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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 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, 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"
161 id="http://packages.debian.org/debian-policy"></package>
162 (<httpsite>packages.debian.org</httpsite>
163 <httppath>/debian-policy</httppath>).
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name="/doc/debian-policy/"
170 id="http://www.debian.org/doc/debian-policy/"></tt>.
172 <httpsite>www.debian.org</httpsite>
173 <httppath>/doc/debian-policy/</httppath>)
174 Also available from the same directory are several other
175 formats: <file>policy.html.tar.gz</file>
176 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
177 <file>policy.pdf.gz</file>
178 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
179 and <file>policy.ps.gz</file>
180 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
184 The <package>debian-policy</package> package also includes the file
185 <file>upgrading-checklist.txt.gz</file> which indicates policy
186 changes between versions of this document.
191 <heading>Authors and Maintainers</heading>
194 Originally called "Debian GNU/Linux Policy Manual", this
195 manual was initially written in 1996 by Ian Jackson.
196 It was revised on November 27th, 1996 by David A. Morris.
197 Christian Schwarz added new sections on March 15th, 1997,
198 and reworked/restructured it in April-July 1997.
199 Christoph Lameter contributed the "Web Standard".
200 Julian Gilbey largely restructured it in 2001.
204 Since September 1998, the responsibility for the contents of
205 this document lies on the <url name="debian-policy mailing list"
206 id="mailto:debian-policy@lists.debian.org">. Proposals
207 are discussed there and inserted into policy after a certain
208 consensus is established.
209 <!-- insert shameless policy-process plug here eventually -->
210 The actual editing is done by a group of maintainers that have
211 no editorial powers. These are the current maintainers:
214 <item>Julian Gilbey</item>
215 <item>Branden Robinson</item>
216 <item>Josip Rodin</item>
217 <item>Manoj Srivastava</item>
222 While the authors of this document have tried hard to avoid
223 typos and other errors, these do still occur. If you discover
224 an error in this manual or if you want to give any
225 comments, suggestions, or criticisms please send an email to
226 the Debian Policy List,
227 <email>debian-policy@lists.debian.org</email>, or submit a
228 bug report against the <tt>debian-policy</tt> package.
232 Please do not try to reach the individual authors or maintainers
233 of the Policy Manual regarding changes to the Policy.
238 <heading>Related documents</heading>
241 There are several other documents other than this Policy Manual
242 that are necessary to fully understand some Debian policies and
247 The external "sub-policy" documents are referred to in:
248 <list compact="compact">
249 <item><ref id="fhs"></item>
250 <item><ref id="virtual_pkg"></item>
251 <item><ref id="menus"></item>
252 <item><ref id="mime"></item>
253 <item><ref id="perl"></item>
254 <item><ref id="maintscriptprompt"></item>
255 <item><ref id="emacs"></item>
260 In addition to those, which carry the weight of policy, there
261 is the Debian Developer's Reference. This document describes
262 procedures and resources for Debian developers, but it is
263 <em>not</em> normative; rather, it includes things that don't
264 belong in the Policy, such as best practices for developers.
268 The Developer's Reference is available in the
269 <package>developers-reference</package> package.
270 It's also available from the Debian web mirrors at
271 <tt><url name="/doc/developers-reference/"
272 id="http://www.debian.org/doc/developers-reference/"></tt>.
276 <sect id="definitions">
277 <heading>Definitions</heading>
280 The following terms are used in this Policy Manual:
284 The character encoding specified by ANSI X3.4-1986 and its
285 predecessor standards, referred to in MIME as US-ASCII, and
286 corresponding to an encoding in eight bits per character of
287 the first 128 <url id="http://www.unicode.org/"
288 name="Unicode"> characters, with the eighth bit always zero.
292 The transformation format (sometimes called encoding) of
293 <url id="http://www.unicode.org/" name="Unicode"> defined by
294 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
295 name="RFC 3629">. UTF-8 has the useful property of having
296 ASCII as a subset, so any text encoded in ASCII is trivially
306 <heading>The Debian Archive</heading>
309 The Debian GNU/Linux system is maintained and distributed as a
310 collection of <em>packages</em>. Since there are so many of
311 them (currently well over 15000), they are split into
312 <em>sections</em> and given <em>priorities</em> to simplify
313 the handling of them.
317 The effort of the Debian project is to build a free operating
318 system, but not every package we want to make accessible is
319 <em>free</em> in our sense (see the Debian Free Software
320 Guidelines, below), or may be imported/exported without
321 restrictions. Thus, the archive is split into the distribution
322 areas or components<footnote>
323 The Debian archive software uses the term "component" internally
324 and in the Release file format to refer to the division of an
325 archive. The Debian Social Contract refers to distribution
326 areas. This document uses the same terminology as the Social
328 </footnote> based on their licenses and other restrictions.
332 The aims of this are:
334 <list compact="compact">
335 <item>to allow us to make as much software available as we can</item>
336 <item>to allow us to encourage everyone to write free software,
338 <item>to allow us to make it easy for people to produce
339 CD-ROMs of our system without violating any licenses,
340 import/export restrictions, or any other laws.</item>
345 The <em>main</em> distribution area forms the <em>Debian GNU/Linux
350 Packages in the other distribution areas (<tt>contrib</tt>,
351 <tt>non-free</tt>) are not considered to be part of the Debian
352 distribution, although we support their use and provide
353 infrastructure for them (such as our bug-tracking system and
354 mailing lists). This Debian Policy Manual applies to these
359 <heading>The Debian Free Software Guidelines</heading>
361 The Debian Free Software Guidelines (DFSG) form our
362 definition of "free software". These are:
364 <tag>Free Redistribution
367 The license of a Debian component may not restrict any
368 party from selling or giving away the software as a
369 component of an aggregate software distribution
370 containing programs from several different
371 sources. The license may not require a royalty or
372 other fee for such sale.
377 The program must include source code, and must allow
378 distribution in source code as well as compiled form.
383 The license must allow modifications and derived
384 works, and must allow them to be distributed under the
385 same terms as the license of the original software.
387 <tag>Integrity of The Author's Source Code
390 The license may restrict source-code from being
391 distributed in modified form <em>only</em> if the
392 license allows the distribution of "patch files"
393 with the source code for the purpose of modifying the
394 program at build time. The license must explicitly
395 permit distribution of software built from modified
396 source code. The license may require derived works to
397 carry a different name or version number from the
398 original software. (This is a compromise. The Debian
399 Project encourages all authors to not restrict any
400 files, source or binary, from being modified.)
402 <tag>No Discrimination Against Persons or Groups
405 The license must not discriminate against any person
408 <tag>No Discrimination Against Fields of Endeavor
411 The license must not restrict anyone from making use
412 of the program in a specific field of endeavor. For
413 example, it may not restrict the program from being
414 used in a business, or from being used for genetic
417 <tag>Distribution of License
420 The rights attached to the program must apply to all
421 to whom the program is redistributed without the need
422 for execution of an additional license by those
425 <tag>License Must Not Be Specific to Debian
428 The rights attached to the program must not depend on
429 the program's being part of a Debian system. If the
430 program is extracted from Debian and used or
431 distributed without Debian but otherwise within the
432 terms of the program's license, all parties to whom
433 the program is redistributed must have the same
434 rights as those that are granted in conjunction with
437 <tag>License Must Not Contaminate Other Software
440 The license must not place restrictions on other
441 software that is distributed along with the licensed
442 software. For example, the license must not insist
443 that all other programs distributed on the same medium
444 must be free software.
446 <tag>Example Licenses
449 The "GPL," "BSD," and "Artistic" licenses are examples of
450 licenses that we consider <em>free</em>.
457 <heading>Distribution areas</heading>
460 <heading>The main distribution area</heading>
463 Every package in <em>main</em> must comply with the DFSG
464 (Debian Free Software Guidelines).
468 In addition, the packages in <em>main</em>
469 <list compact="compact">
471 must not require a package outside of <em>main</em>
472 for compilation or execution (thus, the package must
473 not declare a "Depends", "Recommends", or
474 "Build-Depends" relationship on a non-<em>main</em>
478 must not be so buggy that we refuse to support them,
482 must meet all policy requirements presented in this
491 <heading>The contrib distribution area</heading>
494 Every package in <em>contrib</em> must comply with the DFSG.
498 In addition, the packages in <em>contrib</em>
499 <list compact="compact">
501 must not be so buggy that we refuse to support them,
505 must meet all policy requirements presented in this
513 Examples of packages which would be included in
514 <em>contrib</em> are:
515 <list compact="compact">
517 free packages which require <em>contrib</em>,
518 <em>non-free</em> packages or packages which are not
519 in our archive at all for compilation or execution,
523 wrapper packages or other sorts of free accessories for
530 <sect1 id="non-free">
531 <heading>The non-free distribution area</heading>
534 Packages must be placed in <em>non-free</em> if they are
535 not compliant with the DFSG or are encumbered by patents
536 or other legal issues that make their distribution
541 In addition, the packages in <em>non-free</em>
542 <list compact="compact">
544 must not be so buggy that we refuse to support them,
548 must meet all policy requirements presented in this
549 manual that it is possible for them to meet.
551 It is possible that there are policy
552 requirements which the package is unable to
553 meet, for example, if the source is
554 unavailable. These situations will need to be
555 handled on a case-by-case basis.
564 <sect id="pkgcopyright">
565 <heading>Copyright considerations</heading>
568 Every package must be accompanied by a verbatim copy of
569 its copyright and distribution license in the file
570 <file>/usr/share/doc/<var>package</var>/copyright</file>
571 (see <ref id="copyrightfile"> for further details).
575 We reserve the right to restrict files from being included
576 anywhere in our archives if
577 <list compact="compact">
579 their use or distribution would break a law,
582 there is an ethical conflict in their distribution or
586 we would have to sign a license for them, or
589 their distribution would conflict with other project
596 Programs whose authors encourage the user to make
597 donations are fine for the main distribution, provided
598 that the authors do not claim that not donating is
599 immoral, unethical, illegal or something similar; in such
600 a case they must go in <em>non-free</em>.
604 Packages whose copyright permission notices (or patent
605 problems) do not even allow redistribution of binaries
606 only, and where no special permission has been obtained,
607 must not be placed on the Debian FTP site and its mirrors
612 Note that under international copyright law (this applies
613 in the United States, too), <em>no</em> distribution or
614 modification of a work is allowed without an explicit
615 notice saying so. Therefore a program without a copyright
616 notice <em>is</em> copyrighted and you may not do anything
617 to it without risking being sued! Likewise if a program
618 has a copyright notice but no statement saying what is
619 permitted then nothing is permitted.
623 Many authors are unaware of the problems that restrictive
624 copyrights (or lack of copyright notices) can cause for
625 the users of their supposedly-free software. It is often
626 worthwhile contacting such authors diplomatically to ask
627 them to modify their license terms. However, this can be a
628 politically difficult thing to do and you should ask for
629 advice on the <tt>debian-legal</tt> mailing list first, as
634 When in doubt about a copyright, send mail to
635 <email>debian-legal@lists.debian.org</email>. Be prepared
636 to provide us with the copyright statement. Software
637 covered by the GPL, public domain software and BSD-like
638 copyrights are safe; be wary of the phrases "commercial
639 use prohibited" and "distribution restricted".
643 <sect id="subsections">
644 <heading>Sections</heading>
647 The packages in the distribution areas <em>main</em>,
648 <em>contrib</em> and <em>non-free</em> are grouped further
649 into <em>sections</em> to simplify handling.
653 The distribution area and section for each package should be
654 specified in the package's <tt>Section</tt> control record
655 (see <ref id="f-Section">). However, the maintainer of the
656 Debian archive may override this selection to ensure the
657 consistency of the Debian distribution. The
658 <tt>Section</tt> field should be of the form:
659 <list compact="compact">
661 <em>section</em> if the package is in the
662 <em>main</em> distribution area,
665 <em>area/section</em> if the package is in
666 the <em>contrib</em> or <em>non-free</em>
673 The Debian archive maintainers provide the authoritative
674 list of sections. At present, they are:
675 <em>admin</em>, <em>comm</em>,
676 <em>devel</em>, <em>doc</em>,
677 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
678 <em>games</em>, <em>gnome</em>, <em>graphics</em>,
679 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
680 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
681 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
683 <em>otherosfs</em>, <em>perl</em>, <em>python</em>,
684 <em>science</em>, <em>shells</em>,
685 <em>sound</em>, <em>tex</em>, <em>text</em>,
686 <em>utils</em>, <em>web</em>, <em>x11</em>.
690 <sect id="priorities">
691 <heading>Priorities</heading>
694 Each package should have a <em>priority</em> value, which is
695 included in the package's <em>control record</em>
696 (see <ref id="f-Priority">).
697 This information is used by the Debian package management tools to
698 separate high-priority packages from less-important packages.
702 The following <em>priority levels</em> are recognized by the
703 Debian package management tools.
705 <tag><tt>required</tt></tag>
707 Packages which are necessary for the proper
708 functioning of the system (usually, this means that
709 dpkg functionality depends on these packages).
710 Removing a <tt>required</tt> package may cause your
711 system to become totally broken and you may not even
712 be able to use <prgn>dpkg</prgn> to put things back,
713 so only do so if you know what you are doing. Systems
714 with only the <tt>required</tt> packages are probably
715 unusable, but they do have enough functionality to
716 allow the sysadmin to boot and install more software.
718 <tag><tt>important</tt></tag>
720 Important programs, including those which one would
721 expect to find on any Unix-like system. If the
722 expectation is that an experienced Unix person who
723 found it missing would say "What on earth is going on,
724 where is <prgn>foo</prgn>?", it must be an
725 <tt>important</tt> package.<footnote>
726 This is an important criterion because we are
727 trying to produce, amongst other things, a free
730 Other packages without which the system will not run
731 well or be usable must also have priority
732 <tt>important</tt>. This does
733 <em>not</em> include Emacs, the X Window System, TeX
734 or any other large applications. The
735 <tt>important</tt> packages are just a bare minimum of
736 commonly-expected and necessary tools.
738 <tag><tt>standard</tt></tag>
740 These packages provide a reasonably small but not too
741 limited character-mode system. This is what will be
742 installed by default if the user doesn't select anything
743 else. It doesn't include many large applications.
745 <tag><tt>optional</tt></tag>
747 (In a sense everything that isn't required is
748 optional, but that's not what is meant here.) This is
749 all the software that you might reasonably want to
750 install if you didn't know what it was and don't have
751 specialized requirements. This is a much larger system
752 and includes the X Window System, a full TeX
753 distribution, and many applications. Note that
754 optional packages should not conflict with each other.
756 <tag><tt>extra</tt></tag>
758 This contains all packages that conflict with others
759 with required, important, standard or optional
760 priorities, or are only likely to be useful if you
761 already know what they are or have specialized
762 requirements (such as packages containing only detached
769 Packages must not depend on packages with lower priority
770 values (excluding build-time dependencies). In order to
771 ensure this, the priorities of one or more packages may need
780 <heading>Binary packages</heading>
783 The Debian GNU/Linux distribution is based on the Debian
784 package management system, called <prgn>dpkg</prgn>. Thus,
785 all packages in the Debian distribution must be provided
786 in the <tt>.deb</tt> file format.
790 <heading>The package name</heading>
793 Every package must have a name that's unique within the Debian
798 The package name is included in the control field
799 <tt>Package</tt>, the format of which is described
800 in <ref id="f-Package">.
801 The package name is also included as a part of the file name
802 of the <tt>.deb</tt> file.
807 <heading>The version of a package</heading>
810 Every package has a version number recorded in its
811 <tt>Version</tt> control file field, described in
812 <ref id="f-Version">.
816 The package management system imposes an ordering on version
817 numbers, so that it can tell whether packages are being up- or
818 downgraded and so that package system front end applications
819 can tell whether a package it finds available is newer than
820 the one installed on the system. The version number format
821 has the most significant parts (as far as comparison is
822 concerned) at the beginning.
826 If an upstream package has problematic version numbers they
827 should be converted to a sane form for use in the
828 <tt>Version</tt> field.
832 <heading>Version numbers based on dates</heading>
835 In general, Debian packages should use the same version
836 numbers as the upstream sources.
840 However, in some cases where the upstream version number is
841 based on a date (e.g., a development "snapshot" release) the
842 package management system cannot handle these version
843 numbers without epochs. For example, dpkg will consider
844 "96May01" to be greater than "96Dec24".
848 To prevent having to use epochs for every new upstream
849 version, the date based portion of the version number
850 should be changed to the following format in such cases:
851 "19960501", "19961224". It is up to the maintainer whether
852 they want to bother the upstream maintainer to change
853 the version numbers upstream, too.
857 Note that other version formats based on dates which are
858 parsed correctly by the package management system should
859 <em>not</em> be changed.
863 Native Debian packages (i.e., packages which have been
864 written especially for Debian) whose version numbers include
865 dates should always use the "YYYYMMDD" format.
872 <heading>The maintainer of a package</heading>
875 Every package must have a Debian maintainer (the
876 maintainer may be one person or a group of people
877 reachable from a common email address, such as a mailing
878 list). The maintainer is responsible for ensuring that
879 the package is placed in the appropriate distributions.
883 The maintainer must be specified in the
884 <tt>Maintainer</tt> control field with their correct name
885 and a working email address. If one person maintains
886 several packages, they should try to avoid having
887 different forms of their name and email address in
888 the <tt>Maintainer</tt> fields of those packages.
892 The format of the <tt>Maintainer</tt> control field is
893 described in <ref id="f-Maintainer">.
897 If the maintainer of a package quits from the Debian
898 project, "Debian QA Group"
899 <email>packages@qa.debian.org</email> takes over the
900 maintainer-ship of the package until someone else
901 volunteers for that task. These packages are called
902 <em>orphaned packages</em>.<footnote>
903 The detailed procedure for doing this gracefully can
904 be found in the Debian Developer's Reference,
905 see <ref id="related">.
910 <sect id="descriptions">
911 <heading>The description of a package</heading>
914 Every Debian package must have an extended description
915 stored in the appropriate field of the control record.
916 The technical information about the format of the
917 <tt>Description</tt> field is in <ref id="f-Description">.
921 The description should describe the package (the program) to a
922 user (system administrator) who has never met it before so that
923 they have enough information to decide whether they want to
924 install it. This description should not just be copied verbatim
925 from the program's documentation.
929 Put important information first, both in the synopsis and
930 extended description. Sometimes only the first part of the
931 synopsis or of the description will be displayed. You can
932 assume that there will usually be a way to see the whole
933 extended description.
937 The description should also give information about the
938 significant dependencies and conflicts between this package
939 and others, so that the user knows why these dependencies and
940 conflicts have been declared.
944 Instructions for configuring or using the package should
945 not be included (that is what installation scripts,
946 manual pages, info files, etc., are for). Copyright
947 statements and other administrivia should not be included
948 either (that is what the copyright file is for).
951 <sect1 id="synopsis"><heading>The single line synopsis</heading>
954 The single line synopsis should be kept brief - certainly
959 Do not include the package name in the synopsis line. The
960 display software knows how to display this already, and you
961 do not need to state it. Remember that in many situations
962 the user may only see the synopsis line - make it as
963 informative as you can.
968 <sect1 id="extendeddesc"><heading>The extended description</heading>
971 Do not try to continue the single line synopsis into the
972 extended description. This will not work correctly when
973 the full description is displayed, and makes no sense
974 where only the summary (the single line synopsis) is
979 The extended description should describe what the package
980 does and how it relates to the rest of the system (in terms
981 of, for example, which subsystem it is which part of).
985 The description field needs to make sense to anyone, even
986 people who have no idea about any of the things the
987 package deals with.<footnote>
988 The blurb that comes with a program in its
989 announcements and/or <prgn>README</prgn> files is
990 rarely suitable for use in a description. It is
991 usually aimed at people who are already in the
992 community where the package is used.
1001 <heading>Dependencies</heading>
1004 Every package must specify the dependency information
1005 about other packages that are required for the first to
1010 For example, a dependency entry must be provided for any
1011 shared libraries required by a dynamically-linked executable
1012 binary in a package.
1016 Packages are not required to declare any dependencies they
1017 have on other packages which are marked <tt>Essential</tt>
1018 (see below), and should not do so unless they depend on a
1019 particular version of that package.<footnote>
1021 Essential is defined as the minimal set of functionality
1022 that must be available and usable on the system even
1023 when packages are in an unconfigured (but unpacked)
1024 state. This is needed to avoid unresolvable dependency
1025 loops on upgrade. If packages add unnecessary
1026 dependencies on packages in this set, the chances that
1027 there <strong>will</strong> be an unresolvable
1028 dependency loop caused by forcing these Essential
1029 packages to be configured first before they need to be
1030 is greatly increased. It also increases the chances
1031 that frontends will be unable to
1032 <strong>calculate</strong> an upgrade path, even if one
1036 Also, it's pretty unlikely that functionality from
1037 Essential shall ever be removed (which is one reason why
1038 care must be taken before adding to the Essential
1039 packages set), but <em>packages</em> have been removed
1040 from the Essential set when the functionality moved to a
1041 different package. So depending on these packages
1042 <em>just in case</em> they stop being essential does way
1043 more harm than good.
1049 Sometimes, a package requires another package to be installed
1050 <em>and</em> configured before it can be installed. In this
1051 case, you must specify a <tt>Pre-Depends</tt> entry for
1056 You should not specify a <tt>Pre-Depends</tt> entry for a
1057 package before this has been discussed on the
1058 <tt>debian-devel</tt> mailing list and a consensus about
1059 doing that has been reached.
1063 The format of the package interrelationship control fields is
1064 described in <ref id="relationships">.
1068 <sect id="virtual_pkg">
1069 <heading>Virtual packages</heading>
1072 Sometimes, there are several packages which offer
1073 more-or-less the same functionality. In this case, it's
1074 useful to define a <em>virtual package</em> whose name
1075 describes that common functionality. (The virtual
1076 packages only exist logically, not physically; that's why
1077 they are called <em>virtual</em>.) The packages with this
1078 particular function will then <em>provide</em> the virtual
1079 package. Thus, any other package requiring that function
1080 can simply depend on the virtual package without having to
1081 specify all possible packages individually.
1085 All packages should use virtual package names where
1086 appropriate, and arrange to create new ones if necessary.
1087 They should not use virtual package names (except privately,
1088 amongst a cooperating group of packages) unless they have
1089 been agreed upon and appear in the list of virtual package
1090 names. (See also <ref id="virtual">)
1094 The latest version of the authoritative list of virtual
1095 package names can be found in the <tt>debian-policy</tt> package.
1096 It is also available from the Debian web mirrors at
1097 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1098 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1102 The procedure for updating the list is described in the preface
1109 <heading>Base system</heading>
1112 The <tt>base system</tt> is a minimum subset of the Debian
1113 GNU/Linux system that is installed before everything else
1114 on a new system. Only very few packages are allowed to form
1115 part of the base system, in order to keep the required disk
1120 The base system consists of all those packages with priority
1121 <tt>required</tt> or <tt>important</tt>. Many of them will
1122 be tagged <tt>essential</tt> (see below).
1127 <heading>Essential packages</heading>
1130 Some packages are tagged <tt>essential</tt> for a system
1131 using the <tt>Essential</tt> control file field.
1132 The format of the <tt>Essential</tt> control field is
1133 described in <ref id="f-Essential">.
1137 Since these packages cannot be easily removed (one has to
1138 specify an extra <em>force option</em> to
1139 <prgn>dpkg</prgn> to do so), this flag must not be used
1140 unless absolutely necessary. A shared library package
1141 must not be tagged <tt>essential</tt>; dependencies will
1142 prevent its premature removal, and we need to be able to
1143 remove it when it has been superseded.
1147 Since dpkg will not prevent upgrading of other packages
1148 while an <tt>essential</tt> package is in an unconfigured
1149 state, all <tt>essential</tt> packages must supply all of
1150 their core functionality even when unconfigured. If the
1151 package cannot satisfy this requirement it must not be
1152 tagged as essential, and any packages depending on this
1153 package must instead have explicit dependency fields as
1158 You must not tag any packages <tt>essential</tt> before
1159 this has been discussed on the <tt>debian-devel</tt>
1160 mailing list and a consensus about doing that has been
1165 <sect id="maintscripts">
1166 <heading>Maintainer Scripts</heading>
1169 The package installation scripts should avoid producing
1170 output which is unnecessary for the user to see and
1171 should rely on <prgn>dpkg</prgn> to stave off boredom on
1172 the part of a user installing many packages. This means,
1173 amongst other things, using the <tt>--quiet</tt> option on
1174 <prgn>install-info</prgn>.
1178 Errors which occur during the execution of an installation
1179 script must be checked and the installation must not
1180 continue after an error.
1184 Note that in general <ref id="scripts"> applies to package
1185 maintainer scripts, too.
1189 You should not use <prgn>dpkg-divert</prgn> on a file
1190 belonging to another package without consulting the
1191 maintainer of that package first.
1195 All packages which supply an instance of a common command
1196 name (or, in general, filename) should generally use
1197 <prgn>update-alternatives</prgn>, so that they may be
1198 installed together. If <prgn>update-alternatives</prgn>
1199 is not used, then each package must use
1200 <tt>Conflicts</tt> to ensure that other packages are
1201 de-installed. (In this case, it may be appropriate to
1202 specify a conflict against earlier versions of something
1203 that previously did not use
1204 <prgn>update-alternatives</prgn>; this is an exception to
1205 the usual rule that versioned conflicts should be
1209 <sect1 id="maintscriptprompt">
1210 <heading>Prompting in maintainer scripts</heading>
1212 Package maintainer scripts may prompt the user if
1213 necessary. Prompting should be done by communicating
1214 through a program, such as <prgn>debconf</prgn>, which
1215 conforms to the Debian Configuration Management
1216 Specification, version 2 or higher. Prompting the user by
1217 other means, such as by hand<footnote>
1218 From the Jargon file: by hand 2. By extension,
1219 writing code which does something in an explicit or
1220 low-level way for which a presupplied library
1221 (<em>debconf, in this instance</em>) routine ought
1222 to have been available.
1223 </footnote>, is now deprecated.
1227 The Debian Configuration Management Specification is included
1228 in the <file>debconf_specification</file> files in the
1229 <package>debian-policy</package> package.
1230 It is also available from the Debian web mirrors at
1231 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1232 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1236 Packages which use the Debian Configuration Management
1237 Specification may contain an additional
1238 <prgn>config</prgn> script and a <tt>templates</tt>
1239 file in their control archive<footnote>
1240 The control.tar.gz inside the .deb.
1241 See <manref name="deb" section="5">.
1243 The <prgn>config</prgn> script might be run before the
1244 <prgn>preinst</prgn> script, and before the package is unpacked
1245 or any of its dependencies or pre-dependencies are satisfied.
1246 Therefore it must work using only the tools present in
1247 <em>essential</em> packages.<footnote>
1248 <package>Debconf</package> or another tool that
1249 implements the Debian Configuration Management
1250 Specification will also be installed, and any
1251 versioned dependencies on it will be satisfied
1252 before preconfiguration begins.
1257 Packages which use the Debian Configuration Management
1258 Specification must allow for translation of their user-visible
1259 messages by using a gettext-based system such as the one
1260 provided by the <package>po-debconf</package> package.
1264 Packages should try to minimize the amount of prompting
1265 they need to do, and they should ensure that the user
1266 will only ever be asked each question once. This means
1267 that packages should try to use appropriate shared
1268 configuration files (such as <file>/etc/papersize</file> and
1269 <file>/etc/news/server</file>), and shared
1270 <package>debconf</package> variables rather than each
1271 prompting for their own list of required pieces of
1276 It also means that an upgrade should not ask the same
1277 questions again, unless the user has used
1278 <tt>dpkg --purge</tt> to remove the package's configuration.
1279 The answers to configuration questions should be stored in an
1280 appropriate place in <file>/etc</file> so that the user can
1281 modify them, and how this has been done should be
1286 If a package has a vitally important piece of
1287 information to pass to the user (such as "don't run me
1288 as I am, you must edit the following configuration files
1289 first or you risk your system emitting badly-formatted
1290 messages"), it should display this in the
1291 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1292 prompt the user to hit return to acknowledge the
1293 message. Copyright messages do not count as vitally
1294 important (they belong in
1295 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1296 neither do instructions on how to use a program (these
1297 should be in on-line documentation, where all the users
1302 Any necessary prompting should almost always be confined
1303 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1304 script. If it is done in the <prgn>postinst</prgn>, it
1305 should be protected with a conditional so that
1306 unnecessary prompting doesn't happen if a package's
1307 installation fails and the <prgn>postinst</prgn> is
1308 called with <tt>abort-upgrade</tt>,
1309 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1319 <heading>Source packages</heading>
1321 <sect id="standardsversion">
1322 <heading>Standards conformance</heading>
1325 Source packages should specify the most recent version number
1326 of this policy document with which your package complied
1327 when it was last updated.
1331 This information may be used to file bug reports
1332 automatically if your package becomes too much out of date.
1336 The version is specified in the <tt>Standards-Version</tt>
1338 The format of the <tt>Standards-Version</tt> field is
1339 described in <ref id="f-Standards-Version">.
1343 You should regularly, and especially if your package has
1344 become out of date, check for the newest Policy Manual
1345 available and update your package, if necessary. When your
1346 package complies with the new standards you should update the
1347 <tt>Standards-Version</tt> source package field and
1348 release it.<footnote>
1349 See the file <file>upgrading-checklist</file> for
1350 information about policy which has changed between
1351 different versions of this document.
1357 <sect id="pkg-relations">
1358 <heading>Package relationships</heading>
1361 Source packages should specify which binary packages they
1362 require to be installed or not to be installed in order to
1363 build correctly. For example, if building a package
1364 requires a certain compiler, then the compiler should be
1365 specified as a build-time dependency.
1369 It is not necessary to explicitly specify build-time
1370 relationships on a minimal set of packages that are always
1371 needed to compile, link and put in a Debian package a
1372 standard "Hello World!" program written in C or C++. The
1373 required packages are called <em>build-essential</em>, and
1374 an informational list can be found in
1375 <file>/usr/share/doc/build-essential/list</file> (which is
1376 contained in the <tt>build-essential</tt>
1379 <list compact="compact">
1381 This allows maintaining the list separately
1382 from the policy documents (the list does not
1383 need the kind of control that the policy
1387 Having a separate package allows one to install
1388 the build-essential packages on a machine, as
1389 well as allowing other packages such as tasks to
1390 require installation of the build-essential
1391 packages using the depends relation.
1394 The separate package allows bug reports against
1395 the list to be categorized separately from
1396 the policy management process in the BTS.
1403 When specifying the set of build-time dependencies, one
1404 should list only those packages explicitly required by the
1405 build. It is not necessary to list packages which are
1406 required merely because some other package in the list of
1407 build-time dependencies depends on them.<footnote>
1408 The reason for this is that dependencies change, and
1409 you should list all those packages, and <em>only</em>
1410 those packages that <em>you</em> need directly. What
1411 others need is their business. For example, if you
1412 only link against <file>libimlib</file>, you will need to
1413 build-depend on <package>libimlib2-dev</package> but
1414 not against any <tt>libjpeg*</tt> packages, even
1415 though <tt>libimlib2-dev</tt> currently depends on
1416 them: installation of <package>libimlib2-dev</package>
1417 will automatically ensure that all of its run-time
1418 dependencies are satisfied.
1423 If build-time dependencies are specified, it must be
1424 possible to build the package and produce working binaries
1425 on a system with only essential and build-essential
1426 packages installed and also those required to satisfy the
1427 build-time relationships (including any implied
1428 relationships). In particular, this means that version
1429 clauses should be used rigorously in build-time
1430 relationships so that one cannot produce bad or
1431 inconsistently configured packages when the relationships
1432 are properly satisfied.
1436 <ref id="relationships"> explains the technical details.
1441 <heading>Changes to the upstream sources</heading>
1444 If changes to the source code are made that are not
1445 specific to the needs of the Debian system, they should be
1446 sent to the upstream authors in whatever form they prefer
1447 so as to be included in the upstream version of the
1452 If you need to configure the package differently for
1453 Debian or for Linux, and the upstream source doesn't
1454 provide a way to do so, you should add such configuration
1455 facilities (for example, a new <prgn>autoconf</prgn> test
1456 or <tt>#define</tt>) and send the patch to the upstream
1457 authors, with the default set to the way they originally
1458 had it. You can then easily override the default in your
1459 <file>debian/rules</file> or wherever is appropriate.
1463 You should make sure that the <prgn>configure</prgn> utility
1464 detects the correct architecture specification string
1465 (refer to <ref id="arch-spec"> for details).
1469 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1470 <prgn>configure</prgn> scripts are used, you should edit the
1471 <file>.in</file> files rather than editing the
1472 <prgn>Makefile</prgn> directly. This allows the user to
1473 reconfigure the package if necessary. You should
1474 <em>not</em> configure the package and edit the generated
1475 <prgn>Makefile</prgn>! This makes it impossible for someone
1476 else to later reconfigure the package without losing the
1482 <sect id="dpkgchangelog">
1483 <heading>Debian changelog: <file>debian/changelog</file></heading>
1486 Changes in the Debian version of the package should be
1487 briefly explained in the Debian changelog file
1488 <file>debian/changelog</file>.<footnote>
1490 Mistakes in changelogs are usually best rectified by
1491 making a new changelog entry rather than "rewriting
1492 history" by editing old changelog entries.
1495 This includes modifications
1496 made in the Debian package compared to the upstream one
1497 as well as other changes and updates to the package.
1499 Although there is nothing stopping an author who is also
1500 the Debian maintainer from using this changelog for all
1501 their changes, it will have to be renamed if the Debian
1502 and upstream maintainers become different people. In such
1503 a case, however, it might be better to maintain the package
1504 as a non-native package.
1509 The format of the <file>debian/changelog</file> allows the
1510 package building tools to discover which version of the package
1511 is being built and find out other release-specific information.
1515 That format is a series of entries like this:
1517 <example compact="compact">
1518 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1520 [optional blank line(s), stripped]
1522 * <var>change details</var>
1523 <var>more change details</var>
1525 [blank line(s), included in output of dpkg-parsechangelog]
1527 * <var>even more change details</var>
1529 [optional blank line(s), stripped]
1531 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1536 <var>package</var> and <var>version</var> are the source
1537 package name and version number.
1541 <var>distribution(s)</var> lists the distributions where
1542 this version should be installed when it is uploaded - it
1543 is copied to the <tt>Distribution</tt> field in the
1544 <file>.changes</file> file. See <ref id="f-Distribution">.
1548 <var>urgency</var> is the value for the <tt>Urgency</tt>
1549 field in the <file>.changes</file> file for the upload
1550 (see <ref id="f-Urgency">). It is not possible to specify
1551 an urgency containing commas; commas are used to separate
1552 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1553 <prgn>dpkg</prgn> changelog format (though there is
1554 currently only one useful <var>keyword</var>,
1559 The change details may in fact be any series of lines
1560 starting with at least two spaces, but conventionally each
1561 change starts with an asterisk and a separating space and
1562 continuation lines are indented so as to bring them in
1563 line with the start of the text above. Blank lines may be
1564 used here to separate groups of changes, if desired.
1568 If this upload resolves bugs recorded in the Bug Tracking
1569 System (BTS), they may be automatically closed on the
1570 inclusion of this package into the Debian archive by
1571 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1572 in the change details.<footnote>
1573 To be precise, the string should match the following
1574 Perl regular expression:
1576 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1578 Then all of the bug numbers listed will be closed by the
1579 archive maintenance script (<prgn>katie</prgn>) using the
1580 <var>version</var> of the changelog entry.
1582 This information is conveyed via the <tt>Closes</tt> field
1583 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1587 The maintainer name and email address used in the changelog
1588 should be the details of the person uploading <em>this</em>
1589 version. They are <em>not</em> necessarily those of the
1590 usual package maintainer. The information here will be
1591 copied to the <tt>Changed-By</tt> field in the
1592 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1593 and then later used to send an acknowledgement when the
1594 upload has been installed.
1598 The <var>date</var> must be in RFC822 format<footnote>
1599 This is generated by <tt>date -R</tt>.
1600 </footnote>; it must include the time zone specified
1601 numerically, with the time zone name or abbreviation
1602 optionally present as a comment in parentheses.
1606 The first "title" line with the package name must start
1607 at the left hand margin. The "trailer" line with the
1608 maintainer and date details must be preceded by exactly
1609 one space. The maintainer details and the date must be
1610 separated by exactly two spaces.
1614 The entire changelog must be encoded in UTF-8.
1618 For more information on placement of the changelog files
1619 within binary packages, please see <ref id="changelogs">.
1623 <sect id="dpkgcopyright">
1624 <heading>Copyright: <file>debian/copyright</file></heading>
1626 Every package must be accompanied by a verbatim copy of
1627 its copyright and distribution license in the file
1628 <file>/usr/share/doc/<var>package</var>/copyright</file>
1629 (see <ref id="copyrightfile"> for further details). Also see
1630 <ref id="pkgcopyright"> for further considerations relayed
1631 to copyrights for packages.
1635 <heading>Error trapping in makefiles</heading>
1638 When <prgn>make</prgn> invokes a command in a makefile
1639 (including your package's upstream makefiles and
1640 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1641 means that <prgn>sh</prgn>'s usual bad error handling
1642 properties apply: if you include a miniature script as one
1643 of the commands in your makefile you'll find that if you
1644 don't do anything about it then errors are not detected
1645 and <prgn>make</prgn> will blithely continue after
1650 Every time you put more than one shell command (this
1651 includes using a loop) in a makefile command you
1652 must make sure that errors are trapped. For
1653 simple compound commands, such as changing directory and
1654 then running a program, using <tt>&&</tt> rather
1655 than semicolon as a command separator is sufficient. For
1656 more complex commands including most loops and
1657 conditionals you should include a separate <tt>set -e</tt>
1658 command at the start of every makefile command that's
1659 actually one of these miniature shell scripts.
1663 <sect id="timestamps">
1664 <heading>Time Stamps</heading>
1666 Maintainers should preserve the modification times of the
1667 upstream source files in a package, as far as is reasonably
1669 The rationale is that there is some information conveyed
1670 by knowing the age of the file, for example, you could
1671 recognize that some documentation is very old by looking
1672 at the modification time, so it would be nice if the
1673 modification time of the upstream source would be
1679 <sect id="restrictions">
1680 <heading>Restrictions on objects in source packages</heading>
1683 The source package may not contain any hard links<footnote>
1685 This is not currently detected when building source
1686 packages, but only when extracting
1690 Hard links may be permitted at some point in the
1691 future, but would require a fair amount of
1694 </footnote>, device special files, sockets or setuid or
1695 setgid files.<footnote>
1696 Setgid directories are allowed.
1701 <sect id="debianrules">
1702 <heading>Main building script: <file>debian/rules</file></heading>
1705 This file must be an executable makefile, and contains the
1706 package-specific recipes for compiling the package and
1707 building binary package(s) from the source.
1711 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1712 so that it can be invoked by saying its name rather than
1713 invoking <prgn>make</prgn> explicitly.
1717 Since an interactive <file>debian/rules</file> script makes it
1718 impossible to auto-compile that package and also makes it
1719 hard for other people to reproduce the same binary
1720 package, all <em>required targets</em> MUST be
1721 non-interactive. At a minimum, required targets are the
1722 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1723 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1724 <em>binary-indep</em>, and <em>build</em>. It also follows
1725 that any target that these targets depend on must also be
1730 The targets are as follows (required unless stated otherwise):
1732 <tag><tt>build</tt></tag>
1735 The <tt>build</tt> target should perform all the
1736 configuration and compilation of the package.
1737 If a package has an interactive pre-build
1738 configuration routine, the Debianized source package
1739 must either be built after this has taken place (so
1740 that the binary package can be built without rerunning
1741 the configuration) or the configuration routine
1742 modified to become non-interactive. (The latter is
1743 preferable if there are architecture-specific features
1744 detected by the configuration routine.)
1748 For some packages, notably ones where the same
1749 source tree is compiled in different ways to produce
1750 two binary packages, the <tt>build</tt> target
1751 does not make much sense. For these packages it is
1752 good enough to provide two (or more) targets
1753 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1754 for each of the ways of building the package, and a
1755 <tt>build</tt> target that does nothing. The
1756 <tt>binary</tt> target will have to build the
1757 package in each of the possible ways and make the
1758 binary package out of each.
1762 The <tt>build</tt> target must not do anything
1763 that might require root privilege.
1767 The <tt>build</tt> target may need to run the
1768 <tt>clean</tt> target first - see below.
1772 When a package has a configuration and build routine
1773 which takes a long time, or when the makefiles are
1774 poorly designed, or when <tt>build</tt> needs to
1775 run <tt>clean</tt> first, it is a good idea to
1776 <tt>touch build</tt> when the build process is
1777 complete. This will ensure that if <tt>debian/rules
1778 build</tt> is run again it will not rebuild the whole
1780 Another common way to do this is for <tt>build</tt>
1781 to depend on <prgn>build-stamp</prgn> and to do
1782 nothing else, and for the <prgn>build-stamp</prgn>
1783 target to do the building and to <tt>touch
1784 build-stamp</tt> on completion. This is
1785 especially useful if the build routine creates a
1786 file or directory called <tt>build</tt>; in such a
1787 case, <tt>build</tt> will need to be listed as
1788 a phony target (i.e., as a dependency of the
1789 <tt>.PHONY</tt> target). See the documentation of
1790 <prgn>make</prgn> for more information on phony
1796 <tag><tt>build-arch</tt> (optional),
1797 <tt>build-indep</tt> (optional)
1801 A package may also provide both of the targets
1802 <tt>build-arch</tt> and <tt>build-indep</tt>.
1803 The <tt>build-arch</tt> target, if provided, should
1804 perform all the configuration and compilation required
1805 for producing all architecture-dependant binary packages
1806 (those packages for which the body of the
1807 <tt>Architecture</tt> field in <tt>debian/control</tt>
1808 is not <tt>all</tt>).
1809 Similarly, the <tt>build-indep</tt> target, if
1810 provided, should perform all the configuration and
1811 compilation required for producing all
1812 architecture-independent binary packages
1813 (those packages for which the body of the
1814 <tt>Architecture</tt> field in <tt>debian/control</tt>
1816 The <tt>build</tt> target should depend on those of the
1817 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1818 are provided in the rules file.
1822 If one or both of the targets <tt>build-arch</tt> and
1823 <tt>build-indep</tt> are not provided, then invoking
1824 <file>debian/rules</file> with one of the not-provided
1825 targets as arguments should produce a exit status code
1826 of 2. Usually this is provided automatically by make
1827 if the target is missing.
1831 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1832 must not do anything that might require root privilege.
1836 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1837 <tt>binary-indep</tt>
1841 The <tt>binary</tt> target must be all that is
1842 necessary for the user to build the binary package(s)
1843 produced from this source package. It is
1844 split into two parts: <prgn>binary-arch</prgn> builds
1845 the binary packages which are specific to a particular
1846 architecture, and <tt>binary-indep</tt> builds
1847 those which are not.
1850 <tt>binary</tt> may be (and commonly is) a target with
1851 no commands which simply depends on
1852 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1855 Both <tt>binary-*</tt> targets should depend on the
1856 <tt>build</tt> target, or on the appropriate
1857 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1858 provided, so that the package is built if it has not
1859 been already. It should then create the relevant
1860 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1861 make their control files and <prgn>dpkg-deb</prgn> to
1862 build them and place them in the parent of the top
1867 Both the <tt>binary-arch</tt> and
1868 <tt>binary-indep</tt> targets <em>must</em> exist.
1869 If one of them has nothing to do (which will always be
1870 the case if the source generates only a single binary
1871 package, whether architecture-dependent or not), it
1872 must still exist and must always succeed.
1876 The <tt>binary</tt> targets must be invoked as
1878 The <prgn>fakeroot</prgn> package often allows one
1879 to build a package correctly even without being
1885 <tag><tt>clean</tt></tag>
1888 This must undo any effects that the <tt>build</tt>
1889 and <tt>binary</tt> targets may have had, except
1890 that it should leave alone any output files created in
1891 the parent directory by a run of a <tt>binary</tt>
1896 If a <tt>build</tt> file is touched at the end of
1897 the <tt>build</tt> target, as suggested above, it
1898 should be removed as the first action that
1899 <tt>clean</tt> performs, so that running
1900 <tt>build</tt> again after an interrupted
1901 <tt>clean</tt> doesn't think that everything is
1906 The <tt>clean</tt> target may need to be
1907 invoked as root if <tt>binary</tt> has been
1908 invoked since the last <tt>clean</tt>, or if
1909 <tt>build</tt> has been invoked as root (since
1910 <tt>build</tt> may create directories, for
1915 <tag><tt>get-orig-source</tt> (optional)</tag>
1918 This target fetches the most recent version of the
1919 original source package from a canonical archive site
1920 (via FTP or WWW, for example), does any necessary
1921 rearrangement to turn it into the original source
1922 tar file format described below, and leaves it in the
1927 This target may be invoked in any directory, and
1928 should take care to clean up any temporary files it
1933 This target is optional, but providing it if
1934 possible is a good idea.
1938 <tag><tt>patch</tt> (optional)</tag>
1941 This target performs whatever additional actions are
1942 required to make the source ready for editing (unpacking
1943 additional upstream archives, applying patches, etc.).
1944 It is recommended to be implemented for any package where
1945 <tt>dpkg-source -x</tt> does not result in source ready
1946 for additional modification. See
1947 <ref id="readmesource">.
1953 The <tt>build</tt>, <tt>binary</tt> and
1954 <tt>clean</tt> targets must be invoked with the current
1955 directory being the package's top-level directory.
1960 Additional targets may exist in <file>debian/rules</file>,
1961 either as published or undocumented interfaces or for the
1962 package's internal use.
1966 The architectures we build on and build for are determined
1967 by <prgn>make</prgn> variables using the utility
1968 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1969 You can determine the
1970 Debian architecture and the GNU style architecture
1971 specification string for the build machine (the machine type
1972 we are building on) as well as for the host machine (the
1973 machine type we are building for). Here is a list of
1974 supported <prgn>make</prgn> variables:
1975 <list compact="compact">
1977 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1980 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1981 specification string)
1984 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
1985 <tt>DEB_*_GNU_TYPE</tt>)
1988 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1989 <tt>DEB_*_GNU_TYPE</tt>)
1991 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1992 the build machine or <tt>HOST</tt> for specification of the
1997 Backward compatibility can be provided in the rules file
1998 by setting the needed variables to suitable default
1999 values; please refer to the documentation of
2000 <prgn>dpkg-architecture</prgn> for details.
2004 It is important to understand that the <tt>DEB_*_ARCH</tt>
2005 string only determines which Debian architecture we are
2006 building on or for. It should not be used to get the CPU
2007 or system information; the GNU style variables should be
2011 <sect1 id="debianrules-options">
2012 <heading><file>debian/rules</file> and
2013 <tt>DEB_BUILD_OPTIONS</tt></heading>
2016 Supporting the standardized environment variable
2017 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2018 contain several flags to change how a package is compiled and
2019 built. Each flag must be in the form <var>flag</var> or
2020 <var>flag</var>=<var>options</var>. If multiple flags are
2021 given, they must be separated by whitespace.<footnote>
2022 Some packages support any delimiter, but whitespace is the
2023 easiest to parse inside a makefile and avoids ambiguity with
2024 flag values that contain commas.
2026 <var>flag</var> must start with a lowercase letter
2027 (<tt>a-z</tt>) and consist only of lowercase letters,
2028 numbers (<tt>0-9</tt>), and the characters
2029 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2030 <var>options</var> must not contain whitespace. The same
2031 tag should not be given multiple times with conflicting
2032 values. Package maintainers may assume that
2033 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2037 The meaning of the following tags has been standardized:
2041 This tag says to not run any build-time test suite
2042 provided by the package.
2046 The presence of this tag means that the package should
2047 be compiled with a minimum of optimization. For C
2048 programs, it is best to add <tt>-O0</tt> to
2049 <tt>CFLAGS</tt> (although this is usually the default).
2050 Some programs might fail to build or run at this level
2051 of optimization; it may be necessary to use
2052 <tt>-O1</tt>, for example.
2056 This tag means that the debugging symbols should not be
2057 stripped from the binary during installation, so that
2058 debugging information may be included in the package.
2060 <tag>parallel=n</tag>
2062 This tag means that the package should be built using up
2063 to <tt>n</tt> parallel processes if the package build
2064 system supports this.<footnote>
2065 Packages built with <tt>make</tt> can often implement
2066 this by passing the <tt>-j</tt><var>n</var> option to
2069 If the package build system does not support parallel
2070 builds, this string must be ignored. If the package
2071 build system only supports a lower level of concurrency
2072 than <var>n</var>, the package should be built using as
2073 many parallel processes as the package build system
2074 supports. It is up to the package maintainer to decide
2075 whether the package build times are long enough and the
2076 package build system is robust enough to make supporting
2077 parallel builds worthwhile.
2083 Unknown flags must be ignored by <file>debian/rules</file>.
2087 The following makefile snippet is an example of how one may
2088 implement the build options; you will probably have to
2089 massage this example in order to make it work for your
2091 <example compact="compact">
2094 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2095 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2096 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2097 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2099 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2104 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2105 INSTALL_PROGRAM += -s
2107 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2108 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2109 MAKEFLAGS += -j$(NUMJOBS)
2114 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2115 # Code to run the package test suite.
2122 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2123 <sect id="substvars">
2124 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2127 When <prgn>dpkg-gencontrol</prgn>,
2128 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2129 generate control files they perform variable substitutions
2130 on their output just before writing it. Variable
2131 substitutions have the form <tt>${<var>variable</var>}</tt>.
2132 The optional file <file>debian/substvars</file> contains
2133 variable substitutions to be used; variables can also be set
2134 directly from <file>debian/rules</file> using the <tt>-V</tt>
2135 option to the source packaging commands, and certain
2136 predefined variables are also available.
2140 The <file>debian/substvars</file> file is usually generated and
2141 modified dynamically by <file>debian/rules</file> targets, in
2142 which case it must be removed by the <tt>clean</tt> target.
2146 See <manref name="deb-substvars" section="5"> for full
2147 details about source variable substitutions, including the
2148 format of <file>debian/substvars</file>.</p>
2151 <sect id="debianwatch">
2152 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2155 This is an optional, recommended control file for the
2156 <tt>uscan</tt> utility which defines how to automatically
2157 scan ftp or http sites for newly available updates of the
2158 package. This is used by <url id="
2159 http://dehs.alioth.debian.org/"> and other Debian QA tools
2160 to help with quality control and maintenance of the
2161 distribution as a whole.
2166 <sect id="debianfiles">
2167 <heading>Generated files list: <file>debian/files</file></heading>
2170 This file is not a permanent part of the source tree; it
2171 is used while building packages to record which files are
2172 being generated. <prgn>dpkg-genchanges</prgn> uses it
2173 when it generates a <file>.changes</file> file.
2177 It should not exist in a shipped source package, and so it
2178 (and any backup files or temporary files such as
2179 <file>files.new</file><footnote>
2180 <file>files.new</file> is used as a temporary file by
2181 <prgn>dpkg-gencontrol</prgn> and
2182 <prgn>dpkg-distaddfile</prgn> - they write a new
2183 version of <tt>files</tt> here before renaming it,
2184 to avoid leaving a corrupted copy if an error
2186 </footnote>) should be removed by the
2187 <tt>clean</tt> target. It may also be wise to
2188 ensure a fresh start by emptying or removing it at the
2189 start of the <tt>binary</tt> target.
2193 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2194 package, it adds an entry to <file>debian/files</file> for the
2195 <file>.deb</file> file that will be created when <tt>dpkg-deb
2196 --build</tt> is run for that binary package. So for most
2197 packages all that needs to be done with this file is to
2198 delete it in the <tt>clean</tt> target.
2202 If a package upload includes files besides the source
2203 package and any binary packages whose control files were
2204 made with <prgn>dpkg-gencontrol</prgn> then they should be
2205 placed in the parent of the package's top-level directory
2206 and <prgn>dpkg-distaddfile</prgn> should be called to add
2207 the file to the list in <file>debian/files</file>.</p>
2210 <sect id="embeddedfiles">
2211 <heading>Convenience copies of code</heading>
2214 Some software packages include in their distribution convenience
2215 copies of code from other software packages, generally so that
2216 users compiling from source don't have to download multiple
2217 packages. Debian packages should not make use of these
2218 convenience copies unless the included package is explicitly
2219 intended to be used in this way.<footnote>
2220 For example, parts of the GNU build system work like this.
2222 If the included code is already in the Debian archive in the
2223 form of a library, the Debian packaging should ensure that
2224 binary packages reference the libraries already in Debian and
2225 the convenience copy is not used. If the included code is not
2226 already in Debian, it should be packaged separately as a
2227 prerequisite if possible.
2229 Having multiple copies of the same code in Debian is
2230 inefficient, often creates either static linking or shared
2231 library conflicts, and, most importantly, increases the
2232 difficulty of handling security vulnerabilities in the
2238 <sect id="readmesource">
2239 <heading>Source package handling:
2240 <file>debian/README.source</file></heading>
2243 If running <prgn>dpkg-source -x</prgn> on a source package
2244 doesn't produce the source of the package, ready for editing,
2245 and allow one to make changes and run
2246 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2247 without taking any additional steps, creating a
2248 <file>debian/README.source</file> documentation file is
2249 recommended. This file should explain how to do all of the
2252 <item>Generate the fully patched source, in a form ready for
2253 editing, that would be built to create Debian
2254 packages. Doing this with a <tt>patch</tt> target in
2255 <file>debian/rules</file> is recommended; see
2256 <ref id="debianrules">.</item>
2257 <item>Modify the source and save those modifications so that
2258 they will be applied when building the package.</item>
2259 <item>Remove source modifications that are currently being
2260 applied when building the package.</item>
2261 <item>Optionally, document what steps are necessary to
2262 upgrade the Debian source package to a new upstream version,
2263 if applicable.</item>
2265 This explanation should include specific commands and mention
2266 any additional required Debian packages. It should not assume
2267 familiarity with any specific Debian packaging system or patch
2272 This explanation may refer to a documentation file installed by
2273 one of the package's build dependencies provided that the
2274 referenced documentation clearly explains these tasks and is not
2275 a general reference manual.
2279 <file>debian/README.source</file> may also include any other
2280 information that would be helpful to someone modifying the
2281 source package. Even if the package doesn't fit the above
2282 description, maintainers are encouraged to document in a
2283 <file>debian/README.source</file> file any source package with a
2284 particularly complex or unintuitive source layout or build
2285 system (for example, a package that builds the same source
2286 multiple times to generate different binary packages).
2292 <chapt id="controlfields">
2293 <heading>Control files and their fields</heading>
2296 The package management system manipulates data represented in
2297 a common format, known as <em>control data</em>, stored in
2298 <em>control files</em>.
2299 Control files are used for source packages, binary packages and
2300 the <file>.changes</file> files which control the installation
2301 of uploaded files<footnote>
2302 <prgn>dpkg</prgn>'s internal databases are in a similar
2307 <sect id="controlsyntax">
2308 <heading>Syntax of control files</heading>
2311 A control file consists of one or more paragraphs of
2313 The paragraphs are also sometimes referred to as stanzas.
2315 The paragraphs are separated by blank lines. Some control
2316 files allow only one paragraph; others allow several, in
2317 which case each paragraph usually refers to a different
2318 package. (For example, in source packages, the first
2319 paragraph refers to the source package, and later paragraphs
2320 refer to binary packages generated from the source.)
2324 Each paragraph consists of a series of data fields; each
2325 field consists of the field name, followed by a colon and
2326 then the data/value associated with that field. It ends at
2327 the end of the (logical) line. Horizontal whitespace
2328 (spaces and tabs) may occur immediately before or after the
2329 value and is ignored there; it is conventional to put a
2330 single space after the colon. For example, a field might
2332 <example compact="compact">
2335 the field name is <tt>Package</tt> and the field value
2340 Many fields' values may span several lines; in this case
2341 each continuation line must start with a space or a tab.
2342 Any trailing spaces or tabs at the end of individual
2343 lines of a field value are ignored.
2347 In fields where it is specified that lines may not wrap,
2348 only a single line of data is allowed and whitespace is not
2349 significant in a field body. Whitespace must not appear
2350 inside names (of packages, architectures, files or anything
2351 else) or version numbers, or between the characters of
2352 multi-character version relationships.
2356 Field names are not case-sensitive, but it is usual to
2357 capitalize the field names using mixed case as shown below.
2361 Blank lines, or lines consisting only of spaces and tabs,
2362 are not allowed within field values or between fields - that
2363 would mean a new paragraph.
2367 All control files must be encoded in UTF-8.
2371 <sect id="sourcecontrolfiles">
2372 <heading>Source package control files -- <file>debian/control</file></heading>
2375 The <file>debian/control</file> file contains the most vital
2376 (and version-independent) information about the source package
2377 and about the binary packages it creates.
2381 The first paragraph of the control file contains information about
2382 the source package in general. The subsequent sets each describe a
2383 binary package that the source tree builds.
2387 The fields in the general paragraph (the first one, for the source
2390 <list compact="compact">
2391 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2392 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2393 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2394 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2395 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2396 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2397 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2398 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2403 The fields in the binary package paragraphs are:
2405 <list compact="compact">
2406 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2407 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2408 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2409 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2410 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2411 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2412 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2413 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2418 The syntax and semantics of the fields are described below.
2424 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2425 generate control files for binary packages (see below), by
2426 <prgn>dpkg-genchanges</prgn> to generate the
2427 <tt>.changes</tt> file to accompany the upload, and by
2428 <prgn>dpkg-source</prgn> when it creates the
2429 <file>.dsc</file> source control file as part of a source
2430 archive. Many fields are permitted to span multiple lines in
2431 <file>debian/control</file> but not in any other control
2432 file. These tools are responsible for removing the line
2433 breaks from such fields when using fields from
2434 <file>debian/control</file> to generate other control files.
2438 The fields here may contain variable references - their
2439 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2440 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2441 when they generate output control files.
2442 See <ref id="substvars"> for details.
2447 <sect id="binarycontrolfiles">
2448 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2451 The <file>DEBIAN/control</file> file contains the most vital
2452 (and version-dependent) information about a binary package.
2456 The fields in this file are:
2458 <list compact="compact">
2459 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2460 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2461 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2462 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2463 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2464 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2465 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2466 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2467 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2468 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2469 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2470 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2475 <sect id="debiansourcecontrolfiles">
2476 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2479 This file contains a series of fields, identified and
2480 separated just like the fields in the control file of
2481 a binary package. The fields are listed below; their
2482 syntax is described above, in <ref id="pkg-controlfields">.
2484 <list compact="compact">
2485 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2486 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2487 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2488 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2489 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2490 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2491 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2492 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2493 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2494 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2495 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2500 The source package control file is generated by
2501 <prgn>dpkg-source</prgn> when it builds the source
2502 archive, from other files in the source package,
2503 described above. When unpacking, it is checked against
2504 the files and directories in the other parts of the
2510 <sect id="debianchangesfiles">
2511 <heading>Debian changes files -- <file>.changes</file></heading>
2514 The .changes files are used by the Debian archive maintenance
2515 software to process updates to packages. They contain one
2516 paragraph which contains information from the
2517 <tt>debian/control</tt> file and other data about the
2518 source package gathered via <tt>debian/changelog</tt>
2519 and <tt>debian/rules</tt>.
2523 The fields in this file are:
2525 <list compact="compact">
2526 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2527 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2528 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2529 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2530 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2531 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2532 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2533 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2534 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2535 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2536 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2537 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2538 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2539 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2544 <sect id="controlfieldslist">
2545 <heading>List of fields</heading>
2547 <sect1 id="f-Source">
2548 <heading><tt>Source</tt></heading>
2551 This field identifies the source package name.
2555 In <file>debian/control</file> or a <file>.dsc</file> file,
2556 this field must contain only the name of the source package.
2560 In a binary package control file or a <file>.changes</file>
2561 file, the source package name may be followed by a version
2562 number in parentheses<footnote>
2563 It is customary to leave a space after the package name
2564 if a version number is specified.
2566 This version number may be omitted (and is, by
2567 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2568 the <tt>Version</tt> field of the binary package in
2569 question. The field itself may be omitted from a binary
2570 package control file when the source package has the same
2571 name and version as the binary package.
2575 <sect1 id="f-Maintainer">
2576 <heading><tt>Maintainer</tt></heading>
2579 The package maintainer's name and email address. The name
2580 should come first, then the email address inside angle
2581 brackets <tt><></tt> (in RFC822 format).
2585 If the maintainer's name contains a full stop then the
2586 whole field will not work directly as an email address due
2587 to a misfeature in the syntax specified in RFC822; a
2588 program using this field as an address must check for this
2589 and correct the problem if necessary (for example by
2590 putting the name in round brackets and moving it to the
2591 end, and bringing the email address forward).
2595 <sect1 id="f-Uploaders">
2596 <heading><tt>Uploaders</tt></heading>
2599 List of the names and email addresses of co-maintainers of
2600 the package, if any. If the package has other maintainers
2601 beside the one named in the
2602 <qref id="f-Maintainer">Maintainer field</qref>, their
2603 names and email addresses should be listed here. The
2604 format is the same as that of the Maintainer tag, and
2605 multiple entries should be comma separated. Currently,
2606 this field is restricted to a single line of data. This
2607 is an optional field.
2610 Any parser that interprets the Uploaders field in
2611 <file>debian/control</file> must permit it to span multiple
2612 lines. Line breaks in an Uploaders field that spans multiple
2613 lines are not significant and the semantics of the field are
2614 the same as if the line breaks had not been present.
2618 <sect1 id="f-Changed-By">
2619 <heading><tt>Changed-By</tt></heading>
2622 The name and email address of the person who changed the
2623 said package. Usually the name of the maintainer.
2624 All the rules for the Maintainer field apply here, too.
2628 <sect1 id="f-Section">
2629 <heading><tt>Section</tt></heading>
2632 This field specifies an application area into which the package
2633 has been classified. See <ref id="subsections">.
2637 When it appears in the <file>debian/control</file> file,
2638 it gives the value for the subfield of the same name in
2639 the <tt>Files</tt> field of the <file>.changes</file> file.
2640 It also gives the default for the same field in the binary
2645 <sect1 id="f-Priority">
2646 <heading><tt>Priority</tt></heading>
2649 This field represents how important that it is that the user
2650 have the package installed. See <ref id="priorities">.
2654 When it appears in the <file>debian/control</file> file,
2655 it gives the value for the subfield of the same name in
2656 the <tt>Files</tt> field of the <file>.changes</file> file.
2657 It also gives the default for the same field in the binary
2662 <sect1 id="f-Package">
2663 <heading><tt>Package</tt></heading>
2666 The name of the binary package.
2670 Package names must consist only of lower case letters
2671 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2672 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2673 They must be at least two characters long and must start
2674 with an alphanumeric character.
2678 <sect1 id="f-Architecture">
2679 <heading><tt>Architecture</tt></heading>
2682 Depending on context and the control file used, the
2683 <tt>Architecture</tt> field can include the following sets of
2686 <item>A unique single word identifying a Debian machine
2687 architecture, see <ref id="arch-spec">.
2688 <item><tt>all</tt>, which indicates an
2689 architecture-independent package.
2690 <item><tt>any</tt>, which indicates a package available
2691 for building on any architecture.
2692 <item><tt>source</tt>, which indicates a source package.
2697 In the main <file>debian/control</file> file in the source
2698 package, or in the source package control file
2699 <file>.dsc</file>, one may specify a list of architectures
2700 separated by spaces, or the special values <tt>any</tt> or
2705 Specifying <tt>any</tt> indicates that the source package
2706 isn't dependent on any particular architecture and should
2707 compile fine on any one. The produced binary package(s)
2708 will be specific to whatever the current build architecture
2710 This is the most often used setting, and is recommended
2711 for new packages that aren't <tt>Architecture: all</tt>.
2716 Specifying a list of architectures indicates that the source
2717 will build an architecture-dependent package, and will only
2718 work correctly on the listed architectures.<footnote>
2719 This is a setting used for a minority of cases where the
2720 program is not portable. Generally, it should not be used
2726 In a <file>.changes</file> file, the <tt>Architecture</tt>
2727 field lists the architecture(s) of the package(s)
2728 currently being uploaded. This will be a list; if the
2729 source for the package is also being uploaded, the special
2730 entry <tt>source</tt> is also present.
2734 See <ref id="debianrules"> for information how to get the
2735 architecture for the build process.
2739 <sect1 id="f-Essential">
2740 <heading><tt>Essential</tt></heading>
2743 This is a boolean field which may occur only in the
2744 control file of a binary package or in a per-package fields
2745 paragraph of a main source control data file.
2749 If set to <tt>yes</tt> then the package management system
2750 will refuse to remove the package (upgrading and replacing
2751 it is still possible). The other possible value is <tt>no</tt>,
2752 which is the same as not having the field at all.
2757 <heading>Package interrelationship fields:
2758 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2759 <tt>Recommends</tt>, <tt>Suggests</tt>,
2760 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2761 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2765 These fields describe the package's relationships with
2766 other packages. Their syntax and semantics are described
2767 in <ref id="relationships">.</p>
2770 <sect1 id="f-Standards-Version">
2771 <heading><tt>Standards-Version</tt></heading>
2774 The most recent version of the standards (the policy
2775 manual and associated texts) with which the package
2780 The version number has four components: major and minor
2781 version number and major and minor patch level. When the
2782 standards change in a way that requires every package to
2783 change the major number will be changed. Significant
2784 changes that will require work in many packages will be
2785 signaled by a change to the minor number. The major patch
2786 level will be changed for any change to the meaning of the
2787 standards, however small; the minor patch level will be
2788 changed when only cosmetic, typographical or other edits
2789 are made which neither change the meaning of the document
2790 nor affect the contents of packages.
2794 Thus only the first three components of the policy version
2795 are significant in the <em>Standards-Version</em> control
2796 field, and so either these three components or the all
2797 four components may be specified.<footnote>
2798 In the past, people specified the full version number
2799 in the Standards-Version field, for example "2.3.0.0".
2800 Since minor patch-level changes don't introduce new
2801 policy, it was thought it would be better to relax
2802 policy and only require the first 3 components to be
2803 specified, in this example "2.3.0". All four
2804 components may still be used if someone wishes to do so.
2810 <sect1 id="f-Version">
2811 <heading><tt>Version</tt></heading>
2814 The version number of a package. The format is:
2815 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2819 The three components here are:
2821 <tag><var>epoch</var></tag>
2824 This is a single (generally small) unsigned integer. It
2825 may be omitted, in which case zero is assumed. If it is
2826 omitted then the <var>upstream_version</var> may not
2831 It is provided to allow mistakes in the version numbers
2832 of older versions of a package, and also a package's
2833 previous version numbering schemes, to be left behind.
2837 <tag><var>upstream_version</var></tag>
2840 This is the main part of the version number. It is
2841 usually the version number of the original ("upstream")
2842 package from which the <file>.deb</file> file has been made,
2843 if this is applicable. Usually this will be in the same
2844 format as that specified by the upstream author(s);
2845 however, it may need to be reformatted to fit into the
2846 package management system's format and comparison
2851 The comparison behavior of the package management system
2852 with respect to the <var>upstream_version</var> is
2853 described below. The <var>upstream_version</var>
2854 portion of the version number is mandatory.
2858 The <var>upstream_version</var> may contain only
2859 alphanumerics<footnote>
2860 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2862 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2863 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2864 tilde) and should start with a digit. If there is no
2865 <var>debian_revision</var> then hyphens are not allowed;
2866 if there is no <var>epoch</var> then colons are not
2871 <tag><var>debian_revision</var></tag>
2874 This part of the version number specifies the version of
2875 the Debian package based on the upstream version. It
2876 may contain only alphanumerics and the characters
2877 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2878 tilde) and is compared in the same way as the
2879 <var>upstream_version</var> is.
2883 It is optional; if it isn't present then the
2884 <var>upstream_version</var> may not contain a hyphen.
2885 This format represents the case where a piece of
2886 software was written specifically to be turned into a
2887 Debian package, and so there is only one "debianisation"
2888 of it and therefore no revision indication is required.
2892 It is conventional to restart the
2893 <var>debian_revision</var> at <tt>1</tt> each time the
2894 <var>upstream_version</var> is increased.
2898 The package management system will break the version
2899 number apart at the last hyphen in the string (if there
2900 is one) to determine the <var>upstream_version</var> and
2901 <var>debian_revision</var>. The absence of a
2902 <var>debian_revision</var> is equivalent to a
2903 <var>debian_revision</var> of <tt>0</tt>.
2910 When comparing two version numbers, first the <var>epoch</var>
2911 of each are compared, then the <var>upstream_version</var> if
2912 <var>epoch</var> is equal, and then <var>debian_revision</var>
2913 if <var>upstream_version</var> is also equal.
2914 <var>epoch</var> is compared numerically. The
2915 <var>upstream_version</var> and <var>debian_revision</var>
2916 parts are compared by the package management system using the
2917 following algorithm:
2921 The strings are compared from left to right.
2925 First the initial part of each string consisting entirely of
2926 non-digit characters is determined. These two parts (one of
2927 which may be empty) are compared lexically. If a difference
2928 is found it is returned. The lexical comparison is a
2929 comparison of ASCII values modified so that all the letters
2930 sort earlier than all the non-letters and so that a tilde
2931 sorts before anything, even the end of a part. For example,
2932 the following parts are in sorted order from earliest to
2933 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
2934 <tt>a</tt>.<footnote>
2935 One common use of <tt>~</tt> is for upstream pre-releases.
2936 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
2937 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
2942 Then the initial part of the remainder of each string which
2943 consists entirely of digit characters is determined. The
2944 numerical values of these two parts are compared, and any
2945 difference found is returned as the result of the comparison.
2946 For these purposes an empty string (which can only occur at
2947 the end of one or both version strings being compared) counts
2952 These two steps (comparing and removing initial non-digit
2953 strings and initial digit strings) are repeated until a
2954 difference is found or both strings are exhausted.
2958 Note that the purpose of epochs is to allow us to leave behind
2959 mistakes in version numbering, and to cope with situations
2960 where the version numbering scheme changes. It is
2961 <em>not</em> intended to cope with version numbers containing
2962 strings of letters which the package management system cannot
2963 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2964 silly orderings (the author of this manual has heard of a
2965 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2966 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2967 <tt>2</tt> and so forth).
2971 <sect1 id="f-Description">
2972 <heading><tt>Description</tt></heading>
2975 In a source or binary control file, the <tt>Description</tt>
2976 field contains a description of the binary package, consisting
2977 of two parts, the synopsis or the short description, and the
2978 long description. The field's format is as follows:
2983 Description: <single line synopsis>
2984 <extended description over several lines>
2989 The lines in the extended description can have these formats:
2995 Those starting with a single space are part of a paragraph.
2996 Successive lines of this form will be word-wrapped when
2997 displayed. The leading space will usually be stripped off.
3001 Those starting with two or more spaces. These will be
3002 displayed verbatim. If the display cannot be panned
3003 horizontally, the displaying program will line wrap them "hard"
3004 (i.e., without taking account of word breaks). If it can they
3005 will be allowed to trail off to the right. None, one or two
3006 initial spaces may be deleted, but the number of spaces
3007 deleted from each line will be the same (so that you can have
3008 indenting work correctly, for example).
3012 Those containing a single space followed by a single full stop
3013 character. These are rendered as blank lines. This is the
3014 <em>only</em> way to get a blank line<footnote>
3015 Completely empty lines will not be rendered as blank lines.
3016 Instead, they will cause the parser to think you're starting
3017 a whole new record in the control file, and will therefore
3018 likely abort with an error.
3023 Those containing a space, a full stop and some more characters.
3024 These are for future expansion. Do not use them.
3030 Do not use tab characters. Their effect is not predictable.
3034 See <ref id="descriptions"> for further information on this.
3038 In a <file>.changes</file> file, the <tt>Description</tt> field
3039 contains a summary of the descriptions for the packages being
3044 The part of the field before the first newline is empty;
3045 thereafter each line has the name of a binary package and
3046 the summary description line from that binary package.
3047 Each line is indented by one space.
3052 <sect1 id="f-Distribution">
3053 <heading><tt>Distribution</tt></heading>
3056 In a <file>.changes</file> file or parsed changelog output
3057 this contains the (space-separated) name(s) of the
3058 distribution(s) where this version of the package should
3059 be installed. Valid distributions are determined by the
3060 archive maintainers.<footnote>
3061 Current distribution names are:
3062 <taglist compact="compact">
3063 <tag><em>stable</em></tag>
3065 This is the current "released" version of Debian
3066 GNU/Linux. Once the distribution is
3067 <em>stable</em> only security fixes and other
3068 major bug fixes are allowed. When changes are
3069 made to this distribution, the release number is
3070 increased (for example: 2.2r1 becomes 2.2r2 then
3074 <tag><em>unstable</em></tag>
3076 This distribution value refers to the
3077 <em>developmental</em> part of the Debian
3078 distribution tree. New packages, new upstream
3079 versions of packages and bug fixes go into the
3080 <em>unstable</em> directory tree. Download from
3081 this distribution at your own risk.
3084 <tag><em>testing</em></tag>
3086 This distribution value refers to the
3087 <em>testing</em> part of the Debian distribution
3088 tree. It receives its packages from the
3089 unstable distribution after a short time lag to
3090 ensure that there are no major issues with the
3091 unstable packages. It is less prone to breakage
3092 than unstable, but still risky. It is not
3093 possible to upload packages directly to
3097 <tag><em>frozen</em></tag>
3099 From time to time, the <em>testing</em>
3100 distribution enters a state of "code-freeze" in
3101 anticipation of release as a <em>stable</em>
3102 version. During this period of testing only
3103 fixes for existing or newly-discovered bugs will
3104 be allowed. The exact details of this stage are
3105 determined by the Release Manager.
3108 <tag><em>experimental</em></tag>
3110 The packages with this distribution value are
3111 deemed by their maintainers to be high
3112 risk. Oftentimes they represent early beta or
3113 developmental packages from various sources that
3114 the maintainers want people to try, but are not
3115 ready to be a part of the other parts of the
3116 Debian distribution tree. Download at your own
3122 You should list <em>all</em> distributions that the
3123 package should be installed into.
3127 More information is available in the Debian Developer's
3128 Reference, section "The Debian archive".
3135 <heading><tt>Date</tt></heading>
3138 This field includes the date the package was built or last edited.
3142 The value of this field is usually extracted from the
3143 <file>debian/changelog</file> file - see
3144 <ref id="dpkgchangelog">).
3148 <sect1 id="f-Format">
3149 <heading><tt>Format</tt></heading>
3152 This field specifies a format revision for the file.
3153 The most current format described in the Policy Manual
3154 is version <strong>1.5</strong>. The syntax of the
3155 format value is the same as that of a package version
3156 number except that no epoch or Debian revision is allowed
3157 - see <ref id="f-Version">.
3161 <sect1 id="f-Urgency">
3162 <heading><tt>Urgency</tt></heading>
3165 This is a description of how important it is to upgrade to
3166 this version from previous ones. It consists of a single
3167 keyword taking one of the values <tt>low</tt>,
3168 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3169 <tt>critical</tt><footnote>
3170 Other urgency values are supported with configuration
3171 changes in the archive software but are not used in Debian.
3172 The urgency affects how quickly a package will be considered
3173 for inclusion into the <tt>testing</tt> distribution and
3174 gives an indication of the importance of any fixes included
3175 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3176 treated as synonymous.
3177 </footnote> (not case-sensitive) followed by an optional
3178 commentary (separated by a space) which is usually in
3179 parentheses. For example:
3182 Urgency: low (HIGH for users of diversions)
3188 The value of this field is usually extracted from the
3189 <file>debian/changelog</file> file - see
3190 <ref id="dpkgchangelog">.
3194 <sect1 id="f-Changes">
3195 <heading><tt>Changes</tt></heading>
3198 This field contains the human-readable changes data, describing
3199 the differences between the last version and the current one.
3203 There should be nothing in this field before the first
3204 newline; all the subsequent lines must be indented by at
3205 least one space; blank lines must be represented by a line
3206 consisting only of a space and a full stop.
3210 The value of this field is usually extracted from the
3211 <file>debian/changelog</file> file - see
3212 <ref id="dpkgchangelog">).
3216 Each version's change information should be preceded by a
3217 "title" line giving at least the version, distribution(s)
3218 and urgency, in a human-readable way.
3222 If data from several versions is being returned the entry
3223 for the most recent version should be returned first, and
3224 entries should be separated by the representation of a
3225 blank line (the "title" line may also be followed by the
3226 representation of blank line).
3230 <sect1 id="f-Binary">
3231 <heading><tt>Binary</tt></heading>
3234 This field is a list of binary packages.
3238 When it appears in the <file>.dsc</file> file it is the list
3239 of binary packages which a source package can produce. It
3240 does not necessarily produce all of these binary packages
3241 for every architecture. The source control file doesn't
3242 contain details of which architectures are appropriate for
3243 which of the binary packages.
3247 When it appears in a <file>.changes</file> file it lists the
3248 names of the binary packages actually being uploaded.
3252 The syntax is a list of binary packages separated by
3254 A space after each comma is conventional.
3255 </footnote>. Currently the packages must be separated using
3256 only spaces in the <file>.changes</file> file.
3260 <sect1 id="f-Installed-Size">
3261 <heading><tt>Installed-Size</tt></heading>
3264 This field appears in the control files of binary
3265 packages, and in the <file>Packages</file> files. It gives
3266 the total amount of disk space required to install the
3271 The disk space is represented in kilobytes as a simple
3276 <sect1 id="f-Files">
3277 <heading><tt>Files</tt></heading>
3280 This field contains a list of files with information about
3281 each one. The exact information and syntax varies with
3282 the context. In all cases the part of the field
3283 contents on the same line as the field name is empty. The
3284 remainder of the field is one line per file, each line
3285 being indented by one space and containing a number of
3286 sub-fields separated by spaces.
3290 In the <file>.dsc</file> file, each line contains the MD5
3291 checksum, size and filename of the tar file and (if applicable)
3292 diff file which make up the remainder of the source
3294 That is, the parts which are not the <tt>.dsc</tt>.
3296 The exact forms of the filenames are described
3297 in <ref id="pkg-sourcearchives">.
3301 In the <file>.changes</file> file this contains one line per
3302 file being uploaded. Each line contains the MD5 checksum,
3303 size, section and priority and the filename.
3304 The <qref id="f-Section">section</qref>
3305 and <qref id="f-Priority">priority</qref>
3306 are the values of the corresponding fields in
3307 the main source control file. If no section or priority is
3308 specified then <tt>-</tt> should be used, though section
3309 and priority values must be specified for new packages to
3310 be installed properly.
3314 The special value <tt>byhand</tt> for the section in a
3315 <tt>.changes</tt> file indicates that the file in question
3316 is not an ordinary package file and must by installed by
3317 hand by the distribution maintainers. If the section is
3318 <tt>byhand</tt> the priority should be <tt>-</tt>.
3322 If a new Debian revision of a package is being shipped and
3323 no new original source archive is being distributed the
3324 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3325 entry for the original source archive
3326 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3327 but the <file>.changes</file> file should leave it out. In
3328 this case the original source archive on the distribution
3329 site must match exactly, byte-for-byte, the original
3330 source archive which was used to generate the
3331 <file>.dsc</file> file and diff which are being uploaded.</p>
3334 <sect1 id="f-Closes">
3335 <heading><tt>Closes</tt></heading>
3338 A space-separated list of bug report numbers that the upload
3339 governed by the .changes file closes.
3343 <sect1 id="f-Homepage">
3344 <heading><tt>Homepage</tt></heading>
3347 The URL of the web site for this package, preferably (when
3348 applicable) the site from which the original source can be
3349 obtained and any additional upstream documentation or
3350 information may be found. The content of this field is a
3351 simple URL without any surrounding characters such as
3359 <heading>User-defined fields</heading>
3362 Additional user-defined fields may be added to the
3363 source package control file. Such fields will be
3364 ignored, and not copied to (for example) binary or
3365 source package control files or upload control files.
3369 If you wish to add additional unsupported fields to
3370 these output files you should use the mechanism
3375 Fields in the main source control information file with
3376 names starting <tt>X</tt>, followed by one or more of
3377 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3378 be copied to the output files. Only the part of the
3379 field name after the hyphen will be used in the output
3380 file. Where the letter <tt>B</tt> is used the field
3381 will appear in binary package control files, where the
3382 letter <tt>S</tt> is used in source package control
3383 files and where <tt>C</tt> is used in upload control
3384 (<tt>.changes</tt>) files.
3388 For example, if the main source information control file
3391 XBS-Comment: I stand between the candle and the star.
3393 then the binary and source package control files will contain the
3396 Comment: I stand between the candle and the star.
3405 <chapt id="maintainerscripts">
3406 <heading>Package maintainer scripts and installation procedure</heading>
3409 <heading>Introduction to package maintainer scripts</heading>
3412 It is possible to supply scripts as part of a package which
3413 the package management system will run for you when your
3414 package is installed, upgraded or removed.
3418 These scripts are the files <prgn>preinst</prgn>,
3419 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3420 <prgn>postrm</prgn> in the control area of the package.
3421 They must be proper executable files; if they are scripts
3422 (which is recommended), they must start with the usual
3423 <tt>#!</tt> convention. They should be readable and
3424 executable by anyone, and must not be world-writable.
3428 The package management system looks at the exit status from
3429 these scripts. It is important that they exit with a
3430 non-zero status if there is an error, so that the package
3431 management system can stop its processing. For shell
3432 scripts this means that you <em>almost always</em> need to
3433 use <tt>set -e</tt> (this is usually true when writing shell
3434 scripts, in fact). It is also important, of course, that
3435 they don't exit with a non-zero status if everything went
3440 Additionally, packages interacting with users using
3441 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3442 install a <prgn>config</prgn> script in the control area,
3443 see <ref id="maintscriptprompt"> for details.
3447 When a package is upgraded a combination of the scripts from
3448 the old and new packages is called during the upgrade
3449 procedure. If your scripts are going to be at all
3450 complicated you need to be aware of this, and may need to
3451 check the arguments to your scripts.
3455 Broadly speaking the <prgn>preinst</prgn> is called before
3456 (a particular version of) a package is installed, and the
3457 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3458 before (a version of) a package is removed and the
3459 <prgn>postrm</prgn> afterwards.
3463 Programs called from maintainer scripts should not normally
3464 have a path prepended to them. Before installation is
3465 started, the package management system checks to see if the
3466 programs <prgn>ldconfig</prgn>,
3467 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3468 and <prgn>update-rc.d</prgn> can be found via the
3469 <tt>PATH</tt> environment variable. Those programs, and any
3470 other program that one would expect to be in the
3471 <tt>PATH</tt>, should thus be invoked without an absolute
3472 pathname. Maintainer scripts should also not reset the
3473 <tt>PATH</tt>, though they might choose to modify it by
3474 prepending or appending package-specific directories. These
3475 considerations really apply to all shell scripts.</p>
3478 <sect id="idempotency">
3479 <heading>Maintainer scripts idempotency</heading>
3482 It is necessary for the error recovery procedures that the
3483 scripts be idempotent. This means that if it is run
3484 successfully, and then it is called again, it doesn't bomb
3485 out or cause any harm, but just ensures that everything is
3486 the way it ought to be. If the first call failed, or
3487 aborted half way through for some reason, the second call
3488 should merely do the things that were left undone the first
3489 time, if any, and exit with a success status if everything
3491 This is so that if an error occurs, the user interrupts
3492 <prgn>dpkg</prgn> or some other unforeseen circumstance
3493 happens you don't leave the user with a badly-broken
3494 package when <prgn>dpkg</prgn> attempts to repeat the
3500 <sect id="controllingterminal">
3501 <heading>Controlling terminal for maintainer scripts</heading>
3504 The maintainer scripts are guaranteed to run with a
3505 controlling terminal and can interact with the user.
3506 Because these scripts may be executed with standard output
3507 redirected into a pipe for logging purposes, Perl scripts
3508 should set unbuffered output by setting <tt>$|=1</tt> so
3509 that the output is printed immediately rather than being
3513 <sect id="exitstatus">
3514 <heading>Exit status</heading>
3517 Each script must return a zero exit status for
3518 success, or a nonzero one for failure, since the package
3519 management system looks for the exit status of these scripts
3520 and determines what action to take next based on that datum.
3524 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3529 <list compact="compact">
3531 <var>new-preinst</var> <tt>install</tt>
3534 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3537 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3540 <var>old-preinst</var> <tt>abort-upgrade</tt>
3541 <var>new-version</var>
3546 <list compact="compact">
3548 <var>postinst</var> <tt>configure</tt>
3549 <var>most-recently-configured-version</var>
3552 <var>old-postinst</var> <tt>abort-upgrade</tt>
3553 <var>new-version</var>
3556 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3557 <tt>in-favour</tt> <var>package</var>
3558 <var>new-version</var>
3561 <var>postinst</var> <tt>abort-remove</tt>
3564 <var>deconfigured's-postinst</var>
3565 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3566 <var>failed-install-package</var> <var>version</var>
3567 [<tt>removing</tt> <var>conflicting-package</var>
3573 <list compact="compact">
3575 <var>prerm</var> <tt>remove</tt>
3578 <var>old-prerm</var> <tt>upgrade</tt>
3579 <var>new-version</var>
3582 <var>new-prerm</var> <tt>failed-upgrade</tt>
3583 <var>old-version</var>
3586 <var>conflictor's-prerm</var> <tt>remove</tt>
3587 <tt>in-favour</tt> <var>package</var>
3588 <var>new-version</var>
3591 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3592 <tt>in-favour</tt> <var>package-being-installed</var>
3593 <var>version</var> [<tt>removing</tt>
3594 <var>conflicting-package</var>
3600 <list compact="compact">
3602 <var>postrm</var> <tt>remove</tt>
3605 <var>postrm</var> <tt>purge</tt>
3608 <var>old-postrm</var> <tt>upgrade</tt>
3609 <var>new-version</var>
3612 <var>new-postrm</var> <tt>failed-upgrade</tt>
3613 <var>old-version</var>
3616 <var>new-postrm</var> <tt>abort-install</tt>
3619 <var>new-postrm</var> <tt>abort-install</tt>
3620 <var>old-version</var>
3623 <var>new-postrm</var> <tt>abort-upgrade</tt>
3624 <var>old-version</var>
3627 <var>disappearer's-postrm</var> <tt>disappear</tt>
3628 <var>overwriter</var>
3629 <var>overwriter-version</var>
3635 <sect id="unpackphase">
3636 <heading>Details of unpack phase of installation or upgrade</heading>
3639 The procedure on installation/upgrade/overwrite/disappear
3640 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3641 stage of <tt>dpkg --install</tt>) is as follows. In each
3642 case, if a major error occurs (unless listed below) the
3643 actions are, in general, run backwards - this means that the
3644 maintainer scripts are run with different arguments in
3645 reverse order. These are the "error unwind" calls listed
3652 If a version of the package is already installed, call
3653 <example compact="compact">
3654 <var>old-prerm</var> upgrade <var>new-version</var>
3658 If the script runs but exits with a non-zero
3659 exit status, <prgn>dpkg</prgn> will attempt:
3660 <example compact="compact">
3661 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3663 If this works, the upgrade continues. If this
3664 does not work, the error unwind:
3665 <example compact="compact">
3666 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3668 If this works, then the old-version is
3669 "Installed", if not, the old version is in a
3670 "Failed-Config" state.
3676 If a "conflicting" package is being removed at the same time,
3677 or if any package will be broken (due to <tt>Breaks</tt>):
3680 If <tt>--auto-deconfigure</tt> is
3681 specified, call, for each package to be deconfigured
3682 due to <tt>Breaks</tt>:
3683 <example compact="compact">
3684 <var>deconfigured's-prerm</var> deconfigure \
3685 in-favour <var>package-being-installed</var> <var>version</var>
3688 <example compact="compact">
3689 <var>deconfigured's-postinst</var> abort-deconfigure \
3690 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3692 The deconfigured packages are marked as
3693 requiring configuration, so that if
3694 <tt>--install</tt> is used they will be
3695 configured again if possible.
3698 If any packages depended on a conflicting
3699 package being removed and <tt>--auto-deconfigure</tt> is
3700 specified, call, for each such package:
3701 <example compact="compact">
3702 <var>deconfigured's-prerm</var> deconfigure \
3703 in-favour <var>package-being-installed</var> <var>version</var> \
3704 removing <var>conflicting-package</var> <var>version</var>
3707 <example compact="compact">
3708 <var>deconfigured's-postinst</var> abort-deconfigure \
3709 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3710 removing <var>conflicting-package</var> <var>version</var>
3712 The deconfigured packages are marked as
3713 requiring configuration, so that if
3714 <tt>--install</tt> is used they will be
3715 configured again if possible.
3718 To prepare for removal of each conflicting package, call:
3719 <example compact="compact">
3720 <var>conflictor's-prerm</var> remove \
3721 in-favour <var>package</var> <var>new-version</var>
3724 <example compact="compact">
3725 <var>conflictor's-postinst</var> abort-remove \
3726 in-favour <var>package</var> <var>new-version</var>
3735 If the package is being upgraded, call:
3736 <example compact="compact">
3737 <var>new-preinst</var> upgrade <var>old-version</var>
3739 If this fails, we call:
3741 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3748 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3750 is called. If this works, then the old version
3751 is in an "Installed" state, or else it is left
3752 in an "Unpacked" state.
3757 If it fails, then the old version is left
3758 in an "Half-Installed" state.
3765 Otherwise, if the package had some configuration
3766 files from a previous version installed (i.e., it
3767 is in the "configuration files only" state):
3768 <example compact="compact">
3769 <var>new-preinst</var> install <var>old-version</var>
3773 <var>new-postrm</var> abort-install <var>old-version</var>
3775 If this fails, the package is left in a
3776 "Half-Installed" state, which requires a
3777 reinstall. If it works, the packages is left in
3778 a "Config Files" state.
3781 Otherwise (i.e., the package was completely purged):
3782 <example compact="compact">
3783 <var>new-preinst</var> install
3786 <example compact="compact">
3787 <var>new-postrm</var> abort-install
3789 If the error-unwind fails, the package is in a
3790 "Half Installed" phase, and requires a
3791 reinstall. If the error unwind works, the
3792 package is in a not installed state.
3799 The new package's files are unpacked, overwriting any
3800 that may be on the system already, for example any
3801 from the old version of the same package or from
3802 another package. Backups of the old files are kept
3803 temporarily, and if anything goes wrong the package
3804 management system will attempt to put them back as
3805 part of the error unwind.
3809 It is an error for a package to contain files which
3810 are on the system in another package, unless
3811 <tt>Replaces</tt> is used (see <ref id="replaces">).
3813 The following paragraph is not currently the case:
3814 Currently the <tt>- - force-overwrite</tt> flag is
3815 enabled, downgrading it to a warning, but this may not
3821 It is a more serious error for a package to contain a
3822 plain file or other kind of non-directory where another
3823 package has a directory (again, unless
3824 <tt>Replaces</tt> is used). This error can be
3825 overridden if desired using
3826 <tt>--force-overwrite-dir</tt>, but this is not
3831 Packages which overwrite each other's files produce
3832 behavior which, though deterministic, is hard for the
3833 system administrator to understand. It can easily
3834 lead to "missing" programs if, for example, a package
3835 is installed which overwrites a file from another
3836 package, and is then removed again.<footnote>
3837 Part of the problem is due to what is arguably a
3838 bug in <prgn>dpkg</prgn>.
3843 A directory will never be replaced by a symbolic link
3844 to a directory or vice versa; instead, the existing
3845 state (symlink or not) will be left alone and
3846 <prgn>dpkg</prgn> will follow the symlink if there is
3855 If the package is being upgraded, call
3856 <example compact="compact">
3857 <var>old-postrm</var> upgrade <var>new-version</var>
3861 If this fails, <prgn>dpkg</prgn> will attempt:
3862 <example compact="compact">
3863 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3865 If this works, installation continues. If not,
3867 <example compact="compact">
3868 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3870 If this fails, the old version is left in an
3871 "Half Installed" state. If it works, dpkg now
3873 <example compact="compact">
3874 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3876 If this fails, the old version is left in an
3877 "Half Installed" state. If it works, dpkg now
3879 <example compact="compact">
3880 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3882 If this fails, the old version is in an
3889 This is the point of no return - if
3890 <prgn>dpkg</prgn> gets this far, it won't back off
3891 past this point if an error occurs. This will
3892 leave the package in a fairly bad state, which
3893 will require a successful re-installation to clear
3894 up, but it's when <prgn>dpkg</prgn> starts doing
3895 things that are irreversible.
3900 Any files which were in the old version of the package
3901 but not in the new are removed.
3905 The new file list replaces the old.
3909 The new maintainer scripts replace the old.
3913 Any packages all of whose files have been overwritten
3914 during the installation, and which aren't required for
3915 dependencies, are considered to have been removed.
3916 For each such package
3919 <prgn>dpkg</prgn> calls:
3920 <example compact="compact">
3921 <var>disappearer's-postrm</var> disappear \
3922 <var>overwriter</var> <var>overwriter-version</var>
3926 The package's maintainer scripts are removed.
3929 It is noted in the status database as being in a
3930 sane state, namely not installed (any conffiles
3931 it may have are ignored, rather than being
3932 removed by <prgn>dpkg</prgn>). Note that
3933 disappearing packages do not have their prerm
3934 called, because <prgn>dpkg</prgn> doesn't know
3935 in advance that the package is going to
3942 Any files in the package we're unpacking that are also
3943 listed in the file lists of other packages are removed
3944 from those lists. (This will lobotomize the file list
3945 of the "conflicting" package if there is one.)
3949 The backup files made during installation, above, are
3955 The new package's status is now sane, and recorded as
3960 Here is another point of no return - if the
3961 conflicting package's removal fails we do not unwind
3962 the rest of the installation; the conflicting package
3963 is left in a half-removed limbo.
3968 If there was a conflicting package we go and do the
3969 removal actions (described below), starting with the
3970 removal of the conflicting package's files (any that
3971 are also in the package being installed have already
3972 been removed from the conflicting package's file list,
3973 and so do not get removed now).
3979 <sect id="configdetails"><heading>Details of configuration</heading>
3982 When we configure a package (this happens with <tt>dpkg
3983 --install</tt> and <tt>dpkg --configure</tt>), we first
3984 update any <tt>conffile</tt>s and then call:
3985 <example compact="compact">
3986 <var>postinst</var> configure <var>most-recently-configured-version</var>
3991 No attempt is made to unwind after errors during
3992 configuration. If the configuration fails, the package is in
3993 a "Failed Config" state, and an error message is generated.
3997 If there is no most recently configured version
3998 <prgn>dpkg</prgn> will pass a null argument.
4001 Historical note: Truly ancient (pre-1997) versions of
4002 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4003 (including the angle brackets) in this case. Even older
4004 ones did not pass a second argument at all, under any
4005 circumstance. Note that upgrades using such an old dpkg
4006 version are unlikely to work for other reasons, even if
4007 this old argument behavior is handled by your postinst script.
4013 <sect id="removedetails"><heading>Details of removal and/or
4014 configuration purging</heading>
4020 <example compact="compact">
4021 <var>prerm</var> remove
4025 If prerm fails during replacement due to conflict
4027 <var>conflictor's-postinst</var> abort-remove \
4028 in-favour <var>package</var> <var>new-version</var>
4032 <var>postinst</var> abort-remove
4036 If this fails, the package is in a "Failed-Config"
4037 state, or else it remains "Installed".
4041 The package's files are removed (except <tt>conffile</tt>s).
4044 <example compact="compact">
4045 <var>postrm</var> remove
4049 If it fails, there's no error unwind, and the package is in
4050 an "Half-Installed" state.
4055 All the maintainer scripts except the <prgn>postrm</prgn>
4060 If we aren't purging the package we stop here. Note
4061 that packages which have no <prgn>postrm</prgn> and no
4062 <tt>conffile</tt>s are automatically purged when
4063 removed, as there is no difference except for the
4064 <prgn>dpkg</prgn> status.
4068 The <tt>conffile</tt>s and any backup files
4069 (<tt>~</tt>-files, <tt>#*#</tt> files,
4070 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4075 <example compact="compact">
4076 <var>postrm</var> purge
4080 If this fails, the package remains in a "Config-Files"
4085 The package's file list is removed.
4094 <chapt id="relationships">
4095 <heading>Declaring relationships between packages</heading>
4097 <sect id="depsyntax">
4098 <heading>Syntax of relationship fields</heading>
4101 These fields all have a uniform syntax. They are a list of
4102 package names separated by commas.
4106 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4107 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4108 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4109 control file fields of the package, which declare
4110 dependencies on other packages, the package names listed may
4111 also include lists of alternative package names, separated
4112 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4113 if any one of the alternative packages is installed, that
4114 part of the dependency is considered to be satisfied.
4118 All of the fields except for <tt>Provides</tt> may restrict
4119 their applicability to particular versions of each named
4120 package. This is done in parentheses after each individual
4121 package name; the parentheses should contain a relation from
4122 the list below followed by a version number, in the format
4123 described in <ref id="f-Version">.
4127 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4128 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4129 strictly earlier, earlier or equal, exactly equal, later or
4130 equal and strictly later, respectively. The deprecated
4131 forms <tt><</tt> and <tt>></tt> were used to mean
4132 earlier/later or equal, rather than strictly earlier/later,
4133 so they should not appear in new packages (though
4134 <prgn>dpkg</prgn> still supports them).
4138 Whitespace may appear at any point in the version
4139 specification subject to the rules in <ref
4140 id="controlsyntax">, and must appear where it's necessary to
4141 disambiguate; it is not otherwise significant. All of the
4142 relationship fields may span multiple lines. For
4143 consistency and in case of future changes to
4144 <prgn>dpkg</prgn> it is recommended that a single space be
4145 used after a version relationship and before a version
4146 number; it is also conventional to put a single space after
4147 each comma, on either side of each vertical bar, and before
4148 each open parenthesis. When wrapping a relationship field, it
4149 is conventional to do so after a comma and before the space
4150 following that comma.
4154 For example, a list of dependencies might appear as:
4155 <example compact="compact">
4158 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4163 All fields that specify build-time relationships
4164 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4165 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4166 may be restricted to a certain set of architectures. This
4167 is indicated in brackets after each individual package name and
4168 the optional version specification. The brackets enclose a
4169 list of Debian architecture names separated by whitespace.
4170 Exclamation marks may be prepended to each of the names.
4171 (It is not permitted for some names to be prepended with
4172 exclamation marks while others aren't.) If the current Debian
4173 host architecture is not in this list and there are no
4174 exclamation marks in the list, or it is in the list with a
4175 prepended exclamation mark, the package name and the
4176 associated version specification are ignored completely for
4177 the purposes of defining the relationships.
4182 <example compact="compact">
4184 Build-Depends-Indep: texinfo
4185 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4186 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4191 Note that the binary package relationship fields such as
4192 <tt>Depends</tt> appear in one of the binary package
4193 sections of the control file, whereas the build-time
4194 relationships such as <tt>Build-Depends</tt> appear in the
4195 source package section of the control file (which is the
4200 <sect id="binarydeps">
4201 <heading>Binary Dependencies - <tt>Depends</tt>,
4202 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4203 <tt>Pre-Depends</tt>
4207 Packages can declare in their control file that they have
4208 certain relationships to other packages - for example, that
4209 they may not be installed at the same time as certain other
4210 packages, and/or that they depend on the presence of others.
4214 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4215 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4216 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4220 These seven fields are used to declare a dependency
4221 relationship by one package on another. Except for
4222 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4223 depending (binary) package's control file.
4224 (<tt>Enhances</tt> appears in the recommending package's
4225 control file, and <tt>Breaks</tt> appears in the version of
4226 depended-on package which causes the named package to
4231 A <tt>Depends</tt> field takes effect <em>only</em> when a
4232 package is to be configured. It does not prevent a package
4233 being on the system in an unconfigured state while its
4234 dependencies are unsatisfied, and it is possible to replace
4235 a package whose dependencies are satisfied and which is
4236 properly installed with a different version whose
4237 dependencies are not and cannot be satisfied; when this is
4238 done the depending package will be left unconfigured (since
4239 attempts to configure it will give errors) and will not
4240 function properly. If it is necessary, a
4241 <tt>Pre-Depends</tt> field can be used, which has a partial
4242 effect even when a package is being unpacked, as explained
4243 in detail below. (The other three dependency fields,
4244 <tt>Recommends</tt>, <tt>Suggests</tt> and
4245 <tt>Enhances</tt>, are only used by the various front-ends
4246 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4247 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4251 For this reason packages in an installation run are usually
4252 all unpacked first and all configured later; this gives
4253 later versions of packages with dependencies on later
4254 versions of other packages the opportunity to have their
4255 dependencies satisfied.
4259 In case of circular dependencies, since installation or
4260 removal order honoring the dependency order can't be
4261 established, dependency loops are broken at some point
4262 (based on rules below), and some packages may not be able to
4263 rely on their dependencies being present when being
4264 installed or removed, depending on which side of the break
4265 of the circular dependency loop they happen to be on. If one
4266 of the packages in the loop has no postinst script, then the
4267 cycle will be broken at that package, so as to ensure that
4268 all postinst scripts run with the dependencies properly
4269 configured if this is possible. Otherwise the breaking point
4274 The <tt>Depends</tt> field thus allows package maintainers
4275 to impose an order in which packages should be configured.
4279 The meaning of the five dependency fields is as follows:
4281 <tag><tt>Depends</tt></tag>
4284 This declares an absolute dependency. A package will
4285 not be configured unless all of the packages listed in
4286 its <tt>Depends</tt> field have been correctly
4291 The <tt>Depends</tt> field should be used if the
4292 depended-on package is required for the depending
4293 package to provide a significant amount of
4298 The <tt>Depends</tt> field should also be used if the
4299 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4300 <prgn>postrm</prgn> scripts require the package to be
4301 present in order to run. Note, however, that the
4302 <prgn>postrm</prgn> cannot rely on any non-essential
4303 packages to be present during the <tt>purge</tt>
4307 <tag><tt>Recommends</tt></tag>
4310 This declares a strong, but not absolute, dependency.
4314 The <tt>Recommends</tt> field should list packages
4315 that would be found together with this one in all but
4316 unusual installations.
4320 <tag><tt>Suggests</tt></tag>
4322 This is used to declare that one package may be more
4323 useful with one or more others. Using this field
4324 tells the packaging system and the user that the
4325 listed packages are related to this one and can
4326 perhaps enhance its usefulness, but that installing
4327 this one without them is perfectly reasonable.
4330 <tag><tt>Enhances</tt></tag>
4332 This field is similar to Suggests but works in the
4333 opposite direction. It is used to declare that a
4334 package can enhance the functionality of another
4338 <tag><tt>Pre-Depends</tt></tag>
4341 This field is like <tt>Depends</tt>, except that it
4342 also forces <prgn>dpkg</prgn> to complete installation
4343 of the packages named before even starting the
4344 installation of the package which declares the
4345 pre-dependency, as follows:
4349 When a package declaring a pre-dependency is about to
4350 be <em>unpacked</em> the pre-dependency can be
4351 satisfied if the depended-on package is either fully
4352 configured, <em>or even if</em> the depended-on
4353 package(s) are only unpacked or half-configured,
4354 provided that they have been configured correctly at
4355 some point in the past (and not removed or partially
4356 removed since). In this case, both the
4357 previously-configured and currently unpacked or
4358 half-configured versions must satisfy any version
4359 clause in the <tt>Pre-Depends</tt> field.
4363 When the package declaring a pre-dependency is about
4364 to be <em>configured</em>, the pre-dependency will be
4365 treated as a normal <tt>Depends</tt>, that is, it will
4366 be considered satisfied only if the depended-on
4367 package has been correctly configured.
4371 <tt>Pre-Depends</tt> should be used sparingly,
4372 preferably only by packages whose premature upgrade or
4373 installation would hamper the ability of the system to
4374 continue with any upgrade that might be in progress.
4378 <tt>Pre-Depends</tt> are also required if the
4379 <prgn>preinst</prgn> script depends on the named
4380 package. It is best to avoid this situation if
4388 When selecting which level of dependency to use you should
4389 consider how important the depended-on package is to the
4390 functionality of the one declaring the dependency. Some
4391 packages are composed of components of varying degrees of
4392 importance. Such a package should list using
4393 <tt>Depends</tt> the package(s) which are required by the
4394 more important components. The other components'
4395 requirements may be mentioned as Suggestions or
4396 Recommendations, as appropriate to the components' relative
4402 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4405 Using <tt>Breaks</tt> may cause problems for upgrades from older
4406 versions of Debian and should not be used until the stable
4407 release of Debian supports <tt>Breaks</tt>.
4411 When one binary package declares that it breaks another,
4412 <prgn>dpkg</prgn> will refuse to allow the package which
4413 declares <tt>Breaks</tt> be installed unless the broken
4414 package is deconfigured first, and it will refuse to
4415 allow the broken package to be reconfigured.
4419 A package will not be regarded as causing breakage merely
4420 because its configuration files are still installed; it must
4421 be at least half-installed.
4425 A special exception is made for packages which declare that
4426 they break their own package name or a virtual package which
4427 they provide (see below): this does not count as a real
4432 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4433 version clause; such a <tt>Breaks</tt> is introduced in the
4434 version of an (implicit or explicit) dependency which
4435 violates an assumption or reveals a bug in earlier versions
4436 of the broken package. This use of <tt>Breaks</tt> will
4437 inform higher-level package management tools that broken
4438 package must be upgraded before the new one.
4442 If the breaking package also overwrites some files from the
4443 older package, it should use <tt>Replaces</tt> (not
4444 <tt>Conflicts</tt>) to ensure this goes smoothly.
4448 <sect id="conflicts">
4449 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4452 When one binary package declares a conflict with another
4453 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4454 refuse to allow them to be installed on the system at the
4459 If one package is to be installed, the other must be removed
4460 first - if the package being installed is marked as
4461 replacing (see <ref id="replaces">) the one on the system,
4462 or the one on the system is marked as deselected, or both
4463 packages are marked <tt>Essential</tt>, then
4464 <prgn>dpkg</prgn> will automatically remove the package
4465 which is causing the conflict, otherwise it will halt the
4466 installation of the new package with an error. This
4467 mechanism is specifically designed to produce an error when
4468 the installed package is <tt>Essential</tt>, but the new
4473 A package will not cause a conflict merely because its
4474 configuration files are still installed; it must be at least
4479 A special exception is made for packages which declare a
4480 conflict with their own package name, or with a virtual
4481 package which they provide (see below): this does not
4482 prevent their installation, and allows a package to conflict
4483 with others providing a replacement for it. You use this
4484 feature when you want the package in question to be the only
4485 package providing some feature.
4489 A <tt>Conflicts</tt> entry should almost never have an
4490 "earlier than" version clause. This would prevent
4491 <prgn>dpkg</prgn> from upgrading or installing the package
4492 which declared such a conflict until the upgrade or removal
4493 of the conflicted-with package had been completed. Instead,
4494 <tt>Breaks</tt> may be used (once <tt>Breaks</tt> is supported
4495 by the stable release of Debian).
4499 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4503 As well as the names of actual ("concrete") packages, the
4504 package relationship fields <tt>Depends</tt>,
4505 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4506 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4507 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4508 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4509 may mention "virtual packages".
4513 A <em>virtual package</em> is one which appears in the
4514 <tt>Provides</tt> control file field of another package.
4515 The effect is as if the package(s) which provide a
4516 particular virtual package name had been listed by name
4517 everywhere the virtual package name appears. (See also <ref
4522 If there are both concrete and virtual packages of the same
4523 name, then the dependency may be satisfied (or the conflict
4524 caused) by either the concrete package with the name in
4525 question or any other concrete package which provides the
4526 virtual package with the name in question. This is so that,
4527 for example, supposing we have
4528 <example compact="compact">
4531 </example> and someone else releases an enhanced version of
4532 the <tt>bar</tt> package they can say:
4533 <example compact="compact">
4537 and the <tt>bar-plus</tt> package will now also satisfy the
4538 dependency for the <tt>foo</tt> package.
4542 If a relationship field has a version number attached
4543 then only real packages will be considered to see whether
4544 the relationship is satisfied (or the prohibition violated,
4545 for a conflict or breakage) - it is assumed that a real
4546 package which provides the virtual package is not of the
4547 "right" version. So, a <tt>Provides</tt> field may not
4548 contain version numbers, and the version number of the
4549 concrete package which provides a particular virtual package
4550 will not be looked at when considering a dependency on or
4551 conflict with the virtual package name.
4555 It is likely that the ability will be added in a future
4556 release of <prgn>dpkg</prgn> to specify a version number for
4557 each virtual package it provides. This feature is not yet
4558 present, however, and is expected to be used only
4563 If you want to specify which of a set of real packages
4564 should be the default to satisfy a particular dependency on
4565 a virtual package, you should list the real package as an
4566 alternative before the virtual one.
4571 <sect id="replaces"><heading>Overwriting files and replacing
4572 packages - <tt>Replaces</tt></heading>
4575 Packages can declare in their control file that they should
4576 overwrite files in certain other packages, or completely
4577 replace other packages. The <tt>Replaces</tt> control file
4578 field has these two distinct purposes.
4581 <sect1><heading>Overwriting files in other packages</heading>
4584 Firstly, as mentioned before, it is usually an error for a
4585 package to contain files which are on the system in
4590 However, if the overwriting package declares that it
4591 <tt>Replaces</tt> the one containing the file being
4592 overwritten, then <prgn>dpkg</prgn> will replace the file
4593 from the old package with that from the new. The file
4594 will no longer be listed as "owned" by the old package.
4598 If a package is completely replaced in this way, so that
4599 <prgn>dpkg</prgn> does not know of any files it still
4600 contains, it is considered to have "disappeared". It will
4601 be marked as not wanted on the system (selected for
4602 removal) and not installed. Any <tt>conffile</tt>s
4603 details noted for the package will be ignored, as they
4604 will have been taken over by the overwriting package. The
4605 package's <prgn>postrm</prgn> script will be run with a
4606 special argument to allow the package to do any final
4607 cleanup required. See <ref id="mscriptsinstact">.
4610 Replaces is a one way relationship -- you have to
4611 install the replacing package after the replaced
4618 For this usage of <tt>Replaces</tt>, virtual packages (see
4619 <ref id="virtual">) are not considered when looking at a
4620 <tt>Replaces</tt> field - the packages declared as being
4621 replaced must be mentioned by their real names.
4625 Furthermore, this usage of <tt>Replaces</tt> only takes
4626 effect when both packages are at least partially on the
4627 system at once, so that it can only happen if they do not
4628 conflict or if the conflict has been overridden.
4633 <sect1><heading>Replacing whole packages, forcing their
4637 Secondly, <tt>Replaces</tt> allows the packaging system to
4638 resolve which package should be removed when there is a
4639 conflict - see <ref id="conflicts">. This usage only
4640 takes effect when the two packages <em>do</em> conflict,
4641 so that the two usages of this field do not interfere with
4646 In this situation, the package declared as being replaced
4647 can be a virtual package, so for example, all mail
4648 transport agents (MTAs) would have the following fields in
4649 their control files:
4650 <example compact="compact">
4651 Provides: mail-transport-agent
4652 Conflicts: mail-transport-agent
4653 Replaces: mail-transport-agent
4655 ensuring that only one MTA can be installed at any one
4660 <sect id="sourcebinarydeps">
4661 <heading>Relationships between source and binary packages -
4662 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4663 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4667 Source packages that require certain binary packages to be
4668 installed or absent at the time of building the package
4669 can declare relationships to those binary packages.
4673 This is done using the <tt>Build-Depends</tt>,
4674 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4675 <tt>Build-Conflicts-Indep</tt> control file fields.
4679 Build-dependencies on "build-essential" binary packages can be
4680 omitted. Please see <ref id="pkg-relations"> for more information.
4684 The dependencies and conflicts they define must be satisfied
4685 (as defined earlier for binary packages) in order to invoke
4686 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4688 If you make "build-arch" or "binary-arch", you need
4689 Build-Depends. If you make "build-indep" or
4690 "binary-indep", you need Build-Depends and
4691 Build-Depends-Indep. If you make "build" or "binary",
4695 There is no Build-Depends-Arch; this role is essentially
4696 met with Build-Depends. Anyone building the
4697 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4698 is basically assumed to be building the whole package
4699 anyway and so installs all build dependencies. The
4700 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4701 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4702 does not yet know how to check for its existence) and
4703 <tt>binary-arch</tt>.
4706 The purpose of the original split, I recall, was so that
4707 the autobuilders wouldn't need to install extra packages
4708 needed only for the binary-indep targets. But without a
4709 build-arch/build-indep split, this didn't work, since
4710 most of the work is done in the build target, not in the
4716 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4718 The <tt>Build-Depends</tt> and
4719 <tt>Build-Conflicts</tt> fields must be satisfied when
4720 any of the following targets is invoked:
4721 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4722 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4723 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4725 <tag><tt>Build-Depends-Indep</tt>,
4726 <tt>Build-Conflicts-Indep</tt></tag>
4728 The <tt>Build-Depends-Indep</tt> and
4729 <tt>Build-Conflicts-Indep</tt> fields must be
4730 satisfied when any of the following targets is
4731 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4732 <tt>binary</tt> and <tt>binary-indep</tt>.
4742 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4745 Packages containing shared libraries must be constructed with
4746 a little care to make sure that the shared library is always
4747 available. This is especially important for packages whose
4748 shared libraries are vitally important, such as the C library
4749 (currently <tt>libc6</tt>).
4753 Packages involving shared libraries should be split up into
4754 several binary packages. This section mostly deals with how
4755 this separation is to be accomplished; rules for files within
4756 the shared library packages are in <ref id="libraries"> instead.
4759 <sect id="sharedlibs-runtime">
4760 <heading>Run-time shared libraries</heading>
4763 The run-time shared library needs to be placed in a package
4764 whose name changes whenever the shared object version
4767 Since it is common place to install several versions of a
4768 package that just provides shared libraries, it is a
4769 good idea that the library package should not
4770 contain any extraneous non-versioned files, unless they
4771 happen to be in versioned directories.</p>
4773 The most common mechanism is to place it in a package
4775 <package><var>libraryname</var><var>soversion</var></package>,
4776 where <file><var>soversion</var></file> is the version number
4777 in the soname of the shared library<footnote>
4778 The soname is the shared object name: it's the thing
4779 that has to match exactly between building an executable
4780 and running it for the dynamic linker to be able run the
4781 program. For example, if the soname of the library is
4782 <file>libfoo.so.6</file>, the library package would be
4783 called <file>libfoo6</file>.
4785 Alternatively, if it would be confusing to directly append
4786 <var>soversion</var> to <var>libraryname</var> (e.g. because
4787 <var>libraryname</var> itself ends in a number), you may use
4788 <package><var>libraryname</var>-<var>soversion</var></package> and
4789 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4794 If you have several shared libraries built from the same
4795 source tree you may lump them all together into a single
4796 shared library package, provided that you change all of
4797 their sonames at once (so that you don't get filename
4798 clashes if you try to install different versions of the
4799 combined shared libraries package).
4803 The package should install the shared libraries under
4804 their normal names. For example, the <package>libgdbm3</package>
4805 package should install <file>libgdbm.so.3.0.0</file> as
4806 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4807 renamed or re-linked by any <prgn>prerm</prgn> or
4808 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4809 of renaming things safely without affecting running programs,
4810 and attempts to interfere with this are likely to lead to
4815 Shared libraries should not be installed executable, since
4816 the dynamic linker does not require this and trying to
4817 execute a shared library usually results in a core dump.
4821 The run-time library package should include the symbolic link that
4822 <prgn>ldconfig</prgn> would create for the shared libraries.
4823 For example, the <package>libgdbm3</package> package should include
4824 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4825 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4826 linker (for example <prgn>ld.so</prgn> or
4827 <prgn>ld-linux.so.*</prgn>) can find the library between the
4828 time that <prgn>dpkg</prgn> installs it and the time that
4829 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4831 The package management system requires the library to be
4832 placed before the symbolic link pointing to it in the
4833 <file>.deb</file> file. This is so that when
4834 <prgn>dpkg</prgn> comes to install the symlink
4835 (overwriting the previous symlink pointing at an older
4836 version of the library), the new shared library is already
4837 in place. In the past, this was achieved by creating the
4838 library in the temporary packaging directory before
4839 creating the symlink. Unfortunately, this was not always
4840 effective, since the building of the tar file in the
4841 <file>.deb</file> depended on the behavior of the underlying
4842 file system. Some file systems (such as reiserfs) reorder
4843 the files so that the order of creation is forgotten.
4844 Since version 1.7.0, <prgn>dpkg</prgn>
4845 reorders the files itself as necessary when building a
4846 package. Thus it is no longer important to concern
4847 oneself with the order of file creation.
4851 <sect1 id="ldconfig">
4852 <heading><tt>ldconfig</tt></heading>
4855 Any package installing shared libraries in one of the default
4856 library directories of the dynamic linker (which are currently
4857 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4858 listed in <file>/etc/ld.so.conf</file><footnote>
4860 <list compact="compact">
4861 <item>/usr/local/lib</item>
4862 <item>/usr/lib/libc5-compat</item>
4863 <item>/lib/libc5-compat</item>
4866 must use <prgn>ldconfig</prgn> to update the shared library
4871 The package maintainer scripts must only call
4872 <prgn>ldconfig</prgn> under these circumstances:
4873 <list compact="compact">
4874 <item>When the <prgn>postinst</prgn> script is run with a
4875 first argument of <tt>configure</tt>, the script must call
4876 <prgn>ldconfig</prgn>, and may optionally invoke
4877 <prgn>ldconfig</prgn> at other times.
4879 <item>When the <prgn>postrm</prgn> script is run with a
4880 first argument of <tt>remove</tt>, the script should call
4881 <prgn>ldconfig</prgn>.
4886 During install or upgrade, the preinst is called before
4887 the new files are installed, so calling "ldconfig" is
4888 pointless. The preinst of an existing package can also be
4889 called if an upgrade fails. However, this happens during
4890 the critical time when a shared libs may exist on-disk
4891 under a temporary name. Thus, it is dangerous and
4892 forbidden by current policy to call "ldconfig" at this
4897 When a package is installed or upgraded, "postinst
4898 configure" runs after the new files are safely on-disk.
4899 Since it is perfectly safe to invoke ldconfig
4900 unconditionally in a postinst, it is OK for a package to
4901 simply put ldconfig in its postinst without checking the
4902 argument. The postinst can also be called to recover from
4903 a failed upgrade. This happens before any new files are
4904 unpacked, so there is no reason to call "ldconfig" at this
4909 For a package that is being removed, prerm is
4910 called with all the files intact, so calling ldconfig is
4911 useless. The other calls to "prerm" happen in the case of
4912 upgrade at a time when all the files of the old package
4913 are on-disk, so again calling "ldconfig" is pointless.
4917 postrm, on the other hand, is called with the "remove"
4918 argument just after the files are removed, so this is
4919 the proper time to call "ldconfig" to notify the system
4920 of the fact that the shared libraries from the package
4921 are removed. The postrm can be called at several other
4922 times. At the time of "postrm purge", "postrm
4923 abort-install", or "postrm abort-upgrade", calling
4924 "ldconfig" is useless because the shared lib files are
4925 not on-disk. However, when "postrm" is invoked with
4926 arguments "upgrade", "failed-upgrade", or "disappear", a
4927 shared lib may exist on-disk under a temporary filename.
4935 <sect id="sharedlibs-support-files">
4936 <heading>Shared library support files</heading>
4939 If your package contains files whose names do not change with
4940 each change in the library shared object version, you must not
4941 put them in the shared library package. Otherwise, several
4942 versions of the shared library cannot be installed at the same
4943 time without filename clashes, making upgrades and transitions
4944 unnecessarily difficult.
4948 It is recommended that supporting files and run-time support
4949 programs that do not need to be invoked manually by users, but
4950 are nevertheless required for the package to function, be placed
4951 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
4952 preferably under <file>/usr/lib/</file><var>package-name</var>.
4953 If the program or file is architecture independent, the
4954 recommendation is for it to be placed in a subdirectory of
4955 <file>/usr/share</file> instead, preferably under
4956 <file>/usr/share/</file><var>package-name</var>. Following the
4957 <var>package-name</var> naming convention ensures that the file
4958 names change when the shared object version changes.
4962 Run-time support programs that use the shared library but are
4963 not required for the library to function or files used by the
4964 shared library that can be used by any version of the shared
4965 library package should instead be put in a separate package.
4966 This package might typically be named
4967 <package><var>libraryname</var>-tools</package>; note the
4968 absence of the <var>soversion</var> in the package name.
4972 Files and support programs only useful when compiling software
4973 against the library should be included in the development
4974 package for the library.<footnote>
4975 For example, a <file><var>package-name</var>-config</file>
4976 script or <package>pkg-config</package> configuration files.
4981 <sect id="sharedlibs-static">
4982 <heading>Static libraries</heading>
4985 The static library (<file><var>libraryname.a</var></file>)
4986 is usually provided in addition to the shared version.
4987 It is placed into the development package (see below).
4991 In some cases, it is acceptable for a library to be
4992 available in static form only; these cases include:
4994 <item>libraries for languages whose shared library support
4995 is immature or unstable</item>
4996 <item>libraries whose interfaces are in flux or under
4997 development (commonly the case when the library's
4998 major version number is zero, or where the ABI breaks
4999 across patchlevels)</item>
5000 <item>libraries which are explicitly intended to be
5001 available only in static form by their upstream
5006 <sect id="sharedlibs-dev">
5007 <heading>Development files</heading>
5010 The development files associated to a shared library need to be
5011 placed in a package called
5012 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5013 or if you prefer only to support one development version at a
5014 time, <package><var>libraryname</var>-dev</package>.
5018 In case several development versions of a library exist, you may
5019 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5020 <ref id="conflicts">) to ensure that the user only installs one
5021 development version at a time (as different development versions are
5022 likely to have the same header files in them, which would cause a
5023 filename clash if both were installed).
5027 The development package should contain a symlink for the associated
5028 shared library without a version number. For example, the
5029 <package>libgdbm-dev</package> package should include a symlink
5030 from <file>/usr/lib/libgdbm.so</file> to
5031 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5032 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5033 <file>libgdbm.so</file> when compiling dynamically.
5037 <sect id="sharedlibs-intradeps">
5038 <heading>Dependencies between the packages of the same library</heading>
5041 Typically the development version should have an exact
5042 version dependency on the runtime library, to make sure that
5043 compilation and linking happens correctly. The
5044 <tt>${binary:Version}</tt> substitution variable can be
5045 useful for this purpose.
5047 Previously, <tt>${Source-Version}</tt> was used, but its name
5048 was confusing and it has been deprecated since dpkg 1.13.19.
5053 <sect id="sharedlibs-shlibdeps">
5054 <heading>Dependencies between the library and other packages -
5055 the <tt>shlibs</tt> system</heading>
5058 If a package contains a binary or library which links to a
5059 shared library, we must ensure that when the package is
5060 installed on the system, all of the libraries needed are
5061 also installed. This requirement led to the creation of the
5062 <tt>shlibs</tt> system, which is very simple in its design:
5063 any package which <em>provides</em> a shared library also
5064 provides information on the package dependencies required to
5065 ensure the presence of this library, and any package which
5066 <em>uses</em> a shared library uses this information to
5067 determine the dependencies it requires. The files which
5068 contain the mapping from shared libraries to the necessary
5069 dependency information are called <file>shlibs</file> files.
5073 Thus, when a package is built which contains any shared
5074 libraries, it must provide a <file>shlibs</file> file for other
5075 packages to use, and when a package is built which contains
5076 any shared libraries or compiled binaries, it must run
5077 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5078 on these to determine the libraries used and hence the
5079 dependencies needed by this package.<footnote>
5081 In the past, the shared libraries linked to were
5082 determined by calling <prgn>ldd</prgn>, but now
5083 <prgn>objdump</prgn> is used to do this. The only
5084 change this makes to package building is that
5085 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5086 libraries, whereas in the past this was unnecessary.
5087 The rest of this footnote explains the advantage that
5092 We say that a binary <tt>foo</tt> <em>directly</em> uses
5093 a library <tt>libbar</tt> if it is explicitly linked
5094 with that library (that is, it uses the flag
5095 <tt>-lbar</tt> during the linking stage). Other
5096 libraries that are needed by <tt>libbar</tt> are linked
5097 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5098 linker will load them automatically when it loads
5099 <tt>libbar</tt>. A package should depend on
5100 the libraries it directly uses, and the dependencies for
5101 those libraries should automatically pull in the other
5106 Unfortunately, the <prgn>ldd</prgn> program shows both
5107 the directly and indirectly used libraries, meaning that
5108 the dependencies determined included both direct and
5109 indirect dependencies. The use of <prgn>objdump</prgn>
5110 avoids this problem by determining only the directly
5115 A good example of where this helps is the following. We
5116 could update <tt>libimlib</tt> with a new version that
5117 supports a new graphics format called dgf (but retaining
5118 the same major version number). If we used the old
5119 <prgn>ldd</prgn> method, every package that uses
5120 <tt>libimlib</tt> would need to be recompiled so it
5121 would also depend on <tt>libdgf</tt> or it wouldn't run
5122 due to missing symbols. However with the new system,
5123 packages using <tt>libimlib</tt> can rely on
5124 <tt>libimlib</tt> itself having the dependency on
5125 <tt>libdgf</tt> and so they would not need rebuilding.
5131 In the following sections, we will first describe where the
5132 various <tt>shlibs</tt> files are to be found, then how to
5133 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5134 file format and how to create them if your package contains a
5139 <heading>The <tt>shlibs</tt> files present on the system</heading>
5142 There are several places where <tt>shlibs</tt> files are
5143 found. The following list gives them in the order in which
5145 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5146 (The first one which gives the required information is used.)
5152 <p><file>debian/shlibs.local</file></p>
5155 This lists overrides for this package. Its use is
5156 described below (see <ref id="shlibslocal">).
5161 <p><file>/etc/dpkg/shlibs.override</file></p>
5164 This lists global overrides. This list is normally
5165 empty. It is maintained by the local system
5171 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5174 When packages are being built, any
5175 <file>debian/shlibs</file> files are copied into the
5176 control file area of the temporary build directory and
5177 given the name <file>shlibs</file>. These files give
5178 details of any shared libraries included in the
5180 An example may help here. Let us say that the
5181 source package <tt>foo</tt> generates two binary
5182 packages, <tt>libfoo2</tt> and
5183 <tt>foo-runtime</tt>. When building the binary
5184 packages, the two packages are created in the
5185 directories <file>debian/libfoo2</file> and
5186 <file>debian/foo-runtime</file> respectively.
5187 (<file>debian/tmp</file> could be used instead of one
5188 of these.) Since <tt>libfoo2</tt> provides the
5189 <tt>libfoo</tt> shared library, it will require a
5190 <tt>shlibs</tt> file, which will be installed in
5191 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5193 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5194 when <prgn>dpkg-shlibdeps</prgn> is run on the
5196 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5198 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5199 determine whether <tt>foo-prog</tt>'s library
5200 dependencies are satisfied by any of the libraries
5201 provided by <tt>libfoo2</tt>. For this reason,
5202 <prgn>dpkg-shlibdeps</prgn> must only be run once
5203 all of the individual binary packages'
5204 <tt>shlibs</tt> files have been installed into the
5211 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5214 These are the <file>shlibs</file> files corresponding to
5215 all of the packages installed on the system, and are
5216 maintained by the relevant package maintainers.
5221 <p><file>/etc/dpkg/shlibs.default</file></p>
5224 This file lists any shared libraries whose packages
5225 have failed to provide correct <file>shlibs</file> files.
5226 It was used when the <file>shlibs</file> setup was first
5227 introduced, but it is now normally empty. It is
5228 maintained by the <tt>dpkg</tt> maintainer.
5236 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5237 <file>shlibs</file> files</heading>
5241 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5242 into your <file>debian/rules</file> file. If your package
5243 contains only compiled binaries and libraries (but no scripts),
5244 you can use a command such as:
5245 <example compact="compact">
5246 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5247 debian/tmp/usr/lib/*
5249 Otherwise, you will need to explicitly list the compiled
5250 binaries and libraries.<footnote>
5251 If you are using <tt>debhelper</tt>, the
5252 <prgn>dh_shlibdeps</prgn> program will do this work for
5253 you. It will also correctly handle multi-binary
5259 This command puts the dependency information into the
5260 <file>debian/substvars</file> file, which is then used by
5261 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5262 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5263 field in the control file for this to work.
5267 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5268 done. If it does complain you might need to create your own
5269 <file>debian/shlibs.local</file> file, as explained below (see
5270 <ref id="shlibslocal">).
5274 If you have multiple binary packages, you will need to call
5275 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5276 compiled libraries or binaries. In such a case, you will
5277 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5278 utilities to specify a different <file>substvars</file> file.
5282 If you are creating a udeb for use in the Debian Installer, you
5283 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5284 the dependency line of type <tt>udeb</tt> by adding
5285 <tt>-tudeb</tt> as option<footnote>
5286 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5287 will automatically add this option if it knows it is
5289 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5290 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5291 fall back to the regular dependency line.
5295 For more details on dpkg-shlibdeps, please see
5296 <ref id="pkg-dpkg-shlibdeps"> and
5297 <manref name="dpkg-shlibdeps" section="1">.
5302 <heading>The <file>shlibs</file> File Format</heading>
5305 Each <file>shlibs</file> file has the same format. Lines
5306 beginning with <tt>#</tt> are considered to be comments and
5307 are ignored. Each line is of the form:
5308 <example compact="compact">
5309 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5314 We will explain this by reference to the example of the
5315 <tt>zlib1g</tt> package, which (at the time of writing)
5316 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5320 <var>type</var> is an optional element that indicates the type
5321 of package for which the line is valid. The only type currently
5322 in use is <tt>udeb</tt>. The colon and space after the type are
5327 <var>library-name</var> is the name of the shared library,
5328 in this case <tt>libz</tt>. (This must match the name part
5329 of the soname, see below.)
5333 <var>soname-version</var> is the version part of the soname of
5334 the library. The soname is the thing that must exactly match
5335 for the library to be recognized by the dynamic linker, and is
5337 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5338 example, <tt>libz.so.1</tt>.<footnote>
5339 This can be determined using the command
5340 <example compact="compact">
5341 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5344 The version part is the part which comes after
5345 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5349 <var>dependencies</var> has the same syntax as a dependency
5350 field in a binary package control file. It should give
5351 details of which packages are required to satisfy a binary
5352 built against the version of the library contained in the
5353 package. See <ref id="depsyntax"> for details.
5357 In our example, if the first version of the <tt>zlib1g</tt>
5358 package which contained a minor number of at least
5359 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5360 <tt>shlibs</tt> entry for this library could say:
5361 <example compact="compact">
5362 libz 1 zlib1g (>= 1:1.1.3)
5364 The version-specific dependency is to avoid warnings from
5365 the dynamic linker about using older shared libraries with
5370 As zlib1g also provides a udeb containing the shared library,
5371 there would also be a second line:
5372 <example compact="compact">
5373 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5379 <heading>Providing a <file>shlibs</file> file</heading>
5382 If your package provides a shared library, you need to create
5383 a <file>shlibs</file> file following the format described above.
5384 It is usual to call this file <file>debian/shlibs</file> (but if
5385 you have multiple binary packages, you might want to call it
5386 <file>debian/shlibs.<var>package</var></file> instead). Then
5387 let <file>debian/rules</file> install it in the control area:
5388 <example compact="compact">
5389 install -m644 debian/shlibs debian/tmp/DEBIAN
5391 or, in the case of a multi-binary package:
5392 <example compact="compact">
5393 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5395 An alternative way of doing this is to create the
5396 <file>shlibs</file> file in the control area directly from
5397 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5398 file at all,<footnote>
5399 This is what <prgn>dh_makeshlibs</prgn> in the
5400 <tt>debhelper</tt> suite does. If your package also has a udeb
5401 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5402 automatically generate the <tt>udeb:</tt> lines if you specify
5403 the name of the udeb with the <tt>--add-udeb</tt> option.
5405 since the <file>debian/shlibs</file> file itself is ignored by
5406 <prgn>dpkg-shlibdeps</prgn>.
5410 As <prgn>dpkg-shlibdeps</prgn> reads the
5411 <file>DEBIAN/shlibs</file> files in all of the binary packages
5412 being built from this source package, all of the
5413 <file>DEBIAN/shlibs</file> files should be installed before
5414 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5419 <sect1 id="shlibslocal">
5420 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5423 This file is intended only as a <em>temporary</em> fix if
5424 your binaries or libraries depend on a library whose package
5425 does not yet provide a correct <file>shlibs</file> file.
5429 We will assume that you are trying to package a binary
5430 <tt>foo</tt>. When you try running
5431 <prgn>dpkg-shlibdeps</prgn> you get the following error
5432 message (<tt>-O</tt> displays the dependency information on
5433 <tt>stdout</tt> instead of writing it to
5434 <tt>debian/substvars</tt>, and the lines have been wrapped
5435 for ease of reading):
5436 <example compact="compact">
5437 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5438 dpkg-shlibdeps: warning: unable to find dependency
5439 information for shared library libbar (soname 1,
5440 path /usr/lib/libbar.so.1, dependency field Depends)
5441 shlibs:Depends=libc6 (>= 2.2.2-2)
5443 You can then run <prgn>ldd</prgn> on the binary to find the
5444 full location of the library concerned:
5445 <example compact="compact">
5447 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5448 libc.so.6 => /lib/libc.so.6 (0x40032000)
5449 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5451 So the <prgn>foo</prgn> binary depends on the
5452 <prgn>libbar</prgn> shared library, but no package seems to
5453 provide a <file>*.shlibs</file> file handling
5454 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5455 determine the package responsible:
5456 <example compact="compact">
5457 $ dpkg -S /usr/lib/libbar.so.1
5458 bar1: /usr/lib/libbar.so.1
5459 $ dpkg -s bar1 | grep Version
5462 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5463 is the one we are using. Now we can file a bug against the
5464 <tt>bar1</tt> package and create our own
5465 <file>debian/shlibs.local</file> to locally fix the problem.
5466 Including the following line into your
5467 <file>debian/shlibs.local</file> file:
5468 <example compact="compact">
5469 libbar 1 bar1 (>= 1.0-1)
5471 should allow the package build to work.
5475 As soon as the maintainer of <tt>bar1</tt> provides a
5476 correct <file>shlibs</file> file, you should remove this line
5477 from your <file>debian/shlibs.local</file> file. (You should
5478 probably also then have a versioned <tt>Build-Depends</tt>
5479 on <tt>bar1</tt> to help ensure that others do not have the
5480 same problem building your package.)
5489 <chapt id="opersys"><heading>The Operating System</heading>
5492 <heading>File system hierarchy</heading>
5496 <heading>File system Structure</heading>
5499 The location of all installed files and directories must
5500 comply with the File system Hierarchy Standard (FHS),
5501 version 2.3, with the exceptions noted below, and except
5502 where doing so would violate other terms of Debian
5503 Policy. The following exceptions to the FHS apply:
5508 Legacy XFree86 servers are permitted to retain the
5509 configuration file location
5510 <file>/etc/X11/XF86Config-4</file>.
5515 The optional rules related to user specific
5516 configuration files for applications are stored in
5517 the user's home directory are relaxed. It is
5518 recommended that such files start with the
5519 '<tt>.</tt>' character (a "dot file"), and if an
5520 application needs to create more than one dot file
5521 then the preferred placement is in a subdirectory
5522 with a name starting with a '.' character, (a "dot
5523 directory"). In this case it is recommended the
5524 configuration files not start with the '.'
5530 The requirement for amd64 to use <file>/lib64</file>
5531 for 64 bit binaries is removed.
5536 The requirement that
5537 <file>/usr/local/share/man</file> be "synonymous"
5538 with <file>/usr/local/man</file> is relaxed to a
5543 The requirement that windowmanagers with a single
5544 configuration file call it <file>system.*wmrc</file>
5545 is removed, as is the restriction that the window
5546 manager subdirectory be named identically to the
5547 window manager name itself.
5552 The requirement that boot manager configuration
5553 files live in <file>/etc</file>, or at least are
5554 symlinked there, is relaxed to a recommendation.
5561 The version of this document referred here can be
5562 found in the <tt>debian-policy</tt> package or on <url
5563 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5564 name="FHS (Debian copy)"> alongside this manual (or, if
5565 you have the <package>debian-policy</package> installed,
5567 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5568 (local copy)">). The
5569 latest version, which may be a more recent version, may
5571 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5572 Specific questions about following the standard may be
5573 asked on the <tt>debian-devel</tt> mailing list, or
5574 referred to the FHS mailing list (see the
5575 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5581 <heading>Site-specific programs</heading>
5584 As mandated by the FHS, packages must not place any
5585 files in <file>/usr/local</file>, either by putting them in
5586 the file system archive to be unpacked by <prgn>dpkg</prgn>
5587 or by manipulating them in their maintainer scripts.
5591 However, the package may create empty directories below
5592 <file>/usr/local</file> so that the system administrator knows
5593 where to place site-specific files. These are not
5594 directories <em>in</em> <file>/usr/local</file>, but are
5595 children of directories in <file>/usr/local</file>. These
5596 directories (<file>/usr/local/*/dir/</file>)
5597 should be removed on package removal if they are
5602 Note, that this applies only to directories <em>below</em>
5603 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5604 Packages must not create sub-directories in the directory
5605 <file>/usr/local</file> itself, except those listed in FHS,
5606 section 4.5. However, you may create directories below
5607 them as you wish. You must not remove any of the
5608 directories listed in 4.5, even if you created them.
5612 Since <file>/usr/local</file> can be mounted read-only from a
5613 remote server, these directories must be created and
5614 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5615 maintainer scripts and not be included in the
5616 <file>.deb</file> archive. These scripts must not fail if
5617 either of these operations fail.
5621 For example, the <tt>emacsen-common</tt> package could
5622 contain something like
5623 <example compact="compact">
5624 if [ ! -e /usr/local/share/emacs ]
5626 if mkdir /usr/local/share/emacs 2>/dev/null
5628 chown root:staff /usr/local/share/emacs
5629 chmod 2775 /usr/local/share/emacs
5633 in its <prgn>postinst</prgn> script, and
5634 <example compact="compact">
5635 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5636 rmdir /usr/local/share/emacs 2>/dev/null || true
5638 in the <prgn>prerm</prgn> script. (Note that this form is
5639 used to ensure that if the script is interrupted, the
5640 directory <file>/usr/local/share/emacs</file> will still be
5645 If you do create a directory in <file>/usr/local</file> for
5646 local additions to a package, you should ensure that
5647 settings in <file>/usr/local</file> take precedence over the
5648 equivalents in <file>/usr</file>.
5652 However, because <file>/usr/local</file> and its contents are
5653 for exclusive use of the local administrator, a package
5654 must not rely on the presence or absence of files or
5655 directories in <file>/usr/local</file> for normal operation.
5659 The <file>/usr/local</file> directory itself and all the
5660 subdirectories created by the package should (by default) have
5661 permissions 2775 (group-writable and set-group-id) and be
5662 owned by <tt>root:staff</tt>.
5667 <heading>The system-wide mail directory</heading>
5669 The system-wide mail directory is <file>/var/mail</file>. This
5670 directory is part of the base system and should not owned
5671 by any particular mail agents. The use of the old
5672 location <file>/var/spool/mail</file> is deprecated, even
5673 though the spool may still be physically located there.
5674 To maintain partial upgrade compatibility for systems
5675 which have <file>/var/spool/mail</file> as their physical mail
5676 spool, packages using <file>/var/mail</file> must depend on
5677 either <package>libc6</package> (>= 2.1.3-13), or on
5678 <package>base-files</package> (>= 2.2.0), or on later
5679 versions of either one of these packages.
5685 <heading>Users and groups</heading>
5688 <heading>Introduction</heading>
5690 The Debian system can be configured to use either plain or
5695 Some user ids (UIDs) and group ids (GIDs) are reserved
5696 globally for use by certain packages. Because some
5697 packages need to include files which are owned by these
5698 users or groups, or need the ids compiled into binaries,
5699 these ids must be used on any Debian system only for the
5700 purpose for which they are allocated. This is a serious
5701 restriction, and we should avoid getting in the way of
5702 local administration policies. In particular, many sites
5703 allocate users and/or local system groups starting at 100.
5707 Apart from this we should have dynamically allocated ids,
5708 which should by default be arranged in some sensible
5709 order, but the behavior should be configurable.
5713 Packages other than <tt>base-passwd</tt> must not modify
5714 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5715 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5720 <heading>UID and GID classes</heading>
5722 The UID and GID numbers are divided into classes as
5728 Globally allocated by the Debian project, the same
5729 on every Debian system. These ids will appear in
5730 the <file>passwd</file> and <file>group</file> files of all
5731 Debian systems, new ids in this range being added
5732 automatically as the <tt>base-passwd</tt> package is
5737 Packages which need a single statically allocated
5738 uid or gid should use one of these; their
5739 maintainers should ask the <tt>base-passwd</tt>
5747 Dynamically allocated system users and groups.
5748 Packages which need a user or group, but can have
5749 this user or group allocated dynamically and
5750 differently on each system, should use <tt>adduser
5751 --system</tt> to create the group and/or user.
5752 <prgn>adduser</prgn> will check for the existence of
5753 the user or group, and if necessary choose an unused
5754 id based on the ranges specified in
5755 <file>adduser.conf</file>.
5759 <tag>1000-29999:</tag>
5762 Dynamically allocated user accounts. By default
5763 <prgn>adduser</prgn> will choose UIDs and GIDs for
5764 user accounts in this range, though
5765 <file>adduser.conf</file> may be used to modify this
5770 <tag>30000-59999:</tag>
5775 <tag>60000-64999:</tag>
5778 Globally allocated by the Debian project, but only
5779 created on demand. The ids are allocated centrally
5780 and statically, but the actual accounts are only
5781 created on users' systems on demand.
5785 These ids are for packages which are obscure or
5786 which require many statically-allocated ids. These
5787 packages should check for and create the accounts in
5788 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5789 <prgn>adduser</prgn> if it has this facility) if
5790 necessary. Packages which are likely to require
5791 further allocations should have a "hole" left after
5792 them in the allocation, to give them room to
5797 <tag>65000-65533:</tag>
5805 User <tt>nobody</tt>. The corresponding gid refers
5806 to the group <tt>nogroup</tt>.
5813 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5814 not</em> be used, because it is the error return
5823 <sect id="sysvinit">
5824 <heading>System run levels and <file>init.d</file> scripts</heading>
5826 <sect1 id="/etc/init.d">
5827 <heading>Introduction</heading>
5830 The <file>/etc/init.d</file> directory contains the scripts
5831 executed by <prgn>init</prgn> at boot time and when the
5832 init state (or "runlevel") is changed (see <manref
5833 name="init" section="8">).
5837 There are at least two different, yet functionally
5838 equivalent, ways of handling these scripts. For the sake
5839 of simplicity, this document describes only the symbolic
5840 link method. However, it must not be assumed by maintainer
5841 scripts that this method is being used, and any automated
5842 manipulation of the various runlevel behaviors by
5843 maintainer scripts must be performed using
5844 <prgn>update-rc.d</prgn> as described below and not by
5845 manually installing or removing symlinks. For information
5846 on the implementation details of the other method,
5847 implemented in the <tt>file-rc</tt> package, please refer
5848 to the documentation of that package.
5852 These scripts are referenced by symbolic links in the
5853 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5854 runlevels, <prgn>init</prgn> looks in the directory
5855 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5856 execute, where <tt><var>n</var></tt> is the runlevel that
5857 is being changed to, or <tt>S</tt> for the boot-up
5862 The names of the links all have the form
5863 <file>S<var>mm</var><var>script</var></file> or
5864 <file>K<var>mm</var><var>script</var></file> where
5865 <var>mm</var> is a two-digit number and <var>script</var>
5866 is the name of the script (this should be the same as the
5867 name of the actual script in <file>/etc/init.d</file>).
5871 When <prgn>init</prgn> changes runlevel first the targets
5872 of the links whose names start with a <tt>K</tt> are
5873 executed, each with the single argument <tt>stop</tt>,
5874 followed by the scripts prefixed with an <tt>S</tt>, each
5875 with the single argument <tt>start</tt>. (The links are
5876 those in the <file>/etc/rc<var>n</var>.d</file> directory
5877 corresponding to the new runlevel.) The <tt>K</tt> links
5878 are responsible for killing services and the <tt>S</tt>
5879 link for starting services upon entering the runlevel.
5883 For example, if we are changing from runlevel 2 to
5884 runlevel 3, init will first execute all of the <tt>K</tt>
5885 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5886 all of the <tt>S</tt> prefixed scripts in that directory.
5887 The links starting with <tt>K</tt> will cause the
5888 referred-to file to be executed with an argument of
5889 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5894 The two-digit number <var>mm</var> is used to determine
5895 the order in which to run the scripts: low-numbered links
5896 have their scripts run first. For example, the
5897 <tt>K20</tt> scripts will be executed before the
5898 <tt>K30</tt> scripts. This is used when a certain service
5899 must be started before another. For example, the name
5900 server <prgn>bind</prgn> might need to be started before
5901 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5902 can set up its access lists. In this case, the script
5903 that starts <prgn>bind</prgn> would have a lower number
5904 than the script that starts <prgn>inn</prgn> so that it
5906 <example compact="compact">
5913 The two runlevels 0 (halt) and 6 (reboot) are slightly
5914 different. In these runlevels, the links with an
5915 <tt>S</tt> prefix are still called after those with a
5916 <tt>K</tt> prefix, but they too are called with the single
5917 argument <tt>stop</tt>.
5921 Also, if the script name ends in <tt>.sh</tt>, the script
5922 will be sourced in runlevel <tt>S</tt> rather than being
5923 run in a forked subprocess, but will be explicitly run by
5924 <prgn>sh</prgn> in all other runlevels.
5929 <heading>Writing the scripts</heading>
5932 Packages that include daemons for system services should
5933 place scripts in <file>/etc/init.d</file> to start or stop
5934 services at boot time or during a change of runlevel.
5935 These scripts should be named
5936 <file>/etc/init.d/<var>package</var></file>, and they should
5937 accept one argument, saying what to do:
5940 <tag><tt>start</tt></tag>
5941 <item>start the service,</item>
5943 <tag><tt>stop</tt></tag>
5944 <item>stop the service,</item>
5946 <tag><tt>restart</tt></tag>
5947 <item>stop and restart the service if it's already running,
5948 otherwise start the service</item>
5950 <tag><tt>reload</tt></tag>
5951 <item><p>cause the configuration of the service to be
5952 reloaded without actually stopping and restarting
5955 <tag><tt>force-reload</tt></tag>
5956 <item>cause the configuration to be reloaded if the
5957 service supports this, otherwise restart the
5961 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5962 <tt>force-reload</tt> options should be supported by all
5963 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5968 The <file>init.d</file> scripts must ensure that they will
5969 behave sensibly (i.e., returning success and not starting
5970 multiple copies of a service) if invoked with <tt>start</tt>
5971 when the service is already running, or with <tt>stop</tt>
5972 when it isn't, and that they don't kill unfortunately-named
5973 user processes. The best way to achieve this is usually to
5974 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
5979 If a service reloads its configuration automatically (as
5980 in the case of <prgn>cron</prgn>, for example), the
5981 <tt>reload</tt> option of the <file>init.d</file> script
5982 should behave as if the configuration has been reloaded
5987 The <file>/etc/init.d</file> scripts must be treated as
5988 configuration files, either (if they are present in the
5989 package, that is, in the .deb file) by marking them as
5990 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5991 by managing them correctly in the maintainer scripts (see
5992 <ref id="config-files">). This is important since we want
5993 to give the local system administrator the chance to adapt
5994 the scripts to the local system, e.g., to disable a
5995 service without de-installing the package, or to specify
5996 some special command line options when starting a service,
5997 while making sure their changes aren't lost during the next
6002 These scripts should not fail obscurely when the
6003 configuration files remain but the package has been
6004 removed, as configuration files remain on the system after
6005 the package has been removed. Only when <prgn>dpkg</prgn>
6006 is executed with the <tt>--purge</tt> option will
6007 configuration files be removed. In particular, as the
6008 <file>/etc/init.d/<var>package</var></file> script itself is
6009 usually a <tt>conffile</tt>, it will remain on the system
6010 if the package is removed but not purged. Therefore, you
6011 should include a <tt>test</tt> statement at the top of the
6013 <example compact="compact">
6014 test -f <var>program-executed-later-in-script</var> || exit 0
6019 Often there are some variables in the <file>init.d</file>
6020 scripts whose values control the behavior of the scripts,
6021 and which a system administrator is likely to want to
6022 change. As the scripts themselves are frequently
6023 <tt>conffile</tt>s, modifying them requires that the
6024 administrator merge in their changes each time the package
6025 is upgraded and the <tt>conffile</tt> changes. To ease
6026 the burden on the system administrator, such configurable
6027 values should not be placed directly in the script.
6028 Instead, they should be placed in a file in
6029 <file>/etc/default</file>, which typically will have the same
6030 base name as the <file>init.d</file> script. This extra file
6031 should be sourced by the script when the script runs. It
6032 must contain only variable settings and comments in SUSv3
6033 <prgn>sh</prgn> format. It may either be a
6034 <tt>conffile</tt> or a configuration file maintained by
6035 the package maintainer scripts. See <ref id="config-files">
6040 To ensure that vital configurable values are always
6041 available, the <file>init.d</file> script should set default
6042 values for each of the shell variables it uses, either
6043 before sourcing the <file>/etc/default/</file> file or
6044 afterwards using something like the <tt>:
6045 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6046 script must behave sensibly and not fail if the
6047 <file>/etc/default</file> file is deleted.
6052 <heading>Interfacing with the initscript system</heading>
6055 Maintainers should use the abstraction layer provided by
6056 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6057 programs to deal with initscripts in their packages'
6058 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6059 and <prgn>postrm</prgn>.
6063 Directly managing the /etc/rc?.d links and directly
6064 invoking the <file>/etc/init.d/</file> initscripts should
6065 be done only by packages providing the initscript
6066 subsystem (such as <prgn>sysv-rc</prgn> and
6067 <prgn>file-rc</prgn>).
6071 <heading>Managing the links</heading>
6074 The program <prgn>update-rc.d</prgn> is provided for
6075 package maintainers to arrange for the proper creation and
6076 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6077 or their functional equivalent if another method is being
6078 used. This may be used by maintainers in their packages'
6079 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6083 You must not include any <file>/etc/rc<var>n</var>.d</file>
6084 symbolic links in the actual archive or manually create or
6085 remove the symbolic links in maintainer scripts; you must
6086 use the <prgn>update-rc.d</prgn> program instead. (The
6087 former will fail if an alternative method of maintaining
6088 runlevel information is being used.) You must not include
6089 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6090 in the archive either. (Only the <tt>sysvinit</tt>
6095 By default <prgn>update-rc.d</prgn> will start services in
6096 each of the multi-user state runlevels (2, 3, 4, and 5)
6097 and stop them in the halt runlevel (0), the single-user
6098 runlevel (1) and the reboot runlevel (6). The system
6099 administrator will have the opportunity to customize
6100 runlevels by simply adding, moving, or removing the
6101 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6102 symbolic links are being used, or by modifying
6103 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6108 To get the default behavior for your package, put in your
6109 <prgn>postinst</prgn> script
6110 <example compact="compact">
6111 update-rc.d <var>package</var> defaults
6113 and in your <prgn>postrm</prgn>
6114 <example compact="compact">
6115 if [ "$1" = purge ]; then
6116 update-rc.d <var>package</var> remove
6118 </example>. Note that if your package changes runlevels
6119 or priority, you may have to remove and recreate the links,
6120 since otherwise the old links may persist. Refer to the
6121 documentation of <prgn>update-rc.d</prgn>.
6125 This will use a default sequence number of 20. If it does
6126 not matter when or in which order the <file>init.d</file>
6127 script is run, use this default. If it does, then you
6128 should talk to the maintainer of the <prgn>sysvinit</prgn>
6129 package or post to <tt>debian-devel</tt>, and they will
6130 help you choose a number.
6134 For more information about using <tt>update-rc.d</tt>,
6135 please consult its man page <manref name="update-rc.d"
6141 <heading>Running initscripts</heading>
6143 The program <prgn>invoke-rc.d</prgn> is provided to make
6144 it easier for package maintainers to properly invoke an
6145 initscript, obeying runlevel and other locally-defined
6146 constraints that might limit a package's right to start,
6147 stop and otherwise manage services. This program may be
6148 used by maintainers in their packages' scripts.
6152 The package maintainer scripts must use
6153 <prgn>invoke-rc.d</prgn> to invoke the
6154 <file>/etc/init.d/*</file> initscripts, instead of
6155 calling them directly.
6159 By default, <prgn>invoke-rc.d</prgn> will pass any
6160 action requests (start, stop, reload, restart...) to the
6161 <file>/etc/init.d</file> script, filtering out requests
6162 to start or restart a service out of its intended
6167 Most packages will simply need to change:
6168 <example compact="compact">/etc/init.d/<package>
6169 <action></example> in their <prgn>postinst</prgn>
6170 and <prgn>prerm</prgn> scripts to:
6171 <example compact="compact">
6172 if which invoke-rc.d >/dev/null 2>&1; then
6173 invoke-rc.d <var>package</var> <action>
6175 /etc/init.d/<var>package</var> <action>
6181 A package should register its initscript services using
6182 <prgn>update-rc.d</prgn> before it tries to invoke them
6183 using <prgn>invoke-rc.d</prgn>. Invocation of
6184 unregistered services may fail.
6188 For more information about using
6189 <prgn>invoke-rc.d</prgn>, please consult its man page
6190 <manref name="invoke-rc.d" section="8">.
6196 <heading>Boot-time initialization</heading>
6199 There used to be another directory, <file>/etc/rc.boot</file>,
6200 which contained scripts which were run once per machine
6201 boot. This has been deprecated in favour of links from
6202 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6203 described in <ref id="/etc/init.d">. Packages must not
6204 place files in <file>/etc/rc.boot</file>.
6209 <heading>Example</heading>
6212 An example on which you can base your
6213 <file>/etc/init.d</file> scripts is found in
6214 <file>/etc/init.d/skeleton</file>.
6221 <heading>Console messages from <file>init.d</file> scripts</heading>
6224 This section describes the formats to be used for messages
6225 written to standard output by the <file>/etc/init.d</file>
6226 scripts. The intent is to improve the consistency of
6227 Debian's startup and shutdown look and feel. For this
6228 reason, please look very carefully at the details. We want
6229 the messages to have the same format in terms of wording,
6230 spaces, punctuation and case of letters.
6234 Here is a list of overall rules that should be used for
6235 messages generated by <file>/etc/init.d</file> scripts.
6241 The message should fit in one line (fewer than 80
6242 characters), start with a capital letter and end with
6243 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6247 If the script is performing some time consuming task in
6248 the background (not merely starting or stopping a
6249 program, for instance), an ellipsis (three dots:
6250 <tt>...</tt>) should be output to the screen, with no
6251 leading or tailing whitespace or line feeds.
6255 The messages should appear as if the computer is telling
6256 the user what it is doing (politely :-), but should not
6257 mention "it" directly. For example, instead of:
6258 <example compact="compact">
6259 I'm starting network daemons: nfsd mountd.
6261 the message should say
6262 <example compact="compact">
6263 Starting network daemons: nfsd mountd.
6270 <tt>init.d</tt> script should use the following standard
6271 message formats for the situations enumerated below.
6277 <p>When daemons are started</p>
6280 If the script starts one or more daemons, the output
6281 should look like this (a single line, no leading
6283 <example compact="compact">
6284 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6286 The <var>description</var> should describe the
6287 subsystem the daemon or set of daemons are part of,
6288 while <var>daemon-1</var> up to <var>daemon-n</var>
6289 denote each daemon's name (typically the file name of
6294 For example, the output of <file>/etc/init.d/lpd</file>
6296 <example compact="compact">
6297 Starting printer spooler: lpd.
6302 This can be achieved by saying
6303 <example compact="compact">
6304 echo -n "Starting printer spooler: lpd"
6305 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6308 in the script. If there are more than one daemon to
6309 start, the output should look like this:
6310 <example compact="compact">
6311 echo -n "Starting remote file system services:"
6312 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6313 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6314 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6317 This makes it possible for the user to see what is
6318 happening and when the final daemon has been started.
6319 Care should be taken in the placement of white spaces:
6320 in the example above the system administrators can
6321 easily comment out a line if they don't want to start
6322 a specific daemon, while the displayed message still
6328 <p>When a system parameter is being set</p>
6331 If you have to set up different system parameters
6332 during the system boot, you should use this format:
6333 <example compact="compact">
6334 Setting <var>parameter</var> to "<var>value</var>".
6339 You can use a statement such as the following to get
6341 <example compact="compact">
6342 echo "Setting DNS domainname to \"$domainname\"."
6347 Note that the same symbol (<tt>"</tt>) is used for the left
6348 and right quotation marks. A grave accent (<tt>`</tt>) is
6349 not a quote character; neither is an apostrophe
6355 <p>When a daemon is stopped or restarted</p>
6358 When you stop or restart a daemon, you should issue a
6359 message identical to the startup message, except that
6360 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6361 or <tt>Restarting</tt> respectively.
6365 For example, stopping the printer daemon will look like
6367 <example compact="compact">
6368 Stopping printer spooler: lpd.
6374 <p>When something is executed</p>
6377 There are several examples where you have to run a
6378 program at system startup or shutdown to perform a
6379 specific task, for example, setting the system's clock
6380 using <prgn>netdate</prgn> or killing all processes
6381 when the system shuts down. Your message should look
6383 <example compact="compact">
6384 Doing something very useful...done.
6386 You should print the <tt>done.</tt> immediately after
6387 the job has been completed, so that the user is
6388 informed why they have to wait. You can get this
6390 <example compact="compact">
6391 echo -n "Doing something very useful..."
6400 <p>When the configuration is reloaded</p>
6403 When a daemon is forced to reload its configuration
6404 files you should use the following format:
6405 <example compact="compact">
6406 Reloading <var>description</var> configuration...done.
6408 where <var>description</var> is the same as in the
6409 daemon starting message.
6417 <heading>Cron jobs</heading>
6420 Packages must not modify the configuration file
6421 <file>/etc/crontab</file>, and they must not modify the files in
6422 <file>/var/spool/cron/crontabs</file>.</p>
6425 If a package wants to install a job that has to be executed
6426 via cron, it should place a file with the name of the
6427 package in one or more of the following directories:
6428 <example compact="compact">
6434 As these directory names imply, the files within them are
6435 executed on an hourly, daily, weekly, or monthly basis,
6436 respectively. The exact times are listed in
6437 <file>/etc/crontab</file>.</p>
6440 All files installed in any of these directories must be
6441 scripts (e.g., shell scripts or Perl scripts) so that they
6442 can easily be modified by the local system administrator.
6443 In addition, they must be treated as configuration files.
6447 If a certain job has to be executed at some other frequency or
6448 at a specific time, the package should install a file
6449 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6450 same syntax as <file>/etc/crontab</file> and is processed by
6451 <prgn>cron</prgn> automatically. The file must also be
6452 treated as a configuration file. (Note that entries in the
6453 <file>/etc/cron.d</file> directory are not handled by
6454 <prgn>anacron</prgn>. Thus, you should only use this
6455 directory for jobs which may be skipped if the system is not
6459 The scripts or crontab entries in these directories should
6460 check if all necessary programs are installed before they
6461 try to execute them. Otherwise, problems will arise when a
6462 package was removed but not purged since configuration files
6463 are kept on the system in this situation.</p>
6467 <heading>Menus</heading>
6470 The Debian <tt>menu</tt> package provides a standard
6471 interface between packages providing applications and
6472 <em>menu programs</em> (either X window managers or
6473 text-based menu programs such as <prgn>pdmenu</prgn>).
6477 All packages that provide applications that need not be
6478 passed any special command line arguments for normal
6479 operation should register a menu entry for those
6480 applications, so that users of the <tt>menu</tt> package
6481 will automatically get menu entries in their window
6482 managers, as well in shells like <tt>pdmenu</tt>.
6486 Menu entries should follow the current menu policy.
6490 The menu policy can be found in the <tt>menu-policy</tt>
6491 files in the <tt>debian-policy</tt> package.
6492 It is also available from the Debian web mirrors at
6493 <tt><url name="/doc/packaging-manuals/menu-policy/"
6494 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6498 Please also refer to the <em>Debian Menu System</em>
6499 documentation that comes with the <package>menu</package>
6500 package for information about how to register your
6506 <heading>Multimedia handlers</heading>
6509 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6510 is a mechanism for encoding files and data streams and
6511 providing meta-information about them, in particular their
6512 type (e.g. audio or video) and format (e.g. PNG, HTML,
6517 Registration of MIME type handlers allows programs like mail
6518 user agents and web browsers to invoke these handlers to
6519 view, edit or display MIME types they don't support directly.
6523 Packages which provide the ability to view/show/play,
6524 compose, edit or print MIME types should register themselves
6525 as such following the current MIME support policy.
6529 The MIME support policy can be found in the <tt>mime-policy</tt>
6530 files in the <tt>debian-policy</tt> package.
6531 It is also available from the Debian web mirrors at
6532 <tt><url name="/doc/packaging-manuals/mime-policy/"
6533 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6539 <heading>Keyboard configuration</heading>
6542 To achieve a consistent keyboard configuration so that all
6543 applications interpret a keyboard event the same way, all
6544 programs in the Debian distribution must be configured to
6545 comply with the following guidelines.
6549 The following keys must have the specified interpretations:
6552 <tag><tt><--</tt></tag>
6553 <item>delete the character to the left of the cursor</item>
6555 <tag><tt>Delete</tt></tag>
6556 <item>delete the character to the right of the cursor</item>
6558 <tag><tt>Control+H</tt></tag>
6559 <item>emacs: the help prefix</item>
6562 The interpretation of any keyboard events should be
6563 independent of the terminal that is used, be it a virtual
6564 console, an X terminal emulator, an rlogin/telnet session,
6569 The following list explains how the different programs
6570 should be set up to achieve this:
6576 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6580 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6584 X translations are set up to make
6585 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6586 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6587 is the vt220 escape code for the "delete character"
6588 key). This must be done by loading the X resources
6589 using <prgn>xrdb</prgn> on all local X displays, not
6590 using the application defaults, so that the
6591 translation resources used correspond to the
6592 <prgn>xmodmap</prgn> settings.
6596 The Linux console is configured to make
6597 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6598 generate <tt>ESC [ 3 ~</tt>.
6602 X applications are configured so that <tt><</tt>
6603 deletes left, and <tt>Delete</tt> deletes right. Motif
6604 applications already work like this.
6608 Terminals should have <tt>stty erase ^?</tt> .
6612 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6613 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6614 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6618 Emacs is programmed to map <tt>KB_Backspace</tt> or
6619 the <tt>stty erase</tt> character to
6620 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6621 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6622 <tt>^H</tt> to <tt>help</tt> as always.
6626 Other applications use the <tt>stty erase</tt>
6627 character and <tt>kdch1</tt> for the two delete keys,
6628 with ASCII DEL being "delete previous character" and
6629 <tt>kdch1</tt> being "delete character under
6637 This will solve the problem except for the following
6644 Some terminals have a <tt><--</tt> key that cannot
6645 be made to produce anything except <tt>^H</tt>. On
6646 these terminals Emacs help will be unavailable on
6647 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6648 character takes precedence in Emacs, and has been set
6649 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6650 available) can be used instead.
6654 Some operating systems use <tt>^H</tt> for <tt>stty
6655 erase</tt>. However, modern telnet versions and all
6656 rlogin versions propagate <tt>stty</tt> settings, and
6657 almost all UNIX versions honour <tt>stty erase</tt>.
6658 Where the <tt>stty</tt> settings are not propagated
6659 correctly, things can be made to work by using
6660 <tt>stty</tt> manually.
6664 Some systems (including previous Debian versions) use
6665 <prgn>xmodmap</prgn> to arrange for both
6666 <tt><--</tt> and <tt>Delete</tt> to generate
6667 <tt>KB_Delete</tt>. We can change the behavior of
6668 their X clients using the same X resources that we use
6669 to do it for our own clients, or configure our clients
6670 using their resources when things are the other way
6671 around. On displays configured like this
6672 <tt>Delete</tt> will not work, but <tt><--</tt>
6677 Some operating systems have different <tt>kdch1</tt>
6678 settings in their <tt>terminfo</tt> database for
6679 <tt>xterm</tt> and others. On these systems the
6680 <tt>Delete</tt> key will not work correctly when you
6681 log in from a system conforming to our policy, but
6682 <tt><--</tt> will.
6689 <heading>Environment variables</heading>
6692 A program must not depend on environment variables to get
6693 reasonable defaults. (That's because these environment
6694 variables would have to be set in a system-wide
6695 configuration file like <file>/etc/profile</file>, which is not
6696 supported by all shells.)
6700 If a program usually depends on environment variables for its
6701 configuration, the program should be changed to fall back to
6702 a reasonable default configuration if these environment
6703 variables are not present. If this cannot be done easily
6704 (e.g., if the source code of a non-free program is not
6705 available), the program must be replaced by a small
6706 "wrapper" shell script which sets the environment variables
6707 if they are not already defined, and calls the original program.
6711 Here is an example of a wrapper script for this purpose:
6713 <example compact="compact">
6715 BAR=${BAR:-/var/lib/fubar}
6717 exec /usr/lib/foo/foo "$@"
6722 Furthermore, as <file>/etc/profile</file> is a configuration
6723 file of the <prgn>base-files</prgn> package, other packages must
6724 not put any environment variables or other commands into that
6729 <sect id="doc-base">
6730 <heading>Registering Documents using doc-base</heading>
6733 The <package>doc-base</package> package implements a
6734 flexible mechanism for handling and presenting
6735 documentation. The recommended practice is for every Debian
6736 package that provides online documentation (other than just
6737 manual pages) to register these documents with
6738 <package>doc-base</package> by installing a
6739 <package>doc-base</package> control file via the
6740 <prgn/install-docs/ script at installation time and
6741 de-register the manuals again when the package is removed.
6744 Please refer to the documentation that comes with the
6745 <package>doc-base</package> package for information and
6754 <heading>Files</heading>
6757 <heading>Binaries</heading>
6760 Two different packages must not install programs with
6761 different functionality but with the same filenames. (The
6762 case of two programs having the same functionality but
6763 different implementations is handled via "alternatives" or
6764 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6765 <ref id="conflicts"> respectively.) If this case happens,
6766 one of the programs must be renamed. The maintainers should
6767 report this to the <tt>debian-devel</tt> mailing list and
6768 try to find a consensus about which program will have to be
6769 renamed. If a consensus cannot be reached, <em>both</em>
6770 programs must be renamed.
6774 By default, when a package is being built, any binaries
6775 created should include debugging information, as well as
6776 being compiled with optimization. You should also turn on
6777 as many reasonable compilation warnings as possible; this
6778 makes life easier for porters, who can then look at build
6779 logs for possible problems. For the C programming language,
6780 this means the following compilation parameters should be
6782 <example compact="compact">
6784 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6786 INSTALL = install -s # (or use strip on the files in debian/tmp)
6791 Note that by default all installed binaries should be stripped,
6792 either by using the <tt>-s</tt> flag to
6793 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6794 the binaries after they have been copied into
6795 <file>debian/tmp</file> but before the tree is made into a
6800 Although binaries in the build tree should be compiled with
6801 debugging information by default, it can often be difficult to
6802 debug programs if they are also subjected to compiler
6803 optimization. For this reason, it is recommended to support the
6804 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6805 (see <ref id="debianrules-options">). This variable can contain
6806 several flags to change how a package is compiled and built.
6810 It is up to the package maintainer to decide what
6811 compilation options are best for the package. Certain
6812 binaries (such as computationally-intensive programs) will
6813 function better with certain flags (<tt>-O3</tt>, for
6814 example); feel free to use them. Please use good judgment
6815 here. Don't use flags for the sake of it; only use them
6816 if there is good reason to do so. Feel free to override
6817 the upstream author's ideas about which compilation
6818 options are best: they are often inappropriate for our
6824 <sect id="libraries">
6825 <heading>Libraries</heading>
6828 If the package is <strong>architecture: any</strong>, then
6829 the shared library compilation and linking flags must have
6830 <tt>-fPIC</tt>, or the package shall not build on some of
6831 the supported architectures<footnote>
6833 If you are using GCC, <tt>-fPIC</tt> produces code with
6834 relocatable position independent code, which is required for
6835 most architectures to create a shared library, with i386 and
6836 perhaps some others where non position independent code is
6837 permitted in a shared library.
6840 Position independent code may have a performance penalty,
6841 especially on <tt>i386</tt>. However, in most cases the
6842 speed penalty must be measured against the memory wasted on
6843 the few architectures where non position independent code is
6846 </footnote>. Any exception to this rule must be discussed on
6847 the mailing list <em>debian-devel@lists.debian.org</em>, and
6848 a rough consensus obtained. The reasons for not compiling
6849 with <tt>-fPIC</tt> flag must be recorded in the file
6850 <tt>README.Debian</tt>, and care must be taken to either
6851 restrict the architecture or arrange for <tt>-fPIC</tt> to
6852 be used on architectures where it is required.<footnote>
6854 Some of the reasons why this might be required is if the
6855 library contains hand crafted assembly code that is not
6856 relocatable, the speed penalty is excessive for compute
6857 intensive libs, and similar reasons.
6862 As to the static libraries, the common case is not to have
6863 relocatable code, since there is no benefit, unless in specific
6864 cases; therefore the static version must not be compiled
6865 with the <tt>-fPIC</tt> flag. Any exception to this rule
6866 should be discussed on the mailing list
6867 <em>debian-devel@lists.debian.org</em>, and the reasons for
6868 compiling with the <tt>-fPIC</tt> flag must be recorded in
6869 the file <tt>README.Debian</tt>. <footnote>
6871 Some of the reasons for linking static libraries with
6872 the <tt>-fPIC</tt> flag are if, for example, one needs a
6873 Perl API for a library that is under rapid development,
6874 and has an unstable API, so shared libraries are
6875 pointless at this phase of the library's development. In
6876 that case, since Perl needs a library with relocatable
6877 code, it may make sense to create a static library with
6878 relocatable code. Another reason cited is if you are
6879 distilling various libraries into a common shared
6880 library, like <tt>mklibs</tt> does in the Debian
6886 In other words, if both a shared and a static library is
6887 being built, each source unit (<tt>*.c</tt>, for example,
6888 for C files) will need to be compiled twice, for the normal
6892 You must specify the gcc option <tt>-D_REENTRANT</tt>
6893 when building a library (either static or shared) to make
6894 the library compatible with LinuxThreads.
6898 Although not enforced by the build tools, shared libraries
6899 must be linked against all libraries that they use symbols from
6900 in the same way that binaries are. This ensures the correct
6901 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6902 system and guarantees that all libraries can be safely opened
6903 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6904 option <tt>-Wl,-z,defs</tt> when building a shared library.
6905 Since this option enforces symbol resolution at build time,
6906 a missing library reference will be caught early as a fatal
6911 All installed shared libraries should be stripped with
6912 <example compact="compact">
6913 strip --strip-unneeded <var>your-lib</var>
6915 (The option <tt>--strip-unneeded</tt> makes
6916 <prgn>strip</prgn> remove only the symbols which aren't
6917 needed for relocation processing.) Shared libraries can
6918 function perfectly well when stripped, since the symbols for
6919 dynamic linking are in a separate part of the ELF object
6921 You might also want to use the options
6922 <tt>--remove-section=.comment</tt> and
6923 <tt>--remove-section=.note</tt> on both shared libraries
6924 and executables, and <tt>--strip-debug</tt> on static
6930 Note that under some circumstances it may be useful to
6931 install a shared library unstripped, for example when
6932 building a separate package to support debugging.
6936 Shared object files (often <file>.so</file> files) that are not
6937 public libraries, that is, they are not meant to be linked
6938 to by third party executables (binaries of other packages),
6939 should be installed in subdirectories of the
6940 <file>/usr/lib</file> directory. Such files are exempt from the
6941 rules that govern ordinary shared libraries, except that
6942 they must not be installed executable and should be
6944 A common example are the so-called "plug-ins",
6945 internal shared objects that are dynamically loaded by
6946 programs using <manref name="dlopen" section="3">.
6951 Packages containing shared libraries that may be linked to
6952 by other packages' binaries, but which for some
6953 <em>compelling</em> reason can not be installed in
6954 <file>/usr/lib</file> directory, may install the shared library
6955 files in subdirectories of the <file>/usr/lib</file> directory,
6956 in which case they should arrange to add that directory in
6957 <file>/etc/ld.so.conf</file> in the package's post-installation
6958 script, and remove it in the package's post-removal script.
6962 An ever increasing number of packages are using
6963 <prgn>libtool</prgn> to do their linking. The latest GNU
6964 libtools (>= 1.3a) can take advantage of the metadata in the
6965 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6966 files). The main advantage of <prgn>libtool</prgn>'s
6967 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6968 store and subsequently access metadata with respect to the
6969 libraries it builds. <prgn>libtool</prgn> will search for
6970 those files, which contain a lot of useful information about
6971 a library (such as library dependency information for static
6972 linking). Also, they're <em>essential</em> for programs
6973 using <tt>libltdl</tt>.<footnote>
6974 Although <prgn>libtool</prgn> is fully capable of
6975 linking against shared libraries which don't have
6976 <tt>.la</tt> files, as it is a mere shell script it can
6977 add considerably to the build time of a
6978 <prgn>libtool</prgn>-using package if that shell script
6979 has to derive all this information from first principles
6980 for each library every time it is linked. With the
6981 advent of <prgn>libtool</prgn> version 1.4 (and to a
6982 lesser extent <prgn>libtool</prgn> version 1.3), the
6983 <file>.la</file> files also store information about
6984 inter-library dependencies which cannot necessarily be
6985 derived after the <file>.la</file> file is deleted.
6990 Packages that use <prgn>libtool</prgn> to create shared
6991 libraries should include the <file>.la</file> files in the
6992 <tt>-dev</tt> package, unless the package relies on
6993 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6994 the <tt>.la</tt> files must go in the run-time library
6999 You must make sure that you use only released versions of
7000 shared libraries to build your packages; otherwise other
7001 users will not be able to run your binaries
7002 properly. Producing source packages that depend on
7003 unreleased compilers is also usually a bad
7010 <heading>Shared libraries</heading>
7012 This section has moved to <ref id="sharedlibs">.
7018 <heading>Scripts</heading>
7021 All command scripts, including the package maintainer
7022 scripts inside the package and used by <prgn>dpkg</prgn>,
7023 should have a <tt>#!</tt> line naming the shell to be used
7028 In the case of Perl scripts this should be
7029 <tt>#!/usr/bin/perl</tt>.
7033 When scripts are installed into a directory in the system
7034 PATH, the script name should not include an extension such
7035 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7036 language currently used to implement it.
7039 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7040 should almost certainly start with <tt>set -e</tt> so that
7041 errors are detected. Every script should use
7042 <tt>set -e</tt> or check the exit status of <em>every</em>
7047 Scripts may assume that <file>/bin/sh</file> implements the
7048 SUSv3 Shell Command Language<footnote>
7049 Single UNIX Specification, version 3, which is also IEEE
7050 1003.1-2004 (POSIX), and is available on the World Wide Web
7051 from <url id="http://www.unix.org/version3/online.html"
7052 name="The Open Group"> after free
7053 registration.</footnote>
7054 plus the following additional features not mandated by
7056 These features are in widespread use in the Linux community
7057 and are implemented in all of bash, dash, and ksh, the most
7058 common shells users may wish to use as <file>/bin/sh</file>.
7061 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7062 must not generate a newline.</item>
7063 <item><tt>test</tt>, if implemented as a shell built-in, must
7064 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7066 <item><tt>local</tt> to create a scoped variable must be
7067 supported, including listing multiple variables in a single
7068 local command and assigning a value to a variable at the
7069 same time as localizing it. <tt>local</tt> may or
7070 may not preserve the variable value from an outer scope if
7071 no assignment is present. Uses such as:
7075 # ... use a, b, c, d ...
7078 must be supported and must set the value of <tt>c</tt> to
7082 If a shell script requires non-SUSv3 features from the shell
7083 interpreter other than those listed above, the appropriate shell
7084 must be specified in the first line of the script (e.g.,
7085 <tt>#!/bin/bash</tt>) and the package must depend on the package
7086 providing the shell (unless the shell package is marked
7087 "Essential", as in the case of <prgn>bash</prgn>).
7091 You may wish to restrict your script to SUSv3 features plus the
7092 above set when possible so that it may use <file>/bin/sh</file>
7093 as its interpreter. If your script works with <prgn>dash</prgn>
7094 (originally called <prgn>ash</prgn>), it probably complies with
7095 the above requirements, but if you are in doubt, use
7096 <file>/bin/bash</file>.
7100 Perl scripts should check for errors when making any
7101 system calls, including <tt>open</tt>, <tt>print</tt>,
7102 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7106 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7107 scripting languages. See <em>Csh Programming Considered
7108 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7109 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7110 If an upstream package comes with <prgn>csh</prgn> scripts
7111 then you must make sure that they start with
7112 <tt>#!/bin/csh</tt> and make your package depend on the
7113 <prgn>c-shell</prgn> virtual package.
7117 Any scripts which create files in world-writeable
7118 directories (e.g., in <file>/tmp</file>) must use a
7119 mechanism which will fail atomically if a file with the same
7120 name already exists.
7124 The Debian base system provides the <prgn>tempfile</prgn>
7125 and <prgn>mktemp</prgn> utilities for use by scripts for
7132 <heading>Symbolic links</heading>
7135 In general, symbolic links within a top-level directory
7136 should be relative, and symbolic links pointing from one
7137 top-level directory into another should be absolute. (A
7138 top-level directory is a sub-directory of the root
7139 directory <file>/</file>.)
7143 In addition, symbolic links should be specified as short as
7144 possible, i.e., link targets like <file>foo/../bar</file> are
7149 Note that when creating a relative link using
7150 <prgn>ln</prgn> it is not necessary for the target of the
7151 link to exist relative to the working directory you're
7152 running <prgn>ln</prgn> from, nor is it necessary to change
7153 directory to the directory where the link is to be made.
7154 Simply include the string that should appear as the target
7155 of the link (this will be a pathname relative to the
7156 directory in which the link resides) as the first argument
7161 For example, in your <prgn>Makefile</prgn> or
7162 <file>debian/rules</file>, you can do things like:
7163 <example compact="compact">
7164 ln -fs gcc $(prefix)/bin/cc
7165 ln -fs gcc debian/tmp/usr/bin/cc
7166 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7167 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7172 A symbolic link pointing to a compressed file should always
7173 have the same file extension as the referenced file. (For
7174 example, if a file <file>foo.gz</file> is referenced by a
7175 symbolic link, the filename of the link has to end with
7176 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7181 <heading>Device files</heading>
7184 Packages must not include device files in the package file
7189 If a package needs any special device files that are not
7190 included in the base system, it must call
7191 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7192 after notifying the user<footnote>
7193 This notification could be done via a (low-priority)
7194 debconf message, or an echo (printf) statement.
7199 Packages must not remove any device files in the
7200 <prgn>postrm</prgn> or any other script. This is left to the
7201 system administrator.
7205 Debian uses the serial devices
7206 <file>/dev/ttyS*</file>. Programs using the old
7207 <file>/dev/cu*</file> devices should be changed to use
7208 <file>/dev/ttyS*</file>.
7212 <sect id="config-files">
7213 <heading>Configuration files</heading>
7216 <heading>Definitions</heading>
7220 <tag>configuration file</tag>
7222 A file that affects the operation of a program, or
7223 provides site- or host-specific information, or
7224 otherwise customizes the behavior of a program.
7225 Typically, configuration files are intended to be
7226 modified by the system administrator (if needed or
7227 desired) to conform to local policy or to provide
7228 more useful site-specific behavior.
7231 <tag><tt>conffile</tt></tag>
7233 A file listed in a package's <tt>conffiles</tt>
7234 file, and is treated specially by <prgn>dpkg</prgn>
7235 (see <ref id="configdetails">).
7241 The distinction between these two is important; they are
7242 not interchangeable concepts. Almost all
7243 <tt>conffile</tt>s are configuration files, but many
7244 configuration files are not <tt>conffiles</tt>.
7248 As noted elsewhere, <file>/etc/init.d</file> scripts,
7249 <file>/etc/default</file> files, scripts installed in
7250 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7251 configuration installed in <file>/etc/cron.d</file> must be
7252 treated as configuration files. In general, any script that
7253 embeds configuration information is de-facto a configuration
7254 file and should be treated as such.
7259 <heading>Location</heading>
7262 Any configuration files created or used by your package
7263 must reside in <file>/etc</file>. If there are several,
7264 consider creating a subdirectory of <file>/etc</file>
7265 named after your package.
7269 If your package creates or uses configuration files
7270 outside of <file>/etc</file>, and it is not feasible to modify
7271 the package to use <file>/etc</file> directly, put the files
7272 in <file>/etc</file> and create symbolic links to those files
7273 from the location that the package requires.
7278 <heading>Behavior</heading>
7281 Configuration file handling must conform to the following
7283 <list compact="compact">
7285 local changes must be preserved during a package
7289 configuration files must be preserved when the
7290 package is removed, and only deleted when the
7297 The easy way to achieve this behavior is to make the
7298 configuration file a <tt>conffile</tt>. This is
7299 appropriate only if it is possible to distribute a default
7300 version that will work for most installations, although
7301 some system administrators may choose to modify it. This
7302 implies that the default version will be part of the
7303 package distribution, and must not be modified by the
7304 maintainer scripts during installation (or at any other
7309 In order to ensure that local changes are preserved
7310 correctly, no package may contain or make hard links to
7311 conffiles.<footnote>
7312 Rationale: There are two problems with hard links.
7313 The first is that some editors break the link while
7314 editing one of the files, so that the two files may
7315 unwittingly become unlinked and different. The second
7316 is that <prgn>dpkg</prgn> might break the hard link
7317 while upgrading <tt>conffile</tt>s.
7322 The other way to do it is via the maintainer scripts. In
7323 this case, the configuration file must not be listed as a
7324 <tt>conffile</tt> and must not be part of the package
7325 distribution. If the existence of a file is required for
7326 the package to be sensibly configured it is the
7327 responsibility of the package maintainer to provide
7328 maintainer scripts which correctly create, update and
7329 maintain the file and remove it on purge. (See <ref
7330 id="maintainerscripts"> for more information.) These
7331 scripts must be idempotent (i.e., must work correctly if
7332 <prgn>dpkg</prgn> needs to re-run them due to errors
7333 during installation or removal), must cope with all the
7334 variety of ways <prgn>dpkg</prgn> can call maintainer
7335 scripts, must not overwrite or otherwise mangle the user's
7336 configuration without asking, must not ask unnecessary
7337 questions (particularly during upgrades), and must
7338 otherwise be good citizens.
7342 The scripts are not required to configure every possible
7343 option for the package, but only those necessary to get
7344 the package running on a given system. Ideally the
7345 sysadmin should not have to do any configuration other
7346 than that done (semi-)automatically by the
7347 <prgn>postinst</prgn> script.
7351 A common practice is to create a script called
7352 <file><var>package</var>-configure</file> and have the
7353 package's <prgn>postinst</prgn> call it if and only if the
7354 configuration file does not already exist. In certain
7355 cases it is useful for there to be an example or template
7356 file which the maintainer scripts use. Such files should
7357 be in <file>/usr/share/<var>package</var></file> or
7358 <file>/usr/lib/<var>package</var></file> (depending on whether
7359 they are architecture-independent or not). There should
7360 be symbolic links to them from
7361 <file>/usr/share/doc/<var>package</var>/examples</file> if
7362 they are examples, and should be perfectly ordinary
7363 <prgn>dpkg</prgn>-handled files (<em>not</em>
7364 configuration files).
7368 These two styles of configuration file handling must
7369 not be mixed, for that way lies madness:
7370 <prgn>dpkg</prgn> will ask about overwriting the file
7371 every time the package is upgraded.
7376 <heading>Sharing configuration files</heading>
7379 Packages which specify the same file as a
7380 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7381 with each other. (This is an instance of the general rule
7382 about not sharing files. Note that neither alternatives
7383 nor diversions are likely to be appropriate in this case;
7384 in particular, <prgn>dpkg</prgn> does not handle diverted
7385 <tt>conffile</tt>s well.)
7389 The maintainer scripts must not alter a <tt>conffile</tt>
7390 of <em>any</em> package, including the one the scripts
7395 If two or more packages use the same configuration file
7396 and it is reasonable for both to be installed at the same
7397 time, one of these packages must be defined as
7398 <em>owner</em> of the configuration file, i.e., it will be
7399 the package which handles that file as a configuration
7400 file. Other packages that use the configuration file must
7401 depend on the owning package if they require the
7402 configuration file to operate. If the other package will
7403 use the configuration file if present, but is capable of
7404 operating without it, no dependency need be declared.
7408 If it is desirable for two or more related packages to
7409 share a configuration file <em>and</em> for all of the
7410 related packages to be able to modify that configuration
7411 file, then the following should be done:
7412 <enumlist compact="compact">
7414 One of the related packages (the "owning" package)
7415 will manage the configuration file with maintainer
7416 scripts as described in the previous section.
7419 The owning package should also provide a program
7420 that the other packages may use to modify the
7424 The related packages must use the provided program
7425 to make any desired modifications to the
7426 configuration file. They should either depend on
7427 the core package to guarantee that the configuration
7428 modifier program is available or accept gracefully
7429 that they cannot modify the configuration file if it
7430 is not. (This is in addition to the fact that the
7431 configuration file may not even be present in the
7438 Sometimes it's appropriate to create a new package which
7439 provides the basic infrastructure for the other packages
7440 and which manages the shared configuration files. (The
7441 <tt>sgml-base</tt> package is a good example.)
7446 <heading>User configuration files ("dotfiles")</heading>
7449 The files in <file>/etc/skel</file> will automatically be
7450 copied into new user accounts by <prgn>adduser</prgn>.
7451 No other program should reference the files in
7452 <file>/etc/skel</file>.
7456 Therefore, if a program needs a dotfile to exist in
7457 advance in <file>$HOME</file> to work sensibly, that dotfile
7458 should be installed in <file>/etc/skel</file> and treated as a
7463 However, programs that require dotfiles in order to
7464 operate sensibly are a bad thing, unless they do create
7465 the dotfiles themselves automatically.
7469 Furthermore, programs should be configured by the Debian
7470 default installation to behave as closely to the upstream
7471 default behavior as possible.
7475 Therefore, if a program in a Debian package needs to be
7476 configured in some way in order to operate sensibly, that
7477 should be done using a site-wide configuration file placed
7478 in <file>/etc</file>. Only if the program doesn't support a
7479 site-wide default configuration and the package maintainer
7480 doesn't have time to add it may a default per-user file be
7481 placed in <file>/etc/skel</file>.
7485 <file>/etc/skel</file> should be as empty as we can make it.
7486 This is particularly true because there is no easy (or
7487 necessarily desirable) mechanism for ensuring that the
7488 appropriate dotfiles are copied into the accounts of
7489 existing users when a package is installed.
7495 <heading>Log files</heading>
7497 Log files should usually be named
7498 <file>/var/log/<var>package</var>.log</file>. If you have many
7499 log files, or need a separate directory for permission
7500 reasons (<file>/var/log</file> is writable only by
7501 <file>root</file>), you should usually create a directory named
7502 <file>/var/log/<var>package</var></file> and place your log
7507 Log files must be rotated occasionally so that they don't
7508 grow indefinitely; the best way to do this is to drop a log
7509 rotation configuration file into the directory
7510 <file>/etc/logrotate.d</file> and use the facilities provided by
7511 logrotate.<footnote>
7513 The traditional approach to log files has been to set up
7514 <em>ad hoc</em> log rotation schemes using simple shell
7515 scripts and cron. While this approach is highly
7516 customizable, it requires quite a lot of sysadmin work.
7517 Even though the original Debian system helped a little
7518 by automatically installing a system which can be used
7519 as a template, this was deemed not enough.
7523 The use of <prgn>logrotate</prgn>, a program developed
7524 by Red Hat, is better, as it centralizes log management.
7525 It has both a configuration file
7526 (<file>/etc/logrotate.conf</file>) and a directory where
7527 packages can drop their individual log rotation
7528 configurations (<file>/etc/logrotate.d</file>).
7531 Here is a good example for a logrotate config
7532 file (for more information see <manref name="logrotate"
7534 <example compact="compact">
7535 /var/log/foo/*.log {
7540 /etc/init.d/foo force-reload
7544 This rotates all files under <file>/var/log/foo</file>, saves 12
7545 compressed generations, and forces the daemon to reload its
7546 configuration information after the log rotation.
7550 Log files should be removed when the package is
7551 purged (but not when it is only removed). This should be
7552 done by the <prgn>postrm</prgn> script when it is called
7553 with the argument <tt>purge</tt> (see <ref
7554 id="removedetails">).
7559 <heading>Permissions and owners</heading>
7562 The rules in this section are guidelines for general use.
7563 If necessary you may deviate from the details below.
7564 However, if you do so you must make sure that what is done
7565 is secure and you should try to be as consistent as possible
7566 with the rest of the system. You should probably also
7567 discuss it on <prgn>debian-devel</prgn> first.
7571 Files should be owned by <tt>root:root</tt>, and made
7572 writable only by the owner and universally readable (and
7573 executable, if appropriate), that is mode 644 or 755.
7577 Directories should be mode 755 or (for group-writability)
7578 mode 2775. The ownership of the directory should be
7579 consistent with its mode: if a directory is mode 2775, it
7580 should be owned by the group that needs write access to
7583 When a package is upgraded, and the owner or permissions
7584 of a file included in the package has changed, dpkg
7585 arranges for the ownership and permissions to be
7586 correctly set upon installation. However, this does not
7587 extend to directories; the permissions and ownership of
7588 directories already on the system does not change on
7589 install or upgrade of packages. This makes sense, since
7590 otherwise common directories like <tt>/usr</tt> would
7591 always be in flux. To correctly change permissions of a
7592 directory the package owns, explicit action is required,
7593 usually in the <tt>postinst</tt> script. Care must be
7594 taken to handle downgrades as well, in that case.
7601 Setuid and setgid executables should be mode 4755 or 2755
7602 respectively, and owned by the appropriate user or group.
7603 They should not be made unreadable (modes like 4711 or
7604 2711 or even 4111); doing so achieves no extra security,
7605 because anyone can find the binary in the freely available
7606 Debian package; it is merely inconvenient. For the same
7607 reason you should not restrict read or execute permissions
7608 on non-set-id executables.
7612 Some setuid programs need to be restricted to particular
7613 sets of users, using file permissions. In this case they
7614 should be owned by the uid to which they are set-id, and by
7615 the group which should be allowed to execute them. They
7616 should have mode 4754; again there is no point in making
7617 them unreadable to those users who must not be allowed to
7622 It is possible to arrange that the system administrator can
7623 reconfigure the package to correspond to their local
7624 security policy by changing the permissions on a binary:
7625 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7626 described below.<footnote>
7627 Ordinary files installed by <prgn>dpkg</prgn> (as
7628 opposed to <tt>conffile</tt>s and other similar objects)
7629 normally have their permissions reset to the distributed
7630 permissions when the package is reinstalled. However,
7631 the use of <prgn>dpkg-statoverride</prgn> overrides this
7632 default behavior. If you use this method, you should
7633 remember to describe <prgn>dpkg-statoverride</prgn> in
7634 the package documentation; being a relatively new
7635 addition to Debian, it is probably not yet well-known.
7637 Another method you should consider is to create a group for
7638 people allowed to use the program(s) and make any setuid
7639 executables executable only by that group.
7643 If you need to create a new user or group for your package
7644 there are two possibilities. Firstly, you may need to
7645 make some files in the binary package be owned by this
7646 user or group, or you may need to compile the user or
7647 group id (rather than just the name) into the binary
7648 (though this latter should be avoided if possible, as in
7649 this case you need a statically allocated id).</p>
7652 If you need a statically allocated id, you must ask for a
7653 user or group id from the <tt>base-passwd</tt> maintainer,
7654 and must not release the package until you have been
7655 allocated one. Once you have been allocated one you must
7656 either make the package depend on a version of the
7657 <tt>base-passwd</tt> package with the id present in
7658 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7659 your package to create the user or group itself with the
7660 correct id (using <tt>adduser</tt>) in its
7661 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7662 the <prgn>postinst</prgn> is to be preferred if it is
7663 possible, otherwise a pre-dependency will be needed on the
7664 <tt>adduser</tt> package.)
7668 On the other hand, the program might be able to determine
7669 the uid or gid from the user or group name at runtime, so
7670 that a dynamically allocated id can be used. In this case
7671 you should choose an appropriate user or group name,
7672 discussing this on <prgn>debian-devel</prgn> and checking
7673 with the <package/base-passwd/ maintainer that it is unique and that
7674 they do not wish you to use a statically allocated id
7675 instead. When this has been checked you must arrange for
7676 your package to create the user or group if necessary using
7677 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7678 <prgn>postinst</prgn> script (again, the latter is to be
7679 preferred if it is possible).
7683 Note that changing the numeric value of an id associated
7684 with a name is very difficult, and involves searching the
7685 file system for all appropriate files. You need to think
7686 carefully whether a static or dynamic id is required, since
7687 changing your mind later will cause problems.
7690 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7692 This section is not intended as policy, but as a
7693 description of the use of <prgn>dpkg-statoverride</prgn>.
7697 If a system administrator wishes to have a file (or
7698 directory or other such thing) installed with owner and
7699 permissions different from those in the distributed Debian
7700 package, they can use the <prgn>dpkg-statoverride</prgn>
7701 program to instruct <prgn>dpkg</prgn> to use the different
7702 settings every time the file is installed. Thus the
7703 package maintainer should distribute the files with their
7704 normal permissions, and leave it for the system
7705 administrator to make any desired changes. For example, a
7706 daemon which is normally required to be setuid root, but
7707 in certain situations could be used without being setuid,
7708 should be installed setuid in the <tt>.deb</tt>. Then the
7709 local system administrator can change this if they wish.
7710 If there are two standard ways of doing it, the package
7711 maintainer can use <tt>debconf</tt> to find out the
7712 preference, and call <prgn>dpkg-statoverride</prgn> in the
7713 maintainer script if necessary to accommodate the system
7714 administrator's choice. Care must be taken during
7715 upgrades to not override an existing setting.
7719 Given the above, <prgn>dpkg-statoverride</prgn> is
7720 essentially a tool for system administrators and would not
7721 normally be needed in the maintainer scripts. There is
7722 one type of situation, though, where calls to
7723 <prgn>dpkg-statoverride</prgn> would be needed in the
7724 maintainer scripts, and that involves packages which use
7725 dynamically allocated user or group ids. In such a
7726 situation, something like the following idiom can be very
7727 helpful in the package's <prgn>postinst</prgn>, where
7728 <tt>sysuser</tt> is a dynamically allocated id:
7730 for i in /usr/bin/foo /usr/sbin/bar
7732 # only do something when no setting exists
7733 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7735 #include: debconf processing, question about foo and bar
7736 if [ "$RET" = "true" ] ; then
7737 dpkg-statoverride --update --add sysuser root 4755 $i
7742 The corresponding <tt>dpkg-statoverride --remove</tt>
7743 calls can then be made unconditionally when the package is
7751 <chapt id="customized-programs">
7752 <heading>Customized programs</heading>
7754 <sect id="arch-spec">
7755 <heading>Architecture specification strings</heading>
7758 If a program needs to specify an <em>architecture specification
7759 string</em> in some place, it should select one of the
7760 strings provided by <tt>dpkg-architecture -L</tt>. The
7761 strings are in the format
7762 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7763 is sometimes elided, as when the OS is Linux.<footnote>
7764 <p>Currently, the strings are:
7765 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7766 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7767 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7768 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7769 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7770 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7771 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7772 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7773 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7774 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7775 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7776 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7777 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7778 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7779 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7780 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7781 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7782 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7783 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7784 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7785 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7786 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7787 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7788 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7789 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7790 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7791 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7792 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7793 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7794 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7795 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7796 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7797 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7798 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7799 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7800 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7801 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7807 Note that we don't want to use
7808 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7809 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7810 since this would make our programs incompatible with other
7811 Linux distributions. We also don't use something like
7812 <tt><var>arch</var>-unknown-linux</tt>, since the
7813 <tt>unknown</tt> does not look very good.
7818 <heading>Daemons</heading>
7821 The configuration files <file>/etc/services</file>,
7822 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7823 by the <prgn>netbase</prgn> package and must not be modified
7828 If a package requires a new entry in one of these files, the
7829 maintainer should get in contact with the
7830 <prgn>netbase</prgn> maintainer, who will add the entries
7831 and release a new version of the <prgn>netbase</prgn>
7836 The configuration file <file>/etc/inetd.conf</file> must not be
7837 modified by the package's scripts except via the
7838 <prgn>update-inetd</prgn> script or the
7839 <file>DebianNet.pm</file> Perl module. See their documentation
7840 for details on how to add entries.
7844 If a package wants to install an example entry into
7845 <file>/etc/inetd.conf</file>, the entry must be preceded with
7846 exactly one hash character (<tt>#</tt>). Such lines are
7847 treated as "commented out by user" by the
7848 <prgn>update-inetd</prgn> script and are not changed or
7849 activated during package updates.
7854 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7858 Some programs need to create pseudo-ttys. This should be done
7859 using Unix98 ptys if the C library supports it. The resulting
7860 program must not be installed setuid root, unless that
7861 is required for other functionality.
7865 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7866 <file>/var/log/lastlog</file> must be installed writable by
7867 group <tt>utmp</tt>. Programs which need to modify those
7868 files must be installed setgid <tt>utmp</tt>.
7873 <heading>Editors and pagers</heading>
7876 Some programs have the ability to launch an editor or pager
7877 program to edit or display a text document. Since there are
7878 lots of different editors and pagers available in the Debian
7879 distribution, the system administrator and each user should
7880 have the possibility to choose their preferred editor and
7885 In addition, every program should choose a good default
7886 editor/pager if none is selected by the user or system
7891 Thus, every program that launches an editor or pager must
7892 use the EDITOR or PAGER environment variable to determine
7893 the editor or pager the user wishes to use. If these
7894 variables are not set, the programs <file>/usr/bin/editor</file>
7895 and <file>/usr/bin/pager</file> should be used, respectively.
7899 These two files are managed through the <prgn>dpkg</prgn>
7900 "alternatives" mechanism. Thus every package providing an
7901 editor or pager must call the
7902 <prgn>update-alternatives</prgn> script to register these
7907 If it is very hard to adapt a program to make use of the
7908 EDITOR or PAGER variables, that program may be configured to
7909 use <file>/usr/bin/sensible-editor</file> and
7910 <file>/usr/bin/sensible-pager</file> as the editor or pager
7911 program respectively. These are two scripts provided in the
7912 Debian base system that check the EDITOR and PAGER variables
7913 and launch the appropriate program, and fall back to
7914 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7915 variable is not set.
7919 A program may also use the VISUAL environment variable to
7920 determine the user's choice of editor. If it exists, it
7921 should take precedence over EDITOR. This is in fact what
7922 <file>/usr/bin/sensible-editor</file> does.
7926 It is not required for a package to depend on
7927 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7928 package to provide such virtual packages.<footnote>
7929 The Debian base system already provides an editor and a
7935 <sect id="web-appl">
7936 <heading>Web servers and applications</heading>
7939 This section describes the locations and URLs that should
7940 be used by all web servers and web applications in the
7947 Cgi-bin executable files are installed in the
7949 <example compact="compact">
7950 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7952 and should be referred to as
7953 <example compact="compact">
7954 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7960 <p>Access to HTML documents</p>
7963 HTML documents for a package are stored in
7964 <file>/usr/share/doc/<var>package</var></file>
7965 and can be referred to as
7966 <example compact="compact">
7967 http://localhost/doc/<var>package</var>/<var>filename</var>
7972 The web server should restrict access to the document
7973 tree so that only clients on the same host can read
7974 the documents. If the web server does not support such
7975 access controls, then it should not provide access at
7976 all, or ask about providing access during installation.
7981 <p>Access to images</p>
7983 It is recommended that images for a package be stored
7984 in <tt>/usr/share/images/<var>package</var></tt> and
7985 may be referred to through an alias <tt>/images/</tt>
7988 http://localhost/images/<package>/<filename>
7995 <p>Web Document Root</p>
7998 Web Applications should try to avoid storing files in
7999 the Web Document Root. Instead they should use the
8000 /usr/share/doc/<var>package</var> directory for
8001 documents and register the Web Application via the
8002 <package>doc-base</package> package. If access to the
8003 web document root is unavoidable then use
8004 <example compact="compact">
8007 as the Document Root. This might be just a symbolic
8008 link to the location where the system administrator
8009 has put the real document root.
8012 <item><p>Providing httpd and/or httpd-cgi</p>
8014 All web servers should provide the virtual package
8015 <tt>httpd</tt>. If a web server has CGI support it should
8016 provide <tt>httpd-cgi</tt> additionally.
8019 All web applications which do not contain CGI scripts should
8020 depend on <tt>httpd</tt>, all those web applications which
8021 <tt>do</tt> contain CGI scripts, should depend on
8029 <sect id="mail-transport-agents">
8030 <heading>Mail transport, delivery and user agents</heading>
8033 Debian packages which process electronic mail, whether mail
8034 user agents (MUAs) or mail transport agents (MTAs), must
8035 ensure that they are compatible with the configuration
8036 decisions below. Failure to do this may result in lost
8037 mail, broken <tt>From:</tt> lines, and other serious brain
8042 The mail spool is <file>/var/mail</file> and the interface to
8043 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8044 the FHS). On older systems, the mail spool may be
8045 physically located in <file>/var/spool/mail</file>, but all
8046 access to the mail spool should be via the
8047 <file>/var/mail</file> symlink. The mail spool is part of the
8048 base system and not part of the MTA package.
8052 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8053 programs (such as IMAP daemons) must lock the mailbox in an
8054 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8055 be combined with dot locking. To avoid deadlocks, a program
8056 should use <tt>fcntl()</tt> first and dot locking after
8057 this, or alternatively implement the two locking methods in
8058 a non blocking way<footnote>
8059 If it is not possible to establish both locks, the
8060 system shouldn't wait for the second lock to be
8061 established, but remove the first lock, wait a (random)
8062 time, and start over locking again.
8063 </footnote>. Using the functions <tt>maillock</tt> and
8064 <tt>mailunlock</tt> provided by the
8065 <tt>liblockfile*</tt><footnote>
8066 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8067 to use these functions.
8068 </footnote> packages is the recommended way to realize this.
8072 Mailboxes are generally mode 660
8073 <tt><var>user</var>:mail</tt> unless the system
8074 administrator has chosen otherwise. A MUA may remove a
8075 mailbox (unless it has nonstandard permissions) in which
8076 case the MTA or another MUA must recreate it if needed.
8077 Mailboxes must be writable by group mail.
8081 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8082 be setgid mail to do the locking mentioned above (and
8083 must obviously avoid accessing other users' mailboxes
8084 using this privilege).</p>
8087 <file>/etc/aliases</file> is the source file for the system mail
8088 aliases (e.g., postmaster, usenet, etc.), it is the one
8089 which the sysadmin and <prgn>postinst</prgn> scripts may
8090 edit. After <file>/etc/aliases</file> is edited the program or
8091 human editing it must call <prgn>newaliases</prgn>. All MTA
8092 packages must come with a <prgn>newaliases</prgn> program,
8093 even if it does nothing, but older MTA packages did not do
8094 this so programs should not fail if <prgn>newaliases</prgn>
8095 cannot be found. Note that because of this, all MTA
8096 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8097 <tt>Replaces: mail-transport-agent</tt> control file
8102 The convention of writing <tt>forward to
8103 <var>address</var></tt> in the mailbox itself is not
8104 supported. Use a <tt>.forward</tt> file instead.</p>
8107 The <prgn>rmail</prgn> program used by UUCP
8108 for incoming mail should be <file>/usr/sbin/rmail</file>.
8109 Likewise, <prgn>rsmtp</prgn>, for receiving
8110 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8114 If your package needs to know what hostname to use on (for
8115 example) outgoing news and mail messages which are generated
8116 locally, you should use the file <file>/etc/mailname</file>. It
8117 will contain the portion after the username and <tt>@</tt>
8118 (at) sign for email addresses of users on the machine
8119 (followed by a newline).
8123 Such a package should check for the existence of this file
8124 when it is being configured. If it exists, it should be
8125 used without comment, although an MTA's configuration script
8126 may wish to prompt the user even if it finds that this file
8127 exists. If the file does not exist, the package should
8128 prompt the user for the value (preferably using
8129 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8130 as well as using it in the package's configuration. The
8131 prompt should make it clear that the name will not just be
8132 used by that package. For example, in this situation the
8133 <tt>inn</tt> package could say something like:
8134 <example compact="compact">
8135 Please enter the "mail name" of your system. This is the
8136 hostname portion of the address to be shown on outgoing
8137 news and mail messages. The default is
8138 <var>syshostname</var>, your system's host name. Mail
8139 name ["<var>syshostname</var>"]:
8141 where <var>syshostname</var> is the output of <tt>hostname
8147 <heading>News system configuration</heading>
8150 All the configuration files related to the NNTP (news)
8151 servers and clients should be located under
8152 <file>/etc/news</file>.</p>
8155 There are some configuration issues that apply to a number
8156 of news clients and server packages on the machine. These
8160 <tag><file>/etc/news/organization</file></tag>
8162 A string which should appear as the
8163 organization header for all messages posted
8164 by NNTP clients on the machine
8167 <tag><file>/etc/news/server</file></tag>
8169 Contains the FQDN of the upstream NNTP
8170 server, or localhost if the local machine is
8175 Other global files may be added as required for cross-package news
8182 <heading>Programs for the X Window System</heading>
8185 <heading>Providing X support and package priorities</heading>
8188 Programs that can be configured with support for the X
8189 Window System must be configured to do so and must declare
8190 any package dependencies necessary to satisfy their
8191 runtime requirements when using the X Window System. If
8192 such a package is of higher priority than the X packages
8193 on which it depends, it is required that either the
8194 X-specific components be split into a separate package, or
8195 that an alternative version of the package, which includes
8196 X support, be provided, or that the package's priority be
8202 <heading>Packages providing an X server</heading>
8205 Packages that provide an X server that, directly or
8206 indirectly, communicates with real input and display
8207 hardware should declare in their control data that they
8208 provide the virtual package <tt>xserver</tt>.<footnote>
8209 This implements current practice, and provides an
8210 actual policy for usage of the <tt>xserver</tt>
8211 virtual package which appears in the virtual packages
8212 list. In a nutshell, X servers that interface
8213 directly with the display and input hardware or via
8214 another subsystem (e.g., GGI) should provide
8215 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8216 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8222 <heading>Packages providing a terminal emulator</heading>
8225 Packages that provide a terminal emulator for the X Window
8226 System which meet the criteria listed below should declare
8227 in their control data that they provide the virtual
8228 package <tt>x-terminal-emulator</tt>. They should also
8229 register themselves as an alternative for
8230 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8235 To be an <tt>x-terminal-emulator</tt>, a program must:
8236 <list compact="compact">
8238 Be able to emulate a DEC VT100 terminal, or a
8239 compatible terminal.
8243 Support the command-line option <tt>-e
8244 <var>command</var></tt>, which creates a new
8245 terminal window<footnote>
8246 "New terminal window" does not necessarily mean
8247 a new top-level X window directly parented by
8248 the window manager; it could, if the terminal
8249 emulator application were so coded, be a new
8250 "view" in a multiple-document interface (MDI).
8252 and runs the specified <var>command</var>,
8253 interpreting the entirety of the rest of the command
8254 line as a command to pass straight to exec, in the
8255 manner that <tt>xterm</tt> does.
8259 Support the command-line option <tt>-T
8260 <var>title</var></tt>, which creates a new terminal
8261 window with the window title <var>title</var>.
8268 <heading>Packages providing a window manager</heading>
8271 Packages that provide a window manager should declare in
8272 their control data that they provide the virtual package
8273 <tt>x-window-manager</tt>. They should also register
8274 themselves as an alternative for
8275 <file>/usr/bin/x-window-manager</file>, with a priority
8276 calculated as follows:
8277 <list compact="compact">
8279 Start with a priority of 20.
8283 If the window manager supports the Debian menu
8284 system, add 20 points if this support is available
8285 in the package's default configuration (i.e., no
8286 configuration files belonging to the system or user
8287 have to be edited to activate the feature); if
8288 configuration files must be modified, add only 10
8294 If the window manager complies with <url
8295 id="http://www.freedesktop.org/Standards/wm-spec"
8296 name="The Window Manager Specification Project">,
8297 written by the <url id="http://www.freedesktop.org/"
8298 name="Free Desktop Group">, add 40 points.
8302 If the window manager permits the X session to be
8303 restarted using a <em>different</em> window manager
8304 (without killing the X server) in its default
8305 configuration, add 10 points; otherwise add none.
8312 <heading>Packages providing fonts</heading>
8315 Packages that provide fonts for the X Window
8317 For the purposes of Debian Policy, a "font for the X
8318 Window System" is one which is accessed via X protocol
8319 requests. Fonts for the Linux console, for PostScript
8320 renderer, or any other purpose, do not fit this
8321 definition. Any tool which makes such fonts available
8322 to the X Window System, however, must abide by this
8325 must do a number of things to ensure that they are both
8326 available without modification of the X or font server
8327 configuration, and that they do not corrupt files used by
8328 other font packages to register information about
8332 Fonts of any type supported by the X Window System
8333 must be in a separate binary package from any
8334 executables, libraries, or documentation (except
8335 that specific to the fonts shipped, such as their
8336 license information). If one or more of the fonts
8337 so packaged are necessary for proper operation of
8338 the package with which they are associated the font
8339 package may be Recommended; if the fonts merely
8340 provide an enhancement, a Suggests relationship may
8341 be used. Packages must not Depend on font
8343 This is because the X server may retrieve fonts
8344 from the local file system or over the network
8345 from an X font server; the Debian package system
8346 is empowered to deal only with the local
8352 BDF fonts must be converted to PCF fonts with the
8353 <prgn>bdftopcf</prgn> utility (available in the
8354 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8355 placed in a directory that corresponds to their
8357 <list compact="compact">
8359 100 dpi fonts must be placed in
8360 <file>/usr/share/fonts/X11/100dpi/</file>.
8364 75 dpi fonts must be placed in
8365 <file>/usr/share/fonts/X11/75dpi/</file>.
8369 Character-cell fonts, cursor fonts, and other
8370 low-resolution fonts must be placed in
8371 <file>/usr/share/fonts/X11/misc/</file>.
8377 Speedo fonts must be placed in
8378 <file>/usr/share/fonts/X11/Speedo/</file>.
8382 Type 1 fonts must be placed in
8383 <file>/usr/share/fonts/X11/Type1/</file>. If font
8384 metric files are available, they must be placed here
8389 Subdirectories of <file>/usr/share/fonts/X11/</file>
8390 other than those listed above must be neither
8391 created nor used. (The <file>PEX</file>, <file>CID</file>,
8392 and <file>cyrillic</file> directories are excepted for
8393 historical reasons, but installation of files into
8394 these directories remains discouraged.)
8398 Font packages may, instead of placing files directly
8399 in the X font directories listed above, provide
8400 symbolic links in that font directory pointing to
8401 the files' actual location in the filesystem. Such
8402 a location must comply with the FHS.
8406 Font packages should not contain both 75dpi and
8407 100dpi versions of a font. If both are available,
8408 they should be provided in separate binary packages
8409 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8410 the names of the packages containing the
8411 corresponding fonts.
8415 Fonts destined for the <file>misc</file> subdirectory
8416 should not be included in the same package as 75dpi
8417 or 100dpi fonts; instead, they should be provided in
8418 a separate package with <tt>-misc</tt> appended to
8423 Font packages must not provide the files
8424 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8425 <file>fonts.scale</file> in a font directory:
8428 <file>fonts.dir</file> files must not be provided at all.
8432 <file>fonts.alias</file> and <file>fonts.scale</file>
8433 files, if needed, should be provided in the
8435 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8436 where <var>fontdir</var> is the name of the
8438 <file>/usr/share/fonts/X11/</file> where the
8439 package's corresponding fonts are stored
8440 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8441 <var>package</var> is the name of the package
8442 that provides these fonts, and
8443 <var>extension</var> is either <tt>scale</tt>
8444 or <tt>alias</tt>, whichever corresponds to
8451 Font packages must declare a dependency on
8452 <tt>xfonts-utils</tt> in their control
8457 Font packages that provide one or more
8458 <file>fonts.scale</file> files as described above must
8459 invoke <prgn>update-fonts-scale</prgn> on each
8460 directory into which they installed fonts
8461 <em>before</em> invoking
8462 <prgn>update-fonts-dir</prgn> on that directory.
8463 This invocation must occur in both the
8464 <prgn>postinst</prgn> (for all arguments) and
8465 <prgn>postrm</prgn> (for all arguments except
8466 <tt>upgrade</tt>) scripts.
8470 Font packages that provide one or more
8471 <file>fonts.alias</file> files as described above must
8472 invoke <prgn>update-fonts-alias</prgn> on each
8473 directory into which they installed fonts. This
8474 invocation must occur in both the
8475 <prgn>postinst</prgn> (for all arguments) and
8476 <prgn>postrm</prgn> (for all arguments except
8477 <tt>upgrade</tt>) scripts.
8481 Font packages must invoke
8482 <prgn>update-fonts-dir</prgn> on each directory into
8483 which they installed fonts. This invocation must
8484 occur in both the <prgn>postinst</prgn> (for all
8485 arguments) and <prgn>postrm</prgn> (for all
8486 arguments except <tt>upgrade</tt>) scripts.
8490 Font packages must not provide alias names for the
8491 fonts they include which collide with alias names
8492 already in use by fonts already packaged.
8496 Font packages must not provide fonts with the same
8497 XLFD registry name as another font already packaged.
8504 <heading>Application defaults files</heading>
8507 Application defaults files must be installed in the
8508 directory <file>/etc/X11/app-defaults/</file> (use of a
8509 localized subdirectory of <file>/etc/X11/</file> as described
8510 in the <em>X Toolkit Intrinsics - C Language
8511 Interface</em> manual is also permitted). They must be
8512 registered as <tt>conffile</tt>s or handled as
8513 configuration files.
8517 Customization of programs' X resources may also be
8518 supported with the provision of a file with the same name
8519 as that of the package placed in the
8520 <file>/etc/X11/Xresources/</file> directory, which must
8521 registered as a <tt>conffile</tt> or handled as a
8522 configuration file.<footnote>
8523 Note that this mechanism is not the same as using
8524 app-defaults; app-defaults are tied to the client
8525 binary on the local file system, whereas X resources
8526 are stored in the X server and affect all connecting
8533 <heading>Installation directory issues</heading>
8536 Packages using the X Window System should not be
8537 configured to install files under the
8538 <file>/usr/X11R6/</file> directory. The
8539 <file>/usr/X11R6/</file> directory hierarchy should be
8540 regarded as obsolete.
8544 Programs that use GNU <prgn>autoconf</prgn> and
8545 <prgn>automake</prgn> are usually easily configured at
8546 compile time to use <file>/usr/</file> instead of
8547 <file>/usr/X11R6/</file>, and this should be done whenever
8548 possible. Configuration files for window managers and
8549 display managers should be placed in a subdirectory of
8550 <file>/etc/X11/</file> corresponding to the package name due
8551 to these programs' tight integration with the mechanisms
8552 of the X Window System. Application-level programs should
8553 use the <file>/etc/</file> directory unless otherwise mandated
8558 The installation of files into subdirectories
8559 of <file>/usr/X11R6/include/X11/</file> and
8560 <file>/usr/X11R6/lib/X11/</file> is now prohibited;
8561 package maintainers should determine if subdirectories of
8562 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8567 Packages should install any relevant files into the
8568 directories <file>/usr/include/X11/</file> and
8569 <file>/usr/lib/X11/</file>, but if they do so, they must
8570 pre-depend on <tt>x11-common (>=
8571 1:7.0.0)</tt><footnote>
8573 These libraries used to be all symbolic
8574 links. However, with <tt>X11R7</tt>,
8575 <tt>/usr/include/X11</tt> and <tt>/usr/lib/X11</tt>
8576 are now real directories, and packages
8577 <strong>should</strong> ship their files here instead
8578 of in <tt>/usr/X11R6/{include,lib}/X11</tt>.
8579 <tt>x11-common (>= 1:7.0.0) </tt> is the package
8580 responsible for converting these symlinks into
8588 <heading>The OSF/Motif and OpenMotif libraries</heading>
8591 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8592 OpenMotif libraries</em><footnote>
8593 OSF/Motif and OpenMotif are collectively referred to as
8594 "Motif" in this policy document.
8596 should be compiled against and tested with LessTif (a free
8597 re-implementation of Motif) instead. If the maintainer
8598 judges that the program or programs do not work
8599 sufficiently well with LessTif to be distributed and
8600 supported, but do so when compiled against Motif, then two
8601 versions of the package should be created; one linked
8602 statically against Motif and with <tt>-smotif</tt>
8603 appended to the package name, and one linked dynamically
8604 against Motif and with <tt>-dmotif</tt> appended to the
8609 Both Motif-linked versions are dependent
8610 upon non-DFSG-compliant software and thus cannot be
8611 uploaded to the <em>main</em> distribution; if the
8612 software is itself DFSG-compliant it may be uploaded to
8613 the <em>contrib</em> distribution. While known existing
8614 versions of Motif permit unlimited redistribution of
8615 binaries linked against the library (whether statically or
8616 dynamically), it is the package maintainer's
8617 responsibility to determine whether this is permitted by
8618 the license of the copy of Motif in their possession.
8624 <heading>Perl programs and modules</heading>
8627 Perl programs and modules should follow the current Perl policy.
8631 The Perl policy can be found in the <tt>perl-policy</tt>
8632 files in the <tt>debian-policy</tt> package.
8633 It is also available from the Debian web mirrors at
8634 <tt><url name="/doc/packaging-manuals/perl-policy/"
8635 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8640 <heading>Emacs lisp programs</heading>
8643 Please refer to the "Debian Emacs Policy" for details of how to
8644 package emacs lisp programs.
8648 The Emacs policy is available in
8649 <file>debian-emacs-policy.gz</file> of the
8650 <package>emacsen-common</package> package.
8651 It is also available from the Debian web mirrors at
8652 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8653 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8658 <heading>Games</heading>
8661 The permissions on <file>/var/games</file> are mode 755, owner
8662 <tt>root</tt> and group <tt>root</tt>.
8666 Each game decides on its own security policy.</p>
8669 Games which require protected, privileged access to
8670 high-score files, saved games, etc., may be made
8671 set-<em>group</em>-id (mode 2755) and owned by
8672 <tt>root:games</tt>, and use files and directories with
8673 appropriate permissions (770 <tt>root:games</tt>, for
8674 example). They must not be made
8675 set-<em>user</em>-id, as this causes security problems. (If
8676 an attacker can subvert any set-user-id game they can
8677 overwrite the executable of any other, causing other players
8678 of these games to run a Trojan horse program. With a
8679 set-group-id game the attacker only gets access to less
8680 important game data, and if they can get at the other
8681 players' accounts at all it will take considerably more
8685 Some packages, for example some fortune cookie programs, are
8686 configured by the upstream authors to install with their
8687 data files or other static information made unreadable so
8688 that they can only be accessed through set-id programs
8689 provided. You should not do this in a Debian package: anyone can
8690 download the <file>.deb</file> file and read the data from it,
8691 so there is no point making the files unreadable. Not
8692 making the files unreadable also means that you don't have
8693 to make so many programs set-id, which reduces the risk of a
8697 As described in the FHS, binaries of games should be
8698 installed in the directory <file>/usr/games</file>. This also
8699 applies to games that use the X Window System. Manual pages
8700 for games (X and non-X games) should be installed in
8701 <file>/usr/share/man/man6</file>.</p>
8707 <heading>Documentation</heading>
8710 <heading>Manual pages</heading>
8713 You should install manual pages in <prgn>nroff</prgn> source
8714 form, in appropriate places under <file>/usr/share/man</file>.
8715 You should only use sections 1 to 9 (see the FHS for more
8716 details). You must not install a pre-formatted "cat page".
8720 Each program, utility, and function should have an
8721 associated manual page included in the same package. It is
8722 suggested that all configuration files also have a manual
8723 page included as well. Manual pages for protocols and other
8724 auxiliary things are optional.
8728 If no manual page is available, this is considered as a bug
8729 and should be reported to the Debian Bug Tracking System (the
8730 maintainer of the package is allowed to write this bug report
8731 themselves, if they so desire). Do not close the bug report
8732 until a proper man page is available.<footnote>
8733 It is not very hard to write a man page. See the
8734 <url id="http://www.schweikhardt.net/man_page_howto.html"
8735 name="Man-Page-HOWTO">,
8736 <manref name="man" section="7">, the examples
8737 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8738 the helper programs <prgn>help2man</prgn>, or the
8739 directory <file>/usr/share/doc/man-db/examples</file>.
8744 You may forward a complaint about a missing man page to the
8745 upstream authors, and mark the bug as forwarded in the
8746 Debian bug tracking system. Even though the GNU Project do
8747 not in general consider the lack of a man page to be a bug,
8748 we do; if they tell you that they don't consider it a bug
8749 you should leave the bug in our bug tracking system open
8754 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8758 If one man page needs to be accessible via several names it
8759 is better to use a symbolic link than the <file>.so</file>
8760 feature, but there is no need to fiddle with the relevant
8761 parts of the upstream source to change from <file>.so</file> to
8762 symlinks: don't do it unless it's easy. You should not
8763 create hard links in the manual page directories, nor put
8764 absolute filenames in <file>.so</file> directives. The filename
8765 in a <file>.so</file> in a man page should be relative to the
8766 base of the man page tree (usually
8767 <file>/usr/share/man</file>). If you do not create any links
8768 (whether symlinks, hard links, or <tt>.so</tt> directives)
8769 in the file system to the alternate names of the man page,
8770 then you should not rely on <prgn>man</prgn> finding your
8771 man page under those names based solely on the information in
8772 the man page's header.<footnote>
8773 Supporting this in <prgn>man</prgn> often requires
8774 unreasonable processing time to find a manual page or to
8775 report that none exists, and moves knowledge into man's
8776 database that would be better left in the file system.
8777 This support is therefore deprecated and will cease to
8778 be present in the future.
8783 Manual pages in locale-specific subdirectories of
8784 <file>/usr/share/man</file> should use either UTF-8 or the usual
8785 legacy encoding for that language (normally the one corresponding
8786 to the shortest relevant locale name in
8787 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8788 <file>/usr/share/man/fr</file> should use either UTF-8 or
8789 ISO-8859-1.<footnote>
8790 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8791 use. In future, all manual pages will be required to use
8797 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8798 included in the subdirectory name unless it indicates a
8799 significant difference in the language, as this excludes
8800 speakers of the language in other countries.<footnote>
8801 At the time of writing, Chinese and Portuguese are the main
8802 languages with such differences, so <file>pt_BR</file>,
8803 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8808 Due to limitations in current implementations, all characters
8809 in the manual page source should be representable in the usual
8810 legacy encoding for that language, even if the file is
8811 actually encoded in UTF-8. Safe alternative ways to write many
8812 characters outside that range may be found in
8813 <manref name="groff_char" section="7">.
8818 <heading>Info documents</heading>
8821 Info documents should be installed in <file>/usr/share/info</file>.
8822 They should be compressed with <tt>gzip -9</tt>.
8826 Your package should call <prgn>install-info</prgn> to update
8827 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8828 script when called with a <tt>configure</tt> argument, for
8830 <example compact="compact">
8831 install-info --quiet --section Development Development \
8832 /usr/share/info/foobar.info
8836 It is a good idea to specify a section for the location of
8837 your program; this is done with the <tt>--section</tt>
8838 switch. To determine which section to use, you should look
8839 at <file>/usr/share/info/dir</file> on your system and choose the most
8840 relevant (or create a new section if none of the current
8841 sections are relevant). Note that the <tt>--section</tt>
8842 flag takes two arguments; the first is a regular expression
8843 to match (case-insensitively) against an existing section,
8844 the second is used when creating a new one.</p>
8847 You should remove the entries in the <prgn>prerm</prgn>
8848 script when called with a <tt>remove</tt> argument:
8849 <example compact="compact">
8850 install-info --quiet --remove /usr/share/info/foobar.info
8854 If <prgn>install-info</prgn> cannot find a description entry
8855 in the Info file you must supply one. See <manref
8856 name="install-info" section="8"> for details.</p>
8860 <heading>Additional documentation</heading>
8863 Any additional documentation that comes with the package may
8864 be installed at the discretion of the package maintainer.
8865 Plain text documentation should be installed in the directory
8866 <file>/usr/share/doc/<var>package</var></file>, where
8867 <var>package</var> is the name of the package, and
8868 compressed with <tt>gzip -9</tt> unless it is small.
8872 If a package comes with large amounts of documentation which
8873 many users of the package will not require you should create
8874 a separate binary package to contain it, so that it does not
8875 take up disk space on the machines of users who do not need
8876 or want it installed.</p>
8879 It is often a good idea to put text information files
8880 (<file>README</file>s, changelogs, and so forth) that come with
8881 the source package in <file>/usr/share/doc/<var>package</var></file>
8882 in the binary package. However, you don't need to install
8883 the instructions for building and installing the package, of
8887 Packages must not require the existence of any files in
8888 <file>/usr/share/doc/</file> in order to function
8890 The system administrator should be able to
8891 delete files in <file>/usr/share/doc/</file> without causing
8892 any programs to break.
8894 Any files that are referenced by programs but are also
8895 useful as stand alone documentation should be installed under
8896 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8897 <file>/usr/share/doc/<var>package</var></file>.
8901 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8902 link to another directory in <file>/usr/share/doc</file> only if
8903 the two packages both come from the same source and the
8904 first package Depends on the second.<footnote>
8906 Please note that this does not override the section on
8907 changelog files below, so the file
8908 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8909 must refer to the changelog for the current version of
8910 <var>package</var> in question. In practice, this means
8911 that the sources of the target and the destination of the
8912 symlink must be the same (same source package and
8919 Former Debian releases placed all additional documentation
8920 in <file>/usr/doc/<var>package</var></file>. This has been
8921 changed to <file>/usr/share/doc/<var>package</var></file>,
8922 and packages must not put documentation in the directory
8923 <file>/usr/doc/<var>package</var></file>. <footnote>
8924 At this phase of the transition, we no longer require a
8925 symbolic link in <file>/usr/doc/</file>. At a later point,
8926 policy shall change to make the symbolic links a bug.
8932 <heading>Preferred documentation formats</heading>
8935 The unification of Debian documentation is being carried out
8939 If your package comes with extensive documentation in a
8940 markup format that can be converted to various other formats
8941 you should if possible ship HTML versions in a binary
8942 package, in the directory
8943 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8944 its subdirectories.<footnote>
8945 The rationale: The important thing here is that HTML
8946 docs should be available in <em>some</em> package, not
8947 necessarily in the main binary package.
8952 Other formats such as PostScript may be provided at the
8953 package maintainer's discretion.
8957 <sect id="copyrightfile">
8958 <heading>Copyright information</heading>
8961 Every package must be accompanied by a verbatim copy of its
8962 copyright and distribution license in the file
8963 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8964 file must neither be compressed nor be a symbolic link.
8968 In addition, the copyright file must say where the upstream
8969 sources (if any) were obtained. It should name the original
8970 authors of the package and the Debian maintainer(s) who were
8971 involved with its creation.
8975 Packages in the <em>contrib</em> or <em>non-free</em>
8976 distribution areas should state in the copyright file that the
8977 package is not part of the Debian GNU/Linux distribution and
8978 briefly explain why.
8982 A copy of the file which will be installed in
8983 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8984 be in <file>debian/copyright</file> in the source package.
8988 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8989 link to another directory in <file>/usr/share/doc</file> only if
8990 the two packages both come from the same source and the
8991 first package Depends on the second. These rules are
8992 important because copyrights must be extractable by
8997 Packages distributed under the UCB BSD license, the Apache
8998 license (version 2.0), the Artistic license, the GNU GPL
8999 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and
9000 the GNU FDL (version 1.2) should refer to the corresponding
9001 files under <file>/usr/share/common-licenses</file>,<footnote>
9004 <file>/usr/share/common-licenses/BSD</file>,
9005 <file>/usr/share/common-licenses/Apache-2.0</file>,
9006 <file>/usr/share/common-licenses/Artistic</file>,
9007 <file>/usr/share/common-licenses/GPL-2</file>,
9008 <file>/usr/share/common-licenses/GPL-3</file>,
9009 <file>/usr/share/common-licenses/LGPL-2</file>,
9010 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9011 <file>/usr/share/common-licenses/LGPL-3</file>, and
9012 <file>/usr/share/common-licenses/GFDL-1.2</file>
9015 </footnote> rather than quoting them in the copyright
9020 You should not use the copyright file as a general <file>README</file>
9021 file. If your package has such a file it should be
9022 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9023 <file>README.Debian</file> or some other appropriate place.</p>
9027 <heading>Examples</heading>
9030 Any examples (configurations, source files, whatever),
9031 should be installed in a directory
9032 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9033 files should not be referenced by any program: they're there
9034 for the benefit of the system administrator and users as
9035 documentation only. Architecture-specific example files
9036 should be installed in a directory
9037 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9039 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9040 latter directory itself may be a symbolic link to the
9045 If the purpose of a package is to provide examples, then the
9046 example files may be installed into
9047 <file>/usr/share/doc/<var>package</var></file>.
9051 <sect id="changelogs">
9052 <heading>Changelog files</heading>
9055 Packages that are not Debian-native must contain a
9056 compressed copy of the <file>debian/changelog</file> file from
9057 the Debian source tree in
9058 <file>/usr/share/doc/<var>package</var></file> with the name
9059 <file>changelog.Debian.gz</file>.
9063 If an upstream changelog is available, it should be accessible as
9064 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9065 plain text. If the upstream changelog is distributed in
9066 HTML, it should be made available in that form as
9067 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9068 and a plain text <file>changelog.gz</file> should be generated
9069 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9070 the upstream changelog files do not already conform to this
9071 naming convention, then this may be achieved either by
9072 renaming the files, or by adding a symbolic link, at the
9073 maintainer's discretion.<footnote>
9074 Rationale: People should not have to look in places for
9075 upstream changelogs merely because they are given
9076 different names or are distributed in HTML format.
9081 All of these files should be installed compressed using
9082 <tt>gzip -9</tt>, as they will become large with time even
9083 if they start out small.
9087 If the package has only one changelog which is used both as
9088 the Debian changelog and the upstream one because there is
9089 no separate upstream maintainer then that changelog should
9090 usually be installed as
9091 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9092 there is a separate upstream maintainer, but no upstream
9093 changelog, then the Debian changelog should still be called
9094 <file>changelog.Debian.gz</file>.
9098 For details about the format and contents of the Debian
9099 changelog file, please see <ref id="dpkgchangelog">.
9104 <appendix id="pkg-scope">
9105 <heading>Introduction and scope of these appendices</heading>
9108 These appendices are taken essentially verbatim from the
9109 now-deprecated Packaging Manual, version 3.2.1.0. They are
9110 the chapters which are likely to be of use to package
9111 maintainers and which have not already been included in the
9112 policy document itself. Most of these sections are very likely
9113 not relevant to policy; they should be treated as
9114 documentation for the packaging system. Please note that these
9115 appendices are included for convenience, and for historical
9116 reasons: they used to be part of policy package, and they have
9117 not yet been incorporated into dpkg documentation. However,
9118 they still have value, and hence they are presented here.
9122 They have not yet been checked to ensure that they are
9123 compatible with the contents of policy, and if there are any
9124 contradictions, the version in the main policy document takes
9125 precedence. The remaining chapters of the old Packaging
9126 Manual have also not been read in detail to ensure that there
9127 are not parts which have been left out. Both of these will be
9132 Certain parts of the Packaging manual were integrated into the
9133 Policy Manual proper, and removed from the appendices. Links
9134 have been placed from the old locations to the new ones.
9138 <prgn>dpkg</prgn> is a suite of programs for creating binary
9139 package files and installing and removing them on Unix
9141 <prgn>dpkg</prgn> is targeted primarily at Debian
9142 GNU/Linux, but may work on or be ported to other
9148 The binary packages are designed for the management of
9149 installed executable programs (usually compiled binaries) and
9150 their associated data, though source code examples and
9151 documentation are provided as part of some packages.</p>
9154 This manual describes the technical aspects of creating Debian
9155 binary packages (<file>.deb</file> files). It documents the
9156 behavior of the package management programs
9157 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9158 they interact with packages.</p>
9161 It also documents the interaction between
9162 <prgn>dselect</prgn>'s core and the access method scripts it
9163 uses to actually install the selected packages, and describes
9164 how to create a new access method.</p>
9167 This manual does not go into detail about the options and
9168 usage of the package building and installation tools. It
9169 should therefore be read in conjunction with those programs'
9174 The utility programs which are provided with <prgn>dpkg</prgn>
9175 for managing various system configuration and similar issues,
9176 such as <prgn>update-rc.d</prgn> and
9177 <prgn>install-info</prgn>, are not described in detail here -
9178 please see their man pages.
9182 It is assumed that the reader is reasonably familiar with the
9183 <prgn>dpkg</prgn> System Administrators' manual.
9184 Unfortunately this manual does not yet exist.
9188 The Debian version of the FSF's GNU hello program is provided
9189 as an example for people wishing to create Debian
9190 packages. The Debian <prgn>debmake</prgn> package is
9191 recommended as a very helpful tool in creating and maintaining
9192 Debian packages. However, while the tools and examples are
9193 helpful, they do not replace the need to read and follow the
9194 Policy and Programmer's Manual.</p>
9197 <appendix id="pkg-binarypkg">
9198 <heading>Binary packages (from old Packaging Manual)</heading>
9201 The binary package has two main sections. The first part
9202 consists of various control information files and scripts used
9203 by <prgn>dpkg</prgn> when installing and removing. See <ref
9204 id="pkg-controlarea">.
9208 The second part is an archive containing the files and
9209 directories to be installed.
9213 In the future binary packages may also contain other
9214 components, such as checksums and digital signatures. The
9215 format for the archive is described in full in the
9216 <file>deb(5)</file> man page.
9220 <sect id="pkg-bincreating"><heading>Creating package files -
9221 <prgn>dpkg-deb</prgn>
9225 All manipulation of binary package files is done by
9226 <prgn>dpkg-deb</prgn>; it's the only program that has
9227 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9228 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9229 will spot that the options requested are appropriate to
9230 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9235 In order to create a binary package you must make a
9236 directory tree which contains all the files and directories
9237 you want to have in the file system data part of the package.
9238 In Debian-format source packages this directory is usually
9239 <file>debian/tmp</file>, relative to the top of the package's
9244 They should have the locations (relative to the root of the
9245 directory tree you're constructing) ownerships and
9246 permissions which you want them to have on the system when
9251 With current versions of <prgn>dpkg</prgn> the uid/username
9252 and gid/groupname mappings for the users and groups being
9253 used should be the same on the system where the package is
9254 built and the one where it is installed.
9258 You need to add one special directory to the root of the
9259 miniature file system tree you're creating:
9260 <prgn>DEBIAN</prgn>. It should contain the control
9261 information files, notably the binary package control file
9262 (see <ref id="pkg-controlfile">).
9266 The <prgn>DEBIAN</prgn> directory will not appear in the
9267 file system archive of the package, and so won't be installed
9268 by <prgn>dpkg</prgn> when the package is installed.
9272 When you've prepared the package, you should invoke:
9274 dpkg --build <var>directory</var>
9279 This will build the package in
9280 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9281 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9282 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9287 See the man page <manref name="dpkg-deb" section="8"> for details of how
9288 to examine the contents of this newly-created file. You may find the
9289 output of following commands enlightening:
9291 dpkg-deb --info <var>filename</var>.deb
9292 dpkg-deb --contents <var>filename</var>.deb
9293 dpkg --contents <var>filename</var>.deb
9295 To view the copyright file for a package you could use this command:
9297 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - \*/copyright | pager
9302 <sect id="pkg-controlarea">
9303 <heading>Package control information files</heading>
9306 The control information portion of a binary package is a
9307 collection of files with names known to <prgn>dpkg</prgn>.
9308 It will treat the contents of these files specially - some
9309 of them contain information used by <prgn>dpkg</prgn> when
9310 installing or removing the package; others are scripts which
9311 the package maintainer wants <prgn>dpkg</prgn> to run.
9315 It is possible to put other files in the package control
9316 area, but this is not generally a good idea (though they
9317 will largely be ignored).
9321 Here is a brief list of the control info files supported by
9322 <prgn>dpkg</prgn> and a summary of what they're used for.
9327 <tag><tt>control</tt>
9330 This is the key description file used by
9331 <prgn>dpkg</prgn>. It specifies the package's name
9332 and version, gives its description for the user,
9333 states its relationships with other packages, and so
9334 forth. See <ref id="sourcecontrolfiles"> and
9335 <ref id="binarycontrolfiles">.
9339 It is usually generated automatically from information
9340 in the source package by the
9341 <prgn>dpkg-gencontrol</prgn> program, and with
9342 assistance from <prgn>dpkg-shlibdeps</prgn>.
9343 See <ref id="pkg-sourcetools">.
9347 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9352 These are executable files (usually scripts) which
9353 <prgn>dpkg</prgn> runs during installation, upgrade
9354 and removal of packages. They allow the package to
9355 deal with matters which are particular to that package
9356 or require more complicated processing than that
9357 provided by <prgn>dpkg</prgn>. Details of when and
9358 how they are called are in <ref id="maintainerscripts">.
9362 It is very important to make these scripts idempotent.
9363 See <ref id="idempotency">.
9367 The maintainer scripts are guaranteed to run with a
9368 controlling terminal and can interact with the user.
9369 See <ref id="controllingterminal">.
9373 <tag><tt>conffiles</tt>
9376 This file contains a list of configuration files which
9377 are to be handled automatically by <prgn>dpkg</prgn>
9378 (see <ref id="pkg-conffiles">). Note that not necessarily
9379 every configuration file should be listed here.
9382 <tag><tt>shlibs</tt>
9385 This file contains a list of the shared libraries
9386 supplied by the package, with dependency details for
9387 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9388 when it determines what dependencies are required in a
9389 package control file. The <tt>shlibs</tt> file format
9390 is described on <ref id="shlibs">.
9395 <sect id="pkg-controlfile">
9396 <heading>The main control information file: <tt>control</tt></heading>
9399 The most important control information file used by
9400 <prgn>dpkg</prgn> when it installs a package is
9401 <tt>control</tt>. It contains all the package's "vital
9406 The binary package control files of packages built from
9407 Debian sources are made by a special tool,
9408 <prgn>dpkg-gencontrol</prgn>, which reads
9409 <file>debian/control</file> and <file>debian/changelog</file> to
9410 find the information it needs. See <ref id="pkg-sourcepkg"> for
9415 The fields in binary package control files are listed in
9416 <ref id="binarycontrolfiles">.
9420 A description of the syntax of control files and the purpose
9421 of the fields is available in <ref id="controlfields">.
9426 <heading>Time Stamps</heading>
9429 See <ref id="timestamps">.
9434 <appendix id="pkg-sourcepkg">
9435 <heading>Source packages (from old Packaging Manual) </heading>
9438 The Debian binary packages in the distribution are generated
9439 from Debian sources, which are in a special format to assist
9440 the easy and automatic building of binaries.
9443 <sect id="pkg-sourcetools">
9444 <heading>Tools for processing source packages</heading>
9447 Various tools are provided for manipulating source packages;
9448 they pack and unpack sources and help build of binary
9449 packages and help manage the distribution of new versions.
9453 They are introduced and typical uses described here; see
9454 <manref name="dpkg-source" section="1"> for full
9455 documentation about their arguments and operation.
9459 For examples of how to construct a Debian source package,
9460 and how to use those utilities that are used by Debian
9461 source packages, please see the <prgn>hello</prgn> example
9465 <sect1 id="pkg-dpkg-source">
9467 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9472 This program is frequently used by hand, and is also
9473 called from package-independent automated building scripts
9474 such as <prgn>dpkg-buildpackage</prgn>.
9478 To unpack a package it is typically invoked with
9480 dpkg-source -x <var>.../path/to/filename</var>.dsc
9485 with the <file><var>filename</var>.tar.gz</file> and
9486 <file><var>filename</var>.diff.gz</file> (if applicable) in
9487 the same directory. It unpacks into
9488 <file><var>package</var>-<var>version</var></file>, and if
9490 <file><var>package</var>-<var>version</var>.orig</file>, in
9491 the current directory.
9495 To create a packed source archive it is typically invoked:
9497 dpkg-source -b <var>package</var>-<var>version</var>
9502 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9503 <file>.diff.gz</file> (if appropriate) in the current
9504 directory. <prgn>dpkg-source</prgn> does not clean the
9505 source tree first - this must be done separately if it is
9510 See also <ref id="pkg-sourcearchives">.</p>
9514 <sect1 id="pkg-dpkg-buildpackage">
9516 <prgn>dpkg-buildpackage</prgn> - overall package-building
9521 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9522 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9523 targets <tt>clean</tt>, <tt>build</tt> and
9524 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9525 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9526 source and binary package upload.
9530 It is usually invoked by hand from the top level of the
9531 built or unbuilt source directory. It may be invoked with
9532 no arguments; useful arguments include:
9533 <taglist compact="compact">
9534 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9537 Do not sign the <tt>.changes</tt> file or the
9538 source package <tt>.dsc</tt> file, respectively.</p>
9540 <tag><tt>-p<var>sign-command</var></tt></tag>
9543 Invoke <var>sign-command</var> instead of finding
9544 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9545 <var>sign-command</var> must behave just like
9546 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9548 <tag><tt>-r<var>root-command</var></tt></tag>
9551 When root privilege is required, invoke the command
9552 <var>root-command</var>. <var>root-command</var>
9553 should invoke its first argument as a command, from
9554 the <prgn>PATH</prgn> if necessary, and pass its
9555 second and subsequent arguments to the command it
9556 calls. If no <var>root-command</var> is supplied
9557 then <var>dpkg-buildpackage</var> will take no
9558 special action to gain root privilege, so that for
9559 most packages it will have to be invoked as root to
9562 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9565 Two types of binary-only build and upload - see
9566 <manref name="dpkg-source" section="1">.
9573 <sect1 id="pkg-dpkg-gencontrol">
9575 <prgn>dpkg-gencontrol</prgn> - generates binary package
9580 This program is usually called from <file>debian/rules</file>
9581 (see <ref id="pkg-sourcetree">) in the top level of the source
9586 This is usually done just before the files and directories in the
9587 temporary directory tree where the package is being built have their
9588 permissions and ownerships set and the package is constructed using
9589 <prgn>dpkg-deb/</prgn>
9591 This is so that the control file which is produced has
9592 the right permissions
9597 <prgn>dpkg-gencontrol</prgn> must be called after all the
9598 files which are to go into the package have been placed in
9599 the temporary build directory, so that its calculation of
9600 the installed size of a package is correct.
9604 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9605 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9606 variable substitutions created by
9607 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9612 For a package which generates only one binary package, and
9613 which builds it in <file>debian/tmp</file> relative to the top
9614 of the source package, it is usually sufficient to call
9615 <prgn>dpkg-gencontrol</prgn>.
9619 Sources which build several binaries will typically need
9622 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9623 </example> The <tt>-P</tt> tells
9624 <prgn>dpkg-gencontrol</prgn> that the package is being
9625 built in a non-default directory, and the <tt>-p</tt>
9626 tells it which package's control file should be generated.
9630 <prgn>dpkg-gencontrol</prgn> also adds information to the
9631 list of files in <file>debian/files</file>, for the benefit of
9632 (for example) a future invocation of
9633 <prgn>dpkg-genchanges</prgn>.</p>
9636 <sect1 id="pkg-dpkg-shlibdeps">
9638 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9643 This program is usually called from <file>debian/rules</file>
9644 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9645 id="pkg-sourcetree">), in the top level of the source tree.
9649 Its arguments are executables and shared libraries
9652 They may be specified either in the locations in the
9653 source tree where they are created or in the locations
9654 in the temporary build tree where they are installed
9655 prior to binary package creation.
9657 </footnote> for which shared library dependencies should
9658 be included in the binary package's control file.
9662 If some of the found shared libraries should only
9663 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9664 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9665 by using the <tt>-d<var>dependency-field</var></tt> option
9666 before those executable(s). (Each <tt>-d</tt> option
9667 takes effect until the next <tt>-d</tt>.)
9671 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9672 output control file to be modified. Instead by default it
9673 adds to the <file>debian/substvars</file> file variable
9674 settings like <tt>shlibs:Depends</tt>. These variable
9675 settings must be referenced in dependency fields in the
9676 appropriate per-binary-package sections of the source
9681 For example, a package that generates an essential part
9682 which requires dependencies, and optional parts that
9683 which only require a recommendation, would separate those
9684 two sets of dependencies into two different fields.<footnote>
9685 At the time of writing, an example for this was the
9686 <package/xmms/ package, with Depends used for the xmms
9687 executable, Recommends for the plug-ins and Suggests for
9688 even more optional features provided by unzip.
9690 It can say in its <file>debian/rules</file>:
9692 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9693 -dRecommends <var>optionalpart anotheroptionalpart</var>
9695 and then in its main control file <file>debian/control</file>:
9698 Depends: ${shlibs:Depends}
9699 Recommends: ${shlibs:Recommends}
9705 Sources which produce several binary packages with
9706 different shared library dependency requirements can use
9707 the <tt>-p<var>varnameprefix</var></tt> option to override
9708 the default <tt>shlibs:</tt> prefix (one invocation of
9709 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9710 They can thus produce several sets of dependency
9711 variables, each of the form
9712 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9713 which can be referred to in the appropriate parts of the
9714 binary package control files.
9719 <sect1 id="pkg-dpkg-distaddfile">
9721 <prgn>dpkg-distaddfile</prgn> - adds a file to
9722 <file>debian/files</file>
9726 Some packages' uploads need to include files other than
9727 the source and binary package files.
9731 <prgn>dpkg-distaddfile</prgn> adds a file to the
9732 <file>debian/files</file> file so that it will be included in
9733 the <file>.changes</file> file when
9734 <prgn>dpkg-genchanges</prgn> is run.
9738 It is usually invoked from the <tt>binary</tt> target of
9739 <file>debian/rules</file>:
9741 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9743 The <var>filename</var> is relative to the directory where
9744 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9745 is usually the directory above the top level of the source
9746 tree. The <file>debian/rules</file> target should put the
9747 file there just before or just after calling
9748 <prgn>dpkg-distaddfile</prgn>.
9752 The <var>section</var> and <var>priority</var> are passed
9753 unchanged into the resulting <file>.changes</file> file.
9758 <sect1 id="pkg-dpkg-genchanges">
9760 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9765 This program is usually called by package-independent
9766 automatic building scripts such as
9767 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9772 It is usually called in the top level of a built source
9773 tree, and when invoked with no arguments will print out a
9774 straightforward <file>.changes</file> file based on the
9775 information in the source package's changelog and control
9776 file and the binary and source packages which should have
9782 <sect1 id="pkg-dpkg-parsechangelog">
9784 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9785 representation of a changelog
9789 This program is used internally by
9790 <prgn>dpkg-source</prgn> et al. It may also occasionally
9791 be useful in <file>debian/rules</file> and elsewhere. It
9792 parses a changelog, <file>debian/changelog</file> by default,
9793 and prints a control-file format representation of the
9794 information in it to standard output.
9798 <sect1 id="pkg-dpkg-architecture">
9800 <prgn>dpkg-architecture</prgn> - information about the build and
9805 This program can be used manually, but is also invoked by
9806 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9807 environment or make variables which specify the build and host
9808 architecture for the package building process.
9813 <sect id="pkg-sourcetree">
9814 <heading>The Debianised source tree</heading>
9817 The source archive scheme described later is intended to
9818 allow a Debianised source tree with some associated control
9819 information to be reproduced and transported easily. The
9820 Debianised source tree is a version of the original program
9821 with certain files added for the benefit of the
9822 Debianisation process, and with any other changes required
9823 made to the rest of the source code and installation
9828 The extra files created for Debian are in the subdirectory
9829 <file>debian</file> of the top level of the Debianised source
9830 tree. They are described below.
9833 <sect1 id="pkg-debianrules">
9834 <heading><file>debian/rules</file> - the main building script</heading>
9837 See <ref id="debianrules">.
9842 <sect1 id="pkg-dpkgchangelog">
9843 <heading><file>debian/changelog</file></heading>
9846 See <ref id="dpkgchangelog">.
9849 <sect2><heading>Defining alternative changelog formats
9853 It is possible to use a different format to the standard
9854 one, by providing a parser for the format you wish to
9859 In order to have <tt>dpkg-parsechangelog</tt> run your
9860 parser, you must include a line within the last 40 lines
9861 of your file matching the Perl regular expression:
9862 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9863 parentheses should be the name of the format. For
9864 example, you might say:
9866 @@@ changelog-format: joebloggs @@@
9868 Changelog format names are non-empty strings of alphanumerics.
9872 If such a line exists then <tt>dpkg-parsechangelog</tt>
9873 will look for the parser as
9874 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9876 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9877 it is an error for it not to find it, or for it not to
9878 be an executable program. The default changelog format
9879 is <tt>dpkg</tt>, and a parser for it is provided with
9880 the <tt>dpkg</tt> package.
9884 The parser will be invoked with the changelog open on
9885 standard input at the start of the file. It should read
9886 the file (it may seek if it wishes) to determine the
9887 information required and return the parsed information
9888 to standard output in the form of a series of control
9889 fields in the standard format. By default it should
9890 return information about only the most recent version in
9891 the changelog; it should accept a
9892 <tt>-v<var>version</var></tt> option to return changes
9893 information from all versions present <em>strictly
9894 after</em> <var>version</var>, and it should then be an
9895 error for <var>version</var> not to be present in the
9901 <list compact="compact">
9902 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9903 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9904 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9905 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9906 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9907 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9908 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9913 If several versions are being returned (due to the use
9914 of <tt>-v</tt>), the urgency value should be of the
9915 highest urgency code listed at the start of any of the
9916 versions requested followed by the concatenated
9917 (space-separated) comments from all the versions
9918 requested; the maintainer, version, distribution and
9919 date should always be from the most recent version.
9923 For the format of the <tt>Changes</tt> field see
9924 <ref id="f-Changes">.
9928 If the changelog format which is being parsed always or
9929 almost always leaves a blank line between individual
9930 change notes these blank lines should be stripped out,
9931 so as to make the resulting output compact.
9935 If the changelog format does not contain date or package
9936 name information this information should be omitted from
9937 the output. The parser should not attempt to synthesize
9938 it or find it from other sources.
9942 If the changelog does not have the expected format the
9943 parser should exit with a nonzero exit status, rather
9944 than trying to muddle through and possibly generating
9949 A changelog parser may not interact with the user at
9955 <sect1 id="pkg-srcsubstvars">
9956 <heading><file>debian/substvars</file> and variable substitutions</heading>
9959 See <ref id="substvars">.
9965 <heading><file>debian/files</file></heading>
9968 See <ref id="debianfiles">.
9972 <sect1><heading><file>debian/tmp</file>
9976 This is the canonical temporary location for the
9977 construction of binary packages by the <tt>binary</tt>
9978 target. The directory <file>tmp</file> serves as the root of
9979 the file system tree as it is being constructed (for
9980 example, by using the package's upstream makefiles install
9981 targets and redirecting the output there), and it also
9982 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9983 id="pkg-bincreating">.
9987 If several binary packages are generated from the same
9988 source tree it is usual to use several
9989 <file>debian/tmp<var>something</var></file> directories, for
9990 example <file>tmp-a</file> or <file>tmp-doc</file>.
9994 Whatever <file>tmp</file> directories are created and used by
9995 <tt>binary</tt> must of course be removed by the
9996 <tt>clean</tt> target.</p></sect1>
10000 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10004 As it exists on the FTP site, a Debian source package
10005 consists of three related files. You must have the right
10006 versions of all three to be able to use them.
10011 <tag>Debian source control file - <tt>.dsc</tt></tag>
10013 This file is a control file used by <prgn>dpkg-source</prgn>
10014 to extract a source package.
10015 See <ref id="debiansourcecontrolfiles">.
10019 Original source archive -
10021 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10027 This is a compressed (with <tt>gzip -9</tt>)
10028 <prgn>tar</prgn> file containing the source code from
10029 the upstream authors of the program.
10034 Debianisation diff -
10036 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10042 This is a unified context diff (<tt>diff -u</tt>)
10043 giving the changes which are required to turn the
10044 original source into the Debian source. These changes
10045 may only include editing and creating plain files.
10046 The permissions of files, the targets of symbolic
10047 links and the characteristics of special files or
10048 pipes may not be changed and no files may be removed
10053 All the directories in the diff must exist, except the
10054 <file>debian</file> subdirectory of the top of the source
10055 tree, which will be created by
10056 <prgn>dpkg-source</prgn> if necessary when unpacking.
10060 The <prgn>dpkg-source</prgn> program will
10061 automatically make the <file>debian/rules</file> file
10062 executable (see below).</p></item>
10067 If there is no original source code - for example, if the
10068 package is specially prepared for Debian or the Debian
10069 maintainer is the same as the upstream maintainer - the
10070 format is slightly different: then there is no diff, and the
10072 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10073 and preferably contains a directory named
10074 <file><var>package</var>-<var>version</var></file>.
10079 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10082 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10083 Debian source package. However, if it is not available it
10084 is possible to unpack a Debian source archive as follows:
10085 <enumlist compact="compact">
10088 Untar the tarfile, which will create a <file>.orig</file>
10092 <p>Rename the <file>.orig</file> directory to
10093 <file><var>package</var>-<var>version</var></file>.</p>
10097 Create the subdirectory <file>debian</file> at the top of
10098 the source tree.</p>
10100 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10102 <item><p>Untar the tarfile again if you want a copy of the original
10103 source code alongside the Debianised version.</p>
10108 It is not possible to generate a valid Debian source archive
10109 without using <prgn>dpkg-source</prgn>. In particular,
10110 attempting to use <prgn>diff</prgn> directly to generate the
10111 <file>.diff.gz</file> file will not work.
10115 <heading>Restrictions on objects in source packages</heading>
10118 The source package may not contain any hard links
10120 This is not currently detected when building source
10121 packages, but only when extracting
10125 Hard links may be permitted at some point in the
10126 future, but would require a fair amount of
10128 </footnote>, device special files, sockets or setuid or
10131 Setgid directories are allowed.
10136 The source packaging tools manage the changes between the
10137 original and Debianised source using <prgn>diff</prgn> and
10138 <prgn>patch</prgn>. Turning the original source tree as
10139 included in the <file>.orig.tar.gz</file> into the debianised
10140 source must not involve any changes which cannot be
10141 handled by these tools. Problematic changes which cause
10142 <prgn>dpkg-source</prgn> to halt with an error when
10143 building the source package are:
10144 <list compact="compact">
10145 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10147 <item><p>Changing the targets of symbolic links.</p>
10149 <item><p>Creating directories, other than <file>debian</file>.</p>
10151 <item><p>Changes to the contents of binary files.</p></item>
10152 </list> Changes which cause <prgn>dpkg-source</prgn> to
10153 print a warning but continue anyway are:
10154 <list compact="compact">
10157 Removing files, directories or symlinks.
10159 Renaming a file is not treated specially - it is
10160 seen as the removal of the old file (which
10161 generates a warning, but is otherwise ignored),
10162 and the creation of the new one.
10168 Changed text files which are missing the usual final
10169 newline (either in the original or the modified
10174 Changes which are not represented, but which are not detected by
10175 <prgn>dpkg-source</prgn>, are:
10176 <list compact="compact">
10177 <item><p>Changing the permissions of files (other than
10178 <file>debian/rules</file>) and directories.</p></item>
10183 The <file>debian</file> directory and <file>debian/rules</file>
10184 are handled specially by <prgn>dpkg-source</prgn> - before
10185 applying the changes it will create the <file>debian</file>
10186 directory, and afterwards it will make
10187 <file>debian/rules</file> world-executable.
10193 <appendix id="pkg-controlfields">
10194 <heading>Control files and their fields (from old Packaging Manual)</heading>
10197 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10198 data in a common format, known as control files. Binary and
10199 source packages have control data as do the <file>.changes</file>
10200 files which control the installation of uploaded files, and
10201 <prgn>dpkg</prgn>'s internal databases are in a similar
10206 <heading>Syntax of control files</heading>
10209 See <ref id="controlsyntax">.
10213 It is important to note that there are several fields which
10214 are optional as far as <prgn>dpkg</prgn> and the related
10215 tools are concerned, but which must appear in every Debian
10216 package, or whose omission may cause problems.
10221 <heading>List of fields</heading>
10224 See <ref id="controlfieldslist">.
10228 This section now contains only the fields that didn't belong
10229 to the Policy manual.
10232 <sect1 id="pkg-f-Filename">
10233 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10236 These fields in <tt>Packages</tt> files give the
10237 filename(s) of (the parts of) a package in the
10238 distribution directories, relative to the root of the
10239 Debian hierarchy. If the package has been split into
10240 several parts the parts are all listed in order, separated
10245 <sect1 id="pkg-f-Size">
10246 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10249 These fields in <file>Packages</file> files give the size (in
10250 bytes, expressed in decimal) and MD5 checksum of the
10251 file(s) which make(s) up a binary package in the
10252 distribution. If the package is split into several parts
10253 the values for the parts are listed in order, separated by
10258 <sect1 id="pkg-f-Status">
10259 <heading><tt>Status</tt></heading>
10262 This field in <prgn>dpkg</prgn>'s status file records
10263 whether the user wants a package installed, removed or
10264 left alone, whether it is broken (requiring
10265 re-installation) or not and what its current state on the
10266 system is. Each of these pieces of information is a
10271 <sect1 id="pkg-f-Config-Version">
10272 <heading><tt>Config-Version</tt></heading>
10275 If a package is not installed or not configured, this
10276 field in <prgn>dpkg</prgn>'s status file records the last
10277 version of the package which was successfully
10282 <sect1 id="pkg-f-Conffiles">
10283 <heading><tt>Conffiles</tt></heading>
10286 This field in <prgn>dpkg</prgn>'s status file contains
10287 information about the automatically-managed configuration
10288 files held by a package. This field should <em>not</em>
10289 appear anywhere in a package!
10294 <heading>Obsolete fields</heading>
10297 These are still recognized by <prgn>dpkg</prgn> but should
10298 not appear anywhere any more.
10300 <taglist compact="compact">
10302 <tag><tt>Revision</tt></tag>
10303 <tag><tt>Package-Revision</tt></tag>
10304 <tag><tt>Package_Revision</tt></tag>
10306 The Debian revision part of the package version was
10307 at one point in a separate control file field. This
10308 field went through several names.
10311 <tag><tt>Recommended</tt></tag>
10312 <item>Old name for <tt>Recommends</tt>.</item>
10314 <tag><tt>Optional</tt></tag>
10315 <item>Old name for <tt>Suggests</tt>.</item>
10317 <tag><tt>Class</tt></tag>
10318 <item>Old name for <tt>Priority</tt>.</item>
10327 <appendix id="pkg-conffiles">
10328 <heading>Configuration file handling (from old Packaging Manual)</heading>
10331 <prgn>dpkg</prgn> can do a certain amount of automatic
10332 handling of package configuration files.
10336 Whether this mechanism is appropriate depends on a number of
10337 factors, but basically there are two approaches to any
10338 particular configuration file.
10342 The easy method is to ship a best-effort configuration in the
10343 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10344 handle updates. If the user is unlikely to want to edit the
10345 file, but you need them to be able to without losing their
10346 changes, and a new package with a changed version of the file
10347 is only released infrequently, this is a good approach.
10351 The hard method is to build the configuration file from
10352 scratch in the <prgn>postinst</prgn> script, and to take the
10353 responsibility for fixing any mistakes made in earlier
10354 versions of the package automatically. This will be
10355 appropriate if the file is likely to need to be different on
10359 <sect><heading>Automatic handling of configuration files by
10364 A package may contain a control area file called
10365 <tt>conffiles</tt>. This file should be a list of filenames
10366 of configuration files needing automatic handling, separated
10367 by newlines. The filenames should be absolute pathnames,
10368 and the files referred to should actually exist in the
10373 When a package is upgraded <prgn>dpkg</prgn> will process
10374 the configuration files during the configuration stage,
10375 shortly before it runs the package's <prgn>postinst</prgn>
10380 For each file it checks to see whether the version of the
10381 file included in the package is the same as the one that was
10382 included in the last version of the package (the one that is
10383 being upgraded from); it also compares the version currently
10384 installed on the system with the one shipped with the last
10389 If neither the user nor the package maintainer has changed
10390 the file, it is left alone. If one or the other has changed
10391 their version, then the changed version is preferred - i.e.,
10392 if the user edits their file, but the package maintainer
10393 doesn't ship a different version, the user's changes will
10394 stay, silently, but if the maintainer ships a new version
10395 and the user hasn't edited it the new version will be
10396 installed (with an informative message). If both have
10397 changed their version the user is prompted about the problem
10398 and must resolve the differences themselves.
10402 The comparisons are done by calculating the MD5 message
10403 digests of the files, and storing the MD5 of the file as it
10404 was included in the most recent version of the package.
10408 When a package is installed for the first time
10409 <prgn>dpkg</prgn> will install the file that comes with it,
10410 unless that would mean overwriting a file already on the
10415 However, note that <prgn>dpkg</prgn> will <em>not</em>
10416 replace a conffile that was removed by the user (or by a
10417 script). This is necessary because with some programs a
10418 missing file produces an effect hard or impossible to
10419 achieve in another way, so that a missing file needs to be
10420 kept that way if the user did it.
10424 Note that a package should <em>not</em> modify a
10425 <prgn>dpkg</prgn>-handled conffile in its maintainer
10426 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10427 the user confusing and possibly dangerous options for
10428 conffile update when the package is upgraded.</p>
10431 <sect><heading>Fully-featured maintainer script configuration
10436 For files which contain site-specific information such as
10437 the hostname and networking details and so forth, it is
10438 better to create the file in the package's
10439 <prgn>postinst</prgn> script.
10443 This will typically involve examining the state of the rest
10444 of the system to determine values and other information, and
10445 may involve prompting the user for some information which
10446 can't be obtained some other way.
10450 When using this method there are a couple of important
10451 issues which should be considered:
10455 If you discover a bug in the program which generates the
10456 configuration file, or if the format of the file changes
10457 from one version to the next, you will have to arrange for
10458 the postinst script to do something sensible - usually this
10459 will mean editing the installed configuration file to remove
10460 the problem or change the syntax. You will have to do this
10461 very carefully, since the user may have changed the file,
10462 perhaps to fix the very problem that your script is trying
10463 to deal with - you will have to detect these situations and
10464 deal with them correctly.
10468 If you do go down this route it's probably a good idea to
10469 make the program that generates the configuration file(s) a
10470 separate program in <file>/usr/sbin</file>, by convention called
10471 <file><var>package</var>config</file> and then run that if
10472 appropriate from the post-installation script. The
10473 <tt><var>package</var>config</tt> program should not
10474 unquestioningly overwrite an existing configuration - if its
10475 mode of operation is geared towards setting up a package for
10476 the first time (rather than any arbitrary reconfiguration
10477 later) you should have it check whether the configuration
10478 already exists, and require a <tt>--force</tt> flag to
10479 overwrite it.</p></sect>
10482 <appendix id="pkg-alternatives"><heading>Alternative versions of
10483 an interface - <prgn>update-alternatives</prgn> (from old
10488 When several packages all provide different versions of the
10489 same program or file it is useful to have the system select a
10490 default, but to allow the system administrator to change it
10491 and have their decisions respected.
10495 For example, there are several versions of the <prgn>vi</prgn>
10496 editor, and there is no reason to prevent all of them from
10497 being installed at once, each under their own name
10498 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10499 Nevertheless it is desirable to have the name <tt>vi</tt>
10500 refer to something, at least by default.
10504 If all the packages involved cooperate, this can be done with
10505 <prgn>update-alternatives</prgn>.
10509 Each package provides its own version under its own name, and
10510 calls <prgn>update-alternatives</prgn> in its postinst to
10511 register its version (and again in its prerm to deregister
10516 See the man page <manref name="update-alternatives"
10517 section="8"> for details.
10521 If <prgn>update-alternatives</prgn> does not seem appropriate
10522 you may wish to consider using diversions instead.</p>
10525 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10526 package's version of a file (from old Packaging Manual)
10530 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10531 when it reinstalls the package it belongs to, and to have it
10532 put the file from the package somewhere else instead.
10536 This can be used locally to override a package's version of a
10537 file, or by one package to override another's version (or
10538 provide a wrapper for it).
10542 Before deciding to use a diversion, read <ref
10543 id="pkg-alternatives"> to see if you really want a diversion
10544 rather than several alternative versions of a program.
10548 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10549 and updated by a special program <prgn>dpkg-divert</prgn>.
10550 Please see <manref name="dpkg-divert" section="8"> for full
10551 details of its operation.
10555 When a package wishes to divert a file from another, it should
10556 call <prgn>dpkg-divert</prgn> in its preinst to add the
10557 diversion and rename the existing file. For example,
10558 supposing that a <prgn>smailwrapper</prgn> package wishes to
10559 install a wrapper around <file>/usr/sbin/smail</file>:
10561 dpkg-divert --package smailwrapper --add --rename \
10562 --divert /usr/sbin/smail.real /usr/sbin/smail
10563 </example> The <tt>--package smailwrapper</tt> ensures that
10564 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10565 can bypass the diversion and get installed as the true version.
10566 It's safe to add the diversion unconditionally on upgrades since
10567 it will be left unchanged if it already exists, but
10568 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10569 message, make the command conditional on the version from which
10570 the package is being upgraded:
10572 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10573 dpkg-divert --package smailwrapper --add --rename \
10574 --divert /usr/sbin/smail.real /usr/sbin/smail
10576 </example> where <tt>1.0-2</tt> is the version at which the
10577 diversion was first added to the package. Running the command
10578 during abort-upgrade is pointless but harmless.
10582 The postrm has to do the reverse:
10584 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10585 dpkg-divert --package smailwrapper --remove --rename \
10586 --divert /usr/sbin/smail.real /usr/sbin/smail
10588 </example> If the diversion was added at a particular version, the
10589 postrm should also handle the failure case of upgrading from an
10590 older version (unless the older version is so old that direct
10591 upgrades are no longer supported):
10593 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10594 dpkg-divert --package smailwrapper --remove --rename \
10595 --divert /usr/sbin/smail.real /usr/sbin/smail
10597 </example> where <tt>1.02-2</tt> is the version at which the
10598 diversion was first added to the package. The postrm should not
10599 remove the diversion on upgrades both because there's no reason to
10600 remove the diversion only to immediately re-add it and since the
10601 postrm of the old package is run after unpacking so the removal of
10602 the diversion will fail.
10606 Do not attempt to divert a file which is vitally important for
10607 the system's operation - when using <prgn>dpkg-divert</prgn>
10608 there is a time, after it has been diverted but before
10609 <prgn>dpkg</prgn> has installed the new version, when the file
10610 does not exist.</p>
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