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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 date based portion of the version number
860 should be changed to the following format in such cases:
861 "19960501", "19961224". It is up to the maintainer whether
862 he/she wants to bother the upstream maintainer to change
863 the version numbers upstream, too.
867 Note that other version formats based on dates which are
868 parsed correctly by the package management system should
869 <em>not</em> be changed.
873 Native Debian packages (i.e., packages which have been
874 written especially for Debian) whose version numbers include
875 dates should always use the "YYYYMMDD" format.
882 <heading>The maintainer of a package</heading>
885 Every package must have a Debian maintainer (the
886 maintainer may be one person or a group of people
887 reachable from a common email address, such as a mailing
888 list). The maintainer is responsible for ensuring that
889 the package is placed in the appropriate distributions.
893 The maintainer must be specified in the
894 <tt>Maintainer</tt> control field with their correct name
895 and a working email address. If one person maintains
896 several packages, 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>.
1086 The procedure for updating the list is described in the preface
1093 <heading>Base system</heading>
1096 The <tt>base system</tt> is a minimum subset of the Debian
1097 GNU/Linux system that is installed before everything else
1098 on a new system. Thus, only very few packages are allowed
1099 to go into the <tt>base</tt> section to keep the required
1100 disk usage very small.
1104 Most of these packages will have the priority value
1105 <tt>required</tt> or at least <tt>important</tt>, and many
1106 of them will be tagged <tt>essential</tt> (see below).
1111 <heading>Essential packages</heading>
1114 Some packages are tagged <tt>essential</tt> for a system
1115 using the <tt>Essential</tt> control file field.
1116 The format of the <tt>Essential</tt> control field is
1117 described in <ref id="f-Essential">.
1121 Since these packages cannot be easily removed (one has to
1122 specify an extra <em>force option</em> to
1123 <prgn>dpkg</prgn> to do so), this flag must not be used
1124 unless absolutely necessary. A shared library package
1125 must not be tagged <tt>essential</tt>; dependencies will
1126 prevent its premature removal, and we need to be able to
1127 remove it when it has been superseded.
1131 Since dpkg will not prevent upgrading of other packages
1132 while an <tt>essential</tt> package is in an unconfigured
1133 state, all <tt>essential</tt> packages must supply all of
1134 their core functionality even when unconfigured. If the
1135 package cannot satisfy this requirement it must not be
1136 tagged as essential, and any packages depending on this
1137 package must instead have explicit dependency fields as
1142 You must not tag any packages <tt>essential</tt> before
1143 this has been discussed on the <tt>debian-devel</tt>
1144 mailing list and a consensus about doing that has been
1150 <heading>Tasks</heading>
1153 The Debian install process allows the user to choose from
1154 a number of common tasks which a Debian system can be used to
1155 perform. Selecting a task with <prgn>tasksel</prgn> causes
1156 a set of packages that are useful in performing that task to be
1161 This set of packages is all available packages which have the
1162 name of the selected task in the <tt>Task</tt> field of their
1163 control file. The format of this field is a list of tasks,
1164 separated by commas.
1168 You should not tag any packages as belonging to a task
1169 before this has been discussed on the
1170 <em>debian-devel</em> mailing list and a consensus about
1171 doing that has been reached.
1175 For third parties (and historical reasons), tasksel also
1176 supports constructing tasks based on <em>task
1177 packages</em>. These are packages whose names begin with
1178 <em>task-</em>. Task packages should not be included in the
1183 <sect id="maintscripts">
1184 <heading>Maintainer Scripts</heading>
1187 The package installation scripts should avoid producing
1188 output which is unnecessary for the user to see and
1189 should rely on <prgn>dpkg</prgn> to stave off boredom on
1190 the part of a user installing many packages. This means,
1191 amongst other things, using the <tt>--quiet</tt> option on
1192 <prgn>install-info</prgn>.
1196 Errors which occur during the execution of an installation
1197 script must be checked and the installation must not
1198 continue after an error.
1202 Note that in general <ref id="scripts"> applies to package
1203 maintainer scripts, too.
1207 You should not use <prgn>dpkg-divert</prgn> on a file
1208 belonging to another package without consulting the
1209 maintainer of that package first.
1213 All packages which supply an instance of a common command
1214 name (or, in general, filename) should generally use
1215 <prgn>update-alternatives</prgn>, so that they may be
1216 installed together. If <prgn>update-alternatives</prgn>
1217 is not used, then each package must use
1218 <tt>Conflicts</tt> to ensure that other packages are
1219 de-installed. (In this case, it may be appropriate to
1220 specify a conflict against earlier versions of something
1221 that previously did not use
1222 <prgn>update-alternatives</prgn>; this is an exception to
1223 the usual rule that versioned conflicts should be
1227 <sect1 id="maintscriptprompt">
1228 <heading>Prompting in maintainer scripts</heading>
1230 Package maintainer scripts may prompt the user if
1231 necessary. Prompting should be done by communicating
1232 through a program, such as <prgn>debconf</prgn>, which
1233 conforms to the Debian Configuration management
1234 specification, version 2 or higher. Prompting the user by
1235 other means, such as by hand<footnote>
1236 From the Jargon file: by hand 2. By extension,
1237 writing code which does something in an explicit or
1238 low-level way for which a presupplied library
1239 (<em>debconf, in this instance</em>) routine ought
1240 to have been available.
1241 </footnote>, is now deprecated.
1245 The Debian Configuration management specification is included
1246 in the <file>debconf_specification</file> files in the
1247 <package>debian-policy</package> package.
1248 It is also available from the Debian web mirrors at
1249 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1250 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1254 Packages which use the Debian Configuration management
1255 specification may contain an additional
1256 <prgn>config</prgn> script and a <tt>templates</tt>
1257 file in their control archive<footnote>
1258 The control.tar.gz inside the .deb.
1259 See <manref name="deb" section="5">.
1261 The <prgn>config</prgn> script might be run before the
1262 <prgn>preinst</prgn> script, and before the package is unpacked
1263 or any of its dependencies or pre-dependancies are satisfied.
1264 Therefore it must work using only the tools present in
1265 <em>essential</em> packages.<footnote>
1266 <package>Debconf</package> or another tool that
1267 implements the Debian Configuration management
1268 specification will also be installed, and any
1269 versioned dependencies on it will be satisfied
1270 before preconfiguration begins.
1275 Packages should try to minimize the amount of prompting
1276 they need to do, and they should ensure that the user
1277 will only ever be asked each question once. This means
1278 that packages should try to use appropriate shared
1279 configuration files (such as <file>/etc/papersize</file> and
1280 <file>/etc/news/server</file>), and shared
1281 <package>debconf</package> variables rather than each
1282 prompting for their own list of required pieces of
1287 It also means that an upgrade should not ask the same
1288 questions again, unless the user has used
1289 <tt>dpkg --purge</tt> to remove the package's configuration.
1290 The answers to configuration questions should be stored in an
1291 appropriate place in <file>/etc</file> so that the user can
1292 modify them, and how this has been done should be
1297 If a package has a vitally important piece of
1298 information to pass to the user (such as "don't run me
1299 as I am, you must edit the following configuration files
1300 first or you risk your system emitting badly-formatted
1301 messages"), it should display this in the
1302 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1303 prompt the user to hit return to acknowledge the
1304 message. Copyright messages do not count as vitally
1305 important (they belong in
1306 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1307 neither do instructions on how to use a program (these
1308 should be in on-line documentation, where all the users
1313 Any necessary prompting should almost always be confined
1314 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1315 script. If it is done in the <prgn>postinst</prgn>, it
1316 should be protected with a conditional so that
1317 unnecessary prompting doesn't happen if a package's
1318 installation fails and the <prgn>postinst</prgn> is
1319 called with <tt>abort-upgrade</tt>,
1320 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1330 <heading>Source packages</heading>
1332 <sect id="standardsversion">
1333 <heading>Standards conformance</heading>
1336 Source packages should specify the most recent version number
1337 of this policy document with which your package complied
1338 when it was last updated.
1342 This information may be used to file bug reports
1343 automatically if your package becomes too much out of date.
1347 The version is specified in the <tt>Standards-Version</tt>
1349 The format of the <tt>Standards-Version</tt> field is
1350 described in <ref id="f-Standards-Version">.
1354 You should regularly, and especially if your package has
1355 become out of date, check for the newest Policy Manual
1356 available and update your package, if necessary. When your
1357 package complies with the new standards you should update the
1358 <tt>Standards-Version</tt> source package field and
1359 release it.<footnote>
1360 See the file <file>upgrading-checklist</file> for
1361 information about policy which has changed between
1362 different versions of this document.
1368 <sect id="pkg-relations">
1369 <heading>Package relationships</heading>
1372 Source packages should specify which binary packages they
1373 require to be installed or not to be installed in order to
1374 build correctly. For example, if building a package
1375 requires a certain compiler, then the compiler should be
1376 specified as a build-time dependency.
1380 It is not necessary to explicitly specify build-time
1381 relationships on a minimal set of packages that are always
1382 needed to compile, link and put in a Debian package a
1383 standard "Hello World!" program written in C or C++. The
1384 required packages are called <em>build-essential</em>, and
1385 an informational list can be found in
1386 <file>/usr/share/doc/build-essential/list</file> (which is
1387 contained in the <tt>build-essential</tt>
1390 <list compact="compact">
1392 This allows maintaining the list separately
1393 from the policy documents (the list does not
1394 need the kind of control that the policy
1398 Having a separate package allows one to install
1399 the build-essential packages on a machine, as
1400 well as allowing other packages such as tasks to
1401 require installation of the build-essential
1402 packages using the depends relation.
1405 The separate package allows bug reports against
1406 the list to be categorized separately from
1407 the policy management process in the BTS.
1414 When specifying the set of build-time dependencies, one
1415 should list only those packages explicitly required by the
1416 build. It is not necessary to list packages which are
1417 required merely because some other package in the list of
1418 build-time dependencies depends on them.<footnote>
1419 The reason for this is that dependencies change, and
1420 you should list all those packages, and <em>only</em>
1421 those packages that <em>you</em> need directly. What
1422 others need is their business. For example, if you
1423 only link against <file>libimlib</file>, you will need to
1424 build-depend on <package>libimlib2-dev</package> but
1425 not against any <tt>libjpeg*</tt> packages, even
1426 though <tt>libimlib2-dev</tt> currently depends on
1427 them: installation of <package>libimlib2-dev</package>
1428 will automatically ensure that all of its run-time
1429 dependencies are satisfied.
1434 If build-time dependencies are specified, it must be
1435 possible to build the package and produce working binaries
1436 on a system with only essential and build-essential
1437 packages installed and also those required to satisfy the
1438 build-time relationships (including any implied
1439 relationships). In particular, this means that version
1440 clauses should be used rigorously in build-time
1441 relationships so that one cannot produce bad or
1442 inconsistently configured packages when the relationships
1443 are properly satisfied.
1447 <ref id="relationships"> explains the technical details.
1452 <heading>Changes to the upstream sources</heading>
1455 If changes to the source code are made that are not
1456 specific to the needs of the Debian system, they should be
1457 sent to the upstream authors in whatever form they prefer
1458 so as to be included in the upstream version of the
1463 If you need to configure the package differently for
1464 Debian or for Linux, and the upstream source doesn't
1465 provide a way to do so, you should add such configuration
1466 facilities (for example, a new <prgn>autoconf</prgn> test
1467 or <tt>#define</tt>) and send the patch to the upstream
1468 authors, with the default set to the way they originally
1469 had it. You can then easily override the default in your
1470 <file>debian/rules</file> or wherever is appropriate.
1474 You should make sure that the <prgn>configure</prgn> utility
1475 detects the correct architecture specification string
1476 (refer to <ref id="arch-spec"> for details).
1480 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1481 <prgn>configure</prgn> scripts are used, you should edit the
1482 <file>.in</file> files rather than editing the
1483 <prgn>Makefile</prgn> directly. This allows the user to
1484 reconfigure the package if necessary. You should
1485 <em>not</em> configure the package and edit the generated
1486 <prgn>Makefile</prgn>! This makes it impossible for someone
1487 else to later reconfigure the package without losing the
1493 <sect id="dpkgchangelog">
1494 <heading>Debian changelog: <file>debian/changelog</file></heading>
1497 Changes in the Debian version of the package should be
1498 briefly explained in the Debian changelog file
1499 <file>debian/changelog</file>. This includes modifications
1500 made in the Debian package compared to the upstream one
1501 as well as other changes and updates to the package.
1503 Although there is nothing stopping an author who is also
1504 the Debian maintainer from using this changelog for all
1505 their changes, it will have to be renamed if the Debian
1506 and upstream maintainers become different people. In such
1507 a case, however, it might be better to maintain the package
1508 as a non-native package.
1513 Mistakes in changelogs are usually best rectified by making
1514 a new changelog entry rather than "rewriting history" by
1515 editing old changelog entries.
1519 The format of the <file>debian/changelog</file> allows the
1520 package building tools to discover which version of the package
1521 is being built and find out other release-specific information.
1525 That format is a series of entries like this:
1527 <example compact="compact">
1528 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1530 [optional blank line(s), stripped]
1532 * <var>change details</var>
1533 <var>more change details</var>
1535 [blank line(s), included in output of dpkg-parsechangelog]
1537 * <var>even more change details</var>
1539 [optional blank line(s), stripped]
1541 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1546 <var>package</var> and <var>version</var> are the source
1547 package name and version number.
1551 <var>distribution(s)</var> lists the distributions where
1552 this version should be installed when it is uploaded - it
1553 is copied to the <tt>Distribution</tt> field in the
1554 <file>.changes</file> file. See <ref id="f-Distribution">.
1558 <var>urgency</var> is the value for the <tt>Urgency</tt>
1559 field in the <file>.changes</file> file for the upload
1560 (see <ref id="f-Urgency">). It is not possible to specify
1561 an urgency containing commas; commas are used to separate
1562 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1563 <prgn>dpkg</prgn> changelog format (though there is
1564 currently only one useful <var>keyword</var>,
1565 <tt>urgency</tt>).<footnote>
1566 Recognised urgency values are <tt>low</tt>,
1567 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1568 They have an effect on how quickly a package will be
1569 considered for inclusion into the <tt>testing</tt>
1570 distribution, and give an indication of the importance
1571 of any fixes included in this upload.
1576 The change details may in fact be any series of lines
1577 starting with at least two spaces, but conventionally each
1578 change starts with an asterisk and a separating space and
1579 continuation lines are indented so as to bring them in
1580 line with the start of the text above. Blank lines may be
1581 used here to separate groups of changes, if desired.
1585 If this upload resolves bugs recorded in the Bug Tracking
1586 System (BTS), they may be automatically closed on the
1587 inclusion of this package into the Debian archive by
1588 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1589 in the change details.<footnote>
1590 To be precise, the string should match the following
1591 Perl regular expression:
1593 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1595 Then all of the bug numbers listed will be closed by the
1596 archive maintenance script (<prgn>katie</prgn>), or in
1597 the case of an NMU, marked as fixed.
1599 This information is conveyed via the <tt>Closes</tt> field
1600 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1604 The maintainer name and email address used in the changelog
1605 should be the details of the person uploading <em>this</em>
1606 version. They are <em>not</em> necessarily those of the
1607 usual package maintainer. The information here will be
1608 copied to the <tt>Changed-By</tt> field in the
1609 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1610 and then later used to send an acknowledgement when the
1611 upload has been installed.
1615 The <var>date</var> should be in RFC822 format<footnote>
1616 This is generated by the <prgn>822-date</prgn>
1618 </footnote>; it should include the time zone specified
1619 numerically, with the time zone name or abbreviation
1620 optionally present as a comment in parentheses.
1624 The first "title" line with the package name should start
1625 at the left hand margin; the "trailer" line with the
1626 maintainer and date details should be preceded by exactly
1627 one space. The maintainer details and the date must be
1628 separated by exactly two spaces.
1632 For more information on placement of the changelog files
1633 within binary packages, please see <ref id="changelogs">.
1636 <sect1><heading>Alternative changelog formats</heading>
1639 In non-experimental packages you must use a format for
1640 <file>debian/changelog</file> which is supported by the most
1641 recent released version of <prgn>dpkg</prgn>.
1645 It is possible to use a format different from the standard
1646 one by providing a changelog parser for the format you wish
1647 to use. The parser must have an API compatible with that
1648 expected by <prgn>dpkg-genchanges</prgn> and
1649 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1652 If there is general interest in the new format, you should
1653 contact the <package>dpkg</package> maintainer to have the
1654 parser script for it included in the <prgn>dpkg</prgn>
1655 package. (You will need to agree that the parser and its
1656 man page may be distributed under the GNU GPL, just as the rest
1657 of <prgn>dpkg</prgn> is.)
1664 <heading>Error trapping in makefiles</heading>
1667 When <prgn>make</prgn> invokes a command in a makefile
1668 (including your package's upstream makefiles and
1669 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1670 means that <prgn>sh</prgn>'s usual bad error handling
1671 properties apply: if you include a miniature script as one
1672 of the commands in your makefile you'll find that if you
1673 don't do anything about it then errors are not detected
1674 and <prgn>make</prgn> will blithely continue after
1679 Every time you put more than one shell command (this
1680 includes using a loop) in a makefile command you
1681 must make sure that errors are trapped. For
1682 simple compound commands, such as changing directory and
1683 then running a program, using <tt>&&</tt> rather
1684 than semicolon as a command separator is sufficient. For
1685 more complex commands including most loops and
1686 conditionals you should include a separate <tt>set -e</tt>
1687 command at the start of every makefile command that's
1688 actually one of these miniature shell scripts.
1692 <sect id="timestamps">
1693 <heading>Time Stamps</heading>
1695 Maintainers should preserve the modification times of the
1696 upstream source files in a package, as far as is reasonably
1698 The rationale is that there is some information conveyed
1699 by knowing the age of the file, for example, you could
1700 recognize that some documentation is very old by looking
1701 at the modification time, so it would be nice if the
1702 modification time of the upstream source would be
1708 <sect id="restrictions">
1709 <heading>Restrictions on objects in source packages</heading>
1712 The source package may not contain any hard links<footnote>
1714 This is not currently detected when building source
1715 packages, but only when extracting
1719 Hard links may be permitted at some point in the
1720 future, but would require a fair amount of
1723 </footnote>, device special files, sockets or setuid or
1724 setgid files.<footnote>
1725 Setgid directories are allowed.
1730 <sect id="debianrules">
1731 <heading>Main building script: <file>debian/rules</file></heading>
1734 This file must be an executable makefile, and contains the
1735 package-specific recipes for compiling the package and
1736 building binary package(s) from the source.
1740 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1741 so that it can be invoked by saying its name rather than
1742 invoking <prgn>make</prgn> explicitly.
1746 Since an interactive <file>debian/rules</file> script makes it
1747 impossible to auto-compile that package and also makes it
1748 hard for other people to reproduce the same binary
1749 package, all <em>required targets</em> MUST be
1750 non-interactive. At a minimum, required targets are the
1751 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1752 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1753 <em>binary-indep</em>, and <em>build</em>. It also follows
1754 that any target that these targets depend on must also be
1759 The targets are as follows (required unless stated otherwise):
1761 <tag><tt>build</tt></tag>
1764 The <tt>build</tt> target should perform all the
1765 configuration and compilation of the package.
1766 If a package has an interactive pre-build
1767 configuration routine, the Debianized source package
1768 must either be built after this has taken place (so
1769 that the binary package can be built without rerunning
1770 the configuration) or the configuration routine
1771 modified to become non-interactive. (The latter is
1772 preferable if there are architecture-specific features
1773 detected by the configuration routine.)
1777 For some packages, notably ones where the same
1778 source tree is compiled in different ways to produce
1779 two binary packages, the <tt>build</tt> target
1780 does not make much sense. For these packages it is
1781 good enough to provide two (or more) targets
1782 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1783 for each of the ways of building the package, and a
1784 <tt>build</tt> target that does nothing. The
1785 <tt>binary</tt> target will have to build the
1786 package in each of the possible ways and make the
1787 binary package out of each.
1791 The <tt>build</tt> target must not do anything
1792 that might require root privilege.
1796 The <tt>build</tt> target may need to run the
1797 <tt>clean</tt> target first - see below.
1801 When a package has a configuration and build routine
1802 which takes a long time, or when the makefiles are
1803 poorly designed, or when <tt>build</tt> needs to
1804 run <tt>clean</tt> first, it is a good idea to
1805 <tt>touch build</tt> when the build process is
1806 complete. This will ensure that if <tt>debian/rules
1807 build</tt> is run again it will not rebuild the whole
1809 Another common way to do this is for <tt>build</tt>
1810 to depend on <prgn>build-stamp</prgn> and to do
1811 nothing else, and for the <prgn>build-stamp</prgn>
1812 target to do the building and to <tt>touch
1813 build-stamp</tt> on completion. This is
1814 especially useful if the build routine creates a
1815 file or directory called <tt>build</tt>; in such a
1816 case, <tt>build</tt> will need to be listed as
1817 a phony target (i.e., as a dependency of the
1818 <tt>.PHONY</tt> target). See the documentation of
1819 <prgn>make</prgn> for more information on phony
1825 <tag><tt>build-arch</tt> (optional),
1826 <tt>build-indep</tt> (optional)
1830 A package may also provide both of the targets
1831 <tt>build-arch</tt> and <tt>build-indep</tt>.
1832 The <tt>build-arch</tt> target, if provided, should
1833 perform all the configuration and compilation required
1834 for producing all architecture-dependant binary packages
1835 (those packages for which the body of the
1836 <tt>Architecture</tt> field in <tt>debian/control</tt>
1837 is not <tt>all</tt>).
1838 Similarly, the <tt>build-indep</tt> target, if
1839 provided, should perform all the configuration and
1840 compilation required for producing all
1841 architecture-independent binary packages
1842 (those packages for which the body of the
1843 <tt>Architecture</tt> field in <tt>debian/control</tt>
1845 The <tt>build</tt> target should depend on those of the
1846 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1847 are provided in the rules file.
1851 If one or both of the targets <tt>build-arch</tt> and
1852 <tt>build-indep</tt> are not provided, then invoking
1853 <file>debian/rules</file> with one of the not-provided
1854 targets as arguments should produce a exit status code
1855 of 2. Usually this is provided automatically by make
1856 if the target is missing.
1860 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1861 must not do anything that might require root privilege.
1865 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1866 <tt>binary-indep</tt>
1870 The <tt>binary</tt> target must be all that is
1871 necessary for the user to build the binary package(s)
1872 produced from this source package. It is
1873 split into two parts: <prgn>binary-arch</prgn> builds
1874 the binary packages which are specific to a particular
1875 architecture, and <tt>binary-indep</tt> builds
1876 those which are not.
1879 <tt>binary</tt> may be (and commonly is) a target with
1880 no commands which simply depends on
1881 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1884 Both <tt>binary-*</tt> targets should depend on the
1885 <tt>build</tt> target, or on the appropriate
1886 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1887 provided, so that the package is built if it has not
1888 been already. It should then create the relevant
1889 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1890 make their control files and <prgn>dpkg-deb</prgn> to
1891 build them and place them in the parent of the top
1896 Both the <tt>binary-arch</tt> and
1897 <tt>binary-indep</tt> targets <em>must</em> exist.
1898 If one of them has nothing to do (which will always be
1899 the case if the source generates only a single binary
1900 package, whether architecture-dependent or not), it
1901 must still exist and must always succeed.
1905 The <tt>binary</tt> targets must be invoked as
1907 The <prgn>fakeroot</prgn> package often allows one
1908 to build a package correctly even without being
1914 <tag><tt>clean</tt></tag>
1917 This must undo any effects that the <tt>build</tt>
1918 and <tt>binary</tt> targets may have had, except
1919 that it should leave alone any output files created in
1920 the parent directory by a run of a <tt>binary</tt>
1925 If a <tt>build</tt> file is touched at the end of
1926 the <tt>build</tt> target, as suggested above, it
1927 should be removed as the first action that
1928 <tt>clean</tt> performs, so that running
1929 <tt>build</tt> again after an interrupted
1930 <tt>clean</tt> doesn't think that everything is
1935 The <tt>clean</tt> target may need to be
1936 invoked as root if <tt>binary</tt> has been
1937 invoked since the last <tt>clean</tt>, or if
1938 <tt>build</tt> has been invoked as root (since
1939 <tt>build</tt> may create directories, for
1944 <tag><tt>get-orig-source</tt> (optional)</tag>
1947 This target fetches the most recent version of the
1948 original source package from a canonical archive site
1949 (via FTP or WWW, for example), does any necessary
1950 rearrangement to turn it into the original source
1951 tar file format described below, and leaves it in the
1956 This target may be invoked in any directory, and
1957 should take care to clean up any temporary files it
1962 This target is optional, but providing it if
1963 possible is a good idea.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1997 specification string)
2000 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2001 <tt>DEB_*_GNU_TYPE</tt>)
2004 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2005 <tt>DEB_*_GNU_TYPE</tt>)
2007 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2008 the build machine or <tt>HOST</tt> for specification of the
2013 Backward compatibility can be provided in the rules file
2014 by setting the needed variables to suitable default
2015 values; please refer to the documentation of
2016 <prgn>dpkg-architecture</prgn> for details.
2020 It is important to understand that the <tt>DEB_*_ARCH</tt>
2021 string only determines which Debian architecture we are
2022 building on or for. It should not be used to get the CPU
2023 or system information; the GNU style variables should be
2028 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2029 <sect id="substvars">
2030 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2033 When <prgn>dpkg-gencontrol</prgn>,
2034 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2035 generate control files they perform variable substitutions
2036 on their output just before writing it. Variable
2037 substitutions have the form <tt>${<var>variable</var>}</tt>.
2038 The optional file <file>debian/substvars</file> contains
2039 variable substitutions to be used; variables can also be set
2040 directly from <file>debian/rules</file> using the <tt>-V</tt>
2041 option to the source packaging commands, and certain
2042 predefined variables are also available.
2046 The <file>debian/substvars</file> file is usually generated and
2047 modified dynamically by <file>debian/rules</file> targets, in
2048 which case it must be removed by the <tt>clean</tt> target.
2052 See <manref name="dpkg-source" section="1"> for full
2053 details about source variable substitutions, including the
2054 format of <file>debian/substvars</file>.</p>
2057 <sect id="debianfiles">
2058 <heading>Generated files list: <file>debian/files</file></heading>
2061 This file is not a permanent part of the source tree; it
2062 is used while building packages to record which files are
2063 being generated. <prgn>dpkg-genchanges</prgn> uses it
2064 when it generates a <file>.changes</file> file.
2068 It should not exist in a shipped source package, and so it
2069 (and any backup files or temporary files such as
2070 <file>files.new</file><footnote>
2071 <file>files.new</file> is used as a temporary file by
2072 <prgn>dpkg-gencontrol</prgn> and
2073 <prgn>dpkg-distaddfile</prgn> - they write a new
2074 version of <tt>files</tt> here before renaming it,
2075 to avoid leaving a corrupted copy if an error
2077 </footnote>) should be removed by the
2078 <tt>clean</tt> target. It may also be wise to
2079 ensure a fresh start by emptying or removing it at the
2080 start of the <tt>binary</tt> target.
2084 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2085 package, it adds an entry to <file>debian/files</file> for the
2086 <file>.deb</file> file that will be created when <tt>dpkg-deb
2087 --build</tt> is run for that binary package. So for most
2088 packages all that needs to be done with this file is to
2089 delete it in the <tt>clean</tt> target.
2093 If a package upload includes files besides the source
2094 package and any binary packages whose control files were
2095 made with <prgn>dpkg-gencontrol</prgn> then they should be
2096 placed in the parent of the package's top-level directory
2097 and <prgn>dpkg-distaddfile</prgn> should be called to add
2098 the file to the list in <file>debian/files</file>.</p>
2104 <chapt id="controlfields">
2105 <heading>Control files and their fields</heading>
2108 The package management system manipulates data represented in
2109 a common format, known as <em>control data</em>, stored in
2110 <em>control files</em>.
2111 Control files are used for source packages, binary packages and
2112 the <file>.changes</file> files which control the installation
2113 of uploaded files<footnote>
2114 <prgn>dpkg</prgn>'s internal databases are in a similar
2119 <sect id="controlsyntax">
2120 <heading>Syntax of control files</heading>
2123 A control file consists of one or more paragraphs of
2125 The paragraphs are also sometimes referred to as stanzas.
2127 The paragraphs are separated by blank lines. Some control
2128 files allow only one paragraph; others allow several, in
2129 which case each paragraph usually refers to a different
2130 package. (For example, in source packages, the first
2131 paragraph refers to the source package, and later paragraphs
2132 refer to binary packages generated from the source.)
2136 Each paragraph consists of a series of data fields; each
2137 field consists of the field name, followed by a colon and
2138 then the data/value associated with that field. It ends at
2139 the end of the line. Horizontal whitespace (spaces and
2140 tabs) may occur immediately before or after the value and is
2141 ignored there; it is conventional to put a single space
2142 after the colon. For example, a field might be:
2143 <example compact="compact">
2146 the field name is <tt>Package</tt> and the field value
2151 Some fields' values may span several lines; in this case
2152 each continuation line must start with a space or a tab.
2153 Any trailing spaces or tabs at the end of individual
2154 lines of a field value are ignored.
2158 Except where otherwise stated, only a single line of data is
2159 allowed and whitespace is not significant in a field body.
2160 Whitespace must not appear inside names (of packages,
2161 architectures, files or anything else) or version numbers,
2162 or between the characters of multi-character version
2167 Field names are not case-sensitive, but it is usual to
2168 capitalize the field names using mixed case as shown below.
2172 Blank lines, or lines consisting only of spaces and tabs,
2173 are not allowed within field values or between fields - that
2174 would mean a new paragraph.
2179 <sect id="sourcecontrolfiles">
2180 <heading>Source package control files -- <file>debian/control</file></heading>
2183 The <file>debian/control</file> file contains the most vital
2184 (and version-independent) information about the source package
2185 and about the binary packages it creates.
2189 The first paragraph of the control file contains information about
2190 the source package in general. The subsequent sets each describe a
2191 binary package that the source tree builds.
2195 The fields in the general paragraph (the first one, for the source
2198 <list compact="compact">
2199 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2200 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2201 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2202 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2203 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2204 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2209 The fields in the binary package paragraphs are:
2211 <list compact="compact">
2212 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2213 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2214 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2215 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2216 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2217 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2218 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2223 The syntax and semantics of the fields are described below.
2229 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2230 generate control files for binary packages (see below), by
2231 <prgn>dpkg-genchanges</prgn> to generate the
2232 <tt>.changes</tt> file to accompany the upload, and by
2233 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2234 source control file as part of a source archive.
2238 The fields here may contain variable references - their
2239 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2240 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2241 when they generate output control files.
2242 See <ref id="substvars"> for details.
2247 <sect id="binarycontrolfiles">
2248 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2251 The <file>DEBIAN/control</file> file contains the most vital
2252 (and version-dependent) information about a binary package.
2256 The fields in this file are:
2258 <list compact="compact">
2259 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2260 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2261 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2262 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2263 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2264 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2265 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2266 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2267 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2268 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2269 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2274 <sect id="debiansourcecontrolfiles">
2275 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2278 This file contains a series of fields, identified and
2279 separated just like the fields in the control file of
2280 a binary package. The fields are listed below; their
2281 syntax is described above, in <ref id="pkg-controlfields">.
2283 <list compact="compact">
2284 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2285 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2286 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2287 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2288 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2289 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2290 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2291 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2292 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2297 The source package control file is generated by
2298 <prgn>dpkg-source</prgn> when it builds the source
2299 archive, from other files in the source package,
2300 described above. When unpacking, it is checked against
2301 the files and directories in the other parts of the
2307 <sect id="debianchangesfiles">
2308 <heading>Debian changes files -- <file>.changes</file></heading>
2311 The .changes files are used by the Debian archive maintenance
2312 software to process updates to packages. They contain one
2313 paragraph which contains information from the
2314 <tt>debian/control</tt> file and other data about the
2315 source package gathered via <tt>debian/changelog</tt>
2316 and <tt>debian/rules</tt>.
2320 The fields in this file are:
2322 <list compact="compact">
2323 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2324 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2325 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2326 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2327 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2328 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2329 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2330 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2331 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2332 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2333 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2335 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2341 <sect id="controlfieldslist">
2342 <heading>List of fields</heading>
2344 <sect1 id="f-Source">
2345 <heading><tt>Source</tt></heading>
2348 This field identifies the source package name.
2352 In a main source control information, a <file>.changes</file>
2353 or a <file>.dsc</file> file this may contain only the name
2354 of the source package.
2358 In the control file of a binary package it may be followed
2359 by a version number in parentheses<footnote>
2360 It is customary to leave a space after the package name
2361 if a version number is specified.
2363 This version number may be omitted (and is, by
2364 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2365 the <tt>Version</tt> field of the binary package in
2366 question. The field itself may be omitted from a binary
2367 package control file when the source package has the same
2368 name and version as the binary package.
2372 <sect1 id="f-Maintainer">
2373 <heading><tt>Maintainer</tt></heading>
2376 The package maintainer's name and email address. The name
2377 should come first, then the email address inside angle
2378 brackets <tt><></tt> (in RFC822 format).
2382 If the maintainer's name contains a full stop then the
2383 whole field will not work directly as an email address due
2384 to a misfeature in the syntax specified in RFC822; a
2385 program using this field as an address must check for this
2386 and correct the problem if necessary (for example by
2387 putting the name in round brackets and moving it to the
2388 end, and bringing the email address forward).
2392 <sect1 id="f-Changed-By">
2393 <heading><tt>Changed-By</tt></heading>
2396 The name and email address of the person who changed the
2397 said package. Usually the name of the maintainer.
2398 All the rules for the Maintainer field apply here, too.
2402 <sect1 id="f-Section">
2403 <heading><tt>Section</tt></heading>
2406 This field specifies an application area into which the package
2407 has been classified. See <ref id="subsections">.
2411 When it appears in the <file>debian/control</file> file,
2412 it gives the value for the subfield of the same name in
2413 the <tt>Files</tt> field of the <file>.changes</file> file.
2414 It also gives the default for the same field in the binary
2419 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2420 field in the control file of a binary package - use the
2421 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2425 <sect1 id="f-Priority">
2426 <heading><tt>Priority</tt></heading>
2429 This field represents how important that it is that the user
2430 have the package installed. See <ref id="priorities">.
2434 When it appears in the <file>debian/control</file> file,
2435 it gives the value for the subfield of the same name in
2436 the <tt>Files</tt> field of the <file>.changes</file> file.
2437 It also gives the default for the same field in the binary
2442 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2443 field in the control file of a binary package - use the
2444 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2448 <sect1 id="f-Package">
2449 <heading><tt>Package</tt></heading>
2452 The name of the binary package.
2456 Package names must consist only of lower case letters
2457 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2458 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2459 They must be at least two characters long and must start
2460 with an alphanumeric character.
2464 <sect1 id="f-Architecture">
2465 <heading><tt>Architecture</tt></heading>
2468 Depending on context and the control file used, the
2469 <tt>Architecture</tt> field can include the following sets of
2472 <item>A unique single word identifying a Debian machine
2473 architecture, see <ref id="arch-spec">.
2474 <item><tt>all</tt>, which indicates an
2475 architecture-independent package.
2476 <item><tt>any</tt>, which indicates a package available
2477 for building on any architecture.
2478 <item><tt>source</tt>, which indicates a source package.
2483 In the main <file>debian/control</file> file in the source
2484 package, or in the source package control file
2485 <file>.dsc</file>, one may specify a list of architectures
2486 separated by spaces, or the special values <tt>any</tt> or
2491 Specifying <tt>any</tt> indicates that the source package
2492 isn't dependent on any particular architecture and should
2493 compile fine on any one. The produced binary package(s)
2494 will be specific to whatever the current build architecture
2496 This is the most often used setting, and is recommended
2497 for new packages that aren't <tt>Architecture: all</tt>.
2502 Specifying a list of architectures indicates that the source
2503 will build an architecture-dependent package, and will only
2504 work correctly on the listed architectures.<footnote>
2505 This is a setting used for a minority of cases where the
2506 program is not portable. Generally, it should not be used
2512 In a <file>.changes</file> file, the <tt>Architecture</tt>
2513 field lists the architecture(s) of the package(s)
2514 currently being uploaded. This will be a list; if the
2515 source for the package is also being uploaded, the special
2516 entry <tt>source</tt> is also present.
2520 See <ref id="debianrules"> for information how to get the
2521 architecture for the build process.
2525 <sect1 id="f-Essential">
2526 <heading><tt>Essential</tt></heading>
2529 This is a boolean field which may occur only in the
2530 control file of a binary package or in a per-package fields
2531 paragraph of a main source control data file.
2535 If set to <tt>yes</tt> then the package management system
2536 will refuse to remove the package (upgrading and replacing
2537 it is still possible). The other possible value is <tt>no</tt>,
2538 which is the same as not having the field at all.
2543 <heading>Package interrelationship fields:
2544 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2545 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2546 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2550 These fields describe the package's relationships with
2551 other packages. Their syntax and semantics are described
2552 in <ref id="relationships">.</p>
2555 <sect1 id="f-Standards-Version">
2556 <heading><tt>Standards-Version</tt></heading>
2559 The most recent version of the standards (the policy
2560 manual and associated texts) with which the package
2565 The version number has four components: major and minor
2566 version number and major and minor patch level. When the
2567 standards change in a way that requires every package to
2568 change the major number will be changed. Significant
2569 changes that will require work in many packages will be
2570 signaled by a change to the minor number. The major patch
2571 level will be changed for any change to the meaning of the
2572 standards, however small; the minor patch level will be
2573 changed when only cosmetic, typographical or other edits
2574 are made which neither change the meaning of the document
2575 nor affect the contents of packages.
2579 Thus only the first three components of the policy version
2580 are significant in the <em>Standards-Version</em> control
2581 field, and so either these three components or the all
2582 four components may be specified.<footnote>
2583 In the past, people specified the full version number
2584 in the Standards-Version field, for example "2.3.0.0".
2585 Since minor patch-level changes don't introduce new
2586 policy, it was thought it would be better to relax
2587 policy and only require the first 3 components to be
2588 specified, in this example "2.3.0". All four
2589 components may still be used if someone wishes to do so.
2595 <sect1 id="f-Version">
2596 <heading><tt>Version</tt></heading>
2599 The version number of a package. The format is:
2600 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2604 The three components here are:
2606 <tag><var>epoch</var></tag>
2609 This is a single (generally small) unsigned integer. It
2610 may be omitted, in which case zero is assumed. If it is
2611 omitted then the <var>upstream_version</var> may not
2616 It is provided to allow mistakes in the version numbers
2617 of older versions of a package, and also a package's
2618 previous version numbering schemes, to be left behind.
2622 <tag><var>upstream_version</var></tag>
2625 This is the main part of the version number. It is
2626 usually the version number of the original ("upstream")
2627 package from which the <file>.deb</file> file has been made,
2628 if this is applicable. Usually this will be in the same
2629 format as that specified by the upstream author(s);
2630 however, it may need to be reformatted to fit into the
2631 package management system's format and comparison
2636 The comparison behavior of the package management system
2637 with respect to the <var>upstream_version</var> is
2638 described below. The <var>upstream_version</var>
2639 portion of the version number is mandatory.
2643 The <var>upstream_version</var> may contain only
2644 alphanumerics<footnote>
2645 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2647 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2648 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2649 start with a digit. If there is no
2650 <var>debian_revision</var> then hyphens are not allowed;
2651 if there is no <var>epoch</var> then colons are not
2656 <tag><var>debian_revision</var></tag>
2659 This part of the version number specifies the version of
2660 the Debian package based on the upstream version. It
2661 may contain only alphanumerics and the characters
2662 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2663 compared in the same way as the
2664 <var>upstream_version</var> is.
2668 It is optional; if it isn't present then the
2669 <var>upstream_version</var> may not contain a hyphen.
2670 This format represents the case where a piece of
2671 software was written specifically to be turned into a
2672 Debian package, and so there is only one "debianization"
2673 of it and therefore no revision indication is required.
2677 It is conventional to restart the
2678 <var>debian_revision</var> at <tt>1</tt> each time the
2679 <var>upstream_version</var> is increased.
2683 The package management system will break the version
2684 number apart at the last hyphen in the string (if there
2685 is one) to determine the <var>upstream_version</var> and
2686 <var>debian_revision</var>. The absence of a
2687 <var>debian_revision</var> compares earlier than the
2688 presence of one (but note that the
2689 <var>debian_revision</var> is the least significant part
2690 of the version number).
2697 The <var>upstream_version</var> and <var>debian_revision</var>
2698 parts are compared by the package management system using the
2703 The strings are compared from left to right.
2707 First the initial part of each string consisting entirely of
2708 non-digit characters is determined. These two parts (one of
2709 which may be empty) are compared lexically. If a difference
2710 is found it is returned. The lexical comparison is a
2711 comparison of ASCII values modified so that all the letters
2712 sort earlier than all the non-letters.
2716 Then the initial part of the remainder of each string which
2717 consists entirely of digit characters is determined. The
2718 numerical values of these two parts are compared, and any
2719 difference found is returned as the result of the comparison.
2720 For these purposes an empty string (which can only occur at
2721 the end of one or both version strings being compared) counts
2726 These two steps (comparing and removing initial non-digit
2727 strings and initial digit strings) are repeated until a
2728 difference is found or both strings are exhausted.
2732 Note that the purpose of epochs is to allow us to leave behind
2733 mistakes in version numbering, and to cope with situations
2734 where the version numbering scheme changes. It is
2735 <em>not</em> intended to cope with version numbers containing
2736 strings of letters which the package management system cannot
2737 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2738 silly orderings (the author of this manual has heard of a
2739 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2740 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2741 <tt>2</tt> and so forth).
2745 <sect1 id="f-Description">
2746 <heading><tt>Description</tt></heading>
2749 In a source or binary control file, the <tt>Description</tt>
2750 field contains a description of the binary package, consisting
2751 of two parts, the synopsis or the short description, and the
2752 long description. The field's format is as follows:
2757 Description: <single line synopsis>
2758 <extended description over several lines>
2763 The lines in the extended description can have these formats:
2769 Those starting with a single space are part of a paragraph.
2770 Successive lines of this form will be word-wrapped when
2771 displayed. The leading space will usually be stripped off.
2775 Those starting with two or more spaces. These will be
2776 displayed verbatim. If the display cannot be panned
2777 horizontally, the displaying program will linewrap them "hard"
2778 (i.e., without taking account of word breaks). If it can they
2779 will be allowed to trail off to the right. None, one or two
2780 initial spaces may be deleted, but the number of spaces
2781 deleted from each line will be the same (so that you can have
2782 indenting work correctly, for example).
2786 Those containing a single space followed by a single full stop
2787 character. These are rendered as blank lines. This is the
2788 <em>only</em> way to get a blank line<footnote>
2789 Completely empty lines will not be rendered as blank lines.
2790 Instead, they will cause the parser to think you're starting
2791 a whole new record in the control file, and will therefore
2792 likely abort with an error.
2797 Those containing a space, a full stop and some more characters.
2798 These are for future expansion. Do not use them.
2804 Do not use tab characters. Their effect is not predictable.
2808 See <ref id="descriptions"> for further information on this.
2812 In a <file>.changes</file> file, the <tt>Description</tt> field
2813 contains a summary of the descriptions for the packages being
2818 The part of the field before the first newline is empty;
2819 thereafter each line has the name of a binary package and
2820 the summary description line from that binary package.
2821 Each line is indented by one space.
2826 <sect1 id="f-Distribution">
2827 <heading><tt>Distribution</tt></heading>
2830 In a <file>.changes</file> file or parsed changelog output
2831 this contains the (space-separated) name(s) of the
2832 distribution(s) where this version of the package should
2833 be installed. Valid distributions are determined by the
2834 archive maintainers.<footnote>
2835 Current distribution names are:
2836 <taglist compact="compact">
2837 <tag><em>stable</em></tag>
2839 This is the current "released" version of Debian
2840 GNU/Linux. Once the distribution is
2841 <em>stable</em> only security fixes and other
2842 major bug fixes are allowed. When changes are
2843 made to this distribution, the release number is
2844 increased (for example: 2.2r1 becomes 2.2r2 then
2848 <tag><em>unstable</em></tag>
2850 This distribution value refers to the
2851 <em>developmental</em> part of the Debian
2852 distribution tree. New packages, new upstream
2853 versions of packages and bug fixes go into the
2854 <em>unstable</em> directory tree. Download from
2855 this distribution at your own risk.
2858 <tag><em>testing</em></tag>
2860 This distribution value refers to the
2861 <em>testing</em> part of the Debian distribution
2862 tree. It receives its packages from the
2863 unstable distribution after a short time lag to
2864 ensure that there are no major issues with the
2865 unstable packages. It is less prone to breakage
2866 than unstable, but still risky. It is not
2867 possible to upload packages directly to
2871 <tag><em>frozen</em></tag>
2873 From time to time, the <em>testing</em>
2874 distribution enters a state of "code-freeze" in
2875 anticipation of release as a <em>stable</em>
2876 version. During this period of testing only
2877 fixes for existing or newly-discovered bugs will
2878 be allowed. The exact details of this stage are
2879 determined by the Release Manager.
2882 <tag><em>experimental</em></tag>
2884 The packages with this distribution value are
2885 deemed by their maintainers to be high
2886 risk. Oftentimes they represent early beta or
2887 developmental packages from various sources that
2888 the maintainers want people to try, but are not
2889 ready to be a part of the other parts of the
2890 Debian distribution tree. Download at your own
2896 You should list <em>all</em> distributions that the
2897 package should be installed into.
2901 More information is available in the Debian Developer's
2902 Reference, section "The Debian archive".
2909 <heading><tt>Date</tt></heading>
2912 This field includes the date the package was built or last edited.
2916 The value of this field is usually extracted from the
2917 <file>debian/changelog</file> file - see
2918 <ref id="dpkgchangelog">).
2922 <sect1 id="f-Format">
2923 <heading><tt>Format</tt></heading>
2926 This field specifies a format revision for the file.
2927 The most current format described in the Policy Manual
2928 is version <strong>1.5</strong>. The syntax of the
2929 format value is the same as that of a package version
2930 number except that no epoch or Debian revision is allowed
2931 - see <ref id="f-Version">.
2935 <sect1 id="f-Urgency">
2936 <heading><tt>Urgency</tt></heading>
2939 This is a description of how important it is to upgrade to
2940 this version from previous ones. It consists of a single
2941 keyword usually taking one of the values <tt>low</tt>,
2942 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2943 followed by an optional commentary (separated by a space)
2944 which is usually in parentheses. For example:
2947 Urgency: low (HIGH for users of diversions)
2953 The value of this field is usually extracted from the
2954 <file>debian/changelog</file> file - see
2955 <ref id="dpkgchangelog">.
2959 <sect1 id="f-Changes">
2960 <heading><tt>Changes</tt></heading>
2963 This field contains the human-readable changes data, describing
2964 the differences between the last version and the current one.
2968 There should be nothing in this field before the first
2969 newline; all the subsequent lines must be indented by at
2970 least one space; blank lines must be represented by a line
2971 consiting only of a space and a full stop.
2975 The value of this field is usually extracted from the
2976 <file>debian/changelog</file> file - see
2977 <ref id="dpkgchangelog">).
2981 Each version's change information should be preceded by a
2982 "title" line giving at least the version, distribution(s)
2983 and urgency, in a human-readable way.
2987 If data from several versions is being returned the entry
2988 for the most recent version should be returned first, and
2989 entries should be separated by the representation of a
2990 blank line (the "title" line may also be followed by the
2991 representation of blank line).
2995 <sect1 id="f-Binary">
2996 <heading><tt>Binary</tt></heading>
2999 This field is a list of binary packages.
3003 When it appears in the <file>.dsc</file> file it is the list
3004 of binary packages which a source package can produce. It
3005 does not necessarily produce all of these binary packages
3006 for every architecture. The source control file doesn't
3007 contain details of which architectures are appropriate for
3008 which of the binary packages.
3012 When it appears in a <file>.changes</file> file it lists the
3013 names of the binary packages actually being uploaded.
3017 The syntax is a list of binary packages separated by
3019 A space after each comma is conventional.
3020 </footnote>. Currently the packages must be separated using
3021 only spaces in the <file>.changes</file> file.
3025 <sect1 id="f-Installed-Size">
3026 <heading><tt>Installed-Size</tt></heading>
3029 This field appears in the control files of binary
3030 packages, and in the <file>Packages</file> files. It gives
3031 the total amount of disk space required to install the
3036 The disk space is represented in kilobytes as a simple
3041 <sect1 id="f-Files">
3042 <heading><tt>Files</tt></heading>
3045 This field contains a list of files with information about
3046 each one. The exact information and syntax varies with
3047 the context. In all cases the part of the field
3048 contents on the same line as the field name is empty. The
3049 remainder of the field is one line per file, each line
3050 being indented by one space and containing a number of
3051 sub-fields separated by spaces.
3055 In the <file>.dsc</file> file, each line contains the MD5
3056 checksum, size and filename of the tar file and (if applicable)
3057 diff file which make up the remainder of the source
3059 That is, the parts which are not the <tt>.dsc</tt>.
3061 The exact forms of the filenames are described
3062 in <ref id="pkg-sourcearchives">.
3066 In the <file>.changes</file> file this contains one line per
3067 file being uploaded. Each line contains the MD5 checksum,
3068 size, section and priority and the filename.
3069 The <qref id="f-Section">section</qref>
3070 and <qref id="f-Priority">priority</qref>
3071 are the values of the corresponding fields in
3072 the main source control file. If no section or priority is
3073 specified then <tt>-</tt> should be used, though section
3074 and priority values must be specified for new packages to
3075 be installed properly.
3079 The special value <tt>byhand</tt> for the section in a
3080 <tt>.changes</tt> file indicates that the file in question
3081 is not an ordinary package file and must by installed by
3082 hand by the distribution maintainers. If the section is
3083 <tt>byhand</tt> the priority should be <tt>-</tt>.
3087 If a new Debian revision of a package is being shipped and
3088 no new original source archive is being distributed the
3089 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3090 entry for the original source archive
3091 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3092 but the <file>.changes</file> file should leave it out. In
3093 this case the original source archive on the distribution
3094 site must match exactly, byte-for-byte, the original
3095 source archive which was used to generate the
3096 <file>.dsc</file> file and diff which are being uploaded.</p>
3099 <sect1 id="f-Closes">
3100 <heading><tt>Closes</tt></heading>
3103 A space-separated list of bug report numbers that the upload
3104 governed by the .changes file closes.
3111 <heading>User-defined fields</heading>
3114 Additional user-defined fields may be added to the
3115 source package control file. Such fields will be
3116 ignored, and not copied to (for example) binary or
3117 source package control files or upload control files.
3121 If you wish to add additional unsupported fields to
3122 these output files you should use the mechanism
3127 Fields in the main source control information file with
3128 names starting <tt>X</tt>, followed by one or more of
3129 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3130 be copied to the output files. Only the part of the
3131 field name after the hyphen will be used in the output
3132 file. Where the letter <tt>B</tt> is used the field
3133 will appear in binary package control files, where the
3134 letter <tt>S</tt> is used in source package control
3135 files and where <tt>C</tt> is used in upload control
3136 (<tt>.changes</tt>) files.
3140 For example, if the main source information control file
3143 XBS-Comment: I stand between the candle and the star.
3145 then the binary and source package control files will contain the
3148 Comment: I stand between the candle and the star.
3157 <chapt id="maintainerscripts">
3158 <heading>Package maintainer scripts and installation procedure</heading>
3161 <heading>Introduction to package maintainer scripts</heading>
3164 It is possible to supply scripts as part of a package which
3165 the package management system will run for you when your
3166 package is installed, upgraded or removed.
3170 These scripts are the files <prgn>preinst</prgn>,
3171 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3172 control area of the package. They must be proper executable
3173 files; if they are scripts (which is recommended), they must
3174 start with the usual <tt>#!</tt> convention. They should be
3175 readable and executable by anyone, and not world-writable.
3179 The package management system looks at the exit status from
3180 these scripts. It is important that they exit with a
3181 non-zero status if there is an error, so that the package
3182 management system can stop its processing. For shell
3183 scripts this means that you <em>almost always</em> need to
3184 use <tt>set -e</tt> (this is usually true when writing shell
3185 scripts, in fact). It is also important, of course, that
3186 they don't exit with a non-zero status if everything went
3191 When a package is upgraded a combination of the scripts from
3192 the old and new packages is called during the upgrade
3193 procedure. If your scripts are going to be at all
3194 complicated you need to be aware of this, and may need to
3195 check the arguments to your scripts.
3199 Broadly speaking the <prgn>preinst</prgn> is called before
3200 (a particular version of) a package is installed, and the
3201 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3202 before (a version of) a package is removed and the
3203 <prgn>postrm</prgn> afterwards.
3207 Programs called from maintainer scripts should not normally
3208 have a path prepended to them. Before installation is
3209 started, the package management system checks to see if the
3210 programs <prgn>ldconfig</prgn>,
3211 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3212 and <prgn>update-rc.d</prgn> can be found via the
3213 <tt>PATH</tt> environment variable. Those programs, and any
3214 other program that one would expect to be on the
3215 <tt>PATH</tt>, should thus be invoked without an absolute
3216 pathname. Maintainer scripts should also not reset the
3217 <tt>PATH</tt>, though they might choose to modify it by
3218 prepending or appending package-specific directories. These
3219 considerations really apply to all shell scripts.</p>
3222 <sect id="idempotency">
3223 <heading>Maintainer scripts Idempotency</heading>
3226 It is necessary for the error recovery procedures that the
3227 scripts be idempotent. This means that if it is run
3228 successfully, and then it is called again, it doesn't bomb
3229 out or cause any harm, but just ensures that everything is
3230 the way it ought to be. If the first call failed, or
3231 aborted half way through for some reason, the second call
3232 should merely do the things that were left undone the first
3233 time, if any, and exit with a success status if everything
3235 This is so that if an error occurs, the user interrupts
3236 <prgn>dpkg</prgn> or some other unforeseen circumstance
3237 happens you don't leave the user with a badly-broken
3238 package when <prgn>dpkg</prgn> attempts to repeat the
3244 <sect id="controllingterminal">
3245 <heading>Controlling terminal for maintainer scripts</heading>
3248 The maintainer scripts are guaranteed to run with a
3249 controlling terminal and can interact with the user.
3250 If they need to prompt for passwords, do full-screen
3251 interaction or something similar you should do these
3252 things to and from <file>/dev/tty</file>, since
3253 <prgn>dpkg</prgn> will at some point redirect scripts'
3254 standard input and output so that it can log the
3255 installation process. Likewise, because these scripts
3256 may be executed with standard output redirected into a
3257 pipe for logging purposes, Perl scripts should set
3258 unbuffered output by setting <tt>$|=1</tt> so that the
3259 output is printed immediately rather than being
3264 Each script should return a zero exit status for
3265 success, or a nonzero one for failure.
3269 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3274 <list compact="compact">
3276 <var>new-preinst</var> <tt>install</tt>
3279 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3282 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3285 <var>old-preinst</var> <tt>abort-upgrade</tt>
3286 <var>new-version</var>
3291 <list compact="compact">
3293 <var>postinst</var> <tt>configure</tt>
3294 <var>most-recently-configured-version</var>
3297 <var>old-postinst</var> <tt>abort-upgrade</tt>
3298 <var>new-version</var>
3301 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3302 <tt>in-favour</tt> <var>package</var>
3303 <var>new-version</var>
3306 <var>deconfigured's-postinst</var>
3307 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3308 <var>failed-install-package</var> <var>version</var>
3309 <tt>removing</tt> <var>conflicting-package</var>
3315 <list compact="compact">
3317 <var>prerm</var> <tt>remove</tt>
3320 <var>old-prerm</var> <tt>upgrade</tt>
3321 <var>new-version</var>
3324 <var>new-prerm</var> <tt>failed-upgrade</tt>
3325 <var>old-version</var>
3328 <var>conflictor's-prerm</var> <tt>remove</tt>
3329 <tt>in-favour</tt> <var>package</var>
3330 <var>new-version</var>
3333 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3334 <tt>in-favour</tt> <var>package-being-installed</var>
3335 <var>version</var> <tt>removing</tt>
3336 <var>conflicting-package</var>
3342 <list compact="compact">
3344 <var>postrm</var> <tt>remove</tt>
3347 <var>postrm</var> <tt>purge</tt>
3350 <var>old-postrm</var> <tt>upgrade</tt>
3351 <var>new-version</var>
3354 <var>new-postrm</var> <tt>failed-upgrade</tt>
3355 <var>old-version</var>
3358 <var>new-postrm</var> <tt>abort-install</tt>
3361 <var>new-postrm</var> <tt>abort-install</tt>
3362 <var>old-version</var>
3365 <var>new-postrm</var> <tt>abort-upgrade</tt>
3366 <var>old-version</var>
3369 <var>disappearer's-postrm</var> <tt>disappear</tt>
3370 <var>overwriter</var>
3371 <var>overwriter-version</var>
3377 <sect id="unpackphase">
3378 <heading>Details of unpack phase of installation or upgrade</heading>
3381 The procedure on installation/upgrade/overwrite/disappear
3382 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3383 stage of <tt>dpkg --install</tt>) is as follows. In each
3384 case, if a major error occurs (unless listed below) the
3385 actions are, in general, run backwards - this means that the
3386 maintainer scripts are run with different arguments in
3387 reverse order. These are the "error unwind" calls listed
3394 If a version of the package is already installed, call
3395 <example compact="compact">
3396 <var>old-prerm</var> upgrade <var>new-version</var>
3400 If the script runs but exits with a non-zero
3401 exit status, <prgn>dpkg</prgn> will attempt:
3402 <example compact="compact">
3403 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3405 Error unwind, for both the above cases:
3406 <example compact="compact">
3407 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3414 If a "conflicting" package is being removed at the same time:
3417 If any packages depended on that conflicting
3418 package and <tt>--auto-deconfigure</tt> is
3419 specified, call, for each such package:
3420 <example compact="compact">
3421 <var>deconfigured's-prerm</var> deconfigure \
3422 in-favour <var>package-being-installed</var> <var>version</var> \
3423 removing <var>conflicting-package</var> <var>version</var>
3426 <example compact="compact">
3427 <var>deconfigured's-postinst</var> abort-deconfigure \
3428 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3429 removing <var>conflicting-package</var> <var>version</var>
3431 The deconfigured packages are marked as
3432 requiring configuration, so that if
3433 <tt>--install</tt> is used they will be
3434 configured again if possible.
3437 To prepare for removal of the conflicting package, call:
3438 <example compact="compact">
3439 <var>conflictor's-prerm</var> remove \
3440 in-favour <var>package</var> <var>new-version</var>
3443 <example compact="compact">
3444 <var>conflictor's-postinst</var> abort-remove \
3445 in-favour <var>package</var> <var>new-version</var>
3454 If the package is being upgraded, call:
3455 <example compact="compact">
3456 <var>new-preinst</var> upgrade <var>old-version</var>
3460 Otherwise, if the package had some configuration
3461 files from a previous version installed (i.e., it
3462 is in the "configuration files only" state):
3463 <example compact="compact">
3464 <var>new-preinst</var> install <var>old-version</var>
3468 Otherwise (i.e., the package was completely purged):
3469 <example compact="compact">
3470 <var>new-preinst</var> install
3472 Error unwind actions, respectively:
3473 <example compact="compact">
3474 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3475 <var>new-postrm</var> abort-install <var>old-version</var>
3476 <var>new-postrm</var> abort-install
3484 The new package's files are unpacked, overwriting any
3485 that may be on the system already, for example any
3486 from the old version of the same package or from
3487 another package. Backups of the old files are kept
3488 temporarily, and if anything goes wrong the package
3489 management system will attempt to put them back as
3490 part of the error unwind.
3494 It is an error for a package to contain files which
3495 are on the system in another package, unless
3496 <tt>Replaces</tt> is used (see <ref id="replaces">).
3498 The following paragraph is not currently the case:
3499 Currently the <tt>- - force-overwrite</tt> flag is
3500 enabled, downgrading it to a warning, but this may not
3506 It is a more serious error for a package to contain a
3507 plain file or other kind of non-directory where another
3508 package has a directory (again, unless
3509 <tt>Replaces</tt> is used). This error can be
3510 overridden if desired using
3511 <tt>--force-overwrite-dir</tt>, but this is not
3516 Packages which overwrite each other's files produce
3517 behavior which, though deterministic, is hard for the
3518 system administrator to understand. It can easily
3519 lead to "missing" programs if, for example, a package
3520 is installed which overwrites a file from another
3521 package, and is then removed again.<footnote>
3522 Part of the problem is due to what is arguably a
3523 bug in <prgn>dpkg</prgn>.
3528 A directory will never be replaced by a symbolic link
3529 to a directory or vice versa; instead, the existing
3530 state (symlink or not) will be left alone and
3531 <prgn>dpkg</prgn> will follow the symlink if there is
3540 If the package is being upgraded, call
3541 <example compact="compact">
3542 <var>old-postrm</var> upgrade <var>new-version</var>
3546 If this fails, <prgn>dpkg</prgn> will attempt:
3547 <example compact="compact">
3548 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3550 Error unwind, for both cases:
3551 <example compact="compact">
3552 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3559 This is the point of no return - if
3560 <prgn>dpkg</prgn> gets this far, it won't back off
3561 past this point if an error occurs. This will
3562 leave the package in a fairly bad state, which
3563 will require a successful re-installation to clear
3564 up, but it's when <prgn>dpkg</prgn> starts doing
3565 things that are irreversible.
3570 Any files which were in the old version of the package
3571 but not in the new are removed.
3575 The new file list replaces the old.
3579 The new maintainer scripts replace the old.
3583 Any packages all of whose files have been overwritten
3584 during the installation, and which aren't required for
3585 dependencies, are considered to have been removed.
3586 For each such package
3589 <prgn>dpkg</prgn> calls:
3590 <example compact="compact">
3591 <var>disappearer's-postrm</var> disappear \
3592 <var>overwriter</var> <var>overwriter-version</var>
3596 The package's maintainer scripts are removed.
3599 It is noted in the status database as being in a
3600 sane state, namely not installed (any conffiles
3601 it may have are ignored, rather than being
3602 removed by <prgn>dpkg</prgn>). Note that
3603 disappearing packages do not have their prerm
3604 called, because <prgn>dpkg</prgn> doesn't know
3605 in advance that the package is going to
3612 Any files in the package we're unpacking that are also
3613 listed in the file lists of other packages are removed
3614 from those lists. (This will lobotomize the file list
3615 of the "conflicting" package if there is one.)
3619 The backup files made during installation, above, are
3625 The new package's status is now sane, and recorded as
3630 Here is another point of no return - if the
3631 conflicting package's removal fails we do not unwind
3632 the rest of the installation; the conflicting package
3633 is left in a half-removed limbo.
3638 If there was a conflicting package we go and do the
3639 removal actions (described below), starting with the
3640 removal of the conflicting package's files (any that
3641 are also in the package being installed have already
3642 been removed from the conflicting package's file list,
3643 and so do not get removed now).
3649 <sect id="configdetails"><heading>Details of configuration</heading>
3652 When we configure a package (this happens with <tt>dpkg
3653 --install</tt> and <tt>dpkg --configure</tt>), we first
3654 update any <tt>conffile</tt>s and then call:
3655 <example compact="compact">
3656 <var>postinst</var> configure <var>most-recently-configured-version</var>
3661 No attempt is made to unwind after errors during
3666 If there is no most recently configured version
3667 <prgn>dpkg</prgn> will pass a null argument.
3670 Historical note: Truly ancient (pre-1997) versions of
3671 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3672 (including the angle brackets) in this case. Even older
3673 ones did not pass a second argument at all, under any
3674 circumstance. Note that upgrades using such an old dpkg
3675 version are unlikely to work for other reasons, even if
3676 this old argument behavior is handled by your postinst script.
3682 <sect id="removedetails"><heading>Details of removal and/or
3683 configuration purging</heading>
3688 <example compact="compact">
3689 <var>prerm</var> remove
3693 The package's files are removed (except <tt>conffile</tt>s).
3696 <example compact="compact">
3697 <var>postrm</var> remove
3702 All the maintainer scripts except the <prgn>postrm</prgn>
3707 If we aren't purging the package we stop here. Note
3708 that packages which have no <prgn>postrm</prgn> and no
3709 <tt>conffile</tt>s are automatically purged when
3710 removed, as there is no difference except for the
3711 <prgn>dpkg</prgn> status.
3715 The <tt>conffile</tt>s and any backup files
3716 (<tt>~</tt>-files, <tt>#*#</tt> files,
3717 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3721 <example compact="compact">
3722 <var>postrm</var> purge
3726 The package's file list is removed.
3730 If there are problems during this process, we call
3731 <example compact="compact">postinst
3732 abort-remove</example>. No other attempt is made to unwind
3733 after errors during removal.
3739 <chapt id="relationships">
3740 <heading>Declaring relationships between packages</heading>
3742 <sect id="depsyntax">
3743 <heading>Syntax of relationship fields</heading>
3746 These fields all have a uniform syntax. They are a list of
3747 package names separated by commas.
3751 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3752 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3753 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3754 control file fields of the package, which declare
3755 dependencies on other packages, the package names listed may
3756 also include lists of alternative package names, separated
3757 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3758 if any one of the alternative packages is installed, that
3759 part of the dependency is considered to be satisfied.
3763 All of the fields except for <tt>Provides</tt> may restrict
3764 their applicability to particular versions of each named
3765 package. This is done in parentheses after each individual
3766 package name; the parentheses should contain a relation from
3767 the list below followed by a version number, in the format
3768 described in <ref id="f-Version">.
3772 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3773 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3774 strictly earlier, earlier or equal, exactly equal, later or
3775 equal and strictly later, respectively. The deprecated
3776 forms <tt><</tt> and <tt>></tt> were used to mean
3777 earlier/later or equal, rather than strictly earlier/later,
3778 so they should not appear in new packages (though
3779 <prgn>dpkg</prgn> still supports them).
3783 Whitespace may appear at any point in the version
3784 specification subject to the rules in <ref
3785 id="controlsyntax">, and must appear where it's necessary to
3786 disambiguate; it is not otherwise significant. For
3787 consistency and in case of future changes to
3788 <prgn>dpkg</prgn> it is recommended that a single space be
3789 used after a version relationship and before a version
3790 number; it is also conventional to put a single space after
3791 each comma, on either side of each vertical bar, and before
3792 each open parenthesis.
3796 For example, a list of dependencies might appear as:
3797 <example compact="compact">
3800 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3805 All fields that specify build-time relationships
3806 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3807 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3808 may be restricted to a certain set of architectures. This
3809 is indicated in brackets after each individual package name and
3810 the optional version specification. The brackets enclose a
3811 list of Debian architecture names separated by whitespace.
3812 Exclamation marks may be prepended to each of the names.
3813 (It is not permitted for some names to be prepended with
3814 exclamation marks and others not.) If the current Debian
3815 host architecture is not in this list and there are no
3816 exclamation marks in the list, or it is in the list with a
3817 prepended exclamation mark, the package name and the
3818 associated version specification are ignored completely for
3819 the purposes of defining the relationships.
3824 <example compact="compact">
3826 Build-Depends-Indep: texinfo
3827 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3828 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3833 Note that the binary package relationship fields such as
3834 <tt>Depends</tt> appear in one of the binary package
3835 sections of the control file, whereas the build-time
3836 relationships such as <tt>Build-Depends</tt> appear in the
3837 source package section of the control file (which is the
3842 <sect id="binarydeps">
3843 <heading>Binary Dependencies - <tt>Depends</tt>,
3844 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3845 <tt>Pre-Depends</tt>
3849 Packages can declare in their control file that they have
3850 certain relationships to other packages - for example, that
3851 they may not be installed at the same time as certain other
3852 packages, and/or that they depend on the presence of others.
3856 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3857 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3858 <tt>Conflicts</tt> control file fields.
3862 These six fields are used to declare a dependency
3863 relationship by one package on another. Except for
3864 <tt>Enhances</tt>, they appear in the depending (binary)
3865 package's control file. (<tt>Enhances</tt> appears in the
3866 recommending package's control file.)
3870 A <tt>Depends</tt> field takes effect <em>only</em> when a
3871 package is to be configured. It does not prevent a package
3872 being on the system in an unconfigured state while its
3873 dependencies are unsatisfied, and it is possible to replace
3874 a package whose dependencies are satisfied and which is
3875 properly installed with a different version whose
3876 dependencies are not and cannot be satisfied; when this is
3877 done the depending package will be left unconfigured (since
3878 attempts to configure it will give errors) and will not
3879 function properly. If it is necessary, a
3880 <tt>Pre-Depends</tt> field can be used, which has a partial
3881 effect even when a package is being unpacked, as explained
3882 in detail below. (The other three dependency fields,
3883 <tt>Recommends</tt>, <tt>Suggests</tt> and
3884 <tt>Enhances</tt>, are only used by the various front-ends
3885 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3889 For this reason packages in an installation run are usually
3890 all unpacked first and all configured later; this gives
3891 later versions of packages with dependencies on later
3892 versions of other packages the opportunity to have their
3893 dependencies satisfied.
3897 The <tt>Depends</tt> field thus allows package maintainers
3898 to impose an order in which packages should be configured.
3902 The meaning of the five dependency fields is as follows:
3904 <tag><tt>Depends</tt></tag>
3907 This declares an absolute dependency. A package will
3908 not be configured unless all of the packages listed in
3909 its <tt>Depends</tt> field have been correctly
3914 The <tt>Depends</tt> field should be used if the
3915 depended-on package is required for the depending
3916 package to provide a significant amount of
3921 The <tt>Depends</tt> field should also be used if the
3922 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3923 <prgn>postrm</prgn> scripts require the package to be
3924 present in order to run. Note, however, that the
3925 <prgn>postrm</prgn> cannot rely on any non-essential
3926 packages to be present during the <tt>purge</tt>
3930 <tag><tt>Recommends</tt></tag>
3933 This declares a strong, but not absolute, dependency.
3937 The <tt>Recommends</tt> field should list packages
3938 that would be found together with this one in all but
3939 unusual installations.
3943 <tag><tt>Suggests</tt></tag>
3945 This is used to declare that one package may be more
3946 useful with one or more others. Using this field
3947 tells the packaging system and the user that the
3948 listed packages are related to this one and can
3949 perhaps enhance its usefulness, but that installing
3950 this one without them is perfectly reasonable.
3953 <tag><tt>Enhances</tt></tag>
3955 This field is similar to Suggests but works in the
3956 opposite direction. It is used to declare that a
3957 package can enhance the functionality of another
3961 <tag><tt>Pre-Depends</tt></tag>
3964 This field is like <tt>Depends</tt>, except that it
3965 also forces <prgn>dpkg</prgn> to complete installation
3966 of the packages named before even starting the
3967 installation of the package which declares the
3968 pre-dependency, as follows:
3972 When a package declaring a pre-dependency is about to
3973 be <em>unpacked</em> the pre-dependency can be
3974 satisfied if the depended-on package is either fully
3975 configured, <em>or even if</em> the depended-on
3976 package(s) are only unpacked or half-configured,
3977 provided that they have been configured correctly at
3978 some point in the past (and not removed or partially
3979 removed since). In this case, both the
3980 previously-configured and currently unpacked or
3981 half-configured versions must satisfy any version
3982 clause in the <tt>Pre-Depends</tt> field.
3986 When the package declaring a pre-dependency is about
3987 to be <em>configured</em>, the pre-dependency will be
3988 treated as a normal <tt>Depends</tt>, that is, it will
3989 be considered satisfied only if the depended-on
3990 package has been correctly configured.
3994 <tt>Pre-Depends</tt> should be used sparingly,
3995 preferably only by packages whose premature upgrade or
3996 installation would hamper the ability of the system to
3997 continue with any upgrade that might be in progress.
4001 <tt>Pre-Depends</tt> are also required if the
4002 <prgn>preinst</prgn> script depends on the named
4003 package. It is best to avoid this situation if
4011 When selecting which level of dependency to use you should
4012 consider how important the depended-on package is to the
4013 functionality of the one declaring the dependency. Some
4014 packages are composed of components of varying degrees of
4015 importance. Such a package should list using
4016 <tt>Depends</tt> the package(s) which are required by the
4017 more important components. The other components'
4018 requirements may be mentioned as Suggestions or
4019 Recommendations, as appropriate to the components' relative
4024 <sect id="conflicts">
4025 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4028 When one binary package declares a conflict with another
4029 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4030 refuse to allow them to be installed on the system at the
4035 If one package is to be installed, the other must be removed
4036 first - if the package being installed is marked as
4037 replacing (see <ref id="replaces">) the one on the system,
4038 or the one on the system is marked as deselected, or both
4039 packages are marked <tt>Essential</tt>, then
4040 <prgn>dpkg</prgn> will automatically remove the package
4041 which is causing the conflict, otherwise it will halt the
4042 installation of the new package with an error. This
4043 mechanism is specifically designed to produce an error when
4044 the installed package is <tt>Essential</tt>, but the new
4049 A package will not cause a conflict merely because its
4050 configuration files are still installed; it must be at least
4055 A special exception is made for packages which declare a
4056 conflict with their own package name, or with a virtual
4057 package which they provide (see below): this does not
4058 prevent their installation, and allows a package to conflict
4059 with others providing a replacement for it. You use this
4060 feature when you want the package in question to be the only
4061 package providing some feature.
4065 A <tt>Conflicts</tt> entry should almost never have an
4066 "earlier than" version clause. This would prevent
4067 <prgn>dpkg</prgn> from upgrading or installing the package
4068 which declared such a conflict until the upgrade or removal
4069 of the conflicted-with package had been completed.
4073 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4077 As well as the names of actual ("concrete") packages, the
4078 package relationship fields <tt>Depends</tt>,
4079 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4080 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4081 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4082 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4083 may mention "virtual packages".
4087 A <em>virtual package</em> is one which appears in the
4088 <tt>Provides</tt> control file field of another package.
4089 The effect is as if the package(s) which provide a
4090 particular virtual package name had been listed by name
4091 everywhere the virtual package name appears. (See also <ref
4096 If there are both concrete and virtual packages of the same
4097 name, then the dependency may be satisfied (or the conflict
4098 caused) by either the concrete package with the name in
4099 question or any other concrete package which provides the
4100 virtual package with the name in question. This is so that,
4101 for example, supposing we have
4102 <example compact="compact">
4106 and someone else releases an enhanced version of the
4107 <tt>bar</tt> package (for example, a non-US variant), they
4109 <example compact="compact">
4113 and the <tt>bar-plus</tt> package will now also satisfy the
4114 dependency for the <tt>foo</tt> package.
4118 If a dependency or a conflict has a version number attached
4119 then only real packages will be considered to see whether
4120 the relationship is satisfied (or the prohibition violated,
4121 for a conflict) - it is assumed that a real package which
4122 provides the virtual package is not of the "right" version.
4123 So, a <tt>Provides</tt> field may not contain version
4124 numbers, and the version number of the concrete package
4125 which provides a particular virtual package will not be
4126 looked at when considering a dependency on or conflict with
4127 the virtual package name.
4131 It is likely that the ability will be added in a future
4132 release of <prgn>dpkg</prgn> to specify a version number for
4133 each virtual package it provides. This feature is not yet
4134 present, however, and is expected to be used only
4139 If you want to specify which of a set of real packages
4140 should be the default to satisfy a particular dependency on
4141 a virtual package, you should list the real package as an
4142 alternative before the virtual one.
4147 <sect id="replaces"><heading>Overwriting files and replacing
4148 packages - <tt>Replaces</tt></heading>
4151 Packages can declare in their control file that they should
4152 overwrite files in certain other packages, or completely
4153 replace other packages. The <tt>Replaces</tt> control file
4154 field has these two distinct purposes.
4157 <sect1><heading>Overwriting files in other packages</heading>
4160 Firstly, as mentioned before, it is usually an error for a
4161 package to contain files which are on the system in
4166 However, if the overwriting package declares that it
4167 <tt>Replaces</tt> the one containing the file being
4168 overwritten, then <prgn>dpkg</prgn> will replace the file
4169 from the old package with that from the new. The file
4170 will no longer be listed as "owned" by the old package.
4174 If a package is completely replaced in this way, so that
4175 <prgn>dpkg</prgn> does not know of any files it still
4176 contains, it is considered to have "disappeared". It will
4177 be marked as not wanted on the system (selected for
4178 removal) and not installed. Any <tt>conffile</tt>s
4179 details noted for the package will be ignored, as they
4180 will have been taken over by the overwriting package. The
4181 package's <prgn>postrm</prgn> script will be run with a
4182 special argument to allow the package to do any final
4183 cleanup required. See <ref id="mscriptsinstact">.
4186 Replaces is a one way relationship -- you have to
4187 install the replacing package after the replaced
4194 For this usage of <tt>Replaces</tt>, virtual packages (see
4195 <ref id="virtual">) are not considered when looking at a
4196 <tt>Replaces</tt> field - the packages declared as being
4197 replaced must be mentioned by their real names.
4201 Furthermore, this usage of <tt>Replaces</tt> only takes
4202 effect when both packages are at least partially on the
4203 system at once, so that it can only happen if they do not
4204 conflict or if the conflict has been overridden.
4209 <sect1><heading>Replacing whole packages, forcing their
4213 Secondly, <tt>Replaces</tt> allows the packaging system to
4214 resolve which package should be removed when there is a
4215 conflict - see <ref id="conflicts">. This usage only
4216 takes effect when the two packages <em>do</em> conflict,
4217 so that the two usages of this field do not interfere with
4222 In this situation, the package declared as being replaced
4223 can be a virtual package, so for example, all mail
4224 transport agents (MTAs) would have the following fields in
4225 their control files:
4226 <example compact="compact">
4227 Provides: mail-transport-agent
4228 Conflicts: mail-transport-agent
4229 Replaces: mail-transport-agent
4231 ensuring that only one MTA can be installed at any one
4236 <sect id="sourcebinarydeps">
4237 <heading>Relationships between source and binary packages -
4238 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4239 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4243 Source packages that require certain binary packages to be
4244 installed or absent at the time of building the package
4245 can declare relationships to those binary packages.
4249 This is done using the <tt>Build-Depends</tt>,
4250 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4251 <tt>Build-Conflicts-Indep</tt> control file fields.
4255 Build-dependencies on "build-essential" binary packages can be
4256 omitted. Please see <ref id="pkg-relations"> for more information.
4260 The dependencies and conflicts they define must be satisfied
4261 (as defined earlier for binary packages) in order to invoke
4262 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4264 If you make "build-arch" or "binary-arch", you need
4265 Build-Depends. If you make "build-indep" or
4266 "binary-indep", you need Build-Depends and
4267 Build-Depends-Indep. If you make "build" or "binary",
4271 There is no Build-Depends-Arch; the autobuilders will
4272 only need the Build-Depends if they know how to build
4273 only build-arch and binary-arch. Anyone building the
4274 build-indep/binary-indep targets is basically assumed to
4275 be building the whole package and so installs all build
4279 The purpose of the original split, I recall, was so that
4280 the autobuilders wouldn't need to install extra packages
4281 needed only for the binary-indep targets. But without a
4282 build-arch/build-indep split, this didn't work, since
4283 most of the work is done in the build target, not in the
4289 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4291 The <tt>Build-Depends</tt> and
4292 <tt>Build-Conflicts</tt> fields must be satisfied when
4293 any of the following targets is invoked:
4294 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4295 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4296 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4298 <tag><tt>Build-Depends-Indep</tt>,
4299 <tt>Build-Conflicts-Indep</tt></tag>
4301 The <tt>Build-Depends-Indep</tt> and
4302 <tt>Build-Conflicts-Indep</tt> fields must be
4303 satisfied when any of the following targets is
4304 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4305 <tt>binary</tt> and <tt>binary-indep</tt>.
4315 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4318 Packages containing shared libraries must be constructed with
4319 a little care to make sure that the shared library is always
4320 available. This is especially important for packages whose
4321 shared libraries are vitally important, such as the C library
4322 (currently <tt>libc6</tt>).
4326 Packages involving shared libraries should be split up into
4327 several binary packages. This section mostly deals with how
4328 this separation is to be accomplished; rules for files within
4329 the shared library packages are in <ref id="libraries"> instead.
4332 <sect id="sharedlibs-runtime">
4333 <heading>Run-time shared libraries</heading>
4336 The run-time shared library needs to be placed in a package called
4337 <package><var>libraryname</var><var>soversion</var></package>, where
4338 <file><var>soversion</var></file> is the version number in the
4339 soname of the shared library<footnote>
4340 The soname is the shared object name: it's the thing
4341 that has to match exactly between building an executable
4342 and running it for the dynamic linker to be able run the
4343 program. For example, if the soname of the library is
4344 <file>libfoo.so.6</file>, the library package would be
4345 called <file>libfoo6</file>.
4347 Alternatively, if it would be confusing to directly append
4348 <var>soversion</var> to <var>libraryname</var> (e.g. because
4349 <var>libraryname</var> itself ends in a number), you may use
4350 <package><var>libraryname</var>-<var>soversion</var></package> and
4351 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4356 If you have several shared libraries built from the same
4357 source tree you may lump them all together into a single
4358 shared library package, provided that you change all of
4359 their sonames at once (so that you don't get filename
4360 clashes if you try to install different versions of the
4361 combined shared libraries package).
4365 The package should install the shared libraries under
4366 their normal names. For example, the <package>libgdbm3</package>
4367 package should install <file>libgdbm.so.3.0.0</file> as
4368 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4369 renamed or re-linked by any <prgn>prerm</prgn> or
4370 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4371 of renaming things safely without affecting running programs,
4372 and attempts to interfere with this are likely to lead to
4377 Shared libraries should not be installed executable, since
4378 the dynamic linker does not require this and trying to
4379 execute a shared library usually results in a core dump.
4383 The run-time library package should include the symbolic link that
4384 <prgn>ldconfig</prgn> would create for the shared libraries.
4385 For example, the <package>libgdbm3</package> package should include
4386 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4387 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4388 linker (for example <prgn>ld.so</prgn> or
4389 <prgn>ld-linux.so.*</prgn>) can find the library between the
4390 time that <prgn>dpkg</prgn> installs it and the time that
4391 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4393 The package management system requires the library to be
4394 placed before the symbolic link pointing to it in the
4395 <file>.deb</file> file. This is so that when
4396 <prgn>dpkg</prgn> comes to install the symlink
4397 (overwriting the previous symlink pointing at an older
4398 version of the library), the new shared library is already
4399 in place. In the past, this was achieved by creating the
4400 library in the temporary packaging directory before
4401 creating the symlink. Unfortunately, this was not always
4402 effective, since the building of the tar file in the
4403 <file>.deb</file> depended on the behavior of the underlying
4404 file system. Some file systems (such as reiserfs) reorder
4405 the files so that the order of creation is forgotten.
4406 Since version 1.7.0, <prgn>dpkg</prgn>
4407 reorders the files itself as necessary when building a
4408 package. Thus it is no longer important to concern
4409 oneself with the order of file creation.
4413 <sect1 id="ldconfig">
4414 <heading><tt>ldconfig</tt></heading>
4417 Any package installing shared libraries in one of the default
4418 library directories of the dynamic linker (which are currently
4419 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4420 listed in <file>/etc/ld.so.conf</file><footnote>
4422 <list compact="compact">
4423 <item>/usr/X11R6/lib/Xaw3d</item>
4424 <item>/usr/local/lib</item>
4425 <item>/usr/lib/libc5-compat</item>
4426 <item>/lib/libc5-compat</item>
4427 <item>/usr/X11R6/lib</item>
4430 must use <prgn>ldconfig</prgn> to update the shared library
4435 The package must call <prgn>ldconfig</prgn> in the
4436 <prgn>postinst</prgn> script if the first argument is
4437 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4438 optionally invoke <prgn>ldconfig</prgn> at other times. The
4439 package should call <prgn>ldconfig</prgn> in the
4440 <prgn>postrm</prgn> script if the first argument is
4441 <tt>remove</tt>. The maintainer scripts must not invoke
4442 <prgn>ldconfig</prgn> under any circumstances other than those
4443 described in this paragraph.<footnote>
4445 During install or upgrade, the preinst is called before
4446 the new files are installed, so calling "ldconfig" is
4447 pointless. The preinst of an existing package can also be
4448 called if an upgrade fails. However, this happens during
4449 the critical time when a shared libs may exist on-disk
4450 under a temporary name. Thus, it is dangerous and
4451 forbidden by current policy to call "ldconfig" at this
4456 When a package is installed or upgraded, "postinst
4457 configure" runs after the new files are safely on-disk.
4458 Since it is perfectly safe to invoke ldconfig
4459 unconditionally in a postinst, it is OK for a package to
4460 simply put ldconfig in its postinst without checking the
4461 argument. The postinst can also be called to recover from
4462 a failed upgrade. This happens before any new files are
4463 unpacked, so there is no reason to call "ldconfig" at this
4468 For a package that is being removed, prerm is
4469 called with all the files intact, so calling ldconfig is
4470 useless. The other calls to "prerm" happen in the case of
4471 upgrade at a time when all the files of the old package
4472 are on-disk, so again calling "ldconfig" is pointless.
4476 postrm, on the other hand, is called with the "remove"
4477 argument just after the files are removed, so this is the
4478 proper time to call "ldconfig" to notify the system of the
4479 fact shared libraries from the package are removed.
4480 The postrm can be called at several other times. At the
4481 time of "postrm purge", "postrm abort-install", or "postrm
4482 abort-upgrade", calling "ldconfig" is useless because the
4483 shared lib files are not on-disk. However, when "postrm"
4484 is invoked with arguments "upgrade", "failed-upgrade", or
4485 "disappear", a shared lib may exist on-disk under a
4494 <sect id="sharedlibs-runtime-progs">
4495 <heading>Run-time support programs</heading>
4498 If your package has some run-time support programs which use
4499 the shared library you must not put them in the shared
4500 library package. If you do that then you won't be able to
4501 install several versions of the shared library without
4502 getting filename clashes.
4506 Instead, either create another package for the runtime binaries
4507 (this package might typically be named
4508 <package><var>libraryname</var>-runtime</package>; note the absence
4509 of the <var>soversion</var> in the package name), or if the
4510 development package is small, include them in there.
4514 <sect id="sharedlibs-static">
4515 <heading>Static libraries</heading>
4518 The static library (<file><var>libraryname.a</var></file>)
4519 is usually provided in addition to the shared version.
4520 It is placed into the development package (see below).
4524 In some cases, it is acceptable for a library to be
4525 available in static form only; these cases include:
4527 <item>libraries for languages whose shared library support
4528 is immature or unstable</item>
4529 <item>libraries whose interfaces are in flux or under
4530 development (commonly the case when the library's
4531 major version number is zero, or where the ABI breaks
4532 across patchlevels)</item>
4533 <item>libraries which are explicitly intended to be
4534 available only in static form by their upstream
4539 <sect id="sharedlibs-dev">
4540 <heading>Development files</heading>
4543 The development files associated to a shared library need to be
4544 placed in a package called
4545 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4546 or if you prefer only to support one development version at a
4547 time, <package><var>libraryname</var>-dev</package>.
4551 In case several development versions of a library exist, you may
4552 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4553 <ref id="conflicts">) to ensure that the user only installs one
4554 development version at a time (as different development versions are
4555 likely to have the same header files in them, which would cause a
4556 filename clash if both were installed).
4560 The development package should contain a symlink for the associated
4561 shared library without a version number. For example, the
4562 <package>libgdbm-dev</package> package should include a symlink
4563 from <file>/usr/lib/libgdbm.so</file> to
4564 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4565 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4566 <file>libgdbm.so</file> when compiling dynamically.
4570 <sect id="sharedlibs-intradeps">
4571 <heading>Dependencies between the packages of the same library</heading>
4574 Typically the development version should have an exact
4575 version dependency on the runtime library, to make sure that
4576 compilation and linking happens correctly. The
4577 <tt>${Source-Version}</tt> substitution variable can be
4578 useful for this purpose.
4582 <sect id="sharedlibs-shlibdeps">
4583 <heading>Dependencies between the library and other packages -
4584 the <tt>shlibs</tt> system</heading>
4587 If a package contains a binary or library which links to a
4588 shared library, we must ensure that when the package is
4589 installed on the system, all of the libraries needed are
4590 also installed. This requirement led to the creation of the
4591 <tt>shlibs</tt> system, which is very simple in its design:
4592 any package which <em>provides</em> a shared library also
4593 provides information on the package dependencies required to
4594 ensure the presence of this library, and any package which
4595 <em>uses</em> a shared library uses this information to
4596 determine the dependencies it requires. The files which
4597 contain the mapping from shared libraries to the necessary
4598 dependency information are called <file>shlibs</file> files.
4602 Thus, when a package is built which contains any shared
4603 libraries, it must provide a <file>shlibs</file> file for other
4604 packages to use, and when a package is built which contains
4605 any shared libraries or compiled binaries, it must run
4606 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4607 on these to determine the libraries used and hence the
4608 dependencies needed by this package.<footnote>
4610 In the past, the shared libraries linked to were
4611 determined by calling <prgn>ldd</prgn>, but now
4612 <prgn>objdump</prgn> is used to do this. The only
4613 change this makes to package building is that
4614 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4615 libraries, whereas in the past this was unnecessary.
4616 The rest of this footnote explains the advantage that
4621 We say that a binary <tt>foo</tt> <em>directly</em> uses
4622 a library <tt>libbar</tt> if it is explicitly linked
4623 with that library (that is, it uses the flag
4624 <tt>-lbar</tt> during the linking stage). Other
4625 libraries that are needed by <tt>libbar</tt> are linked
4626 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4627 linker will load them automatically when it loads
4628 <tt>libbar</tt>. A package should depend on
4629 the libraries it directly uses, and the dependencies for
4630 those libraries should automatically pull in the other
4635 Unfortunately, the <prgn>ldd</prgn> program shows both
4636 the directly and indirectly used libraries, meaning that
4637 the dependencies determined included both direct and
4638 indirect dependencies. The use of <prgn>objdump</prgn>
4639 avoids this problem by determining only the directly
4644 A good example of where this helps is the following. We
4645 could update <tt>libimlib</tt> with a new version that
4646 supports a new graphics format called dgf (but retaining
4647 the same major version number). If we used the old
4648 <prgn>ldd</prgn> method, every package that uses
4649 <tt>libimlib</tt> would need to be recompiled so it
4650 would also depend on <tt>libdgf</tt> or it wouldn't run
4651 due to missing symbols. However with the new system,
4652 packages using <tt>libimlib</tt> can rely on
4653 <tt>libimlib</tt> itself having the dependency on
4654 <tt>libdgf</tt> and so they would not need rebuilding.
4660 In the following sections, we will first describe where the
4661 various <tt>shlibs</tt> files are to be found, then how to
4662 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4663 file format and how to create them if your package contains a
4668 <heading>The <tt>shlibs</tt> files present on the system</heading>
4671 There are several places where <tt>shlibs</tt> files are
4672 found. The following list gives them in the order in which
4674 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4675 (The first one which gives the required information is used.)
4681 <p><file>debian/shlibs.local</file></p>
4684 This lists overrides for this package. Its use is
4685 described below (see <ref id="shlibslocal">).
4690 <p><file>/etc/dpkg/shlibs.override</file></p>
4693 This lists global overrides. This list is normally
4694 empty. It is maintained by the local system
4700 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4703 When packages are being built, any
4704 <file>debian/shlibs</file> files are copied into the
4705 control file area of the temporary build directory and
4706 given the name <file>shlibs</file>. These files give
4707 details of any shared libraries included in the
4709 An example may help here. Let us say that the
4710 source package <tt>foo</tt> generates two binary
4711 packages, <tt>libfoo2</tt> and
4712 <tt>foo-runtime</tt>. When building the binary
4713 packages, the two packages are created in the
4714 directories <file>debian/libfoo2</file> and
4715 <file>debian/foo-runtime</file> respectively.
4716 (<file>debian/tmp</file> could be used instead of one
4717 of these.) Since <tt>libfoo2</tt> provides the
4718 <tt>libfoo</tt> shared library, it will require a
4719 <tt>shlibs</tt> file, which will be installed in
4720 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4722 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4723 when <prgn>dpkg-shlibdeps</prgn> is run on the
4725 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4727 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4728 determine whether <tt>foo-prog</tt>'s library
4729 dependencies are satisfied by any of the libraries
4730 provided by <tt>libfoo2</tt>. For this reason,
4731 <prgn>dpkg-shlibdeps</prgn> must only be run once
4732 all of the individual binary packages'
4733 <tt>shlibs</tt> files have been installed into the
4740 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4743 These are the <file>shlibs</file> files corresponding to
4744 all of the packages installed on the system, and are
4745 maintained by the relevant package maintainers.
4750 <p><file>/etc/dpkg/shlibs.default</file></p>
4753 This file lists any shared libraries whose packages
4754 have failed to provide correct <file>shlibs</file> files.
4755 It was used when the <file>shlibs</file> setup was first
4756 introduced, but it is now normally empty. It is
4757 maintained by the <tt>dpkg</tt> maintainer.
4765 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4766 <file>shlibs</file> files</heading>
4770 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4771 into your <file>debian/rules</file> file. If your package
4772 contains only compiled binaries and libraries (but no scripts),
4773 you can use a command such as:
4774 <example compact="compact">
4775 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4776 debian/tmp/usr/lib/*
4778 Otherwise, you will need to explicitly list the compiled
4779 binaries and libraries.<footnote>
4780 If you are using <tt>debhelper</tt>, the
4781 <prgn>dh_shlibdeps</prgn> program will do this work for
4782 you. It will also correctly handle multi-binary
4788 This command puts the dependency information into the
4789 <file>debian/substvars</file> file, which is then used by
4790 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4791 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4792 field in the control file for this to work.
4796 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4797 done. If it does complain you might need to create your own
4798 <file>debian/shlibs.local</file> file, as explained below (see
4799 <ref id="shlibslocal">).
4803 If you have multiple binary packages, you will need to call
4804 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4805 compiled libraries or binaries. In such a case, you will
4806 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4807 utilities to specify a different <file>substvars</file> file.
4811 For more details on dpkg-shlibdeps, please see
4812 <ref id="pkg-dpkg-shlibdeps"> and
4813 <manref name="dpkg-shlibdeps" section="1">.
4818 <heading>The <file>shlibs</file> File Format</heading>
4821 Each <file>shlibs</file> file has the same format. Lines
4822 beginning with <tt>#</tt> are considered to be comments and
4823 are ignored. Each line is of the form:
4824 <example compact="compact">
4825 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4830 We will explain this by reference to the example of the
4831 <tt>zlib1g</tt> package, which (at the time of writing)
4832 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4836 <var>library-name</var> is the name of the shared library,
4837 in this case <tt>libz</tt>. (This must match the name part
4838 of the soname, see below.)
4842 <var>soname-version-number</var> is the version part of the
4843 soname of the library. The soname is the thing that must
4844 exactly match for the library to be recognized by the
4845 dynamic linker, and is usually of the form
4846 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4847 example, <tt>libz.so.1</tt>.<footnote>
4848 This can be determined using the command
4849 <example compact="compact">
4850 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4853 The version part is the part which comes after
4854 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4858 <var>dependencies</var> has the same syntax as a dependency
4859 field in a binary package control file. It should give
4860 details of which packages are required to satisfy a binary
4861 built against the version of the library contained in the
4862 package. See <ref id="depsyntax"> for details.
4866 In our example, if the first version of the <tt>zlib1g</tt>
4867 package which contained a minor number of at least
4868 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4869 <tt>shlibs</tt> entry for this library could say:
4870 <example compact="compact">
4871 libz 1 zlib1g (>= 1:1.1.3)
4873 The version-specific dependency is to avoid warnings from
4874 the dynamic linker about using older shared libraries with
4880 <heading>Providing a <file>shlibs</file> file</heading>
4883 If your package provides a shared library, you should create
4884 a <file>shlibs</file> file following the format described above.
4885 It is usual to call this file <file>debian/shlibs</file> (but if
4886 you have multiple binary packages, you might want to call it
4887 <file>debian/shlibs.<var>package</var></file> instead). Then
4888 let <file>debian/rules</file> install it in the control area:
4889 <example compact="compact">
4890 install -m644 debian/shlibs debian/tmp/DEBIAN
4892 or, in the case of a multi-binary package:
4893 <example compact="compact">
4894 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4896 An alternative way of doing this is to create the
4897 <file>shlibs</file> file in the control area directly from
4898 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4899 file at all,<footnote>
4900 This is what <prgn>dh_makeshlibs</prgn> in the
4901 <tt>debhelper</tt> suite does.
4903 since the <file>debian/shlibs</file> file itself is ignored by
4904 <prgn>dpkg-shlibdeps</prgn>.
4908 As <prgn>dpkg-shlibdeps</prgn> reads the
4909 <file>DEBIAN/shlibs</file> files in all of the binary packages
4910 being built from this source package, all of the
4911 <file>DEBIAN/shlibs</file> files should be installed before
4912 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4917 <sect1 id="shlibslocal">
4918 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4921 This file is intended only as a <em>temporary</em> fix if
4922 your binaries or libraries depend on a library whose package
4923 does not yet provide a correct <file>shlibs</file> file.
4927 We will assume that you are trying to package a binary
4928 <tt>foo</tt>. When you try running
4929 <prgn>dpkg-shlibdeps</prgn> you get the following error
4930 message (<tt>-O</tt> displays the dependency information on
4931 <tt>stdout</tt> instead of writing it to
4932 <tt>debian/substvars</tt>, and the lines have been wrapped
4933 for ease of reading):
4934 <example compact="compact">
4935 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4936 dpkg-shlibdeps: warning: unable to find dependency
4937 information for shared library libbar (soname 1,
4938 path /usr/lib/libbar.so.1, dependency field Depends)
4939 shlibs:Depends=libc6 (>= 2.2.2-2)
4941 You can then run <prgn>ldd</prgn> on the binary to find the
4942 full location of the library concerned:
4943 <example compact="compact">
4945 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4946 libc.so.6 => /lib/libc.so.6 (0x40032000)
4947 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4949 So the <prgn>foo</prgn> binary depends on the
4950 <prgn>libbar</prgn> shared library, but no package seems to
4951 provide a <file>*.shlibs</file> file handling
4952 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4953 determine the package responsible:
4954 <example compact="compact">
4955 $ dpkg -S /usr/lib/libbar.so.1
4956 bar1: /usr/lib/libbar.so.1
4957 $ dpkg -s bar1 | grep Version
4960 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4961 is the one we are using. Now we can file a bug against the
4962 <tt>bar1</tt> package and create our own
4963 <file>debian/shlibs.local</file> to locally fix the problem.
4964 Including the following line into your
4965 <file>debian/shlibs.local</file> file:
4966 <example compact="compact">
4967 libbar 1 bar1 (>= 1.0-1)
4969 should allow the package build to work.
4973 As soon as the maintainer of <tt>bar1</tt> provides a
4974 correct <file>shlibs</file> file, you should remove this line
4975 from your <file>debian/shlibs.local</file> file. (You should
4976 probably also then have a versioned <tt>Build-Depends</tt>
4977 on <tt>bar1</tt> to help ensure that others do not have the
4978 same problem building your package.)
4987 <chapt id="opersys"><heading>The Operating System</heading>
4990 <heading>Filesystem hierarchy</heading>
4994 <heading>Filesystem Structure</heading>
4997 The location of all installed files and directories must
4998 comply with the Filesystem Hierarchy Standard (FHS),
4999 version 2.1, except where doing so would violate other
5000 terms of Debian Policy. The version of this document
5001 referred here can be found in the <tt>debian-policy</tt>
5003 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5004 name="FHS (Debian copy)"> alongside this manual (or, if
5005 you have the <package>debian-policy</package> installed,
5007 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5008 (local copy)">). The
5009 latest version, which may be a more recent version, may
5011 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5012 Specific questions about following the standard may be
5013 asked on the <tt>debian-devel</tt> mailing list, or
5014 referred to the FHS mailing list (see the
5015 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5021 <heading>Site-specific programs</heading>
5024 As mandated by the FHS, packages must not place any
5025 files in <file>/usr/local</file>, either by putting them in
5026 the file system archive to be unpacked by <prgn>dpkg</prgn>
5027 or by manipulating them in their maintainer scripts.
5031 However, the package may create empty directories below
5032 <file>/usr/local</file> so that the system administrator knows
5033 where to place site-specific files. These directories
5034 should be removed on package removal if they are
5039 Note, that this applies only to directories <em>below</em>
5040 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5041 Packages must not create sub-directories in the directory
5042 <file>/usr/local</file> itself, except those listed in FHS,
5043 section 4.5. However, you may create directories below
5044 them as you wish. You must not remove any of the
5045 directories listed in 4.5, even if you created them.
5049 Since <file>/usr/local</file> can be mounted read-only from a
5050 remote server, these directories must be created and
5051 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5052 maintainer scripts and not be included in the
5053 <file>.deb</file> archive. These scripts must not fail if
5054 either of these operations fail.
5058 For example, the <tt>emacsen-common</tt> package could
5059 contain something like
5060 <example compact="compact">
5061 if [ ! -e /usr/local/share/emacs ]
5063 if mkdir /usr/local/share/emacs 2>/dev/null
5065 chown root:staff /usr/local/share/emacs
5066 chmod 2775 /usr/local/share/emacs
5070 in its <prgn>postinst</prgn> script, and
5071 <example compact="compact">
5072 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5073 rmdir /usr/local/share/emacs 2>/dev/null || true
5075 in the <prgn>prerm</prgn> script. (Note that this form is
5076 used to ensure that if the script is interrupted, the
5077 directory <file>/usr/local/share/emacs</file> will still be
5082 If you do create a directory in <file>/usr/local</file> for
5083 local additions to a package, you should ensure that
5084 settings in <file>/usr/local</file> take precedence over the
5085 equivalents in <file>/usr</file>.
5089 However, because <file>/usr/local</file> and its contents are
5090 for exclusive use of the local administrator, a package
5091 must not rely on the presence or absence of files or
5092 directories in <file>/usr/local</file> for normal operation.
5096 The <file>/usr/local</file> directory itself and all the
5097 subdirectories created by the package should (by default) have
5098 permissions 2775 (group-writable and set-group-id) and be
5099 owned by <tt>root.staff</tt>.
5104 <heading>The system-wide mail directory</heading>
5106 The system-wide mail directory is <file>/var/mail</file>. This
5107 directory is part of the base system and should not owned
5108 by any particular mail agents. The use of the old
5109 location <file>/var/spool/mail</file> is deprecated, even
5110 though the spool may still be physically located there.
5111 To maintain partial upgrade compatibility for systems
5112 which have <file>/var/spool/mail</file> as their physical mail
5113 spool, packages using <file>/var/mail</file> must depend on
5114 either <package>libc6</package> (>= 2.1.3-13), or on
5115 <package>base-files</package> (>= 2.2.0), or on later
5116 versions of either one of these packages.
5122 <heading>Users and groups</heading>
5125 <heading>Introduction</heading>
5127 The Debian system can be configured to use either plain or
5132 Some user ids (UIDs) and group ids (GIDs) are reserved
5133 globally for use by certain packages. Because some
5134 packages need to include files which are owned by these
5135 users or groups, or need the ids compiled into binaries,
5136 these ids must be used on any Debian system only for the
5137 purpose for which they are allocated. This is a serious
5138 restriction, and we should avoid getting in the way of
5139 local administration policies. In particular, many sites
5140 allocate users and/or local system groups starting at 100.
5144 Apart from this we should have dynamically allocated ids,
5145 which should by default be arranged in some sensible
5146 order, but the behavior should be configurable.
5150 Packages other than <tt>base-passwd</tt> must not modify
5151 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5152 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5157 <heading>UID and GID classes</heading>
5159 The UID and GID numbers are divided into classes as
5165 Globally allocated by the Debian project, the same
5166 on every Debian system. These ids will appear in
5167 the <file>passwd</file> and <file>group</file> files of all
5168 Debian systems, new ids in this range being added
5169 automatically as the <tt>base-passwd</tt> package is
5174 Packages which need a single statically allocated
5175 uid or gid should use one of these; their
5176 maintainers should ask the <tt>base-passwd</tt>
5184 Dynamically allocated system users and groups.
5185 Packages which need a user or group, but can have
5186 this user or group allocated dynamically and
5187 differently on each system, should use <tt>adduser
5188 --system</tt> to create the group and/or user.
5189 <prgn>adduser</prgn> will check for the existence of
5190 the user or group, and if necessary choose an unused
5191 id based on the ranges specified in
5192 <file>adduser.conf</file>.
5196 <tag>1000-29999:</tag>
5199 Dynamically allocated user accounts. By default
5200 <prgn>adduser</prgn> will choose UIDs and GIDs for
5201 user accounts in this range, though
5202 <file>adduser.conf</file> may be used to modify this
5207 <tag>30000-59999:</tag>
5212 <tag>60000-64999:</tag>
5215 Globally allocated by the Debian project, but only
5216 created on demand. The ids are allocated centrally
5217 and statically, but the actual accounts are only
5218 created on users' systems on demand.
5222 These ids are for packages which are obscure or
5223 which require many statically-allocated ids. These
5224 packages should check for and create the accounts in
5225 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5226 <prgn>adduser</prgn> if it has this facility) if
5227 necessary. Packages which are likely to require
5228 further allocations should have a "hole" left after
5229 them in the allocation, to give them room to
5234 <tag>65000-65533:</tag>
5242 User <tt>nobody</tt>. The corresponding gid refers
5243 to the group <tt>nogroup</tt>.
5250 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5251 not</em> be used, because it is the error return
5260 <sect id="sysvinit">
5261 <heading>System run levels and <file>init.d</file> scripts</heading>
5263 <sect1 id="/etc/init.d">
5264 <heading>Introduction</heading>
5267 The <file>/etc/init.d</file> directory contains the scripts
5268 executed by <prgn>init</prgn> at boot time and when the
5269 init state (or "runlevel") is changed (see <manref
5270 name="init" section="8">).
5274 There are at least two different, yet functionally
5275 equivalent, ways of handling these scripts. For the sake
5276 of simplicity, this document describes only the symbolic
5277 link method. However, it must not be assumed by maintainer
5278 scripts that this method is being used, and any automated
5279 manipulation of the various runlevel behaviours by
5280 maintainer scripts must be performed using
5281 <prgn>update-rc.d</prgn> as described below and not by
5282 manually installing or removing symlinks. For information
5283 on the implementation details of the other method,
5284 implemented in the <tt>file-rc</tt> package, please refer
5285 to the documentation of that package.
5289 These scripts are referenced by symbolic links in the
5290 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5291 runlevels, <prgn>init</prgn> looks in the directory
5292 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5293 execute, where <tt><var>n</var></tt> is the runlevel that
5294 is being changed to, or <tt>S</tt> for the boot-up
5299 The names of the links all have the form
5300 <file>S<var>mm</var><var>script</var></file> or
5301 <file>K<var>mm</var><var>script</var></file> where
5302 <var>mm</var> is a two-digit number and <var>script</var>
5303 is the name of the script (this should be the same as the
5304 name of the actual script in <file>/etc/init.d</file>).
5308 When <prgn>init</prgn> changes runlevel first the targets
5309 of the links whose names start with a <tt>K</tt> are
5310 executed, each with the single argument <tt>stop</tt>,
5311 followed by the scripts prefixed with an <tt>S</tt>, each
5312 with the single argument <tt>start</tt>. (The links are
5313 those in the <file>/etc/rc<var>n</var>.d</file> directory
5314 corresponding to the new runlevel.) The <tt>K</tt> links
5315 are responsible for killing services and the <tt>S</tt>
5316 link for starting services upon entering the runlevel.
5320 For example, if we are changing from runlevel 2 to
5321 runlevel 3, init will first execute all of the <tt>K</tt>
5322 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5323 all of the <tt>S</tt> prefixed scripts in that directory.
5324 The links starting with <tt>K</tt> will cause the
5325 referred-to file to be executed with an argument of
5326 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5331 The two-digit number <var>mm</var> is used to determine
5332 the order in which to run the scripts: low-numbered links
5333 have their scripts run first. For example, the
5334 <tt>K20</tt> scripts will be executed before the
5335 <tt>K30</tt> scripts. This is used when a certain service
5336 must be started before another. For example, the name
5337 server <prgn>bind</prgn> might need to be started before
5338 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5339 can set up its access lists. In this case, the script
5340 that starts <prgn>bind</prgn> would have a lower number
5341 than the script that starts <prgn>inn</prgn> so that it
5343 <example compact="compact">
5350 The two runlevels 0 (halt) and 6 (reboot) are slightly
5351 different. In these runlevels, the links with an
5352 <tt>S</tt> prefix are still called after those with a
5353 <tt>K</tt> prefix, but they too are called with the single
5354 argument <tt>stop</tt>.
5358 Also, if the script name ends <tt>.sh</tt>, the script
5359 will be sourced in runlevel <tt>S</tt> rather that being
5360 run in a forked subprocess, but will be explicitly run by
5361 <prgn>sh</prgn> in all other runlevels.
5366 <heading>Writing the scripts</heading>
5369 Packages that include daemons for system services should
5370 place scripts in <file>/etc/init.d</file> to start or stop
5371 services at boot time or during a change of runlevel.
5372 These scripts should be named
5373 <file>/etc/init.d/<var>package</var></file>, and they should
5374 accept one argument, saying what to do:
5377 <tag><tt>start</tt></tag>
5378 <item>start the service,</item>
5380 <tag><tt>stop</tt></tag>
5381 <item>stop the service,</item>
5383 <tag><tt>restart</tt></tag>
5384 <item>stop and restart the service if it's already running,
5385 otherwise start the service</item>
5387 <tag><tt>reload</tt></tag>
5388 <item><p>cause the configuration of the service to be
5389 reloaded without actually stopping and restarting
5392 <tag><tt>force-reload</tt></tag>
5393 <item>cause the configuration to be reloaded if the
5394 service supports this, otherwise restart the
5398 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5399 <tt>force-reload</tt> options should be supported by all
5400 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5405 The <file>init.d</file> scripts should ensure that they will
5406 behave sensibly if invoked with <tt>start</tt> when the
5407 service is already running, or with <tt>stop</tt> when it
5408 isn't, and that they don't kill unfortunately-named user
5409 processes. The best way to achieve this is usually to use
5410 <prgn>start-stop-daemon</prgn>.
5414 If a service reloads its configuration automatically (as
5415 in the case of <prgn>cron</prgn>, for example), the
5416 <tt>reload</tt> option of the <file>init.d</file> script
5417 should behave as if the configuration has been reloaded
5422 The <file>/etc/init.d</file> scripts must be treated as
5423 configuration files, either (if they are present in the
5424 package, that is, in the .deb file) by marking them as
5425 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5426 by managing them correctly in the maintainer scripts (see
5427 <ref id="config-files">). This is important since we want
5428 to give the local system administrator the chance to adapt
5429 the scripts to the local system, e.g., to disable a
5430 service without de-installing the package, or to specify
5431 some special command line options when starting a service,
5432 while making sure her changes aren't lost during the next
5437 These scripts should not fail obscurely when the
5438 configuration files remain but the package has been
5439 removed, as configuration files remain on the system after
5440 the package has been removed. Only when <prgn>dpkg</prgn>
5441 is executed with the <tt>--purge</tt> option will
5442 configuration files be removed. In particular, as the
5443 <file>/etc/init.d/<var>package</var></file> script itself is
5444 usually a <tt>conffile</tt>, it will remain on the system
5445 if the package is removed but not purged. Therefore, you
5446 should include a <tt>test</tt> statement at the top of the
5448 <example compact="compact">
5449 test -f <var>program-executed-later-in-script</var> || exit 0
5454 Often there are some variables in the <file>init.d</file>
5455 scripts whose values control the behaviour of the scripts,
5456 and which a system administrator is likely to want to
5457 change. As the scripts themselves are frequently
5458 <tt>conffile</tt>s, modifying them requires that the
5459 administrator merge in their changes each time the package
5460 is upgraded and the <tt>conffile</tt> changes. To ease
5461 the burden on the system administrator, such configurable
5462 values should not be placed directly in the script.
5463 Instead, they should be placed in a file in
5464 <file>/etc/default</file>, which typically will have the same
5465 base name as the <file>init.d</file> script. This extra file
5466 should be sourced by the script when the script runs. It
5467 must contain only variable settings and comments in POSIX
5468 <prgn>sh</prgn> format. It may either be a
5469 <tt>conffile</tt> or a configuration file maintained by
5470 the package maintainer scripts. See <ref id="config-files">
5475 To ensure that vital configurable values are always
5476 available, the <file>init.d</file> script should set default
5477 values for each of the shell variables it uses, either
5478 before sourcing the <file>/etc/default/</file> file or
5479 afterwards using something like the <tt>:
5480 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5481 script must behave sensibly and not fail if the
5482 <file>/etc/default</file> file is deleted.
5487 <heading>Interfacing with the initscript system</heading>
5490 Maintainers should use the abstraction layer provided by
5491 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5492 programs to deal with initscripts in their packages'
5493 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5494 and <prgn>postrm</prgn>.
5498 Directly managing the /etc/rc?.d links and directly
5499 invoking the <file>/etc/init.d/</file> initscripts should
5500 be done only by packages providing the initscript
5501 subsystem (such as <prgn>sysv-rc</prgn> and
5502 <prgn>file-rc</prgn>).
5506 <heading>Managing the links</heading>
5509 The program <prgn>update-rc.d</prgn> is provided for
5510 package maintainers to arrange for the proper creation and
5511 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5512 or their functional equivalent if another method is being
5513 used. This may be used by maintainers in their packages'
5514 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5518 You must not include any <file>/etc/rc<var>n</var>.d</file>
5519 symbolic links in the actual archive or manually create or
5520 remove the symbolic links in maintainer scripts; you must
5521 use the <prgn>update-rc.d</prgn> program instead. (The
5522 former will fail if an alternative method of maintaining
5523 runlevel information is being used.) You must not include
5524 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5525 in the archive either. (Only the <tt>sysvinit</tt>
5530 By default <prgn>update-rc.d</prgn> will start services in
5531 each of the multi-user state runlevels (2, 3, 4, and 5)
5532 and stop them in the halt runlevel (0), the single-user
5533 runlevel (1) and the reboot runlevel (6). The system
5534 administrator will have the opportunity to customize
5535 runlevels by simply adding, moving, or removing the
5536 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5537 symbolic links are being used, or by modifying
5538 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5543 To get the default behavior for your package, put in your
5544 <prgn>postinst</prgn> script
5545 <example compact="compact">
5546 update-rc.d <var>package</var> defaults
5548 and in your <prgn>postrm</prgn>
5549 <example compact="compact">
5550 if [ "$1" = purge ]; then
5551 update-rc.d <var>package</var> remove
5553 </example>. Note that if your package changes runlevels
5554 or priority, you may have to remove and recreate the links,
5555 since otherwise the old links may persist. Refer to the
5556 documentation of <prgn>update-rc.d</prgn>.
5560 This will use a default sequence number of 20. If it does
5561 not matter when or in which order the <file>init.d</file>
5562 script is run, use this default. If it does, then you
5563 should talk to the maintainer of the <prgn>sysvinit</prgn>
5564 package or post to <tt>debian-devel</tt>, and they will
5565 help you choose a number.
5569 For more information about using <tt>update-rc.d</tt>,
5570 please consult its man page <manref name="update-rc.d"
5576 <heading>Running initscripts</heading>
5578 The program <prgn>invoke-rc.d</prgn> is provided to make
5579 it easier for package maintainers to properly invoke an
5580 initscript, obeying runlevel and other locally-defined
5581 constraints that might limit a package's right to start,
5582 stop and otherwise manage services. This program may be
5583 used by maintainers in their packages' scripts.
5587 The use of <prgn>invoke-rc.d</prgn> to invoke the
5588 <file>/etc/init.d/*</file> initscripts is strongly
5589 recommended<footnote>
5590 In the future, the use of invoke-rc.d to invoke
5591 initscripts shall be made mandatory. Maintainers are
5592 advised to switch to invoke-rc.d as soon as
5594 </footnote>, instead of calling them directly.
5598 By default, <prgn>invoke-rc.d</prgn> will pass any
5599 action requests (start, stop, reload, restart...) to the
5600 <file>/etc/init.d</file> script, filtering out requests
5601 to start or restart a service out of its intended
5606 Most packages will simply need to change:
5607 <example compact="compact">/etc/init.d/<package>
5608 <action></example> in their <prgn>postinst</prgn>
5609 and <prgn>prerm</prgn> scripts to:
5610 <example compact="compact">
5611 if command -v invoke-rc.d >/dev/null 2>&1; then
5612 invoke-rc.d <var>package</var> <action>
5614 /etc/init.d/<var>package</var> <action>
5620 A package should register its initscript services using
5621 <prgn>update-rc.d</prgn> before it tries to invoke them
5622 using <prgn>invoke-rc.d</prgn>. Invocation of
5623 unregistered services may fail.
5627 For more information about using
5628 <prgn>invoke-rc.d</prgn>, please consult its man page
5629 <manref name="invoke-rc.d" section="8">.
5635 <heading>Boot-time initialization</heading>
5638 There used to be another directory, <file>/etc/rc.boot</file>,
5639 which contained scripts which were run once per machine
5640 boot. This has been deprecated in favour of links from
5641 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5642 described in <ref id="/etc/init.d">. Packages must not
5643 place files in <file>/etc/rc.boot</file>.
5648 <heading>Example</heading>
5651 The <prgn>bind</prgn> DNS (nameserver) package wants to
5652 make sure that the nameserver is running in multiuser
5653 runlevels, and is properly shut down with the system. It
5654 puts a script in <file>/etc/init.d</file>, naming the script
5655 appropriately <tt>bind</tt>. As you can see, the script
5656 interprets the argument <tt>reload</tt> to send the
5657 nameserver a <tt>HUP</tt> signal (causing it to reload its
5658 configuration); this way the system administrator can say
5659 <tt>/etc/init.d/bind reload</tt> to reload the name
5660 server. The script has one configurable value, which can
5661 be used to pass parameters to the named program at
5662 startup; this value is read from
5663 <file>/etc/default/bind</file> (see below).
5667 <example compact="compact">
5670 # Original version by Robert Leslie
5671 # <rob@mars.org>, edited by iwj and cs
5673 test -x /usr/sbin/named || exit 0
5675 # Source defaults file.
5677 if [ -f /etc/default/bind ]; then
5684 echo -n "Starting domain name service: named"
5685 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5690 echo -n "Stopping domain name service: named"
5691 start-stop-daemon --stop --quiet \
5692 --pidfile /var/run/named.pid --exec /usr/sbin/named
5696 echo -n "Restarting domain name service: named"
5697 start-stop-daemon --stop --quiet --oknodo \
5698 --pidfile /var/run/named.pid --exec /usr/sbin/named
5699 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5703 force-reload|reload)
5704 echo -n "Reloading configuration of domain name service: named"
5705 start-stop-daemon --stop --signal 1 --quiet \
5706 --pidfile /var/run/named.pid --exec /usr/sbin/named
5710 echo "Usage: /etc/init.d/bind " \
5711 " {start|stop|restart|reload|force-reload}" >&2
5721 Complementing the above init script is a configuration
5722 file <file>/etc/default/bind</file>, which contains
5723 configurable parameters used by the script. This would be
5724 created by the <prgn>postinst</prgn> script if it was not
5725 already present, and removed on purge by the
5726 <prgn>postrm</prgn> script.
5727 <example compact="compact">
5728 # Specified parameters to pass to named. See named(8).
5729 # You may uncomment the following line, and edit to taste.
5735 Another example on which you can base your
5736 <file>/etc/init.d</file> scripts is found in
5737 <file>/etc/init.d/skeleton</file>.
5741 If this package is happy with the default setup from
5742 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5743 and having named running in all runlevels, it can say in
5744 its <prgn>postinst</prgn>:
5745 <example compact="compact">
5746 update-rc.d bind defaults >/dev/null
5748 And in its <prgn>postrm</prgn>, to remove the links when the
5750 <example compact="compact">
5751 if [ "$1" = purge ]; then
5752 update-rc.d bind remove >/dev/null
5760 <heading>Console messages from <file>init.d</file> scripts</heading>
5763 This section describes the formats to be used for messages
5764 written to standard output by the <file>/etc/init.d</file>
5765 scripts. The intent is to improve the consistency of
5766 Debian's startup and shutdown look and feel. For this
5767 reason, please look very carefully at the details. We want
5768 the messages to have the same format in terms of wording,
5769 spaces, punctuation and case of letters.
5773 Here is a list of overall rules that you should use when you
5774 create output messages. They can be useful if you have a
5775 non-standard message that is not covered specifically in the
5782 Every message should fit in one line (fewer than 80
5783 characters), start with a capital letter and end with
5784 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5788 If you want to express that the computer is working on
5789 something (that is, performing a specific task, not
5790 starting or stopping a program), we use an "ellipsis"
5791 (three dots: <tt>...</tt>). Note that we don't insert
5792 spaces before or after the dots. If the task has been
5793 completed we write <tt>done.</tt> and a line feed.
5797 Design your messages as if the computer is telling you
5798 what he is doing (let him be polite :-), but don't
5799 mention "him" directly. For example, if you think of
5801 <example compact="compact">
5802 I'm starting network daemons: nfsd mountd.
5805 <example compact="compact">
5806 Starting network daemons: nfsd mountd.
5813 There are standard message formats for the following
5814 situations. They should be used by the <tt>init.d</tt>
5821 <p>When daemons are started</p>
5824 If your script starts one or more daemons, the output
5825 should look like this (a single line, no leading
5827 <example compact="compact">
5828 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5830 The <var>description</var> should describe the
5831 subsystem the daemon or set of daemons are part of,
5832 while <var>daemon-1</var> up to <var>daemon-n</var>
5833 denote each daemon's name (typically the file name of
5838 For example, the output of <file>/etc/init.d/lpd</file>
5840 <example compact="compact">
5841 Starting printer spooler: lpd.
5846 This can be achieved by saying
5847 <example compact="compact">
5848 echo -n "Starting printer spooler: lpd"
5849 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5852 in the script. If you have more than one daemon to
5853 start, you should do the following:
5854 <example compact="compact">
5855 echo -n "Starting remote file system services:"
5856 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5857 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5858 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5861 This makes it possible for the user to see what takes
5862 so long and when the final daemon has been started.
5863 You should be careful where to put spaces: in the
5864 example above the system administrator can easily
5865 comment out a line if he don't wants to start a
5866 specific daemon, while the displayed message still
5872 <p>When a system parameter is being set</p>
5875 If you have to set up different system parameters
5876 during the system boot, you should use this format:
5877 <example compact="compact">
5878 Setting <var>parameter</var> to "<var>value</var>".
5883 You can use a statement such as the following to get
5885 <example compact="compact">
5886 echo "Setting DNS domainname to \"$domainname\"."
5891 Note that the same symbol (<tt>"</tt>) is used for the left
5892 and right quotation marks. A grave accent (<tt>`</tt>) is
5893 not a quote character; neither is an apostrophe
5899 <p>When a daemon is stopped or restarted</p>
5902 When you stop or restart a daemon, you should issue a
5903 message identical to the startup message, except that
5904 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5905 or <tt>Restarting</tt> respectively.
5909 For example, stopping the printer daemon will like
5911 <example compact="compact">
5912 Stopping printer spooler: lpd.
5918 <p>When something is executed</p>
5921 There are several examples where you have to run a
5922 program at system startup or shutdown to perform a
5923 specific task, for example, setting the system's clock
5924 using <prgn>netdate</prgn> or killing all processes
5925 when the system shuts down. Your message should look
5927 <example compact="compact">
5928 Doing something very useful...done.
5930 You should print the <tt>done.</tt> immediately after
5931 the job has been completed, so that the user is
5932 informed why she has to wait. You can get this
5934 <example compact="compact">
5935 echo -n "Doing something very useful..."
5944 <p>When the configuration is reloaded</p>
5947 When a daemon is forced to reload its configuration
5948 files you should use the following format:
5949 <example compact="compact">
5950 Reloading <var>description</var> configuration...done.
5952 where <var>description</var> is the same as in the
5953 daemon starting message.
5961 <heading>Cron jobs</heading>
5964 Packages must not modify the configuration file
5965 <file>/etc/crontab</file>, and they must not modify the files in
5966 <file>/var/spool/cron/crontabs</file>.</p>
5969 If a package wants to install a job that has to be executed
5970 via cron, it should place a file with the name of the
5971 package in one or more of the following directories:
5972 <example compact="compact">
5977 As these directory names imply, the files within them are
5978 executed on a daily, weekly, or monthly basis,
5979 respectively. The exact times are listed in
5980 <file>/etc/crontab</file>.</p>
5983 All files installed in any of these directories must be
5984 scripts (e.g., shell scripts or Perl scripts) so that they
5985 can easily be modified by the local system administrator.
5986 In addition, they should be treated as configuration
5991 If a certain job has to be executed more frequently than
5992 daily, the package should install a file
5993 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5994 same syntax as <file>/etc/crontab</file> and is processed by
5995 <prgn>cron</prgn> automatically. The file must also be
5996 treated as a configuration file. (Note that entries in the
5997 <file>/etc/cron.d</file> directory are not handled by
5998 <prgn>anacron</prgn>. Thus, you should only use this
5999 directory for jobs which may be skipped if the system is not
6003 The scripts or crontab entries in these directories should
6004 check if all necessary programs are installed before they
6005 try to execute them. Otherwise, problems will arise when a
6006 package was removed but not purged since configuration files
6007 are kept on the system in this situation.</p>
6011 <heading>Menus</heading>
6014 The Debian <tt>menu</tt> package provides a standard
6015 interface between packages providing applications and
6016 documents, and <em>menu programs</em> (either X window
6017 managers or text-based menu programs such as
6018 <prgn>pdmenu</prgn>).
6022 All packages that provide applications that need not be
6023 passed any special command line arguments for normal
6024 operation should register a menu entry for those
6025 applications, so that users of the <tt>menu</tt> package
6026 will automatically get menu entries in their window
6027 managers, as well in shells like <tt>pdmenu</tt>.
6031 Menu entries should follow the current menu policy.
6035 The menu policy can be found in the <tt>menu-policy</tt>
6036 files in the <tt>debian-policy</tt> package.
6037 It is also available from the Debian web mirrors at
6038 <tt><url name="/doc/packaging-manuals/menu-policy/"
6039 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6043 Please also refer to the <em>Debian Menu System</em>
6044 documentation that comes with the <tt>menu</tt> package for
6045 information about how to register your applications and web
6051 <heading>Multimedia handlers</heading>
6054 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6055 is a mechanism for encoding files and data streams and
6056 providing meta-information about them, in particular their
6057 type (e.g. audio or video) and format (e.g. PNG, HTML,
6062 Registration of MIME type handlers allows programs like mail
6063 user agents and web browsers to invoke these handlers to
6064 view, edit or display MIME types they don't support directly.
6068 Packages which provide the ability to view/show/play,
6069 compose, edit or print MIME types should register themselves
6070 as such following the current MIME support policy.
6074 The MIME support policy can be found in the <tt>mime-policy</tt>
6075 files in the <tt>debian-policy</tt> package.
6076 It is also available from the Debian web mirrors at
6077 <tt><url name="/doc/packaging-manuals/mime-policy/"
6078 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6084 <heading>Keyboard configuration</heading>
6087 To achieve a consistent keyboard configuration so that all
6088 applications interpret a keyboard event the same way, all
6089 programs in the Debian distribution must be configured to
6090 comply with the following guidelines.
6094 The following keys must have the specified interpretations:
6097 <tag><tt><--</tt></tag>
6098 <item>delete the character to the left of the cursor</item>
6100 <tag><tt>Delete</tt></tag>
6101 <item>delete the character to the right of the cursor</item>
6103 <tag><tt>Control+H</tt></tag>
6104 <item>emacs: the help prefix</item>
6107 The interpretation of any keyboard events should be
6108 independent of the terminal that is used, be it a virtual
6109 console, an X terminal emulator, an rlogin/telnet session,
6114 The following list explains how the different programs
6115 should be set up to achieve this:
6121 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6125 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6129 X translations are set up to make
6130 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6131 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6132 is the vt220 escape code for the "delete character"
6133 key). This must be done by loading the X resources
6134 using <prgn>xrdb</prgn> on all local X displays, not
6135 using the application defaults, so that the
6136 translation resources used correspond to the
6137 <prgn>xmodmap</prgn> settings.
6141 The Linux console is configured to make
6142 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6143 generate <tt>ESC [ 3 ~</tt>.
6147 X applications are configured so that <tt><</tt>
6148 deletes left, and <tt>Delete</tt> deletes right. Motif
6149 applications already work like this.
6153 Terminals should have <tt>stty erase ^?</tt> .
6157 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6158 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6159 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6163 Emacs is programmed to map <tt>KB_Backspace</tt> or
6164 the <tt>stty erase</tt> character to
6165 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6166 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6167 <tt>^H</tt> to <tt>help</tt> as always.
6171 Other applications use the <tt>stty erase</tt>
6172 character and <tt>kdch1</tt> for the two delete keys,
6173 with ASCII DEL being "delete previous character" and
6174 <tt>kdch1</tt> being "delete character under
6182 This will solve the problem except for the following
6189 Some terminals have a <tt><--</tt> key that cannot
6190 be made to produce anything except <tt>^H</tt>. On
6191 these terminals Emacs help will be unavailable on
6192 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6193 character takes precedence in Emacs, and has been set
6194 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6195 available) can be used instead.
6199 Some operating systems use <tt>^H</tt> for <tt>stty
6200 erase</tt>. However, modern telnet versions and all
6201 rlogin versions propagate <tt>stty</tt> settings, and
6202 almost all UNIX versions honour <tt>stty erase</tt>.
6203 Where the <tt>stty</tt> settings are not propagated
6204 correctly, things can be made to work by using
6205 <tt>stty</tt> manually.
6209 Some systems (including previous Debian versions) use
6210 <prgn>xmodmap</prgn> to arrange for both
6211 <tt><--</tt> and <tt>Delete</tt> to generate
6212 <tt>KB_Delete</tt>. We can change the behavior of
6213 their X clients using the same X resources that we use
6214 to do it for our own clients, or configure our clients
6215 using their resources when things are the other way
6216 around. On displays configured like this
6217 <tt>Delete</tt> will not work, but <tt><--</tt>
6222 Some operating systems have different <tt>kdch1</tt>
6223 settings in their <tt>terminfo</tt> database for
6224 <tt>xterm</tt> and others. On these systems the
6225 <tt>Delete</tt> key will not work correctly when you
6226 log in from a system conforming to our policy, but
6227 <tt><--</tt> will.
6234 <heading>Environment variables</heading>
6237 A program must not depend on environment variables to get
6238 reasonable defaults. (That's because these environment
6239 variables would have to be set in a system-wide
6240 configuration file like <file>/etc/profile</file>, which is not
6241 supported by all shells.)
6245 If a program usually depends on environment variables for its
6246 configuration, the program should be changed to fall back to
6247 a reasonable default configuration if these environment
6248 variables are not present. If this cannot be done easily
6249 (e.g., if the source code of a non-free program is not
6250 available), the program must be replaced by a small
6251 "wrapper" shell script which sets the environment variables
6252 if they are not already defined, and calls the original program.
6256 Here is an example of a wrapper script for this purpose:
6258 <example compact="compact">
6260 BAR=${BAR:-/var/lib/fubar}
6262 exec /usr/lib/foo/foo "$@"
6267 Furthermore, as <file>/etc/profile</file> is a configuration
6268 file of the <prgn>base-files</prgn> package, other packages must
6269 not put any environment variables or other commands into that
6278 <heading>Files</heading>
6281 <heading>Binaries</heading>
6284 Two different packages must not install programs with
6285 different functionality but with the same filenames. (The
6286 case of two programs having the same functionality but
6287 different implementations is handled via "alternatives" or
6288 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6289 <ref id="conflicts"> respectively.) If this case happens,
6290 one of the programs must be renamed. The maintainers should
6291 report this to the <tt>debian-devel</tt> mailing list and
6292 try to find a consensus about which program will have to be
6293 renamed. If a consensus cannot be reached, <em>both</em>
6294 programs must be renamed.
6298 By default, when a package is being built, any binaries
6299 created should include debugging information, as well as
6300 being compiled with optimization. You should also turn on
6301 as many reasonable compilation warnings as possible; this
6302 makes life easier for porters, who can then look at build
6303 logs for possible problems. For the C programming language,
6304 this means the following compilation parameters should be
6306 <example compact="compact">
6308 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6310 install -s # (or use strip on the files in debian/tmp)
6315 Note that by default all installed binaries should be stripped,
6316 either by using the <tt>-s</tt> flag to
6317 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6318 the binaries after they have been copied into
6319 <file>debian/tmp</file> but before the tree is made into a
6324 Although binaries in the build tree should be compiled with
6325 debugging information by default, it can often be difficult
6326 to debug programs if they are also subjected to compiler
6327 optimization. For this reason, it is recommended to support
6328 the standardized environment
6329 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6330 contain several flags to change how a package is compiled
6338 The presence of this string means that the package
6339 should be compiled with a minimum of optimization.
6340 For C programs, it is best to add <tt>-O0</tt>
6341 to <tt>CFLAGS</tt> (although this is usually the
6342 default). Some programs might fail to build or run at
6343 this level of optimization; it may be necessary to
6344 use <tt>-O1</tt>, for example.
6348 This string means that the debugging symbols should
6349 not be stripped from the binary during installation,
6350 so that debugging information may be included in the package.
6356 The following makefile snippet is an example of how one may
6357 implement the build options; you will probably have to
6358 massage this example in order to make it work for your
6360 <example compact="compact">
6363 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6364 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6365 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6366 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6368 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6373 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6374 INSTALL_PROGRAM += -s
6380 It is up to the package maintainer to decide what
6381 compilation options are best for the package. Certain
6382 binaries (such as computationally-intensive programs) will
6383 function better with certain flags (<tt>-O3</tt>, for
6384 example); feel free to use them. Please use good judgment
6385 here. Don't use flags for the sake of it; only use them
6386 if there is good reason to do so. Feel free to override
6387 the upstream author's ideas about which compilation
6388 options are best: they are often inappropriate for our
6394 <sect id="libraries">
6395 <heading>Libraries</heading>
6398 The shared version of a library must be compiled with
6399 <tt>-fPIC</tt>, and the static version must not be. In other
6400 words, each source unit (<tt>*.c</tt>, for example, for C files)
6401 will need to be compiled twice.
6405 You must specify the gcc option <tt>-D_REENTRANT</tt>
6406 when building a library (either static or shared) to make
6407 the library compatible with LinuxThreads.
6411 Although not enforced by the build tools, shared libraries
6412 must be linked against all libraries that they use symbols from
6413 in the same way that binaries are. This ensures the correct
6414 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6415 system and guarantees that all libraries can be safely opened
6416 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6417 option <tt>-Wl,-z,defs</tt> when building a shared library.
6418 Since this option enforces symbol resolution at build time,
6419 a missing library reference will be caught early as a fatal
6424 All installed shared libraries should be stripped with
6425 <example compact="compact">
6426 strip --strip-unneeded <var>your-lib</var>
6428 (The option <tt>--strip-unneeded</tt> makes
6429 <prgn>strip</prgn> remove only the symbols which aren't
6430 needed for relocation processing.) Shared libraries can
6431 function perfectly well when stripped, since the symbols for
6432 dynamic linking are in a separate part of the ELF object
6434 You might also want to use the options
6435 <tt>--remove-section=.comment</tt> and
6436 <tt>--remove-section=.note</tt> on both shared libraries
6437 and executables, and <tt>--strip-debug</tt> on static
6443 Note that under some circumstances it may be useful to
6444 install a shared library unstripped, for example when
6445 building a separate package to support debugging.
6449 Shared object files (often <file>.so</file> files) that are not
6450 public libraries, that is, they are not meant to be linked
6451 to by third party executables (binaries of other packages),
6452 should be installed in subdirectories of the
6453 <file>/usr/lib</file> directory. Such files are exempt from the
6454 rules that govern ordinary shared libraries, except that
6455 they must not be installed executable and should be
6457 A common example are the so-called "plug-ins",
6458 internal shared objects that are dynamically loaded by
6459 programs using <manref name="dlopen" section="3">.
6464 Packages containing shared libraries that may be linked to
6465 by other packages' binaries, but which for some
6466 <em>compelling</em> reason can not be installed in
6467 <file>/usr/lib</file> directory, may install the shared library
6468 files in subdirectories of the <file>/usr/lib</file> directory,
6469 in which case they should arrange to add that directory in
6470 <file>/etc/ld.so.conf</file> in the package's post-installation
6471 script, and remove it in the package's post-removal script.
6475 An ever increasing number of packages are using
6476 <prgn>libtool</prgn> to do their linking. The latest GNU
6477 libtools (>= 1.3a) can take advantage of the metadata in the
6478 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6479 files). The main advantage of <prgn>libtool</prgn>'s
6480 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6481 store and subsequently access metadata with respect to the
6482 libraries it builds. <prgn>libtool</prgn> will search for
6483 those files, which contain a lot of useful information about
6484 a library (such as library dependency information for static
6485 linking). Also, they're <em>essential</em> for programs
6486 using <tt>libltdl</tt>.<footnote>
6487 Although <prgn>libtool</prgn> is fully capable of
6488 linking against shared libraries which don't have
6489 <tt>.la</tt> files, as it is a mere shell script it can
6490 add considerably to the build time of a
6491 <prgn>libtool</prgn>-using package if that shell script
6492 has to derive all this information from first principles
6493 for each library every time it is linked. With the
6494 advent of <prgn>libtool</prgn> version 1.4 (and to a
6495 lesser extent <prgn>libtool</prgn> version 1.3), the
6496 <file>.la</file> files also store information about
6497 inter-library dependencies which cannot necessarily be
6498 derived after the <file>.la</file> file is deleted.
6503 Packages that use <prgn>libtool</prgn> to create shared
6504 libraries should include the <file>.la</file> files in the
6505 <tt>-dev</tt> package, unless the package relies on
6506 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6507 the <tt>.la</tt> files must go in the run-time library
6512 You must make sure that you use only released versions of
6513 shared libraries to build your packages; otherwise other
6514 users will not be able to run your binaries
6515 properly. Producing source packages that depend on
6516 unreleased compilers is also usually a bad
6523 <heading>Shared libraries</heading>
6525 This section has moved to <ref id="sharedlibs">.
6531 <heading>Scripts</heading>
6534 All command scripts, including the package maintainer
6535 scripts inside the package and used by <prgn>dpkg</prgn>,
6536 should have a <tt>#!</tt> line naming the shell to be used
6541 In the case of Perl scripts this should be
6542 <tt>#!/usr/bin/perl</tt>.
6546 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6547 should almost certainly start with <tt>set -e</tt> so that
6548 errors are detected. Every script should use
6549 <tt>set -e</tt> or check the exit status of <em>every</em>
6554 The standard shell interpreter <file>/bin/sh</file> can be a
6555 symbolic link to any POSIX compatible shell, if <tt>echo
6556 -n</tt> does not generate a newline.<footnote>
6557 Debian policy specifies POSIX behavior for
6558 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6559 use in the Linux community (in particular including this
6560 policy, the Linux kernel source, many Debian scripts,
6561 etc.). This <tt>echo -n</tt> mechanism is valid but not
6562 required under POSIX, hence this explicit addition.
6563 Also, rumour has it that this shall be mandated under
6566 Thus, shell scripts specifying <file>/bin/sh</file> as
6567 interpreter should only use POSIX features. If a script
6568 requires non-POSIX features from the shell interpreter, the
6569 appropriate shell must be specified in the first line of the
6570 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6571 depend on the package providing the shell (unless the shell
6572 package is marked "Essential", as in the case of
6577 You may wish to restrict your script to POSIX features when
6578 possible so that it may use <file>/bin/sh</file> as its
6579 interpreter. If your script works with <prgn>dash</prgn>
6580 (originally called <prgn>ash</prgn>), it's probably POSIX
6581 compliant, but if you are in doubt, use
6582 <file>/bin/bash</file>.
6586 Perl scripts should check for errors when making any
6587 system calls, including <tt>open</tt>, <tt>print</tt>,
6588 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6592 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6593 scripting languages. See <em>Csh Programming Considered
6594 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6595 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
6596 If an upstream package comes with <prgn>csh</prgn> scripts
6597 then you must make sure that they start with
6598 <tt>#!/bin/csh</tt> and make your package depend on the
6599 <prgn>c-shell</prgn> virtual package.
6603 Any scripts which create files in world-writeable
6604 directories (e.g., in <file>/tmp</file>) must use a
6605 mechanism which will fail if a file with the same name
6610 The Debian base system provides the <prgn>tempfile</prgn>
6611 and <prgn>mktemp</prgn> utilities for use by scripts for
6618 <heading>Symbolic links</heading>
6621 In general, symbolic links within a top-level directory
6622 should be relative, and symbolic links pointing from one
6623 top-level directory into another should be absolute. (A
6624 top-level directory is a sub-directory of the root
6625 directory <file>/</file>.)
6629 In addition, symbolic links should be specified as short as
6630 possible, i.e., link targets like <file>foo/../bar</file> are
6635 Note that when creating a relative link using
6636 <prgn>ln</prgn> it is not necessary for the target of the
6637 link to exist relative to the working directory you're
6638 running <prgn>ln</prgn> from, nor is it necessary to change
6639 directory to the directory where the link is to be made.
6640 Simply include the string that should appear as the target
6641 of the link (this will be a pathname relative to the
6642 directory in which the link resides) as the first argument
6647 For example, in your <prgn>Makefile</prgn> or
6648 <file>debian/rules</file>, you can do things like:
6649 <example compact="compact">
6650 ln -fs gcc $(prefix)/bin/cc
6651 ln -fs gcc debian/tmp/usr/bin/cc
6652 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6653 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6658 A symbolic link pointing to a compressed file should always
6659 have the same file extension as the referenced file. (For
6660 example, if a file <file>foo.gz</file> is referenced by a
6661 symbolic link, the filename of the link has to end with
6662 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6667 <heading>Device files</heading>
6670 Packages must not include device files in the package file
6675 If a package needs any special device files that are not
6676 included in the base system, it must call
6677 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6678 after notifying the user<footnote>
6679 This notification could be done via a (low-priority)
6680 debconf message, or an echo (printf) statement.
6685 Packages must not remove any device files in the
6686 <prgn>postrm</prgn> or any other script. This is left to the
6687 system administrator.
6691 Debian uses the serial devices
6692 <file>/dev/ttyS*</file>. Programs using the old
6693 <file>/dev/cu*</file> devices should be changed to use
6694 <file>/dev/ttyS*</file>.
6698 <sect id="config-files">
6699 <heading>Configuration files</heading>
6702 <heading>Definitions</heading>
6706 <tag>configuration file</tag>
6708 A file that affects the operation of a program, or
6709 provides site- or host-specific information, or
6710 otherwise customizes the behavior of a program.
6711 Typically, configuration files are intended to be
6712 modified by the system administrator (if needed or
6713 desired) to conform to local policy or to provide
6714 more useful site-specific behavior.
6717 <tag><tt>conffile</tt></tag>
6719 A file listed in a package's <tt>conffiles</tt>
6720 file, and is treated specially by <prgn>dpkg</prgn>
6721 (see <ref id="configdetails">).
6727 The distinction between these two is important; they are
6728 not interchangeable concepts. Almost all
6729 <tt>conffile</tt>s are configuration files, but many
6730 configuration files are not <tt>conffiles</tt>.
6734 Note that a script that embeds configuration information
6735 (such as most of the files in <file>/etc/default</file> and
6736 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6737 configuration file and should be treated as such.
6742 <heading>Location</heading>
6745 Any configuration files created or used by your package
6746 must reside in <file>/etc</file>. If there are several,
6747 consider creating a subdirectory of <file>/etc</file>
6748 named after your package.
6752 If your package creates or uses configuration files
6753 outside of <file>/etc</file>, and it is not feasible to modify
6754 the package to use <file>/etc</file> directly, put the files
6755 in <file>/etc</file> and create symbolic links to those files
6756 from the location that the package requires.
6761 <heading>Behavior</heading>
6764 Configuration file handling must conform to the following
6766 <list compact="compact">
6768 local changes must be preserved during a package
6772 configuration files must be preserved when the
6773 package is removed, and only deleted when the
6780 The easy way to achieve this behavior is to make the
6781 configuration file a <tt>conffile</tt>. This is
6782 appropriate only if it is possible to distribute a default
6783 version that will work for most installations, although
6784 some system administrators may choose to modify it. This
6785 implies that the default version will be part of the
6786 package distribution, and must not be modified by the
6787 maintainer scripts during installation (or at any other
6792 In order to ensure that local changes are preserved
6793 correctly, no package may contain or make hard links to
6794 conffiles.<footnote>
6795 Rationale: There are two problems with hard links.
6796 The first is that some editors break the link while
6797 editing one of the files, so that the two files may
6798 unwittingly become unlinked and different. The second
6799 is that <prgn>dpkg</prgn> might break the hard link
6800 while upgrading <tt>conffile</tt>s.
6805 The other way to do it is via the maintainer scripts. In
6806 this case, the configuration file must not be listed as a
6807 <tt>conffile</tt> and must not be part of the package
6808 distribution. If the existence of a file is required for
6809 the package to be sensibly configured it is the
6810 responsibility of the package maintainer to provide
6811 maintainer scripts which correctly create, update and
6812 maintain the file and remove it on purge. (See <ref
6813 id="maintainerscripts"> for more information.) These
6814 scripts must be idempotent (i.e., must work correctly if
6815 <prgn>dpkg</prgn> needs to re-run them due to errors
6816 during installation or removal), must cope with all the
6817 variety of ways <prgn>dpkg</prgn> can call maintainer
6818 scripts, must not overwrite or otherwise mangle the user's
6819 configuration without asking, must not ask unnecessary
6820 questions (particularly during upgrades), and otherwise be
6825 The scripts are not required to configure every possible
6826 option for the package, but only those necessary to get
6827 the package running on a given system. Ideally the
6828 sysadmin should not have to do any configuration other
6829 than that done (semi-)automatically by the
6830 <prgn>postinst</prgn> script.
6834 A common practice is to create a script called
6835 <file><var>package</var>-configure</file> and have the
6836 package's <prgn>postinst</prgn> call it if and only if the
6837 configuration file does not already exist. In certain
6838 cases it is useful for there to be an example or template
6839 file which the maintainer scripts use. Such files should
6840 be in <file>/usr/share/<var>package</var></file> or
6841 <file>/usr/lib/<var>package</var></file> (depending on whether
6842 they are architecture-independent or not). There should
6843 be symbolic links to them from
6844 <file>/usr/share/doc/<var>package</var>/examples</file> if
6845 they are examples, and should be perfectly ordinary
6846 <prgn>dpkg</prgn>-handled files (<em>not</em>
6847 configuration files).
6851 These two styles of configuration file handling must
6852 not be mixed, for that way lies madness:
6853 <prgn>dpkg</prgn> will ask about overwriting the file
6854 every time the package is upgraded.
6859 <heading>Sharing configuration files</heading>
6862 Packages which specify the same file as a
6863 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6864 with each other. (This is an instance of the general rule
6865 about not sharing files. Note that neither alternatives
6866 nor diversions are likely to be appropriate in this case;
6867 in particular, <prgn>dpkg</prgn> does not handle diverted
6868 <tt>conffile</tt>s well.)
6872 The maintainer scripts must not alter a <tt>conffile</tt>
6873 of <em>any</em> package, including the one the scripts
6878 If two or more packages use the same configuration file
6879 and it is reasonable for both to be installed at the same
6880 time, one of these packages must be defined as
6881 <em>owner</em> of the configuration file, i.e., it will be
6882 the package which handles that file as a configuration
6883 file. Other packages that use the configuration file must
6884 depend on the owning package if they require the
6885 configuration file to operate. If the other package will
6886 use the configuration file if present, but is capable of
6887 operating without it, no dependency need be declared.
6891 If it is desirable for two or more related packages to
6892 share a configuration file <em>and</em> for all of the
6893 related packages to be able to modify that configuration
6894 file, then the following should be done:
6895 <enumlist compact="compact">
6897 One of the related packages (the "owning" package)
6898 will manage the configuration file with maintainer
6899 scripts as described in the previous section.
6902 The owning package should also provide a program
6903 that the other packages may use to modify the
6907 The related packages must use the provided program
6908 to make any desired modifications to the
6909 configuration file. They should either depend on
6910 the core package to guarantee that the configuration
6911 modifier program is available or accept gracefully
6912 that they cannot modify the configuration file if it
6913 is not. (This is in addition to the fact that the
6914 configuration file may not even be present in the
6921 Sometimes it's appropriate to create a new package which
6922 provides the basic infrastructure for the other packages
6923 and which manages the shared configuration files. (The
6924 <tt>sgml-base</tt> package is a good example.)
6929 <heading>User configuration files ("dotfiles")</heading>
6932 The files in <file>/etc/skel</file> will automatically be
6933 copied into new user accounts by <prgn>adduser</prgn>.
6934 No other program should reference the files in
6935 <file>/etc/skel</file>.
6939 Therefore, if a program needs a dotfile to exist in
6940 advance in <file>$HOME</file> to work sensibly, that dotfile
6941 should be installed in <file>/etc/skel</file> and treated as a
6946 However, programs that require dotfiles in order to
6947 operate sensibly are a bad thing, unless they do create
6948 the dotfiles themselves automatically.
6952 Furthermore, programs should be configured by the Debian
6953 default installation to behave as closely to the upstream
6954 default behaviour as possible.
6958 Therefore, if a program in a Debian package needs to be
6959 configured in some way in order to operate sensibly, that
6960 should be done using a site-wide configuration file placed
6961 in <file>/etc</file>. Only if the program doesn't support a
6962 site-wide default configuration and the package maintainer
6963 doesn't have time to add it may a default per-user file be
6964 placed in <file>/etc/skel</file>.
6968 <file>/etc/skel</file> should be as empty as we can make it.
6969 This is particularly true because there is no easy (or
6970 necessarily desirable) mechanism for ensuring that the
6971 appropriate dotfiles are copied into the accounts of
6972 existing users when a package is installed.
6978 <heading>Log files</heading>
6980 Log files should usually be named
6981 <file>/var/log/<var>package</var>.log</file>. If you have many
6982 log files, or need a separate directory for permission
6983 reasons (<file>/var/log</file> is writable only by
6984 <file>root</file>), you should usually create a directory named
6985 <file>/var/log/<var>package</var></file> and place your log
6990 Log files must be rotated occasionally so that they don't
6991 grow indefinitely; the best way to do this is to drop a log
6992 rotation configuration file into the directory
6993 <file>/etc/logrotate.d</file> and use the facilities provided by
6994 logrotate.<footnote>
6996 The traditional approach to log files has been to set up
6997 <em>ad hoc</em> log rotation schemes using simple shell
6998 scripts and cron. While this approach is highly
6999 customizable, it requires quite a lot of sysadmin work.
7000 Even though the original Debian system helped a little
7001 by automatically installing a system which can be used
7002 as a template, this was deemed not enough.
7006 The use of <prgn>logrotate</prgn>, a program developed
7007 by Red Hat, is better, as it centralizes log management.
7008 It has both a configuration file
7009 (<file>/etc/logrotate.conf</file>) and a directory where
7010 packages can drop their individual log rotation
7011 configurations (<file>/etc/logrotate.d</file>).
7014 Here is a good example for a logrotate config
7015 file (for more information see <manref name="logrotate"
7017 <example compact="compact">
7018 /var/log/foo/*.log {
7023 /etc/init.d/foo force-reload
7027 This rotates all files under <file>/var/log/foo</file>, saves 12
7028 compressed generations, and forces the daemon to reload its
7029 configuration information after the log rotation.
7033 Log files should be removed when the package is
7034 purged (but not when it is only removed). This should be
7035 done by the <prgn>postrm</prgn> script when it is called
7036 with the argument <tt>purge</tt> (see <ref
7037 id="removedetails">).
7042 <heading>Permissions and owners</heading>
7045 The rules in this section are guidelines for general use.
7046 If necessary you may deviate from the details below.
7047 However, if you do so you must make sure that what is done
7048 is secure and you should try to be as consistent as possible
7049 with the rest of the system. You should probably also
7050 discuss it on <prgn>debian-devel</prgn> first.
7054 Files should be owned by <tt>root.root</tt>, and made
7055 writable only by the owner and universally readable (and
7056 executable, if appropriate), that is mode 644 or 755.
7060 Directories should be mode 755 or (for group-writability)
7061 mode 2775. The ownership of the directory should be
7062 consistent with its mode: if a directory is mode 2775, it
7063 should be owned by the group that needs write access to
7068 Setuid and setgid executables should be mode 4755 or 2755
7069 respectively, and owned by the appropriate user or group.
7070 They should not be made unreadable (modes like 4711 or
7071 2711 or even 4111); doing so achieves no extra security,
7072 because anyone can find the binary in the freely available
7073 Debian package; it is merely inconvenient. For the same
7074 reason you should not restrict read or execute permissions
7075 on non-set-id executables.
7079 Some setuid programs need to be restricted to particular
7080 sets of users, using file permissions. In this case they
7081 should be owned by the uid to which they are set-id, and by
7082 the group which should be allowed to execute them. They
7083 should have mode 4754; again there is no point in making
7084 them unreadable to those users who must not be allowed to
7089 It is possible to arrange that the system administrator can
7090 reconfigure the package to correspond to their local
7091 security policy by changing the permissions on a binary:
7092 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7093 described below.<footnote>
7094 Ordinary files installed by <prgn>dpkg</prgn> (as
7095 opposed to <tt>conffile</tt>s and other similar objects)
7096 normally have their permissions reset to the distributed
7097 permissions when the package is reinstalled. However,
7098 the use of <prgn>dpkg-statoverride</prgn> overrides this
7099 default behaviour. If you use this method, you should
7100 remember to describe <prgn>dpkg-statoverride</prgn> in
7101 the package documentation; being a relatively new
7102 addition to Debian, it is probably not yet well-known.
7104 Another method you should consider is to create a group for
7105 people allowed to use the program(s) and make any setuid
7106 executables executable only by that group.
7110 If you need to create a new user or group for your package
7111 there are two possibilities. Firstly, you may need to
7112 make some files in the binary package be owned by this
7113 user or group, or you may need to compile the user or
7114 group id (rather than just the name) into the binary
7115 (though this latter should be avoided if possible, as in
7116 this case you need a statically allocated id).</p>
7119 If you need a statically allocated id, you must ask for a
7120 user or group id from the <tt>base-passwd</tt> maintainer,
7121 and must not release the package until you have been
7122 allocated one. Once you have been allocated one you must
7123 either make the package depend on a version of the
7124 <tt>base-passwd</tt> package with the id present in
7125 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7126 your package to create the user or group itself with the
7127 correct id (using <tt>adduser</tt>) in its
7128 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7129 the <prgn>postinst</prgn> is to be preferred if it is
7130 possible, otherwise a pre-dependency will be needed on the
7131 <tt>adduser</tt> package.)
7135 On the other hand, the program might be able to determine
7136 the uid or gid from the user or group name at runtime, so
7137 that a dynamically allocated id can be used. In this case
7138 you should choose an appropriate user or group name,
7139 discussing this on <prgn>debian-devel</prgn> and checking
7140 with the <package/base-passwd/ maintainer that it is unique and that
7141 they do not wish you to use a statically allocated id
7142 instead. When this has been checked you must arrange for
7143 your package to create the user or group if necessary using
7144 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7145 <prgn>postinst</prgn> script (again, the latter is to be
7146 preferred if it is possible).
7150 Note that changing the numeric value of an id associated
7151 with a name is very difficult, and involves searching the
7152 file system for all appropriate files. You need to think
7153 carefully whether a static or dynamic id is required, since
7154 changing your mind later will cause problems.
7157 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7159 This section is not intended as policy, but as a
7160 description of the use of <prgn>dpkg-statoverride</prgn>.
7164 <prgn>dpkg-statoverride</prgn> is a replacement for the
7165 deprecated <tt>suidmanager</tt> package. Packages which
7166 previously used <tt>suidmanager</tt> should have a
7167 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7168 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7169 and <tt>suidunregister</tt> should now be simply removed
7170 from the maintainer scripts.
7174 If a system administrator wishes to have a file (or
7175 directory or other such thing) installed with owner and
7176 permissions different from those in the distributed Debian
7177 package, he can use the <prgn>dpkg-statoverride</prgn>
7178 program to instruct <prgn>dpkg</prgn> to use the different
7179 settings every time the file is installed. Thus the
7180 package maintainer should distribute the files with their
7181 normal permissions, and leave it for the system
7182 administrator to make any desired changes. For example, a
7183 daemon which is normally required to be setuid root, but
7184 in certain situations could be used without being setuid,
7185 should be installed setuid in the <tt>.deb</tt>. Then the
7186 local system administrator can change this if they wish.
7187 If there are two standard ways of doing it, the package
7188 maintainer can use <tt>debconf</tt> to find out the
7189 preference, and call <prgn>dpkg-statoverride</prgn> in the
7190 maintainer script if necessary to accommodate the system
7191 administrator's choice.
7195 Given the above, <prgn>dpkg-statoverride</prgn> is
7196 essentially a tool for system administrators and would not
7197 normally be needed in the maintainer scripts. There is
7198 one type of situation, though, where calls to
7199 <prgn>dpkg-statoverride</prgn> would be needed in the
7200 maintainer scripts, and that involves packages which use
7201 dynamically allocated user or group ids. In such a
7202 situation, something like the following idiom can be very
7203 helpful in the package's <prgn>postinst</prgn>, where
7204 <tt>sysuser</tt> is a dynamically allocated id:
7206 for i in /usr/bin/foo /usr/sbin/bar
7208 if ! dpkg-statoverride --list $i >/dev/null
7210 dpkg-statoverride --update --add sysuser root 4755 $i
7214 The corresponding <tt>dpkg-statoverride --remove</tt>
7215 calls can then be made unconditionally when the package is
7223 <chapt id="customized-programs">
7224 <heading>Customized programs</heading>
7226 <sect id="arch-spec">
7227 <heading>Architecture specification strings</heading>
7230 If a program needs to specify an <em>architecture specification
7231 string</em> in some place, the following format should be
7232 used: <var>arch</var>-<var>os</var><footnote>
7233 The following architectures and operating systems are
7234 currently recognised by <prgn>dpkg-architecture</prgn>.
7235 The architecture, <tt><var>arch</var></tt>, is one of
7236 the following: <tt>alpha</tt>, <tt>arm</tt>,
7237 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7238 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7239 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7240 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7241 operating system, <tt><var>os</var></tt>, is one of:
7242 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7243 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7244 reserved for the GNU/Hurd operating system.
7249 Note that we don't want to use
7250 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7251 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7252 since this would make our programs incompatible with other
7253 Linux distributions. We also don't use something like
7254 <tt><var>arch</var>-unknown-linux</tt>, since the
7255 <tt>unknown</tt> does not look very good.
7260 <heading>Daemons</heading>
7263 The configuration files <file>/etc/services</file>,
7264 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7265 by the <prgn>netbase</prgn> package and must not be modified
7270 If a package requires a new entry in one of these files, the
7271 maintainer should get in contact with the
7272 <prgn>netbase</prgn> maintainer, who will add the entries
7273 and release a new version of the <prgn>netbase</prgn>
7278 The configuration file <file>/etc/inetd.conf</file> must not be
7279 modified by the package's scripts except via the
7280 <prgn>update-inetd</prgn> script or the
7281 <file>DebianNet.pm</file> Perl module. See their documentation
7282 for details on how to add entries.
7286 If a package wants to install an example entry into
7287 <file>/etc/inetd.conf</file>, the entry must be preceded with
7288 exactly one hash character (<tt>#</tt>). Such lines are
7289 treated as "commented out by user" by the
7290 <prgn>update-inetd</prgn> script and are not changed or
7291 activated during package updates.
7296 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7300 Some programs need to create pseudo-ttys. This should be done
7301 using Unix98 ptys if the C library supports it. The resulting
7302 program must not be installed setuid root, unless that
7303 is required for other functionality.
7307 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7308 <file>/var/log/lastlog</file> must be installed writeable by
7309 group <tt>utmp</tt>. Programs which need to modify those
7310 files must be installed setgid <tt>utmp</tt>.
7315 <heading>Editors and pagers</heading>
7318 Some programs have the ability to launch an editor or pager
7319 program to edit or display a text document. Since there are
7320 lots of different editors and pagers available in the Debian
7321 distribution, the system administrator and each user should
7322 have the possibility to choose his/her preferred editor and
7327 In addition, every program should choose a good default
7328 editor/pager if none is selected by the user or system
7333 Thus, every program that launches an editor or pager must
7334 use the EDITOR or PAGER environment variable to determine
7335 the editor or pager the user wishes to use. If these
7336 variables are not set, the programs <file>/usr/bin/editor</file>
7337 and <file>/usr/bin/pager</file> should be used, respectively.
7341 These two files are managed through the <prgn>dpkg</prgn>
7342 "alternatives" mechanism. Thus every package providing an
7343 editor or pager must call the
7344 <prgn>update-alternatives</prgn> script to register these
7349 If it is very hard to adapt a program to make use of the
7350 EDITOR or PAGER variables, that program may be configured to
7351 use <file>/usr/bin/sensible-editor</file> and
7352 <file>/usr/bin/sensible-pager</file> as the editor or pager
7353 program respectively. These are two scripts provided in the
7354 Debian base system that check the EDITOR and PAGER variables
7355 and launch the appropriate program, and fall back to
7356 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7357 variable is not set.
7361 A program may also use the VISUAL environment variable to
7362 determine the user's choice of editor. If it exists, it
7363 should take precedence over EDITOR. This is in fact what
7364 <file>/usr/bin/sensible-editor</file> does.
7368 It is not required for a package to depend on
7369 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7370 package to provide such virtual packages.<footnote>
7371 The Debian base system already provides an editor and a
7377 <sect id="web-appl">
7378 <heading>Web servers and applications</heading>
7381 This section describes the locations and URLs that should
7382 be used by all web servers and web applications in the
7389 Cgi-bin executable files are installed in the
7391 <example compact="compact">
7392 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7394 and should be referred to as
7395 <example compact="compact">
7396 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7401 <p>Access to HTML documents</p>
7404 HTML documents for a package are stored in
7405 <file>/usr/share/doc/<var>package</var></file>
7406 and can be referred to as
7407 <example compact="compact">
7408 http://localhost/doc/<var>package</var>/<var>filename</var>
7413 The web server should restrict access to the document
7414 tree so that only clients on the same host can read
7415 the documents. If the web server does not support such
7416 access controls, then it should not provide access at
7417 all, or ask about providing access during installation.
7422 <p>Web Document Root</p>
7425 Web Applications should try to avoid storing files in
7426 the Web Document Root. Instead they should use the
7427 /usr/share/doc/<var>package</var> directory for
7428 documents and register the Web Application via the
7429 menu package. If access to the web document root is
7430 unavoidable then use
7431 <example compact="compact">
7434 as the Document Root. This might be just a symbolic
7435 link to the location where the system administrator
7436 has put the real document root.
7444 <sect id="mail-transport-agents">
7445 <heading>Mail transport, delivery and user agents</heading>
7448 Debian packages which process electronic mail, whether mail
7449 user agents (MUAs) or mail transport agents (MTAs), must
7450 ensure that they are compatible with the configuration
7451 decisions below. Failure to do this may result in lost
7452 mail, broken <tt>From:</tt> lines, and other serious brain
7457 The mail spool is <file>/var/mail</file> and the interface to
7458 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7459 the FHS). On older systems, the mail spool may be
7460 physically located in <file>/var/spool/mail</file>, but all
7461 access to the mail spool should be via the
7462 <file>/var/mail</file> symlink. The mail spool is part of the
7463 base system and not part of the MTA package.
7467 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7468 programs (such as IMAP daemons) must lock the mailbox in an
7469 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7470 be combined with dot locking. To avoid deadlocks, a program
7471 should use <tt>fcntl()</tt> first and dot locking after
7472 this, or alternatively implement the two locking methods in
7473 a non blocking way<footnote>
7474 If it is not possible to establish both locks, the
7475 system shouldn't wait for the second lock to be
7476 established, but remove the first lock, wait a (random)
7477 time, and start over locking again.
7478 </footnote>. Using the functions <tt>maillock</tt> and
7479 <tt>mailunlock</tt> provided by the
7480 <tt>liblockfile*</tt><footnote>
7481 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7482 to use these functions.
7483 </footnote> packages is the recommended way to realize this.
7487 Mailboxes are generally mode 660
7488 <tt><var>user</var>.mail</tt> unless the system
7489 administrator has chosen otherwise. A MUA may remove a
7490 mailbox (unless it has nonstandard permissions) in which
7491 case the MTA or another MUA must recreate it if needed.
7492 Mailboxes must be writable by group mail.
7496 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7497 be setgid mail to do the locking mentioned above (and
7498 must obviously avoid accessing other users' mailboxes
7499 using this privilege).</p>
7502 <file>/etc/aliases</file> is the source file for the system mail
7503 aliases (e.g., postmaster, usenet, etc.), it is the one
7504 which the sysadmin and <prgn>postinst</prgn> scripts may
7505 edit. After <file>/etc/aliases</file> is edited the program or
7506 human editing it must call <prgn>newaliases</prgn>. All MTA
7507 packages must come with a <prgn>newaliases</prgn> program,
7508 even if it does nothing, but older MTA packages did not do
7509 this so programs should not fail if <prgn>newaliases</prgn>
7510 cannot be found. Note that because of this, all MTA
7511 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7512 <tt>Replaces: mail-transport-agent</tt> control file
7517 The convention of writing <tt>forward to
7518 <var>address</var></tt> in the mailbox itself is not
7519 supported. Use a <tt>.forward</tt> file instead.</p>
7522 The <prgn>rmail</prgn> program used by UUCP
7523 for incoming mail should be <file>/usr/sbin/rmail</file>.
7524 Likewise, <prgn>rsmtp</prgn>, for receiving
7525 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7529 If your package needs to know what hostname to use on (for
7530 example) outgoing news and mail messages which are generated
7531 locally, you should use the file <file>/etc/mailname</file>. It
7532 will contain the portion after the username and <tt>@</tt>
7533 (at) sign for email addresses of users on the machine
7534 (followed by a newline).
7538 Such package should check for the existence of this file
7539 when it is being configured. If it exists, it should be
7540 used without comment, although an MTA's configuration script
7541 may wish to prompt the user even if it finds that this file
7542 exists. If the file does not exist, the package should
7543 prompt the user for the value (preferably using
7544 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7545 as well as using it in the package's configuration. The
7546 prompt should make it clear that the name will not just be
7547 used by that package. For example, in this situation the
7548 <tt>inn</tt> package could say something like:
7549 <example compact="compact">
7550 Please enter the "mail name" of your system. This is the
7551 hostname portion of the address to be shown on outgoing
7552 news and mail messages. The default is
7553 <var>syshostname</var>, your system's host name. Mail
7554 name ["<var>syshostname</var>"]:
7556 where <var>syshostname</var> is the output of <tt>hostname
7562 <heading>News system configuration</heading>
7565 All the configuration files related to the NNTP (news)
7566 servers and clients should be located under
7567 <file>/etc/news</file>.</p>
7570 There are some configuration issues that apply to a number
7571 of news clients and server packages on the machine. These
7575 <tag><file>/etc/news/organization</file></tag>
7577 A string which should appear as the
7578 organization header for all messages posted
7579 by NNTP clients on the machine
7582 <tag><file>/etc/news/server</file></tag>
7584 Contains the FQDN of the upstream NNTP
7585 server, or localhost if the local machine is
7590 Other global files may be added as required for cross-package news
7597 <heading>Programs for the X Window System</heading>
7600 <heading>Providing X support and package priorities</heading>
7603 Programs that can be configured with support for the X
7604 Window System must be configured to do so and must declare
7605 any package dependencies necessary to satisfy their
7606 runtime requirements when using the X Window System. If
7607 such a package is of higher priority than the X packages
7608 on which it depends, it is required that either the
7609 X-specific components be split into a separate package, or
7610 that an alternative version of the package, which includes
7611 X support, be provided, or that the package's priority be
7617 <heading>Packages providing an X server</heading>
7620 Packages that provide an X server that, directly or
7621 indirectly, communicates with real input and display
7622 hardware should declare in their control data that they
7623 provide the virtual package <tt>xserver</tt>.<footnote>
7624 This implements current practice, and provides an
7625 actual policy for usage of the <tt>xserver</tt>
7626 virtual package which appears in the virtual packages
7627 list. In a nutshell, X servers that interface
7628 directly with the display and input hardware or via
7629 another subsystem (e.g., GGI) should provide
7630 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7631 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7637 <heading>Packages providing a terminal emulator</heading>
7640 Packages that provide a terminal emulator for the X Window
7641 System which meet the criteria listed below should declare
7642 in their control data that they provide the virtual
7643 package <tt>x-terminal-emulator</tt>. They should also
7644 register themselves as an alternative for
7645 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7650 To be an <tt>x-terminal-emulator</tt>, a program must:
7651 <list compact="compact">
7653 Be able to emulate a DEC VT100 terminal, or a
7654 compatible terminal.
7658 Support the command-line option <tt>-e
7659 <var>command</var></tt>, which creates a new
7660 terminal window<footnote>
7661 "New terminal window" does not necessarily mean
7662 a new top-level X window directly parented by
7663 the window manager; it could, if the terminal
7664 emulator application were so coded, be a new
7665 "view" in a multiple-document interface (MDI).
7667 and runs the specified <var>command</var>,
7668 interpreting the entirity of the rest of the command
7669 line as a command to pass straight to exec, in the
7670 manner that <tt>xterm</tt> does.
7674 Support the command-line option <tt>-T
7675 <var>title</var></tt>, which creates a new terminal
7676 window with the window title <var>title</var>.
7683 <heading>Packages providing a window manager</heading>
7686 Packages that provide a window manager should declare in
7687 their control data that they provide the virtual package
7688 <tt>x-window-manager</tt>. They should also register
7689 themselves as an alternative for
7690 <file>/usr/bin/x-window-manager</file>, with a priority
7691 calculated as follows:
7692 <list compact="compact">
7694 Start with a priority of 20.
7698 If the window manager supports the Debian menu
7699 system, add 20 points if this support is available
7700 in the package's default configuration (i.e., no
7701 configuration files belonging to the system or user
7702 have to be edited to activate the feature); if
7703 configuration files must be modified, add only 10
7709 If the window manager complies with <url
7710 id="http://www.freedesktop.org/Standards/wm-spec"
7711 name="The Window Manager Specification Project">,
7712 written by the <url id="http://www.freedesktop.org/"
7713 name="Free Desktop Group">, add 40 points.
7717 If the window manager permits the X session to be
7718 restarted using a <em>different</em> window manager
7719 (without killing the X server) in its default
7720 configuration, add 10 points; otherwise add none.
7727 <heading>Packages providing fonts</heading>
7730 Packages that provide fonts for the X Window
7732 For the purposes of Debian Policy, a "font for the X
7733 Window System" is one which is accessed via X protocol
7734 requests. Fonts for the Linux console, for PostScript
7735 renderers, or any other purpose, do not fit this
7736 definition. Any tool which makes such fonts available
7737 to the X Window System, however, must abide by this
7740 must do a number of things to ensure that they are both
7741 available without modification of the X or font server
7742 configuration, and that they do not corrupt files used by
7743 other font packages to register information about
7747 Fonts of any type supported by the X Window System
7748 must be in a separate binary package from any
7749 executables, libraries, or documentation (except
7750 that specific to the fonts shipped, such as their
7751 license information). If one or more of the fonts
7752 so packaged are necessary for proper operation of
7753 the package with which they are associated the font
7754 package may be Recommended; if the fonts merely
7755 provide an enhancement, a Suggests relationship may
7756 be used. Packages must not Depend on font
7758 This is because the X server may retrieve fonts
7759 from the local filesystem or over the network
7760 from an X font server; the Debian package system
7761 is empowered to deal only with the local
7767 BDF fonts must be converted to PCF fonts with the
7768 <prgn>bdftopcf</prgn> utility (available in the
7769 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7770 placed in a directory that corresponds to their
7772 <list compact="compact">
7774 100 dpi fonts must be placed in
7775 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7779 75 dpi fonts must be placed in
7780 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7784 Character-cell fonts, cursor fonts, and other
7785 low-resolution fonts must be placed in
7786 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7792 Speedo fonts must be placed in
7793 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7797 Type 1 fonts must be placed in
7798 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7799 metric files are available, they must be placed here
7804 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7805 other than those listed above must be neither
7806 created nor used. (The <file>PEX</file>, <file>CID</file>,
7807 and <file>cyrillic</file> directories are excepted for
7808 historical reasons, but installation of files into
7809 these directories remains discouraged.)
7813 Font packages may, instead of placing files directly
7814 in the X font directories listed above, provide
7815 symbolic links in that font directory pointing to
7816 the files' actual location in the filesystem. Such
7817 a location must comply with the FHS.
7821 Font packages should not contain both 75dpi and
7822 100dpi versions of a font. If both are available,
7823 they should be provided in separate binary packages
7824 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7825 the names of the packages containing the
7826 corresponding fonts.
7830 Fonts destined for the <file>misc</file> subdirectory
7831 should not be included in the same package as 75dpi
7832 or 100dpi fonts; instead, they should be provided in
7833 a separate package with <tt>-misc</tt> appended to
7838 Font packages must not provide the files
7839 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7840 <file>fonts.scale</file> in a font directory:
7843 <file>fonts.dir</file> files must not be provided at all.
7847 <file>fonts.alias</file> and <file>fonts.scale</file>
7848 files, if needed, should be provided in the
7850 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7851 where <var>fontdir</var> is the name of the
7853 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7854 package's corresponding fonts are stored
7855 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7856 <var>package</var> is the name of the package
7857 that provides these fonts, and
7858 <var>extension</var> is either <tt>scale</tt>
7859 or <tt>alias</tt>, whichever corresponds to
7866 Font packages must declare a dependency on
7867 <tt>xutils (>> 4.0.3)</tt> in their control
7872 Font packages that provide one or more
7873 <file>fonts.scale</file> files as described above must
7874 invoke <prgn>update-fonts-scale</prgn> on each
7875 directory into which they installed fonts
7876 <em>before</em> invoking
7877 <prgn>update-fonts-dir</prgn> on that directory.
7878 This invocation must occur in both the
7879 <prgn>postinst</prgn> (for all arguments) and
7880 <prgn>postrm</prgn> (for all arguments except
7881 <tt>upgrade</tt>) scripts.
7885 Font packages that provide one or more
7886 <file>fonts.alias</file> files as described above must
7887 invoke <prgn>update-fonts-alias</prgn> on each
7888 directory into which they installed fonts. This
7889 invocation must occur in both the
7890 <prgn>postinst</prgn> (for all arguments) and
7891 <prgn>postrm</prgn> (for all arguments except
7892 <tt>upgrade</tt>) scripts.
7896 Font packages must invoke
7897 <prgn>update-fonts-dir</prgn> on each directory into
7898 which they installed fonts. This invocation must
7899 occur in both the <prgn>postinst</prgn> (for all
7900 arguments) and <prgn>postrm</prgn> (for all
7901 arguments except <tt>upgrade</tt>) scripts.
7905 Font packages must not provide alias names for the
7906 fonts they include which collide with alias names
7907 already in use by fonts already packaged.
7911 Font packages must not provide fonts with the same
7912 XLFD registry name as another font already packaged.
7919 <heading>Application defaults files</heading>
7922 Application defaults files must be installed in the
7923 directory <file>/etc/X11/app-defaults/</file> (use of a
7924 localized subdirectory of <file>/etc/X11/</file> as described
7925 in the <em>X Toolkit Intrinsics - C Language
7926 Interface</em> manual is also permitted). They must be
7927 registered as <tt>conffile</tt>s or handled as
7928 configuration files. Packages must not provide the
7929 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7933 Customization of programs' X resources may also be
7934 supported with the provision of a file with the same name
7935 as that of the package placed in the
7936 <file>/etc/X11/Xresources/</file> directory, which must
7937 registered as a <tt>conffile</tt> or handled as a
7938 configuration file.<footnote>
7939 Note that this mechanism is not the same as using
7940 app-defaults; app-defaults are tied to the client
7941 binary on the local filesystem, whereas X resources
7942 are stored in the X server and affect all connecting
7945 <em>Important:</em> packages that install files into the
7946 <file>/etc/X11/Xresources/</file> directory must conflict with
7947 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7948 it is possible for the installing package to destroy a
7949 previously-existing <file>/etc/X11/Xresources</file> file
7950 which had been customized by the system administrator.
7955 <heading>Installation directory issues</heading>
7958 Packages using the X Window System should not be
7959 configured to install files under the <file>/usr/X11R6/</file>
7960 directory unless they use <prgn>imake</prgn>. The
7961 <file>/usr/X11R6/</file> directory hierarchy should be
7962 regarded as deprecated for all packages except the X
7963 Window System itself, and those which use the
7964 <prgn>imake</prgn> program it provides, in which case the
7965 packages may transition out of the <file>/usr/X11R6/</file>
7966 directory at the maintainer's discretion.<footnote>
7967 <prgn>Imake</prgn>-using programs are exempt because,
7968 as long as they are written correctly, the pathnames
7969 they use to locate resources and install themselves
7970 are derived wholly from the X Window System
7971 configuration. Thus, in the event that the X Window
7972 System moves to <file>/usr/X11R7/</file>,
7973 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7974 that is required for these programs is a recompile
7975 against the corresponding X Window System library
7976 development packages.
7981 Programs that use GNU <prgn>autoconf</prgn> and
7982 <prgn>automake</prgn> are usually easily configured at
7983 compile time to use <file>/usr/</file> instead of
7984 <file>/usr/X11R6/</file>, and this should be done whenever
7985 possible. Configuration files for window managers and
7986 display managers should be placed in a subdirectory of
7987 <file>/etc/X11/</file> corresponding to the package name due
7988 to these programs' tight integration with the mechanisms
7989 of the X Window System. Application-level programs should
7990 use the <file>/etc/</file> directory unless otherwise mandated
7995 The installation of files into subdirectories
7996 of <file>/usr/X11R6/include/X11/</file> and
7997 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7998 package maintainers should determine if subdirectories of
7999 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8000 instead. (The use of symbolic links from the
8001 <file>X11R6</file> directories to other FHS-compliant
8002 locations is encouraged if the program is not easily
8003 configured to look elsewhere for its files.)
8007 Packages must not provide or install files into the directories
8008 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8009 <file>/usr/lib/X11/</file>. Files within a package should,
8010 however, make reference to these directories, rather than
8011 their <tt>X11R6</tt>-named counterparts
8012 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8013 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8014 referred to have not been moved to other FHS-compliant
8020 <heading>The OSF/Motif and OpenMotif libraries</heading>
8023 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8024 OpenMotif libraries</em><footnote>
8025 OSF/Motif and OpenMotif are collectively referred to as
8026 "Motif" in this policy document.
8028 should be compiled against and tested with LessTif (a free
8029 re-implementation of Motif) instead. If the maintainer
8030 judges that the program or programs do not work
8031 sufficiently well with LessTif to be distributed and
8032 supported, but do so when compiled against Motif, then two
8033 versions of the package should be created; one linked
8034 statically against Motif and with <tt>-smotif</tt>
8035 appended to the package name, and one linked dynamically
8036 against Motif and with <tt>-dmotif</tt> appended to the
8041 Both Motif-linked versions are dependent
8042 upon non-DFSG-compliant software and thus cannot be
8043 uploaded to the <em>main</em> distribution; if the
8044 software is itself DFSG-compliant it may be uploaded to
8045 the <em>contrib</em> distribution. While known existing
8046 versions of Motif permit unlimited redistribution of
8047 binaries linked against the library (whether statically or
8048 dynamically), it is the package maintainer's
8049 responsibility to determine whether this is permitted by
8050 the license of the copy of Motif in his or her possession.
8056 <heading>Perl programs and modules</heading>
8059 Perl programs and modules should follow the current Perl policy.
8063 The Perl policy can be found in the <tt>perl-policy</tt>
8064 files in the <tt>debian-policy</tt> package.
8065 It is also available from the Debian web mirrors at
8066 <tt><url name="/doc/packaging-manuals/perl-policy/"
8067 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8072 <heading>Emacs lisp programs</heading>
8075 Please refer to the "Debian Emacs Policy" for details of how to
8076 package emacs lisp programs.
8080 The Emacs policy is available in
8081 <file>debian-emacs-policy.gz</file> of the
8082 <package>emacsen-common</package> package.
8083 It is also available from the Debian web mirrors at
8084 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8085 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8090 <heading>Games</heading>
8093 The permissions on <file>/var/games</file> are mode 755, owner
8094 <tt>root</tt> and group <tt>root</tt>.
8098 Each game decides on its own security policy.</p>
8101 Games which require protected, privileged access to
8102 high-score files, savegames, etc., may be made
8103 set-<em>group</em>-id (mode 2755) and owned by
8104 <tt>root.games</tt>, and use files and directories with
8105 appropriate permissions (770 <tt>root.games</tt>, for
8106 example). They must not be made
8107 set-<em>user</em>-id, as this causes security problems. (If
8108 an attacker can subvert any set-user-id game they can
8109 overwrite the executable of any other, causing other players
8110 of these games to run a Trojan horse program. With a
8111 set-group-id game the attacker only gets access to less
8112 important game data, and if they can get at the other
8113 players' accounts at all it will take considerably more
8117 Some packages, for example some fortune cookie programs, are
8118 configured by the upstream authors to install with their
8119 data files or other static information made unreadable so
8120 that they can only be accessed through set-id programs
8121 provided. You should not do this in a Debian package: anyone can
8122 download the <file>.deb</file> file and read the data from it,
8123 so there is no point making the files unreadable. Not
8124 making the files unreadable also means that you don't have
8125 to make so many programs set-id, which reduces the risk of a
8129 As described in the FHS, binaries of games should be
8130 installed in the directory <file>/usr/games</file>. This also
8131 applies to games that use the X Window System. Manual pages
8132 for games (X and non-X games) should be installed in
8133 <file>/usr/share/man/man6</file>.</p>
8139 <heading>Documentation</heading>
8142 <heading>Manual pages</heading>
8145 You should install manual pages in <prgn>nroff</prgn> source
8146 form, in appropriate places under <file>/usr/share/man</file>.
8147 You should only use sections 1 to 9 (see the FHS for more
8148 details). You must not install a preformatted "cat page".
8152 Each program, utility, and function should have an
8153 associated manual page included in the same package. It is
8154 suggested that all configuration files also have a manual
8155 page included as well. Manual pages for protocols and other
8156 auxiliary things are optional.
8160 If no manual page is available, this is considered as a bug
8161 and should be reported to the Debian Bug Tracking System (the
8162 maintainer of the package is allowed to write this bug report
8163 themselves, if they so desire). Do not close the bug report
8164 until a proper man page is available.<footnote>
8165 It is not very hard to write a man page. See the
8166 <url id="http://www.schweikhardt.net/man_page_howto.html"
8167 name="Man-Page-HOWTO">,
8168 <manref name="man" section="7">, the examples
8169 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8170 the helper programs <prgn>help2man</prgn>, or the
8171 directory <file>/usr/share/doc/man-db/examples</file>.
8176 You may forward a complaint about a missing man page to the
8177 upstream authors, and mark the bug as forwarded in the
8178 Debian bug tracking system. Even though the GNU Project do
8179 not in general consider the lack of a man page to be a bug,
8180 we do; if they tell you that they don't consider it a bug
8181 you should leave the bug in our bug tracking system open
8186 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8190 If one man page needs to be accessible via several names it
8191 is better to use a symbolic link than the <file>.so</file>
8192 feature, but there is no need to fiddle with the relevant
8193 parts of the upstream source to change from <file>.so</file> to
8194 symlinks: don't do it unless it's easy. You should not
8195 create hard links in the manual page directories, nor put
8196 absolute filenames in <file>.so</file> directives. The filename
8197 in a <file>.so</file> in a man page should be relative to the
8198 base of the man page tree (usually
8199 <file>/usr/share/man</file>). If you do not create any links
8200 (whether symlinks, hard links, or <tt>.so</tt> directives)
8201 in the filesystem to the alternate names of the man page,
8202 then you should not rely on <prgn>man</prgn> finding your
8203 man page under those names based solely on the information in
8204 the man page's header.<footnote>
8205 Supporting this in <prgn>man</prgn> often requires
8206 unreasonable processing time to find a manual page or to
8207 report that none exists, and moves knowledge into man's
8208 database that would be better left in the filesystem.
8209 This support is therefore deprecated and will cease to
8210 be present in the future.
8216 <heading>Info documents</heading>
8219 Info documents should be installed in <file>/usr/share/info</file>.
8220 They should be compressed with <tt>gzip -9</tt>.
8224 Your package should call <prgn>install-info</prgn> to update
8225 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8226 script when called with a <tt>configure</tt> argument, for
8228 <example compact="compact">
8229 install-info --quiet --section Development Development \
8230 /usr/share/info/foobar.info
8234 It is a good idea to specify a section for the location of
8235 your program; this is done with the <tt>--section</tt>
8236 switch. To determine which section to use, you should look
8237 at <file>/usr/share/info/dir</file> on your system and choose the most
8238 relevant (or create a new section if none of the current
8239 sections are relevant). Note that the <tt>--section</tt>
8240 flag takes two arguments; the first is a regular expression
8241 to match (case-insensitively) against an existing section,
8242 the second is used when creating a new one.</p>
8245 You should remove the entries in the <prgn>prerm</prgn>
8246 script when called with a <tt>remove</tt> argument:
8247 <example compact="compact">
8248 install-info --quiet --remove /usr/share/info/foobar.info
8252 If <prgn>install-info</prgn> cannot find a description entry
8253 in the Info file you must supply one. See <manref
8254 name="install-info" section="8"> for details.</p>
8258 <heading>Additional documentation</heading>
8261 Any additional documentation that comes with the package may
8262 be installed at the discretion of the package maintainer.
8263 Text documentation should be installed in the directory
8264 <file>/usr/share/doc/<var>package</var></file>, where
8265 <var>package</var> is the name of the package, and
8266 compressed with <tt>gzip -9</tt> unless it is small.
8270 If a package comes with large amounts of documentation which
8271 many users of the package will not require you should create
8272 a separate binary package to contain it, so that it does not
8273 take up disk space on the machines of users who do not need
8274 or want it installed.</p>
8277 It is often a good idea to put text information files
8278 (<file>README</file>s, changelogs, and so forth) that come with
8279 the source package in <file>/usr/share/doc/<var>package</var></file>
8280 in the binary package. However, you don't need to install
8281 the instructions for building and installing the package, of
8285 Packages must not require the existence of any files in
8286 <file>/usr/share/doc/</file> in order to function
8288 The system administrator should be able to
8289 delete files in <file>/usr/share/doc/</file> without causing
8290 any programs to break.
8292 Any files that are referenced by programs but are also
8293 useful as standalone documentation should be installed under
8294 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8295 <file>/usr/share/doc/<var>package</var></file>.
8299 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8300 link to another directory in <file>/usr/share/doc</file> only if
8301 the two packages both come from the same source and the
8302 first package Depends on the second.
8306 Former Debian releases placed all additional documentation
8307 in <file>/usr/doc/<var>package</var></file>. This has been
8308 changed to <file>/usr/share/doc/<var>package</var></file>,
8309 and packages must not put documentation in the directory
8310 <file>/usr/doc/<var>package</var></file>. <footnote>
8311 At this phase of the transition, we no longer require a
8312 symbolic link in <file>/usr/doc/</file>. At a later point,
8313 policy shall change to make the symbolic links a bug.
8319 <heading>Preferred documentation formats</heading>
8322 The unification of Debian documentation is being carried out
8326 If your package comes with extensive documentation in a
8327 markup format that can be converted to various other formats
8328 you should if possible ship HTML versions in a binary
8329 package, in the directory
8330 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8331 its subdirectories.<footnote>
8332 The rationale: The important thing here is that HTML
8333 docs should be available in <em>some</em> package, not
8334 necessarily in the main binary package.
8339 Other formats such as PostScript may be provided at the
8340 package maintainer's discretion.
8344 <sect id="copyrightfile">
8345 <heading>Copyright information</heading>
8348 Every package must be accompanied by a verbatim copy of its
8349 copyright and distribution license in the file
8350 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8351 file must neither be compressed nor be a symbolic link.
8355 In addition, the copyright file must say where the upstream
8356 sources (if any) were obtained. It should name the original
8357 authors of the package and the Debian maintainer(s) who were
8358 involved with its creation.</p>
8361 A copy of the file which will be installed in
8362 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8363 be in <file>debian/copyright</file> in the source package.
8367 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8368 link to another directory in <file>/usr/share/doc</file> only if
8369 the two packages both come from the same source and the
8370 first package Depends on the second. These rules are
8371 important because copyrights must be extractable by
8376 Packages distributed under the UCB BSD license, the Artistic
8377 license, the GNU GPL, and the GNU LGPL should refer to the
8378 files <file>/usr/share/common-licenses/BSD</file>,
8379 <file>/usr/share/common-licenses/Artistic</file>,
8380 <file>/usr/share/common-licenses/GPL</file>, and
8381 <file>/usr/share/common-licenses/LGPL</file> respectively,
8382 rather than quoting them in the copyright file.
8386 You should not use the copyright file as a general <file>README</file>
8387 file. If your package has such a file it should be
8388 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8389 <file>README.Debian</file> or some other appropriate place.</p>
8393 <heading>Examples</heading>
8396 Any examples (configurations, source files, whatever),
8397 should be installed in a directory
8398 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8399 files should not be referenced by any program: they're there
8400 for the benefit of the system administrator and users as
8401 documentation only. Architecture-specific example files
8402 should be installed in a directory
8403 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8405 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8406 latter directory itself may be a symbolic link to the
8411 If the purpose of a package is to provide examples, then the
8412 example files may be installed into
8413 <file>/usr/share/doc/<var>package</var></file>.
8417 <sect id="changelogs">
8418 <heading>Changelog files</heading>
8421 Packages that are not Debian-native must contain a
8422 compressed copy of the <file>debian/changelog</file> file from
8423 the Debian source tree in
8424 <file>/usr/share/doc/<var>package</var></file> with the name
8425 <file>changelog.Debian.gz</file>.
8429 If an upstream changelog is available, it should be accessible as
8430 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8431 plain text. If the upstream changelog is distributed in
8432 HTML, it should be made available in that form as
8433 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8434 and a plain text <file>changelog.gz</file> should be generated
8435 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8436 the upstream changelog files do not already conform to this
8437 naming convention, then this may be achieved either by
8438 renaming the files, or by adding a symbolic link, at the
8439 maintainer's discretion.<footnote>
8440 Rationale: People should not have to look in places for
8441 upstream changelogs merely because they are given
8442 different names or are distributed in HTML format.
8447 All of these files should be installed compressed using
8448 <tt>gzip -9</tt>, as they will become large with time even
8449 if they start out small.
8453 If the package has only one changelog which is used both as
8454 the Debian changelog and the upstream one because there is
8455 no separate upstream maintainer then that changelog should
8456 usually be installed as
8457 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8458 there is a separate upstream maintainer, but no upstream
8459 changelog, then the Debian changelog should still be called
8460 <file>changelog.Debian.gz</file>.
8464 For details about the format and contents of the Debian
8465 changelog file, please see <ref id="dpkgchangelog">.
8470 <appendix id="pkg-scope">
8471 <heading>Introduction and scope of these appendices</heading>
8474 These appendices are taken essentially verbatim from the
8475 now-deprecated Packaging Manual, version 3.2.1.0. They are
8476 the chapters which are likely to be of use to package
8477 maintainers and which have not already been included in the
8478 policy document itself. Most of these sections are very likely
8479 not relevant to policy; they should be treated as
8480 documentation for the packaging system. Please note that these
8481 appendices are included for convenience, and for historical
8482 reasons: they used to be part of policy package, and they have
8483 not yet been incorporated into dpkg documentation. However,
8484 they still have value, and hence they are presented here.
8488 They have not yet been checked to ensure that they are
8489 compatible with the contents of policy, and if there are any
8490 contradictions, the version in the main policy document takes
8491 precedence. The remaining chapters of the old Packaging
8492 Manual have also not been read in detail to ensure that there
8493 are not parts which have been left out. Both of these will be
8498 Certain parts of the Packaging manual were integrated into the
8499 Policy Manual proper, and removed from the appendices. Links
8500 have been placed from the old locations to the new ones.
8504 <prgn>dpkg</prgn> is a suite of programs for creating binary
8505 package files and installing and removing them on Unix
8507 <prgn>dpkg</prgn> is targetted primarily at Debian
8508 GNU/Linux, but may work on or be ported to other
8514 The binary packages are designed for the management of
8515 installed executable programs (usually compiled binaries) and
8516 their associated data, though source code examples and
8517 documentation are provided as part of some packages.</p>
8520 This manual describes the technical aspects of creating Debian
8521 binary packages (<file>.deb</file> files). It documents the
8522 behaviour of the package management programs
8523 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8524 they interact with packages.</p>
8527 It also documents the interaction between
8528 <prgn>dselect</prgn>'s core and the access method scripts it
8529 uses to actually install the selected packages, and describes
8530 how to create a new access method.</p>
8533 This manual does not go into detail about the options and
8534 usage of the package building and installation tools. It
8535 should therefore be read in conjuction with those programs'
8540 The utility programs which are provided with <prgn>dpkg</prgn>
8541 for managing various system configuration and similar issues,
8542 such as <prgn>update-rc.d</prgn> and
8543 <prgn>install-info</prgn>, are not described in detail here -
8544 please see their man pages.
8548 It is assumed that the reader is reasonably familiar with the
8549 <prgn>dpkg</prgn> System Administrators' manual.
8550 Unfortunately this manual does not yet exist.
8554 The Debian version of the FSF's GNU hello program is provided
8555 as an example for people wishing to create Debian
8556 packages. The Debian <prgn>debmake</prgn> package is
8557 recommended as a very helpful tool in creating and maintaining
8558 Debian packages. However, while the tools and examples are
8559 helpful, they do not replace the need to read and follow the
8560 Policy and Programmer's Manual.</p>
8563 <appendix id="pkg-binarypkg">
8564 <heading>Binary packages (from old Packaging Manual)</heading>
8567 The binary package has two main sections. The first part
8568 consists of various control information files and scripts used
8569 by <prgn>dpkg</prgn> when installing and removing. See <ref
8570 id="pkg-controlarea">.
8574 The second part is an archive containing the files and
8575 directories to be installed.
8579 In the future binary packages may also contain other
8580 components, such as checksums and digital signatures. The
8581 format for the archive is described in full in the
8582 <file>deb(5)</file> man page.
8586 <sect id="pkg-bincreating"><heading>Creating package files -
8587 <prgn>dpkg-deb</prgn>
8591 All manipulation of binary package files is done by
8592 <prgn>dpkg-deb</prgn>; it's the only program that has
8593 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8594 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8595 will spot that the options requested are appropriate to
8596 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8601 In order to create a binary package you must make a
8602 directory tree which contains all the files and directories
8603 you want to have in the filesystem data part of the package.
8604 In Debian-format source packages this directory is usually
8605 <file>debian/tmp</file>, relative to the top of the package's
8610 They should have the locations (relative to the root of the
8611 directory tree you're constructing) ownerships and
8612 permissions which you want them to have on the system when
8617 With current versions of <prgn>dpkg</prgn> the uid/username
8618 and gid/groupname mappings for the users and groups being
8619 used should be the same on the system where the package is
8620 built and the one where it is installed.
8624 You need to add one special directory to the root of the
8625 miniature filesystem tree you're creating:
8626 <prgn>DEBIAN</prgn>. It should contain the control
8627 information files, notably the binary package control file
8628 (see <ref id="pkg-controlfile">).
8632 The <prgn>DEBIAN</prgn> directory will not appear in the
8633 filesystem archive of the package, and so won't be installed
8634 by <prgn>dpkg</prgn> when the package is installed.
8638 When you've prepared the package, you should invoke:
8640 dpkg --build <var>directory</var>
8645 This will build the package in
8646 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8647 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8648 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8653 See the man page <manref name="dpkg-deb" section="8"> for details of how
8654 to examine the contents of this newly-created file. You may find the
8655 output of following commands enlightening:
8657 dpkg-deb --info <var>filename</var>.deb
8658 dpkg-deb --contents <var>filename</var>.deb
8659 dpkg --contents <var>filename</var>.deb
8661 To view the copyright file for a package you could use this command:
8663 dpkg --fsys-tarfile <var>filename</var>.deb | tar xO ./usr/share/doc/\*/copyright | pager
8668 <sect id="pkg-controlarea">
8669 <heading>Package control information files</heading>
8672 The control information portion of a binary package is a
8673 collection of files with names known to <prgn>dpkg</prgn>.
8674 It will treat the contents of these files specially - some
8675 of them contain information used by <prgn>dpkg</prgn> when
8676 installing or removing the package; others are scripts which
8677 the package maintainer wants <prgn>dpkg</prgn> to run.
8681 It is possible to put other files in the package control
8682 area, but this is not generally a good idea (though they
8683 will largely be ignored).
8687 Here is a brief list of the control info files supported by
8688 <prgn>dpkg</prgn> and a summary of what they're used for.
8693 <tag><tt>control</tt>
8696 This is the key description file used by
8697 <prgn>dpkg</prgn>. It specifies the package's name
8698 and version, gives its description for the user,
8699 states its relationships with other packages, and so
8700 forth. See <ref id="sourcecontrolfiles"> and
8701 <ref id="binarycontrolfiles">.
8705 It is usually generated automatically from information
8706 in the source package by the
8707 <prgn>dpkg-gencontrol</prgn> program, and with
8708 assistance from <prgn>dpkg-shlibdeps</prgn>.
8709 See <ref id="pkg-sourcetools">.
8713 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8718 These are exectuable files (usually scripts) which
8719 <prgn>dpkg</prgn> runs during installation, upgrade
8720 and removal of packages. They allow the package to
8721 deal with matters which are particular to that package
8722 or require more complicated processing than that
8723 provided by <prgn>dpkg</prgn>. Details of when and
8724 how they are called are in <ref id="maintainerscripts">.
8728 It is very important to make these scripts idempotent.
8729 See <ref id="idempotency">.
8733 The maintainer scripts are guaranteed to run with a
8734 controlling terminal and can interact with the user.
8735 See <ref id="controllingterminal">.
8739 <tag><tt>conffiles</tt>
8742 This file contains a list of configuration files which
8743 are to be handled automatically by <prgn>dpkg</prgn>
8744 (see <ref id="pkg-conffiles">). Note that not necessarily
8745 every configuration file should be listed here.
8748 <tag><tt>shlibs</tt>
8751 This file contains a list of the shared libraries
8752 supplied by the package, with dependency details for
8753 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8754 when it determines what dependencies are required in a
8755 package control file. The <tt>shlibs</tt> file format
8756 is described on <ref id="shlibs">.
8761 <sect id="pkg-controlfile">
8762 <heading>The main control information file: <tt>control</tt></heading>
8765 The most important control information file used by
8766 <prgn>dpkg</prgn> when it installs a package is
8767 <tt>control</tt>. It contains all the package's "vital
8772 The binary package control files of packages built from
8773 Debian sources are made by a special tool,
8774 <prgn>dpkg-gencontrol</prgn>, which reads
8775 <file>debian/control</file> and <file>debian/changelog</file> to
8776 find the information it needs. See <ref id="pkg-sourcepkg"> for
8781 The fields in binary package control files are listed in
8782 <ref id="binarycontrolfiles">.
8786 A description of the syntax of control files and the purpose
8787 of the fields is available in <ref id="controlfields">.
8792 <heading>Time Stamps</heading>
8795 See <ref id="timestamps">.
8800 <appendix id="pkg-sourcepkg">
8801 <heading>Source packages (from old Packaging Manual) </heading>
8804 The Debian binary packages in the distribution are generated
8805 from Debian sources, which are in a special format to assist
8806 the easy and automatic building of binaries.
8809 <sect id="pkg-sourcetools">
8810 <heading>Tools for processing source packages</heading>
8813 Various tools are provided for manipulating source packages;
8814 they pack and unpack sources and help build of binary
8815 packages and help manage the distribution of new versions.
8819 They are introduced and typical uses described here; see
8820 <manref name="dpkg-source" section="1"> for full
8821 documentation about their arguments and operation.
8825 For examples of how to construct a Debian source package,
8826 and how to use those utilities that are used by Debian
8827 source packages, please see the <prgn>hello</prgn> example
8831 <sect1 id="pkg-dpkg-source">
8833 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8838 This program is frequently used by hand, and is also
8839 called from package-independent automated building scripts
8840 such as <prgn>dpkg-buildpackage</prgn>.
8844 To unpack a package it is typically invoked with
8846 dpkg-source -x <var>.../path/to/filename</var>.dsc
8851 with the <file><var>filename</var>.tar.gz</file> and
8852 <file><var>filename</var>.diff.gz</file> (if applicable) in
8853 the same directory. It unpacks into
8854 <file><var>package</var>-<var>version</var></file>, and if
8856 <file><var>package</var>-<var>version</var>.orig</file>, in
8857 the current directory.
8861 To create a packed source archive it is typically invoked:
8863 dpkg-source -b <var>package</var>-<var>version</var>
8868 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8869 <file>.diff.gz</file> (if appropriate) in the current
8870 directory. <prgn>dpkg-source</prgn> does not clean the
8871 source tree first - this must be done separately if it is
8876 See also <ref id="pkg-sourcearchives">.</p>
8880 <sect1 id="pkg-dpkg-buildpackage">
8882 <prgn>dpkg-buildpackage</prgn> - overall package-building
8887 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8888 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8889 targets <tt>clean</tt>, <tt>build</tt> and
8890 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8891 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8892 source and binary package upload.
8896 It is usually invoked by hand from the top level of the
8897 built or unbuilt source directory. It may be invoked with
8898 no arguments; useful arguments include:
8899 <taglist compact="compact">
8900 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8903 Do not sign the <tt>.changes</tt> file or the
8904 source package <tt>.dsc</tt> file, respectively.</p>
8906 <tag><tt>-p<var>sign-command</var></tt></tag>
8909 Invoke <var>sign-command</var> instead of finding
8910 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8911 <var>sign-command</var> must behave just like
8912 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
8914 <tag><tt>-r<var>root-command</var></tt></tag>
8917 When root privilege is required, invoke the command
8918 <var>root-command</var>. <var>root-command</var>
8919 should invoke its first argument as a command, from
8920 the <prgn>PATH</prgn> if necessary, and pass its
8921 second and subsequent arguments to the command it
8922 calls. If no <var>root-command</var> is supplied
8923 then <var>dpkg-buildpackage</var> will take no
8924 special action to gain root privilege, so that for
8925 most packages it will have to be invoked as root to
8928 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8931 Two types of binary-only build and upload - see
8932 <manref name="dpkg-source" section="1">.
8939 <sect1 id="pkg-dpkg-gencontrol">
8941 <prgn>dpkg-gencontrol</prgn> - generates binary package
8946 This program is usually called from <file>debian/rules</file>
8947 (see <ref id="pkg-sourcetree">) in the top level of the source
8952 This is usually done just before the files and directories in the
8953 temporary directory tree where the package is being built have their
8954 permissions and ownerships set and the package is constructed using
8955 <prgn>dpkg-deb/</prgn>
8957 This is so that the control file which is produced has
8958 the right permissions
8963 <prgn>dpkg-gencontrol</prgn> must be called after all the
8964 files which are to go into the package have been placed in
8965 the temporary build directory, so that its calculation of
8966 the installed size of a package is correct.
8970 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8971 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8972 variable substitutions created by
8973 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8978 For a package which generates only one binary package, and
8979 which builds it in <file>debian/tmp</file> relative to the top
8980 of the source package, it is usually sufficient to call
8981 <prgn>dpkg-gencontrol</prgn>.
8985 Sources which build several binaries will typically need
8988 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8989 </example> The <tt>-P</tt> tells
8990 <prgn>dpkg-gencontrol</prgn> that the package is being
8991 built in a non-default directory, and the <tt>-p</tt>
8992 tells it which package's control file should be generated.
8996 <prgn>dpkg-gencontrol</prgn> also adds information to the
8997 list of files in <file>debian/files</file>, for the benefit of
8998 (for example) a future invocation of
8999 <prgn>dpkg-genchanges</prgn>.</p>
9002 <sect1 id="pkg-dpkg-shlibdeps">
9004 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9009 This program is usually called from <file>debian/rules</file>
9010 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9011 id="pkg-sourcetree">), in the top level of the source tree.
9015 Its arguments are executables.
9018 In a forthcoming dpkg version,
9019 <prgn>dpkg-shlibdeps</prgn> would be required to be
9020 called on shared libraries as well.
9023 They may be specified either in the locations in the
9024 source tree where they are created or in the locations
9025 in the temporary build tree where they are installed
9026 prior to binary package creation.
9028 </footnote> for which shared library dependencies should
9029 be included in the binary package's control file.
9033 If some of the found shared libraries should only
9034 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9035 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9036 by using the <tt>-d<var>dependency-field</var></tt> option
9037 before those executable(s). (Each <tt>-d</tt> option
9038 takes effect until the next <tt>-d</tt>.)
9042 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9043 output control file to be modified. Instead by default it
9044 adds to the <file>debian/substvars</file> file variable
9045 settings like <tt>shlibs:Depends</tt>. These variable
9046 settings must be referenced in dependency fields in the
9047 appropriate per-binary-package sections of the source
9052 For example, a package that generates an essential part
9053 which requires dependencies, and optional parts that
9054 which only require a recommendation, would separate those
9055 two sets of dependencies into two different fields.<footnote>
9056 At the time of writing, an example for this was the
9057 <package/xmms/ package, with Depends used for the xmms
9058 executable, Recommends for the plug-ins and Suggests for
9059 even more optional features provided by unzip.
9061 It can say in its <file>debian/rules</file>:
9063 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9064 -dRecommends <var>optionalpart anotheroptionalpart</var>
9066 and then in its main control file <file>debian/control</file>:
9069 Depends: ${shlibs:Pre-Depends}
9070 Recommends: ${shlibs:Recommends}
9076 Sources which produce several binary packages with
9077 different shared library dependency requirements can use
9078 the <tt>-p<var>varnameprefix</var></tt> option to override
9079 the default <tt>shlibs:</tt> prefix (one invocation of
9080 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9081 They can thus produce several sets of dependency
9082 variables, each of the form
9083 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9084 which can be referred to in the appropriate parts of the
9085 binary package control files.
9090 <sect1 id="pkg-dpkg-distaddfile">
9092 <prgn>dpkg-distaddfile</prgn> - adds a file to
9093 <file>debian/files</file>
9097 Some packages' uploads need to include files other than
9098 the source and binary package files.
9102 <prgn>dpkg-distaddfile</prgn> adds a file to the
9103 <file>debian/files</file> file so that it will be included in
9104 the <file>.changes</file> file when
9105 <prgn>dpkg-genchanges</prgn> is run.
9109 It is usually invoked from the <tt>binary</tt> target of
9110 <file>debian/rules</file>:
9112 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9114 The <var>filename</var> is relative to the directory where
9115 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9116 is usually the directory above the top level of the source
9117 tree. The <file>debian/rules</file> target should put the
9118 file there just before or just after calling
9119 <prgn>dpkg-distaddfile</prgn>.
9123 The <var>section</var> and <var>priority</var> are passed
9124 unchanged into the resulting <file>.changes</file> file.
9129 <sect1 id="pkg-dpkg-genchanges">
9131 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9136 This program is usually called by package-independent
9137 automatic building scripts such as
9138 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9143 It is usually called in the top level of a built source
9144 tree, and when invoked with no arguments will print out a
9145 straightforward <file>.changes</file> file based on the
9146 information in the source package's changelog and control
9147 file and the binary and source packages which should have
9153 <sect1 id="pkg-dpkg-parsechangelog">
9155 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9156 representation of a changelog
9160 This program is used internally by
9161 <prgn>dpkg-source</prgn> et al. It may also occasionally
9162 be useful in <file>debian/rules</file> and elsewhere. It
9163 parses a changelog, <file>debian/changelog</file> by default,
9164 and prints a control-file format representation of the
9165 information in it to standard output.
9169 <sect1 id="pkg-dpkg-architecture">
9171 <prgn>dpkg-architecture</prgn> - information about the build and
9176 This program can be used manually, but is also invoked by
9177 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9178 to set environment or make variables which specify the build and
9179 host architecture for the package building process.
9184 <sect id="pkg-sourcetree">
9185 <heading>The Debianised source tree</heading>
9188 The source archive scheme described later is intended to
9189 allow a Debianised source tree with some associated control
9190 information to be reproduced and transported easily. The
9191 Debianised source tree is a version of the original program
9192 with certain files added for the benefit of the
9193 Debianisation process, and with any other changes required
9194 made to the rest of the source code and installation
9199 The extra files created for Debian are in the subdirectory
9200 <file>debian</file> of the top level of the Debianised source
9201 tree. They are described below.
9204 <sect1 id="pkg-debianrules">
9205 <heading><file>debian/rules</file> - the main building script</heading>
9208 See <ref id="debianrules">.
9213 <sect1 id="pkg-dpkgchangelog">
9214 <heading><file>debian/changelog</file></heading>
9217 See <ref id="dpkgchangelog">.
9221 It is recommended that the entire changelog be encoded in the
9222 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9224 <url id="http://www.unicode.org/"
9225 name="Unicode">.<footnote>
9227 Support for Unicode, and specifically UTF-8, is
9228 steadily increasing among popular applications in
9229 Debian. For example, in unstable, GNOME 2 has
9230 excellent support (almost level 2) in almost all its
9231 applications; the big remaining one is gnome-terminal,
9232 of which one requires development versions in order to
9233 support UTF-8 (available in Debian experimental now if
9234 you want to play). I think that by the time sarge is
9235 released, UTF-8 support will start to hit critical
9238 I think it is fairly obvious that we need to
9239 eventually transition to UTF-8 for our package
9240 infrastructure; it is really the only sane charset in
9241 an international environment. Now, we can't switch to
9242 using UTF-8 for package control fields and the like
9243 until dpkg has better support, but one thing we can
9244 start doing today is requesting that Debian changelogs
9245 are UTF-8 encoded. At some point in time, we can start
9246 requiring them to do so.
9249 Checking for non-UTF8 characters in a changelog is
9250 trivial. Dump the file through
9251 <example>iconv -f utf-8 -t ucs-4</example>
9252 discard the output, and check the return
9253 value. If there are any characters in the stream
9254 which are invalid UTF-8 sequences, iconv will exit
9255 with an error code; and this will be the case for the
9256 vast majority of other character sets.
9261 <sect2><heading>Defining alternative changelog formats
9265 It is possible to use a different format to the standard
9266 one, by providing a parser for the format you wish to
9271 In order to have <tt>dpkg-parsechangelog</tt> run your
9272 parser, you must include a line within the last 40 lines
9273 of your file matching the Perl regular expression:
9274 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9275 parentheses should be the name of the format. For
9276 example, you might say:
9278 @@@ changelog-format: joebloggs @@@
9280 Changelog format names are non-empty strings of alphanumerics.
9284 If such a line exists then <tt>dpkg-parsechangelog</tt>
9285 will look for the parser as
9286 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9288 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9289 it is an error for it not to find it, or for it not to
9290 be an executable program. The default changelog format
9291 is <tt>dpkg</tt>, and a parser for it is provided with
9292 the <tt>dpkg</tt> package.
9296 The parser will be invoked with the changelog open on
9297 standard input at the start of the file. It should read
9298 the file (it may seek if it wishes) to determine the
9299 information required and return the parsed information
9300 to standard output in the form of a series of control
9301 fields in the standard format. By default it should
9302 return information about only the most recent version in
9303 the changelog; it should accept a
9304 <tt>-v<var>version</var></tt> option to return changes
9305 information from all versions present <em>strictly
9306 after</em> <var>version</var>, and it should then be an
9307 error for <var>version</var> not to be present in the
9313 <list compact="compact">
9314 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9315 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9316 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9317 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9318 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9319 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9320 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9325 If several versions are being returned (due to the use
9326 of <tt>-v</tt>), the urgency value should be of the
9327 highest urgency code listed at the start of any of the
9328 versions requested followed by the concatenated
9329 (space-separated) comments from all the versions
9330 requested; the maintainer, version, distribution and
9331 date should always be from the most recent version.
9335 For the format of the <tt>Changes</tt> field see
9336 <ref id="f-Changes">.
9340 If the changelog format which is being parsed always or
9341 almost always leaves a blank line between individual
9342 change notes these blank lines should be stripped out,
9343 so as to make the resulting output compact.
9347 If the changelog format does not contain date or package
9348 name information this information should be omitted from
9349 the output. The parser should not attempt to synthesise
9350 it or find it from other sources.
9354 If the changelog does not have the expected format the
9355 parser should exit with a nonzero exit status, rather
9356 than trying to muddle through and possibly generating
9361 A changelog parser may not interact with the user at
9367 <sect1 id="pkg-srcsubstvars">
9368 <heading><file>debian/substvars</file> and variable substitutions</heading>
9371 See <ref id="substvars">.
9377 <heading><file>debian/files</file></heading>
9380 See <ref id="debianfiles">.
9384 <sect1><heading><file>debian/tmp</file>
9388 This is the canonical temporary location for the
9389 construction of binary packages by the <tt>binary</tt>
9390 target. The directory <file>tmp</file> serves as the root of
9391 the filesystem tree as it is being constructed (for
9392 example, by using the package's upstream makefiles install
9393 targets and redirecting the output there), and it also
9394 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9395 id="pkg-bincreating">.
9399 If several binary packages are generated from the same
9400 source tree it is usual to use several
9401 <file>debian/tmp<var>something</var></file> directories, for
9402 example <file>tmp-a</file> or <file>tmp-doc</file>.
9406 Whatever <file>tmp</file> directories are created and used by
9407 <tt>binary</tt> must of course be removed by the
9408 <tt>clean</tt> target.</p></sect1>
9412 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9416 As it exists on the FTP site, a Debian source package
9417 consists of three related files. You must have the right
9418 versions of all three to be able to use them.
9423 <tag>Debian source control file - <tt>.dsc</tt></tag>
9425 This file is a control file used by <prgn>dpkg-source</prgn>
9426 to extract a source package.
9427 See <ref id="debiansourcecontrolfiles">.
9431 Original source archive -
9433 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9439 This is a compressed (with <tt>gzip -9</tt>)
9440 <prgn>tar</prgn> file containing the source code from
9441 the upstream authors of the program.
9446 Debianisation diff -
9448 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9454 This is a unified context diff (<tt>diff -u</tt>)
9455 giving the changes which are required to turn the
9456 original source into the Debian source. These changes
9457 may only include editing and creating plain files.
9458 The permissions of files, the targets of symbolic
9459 links and the characteristics of special files or
9460 pipes may not be changed and no files may be removed
9465 All the directories in the diff must exist, except the
9466 <file>debian</file> subdirectory of the top of the source
9467 tree, which will be created by
9468 <prgn>dpkg-source</prgn> if necessary when unpacking.
9472 The <prgn>dpkg-source</prgn> program will
9473 automatically make the <file>debian/rules</file> file
9474 executable (see below).</p></item>
9479 If there is no original source code - for example, if the
9480 package is specially prepared for Debian or the Debian
9481 maintainer is the same as the upstream maintainer - the
9482 format is slightly different: then there is no diff, and the
9484 <file><var>package</var>_<var>version</var>.tar.gz</file>,
9485 and preferably contains a directory named
9486 <file><var>package</var>-<var>version</var></file>.
9491 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9494 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9495 Debian source package. However, if it is not available it
9496 is possible to unpack a Debian source archive as follows:
9497 <enumlist compact="compact">
9500 Untar the tarfile, which will create a <file>.orig</file>
9504 <p>Rename the <file>.orig</file> directory to
9505 <file><var>package</var>-<var>version</var></file>.</p>
9509 Create the subdirectory <file>debian</file> at the top of
9510 the source tree.</p>
9512 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9514 <item><p>Untar the tarfile again if you want a copy of the original
9515 source code alongside the Debianised version.</p>
9520 It is not possible to generate a valid Debian source archive
9521 without using <prgn>dpkg-source</prgn>. In particular,
9522 attempting to use <prgn>diff</prgn> directly to generate the
9523 <file>.diff.gz</file> file will not work.
9527 <heading>Restrictions on objects in source packages</heading>
9530 The source package may not contain any hard links
9532 This is not currently detected when building source
9533 packages, but only when extracting
9537 Hard links may be permitted at some point in the
9538 future, but would require a fair amount of
9540 </footnote>, device special files, sockets or setuid or
9543 Setgid directories are allowed.
9548 The source packaging tools manage the changes between the
9549 original and Debianised source using <prgn>diff</prgn> and
9550 <prgn>patch</prgn>. Turning the original source tree as
9551 included in the <file>.orig.tar.gz</file> into the debianised
9552 source must not involve any changes which cannot be
9553 handled by these tools. Problematic changes which cause
9554 <prgn>dpkg-source</prgn> to halt with an error when
9555 building the source package are:
9556 <list compact="compact">
9557 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9559 <item><p>Changing the targets of symbolic links.</p>
9561 <item><p>Creating directories, other than <file>debian</file>.</p>
9563 <item><p>Changes to the contents of binary files.</p></item>
9564 </list> Changes which cause <prgn>dpkg-source</prgn> to
9565 print a warning but continue anyway are:
9566 <list compact="compact">
9569 Removing files, directories or symlinks.
9571 Renaming a file is not treated specially - it is
9572 seen as the removal of the old file (which
9573 generates a warning, but is otherwise ignored),
9574 and the creation of the new one.
9580 Changed text files which are missing the usual final
9581 newline (either in the original or the modified
9586 Changes which are not represented, but which are not detected by
9587 <prgn>dpkg-source</prgn>, are:
9588 <list compact="compact">
9589 <item><p>Changing the permissions of files (other than
9590 <file>debian/rules</file>) and directories.</p></item>
9595 The <file>debian</file> directory and <file>debian/rules</file>
9596 are handled specially by <prgn>dpkg-source</prgn> - before
9597 applying the changes it will create the <file>debian</file>
9598 directory, and afterwards it will make
9599 <file>debian/rules</file> world-exectuable.
9605 <appendix id="pkg-controlfields">
9606 <heading>Control files and their fields (from old Packaging Manual)</heading>
9609 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9610 data in a common format, known as control files. Binary and
9611 source packages have control data as do the <file>.changes</file>
9612 files which control the installation of uploaded files, and
9613 <prgn>dpkg</prgn>'s internal databases are in a similar
9618 <heading>Syntax of control files</heading>
9621 See <ref id="controlsyntax">.
9625 It is important to note that there are several fields which
9626 are optional as far as <prgn>dpkg</prgn> and the related
9627 tools are concerned, but which must appear in every Debian
9628 package, or whose omission may cause problems.
9633 <heading>List of fields</heading>
9636 See <ref id="controlfieldslist">.
9640 This section now contains only the fields that didn't belong
9641 to the Policy manual.
9644 <sect1 id="pkg-f-Filename">
9645 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9648 These fields in <tt>Packages</tt> files give the
9649 filename(s) of (the parts of) a package in the
9650 distribution directories, relative to the root of the
9651 Debian hierarchy. If the package has been split into
9652 several parts the parts are all listed in order, separated
9657 <sect1 id="pkg-f-Size">
9658 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9661 These fields in <file>Packages</file> files give the size (in
9662 bytes, expressed in decimal) and MD5 checksum of the
9663 file(s) which make(s) up a binary package in the
9664 distribution. If the package is split into several parts
9665 the values for the parts are listed in order, separated by
9670 <sect1 id="pkg-f-Status">
9671 <heading><tt>Status</tt></heading>
9674 This field in <prgn>dpkg</prgn>'s status file records
9675 whether the user wants a package installed, removed or
9676 left alone, whether it is broken (requiring
9677 reinstallation) or not and what its current state on the
9678 system is. Each of these pieces of information is a
9683 <sect1 id="pkg-f-Config-Version">
9684 <heading><tt>Config-Version</tt></heading>
9687 If a package is not installed or not configured, this
9688 field in <prgn>dpkg</prgn>'s status file records the last
9689 version of the package which was successfully
9694 <sect1 id="pkg-f-Conffiles">
9695 <heading><tt>Conffiles</tt></heading>
9698 This field in <prgn>dpkg</prgn>'s status file contains
9699 information about the automatically-managed configuration
9700 files held by a package. This field should <em>not</em>
9701 appear anywhere in a package!
9706 <heading>Obsolete fields</heading>
9709 These are still recognised by <prgn>dpkg</prgn> but should
9710 not appear anywhere any more.
9712 <taglist compact="compact">
9714 <tag><tt>Revision</tt></tag>
9715 <tag><tt>Package-Revision</tt></tag>
9716 <tag><tt>Package_Revision</tt></tag>
9718 The Debian revision part of the package version was
9719 at one point in a separate control file field. This
9720 field went through several names.
9723 <tag><tt>Recommended</tt></tag>
9724 <item>Old name for <tt>Recommends</tt>.</item>
9726 <tag><tt>Optional</tt></tag>
9727 <item>Old name for <tt>Suggests</tt>.</item>
9729 <tag><tt>Class</tt></tag>
9730 <item>Old name for <tt>Priority</tt>.</item>
9739 <appendix id="pkg-conffiles">
9740 <heading>Configuration file handling (from old Packaging Manual)</heading>
9743 <prgn>dpkg</prgn> can do a certain amount of automatic
9744 handling of package configuration files.
9748 Whether this mechanism is appropriate depends on a number of
9749 factors, but basically there are two approaches to any
9750 particular configuration file.
9754 The easy method is to ship a best-effort configuration in the
9755 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9756 handle updates. If the user is unlikely to want to edit the
9757 file, but you need them to be able to without losing their
9758 changes, and a new package with a changed version of the file
9759 is only released infrequently, this is a good approach.
9763 The hard method is to build the configuration file from
9764 scratch in the <prgn>postinst</prgn> script, and to take the
9765 responsibility for fixing any mistakes made in earlier
9766 versions of the package automatically. This will be
9767 appropriate if the file is likely to need to be different on
9771 <sect><heading>Automatic handling of configuration files by
9776 A package may contain a control area file called
9777 <tt>conffiles</tt>. This file should be a list of filenames
9778 of configuration files needing automatic handling, separated
9779 by newlines. The filenames should be absolute pathnames,
9780 and the files referred to should actually exist in the
9785 When a package is upgraded <prgn>dpkg</prgn> will process
9786 the configuration files during the configuration stage,
9787 shortly before it runs the package's <prgn>postinst</prgn>
9792 For each file it checks to see whether the version of the
9793 file included in the package is the same as the one that was
9794 included in the last version of the package (the one that is
9795 being upgraded from); it also compares the version currently
9796 installed on the system with the one shipped with the last
9801 If neither the user nor the package maintainer has changed
9802 the file, it is left alone. If one or the other has changed
9803 their version, then the changed version is preferred - i.e.,
9804 if the user edits their file, but the package maintainer
9805 doesn't ship a different version, the user's changes will
9806 stay, silently, but if the maintainer ships a new version
9807 and the user hasn't edited it the new version will be
9808 installed (with an informative message). If both have
9809 changed their version the user is prompted about the problem
9810 and must resolve the differences themselves.
9814 The comparisons are done by calculating the MD5 message
9815 digests of the files, and storing the MD5 of the file as it
9816 was included in the most recent version of the package.
9820 When a package is installed for the first time
9821 <prgn>dpkg</prgn> will install the file that comes with it,
9822 unless that would mean overwriting a file already on the
9827 However, note that <prgn>dpkg</prgn> will <em>not</em>
9828 replace a conffile that was removed by the user (or by a
9829 script). This is necessary because with some programs a
9830 missing file produces an effect hard or impossible to
9831 achieve in another way, so that a missing file needs to be
9832 kept that way if the user did it.
9836 Note that a package should <em>not</em> modify a
9837 <prgn>dpkg</prgn>-handled conffile in its maintainer
9838 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9839 the user confusing and possibly dangerous options for
9840 conffile update when the package is upgraded.</p>
9843 <sect><heading>Fully-featured maintainer script configuration
9848 For files which contain site-specific information such as
9849 the hostname and networking details and so forth, it is
9850 better to create the file in the package's
9851 <prgn>postinst</prgn> script.
9855 This will typically involve examining the state of the rest
9856 of the system to determine values and other information, and
9857 may involve prompting the user for some information which
9858 can't be obtained some other way.
9862 When using this method there are a couple of important
9863 issues which should be considered:
9867 If you discover a bug in the program which generates the
9868 configuration file, or if the format of the file changes
9869 from one version to the next, you will have to arrange for
9870 the postinst script to do something sensible - usually this
9871 will mean editing the installed configuration file to remove
9872 the problem or change the syntax. You will have to do this
9873 very carefully, since the user may have changed the file,
9874 perhaps to fix the very problem that your script is trying
9875 to deal with - you will have to detect these situations and
9876 deal with them correctly.
9880 If you do go down this route it's probably a good idea to
9881 make the program that generates the configuration file(s) a
9882 separate program in <file>/usr/sbin</file>, by convention called
9883 <file><var>package</var>config</file> and then run that if
9884 appropriate from the post-installation script. The
9885 <tt><var>package</var>config</tt> program should not
9886 unquestioningly overwrite an existing configuration - if its
9887 mode of operation is geared towards setting up a package for
9888 the first time (rather than any arbitrary reconfiguration
9889 later) you should have it check whether the configuration
9890 already exists, and require a <tt>--force</tt> flag to
9891 overwrite it.</p></sect>
9894 <appendix id="pkg-alternatives"><heading>Alternative versions of
9895 an interface - <prgn>update-alternatives</prgn> (from old
9900 When several packages all provide different versions of the
9901 same program or file it is useful to have the system select a
9902 default, but to allow the system administrator to change it
9903 and have their decisions respected.
9907 For example, there are several versions of the <prgn>vi</prgn>
9908 editor, and there is no reason to prevent all of them from
9909 being installed at once, each under their own name
9910 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9911 Nevertheless it is desirable to have the name <tt>vi</tt>
9912 refer to something, at least by default.
9916 If all the packages involved cooperate, this can be done with
9917 <prgn>update-alternatives</prgn>.
9921 Each package provides its own version under its own name, and
9922 calls <prgn>update-alternatives</prgn> in its postinst to
9923 register its version (and again in its prerm to deregister
9928 See the man page <manref name="update-alternatives"
9929 section="8"> for details.
9933 If <prgn>update-alternatives</prgn> does not seem appropriate
9934 you may wish to consider using diversions instead.</p>
9937 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9938 package's version of a file (from old Packaging Manual)
9942 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9943 when it reinstalls the package it belongs to, and to have it
9944 put the file from the package somewhere else instead.
9948 This can be used locally to override a package's version of a
9949 file, or by one package to override another's version (or
9950 provide a wrapper for it).
9954 Before deciding to use a diversion, read <ref
9955 id="pkg-alternatives"> to see if you really want a diversion
9956 rather than several alternative versions of a program.
9960 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9961 and updated by a special program <prgn>dpkg-divert</prgn>.
9962 Please see <manref name="dpkg-divert" section="8"> for full
9963 details of its operation.
9967 When a package wishes to divert a file from another, it should
9968 call <prgn>dpkg-divert</prgn> in its preinst to add the
9969 diversion and rename the existing file. For example,
9970 supposing that a <prgn>smailwrapper</prgn> package wishes to
9971 install a wrapper around <file>/usr/sbin/smail</file>:
9973 if [ install = "$1" ]; then
9974 dpkg-divert --package smailwrapper --add --rename \
9975 --divert /usr/sbin/smail.real /usr/sbin/smail
9977 </example> Testing <tt>$1</tt> is necessary so that the script
9978 doesn't try to add the diversion again when
9979 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
9980 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
9981 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
9982 get installed as the true version.
9986 The postrm has to do the reverse:
9988 if [ remove = "$1" ]; then
9989 dpkg-divert --package smailwrapper --remove --rename \
9990 --divert /usr/sbin/smail.real /usr/sbin/smail
9996 Do not attempt to divert a file which is vitally important for
9997 the system's operation - when using <prgn>dpkg-divert</prgn>
9998 there is a time, after it has been diverted but before
9999 <prgn>dpkg</prgn> has installed the new version, when the file
10000 does not exist.</p>
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