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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package><url name="debian-policy" id="http://packages.debian.org/debian-policy"></package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>.
168 Also available from the same directory are several other
169 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
170 and <file>policy.ps.gz</file>.
174 The <package>debian-policy</package> package also includes the file
175 <file>upgrading-checklist.txt</file> which indicates policy
176 changes between versions of this document.
181 <heading>Authors and Maintainers</heading>
184 Originally called "Debian GNU/Linux Policy Manual", this
185 manual was initially written in 1996 by Ian Jackson.
186 It was revised on November 27th, 1996 by David A. Morris.
187 Christian Schwarz added new sections on March 15th, 1997,
188 and reworked/restructured it in April-July 1997.
189 Christoph Lameter contributed the "Web Standard".
190 Julian Gilbey largely restructured it in 2001.
194 Since September 1998, the responsibility for the contents of
195 this document lies on the <url name="debian-policy mailing list"
196 id="mailto:debian-policy@lists.debian.org">. Proposals
197 are discussed there and inserted into policy after a certain
198 consensus is established.
199 <!-- insert shameless policy-process plug here eventually -->
200 The actual editing is done by a group of maintainers that have
201 no editorial powers. These are the current maintainers:
204 <item>Julian Gilbey</item>
205 <item>Branden Robinson</item>
206 <item>Josip Rodin</item>
207 <item>Manoj Srivastava</item>
212 While the authors of this document have tried hard to avoid
213 typos and other errors, these do still occur. If you discover
214 an error in this manual or if you want to give any
215 comments, suggestions, or criticisms please send an email to
216 the Debian Policy List,
217 <email>debian-policy@lists.debian.org</email>, or submit a
218 bug report against the <tt>debian-policy</tt> package.
222 Please do not try to reach the individual authors or maintainers
223 of the Policy Manual regarding changes to the Policy.
228 <heading>Related documents</heading>
231 There are several other documents other than this Policy Manual
232 that are necessary to fully understand some Debian policies and
237 The external "sub-policy" documents are referred to in:
238 <list compact="compact">
239 <item><ref id="fhs"></item>
240 <item><ref id="virtual_pkg"></item>
241 <item><ref id="menus"></item>
242 <item><ref id="mime"></item>
243 <item><ref id="perl"></item>
244 <item><ref id="maintscriptprompt"></item>
245 <item><ref id="emacs"></item>
250 In addition to those, which carry the weight of policy, there
251 is the Debian Developer's Reference. This document describes
252 procedures and resources for Debian developers, but it is
253 <em>not</em> normative; rather, it includes things that don't
254 belong in the Policy, such as best practices for developers.
258 The Developer's Reference is available in the
259 <package>developers-reference</package> package.
260 It's also available from the Debian web mirrors at
261 <tt><url name="/doc/developers-reference/"
262 id="http://www.debian.org/doc/developers-reference/"></tt>.
270 <heading>The Debian Archive</heading>
273 The Debian GNU/Linux system is maintained and distributed as a
274 collection of <em>packages</em>. Since there are so many of
275 them (currently well over 6000), they are split into
276 <em>sections</em> and given <em>priorities</em> to simplify
277 the handling of them.
281 The effort of the Debian project is to build a free operating
282 system, but not every package we want to make accessible is
283 <em>free</em> in our sense (see the Debian Free Software
284 Guidelines, below), or may be imported/exported without
285 restrictions. Thus, the archive is split into the sections
286 based on their licenses and other restrictions.
290 The aims of this are:
292 <list compact="compact">
293 <item>to allow us to make as much software available as we can</item>
294 <item>to allow us to encourage everyone to write free software,
296 <item>to allow us to make it easy for people to produce
297 CD-ROMs of our system without violating any licenses,
298 import/export restrictions, or any other laws.</item>
303 The <em>main</em> and the <em>non-US/main</em> sections
304 together form the <em>Debian GNU/Linux distribution</em>.
308 Packages in the other sections are not considered to be part
309 of the Debian distribution, although we support their use and
310 provide infrastructure for them (such as our bug-tracking
311 system and mailing lists). This Debian Policy Manual applies
312 to these packages as well.
316 <heading>The Debian Free Software Guidelines</heading>
318 The Debian Free Software Guidelines (DFSG) form our
319 definition of "free software". These are:
321 <tag>Free Redistribution
324 The license of a Debian component may not restrict any
325 party from selling or giving away the software as a
326 component of an aggregate software distribution
327 containing programs from several different
328 sources. The license may not require a royalty or
329 other fee for such sale.
334 The program must include source code, and must allow
335 distribution in source code as well as compiled form.
340 The license must allow modifications and derived
341 works, and must allow them to be distributed under the
342 same terms as the license of the original software.
344 <tag>Integrity of The Author's Source Code
347 The license may restrict source-code from being
348 distributed in modified form <em>only</em> if the
349 license allows the distribution of "patch files"
350 with the source code for the purpose of modifying the
351 program at build time. The license must explicitly
352 permit distribution of software built from modified
353 source code. The license may require derived works to
354 carry a different name or version number from the
355 original software. (This is a compromise. The Debian
356 Project encourages all authors to not restrict any
357 files, source or binary, from being modified.)
359 <tag>No Discrimination Against Persons or Groups
362 The license must not discriminate against any person
365 <tag>No Discrimination Against Fields of Endeavor
368 The license must not restrict anyone from making use
369 of the program in a specific field of endeavor. For
370 example, it may not restrict the program from being
371 used in a business, or from being used for genetic
374 <tag>Distribution of License
377 The rights attached to the program must apply to all
378 to whom the program is redistributed without the need
379 for execution of an additional license by those
382 <tag>License Must Not Be Specific to Debian
385 The rights attached to the program must not depend on
386 the program's being part of a Debian system. If the
387 program is extracted from Debian and used or
388 distributed without Debian but otherwise within the
389 terms of the program's license, all parties to whom
390 the program is redistributed must have the same
391 rights as those that are granted in conjunction with
394 <tag>License Must Not Contaminate Other Software
397 The license must not place restrictions on other
398 software that is distributed along with the licensed
399 software. For example, the license must not insist
400 that all other programs distributed on the same medium
401 must be free software.
403 <tag>Example Licenses
406 The "GPL," "BSD," and "Artistic" licenses are examples of
407 licenses that we consider <em>free</em>.
414 <heading>Sections</heading>
417 <heading>The main section</heading>
420 Every package in <em>main</em> and <em>non-US/main</em>
421 must comply with the DFSG (Debian Free Software
426 In addition, the packages in <em>main</em>
427 <list compact="compact">
429 must not require a package outside of <em>main</em>
430 for compilation or execution (thus, the package must
431 not declare a "Depends", "Recommends", or
432 "Build-Depends" relationship on a non-<em>main</em>
436 must not be so buggy that we refuse to support them,
440 must meet all policy requirements presented in this
447 Similarly, the packages in <em>non-US/main</em>
448 <list compact="compact">
450 must not require a package outside of <em>main</em>
451 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
458 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
479 must not be so buggy that we refuse to support them,
483 must meet all policy requirements presented in this
490 Furthermore, packages in <em>contrib</em> must not require
491 a package in a <em>non-US</em> section for compilation or
496 Examples of packages which would be included in
497 <em>contrib</em> or <em>non-US/contrib</em> are:
498 <list compact="compact">
500 free packages which require <em>contrib</em>,
501 <em>non-free</em> packages or packages which are not
502 in our archive at all for compilation or execution,
506 wrapper packages or other sorts of free accessories for
513 <sect1 id="non-free">
514 <heading>The non-free section</heading>
517 Packages must be placed in <em>non-free</em> or
518 <em>non-US/non-free</em> if they are not compliant with
519 the DFSG or are encumbered by patents or other legal
520 issues that make their distribution problematic.
524 In addition, the packages in <em>non-free</em> and
525 <em>non-US/non-free</em>
526 <list compact="compact">
528 must not be so buggy that we refuse to support them,
532 must meet all policy requirements presented in this
533 manual that it is possible for them to meet.
535 It is possible that there are policy
536 requirements which the package is unable to
537 meet, for example, if the source is
538 unavailable. These situations will need to be
539 handled on a case-by-case basis.
547 <heading>The non-US sections</heading>
550 Non-free programs with cryptographic program code need to
551 be stored on the <em>non-us</em> server because of export
552 restrictions of the U.S.
556 Programs which use patented algorithms that have a
557 restricted license also need to be stored on "non-us",
558 since the non-us archive is located in a country where
559 patenting algorithms is not allowed.
563 A package depends on another package which is distributed
564 via the non-us server has to be stored on the non-us
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of
575 its copyright and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Subsections</heading>
653 The packages in the sections <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further
655 into <em>subsections</em> to simplify handling.
659 The section and subsection for each package should be
660 specified in the package's <tt>Section</tt> control
661 record (see <ref id="f-Section">).
662 However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
668 <em>subsection</em> if the package is in the
669 <em>main</em> section,
672 <em>section/subsection</em> if the package is in
673 the <em>contrib</em> or <em>non-free</em> section,
677 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
678 <tt>non-US/non-free</tt> if the package is in
679 <em>non-US/main</em>, <em>non-US/contrib</em> or
680 <em>non-US/non-free</em> respectively.
686 The Debian archive maintainers provide the authoritative
687 list of subsections. At present, they are:
688 <em>admin</em>, <em>base</em>, <em>comm</em>,
689 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
690 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
691 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
692 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
693 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
694 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
695 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
696 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
697 <em>science</em>, <em>shells</em>,
698 <em>sound</em>, <em>tex</em>, <em>text</em>,
699 <em>utils</em>, <em>web</em>, <em>x11</em>.
703 <sect id="priorities">
704 <heading>Priorities</heading>
707 Each package should have a <em>priority</em> value, which is
708 included in the package's <em>control record</em>
709 (see <ref id="f-Priority">).
710 This information is used by the Debian package management tools to
711 separate high-priority packages from less-important packages.
715 The following <em>priority levels</em> are recognised by the
716 Debian package management tools.
718 <tag><tt>required</tt></tag>
720 Packages which are necessary for the proper
721 functioning of the system (usually, this means that
722 dpkg functionality depends on these packages).
723 Removing an <tt>required</tt> package may cause your
724 system to become totally broken and you may not even
725 be able to use <prgn>dpkg</prgn> to put things back,
726 so only do so if you know what you are doing. Systems
727 with only the <tt>required</tt> packages are probably
728 unusable, but they do have enough functionality to
729 allow the sysadmin to boot and install more software.
731 <tag><tt>important</tt></tag>
733 Important programs, including those which one would
734 expect to find on any Unix-like system. If the
735 expectation is that an experienced Unix person who
736 found it missing would say "What on earth is going on,
737 where is <prgn>foo</prgn>?", it must be an
738 <tt>important</tt> package.<footnote>
739 This is an important criterion because we are
740 trying to produce, amongst other things, a free
743 Other packages without which the system will not run
744 well or be usable must also have priority
745 <tt>important</tt>. This does
746 <em>not</em> include Emacs, the X Window System, TeX
747 or any other large applications. The
748 <tt>important</tt> packages are just a bare minimum of
749 commonly-expected and necessary tools.
751 <tag><tt>standard</tt></tag>
753 These packages provide a reasonably small but not too
754 limited character-mode system. This is what will be
755 installed by default if the user doesn't select anything
756 else. It doesn't include many large applications.
758 <tag><tt>optional</tt></tag>
760 (In a sense everything that isn't required is
761 optional, but that's not what is meant here.) This is
762 all the software that you might reasonably want to
763 install if you didn't know what it was and don't have
764 specialized requirements. This is a much larger system
765 and includes the X Window System, a full TeX
766 distribution, and many applications. Note that
767 optional packages should not conflict with each other.
769 <tag><tt>extra</tt></tag>
771 This contains all packages that conflict with others
772 with required, important, standard or optional
773 priorities, or are only likely to be useful if you
774 already know what they are or have specialised
781 Packages must not depend on packages with lower priority
782 values (excluding build-time dependencies). In order to
783 ensure this, the priorities of one or more packages may need
792 <heading>Binary packages</heading>
795 The Debian GNU/Linux distribution is based on the Debian
796 package management system, called <prgn>dpkg</prgn>. Thus,
797 all packages in the Debian distribution must be provided
798 in the <tt>.deb</tt> file format.
802 <heading>The package name</heading>
805 Every package must have a name that's unique within the Debian
810 The package name is included in the control field
811 <tt>Package</tt>, the format of which is described
812 in <ref id="f-Package">.
813 The package name is also included as a part of the file name
814 of the <tt>.deb</tt> file.
819 <heading>The version of a package</heading>
822 Every package has a version number recorded in its
823 <tt>Version</tt> control file field, described in
824 <ref id="f-Version">.
828 The package management system imposes an ordering on version
829 numbers, so that it can tell whether packages are being up- or
830 downgraded and so that package system front end applications
831 can tell whether a package it finds available is newer than
832 the one installed on the system. The version number format
833 has the most significant parts (as far as comparison is
834 concerned) at the beginning.
838 If an upstream package has problematic version numbers they
839 should be converted to a sane form for use in the
840 <tt>Version</tt> field.
844 <heading>Version numbers based on dates</heading>
847 In general, Debian packages should use the same version
848 numbers as the upstream sources.
852 However, in some cases where the upstream version number is
853 based on a date (e.g., a development "snapshot" release) the
854 package management system cannot handle these version
855 numbers without epochs. For example, dpkg will consider
856 "96May01" to be greater than "96Dec24".
860 To prevent having to use epochs for every new upstream
861 version, the date based portion of the version number
862 should be changed to the following format in such cases:
863 "19960501", "19961224". It is up to the maintainer whether
864 they want to bother the upstream maintainer to change
865 the version numbers upstream, too.
869 Note that other version formats based on dates which are
870 parsed correctly by the package management system should
871 <em>not</em> be changed.
875 Native Debian packages (i.e., packages which have been
876 written especially for Debian) whose version numbers include
877 dates should always use the "YYYYMMDD" format.
884 <heading>The maintainer of a package</heading>
887 Every package must have a Debian maintainer (the
888 maintainer may be one person or a group of people
889 reachable from a common email address, such as a mailing
890 list). The maintainer is responsible for ensuring that
891 the package is placed in the appropriate distributions.
895 The maintainer must be specified in the
896 <tt>Maintainer</tt> control field with their correct name
897 and a working email address. If one person maintains
898 several packages, they should try to avoid having
899 different forms of their name and email address in
900 the <tt>Maintainer</tt> fields of those packages.
904 The format of the <tt>Maintainer</tt> control field is
905 described in <ref id="f-Maintainer">.
909 If the maintainer of a package quits from the Debian
910 project, "Debian QA Group"
911 <email>packages@qa.debian.org</email> takes over the
912 maintainership of the package until someone else
913 volunteers for that task. These packages are called
914 <em>orphaned packages</em>.<footnote>
915 The detailed procedure for doing this gracefully can
916 be found in the Debian Developer's Reference,
917 see <ref id="related">.
922 <sect id="descriptions">
923 <heading>The description of a package</heading>
926 Every Debian package must have an extended description
927 stored in the appropriate field of the control record.
928 The technical information about the format of the
929 <tt>Description</tt> field is in <ref id="f-Description">.
933 The description should describe the package (the program) to a
934 user (system administrator) who has never met it before so that
935 they have enough information to decide whether they want to
936 install it. This description should not just be copied verbatim
937 from the program's documentation.
941 Put important information first, both in the synopsis and
942 extended description. Sometimes only the first part of the
943 synopsis or of the description will be displayed. You can
944 assume that there will usually be a way to see the whole
945 extended description.
949 The description should also give information about the
950 significant dependencies and conflicts between this package
951 and others, so that the user knows why these dependencies and
952 conflicts have been declared.
956 Instructions for configuring or using the package should
957 not be included (that is what installation scripts,
958 manual pages, info files, etc., are for). Copyright
959 statements and other administrivia should not be included
960 either (that is what the copyright file is for).
963 <sect1 id="synopsis"><heading>The single line synopsis</heading>
966 The single line synopsis should be kept brief - certainly
971 Do not include the package name in the synopsis line. The
972 display software knows how to display this already, and you
973 do not need to state it. Remember that in many situations
974 the user may only see the synopsis line - make it as
975 informative as you can.
980 <sect1 id="extendeddesc"><heading>The extended description</heading>
983 Do not try to continue the single line synopsis into the
984 extended description. This will not work correctly when
985 the full description is displayed, and makes no sense
986 where only the summary (the single line synopsis) is
991 The extended description should describe what the package
992 does and how it relates to the rest of the system (in terms
993 of, for example, which subsystem it is which part of).
997 The description field needs to make sense to anyone, even
998 people who have no idea about any of the things the
999 package deals with.<footnote>
1000 The blurb that comes with a program in its
1001 announcements and/or <prgn>README</prgn> files is
1002 rarely suitable for use in a description. It is
1003 usually aimed at people who are already in the
1004 community where the package is used.
1013 <heading>Dependencies</heading>
1016 Every package must specify the dependency information
1017 about other packages that are required for the first to
1022 For example, a dependency entry must be provided for any
1023 shared libraries required by a dynamically-linked executable
1024 binary in a package.
1028 Packages are not required to declare any dependencies they
1029 have on other packages which are marked <tt>Essential</tt>
1030 (see below), and should not do so unless they depend on a
1031 particular version of that package.
1035 Sometimes, a package requires another package to be installed
1036 <em>and</em> configured before it can be installed. In this
1037 case, you must specify a <tt>Pre-Depends</tt> entry for
1042 You should not specify a <tt>Pre-Depends</tt> entry for a
1043 package before this has been discussed on the
1044 <tt>debian-devel</tt> mailing list and a consensus about
1045 doing that has been reached.
1049 The format of the package interrelationship control fields is
1050 described in <ref id="relationships">.
1054 <sect id="virtual_pkg">
1055 <heading>Virtual packages</heading>
1058 Sometimes, there are several packages which offer
1059 more-or-less the same functionality. In this case, it's
1060 useful to define a <em>virtual package</em> whose name
1061 describes that common functionality. (The virtual
1062 packages only exist logically, not physically; that's why
1063 they are called <em>virtual</em>.) The packages with this
1064 particular function will then <em>provide</em> the virtual
1065 package. Thus, any other package requiring that function
1066 can simply depend on the virtual package without having to
1067 specify all possible packages individually.
1071 All packages should use virtual package names where
1072 appropriate, and arrange to create new ones if necessary.
1073 They should not use virtual package names (except privately,
1074 amongst a cooperating group of packages) unless they have
1075 been agreed upon and appear in the list of virtual package
1076 names. (See also <ref id="virtual">)
1080 The latest version of the authoritative list of virtual
1081 package names can be found in the <tt>debian-policy</tt> package.
1082 It is also available from the Debian web mirrors at
1083 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1084 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1088 The procedure for updating the list is described in the preface
1095 <heading>Base system</heading>
1098 The <tt>base system</tt> is a minimum subset of the Debian
1099 GNU/Linux system that is installed before everything else
1100 on a new system. Thus, only very few packages are allowed
1101 to go into the <tt>base</tt> section to keep the required
1102 disk usage very small.
1106 Most of these packages will have the priority value
1107 <tt>required</tt> or at least <tt>important</tt>, and many
1108 of them will be tagged <tt>essential</tt> (see below).
1113 <heading>Essential packages</heading>
1116 Some packages are tagged <tt>essential</tt> for a system
1117 using the <tt>Essential</tt> control file field.
1118 The format of the <tt>Essential</tt> control field is
1119 described in <ref id="f-Essential">.
1123 Since these packages cannot be easily removed (one has to
1124 specify an extra <em>force option</em> to
1125 <prgn>dpkg</prgn> to do so), this flag must not be used
1126 unless absolutely necessary. A shared library package
1127 must not be tagged <tt>essential</tt>; dependencies will
1128 prevent its premature removal, and we need to be able to
1129 remove it when it has been superseded.
1133 Since dpkg will not prevent upgrading of other packages
1134 while an <tt>essential</tt> package is in an unconfigured
1135 state, all <tt>essential</tt> packages must supply all of
1136 their core functionality even when unconfigured. If the
1137 package cannot satisfy this requirement it must not be
1138 tagged as essential, and any packages depending on this
1139 package must instead have explicit dependency fields as
1144 You must not tag any packages <tt>essential</tt> before
1145 this has been discussed on the <tt>debian-devel</tt>
1146 mailing list and a consensus about doing that has been
1152 <heading>Tasks</heading>
1155 The Debian install process allows the user to choose from
1156 a number of common tasks which a Debian system can be used to
1157 perform. Selecting a task with <prgn>tasksel</prgn> causes
1158 a set of packages that are useful in performing that task to be
1163 This set of packages is all available packages which have the
1164 name of the selected task in the <tt>Task</tt> field of their
1165 control file. The format of this field is a list of tasks,
1166 separated by commas.
1170 You should not tag any packages as belonging to a task
1171 before this has been discussed on the
1172 <em>debian-devel</em> mailing list and a consensus about
1173 doing that has been reached.
1177 For third parties (and historical reasons), tasksel also
1178 supports constructing tasks based on <em>task
1179 packages</em>. These are packages whose names begin with
1180 <em>task-</em>. Task packages should not be included in the
1185 <sect id="maintscripts">
1186 <heading>Maintainer Scripts</heading>
1189 The package installation scripts should avoid producing
1190 output which is unnecessary for the user to see and
1191 should rely on <prgn>dpkg</prgn> to stave off boredom on
1192 the part of a user installing many packages. This means,
1193 amongst other things, using the <tt>--quiet</tt> option on
1194 <prgn>install-info</prgn>.
1198 Errors which occur during the execution of an installation
1199 script must be checked and the installation must not
1200 continue after an error.
1204 Note that in general <ref id="scripts"> applies to package
1205 maintainer scripts, too.
1209 You should not use <prgn>dpkg-divert</prgn> on a file
1210 belonging to another package without consulting the
1211 maintainer of that package first.
1215 All packages which supply an instance of a common command
1216 name (or, in general, filename) should generally use
1217 <prgn>update-alternatives</prgn>, so that they may be
1218 installed together. If <prgn>update-alternatives</prgn>
1219 is not used, then each package must use
1220 <tt>Conflicts</tt> to ensure that other packages are
1221 de-installed. (In this case, it may be appropriate to
1222 specify a conflict against earlier versions of something
1223 that previously did not use
1224 <prgn>update-alternatives</prgn>; this is an exception to
1225 the usual rule that versioned conflicts should be
1229 <sect1 id="maintscriptprompt">
1230 <heading>Prompting in maintainer scripts</heading>
1232 Package maintainer scripts may prompt the user if
1233 necessary. Prompting should be done by communicating
1234 through a program, such as <prgn>debconf</prgn>, which
1235 conforms to the Debian Configuration management
1236 specification, version 2 or higher. Prompting the user by
1237 other means, such as by hand<footnote>
1238 From the Jargon file: by hand 2. By extension,
1239 writing code which does something in an explicit or
1240 low-level way for which a presupplied library
1241 (<em>debconf, in this instance</em>) routine ought
1242 to have been available.
1243 </footnote>, is now deprecated.
1247 The Debian Configuration management specification is included
1248 in the <file>debconf_specification</file> files in the
1249 <package>debian-policy</package> package.
1250 It is also available from the Debian web mirrors at
1251 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1252 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1256 Packages which use the Debian Configuration management
1257 specification may contain an additional
1258 <prgn>config</prgn> script and a <tt>templates</tt>
1259 file in their control archive<footnote>
1260 The control.tar.gz inside the .deb.
1261 See <manref name="deb" section="5">.
1263 The <prgn>config</prgn> script might be run before the
1264 <prgn>preinst</prgn> script, and before the package is unpacked
1265 or any of its dependencies or pre-dependancies are satisfied.
1266 Therefore it must work using only the tools present in
1267 <em>essential</em> packages.<footnote>
1268 <package>Debconf</package> or another tool that
1269 implements the Debian Configuration management
1270 specification will also be installed, and any
1271 versioned dependencies on it will be satisfied
1272 before preconfiguration begins.
1277 Packages should try to minimize the amount of prompting
1278 they need to do, and they should ensure that the user
1279 will only ever be asked each question once. This means
1280 that packages should try to use appropriate shared
1281 configuration files (such as <file>/etc/papersize</file> and
1282 <file>/etc/news/server</file>), and shared
1283 <package>debconf</package> variables rather than each
1284 prompting for their own list of required pieces of
1289 It also means that an upgrade should not ask the same
1290 questions again, unless the user has used
1291 <tt>dpkg --purge</tt> to remove the package's configuration.
1292 The answers to configuration questions should be stored in an
1293 appropriate place in <file>/etc</file> so that the user can
1294 modify them, and how this has been done should be
1299 If a package has a vitally important piece of
1300 information to pass to the user (such as "don't run me
1301 as I am, you must edit the following configuration files
1302 first or you risk your system emitting badly-formatted
1303 messages"), it should display this in the
1304 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1305 prompt the user to hit return to acknowledge the
1306 message. Copyright messages do not count as vitally
1307 important (they belong in
1308 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1309 neither do instructions on how to use a program (these
1310 should be in on-line documentation, where all the users
1315 Any necessary prompting should almost always be confined
1316 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1317 script. If it is done in the <prgn>postinst</prgn>, it
1318 should be protected with a conditional so that
1319 unnecessary prompting doesn't happen if a package's
1320 installation fails and the <prgn>postinst</prgn> is
1321 called with <tt>abort-upgrade</tt>,
1322 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1332 <heading>Source packages</heading>
1334 <sect id="standardsversion">
1335 <heading>Standards conformance</heading>
1338 Source packages should specify the most recent version number
1339 of this policy document with which your package complied
1340 when it was last updated.
1344 This information may be used to file bug reports
1345 automatically if your package becomes too much out of date.
1349 The version is specified in the <tt>Standards-Version</tt>
1351 The format of the <tt>Standards-Version</tt> field is
1352 described in <ref id="f-Standards-Version">.
1356 You should regularly, and especially if your package has
1357 become out of date, check for the newest Policy Manual
1358 available and update your package, if necessary. When your
1359 package complies with the new standards you should update the
1360 <tt>Standards-Version</tt> source package field and
1361 release it.<footnote>
1362 See the file <file>upgrading-checklist</file> for
1363 information about policy which has changed between
1364 different versions of this document.
1370 <sect id="pkg-relations">
1371 <heading>Package relationships</heading>
1374 Source packages should specify which binary packages they
1375 require to be installed or not to be installed in order to
1376 build correctly. For example, if building a package
1377 requires a certain compiler, then the compiler should be
1378 specified as a build-time dependency.
1382 It is not necessary to explicitly specify build-time
1383 relationships on a minimal set of packages that are always
1384 needed to compile, link and put in a Debian package a
1385 standard "Hello World!" program written in C or C++. The
1386 required packages are called <em>build-essential</em>, and
1387 an informational list can be found in
1388 <file>/usr/share/doc/build-essential/list</file> (which is
1389 contained in the <tt>build-essential</tt>
1392 <list compact="compact">
1394 This allows maintaining the list separately
1395 from the policy documents (the list does not
1396 need the kind of control that the policy
1400 Having a separate package allows one to install
1401 the build-essential packages on a machine, as
1402 well as allowing other packages such as tasks to
1403 require installation of the build-essential
1404 packages using the depends relation.
1407 The separate package allows bug reports against
1408 the list to be categorized separately from
1409 the policy management process in the BTS.
1416 When specifying the set of build-time dependencies, one
1417 should list only those packages explicitly required by the
1418 build. It is not necessary to list packages which are
1419 required merely because some other package in the list of
1420 build-time dependencies depends on them.<footnote>
1421 The reason for this is that dependencies change, and
1422 you should list all those packages, and <em>only</em>
1423 those packages that <em>you</em> need directly. What
1424 others need is their business. For example, if you
1425 only link against <file>libimlib</file>, you will need to
1426 build-depend on <package>libimlib2-dev</package> but
1427 not against any <tt>libjpeg*</tt> packages, even
1428 though <tt>libimlib2-dev</tt> currently depends on
1429 them: installation of <package>libimlib2-dev</package>
1430 will automatically ensure that all of its run-time
1431 dependencies are satisfied.
1436 If build-time dependencies are specified, it must be
1437 possible to build the package and produce working binaries
1438 on a system with only essential and build-essential
1439 packages installed and also those required to satisfy the
1440 build-time relationships (including any implied
1441 relationships). In particular, this means that version
1442 clauses should be used rigorously in build-time
1443 relationships so that one cannot produce bad or
1444 inconsistently configured packages when the relationships
1445 are properly satisfied.
1449 <ref id="relationships"> explains the technical details.
1454 <heading>Changes to the upstream sources</heading>
1457 If changes to the source code are made that are not
1458 specific to the needs of the Debian system, they should be
1459 sent to the upstream authors in whatever form they prefer
1460 so as to be included in the upstream version of the
1465 If you need to configure the package differently for
1466 Debian or for Linux, and the upstream source doesn't
1467 provide a way to do so, you should add such configuration
1468 facilities (for example, a new <prgn>autoconf</prgn> test
1469 or <tt>#define</tt>) and send the patch to the upstream
1470 authors, with the default set to the way they originally
1471 had it. You can then easily override the default in your
1472 <file>debian/rules</file> or wherever is appropriate.
1476 You should make sure that the <prgn>configure</prgn> utility
1477 detects the correct architecture specification string
1478 (refer to <ref id="arch-spec"> for details).
1482 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1483 <prgn>configure</prgn> scripts are used, you should edit the
1484 <file>.in</file> files rather than editing the
1485 <prgn>Makefile</prgn> directly. This allows the user to
1486 reconfigure the package if necessary. You should
1487 <em>not</em> configure the package and edit the generated
1488 <prgn>Makefile</prgn>! This makes it impossible for someone
1489 else to later reconfigure the package without losing the
1495 <sect id="dpkgchangelog">
1496 <heading>Debian changelog: <file>debian/changelog</file></heading>
1499 Changes in the Debian version of the package should be
1500 briefly explained in the Debian changelog file
1501 <file>debian/changelog</file>.<footnote>
1503 Mistakes in changelogs are usually best rectified by
1504 making a new changelog entry rather than "rewriting
1505 history" by editing old changelog entries.
1508 This includes modifications
1509 made in the Debian package compared to the upstream one
1510 as well as other changes and updates to the package.
1512 Although there is nothing stopping an author who is also
1513 the Debian maintainer from using this changelog for all
1514 their changes, it will have to be renamed if the Debian
1515 and upstream maintainers become different people. In such
1516 a case, however, it might be better to maintain the package
1517 as a non-native package.
1526 The format of the <file>debian/changelog</file> allows the
1527 package building tools to discover which version of the package
1528 is being built and find out other release-specific information.
1532 That format is a series of entries like this:
1534 <example compact="compact">
1535 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1537 [optional blank line(s), stripped]
1539 * <var>change details</var>
1540 <var>more change details</var>
1542 [blank line(s), included in output of dpkg-parsechangelog]
1544 * <var>even more change details</var>
1546 [optional blank line(s), stripped]
1548 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1553 <var>package</var> and <var>version</var> are the source
1554 package name and version number.
1558 <var>distribution(s)</var> lists the distributions where
1559 this version should be installed when it is uploaded - it
1560 is copied to the <tt>Distribution</tt> field in the
1561 <file>.changes</file> file. See <ref id="f-Distribution">.
1565 <var>urgency</var> is the value for the <tt>Urgency</tt>
1566 field in the <file>.changes</file> file for the upload
1567 (see <ref id="f-Urgency">). It is not possible to specify
1568 an urgency containing commas; commas are used to separate
1569 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1570 <prgn>dpkg</prgn> changelog format (though there is
1571 currently only one useful <var>keyword</var>,
1572 <tt>urgency</tt>).<footnote>
1573 Recognised urgency values are <tt>low</tt>,
1574 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1575 They have an effect on how quickly a package will be
1576 considered for inclusion into the <tt>testing</tt>
1577 distribution, and give an indication of the importance
1578 of any fixes included in this upload.
1583 The change details may in fact be any series of lines
1584 starting with at least two spaces, but conventionally each
1585 change starts with an asterisk and a separating space and
1586 continuation lines are indented so as to bring them in
1587 line with the start of the text above. Blank lines may be
1588 used here to separate groups of changes, if desired.
1592 If this upload resolves bugs recorded in the Bug Tracking
1593 System (BTS), they may be automatically closed on the
1594 inclusion of this package into the Debian archive by
1595 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1596 in the change details.<footnote>
1597 To be precise, the string should match the following
1598 Perl regular expression:
1600 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1602 Then all of the bug numbers listed will be closed by the
1603 archive maintenance script (<prgn>katie</prgn>), or in
1604 the case of an NMU, marked as fixed.
1606 This information is conveyed via the <tt>Closes</tt> field
1607 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1611 The maintainer name and email address used in the changelog
1612 should be the details of the person uploading <em>this</em>
1613 version. They are <em>not</em> necessarily those of the
1614 usual package maintainer. The information here will be
1615 copied to the <tt>Changed-By</tt> field in the
1616 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1617 and then later used to send an acknowledgement when the
1618 upload has been installed.
1622 The <var>date</var> should be in RFC822 format<footnote>
1623 This is generated by the <prgn>822-date</prgn>
1625 </footnote>; it should include the time zone specified
1626 numerically, with the time zone name or abbreviation
1627 optionally present as a comment in parentheses.
1631 The first "title" line with the package name should start
1632 at the left hand margin; the "trailer" line with the
1633 maintainer and date details should be preceded by exactly
1634 one space. The maintainer details and the date must be
1635 separated by exactly two spaces.
1639 For more information on placement of the changelog files
1640 within binary packages, please see <ref id="changelogs">.
1643 <sect1><heading>Alternative changelog formats</heading>
1646 In non-experimental packages you must use a format for
1647 <file>debian/changelog</file> which is supported by the most
1648 recent released version of <prgn>dpkg</prgn>.
1652 It is possible to use a format different from the standard
1653 one by providing a changelog parser for the format you wish
1654 to use. The parser must have an API compatible with that
1655 expected by <prgn>dpkg-genchanges</prgn> and
1656 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1659 If there is general interest in the new format, you should
1660 contact the <package>dpkg</package> maintainer to have the
1661 parser script for it included in the <prgn>dpkg</prgn>
1662 package. (You will need to agree that the parser and its
1663 man page may be distributed under the GNU GPL, just as the rest
1664 of <prgn>dpkg</prgn> is.)
1671 <heading>Error trapping in makefiles</heading>
1674 When <prgn>make</prgn> invokes a command in a makefile
1675 (including your package's upstream makefiles and
1676 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1677 means that <prgn>sh</prgn>'s usual bad error handling
1678 properties apply: if you include a miniature script as one
1679 of the commands in your makefile you'll find that if you
1680 don't do anything about it then errors are not detected
1681 and <prgn>make</prgn> will blithely continue after
1686 Every time you put more than one shell command (this
1687 includes using a loop) in a makefile command you
1688 must make sure that errors are trapped. For
1689 simple compound commands, such as changing directory and
1690 then running a program, using <tt>&&</tt> rather
1691 than semicolon as a command separator is sufficient. For
1692 more complex commands including most loops and
1693 conditionals you should include a separate <tt>set -e</tt>
1694 command at the start of every makefile command that's
1695 actually one of these miniature shell scripts.
1699 <sect id="timestamps">
1700 <heading>Time Stamps</heading>
1702 Maintainers should preserve the modification times of the
1703 upstream source files in a package, as far as is reasonably
1705 The rationale is that there is some information conveyed
1706 by knowing the age of the file, for example, you could
1707 recognize that some documentation is very old by looking
1708 at the modification time, so it would be nice if the
1709 modification time of the upstream source would be
1715 <sect id="restrictions">
1716 <heading>Restrictions on objects in source packages</heading>
1719 The source package may not contain any hard links<footnote>
1721 This is not currently detected when building source
1722 packages, but only when extracting
1726 Hard links may be permitted at some point in the
1727 future, but would require a fair amount of
1730 </footnote>, device special files, sockets or setuid or
1731 setgid files.<footnote>
1732 Setgid directories are allowed.
1737 <sect id="debianrules">
1738 <heading>Main building script: <file>debian/rules</file></heading>
1741 This file must be an executable makefile, and contains the
1742 package-specific recipes for compiling the package and
1743 building binary package(s) from the source.
1747 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1748 so that it can be invoked by saying its name rather than
1749 invoking <prgn>make</prgn> explicitly.
1753 Since an interactive <file>debian/rules</file> script makes it
1754 impossible to auto-compile that package and also makes it
1755 hard for other people to reproduce the same binary
1756 package, all <em>required targets</em> MUST be
1757 non-interactive. At a minimum, required targets are the
1758 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1759 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1760 <em>binary-indep</em>, and <em>build</em>. It also follows
1761 that any target that these targets depend on must also be
1766 The targets are as follows (required unless stated otherwise):
1768 <tag><tt>build</tt></tag>
1771 The <tt>build</tt> target should perform all the
1772 configuration and compilation of the package.
1773 If a package has an interactive pre-build
1774 configuration routine, the Debianized source package
1775 must either be built after this has taken place (so
1776 that the binary package can be built without rerunning
1777 the configuration) or the configuration routine
1778 modified to become non-interactive. (The latter is
1779 preferable if there are architecture-specific features
1780 detected by the configuration routine.)
1784 For some packages, notably ones where the same
1785 source tree is compiled in different ways to produce
1786 two binary packages, the <tt>build</tt> target
1787 does not make much sense. For these packages it is
1788 good enough to provide two (or more) targets
1789 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1790 for each of the ways of building the package, and a
1791 <tt>build</tt> target that does nothing. The
1792 <tt>binary</tt> target will have to build the
1793 package in each of the possible ways and make the
1794 binary package out of each.
1798 The <tt>build</tt> target must not do anything
1799 that might require root privilege.
1803 The <tt>build</tt> target may need to run the
1804 <tt>clean</tt> target first - see below.
1808 When a package has a configuration and build routine
1809 which takes a long time, or when the makefiles are
1810 poorly designed, or when <tt>build</tt> needs to
1811 run <tt>clean</tt> first, it is a good idea to
1812 <tt>touch build</tt> when the build process is
1813 complete. This will ensure that if <tt>debian/rules
1814 build</tt> is run again it will not rebuild the whole
1816 Another common way to do this is for <tt>build</tt>
1817 to depend on <prgn>build-stamp</prgn> and to do
1818 nothing else, and for the <prgn>build-stamp</prgn>
1819 target to do the building and to <tt>touch
1820 build-stamp</tt> on completion. This is
1821 especially useful if the build routine creates a
1822 file or directory called <tt>build</tt>; in such a
1823 case, <tt>build</tt> will need to be listed as
1824 a phony target (i.e., as a dependency of the
1825 <tt>.PHONY</tt> target). See the documentation of
1826 <prgn>make</prgn> for more information on phony
1832 <tag><tt>build-arch</tt> (optional),
1833 <tt>build-indep</tt> (optional)
1837 A package may also provide both of the targets
1838 <tt>build-arch</tt> and <tt>build-indep</tt>.
1839 The <tt>build-arch</tt> target, if provided, should
1840 perform all the configuration and compilation required
1841 for producing all architecture-dependant binary packages
1842 (those packages for which the body of the
1843 <tt>Architecture</tt> field in <tt>debian/control</tt>
1844 is not <tt>all</tt>).
1845 Similarly, the <tt>build-indep</tt> target, if
1846 provided, should perform all the configuration and
1847 compilation required for producing all
1848 architecture-independent binary packages
1849 (those packages for which the body of the
1850 <tt>Architecture</tt> field in <tt>debian/control</tt>
1852 The <tt>build</tt> target should depend on those of the
1853 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1854 are provided in the rules file.
1858 If one or both of the targets <tt>build-arch</tt> and
1859 <tt>build-indep</tt> are not provided, then invoking
1860 <file>debian/rules</file> with one of the not-provided
1861 targets as arguments should produce a exit status code
1862 of 2. Usually this is provided automatically by make
1863 if the target is missing.
1867 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1868 must not do anything that might require root privilege.
1872 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1873 <tt>binary-indep</tt>
1877 The <tt>binary</tt> target must be all that is
1878 necessary for the user to build the binary package(s)
1879 produced from this source package. It is
1880 split into two parts: <prgn>binary-arch</prgn> builds
1881 the binary packages which are specific to a particular
1882 architecture, and <tt>binary-indep</tt> builds
1883 those which are not.
1886 <tt>binary</tt> may be (and commonly is) a target with
1887 no commands which simply depends on
1888 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1891 Both <tt>binary-*</tt> targets should depend on the
1892 <tt>build</tt> target, or on the appropriate
1893 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1894 provided, so that the package is built if it has not
1895 been already. It should then create the relevant
1896 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1897 make their control files and <prgn>dpkg-deb</prgn> to
1898 build them and place them in the parent of the top
1903 Both the <tt>binary-arch</tt> and
1904 <tt>binary-indep</tt> targets <em>must</em> exist.
1905 If one of them has nothing to do (which will always be
1906 the case if the source generates only a single binary
1907 package, whether architecture-dependent or not), it
1908 must still exist and must always succeed.
1912 The <tt>binary</tt> targets must be invoked as
1914 The <prgn>fakeroot</prgn> package often allows one
1915 to build a package correctly even without being
1921 <tag><tt>clean</tt></tag>
1924 This must undo any effects that the <tt>build</tt>
1925 and <tt>binary</tt> targets may have had, except
1926 that it should leave alone any output files created in
1927 the parent directory by a run of a <tt>binary</tt>
1932 If a <tt>build</tt> file is touched at the end of
1933 the <tt>build</tt> target, as suggested above, it
1934 should be removed as the first action that
1935 <tt>clean</tt> performs, so that running
1936 <tt>build</tt> again after an interrupted
1937 <tt>clean</tt> doesn't think that everything is
1942 The <tt>clean</tt> target may need to be
1943 invoked as root if <tt>binary</tt> has been
1944 invoked since the last <tt>clean</tt>, or if
1945 <tt>build</tt> has been invoked as root (since
1946 <tt>build</tt> may create directories, for
1951 <tag><tt>get-orig-source</tt> (optional)</tag>
1954 This target fetches the most recent version of the
1955 original source package from a canonical archive site
1956 (via FTP or WWW, for example), does any necessary
1957 rearrangement to turn it into the original source
1958 tar file format described below, and leaves it in the
1963 This target may be invoked in any directory, and
1964 should take care to clean up any temporary files it
1969 This target is optional, but providing it if
1970 possible is a good idea.
1976 The <tt>build</tt>, <tt>binary</tt> and
1977 <tt>clean</tt> targets must be invoked with the current
1978 directory being the package's top-level directory.
1983 Additional targets may exist in <file>debian/rules</file>,
1984 either as published or undocumented interfaces or for the
1985 package's internal use.
1989 The architectures we build on and build for are determined
1990 by <prgn>make</prgn> variables using the utility
1991 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1992 You can determine the
1993 Debian architecture and the GNU style architecture
1994 specification string for the build machine (the machine type
1995 we are building on) as well as for the host machine (the
1996 machine type we are building for). Here is a list of
1997 supported <prgn>make</prgn> variables:
1998 <list compact="compact">
2000 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2003 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2004 specification string)
2007 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2008 <tt>DEB_*_GNU_TYPE</tt>)
2011 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2012 <tt>DEB_*_GNU_TYPE</tt>)
2014 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2015 the build machine or <tt>HOST</tt> for specification of the
2020 Backward compatibility can be provided in the rules file
2021 by setting the needed variables to suitable default
2022 values; please refer to the documentation of
2023 <prgn>dpkg-architecture</prgn> for details.
2027 It is important to understand that the <tt>DEB_*_ARCH</tt>
2028 string only determines which Debian architecture we are
2029 building on or for. It should not be used to get the CPU
2030 or system information; the GNU style variables should be
2035 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2036 <sect id="substvars">
2037 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2040 When <prgn>dpkg-gencontrol</prgn>,
2041 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2042 generate control files they perform variable substitutions
2043 on their output just before writing it. Variable
2044 substitutions have the form <tt>${<var>variable</var>}</tt>.
2045 The optional file <file>debian/substvars</file> contains
2046 variable substitutions to be used; variables can also be set
2047 directly from <file>debian/rules</file> using the <tt>-V</tt>
2048 option to the source packaging commands, and certain
2049 predefined variables are also available.
2053 The <file>debian/substvars</file> file is usually generated and
2054 modified dynamically by <file>debian/rules</file> targets, in
2055 which case it must be removed by the <tt>clean</tt> target.
2059 See <manref name="dpkg-source" section="1"> for full
2060 details about source variable substitutions, including the
2061 format of <file>debian/substvars</file>.</p>
2064 <sect id="debianfiles">
2065 <heading>Generated files list: <file>debian/files</file></heading>
2068 This file is not a permanent part of the source tree; it
2069 is used while building packages to record which files are
2070 being generated. <prgn>dpkg-genchanges</prgn> uses it
2071 when it generates a <file>.changes</file> file.
2075 It should not exist in a shipped source package, and so it
2076 (and any backup files or temporary files such as
2077 <file>files.new</file><footnote>
2078 <file>files.new</file> is used as a temporary file by
2079 <prgn>dpkg-gencontrol</prgn> and
2080 <prgn>dpkg-distaddfile</prgn> - they write a new
2081 version of <tt>files</tt> here before renaming it,
2082 to avoid leaving a corrupted copy if an error
2084 </footnote>) should be removed by the
2085 <tt>clean</tt> target. It may also be wise to
2086 ensure a fresh start by emptying or removing it at the
2087 start of the <tt>binary</tt> target.
2091 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2092 package, it adds an entry to <file>debian/files</file> for the
2093 <file>.deb</file> file that will be created when <tt>dpkg-deb
2094 --build</tt> is run for that binary package. So for most
2095 packages all that needs to be done with this file is to
2096 delete it in the <tt>clean</tt> target.
2100 If a package upload includes files besides the source
2101 package and any binary packages whose control files were
2102 made with <prgn>dpkg-gencontrol</prgn> then they should be
2103 placed in the parent of the package's top-level directory
2104 and <prgn>dpkg-distaddfile</prgn> should be called to add
2105 the file to the list in <file>debian/files</file>.</p>
2111 <chapt id="controlfields">
2112 <heading>Control files and their fields</heading>
2115 The package management system manipulates data represented in
2116 a common format, known as <em>control data</em>, stored in
2117 <em>control files</em>.
2118 Control files are used for source packages, binary packages and
2119 the <file>.changes</file> files which control the installation
2120 of uploaded files<footnote>
2121 <prgn>dpkg</prgn>'s internal databases are in a similar
2126 <sect id="controlsyntax">
2127 <heading>Syntax of control files</heading>
2130 A control file consists of one or more paragraphs of
2132 The paragraphs are also sometimes referred to as stanzas.
2134 The paragraphs are separated by blank lines. Some control
2135 files allow only one paragraph; others allow several, in
2136 which case each paragraph usually refers to a different
2137 package. (For example, in source packages, the first
2138 paragraph refers to the source package, and later paragraphs
2139 refer to binary packages generated from the source.)
2143 Each paragraph consists of a series of data fields; each
2144 field consists of the field name, followed by a colon and
2145 then the data/value associated with that field. It ends at
2146 the end of the line. Horizontal whitespace (spaces and
2147 tabs) may occur immediately before or after the value and is
2148 ignored there; it is conventional to put a single space
2149 after the colon. For example, a field might be:
2150 <example compact="compact">
2153 the field name is <tt>Package</tt> and the field value
2158 Some fields' values may span several lines; in this case
2159 each continuation line must start with a space or a tab.
2160 Any trailing spaces or tabs at the end of individual
2161 lines of a field value are ignored.
2165 Except where otherwise stated, only a single line of data is
2166 allowed and whitespace is not significant in a field body.
2167 Whitespace must not appear inside names (of packages,
2168 architectures, files or anything else) or version numbers,
2169 or between the characters of multi-character version
2174 Field names are not case-sensitive, but it is usual to
2175 capitalize the field names using mixed case as shown below.
2179 Blank lines, or lines consisting only of spaces and tabs,
2180 are not allowed within field values or between fields - that
2181 would mean a new paragraph.
2186 <sect id="sourcecontrolfiles">
2187 <heading>Source package control files -- <file>debian/control</file></heading>
2190 The <file>debian/control</file> file contains the most vital
2191 (and version-independent) information about the source package
2192 and about the binary packages it creates.
2196 The first paragraph of the control file contains information about
2197 the source package in general. The subsequent sets each describe a
2198 binary package that the source tree builds.
2202 The fields in the general paragraph (the first one, for the source
2205 <list compact="compact">
2206 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2207 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2208 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2209 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2210 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2211 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2212 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2217 The fields in the binary package paragraphs are:
2219 <list compact="compact">
2220 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2221 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2222 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2223 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2224 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2225 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2226 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2231 The syntax and semantics of the fields are described below.
2237 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2238 generate control files for binary packages (see below), by
2239 <prgn>dpkg-genchanges</prgn> to generate the
2240 <tt>.changes</tt> file to accompany the upload, and by
2241 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2242 source control file as part of a source archive.
2246 The fields here may contain variable references - their
2247 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2248 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2249 when they generate output control files.
2250 See <ref id="substvars"> for details.
2255 <sect id="binarycontrolfiles">
2256 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2259 The <file>DEBIAN/control</file> file contains the most vital
2260 (and version-dependent) information about a binary package.
2264 The fields in this file are:
2266 <list compact="compact">
2267 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2268 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2269 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2270 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2271 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2272 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2273 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2274 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2275 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2276 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2277 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2282 <sect id="debiansourcecontrolfiles">
2283 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2286 This file contains a series of fields, identified and
2287 separated just like the fields in the control file of
2288 a binary package. The fields are listed below; their
2289 syntax is described above, in <ref id="pkg-controlfields">.
2291 <list compact="compact">
2292 <item><qref id="f-Format"><tt>Format</tt></qref></item>
2293 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2294 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2295 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2296 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2297 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2298 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2299 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2300 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2301 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2306 The source package control file is generated by
2307 <prgn>dpkg-source</prgn> when it builds the source
2308 archive, from other files in the source package,
2309 described above. When unpacking, it is checked against
2310 the files and directories in the other parts of the
2316 <sect id="debianchangesfiles">
2317 <heading>Debian changes files -- <file>.changes</file></heading>
2320 The .changes files are used by the Debian archive maintenance
2321 software to process updates to packages. They contain one
2322 paragraph which contains information from the
2323 <tt>debian/control</tt> file and other data about the
2324 source package gathered via <tt>debian/changelog</tt>
2325 and <tt>debian/rules</tt>.
2329 The fields in this file are:
2331 <list compact="compact">
2332 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2333 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2334 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2335 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2336 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2337 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2339 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2340 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2341 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2342 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2343 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2344 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2345 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2350 <sect id="controlfieldslist">
2351 <heading>List of fields</heading>
2353 <sect1 id="f-Source">
2354 <heading><tt>Source</tt></heading>
2357 This field identifies the source package name.
2361 In a main source control information, a <file>.changes</file>
2362 or a <file>.dsc</file> file this may contain only the name
2363 of the source package.
2367 In the control file of a binary package it may be followed
2368 by a version number in parentheses<footnote>
2369 It is customary to leave a space after the package name
2370 if a version number is specified.
2372 This version number may be omitted (and is, by
2373 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2374 the <tt>Version</tt> field of the binary package in
2375 question. The field itself may be omitted from a binary
2376 package control file when the source package has the same
2377 name and version as the binary package.
2381 <sect1 id="f-Maintainer">
2382 <heading><tt>Maintainer</tt></heading>
2385 The package maintainer's name and email address. The name
2386 should come first, then the email address inside angle
2387 brackets <tt><></tt> (in RFC822 format).
2391 If the maintainer's name contains a full stop then the
2392 whole field will not work directly as an email address due
2393 to a misfeature in the syntax specified in RFC822; a
2394 program using this field as an address must check for this
2395 and correct the problem if necessary (for example by
2396 putting the name in round brackets and moving it to the
2397 end, and bringing the email address forward).
2401 <sect1 id="f-Uploaders">
2402 <heading><tt>Uploaders</tt></heading>
2405 List of the names and email addresses of
2406 co-maintaintainers of the package, if any. If the package
2407 has other maintainers beside the one named in the <qref
2408 id="f-Maintainer">Maintainer field</qref>, they their
2409 names and email addresses should be listed here. The
2410 format is the same as that of the Maintainer tag, and
2411 multiple entries should be comma separated. This is an
2416 <sect1 id="f-Changed-By">
2417 <heading><tt>Changed-By</tt></heading>
2420 The name and email address of the person who changed the
2421 said package. Usually the name of the maintainer.
2422 All the rules for the Maintainer field apply here, too.
2426 <sect1 id="f-Section">
2427 <heading><tt>Section</tt></heading>
2430 This field specifies an application area into which the package
2431 has been classified. See <ref id="subsections">.
2435 When it appears in the <file>debian/control</file> file,
2436 it gives the value for the subfield of the same name in
2437 the <tt>Files</tt> field of the <file>.changes</file> file.
2438 It also gives the default for the same field in the binary
2443 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2444 field in the control file of a binary package - use the
2445 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2449 <sect1 id="f-Priority">
2450 <heading><tt>Priority</tt></heading>
2453 This field represents how important that it is that the user
2454 have the package installed. See <ref id="priorities">.
2458 When it appears in the <file>debian/control</file> file,
2459 it gives the value for the subfield of the same name in
2460 the <tt>Files</tt> field of the <file>.changes</file> file.
2461 It also gives the default for the same field in the binary
2466 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2467 field in the control file of a binary package - use the
2468 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2472 <sect1 id="f-Package">
2473 <heading><tt>Package</tt></heading>
2476 The name of the binary package.
2480 Package names must consist only of lower case letters
2481 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2482 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2483 They must be at least two characters long and must start
2484 with an alphanumeric character.
2488 <sect1 id="f-Architecture">
2489 <heading><tt>Architecture</tt></heading>
2492 Depending on context and the control file used, the
2493 <tt>Architecture</tt> field can include the following sets of
2496 <item>A unique single word identifying a Debian machine
2497 architecture, see <ref id="arch-spec">.
2498 <item><tt>all</tt>, which indicates an
2499 architecture-independent package.
2500 <item><tt>any</tt>, which indicates a package available
2501 for building on any architecture.
2502 <item><tt>source</tt>, which indicates a source package.
2507 In the main <file>debian/control</file> file in the source
2508 package, or in the source package control file
2509 <file>.dsc</file>, one may specify a list of architectures
2510 separated by spaces, or the special values <tt>any</tt> or
2515 Specifying <tt>any</tt> indicates that the source package
2516 isn't dependent on any particular architecture and should
2517 compile fine on any one. The produced binary package(s)
2518 will be specific to whatever the current build architecture
2520 This is the most often used setting, and is recommended
2521 for new packages that aren't <tt>Architecture: all</tt>.
2526 Specifying a list of architectures indicates that the source
2527 will build an architecture-dependent package, and will only
2528 work correctly on the listed architectures.<footnote>
2529 This is a setting used for a minority of cases where the
2530 program is not portable. Generally, it should not be used
2536 In a <file>.changes</file> file, the <tt>Architecture</tt>
2537 field lists the architecture(s) of the package(s)
2538 currently being uploaded. This will be a list; if the
2539 source for the package is also being uploaded, the special
2540 entry <tt>source</tt> is also present.
2544 See <ref id="debianrules"> for information how to get the
2545 architecture for the build process.
2549 <sect1 id="f-Essential">
2550 <heading><tt>Essential</tt></heading>
2553 This is a boolean field which may occur only in the
2554 control file of a binary package or in a per-package fields
2555 paragraph of a main source control data file.
2559 If set to <tt>yes</tt> then the package management system
2560 will refuse to remove the package (upgrading and replacing
2561 it is still possible). The other possible value is <tt>no</tt>,
2562 which is the same as not having the field at all.
2567 <heading>Package interrelationship fields:
2568 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2569 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2570 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2574 These fields describe the package's relationships with
2575 other packages. Their syntax and semantics are described
2576 in <ref id="relationships">.</p>
2579 <sect1 id="f-Standards-Version">
2580 <heading><tt>Standards-Version</tt></heading>
2583 The most recent version of the standards (the policy
2584 manual and associated texts) with which the package
2589 The version number has four components: major and minor
2590 version number and major and minor patch level. When the
2591 standards change in a way that requires every package to
2592 change the major number will be changed. Significant
2593 changes that will require work in many packages will be
2594 signaled by a change to the minor number. The major patch
2595 level will be changed for any change to the meaning of the
2596 standards, however small; the minor patch level will be
2597 changed when only cosmetic, typographical or other edits
2598 are made which neither change the meaning of the document
2599 nor affect the contents of packages.
2603 Thus only the first three components of the policy version
2604 are significant in the <em>Standards-Version</em> control
2605 field, and so either these three components or the all
2606 four components may be specified.<footnote>
2607 In the past, people specified the full version number
2608 in the Standards-Version field, for example "2.3.0.0".
2609 Since minor patch-level changes don't introduce new
2610 policy, it was thought it would be better to relax
2611 policy and only require the first 3 components to be
2612 specified, in this example "2.3.0". All four
2613 components may still be used if someone wishes to do so.
2619 <sect1 id="f-Version">
2620 <heading><tt>Version</tt></heading>
2623 The version number of a package. The format is:
2624 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2628 The three components here are:
2630 <tag><var>epoch</var></tag>
2633 This is a single (generally small) unsigned integer. It
2634 may be omitted, in which case zero is assumed. If it is
2635 omitted then the <var>upstream_version</var> may not
2640 It is provided to allow mistakes in the version numbers
2641 of older versions of a package, and also a package's
2642 previous version numbering schemes, to be left behind.
2646 <tag><var>upstream_version</var></tag>
2649 This is the main part of the version number. It is
2650 usually the version number of the original ("upstream")
2651 package from which the <file>.deb</file> file has been made,
2652 if this is applicable. Usually this will be in the same
2653 format as that specified by the upstream author(s);
2654 however, it may need to be reformatted to fit into the
2655 package management system's format and comparison
2660 The comparison behavior of the package management system
2661 with respect to the <var>upstream_version</var> is
2662 described below. The <var>upstream_version</var>
2663 portion of the version number is mandatory.
2667 The <var>upstream_version</var> may contain only
2668 alphanumerics<footnote>
2669 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2671 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2672 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2673 start with a digit. If there is no
2674 <var>debian_revision</var> then hyphens are not allowed;
2675 if there is no <var>epoch</var> then colons are not
2680 <tag><var>debian_revision</var></tag>
2683 This part of the version number specifies the version of
2684 the Debian package based on the upstream version. It
2685 may contain only alphanumerics and the characters
2686 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2687 compared in the same way as the
2688 <var>upstream_version</var> is.
2692 It is optional; if it isn't present then the
2693 <var>upstream_version</var> may not contain a hyphen.
2694 This format represents the case where a piece of
2695 software was written specifically to be turned into a
2696 Debian package, and so there is only one "debianization"
2697 of it and therefore no revision indication is required.
2701 It is conventional to restart the
2702 <var>debian_revision</var> at <tt>1</tt> each time the
2703 <var>upstream_version</var> is increased.
2707 The package management system will break the version
2708 number apart at the last hyphen in the string (if there
2709 is one) to determine the <var>upstream_version</var> and
2710 <var>debian_revision</var>. The absence of a
2711 <var>debian_revision</var> compares earlier than the
2712 presence of one (but note that the
2713 <var>debian_revision</var> is the least significant part
2714 of the version number).
2721 The <var>upstream_version</var> and <var>debian_revision</var>
2722 parts are compared by the package management system using the
2727 The strings are compared from left to right.
2731 First the initial part of each string consisting entirely of
2732 non-digit characters is determined. These two parts (one of
2733 which may be empty) are compared lexically. If a difference
2734 is found it is returned. The lexical comparison is a
2735 comparison of ASCII values modified so that all the letters
2736 sort earlier than all the non-letters.
2740 Then the initial part of the remainder of each string which
2741 consists entirely of digit characters is determined. The
2742 numerical values of these two parts are compared, and any
2743 difference found is returned as the result of the comparison.
2744 For these purposes an empty string (which can only occur at
2745 the end of one or both version strings being compared) counts
2750 These two steps (comparing and removing initial non-digit
2751 strings and initial digit strings) are repeated until a
2752 difference is found or both strings are exhausted.
2756 Note that the purpose of epochs is to allow us to leave behind
2757 mistakes in version numbering, and to cope with situations
2758 where the version numbering scheme changes. It is
2759 <em>not</em> intended to cope with version numbers containing
2760 strings of letters which the package management system cannot
2761 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2762 silly orderings (the author of this manual has heard of a
2763 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2764 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2765 <tt>2</tt> and so forth).
2769 <sect1 id="f-Description">
2770 <heading><tt>Description</tt></heading>
2773 In a source or binary control file, the <tt>Description</tt>
2774 field contains a description of the binary package, consisting
2775 of two parts, the synopsis or the short description, and the
2776 long description. The field's format is as follows:
2781 Description: <single line synopsis>
2782 <extended description over several lines>
2787 The lines in the extended description can have these formats:
2793 Those starting with a single space are part of a paragraph.
2794 Successive lines of this form will be word-wrapped when
2795 displayed. The leading space will usually be stripped off.
2799 Those starting with two or more spaces. These will be
2800 displayed verbatim. If the display cannot be panned
2801 horizontally, the displaying program will linewrap them "hard"
2802 (i.e., without taking account of word breaks). If it can they
2803 will be allowed to trail off to the right. None, one or two
2804 initial spaces may be deleted, but the number of spaces
2805 deleted from each line will be the same (so that you can have
2806 indenting work correctly, for example).
2810 Those containing a single space followed by a single full stop
2811 character. These are rendered as blank lines. This is the
2812 <em>only</em> way to get a blank line<footnote>
2813 Completely empty lines will not be rendered as blank lines.
2814 Instead, they will cause the parser to think you're starting
2815 a whole new record in the control file, and will therefore
2816 likely abort with an error.
2821 Those containing a space, a full stop and some more characters.
2822 These are for future expansion. Do not use them.
2828 Do not use tab characters. Their effect is not predictable.
2832 See <ref id="descriptions"> for further information on this.
2836 In a <file>.changes</file> file, the <tt>Description</tt> field
2837 contains a summary of the descriptions for the packages being
2842 The part of the field before the first newline is empty;
2843 thereafter each line has the name of a binary package and
2844 the summary description line from that binary package.
2845 Each line is indented by one space.
2850 <sect1 id="f-Distribution">
2851 <heading><tt>Distribution</tt></heading>
2854 In a <file>.changes</file> file or parsed changelog output
2855 this contains the (space-separated) name(s) of the
2856 distribution(s) where this version of the package should
2857 be installed. Valid distributions are determined by the
2858 archive maintainers.<footnote>
2859 Current distribution names are:
2860 <taglist compact="compact">
2861 <tag><em>stable</em></tag>
2863 This is the current "released" version of Debian
2864 GNU/Linux. Once the distribution is
2865 <em>stable</em> only security fixes and other
2866 major bug fixes are allowed. When changes are
2867 made to this distribution, the release number is
2868 increased (for example: 2.2r1 becomes 2.2r2 then
2872 <tag><em>unstable</em></tag>
2874 This distribution value refers to the
2875 <em>developmental</em> part of the Debian
2876 distribution tree. New packages, new upstream
2877 versions of packages and bug fixes go into the
2878 <em>unstable</em> directory tree. Download from
2879 this distribution at your own risk.
2882 <tag><em>testing</em></tag>
2884 This distribution value refers to the
2885 <em>testing</em> part of the Debian distribution
2886 tree. It receives its packages from the
2887 unstable distribution after a short time lag to
2888 ensure that there are no major issues with the
2889 unstable packages. It is less prone to breakage
2890 than unstable, but still risky. It is not
2891 possible to upload packages directly to
2895 <tag><em>frozen</em></tag>
2897 From time to time, the <em>testing</em>
2898 distribution enters a state of "code-freeze" in
2899 anticipation of release as a <em>stable</em>
2900 version. During this period of testing only
2901 fixes for existing or newly-discovered bugs will
2902 be allowed. The exact details of this stage are
2903 determined by the Release Manager.
2906 <tag><em>experimental</em></tag>
2908 The packages with this distribution value are
2909 deemed by their maintainers to be high
2910 risk. Oftentimes they represent early beta or
2911 developmental packages from various sources that
2912 the maintainers want people to try, but are not
2913 ready to be a part of the other parts of the
2914 Debian distribution tree. Download at your own
2920 You should list <em>all</em> distributions that the
2921 package should be installed into.
2925 More information is available in the Debian Developer's
2926 Reference, section "The Debian archive".
2933 <heading><tt>Date</tt></heading>
2936 This field includes the date the package was built or last edited.
2940 The value of this field is usually extracted from the
2941 <file>debian/changelog</file> file - see
2942 <ref id="dpkgchangelog">).
2946 <sect1 id="f-Format">
2947 <heading><tt>Format</tt></heading>
2950 This field specifies a format revision for the file.
2951 The most current format described in the Policy Manual
2952 is version <strong>1.5</strong>. The syntax of the
2953 format value is the same as that of a package version
2954 number except that no epoch or Debian revision is allowed
2955 - see <ref id="f-Version">.
2959 <sect1 id="f-Urgency">
2960 <heading><tt>Urgency</tt></heading>
2963 This is a description of how important it is to upgrade to
2964 this version from previous ones. It consists of a single
2965 keyword usually taking one of the values <tt>low</tt>,
2966 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2967 followed by an optional commentary (separated by a space)
2968 which is usually in parentheses. For example:
2971 Urgency: low (HIGH for users of diversions)
2977 The value of this field is usually extracted from the
2978 <file>debian/changelog</file> file - see
2979 <ref id="dpkgchangelog">.
2983 <sect1 id="f-Changes">
2984 <heading><tt>Changes</tt></heading>
2987 This field contains the human-readable changes data, describing
2988 the differences between the last version and the current one.
2992 There should be nothing in this field before the first
2993 newline; all the subsequent lines must be indented by at
2994 least one space; blank lines must be represented by a line
2995 consiting only of a space and a full stop.
2999 The value of this field is usually extracted from the
3000 <file>debian/changelog</file> file - see
3001 <ref id="dpkgchangelog">).
3005 Each version's change information should be preceded by a
3006 "title" line giving at least the version, distribution(s)
3007 and urgency, in a human-readable way.
3011 If data from several versions is being returned the entry
3012 for the most recent version should be returned first, and
3013 entries should be separated by the representation of a
3014 blank line (the "title" line may also be followed by the
3015 representation of blank line).
3019 <sect1 id="f-Binary">
3020 <heading><tt>Binary</tt></heading>
3023 This field is a list of binary packages.
3027 When it appears in the <file>.dsc</file> file it is the list
3028 of binary packages which a source package can produce. It
3029 does not necessarily produce all of these binary packages
3030 for every architecture. The source control file doesn't
3031 contain details of which architectures are appropriate for
3032 which of the binary packages.
3036 When it appears in a <file>.changes</file> file it lists the
3037 names of the binary packages actually being uploaded.
3041 The syntax is a list of binary packages separated by
3043 A space after each comma is conventional.
3044 </footnote>. Currently the packages must be separated using
3045 only spaces in the <file>.changes</file> file.
3049 <sect1 id="f-Installed-Size">
3050 <heading><tt>Installed-Size</tt></heading>
3053 This field appears in the control files of binary
3054 packages, and in the <file>Packages</file> files. It gives
3055 the total amount of disk space required to install the
3060 The disk space is represented in kilobytes as a simple
3065 <sect1 id="f-Files">
3066 <heading><tt>Files</tt></heading>
3069 This field contains a list of files with information about
3070 each one. The exact information and syntax varies with
3071 the context. In all cases the part of the field
3072 contents on the same line as the field name is empty. The
3073 remainder of the field is one line per file, each line
3074 being indented by one space and containing a number of
3075 sub-fields separated by spaces.
3079 In the <file>.dsc</file> file, each line contains the MD5
3080 checksum, size and filename of the tar file and (if applicable)
3081 diff file which make up the remainder of the source
3083 That is, the parts which are not the <tt>.dsc</tt>.
3085 The exact forms of the filenames are described
3086 in <ref id="pkg-sourcearchives">.
3090 In the <file>.changes</file> file this contains one line per
3091 file being uploaded. Each line contains the MD5 checksum,
3092 size, section and priority and the filename.
3093 The <qref id="f-Section">section</qref>
3094 and <qref id="f-Priority">priority</qref>
3095 are the values of the corresponding fields in
3096 the main source control file. If no section or priority is
3097 specified then <tt>-</tt> should be used, though section
3098 and priority values must be specified for new packages to
3099 be installed properly.
3103 The special value <tt>byhand</tt> for the section in a
3104 <tt>.changes</tt> file indicates that the file in question
3105 is not an ordinary package file and must by installed by
3106 hand by the distribution maintainers. If the section is
3107 <tt>byhand</tt> the priority should be <tt>-</tt>.
3111 If a new Debian revision of a package is being shipped and
3112 no new original source archive is being distributed the
3113 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3114 entry for the original source archive
3115 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3116 but the <file>.changes</file> file should leave it out. In
3117 this case the original source archive on the distribution
3118 site must match exactly, byte-for-byte, the original
3119 source archive which was used to generate the
3120 <file>.dsc</file> file and diff which are being uploaded.</p>
3123 <sect1 id="f-Closes">
3124 <heading><tt>Closes</tt></heading>
3127 A space-separated list of bug report numbers that the upload
3128 governed by the .changes file closes.
3135 <heading>User-defined fields</heading>
3138 Additional user-defined fields may be added to the
3139 source package control file. Such fields will be
3140 ignored, and not copied to (for example) binary or
3141 source package control files or upload control files.
3145 If you wish to add additional unsupported fields to
3146 these output files you should use the mechanism
3151 Fields in the main source control information file with
3152 names starting <tt>X</tt>, followed by one or more of
3153 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3154 be copied to the output files. Only the part of the
3155 field name after the hyphen will be used in the output
3156 file. Where the letter <tt>B</tt> is used the field
3157 will appear in binary package control files, where the
3158 letter <tt>S</tt> is used in source package control
3159 files and where <tt>C</tt> is used in upload control
3160 (<tt>.changes</tt>) files.
3164 For example, if the main source information control file
3167 XBS-Comment: I stand between the candle and the star.
3169 then the binary and source package control files will contain the
3172 Comment: I stand between the candle and the star.
3181 <chapt id="maintainerscripts">
3182 <heading>Package maintainer scripts and installation procedure</heading>
3185 <heading>Introduction to package maintainer scripts</heading>
3188 It is possible to supply scripts as part of a package which
3189 the package management system will run for you when your
3190 package is installed, upgraded or removed.
3194 These scripts are the files <prgn>preinst</prgn>,
3195 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3196 control area of the package. They must be proper executable
3197 files; if they are scripts (which is recommended), they must
3198 start with the usual <tt>#!</tt> convention. They should be
3199 readable and executable by anyone, and not world-writable.
3203 The package management system looks at the exit status from
3204 these scripts. It is important that they exit with a
3205 non-zero status if there is an error, so that the package
3206 management system can stop its processing. For shell
3207 scripts this means that you <em>almost always</em> need to
3208 use <tt>set -e</tt> (this is usually true when writing shell
3209 scripts, in fact). It is also important, of course, that
3210 they don't exit with a non-zero status if everything went
3215 When a package is upgraded a combination of the scripts from
3216 the old and new packages is called during the upgrade
3217 procedure. If your scripts are going to be at all
3218 complicated you need to be aware of this, and may need to
3219 check the arguments to your scripts.
3223 Broadly speaking the <prgn>preinst</prgn> is called before
3224 (a particular version of) a package is installed, and the
3225 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3226 before (a version of) a package is removed and the
3227 <prgn>postrm</prgn> afterwards.
3231 Programs called from maintainer scripts should not normally
3232 have a path prepended to them. Before installation is
3233 started, the package management system checks to see if the
3234 programs <prgn>ldconfig</prgn>,
3235 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3236 and <prgn>update-rc.d</prgn> can be found via the
3237 <tt>PATH</tt> environment variable. Those programs, and any
3238 other program that one would expect to be on the
3239 <tt>PATH</tt>, should thus be invoked without an absolute
3240 pathname. Maintainer scripts should also not reset the
3241 <tt>PATH</tt>, though they might choose to modify it by
3242 prepending or appending package-specific directories. These
3243 considerations really apply to all shell scripts.</p>
3246 <sect id="idempotency">
3247 <heading>Maintainer scripts Idempotency</heading>
3250 It is necessary for the error recovery procedures that the
3251 scripts be idempotent. This means that if it is run
3252 successfully, and then it is called again, it doesn't bomb
3253 out or cause any harm, but just ensures that everything is
3254 the way it ought to be. If the first call failed, or
3255 aborted half way through for some reason, the second call
3256 should merely do the things that were left undone the first
3257 time, if any, and exit with a success status if everything
3259 This is so that if an error occurs, the user interrupts
3260 <prgn>dpkg</prgn> or some other unforeseen circumstance
3261 happens you don't leave the user with a badly-broken
3262 package when <prgn>dpkg</prgn> attempts to repeat the
3268 <sect id="controllingterminal">
3269 <heading>Controlling terminal for maintainer scripts</heading>
3272 The maintainer scripts are guaranteed to run with a
3273 controlling terminal and can interact with the user.
3274 If they need to prompt for passwords, do full-screen
3275 interaction or something similar you should do these
3276 things to and from <file>/dev/tty</file>, since
3277 <prgn>dpkg</prgn> will at some point redirect scripts'
3278 standard input and output so that it can log the
3279 installation process. Likewise, because these scripts
3280 may be executed with standard output redirected into a
3281 pipe for logging purposes, Perl scripts should set
3282 unbuffered output by setting <tt>$|=1</tt> so that the
3283 output is printed immediately rather than being
3288 Each script should return a zero exit status for
3289 success, or a nonzero one for failure.
3293 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3298 <list compact="compact">
3300 <var>new-preinst</var> <tt>install</tt>
3303 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3306 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3309 <var>old-preinst</var> <tt>abort-upgrade</tt>
3310 <var>new-version</var>
3315 <list compact="compact">
3317 <var>postinst</var> <tt>configure</tt>
3318 <var>most-recently-configured-version</var>
3321 <var>old-postinst</var> <tt>abort-upgrade</tt>
3322 <var>new-version</var>
3325 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3326 <tt>in-favour</tt> <var>package</var>
3327 <var>new-version</var>
3330 <var>deconfigured's-postinst</var>
3331 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3332 <var>failed-install-package</var> <var>version</var>
3333 <tt>removing</tt> <var>conflicting-package</var>
3339 <list compact="compact">
3341 <var>prerm</var> <tt>remove</tt>
3344 <var>old-prerm</var> <tt>upgrade</tt>
3345 <var>new-version</var>
3348 <var>new-prerm</var> <tt>failed-upgrade</tt>
3349 <var>old-version</var>
3352 <var>conflictor's-prerm</var> <tt>remove</tt>
3353 <tt>in-favour</tt> <var>package</var>
3354 <var>new-version</var>
3357 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3358 <tt>in-favour</tt> <var>package-being-installed</var>
3359 <var>version</var> <tt>removing</tt>
3360 <var>conflicting-package</var>
3366 <list compact="compact">
3368 <var>postrm</var> <tt>remove</tt>
3371 <var>postrm</var> <tt>purge</tt>
3374 <var>old-postrm</var> <tt>upgrade</tt>
3375 <var>new-version</var>
3378 <var>new-postrm</var> <tt>failed-upgrade</tt>
3379 <var>old-version</var>
3382 <var>new-postrm</var> <tt>abort-install</tt>
3385 <var>new-postrm</var> <tt>abort-install</tt>
3386 <var>old-version</var>
3389 <var>new-postrm</var> <tt>abort-upgrade</tt>
3390 <var>old-version</var>
3393 <var>disappearer's-postrm</var> <tt>disappear</tt>
3394 <var>overwriter</var>
3395 <var>overwriter-version</var>
3401 <sect id="unpackphase">
3402 <heading>Details of unpack phase of installation or upgrade</heading>
3405 The procedure on installation/upgrade/overwrite/disappear
3406 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3407 stage of <tt>dpkg --install</tt>) is as follows. In each
3408 case, if a major error occurs (unless listed below) the
3409 actions are, in general, run backwards - this means that the
3410 maintainer scripts are run with different arguments in
3411 reverse order. These are the "error unwind" calls listed
3418 If a version of the package is already installed, call
3419 <example compact="compact">
3420 <var>old-prerm</var> upgrade <var>new-version</var>
3424 If the script runs but exits with a non-zero
3425 exit status, <prgn>dpkg</prgn> will attempt:
3426 <example compact="compact">
3427 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3429 Error unwind, for both the above cases:
3430 <example compact="compact">
3431 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3438 If a "conflicting" package is being removed at the same time:
3441 If any packages depended on that conflicting
3442 package and <tt>--auto-deconfigure</tt> is
3443 specified, call, for each such package:
3444 <example compact="compact">
3445 <var>deconfigured's-prerm</var> deconfigure \
3446 in-favour <var>package-being-installed</var> <var>version</var> \
3447 removing <var>conflicting-package</var> <var>version</var>
3450 <example compact="compact">
3451 <var>deconfigured's-postinst</var> abort-deconfigure \
3452 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3453 removing <var>conflicting-package</var> <var>version</var>
3455 The deconfigured packages are marked as
3456 requiring configuration, so that if
3457 <tt>--install</tt> is used they will be
3458 configured again if possible.
3461 To prepare for removal of the conflicting package, call:
3462 <example compact="compact">
3463 <var>conflictor's-prerm</var> remove \
3464 in-favour <var>package</var> <var>new-version</var>
3467 <example compact="compact">
3468 <var>conflictor's-postinst</var> abort-remove \
3469 in-favour <var>package</var> <var>new-version</var>
3478 If the package is being upgraded, call:
3479 <example compact="compact">
3480 <var>new-preinst</var> upgrade <var>old-version</var>
3484 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3486 If that too fails, then
3488 <var>old-postinst</var> abort-upgrade <var>old-version</var>
3493 Otherwise, if the package had some configuration
3494 files from a previous version installed (i.e., it
3495 is in the "configuration files only" state):
3496 <example compact="compact">
3497 <var>new-preinst</var> install <var>old-version</var>
3501 <var>new-postrm</var> abort-install <var>old-version</var>
3505 Otherwise (i.e., the package was completely purged):
3506 <example compact="compact">
3507 <var>new-preinst</var> install
3510 <example compact="compact">
3511 <var>new-postrm</var> abort-install
3519 The new package's files are unpacked, overwriting any
3520 that may be on the system already, for example any
3521 from the old version of the same package or from
3522 another package. Backups of the old files are kept
3523 temporarily, and if anything goes wrong the package
3524 management system will attempt to put them back as
3525 part of the error unwind.
3529 It is an error for a package to contain files which
3530 are on the system in another package, unless
3531 <tt>Replaces</tt> is used (see <ref id="replaces">).
3533 The following paragraph is not currently the case:
3534 Currently the <tt>- - force-overwrite</tt> flag is
3535 enabled, downgrading it to a warning, but this may not
3541 It is a more serious error for a package to contain a
3542 plain file or other kind of non-directory where another
3543 package has a directory (again, unless
3544 <tt>Replaces</tt> is used). This error can be
3545 overridden if desired using
3546 <tt>--force-overwrite-dir</tt>, but this is not
3551 Packages which overwrite each other's files produce
3552 behavior which, though deterministic, is hard for the
3553 system administrator to understand. It can easily
3554 lead to "missing" programs if, for example, a package
3555 is installed which overwrites a file from another
3556 package, and is then removed again.<footnote>
3557 Part of the problem is due to what is arguably a
3558 bug in <prgn>dpkg</prgn>.
3563 A directory will never be replaced by a symbolic link
3564 to a directory or vice versa; instead, the existing
3565 state (symlink or not) will be left alone and
3566 <prgn>dpkg</prgn> will follow the symlink if there is
3575 If the package is being upgraded, call
3576 <example compact="compact">
3577 <var>old-postrm</var> upgrade <var>new-version</var>
3581 If this fails, <prgn>dpkg</prgn> will attempt:
3582 <example compact="compact">
3583 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3585 Error unwind, for both cases:
3586 <example compact="compact">
3587 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3594 This is the point of no return - if
3595 <prgn>dpkg</prgn> gets this far, it won't back off
3596 past this point if an error occurs. This will
3597 leave the package in a fairly bad state, which
3598 will require a successful re-installation to clear
3599 up, but it's when <prgn>dpkg</prgn> starts doing
3600 things that are irreversible.
3605 Any files which were in the old version of the package
3606 but not in the new are removed.
3610 The new file list replaces the old.
3614 The new maintainer scripts replace the old.
3618 Any packages all of whose files have been overwritten
3619 during the installation, and which aren't required for
3620 dependencies, are considered to have been removed.
3621 For each such package
3624 <prgn>dpkg</prgn> calls:
3625 <example compact="compact">
3626 <var>disappearer's-postrm</var> disappear \
3627 <var>overwriter</var> <var>overwriter-version</var>
3631 The package's maintainer scripts are removed.
3634 It is noted in the status database as being in a
3635 sane state, namely not installed (any conffiles
3636 it may have are ignored, rather than being
3637 removed by <prgn>dpkg</prgn>). Note that
3638 disappearing packages do not have their prerm
3639 called, because <prgn>dpkg</prgn> doesn't know
3640 in advance that the package is going to
3647 Any files in the package we're unpacking that are also
3648 listed in the file lists of other packages are removed
3649 from those lists. (This will lobotomize the file list
3650 of the "conflicting" package if there is one.)
3654 The backup files made during installation, above, are
3660 The new package's status is now sane, and recorded as
3665 Here is another point of no return - if the
3666 conflicting package's removal fails we do not unwind
3667 the rest of the installation; the conflicting package
3668 is left in a half-removed limbo.
3673 If there was a conflicting package we go and do the
3674 removal actions (described below), starting with the
3675 removal of the conflicting package's files (any that
3676 are also in the package being installed have already
3677 been removed from the conflicting package's file list,
3678 and so do not get removed now).
3684 <sect id="configdetails"><heading>Details of configuration</heading>
3687 When we configure a package (this happens with <tt>dpkg
3688 --install</tt> and <tt>dpkg --configure</tt>), we first
3689 update any <tt>conffile</tt>s and then call:
3690 <example compact="compact">
3691 <var>postinst</var> configure <var>most-recently-configured-version</var>
3696 No attempt is made to unwind after errors during
3701 If there is no most recently configured version
3702 <prgn>dpkg</prgn> will pass a null argument.
3705 Historical note: Truly ancient (pre-1997) versions of
3706 <prgn>dpkg</prgn> passed <tt><unknown></tt>
3707 (including the angle brackets) in this case. Even older
3708 ones did not pass a second argument at all, under any
3709 circumstance. Note that upgrades using such an old dpkg
3710 version are unlikely to work for other reasons, even if
3711 this old argument behavior is handled by your postinst script.
3717 <sect id="removedetails"><heading>Details of removal and/or
3718 configuration purging</heading>
3723 <example compact="compact">
3724 <var>prerm</var> remove
3728 The package's files are removed (except <tt>conffile</tt>s).
3731 <example compact="compact">
3732 <var>postrm</var> remove
3737 All the maintainer scripts except the <prgn>postrm</prgn>
3742 If we aren't purging the package we stop here. Note
3743 that packages which have no <prgn>postrm</prgn> and no
3744 <tt>conffile</tt>s are automatically purged when
3745 removed, as there is no difference except for the
3746 <prgn>dpkg</prgn> status.
3750 The <tt>conffile</tt>s and any backup files
3751 (<tt>~</tt>-files, <tt>#*#</tt> files,
3752 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3756 <example compact="compact">
3757 <var>postrm</var> purge
3761 The package's file list is removed.
3765 If there are problems during this process, we call
3766 <example compact="compact">postinst
3767 abort-remove</example>. No other attempt is made to unwind
3768 after errors during removal.
3774 <chapt id="relationships">
3775 <heading>Declaring relationships between packages</heading>
3777 <sect id="depsyntax">
3778 <heading>Syntax of relationship fields</heading>
3781 These fields all have a uniform syntax. They are a list of
3782 package names separated by commas.
3786 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3787 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3788 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3789 control file fields of the package, which declare
3790 dependencies on other packages, the package names listed may
3791 also include lists of alternative package names, separated
3792 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3793 if any one of the alternative packages is installed, that
3794 part of the dependency is considered to be satisfied.
3798 All of the fields except for <tt>Provides</tt> may restrict
3799 their applicability to particular versions of each named
3800 package. This is done in parentheses after each individual
3801 package name; the parentheses should contain a relation from
3802 the list below followed by a version number, in the format
3803 described in <ref id="f-Version">.
3807 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3808 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3809 strictly earlier, earlier or equal, exactly equal, later or
3810 equal and strictly later, respectively. The deprecated
3811 forms <tt><</tt> and <tt>></tt> were used to mean
3812 earlier/later or equal, rather than strictly earlier/later,
3813 so they should not appear in new packages (though
3814 <prgn>dpkg</prgn> still supports them).
3818 Whitespace may appear at any point in the version
3819 specification subject to the rules in <ref
3820 id="controlsyntax">, and must appear where it's necessary to
3821 disambiguate; it is not otherwise significant. For
3822 consistency and in case of future changes to
3823 <prgn>dpkg</prgn> it is recommended that a single space be
3824 used after a version relationship and before a version
3825 number; it is also conventional to put a single space after
3826 each comma, on either side of each vertical bar, and before
3827 each open parenthesis.
3831 For example, a list of dependencies might appear as:
3832 <example compact="compact">
3835 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3840 All fields that specify build-time relationships
3841 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3842 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3843 may be restricted to a certain set of architectures. This
3844 is indicated in brackets after each individual package name and
3845 the optional version specification. The brackets enclose a
3846 list of Debian architecture names separated by whitespace.
3847 Exclamation marks may be prepended to each of the names.
3848 (It is not permitted for some names to be prepended with
3849 exclamation marks and others not.) If the current Debian
3850 host architecture is not in this list and there are no
3851 exclamation marks in the list, or it is in the list with a
3852 prepended exclamation mark, the package name and the
3853 associated version specification are ignored completely for
3854 the purposes of defining the relationships.
3859 <example compact="compact">
3861 Build-Depends-Indep: texinfo
3862 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3863 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3868 Note that the binary package relationship fields such as
3869 <tt>Depends</tt> appear in one of the binary package
3870 sections of the control file, whereas the build-time
3871 relationships such as <tt>Build-Depends</tt> appear in the
3872 source package section of the control file (which is the
3877 <sect id="binarydeps">
3878 <heading>Binary Dependencies - <tt>Depends</tt>,
3879 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3880 <tt>Pre-Depends</tt>
3884 Packages can declare in their control file that they have
3885 certain relationships to other packages - for example, that
3886 they may not be installed at the same time as certain other
3887 packages, and/or that they depend on the presence of others.
3891 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3892 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3893 <tt>Conflicts</tt> control file fields.
3897 These six fields are used to declare a dependency
3898 relationship by one package on another. Except for
3899 <tt>Enhances</tt>, they appear in the depending (binary)
3900 package's control file. (<tt>Enhances</tt> appears in the
3901 recommending package's control file.)
3905 A <tt>Depends</tt> field takes effect <em>only</em> when a
3906 package is to be configured. It does not prevent a package
3907 being on the system in an unconfigured state while its
3908 dependencies are unsatisfied, and it is possible to replace
3909 a package whose dependencies are satisfied and which is
3910 properly installed with a different version whose
3911 dependencies are not and cannot be satisfied; when this is
3912 done the depending package will be left unconfigured (since
3913 attempts to configure it will give errors) and will not
3914 function properly. If it is necessary, a
3915 <tt>Pre-Depends</tt> field can be used, which has a partial
3916 effect even when a package is being unpacked, as explained
3917 in detail below. (The other three dependency fields,
3918 <tt>Recommends</tt>, <tt>Suggests</tt> and
3919 <tt>Enhances</tt>, are only used by the various front-ends
3920 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3924 For this reason packages in an installation run are usually
3925 all unpacked first and all configured later; this gives
3926 later versions of packages with dependencies on later
3927 versions of other packages the opportunity to have their
3928 dependencies satisfied.
3932 The <tt>Depends</tt> field thus allows package maintainers
3933 to impose an order in which packages should be configured.
3937 The meaning of the five dependency fields is as follows:
3939 <tag><tt>Depends</tt></tag>
3942 This declares an absolute dependency. A package will
3943 not be configured unless all of the packages listed in
3944 its <tt>Depends</tt> field have been correctly
3949 The <tt>Depends</tt> field should be used if the
3950 depended-on package is required for the depending
3951 package to provide a significant amount of
3956 The <tt>Depends</tt> field should also be used if the
3957 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3958 <prgn>postrm</prgn> scripts require the package to be
3959 present in order to run. Note, however, that the
3960 <prgn>postrm</prgn> cannot rely on any non-essential
3961 packages to be present during the <tt>purge</tt>
3965 <tag><tt>Recommends</tt></tag>
3968 This declares a strong, but not absolute, dependency.
3972 The <tt>Recommends</tt> field should list packages
3973 that would be found together with this one in all but
3974 unusual installations.
3978 <tag><tt>Suggests</tt></tag>
3980 This is used to declare that one package may be more
3981 useful with one or more others. Using this field
3982 tells the packaging system and the user that the
3983 listed packages are related to this one and can
3984 perhaps enhance its usefulness, but that installing
3985 this one without them is perfectly reasonable.
3988 <tag><tt>Enhances</tt></tag>
3990 This field is similar to Suggests but works in the
3991 opposite direction. It is used to declare that a
3992 package can enhance the functionality of another
3996 <tag><tt>Pre-Depends</tt></tag>
3999 This field is like <tt>Depends</tt>, except that it
4000 also forces <prgn>dpkg</prgn> to complete installation
4001 of the packages named before even starting the
4002 installation of the package which declares the
4003 pre-dependency, as follows:
4007 When a package declaring a pre-dependency is about to
4008 be <em>unpacked</em> the pre-dependency can be
4009 satisfied if the depended-on package is either fully
4010 configured, <em>or even if</em> the depended-on
4011 package(s) are only unpacked or half-configured,
4012 provided that they have been configured correctly at
4013 some point in the past (and not removed or partially
4014 removed since). In this case, both the
4015 previously-configured and currently unpacked or
4016 half-configured versions must satisfy any version
4017 clause in the <tt>Pre-Depends</tt> field.
4021 When the package declaring a pre-dependency is about
4022 to be <em>configured</em>, the pre-dependency will be
4023 treated as a normal <tt>Depends</tt>, that is, it will
4024 be considered satisfied only if the depended-on
4025 package has been correctly configured.
4029 <tt>Pre-Depends</tt> should be used sparingly,
4030 preferably only by packages whose premature upgrade or
4031 installation would hamper the ability of the system to
4032 continue with any upgrade that might be in progress.
4036 <tt>Pre-Depends</tt> are also required if the
4037 <prgn>preinst</prgn> script depends on the named
4038 package. It is best to avoid this situation if
4046 When selecting which level of dependency to use you should
4047 consider how important the depended-on package is to the
4048 functionality of the one declaring the dependency. Some
4049 packages are composed of components of varying degrees of
4050 importance. Such a package should list using
4051 <tt>Depends</tt> the package(s) which are required by the
4052 more important components. The other components'
4053 requirements may be mentioned as Suggestions or
4054 Recommendations, as appropriate to the components' relative
4059 <sect id="conflicts">
4060 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4063 When one binary package declares a conflict with another
4064 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4065 refuse to allow them to be installed on the system at the
4070 If one package is to be installed, the other must be removed
4071 first - if the package being installed is marked as
4072 replacing (see <ref id="replaces">) the one on the system,
4073 or the one on the system is marked as deselected, or both
4074 packages are marked <tt>Essential</tt>, then
4075 <prgn>dpkg</prgn> will automatically remove the package
4076 which is causing the conflict, otherwise it will halt the
4077 installation of the new package with an error. This
4078 mechanism is specifically designed to produce an error when
4079 the installed package is <tt>Essential</tt>, but the new
4084 A package will not cause a conflict merely because its
4085 configuration files are still installed; it must be at least
4090 A special exception is made for packages which declare a
4091 conflict with their own package name, or with a virtual
4092 package which they provide (see below): this does not
4093 prevent their installation, and allows a package to conflict
4094 with others providing a replacement for it. You use this
4095 feature when you want the package in question to be the only
4096 package providing some feature.
4100 A <tt>Conflicts</tt> entry should almost never have an
4101 "earlier than" version clause. This would prevent
4102 <prgn>dpkg</prgn> from upgrading or installing the package
4103 which declared such a conflict until the upgrade or removal
4104 of the conflicted-with package had been completed.
4108 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4112 As well as the names of actual ("concrete") packages, the
4113 package relationship fields <tt>Depends</tt>,
4114 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4115 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4116 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4117 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4118 may mention "virtual packages".
4122 A <em>virtual package</em> is one which appears in the
4123 <tt>Provides</tt> control file field of another package.
4124 The effect is as if the package(s) which provide a
4125 particular virtual package name had been listed by name
4126 everywhere the virtual package name appears. (See also <ref
4131 If there are both concrete and virtual packages of the same
4132 name, then the dependency may be satisfied (or the conflict
4133 caused) by either the concrete package with the name in
4134 question or any other concrete package which provides the
4135 virtual package with the name in question. This is so that,
4136 for example, supposing we have
4137 <example compact="compact">
4141 and someone else releases an enhanced version of the
4142 <tt>bar</tt> package (for example, a non-US variant), they
4144 <example compact="compact">
4148 and the <tt>bar-plus</tt> package will now also satisfy the
4149 dependency for the <tt>foo</tt> package.
4153 If a dependency or a conflict has a version number attached
4154 then only real packages will be considered to see whether
4155 the relationship is satisfied (or the prohibition violated,
4156 for a conflict) - it is assumed that a real package which
4157 provides the virtual package is not of the "right" version.
4158 So, a <tt>Provides</tt> field may not contain version
4159 numbers, and the version number of the concrete package
4160 which provides a particular virtual package will not be
4161 looked at when considering a dependency on or conflict with
4162 the virtual package name.
4166 It is likely that the ability will be added in a future
4167 release of <prgn>dpkg</prgn> to specify a version number for
4168 each virtual package it provides. This feature is not yet
4169 present, however, and is expected to be used only
4174 If you want to specify which of a set of real packages
4175 should be the default to satisfy a particular dependency on
4176 a virtual package, you should list the real package as an
4177 alternative before the virtual one.
4182 <sect id="replaces"><heading>Overwriting files and replacing
4183 packages - <tt>Replaces</tt></heading>
4186 Packages can declare in their control file that they should
4187 overwrite files in certain other packages, or completely
4188 replace other packages. The <tt>Replaces</tt> control file
4189 field has these two distinct purposes.
4192 <sect1><heading>Overwriting files in other packages</heading>
4195 Firstly, as mentioned before, it is usually an error for a
4196 package to contain files which are on the system in
4201 However, if the overwriting package declares that it
4202 <tt>Replaces</tt> the one containing the file being
4203 overwritten, then <prgn>dpkg</prgn> will replace the file
4204 from the old package with that from the new. The file
4205 will no longer be listed as "owned" by the old package.
4209 If a package is completely replaced in this way, so that
4210 <prgn>dpkg</prgn> does not know of any files it still
4211 contains, it is considered to have "disappeared". It will
4212 be marked as not wanted on the system (selected for
4213 removal) and not installed. Any <tt>conffile</tt>s
4214 details noted for the package will be ignored, as they
4215 will have been taken over by the overwriting package. The
4216 package's <prgn>postrm</prgn> script will be run with a
4217 special argument to allow the package to do any final
4218 cleanup required. See <ref id="mscriptsinstact">.
4221 Replaces is a one way relationship -- you have to
4222 install the replacing package after the replaced
4229 For this usage of <tt>Replaces</tt>, virtual packages (see
4230 <ref id="virtual">) are not considered when looking at a
4231 <tt>Replaces</tt> field - the packages declared as being
4232 replaced must be mentioned by their real names.
4236 Furthermore, this usage of <tt>Replaces</tt> only takes
4237 effect when both packages are at least partially on the
4238 system at once, so that it can only happen if they do not
4239 conflict or if the conflict has been overridden.
4244 <sect1><heading>Replacing whole packages, forcing their
4248 Secondly, <tt>Replaces</tt> allows the packaging system to
4249 resolve which package should be removed when there is a
4250 conflict - see <ref id="conflicts">. This usage only
4251 takes effect when the two packages <em>do</em> conflict,
4252 so that the two usages of this field do not interfere with
4257 In this situation, the package declared as being replaced
4258 can be a virtual package, so for example, all mail
4259 transport agents (MTAs) would have the following fields in
4260 their control files:
4261 <example compact="compact">
4262 Provides: mail-transport-agent
4263 Conflicts: mail-transport-agent
4264 Replaces: mail-transport-agent
4266 ensuring that only one MTA can be installed at any one
4271 <sect id="sourcebinarydeps">
4272 <heading>Relationships between source and binary packages -
4273 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4274 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4278 Source packages that require certain binary packages to be
4279 installed or absent at the time of building the package
4280 can declare relationships to those binary packages.
4284 This is done using the <tt>Build-Depends</tt>,
4285 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4286 <tt>Build-Conflicts-Indep</tt> control file fields.
4290 Build-dependencies on "build-essential" binary packages can be
4291 omitted. Please see <ref id="pkg-relations"> for more information.
4295 The dependencies and conflicts they define must be satisfied
4296 (as defined earlier for binary packages) in order to invoke
4297 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4299 If you make "build-arch" or "binary-arch", you need
4300 Build-Depends. If you make "build-indep" or
4301 "binary-indep", you need Build-Depends and
4302 Build-Depends-Indep. If you make "build" or "binary",
4306 There is no Build-Depends-Arch; the autobuilders will
4307 only need the Build-Depends if they know how to build
4308 only build-arch and binary-arch. Anyone building the
4309 build-indep/binary-indep targets is basically assumed to
4310 be building the whole package and so installs all build
4314 The purpose of the original split, I recall, was so that
4315 the autobuilders wouldn't need to install extra packages
4316 needed only for the binary-indep targets. But without a
4317 build-arch/build-indep split, this didn't work, since
4318 most of the work is done in the build target, not in the
4324 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4326 The <tt>Build-Depends</tt> and
4327 <tt>Build-Conflicts</tt> fields must be satisfied when
4328 any of the following targets is invoked:
4329 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4330 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4331 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4333 <tag><tt>Build-Depends-Indep</tt>,
4334 <tt>Build-Conflicts-Indep</tt></tag>
4336 The <tt>Build-Depends-Indep</tt> and
4337 <tt>Build-Conflicts-Indep</tt> fields must be
4338 satisfied when any of the following targets is
4339 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4340 <tt>binary</tt> and <tt>binary-indep</tt>.
4350 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4353 Packages containing shared libraries must be constructed with
4354 a little care to make sure that the shared library is always
4355 available. This is especially important for packages whose
4356 shared libraries are vitally important, such as the C library
4357 (currently <tt>libc6</tt>).
4361 Packages involving shared libraries should be split up into
4362 several binary packages. This section mostly deals with how
4363 this separation is to be accomplished; rules for files within
4364 the shared library packages are in <ref id="libraries"> instead.
4367 <sect id="sharedlibs-runtime">
4368 <heading>Run-time shared libraries</heading>
4371 The run-time shared library needs to be placed in a package
4372 whose name changes whenever the shared object version
4375 Since it is common place to install several versions of a
4376 package that just provides shared libraries, it is a
4377 good idea that that the library package should not
4378 contain any extraneous non-versioned files, unless they
4379 happen to be in versioned directories.</p>
4381 The most common mechanism is to place it in a package
4383 <package><var>libraryname</var><var>soversion</var></package>,
4384 where <file><var>soversion</var></file> is the version number
4385 in the soname of the shared library<footnote>
4386 The soname is the shared object name: it's the thing
4387 that has to match exactly between building an executable
4388 and running it for the dynamic linker to be able run the
4389 program. For example, if the soname of the library is
4390 <file>libfoo.so.6</file>, the library package would be
4391 called <file>libfoo6</file>.
4393 Alternatively, if it would be confusing to directly append
4394 <var>soversion</var> to <var>libraryname</var> (e.g. because
4395 <var>libraryname</var> itself ends in a number), you may use
4396 <package><var>libraryname</var>-<var>soversion</var></package> and
4397 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4402 If your package includes run-time support programs that
4403 do not need to be invoked manually by users, but are
4404 nevertheless required for the package to function, then it
4405 is recommended that these programs are placed
4406 (if they are binary) in a subdirectory of
4407 <file>/usr/lib</file>, preferably under
4408 <file>/usr/lib/</file><var>package-name</var>.
4409 If the program is architecture independent, the
4410 recommendation is for it to be placed in a subdirectory of
4411 <file>/usr/share</file> instead, preferably under
4412 <file>/usr/share/</file><var>package-name</var>.
4417 If you have several shared libraries built from the same
4418 source tree you may lump them all together into a single
4419 shared library package, provided that you change all of
4420 their sonames at once (so that you don't get filename
4421 clashes if you try to install different versions of the
4422 combined shared libraries package).
4426 The package should install the shared libraries under
4427 their normal names. For example, the <package>libgdbm3</package>
4428 package should install <file>libgdbm.so.3.0.0</file> as
4429 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4430 renamed or re-linked by any <prgn>prerm</prgn> or
4431 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4432 of renaming things safely without affecting running programs,
4433 and attempts to interfere with this are likely to lead to
4438 Shared libraries should not be installed executable, since
4439 the dynamic linker does not require this and trying to
4440 execute a shared library usually results in a core dump.
4444 The run-time library package should include the symbolic link that
4445 <prgn>ldconfig</prgn> would create for the shared libraries.
4446 For example, the <package>libgdbm3</package> package should include
4447 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4448 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4449 linker (for example <prgn>ld.so</prgn> or
4450 <prgn>ld-linux.so.*</prgn>) can find the library between the
4451 time that <prgn>dpkg</prgn> installs it and the time that
4452 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4454 The package management system requires the library to be
4455 placed before the symbolic link pointing to it in the
4456 <file>.deb</file> file. This is so that when
4457 <prgn>dpkg</prgn> comes to install the symlink
4458 (overwriting the previous symlink pointing at an older
4459 version of the library), the new shared library is already
4460 in place. In the past, this was achieved by creating the
4461 library in the temporary packaging directory before
4462 creating the symlink. Unfortunately, this was not always
4463 effective, since the building of the tar file in the
4464 <file>.deb</file> depended on the behavior of the underlying
4465 file system. Some file systems (such as reiserfs) reorder
4466 the files so that the order of creation is forgotten.
4467 Since version 1.7.0, <prgn>dpkg</prgn>
4468 reorders the files itself as necessary when building a
4469 package. Thus it is no longer important to concern
4470 oneself with the order of file creation.
4474 <sect1 id="ldconfig">
4475 <heading><tt>ldconfig</tt></heading>
4478 Any package installing shared libraries in one of the default
4479 library directories of the dynamic linker (which are currently
4480 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4481 listed in <file>/etc/ld.so.conf</file><footnote>
4483 <list compact="compact">
4484 <item>/usr/X11R6/lib/Xaw3d</item>
4485 <item>/usr/local/lib</item>
4486 <item>/usr/lib/libc5-compat</item>
4487 <item>/lib/libc5-compat</item>
4488 <item>/usr/X11R6/lib</item>
4491 must use <prgn>ldconfig</prgn> to update the shared library
4496 The package must call <prgn>ldconfig</prgn> in the
4497 <prgn>postinst</prgn> script if the first argument is
4498 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4499 optionally invoke <prgn>ldconfig</prgn> at other times. The
4500 package should call <prgn>ldconfig</prgn> in the
4501 <prgn>postrm</prgn> script if the first argument is
4502 <tt>remove</tt>. The maintainer scripts must not invoke
4503 <prgn>ldconfig</prgn> under any circumstances other than those
4504 described in this paragraph.<footnote>
4506 During install or upgrade, the preinst is called before
4507 the new files are installed, so calling "ldconfig" is
4508 pointless. The preinst of an existing package can also be
4509 called if an upgrade fails. However, this happens during
4510 the critical time when a shared libs may exist on-disk
4511 under a temporary name. Thus, it is dangerous and
4512 forbidden by current policy to call "ldconfig" at this
4517 When a package is installed or upgraded, "postinst
4518 configure" runs after the new files are safely on-disk.
4519 Since it is perfectly safe to invoke ldconfig
4520 unconditionally in a postinst, it is OK for a package to
4521 simply put ldconfig in its postinst without checking the
4522 argument. The postinst can also be called to recover from
4523 a failed upgrade. This happens before any new files are
4524 unpacked, so there is no reason to call "ldconfig" at this
4529 For a package that is being removed, prerm is
4530 called with all the files intact, so calling ldconfig is
4531 useless. The other calls to "prerm" happen in the case of
4532 upgrade at a time when all the files of the old package
4533 are on-disk, so again calling "ldconfig" is pointless.
4537 postrm, on the other hand, is called with the "remove"
4538 argument just after the files are removed, so this is the
4539 proper time to call "ldconfig" to notify the system of the
4540 fact shared libraries from the package are removed.
4541 The postrm can be called at several other times. At the
4542 time of "postrm purge", "postrm abort-install", or "postrm
4543 abort-upgrade", calling "ldconfig" is useless because the
4544 shared lib files are not on-disk. However, when "postrm"
4545 is invoked with arguments "upgrade", "failed-upgrade", or
4546 "disappear", a shared lib may exist on-disk under a
4555 <sect id="sharedlibs-runtime-progs">
4556 <heading>Run-time support programs</heading>
4559 If your package has some run-time support programs which use
4560 the shared library you must not put them in the shared
4561 library package. If you do that then you won't be able to
4562 install several versions of the shared library without
4563 getting filename clashes.
4567 Instead, either create another package for the runtime binaries
4568 (this package might typically be named
4569 <package><var>libraryname</var>-runtime</package>; note the absence
4570 of the <var>soversion</var> in the package name), or if the
4571 development package is small, include them in there.
4575 <sect id="sharedlibs-static">
4576 <heading>Static libraries</heading>
4579 The static library (<file><var>libraryname.a</var></file>)
4580 is usually provided in addition to the shared version.
4581 It is placed into the development package (see below).
4585 In some cases, it is acceptable for a library to be
4586 available in static form only; these cases include:
4588 <item>libraries for languages whose shared library support
4589 is immature or unstable</item>
4590 <item>libraries whose interfaces are in flux or under
4591 development (commonly the case when the library's
4592 major version number is zero, or where the ABI breaks
4593 across patchlevels)</item>
4594 <item>libraries which are explicitly intended to be
4595 available only in static form by their upstream
4600 <sect id="sharedlibs-dev">
4601 <heading>Development files</heading>
4604 The development files associated to a shared library need to be
4605 placed in a package called
4606 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4607 or if you prefer only to support one development version at a
4608 time, <package><var>libraryname</var>-dev</package>.
4612 In case several development versions of a library exist, you may
4613 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4614 <ref id="conflicts">) to ensure that the user only installs one
4615 development version at a time (as different development versions are
4616 likely to have the same header files in them, which would cause a
4617 filename clash if both were installed).
4621 The development package should contain a symlink for the associated
4622 shared library without a version number. For example, the
4623 <package>libgdbm-dev</package> package should include a symlink
4624 from <file>/usr/lib/libgdbm.so</file> to
4625 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
4626 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4627 <file>libgdbm.so</file> when compiling dynamically.
4631 <sect id="sharedlibs-intradeps">
4632 <heading>Dependencies between the packages of the same library</heading>
4635 Typically the development version should have an exact
4636 version dependency on the runtime library, to make sure that
4637 compilation and linking happens correctly. The
4638 <tt>${Source-Version}</tt> substitution variable can be
4639 useful for this purpose.
4643 <sect id="sharedlibs-shlibdeps">
4644 <heading>Dependencies between the library and other packages -
4645 the <tt>shlibs</tt> system</heading>
4648 If a package contains a binary or library which links to a
4649 shared library, we must ensure that when the package is
4650 installed on the system, all of the libraries needed are
4651 also installed. This requirement led to the creation of the
4652 <tt>shlibs</tt> system, which is very simple in its design:
4653 any package which <em>provides</em> a shared library also
4654 provides information on the package dependencies required to
4655 ensure the presence of this library, and any package which
4656 <em>uses</em> a shared library uses this information to
4657 determine the dependencies it requires. The files which
4658 contain the mapping from shared libraries to the necessary
4659 dependency information are called <file>shlibs</file> files.
4663 Thus, when a package is built which contains any shared
4664 libraries, it must provide a <file>shlibs</file> file for other
4665 packages to use, and when a package is built which contains
4666 any shared libraries or compiled binaries, it must run
4667 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4668 on these to determine the libraries used and hence the
4669 dependencies needed by this package.<footnote>
4671 In the past, the shared libraries linked to were
4672 determined by calling <prgn>ldd</prgn>, but now
4673 <prgn>objdump</prgn> is used to do this. The only
4674 change this makes to package building is that
4675 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4676 libraries, whereas in the past this was unnecessary.
4677 The rest of this footnote explains the advantage that
4682 We say that a binary <tt>foo</tt> <em>directly</em> uses
4683 a library <tt>libbar</tt> if it is explicitly linked
4684 with that library (that is, it uses the flag
4685 <tt>-lbar</tt> during the linking stage). Other
4686 libraries that are needed by <tt>libbar</tt> are linked
4687 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4688 linker will load them automatically when it loads
4689 <tt>libbar</tt>. A package should depend on
4690 the libraries it directly uses, and the dependencies for
4691 those libraries should automatically pull in the other
4696 Unfortunately, the <prgn>ldd</prgn> program shows both
4697 the directly and indirectly used libraries, meaning that
4698 the dependencies determined included both direct and
4699 indirect dependencies. The use of <prgn>objdump</prgn>
4700 avoids this problem by determining only the directly
4705 A good example of where this helps is the following. We
4706 could update <tt>libimlib</tt> with a new version that
4707 supports a new graphics format called dgf (but retaining
4708 the same major version number). If we used the old
4709 <prgn>ldd</prgn> method, every package that uses
4710 <tt>libimlib</tt> would need to be recompiled so it
4711 would also depend on <tt>libdgf</tt> or it wouldn't run
4712 due to missing symbols. However with the new system,
4713 packages using <tt>libimlib</tt> can rely on
4714 <tt>libimlib</tt> itself having the dependency on
4715 <tt>libdgf</tt> and so they would not need rebuilding.
4721 In the following sections, we will first describe where the
4722 various <tt>shlibs</tt> files are to be found, then how to
4723 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
4724 file format and how to create them if your package contains a
4729 <heading>The <tt>shlibs</tt> files present on the system</heading>
4732 There are several places where <tt>shlibs</tt> files are
4733 found. The following list gives them in the order in which
4735 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
4736 (The first one which gives the required information is used.)
4742 <p><file>debian/shlibs.local</file></p>
4745 This lists overrides for this package. Its use is
4746 described below (see <ref id="shlibslocal">).
4751 <p><file>/etc/dpkg/shlibs.override</file></p>
4754 This lists global overrides. This list is normally
4755 empty. It is maintained by the local system
4761 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4764 When packages are being built, any
4765 <file>debian/shlibs</file> files are copied into the
4766 control file area of the temporary build directory and
4767 given the name <file>shlibs</file>. These files give
4768 details of any shared libraries included in the
4770 An example may help here. Let us say that the
4771 source package <tt>foo</tt> generates two binary
4772 packages, <tt>libfoo2</tt> and
4773 <tt>foo-runtime</tt>. When building the binary
4774 packages, the two packages are created in the
4775 directories <file>debian/libfoo2</file> and
4776 <file>debian/foo-runtime</file> respectively.
4777 (<file>debian/tmp</file> could be used instead of one
4778 of these.) Since <tt>libfoo2</tt> provides the
4779 <tt>libfoo</tt> shared library, it will require a
4780 <tt>shlibs</tt> file, which will be installed in
4781 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4783 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4784 when <prgn>dpkg-shlibdeps</prgn> is run on the
4786 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4788 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4789 determine whether <tt>foo-prog</tt>'s library
4790 dependencies are satisfied by any of the libraries
4791 provided by <tt>libfoo2</tt>. For this reason,
4792 <prgn>dpkg-shlibdeps</prgn> must only be run once
4793 all of the individual binary packages'
4794 <tt>shlibs</tt> files have been installed into the
4801 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4804 These are the <file>shlibs</file> files corresponding to
4805 all of the packages installed on the system, and are
4806 maintained by the relevant package maintainers.
4811 <p><file>/etc/dpkg/shlibs.default</file></p>
4814 This file lists any shared libraries whose packages
4815 have failed to provide correct <file>shlibs</file> files.
4816 It was used when the <file>shlibs</file> setup was first
4817 introduced, but it is now normally empty. It is
4818 maintained by the <tt>dpkg</tt> maintainer.
4826 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4827 <file>shlibs</file> files</heading>
4831 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
4832 into your <file>debian/rules</file> file. If your package
4833 contains only compiled binaries and libraries (but no scripts),
4834 you can use a command such as:
4835 <example compact="compact">
4836 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4837 debian/tmp/usr/lib/*
4839 Otherwise, you will need to explicitly list the compiled
4840 binaries and libraries.<footnote>
4841 If you are using <tt>debhelper</tt>, the
4842 <prgn>dh_shlibdeps</prgn> program will do this work for
4843 you. It will also correctly handle multi-binary
4849 This command puts the dependency information into the
4850 <file>debian/substvars</file> file, which is then used by
4851 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4852 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4853 field in the control file for this to work.
4857 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4858 done. If it does complain you might need to create your own
4859 <file>debian/shlibs.local</file> file, as explained below (see
4860 <ref id="shlibslocal">).
4864 If you have multiple binary packages, you will need to call
4865 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4866 compiled libraries or binaries. In such a case, you will
4867 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4868 utilities to specify a different <file>substvars</file> file.
4872 For more details on dpkg-shlibdeps, please see
4873 <ref id="pkg-dpkg-shlibdeps"> and
4874 <manref name="dpkg-shlibdeps" section="1">.
4879 <heading>The <file>shlibs</file> File Format</heading>
4882 Each <file>shlibs</file> file has the same format. Lines
4883 beginning with <tt>#</tt> are considered to be comments and
4884 are ignored. Each line is of the form:
4885 <example compact="compact">
4886 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4891 We will explain this by reference to the example of the
4892 <tt>zlib1g</tt> package, which (at the time of writing)
4893 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4897 <var>library-name</var> is the name of the shared library,
4898 in this case <tt>libz</tt>. (This must match the name part
4899 of the soname, see below.)
4903 <var>soname-version-number</var> is the version part of the
4904 soname of the library. The soname is the thing that must
4905 exactly match for the library to be recognized by the
4906 dynamic linker, and is usually of the form
4907 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4908 example, <tt>libz.so.1</tt>.<footnote>
4909 This can be determined using the command
4910 <example compact="compact">
4911 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4914 The version part is the part which comes after
4915 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4919 <var>dependencies</var> has the same syntax as a dependency
4920 field in a binary package control file. It should give
4921 details of which packages are required to satisfy a binary
4922 built against the version of the library contained in the
4923 package. See <ref id="depsyntax"> for details.
4927 In our example, if the first version of the <tt>zlib1g</tt>
4928 package which contained a minor number of at least
4929 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4930 <tt>shlibs</tt> entry for this library could say:
4931 <example compact="compact">
4932 libz 1 zlib1g (>= 1:1.1.3)
4934 The version-specific dependency is to avoid warnings from
4935 the dynamic linker about using older shared libraries with
4941 <heading>Providing a <file>shlibs</file> file</heading>
4944 If your package provides a shared library, you should create
4945 a <file>shlibs</file> file following the format described above.
4946 It is usual to call this file <file>debian/shlibs</file> (but if
4947 you have multiple binary packages, you might want to call it
4948 <file>debian/shlibs.<var>package</var></file> instead). Then
4949 let <file>debian/rules</file> install it in the control area:
4950 <example compact="compact">
4951 install -m644 debian/shlibs debian/tmp/DEBIAN
4953 or, in the case of a multi-binary package:
4954 <example compact="compact">
4955 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4957 An alternative way of doing this is to create the
4958 <file>shlibs</file> file in the control area directly from
4959 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4960 file at all,<footnote>
4961 This is what <prgn>dh_makeshlibs</prgn> in the
4962 <tt>debhelper</tt> suite does.
4964 since the <file>debian/shlibs</file> file itself is ignored by
4965 <prgn>dpkg-shlibdeps</prgn>.
4969 As <prgn>dpkg-shlibdeps</prgn> reads the
4970 <file>DEBIAN/shlibs</file> files in all of the binary packages
4971 being built from this source package, all of the
4972 <file>DEBIAN/shlibs</file> files should be installed before
4973 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4978 <sect1 id="shlibslocal">
4979 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4982 This file is intended only as a <em>temporary</em> fix if
4983 your binaries or libraries depend on a library whose package
4984 does not yet provide a correct <file>shlibs</file> file.
4988 We will assume that you are trying to package a binary
4989 <tt>foo</tt>. When you try running
4990 <prgn>dpkg-shlibdeps</prgn> you get the following error
4991 message (<tt>-O</tt> displays the dependency information on
4992 <tt>stdout</tt> instead of writing it to
4993 <tt>debian/substvars</tt>, and the lines have been wrapped
4994 for ease of reading):
4995 <example compact="compact">
4996 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4997 dpkg-shlibdeps: warning: unable to find dependency
4998 information for shared library libbar (soname 1,
4999 path /usr/lib/libbar.so.1, dependency field Depends)
5000 shlibs:Depends=libc6 (>= 2.2.2-2)
5002 You can then run <prgn>ldd</prgn> on the binary to find the
5003 full location of the library concerned:
5004 <example compact="compact">
5006 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5007 libc.so.6 => /lib/libc.so.6 (0x40032000)
5008 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5010 So the <prgn>foo</prgn> binary depends on the
5011 <prgn>libbar</prgn> shared library, but no package seems to
5012 provide a <file>*.shlibs</file> file handling
5013 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5014 determine the package responsible:
5015 <example compact="compact">
5016 $ dpkg -S /usr/lib/libbar.so.1
5017 bar1: /usr/lib/libbar.so.1
5018 $ dpkg -s bar1 | grep Version
5021 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5022 is the one we are using. Now we can file a bug against the
5023 <tt>bar1</tt> package and create our own
5024 <file>debian/shlibs.local</file> to locally fix the problem.
5025 Including the following line into your
5026 <file>debian/shlibs.local</file> file:
5027 <example compact="compact">
5028 libbar 1 bar1 (>= 1.0-1)
5030 should allow the package build to work.
5034 As soon as the maintainer of <tt>bar1</tt> provides a
5035 correct <file>shlibs</file> file, you should remove this line
5036 from your <file>debian/shlibs.local</file> file. (You should
5037 probably also then have a versioned <tt>Build-Depends</tt>
5038 on <tt>bar1</tt> to help ensure that others do not have the
5039 same problem building your package.)
5048 <chapt id="opersys"><heading>The Operating System</heading>
5051 <heading>Filesystem hierarchy</heading>
5055 <heading>Filesystem Structure</heading>
5058 The location of all installed files and directories must
5059 comply with the Filesystem Hierarchy Standard (FHS),
5060 version 2.1, except where doing so would violate other
5061 terms of Debian Policy. The version of this document
5062 referred here can be found in the <tt>debian-policy</tt>
5064 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5065 name="FHS (Debian copy)"> alongside this manual (or, if
5066 you have the <package>debian-policy</package> installed,
5068 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5069 (local copy)">). The
5070 latest version, which may be a more recent version, may
5072 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5073 Specific questions about following the standard may be
5074 asked on the <tt>debian-devel</tt> mailing list, or
5075 referred to the FHS mailing list (see the
5076 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5082 <heading>Site-specific programs</heading>
5085 As mandated by the FHS, packages must not place any
5086 files in <file>/usr/local</file>, either by putting them in
5087 the file system archive to be unpacked by <prgn>dpkg</prgn>
5088 or by manipulating them in their maintainer scripts.
5092 However, the package may create empty directories below
5093 <file>/usr/local</file> so that the system administrator knows
5094 where to place site-specific files. These directories
5095 should be removed on package removal if they are
5100 Note, that this applies only to directories <em>below</em>
5101 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5102 Packages must not create sub-directories in the directory
5103 <file>/usr/local</file> itself, except those listed in FHS,
5104 section 4.5. However, you may create directories below
5105 them as you wish. You must not remove any of the
5106 directories listed in 4.5, even if you created them.
5110 Since <file>/usr/local</file> can be mounted read-only from a
5111 remote server, these directories must be created and
5112 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5113 maintainer scripts and not be included in the
5114 <file>.deb</file> archive. These scripts must not fail if
5115 either of these operations fail.
5119 For example, the <tt>emacsen-common</tt> package could
5120 contain something like
5121 <example compact="compact">
5122 if [ ! -e /usr/local/share/emacs ]
5124 if mkdir /usr/local/share/emacs 2>/dev/null
5126 chown root:staff /usr/local/share/emacs
5127 chmod 2775 /usr/local/share/emacs
5131 in its <prgn>postinst</prgn> script, and
5132 <example compact="compact">
5133 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5134 rmdir /usr/local/share/emacs 2>/dev/null || true
5136 in the <prgn>prerm</prgn> script. (Note that this form is
5137 used to ensure that if the script is interrupted, the
5138 directory <file>/usr/local/share/emacs</file> will still be
5143 If you do create a directory in <file>/usr/local</file> for
5144 local additions to a package, you should ensure that
5145 settings in <file>/usr/local</file> take precedence over the
5146 equivalents in <file>/usr</file>.
5150 However, because <file>/usr/local</file> and its contents are
5151 for exclusive use of the local administrator, a package
5152 must not rely on the presence or absence of files or
5153 directories in <file>/usr/local</file> for normal operation.
5157 The <file>/usr/local</file> directory itself and all the
5158 subdirectories created by the package should (by default) have
5159 permissions 2775 (group-writable and set-group-id) and be
5160 owned by <tt>root.staff</tt>.
5165 <heading>The system-wide mail directory</heading>
5167 The system-wide mail directory is <file>/var/mail</file>. This
5168 directory is part of the base system and should not owned
5169 by any particular mail agents. The use of the old
5170 location <file>/var/spool/mail</file> is deprecated, even
5171 though the spool may still be physically located there.
5172 To maintain partial upgrade compatibility for systems
5173 which have <file>/var/spool/mail</file> as their physical mail
5174 spool, packages using <file>/var/mail</file> must depend on
5175 either <package>libc6</package> (>= 2.1.3-13), or on
5176 <package>base-files</package> (>= 2.2.0), or on later
5177 versions of either one of these packages.
5183 <heading>Users and groups</heading>
5186 <heading>Introduction</heading>
5188 The Debian system can be configured to use either plain or
5193 Some user ids (UIDs) and group ids (GIDs) are reserved
5194 globally for use by certain packages. Because some
5195 packages need to include files which are owned by these
5196 users or groups, or need the ids compiled into binaries,
5197 these ids must be used on any Debian system only for the
5198 purpose for which they are allocated. This is a serious
5199 restriction, and we should avoid getting in the way of
5200 local administration policies. In particular, many sites
5201 allocate users and/or local system groups starting at 100.
5205 Apart from this we should have dynamically allocated ids,
5206 which should by default be arranged in some sensible
5207 order, but the behavior should be configurable.
5211 Packages other than <tt>base-passwd</tt> must not modify
5212 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5213 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5218 <heading>UID and GID classes</heading>
5220 The UID and GID numbers are divided into classes as
5226 Globally allocated by the Debian project, the same
5227 on every Debian system. These ids will appear in
5228 the <file>passwd</file> and <file>group</file> files of all
5229 Debian systems, new ids in this range being added
5230 automatically as the <tt>base-passwd</tt> package is
5235 Packages which need a single statically allocated
5236 uid or gid should use one of these; their
5237 maintainers should ask the <tt>base-passwd</tt>
5245 Dynamically allocated system users and groups.
5246 Packages which need a user or group, but can have
5247 this user or group allocated dynamically and
5248 differently on each system, should use <tt>adduser
5249 --system</tt> to create the group and/or user.
5250 <prgn>adduser</prgn> will check for the existence of
5251 the user or group, and if necessary choose an unused
5252 id based on the ranges specified in
5253 <file>adduser.conf</file>.
5257 <tag>1000-29999:</tag>
5260 Dynamically allocated user accounts. By default
5261 <prgn>adduser</prgn> will choose UIDs and GIDs for
5262 user accounts in this range, though
5263 <file>adduser.conf</file> may be used to modify this
5268 <tag>30000-59999:</tag>
5273 <tag>60000-64999:</tag>
5276 Globally allocated by the Debian project, but only
5277 created on demand. The ids are allocated centrally
5278 and statically, but the actual accounts are only
5279 created on users' systems on demand.
5283 These ids are for packages which are obscure or
5284 which require many statically-allocated ids. These
5285 packages should check for and create the accounts in
5286 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5287 <prgn>adduser</prgn> if it has this facility) if
5288 necessary. Packages which are likely to require
5289 further allocations should have a "hole" left after
5290 them in the allocation, to give them room to
5295 <tag>65000-65533:</tag>
5303 User <tt>nobody</tt>. The corresponding gid refers
5304 to the group <tt>nogroup</tt>.
5311 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5312 not</em> be used, because it is the error return
5321 <sect id="sysvinit">
5322 <heading>System run levels and <file>init.d</file> scripts</heading>
5324 <sect1 id="/etc/init.d">
5325 <heading>Introduction</heading>
5328 The <file>/etc/init.d</file> directory contains the scripts
5329 executed by <prgn>init</prgn> at boot time and when the
5330 init state (or "runlevel") is changed (see <manref
5331 name="init" section="8">).
5335 There are at least two different, yet functionally
5336 equivalent, ways of handling these scripts. For the sake
5337 of simplicity, this document describes only the symbolic
5338 link method. However, it must not be assumed by maintainer
5339 scripts that this method is being used, and any automated
5340 manipulation of the various runlevel behaviours by
5341 maintainer scripts must be performed using
5342 <prgn>update-rc.d</prgn> as described below and not by
5343 manually installing or removing symlinks. For information
5344 on the implementation details of the other method,
5345 implemented in the <tt>file-rc</tt> package, please refer
5346 to the documentation of that package.
5350 These scripts are referenced by symbolic links in the
5351 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5352 runlevels, <prgn>init</prgn> looks in the directory
5353 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5354 execute, where <tt><var>n</var></tt> is the runlevel that
5355 is being changed to, or <tt>S</tt> for the boot-up
5360 The names of the links all have the form
5361 <file>S<var>mm</var><var>script</var></file> or
5362 <file>K<var>mm</var><var>script</var></file> where
5363 <var>mm</var> is a two-digit number and <var>script</var>
5364 is the name of the script (this should be the same as the
5365 name of the actual script in <file>/etc/init.d</file>).
5369 When <prgn>init</prgn> changes runlevel first the targets
5370 of the links whose names start with a <tt>K</tt> are
5371 executed, each with the single argument <tt>stop</tt>,
5372 followed by the scripts prefixed with an <tt>S</tt>, each
5373 with the single argument <tt>start</tt>. (The links are
5374 those in the <file>/etc/rc<var>n</var>.d</file> directory
5375 corresponding to the new runlevel.) The <tt>K</tt> links
5376 are responsible for killing services and the <tt>S</tt>
5377 link for starting services upon entering the runlevel.
5381 For example, if we are changing from runlevel 2 to
5382 runlevel 3, init will first execute all of the <tt>K</tt>
5383 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5384 all of the <tt>S</tt> prefixed scripts in that directory.
5385 The links starting with <tt>K</tt> will cause the
5386 referred-to file to be executed with an argument of
5387 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5392 The two-digit number <var>mm</var> is used to determine
5393 the order in which to run the scripts: low-numbered links
5394 have their scripts run first. For example, the
5395 <tt>K20</tt> scripts will be executed before the
5396 <tt>K30</tt> scripts. This is used when a certain service
5397 must be started before another. For example, the name
5398 server <prgn>bind</prgn> might need to be started before
5399 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5400 can set up its access lists. In this case, the script
5401 that starts <prgn>bind</prgn> would have a lower number
5402 than the script that starts <prgn>inn</prgn> so that it
5404 <example compact="compact">
5411 The two runlevels 0 (halt) and 6 (reboot) are slightly
5412 different. In these runlevels, the links with an
5413 <tt>S</tt> prefix are still called after those with a
5414 <tt>K</tt> prefix, but they too are called with the single
5415 argument <tt>stop</tt>.
5419 Also, if the script name ends <tt>.sh</tt>, the script
5420 will be sourced in runlevel <tt>S</tt> rather that being
5421 run in a forked subprocess, but will be explicitly run by
5422 <prgn>sh</prgn> in all other runlevels.
5427 <heading>Writing the scripts</heading>
5430 Packages that include daemons for system services should
5431 place scripts in <file>/etc/init.d</file> to start or stop
5432 services at boot time or during a change of runlevel.
5433 These scripts should be named
5434 <file>/etc/init.d/<var>package</var></file>, and they should
5435 accept one argument, saying what to do:
5438 <tag><tt>start</tt></tag>
5439 <item>start the service,</item>
5441 <tag><tt>stop</tt></tag>
5442 <item>stop the service,</item>
5444 <tag><tt>restart</tt></tag>
5445 <item>stop and restart the service if it's already running,
5446 otherwise start the service</item>
5448 <tag><tt>reload</tt></tag>
5449 <item><p>cause the configuration of the service to be
5450 reloaded without actually stopping and restarting
5453 <tag><tt>force-reload</tt></tag>
5454 <item>cause the configuration to be reloaded if the
5455 service supports this, otherwise restart the
5459 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5460 <tt>force-reload</tt> options should be supported by all
5461 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5466 The <file>init.d</file> scripts should ensure that they will
5467 behave sensibly if invoked with <tt>start</tt> when the
5468 service is already running, or with <tt>stop</tt> when it
5469 isn't, and that they don't kill unfortunately-named user
5470 processes. The best way to achieve this is usually to use
5471 <prgn>start-stop-daemon</prgn>.
5475 If a service reloads its configuration automatically (as
5476 in the case of <prgn>cron</prgn>, for example), the
5477 <tt>reload</tt> option of the <file>init.d</file> script
5478 should behave as if the configuration has been reloaded
5483 The <file>/etc/init.d</file> scripts must be treated as
5484 configuration files, either (if they are present in the
5485 package, that is, in the .deb file) by marking them as
5486 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5487 by managing them correctly in the maintainer scripts (see
5488 <ref id="config-files">). This is important since we want
5489 to give the local system administrator the chance to adapt
5490 the scripts to the local system, e.g., to disable a
5491 service without de-installing the package, or to specify
5492 some special command line options when starting a service,
5493 while making sure their changes aren't lost during the next
5498 These scripts should not fail obscurely when the
5499 configuration files remain but the package has been
5500 removed, as configuration files remain on the system after
5501 the package has been removed. Only when <prgn>dpkg</prgn>
5502 is executed with the <tt>--purge</tt> option will
5503 configuration files be removed. In particular, as the
5504 <file>/etc/init.d/<var>package</var></file> script itself is
5505 usually a <tt>conffile</tt>, it will remain on the system
5506 if the package is removed but not purged. Therefore, you
5507 should include a <tt>test</tt> statement at the top of the
5509 <example compact="compact">
5510 test -f <var>program-executed-later-in-script</var> || exit 0
5515 Often there are some variables in the <file>init.d</file>
5516 scripts whose values control the behaviour of the scripts,
5517 and which a system administrator is likely to want to
5518 change. As the scripts themselves are frequently
5519 <tt>conffile</tt>s, modifying them requires that the
5520 administrator merge in their changes each time the package
5521 is upgraded and the <tt>conffile</tt> changes. To ease
5522 the burden on the system administrator, such configurable
5523 values should not be placed directly in the script.
5524 Instead, they should be placed in a file in
5525 <file>/etc/default</file>, which typically will have the same
5526 base name as the <file>init.d</file> script. This extra file
5527 should be sourced by the script when the script runs. It
5528 must contain only variable settings and comments in POSIX
5529 <prgn>sh</prgn> format. It may either be a
5530 <tt>conffile</tt> or a configuration file maintained by
5531 the package maintainer scripts. See <ref id="config-files">
5536 To ensure that vital configurable values are always
5537 available, the <file>init.d</file> script should set default
5538 values for each of the shell variables it uses, either
5539 before sourcing the <file>/etc/default/</file> file or
5540 afterwards using something like the <tt>:
5541 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5542 script must behave sensibly and not fail if the
5543 <file>/etc/default</file> file is deleted.
5548 <heading>Interfacing with the initscript system</heading>
5551 Maintainers should use the abstraction layer provided by
5552 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5553 programs to deal with initscripts in their packages'
5554 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5555 and <prgn>postrm</prgn>.
5559 Directly managing the /etc/rc?.d links and directly
5560 invoking the <file>/etc/init.d/</file> initscripts should
5561 be done only by packages providing the initscript
5562 subsystem (such as <prgn>sysv-rc</prgn> and
5563 <prgn>file-rc</prgn>).
5567 <heading>Managing the links</heading>
5570 The program <prgn>update-rc.d</prgn> is provided for
5571 package maintainers to arrange for the proper creation and
5572 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5573 or their functional equivalent if another method is being
5574 used. This may be used by maintainers in their packages'
5575 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5579 You must not include any <file>/etc/rc<var>n</var>.d</file>
5580 symbolic links in the actual archive or manually create or
5581 remove the symbolic links in maintainer scripts; you must
5582 use the <prgn>update-rc.d</prgn> program instead. (The
5583 former will fail if an alternative method of maintaining
5584 runlevel information is being used.) You must not include
5585 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5586 in the archive either. (Only the <tt>sysvinit</tt>
5591 By default <prgn>update-rc.d</prgn> will start services in
5592 each of the multi-user state runlevels (2, 3, 4, and 5)
5593 and stop them in the halt runlevel (0), the single-user
5594 runlevel (1) and the reboot runlevel (6). The system
5595 administrator will have the opportunity to customize
5596 runlevels by simply adding, moving, or removing the
5597 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5598 symbolic links are being used, or by modifying
5599 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5604 To get the default behavior for your package, put in your
5605 <prgn>postinst</prgn> script
5606 <example compact="compact">
5607 update-rc.d <var>package</var> defaults
5609 and in your <prgn>postrm</prgn>
5610 <example compact="compact">
5611 if [ "$1" = purge ]; then
5612 update-rc.d <var>package</var> remove
5614 </example>. Note that if your package changes runlevels
5615 or priority, you may have to remove and recreate the links,
5616 since otherwise the old links may persist. Refer to the
5617 documentation of <prgn>update-rc.d</prgn>.
5621 This will use a default sequence number of 20. If it does
5622 not matter when or in which order the <file>init.d</file>
5623 script is run, use this default. If it does, then you
5624 should talk to the maintainer of the <prgn>sysvinit</prgn>
5625 package or post to <tt>debian-devel</tt>, and they will
5626 help you choose a number.
5630 For more information about using <tt>update-rc.d</tt>,
5631 please consult its man page <manref name="update-rc.d"
5637 <heading>Running initscripts</heading>
5639 The program <prgn>invoke-rc.d</prgn> is provided to make
5640 it easier for package maintainers to properly invoke an
5641 initscript, obeying runlevel and other locally-defined
5642 constraints that might limit a package's right to start,
5643 stop and otherwise manage services. This program may be
5644 used by maintainers in their packages' scripts.
5648 The use of <prgn>invoke-rc.d</prgn> to invoke the
5649 <file>/etc/init.d/*</file> initscripts is strongly
5650 recommended<footnote>
5651 In the future, the use of invoke-rc.d to invoke
5652 initscripts shall be made mandatory. Maintainers are
5653 advised to switch to invoke-rc.d as soon as
5655 </footnote>, instead of calling them directly.
5659 By default, <prgn>invoke-rc.d</prgn> will pass any
5660 action requests (start, stop, reload, restart...) to the
5661 <file>/etc/init.d</file> script, filtering out requests
5662 to start or restart a service out of its intended
5667 Most packages will simply need to change:
5668 <example compact="compact">/etc/init.d/<package>
5669 <action></example> in their <prgn>postinst</prgn>
5670 and <prgn>prerm</prgn> scripts to:
5671 <example compact="compact">
5672 if which invoke-rc.d >/dev/null 2>&1; then
5673 invoke-rc.d <var>package</var> <action>
5675 /etc/init.d/<var>package</var> <action>
5681 A package should register its initscript services using
5682 <prgn>update-rc.d</prgn> before it tries to invoke them
5683 using <prgn>invoke-rc.d</prgn>. Invocation of
5684 unregistered services may fail.
5688 For more information about using
5689 <prgn>invoke-rc.d</prgn>, please consult its man page
5690 <manref name="invoke-rc.d" section="8">.
5696 <heading>Boot-time initialization</heading>
5699 There used to be another directory, <file>/etc/rc.boot</file>,
5700 which contained scripts which were run once per machine
5701 boot. This has been deprecated in favour of links from
5702 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5703 described in <ref id="/etc/init.d">. Packages must not
5704 place files in <file>/etc/rc.boot</file>.
5709 <heading>Example</heading>
5712 The <prgn>bind</prgn> DNS (nameserver) package wants to
5713 make sure that the nameserver is running in multiuser
5714 runlevels, and is properly shut down with the system. It
5715 puts a script in <file>/etc/init.d</file>, naming the script
5716 appropriately <tt>bind</tt>. As you can see, the script
5717 interprets the argument <tt>reload</tt> to send the
5718 nameserver a <tt>HUP</tt> signal (causing it to reload its
5719 configuration); this way the system administrator can say
5720 <tt>/etc/init.d/bind reload</tt> to reload the name
5721 server. The script has one configurable value, which can
5722 be used to pass parameters to the named program at
5723 startup; this value is read from
5724 <file>/etc/default/bind</file> (see below).
5728 <example compact="compact">
5731 # Original version by Robert Leslie
5732 # <rob@mars.org>, edited by iwj and cs
5734 test -x /usr/sbin/named || exit 0
5736 # Source defaults file.
5738 if [ -f /etc/default/bind ]; then
5745 echo -n "Starting domain name service: named"
5746 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5751 echo -n "Stopping domain name service: named"
5752 start-stop-daemon --stop --quiet \
5753 --pidfile /var/run/named.pid --exec /usr/sbin/named
5757 echo -n "Restarting domain name service: named"
5758 start-stop-daemon --stop --quiet --oknodo \
5759 --pidfile /var/run/named.pid --exec /usr/sbin/named
5760 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5764 force-reload|reload)
5765 echo -n "Reloading configuration of domain name service: named"
5766 start-stop-daemon --stop --signal 1 --quiet \
5767 --pidfile /var/run/named.pid --exec /usr/sbin/named
5771 echo "Usage: /etc/init.d/bind " \
5772 " {start|stop|restart|reload|force-reload}" >&2
5782 Complementing the above init script is a configuration
5783 file <file>/etc/default/bind</file>, which contains
5784 configurable parameters used by the script. This would be
5785 created by the <prgn>postinst</prgn> script if it was not
5786 already present, and removed on purge by the
5787 <prgn>postrm</prgn> script.
5788 <example compact="compact">
5789 # Specified parameters to pass to named. See named(8).
5790 # You may uncomment the following line, and edit to taste.
5796 Another example on which you can base your
5797 <file>/etc/init.d</file> scripts is found in
5798 <file>/etc/init.d/skeleton</file>.
5802 If this package is happy with the default setup from
5803 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5804 and having named running in all runlevels, it can say in
5805 its <prgn>postinst</prgn>:
5806 <example compact="compact">
5807 update-rc.d bind defaults >/dev/null
5809 And in its <prgn>postrm</prgn>, to remove the links when the
5811 <example compact="compact">
5812 if [ "$1" = purge ]; then
5813 update-rc.d bind remove >/dev/null
5821 <heading>Console messages from <file>init.d</file> scripts</heading>
5824 This section describes the formats to be used for messages
5825 written to standard output by the <file>/etc/init.d</file>
5826 scripts. The intent is to improve the consistency of
5827 Debian's startup and shutdown look and feel. For this
5828 reason, please look very carefully at the details. We want
5829 the messages to have the same format in terms of wording,
5830 spaces, punctuation and case of letters.
5834 Here is a list of overall rules that should be used for
5835 messages generated by <file>/etc/init.d</file> scripts.
5841 The message should fit in one line (fewer than 80
5842 characters), start with a capital letter and end with
5843 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5847 If the script is performing some time consuming task in
5848 the background (not merely starting or stopping a
5849 program, for instance), an ellipsis (three dots:
5850 <tt>...</tt>) should be output to the screen, with no
5851 leading or tailing whitespace or line feeds.
5855 The messages should appear as if the computer is telling
5856 the user what it is doing (politely :-), but should not
5857 mention "it" directly. For example, instead of:
5858 <example compact="compact">
5859 I'm starting network daemons: nfsd mountd.
5861 the message should say
5862 <example compact="compact">
5863 Starting network daemons: nfsd mountd.
5870 <tt>init.d</tt> script should use the following standard
5871 message formats for the situations enumerated below.
5877 <p>When daemons are started</p>
5880 If the script starts one or more daemons, the output
5881 should look like this (a single line, no leading
5883 <example compact="compact">
5884 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5886 The <var>description</var> should describe the
5887 subsystem the daemon or set of daemons are part of,
5888 while <var>daemon-1</var> up to <var>daemon-n</var>
5889 denote each daemon's name (typically the file name of
5894 For example, the output of <file>/etc/init.d/lpd</file>
5896 <example compact="compact">
5897 Starting printer spooler: lpd.
5902 This can be achieved by saying
5903 <example compact="compact">
5904 echo -n "Starting printer spooler: lpd"
5905 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5908 in the script. If there are more than one daemon to
5909 start, the output should look like this:
5910 <example compact="compact">
5911 echo -n "Starting remote file system services:"
5912 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5913 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5914 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5917 This makes it possible for the user to see what is
5918 happening and when the final daemon has been started.
5919 Care should be taken in the placement of white spaces:
5920 in the example above the system administrators can
5921 easily comment out a line if they don't want to start
5922 a specific daemon, while the displayed message still
5928 <p>When a system parameter is being set</p>
5931 If you have to set up different system parameters
5932 during the system boot, you should use this format:
5933 <example compact="compact">
5934 Setting <var>parameter</var> to "<var>value</var>".
5939 You can use a statement such as the following to get
5941 <example compact="compact">
5942 echo "Setting DNS domainname to \"$domainname\"."
5947 Note that the same symbol (<tt>"</tt>) is used for the left
5948 and right quotation marks. A grave accent (<tt>`</tt>) is
5949 not a quote character; neither is an apostrophe
5955 <p>When a daemon is stopped or restarted</p>
5958 When you stop or restart a daemon, you should issue a
5959 message identical to the startup message, except that
5960 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5961 or <tt>Restarting</tt> respectively.
5965 For example, stopping the printer daemon will like
5967 <example compact="compact">
5968 Stopping printer spooler: lpd.
5974 <p>When something is executed</p>
5977 There are several examples where you have to run a
5978 program at system startup or shutdown to perform a
5979 specific task, for example, setting the system's clock
5980 using <prgn>netdate</prgn> or killing all processes
5981 when the system shuts down. Your message should look
5983 <example compact="compact">
5984 Doing something very useful...done.
5986 You should print the <tt>done.</tt> immediately after
5987 the job has been completed, so that the user is
5988 informed why they have to wait. You can get this
5990 <example compact="compact">
5991 echo -n "Doing something very useful..."
6000 <p>When the configuration is reloaded</p>
6003 When a daemon is forced to reload its configuration
6004 files you should use the following format:
6005 <example compact="compact">
6006 Reloading <var>description</var> configuration...done.
6008 where <var>description</var> is the same as in the
6009 daemon starting message.
6017 <heading>Cron jobs</heading>
6020 Packages must not modify the configuration file
6021 <file>/etc/crontab</file>, and they must not modify the files in
6022 <file>/var/spool/cron/crontabs</file>.</p>
6025 If a package wants to install a job that has to be executed
6026 via cron, it should place a file with the name of the
6027 package in one or more of the following directories:
6028 <example compact="compact">
6033 As these directory names imply, the files within them are
6034 executed on a daily, weekly, or monthly basis,
6035 respectively. The exact times are listed in
6036 <file>/etc/crontab</file>.</p>
6039 All files installed in any of these directories must be
6040 scripts (e.g., shell scripts or Perl scripts) so that they
6041 can easily be modified by the local system administrator.
6042 In addition, they should be treated as configuration
6047 If a certain job has to be executed more frequently than
6048 daily, the package should install a file
6049 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6050 same syntax as <file>/etc/crontab</file> and is processed by
6051 <prgn>cron</prgn> automatically. The file must also be
6052 treated as a configuration file. (Note that entries in the
6053 <file>/etc/cron.d</file> directory are not handled by
6054 <prgn>anacron</prgn>. Thus, you should only use this
6055 directory for jobs which may be skipped if the system is not
6059 The scripts or crontab entries in these directories should
6060 check if all necessary programs are installed before they
6061 try to execute them. Otherwise, problems will arise when a
6062 package was removed but not purged since configuration files
6063 are kept on the system in this situation.</p>
6067 <heading>Menus</heading>
6070 The Debian <tt>menu</tt> package provides a standard
6071 interface between packages providing applications and
6072 <em>menu programs</em> (either X window managers or
6073 text-based menu programs such as <prgn>pdmenu</prgn>).
6077 All packages that provide applications that need not be
6078 passed any special command line arguments for normal
6079 operation should register a menu entry for those
6080 applications, so that users of the <tt>menu</tt> package
6081 will automatically get menu entries in their window
6082 managers, as well in shells like <tt>pdmenu</tt>.
6086 Menu entries should follow the current menu policy.
6090 The menu policy can be found in the <tt>menu-policy</tt>
6091 files in the <tt>debian-policy</tt> package.
6092 It is also available from the Debian web mirrors at
6093 <tt><url name="/doc/packaging-manuals/menu-policy/"
6094 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6098 Please also refer to the <em>Debian Menu System</em>
6099 documentation that comes with the <package>menu</package>
6100 package for information about how to register your
6106 <heading>Multimedia handlers</heading>
6109 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6110 is a mechanism for encoding files and data streams and
6111 providing meta-information about them, in particular their
6112 type (e.g. audio or video) and format (e.g. PNG, HTML,
6117 Registration of MIME type handlers allows programs like mail
6118 user agents and web browsers to invoke these handlers to
6119 view, edit or display MIME types they don't support directly.
6123 Packages which provide the ability to view/show/play,
6124 compose, edit or print MIME types should register themselves
6125 as such following the current MIME support policy.
6129 The MIME support policy can be found in the <tt>mime-policy</tt>
6130 files in the <tt>debian-policy</tt> package.
6131 It is also available from the Debian web mirrors at
6132 <tt><url name="/doc/packaging-manuals/mime-policy/"
6133 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6139 <heading>Keyboard configuration</heading>
6142 To achieve a consistent keyboard configuration so that all
6143 applications interpret a keyboard event the same way, all
6144 programs in the Debian distribution must be configured to
6145 comply with the following guidelines.
6149 The following keys must have the specified interpretations:
6152 <tag><tt><--</tt></tag>
6153 <item>delete the character to the left of the cursor</item>
6155 <tag><tt>Delete</tt></tag>
6156 <item>delete the character to the right of the cursor</item>
6158 <tag><tt>Control+H</tt></tag>
6159 <item>emacs: the help prefix</item>
6162 The interpretation of any keyboard events should be
6163 independent of the terminal that is used, be it a virtual
6164 console, an X terminal emulator, an rlogin/telnet session,
6169 The following list explains how the different programs
6170 should be set up to achieve this:
6176 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6180 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6184 X translations are set up to make
6185 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6186 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6187 is the vt220 escape code for the "delete character"
6188 key). This must be done by loading the X resources
6189 using <prgn>xrdb</prgn> on all local X displays, not
6190 using the application defaults, so that the
6191 translation resources used correspond to the
6192 <prgn>xmodmap</prgn> settings.
6196 The Linux console is configured to make
6197 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6198 generate <tt>ESC [ 3 ~</tt>.
6202 X applications are configured so that <tt><</tt>
6203 deletes left, and <tt>Delete</tt> deletes right. Motif
6204 applications already work like this.
6208 Terminals should have <tt>stty erase ^?</tt> .
6212 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6213 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6214 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6218 Emacs is programmed to map <tt>KB_Backspace</tt> or
6219 the <tt>stty erase</tt> character to
6220 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6221 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6222 <tt>^H</tt> to <tt>help</tt> as always.
6226 Other applications use the <tt>stty erase</tt>
6227 character and <tt>kdch1</tt> for the two delete keys,
6228 with ASCII DEL being "delete previous character" and
6229 <tt>kdch1</tt> being "delete character under
6237 This will solve the problem except for the following
6244 Some terminals have a <tt><--</tt> key that cannot
6245 be made to produce anything except <tt>^H</tt>. On
6246 these terminals Emacs help will be unavailable on
6247 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6248 character takes precedence in Emacs, and has been set
6249 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6250 available) can be used instead.
6254 Some operating systems use <tt>^H</tt> for <tt>stty
6255 erase</tt>. However, modern telnet versions and all
6256 rlogin versions propagate <tt>stty</tt> settings, and
6257 almost all UNIX versions honour <tt>stty erase</tt>.
6258 Where the <tt>stty</tt> settings are not propagated
6259 correctly, things can be made to work by using
6260 <tt>stty</tt> manually.
6264 Some systems (including previous Debian versions) use
6265 <prgn>xmodmap</prgn> to arrange for both
6266 <tt><--</tt> and <tt>Delete</tt> to generate
6267 <tt>KB_Delete</tt>. We can change the behavior of
6268 their X clients using the same X resources that we use
6269 to do it for our own clients, or configure our clients
6270 using their resources when things are the other way
6271 around. On displays configured like this
6272 <tt>Delete</tt> will not work, but <tt><--</tt>
6277 Some operating systems have different <tt>kdch1</tt>
6278 settings in their <tt>terminfo</tt> database for
6279 <tt>xterm</tt> and others. On these systems the
6280 <tt>Delete</tt> key will not work correctly when you
6281 log in from a system conforming to our policy, but
6282 <tt><--</tt> will.
6289 <heading>Environment variables</heading>
6292 A program must not depend on environment variables to get
6293 reasonable defaults. (That's because these environment
6294 variables would have to be set in a system-wide
6295 configuration file like <file>/etc/profile</file>, which is not
6296 supported by all shells.)
6300 If a program usually depends on environment variables for its
6301 configuration, the program should be changed to fall back to
6302 a reasonable default configuration if these environment
6303 variables are not present. If this cannot be done easily
6304 (e.g., if the source code of a non-free program is not
6305 available), the program must be replaced by a small
6306 "wrapper" shell script which sets the environment variables
6307 if they are not already defined, and calls the original program.
6311 Here is an example of a wrapper script for this purpose:
6313 <example compact="compact">
6315 BAR=${BAR:-/var/lib/fubar}
6317 exec /usr/lib/foo/foo "$@"
6322 Furthermore, as <file>/etc/profile</file> is a configuration
6323 file of the <prgn>base-files</prgn> package, other packages must
6324 not put any environment variables or other commands into that
6329 <sect id="doc-base">
6330 <heading>Registering Documents using doc-base</heading>
6333 The <package>doc-base</package> package implements a
6334 flexible mechanism for handling and presenting
6335 documentation. The recommended practice is for every Debian
6336 package that provides online documentation (other than just
6337 manual pages) to register these documents with
6338 <package>doc-base</package> by installing a
6339 <package>doc-base</package> control file via the
6340 <prgn/install-docs/ script at installation time and
6341 de-register the manuals again when the package is removed.
6344 Please refer to the documentation that comes with the
6345 <package>doc-base</package> package for information and
6354 <heading>Files</heading>
6357 <heading>Binaries</heading>
6360 Two different packages must not install programs with
6361 different functionality but with the same filenames. (The
6362 case of two programs having the same functionality but
6363 different implementations is handled via "alternatives" or
6364 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6365 <ref id="conflicts"> respectively.) If this case happens,
6366 one of the programs must be renamed. The maintainers should
6367 report this to the <tt>debian-devel</tt> mailing list and
6368 try to find a consensus about which program will have to be
6369 renamed. If a consensus cannot be reached, <em>both</em>
6370 programs must be renamed.
6374 By default, when a package is being built, any binaries
6375 created should include debugging information, as well as
6376 being compiled with optimization. You should also turn on
6377 as many reasonable compilation warnings as possible; this
6378 makes life easier for porters, who can then look at build
6379 logs for possible problems. For the C programming language,
6380 this means the following compilation parameters should be
6382 <example compact="compact">
6384 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6386 install -s # (or use strip on the files in debian/tmp)
6391 Note that by default all installed binaries should be stripped,
6392 either by using the <tt>-s</tt> flag to
6393 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6394 the binaries after they have been copied into
6395 <file>debian/tmp</file> but before the tree is made into a
6400 Although binaries in the build tree should be compiled with
6401 debugging information by default, it can often be difficult
6402 to debug programs if they are also subjected to compiler
6403 optimization. For this reason, it is recommended to support
6404 the standardized environment
6405 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6406 contain several flags to change how a package is compiled
6414 The presence of this string means that the package
6415 should be compiled with a minimum of optimization.
6416 For C programs, it is best to add <tt>-O0</tt>
6417 to <tt>CFLAGS</tt> (although this is usually the
6418 default). Some programs might fail to build or run at
6419 this level of optimization; it may be necessary to
6420 use <tt>-O1</tt>, for example.
6424 This string means that the debugging symbols should
6425 not be stripped from the binary during installation,
6426 so that debugging information may be included in the package.
6432 The following makefile snippet is an example of how one may
6433 implement the build options; you will probably have to
6434 massage this example in order to make it work for your
6436 <example compact="compact">
6439 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6440 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6441 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6442 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6444 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6449 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6450 INSTALL_PROGRAM += -s
6456 It is up to the package maintainer to decide what
6457 compilation options are best for the package. Certain
6458 binaries (such as computationally-intensive programs) will
6459 function better with certain flags (<tt>-O3</tt>, for
6460 example); feel free to use them. Please use good judgment
6461 here. Don't use flags for the sake of it; only use them
6462 if there is good reason to do so. Feel free to override
6463 the upstream author's ideas about which compilation
6464 options are best: they are often inappropriate for our
6470 <sect id="libraries">
6471 <heading>Libraries</heading>
6474 The shared version of a library must be compiled with
6475 <tt>-fPIC</tt>, and the static version must not be. In other
6476 words, each source unit (<tt>*.c</tt>, for example, for C files)
6477 will need to be compiled twice.
6481 You must specify the gcc option <tt>-D_REENTRANT</tt>
6482 when building a library (either static or shared) to make
6483 the library compatible with LinuxThreads.
6487 Although not enforced by the build tools, shared libraries
6488 must be linked against all libraries that they use symbols from
6489 in the same way that binaries are. This ensures the correct
6490 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6491 system and guarantees that all libraries can be safely opened
6492 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6493 option <tt>-Wl,-z,defs</tt> when building a shared library.
6494 Since this option enforces symbol resolution at build time,
6495 a missing library reference will be caught early as a fatal
6500 All installed shared libraries should be stripped with
6501 <example compact="compact">
6502 strip --strip-unneeded <var>your-lib</var>
6504 (The option <tt>--strip-unneeded</tt> makes
6505 <prgn>strip</prgn> remove only the symbols which aren't
6506 needed for relocation processing.) Shared libraries can
6507 function perfectly well when stripped, since the symbols for
6508 dynamic linking are in a separate part of the ELF object
6510 You might also want to use the options
6511 <tt>--remove-section=.comment</tt> and
6512 <tt>--remove-section=.note</tt> on both shared libraries
6513 and executables, and <tt>--strip-debug</tt> on static
6519 Note that under some circumstances it may be useful to
6520 install a shared library unstripped, for example when
6521 building a separate package to support debugging.
6525 Shared object files (often <file>.so</file> files) that are not
6526 public libraries, that is, they are not meant to be linked
6527 to by third party executables (binaries of other packages),
6528 should be installed in subdirectories of the
6529 <file>/usr/lib</file> directory. Such files are exempt from the
6530 rules that govern ordinary shared libraries, except that
6531 they must not be installed executable and should be
6533 A common example are the so-called "plug-ins",
6534 internal shared objects that are dynamically loaded by
6535 programs using <manref name="dlopen" section="3">.
6540 Packages containing shared libraries that may be linked to
6541 by other packages' binaries, but which for some
6542 <em>compelling</em> reason can not be installed in
6543 <file>/usr/lib</file> directory, may install the shared library
6544 files in subdirectories of the <file>/usr/lib</file> directory,
6545 in which case they should arrange to add that directory in
6546 <file>/etc/ld.so.conf</file> in the package's post-installation
6547 script, and remove it in the package's post-removal script.
6551 An ever increasing number of packages are using
6552 <prgn>libtool</prgn> to do their linking. The latest GNU
6553 libtools (>= 1.3a) can take advantage of the metadata in the
6554 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6555 files). The main advantage of <prgn>libtool</prgn>'s
6556 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6557 store and subsequently access metadata with respect to the
6558 libraries it builds. <prgn>libtool</prgn> will search for
6559 those files, which contain a lot of useful information about
6560 a library (such as library dependency information for static
6561 linking). Also, they're <em>essential</em> for programs
6562 using <tt>libltdl</tt>.<footnote>
6563 Although <prgn>libtool</prgn> is fully capable of
6564 linking against shared libraries which don't have
6565 <tt>.la</tt> files, as it is a mere shell script it can
6566 add considerably to the build time of a
6567 <prgn>libtool</prgn>-using package if that shell script
6568 has to derive all this information from first principles
6569 for each library every time it is linked. With the
6570 advent of <prgn>libtool</prgn> version 1.4 (and to a
6571 lesser extent <prgn>libtool</prgn> version 1.3), the
6572 <file>.la</file> files also store information about
6573 inter-library dependencies which cannot necessarily be
6574 derived after the <file>.la</file> file is deleted.
6579 Packages that use <prgn>libtool</prgn> to create shared
6580 libraries should include the <file>.la</file> files in the
6581 <tt>-dev</tt> package, unless the package relies on
6582 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6583 the <tt>.la</tt> files must go in the run-time library
6588 You must make sure that you use only released versions of
6589 shared libraries to build your packages; otherwise other
6590 users will not be able to run your binaries
6591 properly. Producing source packages that depend on
6592 unreleased compilers is also usually a bad
6599 <heading>Shared libraries</heading>
6601 This section has moved to <ref id="sharedlibs">.
6607 <heading>Scripts</heading>
6610 All command scripts, including the package maintainer
6611 scripts inside the package and used by <prgn>dpkg</prgn>,
6612 should have a <tt>#!</tt> line naming the shell to be used
6617 In the case of Perl scripts this should be
6618 <tt>#!/usr/bin/perl</tt>.
6622 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6623 should almost certainly start with <tt>set -e</tt> so that
6624 errors are detected. Every script should use
6625 <tt>set -e</tt> or check the exit status of <em>every</em>
6630 The standard shell interpreter <file>/bin/sh</file> can be a
6631 symbolic link to any POSIX compatible shell, if <tt>echo
6632 -n</tt> does not generate a newline.<footnote>
6633 Debian policy specifies POSIX behavior for
6634 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6635 use in the Linux community (in particular including this
6636 policy, the Linux kernel source, many Debian scripts,
6637 etc.). This <tt>echo -n</tt> mechanism is valid but not
6638 required under POSIX, hence this explicit addition.
6639 Also, rumour has it that this shall be mandated under
6642 Thus, shell scripts specifying <file>/bin/sh</file> as
6643 interpreter should only use POSIX features. If a script
6644 requires non-POSIX features from the shell interpreter, the
6645 appropriate shell must be specified in the first line of the
6646 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6647 depend on the package providing the shell (unless the shell
6648 package is marked "Essential", as in the case of
6653 You may wish to restrict your script to POSIX features when
6654 possible so that it may use <file>/bin/sh</file> as its
6655 interpreter. If your script works with <prgn>dash</prgn>
6656 (originally called <prgn>ash</prgn>), it's probably POSIX
6657 compliant, but if you are in doubt, use
6658 <file>/bin/bash</file>.
6662 Perl scripts should check for errors when making any
6663 system calls, including <tt>open</tt>, <tt>print</tt>,
6664 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6668 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6669 scripting languages. See <em>Csh Programming Considered
6670 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6671 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
6672 If an upstream package comes with <prgn>csh</prgn> scripts
6673 then you must make sure that they start with
6674 <tt>#!/bin/csh</tt> and make your package depend on the
6675 <prgn>c-shell</prgn> virtual package.
6679 Any scripts which create files in world-writeable
6680 directories (e.g., in <file>/tmp</file>) must use a
6681 mechanism which will fail if a file with the same name
6686 The Debian base system provides the <prgn>tempfile</prgn>
6687 and <prgn>mktemp</prgn> utilities for use by scripts for
6694 <heading>Symbolic links</heading>
6697 In general, symbolic links within a top-level directory
6698 should be relative, and symbolic links pointing from one
6699 top-level directory into another should be absolute. (A
6700 top-level directory is a sub-directory of the root
6701 directory <file>/</file>.)
6705 In addition, symbolic links should be specified as short as
6706 possible, i.e., link targets like <file>foo/../bar</file> are
6711 Note that when creating a relative link using
6712 <prgn>ln</prgn> it is not necessary for the target of the
6713 link to exist relative to the working directory you're
6714 running <prgn>ln</prgn> from, nor is it necessary to change
6715 directory to the directory where the link is to be made.
6716 Simply include the string that should appear as the target
6717 of the link (this will be a pathname relative to the
6718 directory in which the link resides) as the first argument
6723 For example, in your <prgn>Makefile</prgn> or
6724 <file>debian/rules</file>, you can do things like:
6725 <example compact="compact">
6726 ln -fs gcc $(prefix)/bin/cc
6727 ln -fs gcc debian/tmp/usr/bin/cc
6728 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6729 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6734 A symbolic link pointing to a compressed file should always
6735 have the same file extension as the referenced file. (For
6736 example, if a file <file>foo.gz</file> is referenced by a
6737 symbolic link, the filename of the link has to end with
6738 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6743 <heading>Device files</heading>
6746 Packages must not include device files in the package file
6751 If a package needs any special device files that are not
6752 included in the base system, it must call
6753 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6754 after notifying the user<footnote>
6755 This notification could be done via a (low-priority)
6756 debconf message, or an echo (printf) statement.
6761 Packages must not remove any device files in the
6762 <prgn>postrm</prgn> or any other script. This is left to the
6763 system administrator.
6767 Debian uses the serial devices
6768 <file>/dev/ttyS*</file>. Programs using the old
6769 <file>/dev/cu*</file> devices should be changed to use
6770 <file>/dev/ttyS*</file>.
6774 <sect id="config-files">
6775 <heading>Configuration files</heading>
6778 <heading>Definitions</heading>
6782 <tag>configuration file</tag>
6784 A file that affects the operation of a program, or
6785 provides site- or host-specific information, or
6786 otherwise customizes the behavior of a program.
6787 Typically, configuration files are intended to be
6788 modified by the system administrator (if needed or
6789 desired) to conform to local policy or to provide
6790 more useful site-specific behavior.
6793 <tag><tt>conffile</tt></tag>
6795 A file listed in a package's <tt>conffiles</tt>
6796 file, and is treated specially by <prgn>dpkg</prgn>
6797 (see <ref id="configdetails">).
6803 The distinction between these two is important; they are
6804 not interchangeable concepts. Almost all
6805 <tt>conffile</tt>s are configuration files, but many
6806 configuration files are not <tt>conffiles</tt>.
6810 Note that a script that embeds configuration information
6811 (such as most of the files in <file>/etc/default</file> and
6812 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6813 configuration file and should be treated as such.
6818 <heading>Location</heading>
6821 Any configuration files created or used by your package
6822 must reside in <file>/etc</file>. If there are several,
6823 consider creating a subdirectory of <file>/etc</file>
6824 named after your package.
6828 If your package creates or uses configuration files
6829 outside of <file>/etc</file>, and it is not feasible to modify
6830 the package to use <file>/etc</file> directly, put the files
6831 in <file>/etc</file> and create symbolic links to those files
6832 from the location that the package requires.
6837 <heading>Behavior</heading>
6840 Configuration file handling must conform to the following
6842 <list compact="compact">
6844 local changes must be preserved during a package
6848 configuration files must be preserved when the
6849 package is removed, and only deleted when the
6856 The easy way to achieve this behavior is to make the
6857 configuration file a <tt>conffile</tt>. This is
6858 appropriate only if it is possible to distribute a default
6859 version that will work for most installations, although
6860 some system administrators may choose to modify it. This
6861 implies that the default version will be part of the
6862 package distribution, and must not be modified by the
6863 maintainer scripts during installation (or at any other
6868 In order to ensure that local changes are preserved
6869 correctly, no package may contain or make hard links to
6870 conffiles.<footnote>
6871 Rationale: There are two problems with hard links.
6872 The first is that some editors break the link while
6873 editing one of the files, so that the two files may
6874 unwittingly become unlinked and different. The second
6875 is that <prgn>dpkg</prgn> might break the hard link
6876 while upgrading <tt>conffile</tt>s.
6881 The other way to do it is via the maintainer scripts. In
6882 this case, the configuration file must not be listed as a
6883 <tt>conffile</tt> and must not be part of the package
6884 distribution. If the existence of a file is required for
6885 the package to be sensibly configured it is the
6886 responsibility of the package maintainer to provide
6887 maintainer scripts which correctly create, update and
6888 maintain the file and remove it on purge. (See <ref
6889 id="maintainerscripts"> for more information.) These
6890 scripts must be idempotent (i.e., must work correctly if
6891 <prgn>dpkg</prgn> needs to re-run them due to errors
6892 during installation or removal), must cope with all the
6893 variety of ways <prgn>dpkg</prgn> can call maintainer
6894 scripts, must not overwrite or otherwise mangle the user's
6895 configuration without asking, must not ask unnecessary
6896 questions (particularly during upgrades), and otherwise be
6901 The scripts are not required to configure every possible
6902 option for the package, but only those necessary to get
6903 the package running on a given system. Ideally the
6904 sysadmin should not have to do any configuration other
6905 than that done (semi-)automatically by the
6906 <prgn>postinst</prgn> script.
6910 A common practice is to create a script called
6911 <file><var>package</var>-configure</file> and have the
6912 package's <prgn>postinst</prgn> call it if and only if the
6913 configuration file does not already exist. In certain
6914 cases it is useful for there to be an example or template
6915 file which the maintainer scripts use. Such files should
6916 be in <file>/usr/share/<var>package</var></file> or
6917 <file>/usr/lib/<var>package</var></file> (depending on whether
6918 they are architecture-independent or not). There should
6919 be symbolic links to them from
6920 <file>/usr/share/doc/<var>package</var>/examples</file> if
6921 they are examples, and should be perfectly ordinary
6922 <prgn>dpkg</prgn>-handled files (<em>not</em>
6923 configuration files).
6927 These two styles of configuration file handling must
6928 not be mixed, for that way lies madness:
6929 <prgn>dpkg</prgn> will ask about overwriting the file
6930 every time the package is upgraded.
6935 <heading>Sharing configuration files</heading>
6938 Packages which specify the same file as a
6939 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6940 with each other. (This is an instance of the general rule
6941 about not sharing files. Note that neither alternatives
6942 nor diversions are likely to be appropriate in this case;
6943 in particular, <prgn>dpkg</prgn> does not handle diverted
6944 <tt>conffile</tt>s well.)
6948 The maintainer scripts must not alter a <tt>conffile</tt>
6949 of <em>any</em> package, including the one the scripts
6954 If two or more packages use the same configuration file
6955 and it is reasonable for both to be installed at the same
6956 time, one of these packages must be defined as
6957 <em>owner</em> of the configuration file, i.e., it will be
6958 the package which handles that file as a configuration
6959 file. Other packages that use the configuration file must
6960 depend on the owning package if they require the
6961 configuration file to operate. If the other package will
6962 use the configuration file if present, but is capable of
6963 operating without it, no dependency need be declared.
6967 If it is desirable for two or more related packages to
6968 share a configuration file <em>and</em> for all of the
6969 related packages to be able to modify that configuration
6970 file, then the following should be done:
6971 <enumlist compact="compact">
6973 One of the related packages (the "owning" package)
6974 will manage the configuration file with maintainer
6975 scripts as described in the previous section.
6978 The owning package should also provide a program
6979 that the other packages may use to modify the
6983 The related packages must use the provided program
6984 to make any desired modifications to the
6985 configuration file. They should either depend on
6986 the core package to guarantee that the configuration
6987 modifier program is available or accept gracefully
6988 that they cannot modify the configuration file if it
6989 is not. (This is in addition to the fact that the
6990 configuration file may not even be present in the
6997 Sometimes it's appropriate to create a new package which
6998 provides the basic infrastructure for the other packages
6999 and which manages the shared configuration files. (The
7000 <tt>sgml-base</tt> package is a good example.)
7005 <heading>User configuration files ("dotfiles")</heading>
7008 The files in <file>/etc/skel</file> will automatically be
7009 copied into new user accounts by <prgn>adduser</prgn>.
7010 No other program should reference the files in
7011 <file>/etc/skel</file>.
7015 Therefore, if a program needs a dotfile to exist in
7016 advance in <file>$HOME</file> to work sensibly, that dotfile
7017 should be installed in <file>/etc/skel</file> and treated as a
7022 However, programs that require dotfiles in order to
7023 operate sensibly are a bad thing, unless they do create
7024 the dotfiles themselves automatically.
7028 Furthermore, programs should be configured by the Debian
7029 default installation to behave as closely to the upstream
7030 default behaviour as possible.
7034 Therefore, if a program in a Debian package needs to be
7035 configured in some way in order to operate sensibly, that
7036 should be done using a site-wide configuration file placed
7037 in <file>/etc</file>. Only if the program doesn't support a
7038 site-wide default configuration and the package maintainer
7039 doesn't have time to add it may a default per-user file be
7040 placed in <file>/etc/skel</file>.
7044 <file>/etc/skel</file> should be as empty as we can make it.
7045 This is particularly true because there is no easy (or
7046 necessarily desirable) mechanism for ensuring that the
7047 appropriate dotfiles are copied into the accounts of
7048 existing users when a package is installed.
7054 <heading>Log files</heading>
7056 Log files should usually be named
7057 <file>/var/log/<var>package</var>.log</file>. If you have many
7058 log files, or need a separate directory for permission
7059 reasons (<file>/var/log</file> is writable only by
7060 <file>root</file>), you should usually create a directory named
7061 <file>/var/log/<var>package</var></file> and place your log
7066 Log files must be rotated occasionally so that they don't
7067 grow indefinitely; the best way to do this is to drop a log
7068 rotation configuration file into the directory
7069 <file>/etc/logrotate.d</file> and use the facilities provided by
7070 logrotate.<footnote>
7072 The traditional approach to log files has been to set up
7073 <em>ad hoc</em> log rotation schemes using simple shell
7074 scripts and cron. While this approach is highly
7075 customizable, it requires quite a lot of sysadmin work.
7076 Even though the original Debian system helped a little
7077 by automatically installing a system which can be used
7078 as a template, this was deemed not enough.
7082 The use of <prgn>logrotate</prgn>, a program developed
7083 by Red Hat, is better, as it centralizes log management.
7084 It has both a configuration file
7085 (<file>/etc/logrotate.conf</file>) and a directory where
7086 packages can drop their individual log rotation
7087 configurations (<file>/etc/logrotate.d</file>).
7090 Here is a good example for a logrotate config
7091 file (for more information see <manref name="logrotate"
7093 <example compact="compact">
7094 /var/log/foo/*.log {
7099 /etc/init.d/foo force-reload
7103 This rotates all files under <file>/var/log/foo</file>, saves 12
7104 compressed generations, and forces the daemon to reload its
7105 configuration information after the log rotation.
7109 Log files should be removed when the package is
7110 purged (but not when it is only removed). This should be
7111 done by the <prgn>postrm</prgn> script when it is called
7112 with the argument <tt>purge</tt> (see <ref
7113 id="removedetails">).
7118 <heading>Permissions and owners</heading>
7121 The rules in this section are guidelines for general use.
7122 If necessary you may deviate from the details below.
7123 However, if you do so you must make sure that what is done
7124 is secure and you should try to be as consistent as possible
7125 with the rest of the system. You should probably also
7126 discuss it on <prgn>debian-devel</prgn> first.
7130 Files should be owned by <tt>root.root</tt>, and made
7131 writable only by the owner and universally readable (and
7132 executable, if appropriate), that is mode 644 or 755.
7136 Directories should be mode 755 or (for group-writability)
7137 mode 2775. The ownership of the directory should be
7138 consistent with its mode: if a directory is mode 2775, it
7139 should be owned by the group that needs write access to
7144 Setuid and setgid executables should be mode 4755 or 2755
7145 respectively, and owned by the appropriate user or group.
7146 They should not be made unreadable (modes like 4711 or
7147 2711 or even 4111); doing so achieves no extra security,
7148 because anyone can find the binary in the freely available
7149 Debian package; it is merely inconvenient. For the same
7150 reason you should not restrict read or execute permissions
7151 on non-set-id executables.
7155 Some setuid programs need to be restricted to particular
7156 sets of users, using file permissions. In this case they
7157 should be owned by the uid to which they are set-id, and by
7158 the group which should be allowed to execute them. They
7159 should have mode 4754; again there is no point in making
7160 them unreadable to those users who must not be allowed to
7165 It is possible to arrange that the system administrator can
7166 reconfigure the package to correspond to their local
7167 security policy by changing the permissions on a binary:
7168 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7169 described below.<footnote>
7170 Ordinary files installed by <prgn>dpkg</prgn> (as
7171 opposed to <tt>conffile</tt>s and other similar objects)
7172 normally have their permissions reset to the distributed
7173 permissions when the package is reinstalled. However,
7174 the use of <prgn>dpkg-statoverride</prgn> overrides this
7175 default behaviour. If you use this method, you should
7176 remember to describe <prgn>dpkg-statoverride</prgn> in
7177 the package documentation; being a relatively new
7178 addition to Debian, it is probably not yet well-known.
7180 Another method you should consider is to create a group for
7181 people allowed to use the program(s) and make any setuid
7182 executables executable only by that group.
7186 If you need to create a new user or group for your package
7187 there are two possibilities. Firstly, you may need to
7188 make some files in the binary package be owned by this
7189 user or group, or you may need to compile the user or
7190 group id (rather than just the name) into the binary
7191 (though this latter should be avoided if possible, as in
7192 this case you need a statically allocated id).</p>
7195 If you need a statically allocated id, you must ask for a
7196 user or group id from the <tt>base-passwd</tt> maintainer,
7197 and must not release the package until you have been
7198 allocated one. Once you have been allocated one you must
7199 either make the package depend on a version of the
7200 <tt>base-passwd</tt> package with the id present in
7201 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7202 your package to create the user or group itself with the
7203 correct id (using <tt>adduser</tt>) in its
7204 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7205 the <prgn>postinst</prgn> is to be preferred if it is
7206 possible, otherwise a pre-dependency will be needed on the
7207 <tt>adduser</tt> package.)
7211 On the other hand, the program might be able to determine
7212 the uid or gid from the user or group name at runtime, so
7213 that a dynamically allocated id can be used. In this case
7214 you should choose an appropriate user or group name,
7215 discussing this on <prgn>debian-devel</prgn> and checking
7216 with the <package/base-passwd/ maintainer that it is unique and that
7217 they do not wish you to use a statically allocated id
7218 instead. When this has been checked you must arrange for
7219 your package to create the user or group if necessary using
7220 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7221 <prgn>postinst</prgn> script (again, the latter is to be
7222 preferred if it is possible).
7226 Note that changing the numeric value of an id associated
7227 with a name is very difficult, and involves searching the
7228 file system for all appropriate files. You need to think
7229 carefully whether a static or dynamic id is required, since
7230 changing your mind later will cause problems.
7233 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7235 This section is not intended as policy, but as a
7236 description of the use of <prgn>dpkg-statoverride</prgn>.
7240 <prgn>dpkg-statoverride</prgn> is a replacement for the
7241 deprecated <tt>suidmanager</tt> package. Packages which
7242 previously used <tt>suidmanager</tt> should have a
7243 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7244 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7245 and <tt>suidunregister</tt> should now be simply removed
7246 from the maintainer scripts.
7250 If a system administrator wishes to have a file (or
7251 directory or other such thing) installed with owner and
7252 permissions different from those in the distributed Debian
7253 package, they can use the <prgn>dpkg-statoverride</prgn>
7254 program to instruct <prgn>dpkg</prgn> to use the different
7255 settings every time the file is installed. Thus the
7256 package maintainer should distribute the files with their
7257 normal permissions, and leave it for the system
7258 administrator to make any desired changes. For example, a
7259 daemon which is normally required to be setuid root, but
7260 in certain situations could be used without being setuid,
7261 should be installed setuid in the <tt>.deb</tt>. Then the
7262 local system administrator can change this if they wish.
7263 If there are two standard ways of doing it, the package
7264 maintainer can use <tt>debconf</tt> to find out the
7265 preference, and call <prgn>dpkg-statoverride</prgn> in the
7266 maintainer script if necessary to accommodate the system
7267 administrator's choice.
7271 Given the above, <prgn>dpkg-statoverride</prgn> is
7272 essentially a tool for system administrators and would not
7273 normally be needed in the maintainer scripts. There is
7274 one type of situation, though, where calls to
7275 <prgn>dpkg-statoverride</prgn> would be needed in the
7276 maintainer scripts, and that involves packages which use
7277 dynamically allocated user or group ids. In such a
7278 situation, something like the following idiom can be very
7279 helpful in the package's <prgn>postinst</prgn>, where
7280 <tt>sysuser</tt> is a dynamically allocated id:
7282 for i in /usr/bin/foo /usr/sbin/bar
7284 if ! dpkg-statoverride --list $i >/dev/null
7286 dpkg-statoverride --update --add sysuser root 4755 $i
7290 The corresponding <tt>dpkg-statoverride --remove</tt>
7291 calls can then be made unconditionally when the package is
7299 <chapt id="customized-programs">
7300 <heading>Customized programs</heading>
7302 <sect id="arch-spec">
7303 <heading>Architecture specification strings</heading>
7306 If a program needs to specify an <em>architecture specification
7307 string</em> in some place, the following format should be
7308 used: <var>arch</var>-<var>os</var><footnote>
7309 The following architectures and operating systems are
7310 currently recognised by <prgn>dpkg-architecture</prgn>.
7311 The architecture, <tt><var>arch</var></tt>, is one of
7312 the following: <tt>alpha</tt>, <tt>arm</tt>,
7313 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7314 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7315 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7316 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7317 operating system, <tt><var>os</var></tt>, is one of:
7318 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7319 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7320 reserved for the GNU/Hurd operating system.
7325 Note that we don't want to use
7326 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7327 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7328 since this would make our programs incompatible with other
7329 Linux distributions. We also don't use something like
7330 <tt><var>arch</var>-unknown-linux</tt>, since the
7331 <tt>unknown</tt> does not look very good.
7336 <heading>Daemons</heading>
7339 The configuration files <file>/etc/services</file>,
7340 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7341 by the <prgn>netbase</prgn> package and must not be modified
7346 If a package requires a new entry in one of these files, the
7347 maintainer should get in contact with the
7348 <prgn>netbase</prgn> maintainer, who will add the entries
7349 and release a new version of the <prgn>netbase</prgn>
7354 The configuration file <file>/etc/inetd.conf</file> must not be
7355 modified by the package's scripts except via the
7356 <prgn>update-inetd</prgn> script or the
7357 <file>DebianNet.pm</file> Perl module. See their documentation
7358 for details on how to add entries.
7362 If a package wants to install an example entry into
7363 <file>/etc/inetd.conf</file>, the entry must be preceded with
7364 exactly one hash character (<tt>#</tt>). Such lines are
7365 treated as "commented out by user" by the
7366 <prgn>update-inetd</prgn> script and are not changed or
7367 activated during package updates.
7372 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7376 Some programs need to create pseudo-ttys. This should be done
7377 using Unix98 ptys if the C library supports it. The resulting
7378 program must not be installed setuid root, unless that
7379 is required for other functionality.
7383 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7384 <file>/var/log/lastlog</file> must be installed writeable by
7385 group <tt>utmp</tt>. Programs which need to modify those
7386 files must be installed setgid <tt>utmp</tt>.
7391 <heading>Editors and pagers</heading>
7394 Some programs have the ability to launch an editor or pager
7395 program to edit or display a text document. Since there are
7396 lots of different editors and pagers available in the Debian
7397 distribution, the system administrator and each user should
7398 have the possibility to choose their preferred editor and
7403 In addition, every program should choose a good default
7404 editor/pager if none is selected by the user or system
7409 Thus, every program that launches an editor or pager must
7410 use the EDITOR or PAGER environment variable to determine
7411 the editor or pager the user wishes to use. If these
7412 variables are not set, the programs <file>/usr/bin/editor</file>
7413 and <file>/usr/bin/pager</file> should be used, respectively.
7417 These two files are managed through the <prgn>dpkg</prgn>
7418 "alternatives" mechanism. Thus every package providing an
7419 editor or pager must call the
7420 <prgn>update-alternatives</prgn> script to register these
7425 If it is very hard to adapt a program to make use of the
7426 EDITOR or PAGER variables, that program may be configured to
7427 use <file>/usr/bin/sensible-editor</file> and
7428 <file>/usr/bin/sensible-pager</file> as the editor or pager
7429 program respectively. These are two scripts provided in the
7430 Debian base system that check the EDITOR and PAGER variables
7431 and launch the appropriate program, and fall back to
7432 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7433 variable is not set.
7437 A program may also use the VISUAL environment variable to
7438 determine the user's choice of editor. If it exists, it
7439 should take precedence over EDITOR. This is in fact what
7440 <file>/usr/bin/sensible-editor</file> does.
7444 It is not required for a package to depend on
7445 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7446 package to provide such virtual packages.<footnote>
7447 The Debian base system already provides an editor and a
7453 <sect id="web-appl">
7454 <heading>Web servers and applications</heading>
7457 This section describes the locations and URLs that should
7458 be used by all web servers and web applications in the
7465 Cgi-bin executable files are installed in the
7467 <example compact="compact">
7468 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7470 and should be referred to as
7471 <example compact="compact">
7472 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7477 <p>Access to HTML documents</p>
7480 HTML documents for a package are stored in
7481 <file>/usr/share/doc/<var>package</var></file>
7482 and can be referred to as
7483 <example compact="compact">
7484 http://localhost/doc/<var>package</var>/<var>filename</var>
7489 The web server should restrict access to the document
7490 tree so that only clients on the same host can read
7491 the documents. If the web server does not support such
7492 access controls, then it should not provide access at
7493 all, or ask about providing access during installation.
7498 <p>Web Document Root</p>
7501 Web Applications should try to avoid storing files in
7502 the Web Document Root. Instead they should use the
7503 /usr/share/doc/<var>package</var> directory for
7504 documents and register the Web Application via the
7505 <package>doc-base</package> package. If access to the
7506 web document root is unavoidable then use
7507 <example compact="compact">
7510 as the Document Root. This might be just a symbolic
7511 link to the location where the system administrator
7512 has put the real document root.
7520 <sect id="mail-transport-agents">
7521 <heading>Mail transport, delivery and user agents</heading>
7524 Debian packages which process electronic mail, whether mail
7525 user agents (MUAs) or mail transport agents (MTAs), must
7526 ensure that they are compatible with the configuration
7527 decisions below. Failure to do this may result in lost
7528 mail, broken <tt>From:</tt> lines, and other serious brain
7533 The mail spool is <file>/var/mail</file> and the interface to
7534 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7535 the FHS). On older systems, the mail spool may be
7536 physically located in <file>/var/spool/mail</file>, but all
7537 access to the mail spool should be via the
7538 <file>/var/mail</file> symlink. The mail spool is part of the
7539 base system and not part of the MTA package.
7543 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7544 programs (such as IMAP daemons) must lock the mailbox in an
7545 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7546 be combined with dot locking. To avoid deadlocks, a program
7547 should use <tt>fcntl()</tt> first and dot locking after
7548 this, or alternatively implement the two locking methods in
7549 a non blocking way<footnote>
7550 If it is not possible to establish both locks, the
7551 system shouldn't wait for the second lock to be
7552 established, but remove the first lock, wait a (random)
7553 time, and start over locking again.
7554 </footnote>. Using the functions <tt>maillock</tt> and
7555 <tt>mailunlock</tt> provided by the
7556 <tt>liblockfile*</tt><footnote>
7557 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7558 to use these functions.
7559 </footnote> packages is the recommended way to realize this.
7563 Mailboxes are generally mode 660
7564 <tt><var>user</var>.mail</tt> unless the system
7565 administrator has chosen otherwise. A MUA may remove a
7566 mailbox (unless it has nonstandard permissions) in which
7567 case the MTA or another MUA must recreate it if needed.
7568 Mailboxes must be writable by group mail.
7572 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7573 be setgid mail to do the locking mentioned above (and
7574 must obviously avoid accessing other users' mailboxes
7575 using this privilege).</p>
7578 <file>/etc/aliases</file> is the source file for the system mail
7579 aliases (e.g., postmaster, usenet, etc.), it is the one
7580 which the sysadmin and <prgn>postinst</prgn> scripts may
7581 edit. After <file>/etc/aliases</file> is edited the program or
7582 human editing it must call <prgn>newaliases</prgn>. All MTA
7583 packages must come with a <prgn>newaliases</prgn> program,
7584 even if it does nothing, but older MTA packages did not do
7585 this so programs should not fail if <prgn>newaliases</prgn>
7586 cannot be found. Note that because of this, all MTA
7587 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7588 <tt>Replaces: mail-transport-agent</tt> control file
7593 The convention of writing <tt>forward to
7594 <var>address</var></tt> in the mailbox itself is not
7595 supported. Use a <tt>.forward</tt> file instead.</p>
7598 The <prgn>rmail</prgn> program used by UUCP
7599 for incoming mail should be <file>/usr/sbin/rmail</file>.
7600 Likewise, <prgn>rsmtp</prgn>, for receiving
7601 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7605 If your package needs to know what hostname to use on (for
7606 example) outgoing news and mail messages which are generated
7607 locally, you should use the file <file>/etc/mailname</file>. It
7608 will contain the portion after the username and <tt>@</tt>
7609 (at) sign for email addresses of users on the machine
7610 (followed by a newline).
7614 Such package should check for the existence of this file
7615 when it is being configured. If it exists, it should be
7616 used without comment, although an MTA's configuration script
7617 may wish to prompt the user even if it finds that this file
7618 exists. If the file does not exist, the package should
7619 prompt the user for the value (preferably using
7620 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7621 as well as using it in the package's configuration. The
7622 prompt should make it clear that the name will not just be
7623 used by that package. For example, in this situation the
7624 <tt>inn</tt> package could say something like:
7625 <example compact="compact">
7626 Please enter the "mail name" of your system. This is the
7627 hostname portion of the address to be shown on outgoing
7628 news and mail messages. The default is
7629 <var>syshostname</var>, your system's host name. Mail
7630 name ["<var>syshostname</var>"]:
7632 where <var>syshostname</var> is the output of <tt>hostname
7638 <heading>News system configuration</heading>
7641 All the configuration files related to the NNTP (news)
7642 servers and clients should be located under
7643 <file>/etc/news</file>.</p>
7646 There are some configuration issues that apply to a number
7647 of news clients and server packages on the machine. These
7651 <tag><file>/etc/news/organization</file></tag>
7653 A string which should appear as the
7654 organization header for all messages posted
7655 by NNTP clients on the machine
7658 <tag><file>/etc/news/server</file></tag>
7660 Contains the FQDN of the upstream NNTP
7661 server, or localhost if the local machine is
7666 Other global files may be added as required for cross-package news
7673 <heading>Programs for the X Window System</heading>
7676 <heading>Providing X support and package priorities</heading>
7679 Programs that can be configured with support for the X
7680 Window System must be configured to do so and must declare
7681 any package dependencies necessary to satisfy their
7682 runtime requirements when using the X Window System. If
7683 such a package is of higher priority than the X packages
7684 on which it depends, it is required that either the
7685 X-specific components be split into a separate package, or
7686 that an alternative version of the package, which includes
7687 X support, be provided, or that the package's priority be
7693 <heading>Packages providing an X server</heading>
7696 Packages that provide an X server that, directly or
7697 indirectly, communicates with real input and display
7698 hardware should declare in their control data that they
7699 provide the virtual package <tt>xserver</tt>.<footnote>
7700 This implements current practice, and provides an
7701 actual policy for usage of the <tt>xserver</tt>
7702 virtual package which appears in the virtual packages
7703 list. In a nutshell, X servers that interface
7704 directly with the display and input hardware or via
7705 another subsystem (e.g., GGI) should provide
7706 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7707 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7713 <heading>Packages providing a terminal emulator</heading>
7716 Packages that provide a terminal emulator for the X Window
7717 System which meet the criteria listed below should declare
7718 in their control data that they provide the virtual
7719 package <tt>x-terminal-emulator</tt>. They should also
7720 register themselves as an alternative for
7721 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7726 To be an <tt>x-terminal-emulator</tt>, a program must:
7727 <list compact="compact">
7729 Be able to emulate a DEC VT100 terminal, or a
7730 compatible terminal.
7734 Support the command-line option <tt>-e
7735 <var>command</var></tt>, which creates a new
7736 terminal window<footnote>
7737 "New terminal window" does not necessarily mean
7738 a new top-level X window directly parented by
7739 the window manager; it could, if the terminal
7740 emulator application were so coded, be a new
7741 "view" in a multiple-document interface (MDI).
7743 and runs the specified <var>command</var>,
7744 interpreting the entirity of the rest of the command
7745 line as a command to pass straight to exec, in the
7746 manner that <tt>xterm</tt> does.
7750 Support the command-line option <tt>-T
7751 <var>title</var></tt>, which creates a new terminal
7752 window with the window title <var>title</var>.
7759 <heading>Packages providing a window manager</heading>
7762 Packages that provide a window manager should declare in
7763 their control data that they provide the virtual package
7764 <tt>x-window-manager</tt>. They should also register
7765 themselves as an alternative for
7766 <file>/usr/bin/x-window-manager</file>, with a priority
7767 calculated as follows:
7768 <list compact="compact">
7770 Start with a priority of 20.
7774 If the window manager supports the Debian menu
7775 system, add 20 points if this support is available
7776 in the package's default configuration (i.e., no
7777 configuration files belonging to the system or user
7778 have to be edited to activate the feature); if
7779 configuration files must be modified, add only 10
7785 If the window manager complies with <url
7786 id="http://www.freedesktop.org/Standards/wm-spec"
7787 name="The Window Manager Specification Project">,
7788 written by the <url id="http://www.freedesktop.org/"
7789 name="Free Desktop Group">, add 40 points.
7793 If the window manager permits the X session to be
7794 restarted using a <em>different</em> window manager
7795 (without killing the X server) in its default
7796 configuration, add 10 points; otherwise add none.
7803 <heading>Packages providing fonts</heading>
7806 Packages that provide fonts for the X Window
7808 For the purposes of Debian Policy, a "font for the X
7809 Window System" is one which is accessed via X protocol
7810 requests. Fonts for the Linux console, for PostScript
7811 renderers, or any other purpose, do not fit this
7812 definition. Any tool which makes such fonts available
7813 to the X Window System, however, must abide by this
7816 must do a number of things to ensure that they are both
7817 available without modification of the X or font server
7818 configuration, and that they do not corrupt files used by
7819 other font packages to register information about
7823 Fonts of any type supported by the X Window System
7824 must be in a separate binary package from any
7825 executables, libraries, or documentation (except
7826 that specific to the fonts shipped, such as their
7827 license information). If one or more of the fonts
7828 so packaged are necessary for proper operation of
7829 the package with which they are associated the font
7830 package may be Recommended; if the fonts merely
7831 provide an enhancement, a Suggests relationship may
7832 be used. Packages must not Depend on font
7834 This is because the X server may retrieve fonts
7835 from the local filesystem or over the network
7836 from an X font server; the Debian package system
7837 is empowered to deal only with the local
7843 BDF fonts must be converted to PCF fonts with the
7844 <prgn>bdftopcf</prgn> utility (available in the
7845 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7846 placed in a directory that corresponds to their
7848 <list compact="compact">
7850 100 dpi fonts must be placed in
7851 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7855 75 dpi fonts must be placed in
7856 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7860 Character-cell fonts, cursor fonts, and other
7861 low-resolution fonts must be placed in
7862 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7868 Speedo fonts must be placed in
7869 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7873 Type 1 fonts must be placed in
7874 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7875 metric files are available, they must be placed here
7880 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7881 other than those listed above must be neither
7882 created nor used. (The <file>PEX</file>, <file>CID</file>,
7883 and <file>cyrillic</file> directories are excepted for
7884 historical reasons, but installation of files into
7885 these directories remains discouraged.)
7889 Font packages may, instead of placing files directly
7890 in the X font directories listed above, provide
7891 symbolic links in that font directory pointing to
7892 the files' actual location in the filesystem. Such
7893 a location must comply with the FHS.
7897 Font packages should not contain both 75dpi and
7898 100dpi versions of a font. If both are available,
7899 they should be provided in separate binary packages
7900 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7901 the names of the packages containing the
7902 corresponding fonts.
7906 Fonts destined for the <file>misc</file> subdirectory
7907 should not be included in the same package as 75dpi
7908 or 100dpi fonts; instead, they should be provided in
7909 a separate package with <tt>-misc</tt> appended to
7914 Font packages must not provide the files
7915 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7916 <file>fonts.scale</file> in a font directory:
7919 <file>fonts.dir</file> files must not be provided at all.
7923 <file>fonts.alias</file> and <file>fonts.scale</file>
7924 files, if needed, should be provided in the
7926 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7927 where <var>fontdir</var> is the name of the
7929 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7930 package's corresponding fonts are stored
7931 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7932 <var>package</var> is the name of the package
7933 that provides these fonts, and
7934 <var>extension</var> is either <tt>scale</tt>
7935 or <tt>alias</tt>, whichever corresponds to
7942 Font packages must declare a dependency on
7943 <tt>xutils (>> 4.0.3)</tt> in their control
7948 Font packages that provide one or more
7949 <file>fonts.scale</file> files as described above must
7950 invoke <prgn>update-fonts-scale</prgn> on each
7951 directory into which they installed fonts
7952 <em>before</em> invoking
7953 <prgn>update-fonts-dir</prgn> on that directory.
7954 This invocation must occur in both the
7955 <prgn>postinst</prgn> (for all arguments) and
7956 <prgn>postrm</prgn> (for all arguments except
7957 <tt>upgrade</tt>) scripts.
7961 Font packages that provide one or more
7962 <file>fonts.alias</file> files as described above must
7963 invoke <prgn>update-fonts-alias</prgn> on each
7964 directory into which they installed fonts. This
7965 invocation must occur in both the
7966 <prgn>postinst</prgn> (for all arguments) and
7967 <prgn>postrm</prgn> (for all arguments except
7968 <tt>upgrade</tt>) scripts.
7972 Font packages must invoke
7973 <prgn>update-fonts-dir</prgn> on each directory into
7974 which they installed fonts. This invocation must
7975 occur in both the <prgn>postinst</prgn> (for all
7976 arguments) and <prgn>postrm</prgn> (for all
7977 arguments except <tt>upgrade</tt>) scripts.
7981 Font packages must not provide alias names for the
7982 fonts they include which collide with alias names
7983 already in use by fonts already packaged.
7987 Font packages must not provide fonts with the same
7988 XLFD registry name as another font already packaged.
7995 <heading>Application defaults files</heading>
7998 Application defaults files must be installed in the
7999 directory <file>/etc/X11/app-defaults/</file> (use of a
8000 localized subdirectory of <file>/etc/X11/</file> as described
8001 in the <em>X Toolkit Intrinsics - C Language
8002 Interface</em> manual is also permitted). They must be
8003 registered as <tt>conffile</tt>s or handled as
8004 configuration files. Packages must not provide the
8005 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
8009 Customization of programs' X resources may also be
8010 supported with the provision of a file with the same name
8011 as that of the package placed in the
8012 <file>/etc/X11/Xresources/</file> directory, which must
8013 registered as a <tt>conffile</tt> or handled as a
8014 configuration file.<footnote>
8015 Note that this mechanism is not the same as using
8016 app-defaults; app-defaults are tied to the client
8017 binary on the local filesystem, whereas X resources
8018 are stored in the X server and affect all connecting
8021 <em>Important:</em> packages that install files into the
8022 <file>/etc/X11/Xresources/</file> directory must conflict with
8023 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
8024 it is possible for the installing package to destroy a
8025 previously-existing <file>/etc/X11/Xresources</file> file
8026 which had been customized by the system administrator.
8031 <heading>Installation directory issues</heading>
8034 Packages using the X Window System should not be
8035 configured to install files under the <file>/usr/X11R6/</file>
8036 directory unless they use <prgn>imake</prgn>. The
8037 <file>/usr/X11R6/</file> directory hierarchy should be
8038 regarded as deprecated for all packages except the X
8039 Window System itself, and those which use the
8040 <prgn>imake</prgn> program it provides, in which case the
8041 packages may transition out of the <file>/usr/X11R6/</file>
8042 directory at the maintainer's discretion.<footnote>
8043 <prgn>Imake</prgn>-using programs are exempt because,
8044 as long as they are written correctly, the pathnames
8045 they use to locate resources and install themselves
8046 are derived wholly from the X Window System
8047 configuration. Thus, in the event that the X Window
8048 System moves to <file>/usr/X11R7/</file>,
8049 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
8050 that is required for these programs is a recompile
8051 against the corresponding X Window System library
8052 development packages.
8057 Programs that use GNU <prgn>autoconf</prgn> and
8058 <prgn>automake</prgn> are usually easily configured at
8059 compile time to use <file>/usr/</file> instead of
8060 <file>/usr/X11R6/</file>, and this should be done whenever
8061 possible. Configuration files for window managers and
8062 display managers should be placed in a subdirectory of
8063 <file>/etc/X11/</file> corresponding to the package name due
8064 to these programs' tight integration with the mechanisms
8065 of the X Window System. Application-level programs should
8066 use the <file>/etc/</file> directory unless otherwise mandated
8071 The installation of files into subdirectories
8072 of <file>/usr/X11R6/include/X11/</file> and
8073 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8074 package maintainers should determine if subdirectories of
8075 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8076 instead. (The use of symbolic links from the
8077 <file>X11R6</file> directories to other FHS-compliant
8078 locations is encouraged if the program is not easily
8079 configured to look elsewhere for its files.)
8083 Packages must not provide or install files into the directories
8084 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8085 <file>/usr/lib/X11/</file>. Files within a package should,
8086 however, make reference to these directories, rather than
8087 their <tt>X11R6</tt>-named counterparts
8088 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8089 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8090 referred to have not been moved to other FHS-compliant
8096 <heading>The OSF/Motif and OpenMotif libraries</heading>
8099 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8100 OpenMotif libraries</em><footnote>
8101 OSF/Motif and OpenMotif are collectively referred to as
8102 "Motif" in this policy document.
8104 should be compiled against and tested with LessTif (a free
8105 re-implementation of Motif) instead. If the maintainer
8106 judges that the program or programs do not work
8107 sufficiently well with LessTif to be distributed and
8108 supported, but do so when compiled against Motif, then two
8109 versions of the package should be created; one linked
8110 statically against Motif and with <tt>-smotif</tt>
8111 appended to the package name, and one linked dynamically
8112 against Motif and with <tt>-dmotif</tt> appended to the
8117 Both Motif-linked versions are dependent
8118 upon non-DFSG-compliant software and thus cannot be
8119 uploaded to the <em>main</em> distribution; if the
8120 software is itself DFSG-compliant it may be uploaded to
8121 the <em>contrib</em> distribution. While known existing
8122 versions of Motif permit unlimited redistribution of
8123 binaries linked against the library (whether statically or
8124 dynamically), it is the package maintainer's
8125 responsibility to determine whether this is permitted by
8126 the license of the copy of Motif in their possession.
8132 <heading>Perl programs and modules</heading>
8135 Perl programs and modules should follow the current Perl policy.
8139 The Perl policy can be found in the <tt>perl-policy</tt>
8140 files in the <tt>debian-policy</tt> package.
8141 It is also available from the Debian web mirrors at
8142 <tt><url name="/doc/packaging-manuals/perl-policy/"
8143 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8148 <heading>Emacs lisp programs</heading>
8151 Please refer to the "Debian Emacs Policy" for details of how to
8152 package emacs lisp programs.
8156 The Emacs policy is available in
8157 <file>debian-emacs-policy.gz</file> of the
8158 <package>emacsen-common</package> package.
8159 It is also available from the Debian web mirrors at
8160 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8161 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8166 <heading>Games</heading>
8169 The permissions on <file>/var/games</file> are mode 755, owner
8170 <tt>root</tt> and group <tt>root</tt>.
8174 Each game decides on its own security policy.</p>
8177 Games which require protected, privileged access to
8178 high-score files, savegames, etc., may be made
8179 set-<em>group</em>-id (mode 2755) and owned by
8180 <tt>root.games</tt>, and use files and directories with
8181 appropriate permissions (770 <tt>root.games</tt>, for
8182 example). They must not be made
8183 set-<em>user</em>-id, as this causes security problems. (If
8184 an attacker can subvert any set-user-id game they can
8185 overwrite the executable of any other, causing other players
8186 of these games to run a Trojan horse program. With a
8187 set-group-id game the attacker only gets access to less
8188 important game data, and if they can get at the other
8189 players' accounts at all it will take considerably more
8193 Some packages, for example some fortune cookie programs, are
8194 configured by the upstream authors to install with their
8195 data files or other static information made unreadable so
8196 that they can only be accessed through set-id programs
8197 provided. You should not do this in a Debian package: anyone can
8198 download the <file>.deb</file> file and read the data from it,
8199 so there is no point making the files unreadable. Not
8200 making the files unreadable also means that you don't have
8201 to make so many programs set-id, which reduces the risk of a
8205 As described in the FHS, binaries of games should be
8206 installed in the directory <file>/usr/games</file>. This also
8207 applies to games that use the X Window System. Manual pages
8208 for games (X and non-X games) should be installed in
8209 <file>/usr/share/man/man6</file>.</p>
8215 <heading>Documentation</heading>
8218 <heading>Manual pages</heading>
8221 You should install manual pages in <prgn>nroff</prgn> source
8222 form, in appropriate places under <file>/usr/share/man</file>.
8223 You should only use sections 1 to 9 (see the FHS for more
8224 details). You must not install a preformatted "cat page".
8228 Each program, utility, and function should have an
8229 associated manual page included in the same package. It is
8230 suggested that all configuration files also have a manual
8231 page included as well. Manual pages for protocols and other
8232 auxiliary things are optional.
8236 If no manual page is available, this is considered as a bug
8237 and should be reported to the Debian Bug Tracking System (the
8238 maintainer of the package is allowed to write this bug report
8239 themselves, if they so desire). Do not close the bug report
8240 until a proper man page is available.<footnote>
8241 It is not very hard to write a man page. See the
8242 <url id="http://www.schweikhardt.net/man_page_howto.html"
8243 name="Man-Page-HOWTO">,
8244 <manref name="man" section="7">, the examples
8245 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8246 the helper programs <prgn>help2man</prgn>, or the
8247 directory <file>/usr/share/doc/man-db/examples</file>.
8252 You may forward a complaint about a missing man page to the
8253 upstream authors, and mark the bug as forwarded in the
8254 Debian bug tracking system. Even though the GNU Project do
8255 not in general consider the lack of a man page to be a bug,
8256 we do; if they tell you that they don't consider it a bug
8257 you should leave the bug in our bug tracking system open
8262 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8266 If one man page needs to be accessible via several names it
8267 is better to use a symbolic link than the <file>.so</file>
8268 feature, but there is no need to fiddle with the relevant
8269 parts of the upstream source to change from <file>.so</file> to
8270 symlinks: don't do it unless it's easy. You should not
8271 create hard links in the manual page directories, nor put
8272 absolute filenames in <file>.so</file> directives. The filename
8273 in a <file>.so</file> in a man page should be relative to the
8274 base of the man page tree (usually
8275 <file>/usr/share/man</file>). If you do not create any links
8276 (whether symlinks, hard links, or <tt>.so</tt> directives)
8277 in the filesystem to the alternate names of the man page,
8278 then you should not rely on <prgn>man</prgn> finding your
8279 man page under those names based solely on the information in
8280 the man page's header.<footnote>
8281 Supporting this in <prgn>man</prgn> often requires
8282 unreasonable processing time to find a manual page or to
8283 report that none exists, and moves knowledge into man's
8284 database that would be better left in the filesystem.
8285 This support is therefore deprecated and will cease to
8286 be present in the future.
8292 <heading>Info documents</heading>
8295 Info documents should be installed in <file>/usr/share/info</file>.
8296 They should be compressed with <tt>gzip -9</tt>.
8300 Your package should call <prgn>install-info</prgn> to update
8301 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8302 script when called with a <tt>configure</tt> argument, for
8304 <example compact="compact">
8305 install-info --quiet --section Development Development \
8306 /usr/share/info/foobar.info
8310 It is a good idea to specify a section for the location of
8311 your program; this is done with the <tt>--section</tt>
8312 switch. To determine which section to use, you should look
8313 at <file>/usr/share/info/dir</file> on your system and choose the most
8314 relevant (or create a new section if none of the current
8315 sections are relevant). Note that the <tt>--section</tt>
8316 flag takes two arguments; the first is a regular expression
8317 to match (case-insensitively) against an existing section,
8318 the second is used when creating a new one.</p>
8321 You should remove the entries in the <prgn>prerm</prgn>
8322 script when called with a <tt>remove</tt> argument:
8323 <example compact="compact">
8324 install-info --quiet --remove /usr/share/info/foobar.info
8328 If <prgn>install-info</prgn> cannot find a description entry
8329 in the Info file you must supply one. See <manref
8330 name="install-info" section="8"> for details.</p>
8334 <heading>Additional documentation</heading>
8337 Any additional documentation that comes with the package may
8338 be installed at the discretion of the package maintainer.
8339 Text documentation should be installed in the directory
8340 <file>/usr/share/doc/<var>package</var></file>, where
8341 <var>package</var> is the name of the package, and
8342 compressed with <tt>gzip -9</tt> unless it is small.
8346 If a package comes with large amounts of documentation which
8347 many users of the package will not require you should create
8348 a separate binary package to contain it, so that it does not
8349 take up disk space on the machines of users who do not need
8350 or want it installed.</p>
8353 It is often a good idea to put text information files
8354 (<file>README</file>s, changelogs, and so forth) that come with
8355 the source package in <file>/usr/share/doc/<var>package</var></file>
8356 in the binary package. However, you don't need to install
8357 the instructions for building and installing the package, of
8361 Packages must not require the existence of any files in
8362 <file>/usr/share/doc/</file> in order to function
8364 The system administrator should be able to
8365 delete files in <file>/usr/share/doc/</file> without causing
8366 any programs to break.
8368 Any files that are referenced by programs but are also
8369 useful as standalone documentation should be installed under
8370 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8371 <file>/usr/share/doc/<var>package</var></file>.
8375 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8376 link to another directory in <file>/usr/share/doc</file> only if
8377 the two packages both come from the same source and the
8378 first package Depends on the second.<footnote>
8380 Please note that this does not override the section on
8381 changelog files below, so the file
8382 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8383 must refer to the changelog for the current version of
8384 <var>package</var> in question. In practice, this means
8385 that the sources of the target and the destnation of the
8386 symlink must be the same (same source package and
8393 Former Debian releases placed all additional documentation
8394 in <file>/usr/doc/<var>package</var></file>. This has been
8395 changed to <file>/usr/share/doc/<var>package</var></file>,
8396 and packages must not put documentation in the directory
8397 <file>/usr/doc/<var>package</var></file>. <footnote>
8398 At this phase of the transition, we no longer require a
8399 symbolic link in <file>/usr/doc/</file>. At a later point,
8400 policy shall change to make the symbolic links a bug.
8406 <heading>Preferred documentation formats</heading>
8409 The unification of Debian documentation is being carried out
8413 If your package comes with extensive documentation in a
8414 markup format that can be converted to various other formats
8415 you should if possible ship HTML versions in a binary
8416 package, in the directory
8417 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8418 its subdirectories.<footnote>
8419 The rationale: The important thing here is that HTML
8420 docs should be available in <em>some</em> package, not
8421 necessarily in the main binary package.
8426 Other formats such as PostScript may be provided at the
8427 package maintainer's discretion.
8431 <sect id="copyrightfile">
8432 <heading>Copyright information</heading>
8435 Every package must be accompanied by a verbatim copy of its
8436 copyright and distribution license in the file
8437 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8438 file must neither be compressed nor be a symbolic link.
8442 In addition, the copyright file must say where the upstream
8443 sources (if any) were obtained. It should name the original
8444 authors of the package and the Debian maintainer(s) who were
8445 involved with its creation.</p>
8448 A copy of the file which will be installed in
8449 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8450 be in <file>debian/copyright</file> in the source package.
8454 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8455 link to another directory in <file>/usr/share/doc</file> only if
8456 the two packages both come from the same source and the
8457 first package Depends on the second. These rules are
8458 important because copyrights must be extractable by
8463 Packages distributed under the UCB BSD license, the Artistic
8464 license, the GNU GPL, and the GNU LGPL should refer to the
8465 files <file>/usr/share/common-licenses/BSD</file>,
8466 <file>/usr/share/common-licenses/Artistic</file>,
8467 <file>/usr/share/common-licenses/GPL</file>, and
8468 <file>/usr/share/common-licenses/LGPL</file> respectively,
8469 rather than quoting them in the copyright file.
8473 You should not use the copyright file as a general <file>README</file>
8474 file. If your package has such a file it should be
8475 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8476 <file>README.Debian</file> or some other appropriate place.</p>
8480 <heading>Examples</heading>
8483 Any examples (configurations, source files, whatever),
8484 should be installed in a directory
8485 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8486 files should not be referenced by any program: they're there
8487 for the benefit of the system administrator and users as
8488 documentation only. Architecture-specific example files
8489 should be installed in a directory
8490 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8492 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8493 latter directory itself may be a symbolic link to the
8498 If the purpose of a package is to provide examples, then the
8499 example files may be installed into
8500 <file>/usr/share/doc/<var>package</var></file>.
8504 <sect id="changelogs">
8505 <heading>Changelog files</heading>
8508 Packages that are not Debian-native must contain a
8509 compressed copy of the <file>debian/changelog</file> file from
8510 the Debian source tree in
8511 <file>/usr/share/doc/<var>package</var></file> with the name
8512 <file>changelog.Debian.gz</file>.
8516 If an upstream changelog is available, it should be accessible as
8517 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8518 plain text. If the upstream changelog is distributed in
8519 HTML, it should be made available in that form as
8520 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8521 and a plain text <file>changelog.gz</file> should be generated
8522 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8523 the upstream changelog files do not already conform to this
8524 naming convention, then this may be achieved either by
8525 renaming the files, or by adding a symbolic link, at the
8526 maintainer's discretion.<footnote>
8527 Rationale: People should not have to look in places for
8528 upstream changelogs merely because they are given
8529 different names or are distributed in HTML format.
8534 All of these files should be installed compressed using
8535 <tt>gzip -9</tt>, as they will become large with time even
8536 if they start out small.
8540 If the package has only one changelog which is used both as
8541 the Debian changelog and the upstream one because there is
8542 no separate upstream maintainer then that changelog should
8543 usually be installed as
8544 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8545 there is a separate upstream maintainer, but no upstream
8546 changelog, then the Debian changelog should still be called
8547 <file>changelog.Debian.gz</file>.
8551 For details about the format and contents of the Debian
8552 changelog file, please see <ref id="dpkgchangelog">.
8557 <appendix id="pkg-scope">
8558 <heading>Introduction and scope of these appendices</heading>
8561 These appendices are taken essentially verbatim from the
8562 now-deprecated Packaging Manual, version 3.2.1.0. They are
8563 the chapters which are likely to be of use to package
8564 maintainers and which have not already been included in the
8565 policy document itself. Most of these sections are very likely
8566 not relevant to policy; they should be treated as
8567 documentation for the packaging system. Please note that these
8568 appendices are included for convenience, and for historical
8569 reasons: they used to be part of policy package, and they have
8570 not yet been incorporated into dpkg documentation. However,
8571 they still have value, and hence they are presented here.
8575 They have not yet been checked to ensure that they are
8576 compatible with the contents of policy, and if there are any
8577 contradictions, the version in the main policy document takes
8578 precedence. The remaining chapters of the old Packaging
8579 Manual have also not been read in detail to ensure that there
8580 are not parts which have been left out. Both of these will be
8585 Certain parts of the Packaging manual were integrated into the
8586 Policy Manual proper, and removed from the appendices. Links
8587 have been placed from the old locations to the new ones.
8591 <prgn>dpkg</prgn> is a suite of programs for creating binary
8592 package files and installing and removing them on Unix
8594 <prgn>dpkg</prgn> is targetted primarily at Debian
8595 GNU/Linux, but may work on or be ported to other
8601 The binary packages are designed for the management of
8602 installed executable programs (usually compiled binaries) and
8603 their associated data, though source code examples and
8604 documentation are provided as part of some packages.</p>
8607 This manual describes the technical aspects of creating Debian
8608 binary packages (<file>.deb</file> files). It documents the
8609 behaviour of the package management programs
8610 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8611 they interact with packages.</p>
8614 It also documents the interaction between
8615 <prgn>dselect</prgn>'s core and the access method scripts it
8616 uses to actually install the selected packages, and describes
8617 how to create a new access method.</p>
8620 This manual does not go into detail about the options and
8621 usage of the package building and installation tools. It
8622 should therefore be read in conjuction with those programs'
8627 The utility programs which are provided with <prgn>dpkg</prgn>
8628 for managing various system configuration and similar issues,
8629 such as <prgn>update-rc.d</prgn> and
8630 <prgn>install-info</prgn>, are not described in detail here -
8631 please see their man pages.
8635 It is assumed that the reader is reasonably familiar with the
8636 <prgn>dpkg</prgn> System Administrators' manual.
8637 Unfortunately this manual does not yet exist.
8641 The Debian version of the FSF's GNU hello program is provided
8642 as an example for people wishing to create Debian
8643 packages. The Debian <prgn>debmake</prgn> package is
8644 recommended as a very helpful tool in creating and maintaining
8645 Debian packages. However, while the tools and examples are
8646 helpful, they do not replace the need to read and follow the
8647 Policy and Programmer's Manual.</p>
8650 <appendix id="pkg-binarypkg">
8651 <heading>Binary packages (from old Packaging Manual)</heading>
8654 The binary package has two main sections. The first part
8655 consists of various control information files and scripts used
8656 by <prgn>dpkg</prgn> when installing and removing. See <ref
8657 id="pkg-controlarea">.
8661 The second part is an archive containing the files and
8662 directories to be installed.
8666 In the future binary packages may also contain other
8667 components, such as checksums and digital signatures. The
8668 format for the archive is described in full in the
8669 <file>deb(5)</file> man page.
8673 <sect id="pkg-bincreating"><heading>Creating package files -
8674 <prgn>dpkg-deb</prgn>
8678 All manipulation of binary package files is done by
8679 <prgn>dpkg-deb</prgn>; it's the only program that has
8680 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8681 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8682 will spot that the options requested are appropriate to
8683 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8688 In order to create a binary package you must make a
8689 directory tree which contains all the files and directories
8690 you want to have in the filesystem data part of the package.
8691 In Debian-format source packages this directory is usually
8692 <file>debian/tmp</file>, relative to the top of the package's
8697 They should have the locations (relative to the root of the
8698 directory tree you're constructing) ownerships and
8699 permissions which you want them to have on the system when
8704 With current versions of <prgn>dpkg</prgn> the uid/username
8705 and gid/groupname mappings for the users and groups being
8706 used should be the same on the system where the package is
8707 built and the one where it is installed.
8711 You need to add one special directory to the root of the
8712 miniature filesystem tree you're creating:
8713 <prgn>DEBIAN</prgn>. It should contain the control
8714 information files, notably the binary package control file
8715 (see <ref id="pkg-controlfile">).
8719 The <prgn>DEBIAN</prgn> directory will not appear in the
8720 filesystem archive of the package, and so won't be installed
8721 by <prgn>dpkg</prgn> when the package is installed.
8725 When you've prepared the package, you should invoke:
8727 dpkg --build <var>directory</var>
8732 This will build the package in
8733 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8734 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8735 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8740 See the man page <manref name="dpkg-deb" section="8"> for details of how
8741 to examine the contents of this newly-created file. You may find the
8742 output of following commands enlightening:
8744 dpkg-deb --info <var>filename</var>.deb
8745 dpkg-deb --contents <var>filename</var>.deb
8746 dpkg --contents <var>filename</var>.deb
8748 To view the copyright file for a package you could use this command:
8750 dpkg --fsys-tarfile <var>filename</var>.deb | tar xO ./usr/share/doc/\*/copyright | pager
8755 <sect id="pkg-controlarea">
8756 <heading>Package control information files</heading>
8759 The control information portion of a binary package is a
8760 collection of files with names known to <prgn>dpkg</prgn>.
8761 It will treat the contents of these files specially - some
8762 of them contain information used by <prgn>dpkg</prgn> when
8763 installing or removing the package; others are scripts which
8764 the package maintainer wants <prgn>dpkg</prgn> to run.
8768 It is possible to put other files in the package control
8769 area, but this is not generally a good idea (though they
8770 will largely be ignored).
8774 Here is a brief list of the control info files supported by
8775 <prgn>dpkg</prgn> and a summary of what they're used for.
8780 <tag><tt>control</tt>
8783 This is the key description file used by
8784 <prgn>dpkg</prgn>. It specifies the package's name
8785 and version, gives its description for the user,
8786 states its relationships with other packages, and so
8787 forth. See <ref id="sourcecontrolfiles"> and
8788 <ref id="binarycontrolfiles">.
8792 It is usually generated automatically from information
8793 in the source package by the
8794 <prgn>dpkg-gencontrol</prgn> program, and with
8795 assistance from <prgn>dpkg-shlibdeps</prgn>.
8796 See <ref id="pkg-sourcetools">.
8800 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8805 These are exectuable files (usually scripts) which
8806 <prgn>dpkg</prgn> runs during installation, upgrade
8807 and removal of packages. They allow the package to
8808 deal with matters which are particular to that package
8809 or require more complicated processing than that
8810 provided by <prgn>dpkg</prgn>. Details of when and
8811 how they are called are in <ref id="maintainerscripts">.
8815 It is very important to make these scripts idempotent.
8816 See <ref id="idempotency">.
8820 The maintainer scripts are guaranteed to run with a
8821 controlling terminal and can interact with the user.
8822 See <ref id="controllingterminal">.
8826 <tag><tt>conffiles</tt>
8829 This file contains a list of configuration files which
8830 are to be handled automatically by <prgn>dpkg</prgn>
8831 (see <ref id="pkg-conffiles">). Note that not necessarily
8832 every configuration file should be listed here.
8835 <tag><tt>shlibs</tt>
8838 This file contains a list of the shared libraries
8839 supplied by the package, with dependency details for
8840 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8841 when it determines what dependencies are required in a
8842 package control file. The <tt>shlibs</tt> file format
8843 is described on <ref id="shlibs">.
8848 <sect id="pkg-controlfile">
8849 <heading>The main control information file: <tt>control</tt></heading>
8852 The most important control information file used by
8853 <prgn>dpkg</prgn> when it installs a package is
8854 <tt>control</tt>. It contains all the package's "vital
8859 The binary package control files of packages built from
8860 Debian sources are made by a special tool,
8861 <prgn>dpkg-gencontrol</prgn>, which reads
8862 <file>debian/control</file> and <file>debian/changelog</file> to
8863 find the information it needs. See <ref id="pkg-sourcepkg"> for
8868 The fields in binary package control files are listed in
8869 <ref id="binarycontrolfiles">.
8873 A description of the syntax of control files and the purpose
8874 of the fields is available in <ref id="controlfields">.
8879 <heading>Time Stamps</heading>
8882 See <ref id="timestamps">.
8887 <appendix id="pkg-sourcepkg">
8888 <heading>Source packages (from old Packaging Manual) </heading>
8891 The Debian binary packages in the distribution are generated
8892 from Debian sources, which are in a special format to assist
8893 the easy and automatic building of binaries.
8896 <sect id="pkg-sourcetools">
8897 <heading>Tools for processing source packages</heading>
8900 Various tools are provided for manipulating source packages;
8901 they pack and unpack sources and help build of binary
8902 packages and help manage the distribution of new versions.
8906 They are introduced and typical uses described here; see
8907 <manref name="dpkg-source" section="1"> for full
8908 documentation about their arguments and operation.
8912 For examples of how to construct a Debian source package,
8913 and how to use those utilities that are used by Debian
8914 source packages, please see the <prgn>hello</prgn> example
8918 <sect1 id="pkg-dpkg-source">
8920 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8925 This program is frequently used by hand, and is also
8926 called from package-independent automated building scripts
8927 such as <prgn>dpkg-buildpackage</prgn>.
8931 To unpack a package it is typically invoked with
8933 dpkg-source -x <var>.../path/to/filename</var>.dsc
8938 with the <file><var>filename</var>.tar.gz</file> and
8939 <file><var>filename</var>.diff.gz</file> (if applicable) in
8940 the same directory. It unpacks into
8941 <file><var>package</var>-<var>version</var></file>, and if
8943 <file><var>package</var>-<var>version</var>.orig</file>, in
8944 the current directory.
8948 To create a packed source archive it is typically invoked:
8950 dpkg-source -b <var>package</var>-<var>version</var>
8955 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8956 <file>.diff.gz</file> (if appropriate) in the current
8957 directory. <prgn>dpkg-source</prgn> does not clean the
8958 source tree first - this must be done separately if it is
8963 See also <ref id="pkg-sourcearchives">.</p>
8967 <sect1 id="pkg-dpkg-buildpackage">
8969 <prgn>dpkg-buildpackage</prgn> - overall package-building
8974 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8975 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8976 targets <tt>clean</tt>, <tt>build</tt> and
8977 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8978 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
8979 source and binary package upload.
8983 It is usually invoked by hand from the top level of the
8984 built or unbuilt source directory. It may be invoked with
8985 no arguments; useful arguments include:
8986 <taglist compact="compact">
8987 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8990 Do not sign the <tt>.changes</tt> file or the
8991 source package <tt>.dsc</tt> file, respectively.</p>
8993 <tag><tt>-p<var>sign-command</var></tt></tag>
8996 Invoke <var>sign-command</var> instead of finding
8997 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
8998 <var>sign-command</var> must behave just like
8999 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9001 <tag><tt>-r<var>root-command</var></tt></tag>
9004 When root privilege is required, invoke the command
9005 <var>root-command</var>. <var>root-command</var>
9006 should invoke its first argument as a command, from
9007 the <prgn>PATH</prgn> if necessary, and pass its
9008 second and subsequent arguments to the command it
9009 calls. If no <var>root-command</var> is supplied
9010 then <var>dpkg-buildpackage</var> will take no
9011 special action to gain root privilege, so that for
9012 most packages it will have to be invoked as root to
9015 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9018 Two types of binary-only build and upload - see
9019 <manref name="dpkg-source" section="1">.
9026 <sect1 id="pkg-dpkg-gencontrol">
9028 <prgn>dpkg-gencontrol</prgn> - generates binary package
9033 This program is usually called from <file>debian/rules</file>
9034 (see <ref id="pkg-sourcetree">) in the top level of the source
9039 This is usually done just before the files and directories in the
9040 temporary directory tree where the package is being built have their
9041 permissions and ownerships set and the package is constructed using
9042 <prgn>dpkg-deb/</prgn>
9044 This is so that the control file which is produced has
9045 the right permissions
9050 <prgn>dpkg-gencontrol</prgn> must be called after all the
9051 files which are to go into the package have been placed in
9052 the temporary build directory, so that its calculation of
9053 the installed size of a package is correct.
9057 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9058 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9059 variable substitutions created by
9060 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9065 For a package which generates only one binary package, and
9066 which builds it in <file>debian/tmp</file> relative to the top
9067 of the source package, it is usually sufficient to call
9068 <prgn>dpkg-gencontrol</prgn>.
9072 Sources which build several binaries will typically need
9075 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9076 </example> The <tt>-P</tt> tells
9077 <prgn>dpkg-gencontrol</prgn> that the package is being
9078 built in a non-default directory, and the <tt>-p</tt>
9079 tells it which package's control file should be generated.
9083 <prgn>dpkg-gencontrol</prgn> also adds information to the
9084 list of files in <file>debian/files</file>, for the benefit of
9085 (for example) a future invocation of
9086 <prgn>dpkg-genchanges</prgn>.</p>
9089 <sect1 id="pkg-dpkg-shlibdeps">
9091 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9096 This program is usually called from <file>debian/rules</file>
9097 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9098 id="pkg-sourcetree">), in the top level of the source tree.
9102 Its arguments are executables.
9105 In a forthcoming dpkg version,
9106 <prgn>dpkg-shlibdeps</prgn> would be required to be
9107 called on shared libraries as well.
9110 They may be specified either in the locations in the
9111 source tree where they are created or in the locations
9112 in the temporary build tree where they are installed
9113 prior to binary package creation.
9115 </footnote> for which shared library dependencies should
9116 be included in the binary package's control file.
9120 If some of the found shared libraries should only
9121 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9122 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9123 by using the <tt>-d<var>dependency-field</var></tt> option
9124 before those executable(s). (Each <tt>-d</tt> option
9125 takes effect until the next <tt>-d</tt>.)
9129 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9130 output control file to be modified. Instead by default it
9131 adds to the <file>debian/substvars</file> file variable
9132 settings like <tt>shlibs:Depends</tt>. These variable
9133 settings must be referenced in dependency fields in the
9134 appropriate per-binary-package sections of the source
9139 For example, a package that generates an essential part
9140 which requires dependencies, and optional parts that
9141 which only require a recommendation, would separate those
9142 two sets of dependencies into two different fields.<footnote>
9143 At the time of writing, an example for this was the
9144 <package/xmms/ package, with Depends used for the xmms
9145 executable, Recommends for the plug-ins and Suggests for
9146 even more optional features provided by unzip.
9148 It can say in its <file>debian/rules</file>:
9150 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9151 -dRecommends <var>optionalpart anotheroptionalpart</var>
9153 and then in its main control file <file>debian/control</file>:
9156 Depends: ${shlibs:Pre-Depends}
9157 Recommends: ${shlibs:Recommends}
9163 Sources which produce several binary packages with
9164 different shared library dependency requirements can use
9165 the <tt>-p<var>varnameprefix</var></tt> option to override
9166 the default <tt>shlibs:</tt> prefix (one invocation of
9167 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9168 They can thus produce several sets of dependency
9169 variables, each of the form
9170 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9171 which can be referred to in the appropriate parts of the
9172 binary package control files.
9177 <sect1 id="pkg-dpkg-distaddfile">
9179 <prgn>dpkg-distaddfile</prgn> - adds a file to
9180 <file>debian/files</file>
9184 Some packages' uploads need to include files other than
9185 the source and binary package files.
9189 <prgn>dpkg-distaddfile</prgn> adds a file to the
9190 <file>debian/files</file> file so that it will be included in
9191 the <file>.changes</file> file when
9192 <prgn>dpkg-genchanges</prgn> is run.
9196 It is usually invoked from the <tt>binary</tt> target of
9197 <file>debian/rules</file>:
9199 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9201 The <var>filename</var> is relative to the directory where
9202 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9203 is usually the directory above the top level of the source
9204 tree. The <file>debian/rules</file> target should put the
9205 file there just before or just after calling
9206 <prgn>dpkg-distaddfile</prgn>.
9210 The <var>section</var> and <var>priority</var> are passed
9211 unchanged into the resulting <file>.changes</file> file.
9216 <sect1 id="pkg-dpkg-genchanges">
9218 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9223 This program is usually called by package-independent
9224 automatic building scripts such as
9225 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9230 It is usually called in the top level of a built source
9231 tree, and when invoked with no arguments will print out a
9232 straightforward <file>.changes</file> file based on the
9233 information in the source package's changelog and control
9234 file and the binary and source packages which should have
9240 <sect1 id="pkg-dpkg-parsechangelog">
9242 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9243 representation of a changelog
9247 This program is used internally by
9248 <prgn>dpkg-source</prgn> et al. It may also occasionally
9249 be useful in <file>debian/rules</file> and elsewhere. It
9250 parses a changelog, <file>debian/changelog</file> by default,
9251 and prints a control-file format representation of the
9252 information in it to standard output.
9256 <sect1 id="pkg-dpkg-architecture">
9258 <prgn>dpkg-architecture</prgn> - information about the build and
9263 This program can be used manually, but is also invoked by
9264 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9265 to set environment or make variables which specify the build and
9266 host architecture for the package building process.
9271 <sect id="pkg-sourcetree">
9272 <heading>The Debianised source tree</heading>
9275 The source archive scheme described later is intended to
9276 allow a Debianised source tree with some associated control
9277 information to be reproduced and transported easily. The
9278 Debianised source tree is a version of the original program
9279 with certain files added for the benefit of the
9280 Debianisation process, and with any other changes required
9281 made to the rest of the source code and installation
9286 The extra files created for Debian are in the subdirectory
9287 <file>debian</file> of the top level of the Debianised source
9288 tree. They are described below.
9291 <sect1 id="pkg-debianrules">
9292 <heading><file>debian/rules</file> - the main building script</heading>
9295 See <ref id="debianrules">.
9300 <sect1 id="pkg-dpkgchangelog">
9301 <heading><file>debian/changelog</file></heading>
9304 See <ref id="dpkgchangelog">.
9308 It is recommended that the entire changelog be encoded in the
9309 <url id="http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2279.html" name="UTF-8">
9311 <url id="http://www.unicode.org/"
9312 name="Unicode">.<footnote>
9314 Support for Unicode, and specifically UTF-8, is
9315 steadily increasing among popular applications in
9316 Debian. For example, in unstable, GNOME 2 has
9317 excellent support (almost level 2) in almost all its
9318 applications; the big remaining one is gnome-terminal,
9319 of which one requires development versions in order to
9320 support UTF-8 (available in Debian experimental now if
9321 you want to play). I think that by the time sarge is
9322 released, UTF-8 support will start to hit critical
9325 I think it is fairly obvious that we need to
9326 eventually transition to UTF-8 for our package
9327 infrastructure; it is really the only sane charset in
9328 an international environment. Now, we can't switch to
9329 using UTF-8 for package control fields and the like
9330 until dpkg has better support, but one thing we can
9331 start doing today is requesting that Debian changelogs
9332 are UTF-8 encoded. At some point in time, we can start
9333 requiring them to do so.
9336 Checking for non-UTF8 characters in a changelog is
9337 trivial. Dump the file through
9338 <example>iconv -f utf-8 -t ucs-4</example>
9339 discard the output, and check the return
9340 value. If there are any characters in the stream
9341 which are invalid UTF-8 sequences, iconv will exit
9342 with an error code; and this will be the case for the
9343 vast majority of other character sets.
9348 <sect2><heading>Defining alternative changelog formats
9352 It is possible to use a different format to the standard
9353 one, by providing a parser for the format you wish to
9358 In order to have <tt>dpkg-parsechangelog</tt> run your
9359 parser, you must include a line within the last 40 lines
9360 of your file matching the Perl regular expression:
9361 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9362 parentheses should be the name of the format. For
9363 example, you might say:
9365 @@@ changelog-format: joebloggs @@@
9367 Changelog format names are non-empty strings of alphanumerics.
9371 If such a line exists then <tt>dpkg-parsechangelog</tt>
9372 will look for the parser as
9373 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9375 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9376 it is an error for it not to find it, or for it not to
9377 be an executable program. The default changelog format
9378 is <tt>dpkg</tt>, and a parser for it is provided with
9379 the <tt>dpkg</tt> package.
9383 The parser will be invoked with the changelog open on
9384 standard input at the start of the file. It should read
9385 the file (it may seek if it wishes) to determine the
9386 information required and return the parsed information
9387 to standard output in the form of a series of control
9388 fields in the standard format. By default it should
9389 return information about only the most recent version in
9390 the changelog; it should accept a
9391 <tt>-v<var>version</var></tt> option to return changes
9392 information from all versions present <em>strictly
9393 after</em> <var>version</var>, and it should then be an
9394 error for <var>version</var> not to be present in the
9400 <list compact="compact">
9401 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9402 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9403 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9404 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9405 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9406 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9407 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9412 If several versions are being returned (due to the use
9413 of <tt>-v</tt>), the urgency value should be of the
9414 highest urgency code listed at the start of any of the
9415 versions requested followed by the concatenated
9416 (space-separated) comments from all the versions
9417 requested; the maintainer, version, distribution and
9418 date should always be from the most recent version.
9422 For the format of the <tt>Changes</tt> field see
9423 <ref id="f-Changes">.
9427 If the changelog format which is being parsed always or
9428 almost always leaves a blank line between individual
9429 change notes these blank lines should be stripped out,
9430 so as to make the resulting output compact.
9434 If the changelog format does not contain date or package
9435 name information this information should be omitted from
9436 the output. The parser should not attempt to synthesise
9437 it or find it from other sources.
9441 If the changelog does not have the expected format the
9442 parser should exit with a nonzero exit status, rather
9443 than trying to muddle through and possibly generating
9448 A changelog parser may not interact with the user at
9454 <sect1 id="pkg-srcsubstvars">
9455 <heading><file>debian/substvars</file> and variable substitutions</heading>
9458 See <ref id="substvars">.
9464 <heading><file>debian/files</file></heading>
9467 See <ref id="debianfiles">.
9471 <sect1><heading><file>debian/tmp</file>
9475 This is the canonical temporary location for the
9476 construction of binary packages by the <tt>binary</tt>
9477 target. The directory <file>tmp</file> serves as the root of
9478 the filesystem tree as it is being constructed (for
9479 example, by using the package's upstream makefiles install
9480 targets and redirecting the output there), and it also
9481 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9482 id="pkg-bincreating">.
9486 If several binary packages are generated from the same
9487 source tree it is usual to use several
9488 <file>debian/tmp<var>something</var></file> directories, for
9489 example <file>tmp-a</file> or <file>tmp-doc</file>.
9493 Whatever <file>tmp</file> directories are created and used by
9494 <tt>binary</tt> must of course be removed by the
9495 <tt>clean</tt> target.</p></sect1>
9499 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9503 As it exists on the FTP site, a Debian source package
9504 consists of three related files. You must have the right
9505 versions of all three to be able to use them.
9510 <tag>Debian source control file - <tt>.dsc</tt></tag>
9512 This file is a control file used by <prgn>dpkg-source</prgn>
9513 to extract a source package.
9514 See <ref id="debiansourcecontrolfiles">.
9518 Original source archive -
9520 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9526 This is a compressed (with <tt>gzip -9</tt>)
9527 <prgn>tar</prgn> file containing the source code from
9528 the upstream authors of the program.
9533 Debianisation diff -
9535 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9541 This is a unified context diff (<tt>diff -u</tt>)
9542 giving the changes which are required to turn the
9543 original source into the Debian source. These changes
9544 may only include editing and creating plain files.
9545 The permissions of files, the targets of symbolic
9546 links and the characteristics of special files or
9547 pipes may not be changed and no files may be removed
9552 All the directories in the diff must exist, except the
9553 <file>debian</file> subdirectory of the top of the source
9554 tree, which will be created by
9555 <prgn>dpkg-source</prgn> if necessary when unpacking.
9559 The <prgn>dpkg-source</prgn> program will
9560 automatically make the <file>debian/rules</file> file
9561 executable (see below).</p></item>
9566 If there is no original source code - for example, if the
9567 package is specially prepared for Debian or the Debian
9568 maintainer is the same as the upstream maintainer - the
9569 format is slightly different: then there is no diff, and the
9571 <file><var>package</var>_<var>version</var>.tar.gz</file>,
9572 and preferably contains a directory named
9573 <file><var>package</var>-<var>version</var></file>.
9578 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9581 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9582 Debian source package. However, if it is not available it
9583 is possible to unpack a Debian source archive as follows:
9584 <enumlist compact="compact">
9587 Untar the tarfile, which will create a <file>.orig</file>
9591 <p>Rename the <file>.orig</file> directory to
9592 <file><var>package</var>-<var>version</var></file>.</p>
9596 Create the subdirectory <file>debian</file> at the top of
9597 the source tree.</p>
9599 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9601 <item><p>Untar the tarfile again if you want a copy of the original
9602 source code alongside the Debianised version.</p>
9607 It is not possible to generate a valid Debian source archive
9608 without using <prgn>dpkg-source</prgn>. In particular,
9609 attempting to use <prgn>diff</prgn> directly to generate the
9610 <file>.diff.gz</file> file will not work.
9614 <heading>Restrictions on objects in source packages</heading>
9617 The source package may not contain any hard links
9619 This is not currently detected when building source
9620 packages, but only when extracting
9624 Hard links may be permitted at some point in the
9625 future, but would require a fair amount of
9627 </footnote>, device special files, sockets or setuid or
9630 Setgid directories are allowed.
9635 The source packaging tools manage the changes between the
9636 original and Debianised source using <prgn>diff</prgn> and
9637 <prgn>patch</prgn>. Turning the original source tree as
9638 included in the <file>.orig.tar.gz</file> into the debianised
9639 source must not involve any changes which cannot be
9640 handled by these tools. Problematic changes which cause
9641 <prgn>dpkg-source</prgn> to halt with an error when
9642 building the source package are:
9643 <list compact="compact">
9644 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9646 <item><p>Changing the targets of symbolic links.</p>
9648 <item><p>Creating directories, other than <file>debian</file>.</p>
9650 <item><p>Changes to the contents of binary files.</p></item>
9651 </list> Changes which cause <prgn>dpkg-source</prgn> to
9652 print a warning but continue anyway are:
9653 <list compact="compact">
9656 Removing files, directories or symlinks.
9658 Renaming a file is not treated specially - it is
9659 seen as the removal of the old file (which
9660 generates a warning, but is otherwise ignored),
9661 and the creation of the new one.
9667 Changed text files which are missing the usual final
9668 newline (either in the original or the modified
9673 Changes which are not represented, but which are not detected by
9674 <prgn>dpkg-source</prgn>, are:
9675 <list compact="compact">
9676 <item><p>Changing the permissions of files (other than
9677 <file>debian/rules</file>) and directories.</p></item>
9682 The <file>debian</file> directory and <file>debian/rules</file>
9683 are handled specially by <prgn>dpkg-source</prgn> - before
9684 applying the changes it will create the <file>debian</file>
9685 directory, and afterwards it will make
9686 <file>debian/rules</file> world-exectuable.
9692 <appendix id="pkg-controlfields">
9693 <heading>Control files and their fields (from old Packaging Manual)</heading>
9696 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9697 data in a common format, known as control files. Binary and
9698 source packages have control data as do the <file>.changes</file>
9699 files which control the installation of uploaded files, and
9700 <prgn>dpkg</prgn>'s internal databases are in a similar
9705 <heading>Syntax of control files</heading>
9708 See <ref id="controlsyntax">.
9712 It is important to note that there are several fields which
9713 are optional as far as <prgn>dpkg</prgn> and the related
9714 tools are concerned, but which must appear in every Debian
9715 package, or whose omission may cause problems.
9720 <heading>List of fields</heading>
9723 See <ref id="controlfieldslist">.
9727 This section now contains only the fields that didn't belong
9728 to the Policy manual.
9731 <sect1 id="pkg-f-Filename">
9732 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9735 These fields in <tt>Packages</tt> files give the
9736 filename(s) of (the parts of) a package in the
9737 distribution directories, relative to the root of the
9738 Debian hierarchy. If the package has been split into
9739 several parts the parts are all listed in order, separated
9744 <sect1 id="pkg-f-Size">
9745 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9748 These fields in <file>Packages</file> files give the size (in
9749 bytes, expressed in decimal) and MD5 checksum of the
9750 file(s) which make(s) up a binary package in the
9751 distribution. If the package is split into several parts
9752 the values for the parts are listed in order, separated by
9757 <sect1 id="pkg-f-Status">
9758 <heading><tt>Status</tt></heading>
9761 This field in <prgn>dpkg</prgn>'s status file records
9762 whether the user wants a package installed, removed or
9763 left alone, whether it is broken (requiring
9764 reinstallation) or not and what its current state on the
9765 system is. Each of these pieces of information is a
9770 <sect1 id="pkg-f-Config-Version">
9771 <heading><tt>Config-Version</tt></heading>
9774 If a package is not installed or not configured, this
9775 field in <prgn>dpkg</prgn>'s status file records the last
9776 version of the package which was successfully
9781 <sect1 id="pkg-f-Conffiles">
9782 <heading><tt>Conffiles</tt></heading>
9785 This field in <prgn>dpkg</prgn>'s status file contains
9786 information about the automatically-managed configuration
9787 files held by a package. This field should <em>not</em>
9788 appear anywhere in a package!
9793 <heading>Obsolete fields</heading>
9796 These are still recognised by <prgn>dpkg</prgn> but should
9797 not appear anywhere any more.
9799 <taglist compact="compact">
9801 <tag><tt>Revision</tt></tag>
9802 <tag><tt>Package-Revision</tt></tag>
9803 <tag><tt>Package_Revision</tt></tag>
9805 The Debian revision part of the package version was
9806 at one point in a separate control file field. This
9807 field went through several names.
9810 <tag><tt>Recommended</tt></tag>
9811 <item>Old name for <tt>Recommends</tt>.</item>
9813 <tag><tt>Optional</tt></tag>
9814 <item>Old name for <tt>Suggests</tt>.</item>
9816 <tag><tt>Class</tt></tag>
9817 <item>Old name for <tt>Priority</tt>.</item>
9826 <appendix id="pkg-conffiles">
9827 <heading>Configuration file handling (from old Packaging Manual)</heading>
9830 <prgn>dpkg</prgn> can do a certain amount of automatic
9831 handling of package configuration files.
9835 Whether this mechanism is appropriate depends on a number of
9836 factors, but basically there are two approaches to any
9837 particular configuration file.
9841 The easy method is to ship a best-effort configuration in the
9842 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9843 handle updates. If the user is unlikely to want to edit the
9844 file, but you need them to be able to without losing their
9845 changes, and a new package with a changed version of the file
9846 is only released infrequently, this is a good approach.
9850 The hard method is to build the configuration file from
9851 scratch in the <prgn>postinst</prgn> script, and to take the
9852 responsibility for fixing any mistakes made in earlier
9853 versions of the package automatically. This will be
9854 appropriate if the file is likely to need to be different on
9858 <sect><heading>Automatic handling of configuration files by
9863 A package may contain a control area file called
9864 <tt>conffiles</tt>. This file should be a list of filenames
9865 of configuration files needing automatic handling, separated
9866 by newlines. The filenames should be absolute pathnames,
9867 and the files referred to should actually exist in the
9872 When a package is upgraded <prgn>dpkg</prgn> will process
9873 the configuration files during the configuration stage,
9874 shortly before it runs the package's <prgn>postinst</prgn>
9879 For each file it checks to see whether the version of the
9880 file included in the package is the same as the one that was
9881 included in the last version of the package (the one that is
9882 being upgraded from); it also compares the version currently
9883 installed on the system with the one shipped with the last
9888 If neither the user nor the package maintainer has changed
9889 the file, it is left alone. If one or the other has changed
9890 their version, then the changed version is preferred - i.e.,
9891 if the user edits their file, but the package maintainer
9892 doesn't ship a different version, the user's changes will
9893 stay, silently, but if the maintainer ships a new version
9894 and the user hasn't edited it the new version will be
9895 installed (with an informative message). If both have
9896 changed their version the user is prompted about the problem
9897 and must resolve the differences themselves.
9901 The comparisons are done by calculating the MD5 message
9902 digests of the files, and storing the MD5 of the file as it
9903 was included in the most recent version of the package.
9907 When a package is installed for the first time
9908 <prgn>dpkg</prgn> will install the file that comes with it,
9909 unless that would mean overwriting a file already on the
9914 However, note that <prgn>dpkg</prgn> will <em>not</em>
9915 replace a conffile that was removed by the user (or by a
9916 script). This is necessary because with some programs a
9917 missing file produces an effect hard or impossible to
9918 achieve in another way, so that a missing file needs to be
9919 kept that way if the user did it.
9923 Note that a package should <em>not</em> modify a
9924 <prgn>dpkg</prgn>-handled conffile in its maintainer
9925 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9926 the user confusing and possibly dangerous options for
9927 conffile update when the package is upgraded.</p>
9930 <sect><heading>Fully-featured maintainer script configuration
9935 For files which contain site-specific information such as
9936 the hostname and networking details and so forth, it is
9937 better to create the file in the package's
9938 <prgn>postinst</prgn> script.
9942 This will typically involve examining the state of the rest
9943 of the system to determine values and other information, and
9944 may involve prompting the user for some information which
9945 can't be obtained some other way.
9949 When using this method there are a couple of important
9950 issues which should be considered:
9954 If you discover a bug in the program which generates the
9955 configuration file, or if the format of the file changes
9956 from one version to the next, you will have to arrange for
9957 the postinst script to do something sensible - usually this
9958 will mean editing the installed configuration file to remove
9959 the problem or change the syntax. You will have to do this
9960 very carefully, since the user may have changed the file,
9961 perhaps to fix the very problem that your script is trying
9962 to deal with - you will have to detect these situations and
9963 deal with them correctly.
9967 If you do go down this route it's probably a good idea to
9968 make the program that generates the configuration file(s) a
9969 separate program in <file>/usr/sbin</file>, by convention called
9970 <file><var>package</var>config</file> and then run that if
9971 appropriate from the post-installation script. The
9972 <tt><var>package</var>config</tt> program should not
9973 unquestioningly overwrite an existing configuration - if its
9974 mode of operation is geared towards setting up a package for
9975 the first time (rather than any arbitrary reconfiguration
9976 later) you should have it check whether the configuration
9977 already exists, and require a <tt>--force</tt> flag to
9978 overwrite it.</p></sect>
9981 <appendix id="pkg-alternatives"><heading>Alternative versions of
9982 an interface - <prgn>update-alternatives</prgn> (from old
9987 When several packages all provide different versions of the
9988 same program or file it is useful to have the system select a
9989 default, but to allow the system administrator to change it
9990 and have their decisions respected.
9994 For example, there are several versions of the <prgn>vi</prgn>
9995 editor, and there is no reason to prevent all of them from
9996 being installed at once, each under their own name
9997 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9998 Nevertheless it is desirable to have the name <tt>vi</tt>
9999 refer to something, at least by default.
10003 If all the packages involved cooperate, this can be done with
10004 <prgn>update-alternatives</prgn>.
10008 Each package provides its own version under its own name, and
10009 calls <prgn>update-alternatives</prgn> in its postinst to
10010 register its version (and again in its prerm to deregister
10015 See the man page <manref name="update-alternatives"
10016 section="8"> for details.
10020 If <prgn>update-alternatives</prgn> does not seem appropriate
10021 you may wish to consider using diversions instead.</p>
10024 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10025 package's version of a file (from old Packaging Manual)
10029 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10030 when it reinstalls the package it belongs to, and to have it
10031 put the file from the package somewhere else instead.
10035 This can be used locally to override a package's version of a
10036 file, or by one package to override another's version (or
10037 provide a wrapper for it).
10041 Before deciding to use a diversion, read <ref
10042 id="pkg-alternatives"> to see if you really want a diversion
10043 rather than several alternative versions of a program.
10047 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10048 and updated by a special program <prgn>dpkg-divert</prgn>.
10049 Please see <manref name="dpkg-divert" section="8"> for full
10050 details of its operation.
10054 When a package wishes to divert a file from another, it should
10055 call <prgn>dpkg-divert</prgn> in its preinst to add the
10056 diversion and rename the existing file. For example,
10057 supposing that a <prgn>smailwrapper</prgn> package wishes to
10058 install a wrapper around <file>/usr/sbin/smail</file>:
10060 if [ install = "$1" ]; then
10061 dpkg-divert --package smailwrapper --add --rename \
10062 --divert /usr/sbin/smail.real /usr/sbin/smail
10064 </example> Testing <tt>$1</tt> is necessary so that the script
10065 doesn't try to add the diversion again when
10066 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10067 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10068 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10069 get installed as the true version.
10073 The postrm has to do the reverse:
10075 if [ remove = "$1" ]; then
10076 dpkg-divert --package smailwrapper --remove --rename \
10077 --divert /usr/sbin/smail.real /usr/sbin/smail
10083 Do not attempt to divert a file which is vitally important for
10084 the system's operation - when using <prgn>dpkg-divert</prgn>
10085 there is a time, after it has been diverted but before
10086 <prgn>dpkg</prgn> has installed the new version, when the file
10087 does not exist.</p>
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