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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy" id="http://packages.debian.org/debian-policy"></package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>.
168 Also available from the same directory are several other
169 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
170 and <file>policy.ps.gz</file>.
174 The <package>debian-policy</package> package also includes the file
175 <file>upgrading-checklist.txt</file> which indicates policy
176 changes between versions of this document.
181 <heading>Authors and Maintainers</heading>
184 Originally called "Debian GNU/Linux Policy Manual", this
185 manual was initially written in 1996 by Ian Jackson.
186 It was revised on November 27th, 1996 by David A. Morris.
187 Christian Schwarz added new sections on March 15th, 1997,
188 and reworked/restructured it in April-July 1997.
189 Christoph Lameter contributed the "Web Standard".
190 Julian Gilbey largely restructured it in 2001.
194 Since September 1998, the responsibility for the contents of
195 this document lies on the <url name="debian-policy mailing list"
196 id="mailto:debian-policy@lists.debian.org">. Proposals
197 are discussed there and inserted into policy after a certain
198 consensus is established.
199 <!-- insert shameless policy-process plug here eventually -->
200 The actual editing is done by a group of maintainers that have
201 no editorial powers. These are the current maintainers:
204 <item>Julian Gilbey</item>
205 <item>Branden Robinson</item>
206 <item>Josip Rodin</item>
207 <item>Manoj Srivastava</item>
212 While the authors of this document have tried hard to avoid
213 typos and other errors, these do still occur. If you discover
214 an error in this manual or if you want to give any
215 comments, suggestions, or criticisms please send an email to
216 the Debian Policy List,
217 <email>debian-policy@lists.debian.org</email>, or submit a
218 bug report against the <tt>debian-policy</tt> package.
222 Please do not try to reach the individual authors or maintainers
223 of the Policy Manual regarding changes to the Policy.
228 <heading>Related documents</heading>
231 There are several other documents other than this Policy Manual
232 that are necessary to fully understand some Debian policies and
237 The external "sub-policy" documents are referred to in:
238 <list compact="compact">
239 <item><ref id="fhs"></item>
240 <item><ref id="virtual_pkg"></item>
241 <item><ref id="menus"></item>
242 <item><ref id="mime"></item>
243 <item><ref id="perl"></item>
244 <item><ref id="maintscriptprompt"></item>
245 <item><ref id="emacs"></item>
250 In addition to those, which carry the weight of policy, there
251 is the Debian Developer's Reference. This document describes
252 procedures and resources for Debian developers, but it is
253 <em>not</em> normative; rather, it includes things that don't
254 belong in the Policy, such as best practices for developers.
258 The Developer's Reference is available in the
259 <package>developers-reference</package> package.
260 It's also available from the Debian web mirrors at
261 <tt><url name="/doc/developers-reference/"
262 id="http://www.debian.org/doc/developers-reference/"></tt>.
270 <heading>The Debian Archive</heading>
273 The Debian GNU/Linux system is maintained and distributed as a
274 collection of <em>packages</em>. Since there are so many of
275 them (currently well over 6000), they are split into
276 <em>sections</em> and given <em>priorities</em> to simplify
277 the handling of them.
281 The effort of the Debian project is to build a free operating
282 system, but not every package we want to make accessible is
283 <em>free</em> in our sense (see the Debian Free Software
284 Guidelines, below), or may be imported/exported without
285 restrictions. Thus, the archive is split into the sections
286 based on their licenses and other restrictions.
290 The aims of this are:
292 <list compact="compact">
293 <item>to allow us to make as much software available as we can</item>
294 <item>to allow us to encourage everyone to write free software,
296 <item>to allow us to make it easy for people to produce
297 CD-ROMs of our system without violating any licenses,
298 import/export restrictions, or any other laws.</item>
303 The <em>main</em> and the <em>non-US/main</em> sections
304 together form the <em>Debian GNU/Linux distribution</em>.
308 Packages in the other sections are not considered to be part
309 of the Debian distribution, although we support their use and
310 provide infrastructure for them (such as our bug-tracking
311 system and mailing lists). This Debian Policy Manual applies
312 to these packages as well.
316 <heading>The Debian Free Software Guidelines</heading>
318 The Debian Free Software Guidelines (DFSG) form our
319 definition of "free software". These are:
321 <tag>Free Redistribution
324 The license of a Debian component may not restrict any
325 party from selling or giving away the software as a
326 component of an aggregate software distribution
327 containing programs from several different
328 sources. The license may not require a royalty or
329 other fee for such sale.
334 The program must include source code, and must allow
335 distribution in source code as well as compiled form.
340 The license must allow modifications and derived
341 works, and must allow them to be distributed under the
342 same terms as the license of the original software.
344 <tag>Integrity of The Author's Source Code
347 The license may restrict source-code from being
348 distributed in modified form <em>only</em> if the
349 license allows the distribution of "patch files"
350 with the source code for the purpose of modifying the
351 program at build time. The license must explicitly
352 permit distribution of software built from modified
353 source code. The license may require derived works to
354 carry a different name or version number from the
355 original software. (This is a compromise. The Debian
356 Project encourages all authors to not restrict any
357 files, source or binary, from being modified.)
359 <tag>No Discrimination Against Persons or Groups
362 The license must not discriminate against any person
365 <tag>No Discrimination Against Fields of Endeavor
368 The license must not restrict anyone from making use
369 of the program in a specific field of endeavor. For
370 example, it may not restrict the program from being
371 used in a business, or from being used for genetic
374 <tag>Distribution of License
377 The rights attached to the program must apply to all
378 to whom the program is redistributed without the need
379 for execution of an additional license by those
382 <tag>License Must Not Be Specific to Debian
385 The rights attached to the program must not depend on
386 the program's being part of a Debian system. If the
387 program is extracted from Debian and used or
388 distributed without Debian but otherwise within the
389 terms of the program's license, all parties to whom
390 the program is redistributed must have the same
391 rights as those that are granted in conjunction with
394 <tag>License Must Not Contaminate Other Software
397 The license must not place restrictions on other
398 software that is distributed along with the licensed
399 software. For example, the license must not insist
400 that all other programs distributed on the same medium
401 must be free software.
403 <tag>Example Licenses
406 The "GPL," "BSD," and "Artistic" licenses are examples of
407 licenses that we consider <em>free</em>.
414 <heading>Sections</heading>
417 <heading>The main section</heading>
420 Every package in <em>main</em> and <em>non-US/main</em>
421 must comply with the DFSG (Debian Free Software
426 In addition, the packages in <em>main</em>
427 <list compact="compact">
429 must not require a package outside of <em>main</em>
430 for compilation or execution (thus, the package must
431 not declare a "Depends", "Recommends", or
432 "Build-Depends" relationship on a non-<em>main</em>
436 must not be so buggy that we refuse to support them,
440 must meet all policy requirements presented in this
447 Similarly, the packages in <em>non-US/main</em>
448 <list compact="compact">
450 must not require a package outside of <em>main</em>
451 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
458 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
479 must not be so buggy that we refuse to support them,
483 must meet all policy requirements presented in this
490 Furthermore, packages in <em>contrib</em> must not require
491 a package in a <em>non-US</em> section for compilation or
496 Examples of packages which would be included in
497 <em>contrib</em> or <em>non-US/contrib</em> are:
498 <list compact="compact">
500 free packages which require <em>contrib</em>,
501 <em>non-free</em> packages or packages which are not
502 in our archive at all for compilation or execution,
506 wrapper packages or other sorts of free accessories for
513 <sect1 id="non-free">
514 <heading>The non-free section</heading>
517 Packages must be placed in <em>non-free</em> or
518 <em>non-US/non-free</em> if they are not compliant with
519 the DFSG or are encumbered by patents or other legal
520 issues that make their distribution problematic.
524 In addition, the packages in <em>non-free</em> and
525 <em>non-US/non-free</em>
526 <list compact="compact">
528 must not be so buggy that we refuse to support them,
532 must meet all policy requirements presented in this
533 manual that it is possible for them to meet.
535 It is possible that there are policy
536 requirements which the package is unable to
537 meet, for example, if the source is
538 unavailable. These situations will need to be
539 handled on a case-by-case basis.
547 <heading>The non-US sections</heading>
550 Non-free programs with cryptographic program code need to
551 be stored on the <em>non-us</em> server because of export
552 restrictions of the U.S.
556 Programs which use patented algorithms that have a
557 restricted license also need to be stored on "non-us",
558 since the non-us archive is located in a country where
559 patenting algorithms is not allowed.
563 A package depends on another package which is distributed
564 via the non-us server has to be stored on the non-us
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of
575 its copyright and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Subsections</heading>
653 The packages in the sections <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further
655 into <em>subsections</em> to simplify handling.
659 The section and subsection for each package should be
660 specified in the package's <tt>Section</tt> control
661 record (see <ref id="f-Section">).
662 However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
668 <em>subsection</em> if the package is in the
669 <em>main</em> section,
672 <em>section/subsection</em> if the package is in
673 the <em>contrib</em> or <em>non-free</em> section,
677 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
678 <tt>non-US/non-free</tt> if the package is in
679 <em>non-US/main</em>, <em>non-US/contrib</em> or
680 <em>non-US/non-free</em> respectively.
686 The Debian archive maintainers provide the authoritative
687 list of subsections. At present, they are:
688 <em>admin</em>, <em>base</em>, <em>comm</em>,
689 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
690 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
691 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
692 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
693 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
694 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
695 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
696 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
697 <em>science</em>, <em>shells</em>,
698 <em>sound</em>, <em>tex</em>, <em>text</em>,
699 <em>utils</em>, <em>web</em>, <em>x11</em>.
703 <sect id="priorities">
704 <heading>Priorities</heading>
707 Each package should have a <em>priority</em> value, which is
708 included in the package's <em>control record</em>
709 (see <ref id="f-Priority">).
710 This information is used by the Debian package management tools to
711 separate high-priority packages from less-important packages.
715 The following <em>priority levels</em> are recognised by the
716 Debian package management tools.
718 <tag><tt>required</tt></tag>
720 Packages which are necessary for the proper
721 functioning of the system. You must not remove these
722 packages or your system may become totally broken and
723 you may not even be able to use <prgn>dpkg</prgn> to
724 put things back. Systems with only the
725 <tt>required</tt> packages are probably unusable, but
726 they do have enough functionality to allow the
727 sysadmin to boot and install more software.
729 <tag><tt>important</tt></tag>
731 Important programs, including those which one would
732 expect to find on any Unix-like system. If the
733 expectation is that an experienced Unix person who
734 found it missing would say "What on earth is going on,
735 where is <prgn>foo</prgn>?", it must be an
736 <tt>important</tt> package.<footnote>
737 This is an important criterion because we are
738 trying to produce, amongst other things, a free
741 Other packages without which the system will not run
742 well or be usable must also have priority
743 <tt>important</tt>. This does
744 <em>not</em> include Emacs, the X Window System, TeX
745 or any other large applications. The
746 <tt>important</tt> packages are just a bare minimum of
747 commonly-expected and necessary tools.
749 <tag><tt>standard</tt></tag>
751 These packages provide a reasonably small but not too
752 limited character-mode system. This is what will be
753 installed by default if the user doesn't select anything
754 else. It doesn't include many large applications.
756 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
767 <tag><tt>extra</tt></tag>
769 This contains all packages that conflict with others
770 with required, important, standard or optional
771 priorities, or are only likely to be useful if you
772 already know what they are or have specialised
779 Packages must not depend on packages with lower priority
780 values (excluding build-time dependencies). In order to
781 ensure this, the priorities of one or more packages may need
790 <heading>Binary packages</heading>
793 The Debian GNU/Linux distribution is based on the Debian
794 package management system, called <prgn>dpkg</prgn>. Thus,
795 all packages in the Debian distribution must be provided
796 in the <tt>.deb</tt> file format.
800 <heading>The package name</heading>
803 Every package must have a name that's unique within the Debian
808 The package name is included in the control field
809 <tt>Package</tt>, the format of which is described
810 in <ref id="f-Package">.
811 The package name is also included as a part of the file name
812 of the <tt>.deb</tt> file.
817 <heading>The version of a package</heading>
820 Every package has a version number recorded in its
821 <tt>Version</tt> control file field, described in
822 <ref id="f-Version">.
826 The package management system imposes an ordering on version
827 numbers, so that it can tell whether packages are being up- or
828 downgraded and so that package system front end applications
829 can tell whether a package it finds available is newer than
830 the one installed on the system. The version number format
831 has the most significant parts (as far as comparison is
832 concerned) at the beginning.
836 If an upstream package has problematic version numbers they
837 should be converted to a sane form for use in the
838 <tt>Version</tt> field.
842 <heading>Version numbers based on dates</heading>
845 In general, Debian packages should use the same version
846 numbers as the upstream sources.
850 However, in some cases where the upstream version number is
851 based on a date (e.g., a development "snapshot" release) the
852 package management system cannot handle these version
853 numbers without epochs. For example, dpkg will consider
854 "96May01" to be greater than "96Dec24".
858 To prevent having to use epochs for every new upstream
859 version, the date based portion of the version number
860 should be changed to the following format in such cases:
861 "19960501", "19961224". It is up to the maintainer whether
862 they want to bother the upstream maintainer to change
863 the version numbers upstream, too.
867 Note that other version formats based on dates which are
868 parsed correctly by the package management system should
869 <em>not</em> be changed.
873 Native Debian packages (i.e., packages which have been
874 written especially for Debian) whose version numbers include
875 dates should always use the "YYYYMMDD" format.
882 <heading>The maintainer of a package</heading>
885 Every package must have a Debian maintainer (the
886 maintainer may be one person or a group of people
887 reachable from a common email address, such as a mailing
888 list). The maintainer is responsible for ensuring that
889 the package is placed in the appropriate distributions.
893 The maintainer must be specified in the
894 <tt>Maintainer</tt> control field with their correct name
895 and a working email address. If one person maintains
896 several packages, they should try to avoid having
897 different forms of their name and email address in
898 the <tt>Maintainer</tt> fields of those packages.
902 The format of the <tt>Maintainer</tt> control field is
903 described in <ref id="f-Maintainer">.
907 If the maintainer of a package quits from the Debian
908 project, "Debian QA Group"
909 <email>packages@qa.debian.org</email> takes over the
910 maintainership of the package until someone else
911 volunteers for that task. These packages are called
912 <em>orphaned packages</em>.<footnote>
913 The detailed procedure for doing this gracefully can
914 be found in the Debian Developer's Reference,
915 see <ref id="related">.
920 <sect id="descriptions">
921 <heading>The description of a package</heading>
924 Every Debian package must have an extended description
925 stored in the appropriate field of the control record.
926 The technical information about the format of the
927 <tt>Description</tt> field is in <ref id="f-Description">.
931 The description should describe the package (the program) to a
932 user (system administrator) who has never met it before so that
933 they have enough information to decide whether they want to
934 install it. This description should not just be copied verbatim
935 from the program's documentation.
939 Put important information first, both in the synopsis and
940 extended description. Sometimes only the first part of the
941 synopsis or of the description will be displayed. You can
942 assume that there will usually be a way to see the whole
943 extended description.
947 The description should also give information about the
948 significant dependencies and conflicts between this package
949 and others, so that the user knows why these dependencies and
950 conflicts have been declared.
954 Instructions for configuring or using the package should
955 not be included (that is what installation scripts,
956 manual pages, info files, etc., are for). Copyright
957 statements and other administrivia should not be included
958 either (that is what the copyright file is for).
961 <sect1 id="synopsis"><heading>The single line synopsis</heading>
964 The single line synopsis should be kept brief - certainly
969 Do not include the package name in the synopsis line. The
970 display software knows how to display this already, and you
971 do not need to state it. Remember that in many situations
972 the user may only see the synopsis line - make it as
973 informative as you can.
978 <sect1 id="extendeddesc"><heading>The extended description</heading>
981 Do not try to continue the single line synopsis into the
982 extended description. This will not work correctly when
983 the full description is displayed, and makes no sense
984 where only the summary (the single line synopsis) is
989 The extended description should describe what the package
990 does and how it relates to the rest of the system (in terms
991 of, for example, which subsystem it is which part of).
995 The description field needs to make sense to anyone, even
996 people who have no idea about any of the things the
997 package deals with.<footnote>
998 The blurb that comes with a program in its
999 announcements and/or <prgn>README</prgn> files is
1000 rarely suitable for use in a description. It is
1001 usually aimed at people who are already in the
1002 community where the package is used.
1011 <heading>Dependencies</heading>
1014 Every package must specify the dependency information
1015 about other packages that are required for the first to
1020 For example, a dependency entry must be provided for any
1021 shared libraries required by a dynamically-linked executable
1022 binary in a package.
1026 Packages are not required to declare any dependencies they
1027 have on other packages which are marked <tt>Essential</tt>
1028 (see below), and should not do so unless they depend on a
1029 particular version of that package.
1033 Sometimes, a package requires another package to be installed
1034 <em>and</em> configured before it can be installed. In this
1035 case, you must specify a <tt>Pre-Depends</tt> entry for
1040 You should not specify a <tt>Pre-Depends</tt> entry for a
1041 package before this has been discussed on the
1042 <tt>debian-devel</tt> mailing list and a consensus about
1043 doing that has been reached.
1047 The format of the package interrelationship control fields is
1048 described in <ref id="relationships">.
1052 <sect id="virtual_pkg">
1053 <heading>Virtual packages</heading>
1056 Sometimes, there are several packages which offer
1057 more-or-less the same functionality. In this case, it's
1058 useful to define a <em>virtual package</em> whose name
1059 describes that common functionality. (The virtual
1060 packages only exist logically, not physically; that's why
1061 they are called <em>virtual</em>.) The packages with this
1062 particular function will then <em>provide</em> the virtual
1063 package. Thus, any other package requiring that function
1064 can simply depend on the virtual package without having to
1065 specify all possible packages individually.
1069 All packages should use virtual package names where
1070 appropriate, and arrange to create new ones if necessary.
1071 They should not use virtual package names (except privately,
1072 amongst a cooperating group of packages) unless they have
1073 been agreed upon and appear in the list of virtual package
1074 names. (See also <ref id="virtual">)
1078 The latest version of the authoritative list of virtual
1079 package names can be found in the <tt>debian-policy</tt> package.
1080 It is also available from the Debian web mirrors at
1081 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1082 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1086 The procedure for updating the list is described in the preface
1093 <heading>Base system</heading>
1096 The <tt>base system</tt> is a minimum subset of the Debian
1097 GNU/Linux system that is installed before everything else
1098 on a new system. Thus, only very few packages are allowed
1099 to go into the <tt>base</tt> section to keep the required
1100 disk usage very small.
1104 Most of these packages will have the priority value
1105 <tt>required</tt> or at least <tt>important</tt>, and many
1106 of them will be tagged <tt>essential</tt> (see below).
1111 <heading>Essential packages</heading>
1114 Some packages are tagged <tt>essential</tt> for a system
1115 using the <tt>Essential</tt> control file field.
1116 The format of the <tt>Essential</tt> control field is
1117 described in <ref id="f-Essential">.
1121 Since these packages cannot be easily removed (one has to
1122 specify an extra <em>force option</em> to
1123 <prgn>dpkg</prgn> to do so), this flag must not be used
1124 unless absolutely necessary. A shared library package
1125 must not be tagged <tt>essential</tt>; dependencies will
1126 prevent its premature removal, and we need to be able to
1127 remove it when it has been superseded.
1131 Since dpkg will not prevent upgrading of other packages
1132 while an <tt>essential</tt> package is in an unconfigured
1133 state, all <tt>essential</tt> packages must supply all of
1134 their core functionality even when unconfigured. If the
1135 package cannot satisfy this requirement it must not be
1136 tagged as essential, and any packages depending on this
1137 package must instead have explicit dependency fields as
1142 You must not tag any packages <tt>essential</tt> before
1143 this has been discussed on the <tt>debian-devel</tt>
1144 mailing list and a consensus about doing that has been
1150 <heading>Tasks</heading>
1153 The Debian install process allows the user to choose from
1154 a number of common tasks which a Debian system can be used to
1155 perform. Selecting a task with <prgn>tasksel</prgn> causes
1156 a set of packages that are useful in performing that task to be
1161 This set of packages is all available packages which have the
1162 name of the selected task in the <tt>Task</tt> field of their
1163 control file. The format of this field is a list of tasks,
1164 separated by commas.
1168 You should not tag any packages as belonging to a task
1169 before this has been discussed on the
1170 <em>debian-devel</em> mailing list and a consensus about
1171 doing that has been reached.
1175 For third parties (and historical reasons), tasksel also
1176 supports constructing tasks based on <em>task
1177 packages</em>. These are packages whose names begin with
1178 <em>task-</em>. Task packages should not be included in the
1183 <sect id="maintscripts">
1184 <heading>Maintainer Scripts</heading>
1187 The package installation scripts should avoid producing
1188 output which is unnecessary for the user to see and
1189 should rely on <prgn>dpkg</prgn> to stave off boredom on
1190 the part of a user installing many packages. This means,
1191 amongst other things, using the <tt>--quiet</tt> option on
1192 <prgn>install-info</prgn>.
1196 Errors which occur during the execution of an installation
1197 script must be checked and the installation must not
1198 continue after an error.
1202 Note that in general <ref id="scripts"> applies to package
1203 maintainer scripts, too.
1207 You should not use <prgn>dpkg-divert</prgn> on a file
1208 belonging to another package without consulting the
1209 maintainer of that package first.
1213 All packages which supply an instance of a common command
1214 name (or, in general, filename) should generally use
1215 <prgn>update-alternatives</prgn>, so that they may be
1216 installed together. If <prgn>update-alternatives</prgn>
1217 is not used, then each package must use
1218 <tt>Conflicts</tt> to ensure that other packages are
1219 de-installed. (In this case, it may be appropriate to
1220 specify a conflict against earlier versions of something
1221 that previously did not use
1222 <prgn>update-alternatives</prgn>; this is an exception to
1223 the usual rule that versioned conflicts should be
1227 <sect1 id="maintscriptprompt">
1228 <heading>Prompting in maintainer scripts</heading>
1230 Package maintainer scripts may prompt the user if
1231 necessary. Prompting should be done by communicating
1232 through a program, such as <prgn>debconf</prgn>, which
1233 conforms to the Debian Configuration management
1234 specification, version 2 or higher. Prompting the user by
1235 other means, such as by hand<footnote>
1236 From the Jargon file: by hand 2. By extension,
1237 writing code which does something in an explicit or
1238 low-level way for which a presupplied library
1239 (<em>debconf, in this instance</em>) routine ought
1240 to have been available.
1241 </footnote>, is now deprecated.
1245 The Debian Configuration management specification is included
1246 in the <file>debconf_specification</file> files in the
1247 <package>debian-policy</package> package.
1248 It is also available from the Debian web mirrors at
1249 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1250 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1254 Packages which use the Debian Configuration management
1255 specification may contain an additional
1256 <prgn>config</prgn> script and a <tt>templates</tt>
1257 file in their control archive<footnote>
1258 The control.tar.gz inside the .deb.
1259 See <manref name="deb" section="5">.
1261 The <prgn>config</prgn> script might be run before the
1262 <prgn>preinst</prgn> script, and before the package is unpacked
1263 or any of its dependencies or pre-dependancies are satisfied.
1264 Therefore it must work using only the tools present in
1265 <em>essential</em> packages.<footnote>
1266 <package>Debconf</package> or another tool that
1267 implements the Debian Configuration management
1268 specification will also be installed, and any
1269 versioned dependencies on it will be satisfied
1270 before preconfiguration begins.
1275 Packages should try to minimize the amount of prompting
1276 they need to do, and they should ensure that the user
1277 will only ever be asked each question once. This means
1278 that packages should try to use appropriate shared
1279 configuration files (such as <file>/etc/papersize</file> and
1280 <file>/etc/news/server</file>), and shared
1281 <package>debconf</package> variables rather than each
1282 prompting for their own list of required pieces of
1287 It also means that an upgrade should not ask the same
1288 questions again, unless the user has used
1289 <tt>dpkg --purge</tt> to remove the package's configuration.
1290 The answers to configuration questions should be stored in an
1291 appropriate place in <file>/etc</file> so that the user can
1292 modify them, and how this has been done should be
1297 If a package has a vitally important piece of
1298 information to pass to the user (such as "don't run me
1299 as I am, you must edit the following configuration files
1300 first or you risk your system emitting badly-formatted
1301 messages"), it should display this in the
1302 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1303 prompt the user to hit return to acknowledge the
1304 message. Copyright messages do not count as vitally
1305 important (they belong in
1306 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1307 neither do instructions on how to use a program (these
1308 should be in on-line documentation, where all the users
1313 Any necessary prompting should almost always be confined
1314 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1315 script. If it is done in the <prgn>postinst</prgn>, it
1316 should be protected with a conditional so that
1317 unnecessary prompting doesn't happen if a package's
1318 installation fails and the <prgn>postinst</prgn> is
1319 called with <tt>abort-upgrade</tt>,
1320 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1330 <heading>Source packages</heading>
1332 <sect id="standardsversion">
1333 <heading>Standards conformance</heading>
1336 Source packages should specify the most recent version number
1337 of this policy document with which your package complied
1338 when it was last updated.
1342 This information may be used to file bug reports
1343 automatically if your package becomes too much out of date.
1347 The version is specified in the <tt>Standards-Version</tt>
1349 The format of the <tt>Standards-Version</tt> field is
1350 described in <ref id="f-Standards-Version">.
1354 You should regularly, and especially if your package has
1355 become out of date, check for the newest Policy Manual
1356 available and update your package, if necessary. When your
1357 package complies with the new standards you should update the
1358 <tt>Standards-Version</tt> source package field and
1359 release it.<footnote>
1360 See the file <file>upgrading-checklist</file> for
1361 information about policy which has changed between
1362 different versions of this document.
1368 <sect id="pkg-relations">
1369 <heading>Package relationships</heading>
1372 Source packages should specify which binary packages they
1373 require to be installed or not to be installed in order to
1374 build correctly. For example, if building a package
1375 requires a certain compiler, then the compiler should be
1376 specified as a build-time dependency.
1380 It is not necessary to explicitly specify build-time
1381 relationships on a minimal set of packages that are always
1382 needed to compile, link and put in a Debian package a
1383 standard "Hello World!" program written in C or C++. The
1384 required packages are called <em>build-essential</em>, and
1385 an informational list can be found in
1386 <file>/usr/share/doc/build-essential/list</file> (which is
1387 contained in the <tt>build-essential</tt>
1390 <list compact="compact">
1392 This allows maintaining the list separately
1393 from the policy documents (the list does not
1394 need the kind of control that the policy
1398 Having a separate package allows one to install
1399 the build-essential packages on a machine, as
1400 well as allowing other packages such as tasks to
1401 require installation of the build-essential
1402 packages using the depends relation.
1405 The separate package allows bug reports against
1406 the list to be categorized separately from
1407 the policy management process in the BTS.
1414 When specifying the set of build-time dependencies, one
1415 should list only those packages explicitly required by the
1416 build. It is not necessary to list packages which are
1417 required merely because some other package in the list of
1418 build-time dependencies depends on them.<footnote>
1419 The reason for this is that dependencies change, and
1420 you should list all those packages, and <em>only</em>
1421 those packages that <em>you</em> need directly. What
1422 others need is their business. For example, if you
1423 only link against <file>libimlib</file>, you will need to
1424 build-depend on <package>libimlib2-dev</package> but
1425 not against any <tt>libjpeg*</tt> packages, even
1426 though <tt>libimlib2-dev</tt> currently depends on
1427 them: installation of <package>libimlib2-dev</package>
1428 will automatically ensure that all of its run-time
1429 dependencies are satisfied.
1434 If build-time dependencies are specified, it must be
1435 possible to build the package and produce working binaries
1436 on a system with only essential and build-essential
1437 packages installed and also those required to satisfy the
1438 build-time relationships (including any implied
1439 relationships). In particular, this means that version
1440 clauses should be used rigorously in build-time
1441 relationships so that one cannot produce bad or
1442 inconsistently configured packages when the relationships
1443 are properly satisfied.
1447 <ref id="relationships"> explains the technical details.
1452 <heading>Changes to the upstream sources</heading>
1455 If changes to the source code are made that are not
1456 specific to the needs of the Debian system, they should be
1457 sent to the upstream authors in whatever form they prefer
1458 so as to be included in the upstream version of the
1463 If you need to configure the package differently for
1464 Debian or for Linux, and the upstream source doesn't
1465 provide a way to do so, you should add such configuration
1466 facilities (for example, a new <prgn>autoconf</prgn> test
1467 or <tt>#define</tt>) and send the patch to the upstream
1468 authors, with the default set to the way they originally
1469 had it. You can then easily override the default in your
1470 <file>debian/rules</file> or wherever is appropriate.
1474 You should make sure that the <prgn>configure</prgn> utility
1475 detects the correct architecture specification string
1476 (refer to <ref id="arch-spec"> for details).
1480 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1481 <prgn>configure</prgn> scripts are used, you should edit the
1482 <file>.in</file> files rather than editing the
1483 <prgn>Makefile</prgn> directly. This allows the user to
1484 reconfigure the package if necessary. You should
1485 <em>not</em> configure the package and edit the generated
1486 <prgn>Makefile</prgn>! This makes it impossible for someone
1487 else to later reconfigure the package without losing the
1493 <sect id="dpkgchangelog">
1494 <heading>Debian changelog: <file>debian/changelog</file></heading>
1497 Changes in the Debian version of the package should be
1498 briefly explained in the Debian changelog file
1499 <file>debian/changelog</file>. This includes modifications
1500 made in the Debian package compared to the upstream one
1501 as well as other changes and updates to the package.
1503 Although there is nothing stopping an author who is also
1504 the Debian maintainer from using this changelog for all
1505 their changes, it will have to be renamed if the Debian
1506 and upstream maintainers become different people. In such
1507 a case, however, it might be better to maintain the package
1508 as a non-native package.
1513 Mistakes in changelogs are usually best rectified by making
1514 a new changelog entry rather than "rewriting history" by
1515 editing old changelog entries.
1519 The format of the <file>debian/changelog</file> allows the
1520 package building tools to discover which version of the package
1521 is being built and find out other release-specific information.
1525 That format is a series of entries like this:
1527 <example compact="compact">
1528 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1530 [optional blank line(s), stripped]
1532 * <var>change details</var>
1533 <var>more change details</var>
1535 [blank line(s), included in output of dpkg-parsechangelog]
1537 * <var>even more change details</var>
1539 [optional blank line(s), stripped]
1541 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1546 <var>package</var> and <var>version</var> are the source
1547 package name and version number.
1551 <var>distribution(s)</var> lists the distributions where
1552 this version should be installed when it is uploaded - it
1553 is copied to the <tt>Distribution</tt> field in the
1554 <file>.changes</file> file. See <ref id="f-Distribution">.
1558 <var>urgency</var> is the value for the <tt>Urgency</tt>
1559 field in the <file>.changes</file> file for the upload
1560 (see <ref id="f-Urgency">). It is not possible to specify
1561 an urgency containing commas; commas are used to separate
1562 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1563 <prgn>dpkg</prgn> changelog format (though there is
1564 currently only one useful <var>keyword</var>,
1565 <tt>urgency</tt>).<footnote>
1566 Recognised urgency values are <tt>low</tt>,
1567 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1568 They have an effect on how quickly a package will be
1569 considered for inclusion into the <tt>testing</tt>
1570 distribution, and give an indication of the importance
1571 of any fixes included in this upload.
1576 The change details may in fact be any series of lines
1577 starting with at least two spaces, but conventionally each
1578 change starts with an asterisk and a separating space and
1579 continuation lines are indented so as to bring them in
1580 line with the start of the text above. Blank lines may be
1581 used here to separate groups of changes, if desired.
1585 If this upload resolves bugs recorded in the Bug Tracking
1586 System (BTS), they may be automatically closed on the
1587 inclusion of this package into the Debian archive by
1588 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1589 in the change details.<footnote>
1590 To be precise, the string should match the following
1591 Perl regular expression:
1593 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1595 Then all of the bug numbers listed will be closed by the
1596 archive maintenance script (<prgn>katie</prgn>), or in
1597 the case of an NMU, marked as fixed.
1599 This information is conveyed via the <tt>Closes</tt> field
1600 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1604 The maintainer name and email address used in the changelog
1605 should be the details of the person uploading <em>this</em>
1606 version. They are <em>not</em> necessarily those of the
1607 usual package maintainer. The information here will be
1608 copied to the <tt>Changed-By</tt> field in the
1609 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1610 and then later used to send an acknowledgement when the
1611 upload has been installed.
1615 The <var>date</var> should be in RFC822 format<footnote>
1616 This is generated by the <prgn>822-date</prgn>
1618 </footnote>; it should include the time zone specified
1619 numerically, with the time zone name or abbreviation
1620 optionally present as a comment in parentheses.
1624 The first "title" line with the package name should start
1625 at the left hand margin; the "trailer" line with the
1626 maintainer and date details should be preceded by exactly
1627 one space. The maintainer details and the date must be
1628 separated by exactly two spaces.
1632 For more information on placement of the changelog files
1633 within binary packages, please see <ref id="changelogs">.
1636 <sect1><heading>Alternative changelog formats</heading>
1639 In non-experimental packages you must use a format for
1640 <file>debian/changelog</file> which is supported by the most
1641 recent released version of <prgn>dpkg</prgn>.
1645 It is possible to use a format different from the standard
1646 one by providing a changelog parser for the format you wish
1647 to use. The parser must have an API compatible with that
1648 expected by <prgn>dpkg-genchanges</prgn> and
1649 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1652 If there is general interest in the new format, you should
1653 contact the <package>dpkg</package> maintainer to have the
1654 parser script for it included in the <prgn>dpkg</prgn>
1655 package. (You will need to agree that the parser and its
1656 man page may be distributed under the GNU GPL, just as the rest
1657 of <prgn>dpkg</prgn> is.)
1664 <heading>Error trapping in makefiles</heading>
1667 When <prgn>make</prgn> invokes a command in a makefile
1668 (including your package's upstream makefiles and
1669 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1670 means that <prgn>sh</prgn>'s usual bad error handling
1671 properties apply: if you include a miniature script as one
1672 of the commands in your makefile you'll find that if you
1673 don't do anything about it then errors are not detected
1674 and <prgn>make</prgn> will blithely continue after
1679 Every time you put more than one shell command (this
1680 includes using a loop) in a makefile command you
1681 must make sure that errors are trapped. For
1682 simple compound commands, such as changing directory and
1683 then running a program, using <tt>&&</tt> rather
1684 than semicolon as a command separator is sufficient. For
1685 more complex commands including most loops and
1686 conditionals you should include a separate <tt>set -e</tt>
1687 command at the start of every makefile command that's
1688 actually one of these miniature shell scripts.
1692 <sect id="timestamps">
1693 <heading>Time Stamps</heading>
1695 Maintainers should preserve the modification times of the
1696 upstream source files in a package, as far as is reasonably
1698 The rationale is that there is some information conveyed
1699 by knowing the age of the file, for example, you could
1700 recognize that some documentation is very old by looking
1701 at the modification time, so it would be nice if the
1702 modification time of the upstream source would be
1708 <sect id="restrictions">
1709 <heading>Restrictions on objects in source packages</heading>
1712 The source package may not contain any hard links<footnote>
1714 This is not currently detected when building source
1715 packages, but only when extracting
1719 Hard links may be permitted at some point in the
1720 future, but would require a fair amount of
1723 </footnote>, device special files, sockets or setuid or
1724 setgid files.<footnote>
1725 Setgid directories are allowed.
1730 <sect id="debianrules">
1731 <heading>Main building script: <file>debian/rules</file></heading>
1734 This file must be an executable makefile, and contains the
1735 package-specific recipes for compiling the package and
1736 building binary package(s) from the source.
1740 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1741 so that it can be invoked by saying its name rather than
1742 invoking <prgn>make</prgn> explicitly.
1746 Since an interactive <file>debian/rules</file> script makes it
1747 impossible to auto-compile that package and also makes it
1748 hard for other people to reproduce the same binary
1749 package, all <em>required targets</em> MUST be
1750 non-interactive. At a minimum, required targets are the
1751 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1752 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1753 <em>binary-indep</em>, and <em>build</em>. It also follows
1754 that any target that these targets depend on must also be
1759 The targets are as follows (required unless stated otherwise):
1761 <tag><tt>build</tt></tag>
1764 The <tt>build</tt> target should perform all the
1765 configuration and compilation of the package.
1766 If a package has an interactive pre-build
1767 configuration routine, the Debianized source package
1768 must either be built after this has taken place (so
1769 that the binary package can be built without rerunning
1770 the configuration) or the configuration routine
1771 modified to become non-interactive. (The latter is
1772 preferable if there are architecture-specific features
1773 detected by the configuration routine.)
1777 For some packages, notably ones where the same
1778 source tree is compiled in different ways to produce
1779 two binary packages, the <tt>build</tt> target
1780 does not make much sense. For these packages it is
1781 good enough to provide two (or more) targets
1782 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1783 for each of the ways of building the package, and a
1784 <tt>build</tt> target that does nothing. The
1785 <tt>binary</tt> target will have to build the
1786 package in each of the possible ways and make the
1787 binary package out of each.
1791 The <tt>build</tt> target must not do anything
1792 that might require root privilege.
1796 The <tt>build</tt> target may need to run the
1797 <tt>clean</tt> target first - see below.
1801 When a package has a configuration and build routine
1802 which takes a long time, or when the makefiles are
1803 poorly designed, or when <tt>build</tt> needs to
1804 run <tt>clean</tt> first, it is a good idea to
1805 <tt>touch build</tt> when the build process is
1806 complete. This will ensure that if <tt>debian/rules
1807 build</tt> is run again it will not rebuild the whole
1809 Another common way to do this is for <tt>build</tt>
1810 to depend on <prgn>build-stamp</prgn> and to do
1811 nothing else, and for the <prgn>build-stamp</prgn>
1812 target to do the building and to <tt>touch
1813 build-stamp</tt> on completion. This is
1814 especially useful if the build routine creates a
1815 file or directory called <tt>build</tt>; in such a
1816 case, <tt>build</tt> will need to be listed as
1817 a phony target (i.e., as a dependency of the
1818 <tt>.PHONY</tt> target). See the documentation of
1819 <prgn>make</prgn> for more information on phony
1825 <tag><tt>build-arch</tt> (optional),
1826 <tt>build-indep</tt> (optional)
1830 A package may also provide both of the targets
1831 <tt>build-arch</tt> and <tt>build-indep</tt>.
1832 The <tt>build-arch</tt> target, if provided, should
1833 perform all the configuration and compilation required
1834 for producing all architecture-dependant binary packages
1835 (those packages for which the body of the
1836 <tt>Architecture</tt> field in <tt>debian/control</tt>
1837 is not <tt>all</tt>).
1838 Similarly, the <tt>build-indep</tt> target, if
1839 provided, should perform all the configuration and
1840 compilation required for producing all
1841 architecture-independent binary packages
1842 (those packages for which the body of the
1843 <tt>Architecture</tt> field in <tt>debian/control</tt>
1845 The <tt>build</tt> target should depend on those of the
1846 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1847 are provided in the rules file.
1851 If one or both of the targets <tt>build-arch</tt> and
1852 <tt>build-indep</tt> are not provided, then invoking
1853 <file>debian/rules</file> with one of the not-provided
1854 targets as arguments should produce a exit status code
1855 of 2. Usually this is provided automatically by make
1856 if the target is missing.
1860 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1861 must not do anything that might require root privilege.
1865 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1866 <tt>binary-indep</tt>
1870 The <tt>binary</tt> target must be all that is
1871 necessary for the user to build the binary package(s)
1872 produced from this source package. It is
1873 split into two parts: <prgn>binary-arch</prgn> builds
1874 the binary packages which are specific to a particular
1875 architecture, and <tt>binary-indep</tt> builds
1876 those which are not.
1879 <tt>binary</tt> may be (and commonly is) a target with
1880 no commands which simply depends on
1881 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1884 Both <tt>binary-*</tt> targets should depend on the
1885 <tt>build</tt> target, or on the appropriate
1886 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1887 provided, so that the package is built if it has not
1888 been already. It should then create the relevant
1889 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1890 make their control files and <prgn>dpkg-deb</prgn> to
1891 build them and place them in the parent of the top
1896 Both the <tt>binary-arch</tt> and
1897 <tt>binary-indep</tt> targets <em>must</em> exist.
1898 If one of them has nothing to do (which will always be
1899 the case if the source generates only a single binary
1900 package, whether architecture-dependent or not), it
1901 must still exist and must always succeed.
1905 The <tt>binary</tt> targets must be invoked as
1907 The <prgn>fakeroot</prgn> package often allows one
1908 to build a package correctly even without being
1914 <tag><tt>clean</tt></tag>
1917 This must undo any effects that the <tt>build</tt>
1918 and <tt>binary</tt> targets may have had, except
1919 that it should leave alone any output files created in
1920 the parent directory by a run of a <tt>binary</tt>
1925 If a <tt>build</tt> file is touched at the end of
1926 the <tt>build</tt> target, as suggested above, it
1927 should be removed as the first action that
1928 <tt>clean</tt> performs, so that running
1929 <tt>build</tt> again after an interrupted
1930 <tt>clean</tt> doesn't think that everything is
1935 The <tt>clean</tt> target may need to be
1936 invoked as root if <tt>binary</tt> has been
1937 invoked since the last <tt>clean</tt>, or if
1938 <tt>build</tt> has been invoked as root (since
1939 <tt>build</tt> may create directories, for
1944 <tag><tt>get-orig-source</tt> (optional)</tag>
1947 This target fetches the most recent version of the
1948 original source package from a canonical archive site
1949 (via FTP or WWW, for example), does any necessary
1950 rearrangement to turn it into the original source
1951 tar file format described below, and leaves it in the
1956 This target may be invoked in any directory, and
1957 should take care to clean up any temporary files it
1962 This target is optional, but providing it if
1963 possible is a good idea.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1997 specification string)
2000 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2001 <tt>DEB_*_GNU_TYPE</tt>)
2004 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2005 <tt>DEB_*_GNU_TYPE</tt>)
2007 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2008 the build machine or <tt>HOST</tt> for specification of the
2013 Backward compatibility can be provided in the rules file
2014 by setting the needed variables to suitable default
2015 values; please refer to the documentation of
2016 <prgn>dpkg-architecture</prgn> for details.
2020 It is important to understand that the <tt>DEB_*_ARCH</tt>
2021 string only determines which Debian architecture we are
2022 building on or for. It should not be used to get the CPU
2023 or system information; the GNU style variables should be
2028 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2029 <sect id="substvars">
2030 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2033 When <prgn>dpkg-gencontrol</prgn>,
2034 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2035 generate control files they perform variable substitutions
2036 on their output just before writing it. Variable
2037 substitutions have the form <tt>${<var>variable</var>}</tt>.
2038 The optional file <file>debian/substvars</file> contains
2039 variable substitutions to be used; variables can also be set
2040 directly from <file>debian/rules</file> using the <tt>-V</tt>
2041 option to the source packaging commands, and certain
2042 predefined variables are also available.
2046 The <file>debian/substvars</file> file is usually generated and
2047 modified dynamically by <file>debian/rules</file> targets, in
2048 which case it must be removed by the <tt>clean</tt> target.
2052 See <manref name="dpkg-source" section="1"> for full
2053 details about source variable substitutions, including the
2054 format of <file>debian/substvars</file>.</p>
2057 <sect id="debianfiles">
2058 <heading>Generated files list: <file>debian/files</file></heading>
2061 This file is not a permanent part of the source tree; it
2062 is used while building packages to record which files are
2063 being generated. <prgn>dpkg-genchanges</prgn> uses it
2064 when it generates a <file>.changes</file> file.
2068 It should not exist in a shipped source package, and so it
2069 (and any backup files or temporary files such as
2070 <file>files.new</file><footnote>
2071 <file>files.new</file> is used as a temporary file by
2072 <prgn>dpkg-gencontrol</prgn> and
2073 <prgn>dpkg-distaddfile</prgn> - they write a new
2074 version of <tt>files</tt> here before renaming it,
2075 to avoid leaving a corrupted copy if an error
2077 </footnote>) should be removed by the
2078 <tt>clean</tt> target. It may also be wise to
2079 ensure a fresh start by emptying or removing it at the
2080 start of the <tt>binary</tt> target.
2084 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2085 package, it adds an entry to <file>debian/files</file> for the
2086 <file>.deb</file> file that will be created when <tt>dpkg-deb
2087 --build</tt> is run for that binary package. So for most
2088 packages all that needs to be done with this file is to
2089 delete it in the <tt>clean</tt> target.
2093 If a package upload includes files besides the source
2094 package and any binary packages whose control files were
2095 made with <prgn>dpkg-gencontrol</prgn> then they should be
2096 placed in the parent of the package's top-level directory
2097 and <prgn>dpkg-distaddfile</prgn> should be called to add
2098 the file to the list in <file>debian/files</file>.</p>
2104 <chapt id="controlfields">
2105 <heading>Control files and their fields</heading>
2108 The package management system manipulates data represented in
2109 a common format, known as <em>control data</em>, stored in
2110 <em>control files</em>.
2111 Control files are used for source packages, binary packages and
2112 the <file>.changes</file> files which control the installation
2113 of uploaded files<footnote>
2114 <prgn>dpkg</prgn>'s internal databases are in a similar
2119 <sect id="controlsyntax">
2120 <heading>Syntax of control files</heading>
2123 A control file consists of one or more paragraphs of
2125 The paragraphs are also sometimes referred to as stanzas.
2127 The paragraphs are separated by blank lines. Some control
2128 files allow only one paragraph; others allow several, in
2129 which case each paragraph usually refers to a different
2130 package. (For example, in source packages, the first
2131 paragraph refers to the source package, and later paragraphs
2132 refer to binary packages generated from the source.)
2136 Each paragraph consists of a series of data fields; each
2137 field consists of the field name, followed by a colon and
2138 then the data/value associated with that field. It ends at
2139 the end of the line. Horizontal whitespace (spaces and
2140 tabs) may occur immediately before or after the value and is
2141 ignored there; it is conventional to put a single space
2142 after the colon. For example, a field might be:
2143 <example compact="compact">
2146 the field name is <tt>Package</tt> and the field value
2151 Some fields' values may span several lines; in this case
2152 each continuation line must start with a space or a tab.
2153 Any trailing spaces or tabs at the end of individual
2154 lines of a field value are ignored.
2158 Except where otherwise stated, only a single line of data is
2159 allowed and whitespace is not significant in a field body.
2160 Whitespace must not appear inside names (of packages,
2161 architectures, files or anything else) or version numbers,
2162 or between the characters of multi-character version
2167 Field names are not case-sensitive, but it is usual to
2168 capitalize the field names using mixed case as shown below.
2172 Blank lines, or lines consisting only of spaces and tabs,
2173 are not allowed within field values or between fields - that
2174 would mean a new paragraph.
2179 <sect id="sourcecontrolfiles">
2180 <heading>Source package control files -- <file>debian/control</file></heading>
2183 The <file>debian/control</file> file contains the most vital
2184 (and version-independent) information about the source package
2185 and about the binary packages it creates.
2189 The first paragraph of the control file contains information about
2190 the source package in general. The subsequent sets each describe a
2191 binary package that the source tree builds.
2195 The fields in the general paragraph (the first one, for the source
2198 <list compact="compact">
2199 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2200 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2201 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2202 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2203 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2204 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2205 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2210 The fields in the binary package paragraphs are:
2212 <list compact="compact">
2213 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2214 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2215 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2216 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2217 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2218 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2219 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2224 The syntax and semantics of the fields are described below.
2230 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2231 generate control files for binary packages (see below), by
2232 <prgn>dpkg-genchanges</prgn> to generate the
2233 <tt>.changes</tt> file to accompany the upload, and by
2234 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2235 source control file as part of a source archive.
2239 The fields here may contain variable references - their
2240 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2241 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2242 when they generate output control files.
2243 See <ref id="substvars"> for details.
2248 <sect id="binarycontrolfiles">
2249 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2252 The <file>DEBIAN/control</file> file contains the most vital
2253 (and version-dependent) information about a binary package.
2257 The fields in this file are:
2259 <list compact="compact">
2260 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2261 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2262 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2263 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2264 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2265 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2266 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2267 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2268 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2269 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2275 <sect id="debiansourcecontrolfiles">
2276 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2279 This file contains a series of fields, identified and
2280 separated just like the fields in the control file of
2281 a binary package. The fields are listed below; their
2282 syntax is described above, in <ref id="pkg-controlfields">.
2284 <list compact="compact">
2285 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2286 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2287 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2288 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2289 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2290 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2291 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2292 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2293 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2294 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2299 The source package control file is generated by
2300 <prgn>dpkg-source</prgn> when it builds the source
2301 archive, from other files in the source package,
2302 described above. When unpacking, it is checked against
2303 the files and directories in the other parts of the
2309 <sect id="debianchangesfiles">
2310 <heading>Debian changes files -- <file>.changes</file></heading>
2313 The .changes files are used by the Debian archive maintenance
2314 software to process updates to packages. They contain one
2315 paragraph which contains information from the
2316 <tt>debian/control</tt> file and other data about the
2317 source package gathered via <tt>debian/changelog</tt>
2318 and <tt>debian/rules</tt>.
2322 The fields in this file are:
2324 <list compact="compact">
2325 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2326 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2327 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2328 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2329 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2330 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2333 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2335 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2337 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2343 <sect id="controlfieldslist">
2344 <heading>List of fields</heading>
2346 <sect1 id="f-Source">
2347 <heading><tt>Source</tt></heading>
2350 This field identifies the source package name.
2354 In a main source control information, a <file>.changes</file>
2355 or a <file>.dsc</file> file this may contain only the name
2356 of the source package.
2360 In the control file of a binary package it may be followed
2361 by a version number in parentheses<footnote>
2362 It is customary to leave a space after the package name
2363 if a version number is specified.
2365 This version number may be omitted (and is, by
2366 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2367 the <tt>Version</tt> field of the binary package in
2368 question. The field itself may be omitted from a binary
2369 package control file when the source package has the same
2370 name and version as the binary package.
2374 <sect1 id="f-Maintainer">
2375 <heading><tt>Maintainer</tt></heading>
2378 The package maintainer's name and email address. The name
2379 should come first, then the email address inside angle
2380 brackets <tt><></tt> (in RFC822 format).
2384 If the maintainer's name contains a full stop then the
2385 whole field will not work directly as an email address due
2386 to a misfeature in the syntax specified in RFC822; a
2387 program using this field as an address must check for this
2388 and correct the problem if necessary (for example by
2389 putting the name in round brackets and moving it to the
2390 end, and bringing the email address forward).
2394 <sect1 id="f-Uploaders">
2395 <heading><tt>Uploaders</tt></heading>
2398 List of the names and email addresses of
2399 co-maintaintainers of the package, if any. If the package
2400 has other maintainers beside the one named in the <qref
2401 id="f-Maintainer">Maintainer field</qref>, they their
2402 names and email addresses should be listed here. The
2403 format is the same as that of the Maintainer tag, and
2404 multiple entries should be comma separated. This is an
2409 <sect1 id="f-Changed-By">
2410 <heading><tt>Changed-By</tt></heading>
2413 The name and email address of the person who changed the
2414 said package. Usually the name of the maintainer.
2415 All the rules for the Maintainer field apply here, too.
2419 <sect1 id="f-Section">
2420 <heading><tt>Section</tt></heading>
2423 This field specifies an application area into which the package
2424 has been classified. See <ref id="subsections">.
2428 When it appears in the <file>debian/control</file> file,
2429 it gives the value for the subfield of the same name in
2430 the <tt>Files</tt> field of the <file>.changes</file> file.
2431 It also gives the default for the same field in the binary
2436 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2437 field in the control file of a binary package - use the
2438 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2442 <sect1 id="f-Priority">
2443 <heading><tt>Priority</tt></heading>
2446 This field represents how important that it is that the user
2447 have the package installed. See <ref id="priorities">.
2451 When it appears in the <file>debian/control</file> file,
2452 it gives the value for the subfield of the same name in
2453 the <tt>Files</tt> field of the <file>.changes</file> file.
2454 It also gives the default for the same field in the binary
2459 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2460 field in the control file of a binary package - use the
2461 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2465 <sect1 id="f-Package">
2466 <heading><tt>Package</tt></heading>
2469 The name of the binary package.
2473 Package names must consist only of lower case letters
2474 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2475 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2476 They must be at least two characters long and must start
2477 with an alphanumeric character.
2481 <sect1 id="f-Architecture">
2482 <heading><tt>Architecture</tt></heading>
2485 Depending on context and the control file used, the
2486 <tt>Architecture</tt> field can include the following sets of
2489 <item>A unique single word identifying a Debian machine
2490 architecture, see <ref id="arch-spec">.
2491 <item><tt>all</tt>, which indicates an
2492 architecture-independent package.
2493 <item><tt>any</tt>, which indicates a package available
2494 for building on any architecture.
2495 <item><tt>source</tt>, which indicates a source package.
2500 In the main <file>debian/control</file> file in the source
2501 package, or in the source package control file
2502 <file>.dsc</file>, one may specify a list of architectures
2503 separated by spaces, or the special values <tt>any</tt> or
2508 Specifying <tt>any</tt> indicates that the source package
2509 isn't dependent on any particular architecture and should
2510 compile fine on any one. The produced binary package(s)
2511 will be specific to whatever the current build architecture
2513 This is the most often used setting, and is recommended
2514 for new packages that aren't <tt>Architecture: all</tt>.
2519 Specifying a list of architectures indicates that the source
2520 will build an architecture-dependent package, and will only
2521 work correctly on the listed architectures.<footnote>
2522 This is a setting used for a minority of cases where the
2523 program is not portable. Generally, it should not be used
2529 In a <file>.changes</file> file, the <tt>Architecture</tt>
2530 field lists the architecture(s) of the package(s)
2531 currently being uploaded. This will be a list; if the
2532 source for the package is also being uploaded, the special
2533 entry <tt>source</tt> is also present.
2537 See <ref id="debianrules"> for information how to get the
2538 architecture for the build process.
2542 <sect1 id="f-Essential">
2543 <heading><tt>Essential</tt></heading>
2546 This is a boolean field which may occur only in the
2547 control file of a binary package or in a per-package fields
2548 paragraph of a main source control data file.
2552 If set to <tt>yes</tt> then the package management system
2553 will refuse to remove the package (upgrading and replacing
2554 it is still possible). The other possible value is <tt>no</tt>,
2555 which is the same as not having the field at all.
2560 <heading>Package interrelationship fields:
2561 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2562 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2563 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2567 These fields describe the package's relationships with
2568 other packages. Their syntax and semantics are described
2569 in <ref id="relationships">.</p>
2572 <sect1 id="f-Standards-Version">
2573 <heading><tt>Standards-Version</tt></heading>
2576 The most recent version of the standards (the policy
2577 manual and associated texts) with which the package
2582 The version number has four components: major and minor
2583 version number and major and minor patch level. When the
2584 standards change in a way that requires every package to
2585 change the major number will be changed. Significant
2586 changes that will require work in many packages will be
2587 signaled by a change to the minor number. The major patch
2588 level will be changed for any change to the meaning of the
2589 standards, however small; the minor patch level will be
2590 changed when only cosmetic, typographical or other edits
2591 are made which neither change the meaning of the document
2592 nor affect the contents of packages.
2596 Thus only the first three components of the policy version
2597 are significant in the <em>Standards-Version</em> control
2598 field, and so either these three components or the all
2599 four components may be specified.<footnote>
2600 In the past, people specified the full version number
2601 in the Standards-Version field, for example "2.3.0.0".
2602 Since minor patch-level changes don't introduce new
2603 policy, it was thought it would be better to relax
2604 policy and only require the first 3 components to be
2605 specified, in this example "2.3.0". All four
2606 components may still be used if someone wishes to do so.
2612 <sect1 id="f-Version">
2613 <heading><tt>Version</tt></heading>
2616 The version number of a package. The format is:
2617 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2621 The three components here are:
2623 <tag><var>epoch</var></tag>
2626 This is a single (generally small) unsigned integer. It
2627 may be omitted, in which case zero is assumed. If it is
2628 omitted then the <var>upstream_version</var> may not
2633 It is provided to allow mistakes in the version numbers
2634 of older versions of a package, and also a package's
2635 previous version numbering schemes, to be left behind.
2639 <tag><var>upstream_version</var></tag>
2642 This is the main part of the version number. It is
2643 usually the version number of the original ("upstream")
2644 package from which the <file>.deb</file> file has been made,
2645 if this is applicable. Usually this will be in the same
2646 format as that specified by the upstream author(s);
2647 however, it may need to be reformatted to fit into the
2648 package management system's format and comparison
2653 The comparison behavior of the package management system
2654 with respect to the <var>upstream_version</var> is
2655 described below. The <var>upstream_version</var>
2656 portion of the version number is mandatory.
2660 The <var>upstream_version</var> may contain only
2661 alphanumerics<footnote>
2662 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2664 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2665 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2666 start with a digit. If there is no
2667 <var>debian_revision</var> then hyphens are not allowed;
2668 if there is no <var>epoch</var> then colons are not
2673 <tag><var>debian_revision</var></tag>
2676 This part of the version number specifies the version of
2677 the Debian package based on the upstream version. It
2678 may contain only alphanumerics and the characters
2679 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2680 compared in the same way as the
2681 <var>upstream_version</var> is.
2685 It is optional; if it isn't present then the
2686 <var>upstream_version</var> may not contain a hyphen.
2687 This format represents the case where a piece of
2688 software was written specifically to be turned into a
2689 Debian package, and so there is only one "debianization"
2690 of it and therefore no revision indication is required.
2694 It is conventional to restart the
2695 <var>debian_revision</var> at <tt>1</tt> each time the
2696 <var>upstream_version</var> is increased.
2700 The package management system will break the version
2701 number apart at the last hyphen in the string (if there
2702 is one) to determine the <var>upstream_version</var> and
2703 <var>debian_revision</var>. The absence of a
2704 <var>debian_revision</var> compares earlier than the
2705 presence of one (but note that the
2706 <var>debian_revision</var> is the least significant part
2707 of the version number).
2714 The <var>upstream_version</var> and <var>debian_revision</var>
2715 parts are compared by the package management system using the
2720 The strings are compared from left to right.
2724 First the initial part of each string consisting entirely of
2725 non-digit characters is determined. These two parts (one of
2726 which may be empty) are compared lexically. If a difference
2727 is found it is returned. The lexical comparison is a
2728 comparison of ASCII values modified so that all the letters
2729 sort earlier than all the non-letters.
2733 Then the initial part of the remainder of each string which
2734 consists entirely of digit characters is determined. The
2735 numerical values of these two parts are compared, and any
2736 difference found is returned as the result of the comparison.
2737 For these purposes an empty string (which can only occur at
2738 the end of one or both version strings being compared) counts
2743 These two steps (comparing and removing initial non-digit
2744 strings and initial digit strings) are repeated until a
2745 difference is found or both strings are exhausted.
2749 Note that the purpose of epochs is to allow us to leave behind
2750 mistakes in version numbering, and to cope with situations
2751 where the version numbering scheme changes. It is
2752 <em>not</em> intended to cope with version numbers containing
2753 strings of letters which the package management system cannot
2754 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2755 silly orderings (the author of this manual has heard of a
2756 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2757 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2758 <tt>2</tt> and so forth).
2762 <sect1 id="f-Description">
2763 <heading><tt>Description</tt></heading>
2766 In a source or binary control file, the <tt>Description</tt>
2767 field contains a description of the binary package, consisting
2768 of two parts, the synopsis or the short description, and the
2769 long description. The field's format is as follows:
2774 Description: <single line synopsis>
2775 <extended description over several lines>
2780 The lines in the extended description can have these formats:
2786 Those starting with a single space are part of a paragraph.
2787 Successive lines of this form will be word-wrapped when
2788 displayed. The leading space will usually be stripped off.
2792 Those starting with two or more spaces. These will be
2793 displayed verbatim. If the display cannot be panned
2794 horizontally, the displaying program will linewrap them "hard"
2795 (i.e., without taking account of word breaks). If it can they
2796 will be allowed to trail off to the right. None, one or two
2797 initial spaces may be deleted, but the number of spaces
2798 deleted from each line will be the same (so that you can have
2799 indenting work correctly, for example).
2803 Those containing a single space followed by a single full stop
2804 character. These are rendered as blank lines. This is the
2805 <em>only</em> way to get a blank line<footnote>
2806 Completely empty lines will not be rendered as blank lines.
2807 Instead, they will cause the parser to think you're starting
2808 a whole new record in the control file, and will therefore
2809 likely abort with an error.
2814 Those containing a space, a full stop and some more characters.
2815 These are for future expansion. Do not use them.
2821 Do not use tab characters. Their effect is not predictable.
2825 See <ref id="descriptions"> for further information on this.
2829 In a <file>.changes</file> file, the <tt>Description</tt> field
2830 contains a summary of the descriptions for the packages being
2835 The part of the field before the first newline is empty;
2836 thereafter each line has the name of a binary package and
2837 the summary description line from that binary package.
2838 Each line is indented by one space.
2843 <sect1 id="f-Distribution">
2844 <heading><tt>Distribution</tt></heading>
2847 In a <file>.changes</file> file or parsed changelog output
2848 this contains the (space-separated) name(s) of the
2849 distribution(s) where this version of the package should
2850 be installed. Valid distributions are determined by the
2851 archive maintainers.<footnote>
2852 Current distribution names are:
2853 <taglist compact="compact">
2854 <tag><em>stable</em></tag>
2856 This is the current "released" version of Debian
2857 GNU/Linux. Once the distribution is
2858 <em>stable</em> only security fixes and other
2859 major bug fixes are allowed. When changes are
2860 made to this distribution, the release number is
2861 increased (for example: 2.2r1 becomes 2.2r2 then
2865 <tag><em>unstable</em></tag>
2867 This distribution value refers to the
2868 <em>developmental</em> part of the Debian
2869 distribution tree. New packages, new upstream
2870 versions of packages and bug fixes go into the
2871 <em>unstable</em> directory tree. Download from
2872 this distribution at your own risk.
2875 <tag><em>testing</em></tag>
2877 This distribution value refers to the
2878 <em>testing</em> part of the Debian distribution
2879 tree. It receives its packages from the
2880 unstable distribution after a short time lag to
2881 ensure that there are no major issues with the
2882 unstable packages. It is less prone to breakage
2883 than unstable, but still risky. It is not
2884 possible to upload packages directly to
2888 <tag><em>frozen</em></tag>
2890 From time to time, the <em>testing</em>
2891 distribution enters a state of "code-freeze" in
2892 anticipation of release as a <em>stable</em>
2893 version. During this period of testing only
2894 fixes for existing or newly-discovered bugs will
2895 be allowed. The exact details of this stage are
2896 determined by the Release Manager.
2899 <tag><em>experimental</em></tag>
2901 The packages with this distribution value are
2902 deemed by their maintainers to be high
2903 risk. Oftentimes they represent early beta or
2904 developmental packages from various sources that
2905 the maintainers want people to try, but are not
2906 ready to be a part of the other parts of the
2907 Debian distribution tree. Download at your own
2913 You should list <em>all</em> distributions that the
2914 package should be installed into.
2918 More information is available in the Debian Developer's
2919 Reference, section "The Debian archive".
2926 <heading><tt>Date</tt></heading>
2929 This field includes the date the package was built or last edited.
2933 The value of this field is usually extracted from the
2934 <file>debian/changelog</file> file - see
2935 <ref id="dpkgchangelog">).
2939 <sect1 id="f-Format">
2940 <heading><tt>Format</tt></heading>
2943 This field specifies a format revision for the file.
2944 The most current format described in the Policy Manual
2945 is version <strong>1.5</strong>. The syntax of the
2946 format value is the same as that of a package version
2947 number except that no epoch or Debian revision is allowed
2948 - see <ref id="f-Version">.
2952 <sect1 id="f-Urgency">
2953 <heading><tt>Urgency</tt></heading>
2956 This is a description of how important it is to upgrade to
2957 this version from previous ones. It consists of a single
2958 keyword usually taking one of the values <tt>low</tt>,
2959 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2960 followed by an optional commentary (separated by a space)
2961 which is usually in parentheses. For example:
2964 Urgency: low (HIGH for users of diversions)
2970 The value of this field is usually extracted from the
2971 <file>debian/changelog</file> file - see
2972 <ref id="dpkgchangelog">.
2976 <sect1 id="f-Changes">
2977 <heading><tt>Changes</tt></heading>
2980 This field contains the human-readable changes data, describing
2981 the differences between the last version and the current one.
2985 There should be nothing in this field before the first
2986 newline; all the subsequent lines must be indented by at
2987 least one space; blank lines must be represented by a line
2988 consiting only of a space and a full stop.
2992 The value of this field is usually extracted from the
2993 <file>debian/changelog</file> file - see
2994 <ref id="dpkgchangelog">).
2998 Each version's change information should be preceded by a
2999 "title" line giving at least the version, distribution(s)
3000 and urgency, in a human-readable way.
3004 If data from several versions is being returned the entry
3005 for the most recent version should be returned first, and
3006 entries should be separated by the representation of a
3007 blank line (the "title" line may also be followed by the
3008 representation of blank line).
3012 <sect1 id="f-Binary">
3013 <heading><tt>Binary</tt></heading>
3016 This field is a list of binary packages.
3020 When it appears in the <file>.dsc</file> file it is the list
3021 of binary packages which a source package can produce. It
3022 does not necessarily produce all of these binary packages
3023 for every architecture. The source control file doesn't
3024 contain details of which architectures are appropriate for
3025 which of the binary packages.
3029 When it appears in a <file>.changes</file> file it lists the
3030 names of the binary packages actually being uploaded.
3034 The syntax is a list of binary packages separated by
3036 A space after each comma is conventional.
3037 </footnote>. Currently the packages must be separated using
3038 only spaces in the <file>.changes</file> file.
3042 <sect1 id="f-Installed-Size">
3043 <heading><tt>Installed-Size</tt></heading>
3046 This field appears in the control files of binary
3047 packages, and in the <file>Packages</file> files. It gives
3048 the total amount of disk space required to install the
3053 The disk space is represented in kilobytes as a simple
3058 <sect1 id="f-Files">
3059 <heading><tt>Files</tt></heading>
3062 This field contains a list of files with information about
3063 each one. The exact information and syntax varies with
3064 the context. In all cases the part of the field
3065 contents on the same line as the field name is empty. The
3066 remainder of the field is one line per file, each line
3067 being indented by one space and containing a number of
3068 sub-fields separated by spaces.
3072 In the <file>.dsc</file> file, each line contains the MD5
3073 checksum, size and filename of the tar file and (if applicable)
3074 diff file which make up the remainder of the source
3076 That is, the parts which are not the <tt>.dsc</tt>.
3078 The exact forms of the filenames are described
3079 in <ref id="pkg-sourcearchives">.
3083 In the <file>.changes</file> file this contains one line per
3084 file being uploaded. Each line contains the MD5 checksum,
3085 size, section and priority and the filename.
3086 The <qref id="f-Section">section</qref>
3087 and <qref id="f-Priority">priority</qref>
3088 are the values of the corresponding fields in
3089 the main source control file. If no section or priority is
3090 specified then <tt>-</tt> should be used, though section
3091 and priority values must be specified for new packages to
3092 be installed properly.
3096 The special value <tt>byhand</tt> for the section in a
3097 <tt>.changes</tt> file indicates that the file in question
3098 is not an ordinary package file and must by installed by
3099 hand by the distribution maintainers. If the section is
3100 <tt>byhand</tt> the priority should be <tt>-</tt>.
3104 If a new Debian revision of a package is being shipped and
3105 no new original source archive is being distributed the
3106 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3107 entry for the original source archive
3108 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3109 but the <file>.changes</file> file should leave it out. In
3110 this case the original source archive on the distribution
3111 site must match exactly, byte-for-byte, the original
3112 source archive which was used to generate the
3113 <file>.dsc</file> file and diff which are being uploaded.</p>
3116 <sect1 id="f-Closes">
3117 <heading><tt>Closes</tt></heading>
3120 A space-separated list of bug report numbers that the upload
3121 governed by the .changes file closes.
3128 <heading>User-defined fields</heading>
3131 Additional user-defined fields may be added to the
3132 source package control file. Such fields will be
3133 ignored, and not copied to (for example) binary or
3134 source package control files or upload control files.
3138 If you wish to add additional unsupported fields to
3139 these output files you should use the mechanism
3144 Fields in the main source control information file with
3145 names starting <tt>X</tt>, followed by one or more of
3146 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3147 be copied to the output files. Only the part of the
3148 field name after the hyphen will be used in the output
3149 file. Where the letter <tt>B</tt> is used the field
3150 will appear in binary package control files, where the
3151 letter <tt>S</tt> is used in source package control
3152 files and where <tt>C</tt> is used in upload control
3153 (<tt>.changes</tt>) files.
3157 For example, if the main source information control file
3160 XBS-Comment: I stand between the candle and the star.
3162 then the binary and source package control files will contain the
3165 Comment: I stand between the candle and the star.
3174 <chapt id="maintainerscripts">
3175 <heading>Package maintainer scripts and installation procedure</heading>
3178 <heading>Introduction to package maintainer scripts</heading>
3181 It is possible to supply scripts as part of a package which
3182 the package management system will run for you when your
3183 package is installed, upgraded or removed.
3187 These scripts are the files <prgn>preinst</prgn>,
3188 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3189 control area of the package. They must be proper executable
3190 files; if they are scripts (which is recommended), they must
3191 start with the usual <tt>#!</tt> convention. They should be
3192 readable and executable by anyone, and not world-writable.
3196 The package management system looks at the exit status from
3197 these scripts. It is important that they exit with a
3198 non-zero status if there is an error, so that the package
3199 management system can stop its processing. For shell
3200 scripts this means that you <em>almost always</em> need to
3201 use <tt>set -e</tt> (this is usually true when writing shell
3202 scripts, in fact). It is also important, of course, that
3203 they don't exit with a non-zero status if everything went
3208 When a package is upgraded a combination of the scripts from
3209 the old and new packages is called during the upgrade
3210 procedure. If your scripts are going to be at all
3211 complicated you need to be aware of this, and may need to
3212 check the arguments to your scripts.
3216 Broadly speaking the <prgn>preinst</prgn> is called before
3217 (a particular version of) a package is installed, and the
3218 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3219 before (a version of) a package is removed and the
3220 <prgn>postrm</prgn> afterwards.
3224 Programs called from maintainer scripts should not normally
3225 have a path prepended to them. Before installation is
3226 started, the package management system checks to see if the
3227 programs <prgn>ldconfig</prgn>,
3228 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3229 and <prgn>update-rc.d</prgn> can be found via the
3230 <tt>PATH</tt> environment variable. Those programs, and any
3231 other program that one would expect to be on the
3232 <tt>PATH</tt>, should thus be invoked without an absolute
3233 pathname. Maintainer scripts should also not reset the
3234 <tt>PATH</tt>, though they might choose to modify it by
3235 prepending or appending package-specific directories. These
3236 considerations really apply to all shell scripts.</p>
3239 <sect id="idempotency">
3240 <heading>Maintainer scripts Idempotency</heading>
3243 It is necessary for the error recovery procedures that the
3244 scripts be idempotent. This means that if it is run
3245 successfully, and then it is called again, it doesn't bomb
3246 out or cause any harm, but just ensures that everything is
3247 the way it ought to be. If the first call failed, or
3248 aborted half way through for some reason, the second call
3249 should merely do the things that were left undone the first
3250 time, if any, and exit with a success status if everything
3252 This is so that if an error occurs, the user interrupts
3253 <prgn>dpkg</prgn> or some other unforeseen circumstance
3254 happens you don't leave the user with a badly-broken
3255 package when <prgn>dpkg</prgn> attempts to repeat the
3261 <sect id="controllingterminal">
3262 <heading>Controlling terminal for maintainer scripts</heading>
3265 The maintainer scripts are guaranteed to run with a
3266 controlling terminal and can interact with the user.
3267 If they need to prompt for passwords, do full-screen
3268 interaction or something similar you should do these
3269 things to and from <file>/dev/tty</file>, since
3270 <prgn>dpkg</prgn> will at some point redirect scripts'
3271 standard input and output so that it can log the
3272 installation process. Likewise, because these scripts
3273 may be executed with standard output redirected into a
3274 pipe for logging purposes, Perl scripts should set
3275 unbuffered output by setting <tt>$|=1</tt> so that the
3276 output is printed immediately rather than being
3281 Each script should return a zero exit status for
3282 success, or a nonzero one for failure.
3286 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3291 <list compact="compact">
3293 <var>new-preinst</var> <tt>install</tt>
3296 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3299 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3302 <var>old-preinst</var> <tt>abort-upgrade</tt>
3303 <var>new-version</var>
3308 <list compact="compact">
3310 <var>postinst</var> <tt>configure</tt>
3311 <var>most-recently-configured-version</var>
3314 <var>old-postinst</var> <tt>abort-upgrade</tt>
3315 <var>new-version</var>
3318 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3319 <tt>in-favour</tt> <var>package</var>
3320 <var>new-version</var>
3323 <var>deconfigured's-postinst</var>
3324 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3325 <var>failed-install-package</var> <var>version</var>
3326 <tt>removing</tt> <var>conflicting-package</var>
3332 <list compact="compact">
3334 <var>prerm</var> <tt>remove</tt>
3337 <var>old-prerm</var> <tt>upgrade</tt>
3338 <var>new-version</var>
3341 <var>new-prerm</var> <tt>failed-upgrade</tt>
3342 <var>old-version</var>
3345 <var>conflictor's-prerm</var> <tt>remove</tt>
3346 <tt>in-favour</tt> <var>package</var>
3347 <var>new-version</var>
3350 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3351 <tt>in-favour</tt> <var>package-being-installed</var>
3352 <var>version</var> <tt>removing</tt>
3353 <var>conflicting-package</var>
3359 <list compact="compact">
3361 <var>postrm</var> <tt>remove</tt>
3364 <var>postrm</var> <tt>purge</tt>
3367 <var>old-postrm</var> <tt>upgrade</tt>
3368 <var>new-version</var>
3371 <var>new-postrm</var> <tt>failed-upgrade</tt>
3372 <var>old-version</var>
3375 <var>new-postrm</var> <tt>abort-install</tt>
3378 <var>new-postrm</var> <tt>abort-install</tt>
3379 <var>old-version</var>
3382 <var>new-postrm</var> <tt>abort-upgrade</tt>
3383 <var>old-version</var>
3386 <var>disappearer's-postrm</var> <tt>disappear</tt>
3387 <var>overwriter</var>
3388 <var>overwriter-version</var>
3394 <sect id="unpackphase">
3395 <heading>Details of unpack phase of installation or upgrade</heading>
3398 The procedure on installation/upgrade/overwrite/disappear
3399 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3400 stage of <tt>dpkg --install</tt>) is as follows. In each
3401 case, if a major error occurs (unless listed below) the
3402 actions are, in general, run backwards - this means that the
3403 maintainer scripts are run with different arguments in
3404 reverse order. These are the "error unwind" calls listed
3411 If a version of the package is already installed, call
3412 <example compact="compact">
3413 <var>old-prerm</var> upgrade <var>new-version</var>
3417 If the script runs but exits with a non-zero
3418 exit status, <prgn>dpkg</prgn> will attempt:
3419 <example compact="compact">
3420 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3422 Error unwind, for both the above cases:
3423 <example compact="compact">
3424 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3431 If a "conflicting" package is being removed at the same time:
3434 If any packages depended on that conflicting
3435 package and <tt>--auto-deconfigure</tt> is
3436 specified, call, for each such package:
3437 <example compact="compact">
3438 <var>deconfigured's-prerm</var> deconfigure \
3439 in-favour <var>package-being-installed</var> <var>version</var> \
3440 removing <var>conflicting-package</var> <var>version</var>
3443 <example compact="compact">
3444 <var>deconfigured's-postinst</var> abort-deconfigure \
3445 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3446 removing <var>conflicting-package</var> <var>version</var>
3448 The deconfigured packages are marked as
3449 requiring configuration, so that if
3450 <tt>--install</tt> is used they will be
3451 configured again if possible.
3454 To prepare for removal of the conflicting package, call:
3455 <example compact="compact">
3456 <var>conflictor's-prerm</var> remove \
3457 in-favour <var>package</var> <var>new-version</var>
3460 <example compact="compact">
3461 <var>conflictor's-postinst</var> abort-remove \
3462 in-favour <var>package</var> <var>new-version</var>
3471 If the package is being upgraded, call:
3472 <example compact="compact">
3473 <var>new-preinst</var> upgrade <var>old-version</var>
3477 Otherwise, if the package had some configuration
3478 files from a previous version installed (i.e., it
3479 is in the "configuration files only" state):
3480 <example compact="compact">
3481 <var>new-preinst</var> install <var>old-version</var>
3485 Otherwise (i.e., the package was completely purged):
3486 <example compact="compact">
3487 <var>new-preinst</var> install
3489 Error unwind actions, respectively:
3490 <example compact="compact">
3491 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3492 <var>new-postrm</var> abort-install <var>old-version</var>
3493 <var>new-postrm</var> abort-install
3501 The new package's files are unpacked, overwriting any
3502 that may be on the system already, for example any
3503 from the old version of the same package or from
3504 another package. Backups of the old files are kept
3505 temporarily, and if anything goes wrong the package
3506 management system will attempt to put them back as
3507 part of the error unwind.
3511 It is an error for a package to contain files which
3512 are on the system in another package, unless
3513 <tt>Replaces</tt> is used (see <ref id="replaces">).
3515 The following paragraph is not currently the case:
3516 Currently the <tt>- - force-overwrite</tt> flag is
3517 enabled, downgrading it to a warning, but this may not
3523 It is a more serious error for a package to contain a
3524 plain file or other kind of non-directory where another
3525 package has a directory (again, unless
3526 <tt>Replaces</tt> is used). This error can be
3527 overridden if desired using
3528 <tt>--force-overwrite-dir</tt>, but this is not
3533 Packages which overwrite each other's files produce
3534 behavior which, though deterministic, is hard for the
3535 system administrator to understand. It can easily
3536 lead to "missing" programs if, for example, a package
3537 is installed which overwrites a file from another
3538 package, and is then removed again.<footnote>
3539 Part of the problem is due to what is arguably a
3540 bug in <prgn>dpkg</prgn>.
3545 A directory will never be replaced by a symbolic link
3546 to a directory or vice versa; instead, the existing
3547 state (symlink or not) will be left alone and
3548 <prgn>dpkg</prgn> will follow the symlink if there is
3557 If the package is being upgraded, call
3558 <example compact="compact">
3559 <var>old-postrm</var> upgrade <var>new-version</var>
3563 If this fails, <prgn>dpkg</prgn> will attempt:
3564 <example compact="compact">
3565 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3567 Error unwind, for both cases:
3568 <example compact="compact">
3569 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3576 This is the point of no return - if
3577 <prgn>dpkg</prgn> gets this far, it won't back off
3578 past this point if an error occurs. This will
3579 leave the package in a fairly bad state, which
3580 will require a successful re-installation to clear
3581 up, but it's when <prgn>dpkg</prgn> starts doing
3582 things that are irreversible.
3587 Any files which were in the old version of the package
3588 but not in the new are removed.
3592 The new file list replaces the old.
3596 The new maintainer scripts replace the old.
3600 Any packages all of whose files have been overwritten
3601 during the installation, and which aren't required for
3602 dependencies, are considered to have been removed.
3603 For each such package
3606 <prgn>dpkg</prgn> calls:
3607 <example compact="compact">
3608 <var>disappearer's-postrm</var> disappear \
3609 <var>overwriter</var> <var>overwriter-version</var>
3613 The package's maintainer scripts are removed.
3616 It is noted in the status database as being in a
3617 sane state, namely not installed (any conffiles
3618 it may have are ignored, rather than being
3619 removed by <prgn>dpkg</prgn>). Note that
3620 disappearing packages do not have their prerm
3621 called, because <prgn>dpkg</prgn> doesn't know
3622 in advance that the package is going to
3629 Any files in the package we're unpacking that are also
3630 listed in the file lists of other packages are removed
3631 from those lists. (This will lobotomize the file list
3632 of the "conflicting" package if there is one.)
3636 The backup files made during installation, above, are
3642 The new package's status is now sane, and recorded as
3647 Here is another point of no return - if the
3648 conflicting package's removal fails we do not unwind
3649 the rest of the installation; the conflicting package
3650 is left in a half-removed limbo.
3655 If there was a conflicting package we go and do the
3656 removal actions (described below), starting with the
3657 removal of the conflicting package's files (any that
3658 are also in the package being installed have already
3659 been removed from the conflicting package's file list,
3660 and so do not get removed now).
3666 <sect id="configdetails"><heading>Details of configuration</heading>
3669 When we configure a package (this happens with <tt>dpkg
3670 --install</tt> and <tt>dpkg --configure</tt>), we first
3671 update any <tt>conffile</tt>s and then call:
3672 <example compact="compact">
3673 <var>postinst</var> configure <var>most-recently-configured-version</var>
3678 No attempt is made to unwind after errors during
3683 If there is no most recently configured version
3684 <prgn>dpkg</prgn> will pass a null argument.
3687 Historical note: Truly ancient (pre-1997) versions of
3688 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3689 (including the angle brackets) in this case. Even older
3690 ones did not pass a second argument at all, under any
3691 circumstance. Note that upgrades using such an old dpkg
3692 version are unlikely to work for other reasons, even if
3693 this old argument behavior is handled by your postinst script.
3699 <sect id="removedetails"><heading>Details of removal and/or
3700 configuration purging</heading>
3705 <example compact="compact">
3706 <var>prerm</var> remove
3710 The package's files are removed (except <tt>conffile</tt>s).
3713 <example compact="compact">
3714 <var>postrm</var> remove
3719 All the maintainer scripts except the <prgn>postrm</prgn>
3724 If we aren't purging the package we stop here. Note
3725 that packages which have no <prgn>postrm</prgn> and no
3726 <tt>conffile</tt>s are automatically purged when
3727 removed, as there is no difference except for the
3728 <prgn>dpkg</prgn> status.
3732 The <tt>conffile</tt>s and any backup files
3733 (<tt>~</tt>-files, <tt>#*#</tt> files,
3734 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3738 <example compact="compact">
3739 <var>postrm</var> purge
3743 The package's file list is removed.
3747 If there are problems during this process, we call
3748 <example compact="compact">postinst
3749 abort-remove</example>. No other attempt is made to unwind
3750 after errors during removal.
3756 <chapt id="relationships">
3757 <heading>Declaring relationships between packages</heading>
3759 <sect id="depsyntax">
3760 <heading>Syntax of relationship fields</heading>
3763 These fields all have a uniform syntax. They are a list of
3764 package names separated by commas.
3768 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3769 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3770 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3771 control file fields of the package, which declare
3772 dependencies on other packages, the package names listed may
3773 also include lists of alternative package names, separated
3774 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3775 if any one of the alternative packages is installed, that
3776 part of the dependency is considered to be satisfied.
3780 All of the fields except for <tt>Provides</tt> may restrict
3781 their applicability to particular versions of each named
3782 package. This is done in parentheses after each individual
3783 package name; the parentheses should contain a relation from
3784 the list below followed by a version number, in the format
3785 described in <ref id="f-Version">.
3789 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3790 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3791 strictly earlier, earlier or equal, exactly equal, later or
3792 equal and strictly later, respectively. The deprecated
3793 forms <tt><</tt> and <tt>></tt> were used to mean
3794 earlier/later or equal, rather than strictly earlier/later,
3795 so they should not appear in new packages (though
3796 <prgn>dpkg</prgn> still supports them).
3800 Whitespace may appear at any point in the version
3801 specification subject to the rules in <ref
3802 id="controlsyntax">, and must appear where it's necessary to
3803 disambiguate; it is not otherwise significant. For
3804 consistency and in case of future changes to
3805 <prgn>dpkg</prgn> it is recommended that a single space be
3806 used after a version relationship and before a version
3807 number; it is also conventional to put a single space after
3808 each comma, on either side of each vertical bar, and before
3809 each open parenthesis.
3813 For example, a list of dependencies might appear as:
3814 <example compact="compact">
3817 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3822 All fields that specify build-time relationships
3823 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3824 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3825 may be restricted to a certain set of architectures. This
3826 is indicated in brackets after each individual package name and
3827 the optional version specification. The brackets enclose a
3828 list of Debian architecture names separated by whitespace.
3829 Exclamation marks may be prepended to each of the names.
3830 (It is not permitted for some names to be prepended with
3831 exclamation marks and others not.) If the current Debian
3832 host architecture is not in this list and there are no
3833 exclamation marks in the list, or it is in the list with a
3834 prepended exclamation mark, the package name and the
3835 associated version specification are ignored completely for
3836 the purposes of defining the relationships.
3841 <example compact="compact">
3843 Build-Depends-Indep: texinfo
3844 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3845 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3850 Note that the binary package relationship fields such as
3851 <tt>Depends</tt> appear in one of the binary package
3852 sections of the control file, whereas the build-time
3853 relationships such as <tt>Build-Depends</tt> appear in the
3854 source package section of the control file (which is the
3859 <sect id="binarydeps">
3860 <heading>Binary Dependencies - <tt>Depends</tt>,
3861 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3862 <tt>Pre-Depends</tt>
3866 Packages can declare in their control file that they have
3867 certain relationships to other packages - for example, that
3868 they may not be installed at the same time as certain other
3869 packages, and/or that they depend on the presence of others.
3873 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3874 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3875 <tt>Conflicts</tt> control file fields.
3879 These six fields are used to declare a dependency
3880 relationship by one package on another. Except for
3881 <tt>Enhances</tt>, they appear in the depending (binary)
3882 package's control file. (<tt>Enhances</tt> appears in the
3883 recommending package's control file.)
3887 A <tt>Depends</tt> field takes effect <em>only</em> when a
3888 package is to be configured. It does not prevent a package
3889 being on the system in an unconfigured state while its
3890 dependencies are unsatisfied, and it is possible to replace
3891 a package whose dependencies are satisfied and which is
3892 properly installed with a different version whose
3893 dependencies are not and cannot be satisfied; when this is
3894 done the depending package will be left unconfigured (since
3895 attempts to configure it will give errors) and will not
3896 function properly. If it is necessary, a
3897 <tt>Pre-Depends</tt> field can be used, which has a partial
3898 effect even when a package is being unpacked, as explained
3899 in detail below. (The other three dependency fields,
3900 <tt>Recommends</tt>, <tt>Suggests</tt> and
3901 <tt>Enhances</tt>, are only used by the various front-ends
3902 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3906 For this reason packages in an installation run are usually
3907 all unpacked first and all configured later; this gives
3908 later versions of packages with dependencies on later
3909 versions of other packages the opportunity to have their
3910 dependencies satisfied.
3914 The <tt>Depends</tt> field thus allows package maintainers
3915 to impose an order in which packages should be configured.
3919 The meaning of the five dependency fields is as follows:
3921 <tag><tt>Depends</tt></tag>
3924 This declares an absolute dependency. A package will
3925 not be configured unless all of the packages listed in
3926 its <tt>Depends</tt> field have been correctly
3931 The <tt>Depends</tt> field should be used if the
3932 depended-on package is required for the depending
3933 package to provide a significant amount of
3938 The <tt>Depends</tt> field should also be used if the
3939 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3940 <prgn>postrm</prgn> scripts require the package to be
3941 present in order to run. Note, however, that the
3942 <prgn>postrm</prgn> cannot rely on any non-essential
3943 packages to be present during the <tt>purge</tt>
3947 <tag><tt>Recommends</tt></tag>
3950 This declares a strong, but not absolute, dependency.
3954 The <tt>Recommends</tt> field should list packages
3955 that would be found together with this one in all but
3956 unusual installations.
3960 <tag><tt>Suggests</tt></tag>
3962 This is used to declare that one package may be more
3963 useful with one or more others. Using this field
3964 tells the packaging system and the user that the
3965 listed packages are related to this one and can
3966 perhaps enhance its usefulness, but that installing
3967 this one without them is perfectly reasonable.
3970 <tag><tt>Enhances</tt></tag>
3972 This field is similar to Suggests but works in the
3973 opposite direction. It is used to declare that a
3974 package can enhance the functionality of another
3978 <tag><tt>Pre-Depends</tt></tag>
3981 This field is like <tt>Depends</tt>, except that it
3982 also forces <prgn>dpkg</prgn> to complete installation
3983 of the packages named before even starting the
3984 installation of the package which declares the
3985 pre-dependency, as follows:
3989 When a package declaring a pre-dependency is about to
3990 be <em>unpacked</em> the pre-dependency can be
3991 satisfied if the depended-on package is either fully
3992 configured, <em>or even if</em> the depended-on
3993 package(s) are only unpacked or half-configured,
3994 provided that they have been configured correctly at
3995 some point in the past (and not removed or partially
3996 removed since). In this case, both the
3997 previously-configured and currently unpacked or
3998 half-configured versions must satisfy any version
3999 clause in the <tt>Pre-Depends</tt> field.
4003 When the package declaring a pre-dependency is about
4004 to be <em>configured</em>, the pre-dependency will be
4005 treated as a normal <tt>Depends</tt>, that is, it will
4006 be considered satisfied only if the depended-on
4007 package has been correctly configured.
4011 <tt>Pre-Depends</tt> should be used sparingly,
4012 preferably only by packages whose premature upgrade or
4013 installation would hamper the ability of the system to
4014 continue with any upgrade that might be in progress.
4018 <tt>Pre-Depends</tt> are also required if the
4019 <prgn>preinst</prgn> script depends on the named
4020 package. It is best to avoid this situation if
4028 When selecting which level of dependency to use you should
4029 consider how important the depended-on package is to the
4030 functionality of the one declaring the dependency. Some
4031 packages are composed of components of varying degrees of
4032 importance. Such a package should list using
4033 <tt>Depends</tt> the package(s) which are required by the
4034 more important components. The other components'
4035 requirements may be mentioned as Suggestions or
4036 Recommendations, as appropriate to the components' relative
4041 <sect id="conflicts">
4042 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4045 When one binary package declares a conflict with another
4046 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4047 refuse to allow them to be installed on the system at the
4052 If one package is to be installed, the other must be removed
4053 first - if the package being installed is marked as
4054 replacing (see <ref id="replaces">) the one on the system,
4055 or the one on the system is marked as deselected, or both
4056 packages are marked <tt>Essential</tt>, then
4057 <prgn>dpkg</prgn> will automatically remove the package
4058 which is causing the conflict, otherwise it will halt the
4059 installation of the new package with an error. This
4060 mechanism is specifically designed to produce an error when
4061 the installed package is <tt>Essential</tt>, but the new
4066 A package will not cause a conflict merely because its
4067 configuration files are still installed; it must be at least
4072 A special exception is made for packages which declare a
4073 conflict with their own package name, or with a virtual
4074 package which they provide (see below): this does not
4075 prevent their installation, and allows a package to conflict
4076 with others providing a replacement for it. You use this
4077 feature when you want the package in question to be the only
4078 package providing some feature.
4082 A <tt>Conflicts</tt> entry should almost never have an
4083 "earlier than" version clause. This would prevent
4084 <prgn>dpkg</prgn> from upgrading or installing the package
4085 which declared such a conflict until the upgrade or removal
4086 of the conflicted-with package had been completed.
4090 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4094 As well as the names of actual ("concrete") packages, the
4095 package relationship fields <tt>Depends</tt>,
4096 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4097 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4098 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4099 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4100 may mention "virtual packages".
4104 A <em>virtual package</em> is one which appears in the
4105 <tt>Provides</tt> control file field of another package.
4106 The effect is as if the package(s) which provide a
4107 particular virtual package name had been listed by name
4108 everywhere the virtual package name appears. (See also <ref
4113 If there are both concrete and virtual packages of the same
4114 name, then the dependency may be satisfied (or the conflict
4115 caused) by either the concrete package with the name in
4116 question or any other concrete package which provides the
4117 virtual package with the name in question. This is so that,
4118 for example, supposing we have
4119 <example compact="compact">
4123 and someone else releases an enhanced version of the
4124 <tt>bar</tt> package (for example, a non-US variant), they
4126 <example compact="compact">
4130 and the <tt>bar-plus</tt> package will now also satisfy the
4131 dependency for the <tt>foo</tt> package.
4135 If a dependency or a conflict has a version number attached
4136 then only real packages will be considered to see whether
4137 the relationship is satisfied (or the prohibition violated,
4138 for a conflict) - it is assumed that a real package which
4139 provides the virtual package is not of the "right" version.
4140 So, a <tt>Provides</tt> field may not contain version
4141 numbers, and the version number of the concrete package
4142 which provides a particular virtual package will not be
4143 looked at when considering a dependency on or conflict with
4144 the virtual package name.
4148 It is likely that the ability will be added in a future
4149 release of <prgn>dpkg</prgn> to specify a version number for
4150 each virtual package it provides. This feature is not yet
4151 present, however, and is expected to be used only
4156 If you want to specify which of a set of real packages
4157 should be the default to satisfy a particular dependency on
4158 a virtual package, you should list the real package as an
4159 alternative before the virtual one.
4164 <sect id="replaces"><heading>Overwriting files and replacing
4165 packages - <tt>Replaces</tt></heading>
4168 Packages can declare in their control file that they should
4169 overwrite files in certain other packages, or completely
4170 replace other packages. The <tt>Replaces</tt> control file
4171 field has these two distinct purposes.
4174 <sect1><heading>Overwriting files in other packages</heading>
4177 Firstly, as mentioned before, it is usually an error for a
4178 package to contain files which are on the system in
4183 However, if the overwriting package declares that it
4184 <tt>Replaces</tt> the one containing the file being
4185 overwritten, then <prgn>dpkg</prgn> will replace the file
4186 from the old package with that from the new. The file
4187 will no longer be listed as "owned" by the old package.
4191 If a package is completely replaced in this way, so that
4192 <prgn>dpkg</prgn> does not know of any files it still
4193 contains, it is considered to have "disappeared". It will
4194 be marked as not wanted on the system (selected for
4195 removal) and not installed. Any <tt>conffile</tt>s
4196 details noted for the package will be ignored, as they
4197 will have been taken over by the overwriting package. The
4198 package's <prgn>postrm</prgn> script will be run with a
4199 special argument to allow the package to do any final
4200 cleanup required. See <ref id="mscriptsinstact">.
4203 Replaces is a one way relationship -- you have to
4204 install the replacing package after the replaced
4211 For this usage of <tt>Replaces</tt>, virtual packages (see
4212 <ref id="virtual">) are not considered when looking at a
4213 <tt>Replaces</tt> field - the packages declared as being
4214 replaced must be mentioned by their real names.
4218 Furthermore, this usage of <tt>Replaces</tt> only takes
4219 effect when both packages are at least partially on the
4220 system at once, so that it can only happen if they do not
4221 conflict or if the conflict has been overridden.
4226 <sect1><heading>Replacing whole packages, forcing their
4230 Secondly, <tt>Replaces</tt> allows the packaging system to
4231 resolve which package should be removed when there is a
4232 conflict - see <ref id="conflicts">. This usage only
4233 takes effect when the two packages <em>do</em> conflict,
4234 so that the two usages of this field do not interfere with
4239 In this situation, the package declared as being replaced
4240 can be a virtual package, so for example, all mail
4241 transport agents (MTAs) would have the following fields in
4242 their control files:
4243 <example compact="compact">
4244 Provides: mail-transport-agent
4245 Conflicts: mail-transport-agent
4246 Replaces: mail-transport-agent
4248 ensuring that only one MTA can be installed at any one
4253 <sect id="sourcebinarydeps">
4254 <heading>Relationships between source and binary packages -
4255 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4256 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4260 Source packages that require certain binary packages to be
4261 installed or absent at the time of building the package
4262 can declare relationships to those binary packages.
4266 This is done using the <tt>Build-Depends</tt>,
4267 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4268 <tt>Build-Conflicts-Indep</tt> control file fields.
4272 Build-dependencies on "build-essential" binary packages can be
4273 omitted. Please see <ref id="pkg-relations"> for more information.
4277 The dependencies and conflicts they define must be satisfied
4278 (as defined earlier for binary packages) in order to invoke
4279 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4281 If you make "build-arch" or "binary-arch", you need
4282 Build-Depends. If you make "build-indep" or
4283 "binary-indep", you need Build-Depends and
4284 Build-Depends-Indep. If you make "build" or "binary",
4288 There is no Build-Depends-Arch; the autobuilders will
4289 only need the Build-Depends if they know how to build
4290 only build-arch and binary-arch. Anyone building the
4291 build-indep/binary-indep targets is basically assumed to
4292 be building the whole package and so installs all build
4296 The purpose of the original split, I recall, was so that
4297 the autobuilders wouldn't need to install extra packages
4298 needed only for the binary-indep targets. But without a
4299 build-arch/build-indep split, this didn't work, since
4300 most of the work is done in the build target, not in the
4306 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4308 The <tt>Build-Depends</tt> and
4309 <tt>Build-Conflicts</tt> fields must be satisfied when
4310 any of the following targets is invoked:
4311 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4312 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4313 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4315 <tag><tt>Build-Depends-Indep</tt>,
4316 <tt>Build-Conflicts-Indep</tt></tag>
4318 The <tt>Build-Depends-Indep</tt> and
4319 <tt>Build-Conflicts-Indep</tt> fields must be
4320 satisfied when any of the following targets is
4321 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4322 <tt>binary</tt> and <tt>binary-indep</tt>.
4332 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4335 Packages containing shared libraries must be constructed with
4336 a little care to make sure that the shared library is always
4337 available. This is especially important for packages whose
4338 shared libraries are vitally important, such as the C library
4339 (currently <tt>libc6</tt>).
4343 Packages involving shared libraries should be split up into
4344 several binary packages. This section mostly deals with how
4345 this separation is to be accomplished; rules for files within
4346 the shared library packages are in <ref id="libraries"> instead.
4349 <sect id="sharedlibs-runtime">
4350 <heading>Run-time shared libraries</heading>
4353 The run-time shared library needs to be placed in a package
4354 whose name changes whenever the shared object version
4357 Since it is common place to install several versions of a
4358 package that just provides shared libraries, it is a
4359 good idea that that the library package should not
4360 contain any extraneous non-versioned files, unless they
4361 happen to be in versioned directories.</p>
4363 The most common mechanism is to place it in a package
4365 <package><var>libraryname</var><var>soversion</var></package>,
4366 where <file><var>soversion</var></file> is the version number
4367 in the soname of the shared library<footnote>
4368 The soname is the shared object name: it's the thing
4369 that has to match exactly between building an executable
4370 and running it for the dynamic linker to be able run the
4371 program. For example, if the soname of the library is
4372 <file>libfoo.so.6</file>, the library package would be
4373 called <file>libfoo6</file>.
4375 Alternatively, if it would be confusing to directly append
4376 <var>soversion</var> to <var>libraryname</var> (e.g. because
4377 <var>libraryname</var> itself ends in a number), you may use
4378 <package><var>libraryname</var>-<var>soversion</var></package> and
4379 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4383 If you have several shared libraries built from the same
4384 source tree you may lump them all together into a single
4385 shared library package, provided that you change all of
4386 their sonames at once (so that you don't get filename
4387 clashes if you try to install different versions of the
4388 combined shared libraries package).
4392 The package should install the shared libraries under
4393 their normal names. For example, the <package>libgdbm3</package>
4394 package should install <file>libgdbm.so.3.0.0</file> as
4395 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4396 renamed or re-linked by any <prgn>prerm</prgn> or
4397 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4398 of renaming things safely without affecting running programs,
4399 and attempts to interfere with this are likely to lead to
4404 Shared libraries should not be installed executable, since
4405 the dynamic linker does not require this and trying to
4406 execute a shared library usually results in a core dump.
4410 The run-time library package should include the symbolic link that
4411 <prgn>ldconfig</prgn> would create for the shared libraries.
4412 For example, the <package>libgdbm3</package> package should include
4413 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4414 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4415 linker (for example <prgn>ld.so</prgn> or
4416 <prgn>ld-linux.so.*</prgn>) can find the library between the
4417 time that <prgn>dpkg</prgn> installs it and the time that
4418 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4420 The package management system requires the library to be
4421 placed before the symbolic link pointing to it in the
4422 <file>.deb</file> file. This is so that when
4423 <prgn>dpkg</prgn> comes to install the symlink
4424 (overwriting the previous symlink pointing at an older
4425 version of the library), the new shared library is already
4426 in place. In the past, this was achieved by creating the
4427 library in the temporary packaging directory before
4428 creating the symlink. Unfortunately, this was not always
4429 effective, since the building of the tar file in the
4430 <file>.deb</file> depended on the behavior of the underlying
4431 file system. Some file systems (such as reiserfs) reorder
4432 the files so that the order of creation is forgotten.
4433 Since version 1.7.0, <prgn>dpkg</prgn>
4434 reorders the files itself as necessary when building a
4435 package. Thus it is no longer important to concern
4436 oneself with the order of file creation.
4440 <sect1 id="ldconfig">
4441 <heading><tt>ldconfig</tt></heading>
4444 Any package installing shared libraries in one of the default
4445 library directories of the dynamic linker (which are currently
4446 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4447 listed in <file>/etc/ld.so.conf</file><footnote>
4449 <list compact="compact">
4450 <item>/usr/X11R6/lib/Xaw3d</item>
4451 <item>/usr/local/lib</item>
4452 <item>/usr/lib/libc5-compat</item>
4453 <item>/lib/libc5-compat</item>
4454 <item>/usr/X11R6/lib</item>
4457 must use <prgn>ldconfig</prgn> to update the shared library
4462 The package must call <prgn>ldconfig</prgn> in the
4463 <prgn>postinst</prgn> script if the first argument is
4464 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4465 optionally invoke <prgn>ldconfig</prgn> at other times. The
4466 package should call <prgn>ldconfig</prgn> in the
4467 <prgn>postrm</prgn> script if the first argument is
4468 <tt>remove</tt>. The maintainer scripts must not invoke
4469 <prgn>ldconfig</prgn> under any circumstances other than those
4470 described in this paragraph.<footnote>
4472 During install or upgrade, the preinst is called before
4473 the new files are installed, so calling "ldconfig" is
4474 pointless. The preinst of an existing package can also be
4475 called if an upgrade fails. However, this happens during
4476 the critical time when a shared libs may exist on-disk
4477 under a temporary name. Thus, it is dangerous and
4478 forbidden by current policy to call "ldconfig" at this
4483 When a package is installed or upgraded, "postinst
4484 configure" runs after the new files are safely on-disk.
4485 Since it is perfectly safe to invoke ldconfig
4486 unconditionally in a postinst, it is OK for a package to
4487 simply put ldconfig in its postinst without checking the
4488 argument. The postinst can also be called to recover from
4489 a failed upgrade. This happens before any new files are
4490 unpacked, so there is no reason to call "ldconfig" at this
4495 For a package that is being removed, prerm is
4496 called with all the files intact, so calling ldconfig is
4497 useless. The other calls to "prerm" happen in the case of
4498 upgrade at a time when all the files of the old package
4499 are on-disk, so again calling "ldconfig" is pointless.
4503 postrm, on the other hand, is called with the "remove"
4504 argument just after the files are removed, so this is the
4505 proper time to call "ldconfig" to notify the system of the
4506 fact shared libraries from the package are removed.
4507 The postrm can be called at several other times. At the
4508 time of "postrm purge", "postrm abort-install", or "postrm
4509 abort-upgrade", calling "ldconfig" is useless because the
4510 shared lib files are not on-disk. However, when "postrm"
4511 is invoked with arguments "upgrade", "failed-upgrade", or
4512 "disappear", a shared lib may exist on-disk under a
4521 <sect id="sharedlibs-runtime-progs">
4522 <heading>Run-time support programs</heading>
4525 If your package has some run-time support programs which use
4526 the shared library you must not put them in the shared
4527 library package. If you do that then you won't be able to
4528 install several versions of the shared library without
4529 getting filename clashes.
4533 Instead, either create another package for the runtime binaries
4534 (this package might typically be named
4535 <package><var>libraryname</var>-runtime</package>; note the absence
4536 of the <var>soversion</var> in the package name), or if the
4537 development package is small, include them in there.
4541 <sect id="sharedlibs-static">
4542 <heading>Static libraries</heading>
4545 The static library (<file><var>libraryname.a</var></file>)
4546 is usually provided in addition to the shared version.
4547 It is placed into the development package (see below).
4551 In some cases, it is acceptable for a library to be
4552 available in static form only; these cases include:
4554 <item>libraries for languages whose shared library support
4555 is immature or unstable</item>
4556 <item>libraries whose interfaces are in flux or under
4557 development (commonly the case when the library's
4558 major version number is zero, or where the ABI breaks
4559 across patchlevels)</item>
4560 <item>libraries which are explicitly intended to be
4561 available only in static form by their upstream
4566 <sect id="sharedlibs-dev">
4567 <heading>Development files</heading>
4570 The development files associated to a shared library need to be
4571 placed in a package called
4572 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4573 or if you prefer only to support one development version at a
4574 time, <package><var>libraryname</var>-dev</package>.
4578 In case several development versions of a library exist, you may
4579 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4580 <ref id="conflicts">) to ensure that the user only installs one
4581 development version at a time (as different development versions are
4582 likely to have the same header files in them, which would cause a
4583 filename clash if both were installed).
4587 The development package should contain a symlink for the associated
4588 shared library without a version number. For example, the
4589 <package>libgdbm-dev</package> package should include a symlink
4590 from <file>/usr/lib/libgdbm.so</file> to
4591 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4592 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4593 <file>libgdbm.so</file> when compiling dynamically.
4597 <sect id="sharedlibs-intradeps">
4598 <heading>Dependencies between the packages of the same library</heading>
4601 Typically the development version should have an exact
4602 version dependency on the runtime library, to make sure that
4603 compilation and linking happens correctly. The
4604 <tt>${Source-Version}</tt> substitution variable can be
4605 useful for this purpose.
4609 <sect id="sharedlibs-shlibdeps">
4610 <heading>Dependencies between the library and other packages -
4611 the <tt>shlibs</tt> system</heading>
4614 If a package contains a binary or library which links to a
4615 shared library, we must ensure that when the package is
4616 installed on the system, all of the libraries needed are
4617 also installed. This requirement led to the creation of the
4618 <tt>shlibs</tt> system, which is very simple in its design:
4619 any package which <em>provides</em> a shared library also
4620 provides information on the package dependencies required to
4621 ensure the presence of this library, and any package which
4622 <em>uses</em> a shared library uses this information to
4623 determine the dependencies it requires. The files which
4624 contain the mapping from shared libraries to the necessary
4625 dependency information are called <file>shlibs</file> files.
4629 Thus, when a package is built which contains any shared
4630 libraries, it must provide a <file>shlibs</file> file for other
4631 packages to use, and when a package is built which contains
4632 any shared libraries or compiled binaries, it must run
4633 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4634 on these to determine the libraries used and hence the
4635 dependencies needed by this package.<footnote>
4637 In the past, the shared libraries linked to were
4638 determined by calling <prgn>ldd</prgn>, but now
4639 <prgn>objdump</prgn> is used to do this. The only
4640 change this makes to package building is that
4641 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4642 libraries, whereas in the past this was unnecessary.
4643 The rest of this footnote explains the advantage that
4648 We say that a binary <tt>foo</tt> <em>directly</em> uses
4649 a library <tt>libbar</tt> if it is explicitly linked
4650 with that library (that is, it uses the flag
4651 <tt>-lbar</tt> during the linking stage). Other
4652 libraries that are needed by <tt>libbar</tt> are linked
4653 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4654 linker will load them automatically when it loads
4655 <tt>libbar</tt>. A package should depend on
4656 the libraries it directly uses, and the dependencies for
4657 those libraries should automatically pull in the other
4662 Unfortunately, the <prgn>ldd</prgn> program shows both
4663 the directly and indirectly used libraries, meaning that
4664 the dependencies determined included both direct and
4665 indirect dependencies. The use of <prgn>objdump</prgn>
4666 avoids this problem by determining only the directly
4671 A good example of where this helps is the following. We
4672 could update <tt>libimlib</tt> with a new version that
4673 supports a new graphics format called dgf (but retaining
4674 the same major version number). If we used the old
4675 <prgn>ldd</prgn> method, every package that uses
4676 <tt>libimlib</tt> would need to be recompiled so it
4677 would also depend on <tt>libdgf</tt> or it wouldn't run
4678 due to missing symbols. However with the new system,
4679 packages using <tt>libimlib</tt> can rely on
4680 <tt>libimlib</tt> itself having the dependency on
4681 <tt>libdgf</tt> and so they would not need rebuilding.
4687 In the following sections, we will first describe where the
4688 various <tt>shlibs</tt> files are to be found, then how to
4689 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4690 file format and how to create them if your package contains a
4695 <heading>The <tt>shlibs</tt> files present on the system</heading>
4698 There are several places where <tt>shlibs</tt> files are
4699 found. The following list gives them in the order in which
4701 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4702 (The first one which gives the required information is used.)
4708 <p><file>debian/shlibs.local</file></p>
4711 This lists overrides for this package. Its use is
4712 described below (see <ref id="shlibslocal">).
4717 <p><file>/etc/dpkg/shlibs.override</file></p>
4720 This lists global overrides. This list is normally
4721 empty. It is maintained by the local system
4727 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4730 When packages are being built, any
4731 <file>debian/shlibs</file> files are copied into the
4732 control file area of the temporary build directory and
4733 given the name <file>shlibs</file>. These files give
4734 details of any shared libraries included in the
4736 An example may help here. Let us say that the
4737 source package <tt>foo</tt> generates two binary
4738 packages, <tt>libfoo2</tt> and
4739 <tt>foo-runtime</tt>. When building the binary
4740 packages, the two packages are created in the
4741 directories <file>debian/libfoo2</file> and
4742 <file>debian/foo-runtime</file> respectively.
4743 (<file>debian/tmp</file> could be used instead of one
4744 of these.) Since <tt>libfoo2</tt> provides the
4745 <tt>libfoo</tt> shared library, it will require a
4746 <tt>shlibs</tt> file, which will be installed in
4747 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4749 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4750 when <prgn>dpkg-shlibdeps</prgn> is run on the
4752 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4754 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4755 determine whether <tt>foo-prog</tt>'s library
4756 dependencies are satisfied by any of the libraries
4757 provided by <tt>libfoo2</tt>. For this reason,
4758 <prgn>dpkg-shlibdeps</prgn> must only be run once
4759 all of the individual binary packages'
4760 <tt>shlibs</tt> files have been installed into the
4767 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4770 These are the <file>shlibs</file> files corresponding to
4771 all of the packages installed on the system, and are
4772 maintained by the relevant package maintainers.
4777 <p><file>/etc/dpkg/shlibs.default</file></p>
4780 This file lists any shared libraries whose packages
4781 have failed to provide correct <file>shlibs</file> files.
4782 It was used when the <file>shlibs</file> setup was first
4783 introduced, but it is now normally empty. It is
4784 maintained by the <tt>dpkg</tt> maintainer.
4792 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4793 <file>shlibs</file> files</heading>
4797 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4798 into your <file>debian/rules</file> file. If your package
4799 contains only compiled binaries and libraries (but no scripts),
4800 you can use a command such as:
4801 <example compact="compact">
4802 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4803 debian/tmp/usr/lib/*
4805 Otherwise, you will need to explicitly list the compiled
4806 binaries and libraries.<footnote>
4807 If you are using <tt>debhelper</tt>, the
4808 <prgn>dh_shlibdeps</prgn> program will do this work for
4809 you. It will also correctly handle multi-binary
4815 This command puts the dependency information into the
4816 <file>debian/substvars</file> file, which is then used by
4817 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4818 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4819 field in the control file for this to work.
4823 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4824 done. If it does complain you might need to create your own
4825 <file>debian/shlibs.local</file> file, as explained below (see
4826 <ref id="shlibslocal">).
4830 If you have multiple binary packages, you will need to call
4831 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4832 compiled libraries or binaries. In such a case, you will
4833 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4834 utilities to specify a different <file>substvars</file> file.
4838 For more details on dpkg-shlibdeps, please see
4839 <ref id="pkg-dpkg-shlibdeps"> and
4840 <manref name="dpkg-shlibdeps" section="1">.
4845 <heading>The <file>shlibs</file> File Format</heading>
4848 Each <file>shlibs</file> file has the same format. Lines
4849 beginning with <tt>#</tt> are considered to be comments and
4850 are ignored. Each line is of the form:
4851 <example compact="compact">
4852 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4857 We will explain this by reference to the example of the
4858 <tt>zlib1g</tt> package, which (at the time of writing)
4859 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4863 <var>library-name</var> is the name of the shared library,
4864 in this case <tt>libz</tt>. (This must match the name part
4865 of the soname, see below.)
4869 <var>soname-version-number</var> is the version part of the
4870 soname of the library. The soname is the thing that must
4871 exactly match for the library to be recognized by the
4872 dynamic linker, and is usually of the form
4873 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4874 example, <tt>libz.so.1</tt>.<footnote>
4875 This can be determined using the command
4876 <example compact="compact">
4877 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4880 The version part is the part which comes after
4881 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4885 <var>dependencies</var> has the same syntax as a dependency
4886 field in a binary package control file. It should give
4887 details of which packages are required to satisfy a binary
4888 built against the version of the library contained in the
4889 package. See <ref id="depsyntax"> for details.
4893 In our example, if the first version of the <tt>zlib1g</tt>
4894 package which contained a minor number of at least
4895 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4896 <tt>shlibs</tt> entry for this library could say:
4897 <example compact="compact">
4898 libz 1 zlib1g (>= 1:1.1.3)
4900 The version-specific dependency is to avoid warnings from
4901 the dynamic linker about using older shared libraries with
4907 <heading>Providing a <file>shlibs</file> file</heading>
4910 If your package provides a shared library, you should create
4911 a <file>shlibs</file> file following the format described above.
4912 It is usual to call this file <file>debian/shlibs</file> (but if
4913 you have multiple binary packages, you might want to call it
4914 <file>debian/shlibs.<var>package</var></file> instead). Then
4915 let <file>debian/rules</file> install it in the control area:
4916 <example compact="compact">
4917 install -m644 debian/shlibs debian/tmp/DEBIAN
4919 or, in the case of a multi-binary package:
4920 <example compact="compact">
4921 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4923 An alternative way of doing this is to create the
4924 <file>shlibs</file> file in the control area directly from
4925 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4926 file at all,<footnote>
4927 This is what <prgn>dh_makeshlibs</prgn> in the
4928 <tt>debhelper</tt> suite does.
4930 since the <file>debian/shlibs</file> file itself is ignored by
4931 <prgn>dpkg-shlibdeps</prgn>.
4935 As <prgn>dpkg-shlibdeps</prgn> reads the
4936 <file>DEBIAN/shlibs</file> files in all of the binary packages
4937 being built from this source package, all of the
4938 <file>DEBIAN/shlibs</file> files should be installed before
4939 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4944 <sect1 id="shlibslocal">
4945 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4948 This file is intended only as a <em>temporary</em> fix if
4949 your binaries or libraries depend on a library whose package
4950 does not yet provide a correct <file>shlibs</file> file.
4954 We will assume that you are trying to package a binary
4955 <tt>foo</tt>. When you try running
4956 <prgn>dpkg-shlibdeps</prgn> you get the following error
4957 message (<tt>-O</tt> displays the dependency information on
4958 <tt>stdout</tt> instead of writing it to
4959 <tt>debian/substvars</tt>, and the lines have been wrapped
4960 for ease of reading):
4961 <example compact="compact">
4962 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4963 dpkg-shlibdeps: warning: unable to find dependency
4964 information for shared library libbar (soname 1,
4965 path /usr/lib/libbar.so.1, dependency field Depends)
4966 shlibs:Depends=libc6 (>= 2.2.2-2)
4968 You can then run <prgn>ldd</prgn> on the binary to find the
4969 full location of the library concerned:
4970 <example compact="compact">
4972 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4973 libc.so.6 => /lib/libc.so.6 (0x40032000)
4974 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4976 So the <prgn>foo</prgn> binary depends on the
4977 <prgn>libbar</prgn> shared library, but no package seems to
4978 provide a <file>*.shlibs</file> file handling
4979 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4980 determine the package responsible:
4981 <example compact="compact">
4982 $ dpkg -S /usr/lib/libbar.so.1
4983 bar1: /usr/lib/libbar.so.1
4984 $ dpkg -s bar1 | grep Version
4987 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4988 is the one we are using. Now we can file a bug against the
4989 <tt>bar1</tt> package and create our own
4990 <file>debian/shlibs.local</file> to locally fix the problem.
4991 Including the following line into your
4992 <file>debian/shlibs.local</file> file:
4993 <example compact="compact">
4994 libbar 1 bar1 (>= 1.0-1)
4996 should allow the package build to work.
5000 As soon as the maintainer of <tt>bar1</tt> provides a
5001 correct <file>shlibs</file> file, you should remove this line
5002 from your <file>debian/shlibs.local</file> file. (You should
5003 probably also then have a versioned <tt>Build-Depends</tt>
5004 on <tt>bar1</tt> to help ensure that others do not have the
5005 same problem building your package.)
5014 <chapt id="opersys"><heading>The Operating System</heading>
5017 <heading>Filesystem hierarchy</heading>
5021 <heading>Filesystem Structure</heading>
5024 The location of all installed files and directories must
5025 comply with the Filesystem Hierarchy Standard (FHS),
5026 version 2.1, except where doing so would violate other
5027 terms of Debian Policy. The version of this document
5028 referred here can be found in the <tt>debian-policy</tt>
5030 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5031 name="FHS (Debian copy)"> alongside this manual (or, if
5032 you have the <package>debian-policy</package> installed,
5034 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5035 (local copy)">). The
5036 latest version, which may be a more recent version, may
5038 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5039 Specific questions about following the standard may be
5040 asked on the <tt>debian-devel</tt> mailing list, or
5041 referred to the FHS mailing list (see the
5042 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5048 <heading>Site-specific programs</heading>
5051 As mandated by the FHS, packages must not place any
5052 files in <file>/usr/local</file>, either by putting them in
5053 the file system archive to be unpacked by <prgn>dpkg</prgn>
5054 or by manipulating them in their maintainer scripts.
5058 However, the package may create empty directories below
5059 <file>/usr/local</file> so that the system administrator knows
5060 where to place site-specific files. These directories
5061 should be removed on package removal if they are
5066 Note, that this applies only to directories <em>below</em>
5067 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5068 Packages must not create sub-directories in the directory
5069 <file>/usr/local</file> itself, except those listed in FHS,
5070 section 4.5. However, you may create directories below
5071 them as you wish. You must not remove any of the
5072 directories listed in 4.5, even if you created them.
5076 Since <file>/usr/local</file> can be mounted read-only from a
5077 remote server, these directories must be created and
5078 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5079 maintainer scripts and not be included in the
5080 <file>.deb</file> archive. These scripts must not fail if
5081 either of these operations fail.
5085 For example, the <tt>emacsen-common</tt> package could
5086 contain something like
5087 <example compact="compact">
5088 if [ ! -e /usr/local/share/emacs ]
5090 if mkdir /usr/local/share/emacs 2>/dev/null
5092 chown root:staff /usr/local/share/emacs
5093 chmod 2775 /usr/local/share/emacs
5097 in its <prgn>postinst</prgn> script, and
5098 <example compact="compact">
5099 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5100 rmdir /usr/local/share/emacs 2>/dev/null || true
5102 in the <prgn>prerm</prgn> script. (Note that this form is
5103 used to ensure that if the script is interrupted, the
5104 directory <file>/usr/local/share/emacs</file> will still be
5109 If you do create a directory in <file>/usr/local</file> for
5110 local additions to a package, you should ensure that
5111 settings in <file>/usr/local</file> take precedence over the
5112 equivalents in <file>/usr</file>.
5116 However, because <file>/usr/local</file> and its contents are
5117 for exclusive use of the local administrator, a package
5118 must not rely on the presence or absence of files or
5119 directories in <file>/usr/local</file> for normal operation.
5123 The <file>/usr/local</file> directory itself and all the
5124 subdirectories created by the package should (by default) have
5125 permissions 2775 (group-writable and set-group-id) and be
5126 owned by <tt>root.staff</tt>.
5131 <heading>The system-wide mail directory</heading>
5133 The system-wide mail directory is <file>/var/mail</file>. This
5134 directory is part of the base system and should not owned
5135 by any particular mail agents. The use of the old
5136 location <file>/var/spool/mail</file> is deprecated, even
5137 though the spool may still be physically located there.
5138 To maintain partial upgrade compatibility for systems
5139 which have <file>/var/spool/mail</file> as their physical mail
5140 spool, packages using <file>/var/mail</file> must depend on
5141 either <package>libc6</package> (>= 2.1.3-13), or on
5142 <package>base-files</package> (>= 2.2.0), or on later
5143 versions of either one of these packages.
5149 <heading>Users and groups</heading>
5152 <heading>Introduction</heading>
5154 The Debian system can be configured to use either plain or
5159 Some user ids (UIDs) and group ids (GIDs) are reserved
5160 globally for use by certain packages. Because some
5161 packages need to include files which are owned by these
5162 users or groups, or need the ids compiled into binaries,
5163 these ids must be used on any Debian system only for the
5164 purpose for which they are allocated. This is a serious
5165 restriction, and we should avoid getting in the way of
5166 local administration policies. In particular, many sites
5167 allocate users and/or local system groups starting at 100.
5171 Apart from this we should have dynamically allocated ids,
5172 which should by default be arranged in some sensible
5173 order, but the behavior should be configurable.
5177 Packages other than <tt>base-passwd</tt> must not modify
5178 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5179 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5184 <heading>UID and GID classes</heading>
5186 The UID and GID numbers are divided into classes as
5192 Globally allocated by the Debian project, the same
5193 on every Debian system. These ids will appear in
5194 the <file>passwd</file> and <file>group</file> files of all
5195 Debian systems, new ids in this range being added
5196 automatically as the <tt>base-passwd</tt> package is
5201 Packages which need a single statically allocated
5202 uid or gid should use one of these; their
5203 maintainers should ask the <tt>base-passwd</tt>
5211 Dynamically allocated system users and groups.
5212 Packages which need a user or group, but can have
5213 this user or group allocated dynamically and
5214 differently on each system, should use <tt>adduser
5215 --system</tt> to create the group and/or user.
5216 <prgn>adduser</prgn> will check for the existence of
5217 the user or group, and if necessary choose an unused
5218 id based on the ranges specified in
5219 <file>adduser.conf</file>.
5223 <tag>1000-29999:</tag>
5226 Dynamically allocated user accounts. By default
5227 <prgn>adduser</prgn> will choose UIDs and GIDs for
5228 user accounts in this range, though
5229 <file>adduser.conf</file> may be used to modify this
5234 <tag>30000-59999:</tag>
5239 <tag>60000-64999:</tag>
5242 Globally allocated by the Debian project, but only
5243 created on demand. The ids are allocated centrally
5244 and statically, but the actual accounts are only
5245 created on users' systems on demand.
5249 These ids are for packages which are obscure or
5250 which require many statically-allocated ids. These
5251 packages should check for and create the accounts in
5252 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5253 <prgn>adduser</prgn> if it has this facility) if
5254 necessary. Packages which are likely to require
5255 further allocations should have a "hole" left after
5256 them in the allocation, to give them room to
5261 <tag>65000-65533:</tag>
5269 User <tt>nobody</tt>. The corresponding gid refers
5270 to the group <tt>nogroup</tt>.
5277 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5278 not</em> be used, because it is the error return
5287 <sect id="sysvinit">
5288 <heading>System run levels and <file>init.d</file> scripts</heading>
5290 <sect1 id="/etc/init.d">
5291 <heading>Introduction</heading>
5294 The <file>/etc/init.d</file> directory contains the scripts
5295 executed by <prgn>init</prgn> at boot time and when the
5296 init state (or "runlevel") is changed (see <manref
5297 name="init" section="8">).
5301 There are at least two different, yet functionally
5302 equivalent, ways of handling these scripts. For the sake
5303 of simplicity, this document describes only the symbolic
5304 link method. However, it must not be assumed by maintainer
5305 scripts that this method is being used, and any automated
5306 manipulation of the various runlevel behaviours by
5307 maintainer scripts must be performed using
5308 <prgn>update-rc.d</prgn> as described below and not by
5309 manually installing or removing symlinks. For information
5310 on the implementation details of the other method,
5311 implemented in the <tt>file-rc</tt> package, please refer
5312 to the documentation of that package.
5316 These scripts are referenced by symbolic links in the
5317 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5318 runlevels, <prgn>init</prgn> looks in the directory
5319 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5320 execute, where <tt><var>n</var></tt> is the runlevel that
5321 is being changed to, or <tt>S</tt> for the boot-up
5326 The names of the links all have the form
5327 <file>S<var>mm</var><var>script</var></file> or
5328 <file>K<var>mm</var><var>script</var></file> where
5329 <var>mm</var> is a two-digit number and <var>script</var>
5330 is the name of the script (this should be the same as the
5331 name of the actual script in <file>/etc/init.d</file>).
5335 When <prgn>init</prgn> changes runlevel first the targets
5336 of the links whose names start with a <tt>K</tt> are
5337 executed, each with the single argument <tt>stop</tt>,
5338 followed by the scripts prefixed with an <tt>S</tt>, each
5339 with the single argument <tt>start</tt>. (The links are
5340 those in the <file>/etc/rc<var>n</var>.d</file> directory
5341 corresponding to the new runlevel.) The <tt>K</tt> links
5342 are responsible for killing services and the <tt>S</tt>
5343 link for starting services upon entering the runlevel.
5347 For example, if we are changing from runlevel 2 to
5348 runlevel 3, init will first execute all of the <tt>K</tt>
5349 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5350 all of the <tt>S</tt> prefixed scripts in that directory.
5351 The links starting with <tt>K</tt> will cause the
5352 referred-to file to be executed with an argument of
5353 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5358 The two-digit number <var>mm</var> is used to determine
5359 the order in which to run the scripts: low-numbered links
5360 have their scripts run first. For example, the
5361 <tt>K20</tt> scripts will be executed before the
5362 <tt>K30</tt> scripts. This is used when a certain service
5363 must be started before another. For example, the name
5364 server <prgn>bind</prgn> might need to be started before
5365 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5366 can set up its access lists. In this case, the script
5367 that starts <prgn>bind</prgn> would have a lower number
5368 than the script that starts <prgn>inn</prgn> so that it
5370 <example compact="compact">
5377 The two runlevels 0 (halt) and 6 (reboot) are slightly
5378 different. In these runlevels, the links with an
5379 <tt>S</tt> prefix are still called after those with a
5380 <tt>K</tt> prefix, but they too are called with the single
5381 argument <tt>stop</tt>.
5385 Also, if the script name ends <tt>.sh</tt>, the script
5386 will be sourced in runlevel <tt>S</tt> rather that being
5387 run in a forked subprocess, but will be explicitly run by
5388 <prgn>sh</prgn> in all other runlevels.
5393 <heading>Writing the scripts</heading>
5396 Packages that include daemons for system services should
5397 place scripts in <file>/etc/init.d</file> to start or stop
5398 services at boot time or during a change of runlevel.
5399 These scripts should be named
5400 <file>/etc/init.d/<var>package</var></file>, and they should
5401 accept one argument, saying what to do:
5404 <tag><tt>start</tt></tag>
5405 <item>start the service,</item>
5407 <tag><tt>stop</tt></tag>
5408 <item>stop the service,</item>
5410 <tag><tt>restart</tt></tag>
5411 <item>stop and restart the service if it's already running,
5412 otherwise start the service</item>
5414 <tag><tt>reload</tt></tag>
5415 <item><p>cause the configuration of the service to be
5416 reloaded without actually stopping and restarting
5419 <tag><tt>force-reload</tt></tag>
5420 <item>cause the configuration to be reloaded if the
5421 service supports this, otherwise restart the
5425 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5426 <tt>force-reload</tt> options should be supported by all
5427 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5432 The <file>init.d</file> scripts should ensure that they will
5433 behave sensibly if invoked with <tt>start</tt> when the
5434 service is already running, or with <tt>stop</tt> when it
5435 isn't, and that they don't kill unfortunately-named user
5436 processes. The best way to achieve this is usually to use
5437 <prgn>start-stop-daemon</prgn>.
5441 If a service reloads its configuration automatically (as
5442 in the case of <prgn>cron</prgn>, for example), the
5443 <tt>reload</tt> option of the <file>init.d</file> script
5444 should behave as if the configuration has been reloaded
5449 The <file>/etc/init.d</file> scripts must be treated as
5450 configuration files, either (if they are present in the
5451 package, that is, in the .deb file) by marking them as
5452 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5453 by managing them correctly in the maintainer scripts (see
5454 <ref id="config-files">). This is important since we want
5455 to give the local system administrator the chance to adapt
5456 the scripts to the local system, e.g., to disable a
5457 service without de-installing the package, or to specify
5458 some special command line options when starting a service,
5459 while making sure their changes aren't lost during the next
5464 These scripts should not fail obscurely when the
5465 configuration files remain but the package has been
5466 removed, as configuration files remain on the system after
5467 the package has been removed. Only when <prgn>dpkg</prgn>
5468 is executed with the <tt>--purge</tt> option will
5469 configuration files be removed. In particular, as the
5470 <file>/etc/init.d/<var>package</var></file> script itself is
5471 usually a <tt>conffile</tt>, it will remain on the system
5472 if the package is removed but not purged. Therefore, you
5473 should include a <tt>test</tt> statement at the top of the
5475 <example compact="compact">
5476 test -f <var>program-executed-later-in-script</var> || exit 0
5481 Often there are some variables in the <file>init.d</file>
5482 scripts whose values control the behaviour of the scripts,
5483 and which a system administrator is likely to want to
5484 change. As the scripts themselves are frequently
5485 <tt>conffile</tt>s, modifying them requires that the
5486 administrator merge in their changes each time the package
5487 is upgraded and the <tt>conffile</tt> changes. To ease
5488 the burden on the system administrator, such configurable
5489 values should not be placed directly in the script.
5490 Instead, they should be placed in a file in
5491 <file>/etc/default</file>, which typically will have the same
5492 base name as the <file>init.d</file> script. This extra file
5493 should be sourced by the script when the script runs. It
5494 must contain only variable settings and comments in POSIX
5495 <prgn>sh</prgn> format. It may either be a
5496 <tt>conffile</tt> or a configuration file maintained by
5497 the package maintainer scripts. See <ref id="config-files">
5502 To ensure that vital configurable values are always
5503 available, the <file>init.d</file> script should set default
5504 values for each of the shell variables it uses, either
5505 before sourcing the <file>/etc/default/</file> file or
5506 afterwards using something like the <tt>:
5507 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5508 script must behave sensibly and not fail if the
5509 <file>/etc/default</file> file is deleted.
5514 <heading>Interfacing with the initscript system</heading>
5517 Maintainers should use the abstraction layer provided by
5518 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5519 programs to deal with initscripts in their packages'
5520 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5521 and <prgn>postrm</prgn>.
5525 Directly managing the /etc/rc?.d links and directly
5526 invoking the <file>/etc/init.d/</file> initscripts should
5527 be done only by packages providing the initscript
5528 subsystem (such as <prgn>sysv-rc</prgn> and
5529 <prgn>file-rc</prgn>).
5533 <heading>Managing the links</heading>
5536 The program <prgn>update-rc.d</prgn> is provided for
5537 package maintainers to arrange for the proper creation and
5538 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5539 or their functional equivalent if another method is being
5540 used. This may be used by maintainers in their packages'
5541 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5545 You must not include any <file>/etc/rc<var>n</var>.d</file>
5546 symbolic links in the actual archive or manually create or
5547 remove the symbolic links in maintainer scripts; you must
5548 use the <prgn>update-rc.d</prgn> program instead. (The
5549 former will fail if an alternative method of maintaining
5550 runlevel information is being used.) You must not include
5551 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5552 in the archive either. (Only the <tt>sysvinit</tt>
5557 By default <prgn>update-rc.d</prgn> will start services in
5558 each of the multi-user state runlevels (2, 3, 4, and 5)
5559 and stop them in the halt runlevel (0), the single-user
5560 runlevel (1) and the reboot runlevel (6). The system
5561 administrator will have the opportunity to customize
5562 runlevels by simply adding, moving, or removing the
5563 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5564 symbolic links are being used, or by modifying
5565 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5570 To get the default behavior for your package, put in your
5571 <prgn>postinst</prgn> script
5572 <example compact="compact">
5573 update-rc.d <var>package</var> defaults
5575 and in your <prgn>postrm</prgn>
5576 <example compact="compact">
5577 if [ "$1" = purge ]; then
5578 update-rc.d <var>package</var> remove
5580 </example>. Note that if your package changes runlevels
5581 or priority, you may have to remove and recreate the links,
5582 since otherwise the old links may persist. Refer to the
5583 documentation of <prgn>update-rc.d</prgn>.
5587 This will use a default sequence number of 20. If it does
5588 not matter when or in which order the <file>init.d</file>
5589 script is run, use this default. If it does, then you
5590 should talk to the maintainer of the <prgn>sysvinit</prgn>
5591 package or post to <tt>debian-devel</tt>, and they will
5592 help you choose a number.
5596 For more information about using <tt>update-rc.d</tt>,
5597 please consult its man page <manref name="update-rc.d"
5603 <heading>Running initscripts</heading>
5605 The program <prgn>invoke-rc.d</prgn> is provided to make
5606 it easier for package maintainers to properly invoke an
5607 initscript, obeying runlevel and other locally-defined
5608 constraints that might limit a package's right to start,
5609 stop and otherwise manage services. This program may be
5610 used by maintainers in their packages' scripts.
5614 The use of <prgn>invoke-rc.d</prgn> to invoke the
5615 <file>/etc/init.d/*</file> initscripts is strongly
5616 recommended<footnote>
5617 In the future, the use of invoke-rc.d to invoke
5618 initscripts shall be made mandatory. Maintainers are
5619 advised to switch to invoke-rc.d as soon as
5621 </footnote>, instead of calling them directly.
5625 By default, <prgn>invoke-rc.d</prgn> will pass any
5626 action requests (start, stop, reload, restart...) to the
5627 <file>/etc/init.d</file> script, filtering out requests
5628 to start or restart a service out of its intended
5633 Most packages will simply need to change:
5634 <example compact="compact">/etc/init.d/<package>
5635 <action></example> in their <prgn>postinst</prgn>
5636 and <prgn>prerm</prgn> scripts to:
5637 <example compact="compact">
5638 if command -v invoke-rc.d >/dev/null 2>&1; then
5639 invoke-rc.d <var>package</var> <action>
5641 /etc/init.d/<var>package</var> <action>
5647 A package should register its initscript services using
5648 <prgn>update-rc.d</prgn> before it tries to invoke them
5649 using <prgn>invoke-rc.d</prgn>. Invocation of
5650 unregistered services may fail.
5654 For more information about using
5655 <prgn>invoke-rc.d</prgn>, please consult its man page
5656 <manref name="invoke-rc.d" section="8">.
5662 <heading>Boot-time initialization</heading>
5665 There used to be another directory, <file>/etc/rc.boot</file>,
5666 which contained scripts which were run once per machine
5667 boot. This has been deprecated in favour of links from
5668 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5669 described in <ref id="/etc/init.d">. Packages must not
5670 place files in <file>/etc/rc.boot</file>.
5675 <heading>Example</heading>
5678 The <prgn>bind</prgn> DNS (nameserver) package wants to
5679 make sure that the nameserver is running in multiuser
5680 runlevels, and is properly shut down with the system. It
5681 puts a script in <file>/etc/init.d</file>, naming the script
5682 appropriately <tt>bind</tt>. As you can see, the script
5683 interprets the argument <tt>reload</tt> to send the
5684 nameserver a <tt>HUP</tt> signal (causing it to reload its
5685 configuration); this way the system administrator can say
5686 <tt>/etc/init.d/bind reload</tt> to reload the name
5687 server. The script has one configurable value, which can
5688 be used to pass parameters to the named program at
5689 startup; this value is read from
5690 <file>/etc/default/bind</file> (see below).
5694 <example compact="compact">
5697 # Original version by Robert Leslie
5698 # <rob@mars.org>, edited by iwj and cs
5700 test -x /usr/sbin/named || exit 0
5702 # Source defaults file.
5704 if [ -f /etc/default/bind ]; then
5711 echo -n "Starting domain name service: named"
5712 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5717 echo -n "Stopping domain name service: named"
5718 start-stop-daemon --stop --quiet \
5719 --pidfile /var/run/named.pid --exec /usr/sbin/named
5723 echo -n "Restarting domain name service: named"
5724 start-stop-daemon --stop --quiet --oknodo \
5725 --pidfile /var/run/named.pid --exec /usr/sbin/named
5726 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5730 force-reload|reload)
5731 echo -n "Reloading configuration of domain name service: named"
5732 start-stop-daemon --stop --signal 1 --quiet \
5733 --pidfile /var/run/named.pid --exec /usr/sbin/named
5737 echo "Usage: /etc/init.d/bind " \
5738 " {start|stop|restart|reload|force-reload}" >&2
5748 Complementing the above init script is a configuration
5749 file <file>/etc/default/bind</file>, which contains
5750 configurable parameters used by the script. This would be
5751 created by the <prgn>postinst</prgn> script if it was not
5752 already present, and removed on purge by the
5753 <prgn>postrm</prgn> script.
5754 <example compact="compact">
5755 # Specified parameters to pass to named. See named(8).
5756 # You may uncomment the following line, and edit to taste.
5762 Another example on which you can base your
5763 <file>/etc/init.d</file> scripts is found in
5764 <file>/etc/init.d/skeleton</file>.
5768 If this package is happy with the default setup from
5769 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5770 and having named running in all runlevels, it can say in
5771 its <prgn>postinst</prgn>:
5772 <example compact="compact">
5773 update-rc.d bind defaults >/dev/null
5775 And in its <prgn>postrm</prgn>, to remove the links when the
5777 <example compact="compact">
5778 if [ "$1" = purge ]; then
5779 update-rc.d bind remove >/dev/null
5787 <heading>Console messages from <file>init.d</file> scripts</heading>
5790 This section describes the formats to be used for messages
5791 written to standard output by the <file>/etc/init.d</file>
5792 scripts. The intent is to improve the consistency of
5793 Debian's startup and shutdown look and feel. For this
5794 reason, please look very carefully at the details. We want
5795 the messages to have the same format in terms of wording,
5796 spaces, punctuation and case of letters.
5800 Here is a list of overall rules that you should use when you
5801 create output messages. They can be useful if you have a
5802 non-standard message that is not covered specifically in the
5809 Every message should fit in one line (fewer than 80
5810 characters), start with a capital letter and end with
5811 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5815 If you want to express that the computer is working on
5816 something (that is, performing a specific task, not
5817 starting or stopping a program), we use an "ellipsis"
5818 (three dots: <tt>...</tt>). Note that we don't insert
5819 spaces before or after the dots. If the task has been
5820 completed we write <tt>done.</tt> and a line feed.
5824 Design your messages as if the computer is telling you
5825 what it is doing (let it be polite :-), but don't
5826 mention "it" directly. For example, if you think of
5828 <example compact="compact">
5829 I'm starting network daemons: nfsd mountd.
5832 <example compact="compact">
5833 Starting network daemons: nfsd mountd.
5840 There are standard message formats for the following
5841 situations. They should be used by the <tt>init.d</tt>
5848 <p>When daemons are started</p>
5851 If your script starts one or more daemons, the output
5852 should look like this (a single line, no leading
5854 <example compact="compact">
5855 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5857 The <var>description</var> should describe the
5858 subsystem the daemon or set of daemons are part of,
5859 while <var>daemon-1</var> up to <var>daemon-n</var>
5860 denote each daemon's name (typically the file name of
5865 For example, the output of <file>/etc/init.d/lpd</file>
5867 <example compact="compact">
5868 Starting printer spooler: lpd.
5873 This can be achieved by saying
5874 <example compact="compact">
5875 echo -n "Starting printer spooler: lpd"
5876 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5879 in the script. If you have more than one daemon to
5880 start, you should do the following:
5881 <example compact="compact">
5882 echo -n "Starting remote file system services:"
5883 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5884 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5885 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5888 This makes it possible for the user to see what takes
5889 so long and when the final daemon has been started.
5890 You should be careful where to put spaces: in the
5891 example above the system administrator can easily
5892 comment out a line if they don't want to start a
5893 specific daemon, while the displayed message still
5899 <p>When a system parameter is being set</p>
5902 If you have to set up different system parameters
5903 during the system boot, you should use this format:
5904 <example compact="compact">
5905 Setting <var>parameter</var> to "<var>value</var>".
5910 You can use a statement such as the following to get
5912 <example compact="compact">
5913 echo "Setting DNS domainname to \"$domainname\"."
5918 Note that the same symbol (<tt>"</tt>) is used for the left
5919 and right quotation marks. A grave accent (<tt>`</tt>) is
5920 not a quote character; neither is an apostrophe
5926 <p>When a daemon is stopped or restarted</p>
5929 When you stop or restart a daemon, you should issue a
5930 message identical to the startup message, except that
5931 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5932 or <tt>Restarting</tt> respectively.
5936 For example, stopping the printer daemon will like
5938 <example compact="compact">
5939 Stopping printer spooler: lpd.
5945 <p>When something is executed</p>
5948 There are several examples where you have to run a
5949 program at system startup or shutdown to perform a
5950 specific task, for example, setting the system's clock
5951 using <prgn>netdate</prgn> or killing all processes
5952 when the system shuts down. Your message should look
5954 <example compact="compact">
5955 Doing something very useful...done.
5957 You should print the <tt>done.</tt> immediately after
5958 the job has been completed, so that the user is
5959 informed why they have to wait. You can get this
5961 <example compact="compact">
5962 echo -n "Doing something very useful..."
5971 <p>When the configuration is reloaded</p>
5974 When a daemon is forced to reload its configuration
5975 files you should use the following format:
5976 <example compact="compact">
5977 Reloading <var>description</var> configuration...done.
5979 where <var>description</var> is the same as in the
5980 daemon starting message.
5988 <heading>Cron jobs</heading>
5991 Packages must not modify the configuration file
5992 <file>/etc/crontab</file>, and they must not modify the files in
5993 <file>/var/spool/cron/crontabs</file>.</p>
5996 If a package wants to install a job that has to be executed
5997 via cron, it should place a file with the name of the
5998 package in one or more of the following directories:
5999 <example compact="compact">
6004 As these directory names imply, the files within them are
6005 executed on a daily, weekly, or monthly basis,
6006 respectively. The exact times are listed in
6007 <file>/etc/crontab</file>.</p>
6010 All files installed in any of these directories must be
6011 scripts (e.g., shell scripts or Perl scripts) so that they
6012 can easily be modified by the local system administrator.
6013 In addition, they should be treated as configuration
6018 If a certain job has to be executed more frequently than
6019 daily, the package should install a file
6020 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6021 same syntax as <file>/etc/crontab</file> and is processed by
6022 <prgn>cron</prgn> automatically. The file must also be
6023 treated as a configuration file. (Note that entries in the
6024 <file>/etc/cron.d</file> directory are not handled by
6025 <prgn>anacron</prgn>. Thus, you should only use this
6026 directory for jobs which may be skipped if the system is not
6030 The scripts or crontab entries in these directories should
6031 check if all necessary programs are installed before they
6032 try to execute them. Otherwise, problems will arise when a
6033 package was removed but not purged since configuration files
6034 are kept on the system in this situation.</p>
6038 <heading>Menus</heading>
6041 The Debian <tt>menu</tt> package provides a standard
6042 interface between packages providing applications and
6043 <em>menu programs</em> (either X window managers or
6044 text-based menu programs such as <prgn>pdmenu</prgn>).
6048 All packages that provide applications that need not be
6049 passed any special command line arguments for normal
6050 operation should register a menu entry for those
6051 applications, so that users of the <tt>menu</tt> package
6052 will automatically get menu entries in their window
6053 managers, as well in shells like <tt>pdmenu</tt>.
6057 Menu entries should follow the current menu policy.
6061 The menu policy can be found in the <tt>menu-policy</tt>
6062 files in the <tt>debian-policy</tt> package.
6063 It is also available from the Debian web mirrors at
6064 <tt><url name="/doc/packaging-manuals/menu-policy/"
6065 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6069 Please also refer to the <em>Debian Menu System</em>
6070 documentation that comes with the <package>menu</package>
6071 package for information about how to register your
6077 <heading>Multimedia handlers</heading>
6080 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6081 is a mechanism for encoding files and data streams and
6082 providing meta-information about them, in particular their
6083 type (e.g. audio or video) and format (e.g. PNG, HTML,
6088 Registration of MIME type handlers allows programs like mail
6089 user agents and web browsers to invoke these handlers to
6090 view, edit or display MIME types they don't support directly.
6094 Packages which provide the ability to view/show/play,
6095 compose, edit or print MIME types should register themselves
6096 as such following the current MIME support policy.
6100 The MIME support policy can be found in the <tt>mime-policy</tt>
6101 files in the <tt>debian-policy</tt> package.
6102 It is also available from the Debian web mirrors at
6103 <tt><url name="/doc/packaging-manuals/mime-policy/"
6104 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6110 <heading>Keyboard configuration</heading>
6113 To achieve a consistent keyboard configuration so that all
6114 applications interpret a keyboard event the same way, all
6115 programs in the Debian distribution must be configured to
6116 comply with the following guidelines.
6120 The following keys must have the specified interpretations:
6123 <tag><tt><--</tt></tag>
6124 <item>delete the character to the left of the cursor</item>
6126 <tag><tt>Delete</tt></tag>
6127 <item>delete the character to the right of the cursor</item>
6129 <tag><tt>Control+H</tt></tag>
6130 <item>emacs: the help prefix</item>
6133 The interpretation of any keyboard events should be
6134 independent of the terminal that is used, be it a virtual
6135 console, an X terminal emulator, an rlogin/telnet session,
6140 The following list explains how the different programs
6141 should be set up to achieve this:
6147 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6151 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6155 X translations are set up to make
6156 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6157 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6158 is the vt220 escape code for the "delete character"
6159 key). This must be done by loading the X resources
6160 using <prgn>xrdb</prgn> on all local X displays, not
6161 using the application defaults, so that the
6162 translation resources used correspond to the
6163 <prgn>xmodmap</prgn> settings.
6167 The Linux console is configured to make
6168 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6169 generate <tt>ESC [ 3 ~</tt>.
6173 X applications are configured so that <tt><</tt>
6174 deletes left, and <tt>Delete</tt> deletes right. Motif
6175 applications already work like this.
6179 Terminals should have <tt>stty erase ^?</tt> .
6183 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6184 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6185 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6189 Emacs is programmed to map <tt>KB_Backspace</tt> or
6190 the <tt>stty erase</tt> character to
6191 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6192 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6193 <tt>^H</tt> to <tt>help</tt> as always.
6197 Other applications use the <tt>stty erase</tt>
6198 character and <tt>kdch1</tt> for the two delete keys,
6199 with ASCII DEL being "delete previous character" and
6200 <tt>kdch1</tt> being "delete character under
6208 This will solve the problem except for the following
6215 Some terminals have a <tt><--</tt> key that cannot
6216 be made to produce anything except <tt>^H</tt>. On
6217 these terminals Emacs help will be unavailable on
6218 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6219 character takes precedence in Emacs, and has been set
6220 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6221 available) can be used instead.
6225 Some operating systems use <tt>^H</tt> for <tt>stty
6226 erase</tt>. However, modern telnet versions and all
6227 rlogin versions propagate <tt>stty</tt> settings, and
6228 almost all UNIX versions honour <tt>stty erase</tt>.
6229 Where the <tt>stty</tt> settings are not propagated
6230 correctly, things can be made to work by using
6231 <tt>stty</tt> manually.
6235 Some systems (including previous Debian versions) use
6236 <prgn>xmodmap</prgn> to arrange for both
6237 <tt><--</tt> and <tt>Delete</tt> to generate
6238 <tt>KB_Delete</tt>. We can change the behavior of
6239 their X clients using the same X resources that we use
6240 to do it for our own clients, or configure our clients
6241 using their resources when things are the other way
6242 around. On displays configured like this
6243 <tt>Delete</tt> will not work, but <tt><--</tt>
6248 Some operating systems have different <tt>kdch1</tt>
6249 settings in their <tt>terminfo</tt> database for
6250 <tt>xterm</tt> and others. On these systems the
6251 <tt>Delete</tt> key will not work correctly when you
6252 log in from a system conforming to our policy, but
6253 <tt><--</tt> will.
6260 <heading>Environment variables</heading>
6263 A program must not depend on environment variables to get
6264 reasonable defaults. (That's because these environment
6265 variables would have to be set in a system-wide
6266 configuration file like <file>/etc/profile</file>, which is not
6267 supported by all shells.)
6271 If a program usually depends on environment variables for its
6272 configuration, the program should be changed to fall back to
6273 a reasonable default configuration if these environment
6274 variables are not present. If this cannot be done easily
6275 (e.g., if the source code of a non-free program is not
6276 available), the program must be replaced by a small
6277 "wrapper" shell script which sets the environment variables
6278 if they are not already defined, and calls the original program.
6282 Here is an example of a wrapper script for this purpose:
6284 <example compact="compact">
6286 BAR=${BAR:-/var/lib/fubar}
6288 exec /usr/lib/foo/foo "$@"
6293 Furthermore, as <file>/etc/profile</file> is a configuration
6294 file of the <prgn>base-files</prgn> package, other packages must
6295 not put any environment variables or other commands into that
6300 <sect id="doc-base">
6301 <heading>Registering Documents using doc-base</heading>
6304 The <package>doc-base</package> package implements a
6305 flexible mechanism for handling and presenting
6306 documentation. The recommended practice is for every Debian
6307 package that provides online documentation (other than just
6308 manual pages) to register these documents with
6309 <package>doc-base</package> by installing a
6310 <package>doc-base</package> control file via the
6311 <prgn/install-docs/ script at installation time and
6312 de-register the manuals again when the package is removed.
6315 Please refer to the documentation that comes with the
6316 <package>doc-base</package> package for information and
6325 <heading>Files</heading>
6328 <heading>Binaries</heading>
6331 Two different packages must not install programs with
6332 different functionality but with the same filenames. (The
6333 case of two programs having the same functionality but
6334 different implementations is handled via "alternatives" or
6335 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6336 <ref id="conflicts"> respectively.) If this case happens,
6337 one of the programs must be renamed. The maintainers should
6338 report this to the <tt>debian-devel</tt> mailing list and
6339 try to find a consensus about which program will have to be
6340 renamed. If a consensus cannot be reached, <em>both</em>
6341 programs must be renamed.
6345 By default, when a package is being built, any binaries
6346 created should include debugging information, as well as
6347 being compiled with optimization. You should also turn on
6348 as many reasonable compilation warnings as possible; this
6349 makes life easier for porters, who can then look at build
6350 logs for possible problems. For the C programming language,
6351 this means the following compilation parameters should be
6353 <example compact="compact">
6355 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6357 install -s # (or use strip on the files in debian/tmp)
6362 Note that by default all installed binaries should be stripped,
6363 either by using the <tt>-s</tt> flag to
6364 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6365 the binaries after they have been copied into
6366 <file>debian/tmp</file> but before the tree is made into a
6371 Although binaries in the build tree should be compiled with
6372 debugging information by default, it can often be difficult
6373 to debug programs if they are also subjected to compiler
6374 optimization. For this reason, it is recommended to support
6375 the standardized environment
6376 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6377 contain several flags to change how a package is compiled
6385 The presence of this string means that the package
6386 should be compiled with a minimum of optimization.
6387 For C programs, it is best to add <tt>-O0</tt>
6388 to <tt>CFLAGS</tt> (although this is usually the
6389 default). Some programs might fail to build or run at
6390 this level of optimization; it may be necessary to
6391 use <tt>-O1</tt>, for example.
6395 This string means that the debugging symbols should
6396 not be stripped from the binary during installation,
6397 so that debugging information may be included in the package.
6403 The following makefile snippet is an example of how one may
6404 implement the build options; you will probably have to
6405 massage this example in order to make it work for your
6407 <example compact="compact">
6410 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6411 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6412 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6413 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6415 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6420 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6421 INSTALL_PROGRAM += -s
6427 It is up to the package maintainer to decide what
6428 compilation options are best for the package. Certain
6429 binaries (such as computationally-intensive programs) will
6430 function better with certain flags (<tt>-O3</tt>, for
6431 example); feel free to use them. Please use good judgment
6432 here. Don't use flags for the sake of it; only use them
6433 if there is good reason to do so. Feel free to override
6434 the upstream author's ideas about which compilation
6435 options are best: they are often inappropriate for our
6441 <sect id="libraries">
6442 <heading>Libraries</heading>
6445 The shared version of a library must be compiled with
6446 <tt>-fPIC</tt>, and the static version must not be. In other
6447 words, each source unit (<tt>*.c</tt>, for example, for C files)
6448 will need to be compiled twice.
6452 You must specify the gcc option <tt>-D_REENTRANT</tt>
6453 when building a library (either static or shared) to make
6454 the library compatible with LinuxThreads.
6458 Although not enforced by the build tools, shared libraries
6459 must be linked against all libraries that they use symbols from
6460 in the same way that binaries are. This ensures the correct
6461 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6462 system and guarantees that all libraries can be safely opened
6463 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6464 option <tt>-Wl,-z,defs</tt> when building a shared library.
6465 Since this option enforces symbol resolution at build time,
6466 a missing library reference will be caught early as a fatal
6471 All installed shared libraries should be stripped with
6472 <example compact="compact">
6473 strip --strip-unneeded <var>your-lib</var>
6475 (The option <tt>--strip-unneeded</tt> makes
6476 <prgn>strip</prgn> remove only the symbols which aren't
6477 needed for relocation processing.) Shared libraries can
6478 function perfectly well when stripped, since the symbols for
6479 dynamic linking are in a separate part of the ELF object
6481 You might also want to use the options
6482 <tt>--remove-section=.comment</tt> and
6483 <tt>--remove-section=.note</tt> on both shared libraries
6484 and executables, and <tt>--strip-debug</tt> on static
6490 Note that under some circumstances it may be useful to
6491 install a shared library unstripped, for example when
6492 building a separate package to support debugging.
6496 Shared object files (often <file>.so</file> files) that are not
6497 public libraries, that is, they are not meant to be linked
6498 to by third party executables (binaries of other packages),
6499 should be installed in subdirectories of the
6500 <file>/usr/lib</file> directory. Such files are exempt from the
6501 rules that govern ordinary shared libraries, except that
6502 they must not be installed executable and should be
6504 A common example are the so-called "plug-ins",
6505 internal shared objects that are dynamically loaded by
6506 programs using <manref name="dlopen" section="3">.
6511 Packages containing shared libraries that may be linked to
6512 by other packages' binaries, but which for some
6513 <em>compelling</em> reason can not be installed in
6514 <file>/usr/lib</file> directory, may install the shared library
6515 files in subdirectories of the <file>/usr/lib</file> directory,
6516 in which case they should arrange to add that directory in
6517 <file>/etc/ld.so.conf</file> in the package's post-installation
6518 script, and remove it in the package's post-removal script.
6522 An ever increasing number of packages are using
6523 <prgn>libtool</prgn> to do their linking. The latest GNU
6524 libtools (>= 1.3a) can take advantage of the metadata in the
6525 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6526 files). The main advantage of <prgn>libtool</prgn>'s
6527 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6528 store and subsequently access metadata with respect to the
6529 libraries it builds. <prgn>libtool</prgn> will search for
6530 those files, which contain a lot of useful information about
6531 a library (such as library dependency information for static
6532 linking). Also, they're <em>essential</em> for programs
6533 using <tt>libltdl</tt>.<footnote>
6534 Although <prgn>libtool</prgn> is fully capable of
6535 linking against shared libraries which don't have
6536 <tt>.la</tt> files, as it is a mere shell script it can
6537 add considerably to the build time of a
6538 <prgn>libtool</prgn>-using package if that shell script
6539 has to derive all this information from first principles
6540 for each library every time it is linked. With the
6541 advent of <prgn>libtool</prgn> version 1.4 (and to a
6542 lesser extent <prgn>libtool</prgn> version 1.3), the
6543 <file>.la</file> files also store information about
6544 inter-library dependencies which cannot necessarily be
6545 derived after the <file>.la</file> file is deleted.
6550 Packages that use <prgn>libtool</prgn> to create shared
6551 libraries should include the <file>.la</file> files in the
6552 <tt>-dev</tt> package, unless the package relies on
6553 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6554 the <tt>.la</tt> files must go in the run-time library
6559 You must make sure that you use only released versions of
6560 shared libraries to build your packages; otherwise other
6561 users will not be able to run your binaries
6562 properly. Producing source packages that depend on
6563 unreleased compilers is also usually a bad
6570 <heading>Shared libraries</heading>
6572 This section has moved to <ref id="sharedlibs">.
6578 <heading>Scripts</heading>
6581 All command scripts, including the package maintainer
6582 scripts inside the package and used by <prgn>dpkg</prgn>,
6583 should have a <tt>#!</tt> line naming the shell to be used
6588 In the case of Perl scripts this should be
6589 <tt>#!/usr/bin/perl</tt>.
6593 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6594 should almost certainly start with <tt>set -e</tt> so that
6595 errors are detected. Every script should use
6596 <tt>set -e</tt> or check the exit status of <em>every</em>
6601 The standard shell interpreter <file>/bin/sh</file> can be a
6602 symbolic link to any POSIX compatible shell, if <tt>echo
6603 -n</tt> does not generate a newline.<footnote>
6604 Debian policy specifies POSIX behavior for
6605 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6606 use in the Linux community (in particular including this
6607 policy, the Linux kernel source, many Debian scripts,
6608 etc.). This <tt>echo -n</tt> mechanism is valid but not
6609 required under POSIX, hence this explicit addition.
6610 Also, rumour has it that this shall be mandated under
6613 Thus, shell scripts specifying <file>/bin/sh</file> as
6614 interpreter should only use POSIX features. If a script
6615 requires non-POSIX features from the shell interpreter, the
6616 appropriate shell must be specified in the first line of the
6617 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6618 depend on the package providing the shell (unless the shell
6619 package is marked "Essential", as in the case of
6624 You may wish to restrict your script to POSIX features when
6625 possible so that it may use <file>/bin/sh</file> as its
6626 interpreter. If your script works with <prgn>dash</prgn>
6627 (originally called <prgn>ash</prgn>), it's probably POSIX
6628 compliant, but if you are in doubt, use
6629 <file>/bin/bash</file>.
6633 Perl scripts should check for errors when making any
6634 system calls, including <tt>open</tt>, <tt>print</tt>,
6635 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6639 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6640 scripting languages. See <em>Csh Programming Considered
6641 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6642 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
6643 If an upstream package comes with <prgn>csh</prgn> scripts
6644 then you must make sure that they start with
6645 <tt>#!/bin/csh</tt> and make your package depend on the
6646 <prgn>c-shell</prgn> virtual package.
6650 Any scripts which create files in world-writeable
6651 directories (e.g., in <file>/tmp</file>) must use a
6652 mechanism which will fail if a file with the same name
6657 The Debian base system provides the <prgn>tempfile</prgn>
6658 and <prgn>mktemp</prgn> utilities for use by scripts for
6665 <heading>Symbolic links</heading>
6668 In general, symbolic links within a top-level directory
6669 should be relative, and symbolic links pointing from one
6670 top-level directory into another should be absolute. (A
6671 top-level directory is a sub-directory of the root
6672 directory <file>/</file>.)
6676 In addition, symbolic links should be specified as short as
6677 possible, i.e., link targets like <file>foo/../bar</file> are
6682 Note that when creating a relative link using
6683 <prgn>ln</prgn> it is not necessary for the target of the
6684 link to exist relative to the working directory you're
6685 running <prgn>ln</prgn> from, nor is it necessary to change
6686 directory to the directory where the link is to be made.
6687 Simply include the string that should appear as the target
6688 of the link (this will be a pathname relative to the
6689 directory in which the link resides) as the first argument
6694 For example, in your <prgn>Makefile</prgn> or
6695 <file>debian/rules</file>, you can do things like:
6696 <example compact="compact">
6697 ln -fs gcc $(prefix)/bin/cc
6698 ln -fs gcc debian/tmp/usr/bin/cc
6699 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6700 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6705 A symbolic link pointing to a compressed file should always
6706 have the same file extension as the referenced file. (For
6707 example, if a file <file>foo.gz</file> is referenced by a
6708 symbolic link, the filename of the link has to end with
6709 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6714 <heading>Device files</heading>
6717 Packages must not include device files in the package file
6722 If a package needs any special device files that are not
6723 included in the base system, it must call
6724 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6725 after notifying the user<footnote>
6726 This notification could be done via a (low-priority)
6727 debconf message, or an echo (printf) statement.
6732 Packages must not remove any device files in the
6733 <prgn>postrm</prgn> or any other script. This is left to the
6734 system administrator.
6738 Debian uses the serial devices
6739 <file>/dev/ttyS*</file>. Programs using the old
6740 <file>/dev/cu*</file> devices should be changed to use
6741 <file>/dev/ttyS*</file>.
6745 <sect id="config-files">
6746 <heading>Configuration files</heading>
6749 <heading>Definitions</heading>
6753 <tag>configuration file</tag>
6755 A file that affects the operation of a program, or
6756 provides site- or host-specific information, or
6757 otherwise customizes the behavior of a program.
6758 Typically, configuration files are intended to be
6759 modified by the system administrator (if needed or
6760 desired) to conform to local policy or to provide
6761 more useful site-specific behavior.
6764 <tag><tt>conffile</tt></tag>
6766 A file listed in a package's <tt>conffiles</tt>
6767 file, and is treated specially by <prgn>dpkg</prgn>
6768 (see <ref id="configdetails">).
6774 The distinction between these two is important; they are
6775 not interchangeable concepts. Almost all
6776 <tt>conffile</tt>s are configuration files, but many
6777 configuration files are not <tt>conffiles</tt>.
6781 Note that a script that embeds configuration information
6782 (such as most of the files in <file>/etc/default</file> and
6783 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6784 configuration file and should be treated as such.
6789 <heading>Location</heading>
6792 Any configuration files created or used by your package
6793 must reside in <file>/etc</file>. If there are several,
6794 consider creating a subdirectory of <file>/etc</file>
6795 named after your package.
6799 If your package creates or uses configuration files
6800 outside of <file>/etc</file>, and it is not feasible to modify
6801 the package to use <file>/etc</file> directly, put the files
6802 in <file>/etc</file> and create symbolic links to those files
6803 from the location that the package requires.
6808 <heading>Behavior</heading>
6811 Configuration file handling must conform to the following
6813 <list compact="compact">
6815 local changes must be preserved during a package
6819 configuration files must be preserved when the
6820 package is removed, and only deleted when the
6827 The easy way to achieve this behavior is to make the
6828 configuration file a <tt>conffile</tt>. This is
6829 appropriate only if it is possible to distribute a default
6830 version that will work for most installations, although
6831 some system administrators may choose to modify it. This
6832 implies that the default version will be part of the
6833 package distribution, and must not be modified by the
6834 maintainer scripts during installation (or at any other
6839 In order to ensure that local changes are preserved
6840 correctly, no package may contain or make hard links to
6841 conffiles.<footnote>
6842 Rationale: There are two problems with hard links.
6843 The first is that some editors break the link while
6844 editing one of the files, so that the two files may
6845 unwittingly become unlinked and different. The second
6846 is that <prgn>dpkg</prgn> might break the hard link
6847 while upgrading <tt>conffile</tt>s.
6852 The other way to do it is via the maintainer scripts. In
6853 this case, the configuration file must not be listed as a
6854 <tt>conffile</tt> and must not be part of the package
6855 distribution. If the existence of a file is required for
6856 the package to be sensibly configured it is the
6857 responsibility of the package maintainer to provide
6858 maintainer scripts which correctly create, update and
6859 maintain the file and remove it on purge. (See <ref
6860 id="maintainerscripts"> for more information.) These
6861 scripts must be idempotent (i.e., must work correctly if
6862 <prgn>dpkg</prgn> needs to re-run them due to errors
6863 during installation or removal), must cope with all the
6864 variety of ways <prgn>dpkg</prgn> can call maintainer
6865 scripts, must not overwrite or otherwise mangle the user's
6866 configuration without asking, must not ask unnecessary
6867 questions (particularly during upgrades), and otherwise be
6872 The scripts are not required to configure every possible
6873 option for the package, but only those necessary to get
6874 the package running on a given system. Ideally the
6875 sysadmin should not have to do any configuration other
6876 than that done (semi-)automatically by the
6877 <prgn>postinst</prgn> script.
6881 A common practice is to create a script called
6882 <file><var>package</var>-configure</file> and have the
6883 package's <prgn>postinst</prgn> call it if and only if the
6884 configuration file does not already exist. In certain
6885 cases it is useful for there to be an example or template
6886 file which the maintainer scripts use. Such files should
6887 be in <file>/usr/share/<var>package</var></file> or
6888 <file>/usr/lib/<var>package</var></file> (depending on whether
6889 they are architecture-independent or not). There should
6890 be symbolic links to them from
6891 <file>/usr/share/doc/<var>package</var>/examples</file> if
6892 they are examples, and should be perfectly ordinary
6893 <prgn>dpkg</prgn>-handled files (<em>not</em>
6894 configuration files).
6898 These two styles of configuration file handling must
6899 not be mixed, for that way lies madness:
6900 <prgn>dpkg</prgn> will ask about overwriting the file
6901 every time the package is upgraded.
6906 <heading>Sharing configuration files</heading>
6909 Packages which specify the same file as a
6910 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6911 with each other. (This is an instance of the general rule
6912 about not sharing files. Note that neither alternatives
6913 nor diversions are likely to be appropriate in this case;
6914 in particular, <prgn>dpkg</prgn> does not handle diverted
6915 <tt>conffile</tt>s well.)
6919 The maintainer scripts must not alter a <tt>conffile</tt>
6920 of <em>any</em> package, including the one the scripts
6925 If two or more packages use the same configuration file
6926 and it is reasonable for both to be installed at the same
6927 time, one of these packages must be defined as
6928 <em>owner</em> of the configuration file, i.e., it will be
6929 the package which handles that file as a configuration
6930 file. Other packages that use the configuration file must
6931 depend on the owning package if they require the
6932 configuration file to operate. If the other package will
6933 use the configuration file if present, but is capable of
6934 operating without it, no dependency need be declared.
6938 If it is desirable for two or more related packages to
6939 share a configuration file <em>and</em> for all of the
6940 related packages to be able to modify that configuration
6941 file, then the following should be done:
6942 <enumlist compact="compact">
6944 One of the related packages (the "owning" package)
6945 will manage the configuration file with maintainer
6946 scripts as described in the previous section.
6949 The owning package should also provide a program
6950 that the other packages may use to modify the
6954 The related packages must use the provided program
6955 to make any desired modifications to the
6956 configuration file. They should either depend on
6957 the core package to guarantee that the configuration
6958 modifier program is available or accept gracefully
6959 that they cannot modify the configuration file if it
6960 is not. (This is in addition to the fact that the
6961 configuration file may not even be present in the
6968 Sometimes it's appropriate to create a new package which
6969 provides the basic infrastructure for the other packages
6970 and which manages the shared configuration files. (The
6971 <tt>sgml-base</tt> package is a good example.)
6976 <heading>User configuration files ("dotfiles")</heading>
6979 The files in <file>/etc/skel</file> will automatically be
6980 copied into new user accounts by <prgn>adduser</prgn>.
6981 No other program should reference the files in
6982 <file>/etc/skel</file>.
6986 Therefore, if a program needs a dotfile to exist in
6987 advance in <file>$HOME</file> to work sensibly, that dotfile
6988 should be installed in <file>/etc/skel</file> and treated as a
6993 However, programs that require dotfiles in order to
6994 operate sensibly are a bad thing, unless they do create
6995 the dotfiles themselves automatically.
6999 Furthermore, programs should be configured by the Debian
7000 default installation to behave as closely to the upstream
7001 default behaviour as possible.
7005 Therefore, if a program in a Debian package needs to be
7006 configured in some way in order to operate sensibly, that
7007 should be done using a site-wide configuration file placed
7008 in <file>/etc</file>. Only if the program doesn't support a
7009 site-wide default configuration and the package maintainer
7010 doesn't have time to add it may a default per-user file be
7011 placed in <file>/etc/skel</file>.
7015 <file>/etc/skel</file> should be as empty as we can make it.
7016 This is particularly true because there is no easy (or
7017 necessarily desirable) mechanism for ensuring that the
7018 appropriate dotfiles are copied into the accounts of
7019 existing users when a package is installed.
7025 <heading>Log files</heading>
7027 Log files should usually be named
7028 <file>/var/log/<var>package</var>.log</file>. If you have many
7029 log files, or need a separate directory for permission
7030 reasons (<file>/var/log</file> is writable only by
7031 <file>root</file>), you should usually create a directory named
7032 <file>/var/log/<var>package</var></file> and place your log
7037 Log files must be rotated occasionally so that they don't
7038 grow indefinitely; the best way to do this is to drop a log
7039 rotation configuration file into the directory
7040 <file>/etc/logrotate.d</file> and use the facilities provided by
7041 logrotate.<footnote>
7043 The traditional approach to log files has been to set up
7044 <em>ad hoc</em> log rotation schemes using simple shell
7045 scripts and cron. While this approach is highly
7046 customizable, it requires quite a lot of sysadmin work.
7047 Even though the original Debian system helped a little
7048 by automatically installing a system which can be used
7049 as a template, this was deemed not enough.
7053 The use of <prgn>logrotate</prgn>, a program developed
7054 by Red Hat, is better, as it centralizes log management.
7055 It has both a configuration file
7056 (<file>/etc/logrotate.conf</file>) and a directory where
7057 packages can drop their individual log rotation
7058 configurations (<file>/etc/logrotate.d</file>).
7061 Here is a good example for a logrotate config
7062 file (for more information see <manref name="logrotate"
7064 <example compact="compact">
7065 /var/log/foo/*.log {
7070 /etc/init.d/foo force-reload
7074 This rotates all files under <file>/var/log/foo</file>, saves 12
7075 compressed generations, and forces the daemon to reload its
7076 configuration information after the log rotation.
7080 Log files should be removed when the package is
7081 purged (but not when it is only removed). This should be
7082 done by the <prgn>postrm</prgn> script when it is called
7083 with the argument <tt>purge</tt> (see <ref
7084 id="removedetails">).
7089 <heading>Permissions and owners</heading>
7092 The rules in this section are guidelines for general use.
7093 If necessary you may deviate from the details below.
7094 However, if you do so you must make sure that what is done
7095 is secure and you should try to be as consistent as possible
7096 with the rest of the system. You should probably also
7097 discuss it on <prgn>debian-devel</prgn> first.
7101 Files should be owned by <tt>root.root</tt>, and made
7102 writable only by the owner and universally readable (and
7103 executable, if appropriate), that is mode 644 or 755.
7107 Directories should be mode 755 or (for group-writability)
7108 mode 2775. The ownership of the directory should be
7109 consistent with its mode: if a directory is mode 2775, it
7110 should be owned by the group that needs write access to
7115 Setuid and setgid executables should be mode 4755 or 2755
7116 respectively, and owned by the appropriate user or group.
7117 They should not be made unreadable (modes like 4711 or
7118 2711 or even 4111); doing so achieves no extra security,
7119 because anyone can find the binary in the freely available
7120 Debian package; it is merely inconvenient. For the same
7121 reason you should not restrict read or execute permissions
7122 on non-set-id executables.
7126 Some setuid programs need to be restricted to particular
7127 sets of users, using file permissions. In this case they
7128 should be owned by the uid to which they are set-id, and by
7129 the group which should be allowed to execute them. They
7130 should have mode 4754; again there is no point in making
7131 them unreadable to those users who must not be allowed to
7136 It is possible to arrange that the system administrator can
7137 reconfigure the package to correspond to their local
7138 security policy by changing the permissions on a binary:
7139 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7140 described below.<footnote>
7141 Ordinary files installed by <prgn>dpkg</prgn> (as
7142 opposed to <tt>conffile</tt>s and other similar objects)
7143 normally have their permissions reset to the distributed
7144 permissions when the package is reinstalled. However,
7145 the use of <prgn>dpkg-statoverride</prgn> overrides this
7146 default behaviour. If you use this method, you should
7147 remember to describe <prgn>dpkg-statoverride</prgn> in
7148 the package documentation; being a relatively new
7149 addition to Debian, it is probably not yet well-known.
7151 Another method you should consider is to create a group for
7152 people allowed to use the program(s) and make any setuid
7153 executables executable only by that group.
7157 If you need to create a new user or group for your package
7158 there are two possibilities. Firstly, you may need to
7159 make some files in the binary package be owned by this
7160 user or group, or you may need to compile the user or
7161 group id (rather than just the name) into the binary
7162 (though this latter should be avoided if possible, as in
7163 this case you need a statically allocated id).</p>
7166 If you need a statically allocated id, you must ask for a
7167 user or group id from the <tt>base-passwd</tt> maintainer,
7168 and must not release the package until you have been
7169 allocated one. Once you have been allocated one you must
7170 either make the package depend on a version of the
7171 <tt>base-passwd</tt> package with the id present in
7172 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7173 your package to create the user or group itself with the
7174 correct id (using <tt>adduser</tt>) in its
7175 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7176 the <prgn>postinst</prgn> is to be preferred if it is
7177 possible, otherwise a pre-dependency will be needed on the
7178 <tt>adduser</tt> package.)
7182 On the other hand, the program might be able to determine
7183 the uid or gid from the user or group name at runtime, so
7184 that a dynamically allocated id can be used. In this case
7185 you should choose an appropriate user or group name,
7186 discussing this on <prgn>debian-devel</prgn> and checking
7187 with the <package/base-passwd/ maintainer that it is unique and that
7188 they do not wish you to use a statically allocated id
7189 instead. When this has been checked you must arrange for
7190 your package to create the user or group if necessary using
7191 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7192 <prgn>postinst</prgn> script (again, the latter is to be
7193 preferred if it is possible).
7197 Note that changing the numeric value of an id associated
7198 with a name is very difficult, and involves searching the
7199 file system for all appropriate files. You need to think
7200 carefully whether a static or dynamic id is required, since
7201 changing your mind later will cause problems.
7204 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7206 This section is not intended as policy, but as a
7207 description of the use of <prgn>dpkg-statoverride</prgn>.
7211 <prgn>dpkg-statoverride</prgn> is a replacement for the
7212 deprecated <tt>suidmanager</tt> package. Packages which
7213 previously used <tt>suidmanager</tt> should have a
7214 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7215 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7216 and <tt>suidunregister</tt> should now be simply removed
7217 from the maintainer scripts.
7221 If a system administrator wishes to have a file (or
7222 directory or other such thing) installed with owner and
7223 permissions different from those in the distributed Debian
7224 package, they can use the <prgn>dpkg-statoverride</prgn>
7225 program to instruct <prgn>dpkg</prgn> to use the different
7226 settings every time the file is installed. Thus the
7227 package maintainer should distribute the files with their
7228 normal permissions, and leave it for the system
7229 administrator to make any desired changes. For example, a
7230 daemon which is normally required to be setuid root, but
7231 in certain situations could be used without being setuid,
7232 should be installed setuid in the <tt>.deb</tt>. Then the
7233 local system administrator can change this if they wish.
7234 If there are two standard ways of doing it, the package
7235 maintainer can use <tt>debconf</tt> to find out the
7236 preference, and call <prgn>dpkg-statoverride</prgn> in the
7237 maintainer script if necessary to accommodate the system
7238 administrator's choice.
7242 Given the above, <prgn>dpkg-statoverride</prgn> is
7243 essentially a tool for system administrators and would not
7244 normally be needed in the maintainer scripts. There is
7245 one type of situation, though, where calls to
7246 <prgn>dpkg-statoverride</prgn> would be needed in the
7247 maintainer scripts, and that involves packages which use
7248 dynamically allocated user or group ids. In such a
7249 situation, something like the following idiom can be very
7250 helpful in the package's <prgn>postinst</prgn>, where
7251 <tt>sysuser</tt> is a dynamically allocated id:
7253 for i in /usr/bin/foo /usr/sbin/bar
7255 if ! dpkg-statoverride --list $i >/dev/null
7257 dpkg-statoverride --update --add sysuser root 4755 $i
7261 The corresponding <tt>dpkg-statoverride --remove</tt>
7262 calls can then be made unconditionally when the package is
7270 <chapt id="customized-programs">
7271 <heading>Customized programs</heading>
7273 <sect id="arch-spec">
7274 <heading>Architecture specification strings</heading>
7277 If a program needs to specify an <em>architecture specification
7278 string</em> in some place, the following format should be
7279 used: <var>arch</var>-<var>os</var><footnote>
7280 The following architectures and operating systems are
7281 currently recognised by <prgn>dpkg-architecture</prgn>.
7282 The architecture, <tt><var>arch</var></tt>, is one of
7283 the following: <tt>alpha</tt>, <tt>arm</tt>,
7284 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7285 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7286 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7287 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7288 operating system, <tt><var>os</var></tt>, is one of:
7289 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7290 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7291 reserved for the GNU/Hurd operating system.
7296 Note that we don't want to use
7297 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7298 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7299 since this would make our programs incompatible with other
7300 Linux distributions. We also don't use something like
7301 <tt><var>arch</var>-unknown-linux</tt>, since the
7302 <tt>unknown</tt> does not look very good.
7307 <heading>Daemons</heading>
7310 The configuration files <file>/etc/services</file>,
7311 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7312 by the <prgn>netbase</prgn> package and must not be modified
7317 If a package requires a new entry in one of these files, the
7318 maintainer should get in contact with the
7319 <prgn>netbase</prgn> maintainer, who will add the entries
7320 and release a new version of the <prgn>netbase</prgn>
7325 The configuration file <file>/etc/inetd.conf</file> must not be
7326 modified by the package's scripts except via the
7327 <prgn>update-inetd</prgn> script or the
7328 <file>DebianNet.pm</file> Perl module. See their documentation
7329 for details on how to add entries.
7333 If a package wants to install an example entry into
7334 <file>/etc/inetd.conf</file>, the entry must be preceded with
7335 exactly one hash character (<tt>#</tt>). Such lines are
7336 treated as "commented out by user" by the
7337 <prgn>update-inetd</prgn> script and are not changed or
7338 activated during package updates.
7343 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7347 Some programs need to create pseudo-ttys. This should be done
7348 using Unix98 ptys if the C library supports it. The resulting
7349 program must not be installed setuid root, unless that
7350 is required for other functionality.
7354 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7355 <file>/var/log/lastlog</file> must be installed writeable by
7356 group <tt>utmp</tt>. Programs which need to modify those
7357 files must be installed setgid <tt>utmp</tt>.
7362 <heading>Editors and pagers</heading>
7365 Some programs have the ability to launch an editor or pager
7366 program to edit or display a text document. Since there are
7367 lots of different editors and pagers available in the Debian
7368 distribution, the system administrator and each user should
7369 have the possibility to choose their preferred editor and
7374 In addition, every program should choose a good default
7375 editor/pager if none is selected by the user or system
7380 Thus, every program that launches an editor or pager must
7381 use the EDITOR or PAGER environment variable to determine
7382 the editor or pager the user wishes to use. If these
7383 variables are not set, the programs <file>/usr/bin/editor</file>
7384 and <file>/usr/bin/pager</file> should be used, respectively.
7388 These two files are managed through the <prgn>dpkg</prgn>
7389 "alternatives" mechanism. Thus every package providing an
7390 editor or pager must call the
7391 <prgn>update-alternatives</prgn> script to register these
7396 If it is very hard to adapt a program to make use of the
7397 EDITOR or PAGER variables, that program may be configured to
7398 use <file>/usr/bin/sensible-editor</file> and
7399 <file>/usr/bin/sensible-pager</file> as the editor or pager
7400 program respectively. These are two scripts provided in the
7401 Debian base system that check the EDITOR and PAGER variables
7402 and launch the appropriate program, and fall back to
7403 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7404 variable is not set.
7408 A program may also use the VISUAL environment variable to
7409 determine the user's choice of editor. If it exists, it
7410 should take precedence over EDITOR. This is in fact what
7411 <file>/usr/bin/sensible-editor</file> does.
7415 It is not required for a package to depend on
7416 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7417 package to provide such virtual packages.<footnote>
7418 The Debian base system already provides an editor and a
7424 <sect id="web-appl">
7425 <heading>Web servers and applications</heading>
7428 This section describes the locations and URLs that should
7429 be used by all web servers and web applications in the
7436 Cgi-bin executable files are installed in the
7438 <example compact="compact">
7439 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7441 and should be referred to as
7442 <example compact="compact">
7443 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7448 <p>Access to HTML documents</p>
7451 HTML documents for a package are stored in
7452 <file>/usr/share/doc/<var>package</var></file>
7453 and can be referred to as
7454 <example compact="compact">
7455 http://localhost/doc/<var>package</var>/<var>filename</var>
7460 The web server should restrict access to the document
7461 tree so that only clients on the same host can read
7462 the documents. If the web server does not support such
7463 access controls, then it should not provide access at
7464 all, or ask about providing access during installation.
7469 <p>Web Document Root</p>
7472 Web Applications should try to avoid storing files in
7473 the Web Document Root. Instead they should use the
7474 /usr/share/doc/<var>package</var> directory for
7475 documents and register the Web Application via the
7476 <package>doc-base</package> package. If access to the
7477 web document root is unavoidable then use
7478 <example compact="compact">
7481 as the Document Root. This might be just a symbolic
7482 link to the location where the system administrator
7483 has put the real document root.
7491 <sect id="mail-transport-agents">
7492 <heading>Mail transport, delivery and user agents</heading>
7495 Debian packages which process electronic mail, whether mail
7496 user agents (MUAs) or mail transport agents (MTAs), must
7497 ensure that they are compatible with the configuration
7498 decisions below. Failure to do this may result in lost
7499 mail, broken <tt>From:</tt> lines, and other serious brain
7504 The mail spool is <file>/var/mail</file> and the interface to
7505 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7506 the FHS). On older systems, the mail spool may be
7507 physically located in <file>/var/spool/mail</file>, but all
7508 access to the mail spool should be via the
7509 <file>/var/mail</file> symlink. The mail spool is part of the
7510 base system and not part of the MTA package.
7514 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7515 programs (such as IMAP daemons) must lock the mailbox in an
7516 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7517 be combined with dot locking. To avoid deadlocks, a program
7518 should use <tt>fcntl()</tt> first and dot locking after
7519 this, or alternatively implement the two locking methods in
7520 a non blocking way<footnote>
7521 If it is not possible to establish both locks, the
7522 system shouldn't wait for the second lock to be
7523 established, but remove the first lock, wait a (random)
7524 time, and start over locking again.
7525 </footnote>. Using the functions <tt>maillock</tt> and
7526 <tt>mailunlock</tt> provided by the
7527 <tt>liblockfile*</tt><footnote>
7528 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7529 to use these functions.
7530 </footnote> packages is the recommended way to realize this.
7534 Mailboxes are generally mode 660
7535 <tt><var>user</var>.mail</tt> unless the system
7536 administrator has chosen otherwise. A MUA may remove a
7537 mailbox (unless it has nonstandard permissions) in which
7538 case the MTA or another MUA must recreate it if needed.
7539 Mailboxes must be writable by group mail.
7543 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7544 be setgid mail to do the locking mentioned above (and
7545 must obviously avoid accessing other users' mailboxes
7546 using this privilege).</p>
7549 <file>/etc/aliases</file> is the source file for the system mail
7550 aliases (e.g., postmaster, usenet, etc.), it is the one
7551 which the sysadmin and <prgn>postinst</prgn> scripts may
7552 edit. After <file>/etc/aliases</file> is edited the program or
7553 human editing it must call <prgn>newaliases</prgn>. All MTA
7554 packages must come with a <prgn>newaliases</prgn> program,
7555 even if it does nothing, but older MTA packages did not do
7556 this so programs should not fail if <prgn>newaliases</prgn>
7557 cannot be found. Note that because of this, all MTA
7558 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7559 <tt>Replaces: mail-transport-agent</tt> control file
7564 The convention of writing <tt>forward to
7565 <var>address</var></tt> in the mailbox itself is not
7566 supported. Use a <tt>.forward</tt> file instead.</p>
7569 The <prgn>rmail</prgn> program used by UUCP
7570 for incoming mail should be <file>/usr/sbin/rmail</file>.
7571 Likewise, <prgn>rsmtp</prgn>, for receiving
7572 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7576 If your package needs to know what hostname to use on (for
7577 example) outgoing news and mail messages which are generated
7578 locally, you should use the file <file>/etc/mailname</file>. It
7579 will contain the portion after the username and <tt>@</tt>
7580 (at) sign for email addresses of users on the machine
7581 (followed by a newline).
7585 Such package should check for the existence of this file
7586 when it is being configured. If it exists, it should be
7587 used without comment, although an MTA's configuration script
7588 may wish to prompt the user even if it finds that this file
7589 exists. If the file does not exist, the package should
7590 prompt the user for the value (preferably using
7591 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7592 as well as using it in the package's configuration. The
7593 prompt should make it clear that the name will not just be
7594 used by that package. For example, in this situation the
7595 <tt>inn</tt> package could say something like:
7596 <example compact="compact">
7597 Please enter the "mail name" of your system. This is the
7598 hostname portion of the address to be shown on outgoing
7599 news and mail messages. The default is
7600 <var>syshostname</var>, your system's host name. Mail
7601 name ["<var>syshostname</var>"]:
7603 where <var>syshostname</var> is the output of <tt>hostname
7609 <heading>News system configuration</heading>
7612 All the configuration files related to the NNTP (news)
7613 servers and clients should be located under
7614 <file>/etc/news</file>.</p>
7617 There are some configuration issues that apply to a number
7618 of news clients and server packages on the machine. These
7622 <tag><file>/etc/news/organization</file></tag>
7624 A string which should appear as the
7625 organization header for all messages posted
7626 by NNTP clients on the machine
7629 <tag><file>/etc/news/server</file></tag>
7631 Contains the FQDN of the upstream NNTP
7632 server, or localhost if the local machine is
7637 Other global files may be added as required for cross-package news
7644 <heading>Programs for the X Window System</heading>
7647 <heading>Providing X support and package priorities</heading>
7650 Programs that can be configured with support for the X
7651 Window System must be configured to do so and must declare
7652 any package dependencies necessary to satisfy their
7653 runtime requirements when using the X Window System. If
7654 such a package is of higher priority than the X packages
7655 on which it depends, it is required that either the
7656 X-specific components be split into a separate package, or
7657 that an alternative version of the package, which includes
7658 X support, be provided, or that the package's priority be
7664 <heading>Packages providing an X server</heading>
7667 Packages that provide an X server that, directly or
7668 indirectly, communicates with real input and display
7669 hardware should declare in their control data that they
7670 provide the virtual package <tt>xserver</tt>.<footnote>
7671 This implements current practice, and provides an
7672 actual policy for usage of the <tt>xserver</tt>
7673 virtual package which appears in the virtual packages
7674 list. In a nutshell, X servers that interface
7675 directly with the display and input hardware or via
7676 another subsystem (e.g., GGI) should provide
7677 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7678 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7684 <heading>Packages providing a terminal emulator</heading>
7687 Packages that provide a terminal emulator for the X Window
7688 System which meet the criteria listed below should declare
7689 in their control data that they provide the virtual
7690 package <tt>x-terminal-emulator</tt>. They should also
7691 register themselves as an alternative for
7692 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7697 To be an <tt>x-terminal-emulator</tt>, a program must:
7698 <list compact="compact">
7700 Be able to emulate a DEC VT100 terminal, or a
7701 compatible terminal.
7705 Support the command-line option <tt>-e
7706 <var>command</var></tt>, which creates a new
7707 terminal window<footnote>
7708 "New terminal window" does not necessarily mean
7709 a new top-level X window directly parented by
7710 the window manager; it could, if the terminal
7711 emulator application were so coded, be a new
7712 "view" in a multiple-document interface (MDI).
7714 and runs the specified <var>command</var>,
7715 interpreting the entirity of the rest of the command
7716 line as a command to pass straight to exec, in the
7717 manner that <tt>xterm</tt> does.
7721 Support the command-line option <tt>-T
7722 <var>title</var></tt>, which creates a new terminal
7723 window with the window title <var>title</var>.
7730 <heading>Packages providing a window manager</heading>
7733 Packages that provide a window manager should declare in
7734 their control data that they provide the virtual package
7735 <tt>x-window-manager</tt>. They should also register
7736 themselves as an alternative for
7737 <file>/usr/bin/x-window-manager</file>, with a priority
7738 calculated as follows:
7739 <list compact="compact">
7741 Start with a priority of 20.
7745 If the window manager supports the Debian menu
7746 system, add 20 points if this support is available
7747 in the package's default configuration (i.e., no
7748 configuration files belonging to the system or user
7749 have to be edited to activate the feature); if
7750 configuration files must be modified, add only 10
7756 If the window manager complies with <url
7757 id="http://www.freedesktop.org/Standards/wm-spec"
7758 name="The Window Manager Specification Project">,
7759 written by the <url id="http://www.freedesktop.org/"
7760 name="Free Desktop Group">, add 40 points.
7764 If the window manager permits the X session to be
7765 restarted using a <em>different</em> window manager
7766 (without killing the X server) in its default
7767 configuration, add 10 points; otherwise add none.
7774 <heading>Packages providing fonts</heading>
7777 Packages that provide fonts for the X Window
7779 For the purposes of Debian Policy, a "font for the X
7780 Window System" is one which is accessed via X protocol
7781 requests. Fonts for the Linux console, for PostScript
7782 renderers, or any other purpose, do not fit this
7783 definition. Any tool which makes such fonts available
7784 to the X Window System, however, must abide by this
7787 must do a number of things to ensure that they are both
7788 available without modification of the X or font server
7789 configuration, and that they do not corrupt files used by
7790 other font packages to register information about
7794 Fonts of any type supported by the X Window System
7795 must be in a separate binary package from any
7796 executables, libraries, or documentation (except
7797 that specific to the fonts shipped, such as their
7798 license information). If one or more of the fonts
7799 so packaged are necessary for proper operation of
7800 the package with which they are associated the font
7801 package may be Recommended; if the fonts merely
7802 provide an enhancement, a Suggests relationship may
7803 be used. Packages must not Depend on font
7805 This is because the X server may retrieve fonts
7806 from the local filesystem or over the network
7807 from an X font server; the Debian package system
7808 is empowered to deal only with the local
7814 BDF fonts must be converted to PCF fonts with the
7815 <prgn>bdftopcf</prgn> utility (available in the
7816 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7817 placed in a directory that corresponds to their
7819 <list compact="compact">
7821 100 dpi fonts must be placed in
7822 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7826 75 dpi fonts must be placed in
7827 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7831 Character-cell fonts, cursor fonts, and other
7832 low-resolution fonts must be placed in
7833 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7839 Speedo fonts must be placed in
7840 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7844 Type 1 fonts must be placed in
7845 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7846 metric files are available, they must be placed here
7851 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7852 other than those listed above must be neither
7853 created nor used. (The <file>PEX</file>, <file>CID</file>,
7854 and <file>cyrillic</file> directories are excepted for
7855 historical reasons, but installation of files into
7856 these directories remains discouraged.)
7860 Font packages may, instead of placing files directly
7861 in the X font directories listed above, provide
7862 symbolic links in that font directory pointing to
7863 the files' actual location in the filesystem. Such
7864 a location must comply with the FHS.
7868 Font packages should not contain both 75dpi and
7869 100dpi versions of a font. If both are available,
7870 they should be provided in separate binary packages
7871 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7872 the names of the packages containing the
7873 corresponding fonts.
7877 Fonts destined for the <file>misc</file> subdirectory
7878 should not be included in the same package as 75dpi
7879 or 100dpi fonts; instead, they should be provided in
7880 a separate package with <tt>-misc</tt> appended to
7885 Font packages must not provide the files
7886 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7887 <file>fonts.scale</file> in a font directory:
7890 <file>fonts.dir</file> files must not be provided at all.
7894 <file>fonts.alias</file> and <file>fonts.scale</file>
7895 files, if needed, should be provided in the
7897 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7898 where <var>fontdir</var> is the name of the
7900 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7901 package's corresponding fonts are stored
7902 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7903 <var>package</var> is the name of the package
7904 that provides these fonts, and
7905 <var>extension</var> is either <tt>scale</tt>
7906 or <tt>alias</tt>, whichever corresponds to
7913 Font packages must declare a dependency on
7914 <tt>xutils (>> 4.0.3)</tt> in their control
7919 Font packages that provide one or more
7920 <file>fonts.scale</file> files as described above must
7921 invoke <prgn>update-fonts-scale</prgn> on each
7922 directory into which they installed fonts
7923 <em>before</em> invoking
7924 <prgn>update-fonts-dir</prgn> on that directory.
7925 This invocation must occur in both the
7926 <prgn>postinst</prgn> (for all arguments) and
7927 <prgn>postrm</prgn> (for all arguments except
7928 <tt>upgrade</tt>) scripts.
7932 Font packages that provide one or more
7933 <file>fonts.alias</file> files as described above must
7934 invoke <prgn>update-fonts-alias</prgn> on each
7935 directory into which they installed fonts. This
7936 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 must invoke
7944 <prgn>update-fonts-dir</prgn> on each directory into
7945 which they installed fonts. This invocation must
7946 occur in both the <prgn>postinst</prgn> (for all
7947 arguments) and <prgn>postrm</prgn> (for all
7948 arguments except <tt>upgrade</tt>) scripts.
7952 Font packages must not provide alias names for the
7953 fonts they include which collide with alias names
7954 already in use by fonts already packaged.
7958 Font packages must not provide fonts with the same
7959 XLFD registry name as another font already packaged.
7966 <heading>Application defaults files</heading>
7969 Application defaults files must be installed in the
7970 directory <file>/etc/X11/app-defaults/</file> (use of a
7971 localized subdirectory of <file>/etc/X11/</file> as described
7972 in the <em>X Toolkit Intrinsics - C Language
7973 Interface</em> manual is also permitted). They must be
7974 registered as <tt>conffile</tt>s or handled as
7975 configuration files. Packages must not provide the
7976 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7980 Customization of programs' X resources may also be
7981 supported with the provision of a file with the same name
7982 as that of the package placed in the
7983 <file>/etc/X11/Xresources/</file> directory, which must
7984 registered as a <tt>conffile</tt> or handled as a
7985 configuration file.<footnote>
7986 Note that this mechanism is not the same as using
7987 app-defaults; app-defaults are tied to the client
7988 binary on the local filesystem, whereas X resources
7989 are stored in the X server and affect all connecting
7992 <em>Important:</em> packages that install files into the
7993 <file>/etc/X11/Xresources/</file> directory must conflict with
7994 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7995 it is possible for the installing package to destroy a
7996 previously-existing <file>/etc/X11/Xresources</file> file
7997 which had been customized by the system administrator.
8002 <heading>Installation directory issues</heading>
8005 Packages using the X Window System should not be
8006 configured to install files under the <file>/usr/X11R6/</file>
8007 directory unless they use <prgn>imake</prgn>. The
8008 <file>/usr/X11R6/</file> directory hierarchy should be
8009 regarded as deprecated for all packages except the X
8010 Window System itself, and those which use the
8011 <prgn>imake</prgn> program it provides, in which case the
8012 packages may transition out of the <file>/usr/X11R6/</file>
8013 directory at the maintainer's discretion.<footnote>
8014 <prgn>Imake</prgn>-using programs are exempt because,
8015 as long as they are written correctly, the pathnames
8016 they use to locate resources and install themselves
8017 are derived wholly from the X Window System
8018 configuration. Thus, in the event that the X Window
8019 System moves to <file>/usr/X11R7/</file>,
8020 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
8021 that is required for these programs is a recompile
8022 against the corresponding X Window System library
8023 development packages.
8028 Programs that use GNU <prgn>autoconf</prgn> and
8029 <prgn>automake</prgn> are usually easily configured at
8030 compile time to use <file>/usr/</file> instead of
8031 <file>/usr/X11R6/</file>, and this should be done whenever
8032 possible. Configuration files for window managers and
8033 display managers should be placed in a subdirectory of
8034 <file>/etc/X11/</file> corresponding to the package name due
8035 to these programs' tight integration with the mechanisms
8036 of the X Window System. Application-level programs should
8037 use the <file>/etc/</file> directory unless otherwise mandated
8042 The installation of files into subdirectories
8043 of <file>/usr/X11R6/include/X11/</file> and
8044 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8045 package maintainers should determine if subdirectories of
8046 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8047 instead. (The use of symbolic links from the
8048 <file>X11R6</file> directories to other FHS-compliant
8049 locations is encouraged if the program is not easily
8050 configured to look elsewhere for its files.)
8054 Packages must not provide or install files into the directories
8055 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8056 <file>/usr/lib/X11/</file>. Files within a package should,
8057 however, make reference to these directories, rather than
8058 their <tt>X11R6</tt>-named counterparts
8059 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8060 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8061 referred to have not been moved to other FHS-compliant
8067 <heading>The OSF/Motif and OpenMotif libraries</heading>
8070 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8071 OpenMotif libraries</em><footnote>
8072 OSF/Motif and OpenMotif are collectively referred to as
8073 "Motif" in this policy document.
8075 should be compiled against and tested with LessTif (a free
8076 re-implementation of Motif) instead. If the maintainer
8077 judges that the program or programs do not work
8078 sufficiently well with LessTif to be distributed and
8079 supported, but do so when compiled against Motif, then two
8080 versions of the package should be created; one linked
8081 statically against Motif and with <tt>-smotif</tt>
8082 appended to the package name, and one linked dynamically
8083 against Motif and with <tt>-dmotif</tt> appended to the
8088 Both Motif-linked versions are dependent
8089 upon non-DFSG-compliant software and thus cannot be
8090 uploaded to the <em>main</em> distribution; if the
8091 software is itself DFSG-compliant it may be uploaded to
8092 the <em>contrib</em> distribution. While known existing
8093 versions of Motif permit unlimited redistribution of
8094 binaries linked against the library (whether statically or
8095 dynamically), it is the package maintainer's
8096 responsibility to determine whether this is permitted by
8097 the license of the copy of Motif in their possession.
8103 <heading>Perl programs and modules</heading>
8106 Perl programs and modules should follow the current Perl policy.
8110 The Perl policy can be found in the <tt>perl-policy</tt>
8111 files in the <tt>debian-policy</tt> package.
8112 It is also available from the Debian web mirrors at
8113 <tt><url name="/doc/packaging-manuals/perl-policy/"
8114 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8119 <heading>Emacs lisp programs</heading>
8122 Please refer to the "Debian Emacs Policy" for details of how to
8123 package emacs lisp programs.
8127 The Emacs policy is available in
8128 <file>debian-emacs-policy.gz</file> of the
8129 <package>emacsen-common</package> package.
8130 It is also available from the Debian web mirrors at
8131 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8132 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8137 <heading>Games</heading>
8140 The permissions on <file>/var/games</file> are mode 755, owner
8141 <tt>root</tt> and group <tt>root</tt>.
8145 Each game decides on its own security policy.</p>
8148 Games which require protected, privileged access to
8149 high-score files, savegames, etc., may be made
8150 set-<em>group</em>-id (mode 2755) and owned by
8151 <tt>root.games</tt>, and use files and directories with
8152 appropriate permissions (770 <tt>root.games</tt>, for
8153 example). They must not be made
8154 set-<em>user</em>-id, as this causes security problems. (If
8155 an attacker can subvert any set-user-id game they can
8156 overwrite the executable of any other, causing other players
8157 of these games to run a Trojan horse program. With a
8158 set-group-id game the attacker only gets access to less
8159 important game data, and if they can get at the other
8160 players' accounts at all it will take considerably more
8164 Some packages, for example some fortune cookie programs, are
8165 configured by the upstream authors to install with their
8166 data files or other static information made unreadable so
8167 that they can only be accessed through set-id programs
8168 provided. You should not do this in a Debian package: anyone can
8169 download the <file>.deb</file> file and read the data from it,
8170 so there is no point making the files unreadable. Not
8171 making the files unreadable also means that you don't have
8172 to make so many programs set-id, which reduces the risk of a
8176 As described in the FHS, binaries of games should be
8177 installed in the directory <file>/usr/games</file>. This also
8178 applies to games that use the X Window System. Manual pages
8179 for games (X and non-X games) should be installed in
8180 <file>/usr/share/man/man6</file>.</p>
8186 <heading>Documentation</heading>
8189 <heading>Manual pages</heading>
8192 You should install manual pages in <prgn>nroff</prgn> source
8193 form, in appropriate places under <file>/usr/share/man</file>.
8194 You should only use sections 1 to 9 (see the FHS for more
8195 details). You must not install a preformatted "cat page".
8199 Each program, utility, and function should have an
8200 associated manual page included in the same package. It is
8201 suggested that all configuration files also have a manual
8202 page included as well. Manual pages for protocols and other
8203 auxiliary things are optional.
8207 If no manual page is available, this is considered as a bug
8208 and should be reported to the Debian Bug Tracking System (the
8209 maintainer of the package is allowed to write this bug report
8210 themselves, if they so desire). Do not close the bug report
8211 until a proper man page is available.<footnote>
8212 It is not very hard to write a man page. See the
8213 <url id="http://www.schweikhardt.net/man_page_howto.html"
8214 name="Man-Page-HOWTO">,
8215 <manref name="man" section="7">, the examples
8216 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8217 the helper programs <prgn>help2man</prgn>, or the
8218 directory <file>/usr/share/doc/man-db/examples</file>.
8223 You may forward a complaint about a missing man page to the
8224 upstream authors, and mark the bug as forwarded in the
8225 Debian bug tracking system. Even though the GNU Project do
8226 not in general consider the lack of a man page to be a bug,
8227 we do; if they tell you that they don't consider it a bug
8228 you should leave the bug in our bug tracking system open
8233 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8237 If one man page needs to be accessible via several names it
8238 is better to use a symbolic link than the <file>.so</file>
8239 feature, but there is no need to fiddle with the relevant
8240 parts of the upstream source to change from <file>.so</file> to
8241 symlinks: don't do it unless it's easy. You should not
8242 create hard links in the manual page directories, nor put
8243 absolute filenames in <file>.so</file> directives. The filename
8244 in a <file>.so</file> in a man page should be relative to the
8245 base of the man page tree (usually
8246 <file>/usr/share/man</file>). If you do not create any links
8247 (whether symlinks, hard links, or <tt>.so</tt> directives)
8248 in the filesystem to the alternate names of the man page,
8249 then you should not rely on <prgn>man</prgn> finding your
8250 man page under those names based solely on the information in
8251 the man page's header.<footnote>
8252 Supporting this in <prgn>man</prgn> often requires
8253 unreasonable processing time to find a manual page or to
8254 report that none exists, and moves knowledge into man's
8255 database that would be better left in the filesystem.
8256 This support is therefore deprecated and will cease to
8257 be present in the future.
8263 <heading>Info documents</heading>
8266 Info documents should be installed in <file>/usr/share/info</file>.
8267 They should be compressed with <tt>gzip -9</tt>.
8271 Your package should call <prgn>install-info</prgn> to update
8272 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8273 script when called with a <tt>configure</tt> argument, for
8275 <example compact="compact">
8276 install-info --quiet --section Development Development \
8277 /usr/share/info/foobar.info
8281 It is a good idea to specify a section for the location of
8282 your program; this is done with the <tt>--section</tt>
8283 switch. To determine which section to use, you should look
8284 at <file>/usr/share/info/dir</file> on your system and choose the most
8285 relevant (or create a new section if none of the current
8286 sections are relevant). Note that the <tt>--section</tt>
8287 flag takes two arguments; the first is a regular expression
8288 to match (case-insensitively) against an existing section,
8289 the second is used when creating a new one.</p>
8292 You should remove the entries in the <prgn>prerm</prgn>
8293 script when called with a <tt>remove</tt> argument:
8294 <example compact="compact">
8295 install-info --quiet --remove /usr/share/info/foobar.info
8299 If <prgn>install-info</prgn> cannot find a description entry
8300 in the Info file you must supply one. See <manref
8301 name="install-info" section="8"> for details.</p>
8305 <heading>Additional documentation</heading>
8308 Any additional documentation that comes with the package may
8309 be installed at the discretion of the package maintainer.
8310 Text documentation should be installed in the directory
8311 <file>/usr/share/doc/<var>package</var></file>, where
8312 <var>package</var> is the name of the package, and
8313 compressed with <tt>gzip -9</tt> unless it is small.
8317 If a package comes with large amounts of documentation which
8318 many users of the package will not require you should create
8319 a separate binary package to contain it, so that it does not
8320 take up disk space on the machines of users who do not need
8321 or want it installed.</p>
8324 It is often a good idea to put text information files
8325 (<file>README</file>s, changelogs, and so forth) that come with
8326 the source package in <file>/usr/share/doc/<var>package</var></file>
8327 in the binary package. However, you don't need to install
8328 the instructions for building and installing the package, of
8332 Packages must not require the existence of any files in
8333 <file>/usr/share/doc/</file> in order to function
8335 The system administrator should be able to
8336 delete files in <file>/usr/share/doc/</file> without causing
8337 any programs to break.
8339 Any files that are referenced by programs but are also
8340 useful as standalone documentation should be installed under
8341 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8342 <file>/usr/share/doc/<var>package</var></file>.
8346 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8347 link to another directory in <file>/usr/share/doc</file> only if
8348 the two packages both come from the same source and the
8349 first package Depends on the second.<footnote>
8351 Please note that this does not override the section on
8352 changelog files below, so the file
8353 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8354 must refer to the changelog for the current version of
8355 <var>package</var> in question. In practice, this means
8356 that the sources of the target and the destnation of the
8357 symlink must be the same (same source package and
8364 Former Debian releases placed all additional documentation
8365 in <file>/usr/doc/<var>package</var></file>. This has been
8366 changed to <file>/usr/share/doc/<var>package</var></file>,
8367 and packages must not put documentation in the directory
8368 <file>/usr/doc/<var>package</var></file>. <footnote>
8369 At this phase of the transition, we no longer require a
8370 symbolic link in <file>/usr/doc/</file>. At a later point,
8371 policy shall change to make the symbolic links a bug.
8377 <heading>Preferred documentation formats</heading>
8380 The unification of Debian documentation is being carried out
8384 If your package comes with extensive documentation in a
8385 markup format that can be converted to various other formats
8386 you should if possible ship HTML versions in a binary
8387 package, in the directory
8388 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8389 its subdirectories.<footnote>
8390 The rationale: The important thing here is that HTML
8391 docs should be available in <em>some</em> package, not
8392 necessarily in the main binary package.
8397 Other formats such as PostScript may be provided at the
8398 package maintainer's discretion.
8402 <sect id="copyrightfile">
8403 <heading>Copyright information</heading>
8406 Every package must be accompanied by a verbatim copy of its
8407 copyright and distribution license in the file
8408 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8409 file must neither be compressed nor be a symbolic link.
8413 In addition, the copyright file must say where the upstream
8414 sources (if any) were obtained. It should name the original
8415 authors of the package and the Debian maintainer(s) who were
8416 involved with its creation.</p>
8419 A copy of the file which will be installed in
8420 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8421 be in <file>debian/copyright</file> in the source package.
8425 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8426 link to another directory in <file>/usr/share/doc</file> only if
8427 the two packages both come from the same source and the
8428 first package Depends on the second. These rules are
8429 important because copyrights must be extractable by
8434 Packages distributed under the UCB BSD license, the Artistic
8435 license, the GNU GPL, and the GNU LGPL should refer to the
8436 files <file>/usr/share/common-licenses/BSD</file>,
8437 <file>/usr/share/common-licenses/Artistic</file>,
8438 <file>/usr/share/common-licenses/GPL</file>, and
8439 <file>/usr/share/common-licenses/LGPL</file> respectively,
8440 rather than quoting them in the copyright file.
8444 You should not use the copyright file as a general <file>README</file>
8445 file. If your package has such a file it should be
8446 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8447 <file>README.Debian</file> or some other appropriate place.</p>
8451 <heading>Examples</heading>
8454 Any examples (configurations, source files, whatever),
8455 should be installed in a directory
8456 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8457 files should not be referenced by any program: they're there
8458 for the benefit of the system administrator and users as
8459 documentation only. Architecture-specific example files
8460 should be installed in a directory
8461 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8463 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8464 latter directory itself may be a symbolic link to the
8469 If the purpose of a package is to provide examples, then the
8470 example files may be installed into
8471 <file>/usr/share/doc/<var>package</var></file>.
8475 <sect id="changelogs">
8476 <heading>Changelog files</heading>
8479 Packages that are not Debian-native must contain a
8480 compressed copy of the <file>debian/changelog</file> file from
8481 the Debian source tree in
8482 <file>/usr/share/doc/<var>package</var></file> with the name
8483 <file>changelog.Debian.gz</file>.
8487 If an upstream changelog is available, it should be accessible as
8488 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8489 plain text. If the upstream changelog is distributed in
8490 HTML, it should be made available in that form as
8491 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8492 and a plain text <file>changelog.gz</file> should be generated
8493 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8494 the upstream changelog files do not already conform to this
8495 naming convention, then this may be achieved either by
8496 renaming the files, or by adding a symbolic link, at the
8497 maintainer's discretion.<footnote>
8498 Rationale: People should not have to look in places for
8499 upstream changelogs merely because they are given
8500 different names or are distributed in HTML format.
8505 All of these files should be installed compressed using
8506 <tt>gzip -9</tt>, as they will become large with time even
8507 if they start out small.
8511 If the package has only one changelog which is used both as
8512 the Debian changelog and the upstream one because there is
8513 no separate upstream maintainer then that changelog should
8514 usually be installed as
8515 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8516 there is a separate upstream maintainer, but no upstream
8517 changelog, then the Debian changelog should still be called
8518 <file>changelog.Debian.gz</file>.
8522 For details about the format and contents of the Debian
8523 changelog file, please see <ref id="dpkgchangelog">.
8528 <appendix id="pkg-scope">
8529 <heading>Introduction and scope of these appendices</heading>
8532 These appendices are taken essentially verbatim from the
8533 now-deprecated Packaging Manual, version 3.2.1.0. They are
8534 the chapters which are likely to be of use to package
8535 maintainers and which have not already been included in the
8536 policy document itself. Most of these sections are very likely
8537 not relevant to policy; they should be treated as
8538 documentation for the packaging system. Please note that these
8539 appendices are included for convenience, and for historical
8540 reasons: they used to be part of policy package, and they have
8541 not yet been incorporated into dpkg documentation. However,
8542 they still have value, and hence they are presented here.
8546 They have not yet been checked to ensure that they are
8547 compatible with the contents of policy, and if there are any
8548 contradictions, the version in the main policy document takes
8549 precedence. The remaining chapters of the old Packaging
8550 Manual have also not been read in detail to ensure that there
8551 are not parts which have been left out. Both of these will be
8556 Certain parts of the Packaging manual were integrated into the
8557 Policy Manual proper, and removed from the appendices. Links
8558 have been placed from the old locations to the new ones.
8562 <prgn>dpkg</prgn> is a suite of programs for creating binary
8563 package files and installing and removing them on Unix
8565 <prgn>dpkg</prgn> is targetted primarily at Debian
8566 GNU/Linux, but may work on or be ported to other
8572 The binary packages are designed for the management of
8573 installed executable programs (usually compiled binaries) and
8574 their associated data, though source code examples and
8575 documentation are provided as part of some packages.</p>
8578 This manual describes the technical aspects of creating Debian
8579 binary packages (<file>.deb</file> files). It documents the
8580 behaviour of the package management programs
8581 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8582 they interact with packages.</p>
8585 It also documents the interaction between
8586 <prgn>dselect</prgn>'s core and the access method scripts it
8587 uses to actually install the selected packages, and describes
8588 how to create a new access method.</p>
8591 This manual does not go into detail about the options and
8592 usage of the package building and installation tools. It
8593 should therefore be read in conjuction with those programs'
8598 The utility programs which are provided with <prgn>dpkg</prgn>
8599 for managing various system configuration and similar issues,
8600 such as <prgn>update-rc.d</prgn> and
8601 <prgn>install-info</prgn>, are not described in detail here -
8602 please see their man pages.
8606 It is assumed that the reader is reasonably familiar with the
8607 <prgn>dpkg</prgn> System Administrators' manual.
8608 Unfortunately this manual does not yet exist.
8612 The Debian version of the FSF's GNU hello program is provided
8613 as an example for people wishing to create Debian
8614 packages. The Debian <prgn>debmake</prgn> package is
8615 recommended as a very helpful tool in creating and maintaining
8616 Debian packages. However, while the tools and examples are
8617 helpful, they do not replace the need to read and follow the
8618 Policy and Programmer's Manual.</p>
8621 <appendix id="pkg-binarypkg">
8622 <heading>Binary packages (from old Packaging Manual)</heading>
8625 The binary package has two main sections. The first part
8626 consists of various control information files and scripts used
8627 by <prgn>dpkg</prgn> when installing and removing. See <ref
8628 id="pkg-controlarea">.
8632 The second part is an archive containing the files and
8633 directories to be installed.
8637 In the future binary packages may also contain other
8638 components, such as checksums and digital signatures. The
8639 format for the archive is described in full in the
8640 <file>deb(5)</file> man page.
8644 <sect id="pkg-bincreating"><heading>Creating package files -
8645 <prgn>dpkg-deb</prgn>
8649 All manipulation of binary package files is done by
8650 <prgn>dpkg-deb</prgn>; it's the only program that has
8651 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8652 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8653 will spot that the options requested are appropriate to
8654 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8659 In order to create a binary package you must make a
8660 directory tree which contains all the files and directories
8661 you want to have in the filesystem data part of the package.
8662 In Debian-format source packages this directory is usually
8663 <file>debian/tmp</file>, relative to the top of the package's
8668 They should have the locations (relative to the root of the
8669 directory tree you're constructing) ownerships and
8670 permissions which you want them to have on the system when
8675 With current versions of <prgn>dpkg</prgn> the uid/username
8676 and gid/groupname mappings for the users and groups being
8677 used should be the same on the system where the package is
8678 built and the one where it is installed.
8682 You need to add one special directory to the root of the
8683 miniature filesystem tree you're creating:
8684 <prgn>DEBIAN</prgn>. It should contain the control
8685 information files, notably the binary package control file
8686 (see <ref id="pkg-controlfile">).
8690 The <prgn>DEBIAN</prgn> directory will not appear in the
8691 filesystem archive of the package, and so won't be installed
8692 by <prgn>dpkg</prgn> when the package is installed.
8696 When you've prepared the package, you should invoke:
8698 dpkg --build <var>directory</var>
8703 This will build the package in
8704 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8705 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8706 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8711 See the man page <manref name="dpkg-deb" section="8"> for details of how
8712 to examine the contents of this newly-created file. You may find the
8713 output of following commands enlightening:
8715 dpkg-deb --info <var>filename</var>.deb
8716 dpkg-deb --contents <var>filename</var>.deb
8717 dpkg --contents <var>filename</var>.deb
8719 To view the copyright file for a package you could use this command:
8721 dpkg --fsys-tarfile <var>filename</var>.deb | tar xO ./usr/share/doc/\*/copyright | pager
8726 <sect id="pkg-controlarea">
8727 <heading>Package control information files</heading>
8730 The control information portion of a binary package is a
8731 collection of files with names known to <prgn>dpkg</prgn>.
8732 It will treat the contents of these files specially - some
8733 of them contain information used by <prgn>dpkg</prgn> when
8734 installing or removing the package; others are scripts which
8735 the package maintainer wants <prgn>dpkg</prgn> to run.
8739 It is possible to put other files in the package control
8740 area, but this is not generally a good idea (though they
8741 will largely be ignored).
8745 Here is a brief list of the control info files supported by
8746 <prgn>dpkg</prgn> and a summary of what they're used for.
8751 <tag><tt>control</tt>
8754 This is the key description file used by
8755 <prgn>dpkg</prgn>. It specifies the package's name
8756 and version, gives its description for the user,
8757 states its relationships with other packages, and so
8758 forth. See <ref id="sourcecontrolfiles"> and
8759 <ref id="binarycontrolfiles">.
8763 It is usually generated automatically from information
8764 in the source package by the
8765 <prgn>dpkg-gencontrol</prgn> program, and with
8766 assistance from <prgn>dpkg-shlibdeps</prgn>.
8767 See <ref id="pkg-sourcetools">.
8771 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8776 These are exectuable files (usually scripts) which
8777 <prgn>dpkg</prgn> runs during installation, upgrade
8778 and removal of packages. They allow the package to
8779 deal with matters which are particular to that package
8780 or require more complicated processing than that
8781 provided by <prgn>dpkg</prgn>. Details of when and
8782 how they are called are in <ref id="maintainerscripts">.
8786 It is very important to make these scripts idempotent.
8787 See <ref id="idempotency">.
8791 The maintainer scripts are guaranteed to run with a
8792 controlling terminal and can interact with the user.
8793 See <ref id="controllingterminal">.
8797 <tag><tt>conffiles</tt>
8800 This file contains a list of configuration files which
8801 are to be handled automatically by <prgn>dpkg</prgn>
8802 (see <ref id="pkg-conffiles">). Note that not necessarily
8803 every configuration file should be listed here.
8806 <tag><tt>shlibs</tt>
8809 This file contains a list of the shared libraries
8810 supplied by the package, with dependency details for
8811 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8812 when it determines what dependencies are required in a
8813 package control file. The <tt>shlibs</tt> file format
8814 is described on <ref id="shlibs">.
8819 <sect id="pkg-controlfile">
8820 <heading>The main control information file: <tt>control</tt></heading>
8823 The most important control information file used by
8824 <prgn>dpkg</prgn> when it installs a package is
8825 <tt>control</tt>. It contains all the package's "vital
8830 The binary package control files of packages built from
8831 Debian sources are made by a special tool,
8832 <prgn>dpkg-gencontrol</prgn>, which reads
8833 <file>debian/control</file> and <file>debian/changelog</file> to
8834 find the information it needs. See <ref id="pkg-sourcepkg"> for
8839 The fields in binary package control files are listed in
8840 <ref id="binarycontrolfiles">.
8844 A description of the syntax of control files and the purpose
8845 of the fields is available in <ref id="controlfields">.
8850 <heading>Time Stamps</heading>
8853 See <ref id="timestamps">.
8858 <appendix id="pkg-sourcepkg">
8859 <heading>Source packages (from old Packaging Manual) </heading>
8862 The Debian binary packages in the distribution are generated
8863 from Debian sources, which are in a special format to assist
8864 the easy and automatic building of binaries.
8867 <sect id="pkg-sourcetools">
8868 <heading>Tools for processing source packages</heading>
8871 Various tools are provided for manipulating source packages;
8872 they pack and unpack sources and help build of binary
8873 packages and help manage the distribution of new versions.
8877 They are introduced and typical uses described here; see
8878 <manref name="dpkg-source" section="1"> for full
8879 documentation about their arguments and operation.
8883 For examples of how to construct a Debian source package,
8884 and how to use those utilities that are used by Debian
8885 source packages, please see the <prgn>hello</prgn> example
8889 <sect1 id="pkg-dpkg-source">
8891 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8896 This program is frequently used by hand, and is also
8897 called from package-independent automated building scripts
8898 such as <prgn>dpkg-buildpackage</prgn>.
8902 To unpack a package it is typically invoked with
8904 dpkg-source -x <var>.../path/to/filename</var>.dsc
8909 with the <file><var>filename</var>.tar.gz</file> and
8910 <file><var>filename</var>.diff.gz</file> (if applicable) in
8911 the same directory. It unpacks into
8912 <file><var>package</var>-<var>version</var></file>, and if
8914 <file><var>package</var>-<var>version</var>.orig</file>, in
8915 the current directory.
8919 To create a packed source archive it is typically invoked:
8921 dpkg-source -b <var>package</var>-<var>version</var>
8926 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8927 <file>.diff.gz</file> (if appropriate) in the current
8928 directory. <prgn>dpkg-source</prgn> does not clean the
8929 source tree first - this must be done separately if it is
8934 See also <ref id="pkg-sourcearchives">.</p>
8938 <sect1 id="pkg-dpkg-buildpackage">
8940 <prgn>dpkg-buildpackage</prgn> - overall package-building
8945 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8946 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8947 targets <tt>clean</tt>, <tt>build</tt> and
8948 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8949 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8950 source and binary package upload.
8954 It is usually invoked by hand from the top level of the
8955 built or unbuilt source directory. It may be invoked with
8956 no arguments; useful arguments include:
8957 <taglist compact="compact">
8958 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8961 Do not sign the <tt>.changes</tt> file or the
8962 source package <tt>.dsc</tt> file, respectively.</p>
8964 <tag><tt>-p<var>sign-command</var></tt></tag>
8967 Invoke <var>sign-command</var> instead of finding
8968 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8969 <var>sign-command</var> must behave just like
8970 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
8972 <tag><tt>-r<var>root-command</var></tt></tag>
8975 When root privilege is required, invoke the command
8976 <var>root-command</var>. <var>root-command</var>
8977 should invoke its first argument as a command, from
8978 the <prgn>PATH</prgn> if necessary, and pass its
8979 second and subsequent arguments to the command it
8980 calls. If no <var>root-command</var> is supplied
8981 then <var>dpkg-buildpackage</var> will take no
8982 special action to gain root privilege, so that for
8983 most packages it will have to be invoked as root to
8986 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8989 Two types of binary-only build and upload - see
8990 <manref name="dpkg-source" section="1">.
8997 <sect1 id="pkg-dpkg-gencontrol">
8999 <prgn>dpkg-gencontrol</prgn> - generates binary package
9004 This program is usually called from <file>debian/rules</file>
9005 (see <ref id="pkg-sourcetree">) in the top level of the source
9010 This is usually done just before the files and directories in the
9011 temporary directory tree where the package is being built have their
9012 permissions and ownerships set and the package is constructed using
9013 <prgn>dpkg-deb/</prgn>
9015 This is so that the control file which is produced has
9016 the right permissions
9021 <prgn>dpkg-gencontrol</prgn> must be called after all the
9022 files which are to go into the package have been placed in
9023 the temporary build directory, so that its calculation of
9024 the installed size of a package is correct.
9028 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9029 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9030 variable substitutions created by
9031 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9036 For a package which generates only one binary package, and
9037 which builds it in <file>debian/tmp</file> relative to the top
9038 of the source package, it is usually sufficient to call
9039 <prgn>dpkg-gencontrol</prgn>.
9043 Sources which build several binaries will typically need
9046 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9047 </example> The <tt>-P</tt> tells
9048 <prgn>dpkg-gencontrol</prgn> that the package is being
9049 built in a non-default directory, and the <tt>-p</tt>
9050 tells it which package's control file should be generated.
9054 <prgn>dpkg-gencontrol</prgn> also adds information to the
9055 list of files in <file>debian/files</file>, for the benefit of
9056 (for example) a future invocation of
9057 <prgn>dpkg-genchanges</prgn>.</p>
9060 <sect1 id="pkg-dpkg-shlibdeps">
9062 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9067 This program is usually called from <file>debian/rules</file>
9068 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9069 id="pkg-sourcetree">), in the top level of the source tree.
9073 Its arguments are executables.
9076 In a forthcoming dpkg version,
9077 <prgn>dpkg-shlibdeps</prgn> would be required to be
9078 called on shared libraries as well.
9081 They may be specified either in the locations in the
9082 source tree where they are created or in the locations
9083 in the temporary build tree where they are installed
9084 prior to binary package creation.
9086 </footnote> for which shared library dependencies should
9087 be included in the binary package's control file.
9091 If some of the found shared libraries should only
9092 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9093 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9094 by using the <tt>-d<var>dependency-field</var></tt> option
9095 before those executable(s). (Each <tt>-d</tt> option
9096 takes effect until the next <tt>-d</tt>.)
9100 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9101 output control file to be modified. Instead by default it
9102 adds to the <file>debian/substvars</file> file variable
9103 settings like <tt>shlibs:Depends</tt>. These variable
9104 settings must be referenced in dependency fields in the
9105 appropriate per-binary-package sections of the source
9110 For example, a package that generates an essential part
9111 which requires dependencies, and optional parts that
9112 which only require a recommendation, would separate those
9113 two sets of dependencies into two different fields.<footnote>
9114 At the time of writing, an example for this was the
9115 <package/xmms/ package, with Depends used for the xmms
9116 executable, Recommends for the plug-ins and Suggests for
9117 even more optional features provided by unzip.
9119 It can say in its <file>debian/rules</file>:
9121 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9122 -dRecommends <var>optionalpart anotheroptionalpart</var>
9124 and then in its main control file <file>debian/control</file>:
9127 Depends: ${shlibs:Pre-Depends}
9128 Recommends: ${shlibs:Recommends}
9134 Sources which produce several binary packages with
9135 different shared library dependency requirements can use
9136 the <tt>-p<var>varnameprefix</var></tt> option to override
9137 the default <tt>shlibs:</tt> prefix (one invocation of
9138 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9139 They can thus produce several sets of dependency
9140 variables, each of the form
9141 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9142 which can be referred to in the appropriate parts of the
9143 binary package control files.
9148 <sect1 id="pkg-dpkg-distaddfile">
9150 <prgn>dpkg-distaddfile</prgn> - adds a file to
9151 <file>debian/files</file>
9155 Some packages' uploads need to include files other than
9156 the source and binary package files.
9160 <prgn>dpkg-distaddfile</prgn> adds a file to the
9161 <file>debian/files</file> file so that it will be included in
9162 the <file>.changes</file> file when
9163 <prgn>dpkg-genchanges</prgn> is run.
9167 It is usually invoked from the <tt>binary</tt> target of
9168 <file>debian/rules</file>:
9170 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9172 The <var>filename</var> is relative to the directory where
9173 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9174 is usually the directory above the top level of the source
9175 tree. The <file>debian/rules</file> target should put the
9176 file there just before or just after calling
9177 <prgn>dpkg-distaddfile</prgn>.
9181 The <var>section</var> and <var>priority</var> are passed
9182 unchanged into the resulting <file>.changes</file> file.
9187 <sect1 id="pkg-dpkg-genchanges">
9189 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9194 This program is usually called by package-independent
9195 automatic building scripts such as
9196 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9201 It is usually called in the top level of a built source
9202 tree, and when invoked with no arguments will print out a
9203 straightforward <file>.changes</file> file based on the
9204 information in the source package's changelog and control
9205 file and the binary and source packages which should have
9211 <sect1 id="pkg-dpkg-parsechangelog">
9213 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9214 representation of a changelog
9218 This program is used internally by
9219 <prgn>dpkg-source</prgn> et al. It may also occasionally
9220 be useful in <file>debian/rules</file> and elsewhere. It
9221 parses a changelog, <file>debian/changelog</file> by default,
9222 and prints a control-file format representation of the
9223 information in it to standard output.
9227 <sect1 id="pkg-dpkg-architecture">
9229 <prgn>dpkg-architecture</prgn> - information about the build and
9234 This program can be used manually, but is also invoked by
9235 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9236 to set environment or make variables which specify the build and
9237 host architecture for the package building process.
9242 <sect id="pkg-sourcetree">
9243 <heading>The Debianised source tree</heading>
9246 The source archive scheme described later is intended to
9247 allow a Debianised source tree with some associated control
9248 information to be reproduced and transported easily. The
9249 Debianised source tree is a version of the original program
9250 with certain files added for the benefit of the
9251 Debianisation process, and with any other changes required
9252 made to the rest of the source code and installation
9257 The extra files created for Debian are in the subdirectory
9258 <file>debian</file> of the top level of the Debianised source
9259 tree. They are described below.
9262 <sect1 id="pkg-debianrules">
9263 <heading><file>debian/rules</file> - the main building script</heading>
9266 See <ref id="debianrules">.
9271 <sect1 id="pkg-dpkgchangelog">
9272 <heading><file>debian/changelog</file></heading>
9275 See <ref id="dpkgchangelog">.
9279 It is recommended that the entire changelog be encoded in the
9280 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9282 <url id="http://www.unicode.org/"
9283 name="Unicode">.<footnote>
9285 Support for Unicode, and specifically UTF-8, is
9286 steadily increasing among popular applications in
9287 Debian. For example, in unstable, GNOME 2 has
9288 excellent support (almost level 2) in almost all its
9289 applications; the big remaining one is gnome-terminal,
9290 of which one requires development versions in order to
9291 support UTF-8 (available in Debian experimental now if
9292 you want to play). I think that by the time sarge is
9293 released, UTF-8 support will start to hit critical
9296 I think it is fairly obvious that we need to
9297 eventually transition to UTF-8 for our package
9298 infrastructure; it is really the only sane charset in
9299 an international environment. Now, we can't switch to
9300 using UTF-8 for package control fields and the like
9301 until dpkg has better support, but one thing we can
9302 start doing today is requesting that Debian changelogs
9303 are UTF-8 encoded. At some point in time, we can start
9304 requiring them to do so.
9307 Checking for non-UTF8 characters in a changelog is
9308 trivial. Dump the file through
9309 <example>iconv -f utf-8 -t ucs-4</example>
9310 discard the output, and check the return
9311 value. If there are any characters in the stream
9312 which are invalid UTF-8 sequences, iconv will exit
9313 with an error code; and this will be the case for the
9314 vast majority of other character sets.
9319 <sect2><heading>Defining alternative changelog formats
9323 It is possible to use a different format to the standard
9324 one, by providing a parser for the format you wish to
9329 In order to have <tt>dpkg-parsechangelog</tt> run your
9330 parser, you must include a line within the last 40 lines
9331 of your file matching the Perl regular expression:
9332 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9333 parentheses should be the name of the format. For
9334 example, you might say:
9336 @@@ changelog-format: joebloggs @@@
9338 Changelog format names are non-empty strings of alphanumerics.
9342 If such a line exists then <tt>dpkg-parsechangelog</tt>
9343 will look for the parser as
9344 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9346 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9347 it is an error for it not to find it, or for it not to
9348 be an executable program. The default changelog format
9349 is <tt>dpkg</tt>, and a parser for it is provided with
9350 the <tt>dpkg</tt> package.
9354 The parser will be invoked with the changelog open on
9355 standard input at the start of the file. It should read
9356 the file (it may seek if it wishes) to determine the
9357 information required and return the parsed information
9358 to standard output in the form of a series of control
9359 fields in the standard format. By default it should
9360 return information about only the most recent version in
9361 the changelog; it should accept a
9362 <tt>-v<var>version</var></tt> option to return changes
9363 information from all versions present <em>strictly
9364 after</em> <var>version</var>, and it should then be an
9365 error for <var>version</var> not to be present in the
9371 <list compact="compact">
9372 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9373 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9374 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9375 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9376 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9377 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9378 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9383 If several versions are being returned (due to the use
9384 of <tt>-v</tt>), the urgency value should be of the
9385 highest urgency code listed at the start of any of the
9386 versions requested followed by the concatenated
9387 (space-separated) comments from all the versions
9388 requested; the maintainer, version, distribution and
9389 date should always be from the most recent version.
9393 For the format of the <tt>Changes</tt> field see
9394 <ref id="f-Changes">.
9398 If the changelog format which is being parsed always or
9399 almost always leaves a blank line between individual
9400 change notes these blank lines should be stripped out,
9401 so as to make the resulting output compact.
9405 If the changelog format does not contain date or package
9406 name information this information should be omitted from
9407 the output. The parser should not attempt to synthesise
9408 it or find it from other sources.
9412 If the changelog does not have the expected format the
9413 parser should exit with a nonzero exit status, rather
9414 than trying to muddle through and possibly generating
9419 A changelog parser may not interact with the user at
9425 <sect1 id="pkg-srcsubstvars">
9426 <heading><file>debian/substvars</file> and variable substitutions</heading>
9429 See <ref id="substvars">.
9435 <heading><file>debian/files</file></heading>
9438 See <ref id="debianfiles">.
9442 <sect1><heading><file>debian/tmp</file>
9446 This is the canonical temporary location for the
9447 construction of binary packages by the <tt>binary</tt>
9448 target. The directory <file>tmp</file> serves as the root of
9449 the filesystem tree as it is being constructed (for
9450 example, by using the package's upstream makefiles install
9451 targets and redirecting the output there), and it also
9452 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9453 id="pkg-bincreating">.
9457 If several binary packages are generated from the same
9458 source tree it is usual to use several
9459 <file>debian/tmp<var>something</var></file> directories, for
9460 example <file>tmp-a</file> or <file>tmp-doc</file>.
9464 Whatever <file>tmp</file> directories are created and used by
9465 <tt>binary</tt> must of course be removed by the
9466 <tt>clean</tt> target.</p></sect1>
9470 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9474 As it exists on the FTP site, a Debian source package
9475 consists of three related files. You must have the right
9476 versions of all three to be able to use them.
9481 <tag>Debian source control file - <tt>.dsc</tt></tag>
9483 This file is a control file used by <prgn>dpkg-source</prgn>
9484 to extract a source package.
9485 See <ref id="debiansourcecontrolfiles">.
9489 Original source archive -
9491 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9497 This is a compressed (with <tt>gzip -9</tt>)
9498 <prgn>tar</prgn> file containing the source code from
9499 the upstream authors of the program.
9504 Debianisation diff -
9506 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9512 This is a unified context diff (<tt>diff -u</tt>)
9513 giving the changes which are required to turn the
9514 original source into the Debian source. These changes
9515 may only include editing and creating plain files.
9516 The permissions of files, the targets of symbolic
9517 links and the characteristics of special files or
9518 pipes may not be changed and no files may be removed
9523 All the directories in the diff must exist, except the
9524 <file>debian</file> subdirectory of the top of the source
9525 tree, which will be created by
9526 <prgn>dpkg-source</prgn> if necessary when unpacking.
9530 The <prgn>dpkg-source</prgn> program will
9531 automatically make the <file>debian/rules</file> file
9532 executable (see below).</p></item>
9537 If there is no original source code - for example, if the
9538 package is specially prepared for Debian or the Debian
9539 maintainer is the same as the upstream maintainer - the
9540 format is slightly different: then there is no diff, and the
9542 <file><var>package</var>_<var>version</var>.tar.gz</file>,
9543 and preferably contains a directory named
9544 <file><var>package</var>-<var>version</var></file>.
9549 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9552 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9553 Debian source package. However, if it is not available it
9554 is possible to unpack a Debian source archive as follows:
9555 <enumlist compact="compact">
9558 Untar the tarfile, which will create a <file>.orig</file>
9562 <p>Rename the <file>.orig</file> directory to
9563 <file><var>package</var>-<var>version</var></file>.</p>
9567 Create the subdirectory <file>debian</file> at the top of
9568 the source tree.</p>
9570 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9572 <item><p>Untar the tarfile again if you want a copy of the original
9573 source code alongside the Debianised version.</p>
9578 It is not possible to generate a valid Debian source archive
9579 without using <prgn>dpkg-source</prgn>. In particular,
9580 attempting to use <prgn>diff</prgn> directly to generate the
9581 <file>.diff.gz</file> file will not work.
9585 <heading>Restrictions on objects in source packages</heading>
9588 The source package may not contain any hard links
9590 This is not currently detected when building source
9591 packages, but only when extracting
9595 Hard links may be permitted at some point in the
9596 future, but would require a fair amount of
9598 </footnote>, device special files, sockets or setuid or
9601 Setgid directories are allowed.
9606 The source packaging tools manage the changes between the
9607 original and Debianised source using <prgn>diff</prgn> and
9608 <prgn>patch</prgn>. Turning the original source tree as
9609 included in the <file>.orig.tar.gz</file> into the debianised
9610 source must not involve any changes which cannot be
9611 handled by these tools. Problematic changes which cause
9612 <prgn>dpkg-source</prgn> to halt with an error when
9613 building the source package are:
9614 <list compact="compact">
9615 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9617 <item><p>Changing the targets of symbolic links.</p>
9619 <item><p>Creating directories, other than <file>debian</file>.</p>
9621 <item><p>Changes to the contents of binary files.</p></item>
9622 </list> Changes which cause <prgn>dpkg-source</prgn> to
9623 print a warning but continue anyway are:
9624 <list compact="compact">
9627 Removing files, directories or symlinks.
9629 Renaming a file is not treated specially - it is
9630 seen as the removal of the old file (which
9631 generates a warning, but is otherwise ignored),
9632 and the creation of the new one.
9638 Changed text files which are missing the usual final
9639 newline (either in the original or the modified
9644 Changes which are not represented, but which are not detected by
9645 <prgn>dpkg-source</prgn>, are:
9646 <list compact="compact">
9647 <item><p>Changing the permissions of files (other than
9648 <file>debian/rules</file>) and directories.</p></item>
9653 The <file>debian</file> directory and <file>debian/rules</file>
9654 are handled specially by <prgn>dpkg-source</prgn> - before
9655 applying the changes it will create the <file>debian</file>
9656 directory, and afterwards it will make
9657 <file>debian/rules</file> world-exectuable.
9663 <appendix id="pkg-controlfields">
9664 <heading>Control files and their fields (from old Packaging Manual)</heading>
9667 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9668 data in a common format, known as control files. Binary and
9669 source packages have control data as do the <file>.changes</file>
9670 files which control the installation of uploaded files, and
9671 <prgn>dpkg</prgn>'s internal databases are in a similar
9676 <heading>Syntax of control files</heading>
9679 See <ref id="controlsyntax">.
9683 It is important to note that there are several fields which
9684 are optional as far as <prgn>dpkg</prgn> and the related
9685 tools are concerned, but which must appear in every Debian
9686 package, or whose omission may cause problems.
9691 <heading>List of fields</heading>
9694 See <ref id="controlfieldslist">.
9698 This section now contains only the fields that didn't belong
9699 to the Policy manual.
9702 <sect1 id="pkg-f-Filename">
9703 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9706 These fields in <tt>Packages</tt> files give the
9707 filename(s) of (the parts of) a package in the
9708 distribution directories, relative to the root of the
9709 Debian hierarchy. If the package has been split into
9710 several parts the parts are all listed in order, separated
9715 <sect1 id="pkg-f-Size">
9716 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9719 These fields in <file>Packages</file> files give the size (in
9720 bytes, expressed in decimal) and MD5 checksum of the
9721 file(s) which make(s) up a binary package in the
9722 distribution. If the package is split into several parts
9723 the values for the parts are listed in order, separated by
9728 <sect1 id="pkg-f-Status">
9729 <heading><tt>Status</tt></heading>
9732 This field in <prgn>dpkg</prgn>'s status file records
9733 whether the user wants a package installed, removed or
9734 left alone, whether it is broken (requiring
9735 reinstallation) or not and what its current state on the
9736 system is. Each of these pieces of information is a
9741 <sect1 id="pkg-f-Config-Version">
9742 <heading><tt>Config-Version</tt></heading>
9745 If a package is not installed or not configured, this
9746 field in <prgn>dpkg</prgn>'s status file records the last
9747 version of the package which was successfully
9752 <sect1 id="pkg-f-Conffiles">
9753 <heading><tt>Conffiles</tt></heading>
9756 This field in <prgn>dpkg</prgn>'s status file contains
9757 information about the automatically-managed configuration
9758 files held by a package. This field should <em>not</em>
9759 appear anywhere in a package!
9764 <heading>Obsolete fields</heading>
9767 These are still recognised by <prgn>dpkg</prgn> but should
9768 not appear anywhere any more.
9770 <taglist compact="compact">
9772 <tag><tt>Revision</tt></tag>
9773 <tag><tt>Package-Revision</tt></tag>
9774 <tag><tt>Package_Revision</tt></tag>
9776 The Debian revision part of the package version was
9777 at one point in a separate control file field. This
9778 field went through several names.
9781 <tag><tt>Recommended</tt></tag>
9782 <item>Old name for <tt>Recommends</tt>.</item>
9784 <tag><tt>Optional</tt></tag>
9785 <item>Old name for <tt>Suggests</tt>.</item>
9787 <tag><tt>Class</tt></tag>
9788 <item>Old name for <tt>Priority</tt>.</item>
9797 <appendix id="pkg-conffiles">
9798 <heading>Configuration file handling (from old Packaging Manual)</heading>
9801 <prgn>dpkg</prgn> can do a certain amount of automatic
9802 handling of package configuration files.
9806 Whether this mechanism is appropriate depends on a number of
9807 factors, but basically there are two approaches to any
9808 particular configuration file.
9812 The easy method is to ship a best-effort configuration in the
9813 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9814 handle updates. If the user is unlikely to want to edit the
9815 file, but you need them to be able to without losing their
9816 changes, and a new package with a changed version of the file
9817 is only released infrequently, this is a good approach.
9821 The hard method is to build the configuration file from
9822 scratch in the <prgn>postinst</prgn> script, and to take the
9823 responsibility for fixing any mistakes made in earlier
9824 versions of the package automatically. This will be
9825 appropriate if the file is likely to need to be different on
9829 <sect><heading>Automatic handling of configuration files by
9834 A package may contain a control area file called
9835 <tt>conffiles</tt>. This file should be a list of filenames
9836 of configuration files needing automatic handling, separated
9837 by newlines. The filenames should be absolute pathnames,
9838 and the files referred to should actually exist in the
9843 When a package is upgraded <prgn>dpkg</prgn> will process
9844 the configuration files during the configuration stage,
9845 shortly before it runs the package's <prgn>postinst</prgn>
9850 For each file it checks to see whether the version of the
9851 file included in the package is the same as the one that was
9852 included in the last version of the package (the one that is
9853 being upgraded from); it also compares the version currently
9854 installed on the system with the one shipped with the last
9859 If neither the user nor the package maintainer has changed
9860 the file, it is left alone. If one or the other has changed
9861 their version, then the changed version is preferred - i.e.,
9862 if the user edits their file, but the package maintainer
9863 doesn't ship a different version, the user's changes will
9864 stay, silently, but if the maintainer ships a new version
9865 and the user hasn't edited it the new version will be
9866 installed (with an informative message). If both have
9867 changed their version the user is prompted about the problem
9868 and must resolve the differences themselves.
9872 The comparisons are done by calculating the MD5 message
9873 digests of the files, and storing the MD5 of the file as it
9874 was included in the most recent version of the package.
9878 When a package is installed for the first time
9879 <prgn>dpkg</prgn> will install the file that comes with it,
9880 unless that would mean overwriting a file already on the
9885 However, note that <prgn>dpkg</prgn> will <em>not</em>
9886 replace a conffile that was removed by the user (or by a
9887 script). This is necessary because with some programs a
9888 missing file produces an effect hard or impossible to
9889 achieve in another way, so that a missing file needs to be
9890 kept that way if the user did it.
9894 Note that a package should <em>not</em> modify a
9895 <prgn>dpkg</prgn>-handled conffile in its maintainer
9896 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9897 the user confusing and possibly dangerous options for
9898 conffile update when the package is upgraded.</p>
9901 <sect><heading>Fully-featured maintainer script configuration
9906 For files which contain site-specific information such as
9907 the hostname and networking details and so forth, it is
9908 better to create the file in the package's
9909 <prgn>postinst</prgn> script.
9913 This will typically involve examining the state of the rest
9914 of the system to determine values and other information, and
9915 may involve prompting the user for some information which
9916 can't be obtained some other way.
9920 When using this method there are a couple of important
9921 issues which should be considered:
9925 If you discover a bug in the program which generates the
9926 configuration file, or if the format of the file changes
9927 from one version to the next, you will have to arrange for
9928 the postinst script to do something sensible - usually this
9929 will mean editing the installed configuration file to remove
9930 the problem or change the syntax. You will have to do this
9931 very carefully, since the user may have changed the file,
9932 perhaps to fix the very problem that your script is trying
9933 to deal with - you will have to detect these situations and
9934 deal with them correctly.
9938 If you do go down this route it's probably a good idea to
9939 make the program that generates the configuration file(s) a
9940 separate program in <file>/usr/sbin</file>, by convention called
9941 <file><var>package</var>config</file> and then run that if
9942 appropriate from the post-installation script. The
9943 <tt><var>package</var>config</tt> program should not
9944 unquestioningly overwrite an existing configuration - if its
9945 mode of operation is geared towards setting up a package for
9946 the first time (rather than any arbitrary reconfiguration
9947 later) you should have it check whether the configuration
9948 already exists, and require a <tt>--force</tt> flag to
9949 overwrite it.</p></sect>
9952 <appendix id="pkg-alternatives"><heading>Alternative versions of
9953 an interface - <prgn>update-alternatives</prgn> (from old
9958 When several packages all provide different versions of the
9959 same program or file it is useful to have the system select a
9960 default, but to allow the system administrator to change it
9961 and have their decisions respected.
9965 For example, there are several versions of the <prgn>vi</prgn>
9966 editor, and there is no reason to prevent all of them from
9967 being installed at once, each under their own name
9968 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9969 Nevertheless it is desirable to have the name <tt>vi</tt>
9970 refer to something, at least by default.
9974 If all the packages involved cooperate, this can be done with
9975 <prgn>update-alternatives</prgn>.
9979 Each package provides its own version under its own name, and
9980 calls <prgn>update-alternatives</prgn> in its postinst to
9981 register its version (and again in its prerm to deregister
9986 See the man page <manref name="update-alternatives"
9987 section="8"> for details.
9991 If <prgn>update-alternatives</prgn> does not seem appropriate
9992 you may wish to consider using diversions instead.</p>
9995 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9996 package's version of a file (from old Packaging Manual)
10000 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10001 when it reinstalls the package it belongs to, and to have it
10002 put the file from the package somewhere else instead.
10006 This can be used locally to override a package's version of a
10007 file, or by one package to override another's version (or
10008 provide a wrapper for it).
10012 Before deciding to use a diversion, read <ref
10013 id="pkg-alternatives"> to see if you really want a diversion
10014 rather than several alternative versions of a program.
10018 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10019 and updated by a special program <prgn>dpkg-divert</prgn>.
10020 Please see <manref name="dpkg-divert" section="8"> for full
10021 details of its operation.
10025 When a package wishes to divert a file from another, it should
10026 call <prgn>dpkg-divert</prgn> in its preinst to add the
10027 diversion and rename the existing file. For example,
10028 supposing that a <prgn>smailwrapper</prgn> package wishes to
10029 install a wrapper around <file>/usr/sbin/smail</file>:
10031 if [ install = "$1" ]; then
10032 dpkg-divert --package smailwrapper --add --rename \
10033 --divert /usr/sbin/smail.real /usr/sbin/smail
10035 </example> Testing <tt>$1</tt> is necessary so that the script
10036 doesn't try to add the diversion again when
10037 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10038 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10039 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10040 get installed as the true version.
10044 The postrm has to do the reverse:
10046 if [ remove = "$1" ]; then
10047 dpkg-divert --package smailwrapper --remove --rename \
10048 --divert /usr/sbin/smail.real /usr/sbin/smail
10054 Do not attempt to divert a file which is vitally important for
10055 the system's operation - when using <prgn>dpkg-divert</prgn>
10056 there is a time, after it has been diverted but before
10057 <prgn>dpkg</prgn> has installed the new version, when the file
10058 does not exist.</p>
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