 does not work, the error unwind:
3687 <example compact="compact">
3688 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3690 If this works, then the old-version is
3691 "Installed", if not, the old version is in a
3692 "Failed-Config" state.
3698 If a "conflicting" package is being removed at the same time,
3699 or if any package will be broken (due to <tt>Breaks</tt>):
3702 If <tt>--auto-deconfigure</tt> is
3703 specified, call, for each package to be deconfigured
3704 due to <tt>Breaks</tt>:
3705 <example compact="compact">
3706 <var>deconfigured's-prerm</var> deconfigure \
3707 in-favour <var>package-being-installed</var> <var>version</var>
3710 <example compact="compact">
3711 <var>deconfigured's-postinst</var> abort-deconfigure \
3712 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3714 The deconfigured packages are marked as
3715 requiring configuration, so that if
3716 <tt>--install</tt> is used they will be
3717 configured again if possible.
3720 If any packages depended on a conflicting
3721 package being removed and <tt>--auto-deconfigure</tt> is
3722 specified, call, for each such package:
3723 <example compact="compact">
3724 <var>deconfigured's-prerm</var> deconfigure \
3725 in-favour <var>package-being-installed</var> <var>version</var> \
3726 removing <var>conflicting-package</var> <var>version</var>
3729 <example compact="compact">
3730 <var>deconfigured's-postinst</var> abort-deconfigure \
3731 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3732 removing <var>conflicting-package</var> <var>version</var>
3734 The deconfigured packages are marked as
3735 requiring configuration, so that if
3736 <tt>--install</tt> is used they will be
3737 configured again if possible.
3740 To prepare for removal of each conflicting package, call:
3741 <example compact="compact">
3742 <var>conflictor's-prerm</var> remove \
3743 in-favour <var>package</var> <var>new-version</var>
3746 <example compact="compact">
3747 <var>conflictor's-postinst</var> abort-remove \
3748 in-favour <var>package</var> <var>new-version</var>
3757 If the package is being upgraded, call:
3758 <example compact="compact">
3759 <var>new-preinst</var> upgrade <var>old-version</var>
3761 If this fails, we call:
3763 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3770 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3772 is called. If this works, then the old version
3773 is in an "Installed" state, or else it is left
3774 in an "Unpacked" state.
3779 If it fails, then the old version is left
3780 in an "Half-Installed" state.
3787 Otherwise, if the package had some configuration
3788 files from a previous version installed (i.e., it
3789 is in the "configuration files only" state):
3790 <example compact="compact">
3791 <var>new-preinst</var> install <var>old-version</var>
3795 <var>new-postrm</var> abort-install <var>old-version</var>
3797 If this fails, the package is left in a
3798 "Half-Installed" state, which requires a
3799 reinstall. If it works, the packages is left in
3800 a "Config Files" state.
3803 Otherwise (i.e., the package was completely purged):
3804 <example compact="compact">
3805 <var>new-preinst</var> install
3808 <example compact="compact">
3809 <var>new-postrm</var> abort-install
3811 If the error-unwind fails, the package is in a
3812 "Half Installed" phase, and requires a
3813 reinstall. If the error unwind works, the
3814 package is in a not installed state.
3821 The new package's files are unpacked, overwriting any
3822 that may be on the system already, for example any
3823 from the old version of the same package or from
3824 another package. Backups of the old files are kept
3825 temporarily, and if anything goes wrong the package
3826 management system will attempt to put them back as
3827 part of the error unwind.
3831 It is an error for a package to contain files which
3832 are on the system in another package, unless
3833 <tt>Replaces</tt> is used (see <ref id="replaces">).
3835 The following paragraph is not currently the case:
3836 Currently the <tt>- - force-overwrite</tt> flag is
3837 enabled, downgrading it to a warning, but this may not
3843 It is a more serious error for a package to contain a
3844 plain file or other kind of non-directory where another
3845 package has a directory (again, unless
3846 <tt>Replaces</tt> is used). This error can be
3847 overridden if desired using
3848 <tt>--force-overwrite-dir</tt>, but this is not
3853 Packages which overwrite each other's files produce
3854 behavior which, though deterministic, is hard for the
3855 system administrator to understand. It can easily
3856 lead to "missing" programs if, for example, a package
3857 is installed which overwrites a file from another
3858 package, and is then removed again.<footnote>
3859 Part of the problem is due to what is arguably a
3860 bug in <prgn>dpkg</prgn>.
3865 A directory will never be replaced by a symbolic link
3866 to a directory or vice versa; instead, the existing
3867 state (symlink or not) will be left alone and
3868 <prgn>dpkg</prgn> will follow the symlink if there is
3877 If the package is being upgraded, call
3878 <example compact="compact">
3879 <var>old-postrm</var> upgrade <var>new-version</var>
3883 If this fails, <prgn>dpkg</prgn> will attempt:
3884 <example compact="compact">
3885 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3887 If this works, installation continues. If not,
3889 <example compact="compact">
3890 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3892 If this fails, the old version is left in an
3893 "Half Installed" state. If it works, dpkg now
3895 <example compact="compact">
3896 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3898 If this fails, the old version is left in an
3899 "Half Installed" state. If it works, dpkg now
3901 <example compact="compact">
3902 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3904 If this fails, the old version is in an
3911 This is the point of no return - if
3912 <prgn>dpkg</prgn> gets this far, it won't back off
3913 past this point if an error occurs. This will
3914 leave the package in a fairly bad state, which
3915 will require a successful re-installation to clear
3916 up, but it's when <prgn>dpkg</prgn> starts doing
3917 things that are irreversible.
3922 Any files which were in the old version of the package
3923 but not in the new are removed.
3927 The new file list replaces the old.
3931 The new maintainer scripts replace the old.
3935 Any packages all of whose files have been overwritten
3936 during the installation, and which aren't required for
3937 dependencies, are considered to have been removed.
3938 For each such package
3941 <prgn>dpkg</prgn> calls:
3942 <example compact="compact">
3943 <var>disappearer's-postrm</var> disappear \
3944 <var>overwriter</var> <var>overwriter-version</var>
3948 The package's maintainer scripts are removed.
3951 It is noted in the status database as being in a
3952 sane state, namely not installed (any conffiles
3953 it may have are ignored, rather than being
3954 removed by <prgn>dpkg</prgn>). Note that
3955 disappearing packages do not have their prerm
3956 called, because <prgn>dpkg</prgn> doesn't know
3957 in advance that the package is going to
3964 Any files in the package we're unpacking that are also
3965 listed in the file lists of other packages are removed
3966 from those lists. (This will lobotomize the file list
3967 of the "conflicting" package if there is one.)
3971 The backup files made during installation, above, are
3977 The new package's status is now sane, and recorded as
3982 Here is another point of no return - if the
3983 conflicting package's removal fails we do not unwind
3984 the rest of the installation; the conflicting package
3985 is left in a half-removed limbo.
3990 If there was a conflicting package we go and do the
3991 removal actions (described below), starting with the
3992 removal of the conflicting package's files (any that
3993 are also in the package being installed have already
3994 been removed from the conflicting package's file list,
3995 and so do not get removed now).
4001 <sect id="configdetails"><heading>Details of configuration</heading>
4004 When we configure a package (this happens with <tt>dpkg
4005 --install</tt> and <tt>dpkg --configure</tt>), we first
4006 update any <tt>conffile</tt>s and then call:
4007 <example compact="compact">
4008 <var>postinst</var> configure <var>most-recently-configured-version</var>
4013 No attempt is made to unwind after errors during
4014 configuration. If the configuration fails, the package is in
4015 a "Failed Config" state, and an error message is generated.
4019 If there is no most recently configured version
4020 <prgn>dpkg</prgn> will pass a null argument.
4023 Historical note: Truly ancient (pre-1997) versions of
4024 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4025 (including the angle brackets) in this case. Even older
4026 ones did not pass a second argument at all, under any
4027 circumstance. Note that upgrades using such an old dpkg
4028 version are unlikely to work for other reasons, even if
4029 this old argument behavior is handled by your postinst script.
4035 <sect id="removedetails"><heading>Details of removal and/or
4036 configuration purging</heading>
4042 <example compact="compact">
4043 <var>prerm</var> remove
4047 If prerm fails during replacement due to conflict
4049 <var>conflictor's-postinst</var> abort-remove \
4050 in-favour <var>package</var> <var>new-version</var>
4054 <var>postinst</var> abort-remove
4058 If this fails, the package is in a "Failed-Config"
4059 state, or else it remains "Installed".
4063 The package's files are removed (except <tt>conffile</tt>s).
4066 <example compact="compact">
4067 <var>postrm</var> remove
4071 If it fails, there's no error unwind, and the package is in
4072 an "Half-Installed" state.
4077 All the maintainer scripts except the <prgn>postrm</prgn>
4082 If we aren't purging the package we stop here. Note
4083 that packages which have no <prgn>postrm</prgn> and no
4084 <tt>conffile</tt>s are automatically purged when
4085 removed, as there is no difference except for the
4086 <prgn>dpkg</prgn> status.
4090 The <tt>conffile</tt>s and any backup files
4091 (<tt>~</tt>-files, <tt>#*#</tt> files,
4092 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4097 <example compact="compact">
4098 <var>postrm</var> purge
4102 If this fails, the package remains in a "Config-Files"
4107 The package's file list is removed.
4116 <chapt id="relationships">
4117 <heading>Declaring relationships between packages</heading>
4119 <sect id="depsyntax">
4120 <heading>Syntax of relationship fields</heading>
4123 These fields all have a uniform syntax. They are a list of
4124 package names separated by commas.
4128 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4129 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4130 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4131 control file fields of the package, which declare
4132 dependencies on other packages, the package names listed may
4133 also include lists of alternative package names, separated
4134 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4135 if any one of the alternative packages is installed, that
4136 part of the dependency is considered to be satisfied.
4140 All of the fields except for <tt>Provides</tt> may restrict
4141 their applicability to particular versions of each named
4142 package. This is done in parentheses after each individual
4143 package name; the parentheses should contain a relation from
4144 the list below followed by a version number, in the format
4145 described in <ref id="f-Version">.
4149 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4150 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4151 strictly earlier, earlier or equal, exactly equal, later or
4152 equal and strictly later, respectively. The deprecated
4153 forms <tt><</tt> and <tt>></tt> were used to mean
4154 earlier/later or equal, rather than strictly earlier/later,
4155 so they should not appear in new packages (though
4156 <prgn>dpkg</prgn> still supports them).
4160 Whitespace may appear at any point in the version
4161 specification subject to the rules in <ref
4162 id="controlsyntax">, and must appear where it's necessary to
4163 disambiguate; it is not otherwise significant. All of the
4164 relationship fields may span multiple lines. For
4165 consistency and in case of future changes to
4166 <prgn>dpkg</prgn> it is recommended that a single space be
4167 used after a version relationship and before a version
4168 number; it is also conventional to put a single space after
4169 each comma, on either side of each vertical bar, and before
4170 each open parenthesis. When wrapping a relationship field, it
4171 is conventional to do so after a comma and before the space
4172 following that comma.
4176 For example, a list of dependencies might appear as:
4177 <example compact="compact">
4180 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4185 All fields that specify build-time relationships
4186 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4187 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4188 may be restricted to a certain set of architectures. This
4189 is indicated in brackets after each individual package name and
4190 the optional version specification. The brackets enclose a
4191 list of Debian architecture names separated by whitespace.
4192 Exclamation marks may be prepended to each of the names.
4193 (It is not permitted for some names to be prepended with
4194 exclamation marks while others aren't.) If the current Debian
4195 host architecture is not in this list and there are no
4196 exclamation marks in the list, or it is in the list with a
4197 prepended exclamation mark, the package name and the
4198 associated version specification are ignored completely for
4199 the purposes of defining the relationships.
4204 <example compact="compact">
4206 Build-Depends-Indep: texinfo
4207 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4208 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4210 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4211 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4212 <tt>gnumach-dev</tt> only on hurd-i386.
4216 If the architecture-restricted dependency is part of a set of
4217 alternatives using <tt>|</tt>, that alternative is ignored
4218 completely on architectures that do not match the restriction.
4220 <example compact="compact">
4221 Build-Depends: foo [!i386] | bar [!amd64]
4223 is equivalent to <tt>bar</tt> on the i386 architecture, to
4224 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4225 bar</tt> on all other architectures.
4229 Note that the binary package relationship fields such as
4230 <tt>Depends</tt> appear in one of the binary package
4231 sections of the control file, whereas the build-time
4232 relationships such as <tt>Build-Depends</tt> appear in the
4233 source package section of the control file (which is the
4238 <sect id="binarydeps">
4239 <heading>Binary Dependencies - <tt>Depends</tt>,
4240 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4241 <tt>Pre-Depends</tt>
4245 Packages can declare in their control file that they have
4246 certain relationships to other packages - for example, that
4247 they may not be installed at the same time as certain other
4248 packages, and/or that they depend on the presence of others.
4252 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4253 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4254 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4255 <tt>Breaks</tt> is described in <ref id="breaks">, and
4256 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4257 rest are described below.
4261 These seven fields are used to declare a dependency
4262 relationship by one package on another. Except for
4263 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4264 depending (binary) package's control file.
4265 (<tt>Enhances</tt> appears in the recommending package's
4266 control file, and <tt>Breaks</tt> appears in the version of
4267 depended-on package which causes the named package to
4272 A <tt>Depends</tt> field takes effect <em>only</em> when a
4273 package is to be configured. It does not prevent a package
4274 being on the system in an unconfigured state while its
4275 dependencies are unsatisfied, and it is possible to replace
4276 a package whose dependencies are satisfied and which is
4277 properly installed with a different version whose
4278 dependencies are not and cannot be satisfied; when this is
4279 done the depending package will be left unconfigured (since
4280 attempts to configure it will give errors) and will not
4281 function properly. If it is necessary, a
4282 <tt>Pre-Depends</tt> field can be used, which has a partial
4283 effect even when a package is being unpacked, as explained
4284 in detail below. (The other three dependency fields,
4285 <tt>Recommends</tt>, <tt>Suggests</tt> and
4286 <tt>Enhances</tt>, are only used by the various front-ends
4287 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4288 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4292 For this reason packages in an installation run are usually
4293 all unpacked first and all configured later; this gives
4294 later versions of packages with dependencies on later
4295 versions of other packages the opportunity to have their
4296 dependencies satisfied.
4300 In case of circular dependencies, since installation or
4301 removal order honoring the dependency order can't be
4302 established, dependency loops are broken at some point
4303 (based on rules below), and some packages may not be able to
4304 rely on their dependencies being present when being
4305 installed or removed, depending on which side of the break
4306 of the circular dependency loop they happen to be on. If one
4307 of the packages in the loop has no postinst script, then the
4308 cycle will be broken at that package, so as to ensure that
4309 all postinst scripts run with the dependencies properly
4310 configured if this is possible. Otherwise the breaking point
4315 The <tt>Depends</tt> field thus allows package maintainers
4316 to impose an order in which packages should be configured.
4320 The meaning of the five dependency fields is as follows:
4322 <tag><tt>Depends</tt></tag>
4325 This declares an absolute dependency. A package will
4326 not be configured unless all of the packages listed in
4327 its <tt>Depends</tt> field have been correctly
4332 The <tt>Depends</tt> field should be used if the
4333 depended-on package is required for the depending
4334 package to provide a significant amount of
4339 The <tt>Depends</tt> field should also be used if the
4340 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4341 <prgn>postrm</prgn> scripts require the package to be
4342 present in order to run. Note, however, that the
4343 <prgn>postrm</prgn> cannot rely on any non-essential
4344 packages to be present during the <tt>purge</tt>
4348 <tag><tt>Recommends</tt></tag>
4351 This declares a strong, but not absolute, dependency.
4355 The <tt>Recommends</tt> field should list packages
4356 that would be found together with this one in all but
4357 unusual installations.
4361 <tag><tt>Suggests</tt></tag>
4363 This is used to declare that one package may be more
4364 useful with one or more others. Using this field
4365 tells the packaging system and the user that the
4366 listed packages are related to this one and can
4367 perhaps enhance its usefulness, but that installing
4368 this one without them is perfectly reasonable.
4371 <tag><tt>Enhances</tt></tag>
4373 This field is similar to Suggests but works in the
4374 opposite direction. It is used to declare that a
4375 package can enhance the functionality of another
4379 <tag><tt>Pre-Depends</tt></tag>
4382 This field is like <tt>Depends</tt>, except that it
4383 also forces <prgn>dpkg</prgn> to complete installation
4384 of the packages named before even starting the
4385 installation of the package which declares the
4386 pre-dependency, as follows:
4390 When a package declaring a pre-dependency is about to
4391 be <em>unpacked</em> the pre-dependency can be
4392 satisfied if the depended-on package is either fully
4393 configured, <em>or even if</em> the depended-on
4394 package(s) are only unpacked or half-configured,
4395 provided that they have been configured correctly at
4396 some point in the past (and not removed or partially
4397 removed since). In this case, both the
4398 previously-configured and currently unpacked or
4399 half-configured versions must satisfy any version
4400 clause in the <tt>Pre-Depends</tt> field.
4404 When the package declaring a pre-dependency is about
4405 to be <em>configured</em>, the pre-dependency will be
4406 treated as a normal <tt>Depends</tt>, that is, it will
4407 be considered satisfied only if the depended-on
4408 package has been correctly configured.
4412 <tt>Pre-Depends</tt> should be used sparingly,
4413 preferably only by packages whose premature upgrade or
4414 installation would hamper the ability of the system to
4415 continue with any upgrade that might be in progress.
4419 <tt>Pre-Depends</tt> are also required if the
4420 <prgn>preinst</prgn> script depends on the named
4421 package. It is best to avoid this situation if
4429 When selecting which level of dependency to use you should
4430 consider how important the depended-on package is to the
4431 functionality of the one declaring the dependency. Some
4432 packages are composed of components of varying degrees of
4433 importance. Such a package should list using
4434 <tt>Depends</tt> the package(s) which are required by the
4435 more important components. The other components'
4436 requirements may be mentioned as Suggestions or
4437 Recommendations, as appropriate to the components' relative
4443 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4446 When one binary package declares that it breaks another,
4447 <prgn>dpkg</prgn> will refuse to allow the package which
4448 declares <tt>Breaks</tt> be installed unless the broken
4449 package is deconfigured first, and it will refuse to
4450 allow the broken package to be reconfigured.
4454 A package will not be regarded as causing breakage merely
4455 because its configuration files are still installed; it must
4456 be at least half-installed.
4460 A special exception is made for packages which declare that
4461 they break their own package name or a virtual package which
4462 they provide (see below): this does not count as a real
4467 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4468 version clause; such a <tt>Breaks</tt> is introduced in the
4469 version of an (implicit or explicit) dependency which
4470 violates an assumption or reveals a bug in earlier versions
4471 of the broken package. This use of <tt>Breaks</tt> will
4472 inform higher-level package management tools that broken
4473 package must be upgraded before the new one.
4477 If the breaking package also overwrites some files from the
4478 older package, it should use <tt>Replaces</tt> (not
4479 <tt>Conflicts</tt>) to ensure this goes smoothly.
4483 <sect id="conflicts">
4484 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4487 When one binary package declares a conflict with another
4488 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4489 refuse to allow them to be installed on the system at the
4494 If one package is to be installed, the other must be removed
4495 first - if the package being installed is marked as
4496 replacing (see <ref id="replaces">) the one on the system,
4497 or the one on the system is marked as deselected, or both
4498 packages are marked <tt>Essential</tt>, then
4499 <prgn>dpkg</prgn> will automatically remove the package
4500 which is causing the conflict, otherwise it will halt the
4501 installation of the new package with an error. This
4502 mechanism is specifically designed to produce an error when
4503 the installed package is <tt>Essential</tt>, but the new
4508 A package will not cause a conflict merely because its
4509 configuration files are still installed; it must be at least
4514 A special exception is made for packages which declare a
4515 conflict with their own package name, or with a virtual
4516 package which they provide (see below): this does not
4517 prevent their installation, and allows a package to conflict
4518 with others providing a replacement for it. You use this
4519 feature when you want the package in question to be the only
4520 package providing some feature.
4524 A <tt>Conflicts</tt> entry should almost never have an
4525 "earlier than" version clause. This would prevent
4526 <prgn>dpkg</prgn> from upgrading or installing the package
4527 which declared such a conflict until the upgrade or removal
4528 of the conflicted-with package had been completed. Instead,
4529 <tt>Breaks</tt> may be used.
4533 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4537 As well as the names of actual ("concrete") packages, the
4538 package relationship fields <tt>Depends</tt>,
4539 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4540 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4541 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4542 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4543 may mention "virtual packages".
4547 A <em>virtual package</em> is one which appears in the
4548 <tt>Provides</tt> control file field of another package.
4549 The effect is as if the package(s) which provide a
4550 particular virtual package name had been listed by name
4551 everywhere the virtual package name appears. (See also <ref
4556 If there are both concrete and virtual packages of the same
4557 name, then the dependency may be satisfied (or the conflict
4558 caused) by either the concrete package with the name in
4559 question or any other concrete package which provides the
4560 virtual package with the name in question. This is so that,
4561 for example, supposing we have
4562 <example compact="compact">
4565 </example> and someone else releases an enhanced version of
4566 the <tt>bar</tt> package they can say:
4567 <example compact="compact">
4571 and the <tt>bar-plus</tt> package will now also satisfy the
4572 dependency for the <tt>foo</tt> package.
4576 If a relationship field has a version number attached
4577 then only real packages will be considered to see whether
4578 the relationship is satisfied (or the prohibition violated,
4579 for a conflict or breakage) - it is assumed that a real
4580 package which provides the virtual package is not of the
4581 "right" version. So, a <tt>Provides</tt> field may not
4582 contain version numbers, and the version number of the
4583 concrete package which provides a particular virtual package
4584 will not be looked at when considering a dependency on or
4585 conflict with the virtual package name.
4589 It is likely that the ability will be added in a future
4590 release of <prgn>dpkg</prgn> to specify a version number for
4591 each virtual package it provides. This feature is not yet
4592 present, however, and is expected to be used only
4597 If you want to specify which of a set of real packages
4598 should be the default to satisfy a particular dependency on
4599 a virtual package, you should list the real package as an
4600 alternative before the virtual one.
4605 <sect id="replaces"><heading>Overwriting files and replacing
4606 packages - <tt>Replaces</tt></heading>
4609 Packages can declare in their control file that they should
4610 overwrite files in certain other packages, or completely
4611 replace other packages. The <tt>Replaces</tt> control file
4612 field has these two distinct purposes.
4615 <sect1><heading>Overwriting files in other packages</heading>
4618 Firstly, as mentioned before, it is usually an error for a
4619 package to contain files which are on the system in
4624 However, if the overwriting package declares that it
4625 <tt>Replaces</tt> the one containing the file being
4626 overwritten, then <prgn>dpkg</prgn> will replace the file
4627 from the old package with that from the new. The file
4628 will no longer be listed as "owned" by the old package.
4632 If a package is completely replaced in this way, so that
4633 <prgn>dpkg</prgn> does not know of any files it still
4634 contains, it is considered to have "disappeared". It will
4635 be marked as not wanted on the system (selected for
4636 removal) and not installed. Any <tt>conffile</tt>s
4637 details noted for the package will be ignored, as they
4638 will have been taken over by the overwriting package. The
4639 package's <prgn>postrm</prgn> script will be run with a
4640 special argument to allow the package to do any final
4641 cleanup required. See <ref id="mscriptsinstact">.
4644 Replaces is a one way relationship -- you have to
4645 install the replacing package after the replaced
4652 For this usage of <tt>Replaces</tt>, virtual packages (see
4653 <ref id="virtual">) are not considered when looking at a
4654 <tt>Replaces</tt> field - the packages declared as being
4655 replaced must be mentioned by their real names.
4659 Furthermore, this usage of <tt>Replaces</tt> only takes
4660 effect when both packages are at least partially on the
4661 system at once, so that it can only happen if they do not
4662 conflict or if the conflict has been overridden.
4667 <sect1><heading>Replacing whole packages, forcing their
4671 Secondly, <tt>Replaces</tt> allows the packaging system to
4672 resolve which package should be removed when there is a
4673 conflict - see <ref id="conflicts">. This usage only
4674 takes effect when the two packages <em>do</em> conflict,
4675 so that the two usages of this field do not interfere with
4680 In this situation, the package declared as being replaced
4681 can be a virtual package, so for example, all mail
4682 transport agents (MTAs) would have the following fields in
4683 their control files:
4684 <example compact="compact">
4685 Provides: mail-transport-agent
4686 Conflicts: mail-transport-agent
4687 Replaces: mail-transport-agent
4689 ensuring that only one MTA can be installed at any one
4694 <sect id="sourcebinarydeps">
4695 <heading>Relationships between source and binary packages -
4696 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4697 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4701 Source packages that require certain binary packages to be
4702 installed or absent at the time of building the package
4703 can declare relationships to those binary packages.
4707 This is done using the <tt>Build-Depends</tt>,
4708 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4709 <tt>Build-Conflicts-Indep</tt> control file fields.
4713 Build-dependencies on "build-essential" binary packages can be
4714 omitted. Please see <ref id="pkg-relations"> for more information.
4718 The dependencies and conflicts they define must be satisfied
4719 (as defined earlier for binary packages) in order to invoke
4720 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4722 If you make "build-arch" or "binary-arch", you need
4723 Build-Depends. If you make "build-indep" or
4724 "binary-indep", you need Build-Depends and
4725 Build-Depends-Indep. If you make "build" or "binary",
4729 There is no Build-Depends-Arch; this role is essentially
4730 met with Build-Depends. Anyone building the
4731 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4732 is basically assumed to be building the whole package
4733 anyway and so installs all build dependencies. The
4734 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4735 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4736 does not yet know how to check for its existence) and
4737 <tt>binary-arch</tt>.
4740 The purpose of the original split, I recall, was so that
4741 the autobuilders wouldn't need to install extra packages
4742 needed only for the binary-indep targets. But without a
4743 build-arch/build-indep split, this didn't work, since
4744 most of the work is done in the build target, not in the
4750 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4752 The <tt>Build-Depends</tt> and
4753 <tt>Build-Conflicts</tt> fields must be satisfied when
4754 any of the following targets is invoked:
4755 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4756 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4757 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4759 <tag><tt>Build-Depends-Indep</tt>,
4760 <tt>Build-Conflicts-Indep</tt></tag>
4762 The <tt>Build-Depends-Indep</tt> and
4763 <tt>Build-Conflicts-Indep</tt> fields must be
4764 satisfied when any of the following targets is
4765 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4766 <tt>binary</tt> and <tt>binary-indep</tt>.
4776 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4779 Packages containing shared libraries must be constructed with
4780 a little care to make sure that the shared library is always
4781 available. This is especially important for packages whose
4782 shared libraries are vitally important, such as the C library
4783 (currently <tt>libc6</tt>).
4787 Packages involving shared libraries should be split up into
4788 several binary packages. This section mostly deals with how
4789 this separation is to be accomplished; rules for files within
4790 the shared library packages are in <ref id="libraries"> instead.
4793 <sect id="sharedlibs-runtime">
4794 <heading>Run-time shared libraries</heading>
4797 The run-time shared library needs to be placed in a package
4798 whose name changes whenever the shared object version
4801 Since it is common place to install several versions of a
4802 package that just provides shared libraries, it is a
4803 good idea that the library package should not
4804 contain any extraneous non-versioned files, unless they
4805 happen to be in versioned directories.</p>
4807 The most common mechanism is to place it in a package
4809 <package><var>libraryname</var><var>soversion</var></package>,
4810 where <file><var>soversion</var></file> is the version number
4811 in the soname of the shared library<footnote>
4812 The soname is the shared object name: it's the thing
4813 that has to match exactly between building an executable
4814 and running it for the dynamic linker to be able run the
4815 program. For example, if the soname of the library is
4816 <file>libfoo.so.6</file>, the library package would be
4817 called <file>libfoo6</file>.
4819 Alternatively, if it would be confusing to directly append
4820 <var>soversion</var> to <var>libraryname</var> (e.g. because
4821 <var>libraryname</var> itself ends in a number), you may use
4822 <package><var>libraryname</var>-<var>soversion</var></package> and
4823 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4828 If you have several shared libraries built from the same
4829 source tree you may lump them all together into a single
4830 shared library package, provided that you change all of
4831 their sonames at once (so that you don't get filename
4832 clashes if you try to install different versions of the
4833 combined shared libraries package).
4837 The package should install the shared libraries under
4838 their normal names. For example, the <package>libgdbm3</package>
4839 package should install <file>libgdbm.so.3.0.0</file> as
4840 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4841 renamed or re-linked by any <prgn>prerm</prgn> or
4842 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4843 of renaming things safely without affecting running programs,
4844 and attempts to interfere with this are likely to lead to
4849 Shared libraries should not be installed executable, since
4850 the dynamic linker does not require this and trying to
4851 execute a shared library usually results in a core dump.
4855 The run-time library package should include the symbolic link that
4856 <prgn>ldconfig</prgn> would create for the shared libraries.
4857 For example, the <package>libgdbm3</package> package should include
4858 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4859 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4860 linker (for example <prgn>ld.so</prgn> or
4861 <prgn>ld-linux.so.*</prgn>) can find the library between the
4862 time that <prgn>dpkg</prgn> installs it and the time that
4863 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4865 The package management system requires the library to be
4866 placed before the symbolic link pointing to it in the
4867 <file>.deb</file> file. This is so that when
4868 <prgn>dpkg</prgn> comes to install the symlink
4869 (overwriting the previous symlink pointing at an older
4870 version of the library), the new shared library is already
4871 in place. In the past, this was achieved by creating the
4872 library in the temporary packaging directory before
4873 creating the symlink. Unfortunately, this was not always
4874 effective, since the building of the tar file in the
4875 <file>.deb</file> depended on the behavior of the underlying
4876 file system. Some file systems (such as reiserfs) reorder
4877 the files so that the order of creation is forgotten.
4878 Since version 1.7.0, <prgn>dpkg</prgn>
4879 reorders the files itself as necessary when building a
4880 package. Thus it is no longer important to concern
4881 oneself with the order of file creation.
4885 <sect1 id="ldconfig">
4886 <heading><tt>ldconfig</tt></heading>
4889 Any package installing shared libraries in one of the default
4890 library directories of the dynamic linker (which are currently
4891 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4892 listed in <file>/etc/ld.so.conf</file><footnote>
4894 <list compact="compact">
4895 <item>/usr/local/lib</item>
4896 <item>/usr/lib/libc5-compat</item>
4897 <item>/lib/libc5-compat</item>
4900 must use <prgn>ldconfig</prgn> to update the shared library
4905 The package maintainer scripts must only call
4906 <prgn>ldconfig</prgn> under these circumstances:
4907 <list compact="compact">
4908 <item>When the <prgn>postinst</prgn> script is run with a
4909 first argument of <tt>configure</tt>, the script must call
4910 <prgn>ldconfig</prgn>, and may optionally invoke
4911 <prgn>ldconfig</prgn> at other times.
4913 <item>When the <prgn>postrm</prgn> script is run with a
4914 first argument of <tt>remove</tt>, the script should call
4915 <prgn>ldconfig</prgn>.
4920 During install or upgrade, the preinst is called before
4921 the new files are installed, so calling "ldconfig" is
4922 pointless. The preinst of an existing package can also be
4923 called if an upgrade fails. However, this happens during
4924 the critical time when a shared libs may exist on-disk
4925 under a temporary name. Thus, it is dangerous and
4926 forbidden by current policy to call "ldconfig" at this
4931 When a package is installed or upgraded, "postinst
4932 configure" runs after the new files are safely on-disk.
4933 Since it is perfectly safe to invoke ldconfig
4934 unconditionally in a postinst, it is OK for a package to
4935 simply put ldconfig in its postinst without checking the
4936 argument. The postinst can also be called to recover from
4937 a failed upgrade. This happens before any new files are
4938 unpacked, so there is no reason to call "ldconfig" at this
4943 For a package that is being removed, prerm is
4944 called with all the files intact, so calling ldconfig is
4945 useless. The other calls to "prerm" happen in the case of
4946 upgrade at a time when all the files of the old package
4947 are on-disk, so again calling "ldconfig" is pointless.
4951 postrm, on the other hand, is called with the "remove"
4952 argument just after the files are removed, so this is
4953 the proper time to call "ldconfig" to notify the system
4954 of the fact that the shared libraries from the package
4955 are removed. The postrm can be called at several other
4956 times. At the time of "postrm purge", "postrm
4957 abort-install", or "postrm abort-upgrade", calling
4958 "ldconfig" is useless because the shared lib files are
4959 not on-disk. However, when "postrm" is invoked with
4960 arguments "upgrade", "failed-upgrade", or "disappear", a
4961 shared lib may exist on-disk under a temporary filename.
4969 <sect id="sharedlibs-support-files">
4970 <heading>Shared library support files</heading>
4973 If your package contains files whose names do not change with
4974 each change in the library shared object version, you must not
4975 put them in the shared library package. Otherwise, several
4976 versions of the shared library cannot be installed at the same
4977 time without filename clashes, making upgrades and transitions
4978 unnecessarily difficult.
4982 It is recommended that supporting files and run-time support
4983 programs that do not need to be invoked manually by users, but
4984 are nevertheless required for the package to function, be placed
4985 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
4986 preferably under <file>/usr/lib/</file><var>package-name</var>.
4987 If the program or file is architecture independent, the
4988 recommendation is for it to be placed in a subdirectory of
4989 <file>/usr/share</file> instead, preferably under
4990 <file>/usr/share/</file><var>package-name</var>. Following the
4991 <var>package-name</var> naming convention ensures that the file
4992 names change when the shared object version changes.
4996 Run-time support programs that use the shared library but are
4997 not required for the library to function or files used by the
4998 shared library that can be used by any version of the shared
4999 library package should instead be put in a separate package.
5000 This package might typically be named
5001 <package><var>libraryname</var>-tools</package>; note the
5002 absence of the <var>soversion</var> in the package name.
5006 Files and support programs only useful when compiling software
5007 against the library should be included in the development
5008 package for the library.<footnote>
5009 For example, a <file><var>package-name</var>-config</file>
5010 script or <package>pkg-config</package> configuration files.
5015 <sect id="sharedlibs-static">
5016 <heading>Static libraries</heading>
5019 The static library (<file><var>libraryname.a</var></file>)
5020 is usually provided in addition to the shared version.
5021 It is placed into the development package (see below).
5025 In some cases, it is acceptable for a library to be
5026 available in static form only; these cases include:
5028 <item>libraries for languages whose shared library support
5029 is immature or unstable</item>
5030 <item>libraries whose interfaces are in flux or under
5031 development (commonly the case when the library's
5032 major version number is zero, or where the ABI breaks
5033 across patchlevels)</item>
5034 <item>libraries which are explicitly intended to be
5035 available only in static form by their upstream
5040 <sect id="sharedlibs-dev">
5041 <heading>Development files</heading>
5044 The development files associated to a shared library need to be
5045 placed in a package called
5046 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5047 or if you prefer only to support one development version at a
5048 time, <package><var>libraryname</var>-dev</package>.
5052 In case several development versions of a library exist, you may
5053 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5054 <ref id="conflicts">) to ensure that the user only installs one
5055 development version at a time (as different development versions are
5056 likely to have the same header files in them, which would cause a
5057 filename clash if both were installed).
5061 The development package should contain a symlink for the associated
5062 shared library without a version number. For example, the
5063 <package>libgdbm-dev</package> package should include a symlink
5064 from <file>/usr/lib/libgdbm.so</file> to
5065 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5066 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5067 <file>libgdbm.so</file> when compiling dynamically.
5071 <sect id="sharedlibs-intradeps">
5072 <heading>Dependencies between the packages of the same library</heading>
5075 Typically the development version should have an exact
5076 version dependency on the runtime library, to make sure that
5077 compilation and linking happens correctly. The
5078 <tt>${binary:Version}</tt> substitution variable can be
5079 useful for this purpose.
5081 Previously, <tt>${Source-Version}</tt> was used, but its name
5082 was confusing and it has been deprecated since dpkg 1.13.19.
5087 <sect id="sharedlibs-shlibdeps">
5088 <heading>Dependencies between the library and other packages -
5089 the <tt>shlibs</tt> system</heading>
5092 If a package contains a binary or library which links to a
5093 shared library, we must ensure that when the package is
5094 installed on the system, all of the libraries needed are
5095 also installed. This requirement led to the creation of the
5096 <tt>shlibs</tt> system, which is very simple in its design:
5097 any package which <em>provides</em> a shared library also
5098 provides information on the package dependencies required to
5099 ensure the presence of this library, and any package which
5100 <em>uses</em> a shared library uses this information to
5101 determine the dependencies it requires. The files which
5102 contain the mapping from shared libraries to the necessary
5103 dependency information are called <file>shlibs</file> files.
5107 Thus, when a package is built which contains any shared
5108 libraries, it must provide a <file>shlibs</file> file for other
5109 packages to use, and when a package is built which contains
5110 any shared libraries or compiled binaries, it must run
5111 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5112 on these to determine the libraries used and hence the
5113 dependencies needed by this package.<footnote>
5115 In the past, the shared libraries linked to were
5116 determined by calling <prgn>ldd</prgn>, but now
5117 <prgn>objdump</prgn> is used to do this. The only
5118 change this makes to package building is that
5119 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5120 libraries, whereas in the past this was unnecessary.
5121 The rest of this footnote explains the advantage that
5126 We say that a binary <tt>foo</tt> <em>directly</em> uses
5127 a library <tt>libbar</tt> if it is explicitly linked
5128 with that library (that is, it uses the flag
5129 <tt>-lbar</tt> during the linking stage). Other
5130 libraries that are needed by <tt>libbar</tt> are linked
5131 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5132 linker will load them automatically when it loads
5133 <tt>libbar</tt>. A package should depend on
5134 the libraries it directly uses, and the dependencies for
5135 those libraries should automatically pull in the other
5140 Unfortunately, the <prgn>ldd</prgn> program shows both
5141 the directly and indirectly used libraries, meaning that
5142 the dependencies determined included both direct and
5143 indirect dependencies. The use of <prgn>objdump</prgn>
5144 avoids this problem by determining only the directly
5149 A good example of where this helps is the following. We
5150 could update <tt>libimlib</tt> with a new version that
5151 supports a new graphics format called dgf (but retaining
5152 the same major version number). If we used the old
5153 <prgn>ldd</prgn> method, every package that uses
5154 <tt>libimlib</tt> would need to be recompiled so it
5155 would also depend on <tt>libdgf</tt> or it wouldn't run
5156 due to missing symbols. However with the new system,
5157 packages using <tt>libimlib</tt> can rely on
5158 <tt>libimlib</tt> itself having the dependency on
5159 <tt>libdgf</tt> and so they would not need rebuilding.
5165 In the following sections, we will first describe where the
5166 various <tt>shlibs</tt> files are to be found, then how to
5167 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5168 file format and how to create them if your package contains a
5173 <heading>The <tt>shlibs</tt> files present on the system</heading>
5176 There are several places where <tt>shlibs</tt> files are
5177 found. The following list gives them in the order in which
5179 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5180 (The first one which gives the required information is used.)
5186 <p><file>debian/shlibs.local</file></p>
5189 This lists overrides for this package. Its use is
5190 described below (see <ref id="shlibslocal">).
5195 <p><file>/etc/dpkg/shlibs.override</file></p>
5198 This lists global overrides. This list is normally
5199 empty. It is maintained by the local system
5205 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5208 When packages are being built, any
5209 <file>debian/shlibs</file> files are copied into the
5210 control file area of the temporary build directory and
5211 given the name <file>shlibs</file>. These files give
5212 details of any shared libraries included in the
5214 An example may help here. Let us say that the
5215 source package <tt>foo</tt> generates two binary
5216 packages, <tt>libfoo2</tt> and
5217 <tt>foo-runtime</tt>. When building the binary
5218 packages, the two packages are created in the
5219 directories <file>debian/libfoo2</file> and
5220 <file>debian/foo-runtime</file> respectively.
5221 (<file>debian/tmp</file> could be used instead of one
5222 of these.) Since <tt>libfoo2</tt> provides the
5223 <tt>libfoo</tt> shared library, it will require a
5224 <tt>shlibs</tt> file, which will be installed in
5225 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5227 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5228 when <prgn>dpkg-shlibdeps</prgn> is run on the
5230 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5232 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5233 determine whether <tt>foo-prog</tt>'s library
5234 dependencies are satisfied by any of the libraries
5235 provided by <tt>libfoo2</tt>. For this reason,
5236 <prgn>dpkg-shlibdeps</prgn> must only be run once
5237 all of the individual binary packages'
5238 <tt>shlibs</tt> files have been installed into the
5245 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5248 These are the <file>shlibs</file> files corresponding to
5249 all of the packages installed on the system, and are
5250 maintained by the relevant package maintainers.
5255 <p><file>/etc/dpkg/shlibs.default</file></p>
5258 This file lists any shared libraries whose packages
5259 have failed to provide correct <file>shlibs</file> files.
5260 It was used when the <file>shlibs</file> setup was first
5261 introduced, but it is now normally empty. It is
5262 maintained by the <tt>dpkg</tt> maintainer.
5270 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5271 <file>shlibs</file> files</heading>
5275 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5276 into your <file>debian/rules</file> file. If your package
5277 contains only compiled binaries and libraries (but no scripts),
5278 you can use a command such as:
5279 <example compact="compact">
5280 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5281 debian/tmp/usr/lib/*
5283 Otherwise, you will need to explicitly list the compiled
5284 binaries and libraries.<footnote>
5285 If you are using <tt>debhelper</tt>, the
5286 <prgn>dh_shlibdeps</prgn> program will do this work for
5287 you. It will also correctly handle multi-binary
5293 This command puts the dependency information into the
5294 <file>debian/substvars</file> file, which is then used by
5295 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5296 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5297 field in the control file for this to work.
5301 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5302 done. If it does complain you might need to create your own
5303 <file>debian/shlibs.local</file> file, as explained below (see
5304 <ref id="shlibslocal">).
5308 If you have multiple binary packages, you will need to call
5309 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5310 compiled libraries or binaries. In such a case, you will
5311 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5312 utilities to specify a different <file>substvars</file> file.
5316 If you are creating a udeb for use in the Debian Installer, you
5317 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5318 the dependency line of type <tt>udeb</tt> by adding
5319 <tt>-tudeb</tt> as option<footnote>
5320 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5321 will automatically add this option if it knows it is
5323 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5324 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5325 fall back to the regular dependency line.
5329 For more details on dpkg-shlibdeps, please see
5330 <ref id="pkg-dpkg-shlibdeps"> and
5331 <manref name="dpkg-shlibdeps" section="1">.
5336 <heading>The <file>shlibs</file> File Format</heading>
5339 Each <file>shlibs</file> file has the same format. Lines
5340 beginning with <tt>#</tt> are considered to be comments and
5341 are ignored. Each line is of the form:
5342 <example compact="compact">
5343 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5348 We will explain this by reference to the example of the
5349 <tt>zlib1g</tt> package, which (at the time of writing)
5350 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5354 <var>type</var> is an optional element that indicates the type
5355 of package for which the line is valid. The only type currently
5356 in use is <tt>udeb</tt>. The colon and space after the type are
5361 <var>library-name</var> is the name of the shared library,
5362 in this case <tt>libz</tt>. (This must match the name part
5363 of the soname, see below.)
5367 <var>soname-version</var> is the version part of the soname of
5368 the library. The soname is the thing that must exactly match
5369 for the library to be recognized by the dynamic linker, and is
5371 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5372 example, <tt>libz.so.1</tt>.<footnote>
5373 This can be determined using the command
5374 <example compact="compact">
5375 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5378 The version part is the part which comes after
5379 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5383 <var>dependencies</var> has the same syntax as a dependency
5384 field in a binary package control file. It should give
5385 details of which packages are required to satisfy a binary
5386 built against the version of the library contained in the
5387 package. See <ref id="depsyntax"> for details.
5391 In our example, if the first version of the <tt>zlib1g</tt>
5392 package which contained a minor number of at least
5393 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5394 <tt>shlibs</tt> entry for this library could say:
5395 <example compact="compact">
5396 libz 1 zlib1g (>= 1:1.1.3)
5398 The version-specific dependency is to avoid warnings from
5399 the dynamic linker about using older shared libraries with
5404 As zlib1g also provides a udeb containing the shared library,
5405 there would also be a second line:
5406 <example compact="compact">
5407 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5413 <heading>Providing a <file>shlibs</file> file</heading>
5416 If your package provides a shared library, you need to create
5417 a <file>shlibs</file> file following the format described above.
5418 It is usual to call this file <file>debian/shlibs</file> (but if
5419 you have multiple binary packages, you might want to call it
5420 <file>debian/shlibs.<var>package</var></file> instead). Then
5421 let <file>debian/rules</file> install it in the control area:
5422 <example compact="compact">
5423 install -m644 debian/shlibs debian/tmp/DEBIAN
5425 or, in the case of a multi-binary package:
5426 <example compact="compact">
5427 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5429 An alternative way of doing this is to create the
5430 <file>shlibs</file> file in the control area directly from
5431 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5432 file at all,<footnote>
5433 This is what <prgn>dh_makeshlibs</prgn> in the
5434 <tt>debhelper</tt> suite does. If your package also has a udeb
5435 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5436 automatically generate the <tt>udeb:</tt> lines if you specify
5437 the name of the udeb with the <tt>--add-udeb</tt> option.
5439 since the <file>debian/shlibs</file> file itself is ignored by
5440 <prgn>dpkg-shlibdeps</prgn>.
5444 As <prgn>dpkg-shlibdeps</prgn> reads the
5445 <file>DEBIAN/shlibs</file> files in all of the binary packages
5446 being built from this source package, all of the
5447 <file>DEBIAN/shlibs</file> files should be installed before
5448 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5453 <sect1 id="shlibslocal">
5454 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5457 This file is intended only as a <em>temporary</em> fix if
5458 your binaries or libraries depend on a library whose package
5459 does not yet provide a correct <file>shlibs</file> file.
5463 We will assume that you are trying to package a binary
5464 <tt>foo</tt>. When you try running
5465 <prgn>dpkg-shlibdeps</prgn> you get the following error
5466 message (<tt>-O</tt> displays the dependency information on
5467 <tt>stdout</tt> instead of writing it to
5468 <tt>debian/substvars</tt>, and the lines have been wrapped
5469 for ease of reading):
5470 <example compact="compact">
5471 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5472 dpkg-shlibdeps: warning: unable to find dependency
5473 information for shared library libbar (soname 1,
5474 path /usr/lib/libbar.so.1, dependency field Depends)
5475 shlibs:Depends=libc6 (>= 2.2.2-2)
5477 You can then run <prgn>ldd</prgn> on the binary to find the
5478 full location of the library concerned:
5479 <example compact="compact">
5481 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5482 libc.so.6 => /lib/libc.so.6 (0x40032000)
5483 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5485 So the <prgn>foo</prgn> binary depends on the
5486 <prgn>libbar</prgn> shared library, but no package seems to
5487 provide a <file>*.shlibs</file> file handling
5488 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5489 determine the package responsible:
5490 <example compact="compact">
5491 $ dpkg -S /usr/lib/libbar.so.1
5492 bar1: /usr/lib/libbar.so.1
5493 $ dpkg -s bar1 | grep Version
5496 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5497 is the one we are using. Now we can file a bug against the
5498 <tt>bar1</tt> package and create our own
5499 <file>debian/shlibs.local</file> to locally fix the problem.
5500 Including the following line into your
5501 <file>debian/shlibs.local</file> file:
5502 <example compact="compact">
5503 libbar 1 bar1 (>= 1.0-1)
5505 should allow the package build to work.
5509 As soon as the maintainer of <tt>bar1</tt> provides a
5510 correct <file>shlibs</file> file, you should remove this line
5511 from your <file>debian/shlibs.local</file> file. (You should
5512 probably also then have a versioned <tt>Build-Depends</tt>
5513 on <tt>bar1</tt> to help ensure that others do not have the
5514 same problem building your package.)
5523 <chapt id="opersys"><heading>The Operating System</heading>
5526 <heading>File system hierarchy</heading>
5530 <heading>File System Structure</heading>
5533 The location of all installed files and directories must
5534 comply with the Filesystem Hierarchy Standard (FHS),
5535 version 2.3, with the exceptions noted below, and except
5536 where doing so would violate other terms of Debian
5537 Policy. The following exceptions to the FHS apply:
5542 The optional rules related to user specific
5543 configuration files for applications are stored in
5544 the user's home directory are relaxed. It is
5545 recommended that such files start with the
5546 '<tt>.</tt>' character (a "dot file"), and if an
5547 application needs to create more than one dot file
5548 then the preferred placement is in a subdirectory
5549 with a name starting with a '.' character, (a "dot
5550 directory"). In this case it is recommended the
5551 configuration files not start with the '.'
5557 The requirement for amd64 to use <file>/lib64</file>
5558 for 64 bit binaries is removed.
5563 The requirement that
5564 <file>/usr/local/share/man</file> be "synonymous"
5565 with <file>/usr/local/man</file> is relaxed to a
5570 The requirement that windowmanagers with a single
5571 configuration file call it <file>system.*wmrc</file>
5572 is removed, as is the restriction that the window
5573 manager subdirectory be named identically to the
5574 window manager name itself.
5579 The requirement that boot manager configuration
5580 files live in <file>/etc</file>, or at least are
5581 symlinked there, is relaxed to a recommendation.
5588 The version of this document referred here can be
5589 found in the <tt>debian-policy</tt> package or on <url
5590 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5591 name="FHS (Debian copy)"> alongside this manual (or, if
5592 you have the <package>debian-policy</package> installed,
5594 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5595 (local copy)">). The
5596 latest version, which may be a more recent version, may
5598 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5599 Specific questions about following the standard may be
5600 asked on the <tt>debian-devel</tt> mailing list, or
5601 referred to the FHS mailing list (see the
5602 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5608 <heading>Site-specific programs</heading>
5611 As mandated by the FHS, packages must not place any
5612 files in <file>/usr/local</file>, either by putting them in
5613 the file system archive to be unpacked by <prgn>dpkg</prgn>
5614 or by manipulating them in their maintainer scripts.
5618 However, the package may create empty directories below
5619 <file>/usr/local</file> so that the system administrator knows
5620 where to place site-specific files. These are not
5621 directories <em>in</em> <file>/usr/local</file>, but are
5622 children of directories in <file>/usr/local</file>. These
5623 directories (<file>/usr/local/*/dir/</file>)
5624 should be removed on package removal if they are
5629 Note, that this applies only to directories <em>below</em>
5630 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5631 Packages must not create sub-directories in the directory
5632 <file>/usr/local</file> itself, except those listed in FHS,
5633 section 4.5. However, you may create directories below
5634 them as you wish. You must not remove any of the
5635 directories listed in 4.5, even if you created them.
5639 Since <file>/usr/local</file> can be mounted read-only from a
5640 remote server, these directories must be created and
5641 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5642 maintainer scripts and not be included in the
5643 <file>.deb</file> archive. These scripts must not fail if
5644 either of these operations fail.
5648 For example, the <tt>emacsen-common</tt> package could
5649 contain something like
5650 <example compact="compact">
5651 if [ ! -e /usr/local/share/emacs ]
5653 if mkdir /usr/local/share/emacs 2>/dev/null
5655 chown root:staff /usr/local/share/emacs
5656 chmod 2775 /usr/local/share/emacs
5660 in its <prgn>postinst</prgn> script, and
5661 <example compact="compact">
5662 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5663 rmdir /usr/local/share/emacs 2>/dev/null || true
5665 in the <prgn>prerm</prgn> script. (Note that this form is
5666 used to ensure that if the script is interrupted, the
5667 directory <file>/usr/local/share/emacs</file> will still be
5672 If you do create a directory in <file>/usr/local</file> for
5673 local additions to a package, you should ensure that
5674 settings in <file>/usr/local</file> take precedence over the
5675 equivalents in <file>/usr</file>.
5679 However, because <file>/usr/local</file> and its contents are
5680 for exclusive use of the local administrator, a package
5681 must not rely on the presence or absence of files or
5682 directories in <file>/usr/local</file> for normal operation.
5686 The <file>/usr/local</file> directory itself and all the
5687 subdirectories created by the package should (by default) have
5688 permissions 2775 (group-writable and set-group-id) and be
5689 owned by <tt>root:staff</tt>.
5694 <heading>The system-wide mail directory</heading>
5696 The system-wide mail directory is <file>/var/mail</file>. This
5697 directory is part of the base system and should not owned
5698 by any particular mail agents. The use of the old
5699 location <file>/var/spool/mail</file> is deprecated, even
5700 though the spool may still be physically located there.
5706 <heading>Users and groups</heading>
5709 <heading>Introduction</heading>
5711 The Debian system can be configured to use either plain or
5716 Some user ids (UIDs) and group ids (GIDs) are reserved
5717 globally for use by certain packages. Because some
5718 packages need to include files which are owned by these
5719 users or groups, or need the ids compiled into binaries,
5720 these ids must be used on any Debian system only for the
5721 purpose for which they are allocated. This is a serious
5722 restriction, and we should avoid getting in the way of
5723 local administration policies. In particular, many sites
5724 allocate users and/or local system groups starting at 100.
5728 Apart from this we should have dynamically allocated ids,
5729 which should by default be arranged in some sensible
5730 order, but the behavior should be configurable.
5734 Packages other than <tt>base-passwd</tt> must not modify
5735 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5736 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5741 <heading>UID and GID classes</heading>
5743 The UID and GID numbers are divided into classes as
5749 Globally allocated by the Debian project, the same
5750 on every Debian system. These ids will appear in
5751 the <file>passwd</file> and <file>group</file> files of all
5752 Debian systems, new ids in this range being added
5753 automatically as the <tt>base-passwd</tt> package is
5758 Packages which need a single statically allocated
5759 uid or gid should use one of these; their
5760 maintainers should ask the <tt>base-passwd</tt>
5768 Dynamically allocated system users and groups.
5769 Packages which need a user or group, but can have
5770 this user or group allocated dynamically and
5771 differently on each system, should use <tt>adduser
5772 --system</tt> to create the group and/or user.
5773 <prgn>adduser</prgn> will check for the existence of
5774 the user or group, and if necessary choose an unused
5775 id based on the ranges specified in
5776 <file>adduser.conf</file>.
5780 <tag>1000-29999:</tag>
5783 Dynamically allocated user accounts. By default
5784 <prgn>adduser</prgn> will choose UIDs and GIDs for
5785 user accounts in this range, though
5786 <file>adduser.conf</file> may be used to modify this
5791 <tag>30000-59999:</tag>
5796 <tag>60000-64999:</tag>
5799 Globally allocated by the Debian project, but only
5800 created on demand. The ids are allocated centrally
5801 and statically, but the actual accounts are only
5802 created on users' systems on demand.
5806 These ids are for packages which are obscure or
5807 which require many statically-allocated ids. These
5808 packages should check for and create the accounts in
5809 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5810 <prgn>adduser</prgn> if it has this facility) if
5811 necessary. Packages which are likely to require
5812 further allocations should have a "hole" left after
5813 them in the allocation, to give them room to
5818 <tag>65000-65533:</tag>
5826 User <tt>nobody</tt>. The corresponding gid refers
5827 to the group <tt>nogroup</tt>.
5834 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5835 not</em> be used, because it is the error return
5844 <sect id="sysvinit">
5845 <heading>System run levels and <file>init.d</file> scripts</heading>
5847 <sect1 id="/etc/init.d">
5848 <heading>Introduction</heading>
5851 The <file>/etc/init.d</file> directory contains the scripts
5852 executed by <prgn>init</prgn> at boot time and when the
5853 init state (or "runlevel") is changed (see <manref
5854 name="init" section="8">).
5858 There are at least two different, yet functionally
5859 equivalent, ways of handling these scripts. For the sake
5860 of simplicity, this document describes only the symbolic
5861 link method. However, it must not be assumed by maintainer
5862 scripts that this method is being used, and any automated
5863 manipulation of the various runlevel behaviors by
5864 maintainer scripts must be performed using
5865 <prgn>update-rc.d</prgn> as described below and not by
5866 manually installing or removing symlinks. For information
5867 on the implementation details of the other method,
5868 implemented in the <tt>file-rc</tt> package, please refer
5869 to the documentation of that package.
5873 These scripts are referenced by symbolic links in the
5874 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5875 runlevels, <prgn>init</prgn> looks in the directory
5876 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5877 execute, where <tt><var>n</var></tt> is the runlevel that
5878 is being changed to, or <tt>S</tt> for the boot-up
5883 The names of the links all have the form
5884 <file>S<var>mm</var><var>script</var></file> or
5885 <file>K<var>mm</var><var>script</var></file> where
5886 <var>mm</var> is a two-digit number and <var>script</var>
5887 is the name of the script (this should be the same as the
5888 name of the actual script in <file>/etc/init.d</file>).
5892 When <prgn>init</prgn> changes runlevel first the targets
5893 of the links whose names start with a <tt>K</tt> are
5894 executed, each with the single argument <tt>stop</tt>,
5895 followed by the scripts prefixed with an <tt>S</tt>, each
5896 with the single argument <tt>start</tt>. (The links are
5897 those in the <file>/etc/rc<var>n</var>.d</file> directory
5898 corresponding to the new runlevel.) The <tt>K</tt> links
5899 are responsible for killing services and the <tt>S</tt>
5900 link for starting services upon entering the runlevel.
5904 For example, if we are changing from runlevel 2 to
5905 runlevel 3, init will first execute all of the <tt>K</tt>
5906 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5907 all of the <tt>S</tt> prefixed scripts in that directory.
5908 The links starting with <tt>K</tt> will cause the
5909 referred-to file to be executed with an argument of
5910 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5915 The two-digit number <var>mm</var> is used to determine
5916 the order in which to run the scripts: low-numbered links
5917 have their scripts run first. For example, the
5918 <tt>K20</tt> scripts will be executed before the
5919 <tt>K30</tt> scripts. This is used when a certain service
5920 must be started before another. For example, the name
5921 server <prgn>bind</prgn> might need to be started before
5922 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5923 can set up its access lists. In this case, the script
5924 that starts <prgn>bind</prgn> would have a lower number
5925 than the script that starts <prgn>inn</prgn> so that it
5927 <example compact="compact">
5934 The two runlevels 0 (halt) and 6 (reboot) are slightly
5935 different. In these runlevels, the links with an
5936 <tt>S</tt> prefix are still called after those with a
5937 <tt>K</tt> prefix, but they too are called with the single
5938 argument <tt>stop</tt>.
5943 <heading>Writing the scripts</heading>
5946 Packages that include daemons for system services should
5947 place scripts in <file>/etc/init.d</file> to start or stop
5948 services at boot time or during a change of runlevel.
5949 These scripts should be named
5950 <file>/etc/init.d/<var>package</var></file>, and they should
5951 accept one argument, saying what to do:
5954 <tag><tt>start</tt></tag>
5955 <item>start the service,</item>
5957 <tag><tt>stop</tt></tag>
5958 <item>stop the service,</item>
5960 <tag><tt>restart</tt></tag>
5961 <item>stop and restart the service if it's already running,
5962 otherwise start the service</item>
5964 <tag><tt>reload</tt></tag>
5965 <item><p>cause the configuration of the service to be
5966 reloaded without actually stopping and restarting
5969 <tag><tt>force-reload</tt></tag>
5970 <item>cause the configuration to be reloaded if the
5971 service supports this, otherwise restart the
5975 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5976 <tt>force-reload</tt> options should be supported by all
5977 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5982 The <file>init.d</file> scripts must ensure that they will
5983 behave sensibly (i.e., returning success and not starting
5984 multiple copies of a service) if invoked with <tt>start</tt>
5985 when the service is already running, or with <tt>stop</tt>
5986 when it isn't, and that they don't kill unfortunately-named
5987 user processes. The best way to achieve this is usually to
5988 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
5993 If a service reloads its configuration automatically (as
5994 in the case of <prgn>cron</prgn>, for example), the
5995 <tt>reload</tt> option of the <file>init.d</file> script
5996 should behave as if the configuration has been reloaded
6001 The <file>/etc/init.d</file> scripts must be treated as
6002 configuration files, either (if they are present in the
6003 package, that is, in the .deb file) by marking them as
6004 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6005 by managing them correctly in the maintainer scripts (see
6006 <ref id="config-files">). This is important since we want
6007 to give the local system administrator the chance to adapt
6008 the scripts to the local system, e.g., to disable a
6009 service without de-installing the package, or to specify
6010 some special command line options when starting a service,
6011 while making sure their changes aren't lost during the next
6016 These scripts should not fail obscurely when the
6017 configuration files remain but the package has been
6018 removed, as configuration files remain on the system after
6019 the package has been removed. Only when <prgn>dpkg</prgn>
6020 is executed with the <tt>--purge</tt> option will
6021 configuration files be removed. In particular, as the
6022 <file>/etc/init.d/<var>package</var></file> script itself is
6023 usually a <tt>conffile</tt>, it will remain on the system
6024 if the package is removed but not purged. Therefore, you
6025 should include a <tt>test</tt> statement at the top of the
6027 <example compact="compact">
6028 test -f <var>program-executed-later-in-script</var> || exit 0
6033 Often there are some variables in the <file>init.d</file>
6034 scripts whose values control the behavior of the scripts,
6035 and which a system administrator is likely to want to
6036 change. As the scripts themselves are frequently
6037 <tt>conffile</tt>s, modifying them requires that the
6038 administrator merge in their changes each time the package
6039 is upgraded and the <tt>conffile</tt> changes. To ease
6040 the burden on the system administrator, such configurable
6041 values should not be placed directly in the script.
6042 Instead, they should be placed in a file in
6043 <file>/etc/default</file>, which typically will have the same
6044 base name as the <file>init.d</file> script. This extra file
6045 should be sourced by the script when the script runs. It
6046 must contain only variable settings and comments in SUSv3
6047 <prgn>sh</prgn> format. It may either be a
6048 <tt>conffile</tt> or a configuration file maintained by
6049 the package maintainer scripts. See <ref id="config-files">
6054 To ensure that vital configurable values are always
6055 available, the <file>init.d</file> script should set default
6056 values for each of the shell variables it uses, either
6057 before sourcing the <file>/etc/default/</file> file or
6058 afterwards using something like the <tt>:
6059 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6060 script must behave sensibly and not fail if the
6061 <file>/etc/default</file> file is deleted.
6065 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6066 as temporary filesystems<footnote>
6067 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6068 options in <file>/etc/default/rcS</file>.
6069 </footnote>, so the <file>init.d</file> scripts must handle this
6070 correctly. This will typically amount to creating any required
6071 subdirectories dynamically when the <file>init.d</file> script
6072 is run, rather than including them in the package and relying on
6073 <prgn>dpkg</prgn> to create them.
6078 <heading>Interfacing with the initscript system</heading>
6081 Maintainers should use the abstraction layer provided by
6082 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6083 programs to deal with initscripts in their packages'
6084 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6085 and <prgn>postrm</prgn>.
6089 Directly managing the /etc/rc?.d links and directly
6090 invoking the <file>/etc/init.d/</file> initscripts should
6091 be done only by packages providing the initscript
6092 subsystem (such as <prgn>sysv-rc</prgn> and
6093 <prgn>file-rc</prgn>).
6097 <heading>Managing the links</heading>
6100 The program <prgn>update-rc.d</prgn> is provided for
6101 package maintainers to arrange for the proper creation and
6102 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6103 or their functional equivalent if another method is being
6104 used. This may be used by maintainers in their packages'
6105 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6109 You must not include any <file>/etc/rc<var>n</var>.d</file>
6110 symbolic links in the actual archive or manually create or
6111 remove the symbolic links in maintainer scripts; you must
6112 use the <prgn>update-rc.d</prgn> program instead. (The
6113 former will fail if an alternative method of maintaining
6114 runlevel information is being used.) You must not include
6115 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6116 in the archive either. (Only the <tt>sysvinit</tt>
6121 By default <prgn>update-rc.d</prgn> will start services in
6122 each of the multi-user state runlevels (2, 3, 4, and 5)
6123 and stop them in the halt runlevel (0), the single-user
6124 runlevel (1) and the reboot runlevel (6). The system
6125 administrator will have the opportunity to customize
6126 runlevels by simply adding, moving, or removing the
6127 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6128 symbolic links are being used, or by modifying
6129 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6134 To get the default behavior for your package, put in your
6135 <prgn>postinst</prgn> script
6136 <example compact="compact">
6137 update-rc.d <var>package</var> defaults
6139 and in your <prgn>postrm</prgn>
6140 <example compact="compact">
6141 if [ "$1" = purge ]; then
6142 update-rc.d <var>package</var> remove
6144 </example>. Note that if your package changes runlevels
6145 or priority, you may have to remove and recreate the links,
6146 since otherwise the old links may persist. Refer to the
6147 documentation of <prgn>update-rc.d</prgn>.
6151 This will use a default sequence number of 20. If it does
6152 not matter when or in which order the <file>init.d</file>
6153 script is run, use this default. If it does, then you
6154 should talk to the maintainer of the <prgn>sysvinit</prgn>
6155 package or post to <tt>debian-devel</tt>, and they will
6156 help you choose a number.
6160 For more information about using <tt>update-rc.d</tt>,
6161 please consult its man page <manref name="update-rc.d"
6167 <heading>Running initscripts</heading>
6169 The program <prgn>invoke-rc.d</prgn> is provided to make
6170 it easier for package maintainers to properly invoke an
6171 initscript, obeying runlevel and other locally-defined
6172 constraints that might limit a package's right to start,
6173 stop and otherwise manage services. This program may be
6174 used by maintainers in their packages' scripts.
6178 The package maintainer scripts must use
6179 <prgn>invoke-rc.d</prgn> to invoke the
6180 <file>/etc/init.d/*</file> initscripts, instead of
6181 calling them directly.
6185 By default, <prgn>invoke-rc.d</prgn> will pass any
6186 action requests (start, stop, reload, restart...) to the
6187 <file>/etc/init.d</file> script, filtering out requests
6188 to start or restart a service out of its intended
6193 Most packages will simply need to change:
6194 <example compact="compact">/etc/init.d/<package>
6195 <action></example> in their <prgn>postinst</prgn>
6196 and <prgn>prerm</prgn> scripts to:
6197 <example compact="compact">
6198 if which invoke-rc.d >/dev/null 2>&1; then
6199 invoke-rc.d <var>package</var> <action>
6201 /etc/init.d/<var>package</var> <action>
6207 A package should register its initscript services using
6208 <prgn>update-rc.d</prgn> before it tries to invoke them
6209 using <prgn>invoke-rc.d</prgn>. Invocation of
6210 unregistered services may fail.
6214 For more information about using
6215 <prgn>invoke-rc.d</prgn>, please consult its man page
6216 <manref name="invoke-rc.d" section="8">.
6222 <heading>Boot-time initialization</heading>
6225 There used to be another directory, <file>/etc/rc.boot</file>,
6226 which contained scripts which were run once per machine
6227 boot. This has been deprecated in favour of links from
6228 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6229 described in <ref id="/etc/init.d">. Packages must not
6230 place files in <file>/etc/rc.boot</file>.
6235 <heading>Example</heading>
6238 An example on which you can base your
6239 <file>/etc/init.d</file> scripts is found in
6240 <file>/etc/init.d/skeleton</file>.
6247 <heading>Console messages from <file>init.d</file> scripts</heading>
6250 This section describes the formats to be used for messages
6251 written to standard output by the <file>/etc/init.d</file>
6252 scripts. The intent is to improve the consistency of
6253 Debian's startup and shutdown look and feel. For this
6254 reason, please look very carefully at the details. We want
6255 the messages to have the same format in terms of wording,
6256 spaces, punctuation and case of letters.
6260 Here is a list of overall rules that should be used for
6261 messages generated by <file>/etc/init.d</file> scripts.
6267 The message should fit in one line (fewer than 80
6268 characters), start with a capital letter and end with
6269 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6273 If the script is performing some time consuming task in
6274 the background (not merely starting or stopping a
6275 program, for instance), an ellipsis (three dots:
6276 <tt>...</tt>) should be output to the screen, with no
6277 leading or tailing whitespace or line feeds.
6281 The messages should appear as if the computer is telling
6282 the user what it is doing (politely :-), but should not
6283 mention "it" directly. For example, instead of:
6284 <example compact="compact">
6285 I'm starting network daemons: nfsd mountd.
6287 the message should say
6288 <example compact="compact">
6289 Starting network daemons: nfsd mountd.
6296 <tt>init.d</tt> script should use the following standard
6297 message formats for the situations enumerated below.
6303 <p>When daemons are started</p>
6306 If the script starts one or more daemons, the output
6307 should look like this (a single line, no leading
6309 <example compact="compact">
6310 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6312 The <var>description</var> should describe the
6313 subsystem the daemon or set of daemons are part of,
6314 while <var>daemon-1</var> up to <var>daemon-n</var>
6315 denote each daemon's name (typically the file name of
6320 For example, the output of <file>/etc/init.d/lpd</file>
6322 <example compact="compact">
6323 Starting printer spooler: lpd.
6328 This can be achieved by saying
6329 <example compact="compact">
6330 echo -n "Starting printer spooler: lpd"
6331 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6334 in the script. If there are more than one daemon to
6335 start, the output should look like this:
6336 <example compact="compact">
6337 echo -n "Starting remote file system services:"
6338 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6339 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6340 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6343 This makes it possible for the user to see what is
6344 happening and when the final daemon has been started.
6345 Care should be taken in the placement of white spaces:
6346 in the example above the system administrators can
6347 easily comment out a line if they don't want to start
6348 a specific daemon, while the displayed message still
6354 <p>When a system parameter is being set</p>
6357 If you have to set up different system parameters
6358 during the system boot, you should use this format:
6359 <example compact="compact">
6360 Setting <var>parameter</var> to "<var>value</var>".
6365 You can use a statement such as the following to get
6367 <example compact="compact">
6368 echo "Setting DNS domainname to \"$domainname\"."
6373 Note that the same symbol (<tt>"</tt>) is used for the left
6374 and right quotation marks. A grave accent (<tt>`</tt>) is
6375 not a quote character; neither is an apostrophe
6381 <p>When a daemon is stopped or restarted</p>
6384 When you stop or restart a daemon, you should issue a
6385 message identical to the startup message, except that
6386 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6387 or <tt>Restarting</tt> respectively.
6391 For example, stopping the printer daemon will look like
6393 <example compact="compact">
6394 Stopping printer spooler: lpd.
6400 <p>When something is executed</p>
6403 There are several examples where you have to run a
6404 program at system startup or shutdown to perform a
6405 specific task, for example, setting the system's clock
6406 using <prgn>netdate</prgn> or killing all processes
6407 when the system shuts down. Your message should look
6409 <example compact="compact">
6410 Doing something very useful...done.
6412 You should print the <tt>done.</tt> immediately after
6413 the job has been completed, so that the user is
6414 informed why they have to wait. You can get this
6416 <example compact="compact">
6417 echo -n "Doing something very useful..."
6426 <p>When the configuration is reloaded</p>
6429 When a daemon is forced to reload its configuration
6430 files you should use the following format:
6431 <example compact="compact">
6432 Reloading <var>description</var> configuration...done.
6434 where <var>description</var> is the same as in the
6435 daemon starting message.
6443 <heading>Cron jobs</heading>
6446 Packages must not modify the configuration file
6447 <file>/etc/crontab</file>, and they must not modify the files in
6448 <file>/var/spool/cron/crontabs</file>.</p>
6451 If a package wants to install a job that has to be executed
6452 via cron, it should place a file with the name of the
6453 package in one or more of the following directories:
6454 <example compact="compact">
6460 As these directory names imply, the files within them are
6461 executed on an hourly, daily, weekly, or monthly basis,
6462 respectively. The exact times are listed in
6463 <file>/etc/crontab</file>.</p>
6466 All files installed in any of these directories must be
6467 scripts (e.g., shell scripts or Perl scripts) so that they
6468 can easily be modified by the local system administrator.
6469 In addition, they must be treated as configuration files.
6473 If a certain job has to be executed at some other frequency or
6474 at a specific time, the package should install a file
6475 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6476 same syntax as <file>/etc/crontab</file> and is processed by
6477 <prgn>cron</prgn> automatically. The file must also be
6478 treated as a configuration file. (Note that entries in the
6479 <file>/etc/cron.d</file> directory are not handled by
6480 <prgn>anacron</prgn>. Thus, you should only use this
6481 directory for jobs which may be skipped if the system is not
6485 The scripts or crontab entries in these directories should
6486 check if all necessary programs are installed before they
6487 try to execute them. Otherwise, problems will arise when a
6488 package was removed but not purged since configuration files
6489 are kept on the system in this situation.</p>
6493 <heading>Menus</heading>
6496 The Debian <tt>menu</tt> package provides a standard
6497 interface between packages providing applications and
6498 <em>menu programs</em> (either X window managers or
6499 text-based menu programs such as <prgn>pdmenu</prgn>).
6503 All packages that provide applications that need not be
6504 passed any special command line arguments for normal
6505 operation should register a menu entry for those
6506 applications, so that users of the <tt>menu</tt> package
6507 will automatically get menu entries in their window
6508 managers, as well in shells like <tt>pdmenu</tt>.
6512 Menu entries should follow the current menu policy.
6516 The menu policy can be found in the <tt>menu-policy</tt>
6517 files in the <tt>debian-policy</tt> package.
6518 It is also available from the Debian web mirrors at
6519 <tt><url name="/doc/packaging-manuals/menu-policy/"
6520 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6524 Please also refer to the <em>Debian Menu System</em>
6525 documentation that comes with the <package>menu</package>
6526 package for information about how to register your
6532 <heading>Multimedia handlers</heading>
6535 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6536 is a mechanism for encoding files and data streams and
6537 providing meta-information about them, in particular their
6538 type (e.g. audio or video) and format (e.g. PNG, HTML,
6543 Registration of MIME type handlers allows programs like mail
6544 user agents and web browsers to invoke these handlers to
6545 view, edit or display MIME types they don't support directly.
6549 Packages which provide the ability to view/show/play,
6550 compose, edit or print MIME types should register themselves
6551 as such following the current MIME support policy.
6555 The MIME support policy can be found in the <tt>mime-policy</tt>
6556 files in the <tt>debian-policy</tt> package.
6557 It is also available from the Debian web mirrors at
6558 <tt><url name="/doc/packaging-manuals/mime-policy/"
6559 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6565 <heading>Keyboard configuration</heading>
6568 To achieve a consistent keyboard configuration so that all
6569 applications interpret a keyboard event the same way, all
6570 programs in the Debian distribution must be configured to
6571 comply with the following guidelines.
6575 The following keys must have the specified interpretations:
6578 <tag><tt><--</tt></tag>
6579 <item>delete the character to the left of the cursor</item>
6581 <tag><tt>Delete</tt></tag>
6582 <item>delete the character to the right of the cursor</item>
6584 <tag><tt>Control+H</tt></tag>
6585 <item>emacs: the help prefix</item>
6588 The interpretation of any keyboard events should be
6589 independent of the terminal that is used, be it a virtual
6590 console, an X terminal emulator, an rlogin/telnet session,
6595 The following list explains how the different programs
6596 should be set up to achieve this:
6602 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6606 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6610 X translations are set up to make
6611 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6612 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6613 is the vt220 escape code for the "delete character"
6614 key). This must be done by loading the X resources
6615 using <prgn>xrdb</prgn> on all local X displays, not
6616 using the application defaults, so that the
6617 translation resources used correspond to the
6618 <prgn>xmodmap</prgn> settings.
6622 The Linux console is configured to make
6623 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6624 generate <tt>ESC [ 3 ~</tt>.
6628 X applications are configured so that <tt><</tt>
6629 deletes left, and <tt>Delete</tt> deletes right. Motif
6630 applications already work like this.
6634 Terminals should have <tt>stty erase ^?</tt> .
6638 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6639 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6640 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6644 Emacs is programmed to map <tt>KB_Backspace</tt> or
6645 the <tt>stty erase</tt> character to
6646 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6647 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6648 <tt>^H</tt> to <tt>help</tt> as always.
6652 Other applications use the <tt>stty erase</tt>
6653 character and <tt>kdch1</tt> for the two delete keys,
6654 with ASCII DEL being "delete previous character" and
6655 <tt>kdch1</tt> being "delete character under
6663 This will solve the problem except for the following
6670 Some terminals have a <tt><--</tt> key that cannot
6671 be made to produce anything except <tt>^H</tt>. On
6672 these terminals Emacs help will be unavailable on
6673 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6674 character takes precedence in Emacs, and has been set
6675 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6676 available) can be used instead.
6680 Some operating systems use <tt>^H</tt> for <tt>stty
6681 erase</tt>. However, modern telnet versions and all
6682 rlogin versions propagate <tt>stty</tt> settings, and
6683 almost all UNIX versions honour <tt>stty erase</tt>.
6684 Where the <tt>stty</tt> settings are not propagated
6685 correctly, things can be made to work by using
6686 <tt>stty</tt> manually.
6690 Some systems (including previous Debian versions) use
6691 <prgn>xmodmap</prgn> to arrange for both
6692 <tt><--</tt> and <tt>Delete</tt> to generate
6693 <tt>KB_Delete</tt>. We can change the behavior of
6694 their X clients using the same X resources that we use
6695 to do it for our own clients, or configure our clients
6696 using their resources when things are the other way
6697 around. On displays configured like this
6698 <tt>Delete</tt> will not work, but <tt><--</tt>
6703 Some operating systems have different <tt>kdch1</tt>
6704 settings in their <tt>terminfo</tt> database for
6705 <tt>xterm</tt> and others. On these systems the
6706 <tt>Delete</tt> key will not work correctly when you
6707 log in from a system conforming to our policy, but
6708 <tt><--</tt> will.
6715 <heading>Environment variables</heading>
6718 A program must not depend on environment variables to get
6719 reasonable defaults. (That's because these environment
6720 variables would have to be set in a system-wide
6721 configuration file like <file>/etc/profile</file>, which is not
6722 supported by all shells.)
6726 If a program usually depends on environment variables for its
6727 configuration, the program should be changed to fall back to
6728 a reasonable default configuration if these environment
6729 variables are not present. If this cannot be done easily
6730 (e.g., if the source code of a non-free program is not
6731 available), the program must be replaced by a small
6732 "wrapper" shell script which sets the environment variables
6733 if they are not already defined, and calls the original program.
6737 Here is an example of a wrapper script for this purpose:
6739 <example compact="compact">
6741 BAR=${BAR:-/var/lib/fubar}
6743 exec /usr/lib/foo/foo "$@"
6748 Furthermore, as <file>/etc/profile</file> is a configuration
6749 file of the <prgn>base-files</prgn> package, other packages must
6750 not put any environment variables or other commands into that
6755 <sect id="doc-base">
6756 <heading>Registering Documents using doc-base</heading>
6759 The <package>doc-base</package> package implements a
6760 flexible mechanism for handling and presenting
6761 documentation. The recommended practice is for every Debian
6762 package that provides online documentation (other than just
6763 manual pages) to register these documents with
6764 <package>doc-base</package> by installing a
6765 <package>doc-base</package> control file via the
6766 <prgn/install-docs/ script at installation time and
6767 de-register the manuals again when the package is removed.
6770 Please refer to the documentation that comes with the
6771 <package>doc-base</package> package for information and
6780 <heading>Files</heading>
6783 <heading>Binaries</heading>
6786 Two different packages must not install programs with
6787 different functionality but with the same filenames. (The
6788 case of two programs having the same functionality but
6789 different implementations is handled via "alternatives" or
6790 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6791 <ref id="conflicts"> respectively.) If this case happens,
6792 one of the programs must be renamed. The maintainers should
6793 report this to the <tt>debian-devel</tt> mailing list and
6794 try to find a consensus about which program will have to be
6795 renamed. If a consensus cannot be reached, <em>both</em>
6796 programs must be renamed.
6800 By default, when a package is being built, any binaries
6801 created should include debugging information, as well as
6802 being compiled with optimization. You should also turn on
6803 as many reasonable compilation warnings as possible; this
6804 makes life easier for porters, who can then look at build
6805 logs for possible problems. For the C programming language,
6806 this means the following compilation parameters should be
6808 <example compact="compact">
6810 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6812 INSTALL = install -s # (or use strip on the files in debian/tmp)
6817 Note that by default all installed binaries should be stripped,
6818 either by using the <tt>-s</tt> flag to
6819 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6820 the binaries after they have been copied into
6821 <file>debian/tmp</file> but before the tree is made into a
6826 Although binaries in the build tree should be compiled with
6827 debugging information by default, it can often be difficult to
6828 debug programs if they are also subjected to compiler
6829 optimization. For this reason, it is recommended to support the
6830 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6831 (see <ref id="debianrules-options">). This variable can contain
6832 several flags to change how a package is compiled and built.
6836 It is up to the package maintainer to decide what
6837 compilation options are best for the package. Certain
6838 binaries (such as computationally-intensive programs) will
6839 function better with certain flags (<tt>-O3</tt>, for
6840 example); feel free to use them. Please use good judgment
6841 here. Don't use flags for the sake of it; only use them
6842 if there is good reason to do so. Feel free to override
6843 the upstream author's ideas about which compilation
6844 options are best: they are often inappropriate for our
6850 <sect id="libraries">
6851 <heading>Libraries</heading>
6854 If the package is <strong>architecture: any</strong>, then
6855 the shared library compilation and linking flags must have
6856 <tt>-fPIC</tt>, or the package shall not build on some of
6857 the supported architectures<footnote>
6859 If you are using GCC, <tt>-fPIC</tt> produces code with
6860 relocatable position independent code, which is required for
6861 most architectures to create a shared library, with i386 and
6862 perhaps some others where non position independent code is
6863 permitted in a shared library.
6866 Position independent code may have a performance penalty,
6867 especially on <tt>i386</tt>. However, in most cases the
6868 speed penalty must be measured against the memory wasted on
6869 the few architectures where non position independent code is
6872 </footnote>. Any exception to this rule must be discussed on
6873 the mailing list <em>debian-devel@lists.debian.org</em>, and
6874 a rough consensus obtained. The reasons for not compiling
6875 with <tt>-fPIC</tt> flag must be recorded in the file
6876 <tt>README.Debian</tt>, and care must be taken to either
6877 restrict the architecture or arrange for <tt>-fPIC</tt> to
6878 be used on architectures where it is required.<footnote>
6880 Some of the reasons why this might be required is if the
6881 library contains hand crafted assembly code that is not
6882 relocatable, the speed penalty is excessive for compute
6883 intensive libs, and similar reasons.
6888 As to the static libraries, the common case is not to have
6889 relocatable code, since there is no benefit, unless in specific
6890 cases; therefore the static version must not be compiled
6891 with the <tt>-fPIC</tt> flag. Any exception to this rule
6892 should be discussed on the mailing list
6893 <em>debian-devel@lists.debian.org</em>, and the reasons for
6894 compiling with the <tt>-fPIC</tt> flag must be recorded in
6895 the file <tt>README.Debian</tt>. <footnote>
6897 Some of the reasons for linking static libraries with
6898 the <tt>-fPIC</tt> flag are if, for example, one needs a
6899 Perl API for a library that is under rapid development,
6900 and has an unstable API, so shared libraries are
6901 pointless at this phase of the library's development. In
6902 that case, since Perl needs a library with relocatable
6903 code, it may make sense to create a static library with
6904 relocatable code. Another reason cited is if you are
6905 distilling various libraries into a common shared
6906 library, like <tt>mklibs</tt> does in the Debian
6912 In other words, if both a shared and a static library is
6913 being built, each source unit (<tt>*.c</tt>, for example,
6914 for C files) will need to be compiled twice, for the normal
6918 You must specify the gcc option <tt>-D_REENTRANT</tt>
6919 when building a library (either static or shared) to make
6920 the library compatible with LinuxThreads.
6924 Although not enforced by the build tools, shared libraries
6925 must be linked against all libraries that they use symbols from
6926 in the same way that binaries are. This ensures the correct
6927 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6928 system and guarantees that all libraries can be safely opened
6929 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6930 option <tt>-Wl,-z,defs</tt> when building a shared library.
6931 Since this option enforces symbol resolution at build time,
6932 a missing library reference will be caught early as a fatal
6937 All installed shared libraries should be stripped with
6938 <example compact="compact">
6939 strip --strip-unneeded <var>your-lib</var>
6941 (The option <tt>--strip-unneeded</tt> makes
6942 <prgn>strip</prgn> remove only the symbols which aren't
6943 needed for relocation processing.) Shared libraries can
6944 function perfectly well when stripped, since the symbols for
6945 dynamic linking are in a separate part of the ELF object
6947 You might also want to use the options
6948 <tt>--remove-section=.comment</tt> and
6949 <tt>--remove-section=.note</tt> on both shared libraries
6950 and executables, and <tt>--strip-debug</tt> on static
6956 Note that under some circumstances it may be useful to
6957 install a shared library unstripped, for example when
6958 building a separate package to support debugging.
6962 Shared object files (often <file>.so</file> files) that are not
6963 public libraries, that is, they are not meant to be linked
6964 to by third party executables (binaries of other packages),
6965 should be installed in subdirectories of the
6966 <file>/usr/lib</file> directory. Such files are exempt from the
6967 rules that govern ordinary shared libraries, except that
6968 they must not be installed executable and should be
6970 A common example are the so-called "plug-ins",
6971 internal shared objects that are dynamically loaded by
6972 programs using <manref name="dlopen" section="3">.
6977 Packages containing shared libraries that may be linked to
6978 by other packages' binaries, but which for some
6979 <em>compelling</em> reason can not be installed in
6980 <file>/usr/lib</file> directory, may install the shared library
6981 files in subdirectories of the <file>/usr/lib</file> directory,
6982 in which case they should arrange to add that directory in
6983 <file>/etc/ld.so.conf</file> in the package's post-installation
6984 script, and remove it in the package's post-removal script.
6988 An ever increasing number of packages are using
6989 <prgn>libtool</prgn> to do their linking. The latest GNU
6990 libtools (>= 1.3a) can take advantage of the metadata in the
6991 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6992 files). The main advantage of <prgn>libtool</prgn>'s
6993 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6994 store and subsequently access metadata with respect to the
6995 libraries it builds. <prgn>libtool</prgn> will search for
6996 those files, which contain a lot of useful information about
6997 a library (such as library dependency information for static
6998 linking). Also, they're <em>essential</em> for programs
6999 using <tt>libltdl</tt>.<footnote>
7000 Although <prgn>libtool</prgn> is fully capable of
7001 linking against shared libraries which don't have
7002 <tt>.la</tt> files, as it is a mere shell script it can
7003 add considerably to the build time of a
7004 <prgn>libtool</prgn>-using package if that shell script
7005 has to derive all this information from first principles
7006 for each library every time it is linked. With the
7007 advent of <prgn>libtool</prgn> version 1.4 (and to a
7008 lesser extent <prgn>libtool</prgn> version 1.3), the
7009 <file>.la</file> files also store information about
7010 inter-library dependencies which cannot necessarily be
7011 derived after the <file>.la</file> file is deleted.
7016 Packages that use <prgn>libtool</prgn> to create shared
7017 libraries should include the <file>.la</file> files in the
7018 <tt>-dev</tt> package, unless the package relies on
7019 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7020 the <tt>.la</tt> files must go in the run-time library
7025 You must make sure that you use only released versions of
7026 shared libraries to build your packages; otherwise other
7027 users will not be able to run your binaries
7028 properly. Producing source packages that depend on
7029 unreleased compilers is also usually a bad
7036 <heading>Shared libraries</heading>
7038 This section has moved to <ref id="sharedlibs">.
7044 <heading>Scripts</heading>
7047 All command scripts, including the package maintainer
7048 scripts inside the package and used by <prgn>dpkg</prgn>,
7049 should have a <tt>#!</tt> line naming the shell to be used
7054 In the case of Perl scripts this should be
7055 <tt>#!/usr/bin/perl</tt>.
7059 When scripts are installed into a directory in the system
7060 PATH, the script name should not include an extension such
7061 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7062 language currently used to implement it.
7065 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7066 should almost certainly start with <tt>set -e</tt> so that
7067 errors are detected. Every script should use
7068 <tt>set -e</tt> or check the exit status of <em>every</em>
7073 Scripts may assume that <file>/bin/sh</file> implements the
7074 SUSv3 Shell Command Language<footnote>
7075 Single UNIX Specification, version 3, which is also IEEE
7076 1003.1-2004 (POSIX), and is available on the World Wide Web
7077 from <url id="http://www.unix.org/version3/online.html"
7078 name="The Open Group"> after free
7079 registration.</footnote>
7080 plus the following additional features not mandated by
7082 These features are in widespread use in the Linux community
7083 and are implemented in all of bash, dash, and ksh, the most
7084 common shells users may wish to use as <file>/bin/sh</file>.
7087 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7088 must not generate a newline.</item>
7089 <item><tt>test</tt>, if implemented as a shell built-in, must
7090 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7092 <item><tt>local</tt> to create a scoped variable must be
7093 supported, including listing multiple variables in a single
7094 local command and assigning a value to a variable at the
7095 same time as localizing it. <tt>local</tt> may or
7096 may not preserve the variable value from an outer scope if
7097 no assignment is present. Uses such as:
7101 # ... use a, b, c, d ...
7104 must be supported and must set the value of <tt>c</tt> to
7108 If a shell script requires non-SUSv3 features from the shell
7109 interpreter other than those listed above, the appropriate shell
7110 must be specified in the first line of the script (e.g.,
7111 <tt>#!/bin/bash</tt>) and the package must depend on the package
7112 providing the shell (unless the shell package is marked
7113 "Essential", as in the case of <prgn>bash</prgn>).
7117 You may wish to restrict your script to SUSv3 features plus the
7118 above set when possible so that it may use <file>/bin/sh</file>
7119 as its interpreter. If your script works with <prgn>dash</prgn>
7120 (originally called <prgn>ash</prgn>), it probably complies with
7121 the above requirements, but if you are in doubt, use
7122 <file>/bin/bash</file>.
7126 Perl scripts should check for errors when making any
7127 system calls, including <tt>open</tt>, <tt>print</tt>,
7128 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7132 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7133 scripting languages. See <em>Csh Programming Considered
7134 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7135 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7136 If an upstream package comes with <prgn>csh</prgn> scripts
7137 then you must make sure that they start with
7138 <tt>#!/bin/csh</tt> and make your package depend on the
7139 <prgn>c-shell</prgn> virtual package.
7143 Any scripts which create files in world-writeable
7144 directories (e.g., in <file>/tmp</file>) must use a
7145 mechanism which will fail atomically if a file with the same
7146 name already exists.
7150 The Debian base system provides the <prgn>tempfile</prgn>
7151 and <prgn>mktemp</prgn> utilities for use by scripts for
7158 <heading>Symbolic links</heading>
7161 In general, symbolic links within a top-level directory
7162 should be relative, and symbolic links pointing from one
7163 top-level directory into another should be absolute. (A
7164 top-level directory is a sub-directory of the root
7165 directory <file>/</file>.)
7169 In addition, symbolic links should be specified as short as
7170 possible, i.e., link targets like <file>foo/../bar</file> are
7175 Note that when creating a relative link using
7176 <prgn>ln</prgn> it is not necessary for the target of the
7177 link to exist relative to the working directory you're
7178 running <prgn>ln</prgn> from, nor is it necessary to change
7179 directory to the directory where the link is to be made.
7180 Simply include the string that should appear as the target
7181 of the link (this will be a pathname relative to the
7182 directory in which the link resides) as the first argument
7187 For example, in your <prgn>Makefile</prgn> or
7188 <file>debian/rules</file>, you can do things like:
7189 <example compact="compact">
7190 ln -fs gcc $(prefix)/bin/cc
7191 ln -fs gcc debian/tmp/usr/bin/cc
7192 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7193 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7198 A symbolic link pointing to a compressed file should always
7199 have the same file extension as the referenced file. (For
7200 example, if a file <file>foo.gz</file> is referenced by a
7201 symbolic link, the filename of the link has to end with
7202 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7207 <heading>Device files</heading>
7210 Packages must not include device files in the package file
7215 If a package needs any special device files that are not
7216 included in the base system, it must call
7217 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7218 after notifying the user<footnote>
7219 This notification could be done via a (low-priority)
7220 debconf message, or an echo (printf) statement.
7225 Packages must not remove any device files in the
7226 <prgn>postrm</prgn> or any other script. This is left to the
7227 system administrator.
7231 Debian uses the serial devices
7232 <file>/dev/ttyS*</file>. Programs using the old
7233 <file>/dev/cu*</file> devices should be changed to use
7234 <file>/dev/ttyS*</file>.
7238 <sect id="config-files">
7239 <heading>Configuration files</heading>
7242 <heading>Definitions</heading>
7246 <tag>configuration file</tag>
7248 A file that affects the operation of a program, or
7249 provides site- or host-specific information, or
7250 otherwise customizes the behavior of a program.
7251 Typically, configuration files are intended to be
7252 modified by the system administrator (if needed or
7253 desired) to conform to local policy or to provide
7254 more useful site-specific behavior.
7257 <tag><tt>conffile</tt></tag>
7259 A file listed in a package's <tt>conffiles</tt>
7260 file, and is treated specially by <prgn>dpkg</prgn>
7261 (see <ref id="configdetails">).
7267 The distinction between these two is important; they are
7268 not interchangeable concepts. Almost all
7269 <tt>conffile</tt>s are configuration files, but many
7270 configuration files are not <tt>conffiles</tt>.
7274 As noted elsewhere, <file>/etc/init.d</file> scripts,
7275 <file>/etc/default</file> files, scripts installed in
7276 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7277 configuration installed in <file>/etc/cron.d</file> must be
7278 treated as configuration files. In general, any script that
7279 embeds configuration information is de-facto a configuration
7280 file and should be treated as such.
7285 <heading>Location</heading>
7288 Any configuration files created or used by your package
7289 must reside in <file>/etc</file>. If there are several,
7290 consider creating a subdirectory of <file>/etc</file>
7291 named after your package.
7295 If your package creates or uses configuration files
7296 outside of <file>/etc</file>, and it is not feasible to modify
7297 the package to use <file>/etc</file> directly, put the files
7298 in <file>/etc</file> and create symbolic links to those files
7299 from the location that the package requires.
7304 <heading>Behavior</heading>
7307 Configuration file handling must conform to the following
7309 <list compact="compact">
7311 local changes must be preserved during a package
7315 configuration files must be preserved when the
7316 package is removed, and only deleted when the
7323 The easy way to achieve this behavior is to make the
7324 configuration file a <tt>conffile</tt>. This is
7325 appropriate only if it is possible to distribute a default
7326 version that will work for most installations, although
7327 some system administrators may choose to modify it. This
7328 implies that the default version will be part of the
7329 package distribution, and must not be modified by the
7330 maintainer scripts during installation (or at any other
7335 In order to ensure that local changes are preserved
7336 correctly, no package may contain or make hard links to
7337 conffiles.<footnote>
7338 Rationale: There are two problems with hard links.
7339 The first is that some editors break the link while
7340 editing one of the files, so that the two files may
7341 unwittingly become unlinked and different. The second
7342 is that <prgn>dpkg</prgn> might break the hard link
7343 while upgrading <tt>conffile</tt>s.
7348 The other way to do it is via the maintainer scripts. In
7349 this case, the configuration file must not be listed as a
7350 <tt>conffile</tt> and must not be part of the package
7351 distribution. If the existence of a file is required for
7352 the package to be sensibly configured it is the
7353 responsibility of the package maintainer to provide
7354 maintainer scripts which correctly create, update and
7355 maintain the file and remove it on purge. (See <ref
7356 id="maintainerscripts"> for more information.) These
7357 scripts must be idempotent (i.e., must work correctly if
7358 <prgn>dpkg</prgn> needs to re-run them due to errors
7359 during installation or removal), must cope with all the
7360 variety of ways <prgn>dpkg</prgn> can call maintainer
7361 scripts, must not overwrite or otherwise mangle the user's
7362 configuration without asking, must not ask unnecessary
7363 questions (particularly during upgrades), and must
7364 otherwise be good citizens.
7368 The scripts are not required to configure every possible
7369 option for the package, but only those necessary to get
7370 the package running on a given system. Ideally the
7371 sysadmin should not have to do any configuration other
7372 than that done (semi-)automatically by the
7373 <prgn>postinst</prgn> script.
7377 A common practice is to create a script called
7378 <file><var>package</var>-configure</file> and have the
7379 package's <prgn>postinst</prgn> call it if and only if the
7380 configuration file does not already exist. In certain
7381 cases it is useful for there to be an example or template
7382 file which the maintainer scripts use. Such files should
7383 be in <file>/usr/share/<var>package</var></file> or
7384 <file>/usr/lib/<var>package</var></file> (depending on whether
7385 they are architecture-independent or not). There should
7386 be symbolic links to them from
7387 <file>/usr/share/doc/<var>package</var>/examples</file> if
7388 they are examples, and should be perfectly ordinary
7389 <prgn>dpkg</prgn>-handled files (<em>not</em>
7390 configuration files).
7394 These two styles of configuration file handling must
7395 not be mixed, for that way lies madness:
7396 <prgn>dpkg</prgn> will ask about overwriting the file
7397 every time the package is upgraded.
7402 <heading>Sharing configuration files</heading>
7405 Packages which specify the same file as a
7406 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7407 with each other. (This is an instance of the general rule
7408 about not sharing files. Note that neither alternatives
7409 nor diversions are likely to be appropriate in this case;
7410 in particular, <prgn>dpkg</prgn> does not handle diverted
7411 <tt>conffile</tt>s well.)
7415 The maintainer scripts must not alter a <tt>conffile</tt>
7416 of <em>any</em> package, including the one the scripts
7421 If two or more packages use the same configuration file
7422 and it is reasonable for both to be installed at the same
7423 time, one of these packages must be defined as
7424 <em>owner</em> of the configuration file, i.e., it will be
7425 the package which handles that file as a configuration
7426 file. Other packages that use the configuration file must
7427 depend on the owning package if they require the
7428 configuration file to operate. If the other package will
7429 use the configuration file if present, but is capable of
7430 operating without it, no dependency need be declared.
7434 If it is desirable for two or more related packages to
7435 share a configuration file <em>and</em> for all of the
7436 related packages to be able to modify that configuration
7437 file, then the following should be done:
7438 <enumlist compact="compact">
7440 One of the related packages (the "owning" package)
7441 will manage the configuration file with maintainer
7442 scripts as described in the previous section.
7445 The owning package should also provide a program
7446 that the other packages may use to modify the
7450 The related packages must use the provided program
7451 to make any desired modifications to the
7452 configuration file. They should either depend on
7453 the core package to guarantee that the configuration
7454 modifier program is available or accept gracefully
7455 that they cannot modify the configuration file if it
7456 is not. (This is in addition to the fact that the
7457 configuration file may not even be present in the
7464 Sometimes it's appropriate to create a new package which
7465 provides the basic infrastructure for the other packages
7466 and which manages the shared configuration files. (The
7467 <tt>sgml-base</tt> package is a good example.)
7472 <heading>User configuration files ("dotfiles")</heading>
7475 The files in <file>/etc/skel</file> will automatically be
7476 copied into new user accounts by <prgn>adduser</prgn>.
7477 No other program should reference the files in
7478 <file>/etc/skel</file>.
7482 Therefore, if a program needs a dotfile to exist in
7483 advance in <file>$HOME</file> to work sensibly, that dotfile
7484 should be installed in <file>/etc/skel</file> and treated as a
7489 However, programs that require dotfiles in order to
7490 operate sensibly are a bad thing, unless they do create
7491 the dotfiles themselves automatically.
7495 Furthermore, programs should be configured by the Debian
7496 default installation to behave as closely to the upstream
7497 default behavior as possible.
7501 Therefore, if a program in a Debian package needs to be
7502 configured in some way in order to operate sensibly, that
7503 should be done using a site-wide configuration file placed
7504 in <file>/etc</file>. Only if the program doesn't support a
7505 site-wide default configuration and the package maintainer
7506 doesn't have time to add it may a default per-user file be
7507 placed in <file>/etc/skel</file>.
7511 <file>/etc/skel</file> should be as empty as we can make it.
7512 This is particularly true because there is no easy (or
7513 necessarily desirable) mechanism for ensuring that the
7514 appropriate dotfiles are copied into the accounts of
7515 existing users when a package is installed.
7521 <heading>Log files</heading>
7523 Log files should usually be named
7524 <file>/var/log/<var>package</var>.log</file>. If you have many
7525 log files, or need a separate directory for permission
7526 reasons (<file>/var/log</file> is writable only by
7527 <file>root</file>), you should usually create a directory named
7528 <file>/var/log/<var>package</var></file> and place your log
7533 Log files must be rotated occasionally so that they don't
7534 grow indefinitely; the best way to do this is to drop a log
7535 rotation configuration file into the directory
7536 <file>/etc/logrotate.d</file> and use the facilities provided by
7537 logrotate.<footnote>
7539 The traditional approach to log files has been to set up
7540 <em>ad hoc</em> log rotation schemes using simple shell
7541 scripts and cron. While this approach is highly
7542 customizable, it requires quite a lot of sysadmin work.
7543 Even though the original Debian system helped a little
7544 by automatically installing a system which can be used
7545 as a template, this was deemed not enough.
7549 The use of <prgn>logrotate</prgn>, a program developed
7550 by Red Hat, is better, as it centralizes log management.
7551 It has both a configuration file
7552 (<file>/etc/logrotate.conf</file>) and a directory where
7553 packages can drop their individual log rotation
7554 configurations (<file>/etc/logrotate.d</file>).
7557 Here is a good example for a logrotate config
7558 file (for more information see <manref name="logrotate"
7560 <example compact="compact">
7561 /var/log/foo/*.log {
7566 /etc/init.d/foo force-reload
7570 This rotates all files under <file>/var/log/foo</file>, saves 12
7571 compressed generations, and forces the daemon to reload its
7572 configuration information after the log rotation.
7576 Log files should be removed when the package is
7577 purged (but not when it is only removed). This should be
7578 done by the <prgn>postrm</prgn> script when it is called
7579 with the argument <tt>purge</tt> (see <ref
7580 id="removedetails">).
7585 <heading>Permissions and owners</heading>
7588 The rules in this section are guidelines for general use.
7589 If necessary you may deviate from the details below.
7590 However, if you do so you must make sure that what is done
7591 is secure and you should try to be as consistent as possible
7592 with the rest of the system. You should probably also
7593 discuss it on <prgn>debian-devel</prgn> first.
7597 Files should be owned by <tt>root:root</tt>, and made
7598 writable only by the owner and universally readable (and
7599 executable, if appropriate), that is mode 644 or 755.
7603 Directories should be mode 755 or (for group-writability)
7604 mode 2775. The ownership of the directory should be
7605 consistent with its mode: if a directory is mode 2775, it
7606 should be owned by the group that needs write access to
7609 When a package is upgraded, and the owner or permissions
7610 of a file included in the package has changed, dpkg
7611 arranges for the ownership and permissions to be
7612 correctly set upon installation. However, this does not
7613 extend to directories; the permissions and ownership of
7614 directories already on the system does not change on
7615 install or upgrade of packages. This makes sense, since
7616 otherwise common directories like <tt>/usr</tt> would
7617 always be in flux. To correctly change permissions of a
7618 directory the package owns, explicit action is required,
7619 usually in the <tt>postinst</tt> script. Care must be
7620 taken to handle downgrades as well, in that case.
7627 Setuid and setgid executables should be mode 4755 or 2755
7628 respectively, and owned by the appropriate user or group.
7629 They should not be made unreadable (modes like 4711 or
7630 2711 or even 4111); doing so achieves no extra security,
7631 because anyone can find the binary in the freely available
7632 Debian package; it is merely inconvenient. For the same
7633 reason you should not restrict read or execute permissions
7634 on non-set-id executables.
7638 Some setuid programs need to be restricted to particular
7639 sets of users, using file permissions. In this case they
7640 should be owned by the uid to which they are set-id, and by
7641 the group which should be allowed to execute them. They
7642 should have mode 4754; again there is no point in making
7643 them unreadable to those users who must not be allowed to
7648 It is possible to arrange that the system administrator can
7649 reconfigure the package to correspond to their local
7650 security policy by changing the permissions on a binary:
7651 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7652 described below.<footnote>
7653 Ordinary files installed by <prgn>dpkg</prgn> (as
7654 opposed to <tt>conffile</tt>s and other similar objects)
7655 normally have their permissions reset to the distributed
7656 permissions when the package is reinstalled. However,
7657 the use of <prgn>dpkg-statoverride</prgn> overrides this
7658 default behavior. If you use this method, you should
7659 remember to describe <prgn>dpkg-statoverride</prgn> in
7660 the package documentation; being a relatively new
7661 addition to Debian, it is probably not yet well-known.
7663 Another method you should consider is to create a group for
7664 people allowed to use the program(s) and make any setuid
7665 executables executable only by that group.
7669 If you need to create a new user or group for your package
7670 there are two possibilities. Firstly, you may need to
7671 make some files in the binary package be owned by this
7672 user or group, or you may need to compile the user or
7673 group id (rather than just the name) into the binary
7674 (though this latter should be avoided if possible, as in
7675 this case you need a statically allocated id).</p>
7678 If you need a statically allocated id, you must ask for a
7679 user or group id from the <tt>base-passwd</tt> maintainer,
7680 and must not release the package until you have been
7681 allocated one. Once you have been allocated one you must
7682 either make the package depend on a version of the
7683 <tt>base-passwd</tt> package with the id present in
7684 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7685 your package to create the user or group itself with the
7686 correct id (using <tt>adduser</tt>) in its
7687 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7688 the <prgn>postinst</prgn> is to be preferred if it is
7689 possible, otherwise a pre-dependency will be needed on the
7690 <tt>adduser</tt> package.)
7694 On the other hand, the program might be able to determine
7695 the uid or gid from the user or group name at runtime, so
7696 that a dynamically allocated id can be used. In this case
7697 you should choose an appropriate user or group name,
7698 discussing this on <prgn>debian-devel</prgn> and checking
7699 with the <package/base-passwd/ maintainer that it is unique and that
7700 they do not wish you to use a statically allocated id
7701 instead. When this has been checked you must arrange for
7702 your package to create the user or group if necessary using
7703 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7704 <prgn>postinst</prgn> script (again, the latter is to be
7705 preferred if it is possible).
7709 Note that changing the numeric value of an id associated
7710 with a name is very difficult, and involves searching the
7711 file system for all appropriate files. You need to think
7712 carefully whether a static or dynamic id is required, since
7713 changing your mind later will cause problems.
7716 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7718 This section is not intended as policy, but as a
7719 description of the use of <prgn>dpkg-statoverride</prgn>.
7723 If a system administrator wishes to have a file (or
7724 directory or other such thing) installed with owner and
7725 permissions different from those in the distributed Debian
7726 package, they can use the <prgn>dpkg-statoverride</prgn>
7727 program to instruct <prgn>dpkg</prgn> to use the different
7728 settings every time the file is installed. Thus the
7729 package maintainer should distribute the files with their
7730 normal permissions, and leave it for the system
7731 administrator to make any desired changes. For example, a
7732 daemon which is normally required to be setuid root, but
7733 in certain situations could be used without being setuid,
7734 should be installed setuid in the <tt>.deb</tt>. Then the
7735 local system administrator can change this if they wish.
7736 If there are two standard ways of doing it, the package
7737 maintainer can use <tt>debconf</tt> to find out the
7738 preference, and call <prgn>dpkg-statoverride</prgn> in the
7739 maintainer script if necessary to accommodate the system
7740 administrator's choice. Care must be taken during
7741 upgrades to not override an existing setting.
7745 Given the above, <prgn>dpkg-statoverride</prgn> is
7746 essentially a tool for system administrators and would not
7747 normally be needed in the maintainer scripts. There is
7748 one type of situation, though, where calls to
7749 <prgn>dpkg-statoverride</prgn> would be needed in the
7750 maintainer scripts, and that involves packages which use
7751 dynamically allocated user or group ids. In such a
7752 situation, something like the following idiom can be very
7753 helpful in the package's <prgn>postinst</prgn>, where
7754 <tt>sysuser</tt> is a dynamically allocated id:
7756 for i in /usr/bin/foo /usr/sbin/bar
7758 # only do something when no setting exists
7759 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7761 #include: debconf processing, question about foo and bar
7762 if [ "$RET" = "true" ] ; then
7763 dpkg-statoverride --update --add sysuser root 4755 $i
7768 The corresponding <tt>dpkg-statoverride --remove</tt>
7769 calls can then be made unconditionally when the package is
7777 <chapt id="customized-programs">
7778 <heading>Customized programs</heading>
7780 <sect id="arch-spec">
7781 <heading>Architecture specification strings</heading>
7784 If a program needs to specify an <em>architecture specification
7785 string</em> in some place, it should select one of the
7786 strings provided by <tt>dpkg-architecture -L</tt>. The
7787 strings are in the format
7788 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7789 is sometimes elided, as when the OS is Linux.<footnote>
7790 <p>Currently, the strings are:
7791 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7792 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7793 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7794 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7795 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7796 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7797 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7798 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7799 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7800 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7801 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7802 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7803 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7804 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7805 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7806 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7807 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7808 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7809 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7810 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7811 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7812 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7813 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7814 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7815 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7816 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7817 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7818 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7819 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7820 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7821 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7822 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7823 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7824 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7825 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7826 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7827 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7833 Note that we don't want to use
7834 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7835 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7836 since this would make our programs incompatible with other
7837 Linux distributions. We also don't use something like
7838 <tt><var>arch</var>-unknown-linux</tt>, since the
7839 <tt>unknown</tt> does not look very good.
7844 <heading>Daemons</heading>
7847 The configuration files <file>/etc/services</file>,
7848 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7849 by the <prgn>netbase</prgn> package and must not be modified
7854 If a package requires a new entry in one of these files, the
7855 maintainer should get in contact with the
7856 <prgn>netbase</prgn> maintainer, who will add the entries
7857 and release a new version of the <prgn>netbase</prgn>
7862 The configuration file <file>/etc/inetd.conf</file> must not be
7863 modified by the package's scripts except via the
7864 <prgn>update-inetd</prgn> script or the
7865 <file>DebianNet.pm</file> Perl module. See their documentation
7866 for details on how to add entries.
7870 If a package wants to install an example entry into
7871 <file>/etc/inetd.conf</file>, the entry must be preceded with
7872 exactly one hash character (<tt>#</tt>). Such lines are
7873 treated as "commented out by user" by the
7874 <prgn>update-inetd</prgn> script and are not changed or
7875 activated during package updates.
7880 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7884 Some programs need to create pseudo-ttys. This should be done
7885 using Unix98 ptys if the C library supports it. The resulting
7886 program must not be installed setuid root, unless that
7887 is required for other functionality.
7891 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7892 <file>/var/log/lastlog</file> must be installed writable by
7893 group <tt>utmp</tt>. Programs which need to modify those
7894 files must be installed setgid <tt>utmp</tt>.
7899 <heading>Editors and pagers</heading>
7902 Some programs have the ability to launch an editor or pager
7903 program to edit or display a text document. Since there are
7904 lots of different editors and pagers available in the Debian
7905 distribution, the system administrator and each user should
7906 have the possibility to choose their preferred editor and
7911 In addition, every program should choose a good default
7912 editor/pager if none is selected by the user or system
7917 Thus, every program that launches an editor or pager must
7918 use the EDITOR or PAGER environment variable to determine
7919 the editor or pager the user wishes to use. If these
7920 variables are not set, the programs <file>/usr/bin/editor</file>
7921 and <file>/usr/bin/pager</file> should be used, respectively.
7925 These two files are managed through the <prgn>dpkg</prgn>
7926 "alternatives" mechanism. Thus every package providing an
7927 editor or pager must call the
7928 <prgn>update-alternatives</prgn> script to register these
7933 If it is very hard to adapt a program to make use of the
7934 EDITOR or PAGER variables, that program may be configured to
7935 use <file>/usr/bin/sensible-editor</file> and
7936 <file>/usr/bin/sensible-pager</file> as the editor or pager
7937 program respectively. These are two scripts provided in the
7938 Debian base system that check the EDITOR and PAGER variables
7939 and launch the appropriate program, and fall back to
7940 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7941 variable is not set.
7945 A program may also use the VISUAL environment variable to
7946 determine the user's choice of editor. If it exists, it
7947 should take precedence over EDITOR. This is in fact what
7948 <file>/usr/bin/sensible-editor</file> does.
7952 It is not required for a package to depend on
7953 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7954 package to provide such virtual packages.<footnote>
7955 The Debian base system already provides an editor and a
7961 <sect id="web-appl">
7962 <heading>Web servers and applications</heading>
7965 This section describes the locations and URLs that should
7966 be used by all web servers and web applications in the
7973 Cgi-bin executable files are installed in the
7975 <example compact="compact">
7976 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7978 and should be referred to as
7979 <example compact="compact">
7980 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7986 <p>Access to HTML documents</p>
7989 HTML documents for a package are stored in
7990 <file>/usr/share/doc/<var>package</var></file>
7991 and can be referred to as
7992 <example compact="compact">
7993 http://localhost/doc/<var>package</var>/<var>filename</var>
7998 The web server should restrict access to the document
7999 tree so that only clients on the same host can read
8000 the documents. If the web server does not support such
8001 access controls, then it should not provide access at
8002 all, or ask about providing access during installation.
8007 <p>Access to images</p>
8009 It is recommended that images for a package be stored
8010 in <tt>/usr/share/images/<var>package</var></tt> and
8011 may be referred to through an alias <tt>/images/</tt>
8014 http://localhost/images/<package>/<filename>
8021 <p>Web Document Root</p>
8024 Web Applications should try to avoid storing files in
8025 the Web Document Root. Instead they should use the
8026 /usr/share/doc/<var>package</var> directory for
8027 documents and register the Web Application via the
8028 <package>doc-base</package> package. If access to the
8029 web document root is unavoidable then use
8030 <example compact="compact">
8033 as the Document Root. This might be just a symbolic
8034 link to the location where the system administrator
8035 has put the real document root.
8038 <item><p>Providing httpd and/or httpd-cgi</p>
8040 All web servers should provide the virtual package
8041 <tt>httpd</tt>. If a web server has CGI support it should
8042 provide <tt>httpd-cgi</tt> additionally.
8045 All web applications which do not contain CGI scripts should
8046 depend on <tt>httpd</tt>, all those web applications which
8047 <tt>do</tt> contain CGI scripts, should depend on
8055 <sect id="mail-transport-agents">
8056 <heading>Mail transport, delivery and user agents</heading>
8059 Debian packages which process electronic mail, whether mail
8060 user agents (MUAs) or mail transport agents (MTAs), must
8061 ensure that they are compatible with the configuration
8062 decisions below. Failure to do this may result in lost
8063 mail, broken <tt>From:</tt> lines, and other serious brain
8068 The mail spool is <file>/var/mail</file> and the interface to
8069 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8070 the FHS). On older systems, the mail spool may be
8071 physically located in <file>/var/spool/mail</file>, but all
8072 access to the mail spool should be via the
8073 <file>/var/mail</file> symlink. The mail spool is part of the
8074 base system and not part of the MTA package.
8078 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8079 programs (such as IMAP daemons) must lock the mailbox in an
8080 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8081 be combined with dot locking. To avoid deadlocks, a program
8082 should use <tt>fcntl()</tt> first and dot locking after
8083 this, or alternatively implement the two locking methods in
8084 a non blocking way<footnote>
8085 If it is not possible to establish both locks, the
8086 system shouldn't wait for the second lock to be
8087 established, but remove the first lock, wait a (random)
8088 time, and start over locking again.
8089 </footnote>. Using the functions <tt>maillock</tt> and
8090 <tt>mailunlock</tt> provided by the
8091 <tt>liblockfile*</tt><footnote>
8092 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8093 to use these functions.
8094 </footnote> packages is the recommended way to realize this.
8098 Mailboxes are generally either mode 600 and owned by
8099 <var>user</var> or mode 660 and owned by
8100 <tt><var>user</var>:mail</tt><footnote>
8101 There are two traditional permission schemes for mail spools:
8102 mode 600 with all mail delivery done by processes running as
8103 the destination user, or mode 660 and owned by group mail with
8104 mail delivery done by a process running as a system user in
8105 group mail. Historically, Debian required mode 660 mail
8106 spools to enable the latter model, but that model has become
8107 increasingly uncommon and the principle of least privilege
8108 indicates that mail systems that use the first model should
8109 use permissions of 600. If delivery to programs is permitted,
8110 it's easier to keep the mail system secure if the delivery
8111 agent runs as the destination user. Debian Policy therefore
8112 permits either scheme.
8113 </footnote>. The local system administrator may choose a
8114 different permission scheme; packages should not make
8115 assumptions about the permission and ownership of mailboxes
8116 unless required (such as when creating a new mailbox). A MUA
8117 may remove a mailbox (unless it has nonstandard permissions) in
8118 which case the MTA or another MUA must recreate it if needed.
8122 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8123 be setgid mail to do the locking mentioned above (and
8124 must obviously avoid accessing other users' mailboxes
8125 using this privilege).</p>
8128 <file>/etc/aliases</file> is the source file for the system mail
8129 aliases (e.g., postmaster, usenet, etc.), it is the one
8130 which the sysadmin and <prgn>postinst</prgn> scripts may
8131 edit. After <file>/etc/aliases</file> is edited the program or
8132 human editing it must call <prgn>newaliases</prgn>. All MTA
8133 packages must come with a <prgn>newaliases</prgn> program,
8134 even if it does nothing, but older MTA packages did not do
8135 this so programs should not fail if <prgn>newaliases</prgn>
8136 cannot be found. Note that because of this, all MTA
8137 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8138 <tt>Replaces: mail-transport-agent</tt> control file
8143 The convention of writing <tt>forward to
8144 <var>address</var></tt> in the mailbox itself is not
8145 supported. Use a <tt>.forward</tt> file instead.</p>
8148 The <prgn>rmail</prgn> program used by UUCP
8149 for incoming mail should be <file>/usr/sbin/rmail</file>.
8150 Likewise, <prgn>rsmtp</prgn>, for receiving
8151 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8155 If your package needs to know what hostname to use on (for
8156 example) outgoing news and mail messages which are generated
8157 locally, you should use the file <file>/etc/mailname</file>. It
8158 will contain the portion after the username and <tt>@</tt>
8159 (at) sign for email addresses of users on the machine
8160 (followed by a newline).
8164 Such a package should check for the existence of this file
8165 when it is being configured. If it exists, it should be
8166 used without comment, although an MTA's configuration script
8167 may wish to prompt the user even if it finds that this file
8168 exists. If the file does not exist, the package should
8169 prompt the user for the value (preferably using
8170 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8171 as well as using it in the package's configuration. The
8172 prompt should make it clear that the name will not just be
8173 used by that package. For example, in this situation the
8174 <tt>inn</tt> package could say something like:
8175 <example compact="compact">
8176 Please enter the "mail name" of your system. This is the
8177 hostname portion of the address to be shown on outgoing
8178 news and mail messages. The default is
8179 <var>syshostname</var>, your system's host name. Mail
8180 name ["<var>syshostname</var>"]:
8182 where <var>syshostname</var> is the output of <tt>hostname
8188 <heading>News system configuration</heading>
8191 All the configuration files related to the NNTP (news)
8192 servers and clients should be located under
8193 <file>/etc/news</file>.</p>
8196 There are some configuration issues that apply to a number
8197 of news clients and server packages on the machine. These
8201 <tag><file>/etc/news/organization</file></tag>
8203 A string which should appear as the
8204 organization header for all messages posted
8205 by NNTP clients on the machine
8208 <tag><file>/etc/news/server</file></tag>
8210 Contains the FQDN of the upstream NNTP
8211 server, or localhost if the local machine is
8216 Other global files may be added as required for cross-package news
8223 <heading>Programs for the X Window System</heading>
8226 <heading>Providing X support and package priorities</heading>
8229 Programs that can be configured with support for the X
8230 Window System must be configured to do so and must declare
8231 any package dependencies necessary to satisfy their
8232 runtime requirements when using the X Window System. If
8233 such a package is of higher priority than the X packages
8234 on which it depends, it is required that either the
8235 X-specific components be split into a separate package, or
8236 that an alternative version of the package, which includes
8237 X support, be provided, or that the package's priority be
8243 <heading>Packages providing an X server</heading>
8246 Packages that provide an X server that, directly or
8247 indirectly, communicates with real input and display
8248 hardware should declare in their control data that they
8249 provide the virtual package <tt>xserver</tt>.<footnote>
8250 This implements current practice, and provides an
8251 actual policy for usage of the <tt>xserver</tt>
8252 virtual package which appears in the virtual packages
8253 list. In a nutshell, X servers that interface
8254 directly with the display and input hardware or via
8255 another subsystem (e.g., GGI) should provide
8256 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8257 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8263 <heading>Packages providing a terminal emulator</heading>
8266 Packages that provide a terminal emulator for the X Window
8267 System which meet the criteria listed below should declare
8268 in their control data that they provide the virtual
8269 package <tt>x-terminal-emulator</tt>. They should also
8270 register themselves as an alternative for
8271 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8276 To be an <tt>x-terminal-emulator</tt>, a program must:
8277 <list compact="compact">
8279 Be able to emulate a DEC VT100 terminal, or a
8280 compatible terminal.
8284 Support the command-line option <tt>-e
8285 <var>command</var></tt>, which creates a new
8286 terminal window<footnote>
8287 "New terminal window" does not necessarily mean
8288 a new top-level X window directly parented by
8289 the window manager; it could, if the terminal
8290 emulator application were so coded, be a new
8291 "view" in a multiple-document interface (MDI).
8293 and runs the specified <var>command</var>,
8294 interpreting the entirety of the rest of the command
8295 line as a command to pass straight to exec, in the
8296 manner that <tt>xterm</tt> does.
8300 Support the command-line option <tt>-T
8301 <var>title</var></tt>, which creates a new terminal
8302 window with the window title <var>title</var>.
8309 <heading>Packages providing a window manager</heading>
8312 Packages that provide a window manager should declare in
8313 their control data that they provide the virtual package
8314 <tt>x-window-manager</tt>. They should also register
8315 themselves as an alternative for
8316 <file>/usr/bin/x-window-manager</file>, with a priority
8317 calculated as follows:
8318 <list compact="compact">
8320 Start with a priority of 20.
8324 If the window manager supports the Debian menu
8325 system, add 20 points if this support is available
8326 in the package's default configuration (i.e., no
8327 configuration files belonging to the system or user
8328 have to be edited to activate the feature); if
8329 configuration files must be modified, add only 10
8335 If the window manager complies with <url
8336 id="http://www.freedesktop.org/Standards/wm-spec"
8337 name="The Window Manager Specification Project">,
8338 written by the <url id="http://www.freedesktop.org/"
8339 name="Free Desktop Group">, add 40 points.
8343 If the window manager permits the X session to be
8344 restarted using a <em>different</em> window manager
8345 (without killing the X server) in its default
8346 configuration, add 10 points; otherwise add none.
8353 <heading>Packages providing fonts</heading>
8356 Packages that provide fonts for the X Window
8358 For the purposes of Debian Policy, a "font for the X
8359 Window System" is one which is accessed via X protocol
8360 requests. Fonts for the Linux console, for PostScript
8361 renderer, or any other purpose, do not fit this
8362 definition. Any tool which makes such fonts available
8363 to the X Window System, however, must abide by this
8366 must do a number of things to ensure that they are both
8367 available without modification of the X or font server
8368 configuration, and that they do not corrupt files used by
8369 other font packages to register information about
8373 Fonts of any type supported by the X Window System
8374 must be in a separate binary package from any
8375 executables, libraries, or documentation (except
8376 that specific to the fonts shipped, such as their
8377 license information). If one or more of the fonts
8378 so packaged are necessary for proper operation of
8379 the package with which they are associated the font
8380 package may be Recommended; if the fonts merely
8381 provide an enhancement, a Suggests relationship may
8382 be used. Packages must not Depend on font
8384 This is because the X server may retrieve fonts
8385 from the local file system or over the network
8386 from an X font server; the Debian package system
8387 is empowered to deal only with the local
8393 BDF fonts must be converted to PCF fonts with the
8394 <prgn>bdftopcf</prgn> utility (available in the
8395 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8396 placed in a directory that corresponds to their
8398 <list compact="compact">
8400 100 dpi fonts must be placed in
8401 <file>/usr/share/fonts/X11/100dpi/</file>.
8405 75 dpi fonts must be placed in
8406 <file>/usr/share/fonts/X11/75dpi/</file>.
8410 Character-cell fonts, cursor fonts, and other
8411 low-resolution fonts must be placed in
8412 <file>/usr/share/fonts/X11/misc/</file>.
8418 Type 1 fonts must be placed in
8419 <file>/usr/share/fonts/X11/Type1/</file>. If font
8420 metric files are available, they must be placed here
8425 Subdirectories of <file>/usr/share/fonts/X11/</file>
8426 other than those listed above must be neither
8427 created nor used. (The <file>PEX</file>, <file>CID</file>,
8428 <file>Speedo</file>, and <file>cyrillic</file> directories
8429 are excepted for historical reasons, but installation of
8430 files into these directories remains discouraged.)
8434 Font packages may, instead of placing files directly
8435 in the X font directories listed above, provide
8436 symbolic links in that font directory pointing to
8437 the files' actual location in the filesystem. Such
8438 a location must comply with the FHS.
8442 Font packages should not contain both 75dpi and
8443 100dpi versions of a font. If both are available,
8444 they should be provided in separate binary packages
8445 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8446 the names of the packages containing the
8447 corresponding fonts.
8451 Fonts destined for the <file>misc</file> subdirectory
8452 should not be included in the same package as 75dpi
8453 or 100dpi fonts; instead, they should be provided in
8454 a separate package with <tt>-misc</tt> appended to
8459 Font packages must not provide the files
8460 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8461 <file>fonts.scale</file> in a font directory:
8464 <file>fonts.dir</file> files must not be provided at all.
8468 <file>fonts.alias</file> and <file>fonts.scale</file>
8469 files, if needed, should be provided in the
8471 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8472 where <var>fontdir</var> is the name of the
8474 <file>/usr/share/fonts/X11/</file> where the
8475 package's corresponding fonts are stored
8476 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8477 <var>package</var> is the name of the package
8478 that provides these fonts, and
8479 <var>extension</var> is either <tt>scale</tt>
8480 or <tt>alias</tt>, whichever corresponds to
8487 Font packages must declare a dependency on
8488 <tt>xfonts-utils</tt> in their control
8493 Font packages that provide one or more
8494 <file>fonts.scale</file> files as described above must
8495 invoke <prgn>update-fonts-scale</prgn> on each
8496 directory into which they installed fonts
8497 <em>before</em> invoking
8498 <prgn>update-fonts-dir</prgn> on that directory.
8499 This invocation must occur in both the
8500 <prgn>postinst</prgn> (for all arguments) and
8501 <prgn>postrm</prgn> (for all arguments except
8502 <tt>upgrade</tt>) scripts.
8506 Font packages that provide one or more
8507 <file>fonts.alias</file> files as described above must
8508 invoke <prgn>update-fonts-alias</prgn> on each
8509 directory into which they installed fonts. This
8510 invocation must occur in both the
8511 <prgn>postinst</prgn> (for all arguments) and
8512 <prgn>postrm</prgn> (for all arguments except
8513 <tt>upgrade</tt>) scripts.
8517 Font packages must invoke
8518 <prgn>update-fonts-dir</prgn> on each directory into
8519 which they installed fonts. This invocation must
8520 occur in both the <prgn>postinst</prgn> (for all
8521 arguments) and <prgn>postrm</prgn> (for all
8522 arguments except <tt>upgrade</tt>) scripts.
8526 Font packages must not provide alias names for the
8527 fonts they include which collide with alias names
8528 already in use by fonts already packaged.
8532 Font packages must not provide fonts with the same
8533 XLFD registry name as another font already packaged.
8540 <heading>Application defaults files</heading>
8543 Application defaults files must be installed in the
8544 directory <file>/etc/X11/app-defaults/</file> (use of a
8545 localized subdirectory of <file>/etc/X11/</file> as described
8546 in the <em>X Toolkit Intrinsics - C Language
8547 Interface</em> manual is also permitted). They must be
8548 registered as <tt>conffile</tt>s or handled as
8549 configuration files.
8553 Customization of programs' X resources may also be
8554 supported with the provision of a file with the same name
8555 as that of the package placed in the
8556 <file>/etc/X11/Xresources/</file> directory, which must
8557 registered as a <tt>conffile</tt> or handled as a
8558 configuration file.<footnote>
8559 Note that this mechanism is not the same as using
8560 app-defaults; app-defaults are tied to the client
8561 binary on the local file system, whereas X resources
8562 are stored in the X server and affect all connecting
8569 <heading>Installation directory issues</heading>
8572 Packages using the X Window System should not be
8573 configured to install files under the
8574 <file>/usr/X11R6/</file> directory. The
8575 <file>/usr/X11R6/</file> directory hierarchy should be
8576 regarded as obsolete.
8580 Programs that use GNU <prgn>autoconf</prgn> and
8581 <prgn>automake</prgn> are usually easily configured at
8582 compile time to use <file>/usr/</file> instead of
8583 <file>/usr/X11R6/</file>, and this should be done whenever
8584 possible. Configuration files for window managers and
8585 display managers should be placed in a subdirectory of
8586 <file>/etc/X11/</file> corresponding to the package name due
8587 to these programs' tight integration with the mechanisms
8588 of the X Window System. Application-level programs should
8589 use the <file>/etc/</file> directory unless otherwise mandated
8594 The installation of files into subdirectories
8595 of <file>/usr/X11R6/include/X11/</file> and
8596 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8597 package maintainers should determine if subdirectories of
8598 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8603 Packages should install any relevant files into the
8604 directories <file>/usr/include/X11/</file> and
8605 <file>/usr/lib/X11/</file>, but if they do so, they must
8606 pre-depend on <tt>x11-common (>=
8607 1:7.0.0)</tt><footnote>
8609 These libraries used to be all symbolic
8610 links. However, with <tt>X11R7</tt>,
8611 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8612 are now real directories, and packages
8613 <strong>should</strong> ship their files here instead
8614 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8615 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8616 responsible for converting these symlinks into
8624 <heading>The OSF/Motif and OpenMotif libraries</heading>
8627 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8628 OpenMotif libraries</em><footnote>
8629 OSF/Motif and OpenMotif are collectively referred to as
8630 "Motif" in this policy document.
8632 should be compiled against and tested with LessTif (a free
8633 re-implementation of Motif) instead. If the maintainer
8634 judges that the program or programs do not work
8635 sufficiently well with LessTif to be distributed and
8636 supported, but do so when compiled against Motif, then two
8637 versions of the package should be created; one linked
8638 statically against Motif and with <tt>-smotif</tt>
8639 appended to the package name, and one linked dynamically
8640 against Motif and with <tt>-dmotif</tt> appended to the
8645 Both Motif-linked versions are dependent
8646 upon non-DFSG-compliant software and thus cannot be
8647 uploaded to the <em>main</em> distribution; if the
8648 software is itself DFSG-compliant it may be uploaded to
8649 the <em>contrib</em> distribution. While known existing
8650 versions of Motif permit unlimited redistribution of
8651 binaries linked against the library (whether statically or
8652 dynamically), it is the package maintainer's
8653 responsibility to determine whether this is permitted by
8654 the license of the copy of Motif in their possession.
8660 <heading>Perl programs and modules</heading>
8663 Perl programs and modules should follow the current Perl policy.
8667 The Perl policy can be found in the <tt>perl-policy</tt>
8668 files in the <tt>debian-policy</tt> package.
8669 It is also available from the Debian web mirrors at
8670 <tt><url name="/doc/packaging-manuals/perl-policy/"
8671 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8676 <heading>Emacs lisp programs</heading>
8679 Please refer to the "Debian Emacs Policy" for details of how to
8680 package emacs lisp programs.
8684 The Emacs policy is available in
8685 <file>debian-emacs-policy.gz</file> of the
8686 <package>emacsen-common</package> package.
8687 It is also available from the Debian web mirrors at
8688 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8689 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8694 <heading>Games</heading>
8697 The permissions on <file>/var/games</file> are mode 755, owner
8698 <tt>root</tt> and group <tt>root</tt>.
8702 Each game decides on its own security policy.</p>
8705 Games which require protected, privileged access to
8706 high-score files, saved games, etc., may be made
8707 set-<em>group</em>-id (mode 2755) and owned by
8708 <tt>root:games</tt>, and use files and directories with
8709 appropriate permissions (770 <tt>root:games</tt>, for
8710 example). They must not be made
8711 set-<em>user</em>-id, as this causes security problems. (If
8712 an attacker can subvert any set-user-id game they can
8713 overwrite the executable of any other, causing other players
8714 of these games to run a Trojan horse program. With a
8715 set-group-id game the attacker only gets access to less
8716 important game data, and if they can get at the other
8717 players' accounts at all it will take considerably more
8721 Some packages, for example some fortune cookie programs, are
8722 configured by the upstream authors to install with their
8723 data files or other static information made unreadable so
8724 that they can only be accessed through set-id programs
8725 provided. You should not do this in a Debian package: anyone can
8726 download the <file>.deb</file> file and read the data from it,
8727 so there is no point making the files unreadable. Not
8728 making the files unreadable also means that you don't have
8729 to make so many programs set-id, which reduces the risk of a
8733 As described in the FHS, binaries of games should be
8734 installed in the directory <file>/usr/games</file>. This also
8735 applies to games that use the X Window System. Manual pages
8736 for games (X and non-X games) should be installed in
8737 <file>/usr/share/man/man6</file>.</p>
8743 <heading>Documentation</heading>
8746 <heading>Manual pages</heading>
8749 You should install manual pages in <prgn>nroff</prgn> source
8750 form, in appropriate places under <file>/usr/share/man</file>.
8751 You should only use sections 1 to 9 (see the FHS for more
8752 details). You must not install a pre-formatted "cat page".
8756 Each program, utility, and function should have an
8757 associated manual page included in the same package. It is
8758 suggested that all configuration files also have a manual
8759 page included as well. Manual pages for protocols and other
8760 auxiliary things are optional.
8764 If no manual page is available, this is considered as a bug
8765 and should be reported to the Debian Bug Tracking System (the
8766 maintainer of the package is allowed to write this bug report
8767 themselves, if they so desire). Do not close the bug report
8768 until a proper man page is available.<footnote>
8769 It is not very hard to write a man page. See the
8770 <url id="http://www.schweikhardt.net/man_page_howto.html"
8771 name="Man-Page-HOWTO">,
8772 <manref name="man" section="7">, the examples
8773 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8774 the helper programs <prgn>help2man</prgn>, or the
8775 directory <file>/usr/share/doc/man-db/examples</file>.
8780 You may forward a complaint about a missing man page to the
8781 upstream authors, and mark the bug as forwarded in the
8782 Debian bug tracking system. Even though the GNU Project do
8783 not in general consider the lack of a man page to be a bug,
8784 we do; if they tell you that they don't consider it a bug
8785 you should leave the bug in our bug tracking system open
8790 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8794 If one man page needs to be accessible via several names it
8795 is better to use a symbolic link than the <file>.so</file>
8796 feature, but there is no need to fiddle with the relevant
8797 parts of the upstream source to change from <file>.so</file> to
8798 symlinks: don't do it unless it's easy. You should not
8799 create hard links in the manual page directories, nor put
8800 absolute filenames in <file>.so</file> directives. The filename
8801 in a <file>.so</file> in a man page should be relative to the
8802 base of the man page tree (usually
8803 <file>/usr/share/man</file>). If you do not create any links
8804 (whether symlinks, hard links, or <tt>.so</tt> directives)
8805 in the file system to the alternate names of the man page,
8806 then you should not rely on <prgn>man</prgn> finding your
8807 man page under those names based solely on the information in
8808 the man page's header.<footnote>
8809 Supporting this in <prgn>man</prgn> often requires
8810 unreasonable processing time to find a manual page or to
8811 report that none exists, and moves knowledge into man's
8812 database that would be better left in the file system.
8813 This support is therefore deprecated and will cease to
8814 be present in the future.
8819 Manual pages in locale-specific subdirectories of
8820 <file>/usr/share/man</file> should use either UTF-8 or the usual
8821 legacy encoding for that language (normally the one corresponding
8822 to the shortest relevant locale name in
8823 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8824 <file>/usr/share/man/fr</file> should use either UTF-8 or
8825 ISO-8859-1.<footnote>
8826 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8827 use. In future, all manual pages will be required to use
8833 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8834 included in the subdirectory name unless it indicates a
8835 significant difference in the language, as this excludes
8836 speakers of the language in other countries.<footnote>
8837 At the time of writing, Chinese and Portuguese are the main
8838 languages with such differences, so <file>pt_BR</file>,
8839 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8844 Due to limitations in current implementations, all characters
8845 in the manual page source should be representable in the usual
8846 legacy encoding for that language, even if the file is
8847 actually encoded in UTF-8. Safe alternative ways to write many
8848 characters outside that range may be found in
8849 <manref name="groff_char" section="7">.
8854 <heading>Info documents</heading>
8857 Info documents should be installed in <file>/usr/share/info</file>.
8858 They should be compressed with <tt>gzip -9</tt>.
8862 Your package should call <prgn>install-info</prgn> to update
8863 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8864 script when called with a <tt>configure</tt> argument, for
8866 <example compact="compact">
8867 install-info --quiet --section Development Development \
8868 /usr/share/info/foobar.info
8872 It is a good idea to specify a section for the location of
8873 your program; this is done with the <tt>--section</tt>
8874 switch. To determine which section to use, you should look
8875 at <file>/usr/share/info/dir</file> on your system and choose the most
8876 relevant (or create a new section if none of the current
8877 sections are relevant). Note that the <tt>--section</tt>
8878 flag takes two arguments; the first is a regular expression
8879 to match (case-insensitively) against an existing section,
8880 the second is used when creating a new one.</p>
8883 You should remove the entries in the <prgn>prerm</prgn>
8884 script when called with a <tt>remove</tt> argument:
8885 <example compact="compact">
8886 install-info --quiet --remove /usr/share/info/foobar.info
8890 If <prgn>install-info</prgn> cannot find a description entry
8891 in the Info file you must supply one. See <manref
8892 name="install-info" section="8"> for details.</p>
8896 <heading>Additional documentation</heading>
8899 Any additional documentation that comes with the package may
8900 be installed at the discretion of the package maintainer.
8901 Plain text documentation should be installed in the directory
8902 <file>/usr/share/doc/<var>package</var></file>, where
8903 <var>package</var> is the name of the package, and
8904 compressed with <tt>gzip -9</tt> unless it is small.
8908 If a package comes with large amounts of documentation which
8909 many users of the package will not require you should create
8910 a separate binary package to contain it, so that it does not
8911 take up disk space on the machines of users who do not need
8912 or want it installed.</p>
8915 It is often a good idea to put text information files
8916 (<file>README</file>s, changelogs, and so forth) that come with
8917 the source package in <file>/usr/share/doc/<var>package</var></file>
8918 in the binary package. However, you don't need to install
8919 the instructions for building and installing the package, of
8923 Packages must not require the existence of any files in
8924 <file>/usr/share/doc/</file> in order to function
8926 The system administrator should be able to
8927 delete files in <file>/usr/share/doc/</file> without causing
8928 any programs to break.
8930 Any files that are referenced by programs but are also
8931 useful as stand alone documentation should be installed under
8932 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8933 <file>/usr/share/doc/<var>package</var></file>.
8937 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8938 link to another directory in <file>/usr/share/doc</file> only if
8939 the two packages both come from the same source and the
8940 first package Depends on the second.<footnote>
8942 Please note that this does not override the section on
8943 changelog files below, so the file
8944 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8945 must refer to the changelog for the current version of
8946 <var>package</var> in question. In practice, this means
8947 that the sources of the target and the destination of the
8948 symlink must be the same (same source package and
8955 Former Debian releases placed all additional documentation
8956 in <file>/usr/doc/<var>package</var></file>. This has been
8957 changed to <file>/usr/share/doc/<var>package</var></file>,
8958 and packages must not put documentation in the directory
8959 <file>/usr/doc/<var>package</var></file>. <footnote>
8960 At this phase of the transition, we no longer require a
8961 symbolic link in <file>/usr/doc/</file>. At a later point,
8962 policy shall change to make the symbolic links a bug.
8968 <heading>Preferred documentation formats</heading>
8971 The unification of Debian documentation is being carried out
8975 If your package comes with extensive documentation in a
8976 markup format that can be converted to various other formats
8977 you should if possible ship HTML versions in a binary
8978 package, in the directory
8979 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8980 its subdirectories.<footnote>
8981 The rationale: The important thing here is that HTML
8982 docs should be available in <em>some</em> package, not
8983 necessarily in the main binary package.
8988 Other formats such as PostScript may be provided at the
8989 package maintainer's discretion.
8993 <sect id="copyrightfile">
8994 <heading>Copyright information</heading>
8997 Every package must be accompanied by a verbatim copy of its
8998 copyright and distribution license in the file
8999 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9000 file must neither be compressed nor be a symbolic link.
9004 In addition, the copyright file must say where the upstream
9005 sources (if any) were obtained. It should name the original
9006 authors of the package and the Debian maintainer(s) who were
9007 involved with its creation.
9011 Packages in the <em>contrib</em> or <em>non-free</em> archive
9012 areas should state in the copyright file that the package is not
9013 part of the Debian GNU/Linux distribution and briefly explain
9018 A copy of the file which will be installed in
9019 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9020 be in <file>debian/copyright</file> in the source package.
9024 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9025 link to another directory in <file>/usr/share/doc</file> only if
9026 the two packages both come from the same source and the
9027 first package Depends on the second. These rules are
9028 important because copyrights must be extractable by
9033 Packages distributed under the UCB BSD license, the Apache
9034 license (version 2.0), the Artistic license, the GNU GPL
9035 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9036 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9037 files under <file>/usr/share/common-licenses</file>,<footnote>
9040 <file>/usr/share/common-licenses/BSD</file>,
9041 <file>/usr/share/common-licenses/Apache-2.0</file>,
9042 <file>/usr/share/common-licenses/Artistic</file>,
9043 <file>/usr/share/common-licenses/GPL-2</file>,
9044 <file>/usr/share/common-licenses/GPL-3</file>,
9045 <file>/usr/share/common-licenses/LGPL-2</file>,
9046 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9047 <file>/usr/share/common-licenses/LGPL-3</file>,
9048 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9049 <file>/usr/share/common-licenses/GFDL-1.3</file>
9052 </footnote> rather than quoting them in the copyright
9057 You should not use the copyright file as a general <file>README</file>
9058 file. If your package has such a file it should be
9059 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9060 <file>README.Debian</file> or some other appropriate place.</p>
9064 <heading>Examples</heading>
9067 Any examples (configurations, source files, whatever),
9068 should be installed in a directory
9069 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9070 files should not be referenced by any program: they're there
9071 for the benefit of the system administrator and users as
9072 documentation only. Architecture-specific example files
9073 should be installed in a directory
9074 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9076 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9077 latter directory itself may be a symbolic link to the
9082 If the purpose of a package is to provide examples, then the
9083 example files may be installed into
9084 <file>/usr/share/doc/<var>package</var></file>.
9088 <sect id="changelogs">
9089 <heading>Changelog files</heading>
9092 Packages that are not Debian-native must contain a
9093 compressed copy of the <file>debian/changelog</file> file from
9094 the Debian source tree in
9095 <file>/usr/share/doc/<var>package</var></file> with the name
9096 <file>changelog.Debian.gz</file>.
9100 If an upstream changelog is available, it should be accessible as
9101 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9102 plain text. If the upstream changelog is distributed in
9103 HTML, it should be made available in that form as
9104 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9105 and a plain text <file>changelog.gz</file> should be generated
9106 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9107 the upstream changelog files do not already conform to this
9108 naming convention, then this may be achieved either by
9109 renaming the files, or by adding a symbolic link, at the
9110 maintainer's discretion.<footnote>
9111 Rationale: People should not have to look in places for
9112 upstream changelogs merely because they are given
9113 different names or are distributed in HTML format.
9118 All of these files should be installed compressed using
9119 <tt>gzip -9</tt>, as they will become large with time even
9120 if they start out small.
9124 If the package has only one changelog which is used both as
9125 the Debian changelog and the upstream one because there is
9126 no separate upstream maintainer then that changelog should
9127 usually be installed as
9128 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9129 there is a separate upstream maintainer, but no upstream
9130 changelog, then the Debian changelog should still be called
9131 <file>changelog.Debian.gz</file>.
9135 For details about the format and contents of the Debian
9136 changelog file, please see <ref id="dpkgchangelog">.
9141 <appendix id="pkg-scope">
9142 <heading>Introduction and scope of these appendices</heading>
9145 These appendices are taken essentially verbatim from the
9146 now-deprecated Packaging Manual, version 3.2.1.0. They are
9147 the chapters which are likely to be of use to package
9148 maintainers and which have not already been included in the
9149 policy document itself. Most of these sections are very likely
9150 not relevant to policy; they should be treated as
9151 documentation for the packaging system. Please note that these
9152 appendices are included for convenience, and for historical
9153 reasons: they used to be part of policy package, and they have
9154 not yet been incorporated into dpkg documentation. However,
9155 they still have value, and hence they are presented here.
9159 They have not yet been checked to ensure that they are
9160 compatible with the contents of policy, and if there are any
9161 contradictions, the version in the main policy document takes
9162 precedence. The remaining chapters of the old Packaging
9163 Manual have also not been read in detail to ensure that there
9164 are not parts which have been left out. Both of these will be
9169 Certain parts of the Packaging manual were integrated into the
9170 Policy Manual proper, and removed from the appendices. Links
9171 have been placed from the old locations to the new ones.
9175 <prgn>dpkg</prgn> is a suite of programs for creating binary
9176 package files and installing and removing them on Unix
9178 <prgn>dpkg</prgn> is targeted primarily at Debian
9179 GNU/Linux, but may work on or be ported to other
9185 The binary packages are designed for the management of
9186 installed executable programs (usually compiled binaries) and
9187 their associated data, though source code examples and
9188 documentation are provided as part of some packages.</p>
9191 This manual describes the technical aspects of creating Debian
9192 binary packages (<file>.deb</file> files). It documents the
9193 behavior of the package management programs
9194 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9195 they interact with packages.</p>
9198 It also documents the interaction between
9199 <prgn>dselect</prgn>'s core and the access method scripts it
9200 uses to actually install the selected packages, and describes
9201 how to create a new access method.</p>
9204 This manual does not go into detail about the options and
9205 usage of the package building and installation tools. It
9206 should therefore be read in conjunction with those programs'
9211 The utility programs which are provided with <prgn>dpkg</prgn>
9212 for managing various system configuration and similar issues,
9213 such as <prgn>update-rc.d</prgn> and
9214 <prgn>install-info</prgn>, are not described in detail here -
9215 please see their man pages.
9219 It is assumed that the reader is reasonably familiar with the
9220 <prgn>dpkg</prgn> System Administrators' manual.
9221 Unfortunately this manual does not yet exist.
9225 The Debian version of the FSF's GNU hello program is provided
9226 as an example for people wishing to create Debian
9227 packages. The Debian <prgn>debmake</prgn> package is
9228 recommended as a very helpful tool in creating and maintaining
9229 Debian packages. However, while the tools and examples are
9230 helpful, they do not replace the need to read and follow the
9231 Policy and Programmer's Manual.</p>
9234 <appendix id="pkg-binarypkg">
9235 <heading>Binary packages (from old Packaging Manual)</heading>
9238 The binary package has two main sections. The first part
9239 consists of various control information files and scripts used
9240 by <prgn>dpkg</prgn> when installing and removing. See <ref
9241 id="pkg-controlarea">.
9245 The second part is an archive containing the files and
9246 directories to be installed.
9250 In the future binary packages may also contain other
9251 components, such as checksums and digital signatures. The
9252 format for the archive is described in full in the
9253 <file>deb(5)</file> man page.
9257 <sect id="pkg-bincreating"><heading>Creating package files -
9258 <prgn>dpkg-deb</prgn>
9262 All manipulation of binary package files is done by
9263 <prgn>dpkg-deb</prgn>; it's the only program that has
9264 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9265 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9266 will spot that the options requested are appropriate to
9267 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9272 In order to create a binary package you must make a
9273 directory tree which contains all the files and directories
9274 you want to have in the file system data part of the package.
9275 In Debian-format source packages this directory is usually
9276 <file>debian/tmp</file>, relative to the top of the package's
9281 They should have the locations (relative to the root of the
9282 directory tree you're constructing) ownerships and
9283 permissions which you want them to have on the system when
9288 With current versions of <prgn>dpkg</prgn> the uid/username
9289 and gid/groupname mappings for the users and groups being
9290 used should be the same on the system where the package is
9291 built and the one where it is installed.
9295 You need to add one special directory to the root of the
9296 miniature file system tree you're creating:
9297 <prgn>DEBIAN</prgn>. It should contain the control
9298 information files, notably the binary package control file
9299 (see <ref id="pkg-controlfile">).
9303 The <prgn>DEBIAN</prgn> directory will not appear in the
9304 file system archive of the package, and so won't be installed
9305 by <prgn>dpkg</prgn> when the package is installed.
9309 When you've prepared the package, you should invoke:
9311 dpkg --build <var>directory</var>
9316 This will build the package in
9317 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9318 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9319 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9324 See the man page <manref name="dpkg-deb" section="8"> for details of how
9325 to examine the contents of this newly-created file. You may find the
9326 output of following commands enlightening:
9328 dpkg-deb --info <var>filename</var>.deb
9329 dpkg-deb --contents <var>filename</var>.deb
9330 dpkg --contents <var>filename</var>.deb
9332 To view the copyright file for a package you could use this command:
9334 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9339 <sect id="pkg-controlarea">
9340 <heading>Package control information files</heading>
9343 The control information portion of a binary package is a
9344 collection of files with names known to <prgn>dpkg</prgn>.
9345 It will treat the contents of these files specially - some
9346 of them contain information used by <prgn>dpkg</prgn> when
9347 installing or removing the package; others are scripts which
9348 the package maintainer wants <prgn>dpkg</prgn> to run.
9352 It is possible to put other files in the package control
9353 area, but this is not generally a good idea (though they
9354 will largely be ignored).
9358 Here is a brief list of the control info files supported by
9359 <prgn>dpkg</prgn> and a summary of what they're used for.
9364 <tag><tt>control</tt>
9367 This is the key description file used by
9368 <prgn>dpkg</prgn>. It specifies the package's name
9369 and version, gives its description for the user,
9370 states its relationships with other packages, and so
9371 forth. See <ref id="sourcecontrolfiles"> and
9372 <ref id="binarycontrolfiles">.
9376 It is usually generated automatically from information
9377 in the source package by the
9378 <prgn>dpkg-gencontrol</prgn> program, and with
9379 assistance from <prgn>dpkg-shlibdeps</prgn>.
9380 See <ref id="pkg-sourcetools">.
9384 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9389 These are executable files (usually scripts) which
9390 <prgn>dpkg</prgn> runs during installation, upgrade
9391 and removal of packages. They allow the package to
9392 deal with matters which are particular to that package
9393 or require more complicated processing than that
9394 provided by <prgn>dpkg</prgn>. Details of when and
9395 how they are called are in <ref id="maintainerscripts">.
9399 It is very important to make these scripts idempotent.
9400 See <ref id="idempotency">.
9404 The maintainer scripts are guaranteed to run with a
9405 controlling terminal and can interact with the user.
9406 See <ref id="controllingterminal">.
9410 <tag><tt>conffiles</tt>
9413 This file contains a list of configuration files which
9414 are to be handled automatically by <prgn>dpkg</prgn>
9415 (see <ref id="pkg-conffiles">). Note that not necessarily
9416 every configuration file should be listed here.
9419 <tag><tt>shlibs</tt>
9422 This file contains a list of the shared libraries
9423 supplied by the package, with dependency details for
9424 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9425 when it determines what dependencies are required in a
9426 package control file. The <tt>shlibs</tt> file format
9427 is described on <ref id="shlibs">.
9432 <sect id="pkg-controlfile">
9433 <heading>The main control information file: <tt>control</tt></heading>
9436 The most important control information file used by
9437 <prgn>dpkg</prgn> when it installs a package is
9438 <tt>control</tt>. It contains all the package's "vital
9443 The binary package control files of packages built from
9444 Debian sources are made by a special tool,
9445 <prgn>dpkg-gencontrol</prgn>, which reads
9446 <file>debian/control</file> and <file>debian/changelog</file> to
9447 find the information it needs. See <ref id="pkg-sourcepkg"> for
9452 The fields in binary package control files are listed in
9453 <ref id="binarycontrolfiles">.
9457 A description of the syntax of control files and the purpose
9458 of the fields is available in <ref id="controlfields">.
9463 <heading>Time Stamps</heading>
9466 See <ref id="timestamps">.
9471 <appendix id="pkg-sourcepkg">
9472 <heading>Source packages (from old Packaging Manual) </heading>
9475 The Debian binary packages in the distribution are generated
9476 from Debian sources, which are in a special format to assist
9477 the easy and automatic building of binaries.
9480 <sect id="pkg-sourcetools">
9481 <heading>Tools for processing source packages</heading>
9484 Various tools are provided for manipulating source packages;
9485 they pack and unpack sources and help build of binary
9486 packages and help manage the distribution of new versions.
9490 They are introduced and typical uses described here; see
9491 <manref name="dpkg-source" section="1"> for full
9492 documentation about their arguments and operation.
9496 For examples of how to construct a Debian source package,
9497 and how to use those utilities that are used by Debian
9498 source packages, please see the <prgn>hello</prgn> example
9502 <sect1 id="pkg-dpkg-source">
9504 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9509 This program is frequently used by hand, and is also
9510 called from package-independent automated building scripts
9511 such as <prgn>dpkg-buildpackage</prgn>.
9515 To unpack a package it is typically invoked with
9517 dpkg-source -x <var>.../path/to/filename</var>.dsc
9522 with the <file><var>filename</var>.tar.gz</file> and
9523 <file><var>filename</var>.diff.gz</file> (if applicable) in
9524 the same directory. It unpacks into
9525 <file><var>package</var>-<var>version</var></file>, and if
9527 <file><var>package</var>-<var>version</var>.orig</file>, in
9528 the current directory.
9532 To create a packed source archive it is typically invoked:
9534 dpkg-source -b <var>package</var>-<var>version</var>
9539 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9540 <file>.diff.gz</file> (if appropriate) in the current
9541 directory. <prgn>dpkg-source</prgn> does not clean the
9542 source tree first - this must be done separately if it is
9547 See also <ref id="pkg-sourcearchives">.</p>
9551 <sect1 id="pkg-dpkg-buildpackage">
9553 <prgn>dpkg-buildpackage</prgn> - overall package-building
9558 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9559 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9560 targets <tt>clean</tt>, <tt>build</tt> and
9561 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9562 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9563 source and binary package upload.
9567 It is usually invoked by hand from the top level of the
9568 built or unbuilt source directory. It may be invoked with
9569 no arguments; useful arguments include:
9570 <taglist compact="compact">
9571 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9574 Do not sign the <tt>.changes</tt> file or the
9575 source package <tt>.dsc</tt> file, respectively.</p>
9577 <tag><tt>-p<var>sign-command</var></tt></tag>
9580 Invoke <var>sign-command</var> instead of finding
9581 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9582 <var>sign-command</var> must behave just like
9583 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9585 <tag><tt>-r<var>root-command</var></tt></tag>
9588 When root privilege is required, invoke the command
9589 <var>root-command</var>. <var>root-command</var>
9590 should invoke its first argument as a command, from
9591 the <prgn>PATH</prgn> if necessary, and pass its
9592 second and subsequent arguments to the command it
9593 calls. If no <var>root-command</var> is supplied
9594 then <var>dpkg-buildpackage</var> will take no
9595 special action to gain root privilege, so that for
9596 most packages it will have to be invoked as root to
9599 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9602 Two types of binary-only build and upload - see
9603 <manref name="dpkg-source" section="1">.
9610 <sect1 id="pkg-dpkg-gencontrol">
9612 <prgn>dpkg-gencontrol</prgn> - generates binary package
9617 This program is usually called from <file>debian/rules</file>
9618 (see <ref id="pkg-sourcetree">) in the top level of the source
9623 This is usually done just before the files and directories in the
9624 temporary directory tree where the package is being built have their
9625 permissions and ownerships set and the package is constructed using
9626 <prgn>dpkg-deb/</prgn>
9628 This is so that the control file which is produced has
9629 the right permissions
9634 <prgn>dpkg-gencontrol</prgn> must be called after all the
9635 files which are to go into the package have been placed in
9636 the temporary build directory, so that its calculation of
9637 the installed size of a package is correct.
9641 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9642 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9643 variable substitutions created by
9644 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9649 For a package which generates only one binary package, and
9650 which builds it in <file>debian/tmp</file> relative to the top
9651 of the source package, it is usually sufficient to call
9652 <prgn>dpkg-gencontrol</prgn>.
9656 Sources which build several binaries will typically need
9659 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9660 </example> The <tt>-P</tt> tells
9661 <prgn>dpkg-gencontrol</prgn> that the package is being
9662 built in a non-default directory, and the <tt>-p</tt>
9663 tells it which package's control file should be generated.
9667 <prgn>dpkg-gencontrol</prgn> also adds information to the
9668 list of files in <file>debian/files</file>, for the benefit of
9669 (for example) a future invocation of
9670 <prgn>dpkg-genchanges</prgn>.</p>
9673 <sect1 id="pkg-dpkg-shlibdeps">
9675 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9680 This program is usually called from <file>debian/rules</file>
9681 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9682 id="pkg-sourcetree">), in the top level of the source tree.
9686 Its arguments are executables and shared libraries
9689 They may be specified either in the locations in the
9690 source tree where they are created or in the locations
9691 in the temporary build tree where they are installed
9692 prior to binary package creation.
9694 </footnote> for which shared library dependencies should
9695 be included in the binary package's control file.
9699 If some of the found shared libraries should only
9700 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9701 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9702 by using the <tt>-d<var>dependency-field</var></tt> option
9703 before those executable(s). (Each <tt>-d</tt> option
9704 takes effect until the next <tt>-d</tt>.)
9708 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9709 output control file to be modified. Instead by default it
9710 adds to the <file>debian/substvars</file> file variable
9711 settings like <tt>shlibs:Depends</tt>. These variable
9712 settings must be referenced in dependency fields in the
9713 appropriate per-binary-package sections of the source
9718 For example, a package that generates an essential part
9719 which requires dependencies, and optional parts that
9720 which only require a recommendation, would separate those
9721 two sets of dependencies into two different fields.<footnote>
9722 At the time of writing, an example for this was the
9723 <package/xmms/ package, with Depends used for the xmms
9724 executable, Recommends for the plug-ins and Suggests for
9725 even more optional features provided by unzip.
9727 It can say in its <file>debian/rules</file>:
9729 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9730 -dRecommends <var>optionalpart anotheroptionalpart</var>
9732 and then in its main control file <file>debian/control</file>:
9735 Depends: ${shlibs:Depends}
9736 Recommends: ${shlibs:Recommends}
9742 Sources which produce several binary packages with
9743 different shared library dependency requirements can use
9744 the <tt>-p<var>varnameprefix</var></tt> option to override
9745 the default <tt>shlibs:</tt> prefix (one invocation of
9746 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9747 They can thus produce several sets of dependency
9748 variables, each of the form
9749 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9750 which can be referred to in the appropriate parts of the
9751 binary package control files.
9756 <sect1 id="pkg-dpkg-distaddfile">
9758 <prgn>dpkg-distaddfile</prgn> - adds a file to
9759 <file>debian/files</file>
9763 Some packages' uploads need to include files other than
9764 the source and binary package files.
9768 <prgn>dpkg-distaddfile</prgn> adds a file to the
9769 <file>debian/files</file> file so that it will be included in
9770 the <file>.changes</file> file when
9771 <prgn>dpkg-genchanges</prgn> is run.
9775 It is usually invoked from the <tt>binary</tt> target of
9776 <file>debian/rules</file>:
9778 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9780 The <var>filename</var> is relative to the directory where
9781 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9782 is usually the directory above the top level of the source
9783 tree. The <file>debian/rules</file> target should put the
9784 file there just before or just after calling
9785 <prgn>dpkg-distaddfile</prgn>.
9789 The <var>section</var> and <var>priority</var> are passed
9790 unchanged into the resulting <file>.changes</file> file.
9795 <sect1 id="pkg-dpkg-genchanges">
9797 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9802 This program is usually called by package-independent
9803 automatic building scripts such as
9804 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9809 It is usually called in the top level of a built source
9810 tree, and when invoked with no arguments will print out a
9811 straightforward <file>.changes</file> file based on the
9812 information in the source package's changelog and control
9813 file and the binary and source packages which should have
9819 <sect1 id="pkg-dpkg-parsechangelog">
9821 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9822 representation of a changelog
9826 This program is used internally by
9827 <prgn>dpkg-source</prgn> et al. It may also occasionally
9828 be useful in <file>debian/rules</file> and elsewhere. It
9829 parses a changelog, <file>debian/changelog</file> by default,
9830 and prints a control-file format representation of the
9831 information in it to standard output.
9835 <sect1 id="pkg-dpkg-architecture">
9837 <prgn>dpkg-architecture</prgn> - information about the build and
9842 This program can be used manually, but is also invoked by
9843 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9844 environment or make variables which specify the build and host
9845 architecture for the package building process.
9850 <sect id="pkg-sourcetree">
9851 <heading>The Debianised source tree</heading>
9854 The source archive scheme described later is intended to
9855 allow a Debianised source tree with some associated control
9856 information to be reproduced and transported easily. The
9857 Debianised source tree is a version of the original program
9858 with certain files added for the benefit of the
9859 Debianisation process, and with any other changes required
9860 made to the rest of the source code and installation
9865 The extra files created for Debian are in the subdirectory
9866 <file>debian</file> of the top level of the Debianised source
9867 tree. They are described below.
9870 <sect1 id="pkg-debianrules">
9871 <heading><file>debian/rules</file> - the main building script</heading>
9874 See <ref id="debianrules">.
9879 <sect1 id="pkg-dpkgchangelog">
9880 <heading><file>debian/changelog</file></heading>
9883 See <ref id="dpkgchangelog">.
9886 <sect2><heading>Defining alternative changelog formats
9890 It is possible to use a different format to the standard
9891 one, by providing a parser for the format you wish to
9896 In order to have <tt>dpkg-parsechangelog</tt> run your
9897 parser, you must include a line within the last 40 lines
9898 of your file matching the Perl regular expression:
9899 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9900 parentheses should be the name of the format. For
9901 example, you might say:
9903 @@@ changelog-format: joebloggs @@@
9905 Changelog format names are non-empty strings of alphanumerics.
9909 If such a line exists then <tt>dpkg-parsechangelog</tt>
9910 will look for the parser as
9911 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9913 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9914 it is an error for it not to find it, or for it not to
9915 be an executable program. The default changelog format
9916 is <tt>dpkg</tt>, and a parser for it is provided with
9917 the <tt>dpkg</tt> package.
9921 The parser will be invoked with the changelog open on
9922 standard input at the start of the file. It should read
9923 the file (it may seek if it wishes) to determine the
9924 information required and return the parsed information
9925 to standard output in the form of a series of control
9926 fields in the standard format. By default it should
9927 return information about only the most recent version in
9928 the changelog; it should accept a
9929 <tt>-v<var>version</var></tt> option to return changes
9930 information from all versions present <em>strictly
9931 after</em> <var>version</var>, and it should then be an
9932 error for <var>version</var> not to be present in the
9938 <list compact="compact">
9939 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9940 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9941 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9942 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9943 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9944 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9945 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9950 If several versions are being returned (due to the use
9951 of <tt>-v</tt>), the urgency value should be of the
9952 highest urgency code listed at the start of any of the
9953 versions requested followed by the concatenated
9954 (space-separated) comments from all the versions
9955 requested; the maintainer, version, distribution and
9956 date should always be from the most recent version.
9960 For the format of the <tt>Changes</tt> field see
9961 <ref id="f-Changes">.
9965 If the changelog format which is being parsed always or
9966 almost always leaves a blank line between individual
9967 change notes these blank lines should be stripped out,
9968 so as to make the resulting output compact.
9972 If the changelog format does not contain date or package
9973 name information this information should be omitted from
9974 the output. The parser should not attempt to synthesize
9975 it or find it from other sources.
9979 If the changelog does not have the expected format the
9980 parser should exit with a nonzero exit status, rather
9981 than trying to muddle through and possibly generating
9986 A changelog parser may not interact with the user at
9992 <sect1 id="pkg-srcsubstvars">
9993 <heading><file>debian/substvars</file> and variable substitutions</heading>
9996 See <ref id="substvars">.
10002 <heading><file>debian/files</file></heading>
10005 See <ref id="debianfiles">.
10009 <sect1><heading><file>debian/tmp</file>
10013 This is the canonical temporary location for the
10014 construction of binary packages by the <tt>binary</tt>
10015 target. The directory <file>tmp</file> serves as the root of
10016 the file system tree as it is being constructed (for
10017 example, by using the package's upstream makefiles install
10018 targets and redirecting the output there), and it also
10019 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10020 id="pkg-bincreating">.
10024 If several binary packages are generated from the same
10025 source tree it is usual to use several
10026 <file>debian/tmp<var>something</var></file> directories, for
10027 example <file>tmp-a</file> or <file>tmp-doc</file>.
10031 Whatever <file>tmp</file> directories are created and used by
10032 <tt>binary</tt> must of course be removed by the
10033 <tt>clean</tt> target.</p></sect1>
10037 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10041 As it exists on the FTP site, a Debian source package
10042 consists of three related files. You must have the right
10043 versions of all three to be able to use them.
10048 <tag>Debian source control file - <tt>.dsc</tt></tag>
10050 This file is a control file used by <prgn>dpkg-source</prgn>
10051 to extract a source package.
10052 See <ref id="debiansourcecontrolfiles">.
10056 Original source archive -
10058 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10064 This is a compressed (with <tt>gzip -9</tt>)
10065 <prgn>tar</prgn> file containing the source code from
10066 the upstream authors of the program.
10071 Debianisation diff -
10073 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10079 This is a unified context diff (<tt>diff -u</tt>)
10080 giving the changes which are required to turn the
10081 original source into the Debian source. These changes
10082 may only include editing and creating plain files.
10083 The permissions of files, the targets of symbolic
10084 links and the characteristics of special files or
10085 pipes may not be changed and no files may be removed
10090 All the directories in the diff must exist, except the
10091 <file>debian</file> subdirectory of the top of the source
10092 tree, which will be created by
10093 <prgn>dpkg-source</prgn> if necessary when unpacking.
10097 The <prgn>dpkg-source</prgn> program will
10098 automatically make the <file>debian/rules</file> file
10099 executable (see below).</p></item>
10104 If there is no original source code - for example, if the
10105 package is specially prepared for Debian or the Debian
10106 maintainer is the same as the upstream maintainer - the
10107 format is slightly different: then there is no diff, and the
10109 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10110 and preferably contains a directory named
10111 <file><var>package</var>-<var>version</var></file>.
10116 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10119 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10120 Debian source package. However, if it is not available it
10121 is possible to unpack a Debian source archive as follows:
10122 <enumlist compact="compact">
10125 Untar the tarfile, which will create a <file>.orig</file>
10129 <p>Rename the <file>.orig</file> directory to
10130 <file><var>package</var>-<var>version</var></file>.</p>
10134 Create the subdirectory <file>debian</file> at the top of
10135 the source tree.</p>
10137 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10139 <item><p>Untar the tarfile again if you want a copy of the original
10140 source code alongside the Debianised version.</p>
10145 It is not possible to generate a valid Debian source archive
10146 without using <prgn>dpkg-source</prgn>. In particular,
10147 attempting to use <prgn>diff</prgn> directly to generate the
10148 <file>.diff.gz</file> file will not work.
10152 <heading>Restrictions on objects in source packages</heading>
10155 The source package may not contain any hard links
10157 This is not currently detected when building source
10158 packages, but only when extracting
10162 Hard links may be permitted at some point in the
10163 future, but would require a fair amount of
10165 </footnote>, device special files, sockets or setuid or
10168 Setgid directories are allowed.
10173 The source packaging tools manage the changes between the
10174 original and Debianised source using <prgn>diff</prgn> and
10175 <prgn>patch</prgn>. Turning the original source tree as
10176 included in the <file>.orig.tar.gz</file> into the debianised
10177 source must not involve any changes which cannot be
10178 handled by these tools. Problematic changes which cause
10179 <prgn>dpkg-source</prgn> to halt with an error when
10180 building the source package are:
10181 <list compact="compact">
10182 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10184 <item><p>Changing the targets of symbolic links.</p>
10186 <item><p>Creating directories, other than <file>debian</file>.</p>
10188 <item><p>Changes to the contents of binary files.</p></item>
10189 </list> Changes which cause <prgn>dpkg-source</prgn> to
10190 print a warning but continue anyway are:
10191 <list compact="compact">
10194 Removing files, directories or symlinks.
10196 Renaming a file is not treated specially - it is
10197 seen as the removal of the old file (which
10198 generates a warning, but is otherwise ignored),
10199 and the creation of the new one.
10205 Changed text files which are missing the usual final
10206 newline (either in the original or the modified
10211 Changes which are not represented, but which are not detected by
10212 <prgn>dpkg-source</prgn>, are:
10213 <list compact="compact">
10214 <item><p>Changing the permissions of files (other than
10215 <file>debian/rules</file>) and directories.</p></item>
10220 The <file>debian</file> directory and <file>debian/rules</file>
10221 are handled specially by <prgn>dpkg-source</prgn> - before
10222 applying the changes it will create the <file>debian</file>
10223 directory, and afterwards it will make
10224 <file>debian/rules</file> world-executable.
10230 <appendix id="pkg-controlfields">
10231 <heading>Control files and their fields (from old Packaging Manual)</heading>
10234 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10235 data in a common format, known as control files. Binary and
10236 source packages have control data as do the <file>.changes</file>
10237 files which control the installation of uploaded files, and
10238 <prgn>dpkg</prgn>'s internal databases are in a similar
10243 <heading>Syntax of control files</heading>
10246 See <ref id="controlsyntax">.
10250 It is important to note that there are several fields which
10251 are optional as far as <prgn>dpkg</prgn> and the related
10252 tools are concerned, but which must appear in every Debian
10253 package, or whose omission may cause problems.
10258 <heading>List of fields</heading>
10261 See <ref id="controlfieldslist">.
10265 This section now contains only the fields that didn't belong
10266 to the Policy manual.
10269 <sect1 id="pkg-f-Filename">
10270 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10273 These fields in <tt>Packages</tt> files give the
10274 filename(s) of (the parts of) a package in the
10275 distribution directories, relative to the root of the
10276 Debian hierarchy. If the package has been split into
10277 several parts the parts are all listed in order, separated
10282 <sect1 id="pkg-f-Size">
10283 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10286 These fields in <file>Packages</file> files give the size (in
10287 bytes, expressed in decimal) and MD5 checksum of the
10288 file(s) which make(s) up a binary package in the
10289 distribution. If the package is split into several parts
10290 the values for the parts are listed in order, separated by
10295 <sect1 id="pkg-f-Status">
10296 <heading><tt>Status</tt></heading>
10299 This field in <prgn>dpkg</prgn>'s status file records
10300 whether the user wants a package installed, removed or
10301 left alone, whether it is broken (requiring
10302 re-installation) or not and what its current state on the
10303 system is. Each of these pieces of information is a
10308 <sect1 id="pkg-f-Config-Version">
10309 <heading><tt>Config-Version</tt></heading>
10312 If a package is not installed or not configured, this
10313 field in <prgn>dpkg</prgn>'s status file records the last
10314 version of the package which was successfully
10319 <sect1 id="pkg-f-Conffiles">
10320 <heading><tt>Conffiles</tt></heading>
10323 This field in <prgn>dpkg</prgn>'s status file contains
10324 information about the automatically-managed configuration
10325 files held by a package. This field should <em>not</em>
10326 appear anywhere in a package!
10331 <heading>Obsolete fields</heading>
10334 These are still recognized by <prgn>dpkg</prgn> but should
10335 not appear anywhere any more.
10337 <taglist compact="compact">
10339 <tag><tt>Revision</tt></tag>
10340 <tag><tt>Package-Revision</tt></tag>
10341 <tag><tt>Package_Revision</tt></tag>
10343 The Debian revision part of the package version was
10344 at one point in a separate control file field. This
10345 field went through several names.
10348 <tag><tt>Recommended</tt></tag>
10349 <item>Old name for <tt>Recommends</tt>.</item>
10351 <tag><tt>Optional</tt></tag>
10352 <item>Old name for <tt>Suggests</tt>.</item>
10354 <tag><tt>Class</tt></tag>
10355 <item>Old name for <tt>Priority</tt>.</item>
10364 <appendix id="pkg-conffiles">
10365 <heading>Configuration file handling (from old Packaging Manual)</heading>
10368 <prgn>dpkg</prgn> can do a certain amount of automatic
10369 handling of package configuration files.
10373 Whether this mechanism is appropriate depends on a number of
10374 factors, but basically there are two approaches to any
10375 particular configuration file.
10379 The easy method is to ship a best-effort configuration in the
10380 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10381 handle updates. If the user is unlikely to want to edit the
10382 file, but you need them to be able to without losing their
10383 changes, and a new package with a changed version of the file
10384 is only released infrequently, this is a good approach.
10388 The hard method is to build the configuration file from
10389 scratch in the <prgn>postinst</prgn> script, and to take the
10390 responsibility for fixing any mistakes made in earlier
10391 versions of the package automatically. This will be
10392 appropriate if the file is likely to need to be different on
10396 <sect><heading>Automatic handling of configuration files by
10401 A package may contain a control area file called
10402 <tt>conffiles</tt>. This file should be a list of filenames
10403 of configuration files needing automatic handling, separated
10404 by newlines. The filenames should be absolute pathnames,
10405 and the files referred to should actually exist in the
10410 When a package is upgraded <prgn>dpkg</prgn> will process
10411 the configuration files during the configuration stage,
10412 shortly before it runs the package's <prgn>postinst</prgn>
10417 For each file it checks to see whether the version of the
10418 file included in the package is the same as the one that was
10419 included in the last version of the package (the one that is
10420 being upgraded from); it also compares the version currently
10421 installed on the system with the one shipped with the last
10426 If neither the user nor the package maintainer has changed
10427 the file, it is left alone. If one or the other has changed
10428 their version, then the changed version is preferred - i.e.,
10429 if the user edits their file, but the package maintainer
10430 doesn't ship a different version, the user's changes will
10431 stay, silently, but if the maintainer ships a new version
10432 and the user hasn't edited it the new version will be
10433 installed (with an informative message). If both have
10434 changed their version the user is prompted about the problem
10435 and must resolve the differences themselves.
10439 The comparisons are done by calculating the MD5 message
10440 digests of the files, and storing the MD5 of the file as it
10441 was included in the most recent version of the package.
10445 When a package is installed for the first time
10446 <prgn>dpkg</prgn> will install the file that comes with it,
10447 unless that would mean overwriting a file already on the
10452 However, note that <prgn>dpkg</prgn> will <em>not</em>
10453 replace a conffile that was removed by the user (or by a
10454 script). This is necessary because with some programs a
10455 missing file produces an effect hard or impossible to
10456 achieve in another way, so that a missing file needs to be
10457 kept that way if the user did it.
10461 Note that a package should <em>not</em> modify a
10462 <prgn>dpkg</prgn>-handled conffile in its maintainer
10463 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10464 the user confusing and possibly dangerous options for
10465 conffile update when the package is upgraded.</p>
10468 <sect><heading>Fully-featured maintainer script configuration
10473 For files which contain site-specific information such as
10474 the hostname and networking details and so forth, it is
10475 better to create the file in the package's
10476 <prgn>postinst</prgn> script.
10480 This will typically involve examining the state of the rest
10481 of the system to determine values and other information, and
10482 may involve prompting the user for some information which
10483 can't be obtained some other way.
10487 When using this method there are a couple of important
10488 issues which should be considered:
10492 If you discover a bug in the program which generates the
10493 configuration file, or if the format of the file changes
10494 from one version to the next, you will have to arrange for
10495 the postinst script to do something sensible - usually this
10496 will mean editing the installed configuration file to remove
10497 the problem or change the syntax. You will have to do this
10498 very carefully, since the user may have changed the file,
10499 perhaps to fix the very problem that your script is trying
10500 to deal with - you will have to detect these situations and
10501 deal with them correctly.
10505 If you do go down this route it's probably a good idea to
10506 make the program that generates the configuration file(s) a
10507 separate program in <file>/usr/sbin</file>, by convention called
10508 <file><var>package</var>config</file> and then run that if
10509 appropriate from the post-installation script. The
10510 <tt><var>package</var>config</tt> program should not
10511 unquestioningly overwrite an existing configuration - if its
10512 mode of operation is geared towards setting up a package for
10513 the first time (rather than any arbitrary reconfiguration
10514 later) you should have it check whether the configuration
10515 already exists, and require a <tt>--force</tt> flag to
10516 overwrite it.</p></sect>
10519 <appendix id="pkg-alternatives"><heading>Alternative versions of
10520 an interface - <prgn>update-alternatives</prgn> (from old
10525 When several packages all provide different versions of the
10526 same program or file it is useful to have the system select a
10527 default, but to allow the system administrator to change it
10528 and have their decisions respected.
10532 For example, there are several versions of the <prgn>vi</prgn>
10533 editor, and there is no reason to prevent all of them from
10534 being installed at once, each under their own name
10535 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10536 Nevertheless it is desirable to have the name <tt>vi</tt>
10537 refer to something, at least by default.
10541 If all the packages involved cooperate, this can be done with
10542 <prgn>update-alternatives</prgn>.
10546 Each package provides its own version under its own name, and
10547 calls <prgn>update-alternatives</prgn> in its postinst to
10548 register its version (and again in its prerm to deregister
10553 See the man page <manref name="update-alternatives"
10554 section="8"> for details.
10558 If <prgn>update-alternatives</prgn> does not seem appropriate
10559 you may wish to consider using diversions instead.</p>
10562 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10563 package's version of a file (from old Packaging Manual)
10567 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10568 when it reinstalls the package it belongs to, and to have it
10569 put the file from the package somewhere else instead.
10573 This can be used locally to override a package's version of a
10574 file, or by one package to override another's version (or
10575 provide a wrapper for it).
10579 Before deciding to use a diversion, read <ref
10580 id="pkg-alternatives"> to see if you really want a diversion
10581 rather than several alternative versions of a program.
10585 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10586 and updated by a special program <prgn>dpkg-divert</prgn>.
10587 Please see <manref name="dpkg-divert" section="8"> for full
10588 details of its operation.
10592 When a package wishes to divert a file from another, it should
10593 call <prgn>dpkg-divert</prgn> in its preinst to add the
10594 diversion and rename the existing file. For example,
10595 supposing that a <prgn>smailwrapper</prgn> package wishes to
10596 install a wrapper around <file>/usr/sbin/smail</file>:
10598 dpkg-divert --package smailwrapper --add --rename \
10599 --divert /usr/sbin/smail.real /usr/sbin/smail
10600 </example> The <tt>--package smailwrapper</tt> ensures that
10601 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10602 can bypass the diversion and get installed as the true version.
10603 It's safe to add the diversion unconditionally on upgrades since
10604 it will be left unchanged if it already exists, but
10605 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10606 message, make the command conditional on the version from which
10607 the package is being upgraded:
10609 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10610 dpkg-divert --package smailwrapper --add --rename \
10611 --divert /usr/sbin/smail.real /usr/sbin/smail
10613 </example> where <tt>1.0-2</tt> is the version at which the
10614 diversion was first added to the package. Running the command
10615 during abort-upgrade is pointless but harmless.
10619 The postrm has to do the reverse:
10621 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10622 dpkg-divert --package smailwrapper --remove --rename \
10623 --divert /usr/sbin/smail.real /usr/sbin/smail
10625 </example> If the diversion was added at a particular version, the
10626 postrm should also handle the failure case of upgrading from an
10627 older version (unless the older version is so old that direct
10628 upgrades are no longer supported):
10630 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10631 dpkg-divert --package smailwrapper --remove --rename \
10632 --divert /usr/sbin/smail.real /usr/sbin/smail
10634 </example> where <tt>1.02-2</tt> is the version at which the
10635 diversion was first added to the package. The postrm should not
10636 remove the diversion on upgrades both because there's no reason to
10637 remove the diversion only to immediately re-add it and since the
10638 postrm of the old package is run after unpacking so the removal of
10639 the diversion will fail.
10643 Do not attempt to divert a file which is vitally important for
10644 the system's operation - when using <prgn>dpkg-divert</prgn>
10645 there is a time, after it has been diverted but before
10646 <prgn>dpkg</prgn> has installed the new version, when the file
10647 does not exist.</p>
10652 <!-- Local variables: -->
10653 <!-- indent-tabs-mode: t -->
10655 <!-- vim:set ai et sts=2 sw=2 tw=76: -->