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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy" id="http://packages.debian.org/debian-policy"></package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>.
168 Also available from the same directory are several other
169 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
170 and <file>policy.ps.gz</file>.
174 The <package>debian-policy</package> package also includes the file
175 <file>upgrading-checklist.txt</file> which indicates policy
176 changes between versions of this document.
181 <heading>Authors and Maintainers</heading>
184 Originally called "Debian GNU/Linux Policy Manual", this
185 manual was initially written in 1996 by Ian Jackson.
186 It was revised on November 27th, 1996 by David A. Morris.
187 Christian Schwarz added new sections on March 15th, 1997,
188 and reworked/restructured it in April-July 1997.
189 Christoph Lameter contributed the "Web Standard".
190 Julian Gilbey largely restructured it in 2001.
194 Since September 1998, the responsibility for the contents of
195 this document lies on the <url name="debian-policy mailing list"
196 id="mailto:debian-policy@lists.debian.org">. Proposals
197 are discussed there and inserted into policy after a certain
198 consensus is established.
199 <!-- insert shameless policy-process plug here eventually -->
200 The actual editing is done by a group of maintainers that have
201 no editorial powers. These are the current maintainers:
204 <item>Julian Gilbey</item>
205 <item>Branden Robinson</item>
206 <item>Josip Rodin</item>
207 <item>Manoj Srivastava</item>
212 While the authors of this document have tried hard to avoid
213 typos and other errors, these do still occur. If you discover
214 an error in this manual or if you want to give any
215 comments, suggestions, or criticisms please send an email to
216 the Debian Policy List,
217 <email>debian-policy@lists.debian.org</email>, or submit a
218 bug report against the <tt>debian-policy</tt> package.
222 Please do not try to reach the individual authors or maintainers
223 of the Policy Manual regarding changes to the Policy.
228 <heading>Related documents</heading>
231 There are several other documents other than this Policy Manual
232 that are necessary to fully understand some Debian policies and
237 The external "sub-policy" documents are referred to in:
238 <list compact="compact">
239 <item><ref id="fhs"></item>
240 <item><ref id="virtual_pkg"></item>
241 <item><ref id="menus"></item>
242 <item><ref id="mime"></item>
243 <item><ref id="perl"></item>
244 <item><ref id="maintscriptprompt"></item>
245 <item><ref id="emacs"></item>
250 In addition to those, which carry the weight of policy, there
251 is the Debian Developer's Reference. This document describes
252 procedures and resources for Debian developers, but it is
253 <em>not</em> normative; rather, it includes things that don't
254 belong into the Policy, such as best practices for developers.
258 The Developer's Reference is available in the
259 <package>developers-reference</package> package.
260 It's also available from the Debian web mirrors at
261 <tt><url name="/doc/developers-reference/"
262 id="http://www.debian.org/doc/developers-reference/"></tt>.
270 <heading>The Debian Archive</heading>
273 The Debian GNU/Linux system is maintained and distributed as a
274 collection of <em>packages</em>. Since there are so many of
275 them (currently well over 6000), they are split into
276 <em>sections</em> and given <em>priorities</em> to simplify
277 the handling of them.
281 The effort of the Debian project is to build a free operating
282 system, but not every package we want to make accessible is
283 <em>free</em> in our sense (see the Debian Free Software
284 Guidelines, below), or may be imported/exported without
285 restrictions. Thus, the archive is split into the sections
286 based on their licenses and other restrictions.
290 The aims of this are:
292 <list compact="compact">
293 <item>to allow us to make as much software available as we can</item>
294 <item>to allow us to encourage everyone to write free software,
296 <item>to allow us to make it easy for people to produce
297 CD-ROMs of our system without violating any licenses,
298 import/export restrictions, or any other laws.</item>
303 The <em>main</em> and the <em>non-US/main</em> sections
304 together form the <em>Debian GNU/Linux distribution</em>.
308 Packages in the other sections are not considered to be part
309 of the Debian distribution, although we support their use and
310 provide infrastructure for them (such as our bug-tracking
311 system and mailing lists). This Debian Policy Manual applies
312 to these packages as well.
316 <heading>The Debian Free Software Guidelines</heading>
318 The Debian Free Software Guidelines (DFSG) form our
319 definition of "free software". These are:
321 <tag>Free Redistribution
324 The license of a Debian component may not restrict any
325 party from selling or giving away the software as a
326 component of an aggregate software distribution
327 containing programs from several different
328 sources. The license may not require a royalty or
329 other fee for such sale.
334 The program must include source code, and must allow
335 distribution in source code as well as compiled form.
340 The license must allow modifications and derived
341 works, and must allow them to be distributed under the
342 same terms as the license of the original software.
344 <tag>Integrity of The Author's Source Code
347 The license may restrict source-code from being
348 distributed in modified form <em>only</em> if the
349 license allows the distribution of "patch files"
350 with the source code for the purpose of modifying the
351 program at build time. The license must explicitly
352 permit distribution of software built from modified
353 source code. The license may require derived works to
354 carry a different name or version number from the
355 original software. (This is a compromise. The Debian
356 Project encourages all authors to not restrict any
357 files, source or binary, from being modified.)
359 <tag>No Discrimination Against Persons or Groups
362 The license must not discriminate against any person
365 <tag>No Discrimination Against Fields of Endeavor
368 The license must not restrict anyone from making use
369 of the program in a specific field of endeavor. For
370 example, it may not restrict the program from being
371 used in a business, or from being used for genetic
374 <tag>Distribution of License
377 The rights attached to the program must apply to all
378 to whom the program is redistributed without the need
379 for execution of an additional license by those
382 <tag>License Must Not Be Specific to Debian
385 The rights attached to the program must not depend on
386 the program's being part of a Debian system. If the
387 program is extracted from Debian and used or
388 distributed without Debian but otherwise within the
389 terms of the program's license, all parties to whom
390 the program is redistributed must have the same
391 rights as those that are granted in conjunction with
394 <tag>License Must Not Contaminate Other Software
397 The license must not place restrictions on other
398 software that is distributed along with the licensed
399 software. For example, the license must not insist
400 that all other programs distributed on the same medium
401 must be free software.
403 <tag>Example Licenses
406 The "GPL," "BSD," and "Artistic" licenses are examples of
407 licenses that we consider <em>free</em>.
414 <heading>Sections</heading>
417 <heading>The main section</heading>
420 Every package in <em>main</em> and <em>non-US/main</em>
421 must comply with the DFSG (Debian Free Software
426 In addition, the packages in <em>main</em>
427 <list compact="compact">
429 must not require a package outside of <em>main</em>
430 for compilation or execution (thus, the package must
431 not declare a "Depends", "Recommends", or
432 "Build-Depends" relationship on a non-<em>main</em>
436 must not be so buggy that we refuse to support them,
440 must meet all policy requirements presented in this
447 Similarly, the packages in <em>non-US/main</em>
448 <list compact="compact">
450 must not require a package outside of <em>main</em>
451 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
458 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
479 must not be so buggy that we refuse to support them,
483 must meet all policy requirements presented in this
490 Furthermore, packages in <em>contrib</em> must not require
491 a package in a <em>non-US</em> section for compilation or
496 Examples of packages which would be included in
497 <em>contrib</em> or <em>non-US/contrib</em> are:
498 <list compact="compact">
500 free packages which require <em>contrib</em>,
501 <em>non-free</em> packages or packages which are not
502 in our archive at all for compilation or execution,
506 wrapper packages or other sorts of free accessories for
513 <sect1 id="non-free">
514 <heading>The non-free section</heading>
517 Packages must be placed in <em>non-free</em> or
518 <em>non-US/non-free</em> if they are not compliant with
519 the DFSG or are encumbered by patents or other legal
520 issues that make their distribution problematic.
524 In addition, the packages in <em>non-free</em> and
525 <em>non-US/non-free</em>
526 <list compact="compact">
528 must not be so buggy that we refuse to support them,
532 must meet all policy requirements presented in this
533 manual that it is possible for them to meet.
535 It is possible that there are policy
536 requirements which the package is unable to
537 meet, for example, if the source is
538 unavailable. These situations will need to be
539 handled on a case-by-case basis.
547 <heading>The non-US sections</heading>
550 Non-free programs with cryptographic program code need to
551 be stored on the <em>non-us</em> server because of export
552 restrictions of the U.S.
556 Programs which use patented algorithms that have a
557 restricted license also need to be stored on "non-us",
558 since that is located in a country where it is not allowed
559 to patent algorithms.
563 A package depends on another package which is distributed
564 via the non-us server has to be stored on the non-us
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of
575 its copyright and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Subsections</heading>
653 The packages in the sections <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further
655 into <em>subsections</em> to simplify handling.
659 The section and subsection for each package should be
660 specified in the package's <tt>Section</tt> control
661 record (see <ref id="f-Section">).
662 However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
668 <em>subsection</em> if the package is in the
669 <em>main</em> section,
672 <em>section/subsection</em> if the package is in
673 the <em>contrib</em> or <em>non-free</em> section,
677 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
678 <tt>non-US/non-free</tt> if the package is in
679 <em>non-US/main</em>, <em>non-US/contrib</em> or
680 <em>non-US/non-free</em> respectively.
686 The Debian archive maintainers provide the authoritative
687 list of subsections. At present, they are:
688 <em>admin</em>, <em>base</em>, <em>comm</em>,
689 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
690 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
691 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
692 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
693 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
694 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
695 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
696 <em>otherosfs</em>, <em>perl</em>, <em>python</em>
697 <em>science</em>, <em>shells</em>,
698 <em>sound</em>, <em>tex</em>, <em>text</em>,
699 <em>utils</em>, <em>web</em>, <em>x11</em>.
703 <sect id="priorities">
704 <heading>Priorities</heading>
707 Each package should have a <em>priority</em> value, which is
708 included in the package's <em>control record</em>
709 (see <ref id="f-Priority">).
710 This information is used by the Debian package management tools to
711 separate high-priority packages from less-important packages.
715 The following <em>priority levels</em> are recognised by the
716 Debian package management tools.
718 <tag><tt>required</tt></tag>
720 Packages which are necessary for the proper
721 functioning of the system. You must not remove these
722 packages or your system may become totally broken and
723 you may not even be able to use <prgn>dpkg</prgn> to
724 put things back. Systems with only the
725 <tt>required</tt> packages are probably unusable, but
726 they do have enough functionality to allow the
727 sysadmin to boot and install more software.
729 <tag><tt>important</tt></tag>
731 Important programs, including those which one would
732 expect to find on any Unix-like system. If the
733 expectation is that an experienced Unix person who
734 found it missing would say "What on earth is going on,
735 where is <prgn>foo</prgn>?", it must be an
736 <tt>important</tt> package.<footnote>
737 This is an important criterion because we are
738 trying to produce, amongst other things, a free
741 Other packages without which the system will not run
742 well or be usable must also have priority
743 <tt>important</tt>. This does
744 <em>not</em> include Emacs, the X Window System, TeX
745 or any other large applications. The
746 <tt>important</tt> packages are just a bare minimum of
747 commonly-expected and necessary tools.
749 <tag><tt>standard</tt></tag>
751 These packages provide a reasonably small but not too
752 limited character-mode system. This is what will be
753 installed by default if the user doesn't select anything
754 else. It doesn't include many large applications.
756 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
767 <tag><tt>extra</tt></tag>
769 This contains all packages that conflict with others
770 with required, important, standard or optional
771 priorities, or are only likely to be useful if you
772 already know what they are or have specialised
779 Packages must not depend on packages with lower priority
780 values (excluding build-time dependencies). In order to
781 ensure this, the priorities of one or more packages may need
790 <heading>Binary packages</heading>
793 The Debian GNU/Linux distribution is based on the Debian
794 package management system, called <prgn>dpkg</prgn>. Thus,
795 all packages in the Debian distribution must be provided
796 in the <tt>.deb</tt> file format.
800 <heading>The package name</heading>
803 Every package must have a name that's unique within the Debian
808 The package name is included in the control field
809 <tt>Package</tt>, the format of which is described
810 in <ref id="f-Package">.
811 The package name is also included as a part of the file name
812 of the <tt>.deb</tt> file.
817 <heading>The version of a package</heading>
820 Every package has a version number recorded in its
821 <tt>Version</tt> control file field, described in
822 <ref id="f-Version">.
826 The package management system imposes an ordering on version
827 numbers, so that it can tell whether packages are being up- or
828 downgraded and so that package system front end applications
829 can tell whether a package it finds available is newer than
830 the one installed on the system. The version number format
831 has the most significant parts (as far as comparison is
832 concerned) at the beginning.
836 If an upstream package has problematic version numbers they
837 should be converted to a sane form for use in the
838 <tt>Version</tt> field.
842 <heading>Version numbers based on dates</heading>
845 In general, Debian packages should use the same version
846 numbers as the upstream sources.
850 However, in some cases where the upstream version number is
851 based on a date (e.g., a development "snapshot" release) the
852 package management system cannot handle these version
853 numbers without epochs. For example, dpkg will consider
854 "96May01" to be greater than "96Dec24".
858 To prevent having to use epochs for every new upstream
859 version, the version number should be changed to the
860 following format in such cases: "19960501", "19961224". It
861 is up to the maintainer whether he/she wants to bother the
862 upstream maintainer to change the version numbers upstream,
867 Note that other version formats based on dates which are
868 parsed correctly by the package management system should
869 <em>not</em> be changed.
873 Native Debian packages (i.e., packages which have been
874 written especially for Debian) whose version numbers include
875 dates should always use the "YYYYMMDD" format.
882 <heading>The maintainer of a package</heading>
885 Every package must have a Debian maintainer (the
886 maintainer may be one person or a group of people
887 reachable from a common email address, such as a mailing
888 list). The maintainer is responsible for ensuring that
889 the package is placed in the appropriate distributions.
893 The maintainer must be specified in the
894 <tt>Maintainer</tt> control field with their correct name
895 and a working email address. If one person maintains
896 several packages, he/she should try to avoid having
897 different forms of their name and email address in
898 the <tt>Maintainer</tt> fields of those packages.
902 The format of the <tt>Maintainer</tt> control field is
903 described in <ref id="f-Maintainer">.
907 If the maintainer of a package quits from the Debian
908 project, "Debian QA Group"
909 <email>packages@qa.debian.org</email> takes over the
910 maintainership of the package until someone else
911 volunteers for that task. These packages are called
912 <em>orphaned packages</em>.<footnote>
913 The detailed procedure for doing this gracefully can
914 be found in the Debian Developer's Reference,
915 see <ref id="related">.
920 <sect id="descriptions">
921 <heading>The description of a package</heading>
924 Every Debian package must have an extended description
925 stored in the appropriate field of the control record.
926 The technical information about the format of the
927 <tt>Description</tt> field is in <ref id="f-Description">.
931 The description should describe the package (the program) to a
932 user (system administrator) who has never met it before so that
933 they have enough information to decide whether they want to
934 install it. This description should not just be copied verbatim
935 from the program's documentation.
939 Put important information first, both in the synopsis and
940 extended description. Sometimes only the first part of the
941 synopsis or of the description will be displayed. You can
942 assume that there will usually be a way to see the whole
943 extended description.
947 The description should also give information about the
948 significant dependencies and conflicts between this package
949 and others, so that the user knows why these dependencies and
950 conflicts have been declared.
954 Instructions for configuring or using the package should
955 not be included (that is what installation scripts,
956 manual pages, info files, etc., are for). Copyright
957 statements and other administrivia should not be included
958 either (that is what the copyright file is for).
961 <sect1 id="synopsis"><heading>The single line synopsis</heading>
964 The single line synopsis should be kept brief - certainly
969 Do not include the package name in the synopsis line. The
970 display software knows how to display this already, and you
971 do not need to state it. Remember that in many situations
972 the user may only see the synopsis line - make it as
973 informative as you can.
978 <sect1 id="extendeddesc"><heading>The extended description</heading>
981 Do not try to continue the single line synopsis into the
982 extended description. This will not work correctly when
983 the full description is displayed, and makes no sense
984 where only the summary (the single line synopsis) is
989 The extended description should describe what the package
990 does and how it relates to the rest of the system (in terms
991 of, for example, which subsystem it is which part of).
995 The description field needs to make sense to anyone, even
996 people who have no idea about any of the things the
997 package deals with.<footnote>
998 The blurb that comes with a program in its
999 announcements and/or <prgn>README</prgn> files is
1000 rarely suitable for use in a description. It is
1001 usually aimed at people who are already in the
1002 community where the package is used.
1011 <heading>Dependencies</heading>
1014 Every package must specify the dependency information
1015 about other packages that are required for the first to
1020 For example, a dependency entry must be provided for any
1021 shared libraries required by a dynamically-linked executable
1022 binary in a package.
1026 Packages are not required to declare any dependencies they
1027 have on other packages which are marked <tt>Essential</tt>
1028 (see below), and should not do so unless they depend on a
1029 particular version of that package.
1033 Sometimes, a package requires another package to be installed
1034 <em>and</em> configured before it can be installed. In this
1035 case, you must specify a <tt>Pre-Depends</tt> entry for
1040 You should not specify a <tt>Pre-Depends</tt> entry for a
1041 package before this has been discussed on the
1042 <tt>debian-devel</tt> mailing list and a consensus about
1043 doing that has been reached.
1047 The format of the package interrelationship control fields is
1048 described in <ref id="relationships">.
1052 <sect id="virtual_pkg">
1053 <heading>Virtual packages</heading>
1056 Sometimes, there are several packages which offer
1057 more-or-less the same functionality. In this case, it's
1058 useful to define a <em>virtual package</em> whose name
1059 describes that common functionality. (The virtual
1060 packages only exist logically, not physically; that's why
1061 they are called <em>virtual</em>.) The packages with this
1062 particular function will then <em>provide</em> the virtual
1063 package. Thus, any other package requiring that function
1064 can simply depend on the virtual package without having to
1065 specify all possible packages individually.
1069 All packages should use virtual package names where
1070 appropriate, and arrange to create new ones if necessary.
1071 They should not use virtual package names (except privately,
1072 amongst a cooperating group of packages) unless they have
1073 been agreed upon and appear in the list of virtual package
1074 names. (See also <ref id="virtual">)
1078 The latest version of the authoritative list of virtual
1079 package names can be found in the <tt>debian-policy</tt> package.
1080 It is also available from the Debian web mirrors at
1081 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1082 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
1083 and from the Debian archive mirrors at
1084 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
1085 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
1089 The procedure for updating the list is described in the preface
1096 <heading>Base system</heading>
1099 The <tt>base system</tt> is a minimum subset of the Debian
1100 GNU/Linux system that is installed before everything else
1101 on a new system. Thus, only very few packages are allowed
1102 to go into the <tt>base</tt> section to keep the required
1103 disk usage very small.
1107 Most of these packages will have the priority value
1108 <tt>required</tt> or at least <tt>important</tt>, and many
1109 of them will be tagged <tt>essential</tt> (see below).
1114 <heading>Essential packages</heading>
1117 Some packages are tagged <tt>essential</tt> for a system
1118 using the <tt>Essential</tt> control file field.
1119 The format of the <tt>Essential</tt> control field is
1120 described in <ref id="f-Essential">.
1124 Since these packages cannot be easily removed (one has to
1125 specify an extra <em>force option</em> to
1126 <prgn>dpkg</prgn> to do so), this flag must not be used
1127 unless absolutely necessary. A shared library package
1128 must not be tagged <tt>essential</tt>; dependencies will
1129 prevent its premature removal, and we need to be able to
1130 remove it when it has been superseded.
1134 Since dpkg will not prevent upgrading of other packages
1135 while an <tt>essential</tt> package is in an unconfigured
1136 state, all <tt>essential</tt> packages must supply all of
1137 their core functionality even when unconfigured. If the
1138 package cannot satisfy this requirement it must not be
1139 tagged as essential, and any packages depending on this
1140 package must instead have explicit dependency fields as
1145 You must not tag any packages <tt>essential</tt> before
1146 this has been discussed on the <tt>debian-devel</tt>
1147 mailing list and a consensus about doing that has been
1153 <heading>Tasks</heading>
1156 The Debian install process allows the user to choose from
1157 a number of common tasks which a Debian system can be used to
1158 perform. Selecting a task with <prgn>tasksel</prgn> causes
1159 a set of packages that are useful in performing that task to be
1164 This set of packages is all available packages which have the
1165 name of the selected task in the <tt>Task</tt> field of their
1166 control file. The format of this field is a list of tasks,
1167 separated by commas.
1171 You should not tag any packages as belonging to a task
1172 before this has been discussed on the
1173 <em>debian-devel</em> mailing list and a consensus about
1174 doing that has been reached.
1178 For third parties (and historical reasons), tasksel also
1179 supports constructing tasks based on <em>task
1180 packages</em>. These are packages whose names begin with
1181 <em>task-</em>. Task packages should not be included in the
1186 <sect id="maintscripts">
1187 <heading>Maintainer Scripts</heading>
1190 The package installation scripts should avoid producing
1191 output which it is unnecessary for the user to see and
1192 should rely on <prgn>dpkg</prgn> to stave off boredom on
1193 the part of a user installing many packages. This means,
1194 amongst other things, using the <tt>--quiet</tt> option on
1195 <prgn>install-info</prgn>.
1199 Errors which occur during the execution of an installation
1200 script must be checked and the installation must not
1201 continue after an error.
1205 Note that in general <ref id="scripts"> applies to package
1206 maintainer scripts, too.
1210 You should not use <prgn>dpkg-divert</prgn> on a file
1211 belonging to another package without consulting the
1212 maintainer of that package first.
1216 All packages which supply an instance of a common command
1217 name (or, in general, filename) should generally use
1218 <prgn>update-alternatives</prgn>, so that they may be
1219 installed together. If <prgn>update-alternatives</prgn>
1220 is not used, then each package must use
1221 <tt>Conflicts</tt> to ensure that other packages are
1222 de-installed. (In this case, it may be appropriate to
1223 specify a conflict against earlier versions of something
1224 that previously did not use
1225 <prgn>update-alternatives</prgn>; this is an exception to
1226 the usual rule that versioned conflicts should be
1230 <sect1 id="maintscriptprompt">
1231 <heading>Prompting in maintainer scripts</heading>
1233 Package maintainer scripts may prompt the user if
1234 necessary. Prompting should be done by communicating
1235 through a program, such as <prgn>debconf</prgn>, which
1236 conforms to the Debian Configuration management
1237 specification, version 2 or higher. Prompting the user by
1238 other means, such as by hand<footnote>
1239 From the Jargon file: by hand 2. By extension,
1240 writing code which does something in an explicit or
1241 low-level way for which a presupplied library
1242 (<em>debconf, in this instance</em>) routine ought
1243 to have been available.
1244 </footnote>, is now deprecated.
1248 The Debian Configuration management specification is included
1249 in the <file>debconf_specification</file> files in the
1250 <package>debian-policy</package> package.
1251 It is also available from the Debian web mirrors at
1252 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1253 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1254 and from the Debian archive mirrors at
1255 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1256 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1260 Packages which use the Debian Configuration management
1261 specification may contain an additional
1262 <prgn>config</prgn> script and a <tt>templates</tt>
1263 file in their control archive<footnote>
1264 The control.tar.gz inside the .deb.
1265 See <manref name="deb" section="5">.
1267 The <prgn>config</prgn> script might be run before the
1268 <prgn>preinst</prgn> script, and before the package is unpacked
1269 or any of its dependencies or pre-dependancies are satisfied.
1270 Therefore it must work using only the tools present in
1271 <em>essential</em> packages.<footnote>
1272 <package>Debconf</package> or another tool that
1273 implements the Debian Configuration management
1274 specification will also be installed, and any
1275 versioned dependencies on it will be satisfied
1276 before preconfiguration begins.
1281 Packages should try to minimize the amount of prompting
1282 they need to do, and they should ensure that the user
1283 will only ever be asked each question once. This means
1284 that packages should try to use appropriate shared
1285 configuration files (such as <file>/etc/papersize</file> and
1286 <file>/etc/news/server</file>), and shared
1287 <package>debconf</package> variables rather than each
1288 prompting for their own list of required pieces of
1293 It also means that an upgrade should not ask the same
1294 questions again, unless the user has used
1295 <tt>dpkg --purge</tt> to remove the package's configuration.
1296 The answers to configuration questions should be stored in an
1297 appropriate place in <file>/etc</file> so that the user can
1298 modify them, and how this has been done should be
1303 If a package has a vitally important piece of
1304 information to pass to the user (such as "don't run me
1305 as I am, you must edit the following configuration files
1306 first or you risk your system emitting badly-formatted
1307 messages"), it should display this in the
1308 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1309 prompt the user to hit return to acknowledge the
1310 message. Copyright messages do not count as vitally
1311 important (they belong in
1312 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1313 neither do instructions on how to use a program (these
1314 should be in on-line documentation, where all the users
1319 Any necessary prompting should almost always be confined
1320 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1321 script. If it is done in the <prgn>postinst</prgn>, it
1322 should be protected with a conditional so that
1323 unnecessary prompting doesn't happen if a package's
1324 installation fails and the <prgn>postinst</prgn> is
1325 called with <tt>abort-upgrade</tt>,
1326 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1336 <heading>Source packages</heading>
1338 <sect id="standardsversion">
1339 <heading>Standards conformance</heading>
1342 Source packages should specify the most recent version number
1343 of this policy document with which your package complied
1344 when it was last updated.
1348 This information may be used to file bug reports
1349 automatically if your package becomes too much out of date.
1353 The version is specified in the <tt>Standards-Version</tt>
1355 The format of the <tt>Standards-Version</tt> field is
1356 described in <ref id="f-Standards-Version">.
1360 You should regularly, and especially if your package has
1361 become out of date, check for the newest Policy Manual
1362 available and update your package, if necessary. When your
1363 package complies with the new standards you should update the
1364 <tt>Standards-Version</tt> source package field and
1365 release it.<footnote>
1366 See the file <file>upgrading-checklist</file> for
1367 information about policy which has changed between
1368 different versions of this document.
1374 <sect id="pkg-relations">
1375 <heading>Package relationships</heading>
1378 Source packages should specify which binary packages they
1379 require to be installed or not to be installed in order to
1380 build correctly. For example, if building a package
1381 requires a certain compiler, then the compiler should be
1382 specified as a build-time dependency.
1386 It is not necessary to explicitly specify build-time
1387 relationships on a minimal set of packages that are always
1388 needed to compile, link and put in a Debian package a
1389 standard "Hello World!" program written in C or C++. The
1390 required packages are called <em>build-essential</em>, and
1391 an informational list can be found in
1392 <file>/usr/share/doc/build-essential/list</file> (which is
1393 contained in the <tt>build-essential</tt>
1396 <list compact="compact">
1398 This allows maintaining the list separately
1399 from the policy documents (the list does not
1400 need the kind of control that the policy
1404 Having a separate package allows one to install
1405 the build-essential packages on a machine, as
1406 well as allowing other packages such as tasks to
1407 require installation of the build-essential
1408 packages using the depends relation.
1411 The separate package allows bug reports against
1412 the list to be categorized separately from
1413 the policy management process in the BTS.
1420 When specifying the set of build-time dependencies, one
1421 should list only those packages explicitly required by the
1422 build. It is not necessary to list packages which are
1423 required merely because some other package in the list of
1424 build-time dependencies depends on them.<footnote>
1425 The reason for this is that dependencies change, and
1426 you should list all those packages, and <em>only</em>
1427 those packages that <em>you</em> need directly. What
1428 others need is their business. For example, if you
1429 only link against <file>libimlib</file>, you will need to
1430 build-depend on <package>libimlib2-dev</package> but
1431 not against any <tt>libjpeg*</tt> packages, even
1432 though <tt>libimlib2-dev</tt> currently depends on
1433 them: installation of <package>libimlib2-dev</package>
1434 will automatically ensure that all of its run-time
1435 dependencies are satisfied.
1440 If build-time dependencies are specified, it must be
1441 possible to build the package and produce working binaries
1442 on a system with only essential and build-essential
1443 packages installed and also those required to satisfy the
1444 build-time relationships (including any implied
1445 relationships). In particular, this means that version
1446 clauses should be used rigorously in build-time
1447 relationships so that one cannot produce bad or
1448 inconsistently configured packages when the relationships
1449 are properly satisfied.
1453 <ref id="relationships"> explains the technical details.
1458 <heading>Changes to the upstream sources</heading>
1461 If changes to the source code are made that are not
1462 specific to the needs of the Debian system, they should be
1463 sent to the upstream authors in whatever form they prefer
1464 so as to be included in the upstream version of the
1469 If you need to configure the package differently for
1470 Debian or for Linux, and the upstream source doesn't
1471 provide a way to do so, you should add such configuration
1472 facilities (for example, a new <prgn>autoconf</prgn> test
1473 or <tt>#define</tt>) and send the patch to the upstream
1474 authors, with the default set to the way they originally
1475 had it. You can then easily override the default in your
1476 <file>debian/rules</file> or wherever is appropriate.
1480 You should make sure that the <prgn>configure</prgn> utility
1481 detects the correct architecture specification string
1482 (refer to <ref id="arch-spec"> for details).
1486 If you need to edit a <prgn>Makefile</prgn> where
1487 GNU-style <prgn>configure</prgn> scripts are used, you
1488 should edit the <file>.in</file> files rather than editing the
1489 <prgn>Makefile</prgn> directly. This allows the user to
1490 reconfigure the package if necessary. You should
1491 <em>not</em> configure the package and edit the generated
1492 <prgn>Makefile</prgn>! This makes it impossible for
1493 someone else to later reconfigure the package.
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>. This includes modifications
1505 made in the Debian package compared to the upstream one
1506 as well as other changes and updates to the package.
1508 Although there is nothing stopping an author who is also
1509 the Debian maintainer from using this changelog for all
1510 their changes, it will have to be renamed if the Debian
1511 and upstream maintainers become different people. In such
1512 a case, however, it might be better to maintain the package
1513 as a non-native package.
1518 Mistakes in changelogs are usually best rectified by making
1519 a new changelog entry rather than "rewriting history" by
1520 editing old changelog entries.
1524 The format of the <file>debian/changelog</file> allows the
1525 package building tools to discover which version of the package
1526 is being built and find out other release-specific information.
1530 That format is a series of entries like this:
1532 <example compact="compact">
1533 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1535 [optional blank line(s), stripped]
1537 * <var>change details</var>
1538 <var>more change details</var>
1540 [blank line(s), included in output of dpkg-parsechangelog]
1542 * <var>even more change details</var>
1544 [optional blank line(s), stripped]
1546 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1551 <var>package</var> and <var>version</var> are the source
1552 package name and version number.
1556 <var>distribution(s)</var> lists the distributions where
1557 this version should be installed when it is uploaded - it
1558 is copied to the <tt>Distribution</tt> field in the
1559 <file>.changes</file> file. See <ref id="f-Distribution">.
1563 <var>urgency</var> is the value for the <tt>Urgency</tt>
1564 field in the <file>.changes</file> file for the upload
1565 (see <ref id="f-Urgency">). It is not possible to specify
1566 an urgency containing commas; commas are used to separate
1567 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1568 <prgn>dpkg</prgn> changelog format (though there is
1569 currently only one useful <var>keyword</var>,
1570 <tt>urgency</tt>).<footnote>
1571 Recognised urgency values are <tt>low</tt>,
1572 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1573 They have an effect on how quickly a package will be
1574 considered for inclusion into the <tt>testing</tt>
1575 distribution, and give an indication of the importance
1576 of any fixes included in this upload.
1581 The change details may in fact be any series of lines
1582 starting with at least two spaces, but conventionally each
1583 change starts with an asterisk and a separating space and
1584 continuation lines are indented so as to bring them in
1585 line with the start of the text above. Blank lines may be
1586 used here to separate groups of changes, if desired.
1590 If this upload resolves bugs recorded in the Bug Tracking
1591 System (BTS), they may be automatically closed on the
1592 inclusion of this package into the Debian archive by
1593 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1594 in the change details.<footnote>
1595 To be precise, the string should match the following
1596 Perl regular expression:
1598 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1600 Then all of the bug numbers listed will be closed by the
1601 archive maintenance script (<prgn>katie</prgn>), or in
1602 the case of an NMU, marked as fixed.
1604 This information is conveyed via the <tt>Closes</tt> field
1605 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1609 The maintainer name and email address used in the changelog
1610 should be the details of the person uploading <em>this</em>
1611 version. They are <em>not</em> necessarily those of the
1612 usual package maintainer. The information here will be
1613 copied to the <tt>Changed-By</tt> field in the
1614 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1615 and then later used to send an acknowledgement when the
1616 upload has been installed.
1620 The <var>date</var> should be in RFC822 format<footnote>
1621 This is generated by the <prgn>822-date</prgn>
1623 </footnote>; it should include the time zone specified
1624 numerically, with the time zone name or abbreviation
1625 optionally present as a comment in parentheses.
1629 The first "title" line with the package name should start
1630 at the left hand margin; the "trailer" line with the
1631 maintainer and date details should be preceded by exactly
1632 one space. The maintainer details and the date must be
1633 separated by exactly two spaces.
1637 For more information on placement of the changelog files
1638 within binary packages, please see <ref id="changelogs">.
1641 <sect1><heading>Alternative changelog formats</heading>
1644 In non-experimental packages you must use a format for
1645 <file>debian/changelog</file> which is supported by the most
1646 recent released version of <prgn>dpkg</prgn>.
1650 It is possible to use a format different from the standard
1651 one by providing a changelog parser for the format you wish
1652 to use. The parser must have an API compatible with that
1653 expected by <prgn>dpkg-genchanges</prgn> and
1654 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1657 If there is general interest in the new format, you should
1658 contact the <package>dpkg</package> maintainer to have the
1659 parser script for it included in the <prgn>dpkg</prgn>
1660 package. (You will need to agree that the parser and its
1661 manpage may be distributed under the GNU GPL, just as the rest
1662 of <prgn>dpkg</prgn> is.)
1669 <heading>Error trapping in makefiles</heading>
1672 When <prgn>make</prgn> invokes a command in a makefile
1673 (including your package's upstream makefiles and
1674 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1675 means that <prgn>sh</prgn>'s usual bad error handling
1676 properties apply: if you include a miniature script as one
1677 of the commands in your makefile you'll find that if you
1678 don't do anything about it then errors are not detected
1679 and <prgn>make</prgn> will blithely continue after
1684 Every time you put more than one shell command (this
1685 includes using a loop) in a makefile command you
1686 must make sure that errors are trapped. For
1687 simple compound commands, such as changing directory and
1688 then running a program, using <tt>&&</tt> rather
1689 than semicolon as a command separator is sufficient. For
1690 more complex commands including most loops and
1691 conditionals you should include a separate <tt>set -e</tt>
1692 command at the start of every makefile command that's
1693 actually one of these miniature shell scripts.
1697 <sect id="timestamps">
1698 <heading>Time Stamps</heading>
1700 Maintainers should preserve the modification times of the
1701 upstream source files in a package, as far as is reasonably
1703 The rationale is that there is some information conveyed
1704 by knowing the age of the file, for example, you could
1705 recognize that some documentation is very old by looking
1706 at the modification time, so it would be nice if the
1707 modification time of the upstream source would be
1713 <sect id="restrictions">
1714 <heading>Restrictions on objects in source packages</heading>
1717 The source package may not contain any hard links<footnote>
1719 This is not currently detected when building source
1720 packages, but only when extracting
1724 Hard links may be permitted at some point in the
1725 future, but would require a fair amount of
1728 </footnote>, device special files, sockets or setuid or
1729 setgid files.<footnote>
1730 Setgid directories are allowed.
1735 <sect id="debianrules">
1736 <heading>Main building script: <file>debian/rules</file></heading>
1739 This file must be an executable makefile, and contains the
1740 package-specific recipes for compiling the package and
1741 building binary package(s) from the source.
1745 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1746 so that it can be invoked by saying its name rather than
1747 invoking <prgn>make</prgn> explicitly.
1751 Since an interactive <file>debian/rules</file> script makes it
1752 impossible to auto-compile that package and also makes it
1753 hard for other people to reproduce the same binary
1754 package, all <em>required targets</em> MUST be
1755 non-interactive. At a minimum, required targets are the
1756 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1757 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1758 <em>binary-indep</em>, and <em>build</em>. It also follows
1759 that any target that these targets depend on must also be
1764 The targets are as follows (required unless stated otherwise):
1766 <tag><tt>build</tt></tag>
1769 The <tt>build</tt> target should perform all the
1770 configuration and compilation of the package.
1771 If a package has an interactive pre-build
1772 configuration routine, the Debianized source package
1773 must either be built after this has taken place (so
1774 that the binary package can be built without rerunning
1775 the configuration) or the configuration routine
1776 modified to become non-interactive. (The latter is
1777 preferable if there are architecture-specific features
1778 detected by the configuration routine.)
1782 For some packages, notably ones where the same
1783 source tree is compiled in different ways to produce
1784 two binary packages, the <tt>build</tt> target
1785 does not make much sense. For these packages it is
1786 good enough to provide two (or more) targets
1787 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1788 for each of the ways of building the package, and a
1789 <tt>build</tt> target that does nothing. The
1790 <tt>binary</tt> target will have to build the
1791 package in each of the possible ways and make the
1792 binary package out of each.
1796 The <tt>build</tt> target must not do anything
1797 that might require root privilege.
1801 The <tt>build</tt> target may need to run the
1802 <tt>clean</tt> target first - see below.
1806 When a package has a configuration and build routine
1807 which takes a long time, or when the makefiles are
1808 poorly designed, or when <tt>build</tt> needs to
1809 run <tt>clean</tt> first, it is a good idea to
1810 <tt>touch build</tt> when the build process is
1811 complete. This will ensure that if <tt>debian/rules
1812 build</tt> is run again it will not rebuild the whole
1814 Another common way to do this is for <tt>build</tt>
1815 to depend on <prgn>build-stamp</prgn> and to do
1816 nothing else, and for the <prgn>build-stamp</prgn>
1817 target to do the building and to <tt>touch
1818 build-stamp</tt> on completion. This is
1819 especially useful if the build routine creates a
1820 file or directory called <tt>build</tt>; in such a
1821 case, <tt>build</tt> will need to be listed as
1822 a phony target (i.e., as a dependency of the
1823 <tt>.PHONY</tt> target). See the documentation of
1824 <prgn>make</prgn> for more information on phony
1830 <tag><tt>build-arch</tt> (optional),
1831 <tt>build-indep</tt> (optional)
1835 A package may also provide both of the targets
1836 <tt>build-arch</tt> and <tt>build-indep</tt>.
1837 The <tt>build-arch</tt> target, if provided, should
1838 perform all the configuration and compilation required
1839 for producing all architecture-dependant binary packages
1840 (those packages for which the body of the
1841 <tt>Architecture</tt> field in <tt>debian/control</tt>
1842 is not <tt>all</tt>).
1843 Similarly, the <tt>build-indep</tt> target, if
1844 provided, should perform all the configuration and
1845 compilation required for producing all
1846 architecture-independent binary packages
1847 (those packages for which the body of the
1848 <tt>Architecture</tt> field in <tt>debian/control</tt>
1850 The <tt>build</tt> target should depend on those of the
1851 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1852 are provided in the rules file.
1856 If one or both of the targets <tt>build-arch</tt> and
1857 <tt>build-indep</tt> are not provided, then invoking
1858 <file>debian/rules</file> with one of the not-provided
1859 targets as arguments should produce a exit status code
1860 of 2. Usually this is provided automatically by make
1861 if the target is missing.
1865 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1866 must not do anything that might require root privilege.
1870 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1871 <tt>binary-indep</tt>
1875 The <tt>binary</tt> target must be all that is
1876 necessary for the user to build the binary package(s)
1877 produced from this source package. It is
1878 split into two parts: <prgn>binary-arch</prgn> builds
1879 the binary packages which are specific to a particular
1880 architecture, and <tt>binary-indep</tt> builds
1881 those which are not.
1884 <tt>binary</tt> may be (and commonly is) a target with
1885 no commands which simply depends on
1886 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1889 Both <tt>binary-*</tt> targets should depend on the
1890 <tt>build</tt> target, or on the appropriate
1891 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1892 provided, so that the package is built if it has not
1893 been already. It should then create the relevant
1894 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1895 make their control files and <prgn>dpkg-deb</prgn> to
1896 build them and place them in the parent of the top
1901 Both the <tt>binary-arch</tt> and
1902 <tt>binary-indep</tt> targets <em>must</em> exist.
1903 If one of them has nothing to do (which will always be
1904 the case if the source generates only a single binary
1905 package, whether architecture-dependent or not), it
1906 must still exist and must always succeed.
1910 The <tt>binary</tt> targets must be invoked as
1912 The <prgn>fakeroot</prgn> package often allows one
1913 to build a package correctly even without being
1919 <tag><tt>clean</tt></tag>
1922 This must undo any effects that the <tt>build</tt>
1923 and <tt>binary</tt> targets may have had, except
1924 that it should leave alone any output files created in
1925 the parent directory by a run of a <tt>binary</tt>
1930 If a <tt>build</tt> file is touched at the end of
1931 the <tt>build</tt> target, as suggested above, it
1932 should be removed as the first action that
1933 <tt>clean</tt> performs, so that running
1934 <tt>build</tt> again after an interrupted
1935 <tt>clean</tt> doesn't think that everything is
1940 The <tt>clean</tt> target may need to be
1941 invoked as root if <tt>binary</tt> has been
1942 invoked since the last <tt>clean</tt>, or if
1943 <tt>build</tt> has been invoked as root (since
1944 <tt>build</tt> may create directories, for
1949 <tag><tt>get-orig-source</tt> (optional)</tag>
1952 This target fetches the most recent version of the
1953 original source package from a canonical archive site
1954 (via FTP or WWW, for example), does any necessary
1955 rearrangement to turn it into the original source
1956 tar file format described below, and leaves it in the
1961 This target may be invoked in any directory, and
1962 should take care to clean up any temporary files it
1967 This target is optional, but providing it if
1968 possible is a good idea.
1974 The <tt>build</tt>, <tt>binary</tt> and
1975 <tt>clean</tt> targets must be invoked with the current
1976 directory being the package's top-level directory.
1981 Additional targets may exist in <file>debian/rules</file>,
1982 either as published or undocumented interfaces or for the
1983 package's internal use.
1987 The architectures we build on and build for are determined
1988 by <prgn>make</prgn> variables using the utility
1989 <qref id="pkg-dpkgarch"><prgn>dpkg-architecture</prgn></qref>.
1990 You can determine the
1991 Debian architecture and the GNU style architecture
1992 specification string for the build machine (the machine type
1993 we are building on) as well as for the host machine (the
1994 machine type we are building for). Here is a list of
1995 supported <prgn>make</prgn> variables:
1996 <list compact="compact">
1998 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2001 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2002 specification string)
2005 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2006 <tt>DEB_*_GNU_TYPE</tt>)
2009 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2010 <tt>DEB_*_GNU_TYPE</tt>)
2012 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2013 the build machine or <tt>HOST</tt> for specification of the
2018 Backward compatibility can be provided in the rules file
2019 by setting the needed variables to suitable default
2020 values; please refer to the documentation of
2021 <prgn>dpkg-architecture</prgn> for details.
2025 It is important to understand that the <tt>DEB_*_ARCH</tt>
2026 string only determines which Debian architecture we are
2027 building on or for. It should not be used to get the CPU
2028 or system information; the GNU style variables should be
2033 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2034 <sect id="substvars">
2035 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2038 When <prgn>dpkg-gencontrol</prgn>,
2039 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2040 generate control files they perform variable substitutions
2041 on their output just before writing it. Variable
2042 substitutions have the form <tt>${<var>variable</var>}</tt>.
2043 The optional file <file>debian/substvars</file> contains
2044 variable substitutions to be used; variables can also be set
2045 directly from <file>debian/rules</file> using the <tt>-V</tt>
2046 option to the source packaging commands, and certain
2047 predefined variables are also available.
2051 The <file>debian/substvars</file> file is usually generated and
2052 modified dynamically by <file>debian/rules</file> targets, in
2053 which case it must be removed by the <tt>clean</tt> target.
2057 See <manref name="dpkg-source" section="1"> for full
2058 details about source variable substitutions, including the
2059 format of <file>debian/substvars</file>.</p>
2062 <sect id="debianfiles">
2063 <heading>Generated files list: <file>debian/files</file></heading>
2066 This file is not a permanent part of the source tree; it
2067 is used while building packages to record which files are
2068 being generated. <prgn>dpkg-genchanges</prgn> uses it
2069 when it generates a <file>.changes</file> file.
2073 It should not exist in a shipped source package, and so it
2074 (and any backup files or temporary files such as
2075 <file>files.new</file><footnote>
2076 <file>files.new</file> is used as a temporary file by
2077 <prgn>dpkg-gencontrol</prgn> and
2078 <prgn>dpkg-distaddfile</prgn> - they write a new
2079 version of <tt>files</tt> here before renaming it,
2080 to avoid leaving a corrupted copy if an error
2082 </footnote>) should be removed by the
2083 <tt>clean</tt> target. It may also be wise to
2084 ensure a fresh start by emptying or removing it at the
2085 start of the <tt>binary</tt> target.
2089 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2090 package, it adds an entry to <file>debian/files</file> for the
2091 <file>.deb</file> file that will be created when <tt>dpkg-deb
2092 --build</tt> is run for that binary package. So for most
2093 packages all that needs to be done with this file is to
2094 delete it in the <tt>clean</tt> target.
2098 If a package upload includes files besides the source
2099 package and any binary packages whose control files were
2100 made with <prgn>dpkg-gencontrol</prgn> then they should be
2101 placed in the parent of the package's top-level directory
2102 and <prgn>dpkg-distaddfile</prgn> should be called to add
2103 the file to the list in <file>debian/files</file>.</p>
2109 <chapt id="controlfields">
2110 <heading>Control files and their fields</heading>
2113 The package management system manipulates data represented in
2114 a common format, known as <em>control data</em>, stored in
2115 <em>control files</em>.
2116 Control files are used for source packages, binary packages and
2117 the <file>.changes</file> files which control the installation
2118 of uploaded files<footnote>
2119 <prgn>dpkg</prgn>'s internal databases are in a similar
2124 <sect id="controlsyntax">
2125 <heading>Syntax of control files</heading>
2128 A control file consists of one or more paragraphs of
2130 The paragraphs are also sometimes referred to as stanzas.
2132 The paragraphs are separated by blank lines. Some control
2133 files allow only one paragraph; others allow several, in
2134 which case each paragraph usually refers to a different
2135 package. (For example, in source packages, the first
2136 paragraph refers to the source package, and later paragraphs
2137 refer to binary packages generated from the source.)
2141 Each paragraph consists of a series of data fields; each
2142 field consists of the field name, followed by a colon and
2143 then the data/value associated with that field. It ends at
2144 the end of the line. Horizontal whitespace (spaces and
2145 tabs) may occur immediately before or after the value and is
2146 ignored there; it is conventional to put a single space
2147 after the colon. For example, a field might be:
2148 <example compact="compact">
2151 the field name is <tt>Package</tt> and the field value
2156 Some fields' values may span several lines; in this case
2157 each continuation line must start with a space or a tab.
2158 Any trailing spaces or tabs at the end of individual
2159 lines of a field value are ignored.
2163 Except where otherwise stated, only a single line of data is
2164 allowed and whitespace is not significant in a field body.
2165 Whitespace must not appear inside names (of packages,
2166 architectures, files or anything else) or version numbers,
2167 or between the characters of multi-character version
2172 Field names are not case-sensitive, but it is usual to
2173 capitalize the field names using mixed case as shown below.
2177 Blank lines, or lines consisting only of spaces and tabs,
2178 are not allowed within field values or between fields - that
2179 would mean a new paragraph.
2184 <sect id="sourcecontrolfiles">
2185 <heading>Source package control files -- <file>debian/control</file></heading>
2188 The <file>debian/control</file> file contains the most vital
2189 (and version-independent) information about the source package
2190 and about the binary packages it creates.
2194 The first paragraph of the control file contains information about
2195 the source package in general. The subsequent sets each describe a
2196 binary package that the source tree builds.
2200 The fields in the general paragraph (the first one, for the source
2203 <list compact="compact">
2204 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2205 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2206 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2207 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2208 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2209 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2214 The fields in the binary package paragraphs are:
2216 <list compact="compact">
2217 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2218 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2219 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2220 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2221 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2222 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2223 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2228 The syntax and semantics of the fields are described below.
2234 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2235 generate control files for binary packages (see below), by
2236 <prgn>dpkg-genchanges</prgn> to generate the
2237 <tt>.changes</tt> file to accompany the upload, and by
2238 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2239 source control file as part of a source archive.
2243 The fields here may contain variable references - their
2244 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2245 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2246 when they generate output control files.
2247 See <ref id="substvars"> for details.
2252 <sect id="binarycontrolfiles">
2253 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2256 The <file>DEBIAN/control</file> file contains the most vital
2257 (and version-dependent) information about a binary package.
2261 The fields in this file are:
2263 <list compact="compact">
2264 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2265 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2266 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2267 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2268 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2269 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2271 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2272 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2273 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2274 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2279 <sect id="debiansourcecontrolfiles">
2280 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2283 This file contains a series of fields, identified and
2284 separated just like the fields in the control file of
2285 a binary package. The fields are listed below; their
2286 syntax is described above, in <ref id="pkg-controlfields">.
2288 <list compact="compact">
2289 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2290 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2291 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2292 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2293 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2294 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2295 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2296 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2301 The source package control file is generated by
2302 <prgn>dpkg-source</prgn> when it builds the source
2303 archive, from other files in the source package,
2304 described above. When unpacking, it is checked against
2305 the files and directories in the other parts of the
2311 <sect id="debianchangesfiles">
2312 <heading>Debian changes files -- <file>.changes</file></heading>
2315 The .changes files are used by the Debian archive maintenance
2316 software to process updates to packages. They contain one
2317 paragraph which contains information from the
2318 <tt>debian/control</tt> file and other data about the
2319 source package gathered via <tt>debian/changelog</tt>
2320 and <tt>debian/rules</tt>.
2324 The fields in this file are:
2326 <list compact="compact">
2327 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2328 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2329 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2330 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2331 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2333 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2335 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2337 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2339 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2340 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2345 <sect id="controlfieldslist">
2346 <heading>List of fields</heading>
2348 <sect1 id="f-Source">
2349 <heading><tt>Source</tt></heading>
2352 This field identifies the source package name.
2356 In a main source control information, a <file>.changes</file>
2357 or a <file>.dsc</file> file this may contain only the name
2358 of the source package.
2362 In the control file of a binary package it may be followed
2363 by a version number in parentheses<footnote>
2364 It is customary to leave a space after the package name
2365 if a version number is specified.
2367 This version number may be omitted (and is, by
2368 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2369 the <tt>Version</tt> field of the binary package in
2370 question. The field itself may be omitted from a binary
2371 package control file when the source package has the same
2372 name and version as the binary package.
2376 <sect1 id="f-Maintainer">
2377 <heading><tt>Maintainer</tt></heading>
2380 The package maintainer's name and email address. The name
2381 should come first, then the email address inside angle
2382 brackets <tt><></tt> (in RFC822 format).
2386 If the maintainer's name contains a full stop then the
2387 whole field will not work directly as an email address due
2388 to a misfeature in the syntax specified in RFC822; a
2389 program using this field as an address must check for this
2390 and correct the problem if necessary (for example by
2391 putting the name in round brackets and moving it to the
2392 end, and bringing the email address forward).
2396 <sect1 id="f-Changed-By">
2397 <heading><tt>Changed-By</tt></heading>
2400 The name and email address of the person who changed the
2401 said package. Usually the name of the maintainer.
2402 All the rules for the Maintainer field apply here, too.
2406 <sect1 id="f-Section">
2407 <heading><tt>Section</tt></heading>
2410 This field specifies an application area into which the package
2411 has been classified. See <ref id="subsections">.
2415 When it appears in the <file>debian/control</file> file,
2416 it gives the value for the subfield of the same name in
2417 the <tt>Files</tt> field of the <file>.changes</file> file.
2418 It also gives the default for the same field in the binary
2423 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2424 field in the control file of a binary package - use the
2425 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2429 <sect1 id="f-Priority">
2430 <heading><tt>Priority</tt></heading>
2433 This field represents how important that it is that the user
2434 have the package installed. See <ref id="priorities">.
2438 When it appears in the <file>debian/control</file> file,
2439 it gives the value for the subfield of the same name in
2440 the <tt>Files</tt> field of the <file>.changes</file> file.
2441 It also gives the default for the same field in the binary
2446 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2447 field in the control file of a binary package - use the
2448 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2452 <sect1 id="f-Package">
2453 <heading><tt>Package</tt></heading>
2456 The name of the binary package.
2460 Package names must consist only of lower case letters
2461 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2462 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2463 They must be at least two characters long and must start
2464 with an alphanumeric character.
2468 <sect1 id="f-Architecture">
2469 <heading><tt>Architecture</tt></heading>
2472 This is the architecture string; it is a single word for
2473 the Debian architecture. The special value <tt>all</tt>
2474 indicates that the package is architecture-independent.
2478 In the main <file>debian/control</file> file in the source
2479 package, or in the source package control file
2480 <file>.dsc</file>, a list of architectures (separated by
2481 spaces) is also allowed, as is the special value
2482 <tt>any</tt>. A list indicates that the source will build
2483 an architecture-dependent package, and will only work
2484 correctly on the listed architectures. <tt>any</tt>
2485 indicates that though the source package isn't dependent
2486 on any particular architecture and should compile fine on
2487 any one, the binary package(s) produced are not
2488 architecture-independent but will instead be specific to
2489 whatever the current build architecture is.
2493 In a <file>.changes</file> file the <tt>Architecture</tt>
2494 field lists the architecture(s) of the package(s)
2495 currently being uploaded. This will be a list; if the
2496 source for the package is being uploaded too the special
2497 entry <tt>source</tt> is also present.
2501 See <ref id="debianrules"> for information how to get the
2502 architecture for the build process.
2506 <sect1 id="f-Essential">
2507 <heading><tt>Essential</tt></heading>
2510 This is a boolean field which may occur only in the
2511 control file of a binary package or in a per-package fields
2512 paragraph of a main source control data file.
2516 If set to <tt>yes</tt> then the package management system
2517 will refuse to remove the package (upgrading and replacing
2518 it is still possible). The other possible value is <tt>no</tt>,
2519 which is the same as not having the field at all.
2524 <heading>Package interrelationship fields:
2525 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2526 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2527 <tt>Provides</tt>, <tt>Replaces</tt>
2531 These fields describe the package's relationships with
2532 other packages. Their syntax and semantics are described
2533 in <ref id="relationships">.</p>
2536 <sect1 id="f-Standards-Version">
2537 <heading><tt>Standards-Version</tt></heading>
2540 The most recent version of the standards (the policy
2541 manual and associated texts) with which the package
2546 The version number has four components: major and minor
2547 version number and major and minor patch level. When the
2548 standards change in a way that requires every package to
2549 change the major number will be changed. Significant
2550 changes that will require work in many packages will be
2551 signaled by a change to the minor number. The major patch
2552 level will be changed for any change to the meaning of the
2553 standards, however small; the minor patch level will be
2554 changed when only cosmetic, typographical or other edits
2555 are made which neither change the meaning of the document
2556 nor affect the contents of packages.
2560 Thus only the first three components of the policy version
2561 are significant in the <em>Standards-Version</em> control
2562 field, and so either these three components or the all
2563 four components may be specified.<footnote>
2564 In the past, people specified the full version number
2565 in the Standards-Version field, for example "2.3.0.0".
2566 Since minor patch-level changes don't introduce new
2567 policy, it was thought it would be better to relax
2568 policy and only require the first 3 components to be
2569 specified, in this example "2.3.0". All four
2570 components may still be used if someone wishes to do so.
2576 <sect1 id="f-Version">
2577 <heading><tt>Version</tt></heading>
2580 The version number of a package. The format is:
2581 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2585 The three components here are:
2587 <tag><var>epoch</var></tag>
2590 This is a single (generally small) unsigned integer. It
2591 may be omitted, in which case zero is assumed. If it is
2592 omitted then the <var>upstream_version</var> may not
2597 It is provided to allow mistakes in the version numbers
2598 of older versions of a package, and also a package's
2599 previous version numbering schemes, to be left behind.
2603 <tag><var>upstream_version</var></tag>
2606 This is the main part of the version number. It is
2607 usually the version number of the original ("upstream")
2608 package from which the <file>.deb</file> file has been made,
2609 if this is applicable. Usually this will be in the same
2610 format as that specified by the upstream author(s);
2611 however, it may need to be reformatted to fit into the
2612 package management system's format and comparison
2617 The comparison behavior of the package management system
2618 with respect to the <var>upstream_version</var> is
2619 described below. The <var>upstream_version</var>
2620 portion of the version number is mandatory.
2624 The <var>upstream_version</var> may contain only
2625 alphanumerics<footnote>
2626 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2628 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2629 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2630 start with a digit. If there is no
2631 <var>debian_revision</var> then hyphens are not allowed;
2632 if there is no <var>epoch</var> then colons are not
2637 <tag><var>debian_revision</var></tag>
2640 This part of the version number specifies the version of
2641 the Debian package based on the upstream version. It
2642 may contain only alphanumerics and the characters
2643 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2644 compared in the same way as the
2645 <var>upstream_version</var> is.
2649 It is optional; if it isn't present then the
2650 <var>upstream_version</var> may not contain a hyphen.
2651 This format represents the case where a piece of
2652 software was written specifically to be turned into a
2653 Debian package, and so there is only one "debianization"
2654 of it and therefore no revision indication is required.
2658 It is conventional to restart the
2659 <var>debian_revision</var> at <tt>1</tt> each time the
2660 <var>upstream_version</var> is increased.
2664 The package management system will break the version
2665 number apart at the last hyphen in the string (if there
2666 is one) to determine the <var>upstream_version</var> and
2667 <var>debian_revision</var>. The absence of a
2668 <var>debian_revision</var> compares earlier than the
2669 presence of one (but note that the
2670 <var>debian_revision</var> is the least significant part
2671 of the version number).
2678 The <var>upstream_version</var> and <var>debian_revision</var>
2679 parts are compared by the package management system using the
2684 The strings are compared from left to right.
2688 First the initial part of each string consisting entirely of
2689 non-digit characters is determined. These two parts (one of
2690 which may be empty) are compared lexically. If a difference
2691 is found it is returned. The lexical comparison is a
2692 comparison of ASCII values modified so that all the letters
2693 sort earlier than all the non-letters.
2697 Then the initial part of the remainder of each string which
2698 consists entirely of digit characters is determined. The
2699 numerical values of these two parts are compared, and any
2700 difference found is returned as the result of the comparison.
2701 For these purposes an empty string (which can only occur at
2702 the end of one or both version strings being compared) counts
2707 These two steps (comparing and removing initial non-digit
2708 strings and initial digit strings) are repeated until a
2709 difference is found or both strings are exhausted.
2713 Note that the purpose of epochs is to allow us to leave behind
2714 mistakes in version numbering, and to cope with situations
2715 where the version numbering scheme changes. It is
2716 <em>not</em> intended to cope with version numbers containing
2717 strings of letters which the package management system cannot
2718 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2719 silly orderings (the author of this manual has heard of a
2720 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2721 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2722 <tt>2</tt> and so forth).
2726 <sect1 id="f-Description">
2727 <heading><tt>Description</tt></heading>
2730 In a source or binary control file, the <tt>Description</tt>
2731 field contains a description of the binary package, consisting
2732 of two parts, the synopsis or the short description, and the
2733 long description. The field's format is as follows:
2738 Description: <single line synopsis>
2739 <extended description over several lines>
2744 The lines in the extended description can have these formats:
2750 Those starting with a single space are part of a paragraph.
2751 Successive lines of this form will be word-wrapped when
2752 displayed. The leading space will usually be stripped off.
2756 Those starting with two or more spaces. These will be
2757 displayed verbatim. If the display cannot be panned
2758 horizontally, the displaying program will linewrap them "hard"
2759 (i.e., without taking account of word breaks). If it can they
2760 will be allowed to trail off to the right. None, one or two
2761 initial spaces may be deleted, but the number of spaces
2762 deleted from each line will be the same (so that you can have
2763 indenting work correctly, for example).
2767 Those containing a single space followed by a single full stop
2768 character. These are rendered as blank lines. This is the
2769 <em>only</em> way to get a blank line<footnote>
2770 Completely empty lines will not be rendered as blank lines.
2771 Instead, they will cause the parser to think you're starting
2772 a whole new record in the control file, and will therefore
2773 likely abort with an error.
2778 Those containing a space, a full stop and some more characters.
2779 These are for future expansion. Do not use them.
2785 Do not use tab characters. Their effect is not predictable.
2789 See <ref id="descriptions"> for further information on this.
2793 In a <file>.changes</file> file, the <tt>Description</tt> field
2794 contains a summary of the descriptions for the packages being
2799 The part of the field before the first newline is empty;
2800 thereafter each line has the name of a binary package and
2801 the summary description line from that binary package.
2802 Each line is indented by one space.
2807 <sect1 id="f-Distribution">
2808 <heading><tt>Distribution</tt></heading>
2811 In a <file>.changes</file> file or parsed changelog output
2812 this contains the (space-separated) name(s) of the
2813 distribution(s) where this version of the package should
2814 be installed. Valid distributions are determined by the
2815 archive maintainers.<footnote>
2816 Current distribution names are:
2817 <taglist compact="compact">
2818 <tag><em>stable</em></tag>
2820 This is the current "released" version of Debian
2821 GNU/Linux. Once the distribution is
2822 <em>stable</em> only security fixes and other
2823 major bug fixes are allowed. When changes are
2824 made to this distribution, the release number is
2825 increased (for example: 2.2r1 becomes 2.2r2 then
2829 <tag><em>unstable</em></tag>
2831 This distribution value refers to the
2832 <em>developmental</em> part of the Debian
2833 distribution tree. New packages, new upstream
2834 versions of packages and bug fixes go into the
2835 <em>unstable</em> directory tree. Download from
2836 this distribution at your own risk.
2839 <tag><em>testing</em></tag>
2841 This distribution value refers to the
2842 <em>testing</em> part of the Debian distribution
2843 tree. It receives its packages from the
2844 unstable distribution after a short time lag to
2845 ensure that there are no major issues with the
2846 unstable packages. It is less prone to breakage
2847 than unstable, but still risky. It is not
2848 possible to upload packages directly to
2852 <tag><em>frozen</em></tag>
2854 From time to time, the <em>testing</em>
2855 distribution enters a state of "code-freeze" in
2856 anticipation of release as a <em>stable</em>
2857 version. During this period of testing only
2858 fixes for existing or newly-discovered bugs will
2859 be allowed. The exact details of this stage are
2860 determined by the Release Manager.
2863 <tag><em>experimental</em></tag>
2865 The packages with this distribution value are
2866 deemed by their maintainers to be high
2867 risk. Oftentimes they represent early beta or
2868 developmental packages from various sources that
2869 the maintainers want people to try, but are not
2870 ready to be a part of the other parts of the
2871 Debian distribution tree. Download at your own
2877 You should list <em>all</em> distributions that the
2878 package should be installed into.
2882 More information is available in the Debian Developer's
2883 Reference, section "The Debian archive".
2890 <heading><tt>Date</tt></heading>
2893 This field includes the date the package was built or last edited.
2897 The value of this field is usually extracted from the
2898 <file>debian/changelog</file> file - see
2899 <ref id="dpkgchangelog">).
2903 <sect1 id="f-Format">
2904 <heading><tt>Format</tt></heading>
2907 This field specifies a format revision for the file.
2908 The most current format described in the Policy Manual
2909 is version <strong>1.5</strong>. The syntax of the
2910 format value is the same as that of a package version
2911 number except that no epoch or Debian revision is allowed
2912 - see <ref id="f-Version">.
2916 <sect1 id="f-Urgency">
2917 <heading><tt>Urgency</tt></heading>
2920 This is a description of how important it is to upgrade to
2921 this version from previous ones. It consists of a single
2922 keyword usually taking one of the values <tt>low</tt>,
2923 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2924 followed by an optional commentary (separated by a space)
2925 which is usually in parentheses. For example:
2928 Urgency: low (HIGH for users of diversions)
2934 The value of this field is usually extracted from the
2935 <file>debian/changelog</file> file - see
2936 <ref id="dpkgchangelog">.
2940 <sect1 id="f-Changes">
2941 <heading><tt>Changes</tt></heading>
2944 This field contains the human-readable changes data, describing
2945 the differences between the last version and the current one.
2949 There should be nothing in this field before the first
2950 newline; all the subsequent lines must be indented by at
2951 least one space; blank lines must be represented by a line
2952 consiting only of a space and a full stop.
2956 The value of this field is usually extracted from the
2957 <file>debian/changelog</file> file - see
2958 <ref id="dpkgchangelog">).
2962 Each version's change information should be preceded by a
2963 "title" line giving at least the version, distribution(s)
2964 and urgency, in a human-readable way.
2968 If data from several versions is being returned the entry
2969 for the most recent version should be returned first, and
2970 entries should be separated by the representation of a
2971 blank line (the "title" line may also be followed by the
2972 representation of blank line).
2976 <sect1 id="f-Binary">
2977 <heading><tt>Binary</tt></heading>
2980 This field is a list of binary packages.
2984 When it appears in the <file>.dsc</file> file it is the list
2985 of binary packages which a source package can produce. It
2986 does not necessarily produce all of these binary packages
2987 for every architecture. The source control file doesn't
2988 contain details of which architectures are appropriate for
2989 which of the binary packages.
2993 When it appears in a <file>.changes</file> file it lists the
2994 names of the binary packages actually being uploaded.
2998 The syntax is a list of binary packages separated by
3000 A space after each comma is conventional.
3001 </footnote>. Currently the packages must be separated using
3002 only spaces in the <file>.changes</file> file.
3006 <sect1 id="f-Installed-Size">
3007 <heading><tt>Installed-Size</tt></heading>
3010 This field appears in the control files of binary
3011 packages, and in the <file>Packages</file> files. It gives
3012 the total amount of disk space required to install the
3017 The disk space is represented in kilobytes as a simple
3022 <sect1 id="f-Files">
3023 <heading><tt>Files</tt></heading>
3026 This field contains a list of files with information about
3027 each one. The exact information and syntax varies with
3028 the context. In all cases the part of the field
3029 contents on the same line as the field name is empty. The
3030 remainder of the field is one line per file, each line
3031 being indented by one space and containing a number of
3032 sub-fields separated by spaces.
3036 In the <file>.dsc</file> file, each line contains the MD5
3037 checksum, size and filename of the tar file and (if applicable)
3038 diff file which make up the remainder of the source
3040 That is, the parts which are not the <tt>.dsc</tt>.
3042 The exact forms of the filenames are described
3043 in <ref id="pkg-sourcearchives">.
3047 In the <file>.changes</file> file this contains one line per
3048 file being uploaded. Each line contains the MD5 checksum,
3049 size, section and priority and the filename.
3050 The <qref id="f-Section">section</qref>
3051 and <qref id="f-Priority">priority</qref>
3052 are the values of the corresponding fields in
3053 the main source control file. If no section or priority is
3054 specified then <tt>-</tt> should be used, though section
3055 and priority values must be specified for new packages to
3056 be installed properly.
3060 The special value <tt>byhand</tt> for the section in a
3061 <tt>.changes</tt> file indicates that the file in question
3062 is not an ordinary package file and must by installed by
3063 hand by the distribution maintainers. If the section is
3064 <tt>byhand</tt> the priority should be <tt>-</tt>.
3068 If a new Debian revision of a package is being shipped and
3069 no new original source archive is being distributed the
3070 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3071 entry for the original source archive
3072 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3073 but the <file>.changes</file> file should leave it out. In
3074 this case the original source archive on the distribution
3075 site must match exactly, byte-for-byte, the original
3076 source archive which was used to generate the
3077 <file>.dsc</file> file and diff which are being uploaded.</p>
3080 <sect1 id="f-Closes">
3081 <heading><tt>Closes</tt></heading>
3084 A space-separated list of bug report numbers that the upload
3085 governed by the .changes file closes.
3092 <heading>User-defined fields</heading>
3095 Additional user-defined fields may be added to the
3096 source package control file. Such fields will be
3097 ignored, and not copied to (for example) binary or
3098 source package control files or upload control files.
3102 If you wish to add additional unsupported fields to
3103 these output files you should use the mechanism
3108 Fields in the main source control information file with
3109 names starting <tt>X</tt>, followed by one or more of
3110 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3111 be copied to the output files. Only the part of the
3112 field name after the hyphen will be used in the output
3113 file. Where the letter <tt>B</tt> is used the field
3114 will appear in binary package control files, where the
3115 letter <tt>S</tt> is used in source package control
3116 files and where <tt>C</tt> is used in upload control
3117 (<tt>.changes</tt>) files.
3121 For example, if the main source information control file
3124 XBS-Comment: I stand between the candle and the star.
3126 then the binary and source package control files will contain the
3129 Comment: I stand between the candle and the star.
3138 <chapt id="maintainerscripts">
3139 <heading>Package maintainer scripts and installation procedure</heading>
3142 <heading>Introduction to package maintainer scripts</heading>
3145 It is possible to supply scripts as part of a package which
3146 the package management system will run for you when your
3147 package is installed, upgraded or removed.
3151 These scripts are the files <prgn>preinst</prgn>,
3152 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3153 control area of the package. They must be proper executable
3154 files; if they are scripts (which is recommended), they must
3155 start with the usual <tt>#!</tt> convention. They should be
3156 readable and executable by anyone, and not world-writable.
3160 The package management system looks at the exit status from
3161 these scripts. It is important that they exit with a
3162 non-zero status if there is an error, so that the package
3163 management system can stop its processing. For shell
3164 scripts this means that you <em>almost always</em> need to
3165 use <tt>set -e</tt> (this is usually true when writing shell
3166 scripts, in fact). It is also important, of course, that
3167 they don't exit with a non-zero status if everything went
3172 When a package is upgraded a combination of the scripts from
3173 the old and new packages is called during the upgrade
3174 procedure. If your scripts are going to be at all
3175 complicated you need to be aware of this, and may need to
3176 check the arguments to your scripts.
3180 Broadly speaking the <prgn>preinst</prgn> is called before
3181 (a particular version of) a package is installed, and the
3182 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3183 before (a version of) a package is removed and the
3184 <prgn>postrm</prgn> afterwards.
3188 Programs called from maintainer scripts should not normally
3189 have a path prepended to them. Before installation is
3190 started, the package management system checks to see if the
3191 programs <prgn>ldconfig</prgn>,
3192 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3193 and <prgn>update-rc.d</prgn> can be found via the
3194 <tt>PATH</tt> environment variable. Those programs, and any
3195 other program that one would expect to be on the
3196 <tt>PATH</tt>, should thus be invoked without an absolute
3197 pathname. Maintainer scripts should also not reset the
3198 <tt>PATH</tt>, though they might choose to modify it by
3199 prepending or appending package-specific directories. These
3200 considerations really apply to all shell scripts.</p>
3203 <sect id="idempotency">
3204 <heading>Maintainer scripts Idempotency</heading>
3207 It is necessary for the error recovery procedures that the
3208 scripts be idempotent. This means that if it is run
3209 successfully, and then it is called again, it doesn't bomb
3210 out or cause any harm, but just ensures that everything is
3211 the way it ought to be. If the first call failed, or
3212 aborted half way through for some reason, the second call
3213 should merely do the things that were left undone the first
3214 time, if any, and exit with a success status if everything
3216 This is so that if an error occurs, the user interrupts
3217 <prgn>dpkg</prgn> or some other unforeseen circumstance
3218 happens you don't leave the user with a badly-broken
3219 package when <prgn>dpkg</prgn> attempts to repeat the
3225 <sect id="controllingterminal">
3226 <heading>Controlling terminal for maintainer scripts</heading>
3229 The maintainer scripts are guaranteed to run with a
3230 controlling terminal and can interact with the user.
3231 If they need to prompt for passwords, do full-screen
3232 interaction or something similar you should do these
3233 things to and from <file>/dev/tty</file>, since
3234 <prgn>dpkg</prgn> will at some point redirect scripts'
3235 standard input and output so that it can log the
3236 installation process. Likewise, because these scripts
3237 may be executed with standard output redirected into a
3238 pipe for logging purposes, Perl scripts should set
3239 unbuffered output by setting <tt>$|=1</tt> so that the
3240 output is printed immediately rather than being
3245 Each script should return a zero exit status for
3246 success, or a nonzero one for failure.
3250 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3255 <list compact="compact">
3257 <var>new-preinst</var> <tt>install</tt>
3260 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3263 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3266 <var>old-preinst</var> <tt>abort-upgrade</tt>
3267 <var>new-version</var>
3272 <list compact="compact">
3274 <var>postinst</var> <tt>configure</tt>
3275 <var>most-recently-configured-version</var>
3278 <var>old-postinst</var> <tt>abort-upgrade</tt>
3279 <var>new-version</var>
3282 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3283 <tt>in-favour</tt> <var>package</var>
3284 <var>new-version</var>
3287 <var>deconfigured's-postinst</var>
3288 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3289 <var>failed-install-package</var> <var>version</var>
3290 <tt>removing</tt> <var>conflicting-package</var>
3296 <list compact="compact">
3298 <var>prerm</var> <tt>remove</tt>
3301 <var>old-prerm</var> <tt>upgrade</tt>
3302 <var>new-version</var>
3305 <var>new-prerm</var> <tt>failed-upgrade</tt>
3306 <var>old-version</var>
3309 <var>conflictor's-prerm</var> <tt>remove</tt>
3310 <tt>in-favour</tt> <var>package</var>
3311 <var>new-version</var>
3314 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3315 <tt>in-favour</tt> <var>package-being-installed</var>
3316 <var>version</var> <tt>removing</tt>
3317 <var>conflicting-package</var>
3323 <list compact="compact">
3325 <var>postrm</var> <tt>remove</tt>
3328 <var>postrm</var> <tt>purge</tt>
3331 <var>old-postrm</var> <tt>upgrade</tt>
3332 <var>new-version</var>
3335 <var>new-postrm</var> <tt>failed-upgrade</tt>
3336 <var>old-version</var>
3339 <var>new-postrm</var> <tt>abort-install</tt>
3342 <var>new-postrm</var> <tt>abort-install</tt>
3343 <var>old-version</var>
3346 <var>new-postrm</var> <tt>abort-upgrade</tt>
3347 <var>old-version</var>
3350 <var>disappearer's-postrm</var> <tt>disappear</tt>
3351 <var>overwriter</var>
3352 <var>overwriter-version</var>
3358 <sect id="unpackphase">
3359 <heading>Details of unpack phase of installation or upgrade</heading>
3362 The procedure on installation/upgrade/overwrite/disappear
3363 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3364 stage of <tt>dpkg --install</tt>) is as follows. In each
3365 case, if a major error occurs (unless listed below) the
3366 actions are, in general, run backwards - this means that the
3367 maintainer scripts are run with different arguments in
3368 reverse order. These are the "error unwind" calls listed
3375 If a version of the package is already installed, call
3376 <example compact="compact">
3377 <var>old-prerm</var> upgrade <var>new-version</var>
3381 If the script runs but exits with a non-zero
3382 exit status, <prgn>dpkg</prgn> will attempt:
3383 <example compact="compact">
3384 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3386 Error unwind, for both the above cases:
3387 <example compact="compact">
3388 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3395 If a "conflicting" package is being removed at the same time:
3398 If any packages depended on that conflicting
3399 package and <tt>--auto-deconfigure</tt> is
3400 specified, call, for each such package:
3401 <example compact="compact">
3402 <var>deconfigured's-prerm</var> deconfigure \
3403 in-favour <var>package-being-installed</var> <var>version</var> \
3404 removing <var>conflicting-package</var> <var>version</var>
3407 <example compact="compact">
3408 <var>deconfigured's-postinst</var> abort-deconfigure \
3409 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3410 removing <var>conflicting-package</var> <var>version</var>
3412 The deconfigured packages are marked as
3413 requiring configuration, so that if
3414 <tt>--install</tt> is used they will be
3415 configured again if possible.
3418 To prepare for removal of the conflicting package, call:
3419 <example compact="compact">
3420 <var>conflictor's-prerm</var> remove \
3421 in-favour <var>package</var> <var>new-version</var>
3424 <example compact="compact">
3425 <var>conflictor's-postinst</var> abort-remove \
3426 in-favour <var>package</var> <var>new-version</var>
3435 If the package is being upgraded, call:
3436 <example compact="compact">
3437 <var>new-preinst</var> upgrade <var>old-version</var>
3441 Otherwise, if the package had some configuration
3442 files from a previous version installed (i.e., it
3443 is in the "configuration files only" state):
3444 <example compact="compact">
3445 <var>new-preinst</var> install <var>old-version</var>
3449 Otherwise (i.e., the package was completely purged):
3450 <example compact="compact">
3451 <var>new-preinst</var> install
3453 Error unwind actions, respectively:
3454 <example compact="compact">
3455 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3456 <var>new-postrm</var> abort-install <var>old-version</var>
3457 <var>new-postrm</var> abort-install
3465 The new package's files are unpacked, overwriting any
3466 that may be on the system already, for example any
3467 from the old version of the same package or from
3468 another package. Backups of the old files are kept
3469 temporarily, and if anything goes wrong the package
3470 management system will attempt to put them back as
3471 part of the error unwind.
3475 It is an error for a package to contain files which
3476 are on the system in another package, unless
3477 <tt>Replaces</tt> is used (see <ref id="replaces">).
3479 The following paragraph is not currently the case:
3480 Currently the <tt>- - force-overwrite</tt> flag is
3481 enabled, downgrading it to a warning, but this may not
3487 It is a more serious error for a package to contain a
3488 plain file or other kind of non-directory where another
3489 package has a directory (again, unless
3490 <tt>Replaces</tt> is used). This error can be
3491 overridden if desired using
3492 <tt>--force-overwrite-dir</tt>, but this is not
3497 Packages which overwrite each other's files produce
3498 behavior which, though deterministic, is hard for the
3499 system administrator to understand. It can easily
3500 lead to "missing" programs if, for example, a package
3501 is installed which overwrites a file from another
3502 package, and is then removed again.<footnote>
3503 Part of the problem is due to what is arguably a
3504 bug in <prgn>dpkg</prgn>.
3509 A directory will never be replaced by a symbolic link
3510 to a directory or vice versa; instead, the existing
3511 state (symlink or not) will be left alone and
3512 <prgn>dpkg</prgn> will follow the symlink if there is
3521 If the package is being upgraded, call
3522 <example compact="compact">
3523 <var>old-postrm</var> upgrade <var>new-version</var>
3527 If this fails, <prgn>dpkg</prgn> will attempt:
3528 <example compact="compact">
3529 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3531 Error unwind, for both cases:
3532 <example compact="compact">
3533 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3540 This is the point of no return - if
3541 <prgn>dpkg</prgn> gets this far, it won't back off
3542 past this point if an error occurs. This will
3543 leave the package in a fairly bad state, which
3544 will require a successful re-installation to clear
3545 up, but it's when <prgn>dpkg</prgn> starts doing
3546 things that are irreversible.
3551 Any files which were in the old version of the package
3552 but not in the new are removed.
3556 The new file list replaces the old.
3560 The new maintainer scripts replace the old.
3564 Any packages all of whose files have been overwritten
3565 during the installation, and which aren't required for
3566 dependencies, are considered to have been removed.
3567 For each such package
3570 <prgn>dpkg</prgn> calls:
3571 <example compact="compact">
3572 <var>disappearer's-postrm</var> disappear \
3573 <var>overwriter</var> <var>overwriter-version</var>
3577 The package's maintainer scripts are removed.
3580 It is noted in the status database as being in a
3581 sane state, namely not installed (any conffiles
3582 it may have are ignored, rather than being
3583 removed by <prgn>dpkg</prgn>). Note that
3584 disappearing packages do not have their prerm
3585 called, because <prgn>dpkg</prgn> doesn't know
3586 in advance that the package is going to
3593 Any files in the package we're unpacking that are also
3594 listed in the file lists of other packages are removed
3595 from those lists. (This will lobotomize the file list
3596 of the "conflicting" package if there is one.)
3600 The backup files made during installation, above, are
3606 The new package's status is now sane, and recorded as
3611 Here is another point of no return - if the
3612 conflicting package's removal fails we do not unwind
3613 the rest of the installation; the conflicting package
3614 is left in a half-removed limbo.
3619 If there was a conflicting package we go and do the
3620 removal actions (described below), starting with the
3621 removal of the conflicting package's files (any that
3622 are also in the package being installed have already
3623 been removed from the conflicting package's file list,
3624 and so do not get removed now).
3630 <sect id="configdetails"><heading>Details of configuration</heading>
3633 When we configure a package (this happens with <tt>dpkg
3634 --install</tt> and <tt>dpkg --configure</tt>), we first
3635 update any <tt>conffile</tt>s and then call:
3636 <example compact="compact">
3637 <var>postinst</var> configure <var>most-recently-configured-version</var>
3642 No attempt is made to unwind after errors during
3647 If there is no most recently configured version
3648 <prgn>dpkg</prgn> will pass a null argument.
3651 Historical note: Truly ancient (pre-1997) versions of
3652 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3653 (including the angle brackets) in this case. Even older
3654 ones did not pass a second argument at all, under any
3655 circumstance. Note that upgrades using such an old dpkg
3656 version are unlikely to work for other reasons, even if
3657 this old argument behavior is handled by your postinst script.
3663 <sect id="removedetails"><heading>Details of removal and/or
3664 configuration purging</heading>
3669 <example compact="compact">
3670 <var>prerm</var> remove
3674 The package's files are removed (except <tt>conffile</tt>s).
3677 <example compact="compact">
3678 <var>postrm</var> remove
3683 All the maintainer scripts except the <prgn>postrm</prgn>
3688 If we aren't purging the package we stop here. Note
3689 that packages which have no <prgn>postrm</prgn> and no
3690 <tt>conffile</tt>s are automatically purged when
3691 removed, as there is no difference except for the
3692 <prgn>dpkg</prgn> status.
3696 The <tt>conffile</tt>s and any backup files
3697 (<tt>~</tt>-files, <tt>#*#</tt> files,
3698 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3702 <example compact="compact">
3703 <var>postrm</var> purge
3707 The package's file list is removed.
3711 If there are problems during this process, we call
3712 <example compact="compact">postinst
3713 abort-remove</example>. No other attempt is made to unwind
3714 after errors during removal.
3720 <chapt id="relationships">
3721 <heading>Declaring relationships between packages</heading>
3723 <sect id="depsyntax">
3724 <heading>Syntax of relationship fields</heading>
3727 These fields all have a uniform syntax. They are a list of
3728 package names separated by commas.
3732 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3733 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3734 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3735 control file fields of the package, which declare
3736 dependencies on other packages, the package names listed may
3737 also include lists of alternative package names, separated
3738 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3739 if any one of the alternative packages is installed, that
3740 part of the dependency is considered to be satisfied.
3744 All of the fields except for <tt>Provides</tt> may restrict
3745 their applicability to particular versions of each named
3746 package. This is done in parentheses after each individual
3747 package name; the parentheses should contain a relation from
3748 the list below followed by a version number, in the format
3749 described in <ref id="f-Version">.
3753 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3754 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3755 strictly earlier, earlier or equal, exactly equal, later or
3756 equal and strictly later, respectively. The deprecated
3757 forms <tt><</tt> and <tt>></tt> were used to mean
3758 earlier/later or equal, rather than strictly earlier/later,
3759 so they should not appear in new packages (though
3760 <prgn>dpkg</prgn> still supports them).
3764 Whitespace may appear at any point in the version
3765 specification subject to the rules in <ref
3766 id="controlsyntax">, and must appear where it's necessary to
3767 disambiguate; it is not otherwise significant. For
3768 consistency and in case of future changes to
3769 <prgn>dpkg</prgn> it is recommended that a single space be
3770 used after a version relationship and before a version
3771 number; it is also conventional to put a single space after
3772 each comma, on either side of each vertical bar, and before
3773 each open parenthesis.
3777 For example, a list of dependencies might appear as:
3778 <example compact="compact">
3781 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3786 All fields that specify build-time relationships
3787 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3788 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3789 may be restricted to a certain set of architectures. This
3790 is indicated in brackets after each individual package name and
3791 the optional version specification. The brackets enclose a
3792 list of Debian architecture names separated by whitespace.
3793 Exclamation marks may be prepended to each of the names.
3794 (It is not permitted for some names to be prepended with
3795 exclamation marks and others not.) If the current Debian
3796 host architecture is not in this list and there are no
3797 exclamation marks in the list, or it is in the list with a
3798 prepended exclamation mark, the package name and the
3799 associated version specification are ignored completely for
3800 the purposes of defining the relationships.
3805 <example compact="compact">
3807 Build-Depends-Indep: texinfo
3808 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3809 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3814 Note that the binary package relationship fields such as
3815 <tt>Depends</tt> appear in one of the binary package
3816 sections of the control file, whereas the build-time
3817 relationships such as <tt>Build-Depends</tt> appear in the
3818 source package section of the control file (which is the
3823 <sect id="binarydeps">
3824 <heading>Binary Dependencies - <tt>Depends</tt>,
3825 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3826 <tt>Pre-Depends</tt>
3830 Packages can declare in their control file that they have
3831 certain relationships to other packages - for example, that
3832 they may not be installed at the same time as certain other
3833 packages, and/or that they depend on the presence of others.
3837 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3838 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3839 <tt>Conflicts</tt> control file fields.
3843 These six fields are used to declare a dependency
3844 relationship by one package on another. Except for
3845 <tt>Enhances</tt>, they appear in the depending (binary)
3846 package's control file. (<tt>Enhances</tt> appears in the
3847 recommending package's control file.)
3851 A <tt>Depends</tt> field takes effect <em>only</em> when a
3852 package is to be configured. It does not prevent a package
3853 being on the system in an unconfigured state while its
3854 dependencies are unsatisfied, and it is possible to replace
3855 a package whose dependencies are satisfied and which is
3856 properly installed with a different version whose
3857 dependencies are not and cannot be satisfied; when this is
3858 done the depending package will be left unconfigured (since
3859 attempts to configure it will give errors) and will not
3860 function properly. If it is necessary, a
3861 <tt>Pre-Depends</tt> field can be used, which has a partial
3862 effect even when a package is being unpacked, as explained
3863 in detail below. (The other three dependency fields,
3864 <tt>Recommends</tt>, <tt>Suggests</tt> and
3865 <tt>Enhances</tt>, are only used by the various front-ends
3866 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3870 For this reason packages in an installation run are usually
3871 all unpacked first and all configured later; this gives
3872 later versions of packages with dependencies on later
3873 versions of other packages the opportunity to have their
3874 dependencies satisfied.
3878 The <tt>Depends</tt> field thus allows package maintainers
3879 to impose an order in which packages should be configured.
3883 The meaning of the five dependency fields is as follows:
3885 <tag><tt>Depends</tt></tag>
3888 This declares an absolute dependency. A package will
3889 not be configured unless all of the packages listed in
3890 its <tt>Depends</tt> field have been correctly
3895 The <tt>Depends</tt> field should be used if the
3896 depended-on package is required for the depending
3897 package to provide a significant amount of
3902 The <tt>Depends</tt> field should also be used if the
3903 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3904 <prgn>postrm</prgn> scripts require the package to be
3905 present in order to run. Note, however, that the
3906 <prgn>postrm</prgn> cannot rely on any non-essential
3907 packages to be present during the <tt>purge</tt>
3911 <tag><tt>Recommends</tt></tag>
3914 This declares a strong, but not absolute, dependency.
3918 The <tt>Recommends</tt> field should list packages
3919 that would be found together with this one in all but
3920 unusual installations.
3924 <tag><tt>Suggests</tt></tag>
3926 This is used to declare that one package may be more
3927 useful with one or more others. Using this field
3928 tells the packaging system and the user that the
3929 listed packages are related to this one and can
3930 perhaps enhance its usefulness, but that installing
3931 this one without them is perfectly reasonable.
3934 <tag><tt>Enhances</tt></tag>
3936 This field is similar to Suggests but works in the
3937 opposite direction. It is used to declare that a
3938 package can enhance the functionality of another
3942 <tag><tt>Pre-Depends</tt></tag>
3945 This field is like <tt>Depends</tt>, except that it
3946 also forces <prgn>dpkg</prgn> to complete installation
3947 of the packages named before even starting the
3948 installation of the package which declares the
3949 pre-dependency, as follows:
3953 When a package declaring a pre-dependency is about to
3954 be <em>unpacked</em> the pre-dependency can be
3955 satisfied if the depended-on package is either fully
3956 configured, <em>or even if</em> the depended-on
3957 package(s) are only unpacked or half-configured,
3958 provided that they have been configured correctly at
3959 some point in the past (and not removed or partially
3960 removed since). In this case, both the
3961 previously-configured and currently unpacked or
3962 half-configured versions must satisfy any version
3963 clause in the <tt>Pre-Depends</tt> field.
3967 When the package declaring a pre-dependency is about
3968 to be <em>configured</em>, the pre-dependency will be
3969 treated as a normal <tt>Depends</tt>, that is, it will
3970 be considered satisfied only if the depended-on
3971 package has been correctly configured.
3975 <tt>Pre-Depends</tt> should be used sparingly,
3976 preferably only by packages whose premature upgrade or
3977 installation would hamper the ability of the system to
3978 continue with any upgrade that might be in progress.
3982 <tt>Pre-Depends</tt> are also required if the
3983 <prgn>preinst</prgn> script depends on the named
3984 package. It is best to avoid this situation if
3992 When selecting which level of dependency to use you should
3993 consider how important the depended-on package is to the
3994 functionality of the one declaring the dependency. Some
3995 packages are composed of components of varying degrees of
3996 importance. Such a package should list using
3997 <tt>Depends</tt> the package(s) which are required by the
3998 more important components. The other components'
3999 requirements may be mentioned as Suggestions or
4000 Recommendations, as appropriate to the components' relative
4005 <sect id="conflicts">
4006 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4009 When one binary package declares a conflict with another
4010 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4011 refuse to allow them to be installed on the system at the
4016 If one package is to be installed, the other must be removed
4017 first - if the package being installed is marked as
4018 replacing (see <ref id="replaces">) the one on the system,
4019 or the one on the system is marked as deselected, or both
4020 packages are marked <tt>Essential</tt>, then
4021 <prgn>dpkg</prgn> will automatically remove the package
4022 which is causing the conflict, otherwise it will halt the
4023 installation of the new package with an error. This
4024 mechanism is specifically designed to produce an error when
4025 the installed package is <tt>Essential</tt>, but the new
4030 A package will not cause a conflict merely because its
4031 configuration files are still installed; it must be at least
4036 A special exception is made for packages which declare a
4037 conflict with their own package name, or with a virtual
4038 package which they provide (see below): this does not
4039 prevent their installation, and allows a package to conflict
4040 with others providing a replacement for it. You use this
4041 feature when you want the package in question to be the only
4042 package providing some feature.
4046 A <tt>Conflicts</tt> entry should almost never have an
4047 "earlier than" version clause. This would prevent
4048 <prgn>dpkg</prgn> from upgrading or installing the package
4049 which declared such a conflict until the upgrade or removal
4050 of the conflicted-with package had been completed.
4054 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4058 As well as the names of actual ("concrete") packages, the
4059 package relationship fields <tt>Depends</tt>,
4060 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4061 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4062 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4063 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4064 may mention "virtual packages".
4068 A <em>virtual package</em> is one which appears in the
4069 <tt>Provides</tt> control file field of another package.
4070 The effect is as if the package(s) which provide a
4071 particular virtual package name had been listed by name
4072 everywhere the virtual package name appears. (See also <ref
4077 If there are both concrete and virtual packages of the same
4078 name, then the dependency may be satisfied (or the conflict
4079 caused) by either the concrete package with the name in
4080 question or any other concrete package which provides the
4081 virtual package with the name in question. This is so that,
4082 for example, supposing we have
4083 <example compact="compact">
4087 and someone else releases an enhanced version of the
4088 <tt>bar</tt> package (for example, a non-US variant), they
4090 <example compact="compact">
4094 and the <tt>bar-plus</tt> package will now also satisfy the
4095 dependency for the <tt>foo</tt> package.
4099 If a dependency or a conflict has a version number attached
4100 then only real packages will be considered to see whether
4101 the relationship is satisfied (or the prohibition violated,
4102 for a conflict) - it is assumed that a real package which
4103 provides the virtual package is not of the "right" version.
4104 So, a <tt>Provides</tt> field may not contain version
4105 numbers, and the version number of the concrete package
4106 which provides a particular virtual package will not be
4107 looked at when considering a dependency on or conflict with
4108 the virtual package name.
4112 It is likely that the ability will be added in a future
4113 release of <prgn>dpkg</prgn> to specify a version number for
4114 each virtual package it provides. This feature is not yet
4115 present, however, and is expected to be used only
4120 If you want to specify which of a set of real packages
4121 should be the default to satisfy a particular dependency on
4122 a virtual package, you should list the real package as an
4123 alternative before the virtual one.
4128 <sect id="replaces"><heading>Overwriting files and replacing
4129 packages - <tt>Replaces</tt></heading>
4132 Packages can declare in their control file that they should
4133 overwrite files in certain other packages, or completely
4134 replace other packages. The <tt>Replaces</tt> control file
4135 field has these two distinct purposes.
4138 <sect1><heading>Overwriting files in other packages</heading>
4141 Firstly, as mentioned before, it is usually an error for a
4142 package to contain files which are on the system in
4147 However, if the overwriting package declares that it
4148 <tt>Replaces</tt> the one containing the file being
4149 overwritten, then <prgn>dpkg</prgn> will replace the file
4150 from the old package with that from the new. The file
4151 will no longer be listed as "owned" by the old package.
4155 If a package is completely replaced in this way, so that
4156 <prgn>dpkg</prgn> does not know of any files it still
4157 contains, it is considered to have "disappeared". It will
4158 be marked as not wanted on the system (selected for
4159 removal) and not installed. Any <tt>conffile</tt>s
4160 details noted for the package will be ignored, as they
4161 will have been taken over by the overwriting package. The
4162 package's <prgn>postrm</prgn> script will be run with a
4163 special argument to allow the package to do any final
4164 cleanup required. See <ref id="mscriptsinstact">.
4167 Replaces is a one way relationship -- you have to
4168 install the replacing package after the replaced
4175 For this usage of <tt>Replaces</tt>, virtual packages (see
4176 <ref id="virtual">) are not considered when looking at a
4177 <tt>Replaces</tt> field - the packages declared as being
4178 replaced must be mentioned by their real names.
4182 Furthermore, this usage of <tt>Replaces</tt> only takes
4183 effect when both packages are at least partially on the
4184 system at once, so that it can only happen if they do not
4185 conflict or if the conflict has been overridden.
4190 <sect1><heading>Replacing whole packages, forcing their
4194 Secondly, <tt>Replaces</tt> allows the packaging system to
4195 resolve which package should be removed when there is a
4196 conflict - see <ref id="conflicts">. This usage only
4197 takes effect when the two packages <em>do</em> conflict,
4198 so that the two usages of this field do not interfere with
4203 In this situation, the package declared as being replaced
4204 can be a virtual package, so for example, all mail
4205 transport agents (MTAs) would have the following fields in
4206 their control files:
4207 <example compact="compact">
4208 Provides: mail-transport-agent
4209 Conflicts: mail-transport-agent
4210 Replaces: mail-transport-agent
4212 ensuring that only one MTA can be installed at any one
4217 <sect id="sourcebinarydeps">
4218 <heading>Relationships between source and binary packages -
4219 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4220 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4224 Source packages that require certain binary packages to be
4225 installed or absent at the time of building the package
4226 can declare relationships to those binary packages.
4230 This is done using the <tt>Build-Depends</tt>,
4231 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4232 <tt>Build-Conflicts-Indep</tt> control file fields.
4236 Build-dependencies on "build-essential" binary packages can be
4237 omitted. Please see <ref id="pkg-relations"> for more information.
4241 The dependencies and conflicts they define must be satisfied
4242 (as defined earlier for binary packages) in order to invoke
4243 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4245 If you make "build-arch" or "binary-arch", you need
4246 Build-Depends. If you make "build-indep" or
4247 "binary-indep", you need Build-Depends and
4248 Build-Depends-Indep. If you make "build" or "binary",
4252 There is no Build-Depends-Arch; the autobuilders will
4253 only need the Build-Depends if they know how to build
4254 only build-arch and binary-arch. Anyone building the
4255 build-indep/binary-indep targets is basically assumed to
4256 be building the whole package and so installs all build
4260 The purpose of the original split, I recall, was so that
4261 the autobuilders wouldn't need to install extra packages
4262 needed only for the binary-indep targets. But without a
4263 build-arch/build-indep split, this didn't work, since
4264 most of the work is done in the build target, not in the
4270 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4272 The <tt>Build-Depends</tt> and
4273 <tt>Build-Conflicts</tt> fields must be satisfied when
4274 any of the following targets is invoked:
4275 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4276 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4277 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4279 <tag><tt>Build-Depends-Indep</tt>,
4280 <tt>Build-Conflicts-Indep</tt></tag>
4282 The <tt>Build-Depends-Indep</tt> and
4283 <tt>Build-Conflicts-Indep</tt> fields must be
4284 satisfied when any of the following targets is
4285 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4286 <tt>binary</tt> and <tt>binary-indep</tt>.
4296 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4299 Packages containing shared libraries must be constructed with
4300 a little care to make sure that the shared library is always
4301 available. This is especially important for packages whose
4302 shared libraries are vitally important, such as the C library
4303 (currently <tt>libc6</tt>).
4307 Packages involving shared libraries should be split up into
4308 several binary packages. This section mostly deals with how
4309 this separation is to be accomplished; rules for files within
4310 the shared library packages are in <ref id="libraries"> instead.
4313 <sect id="sharedlibs-runtime">
4314 <heading>Run-time shared libraries</heading>
4317 The run-time shared library needs to be placed in a package called
4318 <package><var>libraryname</var><var>soversion</var></package>, where
4319 <file><var>soversion</var></file> is the version number in the
4320 soname of the shared library<footnote>
4321 The soname is the shared object name: it's the thing
4322 that has to match exactly between building an executable
4323 and running it for the dynamic linker to be able run the
4324 program. For example, if the soname of the library is
4325 <file>libfoo.so.6</file>, the library package would be
4326 called <file>libfoo6</file>.
4328 Alternatively, if it would be confusing to directly append
4329 <var>soversion</var> to <var>libraryname</var> (e.g. because
4330 <var>libraryname</var> itself ends in a number), you may use
4331 <package><var>libraryname</var>-<var>soversion</var></package> and
4332 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4337 If you have several shared libraries built from the same
4338 source tree you may lump them all together into a single
4339 shared library package, provided that you change all of
4340 their sonames at once (so that you don't get filename
4341 clashes if you try to install different versions of the
4342 combined shared libraries package).
4346 The package should install the shared libraries under
4347 their normal names. For example, the <package>libgdbm3</package>
4348 package should install <file>libgdbm.so.3.0.0</file> as
4349 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4350 renamed or re-linked by any <prgn>prerm</prgn> or
4351 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4352 of renaming things safely without affecting running programs,
4353 and attempts to interfere with this are likely to lead to
4358 Shared libraries should not be installed executable, since
4359 the dynamic linker does not require this and trying to
4360 execute a shared library usually results in a core dump.
4364 The run-time library package should include the symbolic link that
4365 <prgn>ldconfig</prgn> would create for the shared libraries.
4366 For example, the <package>libgdbm3</package> package should include
4367 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4368 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4369 linker (for example <prgn>ld.so</prgn> or
4370 <prgn>ld-linux.so.*</prgn>) can find the library between the
4371 time that <prgn>dpkg</prgn> installs it and the time that
4372 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4374 The package management system requires the library to be
4375 placed before the symbolic link pointing to it in the
4376 <file>.deb</file> file. This is so that when
4377 <prgn>dpkg</prgn> comes to install the symlink
4378 (overwriting the previous symlink pointing at an older
4379 version of the library), the new shared library is already
4380 in place. In the past, this was achieved by creating the
4381 library in the temporary packaging directory before
4382 creating the symlink. Unfortunately, this was not always
4383 effective, since the building of the tar file in the
4384 <file>.deb</file> depended on the behavior of the underlying
4385 file system. Some file systems (such as reiserfs) reorder
4386 the files so that the order of creation is forgotten.
4387 Since version 1.7.0, <prgn>dpkg</prgn>
4388 reorders the files itself as necessary when building a
4389 package. Thus it is no longer important to concern
4390 oneself with the order of file creation.
4394 <sect1 id="ldconfig">
4395 <heading><tt>ldconfig</tt></heading>
4398 Any package installing shared libraries in one of the default
4399 library directories of the dynamic linker (which are currently
4400 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4401 listed in <file>/etc/ld.so.conf</file><footnote>
4403 <list compact="compact">
4404 <item>/usr/X11R6/lib/Xaw3d</item>
4405 <item>/usr/local/lib</item>
4406 <item>/usr/lib/libc5-compat</item>
4407 <item>/lib/libc5-compat</item>
4408 <item>/usr/X11R6/lib</item>
4411 must use <prgn>ldconfig</prgn> to update the shared library
4416 The package must call <prgn>ldconfig</prgn> in the
4417 <prgn>postinst</prgn> script if the first argument is
4418 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4419 optionally invoke <prgn>ldconfig</prgn> at other times. The
4420 package should call <prgn>ldconfig</prgn> in the
4421 <prgn>postrm</prgn> script if the first argument is
4422 <tt>remove</tt>. The maintainer scripts must not invoke
4423 <prgn>ldconfig</prgn> under any circumstances other than those
4424 described in this paragraph.<footnote>
4426 During install or upgrade, the preinst is called before
4427 the new files are installed, so calling "ldconfig" is
4428 pointless. The preinst of an existing package can also be
4429 called if an upgrade fails. However, this happens during
4430 the critical time when a shared libs may exist on-disk
4431 under a temporary name. Thus, it is dangerous and
4432 forbidden by current policy to call "ldconfig" at this
4437 When a package is installed or upgraded, "postinst
4438 configure" runs after the new files are safely on-disk.
4439 Since it is perfectly safe to invoke ldconfig
4440 unconditionally in a postinst, it is OK for a package to
4441 simply put ldconfig in its postinst without checking the
4442 argument. The postinst can also be called to recover from
4443 a failed upgrade. This happens before any new files are
4444 unpacked, so there is no reason to call "ldconfig" at this
4449 For a package that is being removed, prerm is
4450 called with all the files intact, so calling ldconfig is
4451 useless. The other calls to "prerm" happen in the case of
4452 upgrade at a time when all the files of the old package
4453 are on-disk, so again calling "ldconfig" is pointless.
4457 postrm, on the other hand, is called with the "remove"
4458 argument just after the files are removed, so this is the
4459 proper time to call "ldconfig" to notify the system of the
4460 fact shared libraries from the package are removed.
4461 The postrm can be called at several other times. At the
4462 time of "postrm purge", "postrm abort-install", or "postrm
4463 abort-upgrade", calling "ldconfig" is useless because the
4464 shared lib files are not on-disk. However, when "postrm"
4465 is invoked with arguments "upgrade", "failed-upgrade", or
4466 "disappear", a shared lib may exist on-disk under a
4475 <sect id="sharedlibs-runtime-progs">
4476 <heading>Run-time support programs</heading>
4479 If your package has some run-time support programs which use
4480 the shared library you must not put them in the shared
4481 library package. If you do that then you won't be able to
4482 install several versions of the shared library without
4483 getting filename clashes.
4487 Instead, either create another package for the runtime binaries
4488 (this package might typically be named
4489 <package><var>libraryname</var>-runtime</package>; note the absence
4490 of the <var>soversion</var> in the package name), or if the
4491 development package is small, include them in there.
4495 <sect id="sharedlibs-static">
4496 <heading>Static libraries</heading>
4499 The static library (<file><var>libraryname.a</var></file>)
4500 is usually provided in addition to the shared version.
4501 It is placed into the development package (see below).
4505 In some cases, it is acceptable for a library to be
4506 available in static form only; these cases include:
4508 <item>libraries for languages whose shared library support
4509 is immature or unstable</item>
4510 <item>libraries whose interfaces are in flux or under
4511 development (commonly the case when the library's
4512 major version number is zero, or where the ABI breaks
4513 across patchlevels)</item>
4514 <item>libraries which are explicitly intended to be
4515 available only in static form by their upstream
4520 <sect id="sharedlibs-dev">
4521 <heading>Development files</heading>
4524 The development files associated to a shared library need to be
4525 placed in a package called
4526 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4527 or if you prefer only to support one development version at a
4528 time, <package><var>libraryname</var>-dev</package>.
4532 In case several development versions of a library exist, you may
4533 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4534 <ref id="conflicts">) to ensure that the user only installs one
4535 development version at a time (as different development versions are
4536 likely to have the same header files in them, which would cause a
4537 filename clash if both were installed).
4541 The development package should contain a symlink for the associated
4542 shared library without a version number. For example, the
4543 <package>libgdbm-dev</package> package should include a symlink
4544 from <file>/usr/lib/libgdbm.so</file> to
4545 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4546 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4547 <file>libgdbm.so</file> when compiling dynamically.
4551 <sect id="sharedlibs-intradeps">
4552 <heading>Dependencies between the packages of the same library</heading>
4555 Typically the development version should have an exact
4556 version dependency on the runtime library, to make sure that
4557 compilation and linking happens correctly. The
4558 <tt>${Source-Version}</tt> substitution variable can be
4559 useful for this purpose.
4563 <sect id="sharedlibs-shlibdeps">
4564 <heading>Dependencies between the library and other packages -
4565 the <tt>shlibs</tt> system</heading>
4568 If a package contains a binary or library which links to a
4569 shared library, we must ensure that when the package is
4570 installed on the system, all of the libraries needed are
4571 also installed. This requirement led to the creation of the
4572 <tt>shlibs</tt> system, which is very simple in its design:
4573 any package which <em>provides</em> a shared library also
4574 provides information on the package dependencies required to
4575 ensure the presence of this library, and any package which
4576 <em>uses</em> a shared library uses this information to
4577 determine the dependencies it requires. The files which
4578 contain the mapping from shared libraries to the necessary
4579 dependency information are called <file>shlibs</file> files.
4583 Thus, when a package is built which contains any shared
4584 libraries, it must provide a <file>shlibs</file> file for other
4585 packages to use, and when a package is built which contains
4586 any shared libraries or compiled binaries, it must run
4587 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4588 libraries used and hence the dependencies needed by this
4591 In the past, the shared libraries linked to were
4592 determined by calling <prgn>ldd</prgn>, but now
4593 <prgn>objdump</prgn> is used to do this. The only
4594 change this makes to package building is that
4595 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4596 libraries, whereas in the past this was unnecessary.
4597 The rest of this footnote explains the advantage that
4602 We say that a binary <tt>foo</tt> <em>directly</em> uses
4603 a library <tt>libbar</tt> if it is explicitly linked
4604 with that library (that is, it uses the flag
4605 <tt>-lbar</tt> during the linking stage). Other
4606 libraries that are needed by <tt>libbar</tt> are linked
4607 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4608 linker will load them automatically when it loads
4609 <tt>libbar</tt>. A package should depend on
4610 the libraries it directly uses, and the dependencies for
4611 those libraries should automatically pull in the other
4616 Unfortunately, the <prgn>ldd</prgn> program shows both
4617 the directly and indirectly used libraries, meaning that
4618 the dependencies determined included both direct and
4619 indirect dependencies. The use of <prgn>objdump</prgn>
4620 avoids this problem by determining only the directly
4625 A good example of where this helps is the following. We
4626 could update <tt>libimlib</tt> with a new version that
4627 supports a new graphics format called dgf (but retaining
4628 the same major version number). If we used the old
4629 <prgn>ldd</prgn> method, every package that uses
4630 <tt>libimlib</tt> would need to be recompiled so it
4631 would also depend on <tt>libdgf</tt> or it wouldn't run
4632 due to missing symbols. However with the new system,
4633 packages using <tt>libimlib</tt> can rely on
4634 <tt>libimlib</tt> itself having the dependency on
4635 <tt>libdgf</tt> and so they would not need rebuilding.
4641 In the following sections, we will first describe where the
4642 various <tt>shlibs</tt> files are to be found, then how to
4643 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4644 <tt>shlibs</tt> file format and how to create them if your
4645 package contains a shared library.
4649 <heading>The <tt>shlibs</tt> files present on the system</heading>
4652 There are several places where <tt>shlibs</tt> files are
4653 found. The following list gives them in the order in which
4654 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4655 one which gives the required information is used.)
4661 <p><file>debian/shlibs.local</file></p>
4664 This lists overrides for this package. Its use is
4665 described below (see <ref id="shlibslocal">).
4670 <p><file>/etc/dpkg/shlibs.override</file></p>
4673 This lists global overrides. This list is normally
4674 empty. It is maintained by the local system
4680 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4683 When packages are being built, any
4684 <file>debian/shlibs</file> files are copied into the
4685 control file area of the temporary build directory and
4686 given the name <file>shlibs</file>. These files give
4687 details of any shared libraries included in the
4689 An example may help here. Let us say that the
4690 source package <tt>foo</tt> generates two binary
4691 packages, <tt>libfoo2</tt> and
4692 <tt>foo-runtime</tt>. When building the binary
4693 packages, the two packages are created in the
4694 directories <file>debian/libfoo2</file> and
4695 <file>debian/foo-runtime</file> respectively.
4696 (<file>debian/tmp</file> could be used instead of one
4697 of these.) Since <tt>libfoo2</tt> provides the
4698 <tt>libfoo</tt> shared library, it will require a
4699 <tt>shlibs</tt> file, which will be installed in
4700 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4702 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4703 when <prgn>dpkg-shlibdeps</prgn> is run on the
4705 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4707 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4708 determine whether <tt>foo-prog</tt>'s library
4709 dependencies are satisfied by any of the libraries
4710 provided by <tt>libfoo2</tt>. For this reason,
4711 <prgn>dpkg-shlibdeps</prgn> must only be run once
4712 all of the individual binary packages'
4713 <tt>shlibs</tt> files have been installed into the
4720 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4723 These are the <file>shlibs</file> files corresponding to
4724 all of the packages installed on the system, and are
4725 maintained by the relevant package maintainers.
4730 <p><file>/etc/dpkg/shlibs.default</file></p>
4733 This file lists any shared libraries whose packages
4734 have failed to provide correct <file>shlibs</file> files.
4735 It was used when the <file>shlibs</file> setup was first
4736 introduced, but it is now normally empty. It is
4737 maintained by the <tt>dpkg</tt> maintainer.
4745 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4746 <file>shlibs</file> files</heading>
4749 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4750 <file>debian/rules</file> file. If your package contains only
4751 compiled binaries and libraries (but no scripts), you can
4752 use a command such as:
4753 <example compact="compact">
4754 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4755 debian/tmp/usr/lib/*
4757 Otherwise, you will need to explicitly list the compiled
4758 binaries and libraries.<footnote>
4759 If you are using <tt>debhelper</tt>, the
4760 <prgn>dh_shlibdeps</prgn> program will do this work for
4761 you. It will also correctly handle multi-binary
4767 This command puts the dependency information into the
4768 <file>debian/substvars</file> file, which is then used by
4769 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4770 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4771 field in the control file for this to work.
4775 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4776 done. If it does complain you might need to create your own
4777 <file>debian/shlibs.local</file> file, as explained below (see
4778 <ref id="shlibslocal">).
4782 If you have multiple binary packages, you will need to call
4783 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4784 compiled libraries or binaries. In such a case, you will
4785 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4786 utilities to specify a different <file>substvars</file> file.
4787 For more details on this and other options, see <manref
4788 name="dpkg-shlibdeps" section="1">.
4793 <heading>The <file>shlibs</file> File Format</heading>
4796 Each <file>shlibs</file> file has the same format. Lines
4797 beginning with <tt>#</tt> are considered to be comments and
4798 are ignored. Each line is of the form:
4799 <example compact="compact">
4800 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4805 We will explain this by reference to the example of the
4806 <tt>zlib1g</tt> package, which (at the time of writing)
4807 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4811 <var>library-name</var> is the name of the shared library,
4812 in this case <tt>libz</tt>. (This must match the name part
4813 of the soname, see below.)
4817 <var>soname-version-number</var> is the version part of the
4818 soname of the library. The soname is the thing that must
4819 exactly match for the library to be recognized by the
4820 dynamic linker, and is usually of the form
4821 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4822 example, <tt>libz.so.1</tt>.<footnote>
4823 This can be determined using the command
4824 <example compact="compact">
4825 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4828 The version part is the part which comes after
4829 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4833 <var>dependencies</var> has the same syntax as a dependency
4834 field in a binary package control file. It should give
4835 details of which packages are required to satisfy a binary
4836 built against the version of the library contained in the
4837 package. See <ref id="depsyntax"> for details.
4841 In our example, if the first version of the <tt>zlib1g</tt>
4842 package which contained a minor number of at least
4843 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4844 <tt>shlibs</tt> entry for this library could say:
4845 <example compact="compact">
4846 libz 1 zlib1g (>= 1:1.1.3)
4848 The version-specific dependency is to avoid warnings from
4849 the dynamic linker about using older shared libraries with
4855 <heading>Providing a <file>shlibs</file> file</heading>
4858 If your package provides a shared library, you should create
4859 a <file>shlibs</file> file following the format described above.
4860 It is usual to call this file <file>debian/shlibs</file> (but if
4861 you have multiple binary packages, you might want to call it
4862 <file>debian/shlibs.<var>package</var></file> instead). Then
4863 let <file>debian/rules</file> install it in the control area:
4864 <example compact="compact">
4865 install -m644 debian/shlibs debian/tmp/DEBIAN
4867 or, in the case of a multi-binary package:
4868 <example compact="compact">
4869 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4871 An alternative way of doing this is to create the
4872 <file>shlibs</file> file in the control area directly from
4873 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4874 file at all,<footnote>
4875 This is what <prgn>dh_makeshlibs</prgn> in the
4876 <tt>debhelper</tt> suite does.
4878 since the <file>debian/shlibs</file> file itself is ignored by
4879 <prgn>dpkg-shlibdeps</prgn>.
4883 As <prgn>dpkg-shlibdeps</prgn> reads the
4884 <file>DEBIAN/shlibs</file> files in all of the binary packages
4885 being built from this source package, all of the
4886 <file>DEBIAN/shlibs</file> files should be installed before
4887 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4892 <sect1 id="shlibslocal">
4893 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4896 This file is intended only as a <em>temporary</em> fix if
4897 your binaries or libraries depend on a library whose package
4898 does not yet provide a correct <file>shlibs</file> file.
4902 We will assume that you are trying to package a binary
4903 <tt>foo</tt>. When you try running
4904 <prgn>dpkg-shlibdeps</prgn> you get the following error
4905 message (<tt>-O</tt> displays the dependency information on
4906 <tt>stdout</tt> instead of writing it to
4907 <tt>debian/substvars</tt>, and the lines have been wrapped
4908 for ease of reading):
4909 <example compact="compact">
4910 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4911 dpkg-shlibdeps: warning: unable to find dependency
4912 information for shared library libbar (soname 1,
4913 path /usr/lib/libbar.so.1, dependency field Depends)
4914 shlibs:Depends=libc6 (>= 2.2.2-2)
4916 You can then run <prgn>ldd</prgn> on the binary to find the
4917 full location of the library concerned:
4918 <example compact="compact">
4920 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4921 libc.so.6 => /lib/libc.so.6 (0x40032000)
4922 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4924 So the <prgn>foo</prgn> binary depends on the
4925 <prgn>libbar</prgn> shared library, but no package seems to
4926 provide a <file>*.shlibs</file> file handling
4927 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4928 determine the package responsible:
4929 <example compact="compact">
4930 $ dpkg -S /usr/lib/libbar.so.1
4931 bar1: /usr/lib/libbar.so.1
4932 $ dpkg -s bar1 | grep Version
4935 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4936 is the one we are using. Now we can file a bug against the
4937 <tt>bar1</tt> package and create our own
4938 <file>debian/shlibs.local</file> to locally fix the problem.
4939 Including the following line into your
4940 <file>debian/shlibs.local</file> file:
4941 <example compact="compact">
4942 libbar 1 bar1 (>= 1.0-1)
4944 should allow the package build to work.
4948 As soon as the maintainer of <tt>bar1</tt> provides a
4949 correct <file>shlibs</file> file, you should remove this line
4950 from your <file>debian/shlibs.local</file> file. (You should
4951 probably also then have a versioned <tt>Build-Depends</tt>
4952 on <tt>bar1</tt> to help ensure that others do not have the
4953 same problem building your package.)
4962 <chapt id="opersys"><heading>The Operating System</heading>
4965 <heading>Filesystem hierarchy</heading>
4969 <heading>Filesystem Structure</heading>
4972 The location of all installed files and directories must
4973 comply with the Filesystem Hierarchy Standard (FHS),
4974 version 2.1, except where doing so would violate other
4975 terms of Debian Policy. The version of this document
4976 referred here can be found in the <tt>debian-policy</tt>
4978 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4979 name="FHS (Debian copy)"> alongside this manual (or, if
4980 you have the <package>debian-policy</package> installed,
4982 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4983 (local copy)">). The
4984 latest version, which may be a more recent version, may
4986 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4987 Specific questions about following the standard may be
4988 asked on the <tt>debian-devel</tt> mailing list, or
4989 referred to the FHS mailing list (see the
4990 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4996 <heading>Site-specific programs</heading>
4999 As mandated by the FHS, packages must not place any
5000 files in <file>/usr/local</file>, either by putting them in
5001 the file system archive to be unpacked by <prgn>dpkg</prgn>
5002 or by manipulating them in their maintainer scripts.
5006 However, the package may create empty directories below
5007 <file>/usr/local</file> so that the system administrator knows
5008 where to place site-specific files. These directories
5009 should be removed on package removal if they are
5014 Note, that this applies only to directories <em>below</em>
5015 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5016 Packages must not create sub-directories in the directory
5017 <file>/usr/local</file> itself, except those listed in FHS,
5018 section 4.5. However, you may create directories below
5019 them as you wish. You must not remove any of the
5020 directories listed in 4.5, even if you created them.
5024 Since <file>/usr/local</file> can be mounted read-only from a
5025 remote server, these directories must be created and
5026 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5027 maintainer scripts and not be included in the
5028 <file>.deb</file> archive. These scripts must not fail if
5029 either of these operations fail.
5033 For example, the <tt>emacsen-common</tt> package could
5034 contain something like
5035 <example compact="compact">
5036 if [ ! -e /usr/local/share/emacs ]
5038 if mkdir /usr/local/share/emacs 2>/dev/null
5040 chown root:staff /usr/local/share/emacs
5041 chmod 2775 /usr/local/share/emacs
5045 in its <prgn>postinst</prgn> script, and
5046 <example compact="compact">
5047 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5048 rmdir /usr/local/share/emacs 2>/dev/null || true
5050 in the <prgn>prerm</prgn> script. (Note that this form is
5051 used to ensure that if the script is interrupted, the
5052 directory <file>/usr/local/share/emacs</file> will still be
5057 If you do create a directory in <file>/usr/local</file> for
5058 local additions to a package, you should ensure that
5059 settings in <file>/usr/local</file> take precedence over the
5060 equivalents in <file>/usr</file>.
5064 However, because <file>/usr/local</file> and its contents are
5065 for exclusive use of the local administrator, a package
5066 must not rely on the presence or absence of files or
5067 directories in <file>/usr/local</file> for normal operation.
5071 The <file>/usr/local</file> directory itself and all the
5072 subdirectories created by the package should (by default) have
5073 permissions 2775 (group-writable and set-group-id) and be
5074 owned by <tt>root.staff</tt>.
5079 <heading>The system-wide mail directory</heading>
5081 The system-wide mail directory is <file>/var/mail</file>. This
5082 directory is part of the base system and should not owned
5083 by any particular mail agents. The use of the old
5084 location <file>/var/spool/mail</file> is deprecated, even
5085 though the spool may still be physically located there.
5086 To maintain partial upgrade compatibility for systems
5087 which have <file>/var/spool/mail</file> as their physical mail
5088 spool, packages using <file>/var/mail</file> must depend on
5089 either <package>libc6</package> (>= 2.1.3-13), or on
5090 <package>base-files</package> (>= 2.2.0), or on later
5091 versions of either one of these packages.
5097 <heading>Users and groups</heading>
5100 <heading>Introduction</heading>
5102 The Debian system can be configured to use either plain or
5107 Some user ids (UIDs) and group ids (GIDs) are reserved
5108 globally for use by certain packages. Because some
5109 packages need to include files which are owned by these
5110 users or groups, or need the ids compiled into binaries,
5111 these ids must be used on any Debian system only for the
5112 purpose for which they are allocated. This is a serious
5113 restriction, and we should avoid getting in the way of
5114 local administration policies. In particular, many sites
5115 allocate users and/or local system groups starting at 100.
5119 Apart from this we should have dynamically allocated ids,
5120 which should by default be arranged in some sensible
5121 order, but the behavior should be configurable.
5125 Packages other than <tt>base-passwd</tt> must not modify
5126 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5127 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5132 <heading>UID and GID classes</heading>
5134 The UID and GID numbers are divided into classes as
5140 Globally allocated by the Debian project, the same
5141 on every Debian system. These ids will appear in
5142 the <file>passwd</file> and <file>group</file> files of all
5143 Debian systems, new ids in this range being added
5144 automatically as the <tt>base-passwd</tt> package is
5149 Packages which need a single statically allocated
5150 uid or gid should use one of these; their
5151 maintainers should ask the <tt>base-passwd</tt>
5159 Dynamically allocated system users and groups.
5160 Packages which need a user or group, but can have
5161 this user or group allocated dynamically and
5162 differently on each system, should use <tt>adduser
5163 --system</tt> to create the group and/or user.
5164 <prgn>adduser</prgn> will check for the existence of
5165 the user or group, and if necessary choose an unused
5166 id based on the ranges specified in
5167 <file>adduser.conf</file>.
5171 <tag>1000-29999:</tag>
5174 Dynamically allocated user accounts. By default
5175 <prgn>adduser</prgn> will choose UIDs and GIDs for
5176 user accounts in this range, though
5177 <file>adduser.conf</file> may be used to modify this
5182 <tag>30000-59999:</tag>
5187 <tag>60000-64999:</tag>
5190 Globally allocated by the Debian project, but only
5191 created on demand. The ids are allocated centrally
5192 and statically, but the actual accounts are only
5193 created on users' systems on demand.
5197 These ids are for packages which are obscure or
5198 which require many statically-allocated ids. These
5199 packages should check for and create the accounts in
5200 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5201 <prgn>adduser</prgn> if it has this facility) if
5202 necessary. Packages which are likely to require
5203 further allocations should have a "hole" left after
5204 them in the allocation, to give them room to
5209 <tag>65000-65533:</tag>
5217 User <tt>nobody</tt>. The corresponding gid refers
5218 to the group <tt>nogroup</tt>.
5225 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5226 not</em> be used, because it is the error return
5235 <sect id="sysvinit">
5236 <heading>System run levels and <file>init.d</file> scripts</heading>
5238 <sect1 id="/etc/init.d">
5239 <heading>Introduction</heading>
5242 The <file>/etc/init.d</file> directory contains the scripts
5243 executed by <prgn>init</prgn> at boot time and when the
5244 init state (or "runlevel") is changed (see <manref
5245 name="init" section="8">).
5249 There are at least two different, yet functionally
5250 equivalent, ways of handling these scripts. For the sake
5251 of simplicity, this document describes only the symbolic
5252 link method. However, it must not be assumed by maintainer
5253 scripts that this method is being used, and any automated
5254 manipulation of the various runlevel behaviours by
5255 maintainer scripts must be performed using
5256 <prgn>update-rc.d</prgn> as described below and not by
5257 manually installing or removing symlinks. For information
5258 on the implementation details of the other method,
5259 implemented in the <tt>file-rc</tt> package, please refer
5260 to the documentation of that package.
5264 These scripts are referenced by symbolic links in the
5265 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5266 runlevels, <prgn>init</prgn> looks in the directory
5267 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5268 execute, where <tt><var>n</var></tt> is the runlevel that
5269 is being changed to, or <tt>S</tt> for the boot-up
5274 The names of the links all have the form
5275 <file>S<var>mm</var><var>script</var></file> or
5276 <file>K<var>mm</var><var>script</var></file> where
5277 <var>mm</var> is a two-digit number and <var>script</var>
5278 is the name of the script (this should be the same as the
5279 name of the actual script in <file>/etc/init.d</file>).
5283 When <prgn>init</prgn> changes runlevel first the targets
5284 of the links whose names start with a <tt>K</tt> are
5285 executed, each with the single argument <tt>stop</tt>,
5286 followed by the scripts prefixed with an <tt>S</tt>, each
5287 with the single argument <tt>start</tt>. (The links are
5288 those in the <file>/etc/rc<var>n</var>.d</file> directory
5289 corresponding to the new runlevel.) The <tt>K</tt> links
5290 are responsible for killing services and the <tt>S</tt>
5291 link for starting services upon entering the runlevel.
5295 For example, if we are changing from runlevel 2 to
5296 runlevel 3, init will first execute all of the <tt>K</tt>
5297 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5298 all of the <tt>S</tt> prefixed scripts in that directory.
5299 The links starting with <tt>K</tt> will cause the
5300 referred-to file to be executed with an argument of
5301 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5306 The two-digit number <var>mm</var> is used to determine
5307 the order in which to run the scripts: low-numbered links
5308 have their scripts run first. For example, the
5309 <tt>K20</tt> scripts will be executed before the
5310 <tt>K30</tt> scripts. This is used when a certain service
5311 must be started before another. For example, the name
5312 server <prgn>bind</prgn> might need to be started before
5313 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5314 can set up its access lists. In this case, the script
5315 that starts <prgn>bind</prgn> would have a lower number
5316 than the script that starts <prgn>inn</prgn> so that it
5318 <example compact="compact">
5325 The two runlevels 0 (halt) and 6 (reboot) are slightly
5326 different. In these runlevels, the links with an
5327 <tt>S</tt> prefix are still called after those with a
5328 <tt>K</tt> prefix, but they too are called with the single
5329 argument <tt>stop</tt>.
5333 Also, if the script name ends <tt>.sh</tt>, the script
5334 will be sourced in runlevel <tt>S</tt> rather that being
5335 run in a forked subprocess, but will be explicitly run by
5336 <prgn>sh</prgn> in all other runlevels.
5341 <heading>Writing the scripts</heading>
5344 Packages that include daemons for system services should
5345 place scripts in <file>/etc/init.d</file> to start or stop
5346 services at boot time or during a change of runlevel.
5347 These scripts should be named
5348 <file>/etc/init.d/<var>package</var></file>, and they should
5349 accept one argument, saying what to do:
5352 <tag><tt>start</tt></tag>
5353 <item>start the service,</item>
5355 <tag><tt>stop</tt></tag>
5356 <item>stop the service,</item>
5358 <tag><tt>restart</tt></tag>
5359 <item>stop and restart the service if it's already running,
5360 otherwise start the service</item>
5362 <tag><tt>reload</tt></tag>
5363 <item><p>cause the configuration of the service to be
5364 reloaded without actually stopping and restarting
5367 <tag><tt>force-reload</tt></tag>
5368 <item>cause the configuration to be reloaded if the
5369 service supports this, otherwise restart the
5373 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5374 <tt>force-reload</tt> options should be supported by all
5375 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5380 The <file>init.d</file> scripts should ensure that they will
5381 behave sensibly if invoked with <tt>start</tt> when the
5382 service is already running, or with <tt>stop</tt> when it
5383 isn't, and that they don't kill unfortunately-named user
5384 processes. The best way to achieve this is usually to use
5385 <prgn>start-stop-daemon</prgn>.
5389 If a service reloads its configuration automatically (as
5390 in the case of <prgn>cron</prgn>, for example), the
5391 <tt>reload</tt> option of the <file>init.d</file> script
5392 should behave as if the configuration has been reloaded
5397 The <file>/etc/init.d</file> scripts must be treated as
5398 configuration files, either (if they are present in the
5399 package, that is, in the .deb file) by marking them as
5400 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5401 by managing them correctly in the maintainer scripts (see
5402 <ref id="config-files">). This is important since we want
5403 to give the local system administrator the chance to adapt
5404 the scripts to the local system, e.g., to disable a
5405 service without de-installing the package, or to specify
5406 some special command line options when starting a service,
5407 while making sure her changes aren't lost during the next
5412 These scripts should not fail obscurely when the
5413 configuration files remain but the package has been
5414 removed, as configuration files remain on the system after
5415 the package has been removed. Only when <prgn>dpkg</prgn>
5416 is executed with the <tt>--purge</tt> option will
5417 configuration files be removed. In particular, as the
5418 <file>/etc/init.d/<var>package</var></file> script itself is
5419 usually a <tt>conffile</tt>, it will remain on the system
5420 if the package is removed but not purged. Therefore, you
5421 should include a <tt>test</tt> statement at the top of the
5423 <example compact="compact">
5424 test -f <var>program-executed-later-in-script</var> || exit 0
5429 Often there are some variables in the <file>init.d</file>
5430 scripts whose values control the behaviour of the scripts,
5431 and which a system administrator is likely to want to
5432 change. As the scripts themselves are frequently
5433 <tt>conffile</tt>s, modifying them requires that the
5434 administrator merge in their changes each time the package
5435 is upgraded and the <tt>conffile</tt> changes. To ease
5436 the burden on the system administrator, such configurable
5437 values should not be placed directly in the script.
5438 Instead, they should be placed in a file in
5439 <file>/etc/default</file>, which typically will have the same
5440 base name as the <file>init.d</file> script. This extra file
5441 should be sourced by the script when the script runs. It
5442 must contain only variable settings and comments in POSIX
5443 <prgn>sh</prgn> format. It may either be a
5444 <tt>conffile</tt> or a configuration file maintained by
5445 the package maintainer scripts. See <ref id="config-files">
5450 To ensure that vital configurable values are always
5451 available, the <file>init.d</file> script should set default
5452 values for each of the shell variables it uses, either
5453 before sourcing the <file>/etc/default/</file> file or
5454 afterwards using something like the <tt>:
5455 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5456 script must behave sensibly and not fail if the
5457 <file>/etc/default</file> file is deleted.
5462 <heading>Interfacing with the initscript system</heading>
5465 Maintainers should use the abstraction layer provided by
5466 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5467 programs to deal with initscripts in their packages'
5468 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5469 and <prgn>postrm</prgn>.
5473 Directly managing the /etc/rc?.d links and directly
5474 invoking the <file>/etc/init.d/</file> initscripts should
5475 be done only by packages providing the initscript
5476 subsystem (such as <prgn>sysv-rc</prgn> and
5477 <prgn>file-rc</prgn>).
5481 <heading>Managing the links</heading>
5484 The program <prgn>update-rc.d</prgn> is provided for
5485 package maintainers to arrange for the proper creation and
5486 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5487 or their functional equivalent if another method is being
5488 used. This may be used by maintainers in their packages'
5489 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5493 You must not include any <file>/etc/rc<var>n</var>.d</file>
5494 symbolic links in the actual archive or manually create or
5495 remove the symbolic links in maintainer scripts; you must
5496 use the <prgn>update-rc.d</prgn> program instead. (The
5497 former will fail if an alternative method of maintaining
5498 runlevel information is being used.) You must not include
5499 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5500 in the archive either. (Only the <tt>sysvinit</tt>
5505 By default <prgn>update-rc.d</prgn> will start services in
5506 each of the multi-user state runlevels (2, 3, 4, and 5)
5507 and stop them in the halt runlevel (0), the single-user
5508 runlevel (1) and the reboot runlevel (6). The system
5509 administrator will have the opportunity to customize
5510 runlevels by simply adding, moving, or removing the
5511 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5512 symbolic links are being used, or by modifying
5513 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5518 To get the default behavior for your package, put in your
5519 <prgn>postinst</prgn> script
5520 <example compact="compact">
5521 update-rc.d <var>package</var> defaults
5523 and in your <prgn>postrm</prgn>
5524 <example compact="compact">
5525 if [ "$1" = purge ]; then
5526 update-rc.d <var>package</var> remove
5528 </example>. Note that if your package changes runlevels
5529 or priority, you may have to remove and recreate the links,
5530 since otherwise the old links may persist. Refer to the
5531 documentation of <prgn>update-rc.d</prgn>.
5535 This will use a default sequence number of 20. If it does
5536 not matter when or in which order the <file>init.d</file>
5537 script is run, use this default. If it does, then you
5538 should talk to the maintainer of the <prgn>sysvinit</prgn>
5539 package or post to <tt>debian-devel</tt>, and they will
5540 help you choose a number.
5544 For more information about using <tt>update-rc.d</tt>,
5545 please consult its manpage <manref name="update-rc.d"
5551 <heading>Running initscripts</heading>
5553 The program <prgn>invoke-rc.d</prgn> is provided to make
5554 it easier for package maintainers to properly invoke an
5555 initscript, obeying runlevel and other locally-defined
5556 constraints that might limit a package's right to start,
5557 stop and otherwise manage services. This program may be
5558 used by maintainers in their packages' scripts.
5562 The use of <prgn>invoke-rc.d</prgn> to invoke the
5563 <file>/etc/init.d/*</file> initscripts is strongly
5564 recommended<footnote>
5565 In the future, the use of invoke-rc.d to invoke
5566 initscripts shall be made mandatory. Maintainers are
5567 advised to switch to invoke-rc.d as soon as
5569 </footnote>, instead of calling them directly.
5573 By default, <prgn>invoke-rc.d</prgn> will pass any
5574 action requests (start, stop, reload, restart...) to the
5575 <file>/etc/init.d</file> script, filtering out requests
5576 to start or restart a service out of its intended
5581 Most packages will simply need to change:
5582 <example compact="compact">/etc/init.d/<package>
5583 <action></example> in their <prgn>postinst</prgn>
5584 and <prgn>prerm</prgn> scripts to:
5585 <example compact="compact">
5586 if [ -x /usr/sbin/invoke-rc.d ] ; then
5587 invoke-rc.d <var>package</var> <action>
5589 /etc/init.d/<var>package</var> <action>
5595 A package should register its initscript services using
5596 <prgn>update-rc.d</prgn> before it tries to invoke them
5597 using <prgn>invoke-rc.d</prgn>. Invocation of
5598 unregistered services may fail.
5602 For more information about using
5603 <prgn>invoke-rc.d</prgn>, please consult its manpage
5604 <manref name="invoke-rc.d" section="8">.
5610 <heading>Boot-time initialization</heading>
5613 There used to be another directory, <file>/etc/rc.boot</file>,
5614 which contained scripts which were run once per machine
5615 boot. This has been deprecated in favour of links from
5616 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5617 described in <ref id="/etc/init.d">. Packages must not
5618 place files in <file>/etc/rc.boot</file>.
5623 <heading>Example</heading>
5626 The <prgn>bind</prgn> DNS (nameserver) package wants to
5627 make sure that the nameserver is running in multiuser
5628 runlevels, and is properly shut down with the system. It
5629 puts a script in <file>/etc/init.d</file>, naming the script
5630 appropriately <tt>bind</tt>. As you can see, the script
5631 interprets the argument <tt>reload</tt> to send the
5632 nameserver a <tt>HUP</tt> signal (causing it to reload its
5633 configuration); this way the system administrator can say
5634 <tt>/etc/init.d/bind reload</tt> to reload the name
5635 server. The script has one configurable value, which can
5636 be used to pass parameters to the named program at
5637 startup; this value is read from
5638 <file>/etc/default/bind</file> (see below).
5642 <example compact="compact">
5645 # Original version by Robert Leslie
5646 # <rob@mars.org>, edited by iwj and cs
5648 test -x /usr/sbin/named || exit 0
5650 # Source defaults file.
5652 if [ -f /etc/default/bind ]; then
5659 echo -n "Starting domain name service: named"
5660 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5665 echo -n "Stopping domain name service: named"
5666 start-stop-daemon --stop --quiet \
5667 --pidfile /var/run/named.pid --exec /usr/sbin/named
5671 echo -n "Restarting domain name service: named"
5672 start-stop-daemon --stop --quiet --oknodo \
5673 --pidfile /var/run/named.pid --exec /usr/sbin/named
5674 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5678 force-reload|reload)
5679 echo -n "Reloading configuration of domain name service: named"
5680 start-stop-daemon --stop --signal 1 --quiet \
5681 --pidfile /var/run/named.pid --exec /usr/sbin/named
5685 echo "Usage: /etc/init.d/bind " \
5686 " {start|stop|restart|reload|force-reload}" >&2
5696 Complementing the above init script is a configuration
5697 file <file>/etc/default/bind</file>, which contains
5698 configurable parameters used by the script. This would be
5699 created by the <prgn>postinst</prgn> script if it was not
5700 already present, and removed on purge by the
5701 <prgn>postrm</prgn> script.
5702 <example compact="compact">
5703 # Specified parameters to pass to named. See named(8).
5704 # You may uncomment the following line, and edit to taste.
5710 Another example on which you can base your
5711 <file>/etc/init.d</file> scripts is found in
5712 <file>/etc/init.d/skeleton</file>.
5716 If this package is happy with the default setup from
5717 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5718 and having named running in all runlevels, it can say in
5719 its <prgn>postinst</prgn>:
5720 <example compact="compact">
5721 update-rc.d bind defaults >/dev/null
5723 And in its <prgn>postrm</prgn>, to remove the links when the
5725 <example compact="compact">
5726 if [ "$1" = purge ]; then
5727 update-rc.d bind remove >/dev/null
5735 <heading>Console messages from <file>init.d</file> scripts</heading>
5738 This section describes the formats to be used for messages
5739 written to standard output by the <file>/etc/init.d</file>
5740 scripts. The intent is to improve the consistency of
5741 Debian's startup and shutdown look and feel. For this
5742 reason, please look very carefully at the details. We want
5743 the messages to have the same format in terms of wording,
5744 spaces, punctuation and case of letters.
5748 Here is a list of overall rules that you should use when you
5749 create output messages. They can be useful if you have a
5750 non-standard message that is not covered specifically in the
5757 Every message should fit in one line (fewer than 80
5758 characters), start with a capital letter and end with
5759 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5763 If you want to express that the computer is working on
5764 something (that is, performing a specific task, not
5765 starting or stopping a program), we use an "ellipsis"
5766 (three dots: <tt>...</tt>). Note that we don't insert
5767 spaces before or after the dots. If the task has been
5768 completed we write <tt>done.</tt> and a line feed.
5772 Design your messages as if the computer is telling you
5773 what he is doing (let him be polite :-), but don't
5774 mention "him" directly. For example, if you think of
5776 <example compact="compact">
5777 I'm starting network daemons: nfsd mountd.
5780 <example compact="compact">
5781 Starting network daemons: nfsd mountd.
5788 There are standard message formats for the following
5789 situations. They should be used by the <tt>init.d</tt>
5796 <p>When daemons are started</p>
5799 If your script starts one or more daemons, the output
5800 should look like this (a single line, no leading
5802 <example compact="compact">
5803 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5805 The <var>description</var> should describe the
5806 subsystem the daemon or set of daemons are part of,
5807 while <var>daemon-1</var> up to <var>daemon-n</var>
5808 denote each daemon's name (typically the file name of
5813 For example, the output of <file>/etc/init.d/lpd</file>
5815 <example compact="compact">
5816 Starting printer spooler: lpd.
5821 This can be achieved by saying
5822 <example compact="compact">
5823 echo -n "Starting printer spooler: lpd"
5824 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5827 in the script. If you have more than one daemon to
5828 start, you should do the following:
5829 <example compact="compact">
5830 echo -n "Starting remote file system services:"
5831 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5832 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5833 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5836 This makes it possible for the user to see what takes
5837 so long and when the final daemon has been started.
5838 You should be careful where to put spaces: in the
5839 example above the system administrator can easily
5840 comment out a line if he don't wants to start a
5841 specific daemon, while the displayed message still
5847 <p>When a system parameter is being set</p>
5850 If you have to set up different system parameters
5851 during the system boot, you should use this format:
5852 <example compact="compact">
5853 Setting <var>parameter</var> to "<var>value</var>".
5858 You can use a statement such as the following to get
5860 <example compact="compact">
5861 echo "Setting DNS domainname to \"$domainname\"."
5866 Note that the same symbol (<tt>"</tt>) is used for the left
5867 and right quotation marks. A grave accent (<tt>`</tt>) is
5868 not a quote character; neither is an apostrophe
5874 <p>When a daemon is stopped or restarted</p>
5877 When you stop or restart a daemon, you should issue a
5878 message identical to the startup message, except that
5879 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5880 or <tt>Restarting</tt> respectively.
5884 For example, stopping the printer daemon will like
5886 <example compact="compact">
5887 Stopping printer spooler: lpd.
5893 <p>When something is executed</p>
5896 There are several examples where you have to run a
5897 program at system startup or shutdown to perform a
5898 specific task, for example, setting the system's clock
5899 using <prgn>netdate</prgn> or killing all processes
5900 when the system shuts down. Your message should look
5902 <example compact="compact">
5903 Doing something very useful...done.
5905 You should print the <tt>done.</tt> immediately after
5906 the job has been completed, so that the user is
5907 informed why she has to wait. You can get this
5909 <example compact="compact">
5910 echo -n "Doing something very useful..."
5919 <p>When the configuration is reloaded</p>
5922 When a daemon is forced to reload its configuration
5923 files you should use the following format:
5924 <example compact="compact">
5925 Reloading <var>description</var> configuration...done.
5927 where <var>description</var> is the same as in the
5928 daemon starting message.
5936 <heading>Cron jobs</heading>
5939 Packages must not modify the configuration file
5940 <file>/etc/crontab</file>, and they must not modify the files in
5941 <file>/var/spool/cron/crontabs</file>.</p>
5944 If a package wants to install a job that has to be executed
5945 via cron, it should place a file with the name of the
5946 package in one or more of the following directories:
5947 <example compact="compact">
5952 As these directory names imply, the files within them are
5953 executed on a daily, weekly, or monthly basis,
5954 respectively. The exact times are listed in
5955 <file>/etc/crontab</file>.</p>
5958 All files installed in any of these directories must be
5959 scripts (e.g., shell scripts or Perl scripts) so that they
5960 can easily be modified by the local system administrator.
5961 In addition, they should be treated as configuration
5966 If a certain job has to be executed more frequently than
5967 daily, the package should install a file
5968 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5969 same syntax as <file>/etc/crontab</file> and is processed by
5970 <prgn>cron</prgn> automatically. The file must also be
5971 treated as a configuration file. (Note that entries in the
5972 <file>/etc/cron.d</file> directory are not handled by
5973 <prgn>anacron</prgn>. Thus, you should only use this
5974 directory for jobs which may be skipped if the system is not
5978 The scripts or crontab entries in these directories should
5979 check if all necessary programs are installed before they
5980 try to execute them. Otherwise, problems will arise when a
5981 package was removed but not purged since configuration files
5982 are kept on the system in this situation.</p>
5986 <heading>Menus</heading>
5989 The Debian <tt>menu</tt> package provides a standard
5990 interface between packages providing applications and
5991 documents, and <em>menu programs</em> (either X window
5992 managers or text-based menu programs such as
5993 <prgn>pdmenu</prgn>).
5997 All packages that provide applications that need not be
5998 passed any special command line arguments for normal
5999 operation should register a menu entry for those
6000 applications, so that users of the <tt>menu</tt> package
6001 will automatically get menu entries in their window
6002 managers, as well in shells like <tt>pdmenu</tt>.
6006 Menu entries should follow the current menu policy.
6010 The menu policy can be found in the <tt>menu-policy</tt>
6011 files in the <tt>debian-policy</tt> package.
6012 It is also available from the Debian web mirrors at
6013 <tt><url name="/doc/packaging-manuals/menu-policy/"
6014 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
6015 and from the Debian archive mirrors at
6016 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
6017 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
6021 Please also refer to the <em>Debian Menu System</em>
6022 documentation that comes with the <tt>menu</tt> package for
6023 information about how to register your applications and web
6029 <heading>Multimedia handlers</heading>
6032 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6033 is a mechanism for encoding files and data streams and
6034 providing meta-information about them, in particular their
6035 type (e.g. audio or video) and format (e.g. PNG, HTML,
6040 Registration of MIME type handlers allows programs like mail
6041 user agents and web browsers to invoke these handlers to
6042 view, edit or display MIME types they don't support directly.
6046 Packages which provide the ability to view/show/play,
6047 compose, edit or print MIME types should register themselves
6048 as such following the current MIME support policy.
6052 The MIME support policy can be found in the <tt>mime-policy</tt>
6053 files in the <tt>debian-policy</tt> package.
6054 It is also available from the Debian web mirrors at
6055 <tt><url name="/doc/packaging-manuals/mime-policy/"
6056 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
6057 and from the Debian archive mirrors at
6058 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
6059 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
6065 <heading>Keyboard configuration</heading>
6068 To achieve a consistent keyboard configuration so that all
6069 applications interpret a keyboard event the same way, all
6070 programs in the Debian distribution must be configured to
6071 comply with the following guidelines.
6075 The following keys must have the specified interpretations:
6078 <tag><tt><--</tt></tag>
6079 <item>delete the character to the left of the cursor</item>
6081 <tag><tt>Delete</tt></tag>
6082 <item>delete the character to the right of the cursor</item>
6084 <tag><tt>Control+H</tt></tag>
6085 <item>emacs: the help prefix</item>
6088 The interpretation of any keyboard events should be
6089 independent of the terminal that is used, be it a virtual
6090 console, an X terminal emulator, an rlogin/telnet session,
6095 The following list explains how the different programs
6096 should be set up to achieve this:
6102 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6106 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6110 X translations are set up to make
6111 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6112 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6113 is the vt220 escape code for the "delete character"
6114 key). This must be done by loading the X resources
6115 using <prgn>xrdb</prgn> on all local X displays, not
6116 using the application defaults, so that the
6117 translation resources used correspond to the
6118 <prgn>xmodmap</prgn> settings.
6122 The Linux console is configured to make
6123 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6124 generate <tt>ESC [ 3 ~</tt>.
6128 X applications are configured so that <tt><</tt>
6129 deletes left, and <tt>Delete</tt> deletes right. Motif
6130 applications already work like this.
6134 Terminals should have <tt>stty erase ^?</tt> .
6138 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6139 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6140 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6144 Emacs is programmed to map <tt>KB_Backspace</tt> or
6145 the <tt>stty erase</tt> character to
6146 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6147 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6148 <tt>^H</tt> to <tt>help</tt> as always.
6152 Other applications use the <tt>stty erase</tt>
6153 character and <tt>kdch1</tt> for the two delete keys,
6154 with ASCII DEL being "delete previous character" and
6155 <tt>kdch1</tt> being "delete character under
6163 This will solve the problem except for the following
6170 Some terminals have a <tt><--</tt> key that cannot
6171 be made to produce anything except <tt>^H</tt>. On
6172 these terminals Emacs help will be unavailable on
6173 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6174 character takes precedence in Emacs, and has been set
6175 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6176 available) can be used instead.
6180 Some operating systems use <tt>^H</tt> for <tt>stty
6181 erase</tt>. However, modern telnet versions and all
6182 rlogin versions propagate <tt>stty</tt> settings, and
6183 almost all UNIX versions honour <tt>stty erase</tt>.
6184 Where the <tt>stty</tt> settings are not propagated
6185 correctly, things can be made to work by using
6186 <tt>stty</tt> manually.
6190 Some systems (including previous Debian versions) use
6191 <prgn>xmodmap</prgn> to arrange for both
6192 <tt><--</tt> and <tt>Delete</tt> to generate
6193 <tt>KB_Delete</tt>. We can change the behavior of
6194 their X clients using the same X resources that we use
6195 to do it for our own clients, or configure our clients
6196 using their resources when things are the other way
6197 around. On displays configured like this
6198 <tt>Delete</tt> will not work, but <tt><--</tt>
6203 Some operating systems have different <tt>kdch1</tt>
6204 settings in their <tt>terminfo</tt> database for
6205 <tt>xterm</tt> and others. On these systems the
6206 <tt>Delete</tt> key will not work correctly when you
6207 log in from a system conforming to our policy, but
6208 <tt><--</tt> will.
6215 <heading>Environment variables</heading>
6218 A program must not depend on environment variables to get
6219 reasonable defaults. (That's because these environment
6220 variables would have to be set in a system-wide
6221 configuration file like <file>/etc/profile</file>, which is not
6222 supported by all shells.)
6226 If a program usually depends on environment variables for its
6227 configuration, the program should be changed to fall back to
6228 a reasonable default configuration if these environment
6229 variables are not present. If this cannot be done easily
6230 (e.g., if the source code of a non-free program is not
6231 available), the program must be replaced by a small
6232 "wrapper" shell script which sets the environment variables
6233 if they are not already defined, and calls the original program.
6237 Here is an example of a wrapper script for this purpose:
6239 <example compact="compact">
6241 BAR=${BAR:-/var/lib/fubar}
6243 exec /usr/lib/foo/foo "$@"
6248 Furthermore, as <file>/etc/profile</file> is a configuration
6249 file of the <prgn>base-files</prgn> package, other packages must
6250 not put any environment variables or other commands into that
6259 <heading>Files</heading>
6262 <heading>Binaries</heading>
6265 Two different packages must not install programs with
6266 different functionality but with the same filenames. (The
6267 case of two programs having the same functionality but
6268 different implementations is handled via "alternatives" or
6269 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6270 <ref id="conflicts"> respectively.) If this case happens,
6271 one of the programs must be renamed. The maintainers should
6272 report this to the <tt>debian-devel</tt> mailing list and
6273 try to find a consensus about which program will have to be
6274 renamed. If a consensus cannot be reached, <em>both</em>
6275 programs must be renamed.
6279 By default, when a package is being built, any binaries
6280 created should include debugging information, as well as
6281 being compiled with optimization. You should also turn on
6282 as many reasonable compilation warnings as possible; this
6283 makes life easier for porters, who can then look at build
6284 logs for possible problems. For the C programming language,
6285 this means the following compilation parameters should be
6287 <example compact="compact">
6289 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6291 install -s # (or use strip on the files in debian/tmp)
6296 Note that by default all installed binaries should be stripped,
6297 either by using the <tt>-s</tt> flag to
6298 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6299 the binaries after they have been copied into
6300 <file>debian/tmp</file> but before the tree is made into a
6305 Although binaries in the build tree should be compiled with
6306 debugging information by default, it can often be difficult
6307 to debug programs if they are also subjected to compiler
6308 optimization. For this reason, it is recommended to support
6309 the standardized environment
6310 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6311 contain several flags to change how a package is compiled
6319 The presence of this string means that the package
6320 should be compiled with a minimum of optimization.
6321 For C programs, it is best to add <tt>-O0</tt>
6322 to <tt>CFLAGS</tt> (although this is usually the
6323 default). Some programs might fail to build or run at
6324 this level of optimization; it may be necessary to
6325 use <tt>-O1</tt>, for example.
6329 This string means that the debugging symbols should
6330 not be stripped from the binary during installation,
6331 so that debugging information may be included in the package.
6337 The following makefile snippet is an example of how one may
6338 implement the build options; you will probably have to
6339 massage this example in order to make it work for your
6341 <example compact="compact">
6344 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6345 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6346 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6347 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6349 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6354 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6355 INSTALL_PROGRAM += -s
6361 It is up to the package maintainer to decide what
6362 compilation options are best for the package. Certain
6363 binaries (such as computationally-intensive programs) will
6364 function better with certain flags (<tt>-O3</tt>, for
6365 example); feel free to use them. Please use good judgment
6366 here. Don't use flags for the sake of it; only use them
6367 if there is good reason to do so. Feel free to override
6368 the upstream author's ideas about which compilation
6369 options are best: they are often inappropriate for our
6375 <sect id="libraries">
6376 <heading>Libraries</heading>
6379 The shared version of a library must be compiled with
6380 <tt>-fPIC</tt>, and the static version must not be. In other
6381 words, each source unit (<tt>*.c</tt>, for example, for C files)
6382 will need to be compiled twice.
6386 You must specify the gcc option <tt>-D_REENTRANT</tt>
6387 when building a library (either static or shared) to make
6388 the library compatible with LinuxThreads.
6392 Although not enforced by the build tools, shared libraries
6393 must be linked against all libraries that they use symbols from
6394 in the same way that binaries are. This ensures the correct
6395 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6396 system and guarantees that all libraries can be safely opened
6397 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6398 option <tt>-Wl,-z,defs</tt> when building a shared library.
6399 Since this option enforces symbol resolution at build time,
6400 a missing library reference will be caught early as a fatal
6405 All installed shared libraries should be stripped with
6406 <example compact="compact">
6407 strip --strip-unneeded <var>your-lib</var>
6409 (The option <tt>--strip-unneeded</tt> makes
6410 <prgn>strip</prgn> remove only the symbols which aren't
6411 needed for relocation processing.) Shared libraries can
6412 function perfectly well when stripped, since the symbols for
6413 dynamic linking are in a separate part of the ELF object
6415 You might also want to use the options
6416 <tt>--remove-section=.comment</tt> and
6417 <tt>--remove-section=.note</tt> on both shared libraries
6418 and executables, and <tt>--strip-debug</tt> on static
6424 Note that under some circumstances it may be useful to
6425 install a shared library unstripped, for example when
6426 building a separate package to support debugging.
6430 Shared object files (often <file>.so</file> files) that are not
6431 public libraries, that is, they are not meant to be linked
6432 to by third party executables (binaries of other packages),
6433 should be installed in subdirectories of the
6434 <file>/usr/lib</file> directory. Such files are exempt from the
6435 rules that govern ordinary shared libraries, except that
6436 they must not be installed executable and should be
6438 A common example are the so-called "plug-ins",
6439 internal shared objects that are dynamically loaded by
6440 programs using <manref name="dlopen" section="3">.
6445 Packages containing shared libraries that may be linked to
6446 by other packages' binaries, but which for some
6447 <em>compelling</em> reason can not be installed in
6448 <file>/usr/lib</file> directory, may install the shared library
6449 files in subdirectories of the <file>/usr/lib</file> directory,
6450 in which case they should arrange to add that directory in
6451 <file>/etc/ld.so.conf</file> in the package's post-installation
6452 script, and remove it in the package's post-removal script.
6456 An ever increasing number of packages are using
6457 <prgn>libtool</prgn> to do their linking. The latest GNU
6458 libtools (>= 1.3a) can take advantage of the metadata in the
6459 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6460 files). The main advantage of <prgn>libtool</prgn>'s
6461 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6462 store and subsequently access metadata with respect to the
6463 libraries it builds. <prgn>libtool</prgn> will search for
6464 those files, which contain a lot of useful information about
6465 a library (such as library dependency information for static
6466 linking). Also, they're <em>essential</em> for programs
6467 using <tt>libltdl</tt>.<footnote>
6468 Although <prgn>libtool</prgn> is fully capable of
6469 linking against shared libraries which don't have
6470 <tt>.la</tt> files, as it is a mere shell script it can
6471 add considerably to the build time of a
6472 <prgn>libtool</prgn>-using package if that shell script
6473 has to derive all this information from first principles
6474 for each library every time it is linked. With the
6475 advent of <prgn>libtool</prgn> version 1.4 (and to a
6476 lesser extent <prgn>libtool</prgn> version 1.3), the
6477 <file>.la</file> files also store information about
6478 inter-library dependencies which cannot necessarily be
6479 derived after the <file>.la</file> file is deleted.
6484 Packages that use <prgn>libtool</prgn> to create shared
6485 libraries should include the <file>.la</file> files in the
6486 <tt>-dev</tt> package, unless the package relies on
6487 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6488 the <tt>.la</tt> files must go in the run-time library
6493 You must make sure that you use only released versions of
6494 shared libraries to build your packages; otherwise other
6495 users will not be able to run your binaries
6496 properly. Producing source packages that depend on
6497 unreleased compilers is also usually a bad
6504 <heading>Shared libraries</heading>
6506 This section has moved to <ref id="sharedlibs">.
6512 <heading>Scripts</heading>
6515 All command scripts, including the package maintainer
6516 scripts inside the package and used by <prgn>dpkg</prgn>,
6517 should have a <tt>#!</tt> line naming the shell to be used
6522 In the case of Perl scripts this should be
6523 <tt>#!/usr/bin/perl</tt>.
6527 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6528 should almost certainly start with <tt>set -e</tt> so that
6529 errors are detected. Every script should use
6530 <tt>set -e</tt> or check the exit status of <em>every</em>
6535 The standard shell interpreter <file>/bin/sh</file> can be a
6536 symbolic link to any POSIX compatible shell, if <tt>echo
6537 -n</tt> does not generate a newline.<footnote>
6538 Debian policy specifies POSIX behavior for
6539 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6540 use in the Linux community (in particular including this
6541 policy, the Linux kernel source, many Debian scripts,
6542 etc.). This <tt>echo -n</tt> mechanism is valid but not
6543 required under POSIX, hence this explicit addition.
6544 Also, rumour has it that this shall be mandated under
6547 Thus, shell scripts specifying <file>/bin/sh</file> as
6548 interpreter should only use POSIX features. If a script
6549 requires non-POSIX features from the shell interpreter, the
6550 appropriate shell must be specified in the first line of the
6551 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6552 depend on the package providing the shell (unless the shell
6553 package is marked "Essential", as in the case of
6558 You may wish to restrict your script to POSIX features when
6559 possible so that it may use <file>/bin/sh</file> as its
6560 interpreter. If your script works with <prgn>dash</prgn>
6561 (originally called <prgn>ash</prgn>), it's probably POSIX
6562 compliant, but if you are in doubt, use
6563 <file>/bin/bash</file>.
6567 Perl scripts should check for errors when making any
6568 system calls, including <tt>open</tt>, <tt>print</tt>,
6569 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6573 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6574 scripting languages. See <em>Csh Programming Considered
6575 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6576 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
6577 If an upstream package comes with <prgn>csh</prgn> scripts
6578 then you must make sure that they start with
6579 <tt>#!/bin/csh</tt> and make your package depend on the
6580 <prgn>c-shell</prgn> virtual package.
6584 Any scripts which create files in world-writeable
6585 directories (e.g., in <file>/tmp</file>) must use a
6586 mechanism which will fail if a file with the same name
6591 The Debian base system provides the <prgn>tempfile</prgn>
6592 and <prgn>mktemp</prgn> utilities for use by scripts for
6599 <heading>Symbolic links</heading>
6602 In general, symbolic links within a top-level directory
6603 should be relative, and symbolic links pointing from one
6604 top-level directory into another should be absolute. (A
6605 top-level directory is a sub-directory of the root
6606 directory <file>/</file>.)
6610 In addition, symbolic links should be specified as short as
6611 possible, i.e., link targets like <file>foo/../bar</file> are
6616 Note that when creating a relative link using
6617 <prgn>ln</prgn> it is not necessary for the target of the
6618 link to exist relative to the working directory you're
6619 running <prgn>ln</prgn> from, nor is it necessary to change
6620 directory to the directory where the link is to be made.
6621 Simply include the string that should appear as the target
6622 of the link (this will be a pathname relative to the
6623 directory in which the link resides) as the first argument
6628 For example, in your <prgn>Makefile</prgn> or
6629 <file>debian/rules</file>, you can do things like:
6630 <example compact="compact">
6631 ln -fs gcc $(prefix)/bin/cc
6632 ln -fs gcc debian/tmp/usr/bin/cc
6633 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6634 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6639 A symbolic link pointing to a compressed file should always
6640 have the same file extension as the referenced file. (For
6641 example, if a file <file>foo.gz</file> is referenced by a
6642 symbolic link, the filename of the link has to end with
6643 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6648 <heading>Device files</heading>
6651 Packages must not include device files in the package file
6656 If a package needs any special device files that are not
6657 included in the base system, it must call
6658 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6659 after notifying the user<footnote>
6660 This notification could be done via a (low-priority)
6661 debconf message, or an echo (printf) statement.
6666 Packages must not remove any device files in the
6667 <prgn>postrm</prgn> or any other script. This is left to the
6668 system administrator.
6672 Debian uses the serial devices
6673 <file>/dev/ttyS*</file>. Programs using the old
6674 <file>/dev/cu*</file> devices should be changed to use
6675 <file>/dev/ttyS*</file>.
6679 <sect id="config-files">
6680 <heading>Configuration files</heading>
6683 <heading>Definitions</heading>
6687 <tag>configuration file</tag>
6689 A file that affects the operation of a program, or
6690 provides site- or host-specific information, or
6691 otherwise customizes the behavior of a program.
6692 Typically, configuration files are intended to be
6693 modified by the system administrator (if needed or
6694 desired) to conform to local policy or to provide
6695 more useful site-specific behavior.
6698 <tag><tt>conffile</tt></tag>
6700 A file listed in a package's <tt>conffiles</tt>
6701 file, and is treated specially by <prgn>dpkg</prgn>
6702 (see <ref id="configdetails">).
6708 The distinction between these two is important; they are
6709 not interchangeable concepts. Almost all
6710 <tt>conffile</tt>s are configuration files, but many
6711 configuration files are not <tt>conffiles</tt>.
6715 Note that a script that embeds configuration information
6716 (such as most of the files in <file>/etc/default</file> and
6717 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6718 configuration file and should be treated as such.
6723 <heading>Location</heading>
6726 Any configuration files created or used by your package
6727 must reside in <file>/etc</file>. If there are several,
6728 consider creating a subdirectory of <file>/etc</file>
6729 named after your package.
6733 If your package creates or uses configuration files
6734 outside of <file>/etc</file>, and it is not feasible to modify
6735 the package to use <file>/etc</file> directly, put the files
6736 in <file>/etc</file> and create symbolic links to those files
6737 from the location that the package requires.
6742 <heading>Behavior</heading>
6745 Configuration file handling must conform to the following
6747 <list compact="compact">
6749 local changes must be preserved during a package
6753 configuration files must be preserved when the
6754 package is removed, and only deleted when the
6761 The easy way to achieve this behavior is to make the
6762 configuration file a <tt>conffile</tt>. This is
6763 appropriate only if it is possible to distribute a default
6764 version that will work for most installations, although
6765 some system administrators may choose to modify it. This
6766 implies that the default version will be part of the
6767 package distribution, and must not be modified by the
6768 maintainer scripts during installation (or at any other
6773 In order to ensure that local changes are preserved
6774 correctly, no package may contain or make hard links to
6775 conffiles.<footnote>
6776 Rationale: There are two problems with hard links.
6777 The first is that some editors break the link while
6778 editing one of the files, so that the two files may
6779 unwittingly become unlinked and different. The second
6780 is that <prgn>dpkg</prgn> might break the hard link
6781 while upgrading <tt>conffile</tt>s.
6786 The other way to do it is via the maintainer scripts. In
6787 this case, the configuration file must not be listed as a
6788 <tt>conffile</tt> and must not be part of the package
6789 distribution. If the existence of a file is required for
6790 the package to be sensibly configured it is the
6791 responsibility of the package maintainer to provide
6792 maintainer scripts which correctly create, update and
6793 maintain the file and remove it on purge. (See <ref
6794 id="maintainerscripts"> for more information.) These
6795 scripts must be idempotent (i.e., must work correctly if
6796 <prgn>dpkg</prgn> needs to re-run them due to errors
6797 during installation or removal), must cope with all the
6798 variety of ways <prgn>dpkg</prgn> can call maintainer
6799 scripts, must not overwrite or otherwise mangle the user's
6800 configuration without asking, must not ask unnecessary
6801 questions (particularly during upgrades), and otherwise be
6806 The scripts are not required to configure every possible
6807 option for the package, but only those necessary to get
6808 the package running on a given system. Ideally the
6809 sysadmin should not have to do any configuration other
6810 than that done (semi-)automatically by the
6811 <prgn>postinst</prgn> script.
6815 A common practice is to create a script called
6816 <file><var>package</var>-configure</file> and have the
6817 package's <prgn>postinst</prgn> call it if and only if the
6818 configuration file does not already exist. In certain
6819 cases it is useful for there to be an example or template
6820 file which the maintainer scripts use. Such files should
6821 be in <file>/usr/share/<var>package</var></file> or
6822 <file>/usr/lib/<var>package</var></file> (depending on whether
6823 they are architecture-independent or not). There should
6824 be symbolic links to them from
6825 <file>/usr/share/doc/<var>package</var>/examples</file> if
6826 they are examples, and should be perfectly ordinary
6827 <prgn>dpkg</prgn>-handled files (<em>not</em>
6828 configuration files).
6832 These two styles of configuration file handling must
6833 not be mixed, for that way lies madness:
6834 <prgn>dpkg</prgn> will ask about overwriting the file
6835 every time the package is upgraded.
6840 <heading>Sharing configuration files</heading>
6843 Packages which specify the same file as a
6844 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6845 with each other. (This is an instance of the general rule
6846 about not sharing files. Note that neither alternatives
6847 nor diversions are likely to be appropriate in this case;
6848 in particular, <prgn>dpkg</prgn> does not handle diverted
6849 <tt>conffile</tt>s well.)
6853 The maintainer scripts must not alter a <tt>conffile</tt>
6854 of <em>any</em> package, including the one the scripts
6859 If two or more packages use the same configuration file
6860 and it is reasonable for both to be installed at the same
6861 time, one of these packages must be defined as
6862 <em>owner</em> of the configuration file, i.e., it will be
6863 the package which handles that file as a configuration
6864 file. Other packages that use the configuration file must
6865 depend on the owning package if they require the
6866 configuration file to operate. If the other package will
6867 use the configuration file if present, but is capable of
6868 operating without it, no dependency need be declared.
6872 If it is desirable for two or more related packages to
6873 share a configuration file <em>and</em> for all of the
6874 related packages to be able to modify that configuration
6875 file, then the following should be done:
6876 <enumlist compact="compact">
6878 One of the related packages (the "owning" package)
6879 will manage the configuration file with maintainer
6880 scripts as described in the previous section.
6883 The owning package should also provide a program
6884 that the other packages may use to modify the
6888 The related packages must use the provided program
6889 to make any desired modifications to the
6890 configuration file. They should either depend on
6891 the core package to guarantee that the configuration
6892 modifier program is available or accept gracefully
6893 that they cannot modify the configuration file if it
6894 is not. (This is in addition to the fact that the
6895 configuration file may not even be present in the
6902 Sometimes it's appropriate to create a new package which
6903 provides the basic infrastructure for the other packages
6904 and which manages the shared configuration files. (The
6905 <tt>sgml-base</tt> package is a good example.)
6910 <heading>User configuration files ("dotfiles")</heading>
6913 The files in <file>/etc/skel</file> will automatically be
6914 copied into new user accounts by <prgn>adduser</prgn>.
6915 No other program should reference the files in
6916 <file>/etc/skel</file>.
6920 Therefore, if a program needs a dotfile to exist in
6921 advance in <file>$HOME</file> to work sensibly, that dotfile
6922 should be installed in <file>/etc/skel</file> and treated as a
6927 However, programs that require dotfiles in order to
6928 operate sensibly are a bad thing, unless they do create
6929 the dotfiles themselves automatically.
6933 Furthermore, programs should be configured by the Debian
6934 default installation to behave as closely to the upstream
6935 default behaviour as possible.
6939 Therefore, if a program in a Debian package needs to be
6940 configured in some way in order to operate sensibly, that
6941 should be done using a site-wide configuration file placed
6942 in <file>/etc</file>. Only if the program doesn't support a
6943 site-wide default configuration and the package maintainer
6944 doesn't have time to add it may a default per-user file be
6945 placed in <file>/etc/skel</file>.
6949 <file>/etc/skel</file> should be as empty as we can make it.
6950 This is particularly true because there is no easy (or
6951 necessarily desirable) mechanism for ensuring that the
6952 appropriate dotfiles are copied into the accounts of
6953 existing users when a package is installed.
6959 <heading>Log files</heading>
6961 Log files should usually be named
6962 <file>/var/log/<var>package</var>.log</file>. If you have many
6963 log files, or need a separate directory for permission
6964 reasons (<file>/var/log</file> is writable only by
6965 <file>root</file>), you should usually create a directory named
6966 <file>/var/log/<var>package</var></file> and place your log
6971 Log files must be rotated occasionally so that they don't
6972 grow indefinitely; the best way to do this is to drop a log
6973 rotation configuration file into the directory
6974 <file>/etc/logrotate.d</file> and use the facilities provided by
6975 logrotate.<footnote>
6977 The traditional approach to log files has been to set up
6978 <em>ad hoc</em> log rotation schemes using simple shell
6979 scripts and cron. While this approach is highly
6980 customizable, it requires quite a lot of sysadmin work.
6981 Even though the original Debian system helped a little
6982 by automatically installing a system which can be used
6983 as a template, this was deemed not enough.
6987 The use of <prgn>logrotate</prgn>, a program developed
6988 by Red Hat, is better, as it centralizes log management.
6989 It has both a configuration file
6990 (<file>/etc/logrotate.conf</file>) and a directory where
6991 packages can drop their individual log rotation
6992 configurations (<file>/etc/logrotate.d</file>).
6995 Here is a good example for a logrotate config
6996 file (for more information see <manref name="logrotate"
6998 <example compact="compact">
6999 /var/log/foo/*.log {
7004 /etc/init.d/foo force-reload
7008 This rotates all files under <file>/var/log/foo</file>, saves 12
7009 compressed generations, and forces the daemon to reload its
7010 configuration information after the log rotation.
7014 Log files should be removed when the package is
7015 purged (but not when it is only removed). This should be
7016 done by the <prgn>postrm</prgn> script when it is called
7017 with the argument <tt>purge</tt> (see <ref
7018 id="removedetails">).
7023 <heading>Permissions and owners</heading>
7026 The rules in this section are guidelines for general use.
7027 If necessary you may deviate from the details below.
7028 However, if you do so you must make sure that what is done
7029 is secure and you should try to be as consistent as possible
7030 with the rest of the system. You should probably also
7031 discuss it on <prgn>debian-devel</prgn> first.
7035 Files should be owned by <tt>root.root</tt>, and made
7036 writable only by the owner and universally readable (and
7037 executable, if appropriate), that is mode 644 or 755.
7041 Directories should be mode 755 or (for group-writability)
7042 mode 2775. The ownership of the directory should be
7043 consistent with its mode: if a directory is mode 2775, it
7044 should be owned by the group that needs write access to
7049 Setuid and setgid executables should be mode 4755 or 2755
7050 respectively, and owned by the appropriate user or group.
7051 They should not be made unreadable (modes like 4711 or
7052 2711 or even 4111); doing so achieves no extra security,
7053 because anyone can find the binary in the freely available
7054 Debian package; it is merely inconvenient. For the same
7055 reason you should not restrict read or execute permissions
7056 on non-set-id executables.
7060 Some setuid programs need to be restricted to particular
7061 sets of users, using file permissions. In this case they
7062 should be owned by the uid to which they are set-id, and by
7063 the group which should be allowed to execute them. They
7064 should have mode 4754; again there is no point in making
7065 them unreadable to those users who must not be allowed to
7070 It is possible to arrange that the system administrator can
7071 reconfigure the package to correspond to their local
7072 security policy by changing the permissions on a binary:
7073 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7074 described below.<footnote>
7075 Ordinary files installed by <prgn>dpkg</prgn> (as
7076 opposed to <tt>conffile</tt>s and other similar objects)
7077 normally have their permissions reset to the distributed
7078 permissions when the package is reinstalled. However,
7079 the use of <prgn>dpkg-statoverride</prgn> overrides this
7080 default behaviour. If you use this method, you should
7081 remember to describe <prgn>dpkg-statoverride</prgn> in
7082 the package documentation; being a relatively new
7083 addition to Debian, it is probably not yet well-known.
7085 Another method you should consider is to create a group for
7086 people allowed to use the program(s) and make any setuid
7087 executables executable only by that group.
7091 If you need to create a new user or group for your package
7092 there are two possibilities. Firstly, you may need to
7093 make some files in the binary package be owned by this
7094 user or group, or you may need to compile the user or
7095 group id (rather than just the name) into the binary
7096 (though this latter should be avoided if possible, as in
7097 this case you need a statically allocated id).</p>
7100 If you need a statically allocated id, you must ask for a
7101 user or group id from the <tt>base-passwd</tt> maintainer,
7102 and must not release the package until you have been
7103 allocated one. Once you have been allocated one you must
7104 either make the package depend on a version of the
7105 <tt>base-passwd</tt> package with the id present in
7106 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7107 your package to create the user or group itself with the
7108 correct id (using <tt>adduser</tt>) in its
7109 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7110 the <prgn>postinst</prgn> is to be preferred if it is
7111 possible, otherwise a pre-dependency will be needed on the
7112 <tt>adduser</tt> package.)
7116 On the other hand, the program might be able to determine
7117 the uid or gid from the user or group name at runtime, so
7118 that a dynamically allocated id can be used. In this case
7119 you should choose an appropriate user or group name,
7120 discussing this on <prgn>debian-devel</prgn> and checking
7121 with the <package/base-passwd/ maintainer that it is unique and that
7122 they do not wish you to use a statically allocated id
7123 instead. When this has been checked you must arrange for
7124 your package to create the user or group if necessary using
7125 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7126 <prgn>postinst</prgn> script (again, the latter is to be
7127 preferred if it is possible).
7131 Note that changing the numeric value of an id associated
7132 with a name is very difficult, and involves searching the
7133 file system for all appropriate files. You need to think
7134 carefully whether a static or dynamic id is required, since
7135 changing your mind later will cause problems.
7138 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7140 This section is not intended as policy, but as a
7141 description of the use of <prgn>dpkg-statoverride</prgn>.
7145 <prgn>dpkg-statoverride</prgn> is a replacement for the
7146 deprecated <tt>suidmanager</tt> package. Packages which
7147 previously used <tt>suidmanager</tt> should have a
7148 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7149 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7150 and <tt>suidunregister</tt> should now be simply removed
7151 from the maintainer scripts.
7155 If a system administrator wishes to have a file (or
7156 directory or other such thing) installed with owner and
7157 permissions different from those in the distributed Debian
7158 package, he can use the <prgn>dpkg-statoverride</prgn>
7159 program to instruct <prgn>dpkg</prgn> to use the different
7160 settings every time the file is installed. Thus the
7161 package maintainer should distribute the files with their
7162 normal permissions, and leave it for the system
7163 administrator to make any desired changes. For example, a
7164 daemon which is normally required to be setuid root, but
7165 in certain situations could be used without being setuid,
7166 should be installed setuid in the <tt>.deb</tt>. Then the
7167 local system administrator can change this if they wish.
7168 If there are two standard ways of doing it, the package
7169 maintainer can use <tt>debconf</tt> to find out the
7170 preference, and call <prgn>dpkg-statoverride</prgn> in the
7171 maintainer script if necessary to accommodate the system
7172 administrator's choice.
7176 Given the above, <prgn>dpkg-statoverride</prgn> is
7177 essentially a tool for system administrators and would not
7178 normally be needed in the maintainer scripts. There is
7179 one type of situation, though, where calls to
7180 <prgn>dpkg-statoverride</prgn> would be needed in the
7181 maintainer scripts, and that involves packages which use
7182 dynamically allocated user or group ids. In such a
7183 situation, something like the following idiom can be very
7184 helpful in the package's <prgn>postinst</prgn>, where
7185 <tt>sysuser</tt> is a dynamically allocated id:
7187 for i in /usr/bin/foo /usr/sbin/bar
7189 if ! dpkg-statoverride --list $i >/dev/null
7191 dpkg-statoverride --update --add sysuser root 4755 $i
7195 The corresponding <tt>dpkg-statoverride --remove</tt>
7196 calls can then be made unconditionally when the package is
7204 <chapt id="customized-programs">
7205 <heading>Customized programs</heading>
7207 <sect id="arch-spec">
7208 <heading>Architecture specification strings</heading>
7211 If a program needs to specify an <em>architecture specification
7212 string</em> in some place, the following format should be
7213 used: <var>arch</var>-<var>os</var><footnote>
7214 The following architectures and operating systems are
7215 currently recognised by <prgn>dpkg-architecture</prgn>.
7216 The architecture, <tt><var>arch</var></tt>, is one of
7217 the following: <tt>alpha</tt>, <tt>arm</tt>,
7218 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7219 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7220 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7221 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7222 operating system, <tt><var>os</var></tt>, is one of:
7223 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7224 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7225 reserved for the GNU/Hurd operating system.
7230 Note that we don't want to use
7231 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7232 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7233 since this would make our programs incompatible with other
7234 Linux distributions. We also don't use something like
7235 <tt><var>arch</var>-unknown-linux</tt>, since the
7236 <tt>unknown</tt> does not look very good.
7241 <heading>Daemons</heading>
7244 The configuration files <file>/etc/services</file>,
7245 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7246 by the <prgn>netbase</prgn> package and must not be modified
7251 If a package requires a new entry in one of these files, the
7252 maintainer should get in contact with the
7253 <prgn>netbase</prgn> maintainer, who will add the entries
7254 and release a new version of the <prgn>netbase</prgn>
7259 The configuration file <file>/etc/inetd.conf</file> must not be
7260 modified by the package's scripts except via the
7261 <prgn>update-inetd</prgn> script or the
7262 <file>DebianNet.pm</file> Perl module. See their documentation
7263 for details on how to add entries.
7267 If a package wants to install an example entry into
7268 <file>/etc/inetd.conf</file>, the entry must be preceded with
7269 exactly one hash character (<tt>#</tt>). Such lines are
7270 treated as "commented out by user" by the
7271 <prgn>update-inetd</prgn> script and are not changed or
7272 activated during package updates.
7277 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7281 Some programs need to create pseudo-ttys. This should be done
7282 using Unix98 ptys if the C library supports it. The resulting
7283 program must not be installed setuid root, unless that
7284 is required for other functionality.
7288 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7289 <file>/var/log/lastlog</file> must be installed writeable by
7290 group <tt>utmp</tt>. Programs which need to modify those
7291 files must be installed setgid <tt>utmp</tt>.
7296 <heading>Editors and pagers</heading>
7299 Some programs have the ability to launch an editor or pager
7300 program to edit or display a text document. Since there are
7301 lots of different editors and pagers available in the Debian
7302 distribution, the system administrator and each user should
7303 have the possibility to choose his/her preferred editor and
7308 In addition, every program should choose a good default
7309 editor/pager if none is selected by the user or system
7314 Thus, every program that launches an editor or pager must
7315 use the EDITOR or PAGER environment variable to determine
7316 the editor or pager the user wishes to use. If these
7317 variables are not set, the programs <file>/usr/bin/editor</file>
7318 and <file>/usr/bin/pager</file> should be used, respectively.
7322 These two files are managed through the <prgn>dpkg</prgn>
7323 "alternatives" mechanism. Thus every package providing an
7324 editor or pager must call the
7325 <prgn>update-alternatives</prgn> script to register these
7330 If it is very hard to adapt a program to make use of the
7331 EDITOR or PAGER variables, that program may be configured to
7332 use <file>/usr/bin/sensible-editor</file> and
7333 <file>/usr/bin/sensible-pager</file> as the editor or pager
7334 program respectively. These are two scripts provided in the
7335 Debian base system that check the EDITOR and PAGER variables
7336 and launch the appropriate program, and fall back to
7337 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7338 variable is not set.
7342 A program may also use the VISUAL environment variable to
7343 determine the user's choice of editor. If it exists, it
7344 should take precedence over EDITOR. This is in fact what
7345 <file>/usr/bin/sensible-editor</file> does.
7349 It is not required for a package to depend on
7350 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7351 package to provide such virtual packages.<footnote>
7352 The Debian base system already provides an editor and a
7358 <sect id="web-appl">
7359 <heading>Web servers and applications</heading>
7362 This section describes the locations and URLs that should
7363 be used by all web servers and web applications in the
7370 Cgi-bin executable files are installed in the
7372 <example compact="compact">
7373 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7375 and should be referred to as
7376 <example compact="compact">
7377 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7382 <p>Access to HTML documents</p>
7385 HTML documents for a package are stored in
7386 <file>/usr/share/doc/<var>package</var></file>
7387 and can be referred to as
7388 <example compact="compact">
7389 http://localhost/doc/<var>package</var>/<var>filename</var>
7394 The web server should restrict access to the document
7395 tree so that only clients on the same host can read
7396 the documents. If the web server does not support such
7397 access controls, then it should not provide access at
7398 all, or ask about providing access during installation.
7403 <p>Web Document Root</p>
7406 Web Applications should try to avoid storing files in
7407 the Web Document Root. Instead they should use the
7408 /usr/share/doc/<var>package</var> directory for
7409 documents and register the Web Application via the
7410 menu package. If access to the web document root is
7411 unavoidable then use
7412 <example compact="compact">
7415 as the Document Root. This might be just a symbolic
7416 link to the location where the system administrator
7417 has put the real document root.
7425 <sect id="mail-transport-agents">
7426 <heading>Mail transport, delivery and user agents</heading>
7429 Debian packages which process electronic mail, whether mail
7430 user agents (MUAs) or mail transport agents (MTAs), must
7431 ensure that they are compatible with the configuration
7432 decisions below. Failure to do this may result in lost
7433 mail, broken <tt>From:</tt> lines, and other serious brain
7438 The mail spool is <file>/var/mail</file> and the interface to
7439 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7440 the FHS). On older systems, the mail spool may be
7441 physically located in <file>/var/spool/mail</file>, but all
7442 access to the mail spool should be via the
7443 <file>/var/mail</file> symlink. The mail spool is part of the
7444 base system and not part of the MTA package.
7448 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7449 programs (such as IMAP daemons) must lock the mailbox in an
7450 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7451 be combined with dot locking. To avoid deadlocks, a program
7452 should use <tt>fcntl()</tt> first and dot locking after
7453 this, or alternatively implement the two locking methods in
7454 a non blocking way<footnote>
7455 If it is not possible to establish both locks, the
7456 system shouldn't wait for the second lock to be
7457 established, but remove the first lock, wait a (random)
7458 time, and start over locking again.
7459 </footnote>. Using the functions <tt>maillock</tt> and
7460 <tt>mailunlock</tt> provided by the
7461 <tt>liblockfile*</tt><footnote>
7462 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7463 to use these functions.
7464 </footnote> packages is the recommended way to realize this.
7468 Mailboxes are generally mode 660
7469 <tt><var>user</var>.mail</tt> unless the system
7470 administrator has chosen otherwise. A MUA may remove a
7471 mailbox (unless it has nonstandard permissions) in which
7472 case the MTA or another MUA must recreate it if needed.
7473 Mailboxes must be writable by group mail.
7477 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7478 be setgid mail to do the locking mentioned above (and
7479 must obviously avoid accessing other users' mailboxes
7480 using this privilege).</p>
7483 <file>/etc/aliases</file> is the source file for the system mail
7484 aliases (e.g., postmaster, usenet, etc.), it is the one
7485 which the sysadmin and <prgn>postinst</prgn> scripts may
7486 edit. After <file>/etc/aliases</file> is edited the program or
7487 human editing it must call <prgn>newaliases</prgn>. All MTA
7488 packages must come with a <prgn>newaliases</prgn> program,
7489 even if it does nothing, but older MTA packages did not do
7490 this so programs should not fail if <prgn>newaliases</prgn>
7491 cannot be found. Note that because of this, all MTA
7492 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7493 <tt>Replaces: mail-transport-agent</tt> control file
7498 The convention of writing <tt>forward to
7499 <var>address</var></tt> in the mailbox itself is not
7500 supported. Use a <tt>.forward</tt> file instead.</p>
7503 The <prgn>rmail</prgn> program used by UUCP
7504 for incoming mail should be <file>/usr/sbin/rmail</file>.
7505 Likewise, <prgn>rsmtp</prgn>, for receiving
7506 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7510 If your package needs to know what hostname to use on (for
7511 example) outgoing news and mail messages which are generated
7512 locally, you should use the file <file>/etc/mailname</file>. It
7513 will contain the portion after the username and <tt>@</tt>
7514 (at) sign for email addresses of users on the machine
7515 (followed by a newline).
7519 Such package should check for the existence of this file
7520 when it is being configured. If it exists, it should be
7521 used without comment, although an MTA's configuration script
7522 may wish to prompt the user even if it finds that this file
7523 exists. If the file does not exist, the package should
7524 prompt the user for the value (preferably using
7525 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7526 as well as using it in the package's configuration. The
7527 prompt should make it clear that the name will not just be
7528 used by that package. For example, in this situation the
7529 <tt>inn</tt> package could say something like:
7530 <example compact="compact">
7531 Please enter the "mail name" of your system. This is the
7532 hostname portion of the address to be shown on outgoing
7533 news and mail messages. The default is
7534 <var>syshostname</var>, your system's host name. Mail
7535 name ["<var>syshostname</var>"]:
7537 where <var>syshostname</var> is the output of <tt>hostname
7543 <heading>News system configuration</heading>
7546 All the configuration files related to the NNTP (news)
7547 servers and clients should be located under
7548 <file>/etc/news</file>.</p>
7551 There are some configuration issues that apply to a number
7552 of news clients and server packages on the machine. These
7556 <tag><file>/etc/news/organization</file></tag>
7558 A string which should appear as the
7559 organization header for all messages posted
7560 by NNTP clients on the machine
7563 <tag><file>/etc/news/server</file></tag>
7565 Contains the FQDN of the upstream NNTP
7566 server, or localhost if the local machine is
7571 Other global files may be added as required for cross-package news
7578 <heading>Programs for the X Window System</heading>
7581 <heading>Providing X support and package priorities</heading>
7584 Programs that can be configured with support for the X
7585 Window System must be configured to do so and must declare
7586 any package dependencies necessary to satisfy their
7587 runtime requirements when using the X Window System. If
7588 such a package is of higher priority than the X packages
7589 on which it depends, it is required that either the
7590 X-specific components be split into a separate package, or
7591 that an alternative version of the package, which includes
7592 X support, be provided, or that the package's priority be
7598 <heading>Packages providing an X server</heading>
7601 Packages that provide an X server that, directly or
7602 indirectly, communicates with real input and display
7603 hardware should declare in their control data that they
7604 provide the virtual package <tt>xserver</tt>.<footnote>
7605 This implements current practice, and provides an
7606 actual policy for usage of the <tt>xserver</tt>
7607 virtual package which appears in the virtual packages
7608 list. In a nutshell, X servers that interface
7609 directly with the display and input hardware or via
7610 another subsystem (e.g., GGI) should provide
7611 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7612 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7618 <heading>Packages providing a terminal emulator</heading>
7621 Packages that provide a terminal emulator for the X Window
7622 System which meet the criteria listed below should declare
7623 in their control data that they provide the virtual
7624 package <tt>x-terminal-emulator</tt>. They should also
7625 register themselves as an alternative for
7626 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7631 To be an <tt>x-terminal-emulator</tt>, a program must:
7632 <list compact="compact">
7634 Be able to emulate a DEC VT100 terminal, or a
7635 compatible terminal.
7639 Support the command-line option <tt>-e
7640 <var>command</var></tt>, which creates a new
7641 terminal window<footnote>
7642 "New terminal window" does not necessarily mean
7643 a new top-level X window directly parented by
7644 the window manager; it could, if the terminal
7645 emulator application were so coded, be a new
7646 "view" in a multiple-document interface (MDI).
7648 and runs the specified <var>command</var>,
7649 interpreting the entirity of the rest of the command
7650 line as a command to pass straight to exec, in the
7651 manner that <tt>xterm</tt> does.
7655 Support the command-line option <tt>-T
7656 <var>title</var></tt>, which creates a new terminal
7657 window with the window title <var>title</var>.
7664 <heading>Packages providing a window manager</heading>
7667 Packages that provide a window manager should declare in
7668 their control data that they provide the virtual package
7669 <tt>x-window-manager</tt>. They should also register
7670 themselves as an alternative for
7671 <file>/usr/bin/x-window-manager</file>, with a priority
7672 calculated as follows:
7673 <list compact="compact">
7675 Start with a priority of 20.
7679 If the window manager supports the Debian menu
7680 system, add 20 points if this support is available
7681 in the package's default configuration (i.e., no
7682 configuration files belonging to the system or user
7683 have to be edited to activate the feature); if
7684 configuration files must be modified, add only 10
7690 If the window manager complies with <url
7691 id="http://www.freedesktop.org/standards/wm-spec.html"
7692 name="The Window Manager Specification Project">,
7693 written by the <url id="http://www.freedesktop.org/"
7694 name="Free Desktop Group">, add 40 points.
7698 If the window manager permits the X session to be
7699 restarted using a <em>different</em> window manager
7700 (without killing the X server) in its default
7701 configuration, add 10 points; otherwise add none.
7708 <heading>Packages providing fonts</heading>
7711 Packages that provide fonts for the X Window
7713 For the purposes of Debian Policy, a "font for the X
7714 Window System" is one which is accessed via X protocol
7715 requests. Fonts for the Linux console, for PostScript
7716 renderers, or any other purpose, do not fit this
7717 definition. Any tool which makes such fonts available
7718 to the X Window System, however, must abide by this
7721 must do a number of things to ensure that they are both
7722 available without modification of the X or font server
7723 configuration, and that they do not corrupt files used by
7724 other font packages to register information about
7728 Fonts of any type supported by the X Window System
7729 must be in a separate binary package from any
7730 executables, libraries, or documentation (except
7731 that specific to the fonts shipped, such as their
7732 license information). If one or more of the fonts
7733 so packaged are necessary for proper operation of
7734 the package with which they are associated the font
7735 package may be Recommended; if the fonts merely
7736 provide an enhancement, a Suggests relationship may
7737 be used. Packages must not Depend on font
7739 This is because the X server may retrieve fonts
7740 from the local filesystem or over the network
7741 from an X font server; the Debian package system
7742 is empowered to deal only with the local
7748 BDF fonts must be converted to PCF fonts with the
7749 <prgn>bdftopcf</prgn> utility (available in the
7750 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7751 placed in a directory that corresponds to their
7753 <list compact="compact">
7755 100 dpi fonts must be placed in
7756 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7760 75 dpi fonts must be placed in
7761 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7765 Character-cell fonts, cursor fonts, and other
7766 low-resolution fonts must be placed in
7767 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7773 Speedo fonts must be placed in
7774 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7778 Type 1 fonts must be placed in
7779 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7780 metric files are available, they must be placed here
7785 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7786 other than those listed above must be neither
7787 created nor used. (The <file>PEX</file>, <file>CID</file>,
7788 and <file>cyrillic</file> directories are excepted for
7789 historical reasons, but installation of files into
7790 these directories remains discouraged.)
7794 Font packages may, instead of placing files directly
7795 in the X font directories listed above, provide
7796 symbolic links in that font directory pointing to
7797 the files' actual location in the filesystem. Such
7798 a location must comply with the FHS.
7802 Font packages should not contain both 75dpi and
7803 100dpi versions of a font. If both are available,
7804 they should be provided in separate binary packages
7805 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7806 the names of the packages containing the
7807 corresponding fonts.
7811 Fonts destined for the <file>misc</file> subdirectory
7812 should not be included in the same package as 75dpi
7813 or 100dpi fonts; instead, they should be provided in
7814 a separate package with <tt>-misc</tt> appended to
7819 Font packages must not provide the files
7820 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7821 <file>fonts.scale</file> in a font directory:
7824 <file>fonts.dir</file> files must not be provided at all.
7828 <file>fonts.alias</file> and <file>fonts.scale</file>
7829 files, if needed, should be provided in the
7831 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7832 where <var>fontdir</var> is the name of the
7834 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7835 package's corresponding fonts are stored
7836 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7837 <var>package</var> is the name of the package
7838 that provides these fonts, and
7839 <var>extension</var> is either <tt>scale</tt>
7840 or <tt>alias</tt>, whichever corresponds to
7847 Font packages must declare a dependency on
7848 <tt>xutils (>> 4.0.3)</tt> in their control
7853 Font packages that provide one or more
7854 <file>fonts.scale</file> files as described above must
7855 invoke <prgn>update-fonts-scale</prgn> on each
7856 directory into which they installed fonts
7857 <em>before</em> invoking
7858 <prgn>update-fonts-dir</prgn> on that directory.
7859 This invocation must occur in both the
7860 <prgn>postinst</prgn> (for all arguments) and
7861 <prgn>postrm</prgn> (for all arguments except
7862 <tt>upgrade</tt>) scripts.
7866 Font packages that provide one or more
7867 <file>fonts.alias</file> files as described above must
7868 invoke <prgn>update-fonts-alias</prgn> on each
7869 directory into which they installed fonts. This
7870 invocation must occur in both the
7871 <prgn>postinst</prgn> (for all arguments) and
7872 <prgn>postrm</prgn> (for all arguments except
7873 <tt>upgrade</tt>) scripts.
7877 Font packages must invoke
7878 <prgn>update-fonts-dir</prgn> on each directory into
7879 which they installed fonts. This invocation must
7880 occur in both the <prgn>postinst</prgn> (for all
7881 arguments) and <prgn>postrm</prgn> (for all
7882 arguments except <tt>upgrade</tt>) scripts.
7886 Font packages must not provide alias names for the
7887 fonts they include which collide with alias names
7888 already in use by fonts already packaged.
7892 Font packages must not provide fonts with the same
7893 XLFD registry name as another font already packaged.
7900 <heading>Application defaults files</heading>
7903 Application defaults files must be installed in the
7904 directory <file>/etc/X11/app-defaults/</file> (use of a
7905 localized subdirectory of <file>/etc/X11/</file> as described
7906 in the <em>X Toolkit Intrinsics - C Language
7907 Interface</em> manual is also permitted). They must be
7908 registered as <tt>conffile</tt>s or handled as
7909 configuration files. Packages must not provide the
7910 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7914 Customization of programs' X resources may also be
7915 supported with the provision of a file with the same name
7916 as that of the package placed in the
7917 <file>/etc/X11/Xresources/</file> directory, which must
7918 registered as a <tt>conffile</tt> or handled as a
7919 configuration file.<footnote>
7920 Note that this mechanism is not the same as using
7921 app-defaults; app-defaults are tied to the client
7922 binary on the local filesystem, whereas X resources
7923 are stored in the X server and affect all connecting
7926 <em>Important:</em> packages that install files into the
7927 <file>/etc/X11/Xresources/</file> directory must conflict with
7928 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7929 it is possible for the installing package to destroy a
7930 previously-existing <file>/etc/X11/Xresources</file> file
7931 which had been customized by the system administrator.
7936 <heading>Installation directory issues</heading>
7939 Packages using the X Window System should not be
7940 configured to install files under the <file>/usr/X11R6/</file>
7941 directory unless they use <prgn>imake</prgn>. The
7942 <file>/usr/X11R6/</file> directory hierarchy should be
7943 regarded as deprecated for all packages except the X
7944 Window System itself, and those which use the
7945 <prgn>imake</prgn> program it provides, in which case the
7946 packages may transition out of the <file>/usr/X11R6/</file>
7947 directory at the maintainer's discretion.<footnote>
7948 <prgn>Imake</prgn>-using programs are exempt because,
7949 as long as they are written correctly, the pathnames
7950 they use to locate resources and install themselves
7951 are derived wholly from the X Window System
7952 configuration. Thus, in the event that the X Window
7953 System moves to <file>/usr/X11R7/</file>,
7954 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7955 that is required for these programs is a recompile
7956 against the corresponding X Window System library
7957 development packages.
7962 Programs that use GNU <prgn>autoconf</prgn> and
7963 <prgn>automake</prgn> are usually easily configured at
7964 compile time to use <file>/usr/</file> instead of
7965 <file>/usr/X11R6/</file>, and this should be done whenever
7966 possible. Configuration files for window managers and
7967 display managers should be placed in a subdirectory of
7968 <file>/etc/X11/</file> corresponding to the package name due
7969 to these programs' tight integration with the mechanisms
7970 of the X Window System. Application-level programs should
7971 use the <file>/etc/</file> directory unless otherwise mandated
7976 The installation of files into subdirectories
7977 of <file>/usr/X11R6/include/X11/</file> and
7978 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7979 package maintainers should determine if subdirectories of
7980 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7981 instead. (The use of symbolic links from the
7982 <file>X11R6</file> directories to other FHS-compliant
7983 locations is encouraged if the program is not easily
7984 configured to look elsewhere for its files.)
7988 Packages must not provide or install files into the directories
7989 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7990 <file>/usr/lib/X11/</file>. Files within a package should,
7991 however, make reference to these directories, rather than
7992 their <tt>X11R6</tt>-named counterparts
7993 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7994 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7995 referred to have not been moved to other FHS-compliant
8001 <heading>The OSF/Motif and OpenMotif libraries</heading>
8004 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8005 OpenMotif libraries</em><footnote>
8006 OSF/Motif and OpenMotif are collectively referred to as
8007 "Motif" in this policy document.
8009 should be compiled against and tested with LessTif (a free
8010 re-implementation of Motif) instead. If the maintainer
8011 judges that the program or programs do not work
8012 sufficiently well with LessTif to be distributed and
8013 supported, but do so when compiled against Motif, then two
8014 versions of the package should be created; one linked
8015 statically against Motif and with <tt>-smotif</tt>
8016 appended to the package name, and one linked dynamically
8017 against Motif and with <tt>-dmotif</tt> appended to the
8022 Both Motif-linked versions are dependent
8023 upon non-DFSG-compliant software and thus cannot be
8024 uploaded to the <em>main</em> distribution; if the
8025 software is itself DFSG-compliant it may be uploaded to
8026 the <em>contrib</em> distribution. While known existing
8027 versions of Motif permit unlimited redistribution of
8028 binaries linked against the library (whether statically or
8029 dynamically), it is the package maintainer's
8030 responsibility to determine whether this is permitted by
8031 the license of the copy of Motif in his or her possession.
8037 <heading>Perl programs and modules</heading>
8040 Perl programs and modules should follow the current Perl policy.
8044 The Perl policy can be found in the <tt>perl-policy</tt>
8045 files in the <tt>debian-policy</tt> package.
8046 It is also available from the Debian web mirrors at
8047 <tt><url name="/doc/packaging-manuals/perl-policy/"
8048 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
8049 and from the Debian archive mirrors at
8050 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
8051 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
8056 <heading>Emacs lisp programs</heading>
8059 Please refer to the "Debian Emacs Policy" for details of how to
8060 package emacs lisp programs.
8064 The Emacs policy is available in
8065 <file>debian-emacs-policy.gz</file> of the
8066 <package>emacsen-common</package> package.
8067 It is also available from the Debian web mirrors at
8068 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8069 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8074 <heading>Games</heading>
8077 The permissions on <file>/var/games</file> are mode 755, owner
8078 <tt>root</tt> and group <tt>root</tt>.
8082 Each game decides on its own security policy.</p>
8085 Games which require protected, privileged access to
8086 high-score files, savegames, etc., may be made
8087 set-<em>group</em>-id (mode 2755) and owned by
8088 <tt>root.games</tt>, and use files and directories with
8089 appropriate permissions (770 <tt>root.games</tt>, for
8090 example). They must not be made
8091 set-<em>user</em>-id, as this causes security problems. (If
8092 an attacker can subvert any set-user-id game they can
8093 overwrite the executable of any other, causing other players
8094 of these games to run a Trojan horse program. With a
8095 set-group-id game the attacker only gets access to less
8096 important game data, and if they can get at the other
8097 players' accounts at all it will take considerably more
8101 Some packages, for example some fortune cookie programs, are
8102 configured by the upstream authors to install with their
8103 data files or other static information made unreadable so
8104 that they can only be accessed through set-id programs
8105 provided. You should not do this in a Debian package: anyone can
8106 download the <file>.deb</file> file and read the data from it,
8107 so there is no point making the files unreadable. Not
8108 making the files unreadable also means that you don't have
8109 to make so many programs set-id, which reduces the risk of a
8113 As described in the FHS, binaries of games should be
8114 installed in the directory <file>/usr/games</file>. This also
8115 applies to games that use the X Window System. Manual pages
8116 for games (X and non-X games) should be installed in
8117 <file>/usr/share/man/man6</file>.</p>
8123 <heading>Documentation</heading>
8126 <heading>Manual pages</heading>
8129 You should install manual pages in <prgn>nroff</prgn> source
8130 form, in appropriate places under <file>/usr/share/man</file>.
8131 You should only use sections 1 to 9 (see the FHS for more
8132 details). You must not install a preformatted "cat page".
8136 Each program, utility, and function should have an
8137 associated manual page included in the same package. It is
8138 suggested that all configuration files also have a manual
8139 page included as well. Manual pages for protocols and other
8140 auxiliary things are optional.
8144 If no manual page is available, this is considered as a bug
8145 and should be reported to the Debian Bug Tracking System (the
8146 maintainer of the package is allowed to write this bug report
8147 themselves, if they so desire). Do not close the bug report
8148 until a proper manpage is available.<footnote>
8149 It is not very hard to write a man page. See the
8150 <url id="http://www.schweikhardt.net/man_page_howto.html"
8151 name="Man-Page-HOWTO">,
8152 <manref name="man" section="7">, the examples
8153 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8154 the helper programs <prgn>help2man</prgn>, or the
8155 directory <file>/usr/share/doc/man-db/examples</file>.
8160 You may forward a complaint about a missing manpage to the
8161 upstream authors, and mark the bug as forwarded in the
8162 Debian bug tracking system. Even though the GNU Project do
8163 not in general consider the lack of a manpage to be a bug,
8164 we do; if they tell you that they don't consider it a bug
8165 you should leave the bug in our bug tracking system open
8170 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8174 If one manpage needs to be accessible via several names it
8175 is better to use a symbolic link than the <file>.so</file>
8176 feature, but there is no need to fiddle with the relevant
8177 parts of the upstream source to change from <file>.so</file> to
8178 symlinks: don't do it unless it's easy. You should not
8179 create hard links in the manual page directories, nor put
8180 absolute filenames in <file>.so</file> directives. The filename
8181 in a <file>.so</file> in a manpage should be relative to the
8182 base of the manpage tree (usually
8183 <file>/usr/share/man</file>). If you do not create any links
8184 (whether symlinks, hard links, or <tt>.so</tt> directives)
8185 in the filesystem to the alternate names of the manpage,
8186 then you should not rely on <prgn>man</prgn> finding your
8187 manpage under those names based solely on the information in
8188 the manpage's header.<footnote>
8189 Supporting this in <prgn>man</prgn> often requires
8190 unreasonable processing time to find a manual page or to
8191 report that none exists, and moves knowledge into man's
8192 database that would be better left in the filesystem.
8193 This support is therefore deprecated and will cease to
8194 be present in the future.
8200 <heading>Info documents</heading>
8203 Info documents should be installed in <file>/usr/share/info</file>.
8204 They should be compressed with <tt>gzip -9</tt>.
8208 Your package should call <prgn>install-info</prgn> to update
8209 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8210 script when called with a <tt>configure</tt> argument, for
8212 <example compact="compact">
8213 install-info --quiet --section Development Development \
8214 /usr/share/info/foobar.info
8218 It is a good idea to specify a section for the location of
8219 your program; this is done with the <tt>--section</tt>
8220 switch. To determine which section to use, you should look
8221 at <file>/usr/share/info/dir</file> on your system and choose the most
8222 relevant (or create a new section if none of the current
8223 sections are relevant). Note that the <tt>--section</tt>
8224 flag takes two arguments; the first is a regular expression
8225 to match (case-insensitively) against an existing section,
8226 the second is used when creating a new one.</p>
8229 You should remove the entries in the <prgn>prerm</prgn>
8230 script when called with a <tt>remove</tt> argument:
8231 <example compact="compact">
8232 install-info --quiet --remove /usr/share/info/foobar.info
8236 If <prgn>install-info</prgn> cannot find a description entry
8237 in the Info file you must supply one. See <manref
8238 name="install-info" section="8"> for details.</p>
8242 <heading>Additional documentation</heading>
8245 Any additional documentation that comes with the package may
8246 be installed at the discretion of the package maintainer.
8247 Text documentation should be installed in the directory
8248 <file>/usr/share/doc/<var>package</var></file>, where
8249 <var>package</var> is the name of the package, and
8250 compressed with <tt>gzip -9</tt> unless it is small.
8254 If a package comes with large amounts of documentation which
8255 many users of the package will not require you should create
8256 a separate binary package to contain it, so that it does not
8257 take up disk space on the machines of users who do not need
8258 or want it installed.</p>
8261 It is often a good idea to put text information files
8262 (<file>README</file>s, changelogs, and so forth) that come with
8263 the source package in <file>/usr/share/doc/<var>package</var></file>
8264 in the binary package. However, you don't need to install
8265 the instructions for building and installing the package, of
8269 Packages must not require the existence of any files in
8270 <file>/usr/share/doc/</file> in order to function
8272 The system administrator should be able to
8273 delete files in <file>/usr/share/doc/</file> without causing
8274 any programs to break.
8276 Any files that are referenced by programs but are also
8277 useful as standalone documentation should be installed under
8278 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8279 <file>/usr/share/doc/<var>package</var></file>.
8283 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8284 link to another directory in <file>/usr/share/doc</file> only if
8285 the two packages both come from the same source and the
8286 first package Depends on the second.
8290 Former Debian releases placed all additional documentation
8291 in <file>/usr/doc/<var>package</var></file>. This has been
8292 changed to <file>/usr/share/doc/<var>package</var></file>,
8293 and packages must not put documentation in the directory
8294 <file>/usr/doc/<var>package</var></file>. <footnote>
8295 At this phase of the transition, we no longer require a
8296 symbolic link in <file>/usr/doc/</file>. At a later point,
8297 policy shall change to make the symbolic links a bug.
8303 <heading>Preferred documentation formats</heading>
8306 The unification of Debian documentation is being carried out
8310 If your package comes with extensive documentation in a
8311 markup format that can be converted to various other formats
8312 you should if possible ship HTML versions in a binary
8313 package, in the directory
8314 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8315 its subdirectories.<footnote>
8316 The rationale: The important thing here is that HTML
8317 docs should be available in <em>some</em> package, not
8318 necessarily in the main binary package.
8323 Other formats such as PostScript may be provided at the
8324 package maintainer's discretion.
8328 <sect id="copyrightfile">
8329 <heading>Copyright information</heading>
8332 Every package must be accompanied by a verbatim copy of its
8333 copyright and distribution license in the file
8334 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8335 file must neither be compressed nor be a symbolic link.
8339 In addition, the copyright file must say where the upstream
8340 sources (if any) were obtained. It should name the original
8341 authors of the package and the Debian maintainer(s) who were
8342 involved with its creation.</p>
8345 A copy of the file which will be installed in
8346 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8347 be in <file>debian/copyright</file> in the source package.
8351 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8352 link to another directory in <file>/usr/share/doc</file> only if
8353 the two packages both come from the same source and the
8354 first package Depends on the second. These rules are
8355 important because copyrights must be extractable by
8360 Packages distributed under the UCB BSD license, the Artistic
8361 license, the GNU GPL, and the GNU LGPL should refer to the
8362 files <file>/usr/share/common-licenses/BSD</file>,
8363 <file>/usr/share/common-licenses/Artistic</file>,
8364 <file>/usr/share/common-licenses/GPL</file>, and
8365 <file>/usr/share/common-licenses/LGPL</file> respectively,
8366 rather than quoting them in the copyright file.
8370 You should not use the copyright file as a general <file>README</file>
8371 file. If your package has such a file it should be
8372 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8373 <file>README.Debian</file> or some other appropriate place.</p>
8377 <heading>Examples</heading>
8380 Any examples (configurations, source files, whatever),
8381 should be installed in a directory
8382 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8383 files should not be referenced by any program: they're there
8384 for the benefit of the system administrator and users as
8385 documentation only. Architecture-specific example files
8386 should be installed in a directory
8387 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8389 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8390 latter directory itself may be a symbolic link to the
8395 If the purpose of a package is to provide examples, then the
8396 example files may be installed into
8397 <file>/usr/share/doc/<var>package</var></file>.
8401 <sect id="changelogs">
8402 <heading>Changelog files</heading>
8405 Packages that are not Debian-native must contain a
8406 compressed copy of the <file>debian/changelog</file> file from
8407 the Debian source tree in
8408 <file>/usr/share/doc/<var>package</var></file> with the name
8409 <file>changelog.Debian.gz</file>.
8413 If an upstream changelog is available, it should be accessible as
8414 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8415 plain text. If the upstream changelog is distributed in
8416 HTML, it should be made available in that form as
8417 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8418 and a plain text <file>changelog.gz</file> should be generated
8419 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8420 the upstream changelog files do not already conform to this
8421 naming convention, then this may be achieved either by
8422 renaming the files, or by adding a symbolic link, at the
8423 maintainer's discretion.<footnote>
8424 Rationale: People should not have to look in places for
8425 upstream changelogs merely because they are given
8426 different names or are distributed in HTML format.
8431 All of these files should be installed compressed using
8432 <tt>gzip -9</tt>, as they will become large with time even
8433 if they start out small.
8437 If the package has only one changelog which is used both as
8438 the Debian changelog and the upstream one because there is
8439 no separate upstream maintainer then that changelog should
8440 usually be installed as
8441 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8442 there is a separate upstream maintainer, but no upstream
8443 changelog, then the Debian changelog should still be called
8444 <file>changelog.Debian.gz</file>.
8448 For details about the format and contents of the Debian
8449 changelog file, please see <ref id="dpkgchangelog">.
8454 <appendix id="pkg-scope">
8455 <heading>Introduction and scope of these appendices</heading>
8458 These appendices are taken essentially verbatim from the
8459 now-deprecated Packaging Manual, version 3.2.1.0. They are
8460 the chapters which are likely to be of use to package
8461 maintainers and which have not already been included in the
8462 policy document itself. Most of these sections are very likely
8463 not relevant to policy; they should be treated as
8464 documentation for the packaging system. Please note that these
8465 appendices are included for convenience, and for historical
8466 reasons: they used to be part of policy package, and they have
8467 not yet been incorporated into dpkg documentation. However,
8468 they still have value, and hence they are presented here.
8472 They have not yet been checked to ensure that they are
8473 compatible with the contents of policy, and if there are any
8474 contradictions, the version in the main policy document takes
8475 precedence. The remaining chapters of the old Packaging
8476 Manual have also not been read in detail to ensure that there
8477 are not parts which have been left out. Both of these will be
8482 Certain parts of the Packaging manual were integrated into the
8483 Policy Manual proper, and removed from the appendices. Links
8484 have been placed from the old locations to the new ones.
8488 <prgn>dpkg</prgn> is a suite of programs for creating binary
8489 package files and installing and removing them on Unix
8491 <prgn>dpkg</prgn> is targetted primarily at Debian
8492 GNU/Linux, but may work on or be ported to other
8498 The binary packages are designed for the management of
8499 installed executable programs (usually compiled binaries) and
8500 their associated data, though source code examples and
8501 documentation are provided as part of some packages.</p>
8504 This manual describes the technical aspects of creating Debian
8505 binary packages (<file>.deb</file> files). It documents the
8506 behaviour of the package management programs
8507 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8508 they interact with packages.</p>
8511 It also documents the interaction between
8512 <prgn>dselect</prgn>'s core and the access method scripts it
8513 uses to actually install the selected packages, and describes
8514 how to create a new access method.</p>
8517 This manual does not go into detail about the options and
8518 usage of the package building and installation tools. It
8519 should therefore be read in conjuction with those programs'
8524 The utility programs which are provided with <prgn>dpkg</prgn>
8525 for managing various system configuration and similar issues,
8526 such as <prgn>update-rc.d</prgn> and
8527 <prgn>install-info</prgn>, are not described in detail here -
8528 please see their manpages.
8532 It is assumed that the reader is reasonably familiar with the
8533 <prgn>dpkg</prgn> System Administrators' manual.
8534 Unfortunately this manual does not yet exist.
8538 The Debian version of the FSF's GNU hello program is provided
8539 as an example for people wishing to create Debian
8540 packages. The Debian <prgn>debmake</prgn> package is
8541 recommended as a very helpful tool in creating and maintaining
8542 Debian packages. However, while the tools and examples are
8543 helpful, they do not replace the need to read and follow the
8544 Policy and Programmer's Manual.</p>
8547 <appendix id="pkg-binarypkg">
8548 <heading>Binary packages (from old Packaging Manual)</heading>
8551 The binary package has two main sections. The first part
8552 consists of various control information files and scripts used
8553 by <prgn>dpkg</prgn> when installing and removing. See <ref
8554 id="pkg-controlarea">.
8558 The second part is an archive containing the files and
8559 directories to be installed.
8563 In the future binary packages may also contain other
8564 components, such as checksums and digital signatures. The
8565 format for the archive is described in full in the
8566 <file>deb(5)</file> manpage.
8570 <sect id="pkg-bincreating"><heading>Creating package files -
8571 <prgn>dpkg-deb</prgn>
8575 All manipulation of binary package files is done by
8576 <prgn>dpkg-deb</prgn>; it's the only program that has
8577 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8578 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8579 will spot that the options requested are appropriate to
8580 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8585 In order to create a binary package you must make a
8586 directory tree which contains all the files and directories
8587 you want to have in the filesystem data part of the package.
8588 In Debian-format source packages this directory is usually
8589 <file>debian/tmp</file>, relative to the top of the package's
8594 They should have the locations (relative to the root of the
8595 directory tree you're constructing) ownerships and
8596 permissions which you want them to have on the system when
8601 With current versions of <prgn>dpkg</prgn> the uid/username
8602 and gid/groupname mappings for the users and groups being
8603 used should be the same on the system where the package is
8604 built and the one where it is installed.
8608 You need to add one special directory to the root of the
8609 miniature filesystem tree you're creating:
8610 <prgn>DEBIAN</prgn>. It should contain the control
8611 information files, notably the binary package control file
8612 (see <ref id="pkg-controlfile">).
8616 The <prgn>DEBIAN</prgn> directory will not appear in the
8617 filesystem archive of the package, and so won't be installed
8618 by <prgn>dpkg</prgn> when the package is installed.
8622 When you've prepared the package, you should invoke:
8624 dpkg --build <var>directory</var>
8629 This will build the package in
8630 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8631 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8632 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8637 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8638 to examine the contents of this newly-created file. You may find the
8639 output of following commands enlightening:
8641 dpkg-deb --info <var>filename</var>.deb
8642 dpkg-deb --contents <var>filename</var>.deb
8643 dpkg --contents <var>filename</var>.deb
8645 To view the copyright file for a package you could use this command:
8647 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8652 <sect id="pkg-controlarea">
8653 <heading>Package control information files</heading>
8656 The control information portion of a binary package is a
8657 collection of files with names known to <prgn>dpkg</prgn>.
8658 It will treat the contents of these files specially - some
8659 of them contain information used by <prgn>dpkg</prgn> when
8660 installing or removing the package; others are scripts which
8661 the package maintainer wants <prgn>dpkg</prgn> to run.
8665 It is possible to put other files in the package control
8666 area, but this is not generally a good idea (though they
8667 will largely be ignored).
8671 Here is a brief list of the control info files supported by
8672 <prgn>dpkg</prgn> and a summary of what they're used for.
8677 <tag><tt>control</tt>
8680 This is the key description file used by
8681 <prgn>dpkg</prgn>. It specifies the package's name
8682 and version, gives its description for the user,
8683 states its relationships with other packages, and so
8684 forth. See <ref id="sourcecontrolfiles"> and
8685 <ref id="binarycontrolfiles">.
8689 It is usually generated automatically from information
8690 in the source package by the
8691 <prgn>dpkg-gencontrol</prgn> program, and with
8692 assistance from <prgn>dpkg-shlibdeps</prgn>.
8693 See <ref id="pkg-sourcetools">.
8697 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8702 These are exectuable files (usually scripts) which
8703 <prgn>dpkg</prgn> runs during installation, upgrade
8704 and removal of packages. They allow the package to
8705 deal with matters which are particular to that package
8706 or require more complicated processing than that
8707 provided by <prgn>dpkg</prgn>. Details of when and
8708 how they are called are in <ref id="maintainerscripts">.
8712 It is very important to make these scripts idempotent.
8713 See <ref id="idempotency">.
8717 The maintainer scripts are guaranteed to run with a
8718 controlling terminal and can interact with the user.
8719 See <ref id="controllingterminal">.
8723 <tag><tt>conffiles</tt>
8726 This file contains a list of configuration files which
8727 are to be handled automatically by <prgn>dpkg</prgn>
8728 (see <ref id="pkg-conffiles">). Note that not necessarily
8729 every configuration file should be listed here.
8732 <tag><tt>shlibs</tt>
8735 This file contains a list of the shared libraries
8736 supplied by the package, with dependency details for
8737 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8738 when it determines what dependencies are required in a
8739 package control file. The <tt>shlibs</tt> file format
8740 is described on <ref id="shlibs">.
8745 <sect id="pkg-controlfile">
8746 <heading>The main control information file: <tt>control</tt></heading>
8749 The most important control information file used by
8750 <prgn>dpkg</prgn> when it installs a package is
8751 <tt>control</tt>. It contains all the package's "vital
8756 The binary package control files of packages built from
8757 Debian sources are made by a special tool,
8758 <prgn>dpkg-gencontrol</prgn>, which reads
8759 <file>debian/control</file> and <file>debian/changelog</file> to
8760 find the information it needs. See <ref id="pkg-sourcepkg"> for
8765 The fields in binary package control files are listed in
8766 <ref id="binarycontrolfiles">.
8770 A description of the syntax of control files and the purpose
8771 of the fields is available in <ref id="controlfields">.
8776 <heading>Time Stamps</heading>
8779 See <ref id="timestamps">.
8784 <appendix id="pkg-sourcepkg">
8785 <heading>Source packages (from old Packaging Manual) </heading>
8788 The Debian binary packages in the distribution are generated
8789 from Debian sources, which are in a special format to assist
8790 the easy and automatic building of binaries.
8793 <sect id="pkg-sourcetools">
8794 <heading>Tools for processing source packages</heading>
8797 Various tools are provided for manipulating source packages;
8798 they pack and unpack sources and help build of binary
8799 packages and help manage the distribution of new versions.
8803 They are introduced and typical uses described here; see
8804 <manref name="dpkg-source" section="1"> for full
8805 documentation about their arguments and operation.
8809 For examples of how to construct a Debian source package,
8810 and how to use those utilities that are used by Debian
8811 source packages, please see the <prgn>hello</prgn> example
8817 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8822 This program is frequently used by hand, and is also
8823 called from package-independent automated building scripts
8824 such as <prgn>dpkg-buildpackage</prgn>.
8828 To unpack a package it is typically invoked with
8830 dpkg-source -x <var>.../path/to/filename</var>.dsc
8835 with the <file><var>filename</var>.tar.gz</file> and
8836 <file><var>filename</var>.diff.gz</file> (if applicable) in
8837 the same directory. It unpacks into
8838 <file><var>package</var>-<var>version</var></file>, and if
8840 <file><var>package</var>-<var>version</var>.orig</file>, in
8841 the current directory.
8845 To create a packed source archive it is typically invoked:
8847 dpkg-source -b <var>package</var>-<var>version</var>
8852 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8853 <file>.diff.gz</file> (if appropriate) in the current
8854 directory. <prgn>dpkg-source</prgn> does not clean the
8855 source tree first - this must be done separately if it is
8860 See also <ref id="pkg-sourcearchives">.</p>
8866 <prgn>dpkg-buildpackage</prgn> - overall package-building
8871 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8872 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8873 targets <tt>clean</tt>, <tt>build</tt> and
8874 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8875 <prgn>pgp</prgn> to build a signed source and binary
8880 It is usually invoked by hand from the top level of the
8881 built or unbuilt source directory. It may be invoked with
8882 no arguments; useful arguments include:
8883 <taglist compact="compact">
8884 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8887 Do not PGP-sign the <tt>.changes</tt> file or the
8888 source package <tt>.dsc</tt> file, respectively.</p>
8890 <tag><tt>-p<var>pgp-command</var></tt></tag>
8893 Invoke <var>pgp-command</var> instead of finding
8894 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8895 <var>pgp-command</var> must behave just like
8896 <prgn>pgp</prgn>.</p>
8898 <tag><tt>-r<var>root-command</var></tt></tag>
8901 When root privilege is required, invoke the command
8902 <var>root-command</var>. <var>root-command</var>
8903 should invoke its first argument as a command, from
8904 the <prgn>PATH</prgn> if necessary, and pass its
8905 second and subsequent arguments to the command it
8906 calls. If no <var>root-command</var> is supplied
8907 then <var>dpkg-buildpackage</var> will take no
8908 special action to gain root privilege, so that for
8909 most packages it will have to be invoked as root to
8912 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8915 Two types of binary-only build and upload - see
8916 <manref name="dpkg-source" section="1">.
8925 <prgn>dpkg-gencontrol</prgn> - generates binary package
8930 This program is usually called from <file>debian/rules</file>
8931 (see <ref id="pkg-sourcetree">) in the top level of the source
8936 This is usually done just before the files and directories in the
8937 temporary directory tree where the package is being built have their
8938 permissions and ownerships set and the package is constructed using
8939 <prgn>dpkg-deb/</prgn>
8941 This is so that the control file which is produced has
8942 the right permissions
8947 <prgn>dpkg-gencontrol</prgn> must be called after all the
8948 files which are to go into the package have been placed in
8949 the temporary build directory, so that its calculation of
8950 the installed size of a package is correct.
8954 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8955 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8956 variable substitutions created by
8957 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8962 For a package which generates only one binary package, and
8963 which builds it in <file>debian/tmp</file> relative to the top
8964 of the source package, it is usually sufficient to call
8965 <prgn>dpkg-gencontrol</prgn>.
8969 Sources which build several binaries will typically need
8972 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8973 </example> The <tt>-P</tt> tells
8974 <prgn>dpkg-gencontrol</prgn> that the package is being
8975 built in a non-default directory, and the <tt>-p</tt>
8976 tells it which package's control file should be generated.
8980 <prgn>dpkg-gencontrol</prgn> also adds information to the
8981 list of files in <file>debian/files</file>, for the benefit of
8982 (for example) a future invocation of
8983 <prgn>dpkg-genchanges</prgn>.</p>
8988 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8993 This program is usually called from <file>debian/rules</file>
8994 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8995 id="pkg-sourcetree">), in the top level of the source tree.
8999 Its arguments are executables.
9002 In a forthcoming dpkg version,
9003 <prgn>dpkg-shlibdeps</prgn> would be required to be
9004 called on shared libraries as well.
9007 They may be specified either in the locations in the
9008 source tree where they are created or in the locations
9009 in the temporary build tree where they are installed
9010 prior to binary package creation.
9012 </footnote> for which shared library dependencies should
9013 be included in the binary package's control file.
9017 If some of the found shared libraries should only
9018 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9019 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9020 by using the <tt>-d<var>dependency-field</var></tt> option
9021 before those executable(s). (Each <tt>-d</tt> option
9022 takes effect until the next <tt>-d</tt>.)
9026 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9027 output control file to be modified. Instead by default it
9028 adds to the <file>debian/substvars</file> file variable
9029 settings like <tt>shlibs:Depends</tt>. These variable
9030 settings must be referenced in dependency fields in the
9031 appropriate per-binary-package sections of the source
9036 For example, the <prgn>procps</prgn> package generates two
9037 kinds of binaries, simple C binaries like <prgn>ps</prgn>
9038 which require a predependency and full-screen ncurses
9039 binaries like <prgn>top</prgn> which require only a
9040 recommendation. It can say in its <file>debian/rules</file>:
9042 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
9044 and then in its main control file <file>debian/control</file>:
9048 Pre-Depends: ${shlibs:Pre-Depends}
9049 Recommends: ${shlibs:Recommends}
9055 Sources which produce several binary packages with
9056 different shared library dependency requirements can use
9057 the <tt>-p<var>varnameprefix</var></tt> option to override
9058 the default <tt>shlibs:</tt> prefix (one invocation of
9059 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9060 They can thus produce several sets of dependency
9061 variables, each of the form
9062 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9063 which can be referred to in the appropriate parts of the
9064 binary package control files.
9071 <prgn>dpkg-distaddfile</prgn> - adds a file to
9072 <file>debian/files</file>
9076 Some packages' uploads need to include files other than
9077 the source and binary package files.
9081 <prgn>dpkg-distaddfile</prgn> adds a file to the
9082 <file>debian/files</file> file so that it will be included in
9083 the <file>.changes</file> file when
9084 <prgn>dpkg-genchanges</prgn> is run.
9088 It is usually invoked from the <tt>binary</tt> target of
9089 <file>debian/rules</file>:
9091 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9093 The <var>filename</var> is relative to the directory where
9094 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9095 is usually the directory above the top level of the source
9096 tree. The <file>debian/rules</file> target should put the
9097 file there just before or just after calling
9098 <prgn>dpkg-distaddfile</prgn>.
9102 The <var>section</var> and <var>priority</var> are passed
9103 unchanged into the resulting <file>.changes</file> file.
9108 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
9113 This program is usually called by package-independent
9114 automatic building scripts such as
9115 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9120 It is usually called in the top level of a built source
9121 tree, and when invoked with no arguments will print out a
9122 straightforward <file>.changes</file> file based on the
9123 information in the source package's changelog and control
9124 file and the binary and source packages which should have
9130 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
9135 This program is used internally by
9136 <prgn>dpkg-source</prgn> et al. It may also occasionally
9137 be useful in <file>debian/rules</file> and elsewhere. It
9138 parses a changelog, <file>debian/changelog</file> by default,
9139 and prints a control-file format representation of the
9140 information in it to standard output.
9144 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
9145 information about the build and host system
9149 This program can be used manually, but is also invoked by
9150 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9151 to set environment or make variables which specify the build and
9152 host architecture for the package building process.
9157 <sect id="pkg-sourcetree">
9158 <heading>The Debianised source tree</heading>
9161 The source archive scheme described later is intended to
9162 allow a Debianised source tree with some associated control
9163 information to be reproduced and transported easily. The
9164 Debianised source tree is a version of the original program
9165 with certain files added for the benefit of the
9166 Debianisation process, and with any other changes required
9167 made to the rest of the source code and installation
9172 The extra files created for Debian are in the subdirectory
9173 <file>debian</file> of the top level of the Debianised source
9174 tree. They are described below.
9177 <sect1 id="pkg-debianrules">
9178 <heading><file>debian/rules</file> - the main building script</heading>
9181 See <ref id="debianrules">.
9186 <sect1 id="pkg-dpkgchangelog">
9187 <heading><file>debian/changelog</file></heading>
9190 See <ref id="dpkgchangelog">.
9194 It is recommended that the entire changelog be encoded in the
9195 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9197 <url id="http://www.unicode.org/"
9198 name="Unicode">.<footnote>
9200 Support for Unicode, and specifically UTF-8, is
9201 steadily increasing among popular applications in
9202 Debian. For example, in unstable, GNOME 2 has
9203 excellent support (almost level 2) in almost all its
9204 applications; the big remaining one is gnome-terminal,
9205 of which one requires development versions in order to
9206 support UTF-8 (available in Debian experimental now if
9207 you want to play). I think that by the time sarge is
9208 released, UTF-8 support will start to hit critical
9211 I think it is fairly obvious that we need to
9212 eventually transition to UTF-8 for our package
9213 infrastructure; it is really the only sane charset in
9214 an international environment. Now, we can't switch to
9215 using UTF-8 for package control fields and the like
9216 until dpkg has better support, but one thing we can
9217 start doing today is requesting that Debian changelogs
9218 are UTF-8 encoded. At some point in time, we can start
9219 requiring them to do so.
9222 Checking for non-UTF8 characters in a changelog is
9223 trivial. Dump the file through
9224 <example>iconv -f utf-8 -t ucs-4</example>
9225 discard the output, and check the return
9226 value. If there are any characters in the stream
9227 which are invalid UTF-8 sequences, iconv will exit
9228 with an error code; and this will be the case for the
9229 vast majority of other character sets.
9234 <sect2><heading>Defining alternative changelog formats
9238 It is possible to use a different format to the standard
9239 one, by providing a parser for the format you wish to
9244 In order to have <tt>dpkg-parsechangelog</tt> run your
9245 parser, you must include a line within the last 40 lines
9246 of your file matching the Perl regular expression:
9247 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9248 parentheses should be the name of the format. For
9249 example, you might say:
9251 @@@ changelog-format: joebloggs @@@
9253 Changelog format names are non-empty strings of alphanumerics.
9257 If such a line exists then <tt>dpkg-parsechangelog</tt>
9258 will look for the parser as
9259 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9261 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9262 it is an error for it not to find it, or for it not to
9263 be an executable program. The default changelog format
9264 is <tt>dpkg</tt>, and a parser for it is provided with
9265 the <tt>dpkg</tt> package.
9269 The parser will be invoked with the changelog open on
9270 standard input at the start of the file. It should read
9271 the file (it may seek if it wishes) to determine the
9272 information required and return the parsed information
9273 to standard output in the form of a series of control
9274 fields in the standard format. By default it should
9275 return information about only the most recent version in
9276 the changelog; it should accept a
9277 <tt>-v<var>version</var></tt> option to return changes
9278 information from all versions present <em>strictly
9279 after</em> <var>version</var>, and it should then be an
9280 error for <var>version</var> not to be present in the
9286 <list compact="compact">
9287 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9288 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9289 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9290 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9291 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9292 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9293 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9298 If several versions are being returned (due to the use
9299 of <tt>-v</tt>), the urgency value should be of the
9300 highest urgency code listed at the start of any of the
9301 versions requested followed by the concatenated
9302 (space-separated) comments from all the versions
9303 requested; the maintainer, version, distribution and
9304 date should always be from the most recent version.
9308 For the format of the <tt>Changes</tt> field see
9309 <ref id="f-Changes">.
9313 If the changelog format which is being parsed always or
9314 almost always leaves a blank line between individual
9315 change notes these blank lines should be stripped out,
9316 so as to make the resulting output compact.
9320 If the changelog format does not contain date or package
9321 name information this information should be omitted from
9322 the output. The parser should not attempt to synthesise
9323 it or find it from other sources.
9327 If the changelog does not have the expected format the
9328 parser should exit with a nonzero exit status, rather
9329 than trying to muddle through and possibly generating
9334 A changelog parser may not interact with the user at
9340 <sect1 id="pkg-srcsubstvars">
9341 <heading><file>debian/substvars</file> and variable substitutions</heading>
9344 See <ref id="substvars">.
9350 <heading><file>debian/files</file></heading>
9353 See <ref id="debianfiles">.
9357 <sect1><heading><file>debian/tmp</file>
9361 This is the canonical temporary location for the
9362 construction of binary packages by the <tt>binary</tt>
9363 target. The directory <file>tmp</file> serves as the root of
9364 the filesystem tree as it is being constructed (for
9365 example, by using the package's upstream makefiles install
9366 targets and redirecting the output there), and it also
9367 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9368 id="pkg-bincreating">.
9372 If several binary packages are generated from the same
9373 source tree it is usual to use several
9374 <file>debian/tmp<var>something</var></file> directories, for
9375 example <file>tmp-a</file> or <file>tmp-doc</file>.
9379 Whatever <file>tmp</file> directories are created and used by
9380 <tt>binary</tt> must of course be removed by the
9381 <tt>clean</tt> target.</p></sect1>
9385 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9389 As it exists on the FTP site, a Debian source package
9390 consists of three related files. You must have the right
9391 versions of all three to be able to use them.
9396 <tag>Debian source control file - <tt>.dsc</tt></tag>
9398 This file is a control file used by <prgn>dpkg-source</prgn>
9399 to extract a source package.
9400 See <ref id="debiansourcecontrolfiles">.
9404 Original source archive -
9406 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9413 This is a compressed (with <tt>gzip -9</tt>)
9414 <prgn>tar</prgn> file containing the source code from
9415 the upstream authors of the program. The tarfile
9416 unpacks into a directory
9417 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9418 and does not contain files anywhere other than in
9419 there or in its subdirectories.</p>
9423 Debianisation diff -
9425 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9431 This is a unified context diff (<tt>diff -u</tt>)
9432 giving the changes which are required to turn the
9433 original source into the Debian source. These changes
9434 may only include editing and creating plain files.
9435 The permissions of files, the targets of symbolic
9436 links and the characteristics of special files or
9437 pipes may not be changed and no files may be removed
9442 All the directories in the diff must exist, except the
9443 <file>debian</file> subdirectory of the top of the source
9444 tree, which will be created by
9445 <prgn>dpkg-source</prgn> if necessary when unpacking.
9449 The <prgn>dpkg-source</prgn> program will
9450 automatically make the <file>debian/rules</file> file
9451 executable (see below).</p></item>
9456 If there is no original source code - for example, if the
9457 package is specially prepared for Debian or the Debian
9458 maintainer is the same as the upstream maintainer - the
9459 format is slightly different: then there is no diff, and the
9461 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9462 contains a directory
9463 <file><var>package</var>-<var>version</var></file>.
9468 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9471 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9472 Debian source package. However, if it is not available it
9473 is possible to unpack a Debian source archive as follows:
9474 <enumlist compact="compact">
9477 Untar the tarfile, which will create a <file>.orig</file>
9481 <p>Rename the <file>.orig</file> directory to
9482 <file><var>package</var>-<var>version</var></file>.</p>
9486 Create the subdirectory <file>debian</file> at the top of
9487 the source tree.</p>
9489 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9491 <item><p>Untar the tarfile again if you want a copy of the original
9492 source code alongside the Debianised version.</p>
9497 It is not possible to generate a valid Debian source archive
9498 without using <prgn>dpkg-source</prgn>. In particular,
9499 attempting to use <prgn>diff</prgn> directly to generate the
9500 <file>.diff.gz</file> file will not work.
9504 <heading>Restrictions on objects in source packages</heading>
9507 The source package may not contain any hard links
9509 This is not currently detected when building source
9510 packages, but only when extracting
9514 Hard links may be permitted at some point in the
9515 future, but would require a fair amount of
9517 </footnote>, device special files, sockets or setuid or
9520 Setgid directories are allowed.
9525 The source packaging tools manage the changes between the
9526 original and Debianised source using <prgn>diff</prgn> and
9527 <prgn>patch</prgn>. Turning the original source tree as
9528 included in the <file>.orig.tar.gz</file> into the debianised
9529 source must not involve any changes which cannot be
9530 handled by these tools. Problematic changes which cause
9531 <prgn>dpkg-source</prgn> to halt with an error when
9532 building the source package are:
9533 <list compact="compact">
9534 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9536 <item><p>Changing the targets of symbolic links.</p>
9538 <item><p>Creating directories, other than <file>debian</file>.</p>
9540 <item><p>Changes to the contents of binary files.</p></item>
9541 </list> Changes which cause <prgn>dpkg-source</prgn> to
9542 print a warning but continue anyway are:
9543 <list compact="compact">
9546 Removing files, directories or symlinks.
9548 Renaming a file is not treated specially - it is
9549 seen as the removal of the old file (which
9550 generates a warning, but is otherwise ignored),
9551 and the creation of the new one.
9557 Changed text files which are missing the usual final
9558 newline (either in the original or the modified
9563 Changes which are not represented, but which are not detected by
9564 <prgn>dpkg-source</prgn>, are:
9565 <list compact="compact">
9566 <item><p>Changing the permissions of files (other than
9567 <file>debian/rules</file>) and directories.</p></item>
9572 The <file>debian</file> directory and <file>debian/rules</file>
9573 are handled specially by <prgn>dpkg-source</prgn> - before
9574 applying the changes it will create the <file>debian</file>
9575 directory, and afterwards it will make
9576 <file>debian/rules</file> world-exectuable.
9582 <appendix id="pkg-controlfields">
9583 <heading>Control files and their fields (from old Packaging Manual)</heading>
9586 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9587 data in a common format, known as control files. Binary and
9588 source packages have control data as do the <file>.changes</file>
9589 files which control the installation of uploaded files, and
9590 <prgn>dpkg</prgn>'s internal databases are in a similar
9595 <heading>Syntax of control files</heading>
9598 See <ref id="controlsyntax">.
9602 It is important to note that there are several fields which
9603 are optional as far as <prgn>dpkg</prgn> and the related
9604 tools are concerned, but which must appear in every Debian
9605 package, or whose omission may cause problems.
9610 <heading>List of fields</heading>
9613 See <ref id="controlfieldslist">.
9617 This section now contains only the fields that didn't belong
9618 to the Policy manual.
9621 <sect1 id="pkg-f-Filename">
9622 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9625 These fields in <tt>Packages</tt> files give the
9626 filename(s) of (the parts of) a package in the
9627 distribution directories, relative to the root of the
9628 Debian hierarchy. If the package has been split into
9629 several parts the parts are all listed in order, separated
9634 <sect1 id="pkg-f-Size">
9635 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9638 These fields in <file>Packages</file> files give the size (in
9639 bytes, expressed in decimal) and MD5 checksum of the
9640 file(s) which make(s) up a binary package in the
9641 distribution. If the package is split into several parts
9642 the values for the parts are listed in order, separated by
9647 <sect1 id="pkg-f-Status">
9648 <heading><tt>Status</tt></heading>
9651 This field in <prgn>dpkg</prgn>'s status file records
9652 whether the user wants a package installed, removed or
9653 left alone, whether it is broken (requiring
9654 reinstallation) or not and what its current state on the
9655 system is. Each of these pieces of information is a
9660 <sect1 id="pkg-f-Config-Version">
9661 <heading><tt>Config-Version</tt></heading>
9664 If a package is not installed or not configured, this
9665 field in <prgn>dpkg</prgn>'s status file records the last
9666 version of the package which was successfully
9671 <sect1 id="pkg-f-Conffiles">
9672 <heading><tt>Conffiles</tt></heading>
9675 This field in <prgn>dpkg</prgn>'s status file contains
9676 information about the automatically-managed configuration
9677 files held by a package. This field should <em>not</em>
9678 appear anywhere in a package!
9683 <heading>Obsolete fields</heading>
9686 These are still recognised by <prgn>dpkg</prgn> but should
9687 not appear anywhere any more.
9689 <taglist compact="compact">
9691 <tag><tt>Revision</tt></tag>
9692 <tag><tt>Package-Revision</tt></tag>
9693 <tag><tt>Package_Revision</tt></tag>
9695 The Debian revision part of the package version was
9696 at one point in a separate control file field. This
9697 field went through several names.
9700 <tag><tt>Recommended</tt></tag>
9701 <item>Old name for <tt>Recommends</tt>.</item>
9703 <tag><tt>Optional</tt></tag>
9704 <item>Old name for <tt>Suggests</tt>.</item>
9706 <tag><tt>Class</tt></tag>
9707 <item>Old name for <tt>Priority</tt>.</item>
9716 <appendix id="pkg-conffiles">
9717 <heading>Configuration file handling (from old Packaging Manual)</heading>
9720 <prgn>dpkg</prgn> can do a certain amount of automatic
9721 handling of package configuration files.
9725 Whether this mechanism is appropriate depends on a number of
9726 factors, but basically there are two approaches to any
9727 particular configuration file.
9731 The easy method is to ship a best-effort configuration in the
9732 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9733 handle updates. If the user is unlikely to want to edit the
9734 file, but you need them to be able to without losing their
9735 changes, and a new package with a changed version of the file
9736 is only released infrequently, this is a good approach.
9740 The hard method is to build the configuration file from
9741 scratch in the <prgn>postinst</prgn> script, and to take the
9742 responsibility for fixing any mistakes made in earlier
9743 versions of the package automatically. This will be
9744 appropriate if the file is likely to need to be different on
9748 <sect><heading>Automatic handling of configuration files by
9753 A package may contain a control area file called
9754 <tt>conffiles</tt>. This file should be a list of filenames
9755 of configuration files needing automatic handling, separated
9756 by newlines. The filenames should be absolute pathnames,
9757 and the files referred to should actually exist in the
9762 When a package is upgraded <prgn>dpkg</prgn> will process
9763 the configuration files during the configuration stage,
9764 shortly before it runs the package's <prgn>postinst</prgn>
9769 For each file it checks to see whether the version of the
9770 file included in the package is the same as the one that was
9771 included in the last version of the package (the one that is
9772 being upgraded from); it also compares the version currently
9773 installed on the system with the one shipped with the last
9778 If neither the user nor the package maintainer has changed
9779 the file, it is left alone. If one or the other has changed
9780 their version, then the changed version is preferred - i.e.,
9781 if the user edits their file, but the package maintainer
9782 doesn't ship a different version, the user's changes will
9783 stay, silently, but if the maintainer ships a new version
9784 and the user hasn't edited it the new version will be
9785 installed (with an informative message). If both have
9786 changed their version the user is prompted about the problem
9787 and must resolve the differences themselves.
9791 The comparisons are done by calculating the MD5 message
9792 digests of the files, and storing the MD5 of the file as it
9793 was included in the most recent version of the package.
9797 When a package is installed for the first time
9798 <prgn>dpkg</prgn> will install the file that comes with it,
9799 unless that would mean overwriting a file already on the
9804 However, note that <prgn>dpkg</prgn> will <em>not</em>
9805 replace a conffile that was removed by the user (or by a
9806 script). This is necessary because with some programs a
9807 missing file produces an effect hard or impossible to
9808 achieve in another way, so that a missing file needs to be
9809 kept that way if the user did it.
9813 Note that a package should <em>not</em> modify a
9814 <prgn>dpkg</prgn>-handled conffile in its maintainer
9815 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9816 the user confusing and possibly dangerous options for
9817 conffile update when the package is upgraded.</p>
9820 <sect><heading>Fully-featured maintainer script configuration
9825 For files which contain site-specific information such as
9826 the hostname and networking details and so forth, it is
9827 better to create the file in the package's
9828 <prgn>postinst</prgn> script.
9832 This will typically involve examining the state of the rest
9833 of the system to determine values and other information, and
9834 may involve prompting the user for some information which
9835 can't be obtained some other way.
9839 When using this method there are a couple of important
9840 issues which should be considered:
9844 If you discover a bug in the program which generates the
9845 configuration file, or if the format of the file changes
9846 from one version to the next, you will have to arrange for
9847 the postinst script to do something sensible - usually this
9848 will mean editing the installed configuration file to remove
9849 the problem or change the syntax. You will have to do this
9850 very carefully, since the user may have changed the file,
9851 perhaps to fix the very problem that your script is trying
9852 to deal with - you will have to detect these situations and
9853 deal with them correctly.
9857 If you do go down this route it's probably a good idea to
9858 make the program that generates the configuration file(s) a
9859 separate program in <file>/usr/sbin</file>, by convention called
9860 <file><var>package</var>config</file> and then run that if
9861 appropriate from the post-installation script. The
9862 <tt><var>package</var>config</tt> program should not
9863 unquestioningly overwrite an existing configuration - if its
9864 mode of operation is geared towards setting up a package for
9865 the first time (rather than any arbitrary reconfiguration
9866 later) you should have it check whether the configuration
9867 already exists, and require a <tt>--force</tt> flag to
9868 overwrite it.</p></sect>
9871 <appendix id="pkg-alternatives"><heading>Alternative versions of
9872 an interface - <prgn>update-alternatives</prgn> (from old
9877 When several packages all provide different versions of the
9878 same program or file it is useful to have the system select a
9879 default, but to allow the system administrator to change it
9880 and have their decisions respected.
9884 For example, there are several versions of the <prgn>vi</prgn>
9885 editor, and there is no reason to prevent all of them from
9886 being installed at once, each under their own name
9887 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9888 Nevertheless it is desirable to have the name <tt>vi</tt>
9889 refer to something, at least by default.
9893 If all the packages involved cooperate, this can be done with
9894 <prgn>update-alternatives</prgn>.
9898 Each package provides its own version under its own name, and
9899 calls <prgn>update-alternatives</prgn> in its postinst to
9900 register its version (and again in its prerm to deregister
9905 See the manpage <manref name="update-alternatives"
9906 section="8"> for details.
9910 If <prgn>update-alternatives</prgn> does not seem appropriate
9911 you may wish to consider using diversions instead.</p>
9914 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9915 package's version of a file (from old Packaging Manual)
9919 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9920 when it reinstalls the package it belongs to, and to have it
9921 put the file from the package somewhere else instead.
9925 This can be used locally to override a package's version of a
9926 file, or by one package to override another's version (or
9927 provide a wrapper for it).
9931 Before deciding to use a diversion, read <ref
9932 id="pkg-alternatives"> to see if you really want a diversion
9933 rather than several alternative versions of a program.
9937 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9938 and updated by a special program <prgn>dpkg-divert</prgn>.
9939 Please see <manref name="dpkg-divert" section="8"> for full
9940 details of its operation.
9944 When a package wishes to divert a file from another, it should
9945 call <prgn>dpkg-divert</prgn> in its preinst to add the
9946 diversion and rename the existing file. For example,
9947 supposing that a <prgn>smailwrapper</prgn> package wishes to
9948 install a wrapper around <file>/usr/sbin/smail</file>:
9950 if [ install = "$1" ]; then
9951 dpkg-divert --package smailwrapper --add --rename \
9952 --divert /usr/sbin/smail.real /usr/sbin/smail
9954 </example> Testing <tt>$1</tt> is necessary so that the script
9955 doesn't try to add the diversion again when
9956 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
9957 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
9958 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
9959 get installed as the true version.
9963 The postrm has to do the reverse:
9965 if [ remove = "$1" ]; then
9966 dpkg-divert --package smailwrapper --remove --rename \
9967 --divert /usr/sbin/smail.real /usr/sbin/smail
9973 Do not attempt to divert a file which is vitally important for
9974 the system's operation - when using <prgn>dpkg-divert</prgn>
9975 there is a time, after it has been diverted but before
9976 <prgn>dpkg</prgn> has installed the new version, when the file
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