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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>.<footnote>
1501 Mistakes in changelogs are usually best rectified by
1502 making a new changelog entry rather than "rewriting
1503 history" by editing old changelog entries.
1506 This includes modifications
1507 made in the Debian package compared to the upstream one
1508 as well as other changes and updates to the package.
1510 Although there is nothing stopping an author who is also
1511 the Debian maintainer from using this changelog for all
1512 their changes, it will have to be renamed if the Debian
1513 and upstream maintainers become different people. In such
1514 a case, however, it might be better to maintain the package
1515 as a non-native package.
1524 The format of the <file>debian/changelog</file> allows the
1525 package building tools to discover which version of the package
1526 is being built and find out other release-specific information.
1530 That format is a series of entries like this:
1532 <example compact="compact">
1533 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1535 [optional blank line(s), stripped]
1537 * <var>change details</var>
1538 <var>more change details</var>
1540 [blank line(s), included in output of dpkg-parsechangelog]
1542 * <var>even more change details</var>
1544 [optional blank line(s), stripped]
1546 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1551 <var>package</var> and <var>version</var> are the source
1552 package name and version number.
1556 <var>distribution(s)</var> lists the distributions where
1557 this version should be installed when it is uploaded - it
1558 is copied to the <tt>Distribution</tt> field in the
1559 <file>.changes</file> file. See <ref id="f-Distribution">.
1563 <var>urgency</var> is the value for the <tt>Urgency</tt>
1564 field in the <file>.changes</file> file for the upload
1565 (see <ref id="f-Urgency">). It is not possible to specify
1566 an urgency containing commas; commas are used to separate
1567 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1568 <prgn>dpkg</prgn> changelog format (though there is
1569 currently only one useful <var>keyword</var>,
1570 <tt>urgency</tt>).<footnote>
1571 Recognised urgency values are <tt>low</tt>,
1572 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1573 They have an effect on how quickly a package will be
1574 considered for inclusion into the <tt>testing</tt>
1575 distribution, and give an indication of the importance
1576 of any fixes included in this upload.
1581 The change details may in fact be any series of lines
1582 starting with at least two spaces, but conventionally each
1583 change starts with an asterisk and a separating space and
1584 continuation lines are indented so as to bring them in
1585 line with the start of the text above. Blank lines may be
1586 used here to separate groups of changes, if desired.
1590 If this upload resolves bugs recorded in the Bug Tracking
1591 System (BTS), they may be automatically closed on the
1592 inclusion of this package into the Debian archive by
1593 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1594 in the change details.<footnote>
1595 To be precise, the string should match the following
1596 Perl regular expression:
1598 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1600 Then all of the bug numbers listed will be closed by the
1601 archive maintenance script (<prgn>katie</prgn>), or in
1602 the case of an NMU, marked as fixed.
1604 This information is conveyed via the <tt>Closes</tt> field
1605 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1609 The maintainer name and email address used in the changelog
1610 should be the details of the person uploading <em>this</em>
1611 version. They are <em>not</em> necessarily those of the
1612 usual package maintainer. The information here will be
1613 copied to the <tt>Changed-By</tt> field in the
1614 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1615 and then later used to send an acknowledgement when the
1616 upload has been installed.
1620 The <var>date</var> should be in RFC822 format<footnote>
1621 This is generated by the <prgn>822-date</prgn>
1623 </footnote>; it should include the time zone specified
1624 numerically, with the time zone name or abbreviation
1625 optionally present as a comment in parentheses.
1629 The first "title" line with the package name should start
1630 at the left hand margin; the "trailer" line with the
1631 maintainer and date details should be preceded by exactly
1632 one space. The maintainer details and the date must be
1633 separated by exactly two spaces.
1637 For more information on placement of the changelog files
1638 within binary packages, please see <ref id="changelogs">.
1641 <sect1><heading>Alternative changelog formats</heading>
1644 In non-experimental packages you must use a format for
1645 <file>debian/changelog</file> which is supported by the most
1646 recent released version of <prgn>dpkg</prgn>.
1650 It is possible to use a format different from the standard
1651 one by providing a changelog parser for the format you wish
1652 to use. The parser must have an API compatible with that
1653 expected by <prgn>dpkg-genchanges</prgn> and
1654 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1657 If there is general interest in the new format, you should
1658 contact the <package>dpkg</package> maintainer to have the
1659 parser script for it included in the <prgn>dpkg</prgn>
1660 package. (You will need to agree that the parser and its
1661 man page may be distributed under the GNU GPL, just as the rest
1662 of <prgn>dpkg</prgn> is.)
1669 <heading>Error trapping in makefiles</heading>
1672 When <prgn>make</prgn> invokes a command in a makefile
1673 (including your package's upstream makefiles and
1674 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1675 means that <prgn>sh</prgn>'s usual bad error handling
1676 properties apply: if you include a miniature script as one
1677 of the commands in your makefile you'll find that if you
1678 don't do anything about it then errors are not detected
1679 and <prgn>make</prgn> will blithely continue after
1684 Every time you put more than one shell command (this
1685 includes using a loop) in a makefile command you
1686 must make sure that errors are trapped. For
1687 simple compound commands, such as changing directory and
1688 then running a program, using <tt>&&</tt> rather
1689 than semicolon as a command separator is sufficient. For
1690 more complex commands including most loops and
1691 conditionals you should include a separate <tt>set -e</tt>
1692 command at the start of every makefile command that's
1693 actually one of these miniature shell scripts.
1697 <sect id="timestamps">
1698 <heading>Time Stamps</heading>
1700 Maintainers should preserve the modification times of the
1701 upstream source files in a package, as far as is reasonably
1703 The rationale is that there is some information conveyed
1704 by knowing the age of the file, for example, you could
1705 recognize that some documentation is very old by looking
1706 at the modification time, so it would be nice if the
1707 modification time of the upstream source would be
1713 <sect id="restrictions">
1714 <heading>Restrictions on objects in source packages</heading>
1717 The source package may not contain any hard links<footnote>
1719 This is not currently detected when building source
1720 packages, but only when extracting
1724 Hard links may be permitted at some point in the
1725 future, but would require a fair amount of
1728 </footnote>, device special files, sockets or setuid or
1729 setgid files.<footnote>
1730 Setgid directories are allowed.
1735 <sect id="debianrules">
1736 <heading>Main building script: <file>debian/rules</file></heading>
1739 This file must be an executable makefile, and contains the
1740 package-specific recipes for compiling the package and
1741 building binary package(s) from the source.
1745 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1746 so that it can be invoked by saying its name rather than
1747 invoking <prgn>make</prgn> explicitly.
1751 Since an interactive <file>debian/rules</file> script makes it
1752 impossible to auto-compile that package and also makes it
1753 hard for other people to reproduce the same binary
1754 package, all <em>required targets</em> MUST be
1755 non-interactive. At a minimum, required targets are the
1756 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1757 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1758 <em>binary-indep</em>, and <em>build</em>. It also follows
1759 that any target that these targets depend on must also be
1764 The targets are as follows (required unless stated otherwise):
1766 <tag><tt>build</tt></tag>
1769 The <tt>build</tt> target should perform all the
1770 configuration and compilation of the package.
1771 If a package has an interactive pre-build
1772 configuration routine, the Debianized source package
1773 must either be built after this has taken place (so
1774 that the binary package can be built without rerunning
1775 the configuration) or the configuration routine
1776 modified to become non-interactive. (The latter is
1777 preferable if there are architecture-specific features
1778 detected by the configuration routine.)
1782 For some packages, notably ones where the same
1783 source tree is compiled in different ways to produce
1784 two binary packages, the <tt>build</tt> target
1785 does not make much sense. For these packages it is
1786 good enough to provide two (or more) targets
1787 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1788 for each of the ways of building the package, and a
1789 <tt>build</tt> target that does nothing. The
1790 <tt>binary</tt> target will have to build the
1791 package in each of the possible ways and make the
1792 binary package out of each.
1796 The <tt>build</tt> target must not do anything
1797 that might require root privilege.
1801 The <tt>build</tt> target may need to run the
1802 <tt>clean</tt> target first - see below.
1806 When a package has a configuration and build routine
1807 which takes a long time, or when the makefiles are
1808 poorly designed, or when <tt>build</tt> needs to
1809 run <tt>clean</tt> first, it is a good idea to
1810 <tt>touch build</tt> when the build process is
1811 complete. This will ensure that if <tt>debian/rules
1812 build</tt> is run again it will not rebuild the whole
1814 Another common way to do this is for <tt>build</tt>
1815 to depend on <prgn>build-stamp</prgn> and to do
1816 nothing else, and for the <prgn>build-stamp</prgn>
1817 target to do the building and to <tt>touch
1818 build-stamp</tt> on completion. This is
1819 especially useful if the build routine creates a
1820 file or directory called <tt>build</tt>; in such a
1821 case, <tt>build</tt> will need to be listed as
1822 a phony target (i.e., as a dependency of the
1823 <tt>.PHONY</tt> target). See the documentation of
1824 <prgn>make</prgn> for more information on phony
1830 <tag><tt>build-arch</tt> (optional),
1831 <tt>build-indep</tt> (optional)
1835 A package may also provide both of the targets
1836 <tt>build-arch</tt> and <tt>build-indep</tt>.
1837 The <tt>build-arch</tt> target, if provided, should
1838 perform all the configuration and compilation required
1839 for producing all architecture-dependant binary packages
1840 (those packages for which the body of the
1841 <tt>Architecture</tt> field in <tt>debian/control</tt>
1842 is not <tt>all</tt>).
1843 Similarly, the <tt>build-indep</tt> target, if
1844 provided, should perform all the configuration and
1845 compilation required for producing all
1846 architecture-independent binary packages
1847 (those packages for which the body of the
1848 <tt>Architecture</tt> field in <tt>debian/control</tt>
1850 The <tt>build</tt> target should depend on those of the
1851 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1852 are provided in the rules file.
1856 If one or both of the targets <tt>build-arch</tt> and
1857 <tt>build-indep</tt> are not provided, then invoking
1858 <file>debian/rules</file> with one of the not-provided
1859 targets as arguments should produce a exit status code
1860 of 2. Usually this is provided automatically by make
1861 if the target is missing.
1865 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1866 must not do anything that might require root privilege.
1870 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1871 <tt>binary-indep</tt>
1875 The <tt>binary</tt> target must be all that is
1876 necessary for the user to build the binary package(s)
1877 produced from this source package. It is
1878 split into two parts: <prgn>binary-arch</prgn> builds
1879 the binary packages which are specific to a particular
1880 architecture, and <tt>binary-indep</tt> builds
1881 those which are not.
1884 <tt>binary</tt> may be (and commonly is) a target with
1885 no commands which simply depends on
1886 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1889 Both <tt>binary-*</tt> targets should depend on the
1890 <tt>build</tt> target, or on the appropriate
1891 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1892 provided, so that the package is built if it has not
1893 been already. It should then create the relevant
1894 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1895 make their control files and <prgn>dpkg-deb</prgn> to
1896 build them and place them in the parent of the top
1901 Both the <tt>binary-arch</tt> and
1902 <tt>binary-indep</tt> targets <em>must</em> exist.
1903 If one of them has nothing to do (which will always be
1904 the case if the source generates only a single binary
1905 package, whether architecture-dependent or not), it
1906 must still exist and must always succeed.
1910 The <tt>binary</tt> targets must be invoked as
1912 The <prgn>fakeroot</prgn> package often allows one
1913 to build a package correctly even without being
1919 <tag><tt>clean</tt></tag>
1922 This must undo any effects that the <tt>build</tt>
1923 and <tt>binary</tt> targets may have had, except
1924 that it should leave alone any output files created in
1925 the parent directory by a run of a <tt>binary</tt>
1930 If a <tt>build</tt> file is touched at the end of
1931 the <tt>build</tt> target, as suggested above, it
1932 should be removed as the first action that
1933 <tt>clean</tt> performs, so that running
1934 <tt>build</tt> again after an interrupted
1935 <tt>clean</tt> doesn't think that everything is
1940 The <tt>clean</tt> target may need to be
1941 invoked as root if <tt>binary</tt> has been
1942 invoked since the last <tt>clean</tt>, or if
1943 <tt>build</tt> has been invoked as root (since
1944 <tt>build</tt> may create directories, for
1949 <tag><tt>get-orig-source</tt> (optional)</tag>
1952 This target fetches the most recent version of the
1953 original source package from a canonical archive site
1954 (via FTP or WWW, for example), does any necessary
1955 rearrangement to turn it into the original source
1956 tar file format described below, and leaves it in the
1961 This target may be invoked in any directory, and
1962 should take care to clean up any temporary files it
1967 This target is optional, but providing it if
1968 possible is a good idea.
1974 The <tt>build</tt>, <tt>binary</tt> and
1975 <tt>clean</tt> targets must be invoked with the current
1976 directory being the package's top-level directory.
1981 Additional targets may exist in <file>debian/rules</file>,
1982 either as published or undocumented interfaces or for the
1983 package's internal use.
1987 The architectures we build on and build for are determined
1988 by <prgn>make</prgn> variables using the utility
1989 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1990 You can determine the
1991 Debian architecture and the GNU style architecture
1992 specification string for the build machine (the machine type
1993 we are building on) as well as for the host machine (the
1994 machine type we are building for). Here is a list of
1995 supported <prgn>make</prgn> variables:
1996 <list compact="compact">
1998 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2001 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2002 specification string)
2005 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2006 <tt>DEB_*_GNU_TYPE</tt>)
2009 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2010 <tt>DEB_*_GNU_TYPE</tt>)
2012 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2013 the build machine or <tt>HOST</tt> for specification of the
2018 Backward compatibility can be provided in the rules file
2019 by setting the needed variables to suitable default
2020 values; please refer to the documentation of
2021 <prgn>dpkg-architecture</prgn> for details.
2025 It is important to understand that the <tt>DEB_*_ARCH</tt>
2026 string only determines which Debian architecture we are
2027 building on or for. It should not be used to get the CPU
2028 or system information; the GNU style variables should be
2033 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2034 <sect id="substvars">
2035 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2038 When <prgn>dpkg-gencontrol</prgn>,
2039 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2040 generate control files they perform variable substitutions
2041 on their output just before writing it. Variable
2042 substitutions have the form <tt>${<var>variable</var>}</tt>.
2043 The optional file <file>debian/substvars</file> contains
2044 variable substitutions to be used; variables can also be set
2045 directly from <file>debian/rules</file> using the <tt>-V</tt>
2046 option to the source packaging commands, and certain
2047 predefined variables are also available.
2051 The <file>debian/substvars</file> file is usually generated and
2052 modified dynamically by <file>debian/rules</file> targets, in
2053 which case it must be removed by the <tt>clean</tt> target.
2057 See <manref name="dpkg-source" section="1"> for full
2058 details about source variable substitutions, including the
2059 format of <file>debian/substvars</file>.</p>
2062 <sect id="debianfiles">
2063 <heading>Generated files list: <file>debian/files</file></heading>
2066 This file is not a permanent part of the source tree; it
2067 is used while building packages to record which files are
2068 being generated. <prgn>dpkg-genchanges</prgn> uses it
2069 when it generates a <file>.changes</file> file.
2073 It should not exist in a shipped source package, and so it
2074 (and any backup files or temporary files such as
2075 <file>files.new</file><footnote>
2076 <file>files.new</file> is used as a temporary file by
2077 <prgn>dpkg-gencontrol</prgn> and
2078 <prgn>dpkg-distaddfile</prgn> - they write a new
2079 version of <tt>files</tt> here before renaming it,
2080 to avoid leaving a corrupted copy if an error
2082 </footnote>) should be removed by the
2083 <tt>clean</tt> target. It may also be wise to
2084 ensure a fresh start by emptying or removing it at the
2085 start of the <tt>binary</tt> target.
2089 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2090 package, it adds an entry to <file>debian/files</file> for the
2091 <file>.deb</file> file that will be created when <tt>dpkg-deb
2092 --build</tt> is run for that binary package. So for most
2093 packages all that needs to be done with this file is to
2094 delete it in the <tt>clean</tt> target.
2098 If a package upload includes files besides the source
2099 package and any binary packages whose control files were
2100 made with <prgn>dpkg-gencontrol</prgn> then they should be
2101 placed in the parent of the package's top-level directory
2102 and <prgn>dpkg-distaddfile</prgn> should be called to add
2103 the file to the list in <file>debian/files</file>.</p>
2109 <chapt id="controlfields">
2110 <heading>Control files and their fields</heading>
2113 The package management system manipulates data represented in
2114 a common format, known as <em>control data</em>, stored in
2115 <em>control files</em>.
2116 Control files are used for source packages, binary packages and
2117 the <file>.changes</file> files which control the installation
2118 of uploaded files<footnote>
2119 <prgn>dpkg</prgn>'s internal databases are in a similar
2124 <sect id="controlsyntax">
2125 <heading>Syntax of control files</heading>
2128 A control file consists of one or more paragraphs of
2130 The paragraphs are also sometimes referred to as stanzas.
2132 The paragraphs are separated by blank lines. Some control
2133 files allow only one paragraph; others allow several, in
2134 which case each paragraph usually refers to a different
2135 package. (For example, in source packages, the first
2136 paragraph refers to the source package, and later paragraphs
2137 refer to binary packages generated from the source.)
2141 Each paragraph consists of a series of data fields; each
2142 field consists of the field name, followed by a colon and
2143 then the data/value associated with that field. It ends at
2144 the end of the line. Horizontal whitespace (spaces and
2145 tabs) may occur immediately before or after the value and is
2146 ignored there; it is conventional to put a single space
2147 after the colon. For example, a field might be:
2148 <example compact="compact">
2151 the field name is <tt>Package</tt> and the field value
2156 Some fields' values may span several lines; in this case
2157 each continuation line must start with a space or a tab.
2158 Any trailing spaces or tabs at the end of individual
2159 lines of a field value are ignored.
2163 Except where otherwise stated, only a single line of data is
2164 allowed and whitespace is not significant in a field body.
2165 Whitespace must not appear inside names (of packages,
2166 architectures, files or anything else) or version numbers,
2167 or between the characters of multi-character version
2172 Field names are not case-sensitive, but it is usual to
2173 capitalize the field names using mixed case as shown below.
2177 Blank lines, or lines consisting only of spaces and tabs,
2178 are not allowed within field values or between fields - that
2179 would mean a new paragraph.
2184 <sect id="sourcecontrolfiles">
2185 <heading>Source package control files -- <file>debian/control</file></heading>
2188 The <file>debian/control</file> file contains the most vital
2189 (and version-independent) information about the source package
2190 and about the binary packages it creates.
2194 The first paragraph of the control file contains information about
2195 the source package in general. The subsequent sets each describe a
2196 binary package that the source tree builds.
2200 The fields in the general paragraph (the first one, for the source
2203 <list compact="compact">
2204 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2205 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2206 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2207 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2208 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2209 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2210 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2215 The fields in the binary package paragraphs are:
2217 <list compact="compact">
2218 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2219 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2220 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2221 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2222 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2223 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2224 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2229 The syntax and semantics of the fields are described below.
2235 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2236 generate control files for binary packages (see below), by
2237 <prgn>dpkg-genchanges</prgn> to generate the
2238 <tt>.changes</tt> file to accompany the upload, and by
2239 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2240 source control file as part of a source archive.
2244 The fields here may contain variable references - their
2245 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2246 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2247 when they generate output control files.
2248 See <ref id="substvars"> for details.
2253 <sect id="binarycontrolfiles">
2254 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2257 The <file>DEBIAN/control</file> file contains the most vital
2258 (and version-dependent) information about a binary package.
2262 The fields in this file are:
2264 <list compact="compact">
2265 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2266 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2267 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2268 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2269 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2270 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2271 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2272 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2273 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2274 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2275 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2280 <sect id="debiansourcecontrolfiles">
2281 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2284 This file contains a series of fields, identified and
2285 separated just like the fields in the control file of
2286 a binary package. The fields are listed below; their
2287 syntax is described above, in <ref id="pkg-controlfields">.
2289 <list compact="compact">
2290 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2291 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2292 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2293 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2294 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2295 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2296 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2297 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2298 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2299 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2304 The source package control file is generated by
2305 <prgn>dpkg-source</prgn> when it builds the source
2306 archive, from other files in the source package,
2307 described above. When unpacking, it is checked against
2308 the files and directories in the other parts of the
2314 <sect id="debianchangesfiles">
2315 <heading>Debian changes files -- <file>.changes</file></heading>
2318 The .changes files are used by the Debian archive maintenance
2319 software to process updates to packages. They contain one
2320 paragraph which contains information from the
2321 <tt>debian/control</tt> file and other data about the
2322 source package gathered via <tt>debian/changelog</tt>
2323 and <tt>debian/rules</tt>.
2327 The fields in this file are:
2329 <list compact="compact">
2330 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2333 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2335 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2337 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2338 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2339 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2340 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2341 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2342 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2343 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2348 <sect id="controlfieldslist">
2349 <heading>List of fields</heading>
2351 <sect1 id="f-Source">
2352 <heading><tt>Source</tt></heading>
2355 This field identifies the source package name.
2359 In a main source control information, a <file>.changes</file>
2360 or a <file>.dsc</file> file this may contain only the name
2361 of the source package.
2365 In the control file of a binary package it may be followed
2366 by a version number in parentheses<footnote>
2367 It is customary to leave a space after the package name
2368 if a version number is specified.
2370 This version number may be omitted (and is, by
2371 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2372 the <tt>Version</tt> field of the binary package in
2373 question. The field itself may be omitted from a binary
2374 package control file when the source package has the same
2375 name and version as the binary package.
2379 <sect1 id="f-Maintainer">
2380 <heading><tt>Maintainer</tt></heading>
2383 The package maintainer's name and email address. The name
2384 should come first, then the email address inside angle
2385 brackets <tt><></tt> (in RFC822 format).
2389 If the maintainer's name contains a full stop then the
2390 whole field will not work directly as an email address due
2391 to a misfeature in the syntax specified in RFC822; a
2392 program using this field as an address must check for this
2393 and correct the problem if necessary (for example by
2394 putting the name in round brackets and moving it to the
2395 end, and bringing the email address forward).
2399 <sect1 id="f-Uploaders">
2400 <heading><tt>Uploaders</tt></heading>
2403 List of the names and email addresses of
2404 co-maintaintainers of the package, if any. If the package
2405 has other maintainers beside the one named in the <qref
2406 id="f-Maintainer">Maintainer field</qref>, they their
2407 names and email addresses should be listed here. The
2408 format is the same as that of the Maintainer tag, and
2409 multiple entries should be comma separated. This is an
2414 <sect1 id="f-Changed-By">
2415 <heading><tt>Changed-By</tt></heading>
2418 The name and email address of the person who changed the
2419 said package. Usually the name of the maintainer.
2420 All the rules for the Maintainer field apply here, too.
2424 <sect1 id="f-Section">
2425 <heading><tt>Section</tt></heading>
2428 This field specifies an application area into which the package
2429 has been classified. See <ref id="subsections">.
2433 When it appears in the <file>debian/control</file> file,
2434 it gives the value for the subfield of the same name in
2435 the <tt>Files</tt> field of the <file>.changes</file> file.
2436 It also gives the default for the same field in the binary
2441 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2442 field in the control file of a binary package - use the
2443 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2447 <sect1 id="f-Priority">
2448 <heading><tt>Priority</tt></heading>
2451 This field represents how important that it is that the user
2452 have the package installed. See <ref id="priorities">.
2456 When it appears in the <file>debian/control</file> file,
2457 it gives the value for the subfield of the same name in
2458 the <tt>Files</tt> field of the <file>.changes</file> file.
2459 It also gives the default for the same field in the binary
2464 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2465 field in the control file of a binary package - use the
2466 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2470 <sect1 id="f-Package">
2471 <heading><tt>Package</tt></heading>
2474 The name of the binary package.
2478 Package names must consist only of lower case letters
2479 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2480 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2481 They must be at least two characters long and must start
2482 with an alphanumeric character.
2486 <sect1 id="f-Architecture">
2487 <heading><tt>Architecture</tt></heading>
2490 Depending on context and the control file used, the
2491 <tt>Architecture</tt> field can include the following sets of
2494 <item>A unique single word identifying a Debian machine
2495 architecture, see <ref id="arch-spec">.
2496 <item><tt>all</tt>, which indicates an
2497 architecture-independent package.
2498 <item><tt>any</tt>, which indicates a package available
2499 for building on any architecture.
2500 <item><tt>source</tt>, which indicates a source package.
2505 In the main <file>debian/control</file> file in the source
2506 package, or in the source package control file
2507 <file>.dsc</file>, one may specify a list of architectures
2508 separated by spaces, or the special values <tt>any</tt> or
2513 Specifying <tt>any</tt> indicates that the source package
2514 isn't dependent on any particular architecture and should
2515 compile fine on any one. The produced binary package(s)
2516 will be specific to whatever the current build architecture
2518 This is the most often used setting, and is recommended
2519 for new packages that aren't <tt>Architecture: all</tt>.
2524 Specifying a list of architectures indicates that the source
2525 will build an architecture-dependent package, and will only
2526 work correctly on the listed architectures.<footnote>
2527 This is a setting used for a minority of cases where the
2528 program is not portable. Generally, it should not be used
2534 In a <file>.changes</file> file, the <tt>Architecture</tt>
2535 field lists the architecture(s) of the package(s)
2536 currently being uploaded. This will be a list; if the
2537 source for the package is also being uploaded, the special
2538 entry <tt>source</tt> is also present.
2542 See <ref id="debianrules"> for information how to get the
2543 architecture for the build process.
2547 <sect1 id="f-Essential">
2548 <heading><tt>Essential</tt></heading>
2551 This is a boolean field which may occur only in the
2552 control file of a binary package or in a per-package fields
2553 paragraph of a main source control data file.
2557 If set to <tt>yes</tt> then the package management system
2558 will refuse to remove the package (upgrading and replacing
2559 it is still possible). The other possible value is <tt>no</tt>,
2560 which is the same as not having the field at all.
2565 <heading>Package interrelationship fields:
2566 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2567 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2568 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2572 These fields describe the package's relationships with
2573 other packages. Their syntax and semantics are described
2574 in <ref id="relationships">.</p>
2577 <sect1 id="f-Standards-Version">
2578 <heading><tt>Standards-Version</tt></heading>
2581 The most recent version of the standards (the policy
2582 manual and associated texts) with which the package
2587 The version number has four components: major and minor
2588 version number and major and minor patch level. When the
2589 standards change in a way that requires every package to
2590 change the major number will be changed. Significant
2591 changes that will require work in many packages will be
2592 signaled by a change to the minor number. The major patch
2593 level will be changed for any change to the meaning of the
2594 standards, however small; the minor patch level will be
2595 changed when only cosmetic, typographical or other edits
2596 are made which neither change the meaning of the document
2597 nor affect the contents of packages.
2601 Thus only the first three components of the policy version
2602 are significant in the <em>Standards-Version</em> control
2603 field, and so either these three components or the all
2604 four components may be specified.<footnote>
2605 In the past, people specified the full version number
2606 in the Standards-Version field, for example "2.3.0.0".
2607 Since minor patch-level changes don't introduce new
2608 policy, it was thought it would be better to relax
2609 policy and only require the first 3 components to be
2610 specified, in this example "2.3.0". All four
2611 components may still be used if someone wishes to do so.
2617 <sect1 id="f-Version">
2618 <heading><tt>Version</tt></heading>
2621 The version number of a package. The format is:
2622 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2626 The three components here are:
2628 <tag><var>epoch</var></tag>
2631 This is a single (generally small) unsigned integer. It
2632 may be omitted, in which case zero is assumed. If it is
2633 omitted then the <var>upstream_version</var> may not
2638 It is provided to allow mistakes in the version numbers
2639 of older versions of a package, and also a package's
2640 previous version numbering schemes, to be left behind.
2644 <tag><var>upstream_version</var></tag>
2647 This is the main part of the version number. It is
2648 usually the version number of the original ("upstream")
2649 package from which the <file>.deb</file> file has been made,
2650 if this is applicable. Usually this will be in the same
2651 format as that specified by the upstream author(s);
2652 however, it may need to be reformatted to fit into the
2653 package management system's format and comparison
2658 The comparison behavior of the package management system
2659 with respect to the <var>upstream_version</var> is
2660 described below. The <var>upstream_version</var>
2661 portion of the version number is mandatory.
2665 The <var>upstream_version</var> may contain only
2666 alphanumerics<footnote>
2667 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2669 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2670 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2671 start with a digit. If there is no
2672 <var>debian_revision</var> then hyphens are not allowed;
2673 if there is no <var>epoch</var> then colons are not
2678 <tag><var>debian_revision</var></tag>
2681 This part of the version number specifies the version of
2682 the Debian package based on the upstream version. It
2683 may contain only alphanumerics and the characters
2684 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2685 compared in the same way as the
2686 <var>upstream_version</var> is.
2690 It is optional; if it isn't present then the
2691 <var>upstream_version</var> may not contain a hyphen.
2692 This format represents the case where a piece of
2693 software was written specifically to be turned into a
2694 Debian package, and so there is only one "debianization"
2695 of it and therefore no revision indication is required.
2699 It is conventional to restart the
2700 <var>debian_revision</var> at <tt>1</tt> each time the
2701 <var>upstream_version</var> is increased.
2705 The package management system will break the version
2706 number apart at the last hyphen in the string (if there
2707 is one) to determine the <var>upstream_version</var> and
2708 <var>debian_revision</var>. The absence of a
2709 <var>debian_revision</var> compares earlier than the
2710 presence of one (but note that the
2711 <var>debian_revision</var> is the least significant part
2712 of the version number).
2719 The <var>upstream_version</var> and <var>debian_revision</var>
2720 parts are compared by the package management system using the
2725 The strings are compared from left to right.
2729 First the initial part of each string consisting entirely of
2730 non-digit characters is determined. These two parts (one of
2731 which may be empty) are compared lexically. If a difference
2732 is found it is returned. The lexical comparison is a
2733 comparison of ASCII values modified so that all the letters
2734 sort earlier than all the non-letters.
2738 Then the initial part of the remainder of each string which
2739 consists entirely of digit characters is determined. The
2740 numerical values of these two parts are compared, and any
2741 difference found is returned as the result of the comparison.
2742 For these purposes an empty string (which can only occur at
2743 the end of one or both version strings being compared) counts
2748 These two steps (comparing and removing initial non-digit
2749 strings and initial digit strings) are repeated until a
2750 difference is found or both strings are exhausted.
2754 Note that the purpose of epochs is to allow us to leave behind
2755 mistakes in version numbering, and to cope with situations
2756 where the version numbering scheme changes. It is
2757 <em>not</em> intended to cope with version numbers containing
2758 strings of letters which the package management system cannot
2759 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2760 silly orderings (the author of this manual has heard of a
2761 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2762 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2763 <tt>2</tt> and so forth).
2767 <sect1 id="f-Description">
2768 <heading><tt>Description</tt></heading>
2771 In a source or binary control file, the <tt>Description</tt>
2772 field contains a description of the binary package, consisting
2773 of two parts, the synopsis or the short description, and the
2774 long description. The field's format is as follows:
2779 Description: <single line synopsis>
2780 <extended description over several lines>
2785 The lines in the extended description can have these formats:
2791 Those starting with a single space are part of a paragraph.
2792 Successive lines of this form will be word-wrapped when
2793 displayed. The leading space will usually be stripped off.
2797 Those starting with two or more spaces. These will be
2798 displayed verbatim. If the display cannot be panned
2799 horizontally, the displaying program will linewrap them "hard"
2800 (i.e., without taking account of word breaks). If it can they
2801 will be allowed to trail off to the right. None, one or two
2802 initial spaces may be deleted, but the number of spaces
2803 deleted from each line will be the same (so that you can have
2804 indenting work correctly, for example).
2808 Those containing a single space followed by a single full stop
2809 character. These are rendered as blank lines. This is the
2810 <em>only</em> way to get a blank line<footnote>
2811 Completely empty lines will not be rendered as blank lines.
2812 Instead, they will cause the parser to think you're starting
2813 a whole new record in the control file, and will therefore
2814 likely abort with an error.
2819 Those containing a space, a full stop and some more characters.
2820 These are for future expansion. Do not use them.
2826 Do not use tab characters. Their effect is not predictable.
2830 See <ref id="descriptions"> for further information on this.
2834 In a <file>.changes</file> file, the <tt>Description</tt> field
2835 contains a summary of the descriptions for the packages being
2840 The part of the field before the first newline is empty;
2841 thereafter each line has the name of a binary package and
2842 the summary description line from that binary package.
2843 Each line is indented by one space.
2848 <sect1 id="f-Distribution">
2849 <heading><tt>Distribution</tt></heading>
2852 In a <file>.changes</file> file or parsed changelog output
2853 this contains the (space-separated) name(s) of the
2854 distribution(s) where this version of the package should
2855 be installed. Valid distributions are determined by the
2856 archive maintainers.<footnote>
2857 Current distribution names are:
2858 <taglist compact="compact">
2859 <tag><em>stable</em></tag>
2861 This is the current "released" version of Debian
2862 GNU/Linux. Once the distribution is
2863 <em>stable</em> only security fixes and other
2864 major bug fixes are allowed. When changes are
2865 made to this distribution, the release number is
2866 increased (for example: 2.2r1 becomes 2.2r2 then
2870 <tag><em>unstable</em></tag>
2872 This distribution value refers to the
2873 <em>developmental</em> part of the Debian
2874 distribution tree. New packages, new upstream
2875 versions of packages and bug fixes go into the
2876 <em>unstable</em> directory tree. Download from
2877 this distribution at your own risk.
2880 <tag><em>testing</em></tag>
2882 This distribution value refers to the
2883 <em>testing</em> part of the Debian distribution
2884 tree. It receives its packages from the
2885 unstable distribution after a short time lag to
2886 ensure that there are no major issues with the
2887 unstable packages. It is less prone to breakage
2888 than unstable, but still risky. It is not
2889 possible to upload packages directly to
2893 <tag><em>frozen</em></tag>
2895 From time to time, the <em>testing</em>
2896 distribution enters a state of "code-freeze" in
2897 anticipation of release as a <em>stable</em>
2898 version. During this period of testing only
2899 fixes for existing or newly-discovered bugs will
2900 be allowed. The exact details of this stage are
2901 determined by the Release Manager.
2904 <tag><em>experimental</em></tag>
2906 The packages with this distribution value are
2907 deemed by their maintainers to be high
2908 risk. Oftentimes they represent early beta or
2909 developmental packages from various sources that
2910 the maintainers want people to try, but are not
2911 ready to be a part of the other parts of the
2912 Debian distribution tree. Download at your own
2918 You should list <em>all</em> distributions that the
2919 package should be installed into.
2923 More information is available in the Debian Developer's
2924 Reference, section "The Debian archive".
2931 <heading><tt>Date</tt></heading>
2934 This field includes the date the package was built or last edited.
2938 The value of this field is usually extracted from the
2939 <file>debian/changelog</file> file - see
2940 <ref id="dpkgchangelog">).
2944 <sect1 id="f-Format">
2945 <heading><tt>Format</tt></heading>
2948 This field specifies a format revision for the file.
2949 The most current format described in the Policy Manual
2950 is version <strong>1.5</strong>. The syntax of the
2951 format value is the same as that of a package version
2952 number except that no epoch or Debian revision is allowed
2953 - see <ref id="f-Version">.
2957 <sect1 id="f-Urgency">
2958 <heading><tt>Urgency</tt></heading>
2961 This is a description of how important it is to upgrade to
2962 this version from previous ones. It consists of a single
2963 keyword usually taking one of the values <tt>low</tt>,
2964 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2965 followed by an optional commentary (separated by a space)
2966 which is usually in parentheses. For example:
2969 Urgency: low (HIGH for users of diversions)
2975 The value of this field is usually extracted from the
2976 <file>debian/changelog</file> file - see
2977 <ref id="dpkgchangelog">.
2981 <sect1 id="f-Changes">
2982 <heading><tt>Changes</tt></heading>
2985 This field contains the human-readable changes data, describing
2986 the differences between the last version and the current one.
2990 There should be nothing in this field before the first
2991 newline; all the subsequent lines must be indented by at
2992 least one space; blank lines must be represented by a line
2993 consiting only of a space and a full stop.
2997 The value of this field is usually extracted from the
2998 <file>debian/changelog</file> file - see
2999 <ref id="dpkgchangelog">).
3003 Each version's change information should be preceded by a
3004 "title" line giving at least the version, distribution(s)
3005 and urgency, in a human-readable way.
3009 If data from several versions is being returned the entry
3010 for the most recent version should be returned first, and
3011 entries should be separated by the representation of a
3012 blank line (the "title" line may also be followed by the
3013 representation of blank line).
3017 <sect1 id="f-Binary">
3018 <heading><tt>Binary</tt></heading>
3021 This field is a list of binary packages.
3025 When it appears in the <file>.dsc</file> file it is the list
3026 of binary packages which a source package can produce. It
3027 does not necessarily produce all of these binary packages
3028 for every architecture. The source control file doesn't
3029 contain details of which architectures are appropriate for
3030 which of the binary packages.
3034 When it appears in a <file>.changes</file> file it lists the
3035 names of the binary packages actually being uploaded.
3039 The syntax is a list of binary packages separated by
3041 A space after each comma is conventional.
3042 </footnote>. Currently the packages must be separated using
3043 only spaces in the <file>.changes</file> file.
3047 <sect1 id="f-Installed-Size">
3048 <heading><tt>Installed-Size</tt></heading>
3051 This field appears in the control files of binary
3052 packages, and in the <file>Packages</file> files. It gives
3053 the total amount of disk space required to install the
3058 The disk space is represented in kilobytes as a simple
3063 <sect1 id="f-Files">
3064 <heading><tt>Files</tt></heading>
3067 This field contains a list of files with information about
3068 each one. The exact information and syntax varies with
3069 the context. In all cases the part of the field
3070 contents on the same line as the field name is empty. The
3071 remainder of the field is one line per file, each line
3072 being indented by one space and containing a number of
3073 sub-fields separated by spaces.
3077 In the <file>.dsc</file> file, each line contains the MD5
3078 checksum, size and filename of the tar file and (if applicable)
3079 diff file which make up the remainder of the source
3081 That is, the parts which are not the <tt>.dsc</tt>.
3083 The exact forms of the filenames are described
3084 in <ref id="pkg-sourcearchives">.
3088 In the <file>.changes</file> file this contains one line per
3089 file being uploaded. Each line contains the MD5 checksum,
3090 size, section and priority and the filename.
3091 The <qref id="f-Section">section</qref>
3092 and <qref id="f-Priority">priority</qref>
3093 are the values of the corresponding fields in
3094 the main source control file. If no section or priority is
3095 specified then <tt>-</tt> should be used, though section
3096 and priority values must be specified for new packages to
3097 be installed properly.
3101 The special value <tt>byhand</tt> for the section in a
3102 <tt>.changes</tt> file indicates that the file in question
3103 is not an ordinary package file and must by installed by
3104 hand by the distribution maintainers. If the section is
3105 <tt>byhand</tt> the priority should be <tt>-</tt>.
3109 If a new Debian revision of a package is being shipped and
3110 no new original source archive is being distributed the
3111 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3112 entry for the original source archive
3113 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3114 but the <file>.changes</file> file should leave it out. In
3115 this case the original source archive on the distribution
3116 site must match exactly, byte-for-byte, the original
3117 source archive which was used to generate the
3118 <file>.dsc</file> file and diff which are being uploaded.</p>
3121 <sect1 id="f-Closes">
3122 <heading><tt>Closes</tt></heading>
3125 A space-separated list of bug report numbers that the upload
3126 governed by the .changes file closes.
3133 <heading>User-defined fields</heading>
3136 Additional user-defined fields may be added to the
3137 source package control file. Such fields will be
3138 ignored, and not copied to (for example) binary or
3139 source package control files or upload control files.
3143 If you wish to add additional unsupported fields to
3144 these output files you should use the mechanism
3149 Fields in the main source control information file with
3150 names starting <tt>X</tt>, followed by one or more of
3151 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3152 be copied to the output files. Only the part of the
3153 field name after the hyphen will be used in the output
3154 file. Where the letter <tt>B</tt> is used the field
3155 will appear in binary package control files, where the
3156 letter <tt>S</tt> is used in source package control
3157 files and where <tt>C</tt> is used in upload control
3158 (<tt>.changes</tt>) files.
3162 For example, if the main source information control file
3165 XBS-Comment: I stand between the candle and the star.
3167 then the binary and source package control files will contain the
3170 Comment: I stand between the candle and the star.
3179 <chapt id="maintainerscripts">
3180 <heading>Package maintainer scripts and installation procedure</heading>
3183 <heading>Introduction to package maintainer scripts</heading>
3186 It is possible to supply scripts as part of a package which
3187 the package management system will run for you when your
3188 package is installed, upgraded or removed.
3192 These scripts are the files <prgn>preinst</prgn>,
3193 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3194 control area of the package. They must be proper executable
3195 files; if they are scripts (which is recommended), they must
3196 start with the usual <tt>#!</tt> convention. They should be
3197 readable and executable by anyone, and not world-writable.
3201 The package management system looks at the exit status from
3202 these scripts. It is important that they exit with a
3203 non-zero status if there is an error, so that the package
3204 management system can stop its processing. For shell
3205 scripts this means that you <em>almost always</em> need to
3206 use <tt>set -e</tt> (this is usually true when writing shell
3207 scripts, in fact). It is also important, of course, that
3208 they don't exit with a non-zero status if everything went
3213 When a package is upgraded a combination of the scripts from
3214 the old and new packages is called during the upgrade
3215 procedure. If your scripts are going to be at all
3216 complicated you need to be aware of this, and may need to
3217 check the arguments to your scripts.
3221 Broadly speaking the <prgn>preinst</prgn> is called before
3222 (a particular version of) a package is installed, and the
3223 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3224 before (a version of) a package is removed and the
3225 <prgn>postrm</prgn> afterwards.
3229 Programs called from maintainer scripts should not normally
3230 have a path prepended to them. Before installation is
3231 started, the package management system checks to see if the
3232 programs <prgn>ldconfig</prgn>,
3233 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3234 and <prgn>update-rc.d</prgn> can be found via the
3235 <tt>PATH</tt> environment variable. Those programs, and any
3236 other program that one would expect to be on the
3237 <tt>PATH</tt>, should thus be invoked without an absolute
3238 pathname. Maintainer scripts should also not reset the
3239 <tt>PATH</tt>, though they might choose to modify it by
3240 prepending or appending package-specific directories. These
3241 considerations really apply to all shell scripts.</p>
3244 <sect id="idempotency">
3245 <heading>Maintainer scripts Idempotency</heading>
3248 It is necessary for the error recovery procedures that the
3249 scripts be idempotent. This means that if it is run
3250 successfully, and then it is called again, it doesn't bomb
3251 out or cause any harm, but just ensures that everything is
3252 the way it ought to be. If the first call failed, or
3253 aborted half way through for some reason, the second call
3254 should merely do the things that were left undone the first
3255 time, if any, and exit with a success status if everything
3257 This is so that if an error occurs, the user interrupts
3258 <prgn>dpkg</prgn> or some other unforeseen circumstance
3259 happens you don't leave the user with a badly-broken
3260 package when <prgn>dpkg</prgn> attempts to repeat the
3266 <sect id="controllingterminal">
3267 <heading>Controlling terminal for maintainer scripts</heading>
3270 The maintainer scripts are guaranteed to run with a
3271 controlling terminal and can interact with the user.
3272 If they need to prompt for passwords, do full-screen
3273 interaction or something similar you should do these
3274 things to and from <file>/dev/tty</file>, since
3275 <prgn>dpkg</prgn> will at some point redirect scripts'
3276 standard input and output so that it can log the
3277 installation process. Likewise, because these scripts
3278 may be executed with standard output redirected into a
3279 pipe for logging purposes, Perl scripts should set
3280 unbuffered output by setting <tt>$|=1</tt> so that the
3281 output is printed immediately rather than being
3286 Each script should return a zero exit status for
3287 success, or a nonzero one for failure.
3291 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3296 <list compact="compact">
3298 <var>new-preinst</var> <tt>install</tt>
3301 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3304 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3307 <var>old-preinst</var> <tt>abort-upgrade</tt>
3308 <var>new-version</var>
3313 <list compact="compact">
3315 <var>postinst</var> <tt>configure</tt>
3316 <var>most-recently-configured-version</var>
3319 <var>old-postinst</var> <tt>abort-upgrade</tt>
3320 <var>new-version</var>
3323 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3324 <tt>in-favour</tt> <var>package</var>
3325 <var>new-version</var>
3328 <var>deconfigured's-postinst</var>
3329 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3330 <var>failed-install-package</var> <var>version</var>
3331 <tt>removing</tt> <var>conflicting-package</var>
3337 <list compact="compact">
3339 <var>prerm</var> <tt>remove</tt>
3342 <var>old-prerm</var> <tt>upgrade</tt>
3343 <var>new-version</var>
3346 <var>new-prerm</var> <tt>failed-upgrade</tt>
3347 <var>old-version</var>
3350 <var>conflictor's-prerm</var> <tt>remove</tt>
3351 <tt>in-favour</tt> <var>package</var>
3352 <var>new-version</var>
3355 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3356 <tt>in-favour</tt> <var>package-being-installed</var>
3357 <var>version</var> <tt>removing</tt>
3358 <var>conflicting-package</var>
3364 <list compact="compact">
3366 <var>postrm</var> <tt>remove</tt>
3369 <var>postrm</var> <tt>purge</tt>
3372 <var>old-postrm</var> <tt>upgrade</tt>
3373 <var>new-version</var>
3376 <var>new-postrm</var> <tt>failed-upgrade</tt>
3377 <var>old-version</var>
3380 <var>new-postrm</var> <tt>abort-install</tt>
3383 <var>new-postrm</var> <tt>abort-install</tt>
3384 <var>old-version</var>
3387 <var>new-postrm</var> <tt>abort-upgrade</tt>
3388 <var>old-version</var>
3391 <var>disappearer's-postrm</var> <tt>disappear</tt>
3392 <var>overwriter</var>
3393 <var>overwriter-version</var>
3399 <sect id="unpackphase">
3400 <heading>Details of unpack phase of installation or upgrade</heading>
3403 The procedure on installation/upgrade/overwrite/disappear
3404 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3405 stage of <tt>dpkg --install</tt>) is as follows. In each
3406 case, if a major error occurs (unless listed below) the
3407 actions are, in general, run backwards - this means that the
3408 maintainer scripts are run with different arguments in
3409 reverse order. These are the "error unwind" calls listed
3416 If a version of the package is already installed, call
3417 <example compact="compact">
3418 <var>old-prerm</var> upgrade <var>new-version</var>
3422 If the script runs but exits with a non-zero
3423 exit status, <prgn>dpkg</prgn> will attempt:
3424 <example compact="compact">
3425 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3427 Error unwind, for both the above cases:
3428 <example compact="compact">
3429 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3436 If a "conflicting" package is being removed at the same time:
3439 If any packages depended on that conflicting
3440 package and <tt>--auto-deconfigure</tt> is
3441 specified, call, for each such package:
3442 <example compact="compact">
3443 <var>deconfigured's-prerm</var> deconfigure \
3444 in-favour <var>package-being-installed</var> <var>version</var> \
3445 removing <var>conflicting-package</var> <var>version</var>
3448 <example compact="compact">
3449 <var>deconfigured's-postinst</var> abort-deconfigure \
3450 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3451 removing <var>conflicting-package</var> <var>version</var>
3453 The deconfigured packages are marked as
3454 requiring configuration, so that if
3455 <tt>--install</tt> is used they will be
3456 configured again if possible.
3459 To prepare for removal of the conflicting package, call:
3460 <example compact="compact">
3461 <var>conflictor's-prerm</var> remove \
3462 in-favour <var>package</var> <var>new-version</var>
3465 <example compact="compact">
3466 <var>conflictor's-postinst</var> abort-remove \
3467 in-favour <var>package</var> <var>new-version</var>
3476 If the package is being upgraded, call:
3477 <example compact="compact">
3478 <var>new-preinst</var> upgrade <var>old-version</var>
3482 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3484 If that too fails, then
3486 <var>old-postinst</var> abort-upgrade <var>old-version</var>
3491 Otherwise, if the package had some configuration
3492 files from a previous version installed (i.e., it
3493 is in the "configuration files only" state):
3494 <example compact="compact">
3495 <var>new-preinst</var> install <var>old-version</var>
3499 <var>new-postrm</var> abort-install <var>old-version</var>
3503 Otherwise (i.e., the package was completely purged):
3504 <example compact="compact">
3505 <var>new-preinst</var> install
3508 <example compact="compact">
3509 <var>new-postrm</var> abort-install
3517 The new package's files are unpacked, overwriting any
3518 that may be on the system already, for example any
3519 from the old version of the same package or from
3520 another package. Backups of the old files are kept
3521 temporarily, and if anything goes wrong the package
3522 management system will attempt to put them back as
3523 part of the error unwind.
3527 It is an error for a package to contain files which
3528 are on the system in another package, unless
3529 <tt>Replaces</tt> is used (see <ref id="replaces">).
3531 The following paragraph is not currently the case:
3532 Currently the <tt>- - force-overwrite</tt> flag is
3533 enabled, downgrading it to a warning, but this may not
3539 It is a more serious error for a package to contain a
3540 plain file or other kind of non-directory where another
3541 package has a directory (again, unless
3542 <tt>Replaces</tt> is used). This error can be
3543 overridden if desired using
3544 <tt>--force-overwrite-dir</tt>, but this is not
3549 Packages which overwrite each other's files produce
3550 behavior which, though deterministic, is hard for the
3551 system administrator to understand. It can easily
3552 lead to "missing" programs if, for example, a package
3553 is installed which overwrites a file from another
3554 package, and is then removed again.<footnote>
3555 Part of the problem is due to what is arguably a
3556 bug in <prgn>dpkg</prgn>.
3561 A directory will never be replaced by a symbolic link
3562 to a directory or vice versa; instead, the existing
3563 state (symlink or not) will be left alone and
3564 <prgn>dpkg</prgn> will follow the symlink if there is
3573 If the package is being upgraded, call
3574 <example compact="compact">
3575 <var>old-postrm</var> upgrade <var>new-version</var>
3579 If this fails, <prgn>dpkg</prgn> will attempt:
3580 <example compact="compact">
3581 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3583 Error unwind, for both cases:
3584 <example compact="compact">
3585 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3592 This is the point of no return - if
3593 <prgn>dpkg</prgn> gets this far, it won't back off
3594 past this point if an error occurs. This will
3595 leave the package in a fairly bad state, which
3596 will require a successful re-installation to clear
3597 up, but it's when <prgn>dpkg</prgn> starts doing
3598 things that are irreversible.
3603 Any files which were in the old version of the package
3604 but not in the new are removed.
3608 The new file list replaces the old.
3612 The new maintainer scripts replace the old.
3616 Any packages all of whose files have been overwritten
3617 during the installation, and which aren't required for
3618 dependencies, are considered to have been removed.
3619 For each such package
3622 <prgn>dpkg</prgn> calls:
3623 <example compact="compact">
3624 <var>disappearer's-postrm</var> disappear \
3625 <var>overwriter</var> <var>overwriter-version</var>
3629 The package's maintainer scripts are removed.
3632 It is noted in the status database as being in a
3633 sane state, namely not installed (any conffiles
3634 it may have are ignored, rather than being
3635 removed by <prgn>dpkg</prgn>). Note that
3636 disappearing packages do not have their prerm
3637 called, because <prgn>dpkg</prgn> doesn't know
3638 in advance that the package is going to
3645 Any files in the package we're unpacking that are also
3646 listed in the file lists of other packages are removed
3647 from those lists. (This will lobotomize the file list
3648 of the "conflicting" package if there is one.)
3652 The backup files made during installation, above, are
3658 The new package's status is now sane, and recorded as
3663 Here is another point of no return - if the
3664 conflicting package's removal fails we do not unwind
3665 the rest of the installation; the conflicting package
3666 is left in a half-removed limbo.
3671 If there was a conflicting package we go and do the
3672 removal actions (described below), starting with the
3673 removal of the conflicting package's files (any that
3674 are also in the package being installed have already
3675 been removed from the conflicting package's file list,
3676 and so do not get removed now).
3682 <sect id="configdetails"><heading>Details of configuration</heading>
3685 When we configure a package (this happens with <tt>dpkg
3686 --install</tt> and <tt>dpkg --configure</tt>), we first
3687 update any <tt>conffile</tt>s and then call:
3688 <example compact="compact">
3689 <var>postinst</var> configure <var>most-recently-configured-version</var>
3694 No attempt is made to unwind after errors during
3699 If there is no most recently configured version
3700 <prgn>dpkg</prgn> will pass a null argument.
3703 Historical note: Truly ancient (pre-1997) versions of
3704 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3705 (including the angle brackets) in this case. Even older
3706 ones did not pass a second argument at all, under any
3707 circumstance. Note that upgrades using such an old dpkg
3708 version are unlikely to work for other reasons, even if
3709 this old argument behavior is handled by your postinst script.
3715 <sect id="removedetails"><heading>Details of removal and/or
3716 configuration purging</heading>
3721 <example compact="compact">
3722 <var>prerm</var> remove
3726 The package's files are removed (except <tt>conffile</tt>s).
3729 <example compact="compact">
3730 <var>postrm</var> remove
3735 All the maintainer scripts except the <prgn>postrm</prgn>
3740 If we aren't purging the package we stop here. Note
3741 that packages which have no <prgn>postrm</prgn> and no
3742 <tt>conffile</tt>s are automatically purged when
3743 removed, as there is no difference except for the
3744 <prgn>dpkg</prgn> status.
3748 The <tt>conffile</tt>s and any backup files
3749 (<tt>~</tt>-files, <tt>#*#</tt> files,
3750 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3754 <example compact="compact">
3755 <var>postrm</var> purge
3759 The package's file list is removed.
3763 If there are problems during this process, we call
3764 <example compact="compact">postinst
3765 abort-remove</example>. No other attempt is made to unwind
3766 after errors during removal.
3772 <chapt id="relationships">
3773 <heading>Declaring relationships between packages</heading>
3775 <sect id="depsyntax">
3776 <heading>Syntax of relationship fields</heading>
3779 These fields all have a uniform syntax. They are a list of
3780 package names separated by commas.
3784 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3785 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3786 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3787 control file fields of the package, which declare
3788 dependencies on other packages, the package names listed may
3789 also include lists of alternative package names, separated
3790 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3791 if any one of the alternative packages is installed, that
3792 part of the dependency is considered to be satisfied.
3796 All of the fields except for <tt>Provides</tt> may restrict
3797 their applicability to particular versions of each named
3798 package. This is done in parentheses after each individual
3799 package name; the parentheses should contain a relation from
3800 the list below followed by a version number, in the format
3801 described in <ref id="f-Version">.
3805 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3806 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3807 strictly earlier, earlier or equal, exactly equal, later or
3808 equal and strictly later, respectively. The deprecated
3809 forms <tt><</tt> and <tt>></tt> were used to mean
3810 earlier/later or equal, rather than strictly earlier/later,
3811 so they should not appear in new packages (though
3812 <prgn>dpkg</prgn> still supports them).
3816 Whitespace may appear at any point in the version
3817 specification subject to the rules in <ref
3818 id="controlsyntax">, and must appear where it's necessary to
3819 disambiguate; it is not otherwise significant. For
3820 consistency and in case of future changes to
3821 <prgn>dpkg</prgn> it is recommended that a single space be
3822 used after a version relationship and before a version
3823 number; it is also conventional to put a single space after
3824 each comma, on either side of each vertical bar, and before
3825 each open parenthesis.
3829 For example, a list of dependencies might appear as:
3830 <example compact="compact">
3833 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3838 All fields that specify build-time relationships
3839 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3840 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3841 may be restricted to a certain set of architectures. This
3842 is indicated in brackets after each individual package name and
3843 the optional version specification. The brackets enclose a
3844 list of Debian architecture names separated by whitespace.
3845 Exclamation marks may be prepended to each of the names.
3846 (It is not permitted for some names to be prepended with
3847 exclamation marks and others not.) If the current Debian
3848 host architecture is not in this list and there are no
3849 exclamation marks in the list, or it is in the list with a
3850 prepended exclamation mark, the package name and the
3851 associated version specification are ignored completely for
3852 the purposes of defining the relationships.
3857 <example compact="compact">
3859 Build-Depends-Indep: texinfo
3860 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3861 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3866 Note that the binary package relationship fields such as
3867 <tt>Depends</tt> appear in one of the binary package
3868 sections of the control file, whereas the build-time
3869 relationships such as <tt>Build-Depends</tt> appear in the
3870 source package section of the control file (which is the
3875 <sect id="binarydeps">
3876 <heading>Binary Dependencies - <tt>Depends</tt>,
3877 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3878 <tt>Pre-Depends</tt>
3882 Packages can declare in their control file that they have
3883 certain relationships to other packages - for example, that
3884 they may not be installed at the same time as certain other
3885 packages, and/or that they depend on the presence of others.
3889 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3890 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3891 <tt>Conflicts</tt> control file fields.
3895 These six fields are used to declare a dependency
3896 relationship by one package on another. Except for
3897 <tt>Enhances</tt>, they appear in the depending (binary)
3898 package's control file. (<tt>Enhances</tt> appears in the
3899 recommending package's control file.)
3903 A <tt>Depends</tt> field takes effect <em>only</em> when a
3904 package is to be configured. It does not prevent a package
3905 being on the system in an unconfigured state while its
3906 dependencies are unsatisfied, and it is possible to replace
3907 a package whose dependencies are satisfied and which is
3908 properly installed with a different version whose
3909 dependencies are not and cannot be satisfied; when this is
3910 done the depending package will be left unconfigured (since
3911 attempts to configure it will give errors) and will not
3912 function properly. If it is necessary, a
3913 <tt>Pre-Depends</tt> field can be used, which has a partial
3914 effect even when a package is being unpacked, as explained
3915 in detail below. (The other three dependency fields,
3916 <tt>Recommends</tt>, <tt>Suggests</tt> and
3917 <tt>Enhances</tt>, are only used by the various front-ends
3918 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3922 For this reason packages in an installation run are usually
3923 all unpacked first and all configured later; this gives
3924 later versions of packages with dependencies on later
3925 versions of other packages the opportunity to have their
3926 dependencies satisfied.
3930 The <tt>Depends</tt> field thus allows package maintainers
3931 to impose an order in which packages should be configured.
3935 The meaning of the five dependency fields is as follows:
3937 <tag><tt>Depends</tt></tag>
3940 This declares an absolute dependency. A package will
3941 not be configured unless all of the packages listed in
3942 its <tt>Depends</tt> field have been correctly
3947 The <tt>Depends</tt> field should be used if the
3948 depended-on package is required for the depending
3949 package to provide a significant amount of
3954 The <tt>Depends</tt> field should also be used if the
3955 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3956 <prgn>postrm</prgn> scripts require the package to be
3957 present in order to run. Note, however, that the
3958 <prgn>postrm</prgn> cannot rely on any non-essential
3959 packages to be present during the <tt>purge</tt>
3963 <tag><tt>Recommends</tt></tag>
3966 This declares a strong, but not absolute, dependency.
3970 The <tt>Recommends</tt> field should list packages
3971 that would be found together with this one in all but
3972 unusual installations.
3976 <tag><tt>Suggests</tt></tag>
3978 This is used to declare that one package may be more
3979 useful with one or more others. Using this field
3980 tells the packaging system and the user that the
3981 listed packages are related to this one and can
3982 perhaps enhance its usefulness, but that installing
3983 this one without them is perfectly reasonable.
3986 <tag><tt>Enhances</tt></tag>
3988 This field is similar to Suggests but works in the
3989 opposite direction. It is used to declare that a
3990 package can enhance the functionality of another
3994 <tag><tt>Pre-Depends</tt></tag>
3997 This field is like <tt>Depends</tt>, except that it
3998 also forces <prgn>dpkg</prgn> to complete installation
3999 of the packages named before even starting the
4000 installation of the package which declares the
4001 pre-dependency, as follows:
4005 When a package declaring a pre-dependency is about to
4006 be <em>unpacked</em> the pre-dependency can be
4007 satisfied if the depended-on package is either fully
4008 configured, <em>or even if</em> the depended-on
4009 package(s) are only unpacked or half-configured,
4010 provided that they have been configured correctly at
4011 some point in the past (and not removed or partially
4012 removed since). In this case, both the
4013 previously-configured and currently unpacked or
4014 half-configured versions must satisfy any version
4015 clause in the <tt>Pre-Depends</tt> field.
4019 When the package declaring a pre-dependency is about
4020 to be <em>configured</em>, the pre-dependency will be
4021 treated as a normal <tt>Depends</tt>, that is, it will
4022 be considered satisfied only if the depended-on
4023 package has been correctly configured.
4027 <tt>Pre-Depends</tt> should be used sparingly,
4028 preferably only by packages whose premature upgrade or
4029 installation would hamper the ability of the system to
4030 continue with any upgrade that might be in progress.
4034 <tt>Pre-Depends</tt> are also required if the
4035 <prgn>preinst</prgn> script depends on the named
4036 package. It is best to avoid this situation if
4044 When selecting which level of dependency to use you should
4045 consider how important the depended-on package is to the
4046 functionality of the one declaring the dependency. Some
4047 packages are composed of components of varying degrees of
4048 importance. Such a package should list using
4049 <tt>Depends</tt> the package(s) which are required by the
4050 more important components. The other components'
4051 requirements may be mentioned as Suggestions or
4052 Recommendations, as appropriate to the components' relative
4057 <sect id="conflicts">
4058 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4061 When one binary package declares a conflict with another
4062 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4063 refuse to allow them to be installed on the system at the
4068 If one package is to be installed, the other must be removed
4069 first - if the package being installed is marked as
4070 replacing (see <ref id="replaces">) the one on the system,
4071 or the one on the system is marked as deselected, or both
4072 packages are marked <tt>Essential</tt>, then
4073 <prgn>dpkg</prgn> will automatically remove the package
4074 which is causing the conflict, otherwise it will halt the
4075 installation of the new package with an error. This
4076 mechanism is specifically designed to produce an error when
4077 the installed package is <tt>Essential</tt>, but the new
4082 A package will not cause a conflict merely because its
4083 configuration files are still installed; it must be at least
4088 A special exception is made for packages which declare a
4089 conflict with their own package name, or with a virtual
4090 package which they provide (see below): this does not
4091 prevent their installation, and allows a package to conflict
4092 with others providing a replacement for it. You use this
4093 feature when you want the package in question to be the only
4094 package providing some feature.
4098 A <tt>Conflicts</tt> entry should almost never have an
4099 "earlier than" version clause. This would prevent
4100 <prgn>dpkg</prgn> from upgrading or installing the package
4101 which declared such a conflict until the upgrade or removal
4102 of the conflicted-with package had been completed.
4106 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4110 As well as the names of actual ("concrete") packages, the
4111 package relationship fields <tt>Depends</tt>,
4112 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4113 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4114 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4115 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4116 may mention "virtual packages".
4120 A <em>virtual package</em> is one which appears in the
4121 <tt>Provides</tt> control file field of another package.
4122 The effect is as if the package(s) which provide a
4123 particular virtual package name had been listed by name
4124 everywhere the virtual package name appears. (See also <ref
4129 If there are both concrete and virtual packages of the same
4130 name, then the dependency may be satisfied (or the conflict
4131 caused) by either the concrete package with the name in
4132 question or any other concrete package which provides the
4133 virtual package with the name in question. This is so that,
4134 for example, supposing we have
4135 <example compact="compact">
4139 and someone else releases an enhanced version of the
4140 <tt>bar</tt> package (for example, a non-US variant), they
4142 <example compact="compact">
4146 and the <tt>bar-plus</tt> package will now also satisfy the
4147 dependency for the <tt>foo</tt> package.
4151 If a dependency or a conflict has a version number attached
4152 then only real packages will be considered to see whether
4153 the relationship is satisfied (or the prohibition violated,
4154 for a conflict) - it is assumed that a real package which
4155 provides the virtual package is not of the "right" version.
4156 So, a <tt>Provides</tt> field may not contain version
4157 numbers, and the version number of the concrete package
4158 which provides a particular virtual package will not be
4159 looked at when considering a dependency on or conflict with
4160 the virtual package name.
4164 It is likely that the ability will be added in a future
4165 release of <prgn>dpkg</prgn> to specify a version number for
4166 each virtual package it provides. This feature is not yet
4167 present, however, and is expected to be used only
4172 If you want to specify which of a set of real packages
4173 should be the default to satisfy a particular dependency on
4174 a virtual package, you should list the real package as an
4175 alternative before the virtual one.
4180 <sect id="replaces"><heading>Overwriting files and replacing
4181 packages - <tt>Replaces</tt></heading>
4184 Packages can declare in their control file that they should
4185 overwrite files in certain other packages, or completely
4186 replace other packages. The <tt>Replaces</tt> control file
4187 field has these two distinct purposes.
4190 <sect1><heading>Overwriting files in other packages</heading>
4193 Firstly, as mentioned before, it is usually an error for a
4194 package to contain files which are on the system in
4199 However, if the overwriting package declares that it
4200 <tt>Replaces</tt> the one containing the file being
4201 overwritten, then <prgn>dpkg</prgn> will replace the file
4202 from the old package with that from the new. The file
4203 will no longer be listed as "owned" by the old package.
4207 If a package is completely replaced in this way, so that
4208 <prgn>dpkg</prgn> does not know of any files it still
4209 contains, it is considered to have "disappeared". It will
4210 be marked as not wanted on the system (selected for
4211 removal) and not installed. Any <tt>conffile</tt>s
4212 details noted for the package will be ignored, as they
4213 will have been taken over by the overwriting package. The
4214 package's <prgn>postrm</prgn> script will be run with a
4215 special argument to allow the package to do any final
4216 cleanup required. See <ref id="mscriptsinstact">.
4219 Replaces is a one way relationship -- you have to
4220 install the replacing package after the replaced
4227 For this usage of <tt>Replaces</tt>, virtual packages (see
4228 <ref id="virtual">) are not considered when looking at a
4229 <tt>Replaces</tt> field - the packages declared as being
4230 replaced must be mentioned by their real names.
4234 Furthermore, this usage of <tt>Replaces</tt> only takes
4235 effect when both packages are at least partially on the
4236 system at once, so that it can only happen if they do not
4237 conflict or if the conflict has been overridden.
4242 <sect1><heading>Replacing whole packages, forcing their
4246 Secondly, <tt>Replaces</tt> allows the packaging system to
4247 resolve which package should be removed when there is a
4248 conflict - see <ref id="conflicts">. This usage only
4249 takes effect when the two packages <em>do</em> conflict,
4250 so that the two usages of this field do not interfere with
4255 In this situation, the package declared as being replaced
4256 can be a virtual package, so for example, all mail
4257 transport agents (MTAs) would have the following fields in
4258 their control files:
4259 <example compact="compact">
4260 Provides: mail-transport-agent
4261 Conflicts: mail-transport-agent
4262 Replaces: mail-transport-agent
4264 ensuring that only one MTA can be installed at any one
4269 <sect id="sourcebinarydeps">
4270 <heading>Relationships between source and binary packages -
4271 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4272 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4276 Source packages that require certain binary packages to be
4277 installed or absent at the time of building the package
4278 can declare relationships to those binary packages.
4282 This is done using the <tt>Build-Depends</tt>,
4283 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4284 <tt>Build-Conflicts-Indep</tt> control file fields.
4288 Build-dependencies on "build-essential" binary packages can be
4289 omitted. Please see <ref id="pkg-relations"> for more information.
4293 The dependencies and conflicts they define must be satisfied
4294 (as defined earlier for binary packages) in order to invoke
4295 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4297 If you make "build-arch" or "binary-arch", you need
4298 Build-Depends. If you make "build-indep" or
4299 "binary-indep", you need Build-Depends and
4300 Build-Depends-Indep. If you make "build" or "binary",
4304 There is no Build-Depends-Arch; the autobuilders will
4305 only need the Build-Depends if they know how to build
4306 only build-arch and binary-arch. Anyone building the
4307 build-indep/binary-indep targets is basically assumed to
4308 be building the whole package and so installs all build
4312 The purpose of the original split, I recall, was so that
4313 the autobuilders wouldn't need to install extra packages
4314 needed only for the binary-indep targets. But without a
4315 build-arch/build-indep split, this didn't work, since
4316 most of the work is done in the build target, not in the
4322 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4324 The <tt>Build-Depends</tt> and
4325 <tt>Build-Conflicts</tt> fields must be satisfied when
4326 any of the following targets is invoked:
4327 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4328 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4329 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4331 <tag><tt>Build-Depends-Indep</tt>,
4332 <tt>Build-Conflicts-Indep</tt></tag>
4334 The <tt>Build-Depends-Indep</tt> and
4335 <tt>Build-Conflicts-Indep</tt> fields must be
4336 satisfied when any of the following targets is
4337 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4338 <tt>binary</tt> and <tt>binary-indep</tt>.
4348 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4351 Packages containing shared libraries must be constructed with
4352 a little care to make sure that the shared library is always
4353 available. This is especially important for packages whose
4354 shared libraries are vitally important, such as the C library
4355 (currently <tt>libc6</tt>).
4359 Packages involving shared libraries should be split up into
4360 several binary packages. This section mostly deals with how
4361 this separation is to be accomplished; rules for files within
4362 the shared library packages are in <ref id="libraries"> instead.
4365 <sect id="sharedlibs-runtime">
4366 <heading>Run-time shared libraries</heading>
4369 The run-time shared library needs to be placed in a package
4370 whose name changes whenever the shared object version
4373 Since it is common place to install several versions of a
4374 package that just provides shared libraries, it is a
4375 good idea that that the library package should not
4376 contain any extraneous non-versioned files, unless they
4377 happen to be in versioned directories.</p>
4379 The most common mechanism is to place it in a package
4381 <package><var>libraryname</var><var>soversion</var></package>,
4382 where <file><var>soversion</var></file> is the version number
4383 in the soname of the shared library<footnote>
4384 The soname is the shared object name: it's the thing
4385 that has to match exactly between building an executable
4386 and running it for the dynamic linker to be able run the
4387 program. For example, if the soname of the library is
4388 <file>libfoo.so.6</file>, the library package would be
4389 called <file>libfoo6</file>.
4391 Alternatively, if it would be confusing to directly append
4392 <var>soversion</var> to <var>libraryname</var> (e.g. because
4393 <var>libraryname</var> itself ends in a number), you may use
4394 <package><var>libraryname</var>-<var>soversion</var></package> and
4395 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4399 If you have several shared libraries built from the same
4400 source tree you may lump them all together into a single
4401 shared library package, provided that you change all of
4402 their sonames at once (so that you don't get filename
4403 clashes if you try to install different versions of the
4404 combined shared libraries package).
4408 The package should install the shared libraries under
4409 their normal names. For example, the <package>libgdbm3</package>
4410 package should install <file>libgdbm.so.3.0.0</file> as
4411 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4412 renamed or re-linked by any <prgn>prerm</prgn> or
4413 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4414 of renaming things safely without affecting running programs,
4415 and attempts to interfere with this are likely to lead to
4420 Shared libraries should not be installed executable, since
4421 the dynamic linker does not require this and trying to
4422 execute a shared library usually results in a core dump.
4426 The run-time library package should include the symbolic link that
4427 <prgn>ldconfig</prgn> would create for the shared libraries.
4428 For example, the <package>libgdbm3</package> package should include
4429 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4430 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4431 linker (for example <prgn>ld.so</prgn> or
4432 <prgn>ld-linux.so.*</prgn>) can find the library between the
4433 time that <prgn>dpkg</prgn> installs it and the time that
4434 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4436 The package management system requires the library to be
4437 placed before the symbolic link pointing to it in the
4438 <file>.deb</file> file. This is so that when
4439 <prgn>dpkg</prgn> comes to install the symlink
4440 (overwriting the previous symlink pointing at an older
4441 version of the library), the new shared library is already
4442 in place. In the past, this was achieved by creating the
4443 library in the temporary packaging directory before
4444 creating the symlink. Unfortunately, this was not always
4445 effective, since the building of the tar file in the
4446 <file>.deb</file> depended on the behavior of the underlying
4447 file system. Some file systems (such as reiserfs) reorder
4448 the files so that the order of creation is forgotten.
4449 Since version 1.7.0, <prgn>dpkg</prgn>
4450 reorders the files itself as necessary when building a
4451 package. Thus it is no longer important to concern
4452 oneself with the order of file creation.
4456 <sect1 id="ldconfig">
4457 <heading><tt>ldconfig</tt></heading>
4460 Any package installing shared libraries in one of the default
4461 library directories of the dynamic linker (which are currently
4462 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4463 listed in <file>/etc/ld.so.conf</file><footnote>
4465 <list compact="compact">
4466 <item>/usr/X11R6/lib/Xaw3d</item>
4467 <item>/usr/local/lib</item>
4468 <item>/usr/lib/libc5-compat</item>
4469 <item>/lib/libc5-compat</item>
4470 <item>/usr/X11R6/lib</item>
4473 must use <prgn>ldconfig</prgn> to update the shared library
4478 The package must call <prgn>ldconfig</prgn> in the
4479 <prgn>postinst</prgn> script if the first argument is
4480 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4481 optionally invoke <prgn>ldconfig</prgn> at other times. The
4482 package should call <prgn>ldconfig</prgn> in the
4483 <prgn>postrm</prgn> script if the first argument is
4484 <tt>remove</tt>. The maintainer scripts must not invoke
4485 <prgn>ldconfig</prgn> under any circumstances other than those
4486 described in this paragraph.<footnote>
4488 During install or upgrade, the preinst is called before
4489 the new files are installed, so calling "ldconfig" is
4490 pointless. The preinst of an existing package can also be
4491 called if an upgrade fails. However, this happens during
4492 the critical time when a shared libs may exist on-disk
4493 under a temporary name. Thus, it is dangerous and
4494 forbidden by current policy to call "ldconfig" at this
4499 When a package is installed or upgraded, "postinst
4500 configure" runs after the new files are safely on-disk.
4501 Since it is perfectly safe to invoke ldconfig
4502 unconditionally in a postinst, it is OK for a package to
4503 simply put ldconfig in its postinst without checking the
4504 argument. The postinst can also be called to recover from
4505 a failed upgrade. This happens before any new files are
4506 unpacked, so there is no reason to call "ldconfig" at this
4511 For a package that is being removed, prerm is
4512 called with all the files intact, so calling ldconfig is
4513 useless. The other calls to "prerm" happen in the case of
4514 upgrade at a time when all the files of the old package
4515 are on-disk, so again calling "ldconfig" is pointless.
4519 postrm, on the other hand, is called with the "remove"
4520 argument just after the files are removed, so this is the
4521 proper time to call "ldconfig" to notify the system of the
4522 fact shared libraries from the package are removed.
4523 The postrm can be called at several other times. At the
4524 time of "postrm purge", "postrm abort-install", or "postrm
4525 abort-upgrade", calling "ldconfig" is useless because the
4526 shared lib files are not on-disk. However, when "postrm"
4527 is invoked with arguments "upgrade", "failed-upgrade", or
4528 "disappear", a shared lib may exist on-disk under a
4537 <sect id="sharedlibs-runtime-progs">
4538 <heading>Run-time support programs</heading>
4541 If your package has some run-time support programs which use
4542 the shared library you must not put them in the shared
4543 library package. If you do that then you won't be able to
4544 install several versions of the shared library without
4545 getting filename clashes.
4549 Instead, either create another package for the runtime binaries
4550 (this package might typically be named
4551 <package><var>libraryname</var>-runtime</package>; note the absence
4552 of the <var>soversion</var> in the package name), or if the
4553 development package is small, include them in there.
4557 <sect id="sharedlibs-static">
4558 <heading>Static libraries</heading>
4561 The static library (<file><var>libraryname.a</var></file>)
4562 is usually provided in addition to the shared version.
4563 It is placed into the development package (see below).
4567 In some cases, it is acceptable for a library to be
4568 available in static form only; these cases include:
4570 <item>libraries for languages whose shared library support
4571 is immature or unstable</item>
4572 <item>libraries whose interfaces are in flux or under
4573 development (commonly the case when the library's
4574 major version number is zero, or where the ABI breaks
4575 across patchlevels)</item>
4576 <item>libraries which are explicitly intended to be
4577 available only in static form by their upstream
4582 <sect id="sharedlibs-dev">
4583 <heading>Development files</heading>
4586 The development files associated to a shared library need to be
4587 placed in a package called
4588 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4589 or if you prefer only to support one development version at a
4590 time, <package><var>libraryname</var>-dev</package>.
4594 In case several development versions of a library exist, you may
4595 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4596 <ref id="conflicts">) to ensure that the user only installs one
4597 development version at a time (as different development versions are
4598 likely to have the same header files in them, which would cause a
4599 filename clash if both were installed).
4603 The development package should contain a symlink for the associated
4604 shared library without a version number. For example, the
4605 <package>libgdbm-dev</package> package should include a symlink
4606 from <file>/usr/lib/libgdbm.so</file> to
4607 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4608 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4609 <file>libgdbm.so</file> when compiling dynamically.
4613 <sect id="sharedlibs-intradeps">
4614 <heading>Dependencies between the packages of the same library</heading>
4617 Typically the development version should have an exact
4618 version dependency on the runtime library, to make sure that
4619 compilation and linking happens correctly. The
4620 <tt>${Source-Version}</tt> substitution variable can be
4621 useful for this purpose.
4625 <sect id="sharedlibs-shlibdeps">
4626 <heading>Dependencies between the library and other packages -
4627 the <tt>shlibs</tt> system</heading>
4630 If a package contains a binary or library which links to a
4631 shared library, we must ensure that when the package is
4632 installed on the system, all of the libraries needed are
4633 also installed. This requirement led to the creation of the
4634 <tt>shlibs</tt> system, which is very simple in its design:
4635 any package which <em>provides</em> a shared library also
4636 provides information on the package dependencies required to
4637 ensure the presence of this library, and any package which
4638 <em>uses</em> a shared library uses this information to
4639 determine the dependencies it requires. The files which
4640 contain the mapping from shared libraries to the necessary
4641 dependency information are called <file>shlibs</file> files.
4645 Thus, when a package is built which contains any shared
4646 libraries, it must provide a <file>shlibs</file> file for other
4647 packages to use, and when a package is built which contains
4648 any shared libraries or compiled binaries, it must run
4649 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4650 on these to determine the libraries used and hence the
4651 dependencies needed by this package.<footnote>
4653 In the past, the shared libraries linked to were
4654 determined by calling <prgn>ldd</prgn>, but now
4655 <prgn>objdump</prgn> is used to do this. The only
4656 change this makes to package building is that
4657 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4658 libraries, whereas in the past this was unnecessary.
4659 The rest of this footnote explains the advantage that
4664 We say that a binary <tt>foo</tt> <em>directly</em> uses
4665 a library <tt>libbar</tt> if it is explicitly linked
4666 with that library (that is, it uses the flag
4667 <tt>-lbar</tt> during the linking stage). Other
4668 libraries that are needed by <tt>libbar</tt> are linked
4669 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4670 linker will load them automatically when it loads
4671 <tt>libbar</tt>. A package should depend on
4672 the libraries it directly uses, and the dependencies for
4673 those libraries should automatically pull in the other
4678 Unfortunately, the <prgn>ldd</prgn> program shows both
4679 the directly and indirectly used libraries, meaning that
4680 the dependencies determined included both direct and
4681 indirect dependencies. The use of <prgn>objdump</prgn>
4682 avoids this problem by determining only the directly
4687 A good example of where this helps is the following. We
4688 could update <tt>libimlib</tt> with a new version that
4689 supports a new graphics format called dgf (but retaining
4690 the same major version number). If we used the old
4691 <prgn>ldd</prgn> method, every package that uses
4692 <tt>libimlib</tt> would need to be recompiled so it
4693 would also depend on <tt>libdgf</tt> or it wouldn't run
4694 due to missing symbols. However with the new system,
4695 packages using <tt>libimlib</tt> can rely on
4696 <tt>libimlib</tt> itself having the dependency on
4697 <tt>libdgf</tt> and so they would not need rebuilding.
4703 In the following sections, we will first describe where the
4704 various <tt>shlibs</tt> files are to be found, then how to
4705 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4706 file format and how to create them if your package contains a
4711 <heading>The <tt>shlibs</tt> files present on the system</heading>
4714 There are several places where <tt>shlibs</tt> files are
4715 found. The following list gives them in the order in which
4717 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4718 (The first one which gives the required information is used.)
4724 <p><file>debian/shlibs.local</file></p>
4727 This lists overrides for this package. Its use is
4728 described below (see <ref id="shlibslocal">).
4733 <p><file>/etc/dpkg/shlibs.override</file></p>
4736 This lists global overrides. This list is normally
4737 empty. It is maintained by the local system
4743 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4746 When packages are being built, any
4747 <file>debian/shlibs</file> files are copied into the
4748 control file area of the temporary build directory and
4749 given the name <file>shlibs</file>. These files give
4750 details of any shared libraries included in the
4752 An example may help here. Let us say that the
4753 source package <tt>foo</tt> generates two binary
4754 packages, <tt>libfoo2</tt> and
4755 <tt>foo-runtime</tt>. When building the binary
4756 packages, the two packages are created in the
4757 directories <file>debian/libfoo2</file> and
4758 <file>debian/foo-runtime</file> respectively.
4759 (<file>debian/tmp</file> could be used instead of one
4760 of these.) Since <tt>libfoo2</tt> provides the
4761 <tt>libfoo</tt> shared library, it will require a
4762 <tt>shlibs</tt> file, which will be installed in
4763 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4765 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4766 when <prgn>dpkg-shlibdeps</prgn> is run on the
4768 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4770 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4771 determine whether <tt>foo-prog</tt>'s library
4772 dependencies are satisfied by any of the libraries
4773 provided by <tt>libfoo2</tt>. For this reason,
4774 <prgn>dpkg-shlibdeps</prgn> must only be run once
4775 all of the individual binary packages'
4776 <tt>shlibs</tt> files have been installed into the
4783 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4786 These are the <file>shlibs</file> files corresponding to
4787 all of the packages installed on the system, and are
4788 maintained by the relevant package maintainers.
4793 <p><file>/etc/dpkg/shlibs.default</file></p>
4796 This file lists any shared libraries whose packages
4797 have failed to provide correct <file>shlibs</file> files.
4798 It was used when the <file>shlibs</file> setup was first
4799 introduced, but it is now normally empty. It is
4800 maintained by the <tt>dpkg</tt> maintainer.
4808 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4809 <file>shlibs</file> files</heading>
4813 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4814 into your <file>debian/rules</file> file. If your package
4815 contains only compiled binaries and libraries (but no scripts),
4816 you can use a command such as:
4817 <example compact="compact">
4818 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4819 debian/tmp/usr/lib/*
4821 Otherwise, you will need to explicitly list the compiled
4822 binaries and libraries.<footnote>
4823 If you are using <tt>debhelper</tt>, the
4824 <prgn>dh_shlibdeps</prgn> program will do this work for
4825 you. It will also correctly handle multi-binary
4831 This command puts the dependency information into the
4832 <file>debian/substvars</file> file, which is then used by
4833 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4834 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4835 field in the control file for this to work.
4839 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4840 done. If it does complain you might need to create your own
4841 <file>debian/shlibs.local</file> file, as explained below (see
4842 <ref id="shlibslocal">).
4846 If you have multiple binary packages, you will need to call
4847 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4848 compiled libraries or binaries. In such a case, you will
4849 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4850 utilities to specify a different <file>substvars</file> file.
4854 For more details on dpkg-shlibdeps, please see
4855 <ref id="pkg-dpkg-shlibdeps"> and
4856 <manref name="dpkg-shlibdeps" section="1">.
4861 <heading>The <file>shlibs</file> File Format</heading>
4864 Each <file>shlibs</file> file has the same format. Lines
4865 beginning with <tt>#</tt> are considered to be comments and
4866 are ignored. Each line is of the form:
4867 <example compact="compact">
4868 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4873 We will explain this by reference to the example of the
4874 <tt>zlib1g</tt> package, which (at the time of writing)
4875 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4879 <var>library-name</var> is the name of the shared library,
4880 in this case <tt>libz</tt>. (This must match the name part
4881 of the soname, see below.)
4885 <var>soname-version-number</var> is the version part of the
4886 soname of the library. The soname is the thing that must
4887 exactly match for the library to be recognized by the
4888 dynamic linker, and is usually of the form
4889 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4890 example, <tt>libz.so.1</tt>.<footnote>
4891 This can be determined using the command
4892 <example compact="compact">
4893 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4896 The version part is the part which comes after
4897 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4901 <var>dependencies</var> has the same syntax as a dependency
4902 field in a binary package control file. It should give
4903 details of which packages are required to satisfy a binary
4904 built against the version of the library contained in the
4905 package. See <ref id="depsyntax"> for details.
4909 In our example, if the first version of the <tt>zlib1g</tt>
4910 package which contained a minor number of at least
4911 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4912 <tt>shlibs</tt> entry for this library could say:
4913 <example compact="compact">
4914 libz 1 zlib1g (>= 1:1.1.3)
4916 The version-specific dependency is to avoid warnings from
4917 the dynamic linker about using older shared libraries with
4923 <heading>Providing a <file>shlibs</file> file</heading>
4926 If your package provides a shared library, you should create
4927 a <file>shlibs</file> file following the format described above.
4928 It is usual to call this file <file>debian/shlibs</file> (but if
4929 you have multiple binary packages, you might want to call it
4930 <file>debian/shlibs.<var>package</var></file> instead). Then
4931 let <file>debian/rules</file> install it in the control area:
4932 <example compact="compact">
4933 install -m644 debian/shlibs debian/tmp/DEBIAN
4935 or, in the case of a multi-binary package:
4936 <example compact="compact">
4937 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4939 An alternative way of doing this is to create the
4940 <file>shlibs</file> file in the control area directly from
4941 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4942 file at all,<footnote>
4943 This is what <prgn>dh_makeshlibs</prgn> in the
4944 <tt>debhelper</tt> suite does.
4946 since the <file>debian/shlibs</file> file itself is ignored by
4947 <prgn>dpkg-shlibdeps</prgn>.
4951 As <prgn>dpkg-shlibdeps</prgn> reads the
4952 <file>DEBIAN/shlibs</file> files in all of the binary packages
4953 being built from this source package, all of the
4954 <file>DEBIAN/shlibs</file> files should be installed before
4955 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4960 <sect1 id="shlibslocal">
4961 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4964 This file is intended only as a <em>temporary</em> fix if
4965 your binaries or libraries depend on a library whose package
4966 does not yet provide a correct <file>shlibs</file> file.
4970 We will assume that you are trying to package a binary
4971 <tt>foo</tt>. When you try running
4972 <prgn>dpkg-shlibdeps</prgn> you get the following error
4973 message (<tt>-O</tt> displays the dependency information on
4974 <tt>stdout</tt> instead of writing it to
4975 <tt>debian/substvars</tt>, and the lines have been wrapped
4976 for ease of reading):
4977 <example compact="compact">
4978 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4979 dpkg-shlibdeps: warning: unable to find dependency
4980 information for shared library libbar (soname 1,
4981 path /usr/lib/libbar.so.1, dependency field Depends)
4982 shlibs:Depends=libc6 (>= 2.2.2-2)
4984 You can then run <prgn>ldd</prgn> on the binary to find the
4985 full location of the library concerned:
4986 <example compact="compact">
4988 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4989 libc.so.6 => /lib/libc.so.6 (0x40032000)
4990 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4992 So the <prgn>foo</prgn> binary depends on the
4993 <prgn>libbar</prgn> shared library, but no package seems to
4994 provide a <file>*.shlibs</file> file handling
4995 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4996 determine the package responsible:
4997 <example compact="compact">
4998 $ dpkg -S /usr/lib/libbar.so.1
4999 bar1: /usr/lib/libbar.so.1
5000 $ dpkg -s bar1 | grep Version
5003 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5004 is the one we are using. Now we can file a bug against the
5005 <tt>bar1</tt> package and create our own
5006 <file>debian/shlibs.local</file> to locally fix the problem.
5007 Including the following line into your
5008 <file>debian/shlibs.local</file> file:
5009 <example compact="compact">
5010 libbar 1 bar1 (>= 1.0-1)
5012 should allow the package build to work.
5016 As soon as the maintainer of <tt>bar1</tt> provides a
5017 correct <file>shlibs</file> file, you should remove this line
5018 from your <file>debian/shlibs.local</file> file. (You should
5019 probably also then have a versioned <tt>Build-Depends</tt>
5020 on <tt>bar1</tt> to help ensure that others do not have the
5021 same problem building your package.)
5030 <chapt id="opersys"><heading>The Operating System</heading>
5033 <heading>Filesystem hierarchy</heading>
5037 <heading>Filesystem Structure</heading>
5040 The location of all installed files and directories must
5041 comply with the Filesystem Hierarchy Standard (FHS),
5042 version 2.1, except where doing so would violate other
5043 terms of Debian Policy. The version of this document
5044 referred here can be found in the <tt>debian-policy</tt>
5046 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5047 name="FHS (Debian copy)"> alongside this manual (or, if
5048 you have the <package>debian-policy</package> installed,
5050 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5051 (local copy)">). The
5052 latest version, which may be a more recent version, may
5054 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5055 Specific questions about following the standard may be
5056 asked on the <tt>debian-devel</tt> mailing list, or
5057 referred to the FHS mailing list (see the
5058 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5064 <heading>Site-specific programs</heading>
5067 As mandated by the FHS, packages must not place any
5068 files in <file>/usr/local</file>, either by putting them in
5069 the file system archive to be unpacked by <prgn>dpkg</prgn>
5070 or by manipulating them in their maintainer scripts.
5074 However, the package may create empty directories below
5075 <file>/usr/local</file> so that the system administrator knows
5076 where to place site-specific files. These directories
5077 should be removed on package removal if they are
5082 Note, that this applies only to directories <em>below</em>
5083 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5084 Packages must not create sub-directories in the directory
5085 <file>/usr/local</file> itself, except those listed in FHS,
5086 section 4.5. However, you may create directories below
5087 them as you wish. You must not remove any of the
5088 directories listed in 4.5, even if you created them.
5092 Since <file>/usr/local</file> can be mounted read-only from a
5093 remote server, these directories must be created and
5094 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5095 maintainer scripts and not be included in the
5096 <file>.deb</file> archive. These scripts must not fail if
5097 either of these operations fail.
5101 For example, the <tt>emacsen-common</tt> package could
5102 contain something like
5103 <example compact="compact">
5104 if [ ! -e /usr/local/share/emacs ]
5106 if mkdir /usr/local/share/emacs 2>/dev/null
5108 chown root:staff /usr/local/share/emacs
5109 chmod 2775 /usr/local/share/emacs
5113 in its <prgn>postinst</prgn> script, and
5114 <example compact="compact">
5115 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5116 rmdir /usr/local/share/emacs 2>/dev/null || true
5118 in the <prgn>prerm</prgn> script. (Note that this form is
5119 used to ensure that if the script is interrupted, the
5120 directory <file>/usr/local/share/emacs</file> will still be
5125 If you do create a directory in <file>/usr/local</file> for
5126 local additions to a package, you should ensure that
5127 settings in <file>/usr/local</file> take precedence over the
5128 equivalents in <file>/usr</file>.
5132 However, because <file>/usr/local</file> and its contents are
5133 for exclusive use of the local administrator, a package
5134 must not rely on the presence or absence of files or
5135 directories in <file>/usr/local</file> for normal operation.
5139 The <file>/usr/local</file> directory itself and all the
5140 subdirectories created by the package should (by default) have
5141 permissions 2775 (group-writable and set-group-id) and be
5142 owned by <tt>root.staff</tt>.
5147 <heading>The system-wide mail directory</heading>
5149 The system-wide mail directory is <file>/var/mail</file>. This
5150 directory is part of the base system and should not owned
5151 by any particular mail agents. The use of the old
5152 location <file>/var/spool/mail</file> is deprecated, even
5153 though the spool may still be physically located there.
5154 To maintain partial upgrade compatibility for systems
5155 which have <file>/var/spool/mail</file> as their physical mail
5156 spool, packages using <file>/var/mail</file> must depend on
5157 either <package>libc6</package> (>= 2.1.3-13), or on
5158 <package>base-files</package> (>= 2.2.0), or on later
5159 versions of either one of these packages.
5165 <heading>Users and groups</heading>
5168 <heading>Introduction</heading>
5170 The Debian system can be configured to use either plain or
5175 Some user ids (UIDs) and group ids (GIDs) are reserved
5176 globally for use by certain packages. Because some
5177 packages need to include files which are owned by these
5178 users or groups, or need the ids compiled into binaries,
5179 these ids must be used on any Debian system only for the
5180 purpose for which they are allocated. This is a serious
5181 restriction, and we should avoid getting in the way of
5182 local administration policies. In particular, many sites
5183 allocate users and/or local system groups starting at 100.
5187 Apart from this we should have dynamically allocated ids,
5188 which should by default be arranged in some sensible
5189 order, but the behavior should be configurable.
5193 Packages other than <tt>base-passwd</tt> must not modify
5194 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5195 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5200 <heading>UID and GID classes</heading>
5202 The UID and GID numbers are divided into classes as
5208 Globally allocated by the Debian project, the same
5209 on every Debian system. These ids will appear in
5210 the <file>passwd</file> and <file>group</file> files of all
5211 Debian systems, new ids in this range being added
5212 automatically as the <tt>base-passwd</tt> package is
5217 Packages which need a single statically allocated
5218 uid or gid should use one of these; their
5219 maintainers should ask the <tt>base-passwd</tt>
5227 Dynamically allocated system users and groups.
5228 Packages which need a user or group, but can have
5229 this user or group allocated dynamically and
5230 differently on each system, should use <tt>adduser
5231 --system</tt> to create the group and/or user.
5232 <prgn>adduser</prgn> will check for the existence of
5233 the user or group, and if necessary choose an unused
5234 id based on the ranges specified in
5235 <file>adduser.conf</file>.
5239 <tag>1000-29999:</tag>
5242 Dynamically allocated user accounts. By default
5243 <prgn>adduser</prgn> will choose UIDs and GIDs for
5244 user accounts in this range, though
5245 <file>adduser.conf</file> may be used to modify this
5250 <tag>30000-59999:</tag>
5255 <tag>60000-64999:</tag>
5258 Globally allocated by the Debian project, but only
5259 created on demand. The ids are allocated centrally
5260 and statically, but the actual accounts are only
5261 created on users' systems on demand.
5265 These ids are for packages which are obscure or
5266 which require many statically-allocated ids. These
5267 packages should check for and create the accounts in
5268 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5269 <prgn>adduser</prgn> if it has this facility) if
5270 necessary. Packages which are likely to require
5271 further allocations should have a "hole" left after
5272 them in the allocation, to give them room to
5277 <tag>65000-65533:</tag>
5285 User <tt>nobody</tt>. The corresponding gid refers
5286 to the group <tt>nogroup</tt>.
5293 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5294 not</em> be used, because it is the error return
5303 <sect id="sysvinit">
5304 <heading>System run levels and <file>init.d</file> scripts</heading>
5306 <sect1 id="/etc/init.d">
5307 <heading>Introduction</heading>
5310 The <file>/etc/init.d</file> directory contains the scripts
5311 executed by <prgn>init</prgn> at boot time and when the
5312 init state (or "runlevel") is changed (see <manref
5313 name="init" section="8">).
5317 There are at least two different, yet functionally
5318 equivalent, ways of handling these scripts. For the sake
5319 of simplicity, this document describes only the symbolic
5320 link method. However, it must not be assumed by maintainer
5321 scripts that this method is being used, and any automated
5322 manipulation of the various runlevel behaviours by
5323 maintainer scripts must be performed using
5324 <prgn>update-rc.d</prgn> as described below and not by
5325 manually installing or removing symlinks. For information
5326 on the implementation details of the other method,
5327 implemented in the <tt>file-rc</tt> package, please refer
5328 to the documentation of that package.
5332 These scripts are referenced by symbolic links in the
5333 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5334 runlevels, <prgn>init</prgn> looks in the directory
5335 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5336 execute, where <tt><var>n</var></tt> is the runlevel that
5337 is being changed to, or <tt>S</tt> for the boot-up
5342 The names of the links all have the form
5343 <file>S<var>mm</var><var>script</var></file> or
5344 <file>K<var>mm</var><var>script</var></file> where
5345 <var>mm</var> is a two-digit number and <var>script</var>
5346 is the name of the script (this should be the same as the
5347 name of the actual script in <file>/etc/init.d</file>).
5351 When <prgn>init</prgn> changes runlevel first the targets
5352 of the links whose names start with a <tt>K</tt> are
5353 executed, each with the single argument <tt>stop</tt>,
5354 followed by the scripts prefixed with an <tt>S</tt>, each
5355 with the single argument <tt>start</tt>. (The links are
5356 those in the <file>/etc/rc<var>n</var>.d</file> directory
5357 corresponding to the new runlevel.) The <tt>K</tt> links
5358 are responsible for killing services and the <tt>S</tt>
5359 link for starting services upon entering the runlevel.
5363 For example, if we are changing from runlevel 2 to
5364 runlevel 3, init will first execute all of the <tt>K</tt>
5365 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5366 all of the <tt>S</tt> prefixed scripts in that directory.
5367 The links starting with <tt>K</tt> will cause the
5368 referred-to file to be executed with an argument of
5369 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5374 The two-digit number <var>mm</var> is used to determine
5375 the order in which to run the scripts: low-numbered links
5376 have their scripts run first. For example, the
5377 <tt>K20</tt> scripts will be executed before the
5378 <tt>K30</tt> scripts. This is used when a certain service
5379 must be started before another. For example, the name
5380 server <prgn>bind</prgn> might need to be started before
5381 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5382 can set up its access lists. In this case, the script
5383 that starts <prgn>bind</prgn> would have a lower number
5384 than the script that starts <prgn>inn</prgn> so that it
5386 <example compact="compact">
5393 The two runlevels 0 (halt) and 6 (reboot) are slightly
5394 different. In these runlevels, the links with an
5395 <tt>S</tt> prefix are still called after those with a
5396 <tt>K</tt> prefix, but they too are called with the single
5397 argument <tt>stop</tt>.
5401 Also, if the script name ends <tt>.sh</tt>, the script
5402 will be sourced in runlevel <tt>S</tt> rather that being
5403 run in a forked subprocess, but will be explicitly run by
5404 <prgn>sh</prgn> in all other runlevels.
5409 <heading>Writing the scripts</heading>
5412 Packages that include daemons for system services should
5413 place scripts in <file>/etc/init.d</file> to start or stop
5414 services at boot time or during a change of runlevel.
5415 These scripts should be named
5416 <file>/etc/init.d/<var>package</var></file>, and they should
5417 accept one argument, saying what to do:
5420 <tag><tt>start</tt></tag>
5421 <item>start the service,</item>
5423 <tag><tt>stop</tt></tag>
5424 <item>stop the service,</item>
5426 <tag><tt>restart</tt></tag>
5427 <item>stop and restart the service if it's already running,
5428 otherwise start the service</item>
5430 <tag><tt>reload</tt></tag>
5431 <item><p>cause the configuration of the service to be
5432 reloaded without actually stopping and restarting
5435 <tag><tt>force-reload</tt></tag>
5436 <item>cause the configuration to be reloaded if the
5437 service supports this, otherwise restart the
5441 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5442 <tt>force-reload</tt> options should be supported by all
5443 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5448 The <file>init.d</file> scripts should ensure that they will
5449 behave sensibly if invoked with <tt>start</tt> when the
5450 service is already running, or with <tt>stop</tt> when it
5451 isn't, and that they don't kill unfortunately-named user
5452 processes. The best way to achieve this is usually to use
5453 <prgn>start-stop-daemon</prgn>.
5457 If a service reloads its configuration automatically (as
5458 in the case of <prgn>cron</prgn>, for example), the
5459 <tt>reload</tt> option of the <file>init.d</file> script
5460 should behave as if the configuration has been reloaded
5465 The <file>/etc/init.d</file> scripts must be treated as
5466 configuration files, either (if they are present in the
5467 package, that is, in the .deb file) by marking them as
5468 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5469 by managing them correctly in the maintainer scripts (see
5470 <ref id="config-files">). This is important since we want
5471 to give the local system administrator the chance to adapt
5472 the scripts to the local system, e.g., to disable a
5473 service without de-installing the package, or to specify
5474 some special command line options when starting a service,
5475 while making sure their changes aren't lost during the next
5480 These scripts should not fail obscurely when the
5481 configuration files remain but the package has been
5482 removed, as configuration files remain on the system after
5483 the package has been removed. Only when <prgn>dpkg</prgn>
5484 is executed with the <tt>--purge</tt> option will
5485 configuration files be removed. In particular, as the
5486 <file>/etc/init.d/<var>package</var></file> script itself is
5487 usually a <tt>conffile</tt>, it will remain on the system
5488 if the package is removed but not purged. Therefore, you
5489 should include a <tt>test</tt> statement at the top of the
5491 <example compact="compact">
5492 test -f <var>program-executed-later-in-script</var> || exit 0
5497 Often there are some variables in the <file>init.d</file>
5498 scripts whose values control the behaviour of the scripts,
5499 and which a system administrator is likely to want to
5500 change. As the scripts themselves are frequently
5501 <tt>conffile</tt>s, modifying them requires that the
5502 administrator merge in their changes each time the package
5503 is upgraded and the <tt>conffile</tt> changes. To ease
5504 the burden on the system administrator, such configurable
5505 values should not be placed directly in the script.
5506 Instead, they should be placed in a file in
5507 <file>/etc/default</file>, which typically will have the same
5508 base name as the <file>init.d</file> script. This extra file
5509 should be sourced by the script when the script runs. It
5510 must contain only variable settings and comments in POSIX
5511 <prgn>sh</prgn> format. It may either be a
5512 <tt>conffile</tt> or a configuration file maintained by
5513 the package maintainer scripts. See <ref id="config-files">
5518 To ensure that vital configurable values are always
5519 available, the <file>init.d</file> script should set default
5520 values for each of the shell variables it uses, either
5521 before sourcing the <file>/etc/default/</file> file or
5522 afterwards using something like the <tt>:
5523 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5524 script must behave sensibly and not fail if the
5525 <file>/etc/default</file> file is deleted.
5530 <heading>Interfacing with the initscript system</heading>
5533 Maintainers should use the abstraction layer provided by
5534 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5535 programs to deal with initscripts in their packages'
5536 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5537 and <prgn>postrm</prgn>.
5541 Directly managing the /etc/rc?.d links and directly
5542 invoking the <file>/etc/init.d/</file> initscripts should
5543 be done only by packages providing the initscript
5544 subsystem (such as <prgn>sysv-rc</prgn> and
5545 <prgn>file-rc</prgn>).
5549 <heading>Managing the links</heading>
5552 The program <prgn>update-rc.d</prgn> is provided for
5553 package maintainers to arrange for the proper creation and
5554 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5555 or their functional equivalent if another method is being
5556 used. This may be used by maintainers in their packages'
5557 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5561 You must not include any <file>/etc/rc<var>n</var>.d</file>
5562 symbolic links in the actual archive or manually create or
5563 remove the symbolic links in maintainer scripts; you must
5564 use the <prgn>update-rc.d</prgn> program instead. (The
5565 former will fail if an alternative method of maintaining
5566 runlevel information is being used.) You must not include
5567 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5568 in the archive either. (Only the <tt>sysvinit</tt>
5573 By default <prgn>update-rc.d</prgn> will start services in
5574 each of the multi-user state runlevels (2, 3, 4, and 5)
5575 and stop them in the halt runlevel (0), the single-user
5576 runlevel (1) and the reboot runlevel (6). The system
5577 administrator will have the opportunity to customize
5578 runlevels by simply adding, moving, or removing the
5579 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5580 symbolic links are being used, or by modifying
5581 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5586 To get the default behavior for your package, put in your
5587 <prgn>postinst</prgn> script
5588 <example compact="compact">
5589 update-rc.d <var>package</var> defaults
5591 and in your <prgn>postrm</prgn>
5592 <example compact="compact">
5593 if [ "$1" = purge ]; then
5594 update-rc.d <var>package</var> remove
5596 </example>. Note that if your package changes runlevels
5597 or priority, you may have to remove and recreate the links,
5598 since otherwise the old links may persist. Refer to the
5599 documentation of <prgn>update-rc.d</prgn>.
5603 This will use a default sequence number of 20. If it does
5604 not matter when or in which order the <file>init.d</file>
5605 script is run, use this default. If it does, then you
5606 should talk to the maintainer of the <prgn>sysvinit</prgn>
5607 package or post to <tt>debian-devel</tt>, and they will
5608 help you choose a number.
5612 For more information about using <tt>update-rc.d</tt>,
5613 please consult its man page <manref name="update-rc.d"
5619 <heading>Running initscripts</heading>
5621 The program <prgn>invoke-rc.d</prgn> is provided to make
5622 it easier for package maintainers to properly invoke an
5623 initscript, obeying runlevel and other locally-defined
5624 constraints that might limit a package's right to start,
5625 stop and otherwise manage services. This program may be
5626 used by maintainers in their packages' scripts.
5630 The use of <prgn>invoke-rc.d</prgn> to invoke the
5631 <file>/etc/init.d/*</file> initscripts is strongly
5632 recommended<footnote>
5633 In the future, the use of invoke-rc.d to invoke
5634 initscripts shall be made mandatory. Maintainers are
5635 advised to switch to invoke-rc.d as soon as
5637 </footnote>, instead of calling them directly.
5641 By default, <prgn>invoke-rc.d</prgn> will pass any
5642 action requests (start, stop, reload, restart...) to the
5643 <file>/etc/init.d</file> script, filtering out requests
5644 to start or restart a service out of its intended
5649 Most packages will simply need to change:
5650 <example compact="compact">/etc/init.d/<package>
5651 <action></example> in their <prgn>postinst</prgn>
5652 and <prgn>prerm</prgn> scripts to:
5653 <example compact="compact">
5654 if which invoke-rc.d >/dev/null 2>&1; then
5655 invoke-rc.d <var>package</var> <action>
5657 /etc/init.d/<var>package</var> <action>
5663 A package should register its initscript services using
5664 <prgn>update-rc.d</prgn> before it tries to invoke them
5665 using <prgn>invoke-rc.d</prgn>. Invocation of
5666 unregistered services may fail.
5670 For more information about using
5671 <prgn>invoke-rc.d</prgn>, please consult its man page
5672 <manref name="invoke-rc.d" section="8">.
5678 <heading>Boot-time initialization</heading>
5681 There used to be another directory, <file>/etc/rc.boot</file>,
5682 which contained scripts which were run once per machine
5683 boot. This has been deprecated in favour of links from
5684 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5685 described in <ref id="/etc/init.d">. Packages must not
5686 place files in <file>/etc/rc.boot</file>.
5691 <heading>Example</heading>
5694 The <prgn>bind</prgn> DNS (nameserver) package wants to
5695 make sure that the nameserver is running in multiuser
5696 runlevels, and is properly shut down with the system. It
5697 puts a script in <file>/etc/init.d</file>, naming the script
5698 appropriately <tt>bind</tt>. As you can see, the script
5699 interprets the argument <tt>reload</tt> to send the
5700 nameserver a <tt>HUP</tt> signal (causing it to reload its
5701 configuration); this way the system administrator can say
5702 <tt>/etc/init.d/bind reload</tt> to reload the name
5703 server. The script has one configurable value, which can
5704 be used to pass parameters to the named program at
5705 startup; this value is read from
5706 <file>/etc/default/bind</file> (see below).
5710 <example compact="compact">
5713 # Original version by Robert Leslie
5714 # <rob@mars.org>, edited by iwj and cs
5716 test -x /usr/sbin/named || exit 0
5718 # Source defaults file.
5720 if [ -f /etc/default/bind ]; then
5727 echo -n "Starting domain name service: named"
5728 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5733 echo -n "Stopping domain name service: named"
5734 start-stop-daemon --stop --quiet \
5735 --pidfile /var/run/named.pid --exec /usr/sbin/named
5739 echo -n "Restarting domain name service: named"
5740 start-stop-daemon --stop --quiet --oknodo \
5741 --pidfile /var/run/named.pid --exec /usr/sbin/named
5742 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5746 force-reload|reload)
5747 echo -n "Reloading configuration of domain name service: named"
5748 start-stop-daemon --stop --signal 1 --quiet \
5749 --pidfile /var/run/named.pid --exec /usr/sbin/named
5753 echo "Usage: /etc/init.d/bind " \
5754 " {start|stop|restart|reload|force-reload}" >&2
5764 Complementing the above init script is a configuration
5765 file <file>/etc/default/bind</file>, which contains
5766 configurable parameters used by the script. This would be
5767 created by the <prgn>postinst</prgn> script if it was not
5768 already present, and removed on purge by the
5769 <prgn>postrm</prgn> script.
5770 <example compact="compact">
5771 # Specified parameters to pass to named. See named(8).
5772 # You may uncomment the following line, and edit to taste.
5778 Another example on which you can base your
5779 <file>/etc/init.d</file> scripts is found in
5780 <file>/etc/init.d/skeleton</file>.
5784 If this package is happy with the default setup from
5785 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5786 and having named running in all runlevels, it can say in
5787 its <prgn>postinst</prgn>:
5788 <example compact="compact">
5789 update-rc.d bind defaults >/dev/null
5791 And in its <prgn>postrm</prgn>, to remove the links when the
5793 <example compact="compact">
5794 if [ "$1" = purge ]; then
5795 update-rc.d bind remove >/dev/null
5803 <heading>Console messages from <file>init.d</file> scripts</heading>
5806 This section describes the formats to be used for messages
5807 written to standard output by the <file>/etc/init.d</file>
5808 scripts. The intent is to improve the consistency of
5809 Debian's startup and shutdown look and feel. For this
5810 reason, please look very carefully at the details. We want
5811 the messages to have the same format in terms of wording,
5812 spaces, punctuation and case of letters.
5816 Here is a list of overall rules that should be used for
5817 messages generated by <file>/etc/init.d</file> scripts.
5823 The message should fit in one line (fewer than 80
5824 characters), start with a capital letter and end with
5825 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5829 If the script is performing some time consuming task in
5830 the background (not merely starting or stopping a
5831 program, for instance), an ellipsis (three dots:
5832 <tt>...</tt>) should be output to the screen, with no
5833 leading or tailing whitespace or line feeds.
5837 The messages should appear as if the computer is telling
5838 the user what it is doing (politely :-), but should not
5839 mention "it" directly. For example, instead of:
5840 <example compact="compact">
5841 I'm starting network daemons: nfsd mountd.
5843 the message should say
5844 <example compact="compact">
5845 Starting network daemons: nfsd mountd.
5852 <tt>init.d</tt> script should use the following standard
5853 message formats for the situations enumerated below.
5859 <p>When daemons are started</p>
5862 If the script starts one or more daemons, the output
5863 should look like this (a single line, no leading
5865 <example compact="compact">
5866 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5868 The <var>description</var> should describe the
5869 subsystem the daemon or set of daemons are part of,
5870 while <var>daemon-1</var> up to <var>daemon-n</var>
5871 denote each daemon's name (typically the file name of
5876 For example, the output of <file>/etc/init.d/lpd</file>
5878 <example compact="compact">
5879 Starting printer spooler: lpd.
5884 This can be achieved by saying
5885 <example compact="compact">
5886 echo -n "Starting printer spooler: lpd"
5887 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5890 in the script. If there are more than one daemon to
5891 start, the output should look like this:
5892 <example compact="compact">
5893 echo -n "Starting remote file system services:"
5894 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5895 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5896 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5899 This makes it possible for the user to see what is
5900 happening and when the final daemon has been started.
5901 Care should be taken in the placement of white spaces:
5902 in the example above the system administrators can
5903 easily comment out a line if they don't want to start
5904 a specific daemon, while the displayed message still
5910 <p>When a system parameter is being set</p>
5913 If you have to set up different system parameters
5914 during the system boot, you should use this format:
5915 <example compact="compact">
5916 Setting <var>parameter</var> to "<var>value</var>".
5921 You can use a statement such as the following to get
5923 <example compact="compact">
5924 echo "Setting DNS domainname to \"$domainname\"."
5929 Note that the same symbol (<tt>"</tt>) is used for the left
5930 and right quotation marks. A grave accent (<tt>`</tt>) is
5931 not a quote character; neither is an apostrophe
5937 <p>When a daemon is stopped or restarted</p>
5940 When you stop or restart a daemon, you should issue a
5941 message identical to the startup message, except that
5942 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5943 or <tt>Restarting</tt> respectively.
5947 For example, stopping the printer daemon will like
5949 <example compact="compact">
5950 Stopping printer spooler: lpd.
5956 <p>When something is executed</p>
5959 There are several examples where you have to run a
5960 program at system startup or shutdown to perform a
5961 specific task, for example, setting the system's clock
5962 using <prgn>netdate</prgn> or killing all processes
5963 when the system shuts down. Your message should look
5965 <example compact="compact">
5966 Doing something very useful...done.
5968 You should print the <tt>done.</tt> immediately after
5969 the job has been completed, so that the user is
5970 informed why they have to wait. You can get this
5972 <example compact="compact">
5973 echo -n "Doing something very useful..."
5982 <p>When the configuration is reloaded</p>
5985 When a daemon is forced to reload its configuration
5986 files you should use the following format:
5987 <example compact="compact">
5988 Reloading <var>description</var> configuration...done.
5990 where <var>description</var> is the same as in the
5991 daemon starting message.
5999 <heading>Cron jobs</heading>
6002 Packages must not modify the configuration file
6003 <file>/etc/crontab</file>, and they must not modify the files in
6004 <file>/var/spool/cron/crontabs</file>.</p>
6007 If a package wants to install a job that has to be executed
6008 via cron, it should place a file with the name of the
6009 package in one or more of the following directories:
6010 <example compact="compact">
6015 As these directory names imply, the files within them are
6016 executed on a daily, weekly, or monthly basis,
6017 respectively. The exact times are listed in
6018 <file>/etc/crontab</file>.</p>
6021 All files installed in any of these directories must be
6022 scripts (e.g., shell scripts or Perl scripts) so that they
6023 can easily be modified by the local system administrator.
6024 In addition, they should be treated as configuration
6029 If a certain job has to be executed more frequently than
6030 daily, the package should install a file
6031 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6032 same syntax as <file>/etc/crontab</file> and is processed by
6033 <prgn>cron</prgn> automatically. The file must also be
6034 treated as a configuration file. (Note that entries in the
6035 <file>/etc/cron.d</file> directory are not handled by
6036 <prgn>anacron</prgn>. Thus, you should only use this
6037 directory for jobs which may be skipped if the system is not
6041 The scripts or crontab entries in these directories should
6042 check if all necessary programs are installed before they
6043 try to execute them. Otherwise, problems will arise when a
6044 package was removed but not purged since configuration files
6045 are kept on the system in this situation.</p>
6049 <heading>Menus</heading>
6052 The Debian <tt>menu</tt> package provides a standard
6053 interface between packages providing applications and
6054 <em>menu programs</em> (either X window managers or
6055 text-based menu programs such as <prgn>pdmenu</prgn>).
6059 All packages that provide applications that need not be
6060 passed any special command line arguments for normal
6061 operation should register a menu entry for those
6062 applications, so that users of the <tt>menu</tt> package
6063 will automatically get menu entries in their window
6064 managers, as well in shells like <tt>pdmenu</tt>.
6068 Menu entries should follow the current menu policy.
6072 The menu policy can be found in the <tt>menu-policy</tt>
6073 files in the <tt>debian-policy</tt> package.
6074 It is also available from the Debian web mirrors at
6075 <tt><url name="/doc/packaging-manuals/menu-policy/"
6076 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6080 Please also refer to the <em>Debian Menu System</em>
6081 documentation that comes with the <package>menu</package>
6082 package for information about how to register your
6088 <heading>Multimedia handlers</heading>
6091 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6092 is a mechanism for encoding files and data streams and
6093 providing meta-information about them, in particular their
6094 type (e.g. audio or video) and format (e.g. PNG, HTML,
6099 Registration of MIME type handlers allows programs like mail
6100 user agents and web browsers to invoke these handlers to
6101 view, edit or display MIME types they don't support directly.
6105 Packages which provide the ability to view/show/play,
6106 compose, edit or print MIME types should register themselves
6107 as such following the current MIME support policy.
6111 The MIME support policy can be found in the <tt>mime-policy</tt>
6112 files in the <tt>debian-policy</tt> package.
6113 It is also available from the Debian web mirrors at
6114 <tt><url name="/doc/packaging-manuals/mime-policy/"
6115 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6121 <heading>Keyboard configuration</heading>
6124 To achieve a consistent keyboard configuration so that all
6125 applications interpret a keyboard event the same way, all
6126 programs in the Debian distribution must be configured to
6127 comply with the following guidelines.
6131 The following keys must have the specified interpretations:
6134 <tag><tt><--</tt></tag>
6135 <item>delete the character to the left of the cursor</item>
6137 <tag><tt>Delete</tt></tag>
6138 <item>delete the character to the right of the cursor</item>
6140 <tag><tt>Control+H</tt></tag>
6141 <item>emacs: the help prefix</item>
6144 The interpretation of any keyboard events should be
6145 independent of the terminal that is used, be it a virtual
6146 console, an X terminal emulator, an rlogin/telnet session,
6151 The following list explains how the different programs
6152 should be set up to achieve this:
6158 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6162 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6166 X translations are set up to make
6167 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6168 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6169 is the vt220 escape code for the "delete character"
6170 key). This must be done by loading the X resources
6171 using <prgn>xrdb</prgn> on all local X displays, not
6172 using the application defaults, so that the
6173 translation resources used correspond to the
6174 <prgn>xmodmap</prgn> settings.
6178 The Linux console is configured to make
6179 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6180 generate <tt>ESC [ 3 ~</tt>.
6184 X applications are configured so that <tt><</tt>
6185 deletes left, and <tt>Delete</tt> deletes right. Motif
6186 applications already work like this.
6190 Terminals should have <tt>stty erase ^?</tt> .
6194 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6195 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6196 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6200 Emacs is programmed to map <tt>KB_Backspace</tt> or
6201 the <tt>stty erase</tt> character to
6202 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6203 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6204 <tt>^H</tt> to <tt>help</tt> as always.
6208 Other applications use the <tt>stty erase</tt>
6209 character and <tt>kdch1</tt> for the two delete keys,
6210 with ASCII DEL being "delete previous character" and
6211 <tt>kdch1</tt> being "delete character under
6219 This will solve the problem except for the following
6226 Some terminals have a <tt><--</tt> key that cannot
6227 be made to produce anything except <tt>^H</tt>. On
6228 these terminals Emacs help will be unavailable on
6229 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6230 character takes precedence in Emacs, and has been set
6231 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6232 available) can be used instead.
6236 Some operating systems use <tt>^H</tt> for <tt>stty
6237 erase</tt>. However, modern telnet versions and all
6238 rlogin versions propagate <tt>stty</tt> settings, and
6239 almost all UNIX versions honour <tt>stty erase</tt>.
6240 Where the <tt>stty</tt> settings are not propagated
6241 correctly, things can be made to work by using
6242 <tt>stty</tt> manually.
6246 Some systems (including previous Debian versions) use
6247 <prgn>xmodmap</prgn> to arrange for both
6248 <tt><--</tt> and <tt>Delete</tt> to generate
6249 <tt>KB_Delete</tt>. We can change the behavior of
6250 their X clients using the same X resources that we use
6251 to do it for our own clients, or configure our clients
6252 using their resources when things are the other way
6253 around. On displays configured like this
6254 <tt>Delete</tt> will not work, but <tt><--</tt>
6259 Some operating systems have different <tt>kdch1</tt>
6260 settings in their <tt>terminfo</tt> database for
6261 <tt>xterm</tt> and others. On these systems the
6262 <tt>Delete</tt> key will not work correctly when you
6263 log in from a system conforming to our policy, but
6264 <tt><--</tt> will.
6271 <heading>Environment variables</heading>
6274 A program must not depend on environment variables to get
6275 reasonable defaults. (That's because these environment
6276 variables would have to be set in a system-wide
6277 configuration file like <file>/etc/profile</file>, which is not
6278 supported by all shells.)
6282 If a program usually depends on environment variables for its
6283 configuration, the program should be changed to fall back to
6284 a reasonable default configuration if these environment
6285 variables are not present. If this cannot be done easily
6286 (e.g., if the source code of a non-free program is not
6287 available), the program must be replaced by a small
6288 "wrapper" shell script which sets the environment variables
6289 if they are not already defined, and calls the original program.
6293 Here is an example of a wrapper script for this purpose:
6295 <example compact="compact">
6297 BAR=${BAR:-/var/lib/fubar}
6299 exec /usr/lib/foo/foo "$@"
6304 Furthermore, as <file>/etc/profile</file> is a configuration
6305 file of the <prgn>base-files</prgn> package, other packages must
6306 not put any environment variables or other commands into that
6311 <sect id="doc-base">
6312 <heading>Registering Documents using doc-base</heading>
6315 The <package>doc-base</package> package implements a
6316 flexible mechanism for handling and presenting
6317 documentation. The recommended practice is for every Debian
6318 package that provides online documentation (other than just
6319 manual pages) to register these documents with
6320 <package>doc-base</package> by installing a
6321 <package>doc-base</package> control file via the
6322 <prgn/install-docs/ script at installation time and
6323 de-register the manuals again when the package is removed.
6326 Please refer to the documentation that comes with the
6327 <package>doc-base</package> package for information and
6336 <heading>Files</heading>
6339 <heading>Binaries</heading>
6342 Two different packages must not install programs with
6343 different functionality but with the same filenames. (The
6344 case of two programs having the same functionality but
6345 different implementations is handled via "alternatives" or
6346 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6347 <ref id="conflicts"> respectively.) If this case happens,
6348 one of the programs must be renamed. The maintainers should
6349 report this to the <tt>debian-devel</tt> mailing list and
6350 try to find a consensus about which program will have to be
6351 renamed. If a consensus cannot be reached, <em>both</em>
6352 programs must be renamed.
6356 By default, when a package is being built, any binaries
6357 created should include debugging information, as well as
6358 being compiled with optimization. You should also turn on
6359 as many reasonable compilation warnings as possible; this
6360 makes life easier for porters, who can then look at build
6361 logs for possible problems. For the C programming language,
6362 this means the following compilation parameters should be
6364 <example compact="compact">
6366 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6368 install -s # (or use strip on the files in debian/tmp)
6373 Note that by default all installed binaries should be stripped,
6374 either by using the <tt>-s</tt> flag to
6375 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6376 the binaries after they have been copied into
6377 <file>debian/tmp</file> but before the tree is made into a
6382 Although binaries in the build tree should be compiled with
6383 debugging information by default, it can often be difficult
6384 to debug programs if they are also subjected to compiler
6385 optimization. For this reason, it is recommended to support
6386 the standardized environment
6387 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6388 contain several flags to change how a package is compiled
6396 The presence of this string means that the package
6397 should be compiled with a minimum of optimization.
6398 For C programs, it is best to add <tt>-O0</tt>
6399 to <tt>CFLAGS</tt> (although this is usually the
6400 default). Some programs might fail to build or run at
6401 this level of optimization; it may be necessary to
6402 use <tt>-O1</tt>, for example.
6406 This string means that the debugging symbols should
6407 not be stripped from the binary during installation,
6408 so that debugging information may be included in the package.
6414 The following makefile snippet is an example of how one may
6415 implement the build options; you will probably have to
6416 massage this example in order to make it work for your
6418 <example compact="compact">
6421 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6422 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6423 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6424 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6426 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6431 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6432 INSTALL_PROGRAM += -s
6438 It is up to the package maintainer to decide what
6439 compilation options are best for the package. Certain
6440 binaries (such as computationally-intensive programs) will
6441 function better with certain flags (<tt>-O3</tt>, for
6442 example); feel free to use them. Please use good judgment
6443 here. Don't use flags for the sake of it; only use them
6444 if there is good reason to do so. Feel free to override
6445 the upstream author's ideas about which compilation
6446 options are best: they are often inappropriate for our
6452 <sect id="libraries">
6453 <heading>Libraries</heading>
6456 The shared version of a library must be compiled with
6457 <tt>-fPIC</tt>, and the static version must not be. In other
6458 words, each source unit (<tt>*.c</tt>, for example, for C files)
6459 will need to be compiled twice.
6463 You must specify the gcc option <tt>-D_REENTRANT</tt>
6464 when building a library (either static or shared) to make
6465 the library compatible with LinuxThreads.
6469 Although not enforced by the build tools, shared libraries
6470 must be linked against all libraries that they use symbols from
6471 in the same way that binaries are. This ensures the correct
6472 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6473 system and guarantees that all libraries can be safely opened
6474 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6475 option <tt>-Wl,-z,defs</tt> when building a shared library.
6476 Since this option enforces symbol resolution at build time,
6477 a missing library reference will be caught early as a fatal
6482 All installed shared libraries should be stripped with
6483 <example compact="compact">
6484 strip --strip-unneeded <var>your-lib</var>
6486 (The option <tt>--strip-unneeded</tt> makes
6487 <prgn>strip</prgn> remove only the symbols which aren't
6488 needed for relocation processing.) Shared libraries can
6489 function perfectly well when stripped, since the symbols for
6490 dynamic linking are in a separate part of the ELF object
6492 You might also want to use the options
6493 <tt>--remove-section=.comment</tt> and
6494 <tt>--remove-section=.note</tt> on both shared libraries
6495 and executables, and <tt>--strip-debug</tt> on static
6501 Note that under some circumstances it may be useful to
6502 install a shared library unstripped, for example when
6503 building a separate package to support debugging.
6507 Shared object files (often <file>.so</file> files) that are not
6508 public libraries, that is, they are not meant to be linked
6509 to by third party executables (binaries of other packages),
6510 should be installed in subdirectories of the
6511 <file>/usr/lib</file> directory. Such files are exempt from the
6512 rules that govern ordinary shared libraries, except that
6513 they must not be installed executable and should be
6515 A common example are the so-called "plug-ins",
6516 internal shared objects that are dynamically loaded by
6517 programs using <manref name="dlopen" section="3">.
6522 Packages containing shared libraries that may be linked to
6523 by other packages' binaries, but which for some
6524 <em>compelling</em> reason can not be installed in
6525 <file>/usr/lib</file> directory, may install the shared library
6526 files in subdirectories of the <file>/usr/lib</file> directory,
6527 in which case they should arrange to add that directory in
6528 <file>/etc/ld.so.conf</file> in the package's post-installation
6529 script, and remove it in the package's post-removal script.
6533 An ever increasing number of packages are using
6534 <prgn>libtool</prgn> to do their linking. The latest GNU
6535 libtools (>= 1.3a) can take advantage of the metadata in the
6536 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6537 files). The main advantage of <prgn>libtool</prgn>'s
6538 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6539 store and subsequently access metadata with respect to the
6540 libraries it builds. <prgn>libtool</prgn> will search for
6541 those files, which contain a lot of useful information about
6542 a library (such as library dependency information for static
6543 linking). Also, they're <em>essential</em> for programs
6544 using <tt>libltdl</tt>.<footnote>
6545 Although <prgn>libtool</prgn> is fully capable of
6546 linking against shared libraries which don't have
6547 <tt>.la</tt> files, as it is a mere shell script it can
6548 add considerably to the build time of a
6549 <prgn>libtool</prgn>-using package if that shell script
6550 has to derive all this information from first principles
6551 for each library every time it is linked. With the
6552 advent of <prgn>libtool</prgn> version 1.4 (and to a
6553 lesser extent <prgn>libtool</prgn> version 1.3), the
6554 <file>.la</file> files also store information about
6555 inter-library dependencies which cannot necessarily be
6556 derived after the <file>.la</file> file is deleted.
6561 Packages that use <prgn>libtool</prgn> to create shared
6562 libraries should include the <file>.la</file> files in the
6563 <tt>-dev</tt> package, unless the package relies on
6564 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6565 the <tt>.la</tt> files must go in the run-time library
6570 You must make sure that you use only released versions of
6571 shared libraries to build your packages; otherwise other
6572 users will not be able to run your binaries
6573 properly. Producing source packages that depend on
6574 unreleased compilers is also usually a bad
6581 <heading>Shared libraries</heading>
6583 This section has moved to <ref id="sharedlibs">.
6589 <heading>Scripts</heading>
6592 All command scripts, including the package maintainer
6593 scripts inside the package and used by <prgn>dpkg</prgn>,
6594 should have a <tt>#!</tt> line naming the shell to be used
6599 In the case of Perl scripts this should be
6600 <tt>#!/usr/bin/perl</tt>.
6604 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6605 should almost certainly start with <tt>set -e</tt> so that
6606 errors are detected. Every script should use
6607 <tt>set -e</tt> or check the exit status of <em>every</em>
6612 The standard shell interpreter <file>/bin/sh</file> can be a
6613 symbolic link to any POSIX compatible shell, if <tt>echo
6614 -n</tt> does not generate a newline.<footnote>
6615 Debian policy specifies POSIX behavior for
6616 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6617 use in the Linux community (in particular including this
6618 policy, the Linux kernel source, many Debian scripts,
6619 etc.). This <tt>echo -n</tt> mechanism is valid but not
6620 required under POSIX, hence this explicit addition.
6621 Also, rumour has it that this shall be mandated under
6624 Thus, shell scripts specifying <file>/bin/sh</file> as
6625 interpreter should only use POSIX features. If a script
6626 requires non-POSIX features from the shell interpreter, the
6627 appropriate shell must be specified in the first line of the
6628 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6629 depend on the package providing the shell (unless the shell
6630 package is marked "Essential", as in the case of
6635 You may wish to restrict your script to POSIX features when
6636 possible so that it may use <file>/bin/sh</file> as its
6637 interpreter. If your script works with <prgn>dash</prgn>
6638 (originally called <prgn>ash</prgn>), it's probably POSIX
6639 compliant, but if you are in doubt, use
6640 <file>/bin/bash</file>.
6644 Perl scripts should check for errors when making any
6645 system calls, including <tt>open</tt>, <tt>print</tt>,
6646 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6650 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6651 scripting languages. See <em>Csh Programming Considered
6652 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6653 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
6654 If an upstream package comes with <prgn>csh</prgn> scripts
6655 then you must make sure that they start with
6656 <tt>#!/bin/csh</tt> and make your package depend on the
6657 <prgn>c-shell</prgn> virtual package.
6661 Any scripts which create files in world-writeable
6662 directories (e.g., in <file>/tmp</file>) must use a
6663 mechanism which will fail if a file with the same name
6668 The Debian base system provides the <prgn>tempfile</prgn>
6669 and <prgn>mktemp</prgn> utilities for use by scripts for
6676 <heading>Symbolic links</heading>
6679 In general, symbolic links within a top-level directory
6680 should be relative, and symbolic links pointing from one
6681 top-level directory into another should be absolute. (A
6682 top-level directory is a sub-directory of the root
6683 directory <file>/</file>.)
6687 In addition, symbolic links should be specified as short as
6688 possible, i.e., link targets like <file>foo/../bar</file> are
6693 Note that when creating a relative link using
6694 <prgn>ln</prgn> it is not necessary for the target of the
6695 link to exist relative to the working directory you're
6696 running <prgn>ln</prgn> from, nor is it necessary to change
6697 directory to the directory where the link is to be made.
6698 Simply include the string that should appear as the target
6699 of the link (this will be a pathname relative to the
6700 directory in which the link resides) as the first argument
6705 For example, in your <prgn>Makefile</prgn> or
6706 <file>debian/rules</file>, you can do things like:
6707 <example compact="compact">
6708 ln -fs gcc $(prefix)/bin/cc
6709 ln -fs gcc debian/tmp/usr/bin/cc
6710 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6711 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6716 A symbolic link pointing to a compressed file should always
6717 have the same file extension as the referenced file. (For
6718 example, if a file <file>foo.gz</file> is referenced by a
6719 symbolic link, the filename of the link has to end with
6720 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6725 <heading>Device files</heading>
6728 Packages must not include device files in the package file
6733 If a package needs any special device files that are not
6734 included in the base system, it must call
6735 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6736 after notifying the user<footnote>
6737 This notification could be done via a (low-priority)
6738 debconf message, or an echo (printf) statement.
6743 Packages must not remove any device files in the
6744 <prgn>postrm</prgn> or any other script. This is left to the
6745 system administrator.
6749 Debian uses the serial devices
6750 <file>/dev/ttyS*</file>. Programs using the old
6751 <file>/dev/cu*</file> devices should be changed to use
6752 <file>/dev/ttyS*</file>.
6756 <sect id="config-files">
6757 <heading>Configuration files</heading>
6760 <heading>Definitions</heading>
6764 <tag>configuration file</tag>
6766 A file that affects the operation of a program, or
6767 provides site- or host-specific information, or
6768 otherwise customizes the behavior of a program.
6769 Typically, configuration files are intended to be
6770 modified by the system administrator (if needed or
6771 desired) to conform to local policy or to provide
6772 more useful site-specific behavior.
6775 <tag><tt>conffile</tt></tag>
6777 A file listed in a package's <tt>conffiles</tt>
6778 file, and is treated specially by <prgn>dpkg</prgn>
6779 (see <ref id="configdetails">).
6785 The distinction between these two is important; they are
6786 not interchangeable concepts. Almost all
6787 <tt>conffile</tt>s are configuration files, but many
6788 configuration files are not <tt>conffiles</tt>.
6792 Note that a script that embeds configuration information
6793 (such as most of the files in <file>/etc/default</file> and
6794 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6795 configuration file and should be treated as such.
6800 <heading>Location</heading>
6803 Any configuration files created or used by your package
6804 must reside in <file>/etc</file>. If there are several,
6805 consider creating a subdirectory of <file>/etc</file>
6806 named after your package.
6810 If your package creates or uses configuration files
6811 outside of <file>/etc</file>, and it is not feasible to modify
6812 the package to use <file>/etc</file> directly, put the files
6813 in <file>/etc</file> and create symbolic links to those files
6814 from the location that the package requires.
6819 <heading>Behavior</heading>
6822 Configuration file handling must conform to the following
6824 <list compact="compact">
6826 local changes must be preserved during a package
6830 configuration files must be preserved when the
6831 package is removed, and only deleted when the
6838 The easy way to achieve this behavior is to make the
6839 configuration file a <tt>conffile</tt>. This is
6840 appropriate only if it is possible to distribute a default
6841 version that will work for most installations, although
6842 some system administrators may choose to modify it. This
6843 implies that the default version will be part of the
6844 package distribution, and must not be modified by the
6845 maintainer scripts during installation (or at any other
6850 In order to ensure that local changes are preserved
6851 correctly, no package may contain or make hard links to
6852 conffiles.<footnote>
6853 Rationale: There are two problems with hard links.
6854 The first is that some editors break the link while
6855 editing one of the files, so that the two files may
6856 unwittingly become unlinked and different. The second
6857 is that <prgn>dpkg</prgn> might break the hard link
6858 while upgrading <tt>conffile</tt>s.
6863 The other way to do it is via the maintainer scripts. In
6864 this case, the configuration file must not be listed as a
6865 <tt>conffile</tt> and must not be part of the package
6866 distribution. If the existence of a file is required for
6867 the package to be sensibly configured it is the
6868 responsibility of the package maintainer to provide
6869 maintainer scripts which correctly create, update and
6870 maintain the file and remove it on purge. (See <ref
6871 id="maintainerscripts"> for more information.) These
6872 scripts must be idempotent (i.e., must work correctly if
6873 <prgn>dpkg</prgn> needs to re-run them due to errors
6874 during installation or removal), must cope with all the
6875 variety of ways <prgn>dpkg</prgn> can call maintainer
6876 scripts, must not overwrite or otherwise mangle the user's
6877 configuration without asking, must not ask unnecessary
6878 questions (particularly during upgrades), and otherwise be
6883 The scripts are not required to configure every possible
6884 option for the package, but only those necessary to get
6885 the package running on a given system. Ideally the
6886 sysadmin should not have to do any configuration other
6887 than that done (semi-)automatically by the
6888 <prgn>postinst</prgn> script.
6892 A common practice is to create a script called
6893 <file><var>package</var>-configure</file> and have the
6894 package's <prgn>postinst</prgn> call it if and only if the
6895 configuration file does not already exist. In certain
6896 cases it is useful for there to be an example or template
6897 file which the maintainer scripts use. Such files should
6898 be in <file>/usr/share/<var>package</var></file> or
6899 <file>/usr/lib/<var>package</var></file> (depending on whether
6900 they are architecture-independent or not). There should
6901 be symbolic links to them from
6902 <file>/usr/share/doc/<var>package</var>/examples</file> if
6903 they are examples, and should be perfectly ordinary
6904 <prgn>dpkg</prgn>-handled files (<em>not</em>
6905 configuration files).
6909 These two styles of configuration file handling must
6910 not be mixed, for that way lies madness:
6911 <prgn>dpkg</prgn> will ask about overwriting the file
6912 every time the package is upgraded.
6917 <heading>Sharing configuration files</heading>
6920 Packages which specify the same file as a
6921 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6922 with each other. (This is an instance of the general rule
6923 about not sharing files. Note that neither alternatives
6924 nor diversions are likely to be appropriate in this case;
6925 in particular, <prgn>dpkg</prgn> does not handle diverted
6926 <tt>conffile</tt>s well.)
6930 The maintainer scripts must not alter a <tt>conffile</tt>
6931 of <em>any</em> package, including the one the scripts
6936 If two or more packages use the same configuration file
6937 and it is reasonable for both to be installed at the same
6938 time, one of these packages must be defined as
6939 <em>owner</em> of the configuration file, i.e., it will be
6940 the package which handles that file as a configuration
6941 file. Other packages that use the configuration file must
6942 depend on the owning package if they require the
6943 configuration file to operate. If the other package will
6944 use the configuration file if present, but is capable of
6945 operating without it, no dependency need be declared.
6949 If it is desirable for two or more related packages to
6950 share a configuration file <em>and</em> for all of the
6951 related packages to be able to modify that configuration
6952 file, then the following should be done:
6953 <enumlist compact="compact">
6955 One of the related packages (the "owning" package)
6956 will manage the configuration file with maintainer
6957 scripts as described in the previous section.
6960 The owning package should also provide a program
6961 that the other packages may use to modify the
6965 The related packages must use the provided program
6966 to make any desired modifications to the
6967 configuration file. They should either depend on
6968 the core package to guarantee that the configuration
6969 modifier program is available or accept gracefully
6970 that they cannot modify the configuration file if it
6971 is not. (This is in addition to the fact that the
6972 configuration file may not even be present in the
6979 Sometimes it's appropriate to create a new package which
6980 provides the basic infrastructure for the other packages
6981 and which manages the shared configuration files. (The
6982 <tt>sgml-base</tt> package is a good example.)
6987 <heading>User configuration files ("dotfiles")</heading>
6990 The files in <file>/etc/skel</file> will automatically be
6991 copied into new user accounts by <prgn>adduser</prgn>.
6992 No other program should reference the files in
6993 <file>/etc/skel</file>.
6997 Therefore, if a program needs a dotfile to exist in
6998 advance in <file>$HOME</file> to work sensibly, that dotfile
6999 should be installed in <file>/etc/skel</file> and treated as a
7004 However, programs that require dotfiles in order to
7005 operate sensibly are a bad thing, unless they do create
7006 the dotfiles themselves automatically.
7010 Furthermore, programs should be configured by the Debian
7011 default installation to behave as closely to the upstream
7012 default behaviour as possible.
7016 Therefore, if a program in a Debian package needs to be
7017 configured in some way in order to operate sensibly, that
7018 should be done using a site-wide configuration file placed
7019 in <file>/etc</file>. Only if the program doesn't support a
7020 site-wide default configuration and the package maintainer
7021 doesn't have time to add it may a default per-user file be
7022 placed in <file>/etc/skel</file>.
7026 <file>/etc/skel</file> should be as empty as we can make it.
7027 This is particularly true because there is no easy (or
7028 necessarily desirable) mechanism for ensuring that the
7029 appropriate dotfiles are copied into the accounts of
7030 existing users when a package is installed.
7036 <heading>Log files</heading>
7038 Log files should usually be named
7039 <file>/var/log/<var>package</var>.log</file>. If you have many
7040 log files, or need a separate directory for permission
7041 reasons (<file>/var/log</file> is writable only by
7042 <file>root</file>), you should usually create a directory named
7043 <file>/var/log/<var>package</var></file> and place your log
7048 Log files must be rotated occasionally so that they don't
7049 grow indefinitely; the best way to do this is to drop a log
7050 rotation configuration file into the directory
7051 <file>/etc/logrotate.d</file> and use the facilities provided by
7052 logrotate.<footnote>
7054 The traditional approach to log files has been to set up
7055 <em>ad hoc</em> log rotation schemes using simple shell
7056 scripts and cron. While this approach is highly
7057 customizable, it requires quite a lot of sysadmin work.
7058 Even though the original Debian system helped a little
7059 by automatically installing a system which can be used
7060 as a template, this was deemed not enough.
7064 The use of <prgn>logrotate</prgn>, a program developed
7065 by Red Hat, is better, as it centralizes log management.
7066 It has both a configuration file
7067 (<file>/etc/logrotate.conf</file>) and a directory where
7068 packages can drop their individual log rotation
7069 configurations (<file>/etc/logrotate.d</file>).
7072 Here is a good example for a logrotate config
7073 file (for more information see <manref name="logrotate"
7075 <example compact="compact">
7076 /var/log/foo/*.log {
7081 /etc/init.d/foo force-reload
7085 This rotates all files under <file>/var/log/foo</file>, saves 12
7086 compressed generations, and forces the daemon to reload its
7087 configuration information after the log rotation.
7091 Log files should be removed when the package is
7092 purged (but not when it is only removed). This should be
7093 done by the <prgn>postrm</prgn> script when it is called
7094 with the argument <tt>purge</tt> (see <ref
7095 id="removedetails">).
7100 <heading>Permissions and owners</heading>
7103 The rules in this section are guidelines for general use.
7104 If necessary you may deviate from the details below.
7105 However, if you do so you must make sure that what is done
7106 is secure and you should try to be as consistent as possible
7107 with the rest of the system. You should probably also
7108 discuss it on <prgn>debian-devel</prgn> first.
7112 Files should be owned by <tt>root.root</tt>, and made
7113 writable only by the owner and universally readable (and
7114 executable, if appropriate), that is mode 644 or 755.
7118 Directories should be mode 755 or (for group-writability)
7119 mode 2775. The ownership of the directory should be
7120 consistent with its mode: if a directory is mode 2775, it
7121 should be owned by the group that needs write access to
7126 Setuid and setgid executables should be mode 4755 or 2755
7127 respectively, and owned by the appropriate user or group.
7128 They should not be made unreadable (modes like 4711 or
7129 2711 or even 4111); doing so achieves no extra security,
7130 because anyone can find the binary in the freely available
7131 Debian package; it is merely inconvenient. For the same
7132 reason you should not restrict read or execute permissions
7133 on non-set-id executables.
7137 Some setuid programs need to be restricted to particular
7138 sets of users, using file permissions. In this case they
7139 should be owned by the uid to which they are set-id, and by
7140 the group which should be allowed to execute them. They
7141 should have mode 4754; again there is no point in making
7142 them unreadable to those users who must not be allowed to
7147 It is possible to arrange that the system administrator can
7148 reconfigure the package to correspond to their local
7149 security policy by changing the permissions on a binary:
7150 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7151 described below.<footnote>
7152 Ordinary files installed by <prgn>dpkg</prgn> (as
7153 opposed to <tt>conffile</tt>s and other similar objects)
7154 normally have their permissions reset to the distributed
7155 permissions when the package is reinstalled. However,
7156 the use of <prgn>dpkg-statoverride</prgn> overrides this
7157 default behaviour. If you use this method, you should
7158 remember to describe <prgn>dpkg-statoverride</prgn> in
7159 the package documentation; being a relatively new
7160 addition to Debian, it is probably not yet well-known.
7162 Another method you should consider is to create a group for
7163 people allowed to use the program(s) and make any setuid
7164 executables executable only by that group.
7168 If you need to create a new user or group for your package
7169 there are two possibilities. Firstly, you may need to
7170 make some files in the binary package be owned by this
7171 user or group, or you may need to compile the user or
7172 group id (rather than just the name) into the binary
7173 (though this latter should be avoided if possible, as in
7174 this case you need a statically allocated id).</p>
7177 If you need a statically allocated id, you must ask for a
7178 user or group id from the <tt>base-passwd</tt> maintainer,
7179 and must not release the package until you have been
7180 allocated one. Once you have been allocated one you must
7181 either make the package depend on a version of the
7182 <tt>base-passwd</tt> package with the id present in
7183 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7184 your package to create the user or group itself with the
7185 correct id (using <tt>adduser</tt>) in its
7186 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7187 the <prgn>postinst</prgn> is to be preferred if it is
7188 possible, otherwise a pre-dependency will be needed on the
7189 <tt>adduser</tt> package.)
7193 On the other hand, the program might be able to determine
7194 the uid or gid from the user or group name at runtime, so
7195 that a dynamically allocated id can be used. In this case
7196 you should choose an appropriate user or group name,
7197 discussing this on <prgn>debian-devel</prgn> and checking
7198 with the <package/base-passwd/ maintainer that it is unique and that
7199 they do not wish you to use a statically allocated id
7200 instead. When this has been checked you must arrange for
7201 your package to create the user or group if necessary using
7202 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7203 <prgn>postinst</prgn> script (again, the latter is to be
7204 preferred if it is possible).
7208 Note that changing the numeric value of an id associated
7209 with a name is very difficult, and involves searching the
7210 file system for all appropriate files. You need to think
7211 carefully whether a static or dynamic id is required, since
7212 changing your mind later will cause problems.
7215 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7217 This section is not intended as policy, but as a
7218 description of the use of <prgn>dpkg-statoverride</prgn>.
7222 <prgn>dpkg-statoverride</prgn> is a replacement for the
7223 deprecated <tt>suidmanager</tt> package. Packages which
7224 previously used <tt>suidmanager</tt> should have a
7225 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7226 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7227 and <tt>suidunregister</tt> should now be simply removed
7228 from the maintainer scripts.
7232 If a system administrator wishes to have a file (or
7233 directory or other such thing) installed with owner and
7234 permissions different from those in the distributed Debian
7235 package, they can use the <prgn>dpkg-statoverride</prgn>
7236 program to instruct <prgn>dpkg</prgn> to use the different
7237 settings every time the file is installed. Thus the
7238 package maintainer should distribute the files with their
7239 normal permissions, and leave it for the system
7240 administrator to make any desired changes. For example, a
7241 daemon which is normally required to be setuid root, but
7242 in certain situations could be used without being setuid,
7243 should be installed setuid in the <tt>.deb</tt>. Then the
7244 local system administrator can change this if they wish.
7245 If there are two standard ways of doing it, the package
7246 maintainer can use <tt>debconf</tt> to find out the
7247 preference, and call <prgn>dpkg-statoverride</prgn> in the
7248 maintainer script if necessary to accommodate the system
7249 administrator's choice.
7253 Given the above, <prgn>dpkg-statoverride</prgn> is
7254 essentially a tool for system administrators and would not
7255 normally be needed in the maintainer scripts. There is
7256 one type of situation, though, where calls to
7257 <prgn>dpkg-statoverride</prgn> would be needed in the
7258 maintainer scripts, and that involves packages which use
7259 dynamically allocated user or group ids. In such a
7260 situation, something like the following idiom can be very
7261 helpful in the package's <prgn>postinst</prgn>, where
7262 <tt>sysuser</tt> is a dynamically allocated id:
7264 for i in /usr/bin/foo /usr/sbin/bar
7266 if ! dpkg-statoverride --list $i >/dev/null
7268 dpkg-statoverride --update --add sysuser root 4755 $i
7272 The corresponding <tt>dpkg-statoverride --remove</tt>
7273 calls can then be made unconditionally when the package is
7281 <chapt id="customized-programs">
7282 <heading>Customized programs</heading>
7284 <sect id="arch-spec">
7285 <heading>Architecture specification strings</heading>
7288 If a program needs to specify an <em>architecture specification
7289 string</em> in some place, the following format should be
7290 used: <var>arch</var>-<var>os</var><footnote>
7291 The following architectures and operating systems are
7292 currently recognised by <prgn>dpkg-architecture</prgn>.
7293 The architecture, <tt><var>arch</var></tt>, is one of
7294 the following: <tt>alpha</tt>, <tt>arm</tt>,
7295 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7296 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7297 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7298 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7299 operating system, <tt><var>os</var></tt>, is one of:
7300 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7301 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7302 reserved for the GNU/Hurd operating system.
7307 Note that we don't want to use
7308 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7309 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7310 since this would make our programs incompatible with other
7311 Linux distributions. We also don't use something like
7312 <tt><var>arch</var>-unknown-linux</tt>, since the
7313 <tt>unknown</tt> does not look very good.
7318 <heading>Daemons</heading>
7321 The configuration files <file>/etc/services</file>,
7322 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7323 by the <prgn>netbase</prgn> package and must not be modified
7328 If a package requires a new entry in one of these files, the
7329 maintainer should get in contact with the
7330 <prgn>netbase</prgn> maintainer, who will add the entries
7331 and release a new version of the <prgn>netbase</prgn>
7336 The configuration file <file>/etc/inetd.conf</file> must not be
7337 modified by the package's scripts except via the
7338 <prgn>update-inetd</prgn> script or the
7339 <file>DebianNet.pm</file> Perl module. See their documentation
7340 for details on how to add entries.
7344 If a package wants to install an example entry into
7345 <file>/etc/inetd.conf</file>, the entry must be preceded with
7346 exactly one hash character (<tt>#</tt>). Such lines are
7347 treated as "commented out by user" by the
7348 <prgn>update-inetd</prgn> script and are not changed or
7349 activated during package updates.
7354 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7358 Some programs need to create pseudo-ttys. This should be done
7359 using Unix98 ptys if the C library supports it. The resulting
7360 program must not be installed setuid root, unless that
7361 is required for other functionality.
7365 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7366 <file>/var/log/lastlog</file> must be installed writeable by
7367 group <tt>utmp</tt>. Programs which need to modify those
7368 files must be installed setgid <tt>utmp</tt>.
7373 <heading>Editors and pagers</heading>
7376 Some programs have the ability to launch an editor or pager
7377 program to edit or display a text document. Since there are
7378 lots of different editors and pagers available in the Debian
7379 distribution, the system administrator and each user should
7380 have the possibility to choose their preferred editor and
7385 In addition, every program should choose a good default
7386 editor/pager if none is selected by the user or system
7391 Thus, every program that launches an editor or pager must
7392 use the EDITOR or PAGER environment variable to determine
7393 the editor or pager the user wishes to use. If these
7394 variables are not set, the programs <file>/usr/bin/editor</file>
7395 and <file>/usr/bin/pager</file> should be used, respectively.
7399 These two files are managed through the <prgn>dpkg</prgn>
7400 "alternatives" mechanism. Thus every package providing an
7401 editor or pager must call the
7402 <prgn>update-alternatives</prgn> script to register these
7407 If it is very hard to adapt a program to make use of the
7408 EDITOR or PAGER variables, that program may be configured to
7409 use <file>/usr/bin/sensible-editor</file> and
7410 <file>/usr/bin/sensible-pager</file> as the editor or pager
7411 program respectively. These are two scripts provided in the
7412 Debian base system that check the EDITOR and PAGER variables
7413 and launch the appropriate program, and fall back to
7414 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7415 variable is not set.
7419 A program may also use the VISUAL environment variable to
7420 determine the user's choice of editor. If it exists, it
7421 should take precedence over EDITOR. This is in fact what
7422 <file>/usr/bin/sensible-editor</file> does.
7426 It is not required for a package to depend on
7427 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7428 package to provide such virtual packages.<footnote>
7429 The Debian base system already provides an editor and a
7435 <sect id="web-appl">
7436 <heading>Web servers and applications</heading>
7439 This section describes the locations and URLs that should
7440 be used by all web servers and web applications in the
7447 Cgi-bin executable files are installed in the
7449 <example compact="compact">
7450 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7452 and should be referred to as
7453 <example compact="compact">
7454 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7459 <p>Access to HTML documents</p>
7462 HTML documents for a package are stored in
7463 <file>/usr/share/doc/<var>package</var></file>
7464 and can be referred to as
7465 <example compact="compact">
7466 http://localhost/doc/<var>package</var>/<var>filename</var>
7471 The web server should restrict access to the document
7472 tree so that only clients on the same host can read
7473 the documents. If the web server does not support such
7474 access controls, then it should not provide access at
7475 all, or ask about providing access during installation.
7480 <p>Web Document Root</p>
7483 Web Applications should try to avoid storing files in
7484 the Web Document Root. Instead they should use the
7485 /usr/share/doc/<var>package</var> directory for
7486 documents and register the Web Application via the
7487 <package>doc-base</package> package. If access to the
7488 web document root is unavoidable then use
7489 <example compact="compact">
7492 as the Document Root. This might be just a symbolic
7493 link to the location where the system administrator
7494 has put the real document root.
7502 <sect id="mail-transport-agents">
7503 <heading>Mail transport, delivery and user agents</heading>
7506 Debian packages which process electronic mail, whether mail
7507 user agents (MUAs) or mail transport agents (MTAs), must
7508 ensure that they are compatible with the configuration
7509 decisions below. Failure to do this may result in lost
7510 mail, broken <tt>From:</tt> lines, and other serious brain
7515 The mail spool is <file>/var/mail</file> and the interface to
7516 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7517 the FHS). On older systems, the mail spool may be
7518 physically located in <file>/var/spool/mail</file>, but all
7519 access to the mail spool should be via the
7520 <file>/var/mail</file> symlink. The mail spool is part of the
7521 base system and not part of the MTA package.
7525 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7526 programs (such as IMAP daemons) must lock the mailbox in an
7527 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7528 be combined with dot locking. To avoid deadlocks, a program
7529 should use <tt>fcntl()</tt> first and dot locking after
7530 this, or alternatively implement the two locking methods in
7531 a non blocking way<footnote>
7532 If it is not possible to establish both locks, the
7533 system shouldn't wait for the second lock to be
7534 established, but remove the first lock, wait a (random)
7535 time, and start over locking again.
7536 </footnote>. Using the functions <tt>maillock</tt> and
7537 <tt>mailunlock</tt> provided by the
7538 <tt>liblockfile*</tt><footnote>
7539 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7540 to use these functions.
7541 </footnote> packages is the recommended way to realize this.
7545 Mailboxes are generally mode 660
7546 <tt><var>user</var>.mail</tt> unless the system
7547 administrator has chosen otherwise. A MUA may remove a
7548 mailbox (unless it has nonstandard permissions) in which
7549 case the MTA or another MUA must recreate it if needed.
7550 Mailboxes must be writable by group mail.
7554 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7555 be setgid mail to do the locking mentioned above (and
7556 must obviously avoid accessing other users' mailboxes
7557 using this privilege).</p>
7560 <file>/etc/aliases</file> is the source file for the system mail
7561 aliases (e.g., postmaster, usenet, etc.), it is the one
7562 which the sysadmin and <prgn>postinst</prgn> scripts may
7563 edit. After <file>/etc/aliases</file> is edited the program or
7564 human editing it must call <prgn>newaliases</prgn>. All MTA
7565 packages must come with a <prgn>newaliases</prgn> program,
7566 even if it does nothing, but older MTA packages did not do
7567 this so programs should not fail if <prgn>newaliases</prgn>
7568 cannot be found. Note that because of this, all MTA
7569 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7570 <tt>Replaces: mail-transport-agent</tt> control file
7575 The convention of writing <tt>forward to
7576 <var>address</var></tt> in the mailbox itself is not
7577 supported. Use a <tt>.forward</tt> file instead.</p>
7580 The <prgn>rmail</prgn> program used by UUCP
7581 for incoming mail should be <file>/usr/sbin/rmail</file>.
7582 Likewise, <prgn>rsmtp</prgn>, for receiving
7583 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7587 If your package needs to know what hostname to use on (for
7588 example) outgoing news and mail messages which are generated
7589 locally, you should use the file <file>/etc/mailname</file>. It
7590 will contain the portion after the username and <tt>@</tt>
7591 (at) sign for email addresses of users on the machine
7592 (followed by a newline).
7596 Such package should check for the existence of this file
7597 when it is being configured. If it exists, it should be
7598 used without comment, although an MTA's configuration script
7599 may wish to prompt the user even if it finds that this file
7600 exists. If the file does not exist, the package should
7601 prompt the user for the value (preferably using
7602 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7603 as well as using it in the package's configuration. The
7604 prompt should make it clear that the name will not just be
7605 used by that package. For example, in this situation the
7606 <tt>inn</tt> package could say something like:
7607 <example compact="compact">
7608 Please enter the "mail name" of your system. This is the
7609 hostname portion of the address to be shown on outgoing
7610 news and mail messages. The default is
7611 <var>syshostname</var>, your system's host name. Mail
7612 name ["<var>syshostname</var>"]:
7614 where <var>syshostname</var> is the output of <tt>hostname
7620 <heading>News system configuration</heading>
7623 All the configuration files related to the NNTP (news)
7624 servers and clients should be located under
7625 <file>/etc/news</file>.</p>
7628 There are some configuration issues that apply to a number
7629 of news clients and server packages on the machine. These
7633 <tag><file>/etc/news/organization</file></tag>
7635 A string which should appear as the
7636 organization header for all messages posted
7637 by NNTP clients on the machine
7640 <tag><file>/etc/news/server</file></tag>
7642 Contains the FQDN of the upstream NNTP
7643 server, or localhost if the local machine is
7648 Other global files may be added as required for cross-package news
7655 <heading>Programs for the X Window System</heading>
7658 <heading>Providing X support and package priorities</heading>
7661 Programs that can be configured with support for the X
7662 Window System must be configured to do so and must declare
7663 any package dependencies necessary to satisfy their
7664 runtime requirements when using the X Window System. If
7665 such a package is of higher priority than the X packages
7666 on which it depends, it is required that either the
7667 X-specific components be split into a separate package, or
7668 that an alternative version of the package, which includes
7669 X support, be provided, or that the package's priority be
7675 <heading>Packages providing an X server</heading>
7678 Packages that provide an X server that, directly or
7679 indirectly, communicates with real input and display
7680 hardware should declare in their control data that they
7681 provide the virtual package <tt>xserver</tt>.<footnote>
7682 This implements current practice, and provides an
7683 actual policy for usage of the <tt>xserver</tt>
7684 virtual package which appears in the virtual packages
7685 list. In a nutshell, X servers that interface
7686 directly with the display and input hardware or via
7687 another subsystem (e.g., GGI) should provide
7688 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7689 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7695 <heading>Packages providing a terminal emulator</heading>
7698 Packages that provide a terminal emulator for the X Window
7699 System which meet the criteria listed below should declare
7700 in their control data that they provide the virtual
7701 package <tt>x-terminal-emulator</tt>. They should also
7702 register themselves as an alternative for
7703 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7708 To be an <tt>x-terminal-emulator</tt>, a program must:
7709 <list compact="compact">
7711 Be able to emulate a DEC VT100 terminal, or a
7712 compatible terminal.
7716 Support the command-line option <tt>-e
7717 <var>command</var></tt>, which creates a new
7718 terminal window<footnote>
7719 "New terminal window" does not necessarily mean
7720 a new top-level X window directly parented by
7721 the window manager; it could, if the terminal
7722 emulator application were so coded, be a new
7723 "view" in a multiple-document interface (MDI).
7725 and runs the specified <var>command</var>,
7726 interpreting the entirity of the rest of the command
7727 line as a command to pass straight to exec, in the
7728 manner that <tt>xterm</tt> does.
7732 Support the command-line option <tt>-T
7733 <var>title</var></tt>, which creates a new terminal
7734 window with the window title <var>title</var>.
7741 <heading>Packages providing a window manager</heading>
7744 Packages that provide a window manager should declare in
7745 their control data that they provide the virtual package
7746 <tt>x-window-manager</tt>. They should also register
7747 themselves as an alternative for
7748 <file>/usr/bin/x-window-manager</file>, with a priority
7749 calculated as follows:
7750 <list compact="compact">
7752 Start with a priority of 20.
7756 If the window manager supports the Debian menu
7757 system, add 20 points if this support is available
7758 in the package's default configuration (i.e., no
7759 configuration files belonging to the system or user
7760 have to be edited to activate the feature); if
7761 configuration files must be modified, add only 10
7767 If the window manager complies with <url
7768 id="http://www.freedesktop.org/Standards/wm-spec"
7769 name="The Window Manager Specification Project">,
7770 written by the <url id="http://www.freedesktop.org/"
7771 name="Free Desktop Group">, add 40 points.
7775 If the window manager permits the X session to be
7776 restarted using a <em>different</em> window manager
7777 (without killing the X server) in its default
7778 configuration, add 10 points; otherwise add none.
7785 <heading>Packages providing fonts</heading>
7788 Packages that provide fonts for the X Window
7790 For the purposes of Debian Policy, a "font for the X
7791 Window System" is one which is accessed via X protocol
7792 requests. Fonts for the Linux console, for PostScript
7793 renderers, or any other purpose, do not fit this
7794 definition. Any tool which makes such fonts available
7795 to the X Window System, however, must abide by this
7798 must do a number of things to ensure that they are both
7799 available without modification of the X or font server
7800 configuration, and that they do not corrupt files used by
7801 other font packages to register information about
7805 Fonts of any type supported by the X Window System
7806 must be in a separate binary package from any
7807 executables, libraries, or documentation (except
7808 that specific to the fonts shipped, such as their
7809 license information). If one or more of the fonts
7810 so packaged are necessary for proper operation of
7811 the package with which they are associated the font
7812 package may be Recommended; if the fonts merely
7813 provide an enhancement, a Suggests relationship may
7814 be used. Packages must not Depend on font
7816 This is because the X server may retrieve fonts
7817 from the local filesystem or over the network
7818 from an X font server; the Debian package system
7819 is empowered to deal only with the local
7825 BDF fonts must be converted to PCF fonts with the
7826 <prgn>bdftopcf</prgn> utility (available in the
7827 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7828 placed in a directory that corresponds to their
7830 <list compact="compact">
7832 100 dpi fonts must be placed in
7833 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7837 75 dpi fonts must be placed in
7838 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7842 Character-cell fonts, cursor fonts, and other
7843 low-resolution fonts must be placed in
7844 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7850 Speedo fonts must be placed in
7851 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7855 Type 1 fonts must be placed in
7856 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7857 metric files are available, they must be placed here
7862 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7863 other than those listed above must be neither
7864 created nor used. (The <file>PEX</file>, <file>CID</file>,
7865 and <file>cyrillic</file> directories are excepted for
7866 historical reasons, but installation of files into
7867 these directories remains discouraged.)
7871 Font packages may, instead of placing files directly
7872 in the X font directories listed above, provide
7873 symbolic links in that font directory pointing to
7874 the files' actual location in the filesystem. Such
7875 a location must comply with the FHS.
7879 Font packages should not contain both 75dpi and
7880 100dpi versions of a font. If both are available,
7881 they should be provided in separate binary packages
7882 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7883 the names of the packages containing the
7884 corresponding fonts.
7888 Fonts destined for the <file>misc</file> subdirectory
7889 should not be included in the same package as 75dpi
7890 or 100dpi fonts; instead, they should be provided in
7891 a separate package with <tt>-misc</tt> appended to
7896 Font packages must not provide the files
7897 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7898 <file>fonts.scale</file> in a font directory:
7901 <file>fonts.dir</file> files must not be provided at all.
7905 <file>fonts.alias</file> and <file>fonts.scale</file>
7906 files, if needed, should be provided in the
7908 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7909 where <var>fontdir</var> is the name of the
7911 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7912 package's corresponding fonts are stored
7913 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7914 <var>package</var> is the name of the package
7915 that provides these fonts, and
7916 <var>extension</var> is either <tt>scale</tt>
7917 or <tt>alias</tt>, whichever corresponds to
7924 Font packages must declare a dependency on
7925 <tt>xutils (>> 4.0.3)</tt> in their control
7930 Font packages that provide one or more
7931 <file>fonts.scale</file> files as described above must
7932 invoke <prgn>update-fonts-scale</prgn> on each
7933 directory into which they installed fonts
7934 <em>before</em> invoking
7935 <prgn>update-fonts-dir</prgn> on that directory.
7936 This invocation must occur in both the
7937 <prgn>postinst</prgn> (for all arguments) and
7938 <prgn>postrm</prgn> (for all arguments except
7939 <tt>upgrade</tt>) scripts.
7943 Font packages that provide one or more
7944 <file>fonts.alias</file> files as described above must
7945 invoke <prgn>update-fonts-alias</prgn> on each
7946 directory into which they installed fonts. This
7947 invocation must occur in both the
7948 <prgn>postinst</prgn> (for all arguments) and
7949 <prgn>postrm</prgn> (for all arguments except
7950 <tt>upgrade</tt>) scripts.
7954 Font packages must invoke
7955 <prgn>update-fonts-dir</prgn> on each directory into
7956 which they installed fonts. This invocation must
7957 occur in both the <prgn>postinst</prgn> (for all
7958 arguments) and <prgn>postrm</prgn> (for all
7959 arguments except <tt>upgrade</tt>) scripts.
7963 Font packages must not provide alias names for the
7964 fonts they include which collide with alias names
7965 already in use by fonts already packaged.
7969 Font packages must not provide fonts with the same
7970 XLFD registry name as another font already packaged.
7977 <heading>Application defaults files</heading>
7980 Application defaults files must be installed in the
7981 directory <file>/etc/X11/app-defaults/</file> (use of a
7982 localized subdirectory of <file>/etc/X11/</file> as described
7983 in the <em>X Toolkit Intrinsics - C Language
7984 Interface</em> manual is also permitted). They must be
7985 registered as <tt>conffile</tt>s or handled as
7986 configuration files. Packages must not provide the
7987 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7991 Customization of programs' X resources may also be
7992 supported with the provision of a file with the same name
7993 as that of the package placed in the
7994 <file>/etc/X11/Xresources/</file> directory, which must
7995 registered as a <tt>conffile</tt> or handled as a
7996 configuration file.<footnote>
7997 Note that this mechanism is not the same as using
7998 app-defaults; app-defaults are tied to the client
7999 binary on the local filesystem, whereas X resources
8000 are stored in the X server and affect all connecting
8003 <em>Important:</em> packages that install files into the
8004 <file>/etc/X11/Xresources/</file> directory must conflict with
8005 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
8006 it is possible for the installing package to destroy a
8007 previously-existing <file>/etc/X11/Xresources</file> file
8008 which had been customized by the system administrator.
8013 <heading>Installation directory issues</heading>
8016 Packages using the X Window System should not be
8017 configured to install files under the <file>/usr/X11R6/</file>
8018 directory unless they use <prgn>imake</prgn>. The
8019 <file>/usr/X11R6/</file> directory hierarchy should be
8020 regarded as deprecated for all packages except the X
8021 Window System itself, and those which use the
8022 <prgn>imake</prgn> program it provides, in which case the
8023 packages may transition out of the <file>/usr/X11R6/</file>
8024 directory at the maintainer's discretion.<footnote>
8025 <prgn>Imake</prgn>-using programs are exempt because,
8026 as long as they are written correctly, the pathnames
8027 they use to locate resources and install themselves
8028 are derived wholly from the X Window System
8029 configuration. Thus, in the event that the X Window
8030 System moves to <file>/usr/X11R7/</file>,
8031 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
8032 that is required for these programs is a recompile
8033 against the corresponding X Window System library
8034 development packages.
8039 Programs that use GNU <prgn>autoconf</prgn> and
8040 <prgn>automake</prgn> are usually easily configured at
8041 compile time to use <file>/usr/</file> instead of
8042 <file>/usr/X11R6/</file>, and this should be done whenever
8043 possible. Configuration files for window managers and
8044 display managers should be placed in a subdirectory of
8045 <file>/etc/X11/</file> corresponding to the package name due
8046 to these programs' tight integration with the mechanisms
8047 of the X Window System. Application-level programs should
8048 use the <file>/etc/</file> directory unless otherwise mandated
8053 The installation of files into subdirectories
8054 of <file>/usr/X11R6/include/X11/</file> and
8055 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8056 package maintainers should determine if subdirectories of
8057 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8058 instead. (The use of symbolic links from the
8059 <file>X11R6</file> directories to other FHS-compliant
8060 locations is encouraged if the program is not easily
8061 configured to look elsewhere for its files.)
8065 Packages must not provide or install files into the directories
8066 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8067 <file>/usr/lib/X11/</file>. Files within a package should,
8068 however, make reference to these directories, rather than
8069 their <tt>X11R6</tt>-named counterparts
8070 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8071 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8072 referred to have not been moved to other FHS-compliant
8078 <heading>The OSF/Motif and OpenMotif libraries</heading>
8081 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8082 OpenMotif libraries</em><footnote>
8083 OSF/Motif and OpenMotif are collectively referred to as
8084 "Motif" in this policy document.
8086 should be compiled against and tested with LessTif (a free
8087 re-implementation of Motif) instead. If the maintainer
8088 judges that the program or programs do not work
8089 sufficiently well with LessTif to be distributed and
8090 supported, but do so when compiled against Motif, then two
8091 versions of the package should be created; one linked
8092 statically against Motif and with <tt>-smotif</tt>
8093 appended to the package name, and one linked dynamically
8094 against Motif and with <tt>-dmotif</tt> appended to the
8099 Both Motif-linked versions are dependent
8100 upon non-DFSG-compliant software and thus cannot be
8101 uploaded to the <em>main</em> distribution; if the
8102 software is itself DFSG-compliant it may be uploaded to
8103 the <em>contrib</em> distribution. While known existing
8104 versions of Motif permit unlimited redistribution of
8105 binaries linked against the library (whether statically or
8106 dynamically), it is the package maintainer's
8107 responsibility to determine whether this is permitted by
8108 the license of the copy of Motif in their possession.
8114 <heading>Perl programs and modules</heading>
8117 Perl programs and modules should follow the current Perl policy.
8121 The Perl policy can be found in the <tt>perl-policy</tt>
8122 files in the <tt>debian-policy</tt> package.
8123 It is also available from the Debian web mirrors at
8124 <tt><url name="/doc/packaging-manuals/perl-policy/"
8125 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8130 <heading>Emacs lisp programs</heading>
8133 Please refer to the "Debian Emacs Policy" for details of how to
8134 package emacs lisp programs.
8138 The Emacs policy is available in
8139 <file>debian-emacs-policy.gz</file> of the
8140 <package>emacsen-common</package> package.
8141 It is also available from the Debian web mirrors at
8142 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8143 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8148 <heading>Games</heading>
8151 The permissions on <file>/var/games</file> are mode 755, owner
8152 <tt>root</tt> and group <tt>root</tt>.
8156 Each game decides on its own security policy.</p>
8159 Games which require protected, privileged access to
8160 high-score files, savegames, etc., may be made
8161 set-<em>group</em>-id (mode 2755) and owned by
8162 <tt>root.games</tt>, and use files and directories with
8163 appropriate permissions (770 <tt>root.games</tt>, for
8164 example). They must not be made
8165 set-<em>user</em>-id, as this causes security problems. (If
8166 an attacker can subvert any set-user-id game they can
8167 overwrite the executable of any other, causing other players
8168 of these games to run a Trojan horse program. With a
8169 set-group-id game the attacker only gets access to less
8170 important game data, and if they can get at the other
8171 players' accounts at all it will take considerably more
8175 Some packages, for example some fortune cookie programs, are
8176 configured by the upstream authors to install with their
8177 data files or other static information made unreadable so
8178 that they can only be accessed through set-id programs
8179 provided. You should not do this in a Debian package: anyone can
8180 download the <file>.deb</file> file and read the data from it,
8181 so there is no point making the files unreadable. Not
8182 making the files unreadable also means that you don't have
8183 to make so many programs set-id, which reduces the risk of a
8187 As described in the FHS, binaries of games should be
8188 installed in the directory <file>/usr/games</file>. This also
8189 applies to games that use the X Window System. Manual pages
8190 for games (X and non-X games) should be installed in
8191 <file>/usr/share/man/man6</file>.</p>
8197 <heading>Documentation</heading>
8200 <heading>Manual pages</heading>
8203 You should install manual pages in <prgn>nroff</prgn> source
8204 form, in appropriate places under <file>/usr/share/man</file>.
8205 You should only use sections 1 to 9 (see the FHS for more
8206 details). You must not install a preformatted "cat page".
8210 Each program, utility, and function should have an
8211 associated manual page included in the same package. It is
8212 suggested that all configuration files also have a manual
8213 page included as well. Manual pages for protocols and other
8214 auxiliary things are optional.
8218 If no manual page is available, this is considered as a bug
8219 and should be reported to the Debian Bug Tracking System (the
8220 maintainer of the package is allowed to write this bug report
8221 themselves, if they so desire). Do not close the bug report
8222 until a proper man page is available.<footnote>
8223 It is not very hard to write a man page. See the
8224 <url id="http://www.schweikhardt.net/man_page_howto.html"
8225 name="Man-Page-HOWTO">,
8226 <manref name="man" section="7">, the examples
8227 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8228 the helper programs <prgn>help2man</prgn>, or the
8229 directory <file>/usr/share/doc/man-db/examples</file>.
8234 You may forward a complaint about a missing man page to the
8235 upstream authors, and mark the bug as forwarded in the
8236 Debian bug tracking system. Even though the GNU Project do
8237 not in general consider the lack of a man page to be a bug,
8238 we do; if they tell you that they don't consider it a bug
8239 you should leave the bug in our bug tracking system open
8244 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8248 If one man page needs to be accessible via several names it
8249 is better to use a symbolic link than the <file>.so</file>
8250 feature, but there is no need to fiddle with the relevant
8251 parts of the upstream source to change from <file>.so</file> to
8252 symlinks: don't do it unless it's easy. You should not
8253 create hard links in the manual page directories, nor put
8254 absolute filenames in <file>.so</file> directives. The filename
8255 in a <file>.so</file> in a man page should be relative to the
8256 base of the man page tree (usually
8257 <file>/usr/share/man</file>). If you do not create any links
8258 (whether symlinks, hard links, or <tt>.so</tt> directives)
8259 in the filesystem to the alternate names of the man page,
8260 then you should not rely on <prgn>man</prgn> finding your
8261 man page under those names based solely on the information in
8262 the man page's header.<footnote>
8263 Supporting this in <prgn>man</prgn> often requires
8264 unreasonable processing time to find a manual page or to
8265 report that none exists, and moves knowledge into man's
8266 database that would be better left in the filesystem.
8267 This support is therefore deprecated and will cease to
8268 be present in the future.
8274 <heading>Info documents</heading>
8277 Info documents should be installed in <file>/usr/share/info</file>.
8278 They should be compressed with <tt>gzip -9</tt>.
8282 Your package should call <prgn>install-info</prgn> to update
8283 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8284 script when called with a <tt>configure</tt> argument, for
8286 <example compact="compact">
8287 install-info --quiet --section Development Development \
8288 /usr/share/info/foobar.info
8292 It is a good idea to specify a section for the location of
8293 your program; this is done with the <tt>--section</tt>
8294 switch. To determine which section to use, you should look
8295 at <file>/usr/share/info/dir</file> on your system and choose the most
8296 relevant (or create a new section if none of the current
8297 sections are relevant). Note that the <tt>--section</tt>
8298 flag takes two arguments; the first is a regular expression
8299 to match (case-insensitively) against an existing section,
8300 the second is used when creating a new one.</p>
8303 You should remove the entries in the <prgn>prerm</prgn>
8304 script when called with a <tt>remove</tt> argument:
8305 <example compact="compact">
8306 install-info --quiet --remove /usr/share/info/foobar.info
8310 If <prgn>install-info</prgn> cannot find a description entry
8311 in the Info file you must supply one. See <manref
8312 name="install-info" section="8"> for details.</p>
8316 <heading>Additional documentation</heading>
8319 Any additional documentation that comes with the package may
8320 be installed at the discretion of the package maintainer.
8321 Text documentation should be installed in the directory
8322 <file>/usr/share/doc/<var>package</var></file>, where
8323 <var>package</var> is the name of the package, and
8324 compressed with <tt>gzip -9</tt> unless it is small.
8328 If a package comes with large amounts of documentation which
8329 many users of the package will not require you should create
8330 a separate binary package to contain it, so that it does not
8331 take up disk space on the machines of users who do not need
8332 or want it installed.</p>
8335 It is often a good idea to put text information files
8336 (<file>README</file>s, changelogs, and so forth) that come with
8337 the source package in <file>/usr/share/doc/<var>package</var></file>
8338 in the binary package. However, you don't need to install
8339 the instructions for building and installing the package, of
8343 Packages must not require the existence of any files in
8344 <file>/usr/share/doc/</file> in order to function
8346 The system administrator should be able to
8347 delete files in <file>/usr/share/doc/</file> without causing
8348 any programs to break.
8350 Any files that are referenced by programs but are also
8351 useful as standalone documentation should be installed under
8352 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8353 <file>/usr/share/doc/<var>package</var></file>.
8357 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8358 link to another directory in <file>/usr/share/doc</file> only if
8359 the two packages both come from the same source and the
8360 first package Depends on the second.<footnote>
8362 Please note that this does not override the section on
8363 changelog files below, so the file
8364 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8365 must refer to the changelog for the current version of
8366 <var>package</var> in question. In practice, this means
8367 that the sources of the target and the destnation of the
8368 symlink must be the same (same source package and
8375 Former Debian releases placed all additional documentation
8376 in <file>/usr/doc/<var>package</var></file>. This has been
8377 changed to <file>/usr/share/doc/<var>package</var></file>,
8378 and packages must not put documentation in the directory
8379 <file>/usr/doc/<var>package</var></file>. <footnote>
8380 At this phase of the transition, we no longer require a
8381 symbolic link in <file>/usr/doc/</file>. At a later point,
8382 policy shall change to make the symbolic links a bug.
8388 <heading>Preferred documentation formats</heading>
8391 The unification of Debian documentation is being carried out
8395 If your package comes with extensive documentation in a
8396 markup format that can be converted to various other formats
8397 you should if possible ship HTML versions in a binary
8398 package, in the directory
8399 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8400 its subdirectories.<footnote>
8401 The rationale: The important thing here is that HTML
8402 docs should be available in <em>some</em> package, not
8403 necessarily in the main binary package.
8408 Other formats such as PostScript may be provided at the
8409 package maintainer's discretion.
8413 <sect id="copyrightfile">
8414 <heading>Copyright information</heading>
8417 Every package must be accompanied by a verbatim copy of its
8418 copyright and distribution license in the file
8419 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8420 file must neither be compressed nor be a symbolic link.
8424 In addition, the copyright file must say where the upstream
8425 sources (if any) were obtained. It should name the original
8426 authors of the package and the Debian maintainer(s) who were
8427 involved with its creation.</p>
8430 A copy of the file which will be installed in
8431 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8432 be in <file>debian/copyright</file> in the source package.
8436 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8437 link to another directory in <file>/usr/share/doc</file> only if
8438 the two packages both come from the same source and the
8439 first package Depends on the second. These rules are
8440 important because copyrights must be extractable by
8445 Packages distributed under the UCB BSD license, the Artistic
8446 license, the GNU GPL, and the GNU LGPL should refer to the
8447 files <file>/usr/share/common-licenses/BSD</file>,
8448 <file>/usr/share/common-licenses/Artistic</file>,
8449 <file>/usr/share/common-licenses/GPL</file>, and
8450 <file>/usr/share/common-licenses/LGPL</file> respectively,
8451 rather than quoting them in the copyright file.
8455 You should not use the copyright file as a general <file>README</file>
8456 file. If your package has such a file it should be
8457 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8458 <file>README.Debian</file> or some other appropriate place.</p>
8462 <heading>Examples</heading>
8465 Any examples (configurations, source files, whatever),
8466 should be installed in a directory
8467 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8468 files should not be referenced by any program: they're there
8469 for the benefit of the system administrator and users as
8470 documentation only. Architecture-specific example files
8471 should be installed in a directory
8472 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8474 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8475 latter directory itself may be a symbolic link to the
8480 If the purpose of a package is to provide examples, then the
8481 example files may be installed into
8482 <file>/usr/share/doc/<var>package</var></file>.
8486 <sect id="changelogs">
8487 <heading>Changelog files</heading>
8490 Packages that are not Debian-native must contain a
8491 compressed copy of the <file>debian/changelog</file> file from
8492 the Debian source tree in
8493 <file>/usr/share/doc/<var>package</var></file> with the name
8494 <file>changelog.Debian.gz</file>.
8498 If an upstream changelog is available, it should be accessible as
8499 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8500 plain text. If the upstream changelog is distributed in
8501 HTML, it should be made available in that form as
8502 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8503 and a plain text <file>changelog.gz</file> should be generated
8504 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8505 the upstream changelog files do not already conform to this
8506 naming convention, then this may be achieved either by
8507 renaming the files, or by adding a symbolic link, at the
8508 maintainer's discretion.<footnote>
8509 Rationale: People should not have to look in places for
8510 upstream changelogs merely because they are given
8511 different names or are distributed in HTML format.
8516 All of these files should be installed compressed using
8517 <tt>gzip -9</tt>, as they will become large with time even
8518 if they start out small.
8522 If the package has only one changelog which is used both as
8523 the Debian changelog and the upstream one because there is
8524 no separate upstream maintainer then that changelog should
8525 usually be installed as
8526 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8527 there is a separate upstream maintainer, but no upstream
8528 changelog, then the Debian changelog should still be called
8529 <file>changelog.Debian.gz</file>.
8533 For details about the format and contents of the Debian
8534 changelog file, please see <ref id="dpkgchangelog">.
8539 <appendix id="pkg-scope">
8540 <heading>Introduction and scope of these appendices</heading>
8543 These appendices are taken essentially verbatim from the
8544 now-deprecated Packaging Manual, version 3.2.1.0. They are
8545 the chapters which are likely to be of use to package
8546 maintainers and which have not already been included in the
8547 policy document itself. Most of these sections are very likely
8548 not relevant to policy; they should be treated as
8549 documentation for the packaging system. Please note that these
8550 appendices are included for convenience, and for historical
8551 reasons: they used to be part of policy package, and they have
8552 not yet been incorporated into dpkg documentation. However,
8553 they still have value, and hence they are presented here.
8557 They have not yet been checked to ensure that they are
8558 compatible with the contents of policy, and if there are any
8559 contradictions, the version in the main policy document takes
8560 precedence. The remaining chapters of the old Packaging
8561 Manual have also not been read in detail to ensure that there
8562 are not parts which have been left out. Both of these will be
8567 Certain parts of the Packaging manual were integrated into the
8568 Policy Manual proper, and removed from the appendices. Links
8569 have been placed from the old locations to the new ones.
8573 <prgn>dpkg</prgn> is a suite of programs for creating binary
8574 package files and installing and removing them on Unix
8576 <prgn>dpkg</prgn> is targetted primarily at Debian
8577 GNU/Linux, but may work on or be ported to other
8583 The binary packages are designed for the management of
8584 installed executable programs (usually compiled binaries) and
8585 their associated data, though source code examples and
8586 documentation are provided as part of some packages.</p>
8589 This manual describes the technical aspects of creating Debian
8590 binary packages (<file>.deb</file> files). It documents the
8591 behaviour of the package management programs
8592 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8593 they interact with packages.</p>
8596 It also documents the interaction between
8597 <prgn>dselect</prgn>'s core and the access method scripts it
8598 uses to actually install the selected packages, and describes
8599 how to create a new access method.</p>
8602 This manual does not go into detail about the options and
8603 usage of the package building and installation tools. It
8604 should therefore be read in conjuction with those programs'
8609 The utility programs which are provided with <prgn>dpkg</prgn>
8610 for managing various system configuration and similar issues,
8611 such as <prgn>update-rc.d</prgn> and
8612 <prgn>install-info</prgn>, are not described in detail here -
8613 please see their man pages.
8617 It is assumed that the reader is reasonably familiar with the
8618 <prgn>dpkg</prgn> System Administrators' manual.
8619 Unfortunately this manual does not yet exist.
8623 The Debian version of the FSF's GNU hello program is provided
8624 as an example for people wishing to create Debian
8625 packages. The Debian <prgn>debmake</prgn> package is
8626 recommended as a very helpful tool in creating and maintaining
8627 Debian packages. However, while the tools and examples are
8628 helpful, they do not replace the need to read and follow the
8629 Policy and Programmer's Manual.</p>
8632 <appendix id="pkg-binarypkg">
8633 <heading>Binary packages (from old Packaging Manual)</heading>
8636 The binary package has two main sections. The first part
8637 consists of various control information files and scripts used
8638 by <prgn>dpkg</prgn> when installing and removing. See <ref
8639 id="pkg-controlarea">.
8643 The second part is an archive containing the files and
8644 directories to be installed.
8648 In the future binary packages may also contain other
8649 components, such as checksums and digital signatures. The
8650 format for the archive is described in full in the
8651 <file>deb(5)</file> man page.
8655 <sect id="pkg-bincreating"><heading>Creating package files -
8656 <prgn>dpkg-deb</prgn>
8660 All manipulation of binary package files is done by
8661 <prgn>dpkg-deb</prgn>; it's the only program that has
8662 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8663 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8664 will spot that the options requested are appropriate to
8665 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8670 In order to create a binary package you must make a
8671 directory tree which contains all the files and directories
8672 you want to have in the filesystem data part of the package.
8673 In Debian-format source packages this directory is usually
8674 <file>debian/tmp</file>, relative to the top of the package's
8679 They should have the locations (relative to the root of the
8680 directory tree you're constructing) ownerships and
8681 permissions which you want them to have on the system when
8686 With current versions of <prgn>dpkg</prgn> the uid/username
8687 and gid/groupname mappings for the users and groups being
8688 used should be the same on the system where the package is
8689 built and the one where it is installed.
8693 You need to add one special directory to the root of the
8694 miniature filesystem tree you're creating:
8695 <prgn>DEBIAN</prgn>. It should contain the control
8696 information files, notably the binary package control file
8697 (see <ref id="pkg-controlfile">).
8701 The <prgn>DEBIAN</prgn> directory will not appear in the
8702 filesystem archive of the package, and so won't be installed
8703 by <prgn>dpkg</prgn> when the package is installed.
8707 When you've prepared the package, you should invoke:
8709 dpkg --build <var>directory</var>
8714 This will build the package in
8715 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8716 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8717 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8722 See the man page <manref name="dpkg-deb" section="8"> for details of how
8723 to examine the contents of this newly-created file. You may find the
8724 output of following commands enlightening:
8726 dpkg-deb --info <var>filename</var>.deb
8727 dpkg-deb --contents <var>filename</var>.deb
8728 dpkg --contents <var>filename</var>.deb
8730 To view the copyright file for a package you could use this command:
8732 dpkg --fsys-tarfile <var>filename</var>.deb | tar xO ./usr/share/doc/\*/copyright | pager
8737 <sect id="pkg-controlarea">
8738 <heading>Package control information files</heading>
8741 The control information portion of a binary package is a
8742 collection of files with names known to <prgn>dpkg</prgn>.
8743 It will treat the contents of these files specially - some
8744 of them contain information used by <prgn>dpkg</prgn> when
8745 installing or removing the package; others are scripts which
8746 the package maintainer wants <prgn>dpkg</prgn> to run.
8750 It is possible to put other files in the package control
8751 area, but this is not generally a good idea (though they
8752 will largely be ignored).
8756 Here is a brief list of the control info files supported by
8757 <prgn>dpkg</prgn> and a summary of what they're used for.
8762 <tag><tt>control</tt>
8765 This is the key description file used by
8766 <prgn>dpkg</prgn>. It specifies the package's name
8767 and version, gives its description for the user,
8768 states its relationships with other packages, and so
8769 forth. See <ref id="sourcecontrolfiles"> and
8770 <ref id="binarycontrolfiles">.
8774 It is usually generated automatically from information
8775 in the source package by the
8776 <prgn>dpkg-gencontrol</prgn> program, and with
8777 assistance from <prgn>dpkg-shlibdeps</prgn>.
8778 See <ref id="pkg-sourcetools">.
8782 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8787 These are exectuable files (usually scripts) which
8788 <prgn>dpkg</prgn> runs during installation, upgrade
8789 and removal of packages. They allow the package to
8790 deal with matters which are particular to that package
8791 or require more complicated processing than that
8792 provided by <prgn>dpkg</prgn>. Details of when and
8793 how they are called are in <ref id="maintainerscripts">.
8797 It is very important to make these scripts idempotent.
8798 See <ref id="idempotency">.
8802 The maintainer scripts are guaranteed to run with a
8803 controlling terminal and can interact with the user.
8804 See <ref id="controllingterminal">.
8808 <tag><tt>conffiles</tt>
8811 This file contains a list of configuration files which
8812 are to be handled automatically by <prgn>dpkg</prgn>
8813 (see <ref id="pkg-conffiles">). Note that not necessarily
8814 every configuration file should be listed here.
8817 <tag><tt>shlibs</tt>
8820 This file contains a list of the shared libraries
8821 supplied by the package, with dependency details for
8822 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8823 when it determines what dependencies are required in a
8824 package control file. The <tt>shlibs</tt> file format
8825 is described on <ref id="shlibs">.
8830 <sect id="pkg-controlfile">
8831 <heading>The main control information file: <tt>control</tt></heading>
8834 The most important control information file used by
8835 <prgn>dpkg</prgn> when it installs a package is
8836 <tt>control</tt>. It contains all the package's "vital
8841 The binary package control files of packages built from
8842 Debian sources are made by a special tool,
8843 <prgn>dpkg-gencontrol</prgn>, which reads
8844 <file>debian/control</file> and <file>debian/changelog</file> to
8845 find the information it needs. See <ref id="pkg-sourcepkg"> for
8850 The fields in binary package control files are listed in
8851 <ref id="binarycontrolfiles">.
8855 A description of the syntax of control files and the purpose
8856 of the fields is available in <ref id="controlfields">.
8861 <heading>Time Stamps</heading>
8864 See <ref id="timestamps">.
8869 <appendix id="pkg-sourcepkg">
8870 <heading>Source packages (from old Packaging Manual) </heading>
8873 The Debian binary packages in the distribution are generated
8874 from Debian sources, which are in a special format to assist
8875 the easy and automatic building of binaries.
8878 <sect id="pkg-sourcetools">
8879 <heading>Tools for processing source packages</heading>
8882 Various tools are provided for manipulating source packages;
8883 they pack and unpack sources and help build of binary
8884 packages and help manage the distribution of new versions.
8888 They are introduced and typical uses described here; see
8889 <manref name="dpkg-source" section="1"> for full
8890 documentation about their arguments and operation.
8894 For examples of how to construct a Debian source package,
8895 and how to use those utilities that are used by Debian
8896 source packages, please see the <prgn>hello</prgn> example
8900 <sect1 id="pkg-dpkg-source">
8902 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8907 This program is frequently used by hand, and is also
8908 called from package-independent automated building scripts
8909 such as <prgn>dpkg-buildpackage</prgn>.
8913 To unpack a package it is typically invoked with
8915 dpkg-source -x <var>.../path/to/filename</var>.dsc
8920 with the <file><var>filename</var>.tar.gz</file> and
8921 <file><var>filename</var>.diff.gz</file> (if applicable) in
8922 the same directory. It unpacks into
8923 <file><var>package</var>-<var>version</var></file>, and if
8925 <file><var>package</var>-<var>version</var>.orig</file>, in
8926 the current directory.
8930 To create a packed source archive it is typically invoked:
8932 dpkg-source -b <var>package</var>-<var>version</var>
8937 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8938 <file>.diff.gz</file> (if appropriate) in the current
8939 directory. <prgn>dpkg-source</prgn> does not clean the
8940 source tree first - this must be done separately if it is
8945 See also <ref id="pkg-sourcearchives">.</p>
8949 <sect1 id="pkg-dpkg-buildpackage">
8951 <prgn>dpkg-buildpackage</prgn> - overall package-building
8956 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8957 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8958 targets <tt>clean</tt>, <tt>build</tt> and
8959 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8960 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8961 source and binary package upload.
8965 It is usually invoked by hand from the top level of the
8966 built or unbuilt source directory. It may be invoked with
8967 no arguments; useful arguments include:
8968 <taglist compact="compact">
8969 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8972 Do not sign the <tt>.changes</tt> file or the
8973 source package <tt>.dsc</tt> file, respectively.</p>
8975 <tag><tt>-p<var>sign-command</var></tt></tag>
8978 Invoke <var>sign-command</var> instead of finding
8979 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8980 <var>sign-command</var> must behave just like
8981 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
8983 <tag><tt>-r<var>root-command</var></tt></tag>
8986 When root privilege is required, invoke the command
8987 <var>root-command</var>. <var>root-command</var>
8988 should invoke its first argument as a command, from
8989 the <prgn>PATH</prgn> if necessary, and pass its
8990 second and subsequent arguments to the command it
8991 calls. If no <var>root-command</var> is supplied
8992 then <var>dpkg-buildpackage</var> will take no
8993 special action to gain root privilege, so that for
8994 most packages it will have to be invoked as root to
8997 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9000 Two types of binary-only build and upload - see
9001 <manref name="dpkg-source" section="1">.
9008 <sect1 id="pkg-dpkg-gencontrol">
9010 <prgn>dpkg-gencontrol</prgn> - generates binary package
9015 This program is usually called from <file>debian/rules</file>
9016 (see <ref id="pkg-sourcetree">) in the top level of the source
9021 This is usually done just before the files and directories in the
9022 temporary directory tree where the package is being built have their
9023 permissions and ownerships set and the package is constructed using
9024 <prgn>dpkg-deb/</prgn>
9026 This is so that the control file which is produced has
9027 the right permissions
9032 <prgn>dpkg-gencontrol</prgn> must be called after all the
9033 files which are to go into the package have been placed in
9034 the temporary build directory, so that its calculation of
9035 the installed size of a package is correct.
9039 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9040 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9041 variable substitutions created by
9042 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9047 For a package which generates only one binary package, and
9048 which builds it in <file>debian/tmp</file> relative to the top
9049 of the source package, it is usually sufficient to call
9050 <prgn>dpkg-gencontrol</prgn>.
9054 Sources which build several binaries will typically need
9057 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9058 </example> The <tt>-P</tt> tells
9059 <prgn>dpkg-gencontrol</prgn> that the package is being
9060 built in a non-default directory, and the <tt>-p</tt>
9061 tells it which package's control file should be generated.
9065 <prgn>dpkg-gencontrol</prgn> also adds information to the
9066 list of files in <file>debian/files</file>, for the benefit of
9067 (for example) a future invocation of
9068 <prgn>dpkg-genchanges</prgn>.</p>
9071 <sect1 id="pkg-dpkg-shlibdeps">
9073 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9078 This program is usually called from <file>debian/rules</file>
9079 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9080 id="pkg-sourcetree">), in the top level of the source tree.
9084 Its arguments are executables.
9087 In a forthcoming dpkg version,
9088 <prgn>dpkg-shlibdeps</prgn> would be required to be
9089 called on shared libraries as well.
9092 They may be specified either in the locations in the
9093 source tree where they are created or in the locations
9094 in the temporary build tree where they are installed
9095 prior to binary package creation.
9097 </footnote> for which shared library dependencies should
9098 be included in the binary package's control file.
9102 If some of the found shared libraries should only
9103 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9104 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9105 by using the <tt>-d<var>dependency-field</var></tt> option
9106 before those executable(s). (Each <tt>-d</tt> option
9107 takes effect until the next <tt>-d</tt>.)
9111 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9112 output control file to be modified. Instead by default it
9113 adds to the <file>debian/substvars</file> file variable
9114 settings like <tt>shlibs:Depends</tt>. These variable
9115 settings must be referenced in dependency fields in the
9116 appropriate per-binary-package sections of the source
9121 For example, a package that generates an essential part
9122 which requires dependencies, and optional parts that
9123 which only require a recommendation, would separate those
9124 two sets of dependencies into two different fields.<footnote>
9125 At the time of writing, an example for this was the
9126 <package/xmms/ package, with Depends used for the xmms
9127 executable, Recommends for the plug-ins and Suggests for
9128 even more optional features provided by unzip.
9130 It can say in its <file>debian/rules</file>:
9132 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9133 -dRecommends <var>optionalpart anotheroptionalpart</var>
9135 and then in its main control file <file>debian/control</file>:
9138 Depends: ${shlibs:Pre-Depends}
9139 Recommends: ${shlibs:Recommends}
9145 Sources which produce several binary packages with
9146 different shared library dependency requirements can use
9147 the <tt>-p<var>varnameprefix</var></tt> option to override
9148 the default <tt>shlibs:</tt> prefix (one invocation of
9149 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9150 They can thus produce several sets of dependency
9151 variables, each of the form
9152 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9153 which can be referred to in the appropriate parts of the
9154 binary package control files.
9159 <sect1 id="pkg-dpkg-distaddfile">
9161 <prgn>dpkg-distaddfile</prgn> - adds a file to
9162 <file>debian/files</file>
9166 Some packages' uploads need to include files other than
9167 the source and binary package files.
9171 <prgn>dpkg-distaddfile</prgn> adds a file to the
9172 <file>debian/files</file> file so that it will be included in
9173 the <file>.changes</file> file when
9174 <prgn>dpkg-genchanges</prgn> is run.
9178 It is usually invoked from the <tt>binary</tt> target of
9179 <file>debian/rules</file>:
9181 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9183 The <var>filename</var> is relative to the directory where
9184 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9185 is usually the directory above the top level of the source
9186 tree. The <file>debian/rules</file> target should put the
9187 file there just before or just after calling
9188 <prgn>dpkg-distaddfile</prgn>.
9192 The <var>section</var> and <var>priority</var> are passed
9193 unchanged into the resulting <file>.changes</file> file.
9198 <sect1 id="pkg-dpkg-genchanges">
9200 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9205 This program is usually called by package-independent
9206 automatic building scripts such as
9207 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9212 It is usually called in the top level of a built source
9213 tree, and when invoked with no arguments will print out a
9214 straightforward <file>.changes</file> file based on the
9215 information in the source package's changelog and control
9216 file and the binary and source packages which should have
9222 <sect1 id="pkg-dpkg-parsechangelog">
9224 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9225 representation of a changelog
9229 This program is used internally by
9230 <prgn>dpkg-source</prgn> et al. It may also occasionally
9231 be useful in <file>debian/rules</file> and elsewhere. It
9232 parses a changelog, <file>debian/changelog</file> by default,
9233 and prints a control-file format representation of the
9234 information in it to standard output.
9238 <sect1 id="pkg-dpkg-architecture">
9240 <prgn>dpkg-architecture</prgn> - information about the build and
9245 This program can be used manually, but is also invoked by
9246 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9247 to set environment or make variables which specify the build and
9248 host architecture for the package building process.
9253 <sect id="pkg-sourcetree">
9254 <heading>The Debianised source tree</heading>
9257 The source archive scheme described later is intended to
9258 allow a Debianised source tree with some associated control
9259 information to be reproduced and transported easily. The
9260 Debianised source tree is a version of the original program
9261 with certain files added for the benefit of the
9262 Debianisation process, and with any other changes required
9263 made to the rest of the source code and installation
9268 The extra files created for Debian are in the subdirectory
9269 <file>debian</file> of the top level of the Debianised source
9270 tree. They are described below.
9273 <sect1 id="pkg-debianrules">
9274 <heading><file>debian/rules</file> - the main building script</heading>
9277 See <ref id="debianrules">.
9282 <sect1 id="pkg-dpkgchangelog">
9283 <heading><file>debian/changelog</file></heading>
9286 See <ref id="dpkgchangelog">.
9290 It is recommended that the entire changelog be encoded in the
9291 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9293 <url id="http://www.unicode.org/"
9294 name="Unicode">.<footnote>
9296 Support for Unicode, and specifically UTF-8, is
9297 steadily increasing among popular applications in
9298 Debian. For example, in unstable, GNOME 2 has
9299 excellent support (almost level 2) in almost all its
9300 applications; the big remaining one is gnome-terminal,
9301 of which one requires development versions in order to
9302 support UTF-8 (available in Debian experimental now if
9303 you want to play). I think that by the time sarge is
9304 released, UTF-8 support will start to hit critical
9307 I think it is fairly obvious that we need to
9308 eventually transition to UTF-8 for our package
9309 infrastructure; it is really the only sane charset in
9310 an international environment. Now, we can't switch to
9311 using UTF-8 for package control fields and the like
9312 until dpkg has better support, but one thing we can
9313 start doing today is requesting that Debian changelogs
9314 are UTF-8 encoded. At some point in time, we can start
9315 requiring them to do so.
9318 Checking for non-UTF8 characters in a changelog is
9319 trivial. Dump the file through
9320 <example>iconv -f utf-8 -t ucs-4</example>
9321 discard the output, and check the return
9322 value. If there are any characters in the stream
9323 which are invalid UTF-8 sequences, iconv will exit
9324 with an error code; and this will be the case for the
9325 vast majority of other character sets.
9330 <sect2><heading>Defining alternative changelog formats
9334 It is possible to use a different format to the standard
9335 one, by providing a parser for the format you wish to
9340 In order to have <tt>dpkg-parsechangelog</tt> run your
9341 parser, you must include a line within the last 40 lines
9342 of your file matching the Perl regular expression:
9343 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9344 parentheses should be the name of the format. For
9345 example, you might say:
9347 @@@ changelog-format: joebloggs @@@
9349 Changelog format names are non-empty strings of alphanumerics.
9353 If such a line exists then <tt>dpkg-parsechangelog</tt>
9354 will look for the parser as
9355 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9357 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9358 it is an error for it not to find it, or for it not to
9359 be an executable program. The default changelog format
9360 is <tt>dpkg</tt>, and a parser for it is provided with
9361 the <tt>dpkg</tt> package.
9365 The parser will be invoked with the changelog open on
9366 standard input at the start of the file. It should read
9367 the file (it may seek if it wishes) to determine the
9368 information required and return the parsed information
9369 to standard output in the form of a series of control
9370 fields in the standard format. By default it should
9371 return information about only the most recent version in
9372 the changelog; it should accept a
9373 <tt>-v<var>version</var></tt> option to return changes
9374 information from all versions present <em>strictly
9375 after</em> <var>version</var>, and it should then be an
9376 error for <var>version</var> not to be present in the
9382 <list compact="compact">
9383 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9384 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9385 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9386 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9387 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9388 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9389 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9394 If several versions are being returned (due to the use
9395 of <tt>-v</tt>), the urgency value should be of the
9396 highest urgency code listed at the start of any of the
9397 versions requested followed by the concatenated
9398 (space-separated) comments from all the versions
9399 requested; the maintainer, version, distribution and
9400 date should always be from the most recent version.
9404 For the format of the <tt>Changes</tt> field see
9405 <ref id="f-Changes">.
9409 If the changelog format which is being parsed always or
9410 almost always leaves a blank line between individual
9411 change notes these blank lines should be stripped out,
9412 so as to make the resulting output compact.
9416 If the changelog format does not contain date or package
9417 name information this information should be omitted from
9418 the output. The parser should not attempt to synthesise
9419 it or find it from other sources.
9423 If the changelog does not have the expected format the
9424 parser should exit with a nonzero exit status, rather
9425 than trying to muddle through and possibly generating
9430 A changelog parser may not interact with the user at
9436 <sect1 id="pkg-srcsubstvars">
9437 <heading><file>debian/substvars</file> and variable substitutions</heading>
9440 See <ref id="substvars">.
9446 <heading><file>debian/files</file></heading>
9449 See <ref id="debianfiles">.
9453 <sect1><heading><file>debian/tmp</file>
9457 This is the canonical temporary location for the
9458 construction of binary packages by the <tt>binary</tt>
9459 target. The directory <file>tmp</file> serves as the root of
9460 the filesystem tree as it is being constructed (for
9461 example, by using the package's upstream makefiles install
9462 targets and redirecting the output there), and it also
9463 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9464 id="pkg-bincreating">.
9468 If several binary packages are generated from the same
9469 source tree it is usual to use several
9470 <file>debian/tmp<var>something</var></file> directories, for
9471 example <file>tmp-a</file> or <file>tmp-doc</file>.
9475 Whatever <file>tmp</file> directories are created and used by
9476 <tt>binary</tt> must of course be removed by the
9477 <tt>clean</tt> target.</p></sect1>
9481 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9485 As it exists on the FTP site, a Debian source package
9486 consists of three related files. You must have the right
9487 versions of all three to be able to use them.
9492 <tag>Debian source control file - <tt>.dsc</tt></tag>
9494 This file is a control file used by <prgn>dpkg-source</prgn>
9495 to extract a source package.
9496 See <ref id="debiansourcecontrolfiles">.
9500 Original source archive -
9502 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9508 This is a compressed (with <tt>gzip -9</tt>)
9509 <prgn>tar</prgn> file containing the source code from
9510 the upstream authors of the program.
9515 Debianisation diff -
9517 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9523 This is a unified context diff (<tt>diff -u</tt>)
9524 giving the changes which are required to turn the
9525 original source into the Debian source. These changes
9526 may only include editing and creating plain files.
9527 The permissions of files, the targets of symbolic
9528 links and the characteristics of special files or
9529 pipes may not be changed and no files may be removed
9534 All the directories in the diff must exist, except the
9535 <file>debian</file> subdirectory of the top of the source
9536 tree, which will be created by
9537 <prgn>dpkg-source</prgn> if necessary when unpacking.
9541 The <prgn>dpkg-source</prgn> program will
9542 automatically make the <file>debian/rules</file> file
9543 executable (see below).</p></item>
9548 If there is no original source code - for example, if the
9549 package is specially prepared for Debian or the Debian
9550 maintainer is the same as the upstream maintainer - the
9551 format is slightly different: then there is no diff, and the
9553 <file><var>package</var>_<var>version</var>.tar.gz</file>,
9554 and preferably contains a directory named
9555 <file><var>package</var>-<var>version</var></file>.
9560 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9563 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9564 Debian source package. However, if it is not available it
9565 is possible to unpack a Debian source archive as follows:
9566 <enumlist compact="compact">
9569 Untar the tarfile, which will create a <file>.orig</file>
9573 <p>Rename the <file>.orig</file> directory to
9574 <file><var>package</var>-<var>version</var></file>.</p>
9578 Create the subdirectory <file>debian</file> at the top of
9579 the source tree.</p>
9581 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9583 <item><p>Untar the tarfile again if you want a copy of the original
9584 source code alongside the Debianised version.</p>
9589 It is not possible to generate a valid Debian source archive
9590 without using <prgn>dpkg-source</prgn>. In particular,
9591 attempting to use <prgn>diff</prgn> directly to generate the
9592 <file>.diff.gz</file> file will not work.
9596 <heading>Restrictions on objects in source packages</heading>
9599 The source package may not contain any hard links
9601 This is not currently detected when building source
9602 packages, but only when extracting
9606 Hard links may be permitted at some point in the
9607 future, but would require a fair amount of
9609 </footnote>, device special files, sockets or setuid or
9612 Setgid directories are allowed.
9617 The source packaging tools manage the changes between the
9618 original and Debianised source using <prgn>diff</prgn> and
9619 <prgn>patch</prgn>. Turning the original source tree as
9620 included in the <file>.orig.tar.gz</file> into the debianised
9621 source must not involve any changes which cannot be
9622 handled by these tools. Problematic changes which cause
9623 <prgn>dpkg-source</prgn> to halt with an error when
9624 building the source package are:
9625 <list compact="compact">
9626 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9628 <item><p>Changing the targets of symbolic links.</p>
9630 <item><p>Creating directories, other than <file>debian</file>.</p>
9632 <item><p>Changes to the contents of binary files.</p></item>
9633 </list> Changes which cause <prgn>dpkg-source</prgn> to
9634 print a warning but continue anyway are:
9635 <list compact="compact">
9638 Removing files, directories or symlinks.
9640 Renaming a file is not treated specially - it is
9641 seen as the removal of the old file (which
9642 generates a warning, but is otherwise ignored),
9643 and the creation of the new one.
9649 Changed text files which are missing the usual final
9650 newline (either in the original or the modified
9655 Changes which are not represented, but which are not detected by
9656 <prgn>dpkg-source</prgn>, are:
9657 <list compact="compact">
9658 <item><p>Changing the permissions of files (other than
9659 <file>debian/rules</file>) and directories.</p></item>
9664 The <file>debian</file> directory and <file>debian/rules</file>
9665 are handled specially by <prgn>dpkg-source</prgn> - before
9666 applying the changes it will create the <file>debian</file>
9667 directory, and afterwards it will make
9668 <file>debian/rules</file> world-exectuable.
9674 <appendix id="pkg-controlfields">
9675 <heading>Control files and their fields (from old Packaging Manual)</heading>
9678 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9679 data in a common format, known as control files. Binary and
9680 source packages have control data as do the <file>.changes</file>
9681 files which control the installation of uploaded files, and
9682 <prgn>dpkg</prgn>'s internal databases are in a similar
9687 <heading>Syntax of control files</heading>
9690 See <ref id="controlsyntax">.
9694 It is important to note that there are several fields which
9695 are optional as far as <prgn>dpkg</prgn> and the related
9696 tools are concerned, but which must appear in every Debian
9697 package, or whose omission may cause problems.
9702 <heading>List of fields</heading>
9705 See <ref id="controlfieldslist">.
9709 This section now contains only the fields that didn't belong
9710 to the Policy manual.
9713 <sect1 id="pkg-f-Filename">
9714 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9717 These fields in <tt>Packages</tt> files give the
9718 filename(s) of (the parts of) a package in the
9719 distribution directories, relative to the root of the
9720 Debian hierarchy. If the package has been split into
9721 several parts the parts are all listed in order, separated
9726 <sect1 id="pkg-f-Size">
9727 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9730 These fields in <file>Packages</file> files give the size (in
9731 bytes, expressed in decimal) and MD5 checksum of the
9732 file(s) which make(s) up a binary package in the
9733 distribution. If the package is split into several parts
9734 the values for the parts are listed in order, separated by
9739 <sect1 id="pkg-f-Status">
9740 <heading><tt>Status</tt></heading>
9743 This field in <prgn>dpkg</prgn>'s status file records
9744 whether the user wants a package installed, removed or
9745 left alone, whether it is broken (requiring
9746 reinstallation) or not and what its current state on the
9747 system is. Each of these pieces of information is a
9752 <sect1 id="pkg-f-Config-Version">
9753 <heading><tt>Config-Version</tt></heading>
9756 If a package is not installed or not configured, this
9757 field in <prgn>dpkg</prgn>'s status file records the last
9758 version of the package which was successfully
9763 <sect1 id="pkg-f-Conffiles">
9764 <heading><tt>Conffiles</tt></heading>
9767 This field in <prgn>dpkg</prgn>'s status file contains
9768 information about the automatically-managed configuration
9769 files held by a package. This field should <em>not</em>
9770 appear anywhere in a package!
9775 <heading>Obsolete fields</heading>
9778 These are still recognised by <prgn>dpkg</prgn> but should
9779 not appear anywhere any more.
9781 <taglist compact="compact">
9783 <tag><tt>Revision</tt></tag>
9784 <tag><tt>Package-Revision</tt></tag>
9785 <tag><tt>Package_Revision</tt></tag>
9787 The Debian revision part of the package version was
9788 at one point in a separate control file field. This
9789 field went through several names.
9792 <tag><tt>Recommended</tt></tag>
9793 <item>Old name for <tt>Recommends</tt>.</item>
9795 <tag><tt>Optional</tt></tag>
9796 <item>Old name for <tt>Suggests</tt>.</item>
9798 <tag><tt>Class</tt></tag>
9799 <item>Old name for <tt>Priority</tt>.</item>
9808 <appendix id="pkg-conffiles">
9809 <heading>Configuration file handling (from old Packaging Manual)</heading>
9812 <prgn>dpkg</prgn> can do a certain amount of automatic
9813 handling of package configuration files.
9817 Whether this mechanism is appropriate depends on a number of
9818 factors, but basically there are two approaches to any
9819 particular configuration file.
9823 The easy method is to ship a best-effort configuration in the
9824 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9825 handle updates. If the user is unlikely to want to edit the
9826 file, but you need them to be able to without losing their
9827 changes, and a new package with a changed version of the file
9828 is only released infrequently, this is a good approach.
9832 The hard method is to build the configuration file from
9833 scratch in the <prgn>postinst</prgn> script, and to take the
9834 responsibility for fixing any mistakes made in earlier
9835 versions of the package automatically. This will be
9836 appropriate if the file is likely to need to be different on
9840 <sect><heading>Automatic handling of configuration files by
9845 A package may contain a control area file called
9846 <tt>conffiles</tt>. This file should be a list of filenames
9847 of configuration files needing automatic handling, separated
9848 by newlines. The filenames should be absolute pathnames,
9849 and the files referred to should actually exist in the
9854 When a package is upgraded <prgn>dpkg</prgn> will process
9855 the configuration files during the configuration stage,
9856 shortly before it runs the package's <prgn>postinst</prgn>
9861 For each file it checks to see whether the version of the
9862 file included in the package is the same as the one that was
9863 included in the last version of the package (the one that is
9864 being upgraded from); it also compares the version currently
9865 installed on the system with the one shipped with the last
9870 If neither the user nor the package maintainer has changed
9871 the file, it is left alone. If one or the other has changed
9872 their version, then the changed version is preferred - i.e.,
9873 if the user edits their file, but the package maintainer
9874 doesn't ship a different version, the user's changes will
9875 stay, silently, but if the maintainer ships a new version
9876 and the user hasn't edited it the new version will be
9877 installed (with an informative message). If both have
9878 changed their version the user is prompted about the problem
9879 and must resolve the differences themselves.
9883 The comparisons are done by calculating the MD5 message
9884 digests of the files, and storing the MD5 of the file as it
9885 was included in the most recent version of the package.
9889 When a package is installed for the first time
9890 <prgn>dpkg</prgn> will install the file that comes with it,
9891 unless that would mean overwriting a file already on the
9896 However, note that <prgn>dpkg</prgn> will <em>not</em>
9897 replace a conffile that was removed by the user (or by a
9898 script). This is necessary because with some programs a
9899 missing file produces an effect hard or impossible to
9900 achieve in another way, so that a missing file needs to be
9901 kept that way if the user did it.
9905 Note that a package should <em>not</em> modify a
9906 <prgn>dpkg</prgn>-handled conffile in its maintainer
9907 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9908 the user confusing and possibly dangerous options for
9909 conffile update when the package is upgraded.</p>
9912 <sect><heading>Fully-featured maintainer script configuration
9917 For files which contain site-specific information such as
9918 the hostname and networking details and so forth, it is
9919 better to create the file in the package's
9920 <prgn>postinst</prgn> script.
9924 This will typically involve examining the state of the rest
9925 of the system to determine values and other information, and
9926 may involve prompting the user for some information which
9927 can't be obtained some other way.
9931 When using this method there are a couple of important
9932 issues which should be considered:
9936 If you discover a bug in the program which generates the
9937 configuration file, or if the format of the file changes
9938 from one version to the next, you will have to arrange for
9939 the postinst script to do something sensible - usually this
9940 will mean editing the installed configuration file to remove
9941 the problem or change the syntax. You will have to do this
9942 very carefully, since the user may have changed the file,
9943 perhaps to fix the very problem that your script is trying
9944 to deal with - you will have to detect these situations and
9945 deal with them correctly.
9949 If you do go down this route it's probably a good idea to
9950 make the program that generates the configuration file(s) a
9951 separate program in <file>/usr/sbin</file>, by convention called
9952 <file><var>package</var>config</file> and then run that if
9953 appropriate from the post-installation script. The
9954 <tt><var>package</var>config</tt> program should not
9955 unquestioningly overwrite an existing configuration - if its
9956 mode of operation is geared towards setting up a package for
9957 the first time (rather than any arbitrary reconfiguration
9958 later) you should have it check whether the configuration
9959 already exists, and require a <tt>--force</tt> flag to
9960 overwrite it.</p></sect>
9963 <appendix id="pkg-alternatives"><heading>Alternative versions of
9964 an interface - <prgn>update-alternatives</prgn> (from old
9969 When several packages all provide different versions of the
9970 same program or file it is useful to have the system select a
9971 default, but to allow the system administrator to change it
9972 and have their decisions respected.
9976 For example, there are several versions of the <prgn>vi</prgn>
9977 editor, and there is no reason to prevent all of them from
9978 being installed at once, each under their own name
9979 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9980 Nevertheless it is desirable to have the name <tt>vi</tt>
9981 refer to something, at least by default.
9985 If all the packages involved cooperate, this can be done with
9986 <prgn>update-alternatives</prgn>.
9990 Each package provides its own version under its own name, and
9991 calls <prgn>update-alternatives</prgn> in its postinst to
9992 register its version (and again in its prerm to deregister
9997 See the man page <manref name="update-alternatives"
9998 section="8"> for details.
10002 If <prgn>update-alternatives</prgn> does not seem appropriate
10003 you may wish to consider using diversions instead.</p>
10006 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10007 package's version of a file (from old Packaging Manual)
10011 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10012 when it reinstalls the package it belongs to, and to have it
10013 put the file from the package somewhere else instead.
10017 This can be used locally to override a package's version of a
10018 file, or by one package to override another's version (or
10019 provide a wrapper for it).
10023 Before deciding to use a diversion, read <ref
10024 id="pkg-alternatives"> to see if you really want a diversion
10025 rather than several alternative versions of a program.
10029 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10030 and updated by a special program <prgn>dpkg-divert</prgn>.
10031 Please see <manref name="dpkg-divert" section="8"> for full
10032 details of its operation.
10036 When a package wishes to divert a file from another, it should
10037 call <prgn>dpkg-divert</prgn> in its preinst to add the
10038 diversion and rename the existing file. For example,
10039 supposing that a <prgn>smailwrapper</prgn> package wishes to
10040 install a wrapper around <file>/usr/sbin/smail</file>:
10042 if [ install = "$1" ]; then
10043 dpkg-divert --package smailwrapper --add --rename \
10044 --divert /usr/sbin/smail.real /usr/sbin/smail
10046 </example> Testing <tt>$1</tt> is necessary so that the script
10047 doesn't try to add the diversion again when
10048 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10049 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10050 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10051 get installed as the true version.
10055 The postrm has to do the reverse:
10057 if [ remove = "$1" ]; then
10058 dpkg-divert --package smailwrapper --remove --rename \
10059 --divert /usr/sbin/smail.real /usr/sbin/smail
10065 Do not attempt to divert a file which is vitally important for
10066 the system's operation - when using <prgn>dpkg-divert</prgn>
10067 there is a time, after it has been diverted but before
10068 <prgn>dpkg</prgn> has installed the new version, when the file
10069 does not exist.</p>
10074 <!-- vim:set ai et sts=2 sw=2 tw=76: -->