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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 date based portion of the version number
860 should be changed to the following format in such cases:
861 "19960501", "19961224". It is up to the maintainer whether
862 he/she wants to bother the upstream maintainer to change
863 the version numbers upstream, too.
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>.
1086 The procedure for updating the list is described in the preface
1093 <heading>Base system</heading>
1096 The <tt>base system</tt> is a minimum subset of the Debian
1097 GNU/Linux system that is installed before everything else
1098 on a new system. Thus, only very few packages are allowed
1099 to go into the <tt>base</tt> section to keep the required
1100 disk usage very small.
1104 Most of these packages will have the priority value
1105 <tt>required</tt> or at least <tt>important</tt>, and many
1106 of them will be tagged <tt>essential</tt> (see below).
1111 <heading>Essential packages</heading>
1114 Some packages are tagged <tt>essential</tt> for a system
1115 using the <tt>Essential</tt> control file field.
1116 The format of the <tt>Essential</tt> control field is
1117 described in <ref id="f-Essential">.
1121 Since these packages cannot be easily removed (one has to
1122 specify an extra <em>force option</em> to
1123 <prgn>dpkg</prgn> to do so), this flag must not be used
1124 unless absolutely necessary. A shared library package
1125 must not be tagged <tt>essential</tt>; dependencies will
1126 prevent its premature removal, and we need to be able to
1127 remove it when it has been superseded.
1131 Since dpkg will not prevent upgrading of other packages
1132 while an <tt>essential</tt> package is in an unconfigured
1133 state, all <tt>essential</tt> packages must supply all of
1134 their core functionality even when unconfigured. If the
1135 package cannot satisfy this requirement it must not be
1136 tagged as essential, and any packages depending on this
1137 package must instead have explicit dependency fields as
1142 You must not tag any packages <tt>essential</tt> before
1143 this has been discussed on the <tt>debian-devel</tt>
1144 mailing list and a consensus about doing that has been
1150 <heading>Tasks</heading>
1153 The Debian install process allows the user to choose from
1154 a number of common tasks which a Debian system can be used to
1155 perform. Selecting a task with <prgn>tasksel</prgn> causes
1156 a set of packages that are useful in performing that task to be
1161 This set of packages is all available packages which have the
1162 name of the selected task in the <tt>Task</tt> field of their
1163 control file. The format of this field is a list of tasks,
1164 separated by commas.
1168 You should not tag any packages as belonging to a task
1169 before this has been discussed on the
1170 <em>debian-devel</em> mailing list and a consensus about
1171 doing that has been reached.
1175 For third parties (and historical reasons), tasksel also
1176 supports constructing tasks based on <em>task
1177 packages</em>. These are packages whose names begin with
1178 <em>task-</em>. Task packages should not be included in the
1183 <sect id="maintscripts">
1184 <heading>Maintainer Scripts</heading>
1187 The package installation scripts should avoid producing
1188 output which is unnecessary for the user to see and
1189 should rely on <prgn>dpkg</prgn> to stave off boredom on
1190 the part of a user installing many packages. This means,
1191 amongst other things, using the <tt>--quiet</tt> option on
1192 <prgn>install-info</prgn>.
1196 Errors which occur during the execution of an installation
1197 script must be checked and the installation must not
1198 continue after an error.
1202 Note that in general <ref id="scripts"> applies to package
1203 maintainer scripts, too.
1207 You should not use <prgn>dpkg-divert</prgn> on a file
1208 belonging to another package without consulting the
1209 maintainer of that package first.
1213 All packages which supply an instance of a common command
1214 name (or, in general, filename) should generally use
1215 <prgn>update-alternatives</prgn>, so that they may be
1216 installed together. If <prgn>update-alternatives</prgn>
1217 is not used, then each package must use
1218 <tt>Conflicts</tt> to ensure that other packages are
1219 de-installed. (In this case, it may be appropriate to
1220 specify a conflict against earlier versions of something
1221 that previously did not use
1222 <prgn>update-alternatives</prgn>; this is an exception to
1223 the usual rule that versioned conflicts should be
1227 <sect1 id="maintscriptprompt">
1228 <heading>Prompting in maintainer scripts</heading>
1230 Package maintainer scripts may prompt the user if
1231 necessary. Prompting should be done by communicating
1232 through a program, such as <prgn>debconf</prgn>, which
1233 conforms to the Debian Configuration management
1234 specification, version 2 or higher. Prompting the user by
1235 other means, such as by hand<footnote>
1236 From the Jargon file: by hand 2. By extension,
1237 writing code which does something in an explicit or
1238 low-level way for which a presupplied library
1239 (<em>debconf, in this instance</em>) routine ought
1240 to have been available.
1241 </footnote>, is now deprecated.
1245 The Debian Configuration management specification is included
1246 in the <file>debconf_specification</file> files in the
1247 <package>debian-policy</package> package.
1248 It is also available from the Debian web mirrors at
1249 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1250 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1254 Packages which use the Debian Configuration management
1255 specification may contain an additional
1256 <prgn>config</prgn> script and a <tt>templates</tt>
1257 file in their control archive<footnote>
1258 The control.tar.gz inside the .deb.
1259 See <manref name="deb" section="5">.
1261 The <prgn>config</prgn> script might be run before the
1262 <prgn>preinst</prgn> script, and before the package is unpacked
1263 or any of its dependencies or pre-dependancies are satisfied.
1264 Therefore it must work using only the tools present in
1265 <em>essential</em> packages.<footnote>
1266 <package>Debconf</package> or another tool that
1267 implements the Debian Configuration management
1268 specification will also be installed, and any
1269 versioned dependencies on it will be satisfied
1270 before preconfiguration begins.
1275 Packages should try to minimize the amount of prompting
1276 they need to do, and they should ensure that the user
1277 will only ever be asked each question once. This means
1278 that packages should try to use appropriate shared
1279 configuration files (such as <file>/etc/papersize</file> and
1280 <file>/etc/news/server</file>), and shared
1281 <package>debconf</package> variables rather than each
1282 prompting for their own list of required pieces of
1287 It also means that an upgrade should not ask the same
1288 questions again, unless the user has used
1289 <tt>dpkg --purge</tt> to remove the package's configuration.
1290 The answers to configuration questions should be stored in an
1291 appropriate place in <file>/etc</file> so that the user can
1292 modify them, and how this has been done should be
1297 If a package has a vitally important piece of
1298 information to pass to the user (such as "don't run me
1299 as I am, you must edit the following configuration files
1300 first or you risk your system emitting badly-formatted
1301 messages"), it should display this in the
1302 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1303 prompt the user to hit return to acknowledge the
1304 message. Copyright messages do not count as vitally
1305 important (they belong in
1306 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1307 neither do instructions on how to use a program (these
1308 should be in on-line documentation, where all the users
1313 Any necessary prompting should almost always be confined
1314 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1315 script. If it is done in the <prgn>postinst</prgn>, it
1316 should be protected with a conditional so that
1317 unnecessary prompting doesn't happen if a package's
1318 installation fails and the <prgn>postinst</prgn> is
1319 called with <tt>abort-upgrade</tt>,
1320 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1330 <heading>Source packages</heading>
1332 <sect id="standardsversion">
1333 <heading>Standards conformance</heading>
1336 Source packages should specify the most recent version number
1337 of this policy document with which your package complied
1338 when it was last updated.
1342 This information may be used to file bug reports
1343 automatically if your package becomes too much out of date.
1347 The version is specified in the <tt>Standards-Version</tt>
1349 The format of the <tt>Standards-Version</tt> field is
1350 described in <ref id="f-Standards-Version">.
1354 You should regularly, and especially if your package has
1355 become out of date, check for the newest Policy Manual
1356 available and update your package, if necessary. When your
1357 package complies with the new standards you should update the
1358 <tt>Standards-Version</tt> source package field and
1359 release it.<footnote>
1360 See the file <file>upgrading-checklist</file> for
1361 information about policy which has changed between
1362 different versions of this document.
1368 <sect id="pkg-relations">
1369 <heading>Package relationships</heading>
1372 Source packages should specify which binary packages they
1373 require to be installed or not to be installed in order to
1374 build correctly. For example, if building a package
1375 requires a certain compiler, then the compiler should be
1376 specified as a build-time dependency.
1380 It is not necessary to explicitly specify build-time
1381 relationships on a minimal set of packages that are always
1382 needed to compile, link and put in a Debian package a
1383 standard "Hello World!" program written in C or C++. The
1384 required packages are called <em>build-essential</em>, and
1385 an informational list can be found in
1386 <file>/usr/share/doc/build-essential/list</file> (which is
1387 contained in the <tt>build-essential</tt>
1390 <list compact="compact">
1392 This allows maintaining the list separately
1393 from the policy documents (the list does not
1394 need the kind of control that the policy
1398 Having a separate package allows one to install
1399 the build-essential packages on a machine, as
1400 well as allowing other packages such as tasks to
1401 require installation of the build-essential
1402 packages using the depends relation.
1405 The separate package allows bug reports against
1406 the list to be categorized separately from
1407 the policy management process in the BTS.
1414 When specifying the set of build-time dependencies, one
1415 should list only those packages explicitly required by the
1416 build. It is not necessary to list packages which are
1417 required merely because some other package in the list of
1418 build-time dependencies depends on them.<footnote>
1419 The reason for this is that dependencies change, and
1420 you should list all those packages, and <em>only</em>
1421 those packages that <em>you</em> need directly. What
1422 others need is their business. For example, if you
1423 only link against <file>libimlib</file>, you will need to
1424 build-depend on <package>libimlib2-dev</package> but
1425 not against any <tt>libjpeg*</tt> packages, even
1426 though <tt>libimlib2-dev</tt> currently depends on
1427 them: installation of <package>libimlib2-dev</package>
1428 will automatically ensure that all of its run-time
1429 dependencies are satisfied.
1434 If build-time dependencies are specified, it must be
1435 possible to build the package and produce working binaries
1436 on a system with only essential and build-essential
1437 packages installed and also those required to satisfy the
1438 build-time relationships (including any implied
1439 relationships). In particular, this means that version
1440 clauses should be used rigorously in build-time
1441 relationships so that one cannot produce bad or
1442 inconsistently configured packages when the relationships
1443 are properly satisfied.
1447 <ref id="relationships"> explains the technical details.
1452 <heading>Changes to the upstream sources</heading>
1455 If changes to the source code are made that are not
1456 specific to the needs of the Debian system, they should be
1457 sent to the upstream authors in whatever form they prefer
1458 so as to be included in the upstream version of the
1463 If you need to configure the package differently for
1464 Debian or for Linux, and the upstream source doesn't
1465 provide a way to do so, you should add such configuration
1466 facilities (for example, a new <prgn>autoconf</prgn> test
1467 or <tt>#define</tt>) and send the patch to the upstream
1468 authors, with the default set to the way they originally
1469 had it. You can then easily override the default in your
1470 <file>debian/rules</file> or wherever is appropriate.
1474 You should make sure that the <prgn>configure</prgn> utility
1475 detects the correct architecture specification string
1476 (refer to <ref id="arch-spec"> for details).
1480 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1481 <prgn>configure</prgn> scripts are used, you should edit the
1482 <file>.in</file> files rather than editing the
1483 <prgn>Makefile</prgn> directly. This allows the user to
1484 reconfigure the package if necessary. You should
1485 <em>not</em> configure the package and edit the generated
1486 <prgn>Makefile</prgn>! This makes it impossible for someone
1487 else to later reconfigure the package without losing the
1493 <sect id="dpkgchangelog">
1494 <heading>Debian changelog: <file>debian/changelog</file></heading>
1497 Changes in the Debian version of the package should be
1498 briefly explained in the Debian changelog file
1499 <file>debian/changelog</file>. This includes modifications
1500 made in the Debian package compared to the upstream one
1501 as well as other changes and updates to the package.
1503 Although there is nothing stopping an author who is also
1504 the Debian maintainer from using this changelog for all
1505 their changes, it will have to be renamed if the Debian
1506 and upstream maintainers become different people. In such
1507 a case, however, it might be better to maintain the package
1508 as a non-native package.
1513 Mistakes in changelogs are usually best rectified by making
1514 a new changelog entry rather than "rewriting history" by
1515 editing old changelog entries.
1519 The format of the <file>debian/changelog</file> allows the
1520 package building tools to discover which version of the package
1521 is being built and find out other release-specific information.
1525 That format is a series of entries like this:
1527 <example compact="compact">
1528 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1530 [optional blank line(s), stripped]
1532 * <var>change details</var>
1533 <var>more change details</var>
1535 [blank line(s), included in output of dpkg-parsechangelog]
1537 * <var>even more change details</var>
1539 [optional blank line(s), stripped]
1541 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1546 <var>package</var> and <var>version</var> are the source
1547 package name and version number.
1551 <var>distribution(s)</var> lists the distributions where
1552 this version should be installed when it is uploaded - it
1553 is copied to the <tt>Distribution</tt> field in the
1554 <file>.changes</file> file. See <ref id="f-Distribution">.
1558 <var>urgency</var> is the value for the <tt>Urgency</tt>
1559 field in the <file>.changes</file> file for the upload
1560 (see <ref id="f-Urgency">). It is not possible to specify
1561 an urgency containing commas; commas are used to separate
1562 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1563 <prgn>dpkg</prgn> changelog format (though there is
1564 currently only one useful <var>keyword</var>,
1565 <tt>urgency</tt>).<footnote>
1566 Recognised urgency values are <tt>low</tt>,
1567 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1568 They have an effect on how quickly a package will be
1569 considered for inclusion into the <tt>testing</tt>
1570 distribution, and give an indication of the importance
1571 of any fixes included in this upload.
1576 The change details may in fact be any series of lines
1577 starting with at least two spaces, but conventionally each
1578 change starts with an asterisk and a separating space and
1579 continuation lines are indented so as to bring them in
1580 line with the start of the text above. Blank lines may be
1581 used here to separate groups of changes, if desired.
1585 If this upload resolves bugs recorded in the Bug Tracking
1586 System (BTS), they may be automatically closed on the
1587 inclusion of this package into the Debian archive by
1588 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1589 in the change details.<footnote>
1590 To be precise, the string should match the following
1591 Perl regular expression:
1593 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1595 Then all of the bug numbers listed will be closed by the
1596 archive maintenance script (<prgn>katie</prgn>), or in
1597 the case of an NMU, marked as fixed.
1599 This information is conveyed via the <tt>Closes</tt> field
1600 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1604 The maintainer name and email address used in the changelog
1605 should be the details of the person uploading <em>this</em>
1606 version. They are <em>not</em> necessarily those of the
1607 usual package maintainer. The information here will be
1608 copied to the <tt>Changed-By</tt> field in the
1609 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1610 and then later used to send an acknowledgement when the
1611 upload has been installed.
1615 The <var>date</var> should be in RFC822 format<footnote>
1616 This is generated by the <prgn>822-date</prgn>
1618 </footnote>; it should include the time zone specified
1619 numerically, with the time zone name or abbreviation
1620 optionally present as a comment in parentheses.
1624 The first "title" line with the package name should start
1625 at the left hand margin; the "trailer" line with the
1626 maintainer and date details should be preceded by exactly
1627 one space. The maintainer details and the date must be
1628 separated by exactly two spaces.
1632 For more information on placement of the changelog files
1633 within binary packages, please see <ref id="changelogs">.
1636 <sect1><heading>Alternative changelog formats</heading>
1639 In non-experimental packages you must use a format for
1640 <file>debian/changelog</file> which is supported by the most
1641 recent released version of <prgn>dpkg</prgn>.
1645 It is possible to use a format different from the standard
1646 one by providing a changelog parser for the format you wish
1647 to use. The parser must have an API compatible with that
1648 expected by <prgn>dpkg-genchanges</prgn> and
1649 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1652 If there is general interest in the new format, you should
1653 contact the <package>dpkg</package> maintainer to have the
1654 parser script for it included in the <prgn>dpkg</prgn>
1655 package. (You will need to agree that the parser and its
1656 man page may be distributed under the GNU GPL, just as the rest
1657 of <prgn>dpkg</prgn> is.)
1664 <heading>Error trapping in makefiles</heading>
1667 When <prgn>make</prgn> invokes a command in a makefile
1668 (including your package's upstream makefiles and
1669 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1670 means that <prgn>sh</prgn>'s usual bad error handling
1671 properties apply: if you include a miniature script as one
1672 of the commands in your makefile you'll find that if you
1673 don't do anything about it then errors are not detected
1674 and <prgn>make</prgn> will blithely continue after
1679 Every time you put more than one shell command (this
1680 includes using a loop) in a makefile command you
1681 must make sure that errors are trapped. For
1682 simple compound commands, such as changing directory and
1683 then running a program, using <tt>&&</tt> rather
1684 than semicolon as a command separator is sufficient. For
1685 more complex commands including most loops and
1686 conditionals you should include a separate <tt>set -e</tt>
1687 command at the start of every makefile command that's
1688 actually one of these miniature shell scripts.
1692 <sect id="timestamps">
1693 <heading>Time Stamps</heading>
1695 Maintainers should preserve the modification times of the
1696 upstream source files in a package, as far as is reasonably
1698 The rationale is that there is some information conveyed
1699 by knowing the age of the file, for example, you could
1700 recognize that some documentation is very old by looking
1701 at the modification time, so it would be nice if the
1702 modification time of the upstream source would be
1708 <sect id="restrictions">
1709 <heading>Restrictions on objects in source packages</heading>
1712 The source package may not contain any hard links<footnote>
1714 This is not currently detected when building source
1715 packages, but only when extracting
1719 Hard links may be permitted at some point in the
1720 future, but would require a fair amount of
1723 </footnote>, device special files, sockets or setuid or
1724 setgid files.<footnote>
1725 Setgid directories are allowed.
1730 <sect id="debianrules">
1731 <heading>Main building script: <file>debian/rules</file></heading>
1734 This file must be an executable makefile, and contains the
1735 package-specific recipes for compiling the package and
1736 building binary package(s) from the source.
1740 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1741 so that it can be invoked by saying its name rather than
1742 invoking <prgn>make</prgn> explicitly.
1746 Since an interactive <file>debian/rules</file> script makes it
1747 impossible to auto-compile that package and also makes it
1748 hard for other people to reproduce the same binary
1749 package, all <em>required targets</em> MUST be
1750 non-interactive. At a minimum, required targets are the
1751 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1752 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1753 <em>binary-indep</em>, and <em>build</em>. It also follows
1754 that any target that these targets depend on must also be
1759 The targets are as follows (required unless stated otherwise):
1761 <tag><tt>build</tt></tag>
1764 The <tt>build</tt> target should perform all the
1765 configuration and compilation of the package.
1766 If a package has an interactive pre-build
1767 configuration routine, the Debianized source package
1768 must either be built after this has taken place (so
1769 that the binary package can be built without rerunning
1770 the configuration) or the configuration routine
1771 modified to become non-interactive. (The latter is
1772 preferable if there are architecture-specific features
1773 detected by the configuration routine.)
1777 For some packages, notably ones where the same
1778 source tree is compiled in different ways to produce
1779 two binary packages, the <tt>build</tt> target
1780 does not make much sense. For these packages it is
1781 good enough to provide two (or more) targets
1782 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1783 for each of the ways of building the package, and a
1784 <tt>build</tt> target that does nothing. The
1785 <tt>binary</tt> target will have to build the
1786 package in each of the possible ways and make the
1787 binary package out of each.
1791 The <tt>build</tt> target must not do anything
1792 that might require root privilege.
1796 The <tt>build</tt> target may need to run the
1797 <tt>clean</tt> target first - see below.
1801 When a package has a configuration and build routine
1802 which takes a long time, or when the makefiles are
1803 poorly designed, or when <tt>build</tt> needs to
1804 run <tt>clean</tt> first, it is a good idea to
1805 <tt>touch build</tt> when the build process is
1806 complete. This will ensure that if <tt>debian/rules
1807 build</tt> is run again it will not rebuild the whole
1809 Another common way to do this is for <tt>build</tt>
1810 to depend on <prgn>build-stamp</prgn> and to do
1811 nothing else, and for the <prgn>build-stamp</prgn>
1812 target to do the building and to <tt>touch
1813 build-stamp</tt> on completion. This is
1814 especially useful if the build routine creates a
1815 file or directory called <tt>build</tt>; in such a
1816 case, <tt>build</tt> will need to be listed as
1817 a phony target (i.e., as a dependency of the
1818 <tt>.PHONY</tt> target). See the documentation of
1819 <prgn>make</prgn> for more information on phony
1825 <tag><tt>build-arch</tt> (optional),
1826 <tt>build-indep</tt> (optional)
1830 A package may also provide both of the targets
1831 <tt>build-arch</tt> and <tt>build-indep</tt>.
1832 The <tt>build-arch</tt> target, if provided, should
1833 perform all the configuration and compilation required
1834 for producing all architecture-dependant binary packages
1835 (those packages for which the body of the
1836 <tt>Architecture</tt> field in <tt>debian/control</tt>
1837 is not <tt>all</tt>).
1838 Similarly, the <tt>build-indep</tt> target, if
1839 provided, should perform all the configuration and
1840 compilation required for producing all
1841 architecture-independent binary packages
1842 (those packages for which the body of the
1843 <tt>Architecture</tt> field in <tt>debian/control</tt>
1845 The <tt>build</tt> target should depend on those of the
1846 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1847 are provided in the rules file.
1851 If one or both of the targets <tt>build-arch</tt> and
1852 <tt>build-indep</tt> are not provided, then invoking
1853 <file>debian/rules</file> with one of the not-provided
1854 targets as arguments should produce a exit status code
1855 of 2. Usually this is provided automatically by make
1856 if the target is missing.
1860 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1861 must not do anything that might require root privilege.
1865 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1866 <tt>binary-indep</tt>
1870 The <tt>binary</tt> target must be all that is
1871 necessary for the user to build the binary package(s)
1872 produced from this source package. It is
1873 split into two parts: <prgn>binary-arch</prgn> builds
1874 the binary packages which are specific to a particular
1875 architecture, and <tt>binary-indep</tt> builds
1876 those which are not.
1879 <tt>binary</tt> may be (and commonly is) a target with
1880 no commands which simply depends on
1881 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1884 Both <tt>binary-*</tt> targets should depend on the
1885 <tt>build</tt> target, or on the appropriate
1886 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1887 provided, so that the package is built if it has not
1888 been already. It should then create the relevant
1889 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1890 make their control files and <prgn>dpkg-deb</prgn> to
1891 build them and place them in the parent of the top
1896 Both the <tt>binary-arch</tt> and
1897 <tt>binary-indep</tt> targets <em>must</em> exist.
1898 If one of them has nothing to do (which will always be
1899 the case if the source generates only a single binary
1900 package, whether architecture-dependent or not), it
1901 must still exist and must always succeed.
1905 The <tt>binary</tt> targets must be invoked as
1907 The <prgn>fakeroot</prgn> package often allows one
1908 to build a package correctly even without being
1914 <tag><tt>clean</tt></tag>
1917 This must undo any effects that the <tt>build</tt>
1918 and <tt>binary</tt> targets may have had, except
1919 that it should leave alone any output files created in
1920 the parent directory by a run of a <tt>binary</tt>
1925 If a <tt>build</tt> file is touched at the end of
1926 the <tt>build</tt> target, as suggested above, it
1927 should be removed as the first action that
1928 <tt>clean</tt> performs, so that running
1929 <tt>build</tt> again after an interrupted
1930 <tt>clean</tt> doesn't think that everything is
1935 The <tt>clean</tt> target may need to be
1936 invoked as root if <tt>binary</tt> has been
1937 invoked since the last <tt>clean</tt>, or if
1938 <tt>build</tt> has been invoked as root (since
1939 <tt>build</tt> may create directories, for
1944 <tag><tt>get-orig-source</tt> (optional)</tag>
1947 This target fetches the most recent version of the
1948 original source package from a canonical archive site
1949 (via FTP or WWW, for example), does any necessary
1950 rearrangement to turn it into the original source
1951 tar file format described below, and leaves it in the
1956 This target may be invoked in any directory, and
1957 should take care to clean up any temporary files it
1962 This target is optional, but providing it if
1963 possible is a good idea.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1997 specification string)
2000 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2001 <tt>DEB_*_GNU_TYPE</tt>)
2004 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2005 <tt>DEB_*_GNU_TYPE</tt>)
2007 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2008 the build machine or <tt>HOST</tt> for specification of the
2013 Backward compatibility can be provided in the rules file
2014 by setting the needed variables to suitable default
2015 values; please refer to the documentation of
2016 <prgn>dpkg-architecture</prgn> for details.
2020 It is important to understand that the <tt>DEB_*_ARCH</tt>
2021 string only determines which Debian architecture we are
2022 building on or for. It should not be used to get the CPU
2023 or system information; the GNU style variables should be
2028 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2029 <sect id="substvars">
2030 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2033 When <prgn>dpkg-gencontrol</prgn>,
2034 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2035 generate control files they perform variable substitutions
2036 on their output just before writing it. Variable
2037 substitutions have the form <tt>${<var>variable</var>}</tt>.
2038 The optional file <file>debian/substvars</file> contains
2039 variable substitutions to be used; variables can also be set
2040 directly from <file>debian/rules</file> using the <tt>-V</tt>
2041 option to the source packaging commands, and certain
2042 predefined variables are also available.
2046 The <file>debian/substvars</file> file is usually generated and
2047 modified dynamically by <file>debian/rules</file> targets, in
2048 which case it must be removed by the <tt>clean</tt> target.
2052 See <manref name="dpkg-source" section="1"> for full
2053 details about source variable substitutions, including the
2054 format of <file>debian/substvars</file>.</p>
2057 <sect id="debianfiles">
2058 <heading>Generated files list: <file>debian/files</file></heading>
2061 This file is not a permanent part of the source tree; it
2062 is used while building packages to record which files are
2063 being generated. <prgn>dpkg-genchanges</prgn> uses it
2064 when it generates a <file>.changes</file> file.
2068 It should not exist in a shipped source package, and so it
2069 (and any backup files or temporary files such as
2070 <file>files.new</file><footnote>
2071 <file>files.new</file> is used as a temporary file by
2072 <prgn>dpkg-gencontrol</prgn> and
2073 <prgn>dpkg-distaddfile</prgn> - they write a new
2074 version of <tt>files</tt> here before renaming it,
2075 to avoid leaving a corrupted copy if an error
2077 </footnote>) should be removed by the
2078 <tt>clean</tt> target. It may also be wise to
2079 ensure a fresh start by emptying or removing it at the
2080 start of the <tt>binary</tt> target.
2084 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2085 package, it adds an entry to <file>debian/files</file> for the
2086 <file>.deb</file> file that will be created when <tt>dpkg-deb
2087 --build</tt> is run for that binary package. So for most
2088 packages all that needs to be done with this file is to
2089 delete it in the <tt>clean</tt> target.
2093 If a package upload includes files besides the source
2094 package and any binary packages whose control files were
2095 made with <prgn>dpkg-gencontrol</prgn> then they should be
2096 placed in the parent of the package's top-level directory
2097 and <prgn>dpkg-distaddfile</prgn> should be called to add
2098 the file to the list in <file>debian/files</file>.</p>
2104 <chapt id="controlfields">
2105 <heading>Control files and their fields</heading>
2108 The package management system manipulates data represented in
2109 a common format, known as <em>control data</em>, stored in
2110 <em>control files</em>.
2111 Control files are used for source packages, binary packages and
2112 the <file>.changes</file> files which control the installation
2113 of uploaded files<footnote>
2114 <prgn>dpkg</prgn>'s internal databases are in a similar
2119 <sect id="controlsyntax">
2120 <heading>Syntax of control files</heading>
2123 A control file consists of one or more paragraphs of
2125 The paragraphs are also sometimes referred to as stanzas.
2127 The paragraphs are separated by blank lines. Some control
2128 files allow only one paragraph; others allow several, in
2129 which case each paragraph usually refers to a different
2130 package. (For example, in source packages, the first
2131 paragraph refers to the source package, and later paragraphs
2132 refer to binary packages generated from the source.)
2136 Each paragraph consists of a series of data fields; each
2137 field consists of the field name, followed by a colon and
2138 then the data/value associated with that field. It ends at
2139 the end of the line. Horizontal whitespace (spaces and
2140 tabs) may occur immediately before or after the value and is
2141 ignored there; it is conventional to put a single space
2142 after the colon. For example, a field might be:
2143 <example compact="compact">
2146 the field name is <tt>Package</tt> and the field value
2151 Some fields' values may span several lines; in this case
2152 each continuation line must start with a space or a tab.
2153 Any trailing spaces or tabs at the end of individual
2154 lines of a field value are ignored.
2158 Except where otherwise stated, only a single line of data is
2159 allowed and whitespace is not significant in a field body.
2160 Whitespace must not appear inside names (of packages,
2161 architectures, files or anything else) or version numbers,
2162 or between the characters of multi-character version
2167 Field names are not case-sensitive, but it is usual to
2168 capitalize the field names using mixed case as shown below.
2172 Blank lines, or lines consisting only of spaces and tabs,
2173 are not allowed within field values or between fields - that
2174 would mean a new paragraph.
2179 <sect id="sourcecontrolfiles">
2180 <heading>Source package control files -- <file>debian/control</file></heading>
2183 The <file>debian/control</file> file contains the most vital
2184 (and version-independent) information about the source package
2185 and about the binary packages it creates.
2189 The first paragraph of the control file contains information about
2190 the source package in general. The subsequent sets each describe a
2191 binary package that the source tree builds.
2195 The fields in the general paragraph (the first one, for the source
2198 <list compact="compact">
2199 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2200 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2201 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2202 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2203 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2204 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2205 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2210 The fields in the binary package paragraphs are:
2212 <list compact="compact">
2213 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2214 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2215 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2216 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2217 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2218 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2219 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2224 The syntax and semantics of the fields are described below.
2230 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2231 generate control files for binary packages (see below), by
2232 <prgn>dpkg-genchanges</prgn> to generate the
2233 <tt>.changes</tt> file to accompany the upload, and by
2234 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2235 source control file as part of a source archive.
2239 The fields here may contain variable references - their
2240 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2241 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2242 when they generate output control files.
2243 See <ref id="substvars"> for details.
2248 <sect id="binarycontrolfiles">
2249 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2252 The <file>DEBIAN/control</file> file contains the most vital
2253 (and version-dependent) information about a binary package.
2257 The fields in this file are:
2259 <list compact="compact">
2260 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2261 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2262 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2263 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2264 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2265 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2266 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2267 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2268 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2269 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2275 <sect id="debiansourcecontrolfiles">
2276 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2279 This file contains a series of fields, identified and
2280 separated just like the fields in the control file of
2281 a binary package. The fields are listed below; their
2282 syntax is described above, in <ref id="pkg-controlfields">.
2284 <list compact="compact">
2285 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2286 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2287 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2288 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2289 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2290 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2291 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2292 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2293 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2294 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2299 The source package control file is generated by
2300 <prgn>dpkg-source</prgn> when it builds the source
2301 archive, from other files in the source package,
2302 described above. When unpacking, it is checked against
2303 the files and directories in the other parts of the
2309 <sect id="debianchangesfiles">
2310 <heading>Debian changes files -- <file>.changes</file></heading>
2313 The .changes files are used by the Debian archive maintenance
2314 software to process updates to packages. They contain one
2315 paragraph which contains information from the
2316 <tt>debian/control</tt> file and other data about the
2317 source package gathered via <tt>debian/changelog</tt>
2318 and <tt>debian/rules</tt>.
2322 The fields in this file are:
2324 <list compact="compact">
2325 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2326 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2327 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2328 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2329 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2330 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2333 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2335 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2337 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2343 <sect id="controlfieldslist">
2344 <heading>List of fields</heading>
2346 <sect1 id="f-Source">
2347 <heading><tt>Source</tt></heading>
2350 This field identifies the source package name.
2354 In a main source control information, a <file>.changes</file>
2355 or a <file>.dsc</file> file this may contain only the name
2356 of the source package.
2360 In the control file of a binary package it may be followed
2361 by a version number in parentheses<footnote>
2362 It is customary to leave a space after the package name
2363 if a version number is specified.
2365 This version number may be omitted (and is, by
2366 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2367 the <tt>Version</tt> field of the binary package in
2368 question. The field itself may be omitted from a binary
2369 package control file when the source package has the same
2370 name and version as the binary package.
2374 <sect1 id="f-Maintainer">
2375 <heading><tt>Maintainer</tt></heading>
2378 The package maintainer's name and email address. The name
2379 should come first, then the email address inside angle
2380 brackets <tt><></tt> (in RFC822 format).
2384 If the maintainer's name contains a full stop then the
2385 whole field will not work directly as an email address due
2386 to a misfeature in the syntax specified in RFC822; a
2387 program using this field as an address must check for this
2388 and correct the problem if necessary (for example by
2389 putting the name in round brackets and moving it to the
2390 end, and bringing the email address forward).
2394 <sect1 id="f-Uploaders">
2395 <heading><tt>Uploaders</tt></heading>
2398 List of the names and email addresses of
2399 co-maintaintainers of the package, if any. If the package
2400 has other maintainers beside the one named in the <qref
2401 id="f-Maintainer">Maintainer field</qref>, they their
2402 names and email addresses should be listed here. The
2403 format is the same as that of the Maintainer tag, and
2404 multiple entries should be comma separated. This is an
2409 <sect1 id="f-Changed-By">
2410 <heading><tt>Changed-By</tt></heading>
2413 The name and email address of the person who changed the
2414 said package. Usually the name of the maintainer.
2415 All the rules for the Maintainer field apply here, too.
2419 <sect1 id="f-Section">
2420 <heading><tt>Section</tt></heading>
2423 This field specifies an application area into which the package
2424 has been classified. See <ref id="subsections">.
2428 When it appears in the <file>debian/control</file> file,
2429 it gives the value for the subfield of the same name in
2430 the <tt>Files</tt> field of the <file>.changes</file> file.
2431 It also gives the default for the same field in the binary
2436 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2437 field in the control file of a binary package - use the
2438 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2442 <sect1 id="f-Priority">
2443 <heading><tt>Priority</tt></heading>
2446 This field represents how important that it is that the user
2447 have the package installed. See <ref id="priorities">.
2451 When it appears in the <file>debian/control</file> file,
2452 it gives the value for the subfield of the same name in
2453 the <tt>Files</tt> field of the <file>.changes</file> file.
2454 It also gives the default for the same field in the binary
2459 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2460 field in the control file of a binary package - use the
2461 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2465 <sect1 id="f-Package">
2466 <heading><tt>Package</tt></heading>
2469 The name of the binary package.
2473 Package names must consist only of lower case letters
2474 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2475 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2476 They must be at least two characters long and must start
2477 with an alphanumeric character.
2481 <sect1 id="f-Architecture">
2482 <heading><tt>Architecture</tt></heading>
2485 Depending on context and the control file used, the
2486 <tt>Architecture</tt> field can include the following sets of
2489 <item>A unique single word identifying a Debian machine
2490 architecture, see <ref id="arch-spec">.
2491 <item><tt>all</tt>, which indicates an
2492 architecture-independent package.
2493 <item><tt>any</tt>, which indicates a package available
2494 for building on any architecture.
2495 <item><tt>source</tt>, which indicates a source package.
2500 In the main <file>debian/control</file> file in the source
2501 package, or in the source package control file
2502 <file>.dsc</file>, one may specify a list of architectures
2503 separated by spaces, or the special values <tt>any</tt> or
2508 Specifying <tt>any</tt> indicates that the source package
2509 isn't dependent on any particular architecture and should
2510 compile fine on any one. The produced binary package(s)
2511 will be specific to whatever the current build architecture
2513 This is the most often used setting, and is recommended
2514 for new packages that aren't <tt>Architecture: all</tt>.
2519 Specifying a list of architectures indicates that the source
2520 will build an architecture-dependent package, and will only
2521 work correctly on the listed architectures.<footnote>
2522 This is a setting used for a minority of cases where the
2523 program is not portable. Generally, it should not be used
2529 In a <file>.changes</file> file, the <tt>Architecture</tt>
2530 field lists the architecture(s) of the package(s)
2531 currently being uploaded. This will be a list; if the
2532 source for the package is also being uploaded, the special
2533 entry <tt>source</tt> is also present.
2537 See <ref id="debianrules"> for information how to get the
2538 architecture for the build process.
2542 <sect1 id="f-Essential">
2543 <heading><tt>Essential</tt></heading>
2546 This is a boolean field which may occur only in the
2547 control file of a binary package or in a per-package fields
2548 paragraph of a main source control data file.
2552 If set to <tt>yes</tt> then the package management system
2553 will refuse to remove the package (upgrading and replacing
2554 it is still possible). The other possible value is <tt>no</tt>,
2555 which is the same as not having the field at all.
2560 <heading>Package interrelationship fields:
2561 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2562 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2563 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2567 These fields describe the package's relationships with
2568 other packages. Their syntax and semantics are described
2569 in <ref id="relationships">.</p>
2572 <sect1 id="f-Standards-Version">
2573 <heading><tt>Standards-Version</tt></heading>
2576 The most recent version of the standards (the policy
2577 manual and associated texts) with which the package
2582 The version number has four components: major and minor
2583 version number and major and minor patch level. When the
2584 standards change in a way that requires every package to
2585 change the major number will be changed. Significant
2586 changes that will require work in many packages will be
2587 signaled by a change to the minor number. The major patch
2588 level will be changed for any change to the meaning of the
2589 standards, however small; the minor patch level will be
2590 changed when only cosmetic, typographical or other edits
2591 are made which neither change the meaning of the document
2592 nor affect the contents of packages.
2596 Thus only the first three components of the policy version
2597 are significant in the <em>Standards-Version</em> control
2598 field, and so either these three components or the all
2599 four components may be specified.<footnote>
2600 In the past, people specified the full version number
2601 in the Standards-Version field, for example "2.3.0.0".
2602 Since minor patch-level changes don't introduce new
2603 policy, it was thought it would be better to relax
2604 policy and only require the first 3 components to be
2605 specified, in this example "2.3.0". All four
2606 components may still be used if someone wishes to do so.
2612 <sect1 id="f-Version">
2613 <heading><tt>Version</tt></heading>
2616 The version number of a package. The format is:
2617 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2621 The three components here are:
2623 <tag><var>epoch</var></tag>
2626 This is a single (generally small) unsigned integer. It
2627 may be omitted, in which case zero is assumed. If it is
2628 omitted then the <var>upstream_version</var> may not
2633 It is provided to allow mistakes in the version numbers
2634 of older versions of a package, and also a package's
2635 previous version numbering schemes, to be left behind.
2639 <tag><var>upstream_version</var></tag>
2642 This is the main part of the version number. It is
2643 usually the version number of the original ("upstream")
2644 package from which the <file>.deb</file> file has been made,
2645 if this is applicable. Usually this will be in the same
2646 format as that specified by the upstream author(s);
2647 however, it may need to be reformatted to fit into the
2648 package management system's format and comparison
2653 The comparison behavior of the package management system
2654 with respect to the <var>upstream_version</var> is
2655 described below. The <var>upstream_version</var>
2656 portion of the version number is mandatory.
2660 The <var>upstream_version</var> may contain only
2661 alphanumerics<footnote>
2662 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2664 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2665 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2666 start with a digit. If there is no
2667 <var>debian_revision</var> then hyphens are not allowed;
2668 if there is no <var>epoch</var> then colons are not
2673 <tag><var>debian_revision</var></tag>
2676 This part of the version number specifies the version of
2677 the Debian package based on the upstream version. It
2678 may contain only alphanumerics and the characters
2679 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2680 compared in the same way as the
2681 <var>upstream_version</var> is.
2685 It is optional; if it isn't present then the
2686 <var>upstream_version</var> may not contain a hyphen.
2687 This format represents the case where a piece of
2688 software was written specifically to be turned into a
2689 Debian package, and so there is only one "debianization"
2690 of it and therefore no revision indication is required.
2694 It is conventional to restart the
2695 <var>debian_revision</var> at <tt>1</tt> each time the
2696 <var>upstream_version</var> is increased.
2700 The package management system will break the version
2701 number apart at the last hyphen in the string (if there
2702 is one) to determine the <var>upstream_version</var> and
2703 <var>debian_revision</var>. The absence of a
2704 <var>debian_revision</var> compares earlier than the
2705 presence of one (but note that the
2706 <var>debian_revision</var> is the least significant part
2707 of the version number).
2714 The <var>upstream_version</var> and <var>debian_revision</var>
2715 parts are compared by the package management system using the
2720 The strings are compared from left to right.
2724 First the initial part of each string consisting entirely of
2725 non-digit characters is determined. These two parts (one of
2726 which may be empty) are compared lexically. If a difference
2727 is found it is returned. The lexical comparison is a
2728 comparison of ASCII values modified so that all the letters
2729 sort earlier than all the non-letters.
2733 Then the initial part of the remainder of each string which
2734 consists entirely of digit characters is determined. The
2735 numerical values of these two parts are compared, and any
2736 difference found is returned as the result of the comparison.
2737 For these purposes an empty string (which can only occur at
2738 the end of one or both version strings being compared) counts
2743 These two steps (comparing and removing initial non-digit
2744 strings and initial digit strings) are repeated until a
2745 difference is found or both strings are exhausted.
2749 Note that the purpose of epochs is to allow us to leave behind
2750 mistakes in version numbering, and to cope with situations
2751 where the version numbering scheme changes. It is
2752 <em>not</em> intended to cope with version numbers containing
2753 strings of letters which the package management system cannot
2754 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2755 silly orderings (the author of this manual has heard of a
2756 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2757 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2758 <tt>2</tt> and so forth).
2762 <sect1 id="f-Description">
2763 <heading><tt>Description</tt></heading>
2766 In a source or binary control file, the <tt>Description</tt>
2767 field contains a description of the binary package, consisting
2768 of two parts, the synopsis or the short description, and the
2769 long description. The field's format is as follows:
2774 Description: <single line synopsis>
2775 <extended description over several lines>
2780 The lines in the extended description can have these formats:
2786 Those starting with a single space are part of a paragraph.
2787 Successive lines of this form will be word-wrapped when
2788 displayed. The leading space will usually be stripped off.
2792 Those starting with two or more spaces. These will be
2793 displayed verbatim. If the display cannot be panned
2794 horizontally, the displaying program will linewrap them "hard"
2795 (i.e., without taking account of word breaks). If it can they
2796 will be allowed to trail off to the right. None, one or two
2797 initial spaces may be deleted, but the number of spaces
2798 deleted from each line will be the same (so that you can have
2799 indenting work correctly, for example).
2803 Those containing a single space followed by a single full stop
2804 character. These are rendered as blank lines. This is the
2805 <em>only</em> way to get a blank line<footnote>
2806 Completely empty lines will not be rendered as blank lines.
2807 Instead, they will cause the parser to think you're starting
2808 a whole new record in the control file, and will therefore
2809 likely abort with an error.
2814 Those containing a space, a full stop and some more characters.
2815 These are for future expansion. Do not use them.
2821 Do not use tab characters. Their effect is not predictable.
2825 See <ref id="descriptions"> for further information on this.
2829 In a <file>.changes</file> file, the <tt>Description</tt> field
2830 contains a summary of the descriptions for the packages being
2835 The part of the field before the first newline is empty;
2836 thereafter each line has the name of a binary package and
2837 the summary description line from that binary package.
2838 Each line is indented by one space.
2843 <sect1 id="f-Distribution">
2844 <heading><tt>Distribution</tt></heading>
2847 In a <file>.changes</file> file or parsed changelog output
2848 this contains the (space-separated) name(s) of the
2849 distribution(s) where this version of the package should
2850 be installed. Valid distributions are determined by the
2851 archive maintainers.<footnote>
2852 Current distribution names are:
2853 <taglist compact="compact">
2854 <tag><em>stable</em></tag>
2856 This is the current "released" version of Debian
2857 GNU/Linux. Once the distribution is
2858 <em>stable</em> only security fixes and other
2859 major bug fixes are allowed. When changes are
2860 made to this distribution, the release number is
2861 increased (for example: 2.2r1 becomes 2.2r2 then
2865 <tag><em>unstable</em></tag>
2867 This distribution value refers to the
2868 <em>developmental</em> part of the Debian
2869 distribution tree. New packages, new upstream
2870 versions of packages and bug fixes go into the
2871 <em>unstable</em> directory tree. Download from
2872 this distribution at your own risk.
2875 <tag><em>testing</em></tag>
2877 This distribution value refers to the
2878 <em>testing</em> part of the Debian distribution
2879 tree. It receives its packages from the
2880 unstable distribution after a short time lag to
2881 ensure that there are no major issues with the
2882 unstable packages. It is less prone to breakage
2883 than unstable, but still risky. It is not
2884 possible to upload packages directly to
2888 <tag><em>frozen</em></tag>
2890 From time to time, the <em>testing</em>
2891 distribution enters a state of "code-freeze" in
2892 anticipation of release as a <em>stable</em>
2893 version. During this period of testing only
2894 fixes for existing or newly-discovered bugs will
2895 be allowed. The exact details of this stage are
2896 determined by the Release Manager.
2899 <tag><em>experimental</em></tag>
2901 The packages with this distribution value are
2902 deemed by their maintainers to be high
2903 risk. Oftentimes they represent early beta or
2904 developmental packages from various sources that
2905 the maintainers want people to try, but are not
2906 ready to be a part of the other parts of the
2907 Debian distribution tree. Download at your own
2913 You should list <em>all</em> distributions that the
2914 package should be installed into.
2918 More information is available in the Debian Developer's
2919 Reference, section "The Debian archive".
2926 <heading><tt>Date</tt></heading>
2929 This field includes the date the package was built or last edited.
2933 The value of this field is usually extracted from the
2934 <file>debian/changelog</file> file - see
2935 <ref id="dpkgchangelog">).
2939 <sect1 id="f-Format">
2940 <heading><tt>Format</tt></heading>
2943 This field specifies a format revision for the file.
2944 The most current format described in the Policy Manual
2945 is version <strong>1.5</strong>. The syntax of the
2946 format value is the same as that of a package version
2947 number except that no epoch or Debian revision is allowed
2948 - see <ref id="f-Version">.
2952 <sect1 id="f-Urgency">
2953 <heading><tt>Urgency</tt></heading>
2956 This is a description of how important it is to upgrade to
2957 this version from previous ones. It consists of a single
2958 keyword usually taking one of the values <tt>low</tt>,
2959 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2960 followed by an optional commentary (separated by a space)
2961 which is usually in parentheses. For example:
2964 Urgency: low (HIGH for users of diversions)
2970 The value of this field is usually extracted from the
2971 <file>debian/changelog</file> file - see
2972 <ref id="dpkgchangelog">.
2976 <sect1 id="f-Changes">
2977 <heading><tt>Changes</tt></heading>
2980 This field contains the human-readable changes data, describing
2981 the differences between the last version and the current one.
2985 There should be nothing in this field before the first
2986 newline; all the subsequent lines must be indented by at
2987 least one space; blank lines must be represented by a line
2988 consiting only of a space and a full stop.
2992 The value of this field is usually extracted from the
2993 <file>debian/changelog</file> file - see
2994 <ref id="dpkgchangelog">).
2998 Each version's change information should be preceded by a
2999 "title" line giving at least the version, distribution(s)
3000 and urgency, in a human-readable way.
3004 If data from several versions is being returned the entry
3005 for the most recent version should be returned first, and
3006 entries should be separated by the representation of a
3007 blank line (the "title" line may also be followed by the
3008 representation of blank line).
3012 <sect1 id="f-Binary">
3013 <heading><tt>Binary</tt></heading>
3016 This field is a list of binary packages.
3020 When it appears in the <file>.dsc</file> file it is the list
3021 of binary packages which a source package can produce. It
3022 does not necessarily produce all of these binary packages
3023 for every architecture. The source control file doesn't
3024 contain details of which architectures are appropriate for
3025 which of the binary packages.
3029 When it appears in a <file>.changes</file> file it lists the
3030 names of the binary packages actually being uploaded.
3034 The syntax is a list of binary packages separated by
3036 A space after each comma is conventional.
3037 </footnote>. Currently the packages must be separated using
3038 only spaces in the <file>.changes</file> file.
3042 <sect1 id="f-Installed-Size">
3043 <heading><tt>Installed-Size</tt></heading>
3046 This field appears in the control files of binary
3047 packages, and in the <file>Packages</file> files. It gives
3048 the total amount of disk space required to install the
3053 The disk space is represented in kilobytes as a simple
3058 <sect1 id="f-Files">
3059 <heading><tt>Files</tt></heading>
3062 This field contains a list of files with information about
3063 each one. The exact information and syntax varies with
3064 the context. In all cases the part of the field
3065 contents on the same line as the field name is empty. The
3066 remainder of the field is one line per file, each line
3067 being indented by one space and containing a number of
3068 sub-fields separated by spaces.
3072 In the <file>.dsc</file> file, each line contains the MD5
3073 checksum, size and filename of the tar file and (if applicable)
3074 diff file which make up the remainder of the source
3076 That is, the parts which are not the <tt>.dsc</tt>.
3078 The exact forms of the filenames are described
3079 in <ref id="pkg-sourcearchives">.
3083 In the <file>.changes</file> file this contains one line per
3084 file being uploaded. Each line contains the MD5 checksum,
3085 size, section and priority and the filename.
3086 The <qref id="f-Section">section</qref>
3087 and <qref id="f-Priority">priority</qref>
3088 are the values of the corresponding fields in
3089 the main source control file. If no section or priority is
3090 specified then <tt>-</tt> should be used, though section
3091 and priority values must be specified for new packages to
3092 be installed properly.
3096 The special value <tt>byhand</tt> for the section in a
3097 <tt>.changes</tt> file indicates that the file in question
3098 is not an ordinary package file and must by installed by
3099 hand by the distribution maintainers. If the section is
3100 <tt>byhand</tt> the priority should be <tt>-</tt>.
3104 If a new Debian revision of a package is being shipped and
3105 no new original source archive is being distributed the
3106 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3107 entry for the original source archive
3108 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3109 but the <file>.changes</file> file should leave it out. In
3110 this case the original source archive on the distribution
3111 site must match exactly, byte-for-byte, the original
3112 source archive which was used to generate the
3113 <file>.dsc</file> file and diff which are being uploaded.</p>
3116 <sect1 id="f-Closes">
3117 <heading><tt>Closes</tt></heading>
3120 A space-separated list of bug report numbers that the upload
3121 governed by the .changes file closes.
3128 <heading>User-defined fields</heading>
3131 Additional user-defined fields may be added to the
3132 source package control file. Such fields will be
3133 ignored, and not copied to (for example) binary or
3134 source package control files or upload control files.
3138 If you wish to add additional unsupported fields to
3139 these output files you should use the mechanism
3144 Fields in the main source control information file with
3145 names starting <tt>X</tt>, followed by one or more of
3146 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3147 be copied to the output files. Only the part of the
3148 field name after the hyphen will be used in the output
3149 file. Where the letter <tt>B</tt> is used the field
3150 will appear in binary package control files, where the
3151 letter <tt>S</tt> is used in source package control
3152 files and where <tt>C</tt> is used in upload control
3153 (<tt>.changes</tt>) files.
3157 For example, if the main source information control file
3160 XBS-Comment: I stand between the candle and the star.
3162 then the binary and source package control files will contain the
3165 Comment: I stand between the candle and the star.
3174 <chapt id="maintainerscripts">
3175 <heading>Package maintainer scripts and installation procedure</heading>
3178 <heading>Introduction to package maintainer scripts</heading>
3181 It is possible to supply scripts as part of a package which
3182 the package management system will run for you when your
3183 package is installed, upgraded or removed.
3187 These scripts are the files <prgn>preinst</prgn>,
3188 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3189 control area of the package. They must be proper executable
3190 files; if they are scripts (which is recommended), they must
3191 start with the usual <tt>#!</tt> convention. They should be
3192 readable and executable by anyone, and not world-writable.
3196 The package management system looks at the exit status from
3197 these scripts. It is important that they exit with a
3198 non-zero status if there is an error, so that the package
3199 management system can stop its processing. For shell
3200 scripts this means that you <em>almost always</em> need to
3201 use <tt>set -e</tt> (this is usually true when writing shell
3202 scripts, in fact). It is also important, of course, that
3203 they don't exit with a non-zero status if everything went
3208 When a package is upgraded a combination of the scripts from
3209 the old and new packages is called during the upgrade
3210 procedure. If your scripts are going to be at all
3211 complicated you need to be aware of this, and may need to
3212 check the arguments to your scripts.
3216 Broadly speaking the <prgn>preinst</prgn> is called before
3217 (a particular version of) a package is installed, and the
3218 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3219 before (a version of) a package is removed and the
3220 <prgn>postrm</prgn> afterwards.
3224 Programs called from maintainer scripts should not normally
3225 have a path prepended to them. Before installation is
3226 started, the package management system checks to see if the
3227 programs <prgn>ldconfig</prgn>,
3228 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3229 and <prgn>update-rc.d</prgn> can be found via the
3230 <tt>PATH</tt> environment variable. Those programs, and any
3231 other program that one would expect to be on the
3232 <tt>PATH</tt>, should thus be invoked without an absolute
3233 pathname. Maintainer scripts should also not reset the
3234 <tt>PATH</tt>, though they might choose to modify it by
3235 prepending or appending package-specific directories. These
3236 considerations really apply to all shell scripts.</p>
3239 <sect id="idempotency">
3240 <heading>Maintainer scripts Idempotency</heading>
3243 It is necessary for the error recovery procedures that the
3244 scripts be idempotent. This means that if it is run
3245 successfully, and then it is called again, it doesn't bomb
3246 out or cause any harm, but just ensures that everything is
3247 the way it ought to be. If the first call failed, or
3248 aborted half way through for some reason, the second call
3249 should merely do the things that were left undone the first
3250 time, if any, and exit with a success status if everything
3252 This is so that if an error occurs, the user interrupts
3253 <prgn>dpkg</prgn> or some other unforeseen circumstance
3254 happens you don't leave the user with a badly-broken
3255 package when <prgn>dpkg</prgn> attempts to repeat the
3261 <sect id="controllingterminal">
3262 <heading>Controlling terminal for maintainer scripts</heading>
3265 The maintainer scripts are guaranteed to run with a
3266 controlling terminal and can interact with the user.
3267 If they need to prompt for passwords, do full-screen
3268 interaction or something similar you should do these
3269 things to and from <file>/dev/tty</file>, since
3270 <prgn>dpkg</prgn> will at some point redirect scripts'
3271 standard input and output so that it can log the
3272 installation process. Likewise, because these scripts
3273 may be executed with standard output redirected into a
3274 pipe for logging purposes, Perl scripts should set
3275 unbuffered output by setting <tt>$|=1</tt> so that the
3276 output is printed immediately rather than being
3281 Each script should return a zero exit status for
3282 success, or a nonzero one for failure.
3286 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3291 <list compact="compact">
3293 <var>new-preinst</var> <tt>install</tt>
3296 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3299 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3302 <var>old-preinst</var> <tt>abort-upgrade</tt>
3303 <var>new-version</var>
3308 <list compact="compact">
3310 <var>postinst</var> <tt>configure</tt>
3311 <var>most-recently-configured-version</var>
3314 <var>old-postinst</var> <tt>abort-upgrade</tt>
3315 <var>new-version</var>
3318 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3319 <tt>in-favour</tt> <var>package</var>
3320 <var>new-version</var>
3323 <var>deconfigured's-postinst</var>
3324 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3325 <var>failed-install-package</var> <var>version</var>
3326 <tt>removing</tt> <var>conflicting-package</var>
3332 <list compact="compact">
3334 <var>prerm</var> <tt>remove</tt>
3337 <var>old-prerm</var> <tt>upgrade</tt>
3338 <var>new-version</var>
3341 <var>new-prerm</var> <tt>failed-upgrade</tt>
3342 <var>old-version</var>
3345 <var>conflictor's-prerm</var> <tt>remove</tt>
3346 <tt>in-favour</tt> <var>package</var>
3347 <var>new-version</var>
3350 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3351 <tt>in-favour</tt> <var>package-being-installed</var>
3352 <var>version</var> <tt>removing</tt>
3353 <var>conflicting-package</var>
3359 <list compact="compact">
3361 <var>postrm</var> <tt>remove</tt>
3364 <var>postrm</var> <tt>purge</tt>
3367 <var>old-postrm</var> <tt>upgrade</tt>
3368 <var>new-version</var>
3371 <var>new-postrm</var> <tt>failed-upgrade</tt>
3372 <var>old-version</var>
3375 <var>new-postrm</var> <tt>abort-install</tt>
3378 <var>new-postrm</var> <tt>abort-install</tt>
3379 <var>old-version</var>
3382 <var>new-postrm</var> <tt>abort-upgrade</tt>
3383 <var>old-version</var>
3386 <var>disappearer's-postrm</var> <tt>disappear</tt>
3387 <var>overwriter</var>
3388 <var>overwriter-version</var>
3394 <sect id="unpackphase">
3395 <heading>Details of unpack phase of installation or upgrade</heading>
3398 The procedure on installation/upgrade/overwrite/disappear
3399 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3400 stage of <tt>dpkg --install</tt>) is as follows. In each
3401 case, if a major error occurs (unless listed below) the
3402 actions are, in general, run backwards - this means that the
3403 maintainer scripts are run with different arguments in
3404 reverse order. These are the "error unwind" calls listed
3411 If a version of the package is already installed, call
3412 <example compact="compact">
3413 <var>old-prerm</var> upgrade <var>new-version</var>
3417 If the script runs but exits with a non-zero
3418 exit status, <prgn>dpkg</prgn> will attempt:
3419 <example compact="compact">
3420 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3422 Error unwind, for both the above cases:
3423 <example compact="compact">
3424 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3431 If a "conflicting" package is being removed at the same time:
3434 If any packages depended on that conflicting
3435 package and <tt>--auto-deconfigure</tt> is
3436 specified, call, for each such package:
3437 <example compact="compact">
3438 <var>deconfigured's-prerm</var> deconfigure \
3439 in-favour <var>package-being-installed</var> <var>version</var> \
3440 removing <var>conflicting-package</var> <var>version</var>
3443 <example compact="compact">
3444 <var>deconfigured's-postinst</var> abort-deconfigure \
3445 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3446 removing <var>conflicting-package</var> <var>version</var>
3448 The deconfigured packages are marked as
3449 requiring configuration, so that if
3450 <tt>--install</tt> is used they will be
3451 configured again if possible.
3454 To prepare for removal of the conflicting package, call:
3455 <example compact="compact">
3456 <var>conflictor's-prerm</var> remove \
3457 in-favour <var>package</var> <var>new-version</var>
3460 <example compact="compact">
3461 <var>conflictor's-postinst</var> abort-remove \
3462 in-favour <var>package</var> <var>new-version</var>
3471 If the package is being upgraded, call:
3472 <example compact="compact">
3473 <var>new-preinst</var> upgrade <var>old-version</var>
3477 Otherwise, if the package had some configuration
3478 files from a previous version installed (i.e., it
3479 is in the "configuration files only" state):
3480 <example compact="compact">
3481 <var>new-preinst</var> install <var>old-version</var>
3485 Otherwise (i.e., the package was completely purged):
3486 <example compact="compact">
3487 <var>new-preinst</var> install
3489 Error unwind actions, respectively:
3490 <example compact="compact">
3491 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3492 <var>new-postrm</var> abort-install <var>old-version</var>
3493 <var>new-postrm</var> abort-install
3501 The new package's files are unpacked, overwriting any
3502 that may be on the system already, for example any
3503 from the old version of the same package or from
3504 another package. Backups of the old files are kept
3505 temporarily, and if anything goes wrong the package
3506 management system will attempt to put them back as
3507 part of the error unwind.
3511 It is an error for a package to contain files which
3512 are on the system in another package, unless
3513 <tt>Replaces</tt> is used (see <ref id="replaces">).
3515 The following paragraph is not currently the case:
3516 Currently the <tt>- - force-overwrite</tt> flag is
3517 enabled, downgrading it to a warning, but this may not
3523 It is a more serious error for a package to contain a
3524 plain file or other kind of non-directory where another
3525 package has a directory (again, unless
3526 <tt>Replaces</tt> is used). This error can be
3527 overridden if desired using
3528 <tt>--force-overwrite-dir</tt>, but this is not
3533 Packages which overwrite each other's files produce
3534 behavior which, though deterministic, is hard for the
3535 system administrator to understand. It can easily
3536 lead to "missing" programs if, for example, a package
3537 is installed which overwrites a file from another
3538 package, and is then removed again.<footnote>
3539 Part of the problem is due to what is arguably a
3540 bug in <prgn>dpkg</prgn>.
3545 A directory will never be replaced by a symbolic link
3546 to a directory or vice versa; instead, the existing
3547 state (symlink or not) will be left alone and
3548 <prgn>dpkg</prgn> will follow the symlink if there is
3557 If the package is being upgraded, call
3558 <example compact="compact">
3559 <var>old-postrm</var> upgrade <var>new-version</var>
3563 If this fails, <prgn>dpkg</prgn> will attempt:
3564 <example compact="compact">
3565 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3567 Error unwind, for both cases:
3568 <example compact="compact">
3569 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3576 This is the point of no return - if
3577 <prgn>dpkg</prgn> gets this far, it won't back off
3578 past this point if an error occurs. This will
3579 leave the package in a fairly bad state, which
3580 will require a successful re-installation to clear
3581 up, but it's when <prgn>dpkg</prgn> starts doing
3582 things that are irreversible.
3587 Any files which were in the old version of the package
3588 but not in the new are removed.
3592 The new file list replaces the old.
3596 The new maintainer scripts replace the old.
3600 Any packages all of whose files have been overwritten
3601 during the installation, and which aren't required for
3602 dependencies, are considered to have been removed.
3603 For each such package
3606 <prgn>dpkg</prgn> calls:
3607 <example compact="compact">
3608 <var>disappearer's-postrm</var> disappear \
3609 <var>overwriter</var> <var>overwriter-version</var>
3613 The package's maintainer scripts are removed.
3616 It is noted in the status database as being in a
3617 sane state, namely not installed (any conffiles
3618 it may have are ignored, rather than being
3619 removed by <prgn>dpkg</prgn>). Note that
3620 disappearing packages do not have their prerm
3621 called, because <prgn>dpkg</prgn> doesn't know
3622 in advance that the package is going to
3629 Any files in the package we're unpacking that are also
3630 listed in the file lists of other packages are removed
3631 from those lists. (This will lobotomize the file list
3632 of the "conflicting" package if there is one.)
3636 The backup files made during installation, above, are
3642 The new package's status is now sane, and recorded as
3647 Here is another point of no return - if the
3648 conflicting package's removal fails we do not unwind
3649 the rest of the installation; the conflicting package
3650 is left in a half-removed limbo.
3655 If there was a conflicting package we go and do the
3656 removal actions (described below), starting with the
3657 removal of the conflicting package's files (any that
3658 are also in the package being installed have already
3659 been removed from the conflicting package's file list,
3660 and so do not get removed now).
3666 <sect id="configdetails"><heading>Details of configuration</heading>
3669 When we configure a package (this happens with <tt>dpkg
3670 --install</tt> and <tt>dpkg --configure</tt>), we first
3671 update any <tt>conffile</tt>s and then call:
3672 <example compact="compact">
3673 <var>postinst</var> configure <var>most-recently-configured-version</var>
3678 No attempt is made to unwind after errors during
3683 If there is no most recently configured version
3684 <prgn>dpkg</prgn> will pass a null argument.
3687 Historical note: Truly ancient (pre-1997) versions of
3688 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3689 (including the angle brackets) in this case. Even older
3690 ones did not pass a second argument at all, under any
3691 circumstance. Note that upgrades using such an old dpkg
3692 version are unlikely to work for other reasons, even if
3693 this old argument behavior is handled by your postinst script.
3699 <sect id="removedetails"><heading>Details of removal and/or
3700 configuration purging</heading>
3705 <example compact="compact">
3706 <var>prerm</var> remove
3710 The package's files are removed (except <tt>conffile</tt>s).
3713 <example compact="compact">
3714 <var>postrm</var> remove
3719 All the maintainer scripts except the <prgn>postrm</prgn>
3724 If we aren't purging the package we stop here. Note
3725 that packages which have no <prgn>postrm</prgn> and no
3726 <tt>conffile</tt>s are automatically purged when
3727 removed, as there is no difference except for the
3728 <prgn>dpkg</prgn> status.
3732 The <tt>conffile</tt>s and any backup files
3733 (<tt>~</tt>-files, <tt>#*#</tt> files,
3734 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3738 <example compact="compact">
3739 <var>postrm</var> purge
3743 The package's file list is removed.
3747 If there are problems during this process, we call
3748 <example compact="compact">postinst
3749 abort-remove</example>. No other attempt is made to unwind
3750 after errors during removal.
3756 <chapt id="relationships">
3757 <heading>Declaring relationships between packages</heading>
3759 <sect id="depsyntax">
3760 <heading>Syntax of relationship fields</heading>
3763 These fields all have a uniform syntax. They are a list of
3764 package names separated by commas.
3768 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3769 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3770 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3771 control file fields of the package, which declare
3772 dependencies on other packages, the package names listed may
3773 also include lists of alternative package names, separated
3774 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3775 if any one of the alternative packages is installed, that
3776 part of the dependency is considered to be satisfied.
3780 All of the fields except for <tt>Provides</tt> may restrict
3781 their applicability to particular versions of each named
3782 package. This is done in parentheses after each individual
3783 package name; the parentheses should contain a relation from
3784 the list below followed by a version number, in the format
3785 described in <ref id="f-Version">.
3789 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3790 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3791 strictly earlier, earlier or equal, exactly equal, later or
3792 equal and strictly later, respectively. The deprecated
3793 forms <tt><</tt> and <tt>></tt> were used to mean
3794 earlier/later or equal, rather than strictly earlier/later,
3795 so they should not appear in new packages (though
3796 <prgn>dpkg</prgn> still supports them).
3800 Whitespace may appear at any point in the version
3801 specification subject to the rules in <ref
3802 id="controlsyntax">, and must appear where it's necessary to
3803 disambiguate; it is not otherwise significant. For
3804 consistency and in case of future changes to
3805 <prgn>dpkg</prgn> it is recommended that a single space be
3806 used after a version relationship and before a version
3807 number; it is also conventional to put a single space after
3808 each comma, on either side of each vertical bar, and before
3809 each open parenthesis.
3813 For example, a list of dependencies might appear as:
3814 <example compact="compact">
3817 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3822 All fields that specify build-time relationships
3823 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3824 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3825 may be restricted to a certain set of architectures. This
3826 is indicated in brackets after each individual package name and
3827 the optional version specification. The brackets enclose a
3828 list of Debian architecture names separated by whitespace.
3829 Exclamation marks may be prepended to each of the names.
3830 (It is not permitted for some names to be prepended with
3831 exclamation marks and others not.) If the current Debian
3832 host architecture is not in this list and there are no
3833 exclamation marks in the list, or it is in the list with a
3834 prepended exclamation mark, the package name and the
3835 associated version specification are ignored completely for
3836 the purposes of defining the relationships.
3841 <example compact="compact">
3843 Build-Depends-Indep: texinfo
3844 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3845 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3850 Note that the binary package relationship fields such as
3851 <tt>Depends</tt> appear in one of the binary package
3852 sections of the control file, whereas the build-time
3853 relationships such as <tt>Build-Depends</tt> appear in the
3854 source package section of the control file (which is the
3859 <sect id="binarydeps">
3860 <heading>Binary Dependencies - <tt>Depends</tt>,
3861 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3862 <tt>Pre-Depends</tt>
3866 Packages can declare in their control file that they have
3867 certain relationships to other packages - for example, that
3868 they may not be installed at the same time as certain other
3869 packages, and/or that they depend on the presence of others.
3873 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3874 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3875 <tt>Conflicts</tt> control file fields.
3879 These six fields are used to declare a dependency
3880 relationship by one package on another. Except for
3881 <tt>Enhances</tt>, they appear in the depending (binary)
3882 package's control file. (<tt>Enhances</tt> appears in the
3883 recommending package's control file.)
3887 A <tt>Depends</tt> field takes effect <em>only</em> when a
3888 package is to be configured. It does not prevent a package
3889 being on the system in an unconfigured state while its
3890 dependencies are unsatisfied, and it is possible to replace
3891 a package whose dependencies are satisfied and which is
3892 properly installed with a different version whose
3893 dependencies are not and cannot be satisfied; when this is
3894 done the depending package will be left unconfigured (since
3895 attempts to configure it will give errors) and will not
3896 function properly. If it is necessary, a
3897 <tt>Pre-Depends</tt> field can be used, which has a partial
3898 effect even when a package is being unpacked, as explained
3899 in detail below. (The other three dependency fields,
3900 <tt>Recommends</tt>, <tt>Suggests</tt> and
3901 <tt>Enhances</tt>, are only used by the various front-ends
3902 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3906 For this reason packages in an installation run are usually
3907 all unpacked first and all configured later; this gives
3908 later versions of packages with dependencies on later
3909 versions of other packages the opportunity to have their
3910 dependencies satisfied.
3914 The <tt>Depends</tt> field thus allows package maintainers
3915 to impose an order in which packages should be configured.
3919 The meaning of the five dependency fields is as follows:
3921 <tag><tt>Depends</tt></tag>
3924 This declares an absolute dependency. A package will
3925 not be configured unless all of the packages listed in
3926 its <tt>Depends</tt> field have been correctly
3931 The <tt>Depends</tt> field should be used if the
3932 depended-on package is required for the depending
3933 package to provide a significant amount of
3938 The <tt>Depends</tt> field should also be used if the
3939 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3940 <prgn>postrm</prgn> scripts require the package to be
3941 present in order to run. Note, however, that the
3942 <prgn>postrm</prgn> cannot rely on any non-essential
3943 packages to be present during the <tt>purge</tt>
3947 <tag><tt>Recommends</tt></tag>
3950 This declares a strong, but not absolute, dependency.
3954 The <tt>Recommends</tt> field should list packages
3955 that would be found together with this one in all but
3956 unusual installations.
3960 <tag><tt>Suggests</tt></tag>
3962 This is used to declare that one package may be more
3963 useful with one or more others. Using this field
3964 tells the packaging system and the user that the
3965 listed packages are related to this one and can
3966 perhaps enhance its usefulness, but that installing
3967 this one without them is perfectly reasonable.
3970 <tag><tt>Enhances</tt></tag>
3972 This field is similar to Suggests but works in the
3973 opposite direction. It is used to declare that a
3974 package can enhance the functionality of another
3978 <tag><tt>Pre-Depends</tt></tag>
3981 This field is like <tt>Depends</tt>, except that it
3982 also forces <prgn>dpkg</prgn> to complete installation
3983 of the packages named before even starting the
3984 installation of the package which declares the
3985 pre-dependency, as follows:
3989 When a package declaring a pre-dependency is about to
3990 be <em>unpacked</em> the pre-dependency can be
3991 satisfied if the depended-on package is either fully
3992 configured, <em>or even if</em> the depended-on
3993 package(s) are only unpacked or half-configured,
3994 provided that they have been configured correctly at
3995 some point in the past (and not removed or partially
3996 removed since). In this case, both the
3997 previously-configured and currently unpacked or
3998 half-configured versions must satisfy any version
3999 clause in the <tt>Pre-Depends</tt> field.
4003 When the package declaring a pre-dependency is about
4004 to be <em>configured</em>, the pre-dependency will be
4005 treated as a normal <tt>Depends</tt>, that is, it will
4006 be considered satisfied only if the depended-on
4007 package has been correctly configured.
4011 <tt>Pre-Depends</tt> should be used sparingly,
4012 preferably only by packages whose premature upgrade or
4013 installation would hamper the ability of the system to
4014 continue with any upgrade that might be in progress.
4018 <tt>Pre-Depends</tt> are also required if the
4019 <prgn>preinst</prgn> script depends on the named
4020 package. It is best to avoid this situation if
4028 When selecting which level of dependency to use you should
4029 consider how important the depended-on package is to the
4030 functionality of the one declaring the dependency. Some
4031 packages are composed of components of varying degrees of
4032 importance. Such a package should list using
4033 <tt>Depends</tt> the package(s) which are required by the
4034 more important components. The other components'
4035 requirements may be mentioned as Suggestions or
4036 Recommendations, as appropriate to the components' relative
4041 <sect id="conflicts">
4042 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4045 When one binary package declares a conflict with another
4046 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4047 refuse to allow them to be installed on the system at the
4052 If one package is to be installed, the other must be removed
4053 first - if the package being installed is marked as
4054 replacing (see <ref id="replaces">) the one on the system,
4055 or the one on the system is marked as deselected, or both
4056 packages are marked <tt>Essential</tt>, then
4057 <prgn>dpkg</prgn> will automatically remove the package
4058 which is causing the conflict, otherwise it will halt the
4059 installation of the new package with an error. This
4060 mechanism is specifically designed to produce an error when
4061 the installed package is <tt>Essential</tt>, but the new
4066 A package will not cause a conflict merely because its
4067 configuration files are still installed; it must be at least
4072 A special exception is made for packages which declare a
4073 conflict with their own package name, or with a virtual
4074 package which they provide (see below): this does not
4075 prevent their installation, and allows a package to conflict
4076 with others providing a replacement for it. You use this
4077 feature when you want the package in question to be the only
4078 package providing some feature.
4082 A <tt>Conflicts</tt> entry should almost never have an
4083 "earlier than" version clause. This would prevent
4084 <prgn>dpkg</prgn> from upgrading or installing the package
4085 which declared such a conflict until the upgrade or removal
4086 of the conflicted-with package had been completed.
4090 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4094 As well as the names of actual ("concrete") packages, the
4095 package relationship fields <tt>Depends</tt>,
4096 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4097 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4098 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4099 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4100 may mention "virtual packages".
4104 A <em>virtual package</em> is one which appears in the
4105 <tt>Provides</tt> control file field of another package.
4106 The effect is as if the package(s) which provide a
4107 particular virtual package name had been listed by name
4108 everywhere the virtual package name appears. (See also <ref
4113 If there are both concrete and virtual packages of the same
4114 name, then the dependency may be satisfied (or the conflict
4115 caused) by either the concrete package with the name in
4116 question or any other concrete package which provides the
4117 virtual package with the name in question. This is so that,
4118 for example, supposing we have
4119 <example compact="compact">
4123 and someone else releases an enhanced version of the
4124 <tt>bar</tt> package (for example, a non-US variant), they
4126 <example compact="compact">
4130 and the <tt>bar-plus</tt> package will now also satisfy the
4131 dependency for the <tt>foo</tt> package.
4135 If a dependency or a conflict has a version number attached
4136 then only real packages will be considered to see whether
4137 the relationship is satisfied (or the prohibition violated,
4138 for a conflict) - it is assumed that a real package which
4139 provides the virtual package is not of the "right" version.
4140 So, a <tt>Provides</tt> field may not contain version
4141 numbers, and the version number of the concrete package
4142 which provides a particular virtual package will not be
4143 looked at when considering a dependency on or conflict with
4144 the virtual package name.
4148 It is likely that the ability will be added in a future
4149 release of <prgn>dpkg</prgn> to specify a version number for
4150 each virtual package it provides. This feature is not yet
4151 present, however, and is expected to be used only
4156 If you want to specify which of a set of real packages
4157 should be the default to satisfy a particular dependency on
4158 a virtual package, you should list the real package as an
4159 alternative before the virtual one.
4164 <sect id="replaces"><heading>Overwriting files and replacing
4165 packages - <tt>Replaces</tt></heading>
4168 Packages can declare in their control file that they should
4169 overwrite files in certain other packages, or completely
4170 replace other packages. The <tt>Replaces</tt> control file
4171 field has these two distinct purposes.
4174 <sect1><heading>Overwriting files in other packages</heading>
4177 Firstly, as mentioned before, it is usually an error for a
4178 package to contain files which are on the system in
4183 However, if the overwriting package declares that it
4184 <tt>Replaces</tt> the one containing the file being
4185 overwritten, then <prgn>dpkg</prgn> will replace the file
4186 from the old package with that from the new. The file
4187 will no longer be listed as "owned" by the old package.
4191 If a package is completely replaced in this way, so that
4192 <prgn>dpkg</prgn> does not know of any files it still
4193 contains, it is considered to have "disappeared". It will
4194 be marked as not wanted on the system (selected for
4195 removal) and not installed. Any <tt>conffile</tt>s
4196 details noted for the package will be ignored, as they
4197 will have been taken over by the overwriting package. The
4198 package's <prgn>postrm</prgn> script will be run with a
4199 special argument to allow the package to do any final
4200 cleanup required. See <ref id="mscriptsinstact">.
4203 Replaces is a one way relationship -- you have to
4204 install the replacing package after the replaced
4211 For this usage of <tt>Replaces</tt>, virtual packages (see
4212 <ref id="virtual">) are not considered when looking at a
4213 <tt>Replaces</tt> field - the packages declared as being
4214 replaced must be mentioned by their real names.
4218 Furthermore, this usage of <tt>Replaces</tt> only takes
4219 effect when both packages are at least partially on the
4220 system at once, so that it can only happen if they do not
4221 conflict or if the conflict has been overridden.
4226 <sect1><heading>Replacing whole packages, forcing their
4230 Secondly, <tt>Replaces</tt> allows the packaging system to
4231 resolve which package should be removed when there is a
4232 conflict - see <ref id="conflicts">. This usage only
4233 takes effect when the two packages <em>do</em> conflict,
4234 so that the two usages of this field do not interfere with
4239 In this situation, the package declared as being replaced
4240 can be a virtual package, so for example, all mail
4241 transport agents (MTAs) would have the following fields in
4242 their control files:
4243 <example compact="compact">
4244 Provides: mail-transport-agent
4245 Conflicts: mail-transport-agent
4246 Replaces: mail-transport-agent
4248 ensuring that only one MTA can be installed at any one
4253 <sect id="sourcebinarydeps">
4254 <heading>Relationships between source and binary packages -
4255 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4256 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4260 Source packages that require certain binary packages to be
4261 installed or absent at the time of building the package
4262 can declare relationships to those binary packages.
4266 This is done using the <tt>Build-Depends</tt>,
4267 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4268 <tt>Build-Conflicts-Indep</tt> control file fields.
4272 Build-dependencies on "build-essential" binary packages can be
4273 omitted. Please see <ref id="pkg-relations"> for more information.
4277 The dependencies and conflicts they define must be satisfied
4278 (as defined earlier for binary packages) in order to invoke
4279 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4281 If you make "build-arch" or "binary-arch", you need
4282 Build-Depends. If you make "build-indep" or
4283 "binary-indep", you need Build-Depends and
4284 Build-Depends-Indep. If you make "build" or "binary",
4288 There is no Build-Depends-Arch; the autobuilders will
4289 only need the Build-Depends if they know how to build
4290 only build-arch and binary-arch. Anyone building the
4291 build-indep/binary-indep targets is basically assumed to
4292 be building the whole package and so installs all build
4296 The purpose of the original split, I recall, was so that
4297 the autobuilders wouldn't need to install extra packages
4298 needed only for the binary-indep targets. But without a
4299 build-arch/build-indep split, this didn't work, since
4300 most of the work is done in the build target, not in the
4306 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4308 The <tt>Build-Depends</tt> and
4309 <tt>Build-Conflicts</tt> fields must be satisfied when
4310 any of the following targets is invoked:
4311 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4312 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4313 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4315 <tag><tt>Build-Depends-Indep</tt>,
4316 <tt>Build-Conflicts-Indep</tt></tag>
4318 The <tt>Build-Depends-Indep</tt> and
4319 <tt>Build-Conflicts-Indep</tt> fields must be
4320 satisfied when any of the following targets is
4321 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4322 <tt>binary</tt> and <tt>binary-indep</tt>.
4332 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4335 Packages containing shared libraries must be constructed with
4336 a little care to make sure that the shared library is always
4337 available. This is especially important for packages whose
4338 shared libraries are vitally important, such as the C library
4339 (currently <tt>libc6</tt>).
4343 Packages involving shared libraries should be split up into
4344 several binary packages. This section mostly deals with how
4345 this separation is to be accomplished; rules for files within
4346 the shared library packages are in <ref id="libraries"> instead.
4349 <sect id="sharedlibs-runtime">
4350 <heading>Run-time shared libraries</heading>
4353 The run-time shared library needs to be placed in a package called
4354 <package><var>libraryname</var><var>soversion</var></package>, where
4355 <file><var>soversion</var></file> is the version number in the
4356 soname of the shared library<footnote>
4357 The soname is the shared object name: it's the thing
4358 that has to match exactly between building an executable
4359 and running it for the dynamic linker to be able run the
4360 program. For example, if the soname of the library is
4361 <file>libfoo.so.6</file>, the library package would be
4362 called <file>libfoo6</file>.
4364 Alternatively, if it would be confusing to directly append
4365 <var>soversion</var> to <var>libraryname</var> (e.g. because
4366 <var>libraryname</var> itself ends in a number), you may use
4367 <package><var>libraryname</var>-<var>soversion</var></package> and
4368 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4373 If you have several shared libraries built from the same
4374 source tree you may lump them all together into a single
4375 shared library package, provided that you change all of
4376 their sonames at once (so that you don't get filename
4377 clashes if you try to install different versions of the
4378 combined shared libraries package).
4382 The package should install the shared libraries under
4383 their normal names. For example, the <package>libgdbm3</package>
4384 package should install <file>libgdbm.so.3.0.0</file> as
4385 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4386 renamed or re-linked by any <prgn>prerm</prgn> or
4387 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4388 of renaming things safely without affecting running programs,
4389 and attempts to interfere with this are likely to lead to
4394 Shared libraries should not be installed executable, since
4395 the dynamic linker does not require this and trying to
4396 execute a shared library usually results in a core dump.
4400 The run-time library package should include the symbolic link that
4401 <prgn>ldconfig</prgn> would create for the shared libraries.
4402 For example, the <package>libgdbm3</package> package should include
4403 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4404 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4405 linker (for example <prgn>ld.so</prgn> or
4406 <prgn>ld-linux.so.*</prgn>) can find the library between the
4407 time that <prgn>dpkg</prgn> installs it and the time that
4408 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4410 The package management system requires the library to be
4411 placed before the symbolic link pointing to it in the
4412 <file>.deb</file> file. This is so that when
4413 <prgn>dpkg</prgn> comes to install the symlink
4414 (overwriting the previous symlink pointing at an older
4415 version of the library), the new shared library is already
4416 in place. In the past, this was achieved by creating the
4417 library in the temporary packaging directory before
4418 creating the symlink. Unfortunately, this was not always
4419 effective, since the building of the tar file in the
4420 <file>.deb</file> depended on the behavior of the underlying
4421 file system. Some file systems (such as reiserfs) reorder
4422 the files so that the order of creation is forgotten.
4423 Since version 1.7.0, <prgn>dpkg</prgn>
4424 reorders the files itself as necessary when building a
4425 package. Thus it is no longer important to concern
4426 oneself with the order of file creation.
4430 <sect1 id="ldconfig">
4431 <heading><tt>ldconfig</tt></heading>
4434 Any package installing shared libraries in one of the default
4435 library directories of the dynamic linker (which are currently
4436 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4437 listed in <file>/etc/ld.so.conf</file><footnote>
4439 <list compact="compact">
4440 <item>/usr/X11R6/lib/Xaw3d</item>
4441 <item>/usr/local/lib</item>
4442 <item>/usr/lib/libc5-compat</item>
4443 <item>/lib/libc5-compat</item>
4444 <item>/usr/X11R6/lib</item>
4447 must use <prgn>ldconfig</prgn> to update the shared library
4452 The package must call <prgn>ldconfig</prgn> in the
4453 <prgn>postinst</prgn> script if the first argument is
4454 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4455 optionally invoke <prgn>ldconfig</prgn> at other times. The
4456 package should call <prgn>ldconfig</prgn> in the
4457 <prgn>postrm</prgn> script if the first argument is
4458 <tt>remove</tt>. The maintainer scripts must not invoke
4459 <prgn>ldconfig</prgn> under any circumstances other than those
4460 described in this paragraph.<footnote>
4462 During install or upgrade, the preinst is called before
4463 the new files are installed, so calling "ldconfig" is
4464 pointless. The preinst of an existing package can also be
4465 called if an upgrade fails. However, this happens during
4466 the critical time when a shared libs may exist on-disk
4467 under a temporary name. Thus, it is dangerous and
4468 forbidden by current policy to call "ldconfig" at this
4473 When a package is installed or upgraded, "postinst
4474 configure" runs after the new files are safely on-disk.
4475 Since it is perfectly safe to invoke ldconfig
4476 unconditionally in a postinst, it is OK for a package to
4477 simply put ldconfig in its postinst without checking the
4478 argument. The postinst can also be called to recover from
4479 a failed upgrade. This happens before any new files are
4480 unpacked, so there is no reason to call "ldconfig" at this
4485 For a package that is being removed, prerm is
4486 called with all the files intact, so calling ldconfig is
4487 useless. The other calls to "prerm" happen in the case of
4488 upgrade at a time when all the files of the old package
4489 are on-disk, so again calling "ldconfig" is pointless.
4493 postrm, on the other hand, is called with the "remove"
4494 argument just after the files are removed, so this is the
4495 proper time to call "ldconfig" to notify the system of the
4496 fact shared libraries from the package are removed.
4497 The postrm can be called at several other times. At the
4498 time of "postrm purge", "postrm abort-install", or "postrm
4499 abort-upgrade", calling "ldconfig" is useless because the
4500 shared lib files are not on-disk. However, when "postrm"
4501 is invoked with arguments "upgrade", "failed-upgrade", or
4502 "disappear", a shared lib may exist on-disk under a
4511 <sect id="sharedlibs-runtime-progs">
4512 <heading>Run-time support programs</heading>
4515 If your package has some run-time support programs which use
4516 the shared library you must not put them in the shared
4517 library package. If you do that then you won't be able to
4518 install several versions of the shared library without
4519 getting filename clashes.
4523 Instead, either create another package for the runtime binaries
4524 (this package might typically be named
4525 <package><var>libraryname</var>-runtime</package>; note the absence
4526 of the <var>soversion</var> in the package name), or if the
4527 development package is small, include them in there.
4531 <sect id="sharedlibs-static">
4532 <heading>Static libraries</heading>
4535 The static library (<file><var>libraryname.a</var></file>)
4536 is usually provided in addition to the shared version.
4537 It is placed into the development package (see below).
4541 In some cases, it is acceptable for a library to be
4542 available in static form only; these cases include:
4544 <item>libraries for languages whose shared library support
4545 is immature or unstable</item>
4546 <item>libraries whose interfaces are in flux or under
4547 development (commonly the case when the library's
4548 major version number is zero, or where the ABI breaks
4549 across patchlevels)</item>
4550 <item>libraries which are explicitly intended to be
4551 available only in static form by their upstream
4556 <sect id="sharedlibs-dev">
4557 <heading>Development files</heading>
4560 The development files associated to a shared library need to be
4561 placed in a package called
4562 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4563 or if you prefer only to support one development version at a
4564 time, <package><var>libraryname</var>-dev</package>.
4568 In case several development versions of a library exist, you may
4569 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4570 <ref id="conflicts">) to ensure that the user only installs one
4571 development version at a time (as different development versions are
4572 likely to have the same header files in them, which would cause a
4573 filename clash if both were installed).
4577 The development package should contain a symlink for the associated
4578 shared library without a version number. For example, the
4579 <package>libgdbm-dev</package> package should include a symlink
4580 from <file>/usr/lib/libgdbm.so</file> to
4581 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4582 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4583 <file>libgdbm.so</file> when compiling dynamically.
4587 <sect id="sharedlibs-intradeps">
4588 <heading>Dependencies between the packages of the same library</heading>
4591 Typically the development version should have an exact
4592 version dependency on the runtime library, to make sure that
4593 compilation and linking happens correctly. The
4594 <tt>${Source-Version}</tt> substitution variable can be
4595 useful for this purpose.
4599 <sect id="sharedlibs-shlibdeps">
4600 <heading>Dependencies between the library and other packages -
4601 the <tt>shlibs</tt> system</heading>
4604 If a package contains a binary or library which links to a
4605 shared library, we must ensure that when the package is
4606 installed on the system, all of the libraries needed are
4607 also installed. This requirement led to the creation of the
4608 <tt>shlibs</tt> system, which is very simple in its design:
4609 any package which <em>provides</em> a shared library also
4610 provides information on the package dependencies required to
4611 ensure the presence of this library, and any package which
4612 <em>uses</em> a shared library uses this information to
4613 determine the dependencies it requires. The files which
4614 contain the mapping from shared libraries to the necessary
4615 dependency information are called <file>shlibs</file> files.
4619 Thus, when a package is built which contains any shared
4620 libraries, it must provide a <file>shlibs</file> file for other
4621 packages to use, and when a package is built which contains
4622 any shared libraries or compiled binaries, it must run
4623 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4624 on these to determine the libraries used and hence the
4625 dependencies needed by this package.<footnote>
4627 In the past, the shared libraries linked to were
4628 determined by calling <prgn>ldd</prgn>, but now
4629 <prgn>objdump</prgn> is used to do this. The only
4630 change this makes to package building is that
4631 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4632 libraries, whereas in the past this was unnecessary.
4633 The rest of this footnote explains the advantage that
4638 We say that a binary <tt>foo</tt> <em>directly</em> uses
4639 a library <tt>libbar</tt> if it is explicitly linked
4640 with that library (that is, it uses the flag
4641 <tt>-lbar</tt> during the linking stage). Other
4642 libraries that are needed by <tt>libbar</tt> are linked
4643 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4644 linker will load them automatically when it loads
4645 <tt>libbar</tt>. A package should depend on
4646 the libraries it directly uses, and the dependencies for
4647 those libraries should automatically pull in the other
4652 Unfortunately, the <prgn>ldd</prgn> program shows both
4653 the directly and indirectly used libraries, meaning that
4654 the dependencies determined included both direct and
4655 indirect dependencies. The use of <prgn>objdump</prgn>
4656 avoids this problem by determining only the directly
4661 A good example of where this helps is the following. We
4662 could update <tt>libimlib</tt> with a new version that
4663 supports a new graphics format called dgf (but retaining
4664 the same major version number). If we used the old
4665 <prgn>ldd</prgn> method, every package that uses
4666 <tt>libimlib</tt> would need to be recompiled so it
4667 would also depend on <tt>libdgf</tt> or it wouldn't run
4668 due to missing symbols. However with the new system,
4669 packages using <tt>libimlib</tt> can rely on
4670 <tt>libimlib</tt> itself having the dependency on
4671 <tt>libdgf</tt> and so they would not need rebuilding.
4677 In the following sections, we will first describe where the
4678 various <tt>shlibs</tt> files are to be found, then how to
4679 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4680 file format and how to create them if your package contains a
4685 <heading>The <tt>shlibs</tt> files present on the system</heading>
4688 There are several places where <tt>shlibs</tt> files are
4689 found. The following list gives them in the order in which
4691 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4692 (The first one which gives the required information is used.)
4698 <p><file>debian/shlibs.local</file></p>
4701 This lists overrides for this package. Its use is
4702 described below (see <ref id="shlibslocal">).
4707 <p><file>/etc/dpkg/shlibs.override</file></p>
4710 This lists global overrides. This list is normally
4711 empty. It is maintained by the local system
4717 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4720 When packages are being built, any
4721 <file>debian/shlibs</file> files are copied into the
4722 control file area of the temporary build directory and
4723 given the name <file>shlibs</file>. These files give
4724 details of any shared libraries included in the
4726 An example may help here. Let us say that the
4727 source package <tt>foo</tt> generates two binary
4728 packages, <tt>libfoo2</tt> and
4729 <tt>foo-runtime</tt>. When building the binary
4730 packages, the two packages are created in the
4731 directories <file>debian/libfoo2</file> and
4732 <file>debian/foo-runtime</file> respectively.
4733 (<file>debian/tmp</file> could be used instead of one
4734 of these.) Since <tt>libfoo2</tt> provides the
4735 <tt>libfoo</tt> shared library, it will require a
4736 <tt>shlibs</tt> file, which will be installed in
4737 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4739 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4740 when <prgn>dpkg-shlibdeps</prgn> is run on the
4742 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4744 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4745 determine whether <tt>foo-prog</tt>'s library
4746 dependencies are satisfied by any of the libraries
4747 provided by <tt>libfoo2</tt>. For this reason,
4748 <prgn>dpkg-shlibdeps</prgn> must only be run once
4749 all of the individual binary packages'
4750 <tt>shlibs</tt> files have been installed into the
4757 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4760 These are the <file>shlibs</file> files corresponding to
4761 all of the packages installed on the system, and are
4762 maintained by the relevant package maintainers.
4767 <p><file>/etc/dpkg/shlibs.default</file></p>
4770 This file lists any shared libraries whose packages
4771 have failed to provide correct <file>shlibs</file> files.
4772 It was used when the <file>shlibs</file> setup was first
4773 introduced, but it is now normally empty. It is
4774 maintained by the <tt>dpkg</tt> maintainer.
4782 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4783 <file>shlibs</file> files</heading>
4787 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4788 into your <file>debian/rules</file> file. If your package
4789 contains only compiled binaries and libraries (but no scripts),
4790 you can use a command such as:
4791 <example compact="compact">
4792 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4793 debian/tmp/usr/lib/*
4795 Otherwise, you will need to explicitly list the compiled
4796 binaries and libraries.<footnote>
4797 If you are using <tt>debhelper</tt>, the
4798 <prgn>dh_shlibdeps</prgn> program will do this work for
4799 you. It will also correctly handle multi-binary
4805 This command puts the dependency information into the
4806 <file>debian/substvars</file> file, which is then used by
4807 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4808 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4809 field in the control file for this to work.
4813 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4814 done. If it does complain you might need to create your own
4815 <file>debian/shlibs.local</file> file, as explained below (see
4816 <ref id="shlibslocal">).
4820 If you have multiple binary packages, you will need to call
4821 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4822 compiled libraries or binaries. In such a case, you will
4823 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4824 utilities to specify a different <file>substvars</file> file.
4828 For more details on dpkg-shlibdeps, please see
4829 <ref id="pkg-dpkg-shlibdeps"> and
4830 <manref name="dpkg-shlibdeps" section="1">.
4835 <heading>The <file>shlibs</file> File Format</heading>
4838 Each <file>shlibs</file> file has the same format. Lines
4839 beginning with <tt>#</tt> are considered to be comments and
4840 are ignored. Each line is of the form:
4841 <example compact="compact">
4842 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4847 We will explain this by reference to the example of the
4848 <tt>zlib1g</tt> package, which (at the time of writing)
4849 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4853 <var>library-name</var> is the name of the shared library,
4854 in this case <tt>libz</tt>. (This must match the name part
4855 of the soname, see below.)
4859 <var>soname-version-number</var> is the version part of the
4860 soname of the library. The soname is the thing that must
4861 exactly match for the library to be recognized by the
4862 dynamic linker, and is usually of the form
4863 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4864 example, <tt>libz.so.1</tt>.<footnote>
4865 This can be determined using the command
4866 <example compact="compact">
4867 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4870 The version part is the part which comes after
4871 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4875 <var>dependencies</var> has the same syntax as a dependency
4876 field in a binary package control file. It should give
4877 details of which packages are required to satisfy a binary
4878 built against the version of the library contained in the
4879 package. See <ref id="depsyntax"> for details.
4883 In our example, if the first version of the <tt>zlib1g</tt>
4884 package which contained a minor number of at least
4885 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4886 <tt>shlibs</tt> entry for this library could say:
4887 <example compact="compact">
4888 libz 1 zlib1g (>= 1:1.1.3)
4890 The version-specific dependency is to avoid warnings from
4891 the dynamic linker about using older shared libraries with
4897 <heading>Providing a <file>shlibs</file> file</heading>
4900 If your package provides a shared library, you should create
4901 a <file>shlibs</file> file following the format described above.
4902 It is usual to call this file <file>debian/shlibs</file> (but if
4903 you have multiple binary packages, you might want to call it
4904 <file>debian/shlibs.<var>package</var></file> instead). Then
4905 let <file>debian/rules</file> install it in the control area:
4906 <example compact="compact">
4907 install -m644 debian/shlibs debian/tmp/DEBIAN
4909 or, in the case of a multi-binary package:
4910 <example compact="compact">
4911 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4913 An alternative way of doing this is to create the
4914 <file>shlibs</file> file in the control area directly from
4915 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4916 file at all,<footnote>
4917 This is what <prgn>dh_makeshlibs</prgn> in the
4918 <tt>debhelper</tt> suite does.
4920 since the <file>debian/shlibs</file> file itself is ignored by
4921 <prgn>dpkg-shlibdeps</prgn>.
4925 As <prgn>dpkg-shlibdeps</prgn> reads the
4926 <file>DEBIAN/shlibs</file> files in all of the binary packages
4927 being built from this source package, all of the
4928 <file>DEBIAN/shlibs</file> files should be installed before
4929 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4934 <sect1 id="shlibslocal">
4935 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4938 This file is intended only as a <em>temporary</em> fix if
4939 your binaries or libraries depend on a library whose package
4940 does not yet provide a correct <file>shlibs</file> file.
4944 We will assume that you are trying to package a binary
4945 <tt>foo</tt>. When you try running
4946 <prgn>dpkg-shlibdeps</prgn> you get the following error
4947 message (<tt>-O</tt> displays the dependency information on
4948 <tt>stdout</tt> instead of writing it to
4949 <tt>debian/substvars</tt>, and the lines have been wrapped
4950 for ease of reading):
4951 <example compact="compact">
4952 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4953 dpkg-shlibdeps: warning: unable to find dependency
4954 information for shared library libbar (soname 1,
4955 path /usr/lib/libbar.so.1, dependency field Depends)
4956 shlibs:Depends=libc6 (>= 2.2.2-2)
4958 You can then run <prgn>ldd</prgn> on the binary to find the
4959 full location of the library concerned:
4960 <example compact="compact">
4962 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4963 libc.so.6 => /lib/libc.so.6 (0x40032000)
4964 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4966 So the <prgn>foo</prgn> binary depends on the
4967 <prgn>libbar</prgn> shared library, but no package seems to
4968 provide a <file>*.shlibs</file> file handling
4969 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4970 determine the package responsible:
4971 <example compact="compact">
4972 $ dpkg -S /usr/lib/libbar.so.1
4973 bar1: /usr/lib/libbar.so.1
4974 $ dpkg -s bar1 | grep Version
4977 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4978 is the one we are using. Now we can file a bug against the
4979 <tt>bar1</tt> package and create our own
4980 <file>debian/shlibs.local</file> to locally fix the problem.
4981 Including the following line into your
4982 <file>debian/shlibs.local</file> file:
4983 <example compact="compact">
4984 libbar 1 bar1 (>= 1.0-1)
4986 should allow the package build to work.
4990 As soon as the maintainer of <tt>bar1</tt> provides a
4991 correct <file>shlibs</file> file, you should remove this line
4992 from your <file>debian/shlibs.local</file> file. (You should
4993 probably also then have a versioned <tt>Build-Depends</tt>
4994 on <tt>bar1</tt> to help ensure that others do not have the
4995 same problem building your package.)
5004 <chapt id="opersys"><heading>The Operating System</heading>
5007 <heading>Filesystem hierarchy</heading>
5011 <heading>Filesystem Structure</heading>
5014 The location of all installed files and directories must
5015 comply with the Filesystem Hierarchy Standard (FHS),
5016 version 2.1, except where doing so would violate other
5017 terms of Debian Policy. The version of this document
5018 referred here can be found in the <tt>debian-policy</tt>
5020 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5021 name="FHS (Debian copy)"> alongside this manual (or, if
5022 you have the <package>debian-policy</package> installed,
5024 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5025 (local copy)">). The
5026 latest version, which may be a more recent version, may
5028 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5029 Specific questions about following the standard may be
5030 asked on the <tt>debian-devel</tt> mailing list, or
5031 referred to the FHS mailing list (see the
5032 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5038 <heading>Site-specific programs</heading>
5041 As mandated by the FHS, packages must not place any
5042 files in <file>/usr/local</file>, either by putting them in
5043 the file system archive to be unpacked by <prgn>dpkg</prgn>
5044 or by manipulating them in their maintainer scripts.
5048 However, the package may create empty directories below
5049 <file>/usr/local</file> so that the system administrator knows
5050 where to place site-specific files. These directories
5051 should be removed on package removal if they are
5056 Note, that this applies only to directories <em>below</em>
5057 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5058 Packages must not create sub-directories in the directory
5059 <file>/usr/local</file> itself, except those listed in FHS,
5060 section 4.5. However, you may create directories below
5061 them as you wish. You must not remove any of the
5062 directories listed in 4.5, even if you created them.
5066 Since <file>/usr/local</file> can be mounted read-only from a
5067 remote server, these directories must be created and
5068 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5069 maintainer scripts and not be included in the
5070 <file>.deb</file> archive. These scripts must not fail if
5071 either of these operations fail.
5075 For example, the <tt>emacsen-common</tt> package could
5076 contain something like
5077 <example compact="compact">
5078 if [ ! -e /usr/local/share/emacs ]
5080 if mkdir /usr/local/share/emacs 2>/dev/null
5082 chown root:staff /usr/local/share/emacs
5083 chmod 2775 /usr/local/share/emacs
5087 in its <prgn>postinst</prgn> script, and
5088 <example compact="compact">
5089 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5090 rmdir /usr/local/share/emacs 2>/dev/null || true
5092 in the <prgn>prerm</prgn> script. (Note that this form is
5093 used to ensure that if the script is interrupted, the
5094 directory <file>/usr/local/share/emacs</file> will still be
5099 If you do create a directory in <file>/usr/local</file> for
5100 local additions to a package, you should ensure that
5101 settings in <file>/usr/local</file> take precedence over the
5102 equivalents in <file>/usr</file>.
5106 However, because <file>/usr/local</file> and its contents are
5107 for exclusive use of the local administrator, a package
5108 must not rely on the presence or absence of files or
5109 directories in <file>/usr/local</file> for normal operation.
5113 The <file>/usr/local</file> directory itself and all the
5114 subdirectories created by the package should (by default) have
5115 permissions 2775 (group-writable and set-group-id) and be
5116 owned by <tt>root.staff</tt>.
5121 <heading>The system-wide mail directory</heading>
5123 The system-wide mail directory is <file>/var/mail</file>. This
5124 directory is part of the base system and should not owned
5125 by any particular mail agents. The use of the old
5126 location <file>/var/spool/mail</file> is deprecated, even
5127 though the spool may still be physically located there.
5128 To maintain partial upgrade compatibility for systems
5129 which have <file>/var/spool/mail</file> as their physical mail
5130 spool, packages using <file>/var/mail</file> must depend on
5131 either <package>libc6</package> (>= 2.1.3-13), or on
5132 <package>base-files</package> (>= 2.2.0), or on later
5133 versions of either one of these packages.
5139 <heading>Users and groups</heading>
5142 <heading>Introduction</heading>
5144 The Debian system can be configured to use either plain or
5149 Some user ids (UIDs) and group ids (GIDs) are reserved
5150 globally for use by certain packages. Because some
5151 packages need to include files which are owned by these
5152 users or groups, or need the ids compiled into binaries,
5153 these ids must be used on any Debian system only for the
5154 purpose for which they are allocated. This is a serious
5155 restriction, and we should avoid getting in the way of
5156 local administration policies. In particular, many sites
5157 allocate users and/or local system groups starting at 100.
5161 Apart from this we should have dynamically allocated ids,
5162 which should by default be arranged in some sensible
5163 order, but the behavior should be configurable.
5167 Packages other than <tt>base-passwd</tt> must not modify
5168 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5169 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5174 <heading>UID and GID classes</heading>
5176 The UID and GID numbers are divided into classes as
5182 Globally allocated by the Debian project, the same
5183 on every Debian system. These ids will appear in
5184 the <file>passwd</file> and <file>group</file> files of all
5185 Debian systems, new ids in this range being added
5186 automatically as the <tt>base-passwd</tt> package is
5191 Packages which need a single statically allocated
5192 uid or gid should use one of these; their
5193 maintainers should ask the <tt>base-passwd</tt>
5201 Dynamically allocated system users and groups.
5202 Packages which need a user or group, but can have
5203 this user or group allocated dynamically and
5204 differently on each system, should use <tt>adduser
5205 --system</tt> to create the group and/or user.
5206 <prgn>adduser</prgn> will check for the existence of
5207 the user or group, and if necessary choose an unused
5208 id based on the ranges specified in
5209 <file>adduser.conf</file>.
5213 <tag>1000-29999:</tag>
5216 Dynamically allocated user accounts. By default
5217 <prgn>adduser</prgn> will choose UIDs and GIDs for
5218 user accounts in this range, though
5219 <file>adduser.conf</file> may be used to modify this
5224 <tag>30000-59999:</tag>
5229 <tag>60000-64999:</tag>
5232 Globally allocated by the Debian project, but only
5233 created on demand. The ids are allocated centrally
5234 and statically, but the actual accounts are only
5235 created on users' systems on demand.
5239 These ids are for packages which are obscure or
5240 which require many statically-allocated ids. These
5241 packages should check for and create the accounts in
5242 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5243 <prgn>adduser</prgn> if it has this facility) if
5244 necessary. Packages which are likely to require
5245 further allocations should have a "hole" left after
5246 them in the allocation, to give them room to
5251 <tag>65000-65533:</tag>
5259 User <tt>nobody</tt>. The corresponding gid refers
5260 to the group <tt>nogroup</tt>.
5267 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5268 not</em> be used, because it is the error return
5277 <sect id="sysvinit">
5278 <heading>System run levels and <file>init.d</file> scripts</heading>
5280 <sect1 id="/etc/init.d">
5281 <heading>Introduction</heading>
5284 The <file>/etc/init.d</file> directory contains the scripts
5285 executed by <prgn>init</prgn> at boot time and when the
5286 init state (or "runlevel") is changed (see <manref
5287 name="init" section="8">).
5291 There are at least two different, yet functionally
5292 equivalent, ways of handling these scripts. For the sake
5293 of simplicity, this document describes only the symbolic
5294 link method. However, it must not be assumed by maintainer
5295 scripts that this method is being used, and any automated
5296 manipulation of the various runlevel behaviours by
5297 maintainer scripts must be performed using
5298 <prgn>update-rc.d</prgn> as described below and not by
5299 manually installing or removing symlinks. For information
5300 on the implementation details of the other method,
5301 implemented in the <tt>file-rc</tt> package, please refer
5302 to the documentation of that package.
5306 These scripts are referenced by symbolic links in the
5307 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5308 runlevels, <prgn>init</prgn> looks in the directory
5309 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5310 execute, where <tt><var>n</var></tt> is the runlevel that
5311 is being changed to, or <tt>S</tt> for the boot-up
5316 The names of the links all have the form
5317 <file>S<var>mm</var><var>script</var></file> or
5318 <file>K<var>mm</var><var>script</var></file> where
5319 <var>mm</var> is a two-digit number and <var>script</var>
5320 is the name of the script (this should be the same as the
5321 name of the actual script in <file>/etc/init.d</file>).
5325 When <prgn>init</prgn> changes runlevel first the targets
5326 of the links whose names start with a <tt>K</tt> are
5327 executed, each with the single argument <tt>stop</tt>,
5328 followed by the scripts prefixed with an <tt>S</tt>, each
5329 with the single argument <tt>start</tt>. (The links are
5330 those in the <file>/etc/rc<var>n</var>.d</file> directory
5331 corresponding to the new runlevel.) The <tt>K</tt> links
5332 are responsible for killing services and the <tt>S</tt>
5333 link for starting services upon entering the runlevel.
5337 For example, if we are changing from runlevel 2 to
5338 runlevel 3, init will first execute all of the <tt>K</tt>
5339 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5340 all of the <tt>S</tt> prefixed scripts in that directory.
5341 The links starting with <tt>K</tt> will cause the
5342 referred-to file to be executed with an argument of
5343 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5348 The two-digit number <var>mm</var> is used to determine
5349 the order in which to run the scripts: low-numbered links
5350 have their scripts run first. For example, the
5351 <tt>K20</tt> scripts will be executed before the
5352 <tt>K30</tt> scripts. This is used when a certain service
5353 must be started before another. For example, the name
5354 server <prgn>bind</prgn> might need to be started before
5355 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5356 can set up its access lists. In this case, the script
5357 that starts <prgn>bind</prgn> would have a lower number
5358 than the script that starts <prgn>inn</prgn> so that it
5360 <example compact="compact">
5367 The two runlevels 0 (halt) and 6 (reboot) are slightly
5368 different. In these runlevels, the links with an
5369 <tt>S</tt> prefix are still called after those with a
5370 <tt>K</tt> prefix, but they too are called with the single
5371 argument <tt>stop</tt>.
5375 Also, if the script name ends <tt>.sh</tt>, the script
5376 will be sourced in runlevel <tt>S</tt> rather that being
5377 run in a forked subprocess, but will be explicitly run by
5378 <prgn>sh</prgn> in all other runlevels.
5383 <heading>Writing the scripts</heading>
5386 Packages that include daemons for system services should
5387 place scripts in <file>/etc/init.d</file> to start or stop
5388 services at boot time or during a change of runlevel.
5389 These scripts should be named
5390 <file>/etc/init.d/<var>package</var></file>, and they should
5391 accept one argument, saying what to do:
5394 <tag><tt>start</tt></tag>
5395 <item>start the service,</item>
5397 <tag><tt>stop</tt></tag>
5398 <item>stop the service,</item>
5400 <tag><tt>restart</tt></tag>
5401 <item>stop and restart the service if it's already running,
5402 otherwise start the service</item>
5404 <tag><tt>reload</tt></tag>
5405 <item><p>cause the configuration of the service to be
5406 reloaded without actually stopping and restarting
5409 <tag><tt>force-reload</tt></tag>
5410 <item>cause the configuration to be reloaded if the
5411 service supports this, otherwise restart the
5415 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5416 <tt>force-reload</tt> options should be supported by all
5417 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5422 The <file>init.d</file> scripts should ensure that they will
5423 behave sensibly if invoked with <tt>start</tt> when the
5424 service is already running, or with <tt>stop</tt> when it
5425 isn't, and that they don't kill unfortunately-named user
5426 processes. The best way to achieve this is usually to use
5427 <prgn>start-stop-daemon</prgn>.
5431 If a service reloads its configuration automatically (as
5432 in the case of <prgn>cron</prgn>, for example), the
5433 <tt>reload</tt> option of the <file>init.d</file> script
5434 should behave as if the configuration has been reloaded
5439 The <file>/etc/init.d</file> scripts must be treated as
5440 configuration files, either (if they are present in the
5441 package, that is, in the .deb file) by marking them as
5442 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5443 by managing them correctly in the maintainer scripts (see
5444 <ref id="config-files">). This is important since we want
5445 to give the local system administrator the chance to adapt
5446 the scripts to the local system, e.g., to disable a
5447 service without de-installing the package, or to specify
5448 some special command line options when starting a service,
5449 while making sure her changes aren't lost during the next
5454 These scripts should not fail obscurely when the
5455 configuration files remain but the package has been
5456 removed, as configuration files remain on the system after
5457 the package has been removed. Only when <prgn>dpkg</prgn>
5458 is executed with the <tt>--purge</tt> option will
5459 configuration files be removed. In particular, as the
5460 <file>/etc/init.d/<var>package</var></file> script itself is
5461 usually a <tt>conffile</tt>, it will remain on the system
5462 if the package is removed but not purged. Therefore, you
5463 should include a <tt>test</tt> statement at the top of the
5465 <example compact="compact">
5466 test -f <var>program-executed-later-in-script</var> || exit 0
5471 Often there are some variables in the <file>init.d</file>
5472 scripts whose values control the behaviour of the scripts,
5473 and which a system administrator is likely to want to
5474 change. As the scripts themselves are frequently
5475 <tt>conffile</tt>s, modifying them requires that the
5476 administrator merge in their changes each time the package
5477 is upgraded and the <tt>conffile</tt> changes. To ease
5478 the burden on the system administrator, such configurable
5479 values should not be placed directly in the script.
5480 Instead, they should be placed in a file in
5481 <file>/etc/default</file>, which typically will have the same
5482 base name as the <file>init.d</file> script. This extra file
5483 should be sourced by the script when the script runs. It
5484 must contain only variable settings and comments in POSIX
5485 <prgn>sh</prgn> format. It may either be a
5486 <tt>conffile</tt> or a configuration file maintained by
5487 the package maintainer scripts. See <ref id="config-files">
5492 To ensure that vital configurable values are always
5493 available, the <file>init.d</file> script should set default
5494 values for each of the shell variables it uses, either
5495 before sourcing the <file>/etc/default/</file> file or
5496 afterwards using something like the <tt>:
5497 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5498 script must behave sensibly and not fail if the
5499 <file>/etc/default</file> file is deleted.
5504 <heading>Interfacing with the initscript system</heading>
5507 Maintainers should use the abstraction layer provided by
5508 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5509 programs to deal with initscripts in their packages'
5510 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5511 and <prgn>postrm</prgn>.
5515 Directly managing the /etc/rc?.d links and directly
5516 invoking the <file>/etc/init.d/</file> initscripts should
5517 be done only by packages providing the initscript
5518 subsystem (such as <prgn>sysv-rc</prgn> and
5519 <prgn>file-rc</prgn>).
5523 <heading>Managing the links</heading>
5526 The program <prgn>update-rc.d</prgn> is provided for
5527 package maintainers to arrange for the proper creation and
5528 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5529 or their functional equivalent if another method is being
5530 used. This may be used by maintainers in their packages'
5531 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5535 You must not include any <file>/etc/rc<var>n</var>.d</file>
5536 symbolic links in the actual archive or manually create or
5537 remove the symbolic links in maintainer scripts; you must
5538 use the <prgn>update-rc.d</prgn> program instead. (The
5539 former will fail if an alternative method of maintaining
5540 runlevel information is being used.) You must not include
5541 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5542 in the archive either. (Only the <tt>sysvinit</tt>
5547 By default <prgn>update-rc.d</prgn> will start services in
5548 each of the multi-user state runlevels (2, 3, 4, and 5)
5549 and stop them in the halt runlevel (0), the single-user
5550 runlevel (1) and the reboot runlevel (6). The system
5551 administrator will have the opportunity to customize
5552 runlevels by simply adding, moving, or removing the
5553 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5554 symbolic links are being used, or by modifying
5555 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5560 To get the default behavior for your package, put in your
5561 <prgn>postinst</prgn> script
5562 <example compact="compact">
5563 update-rc.d <var>package</var> defaults
5565 and in your <prgn>postrm</prgn>
5566 <example compact="compact">
5567 if [ "$1" = purge ]; then
5568 update-rc.d <var>package</var> remove
5570 </example>. Note that if your package changes runlevels
5571 or priority, you may have to remove and recreate the links,
5572 since otherwise the old links may persist. Refer to the
5573 documentation of <prgn>update-rc.d</prgn>.
5577 This will use a default sequence number of 20. If it does
5578 not matter when or in which order the <file>init.d</file>
5579 script is run, use this default. If it does, then you
5580 should talk to the maintainer of the <prgn>sysvinit</prgn>
5581 package or post to <tt>debian-devel</tt>, and they will
5582 help you choose a number.
5586 For more information about using <tt>update-rc.d</tt>,
5587 please consult its man page <manref name="update-rc.d"
5593 <heading>Running initscripts</heading>
5595 The program <prgn>invoke-rc.d</prgn> is provided to make
5596 it easier for package maintainers to properly invoke an
5597 initscript, obeying runlevel and other locally-defined
5598 constraints that might limit a package's right to start,
5599 stop and otherwise manage services. This program may be
5600 used by maintainers in their packages' scripts.
5604 The use of <prgn>invoke-rc.d</prgn> to invoke the
5605 <file>/etc/init.d/*</file> initscripts is strongly
5606 recommended<footnote>
5607 In the future, the use of invoke-rc.d to invoke
5608 initscripts shall be made mandatory. Maintainers are
5609 advised to switch to invoke-rc.d as soon as
5611 </footnote>, instead of calling them directly.
5615 By default, <prgn>invoke-rc.d</prgn> will pass any
5616 action requests (start, stop, reload, restart...) to the
5617 <file>/etc/init.d</file> script, filtering out requests
5618 to start or restart a service out of its intended
5623 Most packages will simply need to change:
5624 <example compact="compact">/etc/init.d/<package>
5625 <action></example> in their <prgn>postinst</prgn>
5626 and <prgn>prerm</prgn> scripts to:
5627 <example compact="compact">
5628 if command -v invoke-rc.d >/dev/null 2>&1; then
5629 invoke-rc.d <var>package</var> <action>
5631 /etc/init.d/<var>package</var> <action>
5637 A package should register its initscript services using
5638 <prgn>update-rc.d</prgn> before it tries to invoke them
5639 using <prgn>invoke-rc.d</prgn>. Invocation of
5640 unregistered services may fail.
5644 For more information about using
5645 <prgn>invoke-rc.d</prgn>, please consult its man page
5646 <manref name="invoke-rc.d" section="8">.
5652 <heading>Boot-time initialization</heading>
5655 There used to be another directory, <file>/etc/rc.boot</file>,
5656 which contained scripts which were run once per machine
5657 boot. This has been deprecated in favour of links from
5658 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5659 described in <ref id="/etc/init.d">. Packages must not
5660 place files in <file>/etc/rc.boot</file>.
5665 <heading>Example</heading>
5668 The <prgn>bind</prgn> DNS (nameserver) package wants to
5669 make sure that the nameserver is running in multiuser
5670 runlevels, and is properly shut down with the system. It
5671 puts a script in <file>/etc/init.d</file>, naming the script
5672 appropriately <tt>bind</tt>. As you can see, the script
5673 interprets the argument <tt>reload</tt> to send the
5674 nameserver a <tt>HUP</tt> signal (causing it to reload its
5675 configuration); this way the system administrator can say
5676 <tt>/etc/init.d/bind reload</tt> to reload the name
5677 server. The script has one configurable value, which can
5678 be used to pass parameters to the named program at
5679 startup; this value is read from
5680 <file>/etc/default/bind</file> (see below).
5684 <example compact="compact">
5687 # Original version by Robert Leslie
5688 # <rob@mars.org>, edited by iwj and cs
5690 test -x /usr/sbin/named || exit 0
5692 # Source defaults file.
5694 if [ -f /etc/default/bind ]; then
5701 echo -n "Starting domain name service: named"
5702 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5707 echo -n "Stopping domain name service: named"
5708 start-stop-daemon --stop --quiet \
5709 --pidfile /var/run/named.pid --exec /usr/sbin/named
5713 echo -n "Restarting domain name service: named"
5714 start-stop-daemon --stop --quiet --oknodo \
5715 --pidfile /var/run/named.pid --exec /usr/sbin/named
5716 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5720 force-reload|reload)
5721 echo -n "Reloading configuration of domain name service: named"
5722 start-stop-daemon --stop --signal 1 --quiet \
5723 --pidfile /var/run/named.pid --exec /usr/sbin/named
5727 echo "Usage: /etc/init.d/bind " \
5728 " {start|stop|restart|reload|force-reload}" >&2
5738 Complementing the above init script is a configuration
5739 file <file>/etc/default/bind</file>, which contains
5740 configurable parameters used by the script. This would be
5741 created by the <prgn>postinst</prgn> script if it was not
5742 already present, and removed on purge by the
5743 <prgn>postrm</prgn> script.
5744 <example compact="compact">
5745 # Specified parameters to pass to named. See named(8).
5746 # You may uncomment the following line, and edit to taste.
5752 Another example on which you can base your
5753 <file>/etc/init.d</file> scripts is found in
5754 <file>/etc/init.d/skeleton</file>.
5758 If this package is happy with the default setup from
5759 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5760 and having named running in all runlevels, it can say in
5761 its <prgn>postinst</prgn>:
5762 <example compact="compact">
5763 update-rc.d bind defaults >/dev/null
5765 And in its <prgn>postrm</prgn>, to remove the links when the
5767 <example compact="compact">
5768 if [ "$1" = purge ]; then
5769 update-rc.d bind remove >/dev/null
5777 <heading>Console messages from <file>init.d</file> scripts</heading>
5780 This section describes the formats to be used for messages
5781 written to standard output by the <file>/etc/init.d</file>
5782 scripts. The intent is to improve the consistency of
5783 Debian's startup and shutdown look and feel. For this
5784 reason, please look very carefully at the details. We want
5785 the messages to have the same format in terms of wording,
5786 spaces, punctuation and case of letters.
5790 Here is a list of overall rules that you should use when you
5791 create output messages. They can be useful if you have a
5792 non-standard message that is not covered specifically in the
5799 Every message should fit in one line (fewer than 80
5800 characters), start with a capital letter and end with
5801 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5805 If you want to express that the computer is working on
5806 something (that is, performing a specific task, not
5807 starting or stopping a program), we use an "ellipsis"
5808 (three dots: <tt>...</tt>). Note that we don't insert
5809 spaces before or after the dots. If the task has been
5810 completed we write <tt>done.</tt> and a line feed.
5814 Design your messages as if the computer is telling you
5815 what he is doing (let him be polite :-), but don't
5816 mention "him" directly. For example, if you think of
5818 <example compact="compact">
5819 I'm starting network daemons: nfsd mountd.
5822 <example compact="compact">
5823 Starting network daemons: nfsd mountd.
5830 There are standard message formats for the following
5831 situations. They should be used by the <tt>init.d</tt>
5838 <p>When daemons are started</p>
5841 If your script starts one or more daemons, the output
5842 should look like this (a single line, no leading
5844 <example compact="compact">
5845 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5847 The <var>description</var> should describe the
5848 subsystem the daemon or set of daemons are part of,
5849 while <var>daemon-1</var> up to <var>daemon-n</var>
5850 denote each daemon's name (typically the file name of
5855 For example, the output of <file>/etc/init.d/lpd</file>
5857 <example compact="compact">
5858 Starting printer spooler: lpd.
5863 This can be achieved by saying
5864 <example compact="compact">
5865 echo -n "Starting printer spooler: lpd"
5866 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5869 in the script. If you have more than one daemon to
5870 start, you should do the following:
5871 <example compact="compact">
5872 echo -n "Starting remote file system services:"
5873 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5874 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5875 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5878 This makes it possible for the user to see what takes
5879 so long and when the final daemon has been started.
5880 You should be careful where to put spaces: in the
5881 example above the system administrator can easily
5882 comment out a line if he don't wants to start a
5883 specific daemon, while the displayed message still
5889 <p>When a system parameter is being set</p>
5892 If you have to set up different system parameters
5893 during the system boot, you should use this format:
5894 <example compact="compact">
5895 Setting <var>parameter</var> to "<var>value</var>".
5900 You can use a statement such as the following to get
5902 <example compact="compact">
5903 echo "Setting DNS domainname to \"$domainname\"."
5908 Note that the same symbol (<tt>"</tt>) is used for the left
5909 and right quotation marks. A grave accent (<tt>`</tt>) is
5910 not a quote character; neither is an apostrophe
5916 <p>When a daemon is stopped or restarted</p>
5919 When you stop or restart a daemon, you should issue a
5920 message identical to the startup message, except that
5921 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5922 or <tt>Restarting</tt> respectively.
5926 For example, stopping the printer daemon will like
5928 <example compact="compact">
5929 Stopping printer spooler: lpd.
5935 <p>When something is executed</p>
5938 There are several examples where you have to run a
5939 program at system startup or shutdown to perform a
5940 specific task, for example, setting the system's clock
5941 using <prgn>netdate</prgn> or killing all processes
5942 when the system shuts down. Your message should look
5944 <example compact="compact">
5945 Doing something very useful...done.
5947 You should print the <tt>done.</tt> immediately after
5948 the job has been completed, so that the user is
5949 informed why she has to wait. You can get this
5951 <example compact="compact">
5952 echo -n "Doing something very useful..."
5961 <p>When the configuration is reloaded</p>
5964 When a daemon is forced to reload its configuration
5965 files you should use the following format:
5966 <example compact="compact">
5967 Reloading <var>description</var> configuration...done.
5969 where <var>description</var> is the same as in the
5970 daemon starting message.
5978 <heading>Cron jobs</heading>
5981 Packages must not modify the configuration file
5982 <file>/etc/crontab</file>, and they must not modify the files in
5983 <file>/var/spool/cron/crontabs</file>.</p>
5986 If a package wants to install a job that has to be executed
5987 via cron, it should place a file with the name of the
5988 package in one or more of the following directories:
5989 <example compact="compact">
5994 As these directory names imply, the files within them are
5995 executed on a daily, weekly, or monthly basis,
5996 respectively. The exact times are listed in
5997 <file>/etc/crontab</file>.</p>
6000 All files installed in any of these directories must be
6001 scripts (e.g., shell scripts or Perl scripts) so that they
6002 can easily be modified by the local system administrator.
6003 In addition, they should be treated as configuration
6008 If a certain job has to be executed more frequently than
6009 daily, the package should install a file
6010 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6011 same syntax as <file>/etc/crontab</file> and is processed by
6012 <prgn>cron</prgn> automatically. The file must also be
6013 treated as a configuration file. (Note that entries in the
6014 <file>/etc/cron.d</file> directory are not handled by
6015 <prgn>anacron</prgn>. Thus, you should only use this
6016 directory for jobs which may be skipped if the system is not
6020 The scripts or crontab entries in these directories should
6021 check if all necessary programs are installed before they
6022 try to execute them. Otherwise, problems will arise when a
6023 package was removed but not purged since configuration files
6024 are kept on the system in this situation.</p>
6028 <heading>Menus</heading>
6031 The Debian <tt>menu</tt> package provides a standard
6032 interface between packages providing applications and
6033 <em>menu programs</em> (either X window managers or
6034 text-based menu programs such as <prgn>pdmenu</prgn>).
6038 All packages that provide applications that need not be
6039 passed any special command line arguments for normal
6040 operation should register a menu entry for those
6041 applications, so that users of the <tt>menu</tt> package
6042 will automatically get menu entries in their window
6043 managers, as well in shells like <tt>pdmenu</tt>.
6047 Menu entries should follow the current menu policy.
6051 The menu policy can be found in the <tt>menu-policy</tt>
6052 files in the <tt>debian-policy</tt> package.
6053 It is also available from the Debian web mirrors at
6054 <tt><url name="/doc/packaging-manuals/menu-policy/"
6055 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6059 Please also refer to the <em>Debian Menu System</em>
6060 documentation that comes with the <package>menu</package>
6061 package for information about how to register your
6067 <heading>Multimedia handlers</heading>
6070 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6071 is a mechanism for encoding files and data streams and
6072 providing meta-information about them, in particular their
6073 type (e.g. audio or video) and format (e.g. PNG, HTML,
6078 Registration of MIME type handlers allows programs like mail
6079 user agents and web browsers to invoke these handlers to
6080 view, edit or display MIME types they don't support directly.
6084 Packages which provide the ability to view/show/play,
6085 compose, edit or print MIME types should register themselves
6086 as such following the current MIME support policy.
6090 The MIME support policy can be found in the <tt>mime-policy</tt>
6091 files in the <tt>debian-policy</tt> package.
6092 It is also available from the Debian web mirrors at
6093 <tt><url name="/doc/packaging-manuals/mime-policy/"
6094 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6100 <heading>Keyboard configuration</heading>
6103 To achieve a consistent keyboard configuration so that all
6104 applications interpret a keyboard event the same way, all
6105 programs in the Debian distribution must be configured to
6106 comply with the following guidelines.
6110 The following keys must have the specified interpretations:
6113 <tag><tt><--</tt></tag>
6114 <item>delete the character to the left of the cursor</item>
6116 <tag><tt>Delete</tt></tag>
6117 <item>delete the character to the right of the cursor</item>
6119 <tag><tt>Control+H</tt></tag>
6120 <item>emacs: the help prefix</item>
6123 The interpretation of any keyboard events should be
6124 independent of the terminal that is used, be it a virtual
6125 console, an X terminal emulator, an rlogin/telnet session,
6130 The following list explains how the different programs
6131 should be set up to achieve this:
6137 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6141 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6145 X translations are set up to make
6146 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6147 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6148 is the vt220 escape code for the "delete character"
6149 key). This must be done by loading the X resources
6150 using <prgn>xrdb</prgn> on all local X displays, not
6151 using the application defaults, so that the
6152 translation resources used correspond to the
6153 <prgn>xmodmap</prgn> settings.
6157 The Linux console is configured to make
6158 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6159 generate <tt>ESC [ 3 ~</tt>.
6163 X applications are configured so that <tt><</tt>
6164 deletes left, and <tt>Delete</tt> deletes right. Motif
6165 applications already work like this.
6169 Terminals should have <tt>stty erase ^?</tt> .
6173 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6174 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6175 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6179 Emacs is programmed to map <tt>KB_Backspace</tt> or
6180 the <tt>stty erase</tt> character to
6181 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6182 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6183 <tt>^H</tt> to <tt>help</tt> as always.
6187 Other applications use the <tt>stty erase</tt>
6188 character and <tt>kdch1</tt> for the two delete keys,
6189 with ASCII DEL being "delete previous character" and
6190 <tt>kdch1</tt> being "delete character under
6198 This will solve the problem except for the following
6205 Some terminals have a <tt><--</tt> key that cannot
6206 be made to produce anything except <tt>^H</tt>. On
6207 these terminals Emacs help will be unavailable on
6208 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6209 character takes precedence in Emacs, and has been set
6210 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6211 available) can be used instead.
6215 Some operating systems use <tt>^H</tt> for <tt>stty
6216 erase</tt>. However, modern telnet versions and all
6217 rlogin versions propagate <tt>stty</tt> settings, and
6218 almost all UNIX versions honour <tt>stty erase</tt>.
6219 Where the <tt>stty</tt> settings are not propagated
6220 correctly, things can be made to work by using
6221 <tt>stty</tt> manually.
6225 Some systems (including previous Debian versions) use
6226 <prgn>xmodmap</prgn> to arrange for both
6227 <tt><--</tt> and <tt>Delete</tt> to generate
6228 <tt>KB_Delete</tt>. We can change the behavior of
6229 their X clients using the same X resources that we use
6230 to do it for our own clients, or configure our clients
6231 using their resources when things are the other way
6232 around. On displays configured like this
6233 <tt>Delete</tt> will not work, but <tt><--</tt>
6238 Some operating systems have different <tt>kdch1</tt>
6239 settings in their <tt>terminfo</tt> database for
6240 <tt>xterm</tt> and others. On these systems the
6241 <tt>Delete</tt> key will not work correctly when you
6242 log in from a system conforming to our policy, but
6243 <tt><--</tt> will.
6250 <heading>Environment variables</heading>
6253 A program must not depend on environment variables to get
6254 reasonable defaults. (That's because these environment
6255 variables would have to be set in a system-wide
6256 configuration file like <file>/etc/profile</file>, which is not
6257 supported by all shells.)
6261 If a program usually depends on environment variables for its
6262 configuration, the program should be changed to fall back to
6263 a reasonable default configuration if these environment
6264 variables are not present. If this cannot be done easily
6265 (e.g., if the source code of a non-free program is not
6266 available), the program must be replaced by a small
6267 "wrapper" shell script which sets the environment variables
6268 if they are not already defined, and calls the original program.
6272 Here is an example of a wrapper script for this purpose:
6274 <example compact="compact">
6276 BAR=${BAR:-/var/lib/fubar}
6278 exec /usr/lib/foo/foo "$@"
6283 Furthermore, as <file>/etc/profile</file> is a configuration
6284 file of the <prgn>base-files</prgn> package, other packages must
6285 not put any environment variables or other commands into that
6290 <sect id="doc-base">
6291 <heading>Registering Documents using doc-base</heading>
6294 The <package>doc-base</package> package implements a
6295 flexible mechanism for handling and presenting
6296 documentation. The recommended practice is for every Debian
6297 package that provides online documentation (other than just
6298 manual pages) to register these documents with
6299 <package>doc-base</package> by installing a
6300 <package>doc-base</package> control file via the
6301 <prgn/install-docs/ script at installation time and
6302 de-register the manuals again when the package is removed.
6305 Please refer to the documentation that comes with the
6306 <package>doc-base</package> package for information and
6315 <heading>Files</heading>
6318 <heading>Binaries</heading>
6321 Two different packages must not install programs with
6322 different functionality but with the same filenames. (The
6323 case of two programs having the same functionality but
6324 different implementations is handled via "alternatives" or
6325 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6326 <ref id="conflicts"> respectively.) If this case happens,
6327 one of the programs must be renamed. The maintainers should
6328 report this to the <tt>debian-devel</tt> mailing list and
6329 try to find a consensus about which program will have to be
6330 renamed. If a consensus cannot be reached, <em>both</em>
6331 programs must be renamed.
6335 By default, when a package is being built, any binaries
6336 created should include debugging information, as well as
6337 being compiled with optimization. You should also turn on
6338 as many reasonable compilation warnings as possible; this
6339 makes life easier for porters, who can then look at build
6340 logs for possible problems. For the C programming language,
6341 this means the following compilation parameters should be
6343 <example compact="compact">
6345 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6347 install -s # (or use strip on the files in debian/tmp)
6352 Note that by default all installed binaries should be stripped,
6353 either by using the <tt>-s</tt> flag to
6354 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6355 the binaries after they have been copied into
6356 <file>debian/tmp</file> but before the tree is made into a
6361 Although binaries in the build tree should be compiled with
6362 debugging information by default, it can often be difficult
6363 to debug programs if they are also subjected to compiler
6364 optimization. For this reason, it is recommended to support
6365 the standardized environment
6366 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6367 contain several flags to change how a package is compiled
6375 The presence of this string means that the package
6376 should be compiled with a minimum of optimization.
6377 For C programs, it is best to add <tt>-O0</tt>
6378 to <tt>CFLAGS</tt> (although this is usually the
6379 default). Some programs might fail to build or run at
6380 this level of optimization; it may be necessary to
6381 use <tt>-O1</tt>, for example.
6385 This string means that the debugging symbols should
6386 not be stripped from the binary during installation,
6387 so that debugging information may be included in the package.
6393 The following makefile snippet is an example of how one may
6394 implement the build options; you will probably have to
6395 massage this example in order to make it work for your
6397 <example compact="compact">
6400 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6401 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6402 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6403 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6405 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6410 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6411 INSTALL_PROGRAM += -s
6417 It is up to the package maintainer to decide what
6418 compilation options are best for the package. Certain
6419 binaries (such as computationally-intensive programs) will
6420 function better with certain flags (<tt>-O3</tt>, for
6421 example); feel free to use them. Please use good judgment
6422 here. Don't use flags for the sake of it; only use them
6423 if there is good reason to do so. Feel free to override
6424 the upstream author's ideas about which compilation
6425 options are best: they are often inappropriate for our
6431 <sect id="libraries">
6432 <heading>Libraries</heading>
6435 The shared version of a library must be compiled with
6436 <tt>-fPIC</tt>, and the static version must not be. In other
6437 words, each source unit (<tt>*.c</tt>, for example, for C files)
6438 will need to be compiled twice.
6442 You must specify the gcc option <tt>-D_REENTRANT</tt>
6443 when building a library (either static or shared) to make
6444 the library compatible with LinuxThreads.
6448 Although not enforced by the build tools, shared libraries
6449 must be linked against all libraries that they use symbols from
6450 in the same way that binaries are. This ensures the correct
6451 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6452 system and guarantees that all libraries can be safely opened
6453 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6454 option <tt>-Wl,-z,defs</tt> when building a shared library.
6455 Since this option enforces symbol resolution at build time,
6456 a missing library reference will be caught early as a fatal
6461 All installed shared libraries should be stripped with
6462 <example compact="compact">
6463 strip --strip-unneeded <var>your-lib</var>
6465 (The option <tt>--strip-unneeded</tt> makes
6466 <prgn>strip</prgn> remove only the symbols which aren't
6467 needed for relocation processing.) Shared libraries can
6468 function perfectly well when stripped, since the symbols for
6469 dynamic linking are in a separate part of the ELF object
6471 You might also want to use the options
6472 <tt>--remove-section=.comment</tt> and
6473 <tt>--remove-section=.note</tt> on both shared libraries
6474 and executables, and <tt>--strip-debug</tt> on static
6480 Note that under some circumstances it may be useful to
6481 install a shared library unstripped, for example when
6482 building a separate package to support debugging.
6486 Shared object files (often <file>.so</file> files) that are not
6487 public libraries, that is, they are not meant to be linked
6488 to by third party executables (binaries of other packages),
6489 should be installed in subdirectories of the
6490 <file>/usr/lib</file> directory. Such files are exempt from the
6491 rules that govern ordinary shared libraries, except that
6492 they must not be installed executable and should be
6494 A common example are the so-called "plug-ins",
6495 internal shared objects that are dynamically loaded by
6496 programs using <manref name="dlopen" section="3">.
6501 Packages containing shared libraries that may be linked to
6502 by other packages' binaries, but which for some
6503 <em>compelling</em> reason can not be installed in
6504 <file>/usr/lib</file> directory, may install the shared library
6505 files in subdirectories of the <file>/usr/lib</file> directory,
6506 in which case they should arrange to add that directory in
6507 <file>/etc/ld.so.conf</file> in the package's post-installation
6508 script, and remove it in the package's post-removal script.
6512 An ever increasing number of packages are using
6513 <prgn>libtool</prgn> to do their linking. The latest GNU
6514 libtools (>= 1.3a) can take advantage of the metadata in the
6515 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6516 files). The main advantage of <prgn>libtool</prgn>'s
6517 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6518 store and subsequently access metadata with respect to the
6519 libraries it builds. <prgn>libtool</prgn> will search for
6520 those files, which contain a lot of useful information about
6521 a library (such as library dependency information for static
6522 linking). Also, they're <em>essential</em> for programs
6523 using <tt>libltdl</tt>.<footnote>
6524 Although <prgn>libtool</prgn> is fully capable of
6525 linking against shared libraries which don't have
6526 <tt>.la</tt> files, as it is a mere shell script it can
6527 add considerably to the build time of a
6528 <prgn>libtool</prgn>-using package if that shell script
6529 has to derive all this information from first principles
6530 for each library every time it is linked. With the
6531 advent of <prgn>libtool</prgn> version 1.4 (and to a
6532 lesser extent <prgn>libtool</prgn> version 1.3), the
6533 <file>.la</file> files also store information about
6534 inter-library dependencies which cannot necessarily be
6535 derived after the <file>.la</file> file is deleted.
6540 Packages that use <prgn>libtool</prgn> to create shared
6541 libraries should include the <file>.la</file> files in the
6542 <tt>-dev</tt> package, unless the package relies on
6543 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6544 the <tt>.la</tt> files must go in the run-time library
6549 You must make sure that you use only released versions of
6550 shared libraries to build your packages; otherwise other
6551 users will not be able to run your binaries
6552 properly. Producing source packages that depend on
6553 unreleased compilers is also usually a bad
6560 <heading>Shared libraries</heading>
6562 This section has moved to <ref id="sharedlibs">.
6568 <heading>Scripts</heading>
6571 All command scripts, including the package maintainer
6572 scripts inside the package and used by <prgn>dpkg</prgn>,
6573 should have a <tt>#!</tt> line naming the shell to be used
6578 In the case of Perl scripts this should be
6579 <tt>#!/usr/bin/perl</tt>.
6583 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6584 should almost certainly start with <tt>set -e</tt> so that
6585 errors are detected. Every script should use
6586 <tt>set -e</tt> or check the exit status of <em>every</em>
6591 The standard shell interpreter <file>/bin/sh</file> can be a
6592 symbolic link to any POSIX compatible shell, if <tt>echo
6593 -n</tt> does not generate a newline.<footnote>
6594 Debian policy specifies POSIX behavior for
6595 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6596 use in the Linux community (in particular including this
6597 policy, the Linux kernel source, many Debian scripts,
6598 etc.). This <tt>echo -n</tt> mechanism is valid but not
6599 required under POSIX, hence this explicit addition.
6600 Also, rumour has it that this shall be mandated under
6603 Thus, shell scripts specifying <file>/bin/sh</file> as
6604 interpreter should only use POSIX features. If a script
6605 requires non-POSIX features from the shell interpreter, the
6606 appropriate shell must be specified in the first line of the
6607 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6608 depend on the package providing the shell (unless the shell
6609 package is marked "Essential", as in the case of
6614 You may wish to restrict your script to POSIX features when
6615 possible so that it may use <file>/bin/sh</file> as its
6616 interpreter. If your script works with <prgn>dash</prgn>
6617 (originally called <prgn>ash</prgn>), it's probably POSIX
6618 compliant, but if you are in doubt, use
6619 <file>/bin/bash</file>.
6623 Perl scripts should check for errors when making any
6624 system calls, including <tt>open</tt>, <tt>print</tt>,
6625 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6629 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6630 scripting languages. See <em>Csh Programming Considered
6631 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6632 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
6633 If an upstream package comes with <prgn>csh</prgn> scripts
6634 then you must make sure that they start with
6635 <tt>#!/bin/csh</tt> and make your package depend on the
6636 <prgn>c-shell</prgn> virtual package.
6640 Any scripts which create files in world-writeable
6641 directories (e.g., in <file>/tmp</file>) must use a
6642 mechanism which will fail if a file with the same name
6647 The Debian base system provides the <prgn>tempfile</prgn>
6648 and <prgn>mktemp</prgn> utilities for use by scripts for
6655 <heading>Symbolic links</heading>
6658 In general, symbolic links within a top-level directory
6659 should be relative, and symbolic links pointing from one
6660 top-level directory into another should be absolute. (A
6661 top-level directory is a sub-directory of the root
6662 directory <file>/</file>.)
6666 In addition, symbolic links should be specified as short as
6667 possible, i.e., link targets like <file>foo/../bar</file> are
6672 Note that when creating a relative link using
6673 <prgn>ln</prgn> it is not necessary for the target of the
6674 link to exist relative to the working directory you're
6675 running <prgn>ln</prgn> from, nor is it necessary to change
6676 directory to the directory where the link is to be made.
6677 Simply include the string that should appear as the target
6678 of the link (this will be a pathname relative to the
6679 directory in which the link resides) as the first argument
6684 For example, in your <prgn>Makefile</prgn> or
6685 <file>debian/rules</file>, you can do things like:
6686 <example compact="compact">
6687 ln -fs gcc $(prefix)/bin/cc
6688 ln -fs gcc debian/tmp/usr/bin/cc
6689 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6690 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6695 A symbolic link pointing to a compressed file should always
6696 have the same file extension as the referenced file. (For
6697 example, if a file <file>foo.gz</file> is referenced by a
6698 symbolic link, the filename of the link has to end with
6699 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6704 <heading>Device files</heading>
6707 Packages must not include device files in the package file
6712 If a package needs any special device files that are not
6713 included in the base system, it must call
6714 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6715 after notifying the user<footnote>
6716 This notification could be done via a (low-priority)
6717 debconf message, or an echo (printf) statement.
6722 Packages must not remove any device files in the
6723 <prgn>postrm</prgn> or any other script. This is left to the
6724 system administrator.
6728 Debian uses the serial devices
6729 <file>/dev/ttyS*</file>. Programs using the old
6730 <file>/dev/cu*</file> devices should be changed to use
6731 <file>/dev/ttyS*</file>.
6735 <sect id="config-files">
6736 <heading>Configuration files</heading>
6739 <heading>Definitions</heading>
6743 <tag>configuration file</tag>
6745 A file that affects the operation of a program, or
6746 provides site- or host-specific information, or
6747 otherwise customizes the behavior of a program.
6748 Typically, configuration files are intended to be
6749 modified by the system administrator (if needed or
6750 desired) to conform to local policy or to provide
6751 more useful site-specific behavior.
6754 <tag><tt>conffile</tt></tag>
6756 A file listed in a package's <tt>conffiles</tt>
6757 file, and is treated specially by <prgn>dpkg</prgn>
6758 (see <ref id="configdetails">).
6764 The distinction between these two is important; they are
6765 not interchangeable concepts. Almost all
6766 <tt>conffile</tt>s are configuration files, but many
6767 configuration files are not <tt>conffiles</tt>.
6771 Note that a script that embeds configuration information
6772 (such as most of the files in <file>/etc/default</file> and
6773 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6774 configuration file and should be treated as such.
6779 <heading>Location</heading>
6782 Any configuration files created or used by your package
6783 must reside in <file>/etc</file>. If there are several,
6784 consider creating a subdirectory of <file>/etc</file>
6785 named after your package.
6789 If your package creates or uses configuration files
6790 outside of <file>/etc</file>, and it is not feasible to modify
6791 the package to use <file>/etc</file> directly, put the files
6792 in <file>/etc</file> and create symbolic links to those files
6793 from the location that the package requires.
6798 <heading>Behavior</heading>
6801 Configuration file handling must conform to the following
6803 <list compact="compact">
6805 local changes must be preserved during a package
6809 configuration files must be preserved when the
6810 package is removed, and only deleted when the
6817 The easy way to achieve this behavior is to make the
6818 configuration file a <tt>conffile</tt>. This is
6819 appropriate only if it is possible to distribute a default
6820 version that will work for most installations, although
6821 some system administrators may choose to modify it. This
6822 implies that the default version will be part of the
6823 package distribution, and must not be modified by the
6824 maintainer scripts during installation (or at any other
6829 In order to ensure that local changes are preserved
6830 correctly, no package may contain or make hard links to
6831 conffiles.<footnote>
6832 Rationale: There are two problems with hard links.
6833 The first is that some editors break the link while
6834 editing one of the files, so that the two files may
6835 unwittingly become unlinked and different. The second
6836 is that <prgn>dpkg</prgn> might break the hard link
6837 while upgrading <tt>conffile</tt>s.
6842 The other way to do it is via the maintainer scripts. In
6843 this case, the configuration file must not be listed as a
6844 <tt>conffile</tt> and must not be part of the package
6845 distribution. If the existence of a file is required for
6846 the package to be sensibly configured it is the
6847 responsibility of the package maintainer to provide
6848 maintainer scripts which correctly create, update and
6849 maintain the file and remove it on purge. (See <ref
6850 id="maintainerscripts"> for more information.) These
6851 scripts must be idempotent (i.e., must work correctly if
6852 <prgn>dpkg</prgn> needs to re-run them due to errors
6853 during installation or removal), must cope with all the
6854 variety of ways <prgn>dpkg</prgn> can call maintainer
6855 scripts, must not overwrite or otherwise mangle the user's
6856 configuration without asking, must not ask unnecessary
6857 questions (particularly during upgrades), and otherwise be
6862 The scripts are not required to configure every possible
6863 option for the package, but only those necessary to get
6864 the package running on a given system. Ideally the
6865 sysadmin should not have to do any configuration other
6866 than that done (semi-)automatically by the
6867 <prgn>postinst</prgn> script.
6871 A common practice is to create a script called
6872 <file><var>package</var>-configure</file> and have the
6873 package's <prgn>postinst</prgn> call it if and only if the
6874 configuration file does not already exist. In certain
6875 cases it is useful for there to be an example or template
6876 file which the maintainer scripts use. Such files should
6877 be in <file>/usr/share/<var>package</var></file> or
6878 <file>/usr/lib/<var>package</var></file> (depending on whether
6879 they are architecture-independent or not). There should
6880 be symbolic links to them from
6881 <file>/usr/share/doc/<var>package</var>/examples</file> if
6882 they are examples, and should be perfectly ordinary
6883 <prgn>dpkg</prgn>-handled files (<em>not</em>
6884 configuration files).
6888 These two styles of configuration file handling must
6889 not be mixed, for that way lies madness:
6890 <prgn>dpkg</prgn> will ask about overwriting the file
6891 every time the package is upgraded.
6896 <heading>Sharing configuration files</heading>
6899 Packages which specify the same file as a
6900 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6901 with each other. (This is an instance of the general rule
6902 about not sharing files. Note that neither alternatives
6903 nor diversions are likely to be appropriate in this case;
6904 in particular, <prgn>dpkg</prgn> does not handle diverted
6905 <tt>conffile</tt>s well.)
6909 The maintainer scripts must not alter a <tt>conffile</tt>
6910 of <em>any</em> package, including the one the scripts
6915 If two or more packages use the same configuration file
6916 and it is reasonable for both to be installed at the same
6917 time, one of these packages must be defined as
6918 <em>owner</em> of the configuration file, i.e., it will be
6919 the package which handles that file as a configuration
6920 file. Other packages that use the configuration file must
6921 depend on the owning package if they require the
6922 configuration file to operate. If the other package will
6923 use the configuration file if present, but is capable of
6924 operating without it, no dependency need be declared.
6928 If it is desirable for two or more related packages to
6929 share a configuration file <em>and</em> for all of the
6930 related packages to be able to modify that configuration
6931 file, then the following should be done:
6932 <enumlist compact="compact">
6934 One of the related packages (the "owning" package)
6935 will manage the configuration file with maintainer
6936 scripts as described in the previous section.
6939 The owning package should also provide a program
6940 that the other packages may use to modify the
6944 The related packages must use the provided program
6945 to make any desired modifications to the
6946 configuration file. They should either depend on
6947 the core package to guarantee that the configuration
6948 modifier program is available or accept gracefully
6949 that they cannot modify the configuration file if it
6950 is not. (This is in addition to the fact that the
6951 configuration file may not even be present in the
6958 Sometimes it's appropriate to create a new package which
6959 provides the basic infrastructure for the other packages
6960 and which manages the shared configuration files. (The
6961 <tt>sgml-base</tt> package is a good example.)
6966 <heading>User configuration files ("dotfiles")</heading>
6969 The files in <file>/etc/skel</file> will automatically be
6970 copied into new user accounts by <prgn>adduser</prgn>.
6971 No other program should reference the files in
6972 <file>/etc/skel</file>.
6976 Therefore, if a program needs a dotfile to exist in
6977 advance in <file>$HOME</file> to work sensibly, that dotfile
6978 should be installed in <file>/etc/skel</file> and treated as a
6983 However, programs that require dotfiles in order to
6984 operate sensibly are a bad thing, unless they do create
6985 the dotfiles themselves automatically.
6989 Furthermore, programs should be configured by the Debian
6990 default installation to behave as closely to the upstream
6991 default behaviour as possible.
6995 Therefore, if a program in a Debian package needs to be
6996 configured in some way in order to operate sensibly, that
6997 should be done using a site-wide configuration file placed
6998 in <file>/etc</file>. Only if the program doesn't support a
6999 site-wide default configuration and the package maintainer
7000 doesn't have time to add it may a default per-user file be
7001 placed in <file>/etc/skel</file>.
7005 <file>/etc/skel</file> should be as empty as we can make it.
7006 This is particularly true because there is no easy (or
7007 necessarily desirable) mechanism for ensuring that the
7008 appropriate dotfiles are copied into the accounts of
7009 existing users when a package is installed.
7015 <heading>Log files</heading>
7017 Log files should usually be named
7018 <file>/var/log/<var>package</var>.log</file>. If you have many
7019 log files, or need a separate directory for permission
7020 reasons (<file>/var/log</file> is writable only by
7021 <file>root</file>), you should usually create a directory named
7022 <file>/var/log/<var>package</var></file> and place your log
7027 Log files must be rotated occasionally so that they don't
7028 grow indefinitely; the best way to do this is to drop a log
7029 rotation configuration file into the directory
7030 <file>/etc/logrotate.d</file> and use the facilities provided by
7031 logrotate.<footnote>
7033 The traditional approach to log files has been to set up
7034 <em>ad hoc</em> log rotation schemes using simple shell
7035 scripts and cron. While this approach is highly
7036 customizable, it requires quite a lot of sysadmin work.
7037 Even though the original Debian system helped a little
7038 by automatically installing a system which can be used
7039 as a template, this was deemed not enough.
7043 The use of <prgn>logrotate</prgn>, a program developed
7044 by Red Hat, is better, as it centralizes log management.
7045 It has both a configuration file
7046 (<file>/etc/logrotate.conf</file>) and a directory where
7047 packages can drop their individual log rotation
7048 configurations (<file>/etc/logrotate.d</file>).
7051 Here is a good example for a logrotate config
7052 file (for more information see <manref name="logrotate"
7054 <example compact="compact">
7055 /var/log/foo/*.log {
7060 /etc/init.d/foo force-reload
7064 This rotates all files under <file>/var/log/foo</file>, saves 12
7065 compressed generations, and forces the daemon to reload its
7066 configuration information after the log rotation.
7070 Log files should be removed when the package is
7071 purged (but not when it is only removed). This should be
7072 done by the <prgn>postrm</prgn> script when it is called
7073 with the argument <tt>purge</tt> (see <ref
7074 id="removedetails">).
7079 <heading>Permissions and owners</heading>
7082 The rules in this section are guidelines for general use.
7083 If necessary you may deviate from the details below.
7084 However, if you do so you must make sure that what is done
7085 is secure and you should try to be as consistent as possible
7086 with the rest of the system. You should probably also
7087 discuss it on <prgn>debian-devel</prgn> first.
7091 Files should be owned by <tt>root.root</tt>, and made
7092 writable only by the owner and universally readable (and
7093 executable, if appropriate), that is mode 644 or 755.
7097 Directories should be mode 755 or (for group-writability)
7098 mode 2775. The ownership of the directory should be
7099 consistent with its mode: if a directory is mode 2775, it
7100 should be owned by the group that needs write access to
7105 Setuid and setgid executables should be mode 4755 or 2755
7106 respectively, and owned by the appropriate user or group.
7107 They should not be made unreadable (modes like 4711 or
7108 2711 or even 4111); doing so achieves no extra security,
7109 because anyone can find the binary in the freely available
7110 Debian package; it is merely inconvenient. For the same
7111 reason you should not restrict read or execute permissions
7112 on non-set-id executables.
7116 Some setuid programs need to be restricted to particular
7117 sets of users, using file permissions. In this case they
7118 should be owned by the uid to which they are set-id, and by
7119 the group which should be allowed to execute them. They
7120 should have mode 4754; again there is no point in making
7121 them unreadable to those users who must not be allowed to
7126 It is possible to arrange that the system administrator can
7127 reconfigure the package to correspond to their local
7128 security policy by changing the permissions on a binary:
7129 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7130 described below.<footnote>
7131 Ordinary files installed by <prgn>dpkg</prgn> (as
7132 opposed to <tt>conffile</tt>s and other similar objects)
7133 normally have their permissions reset to the distributed
7134 permissions when the package is reinstalled. However,
7135 the use of <prgn>dpkg-statoverride</prgn> overrides this
7136 default behaviour. If you use this method, you should
7137 remember to describe <prgn>dpkg-statoverride</prgn> in
7138 the package documentation; being a relatively new
7139 addition to Debian, it is probably not yet well-known.
7141 Another method you should consider is to create a group for
7142 people allowed to use the program(s) and make any setuid
7143 executables executable only by that group.
7147 If you need to create a new user or group for your package
7148 there are two possibilities. Firstly, you may need to
7149 make some files in the binary package be owned by this
7150 user or group, or you may need to compile the user or
7151 group id (rather than just the name) into the binary
7152 (though this latter should be avoided if possible, as in
7153 this case you need a statically allocated id).</p>
7156 If you need a statically allocated id, you must ask for a
7157 user or group id from the <tt>base-passwd</tt> maintainer,
7158 and must not release the package until you have been
7159 allocated one. Once you have been allocated one you must
7160 either make the package depend on a version of the
7161 <tt>base-passwd</tt> package with the id present in
7162 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7163 your package to create the user or group itself with the
7164 correct id (using <tt>adduser</tt>) in its
7165 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7166 the <prgn>postinst</prgn> is to be preferred if it is
7167 possible, otherwise a pre-dependency will be needed on the
7168 <tt>adduser</tt> package.)
7172 On the other hand, the program might be able to determine
7173 the uid or gid from the user or group name at runtime, so
7174 that a dynamically allocated id can be used. In this case
7175 you should choose an appropriate user or group name,
7176 discussing this on <prgn>debian-devel</prgn> and checking
7177 with the <package/base-passwd/ maintainer that it is unique and that
7178 they do not wish you to use a statically allocated id
7179 instead. When this has been checked you must arrange for
7180 your package to create the user or group if necessary using
7181 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7182 <prgn>postinst</prgn> script (again, the latter is to be
7183 preferred if it is possible).
7187 Note that changing the numeric value of an id associated
7188 with a name is very difficult, and involves searching the
7189 file system for all appropriate files. You need to think
7190 carefully whether a static or dynamic id is required, since
7191 changing your mind later will cause problems.
7194 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7196 This section is not intended as policy, but as a
7197 description of the use of <prgn>dpkg-statoverride</prgn>.
7201 <prgn>dpkg-statoverride</prgn> is a replacement for the
7202 deprecated <tt>suidmanager</tt> package. Packages which
7203 previously used <tt>suidmanager</tt> should have a
7204 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7205 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7206 and <tt>suidunregister</tt> should now be simply removed
7207 from the maintainer scripts.
7211 If a system administrator wishes to have a file (or
7212 directory or other such thing) installed with owner and
7213 permissions different from those in the distributed Debian
7214 package, he can use the <prgn>dpkg-statoverride</prgn>
7215 program to instruct <prgn>dpkg</prgn> to use the different
7216 settings every time the file is installed. Thus the
7217 package maintainer should distribute the files with their
7218 normal permissions, and leave it for the system
7219 administrator to make any desired changes. For example, a
7220 daemon which is normally required to be setuid root, but
7221 in certain situations could be used without being setuid,
7222 should be installed setuid in the <tt>.deb</tt>. Then the
7223 local system administrator can change this if they wish.
7224 If there are two standard ways of doing it, the package
7225 maintainer can use <tt>debconf</tt> to find out the
7226 preference, and call <prgn>dpkg-statoverride</prgn> in the
7227 maintainer script if necessary to accommodate the system
7228 administrator's choice.
7232 Given the above, <prgn>dpkg-statoverride</prgn> is
7233 essentially a tool for system administrators and would not
7234 normally be needed in the maintainer scripts. There is
7235 one type of situation, though, where calls to
7236 <prgn>dpkg-statoverride</prgn> would be needed in the
7237 maintainer scripts, and that involves packages which use
7238 dynamically allocated user or group ids. In such a
7239 situation, something like the following idiom can be very
7240 helpful in the package's <prgn>postinst</prgn>, where
7241 <tt>sysuser</tt> is a dynamically allocated id:
7243 for i in /usr/bin/foo /usr/sbin/bar
7245 if ! dpkg-statoverride --list $i >/dev/null
7247 dpkg-statoverride --update --add sysuser root 4755 $i
7251 The corresponding <tt>dpkg-statoverride --remove</tt>
7252 calls can then be made unconditionally when the package is
7260 <chapt id="customized-programs">
7261 <heading>Customized programs</heading>
7263 <sect id="arch-spec">
7264 <heading>Architecture specification strings</heading>
7267 If a program needs to specify an <em>architecture specification
7268 string</em> in some place, the following format should be
7269 used: <var>arch</var>-<var>os</var><footnote>
7270 The following architectures and operating systems are
7271 currently recognised by <prgn>dpkg-architecture</prgn>.
7272 The architecture, <tt><var>arch</var></tt>, is one of
7273 the following: <tt>alpha</tt>, <tt>arm</tt>,
7274 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7275 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7276 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7277 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7278 operating system, <tt><var>os</var></tt>, is one of:
7279 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7280 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7281 reserved for the GNU/Hurd operating system.
7286 Note that we don't want to use
7287 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7288 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7289 since this would make our programs incompatible with other
7290 Linux distributions. We also don't use something like
7291 <tt><var>arch</var>-unknown-linux</tt>, since the
7292 <tt>unknown</tt> does not look very good.
7297 <heading>Daemons</heading>
7300 The configuration files <file>/etc/services</file>,
7301 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7302 by the <prgn>netbase</prgn> package and must not be modified
7307 If a package requires a new entry in one of these files, the
7308 maintainer should get in contact with the
7309 <prgn>netbase</prgn> maintainer, who will add the entries
7310 and release a new version of the <prgn>netbase</prgn>
7315 The configuration file <file>/etc/inetd.conf</file> must not be
7316 modified by the package's scripts except via the
7317 <prgn>update-inetd</prgn> script or the
7318 <file>DebianNet.pm</file> Perl module. See their documentation
7319 for details on how to add entries.
7323 If a package wants to install an example entry into
7324 <file>/etc/inetd.conf</file>, the entry must be preceded with
7325 exactly one hash character (<tt>#</tt>). Such lines are
7326 treated as "commented out by user" by the
7327 <prgn>update-inetd</prgn> script and are not changed or
7328 activated during package updates.
7333 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7337 Some programs need to create pseudo-ttys. This should be done
7338 using Unix98 ptys if the C library supports it. The resulting
7339 program must not be installed setuid root, unless that
7340 is required for other functionality.
7344 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7345 <file>/var/log/lastlog</file> must be installed writeable by
7346 group <tt>utmp</tt>. Programs which need to modify those
7347 files must be installed setgid <tt>utmp</tt>.
7352 <heading>Editors and pagers</heading>
7355 Some programs have the ability to launch an editor or pager
7356 program to edit or display a text document. Since there are
7357 lots of different editors and pagers available in the Debian
7358 distribution, the system administrator and each user should
7359 have the possibility to choose his/her preferred editor and
7364 In addition, every program should choose a good default
7365 editor/pager if none is selected by the user or system
7370 Thus, every program that launches an editor or pager must
7371 use the EDITOR or PAGER environment variable to determine
7372 the editor or pager the user wishes to use. If these
7373 variables are not set, the programs <file>/usr/bin/editor</file>
7374 and <file>/usr/bin/pager</file> should be used, respectively.
7378 These two files are managed through the <prgn>dpkg</prgn>
7379 "alternatives" mechanism. Thus every package providing an
7380 editor or pager must call the
7381 <prgn>update-alternatives</prgn> script to register these
7386 If it is very hard to adapt a program to make use of the
7387 EDITOR or PAGER variables, that program may be configured to
7388 use <file>/usr/bin/sensible-editor</file> and
7389 <file>/usr/bin/sensible-pager</file> as the editor or pager
7390 program respectively. These are two scripts provided in the
7391 Debian base system that check the EDITOR and PAGER variables
7392 and launch the appropriate program, and fall back to
7393 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7394 variable is not set.
7398 A program may also use the VISUAL environment variable to
7399 determine the user's choice of editor. If it exists, it
7400 should take precedence over EDITOR. This is in fact what
7401 <file>/usr/bin/sensible-editor</file> does.
7405 It is not required for a package to depend on
7406 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7407 package to provide such virtual packages.<footnote>
7408 The Debian base system already provides an editor and a
7414 <sect id="web-appl">
7415 <heading>Web servers and applications</heading>
7418 This section describes the locations and URLs that should
7419 be used by all web servers and web applications in the
7426 Cgi-bin executable files are installed in the
7428 <example compact="compact">
7429 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7431 and should be referred to as
7432 <example compact="compact">
7433 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7438 <p>Access to HTML documents</p>
7441 HTML documents for a package are stored in
7442 <file>/usr/share/doc/<var>package</var></file>
7443 and can be referred to as
7444 <example compact="compact">
7445 http://localhost/doc/<var>package</var>/<var>filename</var>
7450 The web server should restrict access to the document
7451 tree so that only clients on the same host can read
7452 the documents. If the web server does not support such
7453 access controls, then it should not provide access at
7454 all, or ask about providing access during installation.
7459 <p>Web Document Root</p>
7462 Web Applications should try to avoid storing files in
7463 the Web Document Root. Instead they should use the
7464 /usr/share/doc/<var>package</var> directory for
7465 documents and register the Web Application via the
7466 <package>doc-base</package> package. If access to the
7467 web document root is unavoidable then use
7468 <example compact="compact">
7471 as the Document Root. This might be just a symbolic
7472 link to the location where the system administrator
7473 has put the real document root.
7481 <sect id="mail-transport-agents">
7482 <heading>Mail transport, delivery and user agents</heading>
7485 Debian packages which process electronic mail, whether mail
7486 user agents (MUAs) or mail transport agents (MTAs), must
7487 ensure that they are compatible with the configuration
7488 decisions below. Failure to do this may result in lost
7489 mail, broken <tt>From:</tt> lines, and other serious brain
7494 The mail spool is <file>/var/mail</file> and the interface to
7495 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7496 the FHS). On older systems, the mail spool may be
7497 physically located in <file>/var/spool/mail</file>, but all
7498 access to the mail spool should be via the
7499 <file>/var/mail</file> symlink. The mail spool is part of the
7500 base system and not part of the MTA package.
7504 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7505 programs (such as IMAP daemons) must lock the mailbox in an
7506 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7507 be combined with dot locking. To avoid deadlocks, a program
7508 should use <tt>fcntl()</tt> first and dot locking after
7509 this, or alternatively implement the two locking methods in
7510 a non blocking way<footnote>
7511 If it is not possible to establish both locks, the
7512 system shouldn't wait for the second lock to be
7513 established, but remove the first lock, wait a (random)
7514 time, and start over locking again.
7515 </footnote>. Using the functions <tt>maillock</tt> and
7516 <tt>mailunlock</tt> provided by the
7517 <tt>liblockfile*</tt><footnote>
7518 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7519 to use these functions.
7520 </footnote> packages is the recommended way to realize this.
7524 Mailboxes are generally mode 660
7525 <tt><var>user</var>.mail</tt> unless the system
7526 administrator has chosen otherwise. A MUA may remove a
7527 mailbox (unless it has nonstandard permissions) in which
7528 case the MTA or another MUA must recreate it if needed.
7529 Mailboxes must be writable by group mail.
7533 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7534 be setgid mail to do the locking mentioned above (and
7535 must obviously avoid accessing other users' mailboxes
7536 using this privilege).</p>
7539 <file>/etc/aliases</file> is the source file for the system mail
7540 aliases (e.g., postmaster, usenet, etc.), it is the one
7541 which the sysadmin and <prgn>postinst</prgn> scripts may
7542 edit. After <file>/etc/aliases</file> is edited the program or
7543 human editing it must call <prgn>newaliases</prgn>. All MTA
7544 packages must come with a <prgn>newaliases</prgn> program,
7545 even if it does nothing, but older MTA packages did not do
7546 this so programs should not fail if <prgn>newaliases</prgn>
7547 cannot be found. Note that because of this, all MTA
7548 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7549 <tt>Replaces: mail-transport-agent</tt> control file
7554 The convention of writing <tt>forward to
7555 <var>address</var></tt> in the mailbox itself is not
7556 supported. Use a <tt>.forward</tt> file instead.</p>
7559 The <prgn>rmail</prgn> program used by UUCP
7560 for incoming mail should be <file>/usr/sbin/rmail</file>.
7561 Likewise, <prgn>rsmtp</prgn>, for receiving
7562 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7566 If your package needs to know what hostname to use on (for
7567 example) outgoing news and mail messages which are generated
7568 locally, you should use the file <file>/etc/mailname</file>. It
7569 will contain the portion after the username and <tt>@</tt>
7570 (at) sign for email addresses of users on the machine
7571 (followed by a newline).
7575 Such package should check for the existence of this file
7576 when it is being configured. If it exists, it should be
7577 used without comment, although an MTA's configuration script
7578 may wish to prompt the user even if it finds that this file
7579 exists. If the file does not exist, the package should
7580 prompt the user for the value (preferably using
7581 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7582 as well as using it in the package's configuration. The
7583 prompt should make it clear that the name will not just be
7584 used by that package. For example, in this situation the
7585 <tt>inn</tt> package could say something like:
7586 <example compact="compact">
7587 Please enter the "mail name" of your system. This is the
7588 hostname portion of the address to be shown on outgoing
7589 news and mail messages. The default is
7590 <var>syshostname</var>, your system's host name. Mail
7591 name ["<var>syshostname</var>"]:
7593 where <var>syshostname</var> is the output of <tt>hostname
7599 <heading>News system configuration</heading>
7602 All the configuration files related to the NNTP (news)
7603 servers and clients should be located under
7604 <file>/etc/news</file>.</p>
7607 There are some configuration issues that apply to a number
7608 of news clients and server packages on the machine. These
7612 <tag><file>/etc/news/organization</file></tag>
7614 A string which should appear as the
7615 organization header for all messages posted
7616 by NNTP clients on the machine
7619 <tag><file>/etc/news/server</file></tag>
7621 Contains the FQDN of the upstream NNTP
7622 server, or localhost if the local machine is
7627 Other global files may be added as required for cross-package news
7634 <heading>Programs for the X Window System</heading>
7637 <heading>Providing X support and package priorities</heading>
7640 Programs that can be configured with support for the X
7641 Window System must be configured to do so and must declare
7642 any package dependencies necessary to satisfy their
7643 runtime requirements when using the X Window System. If
7644 such a package is of higher priority than the X packages
7645 on which it depends, it is required that either the
7646 X-specific components be split into a separate package, or
7647 that an alternative version of the package, which includes
7648 X support, be provided, or that the package's priority be
7654 <heading>Packages providing an X server</heading>
7657 Packages that provide an X server that, directly or
7658 indirectly, communicates with real input and display
7659 hardware should declare in their control data that they
7660 provide the virtual package <tt>xserver</tt>.<footnote>
7661 This implements current practice, and provides an
7662 actual policy for usage of the <tt>xserver</tt>
7663 virtual package which appears in the virtual packages
7664 list. In a nutshell, X servers that interface
7665 directly with the display and input hardware or via
7666 another subsystem (e.g., GGI) should provide
7667 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7668 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7674 <heading>Packages providing a terminal emulator</heading>
7677 Packages that provide a terminal emulator for the X Window
7678 System which meet the criteria listed below should declare
7679 in their control data that they provide the virtual
7680 package <tt>x-terminal-emulator</tt>. They should also
7681 register themselves as an alternative for
7682 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7687 To be an <tt>x-terminal-emulator</tt>, a program must:
7688 <list compact="compact">
7690 Be able to emulate a DEC VT100 terminal, or a
7691 compatible terminal.
7695 Support the command-line option <tt>-e
7696 <var>command</var></tt>, which creates a new
7697 terminal window<footnote>
7698 "New terminal window" does not necessarily mean
7699 a new top-level X window directly parented by
7700 the window manager; it could, if the terminal
7701 emulator application were so coded, be a new
7702 "view" in a multiple-document interface (MDI).
7704 and runs the specified <var>command</var>,
7705 interpreting the entirity of the rest of the command
7706 line as a command to pass straight to exec, in the
7707 manner that <tt>xterm</tt> does.
7711 Support the command-line option <tt>-T
7712 <var>title</var></tt>, which creates a new terminal
7713 window with the window title <var>title</var>.
7720 <heading>Packages providing a window manager</heading>
7723 Packages that provide a window manager should declare in
7724 their control data that they provide the virtual package
7725 <tt>x-window-manager</tt>. They should also register
7726 themselves as an alternative for
7727 <file>/usr/bin/x-window-manager</file>, with a priority
7728 calculated as follows:
7729 <list compact="compact">
7731 Start with a priority of 20.
7735 If the window manager supports the Debian menu
7736 system, add 20 points if this support is available
7737 in the package's default configuration (i.e., no
7738 configuration files belonging to the system or user
7739 have to be edited to activate the feature); if
7740 configuration files must be modified, add only 10
7746 If the window manager complies with <url
7747 id="http://www.freedesktop.org/Standards/wm-spec"
7748 name="The Window Manager Specification Project">,
7749 written by the <url id="http://www.freedesktop.org/"
7750 name="Free Desktop Group">, add 40 points.
7754 If the window manager permits the X session to be
7755 restarted using a <em>different</em> window manager
7756 (without killing the X server) in its default
7757 configuration, add 10 points; otherwise add none.
7764 <heading>Packages providing fonts</heading>
7767 Packages that provide fonts for the X Window
7769 For the purposes of Debian Policy, a "font for the X
7770 Window System" is one which is accessed via X protocol
7771 requests. Fonts for the Linux console, for PostScript
7772 renderers, or any other purpose, do not fit this
7773 definition. Any tool which makes such fonts available
7774 to the X Window System, however, must abide by this
7777 must do a number of things to ensure that they are both
7778 available without modification of the X or font server
7779 configuration, and that they do not corrupt files used by
7780 other font packages to register information about
7784 Fonts of any type supported by the X Window System
7785 must be in a separate binary package from any
7786 executables, libraries, or documentation (except
7787 that specific to the fonts shipped, such as their
7788 license information). If one or more of the fonts
7789 so packaged are necessary for proper operation of
7790 the package with which they are associated the font
7791 package may be Recommended; if the fonts merely
7792 provide an enhancement, a Suggests relationship may
7793 be used. Packages must not Depend on font
7795 This is because the X server may retrieve fonts
7796 from the local filesystem or over the network
7797 from an X font server; the Debian package system
7798 is empowered to deal only with the local
7804 BDF fonts must be converted to PCF fonts with the
7805 <prgn>bdftopcf</prgn> utility (available in the
7806 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7807 placed in a directory that corresponds to their
7809 <list compact="compact">
7811 100 dpi fonts must be placed in
7812 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7816 75 dpi fonts must be placed in
7817 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7821 Character-cell fonts, cursor fonts, and other
7822 low-resolution fonts must be placed in
7823 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7829 Speedo fonts must be placed in
7830 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7834 Type 1 fonts must be placed in
7835 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7836 metric files are available, they must be placed here
7841 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7842 other than those listed above must be neither
7843 created nor used. (The <file>PEX</file>, <file>CID</file>,
7844 and <file>cyrillic</file> directories are excepted for
7845 historical reasons, but installation of files into
7846 these directories remains discouraged.)
7850 Font packages may, instead of placing files directly
7851 in the X font directories listed above, provide
7852 symbolic links in that font directory pointing to
7853 the files' actual location in the filesystem. Such
7854 a location must comply with the FHS.
7858 Font packages should not contain both 75dpi and
7859 100dpi versions of a font. If both are available,
7860 they should be provided in separate binary packages
7861 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7862 the names of the packages containing the
7863 corresponding fonts.
7867 Fonts destined for the <file>misc</file> subdirectory
7868 should not be included in the same package as 75dpi
7869 or 100dpi fonts; instead, they should be provided in
7870 a separate package with <tt>-misc</tt> appended to
7875 Font packages must not provide the files
7876 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7877 <file>fonts.scale</file> in a font directory:
7880 <file>fonts.dir</file> files must not be provided at all.
7884 <file>fonts.alias</file> and <file>fonts.scale</file>
7885 files, if needed, should be provided in the
7887 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7888 where <var>fontdir</var> is the name of the
7890 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7891 package's corresponding fonts are stored
7892 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7893 <var>package</var> is the name of the package
7894 that provides these fonts, and
7895 <var>extension</var> is either <tt>scale</tt>
7896 or <tt>alias</tt>, whichever corresponds to
7903 Font packages must declare a dependency on
7904 <tt>xutils (>> 4.0.3)</tt> in their control
7909 Font packages that provide one or more
7910 <file>fonts.scale</file> files as described above must
7911 invoke <prgn>update-fonts-scale</prgn> on each
7912 directory into which they installed fonts
7913 <em>before</em> invoking
7914 <prgn>update-fonts-dir</prgn> on that directory.
7915 This invocation must occur in both the
7916 <prgn>postinst</prgn> (for all arguments) and
7917 <prgn>postrm</prgn> (for all arguments except
7918 <tt>upgrade</tt>) scripts.
7922 Font packages that provide one or more
7923 <file>fonts.alias</file> files as described above must
7924 invoke <prgn>update-fonts-alias</prgn> on each
7925 directory into which they installed fonts. This
7926 invocation must occur in both the
7927 <prgn>postinst</prgn> (for all arguments) and
7928 <prgn>postrm</prgn> (for all arguments except
7929 <tt>upgrade</tt>) scripts.
7933 Font packages must invoke
7934 <prgn>update-fonts-dir</prgn> on each directory into
7935 which they installed fonts. This invocation must
7936 occur in both the <prgn>postinst</prgn> (for all
7937 arguments) and <prgn>postrm</prgn> (for all
7938 arguments except <tt>upgrade</tt>) scripts.
7942 Font packages must not provide alias names for the
7943 fonts they include which collide with alias names
7944 already in use by fonts already packaged.
7948 Font packages must not provide fonts with the same
7949 XLFD registry name as another font already packaged.
7956 <heading>Application defaults files</heading>
7959 Application defaults files must be installed in the
7960 directory <file>/etc/X11/app-defaults/</file> (use of a
7961 localized subdirectory of <file>/etc/X11/</file> as described
7962 in the <em>X Toolkit Intrinsics - C Language
7963 Interface</em> manual is also permitted). They must be
7964 registered as <tt>conffile</tt>s or handled as
7965 configuration files. Packages must not provide the
7966 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7970 Customization of programs' X resources may also be
7971 supported with the provision of a file with the same name
7972 as that of the package placed in the
7973 <file>/etc/X11/Xresources/</file> directory, which must
7974 registered as a <tt>conffile</tt> or handled as a
7975 configuration file.<footnote>
7976 Note that this mechanism is not the same as using
7977 app-defaults; app-defaults are tied to the client
7978 binary on the local filesystem, whereas X resources
7979 are stored in the X server and affect all connecting
7982 <em>Important:</em> packages that install files into the
7983 <file>/etc/X11/Xresources/</file> directory must conflict with
7984 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7985 it is possible for the installing package to destroy a
7986 previously-existing <file>/etc/X11/Xresources</file> file
7987 which had been customized by the system administrator.
7992 <heading>Installation directory issues</heading>
7995 Packages using the X Window System should not be
7996 configured to install files under the <file>/usr/X11R6/</file>
7997 directory unless they use <prgn>imake</prgn>. The
7998 <file>/usr/X11R6/</file> directory hierarchy should be
7999 regarded as deprecated for all packages except the X
8000 Window System itself, and those which use the
8001 <prgn>imake</prgn> program it provides, in which case the
8002 packages may transition out of the <file>/usr/X11R6/</file>
8003 directory at the maintainer's discretion.<footnote>
8004 <prgn>Imake</prgn>-using programs are exempt because,
8005 as long as they are written correctly, the pathnames
8006 they use to locate resources and install themselves
8007 are derived wholly from the X Window System
8008 configuration. Thus, in the event that the X Window
8009 System moves to <file>/usr/X11R7/</file>,
8010 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
8011 that is required for these programs is a recompile
8012 against the corresponding X Window System library
8013 development packages.
8018 Programs that use GNU <prgn>autoconf</prgn> and
8019 <prgn>automake</prgn> are usually easily configured at
8020 compile time to use <file>/usr/</file> instead of
8021 <file>/usr/X11R6/</file>, and this should be done whenever
8022 possible. Configuration files for window managers and
8023 display managers should be placed in a subdirectory of
8024 <file>/etc/X11/</file> corresponding to the package name due
8025 to these programs' tight integration with the mechanisms
8026 of the X Window System. Application-level programs should
8027 use the <file>/etc/</file> directory unless otherwise mandated
8032 The installation of files into subdirectories
8033 of <file>/usr/X11R6/include/X11/</file> and
8034 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8035 package maintainers should determine if subdirectories of
8036 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8037 instead. (The use of symbolic links from the
8038 <file>X11R6</file> directories to other FHS-compliant
8039 locations is encouraged if the program is not easily
8040 configured to look elsewhere for its files.)
8044 Packages must not provide or install files into the directories
8045 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8046 <file>/usr/lib/X11/</file>. Files within a package should,
8047 however, make reference to these directories, rather than
8048 their <tt>X11R6</tt>-named counterparts
8049 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8050 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8051 referred to have not been moved to other FHS-compliant
8057 <heading>The OSF/Motif and OpenMotif libraries</heading>
8060 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8061 OpenMotif libraries</em><footnote>
8062 OSF/Motif and OpenMotif are collectively referred to as
8063 "Motif" in this policy document.
8065 should be compiled against and tested with LessTif (a free
8066 re-implementation of Motif) instead. If the maintainer
8067 judges that the program or programs do not work
8068 sufficiently well with LessTif to be distributed and
8069 supported, but do so when compiled against Motif, then two
8070 versions of the package should be created; one linked
8071 statically against Motif and with <tt>-smotif</tt>
8072 appended to the package name, and one linked dynamically
8073 against Motif and with <tt>-dmotif</tt> appended to the
8078 Both Motif-linked versions are dependent
8079 upon non-DFSG-compliant software and thus cannot be
8080 uploaded to the <em>main</em> distribution; if the
8081 software is itself DFSG-compliant it may be uploaded to
8082 the <em>contrib</em> distribution. While known existing
8083 versions of Motif permit unlimited redistribution of
8084 binaries linked against the library (whether statically or
8085 dynamically), it is the package maintainer's
8086 responsibility to determine whether this is permitted by
8087 the license of the copy of Motif in his or her possession.
8093 <heading>Perl programs and modules</heading>
8096 Perl programs and modules should follow the current Perl policy.
8100 The Perl policy can be found in the <tt>perl-policy</tt>
8101 files in the <tt>debian-policy</tt> package.
8102 It is also available from the Debian web mirrors at
8103 <tt><url name="/doc/packaging-manuals/perl-policy/"
8104 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8109 <heading>Emacs lisp programs</heading>
8112 Please refer to the "Debian Emacs Policy" for details of how to
8113 package emacs lisp programs.
8117 The Emacs policy is available in
8118 <file>debian-emacs-policy.gz</file> of the
8119 <package>emacsen-common</package> package.
8120 It is also available from the Debian web mirrors at
8121 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8122 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8127 <heading>Games</heading>
8130 The permissions on <file>/var/games</file> are mode 755, owner
8131 <tt>root</tt> and group <tt>root</tt>.
8135 Each game decides on its own security policy.</p>
8138 Games which require protected, privileged access to
8139 high-score files, savegames, etc., may be made
8140 set-<em>group</em>-id (mode 2755) and owned by
8141 <tt>root.games</tt>, and use files and directories with
8142 appropriate permissions (770 <tt>root.games</tt>, for
8143 example). They must not be made
8144 set-<em>user</em>-id, as this causes security problems. (If
8145 an attacker can subvert any set-user-id game they can
8146 overwrite the executable of any other, causing other players
8147 of these games to run a Trojan horse program. With a
8148 set-group-id game the attacker only gets access to less
8149 important game data, and if they can get at the other
8150 players' accounts at all it will take considerably more
8154 Some packages, for example some fortune cookie programs, are
8155 configured by the upstream authors to install with their
8156 data files or other static information made unreadable so
8157 that they can only be accessed through set-id programs
8158 provided. You should not do this in a Debian package: anyone can
8159 download the <file>.deb</file> file and read the data from it,
8160 so there is no point making the files unreadable. Not
8161 making the files unreadable also means that you don't have
8162 to make so many programs set-id, which reduces the risk of a
8166 As described in the FHS, binaries of games should be
8167 installed in the directory <file>/usr/games</file>. This also
8168 applies to games that use the X Window System. Manual pages
8169 for games (X and non-X games) should be installed in
8170 <file>/usr/share/man/man6</file>.</p>
8176 <heading>Documentation</heading>
8179 <heading>Manual pages</heading>
8182 You should install manual pages in <prgn>nroff</prgn> source
8183 form, in appropriate places under <file>/usr/share/man</file>.
8184 You should only use sections 1 to 9 (see the FHS for more
8185 details). You must not install a preformatted "cat page".
8189 Each program, utility, and function should have an
8190 associated manual page included in the same package. It is
8191 suggested that all configuration files also have a manual
8192 page included as well. Manual pages for protocols and other
8193 auxiliary things are optional.
8197 If no manual page is available, this is considered as a bug
8198 and should be reported to the Debian Bug Tracking System (the
8199 maintainer of the package is allowed to write this bug report
8200 themselves, if they so desire). Do not close the bug report
8201 until a proper man page is available.<footnote>
8202 It is not very hard to write a man page. See the
8203 <url id="http://www.schweikhardt.net/man_page_howto.html"
8204 name="Man-Page-HOWTO">,
8205 <manref name="man" section="7">, the examples
8206 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8207 the helper programs <prgn>help2man</prgn>, or the
8208 directory <file>/usr/share/doc/man-db/examples</file>.
8213 You may forward a complaint about a missing man page to the
8214 upstream authors, and mark the bug as forwarded in the
8215 Debian bug tracking system. Even though the GNU Project do
8216 not in general consider the lack of a man page to be a bug,
8217 we do; if they tell you that they don't consider it a bug
8218 you should leave the bug in our bug tracking system open
8223 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8227 If one man page needs to be accessible via several names it
8228 is better to use a symbolic link than the <file>.so</file>
8229 feature, but there is no need to fiddle with the relevant
8230 parts of the upstream source to change from <file>.so</file> to
8231 symlinks: don't do it unless it's easy. You should not
8232 create hard links in the manual page directories, nor put
8233 absolute filenames in <file>.so</file> directives. The filename
8234 in a <file>.so</file> in a man page should be relative to the
8235 base of the man page tree (usually
8236 <file>/usr/share/man</file>). If you do not create any links
8237 (whether symlinks, hard links, or <tt>.so</tt> directives)
8238 in the filesystem to the alternate names of the man page,
8239 then you should not rely on <prgn>man</prgn> finding your
8240 man page under those names based solely on the information in
8241 the man page's header.<footnote>
8242 Supporting this in <prgn>man</prgn> often requires
8243 unreasonable processing time to find a manual page or to
8244 report that none exists, and moves knowledge into man's
8245 database that would be better left in the filesystem.
8246 This support is therefore deprecated and will cease to
8247 be present in the future.
8253 <heading>Info documents</heading>
8256 Info documents should be installed in <file>/usr/share/info</file>.
8257 They should be compressed with <tt>gzip -9</tt>.
8261 Your package should call <prgn>install-info</prgn> to update
8262 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8263 script when called with a <tt>configure</tt> argument, for
8265 <example compact="compact">
8266 install-info --quiet --section Development Development \
8267 /usr/share/info/foobar.info
8271 It is a good idea to specify a section for the location of
8272 your program; this is done with the <tt>--section</tt>
8273 switch. To determine which section to use, you should look
8274 at <file>/usr/share/info/dir</file> on your system and choose the most
8275 relevant (or create a new section if none of the current
8276 sections are relevant). Note that the <tt>--section</tt>
8277 flag takes two arguments; the first is a regular expression
8278 to match (case-insensitively) against an existing section,
8279 the second is used when creating a new one.</p>
8282 You should remove the entries in the <prgn>prerm</prgn>
8283 script when called with a <tt>remove</tt> argument:
8284 <example compact="compact">
8285 install-info --quiet --remove /usr/share/info/foobar.info
8289 If <prgn>install-info</prgn> cannot find a description entry
8290 in the Info file you must supply one. See <manref
8291 name="install-info" section="8"> for details.</p>
8295 <heading>Additional documentation</heading>
8298 Any additional documentation that comes with the package may
8299 be installed at the discretion of the package maintainer.
8300 Text documentation should be installed in the directory
8301 <file>/usr/share/doc/<var>package</var></file>, where
8302 <var>package</var> is the name of the package, and
8303 compressed with <tt>gzip -9</tt> unless it is small.
8307 If a package comes with large amounts of documentation which
8308 many users of the package will not require you should create
8309 a separate binary package to contain it, so that it does not
8310 take up disk space on the machines of users who do not need
8311 or want it installed.</p>
8314 It is often a good idea to put text information files
8315 (<file>README</file>s, changelogs, and so forth) that come with
8316 the source package in <file>/usr/share/doc/<var>package</var></file>
8317 in the binary package. However, you don't need to install
8318 the instructions for building and installing the package, of
8322 Packages must not require the existence of any files in
8323 <file>/usr/share/doc/</file> in order to function
8325 The system administrator should be able to
8326 delete files in <file>/usr/share/doc/</file> without causing
8327 any programs to break.
8329 Any files that are referenced by programs but are also
8330 useful as standalone documentation should be installed under
8331 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8332 <file>/usr/share/doc/<var>package</var></file>.
8336 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8337 link to another directory in <file>/usr/share/doc</file> only if
8338 the two packages both come from the same source and the
8339 first package Depends on the second.
8343 Former Debian releases placed all additional documentation
8344 in <file>/usr/doc/<var>package</var></file>. This has been
8345 changed to <file>/usr/share/doc/<var>package</var></file>,
8346 and packages must not put documentation in the directory
8347 <file>/usr/doc/<var>package</var></file>. <footnote>
8348 At this phase of the transition, we no longer require a
8349 symbolic link in <file>/usr/doc/</file>. At a later point,
8350 policy shall change to make the symbolic links a bug.
8356 <heading>Preferred documentation formats</heading>
8359 The unification of Debian documentation is being carried out
8363 If your package comes with extensive documentation in a
8364 markup format that can be converted to various other formats
8365 you should if possible ship HTML versions in a binary
8366 package, in the directory
8367 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8368 its subdirectories.<footnote>
8369 The rationale: The important thing here is that HTML
8370 docs should be available in <em>some</em> package, not
8371 necessarily in the main binary package.
8376 Other formats such as PostScript may be provided at the
8377 package maintainer's discretion.
8381 <sect id="copyrightfile">
8382 <heading>Copyright information</heading>
8385 Every package must be accompanied by a verbatim copy of its
8386 copyright and distribution license in the file
8387 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8388 file must neither be compressed nor be a symbolic link.
8392 In addition, the copyright file must say where the upstream
8393 sources (if any) were obtained. It should name the original
8394 authors of the package and the Debian maintainer(s) who were
8395 involved with its creation.</p>
8398 A copy of the file which will be installed in
8399 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8400 be in <file>debian/copyright</file> in the source package.
8404 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8405 link to another directory in <file>/usr/share/doc</file> only if
8406 the two packages both come from the same source and the
8407 first package Depends on the second. These rules are
8408 important because copyrights must be extractable by
8413 Packages distributed under the UCB BSD license, the Artistic
8414 license, the GNU GPL, and the GNU LGPL should refer to the
8415 files <file>/usr/share/common-licenses/BSD</file>,
8416 <file>/usr/share/common-licenses/Artistic</file>,
8417 <file>/usr/share/common-licenses/GPL</file>, and
8418 <file>/usr/share/common-licenses/LGPL</file> respectively,
8419 rather than quoting them in the copyright file.
8423 You should not use the copyright file as a general <file>README</file>
8424 file. If your package has such a file it should be
8425 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8426 <file>README.Debian</file> or some other appropriate place.</p>
8430 <heading>Examples</heading>
8433 Any examples (configurations, source files, whatever),
8434 should be installed in a directory
8435 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8436 files should not be referenced by any program: they're there
8437 for the benefit of the system administrator and users as
8438 documentation only. Architecture-specific example files
8439 should be installed in a directory
8440 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8442 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8443 latter directory itself may be a symbolic link to the
8448 If the purpose of a package is to provide examples, then the
8449 example files may be installed into
8450 <file>/usr/share/doc/<var>package</var></file>.
8454 <sect id="changelogs">
8455 <heading>Changelog files</heading>
8458 Packages that are not Debian-native must contain a
8459 compressed copy of the <file>debian/changelog</file> file from
8460 the Debian source tree in
8461 <file>/usr/share/doc/<var>package</var></file> with the name
8462 <file>changelog.Debian.gz</file>.
8466 If an upstream changelog is available, it should be accessible as
8467 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8468 plain text. If the upstream changelog is distributed in
8469 HTML, it should be made available in that form as
8470 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8471 and a plain text <file>changelog.gz</file> should be generated
8472 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8473 the upstream changelog files do not already conform to this
8474 naming convention, then this may be achieved either by
8475 renaming the files, or by adding a symbolic link, at the
8476 maintainer's discretion.<footnote>
8477 Rationale: People should not have to look in places for
8478 upstream changelogs merely because they are given
8479 different names or are distributed in HTML format.
8484 All of these files should be installed compressed using
8485 <tt>gzip -9</tt>, as they will become large with time even
8486 if they start out small.
8490 If the package has only one changelog which is used both as
8491 the Debian changelog and the upstream one because there is
8492 no separate upstream maintainer then that changelog should
8493 usually be installed as
8494 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8495 there is a separate upstream maintainer, but no upstream
8496 changelog, then the Debian changelog should still be called
8497 <file>changelog.Debian.gz</file>.
8501 For details about the format and contents of the Debian
8502 changelog file, please see <ref id="dpkgchangelog">.
8507 <appendix id="pkg-scope">
8508 <heading>Introduction and scope of these appendices</heading>
8511 These appendices are taken essentially verbatim from the
8512 now-deprecated Packaging Manual, version 3.2.1.0. They are
8513 the chapters which are likely to be of use to package
8514 maintainers and which have not already been included in the
8515 policy document itself. Most of these sections are very likely
8516 not relevant to policy; they should be treated as
8517 documentation for the packaging system. Please note that these
8518 appendices are included for convenience, and for historical
8519 reasons: they used to be part of policy package, and they have
8520 not yet been incorporated into dpkg documentation. However,
8521 they still have value, and hence they are presented here.
8525 They have not yet been checked to ensure that they are
8526 compatible with the contents of policy, and if there are any
8527 contradictions, the version in the main policy document takes
8528 precedence. The remaining chapters of the old Packaging
8529 Manual have also not been read in detail to ensure that there
8530 are not parts which have been left out. Both of these will be
8535 Certain parts of the Packaging manual were integrated into the
8536 Policy Manual proper, and removed from the appendices. Links
8537 have been placed from the old locations to the new ones.
8541 <prgn>dpkg</prgn> is a suite of programs for creating binary
8542 package files and installing and removing them on Unix
8544 <prgn>dpkg</prgn> is targetted primarily at Debian
8545 GNU/Linux, but may work on or be ported to other
8551 The binary packages are designed for the management of
8552 installed executable programs (usually compiled binaries) and
8553 their associated data, though source code examples and
8554 documentation are provided as part of some packages.</p>
8557 This manual describes the technical aspects of creating Debian
8558 binary packages (<file>.deb</file> files). It documents the
8559 behaviour of the package management programs
8560 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8561 they interact with packages.</p>
8564 It also documents the interaction between
8565 <prgn>dselect</prgn>'s core and the access method scripts it
8566 uses to actually install the selected packages, and describes
8567 how to create a new access method.</p>
8570 This manual does not go into detail about the options and
8571 usage of the package building and installation tools. It
8572 should therefore be read in conjuction with those programs'
8577 The utility programs which are provided with <prgn>dpkg</prgn>
8578 for managing various system configuration and similar issues,
8579 such as <prgn>update-rc.d</prgn> and
8580 <prgn>install-info</prgn>, are not described in detail here -
8581 please see their man pages.
8585 It is assumed that the reader is reasonably familiar with the
8586 <prgn>dpkg</prgn> System Administrators' manual.
8587 Unfortunately this manual does not yet exist.
8591 The Debian version of the FSF's GNU hello program is provided
8592 as an example for people wishing to create Debian
8593 packages. The Debian <prgn>debmake</prgn> package is
8594 recommended as a very helpful tool in creating and maintaining
8595 Debian packages. However, while the tools and examples are
8596 helpful, they do not replace the need to read and follow the
8597 Policy and Programmer's Manual.</p>
8600 <appendix id="pkg-binarypkg">
8601 <heading>Binary packages (from old Packaging Manual)</heading>
8604 The binary package has two main sections. The first part
8605 consists of various control information files and scripts used
8606 by <prgn>dpkg</prgn> when installing and removing. See <ref
8607 id="pkg-controlarea">.
8611 The second part is an archive containing the files and
8612 directories to be installed.
8616 In the future binary packages may also contain other
8617 components, such as checksums and digital signatures. The
8618 format for the archive is described in full in the
8619 <file>deb(5)</file> man page.
8623 <sect id="pkg-bincreating"><heading>Creating package files -
8624 <prgn>dpkg-deb</prgn>
8628 All manipulation of binary package files is done by
8629 <prgn>dpkg-deb</prgn>; it's the only program that has
8630 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8631 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8632 will spot that the options requested are appropriate to
8633 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8638 In order to create a binary package you must make a
8639 directory tree which contains all the files and directories
8640 you want to have in the filesystem data part of the package.
8641 In Debian-format source packages this directory is usually
8642 <file>debian/tmp</file>, relative to the top of the package's
8647 They should have the locations (relative to the root of the
8648 directory tree you're constructing) ownerships and
8649 permissions which you want them to have on the system when
8654 With current versions of <prgn>dpkg</prgn> the uid/username
8655 and gid/groupname mappings for the users and groups being
8656 used should be the same on the system where the package is
8657 built and the one where it is installed.
8661 You need to add one special directory to the root of the
8662 miniature filesystem tree you're creating:
8663 <prgn>DEBIAN</prgn>. It should contain the control
8664 information files, notably the binary package control file
8665 (see <ref id="pkg-controlfile">).
8669 The <prgn>DEBIAN</prgn> directory will not appear in the
8670 filesystem archive of the package, and so won't be installed
8671 by <prgn>dpkg</prgn> when the package is installed.
8675 When you've prepared the package, you should invoke:
8677 dpkg --build <var>directory</var>
8682 This will build the package in
8683 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8684 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8685 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8690 See the man page <manref name="dpkg-deb" section="8"> for details of how
8691 to examine the contents of this newly-created file. You may find the
8692 output of following commands enlightening:
8694 dpkg-deb --info <var>filename</var>.deb
8695 dpkg-deb --contents <var>filename</var>.deb
8696 dpkg --contents <var>filename</var>.deb
8698 To view the copyright file for a package you could use this command:
8700 dpkg --fsys-tarfile <var>filename</var>.deb | tar xO ./usr/share/doc/\*/copyright | pager
8705 <sect id="pkg-controlarea">
8706 <heading>Package control information files</heading>
8709 The control information portion of a binary package is a
8710 collection of files with names known to <prgn>dpkg</prgn>.
8711 It will treat the contents of these files specially - some
8712 of them contain information used by <prgn>dpkg</prgn> when
8713 installing or removing the package; others are scripts which
8714 the package maintainer wants <prgn>dpkg</prgn> to run.
8718 It is possible to put other files in the package control
8719 area, but this is not generally a good idea (though they
8720 will largely be ignored).
8724 Here is a brief list of the control info files supported by
8725 <prgn>dpkg</prgn> and a summary of what they're used for.
8730 <tag><tt>control</tt>
8733 This is the key description file used by
8734 <prgn>dpkg</prgn>. It specifies the package's name
8735 and version, gives its description for the user,
8736 states its relationships with other packages, and so
8737 forth. See <ref id="sourcecontrolfiles"> and
8738 <ref id="binarycontrolfiles">.
8742 It is usually generated automatically from information
8743 in the source package by the
8744 <prgn>dpkg-gencontrol</prgn> program, and with
8745 assistance from <prgn>dpkg-shlibdeps</prgn>.
8746 See <ref id="pkg-sourcetools">.
8750 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8755 These are exectuable files (usually scripts) which
8756 <prgn>dpkg</prgn> runs during installation, upgrade
8757 and removal of packages. They allow the package to
8758 deal with matters which are particular to that package
8759 or require more complicated processing than that
8760 provided by <prgn>dpkg</prgn>. Details of when and
8761 how they are called are in <ref id="maintainerscripts">.
8765 It is very important to make these scripts idempotent.
8766 See <ref id="idempotency">.
8770 The maintainer scripts are guaranteed to run with a
8771 controlling terminal and can interact with the user.
8772 See <ref id="controllingterminal">.
8776 <tag><tt>conffiles</tt>
8779 This file contains a list of configuration files which
8780 are to be handled automatically by <prgn>dpkg</prgn>
8781 (see <ref id="pkg-conffiles">). Note that not necessarily
8782 every configuration file should be listed here.
8785 <tag><tt>shlibs</tt>
8788 This file contains a list of the shared libraries
8789 supplied by the package, with dependency details for
8790 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8791 when it determines what dependencies are required in a
8792 package control file. The <tt>shlibs</tt> file format
8793 is described on <ref id="shlibs">.
8798 <sect id="pkg-controlfile">
8799 <heading>The main control information file: <tt>control</tt></heading>
8802 The most important control information file used by
8803 <prgn>dpkg</prgn> when it installs a package is
8804 <tt>control</tt>. It contains all the package's "vital
8809 The binary package control files of packages built from
8810 Debian sources are made by a special tool,
8811 <prgn>dpkg-gencontrol</prgn>, which reads
8812 <file>debian/control</file> and <file>debian/changelog</file> to
8813 find the information it needs. See <ref id="pkg-sourcepkg"> for
8818 The fields in binary package control files are listed in
8819 <ref id="binarycontrolfiles">.
8823 A description of the syntax of control files and the purpose
8824 of the fields is available in <ref id="controlfields">.
8829 <heading>Time Stamps</heading>
8832 See <ref id="timestamps">.
8837 <appendix id="pkg-sourcepkg">
8838 <heading>Source packages (from old Packaging Manual) </heading>
8841 The Debian binary packages in the distribution are generated
8842 from Debian sources, which are in a special format to assist
8843 the easy and automatic building of binaries.
8846 <sect id="pkg-sourcetools">
8847 <heading>Tools for processing source packages</heading>
8850 Various tools are provided for manipulating source packages;
8851 they pack and unpack sources and help build of binary
8852 packages and help manage the distribution of new versions.
8856 They are introduced and typical uses described here; see
8857 <manref name="dpkg-source" section="1"> for full
8858 documentation about their arguments and operation.
8862 For examples of how to construct a Debian source package,
8863 and how to use those utilities that are used by Debian
8864 source packages, please see the <prgn>hello</prgn> example
8868 <sect1 id="pkg-dpkg-source">
8870 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8875 This program is frequently used by hand, and is also
8876 called from package-independent automated building scripts
8877 such as <prgn>dpkg-buildpackage</prgn>.
8881 To unpack a package it is typically invoked with
8883 dpkg-source -x <var>.../path/to/filename</var>.dsc
8888 with the <file><var>filename</var>.tar.gz</file> and
8889 <file><var>filename</var>.diff.gz</file> (if applicable) in
8890 the same directory. It unpacks into
8891 <file><var>package</var>-<var>version</var></file>, and if
8893 <file><var>package</var>-<var>version</var>.orig</file>, in
8894 the current directory.
8898 To create a packed source archive it is typically invoked:
8900 dpkg-source -b <var>package</var>-<var>version</var>
8905 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8906 <file>.diff.gz</file> (if appropriate) in the current
8907 directory. <prgn>dpkg-source</prgn> does not clean the
8908 source tree first - this must be done separately if it is
8913 See also <ref id="pkg-sourcearchives">.</p>
8917 <sect1 id="pkg-dpkg-buildpackage">
8919 <prgn>dpkg-buildpackage</prgn> - overall package-building
8924 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8925 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8926 targets <tt>clean</tt>, <tt>build</tt> and
8927 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8928 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8929 source and binary package upload.
8933 It is usually invoked by hand from the top level of the
8934 built or unbuilt source directory. It may be invoked with
8935 no arguments; useful arguments include:
8936 <taglist compact="compact">
8937 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8940 Do not sign the <tt>.changes</tt> file or the
8941 source package <tt>.dsc</tt> file, respectively.</p>
8943 <tag><tt>-p<var>sign-command</var></tt></tag>
8946 Invoke <var>sign-command</var> instead of finding
8947 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8948 <var>sign-command</var> must behave just like
8949 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
8951 <tag><tt>-r<var>root-command</var></tt></tag>
8954 When root privilege is required, invoke the command
8955 <var>root-command</var>. <var>root-command</var>
8956 should invoke its first argument as a command, from
8957 the <prgn>PATH</prgn> if necessary, and pass its
8958 second and subsequent arguments to the command it
8959 calls. If no <var>root-command</var> is supplied
8960 then <var>dpkg-buildpackage</var> will take no
8961 special action to gain root privilege, so that for
8962 most packages it will have to be invoked as root to
8965 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8968 Two types of binary-only build and upload - see
8969 <manref name="dpkg-source" section="1">.
8976 <sect1 id="pkg-dpkg-gencontrol">
8978 <prgn>dpkg-gencontrol</prgn> - generates binary package
8983 This program is usually called from <file>debian/rules</file>
8984 (see <ref id="pkg-sourcetree">) in the top level of the source
8989 This is usually done just before the files and directories in the
8990 temporary directory tree where the package is being built have their
8991 permissions and ownerships set and the package is constructed using
8992 <prgn>dpkg-deb/</prgn>
8994 This is so that the control file which is produced has
8995 the right permissions
9000 <prgn>dpkg-gencontrol</prgn> must be called after all the
9001 files which are to go into the package have been placed in
9002 the temporary build directory, so that its calculation of
9003 the installed size of a package is correct.
9007 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9008 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9009 variable substitutions created by
9010 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9015 For a package which generates only one binary package, and
9016 which builds it in <file>debian/tmp</file> relative to the top
9017 of the source package, it is usually sufficient to call
9018 <prgn>dpkg-gencontrol</prgn>.
9022 Sources which build several binaries will typically need
9025 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9026 </example> The <tt>-P</tt> tells
9027 <prgn>dpkg-gencontrol</prgn> that the package is being
9028 built in a non-default directory, and the <tt>-p</tt>
9029 tells it which package's control file should be generated.
9033 <prgn>dpkg-gencontrol</prgn> also adds information to the
9034 list of files in <file>debian/files</file>, for the benefit of
9035 (for example) a future invocation of
9036 <prgn>dpkg-genchanges</prgn>.</p>
9039 <sect1 id="pkg-dpkg-shlibdeps">
9041 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9046 This program is usually called from <file>debian/rules</file>
9047 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9048 id="pkg-sourcetree">), in the top level of the source tree.
9052 Its arguments are executables.
9055 In a forthcoming dpkg version,
9056 <prgn>dpkg-shlibdeps</prgn> would be required to be
9057 called on shared libraries as well.
9060 They may be specified either in the locations in the
9061 source tree where they are created or in the locations
9062 in the temporary build tree where they are installed
9063 prior to binary package creation.
9065 </footnote> for which shared library dependencies should
9066 be included in the binary package's control file.
9070 If some of the found shared libraries should only
9071 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9072 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9073 by using the <tt>-d<var>dependency-field</var></tt> option
9074 before those executable(s). (Each <tt>-d</tt> option
9075 takes effect until the next <tt>-d</tt>.)
9079 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9080 output control file to be modified. Instead by default it
9081 adds to the <file>debian/substvars</file> file variable
9082 settings like <tt>shlibs:Depends</tt>. These variable
9083 settings must be referenced in dependency fields in the
9084 appropriate per-binary-package sections of the source
9089 For example, a package that generates an essential part
9090 which requires dependencies, and optional parts that
9091 which only require a recommendation, would separate those
9092 two sets of dependencies into two different fields.<footnote>
9093 At the time of writing, an example for this was the
9094 <package/xmms/ package, with Depends used for the xmms
9095 executable, Recommends for the plug-ins and Suggests for
9096 even more optional features provided by unzip.
9098 It can say in its <file>debian/rules</file>:
9100 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9101 -dRecommends <var>optionalpart anotheroptionalpart</var>
9103 and then in its main control file <file>debian/control</file>:
9106 Depends: ${shlibs:Pre-Depends}
9107 Recommends: ${shlibs:Recommends}
9113 Sources which produce several binary packages with
9114 different shared library dependency requirements can use
9115 the <tt>-p<var>varnameprefix</var></tt> option to override
9116 the default <tt>shlibs:</tt> prefix (one invocation of
9117 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9118 They can thus produce several sets of dependency
9119 variables, each of the form
9120 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9121 which can be referred to in the appropriate parts of the
9122 binary package control files.
9127 <sect1 id="pkg-dpkg-distaddfile">
9129 <prgn>dpkg-distaddfile</prgn> - adds a file to
9130 <file>debian/files</file>
9134 Some packages' uploads need to include files other than
9135 the source and binary package files.
9139 <prgn>dpkg-distaddfile</prgn> adds a file to the
9140 <file>debian/files</file> file so that it will be included in
9141 the <file>.changes</file> file when
9142 <prgn>dpkg-genchanges</prgn> is run.
9146 It is usually invoked from the <tt>binary</tt> target of
9147 <file>debian/rules</file>:
9149 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9151 The <var>filename</var> is relative to the directory where
9152 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9153 is usually the directory above the top level of the source
9154 tree. The <file>debian/rules</file> target should put the
9155 file there just before or just after calling
9156 <prgn>dpkg-distaddfile</prgn>.
9160 The <var>section</var> and <var>priority</var> are passed
9161 unchanged into the resulting <file>.changes</file> file.
9166 <sect1 id="pkg-dpkg-genchanges">
9168 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9173 This program is usually called by package-independent
9174 automatic building scripts such as
9175 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9180 It is usually called in the top level of a built source
9181 tree, and when invoked with no arguments will print out a
9182 straightforward <file>.changes</file> file based on the
9183 information in the source package's changelog and control
9184 file and the binary and source packages which should have
9190 <sect1 id="pkg-dpkg-parsechangelog">
9192 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9193 representation of a changelog
9197 This program is used internally by
9198 <prgn>dpkg-source</prgn> et al. It may also occasionally
9199 be useful in <file>debian/rules</file> and elsewhere. It
9200 parses a changelog, <file>debian/changelog</file> by default,
9201 and prints a control-file format representation of the
9202 information in it to standard output.
9206 <sect1 id="pkg-dpkg-architecture">
9208 <prgn>dpkg-architecture</prgn> - information about the build and
9213 This program can be used manually, but is also invoked by
9214 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9215 to set environment or make variables which specify the build and
9216 host architecture for the package building process.
9221 <sect id="pkg-sourcetree">
9222 <heading>The Debianised source tree</heading>
9225 The source archive scheme described later is intended to
9226 allow a Debianised source tree with some associated control
9227 information to be reproduced and transported easily. The
9228 Debianised source tree is a version of the original program
9229 with certain files added for the benefit of the
9230 Debianisation process, and with any other changes required
9231 made to the rest of the source code and installation
9236 The extra files created for Debian are in the subdirectory
9237 <file>debian</file> of the top level of the Debianised source
9238 tree. They are described below.
9241 <sect1 id="pkg-debianrules">
9242 <heading><file>debian/rules</file> - the main building script</heading>
9245 See <ref id="debianrules">.
9250 <sect1 id="pkg-dpkgchangelog">
9251 <heading><file>debian/changelog</file></heading>
9254 See <ref id="dpkgchangelog">.
9258 It is recommended that the entire changelog be encoded in the
9259 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9261 <url id="http://www.unicode.org/"
9262 name="Unicode">.<footnote>
9264 Support for Unicode, and specifically UTF-8, is
9265 steadily increasing among popular applications in
9266 Debian. For example, in unstable, GNOME 2 has
9267 excellent support (almost level 2) in almost all its
9268 applications; the big remaining one is gnome-terminal,
9269 of which one requires development versions in order to
9270 support UTF-8 (available in Debian experimental now if
9271 you want to play). I think that by the time sarge is
9272 released, UTF-8 support will start to hit critical
9275 I think it is fairly obvious that we need to
9276 eventually transition to UTF-8 for our package
9277 infrastructure; it is really the only sane charset in
9278 an international environment. Now, we can't switch to
9279 using UTF-8 for package control fields and the like
9280 until dpkg has better support, but one thing we can
9281 start doing today is requesting that Debian changelogs
9282 are UTF-8 encoded. At some point in time, we can start
9283 requiring them to do so.
9286 Checking for non-UTF8 characters in a changelog is
9287 trivial. Dump the file through
9288 <example>iconv -f utf-8 -t ucs-4</example>
9289 discard the output, and check the return
9290 value. If there are any characters in the stream
9291 which are invalid UTF-8 sequences, iconv will exit
9292 with an error code; and this will be the case for the
9293 vast majority of other character sets.
9298 <sect2><heading>Defining alternative changelog formats
9302 It is possible to use a different format to the standard
9303 one, by providing a parser for the format you wish to
9308 In order to have <tt>dpkg-parsechangelog</tt> run your
9309 parser, you must include a line within the last 40 lines
9310 of your file matching the Perl regular expression:
9311 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9312 parentheses should be the name of the format. For
9313 example, you might say:
9315 @@@ changelog-format: joebloggs @@@
9317 Changelog format names are non-empty strings of alphanumerics.
9321 If such a line exists then <tt>dpkg-parsechangelog</tt>
9322 will look for the parser as
9323 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9325 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9326 it is an error for it not to find it, or for it not to
9327 be an executable program. The default changelog format
9328 is <tt>dpkg</tt>, and a parser for it is provided with
9329 the <tt>dpkg</tt> package.
9333 The parser will be invoked with the changelog open on
9334 standard input at the start of the file. It should read
9335 the file (it may seek if it wishes) to determine the
9336 information required and return the parsed information
9337 to standard output in the form of a series of control
9338 fields in the standard format. By default it should
9339 return information about only the most recent version in
9340 the changelog; it should accept a
9341 <tt>-v<var>version</var></tt> option to return changes
9342 information from all versions present <em>strictly
9343 after</em> <var>version</var>, and it should then be an
9344 error for <var>version</var> not to be present in the
9350 <list compact="compact">
9351 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9352 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9353 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9354 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9355 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9356 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9357 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9362 If several versions are being returned (due to the use
9363 of <tt>-v</tt>), the urgency value should be of the
9364 highest urgency code listed at the start of any of the
9365 versions requested followed by the concatenated
9366 (space-separated) comments from all the versions
9367 requested; the maintainer, version, distribution and
9368 date should always be from the most recent version.
9372 For the format of the <tt>Changes</tt> field see
9373 <ref id="f-Changes">.
9377 If the changelog format which is being parsed always or
9378 almost always leaves a blank line between individual
9379 change notes these blank lines should be stripped out,
9380 so as to make the resulting output compact.
9384 If the changelog format does not contain date or package
9385 name information this information should be omitted from
9386 the output. The parser should not attempt to synthesise
9387 it or find it from other sources.
9391 If the changelog does not have the expected format the
9392 parser should exit with a nonzero exit status, rather
9393 than trying to muddle through and possibly generating
9398 A changelog parser may not interact with the user at
9404 <sect1 id="pkg-srcsubstvars">
9405 <heading><file>debian/substvars</file> and variable substitutions</heading>
9408 See <ref id="substvars">.
9414 <heading><file>debian/files</file></heading>
9417 See <ref id="debianfiles">.
9421 <sect1><heading><file>debian/tmp</file>
9425 This is the canonical temporary location for the
9426 construction of binary packages by the <tt>binary</tt>
9427 target. The directory <file>tmp</file> serves as the root of
9428 the filesystem tree as it is being constructed (for
9429 example, by using the package's upstream makefiles install
9430 targets and redirecting the output there), and it also
9431 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9432 id="pkg-bincreating">.
9436 If several binary packages are generated from the same
9437 source tree it is usual to use several
9438 <file>debian/tmp<var>something</var></file> directories, for
9439 example <file>tmp-a</file> or <file>tmp-doc</file>.
9443 Whatever <file>tmp</file> directories are created and used by
9444 <tt>binary</tt> must of course be removed by the
9445 <tt>clean</tt> target.</p></sect1>
9449 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9453 As it exists on the FTP site, a Debian source package
9454 consists of three related files. You must have the right
9455 versions of all three to be able to use them.
9460 <tag>Debian source control file - <tt>.dsc</tt></tag>
9462 This file is a control file used by <prgn>dpkg-source</prgn>
9463 to extract a source package.
9464 See <ref id="debiansourcecontrolfiles">.
9468 Original source archive -
9470 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9476 This is a compressed (with <tt>gzip -9</tt>)
9477 <prgn>tar</prgn> file containing the source code from
9478 the upstream authors of the program.
9483 Debianisation diff -
9485 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9491 This is a unified context diff (<tt>diff -u</tt>)
9492 giving the changes which are required to turn the
9493 original source into the Debian source. These changes
9494 may only include editing and creating plain files.
9495 The permissions of files, the targets of symbolic
9496 links and the characteristics of special files or
9497 pipes may not be changed and no files may be removed
9502 All the directories in the diff must exist, except the
9503 <file>debian</file> subdirectory of the top of the source
9504 tree, which will be created by
9505 <prgn>dpkg-source</prgn> if necessary when unpacking.
9509 The <prgn>dpkg-source</prgn> program will
9510 automatically make the <file>debian/rules</file> file
9511 executable (see below).</p></item>
9516 If there is no original source code - for example, if the
9517 package is specially prepared for Debian or the Debian
9518 maintainer is the same as the upstream maintainer - the
9519 format is slightly different: then there is no diff, and the
9521 <file><var>package</var>_<var>version</var>.tar.gz</file>,
9522 and preferably contains a directory named
9523 <file><var>package</var>-<var>version</var></file>.
9528 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9531 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9532 Debian source package. However, if it is not available it
9533 is possible to unpack a Debian source archive as follows:
9534 <enumlist compact="compact">
9537 Untar the tarfile, which will create a <file>.orig</file>
9541 <p>Rename the <file>.orig</file> directory to
9542 <file><var>package</var>-<var>version</var></file>.</p>
9546 Create the subdirectory <file>debian</file> at the top of
9547 the source tree.</p>
9549 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9551 <item><p>Untar the tarfile again if you want a copy of the original
9552 source code alongside the Debianised version.</p>
9557 It is not possible to generate a valid Debian source archive
9558 without using <prgn>dpkg-source</prgn>. In particular,
9559 attempting to use <prgn>diff</prgn> directly to generate the
9560 <file>.diff.gz</file> file will not work.
9564 <heading>Restrictions on objects in source packages</heading>
9567 The source package may not contain any hard links
9569 This is not currently detected when building source
9570 packages, but only when extracting
9574 Hard links may be permitted at some point in the
9575 future, but would require a fair amount of
9577 </footnote>, device special files, sockets or setuid or
9580 Setgid directories are allowed.
9585 The source packaging tools manage the changes between the
9586 original and Debianised source using <prgn>diff</prgn> and
9587 <prgn>patch</prgn>. Turning the original source tree as
9588 included in the <file>.orig.tar.gz</file> into the debianised
9589 source must not involve any changes which cannot be
9590 handled by these tools. Problematic changes which cause
9591 <prgn>dpkg-source</prgn> to halt with an error when
9592 building the source package are:
9593 <list compact="compact">
9594 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9596 <item><p>Changing the targets of symbolic links.</p>
9598 <item><p>Creating directories, other than <file>debian</file>.</p>
9600 <item><p>Changes to the contents of binary files.</p></item>
9601 </list> Changes which cause <prgn>dpkg-source</prgn> to
9602 print a warning but continue anyway are:
9603 <list compact="compact">
9606 Removing files, directories or symlinks.
9608 Renaming a file is not treated specially - it is
9609 seen as the removal of the old file (which
9610 generates a warning, but is otherwise ignored),
9611 and the creation of the new one.
9617 Changed text files which are missing the usual final
9618 newline (either in the original or the modified
9623 Changes which are not represented, but which are not detected by
9624 <prgn>dpkg-source</prgn>, are:
9625 <list compact="compact">
9626 <item><p>Changing the permissions of files (other than
9627 <file>debian/rules</file>) and directories.</p></item>
9632 The <file>debian</file> directory and <file>debian/rules</file>
9633 are handled specially by <prgn>dpkg-source</prgn> - before
9634 applying the changes it will create the <file>debian</file>
9635 directory, and afterwards it will make
9636 <file>debian/rules</file> world-exectuable.
9642 <appendix id="pkg-controlfields">
9643 <heading>Control files and their fields (from old Packaging Manual)</heading>
9646 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9647 data in a common format, known as control files. Binary and
9648 source packages have control data as do the <file>.changes</file>
9649 files which control the installation of uploaded files, and
9650 <prgn>dpkg</prgn>'s internal databases are in a similar
9655 <heading>Syntax of control files</heading>
9658 See <ref id="controlsyntax">.
9662 It is important to note that there are several fields which
9663 are optional as far as <prgn>dpkg</prgn> and the related
9664 tools are concerned, but which must appear in every Debian
9665 package, or whose omission may cause problems.
9670 <heading>List of fields</heading>
9673 See <ref id="controlfieldslist">.
9677 This section now contains only the fields that didn't belong
9678 to the Policy manual.
9681 <sect1 id="pkg-f-Filename">
9682 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9685 These fields in <tt>Packages</tt> files give the
9686 filename(s) of (the parts of) a package in the
9687 distribution directories, relative to the root of the
9688 Debian hierarchy. If the package has been split into
9689 several parts the parts are all listed in order, separated
9694 <sect1 id="pkg-f-Size">
9695 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9698 These fields in <file>Packages</file> files give the size (in
9699 bytes, expressed in decimal) and MD5 checksum of the
9700 file(s) which make(s) up a binary package in the
9701 distribution. If the package is split into several parts
9702 the values for the parts are listed in order, separated by
9707 <sect1 id="pkg-f-Status">
9708 <heading><tt>Status</tt></heading>
9711 This field in <prgn>dpkg</prgn>'s status file records
9712 whether the user wants a package installed, removed or
9713 left alone, whether it is broken (requiring
9714 reinstallation) or not and what its current state on the
9715 system is. Each of these pieces of information is a
9720 <sect1 id="pkg-f-Config-Version">
9721 <heading><tt>Config-Version</tt></heading>
9724 If a package is not installed or not configured, this
9725 field in <prgn>dpkg</prgn>'s status file records the last
9726 version of the package which was successfully
9731 <sect1 id="pkg-f-Conffiles">
9732 <heading><tt>Conffiles</tt></heading>
9735 This field in <prgn>dpkg</prgn>'s status file contains
9736 information about the automatically-managed configuration
9737 files held by a package. This field should <em>not</em>
9738 appear anywhere in a package!
9743 <heading>Obsolete fields</heading>
9746 These are still recognised by <prgn>dpkg</prgn> but should
9747 not appear anywhere any more.
9749 <taglist compact="compact">
9751 <tag><tt>Revision</tt></tag>
9752 <tag><tt>Package-Revision</tt></tag>
9753 <tag><tt>Package_Revision</tt></tag>
9755 The Debian revision part of the package version was
9756 at one point in a separate control file field. This
9757 field went through several names.
9760 <tag><tt>Recommended</tt></tag>
9761 <item>Old name for <tt>Recommends</tt>.</item>
9763 <tag><tt>Optional</tt></tag>
9764 <item>Old name for <tt>Suggests</tt>.</item>
9766 <tag><tt>Class</tt></tag>
9767 <item>Old name for <tt>Priority</tt>.</item>
9776 <appendix id="pkg-conffiles">
9777 <heading>Configuration file handling (from old Packaging Manual)</heading>
9780 <prgn>dpkg</prgn> can do a certain amount of automatic
9781 handling of package configuration files.
9785 Whether this mechanism is appropriate depends on a number of
9786 factors, but basically there are two approaches to any
9787 particular configuration file.
9791 The easy method is to ship a best-effort configuration in the
9792 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9793 handle updates. If the user is unlikely to want to edit the
9794 file, but you need them to be able to without losing their
9795 changes, and a new package with a changed version of the file
9796 is only released infrequently, this is a good approach.
9800 The hard method is to build the configuration file from
9801 scratch in the <prgn>postinst</prgn> script, and to take the
9802 responsibility for fixing any mistakes made in earlier
9803 versions of the package automatically. This will be
9804 appropriate if the file is likely to need to be different on
9808 <sect><heading>Automatic handling of configuration files by
9813 A package may contain a control area file called
9814 <tt>conffiles</tt>. This file should be a list of filenames
9815 of configuration files needing automatic handling, separated
9816 by newlines. The filenames should be absolute pathnames,
9817 and the files referred to should actually exist in the
9822 When a package is upgraded <prgn>dpkg</prgn> will process
9823 the configuration files during the configuration stage,
9824 shortly before it runs the package's <prgn>postinst</prgn>
9829 For each file it checks to see whether the version of the
9830 file included in the package is the same as the one that was
9831 included in the last version of the package (the one that is
9832 being upgraded from); it also compares the version currently
9833 installed on the system with the one shipped with the last
9838 If neither the user nor the package maintainer has changed
9839 the file, it is left alone. If one or the other has changed
9840 their version, then the changed version is preferred - i.e.,
9841 if the user edits their file, but the package maintainer
9842 doesn't ship a different version, the user's changes will
9843 stay, silently, but if the maintainer ships a new version
9844 and the user hasn't edited it the new version will be
9845 installed (with an informative message). If both have
9846 changed their version the user is prompted about the problem
9847 and must resolve the differences themselves.
9851 The comparisons are done by calculating the MD5 message
9852 digests of the files, and storing the MD5 of the file as it
9853 was included in the most recent version of the package.
9857 When a package is installed for the first time
9858 <prgn>dpkg</prgn> will install the file that comes with it,
9859 unless that would mean overwriting a file already on the
9864 However, note that <prgn>dpkg</prgn> will <em>not</em>
9865 replace a conffile that was removed by the user (or by a
9866 script). This is necessary because with some programs a
9867 missing file produces an effect hard or impossible to
9868 achieve in another way, so that a missing file needs to be
9869 kept that way if the user did it.
9873 Note that a package should <em>not</em> modify a
9874 <prgn>dpkg</prgn>-handled conffile in its maintainer
9875 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9876 the user confusing and possibly dangerous options for
9877 conffile update when the package is upgraded.</p>
9880 <sect><heading>Fully-featured maintainer script configuration
9885 For files which contain site-specific information such as
9886 the hostname and networking details and so forth, it is
9887 better to create the file in the package's
9888 <prgn>postinst</prgn> script.
9892 This will typically involve examining the state of the rest
9893 of the system to determine values and other information, and
9894 may involve prompting the user for some information which
9895 can't be obtained some other way.
9899 When using this method there are a couple of important
9900 issues which should be considered:
9904 If you discover a bug in the program which generates the
9905 configuration file, or if the format of the file changes
9906 from one version to the next, you will have to arrange for
9907 the postinst script to do something sensible - usually this
9908 will mean editing the installed configuration file to remove
9909 the problem or change the syntax. You will have to do this
9910 very carefully, since the user may have changed the file,
9911 perhaps to fix the very problem that your script is trying
9912 to deal with - you will have to detect these situations and
9913 deal with them correctly.
9917 If you do go down this route it's probably a good idea to
9918 make the program that generates the configuration file(s) a
9919 separate program in <file>/usr/sbin</file>, by convention called
9920 <file><var>package</var>config</file> and then run that if
9921 appropriate from the post-installation script. The
9922 <tt><var>package</var>config</tt> program should not
9923 unquestioningly overwrite an existing configuration - if its
9924 mode of operation is geared towards setting up a package for
9925 the first time (rather than any arbitrary reconfiguration
9926 later) you should have it check whether the configuration
9927 already exists, and require a <tt>--force</tt> flag to
9928 overwrite it.</p></sect>
9931 <appendix id="pkg-alternatives"><heading>Alternative versions of
9932 an interface - <prgn>update-alternatives</prgn> (from old
9937 When several packages all provide different versions of the
9938 same program or file it is useful to have the system select a
9939 default, but to allow the system administrator to change it
9940 and have their decisions respected.
9944 For example, there are several versions of the <prgn>vi</prgn>
9945 editor, and there is no reason to prevent all of them from
9946 being installed at once, each under their own name
9947 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9948 Nevertheless it is desirable to have the name <tt>vi</tt>
9949 refer to something, at least by default.
9953 If all the packages involved cooperate, this can be done with
9954 <prgn>update-alternatives</prgn>.
9958 Each package provides its own version under its own name, and
9959 calls <prgn>update-alternatives</prgn> in its postinst to
9960 register its version (and again in its prerm to deregister
9965 See the man page <manref name="update-alternatives"
9966 section="8"> for details.
9970 If <prgn>update-alternatives</prgn> does not seem appropriate
9971 you may wish to consider using diversions instead.</p>
9974 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9975 package's version of a file (from old Packaging Manual)
9979 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9980 when it reinstalls the package it belongs to, and to have it
9981 put the file from the package somewhere else instead.
9985 This can be used locally to override a package's version of a
9986 file, or by one package to override another's version (or
9987 provide a wrapper for it).
9991 Before deciding to use a diversion, read <ref
9992 id="pkg-alternatives"> to see if you really want a diversion
9993 rather than several alternative versions of a program.
9997 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9998 and updated by a special program <prgn>dpkg-divert</prgn>.
9999 Please see <manref name="dpkg-divert" section="8"> for full
10000 details of its operation.
10004 When a package wishes to divert a file from another, it should
10005 call <prgn>dpkg-divert</prgn> in its preinst to add the
10006 diversion and rename the existing file. For example,
10007 supposing that a <prgn>smailwrapper</prgn> package wishes to
10008 install a wrapper around <file>/usr/sbin/smail</file>:
10010 if [ install = "$1" ]; then
10011 dpkg-divert --package smailwrapper --add --rename \
10012 --divert /usr/sbin/smail.real /usr/sbin/smail
10014 </example> Testing <tt>$1</tt> is necessary so that the script
10015 doesn't try to add the diversion again when
10016 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10017 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10018 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10019 get installed as the true version.
10023 The postrm has to do the reverse:
10025 if [ remove = "$1" ]; then
10026 dpkg-divert --package smailwrapper --remove --rename \
10027 --divert /usr/sbin/smail.real /usr/sbin/smail
10033 Do not attempt to divert a file which is vitally important for
10034 the system's operation - when using <prgn>dpkg-divert</prgn>
10035 there is a time, after it has been diverted but before
10036 <prgn>dpkg</prgn> has installed the new version, when the file
10037 does not exist.</p>
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