1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy" id="http://packages.debian.org/debian-policy"></package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>.
168 Also available from the same directory are several other
169 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
170 and <file>policy.ps.gz</file>.
174 The <package>debian-policy</package> package also includes the file
175 <file>upgrading-checklist.txt</file> which indicates policy
176 changes between versions of this document.
181 <heading>Authors and Maintainers</heading>
184 Originally called "Debian GNU/Linux Policy Manual", this
185 manual was initially written in 1996 by Ian Jackson.
186 It was revised on November 27th, 1996 by David A. Morris.
187 Christian Schwarz added new sections on March 15th, 1997,
188 and reworked/restructured it in April-July 1997.
189 Christoph Lameter contributed the "Web Standard".
190 Julian Gilbey largely restructured it in 2001.
194 Since September 1998, the responsibility for the contents of
195 this document lies on the <url name="debian-policy mailing list"
196 id="mailto:debian-policy@lists.debian.org">. Proposals
197 are discussed there and inserted into policy after a certain
198 consensus is established.
199 <!-- insert shameless policy-process plug here eventually -->
200 The actual editing is done by a group of maintainers that have
201 no editorial powers. These are the current maintainers:
204 <item>Julian Gilbey</item>
205 <item>Branden Robinson</item>
206 <item>Josip Rodin</item>
207 <item>Manoj Srivastava</item>
212 While the authors of this document have tried hard to avoid
213 typos and other errors, these do still occur. If you discover
214 an error in this manual or if you want to give any
215 comments, suggestions, or criticisms please send an email to
216 the Debian Policy List,
217 <email>debian-policy@lists.debian.org</email>, or submit a
218 bug report against the <tt>debian-policy</tt> package.
222 Please do not try to reach the individual authors or maintainers
223 of the Policy Manual regarding changes to the Policy.
228 <heading>Related documents</heading>
231 There are several other documents other than this Policy Manual
232 that are necessary to fully understand some Debian policies and
237 The external "sub-policy" documents are referred to in:
238 <list compact="compact">
239 <item><ref id="fhs"></item>
240 <item><ref id="virtual_pkg"></item>
241 <item><ref id="menus"></item>
242 <item><ref id="mime"></item>
243 <item><ref id="perl"></item>
244 <item><ref id="maintscriptprompt"></item>
245 <item><ref id="emacs"></item>
250 In addition to those, which carry the weight of policy, there
251 is the Debian Developer's Reference. This document describes
252 procedures and resources for Debian developers, but it is
253 <em>not</em> normative; rather, it includes things that don't
254 belong into the Policy, such as best practices for developers.
258 The Developer's Reference is available in the
259 <package>developers-reference</package> package.
260 It's also available from the Debian web mirrors at
261 <tt><url name="/doc/developers-reference/"
262 id="http://www.debian.org/doc/developers-reference/"></tt>.
270 <heading>The Debian Archive</heading>
273 The Debian GNU/Linux system is maintained and distributed as a
274 collection of <em>packages</em>. Since there are so many of
275 them (currently well over 6000), they are split into
276 <em>sections</em> and given <em>priorities</em> to simplify
277 the handling of them.
281 The effort of the Debian project is to build a free operating
282 system, but not every package we want to make accessible is
283 <em>free</em> in our sense (see the Debian Free Software
284 Guidelines, below), or may be imported/exported without
285 restrictions. Thus, the archive is split into the sections
286 based on their licenses and other restrictions.
290 The aims of this are:
292 <list compact="compact">
293 <item>to allow us to make as much software available as we can</item>
294 <item>to allow us to encourage everyone to write free software,
296 <item>to allow us to make it easy for people to produce
297 CD-ROMs of our system without violating any licenses,
298 import/export restrictions, or any other laws.</item>
303 The <em>main</em> and the <em>non-US/main</em> sections
304 together form the <em>Debian GNU/Linux distribution</em>.
308 Packages in the other sections are not considered to be part
309 of the Debian distribution, although we support their use and
310 provide infrastructure for them (such as our bug-tracking
311 system and mailing lists). This Debian Policy Manual applies
312 to these packages as well.
316 <heading>The Debian Free Software Guidelines</heading>
318 The Debian Free Software Guidelines (DFSG) form our
319 definition of "free software". These are:
321 <tag>Free Redistribution
324 The license of a Debian component may not restrict any
325 party from selling or giving away the software as a
326 component of an aggregate software distribution
327 containing programs from several different
328 sources. The license may not require a royalty or
329 other fee for such sale.
334 The program must include source code, and must allow
335 distribution in source code as well as compiled form.
340 The license must allow modifications and derived
341 works, and must allow them to be distributed under the
342 same terms as the license of the original software.
344 <tag>Integrity of The Author's Source Code
347 The license may restrict source-code from being
348 distributed in modified form <em>only</em> if the
349 license allows the distribution of "patch files"
350 with the source code for the purpose of modifying the
351 program at build time. The license must explicitly
352 permit distribution of software built from modified
353 source code. The license may require derived works to
354 carry a different name or version number from the
355 original software. (This is a compromise. The Debian
356 Project encourages all authors to not restrict any
357 files, source or binary, from being modified.)
359 <tag>No Discrimination Against Persons or Groups
362 The license must not discriminate against any person
365 <tag>No Discrimination Against Fields of Endeavor
368 The license must not restrict anyone from making use
369 of the program in a specific field of endeavor. For
370 example, it may not restrict the program from being
371 used in a business, or from being used for genetic
374 <tag>Distribution of License
377 The rights attached to the program must apply to all
378 to whom the program is redistributed without the need
379 for execution of an additional license by those
382 <tag>License Must Not Be Specific to Debian
385 The rights attached to the program must not depend on
386 the program's being part of a Debian system. If the
387 program is extracted from Debian and used or
388 distributed without Debian but otherwise within the
389 terms of the program's license, all parties to whom
390 the program is redistributed must have the same
391 rights as those that are granted in conjunction with
394 <tag>License Must Not Contaminate Other Software
397 The license must not place restrictions on other
398 software that is distributed along with the licensed
399 software. For example, the license must not insist
400 that all other programs distributed on the same medium
401 must be free software.
403 <tag>Example Licenses
406 The "GPL," "BSD," and "Artistic" licenses are examples of
407 licenses that we consider <em>free</em>.
414 <heading>Sections</heading>
417 <heading>The main section</heading>
420 Every package in <em>main</em> and <em>non-US/main</em>
421 must comply with the DFSG (Debian Free Software
426 In addition, the packages in <em>main</em>
427 <list compact="compact">
429 must not require a package outside of <em>main</em>
430 for compilation or execution (thus, the package must
431 not declare a "Depends", "Recommends", or
432 "Build-Depends" relationship on a non-<em>main</em>
436 must not be so buggy that we refuse to support them,
440 must meet all policy requirements presented in this
447 Similarly, the packages in <em>non-US/main</em>
448 <list compact="compact">
450 must not require a package outside of <em>main</em>
451 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
458 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
479 must not be so buggy that we refuse to support them,
483 must meet all policy requirements presented in this
490 Furthermore, packages in <em>contrib</em> must not require
491 a package in a <em>non-US</em> section for compilation or
496 Examples of packages which would be included in
497 <em>contrib</em> or <em>non-US/contrib</em> are:
498 <list compact="compact">
500 free packages which require <em>contrib</em>,
501 <em>non-free</em> packages or packages which are not
502 in our archive at all for compilation or execution,
506 wrapper packages or other sorts of free accessories for
513 <sect1 id="non-free">
514 <heading>The non-free section</heading>
517 Packages must be placed in <em>non-free</em> or
518 <em>non-US/non-free</em> if they are not compliant with
519 the DFSG or are encumbered by patents or other legal
520 issues that make their distribution problematic.
524 In addition, the packages in <em>non-free</em> and
525 <em>non-US/non-free</em>
526 <list compact="compact">
528 must not be so buggy that we refuse to support them,
532 must meet all policy requirements presented in this
533 manual that it is possible for them to meet.
535 It is possible that there are policy
536 requirements which the package is unable to
537 meet, for example, if the source is
538 unavailable. These situations will need to be
539 handled on a case-by-case basis.
547 <heading>The non-US sections</heading>
550 Non-free programs with cryptographic program code need to
551 be stored on the <em>non-us</em> server because of export
552 restrictions of the U.S.
556 Programs which use patented algorithms that have a
557 restricted license also need to be stored on "non-us",
558 since that is located in a country where it is not allowed
559 to patent algorithms.
563 A package depends on another package which is distributed
564 via the non-us server has to be stored on the non-us
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of
575 its copyright and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Subsections</heading>
653 The packages in the sections <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further
655 into <em>subsections</em> to simplify handling.
659 The section and subsection for each package should be
660 specified in the package's <tt>Section</tt> control
661 record (see <ref id="f-Section">).
662 However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
668 <em>subsection</em> if the package is in the
669 <em>main</em> section,
672 <em>section/subsection</em> if the package is in
673 the <em>contrib</em> or <em>non-free</em> section,
677 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
678 <tt>non-US/non-free</tt> if the package is in
679 <em>non-US/main</em>, <em>non-US/contrib</em> or
680 <em>non-US/non-free</em> respectively.
686 The Debian archive maintainers provide the authoritative
687 list of subsections. At present, they are:
688 <em>admin</em>, <em>base</em>, <em>comm</em>,
689 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
690 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
691 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
692 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
693 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
694 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
695 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
696 <em>otherosfs</em>, <em>perl</em>, <em>python</em>
697 <em>science</em>, <em>shells</em>,
698 <em>sound</em>, <em>tex</em>, <em>text</em>,
699 <em>utils</em>, <em>web</em>, <em>x11</em>.
703 <sect id="priorities">
704 <heading>Priorities</heading>
707 Each package should have a <em>priority</em> value, which is
708 included in the package's <em>control record</em>
709 (see <ref id="f-Priority">).
710 This information is used by the Debian package management tools to
711 separate high-priority packages from less-important packages.
715 The following <em>priority levels</em> are recognised by the
716 Debian package management tools.
718 <tag><tt>required</tt></tag>
720 Packages which are necessary for the proper
721 functioning of the system. You must not remove these
722 packages or your system may become totally broken and
723 you may not even be able to use <prgn>dpkg</prgn> to
724 put things back. Systems with only the
725 <tt>required</tt> packages are probably unusable, but
726 they do have enough functionality to allow the
727 sysadmin to boot and install more software.
729 <tag><tt>important</tt></tag>
731 Important programs, including those which one would
732 expect to find on any Unix-like system. If the
733 expectation is that an experienced Unix person who
734 found it missing would say "What on earth is going on,
735 where is <prgn>foo</prgn>?", it must be an
736 <tt>important</tt> package.<footnote>
737 This is an important criterion because we are
738 trying to produce, amongst other things, a free
741 Other packages without which the system will not run
742 well or be usable must also have priority
743 <tt>important</tt>. This does
744 <em>not</em> include Emacs, the X Window System, TeX
745 or any other large applications. The
746 <tt>important</tt> packages are just a bare minimum of
747 commonly-expected and necessary tools.
749 <tag><tt>standard</tt></tag>
751 These packages provide a reasonably small but not too
752 limited character-mode system. This is what will be
753 installed by default if the user doesn't select anything
754 else. It doesn't include many large applications.
756 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
767 <tag><tt>extra</tt></tag>
769 This contains all packages that conflict with others
770 with required, important, standard or optional
771 priorities, or are only likely to be useful if you
772 already know what they are or have specialised
779 Packages must not depend on packages with lower priority
780 values (excluding build-time dependencies). In order to
781 ensure this, the priorities of one or more packages may need
790 <heading>Binary packages</heading>
793 The Debian GNU/Linux distribution is based on the Debian
794 package management system, called <prgn>dpkg</prgn>. Thus,
795 all packages in the Debian distribution must be provided
796 in the <tt>.deb</tt> file format.
800 <heading>The package name</heading>
803 Every package must have a name that's unique within the Debian
808 The package name is included in the control field
809 <tt>Package</tt>, the format of which is described
810 in <ref id="f-Package">.
811 The package name is also included as a part of the file name
812 of the <tt>.deb</tt> file.
817 <heading>The version of a package</heading>
820 Every package has a version number recorded in its
821 <tt>Version</tt> control file field, described in
822 <ref id="f-Version">.
826 The package management system imposes an ordering on version
827 numbers, so that it can tell whether packages are being up- or
828 downgraded and so that package system front end applications
829 can tell whether a package it finds available is newer than
830 the one installed on the system. The version number format
831 has the most significant parts (as far as comparison is
832 concerned) at the beginning.
836 If an upstream package has problematic version numbers they
837 should be converted to a sane form for use in the
838 <tt>Version</tt> field.
842 <heading>Version numbers based on dates</heading>
845 In general, Debian packages should use the same version
846 numbers as the upstream sources.
850 However, in some cases where the upstream version number is
851 based on a date (e.g., a development "snapshot" release) the
852 package management system cannot handle these version
853 numbers without epochs. For example, dpkg will consider
854 "96May01" to be greater than "96Dec24".
858 To prevent having to use epochs for every new upstream
859 version, the version number should be changed to the
860 following format in such cases: "19960501", "19961224". It
861 is up to the maintainer whether he/she wants to bother the
862 upstream maintainer to change the version numbers upstream,
867 Note that other version formats based on dates which are
868 parsed correctly by the package management system should
869 <em>not</em> be changed.
873 Native Debian packages (i.e., packages which have been
874 written especially for Debian) whose version numbers include
875 dates should always use the "YYYYMMDD" format.
882 <heading>The maintainer of a package</heading>
885 Every package must have a Debian maintainer (the
886 maintainer may be one person or a group of people
887 reachable from a common email address, such as a mailing
888 list). The maintainer is responsible for ensuring that
889 the package is placed in the appropriate distributions.
893 The maintainer must be specified in the
894 <tt>Maintainer</tt> control field with their correct name
895 and a working email address. If one person maintains
896 several packages, he/she should try to avoid having
897 different forms of their name and email address in
898 the <tt>Maintainer</tt> fields of those packages.
902 The format of the <tt>Maintainer</tt> control field is
903 described in <ref id="f-Maintainer">.
907 If the maintainer of a package quits from the Debian
908 project, "Debian QA Group"
909 <email>packages@qa.debian.org</email> takes over the
910 maintainership of the package until someone else
911 volunteers for that task. These packages are called
912 <em>orphaned packages</em>.<footnote>
913 The detailed procedure for doing this gracefully can
914 be found in the Debian Developer's Reference,
915 see <ref id="related">.
920 <sect id="descriptions">
921 <heading>The description of a package</heading>
924 Every Debian package must have an extended description
925 stored in the appropriate field of the control record.
926 The technical information about the format of the
927 <tt>Description</tt> field is in <ref id="f-Description">.
931 The description should describe the package (the program) to a
932 user (system administrator) who has never met it before so that
933 they have enough information to decide whether they want to
934 install it. This description should not just be copied verbatim
935 from the program's documentation.
939 Put important information first, both in the synopsis and
940 extended description. Sometimes only the first part of the
941 synopsis or of the description will be displayed. You can
942 assume that there will usually be a way to see the whole
943 extended description.
947 The description should also give information about the
948 significant dependencies and conflicts between this package
949 and others, so that the user knows why these dependencies and
950 conflicts have been declared.
954 Instructions for configuring or using the package should
955 not be included (that is what installation scripts,
956 manual pages, info files, etc., are for). Copyright
957 statements and other administrivia should not be included
958 either (that is what the copyright file is for).
961 <sect1 id="synopsis"><heading>The single line synopsis</heading>
964 The single line synopsis should be kept brief - certainly
969 Do not include the package name in the synopsis line. The
970 display software knows how to display this already, and you
971 do not need to state it. Remember that in many situations
972 the user may only see the synopsis line - make it as
973 informative as you can.
978 <sect1 id="extendeddesc"><heading>The extended description</heading>
981 Do not try to continue the single line synopsis into the
982 extended description. This will not work correctly when
983 the full description is displayed, and makes no sense
984 where only the summary (the single line synopsis) is
989 The extended description should describe what the package
990 does and how it relates to the rest of the system (in terms
991 of, for example, which subsystem it is which part of).
995 The description field needs to make sense to anyone, even
996 people who have no idea about any of the things the
997 package deals with.<footnote>
998 The blurb that comes with a program in its
999 announcements and/or <prgn>README</prgn> files is
1000 rarely suitable for use in a description. It is
1001 usually aimed at people who are already in the
1002 community where the package is used.
1011 <heading>Dependencies</heading>
1014 Every package must specify the dependency information
1015 about other packages that are required for the first to
1020 For example, a dependency entry must be provided for any
1021 shared libraries required by a dynamically-linked executable
1022 binary in a package.
1026 Packages are not required to declare any dependencies they
1027 have on other packages which are marked <tt>Essential</tt>
1028 (see below), and should not do so unless they depend on a
1029 particular version of that package.
1033 Sometimes, a package requires another package to be installed
1034 <em>and</em> configured before it can be installed. In this
1035 case, you must specify a <tt>Pre-Depends</tt> entry for
1040 You should not specify a <tt>Pre-Depends</tt> entry for a
1041 package before this has been discussed on the
1042 <tt>debian-devel</tt> mailing list and a consensus about
1043 doing that has been reached.
1047 The format of the package interrelationship control fields is
1048 described in <ref id="relationships">.
1052 <sect id="virtual_pkg">
1053 <heading>Virtual packages</heading>
1056 Sometimes, there are several packages which offer
1057 more-or-less the same functionality. In this case, it's
1058 useful to define a <em>virtual package</em> whose name
1059 describes that common functionality. (The virtual
1060 packages only exist logically, not physically; that's why
1061 they are called <em>virtual</em>.) The packages with this
1062 particular function will then <em>provide</em> the virtual
1063 package. Thus, any other package requiring that function
1064 can simply depend on the virtual package without having to
1065 specify all possible packages individually.
1069 All packages should use virtual package names where
1070 appropriate, and arrange to create new ones if necessary.
1071 They should not use virtual package names (except privately,
1072 amongst a cooperating group of packages) unless they have
1073 been agreed upon and appear in the list of virtual package
1074 names. (See also <ref id="virtual">)
1078 The latest version of the authoritative list of virtual
1079 package names can be found in the <tt>debian-policy</tt> package.
1080 It is also available from the Debian web mirrors at
1081 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1082 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
1083 and from the Debian archive mirrors at
1084 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
1085 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
1089 The procedure for updating the list is described in the preface
1096 <heading>Base system</heading>
1099 The <tt>base system</tt> is a minimum subset of the Debian
1100 GNU/Linux system that is installed before everything else
1101 on a new system. Thus, only very few packages are allowed
1102 to go into the <tt>base</tt> section to keep the required
1103 disk usage very small.
1107 Most of these packages will have the priority value
1108 <tt>required</tt> or at least <tt>important</tt>, and many
1109 of them will be tagged <tt>essential</tt> (see below).
1114 <heading>Essential packages</heading>
1117 Some packages are tagged <tt>essential</tt> for a system
1118 using the <tt>Essential</tt> control file field.
1119 The format of the <tt>Essential</tt> control field is
1120 described in <ref id="f-Essential">.
1124 Since these packages cannot be easily removed (one has to
1125 specify an extra <em>force option</em> to
1126 <prgn>dpkg</prgn> to do so), this flag must not be used
1127 unless absolutely necessary. A shared library package
1128 must not be tagged <tt>essential</tt>; dependencies will
1129 prevent its premature removal, and we need to be able to
1130 remove it when it has been superseded.
1134 Since dpkg will not prevent upgrading of other packages
1135 while an <tt>essential</tt> package is in an unconfigured
1136 state, all <tt>essential</tt> packages must supply all of
1137 their core functionality even when unconfigured. If the
1138 package cannot satisfy this requirement it must not be
1139 tagged as essential, and any packages depending on this
1140 package must instead have explicit dependency fields as
1145 You must not tag any packages <tt>essential</tt> before
1146 this has been discussed on the <tt>debian-devel</tt>
1147 mailing list and a consensus about doing that has been
1153 <heading>Tasks</heading>
1156 The Debian install process allows the user to choose from
1157 a number of common tasks which a Debian system can be used to
1158 perform. Selecting a task with <prgn>tasksel</prgn> causes
1159 a set of packages that are useful in performing that task to be
1164 This set of packages is all available packages which have the
1165 name of the selected task in the <tt>Task</tt> field of their
1166 control file. The format of this field is a list of tasks,
1167 separated by commas.
1171 You should not tag any packages as belonging to a task
1172 before this has been discussed on the
1173 <em>debian-devel</em> mailing list and a consensus about
1174 doing that has been reached.
1178 For third parties (and historical reasons), tasksel also
1179 supports constructing tasks based on <em>task
1180 packages</em>. These are packages whose names begin with
1181 <em>task-</em>. Task packages should not be included in the
1186 <sect id="maintscripts">
1187 <heading>Maintainer Scripts</heading>
1190 The package installation scripts should avoid producing
1191 output which it is unnecessary for the user to see and
1192 should rely on <prgn>dpkg</prgn> to stave off boredom on
1193 the part of a user installing many packages. This means,
1194 amongst other things, using the <tt>--quiet</tt> option on
1195 <prgn>install-info</prgn>.
1199 Errors which occur during the execution of an installation
1200 script must be checked and the installation must not
1201 continue after an error.
1205 Note that in general <ref id="scripts"> applies to package
1206 maintainer scripts, too.
1210 You should not use <prgn>dpkg-divert</prgn> on a file
1211 belonging to another package without consulting the
1212 maintainer of that package first.
1216 All packages which supply an instance of a common command
1217 name (or, in general, filename) should generally use
1218 <prgn>update-alternatives</prgn>, so that they may be
1219 installed together. If <prgn>update-alternatives</prgn>
1220 is not used, then each package must use
1221 <tt>Conflicts</tt> to ensure that other packages are
1222 de-installed. (In this case, it may be appropriate to
1223 specify a conflict against earlier versions of something
1224 that previously did not use
1225 <prgn>update-alternatives</prgn>; this is an exception to
1226 the usual rule that versioned conflicts should be
1230 <sect1 id="maintscriptprompt">
1231 <heading>Prompting in maintainer scripts</heading>
1233 Package maintainer scripts may prompt the user if
1234 necessary. Prompting should be done by communicating
1235 through a program, such as <prgn>debconf</prgn>, which
1236 conforms to the Debian Configuration management
1237 specification, version 2 or higher. Prompting the user by
1238 other means, such as by hand<footnote>
1239 From the Jargon file: by hand 2. By extension,
1240 writing code which does something in an explicit or
1241 low-level way for which a presupplied library
1242 (<em>debconf, in this instance</em>) routine ought
1243 to have been available.
1244 </footnote>, is now deprecated.
1248 The Debian Configuration management specification is included
1249 in the <file>debconf_specification</file> files in the
1250 <package>debian-policy</package> package.
1251 It is also available from the Debian web mirrors at
1252 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1253 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1254 and from the Debian archive mirrors at
1255 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1256 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1260 Packages which use the Debian Configuration management
1261 specification may contain an additional
1262 <prgn>config</prgn> script and a <tt>templates</tt>
1263 file in their control archive<footnote>
1264 The control.tar.gz inside the .deb.
1265 See <manref name="deb" section="5">.
1267 The <prgn>config</prgn> script might be run before the
1268 <prgn>preinst</prgn> script, and before the package is unpacked
1269 or any of its dependencies or pre-dependancies are satisfied.
1270 Therefore it must work using only the tools present in
1271 <em>essential</em> packages.<footnote>
1272 <package>Debconf</package> or another tool that
1273 implements the Debian Configuration management
1274 specification will also be installed, and any
1275 versioned dependencies on it will be satisfied
1276 before preconfiguration begins.
1281 Packages should try to minimize the amount of prompting
1282 they need to do, and they should ensure that the user
1283 will only ever be asked each question once. This means
1284 that packages should try to use appropriate shared
1285 configuration files (such as <file>/etc/papersize</file> and
1286 <file>/etc/news/server</file>), and shared
1287 <package>debconf</package> variables rather than each
1288 prompting for their own list of required pieces of
1293 It also means that an upgrade should not ask the same
1294 questions again, unless the user has used
1295 <tt>dpkg --purge</tt> to remove the package's configuration.
1296 The answers to configuration questions should be stored in an
1297 appropriate place in <file>/etc</file> so that the user can
1298 modify them, and how this has been done should be
1303 If a package has a vitally important piece of
1304 information to pass to the user (such as "don't run me
1305 as I am, you must edit the following configuration files
1306 first or you risk your system emitting badly-formatted
1307 messages"), it should display this in the
1308 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1309 prompt the user to hit return to acknowledge the
1310 message. Copyright messages do not count as vitally
1311 important (they belong in
1312 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1313 neither do instructions on how to use a program (these
1314 should be in on-line documentation, where all the users
1319 Any necessary prompting should almost always be confined
1320 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1321 script. If it is done in the <prgn>postinst</prgn>, it
1322 should be protected with a conditional so that
1323 unnecessary prompting doesn't happen if a package's
1324 installation fails and the <prgn>postinst</prgn> is
1325 called with <tt>abort-upgrade</tt>,
1326 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1336 <heading>Source packages</heading>
1338 <sect id="standardsversion">
1339 <heading>Standards conformance</heading>
1342 Source packages should specify the most recent version number
1343 of this policy document with which your package complied
1344 when it was last updated.
1348 This information may be used to file bug reports
1349 automatically if your package becomes too much out of date.
1353 The version is specified in the <tt>Standards-Version</tt>
1355 The format of the <tt>Standards-Version</tt> field is
1356 described in <ref id="f-Standards-Version">.
1360 You should regularly, and especially if your package has
1361 become out of date, check for the newest Policy Manual
1362 available and update your package, if necessary. When your
1363 package complies with the new standards you should update the
1364 <tt>Standards-Version</tt> source package field and
1365 release it.<footnote>
1366 See the file <file>upgrading-checklist</file> for
1367 information about policy which has changed between
1368 different versions of this document.
1374 <sect id="pkg-relations">
1375 <heading>Package relationships</heading>
1378 Source packages should specify which binary packages they
1379 require to be installed or not to be installed in order to
1380 build correctly. For example, if building a package
1381 requires a certain compiler, then the compiler should be
1382 specified as a build-time dependency.
1386 It is not necessary to explicitly specify build-time
1387 relationships on a minimal set of packages that are always
1388 needed to compile, link and put in a Debian package a
1389 standard "Hello World!" program written in C or C++. The
1390 required packages are called <em>build-essential</em>, and
1391 an informational list can be found in
1392 <file>/usr/share/doc/build-essential/list</file> (which is
1393 contained in the <tt>build-essential</tt>
1396 <list compact="compact">
1398 This allows maintaining the list separately
1399 from the policy documents (the list does not
1400 need the kind of control that the policy
1404 Having a separate package allows one to install
1405 the build-essential packages on a machine, as
1406 well as allowing other packages such as tasks to
1407 require installation of the build-essential
1408 packages using the depends relation.
1411 The separate package allows bug reports against
1412 the list to be categorized separately from
1413 the policy management process in the BTS.
1420 When specifying the set of build-time dependencies, one
1421 should list only those packages explicitly required by the
1422 build. It is not necessary to list packages which are
1423 required merely because some other package in the list of
1424 build-time dependencies depends on them.<footnote>
1425 The reason for this is that dependencies change, and
1426 you should list all those packages, and <em>only</em>
1427 those packages that <em>you</em> need directly. What
1428 others need is their business. For example, if you
1429 only link against <file>libimlib</file>, you will need to
1430 build-depend on <package>libimlib2-dev</package> but
1431 not against any <tt>libjpeg*</tt> packages, even
1432 though <tt>libimlib2-dev</tt> currently depends on
1433 them: installation of <package>libimlib2-dev</package>
1434 will automatically ensure that all of its run-time
1435 dependencies are satisfied.
1440 If build-time dependencies are specified, it must be
1441 possible to build the package and produce working binaries
1442 on a system with only essential and build-essential
1443 packages installed and also those required to satisfy the
1444 build-time relationships (including any implied
1445 relationships). In particular, this means that version
1446 clauses should be used rigorously in build-time
1447 relationships so that one cannot produce bad or
1448 inconsistently configured packages when the relationships
1449 are properly satisfied.
1453 <ref id="relationships"> explains the technical details.
1458 <heading>Changes to the upstream sources</heading>
1461 If changes to the source code are made that are not
1462 specific to the needs of the Debian system, they should be
1463 sent to the upstream authors in whatever form they prefer
1464 so as to be included in the upstream version of the
1469 If you need to configure the package differently for
1470 Debian or for Linux, and the upstream source doesn't
1471 provide a way to do so, you should add such configuration
1472 facilities (for example, a new <prgn>autoconf</prgn> test
1473 or <tt>#define</tt>) and send the patch to the upstream
1474 authors, with the default set to the way they originally
1475 had it. You can then easily override the default in your
1476 <file>debian/rules</file> or wherever is appropriate.
1480 You should make sure that the <prgn>configure</prgn> utility
1481 detects the correct architecture specification string
1482 (refer to <ref id="arch-spec"> for details).
1486 If you need to edit a <prgn>Makefile</prgn> where
1487 GNU-style <prgn>configure</prgn> scripts are used, you
1488 should edit the <file>.in</file> files rather than editing the
1489 <prgn>Makefile</prgn> directly. This allows the user to
1490 reconfigure the package if necessary. You should
1491 <em>not</em> configure the package and edit the generated
1492 <prgn>Makefile</prgn>! This makes it impossible for
1493 someone else to later reconfigure the package.
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>. This includes modifications
1505 made in the Debian package compared to the upstream one
1506 as well as other changes and updates to the package.
1508 Although there is nothing stopping an author who is also
1509 the Debian maintainer from using this changelog for all
1510 their changes, it will have to be renamed if the Debian
1511 and upstream maintainers become different people. In such
1512 a case, however, it might be better to maintain the package
1513 as a non-native package.
1518 Mistakes in changelogs are usually best rectified by making
1519 a new changelog entry rather than "rewriting history" by
1520 editing old changelog entries.
1524 The format of the <file>debian/changelog</file> allows the
1525 package building tools to discover which version of the package
1526 is being built and find out other release-specific information.
1530 That format is a series of entries like this:
1532 <example compact="compact">
1533 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1535 [optional blank line(s), stripped]
1537 * <var>change details</var>
1538 <var>more change details</var>
1540 [blank line(s), included in output of dpkg-parsechangelog]
1542 * <var>even more change details</var>
1544 [optional blank line(s), stripped]
1546 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1551 <var>package</var> and <var>version</var> are the source
1552 package name and version number.
1556 <var>distribution(s)</var> lists the distributions where
1557 this version should be installed when it is uploaded - it
1558 is copied to the <tt>Distribution</tt> field in the
1559 <file>.changes</file> file. See <ref id="f-Distribution">.
1563 <var>urgency</var> is the value for the <tt>Urgency</tt>
1564 field in the <file>.changes</file> file for the upload
1565 (see <ref id="f-Urgency">). It is not possible to specify
1566 an urgency containing commas; commas are used to separate
1567 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1568 <prgn>dpkg</prgn> changelog format (though there is
1569 currently only one useful <var>keyword</var>,
1570 <tt>urgency</tt>).<footnote>
1571 Recognised urgency values are <tt>low</tt>,
1572 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1573 They have an effect on how quickly a package will be
1574 considered for inclusion into the <tt>testing</tt>
1575 distribution, and give an indication of the importance
1576 of any fixes included in this upload.
1581 The change details may in fact be any series of lines
1582 starting with at least two spaces, but conventionally each
1583 change starts with an asterisk and a separating space and
1584 continuation lines are indented so as to bring them in
1585 line with the start of the text above. Blank lines may be
1586 used here to separate groups of changes, if desired.
1590 If this upload resolves bugs recorded in the Bug Tracking
1591 System (BTS), they may be automatically closed on the
1592 inclusion of this package into the Debian archive by
1593 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1594 in the change details.<footnote>
1595 To be precise, the string should match the following
1596 Perl regular expression:
1598 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1600 Then all of the bug numbers listed will be closed by the
1601 archive maintenance script (<prgn>katie</prgn>), or in
1602 the case of an NMU, marked as fixed.
1604 This information is conveyed via the <tt>Closes</tt> field
1605 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1609 The maintainer name and email address used in the changelog
1610 should be the details of the person uploading <em>this</em>
1611 version. They are <em>not</em> necessarily those of the
1612 usual package maintainer. The information here will be
1613 copied to the <tt>Changed-By</tt> field in the
1614 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1615 and then later used to send an acknowledgement when the
1616 upload has been installed.
1620 The <var>date</var> should be in RFC822 format<footnote>
1621 This is generated by the <prgn>822-date</prgn>
1623 </footnote>; it should include the time zone specified
1624 numerically, with the time zone name or abbreviation
1625 optionally present as a comment in parentheses.
1629 The first "title" line with the package name should start
1630 at the left hand margin; the "trailer" line with the
1631 maintainer and date details should be preceded by exactly
1632 one space. The maintainer details and the date must be
1633 separated by exactly two spaces.
1637 For more information on placement of the changelog files
1638 within binary packages, please see <ref id="changelogs">.
1641 <sect1><heading>Alternative changelog formats</heading>
1644 In non-experimental packages you must use a format for
1645 <file>debian/changelog</file> which is supported by the most
1646 recent released version of <prgn>dpkg</prgn>.
1650 It is possible to use a format different from the standard
1651 one by providing a changelog parser for the format you wish
1652 to use. The parser must have an API compatible with that
1653 expected by <prgn>dpkg-genchanges</prgn> and
1654 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1657 If there is general interest in the new format, you should
1658 contact the <package>dpkg</package> maintainer to have the
1659 parser script for it included in the <prgn>dpkg</prgn>
1660 package. (You will need to agree that the parser and its
1661 manpage may be distributed under the GNU GPL, just as the rest
1662 of <prgn>dpkg</prgn> is.)
1669 <heading>Error trapping in makefiles</heading>
1672 When <prgn>make</prgn> invokes a command in a makefile
1673 (including your package's upstream makefiles and
1674 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1675 means that <prgn>sh</prgn>'s usual bad error handling
1676 properties apply: if you include a miniature script as one
1677 of the commands in your makefile you'll find that if you
1678 don't do anything about it then errors are not detected
1679 and <prgn>make</prgn> will blithely continue after
1684 Every time you put more than one shell command (this
1685 includes using a loop) in a makefile command you
1686 must make sure that errors are trapped. For
1687 simple compound commands, such as changing directory and
1688 then running a program, using <tt>&&</tt> rather
1689 than semicolon as a command separator is sufficient. For
1690 more complex commands including most loops and
1691 conditionals you should include a separate <tt>set -e</tt>
1692 command at the start of every makefile command that's
1693 actually one of these miniature shell scripts.
1697 <sect id="timestamps">
1698 <heading>Time Stamps</heading>
1700 Maintainers should preserve the modification times of the
1701 upstream source files in a package, as far as is reasonably
1703 The rationale is that there is some information conveyed
1704 by knowing the age of the file, for example, you could
1705 recognize that some documentation is very old by looking
1706 at the modification time, so it would be nice if the
1707 modification time of the upstream source would be
1713 <sect id="restrictions">
1714 <heading>Restrictions on objects in source packages</heading>
1717 The source package may not contain any hard links<footnote>
1719 This is not currently detected when building source
1720 packages, but only when extracting
1724 Hard links may be permitted at some point in the
1725 future, but would require a fair amount of
1728 </footnote>, device special files, sockets or setuid or
1729 setgid files.<footnote>
1730 Setgid directories are allowed.
1735 <sect id="debianrules">
1736 <heading>Main building script: <file>debian/rules</file></heading>
1739 This file must be an executable makefile, and contains the
1740 package-specific recipes for compiling the package and
1741 building binary package(s) from the source.
1745 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1746 so that it can be invoked by saying its name rather than
1747 invoking <prgn>make</prgn> explicitly.
1751 Since an interactive <file>debian/rules</file> script makes it
1752 impossible to auto-compile that package and also makes it
1753 hard for other people to reproduce the same binary
1754 package, all <em>required targets</em> MUST be
1755 non-interactive. At a minimum, required targets are the
1756 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1757 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1758 <em>binary-indep</em>, and <em>build</em>. It also follows
1759 that any target that these targets depend on must also be
1764 The targets are as follows (required unless stated otherwise):
1766 <tag><tt>build</tt></tag>
1769 The <tt>build</tt> target should perform all the
1770 configuration and compilation of the package.
1771 If a package has an interactive pre-build
1772 configuration routine, the Debianized source package
1773 must either be built after this has taken place (so
1774 that the binary package can be built without rerunning
1775 the configuration) or the configuration routine
1776 modified to become non-interactive. (The latter is
1777 preferable if there are architecture-specific features
1778 detected by the configuration routine.)
1782 For some packages, notably ones where the same
1783 source tree is compiled in different ways to produce
1784 two binary packages, the <tt>build</tt> target
1785 does not make much sense. For these packages it is
1786 good enough to provide two (or more) targets
1787 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1788 for each of the ways of building the package, and a
1789 <tt>build</tt> target that does nothing. The
1790 <tt>binary</tt> target will have to build the
1791 package in each of the possible ways and make the
1792 binary package out of each.
1796 The <tt>build</tt> target must not do anything
1797 that might require root privilege.
1801 The <tt>build</tt> target may need to run the
1802 <tt>clean</tt> target first - see below.
1806 When a package has a configuration and build routine
1807 which takes a long time, or when the makefiles are
1808 poorly designed, or when <tt>build</tt> needs to
1809 run <tt>clean</tt> first, it is a good idea to
1810 <tt>touch build</tt> when the build process is
1811 complete. This will ensure that if <tt>debian/rules
1812 build</tt> is run again it will not rebuild the whole
1814 Another common way to do this is for <tt>build</tt>
1815 to depend on <prgn>build-stamp</prgn> and to do
1816 nothing else, and for the <prgn>build-stamp</prgn>
1817 target to do the building and to <tt>touch
1818 build-stamp</tt> on completion. This is
1819 especially useful if the build routine creates a
1820 file or directory called <tt>build</tt>; in such a
1821 case, <tt>build</tt> will need to be listed as
1822 a phony target (i.e., as a dependency of the
1823 <tt>.PHONY</tt> target). See the documentation of
1824 <prgn>make</prgn> for more information on phony
1830 <tag><tt>build-arch</tt> (optional),
1831 <tt>build-indep</tt> (optional)
1835 A package may also provide both of the targets
1836 <tt>build-arch</tt> and <tt>build-indep</tt>.
1837 The <tt>build-arch</tt> target, if provided, should
1838 perform all the configuration and compilation required
1839 for producing all architecture-dependant binary packages
1840 (those packages for which the body of the
1841 <tt>Architecture</tt> field in <tt>debian/control</tt>
1842 is not <tt>all</tt>).
1843 Similarly, the <tt>build-indep</tt> target, if
1844 provided, should perform all the configuration and
1845 compilation required for producing all
1846 architecture-independent binary packages
1847 (those packages for which the body of the
1848 <tt>Architecture</tt> field in <tt>debian/control</tt>
1850 The <tt>build</tt> target should depend on those of the
1851 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1852 are provided in the rules file.
1856 If one or both of the targets <tt>build-arch</tt> and
1857 <tt>build-indep</tt> are not provided, then invoking
1858 <file>debian/rules</file> with one of the not-provided
1859 targets as arguments should produce a exit status code
1860 of 2. Usually this is provided automatically by make
1861 if the target is missing.
1865 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1866 must not do anything that might require root privilege.
1870 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1871 <tt>binary-indep</tt>
1875 The <tt>binary</tt> target must be all that is
1876 necessary for the user to build the binary package(s)
1877 produced from this source package. It is
1878 split into two parts: <prgn>binary-arch</prgn> builds
1879 the binary packages which are specific to a particular
1880 architecture, and <tt>binary-indep</tt> builds
1881 those which are not.
1884 <tt>binary</tt> may be (and commonly is) a target with
1885 no commands which simply depends on
1886 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1889 Both <tt>binary-*</tt> targets should depend on the
1890 <tt>build</tt> target, or on the appropriate
1891 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1892 provided, so that the package is built if it has not
1893 been already. It should then create the relevant
1894 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1895 make their control files and <prgn>dpkg-deb</prgn> to
1896 build them and place them in the parent of the top
1901 Both the <tt>binary-arch</tt> and
1902 <tt>binary-indep</tt> targets <em>must</em> exist.
1903 If one of them has nothing to do (which will always be
1904 the case if the source generates only a single binary
1905 package, whether architecture-dependent or not), it
1906 must still exist and must always succeed.
1910 The <tt>binary</tt> targets must be invoked as
1912 The <prgn>fakeroot</prgn> package often allows one
1913 to build a package correctly even without being
1919 <tag><tt>clean</tt></tag>
1922 This must undo any effects that the <tt>build</tt>
1923 and <tt>binary</tt> targets may have had, except
1924 that it should leave alone any output files created in
1925 the parent directory by a run of a <tt>binary</tt>
1930 If a <tt>build</tt> file is touched at the end of
1931 the <tt>build</tt> target, as suggested above, it
1932 should be removed as the first action that
1933 <tt>clean</tt> performs, so that running
1934 <tt>build</tt> again after an interrupted
1935 <tt>clean</tt> doesn't think that everything is
1940 The <tt>clean</tt> target may need to be
1941 invoked as root if <tt>binary</tt> has been
1942 invoked since the last <tt>clean</tt>, or if
1943 <tt>build</tt> has been invoked as root (since
1944 <tt>build</tt> may create directories, for
1949 <tag><tt>get-orig-source</tt> (optional)</tag>
1952 This target fetches the most recent version of the
1953 original source package from a canonical archive site
1954 (via FTP or WWW, for example), does any necessary
1955 rearrangement to turn it into the original source
1956 tar file format described below, and leaves it in the
1961 This target may be invoked in any directory, and
1962 should take care to clean up any temporary files it
1967 This target is optional, but providing it if
1968 possible is a good idea.
1974 The <tt>build</tt>, <tt>binary</tt> and
1975 <tt>clean</tt> targets must be invoked with the current
1976 directory being the package's top-level directory.
1981 Additional targets may exist in <file>debian/rules</file>,
1982 either as published or undocumented interfaces or for the
1983 package's internal use.
1987 The architectures we build on and build for are determined
1988 by <prgn>make</prgn> variables using the utility
1989 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1990 You can determine the
1991 Debian architecture and the GNU style architecture
1992 specification string for the build machine (the machine type
1993 we are building on) as well as for the host machine (the
1994 machine type we are building for). Here is a list of
1995 supported <prgn>make</prgn> variables:
1996 <list compact="compact">
1998 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2001 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2002 specification string)
2005 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2006 <tt>DEB_*_GNU_TYPE</tt>)
2009 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2010 <tt>DEB_*_GNU_TYPE</tt>)
2012 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2013 the build machine or <tt>HOST</tt> for specification of the
2018 Backward compatibility can be provided in the rules file
2019 by setting the needed variables to suitable default
2020 values; please refer to the documentation of
2021 <prgn>dpkg-architecture</prgn> for details.
2025 It is important to understand that the <tt>DEB_*_ARCH</tt>
2026 string only determines which Debian architecture we are
2027 building on or for. It should not be used to get the CPU
2028 or system information; the GNU style variables should be
2033 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2034 <sect id="substvars">
2035 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2038 When <prgn>dpkg-gencontrol</prgn>,
2039 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2040 generate control files they perform variable substitutions
2041 on their output just before writing it. Variable
2042 substitutions have the form <tt>${<var>variable</var>}</tt>.
2043 The optional file <file>debian/substvars</file> contains
2044 variable substitutions to be used; variables can also be set
2045 directly from <file>debian/rules</file> using the <tt>-V</tt>
2046 option to the source packaging commands, and certain
2047 predefined variables are also available.
2051 The <file>debian/substvars</file> file is usually generated and
2052 modified dynamically by <file>debian/rules</file> targets, in
2053 which case it must be removed by the <tt>clean</tt> target.
2057 See <manref name="dpkg-source" section="1"> for full
2058 details about source variable substitutions, including the
2059 format of <file>debian/substvars</file>.</p>
2062 <sect id="debianfiles">
2063 <heading>Generated files list: <file>debian/files</file></heading>
2066 This file is not a permanent part of the source tree; it
2067 is used while building packages to record which files are
2068 being generated. <prgn>dpkg-genchanges</prgn> uses it
2069 when it generates a <file>.changes</file> file.
2073 It should not exist in a shipped source package, and so it
2074 (and any backup files or temporary files such as
2075 <file>files.new</file><footnote>
2076 <file>files.new</file> is used as a temporary file by
2077 <prgn>dpkg-gencontrol</prgn> and
2078 <prgn>dpkg-distaddfile</prgn> - they write a new
2079 version of <tt>files</tt> here before renaming it,
2080 to avoid leaving a corrupted copy if an error
2082 </footnote>) should be removed by the
2083 <tt>clean</tt> target. It may also be wise to
2084 ensure a fresh start by emptying or removing it at the
2085 start of the <tt>binary</tt> target.
2089 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2090 package, it adds an entry to <file>debian/files</file> for the
2091 <file>.deb</file> file that will be created when <tt>dpkg-deb
2092 --build</tt> is run for that binary package. So for most
2093 packages all that needs to be done with this file is to
2094 delete it in the <tt>clean</tt> target.
2098 If a package upload includes files besides the source
2099 package and any binary packages whose control files were
2100 made with <prgn>dpkg-gencontrol</prgn> then they should be
2101 placed in the parent of the package's top-level directory
2102 and <prgn>dpkg-distaddfile</prgn> should be called to add
2103 the file to the list in <file>debian/files</file>.</p>
2109 <chapt id="controlfields">
2110 <heading>Control files and their fields</heading>
2113 The package management system manipulates data represented in
2114 a common format, known as <em>control data</em>, stored in
2115 <em>control files</em>.
2116 Control files are used for source packages, binary packages and
2117 the <file>.changes</file> files which control the installation
2118 of uploaded files<footnote>
2119 <prgn>dpkg</prgn>'s internal databases are in a similar
2124 <sect id="controlsyntax">
2125 <heading>Syntax of control files</heading>
2128 A control file consists of one or more paragraphs of
2130 The paragraphs are also sometimes referred to as stanzas.
2132 The paragraphs are separated by blank lines. Some control
2133 files allow only one paragraph; others allow several, in
2134 which case each paragraph usually refers to a different
2135 package. (For example, in source packages, the first
2136 paragraph refers to the source package, and later paragraphs
2137 refer to binary packages generated from the source.)
2141 Each paragraph consists of a series of data fields; each
2142 field consists of the field name, followed by a colon and
2143 then the data/value associated with that field. It ends at
2144 the end of the line. Horizontal whitespace (spaces and
2145 tabs) may occur immediately before or after the value and is
2146 ignored there; it is conventional to put a single space
2147 after the colon. For example, a field might be:
2148 <example compact="compact">
2151 the field name is <tt>Package</tt> and the field value
2156 Some fields' values may span several lines; in this case
2157 each continuation line must start with a space or a tab.
2158 Any trailing spaces or tabs at the end of individual
2159 lines of a field value are ignored.
2163 Except where otherwise stated, only a single line of data is
2164 allowed and whitespace is not significant in a field body.
2165 Whitespace must not appear inside names (of packages,
2166 architectures, files or anything else) or version numbers,
2167 or between the characters of multi-character version
2172 Field names are not case-sensitive, but it is usual to
2173 capitalize the field names using mixed case as shown below.
2177 Blank lines, or lines consisting only of spaces and tabs,
2178 are not allowed within field values or between fields - that
2179 would mean a new paragraph.
2184 <sect id="sourcecontrolfiles">
2185 <heading>Source package control files -- <file>debian/control</file></heading>
2188 The <file>debian/control</file> file contains the most vital
2189 (and version-independent) information about the source package
2190 and about the binary packages it creates.
2194 The first paragraph of the control file contains information about
2195 the source package in general. The subsequent sets each describe a
2196 binary package that the source tree builds.
2200 The fields in the general paragraph (the first one, for the source
2203 <list compact="compact">
2204 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2205 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2206 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2207 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2208 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2209 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2214 The fields in the binary package paragraphs are:
2216 <list compact="compact">
2217 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2218 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2219 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2220 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2221 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2222 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2223 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2228 The syntax and semantics of the fields are described below.
2234 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2235 generate control files for binary packages (see below), by
2236 <prgn>dpkg-genchanges</prgn> to generate the
2237 <tt>.changes</tt> file to accompany the upload, and by
2238 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2239 source control file as part of a source archive.
2243 The fields here may contain variable references - their
2244 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2245 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2246 when they generate output control files.
2247 See <ref id="substvars"> for details.
2252 <sect id="binarycontrolfiles">
2253 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2256 The <file>DEBIAN/control</file> file contains the most vital
2257 (and version-dependent) information about a binary package.
2261 The fields in this file are:
2263 <list compact="compact">
2264 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2265 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2266 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2267 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2268 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2269 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2271 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2272 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2273 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2274 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2279 <sect id="debiansourcecontrolfiles">
2280 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2283 This file contains a series of fields, identified and
2284 separated just like the fields in the control file of
2285 a binary package. The fields are listed below; their
2286 syntax is described above, in <ref id="pkg-controlfields">.
2288 <list compact="compact">
2289 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2290 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2291 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2292 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2293 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2294 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2295 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2296 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2301 The source package control file is generated by
2302 <prgn>dpkg-source</prgn> when it builds the source
2303 archive, from other files in the source package,
2304 described above. When unpacking, it is checked against
2305 the files and directories in the other parts of the
2311 <sect id="debianchangesfiles">
2312 <heading>Debian changes files -- <file>.changes</file></heading>
2315 The .changes files are used by the Debian archive maintenance
2316 software to process updates to packages. They contain one
2317 paragraph which contains information from the
2318 <tt>debian/control</tt> file and other data about the
2319 source package gathered via <tt>debian/changelog</tt>
2320 and <tt>debian/rules</tt>.
2324 The fields in this file are:
2326 <list compact="compact">
2327 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2328 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2329 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2330 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2333 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2335 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2337 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2339 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2340 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2345 <sect id="controlfieldslist">
2346 <heading>List of fields</heading>
2348 <sect1 id="f-Source">
2349 <heading><tt>Source</tt></heading>
2352 This field identifies the source package name.
2356 In a main source control information, a <file>.changes</file>
2357 or a <file>.dsc</file> file this may contain only the name
2358 of the source package.
2362 In the control file of a binary package it may be followed
2363 by a version number in parentheses<footnote>
2364 It is customary to leave a space after the package name
2365 if a version number is specified.
2367 This version number may be omitted (and is, by
2368 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2369 the <tt>Version</tt> field of the binary package in
2370 question. The field itself may be omitted from a binary
2371 package control file when the source package has the same
2372 name and version as the binary package.
2376 <sect1 id="f-Maintainer">
2377 <heading><tt>Maintainer</tt></heading>
2380 The package maintainer's name and email address. The name
2381 should come first, then the email address inside angle
2382 brackets <tt><></tt> (in RFC822 format).
2386 If the maintainer's name contains a full stop then the
2387 whole field will not work directly as an email address due
2388 to a misfeature in the syntax specified in RFC822; a
2389 program using this field as an address must check for this
2390 and correct the problem if necessary (for example by
2391 putting the name in round brackets and moving it to the
2392 end, and bringing the email address forward).
2396 <sect1 id="f-Changed-By">
2397 <heading><tt>Changed-By</tt></heading>
2400 The name and email address of the person who changed the
2401 said package. Usually the name of the maintainer.
2402 All the rules for the Maintainer field apply here, too.
2406 <sect1 id="f-Section">
2407 <heading><tt>Section</tt></heading>
2410 This field specifies an application area into which the package
2411 has been classified. See <ref id="subsections">.
2415 When it appears in the <file>debian/control</file> file,
2416 it gives the value for the subfield of the same name in
2417 the <tt>Files</tt> field of the <file>.changes</file> file.
2418 It also gives the default for the same field in the binary
2423 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2424 field in the control file of a binary package - use the
2425 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2429 <sect1 id="f-Priority">
2430 <heading><tt>Priority</tt></heading>
2433 This field represents how important that it is that the user
2434 have the package installed. See <ref id="priorities">.
2438 When it appears in the <file>debian/control</file> file,
2439 it gives the value for the subfield of the same name in
2440 the <tt>Files</tt> field of the <file>.changes</file> file.
2441 It also gives the default for the same field in the binary
2446 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2447 field in the control file of a binary package - use the
2448 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2452 <sect1 id="f-Package">
2453 <heading><tt>Package</tt></heading>
2456 The name of the binary package.
2460 Package names must consist only of lower case letters
2461 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2462 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2463 They must be at least two characters long and must start
2464 with an alphanumeric character.
2468 <sect1 id="f-Architecture">
2469 <heading><tt>Architecture</tt></heading>
2472 This is the architecture string; it is a single word for
2473 the Debian architecture. The special value <tt>all</tt>
2474 indicates that the package is architecture-independent.
2478 In the main <file>debian/control</file> file in the source
2479 package, or in the source package control file
2480 <file>.dsc</file>, a list of architectures (separated by
2481 spaces) is also allowed, as is the special value
2482 <tt>any</tt>. A list indicates that the source will build
2483 an architecture-dependent package, and will only work
2484 correctly on the listed architectures. <tt>any</tt>
2485 indicates that though the source package isn't dependent
2486 on any particular architecture and should compile fine on
2487 any one, the binary package(s) produced are not
2488 architecture-independent but will instead be specific to
2489 whatever the current build architecture is.
2493 In a <file>.changes</file> file the <tt>Architecture</tt>
2494 field lists the architecture(s) of the package(s)
2495 currently being uploaded. This will be a list; if the
2496 source for the package is being uploaded too the special
2497 entry <tt>source</tt> is also present.
2501 See <ref id="debianrules"> for information how to get the
2502 architecture for the build process.
2506 <sect1 id="f-Essential">
2507 <heading><tt>Essential</tt></heading>
2510 This is a boolean field which may occur only in the
2511 control file of a binary package or in a per-package fields
2512 paragraph of a main source control data file.
2516 If set to <tt>yes</tt> then the package management system
2517 will refuse to remove the package (upgrading and replacing
2518 it is still possible). The other possible value is <tt>no</tt>,
2519 which is the same as not having the field at all.
2524 <heading>Package interrelationship fields:
2525 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2526 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2527 <tt>Provides</tt>, <tt>Replaces</tt>
2531 These fields describe the package's relationships with
2532 other packages. Their syntax and semantics are described
2533 in <ref id="relationships">.</p>
2536 <sect1 id="f-Standards-Version">
2537 <heading><tt>Standards-Version</tt></heading>
2540 The most recent version of the standards (the policy
2541 manual and associated texts) with which the package
2546 The version number has four components: major and minor
2547 version number and major and minor patch level. When the
2548 standards change in a way that requires every package to
2549 change the major number will be changed. Significant
2550 changes that will require work in many packages will be
2551 signaled by a change to the minor number. The major patch
2552 level will be changed for any change to the meaning of the
2553 standards, however small; the minor patch level will be
2554 changed when only cosmetic, typographical or other edits
2555 are made which neither change the meaning of the document
2556 nor affect the contents of packages.
2560 Thus only the first three components of the policy version
2561 are significant in the <em>Standards-Version</em> control
2562 field, and so either these three components or the all
2563 four components may be specified.<footnote>
2564 In the past, people specified the full version number
2565 in the Standards-Version field, for example "2.3.0.0".
2566 Since minor patch-level changes don't introduce new
2567 policy, it was thought it would be better to relax
2568 policy and only require the first 3 components to be
2569 specified, in this example "2.3.0". All four
2570 components may still be used if someone wishes to do so.
2576 <sect1 id="f-Version">
2577 <heading><tt>Version</tt></heading>
2580 The version number of a package. The format is:
2581 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2585 The three components here are:
2587 <tag><var>epoch</var></tag>
2590 This is a single (generally small) unsigned integer. It
2591 may be omitted, in which case zero is assumed. If it is
2592 omitted then the <var>upstream_version</var> may not
2597 It is provided to allow mistakes in the version numbers
2598 of older versions of a package, and also a package's
2599 previous version numbering schemes, to be left behind.
2603 <tag><var>upstream_version</var></tag>
2606 This is the main part of the version number. It is
2607 usually the version number of the original ("upstream")
2608 package from which the <file>.deb</file> file has been made,
2609 if this is applicable. Usually this will be in the same
2610 format as that specified by the upstream author(s);
2611 however, it may need to be reformatted to fit into the
2612 package management system's format and comparison
2617 The comparison behavior of the package management system
2618 with respect to the <var>upstream_version</var> is
2619 described below. The <var>upstream_version</var>
2620 portion of the version number is mandatory.
2624 The <var>upstream_version</var> may contain only
2625 alphanumerics<footnote>
2626 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2628 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2629 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2630 start with a digit. If there is no
2631 <var>debian_revision</var> then hyphens are not allowed;
2632 if there is no <var>epoch</var> then colons are not
2637 <tag><var>debian_revision</var></tag>
2640 This part of the version number specifies the version of
2641 the Debian package based on the upstream version. It
2642 may contain only alphanumerics and the characters
2643 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2644 compared in the same way as the
2645 <var>upstream_version</var> is.
2649 It is optional; if it isn't present then the
2650 <var>upstream_version</var> may not contain a hyphen.
2651 This format represents the case where a piece of
2652 software was written specifically to be turned into a
2653 Debian package, and so there is only one "debianization"
2654 of it and therefore no revision indication is required.
2658 It is conventional to restart the
2659 <var>debian_revision</var> at <tt>1</tt> each time the
2660 <var>upstream_version</var> is increased.
2664 The package management system will break the version
2665 number apart at the last hyphen in the string (if there
2666 is one) to determine the <var>upstream_version</var> and
2667 <var>debian_revision</var>. The absence of a
2668 <var>debian_revision</var> compares earlier than the
2669 presence of one (but note that the
2670 <var>debian_revision</var> is the least significant part
2671 of the version number).
2678 The <var>upstream_version</var> and <var>debian_revision</var>
2679 parts are compared by the package management system using the
2684 The strings are compared from left to right.
2688 First the initial part of each string consisting entirely of
2689 non-digit characters is determined. These two parts (one of
2690 which may be empty) are compared lexically. If a difference
2691 is found it is returned. The lexical comparison is a
2692 comparison of ASCII values modified so that all the letters
2693 sort earlier than all the non-letters.
2697 Then the initial part of the remainder of each string which
2698 consists entirely of digit characters is determined. The
2699 numerical values of these two parts are compared, and any
2700 difference found is returned as the result of the comparison.
2701 For these purposes an empty string (which can only occur at
2702 the end of one or both version strings being compared) counts
2707 These two steps (comparing and removing initial non-digit
2708 strings and initial digit strings) are repeated until a
2709 difference is found or both strings are exhausted.
2713 Note that the purpose of epochs is to allow us to leave behind
2714 mistakes in version numbering, and to cope with situations
2715 where the version numbering scheme changes. It is
2716 <em>not</em> intended to cope with version numbers containing
2717 strings of letters which the package management system cannot
2718 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2719 silly orderings (the author of this manual has heard of a
2720 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2721 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2722 <tt>2</tt> and so forth).
2726 <sect1 id="f-Description">
2727 <heading><tt>Description</tt></heading>
2730 In a source or binary control file, the <tt>Description</tt>
2731 field contains a description of the binary package, consisting
2732 of two parts, the synopsis or the short description, and the
2733 long description. The field's format is as follows:
2738 Description: <single line synopsis>
2739 <extended description over several lines>
2744 The lines in the extended description can have these formats:
2750 Those starting with a single space are part of a paragraph.
2751 Successive lines of this form will be word-wrapped when
2752 displayed. The leading space will usually be stripped off.
2756 Those starting with two or more spaces. These will be
2757 displayed verbatim. If the display cannot be panned
2758 horizontally, the displaying program will linewrap them "hard"
2759 (i.e., without taking account of word breaks). If it can they
2760 will be allowed to trail off to the right. None, one or two
2761 initial spaces may be deleted, but the number of spaces
2762 deleted from each line will be the same (so that you can have
2763 indenting work correctly, for example).
2767 Those containing a single space followed by a single full stop
2768 character. These are rendered as blank lines. This is the
2769 <em>only</em> way to get a blank line<footnote>
2770 Completely empty lines will not be rendered as blank lines.
2771 Instead, they will cause the parser to think you're starting
2772 a whole new record in the control file, and will therefore
2773 likely abort with an error.
2778 Those containing a space, a full stop and some more characters.
2779 These are for future expansion. Do not use them.
2785 Do not use tab characters. Their effect is not predictable.
2789 See <ref id="descriptions"> for further information on this.
2793 In a <file>.changes</file> file, the <tt>Description</tt> field
2794 contains a summary of the descriptions for the packages being
2799 The part of the field before the first newline is empty;
2800 thereafter each line has the name of a binary package and
2801 the summary description line from that binary package.
2802 Each line is indented by one space.
2807 <sect1 id="f-Distribution">
2808 <heading><tt>Distribution</tt></heading>
2811 In a <file>.changes</file> file or parsed changelog output
2812 this contains the (space-separated) name(s) of the
2813 distribution(s) where this version of the package should
2814 be installed. Valid distributions are determined by the
2815 archive maintainers.<footnote>
2816 Current distribution names are:
2817 <taglist compact="compact">
2818 <tag><em>stable</em></tag>
2820 This is the current "released" version of Debian
2821 GNU/Linux. Once the distribution is
2822 <em>stable</em> only security fixes and other
2823 major bug fixes are allowed. When changes are
2824 made to this distribution, the release number is
2825 increased (for example: 2.2r1 becomes 2.2r2 then
2829 <tag><em>unstable</em></tag>
2831 This distribution value refers to the
2832 <em>developmental</em> part of the Debian
2833 distribution tree. New packages, new upstream
2834 versions of packages and bug fixes go into the
2835 <em>unstable</em> directory tree. Download from
2836 this distribution at your own risk.
2839 <tag><em>testing</em></tag>
2841 This distribution value refers to the
2842 <em>testing</em> part of the Debian distribution
2843 tree. It receives its packages from the
2844 unstable distribution after a short time lag to
2845 ensure that there are no major issues with the
2846 unstable packages. It is less prone to breakage
2847 than unstable, but still risky. It is not
2848 possible to upload packages directly to
2852 <tag><em>frozen</em></tag>
2854 From time to time, the <em>testing</em>
2855 distribution enters a state of "code-freeze" in
2856 anticipation of release as a <em>stable</em>
2857 version. During this period of testing only
2858 fixes for existing or newly-discovered bugs will
2859 be allowed. The exact details of this stage are
2860 determined by the Release Manager.
2863 <tag><em>experimental</em></tag>
2865 The packages with this distribution value are
2866 deemed by their maintainers to be high
2867 risk. Oftentimes they represent early beta or
2868 developmental packages from various sources that
2869 the maintainers want people to try, but are not
2870 ready to be a part of the other parts of the
2871 Debian distribution tree. Download at your own
2877 You should list <em>all</em> distributions that the
2878 package should be installed into.
2882 More information is available in the Debian Developer's
2883 Reference, section "The Debian archive".
2890 <heading><tt>Date</tt></heading>
2893 This field includes the date the package was built or last edited.
2897 The value of this field is usually extracted from the
2898 <file>debian/changelog</file> file - see
2899 <ref id="dpkgchangelog">).
2903 <sect1 id="f-Format">
2904 <heading><tt>Format</tt></heading>
2907 This field specifies a format revision for the file.
2908 The most current format described in the Policy Manual
2909 is version <strong>1.5</strong>. The syntax of the
2910 format value is the same as that of a package version
2911 number except that no epoch or Debian revision is allowed
2912 - see <ref id="f-Version">.
2916 <sect1 id="f-Urgency">
2917 <heading><tt>Urgency</tt></heading>
2920 This is a description of how important it is to upgrade to
2921 this version from previous ones. It consists of a single
2922 keyword usually taking one of the values <tt>low</tt>,
2923 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2924 followed by an optional commentary (separated by a space)
2925 which is usually in parentheses. For example:
2928 Urgency: low (HIGH for users of diversions)
2934 The value of this field is usually extracted from the
2935 <file>debian/changelog</file> file - see
2936 <ref id="dpkgchangelog">.
2940 <sect1 id="f-Changes">
2941 <heading><tt>Changes</tt></heading>
2944 This field contains the human-readable changes data, describing
2945 the differences between the last version and the current one.
2949 There should be nothing in this field before the first
2950 newline; all the subsequent lines must be indented by at
2951 least one space; blank lines must be represented by a line
2952 consiting only of a space and a full stop.
2956 The value of this field is usually extracted from the
2957 <file>debian/changelog</file> file - see
2958 <ref id="dpkgchangelog">).
2962 Each version's change information should be preceded by a
2963 "title" line giving at least the version, distribution(s)
2964 and urgency, in a human-readable way.
2968 If data from several versions is being returned the entry
2969 for the most recent version should be returned first, and
2970 entries should be separated by the representation of a
2971 blank line (the "title" line may also be followed by the
2972 representation of blank line).
2976 <sect1 id="f-Binary">
2977 <heading><tt>Binary</tt></heading>
2980 This field is a list of binary packages.
2984 When it appears in the <file>.dsc</file> file it is the list
2985 of binary packages which a source package can produce. It
2986 does not necessarily produce all of these binary packages
2987 for every architecture. The source control file doesn't
2988 contain details of which architectures are appropriate for
2989 which of the binary packages.
2993 When it appears in a <file>.changes</file> file it lists the
2994 names of the binary packages actually being uploaded.
2998 The syntax is a list of binary packages separated by
3000 A space after each comma is conventional.
3001 </footnote>. Currently the packages must be separated using
3002 only spaces in the <file>.changes</file> file.
3006 <sect1 id="f-Installed-Size">
3007 <heading><tt>Installed-Size</tt></heading>
3010 This field appears in the control files of binary
3011 packages, and in the <file>Packages</file> files. It gives
3012 the total amount of disk space required to install the
3017 The disk space is represented in kilobytes as a simple
3022 <sect1 id="f-Files">
3023 <heading><tt>Files</tt></heading>
3026 This field contains a list of files with information about
3027 each one. The exact information and syntax varies with
3028 the context. In all cases the part of the field
3029 contents on the same line as the field name is empty. The
3030 remainder of the field is one line per file, each line
3031 being indented by one space and containing a number of
3032 sub-fields separated by spaces.
3036 In the <file>.dsc</file> file, each line contains the MD5
3037 checksum, size and filename of the tar file and (if applicable)
3038 diff file which make up the remainder of the source
3040 That is, the parts which are not the <tt>.dsc</tt>.
3042 The exact forms of the filenames are described
3043 in <ref id="pkg-sourcearchives">.
3047 In the <file>.changes</file> file this contains one line per
3048 file being uploaded. Each line contains the MD5 checksum,
3049 size, section and priority and the filename.
3050 The <qref id="f-Section">section</qref>
3051 and <qref id="f-Priority">priority</qref>
3052 are the values of the corresponding fields in
3053 the main source control file. If no section or priority is
3054 specified then <tt>-</tt> should be used, though section
3055 and priority values must be specified for new packages to
3056 be installed properly.
3060 The special value <tt>byhand</tt> for the section in a
3061 <tt>.changes</tt> file indicates that the file in question
3062 is not an ordinary package file and must by installed by
3063 hand by the distribution maintainers. If the section is
3064 <tt>byhand</tt> the priority should be <tt>-</tt>.
3068 If a new Debian revision of a package is being shipped and
3069 no new original source archive is being distributed the
3070 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3071 entry for the original source archive
3072 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3073 but the <file>.changes</file> file should leave it out. In
3074 this case the original source archive on the distribution
3075 site must match exactly, byte-for-byte, the original
3076 source archive which was used to generate the
3077 <file>.dsc</file> file and diff which are being uploaded.</p>
3080 <sect1 id="f-Closes">
3081 <heading><tt>Closes</tt></heading>
3084 A space-separated list of bug report numbers that the upload
3085 governed by the .changes file closes.
3092 <heading>User-defined fields</heading>
3095 Additional user-defined fields may be added to the
3096 source package control file. Such fields will be
3097 ignored, and not copied to (for example) binary or
3098 source package control files or upload control files.
3102 If you wish to add additional unsupported fields to
3103 these output files you should use the mechanism
3108 Fields in the main source control information file with
3109 names starting <tt>X</tt>, followed by one or more of
3110 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3111 be copied to the output files. Only the part of the
3112 field name after the hyphen will be used in the output
3113 file. Where the letter <tt>B</tt> is used the field
3114 will appear in binary package control files, where the
3115 letter <tt>S</tt> is used in source package control
3116 files and where <tt>C</tt> is used in upload control
3117 (<tt>.changes</tt>) files.
3121 For example, if the main source information control file
3124 XBS-Comment: I stand between the candle and the star.
3126 then the binary and source package control files will contain the
3129 Comment: I stand between the candle and the star.
3138 <chapt id="maintainerscripts">
3139 <heading>Package maintainer scripts and installation procedure</heading>
3142 <heading>Introduction to package maintainer scripts</heading>
3145 It is possible to supply scripts as part of a package which
3146 the package management system will run for you when your
3147 package is installed, upgraded or removed.
3151 These scripts are the files <prgn>preinst</prgn>,
3152 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3153 control area of the package. They must be proper executable
3154 files; if they are scripts (which is recommended), they must
3155 start with the usual <tt>#!</tt> convention. They should be
3156 readable and executable by anyone, and not world-writable.
3160 The package management system looks at the exit status from
3161 these scripts. It is important that they exit with a
3162 non-zero status if there is an error, so that the package
3163 management system can stop its processing. For shell
3164 scripts this means that you <em>almost always</em> need to
3165 use <tt>set -e</tt> (this is usually true when writing shell
3166 scripts, in fact). It is also important, of course, that
3167 they don't exit with a non-zero status if everything went
3172 When a package is upgraded a combination of the scripts from
3173 the old and new packages is called during the upgrade
3174 procedure. If your scripts are going to be at all
3175 complicated you need to be aware of this, and may need to
3176 check the arguments to your scripts.
3180 Broadly speaking the <prgn>preinst</prgn> is called before
3181 (a particular version of) a package is installed, and the
3182 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3183 before (a version of) a package is removed and the
3184 <prgn>postrm</prgn> afterwards.
3188 Programs called from maintainer scripts should not normally
3189 have a path prepended to them. Before installation is
3190 started, the package management system checks to see if the
3191 programs <prgn>ldconfig</prgn>,
3192 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3193 and <prgn>update-rc.d</prgn> can be found via the
3194 <tt>PATH</tt> environment variable. Those programs, and any
3195 other program that one would expect to be on the
3196 <tt>PATH</tt>, should thus be invoked without an absolute
3197 pathname. Maintainer scripts should also not reset the
3198 <tt>PATH</tt>, though they might choose to modify it by
3199 prepending or appending package-specific directories. These
3200 considerations really apply to all shell scripts.</p>
3203 <sect id="idempotency">
3204 <heading>Maintainer scripts Idempotency</heading>
3207 It is necessary for the error recovery procedures that the
3208 scripts be idempotent. This means that if it is run
3209 successfully, and then it is called again, it doesn't bomb
3210 out or cause any harm, but just ensures that everything is
3211 the way it ought to be. If the first call failed, or
3212 aborted half way through for some reason, the second call
3213 should merely do the things that were left undone the first
3214 time, if any, and exit with a success status if everything
3216 This is so that if an error occurs, the user interrupts
3217 <prgn>dpkg</prgn> or some other unforeseen circumstance
3218 happens you don't leave the user with a badly-broken
3219 package when <prgn>dpkg</prgn> attempts to repeat the
3225 <sect id="controllingterminal">
3226 <heading>Controlling terminal for maintainer scripts</heading>
3229 The maintainer scripts are guaranteed to run with a
3230 controlling terminal and can interact with the user.
3231 If they need to prompt for passwords, do full-screen
3232 interaction or something similar you should do these
3233 things to and from <file>/dev/tty</file>, since
3234 <prgn>dpkg</prgn> will at some point redirect scripts'
3235 standard input and output so that it can log the
3236 installation process. Likewise, because these scripts
3237 may be executed with standard output redirected into a
3238 pipe for logging purposes, Perl scripts should set
3239 unbuffered output by setting <tt>$|=1</tt> so that the
3240 output is printed immediately rather than being
3245 Each script should return a zero exit status for
3246 success, or a nonzero one for failure.
3250 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3255 <list compact="compact">
3257 <var>new-preinst</var> <tt>install</tt>
3260 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3263 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3266 <var>old-preinst</var> <tt>abort-upgrade</tt>
3267 <var>new-version</var>
3272 <list compact="compact">
3274 <var>postinst</var> <tt>configure</tt>
3275 <var>most-recently-configured-version</var>
3278 <var>old-postinst</var> <tt>abort-upgrade</tt>
3279 <var>new-version</var>
3282 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3283 <tt>in-favour</tt> <var>package</var>
3284 <var>new-version</var>
3287 <var>deconfigured's-postinst</var>
3288 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3289 <var>failed-install-package</var> <var>version</var>
3290 <tt>removing</tt> <var>conflicting-package</var>
3296 <list compact="compact">
3298 <var>prerm</var> <tt>remove</tt>
3301 <var>old-prerm</var> <tt>upgrade</tt>
3302 <var>new-version</var>
3305 <var>new-prerm</var> <tt>failed-upgrade</tt>
3306 <var>old-version</var>
3309 <var>conflictor's-prerm</var> <tt>remove</tt>
3310 <tt>in-favour</tt> <var>package</var>
3311 <var>new-version</var>
3314 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3315 <tt>in-favour</tt> <var>package-being-installed</var>
3316 <var>version</var> <tt>removing</tt>
3317 <var>conflicting-package</var>
3323 <list compact="compact">
3325 <var>postrm</var> <tt>remove</tt>
3328 <var>postrm</var> <tt>purge</tt>
3331 <var>old-postrm</var> <tt>upgrade</tt>
3332 <var>new-version</var>
3335 <var>new-postrm</var> <tt>failed-upgrade</tt>
3336 <var>old-version</var>
3339 <var>new-postrm</var> <tt>abort-install</tt>
3342 <var>new-postrm</var> <tt>abort-install</tt>
3343 <var>old-version</var>
3346 <var>new-postrm</var> <tt>abort-upgrade</tt>
3347 <var>old-version</var>
3350 <var>disappearer's-postrm</var> <tt>disappear</tt>
3351 <var>overwriter</var>
3352 <var>overwriter-version</var>
3358 <sect id="unpackphase">
3359 <heading>Details of unpack phase of installation or upgrade</heading>
3362 The procedure on installation/upgrade/overwrite/disappear
3363 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3364 stage of <tt>dpkg --install</tt>) is as follows. In each
3365 case, if a major error occurs (unless listed below) the
3366 actions are, in general, run backwards - this means that the
3367 maintainer scripts are run with different arguments in
3368 reverse order. These are the "error unwind" calls listed
3375 If a version of the package is already installed, call
3376 <example compact="compact">
3377 <var>old-prerm</var> upgrade <var>new-version</var>
3381 If the script runs but exits with a non-zero
3382 exit status, <prgn>dpkg</prgn> will attempt:
3383 <example compact="compact">
3384 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3386 Error unwind, for both the above cases:
3387 <example compact="compact">
3388 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3395 If a "conflicting" package is being removed at the same time:
3398 If any packages depended on that conflicting
3399 package and <tt>--auto-deconfigure</tt> is
3400 specified, call, for each such package:
3401 <example compact="compact">
3402 <var>deconfigured's-prerm</var> deconfigure \
3403 in-favour <var>package-being-installed</var> <var>version</var> \
3404 removing <var>conflicting-package</var> <var>version</var>
3407 <example compact="compact">
3408 <var>deconfigured's-postinst</var> abort-deconfigure \
3409 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3410 removing <var>conflicting-package</var> <var>version</var>
3412 The deconfigured packages are marked as
3413 requiring configuration, so that if
3414 <tt>--install</tt> is used they will be
3415 configured again if possible.
3418 To prepare for removal of the conflicting package, call:
3419 <example compact="compact">
3420 <var>conflictor's-prerm</var> remove \
3421 in-favour <var>package</var> <var>new-version</var>
3424 <example compact="compact">
3425 <var>conflictor's-postinst</var> abort-remove \
3426 in-favour <var>package</var> <var>new-version</var>
3435 If the package is being upgraded, call:
3436 <example compact="compact">
3437 <var>new-preinst</var> upgrade <var>old-version</var>
3441 Otherwise, if the package had some configuration
3442 files from a previous version installed (i.e., it
3443 is in the "configuration files only" state):
3444 <example compact="compact">
3445 <var>new-preinst</var> install <var>old-version</var>
3449 Otherwise (i.e., the package was completely purged):
3450 <example compact="compact">
3451 <var>new-preinst</var> install
3453 Error unwind actions, respectively:
3454 <example compact="compact">
3455 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3456 <var>new-postrm</var> abort-install <var>old-version</var>
3457 <var>new-postrm</var> abort-install
3465 The new package's files are unpacked, overwriting any
3466 that may be on the system already, for example any
3467 from the old version of the same package or from
3468 another package. Backups of the old files are kept
3469 temporarily, and if anything goes wrong the package
3470 management system will attempt to put them back as
3471 part of the error unwind.
3475 It is an error for a package to contain files which
3476 are on the system in another package, unless
3477 <tt>Replaces</tt> is used (see <ref id="replaces">).
3479 The following paragraph is not currently the case:
3480 Currently the <tt>- - force-overwrite</tt> flag is
3481 enabled, downgrading it to a warning, but this may not
3487 It is a more serious error for a package to contain a
3488 plain file or other kind of non-directory where another
3489 package has a directory (again, unless
3490 <tt>Replaces</tt> is used). This error can be
3491 overridden if desired using
3492 <tt>--force-overwrite-dir</tt>, but this is not
3497 Packages which overwrite each other's files produce
3498 behavior which, though deterministic, is hard for the
3499 system administrator to understand. It can easily
3500 lead to "missing" programs if, for example, a package
3501 is installed which overwrites a file from another
3502 package, and is then removed again.<footnote>
3503 Part of the problem is due to what is arguably a
3504 bug in <prgn>dpkg</prgn>.
3509 A directory will never be replaced by a symbolic link
3510 to a directory or vice versa; instead, the existing
3511 state (symlink or not) will be left alone and
3512 <prgn>dpkg</prgn> will follow the symlink if there is
3521 If the package is being upgraded, call
3522 <example compact="compact">
3523 <var>old-postrm</var> upgrade <var>new-version</var>
3527 If this fails, <prgn>dpkg</prgn> will attempt:
3528 <example compact="compact">
3529 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3531 Error unwind, for both cases:
3532 <example compact="compact">
3533 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3540 This is the point of no return - if
3541 <prgn>dpkg</prgn> gets this far, it won't back off
3542 past this point if an error occurs. This will
3543 leave the package in a fairly bad state, which
3544 will require a successful re-installation to clear
3545 up, but it's when <prgn>dpkg</prgn> starts doing
3546 things that are irreversible.
3551 Any files which were in the old version of the package
3552 but not in the new are removed.
3556 The new file list replaces the old.
3560 The new maintainer scripts replace the old.
3564 Any packages all of whose files have been overwritten
3565 during the installation, and which aren't required for
3566 dependencies, are considered to have been removed.
3567 For each such package
3570 <prgn>dpkg</prgn> calls:
3571 <example compact="compact">
3572 <var>disappearer's-postrm</var> disappear \
3573 <var>overwriter</var> <var>overwriter-version</var>
3577 The package's maintainer scripts are removed.
3580 It is noted in the status database as being in a
3581 sane state, namely not installed (any conffiles
3582 it may have are ignored, rather than being
3583 removed by <prgn>dpkg</prgn>). Note that
3584 disappearing packages do not have their prerm
3585 called, because <prgn>dpkg</prgn> doesn't know
3586 in advance that the package is going to
3593 Any files in the package we're unpacking that are also
3594 listed in the file lists of other packages are removed
3595 from those lists. (This will lobotomize the file list
3596 of the "conflicting" package if there is one.)
3600 The backup files made during installation, above, are
3606 The new package's status is now sane, and recorded as
3611 Here is another point of no return - if the
3612 conflicting package's removal fails we do not unwind
3613 the rest of the installation; the conflicting package
3614 is left in a half-removed limbo.
3619 If there was a conflicting package we go and do the
3620 removal actions (described below), starting with the
3621 removal of the conflicting package's files (any that
3622 are also in the package being installed have already
3623 been removed from the conflicting package's file list,
3624 and so do not get removed now).
3630 <sect id="configdetails"><heading>Details of configuration</heading>
3633 When we configure a package (this happens with <tt>dpkg
3634 --install</tt> and <tt>dpkg --configure</tt>), we first
3635 update any <tt>conffile</tt>s and then call:
3636 <example compact="compact">
3637 <var>postinst</var> configure <var>most-recently-configured-version</var>
3642 No attempt is made to unwind after errors during
3647 If there is no most recently configured version
3648 <prgn>dpkg</prgn> will pass a null argument.
3651 Historical note: Truly ancient (pre-1997) versions of
3652 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3653 (including the angle brackets) in this case. Even older
3654 ones did not pass a second argument at all, under any
3655 circumstance. Note that upgrades using such an old dpkg
3656 version are unlikely to work for other reasons, even if
3657 this old argument behavior is handled by your postinst script.
3663 <sect id="removedetails"><heading>Details of removal and/or
3664 configuration purging</heading>
3669 <example compact="compact">
3670 <var>prerm</var> remove
3674 The package's files are removed (except <tt>conffile</tt>s).
3677 <example compact="compact">
3678 <var>postrm</var> remove
3683 All the maintainer scripts except the <prgn>postrm</prgn>
3688 If we aren't purging the package we stop here. Note
3689 that packages which have no <prgn>postrm</prgn> and no
3690 <tt>conffile</tt>s are automatically purged when
3691 removed, as there is no difference except for the
3692 <prgn>dpkg</prgn> status.
3696 The <tt>conffile</tt>s and any backup files
3697 (<tt>~</tt>-files, <tt>#*#</tt> files,
3698 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3702 <example compact="compact">
3703 <var>postrm</var> purge
3707 The package's file list is removed.
3711 If there are problems during this process, we call
3712 <example compact="compact">postinst
3713 abort-remove</example>. No other attempt is made to unwind
3714 after errors during removal.
3720 <chapt id="relationships">
3721 <heading>Declaring relationships between packages</heading>
3723 <sect id="depsyntax">
3724 <heading>Syntax of relationship fields</heading>
3727 These fields all have a uniform syntax. They are a list of
3728 package names separated by commas.
3732 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3733 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3734 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3735 control file fields of the package, which declare
3736 dependencies on other packages, the package names listed may
3737 also include lists of alternative package names, separated
3738 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3739 if any one of the alternative packages is installed, that
3740 part of the dependency is considered to be satisfied.
3744 All of the fields except for <tt>Provides</tt> may restrict
3745 their applicability to particular versions of each named
3746 package. This is done in parentheses after each individual
3747 package name; the parentheses should contain a relation from
3748 the list below followed by a version number, in the format
3749 described in <ref id="f-Version">.
3753 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3754 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3755 strictly earlier, earlier or equal, exactly equal, later or
3756 equal and strictly later, respectively. The deprecated
3757 forms <tt><</tt> and <tt>></tt> were used to mean
3758 earlier/later or equal, rather than strictly earlier/later,
3759 so they should not appear in new packages (though
3760 <prgn>dpkg</prgn> still supports them).
3764 Whitespace may appear at any point in the version
3765 specification subject to the rules in <ref
3766 id="controlsyntax">, and must appear where it's necessary to
3767 disambiguate; it is not otherwise significant. For
3768 consistency and in case of future changes to
3769 <prgn>dpkg</prgn> it is recommended that a single space be
3770 used after a version relationship and before a version
3771 number; it is also conventional to put a single space after
3772 each comma, on either side of each vertical bar, and before
3773 each open parenthesis.
3777 For example, a list of dependencies might appear as:
3778 <example compact="compact">
3781 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3786 All fields that specify build-time relationships
3787 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3788 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3789 may be restricted to a certain set of architectures. This
3790 is indicated in brackets after each individual package name and
3791 the optional version specification. The brackets enclose a
3792 list of Debian architecture names separated by whitespace.
3793 Exclamation marks may be prepended to each of the names.
3794 (It is not permitted for some names to be prepended with
3795 exclamation marks and others not.) If the current Debian
3796 host architecture is not in this list and there are no
3797 exclamation marks in the list, or it is in the list with a
3798 prepended exclamation mark, the package name and the
3799 associated version specification are ignored completely for
3800 the purposes of defining the relationships.
3805 <example compact="compact">
3807 Build-Depends-Indep: texinfo
3808 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3809 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3814 Note that the binary package relationship fields such as
3815 <tt>Depends</tt> appear in one of the binary package
3816 sections of the control file, whereas the build-time
3817 relationships such as <tt>Build-Depends</tt> appear in the
3818 source package section of the control file (which is the
3823 <sect id="binarydeps">
3824 <heading>Binary Dependencies - <tt>Depends</tt>,
3825 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3826 <tt>Pre-Depends</tt>
3830 Packages can declare in their control file that they have
3831 certain relationships to other packages - for example, that
3832 they may not be installed at the same time as certain other
3833 packages, and/or that they depend on the presence of others.
3837 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3838 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3839 <tt>Conflicts</tt> control file fields.
3843 These six fields are used to declare a dependency
3844 relationship by one package on another. Except for
3845 <tt>Enhances</tt>, they appear in the depending (binary)
3846 package's control file. (<tt>Enhances</tt> appears in the
3847 recommending package's control file.)
3851 A <tt>Depends</tt> field takes effect <em>only</em> when a
3852 package is to be configured. It does not prevent a package
3853 being on the system in an unconfigured state while its
3854 dependencies are unsatisfied, and it is possible to replace
3855 a package whose dependencies are satisfied and which is
3856 properly installed with a different version whose
3857 dependencies are not and cannot be satisfied; when this is
3858 done the depending package will be left unconfigured (since
3859 attempts to configure it will give errors) and will not
3860 function properly. If it is necessary, a
3861 <tt>Pre-Depends</tt> field can be used, which has a partial
3862 effect even when a package is being unpacked, as explained
3863 in detail below. (The other three dependency fields,
3864 <tt>Recommends</tt>, <tt>Suggests</tt> and
3865 <tt>Enhances</tt>, are only used by the various front-ends
3866 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3870 For this reason packages in an installation run are usually
3871 all unpacked first and all configured later; this gives
3872 later versions of packages with dependencies on later
3873 versions of other packages the opportunity to have their
3874 dependencies satisfied.
3878 The <tt>Depends</tt> field thus allows package maintainers
3879 to impose an order in which packages should be configured.
3883 The meaning of the five dependency fields is as follows:
3885 <tag><tt>Depends</tt></tag>
3888 This declares an absolute dependency. A package will
3889 not be configured unless all of the packages listed in
3890 its <tt>Depends</tt> field have been correctly
3895 The <tt>Depends</tt> field should be used if the
3896 depended-on package is required for the depending
3897 package to provide a significant amount of
3902 The <tt>Depends</tt> field should also be used if the
3903 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3904 <prgn>postrm</prgn> scripts require the package to be
3905 present in order to run. Note, however, that the
3906 <prgn>postrm</prgn> cannot rely on any non-essential
3907 packages to be present during the <tt>purge</tt>
3911 <tag><tt>Recommends</tt></tag>
3914 This declares a strong, but not absolute, dependency.
3918 The <tt>Recommends</tt> field should list packages
3919 that would be found together with this one in all but
3920 unusual installations.
3924 <tag><tt>Suggests</tt></tag>
3926 This is used to declare that one package may be more
3927 useful with one or more others. Using this field
3928 tells the packaging system and the user that the
3929 listed packages are related to this one and can
3930 perhaps enhance its usefulness, but that installing
3931 this one without them is perfectly reasonable.
3934 <tag><tt>Enhances</tt></tag>
3936 This field is similar to Suggests but works in the
3937 opposite direction. It is used to declare that a
3938 package can enhance the functionality of another
3942 <tag><tt>Pre-Depends</tt></tag>
3945 This field is like <tt>Depends</tt>, except that it
3946 also forces <prgn>dpkg</prgn> to complete installation
3947 of the packages named before even starting the
3948 installation of the package which declares the
3949 pre-dependency, as follows:
3953 When a package declaring a pre-dependency is about to
3954 be <em>unpacked</em> the pre-dependency can be
3955 satisfied if the depended-on package is either fully
3956 configured, <em>or even if</em> the depended-on
3957 package(s) are only unpacked or half-configured,
3958 provided that they have been configured correctly at
3959 some point in the past (and not removed or partially
3960 removed since). In this case, both the
3961 previously-configured and currently unpacked or
3962 half-configured versions must satisfy any version
3963 clause in the <tt>Pre-Depends</tt> field.
3967 When the package declaring a pre-dependency is about
3968 to be <em>configured</em>, the pre-dependency will be
3969 treated as a normal <tt>Depends</tt>, that is, it will
3970 be considered satisfied only if the depended-on
3971 package has been correctly configured.
3975 <tt>Pre-Depends</tt> should be used sparingly,
3976 preferably only by packages whose premature upgrade or
3977 installation would hamper the ability of the system to
3978 continue with any upgrade that might be in progress.
3982 <tt>Pre-Depends</tt> are also required if the
3983 <prgn>preinst</prgn> script depends on the named
3984 package. It is best to avoid this situation if
3992 When selecting which level of dependency to use you should
3993 consider how important the depended-on package is to the
3994 functionality of the one declaring the dependency. Some
3995 packages are composed of components of varying degrees of
3996 importance. Such a package should list using
3997 <tt>Depends</tt> the package(s) which are required by the
3998 more important components. The other components'
3999 requirements may be mentioned as Suggestions or
4000 Recommendations, as appropriate to the components' relative
4005 <sect id="conflicts">
4006 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4009 When one binary package declares a conflict with another
4010 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4011 refuse to allow them to be installed on the system at the
4016 If one package is to be installed, the other must be removed
4017 first - if the package being installed is marked as
4018 replacing (see <ref id="replaces">) the one on the system,
4019 or the one on the system is marked as deselected, or both
4020 packages are marked <tt>Essential</tt>, then
4021 <prgn>dpkg</prgn> will automatically remove the package
4022 which is causing the conflict, otherwise it will halt the
4023 installation of the new package with an error. This
4024 mechanism is specifically designed to produce an error when
4025 the installed package is <tt>Essential</tt>, but the new
4030 A package will not cause a conflict merely because its
4031 configuration files are still installed; it must be at least
4036 A special exception is made for packages which declare a
4037 conflict with their own package name, or with a virtual
4038 package which they provide (see below): this does not
4039 prevent their installation, and allows a package to conflict
4040 with others providing a replacement for it. You use this
4041 feature when you want the package in question to be the only
4042 package providing some feature.
4046 A <tt>Conflicts</tt> entry should almost never have an
4047 "earlier than" version clause. This would prevent
4048 <prgn>dpkg</prgn> from upgrading or installing the package
4049 which declared such a conflict until the upgrade or removal
4050 of the conflicted-with package had been completed.
4054 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4058 As well as the names of actual ("concrete") packages, the
4059 package relationship fields <tt>Depends</tt>,
4060 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4061 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4062 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4063 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4064 may mention "virtual packages".
4068 A <em>virtual package</em> is one which appears in the
4069 <tt>Provides</tt> control file field of another package.
4070 The effect is as if the package(s) which provide a
4071 particular virtual package name had been listed by name
4072 everywhere the virtual package name appears. (See also <ref
4077 If there are both concrete and virtual packages of the same
4078 name, then the dependency may be satisfied (or the conflict
4079 caused) by either the concrete package with the name in
4080 question or any other concrete package which provides the
4081 virtual package with the name in question. This is so that,
4082 for example, supposing we have
4083 <example compact="compact">
4087 and someone else releases an enhanced version of the
4088 <tt>bar</tt> package (for example, a non-US variant), they
4090 <example compact="compact">
4094 and the <tt>bar-plus</tt> package will now also satisfy the
4095 dependency for the <tt>foo</tt> package.
4099 If a dependency or a conflict has a version number attached
4100 then only real packages will be considered to see whether
4101 the relationship is satisfied (or the prohibition violated,
4102 for a conflict) - it is assumed that a real package which
4103 provides the virtual package is not of the "right" version.
4104 So, a <tt>Provides</tt> field may not contain version
4105 numbers, and the version number of the concrete package
4106 which provides a particular virtual package will not be
4107 looked at when considering a dependency on or conflict with
4108 the virtual package name.
4112 It is likely that the ability will be added in a future
4113 release of <prgn>dpkg</prgn> to specify a version number for
4114 each virtual package it provides. This feature is not yet
4115 present, however, and is expected to be used only
4120 If you want to specify which of a set of real packages
4121 should be the default to satisfy a particular dependency on
4122 a virtual package, you should list the real package as an
4123 alternative before the virtual one.
4128 <sect id="replaces"><heading>Overwriting files and replacing
4129 packages - <tt>Replaces</tt></heading>
4132 Packages can declare in their control file that they should
4133 overwrite files in certain other packages, or completely
4134 replace other packages. The <tt>Replaces</tt> control file
4135 field has these two distinct purposes.
4138 <sect1><heading>Overwriting files in other packages</heading>
4141 Firstly, as mentioned before, it is usually an error for a
4142 package to contain files which are on the system in
4147 However, if the overwriting package declares that it
4148 <tt>Replaces</tt> the one containing the file being
4149 overwritten, then <prgn>dpkg</prgn> will replace the file
4150 from the old package with that from the new. The file
4151 will no longer be listed as "owned" by the old package.
4155 If a package is completely replaced in this way, so that
4156 <prgn>dpkg</prgn> does not know of any files it still
4157 contains, it is considered to have "disappeared". It will
4158 be marked as not wanted on the system (selected for
4159 removal) and not installed. Any <tt>conffile</tt>s
4160 details noted for the package will be ignored, as they
4161 will have been taken over by the overwriting package. The
4162 package's <prgn>postrm</prgn> script will be run with a
4163 special argument to allow the package to do any final
4164 cleanup required. See <ref id="mscriptsinstact">.
4167 Replaces is a one way relationship -- you have to
4168 install the replacing package after the replaced
4175 For this usage of <tt>Replaces</tt>, virtual packages (see
4176 <ref id="virtual">) are not considered when looking at a
4177 <tt>Replaces</tt> field - the packages declared as being
4178 replaced must be mentioned by their real names.
4182 Furthermore, this usage of <tt>Replaces</tt> only takes
4183 effect when both packages are at least partially on the
4184 system at once, so that it can only happen if they do not
4185 conflict or if the conflict has been overridden.
4190 <sect1><heading>Replacing whole packages, forcing their
4194 Secondly, <tt>Replaces</tt> allows the packaging system to
4195 resolve which package should be removed when there is a
4196 conflict - see <ref id="conflicts">. This usage only
4197 takes effect when the two packages <em>do</em> conflict,
4198 so that the two usages of this field do not interfere with
4203 In this situation, the package declared as being replaced
4204 can be a virtual package, so for example, all mail
4205 transport agents (MTAs) would have the following fields in
4206 their control files:
4207 <example compact="compact">
4208 Provides: mail-transport-agent
4209 Conflicts: mail-transport-agent
4210 Replaces: mail-transport-agent
4212 ensuring that only one MTA can be installed at any one
4217 <sect id="sourcebinarydeps">
4218 <heading>Relationships between source and binary packages -
4219 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4220 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4224 Source packages that require certain binary packages to be
4225 installed or absent at the time of building the package
4226 can declare relationships to those binary packages.
4230 This is done using the <tt>Build-Depends</tt>,
4231 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4232 <tt>Build-Conflicts-Indep</tt> control file fields.
4236 Build-dependencies on "build-essential" binary packages can be
4237 omitted. Please see <ref id="pkg-relations"> for more information.
4241 The dependencies and conflicts they define must be satisfied
4242 (as defined earlier for binary packages) in order to invoke
4243 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4245 If you make "build-arch" or "binary-arch", you need
4246 Build-Depends. If you make "build-indep" or
4247 "binary-indep", you need Build-Depends and
4248 Build-Depends-Indep. If you make "build" or "binary",
4252 There is no Build-Depends-Arch; the autobuilders will
4253 only need the Build-Depends if they know how to build
4254 only build-arch and binary-arch. Anyone building the
4255 build-indep/binary-indep targets is basically assumed to
4256 be building the whole package and so installs all build
4260 The purpose of the original split, I recall, was so that
4261 the autobuilders wouldn't need to install extra packages
4262 needed only for the binary-indep targets. But without a
4263 build-arch/build-indep split, this didn't work, since
4264 most of the work is done in the build target, not in the
4270 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4272 The <tt>Build-Depends</tt> and
4273 <tt>Build-Conflicts</tt> fields must be satisfied when
4274 any of the following targets is invoked:
4275 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4276 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4277 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4279 <tag><tt>Build-Depends-Indep</tt>,
4280 <tt>Build-Conflicts-Indep</tt></tag>
4282 The <tt>Build-Depends-Indep</tt> and
4283 <tt>Build-Conflicts-Indep</tt> fields must be
4284 satisfied when any of the following targets is
4285 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4286 <tt>binary</tt> and <tt>binary-indep</tt>.
4296 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4299 Packages containing shared libraries must be constructed with
4300 a little care to make sure that the shared library is always
4301 available. This is especially important for packages whose
4302 shared libraries are vitally important, such as the C library
4303 (currently <tt>libc6</tt>).
4307 Packages involving shared libraries should be split up into
4308 several binary packages. This section mostly deals with how
4309 this separation is to be accomplished; rules for files within
4310 the shared library packages are in <ref id="libraries"> instead.
4313 <sect id="sharedlibs-runtime">
4314 <heading>Run-time shared libraries</heading>
4317 The run-time shared library needs to be placed in a package called
4318 <package><var>libraryname</var><var>soversion</var></package>, where
4319 <file><var>soversion</var></file> is the version number in the
4320 soname of the shared library<footnote>
4321 The soname is the shared object name: it's the thing
4322 that has to match exactly between building an executable
4323 and running it for the dynamic linker to be able run the
4324 program. For example, if the soname of the library is
4325 <file>libfoo.so.6</file>, the library package would be
4326 called <file>libfoo6</file>.
4328 Alternatively, if it would be confusing to directly append
4329 <var>soversion</var> to <var>libraryname</var> (e.g. because
4330 <var>libraryname</var> itself ends in a number), you may use
4331 <package><var>libraryname</var>-<var>soversion</var></package> and
4332 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4337 If you have several shared libraries built from the same
4338 source tree you may lump them all together into a single
4339 shared library package, provided that you change all of
4340 their sonames at once (so that you don't get filename
4341 clashes if you try to install different versions of the
4342 combined shared libraries package).
4346 The package should install the shared libraries under
4347 their normal names. For example, the <package>libgdbm3</package>
4348 package should install <file>libgdbm.so.3.0.0</file> as
4349 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4350 renamed or re-linked by any <prgn>prerm</prgn> or
4351 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4352 of renaming things safely without affecting running programs,
4353 and attempts to interfere with this are likely to lead to
4358 Shared libraries should not be installed executable, since
4359 the dynamic linker does not require this and trying to
4360 execute a shared library usually results in a core dump.
4364 The run-time library package should include the symbolic link that
4365 <prgn>ldconfig</prgn> would create for the shared libraries.
4366 For example, the <package>libgdbm3</package> package should include
4367 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4368 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4369 linker (for example <prgn>ld.so</prgn> or
4370 <prgn>ld-linux.so.*</prgn>) can find the library between the
4371 time that <prgn>dpkg</prgn> installs it and the time that
4372 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4374 The package management system requires the library to be
4375 placed before the symbolic link pointing to it in the
4376 <file>.deb</file> file. This is so that when
4377 <prgn>dpkg</prgn> comes to install the symlink
4378 (overwriting the previous symlink pointing at an older
4379 version of the library), the new shared library is already
4380 in place. In the past, this was achieved by creating the
4381 library in the temporary packaging directory before
4382 creating the symlink. Unfortunately, this was not always
4383 effective, since the building of the tar file in the
4384 <file>.deb</file> depended on the behavior of the underlying
4385 file system. Some file systems (such as reiserfs) reorder
4386 the files so that the order of creation is forgotten.
4387 Since version 1.7.0, <prgn>dpkg</prgn>
4388 reorders the files itself as necessary when building a
4389 package. Thus it is no longer important to concern
4390 oneself with the order of file creation.
4394 <sect1 id="ldconfig">
4395 <heading><tt>ldconfig</tt></heading>
4398 Any package installing shared libraries in one of the default
4399 library directories of the dynamic linker (which are currently
4400 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4401 listed in <file>/etc/ld.so.conf</file><footnote>
4403 <list compact="compact">
4404 <item>/usr/X11R6/lib/Xaw3d</item>
4405 <item>/usr/local/lib</item>
4406 <item>/usr/lib/libc5-compat</item>
4407 <item>/lib/libc5-compat</item>
4408 <item>/usr/X11R6/lib</item>
4411 must use <prgn>ldconfig</prgn> to update the shared library
4416 The package must call <prgn>ldconfig</prgn> in the
4417 <prgn>postinst</prgn> script if the first argument is
4418 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4419 optionally invoke <prgn>ldconfig</prgn> at other times. The
4420 package should call <prgn>ldconfig</prgn> in the
4421 <prgn>postrm</prgn> script if the first argument is
4422 <tt>remove</tt>. The maintainer scripts must not invoke
4423 <prgn>ldconfig</prgn> under any circumstances other than those
4424 described in this paragraph.<footnote>
4426 During install or upgrade, the preinst is called before
4427 the new files are installed, so calling "ldconfig" is
4428 pointless. The preinst of an existing package can also be
4429 called if an upgrade fails. However, this happens during
4430 the critical time when a shared libs may exist on-disk
4431 under a temporary name. Thus, it is dangerous and
4432 forbidden by current policy to call "ldconfig" at this
4437 When a package is installed or upgraded, "postinst
4438 configure" runs after the new files are safely on-disk.
4439 Since it is perfectly safe to invoke ldconfig
4440 unconditionally in a postinst, it is OK for a package to
4441 simply put ldconfig in its postinst without checking the
4442 argument. The postinst can also be called to recover from
4443 a failed upgrade. This happens before any new files are
4444 unpacked, so there is no reason to call "ldconfig" at this
4449 For a package that is being removed, prerm is
4450 called with all the files intact, so calling ldconfig is
4451 useless. The other calls to "prerm" happen in the case of
4452 upgrade at a time when all the files of the old package
4453 are on-disk, so again calling "ldconfig" is pointless.
4457 postrm, on the other hand, is called with the "remove"
4458 argument just after the files are removed, so this is the
4459 proper time to call "ldconfig" to notify the system of the
4460 fact shared libraries from the package are removed.
4461 The postrm can be called at several other times. At the
4462 time of "postrm purge", "postrm abort-install", or "postrm
4463 abort-upgrade", calling "ldconfig" is useless because the
4464 shared lib files are not on-disk. However, when "postrm"
4465 is invoked with arguments "upgrade", "failed-upgrade", or
4466 "disappear", a shared lib may exist on-disk under a
4475 <sect id="sharedlibs-runtime-progs">
4476 <heading>Run-time support programs</heading>
4479 If your package has some run-time support programs which use
4480 the shared library you must not put them in the shared
4481 library package. If you do that then you won't be able to
4482 install several versions of the shared library without
4483 getting filename clashes.
4487 Instead, either create another package for the runtime binaries
4488 (this package might typically be named
4489 <package><var>libraryname</var>-runtime</package>; note the absence
4490 of the <var>soversion</var> in the package name), or if the
4491 development package is small, include them in there.
4495 <sect id="sharedlibs-static">
4496 <heading>Static libraries</heading>
4499 The static library (<file><var>libraryname.a</var></file>)
4500 is usually provided in addition to the shared version.
4501 It is placed into the development package (see below).
4505 In some cases, it is acceptable for a library to be
4506 available in static form only; these cases include:
4508 <item>libraries for languages whose shared library support
4509 is immature or unstable</item>
4510 <item>libraries whose interfaces are in flux or under
4511 development (commonly the case when the library's
4512 major version number is zero, or where the ABI breaks
4513 across patchlevels)</item>
4514 <item>libraries which are explicitly intended to be
4515 available only in static form by their upstream
4520 <sect id="sharedlibs-dev">
4521 <heading>Development files</heading>
4524 The development files associated to a shared library need to be
4525 placed in a package called
4526 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4527 or if you prefer only to support one development version at a
4528 time, <package><var>libraryname</var>-dev</package>.
4532 In case several development versions of a library exist, you may
4533 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4534 <ref id="conflicts">) to ensure that the user only installs one
4535 development version at a time (as different development versions are
4536 likely to have the same header files in them, which would cause a
4537 filename clash if both were installed).
4541 The development package should contain a symlink for the associated
4542 shared library without a version number. For example, the
4543 <package>libgdbm-dev</package> package should include a symlink
4544 from <file>/usr/lib/libgdbm.so</file> to
4545 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4546 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4547 <file>libgdbm.so</file> when compiling dynamically.
4551 <sect id="sharedlibs-intradeps">
4552 <heading>Dependencies between the packages of the same library</heading>
4555 Typically the development version should have an exact
4556 version dependency on the runtime library, to make sure that
4557 compilation and linking happens correctly. The
4558 <tt>${Source-Version}</tt> substitution variable can be
4559 useful for this purpose.
4563 <sect id="sharedlibs-shlibdeps">
4564 <heading>Dependencies between the library and other packages -
4565 the <tt>shlibs</tt> system</heading>
4568 If a package contains a binary or library which links to a
4569 shared library, we must ensure that when the package is
4570 installed on the system, all of the libraries needed are
4571 also installed. This requirement led to the creation of the
4572 <tt>shlibs</tt> system, which is very simple in its design:
4573 any package which <em>provides</em> a shared library also
4574 provides information on the package dependencies required to
4575 ensure the presence of this library, and any package which
4576 <em>uses</em> a shared library uses this information to
4577 determine the dependencies it requires. The files which
4578 contain the mapping from shared libraries to the necessary
4579 dependency information are called <file>shlibs</file> files.
4583 Thus, when a package is built which contains any shared
4584 libraries, it must provide a <file>shlibs</file> file for other
4585 packages to use, and when a package is built which contains
4586 any shared libraries or compiled binaries, it must run
4587 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4588 on these to determine the libraries used and hence the
4589 dependencies needed by this package.<footnote>
4591 In the past, the shared libraries linked to were
4592 determined by calling <prgn>ldd</prgn>, but now
4593 <prgn>objdump</prgn> is used to do this. The only
4594 change this makes to package building is that
4595 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4596 libraries, whereas in the past this was unnecessary.
4597 The rest of this footnote explains the advantage that
4602 We say that a binary <tt>foo</tt> <em>directly</em> uses
4603 a library <tt>libbar</tt> if it is explicitly linked
4604 with that library (that is, it uses the flag
4605 <tt>-lbar</tt> during the linking stage). Other
4606 libraries that are needed by <tt>libbar</tt> are linked
4607 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4608 linker will load them automatically when it loads
4609 <tt>libbar</tt>. A package should depend on
4610 the libraries it directly uses, and the dependencies for
4611 those libraries should automatically pull in the other
4616 Unfortunately, the <prgn>ldd</prgn> program shows both
4617 the directly and indirectly used libraries, meaning that
4618 the dependencies determined included both direct and
4619 indirect dependencies. The use of <prgn>objdump</prgn>
4620 avoids this problem by determining only the directly
4625 A good example of where this helps is the following. We
4626 could update <tt>libimlib</tt> with a new version that
4627 supports a new graphics format called dgf (but retaining
4628 the same major version number). If we used the old
4629 <prgn>ldd</prgn> method, every package that uses
4630 <tt>libimlib</tt> would need to be recompiled so it
4631 would also depend on <tt>libdgf</tt> or it wouldn't run
4632 due to missing symbols. However with the new system,
4633 packages using <tt>libimlib</tt> can rely on
4634 <tt>libimlib</tt> itself having the dependency on
4635 <tt>libdgf</tt> and so they would not need rebuilding.
4641 In the following sections, we will first describe where the
4642 various <tt>shlibs</tt> files are to be found, then how to
4643 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4644 file format and how to create them if your package contains a
4649 <heading>The <tt>shlibs</tt> files present on the system</heading>
4652 There are several places where <tt>shlibs</tt> files are
4653 found. The following list gives them in the order in which
4655 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4656 (The first one which gives the required information is used.)
4662 <p><file>debian/shlibs.local</file></p>
4665 This lists overrides for this package. Its use is
4666 described below (see <ref id="shlibslocal">).
4671 <p><file>/etc/dpkg/shlibs.override</file></p>
4674 This lists global overrides. This list is normally
4675 empty. It is maintained by the local system
4681 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4684 When packages are being built, any
4685 <file>debian/shlibs</file> files are copied into the
4686 control file area of the temporary build directory and
4687 given the name <file>shlibs</file>. These files give
4688 details of any shared libraries included in the
4690 An example may help here. Let us say that the
4691 source package <tt>foo</tt> generates two binary
4692 packages, <tt>libfoo2</tt> and
4693 <tt>foo-runtime</tt>. When building the binary
4694 packages, the two packages are created in the
4695 directories <file>debian/libfoo2</file> and
4696 <file>debian/foo-runtime</file> respectively.
4697 (<file>debian/tmp</file> could be used instead of one
4698 of these.) Since <tt>libfoo2</tt> provides the
4699 <tt>libfoo</tt> shared library, it will require a
4700 <tt>shlibs</tt> file, which will be installed in
4701 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4703 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4704 when <prgn>dpkg-shlibdeps</prgn> is run on the
4706 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4708 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4709 determine whether <tt>foo-prog</tt>'s library
4710 dependencies are satisfied by any of the libraries
4711 provided by <tt>libfoo2</tt>. For this reason,
4712 <prgn>dpkg-shlibdeps</prgn> must only be run once
4713 all of the individual binary packages'
4714 <tt>shlibs</tt> files have been installed into the
4721 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4724 These are the <file>shlibs</file> files corresponding to
4725 all of the packages installed on the system, and are
4726 maintained by the relevant package maintainers.
4731 <p><file>/etc/dpkg/shlibs.default</file></p>
4734 This file lists any shared libraries whose packages
4735 have failed to provide correct <file>shlibs</file> files.
4736 It was used when the <file>shlibs</file> setup was first
4737 introduced, but it is now normally empty. It is
4738 maintained by the <tt>dpkg</tt> maintainer.
4746 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4747 <file>shlibs</file> files</heading>
4751 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4752 into your <file>debian/rules</file> file. If your package
4753 contains only compiled binaries and libraries (but no scripts),
4754 you can use a command such as:
4755 <example compact="compact">
4756 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4757 debian/tmp/usr/lib/*
4759 Otherwise, you will need to explicitly list the compiled
4760 binaries and libraries.<footnote>
4761 If you are using <tt>debhelper</tt>, the
4762 <prgn>dh_shlibdeps</prgn> program will do this work for
4763 you. It will also correctly handle multi-binary
4769 This command puts the dependency information into the
4770 <file>debian/substvars</file> file, which is then used by
4771 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4772 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4773 field in the control file for this to work.
4777 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4778 done. If it does complain you might need to create your own
4779 <file>debian/shlibs.local</file> file, as explained below (see
4780 <ref id="shlibslocal">).
4784 If you have multiple binary packages, you will need to call
4785 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4786 compiled libraries or binaries. In such a case, you will
4787 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4788 utilities to specify a different <file>substvars</file> file.
4792 For more details on dpkg-shlibdeps, please see
4793 <ref id="pkg-dpkg-shlibdeps"> and
4794 <manref name="dpkg-shlibdeps" section="1">.
4799 <heading>The <file>shlibs</file> File Format</heading>
4802 Each <file>shlibs</file> file has the same format. Lines
4803 beginning with <tt>#</tt> are considered to be comments and
4804 are ignored. Each line is of the form:
4805 <example compact="compact">
4806 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4811 We will explain this by reference to the example of the
4812 <tt>zlib1g</tt> package, which (at the time of writing)
4813 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4817 <var>library-name</var> is the name of the shared library,
4818 in this case <tt>libz</tt>. (This must match the name part
4819 of the soname, see below.)
4823 <var>soname-version-number</var> is the version part of the
4824 soname of the library. The soname is the thing that must
4825 exactly match for the library to be recognized by the
4826 dynamic linker, and is usually of the form
4827 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4828 example, <tt>libz.so.1</tt>.<footnote>
4829 This can be determined using the command
4830 <example compact="compact">
4831 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4834 The version part is the part which comes after
4835 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4839 <var>dependencies</var> has the same syntax as a dependency
4840 field in a binary package control file. It should give
4841 details of which packages are required to satisfy a binary
4842 built against the version of the library contained in the
4843 package. See <ref id="depsyntax"> for details.
4847 In our example, if the first version of the <tt>zlib1g</tt>
4848 package which contained a minor number of at least
4849 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4850 <tt>shlibs</tt> entry for this library could say:
4851 <example compact="compact">
4852 libz 1 zlib1g (>= 1:1.1.3)
4854 The version-specific dependency is to avoid warnings from
4855 the dynamic linker about using older shared libraries with
4861 <heading>Providing a <file>shlibs</file> file</heading>
4864 If your package provides a shared library, you should create
4865 a <file>shlibs</file> file following the format described above.
4866 It is usual to call this file <file>debian/shlibs</file> (but if
4867 you have multiple binary packages, you might want to call it
4868 <file>debian/shlibs.<var>package</var></file> instead). Then
4869 let <file>debian/rules</file> install it in the control area:
4870 <example compact="compact">
4871 install -m644 debian/shlibs debian/tmp/DEBIAN
4873 or, in the case of a multi-binary package:
4874 <example compact="compact">
4875 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4877 An alternative way of doing this is to create the
4878 <file>shlibs</file> file in the control area directly from
4879 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4880 file at all,<footnote>
4881 This is what <prgn>dh_makeshlibs</prgn> in the
4882 <tt>debhelper</tt> suite does.
4884 since the <file>debian/shlibs</file> file itself is ignored by
4885 <prgn>dpkg-shlibdeps</prgn>.
4889 As <prgn>dpkg-shlibdeps</prgn> reads the
4890 <file>DEBIAN/shlibs</file> files in all of the binary packages
4891 being built from this source package, all of the
4892 <file>DEBIAN/shlibs</file> files should be installed before
4893 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4898 <sect1 id="shlibslocal">
4899 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4902 This file is intended only as a <em>temporary</em> fix if
4903 your binaries or libraries depend on a library whose package
4904 does not yet provide a correct <file>shlibs</file> file.
4908 We will assume that you are trying to package a binary
4909 <tt>foo</tt>. When you try running
4910 <prgn>dpkg-shlibdeps</prgn> you get the following error
4911 message (<tt>-O</tt> displays the dependency information on
4912 <tt>stdout</tt> instead of writing it to
4913 <tt>debian/substvars</tt>, and the lines have been wrapped
4914 for ease of reading):
4915 <example compact="compact">
4916 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4917 dpkg-shlibdeps: warning: unable to find dependency
4918 information for shared library libbar (soname 1,
4919 path /usr/lib/libbar.so.1, dependency field Depends)
4920 shlibs:Depends=libc6 (>= 2.2.2-2)
4922 You can then run <prgn>ldd</prgn> on the binary to find the
4923 full location of the library concerned:
4924 <example compact="compact">
4926 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4927 libc.so.6 => /lib/libc.so.6 (0x40032000)
4928 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4930 So the <prgn>foo</prgn> binary depends on the
4931 <prgn>libbar</prgn> shared library, but no package seems to
4932 provide a <file>*.shlibs</file> file handling
4933 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4934 determine the package responsible:
4935 <example compact="compact">
4936 $ dpkg -S /usr/lib/libbar.so.1
4937 bar1: /usr/lib/libbar.so.1
4938 $ dpkg -s bar1 | grep Version
4941 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4942 is the one we are using. Now we can file a bug against the
4943 <tt>bar1</tt> package and create our own
4944 <file>debian/shlibs.local</file> to locally fix the problem.
4945 Including the following line into your
4946 <file>debian/shlibs.local</file> file:
4947 <example compact="compact">
4948 libbar 1 bar1 (>= 1.0-1)
4950 should allow the package build to work.
4954 As soon as the maintainer of <tt>bar1</tt> provides a
4955 correct <file>shlibs</file> file, you should remove this line
4956 from your <file>debian/shlibs.local</file> file. (You should
4957 probably also then have a versioned <tt>Build-Depends</tt>
4958 on <tt>bar1</tt> to help ensure that others do not have the
4959 same problem building your package.)
4968 <chapt id="opersys"><heading>The Operating System</heading>
4971 <heading>Filesystem hierarchy</heading>
4975 <heading>Filesystem Structure</heading>
4978 The location of all installed files and directories must
4979 comply with the Filesystem Hierarchy Standard (FHS),
4980 version 2.1, except where doing so would violate other
4981 terms of Debian Policy. The version of this document
4982 referred here can be found in the <tt>debian-policy</tt>
4984 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4985 name="FHS (Debian copy)"> alongside this manual (or, if
4986 you have the <package>debian-policy</package> installed,
4988 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4989 (local copy)">). The
4990 latest version, which may be a more recent version, may
4992 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4993 Specific questions about following the standard may be
4994 asked on the <tt>debian-devel</tt> mailing list, or
4995 referred to the FHS mailing list (see the
4996 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5002 <heading>Site-specific programs</heading>
5005 As mandated by the FHS, packages must not place any
5006 files in <file>/usr/local</file>, either by putting them in
5007 the file system archive to be unpacked by <prgn>dpkg</prgn>
5008 or by manipulating them in their maintainer scripts.
5012 However, the package may create empty directories below
5013 <file>/usr/local</file> so that the system administrator knows
5014 where to place site-specific files. These directories
5015 should be removed on package removal if they are
5020 Note, that this applies only to directories <em>below</em>
5021 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5022 Packages must not create sub-directories in the directory
5023 <file>/usr/local</file> itself, except those listed in FHS,
5024 section 4.5. However, you may create directories below
5025 them as you wish. You must not remove any of the
5026 directories listed in 4.5, even if you created them.
5030 Since <file>/usr/local</file> can be mounted read-only from a
5031 remote server, these directories must be created and
5032 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5033 maintainer scripts and not be included in the
5034 <file>.deb</file> archive. These scripts must not fail if
5035 either of these operations fail.
5039 For example, the <tt>emacsen-common</tt> package could
5040 contain something like
5041 <example compact="compact">
5042 if [ ! -e /usr/local/share/emacs ]
5044 if mkdir /usr/local/share/emacs 2>/dev/null
5046 chown root:staff /usr/local/share/emacs
5047 chmod 2775 /usr/local/share/emacs
5051 in its <prgn>postinst</prgn> script, and
5052 <example compact="compact">
5053 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5054 rmdir /usr/local/share/emacs 2>/dev/null || true
5056 in the <prgn>prerm</prgn> script. (Note that this form is
5057 used to ensure that if the script is interrupted, the
5058 directory <file>/usr/local/share/emacs</file> will still be
5063 If you do create a directory in <file>/usr/local</file> for
5064 local additions to a package, you should ensure that
5065 settings in <file>/usr/local</file> take precedence over the
5066 equivalents in <file>/usr</file>.
5070 However, because <file>/usr/local</file> and its contents are
5071 for exclusive use of the local administrator, a package
5072 must not rely on the presence or absence of files or
5073 directories in <file>/usr/local</file> for normal operation.
5077 The <file>/usr/local</file> directory itself and all the
5078 subdirectories created by the package should (by default) have
5079 permissions 2775 (group-writable and set-group-id) and be
5080 owned by <tt>root.staff</tt>.
5085 <heading>The system-wide mail directory</heading>
5087 The system-wide mail directory is <file>/var/mail</file>. This
5088 directory is part of the base system and should not owned
5089 by any particular mail agents. The use of the old
5090 location <file>/var/spool/mail</file> is deprecated, even
5091 though the spool may still be physically located there.
5092 To maintain partial upgrade compatibility for systems
5093 which have <file>/var/spool/mail</file> as their physical mail
5094 spool, packages using <file>/var/mail</file> must depend on
5095 either <package>libc6</package> (>= 2.1.3-13), or on
5096 <package>base-files</package> (>= 2.2.0), or on later
5097 versions of either one of these packages.
5103 <heading>Users and groups</heading>
5106 <heading>Introduction</heading>
5108 The Debian system can be configured to use either plain or
5113 Some user ids (UIDs) and group ids (GIDs) are reserved
5114 globally for use by certain packages. Because some
5115 packages need to include files which are owned by these
5116 users or groups, or need the ids compiled into binaries,
5117 these ids must be used on any Debian system only for the
5118 purpose for which they are allocated. This is a serious
5119 restriction, and we should avoid getting in the way of
5120 local administration policies. In particular, many sites
5121 allocate users and/or local system groups starting at 100.
5125 Apart from this we should have dynamically allocated ids,
5126 which should by default be arranged in some sensible
5127 order, but the behavior should be configurable.
5131 Packages other than <tt>base-passwd</tt> must not modify
5132 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5133 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5138 <heading>UID and GID classes</heading>
5140 The UID and GID numbers are divided into classes as
5146 Globally allocated by the Debian project, the same
5147 on every Debian system. These ids will appear in
5148 the <file>passwd</file> and <file>group</file> files of all
5149 Debian systems, new ids in this range being added
5150 automatically as the <tt>base-passwd</tt> package is
5155 Packages which need a single statically allocated
5156 uid or gid should use one of these; their
5157 maintainers should ask the <tt>base-passwd</tt>
5165 Dynamically allocated system users and groups.
5166 Packages which need a user or group, but can have
5167 this user or group allocated dynamically and
5168 differently on each system, should use <tt>adduser
5169 --system</tt> to create the group and/or user.
5170 <prgn>adduser</prgn> will check for the existence of
5171 the user or group, and if necessary choose an unused
5172 id based on the ranges specified in
5173 <file>adduser.conf</file>.
5177 <tag>1000-29999:</tag>
5180 Dynamically allocated user accounts. By default
5181 <prgn>adduser</prgn> will choose UIDs and GIDs for
5182 user accounts in this range, though
5183 <file>adduser.conf</file> may be used to modify this
5188 <tag>30000-59999:</tag>
5193 <tag>60000-64999:</tag>
5196 Globally allocated by the Debian project, but only
5197 created on demand. The ids are allocated centrally
5198 and statically, but the actual accounts are only
5199 created on users' systems on demand.
5203 These ids are for packages which are obscure or
5204 which require many statically-allocated ids. These
5205 packages should check for and create the accounts in
5206 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5207 <prgn>adduser</prgn> if it has this facility) if
5208 necessary. Packages which are likely to require
5209 further allocations should have a "hole" left after
5210 them in the allocation, to give them room to
5215 <tag>65000-65533:</tag>
5223 User <tt>nobody</tt>. The corresponding gid refers
5224 to the group <tt>nogroup</tt>.
5231 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5232 not</em> be used, because it is the error return
5241 <sect id="sysvinit">
5242 <heading>System run levels and <file>init.d</file> scripts</heading>
5244 <sect1 id="/etc/init.d">
5245 <heading>Introduction</heading>
5248 The <file>/etc/init.d</file> directory contains the scripts
5249 executed by <prgn>init</prgn> at boot time and when the
5250 init state (or "runlevel") is changed (see <manref
5251 name="init" section="8">).
5255 There are at least two different, yet functionally
5256 equivalent, ways of handling these scripts. For the sake
5257 of simplicity, this document describes only the symbolic
5258 link method. However, it must not be assumed by maintainer
5259 scripts that this method is being used, and any automated
5260 manipulation of the various runlevel behaviours by
5261 maintainer scripts must be performed using
5262 <prgn>update-rc.d</prgn> as described below and not by
5263 manually installing or removing symlinks. For information
5264 on the implementation details of the other method,
5265 implemented in the <tt>file-rc</tt> package, please refer
5266 to the documentation of that package.
5270 These scripts are referenced by symbolic links in the
5271 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5272 runlevels, <prgn>init</prgn> looks in the directory
5273 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5274 execute, where <tt><var>n</var></tt> is the runlevel that
5275 is being changed to, or <tt>S</tt> for the boot-up
5280 The names of the links all have the form
5281 <file>S<var>mm</var><var>script</var></file> or
5282 <file>K<var>mm</var><var>script</var></file> where
5283 <var>mm</var> is a two-digit number and <var>script</var>
5284 is the name of the script (this should be the same as the
5285 name of the actual script in <file>/etc/init.d</file>).
5289 When <prgn>init</prgn> changes runlevel first the targets
5290 of the links whose names start with a <tt>K</tt> are
5291 executed, each with the single argument <tt>stop</tt>,
5292 followed by the scripts prefixed with an <tt>S</tt>, each
5293 with the single argument <tt>start</tt>. (The links are
5294 those in the <file>/etc/rc<var>n</var>.d</file> directory
5295 corresponding to the new runlevel.) The <tt>K</tt> links
5296 are responsible for killing services and the <tt>S</tt>
5297 link for starting services upon entering the runlevel.
5301 For example, if we are changing from runlevel 2 to
5302 runlevel 3, init will first execute all of the <tt>K</tt>
5303 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5304 all of the <tt>S</tt> prefixed scripts in that directory.
5305 The links starting with <tt>K</tt> will cause the
5306 referred-to file to be executed with an argument of
5307 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5312 The two-digit number <var>mm</var> is used to determine
5313 the order in which to run the scripts: low-numbered links
5314 have their scripts run first. For example, the
5315 <tt>K20</tt> scripts will be executed before the
5316 <tt>K30</tt> scripts. This is used when a certain service
5317 must be started before another. For example, the name
5318 server <prgn>bind</prgn> might need to be started before
5319 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5320 can set up its access lists. In this case, the script
5321 that starts <prgn>bind</prgn> would have a lower number
5322 than the script that starts <prgn>inn</prgn> so that it
5324 <example compact="compact">
5331 The two runlevels 0 (halt) and 6 (reboot) are slightly
5332 different. In these runlevels, the links with an
5333 <tt>S</tt> prefix are still called after those with a
5334 <tt>K</tt> prefix, but they too are called with the single
5335 argument <tt>stop</tt>.
5339 Also, if the script name ends <tt>.sh</tt>, the script
5340 will be sourced in runlevel <tt>S</tt> rather that being
5341 run in a forked subprocess, but will be explicitly run by
5342 <prgn>sh</prgn> in all other runlevels.
5347 <heading>Writing the scripts</heading>
5350 Packages that include daemons for system services should
5351 place scripts in <file>/etc/init.d</file> to start or stop
5352 services at boot time or during a change of runlevel.
5353 These scripts should be named
5354 <file>/etc/init.d/<var>package</var></file>, and they should
5355 accept one argument, saying what to do:
5358 <tag><tt>start</tt></tag>
5359 <item>start the service,</item>
5361 <tag><tt>stop</tt></tag>
5362 <item>stop the service,</item>
5364 <tag><tt>restart</tt></tag>
5365 <item>stop and restart the service if it's already running,
5366 otherwise start the service</item>
5368 <tag><tt>reload</tt></tag>
5369 <item><p>cause the configuration of the service to be
5370 reloaded without actually stopping and restarting
5373 <tag><tt>force-reload</tt></tag>
5374 <item>cause the configuration to be reloaded if the
5375 service supports this, otherwise restart the
5379 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5380 <tt>force-reload</tt> options should be supported by all
5381 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5386 The <file>init.d</file> scripts should ensure that they will
5387 behave sensibly if invoked with <tt>start</tt> when the
5388 service is already running, or with <tt>stop</tt> when it
5389 isn't, and that they don't kill unfortunately-named user
5390 processes. The best way to achieve this is usually to use
5391 <prgn>start-stop-daemon</prgn>.
5395 If a service reloads its configuration automatically (as
5396 in the case of <prgn>cron</prgn>, for example), the
5397 <tt>reload</tt> option of the <file>init.d</file> script
5398 should behave as if the configuration has been reloaded
5403 The <file>/etc/init.d</file> scripts must be treated as
5404 configuration files, either (if they are present in the
5405 package, that is, in the .deb file) by marking them as
5406 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5407 by managing them correctly in the maintainer scripts (see
5408 <ref id="config-files">). This is important since we want
5409 to give the local system administrator the chance to adapt
5410 the scripts to the local system, e.g., to disable a
5411 service without de-installing the package, or to specify
5412 some special command line options when starting a service,
5413 while making sure her changes aren't lost during the next
5418 These scripts should not fail obscurely when the
5419 configuration files remain but the package has been
5420 removed, as configuration files remain on the system after
5421 the package has been removed. Only when <prgn>dpkg</prgn>
5422 is executed with the <tt>--purge</tt> option will
5423 configuration files be removed. In particular, as the
5424 <file>/etc/init.d/<var>package</var></file> script itself is
5425 usually a <tt>conffile</tt>, it will remain on the system
5426 if the package is removed but not purged. Therefore, you
5427 should include a <tt>test</tt> statement at the top of the
5429 <example compact="compact">
5430 test -f <var>program-executed-later-in-script</var> || exit 0
5435 Often there are some variables in the <file>init.d</file>
5436 scripts whose values control the behaviour of the scripts,
5437 and which a system administrator is likely to want to
5438 change. As the scripts themselves are frequently
5439 <tt>conffile</tt>s, modifying them requires that the
5440 administrator merge in their changes each time the package
5441 is upgraded and the <tt>conffile</tt> changes. To ease
5442 the burden on the system administrator, such configurable
5443 values should not be placed directly in the script.
5444 Instead, they should be placed in a file in
5445 <file>/etc/default</file>, which typically will have the same
5446 base name as the <file>init.d</file> script. This extra file
5447 should be sourced by the script when the script runs. It
5448 must contain only variable settings and comments in POSIX
5449 <prgn>sh</prgn> format. It may either be a
5450 <tt>conffile</tt> or a configuration file maintained by
5451 the package maintainer scripts. See <ref id="config-files">
5456 To ensure that vital configurable values are always
5457 available, the <file>init.d</file> script should set default
5458 values for each of the shell variables it uses, either
5459 before sourcing the <file>/etc/default/</file> file or
5460 afterwards using something like the <tt>:
5461 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5462 script must behave sensibly and not fail if the
5463 <file>/etc/default</file> file is deleted.
5468 <heading>Interfacing with the initscript system</heading>
5471 Maintainers should use the abstraction layer provided by
5472 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5473 programs to deal with initscripts in their packages'
5474 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5475 and <prgn>postrm</prgn>.
5479 Directly managing the /etc/rc?.d links and directly
5480 invoking the <file>/etc/init.d/</file> initscripts should
5481 be done only by packages providing the initscript
5482 subsystem (such as <prgn>sysv-rc</prgn> and
5483 <prgn>file-rc</prgn>).
5487 <heading>Managing the links</heading>
5490 The program <prgn>update-rc.d</prgn> is provided for
5491 package maintainers to arrange for the proper creation and
5492 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5493 or their functional equivalent if another method is being
5494 used. This may be used by maintainers in their packages'
5495 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5499 You must not include any <file>/etc/rc<var>n</var>.d</file>
5500 symbolic links in the actual archive or manually create or
5501 remove the symbolic links in maintainer scripts; you must
5502 use the <prgn>update-rc.d</prgn> program instead. (The
5503 former will fail if an alternative method of maintaining
5504 runlevel information is being used.) You must not include
5505 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5506 in the archive either. (Only the <tt>sysvinit</tt>
5511 By default <prgn>update-rc.d</prgn> will start services in
5512 each of the multi-user state runlevels (2, 3, 4, and 5)
5513 and stop them in the halt runlevel (0), the single-user
5514 runlevel (1) and the reboot runlevel (6). The system
5515 administrator will have the opportunity to customize
5516 runlevels by simply adding, moving, or removing the
5517 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5518 symbolic links are being used, or by modifying
5519 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5524 To get the default behavior for your package, put in your
5525 <prgn>postinst</prgn> script
5526 <example compact="compact">
5527 update-rc.d <var>package</var> defaults
5529 and in your <prgn>postrm</prgn>
5530 <example compact="compact">
5531 if [ "$1" = purge ]; then
5532 update-rc.d <var>package</var> remove
5534 </example>. Note that if your package changes runlevels
5535 or priority, you may have to remove and recreate the links,
5536 since otherwise the old links may persist. Refer to the
5537 documentation of <prgn>update-rc.d</prgn>.
5541 This will use a default sequence number of 20. If it does
5542 not matter when or in which order the <file>init.d</file>
5543 script is run, use this default. If it does, then you
5544 should talk to the maintainer of the <prgn>sysvinit</prgn>
5545 package or post to <tt>debian-devel</tt>, and they will
5546 help you choose a number.
5550 For more information about using <tt>update-rc.d</tt>,
5551 please consult its manpage <manref name="update-rc.d"
5557 <heading>Running initscripts</heading>
5559 The program <prgn>invoke-rc.d</prgn> is provided to make
5560 it easier for package maintainers to properly invoke an
5561 initscript, obeying runlevel and other locally-defined
5562 constraints that might limit a package's right to start,
5563 stop and otherwise manage services. This program may be
5564 used by maintainers in their packages' scripts.
5568 The use of <prgn>invoke-rc.d</prgn> to invoke the
5569 <file>/etc/init.d/*</file> initscripts is strongly
5570 recommended<footnote>
5571 In the future, the use of invoke-rc.d to invoke
5572 initscripts shall be made mandatory. Maintainers are
5573 advised to switch to invoke-rc.d as soon as
5575 </footnote>, instead of calling them directly.
5579 By default, <prgn>invoke-rc.d</prgn> will pass any
5580 action requests (start, stop, reload, restart...) to the
5581 <file>/etc/init.d</file> script, filtering out requests
5582 to start or restart a service out of its intended
5587 Most packages will simply need to change:
5588 <example compact="compact">/etc/init.d/<package>
5589 <action></example> in their <prgn>postinst</prgn>
5590 and <prgn>prerm</prgn> scripts to:
5591 <example compact="compact">
5592 if command -v invoke-rc.d >/dev/null 2>&1; then
5593 invoke-rc.d <var>package</var> <action>
5595 /etc/init.d/<var>package</var> <action>
5601 A package should register its initscript services using
5602 <prgn>update-rc.d</prgn> before it tries to invoke them
5603 using <prgn>invoke-rc.d</prgn>. Invocation of
5604 unregistered services may fail.
5608 For more information about using
5609 <prgn>invoke-rc.d</prgn>, please consult its manpage
5610 <manref name="invoke-rc.d" section="8">.
5616 <heading>Boot-time initialization</heading>
5619 There used to be another directory, <file>/etc/rc.boot</file>,
5620 which contained scripts which were run once per machine
5621 boot. This has been deprecated in favour of links from
5622 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5623 described in <ref id="/etc/init.d">. Packages must not
5624 place files in <file>/etc/rc.boot</file>.
5629 <heading>Example</heading>
5632 The <prgn>bind</prgn> DNS (nameserver) package wants to
5633 make sure that the nameserver is running in multiuser
5634 runlevels, and is properly shut down with the system. It
5635 puts a script in <file>/etc/init.d</file>, naming the script
5636 appropriately <tt>bind</tt>. As you can see, the script
5637 interprets the argument <tt>reload</tt> to send the
5638 nameserver a <tt>HUP</tt> signal (causing it to reload its
5639 configuration); this way the system administrator can say
5640 <tt>/etc/init.d/bind reload</tt> to reload the name
5641 server. The script has one configurable value, which can
5642 be used to pass parameters to the named program at
5643 startup; this value is read from
5644 <file>/etc/default/bind</file> (see below).
5648 <example compact="compact">
5651 # Original version by Robert Leslie
5652 # <rob@mars.org>, edited by iwj and cs
5654 test -x /usr/sbin/named || exit 0
5656 # Source defaults file.
5658 if [ -f /etc/default/bind ]; then
5665 echo -n "Starting domain name service: named"
5666 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5671 echo -n "Stopping domain name service: named"
5672 start-stop-daemon --stop --quiet \
5673 --pidfile /var/run/named.pid --exec /usr/sbin/named
5677 echo -n "Restarting domain name service: named"
5678 start-stop-daemon --stop --quiet --oknodo \
5679 --pidfile /var/run/named.pid --exec /usr/sbin/named
5680 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5684 force-reload|reload)
5685 echo -n "Reloading configuration of domain name service: named"
5686 start-stop-daemon --stop --signal 1 --quiet \
5687 --pidfile /var/run/named.pid --exec /usr/sbin/named
5691 echo "Usage: /etc/init.d/bind " \
5692 " {start|stop|restart|reload|force-reload}" >&2
5702 Complementing the above init script is a configuration
5703 file <file>/etc/default/bind</file>, which contains
5704 configurable parameters used by the script. This would be
5705 created by the <prgn>postinst</prgn> script if it was not
5706 already present, and removed on purge by the
5707 <prgn>postrm</prgn> script.
5708 <example compact="compact">
5709 # Specified parameters to pass to named. See named(8).
5710 # You may uncomment the following line, and edit to taste.
5716 Another example on which you can base your
5717 <file>/etc/init.d</file> scripts is found in
5718 <file>/etc/init.d/skeleton</file>.
5722 If this package is happy with the default setup from
5723 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5724 and having named running in all runlevels, it can say in
5725 its <prgn>postinst</prgn>:
5726 <example compact="compact">
5727 update-rc.d bind defaults >/dev/null
5729 And in its <prgn>postrm</prgn>, to remove the links when the
5731 <example compact="compact">
5732 if [ "$1" = purge ]; then
5733 update-rc.d bind remove >/dev/null
5741 <heading>Console messages from <file>init.d</file> scripts</heading>
5744 This section describes the formats to be used for messages
5745 written to standard output by the <file>/etc/init.d</file>
5746 scripts. The intent is to improve the consistency of
5747 Debian's startup and shutdown look and feel. For this
5748 reason, please look very carefully at the details. We want
5749 the messages to have the same format in terms of wording,
5750 spaces, punctuation and case of letters.
5754 Here is a list of overall rules that you should use when you
5755 create output messages. They can be useful if you have a
5756 non-standard message that is not covered specifically in the
5763 Every message should fit in one line (fewer than 80
5764 characters), start with a capital letter and end with
5765 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5769 If you want to express that the computer is working on
5770 something (that is, performing a specific task, not
5771 starting or stopping a program), we use an "ellipsis"
5772 (three dots: <tt>...</tt>). Note that we don't insert
5773 spaces before or after the dots. If the task has been
5774 completed we write <tt>done.</tt> and a line feed.
5778 Design your messages as if the computer is telling you
5779 what he is doing (let him be polite :-), but don't
5780 mention "him" directly. For example, if you think of
5782 <example compact="compact">
5783 I'm starting network daemons: nfsd mountd.
5786 <example compact="compact">
5787 Starting network daemons: nfsd mountd.
5794 There are standard message formats for the following
5795 situations. They should be used by the <tt>init.d</tt>
5802 <p>When daemons are started</p>
5805 If your script starts one or more daemons, the output
5806 should look like this (a single line, no leading
5808 <example compact="compact">
5809 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5811 The <var>description</var> should describe the
5812 subsystem the daemon or set of daemons are part of,
5813 while <var>daemon-1</var> up to <var>daemon-n</var>
5814 denote each daemon's name (typically the file name of
5819 For example, the output of <file>/etc/init.d/lpd</file>
5821 <example compact="compact">
5822 Starting printer spooler: lpd.
5827 This can be achieved by saying
5828 <example compact="compact">
5829 echo -n "Starting printer spooler: lpd"
5830 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5833 in the script. If you have more than one daemon to
5834 start, you should do the following:
5835 <example compact="compact">
5836 echo -n "Starting remote file system services:"
5837 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5838 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5839 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5842 This makes it possible for the user to see what takes
5843 so long and when the final daemon has been started.
5844 You should be careful where to put spaces: in the
5845 example above the system administrator can easily
5846 comment out a line if he don't wants to start a
5847 specific daemon, while the displayed message still
5853 <p>When a system parameter is being set</p>
5856 If you have to set up different system parameters
5857 during the system boot, you should use this format:
5858 <example compact="compact">
5859 Setting <var>parameter</var> to "<var>value</var>".
5864 You can use a statement such as the following to get
5866 <example compact="compact">
5867 echo "Setting DNS domainname to \"$domainname\"."
5872 Note that the same symbol (<tt>"</tt>) is used for the left
5873 and right quotation marks. A grave accent (<tt>`</tt>) is
5874 not a quote character; neither is an apostrophe
5880 <p>When a daemon is stopped or restarted</p>
5883 When you stop or restart a daemon, you should issue a
5884 message identical to the startup message, except that
5885 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5886 or <tt>Restarting</tt> respectively.
5890 For example, stopping the printer daemon will like
5892 <example compact="compact">
5893 Stopping printer spooler: lpd.
5899 <p>When something is executed</p>
5902 There are several examples where you have to run a
5903 program at system startup or shutdown to perform a
5904 specific task, for example, setting the system's clock
5905 using <prgn>netdate</prgn> or killing all processes
5906 when the system shuts down. Your message should look
5908 <example compact="compact">
5909 Doing something very useful...done.
5911 You should print the <tt>done.</tt> immediately after
5912 the job has been completed, so that the user is
5913 informed why she has to wait. You can get this
5915 <example compact="compact">
5916 echo -n "Doing something very useful..."
5925 <p>When the configuration is reloaded</p>
5928 When a daemon is forced to reload its configuration
5929 files you should use the following format:
5930 <example compact="compact">
5931 Reloading <var>description</var> configuration...done.
5933 where <var>description</var> is the same as in the
5934 daemon starting message.
5942 <heading>Cron jobs</heading>
5945 Packages must not modify the configuration file
5946 <file>/etc/crontab</file>, and they must not modify the files in
5947 <file>/var/spool/cron/crontabs</file>.</p>
5950 If a package wants to install a job that has to be executed
5951 via cron, it should place a file with the name of the
5952 package in one or more of the following directories:
5953 <example compact="compact">
5958 As these directory names imply, the files within them are
5959 executed on a daily, weekly, or monthly basis,
5960 respectively. The exact times are listed in
5961 <file>/etc/crontab</file>.</p>
5964 All files installed in any of these directories must be
5965 scripts (e.g., shell scripts or Perl scripts) so that they
5966 can easily be modified by the local system administrator.
5967 In addition, they should be treated as configuration
5972 If a certain job has to be executed more frequently than
5973 daily, the package should install a file
5974 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5975 same syntax as <file>/etc/crontab</file> and is processed by
5976 <prgn>cron</prgn> automatically. The file must also be
5977 treated as a configuration file. (Note that entries in the
5978 <file>/etc/cron.d</file> directory are not handled by
5979 <prgn>anacron</prgn>. Thus, you should only use this
5980 directory for jobs which may be skipped if the system is not
5984 The scripts or crontab entries in these directories should
5985 check if all necessary programs are installed before they
5986 try to execute them. Otherwise, problems will arise when a
5987 package was removed but not purged since configuration files
5988 are kept on the system in this situation.</p>
5992 <heading>Menus</heading>
5995 The Debian <tt>menu</tt> package provides a standard
5996 interface between packages providing applications and
5997 documents, and <em>menu programs</em> (either X window
5998 managers or text-based menu programs such as
5999 <prgn>pdmenu</prgn>).
6003 All packages that provide applications that need not be
6004 passed any special command line arguments for normal
6005 operation should register a menu entry for those
6006 applications, so that users of the <tt>menu</tt> package
6007 will automatically get menu entries in their window
6008 managers, as well in shells like <tt>pdmenu</tt>.
6012 Menu entries should follow the current menu policy.
6016 The menu policy can be found in the <tt>menu-policy</tt>
6017 files in the <tt>debian-policy</tt> package.
6018 It is also available from the Debian web mirrors at
6019 <tt><url name="/doc/packaging-manuals/menu-policy/"
6020 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
6021 and from the Debian archive mirrors at
6022 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
6023 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
6027 Please also refer to the <em>Debian Menu System</em>
6028 documentation that comes with the <tt>menu</tt> package for
6029 information about how to register your applications and web
6035 <heading>Multimedia handlers</heading>
6038 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6039 is a mechanism for encoding files and data streams and
6040 providing meta-information about them, in particular their
6041 type (e.g. audio or video) and format (e.g. PNG, HTML,
6046 Registration of MIME type handlers allows programs like mail
6047 user agents and web browsers to invoke these handlers to
6048 view, edit or display MIME types they don't support directly.
6052 Packages which provide the ability to view/show/play,
6053 compose, edit or print MIME types should register themselves
6054 as such following the current MIME support policy.
6058 The MIME support policy can be found in the <tt>mime-policy</tt>
6059 files in the <tt>debian-policy</tt> package.
6060 It is also available from the Debian web mirrors at
6061 <tt><url name="/doc/packaging-manuals/mime-policy/"
6062 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
6063 and from the Debian archive mirrors at
6064 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
6065 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
6071 <heading>Keyboard configuration</heading>
6074 To achieve a consistent keyboard configuration so that all
6075 applications interpret a keyboard event the same way, all
6076 programs in the Debian distribution must be configured to
6077 comply with the following guidelines.
6081 The following keys must have the specified interpretations:
6084 <tag><tt><--</tt></tag>
6085 <item>delete the character to the left of the cursor</item>
6087 <tag><tt>Delete</tt></tag>
6088 <item>delete the character to the right of the cursor</item>
6090 <tag><tt>Control+H</tt></tag>
6091 <item>emacs: the help prefix</item>
6094 The interpretation of any keyboard events should be
6095 independent of the terminal that is used, be it a virtual
6096 console, an X terminal emulator, an rlogin/telnet session,
6101 The following list explains how the different programs
6102 should be set up to achieve this:
6108 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6112 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6116 X translations are set up to make
6117 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6118 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6119 is the vt220 escape code for the "delete character"
6120 key). This must be done by loading the X resources
6121 using <prgn>xrdb</prgn> on all local X displays, not
6122 using the application defaults, so that the
6123 translation resources used correspond to the
6124 <prgn>xmodmap</prgn> settings.
6128 The Linux console is configured to make
6129 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6130 generate <tt>ESC [ 3 ~</tt>.
6134 X applications are configured so that <tt><</tt>
6135 deletes left, and <tt>Delete</tt> deletes right. Motif
6136 applications already work like this.
6140 Terminals should have <tt>stty erase ^?</tt> .
6144 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6145 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6146 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6150 Emacs is programmed to map <tt>KB_Backspace</tt> or
6151 the <tt>stty erase</tt> character to
6152 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6153 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6154 <tt>^H</tt> to <tt>help</tt> as always.
6158 Other applications use the <tt>stty erase</tt>
6159 character and <tt>kdch1</tt> for the two delete keys,
6160 with ASCII DEL being "delete previous character" and
6161 <tt>kdch1</tt> being "delete character under
6169 This will solve the problem except for the following
6176 Some terminals have a <tt><--</tt> key that cannot
6177 be made to produce anything except <tt>^H</tt>. On
6178 these terminals Emacs help will be unavailable on
6179 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6180 character takes precedence in Emacs, and has been set
6181 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6182 available) can be used instead.
6186 Some operating systems use <tt>^H</tt> for <tt>stty
6187 erase</tt>. However, modern telnet versions and all
6188 rlogin versions propagate <tt>stty</tt> settings, and
6189 almost all UNIX versions honour <tt>stty erase</tt>.
6190 Where the <tt>stty</tt> settings are not propagated
6191 correctly, things can be made to work by using
6192 <tt>stty</tt> manually.
6196 Some systems (including previous Debian versions) use
6197 <prgn>xmodmap</prgn> to arrange for both
6198 <tt><--</tt> and <tt>Delete</tt> to generate
6199 <tt>KB_Delete</tt>. We can change the behavior of
6200 their X clients using the same X resources that we use
6201 to do it for our own clients, or configure our clients
6202 using their resources when things are the other way
6203 around. On displays configured like this
6204 <tt>Delete</tt> will not work, but <tt><--</tt>
6209 Some operating systems have different <tt>kdch1</tt>
6210 settings in their <tt>terminfo</tt> database for
6211 <tt>xterm</tt> and others. On these systems the
6212 <tt>Delete</tt> key will not work correctly when you
6213 log in from a system conforming to our policy, but
6214 <tt><--</tt> will.
6221 <heading>Environment variables</heading>
6224 A program must not depend on environment variables to get
6225 reasonable defaults. (That's because these environment
6226 variables would have to be set in a system-wide
6227 configuration file like <file>/etc/profile</file>, which is not
6228 supported by all shells.)
6232 If a program usually depends on environment variables for its
6233 configuration, the program should be changed to fall back to
6234 a reasonable default configuration if these environment
6235 variables are not present. If this cannot be done easily
6236 (e.g., if the source code of a non-free program is not
6237 available), the program must be replaced by a small
6238 "wrapper" shell script which sets the environment variables
6239 if they are not already defined, and calls the original program.
6243 Here is an example of a wrapper script for this purpose:
6245 <example compact="compact">
6247 BAR=${BAR:-/var/lib/fubar}
6249 exec /usr/lib/foo/foo "$@"
6254 Furthermore, as <file>/etc/profile</file> is a configuration
6255 file of the <prgn>base-files</prgn> package, other packages must
6256 not put any environment variables or other commands into that
6265 <heading>Files</heading>
6268 <heading>Binaries</heading>
6271 Two different packages must not install programs with
6272 different functionality but with the same filenames. (The
6273 case of two programs having the same functionality but
6274 different implementations is handled via "alternatives" or
6275 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6276 <ref id="conflicts"> respectively.) If this case happens,
6277 one of the programs must be renamed. The maintainers should
6278 report this to the <tt>debian-devel</tt> mailing list and
6279 try to find a consensus about which program will have to be
6280 renamed. If a consensus cannot be reached, <em>both</em>
6281 programs must be renamed.
6285 By default, when a package is being built, any binaries
6286 created should include debugging information, as well as
6287 being compiled with optimization. You should also turn on
6288 as many reasonable compilation warnings as possible; this
6289 makes life easier for porters, who can then look at build
6290 logs for possible problems. For the C programming language,
6291 this means the following compilation parameters should be
6293 <example compact="compact">
6295 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6297 install -s # (or use strip on the files in debian/tmp)
6302 Note that by default all installed binaries should be stripped,
6303 either by using the <tt>-s</tt> flag to
6304 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6305 the binaries after they have been copied into
6306 <file>debian/tmp</file> but before the tree is made into a
6311 Although binaries in the build tree should be compiled with
6312 debugging information by default, it can often be difficult
6313 to debug programs if they are also subjected to compiler
6314 optimization. For this reason, it is recommended to support
6315 the standardized environment
6316 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6317 contain several flags to change how a package is compiled
6325 The presence of this string means that the package
6326 should be compiled with a minimum of optimization.
6327 For C programs, it is best to add <tt>-O0</tt>
6328 to <tt>CFLAGS</tt> (although this is usually the
6329 default). Some programs might fail to build or run at
6330 this level of optimization; it may be necessary to
6331 use <tt>-O1</tt>, for example.
6335 This string means that the debugging symbols should
6336 not be stripped from the binary during installation,
6337 so that debugging information may be included in the package.
6343 The following makefile snippet is an example of how one may
6344 implement the build options; you will probably have to
6345 massage this example in order to make it work for your
6347 <example compact="compact">
6350 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6351 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6352 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6353 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6355 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6360 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6361 INSTALL_PROGRAM += -s
6367 It is up to the package maintainer to decide what
6368 compilation options are best for the package. Certain
6369 binaries (such as computationally-intensive programs) will
6370 function better with certain flags (<tt>-O3</tt>, for
6371 example); feel free to use them. Please use good judgment
6372 here. Don't use flags for the sake of it; only use them
6373 if there is good reason to do so. Feel free to override
6374 the upstream author's ideas about which compilation
6375 options are best: they are often inappropriate for our
6381 <sect id="libraries">
6382 <heading>Libraries</heading>
6385 The shared version of a library must be compiled with
6386 <tt>-fPIC</tt>, and the static version must not be. In other
6387 words, each source unit (<tt>*.c</tt>, for example, for C files)
6388 will need to be compiled twice.
6392 You must specify the gcc option <tt>-D_REENTRANT</tt>
6393 when building a library (either static or shared) to make
6394 the library compatible with LinuxThreads.
6398 Although not enforced by the build tools, shared libraries
6399 must be linked against all libraries that they use symbols from
6400 in the same way that binaries are. This ensures the correct
6401 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6402 system and guarantees that all libraries can be safely opened
6403 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6404 option <tt>-Wl,-z,defs</tt> when building a shared library.
6405 Since this option enforces symbol resolution at build time,
6406 a missing library reference will be caught early as a fatal
6411 All installed shared libraries should be stripped with
6412 <example compact="compact">
6413 strip --strip-unneeded <var>your-lib</var>
6415 (The option <tt>--strip-unneeded</tt> makes
6416 <prgn>strip</prgn> remove only the symbols which aren't
6417 needed for relocation processing.) Shared libraries can
6418 function perfectly well when stripped, since the symbols for
6419 dynamic linking are in a separate part of the ELF object
6421 You might also want to use the options
6422 <tt>--remove-section=.comment</tt> and
6423 <tt>--remove-section=.note</tt> on both shared libraries
6424 and executables, and <tt>--strip-debug</tt> on static
6430 Note that under some circumstances it may be useful to
6431 install a shared library unstripped, for example when
6432 building a separate package to support debugging.
6436 Shared object files (often <file>.so</file> files) that are not
6437 public libraries, that is, they are not meant to be linked
6438 to by third party executables (binaries of other packages),
6439 should be installed in subdirectories of the
6440 <file>/usr/lib</file> directory. Such files are exempt from the
6441 rules that govern ordinary shared libraries, except that
6442 they must not be installed executable and should be
6444 A common example are the so-called "plug-ins",
6445 internal shared objects that are dynamically loaded by
6446 programs using <manref name="dlopen" section="3">.
6451 Packages containing shared libraries that may be linked to
6452 by other packages' binaries, but which for some
6453 <em>compelling</em> reason can not be installed in
6454 <file>/usr/lib</file> directory, may install the shared library
6455 files in subdirectories of the <file>/usr/lib</file> directory,
6456 in which case they should arrange to add that directory in
6457 <file>/etc/ld.so.conf</file> in the package's post-installation
6458 script, and remove it in the package's post-removal script.
6462 An ever increasing number of packages are using
6463 <prgn>libtool</prgn> to do their linking. The latest GNU
6464 libtools (>= 1.3a) can take advantage of the metadata in the
6465 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6466 files). The main advantage of <prgn>libtool</prgn>'s
6467 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6468 store and subsequently access metadata with respect to the
6469 libraries it builds. <prgn>libtool</prgn> will search for
6470 those files, which contain a lot of useful information about
6471 a library (such as library dependency information for static
6472 linking). Also, they're <em>essential</em> for programs
6473 using <tt>libltdl</tt>.<footnote>
6474 Although <prgn>libtool</prgn> is fully capable of
6475 linking against shared libraries which don't have
6476 <tt>.la</tt> files, as it is a mere shell script it can
6477 add considerably to the build time of a
6478 <prgn>libtool</prgn>-using package if that shell script
6479 has to derive all this information from first principles
6480 for each library every time it is linked. With the
6481 advent of <prgn>libtool</prgn> version 1.4 (and to a
6482 lesser extent <prgn>libtool</prgn> version 1.3), the
6483 <file>.la</file> files also store information about
6484 inter-library dependencies which cannot necessarily be
6485 derived after the <file>.la</file> file is deleted.
6490 Packages that use <prgn>libtool</prgn> to create shared
6491 libraries should include the <file>.la</file> files in the
6492 <tt>-dev</tt> package, unless the package relies on
6493 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6494 the <tt>.la</tt> files must go in the run-time library
6499 You must make sure that you use only released versions of
6500 shared libraries to build your packages; otherwise other
6501 users will not be able to run your binaries
6502 properly. Producing source packages that depend on
6503 unreleased compilers is also usually a bad
6510 <heading>Shared libraries</heading>
6512 This section has moved to <ref id="sharedlibs">.
6518 <heading>Scripts</heading>
6521 All command scripts, including the package maintainer
6522 scripts inside the package and used by <prgn>dpkg</prgn>,
6523 should have a <tt>#!</tt> line naming the shell to be used
6528 In the case of Perl scripts this should be
6529 <tt>#!/usr/bin/perl</tt>.
6533 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6534 should almost certainly start with <tt>set -e</tt> so that
6535 errors are detected. Every script should use
6536 <tt>set -e</tt> or check the exit status of <em>every</em>
6541 The standard shell interpreter <file>/bin/sh</file> can be a
6542 symbolic link to any POSIX compatible shell, if <tt>echo
6543 -n</tt> does not generate a newline.<footnote>
6544 Debian policy specifies POSIX behavior for
6545 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6546 use in the Linux community (in particular including this
6547 policy, the Linux kernel source, many Debian scripts,
6548 etc.). This <tt>echo -n</tt> mechanism is valid but not
6549 required under POSIX, hence this explicit addition.
6550 Also, rumour has it that this shall be mandated under
6553 Thus, shell scripts specifying <file>/bin/sh</file> as
6554 interpreter should only use POSIX features. If a script
6555 requires non-POSIX features from the shell interpreter, the
6556 appropriate shell must be specified in the first line of the
6557 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6558 depend on the package providing the shell (unless the shell
6559 package is marked "Essential", as in the case of
6564 You may wish to restrict your script to POSIX features when
6565 possible so that it may use <file>/bin/sh</file> as its
6566 interpreter. If your script works with <prgn>dash</prgn>
6567 (originally called <prgn>ash</prgn>), it's probably POSIX
6568 compliant, but if you are in doubt, use
6569 <file>/bin/bash</file>.
6573 Perl scripts should check for errors when making any
6574 system calls, including <tt>open</tt>, <tt>print</tt>,
6575 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6579 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6580 scripting languages. See <em>Csh Programming Considered
6581 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6582 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
6583 If an upstream package comes with <prgn>csh</prgn> scripts
6584 then you must make sure that they start with
6585 <tt>#!/bin/csh</tt> and make your package depend on the
6586 <prgn>c-shell</prgn> virtual package.
6590 Any scripts which create files in world-writeable
6591 directories (e.g., in <file>/tmp</file>) must use a
6592 mechanism which will fail if a file with the same name
6597 The Debian base system provides the <prgn>tempfile</prgn>
6598 and <prgn>mktemp</prgn> utilities for use by scripts for
6605 <heading>Symbolic links</heading>
6608 In general, symbolic links within a top-level directory
6609 should be relative, and symbolic links pointing from one
6610 top-level directory into another should be absolute. (A
6611 top-level directory is a sub-directory of the root
6612 directory <file>/</file>.)
6616 In addition, symbolic links should be specified as short as
6617 possible, i.e., link targets like <file>foo/../bar</file> are
6622 Note that when creating a relative link using
6623 <prgn>ln</prgn> it is not necessary for the target of the
6624 link to exist relative to the working directory you're
6625 running <prgn>ln</prgn> from, nor is it necessary to change
6626 directory to the directory where the link is to be made.
6627 Simply include the string that should appear as the target
6628 of the link (this will be a pathname relative to the
6629 directory in which the link resides) as the first argument
6634 For example, in your <prgn>Makefile</prgn> or
6635 <file>debian/rules</file>, you can do things like:
6636 <example compact="compact">
6637 ln -fs gcc $(prefix)/bin/cc
6638 ln -fs gcc debian/tmp/usr/bin/cc
6639 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6640 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6645 A symbolic link pointing to a compressed file should always
6646 have the same file extension as the referenced file. (For
6647 example, if a file <file>foo.gz</file> is referenced by a
6648 symbolic link, the filename of the link has to end with
6649 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6654 <heading>Device files</heading>
6657 Packages must not include device files in the package file
6662 If a package needs any special device files that are not
6663 included in the base system, it must call
6664 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6665 after notifying the user<footnote>
6666 This notification could be done via a (low-priority)
6667 debconf message, or an echo (printf) statement.
6672 Packages must not remove any device files in the
6673 <prgn>postrm</prgn> or any other script. This is left to the
6674 system administrator.
6678 Debian uses the serial devices
6679 <file>/dev/ttyS*</file>. Programs using the old
6680 <file>/dev/cu*</file> devices should be changed to use
6681 <file>/dev/ttyS*</file>.
6685 <sect id="config-files">
6686 <heading>Configuration files</heading>
6689 <heading>Definitions</heading>
6693 <tag>configuration file</tag>
6695 A file that affects the operation of a program, or
6696 provides site- or host-specific information, or
6697 otherwise customizes the behavior of a program.
6698 Typically, configuration files are intended to be
6699 modified by the system administrator (if needed or
6700 desired) to conform to local policy or to provide
6701 more useful site-specific behavior.
6704 <tag><tt>conffile</tt></tag>
6706 A file listed in a package's <tt>conffiles</tt>
6707 file, and is treated specially by <prgn>dpkg</prgn>
6708 (see <ref id="configdetails">).
6714 The distinction between these two is important; they are
6715 not interchangeable concepts. Almost all
6716 <tt>conffile</tt>s are configuration files, but many
6717 configuration files are not <tt>conffiles</tt>.
6721 Note that a script that embeds configuration information
6722 (such as most of the files in <file>/etc/default</file> and
6723 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6724 configuration file and should be treated as such.
6729 <heading>Location</heading>
6732 Any configuration files created or used by your package
6733 must reside in <file>/etc</file>. If there are several,
6734 consider creating a subdirectory of <file>/etc</file>
6735 named after your package.
6739 If your package creates or uses configuration files
6740 outside of <file>/etc</file>, and it is not feasible to modify
6741 the package to use <file>/etc</file> directly, put the files
6742 in <file>/etc</file> and create symbolic links to those files
6743 from the location that the package requires.
6748 <heading>Behavior</heading>
6751 Configuration file handling must conform to the following
6753 <list compact="compact">
6755 local changes must be preserved during a package
6759 configuration files must be preserved when the
6760 package is removed, and only deleted when the
6767 The easy way to achieve this behavior is to make the
6768 configuration file a <tt>conffile</tt>. This is
6769 appropriate only if it is possible to distribute a default
6770 version that will work for most installations, although
6771 some system administrators may choose to modify it. This
6772 implies that the default version will be part of the
6773 package distribution, and must not be modified by the
6774 maintainer scripts during installation (or at any other
6779 In order to ensure that local changes are preserved
6780 correctly, no package may contain or make hard links to
6781 conffiles.<footnote>
6782 Rationale: There are two problems with hard links.
6783 The first is that some editors break the link while
6784 editing one of the files, so that the two files may
6785 unwittingly become unlinked and different. The second
6786 is that <prgn>dpkg</prgn> might break the hard link
6787 while upgrading <tt>conffile</tt>s.
6792 The other way to do it is via the maintainer scripts. In
6793 this case, the configuration file must not be listed as a
6794 <tt>conffile</tt> and must not be part of the package
6795 distribution. If the existence of a file is required for
6796 the package to be sensibly configured it is the
6797 responsibility of the package maintainer to provide
6798 maintainer scripts which correctly create, update and
6799 maintain the file and remove it on purge. (See <ref
6800 id="maintainerscripts"> for more information.) These
6801 scripts must be idempotent (i.e., must work correctly if
6802 <prgn>dpkg</prgn> needs to re-run them due to errors
6803 during installation or removal), must cope with all the
6804 variety of ways <prgn>dpkg</prgn> can call maintainer
6805 scripts, must not overwrite or otherwise mangle the user's
6806 configuration without asking, must not ask unnecessary
6807 questions (particularly during upgrades), and otherwise be
6812 The scripts are not required to configure every possible
6813 option for the package, but only those necessary to get
6814 the package running on a given system. Ideally the
6815 sysadmin should not have to do any configuration other
6816 than that done (semi-)automatically by the
6817 <prgn>postinst</prgn> script.
6821 A common practice is to create a script called
6822 <file><var>package</var>-configure</file> and have the
6823 package's <prgn>postinst</prgn> call it if and only if the
6824 configuration file does not already exist. In certain
6825 cases it is useful for there to be an example or template
6826 file which the maintainer scripts use. Such files should
6827 be in <file>/usr/share/<var>package</var></file> or
6828 <file>/usr/lib/<var>package</var></file> (depending on whether
6829 they are architecture-independent or not). There should
6830 be symbolic links to them from
6831 <file>/usr/share/doc/<var>package</var>/examples</file> if
6832 they are examples, and should be perfectly ordinary
6833 <prgn>dpkg</prgn>-handled files (<em>not</em>
6834 configuration files).
6838 These two styles of configuration file handling must
6839 not be mixed, for that way lies madness:
6840 <prgn>dpkg</prgn> will ask about overwriting the file
6841 every time the package is upgraded.
6846 <heading>Sharing configuration files</heading>
6849 Packages which specify the same file as a
6850 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6851 with each other. (This is an instance of the general rule
6852 about not sharing files. Note that neither alternatives
6853 nor diversions are likely to be appropriate in this case;
6854 in particular, <prgn>dpkg</prgn> does not handle diverted
6855 <tt>conffile</tt>s well.)
6859 The maintainer scripts must not alter a <tt>conffile</tt>
6860 of <em>any</em> package, including the one the scripts
6865 If two or more packages use the same configuration file
6866 and it is reasonable for both to be installed at the same
6867 time, one of these packages must be defined as
6868 <em>owner</em> of the configuration file, i.e., it will be
6869 the package which handles that file as a configuration
6870 file. Other packages that use the configuration file must
6871 depend on the owning package if they require the
6872 configuration file to operate. If the other package will
6873 use the configuration file if present, but is capable of
6874 operating without it, no dependency need be declared.
6878 If it is desirable for two or more related packages to
6879 share a configuration file <em>and</em> for all of the
6880 related packages to be able to modify that configuration
6881 file, then the following should be done:
6882 <enumlist compact="compact">
6884 One of the related packages (the "owning" package)
6885 will manage the configuration file with maintainer
6886 scripts as described in the previous section.
6889 The owning package should also provide a program
6890 that the other packages may use to modify the
6894 The related packages must use the provided program
6895 to make any desired modifications to the
6896 configuration file. They should either depend on
6897 the core package to guarantee that the configuration
6898 modifier program is available or accept gracefully
6899 that they cannot modify the configuration file if it
6900 is not. (This is in addition to the fact that the
6901 configuration file may not even be present in the
6908 Sometimes it's appropriate to create a new package which
6909 provides the basic infrastructure for the other packages
6910 and which manages the shared configuration files. (The
6911 <tt>sgml-base</tt> package is a good example.)
6916 <heading>User configuration files ("dotfiles")</heading>
6919 The files in <file>/etc/skel</file> will automatically be
6920 copied into new user accounts by <prgn>adduser</prgn>.
6921 No other program should reference the files in
6922 <file>/etc/skel</file>.
6926 Therefore, if a program needs a dotfile to exist in
6927 advance in <file>$HOME</file> to work sensibly, that dotfile
6928 should be installed in <file>/etc/skel</file> and treated as a
6933 However, programs that require dotfiles in order to
6934 operate sensibly are a bad thing, unless they do create
6935 the dotfiles themselves automatically.
6939 Furthermore, programs should be configured by the Debian
6940 default installation to behave as closely to the upstream
6941 default behaviour as possible.
6945 Therefore, if a program in a Debian package needs to be
6946 configured in some way in order to operate sensibly, that
6947 should be done using a site-wide configuration file placed
6948 in <file>/etc</file>. Only if the program doesn't support a
6949 site-wide default configuration and the package maintainer
6950 doesn't have time to add it may a default per-user file be
6951 placed in <file>/etc/skel</file>.
6955 <file>/etc/skel</file> should be as empty as we can make it.
6956 This is particularly true because there is no easy (or
6957 necessarily desirable) mechanism for ensuring that the
6958 appropriate dotfiles are copied into the accounts of
6959 existing users when a package is installed.
6965 <heading>Log files</heading>
6967 Log files should usually be named
6968 <file>/var/log/<var>package</var>.log</file>. If you have many
6969 log files, or need a separate directory for permission
6970 reasons (<file>/var/log</file> is writable only by
6971 <file>root</file>), you should usually create a directory named
6972 <file>/var/log/<var>package</var></file> and place your log
6977 Log files must be rotated occasionally so that they don't
6978 grow indefinitely; the best way to do this is to drop a log
6979 rotation configuration file into the directory
6980 <file>/etc/logrotate.d</file> and use the facilities provided by
6981 logrotate.<footnote>
6983 The traditional approach to log files has been to set up
6984 <em>ad hoc</em> log rotation schemes using simple shell
6985 scripts and cron. While this approach is highly
6986 customizable, it requires quite a lot of sysadmin work.
6987 Even though the original Debian system helped a little
6988 by automatically installing a system which can be used
6989 as a template, this was deemed not enough.
6993 The use of <prgn>logrotate</prgn>, a program developed
6994 by Red Hat, is better, as it centralizes log management.
6995 It has both a configuration file
6996 (<file>/etc/logrotate.conf</file>) and a directory where
6997 packages can drop their individual log rotation
6998 configurations (<file>/etc/logrotate.d</file>).
7001 Here is a good example for a logrotate config
7002 file (for more information see <manref name="logrotate"
7004 <example compact="compact">
7005 /var/log/foo/*.log {
7010 /etc/init.d/foo force-reload
7014 This rotates all files under <file>/var/log/foo</file>, saves 12
7015 compressed generations, and forces the daemon to reload its
7016 configuration information after the log rotation.
7020 Log files should be removed when the package is
7021 purged (but not when it is only removed). This should be
7022 done by the <prgn>postrm</prgn> script when it is called
7023 with the argument <tt>purge</tt> (see <ref
7024 id="removedetails">).
7029 <heading>Permissions and owners</heading>
7032 The rules in this section are guidelines for general use.
7033 If necessary you may deviate from the details below.
7034 However, if you do so you must make sure that what is done
7035 is secure and you should try to be as consistent as possible
7036 with the rest of the system. You should probably also
7037 discuss it on <prgn>debian-devel</prgn> first.
7041 Files should be owned by <tt>root.root</tt>, and made
7042 writable only by the owner and universally readable (and
7043 executable, if appropriate), that is mode 644 or 755.
7047 Directories should be mode 755 or (for group-writability)
7048 mode 2775. The ownership of the directory should be
7049 consistent with its mode: if a directory is mode 2775, it
7050 should be owned by the group that needs write access to
7055 Setuid and setgid executables should be mode 4755 or 2755
7056 respectively, and owned by the appropriate user or group.
7057 They should not be made unreadable (modes like 4711 or
7058 2711 or even 4111); doing so achieves no extra security,
7059 because anyone can find the binary in the freely available
7060 Debian package; it is merely inconvenient. For the same
7061 reason you should not restrict read or execute permissions
7062 on non-set-id executables.
7066 Some setuid programs need to be restricted to particular
7067 sets of users, using file permissions. In this case they
7068 should be owned by the uid to which they are set-id, and by
7069 the group which should be allowed to execute them. They
7070 should have mode 4754; again there is no point in making
7071 them unreadable to those users who must not be allowed to
7076 It is possible to arrange that the system administrator can
7077 reconfigure the package to correspond to their local
7078 security policy by changing the permissions on a binary:
7079 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7080 described below.<footnote>
7081 Ordinary files installed by <prgn>dpkg</prgn> (as
7082 opposed to <tt>conffile</tt>s and other similar objects)
7083 normally have their permissions reset to the distributed
7084 permissions when the package is reinstalled. However,
7085 the use of <prgn>dpkg-statoverride</prgn> overrides this
7086 default behaviour. If you use this method, you should
7087 remember to describe <prgn>dpkg-statoverride</prgn> in
7088 the package documentation; being a relatively new
7089 addition to Debian, it is probably not yet well-known.
7091 Another method you should consider is to create a group for
7092 people allowed to use the program(s) and make any setuid
7093 executables executable only by that group.
7097 If you need to create a new user or group for your package
7098 there are two possibilities. Firstly, you may need to
7099 make some files in the binary package be owned by this
7100 user or group, or you may need to compile the user or
7101 group id (rather than just the name) into the binary
7102 (though this latter should be avoided if possible, as in
7103 this case you need a statically allocated id).</p>
7106 If you need a statically allocated id, you must ask for a
7107 user or group id from the <tt>base-passwd</tt> maintainer,
7108 and must not release the package until you have been
7109 allocated one. Once you have been allocated one you must
7110 either make the package depend on a version of the
7111 <tt>base-passwd</tt> package with the id present in
7112 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7113 your package to create the user or group itself with the
7114 correct id (using <tt>adduser</tt>) in its
7115 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7116 the <prgn>postinst</prgn> is to be preferred if it is
7117 possible, otherwise a pre-dependency will be needed on the
7118 <tt>adduser</tt> package.)
7122 On the other hand, the program might be able to determine
7123 the uid or gid from the user or group name at runtime, so
7124 that a dynamically allocated id can be used. In this case
7125 you should choose an appropriate user or group name,
7126 discussing this on <prgn>debian-devel</prgn> and checking
7127 with the <package/base-passwd/ maintainer that it is unique and that
7128 they do not wish you to use a statically allocated id
7129 instead. When this has been checked you must arrange for
7130 your package to create the user or group if necessary using
7131 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7132 <prgn>postinst</prgn> script (again, the latter is to be
7133 preferred if it is possible).
7137 Note that changing the numeric value of an id associated
7138 with a name is very difficult, and involves searching the
7139 file system for all appropriate files. You need to think
7140 carefully whether a static or dynamic id is required, since
7141 changing your mind later will cause problems.
7144 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7146 This section is not intended as policy, but as a
7147 description of the use of <prgn>dpkg-statoverride</prgn>.
7151 <prgn>dpkg-statoverride</prgn> is a replacement for the
7152 deprecated <tt>suidmanager</tt> package. Packages which
7153 previously used <tt>suidmanager</tt> should have a
7154 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7155 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7156 and <tt>suidunregister</tt> should now be simply removed
7157 from the maintainer scripts.
7161 If a system administrator wishes to have a file (or
7162 directory or other such thing) installed with owner and
7163 permissions different from those in the distributed Debian
7164 package, he can use the <prgn>dpkg-statoverride</prgn>
7165 program to instruct <prgn>dpkg</prgn> to use the different
7166 settings every time the file is installed. Thus the
7167 package maintainer should distribute the files with their
7168 normal permissions, and leave it for the system
7169 administrator to make any desired changes. For example, a
7170 daemon which is normally required to be setuid root, but
7171 in certain situations could be used without being setuid,
7172 should be installed setuid in the <tt>.deb</tt>. Then the
7173 local system administrator can change this if they wish.
7174 If there are two standard ways of doing it, the package
7175 maintainer can use <tt>debconf</tt> to find out the
7176 preference, and call <prgn>dpkg-statoverride</prgn> in the
7177 maintainer script if necessary to accommodate the system
7178 administrator's choice.
7182 Given the above, <prgn>dpkg-statoverride</prgn> is
7183 essentially a tool for system administrators and would not
7184 normally be needed in the maintainer scripts. There is
7185 one type of situation, though, where calls to
7186 <prgn>dpkg-statoverride</prgn> would be needed in the
7187 maintainer scripts, and that involves packages which use
7188 dynamically allocated user or group ids. In such a
7189 situation, something like the following idiom can be very
7190 helpful in the package's <prgn>postinst</prgn>, where
7191 <tt>sysuser</tt> is a dynamically allocated id:
7193 for i in /usr/bin/foo /usr/sbin/bar
7195 if ! dpkg-statoverride --list $i >/dev/null
7197 dpkg-statoverride --update --add sysuser root 4755 $i
7201 The corresponding <tt>dpkg-statoverride --remove</tt>
7202 calls can then be made unconditionally when the package is
7210 <chapt id="customized-programs">
7211 <heading>Customized programs</heading>
7213 <sect id="arch-spec">
7214 <heading>Architecture specification strings</heading>
7217 If a program needs to specify an <em>architecture specification
7218 string</em> in some place, the following format should be
7219 used: <var>arch</var>-<var>os</var><footnote>
7220 The following architectures and operating systems are
7221 currently recognised by <prgn>dpkg-architecture</prgn>.
7222 The architecture, <tt><var>arch</var></tt>, is one of
7223 the following: <tt>alpha</tt>, <tt>arm</tt>,
7224 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7225 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7226 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7227 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7228 operating system, <tt><var>os</var></tt>, is one of:
7229 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7230 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7231 reserved for the GNU/Hurd operating system.
7236 Note that we don't want to use
7237 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7238 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7239 since this would make our programs incompatible with other
7240 Linux distributions. We also don't use something like
7241 <tt><var>arch</var>-unknown-linux</tt>, since the
7242 <tt>unknown</tt> does not look very good.
7247 <heading>Daemons</heading>
7250 The configuration files <file>/etc/services</file>,
7251 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7252 by the <prgn>netbase</prgn> package and must not be modified
7257 If a package requires a new entry in one of these files, the
7258 maintainer should get in contact with the
7259 <prgn>netbase</prgn> maintainer, who will add the entries
7260 and release a new version of the <prgn>netbase</prgn>
7265 The configuration file <file>/etc/inetd.conf</file> must not be
7266 modified by the package's scripts except via the
7267 <prgn>update-inetd</prgn> script or the
7268 <file>DebianNet.pm</file> Perl module. See their documentation
7269 for details on how to add entries.
7273 If a package wants to install an example entry into
7274 <file>/etc/inetd.conf</file>, the entry must be preceded with
7275 exactly one hash character (<tt>#</tt>). Such lines are
7276 treated as "commented out by user" by the
7277 <prgn>update-inetd</prgn> script and are not changed or
7278 activated during package updates.
7283 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7287 Some programs need to create pseudo-ttys. This should be done
7288 using Unix98 ptys if the C library supports it. The resulting
7289 program must not be installed setuid root, unless that
7290 is required for other functionality.
7294 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7295 <file>/var/log/lastlog</file> must be installed writeable by
7296 group <tt>utmp</tt>. Programs which need to modify those
7297 files must be installed setgid <tt>utmp</tt>.
7302 <heading>Editors and pagers</heading>
7305 Some programs have the ability to launch an editor or pager
7306 program to edit or display a text document. Since there are
7307 lots of different editors and pagers available in the Debian
7308 distribution, the system administrator and each user should
7309 have the possibility to choose his/her preferred editor and
7314 In addition, every program should choose a good default
7315 editor/pager if none is selected by the user or system
7320 Thus, every program that launches an editor or pager must
7321 use the EDITOR or PAGER environment variable to determine
7322 the editor or pager the user wishes to use. If these
7323 variables are not set, the programs <file>/usr/bin/editor</file>
7324 and <file>/usr/bin/pager</file> should be used, respectively.
7328 These two files are managed through the <prgn>dpkg</prgn>
7329 "alternatives" mechanism. Thus every package providing an
7330 editor or pager must call the
7331 <prgn>update-alternatives</prgn> script to register these
7336 If it is very hard to adapt a program to make use of the
7337 EDITOR or PAGER variables, that program may be configured to
7338 use <file>/usr/bin/sensible-editor</file> and
7339 <file>/usr/bin/sensible-pager</file> as the editor or pager
7340 program respectively. These are two scripts provided in the
7341 Debian base system that check the EDITOR and PAGER variables
7342 and launch the appropriate program, and fall back to
7343 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7344 variable is not set.
7348 A program may also use the VISUAL environment variable to
7349 determine the user's choice of editor. If it exists, it
7350 should take precedence over EDITOR. This is in fact what
7351 <file>/usr/bin/sensible-editor</file> does.
7355 It is not required for a package to depend on
7356 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7357 package to provide such virtual packages.<footnote>
7358 The Debian base system already provides an editor and a
7364 <sect id="web-appl">
7365 <heading>Web servers and applications</heading>
7368 This section describes the locations and URLs that should
7369 be used by all web servers and web applications in the
7376 Cgi-bin executable files are installed in the
7378 <example compact="compact">
7379 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7381 and should be referred to as
7382 <example compact="compact">
7383 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7388 <p>Access to HTML documents</p>
7391 HTML documents for a package are stored in
7392 <file>/usr/share/doc/<var>package</var></file>
7393 and can be referred to as
7394 <example compact="compact">
7395 http://localhost/doc/<var>package</var>/<var>filename</var>
7400 The web server should restrict access to the document
7401 tree so that only clients on the same host can read
7402 the documents. If the web server does not support such
7403 access controls, then it should not provide access at
7404 all, or ask about providing access during installation.
7409 <p>Web Document Root</p>
7412 Web Applications should try to avoid storing files in
7413 the Web Document Root. Instead they should use the
7414 /usr/share/doc/<var>package</var> directory for
7415 documents and register the Web Application via the
7416 menu package. If access to the web document root is
7417 unavoidable then use
7418 <example compact="compact">
7421 as the Document Root. This might be just a symbolic
7422 link to the location where the system administrator
7423 has put the real document root.
7431 <sect id="mail-transport-agents">
7432 <heading>Mail transport, delivery and user agents</heading>
7435 Debian packages which process electronic mail, whether mail
7436 user agents (MUAs) or mail transport agents (MTAs), must
7437 ensure that they are compatible with the configuration
7438 decisions below. Failure to do this may result in lost
7439 mail, broken <tt>From:</tt> lines, and other serious brain
7444 The mail spool is <file>/var/mail</file> and the interface to
7445 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7446 the FHS). On older systems, the mail spool may be
7447 physically located in <file>/var/spool/mail</file>, but all
7448 access to the mail spool should be via the
7449 <file>/var/mail</file> symlink. The mail spool is part of the
7450 base system and not part of the MTA package.
7454 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7455 programs (such as IMAP daemons) must lock the mailbox in an
7456 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7457 be combined with dot locking. To avoid deadlocks, a program
7458 should use <tt>fcntl()</tt> first and dot locking after
7459 this, or alternatively implement the two locking methods in
7460 a non blocking way<footnote>
7461 If it is not possible to establish both locks, the
7462 system shouldn't wait for the second lock to be
7463 established, but remove the first lock, wait a (random)
7464 time, and start over locking again.
7465 </footnote>. Using the functions <tt>maillock</tt> and
7466 <tt>mailunlock</tt> provided by the
7467 <tt>liblockfile*</tt><footnote>
7468 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7469 to use these functions.
7470 </footnote> packages is the recommended way to realize this.
7474 Mailboxes are generally mode 660
7475 <tt><var>user</var>.mail</tt> unless the system
7476 administrator has chosen otherwise. A MUA may remove a
7477 mailbox (unless it has nonstandard permissions) in which
7478 case the MTA or another MUA must recreate it if needed.
7479 Mailboxes must be writable by group mail.
7483 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7484 be setgid mail to do the locking mentioned above (and
7485 must obviously avoid accessing other users' mailboxes
7486 using this privilege).</p>
7489 <file>/etc/aliases</file> is the source file for the system mail
7490 aliases (e.g., postmaster, usenet, etc.), it is the one
7491 which the sysadmin and <prgn>postinst</prgn> scripts may
7492 edit. After <file>/etc/aliases</file> is edited the program or
7493 human editing it must call <prgn>newaliases</prgn>. All MTA
7494 packages must come with a <prgn>newaliases</prgn> program,
7495 even if it does nothing, but older MTA packages did not do
7496 this so programs should not fail if <prgn>newaliases</prgn>
7497 cannot be found. Note that because of this, all MTA
7498 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7499 <tt>Replaces: mail-transport-agent</tt> control file
7504 The convention of writing <tt>forward to
7505 <var>address</var></tt> in the mailbox itself is not
7506 supported. Use a <tt>.forward</tt> file instead.</p>
7509 The <prgn>rmail</prgn> program used by UUCP
7510 for incoming mail should be <file>/usr/sbin/rmail</file>.
7511 Likewise, <prgn>rsmtp</prgn>, for receiving
7512 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7516 If your package needs to know what hostname to use on (for
7517 example) outgoing news and mail messages which are generated
7518 locally, you should use the file <file>/etc/mailname</file>. It
7519 will contain the portion after the username and <tt>@</tt>
7520 (at) sign for email addresses of users on the machine
7521 (followed by a newline).
7525 Such package should check for the existence of this file
7526 when it is being configured. If it exists, it should be
7527 used without comment, although an MTA's configuration script
7528 may wish to prompt the user even if it finds that this file
7529 exists. If the file does not exist, the package should
7530 prompt the user for the value (preferably using
7531 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7532 as well as using it in the package's configuration. The
7533 prompt should make it clear that the name will not just be
7534 used by that package. For example, in this situation the
7535 <tt>inn</tt> package could say something like:
7536 <example compact="compact">
7537 Please enter the "mail name" of your system. This is the
7538 hostname portion of the address to be shown on outgoing
7539 news and mail messages. The default is
7540 <var>syshostname</var>, your system's host name. Mail
7541 name ["<var>syshostname</var>"]:
7543 where <var>syshostname</var> is the output of <tt>hostname
7549 <heading>News system configuration</heading>
7552 All the configuration files related to the NNTP (news)
7553 servers and clients should be located under
7554 <file>/etc/news</file>.</p>
7557 There are some configuration issues that apply to a number
7558 of news clients and server packages on the machine. These
7562 <tag><file>/etc/news/organization</file></tag>
7564 A string which should appear as the
7565 organization header for all messages posted
7566 by NNTP clients on the machine
7569 <tag><file>/etc/news/server</file></tag>
7571 Contains the FQDN of the upstream NNTP
7572 server, or localhost if the local machine is
7577 Other global files may be added as required for cross-package news
7584 <heading>Programs for the X Window System</heading>
7587 <heading>Providing X support and package priorities</heading>
7590 Programs that can be configured with support for the X
7591 Window System must be configured to do so and must declare
7592 any package dependencies necessary to satisfy their
7593 runtime requirements when using the X Window System. If
7594 such a package is of higher priority than the X packages
7595 on which it depends, it is required that either the
7596 X-specific components be split into a separate package, or
7597 that an alternative version of the package, which includes
7598 X support, be provided, or that the package's priority be
7604 <heading>Packages providing an X server</heading>
7607 Packages that provide an X server that, directly or
7608 indirectly, communicates with real input and display
7609 hardware should declare in their control data that they
7610 provide the virtual package <tt>xserver</tt>.<footnote>
7611 This implements current practice, and provides an
7612 actual policy for usage of the <tt>xserver</tt>
7613 virtual package which appears in the virtual packages
7614 list. In a nutshell, X servers that interface
7615 directly with the display and input hardware or via
7616 another subsystem (e.g., GGI) should provide
7617 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7618 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7624 <heading>Packages providing a terminal emulator</heading>
7627 Packages that provide a terminal emulator for the X Window
7628 System which meet the criteria listed below should declare
7629 in their control data that they provide the virtual
7630 package <tt>x-terminal-emulator</tt>. They should also
7631 register themselves as an alternative for
7632 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7637 To be an <tt>x-terminal-emulator</tt>, a program must:
7638 <list compact="compact">
7640 Be able to emulate a DEC VT100 terminal, or a
7641 compatible terminal.
7645 Support the command-line option <tt>-e
7646 <var>command</var></tt>, which creates a new
7647 terminal window<footnote>
7648 "New terminal window" does not necessarily mean
7649 a new top-level X window directly parented by
7650 the window manager; it could, if the terminal
7651 emulator application were so coded, be a new
7652 "view" in a multiple-document interface (MDI).
7654 and runs the specified <var>command</var>,
7655 interpreting the entirity of the rest of the command
7656 line as a command to pass straight to exec, in the
7657 manner that <tt>xterm</tt> does.
7661 Support the command-line option <tt>-T
7662 <var>title</var></tt>, which creates a new terminal
7663 window with the window title <var>title</var>.
7670 <heading>Packages providing a window manager</heading>
7673 Packages that provide a window manager should declare in
7674 their control data that they provide the virtual package
7675 <tt>x-window-manager</tt>. They should also register
7676 themselves as an alternative for
7677 <file>/usr/bin/x-window-manager</file>, with a priority
7678 calculated as follows:
7679 <list compact="compact">
7681 Start with a priority of 20.
7685 If the window manager supports the Debian menu
7686 system, add 20 points if this support is available
7687 in the package's default configuration (i.e., no
7688 configuration files belonging to the system or user
7689 have to be edited to activate the feature); if
7690 configuration files must be modified, add only 10
7696 If the window manager complies with <url
7697 id="http://www.freedesktop.org/standards/wm-spec.html"
7698 name="The Window Manager Specification Project">,
7699 written by the <url id="http://www.freedesktop.org/"
7700 name="Free Desktop Group">, add 40 points.
7704 If the window manager permits the X session to be
7705 restarted using a <em>different</em> window manager
7706 (without killing the X server) in its default
7707 configuration, add 10 points; otherwise add none.
7714 <heading>Packages providing fonts</heading>
7717 Packages that provide fonts for the X Window
7719 For the purposes of Debian Policy, a "font for the X
7720 Window System" is one which is accessed via X protocol
7721 requests. Fonts for the Linux console, for PostScript
7722 renderers, or any other purpose, do not fit this
7723 definition. Any tool which makes such fonts available
7724 to the X Window System, however, must abide by this
7727 must do a number of things to ensure that they are both
7728 available without modification of the X or font server
7729 configuration, and that they do not corrupt files used by
7730 other font packages to register information about
7734 Fonts of any type supported by the X Window System
7735 must be in a separate binary package from any
7736 executables, libraries, or documentation (except
7737 that specific to the fonts shipped, such as their
7738 license information). If one or more of the fonts
7739 so packaged are necessary for proper operation of
7740 the package with which they are associated the font
7741 package may be Recommended; if the fonts merely
7742 provide an enhancement, a Suggests relationship may
7743 be used. Packages must not Depend on font
7745 This is because the X server may retrieve fonts
7746 from the local filesystem or over the network
7747 from an X font server; the Debian package system
7748 is empowered to deal only with the local
7754 BDF fonts must be converted to PCF fonts with the
7755 <prgn>bdftopcf</prgn> utility (available in the
7756 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7757 placed in a directory that corresponds to their
7759 <list compact="compact">
7761 100 dpi fonts must be placed in
7762 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7766 75 dpi fonts must be placed in
7767 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7771 Character-cell fonts, cursor fonts, and other
7772 low-resolution fonts must be placed in
7773 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7779 Speedo fonts must be placed in
7780 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7784 Type 1 fonts must be placed in
7785 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7786 metric files are available, they must be placed here
7791 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7792 other than those listed above must be neither
7793 created nor used. (The <file>PEX</file>, <file>CID</file>,
7794 and <file>cyrillic</file> directories are excepted for
7795 historical reasons, but installation of files into
7796 these directories remains discouraged.)
7800 Font packages may, instead of placing files directly
7801 in the X font directories listed above, provide
7802 symbolic links in that font directory pointing to
7803 the files' actual location in the filesystem. Such
7804 a location must comply with the FHS.
7808 Font packages should not contain both 75dpi and
7809 100dpi versions of a font. If both are available,
7810 they should be provided in separate binary packages
7811 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7812 the names of the packages containing the
7813 corresponding fonts.
7817 Fonts destined for the <file>misc</file> subdirectory
7818 should not be included in the same package as 75dpi
7819 or 100dpi fonts; instead, they should be provided in
7820 a separate package with <tt>-misc</tt> appended to
7825 Font packages must not provide the files
7826 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7827 <file>fonts.scale</file> in a font directory:
7830 <file>fonts.dir</file> files must not be provided at all.
7834 <file>fonts.alias</file> and <file>fonts.scale</file>
7835 files, if needed, should be provided in the
7837 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7838 where <var>fontdir</var> is the name of the
7840 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7841 package's corresponding fonts are stored
7842 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7843 <var>package</var> is the name of the package
7844 that provides these fonts, and
7845 <var>extension</var> is either <tt>scale</tt>
7846 or <tt>alias</tt>, whichever corresponds to
7853 Font packages must declare a dependency on
7854 <tt>xutils (>> 4.0.3)</tt> in their control
7859 Font packages that provide one or more
7860 <file>fonts.scale</file> files as described above must
7861 invoke <prgn>update-fonts-scale</prgn> on each
7862 directory into which they installed fonts
7863 <em>before</em> invoking
7864 <prgn>update-fonts-dir</prgn> on that directory.
7865 This invocation must occur in both the
7866 <prgn>postinst</prgn> (for all arguments) and
7867 <prgn>postrm</prgn> (for all arguments except
7868 <tt>upgrade</tt>) scripts.
7872 Font packages that provide one or more
7873 <file>fonts.alias</file> files as described above must
7874 invoke <prgn>update-fonts-alias</prgn> on each
7875 directory into which they installed fonts. This
7876 invocation must occur in both the
7877 <prgn>postinst</prgn> (for all arguments) and
7878 <prgn>postrm</prgn> (for all arguments except
7879 <tt>upgrade</tt>) scripts.
7883 Font packages must invoke
7884 <prgn>update-fonts-dir</prgn> on each directory into
7885 which they installed fonts. This invocation must
7886 occur in both the <prgn>postinst</prgn> (for all
7887 arguments) and <prgn>postrm</prgn> (for all
7888 arguments except <tt>upgrade</tt>) scripts.
7892 Font packages must not provide alias names for the
7893 fonts they include which collide with alias names
7894 already in use by fonts already packaged.
7898 Font packages must not provide fonts with the same
7899 XLFD registry name as another font already packaged.
7906 <heading>Application defaults files</heading>
7909 Application defaults files must be installed in the
7910 directory <file>/etc/X11/app-defaults/</file> (use of a
7911 localized subdirectory of <file>/etc/X11/</file> as described
7912 in the <em>X Toolkit Intrinsics - C Language
7913 Interface</em> manual is also permitted). They must be
7914 registered as <tt>conffile</tt>s or handled as
7915 configuration files. Packages must not provide the
7916 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7920 Customization of programs' X resources may also be
7921 supported with the provision of a file with the same name
7922 as that of the package placed in the
7923 <file>/etc/X11/Xresources/</file> directory, which must
7924 registered as a <tt>conffile</tt> or handled as a
7925 configuration file.<footnote>
7926 Note that this mechanism is not the same as using
7927 app-defaults; app-defaults are tied to the client
7928 binary on the local filesystem, whereas X resources
7929 are stored in the X server and affect all connecting
7932 <em>Important:</em> packages that install files into the
7933 <file>/etc/X11/Xresources/</file> directory must conflict with
7934 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7935 it is possible for the installing package to destroy a
7936 previously-existing <file>/etc/X11/Xresources</file> file
7937 which had been customized by the system administrator.
7942 <heading>Installation directory issues</heading>
7945 Packages using the X Window System should not be
7946 configured to install files under the <file>/usr/X11R6/</file>
7947 directory unless they use <prgn>imake</prgn>. The
7948 <file>/usr/X11R6/</file> directory hierarchy should be
7949 regarded as deprecated for all packages except the X
7950 Window System itself, and those which use the
7951 <prgn>imake</prgn> program it provides, in which case the
7952 packages may transition out of the <file>/usr/X11R6/</file>
7953 directory at the maintainer's discretion.<footnote>
7954 <prgn>Imake</prgn>-using programs are exempt because,
7955 as long as they are written correctly, the pathnames
7956 they use to locate resources and install themselves
7957 are derived wholly from the X Window System
7958 configuration. Thus, in the event that the X Window
7959 System moves to <file>/usr/X11R7/</file>,
7960 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7961 that is required for these programs is a recompile
7962 against the corresponding X Window System library
7963 development packages.
7968 Programs that use GNU <prgn>autoconf</prgn> and
7969 <prgn>automake</prgn> are usually easily configured at
7970 compile time to use <file>/usr/</file> instead of
7971 <file>/usr/X11R6/</file>, and this should be done whenever
7972 possible. Configuration files for window managers and
7973 display managers should be placed in a subdirectory of
7974 <file>/etc/X11/</file> corresponding to the package name due
7975 to these programs' tight integration with the mechanisms
7976 of the X Window System. Application-level programs should
7977 use the <file>/etc/</file> directory unless otherwise mandated
7982 The installation of files into subdirectories
7983 of <file>/usr/X11R6/include/X11/</file> and
7984 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7985 package maintainers should determine if subdirectories of
7986 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7987 instead. (The use of symbolic links from the
7988 <file>X11R6</file> directories to other FHS-compliant
7989 locations is encouraged if the program is not easily
7990 configured to look elsewhere for its files.)
7994 Packages must not provide or install files into the directories
7995 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7996 <file>/usr/lib/X11/</file>. Files within a package should,
7997 however, make reference to these directories, rather than
7998 their <tt>X11R6</tt>-named counterparts
7999 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8000 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8001 referred to have not been moved to other FHS-compliant
8007 <heading>The OSF/Motif and OpenMotif libraries</heading>
8010 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8011 OpenMotif libraries</em><footnote>
8012 OSF/Motif and OpenMotif are collectively referred to as
8013 "Motif" in this policy document.
8015 should be compiled against and tested with LessTif (a free
8016 re-implementation of Motif) instead. If the maintainer
8017 judges that the program or programs do not work
8018 sufficiently well with LessTif to be distributed and
8019 supported, but do so when compiled against Motif, then two
8020 versions of the package should be created; one linked
8021 statically against Motif and with <tt>-smotif</tt>
8022 appended to the package name, and one linked dynamically
8023 against Motif and with <tt>-dmotif</tt> appended to the
8028 Both Motif-linked versions are dependent
8029 upon non-DFSG-compliant software and thus cannot be
8030 uploaded to the <em>main</em> distribution; if the
8031 software is itself DFSG-compliant it may be uploaded to
8032 the <em>contrib</em> distribution. While known existing
8033 versions of Motif permit unlimited redistribution of
8034 binaries linked against the library (whether statically or
8035 dynamically), it is the package maintainer's
8036 responsibility to determine whether this is permitted by
8037 the license of the copy of Motif in his or her possession.
8043 <heading>Perl programs and modules</heading>
8046 Perl programs and modules should follow the current Perl policy.
8050 The Perl policy can be found in the <tt>perl-policy</tt>
8051 files in the <tt>debian-policy</tt> package.
8052 It is also available from the Debian web mirrors at
8053 <tt><url name="/doc/packaging-manuals/perl-policy/"
8054 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
8055 and from the Debian archive mirrors at
8056 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
8057 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
8062 <heading>Emacs lisp programs</heading>
8065 Please refer to the "Debian Emacs Policy" for details of how to
8066 package emacs lisp programs.
8070 The Emacs policy is available in
8071 <file>debian-emacs-policy.gz</file> of the
8072 <package>emacsen-common</package> package.
8073 It is also available from the Debian web mirrors at
8074 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8075 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8080 <heading>Games</heading>
8083 The permissions on <file>/var/games</file> are mode 755, owner
8084 <tt>root</tt> and group <tt>root</tt>.
8088 Each game decides on its own security policy.</p>
8091 Games which require protected, privileged access to
8092 high-score files, savegames, etc., may be made
8093 set-<em>group</em>-id (mode 2755) and owned by
8094 <tt>root.games</tt>, and use files and directories with
8095 appropriate permissions (770 <tt>root.games</tt>, for
8096 example). They must not be made
8097 set-<em>user</em>-id, as this causes security problems. (If
8098 an attacker can subvert any set-user-id game they can
8099 overwrite the executable of any other, causing other players
8100 of these games to run a Trojan horse program. With a
8101 set-group-id game the attacker only gets access to less
8102 important game data, and if they can get at the other
8103 players' accounts at all it will take considerably more
8107 Some packages, for example some fortune cookie programs, are
8108 configured by the upstream authors to install with their
8109 data files or other static information made unreadable so
8110 that they can only be accessed through set-id programs
8111 provided. You should not do this in a Debian package: anyone can
8112 download the <file>.deb</file> file and read the data from it,
8113 so there is no point making the files unreadable. Not
8114 making the files unreadable also means that you don't have
8115 to make so many programs set-id, which reduces the risk of a
8119 As described in the FHS, binaries of games should be
8120 installed in the directory <file>/usr/games</file>. This also
8121 applies to games that use the X Window System. Manual pages
8122 for games (X and non-X games) should be installed in
8123 <file>/usr/share/man/man6</file>.</p>
8129 <heading>Documentation</heading>
8132 <heading>Manual pages</heading>
8135 You should install manual pages in <prgn>nroff</prgn> source
8136 form, in appropriate places under <file>/usr/share/man</file>.
8137 You should only use sections 1 to 9 (see the FHS for more
8138 details). You must not install a preformatted "cat page".
8142 Each program, utility, and function should have an
8143 associated manual page included in the same package. It is
8144 suggested that all configuration files also have a manual
8145 page included as well. Manual pages for protocols and other
8146 auxiliary things are optional.
8150 If no manual page is available, this is considered as a bug
8151 and should be reported to the Debian Bug Tracking System (the
8152 maintainer of the package is allowed to write this bug report
8153 themselves, if they so desire). Do not close the bug report
8154 until a proper manpage is available.<footnote>
8155 It is not very hard to write a man page. See the
8156 <url id="http://www.schweikhardt.net/man_page_howto.html"
8157 name="Man-Page-HOWTO">,
8158 <manref name="man" section="7">, the examples
8159 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8160 the helper programs <prgn>help2man</prgn>, or the
8161 directory <file>/usr/share/doc/man-db/examples</file>.
8166 You may forward a complaint about a missing manpage to the
8167 upstream authors, and mark the bug as forwarded in the
8168 Debian bug tracking system. Even though the GNU Project do
8169 not in general consider the lack of a manpage to be a bug,
8170 we do; if they tell you that they don't consider it a bug
8171 you should leave the bug in our bug tracking system open
8176 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8180 If one manpage needs to be accessible via several names it
8181 is better to use a symbolic link than the <file>.so</file>
8182 feature, but there is no need to fiddle with the relevant
8183 parts of the upstream source to change from <file>.so</file> to
8184 symlinks: don't do it unless it's easy. You should not
8185 create hard links in the manual page directories, nor put
8186 absolute filenames in <file>.so</file> directives. The filename
8187 in a <file>.so</file> in a manpage should be relative to the
8188 base of the manpage tree (usually
8189 <file>/usr/share/man</file>). If you do not create any links
8190 (whether symlinks, hard links, or <tt>.so</tt> directives)
8191 in the filesystem to the alternate names of the manpage,
8192 then you should not rely on <prgn>man</prgn> finding your
8193 manpage under those names based solely on the information in
8194 the manpage's header.<footnote>
8195 Supporting this in <prgn>man</prgn> often requires
8196 unreasonable processing time to find a manual page or to
8197 report that none exists, and moves knowledge into man's
8198 database that would be better left in the filesystem.
8199 This support is therefore deprecated and will cease to
8200 be present in the future.
8206 <heading>Info documents</heading>
8209 Info documents should be installed in <file>/usr/share/info</file>.
8210 They should be compressed with <tt>gzip -9</tt>.
8214 Your package should call <prgn>install-info</prgn> to update
8215 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8216 script when called with a <tt>configure</tt> argument, for
8218 <example compact="compact">
8219 install-info --quiet --section Development Development \
8220 /usr/share/info/foobar.info
8224 It is a good idea to specify a section for the location of
8225 your program; this is done with the <tt>--section</tt>
8226 switch. To determine which section to use, you should look
8227 at <file>/usr/share/info/dir</file> on your system and choose the most
8228 relevant (or create a new section if none of the current
8229 sections are relevant). Note that the <tt>--section</tt>
8230 flag takes two arguments; the first is a regular expression
8231 to match (case-insensitively) against an existing section,
8232 the second is used when creating a new one.</p>
8235 You should remove the entries in the <prgn>prerm</prgn>
8236 script when called with a <tt>remove</tt> argument:
8237 <example compact="compact">
8238 install-info --quiet --remove /usr/share/info/foobar.info
8242 If <prgn>install-info</prgn> cannot find a description entry
8243 in the Info file you must supply one. See <manref
8244 name="install-info" section="8"> for details.</p>
8248 <heading>Additional documentation</heading>
8251 Any additional documentation that comes with the package may
8252 be installed at the discretion of the package maintainer.
8253 Text documentation should be installed in the directory
8254 <file>/usr/share/doc/<var>package</var></file>, where
8255 <var>package</var> is the name of the package, and
8256 compressed with <tt>gzip -9</tt> unless it is small.
8260 If a package comes with large amounts of documentation which
8261 many users of the package will not require you should create
8262 a separate binary package to contain it, so that it does not
8263 take up disk space on the machines of users who do not need
8264 or want it installed.</p>
8267 It is often a good idea to put text information files
8268 (<file>README</file>s, changelogs, and so forth) that come with
8269 the source package in <file>/usr/share/doc/<var>package</var></file>
8270 in the binary package. However, you don't need to install
8271 the instructions for building and installing the package, of
8275 Packages must not require the existence of any files in
8276 <file>/usr/share/doc/</file> in order to function
8278 The system administrator should be able to
8279 delete files in <file>/usr/share/doc/</file> without causing
8280 any programs to break.
8282 Any files that are referenced by programs but are also
8283 useful as standalone documentation should be installed under
8284 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8285 <file>/usr/share/doc/<var>package</var></file>.
8289 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8290 link to another directory in <file>/usr/share/doc</file> only if
8291 the two packages both come from the same source and the
8292 first package Depends on the second.
8296 Former Debian releases placed all additional documentation
8297 in <file>/usr/doc/<var>package</var></file>. This has been
8298 changed to <file>/usr/share/doc/<var>package</var></file>,
8299 and packages must not put documentation in the directory
8300 <file>/usr/doc/<var>package</var></file>. <footnote>
8301 At this phase of the transition, we no longer require a
8302 symbolic link in <file>/usr/doc/</file>. At a later point,
8303 policy shall change to make the symbolic links a bug.
8309 <heading>Preferred documentation formats</heading>
8312 The unification of Debian documentation is being carried out
8316 If your package comes with extensive documentation in a
8317 markup format that can be converted to various other formats
8318 you should if possible ship HTML versions in a binary
8319 package, in the directory
8320 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8321 its subdirectories.<footnote>
8322 The rationale: The important thing here is that HTML
8323 docs should be available in <em>some</em> package, not
8324 necessarily in the main binary package.
8329 Other formats such as PostScript may be provided at the
8330 package maintainer's discretion.
8334 <sect id="copyrightfile">
8335 <heading>Copyright information</heading>
8338 Every package must be accompanied by a verbatim copy of its
8339 copyright and distribution license in the file
8340 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8341 file must neither be compressed nor be a symbolic link.
8345 In addition, the copyright file must say where the upstream
8346 sources (if any) were obtained. It should name the original
8347 authors of the package and the Debian maintainer(s) who were
8348 involved with its creation.</p>
8351 A copy of the file which will be installed in
8352 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8353 be in <file>debian/copyright</file> in the source package.
8357 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8358 link to another directory in <file>/usr/share/doc</file> only if
8359 the two packages both come from the same source and the
8360 first package Depends on the second. These rules are
8361 important because copyrights must be extractable by
8366 Packages distributed under the UCB BSD license, the Artistic
8367 license, the GNU GPL, and the GNU LGPL should refer to the
8368 files <file>/usr/share/common-licenses/BSD</file>,
8369 <file>/usr/share/common-licenses/Artistic</file>,
8370 <file>/usr/share/common-licenses/GPL</file>, and
8371 <file>/usr/share/common-licenses/LGPL</file> respectively,
8372 rather than quoting them in the copyright file.
8376 You should not use the copyright file as a general <file>README</file>
8377 file. If your package has such a file it should be
8378 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8379 <file>README.Debian</file> or some other appropriate place.</p>
8383 <heading>Examples</heading>
8386 Any examples (configurations, source files, whatever),
8387 should be installed in a directory
8388 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8389 files should not be referenced by any program: they're there
8390 for the benefit of the system administrator and users as
8391 documentation only. Architecture-specific example files
8392 should be installed in a directory
8393 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8395 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8396 latter directory itself may be a symbolic link to the
8401 If the purpose of a package is to provide examples, then the
8402 example files may be installed into
8403 <file>/usr/share/doc/<var>package</var></file>.
8407 <sect id="changelogs">
8408 <heading>Changelog files</heading>
8411 Packages that are not Debian-native must contain a
8412 compressed copy of the <file>debian/changelog</file> file from
8413 the Debian source tree in
8414 <file>/usr/share/doc/<var>package</var></file> with the name
8415 <file>changelog.Debian.gz</file>.
8419 If an upstream changelog is available, it should be accessible as
8420 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8421 plain text. If the upstream changelog is distributed in
8422 HTML, it should be made available in that form as
8423 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8424 and a plain text <file>changelog.gz</file> should be generated
8425 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8426 the upstream changelog files do not already conform to this
8427 naming convention, then this may be achieved either by
8428 renaming the files, or by adding a symbolic link, at the
8429 maintainer's discretion.<footnote>
8430 Rationale: People should not have to look in places for
8431 upstream changelogs merely because they are given
8432 different names or are distributed in HTML format.
8437 All of these files should be installed compressed using
8438 <tt>gzip -9</tt>, as they will become large with time even
8439 if they start out small.
8443 If the package has only one changelog which is used both as
8444 the Debian changelog and the upstream one because there is
8445 no separate upstream maintainer then that changelog should
8446 usually be installed as
8447 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8448 there is a separate upstream maintainer, but no upstream
8449 changelog, then the Debian changelog should still be called
8450 <file>changelog.Debian.gz</file>.
8454 For details about the format and contents of the Debian
8455 changelog file, please see <ref id="dpkgchangelog">.
8460 <appendix id="pkg-scope">
8461 <heading>Introduction and scope of these appendices</heading>
8464 These appendices are taken essentially verbatim from the
8465 now-deprecated Packaging Manual, version 3.2.1.0. They are
8466 the chapters which are likely to be of use to package
8467 maintainers and which have not already been included in the
8468 policy document itself. Most of these sections are very likely
8469 not relevant to policy; they should be treated as
8470 documentation for the packaging system. Please note that these
8471 appendices are included for convenience, and for historical
8472 reasons: they used to be part of policy package, and they have
8473 not yet been incorporated into dpkg documentation. However,
8474 they still have value, and hence they are presented here.
8478 They have not yet been checked to ensure that they are
8479 compatible with the contents of policy, and if there are any
8480 contradictions, the version in the main policy document takes
8481 precedence. The remaining chapters of the old Packaging
8482 Manual have also not been read in detail to ensure that there
8483 are not parts which have been left out. Both of these will be
8488 Certain parts of the Packaging manual were integrated into the
8489 Policy Manual proper, and removed from the appendices. Links
8490 have been placed from the old locations to the new ones.
8494 <prgn>dpkg</prgn> is a suite of programs for creating binary
8495 package files and installing and removing them on Unix
8497 <prgn>dpkg</prgn> is targetted primarily at Debian
8498 GNU/Linux, but may work on or be ported to other
8504 The binary packages are designed for the management of
8505 installed executable programs (usually compiled binaries) and
8506 their associated data, though source code examples and
8507 documentation are provided as part of some packages.</p>
8510 This manual describes the technical aspects of creating Debian
8511 binary packages (<file>.deb</file> files). It documents the
8512 behaviour of the package management programs
8513 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8514 they interact with packages.</p>
8517 It also documents the interaction between
8518 <prgn>dselect</prgn>'s core and the access method scripts it
8519 uses to actually install the selected packages, and describes
8520 how to create a new access method.</p>
8523 This manual does not go into detail about the options and
8524 usage of the package building and installation tools. It
8525 should therefore be read in conjuction with those programs'
8530 The utility programs which are provided with <prgn>dpkg</prgn>
8531 for managing various system configuration and similar issues,
8532 such as <prgn>update-rc.d</prgn> and
8533 <prgn>install-info</prgn>, are not described in detail here -
8534 please see their manpages.
8538 It is assumed that the reader is reasonably familiar with the
8539 <prgn>dpkg</prgn> System Administrators' manual.
8540 Unfortunately this manual does not yet exist.
8544 The Debian version of the FSF's GNU hello program is provided
8545 as an example for people wishing to create Debian
8546 packages. The Debian <prgn>debmake</prgn> package is
8547 recommended as a very helpful tool in creating and maintaining
8548 Debian packages. However, while the tools and examples are
8549 helpful, they do not replace the need to read and follow the
8550 Policy and Programmer's Manual.</p>
8553 <appendix id="pkg-binarypkg">
8554 <heading>Binary packages (from old Packaging Manual)</heading>
8557 The binary package has two main sections. The first part
8558 consists of various control information files and scripts used
8559 by <prgn>dpkg</prgn> when installing and removing. See <ref
8560 id="pkg-controlarea">.
8564 The second part is an archive containing the files and
8565 directories to be installed.
8569 In the future binary packages may also contain other
8570 components, such as checksums and digital signatures. The
8571 format for the archive is described in full in the
8572 <file>deb(5)</file> manpage.
8576 <sect id="pkg-bincreating"><heading>Creating package files -
8577 <prgn>dpkg-deb</prgn>
8581 All manipulation of binary package files is done by
8582 <prgn>dpkg-deb</prgn>; it's the only program that has
8583 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8584 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8585 will spot that the options requested are appropriate to
8586 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8591 In order to create a binary package you must make a
8592 directory tree which contains all the files and directories
8593 you want to have in the filesystem data part of the package.
8594 In Debian-format source packages this directory is usually
8595 <file>debian/tmp</file>, relative to the top of the package's
8600 They should have the locations (relative to the root of the
8601 directory tree you're constructing) ownerships and
8602 permissions which you want them to have on the system when
8607 With current versions of <prgn>dpkg</prgn> the uid/username
8608 and gid/groupname mappings for the users and groups being
8609 used should be the same on the system where the package is
8610 built and the one where it is installed.
8614 You need to add one special directory to the root of the
8615 miniature filesystem tree you're creating:
8616 <prgn>DEBIAN</prgn>. It should contain the control
8617 information files, notably the binary package control file
8618 (see <ref id="pkg-controlfile">).
8622 The <prgn>DEBIAN</prgn> directory will not appear in the
8623 filesystem archive of the package, and so won't be installed
8624 by <prgn>dpkg</prgn> when the package is installed.
8628 When you've prepared the package, you should invoke:
8630 dpkg --build <var>directory</var>
8635 This will build the package in
8636 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8637 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8638 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8643 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8644 to examine the contents of this newly-created file. You may find the
8645 output of following commands enlightening:
8647 dpkg-deb --info <var>filename</var>.deb
8648 dpkg-deb --contents <var>filename</var>.deb
8649 dpkg --contents <var>filename</var>.deb
8651 To view the copyright file for a package you could use this command:
8653 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8658 <sect id="pkg-controlarea">
8659 <heading>Package control information files</heading>
8662 The control information portion of a binary package is a
8663 collection of files with names known to <prgn>dpkg</prgn>.
8664 It will treat the contents of these files specially - some
8665 of them contain information used by <prgn>dpkg</prgn> when
8666 installing or removing the package; others are scripts which
8667 the package maintainer wants <prgn>dpkg</prgn> to run.
8671 It is possible to put other files in the package control
8672 area, but this is not generally a good idea (though they
8673 will largely be ignored).
8677 Here is a brief list of the control info files supported by
8678 <prgn>dpkg</prgn> and a summary of what they're used for.
8683 <tag><tt>control</tt>
8686 This is the key description file used by
8687 <prgn>dpkg</prgn>. It specifies the package's name
8688 and version, gives its description for the user,
8689 states its relationships with other packages, and so
8690 forth. See <ref id="sourcecontrolfiles"> and
8691 <ref id="binarycontrolfiles">.
8695 It is usually generated automatically from information
8696 in the source package by the
8697 <prgn>dpkg-gencontrol</prgn> program, and with
8698 assistance from <prgn>dpkg-shlibdeps</prgn>.
8699 See <ref id="pkg-sourcetools">.
8703 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8708 These are exectuable files (usually scripts) which
8709 <prgn>dpkg</prgn> runs during installation, upgrade
8710 and removal of packages. They allow the package to
8711 deal with matters which are particular to that package
8712 or require more complicated processing than that
8713 provided by <prgn>dpkg</prgn>. Details of when and
8714 how they are called are in <ref id="maintainerscripts">.
8718 It is very important to make these scripts idempotent.
8719 See <ref id="idempotency">.
8723 The maintainer scripts are guaranteed to run with a
8724 controlling terminal and can interact with the user.
8725 See <ref id="controllingterminal">.
8729 <tag><tt>conffiles</tt>
8732 This file contains a list of configuration files which
8733 are to be handled automatically by <prgn>dpkg</prgn>
8734 (see <ref id="pkg-conffiles">). Note that not necessarily
8735 every configuration file should be listed here.
8738 <tag><tt>shlibs</tt>
8741 This file contains a list of the shared libraries
8742 supplied by the package, with dependency details for
8743 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8744 when it determines what dependencies are required in a
8745 package control file. The <tt>shlibs</tt> file format
8746 is described on <ref id="shlibs">.
8751 <sect id="pkg-controlfile">
8752 <heading>The main control information file: <tt>control</tt></heading>
8755 The most important control information file used by
8756 <prgn>dpkg</prgn> when it installs a package is
8757 <tt>control</tt>. It contains all the package's "vital
8762 The binary package control files of packages built from
8763 Debian sources are made by a special tool,
8764 <prgn>dpkg-gencontrol</prgn>, which reads
8765 <file>debian/control</file> and <file>debian/changelog</file> to
8766 find the information it needs. See <ref id="pkg-sourcepkg"> for
8771 The fields in binary package control files are listed in
8772 <ref id="binarycontrolfiles">.
8776 A description of the syntax of control files and the purpose
8777 of the fields is available in <ref id="controlfields">.
8782 <heading>Time Stamps</heading>
8785 See <ref id="timestamps">.
8790 <appendix id="pkg-sourcepkg">
8791 <heading>Source packages (from old Packaging Manual) </heading>
8794 The Debian binary packages in the distribution are generated
8795 from Debian sources, which are in a special format to assist
8796 the easy and automatic building of binaries.
8799 <sect id="pkg-sourcetools">
8800 <heading>Tools for processing source packages</heading>
8803 Various tools are provided for manipulating source packages;
8804 they pack and unpack sources and help build of binary
8805 packages and help manage the distribution of new versions.
8809 They are introduced and typical uses described here; see
8810 <manref name="dpkg-source" section="1"> for full
8811 documentation about their arguments and operation.
8815 For examples of how to construct a Debian source package,
8816 and how to use those utilities that are used by Debian
8817 source packages, please see the <prgn>hello</prgn> example
8821 <sect1 id="pkg-dpkg-source">
8823 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8828 This program is frequently used by hand, and is also
8829 called from package-independent automated building scripts
8830 such as <prgn>dpkg-buildpackage</prgn>.
8834 To unpack a package it is typically invoked with
8836 dpkg-source -x <var>.../path/to/filename</var>.dsc
8841 with the <file><var>filename</var>.tar.gz</file> and
8842 <file><var>filename</var>.diff.gz</file> (if applicable) in
8843 the same directory. It unpacks into
8844 <file><var>package</var>-<var>version</var></file>, and if
8846 <file><var>package</var>-<var>version</var>.orig</file>, in
8847 the current directory.
8851 To create a packed source archive it is typically invoked:
8853 dpkg-source -b <var>package</var>-<var>version</var>
8858 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8859 <file>.diff.gz</file> (if appropriate) in the current
8860 directory. <prgn>dpkg-source</prgn> does not clean the
8861 source tree first - this must be done separately if it is
8866 See also <ref id="pkg-sourcearchives">.</p>
8870 <sect1 id="pkg-dpkg-buildpackage">
8872 <prgn>dpkg-buildpackage</prgn> - overall package-building
8877 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8878 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8879 targets <tt>clean</tt>, <tt>build</tt> and
8880 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8881 <prgn>pgp</prgn> to build a signed source and binary
8886 It is usually invoked by hand from the top level of the
8887 built or unbuilt source directory. It may be invoked with
8888 no arguments; useful arguments include:
8889 <taglist compact="compact">
8890 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8893 Do not PGP-sign the <tt>.changes</tt> file or the
8894 source package <tt>.dsc</tt> file, respectively.</p>
8896 <tag><tt>-p<var>pgp-command</var></tt></tag>
8899 Invoke <var>pgp-command</var> instead of finding
8900 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8901 <var>pgp-command</var> must behave just like
8902 <prgn>pgp</prgn>.</p>
8904 <tag><tt>-r<var>root-command</var></tt></tag>
8907 When root privilege is required, invoke the command
8908 <var>root-command</var>. <var>root-command</var>
8909 should invoke its first argument as a command, from
8910 the <prgn>PATH</prgn> if necessary, and pass its
8911 second and subsequent arguments to the command it
8912 calls. If no <var>root-command</var> is supplied
8913 then <var>dpkg-buildpackage</var> will take no
8914 special action to gain root privilege, so that for
8915 most packages it will have to be invoked as root to
8918 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8921 Two types of binary-only build and upload - see
8922 <manref name="dpkg-source" section="1">.
8929 <sect1 id="pkg-dpkg-gencontrol">
8931 <prgn>dpkg-gencontrol</prgn> - generates binary package
8936 This program is usually called from <file>debian/rules</file>
8937 (see <ref id="pkg-sourcetree">) in the top level of the source
8942 This is usually done just before the files and directories in the
8943 temporary directory tree where the package is being built have their
8944 permissions and ownerships set and the package is constructed using
8945 <prgn>dpkg-deb/</prgn>
8947 This is so that the control file which is produced has
8948 the right permissions
8953 <prgn>dpkg-gencontrol</prgn> must be called after all the
8954 files which are to go into the package have been placed in
8955 the temporary build directory, so that its calculation of
8956 the installed size of a package is correct.
8960 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8961 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8962 variable substitutions created by
8963 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8968 For a package which generates only one binary package, and
8969 which builds it in <file>debian/tmp</file> relative to the top
8970 of the source package, it is usually sufficient to call
8971 <prgn>dpkg-gencontrol</prgn>.
8975 Sources which build several binaries will typically need
8978 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8979 </example> The <tt>-P</tt> tells
8980 <prgn>dpkg-gencontrol</prgn> that the package is being
8981 built in a non-default directory, and the <tt>-p</tt>
8982 tells it which package's control file should be generated.
8986 <prgn>dpkg-gencontrol</prgn> also adds information to the
8987 list of files in <file>debian/files</file>, for the benefit of
8988 (for example) a future invocation of
8989 <prgn>dpkg-genchanges</prgn>.</p>
8992 <sect1 id="pkg-dpkg-shlibdeps">
8994 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8999 This program is usually called from <file>debian/rules</file>
9000 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9001 id="pkg-sourcetree">), in the top level of the source tree.
9005 Its arguments are executables.
9008 In a forthcoming dpkg version,
9009 <prgn>dpkg-shlibdeps</prgn> would be required to be
9010 called on shared libraries as well.
9013 They may be specified either in the locations in the
9014 source tree where they are created or in the locations
9015 in the temporary build tree where they are installed
9016 prior to binary package creation.
9018 </footnote> for which shared library dependencies should
9019 be included in the binary package's control file.
9023 If some of the found shared libraries should only
9024 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9025 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9026 by using the <tt>-d<var>dependency-field</var></tt> option
9027 before those executable(s). (Each <tt>-d</tt> option
9028 takes effect until the next <tt>-d</tt>.)
9032 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9033 output control file to be modified. Instead by default it
9034 adds to the <file>debian/substvars</file> file variable
9035 settings like <tt>shlibs:Depends</tt>. These variable
9036 settings must be referenced in dependency fields in the
9037 appropriate per-binary-package sections of the source
9042 For example, a package that generates an essential part
9043 which requires dependencies, and optional parts that
9044 which only require a recommendation, would separate those
9045 two sets of dependencies into two different fields.<footnote>
9046 At the time of writing, an example for this was the
9047 <package/xmms/ package, with Depends used for the xmms
9048 executable, Recommends for the plug-ins and Suggests for
9049 even more optional features provided by unzip.
9051 It can say in its <file>debian/rules</file>:
9053 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9054 -dRecommends <var>optionalpart anotheroptionalpart</var>
9056 and then in its main control file <file>debian/control</file>:
9059 Depends: ${shlibs:Pre-Depends}
9060 Recommends: ${shlibs:Recommends}
9066 Sources which produce several binary packages with
9067 different shared library dependency requirements can use
9068 the <tt>-p<var>varnameprefix</var></tt> option to override
9069 the default <tt>shlibs:</tt> prefix (one invocation of
9070 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9071 They can thus produce several sets of dependency
9072 variables, each of the form
9073 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9074 which can be referred to in the appropriate parts of the
9075 binary package control files.
9080 <sect1 id="pkg-dpkg-distaddfile">
9082 <prgn>dpkg-distaddfile</prgn> - adds a file to
9083 <file>debian/files</file>
9087 Some packages' uploads need to include files other than
9088 the source and binary package files.
9092 <prgn>dpkg-distaddfile</prgn> adds a file to the
9093 <file>debian/files</file> file so that it will be included in
9094 the <file>.changes</file> file when
9095 <prgn>dpkg-genchanges</prgn> is run.
9099 It is usually invoked from the <tt>binary</tt> target of
9100 <file>debian/rules</file>:
9102 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9104 The <var>filename</var> is relative to the directory where
9105 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9106 is usually the directory above the top level of the source
9107 tree. The <file>debian/rules</file> target should put the
9108 file there just before or just after calling
9109 <prgn>dpkg-distaddfile</prgn>.
9113 The <var>section</var> and <var>priority</var> are passed
9114 unchanged into the resulting <file>.changes</file> file.
9119 <sect1 id="pkg-dpkg-genchanges">
9121 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9126 This program is usually called by package-independent
9127 automatic building scripts such as
9128 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9133 It is usually called in the top level of a built source
9134 tree, and when invoked with no arguments will print out a
9135 straightforward <file>.changes</file> file based on the
9136 information in the source package's changelog and control
9137 file and the binary and source packages which should have
9143 <sect1 id="pkg-dpkg-parsechangelog">
9145 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9146 representation of a changelog
9150 This program is used internally by
9151 <prgn>dpkg-source</prgn> et al. It may also occasionally
9152 be useful in <file>debian/rules</file> and elsewhere. It
9153 parses a changelog, <file>debian/changelog</file> by default,
9154 and prints a control-file format representation of the
9155 information in it to standard output.
9159 <sect1 id="pkg-dpkg-architecture">
9161 <prgn>dpkg-architecture</prgn> - information about the build and
9166 This program can be used manually, but is also invoked by
9167 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9168 to set environment or make variables which specify the build and
9169 host architecture for the package building process.
9174 <sect id="pkg-sourcetree">
9175 <heading>The Debianised source tree</heading>
9178 The source archive scheme described later is intended to
9179 allow a Debianised source tree with some associated control
9180 information to be reproduced and transported easily. The
9181 Debianised source tree is a version of the original program
9182 with certain files added for the benefit of the
9183 Debianisation process, and with any other changes required
9184 made to the rest of the source code and installation
9189 The extra files created for Debian are in the subdirectory
9190 <file>debian</file> of the top level of the Debianised source
9191 tree. They are described below.
9194 <sect1 id="pkg-debianrules">
9195 <heading><file>debian/rules</file> - the main building script</heading>
9198 See <ref id="debianrules">.
9203 <sect1 id="pkg-dpkgchangelog">
9204 <heading><file>debian/changelog</file></heading>
9207 See <ref id="dpkgchangelog">.
9211 It is recommended that the entire changelog be encoded in the
9212 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9214 <url id="http://www.unicode.org/"
9215 name="Unicode">.<footnote>
9217 Support for Unicode, and specifically UTF-8, is
9218 steadily increasing among popular applications in
9219 Debian. For example, in unstable, GNOME 2 has
9220 excellent support (almost level 2) in almost all its
9221 applications; the big remaining one is gnome-terminal,
9222 of which one requires development versions in order to
9223 support UTF-8 (available in Debian experimental now if
9224 you want to play). I think that by the time sarge is
9225 released, UTF-8 support will start to hit critical
9228 I think it is fairly obvious that we need to
9229 eventually transition to UTF-8 for our package
9230 infrastructure; it is really the only sane charset in
9231 an international environment. Now, we can't switch to
9232 using UTF-8 for package control fields and the like
9233 until dpkg has better support, but one thing we can
9234 start doing today is requesting that Debian changelogs
9235 are UTF-8 encoded. At some point in time, we can start
9236 requiring them to do so.
9239 Checking for non-UTF8 characters in a changelog is
9240 trivial. Dump the file through
9241 <example>iconv -f utf-8 -t ucs-4</example>
9242 discard the output, and check the return
9243 value. If there are any characters in the stream
9244 which are invalid UTF-8 sequences, iconv will exit
9245 with an error code; and this will be the case for the
9246 vast majority of other character sets.
9251 <sect2><heading>Defining alternative changelog formats
9255 It is possible to use a different format to the standard
9256 one, by providing a parser for the format you wish to
9261 In order to have <tt>dpkg-parsechangelog</tt> run your
9262 parser, you must include a line within the last 40 lines
9263 of your file matching the Perl regular expression:
9264 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9265 parentheses should be the name of the format. For
9266 example, you might say:
9268 @@@ changelog-format: joebloggs @@@
9270 Changelog format names are non-empty strings of alphanumerics.
9274 If such a line exists then <tt>dpkg-parsechangelog</tt>
9275 will look for the parser as
9276 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9278 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9279 it is an error for it not to find it, or for it not to
9280 be an executable program. The default changelog format
9281 is <tt>dpkg</tt>, and a parser for it is provided with
9282 the <tt>dpkg</tt> package.
9286 The parser will be invoked with the changelog open on
9287 standard input at the start of the file. It should read
9288 the file (it may seek if it wishes) to determine the
9289 information required and return the parsed information
9290 to standard output in the form of a series of control
9291 fields in the standard format. By default it should
9292 return information about only the most recent version in
9293 the changelog; it should accept a
9294 <tt>-v<var>version</var></tt> option to return changes
9295 information from all versions present <em>strictly
9296 after</em> <var>version</var>, and it should then be an
9297 error for <var>version</var> not to be present in the
9303 <list compact="compact">
9304 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9305 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9306 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9307 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9308 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9309 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9310 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9315 If several versions are being returned (due to the use
9316 of <tt>-v</tt>), the urgency value should be of the
9317 highest urgency code listed at the start of any of the
9318 versions requested followed by the concatenated
9319 (space-separated) comments from all the versions
9320 requested; the maintainer, version, distribution and
9321 date should always be from the most recent version.
9325 For the format of the <tt>Changes</tt> field see
9326 <ref id="f-Changes">.
9330 If the changelog format which is being parsed always or
9331 almost always leaves a blank line between individual
9332 change notes these blank lines should be stripped out,
9333 so as to make the resulting output compact.
9337 If the changelog format does not contain date or package
9338 name information this information should be omitted from
9339 the output. The parser should not attempt to synthesise
9340 it or find it from other sources.
9344 If the changelog does not have the expected format the
9345 parser should exit with a nonzero exit status, rather
9346 than trying to muddle through and possibly generating
9351 A changelog parser may not interact with the user at
9357 <sect1 id="pkg-srcsubstvars">
9358 <heading><file>debian/substvars</file> and variable substitutions</heading>
9361 See <ref id="substvars">.
9367 <heading><file>debian/files</file></heading>
9370 See <ref id="debianfiles">.
9374 <sect1><heading><file>debian/tmp</file>
9378 This is the canonical temporary location for the
9379 construction of binary packages by the <tt>binary</tt>
9380 target. The directory <file>tmp</file> serves as the root of
9381 the filesystem tree as it is being constructed (for
9382 example, by using the package's upstream makefiles install
9383 targets and redirecting the output there), and it also
9384 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9385 id="pkg-bincreating">.
9389 If several binary packages are generated from the same
9390 source tree it is usual to use several
9391 <file>debian/tmp<var>something</var></file> directories, for
9392 example <file>tmp-a</file> or <file>tmp-doc</file>.
9396 Whatever <file>tmp</file> directories are created and used by
9397 <tt>binary</tt> must of course be removed by the
9398 <tt>clean</tt> target.</p></sect1>
9402 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9406 As it exists on the FTP site, a Debian source package
9407 consists of three related files. You must have the right
9408 versions of all three to be able to use them.
9413 <tag>Debian source control file - <tt>.dsc</tt></tag>
9415 This file is a control file used by <prgn>dpkg-source</prgn>
9416 to extract a source package.
9417 See <ref id="debiansourcecontrolfiles">.
9421 Original source archive -
9423 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9430 This is a compressed (with <tt>gzip -9</tt>)
9431 <prgn>tar</prgn> file containing the source code from
9432 the upstream authors of the program. The tarfile
9433 unpacks into a directory
9434 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9435 and does not contain files anywhere other than in
9436 there or in its subdirectories.</p>
9440 Debianisation diff -
9442 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9448 This is a unified context diff (<tt>diff -u</tt>)
9449 giving the changes which are required to turn the
9450 original source into the Debian source. These changes
9451 may only include editing and creating plain files.
9452 The permissions of files, the targets of symbolic
9453 links and the characteristics of special files or
9454 pipes may not be changed and no files may be removed
9459 All the directories in the diff must exist, except the
9460 <file>debian</file> subdirectory of the top of the source
9461 tree, which will be created by
9462 <prgn>dpkg-source</prgn> if necessary when unpacking.
9466 The <prgn>dpkg-source</prgn> program will
9467 automatically make the <file>debian/rules</file> file
9468 executable (see below).</p></item>
9473 If there is no original source code - for example, if the
9474 package is specially prepared for Debian or the Debian
9475 maintainer is the same as the upstream maintainer - the
9476 format is slightly different: then there is no diff, and the
9478 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9479 contains a directory
9480 <file><var>package</var>-<var>version</var></file>.
9485 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9488 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9489 Debian source package. However, if it is not available it
9490 is possible to unpack a Debian source archive as follows:
9491 <enumlist compact="compact">
9494 Untar the tarfile, which will create a <file>.orig</file>
9498 <p>Rename the <file>.orig</file> directory to
9499 <file><var>package</var>-<var>version</var></file>.</p>
9503 Create the subdirectory <file>debian</file> at the top of
9504 the source tree.</p>
9506 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9508 <item><p>Untar the tarfile again if you want a copy of the original
9509 source code alongside the Debianised version.</p>
9514 It is not possible to generate a valid Debian source archive
9515 without using <prgn>dpkg-source</prgn>. In particular,
9516 attempting to use <prgn>diff</prgn> directly to generate the
9517 <file>.diff.gz</file> file will not work.
9521 <heading>Restrictions on objects in source packages</heading>
9524 The source package may not contain any hard links
9526 This is not currently detected when building source
9527 packages, but only when extracting
9531 Hard links may be permitted at some point in the
9532 future, but would require a fair amount of
9534 </footnote>, device special files, sockets or setuid or
9537 Setgid directories are allowed.
9542 The source packaging tools manage the changes between the
9543 original and Debianised source using <prgn>diff</prgn> and
9544 <prgn>patch</prgn>. Turning the original source tree as
9545 included in the <file>.orig.tar.gz</file> into the debianised
9546 source must not involve any changes which cannot be
9547 handled by these tools. Problematic changes which cause
9548 <prgn>dpkg-source</prgn> to halt with an error when
9549 building the source package are:
9550 <list compact="compact">
9551 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9553 <item><p>Changing the targets of symbolic links.</p>
9555 <item><p>Creating directories, other than <file>debian</file>.</p>
9557 <item><p>Changes to the contents of binary files.</p></item>
9558 </list> Changes which cause <prgn>dpkg-source</prgn> to
9559 print a warning but continue anyway are:
9560 <list compact="compact">
9563 Removing files, directories or symlinks.
9565 Renaming a file is not treated specially - it is
9566 seen as the removal of the old file (which
9567 generates a warning, but is otherwise ignored),
9568 and the creation of the new one.
9574 Changed text files which are missing the usual final
9575 newline (either in the original or the modified
9580 Changes which are not represented, but which are not detected by
9581 <prgn>dpkg-source</prgn>, are:
9582 <list compact="compact">
9583 <item><p>Changing the permissions of files (other than
9584 <file>debian/rules</file>) and directories.</p></item>
9589 The <file>debian</file> directory and <file>debian/rules</file>
9590 are handled specially by <prgn>dpkg-source</prgn> - before
9591 applying the changes it will create the <file>debian</file>
9592 directory, and afterwards it will make
9593 <file>debian/rules</file> world-exectuable.
9599 <appendix id="pkg-controlfields">
9600 <heading>Control files and their fields (from old Packaging Manual)</heading>
9603 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9604 data in a common format, known as control files. Binary and
9605 source packages have control data as do the <file>.changes</file>
9606 files which control the installation of uploaded files, and
9607 <prgn>dpkg</prgn>'s internal databases are in a similar
9612 <heading>Syntax of control files</heading>
9615 See <ref id="controlsyntax">.
9619 It is important to note that there are several fields which
9620 are optional as far as <prgn>dpkg</prgn> and the related
9621 tools are concerned, but which must appear in every Debian
9622 package, or whose omission may cause problems.
9627 <heading>List of fields</heading>
9630 See <ref id="controlfieldslist">.
9634 This section now contains only the fields that didn't belong
9635 to the Policy manual.
9638 <sect1 id="pkg-f-Filename">
9639 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9642 These fields in <tt>Packages</tt> files give the
9643 filename(s) of (the parts of) a package in the
9644 distribution directories, relative to the root of the
9645 Debian hierarchy. If the package has been split into
9646 several parts the parts are all listed in order, separated
9651 <sect1 id="pkg-f-Size">
9652 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9655 These fields in <file>Packages</file> files give the size (in
9656 bytes, expressed in decimal) and MD5 checksum of the
9657 file(s) which make(s) up a binary package in the
9658 distribution. If the package is split into several parts
9659 the values for the parts are listed in order, separated by
9664 <sect1 id="pkg-f-Status">
9665 <heading><tt>Status</tt></heading>
9668 This field in <prgn>dpkg</prgn>'s status file records
9669 whether the user wants a package installed, removed or
9670 left alone, whether it is broken (requiring
9671 reinstallation) or not and what its current state on the
9672 system is. Each of these pieces of information is a
9677 <sect1 id="pkg-f-Config-Version">
9678 <heading><tt>Config-Version</tt></heading>
9681 If a package is not installed or not configured, this
9682 field in <prgn>dpkg</prgn>'s status file records the last
9683 version of the package which was successfully
9688 <sect1 id="pkg-f-Conffiles">
9689 <heading><tt>Conffiles</tt></heading>
9692 This field in <prgn>dpkg</prgn>'s status file contains
9693 information about the automatically-managed configuration
9694 files held by a package. This field should <em>not</em>
9695 appear anywhere in a package!
9700 <heading>Obsolete fields</heading>
9703 These are still recognised by <prgn>dpkg</prgn> but should
9704 not appear anywhere any more.
9706 <taglist compact="compact">
9708 <tag><tt>Revision</tt></tag>
9709 <tag><tt>Package-Revision</tt></tag>
9710 <tag><tt>Package_Revision</tt></tag>
9712 The Debian revision part of the package version was
9713 at one point in a separate control file field. This
9714 field went through several names.
9717 <tag><tt>Recommended</tt></tag>
9718 <item>Old name for <tt>Recommends</tt>.</item>
9720 <tag><tt>Optional</tt></tag>
9721 <item>Old name for <tt>Suggests</tt>.</item>
9723 <tag><tt>Class</tt></tag>
9724 <item>Old name for <tt>Priority</tt>.</item>
9733 <appendix id="pkg-conffiles">
9734 <heading>Configuration file handling (from old Packaging Manual)</heading>
9737 <prgn>dpkg</prgn> can do a certain amount of automatic
9738 handling of package configuration files.
9742 Whether this mechanism is appropriate depends on a number of
9743 factors, but basically there are two approaches to any
9744 particular configuration file.
9748 The easy method is to ship a best-effort configuration in the
9749 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9750 handle updates. If the user is unlikely to want to edit the
9751 file, but you need them to be able to without losing their
9752 changes, and a new package with a changed version of the file
9753 is only released infrequently, this is a good approach.
9757 The hard method is to build the configuration file from
9758 scratch in the <prgn>postinst</prgn> script, and to take the
9759 responsibility for fixing any mistakes made in earlier
9760 versions of the package automatically. This will be
9761 appropriate if the file is likely to need to be different on
9765 <sect><heading>Automatic handling of configuration files by
9770 A package may contain a control area file called
9771 <tt>conffiles</tt>. This file should be a list of filenames
9772 of configuration files needing automatic handling, separated
9773 by newlines. The filenames should be absolute pathnames,
9774 and the files referred to should actually exist in the
9779 When a package is upgraded <prgn>dpkg</prgn> will process
9780 the configuration files during the configuration stage,
9781 shortly before it runs the package's <prgn>postinst</prgn>
9786 For each file it checks to see whether the version of the
9787 file included in the package is the same as the one that was
9788 included in the last version of the package (the one that is
9789 being upgraded from); it also compares the version currently
9790 installed on the system with the one shipped with the last
9795 If neither the user nor the package maintainer has changed
9796 the file, it is left alone. If one or the other has changed
9797 their version, then the changed version is preferred - i.e.,
9798 if the user edits their file, but the package maintainer
9799 doesn't ship a different version, the user's changes will
9800 stay, silently, but if the maintainer ships a new version
9801 and the user hasn't edited it the new version will be
9802 installed (with an informative message). If both have
9803 changed their version the user is prompted about the problem
9804 and must resolve the differences themselves.
9808 The comparisons are done by calculating the MD5 message
9809 digests of the files, and storing the MD5 of the file as it
9810 was included in the most recent version of the package.
9814 When a package is installed for the first time
9815 <prgn>dpkg</prgn> will install the file that comes with it,
9816 unless that would mean overwriting a file already on the
9821 However, note that <prgn>dpkg</prgn> will <em>not</em>
9822 replace a conffile that was removed by the user (or by a
9823 script). This is necessary because with some programs a
9824 missing file produces an effect hard or impossible to
9825 achieve in another way, so that a missing file needs to be
9826 kept that way if the user did it.
9830 Note that a package should <em>not</em> modify a
9831 <prgn>dpkg</prgn>-handled conffile in its maintainer
9832 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9833 the user confusing and possibly dangerous options for
9834 conffile update when the package is upgraded.</p>
9837 <sect><heading>Fully-featured maintainer script configuration
9842 For files which contain site-specific information such as
9843 the hostname and networking details and so forth, it is
9844 better to create the file in the package's
9845 <prgn>postinst</prgn> script.
9849 This will typically involve examining the state of the rest
9850 of the system to determine values and other information, and
9851 may involve prompting the user for some information which
9852 can't be obtained some other way.
9856 When using this method there are a couple of important
9857 issues which should be considered:
9861 If you discover a bug in the program which generates the
9862 configuration file, or if the format of the file changes
9863 from one version to the next, you will have to arrange for
9864 the postinst script to do something sensible - usually this
9865 will mean editing the installed configuration file to remove
9866 the problem or change the syntax. You will have to do this
9867 very carefully, since the user may have changed the file,
9868 perhaps to fix the very problem that your script is trying
9869 to deal with - you will have to detect these situations and
9870 deal with them correctly.
9874 If you do go down this route it's probably a good idea to
9875 make the program that generates the configuration file(s) a
9876 separate program in <file>/usr/sbin</file>, by convention called
9877 <file><var>package</var>config</file> and then run that if
9878 appropriate from the post-installation script. The
9879 <tt><var>package</var>config</tt> program should not
9880 unquestioningly overwrite an existing configuration - if its
9881 mode of operation is geared towards setting up a package for
9882 the first time (rather than any arbitrary reconfiguration
9883 later) you should have it check whether the configuration
9884 already exists, and require a <tt>--force</tt> flag to
9885 overwrite it.</p></sect>
9888 <appendix id="pkg-alternatives"><heading>Alternative versions of
9889 an interface - <prgn>update-alternatives</prgn> (from old
9894 When several packages all provide different versions of the
9895 same program or file it is useful to have the system select a
9896 default, but to allow the system administrator to change it
9897 and have their decisions respected.
9901 For example, there are several versions of the <prgn>vi</prgn>
9902 editor, and there is no reason to prevent all of them from
9903 being installed at once, each under their own name
9904 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9905 Nevertheless it is desirable to have the name <tt>vi</tt>
9906 refer to something, at least by default.
9910 If all the packages involved cooperate, this can be done with
9911 <prgn>update-alternatives</prgn>.
9915 Each package provides its own version under its own name, and
9916 calls <prgn>update-alternatives</prgn> in its postinst to
9917 register its version (and again in its prerm to deregister
9922 See the manpage <manref name="update-alternatives"
9923 section="8"> for details.
9927 If <prgn>update-alternatives</prgn> does not seem appropriate
9928 you may wish to consider using diversions instead.</p>
9931 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9932 package's version of a file (from old Packaging Manual)
9936 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9937 when it reinstalls the package it belongs to, and to have it
9938 put the file from the package somewhere else instead.
9942 This can be used locally to override a package's version of a
9943 file, or by one package to override another's version (or
9944 provide a wrapper for it).
9948 Before deciding to use a diversion, read <ref
9949 id="pkg-alternatives"> to see if you really want a diversion
9950 rather than several alternative versions of a program.
9954 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9955 and updated by a special program <prgn>dpkg-divert</prgn>.
9956 Please see <manref name="dpkg-divert" section="8"> for full
9957 details of its operation.
9961 When a package wishes to divert a file from another, it should
9962 call <prgn>dpkg-divert</prgn> in its preinst to add the
9963 diversion and rename the existing file. For example,
9964 supposing that a <prgn>smailwrapper</prgn> package wishes to
9965 install a wrapper around <file>/usr/sbin/smail</file>:
9967 if [ install = "$1" ]; then
9968 dpkg-divert --package smailwrapper --add --rename \
9969 --divert /usr/sbin/smail.real /usr/sbin/smail
9971 </example> Testing <tt>$1</tt> is necessary so that the script
9972 doesn't try to add the diversion again when
9973 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
9974 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
9975 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
9976 get installed as the true version.
9980 The postrm has to do the reverse:
9982 if [ remove = "$1" ]; then
9983 dpkg-divert --package smailwrapper --remove --rename \
9984 --divert /usr/sbin/smail.real /usr/sbin/smail
9990 Do not attempt to divert a file which is vitally important for
9991 the system's operation - when using <prgn>dpkg-divert</prgn>
9992 there is a time, after it has been diverted but before
9993 <prgn>dpkg</prgn> has installed the new version, when the file
9999 <!-- vim:set ai et sts=2 sw=2 tw=76: -->