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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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" id="http://packages.debian.org/debian-policy"></package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>.
168 Also available from the same directory are several other
169 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
170 and <file>policy.ps.gz</file>.
174 The <package>debian-policy</package> package also includes the file
175 <file>upgrading-checklist.txt</file> which indicates policy
176 changes between versions of this document.
181 <heading>Authors and Maintainers</heading>
184 Originally called "Debian GNU/Linux Policy Manual", this
185 manual was initially written in 1996 by Ian Jackson.
186 It was revised on November 27th, 1996 by David A. Morris.
187 Christian Schwarz added new sections on March 15th, 1997,
188 and reworked/restructured it in April-July 1997.
189 Christoph Lameter contributed the "Web Standard".
190 Julian Gilbey largely restructured it in 2001.
194 Since September 1998, the responsibility for the contents of
195 this document lies on the <url name="debian-policy mailing list"
196 id="mailto:debian-policy@lists.debian.org">. Proposals
197 are discussed there and inserted into policy after a certain
198 consensus is established.
199 <!-- insert shameless policy-process plug here eventually -->
200 The actual editing is done by a group of maintainers that have
201 no editorial powers. These are the current maintainers:
204 <item>Julian Gilbey</item>
205 <item>Branden Robinson</item>
206 <item>Josip Rodin</item>
207 <item>Manoj Srivastava</item>
212 While the authors of this document have tried hard to avoid
213 typos and other errors, these do still occur. If you discover
214 an error in this manual or if you want to give any
215 comments, suggestions, or criticisms please send an email to
216 the Debian Policy List,
217 <email>debian-policy@lists.debian.org</email>, or submit a
218 bug report against the <tt>debian-policy</tt> package.
222 Please do not try to reach the individual authors or maintainers
223 of the Policy Manual regarding changes to the Policy.
228 <heading>Related documents</heading>
231 There are several other documents other than this Policy Manual
232 that are necessary to fully understand some Debian policies and
237 The external "sub-policy" documents are referred to in:
238 <list compact="compact">
239 <item><ref id="fhs"></item>
240 <item><ref id="virtual_pkg"></item>
241 <item><ref id="menus"></item>
242 <item><ref id="mime"></item>
243 <item><ref id="perl"></item>
244 <item><ref id="maintscriptprompt"></item>
245 <item><ref id="emacs"></item>
250 In addition to those, which carry the weight of policy, there
251 is the Debian Developer's Reference. This document describes
252 procedures and resources for Debian developers, but it is
253 <em>not</em> normative; rather, it includes things that don't
254 belong into the Policy, such as best practices for developers.
258 The Developer's Reference is available in the
259 <package>developers-reference</package> package.
260 It's also available from the Debian web mirrors at
261 <tt><url name="/doc/developers-reference/"
262 id="http://www.debian.org/doc/developers-reference/"></tt>.
270 <heading>The Debian Archive</heading>
273 The Debian GNU/Linux system is maintained and distributed as a
274 collection of <em>packages</em>. Since there are so many of
275 them (currently well over 6000), they are split into
276 <em>sections</em> and given <em>priorities</em> to simplify
277 the handling of them.
281 The effort of the Debian project is to build a free operating
282 system, but not every package we want to make accessible is
283 <em>free</em> in our sense (see the Debian Free Software
284 Guidelines, below), or may be imported/exported without
285 restrictions. Thus, the archive is split into the sections
286 based on their licenses and other restrictions.
290 The aims of this are:
292 <list compact="compact">
293 <item>to allow us to make as much software available as we can</item>
294 <item>to allow us to encourage everyone to write free software,
296 <item>to allow us to make it easy for people to produce
297 CD-ROMs of our system without violating any licenses,
298 import/export restrictions, or any other laws.</item>
303 The <em>main</em> and the <em>non-US/main</em> sections
304 together form the <em>Debian GNU/Linux distribution</em>.
308 Packages in the other sections are not considered to be part
309 of the Debian distribution, although we support their use and
310 provide infrastructure for them (such as our bug-tracking
311 system and mailing lists). This Debian Policy Manual applies
312 to these packages as well.
316 <heading>The Debian Free Software Guidelines</heading>
318 The Debian Free Software Guidelines (DFSG) form our
319 definition of "free software". These are:
321 <tag>Free Redistribution
324 The license of a Debian component may not restrict any
325 party from selling or giving away the software as a
326 component of an aggregate software distribution
327 containing programs from several different
328 sources. The license may not require a royalty or
329 other fee for such sale.
334 The program must include source code, and must allow
335 distribution in source code as well as compiled form.
340 The license must allow modifications and derived
341 works, and must allow them to be distributed under the
342 same terms as the license of the original software.
344 <tag>Integrity of The Author's Source Code
347 The license may restrict source-code from being
348 distributed in modified form <em>only</em> if the
349 license allows the distribution of "patch files"
350 with the source code for the purpose of modifying the
351 program at build time. The license must explicitly
352 permit distribution of software built from modified
353 source code. The license may require derived works to
354 carry a different name or version number from the
355 original software. (This is a compromise. The Debian
356 Project encourages all authors to not restrict any
357 files, source or binary, from being modified.)
359 <tag>No Discrimination Against Persons or Groups
362 The license must not discriminate against any person
365 <tag>No Discrimination Against Fields of Endeavor
368 The license must not restrict anyone from making use
369 of the program in a specific field of endeavor. For
370 example, it may not restrict the program from being
371 used in a business, or from being used for genetic
374 <tag>Distribution of License
377 The rights attached to the program must apply to all
378 to whom the program is redistributed without the need
379 for execution of an additional license by those
382 <tag>License Must Not Be Specific to Debian
385 The rights attached to the program must not depend on
386 the program's being part of a Debian system. If the
387 program is extracted from Debian and used or
388 distributed without Debian but otherwise within the
389 terms of the program's license, all parties to whom
390 the program is redistributed must have the same
391 rights as those that are granted in conjunction with
394 <tag>License Must Not Contaminate Other Software
397 The license must not place restrictions on other
398 software that is distributed along with the licensed
399 software. For example, the license must not insist
400 that all other programs distributed on the same medium
401 must be free software.
403 <tag>Example Licenses
406 The "GPL," "BSD," and "Artistic" licenses are examples of
407 licenses that we consider <em>free</em>.
414 <heading>Sections</heading>
417 <heading>The main section</heading>
420 Every package in <em>main</em> and <em>non-US/main</em>
421 must comply with the DFSG (Debian Free Software
426 In addition, the packages in <em>main</em>
427 <list compact="compact">
429 must not require a package outside of <em>main</em>
430 for compilation or execution (thus, the package must
431 not declare a "Depends", "Recommends", or
432 "Build-Depends" relationship on a non-<em>main</em>
436 must not be so buggy that we refuse to support them,
440 must meet all policy requirements presented in this
447 Similarly, the packages in <em>non-US/main</em>
448 <list compact="compact">
450 must not require a package outside of <em>main</em>
451 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
458 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
479 must not be so buggy that we refuse to support them,
483 must meet all policy requirements presented in this
490 Furthermore, packages in <em>contrib</em> must not require
491 a package in a <em>non-US</em> section for compilation or
496 Examples of packages which would be included in
497 <em>contrib</em> or <em>non-US/contrib</em> are:
498 <list compact="compact">
500 free packages which require <em>contrib</em>,
501 <em>non-free</em> packages or packages which are not
502 in our archive at all for compilation or execution,
506 wrapper packages or other sorts of free accessories for
513 <sect1 id="non-free">
514 <heading>The non-free section</heading>
517 Packages must be placed in <em>non-free</em> or
518 <em>non-US/non-free</em> if they are not compliant with
519 the DFSG or are encumbered by patents or other legal
520 issues that make their distribution problematic.
524 In addition, the packages in <em>non-free</em> and
525 <em>non-US/non-free</em>
526 <list compact="compact">
528 must not be so buggy that we refuse to support them,
532 must meet all policy requirements presented in this
533 manual that it is possible for them to meet.
535 It is possible that there are policy
536 requirements which the package is unable to
537 meet, for example, if the source is
538 unavailable. These situations will need to be
539 handled on a case-by-case basis.
547 <heading>The non-US sections</heading>
550 Non-free programs with cryptographic program code need to
551 be stored on the <em>non-us</em> server because of export
552 restrictions of the U.S.
556 Programs which use patented algorithms that have a
557 restricted license also need to be stored on "non-us",
558 since that is located in a country where it is not allowed
559 to patent algorithms.
563 A package depends on another package which is distributed
564 via the non-us server has to be stored on the non-us
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of
575 its copyright and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Subsections</heading>
653 The packages in the sections <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further
655 into <em>subsections</em> to simplify handling.
659 The section and subsection for each package should be
660 specified in the package's <tt>Section</tt> control
661 record (see <ref id="f-Section">).
662 However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
668 <em>subsection</em> if the package is in the
669 <em>main</em> section,
672 <em>section/subsection</em> if the package is in
673 the <em>contrib</em> or <em>non-free</em> section,
677 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
678 <tt>non-US/non-free</tt> if the package is in
679 <em>non-US/main</em>, <em>non-US/contrib</em> or
680 <em>non-US/non-free</em> respectively.
686 The Debian archive maintainers provide the authoritative
687 list of subsections. At present, they are:
688 <em>admin</em>, <em>base</em>, <em>comm</em>,
689 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
690 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
691 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
692 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
693 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
694 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
695 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
696 <em>otherosfs</em>, <em>perl</em>, <em>python</em>
697 <em>science</em>, <em>shells</em>,
698 <em>sound</em>, <em>tex</em>, <em>text</em>,
699 <em>utils</em>, <em>web</em>, <em>x11</em>.
703 <sect id="priorities">
704 <heading>Priorities</heading>
707 Each package should have a <em>priority</em> value, which is
708 included in the package's <em>control record</em>
709 (see <ref id="f-Priority">).
710 This information is used by the Debian package management tools to
711 separate high-priority packages from less-important packages.
715 The following <em>priority levels</em> are recognised by the
716 Debian package management tools.
718 <tag><tt>required</tt></tag>
720 Packages which are necessary for the proper
721 functioning of the system. You must not remove these
722 packages or your system may become totally broken and
723 you may not even be able to use <prgn>dpkg</prgn> to
724 put things back. Systems with only the
725 <tt>required</tt> packages are probably unusable, but
726 they do have enough functionality to allow the
727 sysadmin to boot and install more software.
729 <tag><tt>important</tt></tag>
731 Important programs, including those which one would
732 expect to find on any Unix-like system. If the
733 expectation is that an experienced Unix person who
734 found it missing would say "What on earth is going on,
735 where is <prgn>foo</prgn>?", it must be an
736 <tt>important</tt> package.<footnote>
737 This is an important criterion because we are
738 trying to produce, amongst other things, a free
741 Other packages without which the system will not run
742 well or be usable must also have priority
743 <tt>important</tt>. This does
744 <em>not</em> include Emacs, the X Window System, TeX
745 or any other large applications. The
746 <tt>important</tt> packages are just a bare minimum of
747 commonly-expected and necessary tools.
749 <tag><tt>standard</tt></tag>
751 These packages provide a reasonably small but not too
752 limited character-mode system. This is what will be
753 installed by default if the user doesn't select anything
754 else. It doesn't include many large applications.
756 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
767 <tag><tt>extra</tt></tag>
769 This contains all packages that conflict with others
770 with required, important, standard or optional
771 priorities, or are only likely to be useful if you
772 already know what they are or have specialised
779 Packages must not depend on packages with lower priority
780 values (excluding build-time dependencies). In order to
781 ensure this, the priorities of one or more packages may need
790 <heading>Binary packages</heading>
793 The Debian GNU/Linux distribution is based on the Debian
794 package management system, called <prgn>dpkg</prgn>. Thus,
795 all packages in the Debian distribution must be provided
796 in the <tt>.deb</tt> file format.
800 <heading>The package name</heading>
803 Every package must have a name that's unique within the Debian
808 The package name is included in the control field
809 <tt>Package</tt>, the format of which is described
810 in <ref id="f-Package">.
811 The package name is also included as a part of the file name
812 of the <tt>.deb</tt> file.
817 <heading>The version of a package</heading>
820 Every package has a version number recorded in its
821 <tt>Version</tt> control file field, described in
822 <ref id="f-Version">.
826 The package management system imposes an ordering on version
827 numbers, so that it can tell whether packages are being up- or
828 downgraded and so that package system front end applications
829 can tell whether a package it finds available is newer than
830 the one installed on the system. The version number format
831 has the most significant parts (as far as comparison is
832 concerned) at the beginning.
836 If an upstream package has problematic version numbers they
837 should be converted to a sane form for use in the
838 <tt>Version</tt> field.
842 <heading>Version numbers based on dates</heading>
845 In general, Debian packages should use the same version
846 numbers as the upstream sources.
850 However, in some cases where the upstream version number is
851 based on a date (e.g., a development "snapshot" release) the
852 package management system cannot handle these version
853 numbers without epochs. For example, dpkg will consider
854 "96May01" to be greater than "96Dec24".
858 To prevent having to use epochs for every new upstream
859 version, the version number should be changed to the
860 following format in such cases: "19960501", "19961224". It
861 is up to the maintainer whether he/she wants to bother the
862 upstream maintainer to change the version numbers upstream,
867 Note that other version formats based on dates which are
868 parsed correctly by the package management system should
869 <em>not</em> be changed.
873 Native Debian packages (i.e., packages which have been
874 written especially for Debian) whose version numbers include
875 dates should always use the "YYYYMMDD" format.
882 <heading>The maintainer of a package</heading>
885 Every package must have a Debian maintainer (the
886 maintainer may be one person or a group of people
887 reachable from a common email address, such as a mailing
888 list). The maintainer is responsible for ensuring that
889 the package is placed in the appropriate distributions.
893 The maintainer must be specified in the
894 <tt>Maintainer</tt> control field with their correct name
895 and a working email address. If one person maintains
896 several packages, he/she should try to avoid having
897 different forms of their name and email address in
898 the <tt>Maintainer</tt> fields of those packages.
902 The format of the <tt>Maintainer</tt> control field is
903 described in <ref id="f-Maintainer">.
907 If the maintainer of a package quits from the Debian
908 project, "Debian QA Group"
909 <email>packages@qa.debian.org</email> takes over the
910 maintainership of the package until someone else
911 volunteers for that task. These packages are called
912 <em>orphaned packages</em>.<footnote>
913 The detailed procedure for doing this gracefully can
914 be found in the Debian Developer's Reference,
915 see <ref id="related">.
920 <sect id="descriptions">
921 <heading>The description of a package</heading>
924 Every Debian package must have an extended description
925 stored in the appropriate field of the control record.
926 The technical information about the format of the
927 <tt>Description</tt> field is in <ref id="f-Description">.
931 The description should describe the package (the program) to a
932 user (system administrator) who has never met it before so that
933 they have enough information to decide whether they want to
934 install it. This description should not just be copied verbatim
935 from the program's documentation.
939 Put important information first, both in the synopsis and
940 extended description. Sometimes only the first part of the
941 synopsis or of the description will be displayed. You can
942 assume that there will usually be a way to see the whole
943 extended description.
947 The description should also give information about the
948 significant dependencies and conflicts between this package
949 and others, so that the user knows why these dependencies and
950 conflicts have been declared.
954 Instructions for configuring or using the package should
955 not be included (that is what installation scripts,
956 manual pages, info files, etc., are for). Copyright
957 statements and other administrivia should not be included
958 either (that is what the copyright file is for).
961 <sect1 id="synopsis"><heading>The single line synopsis</heading>
964 The single line synopsis should be kept brief - certainly
969 Do not include the package name in the synopsis line. The
970 display software knows how to display this already, and you
971 do not need to state it. Remember that in many situations
972 the user may only see the synopsis line - make it as
973 informative as you can.
978 <sect1 id="extendeddesc"><heading>The extended description</heading>
981 Do not try to continue the single line synopsis into the
982 extended description. This will not work correctly when
983 the full description is displayed, and makes no sense
984 where only the summary (the single line synopsis) is
989 The extended description should describe what the package
990 does and how it relates to the rest of the system (in terms
991 of, for example, which subsystem it is which part of).
995 The description field needs to make sense to anyone, even
996 people who have no idea about any of the things the
997 package deals with.<footnote>
998 The blurb that comes with a program in its
999 announcements and/or <prgn>README</prgn> files is
1000 rarely suitable for use in a description. It is
1001 usually aimed at people who are already in the
1002 community where the package is used.
1011 <heading>Dependencies</heading>
1014 Every package must specify the dependency information
1015 about other packages that are required for the first to
1020 For example, a dependency entry must be provided for any
1021 shared libraries required by a dynamically-linked executable
1022 binary in a package.
1026 Packages are not required to declare any dependencies they
1027 have on other packages which are marked <tt>Essential</tt>
1028 (see below), and should not do so unless they depend on a
1029 particular version of that package.
1033 Sometimes, a package requires another package to be installed
1034 <em>and</em> configured before it can be installed. In this
1035 case, you must specify a <tt>Pre-Depends</tt> entry for
1040 You should not specify a <tt>Pre-Depends</tt> entry for a
1041 package before this has been discussed on the
1042 <tt>debian-devel</tt> mailing list and a consensus about
1043 doing that has been reached.
1047 The format of the package interrelationship control fields is
1048 described in <ref id="relationships">.
1052 <sect id="virtual_pkg">
1053 <heading>Virtual packages</heading>
1056 Sometimes, there are several packages which offer
1057 more-or-less the same functionality. In this case, it's
1058 useful to define a <em>virtual package</em> whose name
1059 describes that common functionality. (The virtual
1060 packages only exist logically, not physically; that's why
1061 they are called <em>virtual</em>.) The packages with this
1062 particular function will then <em>provide</em> the virtual
1063 package. Thus, any other package requiring that function
1064 can simply depend on the virtual package without having to
1065 specify all possible packages individually.
1069 All packages should use virtual package names where
1070 appropriate, and arrange to create new ones if necessary.
1071 They should not use virtual package names (except privately,
1072 amongst a cooperating group of packages) unless they have
1073 been agreed upon and appear in the list of virtual package
1074 names. (See also <ref id="virtual">)
1078 The latest version of the authoritative list of virtual
1079 package names can be found in the <tt>debian-policy</tt> package.
1080 It is also available from the Debian web mirrors at
1081 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1082 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
1083 and from the Debian archive mirrors at
1084 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
1085 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
1089 The procedure for updating the list is described in the preface
1096 <heading>Base system</heading>
1099 The <tt>base system</tt> is a minimum subset of the Debian
1100 GNU/Linux system that is installed before everything else
1101 on a new system. Thus, only very few packages are allowed
1102 to go into the <tt>base</tt> section to keep the required
1103 disk usage very small.
1107 Most of these packages will have the priority value
1108 <tt>required</tt> or at least <tt>important</tt>, and many
1109 of them will be tagged <tt>essential</tt> (see below).
1114 <heading>Essential packages</heading>
1117 Some packages are tagged <tt>essential</tt> for a system
1118 using the <tt>Essential</tt> control file field.
1119 The format of the <tt>Essential</tt> control field is
1120 described in <ref id="f-Essential">.
1124 Since these packages cannot be easily removed (one has to
1125 specify an extra <em>force option</em> to
1126 <prgn>dpkg</prgn> to do so), this flag must not be used
1127 unless absolutely necessary. A shared library package
1128 must not be tagged <tt>essential</tt>; dependencies will
1129 prevent its premature removal, and we need to be able to
1130 remove it when it has been superseded.
1134 Since dpkg will not prevent upgrading of other packages
1135 while an <tt>essential</tt> package is in an unconfigured
1136 state, all <tt>essential</tt> packages must supply all of
1137 their core functionality even when unconfigured. If the
1138 package cannot satisfy this requirement it must not be
1139 tagged as essential, and any packages depending on this
1140 package must instead have explicit dependency fields as
1145 You must not tag any packages <tt>essential</tt> before
1146 this has been discussed on the <tt>debian-devel</tt>
1147 mailing list and a consensus about doing that has been
1153 <heading>Tasks</heading>
1156 The Debian install process allows the user to choose from
1157 a number of common tasks which a Debian system can be used to
1158 perform. Selecting a task with <prgn>tasksel</prgn> causes
1159 a set of packages that are useful in performing that task to be
1164 This set of packages is all available packages which have the
1165 name of the selected task in the <tt>Task</tt> field of their
1166 control file. The format of this field is a list of tasks,
1167 separated by commas.
1171 You should not tag any packages as belonging to a task
1172 before this has been discussed on the
1173 <em>debian-devel</em> mailing list and a consensus about
1174 doing that has been reached.
1178 For third parties (and historical reasons), tasksel also
1179 supports constructing tasks based on <em>task
1180 packages</em>. These are packages whose names begin with
1181 <em>task-</em>. Task packages should not be included in the
1186 <sect id="maintscripts">
1187 <heading>Maintainer Scripts</heading>
1190 The package installation scripts should avoid producing
1191 output which it is unnecessary for the user to see and
1192 should rely on <prgn>dpkg</prgn> to stave off boredom on
1193 the part of a user installing many packages. This means,
1194 amongst other things, using the <tt>--quiet</tt> option on
1195 <prgn>install-info</prgn>.
1199 Errors which occur during the execution of an installation
1200 script must be checked and the installation must not
1201 continue after an error.
1205 Note that in general <ref id="scripts"> applies to package
1206 maintainer scripts, too.
1210 You should not use <prgn>dpkg-divert</prgn> on a file
1211 belonging to another package without consulting the
1212 maintainer of that package first.
1216 All packages which supply an instance of a common command
1217 name (or, in general, filename) should generally use
1218 <prgn>update-alternatives</prgn>, so that they may be
1219 installed together. If <prgn>update-alternatives</prgn>
1220 is not used, then each package must use
1221 <tt>Conflicts</tt> to ensure that other packages are
1222 de-installed. (In this case, it may be appropriate to
1223 specify a conflict against earlier versions of something
1224 that previously did not use
1225 <prgn>update-alternatives</prgn>; this is an exception to
1226 the usual rule that versioned conflicts should be
1230 <sect1 id="maintscriptprompt">
1231 <heading>Prompting in maintainer scripts</heading>
1233 Package maintainer scripts may prompt the user if
1234 necessary. Prompting should be done by communicating
1235 through a program, such as <prgn>debconf</prgn>, which
1236 conforms to the Debian Configuration management
1237 specification, version 2 or higher. Prompting the user by
1238 other means, such as by hand<footnote>
1239 From the Jargon file: by hand 2. By extension,
1240 writing code which does something in an explicit or
1241 low-level way for which a presupplied library
1242 (<em>debconf, in this instance</em>) routine ought
1243 to have been available.
1244 </footnote>, is now deprecated.
1248 The Debian Configuration management specification is included
1249 in the <file>debconf_specification</file> files in the
1250 <package>debian-policy</package> package.
1251 It is also available from the Debian web mirrors at
1252 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1253 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1254 and from the Debian archive mirrors at
1255 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1256 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1260 Packages which use the Debian Configuration management
1261 specification may contain an additional
1262 <prgn>config</prgn> script and a <tt>templates</tt>
1263 file in their control archive<footnote>
1264 The control.tar.gz inside the .deb.
1265 See <manref name="deb" section="5">.
1267 The <prgn>config</prgn> script might be run before the
1268 <prgn>preinst</prgn> script, and before the package is unpacked
1269 or any of its dependencies or pre-dependancies are satisfied.
1270 Therefore it must work using only the tools present in
1271 <em>essential</em> packages.<footnote>
1272 <package>Debconf</package> or another tool that
1273 implements the Debian Configuration management
1274 specification will also be installed, and any
1275 versioned dependencies on it will be satisfied
1276 before preconfiguration begins.
1281 Packages should try to minimize the amount of prompting
1282 they need to do, and they should ensure that the user
1283 will only ever be asked each question once. This means
1284 that packages should try to use appropriate shared
1285 configuration files (such as <file>/etc/papersize</file> and
1286 <file>/etc/news/server</file>), and shared
1287 <package>debconf</package> variables rather than each
1288 prompting for their own list of required pieces of
1293 It also means that an upgrade should not ask the same
1294 questions again, unless the user has used
1295 <tt>dpkg --purge</tt> to remove the package's configuration.
1296 The answers to configuration questions should be stored in an
1297 appropriate place in <file>/etc</file> so that the user can
1298 modify them, and how this has been done should be
1303 If a package has a vitally important piece of
1304 information to pass to the user (such as "don't run me
1305 as I am, you must edit the following configuration files
1306 first or you risk your system emitting badly-formatted
1307 messages"), it should display this in the
1308 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1309 prompt the user to hit return to acknowledge the
1310 message. Copyright messages do not count as vitally
1311 important (they belong in
1312 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1313 neither do instructions on how to use a program (these
1314 should be in on-line documentation, where all the users
1319 Any necessary prompting should almost always be confined
1320 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1321 script. If it is done in the <prgn>postinst</prgn>, it
1322 should be protected with a conditional so that
1323 unnecessary prompting doesn't happen if a package's
1324 installation fails and the <prgn>postinst</prgn> is
1325 called with <tt>abort-upgrade</tt>,
1326 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1336 <heading>Source packages</heading>
1338 <sect id="standardsversion">
1339 <heading>Standards conformance</heading>
1342 Source packages should specify the most recent version number
1343 of this policy document with which your package complied
1344 when it was last updated.
1348 This information may be used to file bug reports
1349 automatically if your package becomes too much out of date.
1353 The version is specified in the <tt>Standards-Version</tt>
1355 The format of the <tt>Standards-Version</tt> field is
1356 described in <ref id="f-Standards-Version">.
1360 You should regularly, and especially if your package has
1361 become out of date, check for the newest Policy Manual
1362 available and update your package, if necessary. When your
1363 package complies with the new standards you should update the
1364 <tt>Standards-Version</tt> source package field and
1365 release it.<footnote>
1366 See the file <file>upgrading-checklist</file> for
1367 information about policy which has changed between
1368 different versions of this document.
1374 <sect id="pkg-relations">
1375 <heading>Package relationships</heading>
1378 Source packages should specify which binary packages they
1379 require to be installed or not to be installed in order to
1380 build correctly. For example, if building a package
1381 requires a certain compiler, then the compiler should be
1382 specified as a build-time dependency.
1386 It is not necessary to explicitly specify build-time
1387 relationships on a minimal set of packages that are always
1388 needed to compile, link and put in a Debian package a
1389 standard "Hello World!" program written in C or C++. The
1390 required packages are called <em>build-essential</em>, and
1391 an informational list can be found in
1392 <file>/usr/share/doc/build-essential/list</file> (which is
1393 contained in the <tt>build-essential</tt>
1396 <list compact="compact">
1398 This allows maintaining the list separately
1399 from the policy documents (the list does not
1400 need the kind of control that the policy
1404 Having a separate package allows one to install
1405 the build-essential packages on a machine, as
1406 well as allowing other packages such as tasks to
1407 require installation of the build-essential
1408 packages using the depends relation.
1411 The separate package allows bug reports against
1412 the list to be categorized separately from
1413 the policy management process in the BTS.
1420 When specifying the set of build-time dependencies, one
1421 should list only those packages explicitly required by the
1422 build. It is not necessary to list packages which are
1423 required merely because some other package in the list of
1424 build-time dependencies depends on them.<footnote>
1425 The reason for this is that dependencies change, and
1426 you should list all those packages, and <em>only</em>
1427 those packages that <em>you</em> need directly. What
1428 others need is their business. For example, if you
1429 only link against <file>libimlib</file>, you will need to
1430 build-depend on <package>libimlib2-dev</package> but
1431 not against any <tt>libjpeg*</tt> packages, even
1432 though <tt>libimlib2-dev</tt> currently depends on
1433 them: installation of <package>libimlib2-dev</package>
1434 will automatically ensure that all of its run-time
1435 dependencies are satisfied.
1440 If build-time dependencies are specified, it must be
1441 possible to build the package and produce working binaries
1442 on a system with only essential and build-essential
1443 packages installed and also those required to satisfy the
1444 build-time relationships (including any implied
1445 relationships). In particular, this means that version
1446 clauses should be used rigorously in build-time
1447 relationships so that one cannot produce bad or
1448 inconsistently configured packages when the relationships
1449 are properly satisfied.
1453 <ref id="relationships"> explains the technical details.
1458 <heading>Changes to the upstream sources</heading>
1461 If changes to the source code are made that are not
1462 specific to the needs of the Debian system, they should be
1463 sent to the upstream authors in whatever form they prefer
1464 so as to be included in the upstream version of the
1469 If you need to configure the package differently for
1470 Debian or for Linux, and the upstream source doesn't
1471 provide a way to do so, you should add such configuration
1472 facilities (for example, a new <prgn>autoconf</prgn> test
1473 or <tt>#define</tt>) and send the patch to the upstream
1474 authors, with the default set to the way they originally
1475 had it. You can then easily override the default in your
1476 <file>debian/rules</file> or wherever is appropriate.
1480 You should make sure that the <prgn>configure</prgn> utility
1481 detects the correct architecture specification string
1482 (refer to <ref id="arch-spec"> for details).
1486 If you need to edit a <prgn>Makefile</prgn> where
1487 GNU-style <prgn>configure</prgn> scripts are used, you
1488 should edit the <file>.in</file> files rather than editing the
1489 <prgn>Makefile</prgn> directly. This allows the user to
1490 reconfigure the package if necessary. You should
1491 <em>not</em> configure the package and edit the generated
1492 <prgn>Makefile</prgn>! This makes it impossible for
1493 someone else to later reconfigure the package.
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>. 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 Mistakes in changelogs are usually best rectified by making
1519 a new changelog entry rather than "rewriting history" by
1520 editing old changelog entries.
1524 The format of the <file>debian/changelog</file> allows the
1525 package building tools to discover which version of the package
1526 is being built and find out other release-specific information.
1530 That format is a series of entries like this:
1532 <example compact="compact">
1533 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1535 [optional blank line(s), stripped]
1537 * <var>change details</var>
1538 <var>more change details</var>
1540 [blank line(s), included in output of dpkg-parsechangelog]
1542 * <var>even more change details</var>
1544 [optional blank line(s), stripped]
1546 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1551 <var>package</var> and <var>version</var> are the source
1552 package name and version number.
1556 <var>distribution(s)</var> lists the distributions where
1557 this version should be installed when it is uploaded - it
1558 is copied to the <tt>Distribution</tt> field in the
1559 <file>.changes</file> file. See <ref id="f-Distribution">.
1563 <var>urgency</var> is the value for the <tt>Urgency</tt>
1564 field in the <file>.changes</file> file for the upload
1565 (see <ref id="f-Urgency">). It is not possible to specify
1566 an urgency containing commas; commas are used to separate
1567 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1568 <prgn>dpkg</prgn> changelog format (though there is
1569 currently only one useful <var>keyword</var>,
1570 <tt>urgency</tt>).<footnote>
1571 Recognised urgency values are <tt>low</tt>,
1572 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1573 They have an effect on how quickly a package will be
1574 considered for inclusion into the <tt>testing</tt>
1575 distribution, and give an indication of the importance
1576 of any fixes included in this upload.
1581 The change details may in fact be any series of lines
1582 starting with at least two spaces, but conventionally each
1583 change starts with an asterisk and a separating space and
1584 continuation lines are indented so as to bring them in
1585 line with the start of the text above. Blank lines may be
1586 used here to separate groups of changes, if desired.
1590 If this upload resolves bugs recorded in the Bug Tracking
1591 System (BTS), they may be automatically closed on the
1592 inclusion of this package into the Debian archive by
1593 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1594 in the change details.<footnote>
1595 To be precise, the string should match the following
1596 Perl regular expression:
1598 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1600 Then all of the bug numbers listed will be closed by the
1601 archive maintenance script (<prgn>katie</prgn>), or in
1602 the case of an NMU, marked as fixed.
1604 This information is conveyed via the <tt>Closes</tt> field
1605 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1609 The maintainer name and email address used in the changelog
1610 should be the details of the person uploading <em>this</em>
1611 version. They are <em>not</em> necessarily those of the
1612 usual package maintainer. The information here will be
1613 copied to the <tt>Changed-By</tt> field in the
1614 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1615 and then later used to send an acknowledgement when the
1616 upload has been installed.
1620 The <var>date</var> should be in RFC822 format<footnote>
1621 This is generated by the <prgn>822-date</prgn>
1623 </footnote>; it should include the time zone specified
1624 numerically, with the time zone name or abbreviation
1625 optionally present as a comment in parentheses.
1629 The first "title" line with the package name should start
1630 at the left hand margin; the "trailer" line with the
1631 maintainer and date details should be preceded by exactly
1632 one space. The maintainer details and the date must be
1633 separated by exactly two spaces.
1637 For more information on placement of the changelog files
1638 within binary packages, please see <ref id="changelogs">.
1641 <sect1><heading>Alternative changelog formats</heading>
1644 In non-experimental packages you must use a format for
1645 <file>debian/changelog</file> which is supported by the most
1646 recent released version of <prgn>dpkg</prgn>.
1650 It is possible to use a format different from the standard
1651 one by providing a changelog parser for the format you wish
1652 to use. The parser must have an API compatible with that
1653 expected by <prgn>dpkg-genchanges</prgn> and
1654 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1657 If there is general interest in the new format, you should
1658 contact the <package>dpkg</package> maintainer to have the
1659 parser script for it included in the <prgn>dpkg</prgn>
1660 package. (You will need to agree that the parser and its
1661 manpage may be distributed under the GNU GPL, just as the rest
1662 of <prgn>dpkg</prgn> is.)
1669 <heading>Error trapping in makefiles</heading>
1672 When <prgn>make</prgn> invokes a command in a makefile
1673 (including your package's upstream makefiles and
1674 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1675 means that <prgn>sh</prgn>'s usual bad error handling
1676 properties apply: if you include a miniature script as one
1677 of the commands in your makefile you'll find that if you
1678 don't do anything about it then errors are not detected
1679 and <prgn>make</prgn> will blithely continue after
1684 Every time you put more than one shell command (this
1685 includes using a loop) in a makefile command you
1686 must make sure that errors are trapped. For
1687 simple compound commands, such as changing directory and
1688 then running a program, using <tt>&&</tt> rather
1689 than semicolon as a command separator is sufficient. For
1690 more complex commands including most loops and
1691 conditionals you should include a separate <tt>set -e</tt>
1692 command at the start of every makefile command that's
1693 actually one of these miniature shell scripts.
1697 <sect id="timestamps">
1698 <heading>Time Stamps</heading>
1700 Maintainers should preserve the modification times of the
1701 upstream source files in a package, as far as is reasonably
1703 The rationale is that there is some information conveyed
1704 by knowing the age of the file, for example, you could
1705 recognize that some documentation is very old by looking
1706 at the modification time, so it would be nice if the
1707 modification time of the upstream source would be
1713 <sect id="restrictions">
1714 <heading>Restrictions on objects in source packages</heading>
1717 The source package may not contain any hard links<footnote>
1719 This is not currently detected when building source
1720 packages, but only when extracting
1724 Hard links may be permitted at some point in the
1725 future, but would require a fair amount of
1728 </footnote>, device special files, sockets or setuid or
1729 setgid files.<footnote>
1730 Setgid directories are allowed.
1735 <sect id="debianrules">
1736 <heading>Main building script: <file>debian/rules</file></heading>
1739 This file must be an executable makefile, and contains the
1740 package-specific recipes for compiling the package and
1741 building binary package(s) from the source.
1745 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1746 so that it can be invoked by saying its name rather than
1747 invoking <prgn>make</prgn> explicitly.
1751 Since an interactive <file>debian/rules</file> script makes it
1752 impossible to auto-compile that package and also makes it
1753 hard for other people to reproduce the same binary
1754 package, all <em>required targets</em> MUST be
1755 non-interactive. At a minimum, required targets are the
1756 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1757 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1758 <em>binary-indep</em>, and <em>build</em>. It also follows
1759 that any target that these targets depend on must also be
1764 The targets are as follows (required unless stated otherwise):
1766 <tag><tt>build</tt></tag>
1769 The <tt>build</tt> target should perform all the
1770 configuration and compilation of the package.
1771 If a package has an interactive pre-build
1772 configuration routine, the Debianized source package
1773 must either be built after this has taken place (so
1774 that the binary package can be built without rerunning
1775 the configuration) or the configuration routine
1776 modified to become non-interactive. (The latter is
1777 preferable if there are architecture-specific features
1778 detected by the configuration routine.)
1782 For some packages, notably ones where the same
1783 source tree is compiled in different ways to produce
1784 two binary packages, the <tt>build</tt> target
1785 does not make much sense. For these packages it is
1786 good enough to provide two (or more) targets
1787 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1788 for each of the ways of building the package, and a
1789 <tt>build</tt> target that does nothing. The
1790 <tt>binary</tt> target will have to build the
1791 package in each of the possible ways and make the
1792 binary package out of each.
1796 The <tt>build</tt> target must not do anything
1797 that might require root privilege.
1801 The <tt>build</tt> target may need to run the
1802 <tt>clean</tt> target first - see below.
1806 When a package has a configuration and build routine
1807 which takes a long time, or when the makefiles are
1808 poorly designed, or when <tt>build</tt> needs to
1809 run <tt>clean</tt> first, it is a good idea to
1810 <tt>touch build</tt> when the build process is
1811 complete. This will ensure that if <tt>debian/rules
1812 build</tt> is run again it will not rebuild the whole
1814 Another common way to do this is for <tt>build</tt>
1815 to depend on <prgn>build-stamp</prgn> and to do
1816 nothing else, and for the <prgn>build-stamp</prgn>
1817 target to do the building and to <tt>touch
1818 build-stamp</tt> on completion. This is
1819 especially useful if the build routine creates a
1820 file or directory called <tt>build</tt>; in such a
1821 case, <tt>build</tt> will need to be listed as
1822 a phony target (i.e., as a dependency of the
1823 <tt>.PHONY</tt> target). See the documentation of
1824 <prgn>make</prgn> for more information on phony
1830 <tag><tt>build-arch</tt> (optional),
1831 <tt>build-indep</tt> (optional)
1835 A package may also provide both of the targets
1836 <tt>build-arch</tt> and <tt>build-indep</tt>.
1837 The <tt>build-arch</tt> target, if provided, should
1838 perform all the configuration and compilation required
1839 for producing all architecture-dependant binary packages
1840 (those packages for which the body of the
1841 <tt>Architecture</tt> field in <tt>debian/control</tt>
1842 is not <tt>all</tt>).
1843 Similarly, the <tt>build-indep</tt> target, if
1844 provided, should perform all the configuration and
1845 compilation required for producing all
1846 architecture-independent binary packages
1847 (those packages for which the body of the
1848 <tt>Architecture</tt> field in <tt>debian/control</tt>
1850 The <tt>build</tt> target should depend on those of the
1851 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1852 are provided in the rules file.
1856 If one or both of the targets <tt>build-arch</tt> and
1857 <tt>build-indep</tt> are not provided, then invoking
1858 <file>debian/rules</file> with one of the not-provided
1859 targets as arguments should produce a exit status code
1860 of 2. Usually this is provided automatically by make
1861 if the target is missing.
1865 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1866 must not do anything that might require root privilege.
1870 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1871 <tt>binary-indep</tt>
1875 The <tt>binary</tt> target must be all that is
1876 necessary for the user to build the binary package(s)
1877 produced from this source package. It is
1878 split into two parts: <prgn>binary-arch</prgn> builds
1879 the binary packages which are specific to a particular
1880 architecture, and <tt>binary-indep</tt> builds
1881 those which are not.
1884 <tt>binary</tt> may be (and commonly is) a target with
1885 no commands which simply depends on
1886 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1889 Both <tt>binary-*</tt> targets should depend on the
1890 <tt>build</tt> target, or on the appropriate
1891 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1892 provided, so that the package is built if it has not
1893 been already. It should then create the relevant
1894 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1895 make their control files and <prgn>dpkg-deb</prgn> to
1896 build them and place them in the parent of the top
1901 Both the <tt>binary-arch</tt> and
1902 <tt>binary-indep</tt> targets <em>must</em> exist.
1903 If one of them has nothing to do (which will always be
1904 the case if the source generates only a single binary
1905 package, whether architecture-dependent or not), it
1906 must still exist and must always succeed.
1910 The <tt>binary</tt> targets must be invoked as
1912 The <prgn>fakeroot</prgn> package often allows one
1913 to build a package correctly even without being
1919 <tag><tt>clean</tt></tag>
1922 This must undo any effects that the <tt>build</tt>
1923 and <tt>binary</tt> targets may have had, except
1924 that it should leave alone any output files created in
1925 the parent directory by a run of a <tt>binary</tt>
1930 If a <tt>build</tt> file is touched at the end of
1931 the <tt>build</tt> target, as suggested above, it
1932 should be removed as the first action that
1933 <tt>clean</tt> performs, so that running
1934 <tt>build</tt> again after an interrupted
1935 <tt>clean</tt> doesn't think that everything is
1940 The <tt>clean</tt> target may need to be
1941 invoked as root if <tt>binary</tt> has been
1942 invoked since the last <tt>clean</tt>, or if
1943 <tt>build</tt> has been invoked as root (since
1944 <tt>build</tt> may create directories, for
1949 <tag><tt>get-orig-source</tt> (optional)</tag>
1952 This target fetches the most recent version of the
1953 original source package from a canonical archive site
1954 (via FTP or WWW, for example), does any necessary
1955 rearrangement to turn it into the original source
1956 tar file format described below, and leaves it in the
1961 This target may be invoked in any directory, and
1962 should take care to clean up any temporary files it
1967 This target is optional, but providing it if
1968 possible is a good idea.
1974 The <tt>build</tt>, <tt>binary</tt> and
1975 <tt>clean</tt> targets must be invoked with the current
1976 directory being the package's top-level directory.
1981 Additional targets may exist in <file>debian/rules</file>,
1982 either as published or undocumented interfaces or for the
1983 package's internal use.
1987 The architectures we build on and build for are determined
1988 by <prgn>make</prgn> variables using the utility
1989 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1990 You can determine the
1991 Debian architecture and the GNU style architecture
1992 specification string for the build machine (the machine type
1993 we are building on) as well as for the host machine (the
1994 machine type we are building for). Here is a list of
1995 supported <prgn>make</prgn> variables:
1996 <list compact="compact">
1998 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2001 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2002 specification string)
2005 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2006 <tt>DEB_*_GNU_TYPE</tt>)
2009 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2010 <tt>DEB_*_GNU_TYPE</tt>)
2012 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2013 the build machine or <tt>HOST</tt> for specification of the
2018 Backward compatibility can be provided in the rules file
2019 by setting the needed variables to suitable default
2020 values; please refer to the documentation of
2021 <prgn>dpkg-architecture</prgn> for details.
2025 It is important to understand that the <tt>DEB_*_ARCH</tt>
2026 string only determines which Debian architecture we are
2027 building on or for. It should not be used to get the CPU
2028 or system information; the GNU style variables should be
2033 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2034 <sect id="substvars">
2035 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2038 When <prgn>dpkg-gencontrol</prgn>,
2039 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2040 generate control files they perform variable substitutions
2041 on their output just before writing it. Variable
2042 substitutions have the form <tt>${<var>variable</var>}</tt>.
2043 The optional file <file>debian/substvars</file> contains
2044 variable substitutions to be used; variables can also be set
2045 directly from <file>debian/rules</file> using the <tt>-V</tt>
2046 option to the source packaging commands, and certain
2047 predefined variables are also available.
2051 The <file>debian/substvars</file> file is usually generated and
2052 modified dynamically by <file>debian/rules</file> targets, in
2053 which case it must be removed by the <tt>clean</tt> target.
2057 See <manref name="dpkg-source" section="1"> for full
2058 details about source variable substitutions, including the
2059 format of <file>debian/substvars</file>.</p>
2062 <sect id="debianfiles">
2063 <heading>Generated files list: <file>debian/files</file></heading>
2066 This file is not a permanent part of the source tree; it
2067 is used while building packages to record which files are
2068 being generated. <prgn>dpkg-genchanges</prgn> uses it
2069 when it generates a <file>.changes</file> file.
2073 It should not exist in a shipped source package, and so it
2074 (and any backup files or temporary files such as
2075 <file>files.new</file><footnote>
2076 <file>files.new</file> is used as a temporary file by
2077 <prgn>dpkg-gencontrol</prgn> and
2078 <prgn>dpkg-distaddfile</prgn> - they write a new
2079 version of <tt>files</tt> here before renaming it,
2080 to avoid leaving a corrupted copy if an error
2082 </footnote>) should be removed by the
2083 <tt>clean</tt> target. It may also be wise to
2084 ensure a fresh start by emptying or removing it at the
2085 start of the <tt>binary</tt> target.
2089 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2090 package, it adds an entry to <file>debian/files</file> for the
2091 <file>.deb</file> file that will be created when <tt>dpkg-deb
2092 --build</tt> is run for that binary package. So for most
2093 packages all that needs to be done with this file is to
2094 delete it in the <tt>clean</tt> target.
2098 If a package upload includes files besides the source
2099 package and any binary packages whose control files were
2100 made with <prgn>dpkg-gencontrol</prgn> then they should be
2101 placed in the parent of the package's top-level directory
2102 and <prgn>dpkg-distaddfile</prgn> should be called to add
2103 the file to the list in <file>debian/files</file>.</p>
2109 <chapt id="controlfields">
2110 <heading>Control files and their fields</heading>
2113 The package management system manipulates data represented in
2114 a common format, known as <em>control data</em>, stored in
2115 <em>control files</em>.
2116 Control files are used for source packages, binary packages and
2117 the <file>.changes</file> files which control the installation
2118 of uploaded files<footnote>
2119 <prgn>dpkg</prgn>'s internal databases are in a similar
2124 <sect id="controlsyntax">
2125 <heading>Syntax of control files</heading>
2128 A control file consists of one or more paragraphs of
2130 The paragraphs are also sometimes referred to as stanzas.
2132 The paragraphs are separated by blank lines. Some control
2133 files allow only one paragraph; others allow several, in
2134 which case each paragraph usually refers to a different
2135 package. (For example, in source packages, the first
2136 paragraph refers to the source package, and later paragraphs
2137 refer to binary packages generated from the source.)
2141 Each paragraph consists of a series of data fields; each
2142 field consists of the field name, followed by a colon and
2143 then the data/value associated with that field. It ends at
2144 the end of the line. Horizontal whitespace (spaces and
2145 tabs) may occur immediately before or after the value and is
2146 ignored there; it is conventional to put a single space
2147 after the colon. For example, a field might be:
2148 <example compact="compact">
2151 the field name is <tt>Package</tt> and the field value
2156 Some fields' values may span several lines; in this case
2157 each continuation line must start with a space or a tab.
2158 Any trailing spaces or tabs at the end of individual
2159 lines of a field value are ignored.
2163 Except where otherwise stated, only a single line of data is
2164 allowed and whitespace is not significant in a field body.
2165 Whitespace must not appear inside names (of packages,
2166 architectures, files or anything else) or version numbers,
2167 or between the characters of multi-character version
2172 Field names are not case-sensitive, but it is usual to
2173 capitalize the field names using mixed case as shown below.
2177 Blank lines, or lines consisting only of spaces and tabs,
2178 are not allowed within field values or between fields - that
2179 would mean a new paragraph.
2184 <sect id="sourcecontrolfiles">
2185 <heading>Source package control files -- <file>debian/control</file></heading>
2188 The <file>debian/control</file> file contains the most vital
2189 (and version-independent) information about the source package
2190 and about the binary packages it creates.
2194 The first paragraph of the control file contains information about
2195 the source package in general. The subsequent sets each describe a
2196 binary package that the source tree builds.
2200 The fields in the general paragraph (the first one, for the source
2203 <list compact="compact">
2204 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2205 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2206 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2207 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2208 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2209 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2214 The fields in the binary package paragraphs are:
2216 <list compact="compact">
2217 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2218 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2219 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2220 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2221 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2222 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2223 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2228 The syntax and semantics of the fields are described below.
2234 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2235 generate control files for binary packages (see below), by
2236 <prgn>dpkg-genchanges</prgn> to generate the
2237 <tt>.changes</tt> file to accompany the upload, and by
2238 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2239 source control file as part of a source archive.
2243 The fields here may contain variable references - their
2244 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2245 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2246 when they generate output control files.
2247 See <ref id="substvars"> for details.
2252 <sect id="binarycontrolfiles">
2253 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2256 The <file>DEBIAN/control</file> file contains the most vital
2257 (and version-dependent) information about a binary package.
2261 The fields in this file are:
2263 <list compact="compact">
2264 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2265 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2266 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2267 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2268 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2269 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2271 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2272 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2273 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2274 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2279 <sect id="debiansourcecontrolfiles">
2280 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2283 This file contains a series of fields, identified and
2284 separated just like the fields in the control file of
2285 a binary package. The fields are listed below; their
2286 syntax is described above, in <ref id="pkg-controlfields">.
2288 <list compact="compact">
2289 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2290 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2291 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2292 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2293 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2294 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2295 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2296 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2297 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2302 The source package control file is generated by
2303 <prgn>dpkg-source</prgn> when it builds the source
2304 archive, from other files in the source package,
2305 described above. When unpacking, it is checked against
2306 the files and directories in the other parts of the
2312 <sect id="debianchangesfiles">
2313 <heading>Debian changes files -- <file>.changes</file></heading>
2316 The .changes files are used by the Debian archive maintenance
2317 software to process updates to packages. They contain one
2318 paragraph which contains information from the
2319 <tt>debian/control</tt> file and other data about the
2320 source package gathered via <tt>debian/changelog</tt>
2321 and <tt>debian/rules</tt>.
2325 The fields in this file are:
2327 <list compact="compact">
2328 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2329 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2330 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2333 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2335 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2336 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2337 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2338 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2339 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2340 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2341 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2346 <sect id="controlfieldslist">
2347 <heading>List of fields</heading>
2349 <sect1 id="f-Source">
2350 <heading><tt>Source</tt></heading>
2353 This field identifies the source package name.
2357 In a main source control information, a <file>.changes</file>
2358 or a <file>.dsc</file> file this may contain only the name
2359 of the source package.
2363 In the control file of a binary package it may be followed
2364 by a version number in parentheses<footnote>
2365 It is customary to leave a space after the package name
2366 if a version number is specified.
2368 This version number may be omitted (and is, by
2369 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2370 the <tt>Version</tt> field of the binary package in
2371 question. The field itself may be omitted from a binary
2372 package control file when the source package has the same
2373 name and version as the binary package.
2377 <sect1 id="f-Maintainer">
2378 <heading><tt>Maintainer</tt></heading>
2381 The package maintainer's name and email address. The name
2382 should come first, then the email address inside angle
2383 brackets <tt><></tt> (in RFC822 format).
2387 If the maintainer's name contains a full stop then the
2388 whole field will not work directly as an email address due
2389 to a misfeature in the syntax specified in RFC822; a
2390 program using this field as an address must check for this
2391 and correct the problem if necessary (for example by
2392 putting the name in round brackets and moving it to the
2393 end, and bringing the email address forward).
2397 <sect1 id="f-Changed-By">
2398 <heading><tt>Changed-By</tt></heading>
2401 The name and email address of the person who changed the
2402 said package. Usually the name of the maintainer.
2403 All the rules for the Maintainer field apply here, too.
2407 <sect1 id="f-Section">
2408 <heading><tt>Section</tt></heading>
2411 This field specifies an application area into which the package
2412 has been classified. See <ref id="subsections">.
2416 When it appears in the <file>debian/control</file> file,
2417 it gives the value for the subfield of the same name in
2418 the <tt>Files</tt> field of the <file>.changes</file> file.
2419 It also gives the default for the same field in the binary
2424 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2425 field in the control file of a binary package - use the
2426 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2430 <sect1 id="f-Priority">
2431 <heading><tt>Priority</tt></heading>
2434 This field represents how important that it is that the user
2435 have the package installed. See <ref id="priorities">.
2439 When it appears in the <file>debian/control</file> file,
2440 it gives the value for the subfield of the same name in
2441 the <tt>Files</tt> field of the <file>.changes</file> file.
2442 It also gives the default for the same field in the binary
2447 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2448 field in the control file of a binary package - use the
2449 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2453 <sect1 id="f-Package">
2454 <heading><tt>Package</tt></heading>
2457 The name of the binary package.
2461 Package names must consist only of lower case letters
2462 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2463 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2464 They must be at least two characters long and must start
2465 with an alphanumeric character.
2469 <sect1 id="f-Architecture">
2470 <heading><tt>Architecture</tt></heading>
2473 Depending on context and the control file used, the
2474 <tt>Architecture</tt> field can include the following sets of
2477 <item>A unique single word identifying a Debian machine
2478 architecture, see <ref id="arch-spec">.
2479 <item><tt>all</tt>, which indicates an
2480 architecture-independent package.
2481 <item><tt>any</tt>, which indicates a package available
2482 for building on any architecture.
2483 <item><tt>source</tt>, which indicates a source package.
2488 In the main <file>debian/control</file> file in the source
2489 package, or in the source package control file
2490 <file>.dsc</file>, one may specify a list of architectures
2491 separated by spaces, or the special values <tt>any</tt> or
2496 Specifying <tt>any</tt> indicates that the source package
2497 isn't dependent on any particular architecture and should
2498 compile fine on any one. The produced binary package(s)
2499 will be specific to whatever the current build architecture
2501 This is the most often used setting, and is recommended
2502 for new packages that aren't <tt>Architecture: all</tt>.
2507 Specifying a list of architectures indicates that the source
2508 will build an architecture-dependent package, and will only
2509 work correctly on the listed architectures.<footnote>
2510 This is a setting used for a minority of cases where the
2511 program is not portable. Generally, it should not be used
2517 In a <file>.changes</file> file, the <tt>Architecture</tt>
2518 field lists the architecture(s) of the package(s)
2519 currently being uploaded. This will be a list; if the
2520 source for the package is also being uploaded, the special
2521 entry <tt>source</tt> is also present.
2525 See <ref id="debianrules"> for information how to get the
2526 architecture for the build process.
2530 <sect1 id="f-Essential">
2531 <heading><tt>Essential</tt></heading>
2534 This is a boolean field which may occur only in the
2535 control file of a binary package or in a per-package fields
2536 paragraph of a main source control data file.
2540 If set to <tt>yes</tt> then the package management system
2541 will refuse to remove the package (upgrading and replacing
2542 it is still possible). The other possible value is <tt>no</tt>,
2543 which is the same as not having the field at all.
2548 <heading>Package interrelationship fields:
2549 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2550 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2551 <tt>Provides</tt>, <tt>Replaces</tt>
2555 These fields describe the package's relationships with
2556 other packages. Their syntax and semantics are described
2557 in <ref id="relationships">.</p>
2560 <sect1 id="f-Standards-Version">
2561 <heading><tt>Standards-Version</tt></heading>
2564 The most recent version of the standards (the policy
2565 manual and associated texts) with which the package
2570 The version number has four components: major and minor
2571 version number and major and minor patch level. When the
2572 standards change in a way that requires every package to
2573 change the major number will be changed. Significant
2574 changes that will require work in many packages will be
2575 signaled by a change to the minor number. The major patch
2576 level will be changed for any change to the meaning of the
2577 standards, however small; the minor patch level will be
2578 changed when only cosmetic, typographical or other edits
2579 are made which neither change the meaning of the document
2580 nor affect the contents of packages.
2584 Thus only the first three components of the policy version
2585 are significant in the <em>Standards-Version</em> control
2586 field, and so either these three components or the all
2587 four components may be specified.<footnote>
2588 In the past, people specified the full version number
2589 in the Standards-Version field, for example "2.3.0.0".
2590 Since minor patch-level changes don't introduce new
2591 policy, it was thought it would be better to relax
2592 policy and only require the first 3 components to be
2593 specified, in this example "2.3.0". All four
2594 components may still be used if someone wishes to do so.
2600 <sect1 id="f-Version">
2601 <heading><tt>Version</tt></heading>
2604 The version number of a package. The format is:
2605 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2609 The three components here are:
2611 <tag><var>epoch</var></tag>
2614 This is a single (generally small) unsigned integer. It
2615 may be omitted, in which case zero is assumed. If it is
2616 omitted then the <var>upstream_version</var> may not
2621 It is provided to allow mistakes in the version numbers
2622 of older versions of a package, and also a package's
2623 previous version numbering schemes, to be left behind.
2627 <tag><var>upstream_version</var></tag>
2630 This is the main part of the version number. It is
2631 usually the version number of the original ("upstream")
2632 package from which the <file>.deb</file> file has been made,
2633 if this is applicable. Usually this will be in the same
2634 format as that specified by the upstream author(s);
2635 however, it may need to be reformatted to fit into the
2636 package management system's format and comparison
2641 The comparison behavior of the package management system
2642 with respect to the <var>upstream_version</var> is
2643 described below. The <var>upstream_version</var>
2644 portion of the version number is mandatory.
2648 The <var>upstream_version</var> may contain only
2649 alphanumerics<footnote>
2650 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2652 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2653 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2654 start with a digit. If there is no
2655 <var>debian_revision</var> then hyphens are not allowed;
2656 if there is no <var>epoch</var> then colons are not
2661 <tag><var>debian_revision</var></tag>
2664 This part of the version number specifies the version of
2665 the Debian package based on the upstream version. It
2666 may contain only alphanumerics and the characters
2667 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2668 compared in the same way as the
2669 <var>upstream_version</var> is.
2673 It is optional; if it isn't present then the
2674 <var>upstream_version</var> may not contain a hyphen.
2675 This format represents the case where a piece of
2676 software was written specifically to be turned into a
2677 Debian package, and so there is only one "debianization"
2678 of it and therefore no revision indication is required.
2682 It is conventional to restart the
2683 <var>debian_revision</var> at <tt>1</tt> each time the
2684 <var>upstream_version</var> is increased.
2688 The package management system will break the version
2689 number apart at the last hyphen in the string (if there
2690 is one) to determine the <var>upstream_version</var> and
2691 <var>debian_revision</var>. The absence of a
2692 <var>debian_revision</var> compares earlier than the
2693 presence of one (but note that the
2694 <var>debian_revision</var> is the least significant part
2695 of the version number).
2702 The <var>upstream_version</var> and <var>debian_revision</var>
2703 parts are compared by the package management system using the
2708 The strings are compared from left to right.
2712 First the initial part of each string consisting entirely of
2713 non-digit characters is determined. These two parts (one of
2714 which may be empty) are compared lexically. If a difference
2715 is found it is returned. The lexical comparison is a
2716 comparison of ASCII values modified so that all the letters
2717 sort earlier than all the non-letters.
2721 Then the initial part of the remainder of each string which
2722 consists entirely of digit characters is determined. The
2723 numerical values of these two parts are compared, and any
2724 difference found is returned as the result of the comparison.
2725 For these purposes an empty string (which can only occur at
2726 the end of one or both version strings being compared) counts
2731 These two steps (comparing and removing initial non-digit
2732 strings and initial digit strings) are repeated until a
2733 difference is found or both strings are exhausted.
2737 Note that the purpose of epochs is to allow us to leave behind
2738 mistakes in version numbering, and to cope with situations
2739 where the version numbering scheme changes. It is
2740 <em>not</em> intended to cope with version numbers containing
2741 strings of letters which the package management system cannot
2742 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2743 silly orderings (the author of this manual has heard of a
2744 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2745 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2746 <tt>2</tt> and so forth).
2750 <sect1 id="f-Description">
2751 <heading><tt>Description</tt></heading>
2754 In a source or binary control file, the <tt>Description</tt>
2755 field contains a description of the binary package, consisting
2756 of two parts, the synopsis or the short description, and the
2757 long description. The field's format is as follows:
2762 Description: <single line synopsis>
2763 <extended description over several lines>
2768 The lines in the extended description can have these formats:
2774 Those starting with a single space are part of a paragraph.
2775 Successive lines of this form will be word-wrapped when
2776 displayed. The leading space will usually be stripped off.
2780 Those starting with two or more spaces. These will be
2781 displayed verbatim. If the display cannot be panned
2782 horizontally, the displaying program will linewrap them "hard"
2783 (i.e., without taking account of word breaks). If it can they
2784 will be allowed to trail off to the right. None, one or two
2785 initial spaces may be deleted, but the number of spaces
2786 deleted from each line will be the same (so that you can have
2787 indenting work correctly, for example).
2791 Those containing a single space followed by a single full stop
2792 character. These are rendered as blank lines. This is the
2793 <em>only</em> way to get a blank line<footnote>
2794 Completely empty lines will not be rendered as blank lines.
2795 Instead, they will cause the parser to think you're starting
2796 a whole new record in the control file, and will therefore
2797 likely abort with an error.
2802 Those containing a space, a full stop and some more characters.
2803 These are for future expansion. Do not use them.
2809 Do not use tab characters. Their effect is not predictable.
2813 See <ref id="descriptions"> for further information on this.
2817 In a <file>.changes</file> file, the <tt>Description</tt> field
2818 contains a summary of the descriptions for the packages being
2823 The part of the field before the first newline is empty;
2824 thereafter each line has the name of a binary package and
2825 the summary description line from that binary package.
2826 Each line is indented by one space.
2831 <sect1 id="f-Distribution">
2832 <heading><tt>Distribution</tt></heading>
2835 In a <file>.changes</file> file or parsed changelog output
2836 this contains the (space-separated) name(s) of the
2837 distribution(s) where this version of the package should
2838 be installed. Valid distributions are determined by the
2839 archive maintainers.<footnote>
2840 Current distribution names are:
2841 <taglist compact="compact">
2842 <tag><em>stable</em></tag>
2844 This is the current "released" version of Debian
2845 GNU/Linux. Once the distribution is
2846 <em>stable</em> only security fixes and other
2847 major bug fixes are allowed. When changes are
2848 made to this distribution, the release number is
2849 increased (for example: 2.2r1 becomes 2.2r2 then
2853 <tag><em>unstable</em></tag>
2855 This distribution value refers to the
2856 <em>developmental</em> part of the Debian
2857 distribution tree. New packages, new upstream
2858 versions of packages and bug fixes go into the
2859 <em>unstable</em> directory tree. Download from
2860 this distribution at your own risk.
2863 <tag><em>testing</em></tag>
2865 This distribution value refers to the
2866 <em>testing</em> part of the Debian distribution
2867 tree. It receives its packages from the
2868 unstable distribution after a short time lag to
2869 ensure that there are no major issues with the
2870 unstable packages. It is less prone to breakage
2871 than unstable, but still risky. It is not
2872 possible to upload packages directly to
2876 <tag><em>frozen</em></tag>
2878 From time to time, the <em>testing</em>
2879 distribution enters a state of "code-freeze" in
2880 anticipation of release as a <em>stable</em>
2881 version. During this period of testing only
2882 fixes for existing or newly-discovered bugs will
2883 be allowed. The exact details of this stage are
2884 determined by the Release Manager.
2887 <tag><em>experimental</em></tag>
2889 The packages with this distribution value are
2890 deemed by their maintainers to be high
2891 risk. Oftentimes they represent early beta or
2892 developmental packages from various sources that
2893 the maintainers want people to try, but are not
2894 ready to be a part of the other parts of the
2895 Debian distribution tree. Download at your own
2901 You should list <em>all</em> distributions that the
2902 package should be installed into.
2906 More information is available in the Debian Developer's
2907 Reference, section "The Debian archive".
2914 <heading><tt>Date</tt></heading>
2917 This field includes the date the package was built or last edited.
2921 The value of this field is usually extracted from the
2922 <file>debian/changelog</file> file - see
2923 <ref id="dpkgchangelog">).
2927 <sect1 id="f-Format">
2928 <heading><tt>Format</tt></heading>
2931 This field specifies a format revision for the file.
2932 The most current format described in the Policy Manual
2933 is version <strong>1.5</strong>. The syntax of the
2934 format value is the same as that of a package version
2935 number except that no epoch or Debian revision is allowed
2936 - see <ref id="f-Version">.
2940 <sect1 id="f-Urgency">
2941 <heading><tt>Urgency</tt></heading>
2944 This is a description of how important it is to upgrade to
2945 this version from previous ones. It consists of a single
2946 keyword usually taking one of the values <tt>low</tt>,
2947 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2948 followed by an optional commentary (separated by a space)
2949 which is usually in parentheses. For example:
2952 Urgency: low (HIGH for users of diversions)
2958 The value of this field is usually extracted from the
2959 <file>debian/changelog</file> file - see
2960 <ref id="dpkgchangelog">.
2964 <sect1 id="f-Changes">
2965 <heading><tt>Changes</tt></heading>
2968 This field contains the human-readable changes data, describing
2969 the differences between the last version and the current one.
2973 There should be nothing in this field before the first
2974 newline; all the subsequent lines must be indented by at
2975 least one space; blank lines must be represented by a line
2976 consiting only of a space and a full stop.
2980 The value of this field is usually extracted from the
2981 <file>debian/changelog</file> file - see
2982 <ref id="dpkgchangelog">).
2986 Each version's change information should be preceded by a
2987 "title" line giving at least the version, distribution(s)
2988 and urgency, in a human-readable way.
2992 If data from several versions is being returned the entry
2993 for the most recent version should be returned first, and
2994 entries should be separated by the representation of a
2995 blank line (the "title" line may also be followed by the
2996 representation of blank line).
3000 <sect1 id="f-Binary">
3001 <heading><tt>Binary</tt></heading>
3004 This field is a list of binary packages.
3008 When it appears in the <file>.dsc</file> file it is the list
3009 of binary packages which a source package can produce. It
3010 does not necessarily produce all of these binary packages
3011 for every architecture. The source control file doesn't
3012 contain details of which architectures are appropriate for
3013 which of the binary packages.
3017 When it appears in a <file>.changes</file> file it lists the
3018 names of the binary packages actually being uploaded.
3022 The syntax is a list of binary packages separated by
3024 A space after each comma is conventional.
3025 </footnote>. Currently the packages must be separated using
3026 only spaces in the <file>.changes</file> file.
3030 <sect1 id="f-Installed-Size">
3031 <heading><tt>Installed-Size</tt></heading>
3034 This field appears in the control files of binary
3035 packages, and in the <file>Packages</file> files. It gives
3036 the total amount of disk space required to install the
3041 The disk space is represented in kilobytes as a simple
3046 <sect1 id="f-Files">
3047 <heading><tt>Files</tt></heading>
3050 This field contains a list of files with information about
3051 each one. The exact information and syntax varies with
3052 the context. In all cases the part of the field
3053 contents on the same line as the field name is empty. The
3054 remainder of the field is one line per file, each line
3055 being indented by one space and containing a number of
3056 sub-fields separated by spaces.
3060 In the <file>.dsc</file> file, each line contains the MD5
3061 checksum, size and filename of the tar file and (if applicable)
3062 diff file which make up the remainder of the source
3064 That is, the parts which are not the <tt>.dsc</tt>.
3066 The exact forms of the filenames are described
3067 in <ref id="pkg-sourcearchives">.
3071 In the <file>.changes</file> file this contains one line per
3072 file being uploaded. Each line contains the MD5 checksum,
3073 size, section and priority and the filename.
3074 The <qref id="f-Section">section</qref>
3075 and <qref id="f-Priority">priority</qref>
3076 are the values of the corresponding fields in
3077 the main source control file. If no section or priority is
3078 specified then <tt>-</tt> should be used, though section
3079 and priority values must be specified for new packages to
3080 be installed properly.
3084 The special value <tt>byhand</tt> for the section in a
3085 <tt>.changes</tt> file indicates that the file in question
3086 is not an ordinary package file and must by installed by
3087 hand by the distribution maintainers. If the section is
3088 <tt>byhand</tt> the priority should be <tt>-</tt>.
3092 If a new Debian revision of a package is being shipped and
3093 no new original source archive is being distributed the
3094 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3095 entry for the original source archive
3096 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3097 but the <file>.changes</file> file should leave it out. In
3098 this case the original source archive on the distribution
3099 site must match exactly, byte-for-byte, the original
3100 source archive which was used to generate the
3101 <file>.dsc</file> file and diff which are being uploaded.</p>
3104 <sect1 id="f-Closes">
3105 <heading><tt>Closes</tt></heading>
3108 A space-separated list of bug report numbers that the upload
3109 governed by the .changes file closes.
3116 <heading>User-defined fields</heading>
3119 Additional user-defined fields may be added to the
3120 source package control file. Such fields will be
3121 ignored, and not copied to (for example) binary or
3122 source package control files or upload control files.
3126 If you wish to add additional unsupported fields to
3127 these output files you should use the mechanism
3132 Fields in the main source control information file with
3133 names starting <tt>X</tt>, followed by one or more of
3134 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3135 be copied to the output files. Only the part of the
3136 field name after the hyphen will be used in the output
3137 file. Where the letter <tt>B</tt> is used the field
3138 will appear in binary package control files, where the
3139 letter <tt>S</tt> is used in source package control
3140 files and where <tt>C</tt> is used in upload control
3141 (<tt>.changes</tt>) files.
3145 For example, if the main source information control file
3148 XBS-Comment: I stand between the candle and the star.
3150 then the binary and source package control files will contain the
3153 Comment: I stand between the candle and the star.
3162 <chapt id="maintainerscripts">
3163 <heading>Package maintainer scripts and installation procedure</heading>
3166 <heading>Introduction to package maintainer scripts</heading>
3169 It is possible to supply scripts as part of a package which
3170 the package management system will run for you when your
3171 package is installed, upgraded or removed.
3175 These scripts are the files <prgn>preinst</prgn>,
3176 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3177 control area of the package. They must be proper executable
3178 files; if they are scripts (which is recommended), they must
3179 start with the usual <tt>#!</tt> convention. They should be
3180 readable and executable by anyone, and not world-writable.
3184 The package management system looks at the exit status from
3185 these scripts. It is important that they exit with a
3186 non-zero status if there is an error, so that the package
3187 management system can stop its processing. For shell
3188 scripts this means that you <em>almost always</em> need to
3189 use <tt>set -e</tt> (this is usually true when writing shell
3190 scripts, in fact). It is also important, of course, that
3191 they don't exit with a non-zero status if everything went
3196 When a package is upgraded a combination of the scripts from
3197 the old and new packages is called during the upgrade
3198 procedure. If your scripts are going to be at all
3199 complicated you need to be aware of this, and may need to
3200 check the arguments to your scripts.
3204 Broadly speaking the <prgn>preinst</prgn> is called before
3205 (a particular version of) a package is installed, and the
3206 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3207 before (a version of) a package is removed and the
3208 <prgn>postrm</prgn> afterwards.
3212 Programs called from maintainer scripts should not normally
3213 have a path prepended to them. Before installation is
3214 started, the package management system checks to see if the
3215 programs <prgn>ldconfig</prgn>,
3216 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3217 and <prgn>update-rc.d</prgn> can be found via the
3218 <tt>PATH</tt> environment variable. Those programs, and any
3219 other program that one would expect to be on the
3220 <tt>PATH</tt>, should thus be invoked without an absolute
3221 pathname. Maintainer scripts should also not reset the
3222 <tt>PATH</tt>, though they might choose to modify it by
3223 prepending or appending package-specific directories. These
3224 considerations really apply to all shell scripts.</p>
3227 <sect id="idempotency">
3228 <heading>Maintainer scripts Idempotency</heading>
3231 It is necessary for the error recovery procedures that the
3232 scripts be idempotent. This means that if it is run
3233 successfully, and then it is called again, it doesn't bomb
3234 out or cause any harm, but just ensures that everything is
3235 the way it ought to be. If the first call failed, or
3236 aborted half way through for some reason, the second call
3237 should merely do the things that were left undone the first
3238 time, if any, and exit with a success status if everything
3240 This is so that if an error occurs, the user interrupts
3241 <prgn>dpkg</prgn> or some other unforeseen circumstance
3242 happens you don't leave the user with a badly-broken
3243 package when <prgn>dpkg</prgn> attempts to repeat the
3249 <sect id="controllingterminal">
3250 <heading>Controlling terminal for maintainer scripts</heading>
3253 The maintainer scripts are guaranteed to run with a
3254 controlling terminal and can interact with the user.
3255 If they need to prompt for passwords, do full-screen
3256 interaction or something similar you should do these
3257 things to and from <file>/dev/tty</file>, since
3258 <prgn>dpkg</prgn> will at some point redirect scripts'
3259 standard input and output so that it can log the
3260 installation process. Likewise, because these scripts
3261 may be executed with standard output redirected into a
3262 pipe for logging purposes, Perl scripts should set
3263 unbuffered output by setting <tt>$|=1</tt> so that the
3264 output is printed immediately rather than being
3269 Each script should return a zero exit status for
3270 success, or a nonzero one for failure.
3274 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3279 <list compact="compact">
3281 <var>new-preinst</var> <tt>install</tt>
3284 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3287 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3290 <var>old-preinst</var> <tt>abort-upgrade</tt>
3291 <var>new-version</var>
3296 <list compact="compact">
3298 <var>postinst</var> <tt>configure</tt>
3299 <var>most-recently-configured-version</var>
3302 <var>old-postinst</var> <tt>abort-upgrade</tt>
3303 <var>new-version</var>
3306 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3307 <tt>in-favour</tt> <var>package</var>
3308 <var>new-version</var>
3311 <var>deconfigured's-postinst</var>
3312 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3313 <var>failed-install-package</var> <var>version</var>
3314 <tt>removing</tt> <var>conflicting-package</var>
3320 <list compact="compact">
3322 <var>prerm</var> <tt>remove</tt>
3325 <var>old-prerm</var> <tt>upgrade</tt>
3326 <var>new-version</var>
3329 <var>new-prerm</var> <tt>failed-upgrade</tt>
3330 <var>old-version</var>
3333 <var>conflictor's-prerm</var> <tt>remove</tt>
3334 <tt>in-favour</tt> <var>package</var>
3335 <var>new-version</var>
3338 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3339 <tt>in-favour</tt> <var>package-being-installed</var>
3340 <var>version</var> <tt>removing</tt>
3341 <var>conflicting-package</var>
3347 <list compact="compact">
3349 <var>postrm</var> <tt>remove</tt>
3352 <var>postrm</var> <tt>purge</tt>
3355 <var>old-postrm</var> <tt>upgrade</tt>
3356 <var>new-version</var>
3359 <var>new-postrm</var> <tt>failed-upgrade</tt>
3360 <var>old-version</var>
3363 <var>new-postrm</var> <tt>abort-install</tt>
3366 <var>new-postrm</var> <tt>abort-install</tt>
3367 <var>old-version</var>
3370 <var>new-postrm</var> <tt>abort-upgrade</tt>
3371 <var>old-version</var>
3374 <var>disappearer's-postrm</var> <tt>disappear</tt>
3375 <var>overwriter</var>
3376 <var>overwriter-version</var>
3382 <sect id="unpackphase">
3383 <heading>Details of unpack phase of installation or upgrade</heading>
3386 The procedure on installation/upgrade/overwrite/disappear
3387 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3388 stage of <tt>dpkg --install</tt>) is as follows. In each
3389 case, if a major error occurs (unless listed below) the
3390 actions are, in general, run backwards - this means that the
3391 maintainer scripts are run with different arguments in
3392 reverse order. These are the "error unwind" calls listed
3399 If a version of the package is already installed, call
3400 <example compact="compact">
3401 <var>old-prerm</var> upgrade <var>new-version</var>
3405 If the script runs but exits with a non-zero
3406 exit status, <prgn>dpkg</prgn> will attempt:
3407 <example compact="compact">
3408 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3410 Error unwind, for both the above cases:
3411 <example compact="compact">
3412 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3419 If a "conflicting" package is being removed at the same time:
3422 If any packages depended on that conflicting
3423 package and <tt>--auto-deconfigure</tt> is
3424 specified, call, for each such package:
3425 <example compact="compact">
3426 <var>deconfigured's-prerm</var> deconfigure \
3427 in-favour <var>package-being-installed</var> <var>version</var> \
3428 removing <var>conflicting-package</var> <var>version</var>
3431 <example compact="compact">
3432 <var>deconfigured's-postinst</var> abort-deconfigure \
3433 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3434 removing <var>conflicting-package</var> <var>version</var>
3436 The deconfigured packages are marked as
3437 requiring configuration, so that if
3438 <tt>--install</tt> is used they will be
3439 configured again if possible.
3442 To prepare for removal of the conflicting package, call:
3443 <example compact="compact">
3444 <var>conflictor's-prerm</var> remove \
3445 in-favour <var>package</var> <var>new-version</var>
3448 <example compact="compact">
3449 <var>conflictor's-postinst</var> abort-remove \
3450 in-favour <var>package</var> <var>new-version</var>
3459 If the package is being upgraded, call:
3460 <example compact="compact">
3461 <var>new-preinst</var> upgrade <var>old-version</var>
3465 Otherwise, if the package had some configuration
3466 files from a previous version installed (i.e., it
3467 is in the "configuration files only" state):
3468 <example compact="compact">
3469 <var>new-preinst</var> install <var>old-version</var>
3473 Otherwise (i.e., the package was completely purged):
3474 <example compact="compact">
3475 <var>new-preinst</var> install
3477 Error unwind actions, respectively:
3478 <example compact="compact">
3479 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3480 <var>new-postrm</var> abort-install <var>old-version</var>
3481 <var>new-postrm</var> abort-install
3489 The new package's files are unpacked, overwriting any
3490 that may be on the system already, for example any
3491 from the old version of the same package or from
3492 another package. Backups of the old files are kept
3493 temporarily, and if anything goes wrong the package
3494 management system will attempt to put them back as
3495 part of the error unwind.
3499 It is an error for a package to contain files which
3500 are on the system in another package, unless
3501 <tt>Replaces</tt> is used (see <ref id="replaces">).
3503 The following paragraph is not currently the case:
3504 Currently the <tt>- - force-overwrite</tt> flag is
3505 enabled, downgrading it to a warning, but this may not
3511 It is a more serious error for a package to contain a
3512 plain file or other kind of non-directory where another
3513 package has a directory (again, unless
3514 <tt>Replaces</tt> is used). This error can be
3515 overridden if desired using
3516 <tt>--force-overwrite-dir</tt>, but this is not
3521 Packages which overwrite each other's files produce
3522 behavior which, though deterministic, is hard for the
3523 system administrator to understand. It can easily
3524 lead to "missing" programs if, for example, a package
3525 is installed which overwrites a file from another
3526 package, and is then removed again.<footnote>
3527 Part of the problem is due to what is arguably a
3528 bug in <prgn>dpkg</prgn>.
3533 A directory will never be replaced by a symbolic link
3534 to a directory or vice versa; instead, the existing
3535 state (symlink or not) will be left alone and
3536 <prgn>dpkg</prgn> will follow the symlink if there is
3545 If the package is being upgraded, call
3546 <example compact="compact">
3547 <var>old-postrm</var> upgrade <var>new-version</var>
3551 If this fails, <prgn>dpkg</prgn> will attempt:
3552 <example compact="compact">
3553 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3555 Error unwind, for both cases:
3556 <example compact="compact">
3557 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3564 This is the point of no return - if
3565 <prgn>dpkg</prgn> gets this far, it won't back off
3566 past this point if an error occurs. This will
3567 leave the package in a fairly bad state, which
3568 will require a successful re-installation to clear
3569 up, but it's when <prgn>dpkg</prgn> starts doing
3570 things that are irreversible.
3575 Any files which were in the old version of the package
3576 but not in the new are removed.
3580 The new file list replaces the old.
3584 The new maintainer scripts replace the old.
3588 Any packages all of whose files have been overwritten
3589 during the installation, and which aren't required for
3590 dependencies, are considered to have been removed.
3591 For each such package
3594 <prgn>dpkg</prgn> calls:
3595 <example compact="compact">
3596 <var>disappearer's-postrm</var> disappear \
3597 <var>overwriter</var> <var>overwriter-version</var>
3601 The package's maintainer scripts are removed.
3604 It is noted in the status database as being in a
3605 sane state, namely not installed (any conffiles
3606 it may have are ignored, rather than being
3607 removed by <prgn>dpkg</prgn>). Note that
3608 disappearing packages do not have their prerm
3609 called, because <prgn>dpkg</prgn> doesn't know
3610 in advance that the package is going to
3617 Any files in the package we're unpacking that are also
3618 listed in the file lists of other packages are removed
3619 from those lists. (This will lobotomize the file list
3620 of the "conflicting" package if there is one.)
3624 The backup files made during installation, above, are
3630 The new package's status is now sane, and recorded as
3635 Here is another point of no return - if the
3636 conflicting package's removal fails we do not unwind
3637 the rest of the installation; the conflicting package
3638 is left in a half-removed limbo.
3643 If there was a conflicting package we go and do the
3644 removal actions (described below), starting with the
3645 removal of the conflicting package's files (any that
3646 are also in the package being installed have already
3647 been removed from the conflicting package's file list,
3648 and so do not get removed now).
3654 <sect id="configdetails"><heading>Details of configuration</heading>
3657 When we configure a package (this happens with <tt>dpkg
3658 --install</tt> and <tt>dpkg --configure</tt>), we first
3659 update any <tt>conffile</tt>s and then call:
3660 <example compact="compact">
3661 <var>postinst</var> configure <var>most-recently-configured-version</var>
3666 No attempt is made to unwind after errors during
3671 If there is no most recently configured version
3672 <prgn>dpkg</prgn> will pass a null argument.
3675 Historical note: Truly ancient (pre-1997) versions of
3676 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3677 (including the angle brackets) in this case. Even older
3678 ones did not pass a second argument at all, under any
3679 circumstance. Note that upgrades using such an old dpkg
3680 version are unlikely to work for other reasons, even if
3681 this old argument behavior is handled by your postinst script.
3687 <sect id="removedetails"><heading>Details of removal and/or
3688 configuration purging</heading>
3693 <example compact="compact">
3694 <var>prerm</var> remove
3698 The package's files are removed (except <tt>conffile</tt>s).
3701 <example compact="compact">
3702 <var>postrm</var> remove
3707 All the maintainer scripts except the <prgn>postrm</prgn>
3712 If we aren't purging the package we stop here. Note
3713 that packages which have no <prgn>postrm</prgn> and no
3714 <tt>conffile</tt>s are automatically purged when
3715 removed, as there is no difference except for the
3716 <prgn>dpkg</prgn> status.
3720 The <tt>conffile</tt>s and any backup files
3721 (<tt>~</tt>-files, <tt>#*#</tt> files,
3722 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3726 <example compact="compact">
3727 <var>postrm</var> purge
3731 The package's file list is removed.
3735 If there are problems during this process, we call
3736 <example compact="compact">postinst
3737 abort-remove</example>. No other attempt is made to unwind
3738 after errors during removal.
3744 <chapt id="relationships">
3745 <heading>Declaring relationships between packages</heading>
3747 <sect id="depsyntax">
3748 <heading>Syntax of relationship fields</heading>
3751 These fields all have a uniform syntax. They are a list of
3752 package names separated by commas.
3756 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3757 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3758 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3759 control file fields of the package, which declare
3760 dependencies on other packages, the package names listed may
3761 also include lists of alternative package names, separated
3762 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3763 if any one of the alternative packages is installed, that
3764 part of the dependency is considered to be satisfied.
3768 All of the fields except for <tt>Provides</tt> may restrict
3769 their applicability to particular versions of each named
3770 package. This is done in parentheses after each individual
3771 package name; the parentheses should contain a relation from
3772 the list below followed by a version number, in the format
3773 described in <ref id="f-Version">.
3777 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3778 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3779 strictly earlier, earlier or equal, exactly equal, later or
3780 equal and strictly later, respectively. The deprecated
3781 forms <tt><</tt> and <tt>></tt> were used to mean
3782 earlier/later or equal, rather than strictly earlier/later,
3783 so they should not appear in new packages (though
3784 <prgn>dpkg</prgn> still supports them).
3788 Whitespace may appear at any point in the version
3789 specification subject to the rules in <ref
3790 id="controlsyntax">, and must appear where it's necessary to
3791 disambiguate; it is not otherwise significant. For
3792 consistency and in case of future changes to
3793 <prgn>dpkg</prgn> it is recommended that a single space be
3794 used after a version relationship and before a version
3795 number; it is also conventional to put a single space after
3796 each comma, on either side of each vertical bar, and before
3797 each open parenthesis.
3801 For example, a list of dependencies might appear as:
3802 <example compact="compact">
3805 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3810 All fields that specify build-time relationships
3811 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3812 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3813 may be restricted to a certain set of architectures. This
3814 is indicated in brackets after each individual package name and
3815 the optional version specification. The brackets enclose a
3816 list of Debian architecture names separated by whitespace.
3817 Exclamation marks may be prepended to each of the names.
3818 (It is not permitted for some names to be prepended with
3819 exclamation marks and others not.) If the current Debian
3820 host architecture is not in this list and there are no
3821 exclamation marks in the list, or it is in the list with a
3822 prepended exclamation mark, the package name and the
3823 associated version specification are ignored completely for
3824 the purposes of defining the relationships.
3829 <example compact="compact">
3831 Build-Depends-Indep: texinfo
3832 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3833 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3838 Note that the binary package relationship fields such as
3839 <tt>Depends</tt> appear in one of the binary package
3840 sections of the control file, whereas the build-time
3841 relationships such as <tt>Build-Depends</tt> appear in the
3842 source package section of the control file (which is the
3847 <sect id="binarydeps">
3848 <heading>Binary Dependencies - <tt>Depends</tt>,
3849 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3850 <tt>Pre-Depends</tt>
3854 Packages can declare in their control file that they have
3855 certain relationships to other packages - for example, that
3856 they may not be installed at the same time as certain other
3857 packages, and/or that they depend on the presence of others.
3861 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3862 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3863 <tt>Conflicts</tt> control file fields.
3867 These six fields are used to declare a dependency
3868 relationship by one package on another. Except for
3869 <tt>Enhances</tt>, they appear in the depending (binary)
3870 package's control file. (<tt>Enhances</tt> appears in the
3871 recommending package's control file.)
3875 A <tt>Depends</tt> field takes effect <em>only</em> when a
3876 package is to be configured. It does not prevent a package
3877 being on the system in an unconfigured state while its
3878 dependencies are unsatisfied, and it is possible to replace
3879 a package whose dependencies are satisfied and which is
3880 properly installed with a different version whose
3881 dependencies are not and cannot be satisfied; when this is
3882 done the depending package will be left unconfigured (since
3883 attempts to configure it will give errors) and will not
3884 function properly. If it is necessary, a
3885 <tt>Pre-Depends</tt> field can be used, which has a partial
3886 effect even when a package is being unpacked, as explained
3887 in detail below. (The other three dependency fields,
3888 <tt>Recommends</tt>, <tt>Suggests</tt> and
3889 <tt>Enhances</tt>, are only used by the various front-ends
3890 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3894 For this reason packages in an installation run are usually
3895 all unpacked first and all configured later; this gives
3896 later versions of packages with dependencies on later
3897 versions of other packages the opportunity to have their
3898 dependencies satisfied.
3902 The <tt>Depends</tt> field thus allows package maintainers
3903 to impose an order in which packages should be configured.
3907 The meaning of the five dependency fields is as follows:
3909 <tag><tt>Depends</tt></tag>
3912 This declares an absolute dependency. A package will
3913 not be configured unless all of the packages listed in
3914 its <tt>Depends</tt> field have been correctly
3919 The <tt>Depends</tt> field should be used if the
3920 depended-on package is required for the depending
3921 package to provide a significant amount of
3926 The <tt>Depends</tt> field should also be used if the
3927 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3928 <prgn>postrm</prgn> scripts require the package to be
3929 present in order to run. Note, however, that the
3930 <prgn>postrm</prgn> cannot rely on any non-essential
3931 packages to be present during the <tt>purge</tt>
3935 <tag><tt>Recommends</tt></tag>
3938 This declares a strong, but not absolute, dependency.
3942 The <tt>Recommends</tt> field should list packages
3943 that would be found together with this one in all but
3944 unusual installations.
3948 <tag><tt>Suggests</tt></tag>
3950 This is used to declare that one package may be more
3951 useful with one or more others. Using this field
3952 tells the packaging system and the user that the
3953 listed packages are related to this one and can
3954 perhaps enhance its usefulness, but that installing
3955 this one without them is perfectly reasonable.
3958 <tag><tt>Enhances</tt></tag>
3960 This field is similar to Suggests but works in the
3961 opposite direction. It is used to declare that a
3962 package can enhance the functionality of another
3966 <tag><tt>Pre-Depends</tt></tag>
3969 This field is like <tt>Depends</tt>, except that it
3970 also forces <prgn>dpkg</prgn> to complete installation
3971 of the packages named before even starting the
3972 installation of the package which declares the
3973 pre-dependency, as follows:
3977 When a package declaring a pre-dependency is about to
3978 be <em>unpacked</em> the pre-dependency can be
3979 satisfied if the depended-on package is either fully
3980 configured, <em>or even if</em> the depended-on
3981 package(s) are only unpacked or half-configured,
3982 provided that they have been configured correctly at
3983 some point in the past (and not removed or partially
3984 removed since). In this case, both the
3985 previously-configured and currently unpacked or
3986 half-configured versions must satisfy any version
3987 clause in the <tt>Pre-Depends</tt> field.
3991 When the package declaring a pre-dependency is about
3992 to be <em>configured</em>, the pre-dependency will be
3993 treated as a normal <tt>Depends</tt>, that is, it will
3994 be considered satisfied only if the depended-on
3995 package has been correctly configured.
3999 <tt>Pre-Depends</tt> should be used sparingly,
4000 preferably only by packages whose premature upgrade or
4001 installation would hamper the ability of the system to
4002 continue with any upgrade that might be in progress.
4006 <tt>Pre-Depends</tt> are also required if the
4007 <prgn>preinst</prgn> script depends on the named
4008 package. It is best to avoid this situation if
4016 When selecting which level of dependency to use you should
4017 consider how important the depended-on package is to the
4018 functionality of the one declaring the dependency. Some
4019 packages are composed of components of varying degrees of
4020 importance. Such a package should list using
4021 <tt>Depends</tt> the package(s) which are required by the
4022 more important components. The other components'
4023 requirements may be mentioned as Suggestions or
4024 Recommendations, as appropriate to the components' relative
4029 <sect id="conflicts">
4030 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4033 When one binary package declares a conflict with another
4034 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4035 refuse to allow them to be installed on the system at the
4040 If one package is to be installed, the other must be removed
4041 first - if the package being installed is marked as
4042 replacing (see <ref id="replaces">) the one on the system,
4043 or the one on the system is marked as deselected, or both
4044 packages are marked <tt>Essential</tt>, then
4045 <prgn>dpkg</prgn> will automatically remove the package
4046 which is causing the conflict, otherwise it will halt the
4047 installation of the new package with an error. This
4048 mechanism is specifically designed to produce an error when
4049 the installed package is <tt>Essential</tt>, but the new
4054 A package will not cause a conflict merely because its
4055 configuration files are still installed; it must be at least
4060 A special exception is made for packages which declare a
4061 conflict with their own package name, or with a virtual
4062 package which they provide (see below): this does not
4063 prevent their installation, and allows a package to conflict
4064 with others providing a replacement for it. You use this
4065 feature when you want the package in question to be the only
4066 package providing some feature.
4070 A <tt>Conflicts</tt> entry should almost never have an
4071 "earlier than" version clause. This would prevent
4072 <prgn>dpkg</prgn> from upgrading or installing the package
4073 which declared such a conflict until the upgrade or removal
4074 of the conflicted-with package had been completed.
4078 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4082 As well as the names of actual ("concrete") packages, the
4083 package relationship fields <tt>Depends</tt>,
4084 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4085 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4086 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4087 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4088 may mention "virtual packages".
4092 A <em>virtual package</em> is one which appears in the
4093 <tt>Provides</tt> control file field of another package.
4094 The effect is as if the package(s) which provide a
4095 particular virtual package name had been listed by name
4096 everywhere the virtual package name appears. (See also <ref
4101 If there are both concrete and virtual packages of the same
4102 name, then the dependency may be satisfied (or the conflict
4103 caused) by either the concrete package with the name in
4104 question or any other concrete package which provides the
4105 virtual package with the name in question. This is so that,
4106 for example, supposing we have
4107 <example compact="compact">
4111 and someone else releases an enhanced version of the
4112 <tt>bar</tt> package (for example, a non-US variant), they
4114 <example compact="compact">
4118 and the <tt>bar-plus</tt> package will now also satisfy the
4119 dependency for the <tt>foo</tt> package.
4123 If a dependency or a conflict has a version number attached
4124 then only real packages will be considered to see whether
4125 the relationship is satisfied (or the prohibition violated,
4126 for a conflict) - it is assumed that a real package which
4127 provides the virtual package is not of the "right" version.
4128 So, a <tt>Provides</tt> field may not contain version
4129 numbers, and the version number of the concrete package
4130 which provides a particular virtual package will not be
4131 looked at when considering a dependency on or conflict with
4132 the virtual package name.
4136 It is likely that the ability will be added in a future
4137 release of <prgn>dpkg</prgn> to specify a version number for
4138 each virtual package it provides. This feature is not yet
4139 present, however, and is expected to be used only
4144 If you want to specify which of a set of real packages
4145 should be the default to satisfy a particular dependency on
4146 a virtual package, you should list the real package as an
4147 alternative before the virtual one.
4152 <sect id="replaces"><heading>Overwriting files and replacing
4153 packages - <tt>Replaces</tt></heading>
4156 Packages can declare in their control file that they should
4157 overwrite files in certain other packages, or completely
4158 replace other packages. The <tt>Replaces</tt> control file
4159 field has these two distinct purposes.
4162 <sect1><heading>Overwriting files in other packages</heading>
4165 Firstly, as mentioned before, it is usually an error for a
4166 package to contain files which are on the system in
4171 However, if the overwriting package declares that it
4172 <tt>Replaces</tt> the one containing the file being
4173 overwritten, then <prgn>dpkg</prgn> will replace the file
4174 from the old package with that from the new. The file
4175 will no longer be listed as "owned" by the old package.
4179 If a package is completely replaced in this way, so that
4180 <prgn>dpkg</prgn> does not know of any files it still
4181 contains, it is considered to have "disappeared". It will
4182 be marked as not wanted on the system (selected for
4183 removal) and not installed. Any <tt>conffile</tt>s
4184 details noted for the package will be ignored, as they
4185 will have been taken over by the overwriting package. The
4186 package's <prgn>postrm</prgn> script will be run with a
4187 special argument to allow the package to do any final
4188 cleanup required. See <ref id="mscriptsinstact">.
4191 Replaces is a one way relationship -- you have to
4192 install the replacing package after the replaced
4199 For this usage of <tt>Replaces</tt>, virtual packages (see
4200 <ref id="virtual">) are not considered when looking at a
4201 <tt>Replaces</tt> field - the packages declared as being
4202 replaced must be mentioned by their real names.
4206 Furthermore, this usage of <tt>Replaces</tt> only takes
4207 effect when both packages are at least partially on the
4208 system at once, so that it can only happen if they do not
4209 conflict or if the conflict has been overridden.
4214 <sect1><heading>Replacing whole packages, forcing their
4218 Secondly, <tt>Replaces</tt> allows the packaging system to
4219 resolve which package should be removed when there is a
4220 conflict - see <ref id="conflicts">. This usage only
4221 takes effect when the two packages <em>do</em> conflict,
4222 so that the two usages of this field do not interfere with
4227 In this situation, the package declared as being replaced
4228 can be a virtual package, so for example, all mail
4229 transport agents (MTAs) would have the following fields in
4230 their control files:
4231 <example compact="compact">
4232 Provides: mail-transport-agent
4233 Conflicts: mail-transport-agent
4234 Replaces: mail-transport-agent
4236 ensuring that only one MTA can be installed at any one
4241 <sect id="sourcebinarydeps">
4242 <heading>Relationships between source and binary packages -
4243 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4244 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4248 Source packages that require certain binary packages to be
4249 installed or absent at the time of building the package
4250 can declare relationships to those binary packages.
4254 This is done using the <tt>Build-Depends</tt>,
4255 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4256 <tt>Build-Conflicts-Indep</tt> control file fields.
4260 Build-dependencies on "build-essential" binary packages can be
4261 omitted. Please see <ref id="pkg-relations"> for more information.
4265 The dependencies and conflicts they define must be satisfied
4266 (as defined earlier for binary packages) in order to invoke
4267 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4269 If you make "build-arch" or "binary-arch", you need
4270 Build-Depends. If you make "build-indep" or
4271 "binary-indep", you need Build-Depends and
4272 Build-Depends-Indep. If you make "build" or "binary",
4276 There is no Build-Depends-Arch; the autobuilders will
4277 only need the Build-Depends if they know how to build
4278 only build-arch and binary-arch. Anyone building the
4279 build-indep/binary-indep targets is basically assumed to
4280 be building the whole package and so installs all build
4284 The purpose of the original split, I recall, was so that
4285 the autobuilders wouldn't need to install extra packages
4286 needed only for the binary-indep targets. But without a
4287 build-arch/build-indep split, this didn't work, since
4288 most of the work is done in the build target, not in the
4294 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4296 The <tt>Build-Depends</tt> and
4297 <tt>Build-Conflicts</tt> fields must be satisfied when
4298 any of the following targets is invoked:
4299 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4300 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4301 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4303 <tag><tt>Build-Depends-Indep</tt>,
4304 <tt>Build-Conflicts-Indep</tt></tag>
4306 The <tt>Build-Depends-Indep</tt> and
4307 <tt>Build-Conflicts-Indep</tt> fields must be
4308 satisfied when any of the following targets is
4309 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4310 <tt>binary</tt> and <tt>binary-indep</tt>.
4320 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4323 Packages containing shared libraries must be constructed with
4324 a little care to make sure that the shared library is always
4325 available. This is especially important for packages whose
4326 shared libraries are vitally important, such as the C library
4327 (currently <tt>libc6</tt>).
4331 Packages involving shared libraries should be split up into
4332 several binary packages. This section mostly deals with how
4333 this separation is to be accomplished; rules for files within
4334 the shared library packages are in <ref id="libraries"> instead.
4337 <sect id="sharedlibs-runtime">
4338 <heading>Run-time shared libraries</heading>
4341 The run-time shared library needs to be placed in a package called
4342 <package><var>libraryname</var><var>soversion</var></package>, where
4343 <file><var>soversion</var></file> is the version number in the
4344 soname of the shared library<footnote>
4345 The soname is the shared object name: it's the thing
4346 that has to match exactly between building an executable
4347 and running it for the dynamic linker to be able run the
4348 program. For example, if the soname of the library is
4349 <file>libfoo.so.6</file>, the library package would be
4350 called <file>libfoo6</file>.
4352 Alternatively, if it would be confusing to directly append
4353 <var>soversion</var> to <var>libraryname</var> (e.g. because
4354 <var>libraryname</var> itself ends in a number), you may use
4355 <package><var>libraryname</var>-<var>soversion</var></package> and
4356 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4361 If you have several shared libraries built from the same
4362 source tree you may lump them all together into a single
4363 shared library package, provided that you change all of
4364 their sonames at once (so that you don't get filename
4365 clashes if you try to install different versions of the
4366 combined shared libraries package).
4370 The package should install the shared libraries under
4371 their normal names. For example, the <package>libgdbm3</package>
4372 package should install <file>libgdbm.so.3.0.0</file> as
4373 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4374 renamed or re-linked by any <prgn>prerm</prgn> or
4375 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4376 of renaming things safely without affecting running programs,
4377 and attempts to interfere with this are likely to lead to
4382 Shared libraries should not be installed executable, since
4383 the dynamic linker does not require this and trying to
4384 execute a shared library usually results in a core dump.
4388 The run-time library package should include the symbolic link that
4389 <prgn>ldconfig</prgn> would create for the shared libraries.
4390 For example, the <package>libgdbm3</package> package should include
4391 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4392 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4393 linker (for example <prgn>ld.so</prgn> or
4394 <prgn>ld-linux.so.*</prgn>) can find the library between the
4395 time that <prgn>dpkg</prgn> installs it and the time that
4396 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4398 The package management system requires the library to be
4399 placed before the symbolic link pointing to it in the
4400 <file>.deb</file> file. This is so that when
4401 <prgn>dpkg</prgn> comes to install the symlink
4402 (overwriting the previous symlink pointing at an older
4403 version of the library), the new shared library is already
4404 in place. In the past, this was achieved by creating the
4405 library in the temporary packaging directory before
4406 creating the symlink. Unfortunately, this was not always
4407 effective, since the building of the tar file in the
4408 <file>.deb</file> depended on the behavior of the underlying
4409 file system. Some file systems (such as reiserfs) reorder
4410 the files so that the order of creation is forgotten.
4411 Since version 1.7.0, <prgn>dpkg</prgn>
4412 reorders the files itself as necessary when building a
4413 package. Thus it is no longer important to concern
4414 oneself with the order of file creation.
4418 <sect1 id="ldconfig">
4419 <heading><tt>ldconfig</tt></heading>
4422 Any package installing shared libraries in one of the default
4423 library directories of the dynamic linker (which are currently
4424 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4425 listed in <file>/etc/ld.so.conf</file><footnote>
4427 <list compact="compact">
4428 <item>/usr/X11R6/lib/Xaw3d</item>
4429 <item>/usr/local/lib</item>
4430 <item>/usr/lib/libc5-compat</item>
4431 <item>/lib/libc5-compat</item>
4432 <item>/usr/X11R6/lib</item>
4435 must use <prgn>ldconfig</prgn> to update the shared library
4440 The package must call <prgn>ldconfig</prgn> in the
4441 <prgn>postinst</prgn> script if the first argument is
4442 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4443 optionally invoke <prgn>ldconfig</prgn> at other times. The
4444 package should call <prgn>ldconfig</prgn> in the
4445 <prgn>postrm</prgn> script if the first argument is
4446 <tt>remove</tt>. The maintainer scripts must not invoke
4447 <prgn>ldconfig</prgn> under any circumstances other than those
4448 described in this paragraph.<footnote>
4450 During install or upgrade, the preinst is called before
4451 the new files are installed, so calling "ldconfig" is
4452 pointless. The preinst of an existing package can also be
4453 called if an upgrade fails. However, this happens during
4454 the critical time when a shared libs may exist on-disk
4455 under a temporary name. Thus, it is dangerous and
4456 forbidden by current policy to call "ldconfig" at this
4461 When a package is installed or upgraded, "postinst
4462 configure" runs after the new files are safely on-disk.
4463 Since it is perfectly safe to invoke ldconfig
4464 unconditionally in a postinst, it is OK for a package to
4465 simply put ldconfig in its postinst without checking the
4466 argument. The postinst can also be called to recover from
4467 a failed upgrade. This happens before any new files are
4468 unpacked, so there is no reason to call "ldconfig" at this
4473 For a package that is being removed, prerm is
4474 called with all the files intact, so calling ldconfig is
4475 useless. The other calls to "prerm" happen in the case of
4476 upgrade at a time when all the files of the old package
4477 are on-disk, so again calling "ldconfig" is pointless.
4481 postrm, on the other hand, is called with the "remove"
4482 argument just after the files are removed, so this is the
4483 proper time to call "ldconfig" to notify the system of the
4484 fact shared libraries from the package are removed.
4485 The postrm can be called at several other times. At the
4486 time of "postrm purge", "postrm abort-install", or "postrm
4487 abort-upgrade", calling "ldconfig" is useless because the
4488 shared lib files are not on-disk. However, when "postrm"
4489 is invoked with arguments "upgrade", "failed-upgrade", or
4490 "disappear", a shared lib may exist on-disk under a
4499 <sect id="sharedlibs-runtime-progs">
4500 <heading>Run-time support programs</heading>
4503 If your package has some run-time support programs which use
4504 the shared library you must not put them in the shared
4505 library package. If you do that then you won't be able to
4506 install several versions of the shared library without
4507 getting filename clashes.
4511 Instead, either create another package for the runtime binaries
4512 (this package might typically be named
4513 <package><var>libraryname</var>-runtime</package>; note the absence
4514 of the <var>soversion</var> in the package name), or if the
4515 development package is small, include them in there.
4519 <sect id="sharedlibs-static">
4520 <heading>Static libraries</heading>
4523 The static library (<file><var>libraryname.a</var></file>)
4524 is usually provided in addition to the shared version.
4525 It is placed into the development package (see below).
4529 In some cases, it is acceptable for a library to be
4530 available in static form only; these cases include:
4532 <item>libraries for languages whose shared library support
4533 is immature or unstable</item>
4534 <item>libraries whose interfaces are in flux or under
4535 development (commonly the case when the library's
4536 major version number is zero, or where the ABI breaks
4537 across patchlevels)</item>
4538 <item>libraries which are explicitly intended to be
4539 available only in static form by their upstream
4544 <sect id="sharedlibs-dev">
4545 <heading>Development files</heading>
4548 The development files associated to a shared library need to be
4549 placed in a package called
4550 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4551 or if you prefer only to support one development version at a
4552 time, <package><var>libraryname</var>-dev</package>.
4556 In case several development versions of a library exist, you may
4557 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4558 <ref id="conflicts">) to ensure that the user only installs one
4559 development version at a time (as different development versions are
4560 likely to have the same header files in them, which would cause a
4561 filename clash if both were installed).
4565 The development package should contain a symlink for the associated
4566 shared library without a version number. For example, the
4567 <package>libgdbm-dev</package> package should include a symlink
4568 from <file>/usr/lib/libgdbm.so</file> to
4569 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4570 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4571 <file>libgdbm.so</file> when compiling dynamically.
4575 <sect id="sharedlibs-intradeps">
4576 <heading>Dependencies between the packages of the same library</heading>
4579 Typically the development version should have an exact
4580 version dependency on the runtime library, to make sure that
4581 compilation and linking happens correctly. The
4582 <tt>${Source-Version}</tt> substitution variable can be
4583 useful for this purpose.
4587 <sect id="sharedlibs-shlibdeps">
4588 <heading>Dependencies between the library and other packages -
4589 the <tt>shlibs</tt> system</heading>
4592 If a package contains a binary or library which links to a
4593 shared library, we must ensure that when the package is
4594 installed on the system, all of the libraries needed are
4595 also installed. This requirement led to the creation of the
4596 <tt>shlibs</tt> system, which is very simple in its design:
4597 any package which <em>provides</em> a shared library also
4598 provides information on the package dependencies required to
4599 ensure the presence of this library, and any package which
4600 <em>uses</em> a shared library uses this information to
4601 determine the dependencies it requires. The files which
4602 contain the mapping from shared libraries to the necessary
4603 dependency information are called <file>shlibs</file> files.
4607 Thus, when a package is built which contains any shared
4608 libraries, it must provide a <file>shlibs</file> file for other
4609 packages to use, and when a package is built which contains
4610 any shared libraries or compiled binaries, it must run
4611 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4612 on these to determine the libraries used and hence the
4613 dependencies needed by this package.<footnote>
4615 In the past, the shared libraries linked to were
4616 determined by calling <prgn>ldd</prgn>, but now
4617 <prgn>objdump</prgn> is used to do this. The only
4618 change this makes to package building is that
4619 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4620 libraries, whereas in the past this was unnecessary.
4621 The rest of this footnote explains the advantage that
4626 We say that a binary <tt>foo</tt> <em>directly</em> uses
4627 a library <tt>libbar</tt> if it is explicitly linked
4628 with that library (that is, it uses the flag
4629 <tt>-lbar</tt> during the linking stage). Other
4630 libraries that are needed by <tt>libbar</tt> are linked
4631 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4632 linker will load them automatically when it loads
4633 <tt>libbar</tt>. A package should depend on
4634 the libraries it directly uses, and the dependencies for
4635 those libraries should automatically pull in the other
4640 Unfortunately, the <prgn>ldd</prgn> program shows both
4641 the directly and indirectly used libraries, meaning that
4642 the dependencies determined included both direct and
4643 indirect dependencies. The use of <prgn>objdump</prgn>
4644 avoids this problem by determining only the directly
4649 A good example of where this helps is the following. We
4650 could update <tt>libimlib</tt> with a new version that
4651 supports a new graphics format called dgf (but retaining
4652 the same major version number). If we used the old
4653 <prgn>ldd</prgn> method, every package that uses
4654 <tt>libimlib</tt> would need to be recompiled so it
4655 would also depend on <tt>libdgf</tt> or it wouldn't run
4656 due to missing symbols. However with the new system,
4657 packages using <tt>libimlib</tt> can rely on
4658 <tt>libimlib</tt> itself having the dependency on
4659 <tt>libdgf</tt> and so they would not need rebuilding.
4665 In the following sections, we will first describe where the
4666 various <tt>shlibs</tt> files are to be found, then how to
4667 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4668 file format and how to create them if your package contains a
4673 <heading>The <tt>shlibs</tt> files present on the system</heading>
4676 There are several places where <tt>shlibs</tt> files are
4677 found. The following list gives them in the order in which
4679 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4680 (The first one which gives the required information is used.)
4686 <p><file>debian/shlibs.local</file></p>
4689 This lists overrides for this package. Its use is
4690 described below (see <ref id="shlibslocal">).
4695 <p><file>/etc/dpkg/shlibs.override</file></p>
4698 This lists global overrides. This list is normally
4699 empty. It is maintained by the local system
4705 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4708 When packages are being built, any
4709 <file>debian/shlibs</file> files are copied into the
4710 control file area of the temporary build directory and
4711 given the name <file>shlibs</file>. These files give
4712 details of any shared libraries included in the
4714 An example may help here. Let us say that the
4715 source package <tt>foo</tt> generates two binary
4716 packages, <tt>libfoo2</tt> and
4717 <tt>foo-runtime</tt>. When building the binary
4718 packages, the two packages are created in the
4719 directories <file>debian/libfoo2</file> and
4720 <file>debian/foo-runtime</file> respectively.
4721 (<file>debian/tmp</file> could be used instead of one
4722 of these.) Since <tt>libfoo2</tt> provides the
4723 <tt>libfoo</tt> shared library, it will require a
4724 <tt>shlibs</tt> file, which will be installed in
4725 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4727 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4728 when <prgn>dpkg-shlibdeps</prgn> is run on the
4730 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4732 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4733 determine whether <tt>foo-prog</tt>'s library
4734 dependencies are satisfied by any of the libraries
4735 provided by <tt>libfoo2</tt>. For this reason,
4736 <prgn>dpkg-shlibdeps</prgn> must only be run once
4737 all of the individual binary packages'
4738 <tt>shlibs</tt> files have been installed into the
4745 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4748 These are the <file>shlibs</file> files corresponding to
4749 all of the packages installed on the system, and are
4750 maintained by the relevant package maintainers.
4755 <p><file>/etc/dpkg/shlibs.default</file></p>
4758 This file lists any shared libraries whose packages
4759 have failed to provide correct <file>shlibs</file> files.
4760 It was used when the <file>shlibs</file> setup was first
4761 introduced, but it is now normally empty. It is
4762 maintained by the <tt>dpkg</tt> maintainer.
4770 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4771 <file>shlibs</file> files</heading>
4775 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4776 into your <file>debian/rules</file> file. If your package
4777 contains only compiled binaries and libraries (but no scripts),
4778 you can use a command such as:
4779 <example compact="compact">
4780 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4781 debian/tmp/usr/lib/*
4783 Otherwise, you will need to explicitly list the compiled
4784 binaries and libraries.<footnote>
4785 If you are using <tt>debhelper</tt>, the
4786 <prgn>dh_shlibdeps</prgn> program will do this work for
4787 you. It will also correctly handle multi-binary
4793 This command puts the dependency information into the
4794 <file>debian/substvars</file> file, which is then used by
4795 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4796 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4797 field in the control file for this to work.
4801 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4802 done. If it does complain you might need to create your own
4803 <file>debian/shlibs.local</file> file, as explained below (see
4804 <ref id="shlibslocal">).
4808 If you have multiple binary packages, you will need to call
4809 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4810 compiled libraries or binaries. In such a case, you will
4811 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4812 utilities to specify a different <file>substvars</file> file.
4816 For more details on dpkg-shlibdeps, please see
4817 <ref id="pkg-dpkg-shlibdeps"> and
4818 <manref name="dpkg-shlibdeps" section="1">.
4823 <heading>The <file>shlibs</file> File Format</heading>
4826 Each <file>shlibs</file> file has the same format. Lines
4827 beginning with <tt>#</tt> are considered to be comments and
4828 are ignored. Each line is of the form:
4829 <example compact="compact">
4830 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4835 We will explain this by reference to the example of the
4836 <tt>zlib1g</tt> package, which (at the time of writing)
4837 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4841 <var>library-name</var> is the name of the shared library,
4842 in this case <tt>libz</tt>. (This must match the name part
4843 of the soname, see below.)
4847 <var>soname-version-number</var> is the version part of the
4848 soname of the library. The soname is the thing that must
4849 exactly match for the library to be recognized by the
4850 dynamic linker, and is usually of the form
4851 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4852 example, <tt>libz.so.1</tt>.<footnote>
4853 This can be determined using the command
4854 <example compact="compact">
4855 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4858 The version part is the part which comes after
4859 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4863 <var>dependencies</var> has the same syntax as a dependency
4864 field in a binary package control file. It should give
4865 details of which packages are required to satisfy a binary
4866 built against the version of the library contained in the
4867 package. See <ref id="depsyntax"> for details.
4871 In our example, if the first version of the <tt>zlib1g</tt>
4872 package which contained a minor number of at least
4873 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4874 <tt>shlibs</tt> entry for this library could say:
4875 <example compact="compact">
4876 libz 1 zlib1g (>= 1:1.1.3)
4878 The version-specific dependency is to avoid warnings from
4879 the dynamic linker about using older shared libraries with
4885 <heading>Providing a <file>shlibs</file> file</heading>
4888 If your package provides a shared library, you should create
4889 a <file>shlibs</file> file following the format described above.
4890 It is usual to call this file <file>debian/shlibs</file> (but if
4891 you have multiple binary packages, you might want to call it
4892 <file>debian/shlibs.<var>package</var></file> instead). Then
4893 let <file>debian/rules</file> install it in the control area:
4894 <example compact="compact">
4895 install -m644 debian/shlibs debian/tmp/DEBIAN
4897 or, in the case of a multi-binary package:
4898 <example compact="compact">
4899 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4901 An alternative way of doing this is to create the
4902 <file>shlibs</file> file in the control area directly from
4903 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4904 file at all,<footnote>
4905 This is what <prgn>dh_makeshlibs</prgn> in the
4906 <tt>debhelper</tt> suite does.
4908 since the <file>debian/shlibs</file> file itself is ignored by
4909 <prgn>dpkg-shlibdeps</prgn>.
4913 As <prgn>dpkg-shlibdeps</prgn> reads the
4914 <file>DEBIAN/shlibs</file> files in all of the binary packages
4915 being built from this source package, all of the
4916 <file>DEBIAN/shlibs</file> files should be installed before
4917 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4922 <sect1 id="shlibslocal">
4923 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4926 This file is intended only as a <em>temporary</em> fix if
4927 your binaries or libraries depend on a library whose package
4928 does not yet provide a correct <file>shlibs</file> file.
4932 We will assume that you are trying to package a binary
4933 <tt>foo</tt>. When you try running
4934 <prgn>dpkg-shlibdeps</prgn> you get the following error
4935 message (<tt>-O</tt> displays the dependency information on
4936 <tt>stdout</tt> instead of writing it to
4937 <tt>debian/substvars</tt>, and the lines have been wrapped
4938 for ease of reading):
4939 <example compact="compact">
4940 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4941 dpkg-shlibdeps: warning: unable to find dependency
4942 information for shared library libbar (soname 1,
4943 path /usr/lib/libbar.so.1, dependency field Depends)
4944 shlibs:Depends=libc6 (>= 2.2.2-2)
4946 You can then run <prgn>ldd</prgn> on the binary to find the
4947 full location of the library concerned:
4948 <example compact="compact">
4950 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4951 libc.so.6 => /lib/libc.so.6 (0x40032000)
4952 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4954 So the <prgn>foo</prgn> binary depends on the
4955 <prgn>libbar</prgn> shared library, but no package seems to
4956 provide a <file>*.shlibs</file> file handling
4957 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4958 determine the package responsible:
4959 <example compact="compact">
4960 $ dpkg -S /usr/lib/libbar.so.1
4961 bar1: /usr/lib/libbar.so.1
4962 $ dpkg -s bar1 | grep Version
4965 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4966 is the one we are using. Now we can file a bug against the
4967 <tt>bar1</tt> package and create our own
4968 <file>debian/shlibs.local</file> to locally fix the problem.
4969 Including the following line into your
4970 <file>debian/shlibs.local</file> file:
4971 <example compact="compact">
4972 libbar 1 bar1 (>= 1.0-1)
4974 should allow the package build to work.
4978 As soon as the maintainer of <tt>bar1</tt> provides a
4979 correct <file>shlibs</file> file, you should remove this line
4980 from your <file>debian/shlibs.local</file> file. (You should
4981 probably also then have a versioned <tt>Build-Depends</tt>
4982 on <tt>bar1</tt> to help ensure that others do not have the
4983 same problem building your package.)
4992 <chapt id="opersys"><heading>The Operating System</heading>
4995 <heading>Filesystem hierarchy</heading>
4999 <heading>Filesystem Structure</heading>
5002 The location of all installed files and directories must
5003 comply with the Filesystem Hierarchy Standard (FHS),
5004 version 2.1, except where doing so would violate other
5005 terms of Debian Policy. The version of this document
5006 referred here can be found in the <tt>debian-policy</tt>
5008 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5009 name="FHS (Debian copy)"> alongside this manual (or, if
5010 you have the <package>debian-policy</package> installed,
5012 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5013 (local copy)">). The
5014 latest version, which may be a more recent version, may
5016 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5017 Specific questions about following the standard may be
5018 asked on the <tt>debian-devel</tt> mailing list, or
5019 referred to the FHS mailing list (see the
5020 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5026 <heading>Site-specific programs</heading>
5029 As mandated by the FHS, packages must not place any
5030 files in <file>/usr/local</file>, either by putting them in
5031 the file system archive to be unpacked by <prgn>dpkg</prgn>
5032 or by manipulating them in their maintainer scripts.
5036 However, the package may create empty directories below
5037 <file>/usr/local</file> so that the system administrator knows
5038 where to place site-specific files. These directories
5039 should be removed on package removal if they are
5044 Note, that this applies only to directories <em>below</em>
5045 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5046 Packages must not create sub-directories in the directory
5047 <file>/usr/local</file> itself, except those listed in FHS,
5048 section 4.5. However, you may create directories below
5049 them as you wish. You must not remove any of the
5050 directories listed in 4.5, even if you created them.
5054 Since <file>/usr/local</file> can be mounted read-only from a
5055 remote server, these directories must be created and
5056 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5057 maintainer scripts and not be included in the
5058 <file>.deb</file> archive. These scripts must not fail if
5059 either of these operations fail.
5063 For example, the <tt>emacsen-common</tt> package could
5064 contain something like
5065 <example compact="compact">
5066 if [ ! -e /usr/local/share/emacs ]
5068 if mkdir /usr/local/share/emacs 2>/dev/null
5070 chown root:staff /usr/local/share/emacs
5071 chmod 2775 /usr/local/share/emacs
5075 in its <prgn>postinst</prgn> script, and
5076 <example compact="compact">
5077 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5078 rmdir /usr/local/share/emacs 2>/dev/null || true
5080 in the <prgn>prerm</prgn> script. (Note that this form is
5081 used to ensure that if the script is interrupted, the
5082 directory <file>/usr/local/share/emacs</file> will still be
5087 If you do create a directory in <file>/usr/local</file> for
5088 local additions to a package, you should ensure that
5089 settings in <file>/usr/local</file> take precedence over the
5090 equivalents in <file>/usr</file>.
5094 However, because <file>/usr/local</file> and its contents are
5095 for exclusive use of the local administrator, a package
5096 must not rely on the presence or absence of files or
5097 directories in <file>/usr/local</file> for normal operation.
5101 The <file>/usr/local</file> directory itself and all the
5102 subdirectories created by the package should (by default) have
5103 permissions 2775 (group-writable and set-group-id) and be
5104 owned by <tt>root.staff</tt>.
5109 <heading>The system-wide mail directory</heading>
5111 The system-wide mail directory is <file>/var/mail</file>. This
5112 directory is part of the base system and should not owned
5113 by any particular mail agents. The use of the old
5114 location <file>/var/spool/mail</file> is deprecated, even
5115 though the spool may still be physically located there.
5116 To maintain partial upgrade compatibility for systems
5117 which have <file>/var/spool/mail</file> as their physical mail
5118 spool, packages using <file>/var/mail</file> must depend on
5119 either <package>libc6</package> (>= 2.1.3-13), or on
5120 <package>base-files</package> (>= 2.2.0), or on later
5121 versions of either one of these packages.
5127 <heading>Users and groups</heading>
5130 <heading>Introduction</heading>
5132 The Debian system can be configured to use either plain or
5137 Some user ids (UIDs) and group ids (GIDs) are reserved
5138 globally for use by certain packages. Because some
5139 packages need to include files which are owned by these
5140 users or groups, or need the ids compiled into binaries,
5141 these ids must be used on any Debian system only for the
5142 purpose for which they are allocated. This is a serious
5143 restriction, and we should avoid getting in the way of
5144 local administration policies. In particular, many sites
5145 allocate users and/or local system groups starting at 100.
5149 Apart from this we should have dynamically allocated ids,
5150 which should by default be arranged in some sensible
5151 order, but the behavior should be configurable.
5155 Packages other than <tt>base-passwd</tt> must not modify
5156 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5157 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5162 <heading>UID and GID classes</heading>
5164 The UID and GID numbers are divided into classes as
5170 Globally allocated by the Debian project, the same
5171 on every Debian system. These ids will appear in
5172 the <file>passwd</file> and <file>group</file> files of all
5173 Debian systems, new ids in this range being added
5174 automatically as the <tt>base-passwd</tt> package is
5179 Packages which need a single statically allocated
5180 uid or gid should use one of these; their
5181 maintainers should ask the <tt>base-passwd</tt>
5189 Dynamically allocated system users and groups.
5190 Packages which need a user or group, but can have
5191 this user or group allocated dynamically and
5192 differently on each system, should use <tt>adduser
5193 --system</tt> to create the group and/or user.
5194 <prgn>adduser</prgn> will check for the existence of
5195 the user or group, and if necessary choose an unused
5196 id based on the ranges specified in
5197 <file>adduser.conf</file>.
5201 <tag>1000-29999:</tag>
5204 Dynamically allocated user accounts. By default
5205 <prgn>adduser</prgn> will choose UIDs and GIDs for
5206 user accounts in this range, though
5207 <file>adduser.conf</file> may be used to modify this
5212 <tag>30000-59999:</tag>
5217 <tag>60000-64999:</tag>
5220 Globally allocated by the Debian project, but only
5221 created on demand. The ids are allocated centrally
5222 and statically, but the actual accounts are only
5223 created on users' systems on demand.
5227 These ids are for packages which are obscure or
5228 which require many statically-allocated ids. These
5229 packages should check for and create the accounts in
5230 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5231 <prgn>adduser</prgn> if it has this facility) if
5232 necessary. Packages which are likely to require
5233 further allocations should have a "hole" left after
5234 them in the allocation, to give them room to
5239 <tag>65000-65533:</tag>
5247 User <tt>nobody</tt>. The corresponding gid refers
5248 to the group <tt>nogroup</tt>.
5255 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5256 not</em> be used, because it is the error return
5265 <sect id="sysvinit">
5266 <heading>System run levels and <file>init.d</file> scripts</heading>
5268 <sect1 id="/etc/init.d">
5269 <heading>Introduction</heading>
5272 The <file>/etc/init.d</file> directory contains the scripts
5273 executed by <prgn>init</prgn> at boot time and when the
5274 init state (or "runlevel") is changed (see <manref
5275 name="init" section="8">).
5279 There are at least two different, yet functionally
5280 equivalent, ways of handling these scripts. For the sake
5281 of simplicity, this document describes only the symbolic
5282 link method. However, it must not be assumed by maintainer
5283 scripts that this method is being used, and any automated
5284 manipulation of the various runlevel behaviours by
5285 maintainer scripts must be performed using
5286 <prgn>update-rc.d</prgn> as described below and not by
5287 manually installing or removing symlinks. For information
5288 on the implementation details of the other method,
5289 implemented in the <tt>file-rc</tt> package, please refer
5290 to the documentation of that package.
5294 These scripts are referenced by symbolic links in the
5295 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5296 runlevels, <prgn>init</prgn> looks in the directory
5297 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5298 execute, where <tt><var>n</var></tt> is the runlevel that
5299 is being changed to, or <tt>S</tt> for the boot-up
5304 The names of the links all have the form
5305 <file>S<var>mm</var><var>script</var></file> or
5306 <file>K<var>mm</var><var>script</var></file> where
5307 <var>mm</var> is a two-digit number and <var>script</var>
5308 is the name of the script (this should be the same as the
5309 name of the actual script in <file>/etc/init.d</file>).
5313 When <prgn>init</prgn> changes runlevel first the targets
5314 of the links whose names start with a <tt>K</tt> are
5315 executed, each with the single argument <tt>stop</tt>,
5316 followed by the scripts prefixed with an <tt>S</tt>, each
5317 with the single argument <tt>start</tt>. (The links are
5318 those in the <file>/etc/rc<var>n</var>.d</file> directory
5319 corresponding to the new runlevel.) The <tt>K</tt> links
5320 are responsible for killing services and the <tt>S</tt>
5321 link for starting services upon entering the runlevel.
5325 For example, if we are changing from runlevel 2 to
5326 runlevel 3, init will first execute all of the <tt>K</tt>
5327 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5328 all of the <tt>S</tt> prefixed scripts in that directory.
5329 The links starting with <tt>K</tt> will cause the
5330 referred-to file to be executed with an argument of
5331 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5336 The two-digit number <var>mm</var> is used to determine
5337 the order in which to run the scripts: low-numbered links
5338 have their scripts run first. For example, the
5339 <tt>K20</tt> scripts will be executed before the
5340 <tt>K30</tt> scripts. This is used when a certain service
5341 must be started before another. For example, the name
5342 server <prgn>bind</prgn> might need to be started before
5343 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5344 can set up its access lists. In this case, the script
5345 that starts <prgn>bind</prgn> would have a lower number
5346 than the script that starts <prgn>inn</prgn> so that it
5348 <example compact="compact">
5355 The two runlevels 0 (halt) and 6 (reboot) are slightly
5356 different. In these runlevels, the links with an
5357 <tt>S</tt> prefix are still called after those with a
5358 <tt>K</tt> prefix, but they too are called with the single
5359 argument <tt>stop</tt>.
5363 Also, if the script name ends <tt>.sh</tt>, the script
5364 will be sourced in runlevel <tt>S</tt> rather that being
5365 run in a forked subprocess, but will be explicitly run by
5366 <prgn>sh</prgn> in all other runlevels.
5371 <heading>Writing the scripts</heading>
5374 Packages that include daemons for system services should
5375 place scripts in <file>/etc/init.d</file> to start or stop
5376 services at boot time or during a change of runlevel.
5377 These scripts should be named
5378 <file>/etc/init.d/<var>package</var></file>, and they should
5379 accept one argument, saying what to do:
5382 <tag><tt>start</tt></tag>
5383 <item>start the service,</item>
5385 <tag><tt>stop</tt></tag>
5386 <item>stop the service,</item>
5388 <tag><tt>restart</tt></tag>
5389 <item>stop and restart the service if it's already running,
5390 otherwise start the service</item>
5392 <tag><tt>reload</tt></tag>
5393 <item><p>cause the configuration of the service to be
5394 reloaded without actually stopping and restarting
5397 <tag><tt>force-reload</tt></tag>
5398 <item>cause the configuration to be reloaded if the
5399 service supports this, otherwise restart the
5403 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5404 <tt>force-reload</tt> options should be supported by all
5405 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5410 The <file>init.d</file> scripts should ensure that they will
5411 behave sensibly if invoked with <tt>start</tt> when the
5412 service is already running, or with <tt>stop</tt> when it
5413 isn't, and that they don't kill unfortunately-named user
5414 processes. The best way to achieve this is usually to use
5415 <prgn>start-stop-daemon</prgn>.
5419 If a service reloads its configuration automatically (as
5420 in the case of <prgn>cron</prgn>, for example), the
5421 <tt>reload</tt> option of the <file>init.d</file> script
5422 should behave as if the configuration has been reloaded
5427 The <file>/etc/init.d</file> scripts must be treated as
5428 configuration files, either (if they are present in the
5429 package, that is, in the .deb file) by marking them as
5430 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5431 by managing them correctly in the maintainer scripts (see
5432 <ref id="config-files">). This is important since we want
5433 to give the local system administrator the chance to adapt
5434 the scripts to the local system, e.g., to disable a
5435 service without de-installing the package, or to specify
5436 some special command line options when starting a service,
5437 while making sure her changes aren't lost during the next
5442 These scripts should not fail obscurely when the
5443 configuration files remain but the package has been
5444 removed, as configuration files remain on the system after
5445 the package has been removed. Only when <prgn>dpkg</prgn>
5446 is executed with the <tt>--purge</tt> option will
5447 configuration files be removed. In particular, as the
5448 <file>/etc/init.d/<var>package</var></file> script itself is
5449 usually a <tt>conffile</tt>, it will remain on the system
5450 if the package is removed but not purged. Therefore, you
5451 should include a <tt>test</tt> statement at the top of the
5453 <example compact="compact">
5454 test -f <var>program-executed-later-in-script</var> || exit 0
5459 Often there are some variables in the <file>init.d</file>
5460 scripts whose values control the behaviour of the scripts,
5461 and which a system administrator is likely to want to
5462 change. As the scripts themselves are frequently
5463 <tt>conffile</tt>s, modifying them requires that the
5464 administrator merge in their changes each time the package
5465 is upgraded and the <tt>conffile</tt> changes. To ease
5466 the burden on the system administrator, such configurable
5467 values should not be placed directly in the script.
5468 Instead, they should be placed in a file in
5469 <file>/etc/default</file>, which typically will have the same
5470 base name as the <file>init.d</file> script. This extra file
5471 should be sourced by the script when the script runs. It
5472 must contain only variable settings and comments in POSIX
5473 <prgn>sh</prgn> format. It may either be a
5474 <tt>conffile</tt> or a configuration file maintained by
5475 the package maintainer scripts. See <ref id="config-files">
5480 To ensure that vital configurable values are always
5481 available, the <file>init.d</file> script should set default
5482 values for each of the shell variables it uses, either
5483 before sourcing the <file>/etc/default/</file> file or
5484 afterwards using something like the <tt>:
5485 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5486 script must behave sensibly and not fail if the
5487 <file>/etc/default</file> file is deleted.
5492 <heading>Interfacing with the initscript system</heading>
5495 Maintainers should use the abstraction layer provided by
5496 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5497 programs to deal with initscripts in their packages'
5498 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5499 and <prgn>postrm</prgn>.
5503 Directly managing the /etc/rc?.d links and directly
5504 invoking the <file>/etc/init.d/</file> initscripts should
5505 be done only by packages providing the initscript
5506 subsystem (such as <prgn>sysv-rc</prgn> and
5507 <prgn>file-rc</prgn>).
5511 <heading>Managing the links</heading>
5514 The program <prgn>update-rc.d</prgn> is provided for
5515 package maintainers to arrange for the proper creation and
5516 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5517 or their functional equivalent if another method is being
5518 used. This may be used by maintainers in their packages'
5519 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5523 You must not include any <file>/etc/rc<var>n</var>.d</file>
5524 symbolic links in the actual archive or manually create or
5525 remove the symbolic links in maintainer scripts; you must
5526 use the <prgn>update-rc.d</prgn> program instead. (The
5527 former will fail if an alternative method of maintaining
5528 runlevel information is being used.) You must not include
5529 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5530 in the archive either. (Only the <tt>sysvinit</tt>
5535 By default <prgn>update-rc.d</prgn> will start services in
5536 each of the multi-user state runlevels (2, 3, 4, and 5)
5537 and stop them in the halt runlevel (0), the single-user
5538 runlevel (1) and the reboot runlevel (6). The system
5539 administrator will have the opportunity to customize
5540 runlevels by simply adding, moving, or removing the
5541 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5542 symbolic links are being used, or by modifying
5543 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5548 To get the default behavior for your package, put in your
5549 <prgn>postinst</prgn> script
5550 <example compact="compact">
5551 update-rc.d <var>package</var> defaults
5553 and in your <prgn>postrm</prgn>
5554 <example compact="compact">
5555 if [ "$1" = purge ]; then
5556 update-rc.d <var>package</var> remove
5558 </example>. Note that if your package changes runlevels
5559 or priority, you may have to remove and recreate the links,
5560 since otherwise the old links may persist. Refer to the
5561 documentation of <prgn>update-rc.d</prgn>.
5565 This will use a default sequence number of 20. If it does
5566 not matter when or in which order the <file>init.d</file>
5567 script is run, use this default. If it does, then you
5568 should talk to the maintainer of the <prgn>sysvinit</prgn>
5569 package or post to <tt>debian-devel</tt>, and they will
5570 help you choose a number.
5574 For more information about using <tt>update-rc.d</tt>,
5575 please consult its manpage <manref name="update-rc.d"
5581 <heading>Running initscripts</heading>
5583 The program <prgn>invoke-rc.d</prgn> is provided to make
5584 it easier for package maintainers to properly invoke an
5585 initscript, obeying runlevel and other locally-defined
5586 constraints that might limit a package's right to start,
5587 stop and otherwise manage services. This program may be
5588 used by maintainers in their packages' scripts.
5592 The use of <prgn>invoke-rc.d</prgn> to invoke the
5593 <file>/etc/init.d/*</file> initscripts is strongly
5594 recommended<footnote>
5595 In the future, the use of invoke-rc.d to invoke
5596 initscripts shall be made mandatory. Maintainers are
5597 advised to switch to invoke-rc.d as soon as
5599 </footnote>, instead of calling them directly.
5603 By default, <prgn>invoke-rc.d</prgn> will pass any
5604 action requests (start, stop, reload, restart...) to the
5605 <file>/etc/init.d</file> script, filtering out requests
5606 to start or restart a service out of its intended
5611 Most packages will simply need to change:
5612 <example compact="compact">/etc/init.d/<package>
5613 <action></example> in their <prgn>postinst</prgn>
5614 and <prgn>prerm</prgn> scripts to:
5615 <example compact="compact">
5616 if command -v invoke-rc.d >/dev/null 2>&1; then
5617 invoke-rc.d <var>package</var> <action>
5619 /etc/init.d/<var>package</var> <action>
5625 A package should register its initscript services using
5626 <prgn>update-rc.d</prgn> before it tries to invoke them
5627 using <prgn>invoke-rc.d</prgn>. Invocation of
5628 unregistered services may fail.
5632 For more information about using
5633 <prgn>invoke-rc.d</prgn>, please consult its manpage
5634 <manref name="invoke-rc.d" section="8">.
5640 <heading>Boot-time initialization</heading>
5643 There used to be another directory, <file>/etc/rc.boot</file>,
5644 which contained scripts which were run once per machine
5645 boot. This has been deprecated in favour of links from
5646 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5647 described in <ref id="/etc/init.d">. Packages must not
5648 place files in <file>/etc/rc.boot</file>.
5653 <heading>Example</heading>
5656 The <prgn>bind</prgn> DNS (nameserver) package wants to
5657 make sure that the nameserver is running in multiuser
5658 runlevels, and is properly shut down with the system. It
5659 puts a script in <file>/etc/init.d</file>, naming the script
5660 appropriately <tt>bind</tt>. As you can see, the script
5661 interprets the argument <tt>reload</tt> to send the
5662 nameserver a <tt>HUP</tt> signal (causing it to reload its
5663 configuration); this way the system administrator can say
5664 <tt>/etc/init.d/bind reload</tt> to reload the name
5665 server. The script has one configurable value, which can
5666 be used to pass parameters to the named program at
5667 startup; this value is read from
5668 <file>/etc/default/bind</file> (see below).
5672 <example compact="compact">
5675 # Original version by Robert Leslie
5676 # <rob@mars.org>, edited by iwj and cs
5678 test -x /usr/sbin/named || exit 0
5680 # Source defaults file.
5682 if [ -f /etc/default/bind ]; then
5689 echo -n "Starting domain name service: named"
5690 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5695 echo -n "Stopping domain name service: named"
5696 start-stop-daemon --stop --quiet \
5697 --pidfile /var/run/named.pid --exec /usr/sbin/named
5701 echo -n "Restarting domain name service: named"
5702 start-stop-daemon --stop --quiet --oknodo \
5703 --pidfile /var/run/named.pid --exec /usr/sbin/named
5704 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5708 force-reload|reload)
5709 echo -n "Reloading configuration of domain name service: named"
5710 start-stop-daemon --stop --signal 1 --quiet \
5711 --pidfile /var/run/named.pid --exec /usr/sbin/named
5715 echo "Usage: /etc/init.d/bind " \
5716 " {start|stop|restart|reload|force-reload}" >&2
5726 Complementing the above init script is a configuration
5727 file <file>/etc/default/bind</file>, which contains
5728 configurable parameters used by the script. This would be
5729 created by the <prgn>postinst</prgn> script if it was not
5730 already present, and removed on purge by the
5731 <prgn>postrm</prgn> script.
5732 <example compact="compact">
5733 # Specified parameters to pass to named. See named(8).
5734 # You may uncomment the following line, and edit to taste.
5740 Another example on which you can base your
5741 <file>/etc/init.d</file> scripts is found in
5742 <file>/etc/init.d/skeleton</file>.
5746 If this package is happy with the default setup from
5747 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5748 and having named running in all runlevels, it can say in
5749 its <prgn>postinst</prgn>:
5750 <example compact="compact">
5751 update-rc.d bind defaults >/dev/null
5753 And in its <prgn>postrm</prgn>, to remove the links when the
5755 <example compact="compact">
5756 if [ "$1" = purge ]; then
5757 update-rc.d bind remove >/dev/null
5765 <heading>Console messages from <file>init.d</file> scripts</heading>
5768 This section describes the formats to be used for messages
5769 written to standard output by the <file>/etc/init.d</file>
5770 scripts. The intent is to improve the consistency of
5771 Debian's startup and shutdown look and feel. For this
5772 reason, please look very carefully at the details. We want
5773 the messages to have the same format in terms of wording,
5774 spaces, punctuation and case of letters.
5778 Here is a list of overall rules that you should use when you
5779 create output messages. They can be useful if you have a
5780 non-standard message that is not covered specifically in the
5787 Every message should fit in one line (fewer than 80
5788 characters), start with a capital letter and end with
5789 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5793 If you want to express that the computer is working on
5794 something (that is, performing a specific task, not
5795 starting or stopping a program), we use an "ellipsis"
5796 (three dots: <tt>...</tt>). Note that we don't insert
5797 spaces before or after the dots. If the task has been
5798 completed we write <tt>done.</tt> and a line feed.
5802 Design your messages as if the computer is telling you
5803 what he is doing (let him be polite :-), but don't
5804 mention "him" directly. For example, if you think of
5806 <example compact="compact">
5807 I'm starting network daemons: nfsd mountd.
5810 <example compact="compact">
5811 Starting network daemons: nfsd mountd.
5818 There are standard message formats for the following
5819 situations. They should be used by the <tt>init.d</tt>
5826 <p>When daemons are started</p>
5829 If your script starts one or more daemons, the output
5830 should look like this (a single line, no leading
5832 <example compact="compact">
5833 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5835 The <var>description</var> should describe the
5836 subsystem the daemon or set of daemons are part of,
5837 while <var>daemon-1</var> up to <var>daemon-n</var>
5838 denote each daemon's name (typically the file name of
5843 For example, the output of <file>/etc/init.d/lpd</file>
5845 <example compact="compact">
5846 Starting printer spooler: lpd.
5851 This can be achieved by saying
5852 <example compact="compact">
5853 echo -n "Starting printer spooler: lpd"
5854 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5857 in the script. If you have more than one daemon to
5858 start, you should do the following:
5859 <example compact="compact">
5860 echo -n "Starting remote file system services:"
5861 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5862 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5863 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5866 This makes it possible for the user to see what takes
5867 so long and when the final daemon has been started.
5868 You should be careful where to put spaces: in the
5869 example above the system administrator can easily
5870 comment out a line if he don't wants to start a
5871 specific daemon, while the displayed message still
5877 <p>When a system parameter is being set</p>
5880 If you have to set up different system parameters
5881 during the system boot, you should use this format:
5882 <example compact="compact">
5883 Setting <var>parameter</var> to "<var>value</var>".
5888 You can use a statement such as the following to get
5890 <example compact="compact">
5891 echo "Setting DNS domainname to \"$domainname\"."
5896 Note that the same symbol (<tt>"</tt>) is used for the left
5897 and right quotation marks. A grave accent (<tt>`</tt>) is
5898 not a quote character; neither is an apostrophe
5904 <p>When a daemon is stopped or restarted</p>
5907 When you stop or restart a daemon, you should issue a
5908 message identical to the startup message, except that
5909 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5910 or <tt>Restarting</tt> respectively.
5914 For example, stopping the printer daemon will like
5916 <example compact="compact">
5917 Stopping printer spooler: lpd.
5923 <p>When something is executed</p>
5926 There are several examples where you have to run a
5927 program at system startup or shutdown to perform a
5928 specific task, for example, setting the system's clock
5929 using <prgn>netdate</prgn> or killing all processes
5930 when the system shuts down. Your message should look
5932 <example compact="compact">
5933 Doing something very useful...done.
5935 You should print the <tt>done.</tt> immediately after
5936 the job has been completed, so that the user is
5937 informed why she has to wait. You can get this
5939 <example compact="compact">
5940 echo -n "Doing something very useful..."
5949 <p>When the configuration is reloaded</p>
5952 When a daemon is forced to reload its configuration
5953 files you should use the following format:
5954 <example compact="compact">
5955 Reloading <var>description</var> configuration...done.
5957 where <var>description</var> is the same as in the
5958 daemon starting message.
5966 <heading>Cron jobs</heading>
5969 Packages must not modify the configuration file
5970 <file>/etc/crontab</file>, and they must not modify the files in
5971 <file>/var/spool/cron/crontabs</file>.</p>
5974 If a package wants to install a job that has to be executed
5975 via cron, it should place a file with the name of the
5976 package in one or more of the following directories:
5977 <example compact="compact">
5982 As these directory names imply, the files within them are
5983 executed on a daily, weekly, or monthly basis,
5984 respectively. The exact times are listed in
5985 <file>/etc/crontab</file>.</p>
5988 All files installed in any of these directories must be
5989 scripts (e.g., shell scripts or Perl scripts) so that they
5990 can easily be modified by the local system administrator.
5991 In addition, they should be treated as configuration
5996 If a certain job has to be executed more frequently than
5997 daily, the package should install a file
5998 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5999 same syntax as <file>/etc/crontab</file> and is processed by
6000 <prgn>cron</prgn> automatically. The file must also be
6001 treated as a configuration file. (Note that entries in the
6002 <file>/etc/cron.d</file> directory are not handled by
6003 <prgn>anacron</prgn>. Thus, you should only use this
6004 directory for jobs which may be skipped if the system is not
6008 The scripts or crontab entries in these directories should
6009 check if all necessary programs are installed before they
6010 try to execute them. Otherwise, problems will arise when a
6011 package was removed but not purged since configuration files
6012 are kept on the system in this situation.</p>
6016 <heading>Menus</heading>
6019 The Debian <tt>menu</tt> package provides a standard
6020 interface between packages providing applications and
6021 documents, and <em>menu programs</em> (either X window
6022 managers or text-based menu programs such as
6023 <prgn>pdmenu</prgn>).
6027 All packages that provide applications that need not be
6028 passed any special command line arguments for normal
6029 operation should register a menu entry for those
6030 applications, so that users of the <tt>menu</tt> package
6031 will automatically get menu entries in their window
6032 managers, as well in shells like <tt>pdmenu</tt>.
6036 Menu entries should follow the current menu policy.
6040 The menu policy can be found in the <tt>menu-policy</tt>
6041 files in the <tt>debian-policy</tt> package.
6042 It is also available from the Debian web mirrors at
6043 <tt><url name="/doc/packaging-manuals/menu-policy/"
6044 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
6045 and from the Debian archive mirrors at
6046 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
6047 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
6051 Please also refer to the <em>Debian Menu System</em>
6052 documentation that comes with the <tt>menu</tt> package for
6053 information about how to register your applications and web
6059 <heading>Multimedia handlers</heading>
6062 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6063 is a mechanism for encoding files and data streams and
6064 providing meta-information about them, in particular their
6065 type (e.g. audio or video) and format (e.g. PNG, HTML,
6070 Registration of MIME type handlers allows programs like mail
6071 user agents and web browsers to invoke these handlers to
6072 view, edit or display MIME types they don't support directly.
6076 Packages which provide the ability to view/show/play,
6077 compose, edit or print MIME types should register themselves
6078 as such following the current MIME support policy.
6082 The MIME support policy can be found in the <tt>mime-policy</tt>
6083 files in the <tt>debian-policy</tt> package.
6084 It is also available from the Debian web mirrors at
6085 <tt><url name="/doc/packaging-manuals/mime-policy/"
6086 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
6087 and from the Debian archive mirrors at
6088 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
6089 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
6095 <heading>Keyboard configuration</heading>
6098 To achieve a consistent keyboard configuration so that all
6099 applications interpret a keyboard event the same way, all
6100 programs in the Debian distribution must be configured to
6101 comply with the following guidelines.
6105 The following keys must have the specified interpretations:
6108 <tag><tt><--</tt></tag>
6109 <item>delete the character to the left of the cursor</item>
6111 <tag><tt>Delete</tt></tag>
6112 <item>delete the character to the right of the cursor</item>
6114 <tag><tt>Control+H</tt></tag>
6115 <item>emacs: the help prefix</item>
6118 The interpretation of any keyboard events should be
6119 independent of the terminal that is used, be it a virtual
6120 console, an X terminal emulator, an rlogin/telnet session,
6125 The following list explains how the different programs
6126 should be set up to achieve this:
6132 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6136 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6140 X translations are set up to make
6141 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6142 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6143 is the vt220 escape code for the "delete character"
6144 key). This must be done by loading the X resources
6145 using <prgn>xrdb</prgn> on all local X displays, not
6146 using the application defaults, so that the
6147 translation resources used correspond to the
6148 <prgn>xmodmap</prgn> settings.
6152 The Linux console is configured to make
6153 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6154 generate <tt>ESC [ 3 ~</tt>.
6158 X applications are configured so that <tt><</tt>
6159 deletes left, and <tt>Delete</tt> deletes right. Motif
6160 applications already work like this.
6164 Terminals should have <tt>stty erase ^?</tt> .
6168 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6169 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6170 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6174 Emacs is programmed to map <tt>KB_Backspace</tt> or
6175 the <tt>stty erase</tt> character to
6176 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6177 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6178 <tt>^H</tt> to <tt>help</tt> as always.
6182 Other applications use the <tt>stty erase</tt>
6183 character and <tt>kdch1</tt> for the two delete keys,
6184 with ASCII DEL being "delete previous character" and
6185 <tt>kdch1</tt> being "delete character under
6193 This will solve the problem except for the following
6200 Some terminals have a <tt><--</tt> key that cannot
6201 be made to produce anything except <tt>^H</tt>. On
6202 these terminals Emacs help will be unavailable on
6203 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6204 character takes precedence in Emacs, and has been set
6205 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6206 available) can be used instead.
6210 Some operating systems use <tt>^H</tt> for <tt>stty
6211 erase</tt>. However, modern telnet versions and all
6212 rlogin versions propagate <tt>stty</tt> settings, and
6213 almost all UNIX versions honour <tt>stty erase</tt>.
6214 Where the <tt>stty</tt> settings are not propagated
6215 correctly, things can be made to work by using
6216 <tt>stty</tt> manually.
6220 Some systems (including previous Debian versions) use
6221 <prgn>xmodmap</prgn> to arrange for both
6222 <tt><--</tt> and <tt>Delete</tt> to generate
6223 <tt>KB_Delete</tt>. We can change the behavior of
6224 their X clients using the same X resources that we use
6225 to do it for our own clients, or configure our clients
6226 using their resources when things are the other way
6227 around. On displays configured like this
6228 <tt>Delete</tt> will not work, but <tt><--</tt>
6233 Some operating systems have different <tt>kdch1</tt>
6234 settings in their <tt>terminfo</tt> database for
6235 <tt>xterm</tt> and others. On these systems the
6236 <tt>Delete</tt> key will not work correctly when you
6237 log in from a system conforming to our policy, but
6238 <tt><--</tt> will.
6245 <heading>Environment variables</heading>
6248 A program must not depend on environment variables to get
6249 reasonable defaults. (That's because these environment
6250 variables would have to be set in a system-wide
6251 configuration file like <file>/etc/profile</file>, which is not
6252 supported by all shells.)
6256 If a program usually depends on environment variables for its
6257 configuration, the program should be changed to fall back to
6258 a reasonable default configuration if these environment
6259 variables are not present. If this cannot be done easily
6260 (e.g., if the source code of a non-free program is not
6261 available), the program must be replaced by a small
6262 "wrapper" shell script which sets the environment variables
6263 if they are not already defined, and calls the original program.
6267 Here is an example of a wrapper script for this purpose:
6269 <example compact="compact">
6271 BAR=${BAR:-/var/lib/fubar}
6273 exec /usr/lib/foo/foo "$@"
6278 Furthermore, as <file>/etc/profile</file> is a configuration
6279 file of the <prgn>base-files</prgn> package, other packages must
6280 not put any environment variables or other commands into that
6289 <heading>Files</heading>
6292 <heading>Binaries</heading>
6295 Two different packages must not install programs with
6296 different functionality but with the same filenames. (The
6297 case of two programs having the same functionality but
6298 different implementations is handled via "alternatives" or
6299 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6300 <ref id="conflicts"> respectively.) If this case happens,
6301 one of the programs must be renamed. The maintainers should
6302 report this to the <tt>debian-devel</tt> mailing list and
6303 try to find a consensus about which program will have to be
6304 renamed. If a consensus cannot be reached, <em>both</em>
6305 programs must be renamed.
6309 By default, when a package is being built, any binaries
6310 created should include debugging information, as well as
6311 being compiled with optimization. You should also turn on
6312 as many reasonable compilation warnings as possible; this
6313 makes life easier for porters, who can then look at build
6314 logs for possible problems. For the C programming language,
6315 this means the following compilation parameters should be
6317 <example compact="compact">
6319 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6321 install -s # (or use strip on the files in debian/tmp)
6326 Note that by default all installed binaries should be stripped,
6327 either by using the <tt>-s</tt> flag to
6328 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6329 the binaries after they have been copied into
6330 <file>debian/tmp</file> but before the tree is made into a
6335 Although binaries in the build tree should be compiled with
6336 debugging information by default, it can often be difficult
6337 to debug programs if they are also subjected to compiler
6338 optimization. For this reason, it is recommended to support
6339 the standardized environment
6340 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6341 contain several flags to change how a package is compiled
6349 The presence of this string means that the package
6350 should be compiled with a minimum of optimization.
6351 For C programs, it is best to add <tt>-O0</tt>
6352 to <tt>CFLAGS</tt> (although this is usually the
6353 default). Some programs might fail to build or run at
6354 this level of optimization; it may be necessary to
6355 use <tt>-O1</tt>, for example.
6359 This string means that the debugging symbols should
6360 not be stripped from the binary during installation,
6361 so that debugging information may be included in the package.
6367 The following makefile snippet is an example of how one may
6368 implement the build options; you will probably have to
6369 massage this example in order to make it work for your
6371 <example compact="compact">
6374 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6375 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6376 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6377 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6379 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6384 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6385 INSTALL_PROGRAM += -s
6391 It is up to the package maintainer to decide what
6392 compilation options are best for the package. Certain
6393 binaries (such as computationally-intensive programs) will
6394 function better with certain flags (<tt>-O3</tt>, for
6395 example); feel free to use them. Please use good judgment
6396 here. Don't use flags for the sake of it; only use them
6397 if there is good reason to do so. Feel free to override
6398 the upstream author's ideas about which compilation
6399 options are best: they are often inappropriate for our
6405 <sect id="libraries">
6406 <heading>Libraries</heading>
6409 The shared version of a library must be compiled with
6410 <tt>-fPIC</tt>, and the static version must not be. In other
6411 words, each source unit (<tt>*.c</tt>, for example, for C files)
6412 will need to be compiled twice.
6416 You must specify the gcc option <tt>-D_REENTRANT</tt>
6417 when building a library (either static or shared) to make
6418 the library compatible with LinuxThreads.
6422 Although not enforced by the build tools, shared libraries
6423 must be linked against all libraries that they use symbols from
6424 in the same way that binaries are. This ensures the correct
6425 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6426 system and guarantees that all libraries can be safely opened
6427 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6428 option <tt>-Wl,-z,defs</tt> when building a shared library.
6429 Since this option enforces symbol resolution at build time,
6430 a missing library reference will be caught early as a fatal
6435 All installed shared libraries should be stripped with
6436 <example compact="compact">
6437 strip --strip-unneeded <var>your-lib</var>
6439 (The option <tt>--strip-unneeded</tt> makes
6440 <prgn>strip</prgn> remove only the symbols which aren't
6441 needed for relocation processing.) Shared libraries can
6442 function perfectly well when stripped, since the symbols for
6443 dynamic linking are in a separate part of the ELF object
6445 You might also want to use the options
6446 <tt>--remove-section=.comment</tt> and
6447 <tt>--remove-section=.note</tt> on both shared libraries
6448 and executables, and <tt>--strip-debug</tt> on static
6454 Note that under some circumstances it may be useful to
6455 install a shared library unstripped, for example when
6456 building a separate package to support debugging.
6460 Shared object files (often <file>.so</file> files) that are not
6461 public libraries, that is, they are not meant to be linked
6462 to by third party executables (binaries of other packages),
6463 should be installed in subdirectories of the
6464 <file>/usr/lib</file> directory. Such files are exempt from the
6465 rules that govern ordinary shared libraries, except that
6466 they must not be installed executable and should be
6468 A common example are the so-called "plug-ins",
6469 internal shared objects that are dynamically loaded by
6470 programs using <manref name="dlopen" section="3">.
6475 Packages containing shared libraries that may be linked to
6476 by other packages' binaries, but which for some
6477 <em>compelling</em> reason can not be installed in
6478 <file>/usr/lib</file> directory, may install the shared library
6479 files in subdirectories of the <file>/usr/lib</file> directory,
6480 in which case they should arrange to add that directory in
6481 <file>/etc/ld.so.conf</file> in the package's post-installation
6482 script, and remove it in the package's post-removal script.
6486 An ever increasing number of packages are using
6487 <prgn>libtool</prgn> to do their linking. The latest GNU
6488 libtools (>= 1.3a) can take advantage of the metadata in the
6489 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6490 files). The main advantage of <prgn>libtool</prgn>'s
6491 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6492 store and subsequently access metadata with respect to the
6493 libraries it builds. <prgn>libtool</prgn> will search for
6494 those files, which contain a lot of useful information about
6495 a library (such as library dependency information for static
6496 linking). Also, they're <em>essential</em> for programs
6497 using <tt>libltdl</tt>.<footnote>
6498 Although <prgn>libtool</prgn> is fully capable of
6499 linking against shared libraries which don't have
6500 <tt>.la</tt> files, as it is a mere shell script it can
6501 add considerably to the build time of a
6502 <prgn>libtool</prgn>-using package if that shell script
6503 has to derive all this information from first principles
6504 for each library every time it is linked. With the
6505 advent of <prgn>libtool</prgn> version 1.4 (and to a
6506 lesser extent <prgn>libtool</prgn> version 1.3), the
6507 <file>.la</file> files also store information about
6508 inter-library dependencies which cannot necessarily be
6509 derived after the <file>.la</file> file is deleted.
6514 Packages that use <prgn>libtool</prgn> to create shared
6515 libraries should include the <file>.la</file> files in the
6516 <tt>-dev</tt> package, unless the package relies on
6517 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6518 the <tt>.la</tt> files must go in the run-time library
6523 You must make sure that you use only released versions of
6524 shared libraries to build your packages; otherwise other
6525 users will not be able to run your binaries
6526 properly. Producing source packages that depend on
6527 unreleased compilers is also usually a bad
6534 <heading>Shared libraries</heading>
6536 This section has moved to <ref id="sharedlibs">.
6542 <heading>Scripts</heading>
6545 All command scripts, including the package maintainer
6546 scripts inside the package and used by <prgn>dpkg</prgn>,
6547 should have a <tt>#!</tt> line naming the shell to be used
6552 In the case of Perl scripts this should be
6553 <tt>#!/usr/bin/perl</tt>.
6557 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6558 should almost certainly start with <tt>set -e</tt> so that
6559 errors are detected. Every script should use
6560 <tt>set -e</tt> or check the exit status of <em>every</em>
6565 The standard shell interpreter <file>/bin/sh</file> can be a
6566 symbolic link to any POSIX compatible shell, if <tt>echo
6567 -n</tt> does not generate a newline.<footnote>
6568 Debian policy specifies POSIX behavior for
6569 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6570 use in the Linux community (in particular including this
6571 policy, the Linux kernel source, many Debian scripts,
6572 etc.). This <tt>echo -n</tt> mechanism is valid but not
6573 required under POSIX, hence this explicit addition.
6574 Also, rumour has it that this shall be mandated under
6577 Thus, shell scripts specifying <file>/bin/sh</file> as
6578 interpreter should only use POSIX features. If a script
6579 requires non-POSIX features from the shell interpreter, the
6580 appropriate shell must be specified in the first line of the
6581 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6582 depend on the package providing the shell (unless the shell
6583 package is marked "Essential", as in the case of
6588 You may wish to restrict your script to POSIX features when
6589 possible so that it may use <file>/bin/sh</file> as its
6590 interpreter. If your script works with <prgn>dash</prgn>
6591 (originally called <prgn>ash</prgn>), it's probably POSIX
6592 compliant, but if you are in doubt, use
6593 <file>/bin/bash</file>.
6597 Perl scripts should check for errors when making any
6598 system calls, including <tt>open</tt>, <tt>print</tt>,
6599 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6603 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6604 scripting languages. See <em>Csh Programming Considered
6605 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6606 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
6607 If an upstream package comes with <prgn>csh</prgn> scripts
6608 then you must make sure that they start with
6609 <tt>#!/bin/csh</tt> and make your package depend on the
6610 <prgn>c-shell</prgn> virtual package.
6614 Any scripts which create files in world-writeable
6615 directories (e.g., in <file>/tmp</file>) must use a
6616 mechanism which will fail if a file with the same name
6621 The Debian base system provides the <prgn>tempfile</prgn>
6622 and <prgn>mktemp</prgn> utilities for use by scripts for
6629 <heading>Symbolic links</heading>
6632 In general, symbolic links within a top-level directory
6633 should be relative, and symbolic links pointing from one
6634 top-level directory into another should be absolute. (A
6635 top-level directory is a sub-directory of the root
6636 directory <file>/</file>.)
6640 In addition, symbolic links should be specified as short as
6641 possible, i.e., link targets like <file>foo/../bar</file> are
6646 Note that when creating a relative link using
6647 <prgn>ln</prgn> it is not necessary for the target of the
6648 link to exist relative to the working directory you're
6649 running <prgn>ln</prgn> from, nor is it necessary to change
6650 directory to the directory where the link is to be made.
6651 Simply include the string that should appear as the target
6652 of the link (this will be a pathname relative to the
6653 directory in which the link resides) as the first argument
6658 For example, in your <prgn>Makefile</prgn> or
6659 <file>debian/rules</file>, you can do things like:
6660 <example compact="compact">
6661 ln -fs gcc $(prefix)/bin/cc
6662 ln -fs gcc debian/tmp/usr/bin/cc
6663 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6664 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6669 A symbolic link pointing to a compressed file should always
6670 have the same file extension as the referenced file. (For
6671 example, if a file <file>foo.gz</file> is referenced by a
6672 symbolic link, the filename of the link has to end with
6673 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6678 <heading>Device files</heading>
6681 Packages must not include device files in the package file
6686 If a package needs any special device files that are not
6687 included in the base system, it must call
6688 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6689 after notifying the user<footnote>
6690 This notification could be done via a (low-priority)
6691 debconf message, or an echo (printf) statement.
6696 Packages must not remove any device files in the
6697 <prgn>postrm</prgn> or any other script. This is left to the
6698 system administrator.
6702 Debian uses the serial devices
6703 <file>/dev/ttyS*</file>. Programs using the old
6704 <file>/dev/cu*</file> devices should be changed to use
6705 <file>/dev/ttyS*</file>.
6709 <sect id="config-files">
6710 <heading>Configuration files</heading>
6713 <heading>Definitions</heading>
6717 <tag>configuration file</tag>
6719 A file that affects the operation of a program, or
6720 provides site- or host-specific information, or
6721 otherwise customizes the behavior of a program.
6722 Typically, configuration files are intended to be
6723 modified by the system administrator (if needed or
6724 desired) to conform to local policy or to provide
6725 more useful site-specific behavior.
6728 <tag><tt>conffile</tt></tag>
6730 A file listed in a package's <tt>conffiles</tt>
6731 file, and is treated specially by <prgn>dpkg</prgn>
6732 (see <ref id="configdetails">).
6738 The distinction between these two is important; they are
6739 not interchangeable concepts. Almost all
6740 <tt>conffile</tt>s are configuration files, but many
6741 configuration files are not <tt>conffiles</tt>.
6745 Note that a script that embeds configuration information
6746 (such as most of the files in <file>/etc/default</file> and
6747 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6748 configuration file and should be treated as such.
6753 <heading>Location</heading>
6756 Any configuration files created or used by your package
6757 must reside in <file>/etc</file>. If there are several,
6758 consider creating a subdirectory of <file>/etc</file>
6759 named after your package.
6763 If your package creates or uses configuration files
6764 outside of <file>/etc</file>, and it is not feasible to modify
6765 the package to use <file>/etc</file> directly, put the files
6766 in <file>/etc</file> and create symbolic links to those files
6767 from the location that the package requires.
6772 <heading>Behavior</heading>
6775 Configuration file handling must conform to the following
6777 <list compact="compact">
6779 local changes must be preserved during a package
6783 configuration files must be preserved when the
6784 package is removed, and only deleted when the
6791 The easy way to achieve this behavior is to make the
6792 configuration file a <tt>conffile</tt>. This is
6793 appropriate only if it is possible to distribute a default
6794 version that will work for most installations, although
6795 some system administrators may choose to modify it. This
6796 implies that the default version will be part of the
6797 package distribution, and must not be modified by the
6798 maintainer scripts during installation (or at any other
6803 In order to ensure that local changes are preserved
6804 correctly, no package may contain or make hard links to
6805 conffiles.<footnote>
6806 Rationale: There are two problems with hard links.
6807 The first is that some editors break the link while
6808 editing one of the files, so that the two files may
6809 unwittingly become unlinked and different. The second
6810 is that <prgn>dpkg</prgn> might break the hard link
6811 while upgrading <tt>conffile</tt>s.
6816 The other way to do it is via the maintainer scripts. In
6817 this case, the configuration file must not be listed as a
6818 <tt>conffile</tt> and must not be part of the package
6819 distribution. If the existence of a file is required for
6820 the package to be sensibly configured it is the
6821 responsibility of the package maintainer to provide
6822 maintainer scripts which correctly create, update and
6823 maintain the file and remove it on purge. (See <ref
6824 id="maintainerscripts"> for more information.) These
6825 scripts must be idempotent (i.e., must work correctly if
6826 <prgn>dpkg</prgn> needs to re-run them due to errors
6827 during installation or removal), must cope with all the
6828 variety of ways <prgn>dpkg</prgn> can call maintainer
6829 scripts, must not overwrite or otherwise mangle the user's
6830 configuration without asking, must not ask unnecessary
6831 questions (particularly during upgrades), and otherwise be
6836 The scripts are not required to configure every possible
6837 option for the package, but only those necessary to get
6838 the package running on a given system. Ideally the
6839 sysadmin should not have to do any configuration other
6840 than that done (semi-)automatically by the
6841 <prgn>postinst</prgn> script.
6845 A common practice is to create a script called
6846 <file><var>package</var>-configure</file> and have the
6847 package's <prgn>postinst</prgn> call it if and only if the
6848 configuration file does not already exist. In certain
6849 cases it is useful for there to be an example or template
6850 file which the maintainer scripts use. Such files should
6851 be in <file>/usr/share/<var>package</var></file> or
6852 <file>/usr/lib/<var>package</var></file> (depending on whether
6853 they are architecture-independent or not). There should
6854 be symbolic links to them from
6855 <file>/usr/share/doc/<var>package</var>/examples</file> if
6856 they are examples, and should be perfectly ordinary
6857 <prgn>dpkg</prgn>-handled files (<em>not</em>
6858 configuration files).
6862 These two styles of configuration file handling must
6863 not be mixed, for that way lies madness:
6864 <prgn>dpkg</prgn> will ask about overwriting the file
6865 every time the package is upgraded.
6870 <heading>Sharing configuration files</heading>
6873 Packages which specify the same file as a
6874 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6875 with each other. (This is an instance of the general rule
6876 about not sharing files. Note that neither alternatives
6877 nor diversions are likely to be appropriate in this case;
6878 in particular, <prgn>dpkg</prgn> does not handle diverted
6879 <tt>conffile</tt>s well.)
6883 The maintainer scripts must not alter a <tt>conffile</tt>
6884 of <em>any</em> package, including the one the scripts
6889 If two or more packages use the same configuration file
6890 and it is reasonable for both to be installed at the same
6891 time, one of these packages must be defined as
6892 <em>owner</em> of the configuration file, i.e., it will be
6893 the package which handles that file as a configuration
6894 file. Other packages that use the configuration file must
6895 depend on the owning package if they require the
6896 configuration file to operate. If the other package will
6897 use the configuration file if present, but is capable of
6898 operating without it, no dependency need be declared.
6902 If it is desirable for two or more related packages to
6903 share a configuration file <em>and</em> for all of the
6904 related packages to be able to modify that configuration
6905 file, then the following should be done:
6906 <enumlist compact="compact">
6908 One of the related packages (the "owning" package)
6909 will manage the configuration file with maintainer
6910 scripts as described in the previous section.
6913 The owning package should also provide a program
6914 that the other packages may use to modify the
6918 The related packages must use the provided program
6919 to make any desired modifications to the
6920 configuration file. They should either depend on
6921 the core package to guarantee that the configuration
6922 modifier program is available or accept gracefully
6923 that they cannot modify the configuration file if it
6924 is not. (This is in addition to the fact that the
6925 configuration file may not even be present in the
6932 Sometimes it's appropriate to create a new package which
6933 provides the basic infrastructure for the other packages
6934 and which manages the shared configuration files. (The
6935 <tt>sgml-base</tt> package is a good example.)
6940 <heading>User configuration files ("dotfiles")</heading>
6943 The files in <file>/etc/skel</file> will automatically be
6944 copied into new user accounts by <prgn>adduser</prgn>.
6945 No other program should reference the files in
6946 <file>/etc/skel</file>.
6950 Therefore, if a program needs a dotfile to exist in
6951 advance in <file>$HOME</file> to work sensibly, that dotfile
6952 should be installed in <file>/etc/skel</file> and treated as a
6957 However, programs that require dotfiles in order to
6958 operate sensibly are a bad thing, unless they do create
6959 the dotfiles themselves automatically.
6963 Furthermore, programs should be configured by the Debian
6964 default installation to behave as closely to the upstream
6965 default behaviour as possible.
6969 Therefore, if a program in a Debian package needs to be
6970 configured in some way in order to operate sensibly, that
6971 should be done using a site-wide configuration file placed
6972 in <file>/etc</file>. Only if the program doesn't support a
6973 site-wide default configuration and the package maintainer
6974 doesn't have time to add it may a default per-user file be
6975 placed in <file>/etc/skel</file>.
6979 <file>/etc/skel</file> should be as empty as we can make it.
6980 This is particularly true because there is no easy (or
6981 necessarily desirable) mechanism for ensuring that the
6982 appropriate dotfiles are copied into the accounts of
6983 existing users when a package is installed.
6989 <heading>Log files</heading>
6991 Log files should usually be named
6992 <file>/var/log/<var>package</var>.log</file>. If you have many
6993 log files, or need a separate directory for permission
6994 reasons (<file>/var/log</file> is writable only by
6995 <file>root</file>), you should usually create a directory named
6996 <file>/var/log/<var>package</var></file> and place your log
7001 Log files must be rotated occasionally so that they don't
7002 grow indefinitely; the best way to do this is to drop a log
7003 rotation configuration file into the directory
7004 <file>/etc/logrotate.d</file> and use the facilities provided by
7005 logrotate.<footnote>
7007 The traditional approach to log files has been to set up
7008 <em>ad hoc</em> log rotation schemes using simple shell
7009 scripts and cron. While this approach is highly
7010 customizable, it requires quite a lot of sysadmin work.
7011 Even though the original Debian system helped a little
7012 by automatically installing a system which can be used
7013 as a template, this was deemed not enough.
7017 The use of <prgn>logrotate</prgn>, a program developed
7018 by Red Hat, is better, as it centralizes log management.
7019 It has both a configuration file
7020 (<file>/etc/logrotate.conf</file>) and a directory where
7021 packages can drop their individual log rotation
7022 configurations (<file>/etc/logrotate.d</file>).
7025 Here is a good example for a logrotate config
7026 file (for more information see <manref name="logrotate"
7028 <example compact="compact">
7029 /var/log/foo/*.log {
7034 /etc/init.d/foo force-reload
7038 This rotates all files under <file>/var/log/foo</file>, saves 12
7039 compressed generations, and forces the daemon to reload its
7040 configuration information after the log rotation.
7044 Log files should be removed when the package is
7045 purged (but not when it is only removed). This should be
7046 done by the <prgn>postrm</prgn> script when it is called
7047 with the argument <tt>purge</tt> (see <ref
7048 id="removedetails">).
7053 <heading>Permissions and owners</heading>
7056 The rules in this section are guidelines for general use.
7057 If necessary you may deviate from the details below.
7058 However, if you do so you must make sure that what is done
7059 is secure and you should try to be as consistent as possible
7060 with the rest of the system. You should probably also
7061 discuss it on <prgn>debian-devel</prgn> first.
7065 Files should be owned by <tt>root.root</tt>, and made
7066 writable only by the owner and universally readable (and
7067 executable, if appropriate), that is mode 644 or 755.
7071 Directories should be mode 755 or (for group-writability)
7072 mode 2775. The ownership of the directory should be
7073 consistent with its mode: if a directory is mode 2775, it
7074 should be owned by the group that needs write access to
7079 Setuid and setgid executables should be mode 4755 or 2755
7080 respectively, and owned by the appropriate user or group.
7081 They should not be made unreadable (modes like 4711 or
7082 2711 or even 4111); doing so achieves no extra security,
7083 because anyone can find the binary in the freely available
7084 Debian package; it is merely inconvenient. For the same
7085 reason you should not restrict read or execute permissions
7086 on non-set-id executables.
7090 Some setuid programs need to be restricted to particular
7091 sets of users, using file permissions. In this case they
7092 should be owned by the uid to which they are set-id, and by
7093 the group which should be allowed to execute them. They
7094 should have mode 4754; again there is no point in making
7095 them unreadable to those users who must not be allowed to
7100 It is possible to arrange that the system administrator can
7101 reconfigure the package to correspond to their local
7102 security policy by changing the permissions on a binary:
7103 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7104 described below.<footnote>
7105 Ordinary files installed by <prgn>dpkg</prgn> (as
7106 opposed to <tt>conffile</tt>s and other similar objects)
7107 normally have their permissions reset to the distributed
7108 permissions when the package is reinstalled. However,
7109 the use of <prgn>dpkg-statoverride</prgn> overrides this
7110 default behaviour. If you use this method, you should
7111 remember to describe <prgn>dpkg-statoverride</prgn> in
7112 the package documentation; being a relatively new
7113 addition to Debian, it is probably not yet well-known.
7115 Another method you should consider is to create a group for
7116 people allowed to use the program(s) and make any setuid
7117 executables executable only by that group.
7121 If you need to create a new user or group for your package
7122 there are two possibilities. Firstly, you may need to
7123 make some files in the binary package be owned by this
7124 user or group, or you may need to compile the user or
7125 group id (rather than just the name) into the binary
7126 (though this latter should be avoided if possible, as in
7127 this case you need a statically allocated id).</p>
7130 If you need a statically allocated id, you must ask for a
7131 user or group id from the <tt>base-passwd</tt> maintainer,
7132 and must not release the package until you have been
7133 allocated one. Once you have been allocated one you must
7134 either make the package depend on a version of the
7135 <tt>base-passwd</tt> package with the id present in
7136 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7137 your package to create the user or group itself with the
7138 correct id (using <tt>adduser</tt>) in its
7139 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7140 the <prgn>postinst</prgn> is to be preferred if it is
7141 possible, otherwise a pre-dependency will be needed on the
7142 <tt>adduser</tt> package.)
7146 On the other hand, the program might be able to determine
7147 the uid or gid from the user or group name at runtime, so
7148 that a dynamically allocated id can be used. In this case
7149 you should choose an appropriate user or group name,
7150 discussing this on <prgn>debian-devel</prgn> and checking
7151 with the <package/base-passwd/ maintainer that it is unique and that
7152 they do not wish you to use a statically allocated id
7153 instead. When this has been checked you must arrange for
7154 your package to create the user or group if necessary using
7155 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7156 <prgn>postinst</prgn> script (again, the latter is to be
7157 preferred if it is possible).
7161 Note that changing the numeric value of an id associated
7162 with a name is very difficult, and involves searching the
7163 file system for all appropriate files. You need to think
7164 carefully whether a static or dynamic id is required, since
7165 changing your mind later will cause problems.
7168 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7170 This section is not intended as policy, but as a
7171 description of the use of <prgn>dpkg-statoverride</prgn>.
7175 <prgn>dpkg-statoverride</prgn> is a replacement for the
7176 deprecated <tt>suidmanager</tt> package. Packages which
7177 previously used <tt>suidmanager</tt> should have a
7178 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7179 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7180 and <tt>suidunregister</tt> should now be simply removed
7181 from the maintainer scripts.
7185 If a system administrator wishes to have a file (or
7186 directory or other such thing) installed with owner and
7187 permissions different from those in the distributed Debian
7188 package, he can use the <prgn>dpkg-statoverride</prgn>
7189 program to instruct <prgn>dpkg</prgn> to use the different
7190 settings every time the file is installed. Thus the
7191 package maintainer should distribute the files with their
7192 normal permissions, and leave it for the system
7193 administrator to make any desired changes. For example, a
7194 daemon which is normally required to be setuid root, but
7195 in certain situations could be used without being setuid,
7196 should be installed setuid in the <tt>.deb</tt>. Then the
7197 local system administrator can change this if they wish.
7198 If there are two standard ways of doing it, the package
7199 maintainer can use <tt>debconf</tt> to find out the
7200 preference, and call <prgn>dpkg-statoverride</prgn> in the
7201 maintainer script if necessary to accommodate the system
7202 administrator's choice.
7206 Given the above, <prgn>dpkg-statoverride</prgn> is
7207 essentially a tool for system administrators and would not
7208 normally be needed in the maintainer scripts. There is
7209 one type of situation, though, where calls to
7210 <prgn>dpkg-statoverride</prgn> would be needed in the
7211 maintainer scripts, and that involves packages which use
7212 dynamically allocated user or group ids. In such a
7213 situation, something like the following idiom can be very
7214 helpful in the package's <prgn>postinst</prgn>, where
7215 <tt>sysuser</tt> is a dynamically allocated id:
7217 for i in /usr/bin/foo /usr/sbin/bar
7219 if ! dpkg-statoverride --list $i >/dev/null
7221 dpkg-statoverride --update --add sysuser root 4755 $i
7225 The corresponding <tt>dpkg-statoverride --remove</tt>
7226 calls can then be made unconditionally when the package is
7234 <chapt id="customized-programs">
7235 <heading>Customized programs</heading>
7237 <sect id="arch-spec">
7238 <heading>Architecture specification strings</heading>
7241 If a program needs to specify an <em>architecture specification
7242 string</em> in some place, the following format should be
7243 used: <var>arch</var>-<var>os</var><footnote>
7244 The following architectures and operating systems are
7245 currently recognised by <prgn>dpkg-architecture</prgn>.
7246 The architecture, <tt><var>arch</var></tt>, is one of
7247 the following: <tt>alpha</tt>, <tt>arm</tt>,
7248 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7249 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7250 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7251 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7252 operating system, <tt><var>os</var></tt>, is one of:
7253 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7254 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7255 reserved for the GNU/Hurd operating system.
7260 Note that we don't want to use
7261 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7262 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7263 since this would make our programs incompatible with other
7264 Linux distributions. We also don't use something like
7265 <tt><var>arch</var>-unknown-linux</tt>, since the
7266 <tt>unknown</tt> does not look very good.
7271 <heading>Daemons</heading>
7274 The configuration files <file>/etc/services</file>,
7275 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7276 by the <prgn>netbase</prgn> package and must not be modified
7281 If a package requires a new entry in one of these files, the
7282 maintainer should get in contact with the
7283 <prgn>netbase</prgn> maintainer, who will add the entries
7284 and release a new version of the <prgn>netbase</prgn>
7289 The configuration file <file>/etc/inetd.conf</file> must not be
7290 modified by the package's scripts except via the
7291 <prgn>update-inetd</prgn> script or the
7292 <file>DebianNet.pm</file> Perl module. See their documentation
7293 for details on how to add entries.
7297 If a package wants to install an example entry into
7298 <file>/etc/inetd.conf</file>, the entry must be preceded with
7299 exactly one hash character (<tt>#</tt>). Such lines are
7300 treated as "commented out by user" by the
7301 <prgn>update-inetd</prgn> script and are not changed or
7302 activated during package updates.
7307 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7311 Some programs need to create pseudo-ttys. This should be done
7312 using Unix98 ptys if the C library supports it. The resulting
7313 program must not be installed setuid root, unless that
7314 is required for other functionality.
7318 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7319 <file>/var/log/lastlog</file> must be installed writeable by
7320 group <tt>utmp</tt>. Programs which need to modify those
7321 files must be installed setgid <tt>utmp</tt>.
7326 <heading>Editors and pagers</heading>
7329 Some programs have the ability to launch an editor or pager
7330 program to edit or display a text document. Since there are
7331 lots of different editors and pagers available in the Debian
7332 distribution, the system administrator and each user should
7333 have the possibility to choose his/her preferred editor and
7338 In addition, every program should choose a good default
7339 editor/pager if none is selected by the user or system
7344 Thus, every program that launches an editor or pager must
7345 use the EDITOR or PAGER environment variable to determine
7346 the editor or pager the user wishes to use. If these
7347 variables are not set, the programs <file>/usr/bin/editor</file>
7348 and <file>/usr/bin/pager</file> should be used, respectively.
7352 These two files are managed through the <prgn>dpkg</prgn>
7353 "alternatives" mechanism. Thus every package providing an
7354 editor or pager must call the
7355 <prgn>update-alternatives</prgn> script to register these
7360 If it is very hard to adapt a program to make use of the
7361 EDITOR or PAGER variables, that program may be configured to
7362 use <file>/usr/bin/sensible-editor</file> and
7363 <file>/usr/bin/sensible-pager</file> as the editor or pager
7364 program respectively. These are two scripts provided in the
7365 Debian base system that check the EDITOR and PAGER variables
7366 and launch the appropriate program, and fall back to
7367 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7368 variable is not set.
7372 A program may also use the VISUAL environment variable to
7373 determine the user's choice of editor. If it exists, it
7374 should take precedence over EDITOR. This is in fact what
7375 <file>/usr/bin/sensible-editor</file> does.
7379 It is not required for a package to depend on
7380 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7381 package to provide such virtual packages.<footnote>
7382 The Debian base system already provides an editor and a
7388 <sect id="web-appl">
7389 <heading>Web servers and applications</heading>
7392 This section describes the locations and URLs that should
7393 be used by all web servers and web applications in the
7400 Cgi-bin executable files are installed in the
7402 <example compact="compact">
7403 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7405 and should be referred to as
7406 <example compact="compact">
7407 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7412 <p>Access to HTML documents</p>
7415 HTML documents for a package are stored in
7416 <file>/usr/share/doc/<var>package</var></file>
7417 and can be referred to as
7418 <example compact="compact">
7419 http://localhost/doc/<var>package</var>/<var>filename</var>
7424 The web server should restrict access to the document
7425 tree so that only clients on the same host can read
7426 the documents. If the web server does not support such
7427 access controls, then it should not provide access at
7428 all, or ask about providing access during installation.
7433 <p>Web Document Root</p>
7436 Web Applications should try to avoid storing files in
7437 the Web Document Root. Instead they should use the
7438 /usr/share/doc/<var>package</var> directory for
7439 documents and register the Web Application via the
7440 menu package. If access to the web document root is
7441 unavoidable then use
7442 <example compact="compact">
7445 as the Document Root. This might be just a symbolic
7446 link to the location where the system administrator
7447 has put the real document root.
7455 <sect id="mail-transport-agents">
7456 <heading>Mail transport, delivery and user agents</heading>
7459 Debian packages which process electronic mail, whether mail
7460 user agents (MUAs) or mail transport agents (MTAs), must
7461 ensure that they are compatible with the configuration
7462 decisions below. Failure to do this may result in lost
7463 mail, broken <tt>From:</tt> lines, and other serious brain
7468 The mail spool is <file>/var/mail</file> and the interface to
7469 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7470 the FHS). On older systems, the mail spool may be
7471 physically located in <file>/var/spool/mail</file>, but all
7472 access to the mail spool should be via the
7473 <file>/var/mail</file> symlink. The mail spool is part of the
7474 base system and not part of the MTA package.
7478 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7479 programs (such as IMAP daemons) must lock the mailbox in an
7480 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7481 be combined with dot locking. To avoid deadlocks, a program
7482 should use <tt>fcntl()</tt> first and dot locking after
7483 this, or alternatively implement the two locking methods in
7484 a non blocking way<footnote>
7485 If it is not possible to establish both locks, the
7486 system shouldn't wait for the second lock to be
7487 established, but remove the first lock, wait a (random)
7488 time, and start over locking again.
7489 </footnote>. Using the functions <tt>maillock</tt> and
7490 <tt>mailunlock</tt> provided by the
7491 <tt>liblockfile*</tt><footnote>
7492 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7493 to use these functions.
7494 </footnote> packages is the recommended way to realize this.
7498 Mailboxes are generally mode 660
7499 <tt><var>user</var>.mail</tt> unless the system
7500 administrator has chosen otherwise. A MUA may remove a
7501 mailbox (unless it has nonstandard permissions) in which
7502 case the MTA or another MUA must recreate it if needed.
7503 Mailboxes must be writable by group mail.
7507 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7508 be setgid mail to do the locking mentioned above (and
7509 must obviously avoid accessing other users' mailboxes
7510 using this privilege).</p>
7513 <file>/etc/aliases</file> is the source file for the system mail
7514 aliases (e.g., postmaster, usenet, etc.), it is the one
7515 which the sysadmin and <prgn>postinst</prgn> scripts may
7516 edit. After <file>/etc/aliases</file> is edited the program or
7517 human editing it must call <prgn>newaliases</prgn>. All MTA
7518 packages must come with a <prgn>newaliases</prgn> program,
7519 even if it does nothing, but older MTA packages did not do
7520 this so programs should not fail if <prgn>newaliases</prgn>
7521 cannot be found. Note that because of this, all MTA
7522 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7523 <tt>Replaces: mail-transport-agent</tt> control file
7528 The convention of writing <tt>forward to
7529 <var>address</var></tt> in the mailbox itself is not
7530 supported. Use a <tt>.forward</tt> file instead.</p>
7533 The <prgn>rmail</prgn> program used by UUCP
7534 for incoming mail should be <file>/usr/sbin/rmail</file>.
7535 Likewise, <prgn>rsmtp</prgn>, for receiving
7536 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7540 If your package needs to know what hostname to use on (for
7541 example) outgoing news and mail messages which are generated
7542 locally, you should use the file <file>/etc/mailname</file>. It
7543 will contain the portion after the username and <tt>@</tt>
7544 (at) sign for email addresses of users on the machine
7545 (followed by a newline).
7549 Such package should check for the existence of this file
7550 when it is being configured. If it exists, it should be
7551 used without comment, although an MTA's configuration script
7552 may wish to prompt the user even if it finds that this file
7553 exists. If the file does not exist, the package should
7554 prompt the user for the value (preferably using
7555 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7556 as well as using it in the package's configuration. The
7557 prompt should make it clear that the name will not just be
7558 used by that package. For example, in this situation the
7559 <tt>inn</tt> package could say something like:
7560 <example compact="compact">
7561 Please enter the "mail name" of your system. This is the
7562 hostname portion of the address to be shown on outgoing
7563 news and mail messages. The default is
7564 <var>syshostname</var>, your system's host name. Mail
7565 name ["<var>syshostname</var>"]:
7567 where <var>syshostname</var> is the output of <tt>hostname
7573 <heading>News system configuration</heading>
7576 All the configuration files related to the NNTP (news)
7577 servers and clients should be located under
7578 <file>/etc/news</file>.</p>
7581 There are some configuration issues that apply to a number
7582 of news clients and server packages on the machine. These
7586 <tag><file>/etc/news/organization</file></tag>
7588 A string which should appear as the
7589 organization header for all messages posted
7590 by NNTP clients on the machine
7593 <tag><file>/etc/news/server</file></tag>
7595 Contains the FQDN of the upstream NNTP
7596 server, or localhost if the local machine is
7601 Other global files may be added as required for cross-package news
7608 <heading>Programs for the X Window System</heading>
7611 <heading>Providing X support and package priorities</heading>
7614 Programs that can be configured with support for the X
7615 Window System must be configured to do so and must declare
7616 any package dependencies necessary to satisfy their
7617 runtime requirements when using the X Window System. If
7618 such a package is of higher priority than the X packages
7619 on which it depends, it is required that either the
7620 X-specific components be split into a separate package, or
7621 that an alternative version of the package, which includes
7622 X support, be provided, or that the package's priority be
7628 <heading>Packages providing an X server</heading>
7631 Packages that provide an X server that, directly or
7632 indirectly, communicates with real input and display
7633 hardware should declare in their control data that they
7634 provide the virtual package <tt>xserver</tt>.<footnote>
7635 This implements current practice, and provides an
7636 actual policy for usage of the <tt>xserver</tt>
7637 virtual package which appears in the virtual packages
7638 list. In a nutshell, X servers that interface
7639 directly with the display and input hardware or via
7640 another subsystem (e.g., GGI) should provide
7641 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7642 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7648 <heading>Packages providing a terminal emulator</heading>
7651 Packages that provide a terminal emulator for the X Window
7652 System which meet the criteria listed below should declare
7653 in their control data that they provide the virtual
7654 package <tt>x-terminal-emulator</tt>. They should also
7655 register themselves as an alternative for
7656 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7661 To be an <tt>x-terminal-emulator</tt>, a program must:
7662 <list compact="compact">
7664 Be able to emulate a DEC VT100 terminal, or a
7665 compatible terminal.
7669 Support the command-line option <tt>-e
7670 <var>command</var></tt>, which creates a new
7671 terminal window<footnote>
7672 "New terminal window" does not necessarily mean
7673 a new top-level X window directly parented by
7674 the window manager; it could, if the terminal
7675 emulator application were so coded, be a new
7676 "view" in a multiple-document interface (MDI).
7678 and runs the specified <var>command</var>,
7679 interpreting the entirity of the rest of the command
7680 line as a command to pass straight to exec, in the
7681 manner that <tt>xterm</tt> does.
7685 Support the command-line option <tt>-T
7686 <var>title</var></tt>, which creates a new terminal
7687 window with the window title <var>title</var>.
7694 <heading>Packages providing a window manager</heading>
7697 Packages that provide a window manager should declare in
7698 their control data that they provide the virtual package
7699 <tt>x-window-manager</tt>. They should also register
7700 themselves as an alternative for
7701 <file>/usr/bin/x-window-manager</file>, with a priority
7702 calculated as follows:
7703 <list compact="compact">
7705 Start with a priority of 20.
7709 If the window manager supports the Debian menu
7710 system, add 20 points if this support is available
7711 in the package's default configuration (i.e., no
7712 configuration files belonging to the system or user
7713 have to be edited to activate the feature); if
7714 configuration files must be modified, add only 10
7720 If the window manager complies with <url
7721 id="http://www.freedesktop.org/standards/wm-spec.html"
7722 name="The Window Manager Specification Project">,
7723 written by the <url id="http://www.freedesktop.org/"
7724 name="Free Desktop Group">, add 40 points.
7728 If the window manager permits the X session to be
7729 restarted using a <em>different</em> window manager
7730 (without killing the X server) in its default
7731 configuration, add 10 points; otherwise add none.
7738 <heading>Packages providing fonts</heading>
7741 Packages that provide fonts for the X Window
7743 For the purposes of Debian Policy, a "font for the X
7744 Window System" is one which is accessed via X protocol
7745 requests. Fonts for the Linux console, for PostScript
7746 renderers, or any other purpose, do not fit this
7747 definition. Any tool which makes such fonts available
7748 to the X Window System, however, must abide by this
7751 must do a number of things to ensure that they are both
7752 available without modification of the X or font server
7753 configuration, and that they do not corrupt files used by
7754 other font packages to register information about
7758 Fonts of any type supported by the X Window System
7759 must be in a separate binary package from any
7760 executables, libraries, or documentation (except
7761 that specific to the fonts shipped, such as their
7762 license information). If one or more of the fonts
7763 so packaged are necessary for proper operation of
7764 the package with which they are associated the font
7765 package may be Recommended; if the fonts merely
7766 provide an enhancement, a Suggests relationship may
7767 be used. Packages must not Depend on font
7769 This is because the X server may retrieve fonts
7770 from the local filesystem or over the network
7771 from an X font server; the Debian package system
7772 is empowered to deal only with the local
7778 BDF fonts must be converted to PCF fonts with the
7779 <prgn>bdftopcf</prgn> utility (available in the
7780 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7781 placed in a directory that corresponds to their
7783 <list compact="compact">
7785 100 dpi fonts must be placed in
7786 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7790 75 dpi fonts must be placed in
7791 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7795 Character-cell fonts, cursor fonts, and other
7796 low-resolution fonts must be placed in
7797 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7803 Speedo fonts must be placed in
7804 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7808 Type 1 fonts must be placed in
7809 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7810 metric files are available, they must be placed here
7815 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7816 other than those listed above must be neither
7817 created nor used. (The <file>PEX</file>, <file>CID</file>,
7818 and <file>cyrillic</file> directories are excepted for
7819 historical reasons, but installation of files into
7820 these directories remains discouraged.)
7824 Font packages may, instead of placing files directly
7825 in the X font directories listed above, provide
7826 symbolic links in that font directory pointing to
7827 the files' actual location in the filesystem. Such
7828 a location must comply with the FHS.
7832 Font packages should not contain both 75dpi and
7833 100dpi versions of a font. If both are available,
7834 they should be provided in separate binary packages
7835 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7836 the names of the packages containing the
7837 corresponding fonts.
7841 Fonts destined for the <file>misc</file> subdirectory
7842 should not be included in the same package as 75dpi
7843 or 100dpi fonts; instead, they should be provided in
7844 a separate package with <tt>-misc</tt> appended to
7849 Font packages must not provide the files
7850 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7851 <file>fonts.scale</file> in a font directory:
7854 <file>fonts.dir</file> files must not be provided at all.
7858 <file>fonts.alias</file> and <file>fonts.scale</file>
7859 files, if needed, should be provided in the
7861 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7862 where <var>fontdir</var> is the name of the
7864 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7865 package's corresponding fonts are stored
7866 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7867 <var>package</var> is the name of the package
7868 that provides these fonts, and
7869 <var>extension</var> is either <tt>scale</tt>
7870 or <tt>alias</tt>, whichever corresponds to
7877 Font packages must declare a dependency on
7878 <tt>xutils (>> 4.0.3)</tt> in their control
7883 Font packages that provide one or more
7884 <file>fonts.scale</file> files as described above must
7885 invoke <prgn>update-fonts-scale</prgn> on each
7886 directory into which they installed fonts
7887 <em>before</em> invoking
7888 <prgn>update-fonts-dir</prgn> on that directory.
7889 This invocation must occur in both the
7890 <prgn>postinst</prgn> (for all arguments) and
7891 <prgn>postrm</prgn> (for all arguments except
7892 <tt>upgrade</tt>) scripts.
7896 Font packages that provide one or more
7897 <file>fonts.alias</file> files as described above must
7898 invoke <prgn>update-fonts-alias</prgn> on each
7899 directory into which they installed fonts. This
7900 invocation must occur in both the
7901 <prgn>postinst</prgn> (for all arguments) and
7902 <prgn>postrm</prgn> (for all arguments except
7903 <tt>upgrade</tt>) scripts.
7907 Font packages must invoke
7908 <prgn>update-fonts-dir</prgn> on each directory into
7909 which they installed fonts. This invocation must
7910 occur in both the <prgn>postinst</prgn> (for all
7911 arguments) and <prgn>postrm</prgn> (for all
7912 arguments except <tt>upgrade</tt>) scripts.
7916 Font packages must not provide alias names for the
7917 fonts they include which collide with alias names
7918 already in use by fonts already packaged.
7922 Font packages must not provide fonts with the same
7923 XLFD registry name as another font already packaged.
7930 <heading>Application defaults files</heading>
7933 Application defaults files must be installed in the
7934 directory <file>/etc/X11/app-defaults/</file> (use of a
7935 localized subdirectory of <file>/etc/X11/</file> as described
7936 in the <em>X Toolkit Intrinsics - C Language
7937 Interface</em> manual is also permitted). They must be
7938 registered as <tt>conffile</tt>s or handled as
7939 configuration files. Packages must not provide the
7940 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7944 Customization of programs' X resources may also be
7945 supported with the provision of a file with the same name
7946 as that of the package placed in the
7947 <file>/etc/X11/Xresources/</file> directory, which must
7948 registered as a <tt>conffile</tt> or handled as a
7949 configuration file.<footnote>
7950 Note that this mechanism is not the same as using
7951 app-defaults; app-defaults are tied to the client
7952 binary on the local filesystem, whereas X resources
7953 are stored in the X server and affect all connecting
7956 <em>Important:</em> packages that install files into the
7957 <file>/etc/X11/Xresources/</file> directory must conflict with
7958 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7959 it is possible for the installing package to destroy a
7960 previously-existing <file>/etc/X11/Xresources</file> file
7961 which had been customized by the system administrator.
7966 <heading>Installation directory issues</heading>
7969 Packages using the X Window System should not be
7970 configured to install files under the <file>/usr/X11R6/</file>
7971 directory unless they use <prgn>imake</prgn>. The
7972 <file>/usr/X11R6/</file> directory hierarchy should be
7973 regarded as deprecated for all packages except the X
7974 Window System itself, and those which use the
7975 <prgn>imake</prgn> program it provides, in which case the
7976 packages may transition out of the <file>/usr/X11R6/</file>
7977 directory at the maintainer's discretion.<footnote>
7978 <prgn>Imake</prgn>-using programs are exempt because,
7979 as long as they are written correctly, the pathnames
7980 they use to locate resources and install themselves
7981 are derived wholly from the X Window System
7982 configuration. Thus, in the event that the X Window
7983 System moves to <file>/usr/X11R7/</file>,
7984 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7985 that is required for these programs is a recompile
7986 against the corresponding X Window System library
7987 development packages.
7992 Programs that use GNU <prgn>autoconf</prgn> and
7993 <prgn>automake</prgn> are usually easily configured at
7994 compile time to use <file>/usr/</file> instead of
7995 <file>/usr/X11R6/</file>, and this should be done whenever
7996 possible. Configuration files for window managers and
7997 display managers should be placed in a subdirectory of
7998 <file>/etc/X11/</file> corresponding to the package name due
7999 to these programs' tight integration with the mechanisms
8000 of the X Window System. Application-level programs should
8001 use the <file>/etc/</file> directory unless otherwise mandated
8006 The installation of files into subdirectories
8007 of <file>/usr/X11R6/include/X11/</file> and
8008 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8009 package maintainers should determine if subdirectories of
8010 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8011 instead. (The use of symbolic links from the
8012 <file>X11R6</file> directories to other FHS-compliant
8013 locations is encouraged if the program is not easily
8014 configured to look elsewhere for its files.)
8018 Packages must not provide or install files into the directories
8019 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8020 <file>/usr/lib/X11/</file>. Files within a package should,
8021 however, make reference to these directories, rather than
8022 their <tt>X11R6</tt>-named counterparts
8023 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8024 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8025 referred to have not been moved to other FHS-compliant
8031 <heading>The OSF/Motif and OpenMotif libraries</heading>
8034 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8035 OpenMotif libraries</em><footnote>
8036 OSF/Motif and OpenMotif are collectively referred to as
8037 "Motif" in this policy document.
8039 should be compiled against and tested with LessTif (a free
8040 re-implementation of Motif) instead. If the maintainer
8041 judges that the program or programs do not work
8042 sufficiently well with LessTif to be distributed and
8043 supported, but do so when compiled against Motif, then two
8044 versions of the package should be created; one linked
8045 statically against Motif and with <tt>-smotif</tt>
8046 appended to the package name, and one linked dynamically
8047 against Motif and with <tt>-dmotif</tt> appended to the
8052 Both Motif-linked versions are dependent
8053 upon non-DFSG-compliant software and thus cannot be
8054 uploaded to the <em>main</em> distribution; if the
8055 software is itself DFSG-compliant it may be uploaded to
8056 the <em>contrib</em> distribution. While known existing
8057 versions of Motif permit unlimited redistribution of
8058 binaries linked against the library (whether statically or
8059 dynamically), it is the package maintainer's
8060 responsibility to determine whether this is permitted by
8061 the license of the copy of Motif in his or her possession.
8067 <heading>Perl programs and modules</heading>
8070 Perl programs and modules should follow the current Perl policy.
8074 The Perl policy can be found in the <tt>perl-policy</tt>
8075 files in the <tt>debian-policy</tt> package.
8076 It is also available from the Debian web mirrors at
8077 <tt><url name="/doc/packaging-manuals/perl-policy/"
8078 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
8079 and from the Debian archive mirrors at
8080 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
8081 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
8086 <heading>Emacs lisp programs</heading>
8089 Please refer to the "Debian Emacs Policy" for details of how to
8090 package emacs lisp programs.
8094 The Emacs policy is available in
8095 <file>debian-emacs-policy.gz</file> of the
8096 <package>emacsen-common</package> package.
8097 It is also available from the Debian web mirrors at
8098 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8099 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8104 <heading>Games</heading>
8107 The permissions on <file>/var/games</file> are mode 755, owner
8108 <tt>root</tt> and group <tt>root</tt>.
8112 Each game decides on its own security policy.</p>
8115 Games which require protected, privileged access to
8116 high-score files, savegames, etc., may be made
8117 set-<em>group</em>-id (mode 2755) and owned by
8118 <tt>root.games</tt>, and use files and directories with
8119 appropriate permissions (770 <tt>root.games</tt>, for
8120 example). They must not be made
8121 set-<em>user</em>-id, as this causes security problems. (If
8122 an attacker can subvert any set-user-id game they can
8123 overwrite the executable of any other, causing other players
8124 of these games to run a Trojan horse program. With a
8125 set-group-id game the attacker only gets access to less
8126 important game data, and if they can get at the other
8127 players' accounts at all it will take considerably more
8131 Some packages, for example some fortune cookie programs, are
8132 configured by the upstream authors to install with their
8133 data files or other static information made unreadable so
8134 that they can only be accessed through set-id programs
8135 provided. You should not do this in a Debian package: anyone can
8136 download the <file>.deb</file> file and read the data from it,
8137 so there is no point making the files unreadable. Not
8138 making the files unreadable also means that you don't have
8139 to make so many programs set-id, which reduces the risk of a
8143 As described in the FHS, binaries of games should be
8144 installed in the directory <file>/usr/games</file>. This also
8145 applies to games that use the X Window System. Manual pages
8146 for games (X and non-X games) should be installed in
8147 <file>/usr/share/man/man6</file>.</p>
8153 <heading>Documentation</heading>
8156 <heading>Manual pages</heading>
8159 You should install manual pages in <prgn>nroff</prgn> source
8160 form, in appropriate places under <file>/usr/share/man</file>.
8161 You should only use sections 1 to 9 (see the FHS for more
8162 details). You must not install a preformatted "cat page".
8166 Each program, utility, and function should have an
8167 associated manual page included in the same package. It is
8168 suggested that all configuration files also have a manual
8169 page included as well. Manual pages for protocols and other
8170 auxiliary things are optional.
8174 If no manual page is available, this is considered as a bug
8175 and should be reported to the Debian Bug Tracking System (the
8176 maintainer of the package is allowed to write this bug report
8177 themselves, if they so desire). Do not close the bug report
8178 until a proper manpage is available.<footnote>
8179 It is not very hard to write a man page. See the
8180 <url id="http://www.schweikhardt.net/man_page_howto.html"
8181 name="Man-Page-HOWTO">,
8182 <manref name="man" section="7">, the examples
8183 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8184 the helper programs <prgn>help2man</prgn>, or the
8185 directory <file>/usr/share/doc/man-db/examples</file>.
8190 You may forward a complaint about a missing manpage to the
8191 upstream authors, and mark the bug as forwarded in the
8192 Debian bug tracking system. Even though the GNU Project do
8193 not in general consider the lack of a manpage to be a bug,
8194 we do; if they tell you that they don't consider it a bug
8195 you should leave the bug in our bug tracking system open
8200 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8204 If one manpage needs to be accessible via several names it
8205 is better to use a symbolic link than the <file>.so</file>
8206 feature, but there is no need to fiddle with the relevant
8207 parts of the upstream source to change from <file>.so</file> to
8208 symlinks: don't do it unless it's easy. You should not
8209 create hard links in the manual page directories, nor put
8210 absolute filenames in <file>.so</file> directives. The filename
8211 in a <file>.so</file> in a manpage should be relative to the
8212 base of the manpage tree (usually
8213 <file>/usr/share/man</file>). If you do not create any links
8214 (whether symlinks, hard links, or <tt>.so</tt> directives)
8215 in the filesystem to the alternate names of the manpage,
8216 then you should not rely on <prgn>man</prgn> finding your
8217 manpage under those names based solely on the information in
8218 the manpage's header.<footnote>
8219 Supporting this in <prgn>man</prgn> often requires
8220 unreasonable processing time to find a manual page or to
8221 report that none exists, and moves knowledge into man's
8222 database that would be better left in the filesystem.
8223 This support is therefore deprecated and will cease to
8224 be present in the future.
8230 <heading>Info documents</heading>
8233 Info documents should be installed in <file>/usr/share/info</file>.
8234 They should be compressed with <tt>gzip -9</tt>.
8238 Your package should call <prgn>install-info</prgn> to update
8239 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8240 script when called with a <tt>configure</tt> argument, for
8242 <example compact="compact">
8243 install-info --quiet --section Development Development \
8244 /usr/share/info/foobar.info
8248 It is a good idea to specify a section for the location of
8249 your program; this is done with the <tt>--section</tt>
8250 switch. To determine which section to use, you should look
8251 at <file>/usr/share/info/dir</file> on your system and choose the most
8252 relevant (or create a new section if none of the current
8253 sections are relevant). Note that the <tt>--section</tt>
8254 flag takes two arguments; the first is a regular expression
8255 to match (case-insensitively) against an existing section,
8256 the second is used when creating a new one.</p>
8259 You should remove the entries in the <prgn>prerm</prgn>
8260 script when called with a <tt>remove</tt> argument:
8261 <example compact="compact">
8262 install-info --quiet --remove /usr/share/info/foobar.info
8266 If <prgn>install-info</prgn> cannot find a description entry
8267 in the Info file you must supply one. See <manref
8268 name="install-info" section="8"> for details.</p>
8272 <heading>Additional documentation</heading>
8275 Any additional documentation that comes with the package may
8276 be installed at the discretion of the package maintainer.
8277 Text documentation should be installed in the directory
8278 <file>/usr/share/doc/<var>package</var></file>, where
8279 <var>package</var> is the name of the package, and
8280 compressed with <tt>gzip -9</tt> unless it is small.
8284 If a package comes with large amounts of documentation which
8285 many users of the package will not require you should create
8286 a separate binary package to contain it, so that it does not
8287 take up disk space on the machines of users who do not need
8288 or want it installed.</p>
8291 It is often a good idea to put text information files
8292 (<file>README</file>s, changelogs, and so forth) that come with
8293 the source package in <file>/usr/share/doc/<var>package</var></file>
8294 in the binary package. However, you don't need to install
8295 the instructions for building and installing the package, of
8299 Packages must not require the existence of any files in
8300 <file>/usr/share/doc/</file> in order to function
8302 The system administrator should be able to
8303 delete files in <file>/usr/share/doc/</file> without causing
8304 any programs to break.
8306 Any files that are referenced by programs but are also
8307 useful as standalone documentation should be installed under
8308 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8309 <file>/usr/share/doc/<var>package</var></file>.
8313 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8314 link to another directory in <file>/usr/share/doc</file> only if
8315 the two packages both come from the same source and the
8316 first package Depends on the second.
8320 Former Debian releases placed all additional documentation
8321 in <file>/usr/doc/<var>package</var></file>. This has been
8322 changed to <file>/usr/share/doc/<var>package</var></file>,
8323 and packages must not put documentation in the directory
8324 <file>/usr/doc/<var>package</var></file>. <footnote>
8325 At this phase of the transition, we no longer require a
8326 symbolic link in <file>/usr/doc/</file>. At a later point,
8327 policy shall change to make the symbolic links a bug.
8333 <heading>Preferred documentation formats</heading>
8336 The unification of Debian documentation is being carried out
8340 If your package comes with extensive documentation in a
8341 markup format that can be converted to various other formats
8342 you should if possible ship HTML versions in a binary
8343 package, in the directory
8344 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8345 its subdirectories.<footnote>
8346 The rationale: The important thing here is that HTML
8347 docs should be available in <em>some</em> package, not
8348 necessarily in the main binary package.
8353 Other formats such as PostScript may be provided at the
8354 package maintainer's discretion.
8358 <sect id="copyrightfile">
8359 <heading>Copyright information</heading>
8362 Every package must be accompanied by a verbatim copy of its
8363 copyright and distribution license in the file
8364 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8365 file must neither be compressed nor be a symbolic link.
8369 In addition, the copyright file must say where the upstream
8370 sources (if any) were obtained. It should name the original
8371 authors of the package and the Debian maintainer(s) who were
8372 involved with its creation.</p>
8375 A copy of the file which will be installed in
8376 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8377 be in <file>debian/copyright</file> in the source package.
8381 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8382 link to another directory in <file>/usr/share/doc</file> only if
8383 the two packages both come from the same source and the
8384 first package Depends on the second. These rules are
8385 important because copyrights must be extractable by
8390 Packages distributed under the UCB BSD license, the Artistic
8391 license, the GNU GPL, and the GNU LGPL should refer to the
8392 files <file>/usr/share/common-licenses/BSD</file>,
8393 <file>/usr/share/common-licenses/Artistic</file>,
8394 <file>/usr/share/common-licenses/GPL</file>, and
8395 <file>/usr/share/common-licenses/LGPL</file> respectively,
8396 rather than quoting them in the copyright file.
8400 You should not use the copyright file as a general <file>README</file>
8401 file. If your package has such a file it should be
8402 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8403 <file>README.Debian</file> or some other appropriate place.</p>
8407 <heading>Examples</heading>
8410 Any examples (configurations, source files, whatever),
8411 should be installed in a directory
8412 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8413 files should not be referenced by any program: they're there
8414 for the benefit of the system administrator and users as
8415 documentation only. Architecture-specific example files
8416 should be installed in a directory
8417 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8419 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8420 latter directory itself may be a symbolic link to the
8425 If the purpose of a package is to provide examples, then the
8426 example files may be installed into
8427 <file>/usr/share/doc/<var>package</var></file>.
8431 <sect id="changelogs">
8432 <heading>Changelog files</heading>
8435 Packages that are not Debian-native must contain a
8436 compressed copy of the <file>debian/changelog</file> file from
8437 the Debian source tree in
8438 <file>/usr/share/doc/<var>package</var></file> with the name
8439 <file>changelog.Debian.gz</file>.
8443 If an upstream changelog is available, it should be accessible as
8444 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8445 plain text. If the upstream changelog is distributed in
8446 HTML, it should be made available in that form as
8447 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8448 and a plain text <file>changelog.gz</file> should be generated
8449 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8450 the upstream changelog files do not already conform to this
8451 naming convention, then this may be achieved either by
8452 renaming the files, or by adding a symbolic link, at the
8453 maintainer's discretion.<footnote>
8454 Rationale: People should not have to look in places for
8455 upstream changelogs merely because they are given
8456 different names or are distributed in HTML format.
8461 All of these files should be installed compressed using
8462 <tt>gzip -9</tt>, as they will become large with time even
8463 if they start out small.
8467 If the package has only one changelog which is used both as
8468 the Debian changelog and the upstream one because there is
8469 no separate upstream maintainer then that changelog should
8470 usually be installed as
8471 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8472 there is a separate upstream maintainer, but no upstream
8473 changelog, then the Debian changelog should still be called
8474 <file>changelog.Debian.gz</file>.
8478 For details about the format and contents of the Debian
8479 changelog file, please see <ref id="dpkgchangelog">.
8484 <appendix id="pkg-scope">
8485 <heading>Introduction and scope of these appendices</heading>
8488 These appendices are taken essentially verbatim from the
8489 now-deprecated Packaging Manual, version 3.2.1.0. They are
8490 the chapters which are likely to be of use to package
8491 maintainers and which have not already been included in the
8492 policy document itself. Most of these sections are very likely
8493 not relevant to policy; they should be treated as
8494 documentation for the packaging system. Please note that these
8495 appendices are included for convenience, and for historical
8496 reasons: they used to be part of policy package, and they have
8497 not yet been incorporated into dpkg documentation. However,
8498 they still have value, and hence they are presented here.
8502 They have not yet been checked to ensure that they are
8503 compatible with the contents of policy, and if there are any
8504 contradictions, the version in the main policy document takes
8505 precedence. The remaining chapters of the old Packaging
8506 Manual have also not been read in detail to ensure that there
8507 are not parts which have been left out. Both of these will be
8512 Certain parts of the Packaging manual were integrated into the
8513 Policy Manual proper, and removed from the appendices. Links
8514 have been placed from the old locations to the new ones.
8518 <prgn>dpkg</prgn> is a suite of programs for creating binary
8519 package files and installing and removing them on Unix
8521 <prgn>dpkg</prgn> is targetted primarily at Debian
8522 GNU/Linux, but may work on or be ported to other
8528 The binary packages are designed for the management of
8529 installed executable programs (usually compiled binaries) and
8530 their associated data, though source code examples and
8531 documentation are provided as part of some packages.</p>
8534 This manual describes the technical aspects of creating Debian
8535 binary packages (<file>.deb</file> files). It documents the
8536 behaviour of the package management programs
8537 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8538 they interact with packages.</p>
8541 It also documents the interaction between
8542 <prgn>dselect</prgn>'s core and the access method scripts it
8543 uses to actually install the selected packages, and describes
8544 how to create a new access method.</p>
8547 This manual does not go into detail about the options and
8548 usage of the package building and installation tools. It
8549 should therefore be read in conjuction with those programs'
8554 The utility programs which are provided with <prgn>dpkg</prgn>
8555 for managing various system configuration and similar issues,
8556 such as <prgn>update-rc.d</prgn> and
8557 <prgn>install-info</prgn>, are not described in detail here -
8558 please see their manpages.
8562 It is assumed that the reader is reasonably familiar with the
8563 <prgn>dpkg</prgn> System Administrators' manual.
8564 Unfortunately this manual does not yet exist.
8568 The Debian version of the FSF's GNU hello program is provided
8569 as an example for people wishing to create Debian
8570 packages. The Debian <prgn>debmake</prgn> package is
8571 recommended as a very helpful tool in creating and maintaining
8572 Debian packages. However, while the tools and examples are
8573 helpful, they do not replace the need to read and follow the
8574 Policy and Programmer's Manual.</p>
8577 <appendix id="pkg-binarypkg">
8578 <heading>Binary packages (from old Packaging Manual)</heading>
8581 The binary package has two main sections. The first part
8582 consists of various control information files and scripts used
8583 by <prgn>dpkg</prgn> when installing and removing. See <ref
8584 id="pkg-controlarea">.
8588 The second part is an archive containing the files and
8589 directories to be installed.
8593 In the future binary packages may also contain other
8594 components, such as checksums and digital signatures. The
8595 format for the archive is described in full in the
8596 <file>deb(5)</file> manpage.
8600 <sect id="pkg-bincreating"><heading>Creating package files -
8601 <prgn>dpkg-deb</prgn>
8605 All manipulation of binary package files is done by
8606 <prgn>dpkg-deb</prgn>; it's the only program that has
8607 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8608 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8609 will spot that the options requested are appropriate to
8610 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8615 In order to create a binary package you must make a
8616 directory tree which contains all the files and directories
8617 you want to have in the filesystem data part of the package.
8618 In Debian-format source packages this directory is usually
8619 <file>debian/tmp</file>, relative to the top of the package's
8624 They should have the locations (relative to the root of the
8625 directory tree you're constructing) ownerships and
8626 permissions which you want them to have on the system when
8631 With current versions of <prgn>dpkg</prgn> the uid/username
8632 and gid/groupname mappings for the users and groups being
8633 used should be the same on the system where the package is
8634 built and the one where it is installed.
8638 You need to add one special directory to the root of the
8639 miniature filesystem tree you're creating:
8640 <prgn>DEBIAN</prgn>. It should contain the control
8641 information files, notably the binary package control file
8642 (see <ref id="pkg-controlfile">).
8646 The <prgn>DEBIAN</prgn> directory will not appear in the
8647 filesystem archive of the package, and so won't be installed
8648 by <prgn>dpkg</prgn> when the package is installed.
8652 When you've prepared the package, you should invoke:
8654 dpkg --build <var>directory</var>
8659 This will build the package in
8660 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8661 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8662 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8667 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8668 to examine the contents of this newly-created file. You may find the
8669 output of following commands enlightening:
8671 dpkg-deb --info <var>filename</var>.deb
8672 dpkg-deb --contents <var>filename</var>.deb
8673 dpkg --contents <var>filename</var>.deb
8675 To view the copyright file for a package you could use this command:
8677 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8682 <sect id="pkg-controlarea">
8683 <heading>Package control information files</heading>
8686 The control information portion of a binary package is a
8687 collection of files with names known to <prgn>dpkg</prgn>.
8688 It will treat the contents of these files specially - some
8689 of them contain information used by <prgn>dpkg</prgn> when
8690 installing or removing the package; others are scripts which
8691 the package maintainer wants <prgn>dpkg</prgn> to run.
8695 It is possible to put other files in the package control
8696 area, but this is not generally a good idea (though they
8697 will largely be ignored).
8701 Here is a brief list of the control info files supported by
8702 <prgn>dpkg</prgn> and a summary of what they're used for.
8707 <tag><tt>control</tt>
8710 This is the key description file used by
8711 <prgn>dpkg</prgn>. It specifies the package's name
8712 and version, gives its description for the user,
8713 states its relationships with other packages, and so
8714 forth. See <ref id="sourcecontrolfiles"> and
8715 <ref id="binarycontrolfiles">.
8719 It is usually generated automatically from information
8720 in the source package by the
8721 <prgn>dpkg-gencontrol</prgn> program, and with
8722 assistance from <prgn>dpkg-shlibdeps</prgn>.
8723 See <ref id="pkg-sourcetools">.
8727 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8732 These are exectuable files (usually scripts) which
8733 <prgn>dpkg</prgn> runs during installation, upgrade
8734 and removal of packages. They allow the package to
8735 deal with matters which are particular to that package
8736 or require more complicated processing than that
8737 provided by <prgn>dpkg</prgn>. Details of when and
8738 how they are called are in <ref id="maintainerscripts">.
8742 It is very important to make these scripts idempotent.
8743 See <ref id="idempotency">.
8747 The maintainer scripts are guaranteed to run with a
8748 controlling terminal and can interact with the user.
8749 See <ref id="controllingterminal">.
8753 <tag><tt>conffiles</tt>
8756 This file contains a list of configuration files which
8757 are to be handled automatically by <prgn>dpkg</prgn>
8758 (see <ref id="pkg-conffiles">). Note that not necessarily
8759 every configuration file should be listed here.
8762 <tag><tt>shlibs</tt>
8765 This file contains a list of the shared libraries
8766 supplied by the package, with dependency details for
8767 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8768 when it determines what dependencies are required in a
8769 package control file. The <tt>shlibs</tt> file format
8770 is described on <ref id="shlibs">.
8775 <sect id="pkg-controlfile">
8776 <heading>The main control information file: <tt>control</tt></heading>
8779 The most important control information file used by
8780 <prgn>dpkg</prgn> when it installs a package is
8781 <tt>control</tt>. It contains all the package's "vital
8786 The binary package control files of packages built from
8787 Debian sources are made by a special tool,
8788 <prgn>dpkg-gencontrol</prgn>, which reads
8789 <file>debian/control</file> and <file>debian/changelog</file> to
8790 find the information it needs. See <ref id="pkg-sourcepkg"> for
8795 The fields in binary package control files are listed in
8796 <ref id="binarycontrolfiles">.
8800 A description of the syntax of control files and the purpose
8801 of the fields is available in <ref id="controlfields">.
8806 <heading>Time Stamps</heading>
8809 See <ref id="timestamps">.
8814 <appendix id="pkg-sourcepkg">
8815 <heading>Source packages (from old Packaging Manual) </heading>
8818 The Debian binary packages in the distribution are generated
8819 from Debian sources, which are in a special format to assist
8820 the easy and automatic building of binaries.
8823 <sect id="pkg-sourcetools">
8824 <heading>Tools for processing source packages</heading>
8827 Various tools are provided for manipulating source packages;
8828 they pack and unpack sources and help build of binary
8829 packages and help manage the distribution of new versions.
8833 They are introduced and typical uses described here; see
8834 <manref name="dpkg-source" section="1"> for full
8835 documentation about their arguments and operation.
8839 For examples of how to construct a Debian source package,
8840 and how to use those utilities that are used by Debian
8841 source packages, please see the <prgn>hello</prgn> example
8845 <sect1 id="pkg-dpkg-source">
8847 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8852 This program is frequently used by hand, and is also
8853 called from package-independent automated building scripts
8854 such as <prgn>dpkg-buildpackage</prgn>.
8858 To unpack a package it is typically invoked with
8860 dpkg-source -x <var>.../path/to/filename</var>.dsc
8865 with the <file><var>filename</var>.tar.gz</file> and
8866 <file><var>filename</var>.diff.gz</file> (if applicable) in
8867 the same directory. It unpacks into
8868 <file><var>package</var>-<var>version</var></file>, and if
8870 <file><var>package</var>-<var>version</var>.orig</file>, in
8871 the current directory.
8875 To create a packed source archive it is typically invoked:
8877 dpkg-source -b <var>package</var>-<var>version</var>
8882 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8883 <file>.diff.gz</file> (if appropriate) in the current
8884 directory. <prgn>dpkg-source</prgn> does not clean the
8885 source tree first - this must be done separately if it is
8890 See also <ref id="pkg-sourcearchives">.</p>
8894 <sect1 id="pkg-dpkg-buildpackage">
8896 <prgn>dpkg-buildpackage</prgn> - overall package-building
8901 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8902 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8903 targets <tt>clean</tt>, <tt>build</tt> and
8904 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8905 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8906 source and binary package upload.
8910 It is usually invoked by hand from the top level of the
8911 built or unbuilt source directory. It may be invoked with
8912 no arguments; useful arguments include:
8913 <taglist compact="compact">
8914 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8917 Do not sign the <tt>.changes</tt> file or the
8918 source package <tt>.dsc</tt> file, respectively.</p>
8920 <tag><tt>-p<var>sign-command</var></tt></tag>
8923 Invoke <var>sign-command</var> instead of finding
8924 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8925 <var>sign-command</var> must behave just like
8926 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
8928 <tag><tt>-r<var>root-command</var></tt></tag>
8931 When root privilege is required, invoke the command
8932 <var>root-command</var>. <var>root-command</var>
8933 should invoke its first argument as a command, from
8934 the <prgn>PATH</prgn> if necessary, and pass its
8935 second and subsequent arguments to the command it
8936 calls. If no <var>root-command</var> is supplied
8937 then <var>dpkg-buildpackage</var> will take no
8938 special action to gain root privilege, so that for
8939 most packages it will have to be invoked as root to
8942 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8945 Two types of binary-only build and upload - see
8946 <manref name="dpkg-source" section="1">.
8953 <sect1 id="pkg-dpkg-gencontrol">
8955 <prgn>dpkg-gencontrol</prgn> - generates binary package
8960 This program is usually called from <file>debian/rules</file>
8961 (see <ref id="pkg-sourcetree">) in the top level of the source
8966 This is usually done just before the files and directories in the
8967 temporary directory tree where the package is being built have their
8968 permissions and ownerships set and the package is constructed using
8969 <prgn>dpkg-deb/</prgn>
8971 This is so that the control file which is produced has
8972 the right permissions
8977 <prgn>dpkg-gencontrol</prgn> must be called after all the
8978 files which are to go into the package have been placed in
8979 the temporary build directory, so that its calculation of
8980 the installed size of a package is correct.
8984 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8985 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8986 variable substitutions created by
8987 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8992 For a package which generates only one binary package, and
8993 which builds it in <file>debian/tmp</file> relative to the top
8994 of the source package, it is usually sufficient to call
8995 <prgn>dpkg-gencontrol</prgn>.
8999 Sources which build several binaries will typically need
9002 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9003 </example> The <tt>-P</tt> tells
9004 <prgn>dpkg-gencontrol</prgn> that the package is being
9005 built in a non-default directory, and the <tt>-p</tt>
9006 tells it which package's control file should be generated.
9010 <prgn>dpkg-gencontrol</prgn> also adds information to the
9011 list of files in <file>debian/files</file>, for the benefit of
9012 (for example) a future invocation of
9013 <prgn>dpkg-genchanges</prgn>.</p>
9016 <sect1 id="pkg-dpkg-shlibdeps">
9018 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9023 This program is usually called from <file>debian/rules</file>
9024 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9025 id="pkg-sourcetree">), in the top level of the source tree.
9029 Its arguments are executables.
9032 In a forthcoming dpkg version,
9033 <prgn>dpkg-shlibdeps</prgn> would be required to be
9034 called on shared libraries as well.
9037 They may be specified either in the locations in the
9038 source tree where they are created or in the locations
9039 in the temporary build tree where they are installed
9040 prior to binary package creation.
9042 </footnote> for which shared library dependencies should
9043 be included in the binary package's control file.
9047 If some of the found shared libraries should only
9048 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9049 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9050 by using the <tt>-d<var>dependency-field</var></tt> option
9051 before those executable(s). (Each <tt>-d</tt> option
9052 takes effect until the next <tt>-d</tt>.)
9056 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9057 output control file to be modified. Instead by default it
9058 adds to the <file>debian/substvars</file> file variable
9059 settings like <tt>shlibs:Depends</tt>. These variable
9060 settings must be referenced in dependency fields in the
9061 appropriate per-binary-package sections of the source
9066 For example, a package that generates an essential part
9067 which requires dependencies, and optional parts that
9068 which only require a recommendation, would separate those
9069 two sets of dependencies into two different fields.<footnote>
9070 At the time of writing, an example for this was the
9071 <package/xmms/ package, with Depends used for the xmms
9072 executable, Recommends for the plug-ins and Suggests for
9073 even more optional features provided by unzip.
9075 It can say in its <file>debian/rules</file>:
9077 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9078 -dRecommends <var>optionalpart anotheroptionalpart</var>
9080 and then in its main control file <file>debian/control</file>:
9083 Depends: ${shlibs:Pre-Depends}
9084 Recommends: ${shlibs:Recommends}
9090 Sources which produce several binary packages with
9091 different shared library dependency requirements can use
9092 the <tt>-p<var>varnameprefix</var></tt> option to override
9093 the default <tt>shlibs:</tt> prefix (one invocation of
9094 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9095 They can thus produce several sets of dependency
9096 variables, each of the form
9097 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9098 which can be referred to in the appropriate parts of the
9099 binary package control files.
9104 <sect1 id="pkg-dpkg-distaddfile">
9106 <prgn>dpkg-distaddfile</prgn> - adds a file to
9107 <file>debian/files</file>
9111 Some packages' uploads need to include files other than
9112 the source and binary package files.
9116 <prgn>dpkg-distaddfile</prgn> adds a file to the
9117 <file>debian/files</file> file so that it will be included in
9118 the <file>.changes</file> file when
9119 <prgn>dpkg-genchanges</prgn> is run.
9123 It is usually invoked from the <tt>binary</tt> target of
9124 <file>debian/rules</file>:
9126 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9128 The <var>filename</var> is relative to the directory where
9129 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9130 is usually the directory above the top level of the source
9131 tree. The <file>debian/rules</file> target should put the
9132 file there just before or just after calling
9133 <prgn>dpkg-distaddfile</prgn>.
9137 The <var>section</var> and <var>priority</var> are passed
9138 unchanged into the resulting <file>.changes</file> file.
9143 <sect1 id="pkg-dpkg-genchanges">
9145 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9150 This program is usually called by package-independent
9151 automatic building scripts such as
9152 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9157 It is usually called in the top level of a built source
9158 tree, and when invoked with no arguments will print out a
9159 straightforward <file>.changes</file> file based on the
9160 information in the source package's changelog and control
9161 file and the binary and source packages which should have
9167 <sect1 id="pkg-dpkg-parsechangelog">
9169 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9170 representation of a changelog
9174 This program is used internally by
9175 <prgn>dpkg-source</prgn> et al. It may also occasionally
9176 be useful in <file>debian/rules</file> and elsewhere. It
9177 parses a changelog, <file>debian/changelog</file> by default,
9178 and prints a control-file format representation of the
9179 information in it to standard output.
9183 <sect1 id="pkg-dpkg-architecture">
9185 <prgn>dpkg-architecture</prgn> - information about the build and
9190 This program can be used manually, but is also invoked by
9191 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9192 to set environment or make variables which specify the build and
9193 host architecture for the package building process.
9198 <sect id="pkg-sourcetree">
9199 <heading>The Debianised source tree</heading>
9202 The source archive scheme described later is intended to
9203 allow a Debianised source tree with some associated control
9204 information to be reproduced and transported easily. The
9205 Debianised source tree is a version of the original program
9206 with certain files added for the benefit of the
9207 Debianisation process, and with any other changes required
9208 made to the rest of the source code and installation
9213 The extra files created for Debian are in the subdirectory
9214 <file>debian</file> of the top level of the Debianised source
9215 tree. They are described below.
9218 <sect1 id="pkg-debianrules">
9219 <heading><file>debian/rules</file> - the main building script</heading>
9222 See <ref id="debianrules">.
9227 <sect1 id="pkg-dpkgchangelog">
9228 <heading><file>debian/changelog</file></heading>
9231 See <ref id="dpkgchangelog">.
9235 It is recommended that the entire changelog be encoded in the
9236 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9238 <url id="http://www.unicode.org/"
9239 name="Unicode">.<footnote>
9241 Support for Unicode, and specifically UTF-8, is
9242 steadily increasing among popular applications in
9243 Debian. For example, in unstable, GNOME 2 has
9244 excellent support (almost level 2) in almost all its
9245 applications; the big remaining one is gnome-terminal,
9246 of which one requires development versions in order to
9247 support UTF-8 (available in Debian experimental now if
9248 you want to play). I think that by the time sarge is
9249 released, UTF-8 support will start to hit critical
9252 I think it is fairly obvious that we need to
9253 eventually transition to UTF-8 for our package
9254 infrastructure; it is really the only sane charset in
9255 an international environment. Now, we can't switch to
9256 using UTF-8 for package control fields and the like
9257 until dpkg has better support, but one thing we can
9258 start doing today is requesting that Debian changelogs
9259 are UTF-8 encoded. At some point in time, we can start
9260 requiring them to do so.
9263 Checking for non-UTF8 characters in a changelog is
9264 trivial. Dump the file through
9265 <example>iconv -f utf-8 -t ucs-4</example>
9266 discard the output, and check the return
9267 value. If there are any characters in the stream
9268 which are invalid UTF-8 sequences, iconv will exit
9269 with an error code; and this will be the case for the
9270 vast majority of other character sets.
9275 <sect2><heading>Defining alternative changelog formats
9279 It is possible to use a different format to the standard
9280 one, by providing a parser for the format you wish to
9285 In order to have <tt>dpkg-parsechangelog</tt> run your
9286 parser, you must include a line within the last 40 lines
9287 of your file matching the Perl regular expression:
9288 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9289 parentheses should be the name of the format. For
9290 example, you might say:
9292 @@@ changelog-format: joebloggs @@@
9294 Changelog format names are non-empty strings of alphanumerics.
9298 If such a line exists then <tt>dpkg-parsechangelog</tt>
9299 will look for the parser as
9300 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9302 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9303 it is an error for it not to find it, or for it not to
9304 be an executable program. The default changelog format
9305 is <tt>dpkg</tt>, and a parser for it is provided with
9306 the <tt>dpkg</tt> package.
9310 The parser will be invoked with the changelog open on
9311 standard input at the start of the file. It should read
9312 the file (it may seek if it wishes) to determine the
9313 information required and return the parsed information
9314 to standard output in the form of a series of control
9315 fields in the standard format. By default it should
9316 return information about only the most recent version in
9317 the changelog; it should accept a
9318 <tt>-v<var>version</var></tt> option to return changes
9319 information from all versions present <em>strictly
9320 after</em> <var>version</var>, and it should then be an
9321 error for <var>version</var> not to be present in the
9327 <list compact="compact">
9328 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9329 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9330 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9331 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9332 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9333 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9334 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9339 If several versions are being returned (due to the use
9340 of <tt>-v</tt>), the urgency value should be of the
9341 highest urgency code listed at the start of any of the
9342 versions requested followed by the concatenated
9343 (space-separated) comments from all the versions
9344 requested; the maintainer, version, distribution and
9345 date should always be from the most recent version.
9349 For the format of the <tt>Changes</tt> field see
9350 <ref id="f-Changes">.
9354 If the changelog format which is being parsed always or
9355 almost always leaves a blank line between individual
9356 change notes these blank lines should be stripped out,
9357 so as to make the resulting output compact.
9361 If the changelog format does not contain date or package
9362 name information this information should be omitted from
9363 the output. The parser should not attempt to synthesise
9364 it or find it from other sources.
9368 If the changelog does not have the expected format the
9369 parser should exit with a nonzero exit status, rather
9370 than trying to muddle through and possibly generating
9375 A changelog parser may not interact with the user at
9381 <sect1 id="pkg-srcsubstvars">
9382 <heading><file>debian/substvars</file> and variable substitutions</heading>
9385 See <ref id="substvars">.
9391 <heading><file>debian/files</file></heading>
9394 See <ref id="debianfiles">.
9398 <sect1><heading><file>debian/tmp</file>
9402 This is the canonical temporary location for the
9403 construction of binary packages by the <tt>binary</tt>
9404 target. The directory <file>tmp</file> serves as the root of
9405 the filesystem tree as it is being constructed (for
9406 example, by using the package's upstream makefiles install
9407 targets and redirecting the output there), and it also
9408 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9409 id="pkg-bincreating">.
9413 If several binary packages are generated from the same
9414 source tree it is usual to use several
9415 <file>debian/tmp<var>something</var></file> directories, for
9416 example <file>tmp-a</file> or <file>tmp-doc</file>.
9420 Whatever <file>tmp</file> directories are created and used by
9421 <tt>binary</tt> must of course be removed by the
9422 <tt>clean</tt> target.</p></sect1>
9426 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9430 As it exists on the FTP site, a Debian source package
9431 consists of three related files. You must have the right
9432 versions of all three to be able to use them.
9437 <tag>Debian source control file - <tt>.dsc</tt></tag>
9439 This file is a control file used by <prgn>dpkg-source</prgn>
9440 to extract a source package.
9441 See <ref id="debiansourcecontrolfiles">.
9445 Original source archive -
9447 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9454 This is a compressed (with <tt>gzip -9</tt>)
9455 <prgn>tar</prgn> file containing the source code from
9456 the upstream authors of the program. The tarfile
9457 unpacks into a directory
9458 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9459 and does not contain files anywhere other than in
9460 there or in its subdirectories.</p>
9464 Debianisation diff -
9466 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9472 This is a unified context diff (<tt>diff -u</tt>)
9473 giving the changes which are required to turn the
9474 original source into the Debian source. These changes
9475 may only include editing and creating plain files.
9476 The permissions of files, the targets of symbolic
9477 links and the characteristics of special files or
9478 pipes may not be changed and no files may be removed
9483 All the directories in the diff must exist, except the
9484 <file>debian</file> subdirectory of the top of the source
9485 tree, which will be created by
9486 <prgn>dpkg-source</prgn> if necessary when unpacking.
9490 The <prgn>dpkg-source</prgn> program will
9491 automatically make the <file>debian/rules</file> file
9492 executable (see below).</p></item>
9497 If there is no original source code - for example, if the
9498 package is specially prepared for Debian or the Debian
9499 maintainer is the same as the upstream maintainer - the
9500 format is slightly different: then there is no diff, and the
9502 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9503 contains a directory
9504 <file><var>package</var>-<var>version</var></file>.
9509 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9512 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9513 Debian source package. However, if it is not available it
9514 is possible to unpack a Debian source archive as follows:
9515 <enumlist compact="compact">
9518 Untar the tarfile, which will create a <file>.orig</file>
9522 <p>Rename the <file>.orig</file> directory to
9523 <file><var>package</var>-<var>version</var></file>.</p>
9527 Create the subdirectory <file>debian</file> at the top of
9528 the source tree.</p>
9530 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9532 <item><p>Untar the tarfile again if you want a copy of the original
9533 source code alongside the Debianised version.</p>
9538 It is not possible to generate a valid Debian source archive
9539 without using <prgn>dpkg-source</prgn>. In particular,
9540 attempting to use <prgn>diff</prgn> directly to generate the
9541 <file>.diff.gz</file> file will not work.
9545 <heading>Restrictions on objects in source packages</heading>
9548 The source package may not contain any hard links
9550 This is not currently detected when building source
9551 packages, but only when extracting
9555 Hard links may be permitted at some point in the
9556 future, but would require a fair amount of
9558 </footnote>, device special files, sockets or setuid or
9561 Setgid directories are allowed.
9566 The source packaging tools manage the changes between the
9567 original and Debianised source using <prgn>diff</prgn> and
9568 <prgn>patch</prgn>. Turning the original source tree as
9569 included in the <file>.orig.tar.gz</file> into the debianised
9570 source must not involve any changes which cannot be
9571 handled by these tools. Problematic changes which cause
9572 <prgn>dpkg-source</prgn> to halt with an error when
9573 building the source package are:
9574 <list compact="compact">
9575 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9577 <item><p>Changing the targets of symbolic links.</p>
9579 <item><p>Creating directories, other than <file>debian</file>.</p>
9581 <item><p>Changes to the contents of binary files.</p></item>
9582 </list> Changes which cause <prgn>dpkg-source</prgn> to
9583 print a warning but continue anyway are:
9584 <list compact="compact">
9587 Removing files, directories or symlinks.
9589 Renaming a file is not treated specially - it is
9590 seen as the removal of the old file (which
9591 generates a warning, but is otherwise ignored),
9592 and the creation of the new one.
9598 Changed text files which are missing the usual final
9599 newline (either in the original or the modified
9604 Changes which are not represented, but which are not detected by
9605 <prgn>dpkg-source</prgn>, are:
9606 <list compact="compact">
9607 <item><p>Changing the permissions of files (other than
9608 <file>debian/rules</file>) and directories.</p></item>
9613 The <file>debian</file> directory and <file>debian/rules</file>
9614 are handled specially by <prgn>dpkg-source</prgn> - before
9615 applying the changes it will create the <file>debian</file>
9616 directory, and afterwards it will make
9617 <file>debian/rules</file> world-exectuable.
9623 <appendix id="pkg-controlfields">
9624 <heading>Control files and their fields (from old Packaging Manual)</heading>
9627 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9628 data in a common format, known as control files. Binary and
9629 source packages have control data as do the <file>.changes</file>
9630 files which control the installation of uploaded files, and
9631 <prgn>dpkg</prgn>'s internal databases are in a similar
9636 <heading>Syntax of control files</heading>
9639 See <ref id="controlsyntax">.
9643 It is important to note that there are several fields which
9644 are optional as far as <prgn>dpkg</prgn> and the related
9645 tools are concerned, but which must appear in every Debian
9646 package, or whose omission may cause problems.
9651 <heading>List of fields</heading>
9654 See <ref id="controlfieldslist">.
9658 This section now contains only the fields that didn't belong
9659 to the Policy manual.
9662 <sect1 id="pkg-f-Filename">
9663 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9666 These fields in <tt>Packages</tt> files give the
9667 filename(s) of (the parts of) a package in the
9668 distribution directories, relative to the root of the
9669 Debian hierarchy. If the package has been split into
9670 several parts the parts are all listed in order, separated
9675 <sect1 id="pkg-f-Size">
9676 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9679 These fields in <file>Packages</file> files give the size (in
9680 bytes, expressed in decimal) and MD5 checksum of the
9681 file(s) which make(s) up a binary package in the
9682 distribution. If the package is split into several parts
9683 the values for the parts are listed in order, separated by
9688 <sect1 id="pkg-f-Status">
9689 <heading><tt>Status</tt></heading>
9692 This field in <prgn>dpkg</prgn>'s status file records
9693 whether the user wants a package installed, removed or
9694 left alone, whether it is broken (requiring
9695 reinstallation) or not and what its current state on the
9696 system is. Each of these pieces of information is a
9701 <sect1 id="pkg-f-Config-Version">
9702 <heading><tt>Config-Version</tt></heading>
9705 If a package is not installed or not configured, this
9706 field in <prgn>dpkg</prgn>'s status file records the last
9707 version of the package which was successfully
9712 <sect1 id="pkg-f-Conffiles">
9713 <heading><tt>Conffiles</tt></heading>
9716 This field in <prgn>dpkg</prgn>'s status file contains
9717 information about the automatically-managed configuration
9718 files held by a package. This field should <em>not</em>
9719 appear anywhere in a package!
9724 <heading>Obsolete fields</heading>
9727 These are still recognised by <prgn>dpkg</prgn> but should
9728 not appear anywhere any more.
9730 <taglist compact="compact">
9732 <tag><tt>Revision</tt></tag>
9733 <tag><tt>Package-Revision</tt></tag>
9734 <tag><tt>Package_Revision</tt></tag>
9736 The Debian revision part of the package version was
9737 at one point in a separate control file field. This
9738 field went through several names.
9741 <tag><tt>Recommended</tt></tag>
9742 <item>Old name for <tt>Recommends</tt>.</item>
9744 <tag><tt>Optional</tt></tag>
9745 <item>Old name for <tt>Suggests</tt>.</item>
9747 <tag><tt>Class</tt></tag>
9748 <item>Old name for <tt>Priority</tt>.</item>
9757 <appendix id="pkg-conffiles">
9758 <heading>Configuration file handling (from old Packaging Manual)</heading>
9761 <prgn>dpkg</prgn> can do a certain amount of automatic
9762 handling of package configuration files.
9766 Whether this mechanism is appropriate depends on a number of
9767 factors, but basically there are two approaches to any
9768 particular configuration file.
9772 The easy method is to ship a best-effort configuration in the
9773 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9774 handle updates. If the user is unlikely to want to edit the
9775 file, but you need them to be able to without losing their
9776 changes, and a new package with a changed version of the file
9777 is only released infrequently, this is a good approach.
9781 The hard method is to build the configuration file from
9782 scratch in the <prgn>postinst</prgn> script, and to take the
9783 responsibility for fixing any mistakes made in earlier
9784 versions of the package automatically. This will be
9785 appropriate if the file is likely to need to be different on
9789 <sect><heading>Automatic handling of configuration files by
9794 A package may contain a control area file called
9795 <tt>conffiles</tt>. This file should be a list of filenames
9796 of configuration files needing automatic handling, separated
9797 by newlines. The filenames should be absolute pathnames,
9798 and the files referred to should actually exist in the
9803 When a package is upgraded <prgn>dpkg</prgn> will process
9804 the configuration files during the configuration stage,
9805 shortly before it runs the package's <prgn>postinst</prgn>
9810 For each file it checks to see whether the version of the
9811 file included in the package is the same as the one that was
9812 included in the last version of the package (the one that is
9813 being upgraded from); it also compares the version currently
9814 installed on the system with the one shipped with the last
9819 If neither the user nor the package maintainer has changed
9820 the file, it is left alone. If one or the other has changed
9821 their version, then the changed version is preferred - i.e.,
9822 if the user edits their file, but the package maintainer
9823 doesn't ship a different version, the user's changes will
9824 stay, silently, but if the maintainer ships a new version
9825 and the user hasn't edited it the new version will be
9826 installed (with an informative message). If both have
9827 changed their version the user is prompted about the problem
9828 and must resolve the differences themselves.
9832 The comparisons are done by calculating the MD5 message
9833 digests of the files, and storing the MD5 of the file as it
9834 was included in the most recent version of the package.
9838 When a package is installed for the first time
9839 <prgn>dpkg</prgn> will install the file that comes with it,
9840 unless that would mean overwriting a file already on the
9845 However, note that <prgn>dpkg</prgn> will <em>not</em>
9846 replace a conffile that was removed by the user (or by a
9847 script). This is necessary because with some programs a
9848 missing file produces an effect hard or impossible to
9849 achieve in another way, so that a missing file needs to be
9850 kept that way if the user did it.
9854 Note that a package should <em>not</em> modify a
9855 <prgn>dpkg</prgn>-handled conffile in its maintainer
9856 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9857 the user confusing and possibly dangerous options for
9858 conffile update when the package is upgraded.</p>
9861 <sect><heading>Fully-featured maintainer script configuration
9866 For files which contain site-specific information such as
9867 the hostname and networking details and so forth, it is
9868 better to create the file in the package's
9869 <prgn>postinst</prgn> script.
9873 This will typically involve examining the state of the rest
9874 of the system to determine values and other information, and
9875 may involve prompting the user for some information which
9876 can't be obtained some other way.
9880 When using this method there are a couple of important
9881 issues which should be considered:
9885 If you discover a bug in the program which generates the
9886 configuration file, or if the format of the file changes
9887 from one version to the next, you will have to arrange for
9888 the postinst script to do something sensible - usually this
9889 will mean editing the installed configuration file to remove
9890 the problem or change the syntax. You will have to do this
9891 very carefully, since the user may have changed the file,
9892 perhaps to fix the very problem that your script is trying
9893 to deal with - you will have to detect these situations and
9894 deal with them correctly.
9898 If you do go down this route it's probably a good idea to
9899 make the program that generates the configuration file(s) a
9900 separate program in <file>/usr/sbin</file>, by convention called
9901 <file><var>package</var>config</file> and then run that if
9902 appropriate from the post-installation script. The
9903 <tt><var>package</var>config</tt> program should not
9904 unquestioningly overwrite an existing configuration - if its
9905 mode of operation is geared towards setting up a package for
9906 the first time (rather than any arbitrary reconfiguration
9907 later) you should have it check whether the configuration
9908 already exists, and require a <tt>--force</tt> flag to
9909 overwrite it.</p></sect>
9912 <appendix id="pkg-alternatives"><heading>Alternative versions of
9913 an interface - <prgn>update-alternatives</prgn> (from old
9918 When several packages all provide different versions of the
9919 same program or file it is useful to have the system select a
9920 default, but to allow the system administrator to change it
9921 and have their decisions respected.
9925 For example, there are several versions of the <prgn>vi</prgn>
9926 editor, and there is no reason to prevent all of them from
9927 being installed at once, each under their own name
9928 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9929 Nevertheless it is desirable to have the name <tt>vi</tt>
9930 refer to something, at least by default.
9934 If all the packages involved cooperate, this can be done with
9935 <prgn>update-alternatives</prgn>.
9939 Each package provides its own version under its own name, and
9940 calls <prgn>update-alternatives</prgn> in its postinst to
9941 register its version (and again in its prerm to deregister
9946 See the manpage <manref name="update-alternatives"
9947 section="8"> for details.
9951 If <prgn>update-alternatives</prgn> does not seem appropriate
9952 you may wish to consider using diversions instead.</p>
9955 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9956 package's version of a file (from old Packaging Manual)
9960 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9961 when it reinstalls the package it belongs to, and to have it
9962 put the file from the package somewhere else instead.
9966 This can be used locally to override a package's version of a
9967 file, or by one package to override another's version (or
9968 provide a wrapper for it).
9972 Before deciding to use a diversion, read <ref
9973 id="pkg-alternatives"> to see if you really want a diversion
9974 rather than several alternative versions of a program.
9978 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9979 and updated by a special program <prgn>dpkg-divert</prgn>.
9980 Please see <manref name="dpkg-divert" section="8"> for full
9981 details of its operation.
9985 When a package wishes to divert a file from another, it should
9986 call <prgn>dpkg-divert</prgn> in its preinst to add the
9987 diversion and rename the existing file. For example,
9988 supposing that a <prgn>smailwrapper</prgn> package wishes to
9989 install a wrapper around <file>/usr/sbin/smail</file>:
9991 if [ install = "$1" ]; then
9992 dpkg-divert --package smailwrapper --add --rename \
9993 --divert /usr/sbin/smail.real /usr/sbin/smail
9995 </example> Testing <tt>$1</tt> is necessary so that the script
9996 doesn't try to add the diversion again when
9997 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
9998 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
9999 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10000 get installed as the true version.
10004 The postrm has to do the reverse:
10006 if [ remove = "$1" ]; then
10007 dpkg-divert --package smailwrapper --remove --rename \
10008 --divert /usr/sbin/smail.real /usr/sbin/smail
10014 Do not attempt to divert a file which is vitally important for
10015 the system's operation - when using <prgn>dpkg-divert</prgn>
10016 there is a time, after it has been diverted but before
10017 <prgn>dpkg</prgn> has installed the new version, when the file
10018 does not exist.</p>
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