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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy" id="http://packages.debian.org/debian-policy"></package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>.
168 Also available from the same directory are several other
169 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
170 and <file>policy.ps.gz</file>.
174 The <package>debian-policy</package> package also includes the file
175 <file>upgrading-checklist.txt</file> which indicates policy
176 changes between versions of this document.
181 <heading>Authors and Maintainers</heading>
184 Originally called "Debian GNU/Linux Policy Manual", this
185 manual was initially written in 1996 by Ian Jackson.
186 It was revised on November 27th, 1996 by David A. Morris.
187 Christian Schwarz added new sections on March 15th, 1997,
188 and reworked/restructured it in April-July 1997.
189 Christoph Lameter contributed the "Web Standard".
190 Julian Gilbey largely restructured it in 2001.
194 Since September 1998, the responsibility for the contents of
195 this document lies on the <url name="debian-policy mailing list"
196 id="mailto:debian-policy@lists.debian.org">. Proposals
197 are discussed there and inserted into policy after a certain
198 consensus is established.
199 <!-- insert shameless policy-process plug here eventually -->
200 The actual editing is done by a group of maintainers that have
201 no editorial powers. These are the current maintainers:
204 <item>Julian Gilbey</item>
205 <item>Branden Robinson</item>
206 <item>Josip Rodin</item>
207 <item>Manoj Srivastava</item>
212 While the authors of this document have tried hard to avoid
213 typos and other errors, these do still occur. If you discover
214 an error in this manual or if you want to give any
215 comments, suggestions, or criticisms please send an email to
216 the Debian Policy List,
217 <email>debian-policy@lists.debian.org</email>, or submit a
218 bug report against the <tt>debian-policy</tt> package.
222 Please do not try to reach the individual authors or maintainers
223 of the Policy Manual regarding changes to the Policy.
228 <heading>Related documents</heading>
231 There are several other documents other than this Policy Manual
232 that are necessary to fully understand some Debian policies and
237 The external "sub-policy" documents are referred to in:
238 <list compact="compact">
239 <item><ref id="fhs"></item>
240 <item><ref id="virtual_pkg"></item>
241 <item><ref id="menus"></item>
242 <item><ref id="mime"></item>
243 <item><ref id="perl"></item>
244 <item><ref id="maintscriptprompt"></item>
245 <item><ref id="emacs"></item>
250 In addition to those, which carry the weight of policy, there
251 is the Debian Developer's Reference. This document describes
252 procedures and resources for Debian developers, but it is
253 <em>not</em> normative; rather, it includes things that don't
254 belong in 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 the non-us archive is located in a country where
559 patenting algorithms is not allowed.
563 A package depends on another package which is distributed
564 via the non-us server has to be stored on the non-us
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of
575 its copyright and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Subsections</heading>
653 The packages in the sections <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further
655 into <em>subsections</em> to simplify handling.
659 The section and subsection for each package should be
660 specified in the package's <tt>Section</tt> control
661 record (see <ref id="f-Section">).
662 However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
668 <em>subsection</em> if the package is in the
669 <em>main</em> section,
672 <em>section/subsection</em> if the package is in
673 the <em>contrib</em> or <em>non-free</em> section,
677 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
678 <tt>non-US/non-free</tt> if the package is in
679 <em>non-US/main</em>, <em>non-US/contrib</em> or
680 <em>non-US/non-free</em> respectively.
686 The Debian archive maintainers provide the authoritative
687 list of subsections. At present, they are:
688 <em>admin</em>, <em>base</em>, <em>comm</em>,
689 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
690 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
691 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
692 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
693 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
694 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
695 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
696 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
697 <em>science</em>, <em>shells</em>,
698 <em>sound</em>, <em>tex</em>, <em>text</em>,
699 <em>utils</em>, <em>web</em>, <em>x11</em>.
703 <sect id="priorities">
704 <heading>Priorities</heading>
707 Each package should have a <em>priority</em> value, which is
708 included in the package's <em>control record</em>
709 (see <ref id="f-Priority">).
710 This information is used by the Debian package management tools to
711 separate high-priority packages from less-important packages.
715 The following <em>priority levels</em> are recognised by the
716 Debian package management tools.
718 <tag><tt>required</tt></tag>
720 Packages which are necessary for the proper
721 functioning of the system. You must not remove these
722 packages or your system may become totally broken and
723 you may not even be able to use <prgn>dpkg</prgn> to
724 put things back. Systems with only the
725 <tt>required</tt> packages are probably unusable, but
726 they do have enough functionality to allow the
727 sysadmin to boot and install more software.
729 <tag><tt>important</tt></tag>
731 Important programs, including those which one would
732 expect to find on any Unix-like system. If the
733 expectation is that an experienced Unix person who
734 found it missing would say "What on earth is going on,
735 where is <prgn>foo</prgn>?", it must be an
736 <tt>important</tt> package.<footnote>
737 This is an important criterion because we are
738 trying to produce, amongst other things, a free
741 Other packages without which the system will not run
742 well or be usable must also have priority
743 <tt>important</tt>. This does
744 <em>not</em> include Emacs, the X Window System, TeX
745 or any other large applications. The
746 <tt>important</tt> packages are just a bare minimum of
747 commonly-expected and necessary tools.
749 <tag><tt>standard</tt></tag>
751 These packages provide a reasonably small but not too
752 limited character-mode system. This is what will be
753 installed by default if the user doesn't select anything
754 else. It doesn't include many large applications.
756 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
767 <tag><tt>extra</tt></tag>
769 This contains all packages that conflict with others
770 with required, important, standard or optional
771 priorities, or are only likely to be useful if you
772 already know what they are or have specialised
779 Packages must not depend on packages with lower priority
780 values (excluding build-time dependencies). In order to
781 ensure this, the priorities of one or more packages may need
790 <heading>Binary packages</heading>
793 The Debian GNU/Linux distribution is based on the Debian
794 package management system, called <prgn>dpkg</prgn>. Thus,
795 all packages in the Debian distribution must be provided
796 in the <tt>.deb</tt> file format.
800 <heading>The package name</heading>
803 Every package must have a name that's unique within the Debian
808 The package name is included in the control field
809 <tt>Package</tt>, the format of which is described
810 in <ref id="f-Package">.
811 The package name is also included as a part of the file name
812 of the <tt>.deb</tt> file.
817 <heading>The version of a package</heading>
820 Every package has a version number recorded in its
821 <tt>Version</tt> control file field, described in
822 <ref id="f-Version">.
826 The package management system imposes an ordering on version
827 numbers, so that it can tell whether packages are being up- or
828 downgraded and so that package system front end applications
829 can tell whether a package it finds available is newer than
830 the one installed on the system. The version number format
831 has the most significant parts (as far as comparison is
832 concerned) at the beginning.
836 If an upstream package has problematic version numbers they
837 should be converted to a sane form for use in the
838 <tt>Version</tt> field.
842 <heading>Version numbers based on dates</heading>
845 In general, Debian packages should use the same version
846 numbers as the upstream sources.
850 However, in some cases where the upstream version number is
851 based on a date (e.g., a development "snapshot" release) the
852 package management system cannot handle these version
853 numbers without epochs. For example, dpkg will consider
854 "96May01" to be greater than "96Dec24".
858 To prevent having to use epochs for every new upstream
859 version, the date based portion of the version number
860 should be changed to the following format in such cases:
861 "19960501", "19961224". It is up to the maintainer whether
862 they want to bother the upstream maintainer to change
863 the version numbers upstream, too.
867 Note that other version formats based on dates which are
868 parsed correctly by the package management system should
869 <em>not</em> be changed.
873 Native Debian packages (i.e., packages which have been
874 written especially for Debian) whose version numbers include
875 dates should always use the "YYYYMMDD" format.
882 <heading>The maintainer of a package</heading>
885 Every package must have a Debian maintainer (the
886 maintainer may be one person or a group of people
887 reachable from a common email address, such as a mailing
888 list). The maintainer is responsible for ensuring that
889 the package is placed in the appropriate distributions.
893 The maintainer must be specified in the
894 <tt>Maintainer</tt> control field with their correct name
895 and a working email address. If one person maintains
896 several packages, they should try to avoid having
897 different forms of their name and email address in
898 the <tt>Maintainer</tt> fields of those packages.
902 The format of the <tt>Maintainer</tt> control field is
903 described in <ref id="f-Maintainer">.
907 If the maintainer of a package quits from the Debian
908 project, "Debian QA Group"
909 <email>packages@qa.debian.org</email> takes over the
910 maintainership of the package until someone else
911 volunteers for that task. These packages are called
912 <em>orphaned packages</em>.<footnote>
913 The detailed procedure for doing this gracefully can
914 be found in the Debian Developer's Reference,
915 see <ref id="related">.
920 <sect id="descriptions">
921 <heading>The description of a package</heading>
924 Every Debian package must have an extended description
925 stored in the appropriate field of the control record.
926 The technical information about the format of the
927 <tt>Description</tt> field is in <ref id="f-Description">.
931 The description should describe the package (the program) to a
932 user (system administrator) who has never met it before so that
933 they have enough information to decide whether they want to
934 install it. This description should not just be copied verbatim
935 from the program's documentation.
939 Put important information first, both in the synopsis and
940 extended description. Sometimes only the first part of the
941 synopsis or of the description will be displayed. You can
942 assume that there will usually be a way to see the whole
943 extended description.
947 The description should also give information about the
948 significant dependencies and conflicts between this package
949 and others, so that the user knows why these dependencies and
950 conflicts have been declared.
954 Instructions for configuring or using the package should
955 not be included (that is what installation scripts,
956 manual pages, info files, etc., are for). Copyright
957 statements and other administrivia should not be included
958 either (that is what the copyright file is for).
961 <sect1 id="synopsis"><heading>The single line synopsis</heading>
964 The single line synopsis should be kept brief - certainly
969 Do not include the package name in the synopsis line. The
970 display software knows how to display this already, and you
971 do not need to state it. Remember that in many situations
972 the user may only see the synopsis line - make it as
973 informative as you can.
978 <sect1 id="extendeddesc"><heading>The extended description</heading>
981 Do not try to continue the single line synopsis into the
982 extended description. This will not work correctly when
983 the full description is displayed, and makes no sense
984 where only the summary (the single line synopsis) is
989 The extended description should describe what the package
990 does and how it relates to the rest of the system (in terms
991 of, for example, which subsystem it is which part of).
995 The description field needs to make sense to anyone, even
996 people who have no idea about any of the things the
997 package deals with.<footnote>
998 The blurb that comes with a program in its
999 announcements and/or <prgn>README</prgn> files is
1000 rarely suitable for use in a description. It is
1001 usually aimed at people who are already in the
1002 community where the package is used.
1011 <heading>Dependencies</heading>
1014 Every package must specify the dependency information
1015 about other packages that are required for the first to
1020 For example, a dependency entry must be provided for any
1021 shared libraries required by a dynamically-linked executable
1022 binary in a package.
1026 Packages are not required to declare any dependencies they
1027 have on other packages which are marked <tt>Essential</tt>
1028 (see below), and should not do so unless they depend on a
1029 particular version of that package.
1033 Sometimes, a package requires another package to be installed
1034 <em>and</em> configured before it can be installed. In this
1035 case, you must specify a <tt>Pre-Depends</tt> entry for
1040 You should not specify a <tt>Pre-Depends</tt> entry for a
1041 package before this has been discussed on the
1042 <tt>debian-devel</tt> mailing list and a consensus about
1043 doing that has been reached.
1047 The format of the package interrelationship control fields is
1048 described in <ref id="relationships">.
1052 <sect id="virtual_pkg">
1053 <heading>Virtual packages</heading>
1056 Sometimes, there are several packages which offer
1057 more-or-less the same functionality. In this case, it's
1058 useful to define a <em>virtual package</em> whose name
1059 describes that common functionality. (The virtual
1060 packages only exist logically, not physically; that's why
1061 they are called <em>virtual</em>.) The packages with this
1062 particular function will then <em>provide</em> the virtual
1063 package. Thus, any other package requiring that function
1064 can simply depend on the virtual package without having to
1065 specify all possible packages individually.
1069 All packages should use virtual package names where
1070 appropriate, and arrange to create new ones if necessary.
1071 They should not use virtual package names (except privately,
1072 amongst a cooperating group of packages) unless they have
1073 been agreed upon and appear in the list of virtual package
1074 names. (See also <ref id="virtual">)
1078 The latest version of the authoritative list of virtual
1079 package names can be found in the <tt>debian-policy</tt> package.
1080 It is also available from the Debian web mirrors at
1081 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1082 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1086 The procedure for updating the list is described in the preface
1093 <heading>Base system</heading>
1096 The <tt>base system</tt> is a minimum subset of the Debian
1097 GNU/Linux system that is installed before everything else
1098 on a new system. Thus, only very few packages are allowed
1099 to go into the <tt>base</tt> section to keep the required
1100 disk usage very small.
1104 Most of these packages will have the priority value
1105 <tt>required</tt> or at least <tt>important</tt>, and many
1106 of them will be tagged <tt>essential</tt> (see below).
1111 <heading>Essential packages</heading>
1114 Some packages are tagged <tt>essential</tt> for a system
1115 using the <tt>Essential</tt> control file field.
1116 The format of the <tt>Essential</tt> control field is
1117 described in <ref id="f-Essential">.
1121 Since these packages cannot be easily removed (one has to
1122 specify an extra <em>force option</em> to
1123 <prgn>dpkg</prgn> to do so), this flag must not be used
1124 unless absolutely necessary. A shared library package
1125 must not be tagged <tt>essential</tt>; dependencies will
1126 prevent its premature removal, and we need to be able to
1127 remove it when it has been superseded.
1131 Since dpkg will not prevent upgrading of other packages
1132 while an <tt>essential</tt> package is in an unconfigured
1133 state, all <tt>essential</tt> packages must supply all of
1134 their core functionality even when unconfigured. If the
1135 package cannot satisfy this requirement it must not be
1136 tagged as essential, and any packages depending on this
1137 package must instead have explicit dependency fields as
1142 You must not tag any packages <tt>essential</tt> before
1143 this has been discussed on the <tt>debian-devel</tt>
1144 mailing list and a consensus about doing that has been
1150 <heading>Tasks</heading>
1153 The Debian install process allows the user to choose from
1154 a number of common tasks which a Debian system can be used to
1155 perform. Selecting a task with <prgn>tasksel</prgn> causes
1156 a set of packages that are useful in performing that task to be
1161 This set of packages is all available packages which have the
1162 name of the selected task in the <tt>Task</tt> field of their
1163 control file. The format of this field is a list of tasks,
1164 separated by commas.
1168 You should not tag any packages as belonging to a task
1169 before this has been discussed on the
1170 <em>debian-devel</em> mailing list and a consensus about
1171 doing that has been reached.
1175 For third parties (and historical reasons), tasksel also
1176 supports constructing tasks based on <em>task
1177 packages</em>. These are packages whose names begin with
1178 <em>task-</em>. Task packages should not be included in the
1183 <sect id="maintscripts">
1184 <heading>Maintainer Scripts</heading>
1187 The package installation scripts should avoid producing
1188 output which is unnecessary for the user to see and
1189 should rely on <prgn>dpkg</prgn> to stave off boredom on
1190 the part of a user installing many packages. This means,
1191 amongst other things, using the <tt>--quiet</tt> option on
1192 <prgn>install-info</prgn>.
1196 Errors which occur during the execution of an installation
1197 script must be checked and the installation must not
1198 continue after an error.
1202 Note that in general <ref id="scripts"> applies to package
1203 maintainer scripts, too.
1207 You should not use <prgn>dpkg-divert</prgn> on a file
1208 belonging to another package without consulting the
1209 maintainer of that package first.
1213 All packages which supply an instance of a common command
1214 name (or, in general, filename) should generally use
1215 <prgn>update-alternatives</prgn>, so that they may be
1216 installed together. If <prgn>update-alternatives</prgn>
1217 is not used, then each package must use
1218 <tt>Conflicts</tt> to ensure that other packages are
1219 de-installed. (In this case, it may be appropriate to
1220 specify a conflict against earlier versions of something
1221 that previously did not use
1222 <prgn>update-alternatives</prgn>; this is an exception to
1223 the usual rule that versioned conflicts should be
1227 <sect1 id="maintscriptprompt">
1228 <heading>Prompting in maintainer scripts</heading>
1230 Package maintainer scripts may prompt the user if
1231 necessary. Prompting should be done by communicating
1232 through a program, such as <prgn>debconf</prgn>, which
1233 conforms to the Debian Configuration management
1234 specification, version 2 or higher. Prompting the user by
1235 other means, such as by hand<footnote>
1236 From the Jargon file: by hand 2. By extension,
1237 writing code which does something in an explicit or
1238 low-level way for which a presupplied library
1239 (<em>debconf, in this instance</em>) routine ought
1240 to have been available.
1241 </footnote>, is now deprecated.
1245 The Debian Configuration management specification is included
1246 in the <file>debconf_specification</file> files in the
1247 <package>debian-policy</package> package.
1248 It is also available from the Debian web mirrors at
1249 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1250 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1254 Packages which use the Debian Configuration management
1255 specification may contain an additional
1256 <prgn>config</prgn> script and a <tt>templates</tt>
1257 file in their control archive<footnote>
1258 The control.tar.gz inside the .deb.
1259 See <manref name="deb" section="5">.
1261 The <prgn>config</prgn> script might be run before the
1262 <prgn>preinst</prgn> script, and before the package is unpacked
1263 or any of its dependencies or pre-dependancies are satisfied.
1264 Therefore it must work using only the tools present in
1265 <em>essential</em> packages.<footnote>
1266 <package>Debconf</package> or another tool that
1267 implements the Debian Configuration management
1268 specification will also be installed, and any
1269 versioned dependencies on it will be satisfied
1270 before preconfiguration begins.
1275 Packages should try to minimize the amount of prompting
1276 they need to do, and they should ensure that the user
1277 will only ever be asked each question once. This means
1278 that packages should try to use appropriate shared
1279 configuration files (such as <file>/etc/papersize</file> and
1280 <file>/etc/news/server</file>), and shared
1281 <package>debconf</package> variables rather than each
1282 prompting for their own list of required pieces of
1287 It also means that an upgrade should not ask the same
1288 questions again, unless the user has used
1289 <tt>dpkg --purge</tt> to remove the package's configuration.
1290 The answers to configuration questions should be stored in an
1291 appropriate place in <file>/etc</file> so that the user can
1292 modify them, and how this has been done should be
1297 If a package has a vitally important piece of
1298 information to pass to the user (such as "don't run me
1299 as I am, you must edit the following configuration files
1300 first or you risk your system emitting badly-formatted
1301 messages"), it should display this in the
1302 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1303 prompt the user to hit return to acknowledge the
1304 message. Copyright messages do not count as vitally
1305 important (they belong in
1306 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1307 neither do instructions on how to use a program (these
1308 should be in on-line documentation, where all the users
1313 Any necessary prompting should almost always be confined
1314 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1315 script. If it is done in the <prgn>postinst</prgn>, it
1316 should be protected with a conditional so that
1317 unnecessary prompting doesn't happen if a package's
1318 installation fails and the <prgn>postinst</prgn> is
1319 called with <tt>abort-upgrade</tt>,
1320 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1330 <heading>Source packages</heading>
1332 <sect id="standardsversion">
1333 <heading>Standards conformance</heading>
1336 Source packages should specify the most recent version number
1337 of this policy document with which your package complied
1338 when it was last updated.
1342 This information may be used to file bug reports
1343 automatically if your package becomes too much out of date.
1347 The version is specified in the <tt>Standards-Version</tt>
1349 The format of the <tt>Standards-Version</tt> field is
1350 described in <ref id="f-Standards-Version">.
1354 You should regularly, and especially if your package has
1355 become out of date, check for the newest Policy Manual
1356 available and update your package, if necessary. When your
1357 package complies with the new standards you should update the
1358 <tt>Standards-Version</tt> source package field and
1359 release it.<footnote>
1360 See the file <file>upgrading-checklist</file> for
1361 information about policy which has changed between
1362 different versions of this document.
1368 <sect id="pkg-relations">
1369 <heading>Package relationships</heading>
1372 Source packages should specify which binary packages they
1373 require to be installed or not to be installed in order to
1374 build correctly. For example, if building a package
1375 requires a certain compiler, then the compiler should be
1376 specified as a build-time dependency.
1380 It is not necessary to explicitly specify build-time
1381 relationships on a minimal set of packages that are always
1382 needed to compile, link and put in a Debian package a
1383 standard "Hello World!" program written in C or C++. The
1384 required packages are called <em>build-essential</em>, and
1385 an informational list can be found in
1386 <file>/usr/share/doc/build-essential/list</file> (which is
1387 contained in the <tt>build-essential</tt>
1390 <list compact="compact">
1392 This allows maintaining the list separately
1393 from the policy documents (the list does not
1394 need the kind of control that the policy
1398 Having a separate package allows one to install
1399 the build-essential packages on a machine, as
1400 well as allowing other packages such as tasks to
1401 require installation of the build-essential
1402 packages using the depends relation.
1405 The separate package allows bug reports against
1406 the list to be categorized separately from
1407 the policy management process in the BTS.
1414 When specifying the set of build-time dependencies, one
1415 should list only those packages explicitly required by the
1416 build. It is not necessary to list packages which are
1417 required merely because some other package in the list of
1418 build-time dependencies depends on them.<footnote>
1419 The reason for this is that dependencies change, and
1420 you should list all those packages, and <em>only</em>
1421 those packages that <em>you</em> need directly. What
1422 others need is their business. For example, if you
1423 only link against <file>libimlib</file>, you will need to
1424 build-depend on <package>libimlib2-dev</package> but
1425 not against any <tt>libjpeg*</tt> packages, even
1426 though <tt>libimlib2-dev</tt> currently depends on
1427 them: installation of <package>libimlib2-dev</package>
1428 will automatically ensure that all of its run-time
1429 dependencies are satisfied.
1434 If build-time dependencies are specified, it must be
1435 possible to build the package and produce working binaries
1436 on a system with only essential and build-essential
1437 packages installed and also those required to satisfy the
1438 build-time relationships (including any implied
1439 relationships). In particular, this means that version
1440 clauses should be used rigorously in build-time
1441 relationships so that one cannot produce bad or
1442 inconsistently configured packages when the relationships
1443 are properly satisfied.
1447 <ref id="relationships"> explains the technical details.
1452 <heading>Changes to the upstream sources</heading>
1455 If changes to the source code are made that are not
1456 specific to the needs of the Debian system, they should be
1457 sent to the upstream authors in whatever form they prefer
1458 so as to be included in the upstream version of the
1463 If you need to configure the package differently for
1464 Debian or for Linux, and the upstream source doesn't
1465 provide a way to do so, you should add such configuration
1466 facilities (for example, a new <prgn>autoconf</prgn> test
1467 or <tt>#define</tt>) and send the patch to the upstream
1468 authors, with the default set to the way they originally
1469 had it. You can then easily override the default in your
1470 <file>debian/rules</file> or wherever is appropriate.
1474 You should make sure that the <prgn>configure</prgn> utility
1475 detects the correct architecture specification string
1476 (refer to <ref id="arch-spec"> for details).
1480 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1481 <prgn>configure</prgn> scripts are used, you should edit the
1482 <file>.in</file> files rather than editing the
1483 <prgn>Makefile</prgn> directly. This allows the user to
1484 reconfigure the package if necessary. You should
1485 <em>not</em> configure the package and edit the generated
1486 <prgn>Makefile</prgn>! This makes it impossible for someone
1487 else to later reconfigure the package without losing the
1493 <sect id="dpkgchangelog">
1494 <heading>Debian changelog: <file>debian/changelog</file></heading>
1497 Changes in the Debian version of the package should be
1498 briefly explained in the Debian changelog file
1499 <file>debian/changelog</file>. This includes modifications
1500 made in the Debian package compared to the upstream one
1501 as well as other changes and updates to the package.
1503 Although there is nothing stopping an author who is also
1504 the Debian maintainer from using this changelog for all
1505 their changes, it will have to be renamed if the Debian
1506 and upstream maintainers become different people. In such
1507 a case, however, it might be better to maintain the package
1508 as a non-native package.
1513 Mistakes in changelogs are usually best rectified by making
1514 a new changelog entry rather than "rewriting history" by
1515 editing old changelog entries.
1519 The format of the <file>debian/changelog</file> allows the
1520 package building tools to discover which version of the package
1521 is being built and find out other release-specific information.
1525 That format is a series of entries like this:
1527 <example compact="compact">
1528 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1530 [optional blank line(s), stripped]
1532 * <var>change details</var>
1533 <var>more change details</var>
1535 [blank line(s), included in output of dpkg-parsechangelog]
1537 * <var>even more change details</var>
1539 [optional blank line(s), stripped]
1541 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1546 <var>package</var> and <var>version</var> are the source
1547 package name and version number.
1551 <var>distribution(s)</var> lists the distributions where
1552 this version should be installed when it is uploaded - it
1553 is copied to the <tt>Distribution</tt> field in the
1554 <file>.changes</file> file. See <ref id="f-Distribution">.
1558 <var>urgency</var> is the value for the <tt>Urgency</tt>
1559 field in the <file>.changes</file> file for the upload
1560 (see <ref id="f-Urgency">). It is not possible to specify
1561 an urgency containing commas; commas are used to separate
1562 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1563 <prgn>dpkg</prgn> changelog format (though there is
1564 currently only one useful <var>keyword</var>,
1565 <tt>urgency</tt>).<footnote>
1566 Recognised urgency values are <tt>low</tt>,
1567 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1568 They have an effect on how quickly a package will be
1569 considered for inclusion into the <tt>testing</tt>
1570 distribution, and give an indication of the importance
1571 of any fixes included in this upload.
1576 The change details may in fact be any series of lines
1577 starting with at least two spaces, but conventionally each
1578 change starts with an asterisk and a separating space and
1579 continuation lines are indented so as to bring them in
1580 line with the start of the text above. Blank lines may be
1581 used here to separate groups of changes, if desired.
1585 If this upload resolves bugs recorded in the Bug Tracking
1586 System (BTS), they may be automatically closed on the
1587 inclusion of this package into the Debian archive by
1588 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1589 in the change details.<footnote>
1590 To be precise, the string should match the following
1591 Perl regular expression:
1593 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1595 Then all of the bug numbers listed will be closed by the
1596 archive maintenance script (<prgn>katie</prgn>), or in
1597 the case of an NMU, marked as fixed.
1599 This information is conveyed via the <tt>Closes</tt> field
1600 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1604 The maintainer name and email address used in the changelog
1605 should be the details of the person uploading <em>this</em>
1606 version. They are <em>not</em> necessarily those of the
1607 usual package maintainer. The information here will be
1608 copied to the <tt>Changed-By</tt> field in the
1609 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1610 and then later used to send an acknowledgement when the
1611 upload has been installed.
1615 The <var>date</var> should be in RFC822 format<footnote>
1616 This is generated by the <prgn>822-date</prgn>
1618 </footnote>; it should include the time zone specified
1619 numerically, with the time zone name or abbreviation
1620 optionally present as a comment in parentheses.
1624 The first "title" line with the package name should start
1625 at the left hand margin; the "trailer" line with the
1626 maintainer and date details should be preceded by exactly
1627 one space. The maintainer details and the date must be
1628 separated by exactly two spaces.
1632 For more information on placement of the changelog files
1633 within binary packages, please see <ref id="changelogs">.
1636 <sect1><heading>Alternative changelog formats</heading>
1639 In non-experimental packages you must use a format for
1640 <file>debian/changelog</file> which is supported by the most
1641 recent released version of <prgn>dpkg</prgn>.
1645 It is possible to use a format different from the standard
1646 one by providing a changelog parser for the format you wish
1647 to use. The parser must have an API compatible with that
1648 expected by <prgn>dpkg-genchanges</prgn> and
1649 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1652 If there is general interest in the new format, you should
1653 contact the <package>dpkg</package> maintainer to have the
1654 parser script for it included in the <prgn>dpkg</prgn>
1655 package. (You will need to agree that the parser and its
1656 man page may be distributed under the GNU GPL, just as the rest
1657 of <prgn>dpkg</prgn> is.)
1664 <heading>Error trapping in makefiles</heading>
1667 When <prgn>make</prgn> invokes a command in a makefile
1668 (including your package's upstream makefiles and
1669 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1670 means that <prgn>sh</prgn>'s usual bad error handling
1671 properties apply: if you include a miniature script as one
1672 of the commands in your makefile you'll find that if you
1673 don't do anything about it then errors are not detected
1674 and <prgn>make</prgn> will blithely continue after
1679 Every time you put more than one shell command (this
1680 includes using a loop) in a makefile command you
1681 must make sure that errors are trapped. For
1682 simple compound commands, such as changing directory and
1683 then running a program, using <tt>&&</tt> rather
1684 than semicolon as a command separator is sufficient. For
1685 more complex commands including most loops and
1686 conditionals you should include a separate <tt>set -e</tt>
1687 command at the start of every makefile command that's
1688 actually one of these miniature shell scripts.
1692 <sect id="timestamps">
1693 <heading>Time Stamps</heading>
1695 Maintainers should preserve the modification times of the
1696 upstream source files in a package, as far as is reasonably
1698 The rationale is that there is some information conveyed
1699 by knowing the age of the file, for example, you could
1700 recognize that some documentation is very old by looking
1701 at the modification time, so it would be nice if the
1702 modification time of the upstream source would be
1708 <sect id="restrictions">
1709 <heading>Restrictions on objects in source packages</heading>
1712 The source package may not contain any hard links<footnote>
1714 This is not currently detected when building source
1715 packages, but only when extracting
1719 Hard links may be permitted at some point in the
1720 future, but would require a fair amount of
1723 </footnote>, device special files, sockets or setuid or
1724 setgid files.<footnote>
1725 Setgid directories are allowed.
1730 <sect id="debianrules">
1731 <heading>Main building script: <file>debian/rules</file></heading>
1734 This file must be an executable makefile, and contains the
1735 package-specific recipes for compiling the package and
1736 building binary package(s) from the source.
1740 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1741 so that it can be invoked by saying its name rather than
1742 invoking <prgn>make</prgn> explicitly.
1746 Since an interactive <file>debian/rules</file> script makes it
1747 impossible to auto-compile that package and also makes it
1748 hard for other people to reproduce the same binary
1749 package, all <em>required targets</em> MUST be
1750 non-interactive. At a minimum, required targets are the
1751 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1752 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1753 <em>binary-indep</em>, and <em>build</em>. It also follows
1754 that any target that these targets depend on must also be
1759 The targets are as follows (required unless stated otherwise):
1761 <tag><tt>build</tt></tag>
1764 The <tt>build</tt> target should perform all the
1765 configuration and compilation of the package.
1766 If a package has an interactive pre-build
1767 configuration routine, the Debianized source package
1768 must either be built after this has taken place (so
1769 that the binary package can be built without rerunning
1770 the configuration) or the configuration routine
1771 modified to become non-interactive. (The latter is
1772 preferable if there are architecture-specific features
1773 detected by the configuration routine.)
1777 For some packages, notably ones where the same
1778 source tree is compiled in different ways to produce
1779 two binary packages, the <tt>build</tt> target
1780 does not make much sense. For these packages it is
1781 good enough to provide two (or more) targets
1782 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1783 for each of the ways of building the package, and a
1784 <tt>build</tt> target that does nothing. The
1785 <tt>binary</tt> target will have to build the
1786 package in each of the possible ways and make the
1787 binary package out of each.
1791 The <tt>build</tt> target must not do anything
1792 that might require root privilege.
1796 The <tt>build</tt> target may need to run the
1797 <tt>clean</tt> target first - see below.
1801 When a package has a configuration and build routine
1802 which takes a long time, or when the makefiles are
1803 poorly designed, or when <tt>build</tt> needs to
1804 run <tt>clean</tt> first, it is a good idea to
1805 <tt>touch build</tt> when the build process is
1806 complete. This will ensure that if <tt>debian/rules
1807 build</tt> is run again it will not rebuild the whole
1809 Another common way to do this is for <tt>build</tt>
1810 to depend on <prgn>build-stamp</prgn> and to do
1811 nothing else, and for the <prgn>build-stamp</prgn>
1812 target to do the building and to <tt>touch
1813 build-stamp</tt> on completion. This is
1814 especially useful if the build routine creates a
1815 file or directory called <tt>build</tt>; in such a
1816 case, <tt>build</tt> will need to be listed as
1817 a phony target (i.e., as a dependency of the
1818 <tt>.PHONY</tt> target). See the documentation of
1819 <prgn>make</prgn> for more information on phony
1825 <tag><tt>build-arch</tt> (optional),
1826 <tt>build-indep</tt> (optional)
1830 A package may also provide both of the targets
1831 <tt>build-arch</tt> and <tt>build-indep</tt>.
1832 The <tt>build-arch</tt> target, if provided, should
1833 perform all the configuration and compilation required
1834 for producing all architecture-dependant binary packages
1835 (those packages for which the body of the
1836 <tt>Architecture</tt> field in <tt>debian/control</tt>
1837 is not <tt>all</tt>).
1838 Similarly, the <tt>build-indep</tt> target, if
1839 provided, should perform all the configuration and
1840 compilation required for producing all
1841 architecture-independent binary packages
1842 (those packages for which the body of the
1843 <tt>Architecture</tt> field in <tt>debian/control</tt>
1845 The <tt>build</tt> target should depend on those of the
1846 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1847 are provided in the rules file.
1851 If one or both of the targets <tt>build-arch</tt> and
1852 <tt>build-indep</tt> are not provided, then invoking
1853 <file>debian/rules</file> with one of the not-provided
1854 targets as arguments should produce a exit status code
1855 of 2. Usually this is provided automatically by make
1856 if the target is missing.
1860 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1861 must not do anything that might require root privilege.
1865 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1866 <tt>binary-indep</tt>
1870 The <tt>binary</tt> target must be all that is
1871 necessary for the user to build the binary package(s)
1872 produced from this source package. It is
1873 split into two parts: <prgn>binary-arch</prgn> builds
1874 the binary packages which are specific to a particular
1875 architecture, and <tt>binary-indep</tt> builds
1876 those which are not.
1879 <tt>binary</tt> may be (and commonly is) a target with
1880 no commands which simply depends on
1881 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1884 Both <tt>binary-*</tt> targets should depend on the
1885 <tt>build</tt> target, or on the appropriate
1886 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1887 provided, so that the package is built if it has not
1888 been already. It should then create the relevant
1889 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1890 make their control files and <prgn>dpkg-deb</prgn> to
1891 build them and place them in the parent of the top
1896 Both the <tt>binary-arch</tt> and
1897 <tt>binary-indep</tt> targets <em>must</em> exist.
1898 If one of them has nothing to do (which will always be
1899 the case if the source generates only a single binary
1900 package, whether architecture-dependent or not), it
1901 must still exist and must always succeed.
1905 The <tt>binary</tt> targets must be invoked as
1907 The <prgn>fakeroot</prgn> package often allows one
1908 to build a package correctly even without being
1914 <tag><tt>clean</tt></tag>
1917 This must undo any effects that the <tt>build</tt>
1918 and <tt>binary</tt> targets may have had, except
1919 that it should leave alone any output files created in
1920 the parent directory by a run of a <tt>binary</tt>
1925 If a <tt>build</tt> file is touched at the end of
1926 the <tt>build</tt> target, as suggested above, it
1927 should be removed as the first action that
1928 <tt>clean</tt> performs, so that running
1929 <tt>build</tt> again after an interrupted
1930 <tt>clean</tt> doesn't think that everything is
1935 The <tt>clean</tt> target may need to be
1936 invoked as root if <tt>binary</tt> has been
1937 invoked since the last <tt>clean</tt>, or if
1938 <tt>build</tt> has been invoked as root (since
1939 <tt>build</tt> may create directories, for
1944 <tag><tt>get-orig-source</tt> (optional)</tag>
1947 This target fetches the most recent version of the
1948 original source package from a canonical archive site
1949 (via FTP or WWW, for example), does any necessary
1950 rearrangement to turn it into the original source
1951 tar file format described below, and leaves it in the
1956 This target may be invoked in any directory, and
1957 should take care to clean up any temporary files it
1962 This target is optional, but providing it if
1963 possible is a good idea.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1997 specification string)
2000 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2001 <tt>DEB_*_GNU_TYPE</tt>)
2004 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2005 <tt>DEB_*_GNU_TYPE</tt>)
2007 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2008 the build machine or <tt>HOST</tt> for specification of the
2013 Backward compatibility can be provided in the rules file
2014 by setting the needed variables to suitable default
2015 values; please refer to the documentation of
2016 <prgn>dpkg-architecture</prgn> for details.
2020 It is important to understand that the <tt>DEB_*_ARCH</tt>
2021 string only determines which Debian architecture we are
2022 building on or for. It should not be used to get the CPU
2023 or system information; the GNU style variables should be
2028 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2029 <sect id="substvars">
2030 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2033 When <prgn>dpkg-gencontrol</prgn>,
2034 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2035 generate control files they perform variable substitutions
2036 on their output just before writing it. Variable
2037 substitutions have the form <tt>${<var>variable</var>}</tt>.
2038 The optional file <file>debian/substvars</file> contains
2039 variable substitutions to be used; variables can also be set
2040 directly from <file>debian/rules</file> using the <tt>-V</tt>
2041 option to the source packaging commands, and certain
2042 predefined variables are also available.
2046 The <file>debian/substvars</file> file is usually generated and
2047 modified dynamically by <file>debian/rules</file> targets, in
2048 which case it must be removed by the <tt>clean</tt> target.
2052 See <manref name="dpkg-source" section="1"> for full
2053 details about source variable substitutions, including the
2054 format of <file>debian/substvars</file>.</p>
2057 <sect id="debianfiles">
2058 <heading>Generated files list: <file>debian/files</file></heading>
2061 This file is not a permanent part of the source tree; it
2062 is used while building packages to record which files are
2063 being generated. <prgn>dpkg-genchanges</prgn> uses it
2064 when it generates a <file>.changes</file> file.
2068 It should not exist in a shipped source package, and so it
2069 (and any backup files or temporary files such as
2070 <file>files.new</file><footnote>
2071 <file>files.new</file> is used as a temporary file by
2072 <prgn>dpkg-gencontrol</prgn> and
2073 <prgn>dpkg-distaddfile</prgn> - they write a new
2074 version of <tt>files</tt> here before renaming it,
2075 to avoid leaving a corrupted copy if an error
2077 </footnote>) should be removed by the
2078 <tt>clean</tt> target. It may also be wise to
2079 ensure a fresh start by emptying or removing it at the
2080 start of the <tt>binary</tt> target.
2084 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2085 package, it adds an entry to <file>debian/files</file> for the
2086 <file>.deb</file> file that will be created when <tt>dpkg-deb
2087 --build</tt> is run for that binary package. So for most
2088 packages all that needs to be done with this file is to
2089 delete it in the <tt>clean</tt> target.
2093 If a package upload includes files besides the source
2094 package and any binary packages whose control files were
2095 made with <prgn>dpkg-gencontrol</prgn> then they should be
2096 placed in the parent of the package's top-level directory
2097 and <prgn>dpkg-distaddfile</prgn> should be called to add
2098 the file to the list in <file>debian/files</file>.</p>
2104 <chapt id="controlfields">
2105 <heading>Control files and their fields</heading>
2108 The package management system manipulates data represented in
2109 a common format, known as <em>control data</em>, stored in
2110 <em>control files</em>.
2111 Control files are used for source packages, binary packages and
2112 the <file>.changes</file> files which control the installation
2113 of uploaded files<footnote>
2114 <prgn>dpkg</prgn>'s internal databases are in a similar
2119 <sect id="controlsyntax">
2120 <heading>Syntax of control files</heading>
2123 A control file consists of one or more paragraphs of
2125 The paragraphs are also sometimes referred to as stanzas.
2127 The paragraphs are separated by blank lines. Some control
2128 files allow only one paragraph; others allow several, in
2129 which case each paragraph usually refers to a different
2130 package. (For example, in source packages, the first
2131 paragraph refers to the source package, and later paragraphs
2132 refer to binary packages generated from the source.)
2136 Each paragraph consists of a series of data fields; each
2137 field consists of the field name, followed by a colon and
2138 then the data/value associated with that field. It ends at
2139 the end of the line. Horizontal whitespace (spaces and
2140 tabs) may occur immediately before or after the value and is
2141 ignored there; it is conventional to put a single space
2142 after the colon. For example, a field might be:
2143 <example compact="compact">
2146 the field name is <tt>Package</tt> and the field value
2151 Some fields' values may span several lines; in this case
2152 each continuation line must start with a space or a tab.
2153 Any trailing spaces or tabs at the end of individual
2154 lines of a field value are ignored.
2158 Except where otherwise stated, only a single line of data is
2159 allowed and whitespace is not significant in a field body.
2160 Whitespace must not appear inside names (of packages,
2161 architectures, files or anything else) or version numbers,
2162 or between the characters of multi-character version
2167 Field names are not case-sensitive, but it is usual to
2168 capitalize the field names using mixed case as shown below.
2172 Blank lines, or lines consisting only of spaces and tabs,
2173 are not allowed within field values or between fields - that
2174 would mean a new paragraph.
2179 <sect id="sourcecontrolfiles">
2180 <heading>Source package control files -- <file>debian/control</file></heading>
2183 The <file>debian/control</file> file contains the most vital
2184 (and version-independent) information about the source package
2185 and about the binary packages it creates.
2189 The first paragraph of the control file contains information about
2190 the source package in general. The subsequent sets each describe a
2191 binary package that the source tree builds.
2195 The fields in the general paragraph (the first one, for the source
2198 <list compact="compact">
2199 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2200 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2201 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2202 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2203 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2204 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2205 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2210 The fields in the binary package paragraphs are:
2212 <list compact="compact">
2213 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2214 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2215 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2216 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2217 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2218 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2219 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2224 The syntax and semantics of the fields are described below.
2230 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2231 generate control files for binary packages (see below), by
2232 <prgn>dpkg-genchanges</prgn> to generate the
2233 <tt>.changes</tt> file to accompany the upload, and by
2234 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2235 source control file as part of a source archive.
2239 The fields here may contain variable references - their
2240 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2241 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2242 when they generate output control files.
2243 See <ref id="substvars"> for details.
2248 <sect id="binarycontrolfiles">
2249 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2252 The <file>DEBIAN/control</file> file contains the most vital
2253 (and version-dependent) information about a binary package.
2257 The fields in this file are:
2259 <list compact="compact">
2260 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2261 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2262 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2263 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2264 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2265 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2266 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2267 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2268 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2269 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2275 <sect id="debiansourcecontrolfiles">
2276 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2279 This file contains a series of fields, identified and
2280 separated just like the fields in the control file of
2281 a binary package. The fields are listed below; their
2282 syntax is described above, in <ref id="pkg-controlfields">.
2284 <list compact="compact">
2285 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2286 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2287 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2288 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2289 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2290 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2291 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2292 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2293 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2294 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2299 The source package control file is generated by
2300 <prgn>dpkg-source</prgn> when it builds the source
2301 archive, from other files in the source package,
2302 described above. When unpacking, it is checked against
2303 the files and directories in the other parts of the
2309 <sect id="debianchangesfiles">
2310 <heading>Debian changes files -- <file>.changes</file></heading>
2313 The .changes files are used by the Debian archive maintenance
2314 software to process updates to packages. They contain one
2315 paragraph which contains information from the
2316 <tt>debian/control</tt> file and other data about the
2317 source package gathered via <tt>debian/changelog</tt>
2318 and <tt>debian/rules</tt>.
2322 The fields in this file are:
2324 <list compact="compact">
2325 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2326 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2327 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2328 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2329 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2330 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2333 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2335 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2337 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2343 <sect id="controlfieldslist">
2344 <heading>List of fields</heading>
2346 <sect1 id="f-Source">
2347 <heading><tt>Source</tt></heading>
2350 This field identifies the source package name.
2354 In a main source control information, a <file>.changes</file>
2355 or a <file>.dsc</file> file this may contain only the name
2356 of the source package.
2360 In the control file of a binary package it may be followed
2361 by a version number in parentheses<footnote>
2362 It is customary to leave a space after the package name
2363 if a version number is specified.
2365 This version number may be omitted (and is, by
2366 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2367 the <tt>Version</tt> field of the binary package in
2368 question. The field itself may be omitted from a binary
2369 package control file when the source package has the same
2370 name and version as the binary package.
2374 <sect1 id="f-Maintainer">
2375 <heading><tt>Maintainer</tt></heading>
2378 The package maintainer's name and email address. The name
2379 should come first, then the email address inside angle
2380 brackets <tt><></tt> (in RFC822 format).
2384 If the maintainer's name contains a full stop then the
2385 whole field will not work directly as an email address due
2386 to a misfeature in the syntax specified in RFC822; a
2387 program using this field as an address must check for this
2388 and correct the problem if necessary (for example by
2389 putting the name in round brackets and moving it to the
2390 end, and bringing the email address forward).
2394 <sect1 id="f-Uploaders">
2395 <heading><tt>Uploaders</tt></heading>
2398 List of the names and email addresses of
2399 co-maintaintainers of the package, if any. If the package
2400 has other maintainers beside the one named in the <qref
2401 id="f-Maintainer">Maintainer field</qref>, they their
2402 names and email addresses should be listed here. The
2403 format is the same as that of the Maintainer tag, and
2404 multiple entries should be comma separated. This is an
2409 <sect1 id="f-Changed-By">
2410 <heading><tt>Changed-By</tt></heading>
2413 The name and email address of the person who changed the
2414 said package. Usually the name of the maintainer.
2415 All the rules for the Maintainer field apply here, too.
2419 <sect1 id="f-Section">
2420 <heading><tt>Section</tt></heading>
2423 This field specifies an application area into which the package
2424 has been classified. See <ref id="subsections">.
2428 When it appears in the <file>debian/control</file> file,
2429 it gives the value for the subfield of the same name in
2430 the <tt>Files</tt> field of the <file>.changes</file> file.
2431 It also gives the default for the same field in the binary
2436 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2437 field in the control file of a binary package - use the
2438 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2442 <sect1 id="f-Priority">
2443 <heading><tt>Priority</tt></heading>
2446 This field represents how important that it is that the user
2447 have the package installed. See <ref id="priorities">.
2451 When it appears in the <file>debian/control</file> file,
2452 it gives the value for the subfield of the same name in
2453 the <tt>Files</tt> field of the <file>.changes</file> file.
2454 It also gives the default for the same field in the binary
2459 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2460 field in the control file of a binary package - use the
2461 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2465 <sect1 id="f-Package">
2466 <heading><tt>Package</tt></heading>
2469 The name of the binary package.
2473 Package names must consist only of lower case letters
2474 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2475 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2476 They must be at least two characters long and must start
2477 with an alphanumeric character.
2481 <sect1 id="f-Architecture">
2482 <heading><tt>Architecture</tt></heading>
2485 Depending on context and the control file used, the
2486 <tt>Architecture</tt> field can include the following sets of
2489 <item>A unique single word identifying a Debian machine
2490 architecture, see <ref id="arch-spec">.
2491 <item><tt>all</tt>, which indicates an
2492 architecture-independent package.
2493 <item><tt>any</tt>, which indicates a package available
2494 for building on any architecture.
2495 <item><tt>source</tt>, which indicates a source package.
2500 In the main <file>debian/control</file> file in the source
2501 package, or in the source package control file
2502 <file>.dsc</file>, one may specify a list of architectures
2503 separated by spaces, or the special values <tt>any</tt> or
2508 Specifying <tt>any</tt> indicates that the source package
2509 isn't dependent on any particular architecture and should
2510 compile fine on any one. The produced binary package(s)
2511 will be specific to whatever the current build architecture
2513 This is the most often used setting, and is recommended
2514 for new packages that aren't <tt>Architecture: all</tt>.
2519 Specifying a list of architectures indicates that the source
2520 will build an architecture-dependent package, and will only
2521 work correctly on the listed architectures.<footnote>
2522 This is a setting used for a minority of cases where the
2523 program is not portable. Generally, it should not be used
2529 In a <file>.changes</file> file, the <tt>Architecture</tt>
2530 field lists the architecture(s) of the package(s)
2531 currently being uploaded. This will be a list; if the
2532 source for the package is also being uploaded, the special
2533 entry <tt>source</tt> is also present.
2537 See <ref id="debianrules"> for information how to get the
2538 architecture for the build process.
2542 <sect1 id="f-Essential">
2543 <heading><tt>Essential</tt></heading>
2546 This is a boolean field which may occur only in the
2547 control file of a binary package or in a per-package fields
2548 paragraph of a main source control data file.
2552 If set to <tt>yes</tt> then the package management system
2553 will refuse to remove the package (upgrading and replacing
2554 it is still possible). The other possible value is <tt>no</tt>,
2555 which is the same as not having the field at all.
2560 <heading>Package interrelationship fields:
2561 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2562 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2563 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2567 These fields describe the package's relationships with
2568 other packages. Their syntax and semantics are described
2569 in <ref id="relationships">.</p>
2572 <sect1 id="f-Standards-Version">
2573 <heading><tt>Standards-Version</tt></heading>
2576 The most recent version of the standards (the policy
2577 manual and associated texts) with which the package
2582 The version number has four components: major and minor
2583 version number and major and minor patch level. When the
2584 standards change in a way that requires every package to
2585 change the major number will be changed. Significant
2586 changes that will require work in many packages will be
2587 signaled by a change to the minor number. The major patch
2588 level will be changed for any change to the meaning of the
2589 standards, however small; the minor patch level will be
2590 changed when only cosmetic, typographical or other edits
2591 are made which neither change the meaning of the document
2592 nor affect the contents of packages.
2596 Thus only the first three components of the policy version
2597 are significant in the <em>Standards-Version</em> control
2598 field, and so either these three components or the all
2599 four components may be specified.<footnote>
2600 In the past, people specified the full version number
2601 in the Standards-Version field, for example "2.3.0.0".
2602 Since minor patch-level changes don't introduce new
2603 policy, it was thought it would be better to relax
2604 policy and only require the first 3 components to be
2605 specified, in this example "2.3.0". All four
2606 components may still be used if someone wishes to do so.
2612 <sect1 id="f-Version">
2613 <heading><tt>Version</tt></heading>
2616 The version number of a package. The format is:
2617 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2621 The three components here are:
2623 <tag><var>epoch</var></tag>
2626 This is a single (generally small) unsigned integer. It
2627 may be omitted, in which case zero is assumed. If it is
2628 omitted then the <var>upstream_version</var> may not
2633 It is provided to allow mistakes in the version numbers
2634 of older versions of a package, and also a package's
2635 previous version numbering schemes, to be left behind.
2639 <tag><var>upstream_version</var></tag>
2642 This is the main part of the version number. It is
2643 usually the version number of the original ("upstream")
2644 package from which the <file>.deb</file> file has been made,
2645 if this is applicable. Usually this will be in the same
2646 format as that specified by the upstream author(s);
2647 however, it may need to be reformatted to fit into the
2648 package management system's format and comparison
2653 The comparison behavior of the package management system
2654 with respect to the <var>upstream_version</var> is
2655 described below. The <var>upstream_version</var>
2656 portion of the version number is mandatory.
2660 The <var>upstream_version</var> may contain only
2661 alphanumerics<footnote>
2662 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2664 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2665 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2666 start with a digit. If there is no
2667 <var>debian_revision</var> then hyphens are not allowed;
2668 if there is no <var>epoch</var> then colons are not
2673 <tag><var>debian_revision</var></tag>
2676 This part of the version number specifies the version of
2677 the Debian package based on the upstream version. It
2678 may contain only alphanumerics and the characters
2679 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2680 compared in the same way as the
2681 <var>upstream_version</var> is.
2685 It is optional; if it isn't present then the
2686 <var>upstream_version</var> may not contain a hyphen.
2687 This format represents the case where a piece of
2688 software was written specifically to be turned into a
2689 Debian package, and so there is only one "debianization"
2690 of it and therefore no revision indication is required.
2694 It is conventional to restart the
2695 <var>debian_revision</var> at <tt>1</tt> each time the
2696 <var>upstream_version</var> is increased.
2700 The package management system will break the version
2701 number apart at the last hyphen in the string (if there
2702 is one) to determine the <var>upstream_version</var> and
2703 <var>debian_revision</var>. The absence of a
2704 <var>debian_revision</var> compares earlier than the
2705 presence of one (but note that the
2706 <var>debian_revision</var> is the least significant part
2707 of the version number).
2714 The <var>upstream_version</var> and <var>debian_revision</var>
2715 parts are compared by the package management system using the
2720 The strings are compared from left to right.
2724 First the initial part of each string consisting entirely of
2725 non-digit characters is determined. These two parts (one of
2726 which may be empty) are compared lexically. If a difference
2727 is found it is returned. The lexical comparison is a
2728 comparison of ASCII values modified so that all the letters
2729 sort earlier than all the non-letters.
2733 Then the initial part of the remainder of each string which
2734 consists entirely of digit characters is determined. The
2735 numerical values of these two parts are compared, and any
2736 difference found is returned as the result of the comparison.
2737 For these purposes an empty string (which can only occur at
2738 the end of one or both version strings being compared) counts
2743 These two steps (comparing and removing initial non-digit
2744 strings and initial digit strings) are repeated until a
2745 difference is found or both strings are exhausted.
2749 Note that the purpose of epochs is to allow us to leave behind
2750 mistakes in version numbering, and to cope with situations
2751 where the version numbering scheme changes. It is
2752 <em>not</em> intended to cope with version numbers containing
2753 strings of letters which the package management system cannot
2754 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2755 silly orderings (the author of this manual has heard of a
2756 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2757 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2758 <tt>2</tt> and so forth).
2762 <sect1 id="f-Description">
2763 <heading><tt>Description</tt></heading>
2766 In a source or binary control file, the <tt>Description</tt>
2767 field contains a description of the binary package, consisting
2768 of two parts, the synopsis or the short description, and the
2769 long description. The field's format is as follows:
2774 Description: <single line synopsis>
2775 <extended description over several lines>
2780 The lines in the extended description can have these formats:
2786 Those starting with a single space are part of a paragraph.
2787 Successive lines of this form will be word-wrapped when
2788 displayed. The leading space will usually be stripped off.
2792 Those starting with two or more spaces. These will be
2793 displayed verbatim. If the display cannot be panned
2794 horizontally, the displaying program will linewrap them "hard"
2795 (i.e., without taking account of word breaks). If it can they
2796 will be allowed to trail off to the right. None, one or two
2797 initial spaces may be deleted, but the number of spaces
2798 deleted from each line will be the same (so that you can have
2799 indenting work correctly, for example).
2803 Those containing a single space followed by a single full stop
2804 character. These are rendered as blank lines. This is the
2805 <em>only</em> way to get a blank line<footnote>
2806 Completely empty lines will not be rendered as blank lines.
2807 Instead, they will cause the parser to think you're starting
2808 a whole new record in the control file, and will therefore
2809 likely abort with an error.
2814 Those containing a space, a full stop and some more characters.
2815 These are for future expansion. Do not use them.
2821 Do not use tab characters. Their effect is not predictable.
2825 See <ref id="descriptions"> for further information on this.
2829 In a <file>.changes</file> file, the <tt>Description</tt> field
2830 contains a summary of the descriptions for the packages being
2835 The part of the field before the first newline is empty;
2836 thereafter each line has the name of a binary package and
2837 the summary description line from that binary package.
2838 Each line is indented by one space.
2843 <sect1 id="f-Distribution">
2844 <heading><tt>Distribution</tt></heading>
2847 In a <file>.changes</file> file or parsed changelog output
2848 this contains the (space-separated) name(s) of the
2849 distribution(s) where this version of the package should
2850 be installed. Valid distributions are determined by the
2851 archive maintainers.<footnote>
2852 Current distribution names are:
2853 <taglist compact="compact">
2854 <tag><em>stable</em></tag>
2856 This is the current "released" version of Debian
2857 GNU/Linux. Once the distribution is
2858 <em>stable</em> only security fixes and other
2859 major bug fixes are allowed. When changes are
2860 made to this distribution, the release number is
2861 increased (for example: 2.2r1 becomes 2.2r2 then
2865 <tag><em>unstable</em></tag>
2867 This distribution value refers to the
2868 <em>developmental</em> part of the Debian
2869 distribution tree. New packages, new upstream
2870 versions of packages and bug fixes go into the
2871 <em>unstable</em> directory tree. Download from
2872 this distribution at your own risk.
2875 <tag><em>testing</em></tag>
2877 This distribution value refers to the
2878 <em>testing</em> part of the Debian distribution
2879 tree. It receives its packages from the
2880 unstable distribution after a short time lag to
2881 ensure that there are no major issues with the
2882 unstable packages. It is less prone to breakage
2883 than unstable, but still risky. It is not
2884 possible to upload packages directly to
2888 <tag><em>frozen</em></tag>
2890 From time to time, the <em>testing</em>
2891 distribution enters a state of "code-freeze" in
2892 anticipation of release as a <em>stable</em>
2893 version. During this period of testing only
2894 fixes for existing or newly-discovered bugs will
2895 be allowed. The exact details of this stage are
2896 determined by the Release Manager.
2899 <tag><em>experimental</em></tag>
2901 The packages with this distribution value are
2902 deemed by their maintainers to be high
2903 risk. Oftentimes they represent early beta or
2904 developmental packages from various sources that
2905 the maintainers want people to try, but are not
2906 ready to be a part of the other parts of the
2907 Debian distribution tree. Download at your own
2913 You should list <em>all</em> distributions that the
2914 package should be installed into.
2918 More information is available in the Debian Developer's
2919 Reference, section "The Debian archive".
2926 <heading><tt>Date</tt></heading>
2929 This field includes the date the package was built or last edited.
2933 The value of this field is usually extracted from the
2934 <file>debian/changelog</file> file - see
2935 <ref id="dpkgchangelog">).
2939 <sect1 id="f-Format">
2940 <heading><tt>Format</tt></heading>
2943 This field specifies a format revision for the file.
2944 The most current format described in the Policy Manual
2945 is version <strong>1.5</strong>. The syntax of the
2946 format value is the same as that of a package version
2947 number except that no epoch or Debian revision is allowed
2948 - see <ref id="f-Version">.
2952 <sect1 id="f-Urgency">
2953 <heading><tt>Urgency</tt></heading>
2956 This is a description of how important it is to upgrade to
2957 this version from previous ones. It consists of a single
2958 keyword usually taking one of the values <tt>low</tt>,
2959 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2960 followed by an optional commentary (separated by a space)
2961 which is usually in parentheses. For example:
2964 Urgency: low (HIGH for users of diversions)
2970 The value of this field is usually extracted from the
2971 <file>debian/changelog</file> file - see
2972 <ref id="dpkgchangelog">.
2976 <sect1 id="f-Changes">
2977 <heading><tt>Changes</tt></heading>
2980 This field contains the human-readable changes data, describing
2981 the differences between the last version and the current one.
2985 There should be nothing in this field before the first
2986 newline; all the subsequent lines must be indented by at
2987 least one space; blank lines must be represented by a line
2988 consiting only of a space and a full stop.
2992 The value of this field is usually extracted from the
2993 <file>debian/changelog</file> file - see
2994 <ref id="dpkgchangelog">).
2998 Each version's change information should be preceded by a
2999 "title" line giving at least the version, distribution(s)
3000 and urgency, in a human-readable way.
3004 If data from several versions is being returned the entry
3005 for the most recent version should be returned first, and
3006 entries should be separated by the representation of a
3007 blank line (the "title" line may also be followed by the
3008 representation of blank line).
3012 <sect1 id="f-Binary">
3013 <heading><tt>Binary</tt></heading>
3016 This field is a list of binary packages.
3020 When it appears in the <file>.dsc</file> file it is the list
3021 of binary packages which a source package can produce. It
3022 does not necessarily produce all of these binary packages
3023 for every architecture. The source control file doesn't
3024 contain details of which architectures are appropriate for
3025 which of the binary packages.
3029 When it appears in a <file>.changes</file> file it lists the
3030 names of the binary packages actually being uploaded.
3034 The syntax is a list of binary packages separated by
3036 A space after each comma is conventional.
3037 </footnote>. Currently the packages must be separated using
3038 only spaces in the <file>.changes</file> file.
3042 <sect1 id="f-Installed-Size">
3043 <heading><tt>Installed-Size</tt></heading>
3046 This field appears in the control files of binary
3047 packages, and in the <file>Packages</file> files. It gives
3048 the total amount of disk space required to install the
3053 The disk space is represented in kilobytes as a simple
3058 <sect1 id="f-Files">
3059 <heading><tt>Files</tt></heading>
3062 This field contains a list of files with information about
3063 each one. The exact information and syntax varies with
3064 the context. In all cases the part of the field
3065 contents on the same line as the field name is empty. The
3066 remainder of the field is one line per file, each line
3067 being indented by one space and containing a number of
3068 sub-fields separated by spaces.
3072 In the <file>.dsc</file> file, each line contains the MD5
3073 checksum, size and filename of the tar file and (if applicable)
3074 diff file which make up the remainder of the source
3076 That is, the parts which are not the <tt>.dsc</tt>.
3078 The exact forms of the filenames are described
3079 in <ref id="pkg-sourcearchives">.
3083 In the <file>.changes</file> file this contains one line per
3084 file being uploaded. Each line contains the MD5 checksum,
3085 size, section and priority and the filename.
3086 The <qref id="f-Section">section</qref>
3087 and <qref id="f-Priority">priority</qref>
3088 are the values of the corresponding fields in
3089 the main source control file. If no section or priority is
3090 specified then <tt>-</tt> should be used, though section
3091 and priority values must be specified for new packages to
3092 be installed properly.
3096 The special value <tt>byhand</tt> for the section in a
3097 <tt>.changes</tt> file indicates that the file in question
3098 is not an ordinary package file and must by installed by
3099 hand by the distribution maintainers. If the section is
3100 <tt>byhand</tt> the priority should be <tt>-</tt>.
3104 If a new Debian revision of a package is being shipped and
3105 no new original source archive is being distributed the
3106 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3107 entry for the original source archive
3108 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3109 but the <file>.changes</file> file should leave it out. In
3110 this case the original source archive on the distribution
3111 site must match exactly, byte-for-byte, the original
3112 source archive which was used to generate the
3113 <file>.dsc</file> file and diff which are being uploaded.</p>
3116 <sect1 id="f-Closes">
3117 <heading><tt>Closes</tt></heading>
3120 A space-separated list of bug report numbers that the upload
3121 governed by the .changes file closes.
3128 <heading>User-defined fields</heading>
3131 Additional user-defined fields may be added to the
3132 source package control file. Such fields will be
3133 ignored, and not copied to (for example) binary or
3134 source package control files or upload control files.
3138 If you wish to add additional unsupported fields to
3139 these output files you should use the mechanism
3144 Fields in the main source control information file with
3145 names starting <tt>X</tt>, followed by one or more of
3146 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3147 be copied to the output files. Only the part of the
3148 field name after the hyphen will be used in the output
3149 file. Where the letter <tt>B</tt> is used the field
3150 will appear in binary package control files, where the
3151 letter <tt>S</tt> is used in source package control
3152 files and where <tt>C</tt> is used in upload control
3153 (<tt>.changes</tt>) files.
3157 For example, if the main source information control file
3160 XBS-Comment: I stand between the candle and the star.
3162 then the binary and source package control files will contain the
3165 Comment: I stand between the candle and the star.
3174 <chapt id="maintainerscripts">
3175 <heading>Package maintainer scripts and installation procedure</heading>
3178 <heading>Introduction to package maintainer scripts</heading>
3181 It is possible to supply scripts as part of a package which
3182 the package management system will run for you when your
3183 package is installed, upgraded or removed.
3187 These scripts are the files <prgn>preinst</prgn>,
3188 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3189 control area of the package. They must be proper executable
3190 files; if they are scripts (which is recommended), they must
3191 start with the usual <tt>#!</tt> convention. They should be
3192 readable and executable by anyone, and not world-writable.
3196 The package management system looks at the exit status from
3197 these scripts. It is important that they exit with a
3198 non-zero status if there is an error, so that the package
3199 management system can stop its processing. For shell
3200 scripts this means that you <em>almost always</em> need to
3201 use <tt>set -e</tt> (this is usually true when writing shell
3202 scripts, in fact). It is also important, of course, that
3203 they don't exit with a non-zero status if everything went
3208 When a package is upgraded a combination of the scripts from
3209 the old and new packages is called during the upgrade
3210 procedure. If your scripts are going to be at all
3211 complicated you need to be aware of this, and may need to
3212 check the arguments to your scripts.
3216 Broadly speaking the <prgn>preinst</prgn> is called before
3217 (a particular version of) a package is installed, and the
3218 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3219 before (a version of) a package is removed and the
3220 <prgn>postrm</prgn> afterwards.
3224 Programs called from maintainer scripts should not normally
3225 have a path prepended to them. Before installation is
3226 started, the package management system checks to see if the
3227 programs <prgn>ldconfig</prgn>,
3228 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3229 and <prgn>update-rc.d</prgn> can be found via the
3230 <tt>PATH</tt> environment variable. Those programs, and any
3231 other program that one would expect to be on the
3232 <tt>PATH</tt>, should thus be invoked without an absolute
3233 pathname. Maintainer scripts should also not reset the
3234 <tt>PATH</tt>, though they might choose to modify it by
3235 prepending or appending package-specific directories. These
3236 considerations really apply to all shell scripts.</p>
3239 <sect id="idempotency">
3240 <heading>Maintainer scripts Idempotency</heading>
3243 It is necessary for the error recovery procedures that the
3244 scripts be idempotent. This means that if it is run
3245 successfully, and then it is called again, it doesn't bomb
3246 out or cause any harm, but just ensures that everything is
3247 the way it ought to be. If the first call failed, or
3248 aborted half way through for some reason, the second call
3249 should merely do the things that were left undone the first
3250 time, if any, and exit with a success status if everything
3252 This is so that if an error occurs, the user interrupts
3253 <prgn>dpkg</prgn> or some other unforeseen circumstance
3254 happens you don't leave the user with a badly-broken
3255 package when <prgn>dpkg</prgn> attempts to repeat the
3261 <sect id="controllingterminal">
3262 <heading>Controlling terminal for maintainer scripts</heading>
3265 The maintainer scripts are guaranteed to run with a
3266 controlling terminal and can interact with the user.
3267 If they need to prompt for passwords, do full-screen
3268 interaction or something similar you should do these
3269 things to and from <file>/dev/tty</file>, since
3270 <prgn>dpkg</prgn> will at some point redirect scripts'
3271 standard input and output so that it can log the
3272 installation process. Likewise, because these scripts
3273 may be executed with standard output redirected into a
3274 pipe for logging purposes, Perl scripts should set
3275 unbuffered output by setting <tt>$|=1</tt> so that the
3276 output is printed immediately rather than being
3281 Each script should return a zero exit status for
3282 success, or a nonzero one for failure.
3286 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3291 <list compact="compact">
3293 <var>new-preinst</var> <tt>install</tt>
3296 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3299 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3302 <var>old-preinst</var> <tt>abort-upgrade</tt>
3303 <var>new-version</var>
3308 <list compact="compact">
3310 <var>postinst</var> <tt>configure</tt>
3311 <var>most-recently-configured-version</var>
3314 <var>old-postinst</var> <tt>abort-upgrade</tt>
3315 <var>new-version</var>
3318 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3319 <tt>in-favour</tt> <var>package</var>
3320 <var>new-version</var>
3323 <var>deconfigured's-postinst</var>
3324 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3325 <var>failed-install-package</var> <var>version</var>
3326 <tt>removing</tt> <var>conflicting-package</var>
3332 <list compact="compact">
3334 <var>prerm</var> <tt>remove</tt>
3337 <var>old-prerm</var> <tt>upgrade</tt>
3338 <var>new-version</var>
3341 <var>new-prerm</var> <tt>failed-upgrade</tt>
3342 <var>old-version</var>
3345 <var>conflictor's-prerm</var> <tt>remove</tt>
3346 <tt>in-favour</tt> <var>package</var>
3347 <var>new-version</var>
3350 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3351 <tt>in-favour</tt> <var>package-being-installed</var>
3352 <var>version</var> <tt>removing</tt>
3353 <var>conflicting-package</var>
3359 <list compact="compact">
3361 <var>postrm</var> <tt>remove</tt>
3364 <var>postrm</var> <tt>purge</tt>
3367 <var>old-postrm</var> <tt>upgrade</tt>
3368 <var>new-version</var>
3371 <var>new-postrm</var> <tt>failed-upgrade</tt>
3372 <var>old-version</var>
3375 <var>new-postrm</var> <tt>abort-install</tt>
3378 <var>new-postrm</var> <tt>abort-install</tt>
3379 <var>old-version</var>
3382 <var>new-postrm</var> <tt>abort-upgrade</tt>
3383 <var>old-version</var>
3386 <var>disappearer's-postrm</var> <tt>disappear</tt>
3387 <var>overwriter</var>
3388 <var>overwriter-version</var>
3394 <sect id="unpackphase">
3395 <heading>Details of unpack phase of installation or upgrade</heading>
3398 The procedure on installation/upgrade/overwrite/disappear
3399 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3400 stage of <tt>dpkg --install</tt>) is as follows. In each
3401 case, if a major error occurs (unless listed below) the
3402 actions are, in general, run backwards - this means that the
3403 maintainer scripts are run with different arguments in
3404 reverse order. These are the "error unwind" calls listed
3411 If a version of the package is already installed, call
3412 <example compact="compact">
3413 <var>old-prerm</var> upgrade <var>new-version</var>
3417 If the script runs but exits with a non-zero
3418 exit status, <prgn>dpkg</prgn> will attempt:
3419 <example compact="compact">
3420 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3422 Error unwind, for both the above cases:
3423 <example compact="compact">
3424 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3431 If a "conflicting" package is being removed at the same time:
3434 If any packages depended on that conflicting
3435 package and <tt>--auto-deconfigure</tt> is
3436 specified, call, for each such package:
3437 <example compact="compact">
3438 <var>deconfigured's-prerm</var> deconfigure \
3439 in-favour <var>package-being-installed</var> <var>version</var> \
3440 removing <var>conflicting-package</var> <var>version</var>
3443 <example compact="compact">
3444 <var>deconfigured's-postinst</var> abort-deconfigure \
3445 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3446 removing <var>conflicting-package</var> <var>version</var>
3448 The deconfigured packages are marked as
3449 requiring configuration, so that if
3450 <tt>--install</tt> is used they will be
3451 configured again if possible.
3454 To prepare for removal of the conflicting package, call:
3455 <example compact="compact">
3456 <var>conflictor's-prerm</var> remove \
3457 in-favour <var>package</var> <var>new-version</var>
3460 <example compact="compact">
3461 <var>conflictor's-postinst</var> abort-remove \
3462 in-favour <var>package</var> <var>new-version</var>
3471 If the package is being upgraded, call:
3472 <example compact="compact">
3473 <var>new-preinst</var> upgrade <var>old-version</var>
3477 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3479 If that too fails, then
3481 <var>old-postinst</var> abort-upgrade <var>old-version</var>
3486 Otherwise, if the package had some configuration
3487 files from a previous version installed (i.e., it
3488 is in the "configuration files only" state):
3489 <example compact="compact">
3490 <var>new-preinst</var> install <var>old-version</var>
3494 <var>new-postrm</var> abort-install <var>old-version</var>
3498 Otherwise (i.e., the package was completely purged):
3499 <example compact="compact">
3500 <var>new-preinst</var> install
3503 <example compact="compact">
3504 <var>new-postrm</var> abort-install
3512 The new package's files are unpacked, overwriting any
3513 that may be on the system already, for example any
3514 from the old version of the same package or from
3515 another package. Backups of the old files are kept
3516 temporarily, and if anything goes wrong the package
3517 management system will attempt to put them back as
3518 part of the error unwind.
3522 It is an error for a package to contain files which
3523 are on the system in another package, unless
3524 <tt>Replaces</tt> is used (see <ref id="replaces">).
3526 The following paragraph is not currently the case:
3527 Currently the <tt>- - force-overwrite</tt> flag is
3528 enabled, downgrading it to a warning, but this may not
3534 It is a more serious error for a package to contain a
3535 plain file or other kind of non-directory where another
3536 package has a directory (again, unless
3537 <tt>Replaces</tt> is used). This error can be
3538 overridden if desired using
3539 <tt>--force-overwrite-dir</tt>, but this is not
3544 Packages which overwrite each other's files produce
3545 behavior which, though deterministic, is hard for the
3546 system administrator to understand. It can easily
3547 lead to "missing" programs if, for example, a package
3548 is installed which overwrites a file from another
3549 package, and is then removed again.<footnote>
3550 Part of the problem is due to what is arguably a
3551 bug in <prgn>dpkg</prgn>.
3556 A directory will never be replaced by a symbolic link
3557 to a directory or vice versa; instead, the existing
3558 state (symlink or not) will be left alone and
3559 <prgn>dpkg</prgn> will follow the symlink if there is
3568 If the package is being upgraded, call
3569 <example compact="compact">
3570 <var>old-postrm</var> upgrade <var>new-version</var>
3574 If this fails, <prgn>dpkg</prgn> will attempt:
3575 <example compact="compact">
3576 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3578 Error unwind, for both cases:
3579 <example compact="compact">
3580 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3587 This is the point of no return - if
3588 <prgn>dpkg</prgn> gets this far, it won't back off
3589 past this point if an error occurs. This will
3590 leave the package in a fairly bad state, which
3591 will require a successful re-installation to clear
3592 up, but it's when <prgn>dpkg</prgn> starts doing
3593 things that are irreversible.
3598 Any files which were in the old version of the package
3599 but not in the new are removed.
3603 The new file list replaces the old.
3607 The new maintainer scripts replace the old.
3611 Any packages all of whose files have been overwritten
3612 during the installation, and which aren't required for
3613 dependencies, are considered to have been removed.
3614 For each such package
3617 <prgn>dpkg</prgn> calls:
3618 <example compact="compact">
3619 <var>disappearer's-postrm</var> disappear \
3620 <var>overwriter</var> <var>overwriter-version</var>
3624 The package's maintainer scripts are removed.
3627 It is noted in the status database as being in a
3628 sane state, namely not installed (any conffiles
3629 it may have are ignored, rather than being
3630 removed by <prgn>dpkg</prgn>). Note that
3631 disappearing packages do not have their prerm
3632 called, because <prgn>dpkg</prgn> doesn't know
3633 in advance that the package is going to
3640 Any files in the package we're unpacking that are also
3641 listed in the file lists of other packages are removed
3642 from those lists. (This will lobotomize the file list
3643 of the "conflicting" package if there is one.)
3647 The backup files made during installation, above, are
3653 The new package's status is now sane, and recorded as
3658 Here is another point of no return - if the
3659 conflicting package's removal fails we do not unwind
3660 the rest of the installation; the conflicting package
3661 is left in a half-removed limbo.
3666 If there was a conflicting package we go and do the
3667 removal actions (described below), starting with the
3668 removal of the conflicting package's files (any that
3669 are also in the package being installed have already
3670 been removed from the conflicting package's file list,
3671 and so do not get removed now).
3677 <sect id="configdetails"><heading>Details of configuration</heading>
3680 When we configure a package (this happens with <tt>dpkg
3681 --install</tt> and <tt>dpkg --configure</tt>), we first
3682 update any <tt>conffile</tt>s and then call:
3683 <example compact="compact">
3684 <var>postinst</var> configure <var>most-recently-configured-version</var>
3689 No attempt is made to unwind after errors during
3694 If there is no most recently configured version
3695 <prgn>dpkg</prgn> will pass a null argument.
3698 Historical note: Truly ancient (pre-1997) versions of
3699 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3700 (including the angle brackets) in this case. Even older
3701 ones did not pass a second argument at all, under any
3702 circumstance. Note that upgrades using such an old dpkg
3703 version are unlikely to work for other reasons, even if
3704 this old argument behavior is handled by your postinst script.
3710 <sect id="removedetails"><heading>Details of removal and/or
3711 configuration purging</heading>
3716 <example compact="compact">
3717 <var>prerm</var> remove
3721 The package's files are removed (except <tt>conffile</tt>s).
3724 <example compact="compact">
3725 <var>postrm</var> remove
3730 All the maintainer scripts except the <prgn>postrm</prgn>
3735 If we aren't purging the package we stop here. Note
3736 that packages which have no <prgn>postrm</prgn> and no
3737 <tt>conffile</tt>s are automatically purged when
3738 removed, as there is no difference except for the
3739 <prgn>dpkg</prgn> status.
3743 The <tt>conffile</tt>s and any backup files
3744 (<tt>~</tt>-files, <tt>#*#</tt> files,
3745 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3749 <example compact="compact">
3750 <var>postrm</var> purge
3754 The package's file list is removed.
3758 If there are problems during this process, we call
3759 <example compact="compact">postinst
3760 abort-remove</example>. No other attempt is made to unwind
3761 after errors during removal.
3767 <chapt id="relationships">
3768 <heading>Declaring relationships between packages</heading>
3770 <sect id="depsyntax">
3771 <heading>Syntax of relationship fields</heading>
3774 These fields all have a uniform syntax. They are a list of
3775 package names separated by commas.
3779 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3780 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3781 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3782 control file fields of the package, which declare
3783 dependencies on other packages, the package names listed may
3784 also include lists of alternative package names, separated
3785 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3786 if any one of the alternative packages is installed, that
3787 part of the dependency is considered to be satisfied.
3791 All of the fields except for <tt>Provides</tt> may restrict
3792 their applicability to particular versions of each named
3793 package. This is done in parentheses after each individual
3794 package name; the parentheses should contain a relation from
3795 the list below followed by a version number, in the format
3796 described in <ref id="f-Version">.
3800 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3801 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3802 strictly earlier, earlier or equal, exactly equal, later or
3803 equal and strictly later, respectively. The deprecated
3804 forms <tt><</tt> and <tt>></tt> were used to mean
3805 earlier/later or equal, rather than strictly earlier/later,
3806 so they should not appear in new packages (though
3807 <prgn>dpkg</prgn> still supports them).
3811 Whitespace may appear at any point in the version
3812 specification subject to the rules in <ref
3813 id="controlsyntax">, and must appear where it's necessary to
3814 disambiguate; it is not otherwise significant. For
3815 consistency and in case of future changes to
3816 <prgn>dpkg</prgn> it is recommended that a single space be
3817 used after a version relationship and before a version
3818 number; it is also conventional to put a single space after
3819 each comma, on either side of each vertical bar, and before
3820 each open parenthesis.
3824 For example, a list of dependencies might appear as:
3825 <example compact="compact">
3828 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3833 All fields that specify build-time relationships
3834 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3835 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3836 may be restricted to a certain set of architectures. This
3837 is indicated in brackets after each individual package name and
3838 the optional version specification. The brackets enclose a
3839 list of Debian architecture names separated by whitespace.
3840 Exclamation marks may be prepended to each of the names.
3841 (It is not permitted for some names to be prepended with
3842 exclamation marks and others not.) If the current Debian
3843 host architecture is not in this list and there are no
3844 exclamation marks in the list, or it is in the list with a
3845 prepended exclamation mark, the package name and the
3846 associated version specification are ignored completely for
3847 the purposes of defining the relationships.
3852 <example compact="compact">
3854 Build-Depends-Indep: texinfo
3855 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3856 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3861 Note that the binary package relationship fields such as
3862 <tt>Depends</tt> appear in one of the binary package
3863 sections of the control file, whereas the build-time
3864 relationships such as <tt>Build-Depends</tt> appear in the
3865 source package section of the control file (which is the
3870 <sect id="binarydeps">
3871 <heading>Binary Dependencies - <tt>Depends</tt>,
3872 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3873 <tt>Pre-Depends</tt>
3877 Packages can declare in their control file that they have
3878 certain relationships to other packages - for example, that
3879 they may not be installed at the same time as certain other
3880 packages, and/or that they depend on the presence of others.
3884 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3885 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3886 <tt>Conflicts</tt> control file fields.
3890 These six fields are used to declare a dependency
3891 relationship by one package on another. Except for
3892 <tt>Enhances</tt>, they appear in the depending (binary)
3893 package's control file. (<tt>Enhances</tt> appears in the
3894 recommending package's control file.)
3898 A <tt>Depends</tt> field takes effect <em>only</em> when a
3899 package is to be configured. It does not prevent a package
3900 being on the system in an unconfigured state while its
3901 dependencies are unsatisfied, and it is possible to replace
3902 a package whose dependencies are satisfied and which is
3903 properly installed with a different version whose
3904 dependencies are not and cannot be satisfied; when this is
3905 done the depending package will be left unconfigured (since
3906 attempts to configure it will give errors) and will not
3907 function properly. If it is necessary, a
3908 <tt>Pre-Depends</tt> field can be used, which has a partial
3909 effect even when a package is being unpacked, as explained
3910 in detail below. (The other three dependency fields,
3911 <tt>Recommends</tt>, <tt>Suggests</tt> and
3912 <tt>Enhances</tt>, are only used by the various front-ends
3913 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3917 For this reason packages in an installation run are usually
3918 all unpacked first and all configured later; this gives
3919 later versions of packages with dependencies on later
3920 versions of other packages the opportunity to have their
3921 dependencies satisfied.
3925 The <tt>Depends</tt> field thus allows package maintainers
3926 to impose an order in which packages should be configured.
3930 The meaning of the five dependency fields is as follows:
3932 <tag><tt>Depends</tt></tag>
3935 This declares an absolute dependency. A package will
3936 not be configured unless all of the packages listed in
3937 its <tt>Depends</tt> field have been correctly
3942 The <tt>Depends</tt> field should be used if the
3943 depended-on package is required for the depending
3944 package to provide a significant amount of
3949 The <tt>Depends</tt> field should also be used if the
3950 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3951 <prgn>postrm</prgn> scripts require the package to be
3952 present in order to run. Note, however, that the
3953 <prgn>postrm</prgn> cannot rely on any non-essential
3954 packages to be present during the <tt>purge</tt>
3958 <tag><tt>Recommends</tt></tag>
3961 This declares a strong, but not absolute, dependency.
3965 The <tt>Recommends</tt> field should list packages
3966 that would be found together with this one in all but
3967 unusual installations.
3971 <tag><tt>Suggests</tt></tag>
3973 This is used to declare that one package may be more
3974 useful with one or more others. Using this field
3975 tells the packaging system and the user that the
3976 listed packages are related to this one and can
3977 perhaps enhance its usefulness, but that installing
3978 this one without them is perfectly reasonable.
3981 <tag><tt>Enhances</tt></tag>
3983 This field is similar to Suggests but works in the
3984 opposite direction. It is used to declare that a
3985 package can enhance the functionality of another
3989 <tag><tt>Pre-Depends</tt></tag>
3992 This field is like <tt>Depends</tt>, except that it
3993 also forces <prgn>dpkg</prgn> to complete installation
3994 of the packages named before even starting the
3995 installation of the package which declares the
3996 pre-dependency, as follows:
4000 When a package declaring a pre-dependency is about to
4001 be <em>unpacked</em> the pre-dependency can be
4002 satisfied if the depended-on package is either fully
4003 configured, <em>or even if</em> the depended-on
4004 package(s) are only unpacked or half-configured,
4005 provided that they have been configured correctly at
4006 some point in the past (and not removed or partially
4007 removed since). In this case, both the
4008 previously-configured and currently unpacked or
4009 half-configured versions must satisfy any version
4010 clause in the <tt>Pre-Depends</tt> field.
4014 When the package declaring a pre-dependency is about
4015 to be <em>configured</em>, the pre-dependency will be
4016 treated as a normal <tt>Depends</tt>, that is, it will
4017 be considered satisfied only if the depended-on
4018 package has been correctly configured.
4022 <tt>Pre-Depends</tt> should be used sparingly,
4023 preferably only by packages whose premature upgrade or
4024 installation would hamper the ability of the system to
4025 continue with any upgrade that might be in progress.
4029 <tt>Pre-Depends</tt> are also required if the
4030 <prgn>preinst</prgn> script depends on the named
4031 package. It is best to avoid this situation if
4039 When selecting which level of dependency to use you should
4040 consider how important the depended-on package is to the
4041 functionality of the one declaring the dependency. Some
4042 packages are composed of components of varying degrees of
4043 importance. Such a package should list using
4044 <tt>Depends</tt> the package(s) which are required by the
4045 more important components. The other components'
4046 requirements may be mentioned as Suggestions or
4047 Recommendations, as appropriate to the components' relative
4052 <sect id="conflicts">
4053 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4056 When one binary package declares a conflict with another
4057 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4058 refuse to allow them to be installed on the system at the
4063 If one package is to be installed, the other must be removed
4064 first - if the package being installed is marked as
4065 replacing (see <ref id="replaces">) the one on the system,
4066 or the one on the system is marked as deselected, or both
4067 packages are marked <tt>Essential</tt>, then
4068 <prgn>dpkg</prgn> will automatically remove the package
4069 which is causing the conflict, otherwise it will halt the
4070 installation of the new package with an error. This
4071 mechanism is specifically designed to produce an error when
4072 the installed package is <tt>Essential</tt>, but the new
4077 A package will not cause a conflict merely because its
4078 configuration files are still installed; it must be at least
4083 A special exception is made for packages which declare a
4084 conflict with their own package name, or with a virtual
4085 package which they provide (see below): this does not
4086 prevent their installation, and allows a package to conflict
4087 with others providing a replacement for it. You use this
4088 feature when you want the package in question to be the only
4089 package providing some feature.
4093 A <tt>Conflicts</tt> entry should almost never have an
4094 "earlier than" version clause. This would prevent
4095 <prgn>dpkg</prgn> from upgrading or installing the package
4096 which declared such a conflict until the upgrade or removal
4097 of the conflicted-with package had been completed.
4101 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4105 As well as the names of actual ("concrete") packages, the
4106 package relationship fields <tt>Depends</tt>,
4107 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4108 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4109 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4110 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4111 may mention "virtual packages".
4115 A <em>virtual package</em> is one which appears in the
4116 <tt>Provides</tt> control file field of another package.
4117 The effect is as if the package(s) which provide a
4118 particular virtual package name had been listed by name
4119 everywhere the virtual package name appears. (See also <ref
4124 If there are both concrete and virtual packages of the same
4125 name, then the dependency may be satisfied (or the conflict
4126 caused) by either the concrete package with the name in
4127 question or any other concrete package which provides the
4128 virtual package with the name in question. This is so that,
4129 for example, supposing we have
4130 <example compact="compact">
4134 and someone else releases an enhanced version of the
4135 <tt>bar</tt> package (for example, a non-US variant), they
4137 <example compact="compact">
4141 and the <tt>bar-plus</tt> package will now also satisfy the
4142 dependency for the <tt>foo</tt> package.
4146 If a dependency or a conflict has a version number attached
4147 then only real packages will be considered to see whether
4148 the relationship is satisfied (or the prohibition violated,
4149 for a conflict) - it is assumed that a real package which
4150 provides the virtual package is not of the "right" version.
4151 So, a <tt>Provides</tt> field may not contain version
4152 numbers, and the version number of the concrete package
4153 which provides a particular virtual package will not be
4154 looked at when considering a dependency on or conflict with
4155 the virtual package name.
4159 It is likely that the ability will be added in a future
4160 release of <prgn>dpkg</prgn> to specify a version number for
4161 each virtual package it provides. This feature is not yet
4162 present, however, and is expected to be used only
4167 If you want to specify which of a set of real packages
4168 should be the default to satisfy a particular dependency on
4169 a virtual package, you should list the real package as an
4170 alternative before the virtual one.
4175 <sect id="replaces"><heading>Overwriting files and replacing
4176 packages - <tt>Replaces</tt></heading>
4179 Packages can declare in their control file that they should
4180 overwrite files in certain other packages, or completely
4181 replace other packages. The <tt>Replaces</tt> control file
4182 field has these two distinct purposes.
4185 <sect1><heading>Overwriting files in other packages</heading>
4188 Firstly, as mentioned before, it is usually an error for a
4189 package to contain files which are on the system in
4194 However, if the overwriting package declares that it
4195 <tt>Replaces</tt> the one containing the file being
4196 overwritten, then <prgn>dpkg</prgn> will replace the file
4197 from the old package with that from the new. The file
4198 will no longer be listed as "owned" by the old package.
4202 If a package is completely replaced in this way, so that
4203 <prgn>dpkg</prgn> does not know of any files it still
4204 contains, it is considered to have "disappeared". It will
4205 be marked as not wanted on the system (selected for
4206 removal) and not installed. Any <tt>conffile</tt>s
4207 details noted for the package will be ignored, as they
4208 will have been taken over by the overwriting package. The
4209 package's <prgn>postrm</prgn> script will be run with a
4210 special argument to allow the package to do any final
4211 cleanup required. See <ref id="mscriptsinstact">.
4214 Replaces is a one way relationship -- you have to
4215 install the replacing package after the replaced
4222 For this usage of <tt>Replaces</tt>, virtual packages (see
4223 <ref id="virtual">) are not considered when looking at a
4224 <tt>Replaces</tt> field - the packages declared as being
4225 replaced must be mentioned by their real names.
4229 Furthermore, this usage of <tt>Replaces</tt> only takes
4230 effect when both packages are at least partially on the
4231 system at once, so that it can only happen if they do not
4232 conflict or if the conflict has been overridden.
4237 <sect1><heading>Replacing whole packages, forcing their
4241 Secondly, <tt>Replaces</tt> allows the packaging system to
4242 resolve which package should be removed when there is a
4243 conflict - see <ref id="conflicts">. This usage only
4244 takes effect when the two packages <em>do</em> conflict,
4245 so that the two usages of this field do not interfere with
4250 In this situation, the package declared as being replaced
4251 can be a virtual package, so for example, all mail
4252 transport agents (MTAs) would have the following fields in
4253 their control files:
4254 <example compact="compact">
4255 Provides: mail-transport-agent
4256 Conflicts: mail-transport-agent
4257 Replaces: mail-transport-agent
4259 ensuring that only one MTA can be installed at any one
4264 <sect id="sourcebinarydeps">
4265 <heading>Relationships between source and binary packages -
4266 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4267 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4271 Source packages that require certain binary packages to be
4272 installed or absent at the time of building the package
4273 can declare relationships to those binary packages.
4277 This is done using the <tt>Build-Depends</tt>,
4278 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4279 <tt>Build-Conflicts-Indep</tt> control file fields.
4283 Build-dependencies on "build-essential" binary packages can be
4284 omitted. Please see <ref id="pkg-relations"> for more information.
4288 The dependencies and conflicts they define must be satisfied
4289 (as defined earlier for binary packages) in order to invoke
4290 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4292 If you make "build-arch" or "binary-arch", you need
4293 Build-Depends. If you make "build-indep" or
4294 "binary-indep", you need Build-Depends and
4295 Build-Depends-Indep. If you make "build" or "binary",
4299 There is no Build-Depends-Arch; the autobuilders will
4300 only need the Build-Depends if they know how to build
4301 only build-arch and binary-arch. Anyone building the
4302 build-indep/binary-indep targets is basically assumed to
4303 be building the whole package and so installs all build
4307 The purpose of the original split, I recall, was so that
4308 the autobuilders wouldn't need to install extra packages
4309 needed only for the binary-indep targets. But without a
4310 build-arch/build-indep split, this didn't work, since
4311 most of the work is done in the build target, not in the
4317 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4319 The <tt>Build-Depends</tt> and
4320 <tt>Build-Conflicts</tt> fields must be satisfied when
4321 any of the following targets is invoked:
4322 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4323 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4324 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4326 <tag><tt>Build-Depends-Indep</tt>,
4327 <tt>Build-Conflicts-Indep</tt></tag>
4329 The <tt>Build-Depends-Indep</tt> and
4330 <tt>Build-Conflicts-Indep</tt> fields must be
4331 satisfied when any of the following targets is
4332 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4333 <tt>binary</tt> and <tt>binary-indep</tt>.
4343 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4346 Packages containing shared libraries must be constructed with
4347 a little care to make sure that the shared library is always
4348 available. This is especially important for packages whose
4349 shared libraries are vitally important, such as the C library
4350 (currently <tt>libc6</tt>).
4354 Packages involving shared libraries should be split up into
4355 several binary packages. This section mostly deals with how
4356 this separation is to be accomplished; rules for files within
4357 the shared library packages are in <ref id="libraries"> instead.
4360 <sect id="sharedlibs-runtime">
4361 <heading>Run-time shared libraries</heading>
4364 The run-time shared library needs to be placed in a package
4365 whose name changes whenever the shared object version
4368 Since it is common place to install several versions of a
4369 package that just provides shared libraries, it is a
4370 good idea that that the library package should not
4371 contain any extraneous non-versioned files, unless they
4372 happen to be in versioned directories.</p>
4374 The most common mechanism is to place it in a package
4376 <package><var>libraryname</var><var>soversion</var></package>,
4377 where <file><var>soversion</var></file> is the version number
4378 in the soname of the shared library<footnote>
4379 The soname is the shared object name: it's the thing
4380 that has to match exactly between building an executable
4381 and running it for the dynamic linker to be able run the
4382 program. For example, if the soname of the library is
4383 <file>libfoo.so.6</file>, the library package would be
4384 called <file>libfoo6</file>.
4386 Alternatively, if it would be confusing to directly append
4387 <var>soversion</var> to <var>libraryname</var> (e.g. because
4388 <var>libraryname</var> itself ends in a number), you may use
4389 <package><var>libraryname</var>-<var>soversion</var></package> and
4390 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4394 If you have several shared libraries built from the same
4395 source tree you may lump them all together into a single
4396 shared library package, provided that you change all of
4397 their sonames at once (so that you don't get filename
4398 clashes if you try to install different versions of the
4399 combined shared libraries package).
4403 The package should install the shared libraries under
4404 their normal names. For example, the <package>libgdbm3</package>
4405 package should install <file>libgdbm.so.3.0.0</file> as
4406 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4407 renamed or re-linked by any <prgn>prerm</prgn> or
4408 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4409 of renaming things safely without affecting running programs,
4410 and attempts to interfere with this are likely to lead to
4415 Shared libraries should not be installed executable, since
4416 the dynamic linker does not require this and trying to
4417 execute a shared library usually results in a core dump.
4421 The run-time library package should include the symbolic link that
4422 <prgn>ldconfig</prgn> would create for the shared libraries.
4423 For example, the <package>libgdbm3</package> package should include
4424 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4425 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4426 linker (for example <prgn>ld.so</prgn> or
4427 <prgn>ld-linux.so.*</prgn>) can find the library between the
4428 time that <prgn>dpkg</prgn> installs it and the time that
4429 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4431 The package management system requires the library to be
4432 placed before the symbolic link pointing to it in the
4433 <file>.deb</file> file. This is so that when
4434 <prgn>dpkg</prgn> comes to install the symlink
4435 (overwriting the previous symlink pointing at an older
4436 version of the library), the new shared library is already
4437 in place. In the past, this was achieved by creating the
4438 library in the temporary packaging directory before
4439 creating the symlink. Unfortunately, this was not always
4440 effective, since the building of the tar file in the
4441 <file>.deb</file> depended on the behavior of the underlying
4442 file system. Some file systems (such as reiserfs) reorder
4443 the files so that the order of creation is forgotten.
4444 Since version 1.7.0, <prgn>dpkg</prgn>
4445 reorders the files itself as necessary when building a
4446 package. Thus it is no longer important to concern
4447 oneself with the order of file creation.
4451 <sect1 id="ldconfig">
4452 <heading><tt>ldconfig</tt></heading>
4455 Any package installing shared libraries in one of the default
4456 library directories of the dynamic linker (which are currently
4457 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4458 listed in <file>/etc/ld.so.conf</file><footnote>
4460 <list compact="compact">
4461 <item>/usr/X11R6/lib/Xaw3d</item>
4462 <item>/usr/local/lib</item>
4463 <item>/usr/lib/libc5-compat</item>
4464 <item>/lib/libc5-compat</item>
4465 <item>/usr/X11R6/lib</item>
4468 must use <prgn>ldconfig</prgn> to update the shared library
4473 The package must call <prgn>ldconfig</prgn> in the
4474 <prgn>postinst</prgn> script if the first argument is
4475 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4476 optionally invoke <prgn>ldconfig</prgn> at other times. The
4477 package should call <prgn>ldconfig</prgn> in the
4478 <prgn>postrm</prgn> script if the first argument is
4479 <tt>remove</tt>. The maintainer scripts must not invoke
4480 <prgn>ldconfig</prgn> under any circumstances other than those
4481 described in this paragraph.<footnote>
4483 During install or upgrade, the preinst is called before
4484 the new files are installed, so calling "ldconfig" is
4485 pointless. The preinst of an existing package can also be
4486 called if an upgrade fails. However, this happens during
4487 the critical time when a shared libs may exist on-disk
4488 under a temporary name. Thus, it is dangerous and
4489 forbidden by current policy to call "ldconfig" at this
4494 When a package is installed or upgraded, "postinst
4495 configure" runs after the new files are safely on-disk.
4496 Since it is perfectly safe to invoke ldconfig
4497 unconditionally in a postinst, it is OK for a package to
4498 simply put ldconfig in its postinst without checking the
4499 argument. The postinst can also be called to recover from
4500 a failed upgrade. This happens before any new files are
4501 unpacked, so there is no reason to call "ldconfig" at this
4506 For a package that is being removed, prerm is
4507 called with all the files intact, so calling ldconfig is
4508 useless. The other calls to "prerm" happen in the case of
4509 upgrade at a time when all the files of the old package
4510 are on-disk, so again calling "ldconfig" is pointless.
4514 postrm, on the other hand, is called with the "remove"
4515 argument just after the files are removed, so this is the
4516 proper time to call "ldconfig" to notify the system of the
4517 fact shared libraries from the package are removed.
4518 The postrm can be called at several other times. At the
4519 time of "postrm purge", "postrm abort-install", or "postrm
4520 abort-upgrade", calling "ldconfig" is useless because the
4521 shared lib files are not on-disk. However, when "postrm"
4522 is invoked with arguments "upgrade", "failed-upgrade", or
4523 "disappear", a shared lib may exist on-disk under a
4532 <sect id="sharedlibs-runtime-progs">
4533 <heading>Run-time support programs</heading>
4536 If your package has some run-time support programs which use
4537 the shared library you must not put them in the shared
4538 library package. If you do that then you won't be able to
4539 install several versions of the shared library without
4540 getting filename clashes.
4544 Instead, either create another package for the runtime binaries
4545 (this package might typically be named
4546 <package><var>libraryname</var>-runtime</package>; note the absence
4547 of the <var>soversion</var> in the package name), or if the
4548 development package is small, include them in there.
4552 <sect id="sharedlibs-static">
4553 <heading>Static libraries</heading>
4556 The static library (<file><var>libraryname.a</var></file>)
4557 is usually provided in addition to the shared version.
4558 It is placed into the development package (see below).
4562 In some cases, it is acceptable for a library to be
4563 available in static form only; these cases include:
4565 <item>libraries for languages whose shared library support
4566 is immature or unstable</item>
4567 <item>libraries whose interfaces are in flux or under
4568 development (commonly the case when the library's
4569 major version number is zero, or where the ABI breaks
4570 across patchlevels)</item>
4571 <item>libraries which are explicitly intended to be
4572 available only in static form by their upstream
4577 <sect id="sharedlibs-dev">
4578 <heading>Development files</heading>
4581 The development files associated to a shared library need to be
4582 placed in a package called
4583 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4584 or if you prefer only to support one development version at a
4585 time, <package><var>libraryname</var>-dev</package>.
4589 In case several development versions of a library exist, you may
4590 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4591 <ref id="conflicts">) to ensure that the user only installs one
4592 development version at a time (as different development versions are
4593 likely to have the same header files in them, which would cause a
4594 filename clash if both were installed).
4598 The development package should contain a symlink for the associated
4599 shared library without a version number. For example, the
4600 <package>libgdbm-dev</package> package should include a symlink
4601 from <file>/usr/lib/libgdbm.so</file> to
4602 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4603 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4604 <file>libgdbm.so</file> when compiling dynamically.
4608 <sect id="sharedlibs-intradeps">
4609 <heading>Dependencies between the packages of the same library</heading>
4612 Typically the development version should have an exact
4613 version dependency on the runtime library, to make sure that
4614 compilation and linking happens correctly. The
4615 <tt>${Source-Version}</tt> substitution variable can be
4616 useful for this purpose.
4620 <sect id="sharedlibs-shlibdeps">
4621 <heading>Dependencies between the library and other packages -
4622 the <tt>shlibs</tt> system</heading>
4625 If a package contains a binary or library which links to a
4626 shared library, we must ensure that when the package is
4627 installed on the system, all of the libraries needed are
4628 also installed. This requirement led to the creation of the
4629 <tt>shlibs</tt> system, which is very simple in its design:
4630 any package which <em>provides</em> a shared library also
4631 provides information on the package dependencies required to
4632 ensure the presence of this library, and any package which
4633 <em>uses</em> a shared library uses this information to
4634 determine the dependencies it requires. The files which
4635 contain the mapping from shared libraries to the necessary
4636 dependency information are called <file>shlibs</file> files.
4640 Thus, when a package is built which contains any shared
4641 libraries, it must provide a <file>shlibs</file> file for other
4642 packages to use, and when a package is built which contains
4643 any shared libraries or compiled binaries, it must run
4644 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4645 on these to determine the libraries used and hence the
4646 dependencies needed by this package.<footnote>
4648 In the past, the shared libraries linked to were
4649 determined by calling <prgn>ldd</prgn>, but now
4650 <prgn>objdump</prgn> is used to do this. The only
4651 change this makes to package building is that
4652 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4653 libraries, whereas in the past this was unnecessary.
4654 The rest of this footnote explains the advantage that
4659 We say that a binary <tt>foo</tt> <em>directly</em> uses
4660 a library <tt>libbar</tt> if it is explicitly linked
4661 with that library (that is, it uses the flag
4662 <tt>-lbar</tt> during the linking stage). Other
4663 libraries that are needed by <tt>libbar</tt> are linked
4664 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4665 linker will load them automatically when it loads
4666 <tt>libbar</tt>. A package should depend on
4667 the libraries it directly uses, and the dependencies for
4668 those libraries should automatically pull in the other
4673 Unfortunately, the <prgn>ldd</prgn> program shows both
4674 the directly and indirectly used libraries, meaning that
4675 the dependencies determined included both direct and
4676 indirect dependencies. The use of <prgn>objdump</prgn>
4677 avoids this problem by determining only the directly
4682 A good example of where this helps is the following. We
4683 could update <tt>libimlib</tt> with a new version that
4684 supports a new graphics format called dgf (but retaining
4685 the same major version number). If we used the old
4686 <prgn>ldd</prgn> method, every package that uses
4687 <tt>libimlib</tt> would need to be recompiled so it
4688 would also depend on <tt>libdgf</tt> or it wouldn't run
4689 due to missing symbols. However with the new system,
4690 packages using <tt>libimlib</tt> can rely on
4691 <tt>libimlib</tt> itself having the dependency on
4692 <tt>libdgf</tt> and so they would not need rebuilding.
4698 In the following sections, we will first describe where the
4699 various <tt>shlibs</tt> files are to be found, then how to
4700 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4701 file format and how to create them if your package contains a
4706 <heading>The <tt>shlibs</tt> files present on the system</heading>
4709 There are several places where <tt>shlibs</tt> files are
4710 found. The following list gives them in the order in which
4712 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4713 (The first one which gives the required information is used.)
4719 <p><file>debian/shlibs.local</file></p>
4722 This lists overrides for this package. Its use is
4723 described below (see <ref id="shlibslocal">).
4728 <p><file>/etc/dpkg/shlibs.override</file></p>
4731 This lists global overrides. This list is normally
4732 empty. It is maintained by the local system
4738 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4741 When packages are being built, any
4742 <file>debian/shlibs</file> files are copied into the
4743 control file area of the temporary build directory and
4744 given the name <file>shlibs</file>. These files give
4745 details of any shared libraries included in the
4747 An example may help here. Let us say that the
4748 source package <tt>foo</tt> generates two binary
4749 packages, <tt>libfoo2</tt> and
4750 <tt>foo-runtime</tt>. When building the binary
4751 packages, the two packages are created in the
4752 directories <file>debian/libfoo2</file> and
4753 <file>debian/foo-runtime</file> respectively.
4754 (<file>debian/tmp</file> could be used instead of one
4755 of these.) Since <tt>libfoo2</tt> provides the
4756 <tt>libfoo</tt> shared library, it will require a
4757 <tt>shlibs</tt> file, which will be installed in
4758 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4760 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4761 when <prgn>dpkg-shlibdeps</prgn> is run on the
4763 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4765 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4766 determine whether <tt>foo-prog</tt>'s library
4767 dependencies are satisfied by any of the libraries
4768 provided by <tt>libfoo2</tt>. For this reason,
4769 <prgn>dpkg-shlibdeps</prgn> must only be run once
4770 all of the individual binary packages'
4771 <tt>shlibs</tt> files have been installed into the
4778 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4781 These are the <file>shlibs</file> files corresponding to
4782 all of the packages installed on the system, and are
4783 maintained by the relevant package maintainers.
4788 <p><file>/etc/dpkg/shlibs.default</file></p>
4791 This file lists any shared libraries whose packages
4792 have failed to provide correct <file>shlibs</file> files.
4793 It was used when the <file>shlibs</file> setup was first
4794 introduced, but it is now normally empty. It is
4795 maintained by the <tt>dpkg</tt> maintainer.
4803 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4804 <file>shlibs</file> files</heading>
4808 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4809 into your <file>debian/rules</file> file. If your package
4810 contains only compiled binaries and libraries (but no scripts),
4811 you can use a command such as:
4812 <example compact="compact">
4813 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4814 debian/tmp/usr/lib/*
4816 Otherwise, you will need to explicitly list the compiled
4817 binaries and libraries.<footnote>
4818 If you are using <tt>debhelper</tt>, the
4819 <prgn>dh_shlibdeps</prgn> program will do this work for
4820 you. It will also correctly handle multi-binary
4826 This command puts the dependency information into the
4827 <file>debian/substvars</file> file, which is then used by
4828 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4829 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4830 field in the control file for this to work.
4834 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4835 done. If it does complain you might need to create your own
4836 <file>debian/shlibs.local</file> file, as explained below (see
4837 <ref id="shlibslocal">).
4841 If you have multiple binary packages, you will need to call
4842 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4843 compiled libraries or binaries. In such a case, you will
4844 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4845 utilities to specify a different <file>substvars</file> file.
4849 For more details on dpkg-shlibdeps, please see
4850 <ref id="pkg-dpkg-shlibdeps"> and
4851 <manref name="dpkg-shlibdeps" section="1">.
4856 <heading>The <file>shlibs</file> File Format</heading>
4859 Each <file>shlibs</file> file has the same format. Lines
4860 beginning with <tt>#</tt> are considered to be comments and
4861 are ignored. Each line is of the form:
4862 <example compact="compact">
4863 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4868 We will explain this by reference to the example of the
4869 <tt>zlib1g</tt> package, which (at the time of writing)
4870 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4874 <var>library-name</var> is the name of the shared library,
4875 in this case <tt>libz</tt>. (This must match the name part
4876 of the soname, see below.)
4880 <var>soname-version-number</var> is the version part of the
4881 soname of the library. The soname is the thing that must
4882 exactly match for the library to be recognized by the
4883 dynamic linker, and is usually of the form
4884 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4885 example, <tt>libz.so.1</tt>.<footnote>
4886 This can be determined using the command
4887 <example compact="compact">
4888 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4891 The version part is the part which comes after
4892 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4896 <var>dependencies</var> has the same syntax as a dependency
4897 field in a binary package control file. It should give
4898 details of which packages are required to satisfy a binary
4899 built against the version of the library contained in the
4900 package. See <ref id="depsyntax"> for details.
4904 In our example, if the first version of the <tt>zlib1g</tt>
4905 package which contained a minor number of at least
4906 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4907 <tt>shlibs</tt> entry for this library could say:
4908 <example compact="compact">
4909 libz 1 zlib1g (>= 1:1.1.3)
4911 The version-specific dependency is to avoid warnings from
4912 the dynamic linker about using older shared libraries with
4918 <heading>Providing a <file>shlibs</file> file</heading>
4921 If your package provides a shared library, you should create
4922 a <file>shlibs</file> file following the format described above.
4923 It is usual to call this file <file>debian/shlibs</file> (but if
4924 you have multiple binary packages, you might want to call it
4925 <file>debian/shlibs.<var>package</var></file> instead). Then
4926 let <file>debian/rules</file> install it in the control area:
4927 <example compact="compact">
4928 install -m644 debian/shlibs debian/tmp/DEBIAN
4930 or, in the case of a multi-binary package:
4931 <example compact="compact">
4932 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4934 An alternative way of doing this is to create the
4935 <file>shlibs</file> file in the control area directly from
4936 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4937 file at all,<footnote>
4938 This is what <prgn>dh_makeshlibs</prgn> in the
4939 <tt>debhelper</tt> suite does.
4941 since the <file>debian/shlibs</file> file itself is ignored by
4942 <prgn>dpkg-shlibdeps</prgn>.
4946 As <prgn>dpkg-shlibdeps</prgn> reads the
4947 <file>DEBIAN/shlibs</file> files in all of the binary packages
4948 being built from this source package, all of the
4949 <file>DEBIAN/shlibs</file> files should be installed before
4950 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4955 <sect1 id="shlibslocal">
4956 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4959 This file is intended only as a <em>temporary</em> fix if
4960 your binaries or libraries depend on a library whose package
4961 does not yet provide a correct <file>shlibs</file> file.
4965 We will assume that you are trying to package a binary
4966 <tt>foo</tt>. When you try running
4967 <prgn>dpkg-shlibdeps</prgn> you get the following error
4968 message (<tt>-O</tt> displays the dependency information on
4969 <tt>stdout</tt> instead of writing it to
4970 <tt>debian/substvars</tt>, and the lines have been wrapped
4971 for ease of reading):
4972 <example compact="compact">
4973 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4974 dpkg-shlibdeps: warning: unable to find dependency
4975 information for shared library libbar (soname 1,
4976 path /usr/lib/libbar.so.1, dependency field Depends)
4977 shlibs:Depends=libc6 (>= 2.2.2-2)
4979 You can then run <prgn>ldd</prgn> on the binary to find the
4980 full location of the library concerned:
4981 <example compact="compact">
4983 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4984 libc.so.6 => /lib/libc.so.6 (0x40032000)
4985 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4987 So the <prgn>foo</prgn> binary depends on the
4988 <prgn>libbar</prgn> shared library, but no package seems to
4989 provide a <file>*.shlibs</file> file handling
4990 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4991 determine the package responsible:
4992 <example compact="compact">
4993 $ dpkg -S /usr/lib/libbar.so.1
4994 bar1: /usr/lib/libbar.so.1
4995 $ dpkg -s bar1 | grep Version
4998 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4999 is the one we are using. Now we can file a bug against the
5000 <tt>bar1</tt> package and create our own
5001 <file>debian/shlibs.local</file> to locally fix the problem.
5002 Including the following line into your
5003 <file>debian/shlibs.local</file> file:
5004 <example compact="compact">
5005 libbar 1 bar1 (>= 1.0-1)
5007 should allow the package build to work.
5011 As soon as the maintainer of <tt>bar1</tt> provides a
5012 correct <file>shlibs</file> file, you should remove this line
5013 from your <file>debian/shlibs.local</file> file. (You should
5014 probably also then have a versioned <tt>Build-Depends</tt>
5015 on <tt>bar1</tt> to help ensure that others do not have the
5016 same problem building your package.)
5025 <chapt id="opersys"><heading>The Operating System</heading>
5028 <heading>Filesystem hierarchy</heading>
5032 <heading>Filesystem Structure</heading>
5035 The location of all installed files and directories must
5036 comply with the Filesystem Hierarchy Standard (FHS),
5037 version 2.1, except where doing so would violate other
5038 terms of Debian Policy. The version of this document
5039 referred here can be found in the <tt>debian-policy</tt>
5041 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5042 name="FHS (Debian copy)"> alongside this manual (or, if
5043 you have the <package>debian-policy</package> installed,
5045 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5046 (local copy)">). The
5047 latest version, which may be a more recent version, may
5049 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5050 Specific questions about following the standard may be
5051 asked on the <tt>debian-devel</tt> mailing list, or
5052 referred to the FHS mailing list (see the
5053 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5059 <heading>Site-specific programs</heading>
5062 As mandated by the FHS, packages must not place any
5063 files in <file>/usr/local</file>, either by putting them in
5064 the file system archive to be unpacked by <prgn>dpkg</prgn>
5065 or by manipulating them in their maintainer scripts.
5069 However, the package may create empty directories below
5070 <file>/usr/local</file> so that the system administrator knows
5071 where to place site-specific files. These directories
5072 should be removed on package removal if they are
5077 Note, that this applies only to directories <em>below</em>
5078 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5079 Packages must not create sub-directories in the directory
5080 <file>/usr/local</file> itself, except those listed in FHS,
5081 section 4.5. However, you may create directories below
5082 them as you wish. You must not remove any of the
5083 directories listed in 4.5, even if you created them.
5087 Since <file>/usr/local</file> can be mounted read-only from a
5088 remote server, these directories must be created and
5089 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5090 maintainer scripts and not be included in the
5091 <file>.deb</file> archive. These scripts must not fail if
5092 either of these operations fail.
5096 For example, the <tt>emacsen-common</tt> package could
5097 contain something like
5098 <example compact="compact">
5099 if [ ! -e /usr/local/share/emacs ]
5101 if mkdir /usr/local/share/emacs 2>/dev/null
5103 chown root:staff /usr/local/share/emacs
5104 chmod 2775 /usr/local/share/emacs
5108 in its <prgn>postinst</prgn> script, and
5109 <example compact="compact">
5110 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5111 rmdir /usr/local/share/emacs 2>/dev/null || true
5113 in the <prgn>prerm</prgn> script. (Note that this form is
5114 used to ensure that if the script is interrupted, the
5115 directory <file>/usr/local/share/emacs</file> will still be
5120 If you do create a directory in <file>/usr/local</file> for
5121 local additions to a package, you should ensure that
5122 settings in <file>/usr/local</file> take precedence over the
5123 equivalents in <file>/usr</file>.
5127 However, because <file>/usr/local</file> and its contents are
5128 for exclusive use of the local administrator, a package
5129 must not rely on the presence or absence of files or
5130 directories in <file>/usr/local</file> for normal operation.
5134 The <file>/usr/local</file> directory itself and all the
5135 subdirectories created by the package should (by default) have
5136 permissions 2775 (group-writable and set-group-id) and be
5137 owned by <tt>root.staff</tt>.
5142 <heading>The system-wide mail directory</heading>
5144 The system-wide mail directory is <file>/var/mail</file>. This
5145 directory is part of the base system and should not owned
5146 by any particular mail agents. The use of the old
5147 location <file>/var/spool/mail</file> is deprecated, even
5148 though the spool may still be physically located there.
5149 To maintain partial upgrade compatibility for systems
5150 which have <file>/var/spool/mail</file> as their physical mail
5151 spool, packages using <file>/var/mail</file> must depend on
5152 either <package>libc6</package> (>= 2.1.3-13), or on
5153 <package>base-files</package> (>= 2.2.0), or on later
5154 versions of either one of these packages.
5160 <heading>Users and groups</heading>
5163 <heading>Introduction</heading>
5165 The Debian system can be configured to use either plain or
5170 Some user ids (UIDs) and group ids (GIDs) are reserved
5171 globally for use by certain packages. Because some
5172 packages need to include files which are owned by these
5173 users or groups, or need the ids compiled into binaries,
5174 these ids must be used on any Debian system only for the
5175 purpose for which they are allocated. This is a serious
5176 restriction, and we should avoid getting in the way of
5177 local administration policies. In particular, many sites
5178 allocate users and/or local system groups starting at 100.
5182 Apart from this we should have dynamically allocated ids,
5183 which should by default be arranged in some sensible
5184 order, but the behavior should be configurable.
5188 Packages other than <tt>base-passwd</tt> must not modify
5189 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5190 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5195 <heading>UID and GID classes</heading>
5197 The UID and GID numbers are divided into classes as
5203 Globally allocated by the Debian project, the same
5204 on every Debian system. These ids will appear in
5205 the <file>passwd</file> and <file>group</file> files of all
5206 Debian systems, new ids in this range being added
5207 automatically as the <tt>base-passwd</tt> package is
5212 Packages which need a single statically allocated
5213 uid or gid should use one of these; their
5214 maintainers should ask the <tt>base-passwd</tt>
5222 Dynamically allocated system users and groups.
5223 Packages which need a user or group, but can have
5224 this user or group allocated dynamically and
5225 differently on each system, should use <tt>adduser
5226 --system</tt> to create the group and/or user.
5227 <prgn>adduser</prgn> will check for the existence of
5228 the user or group, and if necessary choose an unused
5229 id based on the ranges specified in
5230 <file>adduser.conf</file>.
5234 <tag>1000-29999:</tag>
5237 Dynamically allocated user accounts. By default
5238 <prgn>adduser</prgn> will choose UIDs and GIDs for
5239 user accounts in this range, though
5240 <file>adduser.conf</file> may be used to modify this
5245 <tag>30000-59999:</tag>
5250 <tag>60000-64999:</tag>
5253 Globally allocated by the Debian project, but only
5254 created on demand. The ids are allocated centrally
5255 and statically, but the actual accounts are only
5256 created on users' systems on demand.
5260 These ids are for packages which are obscure or
5261 which require many statically-allocated ids. These
5262 packages should check for and create the accounts in
5263 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5264 <prgn>adduser</prgn> if it has this facility) if
5265 necessary. Packages which are likely to require
5266 further allocations should have a "hole" left after
5267 them in the allocation, to give them room to
5272 <tag>65000-65533:</tag>
5280 User <tt>nobody</tt>. The corresponding gid refers
5281 to the group <tt>nogroup</tt>.
5288 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5289 not</em> be used, because it is the error return
5298 <sect id="sysvinit">
5299 <heading>System run levels and <file>init.d</file> scripts</heading>
5301 <sect1 id="/etc/init.d">
5302 <heading>Introduction</heading>
5305 The <file>/etc/init.d</file> directory contains the scripts
5306 executed by <prgn>init</prgn> at boot time and when the
5307 init state (or "runlevel") is changed (see <manref
5308 name="init" section="8">).
5312 There are at least two different, yet functionally
5313 equivalent, ways of handling these scripts. For the sake
5314 of simplicity, this document describes only the symbolic
5315 link method. However, it must not be assumed by maintainer
5316 scripts that this method is being used, and any automated
5317 manipulation of the various runlevel behaviours by
5318 maintainer scripts must be performed using
5319 <prgn>update-rc.d</prgn> as described below and not by
5320 manually installing or removing symlinks. For information
5321 on the implementation details of the other method,
5322 implemented in the <tt>file-rc</tt> package, please refer
5323 to the documentation of that package.
5327 These scripts are referenced by symbolic links in the
5328 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5329 runlevels, <prgn>init</prgn> looks in the directory
5330 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5331 execute, where <tt><var>n</var></tt> is the runlevel that
5332 is being changed to, or <tt>S</tt> for the boot-up
5337 The names of the links all have the form
5338 <file>S<var>mm</var><var>script</var></file> or
5339 <file>K<var>mm</var><var>script</var></file> where
5340 <var>mm</var> is a two-digit number and <var>script</var>
5341 is the name of the script (this should be the same as the
5342 name of the actual script in <file>/etc/init.d</file>).
5346 When <prgn>init</prgn> changes runlevel first the targets
5347 of the links whose names start with a <tt>K</tt> are
5348 executed, each with the single argument <tt>stop</tt>,
5349 followed by the scripts prefixed with an <tt>S</tt>, each
5350 with the single argument <tt>start</tt>. (The links are
5351 those in the <file>/etc/rc<var>n</var>.d</file> directory
5352 corresponding to the new runlevel.) The <tt>K</tt> links
5353 are responsible for killing services and the <tt>S</tt>
5354 link for starting services upon entering the runlevel.
5358 For example, if we are changing from runlevel 2 to
5359 runlevel 3, init will first execute all of the <tt>K</tt>
5360 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5361 all of the <tt>S</tt> prefixed scripts in that directory.
5362 The links starting with <tt>K</tt> will cause the
5363 referred-to file to be executed with an argument of
5364 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5369 The two-digit number <var>mm</var> is used to determine
5370 the order in which to run the scripts: low-numbered links
5371 have their scripts run first. For example, the
5372 <tt>K20</tt> scripts will be executed before the
5373 <tt>K30</tt> scripts. This is used when a certain service
5374 must be started before another. For example, the name
5375 server <prgn>bind</prgn> might need to be started before
5376 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5377 can set up its access lists. In this case, the script
5378 that starts <prgn>bind</prgn> would have a lower number
5379 than the script that starts <prgn>inn</prgn> so that it
5381 <example compact="compact">
5388 The two runlevels 0 (halt) and 6 (reboot) are slightly
5389 different. In these runlevels, the links with an
5390 <tt>S</tt> prefix are still called after those with a
5391 <tt>K</tt> prefix, but they too are called with the single
5392 argument <tt>stop</tt>.
5396 Also, if the script name ends <tt>.sh</tt>, the script
5397 will be sourced in runlevel <tt>S</tt> rather that being
5398 run in a forked subprocess, but will be explicitly run by
5399 <prgn>sh</prgn> in all other runlevels.
5404 <heading>Writing the scripts</heading>
5407 Packages that include daemons for system services should
5408 place scripts in <file>/etc/init.d</file> to start or stop
5409 services at boot time or during a change of runlevel.
5410 These scripts should be named
5411 <file>/etc/init.d/<var>package</var></file>, and they should
5412 accept one argument, saying what to do:
5415 <tag><tt>start</tt></tag>
5416 <item>start the service,</item>
5418 <tag><tt>stop</tt></tag>
5419 <item>stop the service,</item>
5421 <tag><tt>restart</tt></tag>
5422 <item>stop and restart the service if it's already running,
5423 otherwise start the service</item>
5425 <tag><tt>reload</tt></tag>
5426 <item><p>cause the configuration of the service to be
5427 reloaded without actually stopping and restarting
5430 <tag><tt>force-reload</tt></tag>
5431 <item>cause the configuration to be reloaded if the
5432 service supports this, otherwise restart the
5436 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5437 <tt>force-reload</tt> options should be supported by all
5438 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5443 The <file>init.d</file> scripts should ensure that they will
5444 behave sensibly if invoked with <tt>start</tt> when the
5445 service is already running, or with <tt>stop</tt> when it
5446 isn't, and that they don't kill unfortunately-named user
5447 processes. The best way to achieve this is usually to use
5448 <prgn>start-stop-daemon</prgn>.
5452 If a service reloads its configuration automatically (as
5453 in the case of <prgn>cron</prgn>, for example), the
5454 <tt>reload</tt> option of the <file>init.d</file> script
5455 should behave as if the configuration has been reloaded
5460 The <file>/etc/init.d</file> scripts must be treated as
5461 configuration files, either (if they are present in the
5462 package, that is, in the .deb file) by marking them as
5463 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5464 by managing them correctly in the maintainer scripts (see
5465 <ref id="config-files">). This is important since we want
5466 to give the local system administrator the chance to adapt
5467 the scripts to the local system, e.g., to disable a
5468 service without de-installing the package, or to specify
5469 some special command line options when starting a service,
5470 while making sure their changes aren't lost during the next
5475 These scripts should not fail obscurely when the
5476 configuration files remain but the package has been
5477 removed, as configuration files remain on the system after
5478 the package has been removed. Only when <prgn>dpkg</prgn>
5479 is executed with the <tt>--purge</tt> option will
5480 configuration files be removed. In particular, as the
5481 <file>/etc/init.d/<var>package</var></file> script itself is
5482 usually a <tt>conffile</tt>, it will remain on the system
5483 if the package is removed but not purged. Therefore, you
5484 should include a <tt>test</tt> statement at the top of the
5486 <example compact="compact">
5487 test -f <var>program-executed-later-in-script</var> || exit 0
5492 Often there are some variables in the <file>init.d</file>
5493 scripts whose values control the behaviour of the scripts,
5494 and which a system administrator is likely to want to
5495 change. As the scripts themselves are frequently
5496 <tt>conffile</tt>s, modifying them requires that the
5497 administrator merge in their changes each time the package
5498 is upgraded and the <tt>conffile</tt> changes. To ease
5499 the burden on the system administrator, such configurable
5500 values should not be placed directly in the script.
5501 Instead, they should be placed in a file in
5502 <file>/etc/default</file>, which typically will have the same
5503 base name as the <file>init.d</file> script. This extra file
5504 should be sourced by the script when the script runs. It
5505 must contain only variable settings and comments in POSIX
5506 <prgn>sh</prgn> format. It may either be a
5507 <tt>conffile</tt> or a configuration file maintained by
5508 the package maintainer scripts. See <ref id="config-files">
5513 To ensure that vital configurable values are always
5514 available, the <file>init.d</file> script should set default
5515 values for each of the shell variables it uses, either
5516 before sourcing the <file>/etc/default/</file> file or
5517 afterwards using something like the <tt>:
5518 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5519 script must behave sensibly and not fail if the
5520 <file>/etc/default</file> file is deleted.
5525 <heading>Interfacing with the initscript system</heading>
5528 Maintainers should use the abstraction layer provided by
5529 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5530 programs to deal with initscripts in their packages'
5531 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5532 and <prgn>postrm</prgn>.
5536 Directly managing the /etc/rc?.d links and directly
5537 invoking the <file>/etc/init.d/</file> initscripts should
5538 be done only by packages providing the initscript
5539 subsystem (such as <prgn>sysv-rc</prgn> and
5540 <prgn>file-rc</prgn>).
5544 <heading>Managing the links</heading>
5547 The program <prgn>update-rc.d</prgn> is provided for
5548 package maintainers to arrange for the proper creation and
5549 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5550 or their functional equivalent if another method is being
5551 used. This may be used by maintainers in their packages'
5552 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5556 You must not include any <file>/etc/rc<var>n</var>.d</file>
5557 symbolic links in the actual archive or manually create or
5558 remove the symbolic links in maintainer scripts; you must
5559 use the <prgn>update-rc.d</prgn> program instead. (The
5560 former will fail if an alternative method of maintaining
5561 runlevel information is being used.) You must not include
5562 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5563 in the archive either. (Only the <tt>sysvinit</tt>
5568 By default <prgn>update-rc.d</prgn> will start services in
5569 each of the multi-user state runlevels (2, 3, 4, and 5)
5570 and stop them in the halt runlevel (0), the single-user
5571 runlevel (1) and the reboot runlevel (6). The system
5572 administrator will have the opportunity to customize
5573 runlevels by simply adding, moving, or removing the
5574 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5575 symbolic links are being used, or by modifying
5576 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5581 To get the default behavior for your package, put in your
5582 <prgn>postinst</prgn> script
5583 <example compact="compact">
5584 update-rc.d <var>package</var> defaults
5586 and in your <prgn>postrm</prgn>
5587 <example compact="compact">
5588 if [ "$1" = purge ]; then
5589 update-rc.d <var>package</var> remove
5591 </example>. Note that if your package changes runlevels
5592 or priority, you may have to remove and recreate the links,
5593 since otherwise the old links may persist. Refer to the
5594 documentation of <prgn>update-rc.d</prgn>.
5598 This will use a default sequence number of 20. If it does
5599 not matter when or in which order the <file>init.d</file>
5600 script is run, use this default. If it does, then you
5601 should talk to the maintainer of the <prgn>sysvinit</prgn>
5602 package or post to <tt>debian-devel</tt>, and they will
5603 help you choose a number.
5607 For more information about using <tt>update-rc.d</tt>,
5608 please consult its man page <manref name="update-rc.d"
5614 <heading>Running initscripts</heading>
5616 The program <prgn>invoke-rc.d</prgn> is provided to make
5617 it easier for package maintainers to properly invoke an
5618 initscript, obeying runlevel and other locally-defined
5619 constraints that might limit a package's right to start,
5620 stop and otherwise manage services. This program may be
5621 used by maintainers in their packages' scripts.
5625 The use of <prgn>invoke-rc.d</prgn> to invoke the
5626 <file>/etc/init.d/*</file> initscripts is strongly
5627 recommended<footnote>
5628 In the future, the use of invoke-rc.d to invoke
5629 initscripts shall be made mandatory. Maintainers are
5630 advised to switch to invoke-rc.d as soon as
5632 </footnote>, instead of calling them directly.
5636 By default, <prgn>invoke-rc.d</prgn> will pass any
5637 action requests (start, stop, reload, restart...) to the
5638 <file>/etc/init.d</file> script, filtering out requests
5639 to start or restart a service out of its intended
5644 Most packages will simply need to change:
5645 <example compact="compact">/etc/init.d/<package>
5646 <action></example> in their <prgn>postinst</prgn>
5647 and <prgn>prerm</prgn> scripts to:
5648 <example compact="compact">
5649 if which invoke-rc.d >/dev/null 2>&1; then
5650 invoke-rc.d <var>package</var> <action>
5652 /etc/init.d/<var>package</var> <action>
5658 A package should register its initscript services using
5659 <prgn>update-rc.d</prgn> before it tries to invoke them
5660 using <prgn>invoke-rc.d</prgn>. Invocation of
5661 unregistered services may fail.
5665 For more information about using
5666 <prgn>invoke-rc.d</prgn>, please consult its man page
5667 <manref name="invoke-rc.d" section="8">.
5673 <heading>Boot-time initialization</heading>
5676 There used to be another directory, <file>/etc/rc.boot</file>,
5677 which contained scripts which were run once per machine
5678 boot. This has been deprecated in favour of links from
5679 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5680 described in <ref id="/etc/init.d">. Packages must not
5681 place files in <file>/etc/rc.boot</file>.
5686 <heading>Example</heading>
5689 The <prgn>bind</prgn> DNS (nameserver) package wants to
5690 make sure that the nameserver is running in multiuser
5691 runlevels, and is properly shut down with the system. It
5692 puts a script in <file>/etc/init.d</file>, naming the script
5693 appropriately <tt>bind</tt>. As you can see, the script
5694 interprets the argument <tt>reload</tt> to send the
5695 nameserver a <tt>HUP</tt> signal (causing it to reload its
5696 configuration); this way the system administrator can say
5697 <tt>/etc/init.d/bind reload</tt> to reload the name
5698 server. The script has one configurable value, which can
5699 be used to pass parameters to the named program at
5700 startup; this value is read from
5701 <file>/etc/default/bind</file> (see below).
5705 <example compact="compact">
5708 # Original version by Robert Leslie
5709 # <rob@mars.org>, edited by iwj and cs
5711 test -x /usr/sbin/named || exit 0
5713 # Source defaults file.
5715 if [ -f /etc/default/bind ]; then
5722 echo -n "Starting domain name service: named"
5723 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5728 echo -n "Stopping domain name service: named"
5729 start-stop-daemon --stop --quiet \
5730 --pidfile /var/run/named.pid --exec /usr/sbin/named
5734 echo -n "Restarting domain name service: named"
5735 start-stop-daemon --stop --quiet --oknodo \
5736 --pidfile /var/run/named.pid --exec /usr/sbin/named
5737 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5741 force-reload|reload)
5742 echo -n "Reloading configuration of domain name service: named"
5743 start-stop-daemon --stop --signal 1 --quiet \
5744 --pidfile /var/run/named.pid --exec /usr/sbin/named
5748 echo "Usage: /etc/init.d/bind " \
5749 " {start|stop|restart|reload|force-reload}" >&2
5759 Complementing the above init script is a configuration
5760 file <file>/etc/default/bind</file>, which contains
5761 configurable parameters used by the script. This would be
5762 created by the <prgn>postinst</prgn> script if it was not
5763 already present, and removed on purge by the
5764 <prgn>postrm</prgn> script.
5765 <example compact="compact">
5766 # Specified parameters to pass to named. See named(8).
5767 # You may uncomment the following line, and edit to taste.
5773 Another example on which you can base your
5774 <file>/etc/init.d</file> scripts is found in
5775 <file>/etc/init.d/skeleton</file>.
5779 If this package is happy with the default setup from
5780 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5781 and having named running in all runlevels, it can say in
5782 its <prgn>postinst</prgn>:
5783 <example compact="compact">
5784 update-rc.d bind defaults >/dev/null
5786 And in its <prgn>postrm</prgn>, to remove the links when the
5788 <example compact="compact">
5789 if [ "$1" = purge ]; then
5790 update-rc.d bind remove >/dev/null
5798 <heading>Console messages from <file>init.d</file> scripts</heading>
5801 This section describes the formats to be used for messages
5802 written to standard output by the <file>/etc/init.d</file>
5803 scripts. The intent is to improve the consistency of
5804 Debian's startup and shutdown look and feel. For this
5805 reason, please look very carefully at the details. We want
5806 the messages to have the same format in terms of wording,
5807 spaces, punctuation and case of letters.
5811 Here is a list of overall rules that should be used for
5812 messages generated by <file>/etc/init.d</file> scripts.
5818 The message should fit in one line (fewer than 80
5819 characters), start with a capital letter and end with
5820 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5824 If the script is performing some time consuming task in
5825 the background (not merely starting or stopping a
5826 program, for instance), an ellipsis (three dots:
5827 <tt>...</tt>) should be output to the screen, with no
5828 leading or tailing whitespace or line feeds.
5832 The messages should appear as if the computer is telling
5833 the user what it is doing (politely :-), but should not
5834 mention "it" directly. For example, instead of:
5835 <example compact="compact">
5836 I'm starting network daemons: nfsd mountd.
5838 the message should say
5839 <example compact="compact">
5840 Starting network daemons: nfsd mountd.
5847 <tt>init.d</tt> script should use the following standard
5848 message formats for the situations enumerated below.
5854 <p>When daemons are started</p>
5857 If the script starts one or more daemons, the output
5858 should look like this (a single line, no leading
5860 <example compact="compact">
5861 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5863 The <var>description</var> should describe the
5864 subsystem the daemon or set of daemons are part of,
5865 while <var>daemon-1</var> up to <var>daemon-n</var>
5866 denote each daemon's name (typically the file name of
5871 For example, the output of <file>/etc/init.d/lpd</file>
5873 <example compact="compact">
5874 Starting printer spooler: lpd.
5879 This can be achieved by saying
5880 <example compact="compact">
5881 echo -n "Starting printer spooler: lpd"
5882 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5885 in the script. If there are more than one daemon to
5886 start, the output should look like this:
5887 <example compact="compact">
5888 echo -n "Starting remote file system services:"
5889 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5890 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5891 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5894 This makes it possible for the user to see what is
5895 happening and when the final daemon has been started.
5896 Care should be taken in the placement of white spaces:
5897 in the example above the system administrators can
5898 easily comment out a line if they don't want to start
5899 a specific daemon, while the displayed message still
5905 <p>When a system parameter is being set</p>
5908 If you have to set up different system parameters
5909 during the system boot, you should use this format:
5910 <example compact="compact">
5911 Setting <var>parameter</var> to "<var>value</var>".
5916 You can use a statement such as the following to get
5918 <example compact="compact">
5919 echo "Setting DNS domainname to \"$domainname\"."
5924 Note that the same symbol (<tt>"</tt>) is used for the left
5925 and right quotation marks. A grave accent (<tt>`</tt>) is
5926 not a quote character; neither is an apostrophe
5932 <p>When a daemon is stopped or restarted</p>
5935 When you stop or restart a daemon, you should issue a
5936 message identical to the startup message, except that
5937 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5938 or <tt>Restarting</tt> respectively.
5942 For example, stopping the printer daemon will like
5944 <example compact="compact">
5945 Stopping printer spooler: lpd.
5951 <p>When something is executed</p>
5954 There are several examples where you have to run a
5955 program at system startup or shutdown to perform a
5956 specific task, for example, setting the system's clock
5957 using <prgn>netdate</prgn> or killing all processes
5958 when the system shuts down. Your message should look
5960 <example compact="compact">
5961 Doing something very useful...done.
5963 You should print the <tt>done.</tt> immediately after
5964 the job has been completed, so that the user is
5965 informed why they have to wait. You can get this
5967 <example compact="compact">
5968 echo -n "Doing something very useful..."
5977 <p>When the configuration is reloaded</p>
5980 When a daemon is forced to reload its configuration
5981 files you should use the following format:
5982 <example compact="compact">
5983 Reloading <var>description</var> configuration...done.
5985 where <var>description</var> is the same as in the
5986 daemon starting message.
5994 <heading>Cron jobs</heading>
5997 Packages must not modify the configuration file
5998 <file>/etc/crontab</file>, and they must not modify the files in
5999 <file>/var/spool/cron/crontabs</file>.</p>
6002 If a package wants to install a job that has to be executed
6003 via cron, it should place a file with the name of the
6004 package in one or more of the following directories:
6005 <example compact="compact">
6010 As these directory names imply, the files within them are
6011 executed on a daily, weekly, or monthly basis,
6012 respectively. The exact times are listed in
6013 <file>/etc/crontab</file>.</p>
6016 All files installed in any of these directories must be
6017 scripts (e.g., shell scripts or Perl scripts) so that they
6018 can easily be modified by the local system administrator.
6019 In addition, they should be treated as configuration
6024 If a certain job has to be executed more frequently than
6025 daily, the package should install a file
6026 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6027 same syntax as <file>/etc/crontab</file> and is processed by
6028 <prgn>cron</prgn> automatically. The file must also be
6029 treated as a configuration file. (Note that entries in the
6030 <file>/etc/cron.d</file> directory are not handled by
6031 <prgn>anacron</prgn>. Thus, you should only use this
6032 directory for jobs which may be skipped if the system is not
6036 The scripts or crontab entries in these directories should
6037 check if all necessary programs are installed before they
6038 try to execute them. Otherwise, problems will arise when a
6039 package was removed but not purged since configuration files
6040 are kept on the system in this situation.</p>
6044 <heading>Menus</heading>
6047 The Debian <tt>menu</tt> package provides a standard
6048 interface between packages providing applications and
6049 <em>menu programs</em> (either X window managers or
6050 text-based menu programs such as <prgn>pdmenu</prgn>).
6054 All packages that provide applications that need not be
6055 passed any special command line arguments for normal
6056 operation should register a menu entry for those
6057 applications, so that users of the <tt>menu</tt> package
6058 will automatically get menu entries in their window
6059 managers, as well in shells like <tt>pdmenu</tt>.
6063 Menu entries should follow the current menu policy.
6067 The menu policy can be found in the <tt>menu-policy</tt>
6068 files in the <tt>debian-policy</tt> package.
6069 It is also available from the Debian web mirrors at
6070 <tt><url name="/doc/packaging-manuals/menu-policy/"
6071 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6075 Please also refer to the <em>Debian Menu System</em>
6076 documentation that comes with the <package>menu</package>
6077 package for information about how to register your
6083 <heading>Multimedia handlers</heading>
6086 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6087 is a mechanism for encoding files and data streams and
6088 providing meta-information about them, in particular their
6089 type (e.g. audio or video) and format (e.g. PNG, HTML,
6094 Registration of MIME type handlers allows programs like mail
6095 user agents and web browsers to invoke these handlers to
6096 view, edit or display MIME types they don't support directly.
6100 Packages which provide the ability to view/show/play,
6101 compose, edit or print MIME types should register themselves
6102 as such following the current MIME support policy.
6106 The MIME support policy can be found in the <tt>mime-policy</tt>
6107 files in the <tt>debian-policy</tt> package.
6108 It is also available from the Debian web mirrors at
6109 <tt><url name="/doc/packaging-manuals/mime-policy/"
6110 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6116 <heading>Keyboard configuration</heading>
6119 To achieve a consistent keyboard configuration so that all
6120 applications interpret a keyboard event the same way, all
6121 programs in the Debian distribution must be configured to
6122 comply with the following guidelines.
6126 The following keys must have the specified interpretations:
6129 <tag><tt><--</tt></tag>
6130 <item>delete the character to the left of the cursor</item>
6132 <tag><tt>Delete</tt></tag>
6133 <item>delete the character to the right of the cursor</item>
6135 <tag><tt>Control+H</tt></tag>
6136 <item>emacs: the help prefix</item>
6139 The interpretation of any keyboard events should be
6140 independent of the terminal that is used, be it a virtual
6141 console, an X terminal emulator, an rlogin/telnet session,
6146 The following list explains how the different programs
6147 should be set up to achieve this:
6153 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6157 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6161 X translations are set up to make
6162 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6163 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6164 is the vt220 escape code for the "delete character"
6165 key). This must be done by loading the X resources
6166 using <prgn>xrdb</prgn> on all local X displays, not
6167 using the application defaults, so that the
6168 translation resources used correspond to the
6169 <prgn>xmodmap</prgn> settings.
6173 The Linux console is configured to make
6174 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6175 generate <tt>ESC [ 3 ~</tt>.
6179 X applications are configured so that <tt><</tt>
6180 deletes left, and <tt>Delete</tt> deletes right. Motif
6181 applications already work like this.
6185 Terminals should have <tt>stty erase ^?</tt> .
6189 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6190 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6191 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6195 Emacs is programmed to map <tt>KB_Backspace</tt> or
6196 the <tt>stty erase</tt> character to
6197 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6198 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6199 <tt>^H</tt> to <tt>help</tt> as always.
6203 Other applications use the <tt>stty erase</tt>
6204 character and <tt>kdch1</tt> for the two delete keys,
6205 with ASCII DEL being "delete previous character" and
6206 <tt>kdch1</tt> being "delete character under
6214 This will solve the problem except for the following
6221 Some terminals have a <tt><--</tt> key that cannot
6222 be made to produce anything except <tt>^H</tt>. On
6223 these terminals Emacs help will be unavailable on
6224 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6225 character takes precedence in Emacs, and has been set
6226 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6227 available) can be used instead.
6231 Some operating systems use <tt>^H</tt> for <tt>stty
6232 erase</tt>. However, modern telnet versions and all
6233 rlogin versions propagate <tt>stty</tt> settings, and
6234 almost all UNIX versions honour <tt>stty erase</tt>.
6235 Where the <tt>stty</tt> settings are not propagated
6236 correctly, things can be made to work by using
6237 <tt>stty</tt> manually.
6241 Some systems (including previous Debian versions) use
6242 <prgn>xmodmap</prgn> to arrange for both
6243 <tt><--</tt> and <tt>Delete</tt> to generate
6244 <tt>KB_Delete</tt>. We can change the behavior of
6245 their X clients using the same X resources that we use
6246 to do it for our own clients, or configure our clients
6247 using their resources when things are the other way
6248 around. On displays configured like this
6249 <tt>Delete</tt> will not work, but <tt><--</tt>
6254 Some operating systems have different <tt>kdch1</tt>
6255 settings in their <tt>terminfo</tt> database for
6256 <tt>xterm</tt> and others. On these systems the
6257 <tt>Delete</tt> key will not work correctly when you
6258 log in from a system conforming to our policy, but
6259 <tt><--</tt> will.
6266 <heading>Environment variables</heading>
6269 A program must not depend on environment variables to get
6270 reasonable defaults. (That's because these environment
6271 variables would have to be set in a system-wide
6272 configuration file like <file>/etc/profile</file>, which is not
6273 supported by all shells.)
6277 If a program usually depends on environment variables for its
6278 configuration, the program should be changed to fall back to
6279 a reasonable default configuration if these environment
6280 variables are not present. If this cannot be done easily
6281 (e.g., if the source code of a non-free program is not
6282 available), the program must be replaced by a small
6283 "wrapper" shell script which sets the environment variables
6284 if they are not already defined, and calls the original program.
6288 Here is an example of a wrapper script for this purpose:
6290 <example compact="compact">
6292 BAR=${BAR:-/var/lib/fubar}
6294 exec /usr/lib/foo/foo "$@"
6299 Furthermore, as <file>/etc/profile</file> is a configuration
6300 file of the <prgn>base-files</prgn> package, other packages must
6301 not put any environment variables or other commands into that
6306 <sect id="doc-base">
6307 <heading>Registering Documents using doc-base</heading>
6310 The <package>doc-base</package> package implements a
6311 flexible mechanism for handling and presenting
6312 documentation. The recommended practice is for every Debian
6313 package that provides online documentation (other than just
6314 manual pages) to register these documents with
6315 <package>doc-base</package> by installing a
6316 <package>doc-base</package> control file via the
6317 <prgn/install-docs/ script at installation time and
6318 de-register the manuals again when the package is removed.
6321 Please refer to the documentation that comes with the
6322 <package>doc-base</package> package for information and
6331 <heading>Files</heading>
6334 <heading>Binaries</heading>
6337 Two different packages must not install programs with
6338 different functionality but with the same filenames. (The
6339 case of two programs having the same functionality but
6340 different implementations is handled via "alternatives" or
6341 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6342 <ref id="conflicts"> respectively.) If this case happens,
6343 one of the programs must be renamed. The maintainers should
6344 report this to the <tt>debian-devel</tt> mailing list and
6345 try to find a consensus about which program will have to be
6346 renamed. If a consensus cannot be reached, <em>both</em>
6347 programs must be renamed.
6351 By default, when a package is being built, any binaries
6352 created should include debugging information, as well as
6353 being compiled with optimization. You should also turn on
6354 as many reasonable compilation warnings as possible; this
6355 makes life easier for porters, who can then look at build
6356 logs for possible problems. For the C programming language,
6357 this means the following compilation parameters should be
6359 <example compact="compact">
6361 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6363 install -s # (or use strip on the files in debian/tmp)
6368 Note that by default all installed binaries should be stripped,
6369 either by using the <tt>-s</tt> flag to
6370 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6371 the binaries after they have been copied into
6372 <file>debian/tmp</file> but before the tree is made into a
6377 Although binaries in the build tree should be compiled with
6378 debugging information by default, it can often be difficult
6379 to debug programs if they are also subjected to compiler
6380 optimization. For this reason, it is recommended to support
6381 the standardized environment
6382 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6383 contain several flags to change how a package is compiled
6391 The presence of this string means that the package
6392 should be compiled with a minimum of optimization.
6393 For C programs, it is best to add <tt>-O0</tt>
6394 to <tt>CFLAGS</tt> (although this is usually the
6395 default). Some programs might fail to build or run at
6396 this level of optimization; it may be necessary to
6397 use <tt>-O1</tt>, for example.
6401 This string means that the debugging symbols should
6402 not be stripped from the binary during installation,
6403 so that debugging information may be included in the package.
6409 The following makefile snippet is an example of how one may
6410 implement the build options; you will probably have to
6411 massage this example in order to make it work for your
6413 <example compact="compact">
6416 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6417 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6418 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6419 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6421 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6426 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6427 INSTALL_PROGRAM += -s
6433 It is up to the package maintainer to decide what
6434 compilation options are best for the package. Certain
6435 binaries (such as computationally-intensive programs) will
6436 function better with certain flags (<tt>-O3</tt>, for
6437 example); feel free to use them. Please use good judgment
6438 here. Don't use flags for the sake of it; only use them
6439 if there is good reason to do so. Feel free to override
6440 the upstream author's ideas about which compilation
6441 options are best: they are often inappropriate for our
6447 <sect id="libraries">
6448 <heading>Libraries</heading>
6451 The shared version of a library must be compiled with
6452 <tt>-fPIC</tt>, and the static version must not be. In other
6453 words, each source unit (<tt>*.c</tt>, for example, for C files)
6454 will need to be compiled twice.
6458 You must specify the gcc option <tt>-D_REENTRANT</tt>
6459 when building a library (either static or shared) to make
6460 the library compatible with LinuxThreads.
6464 Although not enforced by the build tools, shared libraries
6465 must be linked against all libraries that they use symbols from
6466 in the same way that binaries are. This ensures the correct
6467 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6468 system and guarantees that all libraries can be safely opened
6469 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6470 option <tt>-Wl,-z,defs</tt> when building a shared library.
6471 Since this option enforces symbol resolution at build time,
6472 a missing library reference will be caught early as a fatal
6477 All installed shared libraries should be stripped with
6478 <example compact="compact">
6479 strip --strip-unneeded <var>your-lib</var>
6481 (The option <tt>--strip-unneeded</tt> makes
6482 <prgn>strip</prgn> remove only the symbols which aren't
6483 needed for relocation processing.) Shared libraries can
6484 function perfectly well when stripped, since the symbols for
6485 dynamic linking are in a separate part of the ELF object
6487 You might also want to use the options
6488 <tt>--remove-section=.comment</tt> and
6489 <tt>--remove-section=.note</tt> on both shared libraries
6490 and executables, and <tt>--strip-debug</tt> on static
6496 Note that under some circumstances it may be useful to
6497 install a shared library unstripped, for example when
6498 building a separate package to support debugging.
6502 Shared object files (often <file>.so</file> files) that are not
6503 public libraries, that is, they are not meant to be linked
6504 to by third party executables (binaries of other packages),
6505 should be installed in subdirectories of the
6506 <file>/usr/lib</file> directory. Such files are exempt from the
6507 rules that govern ordinary shared libraries, except that
6508 they must not be installed executable and should be
6510 A common example are the so-called "plug-ins",
6511 internal shared objects that are dynamically loaded by
6512 programs using <manref name="dlopen" section="3">.
6517 Packages containing shared libraries that may be linked to
6518 by other packages' binaries, but which for some
6519 <em>compelling</em> reason can not be installed in
6520 <file>/usr/lib</file> directory, may install the shared library
6521 files in subdirectories of the <file>/usr/lib</file> directory,
6522 in which case they should arrange to add that directory in
6523 <file>/etc/ld.so.conf</file> in the package's post-installation
6524 script, and remove it in the package's post-removal script.
6528 An ever increasing number of packages are using
6529 <prgn>libtool</prgn> to do their linking. The latest GNU
6530 libtools (>= 1.3a) can take advantage of the metadata in the
6531 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6532 files). The main advantage of <prgn>libtool</prgn>'s
6533 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6534 store and subsequently access metadata with respect to the
6535 libraries it builds. <prgn>libtool</prgn> will search for
6536 those files, which contain a lot of useful information about
6537 a library (such as library dependency information for static
6538 linking). Also, they're <em>essential</em> for programs
6539 using <tt>libltdl</tt>.<footnote>
6540 Although <prgn>libtool</prgn> is fully capable of
6541 linking against shared libraries which don't have
6542 <tt>.la</tt> files, as it is a mere shell script it can
6543 add considerably to the build time of a
6544 <prgn>libtool</prgn>-using package if that shell script
6545 has to derive all this information from first principles
6546 for each library every time it is linked. With the
6547 advent of <prgn>libtool</prgn> version 1.4 (and to a
6548 lesser extent <prgn>libtool</prgn> version 1.3), the
6549 <file>.la</file> files also store information about
6550 inter-library dependencies which cannot necessarily be
6551 derived after the <file>.la</file> file is deleted.
6556 Packages that use <prgn>libtool</prgn> to create shared
6557 libraries should include the <file>.la</file> files in the
6558 <tt>-dev</tt> package, unless the package relies on
6559 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6560 the <tt>.la</tt> files must go in the run-time library
6565 You must make sure that you use only released versions of
6566 shared libraries to build your packages; otherwise other
6567 users will not be able to run your binaries
6568 properly. Producing source packages that depend on
6569 unreleased compilers is also usually a bad
6576 <heading>Shared libraries</heading>
6578 This section has moved to <ref id="sharedlibs">.
6584 <heading>Scripts</heading>
6587 All command scripts, including the package maintainer
6588 scripts inside the package and used by <prgn>dpkg</prgn>,
6589 should have a <tt>#!</tt> line naming the shell to be used
6594 In the case of Perl scripts this should be
6595 <tt>#!/usr/bin/perl</tt>.
6599 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6600 should almost certainly start with <tt>set -e</tt> so that
6601 errors are detected. Every script should use
6602 <tt>set -e</tt> or check the exit status of <em>every</em>
6607 The standard shell interpreter <file>/bin/sh</file> can be a
6608 symbolic link to any POSIX compatible shell, if <tt>echo
6609 -n</tt> does not generate a newline.<footnote>
6610 Debian policy specifies POSIX behavior for
6611 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6612 use in the Linux community (in particular including this
6613 policy, the Linux kernel source, many Debian scripts,
6614 etc.). This <tt>echo -n</tt> mechanism is valid but not
6615 required under POSIX, hence this explicit addition.
6616 Also, rumour has it that this shall be mandated under
6619 Thus, shell scripts specifying <file>/bin/sh</file> as
6620 interpreter should only use POSIX features. If a script
6621 requires non-POSIX features from the shell interpreter, the
6622 appropriate shell must be specified in the first line of the
6623 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6624 depend on the package providing the shell (unless the shell
6625 package is marked "Essential", as in the case of
6630 You may wish to restrict your script to POSIX features when
6631 possible so that it may use <file>/bin/sh</file> as its
6632 interpreter. If your script works with <prgn>dash</prgn>
6633 (originally called <prgn>ash</prgn>), it's probably POSIX
6634 compliant, but if you are in doubt, use
6635 <file>/bin/bash</file>.
6639 Perl scripts should check for errors when making any
6640 system calls, including <tt>open</tt>, <tt>print</tt>,
6641 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6645 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6646 scripting languages. See <em>Csh Programming Considered
6647 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6648 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
6649 If an upstream package comes with <prgn>csh</prgn> scripts
6650 then you must make sure that they start with
6651 <tt>#!/bin/csh</tt> and make your package depend on the
6652 <prgn>c-shell</prgn> virtual package.
6656 Any scripts which create files in world-writeable
6657 directories (e.g., in <file>/tmp</file>) must use a
6658 mechanism which will fail if a file with the same name
6663 The Debian base system provides the <prgn>tempfile</prgn>
6664 and <prgn>mktemp</prgn> utilities for use by scripts for
6671 <heading>Symbolic links</heading>
6674 In general, symbolic links within a top-level directory
6675 should be relative, and symbolic links pointing from one
6676 top-level directory into another should be absolute. (A
6677 top-level directory is a sub-directory of the root
6678 directory <file>/</file>.)
6682 In addition, symbolic links should be specified as short as
6683 possible, i.e., link targets like <file>foo/../bar</file> are
6688 Note that when creating a relative link using
6689 <prgn>ln</prgn> it is not necessary for the target of the
6690 link to exist relative to the working directory you're
6691 running <prgn>ln</prgn> from, nor is it necessary to change
6692 directory to the directory where the link is to be made.
6693 Simply include the string that should appear as the target
6694 of the link (this will be a pathname relative to the
6695 directory in which the link resides) as the first argument
6700 For example, in your <prgn>Makefile</prgn> or
6701 <file>debian/rules</file>, you can do things like:
6702 <example compact="compact">
6703 ln -fs gcc $(prefix)/bin/cc
6704 ln -fs gcc debian/tmp/usr/bin/cc
6705 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6706 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6711 A symbolic link pointing to a compressed file should always
6712 have the same file extension as the referenced file. (For
6713 example, if a file <file>foo.gz</file> is referenced by a
6714 symbolic link, the filename of the link has to end with
6715 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6720 <heading>Device files</heading>
6723 Packages must not include device files in the package file
6728 If a package needs any special device files that are not
6729 included in the base system, it must call
6730 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6731 after notifying the user<footnote>
6732 This notification could be done via a (low-priority)
6733 debconf message, or an echo (printf) statement.
6738 Packages must not remove any device files in the
6739 <prgn>postrm</prgn> or any other script. This is left to the
6740 system administrator.
6744 Debian uses the serial devices
6745 <file>/dev/ttyS*</file>. Programs using the old
6746 <file>/dev/cu*</file> devices should be changed to use
6747 <file>/dev/ttyS*</file>.
6751 <sect id="config-files">
6752 <heading>Configuration files</heading>
6755 <heading>Definitions</heading>
6759 <tag>configuration file</tag>
6761 A file that affects the operation of a program, or
6762 provides site- or host-specific information, or
6763 otherwise customizes the behavior of a program.
6764 Typically, configuration files are intended to be
6765 modified by the system administrator (if needed or
6766 desired) to conform to local policy or to provide
6767 more useful site-specific behavior.
6770 <tag><tt>conffile</tt></tag>
6772 A file listed in a package's <tt>conffiles</tt>
6773 file, and is treated specially by <prgn>dpkg</prgn>
6774 (see <ref id="configdetails">).
6780 The distinction between these two is important; they are
6781 not interchangeable concepts. Almost all
6782 <tt>conffile</tt>s are configuration files, but many
6783 configuration files are not <tt>conffiles</tt>.
6787 Note that a script that embeds configuration information
6788 (such as most of the files in <file>/etc/default</file> and
6789 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6790 configuration file and should be treated as such.
6795 <heading>Location</heading>
6798 Any configuration files created or used by your package
6799 must reside in <file>/etc</file>. If there are several,
6800 consider creating a subdirectory of <file>/etc</file>
6801 named after your package.
6805 If your package creates or uses configuration files
6806 outside of <file>/etc</file>, and it is not feasible to modify
6807 the package to use <file>/etc</file> directly, put the files
6808 in <file>/etc</file> and create symbolic links to those files
6809 from the location that the package requires.
6814 <heading>Behavior</heading>
6817 Configuration file handling must conform to the following
6819 <list compact="compact">
6821 local changes must be preserved during a package
6825 configuration files must be preserved when the
6826 package is removed, and only deleted when the
6833 The easy way to achieve this behavior is to make the
6834 configuration file a <tt>conffile</tt>. This is
6835 appropriate only if it is possible to distribute a default
6836 version that will work for most installations, although
6837 some system administrators may choose to modify it. This
6838 implies that the default version will be part of the
6839 package distribution, and must not be modified by the
6840 maintainer scripts during installation (or at any other
6845 In order to ensure that local changes are preserved
6846 correctly, no package may contain or make hard links to
6847 conffiles.<footnote>
6848 Rationale: There are two problems with hard links.
6849 The first is that some editors break the link while
6850 editing one of the files, so that the two files may
6851 unwittingly become unlinked and different. The second
6852 is that <prgn>dpkg</prgn> might break the hard link
6853 while upgrading <tt>conffile</tt>s.
6858 The other way to do it is via the maintainer scripts. In
6859 this case, the configuration file must not be listed as a
6860 <tt>conffile</tt> and must not be part of the package
6861 distribution. If the existence of a file is required for
6862 the package to be sensibly configured it is the
6863 responsibility of the package maintainer to provide
6864 maintainer scripts which correctly create, update and
6865 maintain the file and remove it on purge. (See <ref
6866 id="maintainerscripts"> for more information.) These
6867 scripts must be idempotent (i.e., must work correctly if
6868 <prgn>dpkg</prgn> needs to re-run them due to errors
6869 during installation or removal), must cope with all the
6870 variety of ways <prgn>dpkg</prgn> can call maintainer
6871 scripts, must not overwrite or otherwise mangle the user's
6872 configuration without asking, must not ask unnecessary
6873 questions (particularly during upgrades), and otherwise be
6878 The scripts are not required to configure every possible
6879 option for the package, but only those necessary to get
6880 the package running on a given system. Ideally the
6881 sysadmin should not have to do any configuration other
6882 than that done (semi-)automatically by the
6883 <prgn>postinst</prgn> script.
6887 A common practice is to create a script called
6888 <file><var>package</var>-configure</file> and have the
6889 package's <prgn>postinst</prgn> call it if and only if the
6890 configuration file does not already exist. In certain
6891 cases it is useful for there to be an example or template
6892 file which the maintainer scripts use. Such files should
6893 be in <file>/usr/share/<var>package</var></file> or
6894 <file>/usr/lib/<var>package</var></file> (depending on whether
6895 they are architecture-independent or not). There should
6896 be symbolic links to them from
6897 <file>/usr/share/doc/<var>package</var>/examples</file> if
6898 they are examples, and should be perfectly ordinary
6899 <prgn>dpkg</prgn>-handled files (<em>not</em>
6900 configuration files).
6904 These two styles of configuration file handling must
6905 not be mixed, for that way lies madness:
6906 <prgn>dpkg</prgn> will ask about overwriting the file
6907 every time the package is upgraded.
6912 <heading>Sharing configuration files</heading>
6915 Packages which specify the same file as a
6916 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6917 with each other. (This is an instance of the general rule
6918 about not sharing files. Note that neither alternatives
6919 nor diversions are likely to be appropriate in this case;
6920 in particular, <prgn>dpkg</prgn> does not handle diverted
6921 <tt>conffile</tt>s well.)
6925 The maintainer scripts must not alter a <tt>conffile</tt>
6926 of <em>any</em> package, including the one the scripts
6931 If two or more packages use the same configuration file
6932 and it is reasonable for both to be installed at the same
6933 time, one of these packages must be defined as
6934 <em>owner</em> of the configuration file, i.e., it will be
6935 the package which handles that file as a configuration
6936 file. Other packages that use the configuration file must
6937 depend on the owning package if they require the
6938 configuration file to operate. If the other package will
6939 use the configuration file if present, but is capable of
6940 operating without it, no dependency need be declared.
6944 If it is desirable for two or more related packages to
6945 share a configuration file <em>and</em> for all of the
6946 related packages to be able to modify that configuration
6947 file, then the following should be done:
6948 <enumlist compact="compact">
6950 One of the related packages (the "owning" package)
6951 will manage the configuration file with maintainer
6952 scripts as described in the previous section.
6955 The owning package should also provide a program
6956 that the other packages may use to modify the
6960 The related packages must use the provided program
6961 to make any desired modifications to the
6962 configuration file. They should either depend on
6963 the core package to guarantee that the configuration
6964 modifier program is available or accept gracefully
6965 that they cannot modify the configuration file if it
6966 is not. (This is in addition to the fact that the
6967 configuration file may not even be present in the
6974 Sometimes it's appropriate to create a new package which
6975 provides the basic infrastructure for the other packages
6976 and which manages the shared configuration files. (The
6977 <tt>sgml-base</tt> package is a good example.)
6982 <heading>User configuration files ("dotfiles")</heading>
6985 The files in <file>/etc/skel</file> will automatically be
6986 copied into new user accounts by <prgn>adduser</prgn>.
6987 No other program should reference the files in
6988 <file>/etc/skel</file>.
6992 Therefore, if a program needs a dotfile to exist in
6993 advance in <file>$HOME</file> to work sensibly, that dotfile
6994 should be installed in <file>/etc/skel</file> and treated as a
6999 However, programs that require dotfiles in order to
7000 operate sensibly are a bad thing, unless they do create
7001 the dotfiles themselves automatically.
7005 Furthermore, programs should be configured by the Debian
7006 default installation to behave as closely to the upstream
7007 default behaviour as possible.
7011 Therefore, if a program in a Debian package needs to be
7012 configured in some way in order to operate sensibly, that
7013 should be done using a site-wide configuration file placed
7014 in <file>/etc</file>. Only if the program doesn't support a
7015 site-wide default configuration and the package maintainer
7016 doesn't have time to add it may a default per-user file be
7017 placed in <file>/etc/skel</file>.
7021 <file>/etc/skel</file> should be as empty as we can make it.
7022 This is particularly true because there is no easy (or
7023 necessarily desirable) mechanism for ensuring that the
7024 appropriate dotfiles are copied into the accounts of
7025 existing users when a package is installed.
7031 <heading>Log files</heading>
7033 Log files should usually be named
7034 <file>/var/log/<var>package</var>.log</file>. If you have many
7035 log files, or need a separate directory for permission
7036 reasons (<file>/var/log</file> is writable only by
7037 <file>root</file>), you should usually create a directory named
7038 <file>/var/log/<var>package</var></file> and place your log
7043 Log files must be rotated occasionally so that they don't
7044 grow indefinitely; the best way to do this is to drop a log
7045 rotation configuration file into the directory
7046 <file>/etc/logrotate.d</file> and use the facilities provided by
7047 logrotate.<footnote>
7049 The traditional approach to log files has been to set up
7050 <em>ad hoc</em> log rotation schemes using simple shell
7051 scripts and cron. While this approach is highly
7052 customizable, it requires quite a lot of sysadmin work.
7053 Even though the original Debian system helped a little
7054 by automatically installing a system which can be used
7055 as a template, this was deemed not enough.
7059 The use of <prgn>logrotate</prgn>, a program developed
7060 by Red Hat, is better, as it centralizes log management.
7061 It has both a configuration file
7062 (<file>/etc/logrotate.conf</file>) and a directory where
7063 packages can drop their individual log rotation
7064 configurations (<file>/etc/logrotate.d</file>).
7067 Here is a good example for a logrotate config
7068 file (for more information see <manref name="logrotate"
7070 <example compact="compact">
7071 /var/log/foo/*.log {
7076 /etc/init.d/foo force-reload
7080 This rotates all files under <file>/var/log/foo</file>, saves 12
7081 compressed generations, and forces the daemon to reload its
7082 configuration information after the log rotation.
7086 Log files should be removed when the package is
7087 purged (but not when it is only removed). This should be
7088 done by the <prgn>postrm</prgn> script when it is called
7089 with the argument <tt>purge</tt> (see <ref
7090 id="removedetails">).
7095 <heading>Permissions and owners</heading>
7098 The rules in this section are guidelines for general use.
7099 If necessary you may deviate from the details below.
7100 However, if you do so you must make sure that what is done
7101 is secure and you should try to be as consistent as possible
7102 with the rest of the system. You should probably also
7103 discuss it on <prgn>debian-devel</prgn> first.
7107 Files should be owned by <tt>root.root</tt>, and made
7108 writable only by the owner and universally readable (and
7109 executable, if appropriate), that is mode 644 or 755.
7113 Directories should be mode 755 or (for group-writability)
7114 mode 2775. The ownership of the directory should be
7115 consistent with its mode: if a directory is mode 2775, it
7116 should be owned by the group that needs write access to
7121 Setuid and setgid executables should be mode 4755 or 2755
7122 respectively, and owned by the appropriate user or group.
7123 They should not be made unreadable (modes like 4711 or
7124 2711 or even 4111); doing so achieves no extra security,
7125 because anyone can find the binary in the freely available
7126 Debian package; it is merely inconvenient. For the same
7127 reason you should not restrict read or execute permissions
7128 on non-set-id executables.
7132 Some setuid programs need to be restricted to particular
7133 sets of users, using file permissions. In this case they
7134 should be owned by the uid to which they are set-id, and by
7135 the group which should be allowed to execute them. They
7136 should have mode 4754; again there is no point in making
7137 them unreadable to those users who must not be allowed to
7142 It is possible to arrange that the system administrator can
7143 reconfigure the package to correspond to their local
7144 security policy by changing the permissions on a binary:
7145 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7146 described below.<footnote>
7147 Ordinary files installed by <prgn>dpkg</prgn> (as
7148 opposed to <tt>conffile</tt>s and other similar objects)
7149 normally have their permissions reset to the distributed
7150 permissions when the package is reinstalled. However,
7151 the use of <prgn>dpkg-statoverride</prgn> overrides this
7152 default behaviour. If you use this method, you should
7153 remember to describe <prgn>dpkg-statoverride</prgn> in
7154 the package documentation; being a relatively new
7155 addition to Debian, it is probably not yet well-known.
7157 Another method you should consider is to create a group for
7158 people allowed to use the program(s) and make any setuid
7159 executables executable only by that group.
7163 If you need to create a new user or group for your package
7164 there are two possibilities. Firstly, you may need to
7165 make some files in the binary package be owned by this
7166 user or group, or you may need to compile the user or
7167 group id (rather than just the name) into the binary
7168 (though this latter should be avoided if possible, as in
7169 this case you need a statically allocated id).</p>
7172 If you need a statically allocated id, you must ask for a
7173 user or group id from the <tt>base-passwd</tt> maintainer,
7174 and must not release the package until you have been
7175 allocated one. Once you have been allocated one you must
7176 either make the package depend on a version of the
7177 <tt>base-passwd</tt> package with the id present in
7178 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7179 your package to create the user or group itself with the
7180 correct id (using <tt>adduser</tt>) in its
7181 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7182 the <prgn>postinst</prgn> is to be preferred if it is
7183 possible, otherwise a pre-dependency will be needed on the
7184 <tt>adduser</tt> package.)
7188 On the other hand, the program might be able to determine
7189 the uid or gid from the user or group name at runtime, so
7190 that a dynamically allocated id can be used. In this case
7191 you should choose an appropriate user or group name,
7192 discussing this on <prgn>debian-devel</prgn> and checking
7193 with the <package/base-passwd/ maintainer that it is unique and that
7194 they do not wish you to use a statically allocated id
7195 instead. When this has been checked you must arrange for
7196 your package to create the user or group if necessary using
7197 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7198 <prgn>postinst</prgn> script (again, the latter is to be
7199 preferred if it is possible).
7203 Note that changing the numeric value of an id associated
7204 with a name is very difficult, and involves searching the
7205 file system for all appropriate files. You need to think
7206 carefully whether a static or dynamic id is required, since
7207 changing your mind later will cause problems.
7210 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7212 This section is not intended as policy, but as a
7213 description of the use of <prgn>dpkg-statoverride</prgn>.
7217 <prgn>dpkg-statoverride</prgn> is a replacement for the
7218 deprecated <tt>suidmanager</tt> package. Packages which
7219 previously used <tt>suidmanager</tt> should have a
7220 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7221 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7222 and <tt>suidunregister</tt> should now be simply removed
7223 from the maintainer scripts.
7227 If a system administrator wishes to have a file (or
7228 directory or other such thing) installed with owner and
7229 permissions different from those in the distributed Debian
7230 package, they can use the <prgn>dpkg-statoverride</prgn>
7231 program to instruct <prgn>dpkg</prgn> to use the different
7232 settings every time the file is installed. Thus the
7233 package maintainer should distribute the files with their
7234 normal permissions, and leave it for the system
7235 administrator to make any desired changes. For example, a
7236 daemon which is normally required to be setuid root, but
7237 in certain situations could be used without being setuid,
7238 should be installed setuid in the <tt>.deb</tt>. Then the
7239 local system administrator can change this if they wish.
7240 If there are two standard ways of doing it, the package
7241 maintainer can use <tt>debconf</tt> to find out the
7242 preference, and call <prgn>dpkg-statoverride</prgn> in the
7243 maintainer script if necessary to accommodate the system
7244 administrator's choice.
7248 Given the above, <prgn>dpkg-statoverride</prgn> is
7249 essentially a tool for system administrators and would not
7250 normally be needed in the maintainer scripts. There is
7251 one type of situation, though, where calls to
7252 <prgn>dpkg-statoverride</prgn> would be needed in the
7253 maintainer scripts, and that involves packages which use
7254 dynamically allocated user or group ids. In such a
7255 situation, something like the following idiom can be very
7256 helpful in the package's <prgn>postinst</prgn>, where
7257 <tt>sysuser</tt> is a dynamically allocated id:
7259 for i in /usr/bin/foo /usr/sbin/bar
7261 if ! dpkg-statoverride --list $i >/dev/null
7263 dpkg-statoverride --update --add sysuser root 4755 $i
7267 The corresponding <tt>dpkg-statoverride --remove</tt>
7268 calls can then be made unconditionally when the package is
7276 <chapt id="customized-programs">
7277 <heading>Customized programs</heading>
7279 <sect id="arch-spec">
7280 <heading>Architecture specification strings</heading>
7283 If a program needs to specify an <em>architecture specification
7284 string</em> in some place, the following format should be
7285 used: <var>arch</var>-<var>os</var><footnote>
7286 The following architectures and operating systems are
7287 currently recognised by <prgn>dpkg-architecture</prgn>.
7288 The architecture, <tt><var>arch</var></tt>, is one of
7289 the following: <tt>alpha</tt>, <tt>arm</tt>,
7290 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7291 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7292 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7293 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7294 operating system, <tt><var>os</var></tt>, is one of:
7295 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7296 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7297 reserved for the GNU/Hurd operating system.
7302 Note that we don't want to use
7303 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7304 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7305 since this would make our programs incompatible with other
7306 Linux distributions. We also don't use something like
7307 <tt><var>arch</var>-unknown-linux</tt>, since the
7308 <tt>unknown</tt> does not look very good.
7313 <heading>Daemons</heading>
7316 The configuration files <file>/etc/services</file>,
7317 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7318 by the <prgn>netbase</prgn> package and must not be modified
7323 If a package requires a new entry in one of these files, the
7324 maintainer should get in contact with the
7325 <prgn>netbase</prgn> maintainer, who will add the entries
7326 and release a new version of the <prgn>netbase</prgn>
7331 The configuration file <file>/etc/inetd.conf</file> must not be
7332 modified by the package's scripts except via the
7333 <prgn>update-inetd</prgn> script or the
7334 <file>DebianNet.pm</file> Perl module. See their documentation
7335 for details on how to add entries.
7339 If a package wants to install an example entry into
7340 <file>/etc/inetd.conf</file>, the entry must be preceded with
7341 exactly one hash character (<tt>#</tt>). Such lines are
7342 treated as "commented out by user" by the
7343 <prgn>update-inetd</prgn> script and are not changed or
7344 activated during package updates.
7349 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7353 Some programs need to create pseudo-ttys. This should be done
7354 using Unix98 ptys if the C library supports it. The resulting
7355 program must not be installed setuid root, unless that
7356 is required for other functionality.
7360 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7361 <file>/var/log/lastlog</file> must be installed writeable by
7362 group <tt>utmp</tt>. Programs which need to modify those
7363 files must be installed setgid <tt>utmp</tt>.
7368 <heading>Editors and pagers</heading>
7371 Some programs have the ability to launch an editor or pager
7372 program to edit or display a text document. Since there are
7373 lots of different editors and pagers available in the Debian
7374 distribution, the system administrator and each user should
7375 have the possibility to choose their preferred editor and
7380 In addition, every program should choose a good default
7381 editor/pager if none is selected by the user or system
7386 Thus, every program that launches an editor or pager must
7387 use the EDITOR or PAGER environment variable to determine
7388 the editor or pager the user wishes to use. If these
7389 variables are not set, the programs <file>/usr/bin/editor</file>
7390 and <file>/usr/bin/pager</file> should be used, respectively.
7394 These two files are managed through the <prgn>dpkg</prgn>
7395 "alternatives" mechanism. Thus every package providing an
7396 editor or pager must call the
7397 <prgn>update-alternatives</prgn> script to register these
7402 If it is very hard to adapt a program to make use of the
7403 EDITOR or PAGER variables, that program may be configured to
7404 use <file>/usr/bin/sensible-editor</file> and
7405 <file>/usr/bin/sensible-pager</file> as the editor or pager
7406 program respectively. These are two scripts provided in the
7407 Debian base system that check the EDITOR and PAGER variables
7408 and launch the appropriate program, and fall back to
7409 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7410 variable is not set.
7414 A program may also use the VISUAL environment variable to
7415 determine the user's choice of editor. If it exists, it
7416 should take precedence over EDITOR. This is in fact what
7417 <file>/usr/bin/sensible-editor</file> does.
7421 It is not required for a package to depend on
7422 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7423 package to provide such virtual packages.<footnote>
7424 The Debian base system already provides an editor and a
7430 <sect id="web-appl">
7431 <heading>Web servers and applications</heading>
7434 This section describes the locations and URLs that should
7435 be used by all web servers and web applications in the
7442 Cgi-bin executable files are installed in the
7444 <example compact="compact">
7445 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7447 and should be referred to as
7448 <example compact="compact">
7449 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7454 <p>Access to HTML documents</p>
7457 HTML documents for a package are stored in
7458 <file>/usr/share/doc/<var>package</var></file>
7459 and can be referred to as
7460 <example compact="compact">
7461 http://localhost/doc/<var>package</var>/<var>filename</var>
7466 The web server should restrict access to the document
7467 tree so that only clients on the same host can read
7468 the documents. If the web server does not support such
7469 access controls, then it should not provide access at
7470 all, or ask about providing access during installation.
7475 <p>Web Document Root</p>
7478 Web Applications should try to avoid storing files in
7479 the Web Document Root. Instead they should use the
7480 /usr/share/doc/<var>package</var> directory for
7481 documents and register the Web Application via the
7482 <package>doc-base</package> package. If access to the
7483 web document root is unavoidable then use
7484 <example compact="compact">
7487 as the Document Root. This might be just a symbolic
7488 link to the location where the system administrator
7489 has put the real document root.
7497 <sect id="mail-transport-agents">
7498 <heading>Mail transport, delivery and user agents</heading>
7501 Debian packages which process electronic mail, whether mail
7502 user agents (MUAs) or mail transport agents (MTAs), must
7503 ensure that they are compatible with the configuration
7504 decisions below. Failure to do this may result in lost
7505 mail, broken <tt>From:</tt> lines, and other serious brain
7510 The mail spool is <file>/var/mail</file> and the interface to
7511 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7512 the FHS). On older systems, the mail spool may be
7513 physically located in <file>/var/spool/mail</file>, but all
7514 access to the mail spool should be via the
7515 <file>/var/mail</file> symlink. The mail spool is part of the
7516 base system and not part of the MTA package.
7520 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7521 programs (such as IMAP daemons) must lock the mailbox in an
7522 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7523 be combined with dot locking. To avoid deadlocks, a program
7524 should use <tt>fcntl()</tt> first and dot locking after
7525 this, or alternatively implement the two locking methods in
7526 a non blocking way<footnote>
7527 If it is not possible to establish both locks, the
7528 system shouldn't wait for the second lock to be
7529 established, but remove the first lock, wait a (random)
7530 time, and start over locking again.
7531 </footnote>. Using the functions <tt>maillock</tt> and
7532 <tt>mailunlock</tt> provided by the
7533 <tt>liblockfile*</tt><footnote>
7534 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7535 to use these functions.
7536 </footnote> packages is the recommended way to realize this.
7540 Mailboxes are generally mode 660
7541 <tt><var>user</var>.mail</tt> unless the system
7542 administrator has chosen otherwise. A MUA may remove a
7543 mailbox (unless it has nonstandard permissions) in which
7544 case the MTA or another MUA must recreate it if needed.
7545 Mailboxes must be writable by group mail.
7549 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7550 be setgid mail to do the locking mentioned above (and
7551 must obviously avoid accessing other users' mailboxes
7552 using this privilege).</p>
7555 <file>/etc/aliases</file> is the source file for the system mail
7556 aliases (e.g., postmaster, usenet, etc.), it is the one
7557 which the sysadmin and <prgn>postinst</prgn> scripts may
7558 edit. After <file>/etc/aliases</file> is edited the program or
7559 human editing it must call <prgn>newaliases</prgn>. All MTA
7560 packages must come with a <prgn>newaliases</prgn> program,
7561 even if it does nothing, but older MTA packages did not do
7562 this so programs should not fail if <prgn>newaliases</prgn>
7563 cannot be found. Note that because of this, all MTA
7564 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7565 <tt>Replaces: mail-transport-agent</tt> control file
7570 The convention of writing <tt>forward to
7571 <var>address</var></tt> in the mailbox itself is not
7572 supported. Use a <tt>.forward</tt> file instead.</p>
7575 The <prgn>rmail</prgn> program used by UUCP
7576 for incoming mail should be <file>/usr/sbin/rmail</file>.
7577 Likewise, <prgn>rsmtp</prgn>, for receiving
7578 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7582 If your package needs to know what hostname to use on (for
7583 example) outgoing news and mail messages which are generated
7584 locally, you should use the file <file>/etc/mailname</file>. It
7585 will contain the portion after the username and <tt>@</tt>
7586 (at) sign for email addresses of users on the machine
7587 (followed by a newline).
7591 Such package should check for the existence of this file
7592 when it is being configured. If it exists, it should be
7593 used without comment, although an MTA's configuration script
7594 may wish to prompt the user even if it finds that this file
7595 exists. If the file does not exist, the package should
7596 prompt the user for the value (preferably using
7597 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7598 as well as using it in the package's configuration. The
7599 prompt should make it clear that the name will not just be
7600 used by that package. For example, in this situation the
7601 <tt>inn</tt> package could say something like:
7602 <example compact="compact">
7603 Please enter the "mail name" of your system. This is the
7604 hostname portion of the address to be shown on outgoing
7605 news and mail messages. The default is
7606 <var>syshostname</var>, your system's host name. Mail
7607 name ["<var>syshostname</var>"]:
7609 where <var>syshostname</var> is the output of <tt>hostname
7615 <heading>News system configuration</heading>
7618 All the configuration files related to the NNTP (news)
7619 servers and clients should be located under
7620 <file>/etc/news</file>.</p>
7623 There are some configuration issues that apply to a number
7624 of news clients and server packages on the machine. These
7628 <tag><file>/etc/news/organization</file></tag>
7630 A string which should appear as the
7631 organization header for all messages posted
7632 by NNTP clients on the machine
7635 <tag><file>/etc/news/server</file></tag>
7637 Contains the FQDN of the upstream NNTP
7638 server, or localhost if the local machine is
7643 Other global files may be added as required for cross-package news
7650 <heading>Programs for the X Window System</heading>
7653 <heading>Providing X support and package priorities</heading>
7656 Programs that can be configured with support for the X
7657 Window System must be configured to do so and must declare
7658 any package dependencies necessary to satisfy their
7659 runtime requirements when using the X Window System. If
7660 such a package is of higher priority than the X packages
7661 on which it depends, it is required that either the
7662 X-specific components be split into a separate package, or
7663 that an alternative version of the package, which includes
7664 X support, be provided, or that the package's priority be
7670 <heading>Packages providing an X server</heading>
7673 Packages that provide an X server that, directly or
7674 indirectly, communicates with real input and display
7675 hardware should declare in their control data that they
7676 provide the virtual package <tt>xserver</tt>.<footnote>
7677 This implements current practice, and provides an
7678 actual policy for usage of the <tt>xserver</tt>
7679 virtual package which appears in the virtual packages
7680 list. In a nutshell, X servers that interface
7681 directly with the display and input hardware or via
7682 another subsystem (e.g., GGI) should provide
7683 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7684 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7690 <heading>Packages providing a terminal emulator</heading>
7693 Packages that provide a terminal emulator for the X Window
7694 System which meet the criteria listed below should declare
7695 in their control data that they provide the virtual
7696 package <tt>x-terminal-emulator</tt>. They should also
7697 register themselves as an alternative for
7698 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7703 To be an <tt>x-terminal-emulator</tt>, a program must:
7704 <list compact="compact">
7706 Be able to emulate a DEC VT100 terminal, or a
7707 compatible terminal.
7711 Support the command-line option <tt>-e
7712 <var>command</var></tt>, which creates a new
7713 terminal window<footnote>
7714 "New terminal window" does not necessarily mean
7715 a new top-level X window directly parented by
7716 the window manager; it could, if the terminal
7717 emulator application were so coded, be a new
7718 "view" in a multiple-document interface (MDI).
7720 and runs the specified <var>command</var>,
7721 interpreting the entirity of the rest of the command
7722 line as a command to pass straight to exec, in the
7723 manner that <tt>xterm</tt> does.
7727 Support the command-line option <tt>-T
7728 <var>title</var></tt>, which creates a new terminal
7729 window with the window title <var>title</var>.
7736 <heading>Packages providing a window manager</heading>
7739 Packages that provide a window manager should declare in
7740 their control data that they provide the virtual package
7741 <tt>x-window-manager</tt>. They should also register
7742 themselves as an alternative for
7743 <file>/usr/bin/x-window-manager</file>, with a priority
7744 calculated as follows:
7745 <list compact="compact">
7747 Start with a priority of 20.
7751 If the window manager supports the Debian menu
7752 system, add 20 points if this support is available
7753 in the package's default configuration (i.e., no
7754 configuration files belonging to the system or user
7755 have to be edited to activate the feature); if
7756 configuration files must be modified, add only 10
7762 If the window manager complies with <url
7763 id="http://www.freedesktop.org/Standards/wm-spec"
7764 name="The Window Manager Specification Project">,
7765 written by the <url id="http://www.freedesktop.org/"
7766 name="Free Desktop Group">, add 40 points.
7770 If the window manager permits the X session to be
7771 restarted using a <em>different</em> window manager
7772 (without killing the X server) in its default
7773 configuration, add 10 points; otherwise add none.
7780 <heading>Packages providing fonts</heading>
7783 Packages that provide fonts for the X Window
7785 For the purposes of Debian Policy, a "font for the X
7786 Window System" is one which is accessed via X protocol
7787 requests. Fonts for the Linux console, for PostScript
7788 renderers, or any other purpose, do not fit this
7789 definition. Any tool which makes such fonts available
7790 to the X Window System, however, must abide by this
7793 must do a number of things to ensure that they are both
7794 available without modification of the X or font server
7795 configuration, and that they do not corrupt files used by
7796 other font packages to register information about
7800 Fonts of any type supported by the X Window System
7801 must be in a separate binary package from any
7802 executables, libraries, or documentation (except
7803 that specific to the fonts shipped, such as their
7804 license information). If one or more of the fonts
7805 so packaged are necessary for proper operation of
7806 the package with which they are associated the font
7807 package may be Recommended; if the fonts merely
7808 provide an enhancement, a Suggests relationship may
7809 be used. Packages must not Depend on font
7811 This is because the X server may retrieve fonts
7812 from the local filesystem or over the network
7813 from an X font server; the Debian package system
7814 is empowered to deal only with the local
7820 BDF fonts must be converted to PCF fonts with the
7821 <prgn>bdftopcf</prgn> utility (available in the
7822 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7823 placed in a directory that corresponds to their
7825 <list compact="compact">
7827 100 dpi fonts must be placed in
7828 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7832 75 dpi fonts must be placed in
7833 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7837 Character-cell fonts, cursor fonts, and other
7838 low-resolution fonts must be placed in
7839 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7845 Speedo fonts must be placed in
7846 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7850 Type 1 fonts must be placed in
7851 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7852 metric files are available, they must be placed here
7857 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7858 other than those listed above must be neither
7859 created nor used. (The <file>PEX</file>, <file>CID</file>,
7860 and <file>cyrillic</file> directories are excepted for
7861 historical reasons, but installation of files into
7862 these directories remains discouraged.)
7866 Font packages may, instead of placing files directly
7867 in the X font directories listed above, provide
7868 symbolic links in that font directory pointing to
7869 the files' actual location in the filesystem. Such
7870 a location must comply with the FHS.
7874 Font packages should not contain both 75dpi and
7875 100dpi versions of a font. If both are available,
7876 they should be provided in separate binary packages
7877 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7878 the names of the packages containing the
7879 corresponding fonts.
7883 Fonts destined for the <file>misc</file> subdirectory
7884 should not be included in the same package as 75dpi
7885 or 100dpi fonts; instead, they should be provided in
7886 a separate package with <tt>-misc</tt> appended to
7891 Font packages must not provide the files
7892 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7893 <file>fonts.scale</file> in a font directory:
7896 <file>fonts.dir</file> files must not be provided at all.
7900 <file>fonts.alias</file> and <file>fonts.scale</file>
7901 files, if needed, should be provided in the
7903 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7904 where <var>fontdir</var> is the name of the
7906 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7907 package's corresponding fonts are stored
7908 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7909 <var>package</var> is the name of the package
7910 that provides these fonts, and
7911 <var>extension</var> is either <tt>scale</tt>
7912 or <tt>alias</tt>, whichever corresponds to
7919 Font packages must declare a dependency on
7920 <tt>xutils (>> 4.0.3)</tt> in their control
7925 Font packages that provide one or more
7926 <file>fonts.scale</file> files as described above must
7927 invoke <prgn>update-fonts-scale</prgn> on each
7928 directory into which they installed fonts
7929 <em>before</em> invoking
7930 <prgn>update-fonts-dir</prgn> on that directory.
7931 This invocation must occur in both the
7932 <prgn>postinst</prgn> (for all arguments) and
7933 <prgn>postrm</prgn> (for all arguments except
7934 <tt>upgrade</tt>) scripts.
7938 Font packages that provide one or more
7939 <file>fonts.alias</file> files as described above must
7940 invoke <prgn>update-fonts-alias</prgn> on each
7941 directory into which they installed fonts. This
7942 invocation must occur in both the
7943 <prgn>postinst</prgn> (for all arguments) and
7944 <prgn>postrm</prgn> (for all arguments except
7945 <tt>upgrade</tt>) scripts.
7949 Font packages must invoke
7950 <prgn>update-fonts-dir</prgn> on each directory into
7951 which they installed fonts. This invocation must
7952 occur in both the <prgn>postinst</prgn> (for all
7953 arguments) and <prgn>postrm</prgn> (for all
7954 arguments except <tt>upgrade</tt>) scripts.
7958 Font packages must not provide alias names for the
7959 fonts they include which collide with alias names
7960 already in use by fonts already packaged.
7964 Font packages must not provide fonts with the same
7965 XLFD registry name as another font already packaged.
7972 <heading>Application defaults files</heading>
7975 Application defaults files must be installed in the
7976 directory <file>/etc/X11/app-defaults/</file> (use of a
7977 localized subdirectory of <file>/etc/X11/</file> as described
7978 in the <em>X Toolkit Intrinsics - C Language
7979 Interface</em> manual is also permitted). They must be
7980 registered as <tt>conffile</tt>s or handled as
7981 configuration files. Packages must not provide the
7982 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7986 Customization of programs' X resources may also be
7987 supported with the provision of a file with the same name
7988 as that of the package placed in the
7989 <file>/etc/X11/Xresources/</file> directory, which must
7990 registered as a <tt>conffile</tt> or handled as a
7991 configuration file.<footnote>
7992 Note that this mechanism is not the same as using
7993 app-defaults; app-defaults are tied to the client
7994 binary on the local filesystem, whereas X resources
7995 are stored in the X server and affect all connecting
7998 <em>Important:</em> packages that install files into the
7999 <file>/etc/X11/Xresources/</file> directory must conflict with
8000 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
8001 it is possible for the installing package to destroy a
8002 previously-existing <file>/etc/X11/Xresources</file> file
8003 which had been customized by the system administrator.
8008 <heading>Installation directory issues</heading>
8011 Packages using the X Window System should not be
8012 configured to install files under the <file>/usr/X11R6/</file>
8013 directory unless they use <prgn>imake</prgn>. The
8014 <file>/usr/X11R6/</file> directory hierarchy should be
8015 regarded as deprecated for all packages except the X
8016 Window System itself, and those which use the
8017 <prgn>imake</prgn> program it provides, in which case the
8018 packages may transition out of the <file>/usr/X11R6/</file>
8019 directory at the maintainer's discretion.<footnote>
8020 <prgn>Imake</prgn>-using programs are exempt because,
8021 as long as they are written correctly, the pathnames
8022 they use to locate resources and install themselves
8023 are derived wholly from the X Window System
8024 configuration. Thus, in the event that the X Window
8025 System moves to <file>/usr/X11R7/</file>,
8026 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
8027 that is required for these programs is a recompile
8028 against the corresponding X Window System library
8029 development packages.
8034 Programs that use GNU <prgn>autoconf</prgn> and
8035 <prgn>automake</prgn> are usually easily configured at
8036 compile time to use <file>/usr/</file> instead of
8037 <file>/usr/X11R6/</file>, and this should be done whenever
8038 possible. Configuration files for window managers and
8039 display managers should be placed in a subdirectory of
8040 <file>/etc/X11/</file> corresponding to the package name due
8041 to these programs' tight integration with the mechanisms
8042 of the X Window System. Application-level programs should
8043 use the <file>/etc/</file> directory unless otherwise mandated
8048 The installation of files into subdirectories
8049 of <file>/usr/X11R6/include/X11/</file> and
8050 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8051 package maintainers should determine if subdirectories of
8052 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8053 instead. (The use of symbolic links from the
8054 <file>X11R6</file> directories to other FHS-compliant
8055 locations is encouraged if the program is not easily
8056 configured to look elsewhere for its files.)
8060 Packages must not provide or install files into the directories
8061 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8062 <file>/usr/lib/X11/</file>. Files within a package should,
8063 however, make reference to these directories, rather than
8064 their <tt>X11R6</tt>-named counterparts
8065 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8066 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8067 referred to have not been moved to other FHS-compliant
8073 <heading>The OSF/Motif and OpenMotif libraries</heading>
8076 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8077 OpenMotif libraries</em><footnote>
8078 OSF/Motif and OpenMotif are collectively referred to as
8079 "Motif" in this policy document.
8081 should be compiled against and tested with LessTif (a free
8082 re-implementation of Motif) instead. If the maintainer
8083 judges that the program or programs do not work
8084 sufficiently well with LessTif to be distributed and
8085 supported, but do so when compiled against Motif, then two
8086 versions of the package should be created; one linked
8087 statically against Motif and with <tt>-smotif</tt>
8088 appended to the package name, and one linked dynamically
8089 against Motif and with <tt>-dmotif</tt> appended to the
8094 Both Motif-linked versions are dependent
8095 upon non-DFSG-compliant software and thus cannot be
8096 uploaded to the <em>main</em> distribution; if the
8097 software is itself DFSG-compliant it may be uploaded to
8098 the <em>contrib</em> distribution. While known existing
8099 versions of Motif permit unlimited redistribution of
8100 binaries linked against the library (whether statically or
8101 dynamically), it is the package maintainer's
8102 responsibility to determine whether this is permitted by
8103 the license of the copy of Motif in their possession.
8109 <heading>Perl programs and modules</heading>
8112 Perl programs and modules should follow the current Perl policy.
8116 The Perl policy can be found in the <tt>perl-policy</tt>
8117 files in the <tt>debian-policy</tt> package.
8118 It is also available from the Debian web mirrors at
8119 <tt><url name="/doc/packaging-manuals/perl-policy/"
8120 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8125 <heading>Emacs lisp programs</heading>
8128 Please refer to the "Debian Emacs Policy" for details of how to
8129 package emacs lisp programs.
8133 The Emacs policy is available in
8134 <file>debian-emacs-policy.gz</file> of the
8135 <package>emacsen-common</package> package.
8136 It is also available from the Debian web mirrors at
8137 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8138 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8143 <heading>Games</heading>
8146 The permissions on <file>/var/games</file> are mode 755, owner
8147 <tt>root</tt> and group <tt>root</tt>.
8151 Each game decides on its own security policy.</p>
8154 Games which require protected, privileged access to
8155 high-score files, savegames, etc., may be made
8156 set-<em>group</em>-id (mode 2755) and owned by
8157 <tt>root.games</tt>, and use files and directories with
8158 appropriate permissions (770 <tt>root.games</tt>, for
8159 example). They must not be made
8160 set-<em>user</em>-id, as this causes security problems. (If
8161 an attacker can subvert any set-user-id game they can
8162 overwrite the executable of any other, causing other players
8163 of these games to run a Trojan horse program. With a
8164 set-group-id game the attacker only gets access to less
8165 important game data, and if they can get at the other
8166 players' accounts at all it will take considerably more
8170 Some packages, for example some fortune cookie programs, are
8171 configured by the upstream authors to install with their
8172 data files or other static information made unreadable so
8173 that they can only be accessed through set-id programs
8174 provided. You should not do this in a Debian package: anyone can
8175 download the <file>.deb</file> file and read the data from it,
8176 so there is no point making the files unreadable. Not
8177 making the files unreadable also means that you don't have
8178 to make so many programs set-id, which reduces the risk of a
8182 As described in the FHS, binaries of games should be
8183 installed in the directory <file>/usr/games</file>. This also
8184 applies to games that use the X Window System. Manual pages
8185 for games (X and non-X games) should be installed in
8186 <file>/usr/share/man/man6</file>.</p>
8192 <heading>Documentation</heading>
8195 <heading>Manual pages</heading>
8198 You should install manual pages in <prgn>nroff</prgn> source
8199 form, in appropriate places under <file>/usr/share/man</file>.
8200 You should only use sections 1 to 9 (see the FHS for more
8201 details). You must not install a preformatted "cat page".
8205 Each program, utility, and function should have an
8206 associated manual page included in the same package. It is
8207 suggested that all configuration files also have a manual
8208 page included as well. Manual pages for protocols and other
8209 auxiliary things are optional.
8213 If no manual page is available, this is considered as a bug
8214 and should be reported to the Debian Bug Tracking System (the
8215 maintainer of the package is allowed to write this bug report
8216 themselves, if they so desire). Do not close the bug report
8217 until a proper man page is available.<footnote>
8218 It is not very hard to write a man page. See the
8219 <url id="http://www.schweikhardt.net/man_page_howto.html"
8220 name="Man-Page-HOWTO">,
8221 <manref name="man" section="7">, the examples
8222 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8223 the helper programs <prgn>help2man</prgn>, or the
8224 directory <file>/usr/share/doc/man-db/examples</file>.
8229 You may forward a complaint about a missing man page to the
8230 upstream authors, and mark the bug as forwarded in the
8231 Debian bug tracking system. Even though the GNU Project do
8232 not in general consider the lack of a man page to be a bug,
8233 we do; if they tell you that they don't consider it a bug
8234 you should leave the bug in our bug tracking system open
8239 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8243 If one man page needs to be accessible via several names it
8244 is better to use a symbolic link than the <file>.so</file>
8245 feature, but there is no need to fiddle with the relevant
8246 parts of the upstream source to change from <file>.so</file> to
8247 symlinks: don't do it unless it's easy. You should not
8248 create hard links in the manual page directories, nor put
8249 absolute filenames in <file>.so</file> directives. The filename
8250 in a <file>.so</file> in a man page should be relative to the
8251 base of the man page tree (usually
8252 <file>/usr/share/man</file>). If you do not create any links
8253 (whether symlinks, hard links, or <tt>.so</tt> directives)
8254 in the filesystem to the alternate names of the man page,
8255 then you should not rely on <prgn>man</prgn> finding your
8256 man page under those names based solely on the information in
8257 the man page's header.<footnote>
8258 Supporting this in <prgn>man</prgn> often requires
8259 unreasonable processing time to find a manual page or to
8260 report that none exists, and moves knowledge into man's
8261 database that would be better left in the filesystem.
8262 This support is therefore deprecated and will cease to
8263 be present in the future.
8269 <heading>Info documents</heading>
8272 Info documents should be installed in <file>/usr/share/info</file>.
8273 They should be compressed with <tt>gzip -9</tt>.
8277 Your package should call <prgn>install-info</prgn> to update
8278 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8279 script when called with a <tt>configure</tt> argument, for
8281 <example compact="compact">
8282 install-info --quiet --section Development Development \
8283 /usr/share/info/foobar.info
8287 It is a good idea to specify a section for the location of
8288 your program; this is done with the <tt>--section</tt>
8289 switch. To determine which section to use, you should look
8290 at <file>/usr/share/info/dir</file> on your system and choose the most
8291 relevant (or create a new section if none of the current
8292 sections are relevant). Note that the <tt>--section</tt>
8293 flag takes two arguments; the first is a regular expression
8294 to match (case-insensitively) against an existing section,
8295 the second is used when creating a new one.</p>
8298 You should remove the entries in the <prgn>prerm</prgn>
8299 script when called with a <tt>remove</tt> argument:
8300 <example compact="compact">
8301 install-info --quiet --remove /usr/share/info/foobar.info
8305 If <prgn>install-info</prgn> cannot find a description entry
8306 in the Info file you must supply one. See <manref
8307 name="install-info" section="8"> for details.</p>
8311 <heading>Additional documentation</heading>
8314 Any additional documentation that comes with the package may
8315 be installed at the discretion of the package maintainer.
8316 Text documentation should be installed in the directory
8317 <file>/usr/share/doc/<var>package</var></file>, where
8318 <var>package</var> is the name of the package, and
8319 compressed with <tt>gzip -9</tt> unless it is small.
8323 If a package comes with large amounts of documentation which
8324 many users of the package will not require you should create
8325 a separate binary package to contain it, so that it does not
8326 take up disk space on the machines of users who do not need
8327 or want it installed.</p>
8330 It is often a good idea to put text information files
8331 (<file>README</file>s, changelogs, and so forth) that come with
8332 the source package in <file>/usr/share/doc/<var>package</var></file>
8333 in the binary package. However, you don't need to install
8334 the instructions for building and installing the package, of
8338 Packages must not require the existence of any files in
8339 <file>/usr/share/doc/</file> in order to function
8341 The system administrator should be able to
8342 delete files in <file>/usr/share/doc/</file> without causing
8343 any programs to break.
8345 Any files that are referenced by programs but are also
8346 useful as standalone documentation should be installed under
8347 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8348 <file>/usr/share/doc/<var>package</var></file>.
8352 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8353 link to another directory in <file>/usr/share/doc</file> only if
8354 the two packages both come from the same source and the
8355 first package Depends on the second.<footnote>
8357 Please note that this does not override the section on
8358 changelog files below, so the file
8359 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8360 must refer to the changelog for the current version of
8361 <var>package</var> in question. In practice, this means
8362 that the sources of the target and the destnation of the
8363 symlink must be the same (same source package and
8370 Former Debian releases placed all additional documentation
8371 in <file>/usr/doc/<var>package</var></file>. This has been
8372 changed to <file>/usr/share/doc/<var>package</var></file>,
8373 and packages must not put documentation in the directory
8374 <file>/usr/doc/<var>package</var></file>. <footnote>
8375 At this phase of the transition, we no longer require a
8376 symbolic link in <file>/usr/doc/</file>. At a later point,
8377 policy shall change to make the symbolic links a bug.
8383 <heading>Preferred documentation formats</heading>
8386 The unification of Debian documentation is being carried out
8390 If your package comes with extensive documentation in a
8391 markup format that can be converted to various other formats
8392 you should if possible ship HTML versions in a binary
8393 package, in the directory
8394 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8395 its subdirectories.<footnote>
8396 The rationale: The important thing here is that HTML
8397 docs should be available in <em>some</em> package, not
8398 necessarily in the main binary package.
8403 Other formats such as PostScript may be provided at the
8404 package maintainer's discretion.
8408 <sect id="copyrightfile">
8409 <heading>Copyright information</heading>
8412 Every package must be accompanied by a verbatim copy of its
8413 copyright and distribution license in the file
8414 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8415 file must neither be compressed nor be a symbolic link.
8419 In addition, the copyright file must say where the upstream
8420 sources (if any) were obtained. It should name the original
8421 authors of the package and the Debian maintainer(s) who were
8422 involved with its creation.</p>
8425 A copy of the file which will be installed in
8426 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8427 be in <file>debian/copyright</file> in the source package.
8431 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8432 link to another directory in <file>/usr/share/doc</file> only if
8433 the two packages both come from the same source and the
8434 first package Depends on the second. These rules are
8435 important because copyrights must be extractable by
8440 Packages distributed under the UCB BSD license, the Artistic
8441 license, the GNU GPL, and the GNU LGPL should refer to the
8442 files <file>/usr/share/common-licenses/BSD</file>,
8443 <file>/usr/share/common-licenses/Artistic</file>,
8444 <file>/usr/share/common-licenses/GPL</file>, and
8445 <file>/usr/share/common-licenses/LGPL</file> respectively,
8446 rather than quoting them in the copyright file.
8450 You should not use the copyright file as a general <file>README</file>
8451 file. If your package has such a file it should be
8452 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8453 <file>README.Debian</file> or some other appropriate place.</p>
8457 <heading>Examples</heading>
8460 Any examples (configurations, source files, whatever),
8461 should be installed in a directory
8462 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8463 files should not be referenced by any program: they're there
8464 for the benefit of the system administrator and users as
8465 documentation only. Architecture-specific example files
8466 should be installed in a directory
8467 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8469 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8470 latter directory itself may be a symbolic link to the
8475 If the purpose of a package is to provide examples, then the
8476 example files may be installed into
8477 <file>/usr/share/doc/<var>package</var></file>.
8481 <sect id="changelogs">
8482 <heading>Changelog files</heading>
8485 Packages that are not Debian-native must contain a
8486 compressed copy of the <file>debian/changelog</file> file from
8487 the Debian source tree in
8488 <file>/usr/share/doc/<var>package</var></file> with the name
8489 <file>changelog.Debian.gz</file>.
8493 If an upstream changelog is available, it should be accessible as
8494 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8495 plain text. If the upstream changelog is distributed in
8496 HTML, it should be made available in that form as
8497 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8498 and a plain text <file>changelog.gz</file> should be generated
8499 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8500 the upstream changelog files do not already conform to this
8501 naming convention, then this may be achieved either by
8502 renaming the files, or by adding a symbolic link, at the
8503 maintainer's discretion.<footnote>
8504 Rationale: People should not have to look in places for
8505 upstream changelogs merely because they are given
8506 different names or are distributed in HTML format.
8511 All of these files should be installed compressed using
8512 <tt>gzip -9</tt>, as they will become large with time even
8513 if they start out small.
8517 If the package has only one changelog which is used both as
8518 the Debian changelog and the upstream one because there is
8519 no separate upstream maintainer then that changelog should
8520 usually be installed as
8521 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8522 there is a separate upstream maintainer, but no upstream
8523 changelog, then the Debian changelog should still be called
8524 <file>changelog.Debian.gz</file>.
8528 For details about the format and contents of the Debian
8529 changelog file, please see <ref id="dpkgchangelog">.
8534 <appendix id="pkg-scope">
8535 <heading>Introduction and scope of these appendices</heading>
8538 These appendices are taken essentially verbatim from the
8539 now-deprecated Packaging Manual, version 3.2.1.0. They are
8540 the chapters which are likely to be of use to package
8541 maintainers and which have not already been included in the
8542 policy document itself. Most of these sections are very likely
8543 not relevant to policy; they should be treated as
8544 documentation for the packaging system. Please note that these
8545 appendices are included for convenience, and for historical
8546 reasons: they used to be part of policy package, and they have
8547 not yet been incorporated into dpkg documentation. However,
8548 they still have value, and hence they are presented here.
8552 They have not yet been checked to ensure that they are
8553 compatible with the contents of policy, and if there are any
8554 contradictions, the version in the main policy document takes
8555 precedence. The remaining chapters of the old Packaging
8556 Manual have also not been read in detail to ensure that there
8557 are not parts which have been left out. Both of these will be
8562 Certain parts of the Packaging manual were integrated into the
8563 Policy Manual proper, and removed from the appendices. Links
8564 have been placed from the old locations to the new ones.
8568 <prgn>dpkg</prgn> is a suite of programs for creating binary
8569 package files and installing and removing them on Unix
8571 <prgn>dpkg</prgn> is targetted primarily at Debian
8572 GNU/Linux, but may work on or be ported to other
8578 The binary packages are designed for the management of
8579 installed executable programs (usually compiled binaries) and
8580 their associated data, though source code examples and
8581 documentation are provided as part of some packages.</p>
8584 This manual describes the technical aspects of creating Debian
8585 binary packages (<file>.deb</file> files). It documents the
8586 behaviour of the package management programs
8587 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8588 they interact with packages.</p>
8591 It also documents the interaction between
8592 <prgn>dselect</prgn>'s core and the access method scripts it
8593 uses to actually install the selected packages, and describes
8594 how to create a new access method.</p>
8597 This manual does not go into detail about the options and
8598 usage of the package building and installation tools. It
8599 should therefore be read in conjuction with those programs'
8604 The utility programs which are provided with <prgn>dpkg</prgn>
8605 for managing various system configuration and similar issues,
8606 such as <prgn>update-rc.d</prgn> and
8607 <prgn>install-info</prgn>, are not described in detail here -
8608 please see their man pages.
8612 It is assumed that the reader is reasonably familiar with the
8613 <prgn>dpkg</prgn> System Administrators' manual.
8614 Unfortunately this manual does not yet exist.
8618 The Debian version of the FSF's GNU hello program is provided
8619 as an example for people wishing to create Debian
8620 packages. The Debian <prgn>debmake</prgn> package is
8621 recommended as a very helpful tool in creating and maintaining
8622 Debian packages. However, while the tools and examples are
8623 helpful, they do not replace the need to read and follow the
8624 Policy and Programmer's Manual.</p>
8627 <appendix id="pkg-binarypkg">
8628 <heading>Binary packages (from old Packaging Manual)</heading>
8631 The binary package has two main sections. The first part
8632 consists of various control information files and scripts used
8633 by <prgn>dpkg</prgn> when installing and removing. See <ref
8634 id="pkg-controlarea">.
8638 The second part is an archive containing the files and
8639 directories to be installed.
8643 In the future binary packages may also contain other
8644 components, such as checksums and digital signatures. The
8645 format for the archive is described in full in the
8646 <file>deb(5)</file> man page.
8650 <sect id="pkg-bincreating"><heading>Creating package files -
8651 <prgn>dpkg-deb</prgn>
8655 All manipulation of binary package files is done by
8656 <prgn>dpkg-deb</prgn>; it's the only program that has
8657 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8658 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8659 will spot that the options requested are appropriate to
8660 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8665 In order to create a binary package you must make a
8666 directory tree which contains all the files and directories
8667 you want to have in the filesystem data part of the package.
8668 In Debian-format source packages this directory is usually
8669 <file>debian/tmp</file>, relative to the top of the package's
8674 They should have the locations (relative to the root of the
8675 directory tree you're constructing) ownerships and
8676 permissions which you want them to have on the system when
8681 With current versions of <prgn>dpkg</prgn> the uid/username
8682 and gid/groupname mappings for the users and groups being
8683 used should be the same on the system where the package is
8684 built and the one where it is installed.
8688 You need to add one special directory to the root of the
8689 miniature filesystem tree you're creating:
8690 <prgn>DEBIAN</prgn>. It should contain the control
8691 information files, notably the binary package control file
8692 (see <ref id="pkg-controlfile">).
8696 The <prgn>DEBIAN</prgn> directory will not appear in the
8697 filesystem archive of the package, and so won't be installed
8698 by <prgn>dpkg</prgn> when the package is installed.
8702 When you've prepared the package, you should invoke:
8704 dpkg --build <var>directory</var>
8709 This will build the package in
8710 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8711 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8712 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8717 See the man page <manref name="dpkg-deb" section="8"> for details of how
8718 to examine the contents of this newly-created file. You may find the
8719 output of following commands enlightening:
8721 dpkg-deb --info <var>filename</var>.deb
8722 dpkg-deb --contents <var>filename</var>.deb
8723 dpkg --contents <var>filename</var>.deb
8725 To view the copyright file for a package you could use this command:
8727 dpkg --fsys-tarfile <var>filename</var>.deb | tar xO ./usr/share/doc/\*/copyright | pager
8732 <sect id="pkg-controlarea">
8733 <heading>Package control information files</heading>
8736 The control information portion of a binary package is a
8737 collection of files with names known to <prgn>dpkg</prgn>.
8738 It will treat the contents of these files specially - some
8739 of them contain information used by <prgn>dpkg</prgn> when
8740 installing or removing the package; others are scripts which
8741 the package maintainer wants <prgn>dpkg</prgn> to run.
8745 It is possible to put other files in the package control
8746 area, but this is not generally a good idea (though they
8747 will largely be ignored).
8751 Here is a brief list of the control info files supported by
8752 <prgn>dpkg</prgn> and a summary of what they're used for.
8757 <tag><tt>control</tt>
8760 This is the key description file used by
8761 <prgn>dpkg</prgn>. It specifies the package's name
8762 and version, gives its description for the user,
8763 states its relationships with other packages, and so
8764 forth. See <ref id="sourcecontrolfiles"> and
8765 <ref id="binarycontrolfiles">.
8769 It is usually generated automatically from information
8770 in the source package by the
8771 <prgn>dpkg-gencontrol</prgn> program, and with
8772 assistance from <prgn>dpkg-shlibdeps</prgn>.
8773 See <ref id="pkg-sourcetools">.
8777 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8782 These are exectuable files (usually scripts) which
8783 <prgn>dpkg</prgn> runs during installation, upgrade
8784 and removal of packages. They allow the package to
8785 deal with matters which are particular to that package
8786 or require more complicated processing than that
8787 provided by <prgn>dpkg</prgn>. Details of when and
8788 how they are called are in <ref id="maintainerscripts">.
8792 It is very important to make these scripts idempotent.
8793 See <ref id="idempotency">.
8797 The maintainer scripts are guaranteed to run with a
8798 controlling terminal and can interact with the user.
8799 See <ref id="controllingterminal">.
8803 <tag><tt>conffiles</tt>
8806 This file contains a list of configuration files which
8807 are to be handled automatically by <prgn>dpkg</prgn>
8808 (see <ref id="pkg-conffiles">). Note that not necessarily
8809 every configuration file should be listed here.
8812 <tag><tt>shlibs</tt>
8815 This file contains a list of the shared libraries
8816 supplied by the package, with dependency details for
8817 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8818 when it determines what dependencies are required in a
8819 package control file. The <tt>shlibs</tt> file format
8820 is described on <ref id="shlibs">.
8825 <sect id="pkg-controlfile">
8826 <heading>The main control information file: <tt>control</tt></heading>
8829 The most important control information file used by
8830 <prgn>dpkg</prgn> when it installs a package is
8831 <tt>control</tt>. It contains all the package's "vital
8836 The binary package control files of packages built from
8837 Debian sources are made by a special tool,
8838 <prgn>dpkg-gencontrol</prgn>, which reads
8839 <file>debian/control</file> and <file>debian/changelog</file> to
8840 find the information it needs. See <ref id="pkg-sourcepkg"> for
8845 The fields in binary package control files are listed in
8846 <ref id="binarycontrolfiles">.
8850 A description of the syntax of control files and the purpose
8851 of the fields is available in <ref id="controlfields">.
8856 <heading>Time Stamps</heading>
8859 See <ref id="timestamps">.
8864 <appendix id="pkg-sourcepkg">
8865 <heading>Source packages (from old Packaging Manual) </heading>
8868 The Debian binary packages in the distribution are generated
8869 from Debian sources, which are in a special format to assist
8870 the easy and automatic building of binaries.
8873 <sect id="pkg-sourcetools">
8874 <heading>Tools for processing source packages</heading>
8877 Various tools are provided for manipulating source packages;
8878 they pack and unpack sources and help build of binary
8879 packages and help manage the distribution of new versions.
8883 They are introduced and typical uses described here; see
8884 <manref name="dpkg-source" section="1"> for full
8885 documentation about their arguments and operation.
8889 For examples of how to construct a Debian source package,
8890 and how to use those utilities that are used by Debian
8891 source packages, please see the <prgn>hello</prgn> example
8895 <sect1 id="pkg-dpkg-source">
8897 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8902 This program is frequently used by hand, and is also
8903 called from package-independent automated building scripts
8904 such as <prgn>dpkg-buildpackage</prgn>.
8908 To unpack a package it is typically invoked with
8910 dpkg-source -x <var>.../path/to/filename</var>.dsc
8915 with the <file><var>filename</var>.tar.gz</file> and
8916 <file><var>filename</var>.diff.gz</file> (if applicable) in
8917 the same directory. It unpacks into
8918 <file><var>package</var>-<var>version</var></file>, and if
8920 <file><var>package</var>-<var>version</var>.orig</file>, in
8921 the current directory.
8925 To create a packed source archive it is typically invoked:
8927 dpkg-source -b <var>package</var>-<var>version</var>
8932 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8933 <file>.diff.gz</file> (if appropriate) in the current
8934 directory. <prgn>dpkg-source</prgn> does not clean the
8935 source tree first - this must be done separately if it is
8940 See also <ref id="pkg-sourcearchives">.</p>
8944 <sect1 id="pkg-dpkg-buildpackage">
8946 <prgn>dpkg-buildpackage</prgn> - overall package-building
8951 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8952 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8953 targets <tt>clean</tt>, <tt>build</tt> and
8954 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8955 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8956 source and binary package upload.
8960 It is usually invoked by hand from the top level of the
8961 built or unbuilt source directory. It may be invoked with
8962 no arguments; useful arguments include:
8963 <taglist compact="compact">
8964 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8967 Do not sign the <tt>.changes</tt> file or the
8968 source package <tt>.dsc</tt> file, respectively.</p>
8970 <tag><tt>-p<var>sign-command</var></tt></tag>
8973 Invoke <var>sign-command</var> instead of finding
8974 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8975 <var>sign-command</var> must behave just like
8976 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
8978 <tag><tt>-r<var>root-command</var></tt></tag>
8981 When root privilege is required, invoke the command
8982 <var>root-command</var>. <var>root-command</var>
8983 should invoke its first argument as a command, from
8984 the <prgn>PATH</prgn> if necessary, and pass its
8985 second and subsequent arguments to the command it
8986 calls. If no <var>root-command</var> is supplied
8987 then <var>dpkg-buildpackage</var> will take no
8988 special action to gain root privilege, so that for
8989 most packages it will have to be invoked as root to
8992 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8995 Two types of binary-only build and upload - see
8996 <manref name="dpkg-source" section="1">.
9003 <sect1 id="pkg-dpkg-gencontrol">
9005 <prgn>dpkg-gencontrol</prgn> - generates binary package
9010 This program is usually called from <file>debian/rules</file>
9011 (see <ref id="pkg-sourcetree">) in the top level of the source
9016 This is usually done just before the files and directories in the
9017 temporary directory tree where the package is being built have their
9018 permissions and ownerships set and the package is constructed using
9019 <prgn>dpkg-deb/</prgn>
9021 This is so that the control file which is produced has
9022 the right permissions
9027 <prgn>dpkg-gencontrol</prgn> must be called after all the
9028 files which are to go into the package have been placed in
9029 the temporary build directory, so that its calculation of
9030 the installed size of a package is correct.
9034 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9035 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9036 variable substitutions created by
9037 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9042 For a package which generates only one binary package, and
9043 which builds it in <file>debian/tmp</file> relative to the top
9044 of the source package, it is usually sufficient to call
9045 <prgn>dpkg-gencontrol</prgn>.
9049 Sources which build several binaries will typically need
9052 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9053 </example> The <tt>-P</tt> tells
9054 <prgn>dpkg-gencontrol</prgn> that the package is being
9055 built in a non-default directory, and the <tt>-p</tt>
9056 tells it which package's control file should be generated.
9060 <prgn>dpkg-gencontrol</prgn> also adds information to the
9061 list of files in <file>debian/files</file>, for the benefit of
9062 (for example) a future invocation of
9063 <prgn>dpkg-genchanges</prgn>.</p>
9066 <sect1 id="pkg-dpkg-shlibdeps">
9068 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9073 This program is usually called from <file>debian/rules</file>
9074 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9075 id="pkg-sourcetree">), in the top level of the source tree.
9079 Its arguments are executables.
9082 In a forthcoming dpkg version,
9083 <prgn>dpkg-shlibdeps</prgn> would be required to be
9084 called on shared libraries as well.
9087 They may be specified either in the locations in the
9088 source tree where they are created or in the locations
9089 in the temporary build tree where they are installed
9090 prior to binary package creation.
9092 </footnote> for which shared library dependencies should
9093 be included in the binary package's control file.
9097 If some of the found shared libraries should only
9098 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9099 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9100 by using the <tt>-d<var>dependency-field</var></tt> option
9101 before those executable(s). (Each <tt>-d</tt> option
9102 takes effect until the next <tt>-d</tt>.)
9106 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9107 output control file to be modified. Instead by default it
9108 adds to the <file>debian/substvars</file> file variable
9109 settings like <tt>shlibs:Depends</tt>. These variable
9110 settings must be referenced in dependency fields in the
9111 appropriate per-binary-package sections of the source
9116 For example, a package that generates an essential part
9117 which requires dependencies, and optional parts that
9118 which only require a recommendation, would separate those
9119 two sets of dependencies into two different fields.<footnote>
9120 At the time of writing, an example for this was the
9121 <package/xmms/ package, with Depends used for the xmms
9122 executable, Recommends for the plug-ins and Suggests for
9123 even more optional features provided by unzip.
9125 It can say in its <file>debian/rules</file>:
9127 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9128 -dRecommends <var>optionalpart anotheroptionalpart</var>
9130 and then in its main control file <file>debian/control</file>:
9133 Depends: ${shlibs:Pre-Depends}
9134 Recommends: ${shlibs:Recommends}
9140 Sources which produce several binary packages with
9141 different shared library dependency requirements can use
9142 the <tt>-p<var>varnameprefix</var></tt> option to override
9143 the default <tt>shlibs:</tt> prefix (one invocation of
9144 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9145 They can thus produce several sets of dependency
9146 variables, each of the form
9147 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9148 which can be referred to in the appropriate parts of the
9149 binary package control files.
9154 <sect1 id="pkg-dpkg-distaddfile">
9156 <prgn>dpkg-distaddfile</prgn> - adds a file to
9157 <file>debian/files</file>
9161 Some packages' uploads need to include files other than
9162 the source and binary package files.
9166 <prgn>dpkg-distaddfile</prgn> adds a file to the
9167 <file>debian/files</file> file so that it will be included in
9168 the <file>.changes</file> file when
9169 <prgn>dpkg-genchanges</prgn> is run.
9173 It is usually invoked from the <tt>binary</tt> target of
9174 <file>debian/rules</file>:
9176 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9178 The <var>filename</var> is relative to the directory where
9179 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9180 is usually the directory above the top level of the source
9181 tree. The <file>debian/rules</file> target should put the
9182 file there just before or just after calling
9183 <prgn>dpkg-distaddfile</prgn>.
9187 The <var>section</var> and <var>priority</var> are passed
9188 unchanged into the resulting <file>.changes</file> file.
9193 <sect1 id="pkg-dpkg-genchanges">
9195 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9200 This program is usually called by package-independent
9201 automatic building scripts such as
9202 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9207 It is usually called in the top level of a built source
9208 tree, and when invoked with no arguments will print out a
9209 straightforward <file>.changes</file> file based on the
9210 information in the source package's changelog and control
9211 file and the binary and source packages which should have
9217 <sect1 id="pkg-dpkg-parsechangelog">
9219 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9220 representation of a changelog
9224 This program is used internally by
9225 <prgn>dpkg-source</prgn> et al. It may also occasionally
9226 be useful in <file>debian/rules</file> and elsewhere. It
9227 parses a changelog, <file>debian/changelog</file> by default,
9228 and prints a control-file format representation of the
9229 information in it to standard output.
9233 <sect1 id="pkg-dpkg-architecture">
9235 <prgn>dpkg-architecture</prgn> - information about the build and
9240 This program can be used manually, but is also invoked by
9241 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9242 to set environment or make variables which specify the build and
9243 host architecture for the package building process.
9248 <sect id="pkg-sourcetree">
9249 <heading>The Debianised source tree</heading>
9252 The source archive scheme described later is intended to
9253 allow a Debianised source tree with some associated control
9254 information to be reproduced and transported easily. The
9255 Debianised source tree is a version of the original program
9256 with certain files added for the benefit of the
9257 Debianisation process, and with any other changes required
9258 made to the rest of the source code and installation
9263 The extra files created for Debian are in the subdirectory
9264 <file>debian</file> of the top level of the Debianised source
9265 tree. They are described below.
9268 <sect1 id="pkg-debianrules">
9269 <heading><file>debian/rules</file> - the main building script</heading>
9272 See <ref id="debianrules">.
9277 <sect1 id="pkg-dpkgchangelog">
9278 <heading><file>debian/changelog</file></heading>
9281 See <ref id="dpkgchangelog">.
9285 It is recommended that the entire changelog be encoded in the
9286 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9288 <url id="http://www.unicode.org/"
9289 name="Unicode">.<footnote>
9291 Support for Unicode, and specifically UTF-8, is
9292 steadily increasing among popular applications in
9293 Debian. For example, in unstable, GNOME 2 has
9294 excellent support (almost level 2) in almost all its
9295 applications; the big remaining one is gnome-terminal,
9296 of which one requires development versions in order to
9297 support UTF-8 (available in Debian experimental now if
9298 you want to play). I think that by the time sarge is
9299 released, UTF-8 support will start to hit critical
9302 I think it is fairly obvious that we need to
9303 eventually transition to UTF-8 for our package
9304 infrastructure; it is really the only sane charset in
9305 an international environment. Now, we can't switch to
9306 using UTF-8 for package control fields and the like
9307 until dpkg has better support, but one thing we can
9308 start doing today is requesting that Debian changelogs
9309 are UTF-8 encoded. At some point in time, we can start
9310 requiring them to do so.
9313 Checking for non-UTF8 characters in a changelog is
9314 trivial. Dump the file through
9315 <example>iconv -f utf-8 -t ucs-4</example>
9316 discard the output, and check the return
9317 value. If there are any characters in the stream
9318 which are invalid UTF-8 sequences, iconv will exit
9319 with an error code; and this will be the case for the
9320 vast majority of other character sets.
9325 <sect2><heading>Defining alternative changelog formats
9329 It is possible to use a different format to the standard
9330 one, by providing a parser for the format you wish to
9335 In order to have <tt>dpkg-parsechangelog</tt> run your
9336 parser, you must include a line within the last 40 lines
9337 of your file matching the Perl regular expression:
9338 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9339 parentheses should be the name of the format. For
9340 example, you might say:
9342 @@@ changelog-format: joebloggs @@@
9344 Changelog format names are non-empty strings of alphanumerics.
9348 If such a line exists then <tt>dpkg-parsechangelog</tt>
9349 will look for the parser as
9350 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9352 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9353 it is an error for it not to find it, or for it not to
9354 be an executable program. The default changelog format
9355 is <tt>dpkg</tt>, and a parser for it is provided with
9356 the <tt>dpkg</tt> package.
9360 The parser will be invoked with the changelog open on
9361 standard input at the start of the file. It should read
9362 the file (it may seek if it wishes) to determine the
9363 information required and return the parsed information
9364 to standard output in the form of a series of control
9365 fields in the standard format. By default it should
9366 return information about only the most recent version in
9367 the changelog; it should accept a
9368 <tt>-v<var>version</var></tt> option to return changes
9369 information from all versions present <em>strictly
9370 after</em> <var>version</var>, and it should then be an
9371 error for <var>version</var> not to be present in the
9377 <list compact="compact">
9378 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9379 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9380 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9381 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9382 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9383 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9384 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9389 If several versions are being returned (due to the use
9390 of <tt>-v</tt>), the urgency value should be of the
9391 highest urgency code listed at the start of any of the
9392 versions requested followed by the concatenated
9393 (space-separated) comments from all the versions
9394 requested; the maintainer, version, distribution and
9395 date should always be from the most recent version.
9399 For the format of the <tt>Changes</tt> field see
9400 <ref id="f-Changes">.
9404 If the changelog format which is being parsed always or
9405 almost always leaves a blank line between individual
9406 change notes these blank lines should be stripped out,
9407 so as to make the resulting output compact.
9411 If the changelog format does not contain date or package
9412 name information this information should be omitted from
9413 the output. The parser should not attempt to synthesise
9414 it or find it from other sources.
9418 If the changelog does not have the expected format the
9419 parser should exit with a nonzero exit status, rather
9420 than trying to muddle through and possibly generating
9425 A changelog parser may not interact with the user at
9431 <sect1 id="pkg-srcsubstvars">
9432 <heading><file>debian/substvars</file> and variable substitutions</heading>
9435 See <ref id="substvars">.
9441 <heading><file>debian/files</file></heading>
9444 See <ref id="debianfiles">.
9448 <sect1><heading><file>debian/tmp</file>
9452 This is the canonical temporary location for the
9453 construction of binary packages by the <tt>binary</tt>
9454 target. The directory <file>tmp</file> serves as the root of
9455 the filesystem tree as it is being constructed (for
9456 example, by using the package's upstream makefiles install
9457 targets and redirecting the output there), and it also
9458 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9459 id="pkg-bincreating">.
9463 If several binary packages are generated from the same
9464 source tree it is usual to use several
9465 <file>debian/tmp<var>something</var></file> directories, for
9466 example <file>tmp-a</file> or <file>tmp-doc</file>.
9470 Whatever <file>tmp</file> directories are created and used by
9471 <tt>binary</tt> must of course be removed by the
9472 <tt>clean</tt> target.</p></sect1>
9476 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9480 As it exists on the FTP site, a Debian source package
9481 consists of three related files. You must have the right
9482 versions of all three to be able to use them.
9487 <tag>Debian source control file - <tt>.dsc</tt></tag>
9489 This file is a control file used by <prgn>dpkg-source</prgn>
9490 to extract a source package.
9491 See <ref id="debiansourcecontrolfiles">.
9495 Original source archive -
9497 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9503 This is a compressed (with <tt>gzip -9</tt>)
9504 <prgn>tar</prgn> file containing the source code from
9505 the upstream authors of the program.
9510 Debianisation diff -
9512 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9518 This is a unified context diff (<tt>diff -u</tt>)
9519 giving the changes which are required to turn the
9520 original source into the Debian source. These changes
9521 may only include editing and creating plain files.
9522 The permissions of files, the targets of symbolic
9523 links and the characteristics of special files or
9524 pipes may not be changed and no files may be removed
9529 All the directories in the diff must exist, except the
9530 <file>debian</file> subdirectory of the top of the source
9531 tree, which will be created by
9532 <prgn>dpkg-source</prgn> if necessary when unpacking.
9536 The <prgn>dpkg-source</prgn> program will
9537 automatically make the <file>debian/rules</file> file
9538 executable (see below).</p></item>
9543 If there is no original source code - for example, if the
9544 package is specially prepared for Debian or the Debian
9545 maintainer is the same as the upstream maintainer - the
9546 format is slightly different: then there is no diff, and the
9548 <file><var>package</var>_<var>version</var>.tar.gz</file>,
9549 and preferably contains a directory named
9550 <file><var>package</var>-<var>version</var></file>.
9555 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9558 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9559 Debian source package. However, if it is not available it
9560 is possible to unpack a Debian source archive as follows:
9561 <enumlist compact="compact">
9564 Untar the tarfile, which will create a <file>.orig</file>
9568 <p>Rename the <file>.orig</file> directory to
9569 <file><var>package</var>-<var>version</var></file>.</p>
9573 Create the subdirectory <file>debian</file> at the top of
9574 the source tree.</p>
9576 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9578 <item><p>Untar the tarfile again if you want a copy of the original
9579 source code alongside the Debianised version.</p>
9584 It is not possible to generate a valid Debian source archive
9585 without using <prgn>dpkg-source</prgn>. In particular,
9586 attempting to use <prgn>diff</prgn> directly to generate the
9587 <file>.diff.gz</file> file will not work.
9591 <heading>Restrictions on objects in source packages</heading>
9594 The source package may not contain any hard links
9596 This is not currently detected when building source
9597 packages, but only when extracting
9601 Hard links may be permitted at some point in the
9602 future, but would require a fair amount of
9604 </footnote>, device special files, sockets or setuid or
9607 Setgid directories are allowed.
9612 The source packaging tools manage the changes between the
9613 original and Debianised source using <prgn>diff</prgn> and
9614 <prgn>patch</prgn>. Turning the original source tree as
9615 included in the <file>.orig.tar.gz</file> into the debianised
9616 source must not involve any changes which cannot be
9617 handled by these tools. Problematic changes which cause
9618 <prgn>dpkg-source</prgn> to halt with an error when
9619 building the source package are:
9620 <list compact="compact">
9621 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9623 <item><p>Changing the targets of symbolic links.</p>
9625 <item><p>Creating directories, other than <file>debian</file>.</p>
9627 <item><p>Changes to the contents of binary files.</p></item>
9628 </list> Changes which cause <prgn>dpkg-source</prgn> to
9629 print a warning but continue anyway are:
9630 <list compact="compact">
9633 Removing files, directories or symlinks.
9635 Renaming a file is not treated specially - it is
9636 seen as the removal of the old file (which
9637 generates a warning, but is otherwise ignored),
9638 and the creation of the new one.
9644 Changed text files which are missing the usual final
9645 newline (either in the original or the modified
9650 Changes which are not represented, but which are not detected by
9651 <prgn>dpkg-source</prgn>, are:
9652 <list compact="compact">
9653 <item><p>Changing the permissions of files (other than
9654 <file>debian/rules</file>) and directories.</p></item>
9659 The <file>debian</file> directory and <file>debian/rules</file>
9660 are handled specially by <prgn>dpkg-source</prgn> - before
9661 applying the changes it will create the <file>debian</file>
9662 directory, and afterwards it will make
9663 <file>debian/rules</file> world-exectuable.
9669 <appendix id="pkg-controlfields">
9670 <heading>Control files and their fields (from old Packaging Manual)</heading>
9673 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9674 data in a common format, known as control files. Binary and
9675 source packages have control data as do the <file>.changes</file>
9676 files which control the installation of uploaded files, and
9677 <prgn>dpkg</prgn>'s internal databases are in a similar
9682 <heading>Syntax of control files</heading>
9685 See <ref id="controlsyntax">.
9689 It is important to note that there are several fields which
9690 are optional as far as <prgn>dpkg</prgn> and the related
9691 tools are concerned, but which must appear in every Debian
9692 package, or whose omission may cause problems.
9697 <heading>List of fields</heading>
9700 See <ref id="controlfieldslist">.
9704 This section now contains only the fields that didn't belong
9705 to the Policy manual.
9708 <sect1 id="pkg-f-Filename">
9709 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9712 These fields in <tt>Packages</tt> files give the
9713 filename(s) of (the parts of) a package in the
9714 distribution directories, relative to the root of the
9715 Debian hierarchy. If the package has been split into
9716 several parts the parts are all listed in order, separated
9721 <sect1 id="pkg-f-Size">
9722 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9725 These fields in <file>Packages</file> files give the size (in
9726 bytes, expressed in decimal) and MD5 checksum of the
9727 file(s) which make(s) up a binary package in the
9728 distribution. If the package is split into several parts
9729 the values for the parts are listed in order, separated by
9734 <sect1 id="pkg-f-Status">
9735 <heading><tt>Status</tt></heading>
9738 This field in <prgn>dpkg</prgn>'s status file records
9739 whether the user wants a package installed, removed or
9740 left alone, whether it is broken (requiring
9741 reinstallation) or not and what its current state on the
9742 system is. Each of these pieces of information is a
9747 <sect1 id="pkg-f-Config-Version">
9748 <heading><tt>Config-Version</tt></heading>
9751 If a package is not installed or not configured, this
9752 field in <prgn>dpkg</prgn>'s status file records the last
9753 version of the package which was successfully
9758 <sect1 id="pkg-f-Conffiles">
9759 <heading><tt>Conffiles</tt></heading>
9762 This field in <prgn>dpkg</prgn>'s status file contains
9763 information about the automatically-managed configuration
9764 files held by a package. This field should <em>not</em>
9765 appear anywhere in a package!
9770 <heading>Obsolete fields</heading>
9773 These are still recognised by <prgn>dpkg</prgn> but should
9774 not appear anywhere any more.
9776 <taglist compact="compact">
9778 <tag><tt>Revision</tt></tag>
9779 <tag><tt>Package-Revision</tt></tag>
9780 <tag><tt>Package_Revision</tt></tag>
9782 The Debian revision part of the package version was
9783 at one point in a separate control file field. This
9784 field went through several names.
9787 <tag><tt>Recommended</tt></tag>
9788 <item>Old name for <tt>Recommends</tt>.</item>
9790 <tag><tt>Optional</tt></tag>
9791 <item>Old name for <tt>Suggests</tt>.</item>
9793 <tag><tt>Class</tt></tag>
9794 <item>Old name for <tt>Priority</tt>.</item>
9803 <appendix id="pkg-conffiles">
9804 <heading>Configuration file handling (from old Packaging Manual)</heading>
9807 <prgn>dpkg</prgn> can do a certain amount of automatic
9808 handling of package configuration files.
9812 Whether this mechanism is appropriate depends on a number of
9813 factors, but basically there are two approaches to any
9814 particular configuration file.
9818 The easy method is to ship a best-effort configuration in the
9819 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9820 handle updates. If the user is unlikely to want to edit the
9821 file, but you need them to be able to without losing their
9822 changes, and a new package with a changed version of the file
9823 is only released infrequently, this is a good approach.
9827 The hard method is to build the configuration file from
9828 scratch in the <prgn>postinst</prgn> script, and to take the
9829 responsibility for fixing any mistakes made in earlier
9830 versions of the package automatically. This will be
9831 appropriate if the file is likely to need to be different on
9835 <sect><heading>Automatic handling of configuration files by
9840 A package may contain a control area file called
9841 <tt>conffiles</tt>. This file should be a list of filenames
9842 of configuration files needing automatic handling, separated
9843 by newlines. The filenames should be absolute pathnames,
9844 and the files referred to should actually exist in the
9849 When a package is upgraded <prgn>dpkg</prgn> will process
9850 the configuration files during the configuration stage,
9851 shortly before it runs the package's <prgn>postinst</prgn>
9856 For each file it checks to see whether the version of the
9857 file included in the package is the same as the one that was
9858 included in the last version of the package (the one that is
9859 being upgraded from); it also compares the version currently
9860 installed on the system with the one shipped with the last
9865 If neither the user nor the package maintainer has changed
9866 the file, it is left alone. If one or the other has changed
9867 their version, then the changed version is preferred - i.e.,
9868 if the user edits their file, but the package maintainer
9869 doesn't ship a different version, the user's changes will
9870 stay, silently, but if the maintainer ships a new version
9871 and the user hasn't edited it the new version will be
9872 installed (with an informative message). If both have
9873 changed their version the user is prompted about the problem
9874 and must resolve the differences themselves.
9878 The comparisons are done by calculating the MD5 message
9879 digests of the files, and storing the MD5 of the file as it
9880 was included in the most recent version of the package.
9884 When a package is installed for the first time
9885 <prgn>dpkg</prgn> will install the file that comes with it,
9886 unless that would mean overwriting a file already on the
9891 However, note that <prgn>dpkg</prgn> will <em>not</em>
9892 replace a conffile that was removed by the user (or by a
9893 script). This is necessary because with some programs a
9894 missing file produces an effect hard or impossible to
9895 achieve in another way, so that a missing file needs to be
9896 kept that way if the user did it.
9900 Note that a package should <em>not</em> modify a
9901 <prgn>dpkg</prgn>-handled conffile in its maintainer
9902 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9903 the user confusing and possibly dangerous options for
9904 conffile update when the package is upgraded.</p>
9907 <sect><heading>Fully-featured maintainer script configuration
9912 For files which contain site-specific information such as
9913 the hostname and networking details and so forth, it is
9914 better to create the file in the package's
9915 <prgn>postinst</prgn> script.
9919 This will typically involve examining the state of the rest
9920 of the system to determine values and other information, and
9921 may involve prompting the user for some information which
9922 can't be obtained some other way.
9926 When using this method there are a couple of important
9927 issues which should be considered:
9931 If you discover a bug in the program which generates the
9932 configuration file, or if the format of the file changes
9933 from one version to the next, you will have to arrange for
9934 the postinst script to do something sensible - usually this
9935 will mean editing the installed configuration file to remove
9936 the problem or change the syntax. You will have to do this
9937 very carefully, since the user may have changed the file,
9938 perhaps to fix the very problem that your script is trying
9939 to deal with - you will have to detect these situations and
9940 deal with them correctly.
9944 If you do go down this route it's probably a good idea to
9945 make the program that generates the configuration file(s) a
9946 separate program in <file>/usr/sbin</file>, by convention called
9947 <file><var>package</var>config</file> and then run that if
9948 appropriate from the post-installation script. The
9949 <tt><var>package</var>config</tt> program should not
9950 unquestioningly overwrite an existing configuration - if its
9951 mode of operation is geared towards setting up a package for
9952 the first time (rather than any arbitrary reconfiguration
9953 later) you should have it check whether the configuration
9954 already exists, and require a <tt>--force</tt> flag to
9955 overwrite it.</p></sect>
9958 <appendix id="pkg-alternatives"><heading>Alternative versions of
9959 an interface - <prgn>update-alternatives</prgn> (from old
9964 When several packages all provide different versions of the
9965 same program or file it is useful to have the system select a
9966 default, but to allow the system administrator to change it
9967 and have their decisions respected.
9971 For example, there are several versions of the <prgn>vi</prgn>
9972 editor, and there is no reason to prevent all of them from
9973 being installed at once, each under their own name
9974 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9975 Nevertheless it is desirable to have the name <tt>vi</tt>
9976 refer to something, at least by default.
9980 If all the packages involved cooperate, this can be done with
9981 <prgn>update-alternatives</prgn>.
9985 Each package provides its own version under its own name, and
9986 calls <prgn>update-alternatives</prgn> in its postinst to
9987 register its version (and again in its prerm to deregister
9992 See the man page <manref name="update-alternatives"
9993 section="8"> for details.
9997 If <prgn>update-alternatives</prgn> does not seem appropriate
9998 you may wish to consider using diversions instead.</p>
10001 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10002 package's version of a file (from old Packaging Manual)
10006 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10007 when it reinstalls the package it belongs to, and to have it
10008 put the file from the package somewhere else instead.
10012 This can be used locally to override a package's version of a
10013 file, or by one package to override another's version (or
10014 provide a wrapper for it).
10018 Before deciding to use a diversion, read <ref
10019 id="pkg-alternatives"> to see if you really want a diversion
10020 rather than several alternative versions of a program.
10024 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10025 and updated by a special program <prgn>dpkg-divert</prgn>.
10026 Please see <manref name="dpkg-divert" section="8"> for full
10027 details of its operation.
10031 When a package wishes to divert a file from another, it should
10032 call <prgn>dpkg-divert</prgn> in its preinst to add the
10033 diversion and rename the existing file. For example,
10034 supposing that a <prgn>smailwrapper</prgn> package wishes to
10035 install a wrapper around <file>/usr/sbin/smail</file>:
10037 if [ install = "$1" ]; then
10038 dpkg-divert --package smailwrapper --add --rename \
10039 --divert /usr/sbin/smail.real /usr/sbin/smail
10041 </example> Testing <tt>$1</tt> is necessary so that the script
10042 doesn't try to add the diversion again when
10043 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10044 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10045 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10046 get installed as the true version.
10050 The postrm has to do the reverse:
10052 if [ remove = "$1" ]; then
10053 dpkg-divert --package smailwrapper --remove --rename \
10054 --divert /usr/sbin/smail.real /usr/sbin/smail
10060 Do not attempt to divert a file which is vitally important for
10061 the system's operation - when using <prgn>dpkg-divert</prgn>
10062 there is a time, after it has been diverted but before
10063 <prgn>dpkg</prgn> has installed the new version, when the file
10064 does not exist.</p>
10069 <!-- vim:set ai et sts=2 sw=2 tw=76: -->