1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy" id="http://packages.debian.org/debian-policy"></package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>.
168 Also available from the same directory are several other
169 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
170 and <file>policy.ps.gz</file>.
174 The <package>debian-policy</package> package also includes the file
175 <file>upgrading-checklist.txt</file> which indicates policy
176 changes between versions of this document.
181 <heading>Authors and Maintainers</heading>
184 Originally called "Debian GNU/Linux Policy Manual", this
185 manual was initially written in 1996 by Ian Jackson.
186 It was revised on November 27th, 1996 by David A. Morris.
187 Christian Schwarz added new sections on March 15th, 1997,
188 and reworked/restructured it in April-July 1997.
189 Christoph Lameter contributed the "Web Standard".
190 Julian Gilbey largely restructured it in 2001.
194 Since September 1998, the responsibility for the contents of
195 this document lies on the <url name="debian-policy mailing list"
196 id="mailto:debian-policy@lists.debian.org">. Proposals
197 are discussed there and inserted into policy after a certain
198 consensus is established.
199 <!-- insert shameless policy-process plug here eventually -->
200 The actual editing is done by a group of maintainers that have
201 no editorial powers. These are the current maintainers:
204 <item>Julian Gilbey</item>
205 <item>Branden Robinson</item>
206 <item>Josip Rodin</item>
207 <item>Manoj Srivastava</item>
212 While the authors of this document have tried hard to avoid
213 typos and other errors, these do still occur. If you discover
214 an error in this manual or if you want to give any
215 comments, suggestions, or criticisms please send an email to
216 the Debian Policy List,
217 <email>debian-policy@lists.debian.org</email>, or submit a
218 bug report against the <tt>debian-policy</tt> package.
222 Please do not try to reach the individual authors or maintainers
223 of the Policy Manual regarding changes to the Policy.
228 <heading>Related documents</heading>
231 There are several other documents other than this Policy Manual
232 that are necessary to fully understand some Debian policies and
237 The external "sub-policy" documents are referred to in:
238 <list compact="compact">
239 <item><ref id="fhs"></item>
240 <item><ref id="virtual_pkg"></item>
241 <item><ref id="menus"></item>
242 <item><ref id="mime"></item>
243 <item><ref id="perl"></item>
244 <item><ref id="maintscriptprompt"></item>
245 <item><ref id="emacs"></item>
250 In addition to those, which carry the weight of policy, there
251 is the Debian Developer's Reference. This document describes
252 procedures and resources for Debian developers, but it is
253 <em>not</em> normative; rather, it includes things that don't
254 belong in the Policy, such as best practices for developers.
258 The Developer's Reference is available in the
259 <package>developers-reference</package> package.
260 It's also available from the Debian web mirrors at
261 <tt><url name="/doc/developers-reference/"
262 id="http://www.debian.org/doc/developers-reference/"></tt>.
270 <heading>The Debian Archive</heading>
273 The Debian GNU/Linux system is maintained and distributed as a
274 collection of <em>packages</em>. Since there are so many of
275 them (currently well over 6000), they are split into
276 <em>sections</em> and given <em>priorities</em> to simplify
277 the handling of them.
281 The effort of the Debian project is to build a free operating
282 system, but not every package we want to make accessible is
283 <em>free</em> in our sense (see the Debian Free Software
284 Guidelines, below), or may be imported/exported without
285 restrictions. Thus, the archive is split into the sections
286 based on their licenses and other restrictions.
290 The aims of this are:
292 <list compact="compact">
293 <item>to allow us to make as much software available as we can</item>
294 <item>to allow us to encourage everyone to write free software,
296 <item>to allow us to make it easy for people to produce
297 CD-ROMs of our system without violating any licenses,
298 import/export restrictions, or any other laws.</item>
303 The <em>main</em> and the <em>non-US/main</em> sections
304 together form the <em>Debian GNU/Linux distribution</em>.
308 Packages in the other sections are not considered to be part
309 of the Debian distribution, although we support their use and
310 provide infrastructure for them (such as our bug-tracking
311 system and mailing lists). This Debian Policy Manual applies
312 to these packages as well.
316 <heading>The Debian Free Software Guidelines</heading>
318 The Debian Free Software Guidelines (DFSG) form our
319 definition of "free software". These are:
321 <tag>Free Redistribution
324 The license of a Debian component may not restrict any
325 party from selling or giving away the software as a
326 component of an aggregate software distribution
327 containing programs from several different
328 sources. The license may not require a royalty or
329 other fee for such sale.
334 The program must include source code, and must allow
335 distribution in source code as well as compiled form.
340 The license must allow modifications and derived
341 works, and must allow them to be distributed under the
342 same terms as the license of the original software.
344 <tag>Integrity of The Author's Source Code
347 The license may restrict source-code from being
348 distributed in modified form <em>only</em> if the
349 license allows the distribution of "patch files"
350 with the source code for the purpose of modifying the
351 program at build time. The license must explicitly
352 permit distribution of software built from modified
353 source code. The license may require derived works to
354 carry a different name or version number from the
355 original software. (This is a compromise. The Debian
356 Project encourages all authors to not restrict any
357 files, source or binary, from being modified.)
359 <tag>No Discrimination Against Persons or Groups
362 The license must not discriminate against any person
365 <tag>No Discrimination Against Fields of Endeavor
368 The license must not restrict anyone from making use
369 of the program in a specific field of endeavor. For
370 example, it may not restrict the program from being
371 used in a business, or from being used for genetic
374 <tag>Distribution of License
377 The rights attached to the program must apply to all
378 to whom the program is redistributed without the need
379 for execution of an additional license by those
382 <tag>License Must Not Be Specific to Debian
385 The rights attached to the program must not depend on
386 the program's being part of a Debian system. If the
387 program is extracted from Debian and used or
388 distributed without Debian but otherwise within the
389 terms of the program's license, all parties to whom
390 the program is redistributed must have the same
391 rights as those that are granted in conjunction with
394 <tag>License Must Not Contaminate Other Software
397 The license must not place restrictions on other
398 software that is distributed along with the licensed
399 software. For example, the license must not insist
400 that all other programs distributed on the same medium
401 must be free software.
403 <tag>Example Licenses
406 The "GPL," "BSD," and "Artistic" licenses are examples of
407 licenses that we consider <em>free</em>.
414 <heading>Sections</heading>
417 <heading>The main section</heading>
420 Every package in <em>main</em> and <em>non-US/main</em>
421 must comply with the DFSG (Debian Free Software
426 In addition, the packages in <em>main</em>
427 <list compact="compact">
429 must not require a package outside of <em>main</em>
430 for compilation or execution (thus, the package must
431 not declare a "Depends", "Recommends", or
432 "Build-Depends" relationship on a non-<em>main</em>
436 must not be so buggy that we refuse to support them,
440 must meet all policy requirements presented in this
447 Similarly, the packages in <em>non-US/main</em>
448 <list compact="compact">
450 must not require a package outside of <em>main</em>
451 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
458 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
479 must not be so buggy that we refuse to support them,
483 must meet all policy requirements presented in this
490 Furthermore, packages in <em>contrib</em> must not require
491 a package in a <em>non-US</em> section for compilation or
496 Examples of packages which would be included in
497 <em>contrib</em> or <em>non-US/contrib</em> are:
498 <list compact="compact">
500 free packages which require <em>contrib</em>,
501 <em>non-free</em> packages or packages which are not
502 in our archive at all for compilation or execution,
506 wrapper packages or other sorts of free accessories for
513 <sect1 id="non-free">
514 <heading>The non-free section</heading>
517 Packages must be placed in <em>non-free</em> or
518 <em>non-US/non-free</em> if they are not compliant with
519 the DFSG or are encumbered by patents or other legal
520 issues that make their distribution problematic.
524 In addition, the packages in <em>non-free</em> and
525 <em>non-US/non-free</em>
526 <list compact="compact">
528 must not be so buggy that we refuse to support them,
532 must meet all policy requirements presented in this
533 manual that it is possible for them to meet.
535 It is possible that there are policy
536 requirements which the package is unable to
537 meet, for example, if the source is
538 unavailable. These situations will need to be
539 handled on a case-by-case basis.
547 <heading>The non-US sections</heading>
550 Non-free programs with cryptographic program code need to
551 be stored on the <em>non-us</em> server because of export
552 restrictions of the U.S.
556 Programs which use patented algorithms that have a
557 restricted license also need to be stored on "non-us",
558 since the non-us archive is located in a country where
559 patenting algorithms is not allowed.
563 A package depends on another package which is distributed
564 via the non-us server has to be stored on the non-us
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of
575 its copyright and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Subsections</heading>
653 The packages in the sections <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further
655 into <em>subsections</em> to simplify handling.
659 The section and subsection for each package should be
660 specified in the package's <tt>Section</tt> control
661 record (see <ref id="f-Section">).
662 However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
668 <em>subsection</em> if the package is in the
669 <em>main</em> section,
672 <em>section/subsection</em> if the package is in
673 the <em>contrib</em> or <em>non-free</em> section,
677 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
678 <tt>non-US/non-free</tt> if the package is in
679 <em>non-US/main</em>, <em>non-US/contrib</em> or
680 <em>non-US/non-free</em> respectively.
686 The Debian archive maintainers provide the authoritative
687 list of subsections. At present, they are:
688 <em>admin</em>, <em>base</em>, <em>comm</em>,
689 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
690 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
691 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
692 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
693 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
694 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
695 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
696 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
697 <em>science</em>, <em>shells</em>,
698 <em>sound</em>, <em>tex</em>, <em>text</em>,
699 <em>utils</em>, <em>web</em>, <em>x11</em>.
703 <sect id="priorities">
704 <heading>Priorities</heading>
707 Each package should have a <em>priority</em> value, which is
708 included in the package's <em>control record</em>
709 (see <ref id="f-Priority">).
710 This information is used by the Debian package management tools to
711 separate high-priority packages from less-important packages.
715 The following <em>priority levels</em> are recognised by the
716 Debian package management tools.
718 <tag><tt>required</tt></tag>
720 Packages which are necessary for the proper
721 functioning of the system. You must not remove these
722 packages or your system may become totally broken and
723 you may not even be able to use <prgn>dpkg</prgn> to
724 put things back. Systems with only the
725 <tt>required</tt> packages are probably unusable, but
726 they do have enough functionality to allow the
727 sysadmin to boot and install more software.
729 <tag><tt>important</tt></tag>
731 Important programs, including those which one would
732 expect to find on any Unix-like system. If the
733 expectation is that an experienced Unix person who
734 found it missing would say "What on earth is going on,
735 where is <prgn>foo</prgn>?", it must be an
736 <tt>important</tt> package.<footnote>
737 This is an important criterion because we are
738 trying to produce, amongst other things, a free
741 Other packages without which the system will not run
742 well or be usable must also have priority
743 <tt>important</tt>. This does
744 <em>not</em> include Emacs, the X Window System, TeX
745 or any other large applications. The
746 <tt>important</tt> packages are just a bare minimum of
747 commonly-expected and necessary tools.
749 <tag><tt>standard</tt></tag>
751 These packages provide a reasonably small but not too
752 limited character-mode system. This is what will be
753 installed by default if the user doesn't select anything
754 else. It doesn't include many large applications.
756 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
767 <tag><tt>extra</tt></tag>
769 This contains all packages that conflict with others
770 with required, important, standard or optional
771 priorities, or are only likely to be useful if you
772 already know what they are or have specialised
779 Packages must not depend on packages with lower priority
780 values (excluding build-time dependencies). In order to
781 ensure this, the priorities of one or more packages may need
790 <heading>Binary packages</heading>
793 The Debian GNU/Linux distribution is based on the Debian
794 package management system, called <prgn>dpkg</prgn>. Thus,
795 all packages in the Debian distribution must be provided
796 in the <tt>.deb</tt> file format.
800 <heading>The package name</heading>
803 Every package must have a name that's unique within the Debian
808 The package name is included in the control field
809 <tt>Package</tt>, the format of which is described
810 in <ref id="f-Package">.
811 The package name is also included as a part of the file name
812 of the <tt>.deb</tt> file.
817 <heading>The version of a package</heading>
820 Every package has a version number recorded in its
821 <tt>Version</tt> control file field, described in
822 <ref id="f-Version">.
826 The package management system imposes an ordering on version
827 numbers, so that it can tell whether packages are being up- or
828 downgraded and so that package system front end applications
829 can tell whether a package it finds available is newer than
830 the one installed on the system. The version number format
831 has the most significant parts (as far as comparison is
832 concerned) at the beginning.
836 If an upstream package has problematic version numbers they
837 should be converted to a sane form for use in the
838 <tt>Version</tt> field.
842 <heading>Version numbers based on dates</heading>
845 In general, Debian packages should use the same version
846 numbers as the upstream sources.
850 However, in some cases where the upstream version number is
851 based on a date (e.g., a development "snapshot" release) the
852 package management system cannot handle these version
853 numbers without epochs. For example, dpkg will consider
854 "96May01" to be greater than "96Dec24".
858 To prevent having to use epochs for every new upstream
859 version, the date based portion of the version number
860 should be changed to the following format in such cases:
861 "19960501", "19961224". It is up to the maintainer whether
862 they want to bother the upstream maintainer to change
863 the version numbers upstream, too.
867 Note that other version formats based on dates which are
868 parsed correctly by the package management system should
869 <em>not</em> be changed.
873 Native Debian packages (i.e., packages which have been
874 written especially for Debian) whose version numbers include
875 dates should always use the "YYYYMMDD" format.
882 <heading>The maintainer of a package</heading>
885 Every package must have a Debian maintainer (the
886 maintainer may be one person or a group of people
887 reachable from a common email address, such as a mailing
888 list). The maintainer is responsible for ensuring that
889 the package is placed in the appropriate distributions.
893 The maintainer must be specified in the
894 <tt>Maintainer</tt> control field with their correct name
895 and a working email address. If one person maintains
896 several packages, they should try to avoid having
897 different forms of their name and email address in
898 the <tt>Maintainer</tt> fields of those packages.
902 The format of the <tt>Maintainer</tt> control field is
903 described in <ref id="f-Maintainer">.
907 If the maintainer of a package quits from the Debian
908 project, "Debian QA Group"
909 <email>packages@qa.debian.org</email> takes over the
910 maintainership of the package until someone else
911 volunteers for that task. These packages are called
912 <em>orphaned packages</em>.<footnote>
913 The detailed procedure for doing this gracefully can
914 be found in the Debian Developer's Reference,
915 see <ref id="related">.
920 <sect id="descriptions">
921 <heading>The description of a package</heading>
924 Every Debian package must have an extended description
925 stored in the appropriate field of the control record.
926 The technical information about the format of the
927 <tt>Description</tt> field is in <ref id="f-Description">.
931 The description should describe the package (the program) to a
932 user (system administrator) who has never met it before so that
933 they have enough information to decide whether they want to
934 install it. This description should not just be copied verbatim
935 from the program's documentation.
939 Put important information first, both in the synopsis and
940 extended description. Sometimes only the first part of the
941 synopsis or of the description will be displayed. You can
942 assume that there will usually be a way to see the whole
943 extended description.
947 The description should also give information about the
948 significant dependencies and conflicts between this package
949 and others, so that the user knows why these dependencies and
950 conflicts have been declared.
954 Instructions for configuring or using the package should
955 not be included (that is what installation scripts,
956 manual pages, info files, etc., are for). Copyright
957 statements and other administrivia should not be included
958 either (that is what the copyright file is for).
961 <sect1 id="synopsis"><heading>The single line synopsis</heading>
964 The single line synopsis should be kept brief - certainly
969 Do not include the package name in the synopsis line. The
970 display software knows how to display this already, and you
971 do not need to state it. Remember that in many situations
972 the user may only see the synopsis line - make it as
973 informative as you can.
978 <sect1 id="extendeddesc"><heading>The extended description</heading>
981 Do not try to continue the single line synopsis into the
982 extended description. This will not work correctly when
983 the full description is displayed, and makes no sense
984 where only the summary (the single line synopsis) is
989 The extended description should describe what the package
990 does and how it relates to the rest of the system (in terms
991 of, for example, which subsystem it is which part of).
995 The description field needs to make sense to anyone, even
996 people who have no idea about any of the things the
997 package deals with.<footnote>
998 The blurb that comes with a program in its
999 announcements and/or <prgn>README</prgn> files is
1000 rarely suitable for use in a description. It is
1001 usually aimed at people who are already in the
1002 community where the package is used.
1011 <heading>Dependencies</heading>
1014 Every package must specify the dependency information
1015 about other packages that are required for the first to
1020 For example, a dependency entry must be provided for any
1021 shared libraries required by a dynamically-linked executable
1022 binary in a package.
1026 Packages are not required to declare any dependencies they
1027 have on other packages which are marked <tt>Essential</tt>
1028 (see below), and should not do so unless they depend on a
1029 particular version of that package.
1033 Sometimes, a package requires another package to be installed
1034 <em>and</em> configured before it can be installed. In this
1035 case, you must specify a <tt>Pre-Depends</tt> entry for
1040 You should not specify a <tt>Pre-Depends</tt> entry for a
1041 package before this has been discussed on the
1042 <tt>debian-devel</tt> mailing list and a consensus about
1043 doing that has been reached.
1047 The format of the package interrelationship control fields is
1048 described in <ref id="relationships">.
1052 <sect id="virtual_pkg">
1053 <heading>Virtual packages</heading>
1056 Sometimes, there are several packages which offer
1057 more-or-less the same functionality. In this case, it's
1058 useful to define a <em>virtual package</em> whose name
1059 describes that common functionality. (The virtual
1060 packages only exist logically, not physically; that's why
1061 they are called <em>virtual</em>.) The packages with this
1062 particular function will then <em>provide</em> the virtual
1063 package. Thus, any other package requiring that function
1064 can simply depend on the virtual package without having to
1065 specify all possible packages individually.
1069 All packages should use virtual package names where
1070 appropriate, and arrange to create new ones if necessary.
1071 They should not use virtual package names (except privately,
1072 amongst a cooperating group of packages) unless they have
1073 been agreed upon and appear in the list of virtual package
1074 names. (See also <ref id="virtual">)
1078 The latest version of the authoritative list of virtual
1079 package names can be found in the <tt>debian-policy</tt> package.
1080 It is also available from the Debian web mirrors at
1081 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1082 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1086 The procedure for updating the list is described in the preface
1093 <heading>Base system</heading>
1096 The <tt>base system</tt> is a minimum subset of the Debian
1097 GNU/Linux system that is installed before everything else
1098 on a new system. Thus, only very few packages are allowed
1099 to go into the <tt>base</tt> section to keep the required
1100 disk usage very small.
1104 Most of these packages will have the priority value
1105 <tt>required</tt> or at least <tt>important</tt>, and many
1106 of them will be tagged <tt>essential</tt> (see below).
1111 <heading>Essential packages</heading>
1114 Some packages are tagged <tt>essential</tt> for a system
1115 using the <tt>Essential</tt> control file field.
1116 The format of the <tt>Essential</tt> control field is
1117 described in <ref id="f-Essential">.
1121 Since these packages cannot be easily removed (one has to
1122 specify an extra <em>force option</em> to
1123 <prgn>dpkg</prgn> to do so), this flag must not be used
1124 unless absolutely necessary. A shared library package
1125 must not be tagged <tt>essential</tt>; dependencies will
1126 prevent its premature removal, and we need to be able to
1127 remove it when it has been superseded.
1131 Since dpkg will not prevent upgrading of other packages
1132 while an <tt>essential</tt> package is in an unconfigured
1133 state, all <tt>essential</tt> packages must supply all of
1134 their core functionality even when unconfigured. If the
1135 package cannot satisfy this requirement it must not be
1136 tagged as essential, and any packages depending on this
1137 package must instead have explicit dependency fields as
1142 You must not tag any packages <tt>essential</tt> before
1143 this has been discussed on the <tt>debian-devel</tt>
1144 mailing list and a consensus about doing that has been
1150 <heading>Tasks</heading>
1153 The Debian install process allows the user to choose from
1154 a number of common tasks which a Debian system can be used to
1155 perform. Selecting a task with <prgn>tasksel</prgn> causes
1156 a set of packages that are useful in performing that task to be
1161 This set of packages is all available packages which have the
1162 name of the selected task in the <tt>Task</tt> field of their
1163 control file. The format of this field is a list of tasks,
1164 separated by commas.
1168 You should not tag any packages as belonging to a task
1169 before this has been discussed on the
1170 <em>debian-devel</em> mailing list and a consensus about
1171 doing that has been reached.
1175 For third parties (and historical reasons), tasksel also
1176 supports constructing tasks based on <em>task
1177 packages</em>. These are packages whose names begin with
1178 <em>task-</em>. Task packages should not be included in the
1183 <sect id="maintscripts">
1184 <heading>Maintainer Scripts</heading>
1187 The package installation scripts should avoid producing
1188 output which is unnecessary for the user to see and
1189 should rely on <prgn>dpkg</prgn> to stave off boredom on
1190 the part of a user installing many packages. This means,
1191 amongst other things, using the <tt>--quiet</tt> option on
1192 <prgn>install-info</prgn>.
1196 Errors which occur during the execution of an installation
1197 script must be checked and the installation must not
1198 continue after an error.
1202 Note that in general <ref id="scripts"> applies to package
1203 maintainer scripts, too.
1207 You should not use <prgn>dpkg-divert</prgn> on a file
1208 belonging to another package without consulting the
1209 maintainer of that package first.
1213 All packages which supply an instance of a common command
1214 name (or, in general, filename) should generally use
1215 <prgn>update-alternatives</prgn>, so that they may be
1216 installed together. If <prgn>update-alternatives</prgn>
1217 is not used, then each package must use
1218 <tt>Conflicts</tt> to ensure that other packages are
1219 de-installed. (In this case, it may be appropriate to
1220 specify a conflict against earlier versions of something
1221 that previously did not use
1222 <prgn>update-alternatives</prgn>; this is an exception to
1223 the usual rule that versioned conflicts should be
1227 <sect1 id="maintscriptprompt">
1228 <heading>Prompting in maintainer scripts</heading>
1230 Package maintainer scripts may prompt the user if
1231 necessary. Prompting should be done by communicating
1232 through a program, such as <prgn>debconf</prgn>, which
1233 conforms to the Debian Configuration management
1234 specification, version 2 or higher. Prompting the user by
1235 other means, such as by hand<footnote>
1236 From the Jargon file: by hand 2. By extension,
1237 writing code which does something in an explicit or
1238 low-level way for which a presupplied library
1239 (<em>debconf, in this instance</em>) routine ought
1240 to have been available.
1241 </footnote>, is now deprecated.
1245 The Debian Configuration management specification is included
1246 in the <file>debconf_specification</file> files in the
1247 <package>debian-policy</package> package.
1248 It is also available from the Debian web mirrors at
1249 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1250 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1254 Packages which use the Debian Configuration management
1255 specification may contain an additional
1256 <prgn>config</prgn> script and a <tt>templates</tt>
1257 file in their control archive<footnote>
1258 The control.tar.gz inside the .deb.
1259 See <manref name="deb" section="5">.
1261 The <prgn>config</prgn> script might be run before the
1262 <prgn>preinst</prgn> script, and before the package is unpacked
1263 or any of its dependencies or pre-dependancies are satisfied.
1264 Therefore it must work using only the tools present in
1265 <em>essential</em> packages.<footnote>
1266 <package>Debconf</package> or another tool that
1267 implements the Debian Configuration management
1268 specification will also be installed, and any
1269 versioned dependencies on it will be satisfied
1270 before preconfiguration begins.
1275 Packages should try to minimize the amount of prompting
1276 they need to do, and they should ensure that the user
1277 will only ever be asked each question once. This means
1278 that packages should try to use appropriate shared
1279 configuration files (such as <file>/etc/papersize</file> and
1280 <file>/etc/news/server</file>), and shared
1281 <package>debconf</package> variables rather than each
1282 prompting for their own list of required pieces of
1287 It also means that an upgrade should not ask the same
1288 questions again, unless the user has used
1289 <tt>dpkg --purge</tt> to remove the package's configuration.
1290 The answers to configuration questions should be stored in an
1291 appropriate place in <file>/etc</file> so that the user can
1292 modify them, and how this has been done should be
1297 If a package has a vitally important piece of
1298 information to pass to the user (such as "don't run me
1299 as I am, you must edit the following configuration files
1300 first or you risk your system emitting badly-formatted
1301 messages"), it should display this in the
1302 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1303 prompt the user to hit return to acknowledge the
1304 message. Copyright messages do not count as vitally
1305 important (they belong in
1306 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1307 neither do instructions on how to use a program (these
1308 should be in on-line documentation, where all the users
1313 Any necessary prompting should almost always be confined
1314 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1315 script. If it is done in the <prgn>postinst</prgn>, it
1316 should be protected with a conditional so that
1317 unnecessary prompting doesn't happen if a package's
1318 installation fails and the <prgn>postinst</prgn> is
1319 called with <tt>abort-upgrade</tt>,
1320 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1330 <heading>Source packages</heading>
1332 <sect id="standardsversion">
1333 <heading>Standards conformance</heading>
1336 Source packages should specify the most recent version number
1337 of this policy document with which your package complied
1338 when it was last updated.
1342 This information may be used to file bug reports
1343 automatically if your package becomes too much out of date.
1347 The version is specified in the <tt>Standards-Version</tt>
1349 The format of the <tt>Standards-Version</tt> field is
1350 described in <ref id="f-Standards-Version">.
1354 You should regularly, and especially if your package has
1355 become out of date, check for the newest Policy Manual
1356 available and update your package, if necessary. When your
1357 package complies with the new standards you should update the
1358 <tt>Standards-Version</tt> source package field and
1359 release it.<footnote>
1360 See the file <file>upgrading-checklist</file> for
1361 information about policy which has changed between
1362 different versions of this document.
1368 <sect id="pkg-relations">
1369 <heading>Package relationships</heading>
1372 Source packages should specify which binary packages they
1373 require to be installed or not to be installed in order to
1374 build correctly. For example, if building a package
1375 requires a certain compiler, then the compiler should be
1376 specified as a build-time dependency.
1380 It is not necessary to explicitly specify build-time
1381 relationships on a minimal set of packages that are always
1382 needed to compile, link and put in a Debian package a
1383 standard "Hello World!" program written in C or C++. The
1384 required packages are called <em>build-essential</em>, and
1385 an informational list can be found in
1386 <file>/usr/share/doc/build-essential/list</file> (which is
1387 contained in the <tt>build-essential</tt>
1390 <list compact="compact">
1392 This allows maintaining the list separately
1393 from the policy documents (the list does not
1394 need the kind of control that the policy
1398 Having a separate package allows one to install
1399 the build-essential packages on a machine, as
1400 well as allowing other packages such as tasks to
1401 require installation of the build-essential
1402 packages using the depends relation.
1405 The separate package allows bug reports against
1406 the list to be categorized separately from
1407 the policy management process in the BTS.
1414 When specifying the set of build-time dependencies, one
1415 should list only those packages explicitly required by the
1416 build. It is not necessary to list packages which are
1417 required merely because some other package in the list of
1418 build-time dependencies depends on them.<footnote>
1419 The reason for this is that dependencies change, and
1420 you should list all those packages, and <em>only</em>
1421 those packages that <em>you</em> need directly. What
1422 others need is their business. For example, if you
1423 only link against <file>libimlib</file>, you will need to
1424 build-depend on <package>libimlib2-dev</package> but
1425 not against any <tt>libjpeg*</tt> packages, even
1426 though <tt>libimlib2-dev</tt> currently depends on
1427 them: installation of <package>libimlib2-dev</package>
1428 will automatically ensure that all of its run-time
1429 dependencies are satisfied.
1434 If build-time dependencies are specified, it must be
1435 possible to build the package and produce working binaries
1436 on a system with only essential and build-essential
1437 packages installed and also those required to satisfy the
1438 build-time relationships (including any implied
1439 relationships). In particular, this means that version
1440 clauses should be used rigorously in build-time
1441 relationships so that one cannot produce bad or
1442 inconsistently configured packages when the relationships
1443 are properly satisfied.
1447 <ref id="relationships"> explains the technical details.
1452 <heading>Changes to the upstream sources</heading>
1455 If changes to the source code are made that are not
1456 specific to the needs of the Debian system, they should be
1457 sent to the upstream authors in whatever form they prefer
1458 so as to be included in the upstream version of the
1463 If you need to configure the package differently for
1464 Debian or for Linux, and the upstream source doesn't
1465 provide a way to do so, you should add such configuration
1466 facilities (for example, a new <prgn>autoconf</prgn> test
1467 or <tt>#define</tt>) and send the patch to the upstream
1468 authors, with the default set to the way they originally
1469 had it. You can then easily override the default in your
1470 <file>debian/rules</file> or wherever is appropriate.
1474 You should make sure that the <prgn>configure</prgn> utility
1475 detects the correct architecture specification string
1476 (refer to <ref id="arch-spec"> for details).
1480 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1481 <prgn>configure</prgn> scripts are used, you should edit the
1482 <file>.in</file> files rather than editing the
1483 <prgn>Makefile</prgn> directly. This allows the user to
1484 reconfigure the package if necessary. You should
1485 <em>not</em> configure the package and edit the generated
1486 <prgn>Makefile</prgn>! This makes it impossible for someone
1487 else to later reconfigure the package without losing the
1493 <sect id="dpkgchangelog">
1494 <heading>Debian changelog: <file>debian/changelog</file></heading>
1497 Changes in the Debian version of the package should be
1498 briefly explained in the Debian changelog file
1499 <file>debian/changelog</file>.<footnote>
1501 Mistakes in changelogs are usually best rectified by
1502 making a new changelog entry rather than "rewriting
1503 history" by editing old changelog entries.
1506 This includes modifications
1507 made in the Debian package compared to the upstream one
1508 as well as other changes and updates to the package.
1510 Although there is nothing stopping an author who is also
1511 the Debian maintainer from using this changelog for all
1512 their changes, it will have to be renamed if the Debian
1513 and upstream maintainers become different people. In such
1514 a case, however, it might be better to maintain the package
1515 as a non-native package.
1524 The format of the <file>debian/changelog</file> allows the
1525 package building tools to discover which version of the package
1526 is being built and find out other release-specific information.
1530 That format is a series of entries like this:
1532 <example compact="compact">
1533 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1535 [optional blank line(s), stripped]
1537 * <var>change details</var>
1538 <var>more change details</var>
1540 [blank line(s), included in output of dpkg-parsechangelog]
1542 * <var>even more change details</var>
1544 [optional blank line(s), stripped]
1546 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1551 <var>package</var> and <var>version</var> are the source
1552 package name and version number.
1556 <var>distribution(s)</var> lists the distributions where
1557 this version should be installed when it is uploaded - it
1558 is copied to the <tt>Distribution</tt> field in the
1559 <file>.changes</file> file. See <ref id="f-Distribution">.
1563 <var>urgency</var> is the value for the <tt>Urgency</tt>
1564 field in the <file>.changes</file> file for the upload
1565 (see <ref id="f-Urgency">). It is not possible to specify
1566 an urgency containing commas; commas are used to separate
1567 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1568 <prgn>dpkg</prgn> changelog format (though there is
1569 currently only one useful <var>keyword</var>,
1570 <tt>urgency</tt>).<footnote>
1571 Recognised urgency values are <tt>low</tt>,
1572 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1573 They have an effect on how quickly a package will be
1574 considered for inclusion into the <tt>testing</tt>
1575 distribution, and give an indication of the importance
1576 of any fixes included in this upload.
1581 The change details may in fact be any series of lines
1582 starting with at least two spaces, but conventionally each
1583 change starts with an asterisk and a separating space and
1584 continuation lines are indented so as to bring them in
1585 line with the start of the text above. Blank lines may be
1586 used here to separate groups of changes, if desired.
1590 If this upload resolves bugs recorded in the Bug Tracking
1591 System (BTS), they may be automatically closed on the
1592 inclusion of this package into the Debian archive by
1593 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1594 in the change details.<footnote>
1595 To be precise, the string should match the following
1596 Perl regular expression:
1598 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1600 Then all of the bug numbers listed will be closed by the
1601 archive maintenance script (<prgn>katie</prgn>), or in
1602 the case of an NMU, marked as fixed.
1604 This information is conveyed via the <tt>Closes</tt> field
1605 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1609 The maintainer name and email address used in the changelog
1610 should be the details of the person uploading <em>this</em>
1611 version. They are <em>not</em> necessarily those of the
1612 usual package maintainer. The information here will be
1613 copied to the <tt>Changed-By</tt> field in the
1614 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1615 and then later used to send an acknowledgement when the
1616 upload has been installed.
1620 The <var>date</var> should be in RFC822 format<footnote>
1621 This is generated by the <prgn>822-date</prgn>
1623 </footnote>; it should include the time zone specified
1624 numerically, with the time zone name or abbreviation
1625 optionally present as a comment in parentheses.
1629 The first "title" line with the package name should start
1630 at the left hand margin; the "trailer" line with the
1631 maintainer and date details should be preceded by exactly
1632 one space. The maintainer details and the date must be
1633 separated by exactly two spaces.
1637 For more information on placement of the changelog files
1638 within binary packages, please see <ref id="changelogs">.
1641 <sect1><heading>Alternative changelog formats</heading>
1644 In non-experimental packages you must use a format for
1645 <file>debian/changelog</file> which is supported by the most
1646 recent released version of <prgn>dpkg</prgn>.
1650 It is possible to use a format different from the standard
1651 one by providing a changelog parser for the format you wish
1652 to use. The parser must have an API compatible with that
1653 expected by <prgn>dpkg-genchanges</prgn> and
1654 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1657 If there is general interest in the new format, you should
1658 contact the <package>dpkg</package> maintainer to have the
1659 parser script for it included in the <prgn>dpkg</prgn>
1660 package. (You will need to agree that the parser and its
1661 man page may be distributed under the GNU GPL, just as the rest
1662 of <prgn>dpkg</prgn> is.)
1669 <heading>Error trapping in makefiles</heading>
1672 When <prgn>make</prgn> invokes a command in a makefile
1673 (including your package's upstream makefiles and
1674 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1675 means that <prgn>sh</prgn>'s usual bad error handling
1676 properties apply: if you include a miniature script as one
1677 of the commands in your makefile you'll find that if you
1678 don't do anything about it then errors are not detected
1679 and <prgn>make</prgn> will blithely continue after
1684 Every time you put more than one shell command (this
1685 includes using a loop) in a makefile command you
1686 must make sure that errors are trapped. For
1687 simple compound commands, such as changing directory and
1688 then running a program, using <tt>&&</tt> rather
1689 than semicolon as a command separator is sufficient. For
1690 more complex commands including most loops and
1691 conditionals you should include a separate <tt>set -e</tt>
1692 command at the start of every makefile command that's
1693 actually one of these miniature shell scripts.
1697 <sect id="timestamps">
1698 <heading>Time Stamps</heading>
1700 Maintainers should preserve the modification times of the
1701 upstream source files in a package, as far as is reasonably
1703 The rationale is that there is some information conveyed
1704 by knowing the age of the file, for example, you could
1705 recognize that some documentation is very old by looking
1706 at the modification time, so it would be nice if the
1707 modification time of the upstream source would be
1713 <sect id="restrictions">
1714 <heading>Restrictions on objects in source packages</heading>
1717 The source package may not contain any hard links<footnote>
1719 This is not currently detected when building source
1720 packages, but only when extracting
1724 Hard links may be permitted at some point in the
1725 future, but would require a fair amount of
1728 </footnote>, device special files, sockets or setuid or
1729 setgid files.<footnote>
1730 Setgid directories are allowed.
1735 <sect id="debianrules">
1736 <heading>Main building script: <file>debian/rules</file></heading>
1739 This file must be an executable makefile, and contains the
1740 package-specific recipes for compiling the package and
1741 building binary package(s) from the source.
1745 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1746 so that it can be invoked by saying its name rather than
1747 invoking <prgn>make</prgn> explicitly.
1751 Since an interactive <file>debian/rules</file> script makes it
1752 impossible to auto-compile that package and also makes it
1753 hard for other people to reproduce the same binary
1754 package, all <em>required targets</em> MUST be
1755 non-interactive. At a minimum, required targets are the
1756 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1757 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1758 <em>binary-indep</em>, and <em>build</em>. It also follows
1759 that any target that these targets depend on must also be
1764 The targets are as follows (required unless stated otherwise):
1766 <tag><tt>build</tt></tag>
1769 The <tt>build</tt> target should perform all the
1770 configuration and compilation of the package.
1771 If a package has an interactive pre-build
1772 configuration routine, the Debianized source package
1773 must either be built after this has taken place (so
1774 that the binary package can be built without rerunning
1775 the configuration) or the configuration routine
1776 modified to become non-interactive. (The latter is
1777 preferable if there are architecture-specific features
1778 detected by the configuration routine.)
1782 For some packages, notably ones where the same
1783 source tree is compiled in different ways to produce
1784 two binary packages, the <tt>build</tt> target
1785 does not make much sense. For these packages it is
1786 good enough to provide two (or more) targets
1787 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1788 for each of the ways of building the package, and a
1789 <tt>build</tt> target that does nothing. The
1790 <tt>binary</tt> target will have to build the
1791 package in each of the possible ways and make the
1792 binary package out of each.
1796 The <tt>build</tt> target must not do anything
1797 that might require root privilege.
1801 The <tt>build</tt> target may need to run the
1802 <tt>clean</tt> target first - see below.
1806 When a package has a configuration and build routine
1807 which takes a long time, or when the makefiles are
1808 poorly designed, or when <tt>build</tt> needs to
1809 run <tt>clean</tt> first, it is a good idea to
1810 <tt>touch build</tt> when the build process is
1811 complete. This will ensure that if <tt>debian/rules
1812 build</tt> is run again it will not rebuild the whole
1814 Another common way to do this is for <tt>build</tt>
1815 to depend on <prgn>build-stamp</prgn> and to do
1816 nothing else, and for the <prgn>build-stamp</prgn>
1817 target to do the building and to <tt>touch
1818 build-stamp</tt> on completion. This is
1819 especially useful if the build routine creates a
1820 file or directory called <tt>build</tt>; in such a
1821 case, <tt>build</tt> will need to be listed as
1822 a phony target (i.e., as a dependency of the
1823 <tt>.PHONY</tt> target). See the documentation of
1824 <prgn>make</prgn> for more information on phony
1830 <tag><tt>build-arch</tt> (optional),
1831 <tt>build-indep</tt> (optional)
1835 A package may also provide both of the targets
1836 <tt>build-arch</tt> and <tt>build-indep</tt>.
1837 The <tt>build-arch</tt> target, if provided, should
1838 perform all the configuration and compilation required
1839 for producing all architecture-dependant binary packages
1840 (those packages for which the body of the
1841 <tt>Architecture</tt> field in <tt>debian/control</tt>
1842 is not <tt>all</tt>).
1843 Similarly, the <tt>build-indep</tt> target, if
1844 provided, should perform all the configuration and
1845 compilation required for producing all
1846 architecture-independent binary packages
1847 (those packages for which the body of the
1848 <tt>Architecture</tt> field in <tt>debian/control</tt>
1850 The <tt>build</tt> target should depend on those of the
1851 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1852 are provided in the rules file.
1856 If one or both of the targets <tt>build-arch</tt> and
1857 <tt>build-indep</tt> are not provided, then invoking
1858 <file>debian/rules</file> with one of the not-provided
1859 targets as arguments should produce a exit status code
1860 of 2. Usually this is provided automatically by make
1861 if the target is missing.
1865 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1866 must not do anything that might require root privilege.
1870 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1871 <tt>binary-indep</tt>
1875 The <tt>binary</tt> target must be all that is
1876 necessary for the user to build the binary package(s)
1877 produced from this source package. It is
1878 split into two parts: <prgn>binary-arch</prgn> builds
1879 the binary packages which are specific to a particular
1880 architecture, and <tt>binary-indep</tt> builds
1881 those which are not.
1884 <tt>binary</tt> may be (and commonly is) a target with
1885 no commands which simply depends on
1886 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1889 Both <tt>binary-*</tt> targets should depend on the
1890 <tt>build</tt> target, or on the appropriate
1891 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1892 provided, so that the package is built if it has not
1893 been already. It should then create the relevant
1894 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1895 make their control files and <prgn>dpkg-deb</prgn> to
1896 build them and place them in the parent of the top
1901 Both the <tt>binary-arch</tt> and
1902 <tt>binary-indep</tt> targets <em>must</em> exist.
1903 If one of them has nothing to do (which will always be
1904 the case if the source generates only a single binary
1905 package, whether architecture-dependent or not), it
1906 must still exist and must always succeed.
1910 The <tt>binary</tt> targets must be invoked as
1912 The <prgn>fakeroot</prgn> package often allows one
1913 to build a package correctly even without being
1919 <tag><tt>clean</tt></tag>
1922 This must undo any effects that the <tt>build</tt>
1923 and <tt>binary</tt> targets may have had, except
1924 that it should leave alone any output files created in
1925 the parent directory by a run of a <tt>binary</tt>
1930 If a <tt>build</tt> file is touched at the end of
1931 the <tt>build</tt> target, as suggested above, it
1932 should be removed as the first action that
1933 <tt>clean</tt> performs, so that running
1934 <tt>build</tt> again after an interrupted
1935 <tt>clean</tt> doesn't think that everything is
1940 The <tt>clean</tt> target may need to be
1941 invoked as root if <tt>binary</tt> has been
1942 invoked since the last <tt>clean</tt>, or if
1943 <tt>build</tt> has been invoked as root (since
1944 <tt>build</tt> may create directories, for
1949 <tag><tt>get-orig-source</tt> (optional)</tag>
1952 This target fetches the most recent version of the
1953 original source package from a canonical archive site
1954 (via FTP or WWW, for example), does any necessary
1955 rearrangement to turn it into the original source
1956 tar file format described below, and leaves it in the
1961 This target may be invoked in any directory, and
1962 should take care to clean up any temporary files it
1967 This target is optional, but providing it if
1968 possible is a good idea.
1974 The <tt>build</tt>, <tt>binary</tt> and
1975 <tt>clean</tt> targets must be invoked with the current
1976 directory being the package's top-level directory.
1981 Additional targets may exist in <file>debian/rules</file>,
1982 either as published or undocumented interfaces or for the
1983 package's internal use.
1987 The architectures we build on and build for are determined
1988 by <prgn>make</prgn> variables using the utility
1989 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1990 You can determine the
1991 Debian architecture and the GNU style architecture
1992 specification string for the build machine (the machine type
1993 we are building on) as well as for the host machine (the
1994 machine type we are building for). Here is a list of
1995 supported <prgn>make</prgn> variables:
1996 <list compact="compact">
1998 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2001 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2002 specification string)
2005 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2006 <tt>DEB_*_GNU_TYPE</tt>)
2009 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2010 <tt>DEB_*_GNU_TYPE</tt>)
2012 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2013 the build machine or <tt>HOST</tt> for specification of the
2018 Backward compatibility can be provided in the rules file
2019 by setting the needed variables to suitable default
2020 values; please refer to the documentation of
2021 <prgn>dpkg-architecture</prgn> for details.
2025 It is important to understand that the <tt>DEB_*_ARCH</tt>
2026 string only determines which Debian architecture we are
2027 building on or for. It should not be used to get the CPU
2028 or system information; the GNU style variables should be
2033 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2034 <sect id="substvars">
2035 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2038 When <prgn>dpkg-gencontrol</prgn>,
2039 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2040 generate control files they perform variable substitutions
2041 on their output just before writing it. Variable
2042 substitutions have the form <tt>${<var>variable</var>}</tt>.
2043 The optional file <file>debian/substvars</file> contains
2044 variable substitutions to be used; variables can also be set
2045 directly from <file>debian/rules</file> using the <tt>-V</tt>
2046 option to the source packaging commands, and certain
2047 predefined variables are also available.
2051 The <file>debian/substvars</file> file is usually generated and
2052 modified dynamically by <file>debian/rules</file> targets, in
2053 which case it must be removed by the <tt>clean</tt> target.
2057 See <manref name="dpkg-source" section="1"> for full
2058 details about source variable substitutions, including the
2059 format of <file>debian/substvars</file>.</p>
2062 <sect id="debianfiles">
2063 <heading>Generated files list: <file>debian/files</file></heading>
2066 This file is not a permanent part of the source tree; it
2067 is used while building packages to record which files are
2068 being generated. <prgn>dpkg-genchanges</prgn> uses it
2069 when it generates a <file>.changes</file> file.
2073 It should not exist in a shipped source package, and so it
2074 (and any backup files or temporary files such as
2075 <file>files.new</file><footnote>
2076 <file>files.new</file> is used as a temporary file by
2077 <prgn>dpkg-gencontrol</prgn> and
2078 <prgn>dpkg-distaddfile</prgn> - they write a new
2079 version of <tt>files</tt> here before renaming it,
2080 to avoid leaving a corrupted copy if an error
2082 </footnote>) should be removed by the
2083 <tt>clean</tt> target. It may also be wise to
2084 ensure a fresh start by emptying or removing it at the
2085 start of the <tt>binary</tt> target.
2089 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2090 package, it adds an entry to <file>debian/files</file> for the
2091 <file>.deb</file> file that will be created when <tt>dpkg-deb
2092 --build</tt> is run for that binary package. So for most
2093 packages all that needs to be done with this file is to
2094 delete it in the <tt>clean</tt> target.
2098 If a package upload includes files besides the source
2099 package and any binary packages whose control files were
2100 made with <prgn>dpkg-gencontrol</prgn> then they should be
2101 placed in the parent of the package's top-level directory
2102 and <prgn>dpkg-distaddfile</prgn> should be called to add
2103 the file to the list in <file>debian/files</file>.</p>
2109 <chapt id="controlfields">
2110 <heading>Control files and their fields</heading>
2113 The package management system manipulates data represented in
2114 a common format, known as <em>control data</em>, stored in
2115 <em>control files</em>.
2116 Control files are used for source packages, binary packages and
2117 the <file>.changes</file> files which control the installation
2118 of uploaded files<footnote>
2119 <prgn>dpkg</prgn>'s internal databases are in a similar
2124 <sect id="controlsyntax">
2125 <heading>Syntax of control files</heading>
2128 A control file consists of one or more paragraphs of
2130 The paragraphs are also sometimes referred to as stanzas.
2132 The paragraphs are separated by blank lines. Some control
2133 files allow only one paragraph; others allow several, in
2134 which case each paragraph usually refers to a different
2135 package. (For example, in source packages, the first
2136 paragraph refers to the source package, and later paragraphs
2137 refer to binary packages generated from the source.)
2141 Each paragraph consists of a series of data fields; each
2142 field consists of the field name, followed by a colon and
2143 then the data/value associated with that field. It ends at
2144 the end of the line. Horizontal whitespace (spaces and
2145 tabs) may occur immediately before or after the value and is
2146 ignored there; it is conventional to put a single space
2147 after the colon. For example, a field might be:
2148 <example compact="compact">
2151 the field name is <tt>Package</tt> and the field value
2156 Some fields' values may span several lines; in this case
2157 each continuation line must start with a space or a tab.
2158 Any trailing spaces or tabs at the end of individual
2159 lines of a field value are ignored.
2163 Except where otherwise stated, only a single line of data is
2164 allowed and whitespace is not significant in a field body.
2165 Whitespace must not appear inside names (of packages,
2166 architectures, files or anything else) or version numbers,
2167 or between the characters of multi-character version
2172 Field names are not case-sensitive, but it is usual to
2173 capitalize the field names using mixed case as shown below.
2177 Blank lines, or lines consisting only of spaces and tabs,
2178 are not allowed within field values or between fields - that
2179 would mean a new paragraph.
2184 <sect id="sourcecontrolfiles">
2185 <heading>Source package control files -- <file>debian/control</file></heading>
2188 The <file>debian/control</file> file contains the most vital
2189 (and version-independent) information about the source package
2190 and about the binary packages it creates.
2194 The first paragraph of the control file contains information about
2195 the source package in general. The subsequent sets each describe a
2196 binary package that the source tree builds.
2200 The fields in the general paragraph (the first one, for the source
2203 <list compact="compact">
2204 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2205 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2206 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2207 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2208 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2209 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2210 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2215 The fields in the binary package paragraphs are:
2217 <list compact="compact">
2218 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2219 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2220 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2221 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2222 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2223 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2224 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2229 The syntax and semantics of the fields are described below.
2235 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2236 generate control files for binary packages (see below), by
2237 <prgn>dpkg-genchanges</prgn> to generate the
2238 <tt>.changes</tt> file to accompany the upload, and by
2239 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2240 source control file as part of a source archive.
2244 The fields here may contain variable references - their
2245 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2246 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2247 when they generate output control files.
2248 See <ref id="substvars"> for details.
2253 <sect id="binarycontrolfiles">
2254 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2257 The <file>DEBIAN/control</file> file contains the most vital
2258 (and version-dependent) information about a binary package.
2262 The fields in this file are:
2264 <list compact="compact">
2265 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2266 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2267 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2268 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2269 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2270 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2271 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2272 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2273 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2274 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2275 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2280 <sect id="debiansourcecontrolfiles">
2281 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2284 This file contains a series of fields, identified and
2285 separated just like the fields in the control file of
2286 a binary package. The fields are listed below; their
2287 syntax is described above, in <ref id="pkg-controlfields">.
2289 <list compact="compact">
2290 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2291 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2292 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2293 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2294 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2295 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2296 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2297 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2298 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2299 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2304 The source package control file is generated by
2305 <prgn>dpkg-source</prgn> when it builds the source
2306 archive, from other files in the source package,
2307 described above. When unpacking, it is checked against
2308 the files and directories in the other parts of the
2314 <sect id="debianchangesfiles">
2315 <heading>Debian changes files -- <file>.changes</file></heading>
2318 The .changes files are used by the Debian archive maintenance
2319 software to process updates to packages. They contain one
2320 paragraph which contains information from the
2321 <tt>debian/control</tt> file and other data about the
2322 source package gathered via <tt>debian/changelog</tt>
2323 and <tt>debian/rules</tt>.
2327 The fields in this file are:
2329 <list compact="compact">
2330 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2333 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2335 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2337 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2338 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2339 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2340 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2341 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2342 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2343 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2348 <sect id="controlfieldslist">
2349 <heading>List of fields</heading>
2351 <sect1 id="f-Source">
2352 <heading><tt>Source</tt></heading>
2355 This field identifies the source package name.
2359 In a main source control information, a <file>.changes</file>
2360 or a <file>.dsc</file> file this may contain only the name
2361 of the source package.
2365 In the control file of a binary package it may be followed
2366 by a version number in parentheses<footnote>
2367 It is customary to leave a space after the package name
2368 if a version number is specified.
2370 This version number may be omitted (and is, by
2371 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2372 the <tt>Version</tt> field of the binary package in
2373 question. The field itself may be omitted from a binary
2374 package control file when the source package has the same
2375 name and version as the binary package.
2379 <sect1 id="f-Maintainer">
2380 <heading><tt>Maintainer</tt></heading>
2383 The package maintainer's name and email address. The name
2384 should come first, then the email address inside angle
2385 brackets <tt><></tt> (in RFC822 format).
2389 If the maintainer's name contains a full stop then the
2390 whole field will not work directly as an email address due
2391 to a misfeature in the syntax specified in RFC822; a
2392 program using this field as an address must check for this
2393 and correct the problem if necessary (for example by
2394 putting the name in round brackets and moving it to the
2395 end, and bringing the email address forward).
2399 <sect1 id="f-Uploaders">
2400 <heading><tt>Uploaders</tt></heading>
2403 List of the names and email addresses of
2404 co-maintaintainers of the package, if any. If the package
2405 has other maintainers beside the one named in the <qref
2406 id="f-Maintainer">Maintainer field</qref>, they their
2407 names and email addresses should be listed here. The
2408 format is the same as that of the Maintainer tag, and
2409 multiple entries should be comma separated. This is an
2414 <sect1 id="f-Changed-By">
2415 <heading><tt>Changed-By</tt></heading>
2418 The name and email address of the person who changed the
2419 said package. Usually the name of the maintainer.
2420 All the rules for the Maintainer field apply here, too.
2424 <sect1 id="f-Section">
2425 <heading><tt>Section</tt></heading>
2428 This field specifies an application area into which the package
2429 has been classified. See <ref id="subsections">.
2433 When it appears in the <file>debian/control</file> file,
2434 it gives the value for the subfield of the same name in
2435 the <tt>Files</tt> field of the <file>.changes</file> file.
2436 It also gives the default for the same field in the binary
2441 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2442 field in the control file of a binary package - use the
2443 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2447 <sect1 id="f-Priority">
2448 <heading><tt>Priority</tt></heading>
2451 This field represents how important that it is that the user
2452 have the package installed. See <ref id="priorities">.
2456 When it appears in the <file>debian/control</file> file,
2457 it gives the value for the subfield of the same name in
2458 the <tt>Files</tt> field of the <file>.changes</file> file.
2459 It also gives the default for the same field in the binary
2464 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2465 field in the control file of a binary package - use the
2466 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2470 <sect1 id="f-Package">
2471 <heading><tt>Package</tt></heading>
2474 The name of the binary package.
2478 Package names must consist only of lower case letters
2479 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2480 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2481 They must be at least two characters long and must start
2482 with an alphanumeric character.
2486 <sect1 id="f-Architecture">
2487 <heading><tt>Architecture</tt></heading>
2490 Depending on context and the control file used, the
2491 <tt>Architecture</tt> field can include the following sets of
2494 <item>A unique single word identifying a Debian machine
2495 architecture, see <ref id="arch-spec">.
2496 <item><tt>all</tt>, which indicates an
2497 architecture-independent package.
2498 <item><tt>any</tt>, which indicates a package available
2499 for building on any architecture.
2500 <item><tt>source</tt>, which indicates a source package.
2505 In the main <file>debian/control</file> file in the source
2506 package, or in the source package control file
2507 <file>.dsc</file>, one may specify a list of architectures
2508 separated by spaces, or the special values <tt>any</tt> or
2513 Specifying <tt>any</tt> indicates that the source package
2514 isn't dependent on any particular architecture and should
2515 compile fine on any one. The produced binary package(s)
2516 will be specific to whatever the current build architecture
2518 This is the most often used setting, and is recommended
2519 for new packages that aren't <tt>Architecture: all</tt>.
2524 Specifying a list of architectures indicates that the source
2525 will build an architecture-dependent package, and will only
2526 work correctly on the listed architectures.<footnote>
2527 This is a setting used for a minority of cases where the
2528 program is not portable. Generally, it should not be used
2534 In a <file>.changes</file> file, the <tt>Architecture</tt>
2535 field lists the architecture(s) of the package(s)
2536 currently being uploaded. This will be a list; if the
2537 source for the package is also being uploaded, the special
2538 entry <tt>source</tt> is also present.
2542 See <ref id="debianrules"> for information how to get the
2543 architecture for the build process.
2547 <sect1 id="f-Essential">
2548 <heading><tt>Essential</tt></heading>
2551 This is a boolean field which may occur only in the
2552 control file of a binary package or in a per-package fields
2553 paragraph of a main source control data file.
2557 If set to <tt>yes</tt> then the package management system
2558 will refuse to remove the package (upgrading and replacing
2559 it is still possible). The other possible value is <tt>no</tt>,
2560 which is the same as not having the field at all.
2565 <heading>Package interrelationship fields:
2566 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2567 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2568 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2572 These fields describe the package's relationships with
2573 other packages. Their syntax and semantics are described
2574 in <ref id="relationships">.</p>
2577 <sect1 id="f-Standards-Version">
2578 <heading><tt>Standards-Version</tt></heading>
2581 The most recent version of the standards (the policy
2582 manual and associated texts) with which the package
2587 The version number has four components: major and minor
2588 version number and major and minor patch level. When the
2589 standards change in a way that requires every package to
2590 change the major number will be changed. Significant
2591 changes that will require work in many packages will be
2592 signaled by a change to the minor number. The major patch
2593 level will be changed for any change to the meaning of the
2594 standards, however small; the minor patch level will be
2595 changed when only cosmetic, typographical or other edits
2596 are made which neither change the meaning of the document
2597 nor affect the contents of packages.
2601 Thus only the first three components of the policy version
2602 are significant in the <em>Standards-Version</em> control
2603 field, and so either these three components or the all
2604 four components may be specified.<footnote>
2605 In the past, people specified the full version number
2606 in the Standards-Version field, for example "2.3.0.0".
2607 Since minor patch-level changes don't introduce new
2608 policy, it was thought it would be better to relax
2609 policy and only require the first 3 components to be
2610 specified, in this example "2.3.0". All four
2611 components may still be used if someone wishes to do so.
2617 <sect1 id="f-Version">
2618 <heading><tt>Version</tt></heading>
2621 The version number of a package. The format is:
2622 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2626 The three components here are:
2628 <tag><var>epoch</var></tag>
2631 This is a single (generally small) unsigned integer. It
2632 may be omitted, in which case zero is assumed. If it is
2633 omitted then the <var>upstream_version</var> may not
2638 It is provided to allow mistakes in the version numbers
2639 of older versions of a package, and also a package's
2640 previous version numbering schemes, to be left behind.
2644 <tag><var>upstream_version</var></tag>
2647 This is the main part of the version number. It is
2648 usually the version number of the original ("upstream")
2649 package from which the <file>.deb</file> file has been made,
2650 if this is applicable. Usually this will be in the same
2651 format as that specified by the upstream author(s);
2652 however, it may need to be reformatted to fit into the
2653 package management system's format and comparison
2658 The comparison behavior of the package management system
2659 with respect to the <var>upstream_version</var> is
2660 described below. The <var>upstream_version</var>
2661 portion of the version number is mandatory.
2665 The <var>upstream_version</var> may contain only
2666 alphanumerics<footnote>
2667 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2669 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2670 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2671 start with a digit. If there is no
2672 <var>debian_revision</var> then hyphens are not allowed;
2673 if there is no <var>epoch</var> then colons are not
2678 <tag><var>debian_revision</var></tag>
2681 This part of the version number specifies the version of
2682 the Debian package based on the upstream version. It
2683 may contain only alphanumerics and the characters
2684 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2685 compared in the same way as the
2686 <var>upstream_version</var> is.
2690 It is optional; if it isn't present then the
2691 <var>upstream_version</var> may not contain a hyphen.
2692 This format represents the case where a piece of
2693 software was written specifically to be turned into a
2694 Debian package, and so there is only one "debianization"
2695 of it and therefore no revision indication is required.
2699 It is conventional to restart the
2700 <var>debian_revision</var> at <tt>1</tt> each time the
2701 <var>upstream_version</var> is increased.
2705 The package management system will break the version
2706 number apart at the last hyphen in the string (if there
2707 is one) to determine the <var>upstream_version</var> and
2708 <var>debian_revision</var>. The absence of a
2709 <var>debian_revision</var> compares earlier than the
2710 presence of one (but note that the
2711 <var>debian_revision</var> is the least significant part
2712 of the version number).
2719 The <var>upstream_version</var> and <var>debian_revision</var>
2720 parts are compared by the package management system using the
2725 The strings are compared from left to right.
2729 First the initial part of each string consisting entirely of
2730 non-digit characters is determined. These two parts (one of
2731 which may be empty) are compared lexically. If a difference
2732 is found it is returned. The lexical comparison is a
2733 comparison of ASCII values modified so that all the letters
2734 sort earlier than all the non-letters.
2738 Then the initial part of the remainder of each string which
2739 consists entirely of digit characters is determined. The
2740 numerical values of these two parts are compared, and any
2741 difference found is returned as the result of the comparison.
2742 For these purposes an empty string (which can only occur at
2743 the end of one or both version strings being compared) counts
2748 These two steps (comparing and removing initial non-digit
2749 strings and initial digit strings) are repeated until a
2750 difference is found or both strings are exhausted.
2754 Note that the purpose of epochs is to allow us to leave behind
2755 mistakes in version numbering, and to cope with situations
2756 where the version numbering scheme changes. It is
2757 <em>not</em> intended to cope with version numbers containing
2758 strings of letters which the package management system cannot
2759 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2760 silly orderings (the author of this manual has heard of a
2761 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2762 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2763 <tt>2</tt> and so forth).
2767 <sect1 id="f-Description">
2768 <heading><tt>Description</tt></heading>
2771 In a source or binary control file, the <tt>Description</tt>
2772 field contains a description of the binary package, consisting
2773 of two parts, the synopsis or the short description, and the
2774 long description. The field's format is as follows:
2779 Description: <single line synopsis>
2780 <extended description over several lines>
2785 The lines in the extended description can have these formats:
2791 Those starting with a single space are part of a paragraph.
2792 Successive lines of this form will be word-wrapped when
2793 displayed. The leading space will usually be stripped off.
2797 Those starting with two or more spaces. These will be
2798 displayed verbatim. If the display cannot be panned
2799 horizontally, the displaying program will linewrap them "hard"
2800 (i.e., without taking account of word breaks). If it can they
2801 will be allowed to trail off to the right. None, one or two
2802 initial spaces may be deleted, but the number of spaces
2803 deleted from each line will be the same (so that you can have
2804 indenting work correctly, for example).
2808 Those containing a single space followed by a single full stop
2809 character. These are rendered as blank lines. This is the
2810 <em>only</em> way to get a blank line<footnote>
2811 Completely empty lines will not be rendered as blank lines.
2812 Instead, they will cause the parser to think you're starting
2813 a whole new record in the control file, and will therefore
2814 likely abort with an error.
2819 Those containing a space, a full stop and some more characters.
2820 These are for future expansion. Do not use them.
2826 Do not use tab characters. Their effect is not predictable.
2830 See <ref id="descriptions"> for further information on this.
2834 In a <file>.changes</file> file, the <tt>Description</tt> field
2835 contains a summary of the descriptions for the packages being
2840 The part of the field before the first newline is empty;
2841 thereafter each line has the name of a binary package and
2842 the summary description line from that binary package.
2843 Each line is indented by one space.
2848 <sect1 id="f-Distribution">
2849 <heading><tt>Distribution</tt></heading>
2852 In a <file>.changes</file> file or parsed changelog output
2853 this contains the (space-separated) name(s) of the
2854 distribution(s) where this version of the package should
2855 be installed. Valid distributions are determined by the
2856 archive maintainers.<footnote>
2857 Current distribution names are:
2858 <taglist compact="compact">
2859 <tag><em>stable</em></tag>
2861 This is the current "released" version of Debian
2862 GNU/Linux. Once the distribution is
2863 <em>stable</em> only security fixes and other
2864 major bug fixes are allowed. When changes are
2865 made to this distribution, the release number is
2866 increased (for example: 2.2r1 becomes 2.2r2 then
2870 <tag><em>unstable</em></tag>
2872 This distribution value refers to the
2873 <em>developmental</em> part of the Debian
2874 distribution tree. New packages, new upstream
2875 versions of packages and bug fixes go into the
2876 <em>unstable</em> directory tree. Download from
2877 this distribution at your own risk.
2880 <tag><em>testing</em></tag>
2882 This distribution value refers to the
2883 <em>testing</em> part of the Debian distribution
2884 tree. It receives its packages from the
2885 unstable distribution after a short time lag to
2886 ensure that there are no major issues with the
2887 unstable packages. It is less prone to breakage
2888 than unstable, but still risky. It is not
2889 possible to upload packages directly to
2893 <tag><em>frozen</em></tag>
2895 From time to time, the <em>testing</em>
2896 distribution enters a state of "code-freeze" in
2897 anticipation of release as a <em>stable</em>
2898 version. During this period of testing only
2899 fixes for existing or newly-discovered bugs will
2900 be allowed. The exact details of this stage are
2901 determined by the Release Manager.
2904 <tag><em>experimental</em></tag>
2906 The packages with this distribution value are
2907 deemed by their maintainers to be high
2908 risk. Oftentimes they represent early beta or
2909 developmental packages from various sources that
2910 the maintainers want people to try, but are not
2911 ready to be a part of the other parts of the
2912 Debian distribution tree. Download at your own
2918 You should list <em>all</em> distributions that the
2919 package should be installed into.
2923 More information is available in the Debian Developer's
2924 Reference, section "The Debian archive".
2931 <heading><tt>Date</tt></heading>
2934 This field includes the date the package was built or last edited.
2938 The value of this field is usually extracted from the
2939 <file>debian/changelog</file> file - see
2940 <ref id="dpkgchangelog">).
2944 <sect1 id="f-Format">
2945 <heading><tt>Format</tt></heading>
2948 This field specifies a format revision for the file.
2949 The most current format described in the Policy Manual
2950 is version <strong>1.5</strong>. The syntax of the
2951 format value is the same as that of a package version
2952 number except that no epoch or Debian revision is allowed
2953 - see <ref id="f-Version">.
2957 <sect1 id="f-Urgency">
2958 <heading><tt>Urgency</tt></heading>
2961 This is a description of how important it is to upgrade to
2962 this version from previous ones. It consists of a single
2963 keyword usually taking one of the values <tt>low</tt>,
2964 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2965 followed by an optional commentary (separated by a space)
2966 which is usually in parentheses. For example:
2969 Urgency: low (HIGH for users of diversions)
2975 The value of this field is usually extracted from the
2976 <file>debian/changelog</file> file - see
2977 <ref id="dpkgchangelog">.
2981 <sect1 id="f-Changes">
2982 <heading><tt>Changes</tt></heading>
2985 This field contains the human-readable changes data, describing
2986 the differences between the last version and the current one.
2990 There should be nothing in this field before the first
2991 newline; all the subsequent lines must be indented by at
2992 least one space; blank lines must be represented by a line
2993 consiting only of a space and a full stop.
2997 The value of this field is usually extracted from the
2998 <file>debian/changelog</file> file - see
2999 <ref id="dpkgchangelog">).
3003 Each version's change information should be preceded by a
3004 "title" line giving at least the version, distribution(s)
3005 and urgency, in a human-readable way.
3009 If data from several versions is being returned the entry
3010 for the most recent version should be returned first, and
3011 entries should be separated by the representation of a
3012 blank line (the "title" line may also be followed by the
3013 representation of blank line).
3017 <sect1 id="f-Binary">
3018 <heading><tt>Binary</tt></heading>
3021 This field is a list of binary packages.
3025 When it appears in the <file>.dsc</file> file it is the list
3026 of binary packages which a source package can produce. It
3027 does not necessarily produce all of these binary packages
3028 for every architecture. The source control file doesn't
3029 contain details of which architectures are appropriate for
3030 which of the binary packages.
3034 When it appears in a <file>.changes</file> file it lists the
3035 names of the binary packages actually being uploaded.
3039 The syntax is a list of binary packages separated by
3041 A space after each comma is conventional.
3042 </footnote>. Currently the packages must be separated using
3043 only spaces in the <file>.changes</file> file.
3047 <sect1 id="f-Installed-Size">
3048 <heading><tt>Installed-Size</tt></heading>
3051 This field appears in the control files of binary
3052 packages, and in the <file>Packages</file> files. It gives
3053 the total amount of disk space required to install the
3058 The disk space is represented in kilobytes as a simple
3063 <sect1 id="f-Files">
3064 <heading><tt>Files</tt></heading>
3067 This field contains a list of files with information about
3068 each one. The exact information and syntax varies with
3069 the context. In all cases the part of the field
3070 contents on the same line as the field name is empty. The
3071 remainder of the field is one line per file, each line
3072 being indented by one space and containing a number of
3073 sub-fields separated by spaces.
3077 In the <file>.dsc</file> file, each line contains the MD5
3078 checksum, size and filename of the tar file and (if applicable)
3079 diff file which make up the remainder of the source
3081 That is, the parts which are not the <tt>.dsc</tt>.
3083 The exact forms of the filenames are described
3084 in <ref id="pkg-sourcearchives">.
3088 In the <file>.changes</file> file this contains one line per
3089 file being uploaded. Each line contains the MD5 checksum,
3090 size, section and priority and the filename.
3091 The <qref id="f-Section">section</qref>
3092 and <qref id="f-Priority">priority</qref>
3093 are the values of the corresponding fields in
3094 the main source control file. If no section or priority is
3095 specified then <tt>-</tt> should be used, though section
3096 and priority values must be specified for new packages to
3097 be installed properly.
3101 The special value <tt>byhand</tt> for the section in a
3102 <tt>.changes</tt> file indicates that the file in question
3103 is not an ordinary package file and must by installed by
3104 hand by the distribution maintainers. If the section is
3105 <tt>byhand</tt> the priority should be <tt>-</tt>.
3109 If a new Debian revision of a package is being shipped and
3110 no new original source archive is being distributed the
3111 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3112 entry for the original source archive
3113 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3114 but the <file>.changes</file> file should leave it out. In
3115 this case the original source archive on the distribution
3116 site must match exactly, byte-for-byte, the original
3117 source archive which was used to generate the
3118 <file>.dsc</file> file and diff which are being uploaded.</p>
3121 <sect1 id="f-Closes">
3122 <heading><tt>Closes</tt></heading>
3125 A space-separated list of bug report numbers that the upload
3126 governed by the .changes file closes.
3133 <heading>User-defined fields</heading>
3136 Additional user-defined fields may be added to the
3137 source package control file. Such fields will be
3138 ignored, and not copied to (for example) binary or
3139 source package control files or upload control files.
3143 If you wish to add additional unsupported fields to
3144 these output files you should use the mechanism
3149 Fields in the main source control information file with
3150 names starting <tt>X</tt>, followed by one or more of
3151 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3152 be copied to the output files. Only the part of the
3153 field name after the hyphen will be used in the output
3154 file. Where the letter <tt>B</tt> is used the field
3155 will appear in binary package control files, where the
3156 letter <tt>S</tt> is used in source package control
3157 files and where <tt>C</tt> is used in upload control
3158 (<tt>.changes</tt>) files.
3162 For example, if the main source information control file
3165 XBS-Comment: I stand between the candle and the star.
3167 then the binary and source package control files will contain the
3170 Comment: I stand between the candle and the star.
3179 <chapt id="maintainerscripts">
3180 <heading>Package maintainer scripts and installation procedure</heading>
3183 <heading>Introduction to package maintainer scripts</heading>
3186 It is possible to supply scripts as part of a package which
3187 the package management system will run for you when your
3188 package is installed, upgraded or removed.
3192 These scripts are the files <prgn>preinst</prgn>,
3193 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3194 control area of the package. They must be proper executable
3195 files; if they are scripts (which is recommended), they must
3196 start with the usual <tt>#!</tt> convention. They should be
3197 readable and executable by anyone, and not world-writable.
3201 The package management system looks at the exit status from
3202 these scripts. It is important that they exit with a
3203 non-zero status if there is an error, so that the package
3204 management system can stop its processing. For shell
3205 scripts this means that you <em>almost always</em> need to
3206 use <tt>set -e</tt> (this is usually true when writing shell
3207 scripts, in fact). It is also important, of course, that
3208 they don't exit with a non-zero status if everything went
3213 When a package is upgraded a combination of the scripts from
3214 the old and new packages is called during the upgrade
3215 procedure. If your scripts are going to be at all
3216 complicated you need to be aware of this, and may need to
3217 check the arguments to your scripts.
3221 Broadly speaking the <prgn>preinst</prgn> is called before
3222 (a particular version of) a package is installed, and the
3223 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3224 before (a version of) a package is removed and the
3225 <prgn>postrm</prgn> afterwards.
3229 Programs called from maintainer scripts should not normally
3230 have a path prepended to them. Before installation is
3231 started, the package management system checks to see if the
3232 programs <prgn>ldconfig</prgn>,
3233 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3234 and <prgn>update-rc.d</prgn> can be found via the
3235 <tt>PATH</tt> environment variable. Those programs, and any
3236 other program that one would expect to be on the
3237 <tt>PATH</tt>, should thus be invoked without an absolute
3238 pathname. Maintainer scripts should also not reset the
3239 <tt>PATH</tt>, though they might choose to modify it by
3240 prepending or appending package-specific directories. These
3241 considerations really apply to all shell scripts.</p>
3244 <sect id="idempotency">
3245 <heading>Maintainer scripts Idempotency</heading>
3248 It is necessary for the error recovery procedures that the
3249 scripts be idempotent. This means that if it is run
3250 successfully, and then it is called again, it doesn't bomb
3251 out or cause any harm, but just ensures that everything is
3252 the way it ought to be. If the first call failed, or
3253 aborted half way through for some reason, the second call
3254 should merely do the things that were left undone the first
3255 time, if any, and exit with a success status if everything
3257 This is so that if an error occurs, the user interrupts
3258 <prgn>dpkg</prgn> or some other unforeseen circumstance
3259 happens you don't leave the user with a badly-broken
3260 package when <prgn>dpkg</prgn> attempts to repeat the
3266 <sect id="controllingterminal">
3267 <heading>Controlling terminal for maintainer scripts</heading>
3270 The maintainer scripts are guaranteed to run with a
3271 controlling terminal and can interact with the user.
3272 If they need to prompt for passwords, do full-screen
3273 interaction or something similar you should do these
3274 things to and from <file>/dev/tty</file>, since
3275 <prgn>dpkg</prgn> will at some point redirect scripts'
3276 standard input and output so that it can log the
3277 installation process. Likewise, because these scripts
3278 may be executed with standard output redirected into a
3279 pipe for logging purposes, Perl scripts should set
3280 unbuffered output by setting <tt>$|=1</tt> so that the
3281 output is printed immediately rather than being
3286 Each script should return a zero exit status for
3287 success, or a nonzero one for failure.
3291 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3296 <list compact="compact">
3298 <var>new-preinst</var> <tt>install</tt>
3301 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3304 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3307 <var>old-preinst</var> <tt>abort-upgrade</tt>
3308 <var>new-version</var>
3313 <list compact="compact">
3315 <var>postinst</var> <tt>configure</tt>
3316 <var>most-recently-configured-version</var>
3319 <var>old-postinst</var> <tt>abort-upgrade</tt>
3320 <var>new-version</var>
3323 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3324 <tt>in-favour</tt> <var>package</var>
3325 <var>new-version</var>
3328 <var>deconfigured's-postinst</var>
3329 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3330 <var>failed-install-package</var> <var>version</var>
3331 <tt>removing</tt> <var>conflicting-package</var>
3337 <list compact="compact">
3339 <var>prerm</var> <tt>remove</tt>
3342 <var>old-prerm</var> <tt>upgrade</tt>
3343 <var>new-version</var>
3346 <var>new-prerm</var> <tt>failed-upgrade</tt>
3347 <var>old-version</var>
3350 <var>conflictor's-prerm</var> <tt>remove</tt>
3351 <tt>in-favour</tt> <var>package</var>
3352 <var>new-version</var>
3355 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3356 <tt>in-favour</tt> <var>package-being-installed</var>
3357 <var>version</var> <tt>removing</tt>
3358 <var>conflicting-package</var>
3364 <list compact="compact">
3366 <var>postrm</var> <tt>remove</tt>
3369 <var>postrm</var> <tt>purge</tt>
3372 <var>old-postrm</var> <tt>upgrade</tt>
3373 <var>new-version</var>
3376 <var>new-postrm</var> <tt>failed-upgrade</tt>
3377 <var>old-version</var>
3380 <var>new-postrm</var> <tt>abort-install</tt>
3383 <var>new-postrm</var> <tt>abort-install</tt>
3384 <var>old-version</var>
3387 <var>new-postrm</var> <tt>abort-upgrade</tt>
3388 <var>old-version</var>
3391 <var>disappearer's-postrm</var> <tt>disappear</tt>
3392 <var>overwriter</var>
3393 <var>overwriter-version</var>
3399 <sect id="unpackphase">
3400 <heading>Details of unpack phase of installation or upgrade</heading>
3403 The procedure on installation/upgrade/overwrite/disappear
3404 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3405 stage of <tt>dpkg --install</tt>) is as follows. In each
3406 case, if a major error occurs (unless listed below) the
3407 actions are, in general, run backwards - this means that the
3408 maintainer scripts are run with different arguments in
3409 reverse order. These are the "error unwind" calls listed
3416 If a version of the package is already installed, call
3417 <example compact="compact">
3418 <var>old-prerm</var> upgrade <var>new-version</var>
3422 If the script runs but exits with a non-zero
3423 exit status, <prgn>dpkg</prgn> will attempt:
3424 <example compact="compact">
3425 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3427 Error unwind, for both the above cases:
3428 <example compact="compact">
3429 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3436 If a "conflicting" package is being removed at the same time:
3439 If any packages depended on that conflicting
3440 package and <tt>--auto-deconfigure</tt> is
3441 specified, call, for each such package:
3442 <example compact="compact">
3443 <var>deconfigured's-prerm</var> deconfigure \
3444 in-favour <var>package-being-installed</var> <var>version</var> \
3445 removing <var>conflicting-package</var> <var>version</var>
3448 <example compact="compact">
3449 <var>deconfigured's-postinst</var> abort-deconfigure \
3450 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3451 removing <var>conflicting-package</var> <var>version</var>
3453 The deconfigured packages are marked as
3454 requiring configuration, so that if
3455 <tt>--install</tt> is used they will be
3456 configured again if possible.
3459 To prepare for removal of the conflicting package, call:
3460 <example compact="compact">
3461 <var>conflictor's-prerm</var> remove \
3462 in-favour <var>package</var> <var>new-version</var>
3465 <example compact="compact">
3466 <var>conflictor's-postinst</var> abort-remove \
3467 in-favour <var>package</var> <var>new-version</var>
3476 If the package is being upgraded, call:
3477 <example compact="compact">
3478 <var>new-preinst</var> upgrade <var>old-version</var>
3482 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3484 If that too fails, then
3486 <var>old-postinst</var> abort-upgrade <var>old-version</var>
3491 Otherwise, if the package had some configuration
3492 files from a previous version installed (i.e., it
3493 is in the "configuration files only" state):
3494 <example compact="compact">
3495 <var>new-preinst</var> install <var>old-version</var>
3499 <var>new-postrm</var> abort-install <var>old-version</var>
3503 Otherwise (i.e., the package was completely purged):
3504 <example compact="compact">
3505 <var>new-preinst</var> install
3508 <example compact="compact">
3509 <var>new-postrm</var> abort-install
3517 The new package's files are unpacked, overwriting any
3518 that may be on the system already, for example any
3519 from the old version of the same package or from
3520 another package. Backups of the old files are kept
3521 temporarily, and if anything goes wrong the package
3522 management system will attempt to put them back as
3523 part of the error unwind.
3527 It is an error for a package to contain files which
3528 are on the system in another package, unless
3529 <tt>Replaces</tt> is used (see <ref id="replaces">).
3531 The following paragraph is not currently the case:
3532 Currently the <tt>- - force-overwrite</tt> flag is
3533 enabled, downgrading it to a warning, but this may not
3539 It is a more serious error for a package to contain a
3540 plain file or other kind of non-directory where another
3541 package has a directory (again, unless
3542 <tt>Replaces</tt> is used). This error can be
3543 overridden if desired using
3544 <tt>--force-overwrite-dir</tt>, but this is not
3549 Packages which overwrite each other's files produce
3550 behavior which, though deterministic, is hard for the
3551 system administrator to understand. It can easily
3552 lead to "missing" programs if, for example, a package
3553 is installed which overwrites a file from another
3554 package, and is then removed again.<footnote>
3555 Part of the problem is due to what is arguably a
3556 bug in <prgn>dpkg</prgn>.
3561 A directory will never be replaced by a symbolic link
3562 to a directory or vice versa; instead, the existing
3563 state (symlink or not) will be left alone and
3564 <prgn>dpkg</prgn> will follow the symlink if there is
3573 If the package is being upgraded, call
3574 <example compact="compact">
3575 <var>old-postrm</var> upgrade <var>new-version</var>
3579 If this fails, <prgn>dpkg</prgn> will attempt:
3580 <example compact="compact">
3581 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3583 Error unwind, for both cases:
3584 <example compact="compact">
3585 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3592 This is the point of no return - if
3593 <prgn>dpkg</prgn> gets this far, it won't back off
3594 past this point if an error occurs. This will
3595 leave the package in a fairly bad state, which
3596 will require a successful re-installation to clear
3597 up, but it's when <prgn>dpkg</prgn> starts doing
3598 things that are irreversible.
3603 Any files which were in the old version of the package
3604 but not in the new are removed.
3608 The new file list replaces the old.
3612 The new maintainer scripts replace the old.
3616 Any packages all of whose files have been overwritten
3617 during the installation, and which aren't required for
3618 dependencies, are considered to have been removed.
3619 For each such package
3622 <prgn>dpkg</prgn> calls:
3623 <example compact="compact">
3624 <var>disappearer's-postrm</var> disappear \
3625 <var>overwriter</var> <var>overwriter-version</var>
3629 The package's maintainer scripts are removed.
3632 It is noted in the status database as being in a
3633 sane state, namely not installed (any conffiles
3634 it may have are ignored, rather than being
3635 removed by <prgn>dpkg</prgn>). Note that
3636 disappearing packages do not have their prerm
3637 called, because <prgn>dpkg</prgn> doesn't know
3638 in advance that the package is going to
3645 Any files in the package we're unpacking that are also
3646 listed in the file lists of other packages are removed
3647 from those lists. (This will lobotomize the file list
3648 of the "conflicting" package if there is one.)
3652 The backup files made during installation, above, are
3658 The new package's status is now sane, and recorded as
3663 Here is another point of no return - if the
3664 conflicting package's removal fails we do not unwind
3665 the rest of the installation; the conflicting package
3666 is left in a half-removed limbo.
3671 If there was a conflicting package we go and do the
3672 removal actions (described below), starting with the
3673 removal of the conflicting package's files (any that
3674 are also in the package being installed have already
3675 been removed from the conflicting package's file list,
3676 and so do not get removed now).
3682 <sect id="configdetails"><heading>Details of configuration</heading>
3685 When we configure a package (this happens with <tt>dpkg
3686 --install</tt> and <tt>dpkg --configure</tt>), we first
3687 update any <tt>conffile</tt>s and then call:
3688 <example compact="compact">
3689 <var>postinst</var> configure <var>most-recently-configured-version</var>
3694 No attempt is made to unwind after errors during
3699 If there is no most recently configured version
3700 <prgn>dpkg</prgn> will pass a null argument.
3703 Historical note: Truly ancient (pre-1997) versions of
3704 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3705 (including the angle brackets) in this case. Even older
3706 ones did not pass a second argument at all, under any
3707 circumstance. Note that upgrades using such an old dpkg
3708 version are unlikely to work for other reasons, even if
3709 this old argument behavior is handled by your postinst script.
3715 <sect id="removedetails"><heading>Details of removal and/or
3716 configuration purging</heading>
3721 <example compact="compact">
3722 <var>prerm</var> remove
3726 The package's files are removed (except <tt>conffile</tt>s).
3729 <example compact="compact">
3730 <var>postrm</var> remove
3735 All the maintainer scripts except the <prgn>postrm</prgn>
3740 If we aren't purging the package we stop here. Note
3741 that packages which have no <prgn>postrm</prgn> and no
3742 <tt>conffile</tt>s are automatically purged when
3743 removed, as there is no difference except for the
3744 <prgn>dpkg</prgn> status.
3748 The <tt>conffile</tt>s and any backup files
3749 (<tt>~</tt>-files, <tt>#*#</tt> files,
3750 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3754 <example compact="compact">
3755 <var>postrm</var> purge
3759 The package's file list is removed.
3763 If there are problems during this process, we call
3764 <example compact="compact">postinst
3765 abort-remove</example>. No other attempt is made to unwind
3766 after errors during removal.
3772 <chapt id="relationships">
3773 <heading>Declaring relationships between packages</heading>
3775 <sect id="depsyntax">
3776 <heading>Syntax of relationship fields</heading>
3779 These fields all have a uniform syntax. They are a list of
3780 package names separated by commas.
3784 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3785 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3786 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3787 control file fields of the package, which declare
3788 dependencies on other packages, the package names listed may
3789 also include lists of alternative package names, separated
3790 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3791 if any one of the alternative packages is installed, that
3792 part of the dependency is considered to be satisfied.
3796 All of the fields except for <tt>Provides</tt> may restrict
3797 their applicability to particular versions of each named
3798 package. This is done in parentheses after each individual
3799 package name; the parentheses should contain a relation from
3800 the list below followed by a version number, in the format
3801 described in <ref id="f-Version">.
3805 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3806 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3807 strictly earlier, earlier or equal, exactly equal, later or
3808 equal and strictly later, respectively. The deprecated
3809 forms <tt><</tt> and <tt>></tt> were used to mean
3810 earlier/later or equal, rather than strictly earlier/later,
3811 so they should not appear in new packages (though
3812 <prgn>dpkg</prgn> still supports them).
3816 Whitespace may appear at any point in the version
3817 specification subject to the rules in <ref
3818 id="controlsyntax">, and must appear where it's necessary to
3819 disambiguate; it is not otherwise significant. For
3820 consistency and in case of future changes to
3821 <prgn>dpkg</prgn> it is recommended that a single space be
3822 used after a version relationship and before a version
3823 number; it is also conventional to put a single space after
3824 each comma, on either side of each vertical bar, and before
3825 each open parenthesis.
3829 For example, a list of dependencies might appear as:
3830 <example compact="compact">
3833 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3838 All fields that specify build-time relationships
3839 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3840 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3841 may be restricted to a certain set of architectures. This
3842 is indicated in brackets after each individual package name and
3843 the optional version specification. The brackets enclose a
3844 list of Debian architecture names separated by whitespace.
3845 Exclamation marks may be prepended to each of the names.
3846 (It is not permitted for some names to be prepended with
3847 exclamation marks and others not.) If the current Debian
3848 host architecture is not in this list and there are no
3849 exclamation marks in the list, or it is in the list with a
3850 prepended exclamation mark, the package name and the
3851 associated version specification are ignored completely for
3852 the purposes of defining the relationships.
3857 <example compact="compact">
3859 Build-Depends-Indep: texinfo
3860 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3861 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3866 Note that the binary package relationship fields such as
3867 <tt>Depends</tt> appear in one of the binary package
3868 sections of the control file, whereas the build-time
3869 relationships such as <tt>Build-Depends</tt> appear in the
3870 source package section of the control file (which is the
3875 <sect id="binarydeps">
3876 <heading>Binary Dependencies - <tt>Depends</tt>,
3877 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3878 <tt>Pre-Depends</tt>
3882 Packages can declare in their control file that they have
3883 certain relationships to other packages - for example, that
3884 they may not be installed at the same time as certain other
3885 packages, and/or that they depend on the presence of others.
3889 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3890 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3891 <tt>Conflicts</tt> control file fields.
3895 These six fields are used to declare a dependency
3896 relationship by one package on another. Except for
3897 <tt>Enhances</tt>, they appear in the depending (binary)
3898 package's control file. (<tt>Enhances</tt> appears in the
3899 recommending package's control file.)
3903 A <tt>Depends</tt> field takes effect <em>only</em> when a
3904 package is to be configured. It does not prevent a package
3905 being on the system in an unconfigured state while its
3906 dependencies are unsatisfied, and it is possible to replace
3907 a package whose dependencies are satisfied and which is
3908 properly installed with a different version whose
3909 dependencies are not and cannot be satisfied; when this is
3910 done the depending package will be left unconfigured (since
3911 attempts to configure it will give errors) and will not
3912 function properly. If it is necessary, a
3913 <tt>Pre-Depends</tt> field can be used, which has a partial
3914 effect even when a package is being unpacked, as explained
3915 in detail below. (The other three dependency fields,
3916 <tt>Recommends</tt>, <tt>Suggests</tt> and
3917 <tt>Enhances</tt>, are only used by the various front-ends
3918 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3922 For this reason packages in an installation run are usually
3923 all unpacked first and all configured later; this gives
3924 later versions of packages with dependencies on later
3925 versions of other packages the opportunity to have their
3926 dependencies satisfied.
3930 The <tt>Depends</tt> field thus allows package maintainers
3931 to impose an order in which packages should be configured.
3935 The meaning of the five dependency fields is as follows:
3937 <tag><tt>Depends</tt></tag>
3940 This declares an absolute dependency. A package will
3941 not be configured unless all of the packages listed in
3942 its <tt>Depends</tt> field have been correctly
3947 The <tt>Depends</tt> field should be used if the
3948 depended-on package is required for the depending
3949 package to provide a significant amount of
3954 The <tt>Depends</tt> field should also be used if the
3955 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3956 <prgn>postrm</prgn> scripts require the package to be
3957 present in order to run. Note, however, that the
3958 <prgn>postrm</prgn> cannot rely on any non-essential
3959 packages to be present during the <tt>purge</tt>
3963 <tag><tt>Recommends</tt></tag>
3966 This declares a strong, but not absolute, dependency.
3970 The <tt>Recommends</tt> field should list packages
3971 that would be found together with this one in all but
3972 unusual installations.
3976 <tag><tt>Suggests</tt></tag>
3978 This is used to declare that one package may be more
3979 useful with one or more others. Using this field
3980 tells the packaging system and the user that the
3981 listed packages are related to this one and can
3982 perhaps enhance its usefulness, but that installing
3983 this one without them is perfectly reasonable.
3986 <tag><tt>Enhances</tt></tag>
3988 This field is similar to Suggests but works in the
3989 opposite direction. It is used to declare that a
3990 package can enhance the functionality of another
3994 <tag><tt>Pre-Depends</tt></tag>
3997 This field is like <tt>Depends</tt>, except that it
3998 also forces <prgn>dpkg</prgn> to complete installation
3999 of the packages named before even starting the
4000 installation of the package which declares the
4001 pre-dependency, as follows:
4005 When a package declaring a pre-dependency is about to
4006 be <em>unpacked</em> the pre-dependency can be
4007 satisfied if the depended-on package is either fully
4008 configured, <em>or even if</em> the depended-on
4009 package(s) are only unpacked or half-configured,
4010 provided that they have been configured correctly at
4011 some point in the past (and not removed or partially
4012 removed since). In this case, both the
4013 previously-configured and currently unpacked or
4014 half-configured versions must satisfy any version
4015 clause in the <tt>Pre-Depends</tt> field.
4019 When the package declaring a pre-dependency is about
4020 to be <em>configured</em>, the pre-dependency will be
4021 treated as a normal <tt>Depends</tt>, that is, it will
4022 be considered satisfied only if the depended-on
4023 package has been correctly configured.
4027 <tt>Pre-Depends</tt> should be used sparingly,
4028 preferably only by packages whose premature upgrade or
4029 installation would hamper the ability of the system to
4030 continue with any upgrade that might be in progress.
4034 <tt>Pre-Depends</tt> are also required if the
4035 <prgn>preinst</prgn> script depends on the named
4036 package. It is best to avoid this situation if
4044 When selecting which level of dependency to use you should
4045 consider how important the depended-on package is to the
4046 functionality of the one declaring the dependency. Some
4047 packages are composed of components of varying degrees of
4048 importance. Such a package should list using
4049 <tt>Depends</tt> the package(s) which are required by the
4050 more important components. The other components'
4051 requirements may be mentioned as Suggestions or
4052 Recommendations, as appropriate to the components' relative
4057 <sect id="conflicts">
4058 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4061 When one binary package declares a conflict with another
4062 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4063 refuse to allow them to be installed on the system at the
4068 If one package is to be installed, the other must be removed
4069 first - if the package being installed is marked as
4070 replacing (see <ref id="replaces">) the one on the system,
4071 or the one on the system is marked as deselected, or both
4072 packages are marked <tt>Essential</tt>, then
4073 <prgn>dpkg</prgn> will automatically remove the package
4074 which is causing the conflict, otherwise it will halt the
4075 installation of the new package with an error. This
4076 mechanism is specifically designed to produce an error when
4077 the installed package is <tt>Essential</tt>, but the new
4082 A package will not cause a conflict merely because its
4083 configuration files are still installed; it must be at least
4088 A special exception is made for packages which declare a
4089 conflict with their own package name, or with a virtual
4090 package which they provide (see below): this does not
4091 prevent their installation, and allows a package to conflict
4092 with others providing a replacement for it. You use this
4093 feature when you want the package in question to be the only
4094 package providing some feature.
4098 A <tt>Conflicts</tt> entry should almost never have an
4099 "earlier than" version clause. This would prevent
4100 <prgn>dpkg</prgn> from upgrading or installing the package
4101 which declared such a conflict until the upgrade or removal
4102 of the conflicted-with package had been completed.
4106 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4110 As well as the names of actual ("concrete") packages, the
4111 package relationship fields <tt>Depends</tt>,
4112 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4113 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4114 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4115 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4116 may mention "virtual packages".
4120 A <em>virtual package</em> is one which appears in the
4121 <tt>Provides</tt> control file field of another package.
4122 The effect is as if the package(s) which provide a
4123 particular virtual package name had been listed by name
4124 everywhere the virtual package name appears. (See also <ref
4129 If there are both concrete and virtual packages of the same
4130 name, then the dependency may be satisfied (or the conflict
4131 caused) by either the concrete package with the name in
4132 question or any other concrete package which provides the
4133 virtual package with the name in question. This is so that,
4134 for example, supposing we have
4135 <example compact="compact">
4139 and someone else releases an enhanced version of the
4140 <tt>bar</tt> package (for example, a non-US variant), they
4142 <example compact="compact">
4146 and the <tt>bar-plus</tt> package will now also satisfy the
4147 dependency for the <tt>foo</tt> package.
4151 If a dependency or a conflict has a version number attached
4152 then only real packages will be considered to see whether
4153 the relationship is satisfied (or the prohibition violated,
4154 for a conflict) - it is assumed that a real package which
4155 provides the virtual package is not of the "right" version.
4156 So, a <tt>Provides</tt> field may not contain version
4157 numbers, and the version number of the concrete package
4158 which provides a particular virtual package will not be
4159 looked at when considering a dependency on or conflict with
4160 the virtual package name.
4164 It is likely that the ability will be added in a future
4165 release of <prgn>dpkg</prgn> to specify a version number for
4166 each virtual package it provides. This feature is not yet
4167 present, however, and is expected to be used only
4172 If you want to specify which of a set of real packages
4173 should be the default to satisfy a particular dependency on
4174 a virtual package, you should list the real package as an
4175 alternative before the virtual one.
4180 <sect id="replaces"><heading>Overwriting files and replacing
4181 packages - <tt>Replaces</tt></heading>
4184 Packages can declare in their control file that they should
4185 overwrite files in certain other packages, or completely
4186 replace other packages. The <tt>Replaces</tt> control file
4187 field has these two distinct purposes.
4190 <sect1><heading>Overwriting files in other packages</heading>
4193 Firstly, as mentioned before, it is usually an error for a
4194 package to contain files which are on the system in
4199 However, if the overwriting package declares that it
4200 <tt>Replaces</tt> the one containing the file being
4201 overwritten, then <prgn>dpkg</prgn> will replace the file
4202 from the old package with that from the new. The file
4203 will no longer be listed as "owned" by the old package.
4207 If a package is completely replaced in this way, so that
4208 <prgn>dpkg</prgn> does not know of any files it still
4209 contains, it is considered to have "disappeared". It will
4210 be marked as not wanted on the system (selected for
4211 removal) and not installed. Any <tt>conffile</tt>s
4212 details noted for the package will be ignored, as they
4213 will have been taken over by the overwriting package. The
4214 package's <prgn>postrm</prgn> script will be run with a
4215 special argument to allow the package to do any final
4216 cleanup required. See <ref id="mscriptsinstact">.
4219 Replaces is a one way relationship -- you have to
4220 install the replacing package after the replaced
4227 For this usage of <tt>Replaces</tt>, virtual packages (see
4228 <ref id="virtual">) are not considered when looking at a
4229 <tt>Replaces</tt> field - the packages declared as being
4230 replaced must be mentioned by their real names.
4234 Furthermore, this usage of <tt>Replaces</tt> only takes
4235 effect when both packages are at least partially on the
4236 system at once, so that it can only happen if they do not
4237 conflict or if the conflict has been overridden.
4242 <sect1><heading>Replacing whole packages, forcing their
4246 Secondly, <tt>Replaces</tt> allows the packaging system to
4247 resolve which package should be removed when there is a
4248 conflict - see <ref id="conflicts">. This usage only
4249 takes effect when the two packages <em>do</em> conflict,
4250 so that the two usages of this field do not interfere with
4255 In this situation, the package declared as being replaced
4256 can be a virtual package, so for example, all mail
4257 transport agents (MTAs) would have the following fields in
4258 their control files:
4259 <example compact="compact">
4260 Provides: mail-transport-agent
4261 Conflicts: mail-transport-agent
4262 Replaces: mail-transport-agent
4264 ensuring that only one MTA can be installed at any one
4269 <sect id="sourcebinarydeps">
4270 <heading>Relationships between source and binary packages -
4271 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4272 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4276 Source packages that require certain binary packages to be
4277 installed or absent at the time of building the package
4278 can declare relationships to those binary packages.
4282 This is done using the <tt>Build-Depends</tt>,
4283 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4284 <tt>Build-Conflicts-Indep</tt> control file fields.
4288 Build-dependencies on "build-essential" binary packages can be
4289 omitted. Please see <ref id="pkg-relations"> for more information.
4293 The dependencies and conflicts they define must be satisfied
4294 (as defined earlier for binary packages) in order to invoke
4295 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4297 If you make "build-arch" or "binary-arch", you need
4298 Build-Depends. If you make "build-indep" or
4299 "binary-indep", you need Build-Depends and
4300 Build-Depends-Indep. If you make "build" or "binary",
4304 There is no Build-Depends-Arch; the autobuilders will
4305 only need the Build-Depends if they know how to build
4306 only build-arch and binary-arch. Anyone building the
4307 build-indep/binary-indep targets is basically assumed to
4308 be building the whole package and so installs all build
4312 The purpose of the original split, I recall, was so that
4313 the autobuilders wouldn't need to install extra packages
4314 needed only for the binary-indep targets. But without a
4315 build-arch/build-indep split, this didn't work, since
4316 most of the work is done in the build target, not in the
4322 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4324 The <tt>Build-Depends</tt> and
4325 <tt>Build-Conflicts</tt> fields must be satisfied when
4326 any of the following targets is invoked:
4327 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4328 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4329 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4331 <tag><tt>Build-Depends-Indep</tt>,
4332 <tt>Build-Conflicts-Indep</tt></tag>
4334 The <tt>Build-Depends-Indep</tt> and
4335 <tt>Build-Conflicts-Indep</tt> fields must be
4336 satisfied when any of the following targets is
4337 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4338 <tt>binary</tt> and <tt>binary-indep</tt>.
4348 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4351 Packages containing shared libraries must be constructed with
4352 a little care to make sure that the shared library is always
4353 available. This is especially important for packages whose
4354 shared libraries are vitally important, such as the C library
4355 (currently <tt>libc6</tt>).
4359 Packages involving shared libraries should be split up into
4360 several binary packages. This section mostly deals with how
4361 this separation is to be accomplished; rules for files within
4362 the shared library packages are in <ref id="libraries"> instead.
4365 <sect id="sharedlibs-runtime">
4366 <heading>Run-time shared libraries</heading>
4369 The run-time shared library needs to be placed in a package
4370 whose name changes whenever the shared object version
4373 Since it is common place to install several versions of a
4374 package that just provides shared libraries, it is a
4375 good idea that that the library package should not
4376 contain any extraneous non-versioned files, unless they
4377 happen to be in versioned directories.</p>
4379 The most common mechanism is to place it in a package
4381 <package><var>libraryname</var><var>soversion</var></package>,
4382 where <file><var>soversion</var></file> is the version number
4383 in the soname of the shared library<footnote>
4384 The soname is the shared object name: it's the thing
4385 that has to match exactly between building an executable
4386 and running it for the dynamic linker to be able run the
4387 program. For example, if the soname of the library is
4388 <file>libfoo.so.6</file>, the library package would be
4389 called <file>libfoo6</file>.
4391 Alternatively, if it would be confusing to directly append
4392 <var>soversion</var> to <var>libraryname</var> (e.g. because
4393 <var>libraryname</var> itself ends in a number), you may use
4394 <package><var>libraryname</var>-<var>soversion</var></package> and
4395 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4400 If your package includes run-time support programs that
4401 do not need to be invoked manually by users, but are
4402 nevertheless required for the package to function, then it
4403 is recommended that these programs are placed
4404 (if they are binary) in a subdirectory of
4405 <file>/usr/lib</file>, preferably under
4406 <file>/usr/lib/</file><var>package-name</var>.
4407 If the program is architecture independent, the
4408 recommendation is for it to be placed in a subdirectory of
4409 <file>/usr/share</file> instead, preferably under
4410 <file>/usr/share/</file><var>package-name</var>.
4415 If you have several shared libraries built from the same
4416 source tree you may lump them all together into a single
4417 shared library package, provided that you change all of
4418 their sonames at once (so that you don't get filename
4419 clashes if you try to install different versions of the
4420 combined shared libraries package).
4424 The package should install the shared libraries under
4425 their normal names. For example, the <package>libgdbm3</package>
4426 package should install <file>libgdbm.so.3.0.0</file> as
4427 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4428 renamed or re-linked by any <prgn>prerm</prgn> or
4429 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4430 of renaming things safely without affecting running programs,
4431 and attempts to interfere with this are likely to lead to
4436 Shared libraries should not be installed executable, since
4437 the dynamic linker does not require this and trying to
4438 execute a shared library usually results in a core dump.
4442 The run-time library package should include the symbolic link that
4443 <prgn>ldconfig</prgn> would create for the shared libraries.
4444 For example, the <package>libgdbm3</package> package should include
4445 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4446 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4447 linker (for example <prgn>ld.so</prgn> or
4448 <prgn>ld-linux.so.*</prgn>) can find the library between the
4449 time that <prgn>dpkg</prgn> installs it and the time that
4450 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4452 The package management system requires the library to be
4453 placed before the symbolic link pointing to it in the
4454 <file>.deb</file> file. This is so that when
4455 <prgn>dpkg</prgn> comes to install the symlink
4456 (overwriting the previous symlink pointing at an older
4457 version of the library), the new shared library is already
4458 in place. In the past, this was achieved by creating the
4459 library in the temporary packaging directory before
4460 creating the symlink. Unfortunately, this was not always
4461 effective, since the building of the tar file in the
4462 <file>.deb</file> depended on the behavior of the underlying
4463 file system. Some file systems (such as reiserfs) reorder
4464 the files so that the order of creation is forgotten.
4465 Since version 1.7.0, <prgn>dpkg</prgn>
4466 reorders the files itself as necessary when building a
4467 package. Thus it is no longer important to concern
4468 oneself with the order of file creation.
4472 <sect1 id="ldconfig">
4473 <heading><tt>ldconfig</tt></heading>
4476 Any package installing shared libraries in one of the default
4477 library directories of the dynamic linker (which are currently
4478 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4479 listed in <file>/etc/ld.so.conf</file><footnote>
4481 <list compact="compact">
4482 <item>/usr/X11R6/lib/Xaw3d</item>
4483 <item>/usr/local/lib</item>
4484 <item>/usr/lib/libc5-compat</item>
4485 <item>/lib/libc5-compat</item>
4486 <item>/usr/X11R6/lib</item>
4489 must use <prgn>ldconfig</prgn> to update the shared library
4494 The package must call <prgn>ldconfig</prgn> in the
4495 <prgn>postinst</prgn> script if the first argument is
4496 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4497 optionally invoke <prgn>ldconfig</prgn> at other times. The
4498 package should call <prgn>ldconfig</prgn> in the
4499 <prgn>postrm</prgn> script if the first argument is
4500 <tt>remove</tt>. The maintainer scripts must not invoke
4501 <prgn>ldconfig</prgn> under any circumstances other than those
4502 described in this paragraph.<footnote>
4504 During install or upgrade, the preinst is called before
4505 the new files are installed, so calling "ldconfig" is
4506 pointless. The preinst of an existing package can also be
4507 called if an upgrade fails. However, this happens during
4508 the critical time when a shared libs may exist on-disk
4509 under a temporary name. Thus, it is dangerous and
4510 forbidden by current policy to call "ldconfig" at this
4515 When a package is installed or upgraded, "postinst
4516 configure" runs after the new files are safely on-disk.
4517 Since it is perfectly safe to invoke ldconfig
4518 unconditionally in a postinst, it is OK for a package to
4519 simply put ldconfig in its postinst without checking the
4520 argument. The postinst can also be called to recover from
4521 a failed upgrade. This happens before any new files are
4522 unpacked, so there is no reason to call "ldconfig" at this
4527 For a package that is being removed, prerm is
4528 called with all the files intact, so calling ldconfig is
4529 useless. The other calls to "prerm" happen in the case of
4530 upgrade at a time when all the files of the old package
4531 are on-disk, so again calling "ldconfig" is pointless.
4535 postrm, on the other hand, is called with the "remove"
4536 argument just after the files are removed, so this is the
4537 proper time to call "ldconfig" to notify the system of the
4538 fact shared libraries from the package are removed.
4539 The postrm can be called at several other times. At the
4540 time of "postrm purge", "postrm abort-install", or "postrm
4541 abort-upgrade", calling "ldconfig" is useless because the
4542 shared lib files are not on-disk. However, when "postrm"
4543 is invoked with arguments "upgrade", "failed-upgrade", or
4544 "disappear", a shared lib may exist on-disk under a
4553 <sect id="sharedlibs-runtime-progs">
4554 <heading>Run-time support programs</heading>
4557 If your package has some run-time support programs which use
4558 the shared library you must not put them in the shared
4559 library package. If you do that then you won't be able to
4560 install several versions of the shared library without
4561 getting filename clashes.
4565 Instead, either create another package for the runtime binaries
4566 (this package might typically be named
4567 <package><var>libraryname</var>-runtime</package>; note the absence
4568 of the <var>soversion</var> in the package name), or if the
4569 development package is small, include them in there.
4573 <sect id="sharedlibs-static">
4574 <heading>Static libraries</heading>
4577 The static library (<file><var>libraryname.a</var></file>)
4578 is usually provided in addition to the shared version.
4579 It is placed into the development package (see below).
4583 In some cases, it is acceptable for a library to be
4584 available in static form only; these cases include:
4586 <item>libraries for languages whose shared library support
4587 is immature or unstable</item>
4588 <item>libraries whose interfaces are in flux or under
4589 development (commonly the case when the library's
4590 major version number is zero, or where the ABI breaks
4591 across patchlevels)</item>
4592 <item>libraries which are explicitly intended to be
4593 available only in static form by their upstream
4598 <sect id="sharedlibs-dev">
4599 <heading>Development files</heading>
4602 The development files associated to a shared library need to be
4603 placed in a package called
4604 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4605 or if you prefer only to support one development version at a
4606 time, <package><var>libraryname</var>-dev</package>.
4610 In case several development versions of a library exist, you may
4611 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4612 <ref id="conflicts">) to ensure that the user only installs one
4613 development version at a time (as different development versions are
4614 likely to have the same header files in them, which would cause a
4615 filename clash if both were installed).
4619 The development package should contain a symlink for the associated
4620 shared library without a version number. For example, the
4621 <package>libgdbm-dev</package> package should include a symlink
4622 from <file>/usr/lib/libgdbm.so</file> to
4623 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4624 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4625 <file>libgdbm.so</file> when compiling dynamically.
4629 <sect id="sharedlibs-intradeps">
4630 <heading>Dependencies between the packages of the same library</heading>
4633 Typically the development version should have an exact
4634 version dependency on the runtime library, to make sure that
4635 compilation and linking happens correctly. The
4636 <tt>${Source-Version}</tt> substitution variable can be
4637 useful for this purpose.
4641 <sect id="sharedlibs-shlibdeps">
4642 <heading>Dependencies between the library and other packages -
4643 the <tt>shlibs</tt> system</heading>
4646 If a package contains a binary or library which links to a
4647 shared library, we must ensure that when the package is
4648 installed on the system, all of the libraries needed are
4649 also installed. This requirement led to the creation of the
4650 <tt>shlibs</tt> system, which is very simple in its design:
4651 any package which <em>provides</em> a shared library also
4652 provides information on the package dependencies required to
4653 ensure the presence of this library, and any package which
4654 <em>uses</em> a shared library uses this information to
4655 determine the dependencies it requires. The files which
4656 contain the mapping from shared libraries to the necessary
4657 dependency information are called <file>shlibs</file> files.
4661 Thus, when a package is built which contains any shared
4662 libraries, it must provide a <file>shlibs</file> file for other
4663 packages to use, and when a package is built which contains
4664 any shared libraries or compiled binaries, it must run
4665 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4666 on these to determine the libraries used and hence the
4667 dependencies needed by this package.<footnote>
4669 In the past, the shared libraries linked to were
4670 determined by calling <prgn>ldd</prgn>, but now
4671 <prgn>objdump</prgn> is used to do this. The only
4672 change this makes to package building is that
4673 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4674 libraries, whereas in the past this was unnecessary.
4675 The rest of this footnote explains the advantage that
4680 We say that a binary <tt>foo</tt> <em>directly</em> uses
4681 a library <tt>libbar</tt> if it is explicitly linked
4682 with that library (that is, it uses the flag
4683 <tt>-lbar</tt> during the linking stage). Other
4684 libraries that are needed by <tt>libbar</tt> are linked
4685 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4686 linker will load them automatically when it loads
4687 <tt>libbar</tt>. A package should depend on
4688 the libraries it directly uses, and the dependencies for
4689 those libraries should automatically pull in the other
4694 Unfortunately, the <prgn>ldd</prgn> program shows both
4695 the directly and indirectly used libraries, meaning that
4696 the dependencies determined included both direct and
4697 indirect dependencies. The use of <prgn>objdump</prgn>
4698 avoids this problem by determining only the directly
4703 A good example of where this helps is the following. We
4704 could update <tt>libimlib</tt> with a new version that
4705 supports a new graphics format called dgf (but retaining
4706 the same major version number). If we used the old
4707 <prgn>ldd</prgn> method, every package that uses
4708 <tt>libimlib</tt> would need to be recompiled so it
4709 would also depend on <tt>libdgf</tt> or it wouldn't run
4710 due to missing symbols. However with the new system,
4711 packages using <tt>libimlib</tt> can rely on
4712 <tt>libimlib</tt> itself having the dependency on
4713 <tt>libdgf</tt> and so they would not need rebuilding.
4719 In the following sections, we will first describe where the
4720 various <tt>shlibs</tt> files are to be found, then how to
4721 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4722 file format and how to create them if your package contains a
4727 <heading>The <tt>shlibs</tt> files present on the system</heading>
4730 There are several places where <tt>shlibs</tt> files are
4731 found. The following list gives them in the order in which
4733 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4734 (The first one which gives the required information is used.)
4740 <p><file>debian/shlibs.local</file></p>
4743 This lists overrides for this package. Its use is
4744 described below (see <ref id="shlibslocal">).
4749 <p><file>/etc/dpkg/shlibs.override</file></p>
4752 This lists global overrides. This list is normally
4753 empty. It is maintained by the local system
4759 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4762 When packages are being built, any
4763 <file>debian/shlibs</file> files are copied into the
4764 control file area of the temporary build directory and
4765 given the name <file>shlibs</file>. These files give
4766 details of any shared libraries included in the
4768 An example may help here. Let us say that the
4769 source package <tt>foo</tt> generates two binary
4770 packages, <tt>libfoo2</tt> and
4771 <tt>foo-runtime</tt>. When building the binary
4772 packages, the two packages are created in the
4773 directories <file>debian/libfoo2</file> and
4774 <file>debian/foo-runtime</file> respectively.
4775 (<file>debian/tmp</file> could be used instead of one
4776 of these.) Since <tt>libfoo2</tt> provides the
4777 <tt>libfoo</tt> shared library, it will require a
4778 <tt>shlibs</tt> file, which will be installed in
4779 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4781 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4782 when <prgn>dpkg-shlibdeps</prgn> is run on the
4784 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4786 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4787 determine whether <tt>foo-prog</tt>'s library
4788 dependencies are satisfied by any of the libraries
4789 provided by <tt>libfoo2</tt>. For this reason,
4790 <prgn>dpkg-shlibdeps</prgn> must only be run once
4791 all of the individual binary packages'
4792 <tt>shlibs</tt> files have been installed into the
4799 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4802 These are the <file>shlibs</file> files corresponding to
4803 all of the packages installed on the system, and are
4804 maintained by the relevant package maintainers.
4809 <p><file>/etc/dpkg/shlibs.default</file></p>
4812 This file lists any shared libraries whose packages
4813 have failed to provide correct <file>shlibs</file> files.
4814 It was used when the <file>shlibs</file> setup was first
4815 introduced, but it is now normally empty. It is
4816 maintained by the <tt>dpkg</tt> maintainer.
4824 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4825 <file>shlibs</file> files</heading>
4829 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4830 into your <file>debian/rules</file> file. If your package
4831 contains only compiled binaries and libraries (but no scripts),
4832 you can use a command such as:
4833 <example compact="compact">
4834 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4835 debian/tmp/usr/lib/*
4837 Otherwise, you will need to explicitly list the compiled
4838 binaries and libraries.<footnote>
4839 If you are using <tt>debhelper</tt>, the
4840 <prgn>dh_shlibdeps</prgn> program will do this work for
4841 you. It will also correctly handle multi-binary
4847 This command puts the dependency information into the
4848 <file>debian/substvars</file> file, which is then used by
4849 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4850 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4851 field in the control file for this to work.
4855 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4856 done. If it does complain you might need to create your own
4857 <file>debian/shlibs.local</file> file, as explained below (see
4858 <ref id="shlibslocal">).
4862 If you have multiple binary packages, you will need to call
4863 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4864 compiled libraries or binaries. In such a case, you will
4865 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4866 utilities to specify a different <file>substvars</file> file.
4870 For more details on dpkg-shlibdeps, please see
4871 <ref id="pkg-dpkg-shlibdeps"> and
4872 <manref name="dpkg-shlibdeps" section="1">.
4877 <heading>The <file>shlibs</file> File Format</heading>
4880 Each <file>shlibs</file> file has the same format. Lines
4881 beginning with <tt>#</tt> are considered to be comments and
4882 are ignored. Each line is of the form:
4883 <example compact="compact">
4884 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4889 We will explain this by reference to the example of the
4890 <tt>zlib1g</tt> package, which (at the time of writing)
4891 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4895 <var>library-name</var> is the name of the shared library,
4896 in this case <tt>libz</tt>. (This must match the name part
4897 of the soname, see below.)
4901 <var>soname-version-number</var> is the version part of the
4902 soname of the library. The soname is the thing that must
4903 exactly match for the library to be recognized by the
4904 dynamic linker, and is usually of the form
4905 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4906 example, <tt>libz.so.1</tt>.<footnote>
4907 This can be determined using the command
4908 <example compact="compact">
4909 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4912 The version part is the part which comes after
4913 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4917 <var>dependencies</var> has the same syntax as a dependency
4918 field in a binary package control file. It should give
4919 details of which packages are required to satisfy a binary
4920 built against the version of the library contained in the
4921 package. See <ref id="depsyntax"> for details.
4925 In our example, if the first version of the <tt>zlib1g</tt>
4926 package which contained a minor number of at least
4927 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4928 <tt>shlibs</tt> entry for this library could say:
4929 <example compact="compact">
4930 libz 1 zlib1g (>= 1:1.1.3)
4932 The version-specific dependency is to avoid warnings from
4933 the dynamic linker about using older shared libraries with
4939 <heading>Providing a <file>shlibs</file> file</heading>
4942 If your package provides a shared library, you should create
4943 a <file>shlibs</file> file following the format described above.
4944 It is usual to call this file <file>debian/shlibs</file> (but if
4945 you have multiple binary packages, you might want to call it
4946 <file>debian/shlibs.<var>package</var></file> instead). Then
4947 let <file>debian/rules</file> install it in the control area:
4948 <example compact="compact">
4949 install -m644 debian/shlibs debian/tmp/DEBIAN
4951 or, in the case of a multi-binary package:
4952 <example compact="compact">
4953 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4955 An alternative way of doing this is to create the
4956 <file>shlibs</file> file in the control area directly from
4957 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4958 file at all,<footnote>
4959 This is what <prgn>dh_makeshlibs</prgn> in the
4960 <tt>debhelper</tt> suite does.
4962 since the <file>debian/shlibs</file> file itself is ignored by
4963 <prgn>dpkg-shlibdeps</prgn>.
4967 As <prgn>dpkg-shlibdeps</prgn> reads the
4968 <file>DEBIAN/shlibs</file> files in all of the binary packages
4969 being built from this source package, all of the
4970 <file>DEBIAN/shlibs</file> files should be installed before
4971 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4976 <sect1 id="shlibslocal">
4977 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4980 This file is intended only as a <em>temporary</em> fix if
4981 your binaries or libraries depend on a library whose package
4982 does not yet provide a correct <file>shlibs</file> file.
4986 We will assume that you are trying to package a binary
4987 <tt>foo</tt>. When you try running
4988 <prgn>dpkg-shlibdeps</prgn> you get the following error
4989 message (<tt>-O</tt> displays the dependency information on
4990 <tt>stdout</tt> instead of writing it to
4991 <tt>debian/substvars</tt>, and the lines have been wrapped
4992 for ease of reading):
4993 <example compact="compact">
4994 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4995 dpkg-shlibdeps: warning: unable to find dependency
4996 information for shared library libbar (soname 1,
4997 path /usr/lib/libbar.so.1, dependency field Depends)
4998 shlibs:Depends=libc6 (>= 2.2.2-2)
5000 You can then run <prgn>ldd</prgn> on the binary to find the
5001 full location of the library concerned:
5002 <example compact="compact">
5004 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5005 libc.so.6 => /lib/libc.so.6 (0x40032000)
5006 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5008 So the <prgn>foo</prgn> binary depends on the
5009 <prgn>libbar</prgn> shared library, but no package seems to
5010 provide a <file>*.shlibs</file> file handling
5011 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5012 determine the package responsible:
5013 <example compact="compact">
5014 $ dpkg -S /usr/lib/libbar.so.1
5015 bar1: /usr/lib/libbar.so.1
5016 $ dpkg -s bar1 | grep Version
5019 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5020 is the one we are using. Now we can file a bug against the
5021 <tt>bar1</tt> package and create our own
5022 <file>debian/shlibs.local</file> to locally fix the problem.
5023 Including the following line into your
5024 <file>debian/shlibs.local</file> file:
5025 <example compact="compact">
5026 libbar 1 bar1 (>= 1.0-1)
5028 should allow the package build to work.
5032 As soon as the maintainer of <tt>bar1</tt> provides a
5033 correct <file>shlibs</file> file, you should remove this line
5034 from your <file>debian/shlibs.local</file> file. (You should
5035 probably also then have a versioned <tt>Build-Depends</tt>
5036 on <tt>bar1</tt> to help ensure that others do not have the
5037 same problem building your package.)
5046 <chapt id="opersys"><heading>The Operating System</heading>
5049 <heading>Filesystem hierarchy</heading>
5053 <heading>Filesystem Structure</heading>
5056 The location of all installed files and directories must
5057 comply with the Filesystem Hierarchy Standard (FHS),
5058 version 2.1, except where doing so would violate other
5059 terms of Debian Policy. The version of this document
5060 referred here can be found in the <tt>debian-policy</tt>
5062 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5063 name="FHS (Debian copy)"> alongside this manual (or, if
5064 you have the <package>debian-policy</package> installed,
5066 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5067 (local copy)">). The
5068 latest version, which may be a more recent version, may
5070 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5071 Specific questions about following the standard may be
5072 asked on the <tt>debian-devel</tt> mailing list, or
5073 referred to the FHS mailing list (see the
5074 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5080 <heading>Site-specific programs</heading>
5083 As mandated by the FHS, packages must not place any
5084 files in <file>/usr/local</file>, either by putting them in
5085 the file system archive to be unpacked by <prgn>dpkg</prgn>
5086 or by manipulating them in their maintainer scripts.
5090 However, the package may create empty directories below
5091 <file>/usr/local</file> so that the system administrator knows
5092 where to place site-specific files. These directories
5093 should be removed on package removal if they are
5098 Note, that this applies only to directories <em>below</em>
5099 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5100 Packages must not create sub-directories in the directory
5101 <file>/usr/local</file> itself, except those listed in FHS,
5102 section 4.5. However, you may create directories below
5103 them as you wish. You must not remove any of the
5104 directories listed in 4.5, even if you created them.
5108 Since <file>/usr/local</file> can be mounted read-only from a
5109 remote server, these directories must be created and
5110 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5111 maintainer scripts and not be included in the
5112 <file>.deb</file> archive. These scripts must not fail if
5113 either of these operations fail.
5117 For example, the <tt>emacsen-common</tt> package could
5118 contain something like
5119 <example compact="compact">
5120 if [ ! -e /usr/local/share/emacs ]
5122 if mkdir /usr/local/share/emacs 2>/dev/null
5124 chown root:staff /usr/local/share/emacs
5125 chmod 2775 /usr/local/share/emacs
5129 in its <prgn>postinst</prgn> script, and
5130 <example compact="compact">
5131 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5132 rmdir /usr/local/share/emacs 2>/dev/null || true
5134 in the <prgn>prerm</prgn> script. (Note that this form is
5135 used to ensure that if the script is interrupted, the
5136 directory <file>/usr/local/share/emacs</file> will still be
5141 If you do create a directory in <file>/usr/local</file> for
5142 local additions to a package, you should ensure that
5143 settings in <file>/usr/local</file> take precedence over the
5144 equivalents in <file>/usr</file>.
5148 However, because <file>/usr/local</file> and its contents are
5149 for exclusive use of the local administrator, a package
5150 must not rely on the presence or absence of files or
5151 directories in <file>/usr/local</file> for normal operation.
5155 The <file>/usr/local</file> directory itself and all the
5156 subdirectories created by the package should (by default) have
5157 permissions 2775 (group-writable and set-group-id) and be
5158 owned by <tt>root.staff</tt>.
5163 <heading>The system-wide mail directory</heading>
5165 The system-wide mail directory is <file>/var/mail</file>. This
5166 directory is part of the base system and should not owned
5167 by any particular mail agents. The use of the old
5168 location <file>/var/spool/mail</file> is deprecated, even
5169 though the spool may still be physically located there.
5170 To maintain partial upgrade compatibility for systems
5171 which have <file>/var/spool/mail</file> as their physical mail
5172 spool, packages using <file>/var/mail</file> must depend on
5173 either <package>libc6</package> (>= 2.1.3-13), or on
5174 <package>base-files</package> (>= 2.2.0), or on later
5175 versions of either one of these packages.
5181 <heading>Users and groups</heading>
5184 <heading>Introduction</heading>
5186 The Debian system can be configured to use either plain or
5191 Some user ids (UIDs) and group ids (GIDs) are reserved
5192 globally for use by certain packages. Because some
5193 packages need to include files which are owned by these
5194 users or groups, or need the ids compiled into binaries,
5195 these ids must be used on any Debian system only for the
5196 purpose for which they are allocated. This is a serious
5197 restriction, and we should avoid getting in the way of
5198 local administration policies. In particular, many sites
5199 allocate users and/or local system groups starting at 100.
5203 Apart from this we should have dynamically allocated ids,
5204 which should by default be arranged in some sensible
5205 order, but the behavior should be configurable.
5209 Packages other than <tt>base-passwd</tt> must not modify
5210 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5211 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5216 <heading>UID and GID classes</heading>
5218 The UID and GID numbers are divided into classes as
5224 Globally allocated by the Debian project, the same
5225 on every Debian system. These ids will appear in
5226 the <file>passwd</file> and <file>group</file> files of all
5227 Debian systems, new ids in this range being added
5228 automatically as the <tt>base-passwd</tt> package is
5233 Packages which need a single statically allocated
5234 uid or gid should use one of these; their
5235 maintainers should ask the <tt>base-passwd</tt>
5243 Dynamically allocated system users and groups.
5244 Packages which need a user or group, but can have
5245 this user or group allocated dynamically and
5246 differently on each system, should use <tt>adduser
5247 --system</tt> to create the group and/or user.
5248 <prgn>adduser</prgn> will check for the existence of
5249 the user or group, and if necessary choose an unused
5250 id based on the ranges specified in
5251 <file>adduser.conf</file>.
5255 <tag>1000-29999:</tag>
5258 Dynamically allocated user accounts. By default
5259 <prgn>adduser</prgn> will choose UIDs and GIDs for
5260 user accounts in this range, though
5261 <file>adduser.conf</file> may be used to modify this
5266 <tag>30000-59999:</tag>
5271 <tag>60000-64999:</tag>
5274 Globally allocated by the Debian project, but only
5275 created on demand. The ids are allocated centrally
5276 and statically, but the actual accounts are only
5277 created on users' systems on demand.
5281 These ids are for packages which are obscure or
5282 which require many statically-allocated ids. These
5283 packages should check for and create the accounts in
5284 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5285 <prgn>adduser</prgn> if it has this facility) if
5286 necessary. Packages which are likely to require
5287 further allocations should have a "hole" left after
5288 them in the allocation, to give them room to
5293 <tag>65000-65533:</tag>
5301 User <tt>nobody</tt>. The corresponding gid refers
5302 to the group <tt>nogroup</tt>.
5309 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5310 not</em> be used, because it is the error return
5319 <sect id="sysvinit">
5320 <heading>System run levels and <file>init.d</file> scripts</heading>
5322 <sect1 id="/etc/init.d">
5323 <heading>Introduction</heading>
5326 The <file>/etc/init.d</file> directory contains the scripts
5327 executed by <prgn>init</prgn> at boot time and when the
5328 init state (or "runlevel") is changed (see <manref
5329 name="init" section="8">).
5333 There are at least two different, yet functionally
5334 equivalent, ways of handling these scripts. For the sake
5335 of simplicity, this document describes only the symbolic
5336 link method. However, it must not be assumed by maintainer
5337 scripts that this method is being used, and any automated
5338 manipulation of the various runlevel behaviours by
5339 maintainer scripts must be performed using
5340 <prgn>update-rc.d</prgn> as described below and not by
5341 manually installing or removing symlinks. For information
5342 on the implementation details of the other method,
5343 implemented in the <tt>file-rc</tt> package, please refer
5344 to the documentation of that package.
5348 These scripts are referenced by symbolic links in the
5349 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5350 runlevels, <prgn>init</prgn> looks in the directory
5351 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5352 execute, where <tt><var>n</var></tt> is the runlevel that
5353 is being changed to, or <tt>S</tt> for the boot-up
5358 The names of the links all have the form
5359 <file>S<var>mm</var><var>script</var></file> or
5360 <file>K<var>mm</var><var>script</var></file> where
5361 <var>mm</var> is a two-digit number and <var>script</var>
5362 is the name of the script (this should be the same as the
5363 name of the actual script in <file>/etc/init.d</file>).
5367 When <prgn>init</prgn> changes runlevel first the targets
5368 of the links whose names start with a <tt>K</tt> are
5369 executed, each with the single argument <tt>stop</tt>,
5370 followed by the scripts prefixed with an <tt>S</tt>, each
5371 with the single argument <tt>start</tt>. (The links are
5372 those in the <file>/etc/rc<var>n</var>.d</file> directory
5373 corresponding to the new runlevel.) The <tt>K</tt> links
5374 are responsible for killing services and the <tt>S</tt>
5375 link for starting services upon entering the runlevel.
5379 For example, if we are changing from runlevel 2 to
5380 runlevel 3, init will first execute all of the <tt>K</tt>
5381 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5382 all of the <tt>S</tt> prefixed scripts in that directory.
5383 The links starting with <tt>K</tt> will cause the
5384 referred-to file to be executed with an argument of
5385 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5390 The two-digit number <var>mm</var> is used to determine
5391 the order in which to run the scripts: low-numbered links
5392 have their scripts run first. For example, the
5393 <tt>K20</tt> scripts will be executed before the
5394 <tt>K30</tt> scripts. This is used when a certain service
5395 must be started before another. For example, the name
5396 server <prgn>bind</prgn> might need to be started before
5397 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5398 can set up its access lists. In this case, the script
5399 that starts <prgn>bind</prgn> would have a lower number
5400 than the script that starts <prgn>inn</prgn> so that it
5402 <example compact="compact">
5409 The two runlevels 0 (halt) and 6 (reboot) are slightly
5410 different. In these runlevels, the links with an
5411 <tt>S</tt> prefix are still called after those with a
5412 <tt>K</tt> prefix, but they too are called with the single
5413 argument <tt>stop</tt>.
5417 Also, if the script name ends <tt>.sh</tt>, the script
5418 will be sourced in runlevel <tt>S</tt> rather that being
5419 run in a forked subprocess, but will be explicitly run by
5420 <prgn>sh</prgn> in all other runlevels.
5425 <heading>Writing the scripts</heading>
5428 Packages that include daemons for system services should
5429 place scripts in <file>/etc/init.d</file> to start or stop
5430 services at boot time or during a change of runlevel.
5431 These scripts should be named
5432 <file>/etc/init.d/<var>package</var></file>, and they should
5433 accept one argument, saying what to do:
5436 <tag><tt>start</tt></tag>
5437 <item>start the service,</item>
5439 <tag><tt>stop</tt></tag>
5440 <item>stop the service,</item>
5442 <tag><tt>restart</tt></tag>
5443 <item>stop and restart the service if it's already running,
5444 otherwise start the service</item>
5446 <tag><tt>reload</tt></tag>
5447 <item><p>cause the configuration of the service to be
5448 reloaded without actually stopping and restarting
5451 <tag><tt>force-reload</tt></tag>
5452 <item>cause the configuration to be reloaded if the
5453 service supports this, otherwise restart the
5457 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5458 <tt>force-reload</tt> options should be supported by all
5459 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5464 The <file>init.d</file> scripts should ensure that they will
5465 behave sensibly if invoked with <tt>start</tt> when the
5466 service is already running, or with <tt>stop</tt> when it
5467 isn't, and that they don't kill unfortunately-named user
5468 processes. The best way to achieve this is usually to use
5469 <prgn>start-stop-daemon</prgn>.
5473 If a service reloads its configuration automatically (as
5474 in the case of <prgn>cron</prgn>, for example), the
5475 <tt>reload</tt> option of the <file>init.d</file> script
5476 should behave as if the configuration has been reloaded
5481 The <file>/etc/init.d</file> scripts must be treated as
5482 configuration files, either (if they are present in the
5483 package, that is, in the .deb file) by marking them as
5484 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5485 by managing them correctly in the maintainer scripts (see
5486 <ref id="config-files">). This is important since we want
5487 to give the local system administrator the chance to adapt
5488 the scripts to the local system, e.g., to disable a
5489 service without de-installing the package, or to specify
5490 some special command line options when starting a service,
5491 while making sure their changes aren't lost during the next
5496 These scripts should not fail obscurely when the
5497 configuration files remain but the package has been
5498 removed, as configuration files remain on the system after
5499 the package has been removed. Only when <prgn>dpkg</prgn>
5500 is executed with the <tt>--purge</tt> option will
5501 configuration files be removed. In particular, as the
5502 <file>/etc/init.d/<var>package</var></file> script itself is
5503 usually a <tt>conffile</tt>, it will remain on the system
5504 if the package is removed but not purged. Therefore, you
5505 should include a <tt>test</tt> statement at the top of the
5507 <example compact="compact">
5508 test -f <var>program-executed-later-in-script</var> || exit 0
5513 Often there are some variables in the <file>init.d</file>
5514 scripts whose values control the behaviour of the scripts,
5515 and which a system administrator is likely to want to
5516 change. As the scripts themselves are frequently
5517 <tt>conffile</tt>s, modifying them requires that the
5518 administrator merge in their changes each time the package
5519 is upgraded and the <tt>conffile</tt> changes. To ease
5520 the burden on the system administrator, such configurable
5521 values should not be placed directly in the script.
5522 Instead, they should be placed in a file in
5523 <file>/etc/default</file>, which typically will have the same
5524 base name as the <file>init.d</file> script. This extra file
5525 should be sourced by the script when the script runs. It
5526 must contain only variable settings and comments in POSIX
5527 <prgn>sh</prgn> format. It may either be a
5528 <tt>conffile</tt> or a configuration file maintained by
5529 the package maintainer scripts. See <ref id="config-files">
5534 To ensure that vital configurable values are always
5535 available, the <file>init.d</file> script should set default
5536 values for each of the shell variables it uses, either
5537 before sourcing the <file>/etc/default/</file> file or
5538 afterwards using something like the <tt>:
5539 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5540 script must behave sensibly and not fail if the
5541 <file>/etc/default</file> file is deleted.
5546 <heading>Interfacing with the initscript system</heading>
5549 Maintainers should use the abstraction layer provided by
5550 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5551 programs to deal with initscripts in their packages'
5552 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5553 and <prgn>postrm</prgn>.
5557 Directly managing the /etc/rc?.d links and directly
5558 invoking the <file>/etc/init.d/</file> initscripts should
5559 be done only by packages providing the initscript
5560 subsystem (such as <prgn>sysv-rc</prgn> and
5561 <prgn>file-rc</prgn>).
5565 <heading>Managing the links</heading>
5568 The program <prgn>update-rc.d</prgn> is provided for
5569 package maintainers to arrange for the proper creation and
5570 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5571 or their functional equivalent if another method is being
5572 used. This may be used by maintainers in their packages'
5573 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5577 You must not include any <file>/etc/rc<var>n</var>.d</file>
5578 symbolic links in the actual archive or manually create or
5579 remove the symbolic links in maintainer scripts; you must
5580 use the <prgn>update-rc.d</prgn> program instead. (The
5581 former will fail if an alternative method of maintaining
5582 runlevel information is being used.) You must not include
5583 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5584 in the archive either. (Only the <tt>sysvinit</tt>
5589 By default <prgn>update-rc.d</prgn> will start services in
5590 each of the multi-user state runlevels (2, 3, 4, and 5)
5591 and stop them in the halt runlevel (0), the single-user
5592 runlevel (1) and the reboot runlevel (6). The system
5593 administrator will have the opportunity to customize
5594 runlevels by simply adding, moving, or removing the
5595 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5596 symbolic links are being used, or by modifying
5597 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5602 To get the default behavior for your package, put in your
5603 <prgn>postinst</prgn> script
5604 <example compact="compact">
5605 update-rc.d <var>package</var> defaults
5607 and in your <prgn>postrm</prgn>
5608 <example compact="compact">
5609 if [ "$1" = purge ]; then
5610 update-rc.d <var>package</var> remove
5612 </example>. Note that if your package changes runlevels
5613 or priority, you may have to remove and recreate the links,
5614 since otherwise the old links may persist. Refer to the
5615 documentation of <prgn>update-rc.d</prgn>.
5619 This will use a default sequence number of 20. If it does
5620 not matter when or in which order the <file>init.d</file>
5621 script is run, use this default. If it does, then you
5622 should talk to the maintainer of the <prgn>sysvinit</prgn>
5623 package or post to <tt>debian-devel</tt>, and they will
5624 help you choose a number.
5628 For more information about using <tt>update-rc.d</tt>,
5629 please consult its man page <manref name="update-rc.d"
5635 <heading>Running initscripts</heading>
5637 The program <prgn>invoke-rc.d</prgn> is provided to make
5638 it easier for package maintainers to properly invoke an
5639 initscript, obeying runlevel and other locally-defined
5640 constraints that might limit a package's right to start,
5641 stop and otherwise manage services. This program may be
5642 used by maintainers in their packages' scripts.
5646 The use of <prgn>invoke-rc.d</prgn> to invoke the
5647 <file>/etc/init.d/*</file> initscripts is strongly
5648 recommended<footnote>
5649 In the future, the use of invoke-rc.d to invoke
5650 initscripts shall be made mandatory. Maintainers are
5651 advised to switch to invoke-rc.d as soon as
5653 </footnote>, instead of calling them directly.
5657 By default, <prgn>invoke-rc.d</prgn> will pass any
5658 action requests (start, stop, reload, restart...) to the
5659 <file>/etc/init.d</file> script, filtering out requests
5660 to start or restart a service out of its intended
5665 Most packages will simply need to change:
5666 <example compact="compact">/etc/init.d/<package>
5667 <action></example> in their <prgn>postinst</prgn>
5668 and <prgn>prerm</prgn> scripts to:
5669 <example compact="compact">
5670 if which invoke-rc.d >/dev/null 2>&1; then
5671 invoke-rc.d <var>package</var> <action>
5673 /etc/init.d/<var>package</var> <action>
5679 A package should register its initscript services using
5680 <prgn>update-rc.d</prgn> before it tries to invoke them
5681 using <prgn>invoke-rc.d</prgn>. Invocation of
5682 unregistered services may fail.
5686 For more information about using
5687 <prgn>invoke-rc.d</prgn>, please consult its man page
5688 <manref name="invoke-rc.d" section="8">.
5694 <heading>Boot-time initialization</heading>
5697 There used to be another directory, <file>/etc/rc.boot</file>,
5698 which contained scripts which were run once per machine
5699 boot. This has been deprecated in favour of links from
5700 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5701 described in <ref id="/etc/init.d">. Packages must not
5702 place files in <file>/etc/rc.boot</file>.
5707 <heading>Example</heading>
5710 The <prgn>bind</prgn> DNS (nameserver) package wants to
5711 make sure that the nameserver is running in multiuser
5712 runlevels, and is properly shut down with the system. It
5713 puts a script in <file>/etc/init.d</file>, naming the script
5714 appropriately <tt>bind</tt>. As you can see, the script
5715 interprets the argument <tt>reload</tt> to send the
5716 nameserver a <tt>HUP</tt> signal (causing it to reload its
5717 configuration); this way the system administrator can say
5718 <tt>/etc/init.d/bind reload</tt> to reload the name
5719 server. The script has one configurable value, which can
5720 be used to pass parameters to the named program at
5721 startup; this value is read from
5722 <file>/etc/default/bind</file> (see below).
5726 <example compact="compact">
5729 # Original version by Robert Leslie
5730 # <rob@mars.org>, edited by iwj and cs
5732 test -x /usr/sbin/named || exit 0
5734 # Source defaults file.
5736 if [ -f /etc/default/bind ]; then
5743 echo -n "Starting domain name service: named"
5744 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5749 echo -n "Stopping domain name service: named"
5750 start-stop-daemon --stop --quiet \
5751 --pidfile /var/run/named.pid --exec /usr/sbin/named
5755 echo -n "Restarting domain name service: named"
5756 start-stop-daemon --stop --quiet --oknodo \
5757 --pidfile /var/run/named.pid --exec /usr/sbin/named
5758 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5762 force-reload|reload)
5763 echo -n "Reloading configuration of domain name service: named"
5764 start-stop-daemon --stop --signal 1 --quiet \
5765 --pidfile /var/run/named.pid --exec /usr/sbin/named
5769 echo "Usage: /etc/init.d/bind " \
5770 " {start|stop|restart|reload|force-reload}" >&2
5780 Complementing the above init script is a configuration
5781 file <file>/etc/default/bind</file>, which contains
5782 configurable parameters used by the script. This would be
5783 created by the <prgn>postinst</prgn> script if it was not
5784 already present, and removed on purge by the
5785 <prgn>postrm</prgn> script.
5786 <example compact="compact">
5787 # Specified parameters to pass to named. See named(8).
5788 # You may uncomment the following line, and edit to taste.
5794 Another example on which you can base your
5795 <file>/etc/init.d</file> scripts is found in
5796 <file>/etc/init.d/skeleton</file>.
5800 If this package is happy with the default setup from
5801 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5802 and having named running in all runlevels, it can say in
5803 its <prgn>postinst</prgn>:
5804 <example compact="compact">
5805 update-rc.d bind defaults >/dev/null
5807 And in its <prgn>postrm</prgn>, to remove the links when the
5809 <example compact="compact">
5810 if [ "$1" = purge ]; then
5811 update-rc.d bind remove >/dev/null
5819 <heading>Console messages from <file>init.d</file> scripts</heading>
5822 This section describes the formats to be used for messages
5823 written to standard output by the <file>/etc/init.d</file>
5824 scripts. The intent is to improve the consistency of
5825 Debian's startup and shutdown look and feel. For this
5826 reason, please look very carefully at the details. We want
5827 the messages to have the same format in terms of wording,
5828 spaces, punctuation and case of letters.
5832 Here is a list of overall rules that should be used for
5833 messages generated by <file>/etc/init.d</file> scripts.
5839 The message should fit in one line (fewer than 80
5840 characters), start with a capital letter and end with
5841 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5845 If the script is performing some time consuming task in
5846 the background (not merely starting or stopping a
5847 program, for instance), an ellipsis (three dots:
5848 <tt>...</tt>) should be output to the screen, with no
5849 leading or tailing whitespace or line feeds.
5853 The messages should appear as if the computer is telling
5854 the user what it is doing (politely :-), but should not
5855 mention "it" directly. For example, instead of:
5856 <example compact="compact">
5857 I'm starting network daemons: nfsd mountd.
5859 the message should say
5860 <example compact="compact">
5861 Starting network daemons: nfsd mountd.
5868 <tt>init.d</tt> script should use the following standard
5869 message formats for the situations enumerated below.
5875 <p>When daemons are started</p>
5878 If the script starts one or more daemons, the output
5879 should look like this (a single line, no leading
5881 <example compact="compact">
5882 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5884 The <var>description</var> should describe the
5885 subsystem the daemon or set of daemons are part of,
5886 while <var>daemon-1</var> up to <var>daemon-n</var>
5887 denote each daemon's name (typically the file name of
5892 For example, the output of <file>/etc/init.d/lpd</file>
5894 <example compact="compact">
5895 Starting printer spooler: lpd.
5900 This can be achieved by saying
5901 <example compact="compact">
5902 echo -n "Starting printer spooler: lpd"
5903 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5906 in the script. If there are more than one daemon to
5907 start, the output should look like this:
5908 <example compact="compact">
5909 echo -n "Starting remote file system services:"
5910 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5911 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5912 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5915 This makes it possible for the user to see what is
5916 happening and when the final daemon has been started.
5917 Care should be taken in the placement of white spaces:
5918 in the example above the system administrators can
5919 easily comment out a line if they don't want to start
5920 a specific daemon, while the displayed message still
5926 <p>When a system parameter is being set</p>
5929 If you have to set up different system parameters
5930 during the system boot, you should use this format:
5931 <example compact="compact">
5932 Setting <var>parameter</var> to "<var>value</var>".
5937 You can use a statement such as the following to get
5939 <example compact="compact">
5940 echo "Setting DNS domainname to \"$domainname\"."
5945 Note that the same symbol (<tt>"</tt>) is used for the left
5946 and right quotation marks. A grave accent (<tt>`</tt>) is
5947 not a quote character; neither is an apostrophe
5953 <p>When a daemon is stopped or restarted</p>
5956 When you stop or restart a daemon, you should issue a
5957 message identical to the startup message, except that
5958 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5959 or <tt>Restarting</tt> respectively.
5963 For example, stopping the printer daemon will like
5965 <example compact="compact">
5966 Stopping printer spooler: lpd.
5972 <p>When something is executed</p>
5975 There are several examples where you have to run a
5976 program at system startup or shutdown to perform a
5977 specific task, for example, setting the system's clock
5978 using <prgn>netdate</prgn> or killing all processes
5979 when the system shuts down. Your message should look
5981 <example compact="compact">
5982 Doing something very useful...done.
5984 You should print the <tt>done.</tt> immediately after
5985 the job has been completed, so that the user is
5986 informed why they have to wait. You can get this
5988 <example compact="compact">
5989 echo -n "Doing something very useful..."
5998 <p>When the configuration is reloaded</p>
6001 When a daemon is forced to reload its configuration
6002 files you should use the following format:
6003 <example compact="compact">
6004 Reloading <var>description</var> configuration...done.
6006 where <var>description</var> is the same as in the
6007 daemon starting message.
6015 <heading>Cron jobs</heading>
6018 Packages must not modify the configuration file
6019 <file>/etc/crontab</file>, and they must not modify the files in
6020 <file>/var/spool/cron/crontabs</file>.</p>
6023 If a package wants to install a job that has to be executed
6024 via cron, it should place a file with the name of the
6025 package in one or more of the following directories:
6026 <example compact="compact">
6031 As these directory names imply, the files within them are
6032 executed on a daily, weekly, or monthly basis,
6033 respectively. The exact times are listed in
6034 <file>/etc/crontab</file>.</p>
6037 All files installed in any of these directories must be
6038 scripts (e.g., shell scripts or Perl scripts) so that they
6039 can easily be modified by the local system administrator.
6040 In addition, they should be treated as configuration
6045 If a certain job has to be executed more frequently than
6046 daily, the package should install a file
6047 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6048 same syntax as <file>/etc/crontab</file> and is processed by
6049 <prgn>cron</prgn> automatically. The file must also be
6050 treated as a configuration file. (Note that entries in the
6051 <file>/etc/cron.d</file> directory are not handled by
6052 <prgn>anacron</prgn>. Thus, you should only use this
6053 directory for jobs which may be skipped if the system is not
6057 The scripts or crontab entries in these directories should
6058 check if all necessary programs are installed before they
6059 try to execute them. Otherwise, problems will arise when a
6060 package was removed but not purged since configuration files
6061 are kept on the system in this situation.</p>
6065 <heading>Menus</heading>
6068 The Debian <tt>menu</tt> package provides a standard
6069 interface between packages providing applications and
6070 <em>menu programs</em> (either X window managers or
6071 text-based menu programs such as <prgn>pdmenu</prgn>).
6075 All packages that provide applications that need not be
6076 passed any special command line arguments for normal
6077 operation should register a menu entry for those
6078 applications, so that users of the <tt>menu</tt> package
6079 will automatically get menu entries in their window
6080 managers, as well in shells like <tt>pdmenu</tt>.
6084 Menu entries should follow the current menu policy.
6088 The menu policy can be found in the <tt>menu-policy</tt>
6089 files in the <tt>debian-policy</tt> package.
6090 It is also available from the Debian web mirrors at
6091 <tt><url name="/doc/packaging-manuals/menu-policy/"
6092 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6096 Please also refer to the <em>Debian Menu System</em>
6097 documentation that comes with the <package>menu</package>
6098 package for information about how to register your
6104 <heading>Multimedia handlers</heading>
6107 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6108 is a mechanism for encoding files and data streams and
6109 providing meta-information about them, in particular their
6110 type (e.g. audio or video) and format (e.g. PNG, HTML,
6115 Registration of MIME type handlers allows programs like mail
6116 user agents and web browsers to invoke these handlers to
6117 view, edit or display MIME types they don't support directly.
6121 Packages which provide the ability to view/show/play,
6122 compose, edit or print MIME types should register themselves
6123 as such following the current MIME support policy.
6127 The MIME support policy can be found in the <tt>mime-policy</tt>
6128 files in the <tt>debian-policy</tt> package.
6129 It is also available from the Debian web mirrors at
6130 <tt><url name="/doc/packaging-manuals/mime-policy/"
6131 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6137 <heading>Keyboard configuration</heading>
6140 To achieve a consistent keyboard configuration so that all
6141 applications interpret a keyboard event the same way, all
6142 programs in the Debian distribution must be configured to
6143 comply with the following guidelines.
6147 The following keys must have the specified interpretations:
6150 <tag><tt><--</tt></tag>
6151 <item>delete the character to the left of the cursor</item>
6153 <tag><tt>Delete</tt></tag>
6154 <item>delete the character to the right of the cursor</item>
6156 <tag><tt>Control+H</tt></tag>
6157 <item>emacs: the help prefix</item>
6160 The interpretation of any keyboard events should be
6161 independent of the terminal that is used, be it a virtual
6162 console, an X terminal emulator, an rlogin/telnet session,
6167 The following list explains how the different programs
6168 should be set up to achieve this:
6174 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6178 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6182 X translations are set up to make
6183 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6184 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6185 is the vt220 escape code for the "delete character"
6186 key). This must be done by loading the X resources
6187 using <prgn>xrdb</prgn> on all local X displays, not
6188 using the application defaults, so that the
6189 translation resources used correspond to the
6190 <prgn>xmodmap</prgn> settings.
6194 The Linux console is configured to make
6195 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6196 generate <tt>ESC [ 3 ~</tt>.
6200 X applications are configured so that <tt><</tt>
6201 deletes left, and <tt>Delete</tt> deletes right. Motif
6202 applications already work like this.
6206 Terminals should have <tt>stty erase ^?</tt> .
6210 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6211 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6212 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6216 Emacs is programmed to map <tt>KB_Backspace</tt> or
6217 the <tt>stty erase</tt> character to
6218 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6219 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6220 <tt>^H</tt> to <tt>help</tt> as always.
6224 Other applications use the <tt>stty erase</tt>
6225 character and <tt>kdch1</tt> for the two delete keys,
6226 with ASCII DEL being "delete previous character" and
6227 <tt>kdch1</tt> being "delete character under
6235 This will solve the problem except for the following
6242 Some terminals have a <tt><--</tt> key that cannot
6243 be made to produce anything except <tt>^H</tt>. On
6244 these terminals Emacs help will be unavailable on
6245 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6246 character takes precedence in Emacs, and has been set
6247 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6248 available) can be used instead.
6252 Some operating systems use <tt>^H</tt> for <tt>stty
6253 erase</tt>. However, modern telnet versions and all
6254 rlogin versions propagate <tt>stty</tt> settings, and
6255 almost all UNIX versions honour <tt>stty erase</tt>.
6256 Where the <tt>stty</tt> settings are not propagated
6257 correctly, things can be made to work by using
6258 <tt>stty</tt> manually.
6262 Some systems (including previous Debian versions) use
6263 <prgn>xmodmap</prgn> to arrange for both
6264 <tt><--</tt> and <tt>Delete</tt> to generate
6265 <tt>KB_Delete</tt>. We can change the behavior of
6266 their X clients using the same X resources that we use
6267 to do it for our own clients, or configure our clients
6268 using their resources when things are the other way
6269 around. On displays configured like this
6270 <tt>Delete</tt> will not work, but <tt><--</tt>
6275 Some operating systems have different <tt>kdch1</tt>
6276 settings in their <tt>terminfo</tt> database for
6277 <tt>xterm</tt> and others. On these systems the
6278 <tt>Delete</tt> key will not work correctly when you
6279 log in from a system conforming to our policy, but
6280 <tt><--</tt> will.
6287 <heading>Environment variables</heading>
6290 A program must not depend on environment variables to get
6291 reasonable defaults. (That's because these environment
6292 variables would have to be set in a system-wide
6293 configuration file like <file>/etc/profile</file>, which is not
6294 supported by all shells.)
6298 If a program usually depends on environment variables for its
6299 configuration, the program should be changed to fall back to
6300 a reasonable default configuration if these environment
6301 variables are not present. If this cannot be done easily
6302 (e.g., if the source code of a non-free program is not
6303 available), the program must be replaced by a small
6304 "wrapper" shell script which sets the environment variables
6305 if they are not already defined, and calls the original program.
6309 Here is an example of a wrapper script for this purpose:
6311 <example compact="compact">
6313 BAR=${BAR:-/var/lib/fubar}
6315 exec /usr/lib/foo/foo "$@"
6320 Furthermore, as <file>/etc/profile</file> is a configuration
6321 file of the <prgn>base-files</prgn> package, other packages must
6322 not put any environment variables or other commands into that
6327 <sect id="doc-base">
6328 <heading>Registering Documents using doc-base</heading>
6331 The <package>doc-base</package> package implements a
6332 flexible mechanism for handling and presenting
6333 documentation. The recommended practice is for every Debian
6334 package that provides online documentation (other than just
6335 manual pages) to register these documents with
6336 <package>doc-base</package> by installing a
6337 <package>doc-base</package> control file via the
6338 <prgn/install-docs/ script at installation time and
6339 de-register the manuals again when the package is removed.
6342 Please refer to the documentation that comes with the
6343 <package>doc-base</package> package for information and
6352 <heading>Files</heading>
6355 <heading>Binaries</heading>
6358 Two different packages must not install programs with
6359 different functionality but with the same filenames. (The
6360 case of two programs having the same functionality but
6361 different implementations is handled via "alternatives" or
6362 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6363 <ref id="conflicts"> respectively.) If this case happens,
6364 one of the programs must be renamed. The maintainers should
6365 report this to the <tt>debian-devel</tt> mailing list and
6366 try to find a consensus about which program will have to be
6367 renamed. If a consensus cannot be reached, <em>both</em>
6368 programs must be renamed.
6372 By default, when a package is being built, any binaries
6373 created should include debugging information, as well as
6374 being compiled with optimization. You should also turn on
6375 as many reasonable compilation warnings as possible; this
6376 makes life easier for porters, who can then look at build
6377 logs for possible problems. For the C programming language,
6378 this means the following compilation parameters should be
6380 <example compact="compact">
6382 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6384 install -s # (or use strip on the files in debian/tmp)
6389 Note that by default all installed binaries should be stripped,
6390 either by using the <tt>-s</tt> flag to
6391 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6392 the binaries after they have been copied into
6393 <file>debian/tmp</file> but before the tree is made into a
6398 Although binaries in the build tree should be compiled with
6399 debugging information by default, it can often be difficult
6400 to debug programs if they are also subjected to compiler
6401 optimization. For this reason, it is recommended to support
6402 the standardized environment
6403 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6404 contain several flags to change how a package is compiled
6412 The presence of this string means that the package
6413 should be compiled with a minimum of optimization.
6414 For C programs, it is best to add <tt>-O0</tt>
6415 to <tt>CFLAGS</tt> (although this is usually the
6416 default). Some programs might fail to build or run at
6417 this level of optimization; it may be necessary to
6418 use <tt>-O1</tt>, for example.
6422 This string means that the debugging symbols should
6423 not be stripped from the binary during installation,
6424 so that debugging information may be included in the package.
6430 The following makefile snippet is an example of how one may
6431 implement the build options; you will probably have to
6432 massage this example in order to make it work for your
6434 <example compact="compact">
6437 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6438 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6439 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6440 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6442 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6447 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6448 INSTALL_PROGRAM += -s
6454 It is up to the package maintainer to decide what
6455 compilation options are best for the package. Certain
6456 binaries (such as computationally-intensive programs) will
6457 function better with certain flags (<tt>-O3</tt>, for
6458 example); feel free to use them. Please use good judgment
6459 here. Don't use flags for the sake of it; only use them
6460 if there is good reason to do so. Feel free to override
6461 the upstream author's ideas about which compilation
6462 options are best: they are often inappropriate for our
6468 <sect id="libraries">
6469 <heading>Libraries</heading>
6472 The shared version of a library must be compiled with
6473 <tt>-fPIC</tt>, and the static version must not be. In other
6474 words, each source unit (<tt>*.c</tt>, for example, for C files)
6475 will need to be compiled twice.
6479 You must specify the gcc option <tt>-D_REENTRANT</tt>
6480 when building a library (either static or shared) to make
6481 the library compatible with LinuxThreads.
6485 Although not enforced by the build tools, shared libraries
6486 must be linked against all libraries that they use symbols from
6487 in the same way that binaries are. This ensures the correct
6488 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6489 system and guarantees that all libraries can be safely opened
6490 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6491 option <tt>-Wl,-z,defs</tt> when building a shared library.
6492 Since this option enforces symbol resolution at build time,
6493 a missing library reference will be caught early as a fatal
6498 All installed shared libraries should be stripped with
6499 <example compact="compact">
6500 strip --strip-unneeded <var>your-lib</var>
6502 (The option <tt>--strip-unneeded</tt> makes
6503 <prgn>strip</prgn> remove only the symbols which aren't
6504 needed for relocation processing.) Shared libraries can
6505 function perfectly well when stripped, since the symbols for
6506 dynamic linking are in a separate part of the ELF object
6508 You might also want to use the options
6509 <tt>--remove-section=.comment</tt> and
6510 <tt>--remove-section=.note</tt> on both shared libraries
6511 and executables, and <tt>--strip-debug</tt> on static
6517 Note that under some circumstances it may be useful to
6518 install a shared library unstripped, for example when
6519 building a separate package to support debugging.
6523 Shared object files (often <file>.so</file> files) that are not
6524 public libraries, that is, they are not meant to be linked
6525 to by third party executables (binaries of other packages),
6526 should be installed in subdirectories of the
6527 <file>/usr/lib</file> directory. Such files are exempt from the
6528 rules that govern ordinary shared libraries, except that
6529 they must not be installed executable and should be
6531 A common example are the so-called "plug-ins",
6532 internal shared objects that are dynamically loaded by
6533 programs using <manref name="dlopen" section="3">.
6538 Packages containing shared libraries that may be linked to
6539 by other packages' binaries, but which for some
6540 <em>compelling</em> reason can not be installed in
6541 <file>/usr/lib</file> directory, may install the shared library
6542 files in subdirectories of the <file>/usr/lib</file> directory,
6543 in which case they should arrange to add that directory in
6544 <file>/etc/ld.so.conf</file> in the package's post-installation
6545 script, and remove it in the package's post-removal script.
6549 An ever increasing number of packages are using
6550 <prgn>libtool</prgn> to do their linking. The latest GNU
6551 libtools (>= 1.3a) can take advantage of the metadata in the
6552 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6553 files). The main advantage of <prgn>libtool</prgn>'s
6554 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6555 store and subsequently access metadata with respect to the
6556 libraries it builds. <prgn>libtool</prgn> will search for
6557 those files, which contain a lot of useful information about
6558 a library (such as library dependency information for static
6559 linking). Also, they're <em>essential</em> for programs
6560 using <tt>libltdl</tt>.<footnote>
6561 Although <prgn>libtool</prgn> is fully capable of
6562 linking against shared libraries which don't have
6563 <tt>.la</tt> files, as it is a mere shell script it can
6564 add considerably to the build time of a
6565 <prgn>libtool</prgn>-using package if that shell script
6566 has to derive all this information from first principles
6567 for each library every time it is linked. With the
6568 advent of <prgn>libtool</prgn> version 1.4 (and to a
6569 lesser extent <prgn>libtool</prgn> version 1.3), the
6570 <file>.la</file> files also store information about
6571 inter-library dependencies which cannot necessarily be
6572 derived after the <file>.la</file> file is deleted.
6577 Packages that use <prgn>libtool</prgn> to create shared
6578 libraries should include the <file>.la</file> files in the
6579 <tt>-dev</tt> package, unless the package relies on
6580 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6581 the <tt>.la</tt> files must go in the run-time library
6586 You must make sure that you use only released versions of
6587 shared libraries to build your packages; otherwise other
6588 users will not be able to run your binaries
6589 properly. Producing source packages that depend on
6590 unreleased compilers is also usually a bad
6597 <heading>Shared libraries</heading>
6599 This section has moved to <ref id="sharedlibs">.
6605 <heading>Scripts</heading>
6608 All command scripts, including the package maintainer
6609 scripts inside the package and used by <prgn>dpkg</prgn>,
6610 should have a <tt>#!</tt> line naming the shell to be used
6615 In the case of Perl scripts this should be
6616 <tt>#!/usr/bin/perl</tt>.
6620 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6621 should almost certainly start with <tt>set -e</tt> so that
6622 errors are detected. Every script should use
6623 <tt>set -e</tt> or check the exit status of <em>every</em>
6628 The standard shell interpreter <file>/bin/sh</file> can be a
6629 symbolic link to any POSIX compatible shell, if <tt>echo
6630 -n</tt> does not generate a newline.<footnote>
6631 Debian policy specifies POSIX behavior for
6632 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6633 use in the Linux community (in particular including this
6634 policy, the Linux kernel source, many Debian scripts,
6635 etc.). This <tt>echo -n</tt> mechanism is valid but not
6636 required under POSIX, hence this explicit addition.
6637 Also, rumour has it that this shall be mandated under
6640 Thus, shell scripts specifying <file>/bin/sh</file> as
6641 interpreter should only use POSIX features. If a script
6642 requires non-POSIX features from the shell interpreter, the
6643 appropriate shell must be specified in the first line of the
6644 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6645 depend on the package providing the shell (unless the shell
6646 package is marked "Essential", as in the case of
6651 You may wish to restrict your script to POSIX features when
6652 possible so that it may use <file>/bin/sh</file> as its
6653 interpreter. If your script works with <prgn>dash</prgn>
6654 (originally called <prgn>ash</prgn>), it's probably POSIX
6655 compliant, but if you are in doubt, use
6656 <file>/bin/bash</file>.
6660 Perl scripts should check for errors when making any
6661 system calls, including <tt>open</tt>, <tt>print</tt>,
6662 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6666 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6667 scripting languages. See <em>Csh Programming Considered
6668 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6669 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
6670 If an upstream package comes with <prgn>csh</prgn> scripts
6671 then you must make sure that they start with
6672 <tt>#!/bin/csh</tt> and make your package depend on the
6673 <prgn>c-shell</prgn> virtual package.
6677 Any scripts which create files in world-writeable
6678 directories (e.g., in <file>/tmp</file>) must use a
6679 mechanism which will fail if a file with the same name
6684 The Debian base system provides the <prgn>tempfile</prgn>
6685 and <prgn>mktemp</prgn> utilities for use by scripts for
6692 <heading>Symbolic links</heading>
6695 In general, symbolic links within a top-level directory
6696 should be relative, and symbolic links pointing from one
6697 top-level directory into another should be absolute. (A
6698 top-level directory is a sub-directory of the root
6699 directory <file>/</file>.)
6703 In addition, symbolic links should be specified as short as
6704 possible, i.e., link targets like <file>foo/../bar</file> are
6709 Note that when creating a relative link using
6710 <prgn>ln</prgn> it is not necessary for the target of the
6711 link to exist relative to the working directory you're
6712 running <prgn>ln</prgn> from, nor is it necessary to change
6713 directory to the directory where the link is to be made.
6714 Simply include the string that should appear as the target
6715 of the link (this will be a pathname relative to the
6716 directory in which the link resides) as the first argument
6721 For example, in your <prgn>Makefile</prgn> or
6722 <file>debian/rules</file>, you can do things like:
6723 <example compact="compact">
6724 ln -fs gcc $(prefix)/bin/cc
6725 ln -fs gcc debian/tmp/usr/bin/cc
6726 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6727 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6732 A symbolic link pointing to a compressed file should always
6733 have the same file extension as the referenced file. (For
6734 example, if a file <file>foo.gz</file> is referenced by a
6735 symbolic link, the filename of the link has to end with
6736 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6741 <heading>Device files</heading>
6744 Packages must not include device files in the package file
6749 If a package needs any special device files that are not
6750 included in the base system, it must call
6751 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6752 after notifying the user<footnote>
6753 This notification could be done via a (low-priority)
6754 debconf message, or an echo (printf) statement.
6759 Packages must not remove any device files in the
6760 <prgn>postrm</prgn> or any other script. This is left to the
6761 system administrator.
6765 Debian uses the serial devices
6766 <file>/dev/ttyS*</file>. Programs using the old
6767 <file>/dev/cu*</file> devices should be changed to use
6768 <file>/dev/ttyS*</file>.
6772 <sect id="config-files">
6773 <heading>Configuration files</heading>
6776 <heading>Definitions</heading>
6780 <tag>configuration file</tag>
6782 A file that affects the operation of a program, or
6783 provides site- or host-specific information, or
6784 otherwise customizes the behavior of a program.
6785 Typically, configuration files are intended to be
6786 modified by the system administrator (if needed or
6787 desired) to conform to local policy or to provide
6788 more useful site-specific behavior.
6791 <tag><tt>conffile</tt></tag>
6793 A file listed in a package's <tt>conffiles</tt>
6794 file, and is treated specially by <prgn>dpkg</prgn>
6795 (see <ref id="configdetails">).
6801 The distinction between these two is important; they are
6802 not interchangeable concepts. Almost all
6803 <tt>conffile</tt>s are configuration files, but many
6804 configuration files are not <tt>conffiles</tt>.
6808 Note that a script that embeds configuration information
6809 (such as most of the files in <file>/etc/default</file> and
6810 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6811 configuration file and should be treated as such.
6816 <heading>Location</heading>
6819 Any configuration files created or used by your package
6820 must reside in <file>/etc</file>. If there are several,
6821 consider creating a subdirectory of <file>/etc</file>
6822 named after your package.
6826 If your package creates or uses configuration files
6827 outside of <file>/etc</file>, and it is not feasible to modify
6828 the package to use <file>/etc</file> directly, put the files
6829 in <file>/etc</file> and create symbolic links to those files
6830 from the location that the package requires.
6835 <heading>Behavior</heading>
6838 Configuration file handling must conform to the following
6840 <list compact="compact">
6842 local changes must be preserved during a package
6846 configuration files must be preserved when the
6847 package is removed, and only deleted when the
6854 The easy way to achieve this behavior is to make the
6855 configuration file a <tt>conffile</tt>. This is
6856 appropriate only if it is possible to distribute a default
6857 version that will work for most installations, although
6858 some system administrators may choose to modify it. This
6859 implies that the default version will be part of the
6860 package distribution, and must not be modified by the
6861 maintainer scripts during installation (or at any other
6866 In order to ensure that local changes are preserved
6867 correctly, no package may contain or make hard links to
6868 conffiles.<footnote>
6869 Rationale: There are two problems with hard links.
6870 The first is that some editors break the link while
6871 editing one of the files, so that the two files may
6872 unwittingly become unlinked and different. The second
6873 is that <prgn>dpkg</prgn> might break the hard link
6874 while upgrading <tt>conffile</tt>s.
6879 The other way to do it is via the maintainer scripts. In
6880 this case, the configuration file must not be listed as a
6881 <tt>conffile</tt> and must not be part of the package
6882 distribution. If the existence of a file is required for
6883 the package to be sensibly configured it is the
6884 responsibility of the package maintainer to provide
6885 maintainer scripts which correctly create, update and
6886 maintain the file and remove it on purge. (See <ref
6887 id="maintainerscripts"> for more information.) These
6888 scripts must be idempotent (i.e., must work correctly if
6889 <prgn>dpkg</prgn> needs to re-run them due to errors
6890 during installation or removal), must cope with all the
6891 variety of ways <prgn>dpkg</prgn> can call maintainer
6892 scripts, must not overwrite or otherwise mangle the user's
6893 configuration without asking, must not ask unnecessary
6894 questions (particularly during upgrades), and otherwise be
6899 The scripts are not required to configure every possible
6900 option for the package, but only those necessary to get
6901 the package running on a given system. Ideally the
6902 sysadmin should not have to do any configuration other
6903 than that done (semi-)automatically by the
6904 <prgn>postinst</prgn> script.
6908 A common practice is to create a script called
6909 <file><var>package</var>-configure</file> and have the
6910 package's <prgn>postinst</prgn> call it if and only if the
6911 configuration file does not already exist. In certain
6912 cases it is useful for there to be an example or template
6913 file which the maintainer scripts use. Such files should
6914 be in <file>/usr/share/<var>package</var></file> or
6915 <file>/usr/lib/<var>package</var></file> (depending on whether
6916 they are architecture-independent or not). There should
6917 be symbolic links to them from
6918 <file>/usr/share/doc/<var>package</var>/examples</file> if
6919 they are examples, and should be perfectly ordinary
6920 <prgn>dpkg</prgn>-handled files (<em>not</em>
6921 configuration files).
6925 These two styles of configuration file handling must
6926 not be mixed, for that way lies madness:
6927 <prgn>dpkg</prgn> will ask about overwriting the file
6928 every time the package is upgraded.
6933 <heading>Sharing configuration files</heading>
6936 Packages which specify the same file as a
6937 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6938 with each other. (This is an instance of the general rule
6939 about not sharing files. Note that neither alternatives
6940 nor diversions are likely to be appropriate in this case;
6941 in particular, <prgn>dpkg</prgn> does not handle diverted
6942 <tt>conffile</tt>s well.)
6946 The maintainer scripts must not alter a <tt>conffile</tt>
6947 of <em>any</em> package, including the one the scripts
6952 If two or more packages use the same configuration file
6953 and it is reasonable for both to be installed at the same
6954 time, one of these packages must be defined as
6955 <em>owner</em> of the configuration file, i.e., it will be
6956 the package which handles that file as a configuration
6957 file. Other packages that use the configuration file must
6958 depend on the owning package if they require the
6959 configuration file to operate. If the other package will
6960 use the configuration file if present, but is capable of
6961 operating without it, no dependency need be declared.
6965 If it is desirable for two or more related packages to
6966 share a configuration file <em>and</em> for all of the
6967 related packages to be able to modify that configuration
6968 file, then the following should be done:
6969 <enumlist compact="compact">
6971 One of the related packages (the "owning" package)
6972 will manage the configuration file with maintainer
6973 scripts as described in the previous section.
6976 The owning package should also provide a program
6977 that the other packages may use to modify the
6981 The related packages must use the provided program
6982 to make any desired modifications to the
6983 configuration file. They should either depend on
6984 the core package to guarantee that the configuration
6985 modifier program is available or accept gracefully
6986 that they cannot modify the configuration file if it
6987 is not. (This is in addition to the fact that the
6988 configuration file may not even be present in the
6995 Sometimes it's appropriate to create a new package which
6996 provides the basic infrastructure for the other packages
6997 and which manages the shared configuration files. (The
6998 <tt>sgml-base</tt> package is a good example.)
7003 <heading>User configuration files ("dotfiles")</heading>
7006 The files in <file>/etc/skel</file> will automatically be
7007 copied into new user accounts by <prgn>adduser</prgn>.
7008 No other program should reference the files in
7009 <file>/etc/skel</file>.
7013 Therefore, if a program needs a dotfile to exist in
7014 advance in <file>$HOME</file> to work sensibly, that dotfile
7015 should be installed in <file>/etc/skel</file> and treated as a
7020 However, programs that require dotfiles in order to
7021 operate sensibly are a bad thing, unless they do create
7022 the dotfiles themselves automatically.
7026 Furthermore, programs should be configured by the Debian
7027 default installation to behave as closely to the upstream
7028 default behaviour as possible.
7032 Therefore, if a program in a Debian package needs to be
7033 configured in some way in order to operate sensibly, that
7034 should be done using a site-wide configuration file placed
7035 in <file>/etc</file>. Only if the program doesn't support a
7036 site-wide default configuration and the package maintainer
7037 doesn't have time to add it may a default per-user file be
7038 placed in <file>/etc/skel</file>.
7042 <file>/etc/skel</file> should be as empty as we can make it.
7043 This is particularly true because there is no easy (or
7044 necessarily desirable) mechanism for ensuring that the
7045 appropriate dotfiles are copied into the accounts of
7046 existing users when a package is installed.
7052 <heading>Log files</heading>
7054 Log files should usually be named
7055 <file>/var/log/<var>package</var>.log</file>. If you have many
7056 log files, or need a separate directory for permission
7057 reasons (<file>/var/log</file> is writable only by
7058 <file>root</file>), you should usually create a directory named
7059 <file>/var/log/<var>package</var></file> and place your log
7064 Log files must be rotated occasionally so that they don't
7065 grow indefinitely; the best way to do this is to drop a log
7066 rotation configuration file into the directory
7067 <file>/etc/logrotate.d</file> and use the facilities provided by
7068 logrotate.<footnote>
7070 The traditional approach to log files has been to set up
7071 <em>ad hoc</em> log rotation schemes using simple shell
7072 scripts and cron. While this approach is highly
7073 customizable, it requires quite a lot of sysadmin work.
7074 Even though the original Debian system helped a little
7075 by automatically installing a system which can be used
7076 as a template, this was deemed not enough.
7080 The use of <prgn>logrotate</prgn>, a program developed
7081 by Red Hat, is better, as it centralizes log management.
7082 It has both a configuration file
7083 (<file>/etc/logrotate.conf</file>) and a directory where
7084 packages can drop their individual log rotation
7085 configurations (<file>/etc/logrotate.d</file>).
7088 Here is a good example for a logrotate config
7089 file (for more information see <manref name="logrotate"
7091 <example compact="compact">
7092 /var/log/foo/*.log {
7097 /etc/init.d/foo force-reload
7101 This rotates all files under <file>/var/log/foo</file>, saves 12
7102 compressed generations, and forces the daemon to reload its
7103 configuration information after the log rotation.
7107 Log files should be removed when the package is
7108 purged (but not when it is only removed). This should be
7109 done by the <prgn>postrm</prgn> script when it is called
7110 with the argument <tt>purge</tt> (see <ref
7111 id="removedetails">).
7116 <heading>Permissions and owners</heading>
7119 The rules in this section are guidelines for general use.
7120 If necessary you may deviate from the details below.
7121 However, if you do so you must make sure that what is done
7122 is secure and you should try to be as consistent as possible
7123 with the rest of the system. You should probably also
7124 discuss it on <prgn>debian-devel</prgn> first.
7128 Files should be owned by <tt>root.root</tt>, and made
7129 writable only by the owner and universally readable (and
7130 executable, if appropriate), that is mode 644 or 755.
7134 Directories should be mode 755 or (for group-writability)
7135 mode 2775. The ownership of the directory should be
7136 consistent with its mode: if a directory is mode 2775, it
7137 should be owned by the group that needs write access to
7142 Setuid and setgid executables should be mode 4755 or 2755
7143 respectively, and owned by the appropriate user or group.
7144 They should not be made unreadable (modes like 4711 or
7145 2711 or even 4111); doing so achieves no extra security,
7146 because anyone can find the binary in the freely available
7147 Debian package; it is merely inconvenient. For the same
7148 reason you should not restrict read or execute permissions
7149 on non-set-id executables.
7153 Some setuid programs need to be restricted to particular
7154 sets of users, using file permissions. In this case they
7155 should be owned by the uid to which they are set-id, and by
7156 the group which should be allowed to execute them. They
7157 should have mode 4754; again there is no point in making
7158 them unreadable to those users who must not be allowed to
7163 It is possible to arrange that the system administrator can
7164 reconfigure the package to correspond to their local
7165 security policy by changing the permissions on a binary:
7166 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7167 described below.<footnote>
7168 Ordinary files installed by <prgn>dpkg</prgn> (as
7169 opposed to <tt>conffile</tt>s and other similar objects)
7170 normally have their permissions reset to the distributed
7171 permissions when the package is reinstalled. However,
7172 the use of <prgn>dpkg-statoverride</prgn> overrides this
7173 default behaviour. If you use this method, you should
7174 remember to describe <prgn>dpkg-statoverride</prgn> in
7175 the package documentation; being a relatively new
7176 addition to Debian, it is probably not yet well-known.
7178 Another method you should consider is to create a group for
7179 people allowed to use the program(s) and make any setuid
7180 executables executable only by that group.
7184 If you need to create a new user or group for your package
7185 there are two possibilities. Firstly, you may need to
7186 make some files in the binary package be owned by this
7187 user or group, or you may need to compile the user or
7188 group id (rather than just the name) into the binary
7189 (though this latter should be avoided if possible, as in
7190 this case you need a statically allocated id).</p>
7193 If you need a statically allocated id, you must ask for a
7194 user or group id from the <tt>base-passwd</tt> maintainer,
7195 and must not release the package until you have been
7196 allocated one. Once you have been allocated one you must
7197 either make the package depend on a version of the
7198 <tt>base-passwd</tt> package with the id present in
7199 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7200 your package to create the user or group itself with the
7201 correct id (using <tt>adduser</tt>) in its
7202 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7203 the <prgn>postinst</prgn> is to be preferred if it is
7204 possible, otherwise a pre-dependency will be needed on the
7205 <tt>adduser</tt> package.)
7209 On the other hand, the program might be able to determine
7210 the uid or gid from the user or group name at runtime, so
7211 that a dynamically allocated id can be used. In this case
7212 you should choose an appropriate user or group name,
7213 discussing this on <prgn>debian-devel</prgn> and checking
7214 with the <package/base-passwd/ maintainer that it is unique and that
7215 they do not wish you to use a statically allocated id
7216 instead. When this has been checked you must arrange for
7217 your package to create the user or group if necessary using
7218 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7219 <prgn>postinst</prgn> script (again, the latter is to be
7220 preferred if it is possible).
7224 Note that changing the numeric value of an id associated
7225 with a name is very difficult, and involves searching the
7226 file system for all appropriate files. You need to think
7227 carefully whether a static or dynamic id is required, since
7228 changing your mind later will cause problems.
7231 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7233 This section is not intended as policy, but as a
7234 description of the use of <prgn>dpkg-statoverride</prgn>.
7238 <prgn>dpkg-statoverride</prgn> is a replacement for the
7239 deprecated <tt>suidmanager</tt> package. Packages which
7240 previously used <tt>suidmanager</tt> should have a
7241 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7242 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7243 and <tt>suidunregister</tt> should now be simply removed
7244 from the maintainer scripts.
7248 If a system administrator wishes to have a file (or
7249 directory or other such thing) installed with owner and
7250 permissions different from those in the distributed Debian
7251 package, they can use the <prgn>dpkg-statoverride</prgn>
7252 program to instruct <prgn>dpkg</prgn> to use the different
7253 settings every time the file is installed. Thus the
7254 package maintainer should distribute the files with their
7255 normal permissions, and leave it for the system
7256 administrator to make any desired changes. For example, a
7257 daemon which is normally required to be setuid root, but
7258 in certain situations could be used without being setuid,
7259 should be installed setuid in the <tt>.deb</tt>. Then the
7260 local system administrator can change this if they wish.
7261 If there are two standard ways of doing it, the package
7262 maintainer can use <tt>debconf</tt> to find out the
7263 preference, and call <prgn>dpkg-statoverride</prgn> in the
7264 maintainer script if necessary to accommodate the system
7265 administrator's choice.
7269 Given the above, <prgn>dpkg-statoverride</prgn> is
7270 essentially a tool for system administrators and would not
7271 normally be needed in the maintainer scripts. There is
7272 one type of situation, though, where calls to
7273 <prgn>dpkg-statoverride</prgn> would be needed in the
7274 maintainer scripts, and that involves packages which use
7275 dynamically allocated user or group ids. In such a
7276 situation, something like the following idiom can be very
7277 helpful in the package's <prgn>postinst</prgn>, where
7278 <tt>sysuser</tt> is a dynamically allocated id:
7280 for i in /usr/bin/foo /usr/sbin/bar
7282 if ! dpkg-statoverride --list $i >/dev/null
7284 dpkg-statoverride --update --add sysuser root 4755 $i
7288 The corresponding <tt>dpkg-statoverride --remove</tt>
7289 calls can then be made unconditionally when the package is
7297 <chapt id="customized-programs">
7298 <heading>Customized programs</heading>
7300 <sect id="arch-spec">
7301 <heading>Architecture specification strings</heading>
7304 If a program needs to specify an <em>architecture specification
7305 string</em> in some place, the following format should be
7306 used: <var>arch</var>-<var>os</var><footnote>
7307 The following architectures and operating systems are
7308 currently recognised by <prgn>dpkg-architecture</prgn>.
7309 The architecture, <tt><var>arch</var></tt>, is one of
7310 the following: <tt>alpha</tt>, <tt>arm</tt>,
7311 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7312 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7313 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7314 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7315 operating system, <tt><var>os</var></tt>, is one of:
7316 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7317 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7318 reserved for the GNU/Hurd operating system.
7323 Note that we don't want to use
7324 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7325 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7326 since this would make our programs incompatible with other
7327 Linux distributions. We also don't use something like
7328 <tt><var>arch</var>-unknown-linux</tt>, since the
7329 <tt>unknown</tt> does not look very good.
7334 <heading>Daemons</heading>
7337 The configuration files <file>/etc/services</file>,
7338 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7339 by the <prgn>netbase</prgn> package and must not be modified
7344 If a package requires a new entry in one of these files, the
7345 maintainer should get in contact with the
7346 <prgn>netbase</prgn> maintainer, who will add the entries
7347 and release a new version of the <prgn>netbase</prgn>
7352 The configuration file <file>/etc/inetd.conf</file> must not be
7353 modified by the package's scripts except via the
7354 <prgn>update-inetd</prgn> script or the
7355 <file>DebianNet.pm</file> Perl module. See their documentation
7356 for details on how to add entries.
7360 If a package wants to install an example entry into
7361 <file>/etc/inetd.conf</file>, the entry must be preceded with
7362 exactly one hash character (<tt>#</tt>). Such lines are
7363 treated as "commented out by user" by the
7364 <prgn>update-inetd</prgn> script and are not changed or
7365 activated during package updates.
7370 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7374 Some programs need to create pseudo-ttys. This should be done
7375 using Unix98 ptys if the C library supports it. The resulting
7376 program must not be installed setuid root, unless that
7377 is required for other functionality.
7381 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7382 <file>/var/log/lastlog</file> must be installed writeable by
7383 group <tt>utmp</tt>. Programs which need to modify those
7384 files must be installed setgid <tt>utmp</tt>.
7389 <heading>Editors and pagers</heading>
7392 Some programs have the ability to launch an editor or pager
7393 program to edit or display a text document. Since there are
7394 lots of different editors and pagers available in the Debian
7395 distribution, the system administrator and each user should
7396 have the possibility to choose their preferred editor and
7401 In addition, every program should choose a good default
7402 editor/pager if none is selected by the user or system
7407 Thus, every program that launches an editor or pager must
7408 use the EDITOR or PAGER environment variable to determine
7409 the editor or pager the user wishes to use. If these
7410 variables are not set, the programs <file>/usr/bin/editor</file>
7411 and <file>/usr/bin/pager</file> should be used, respectively.
7415 These two files are managed through the <prgn>dpkg</prgn>
7416 "alternatives" mechanism. Thus every package providing an
7417 editor or pager must call the
7418 <prgn>update-alternatives</prgn> script to register these
7423 If it is very hard to adapt a program to make use of the
7424 EDITOR or PAGER variables, that program may be configured to
7425 use <file>/usr/bin/sensible-editor</file> and
7426 <file>/usr/bin/sensible-pager</file> as the editor or pager
7427 program respectively. These are two scripts provided in the
7428 Debian base system that check the EDITOR and PAGER variables
7429 and launch the appropriate program, and fall back to
7430 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7431 variable is not set.
7435 A program may also use the VISUAL environment variable to
7436 determine the user's choice of editor. If it exists, it
7437 should take precedence over EDITOR. This is in fact what
7438 <file>/usr/bin/sensible-editor</file> does.
7442 It is not required for a package to depend on
7443 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7444 package to provide such virtual packages.<footnote>
7445 The Debian base system already provides an editor and a
7451 <sect id="web-appl">
7452 <heading>Web servers and applications</heading>
7455 This section describes the locations and URLs that should
7456 be used by all web servers and web applications in the
7463 Cgi-bin executable files are installed in the
7465 <example compact="compact">
7466 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7468 and should be referred to as
7469 <example compact="compact">
7470 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7475 <p>Access to HTML documents</p>
7478 HTML documents for a package are stored in
7479 <file>/usr/share/doc/<var>package</var></file>
7480 and can be referred to as
7481 <example compact="compact">
7482 http://localhost/doc/<var>package</var>/<var>filename</var>
7487 The web server should restrict access to the document
7488 tree so that only clients on the same host can read
7489 the documents. If the web server does not support such
7490 access controls, then it should not provide access at
7491 all, or ask about providing access during installation.
7496 <p>Web Document Root</p>
7499 Web Applications should try to avoid storing files in
7500 the Web Document Root. Instead they should use the
7501 /usr/share/doc/<var>package</var> directory for
7502 documents and register the Web Application via the
7503 <package>doc-base</package> package. If access to the
7504 web document root is unavoidable then use
7505 <example compact="compact">
7508 as the Document Root. This might be just a symbolic
7509 link to the location where the system administrator
7510 has put the real document root.
7518 <sect id="mail-transport-agents">
7519 <heading>Mail transport, delivery and user agents</heading>
7522 Debian packages which process electronic mail, whether mail
7523 user agents (MUAs) or mail transport agents (MTAs), must
7524 ensure that they are compatible with the configuration
7525 decisions below. Failure to do this may result in lost
7526 mail, broken <tt>From:</tt> lines, and other serious brain
7531 The mail spool is <file>/var/mail</file> and the interface to
7532 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7533 the FHS). On older systems, the mail spool may be
7534 physically located in <file>/var/spool/mail</file>, but all
7535 access to the mail spool should be via the
7536 <file>/var/mail</file> symlink. The mail spool is part of the
7537 base system and not part of the MTA package.
7541 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7542 programs (such as IMAP daemons) must lock the mailbox in an
7543 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7544 be combined with dot locking. To avoid deadlocks, a program
7545 should use <tt>fcntl()</tt> first and dot locking after
7546 this, or alternatively implement the two locking methods in
7547 a non blocking way<footnote>
7548 If it is not possible to establish both locks, the
7549 system shouldn't wait for the second lock to be
7550 established, but remove the first lock, wait a (random)
7551 time, and start over locking again.
7552 </footnote>. Using the functions <tt>maillock</tt> and
7553 <tt>mailunlock</tt> provided by the
7554 <tt>liblockfile*</tt><footnote>
7555 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7556 to use these functions.
7557 </footnote> packages is the recommended way to realize this.
7561 Mailboxes are generally mode 660
7562 <tt><var>user</var>.mail</tt> unless the system
7563 administrator has chosen otherwise. A MUA may remove a
7564 mailbox (unless it has nonstandard permissions) in which
7565 case the MTA or another MUA must recreate it if needed.
7566 Mailboxes must be writable by group mail.
7570 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7571 be setgid mail to do the locking mentioned above (and
7572 must obviously avoid accessing other users' mailboxes
7573 using this privilege).</p>
7576 <file>/etc/aliases</file> is the source file for the system mail
7577 aliases (e.g., postmaster, usenet, etc.), it is the one
7578 which the sysadmin and <prgn>postinst</prgn> scripts may
7579 edit. After <file>/etc/aliases</file> is edited the program or
7580 human editing it must call <prgn>newaliases</prgn>. All MTA
7581 packages must come with a <prgn>newaliases</prgn> program,
7582 even if it does nothing, but older MTA packages did not do
7583 this so programs should not fail if <prgn>newaliases</prgn>
7584 cannot be found. Note that because of this, all MTA
7585 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7586 <tt>Replaces: mail-transport-agent</tt> control file
7591 The convention of writing <tt>forward to
7592 <var>address</var></tt> in the mailbox itself is not
7593 supported. Use a <tt>.forward</tt> file instead.</p>
7596 The <prgn>rmail</prgn> program used by UUCP
7597 for incoming mail should be <file>/usr/sbin/rmail</file>.
7598 Likewise, <prgn>rsmtp</prgn>, for receiving
7599 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7603 If your package needs to know what hostname to use on (for
7604 example) outgoing news and mail messages which are generated
7605 locally, you should use the file <file>/etc/mailname</file>. It
7606 will contain the portion after the username and <tt>@</tt>
7607 (at) sign for email addresses of users on the machine
7608 (followed by a newline).
7612 Such package should check for the existence of this file
7613 when it is being configured. If it exists, it should be
7614 used without comment, although an MTA's configuration script
7615 may wish to prompt the user even if it finds that this file
7616 exists. If the file does not exist, the package should
7617 prompt the user for the value (preferably using
7618 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7619 as well as using it in the package's configuration. The
7620 prompt should make it clear that the name will not just be
7621 used by that package. For example, in this situation the
7622 <tt>inn</tt> package could say something like:
7623 <example compact="compact">
7624 Please enter the "mail name" of your system. This is the
7625 hostname portion of the address to be shown on outgoing
7626 news and mail messages. The default is
7627 <var>syshostname</var>, your system's host name. Mail
7628 name ["<var>syshostname</var>"]:
7630 where <var>syshostname</var> is the output of <tt>hostname
7636 <heading>News system configuration</heading>
7639 All the configuration files related to the NNTP (news)
7640 servers and clients should be located under
7641 <file>/etc/news</file>.</p>
7644 There are some configuration issues that apply to a number
7645 of news clients and server packages on the machine. These
7649 <tag><file>/etc/news/organization</file></tag>
7651 A string which should appear as the
7652 organization header for all messages posted
7653 by NNTP clients on the machine
7656 <tag><file>/etc/news/server</file></tag>
7658 Contains the FQDN of the upstream NNTP
7659 server, or localhost if the local machine is
7664 Other global files may be added as required for cross-package news
7671 <heading>Programs for the X Window System</heading>
7674 <heading>Providing X support and package priorities</heading>
7677 Programs that can be configured with support for the X
7678 Window System must be configured to do so and must declare
7679 any package dependencies necessary to satisfy their
7680 runtime requirements when using the X Window System. If
7681 such a package is of higher priority than the X packages
7682 on which it depends, it is required that either the
7683 X-specific components be split into a separate package, or
7684 that an alternative version of the package, which includes
7685 X support, be provided, or that the package's priority be
7691 <heading>Packages providing an X server</heading>
7694 Packages that provide an X server that, directly or
7695 indirectly, communicates with real input and display
7696 hardware should declare in their control data that they
7697 provide the virtual package <tt>xserver</tt>.<footnote>
7698 This implements current practice, and provides an
7699 actual policy for usage of the <tt>xserver</tt>
7700 virtual package which appears in the virtual packages
7701 list. In a nutshell, X servers that interface
7702 directly with the display and input hardware or via
7703 another subsystem (e.g., GGI) should provide
7704 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7705 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7711 <heading>Packages providing a terminal emulator</heading>
7714 Packages that provide a terminal emulator for the X Window
7715 System which meet the criteria listed below should declare
7716 in their control data that they provide the virtual
7717 package <tt>x-terminal-emulator</tt>. They should also
7718 register themselves as an alternative for
7719 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7724 To be an <tt>x-terminal-emulator</tt>, a program must:
7725 <list compact="compact">
7727 Be able to emulate a DEC VT100 terminal, or a
7728 compatible terminal.
7732 Support the command-line option <tt>-e
7733 <var>command</var></tt>, which creates a new
7734 terminal window<footnote>
7735 "New terminal window" does not necessarily mean
7736 a new top-level X window directly parented by
7737 the window manager; it could, if the terminal
7738 emulator application were so coded, be a new
7739 "view" in a multiple-document interface (MDI).
7741 and runs the specified <var>command</var>,
7742 interpreting the entirity of the rest of the command
7743 line as a command to pass straight to exec, in the
7744 manner that <tt>xterm</tt> does.
7748 Support the command-line option <tt>-T
7749 <var>title</var></tt>, which creates a new terminal
7750 window with the window title <var>title</var>.
7757 <heading>Packages providing a window manager</heading>
7760 Packages that provide a window manager should declare in
7761 their control data that they provide the virtual package
7762 <tt>x-window-manager</tt>. They should also register
7763 themselves as an alternative for
7764 <file>/usr/bin/x-window-manager</file>, with a priority
7765 calculated as follows:
7766 <list compact="compact">
7768 Start with a priority of 20.
7772 If the window manager supports the Debian menu
7773 system, add 20 points if this support is available
7774 in the package's default configuration (i.e., no
7775 configuration files belonging to the system or user
7776 have to be edited to activate the feature); if
7777 configuration files must be modified, add only 10
7783 If the window manager complies with <url
7784 id="http://www.freedesktop.org/Standards/wm-spec"
7785 name="The Window Manager Specification Project">,
7786 written by the <url id="http://www.freedesktop.org/"
7787 name="Free Desktop Group">, add 40 points.
7791 If the window manager permits the X session to be
7792 restarted using a <em>different</em> window manager
7793 (without killing the X server) in its default
7794 configuration, add 10 points; otherwise add none.
7801 <heading>Packages providing fonts</heading>
7804 Packages that provide fonts for the X Window
7806 For the purposes of Debian Policy, a "font for the X
7807 Window System" is one which is accessed via X protocol
7808 requests. Fonts for the Linux console, for PostScript
7809 renderers, or any other purpose, do not fit this
7810 definition. Any tool which makes such fonts available
7811 to the X Window System, however, must abide by this
7814 must do a number of things to ensure that they are both
7815 available without modification of the X or font server
7816 configuration, and that they do not corrupt files used by
7817 other font packages to register information about
7821 Fonts of any type supported by the X Window System
7822 must be in a separate binary package from any
7823 executables, libraries, or documentation (except
7824 that specific to the fonts shipped, such as their
7825 license information). If one or more of the fonts
7826 so packaged are necessary for proper operation of
7827 the package with which they are associated the font
7828 package may be Recommended; if the fonts merely
7829 provide an enhancement, a Suggests relationship may
7830 be used. Packages must not Depend on font
7832 This is because the X server may retrieve fonts
7833 from the local filesystem or over the network
7834 from an X font server; the Debian package system
7835 is empowered to deal only with the local
7841 BDF fonts must be converted to PCF fonts with the
7842 <prgn>bdftopcf</prgn> utility (available in the
7843 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7844 placed in a directory that corresponds to their
7846 <list compact="compact">
7848 100 dpi fonts must be placed in
7849 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7853 75 dpi fonts must be placed in
7854 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7858 Character-cell fonts, cursor fonts, and other
7859 low-resolution fonts must be placed in
7860 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7866 Speedo fonts must be placed in
7867 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7871 Type 1 fonts must be placed in
7872 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7873 metric files are available, they must be placed here
7878 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7879 other than those listed above must be neither
7880 created nor used. (The <file>PEX</file>, <file>CID</file>,
7881 and <file>cyrillic</file> directories are excepted for
7882 historical reasons, but installation of files into
7883 these directories remains discouraged.)
7887 Font packages may, instead of placing files directly
7888 in the X font directories listed above, provide
7889 symbolic links in that font directory pointing to
7890 the files' actual location in the filesystem. Such
7891 a location must comply with the FHS.
7895 Font packages should not contain both 75dpi and
7896 100dpi versions of a font. If both are available,
7897 they should be provided in separate binary packages
7898 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7899 the names of the packages containing the
7900 corresponding fonts.
7904 Fonts destined for the <file>misc</file> subdirectory
7905 should not be included in the same package as 75dpi
7906 or 100dpi fonts; instead, they should be provided in
7907 a separate package with <tt>-misc</tt> appended to
7912 Font packages must not provide the files
7913 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7914 <file>fonts.scale</file> in a font directory:
7917 <file>fonts.dir</file> files must not be provided at all.
7921 <file>fonts.alias</file> and <file>fonts.scale</file>
7922 files, if needed, should be provided in the
7924 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7925 where <var>fontdir</var> is the name of the
7927 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7928 package's corresponding fonts are stored
7929 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7930 <var>package</var> is the name of the package
7931 that provides these fonts, and
7932 <var>extension</var> is either <tt>scale</tt>
7933 or <tt>alias</tt>, whichever corresponds to
7940 Font packages must declare a dependency on
7941 <tt>xutils (>> 4.0.3)</tt> in their control
7946 Font packages that provide one or more
7947 <file>fonts.scale</file> files as described above must
7948 invoke <prgn>update-fonts-scale</prgn> on each
7949 directory into which they installed fonts
7950 <em>before</em> invoking
7951 <prgn>update-fonts-dir</prgn> on that directory.
7952 This invocation must occur in both the
7953 <prgn>postinst</prgn> (for all arguments) and
7954 <prgn>postrm</prgn> (for all arguments except
7955 <tt>upgrade</tt>) scripts.
7959 Font packages that provide one or more
7960 <file>fonts.alias</file> files as described above must
7961 invoke <prgn>update-fonts-alias</prgn> on each
7962 directory into which they installed fonts. This
7963 invocation must occur in both the
7964 <prgn>postinst</prgn> (for all arguments) and
7965 <prgn>postrm</prgn> (for all arguments except
7966 <tt>upgrade</tt>) scripts.
7970 Font packages must invoke
7971 <prgn>update-fonts-dir</prgn> on each directory into
7972 which they installed fonts. This invocation must
7973 occur in both the <prgn>postinst</prgn> (for all
7974 arguments) and <prgn>postrm</prgn> (for all
7975 arguments except <tt>upgrade</tt>) scripts.
7979 Font packages must not provide alias names for the
7980 fonts they include which collide with alias names
7981 already in use by fonts already packaged.
7985 Font packages must not provide fonts with the same
7986 XLFD registry name as another font already packaged.
7993 <heading>Application defaults files</heading>
7996 Application defaults files must be installed in the
7997 directory <file>/etc/X11/app-defaults/</file> (use of a
7998 localized subdirectory of <file>/etc/X11/</file> as described
7999 in the <em>X Toolkit Intrinsics - C Language
8000 Interface</em> manual is also permitted). They must be
8001 registered as <tt>conffile</tt>s or handled as
8002 configuration files. Packages must not provide the
8003 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
8007 Customization of programs' X resources may also be
8008 supported with the provision of a file with the same name
8009 as that of the package placed in the
8010 <file>/etc/X11/Xresources/</file> directory, which must
8011 registered as a <tt>conffile</tt> or handled as a
8012 configuration file.<footnote>
8013 Note that this mechanism is not the same as using
8014 app-defaults; app-defaults are tied to the client
8015 binary on the local filesystem, whereas X resources
8016 are stored in the X server and affect all connecting
8019 <em>Important:</em> packages that install files into the
8020 <file>/etc/X11/Xresources/</file> directory must conflict with
8021 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
8022 it is possible for the installing package to destroy a
8023 previously-existing <file>/etc/X11/Xresources</file> file
8024 which had been customized by the system administrator.
8029 <heading>Installation directory issues</heading>
8032 Packages using the X Window System should not be
8033 configured to install files under the <file>/usr/X11R6/</file>
8034 directory unless they use <prgn>imake</prgn>. The
8035 <file>/usr/X11R6/</file> directory hierarchy should be
8036 regarded as deprecated for all packages except the X
8037 Window System itself, and those which use the
8038 <prgn>imake</prgn> program it provides, in which case the
8039 packages may transition out of the <file>/usr/X11R6/</file>
8040 directory at the maintainer's discretion.<footnote>
8041 <prgn>Imake</prgn>-using programs are exempt because,
8042 as long as they are written correctly, the pathnames
8043 they use to locate resources and install themselves
8044 are derived wholly from the X Window System
8045 configuration. Thus, in the event that the X Window
8046 System moves to <file>/usr/X11R7/</file>,
8047 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
8048 that is required for these programs is a recompile
8049 against the corresponding X Window System library
8050 development packages.
8055 Programs that use GNU <prgn>autoconf</prgn> and
8056 <prgn>automake</prgn> are usually easily configured at
8057 compile time to use <file>/usr/</file> instead of
8058 <file>/usr/X11R6/</file>, and this should be done whenever
8059 possible. Configuration files for window managers and
8060 display managers should be placed in a subdirectory of
8061 <file>/etc/X11/</file> corresponding to the package name due
8062 to these programs' tight integration with the mechanisms
8063 of the X Window System. Application-level programs should
8064 use the <file>/etc/</file> directory unless otherwise mandated
8069 The installation of files into subdirectories
8070 of <file>/usr/X11R6/include/X11/</file> and
8071 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8072 package maintainers should determine if subdirectories of
8073 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8074 instead. (The use of symbolic links from the
8075 <file>X11R6</file> directories to other FHS-compliant
8076 locations is encouraged if the program is not easily
8077 configured to look elsewhere for its files.)
8081 Packages must not provide or install files into the directories
8082 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8083 <file>/usr/lib/X11/</file>. Files within a package should,
8084 however, make reference to these directories, rather than
8085 their <tt>X11R6</tt>-named counterparts
8086 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8087 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8088 referred to have not been moved to other FHS-compliant
8094 <heading>The OSF/Motif and OpenMotif libraries</heading>
8097 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8098 OpenMotif libraries</em><footnote>
8099 OSF/Motif and OpenMotif are collectively referred to as
8100 "Motif" in this policy document.
8102 should be compiled against and tested with LessTif (a free
8103 re-implementation of Motif) instead. If the maintainer
8104 judges that the program or programs do not work
8105 sufficiently well with LessTif to be distributed and
8106 supported, but do so when compiled against Motif, then two
8107 versions of the package should be created; one linked
8108 statically against Motif and with <tt>-smotif</tt>
8109 appended to the package name, and one linked dynamically
8110 against Motif and with <tt>-dmotif</tt> appended to the
8115 Both Motif-linked versions are dependent
8116 upon non-DFSG-compliant software and thus cannot be
8117 uploaded to the <em>main</em> distribution; if the
8118 software is itself DFSG-compliant it may be uploaded to
8119 the <em>contrib</em> distribution. While known existing
8120 versions of Motif permit unlimited redistribution of
8121 binaries linked against the library (whether statically or
8122 dynamically), it is the package maintainer's
8123 responsibility to determine whether this is permitted by
8124 the license of the copy of Motif in their possession.
8130 <heading>Perl programs and modules</heading>
8133 Perl programs and modules should follow the current Perl policy.
8137 The Perl policy can be found in the <tt>perl-policy</tt>
8138 files in the <tt>debian-policy</tt> package.
8139 It is also available from the Debian web mirrors at
8140 <tt><url name="/doc/packaging-manuals/perl-policy/"
8141 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8146 <heading>Emacs lisp programs</heading>
8149 Please refer to the "Debian Emacs Policy" for details of how to
8150 package emacs lisp programs.
8154 The Emacs policy is available in
8155 <file>debian-emacs-policy.gz</file> of the
8156 <package>emacsen-common</package> package.
8157 It is also available from the Debian web mirrors at
8158 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8159 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8164 <heading>Games</heading>
8167 The permissions on <file>/var/games</file> are mode 755, owner
8168 <tt>root</tt> and group <tt>root</tt>.
8172 Each game decides on its own security policy.</p>
8175 Games which require protected, privileged access to
8176 high-score files, savegames, etc., may be made
8177 set-<em>group</em>-id (mode 2755) and owned by
8178 <tt>root.games</tt>, and use files and directories with
8179 appropriate permissions (770 <tt>root.games</tt>, for
8180 example). They must not be made
8181 set-<em>user</em>-id, as this causes security problems. (If
8182 an attacker can subvert any set-user-id game they can
8183 overwrite the executable of any other, causing other players
8184 of these games to run a Trojan horse program. With a
8185 set-group-id game the attacker only gets access to less
8186 important game data, and if they can get at the other
8187 players' accounts at all it will take considerably more
8191 Some packages, for example some fortune cookie programs, are
8192 configured by the upstream authors to install with their
8193 data files or other static information made unreadable so
8194 that they can only be accessed through set-id programs
8195 provided. You should not do this in a Debian package: anyone can
8196 download the <file>.deb</file> file and read the data from it,
8197 so there is no point making the files unreadable. Not
8198 making the files unreadable also means that you don't have
8199 to make so many programs set-id, which reduces the risk of a
8203 As described in the FHS, binaries of games should be
8204 installed in the directory <file>/usr/games</file>. This also
8205 applies to games that use the X Window System. Manual pages
8206 for games (X and non-X games) should be installed in
8207 <file>/usr/share/man/man6</file>.</p>
8213 <heading>Documentation</heading>
8216 <heading>Manual pages</heading>
8219 You should install manual pages in <prgn>nroff</prgn> source
8220 form, in appropriate places under <file>/usr/share/man</file>.
8221 You should only use sections 1 to 9 (see the FHS for more
8222 details). You must not install a preformatted "cat page".
8226 Each program, utility, and function should have an
8227 associated manual page included in the same package. It is
8228 suggested that all configuration files also have a manual
8229 page included as well. Manual pages for protocols and other
8230 auxiliary things are optional.
8234 If no manual page is available, this is considered as a bug
8235 and should be reported to the Debian Bug Tracking System (the
8236 maintainer of the package is allowed to write this bug report
8237 themselves, if they so desire). Do not close the bug report
8238 until a proper man page is available.<footnote>
8239 It is not very hard to write a man page. See the
8240 <url id="http://www.schweikhardt.net/man_page_howto.html"
8241 name="Man-Page-HOWTO">,
8242 <manref name="man" section="7">, the examples
8243 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8244 the helper programs <prgn>help2man</prgn>, or the
8245 directory <file>/usr/share/doc/man-db/examples</file>.
8250 You may forward a complaint about a missing man page to the
8251 upstream authors, and mark the bug as forwarded in the
8252 Debian bug tracking system. Even though the GNU Project do
8253 not in general consider the lack of a man page to be a bug,
8254 we do; if they tell you that they don't consider it a bug
8255 you should leave the bug in our bug tracking system open
8260 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8264 If one man page needs to be accessible via several names it
8265 is better to use a symbolic link than the <file>.so</file>
8266 feature, but there is no need to fiddle with the relevant
8267 parts of the upstream source to change from <file>.so</file> to
8268 symlinks: don't do it unless it's easy. You should not
8269 create hard links in the manual page directories, nor put
8270 absolute filenames in <file>.so</file> directives. The filename
8271 in a <file>.so</file> in a man page should be relative to the
8272 base of the man page tree (usually
8273 <file>/usr/share/man</file>). If you do not create any links
8274 (whether symlinks, hard links, or <tt>.so</tt> directives)
8275 in the filesystem to the alternate names of the man page,
8276 then you should not rely on <prgn>man</prgn> finding your
8277 man page under those names based solely on the information in
8278 the man page's header.<footnote>
8279 Supporting this in <prgn>man</prgn> often requires
8280 unreasonable processing time to find a manual page or to
8281 report that none exists, and moves knowledge into man's
8282 database that would be better left in the filesystem.
8283 This support is therefore deprecated and will cease to
8284 be present in the future.
8290 <heading>Info documents</heading>
8293 Info documents should be installed in <file>/usr/share/info</file>.
8294 They should be compressed with <tt>gzip -9</tt>.
8298 Your package should call <prgn>install-info</prgn> to update
8299 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8300 script when called with a <tt>configure</tt> argument, for
8302 <example compact="compact">
8303 install-info --quiet --section Development Development \
8304 /usr/share/info/foobar.info
8308 It is a good idea to specify a section for the location of
8309 your program; this is done with the <tt>--section</tt>
8310 switch. To determine which section to use, you should look
8311 at <file>/usr/share/info/dir</file> on your system and choose the most
8312 relevant (or create a new section if none of the current
8313 sections are relevant). Note that the <tt>--section</tt>
8314 flag takes two arguments; the first is a regular expression
8315 to match (case-insensitively) against an existing section,
8316 the second is used when creating a new one.</p>
8319 You should remove the entries in the <prgn>prerm</prgn>
8320 script when called with a <tt>remove</tt> argument:
8321 <example compact="compact">
8322 install-info --quiet --remove /usr/share/info/foobar.info
8326 If <prgn>install-info</prgn> cannot find a description entry
8327 in the Info file you must supply one. See <manref
8328 name="install-info" section="8"> for details.</p>
8332 <heading>Additional documentation</heading>
8335 Any additional documentation that comes with the package may
8336 be installed at the discretion of the package maintainer.
8337 Text documentation should be installed in the directory
8338 <file>/usr/share/doc/<var>package</var></file>, where
8339 <var>package</var> is the name of the package, and
8340 compressed with <tt>gzip -9</tt> unless it is small.
8344 If a package comes with large amounts of documentation which
8345 many users of the package will not require you should create
8346 a separate binary package to contain it, so that it does not
8347 take up disk space on the machines of users who do not need
8348 or want it installed.</p>
8351 It is often a good idea to put text information files
8352 (<file>README</file>s, changelogs, and so forth) that come with
8353 the source package in <file>/usr/share/doc/<var>package</var></file>
8354 in the binary package. However, you don't need to install
8355 the instructions for building and installing the package, of
8359 Packages must not require the existence of any files in
8360 <file>/usr/share/doc/</file> in order to function
8362 The system administrator should be able to
8363 delete files in <file>/usr/share/doc/</file> without causing
8364 any programs to break.
8366 Any files that are referenced by programs but are also
8367 useful as standalone documentation should be installed under
8368 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8369 <file>/usr/share/doc/<var>package</var></file>.
8373 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8374 link to another directory in <file>/usr/share/doc</file> only if
8375 the two packages both come from the same source and the
8376 first package Depends on the second.<footnote>
8378 Please note that this does not override the section on
8379 changelog files below, so the file
8380 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8381 must refer to the changelog for the current version of
8382 <var>package</var> in question. In practice, this means
8383 that the sources of the target and the destnation of the
8384 symlink must be the same (same source package and
8391 Former Debian releases placed all additional documentation
8392 in <file>/usr/doc/<var>package</var></file>. This has been
8393 changed to <file>/usr/share/doc/<var>package</var></file>,
8394 and packages must not put documentation in the directory
8395 <file>/usr/doc/<var>package</var></file>. <footnote>
8396 At this phase of the transition, we no longer require a
8397 symbolic link in <file>/usr/doc/</file>. At a later point,
8398 policy shall change to make the symbolic links a bug.
8404 <heading>Preferred documentation formats</heading>
8407 The unification of Debian documentation is being carried out
8411 If your package comes with extensive documentation in a
8412 markup format that can be converted to various other formats
8413 you should if possible ship HTML versions in a binary
8414 package, in the directory
8415 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8416 its subdirectories.<footnote>
8417 The rationale: The important thing here is that HTML
8418 docs should be available in <em>some</em> package, not
8419 necessarily in the main binary package.
8424 Other formats such as PostScript may be provided at the
8425 package maintainer's discretion.
8429 <sect id="copyrightfile">
8430 <heading>Copyright information</heading>
8433 Every package must be accompanied by a verbatim copy of its
8434 copyright and distribution license in the file
8435 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8436 file must neither be compressed nor be a symbolic link.
8440 In addition, the copyright file must say where the upstream
8441 sources (if any) were obtained. It should name the original
8442 authors of the package and the Debian maintainer(s) who were
8443 involved with its creation.</p>
8446 A copy of the file which will be installed in
8447 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8448 be in <file>debian/copyright</file> in the source package.
8452 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8453 link to another directory in <file>/usr/share/doc</file> only if
8454 the two packages both come from the same source and the
8455 first package Depends on the second. These rules are
8456 important because copyrights must be extractable by
8461 Packages distributed under the UCB BSD license, the Artistic
8462 license, the GNU GPL, and the GNU LGPL should refer to the
8463 files <file>/usr/share/common-licenses/BSD</file>,
8464 <file>/usr/share/common-licenses/Artistic</file>,
8465 <file>/usr/share/common-licenses/GPL</file>, and
8466 <file>/usr/share/common-licenses/LGPL</file> respectively,
8467 rather than quoting them in the copyright file.
8471 You should not use the copyright file as a general <file>README</file>
8472 file. If your package has such a file it should be
8473 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8474 <file>README.Debian</file> or some other appropriate place.</p>
8478 <heading>Examples</heading>
8481 Any examples (configurations, source files, whatever),
8482 should be installed in a directory
8483 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8484 files should not be referenced by any program: they're there
8485 for the benefit of the system administrator and users as
8486 documentation only. Architecture-specific example files
8487 should be installed in a directory
8488 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8490 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8491 latter directory itself may be a symbolic link to the
8496 If the purpose of a package is to provide examples, then the
8497 example files may be installed into
8498 <file>/usr/share/doc/<var>package</var></file>.
8502 <sect id="changelogs">
8503 <heading>Changelog files</heading>
8506 Packages that are not Debian-native must contain a
8507 compressed copy of the <file>debian/changelog</file> file from
8508 the Debian source tree in
8509 <file>/usr/share/doc/<var>package</var></file> with the name
8510 <file>changelog.Debian.gz</file>.
8514 If an upstream changelog is available, it should be accessible as
8515 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8516 plain text. If the upstream changelog is distributed in
8517 HTML, it should be made available in that form as
8518 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8519 and a plain text <file>changelog.gz</file> should be generated
8520 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8521 the upstream changelog files do not already conform to this
8522 naming convention, then this may be achieved either by
8523 renaming the files, or by adding a symbolic link, at the
8524 maintainer's discretion.<footnote>
8525 Rationale: People should not have to look in places for
8526 upstream changelogs merely because they are given
8527 different names or are distributed in HTML format.
8532 All of these files should be installed compressed using
8533 <tt>gzip -9</tt>, as they will become large with time even
8534 if they start out small.
8538 If the package has only one changelog which is used both as
8539 the Debian changelog and the upstream one because there is
8540 no separate upstream maintainer then that changelog should
8541 usually be installed as
8542 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8543 there is a separate upstream maintainer, but no upstream
8544 changelog, then the Debian changelog should still be called
8545 <file>changelog.Debian.gz</file>.
8549 For details about the format and contents of the Debian
8550 changelog file, please see <ref id="dpkgchangelog">.
8555 <appendix id="pkg-scope">
8556 <heading>Introduction and scope of these appendices</heading>
8559 These appendices are taken essentially verbatim from the
8560 now-deprecated Packaging Manual, version 3.2.1.0. They are
8561 the chapters which are likely to be of use to package
8562 maintainers and which have not already been included in the
8563 policy document itself. Most of these sections are very likely
8564 not relevant to policy; they should be treated as
8565 documentation for the packaging system. Please note that these
8566 appendices are included for convenience, and for historical
8567 reasons: they used to be part of policy package, and they have
8568 not yet been incorporated into dpkg documentation. However,
8569 they still have value, and hence they are presented here.
8573 They have not yet been checked to ensure that they are
8574 compatible with the contents of policy, and if there are any
8575 contradictions, the version in the main policy document takes
8576 precedence. The remaining chapters of the old Packaging
8577 Manual have also not been read in detail to ensure that there
8578 are not parts which have been left out. Both of these will be
8583 Certain parts of the Packaging manual were integrated into the
8584 Policy Manual proper, and removed from the appendices. Links
8585 have been placed from the old locations to the new ones.
8589 <prgn>dpkg</prgn> is a suite of programs for creating binary
8590 package files and installing and removing them on Unix
8592 <prgn>dpkg</prgn> is targetted primarily at Debian
8593 GNU/Linux, but may work on or be ported to other
8599 The binary packages are designed for the management of
8600 installed executable programs (usually compiled binaries) and
8601 their associated data, though source code examples and
8602 documentation are provided as part of some packages.</p>
8605 This manual describes the technical aspects of creating Debian
8606 binary packages (<file>.deb</file> files). It documents the
8607 behaviour of the package management programs
8608 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8609 they interact with packages.</p>
8612 It also documents the interaction between
8613 <prgn>dselect</prgn>'s core and the access method scripts it
8614 uses to actually install the selected packages, and describes
8615 how to create a new access method.</p>
8618 This manual does not go into detail about the options and
8619 usage of the package building and installation tools. It
8620 should therefore be read in conjuction with those programs'
8625 The utility programs which are provided with <prgn>dpkg</prgn>
8626 for managing various system configuration and similar issues,
8627 such as <prgn>update-rc.d</prgn> and
8628 <prgn>install-info</prgn>, are not described in detail here -
8629 please see their man pages.
8633 It is assumed that the reader is reasonably familiar with the
8634 <prgn>dpkg</prgn> System Administrators' manual.
8635 Unfortunately this manual does not yet exist.
8639 The Debian version of the FSF's GNU hello program is provided
8640 as an example for people wishing to create Debian
8641 packages. The Debian <prgn>debmake</prgn> package is
8642 recommended as a very helpful tool in creating and maintaining
8643 Debian packages. However, while the tools and examples are
8644 helpful, they do not replace the need to read and follow the
8645 Policy and Programmer's Manual.</p>
8648 <appendix id="pkg-binarypkg">
8649 <heading>Binary packages (from old Packaging Manual)</heading>
8652 The binary package has two main sections. The first part
8653 consists of various control information files and scripts used
8654 by <prgn>dpkg</prgn> when installing and removing. See <ref
8655 id="pkg-controlarea">.
8659 The second part is an archive containing the files and
8660 directories to be installed.
8664 In the future binary packages may also contain other
8665 components, such as checksums and digital signatures. The
8666 format for the archive is described in full in the
8667 <file>deb(5)</file> man page.
8671 <sect id="pkg-bincreating"><heading>Creating package files -
8672 <prgn>dpkg-deb</prgn>
8676 All manipulation of binary package files is done by
8677 <prgn>dpkg-deb</prgn>; it's the only program that has
8678 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8679 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8680 will spot that the options requested are appropriate to
8681 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8686 In order to create a binary package you must make a
8687 directory tree which contains all the files and directories
8688 you want to have in the filesystem data part of the package.
8689 In Debian-format source packages this directory is usually
8690 <file>debian/tmp</file>, relative to the top of the package's
8695 They should have the locations (relative to the root of the
8696 directory tree you're constructing) ownerships and
8697 permissions which you want them to have on the system when
8702 With current versions of <prgn>dpkg</prgn> the uid/username
8703 and gid/groupname mappings for the users and groups being
8704 used should be the same on the system where the package is
8705 built and the one where it is installed.
8709 You need to add one special directory to the root of the
8710 miniature filesystem tree you're creating:
8711 <prgn>DEBIAN</prgn>. It should contain the control
8712 information files, notably the binary package control file
8713 (see <ref id="pkg-controlfile">).
8717 The <prgn>DEBIAN</prgn> directory will not appear in the
8718 filesystem archive of the package, and so won't be installed
8719 by <prgn>dpkg</prgn> when the package is installed.
8723 When you've prepared the package, you should invoke:
8725 dpkg --build <var>directory</var>
8730 This will build the package in
8731 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8732 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8733 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8738 See the man page <manref name="dpkg-deb" section="8"> for details of how
8739 to examine the contents of this newly-created file. You may find the
8740 output of following commands enlightening:
8742 dpkg-deb --info <var>filename</var>.deb
8743 dpkg-deb --contents <var>filename</var>.deb
8744 dpkg --contents <var>filename</var>.deb
8746 To view the copyright file for a package you could use this command:
8748 dpkg --fsys-tarfile <var>filename</var>.deb | tar xO ./usr/share/doc/\*/copyright | pager
8753 <sect id="pkg-controlarea">
8754 <heading>Package control information files</heading>
8757 The control information portion of a binary package is a
8758 collection of files with names known to <prgn>dpkg</prgn>.
8759 It will treat the contents of these files specially - some
8760 of them contain information used by <prgn>dpkg</prgn> when
8761 installing or removing the package; others are scripts which
8762 the package maintainer wants <prgn>dpkg</prgn> to run.
8766 It is possible to put other files in the package control
8767 area, but this is not generally a good idea (though they
8768 will largely be ignored).
8772 Here is a brief list of the control info files supported by
8773 <prgn>dpkg</prgn> and a summary of what they're used for.
8778 <tag><tt>control</tt>
8781 This is the key description file used by
8782 <prgn>dpkg</prgn>. It specifies the package's name
8783 and version, gives its description for the user,
8784 states its relationships with other packages, and so
8785 forth. See <ref id="sourcecontrolfiles"> and
8786 <ref id="binarycontrolfiles">.
8790 It is usually generated automatically from information
8791 in the source package by the
8792 <prgn>dpkg-gencontrol</prgn> program, and with
8793 assistance from <prgn>dpkg-shlibdeps</prgn>.
8794 See <ref id="pkg-sourcetools">.
8798 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8803 These are exectuable files (usually scripts) which
8804 <prgn>dpkg</prgn> runs during installation, upgrade
8805 and removal of packages. They allow the package to
8806 deal with matters which are particular to that package
8807 or require more complicated processing than that
8808 provided by <prgn>dpkg</prgn>. Details of when and
8809 how they are called are in <ref id="maintainerscripts">.
8813 It is very important to make these scripts idempotent.
8814 See <ref id="idempotency">.
8818 The maintainer scripts are guaranteed to run with a
8819 controlling terminal and can interact with the user.
8820 See <ref id="controllingterminal">.
8824 <tag><tt>conffiles</tt>
8827 This file contains a list of configuration files which
8828 are to be handled automatically by <prgn>dpkg</prgn>
8829 (see <ref id="pkg-conffiles">). Note that not necessarily
8830 every configuration file should be listed here.
8833 <tag><tt>shlibs</tt>
8836 This file contains a list of the shared libraries
8837 supplied by the package, with dependency details for
8838 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8839 when it determines what dependencies are required in a
8840 package control file. The <tt>shlibs</tt> file format
8841 is described on <ref id="shlibs">.
8846 <sect id="pkg-controlfile">
8847 <heading>The main control information file: <tt>control</tt></heading>
8850 The most important control information file used by
8851 <prgn>dpkg</prgn> when it installs a package is
8852 <tt>control</tt>. It contains all the package's "vital
8857 The binary package control files of packages built from
8858 Debian sources are made by a special tool,
8859 <prgn>dpkg-gencontrol</prgn>, which reads
8860 <file>debian/control</file> and <file>debian/changelog</file> to
8861 find the information it needs. See <ref id="pkg-sourcepkg"> for
8866 The fields in binary package control files are listed in
8867 <ref id="binarycontrolfiles">.
8871 A description of the syntax of control files and the purpose
8872 of the fields is available in <ref id="controlfields">.
8877 <heading>Time Stamps</heading>
8880 See <ref id="timestamps">.
8885 <appendix id="pkg-sourcepkg">
8886 <heading>Source packages (from old Packaging Manual) </heading>
8889 The Debian binary packages in the distribution are generated
8890 from Debian sources, which are in a special format to assist
8891 the easy and automatic building of binaries.
8894 <sect id="pkg-sourcetools">
8895 <heading>Tools for processing source packages</heading>
8898 Various tools are provided for manipulating source packages;
8899 they pack and unpack sources and help build of binary
8900 packages and help manage the distribution of new versions.
8904 They are introduced and typical uses described here; see
8905 <manref name="dpkg-source" section="1"> for full
8906 documentation about their arguments and operation.
8910 For examples of how to construct a Debian source package,
8911 and how to use those utilities that are used by Debian
8912 source packages, please see the <prgn>hello</prgn> example
8916 <sect1 id="pkg-dpkg-source">
8918 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8923 This program is frequently used by hand, and is also
8924 called from package-independent automated building scripts
8925 such as <prgn>dpkg-buildpackage</prgn>.
8929 To unpack a package it is typically invoked with
8931 dpkg-source -x <var>.../path/to/filename</var>.dsc
8936 with the <file><var>filename</var>.tar.gz</file> and
8937 <file><var>filename</var>.diff.gz</file> (if applicable) in
8938 the same directory. It unpacks into
8939 <file><var>package</var>-<var>version</var></file>, and if
8941 <file><var>package</var>-<var>version</var>.orig</file>, in
8942 the current directory.
8946 To create a packed source archive it is typically invoked:
8948 dpkg-source -b <var>package</var>-<var>version</var>
8953 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8954 <file>.diff.gz</file> (if appropriate) in the current
8955 directory. <prgn>dpkg-source</prgn> does not clean the
8956 source tree first - this must be done separately if it is
8961 See also <ref id="pkg-sourcearchives">.</p>
8965 <sect1 id="pkg-dpkg-buildpackage">
8967 <prgn>dpkg-buildpackage</prgn> - overall package-building
8972 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8973 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8974 targets <tt>clean</tt>, <tt>build</tt> and
8975 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8976 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8977 source and binary package upload.
8981 It is usually invoked by hand from the top level of the
8982 built or unbuilt source directory. It may be invoked with
8983 no arguments; useful arguments include:
8984 <taglist compact="compact">
8985 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8988 Do not sign the <tt>.changes</tt> file or the
8989 source package <tt>.dsc</tt> file, respectively.</p>
8991 <tag><tt>-p<var>sign-command</var></tt></tag>
8994 Invoke <var>sign-command</var> instead of finding
8995 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8996 <var>sign-command</var> must behave just like
8997 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
8999 <tag><tt>-r<var>root-command</var></tt></tag>
9002 When root privilege is required, invoke the command
9003 <var>root-command</var>. <var>root-command</var>
9004 should invoke its first argument as a command, from
9005 the <prgn>PATH</prgn> if necessary, and pass its
9006 second and subsequent arguments to the command it
9007 calls. If no <var>root-command</var> is supplied
9008 then <var>dpkg-buildpackage</var> will take no
9009 special action to gain root privilege, so that for
9010 most packages it will have to be invoked as root to
9013 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9016 Two types of binary-only build and upload - see
9017 <manref name="dpkg-source" section="1">.
9024 <sect1 id="pkg-dpkg-gencontrol">
9026 <prgn>dpkg-gencontrol</prgn> - generates binary package
9031 This program is usually called from <file>debian/rules</file>
9032 (see <ref id="pkg-sourcetree">) in the top level of the source
9037 This is usually done just before the files and directories in the
9038 temporary directory tree where the package is being built have their
9039 permissions and ownerships set and the package is constructed using
9040 <prgn>dpkg-deb/</prgn>
9042 This is so that the control file which is produced has
9043 the right permissions
9048 <prgn>dpkg-gencontrol</prgn> must be called after all the
9049 files which are to go into the package have been placed in
9050 the temporary build directory, so that its calculation of
9051 the installed size of a package is correct.
9055 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9056 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9057 variable substitutions created by
9058 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9063 For a package which generates only one binary package, and
9064 which builds it in <file>debian/tmp</file> relative to the top
9065 of the source package, it is usually sufficient to call
9066 <prgn>dpkg-gencontrol</prgn>.
9070 Sources which build several binaries will typically need
9073 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9074 </example> The <tt>-P</tt> tells
9075 <prgn>dpkg-gencontrol</prgn> that the package is being
9076 built in a non-default directory, and the <tt>-p</tt>
9077 tells it which package's control file should be generated.
9081 <prgn>dpkg-gencontrol</prgn> also adds information to the
9082 list of files in <file>debian/files</file>, for the benefit of
9083 (for example) a future invocation of
9084 <prgn>dpkg-genchanges</prgn>.</p>
9087 <sect1 id="pkg-dpkg-shlibdeps">
9089 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9094 This program is usually called from <file>debian/rules</file>
9095 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9096 id="pkg-sourcetree">), in the top level of the source tree.
9100 Its arguments are executables.
9103 In a forthcoming dpkg version,
9104 <prgn>dpkg-shlibdeps</prgn> would be required to be
9105 called on shared libraries as well.
9108 They may be specified either in the locations in the
9109 source tree where they are created or in the locations
9110 in the temporary build tree where they are installed
9111 prior to binary package creation.
9113 </footnote> for which shared library dependencies should
9114 be included in the binary package's control file.
9118 If some of the found shared libraries should only
9119 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9120 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9121 by using the <tt>-d<var>dependency-field</var></tt> option
9122 before those executable(s). (Each <tt>-d</tt> option
9123 takes effect until the next <tt>-d</tt>.)
9127 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9128 output control file to be modified. Instead by default it
9129 adds to the <file>debian/substvars</file> file variable
9130 settings like <tt>shlibs:Depends</tt>. These variable
9131 settings must be referenced in dependency fields in the
9132 appropriate per-binary-package sections of the source
9137 For example, a package that generates an essential part
9138 which requires dependencies, and optional parts that
9139 which only require a recommendation, would separate those
9140 two sets of dependencies into two different fields.<footnote>
9141 At the time of writing, an example for this was the
9142 <package/xmms/ package, with Depends used for the xmms
9143 executable, Recommends for the plug-ins and Suggests for
9144 even more optional features provided by unzip.
9146 It can say in its <file>debian/rules</file>:
9148 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9149 -dRecommends <var>optionalpart anotheroptionalpart</var>
9151 and then in its main control file <file>debian/control</file>:
9154 Depends: ${shlibs:Pre-Depends}
9155 Recommends: ${shlibs:Recommends}
9161 Sources which produce several binary packages with
9162 different shared library dependency requirements can use
9163 the <tt>-p<var>varnameprefix</var></tt> option to override
9164 the default <tt>shlibs:</tt> prefix (one invocation of
9165 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9166 They can thus produce several sets of dependency
9167 variables, each of the form
9168 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9169 which can be referred to in the appropriate parts of the
9170 binary package control files.
9175 <sect1 id="pkg-dpkg-distaddfile">
9177 <prgn>dpkg-distaddfile</prgn> - adds a file to
9178 <file>debian/files</file>
9182 Some packages' uploads need to include files other than
9183 the source and binary package files.
9187 <prgn>dpkg-distaddfile</prgn> adds a file to the
9188 <file>debian/files</file> file so that it will be included in
9189 the <file>.changes</file> file when
9190 <prgn>dpkg-genchanges</prgn> is run.
9194 It is usually invoked from the <tt>binary</tt> target of
9195 <file>debian/rules</file>:
9197 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9199 The <var>filename</var> is relative to the directory where
9200 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9201 is usually the directory above the top level of the source
9202 tree. The <file>debian/rules</file> target should put the
9203 file there just before or just after calling
9204 <prgn>dpkg-distaddfile</prgn>.
9208 The <var>section</var> and <var>priority</var> are passed
9209 unchanged into the resulting <file>.changes</file> file.
9214 <sect1 id="pkg-dpkg-genchanges">
9216 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9221 This program is usually called by package-independent
9222 automatic building scripts such as
9223 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9228 It is usually called in the top level of a built source
9229 tree, and when invoked with no arguments will print out a
9230 straightforward <file>.changes</file> file based on the
9231 information in the source package's changelog and control
9232 file and the binary and source packages which should have
9238 <sect1 id="pkg-dpkg-parsechangelog">
9240 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9241 representation of a changelog
9245 This program is used internally by
9246 <prgn>dpkg-source</prgn> et al. It may also occasionally
9247 be useful in <file>debian/rules</file> and elsewhere. It
9248 parses a changelog, <file>debian/changelog</file> by default,
9249 and prints a control-file format representation of the
9250 information in it to standard output.
9254 <sect1 id="pkg-dpkg-architecture">
9256 <prgn>dpkg-architecture</prgn> - information about the build and
9261 This program can be used manually, but is also invoked by
9262 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9263 to set environment or make variables which specify the build and
9264 host architecture for the package building process.
9269 <sect id="pkg-sourcetree">
9270 <heading>The Debianised source tree</heading>
9273 The source archive scheme described later is intended to
9274 allow a Debianised source tree with some associated control
9275 information to be reproduced and transported easily. The
9276 Debianised source tree is a version of the original program
9277 with certain files added for the benefit of the
9278 Debianisation process, and with any other changes required
9279 made to the rest of the source code and installation
9284 The extra files created for Debian are in the subdirectory
9285 <file>debian</file> of the top level of the Debianised source
9286 tree. They are described below.
9289 <sect1 id="pkg-debianrules">
9290 <heading><file>debian/rules</file> - the main building script</heading>
9293 See <ref id="debianrules">.
9298 <sect1 id="pkg-dpkgchangelog">
9299 <heading><file>debian/changelog</file></heading>
9302 See <ref id="dpkgchangelog">.
9306 It is recommended that the entire changelog be encoded in the
9307 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9309 <url id="http://www.unicode.org/"
9310 name="Unicode">.<footnote>
9312 Support for Unicode, and specifically UTF-8, is
9313 steadily increasing among popular applications in
9314 Debian. For example, in unstable, GNOME 2 has
9315 excellent support (almost level 2) in almost all its
9316 applications; the big remaining one is gnome-terminal,
9317 of which one requires development versions in order to
9318 support UTF-8 (available in Debian experimental now if
9319 you want to play). I think that by the time sarge is
9320 released, UTF-8 support will start to hit critical
9323 I think it is fairly obvious that we need to
9324 eventually transition to UTF-8 for our package
9325 infrastructure; it is really the only sane charset in
9326 an international environment. Now, we can't switch to
9327 using UTF-8 for package control fields and the like
9328 until dpkg has better support, but one thing we can
9329 start doing today is requesting that Debian changelogs
9330 are UTF-8 encoded. At some point in time, we can start
9331 requiring them to do so.
9334 Checking for non-UTF8 characters in a changelog is
9335 trivial. Dump the file through
9336 <example>iconv -f utf-8 -t ucs-4</example>
9337 discard the output, and check the return
9338 value. If there are any characters in the stream
9339 which are invalid UTF-8 sequences, iconv will exit
9340 with an error code; and this will be the case for the
9341 vast majority of other character sets.
9346 <sect2><heading>Defining alternative changelog formats
9350 It is possible to use a different format to the standard
9351 one, by providing a parser for the format you wish to
9356 In order to have <tt>dpkg-parsechangelog</tt> run your
9357 parser, you must include a line within the last 40 lines
9358 of your file matching the Perl regular expression:
9359 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9360 parentheses should be the name of the format. For
9361 example, you might say:
9363 @@@ changelog-format: joebloggs @@@
9365 Changelog format names are non-empty strings of alphanumerics.
9369 If such a line exists then <tt>dpkg-parsechangelog</tt>
9370 will look for the parser as
9371 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9373 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9374 it is an error for it not to find it, or for it not to
9375 be an executable program. The default changelog format
9376 is <tt>dpkg</tt>, and a parser for it is provided with
9377 the <tt>dpkg</tt> package.
9381 The parser will be invoked with the changelog open on
9382 standard input at the start of the file. It should read
9383 the file (it may seek if it wishes) to determine the
9384 information required and return the parsed information
9385 to standard output in the form of a series of control
9386 fields in the standard format. By default it should
9387 return information about only the most recent version in
9388 the changelog; it should accept a
9389 <tt>-v<var>version</var></tt> option to return changes
9390 information from all versions present <em>strictly
9391 after</em> <var>version</var>, and it should then be an
9392 error for <var>version</var> not to be present in the
9398 <list compact="compact">
9399 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9400 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9401 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9402 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9403 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9404 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9405 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9410 If several versions are being returned (due to the use
9411 of <tt>-v</tt>), the urgency value should be of the
9412 highest urgency code listed at the start of any of the
9413 versions requested followed by the concatenated
9414 (space-separated) comments from all the versions
9415 requested; the maintainer, version, distribution and
9416 date should always be from the most recent version.
9420 For the format of the <tt>Changes</tt> field see
9421 <ref id="f-Changes">.
9425 If the changelog format which is being parsed always or
9426 almost always leaves a blank line between individual
9427 change notes these blank lines should be stripped out,
9428 so as to make the resulting output compact.
9432 If the changelog format does not contain date or package
9433 name information this information should be omitted from
9434 the output. The parser should not attempt to synthesise
9435 it or find it from other sources.
9439 If the changelog does not have the expected format the
9440 parser should exit with a nonzero exit status, rather
9441 than trying to muddle through and possibly generating
9446 A changelog parser may not interact with the user at
9452 <sect1 id="pkg-srcsubstvars">
9453 <heading><file>debian/substvars</file> and variable substitutions</heading>
9456 See <ref id="substvars">.
9462 <heading><file>debian/files</file></heading>
9465 See <ref id="debianfiles">.
9469 <sect1><heading><file>debian/tmp</file>
9473 This is the canonical temporary location for the
9474 construction of binary packages by the <tt>binary</tt>
9475 target. The directory <file>tmp</file> serves as the root of
9476 the filesystem tree as it is being constructed (for
9477 example, by using the package's upstream makefiles install
9478 targets and redirecting the output there), and it also
9479 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9480 id="pkg-bincreating">.
9484 If several binary packages are generated from the same
9485 source tree it is usual to use several
9486 <file>debian/tmp<var>something</var></file> directories, for
9487 example <file>tmp-a</file> or <file>tmp-doc</file>.
9491 Whatever <file>tmp</file> directories are created and used by
9492 <tt>binary</tt> must of course be removed by the
9493 <tt>clean</tt> target.</p></sect1>
9497 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9501 As it exists on the FTP site, a Debian source package
9502 consists of three related files. You must have the right
9503 versions of all three to be able to use them.
9508 <tag>Debian source control file - <tt>.dsc</tt></tag>
9510 This file is a control file used by <prgn>dpkg-source</prgn>
9511 to extract a source package.
9512 See <ref id="debiansourcecontrolfiles">.
9516 Original source archive -
9518 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9524 This is a compressed (with <tt>gzip -9</tt>)
9525 <prgn>tar</prgn> file containing the source code from
9526 the upstream authors of the program.
9531 Debianisation diff -
9533 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9539 This is a unified context diff (<tt>diff -u</tt>)
9540 giving the changes which are required to turn the
9541 original source into the Debian source. These changes
9542 may only include editing and creating plain files.
9543 The permissions of files, the targets of symbolic
9544 links and the characteristics of special files or
9545 pipes may not be changed and no files may be removed
9550 All the directories in the diff must exist, except the
9551 <file>debian</file> subdirectory of the top of the source
9552 tree, which will be created by
9553 <prgn>dpkg-source</prgn> if necessary when unpacking.
9557 The <prgn>dpkg-source</prgn> program will
9558 automatically make the <file>debian/rules</file> file
9559 executable (see below).</p></item>
9564 If there is no original source code - for example, if the
9565 package is specially prepared for Debian or the Debian
9566 maintainer is the same as the upstream maintainer - the
9567 format is slightly different: then there is no diff, and the
9569 <file><var>package</var>_<var>version</var>.tar.gz</file>,
9570 and preferably contains a directory named
9571 <file><var>package</var>-<var>version</var></file>.
9576 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9579 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9580 Debian source package. However, if it is not available it
9581 is possible to unpack a Debian source archive as follows:
9582 <enumlist compact="compact">
9585 Untar the tarfile, which will create a <file>.orig</file>
9589 <p>Rename the <file>.orig</file> directory to
9590 <file><var>package</var>-<var>version</var></file>.</p>
9594 Create the subdirectory <file>debian</file> at the top of
9595 the source tree.</p>
9597 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9599 <item><p>Untar the tarfile again if you want a copy of the original
9600 source code alongside the Debianised version.</p>
9605 It is not possible to generate a valid Debian source archive
9606 without using <prgn>dpkg-source</prgn>. In particular,
9607 attempting to use <prgn>diff</prgn> directly to generate the
9608 <file>.diff.gz</file> file will not work.
9612 <heading>Restrictions on objects in source packages</heading>
9615 The source package may not contain any hard links
9617 This is not currently detected when building source
9618 packages, but only when extracting
9622 Hard links may be permitted at some point in the
9623 future, but would require a fair amount of
9625 </footnote>, device special files, sockets or setuid or
9628 Setgid directories are allowed.
9633 The source packaging tools manage the changes between the
9634 original and Debianised source using <prgn>diff</prgn> and
9635 <prgn>patch</prgn>. Turning the original source tree as
9636 included in the <file>.orig.tar.gz</file> into the debianised
9637 source must not involve any changes which cannot be
9638 handled by these tools. Problematic changes which cause
9639 <prgn>dpkg-source</prgn> to halt with an error when
9640 building the source package are:
9641 <list compact="compact">
9642 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9644 <item><p>Changing the targets of symbolic links.</p>
9646 <item><p>Creating directories, other than <file>debian</file>.</p>
9648 <item><p>Changes to the contents of binary files.</p></item>
9649 </list> Changes which cause <prgn>dpkg-source</prgn> to
9650 print a warning but continue anyway are:
9651 <list compact="compact">
9654 Removing files, directories or symlinks.
9656 Renaming a file is not treated specially - it is
9657 seen as the removal of the old file (which
9658 generates a warning, but is otherwise ignored),
9659 and the creation of the new one.
9665 Changed text files which are missing the usual final
9666 newline (either in the original or the modified
9671 Changes which are not represented, but which are not detected by
9672 <prgn>dpkg-source</prgn>, are:
9673 <list compact="compact">
9674 <item><p>Changing the permissions of files (other than
9675 <file>debian/rules</file>) and directories.</p></item>
9680 The <file>debian</file> directory and <file>debian/rules</file>
9681 are handled specially by <prgn>dpkg-source</prgn> - before
9682 applying the changes it will create the <file>debian</file>
9683 directory, and afterwards it will make
9684 <file>debian/rules</file> world-exectuable.
9690 <appendix id="pkg-controlfields">
9691 <heading>Control files and their fields (from old Packaging Manual)</heading>
9694 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9695 data in a common format, known as control files. Binary and
9696 source packages have control data as do the <file>.changes</file>
9697 files which control the installation of uploaded files, and
9698 <prgn>dpkg</prgn>'s internal databases are in a similar
9703 <heading>Syntax of control files</heading>
9706 See <ref id="controlsyntax">.
9710 It is important to note that there are several fields which
9711 are optional as far as <prgn>dpkg</prgn> and the related
9712 tools are concerned, but which must appear in every Debian
9713 package, or whose omission may cause problems.
9718 <heading>List of fields</heading>
9721 See <ref id="controlfieldslist">.
9725 This section now contains only the fields that didn't belong
9726 to the Policy manual.
9729 <sect1 id="pkg-f-Filename">
9730 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9733 These fields in <tt>Packages</tt> files give the
9734 filename(s) of (the parts of) a package in the
9735 distribution directories, relative to the root of the
9736 Debian hierarchy. If the package has been split into
9737 several parts the parts are all listed in order, separated
9742 <sect1 id="pkg-f-Size">
9743 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9746 These fields in <file>Packages</file> files give the size (in
9747 bytes, expressed in decimal) and MD5 checksum of the
9748 file(s) which make(s) up a binary package in the
9749 distribution. If the package is split into several parts
9750 the values for the parts are listed in order, separated by
9755 <sect1 id="pkg-f-Status">
9756 <heading><tt>Status</tt></heading>
9759 This field in <prgn>dpkg</prgn>'s status file records
9760 whether the user wants a package installed, removed or
9761 left alone, whether it is broken (requiring
9762 reinstallation) or not and what its current state on the
9763 system is. Each of these pieces of information is a
9768 <sect1 id="pkg-f-Config-Version">
9769 <heading><tt>Config-Version</tt></heading>
9772 If a package is not installed or not configured, this
9773 field in <prgn>dpkg</prgn>'s status file records the last
9774 version of the package which was successfully
9779 <sect1 id="pkg-f-Conffiles">
9780 <heading><tt>Conffiles</tt></heading>
9783 This field in <prgn>dpkg</prgn>'s status file contains
9784 information about the automatically-managed configuration
9785 files held by a package. This field should <em>not</em>
9786 appear anywhere in a package!
9791 <heading>Obsolete fields</heading>
9794 These are still recognised by <prgn>dpkg</prgn> but should
9795 not appear anywhere any more.
9797 <taglist compact="compact">
9799 <tag><tt>Revision</tt></tag>
9800 <tag><tt>Package-Revision</tt></tag>
9801 <tag><tt>Package_Revision</tt></tag>
9803 The Debian revision part of the package version was
9804 at one point in a separate control file field. This
9805 field went through several names.
9808 <tag><tt>Recommended</tt></tag>
9809 <item>Old name for <tt>Recommends</tt>.</item>
9811 <tag><tt>Optional</tt></tag>
9812 <item>Old name for <tt>Suggests</tt>.</item>
9814 <tag><tt>Class</tt></tag>
9815 <item>Old name for <tt>Priority</tt>.</item>
9824 <appendix id="pkg-conffiles">
9825 <heading>Configuration file handling (from old Packaging Manual)</heading>
9828 <prgn>dpkg</prgn> can do a certain amount of automatic
9829 handling of package configuration files.
9833 Whether this mechanism is appropriate depends on a number of
9834 factors, but basically there are two approaches to any
9835 particular configuration file.
9839 The easy method is to ship a best-effort configuration in the
9840 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9841 handle updates. If the user is unlikely to want to edit the
9842 file, but you need them to be able to without losing their
9843 changes, and a new package with a changed version of the file
9844 is only released infrequently, this is a good approach.
9848 The hard method is to build the configuration file from
9849 scratch in the <prgn>postinst</prgn> script, and to take the
9850 responsibility for fixing any mistakes made in earlier
9851 versions of the package automatically. This will be
9852 appropriate if the file is likely to need to be different on
9856 <sect><heading>Automatic handling of configuration files by
9861 A package may contain a control area file called
9862 <tt>conffiles</tt>. This file should be a list of filenames
9863 of configuration files needing automatic handling, separated
9864 by newlines. The filenames should be absolute pathnames,
9865 and the files referred to should actually exist in the
9870 When a package is upgraded <prgn>dpkg</prgn> will process
9871 the configuration files during the configuration stage,
9872 shortly before it runs the package's <prgn>postinst</prgn>
9877 For each file it checks to see whether the version of the
9878 file included in the package is the same as the one that was
9879 included in the last version of the package (the one that is
9880 being upgraded from); it also compares the version currently
9881 installed on the system with the one shipped with the last
9886 If neither the user nor the package maintainer has changed
9887 the file, it is left alone. If one or the other has changed
9888 their version, then the changed version is preferred - i.e.,
9889 if the user edits their file, but the package maintainer
9890 doesn't ship a different version, the user's changes will
9891 stay, silently, but if the maintainer ships a new version
9892 and the user hasn't edited it the new version will be
9893 installed (with an informative message). If both have
9894 changed their version the user is prompted about the problem
9895 and must resolve the differences themselves.
9899 The comparisons are done by calculating the MD5 message
9900 digests of the files, and storing the MD5 of the file as it
9901 was included in the most recent version of the package.
9905 When a package is installed for the first time
9906 <prgn>dpkg</prgn> will install the file that comes with it,
9907 unless that would mean overwriting a file already on the
9912 However, note that <prgn>dpkg</prgn> will <em>not</em>
9913 replace a conffile that was removed by the user (or by a
9914 script). This is necessary because with some programs a
9915 missing file produces an effect hard or impossible to
9916 achieve in another way, so that a missing file needs to be
9917 kept that way if the user did it.
9921 Note that a package should <em>not</em> modify a
9922 <prgn>dpkg</prgn>-handled conffile in its maintainer
9923 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9924 the user confusing and possibly dangerous options for
9925 conffile update when the package is upgraded.</p>
9928 <sect><heading>Fully-featured maintainer script configuration
9933 For files which contain site-specific information such as
9934 the hostname and networking details and so forth, it is
9935 better to create the file in the package's
9936 <prgn>postinst</prgn> script.
9940 This will typically involve examining the state of the rest
9941 of the system to determine values and other information, and
9942 may involve prompting the user for some information which
9943 can't be obtained some other way.
9947 When using this method there are a couple of important
9948 issues which should be considered:
9952 If you discover a bug in the program which generates the
9953 configuration file, or if the format of the file changes
9954 from one version to the next, you will have to arrange for
9955 the postinst script to do something sensible - usually this
9956 will mean editing the installed configuration file to remove
9957 the problem or change the syntax. You will have to do this
9958 very carefully, since the user may have changed the file,
9959 perhaps to fix the very problem that your script is trying
9960 to deal with - you will have to detect these situations and
9961 deal with them correctly.
9965 If you do go down this route it's probably a good idea to
9966 make the program that generates the configuration file(s) a
9967 separate program in <file>/usr/sbin</file>, by convention called
9968 <file><var>package</var>config</file> and then run that if
9969 appropriate from the post-installation script. The
9970 <tt><var>package</var>config</tt> program should not
9971 unquestioningly overwrite an existing configuration - if its
9972 mode of operation is geared towards setting up a package for
9973 the first time (rather than any arbitrary reconfiguration
9974 later) you should have it check whether the configuration
9975 already exists, and require a <tt>--force</tt> flag to
9976 overwrite it.</p></sect>
9979 <appendix id="pkg-alternatives"><heading>Alternative versions of
9980 an interface - <prgn>update-alternatives</prgn> (from old
9985 When several packages all provide different versions of the
9986 same program or file it is useful to have the system select a
9987 default, but to allow the system administrator to change it
9988 and have their decisions respected.
9992 For example, there are several versions of the <prgn>vi</prgn>
9993 editor, and there is no reason to prevent all of them from
9994 being installed at once, each under their own name
9995 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9996 Nevertheless it is desirable to have the name <tt>vi</tt>
9997 refer to something, at least by default.
10001 If all the packages involved cooperate, this can be done with
10002 <prgn>update-alternatives</prgn>.
10006 Each package provides its own version under its own name, and
10007 calls <prgn>update-alternatives</prgn> in its postinst to
10008 register its version (and again in its prerm to deregister
10013 See the man page <manref name="update-alternatives"
10014 section="8"> for details.
10018 If <prgn>update-alternatives</prgn> does not seem appropriate
10019 you may wish to consider using diversions instead.</p>
10022 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10023 package's version of a file (from old Packaging Manual)
10027 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10028 when it reinstalls the package it belongs to, and to have it
10029 put the file from the package somewhere else instead.
10033 This can be used locally to override a package's version of a
10034 file, or by one package to override another's version (or
10035 provide a wrapper for it).
10039 Before deciding to use a diversion, read <ref
10040 id="pkg-alternatives"> to see if you really want a diversion
10041 rather than several alternative versions of a program.
10045 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10046 and updated by a special program <prgn>dpkg-divert</prgn>.
10047 Please see <manref name="dpkg-divert" section="8"> for full
10048 details of its operation.
10052 When a package wishes to divert a file from another, it should
10053 call <prgn>dpkg-divert</prgn> in its preinst to add the
10054 diversion and rename the existing file. For example,
10055 supposing that a <prgn>smailwrapper</prgn> package wishes to
10056 install a wrapper around <file>/usr/sbin/smail</file>:
10058 if [ install = "$1" ]; then
10059 dpkg-divert --package smailwrapper --add --rename \
10060 --divert /usr/sbin/smail.real /usr/sbin/smail
10062 </example> Testing <tt>$1</tt> is necessary so that the script
10063 doesn't try to add the diversion again when
10064 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10065 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10066 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10067 get installed as the true version.
10071 The postrm has to do the reverse:
10073 if [ remove = "$1" ]; then
10074 dpkg-divert --package smailwrapper --remove --rename \
10075 --divert /usr/sbin/smail.real /usr/sbin/smail
10081 Do not attempt to divert a file which is vitally important for
10082 the system's operation - when using <prgn>dpkg-divert</prgn>
10083 there is a time, after it has been diverted but before
10084 <prgn>dpkg</prgn> has installed the new version, when the file
10085 does not exist.</p>
10090 <!-- vim:set ai et sts=2 sw=2 tw=76: -->