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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
76 Informally, the criteria used for inclusion is that the
77 material meet one of the following requirements:
78 <taglist compact="compact">
79 <tag>Standard interfaces</tag>
81 The material presented represents an interface to
82 the packaging system that is mandated for use, and
83 is used by, a significant number of packages, and
84 therefore should not be changed without peer
85 review. Package maintainers can then rely on this
86 interfaces not changing, and the package
87 management software authors need to ensure
88 compatibility with these interface
89 definitions. (Control file and changelog file
90 formats are examples.)
92 <tag>Chosen Convention</tag>
94 If there are a number of technically viable choices
95 that can be made, but one needs to select one of
96 these options for inter-operability. The version
97 number format is one example.
100 Please note that these are not mutually exclusive;
101 selected conventions often become parts of standard
107 The footnotes present in this manual are
108 merely informative, and are not part of Debian policy itself.
112 The appendices to this manual are not necessarily normative,
113 either. Please see <ref id="pkg-scope"> for more information.
117 In the normative part of this manual,
118 the words <em>must</em>, <em>should</em> and
119 <em>may</em>, and the adjectives <em>required</em>,
120 <em>recommended</em> and <em>optional</em>, are used to
121 distinguish the significance of the various guidelines in
122 this policy document. Packages that do not conform to the
123 guidelines denoted by <em>must</em> (or <em>required</em>)
124 will generally not be considered acceptable for the Debian
125 distribution. Non-conformance with guidelines denoted by
126 <em>should</em> (or <em>recommended</em>) will generally be
127 considered a bug, but will not necessarily render a package
128 unsuitable for distribution. Guidelines denoted by
129 <em>may</em> (or <em>optional</em>) are truly optional and
130 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
142 Compare RFC 2119. Note, however, that these words are
143 used in a different way in this document.
148 Much of the information presented in this manual will be
149 useful even when building a package which is to be
150 distributed in some other way or is intended for local use
156 <heading>New versions of this document</heading>
159 This manual is distributed via the Debian package
160 <package>debian-policy</package>.
164 The current version of this document is also available from
165 the Debian web mirrors at
166 <tt><url name="/doc/debian-policy/"
167 id="http://www.debian.org/doc/debian-policy/"></tt>
168 and from the Debian archive mirrors at
169 <tt><url name="/doc/package-developer/policy.txt.gz"
170 id="http://ftp.debian.org/debian/doc/package-developer/policy.txt.gz"></tt>.
171 Also available from the same directory are several other
172 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
173 and <file>policy.ps.gz</file>.
177 The <package>debian-policy</package> package also includes the file
178 <file>upgrading-checklist.txt</file> which indicates policy
179 changes between versions of this document.
184 <heading>Authors and Maintainers</heading>
187 Originally called "Debian GNU/Linux Policy Manual", this
188 manual was initially written in 1996 by Ian Jackson.
189 It was revised on November 27th, 1996 by David A. Morris.
190 Christian Schwarz added new sections on March 15th, 1997,
191 and reworked/restructured it in April-July 1997.
192 Christoph Lameter contributed the "Web Standard".
193 Julian Gilbey largely restructured it in 2001.
197 Since September 1998, the responsibility for the contents of
198 this document lies on the <url name="debian-policy mailing list"
199 id="mailto:debian-policy@lists.debian.org">. Proposals
200 are discussed there and inserted into policy after a certain
201 consensus is established.
202 <!-- insert shameless policy-process plug here eventually -->
203 The actual editing is done by a group of maintainers that have
204 no editorial powers. These are the current maintainers:
207 <item>Julian Gilbey</item>
208 <item>Branden Robinson</item>
209 <item>Josip Rodin</item>
210 <item>Manoj Srivastava</item>
215 While the authors of this document have tried hard to avoid
216 typos and other errors, these do still occur. If you discover
217 an error in this manual or if you want to give any
218 comments, suggestions, or criticisms please send an email to
219 the Debian Policy List,
220 <email>debian-policy@lists.debian.org</email>, or submit a
221 bug report against the <tt>debian-policy</tt> package.
225 Please do not try to reach the individual authors or maintainers
226 of the Policy Manual regarding changes to the Policy.
231 <heading>Related documents</heading>
234 There are several other documents other than this Policy Manual
235 that are necessary to fully understand some Debian policies and
240 The external "sub-policy" documents are referred to in:
241 <list compact="compact">
242 <item><ref id="fhs"></item>
243 <item><ref id="virtual_pkg"></item>
244 <item><ref id="menus"></item>
245 <item><ref id="mime"></item>
246 <item><ref id="perl"></item>
247 <item><ref id="maintscriptprompt"></item>
248 <item><ref id="emacs"></item>
253 In addition to those, which carry the weight of policy, there
254 is the Debian Developer's Reference. This document describes
255 procedures and resources for Debian developers, but it is
256 <em>not</em> normative; rather, it includes things that don't
257 belong into the Policy, such as best practices for developers.
261 The Developer's Reference is available in the
262 <package>developers-reference</package> package.
263 It's also available from the Debian web mirrors at
264 <tt><url name="/doc/developers-reference/"
265 id="http://www.debian.org/doc/developers-reference/"></tt>.
273 <heading>The Debian Archive</heading>
276 The Debian GNU/Linux system is maintained and distributed as a
277 collection of <em>packages</em>. Since there are so many of
278 them (currently well over 6000), they are split into
279 <em>sections</em> and given <em>priorities</em> to simplify
280 the handling of them.
284 The effort of the Debian project is to build a free operating
285 system, but not every package we want to make accessible is
286 <em>free</em> in our sense (see the Debian Free Software
287 Guidelines, below), or may be imported/exported without
288 restrictions. Thus, the archive is split into the sections
289 based on their licenses and other restrictions.
293 The aims of this are:
295 <list compact="compact">
296 <item>to allow us to make as much software available as we can</item>
297 <item>to allow us to encourage everyone to write free software,
299 <item>to allow us to make it easy for people to produce
300 CD-ROMs of our system without violating any licenses,
301 import/export restrictions, or any other laws.</item>
306 The <em>main</em> and the <em>non-US/main</em> sections
307 together form the <em>Debian GNU/Linux distribution</em>.
311 Packages in the other sections are not considered to be part
312 of the Debian distribution, although we support their use and
313 provide infrastructure for them (such as our bug-tracking
314 system and mailing lists). This Debian Policy Manual applies
315 to these packages as well.
319 <heading>The Debian Free Software Guidelines</heading>
321 The Debian Free Software Guidelines (DFSG) form our
322 definition of "free software". These are:
324 <tag>Free Redistribution
327 The license of a Debian component may not restrict any
328 party from selling or giving away the software as a
329 component of an aggregate software distribution
330 containing programs from several different
331 sources. The license may not require a royalty or
332 other fee for such sale.
337 The program must include source code, and must allow
338 distribution in source code as well as compiled form.
343 The license must allow modifications and derived
344 works, and must allow them to be distributed under the
345 same terms as the license of the original software.
347 <tag>Integrity of The Author's Source Code
350 The license may restrict source-code from being
351 distributed in modified form <em>only</em> if the
352 license allows the distribution of "patch files"
353 with the source code for the purpose of modifying the
354 program at build time. The license must explicitly
355 permit distribution of software built from modified
356 source code. The license may require derived works to
357 carry a different name or version number from the
358 original software. (This is a compromise. The Debian
359 Project encourages all authors to not restrict any
360 files, source or binary, from being modified.)
362 <tag>No Discrimination Against Persons or Groups
365 The license must not discriminate against any person
368 <tag>No Discrimination Against Fields of Endeavor
371 The license must not restrict anyone from making use
372 of the program in a specific field of endeavor. For
373 example, it may not restrict the program from being
374 used in a business, or from being used for genetic
377 <tag>Distribution of License
380 The rights attached to the program must apply to all
381 to whom the program is redistributed without the need
382 for execution of an additional license by those
385 <tag>License Must Not Be Specific to Debian
388 The rights attached to the program must not depend on
389 the program's being part of a Debian system. If the
390 program is extracted from Debian and used or
391 distributed without Debian but otherwise within the
392 terms of the program's license, all parties to whom
393 the program is redistributed must have the same
394 rights as those that are granted in conjunction with
397 <tag>License Must Not Contaminate Other Software
400 The license must not place restrictions on other
401 software that is distributed along with the licensed
402 software. For example, the license must not insist
403 that all other programs distributed on the same medium
404 must be free software.
406 <tag>Example Licenses
409 The "GPL," "BSD," and "Artistic" licenses are examples of
410 licenses that we consider <em>free</em>.
417 <heading>Sections</heading>
420 <heading>The main section</heading>
423 Every package in <em>main</em> and <em>non-US/main</em>
424 must comply with the DFSG (Debian Free Software
429 In addition, the packages in <em>main</em>
430 <list compact="compact">
432 must not require a package outside of <em>main</em>
433 for compilation or execution (thus, the package must
434 not declare a "Depends", "Recommends", or
435 "Build-Depends" relationship on a non-<em>main</em>
439 must not be so buggy that we refuse to support them,
443 must meet all policy requirements presented in this
450 Similarly, the packages in <em>non-US/main</em>
451 <list compact="compact">
453 must not require a package outside of <em>main</em>
454 or <em>non-US/main</em> for compilation or
458 must not be so buggy that we refuse to support them,
461 must meet all policy requirements presented in this
470 <heading>The contrib section</heading>
473 Every package in <em>contrib</em> and
474 <em>non-US/contrib</em> must comply with the DFSG.
478 In addition, the packages in <em>contrib</em> and
479 <em>non-US/contrib</em>
480 <list compact="compact">
482 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
493 Furthermore, packages in <em>contrib</em> must not require
494 a package in a <em>non-US</em> section for compilation or
499 Examples of packages which would be included in
500 <em>contrib</em> or <em>non-US/contrib</em> are:
501 <list compact="compact">
503 free packages which require <em>contrib</em>,
504 <em>non-free</em> packages or packages which are not
505 in our archive at all for compilation or execution,
509 wrapper packages or other sorts of free accessories for
516 <sect1 id="non-free">
517 <heading>The non-free section</heading>
520 Packages must be placed in <em>non-free</em> or
521 <em>non-US/non-free</em> if they are not compliant with
522 the DFSG or are encumbered by patents or other legal
523 issues that make their distribution problematic.
527 In addition, the packages in <em>non-free</em> and
528 <em>non-US/non-free</em>
529 <list compact="compact">
531 must not be so buggy that we refuse to support them,
535 must meet all policy requirements presented in this
536 manual that it is possible for them to meet.
538 It is possible that there are policy
539 requirements which the package is unable to
540 meet, for example, if the source is
541 unavailable. These situations will need to be
542 handled on a case-by-case basis.
550 <heading>The non-US sections</heading>
553 Non-free programs with cryptographic program code need to
554 be stored on the <em>non-us</em> server because of export
555 restrictions of the U.S.
559 Programs which use patented algorithms that have a
560 restricted license also need to be stored on "non-us",
561 since that is located in a country where it is not allowed
562 to patent algorithms.
566 A package depends on another package which is distributed
567 via the non-us server has to be stored on the non-us
573 <sect id="pkgcopyright">
574 <heading>Copyright considerations</heading>
577 Every package must be accompanied by a verbatim copy of
578 its copyright and distribution license in the file
579 <file>/usr/share/doc/<var>package</var>/copyright</file>
580 (see <ref id="copyrightfile"> for further details).
584 We reserve the right to restrict files from being included
585 anywhere in our archives if
586 <list compact="compact">
588 their use or distribution would break a law,
591 there is an ethical conflict in their distribution or
595 we would have to sign a license for them, or
598 their distribution would conflict with other project
605 Programs whose authors encourage the user to make
606 donations are fine for the main distribution, provided
607 that the authors do not claim that not donating is
608 immoral, unethical, illegal or something similar; in such
609 a case they must go in <em>non-free</em>.
613 Packages whose copyright permission notices (or patent
614 problems) do not even allow redistribution of binaries
615 only, and where no special permission has been obtained,
616 must not be placed on the Debian FTP site and its mirrors
621 Note that under international copyright law (this applies
622 in the United States, too), <em>no</em> distribution or
623 modification of a work is allowed without an explicit
624 notice saying so. Therefore a program without a copyright
625 notice <em>is</em> copyrighted and you may not do anything
626 to it without risking being sued! Likewise if a program
627 has a copyright notice but no statement saying what is
628 permitted then nothing is permitted.
632 Many authors are unaware of the problems that restrictive
633 copyrights (or lack of copyright notices) can cause for
634 the users of their supposedly-free software. It is often
635 worthwhile contacting such authors diplomatically to ask
636 them to modify their license terms. However, this can be a
637 politically difficult thing to do and you should ask for
638 advice on the <tt>debian-legal</tt> mailing list first, as
643 When in doubt about a copyright, send mail to
644 <email>debian-legal@lists.debian.org</email>. Be prepared
645 to provide us with the copyright statement. Software
646 covered by the GPL, public domain software and BSD-like
647 copyrights are safe; be wary of the phrases "commercial
648 use prohibited" and "distribution restricted".
652 <sect id="subsections">
653 <heading>Subsections</heading>
656 The packages in the sections <em>main</em>,
657 <em>contrib</em> and <em>non-free</em> are grouped further
658 into <em>subsections</em> to simplify handling.
662 The section and subsection for each package should be
663 specified in the package's <tt>Section</tt> control
664 record (see <ref id="f-Section">).
665 However, the maintainer of the Debian archive
666 may override this selection to ensure the consistency of
667 the Debian distribution. The <tt>Section</tt> field
668 should be of the form:
669 <list compact="compact">
671 <em>subsection</em> if the package is in the
672 <em>main</em> section,
675 <em>section/subsection</em> if the package is in
676 the <em>contrib</em> or <em>non-free</em> section,
680 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
681 <tt>non-US/non-free</tt> if the package is in
682 <em>non-US/main</em>, <em>non-US/contrib</em> or
683 <em>non-US/non-free</em> respectively.
689 The Debian archive maintainers provide the authoritative
690 list of subsections. At present, they are:
691 <em>admin</em>, <em>base</em>, <em>comm</em>,
692 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
693 <em>editors</em>, <em>electronics</em>, <em>embedded</em>,
694 <em>games</em>, <em>gnome</em> <em>graphics</em>,
695 <em>hamradio</em>, <em>interpreters</em>, <em>kde</em>,
696 <em>libs</em>, <em>libdevel</em>, <em>mail</em>,
697 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
698 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
699 <em>otherosfs</em>, <em>perl</em>, <em>python</em>
700 <em>science</em>, <em>shells</em>,
701 <em>sound</em>, <em>tex</em>, <em>text</em>,
702 <em>utils</em>, <em>web</em>, <em>x11</em>.
706 <sect id="priorities">
707 <heading>Priorities</heading>
710 Each package should have a <em>priority</em> value, which is
711 included in the package's <em>control record</em>
712 (see <ref id="f-Priority">).
713 This information is used by the Debian package management tools to
714 separate high-priority packages from less-important packages.
718 The following <em>priority levels</em> are recognised by the
719 Debian package management tools.
721 <tag><tt>required</tt></tag>
723 Packages which are necessary for the proper
724 functioning of the system. You must not remove these
725 packages or your system may become totally broken and
726 you may not even be able to use <prgn>dpkg</prgn> to
727 put things back. Systems with only the
728 <tt>required</tt> packages are probably unusable, but
729 they do have enough functionality to allow the
730 sysadmin to boot and install more software.
732 <tag><tt>important</tt></tag>
734 Important programs, including those which one would
735 expect to find on any Unix-like system. If the
736 expectation is that an experienced Unix person who
737 found it missing would say "What on earth is going on,
738 where is <prgn>foo</prgn>?", it must be an
739 <tt>important</tt> package.<footnote>
740 This is an important criterion because we are
741 trying to produce, amongst other things, a free
744 Other packages without which the system will not run
745 well or be usable must also have priority
746 <tt>important</tt>. This does
747 <em>not</em> include Emacs, the X Window System, TeX
748 or any other large applications. The
749 <tt>important</tt> packages are just a bare minimum of
750 commonly-expected and necessary tools.
752 <tag><tt>standard</tt></tag>
754 These packages provide a reasonably small but not too
755 limited character-mode system. This is what will be
756 installed by default if the user doesn't select anything
757 else. It doesn't include many large applications.
759 <tag><tt>optional</tt></tag>
761 (In a sense everything that isn't required is
762 optional, but that's not what is meant here.) This is
763 all the software that you might reasonably want to
764 install if you didn't know what it was and don't have
765 specialized requirements. This is a much larger system
766 and includes the X Window System, a full TeX
767 distribution, and many applications. Note that
768 optional packages should not conflict with each other.
770 <tag><tt>extra</tt></tag>
772 This contains all packages that conflict with others
773 with required, important, standard or optional
774 priorities, or are only likely to be useful if you
775 already know what they are or have specialised
782 Packages must not depend on packages with lower priority
783 values (excluding build-time dependencies). In order to
784 ensure this, the priorities of one or more packages may need
793 <heading>Binary packages</heading>
796 The Debian GNU/Linux distribution is based on the Debian
797 package management system, called <prgn>dpkg</prgn>. Thus,
798 all packages in the Debian distribution must be provided
799 in the <tt>.deb</tt> file format.
803 <heading>The package name</heading>
806 Every package must have a name that's unique within the Debian
811 The package name is part of the file name of the
812 <tt>.deb</tt> file and is included in the control field
817 Format is described in <ref id="f-Package">.
822 <heading>The version of a package</heading>
825 Every package has a version number recorded in its
826 <tt>Version</tt> control file field, described in
827 <ref id="f-Version">.
831 The package management system imposes an ordering on version
832 numbers, so that it can tell whether packages are being up- or
833 downgraded and so that package system front end applications
834 can tell whether a package it finds available is newer than
835 the one installed on the system. The version number format
836 has the most significant parts (as far as comparison is
837 concerned) at the beginning.
841 If an upstream package has problematic version numbers they
842 should be converted to a sane form for use in the
843 <tt>Version</tt> field.
847 <heading>Version numbers based on dates</heading>
850 In general, Debian packages should use the same version
851 numbers as the upstream sources.
855 However, in some cases where the upstream version number is
856 based on a date (e.g., a development "snapshot" release) the
857 package management system cannot handle these version
858 numbers without epochs. For example, dpkg will consider
859 "96May01" to be greater than "96Dec24".
863 To prevent having to use epochs for every new upstream
864 version, the version number should be changed to the
865 following format in such cases: "19960501", "19961224". It
866 is up to the maintainer whether he/she wants to bother the
867 upstream maintainer to change the version numbers upstream,
872 Note that other version formats based on dates which are
873 parsed correctly by the package management system should
874 <em>not</em> be changed.
878 Native Debian packages (i.e., packages which have been
879 written especially for Debian) whose version numbers include
880 dates should always use the "YYYYMMDD" format.
887 <heading>The maintainer of a package</heading>
890 Every package must have a Debian maintainer (the
891 maintainer may be one person or a group of people
892 reachable from a common email address, such as a mailing
893 list). The maintainer is responsible for ensuring that
894 the package is placed in the appropriate distributions.
898 The maintainer must be specified in the
899 <tt>Maintainer</tt> control field with their correct name
900 and a working email address. If one person maintains
901 several packages, he/she should try to avoid having
902 different forms of their name and email address in
903 the <tt>Maintainer</tt> fields of those packages.
907 The format of the <tt>Maintainer</tt> control field is
908 described in <ref id="f-Maintainer">.
912 If the maintainer of a package quits from the Debian
913 project, "Debian QA Group"
914 <email>packages@qa.debian.org</email> takes over the
915 maintainership of the package until someone else
916 volunteers for that task. These packages are called
917 <em>orphaned packages</em>.<footnote>
918 The detailed procedure for doing this gracefully can
919 be found in the Debian Developer's Reference,
920 see <ref id="related">.
925 <sect id="descriptions">
926 <heading>The description of a package</heading>
929 Every Debian package must have an extended description
930 stored in the appropriate field of the control record.
931 The technical information about the format of the
932 <tt>Description</tt> field is in <ref id="f-Description">.
936 The description should describe the package (the program) to a
937 user (system administrator) who has never met it before so that
938 they have enough information to decide whether they want to
939 install it. This description should not just be copied verbatim
940 from the program's documentation.
944 Put important information first, both in the synopsis and
945 extended description. Sometimes only the first part of the
946 synopsis or of the description will be displayed. You can
947 assume that there will usually be a way to see the whole
948 extended description.
952 The description should also give information about the
953 significant dependencies and conflicts between this package
954 and others, so that the user knows why these dependencies and
955 conflicts have been declared.
959 Instructions for configuring or using the package should
960 not be included (that is what installation scripts,
961 manual pages, info files, etc., are for). Copyright
962 statements and other administrivia should not be included
963 either (that is what the copyright file is for).
966 <sect1 id="synopsis"><heading>The single line synopsis</heading>
969 The single line synopsis should be kept brief - certainly
974 Do not include the package name in the synopsis line. The
975 display software knows how to display this already, and you
976 do not need to state it. Remember that in many situations
977 the user may only see the synopsis line - make it as
978 informative as you can.
983 <sect1 id="extendeddesc"><heading>The extended description</heading>
986 Do not try to continue the single line synopsis into the
987 extended description. This will not work correctly when
988 the full description is displayed, and makes no sense
989 where only the summary (the single line synopsis) is
994 The extended description should describe what the package
995 does and how it relates to the rest of the system (in terms
996 of, for example, which subsystem it is which part of).
1000 The description field needs to make sense to anyone, even
1001 people who have no idea about any of the things the
1002 package deals with.<footnote>
1003 The blurb that comes with a program in its
1004 announcements and/or <prgn>README</prgn> files is
1005 rarely suitable for use in a description. It is
1006 usually aimed at people who are already in the
1007 community where the package is used.
1016 <heading>Dependencies</heading>
1019 Every package must specify the dependency information
1020 about other packages that are required for the first to
1025 For example, a dependency entry must be provided for any
1026 shared libraries required by a dynamically-linked executable
1027 binary in a package.
1031 Packages are not required to declare any dependencies they
1032 have on other packages which are marked <tt>Essential</tt>
1033 (see below), and should not do so unless they depend on a
1034 particular version of that package.
1038 Sometimes, a package requires another package to be installed
1039 <em>and</em> configured before it can be installed. In this
1040 case, you must specify a <tt>Pre-Depends</tt> entry for
1045 You should not specify a <tt>Pre-Depends</tt> entry for a
1046 package before this has been discussed on the
1047 <tt>debian-devel</tt> mailing list and a consensus about
1048 doing that has been reached.
1052 The format of the package interrelationship control fields is
1053 described in <ref id="relationships">.
1057 <sect id="virtual_pkg">
1058 <heading>Virtual packages</heading>
1061 Sometimes, there are several packages which offer
1062 more-or-less the same functionality. In this case, it's
1063 useful to define a <em>virtual package</em> whose name
1064 describes that common functionality. (The virtual
1065 packages only exist logically, not physically; that's why
1066 they are called <em>virtual</em>.) The packages with this
1067 particular function will then <em>provide</em> the virtual
1068 package. Thus, any other package requiring that function
1069 can simply depend on the virtual package without having to
1070 specify all possible packages individually.
1074 All packages should use virtual package names where
1075 appropriate, and arrange to create new ones if necessary.
1076 They should not use virtual package names (except privately,
1077 amongst a cooperating group of packages) unless they have
1078 been agreed upon and appear in the list of virtual package
1079 names. (See also <ref id="virtual">)
1083 The latest version of the authoritative list of virtual
1084 package names can be found in the <tt>debian-policy</tt> package.
1085 It is also available from the Debian web mirrors at
1086 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1087 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
1088 and from the Debian archive mirrors at
1089 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
1090 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
1094 The procedure for updating the list is described in the preface
1101 <heading>Base system</heading>
1104 The <tt>base system</tt> is a minimum subset of the Debian
1105 GNU/Linux system that is installed before everything else
1106 on a new system. Thus, only very few packages are allowed
1107 to go into the <tt>base</tt> section to keep the required
1108 disk usage very small.
1112 Most of these packages will have the priority value
1113 <tt>required</tt> or at least <tt>important</tt>, and many
1114 of them will be tagged <tt>essential</tt> (see below).
1119 <heading>Essential packages</heading>
1122 Some packages are tagged <tt>essential</tt> for a system
1123 using the <tt>Essential</tt> control file field.
1124 The format of the <tt>Essential</tt> control field is
1125 described in <ref id="f-Essential">.
1129 Since these packages cannot be easily removed (one has to
1130 specify an extra <em>force option</em> to
1131 <prgn>dpkg</prgn> to do so), this flag must not be used
1132 unless absolutely necessary. A shared library package
1133 must not be tagged <tt>essential</tt>; dependencies will
1134 prevent its premature removal, and we need to be able to
1135 remove it when it has been superseded.
1139 Since dpkg will not prevent upgrading of other packages
1140 while an <tt>essential</tt> package is in an unconfigured
1141 state, all <tt>essential</tt> packages must supply all of
1142 their core functionality even when unconfigured. If the
1143 package cannot satisfy this requirement it must not be
1144 tagged as essential, and any packages depending on this
1145 package must instead have explicit dependency fields as
1150 You must not tag any packages <tt>essential</tt> before
1151 this has been discussed on the <tt>debian-devel</tt>
1152 mailing list and a consensus about doing that has been
1158 <heading>Tasks</heading>
1161 The Debian install process allows the user to choose from
1162 a number of common tasks which a Debian system can be used to
1163 perform. Selecting a task with <prgn>tasksel</prgn> causes
1164 a set of packages that are useful in performing that task to be
1169 This set of packages is all available packages which have the
1170 name of the selected task in the <tt>Task</tt> field of their
1171 control file. The format of this field is a list of tasks,
1172 separated by commas.
1176 You should not tag any packages as belonging to a task
1177 before this has been discussed on the
1178 <em>debian-devel</em> mailing list and a consensus about
1179 doing that has been reached.
1183 For third parties (and historical reasons), tasksel also
1184 supports constructing tasks based on <em>task
1185 packages</em>. These are packages whose names begin with
1186 <em>task-</em>. Task packages should not be included in the
1191 <sect id="maintscripts">
1192 <heading>Maintainer Scripts</heading>
1195 The package installation scripts should avoid producing
1196 output which it is unnecessary for the user to see and
1197 should rely on <prgn>dpkg</prgn> to stave off boredom on
1198 the part of a user installing many packages. This means,
1199 amongst other things, using the <tt>--quiet</tt> option on
1200 <prgn>install-info</prgn>.
1204 Errors which occur during the execution of an installation
1205 script must be checked and the installation must not
1206 continue after an error.
1210 Note that in general <ref id="scripts"> applies to package
1211 maintainer scripts, too.
1215 You should not use <prgn>dpkg-divert</prgn> on a file
1216 belonging to another package without consulting the
1217 maintainer of that package first.
1221 All packages which supply an instance of a common command
1222 name (or, in general, filename) should generally use
1223 <prgn>update-alternatives</prgn>, so that they may be
1224 installed together. If <prgn>update-alternatives</prgn>
1225 is not used, then each package must use
1226 <tt>Conflicts</tt> to ensure that other packages are
1227 de-installed. (In this case, it may be appropriate to
1228 specify a conflict against earlier versions of something
1229 that previously did not use
1230 <prgn>update-alternatives</prgn>; this is an exception to
1231 the usual rule that versioned conflicts should be
1235 <sect1 id="maintscriptprompt">
1236 <heading>Prompting in maintainer scripts</heading>
1238 Package maintainer scripts may prompt the user if
1239 necessary. Prompting may be accomplished by hand<footnote>
1240 From the Jargon file: by hand 2. By extension,
1241 writing code which does something in an explicit or
1242 low-level way for which a presupplied library
1243 (<em>debconf, in this instance</em>) routine ought
1244 to have been available.
1246 (but this is deprecated), or by communicating through a program
1247 which conforms to the Debian Configuration management
1248 specification, version 2 or higher, such as
1249 <prgn>debconf</prgn><footnote>
1251 6% of Debian packages [see <url
1252 id="http://ftp-master.debian.org/~joeyh/debconf-stats/"
1253 name="Debconf stats">] currently use
1254 <package>debconf</package> to prompt the user at
1255 install time, and this number is growing daily. The
1256 benefits of using debconf are briefly explained at
1258 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1259 name="Debconf introduction">; they include
1260 preconfiguration, (mostly) noninteractive
1261 installation, elimination of redundant prompting,
1262 consistency of user interface, etc.
1266 With this increasing number of packages using
1267 <package>debconf</package>, plus the existence of a
1268 nascent second implementation of the Debian
1269 configuration management system
1270 (<package>cdebconf</package>), and the stabilization
1271 of the protocol these things use, the time has
1272 finally come to reflect the use of these things in
1279 The Debian Configuration management specification is included
1280 in the <file>debconf_specification</file> files in the
1281 <package>debian-policy</package> package.
1282 It is also available from the Debian web mirrors at
1283 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1284 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>
1285 and from the Debian archive mirrors at
1286 <tt><url name="/doc/package-developer/debconf_specification.txt.gz"
1287 id="http://ftp.debian.org/debian/doc/package-developer/debconf_specification.txt.gz"></tt>.
1291 Packages which use the Debian Configuration management
1292 specification may contain an additional
1293 <prgn>config</prgn> script and a <tt>templates</tt>
1294 file in their control archive. The <prgn>config</prgn>
1295 script might be run before the <prgn>preinst</prgn>
1296 script, and before the package is unpacked or any of its
1297 dependencies or pre-dependancies are satisfied.
1298 Therefore it must work using only the tools present in
1299 <em>essential</em> packages.<footnote>
1300 <package>Debconf</package> or another tool that
1301 implements the Debian Configuration management
1302 specification will also be installed, and any
1303 versioned dependencies on it will be satisfied
1304 before preconfiguration begins.
1309 Packages should try to minimize the amount of prompting
1310 they need to do, and they should ensure that the user
1311 will only ever be asked each question once. This means
1312 that packages should try to use appropriate shared
1313 configuration files (such as <file>/etc/papersize</file> and
1314 <file>/etc/news/server</file>), and shared
1315 <package>debconf</package> variables rather than each
1316 prompting for their own list of required pieces of
1321 It also means that an upgrade should not ask the same
1322 questions again, unless the user has used
1323 <tt>dpkg --purge</tt> to remove the package's configuration.
1324 The answers to configuration questions should be stored in an
1325 appropriate place in <file>/etc</file> so that the user can
1326 modify them, and how this has been done should be
1331 If a package has a vitally important piece of
1332 information to pass to the user (such as "don't run me
1333 as I am, you must edit the following configuration files
1334 first or you risk your system emitting badly-formatted
1335 messages"), it should display this in the
1336 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1337 prompt the user to hit return to acknowledge the
1338 message. Copyright messages do not count as vitally
1339 important (they belong in
1340 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1341 neither do instructions on how to use a program (these
1342 should be in on-line documentation, where all the users
1347 Any necessary prompting should almost always be confined
1348 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1349 script. If it is done in the <prgn>postinst</prgn>, it
1350 should be protected with a conditional so that
1351 unnecessary prompting doesn't happen if a package's
1352 installation fails and the <prgn>postinst</prgn> is
1353 called with <tt>abort-upgrade</tt>,
1354 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1364 <heading>Source packages</heading>
1366 <sect id="standardsversion">
1367 <heading>Standards conformance</heading>
1370 Source packages should specify the most recent version number
1371 of this policy document with which your package complied
1372 when it was last updated.
1376 This information may be used to file bug reports
1377 automatically if your package becomes too much out of date.
1381 The version is specified in the <tt>Standards-Version</tt>
1383 The format of the <tt>Standards-Version</tt> field is
1384 described in <ref id="f-Standards-Version">.
1388 You should regularly, and especially if your package has
1389 become out of date, check for the newest Policy Manual
1390 available and update your package, if necessary. When your
1391 package complies with the new standards you should update the
1392 <tt>Standards-Version</tt> source package field and
1393 release it.<footnote>
1394 See the file <file>upgrading-checklist</file> for
1395 information about policy which has changed between
1396 different versions of this document.
1402 <sect id="pkg-relations">
1403 <heading>Package relationships</heading>
1406 Source packages should specify which binary packages they
1407 require to be installed or not to be installed in order to
1408 build correctly. For example, if building a package
1409 requires a certain compiler, then the compiler should be
1410 specified as a build-time dependency.
1414 It is not necessary to explicitly specify build-time
1415 relationships on a minimal set of packages that are always
1416 needed to compile, link and put in a Debian package a
1417 standard "Hello World!" program written in C or C++. The
1418 required packages are called <em>build-essential</em>, and
1419 an informational list can be found in
1420 <file>/usr/share/doc/build-essential/list</file> (which is
1421 contained in the <tt>build-essential</tt>
1424 <list compact="compact">
1426 This allows maintaining the list separately
1427 from the policy documents (the list does not
1428 need the kind of control that the policy
1432 Having a separate package allows one to install
1433 the build-essential packages on a machine, as
1434 well as allowing other packages such as tasks to
1435 require installation of the build-essential
1436 packages using the depends relation.
1439 The separate package allows bug reports against
1440 the list to be categorized separately from
1441 the policy management process in the BTS.
1448 When specifying the set of build-time dependencies, one
1449 should list only those packages explicitly required by the
1450 build. It is not necessary to list packages which are
1451 required merely because some other package in the list of
1452 build-time dependencies depends on them.<footnote>
1453 The reason for this is that dependencies change, and
1454 you should list all those packages, and <em>only</em>
1455 those packages that <em>you</em> need directly. What
1456 others need is their business. For example, if you
1457 only link against <file>libimlib</file>, you will need to
1458 build-depend on <package>libimlib2-dev</package> but
1459 not against any <tt>libjpeg*</tt> packages, even
1460 though <tt>libimlib2-dev</tt> currently depends on
1461 them: installation of <package>libimlib2-dev</package>
1462 will automatically ensure that all of its run-time
1463 dependencies are satisfied.
1468 If build-time dependencies are specified, it must be
1469 possible to build the package and produce working binaries
1470 on a system with only essential and build-essential
1471 packages installed and also those required to satisfy the
1472 build-time relationships (including any implied
1473 relationships). In particular, this means that version
1474 clauses should be used rigorously in build-time
1475 relationships so that one cannot produce bad or
1476 inconsistently configured packages when the relationships
1477 are properly satisfied.
1481 <ref id="relationships"> explains the technical details.
1486 <heading>Changes to the upstream sources</heading>
1489 If changes to the source code are made that are not
1490 specific to the needs of the Debian system, they should be
1491 sent to the upstream authors in whatever form they prefer
1492 so as to be included in the upstream version of the
1497 If you need to configure the package differently for
1498 Debian or for Linux, and the upstream source doesn't
1499 provide a way to do so, you should add such configuration
1500 facilities (for example, a new <prgn>autoconf</prgn> test
1501 or <tt>#define</tt>) and send the patch to the upstream
1502 authors, with the default set to the way they originally
1503 had it. You can then easily override the default in your
1504 <file>debian/rules</file> or wherever is appropriate.
1508 You should make sure that the <prgn>configure</prgn> utility
1509 detects the correct architecture specification string
1510 (refer to <ref id="arch-spec"> for details).
1514 If you need to edit a <prgn>Makefile</prgn> where
1515 GNU-style <prgn>configure</prgn> scripts are used, you
1516 should edit the <file>.in</file> files rather than editing the
1517 <prgn>Makefile</prgn> directly. This allows the user to
1518 reconfigure the package if necessary. You should
1519 <em>not</em> configure the package and edit the generated
1520 <prgn>Makefile</prgn>! This makes it impossible for
1521 someone else to later reconfigure the package.
1526 <sect id="dpkgchangelog">
1527 <heading>Debian changelog: <file>debian/changelog</file></heading>
1530 Changes in the Debian version of the package should be
1531 briefly explained in the Debian changelog file
1532 <file>debian/changelog</file>. This includes modifications
1533 made in the Debian package compared to the upstream one
1534 as well as other changes and updates to the package.
1536 Although there is nothing stopping an author who is also
1537 the Debian maintainer from using this changelog for all
1538 their changes, it will have to be renamed if the Debian
1539 and upstream maintainers become different people. In such
1540 a case, however, it might be better to maintain the package
1541 as a non-native package.
1546 Mistakes in changelogs are usually best rectified by making
1547 a new changelog entry rather than "rewriting history" by
1548 editing old changelog entries.
1552 The format of the <file>debian/changelog</file> allows the
1553 package building tools to discover which version of the package
1554 is being built and find out other release-specific information.
1558 That format is a series of entries like this:
1560 <example compact="compact">
1561 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1563 [optional blank line(s), stripped]
1565 * <var>change details</var>
1566 <var>more change details</var>
1568 [blank line(s), included in output of dpkg-parsechangelog]
1570 * <var>even more change details</var>
1572 [optional blank line(s), stripped]
1574 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1579 <var>package</var> and <var>version</var> are the source
1580 package name and version number.
1584 <var>distribution(s)</var> lists the distributions where
1585 this version should be installed when it is uploaded - it
1586 is copied to the <tt>Distribution</tt> field in the
1587 <file>.changes</file> file. See <ref id="f-Distribution">.
1591 <var>urgency</var> is the value for the <tt>Urgency</tt>
1592 field in the <file>.changes</file> file for the upload
1593 (see <ref id="f-Urgency">). It is not possible to specify
1594 an urgency containing commas; commas are used to separate
1595 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1596 <prgn>dpkg</prgn> changelog format (though there is
1597 currently only one useful <var>keyword</var>,
1598 <tt>urgency</tt>).<footnote>
1599 Recognised urgency values are <tt>low</tt>,
1600 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
1601 They have an effect on how quickly a package will be
1602 considered for inclusion into the <tt>testing</tt>
1603 distribution, and give an indication of the importance
1604 of any fixes included in this upload.
1609 The change details may in fact be any series of lines
1610 starting with at least two spaces, but conventionally each
1611 change starts with an asterisk and a separating space and
1612 continuation lines are indented so as to bring them in
1613 line with the start of the text above. Blank lines may be
1614 used here to separate groups of changes, if desired.
1618 If this upload resolves bugs recorded in the Bug Tracking
1619 System (BTS), they may be automatically closed on the
1620 inclusion of this package into the Debian archive by
1621 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1622 in the change details.<footnote>
1623 To be precise, the string should match the following
1624 Perl regular expression:
1626 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1628 Then all of the bug numbers listed will be closed by the
1629 archive maintenance script (<prgn>katie</prgn>), or in
1630 the case of an NMU, marked as fixed.
1632 This information is conveyed via the <tt>Closes</tt> field
1633 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1637 The maintainer name and email address used in the changelog
1638 should be the details of the person uploading <em>this</em>
1639 version. They are <em>not</em> necessarily those of the
1640 usual package maintainer. The information here will be
1641 copied to the <tt>Changed-By</tt> field in the
1642 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1643 and then later used to send an acknowledgement when the
1644 upload has been installed.
1648 The <var>date</var> should be in RFC822 format<footnote>
1649 This is generated by the <prgn>822-date</prgn>
1651 </footnote>; it should include the time zone specified
1652 numerically, with the time zone name or abbreviation
1653 optionally present as a comment in parentheses.
1657 The first "title" line with the package name should start
1658 at the left hand margin; the "trailer" line with the
1659 maintainer and date details should be preceded by exactly
1660 one space. The maintainer details and the date must be
1661 separated by exactly two spaces.
1665 For more information on placement of the changelog files
1666 within binary packages, please see <ref id="changelogs">.
1669 <sect1><heading>Alternative changelog formats</heading>
1672 In non-experimental packages you must use a format for
1673 <file>debian/changelog</file> which is supported by the most
1674 recent released version of <prgn>dpkg</prgn>.
1676 If there is general interest in the new format, you should
1677 contact the <package>dpkg</package> maintainer to have the
1678 parser script for it included in the <prgn>dpkg</prgn>
1679 package. (You will need to agree that the parser and its
1680 manpage may be distributed under the GNU GPL, just as the rest
1681 of <prgn>dpkg</prgn> is.)
1686 It is possible to use a format different from the standard
1687 one by providing a changelog parser for the format you wish
1688 to use. The parser must have an API compatible with that
1689 expected by <prgn>dpkg-genchanges</prgn> and
1690 <prgn>dpkg-gencontrol</prgn>, and it must not interact with
1697 <heading>Error trapping in makefiles</heading>
1700 When <prgn>make</prgn> invokes a command in a makefile
1701 (including your package's upstream makefiles and
1702 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1703 means that <prgn>sh</prgn>'s usual bad error handling
1704 properties apply: if you include a miniature script as one
1705 of the commands in your makefile you'll find that if you
1706 don't do anything about it then errors are not detected
1707 and <prgn>make</prgn> will blithely continue after
1712 Every time you put more than one shell command (this
1713 includes using a loop) in a makefile command you
1714 must make sure that errors are trapped. For
1715 simple compound commands, such as changing directory and
1716 then running a program, using <tt>&&</tt> rather
1717 than semicolon as a command separator is sufficient. For
1718 more complex commands including most loops and
1719 conditionals you should include a separate <tt>set -e</tt>
1720 command at the start of every makefile command that's
1721 actually one of these miniature shell scripts.
1725 <sect id="timestamps">
1726 <heading>Time Stamps</heading>
1728 Maintainers should preserve the modification times of the
1729 upstream source files in a package, as far as is reasonably
1731 The rationale is that there is some information conveyed
1732 by knowing the age of the file, for example, you could
1733 recognize that some documentation is very old by looking
1734 at the modification time, so it would be nice if the
1735 modification time of the upstream source would be
1741 <sect id="restrictions">
1742 <heading>Restrictions on objects in source packages</heading>
1745 The source package may not contain any hard links<footnote>
1747 This is not currently detected when building source
1748 packages, but only when extracting
1752 Hard links may be permitted at some point in the
1753 future, but would require a fair amount of
1756 </footnote>, device special files, sockets or setuid or
1757 setgid files.<footnote>
1758 Setgid directories are allowed.
1764 <heading>Obsolete constructs and libraries</heading>
1767 The include file <tt><varargs.h></tt> is
1768 provided to support end-users compiling very old software;
1769 the library <tt>libtermcap</tt> is provided to support the
1770 execution of software which has been linked against it
1771 (either old programs or those such as Netscape which are
1772 only available in binary form).
1776 Debian packages should be patched to use
1777 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1782 <sect id="debianrules">
1783 <heading>Main building script: <file>debian/rules</file></heading>
1786 This file must be an executable makefile, and contains the
1787 package-specific recipes for compiling the package and
1788 building binary package(s) from the source.
1792 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1793 so that it can be invoked by saying its name rather than
1794 invoking <prgn>make</prgn> explicitly.
1798 Since an interactive <file>debian/rules</file> script makes it
1799 impossible to auto-compile that package and also makes it
1800 hard for other people to reproduce the same binary
1801 package, all <em>required targets</em> MUST be
1802 non-interactive. At a minimum, required targets are the
1803 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1804 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1805 <em>binary-indep</em>, and <em>build</em>. It also follows
1806 that any target that these targets depend on must also be
1811 The targets are as follows (required unless stated otherwise):
1813 <tag><tt>build</tt></tag>
1816 The <tt>build</tt> target should perform all
1817 non-interactive configuration and compilation of the
1818 package. If a package has an interactive pre-build
1819 configuration routine, the Debianized source package
1820 must either be built after this has taken place (so
1821 that the binary package can be built without rerunning
1822 the configuration) or the configuration routine
1823 modified to become non-interactive. (The latter is
1824 preferable if there are architecture-specific features
1825 detected by the configuration routine.)
1829 For some packages, notably ones where the same
1830 source tree is compiled in different ways to produce
1831 two binary packages, the <tt>build</tt> target
1832 does not make much sense. For these packages it is
1833 good enough to provide two (or more) targets
1834 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1835 for each of the ways of building the package, and a
1836 <tt>build</tt> target that does nothing. The
1837 <tt>binary</tt> target will have to build the
1838 package in each of the possible ways and make the
1839 binary package out of each.
1843 The <tt>build</tt> target must not do anything
1844 that might require root privilege.
1848 The <tt>build</tt> target may need to run the
1849 <tt>clean</tt> target first - see below.
1853 When a package has a configuration and build routine
1854 which takes a long time, or when the makefiles are
1855 poorly designed, or when <tt>build</tt> needs to
1856 run <tt>clean</tt> first, it is a good idea to
1857 <tt>touch build</tt> when the build process is
1858 complete. This will ensure that if <tt>debian/rules
1859 build</tt> is run again it will not rebuild the whole
1861 Another common way to do this is for <tt>build</tt>
1862 to depend on <prgn>build-stamp</prgn> and to do
1863 nothing else, and for the <prgn>build-stamp</prgn>
1864 target to do the building and to <tt>touch
1865 build-stamp</tt> on completion. This is
1866 especially useful if the build routine creates a
1867 file or directory called <tt>build</tt>; in such a
1868 case, <tt>build</tt> will need to be listed as
1869 a phony target (i.e., as a dependency of the
1870 <tt>.PHONY</tt> target). See the documentation of
1871 <prgn>make</prgn> for more information on phony
1877 <tag><tt>build-arch</tt> (optional),
1878 <tt>build-indep</tt> (optional)
1882 A package may also provide both of the targets
1883 <tt>build-arch</tt> and <tt>build-indep</tt>.
1884 The <tt>build-arch</tt> target, if provided, should
1885 perform all non-interactive configuration and
1886 compilation required for producing all
1887 architecture-dependant binary packages (those packages
1888 for which the body of the <tt>Architecture</tt> field
1889 in <tt>debian/control</tt> is not <tt>all</tt>).
1890 Similarly, the <tt>build-indep</tt> target, if
1891 provided, should perform all non-interactive
1892 configuration and compilation required for producing
1893 all architecture-independent binary packages (those
1894 packages for which the body of the
1895 <tt>Architecture</tt> field in <tt>debian/control</tt>
1896 is <tt>all</tt>). The <tt>build</tt> target should
1897 depend on those of the targets <tt>build-arch</tt> and
1898 <tt>build-indep</tt> that are provided in the rules
1903 If one or both of the targets <tt>build-arch</tt> and
1904 <tt>build-indep</tt> are not provided, then invoking
1905 <file>debian/rules</file> with one of the not-provided
1906 targets as arguments should produce a exit status code
1907 of 2. Usually this is provided automatically by make
1908 if the target is missing.
1912 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1913 must not do anything that might require root privilege.
1917 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1918 <tt>binary-indep</tt>
1922 The <tt>binary</tt> target must be all that is
1923 necessary for the user to build the binary package(s)
1924 produced from this source package. All of these
1925 targets are required to be non-interactive. It is
1926 split into two parts: <prgn>binary-arch</prgn> builds
1927 the binary packages which are specific to a particular
1928 architecture, and <tt>binary-indep</tt> builds
1929 those which are not.
1932 <tt>binary</tt> may be (and commonly is) a target with
1933 no commands which simply depends on
1934 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1937 Both <tt>binary-*</tt> targets should depend on the
1938 <tt>build</tt> target, or on the appropriate
1939 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1940 provided, so that the package is built if it has not
1941 been already. It should then create the relevant
1942 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1943 make their control files and <prgn>dpkg-deb</prgn> to
1944 build them and place them in the parent of the top
1949 Both the <tt>binary-arch</tt> and
1950 <tt>binary-indep</tt> targets <em>must</em> exist.
1951 If one of them has nothing to do (which will always be
1952 the case if the source generates only a single binary
1953 package, whether architecture-dependent or not), it
1954 must still exist and must always succeed.
1958 The <tt>binary</tt> targets must be invoked as
1960 The <prgn>fakeroot</prgn> package often allows one
1961 to build a package correctly even without being
1967 <tag><tt>clean</tt></tag>
1970 This must undo any effects that the <tt>build</tt>
1971 and <tt>binary</tt> targets may have had, except
1972 that it should leave alone any output files created in
1973 the parent directory by a run of a <tt>binary</tt>
1974 target. This target must be non-interactive.
1978 If a <tt>build</tt> file is touched at the end of
1979 the <tt>build</tt> target, as suggested above, it
1980 should be removed as the first action that
1981 <tt>clean</tt> performs, so that running
1982 <tt>build</tt> again after an interrupted
1983 <tt>clean</tt> doesn't think that everything is
1988 The <tt>clean</tt> target may need to be
1989 invoked as root if <tt>binary</tt> has been
1990 invoked since the last <tt>clean</tt>, or if
1991 <tt>build</tt> has been invoked as root (since
1992 <tt>build</tt> may create directories, for
1997 <tag><tt>get-orig-source</tt> (optional)</tag>
2000 This target fetches the most recent version of the
2001 original source package from a canonical archive site
2002 (via FTP or WWW, for example), does any necessary
2003 rearrangement to turn it into the original source
2004 tar file format described below, and leaves it in the
2009 This target may be invoked in any directory, and
2010 should take care to clean up any temporary files it
2015 This target is optional, but providing it if
2016 possible is a good idea.
2022 The <tt>build</tt>, <tt>binary</tt> and
2023 <tt>clean</tt> targets must be invoked with the current
2024 directory being the package's top-level directory.
2029 Additional targets may exist in <file>debian/rules</file>,
2030 either as published or undocumented interfaces or for the
2031 package's internal use.
2035 The architectures we build on and build for are determined
2036 by <prgn>make</prgn> variables using the utility
2037 <qref id="pkg-dpkgarch"><prgn>dpkg-architecture</prgn></qref>.
2038 You can determine the
2039 Debian architecture and the GNU style architecture
2040 specification string for the build machine (the machine type
2041 we are building on) as well as for the host machine (the
2042 machine type we are building for). Here is a list of
2043 supported <prgn>make</prgn> variables:
2044 <list compact="compact">
2046 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2049 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2050 specification string)
2053 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2054 <tt>DEB_*_GNU_TYPE</tt>)
2057 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2058 <tt>DEB_*_GNU_TYPE</tt>)
2060 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2061 the build machine or <tt>HOST</tt> for specification of the
2066 Backward compatibility can be provided in the rules file
2067 by setting the needed variables to suitable default
2068 values; please refer to the documentation of
2069 <prgn>dpkg-architecture</prgn> for details.
2073 It is important to understand that the <tt>DEB_*_ARCH</tt>
2074 string only determines which Debian architecture we are
2075 building on or for. It should not be used to get the CPU
2076 or system information; the GNU style variables should be
2081 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2082 <sect id="substvars">
2083 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2086 When <prgn>dpkg-gencontrol</prgn>,
2087 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2088 generate control files they perform variable substitutions
2089 on their output just before writing it. Variable
2090 substitutions have the form <tt>${<var>variable</var>}</tt>.
2091 The optional file <file>debian/substvars</file> contains
2092 variable substitutions to be used; variables can also be set
2093 directly from <file>debian/rules</file> using the <tt>-V</tt>
2094 option to the source packaging commands, and certain
2095 predefined variables are also available.
2099 The <file>debian/substvars</file> file is usually generated and
2100 modified dynamically by <file>debian/rules</file> targets, in
2101 which case it must be removed by the <tt>clean</tt> target.
2105 See <manref name="dpkg-source" section="1"> for full
2106 details about source variable substitutions, including the
2107 format of <file>debian/substvars</file>.</p>
2110 <sect id="debianfiles">
2111 <heading>Generated files list: <file>debian/files</file></heading>
2114 This file is not a permanent part of the source tree; it
2115 is used while building packages to record which files are
2116 being generated. <prgn>dpkg-genchanges</prgn> uses it
2117 when it generates a <file>.changes</file> file.
2121 It should not exist in a shipped source package, and so it
2122 (and any backup files or temporary files such as
2123 <file>files.new</file><footnote>
2124 <file>files.new</file> is used as a temporary file by
2125 <prgn>dpkg-gencontrol</prgn> and
2126 <prgn>dpkg-distaddfile</prgn> - they write a new
2127 version of <tt>files</tt> here before renaming it,
2128 to avoid leaving a corrupted copy if an error
2130 </footnote>) should be removed by the
2131 <tt>clean</tt> target. It may also be wise to
2132 ensure a fresh start by emptying or removing it at the
2133 start of the <tt>binary</tt> target.
2137 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2138 package, it adds an entry to <file>debian/files</file> for the
2139 <file>.deb</file> file that will be created when <tt>dpkg-deb
2140 --build</tt> is run for that binary package. So for most
2141 packages all that needs to be done with this file is to
2142 delete it in the <tt>clean</tt> target.
2146 If a package upload includes files besides the source
2147 package and any binary packages whose control files were
2148 made with <prgn>dpkg-gencontrol</prgn> then they should be
2149 placed in the parent of the package's top-level directory
2150 and <prgn>dpkg-distaddfile</prgn> should be called to add
2151 the file to the list in <file>debian/files</file>.</p>
2157 <chapt id="controlfields">
2158 <heading>Control files and their fields</heading>
2161 The package management system manipulates data represented in
2162 a common format, known as <em>control data</em>, stored in
2163 <em>control files</em>.
2164 Control files are used for source packages, binary packages and
2165 the <file>.changes</file> files which control the installation
2166 of uploaded files<footnote>
2167 <prgn>dpkg</prgn>'s internal databases are in a similar
2172 <sect id="controlsyntax">
2173 <heading>Syntax of control files</heading>
2176 A control file consists of one or more paragraphs of
2178 The paragraphs are also sometimes referred to as stanzas.
2180 The paragraphs are separated by blank lines. Some control
2181 files allow only one paragraph; others allow several, in
2182 which case each paragraph usually refers to a different
2183 package. (For example, in source packages, the first
2184 paragraph refers to the source package, and later paragraphs
2185 refer to binary packages generated from the source.)
2189 Each paragraph consists of a series of data fields; each
2190 field consists of the field name, followed by a colon and
2191 then the data/value associated with that field. It ends at
2192 the end of the line. Horizontal whitespace (spaces and
2193 tabs) may occur immediately before or after the value and is
2194 ignored there; it is conventional to put a single space
2195 after the colon. For example, a field might be:
2196 <example compact="compact">
2199 the field name is <tt>Package</tt> and the field value
2204 Some fields' values may span several lines; in this case
2205 each continuation line must start with a space or a tab.
2206 Any trailing spaces or tabs at the end of individual
2207 lines of a field value are ignored.
2211 Except where otherwise stated, only a single line of data is
2212 allowed and whitespace is not significant in a field body.
2213 Whitespace must not appear inside names (of packages,
2214 architectures, files or anything else) or version numbers,
2215 or between the characters of multi-character version
2220 Field names are not case-sensitive, but it is usual to
2221 capitalize the field names using mixed case as shown below.
2225 Blank lines, or lines consisting only of spaces and tabs,
2226 are not allowed within field values or between fields - that
2227 would mean a new paragraph.
2232 <sect id="sourcecontrolfiles">
2233 <heading>Source package control files -- <file>debian/control</file></heading>
2236 The <file>debian/control</file> file contains the most vital
2237 (and version-independent) information about the source package
2238 and about the binary packages it creates.
2242 The first paragraph of the control file contains information about
2243 the source package in general. The subsequent sets each describe a
2244 binary package that the source tree builds.
2248 The fields in the general paragraph (the first one, for the source
2251 <list compact="compact">
2252 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2253 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2254 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2255 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2256 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2257 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2262 The fields in the binary package paragraphs are:
2264 <list compact="compact">
2265 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2266 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2267 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2268 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2269 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2270 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2271 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2276 The syntax and semantics of the fields are described below.
2282 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2283 generate control files for binary packages (see below), by
2284 <prgn>dpkg-genchanges</prgn> to generate the
2285 <tt>.changes</tt> file to accompany the upload, and by
2286 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
2287 source control file as part of a source archive.
2291 The fields here may contain variable references - their
2292 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2293 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2294 when they generate output control files.
2295 See <ref id="substvars"> for details.
2300 <sect id="binarycontrolfiles">
2301 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2304 The <file>DEBIAN/control</file> file contains the most vital
2305 (and version-dependent) information about a binary package.
2309 The fields in this file are:
2311 <list compact="compact">
2312 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2313 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2314 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2315 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2316 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2317 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2318 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2319 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2320 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2321 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2322 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2327 <sect id="debiansourcecontrolfiles">
2328 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2331 This file contains a series of fields, identified and
2332 separated just like the fields in the control file of
2333 a binary package. The fields are listed below; their
2334 syntax is described above, in <ref id="pkg-controlfields">.
2336 <list compact="compact">
2337 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2338 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2339 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2340 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2341 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2342 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2343 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2344 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2349 The source package control file is generated by
2350 <prgn>dpkg-source</prgn> when it builds the source
2351 archive, from other files in the source package,
2352 described above. When unpacking, it is checked against
2353 the files and directories in the other parts of the
2354 source package (see).
2359 <sect id="debianchangesfiles">
2360 <heading>Debian changes files -- <file>.changes</file></heading>
2363 The .changes files are used by the Debian archive maintenance
2364 software to process updates to packages. They contain one
2365 paragraph which contains information from the
2366 <tt>debian/control</tt> file and other data about the
2367 source package gathered via <tt>debian/changelog</tt>
2368 and <tt>debian/rules</tt>.
2372 The fields in this file are:
2374 <list compact="compact">
2375 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2376 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2377 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2378 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2379 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2380 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2381 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2382 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2383 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2384 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2385 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2386 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2387 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2388 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2393 <sect id="controlfieldslist">
2394 <heading>List of fields</heading>
2396 <sect1 id="f-Source">
2397 <heading><tt>Source</tt></heading>
2400 This field identifies the source package name.
2404 In a main source control information, a <file>.changes</file>
2405 or a <file>.dsc</file> file this may contain only the name
2406 of the source package.
2410 In the control file of a binary package it may be followed
2411 by a version number in parentheses<footnote>
2412 It is customary to leave a space after the package name
2413 if a version number is specified.
2415 This version number may be omitted (and is, by
2416 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2417 the <tt>Version</tt> field of the binary package in
2418 question. The field itself may be omitted from a binary
2419 package control file when the source package has the same
2420 name and version as the binary package.
2424 <sect1 id="f-Maintainer">
2425 <heading><tt>Maintainer</tt></heading>
2428 The package maintainer's name and email address. The name
2429 should come first, then the email address inside angle
2430 brackets <tt><></tt> (in RFC822 format).
2434 If the maintainer's name contains a full stop then the
2435 whole field will not work directly as an email address due
2436 to a misfeature in the syntax specified in RFC822; a
2437 program using this field as an address must check for this
2438 and correct the problem if necessary (for example by
2439 putting the name in round brackets and moving it to the
2440 end, and bringing the email address forward).
2444 <sect1 id="f-Changed-By">
2445 <heading><tt>Changed-By</tt></heading>
2448 The name and email address of the person who changed the
2449 said package. Usually the name of the maintainer.
2450 All the rules for the Maintainer field apply here, too.
2454 <sect1 id="f-Section">
2455 <heading><tt>Section</tt></heading>
2458 This field specifies an application area into which the package
2459 has been classified. See <ref id="subsections">.
2463 When it appears in the <file>debian/control</file> file,
2464 it gives the value for the subfield of the same name in
2465 the <tt>Files</tt> field of the <file>.changes</file> file.
2466 It also gives the default for the same field in the binary
2471 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2472 field in the control file of a binary package - use the
2473 <tt>-is</tt> (or <tt>-isp</tt>) options to achieve this effect.
2477 <sect1 id="f-Priority">
2478 <heading><tt>Priority</tt></heading>
2481 This field represents how important that it is that the user
2482 have the package installed. See <ref id="priorities">.
2486 When it appears in the <file>debian/control</file> file,
2487 it gives the value for the subfield of the same name in
2488 the <tt>Files</tt> field of the <file>.changes</file> file.
2489 It also gives the default for the same field in the binary
2494 By default, <prgn>dpkg-gencontrol</prgn> does not include this
2495 field in the control file of a binary package - use the
2496 <tt>-ip</tt> (or <tt>-isp</tt>) options to achieve this effect.
2500 <sect1 id="f-Package">
2501 <heading><tt>Package</tt></heading>
2504 The name of the binary package.
2508 Package names must consist only of lower case letters
2509 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2510 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2511 They must be at least two characters long and must start
2512 with an alphanumeric character.
2516 <sect1 id="f-Architecture">
2517 <heading><tt>Architecture</tt></heading>
2520 This is the architecture string; it is a single word for
2521 the Debian architecture. The special value <tt>all</tt>
2522 indicates that the package is architecture-independent.
2526 In the main <file>debian/control</file> file in the source
2527 package, or in the source package control file
2528 <file>.dsc</file>, a list of architectures (separated by
2529 spaces) is also allowed, as is the special value
2530 <tt>any</tt>. A list indicates that the source will build
2531 an architecture-dependent package, and will only work
2532 correctly on the listed architectures. <tt>any</tt>
2533 indicates that though the source package isn't dependent
2534 on any particular architecture and should compile fine on
2535 any one, the binary package(s) produced are not
2536 architecture-independent but will instead be specific to
2537 whatever the current build architecture is.
2541 In a <file>.changes</file> file the <tt>Architecture</tt>
2542 field lists the architecture(s) of the package(s)
2543 currently being uploaded. This will be a list; if the
2544 source for the package is being uploaded too the special
2545 entry <tt>source</tt> is also present.
2549 See <ref id="pkg-debianrules"> for information how to get the
2550 architecture for the build process.
2554 <sect1 id="f-Essential">
2555 <heading><tt>Essential</tt></heading>
2558 This is a boolean field which may occur only in the
2559 control file of a binary package or in a per-package fields
2560 paragraph of a main source control data file.
2564 If set to <tt>yes</tt> then the package management system
2565 will refuse to remove the package (upgrading and replacing
2566 it is still possible). The other possible value is <tt>no</tt>,
2567 which is the same as not having the field at all.
2572 <heading>Package interrelationship fields:
2573 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2574 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
2575 <tt>Provides</tt>, <tt>Replaces</tt>
2579 These fields describe the package's relationships with
2580 other packages. Their syntax and semantics are described
2581 in <ref id="relationships">.</p>
2584 <sect1 id="f-Standards-Version">
2585 <heading><tt>Standards-Version</tt></heading>
2588 The most recent version of the standards (the policy
2589 manual and associated texts) with which the package
2594 The version number has four components: major and minor
2595 version number and major and minor patch level. When the
2596 standards change in a way that requires every package to
2597 change the major number will be changed. Significant
2598 changes that will require work in many packages will be
2599 signaled by a change to the minor number. The major patch
2600 level will be changed for any change to the meaning of the
2601 standards, however small; the minor patch level will be
2602 changed when only cosmetic, typographical or other edits
2603 are made which neither change the meaning of the document
2604 nor affect the contents of packages.
2608 Thus only the first three components of the policy version
2609 are significant in the <em>Standards-Version</em> control
2610 field, and so either these three components or the all
2611 four components may be specified.<footnote>
2612 In the past, people specified the full version number
2613 in the Standards-Version field, for example "2.3.0.0".
2614 Since minor patch-level changes don't introduce new
2615 policy, it was thought it would be better to relax
2616 policy and only require the first 3 components to be
2617 specified, in this example "2.3.0". All four
2618 components may still be used if someone wishes to do so.
2624 <sect1 id="f-Version">
2625 <heading><tt>Version</tt></heading>
2628 The version number of a package. The format is:
2629 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2633 The three components here are:
2635 <tag><var>epoch</var></tag>
2638 This is a single (generally small) unsigned integer. It
2639 may be omitted, in which case zero is assumed. If it is
2640 omitted then the <var>upstream_version</var> may not
2645 It is provided to allow mistakes in the version numbers
2646 of older versions of a package, and also a package's
2647 previous version numbering schemes, to be left behind.
2651 <tag><var>upstream_version</var></tag>
2654 This is the main part of the version number. It is
2655 usually the version number of the original ("upstream")
2656 package from which the <file>.deb</file> file has been made,
2657 if this is applicable. Usually this will be in the same
2658 format as that specified by the upstream author(s);
2659 however, it may need to be reformatted to fit into the
2660 package management system's format and comparison
2665 The comparison behavior of the package management system
2666 with respect to the <var>upstream_version</var> is
2667 described below. The <var>upstream_version</var>
2668 portion of the version number is mandatory.
2672 The <var>upstream_version</var> may contain only
2673 alphanumerics<footnote>
2674 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2676 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2677 <tt>:</tt> (full stop, plus, hyphen, colon) and should
2678 start with a digit. If there is no
2679 <var>debian_revision</var> then hyphens are not allowed;
2680 if there is no <var>epoch</var> then colons are not
2685 <tag><var>debian_revision</var></tag>
2688 This part of the version number specifies the version of
2689 the Debian package based on the upstream version. It
2690 may contain only alphanumerics and the characters
2691 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
2692 compared in the same way as the
2693 <var>upstream_version</var> is.
2697 It is optional; if it isn't present then the
2698 <var>upstream_version</var> may not contain a hyphen.
2699 This format represents the case where a piece of
2700 software was written specifically to be turned into a
2701 Debian package, and so there is only one "debianization"
2702 of it and therefore no revision indication is required.
2706 It is conventional to restart the
2707 <var>debian_revision</var> at <tt>1</tt> each time the
2708 <var>upstream_version</var> is increased.
2712 The package management system will break the version
2713 number apart at the last hyphen in the string (if there
2714 is one) to determine the <var>upstream_version</var> and
2715 <var>debian_revision</var>. The absence of a
2716 <var>debian_revision</var> compares earlier than the
2717 presence of one (but note that the
2718 <var>debian_revision</var> is the least significant part
2719 of the version number).
2726 The <var>upstream_version</var> and <var>debian_revision</var>
2727 parts are compared by the package management system using the
2732 The strings are compared from left to right.
2736 First the initial part of each string consisting entirely of
2737 non-digit characters is determined. These two parts (one of
2738 which may be empty) are compared lexically. If a difference
2739 is found it is returned. The lexical comparison is a
2740 comparison of ASCII values modified so that all the letters
2741 sort earlier than all the non-letters.
2745 Then the initial part of the remainder of each string which
2746 consists entirely of digit characters is determined. The
2747 numerical values of these two parts are compared, and any
2748 difference found is returned as the result of the comparison.
2749 For these purposes an empty string (which can only occur at
2750 the end of one or both version strings being compared) counts
2755 These two steps (comparing and removing initial non-digit
2756 strings and initial digit strings) are repeated until a
2757 difference is found or both strings are exhausted.
2761 Note that the purpose of epochs is to allow us to leave behind
2762 mistakes in version numbering, and to cope with situations
2763 where the version numbering scheme changes. It is
2764 <em>not</em> intended to cope with version numbers containing
2765 strings of letters which the package management system cannot
2766 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
2767 silly orderings (the author of this manual has heard of a
2768 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
2769 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
2770 <tt>2</tt> and so forth).
2774 <sect1 id="f-Description">
2775 <heading><tt>Description</tt></heading>
2778 In a source or binary control file, the <tt>Description</tt>
2779 field contains a description of the binary package, consisting
2780 of two parts, the synopsis or the short description, and the
2781 long description. The field's format is as follows:
2786 Description: <single line synopsis>
2787 <extended description over several lines>
2792 The lines in the extended description can have these formats:
2798 Those starting with a single space are part of a paragraph.
2799 Successive lines of this form will be word-wrapped when
2800 displayed. The leading space will usually be stripped off.
2804 Those starting with two or more spaces. These will be
2805 displayed verbatim. If the display cannot be panned
2806 horizontally, the displaying program will linewrap them "hard"
2807 (i.e., without taking account of word breaks). If it can they
2808 will be allowed to trail off to the right. None, one or two
2809 initial spaces may be deleted, but the number of spaces
2810 deleted from each line will be the same (so that you can have
2811 indenting work correctly, for example).
2815 Those containing a single space followed by a single full stop
2816 character. These are rendered as blank lines. This is the
2817 <em>only</em> way to get a blank line<footnote>
2818 Completely empty lines will not be rendered as blank lines.
2819 Instead, they will cause the parser to think you're starting
2820 a whole new record in the control file, and will therefore
2821 likely abort with an error.
2826 Those containing a space, a full stop and some more characters.
2827 These are for future expansion. Do not use them.
2833 Do not use tab characters. Their effect is not predictable.
2837 See <ref id="descriptions"> for further information on this.
2841 In a <file>.changes</file> file, the <tt>Description</tt> field
2842 contains a summary of the descriptions for the packages being
2847 The part of the field before the first newline is empty;
2848 thereafter each line has the name of a binary package and
2849 the summary description line from that binary package.
2850 Each line is indented by one space.
2855 <sect1 id="f-Distribution">
2856 <heading><tt>Distribution</tt></heading>
2859 In a <file>.changes</file> file or parsed changelog output
2860 this contains the (space-separated) name(s) of the
2861 distribution(s) where this version of the package should
2862 be installed. Valid distributions are determined by the
2863 archive maintainers.<footnote>
2864 Current distribution names are:
2865 <taglist compact="compact">
2866 <tag><em>stable</em></tag>
2868 This is the current "released" version of Debian
2869 GNU/Linux. Once the distribution is
2870 <em>stable</em> only security fixes and other
2871 major bug fixes are allowed. When changes are
2872 made to this distribution, the release number is
2873 increased (for example: 2.2r1 becomes 2.2r2 then
2877 <tag><em>unstable</em></tag>
2879 This distribution value refers to the
2880 <em>developmental</em> part of the Debian
2881 distribution tree. New packages, new upstream
2882 versions of packages and bug fixes go into the
2883 <em>unstable</em> directory tree. Download from
2884 this distribution at your own risk.
2887 <tag><em>testing</em></tag>
2889 This distribution value refers to the
2890 <em>testing</em> part of the Debian distribution
2891 tree. It receives its packages from the
2892 unstable distribution after a short time lag to
2893 ensure that there are no major issues with the
2894 unstable packages. It is less prone to breakage
2895 than unstable, but still risky. It is not
2896 possible to upload packages directly to
2900 <tag><em>frozen</em></tag>
2902 From time to time, the <em>testing</em>
2903 distribution enters a state of "code-freeze" in
2904 anticipation of release as a <em>stable</em>
2905 version. During this period of testing only
2906 fixes for existing or newly-discovered bugs will
2907 be allowed. The exact details of this stage are
2908 determined by the Release Manager.
2911 <tag><em>experimental</em></tag>
2913 The packages with this distribution value are
2914 deemed by their maintainers to be high
2915 risk. Oftentimes they represent early beta or
2916 developmental packages from various sources that
2917 the maintainers want people to try, but are not
2918 ready to be a part of the other parts of the
2919 Debian distribution tree. Download at your own
2925 You should list <em>all</em> distributions that the
2926 package should be installed into.
2930 More information is available in the Debian Developer's
2931 Reference, section "The Debian archive".
2938 <heading><tt>Date</tt></heading>
2941 This field includes the date the package was built or last edited.
2945 The value of this field is usually extracted from the
2946 <file>debian/changelog</file> file - see
2947 <ref id="dpkgchangelog">).
2951 <sect1 id="f-Format">
2952 <heading><tt>Format</tt></heading>
2955 This field specifies a format revision for the file.
2956 The most current format described in the Policy Manual
2957 is version <strong>1.5</strong>. The syntax of the
2958 format value is the same as that of a package version
2959 number except that no epoch or Debian revision is allowed
2960 - see <ref id="f-Version">.
2964 <sect1 id="f-Urgency">
2965 <heading><tt>Urgency</tt></heading>
2968 This is a description of how important it is to upgrade to
2969 this version from previous ones. It consists of a single
2970 keyword usually taking one of the values <tt>low</tt>,
2971 <tt>medium</tt> or <tt>high</tt> (not case-sensitive)
2972 followed by an optional commentary (separated by a space)
2973 which is usually in parentheses. For example:
2976 Urgency: low (HIGH for users of diversions)
2982 The value of this field is usually extracted from the
2983 <file>debian/changelog</file> file - see
2984 <ref id="dpkgchangelog">.
2988 <sect1 id="f-Changes">
2989 <heading><tt>Changes</tt></heading>
2992 This field contains the human-readable changes data, describing
2993 the differences between the last version and the current one.
2997 There should be nothing in this field before the first
2998 newline; all the subsequent lines must be indented by at
2999 least one space; blank lines must be represented by a line
3000 consiting only of a space and a full stop.
3004 The value of this field is usually extracted from the
3005 <file>debian/changelog</file> file - see
3006 <ref id="dpkgchangelog">).
3010 Each version's change information should be preceded by a
3011 "title" line giving at least the version, distribution(s)
3012 and urgency, in a human-readable way.
3016 If data from several versions is being returned the entry
3017 for the most recent version should be returned first, and
3018 entries should be separated by the representation of a
3019 blank line (the "title" line may also be followed by the
3020 representation of blank line).
3024 <sect1 id="f-Binary">
3025 <heading><tt>Binary</tt></heading>
3028 This field is a list of binary packages.
3032 When it appears in the <file>.dsc</file> file it is the list
3033 of binary packages which a source package can produce. It
3034 does not necessarily produce all of these binary packages
3035 for every architecture. The source control file doesn't
3036 contain details of which architectures are appropriate for
3037 which of the binary packages.
3041 When it appears in a <file>.changes</file> file it lists the
3042 names of the binary packages actually being uploaded.
3046 The syntax is a list of binary packages separated by
3048 A space after each comma is conventional.
3049 </footnote>. Currently the packages must be separated using
3050 only spaces in the <file>.changes</file> file.
3054 <sect1 id="f-Installed-Size">
3055 <heading><tt>Installed-Size</tt></heading>
3058 This field appears in the control files of binary
3059 packages, and in the <file>Packages</file> files. It gives
3060 the total amount of disk space required to install the
3065 The disk space is represented in kilobytes as a simple
3070 <sect1 id="f-Files">
3071 <heading><tt>Files</tt></heading>
3074 This field contains a list of files with information about
3075 each one. The exact information and syntax varies with
3076 the context. In all cases the part of the field
3077 contents on the same line as the field name is empty. The
3078 remainder of the field is one line per file, each line
3079 being indented by one space and containing a number of
3080 sub-fields separated by spaces.
3084 In the <file>.dsc</file> file, each line contains the MD5
3085 checksum, size and filename of the tar file and (if applicable)
3086 diff file which make up the remainder of the source
3088 That is, the parts which are not the <tt>.dsc</tt>.
3090 The exact forms of the filenames are described
3091 in <ref id="pkg-sourcearchives">.
3095 In the <file>.changes</file> file this contains one line per
3096 file being uploaded. Each line contains the MD5 checksum,
3097 size, section and priority and the filename.
3098 The <qref id="f-Section">section</qref>
3099 and <qref id="f-Priority">priority</qref>
3100 are the values of the corresponding fields in
3101 the main source control file. If no section or priority is
3102 specified then <tt>-</tt> should be used, though section
3103 and priority values must be specified for new packages to
3104 be installed properly.
3108 The special value <tt>byhand</tt> for the section in a
3109 <tt>.changes</tt> file indicates that the file in question
3110 is not an ordinary package file and must by installed by
3111 hand by the distribution maintainers. If the section is
3112 <tt>byhand</tt> the priority should be <tt>-</tt>.
3116 If a new Debian revision of a package is being shipped and
3117 no new original source archive is being distributed the
3118 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3119 entry for the original source archive
3120 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3121 but the <file>.changes</file> file should leave it out. In
3122 this case the original source archive on the distribution
3123 site must match exactly, byte-for-byte, the original
3124 source archive which was used to generate the
3125 <file>.dsc</file> file and diff which are being uploaded.</p>
3128 <sect1 id="f-Closes">
3129 <heading><tt>Closes</tt></heading>
3132 A space-separated list of bug report numbers that the upload
3133 governed by the .changes file closes.
3140 <heading>User-defined fields</heading>
3143 Additional user-defined fields may be added to the
3144 source package control file. Such fields will be
3145 ignored, and not copied to (for example) binary or
3146 source package control files or upload control files.
3150 If you wish to add additional unsupported fields to
3151 these output files you should use the mechanism
3156 Fields in the main source control information file with
3157 names starting <tt>X</tt>, followed by one or more of
3158 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3159 be copied to the output files. Only the part of the
3160 field name after the hyphen will be used in the output
3161 file. Where the letter <tt>B</tt> is used the field
3162 will appear in binary package control files, where the
3163 letter <tt>S</tt> is used in source package control
3164 files and where <tt>C</tt> is used in upload control
3165 (<tt>.changes</tt>) files.
3169 For example, if the main source information control file
3172 XBS-Comment: I stand between the candle and the star.
3174 then the binary and source package control files will contain the
3177 Comment: I stand between the candle and the star.
3186 <chapt id="maintainerscripts">
3187 <heading>Package maintainer scripts and installation procedure</heading>
3190 <heading>Introduction to package maintainer scripts</heading>
3193 It is possible to supply scripts as part of a package which
3194 the package management system will run for you when your
3195 package is installed, upgraded or removed.
3199 These scripts are the files <prgn>preinst</prgn>,
3200 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
3201 control area of the package. They must be proper executable
3202 files; if they are scripts (which is recommended), they must
3203 start with the usual <tt>#!</tt> convention. They should be
3204 readable and executable by anyone, and not world-writable.
3208 The package management system looks at the exit status from
3209 these scripts. It is important that they exit with a
3210 non-zero status if there is an error, so that the package
3211 management system can stop its processing. For shell
3212 scripts this means that you <em>almost always</em> need to
3213 use <tt>set -e</tt> (this is usually true when writing shell
3214 scripts, in fact). It is also important, of course, that
3215 they don't exit with a non-zero status if everything went
3220 When a package is upgraded a combination of the scripts from
3221 the old and new packages is called during the upgrade
3222 procedure. If your scripts are going to be at all
3223 complicated you need to be aware of this, and may need to
3224 check the arguments to your scripts.
3228 Broadly speaking the <prgn>preinst</prgn> is called before
3229 (a particular version of) a package is installed, and the
3230 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3231 before (a version of) a package is removed and the
3232 <prgn>postrm</prgn> afterwards.
3236 Programs called from maintainer scripts should not normally
3237 have a path prepended to them. Before installation is
3238 started, the package management system checks to see if the
3239 programs <prgn>ldconfig</prgn>,
3240 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3241 and <prgn>update-rc.d</prgn> can be found via the
3242 <tt>PATH</tt> environment variable. Those programs, and any
3243 other program that one would expect to be on the
3244 <tt>PATH</tt>, should thus be invoked without an absolute
3245 pathname. Maintainer scripts should also not reset the
3246 <tt>PATH</tt>, though they might choose to modify it by
3247 prepending or appending package-specific directories. These
3248 considerations really apply to all shell scripts.</p>
3251 <sect id="idempotency">
3252 <heading>Maintainer scripts Idempotency</heading>
3255 It is necessary for the error recovery procedures that the
3256 scripts be idempotent. This means that if it is run
3257 successfully, and then it is called again, it doesn't bomb
3258 out or cause any harm, but just ensures that everything is
3259 the way it ought to be. If the first call failed, or
3260 aborted half way through for some reason, the second call
3261 should merely do the things that were left undone the first
3262 time, if any, and exit with a success status if everything
3264 This is so that if an error occurs, the user interrupts
3265 <prgn>dpkg</prgn> or some other unforeseen circumstance
3266 happens you don't leave the user with a badly-broken
3267 package when <prgn>dpkg</prgn> attempts to repeat the
3273 <sect id="controllingterminal">
3274 <heading>Controlling terminal for maintainer scripts</heading>
3277 The maintainer scripts are guaranteed to run with a
3278 controlling terminal and can interact with the user.
3279 If they need to prompt for passwords, do full-screen
3280 interaction or something similar you should do these
3281 things to and from <file>/dev/tty</file>, since
3282 <prgn>dpkg</prgn> will at some point redirect scripts'
3283 standard input and output so that it can log the
3284 installation process. Likewise, because these scripts
3285 may be executed with standard output redirected into a
3286 pipe for logging purposes, Perl scripts should set
3287 unbuffered output by setting <tt>$|=1</tt> so that the
3288 output is printed immediately rather than being
3293 Each script should return a zero exit status for
3294 success, or a nonzero one for failure.
3298 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3303 <list compact="compact">
3305 <var>new-preinst</var> <tt>install</tt>
3308 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3311 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3314 <var>old-preinst</var> <tt>abort-upgrade</tt>
3315 <var>new-version</var>
3320 <list compact="compact">
3322 <var>postinst</var> <tt>configure</tt>
3323 <var>most-recently-configured-version</var>
3326 <var>old-postinst</var> <tt>abort-upgrade</tt>
3327 <var>new-version</var>
3330 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3331 <tt>in-favour</tt> <var>package</var>
3332 <var>new-version</var>
3335 <var>deconfigured's-postinst</var>
3336 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3337 <var>failed-install-package</var> <var>version</var>
3338 <tt>removing</tt> <var>conflicting-package</var>
3344 <list compact="compact">
3346 <var>prerm</var> <tt>remove</tt>
3349 <var>old-prerm</var> <tt>upgrade</tt>
3350 <var>new-version</var>
3353 <var>new-prerm</var> <tt>failed-upgrade</tt>
3354 <var>old-version</var>
3357 <var>conflictor's-prerm</var> <tt>remove</tt>
3358 <tt>in-favour</tt> <var>package</var>
3359 <var>new-version</var>
3362 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3363 <tt>in-favour</tt> <var>package-being-installed</var>
3364 <var>version</var> <tt>removing</tt>
3365 <var>conflicting-package</var>
3371 <list compact="compact">
3373 <var>postrm</var> <tt>remove</tt>
3376 <var>postrm</var> <tt>purge</tt>
3379 <var>old-postrm</var> <tt>upgrade</tt>
3380 <var>new-version</var>
3383 <var>new-postrm</var> <tt>failed-upgrade</tt>
3384 <var>old-version</var>
3387 <var>new-postrm</var> <tt>abort-install</tt>
3390 <var>new-postrm</var> <tt>abort-install</tt>
3391 <var>old-version</var>
3394 <var>new-postrm</var> <tt>abort-upgrade</tt>
3395 <var>old-version</var>
3398 <var>disappearer's-postrm</var> <tt>disappear</tt>
3399 <var>overwriter</var>
3400 <var>overwriter-version</var>
3406 <sect id="unpackphase">
3407 <heading>Details of unpack phase of installation or upgrade</heading>
3410 The procedure on installation/upgrade/overwrite/disappear
3411 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3412 stage of <tt>dpkg --install</tt>) is as follows. In each
3413 case, if a major error occurs (unless listed below) the
3414 actions are, in general, run backwards - this means that the
3415 maintainer scripts are run with different arguments in
3416 reverse order. These are the "error unwind" calls listed
3423 If a version of the package is already installed, call
3424 <example compact="compact">
3425 <var>old-prerm</var> upgrade <var>new-version</var>
3429 If the script runs but exits with a non-zero
3430 exit status, <prgn>dpkg</prgn> will attempt:
3431 <example compact="compact">
3432 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3434 Error unwind, for both the above cases:
3435 <example compact="compact">
3436 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3443 If a "conflicting" package is being removed at the same time:
3446 If any packages depended on that conflicting
3447 package and <tt>--auto-deconfigure</tt> is
3448 specified, call, for each such package:
3449 <example compact="compact">
3450 <var>deconfigured's-prerm</var> deconfigure \
3451 in-favour <var>package-being-installed</var> <var>version</var> \
3452 removing <var>conflicting-package</var> <var>version</var>
3455 <example compact="compact">
3456 <var>deconfigured's-postinst</var> abort-deconfigure \
3457 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3458 removing <var>conflicting-package</var> <var>version</var>
3460 The deconfigured packages are marked as
3461 requiring configuration, so that if
3462 <tt>--install</tt> is used they will be
3463 configured again if possible.
3466 To prepare for removal of the conflicting package, call:
3467 <example compact="compact">
3468 <var>conflictor's-prerm</var> remove \
3469 in-favour <var>package</var> <var>new-version</var>
3472 <example compact="compact">
3473 <var>conflictor's-postinst</var> abort-remove \
3474 in-favour <var>package</var> <var>new-version</var>
3483 If the package is being upgraded, call:
3484 <example compact="compact">
3485 <var>new-preinst</var> upgrade <var>old-version</var>
3489 Otherwise, if the package had some configuration
3490 files from a previous version installed (i.e., it
3491 is in the "configuration files only" state):
3492 <example compact="compact">
3493 <var>new-preinst</var> install <var>old-version</var>
3497 Otherwise (i.e., the package was completely purged):
3498 <example compact="compact">
3499 <var>new-preinst</var> install
3501 Error unwind actions, respectively:
3502 <example compact="compact">
3503 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3504 <var>new-postrm</var> abort-install <var>old-version</var>
3505 <var>new-postrm</var> abort-install
3513 The new package's files are unpacked, overwriting any
3514 that may be on the system already, for example any
3515 from the old version of the same package or from
3516 another package. Backups of the old files are kept
3517 temporarily, and if anything goes wrong the package
3518 management system will attempt to put them back as
3519 part of the error unwind.
3523 It is an error for a package to contain files which
3524 are on the system in another package, unless
3525 <tt>Replaces</tt> is used (see <ref id="replaces">).
3527 The following paragraph is not currently the case:
3528 Currently the <tt>- - force-overwrite</tt> flag is
3529 enabled, downgrading it to a warning, but this may not
3535 It is a more serious error for a package to contain a
3536 plain file or other kind of non-directory where another
3537 package has a directory (again, unless
3538 <tt>Replaces</tt> is used). This error can be
3539 overridden if desired using
3540 <tt>--force-overwrite-dir</tt>, but this is not
3545 Packages which overwrite each other's files produce
3546 behavior which, though deterministic, is hard for the
3547 system administrator to understand. It can easily
3548 lead to "missing" programs if, for example, a package
3549 is installed which overwrites a file from another
3550 package, and is then removed again.<footnote>
3551 Part of the problem is due to what is arguably a
3552 bug in <prgn>dpkg</prgn>.
3557 A directory will never be replaced by a symbolic link
3558 to a directory or vice versa; instead, the existing
3559 state (symlink or not) will be left alone and
3560 <prgn>dpkg</prgn> will follow the symlink if there is
3569 If the package is being upgraded, call
3570 <example compact="compact">
3571 <var>old-postrm</var> upgrade <var>new-version</var>
3575 If this fails, <prgn>dpkg</prgn> will attempt:
3576 <example compact="compact">
3577 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3579 Error unwind, for both cases:
3580 <example compact="compact">
3581 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3588 This is the point of no return - if
3589 <prgn>dpkg</prgn> gets this far, it won't back off
3590 past this point if an error occurs. This will
3591 leave the package in a fairly bad state, which
3592 will require a successful re-installation to clear
3593 up, but it's when <prgn>dpkg</prgn> starts doing
3594 things that are irreversible.
3599 Any files which were in the old version of the package
3600 but not in the new are removed.
3604 The new file list replaces the old.
3608 The new maintainer scripts replace the old.
3612 Any packages all of whose files have been overwritten
3613 during the installation, and which aren't required for
3614 dependencies, are considered to have been removed.
3615 For each such package
3618 <prgn>dpkg</prgn> calls:
3619 <example compact="compact">
3620 <var>disappearer's-postrm</var> disappear \
3621 <var>overwriter</var> <var>overwriter-version</var>
3625 The package's maintainer scripts are removed.
3628 It is noted in the status database as being in a
3629 sane state, namely not installed (any conffiles
3630 it may have are ignored, rather than being
3631 removed by <prgn>dpkg</prgn>). Note that
3632 disappearing packages do not have their prerm
3633 called, because <prgn>dpkg</prgn> doesn't know
3634 in advance that the package is going to
3641 Any files in the package we're unpacking that are also
3642 listed in the file lists of other packages are removed
3643 from those lists. (This will lobotomize the file list
3644 of the "conflicting" package if there is one.)
3648 The backup files made during installation, above, are
3654 The new package's status is now sane, and recorded as
3659 Here is another point of no return - if the
3660 conflicting package's removal fails we do not unwind
3661 the rest of the installation; the conflicting package
3662 is left in a half-removed limbo.
3667 If there was a conflicting package we go and do the
3668 removal actions (described below), starting with the
3669 removal of the conflicting package's files (any that
3670 are also in the package being installed have already
3671 been removed from the conflicting package's file list,
3672 and so do not get removed now).
3678 <sect id="configdetails"><heading>Details of configuration</heading>
3681 When we configure a package (this happens with <tt>dpkg
3682 --install</tt> and <tt>dpkg --configure</tt>), we first
3683 update any <tt>conffile</tt>s and then call:
3684 <example compact="compact">
3685 <var>postinst</var> configure <var>most-recently-configured-version</var>
3690 No attempt is made to unwind after errors during
3695 If there is no most recently configured version
3696 <prgn>dpkg</prgn> will pass a null argument; older versions
3697 of dpkg may pass <tt><unknown></tt> (including the
3698 angle brackets) in this case. Even older ones do not pass a
3699 second argument at all, under any circumstances.
3703 <sect id="removedetails"><heading>Details of removal and/or
3704 configuration purging</heading>
3709 <example compact="compact">
3710 <var>prerm</var> remove
3714 The package's files are removed (except <tt>conffile</tt>s).
3717 <example compact="compact">
3718 <var>postrm</var> remove
3723 All the maintainer scripts except the <prgn>postrm</prgn>
3728 If we aren't purging the package we stop here. Note
3729 that packages which have no <prgn>postrm</prgn> and no
3730 <tt>conffile</tt>s are automatically purged when
3731 removed, as there is no difference except for the
3732 <prgn>dpkg</prgn> status.
3736 The <tt>conffile</tt>s and any backup files
3737 (<tt>~</tt>-files, <tt>#*#</tt> files,
3738 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3742 <example compact="compact">
3743 <var>postrm</var> purge
3747 The package's file list is removed.
3751 No attempt is made to unwind after errors during
3758 <chapt id="relationships">
3759 <heading>Declaring relationships between packages</heading>
3761 <sect id="depsyntax">
3762 <heading>Syntax of relationship fields</heading>
3765 These fields all have a uniform syntax. They are a list of
3766 package names separated by commas.
3770 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3771 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3772 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3773 control file fields of the package, which declare
3774 dependencies on other packages, the package names listed may
3775 also include lists of alternative package names, separated
3776 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3777 if any one of the alternative packages is installed, that
3778 part of the dependency is considered to be satisfied.
3782 All of the fields except for <tt>Provides</tt> may restrict
3783 their applicability to particular versions of each named
3784 package. This is done in parentheses after each individual
3785 package name; the parentheses should contain a relation from
3786 the list below followed by a version number, in the format
3787 described in <ref id="f-Version">.
3791 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3792 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3793 strictly earlier, earlier or equal, exactly equal, later or
3794 equal and strictly later, respectively. The deprecated
3795 forms <tt><</tt> and <tt>></tt> were used to mean
3796 earlier/later or equal, rather than strictly earlier/later,
3797 so they should not appear in new packages (though
3798 <prgn>dpkg</prgn> still supports them).
3802 Whitespace may appear at any point in the version
3803 specification subject to the rules in <ref
3804 id="controlsyntax">, and must appear where it's necessary to
3805 disambiguate; it is not otherwise significant. For
3806 consistency and in case of future changes to
3807 <prgn>dpkg</prgn> it is recommended that a single space be
3808 used after a version relationship and before a version
3809 number; it is also conventional to put a single space after
3810 each comma, on either side of each vertical bar, and before
3811 each open parenthesis.
3815 For example, a list of dependencies might appear as:
3816 <example compact="compact">
3819 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3824 All fields that specify build-time relationships
3825 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3826 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3827 may be restricted to a certain set of architectures. This
3828 is indicated in brackets after each individual package name and
3829 the optional version specification. The brackets enclose a
3830 list of Debian architecture names separated by whitespace.
3831 Exclamation marks may be prepended to each of the names.
3832 (It is not permitted for some names to be prepended with
3833 exclamation marks and others not.) If the current Debian
3834 host architecture is not in this list and there are no
3835 exclamation marks in the list, or it is in the list with a
3836 prepended exclamation mark, the package name and the
3837 associated version specification are ignored completely for
3838 the purposes of defining the relationships.
3843 <example compact="compact">
3845 Build-Depends-Indep: texinfo
3846 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3847 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3852 Note that the binary package relationship fields such as
3853 <tt>Depends</tt> appear in one of the binary package
3854 sections of the control file, whereas the build-time
3855 relationships such as <tt>Build-Depends</tt> appear in the
3856 source package section of the control file (which is the
3861 <sect id="binarydeps">
3862 <heading>Binary Dependencies - <tt>Depends</tt>,
3863 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3864 <tt>Pre-Depends</tt>
3868 Packages can declare in their control file that they have
3869 certain relationships to other packages - for example, that
3870 they may not be installed at the same time as certain other
3871 packages, and/or that they depend on the presence of others.
3875 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3876 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3877 <tt>Conflicts</tt> control file fields.
3881 These six fields are used to declare a dependency
3882 relationship by one package on another. Except for
3883 <tt>Enhances</tt>, they appear in the depending (binary)
3884 package's control file. (<tt>Enhances</tt> appears in the
3885 recommending package's control file.)
3889 A <tt>Depends</tt> field takes effect <em>only</em> when a
3890 package is to be configured. It does not prevent a package
3891 being on the system in an unconfigured state while its
3892 dependencies are unsatisfied, and it is possible to replace
3893 a package whose dependencies are satisfied and which is
3894 properly installed with a different version whose
3895 dependencies are not and cannot be satisfied; when this is
3896 done the depending package will be left unconfigured (since
3897 attempts to configure it will give errors) and will not
3898 function properly. If it is necessary, a
3899 <tt>Pre-Depends</tt> field can be used, which has a partial
3900 effect even when a package is being unpacked, as explained
3901 in detail below. (The other three dependency fields,
3902 <tt>Recommends</tt>, <tt>Suggests</tt> and
3903 <tt>Enhances</tt>, are only used by the various front-ends
3904 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3908 For this reason packages in an installation run are usually
3909 all unpacked first and all configured later; this gives
3910 later versions of packages with dependencies on later
3911 versions of other packages the opportunity to have their
3912 dependencies satisfied.
3916 The <tt>Depends</tt> field thus allows package maintainers
3917 to impose an order in which packages should be configured.
3921 The meaning of the five dependency fields is as follows:
3923 <tag><tt>Depends</tt></tag>
3926 This declares an absolute dependency. A package will
3927 not be configured unless all of the packages listed in
3928 its <tt>Depends</tt> field have been correctly
3933 The <tt>Depends</tt> field should be used if the
3934 depended-on package is required for the depending
3935 package to provide a significant amount of
3940 The <tt>Depends</tt> field should also be used if the
3941 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3942 <prgn>postrm</prgn> scripts require the package to be
3943 present in order to run. Note, however, that the
3944 <prgn>postrm</prgn> cannot rely on any non-essential
3945 packages to be present during the <tt>purge</tt>
3949 <tag><tt>Recommends</tt></tag>
3952 This declares a strong, but not absolute, dependency.
3956 The <tt>Recommends</tt> field should list packages
3957 that would be found together with this one in all but
3958 unusual installations.
3962 <tag><tt>Suggests</tt></tag>
3964 This is used to declare that one package may be more
3965 useful with one or more others. Using this field
3966 tells the packaging system and the user that the
3967 listed packages are related to this one and can
3968 perhaps enhance its usefulness, but that installing
3969 this one without them is perfectly reasonable.
3972 <tag><tt>Enhances</tt></tag>
3974 This field is similar to Suggests but works in the
3975 opposite direction. It is used to declare that a
3976 package can enhance the functionality of another
3980 <tag><tt>Pre-Depends</tt></tag>
3983 This field is like <tt>Depends</tt>, except that it
3984 also forces <prgn>dpkg</prgn> to complete installation
3985 of the packages named before even starting the
3986 installation of the package which declares the
3987 pre-dependency, as follows:
3991 When a package declaring a pre-dependency is about to
3992 be <em>unpacked</em> the pre-dependency can be
3993 satisfied if the depended-on package is either fully
3994 configured, <em>or even if</em> the depended-on
3995 package(s) are only unpacked or half-configured,
3996 provided that they have been configured correctly at
3997 some point in the past (and not removed or partially
3998 removed since). In this case, both the
3999 previously-configured and currently unpacked or
4000 half-configured versions must satisfy any version
4001 clause in the <tt>Pre-Depends</tt> field.
4005 When the package declaring a pre-dependency is about
4006 to be <em>configured</em>, the pre-dependency will be
4007 treated as a normal <tt>Depends</tt>, that is, it will
4008 be considered satisfied only if the depended-on
4009 package has been correctly configured.
4013 <tt>Pre-Depends</tt> should be used sparingly,
4014 preferably only by packages whose premature upgrade or
4015 installation would hamper the ability of the system to
4016 continue with any upgrade that might be in progress.
4020 <tt>Pre-Depends</tt> are also required if the
4021 <prgn>preinst</prgn> script depends on the named
4022 package. It is best to avoid this situation if
4030 When selecting which level of dependency to use you should
4031 consider how important the depended-on package is to the
4032 functionality of the one declaring the dependency. Some
4033 packages are composed of components of varying degrees of
4034 importance. Such a package should list using
4035 <tt>Depends</tt> the package(s) which are required by the
4036 more important components. The other components'
4037 requirements may be mentioned as Suggestions or
4038 Recommendations, as appropriate to the components' relative
4043 <sect id="conflicts">
4044 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4047 When one binary package declares a conflict with another
4048 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4049 refuse to allow them to be installed on the system at the
4054 If one package is to be installed, the other must be removed
4055 first - if the package being installed is marked as
4056 replacing (see <ref id="replaces">) the one on the system,
4057 or the one on the system is marked as deselected, or both
4058 packages are marked <tt>Essential</tt>, then
4059 <prgn>dpkg</prgn> will automatically remove the package
4060 which is causing the conflict, otherwise it will halt the
4061 installation of the new package with an error. This
4062 mechanism is specifically designed to produce an error when
4063 the installed package is <tt>Essential</tt>, but the new
4068 A package will not cause a conflict merely because its
4069 configuration files are still installed; it must be at least
4074 A special exception is made for packages which declare a
4075 conflict with their own package name, or with a virtual
4076 package which they provide (see below): this does not
4077 prevent their installation, and allows a package to conflict
4078 with others providing a replacement for it. You use this
4079 feature when you want the package in question to be the only
4080 package providing some feature.
4084 A <tt>Conflicts</tt> entry should almost never have an
4085 "earlier than" version clause. This would prevent
4086 <prgn>dpkg</prgn> from upgrading or installing the package
4087 which declared such a conflict until the upgrade or removal
4088 of the conflicted-with package had been completed.
4092 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4096 As well as the names of actual ("concrete") packages, the
4097 package relationship fields <tt>Depends</tt>,
4098 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4099 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
4100 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4101 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4102 may mention "virtual packages".
4106 A <em>virtual package</em> is one which appears in the
4107 <tt>Provides</tt> control file field of another package.
4108 The effect is as if the package(s) which provide a
4109 particular virtual package name had been listed by name
4110 everywhere the virtual package name appears. (See also <ref
4115 If there are both concrete and virtual packages of the same
4116 name, then the dependency may be satisfied (or the conflict
4117 caused) by either the concrete package with the name in
4118 question or any other concrete package which provides the
4119 virtual package with the name in question. This is so that,
4120 for example, supposing we have
4121 <example compact="compact">
4125 and someone else releases an enhanced version of the
4126 <tt>bar</tt> package (for example, a non-US variant), they
4128 <example compact="compact">
4132 and the <tt>bar-plus</tt> package will now also satisfy the
4133 dependency for the <tt>foo</tt> package.
4137 If a dependency or a conflict has a version number attached
4138 then only real packages will be considered to see whether
4139 the relationship is satisfied (or the prohibition violated,
4140 for a conflict) - it is assumed that a real package which
4141 provides the virtual package is not of the "right" version.
4142 So, a <tt>Provides</tt> field may not contain version
4143 numbers, and the version number of the concrete package
4144 which provides a particular virtual package will not be
4145 looked at when considering a dependency on or conflict with
4146 the virtual package name.
4150 It is likely that the ability will be added in a future
4151 release of <prgn>dpkg</prgn> to specify a version number for
4152 each virtual package it provides. This feature is not yet
4153 present, however, and is expected to be used only
4158 If you want to specify which of a set of real packages
4159 should be the default to satisfy a particular dependency on
4160 a virtual package, you should list the real package as an
4161 alternative before the virtual one.
4166 <sect id="replaces"><heading>Overwriting files and replacing
4167 packages - <tt>Replaces</tt></heading>
4170 Packages can declare in their control file that they should
4171 overwrite files in certain other packages, or completely
4172 replace other packages. The <tt>Replaces</tt> control file
4173 field has these two distinct purposes.
4176 <sect1><heading>Overwriting files in other packages</heading>
4179 Firstly, as mentioned before, it is usually an error for a
4180 package to contain files which are on the system in
4185 However, if the overwriting package declares that it
4186 <tt>Replaces</tt> the one containing the file being
4187 overwritten, then <prgn>dpkg</prgn> will replace the file
4188 from the old package with that from the new. The file
4189 will no longer be listed as "owned" by the old package.
4193 If a package is completely replaced in this way, so that
4194 <prgn>dpkg</prgn> does not know of any files it still
4195 contains, it is considered to have "disappeared". It will
4196 be marked as not wanted on the system (selected for
4197 removal) and not installed. Any <tt>conffile</tt>s
4198 details noted for the package will be ignored, as they
4199 will have been taken over by the overwriting package. The
4200 package's <prgn>postrm</prgn> script will be run with a
4201 special argument to allow the package to do any final
4202 cleanup required. See <ref id="mscriptsinstact">.
4206 If an installed package, <tt>foo</tt> say, declares that
4207 it replaces another, <tt>bar</tt>, and an attempt is made
4208 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
4209 files in the <tt>bar</tt> package which would overwrite
4210 those already present in <tt>foo</tt>. This is so that
4211 you can install an older version of a package without
4216 For this usage of <tt>Replaces</tt>, virtual packages (see
4217 <ref id="virtual">) are not considered when looking at a
4218 <tt>Replaces</tt> field - the packages declared as being
4219 replaced must be mentioned by their real names.
4223 Furthermore, this usage of <tt>Replaces</tt> only takes
4224 effect when both packages are at least partially on the
4225 system at once, so that it can only happen if they do not
4226 conflict or if the conflict has been overridden.
4231 <sect1><heading>Replacing whole packages, forcing their
4235 Secondly, <tt>Replaces</tt> allows the packaging system to
4236 resolve which package should be removed when there is a
4237 conflict - see <ref id="conflicts">. This usage only
4238 takes effect when the two packages <em>do</em> conflict,
4239 so that the two usages of this field do not interfere with
4244 In this situation, the package declared as being replaced
4245 can be a virtual package, so for example, all mail
4246 transport agents (MTAs) would have the following fields in
4247 their control files:
4248 <example compact="compact">
4249 Provides: mail-transport-agent
4250 Conflicts: mail-transport-agent
4251 Replaces: mail-transport-agent
4253 ensuring that only one MTA can be installed at any one
4258 <sect id="sourcebinarydeps">
4259 <heading>Relationships between source and binary packages -
4260 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4261 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4265 Source packages that require certain binary packages to be
4266 installed or absent at the time of building the package
4267 can declare relationships to those binary packages.
4271 This is done using the <tt>Build-Depends</tt>,
4272 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4273 <tt>Build-Conflicts-Indep</tt> control file fields.
4277 Build-dependencies on "build-essential" binary packages can be
4278 omitted. Please see <ref id="pkg-relations"> for more information.
4282 The dependencies and conflicts they define must be satisfied
4283 (as defined earlier for binary packages) in order to invoke
4284 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4286 If you make "build-arch" or "binary-arch", you need
4287 Build-Depends. If you make "build-indep" or
4288 "binary-indep", you need Build-Depends and
4289 Build-Depends-Indep. If you make "build" or "binary",
4293 There is no Build-Depends-Arch; the autobuilders will
4294 only need the Build-Depends if they know how to build
4295 only build-arch and binary-arch. Anyone building the
4296 build-indep/binary-indep targets is basically assumed to
4297 be building the whole package and so installs all build
4301 The purpose of the original split, I recall, was so that
4302 the autobuilders wouldn't need to install extra packages
4303 needed only for the binary-indep targets. But without a
4304 build-arch/build-indep split, this didn't work, since
4305 most of the work is done in the build target, not in the
4311 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4313 The <tt>Build-Depends</tt> and
4314 <tt>Build-Conflicts</tt> fields must be satisfied when
4315 any of the following targets is invoked:
4316 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4317 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4318 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4320 <tag><tt>Build-Depends-Indep</tt>,
4321 <tt>Build-Conflicts-Indep</tt></tag>
4323 The <tt>Build-Depends-Indep</tt> and
4324 <tt>Build-Conflicts-Indep</tt> fields must be
4325 satisfied when any of the following targets is
4326 invoked: <tt>build</tt>, <tt>clean</tt>,
4327 <tt>build-indep</tt>, <tt>binary</tt> and
4328 <tt>binary-indep</tt>.
4338 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4341 Packages containing shared libraries must be constructed with
4342 a little care to make sure that the shared library is always
4343 available. This is especially important for packages whose
4344 shared libraries are vitally important, such as the C library
4345 (currently <tt>libc6</tt>).
4349 Packages involving shared libraries should be split up into
4350 several binary packages. This section mostly deals with how
4351 this separation is to be accomplished; rules for files within
4352 the shared library packages are in <ref id="libraries"> instead.
4355 <sect id="sharedlibs-runtime">
4356 <heading>Run-time shared libraries</heading>
4359 The run-time shared library needs to be placed in a package called
4360 <package><var>libraryname</var><var>soversion</var></package>, where
4361 <file><var>soversion</var></file> is the version number in the
4362 soname of the shared library<footnote>
4363 The soname is the shared object name: it's the thing
4364 that has to match exactly between building an executable
4365 and running it for the dynamic linker to be able run the
4366 program. For example, if the soname of the library is
4367 <file>libfoo.so.6</file>, the library package would be
4368 called <file>libfoo6</file>.
4370 Alternatively, if it would be confusing to directly append
4371 <var>soversion</var> to <var>libraryname</var> (e.g. because
4372 <var>libraryname</var> itself ends in a number), you may use
4373 <package><var>libraryname</var>-<var>soversion</var></package> and
4374 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4379 If you have several shared libraries built from the same
4380 source tree you may lump them all together into a single
4381 shared library package, provided that you change all of
4382 their sonames at once (so that you don't get filename
4383 clashes if you try to install different versions of the
4384 combined shared libraries package).
4388 The package should install the shared libraries under
4389 their normal names. For example, the <package>libgdbmg1</package>
4390 package should install <file>libgdbm.so.1.7.3</file> as
4391 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
4392 renamed or re-linked by any <prgn>prerm</prgn> or
4393 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4394 of renaming things safely without affecting running programs,
4395 and attempts to interfere with this are likely to lead to
4400 Shared libraries should not be installed executable, since
4401 the dynamic linker does not require this and trying to
4402 execute a shared library usually results in a core dump.
4406 The run-time library package should include the symbolic link that
4407 <prgn>ldconfig</prgn> would create for the shared libraries.
4408 For example, the <package>libgdbmg1</package> package should include
4409 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
4410 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
4411 linker (for example <prgn>ld.so</prgn> or
4412 <prgn>ld-linux.so.*</prgn>) can find the library between the
4413 time that <prgn>dpkg</prgn> installs it and the time that
4414 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4416 The package management system requires the library to be
4417 placed before the symbolic link pointing to it in the
4418 <file>.deb</file> file. This is so that when
4419 <prgn>dpkg</prgn> comes to install the symlink
4420 (overwriting the previous symlink pointing at an older
4421 version of the library), the new shared library is already
4422 in place. In the past, this was achieved by creating the
4423 library in the temporary packaging directory before
4424 creating the symlink. Unfortunately, this was not always
4425 effective, since the building of the tar file in the
4426 <file>.deb</file> depended on the behavior of the underlying
4427 file system. Some file systems (such as reiserfs) reorder
4428 the files so that the order of creation is forgotten.
4429 Since version 1.7.0, <prgn>dpkg</prgn>
4430 reorders the files itself as necessary when building a
4431 package. Thus it is no longer important to concern
4432 oneself with the order of file creation.
4436 <sect1 id="ldconfig">
4437 <heading><tt>ldconfig</tt></heading>
4440 Any package installing shared libraries in one of the default
4441 library directories of the dynamic linker (which are currently
4442 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4443 listed in <file>/etc/ld.so.conf</file><footnote>
4445 <list compact="compact">
4446 <item>/usr/X11R6/lib/Xaw3d</item>
4447 <item>/usr/local/lib</item>
4448 <item>/usr/lib/libc5-compat</item>
4449 <item>/lib/libc5-compat</item>
4450 <item>/usr/X11R6/lib</item>
4453 must use <prgn>ldconfig</prgn> to update the shared library
4458 The package must call <prgn>ldconfig</prgn> in the
4459 <prgn>postinst</prgn> script if the first argument is
4460 <tt>configure</tt>; the <prgn>postinst</prgn> script may
4461 optionally invoke <prgn>ldconfig</prgn> at other times. The
4462 package should call <prgn>ldconfig</prgn> in the
4463 <prgn>postrm</prgn> script if the first argument is
4464 <tt>remove</tt>. The maintainer scripts must not invoke
4465 <prgn>ldconfig</prgn> under any circumstances other than those
4466 described in this paragraph.<footnote>
4468 During install or upgrade, the preinst is called before
4469 the new files are installed, so calling "ldconfig" is
4470 pointless. The preinst of an existing package can also be
4471 called if an upgrade fails. However, this happens during
4472 the critical time when a shared libs may exist on-disk
4473 under a temporary name. Thus, it is dangerous and
4474 forbidden by current policy to call "ldconfig" at this
4479 When a package is installed or upgraded, "postinst
4480 configure" runs after the new files are safely on-disk.
4481 Since it is perfectly safe to invoke ldconfig
4482 unconditionally in a postinst, it is OK for a package to
4483 simply put ldconfig in its postinst without checking the
4484 argument. The postinst can also be called to recover from
4485 a failed upgrade. This happens before any new files are
4486 unpacked, so there is no reason to call "ldconfig" at this
4491 For a package that is being removed, prerm is
4492 called with all the files intact, so calling ldconfig is
4493 useless. The other calls to "prerm" happen in the case of
4494 upgrade at a time when all the files of the old package
4495 are on-disk, so again calling "ldconfig" is pointless.
4499 postrm, on the other hand, is called with the "remove"
4500 argument just after the files are removed, so this is the
4501 proper time to call "ldconfig" to notify the system of the
4502 fact shared libraries from the package are removed.
4503 The postrm can be called at several other times. At the
4504 time of "postrm purge", "postrm abort-install", or "postrm
4505 abort-upgrade", calling "ldconfig" is useless because the
4506 shared lib files are not on-disk. However, when "postrm"
4507 is invoked with arguments "upgrade", "failed-upgrade", or
4508 "disappear", a shared lib may exist on-disk under a
4517 <sect id="sharedlibs-runtime-progs">
4518 <heading>Run-time support programs</heading>
4521 If your package has some run-time support programs which use
4522 the shared library you must not put them in the shared
4523 library package. If you do that then you won't be able to
4524 install several versions of the shared library without
4525 getting filename clashes.
4529 Instead, either create another package for the runtime binaries
4530 (this package might typically be named
4531 <package><var>libraryname</var>-runtime</package>; note the absence
4532 of the <var>soversion</var> in the package name), or if the
4533 development package is small, include them in there.
4537 <sect id="sharedlibs-static">
4538 <heading>Static libraries</heading>
4541 The static library (<file><var>libraryname.a</var></file>)
4542 is usually provided in addition to the shared version.
4543 It is placed into the development package (see below).
4547 In some cases, it is acceptable for a library to be
4548 available in static form only; these cases include:
4550 <item>libraries for languages whose shared library support
4551 is immature or unstable</item>
4552 <item>libraries whose interfaces are in flux or under
4553 development (commonly the case when the library's
4554 major version number is zero, or where the ABI breaks
4555 across patchlevels)</item>
4556 <item>libraries which are explicitly intended to be
4557 available only in static form by their upstream
4562 <sect id="sharedlibs-dev">
4563 <heading>Development files</heading>
4566 The development files associated to a shared library need to be
4567 placed in a package called
4568 <package><var>libraryname</var><var>soversion</var>-dev</package>,
4569 or if you prefer only to support one development version at a
4570 time, <package><var>libraryname</var>-dev</package>.
4574 In case several development versions of a library exist, you may
4575 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
4576 <ref id="conflicts">) to ensure that the user only installs one
4577 development version at a time (as different development versions are
4578 likely to have the same header files in them, which would cause a
4579 filename clash if both were installed).
4583 The development package should contain a symlink for the associated
4584 shared library without a version number. For example, the
4585 <package>libgdbmg1-dev</package> package should include a symlink
4586 from <file>/usr/lib/libgdbm.so</file> to
4587 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the linker
4588 (<prgn>ld</prgn>) when compiling packages, as it will only look for
4589 <file>libgdbm.so</file> when compiling dynamically.
4593 <sect id="sharedlibs-intradeps">
4594 <heading>Dependencies between the packages of the same library</heading>
4597 Typically the development version should have an exact
4598 version dependency on the runtime library, to make sure that
4599 compilation and linking happens correctly. The
4600 <tt>${Source-Version}</tt> substitution variable can be
4601 useful for this purpose.
4605 <sect id="sharedlibs-shlibdeps">
4606 <heading>Dependencies between the library and other packages -
4607 the <tt>shlibs</tt> system</heading>
4610 If a package contains a binary or library which links to a
4611 shared library, we must ensure that when the package is
4612 installed on the system, all of the libraries needed are
4613 also installed. This requirement led to the creation of the
4614 <tt>shlibs</tt> system, which is very simple in its design:
4615 any package which <em>provides</em> a shared library also
4616 provides information on the package dependencies required to
4617 ensure the presence of this library, and any package which
4618 <em>uses</em> a shared library uses this information to
4619 determine the dependencies it requires. The files which
4620 contain the mapping from shared libraries to the necessary
4621 dependency information are called <file>shlibs</file> files.
4625 Thus, when a package is built which contains any shared
4626 libraries, it must provide a <file>shlibs</file> file for other
4627 packages to use, and when a package is built which contains
4628 any shared libraries or compiled binaries, it must run
4629 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4630 libraries used and hence the dependencies needed by this
4633 In the past, the shared libraries linked to were
4634 determined by calling <prgn>ldd</prgn>, but now
4635 <prgn>objdump</prgn> is used to do this. The only
4636 change this makes to package building is that
4637 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4638 libraries, whereas in the past this was unnecessary.
4639 The rest of this footnote explains the advantage that
4644 We say that a binary <tt>foo</tt> <em>directly</em> uses
4645 a library <tt>libbar</tt> if it is explicitly linked
4646 with that library (that is, it uses the flag
4647 <tt>-lbar</tt> during the linking stage). Other
4648 libraries that are needed by <tt>libbar</tt> are linked
4649 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4650 linker will load them automatically when it loads
4651 <tt>libbar</tt>. A package should depend on
4652 the libraries it directly uses, and the dependencies for
4653 those libraries should automatically pull in the other
4658 Unfortunately, the <prgn>ldd</prgn> program shows both
4659 the directly and indirectly used libraries, meaning that
4660 the dependencies determined included both direct and
4661 indirect dependencies. The use of <prgn>objdump</prgn>
4662 avoids this problem by determining only the directly
4667 A good example of where this helps is the following. We
4668 could update <tt>libimlib</tt> with a new version that
4669 supports a new graphics format called dgf (but retaining
4670 the same major version number). If we used the old
4671 <prgn>ldd</prgn> method, every package that uses
4672 <tt>libimlib</tt> would need to be recompiled so it
4673 would also depend on <tt>libdgf</tt> or it wouldn't run
4674 due to missing symbols. However with the new system,
4675 packages using <tt>libimlib</tt> can rely on
4676 <tt>libimlib</tt> itself having the dependency on
4677 <tt>libdgf</tt> and so they would not need rebuilding.
4683 In the following sections, we will first describe where the
4684 various <tt>shlibs</tt> files are to be found, then how to
4685 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4686 <tt>shlibs</tt> file format and how to create them if your
4687 package contains a shared library.
4691 <heading>The <tt>shlibs</tt> files present on the system</heading>
4694 There are several places where <tt>shlibs</tt> files are
4695 found. The following list gives them in the order in which
4696 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4697 one which gives the required information is used.)
4703 <p><file>debian/shlibs.local</file></p>
4706 This lists overrides for this package. Its use is
4707 described below (see <ref id="shlibslocal">).
4712 <p><file>/etc/dpkg/shlibs.override</file></p>
4715 This lists global overrides. This list is normally
4716 empty. It is maintained by the local system
4722 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4725 When packages are being built, any
4726 <file>debian/shlibs</file> files are copied into the
4727 control file area of the temporary build directory and
4728 given the name <file>shlibs</file>. These files give
4729 details of any shared libraries included in the
4731 An example may help here. Let us say that the
4732 source package <tt>foo</tt> generates two binary
4733 packages, <tt>libfoo2</tt> and
4734 <tt>foo-runtime</tt>. When building the binary
4735 packages, the two packages are created in the
4736 directories <file>debian/libfoo2</file> and
4737 <file>debian/foo-runtime</file> respectively.
4738 (<file>debian/tmp</file> could be used instead of one
4739 of these.) Since <tt>libfoo2</tt> provides the
4740 <tt>libfoo</tt> shared library, it will require a
4741 <tt>shlibs</tt> file, which will be installed in
4742 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4744 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4745 when <prgn>dpkg-shlibdeps</prgn> is run on the
4747 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4749 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4750 determine whether <tt>foo-prog</tt>'s library
4751 dependencies are satisfied by any of the libraries
4752 provided by <tt>libfoo2</tt>. For this reason,
4753 <prgn>dpkg-shlibdeps</prgn> must only be run once
4754 all of the individual binary packages'
4755 <tt>shlibs</tt> files have been installed into the
4762 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4765 These are the <file>shlibs</file> files corresponding to
4766 all of the packages installed on the system, and are
4767 maintained by the relevant package maintainers.
4772 <p><file>/etc/dpkg/shlibs.default</file></p>
4775 This file lists any shared libraries whose packages
4776 have failed to provide correct <file>shlibs</file> files.
4777 It was used when the <file>shlibs</file> setup was first
4778 introduced, but it is now normally empty. It is
4779 maintained by the <tt>dpkg</tt> maintainer.
4787 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4788 <file>shlibs</file> files</heading>
4791 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4792 <file>debian/rules</file> file. If your package contains only
4793 compiled binaries and libraries (but no scripts), you can
4794 use a command such as:
4795 <example compact="compact">
4796 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4797 debian/tmp/usr/lib/*
4799 Otherwise, you will need to explicitly list the compiled
4800 binaries and libraries.<footnote>
4801 If you are using <tt>debhelper</tt>, the
4802 <prgn>dh_shlibdeps</prgn> program will do this work for
4803 you. It will also correctly handle multi-binary
4809 This command puts the dependency information into the
4810 <file>debian/substvars</file> file, which is then used by
4811 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4812 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4813 field in the control file for this to work.
4817 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4818 done. If it does complain you might need to create your own
4819 <file>debian/shlibs.local</file> file, as explained below (see
4820 <ref id="shlibslocal">).
4824 If you have multiple binary packages, you will need to call
4825 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4826 compiled libraries or binaries. In such a case, you will
4827 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4828 utilities to specify a different <file>substvars</file> file.
4829 For more details on this and other options, see <manref
4830 name="dpkg-shlibdeps" section="1">.
4835 <heading>The <file>shlibs</file> File Format</heading>
4838 Each <file>shlibs</file> file has the same format. Lines
4839 beginning with <tt>#</tt> are considered to be comments and
4840 are ignored. Each line is of the form:
4841 <example compact="compact">
4842 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4847 We will explain this by reference to the example of the
4848 <tt>zlib1g</tt> package, which (at the time of writing)
4849 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4853 <var>library-name</var> is the name of the shared library,
4854 in this case <tt>libz</tt>. (This must match the name part
4855 of the soname, see below.)
4859 <var>soname-version-number</var> is the version part of the
4860 soname of the library. The soname is the thing that must
4861 exactly match for the library to be recognized by the
4862 dynamic linker, and is usually of the form
4863 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4864 example, <tt>libz.so.1</tt>.<footnote>
4865 This can be determined using the command
4866 <example compact="compact">
4867 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4870 The version part is the part which comes after
4871 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4875 <var>dependencies</var> has the same syntax as a dependency
4876 field in a binary package control file. It should give
4877 details of which packages are required to satisfy a binary
4878 built against the version of the library contained in the
4879 package. See <ref id="depsyntax"> for details.
4883 In our example, if the first version of the <tt>zlib1g</tt>
4884 package which contained a minor number of at least
4885 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4886 <tt>shlibs</tt> entry for this library could say:
4887 <example compact="compact">
4888 libz 1 zlib1g (>= 1:1.1.3)
4890 The version-specific dependency is to avoid warnings from
4891 the dynamic linker about using older shared libraries with
4897 <heading>Providing a <file>shlibs</file> file</heading>
4900 If your package provides a shared library, you should create
4901 a <file>shlibs</file> file following the format described above.
4902 It is usual to call this file <file>debian/shlibs</file> (but if
4903 you have multiple binary packages, you might want to call it
4904 <file>debian/shlibs.<var>package</var></file> instead). Then
4905 let <file>debian/rules</file> install it in the control area:
4906 <example compact="compact">
4907 install -m644 debian/shlibs debian/tmp/DEBIAN
4909 or, in the case of a multi-binary package:
4910 <example compact="compact">
4911 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4913 An alternative way of doing this is to create the
4914 <file>shlibs</file> file in the control area directly from
4915 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4916 file at all,<footnote>
4917 This is what <prgn>dh_makeshlibs</prgn> in the
4918 <tt>debhelper</tt> suite does.
4920 since the <file>debian/shlibs</file> file itself is ignored by
4921 <prgn>dpkg-shlibdeps</prgn>.
4925 As <prgn>dpkg-shlibdeps</prgn> reads the
4926 <file>DEBIAN/shlibs</file> files in all of the binary packages
4927 being built from this source package, all of the
4928 <file>DEBIAN/shlibs</file> files should be installed before
4929 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4934 <sect1 id="shlibslocal">
4935 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4938 This file is intended only as a <em>temporary</em> fix if
4939 your binaries or libraries depend on a library whose package
4940 does not yet provide a correct <file>shlibs</file> file.
4944 We will assume that you are trying to package a binary
4945 <tt>foo</tt>. When you try running
4946 <prgn>dpkg-shlibdeps</prgn> you get the following error
4947 message (<tt>-O</tt> displays the dependency information on
4948 <tt>stdout</tt> instead of writing it to
4949 <tt>debian/substvars</tt>, and the lines have been wrapped
4950 for ease of reading):
4951 <example compact="compact">
4952 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4953 dpkg-shlibdeps: warning: unable to find dependency
4954 information for shared library libbar (soname 1,
4955 path /usr/lib/libbar.so.1, dependency field Depends)
4956 shlibs:Depends=libc6 (>= 2.2.2-2)
4958 You can then run <prgn>ldd</prgn> on the binary to find the
4959 full location of the library concerned:
4960 <example compact="compact">
4962 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4963 libc.so.6 => /lib/libc.so.6 (0x40032000)
4964 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4966 So the <prgn>foo</prgn> binary depends on the
4967 <prgn>libbar</prgn> shared library, but no package seems to
4968 provide a <file>*.shlibs</file> file handling
4969 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4970 determine the package responsible:
4971 <example compact="compact">
4972 $ dpkg -S /usr/lib/libbar.so.1
4973 bar1: /usr/lib/libbar.so.1
4974 $ dpkg -s bar1 | grep Version
4977 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4978 is the one we are using. Now we can file a bug against the
4979 <tt>bar1</tt> package and create our own
4980 <file>debian/shlibs.local</file> to locally fix the problem.
4981 Including the following line into your
4982 <file>debian/shlibs.local</file> file:
4983 <example compact="compact">
4984 libbar 1 bar1 (>= 1.0-1)
4986 should allow the package build to work.
4990 As soon as the maintainer of <tt>bar1</tt> provides a
4991 correct <file>shlibs</file> file, you should remove this line
4992 from your <file>debian/shlibs.local</file> file. (You should
4993 probably also then have a versioned <tt>Build-Depends</tt>
4994 on <tt>bar1</tt> to help ensure that others do not have the
4995 same problem building your package.)
5004 <chapt id="opersys"><heading>The Operating System</heading>
5007 <heading>Filesystem hierarchy</heading>
5011 <heading>Filesystem Structure</heading>
5014 The location of all installed files and directories must
5015 comply with the Filesystem Hierarchy Standard (FHS),
5016 version 2.1, except where doing so would violate other
5017 terms of Debian Policy. The version of this document
5018 referred here can be found in the <tt>debian-policy</tt>
5020 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
5021 name="FHS (Debian copy)"> alongside this manual (or, if
5022 you have the <package>debian-policy</package> installed,
5024 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5025 (local copy)">). The
5026 latest version, which may be a more recent version, may
5028 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5029 Specific questions about following the standard may be
5030 asked on the <tt>debian-devel</tt> mailing list, or
5031 referred to the FHS mailing list (see the
5032 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5038 <heading>Site-specific programs</heading>
5041 As mandated by the FHS, packages must not place any
5042 files in <file>/usr/local</file>, either by putting them in
5043 the file system archive to be unpacked by <prgn>dpkg</prgn>
5044 or by manipulating them in their maintainer scripts.
5048 However, the package may create empty directories below
5049 <file>/usr/local</file> so that the system administrator knows
5050 where to place site-specific files. These directories
5051 should be removed on package removal if they are
5056 Note, that this applies only to directories <em>below</em>
5057 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5058 Packages must not create sub-directories in the directory
5059 <file>/usr/local</file> itself, except those listed in FHS,
5060 section 4.5. However, you may create directories below
5061 them as you wish. You must not remove any of the
5062 directories listed in 4.5, even if you created them.
5066 Since <file>/usr/local</file> can be mounted read-only from a
5067 remote server, these directories must be created and
5068 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5069 maintainer scripts and not be included in the
5070 <file>.deb</file> archive. These scripts must not fail if
5071 either of these operations fail.
5075 For example, the <tt>emacsen-common</tt> package could
5076 contain something like
5077 <example compact="compact">
5078 if [ ! -e /usr/local/share/emacs ]
5080 if mkdir /usr/local/share/emacs 2>/dev/null
5082 chown root:staff /usr/local/share/emacs
5083 chmod 2775 /usr/local/share/emacs
5087 in its <prgn>postinst</prgn> script, and
5088 <example compact="compact">
5089 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5090 rmdir /usr/local/share/emacs 2>/dev/null || true
5092 in the <prgn>prerm</prgn> script. (Note that this form is
5093 used to ensure that if the script is interrupted, the
5094 directory <file>/usr/local/share/emacs</file> will still be
5099 If you do create a directory in <file>/usr/local</file> for
5100 local additions to a package, you should ensure that
5101 settings in <file>/usr/local</file> take precedence over the
5102 equivalents in <file>/usr</file>.
5106 However, because <file>/usr/local</file> and its contents are
5107 for exclusive use of the local administrator, a package
5108 must not rely on the presence or absence of files or
5109 directories in <file>/usr/local</file> for normal operation.
5113 The <file>/usr/local</file> directory itself and all the
5114 subdirectories created by the package should (by default) have
5115 permissions 2775 (group-writable and set-group-id) and be
5116 owned by <tt>root.staff</tt>.
5121 <heading>The system-wide mail directory</heading>
5123 The system-wide mail directory is <file>/var/mail</file>. This
5124 directory is part of the base system and should not owned
5125 by any particular mail agents. The use of the old
5126 location <file>/var/spool/mail</file> is deprecated, even
5127 though the spool may still be physically located there.
5128 To maintain partial upgrade compatibility for systems
5129 which have <file>/var/spool/mail</file> as their physical mail
5130 spool, packages using <file>/var/mail</file> must depend on
5131 either <package>libc6</package> (>= 2.1.3-13), or on
5132 <package>base-files</package> (>= 2.2.0), or on later
5133 versions of either one of these packages.
5139 <heading>Users and groups</heading>
5142 <heading>Introduction</heading>
5144 The Debian system can be configured to use either plain or
5149 Some user ids (UIDs) and group ids (GIDs) are reserved
5150 globally for use by certain packages. Because some
5151 packages need to include files which are owned by these
5152 users or groups, or need the ids compiled into binaries,
5153 these ids must be used on any Debian system only for the
5154 purpose for which they are allocated. This is a serious
5155 restriction, and we should avoid getting in the way of
5156 local administration policies. In particular, many sites
5157 allocate users and/or local system groups starting at 100.
5161 Apart from this we should have dynamically allocated ids,
5162 which should by default be arranged in some sensible
5163 order, but the behavior should be configurable.
5167 Packages other than <tt>base-passwd</tt> must not modify
5168 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5169 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5174 <heading>UID and GID classes</heading>
5176 The UID and GID numbers are divided into classes as
5182 Globally allocated by the Debian project, the same
5183 on every Debian system. These ids will appear in
5184 the <file>passwd</file> and <file>group</file> files of all
5185 Debian systems, new ids in this range being added
5186 automatically as the <tt>base-passwd</tt> package is
5191 Packages which need a single statically allocated
5192 uid or gid should use one of these; their
5193 maintainers should ask the <tt>base-passwd</tt>
5201 Dynamically allocated system users and groups.
5202 Packages which need a user or group, but can have
5203 this user or group allocated dynamically and
5204 differently on each system, should use <tt>adduser
5205 --system</tt> to create the group and/or user.
5206 <prgn>adduser</prgn> will check for the existence of
5207 the user or group, and if necessary choose an unused
5208 id based on the ranges specified in
5209 <file>adduser.conf</file>.
5213 <tag>1000-29999:</tag>
5216 Dynamically allocated user accounts. By default
5217 <prgn>adduser</prgn> will choose UIDs and GIDs for
5218 user accounts in this range, though
5219 <file>adduser.conf</file> may be used to modify this
5224 <tag>30000-59999:</tag>
5229 <tag>60000-64999:</tag>
5232 Globally allocated by the Debian project, but only
5233 created on demand. The ids are allocated centrally
5234 and statically, but the actual accounts are only
5235 created on users' systems on demand.
5239 These ids are for packages which are obscure or
5240 which require many statically-allocated ids. These
5241 packages should check for and create the accounts in
5242 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5243 <prgn>adduser</prgn> if it has this facility) if
5244 necessary. Packages which are likely to require
5245 further allocations should have a "hole" left after
5246 them in the allocation, to give them room to
5251 <tag>65000-65533:</tag>
5259 User <tt>nobody</tt>. The corresponding gid refers
5260 to the group <tt>nogroup</tt>.
5267 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5268 not</em> be used, because it is the error return
5277 <sect id="sysvinit">
5278 <heading>System run levels and <file>init.d</file> scripts</heading>
5280 <sect1 id="/etc/init.d">
5281 <heading>Introduction</heading>
5284 The <file>/etc/init.d</file> directory contains the scripts
5285 executed by <prgn>init</prgn> at boot time and when the
5286 init state (or "runlevel") is changed (see <manref
5287 name="init" section="8">).
5291 There are at least two different, yet functionally
5292 equivalent, ways of handling these scripts. For the sake
5293 of simplicity, this document describes only the symbolic
5294 link method. However, it must not be assumed by maintainer
5295 scripts that this method is being used, and any automated
5296 manipulation of the various runlevel behaviours by
5297 maintainer scripts must be performed using
5298 <prgn>update-rc.d</prgn> as described below and not by
5299 manually installing or removing symlinks. For information
5300 on the implementation details of the other method,
5301 implemented in the <tt>file-rc</tt> package, please refer
5302 to the documentation of that package.
5306 These scripts are referenced by symbolic links in the
5307 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5308 runlevels, <prgn>init</prgn> looks in the directory
5309 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5310 execute, where <tt><var>n</var></tt> is the runlevel that
5311 is being changed to, or <tt>S</tt> for the boot-up
5316 The names of the links all have the form
5317 <file>S<var>mm</var><var>script</var></file> or
5318 <file>K<var>mm</var><var>script</var></file> where
5319 <var>mm</var> is a two-digit number and <var>script</var>
5320 is the name of the script (this should be the same as the
5321 name of the actual script in <file>/etc/init.d</file>).
5325 When <prgn>init</prgn> changes runlevel first the targets
5326 of the links whose names start with a <tt>K</tt> are
5327 executed, each with the single argument <tt>stop</tt>,
5328 followed by the scripts prefixed with an <tt>S</tt>, each
5329 with the single argument <tt>start</tt>. (The links are
5330 those in the <file>/etc/rc<var>n</var>.d</file> directory
5331 corresponding to the new runlevel.) The <tt>K</tt> links
5332 are responsible for killing services and the <tt>S</tt>
5333 link for starting services upon entering the runlevel.
5337 For example, if we are changing from runlevel 2 to
5338 runlevel 3, init will first execute all of the <tt>K</tt>
5339 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5340 all of the <tt>S</tt> prefixed scripts in that directory.
5341 The links starting with <tt>K</tt> will cause the
5342 referred-to file to be executed with an argument of
5343 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5348 The two-digit number <var>mm</var> is used to determine
5349 the order in which to run the scripts: low-numbered links
5350 have their scripts run first. For example, the
5351 <tt>K20</tt> scripts will be executed before the
5352 <tt>K30</tt> scripts. This is used when a certain service
5353 must be started before another. For example, the name
5354 server <prgn>bind</prgn> might need to be started before
5355 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5356 can set up its access lists. In this case, the script
5357 that starts <prgn>bind</prgn> would have a lower number
5358 than the script that starts <prgn>inn</prgn> so that it
5360 <example compact="compact">
5367 The two runlevels 0 (halt) and 6 (reboot) are slightly
5368 different. In these runlevels, the links with an
5369 <tt>S</tt> prefix are still called after those with a
5370 <tt>K</tt> prefix, but they too are called with the single
5371 argument <tt>stop</tt>.
5375 Also, if the script name ends <tt>.sh</tt>, the script
5376 will be sourced in runlevel <tt>S</tt> rather that being
5377 run in a forked subprocess, but will be explicitly run by
5378 <prgn>sh</prgn> in all other runlevels.
5383 <heading>Writing the scripts</heading>
5386 Packages that include daemons for system services should
5387 place scripts in <file>/etc/init.d</file> to start or stop
5388 services at boot time or during a change of runlevel.
5389 These scripts should be named
5390 <file>/etc/init.d/<var>package</var></file>, and they should
5391 accept one argument, saying what to do:
5394 <tag><tt>start</tt></tag>
5395 <item>start the service,</item>
5397 <tag><tt>stop</tt></tag>
5398 <item>stop the service,</item>
5400 <tag><tt>restart</tt></tag>
5401 <item>stop and restart the service if it's already running,
5402 otherwise start the service</item>
5404 <tag><tt>reload</tt></tag>
5405 <item><p>cause the configuration of the service to be
5406 reloaded without actually stopping and restarting
5409 <tag><tt>force-reload</tt></tag>
5410 <item>cause the configuration to be reloaded if the
5411 service supports this, otherwise restart the
5415 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5416 <tt>force-reload</tt> options should be supported by all
5417 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5422 The <file>init.d</file> scripts should ensure that they will
5423 behave sensibly if invoked with <tt>start</tt> when the
5424 service is already running, or with <tt>stop</tt> when it
5425 isn't, and that they don't kill unfortunately-named user
5426 processes. The best way to achieve this is usually to use
5427 <prgn>start-stop-daemon</prgn>.
5431 If a service reloads its configuration automatically (as
5432 in the case of <prgn>cron</prgn>, for example), the
5433 <tt>reload</tt> option of the <file>init.d</file> script
5434 should behave as if the configuration has been reloaded
5439 The <file>/etc/init.d</file> scripts must be treated as
5440 configuration files, either (if they are present in the
5441 package, that is, in the .deb file) by marking them as
5442 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
5443 by managing them correctly in the maintainer scripts (see
5444 <ref id="config-files">). This is important since we want
5445 to give the local system administrator the chance to adapt
5446 the scripts to the local system, e.g., to disable a
5447 service without de-installing the package, or to specify
5448 some special command line options when starting a service,
5449 while making sure her changes aren't lost during the next
5454 These scripts should not fail obscurely when the
5455 configuration files remain but the package has been
5456 removed, as configuration files remain on the system after
5457 the package has been removed. Only when <prgn>dpkg</prgn>
5458 is executed with the <tt>--purge</tt> option will
5459 configuration files be removed. In particular, as the
5460 <file>/etc/init.d/<var>package</var></file> script itself is
5461 usually a <tt>conffile</tt>, it will remain on the system
5462 if the package is removed but not purged. Therefore, you
5463 should include a <tt>test</tt> statement at the top of the
5465 <example compact="compact">
5466 test -f <var>program-executed-later-in-script</var> || exit 0
5471 Often there are some variables in the <file>init.d</file>
5472 scripts whose values control the behaviour of the scripts,
5473 and which a system administrator is likely to want to
5474 change. As the scripts themselves are frequently
5475 <tt>conffile</tt>s, modifying them requires that the
5476 administrator merge in their changes each time the package
5477 is upgraded and the <tt>conffile</tt> changes. To ease
5478 the burden on the system administrator, such configurable
5479 values should not be placed directly in the script.
5480 Instead, they should be placed in a file in
5481 <file>/etc/default</file>, which typically will have the same
5482 base name as the <file>init.d</file> script. This extra file
5483 should be sourced by the script when the script runs. It
5484 must contain only variable settings and comments in POSIX
5485 <prgn>sh</prgn> format. It may either be a
5486 <tt>conffile</tt> or a configuration file maintained by
5487 the package maintainer scripts. See <ref id="config-files">
5492 To ensure that vital configurable values are always
5493 available, the <file>init.d</file> script should set default
5494 values for each of the shell variables it uses, either
5495 before sourcing the <file>/etc/default/</file> file or
5496 afterwards using something like the <tt>:
5497 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
5498 script must behave sensibly and not fail if the
5499 <file>/etc/default</file> file is deleted.
5504 <heading>Interfacing with the initscript system</heading>
5507 Maintainers should use the abstraction layer provided by
5508 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
5509 programs to deal with initscripts in their packages'
5510 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
5511 and <prgn>postrm</prgn>.
5515 Directly managing the /etc/rc?.d links and directly
5516 invoking the <file>/etc/init.d/</file> initscripts should
5517 be done only by packages providing the initscript
5518 subsystem (such as <prgn>sysvinit</prgn> and
5519 <prgn>file-rc</prgn>).
5523 <heading>Managing the links</heading>
5526 The program <prgn>update-rc.d</prgn> is provided for
5527 package maintainers to arrange for the proper creation and
5528 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
5529 or their functional equivalent if another method is being
5530 used. This may be used by maintainers in their packages'
5531 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
5535 You must not include any <file>/etc/rc<var>n</var>.d</file>
5536 symbolic links in the actual archive or manually create or
5537 remove the symbolic links in maintainer scripts; you must
5538 use the <prgn>update-rc.d</prgn> program instead. (The
5539 former will fail if an alternative method of maintaining
5540 runlevel information is being used.) You must not include
5541 the <file>/etc/rc<var>n</var>.d</file> directories themselves
5542 in the archive either. (Only the <tt>sysvinit</tt>
5547 By default <prgn>update-rc.d</prgn> will start services in
5548 each of the multi-user state runlevels (2, 3, 4, and 5)
5549 and stop them in the halt runlevel (0), the single-user
5550 runlevel (1) and the reboot runlevel (6). The system
5551 administrator will have the opportunity to customize
5552 runlevels by simply adding, moving, or removing the
5553 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
5554 symbolic links are being used, or by modifying
5555 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
5560 To get the default behavior for your package, put in your
5561 <prgn>postinst</prgn> script
5562 <example compact="compact">
5563 update-rc.d <var>package</var> defaults
5565 and in your <prgn>postrm</prgn>
5566 <example compact="compact">
5567 if [ "$1" = purge ]; then
5568 update-rc.d <var>package</var> remove
5570 </example>. Note that if your package changes runlevels
5571 or priority, you may have to remove and recreate the links,
5572 since otherwise the old links may persist. Refer to the
5573 documentation of <prgn>update-rc.d</prgn>.
5577 This will use a default sequence number of 20. If it does
5578 not matter when or in which order the <file>init.d</file>
5579 script is run, use this default. If it does, then you
5580 should talk to the maintainer of the <prgn>sysvinit</prgn>
5581 package or post to <tt>debian-devel</tt>, and they will
5582 help you choose a number.
5586 For more information about using <tt>update-rc.d</tt>,
5587 please consult its manpage <manref name="update-rc.d"
5593 <heading>Running initscripts</heading>
5595 The program <prgn>invoke-rc.d</prgn> is provided to make
5596 it easier for package maintainers to properly invoke an
5597 initscript, obeying runlevel and other locally-defined
5598 constraints that might limit a package's right to start,
5599 stop and otherwise manage services. This program may be
5600 used by maintainers in their packages' scripts.
5604 The use of <prgn>invoke-rc.d</prgn> to invoke the
5605 <file>/etc/init.d/*</file> initscripts is strongly
5606 recommended<footnote>
5607 In the future, the use of invoke-rc.d to invoke
5608 initscripts shall be made mandatory. Maintainers are
5609 advised to switch to invoke-rc.d as soon as
5611 </footnote>, instead of calling them directly.
5615 By default, <prgn>invoke-rc.d</prgn> will pass any
5616 action requests (start, stop, reload, restart...) to the
5617 <file>/etc/init.d</file> script, filtering out requests
5618 to start or restart a service out of its intended
5623 Most packages will simply need to change:
5624 <example compact="compact">/etc/init.d/<package>
5625 <action></example> in their <prgn>postinst</prgn>
5626 and <prgn>prerm</prgn> scripts to:
5627 <example compact="compact">
5628 if [ -x /usr/sbin/invoke-rc.d ] ; then
5629 invoke-rc.d <var>package</var> <action>
5631 /etc/init.d/<var>package</var> <action>
5637 A package should register its initscript services using
5638 <prgn>update-rc.d</prgn> before it tries to invoke them
5639 using <prgn>invoke-rc.d</prgn>. Invocation of
5640 unregistered services may fail.
5644 For more information about using
5645 <prgn>invoke-rc.d</prgn>, please consult its manpage
5646 <manref name="invoke-rc.d" section="8">.
5652 <heading>Boot-time initialization</heading>
5655 There used to be another directory, <file>/etc/rc.boot</file>,
5656 which contained scripts which were run once per machine
5657 boot. This has been deprecated in favour of links from
5658 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5659 described in <ref id="/etc/init.d">. Packages must not
5660 place files in <file>/etc/rc.boot</file>.
5665 <heading>Example</heading>
5668 The <prgn>bind</prgn> DNS (nameserver) package wants to
5669 make sure that the nameserver is running in multiuser
5670 runlevels, and is properly shut down with the system. It
5671 puts a script in <file>/etc/init.d</file>, naming the script
5672 appropriately <tt>bind</tt>. As you can see, the script
5673 interprets the argument <tt>reload</tt> to send the
5674 nameserver a <tt>HUP</tt> signal (causing it to reload its
5675 configuration); this way the system administrator can say
5676 <tt>/etc/init.d/bind reload</tt> to reload the name
5677 server. The script has one configurable value, which can
5678 be used to pass parameters to the named program at
5679 startup; this value is read from
5680 <file>/etc/default/bind</file> (see below).
5684 <example compact="compact">
5687 # Original version by Robert Leslie
5688 # <rob@mars.org>, edited by iwj and cs
5690 test -x /usr/sbin/named || exit 0
5692 # Source defaults file.
5694 if [ -f /etc/default/bind ]; then
5701 echo -n "Starting domain name service: named"
5702 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5707 echo -n "Stopping domain name service: named"
5708 start-stop-daemon --stop --quiet \
5709 --pidfile /var/run/named.pid --exec /usr/sbin/named
5713 echo -n "Restarting domain name service: named"
5714 start-stop-daemon --stop --quiet \
5715 --pidfile /var/run/named.pid --exec /usr/sbin/named
5716 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5720 force-reload|reload)
5721 echo -n "Reloading configuration of domain name service: named"
5722 start-stop-daemon --stop --signal 1 --quiet \
5723 --pidfile /var/run/named.pid --exec /usr/sbin/named
5727 echo "Usage: /etc/init.d/bind " \
5728 " {start|stop|restart|reload|force-reload}" >&2
5738 Complementing the above init script is a configuration
5739 file <file>/etc/default/bind</file>, which contains
5740 configurable parameters used by the script. This would be
5741 created by the <prgn>postinst</prgn> script if it was not
5742 already present, and removed on purge by the
5743 <prgn>postrm</prgn> script.
5744 <example compact="compact">
5745 # Specified parameters to pass to named. See named(8).
5746 # You may uncomment the following line, and edit to taste.
5752 Another example on which you can base your
5753 <file>/etc/init.d</file> scripts is found in
5754 <file>/etc/init.d/skeleton</file>.
5758 If this package is happy with the default setup from
5759 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5760 and having named running in all runlevels, it can say in
5761 its <prgn>postinst</prgn>:
5762 <example compact="compact">
5763 update-rc.d bind defaults >/dev/null
5765 And in its <prgn>postrm</prgn>, to remove the links when the
5767 <example compact="compact">
5768 if [ "$1" = purge ]; then
5769 update-rc.d bind remove >/dev/null
5777 <heading>Console messages from <file>init.d</file> scripts</heading>
5780 This section describes the formats to be used for messages
5781 written to standard output by the <file>/etc/init.d</file>
5782 scripts. The intent is to improve the consistency of
5783 Debian's startup and shutdown look and feel. For this
5784 reason, please look very carefully at the details. We want
5785 the messages to have the same format in terms of wording,
5786 spaces, punctuation and case of letters.
5790 Here is a list of overall rules that you should use when you
5791 create output messages. They can be useful if you have a
5792 non-standard message that is not covered specifically in the
5799 Every message should fit in one line (fewer than 80
5800 characters), start with a capital letter and end with
5801 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5805 If you want to express that the computer is working on
5806 something (that is, performing a specific task, not
5807 starting or stopping a program), we use an "ellipsis"
5808 (three dots: <tt>...</tt>). Note that we don't insert
5809 spaces before or after the dots. If the task has been
5810 completed we write <tt>done.</tt> and a line feed.
5814 Design your messages as if the computer is telling you
5815 what he is doing (let him be polite :-), but don't
5816 mention "him" directly. For example, if you think of
5818 <example compact="compact">
5819 I'm starting network daemons: nfsd mountd.
5822 <example compact="compact">
5823 Starting network daemons: nfsd mountd.
5830 There are standard message formats for the following
5831 situations. They should be used by the <tt>init.d</tt>
5838 <p>When daemons are started</p>
5841 If your script starts one or more daemons, the output
5842 should look like this (a single line, no leading
5844 <example compact="compact">
5845 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5847 The <var>description</var> should describe the
5848 subsystem the daemon or set of daemons are part of,
5849 while <var>daemon-1</var> up to <var>daemon-n</var>
5850 denote each daemon's name (typically the file name of
5855 For example, the output of <file>/etc/init.d/lpd</file>
5857 <example compact="compact">
5858 Starting printer spooler: lpd.
5863 This can be achieved by saying
5864 <example compact="compact">
5865 echo -n "Starting printer spooler: lpd"
5866 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5869 in the script. If you have more than one daemon to
5870 start, you should do the following:
5871 <example compact="compact">
5872 echo -n "Starting remote file system services:"
5873 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5874 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5875 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5878 This makes it possible for the user to see what takes
5879 so long and when the final daemon has been started.
5880 You should be careful where to put spaces: in the
5881 example above the system administrator can easily
5882 comment out a line if he don't wants to start a
5883 specific daemon, while the displayed message still
5889 <p>When a system parameter is being set</p>
5892 If you have to set up different system parameters
5893 during the system boot, you should use this format:
5894 <example compact="compact">
5895 Setting <var>parameter</var> to "<var>value</var>".
5900 You can use a statement such as the following to get
5902 <example compact="compact">
5903 echo "Setting DNS domainname to \"$domainname\"."
5908 Note that the same symbol (<tt>"</tt>) is used for the left
5909 and right quotation marks. A grave accent (<tt>`</tt>) is
5910 not a quote character; neither is an apostrophe
5916 <p>When a daemon is stopped or restarted</p>
5919 When you stop or restart a daemon, you should issue a
5920 message identical to the startup message, except that
5921 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5922 or <tt>Restarting</tt> respectively.
5926 For example, stopping the printer daemon will like
5928 <example compact="compact">
5929 Stopping printer spooler: lpd.
5935 <p>When something is executed</p>
5938 There are several examples where you have to run a
5939 program at system startup or shutdown to perform a
5940 specific task, for example, setting the system's clock
5941 using <prgn>netdate</prgn> or killing all processes
5942 when the system shuts down. Your message should look
5944 <example compact="compact">
5945 Doing something very useful...done.
5947 You should print the <tt>done.</tt> immediately after
5948 the job has been completed, so that the user is
5949 informed why she has to wait. You can get this
5951 <example compact="compact">
5952 echo -n "Doing something very useful..."
5961 <p>When the configuration is reloaded</p>
5964 When a daemon is forced to reload its configuration
5965 files you should use the following format:
5966 <example compact="compact">
5967 Reloading <var>description</var> configuration...done.
5969 where <var>description</var> is the same as in the
5970 daemon starting message.
5978 <heading>Cron jobs</heading>
5981 Packages must not modify the configuration file
5982 <file>/etc/crontab</file>, and they must not modify the files in
5983 <file>/var/spool/cron/crontabs</file>.</p>
5986 If a package wants to install a job that has to be executed
5987 via cron, it should place a file with the name of the
5988 package in one or more of the following directories:
5989 <example compact="compact">
5994 As these directory names imply, the files within them are
5995 executed on a daily, weekly, or monthly basis,
5996 respectively. The exact times are listed in
5997 <file>/etc/crontab</file>.</p>
6000 All files installed in any of these directories must be
6001 scripts (e.g., shell scripts or Perl scripts) so that they
6002 can easily be modified by the local system administrator.
6003 In addition, they should be treated as configuration
6008 If a certain job has to be executed more frequently than
6009 daily, the package should install a file
6010 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6011 same syntax as <file>/etc/crontab</file> and is processed by
6012 <prgn>cron</prgn> automatically. The file must also be
6013 treated as a configuration file. (Note that entries in the
6014 <file>/etc/cron.d</file> directory are not handled by
6015 <prgn>anacron</prgn>. Thus, you should only use this
6016 directory for jobs which may be skipped if the system is not
6020 The scripts or crontab entries in these directories should
6021 check if all necessary programs are installed before they
6022 try to execute them. Otherwise, problems will arise when a
6023 package was removed but not purged since configuration files
6024 are kept on the system in this situation.</p>
6028 <heading>Menus</heading>
6031 The Debian <tt>menu</tt> package provides a standard
6032 interface between packages providing applications and
6033 documents, and <em>menu programs</em> (either X window
6034 managers or text-based menu programs such as
6035 <prgn>pdmenu</prgn>).
6039 All packages that provide applications that need not be
6040 passed any special command line arguments for normal
6041 operation should register a menu entry for those
6042 applications, so that users of the <tt>menu</tt> package
6043 will automatically get menu entries in their window
6044 managers, as well in shells like <tt>pdmenu</tt>.
6048 Menu entries should follow the current menu policy.
6052 The menu policy can be found in the <tt>menu-policy</tt>
6053 files in the <tt>debian-policy</tt> package.
6054 It is also available from the Debian web mirrors at
6055 <tt><url name="/doc/packaging-manuals/menu-policy/"
6056 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
6057 and from the Debian archive mirrors at
6058 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
6059 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
6063 Please also refer to the <em>Debian Menu System</em>
6064 documentation that comes with the <tt>menu</tt> package for
6065 information about how to register your applications and web
6071 <heading>Multimedia handlers</heading>
6074 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6075 is a mechanism for encoding files and data streams and
6076 providing meta-information about them, in particular their
6077 type (e.g. audio or video) and format (e.g. PNG, HTML,
6082 Registration of MIME type handlers allows programs like mail
6083 user agents and web browsers to to invoke these handlers to
6084 view, edit or display MIME types they don't support
6089 Packages which provide the ability to view/show/play,
6090 compose, edit or print MIME types should register themselves
6091 as such following the current MIME support policy.
6095 The MIME support policy can be found in the <tt>mime-policy</tt>
6096 files in the <tt>debian-policy</tt> package.
6097 It is also available from the Debian web mirrors at
6098 <tt><url name="/doc/packaging-manuals/mime-policy/"
6099 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
6100 and from the Debian archive mirrors at
6101 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
6102 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
6108 <heading>Keyboard configuration</heading>
6111 To achieve a consistent keyboard configuration so that all
6112 applications interpret a keyboard event the same way, all
6113 programs in the Debian distribution must be configured to
6114 comply with the following guidelines.
6118 The following keys must have the specified interpretations:
6121 <tag><tt><--</tt></tag>
6122 <item>delete the character to the left of the cursor</item>
6124 <tag><tt>Delete</tt></tag>
6125 <item>delete the character to the right of the cursor</item>
6127 <tag><tt>Control+H</tt></tag>
6128 <item>emacs: the help prefix</item>
6131 The interpretation of any keyboard events should be
6132 independent of the terminal that is used, be it a virtual
6133 console, an X terminal emulator, an rlogin/telnet session,
6138 The following list explains how the different programs
6139 should be set up to achieve this:
6145 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6149 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6153 X translations are set up to make
6154 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6155 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6156 is the vt220 escape code for the "delete character"
6157 key). This must be done by loading the X resources
6158 using <prgn>xrdb</prgn> on all local X displays, not
6159 using the application defaults, so that the
6160 translation resources used correspond to the
6161 <prgn>xmodmap</prgn> settings.
6165 The Linux console is configured to make
6166 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6167 generate <tt>ESC [ 3 ~</tt>.
6171 X applications are configured so that <tt><</tt>
6172 deletes left, and <tt>Delete</tt> deletes right. Motif
6173 applications already work like this.
6177 Terminals should have <tt>stty erase ^?</tt> .
6181 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6182 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6183 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6187 Emacs is programmed to map <tt>KB_Backspace</tt> or
6188 the <tt>stty erase</tt> character to
6189 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6190 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6191 <tt>^H</tt> to <tt>help</tt> as always.
6195 Other applications use the <tt>stty erase</tt>
6196 character and <tt>kdch1</tt> for the two delete keys,
6197 with ASCII DEL being "delete previous character" and
6198 <tt>kdch1</tt> being "delete character under
6206 This will solve the problem except for the following
6213 Some terminals have a <tt><--</tt> key that cannot
6214 be made to produce anything except <tt>^H</tt>. On
6215 these terminals Emacs help will be unavailable on
6216 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6217 character takes precedence in Emacs, and has been set
6218 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6219 available) can be used instead.
6223 Some operating systems use <tt>^H</tt> for <tt>stty
6224 erase</tt>. However, modern telnet versions and all
6225 rlogin versions propagate <tt>stty</tt> settings, and
6226 almost all UNIX versions honour <tt>stty erase</tt>.
6227 Where the <tt>stty</tt> settings are not propagated
6228 correctly, things can be made to work by using
6229 <tt>stty</tt> manually.
6233 Some systems (including previous Debian versions) use
6234 <prgn>xmodmap</prgn> to arrange for both
6235 <tt><--</tt> and <tt>Delete</tt> to generate
6236 <tt>KB_Delete</tt>. We can change the behavior of
6237 their X clients using the same X resources that we use
6238 to do it for our own clients, or configure our clients
6239 using their resources when things are the other way
6240 around. On displays configured like this
6241 <tt>Delete</tt> will not work, but <tt><--</tt>
6246 Some operating systems have different <tt>kdch1</tt>
6247 settings in their <tt>terminfo</tt> database for
6248 <tt>xterm</tt> and others. On these systems the
6249 <tt>Delete</tt> key will not work correctly when you
6250 log in from a system conforming to our policy, but
6251 <tt><--</tt> will.
6258 <heading>Environment variables</heading>
6261 A program must not depend on environment variables to get
6262 reasonable defaults. (That's because these environment
6263 variables would have to be set in a system-wide
6264 configuration file like <file>/etc/profile</file>, which is not
6265 supported by all shells.)
6269 If a program usually depends on environment variables for its
6270 configuration, the program should be changed to fall back to
6271 a reasonable default configuration if these environment
6272 variables are not present. If this cannot be done easily
6273 (e.g., if the source code of a non-free program is not
6274 available), the program must be replaced by a small
6275 "wrapper" shell script which sets the environment variables
6276 if they are not already defined, and calls the original program.
6280 Here is an example of a wrapper script for this purpose:
6282 <example compact="compact">
6284 BAR=${BAR:-/var/lib/fubar}
6286 exec /usr/lib/foo/foo "$@"
6291 Furthermore, as <file>/etc/profile</file> is a configuration
6292 file of the <prgn>base-files</prgn> package, other packages must
6293 not put any environment variables or other commands into that
6302 <heading>Files</heading>
6305 <heading>Binaries</heading>
6308 Two different packages must not install programs with
6309 different functionality but with the same filenames. (The
6310 case of two programs having the same functionality but
6311 different implementations is handled via "alternatives" or
6312 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6313 <ref id="conflicts"> respectively.) If this case happens,
6314 one of the programs must be renamed. The maintainers should
6315 report this to the <tt>debian-devel</tt> mailing list and
6316 try to find a consensus about which program will have to be
6317 renamed. If a consensus cannot be reached, <em>both</em>
6318 programs must be renamed.
6322 By default, when a package is being built, any binaries
6323 created should include debugging information, as well as
6324 being compiled with optimization. You should also turn on
6325 as many reasonable compilation warnings as possible; this
6326 makes life easier for porters, who can then look at build
6327 logs for possible problems. For the C programming language,
6328 this means the following compilation parameters should be
6330 <example compact="compact">
6332 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6334 install -s # (or use strip on the files in debian/tmp)
6339 Note that by default all installed binaries should be stripped,
6340 either by using the <tt>-s</tt> flag to
6341 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6342 the binaries after they have been copied into
6343 <file>debian/tmp</file> but before the tree is made into a
6348 Although binaries in the build tree should be compiled with
6349 debugging information by default, it can often be difficult
6350 to debug programs if they are also subjected to compiler
6351 optimization. For this reason, it is recommended to support
6352 the standardized environment
6353 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
6354 contain several flags to change how a package is compiled
6362 The presence of this string means that the package
6363 should be compiled with a minimum of optimization.
6364 For C programs, it is best to add <tt>-O0</tt>
6365 to <tt>CFLAGS</tt> (although this is usually the
6366 default). Some programs might fail to build or run at
6367 this level of optimization; it may be necessary to
6368 use <tt>-O1</tt>, for example.
6372 This string means that the debugging symbols should
6373 not be stripped from the binary during installation,
6374 so that debugging information may be included in the package.
6380 The following makefile snippet is an example of how one may
6381 implement the build options; you will probably have to
6382 massage this example in order to make it work for your
6384 <example compact="compact">
6387 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
6388 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
6389 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
6390 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
6392 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
6397 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
6398 INSTALL_PROGRAM += -s
6404 It is up to the package maintainer to decide what
6405 compilation options are best for the package. Certain
6406 binaries (such as computationally-intensive programs) will
6407 function better with certain flags (<tt>-O3</tt>, for
6408 example); feel free to use them. Please use good judgment
6409 here. Don't use flags for the sake of it; only use them
6410 if there is good reason to do so. Feel free to override
6411 the upstream author's ideas about which compilation
6412 options are best: they are often inappropriate for our
6418 <sect id="libraries">
6419 <heading>Libraries</heading>
6422 The shared version of a library must be compiled with
6423 <tt>-fPIC</tt>, and the static version must not be. In other
6424 words, each source unit (<tt>*.c</tt>, for example, for C files)
6425 will need to be compiled twice.
6429 You must specify the gcc option <tt>-D_REENTRANT</tt>
6430 when building a library (either static or shared) to make
6431 the library compatible with LinuxThreads.
6435 All installed shared libraries should be stripped with
6436 <example compact="compact">
6437 strip --strip-unneeded <var>your-lib</var>
6439 (The option <tt>--strip-unneeded</tt> makes
6440 <prgn>strip</prgn> remove only the symbols which aren't
6441 needed for relocation processing.) Shared libraries can
6442 function perfectly well when stripped, since the symbols for
6443 dynamic linking are in a separate part of the ELF object
6445 You might also want to use the options
6446 <tt>--remove-section=.comment</tt> and
6447 <tt>--remove-section=.note</tt> on both shared libraries
6448 and executables, and <tt>--strip-debug</tt> on static
6454 Note that under some circumstances it may be useful to
6455 install a shared library unstripped, for example when
6456 building a separate package to support debugging.
6460 Shared object files (often <file>.so</file> files) that are not
6461 public libraries, that is, they are not meant to be linked
6462 to by third party executables (binaries of other packages),
6463 should be installed in subdirectories of the
6464 <file>/usr/lib</file> directory. Such files are exempt from the
6465 rules that govern ordinary shared libraries, except that
6466 they must not be installed executable and should be
6468 A common example are the so-called "plug-ins",
6469 internal shared objects that are dynamically loaded by
6470 programs using <manref name="dlopen" section="3">.
6475 Packages containing shared libraries that may be linked to
6476 by other packages' binaries, but which for some
6477 <em>compelling</em> reason can not be installed in
6478 <file>/usr/lib</file> directory, may install the shared library
6479 files in subdirectories of the <file>/usr/lib</file> directory,
6480 in which case they should arrange to add that directory in
6481 <file>/etc/ld.so.conf</file> in the package's post-installation
6482 script, and remove it in the package's post-removal script.
6486 An ever increasing number of packages are using
6487 <prgn>libtool</prgn> to do their linking. The latest GNU
6488 libtools (>= 1.3a) can take advantage of the metadata in the
6489 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6490 files). The main advantage of <prgn>libtool</prgn>'s
6491 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6492 store and subsequently access metadata with respect to the
6493 libraries it builds. <prgn>libtool</prgn> will search for
6494 those files, which contain a lot of useful information about
6495 a library (such as library dependency information for static
6496 linking). Also, they're <em>essential</em> for programs
6497 using <tt>libltdl</tt>.<footnote>
6498 Although <prgn>libtool</prgn> is fully capable of
6499 linking against shared libraries which don't have
6500 <tt>.la</tt> files, as it is a mere shell script it can
6501 add considerably to the build time of a
6502 <prgn>libtool</prgn>-using package if that shell script
6503 has to derive all this information from first principles
6504 for each library every time it is linked. With the
6505 advent of <prgn>libtool</prgn> version 1.4 (and to a
6506 lesser extent <prgn>libtool</prgn> version 1.3), the
6507 <file>.la</file> files also store information about
6508 inter-library dependencies which cannot necessarily be
6509 derived after the <file>.la</file> file is deleted.
6514 Packages that use <prgn>libtool</prgn> to create shared
6515 libraries should include the <file>.la</file> files in the
6516 <tt>-dev</tt> package, unless the package relies on
6517 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
6518 the <tt>.la</tt> files must go in the run-time library
6523 You must make sure that you use only released versions of
6524 shared libraries to build your packages; otherwise other
6525 users will not be able to run your binaries
6526 properly. Producing source packages that depend on
6527 unreleased compilers is also usually a bad
6534 <heading>Shared libraries</heading>
6536 This section has moved to <ref id="sharedlibs">.
6542 <heading>Scripts</heading>
6545 All command scripts, including the package maintainer
6546 scripts inside the package and used by <prgn>dpkg</prgn>,
6547 should have a <tt>#!</tt> line naming the shell to be used
6552 In the case of Perl scripts this should be
6553 <tt>#!/usr/bin/perl</tt>.
6557 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
6558 should almost certainly start with <tt>set -e</tt> so that
6559 errors are detected. Every script should use
6560 <tt>set -e</tt> or check the exit status of <em>every</em>
6565 The standard shell interpreter <file>/bin/sh</file> can be a
6566 symbolic link to any POSIX compatible shell, if <tt>echo
6567 -n</tt> does not generate a newline.<footnote>
6568 Debian policy specifies POSIX behavior for
6569 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
6570 use in the Linux community (in particular including this
6571 policy, the Linux kernel source, many Debian scripts,
6572 etc.). This <tt>echo -n</tt> mechanism is valid but not
6573 required under POSIX, hence this explicit addition.
6574 Also, rumour has it that this shall be mandated under
6577 Thus, shell scripts specifying <file>/bin/sh</file> as
6578 interpreter should only use POSIX features. If a script
6579 requires non-POSIX features from the shell interpreter, the
6580 appropriate shell must be specified in the first line of the
6581 script (e.g., <tt>#!/bin/bash</tt>) and the package must
6582 depend on the package providing the shell (unless the shell
6583 package is marked "Essential", as in the case of
6588 You may wish to restrict your script to POSIX features when
6589 possible so that it may use <file>/bin/sh</file> as its
6590 interpreter. If your script works with <prgn>dash</prgn>
6591 (originally called <prgn>ash</prgn>), it's probably POSIX
6592 compliant, but if you are in doubt, use
6593 <file>/bin/bash</file>.
6597 Perl scripts should check for errors when making any
6598 system calls, including <tt>open</tt>, <tt>print</tt>,
6599 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
6603 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
6604 scripting languages. See <em>Csh Programming Considered
6605 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
6606 can be found at <url id="http://language.perl.com/versus/csh.whynot">.
6607 If an upstream package comes with <prgn>csh</prgn> scripts
6608 then you must make sure that they start with
6609 <tt>#!/bin/csh</tt> and make your package depend on the
6610 <prgn>c-shell</prgn> virtual package.
6614 Any scripts which create files in world-writeable
6615 directories (e.g., in <file>/tmp</file>) must use a
6616 mechanism which will fail if a file with the same name
6621 The Debian base system provides the <prgn>tempfile</prgn>
6622 and <prgn>mktemp</prgn> utilities for use by scripts for
6629 <heading>Symbolic links</heading>
6632 In general, symbolic links within a top-level directory
6633 should be relative, and symbolic links pointing from one
6634 top-level directory into another should be absolute. (A
6635 top-level directory is a sub-directory of the root
6636 directory <file>/</file>.)
6640 In addition, symbolic links should be specified as short as
6641 possible, i.e., link targets like <file>foo/../bar</file> are
6646 Note that when creating a relative link using
6647 <prgn>ln</prgn> it is not necessary for the target of the
6648 link to exist relative to the working directory you're
6649 running <prgn>ln</prgn> from, nor is it necessary to change
6650 directory to the directory where the link is to be made.
6651 Simply include the string that should appear as the target
6652 of the link (this will be a pathname relative to the
6653 directory in which the link resides) as the first argument
6658 For example, in your <prgn>Makefile</prgn> or
6659 <file>debian/rules</file>, you can do things like:
6660 <example compact="compact">
6661 ln -fs gcc $(prefix)/bin/cc
6662 ln -fs gcc debian/tmp/usr/bin/cc
6663 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6664 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6669 A symbolic link pointing to a compressed file should always
6670 have the same file extension as the referenced file. (For
6671 example, if a file <file>foo.gz</file> is referenced by a
6672 symbolic link, the filename of the link has to end with
6673 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6678 <heading>Device files</heading>
6681 Packages must not include device files in the package file
6686 If a package needs any special device files that are not
6687 included in the base system, it must call
6688 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6689 after notifying the user<footnote>
6690 This notification could be done via a (low-priority)
6691 debconf message, or an echo (printf) statement.
6696 Packages must not remove any device files in the
6697 <prgn>postrm</prgn> or any other script. This is left to the
6698 system administrator.
6702 Debian uses the serial devices
6703 <file>/dev/ttyS*</file>. Programs using the old
6704 <file>/dev/cu*</file> devices should be changed to use
6705 <file>/dev/ttyS*</file>.
6709 <sect id="config-files">
6710 <heading>Configuration files</heading>
6713 <heading>Definitions</heading>
6717 <tag>configuration file</tag>
6719 A file that affects the operation of a program, or
6720 provides site- or host-specific information, or
6721 otherwise customizes the behavior of a program.
6722 Typically, configuration files are intended to be
6723 modified by the system administrator (if needed or
6724 desired) to conform to local policy or to provide
6725 more useful site-specific behavior.
6728 <tag><tt>conffile</tt></tag>
6730 A file listed in a package's <tt>conffiles</tt>
6731 file, and is treated specially by <prgn>dpkg</prgn>
6732 (see <ref id="configdetails">).
6738 The distinction between these two is important; they are
6739 not interchangeable concepts. Almost all
6740 <tt>conffile</tt>s are configuration files, but many
6741 configuration files are not <tt>conffiles</tt>.
6745 Note that a script that embeds configuration information
6746 (such as most of the files in <file>/etc/default</file> and
6747 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6748 configuration file and should be treated as such.
6753 <heading>Location</heading>
6756 Any configuration files created or used by your package
6757 must reside in <file>/etc</file>. If there are several,
6758 consider creating a subdirectory of <file>/etc</file>
6759 named after your package.
6763 If your package creates or uses configuration files
6764 outside of <file>/etc</file>, and it is not feasible to modify
6765 the package to use <file>/etc</file> directly, put the files
6766 in <file>/etc</file> and create symbolic links to those files
6767 from the location that the package requires.
6772 <heading>Behavior</heading>
6775 Configuration file handling must conform to the following
6777 <list compact="compact">
6779 local changes must be preserved during a package
6783 configuration files must be preserved when the
6784 package is removed, and only deleted when the
6791 The easy way to achieve this behavior is to make the
6792 configuration file a <tt>conffile</tt>. This is
6793 appropriate only if it is possible to distribute a default
6794 version that will work for most installations, although
6795 some system administrators may choose to modify it. This
6796 implies that the default version will be part of the
6797 package distribution, and must not be modified by the
6798 maintainer scripts during installation (or at any other
6803 In order to ensure that local changes are preserved
6804 correctly, no package may contain or make hard links to
6805 conffiles.<footnote>
6806 Rationale: There are two problems with hard links.
6807 The first is that some editors break the link while
6808 editing one of the files, so that the two files may
6809 unwittingly become unlinked and different. The second
6810 is that <prgn>dpkg</prgn> might break the hard link
6811 while upgrading <tt>conffile</tt>s.
6816 The other way to do it is via the maintainer scripts. In
6817 this case, the configuration file must not be listed as a
6818 <tt>conffile</tt> and must not be part of the package
6819 distribution. If the existence of a file is required for
6820 the package to be sensibly configured it is the
6821 responsibility of the package maintainer to provide
6822 maintainer scripts which correctly create, update and
6823 maintain the file and remove it on purge. (See <ref
6824 id="maintainerscripts"> for more information.) These
6825 scripts must be idempotent (i.e., must work correctly if
6826 <prgn>dpkg</prgn> needs to re-run them due to errors
6827 during installation or removal), must cope with all the
6828 variety of ways <prgn>dpkg</prgn> can call maintainer
6829 scripts, must not overwrite or otherwise mangle the user's
6830 configuration without asking, must not ask unnecessary
6831 questions (particularly during upgrades), and otherwise be
6836 The scripts are not required to configure every possible
6837 option for the package, but only those necessary to get
6838 the package running on a given system. Ideally the
6839 sysadmin should not have to do any configuration other
6840 than that done (semi-)automatically by the
6841 <prgn>postinst</prgn> script.
6845 A common practice is to create a script called
6846 <file><var>package</var>-configure</file> and have the
6847 package's <prgn>postinst</prgn> call it if and only if the
6848 configuration file does not already exist. In certain
6849 cases it is useful for there to be an example or template
6850 file which the maintainer scripts use. Such files should
6851 be in <file>/usr/share/<var>package</var></file> or
6852 <file>/usr/lib/<var>package</var></file> (depending on whether
6853 they are architecture-independent or not). There should
6854 be symbolic links to them from
6855 <file>/usr/share/doc/<var>package</var>/examples</file> if
6856 they are examples, and should be perfectly ordinary
6857 <prgn>dpkg</prgn>-handled files (<em>not</em>
6858 configuration files).
6862 These two styles of configuration file handling must
6863 not be mixed, for that way lies madness:
6864 <prgn>dpkg</prgn> will ask about overwriting the file
6865 every time the package is upgraded.
6870 <heading>Sharing configuration files</heading>
6873 Packages which specify the same file as a
6874 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6875 with each other. (This is an instance of the general rule
6876 about not sharing files. Note that neither alternatives
6877 nor diversions are likely to be appropriate in this case;
6878 in particular, <prgn>dpkg</prgn> does not handle diverted
6879 <tt>conffile</tt>s well.)
6883 The maintainer scripts must not alter a <tt>conffile</tt>
6884 of <em>any</em> package, including the one the scripts
6889 If two or more packages use the same configuration file
6890 and it is reasonable for both to be installed at the same
6891 time, one of these packages must be defined as
6892 <em>owner</em> of the configuration file, i.e., it will be
6893 the package which handles that file as a configuration
6894 file. Other packages that use the configuration file must
6895 depend on the owning package if they require the
6896 configuration file to operate. If the other package will
6897 use the configuration file if present, but is capable of
6898 operating without it, no dependency need be declared.
6902 If it is desirable for two or more related packages to
6903 share a configuration file <em>and</em> for all of the
6904 related packages to be able to modify that configuration
6905 file, then the following should be done:
6906 <enumlist compact="compact">
6908 One of the related packages (the "owning" package)
6909 will manage the configuration file with maintainer
6910 scripts as described in the previous section.
6913 The owning package should also provide a program
6914 that the other packages may use to modify the
6918 The related packages must use the provided program
6919 to make any desired modifications to the
6920 configuration file. They should either depend on
6921 the core package to guarantee that the configuration
6922 modifier program is available or accept gracefully
6923 that they cannot modify the configuration file if it
6924 is not. (This is in addition to the fact that the
6925 configuration file may not even be present in the
6932 Sometimes it's appropriate to create a new package which
6933 provides the basic infrastructure for the other packages
6934 and which manages the shared configuration files. (The
6935 <tt>sgml-base</tt> package is a good example.)
6940 <heading>User configuration files ("dotfiles")</heading>
6943 The files in <file>/etc/skel</file> will automatically be
6944 copied into new user accounts by <prgn>adduser</prgn>.
6945 No other program should reference the files in
6946 <file>/etc/skel</file>.
6950 Therefore, if a program needs a dotfile to exist in
6951 advance in <file>$HOME</file> to work sensibly, that dotfile
6952 should be installed in <file>/etc/skel</file> and treated as a
6957 However, programs that require dotfiles in order to
6958 operate sensibly are a bad thing, unless they do create
6959 the dotfiles themselves automatically.
6963 Furthermore, programs should be configured by the Debian
6964 default installation to behave as closely to the upstream
6965 default behaviour as possible.
6969 Therefore, if a program in a Debian package needs to be
6970 configured in some way in order to operate sensibly, that
6971 should be done using a site-wide configuration file placed
6972 in <file>/etc</file>. Only if the program doesn't support a
6973 site-wide default configuration and the package maintainer
6974 doesn't have time to add it may a default per-user file be
6975 placed in <file>/etc/skel</file>.
6979 <file>/etc/skel</file> should be as empty as we can make it.
6980 This is particularly true because there is no easy (or
6981 necessarily desirable) mechanism for ensuring that the
6982 appropriate dotfiles are copied into the accounts of
6983 existing users when a package is installed.
6989 <heading>Log files</heading>
6991 Log files should usually be named
6992 <file>/var/log/<var>package</var>.log</file>. If you have many
6993 log files, or need a separate directory for permission
6994 reasons (<file>/var/log</file> is writable only by
6995 <file>root</file>), you should usually create a directory named
6996 <file>/var/log/<var>package</var></file> and place your log
7001 Log files must be rotated occasionally so that they don't
7002 grow indefinitely; the best way to do this is to drop a log
7003 rotation configuration file into the directory
7004 <file>/etc/logrotate.d</file> and use the facilities provided by
7005 logrotate.<footnote>
7007 The traditional approach to log files has been to set up
7008 <em>ad hoc</em> log rotation schemes using simple shell
7009 scripts and cron. While this approach is highly
7010 customizable, it requires quite a lot of sysadmin work.
7011 Even though the original Debian system helped a little
7012 by automatically installing a system which can be used
7013 as a template, this was deemed not enough.
7017 The use of <prgn>logrotate</prgn>, a program developed
7018 by Red Hat, is better, as it centralizes log management.
7019 It has both a configuration file
7020 (<file>/etc/logrotate.conf</file>) and a directory where
7021 packages can drop their individual log rotation
7022 configurations (<file>/etc/logrotate.d</file>).
7025 Here is a good example for a logrotate config
7026 file (for more information see <manref name="logrotate"
7028 <example compact="compact">
7029 /var/log/foo/*.log {
7034 /etc/init.d/foo force-reload
7038 This rotates all files under <file>/var/log/foo</file>, saves 12
7039 compressed generations, and forces the daemon to reload its
7040 configuration information after the log rotation.
7044 Log files should be removed when the package is
7045 purged (but not when it is only removed). This should be
7046 done by the <prgn>postrm</prgn> script when it is called
7047 with the argument <tt>purge</tt> (see <ref
7048 id="removedetails">).
7053 <heading>Permissions and owners</heading>
7056 The rules in this section are guidelines for general use.
7057 If necessary you may deviate from the details below.
7058 However, if you do so you must make sure that what is done
7059 is secure and you should try to be as consistent as possible
7060 with the rest of the system. You should probably also
7061 discuss it on <prgn>debian-devel</prgn> first.
7065 Files should be owned by <tt>root.root</tt>, and made
7066 writable only by the owner and universally readable (and
7067 executable, if appropriate), that is mode 644 or 755.
7071 Directories should be mode 755 or (for group-writability)
7072 mode 2775. The ownership of the directory should be
7073 consistent with its mode: if a directory is mode 2775, it
7074 should be owned by the group that needs write access to
7079 Setuid and setgid executables should be mode 4755 or 2755
7080 respectively, and owned by the appropriate user or group.
7081 They should not be made unreadable (modes like 4711 or
7082 2711 or even 4111); doing so achieves no extra security,
7083 because anyone can find the binary in the freely available
7084 Debian package; it is merely inconvenient. For the same
7085 reason you should not restrict read or execute permissions
7086 on non-set-id executables.
7090 Some setuid programs need to be restricted to particular
7091 sets of users, using file permissions. In this case they
7092 should be owned by the uid to which they are set-id, and by
7093 the group which should be allowed to execute them. They
7094 should have mode 4754; again there is no point in making
7095 them unreadable to those users who must not be allowed to
7100 It is possible to arrange that the system administrator can
7101 reconfigure the package to correspond to their local
7102 security policy by changing the permissions on a binary:
7103 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7104 described below.<footnote>
7105 Ordinary files installed by <prgn>dpkg</prgn> (as
7106 opposed to <tt>conffile</tt>s and other similar objects)
7107 normally have their permissions reset to the distributed
7108 permissions when the package is reinstalled. However,
7109 the use of <prgn>dpkg-statoverride</prgn> overrides this
7110 default behaviour. If you use this method, you should
7111 remember to describe <prgn>dpkg-statoverride</prgn> in
7112 the package documentation; being a relatively new
7113 addition to Debian, it is probably not yet well-known.
7115 Another method you should consider is to create a group for
7116 people allowed to use the program(s) and make any setuid
7117 executables executable only by that group.
7121 If you need to create a new user or group for your package
7122 there are two possibilities. Firstly, you may need to
7123 make some files in the binary package be owned by this
7124 user or group, or you may need to compile the user or
7125 group id (rather than just the name) into the binary
7126 (though this latter should be avoided if possible, as in
7127 this case you need a statically allocated id).</p>
7130 If you need a statically allocated id, you must ask for a
7131 user or group id from the <tt>base-passwd</tt> maintainer,
7132 and must not release the package until you have been
7133 allocated one. Once you have been allocated one you must
7134 either make the package depend on a version of the
7135 <tt>base-passwd</tt> package with the id present in
7136 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7137 your package to create the user or group itself with the
7138 correct id (using <tt>adduser</tt>) in its
7139 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7140 the <prgn>postinst</prgn> is to be preferred if it is
7141 possible, otherwise a pre-dependency will be needed on the
7142 <tt>adduser</tt> package.)
7146 On the other hand, the program might be able to determine
7147 the uid or gid from the user or group name at runtime, so
7148 that a dynamically allocated id can be used. In this case
7149 you should choose an appropriate user or group name,
7150 discussing this on <prgn>debian-devel</prgn> and checking
7151 with the <package/base-passwd/ maintainer that it is unique and that
7152 they do not wish you to use a statically allocated id
7153 instead. When this has been checked you must arrange for
7154 your package to create the user or group if necessary using
7155 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7156 <prgn>postinst</prgn> script (again, the latter is to be
7157 preferred if it is possible).
7161 Note that changing the numeric value of an id associated
7162 with a name is very difficult, and involves searching the
7163 file system for all appropriate files. You need to think
7164 carefully whether a static or dynamic id is required, since
7165 changing your mind later will cause problems.
7168 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7170 This section is not intended as policy, but as a
7171 description of the use of <prgn>dpkg-statoverride</prgn>.
7175 <prgn>dpkg-statoverride</prgn> is a replacement for the
7176 deprecated <tt>suidmanager</tt> package. Packages which
7177 previously used <tt>suidmanager</tt> should have a
7178 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
7179 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
7180 and <tt>suidunregister</tt> should now be simply removed
7181 from the maintainer scripts.
7185 If a system administrator wishes to have a file (or
7186 directory or other such thing) installed with owner and
7187 permissions different from those in the distributed Debian
7188 package, he can use the <prgn>dpkg-statoverride</prgn>
7189 program to instruct <prgn>dpkg</prgn> to use the different
7190 settings every time the file is installed. Thus the
7191 package maintainer should distribute the files with their
7192 normal permissions, and leave it for the system
7193 administrator to make any desired changes. For example, a
7194 daemon which is normally required to be setuid root, but
7195 in certain situations could be used without being setuid,
7196 should be installed setuid in the <tt>.deb</tt>. Then the
7197 local system administrator can change this if they wish.
7198 If there are two standard ways of doing it, the package
7199 maintainer can use <tt>debconf</tt> to find out the
7200 preference, and call <prgn>dpkg-statoverride</prgn> in the
7201 maintainer script if necessary to accommodate the system
7202 administrator's choice.
7206 Given the above, <prgn>dpkg-statoverride</prgn> is
7207 essentially a tool for system administrators and would not
7208 normally be needed in the maintainer scripts. There is
7209 one type of situation, though, where calls to
7210 <prgn>dpkg-statoverride</prgn> would be needed in the
7211 maintainer scripts, and that involves packages which use
7212 dynamically allocated user or group ids. In such a
7213 situation, something like the following idiom can be very
7214 helpful in the package's <prgn>postinst</prgn>, where
7215 <tt>sysuser</tt> is a dynamically allocated id:
7217 for i in /usr/bin/foo /usr/sbin/bar
7219 if ! dpkg-statoverride --list $i >/dev/null
7221 dpkg-statoverride --update --add sysuser root 4755 $i
7225 The corresponding <tt>dpkg-statoverride --remove</tt>
7226 calls can then be made unconditionally when the package is
7234 <chapt id="customized-programs">
7235 <heading>Customized programs</heading>
7237 <sect id="arch-spec">
7238 <heading>Architecture specification strings</heading>
7241 If a program needs to specify an <em>architecture specification
7242 string</em> in some place, the following format should be
7243 used: <var>arch</var>-<var>os</var><footnote>
7244 The following architectures and operating systems are
7245 currently recognised by <prgn>dpkg-archictecture</prgn>.
7246 The architecture, <tt><var>arch</var></tt>, is one of
7247 the following: <tt>alpha</tt>, <tt>arm</tt>,
7248 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
7249 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
7250 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
7251 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
7252 operating system, <tt><var>os</var></tt>, is one of:
7253 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
7254 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
7255 reserved for the GNU/Hurd operating system.
7260 Note that we don't want to use
7261 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7262 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7263 since this would make our programs incompatible with other
7264 Linux distributions. We also don't use something like
7265 <tt><var>arch</var>-unknown-linux</tt>, since the
7266 <tt>unknown</tt> does not look very good.
7271 <heading>Daemons</heading>
7274 The configuration files <file>/etc/services</file>,
7275 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7276 by the <prgn>netbase</prgn> package and must not be modified
7281 If a package requires a new entry in one of these files, the
7282 maintainer should get in contact with the
7283 <prgn>netbase</prgn> maintainer, who will add the entries
7284 and release a new version of the <prgn>netbase</prgn>
7289 The configuration file <file>/etc/inetd.conf</file> must not be
7290 modified by the package's scripts except via the
7291 <prgn>update-inetd</prgn> script or the
7292 <file>DebianNet.pm</file> Perl module. See their documentation
7293 for details on how to add entries.
7297 If a package wants to install an example entry into
7298 <file>/etc/inetd.conf</file>, the entry must be preceded with
7299 exactly one hash character (<tt>#</tt>). Such lines are
7300 treated as "commented out by user" by the
7301 <prgn>update-inetd</prgn> script and are not changed or
7302 activated during package updates.
7307 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7311 Some programs need to create pseudo-ttys. This should be done
7312 using Unix98 ptys if the C library supports it. The resulting
7313 program must not be installed setuid root, unless that
7314 is required for other functionality.
7318 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7319 <file>/var/log/lastlog</file> must be installed writeable by
7320 group <tt>utmp</tt>. Programs which need to modify those
7321 files must be installed setgid <tt>utmp</tt>.
7326 <heading>Editors and pagers</heading>
7329 Some programs have the ability to launch an editor or pager
7330 program to edit or display a text document. Since there are
7331 lots of different editors and pagers available in the Debian
7332 distribution, the system administrator and each user should
7333 have the possibility to choose his/her preferred editor and
7338 In addition, every program should choose a good default
7339 editor/pager if none is selected by the user or system
7344 Thus, every program that launches an editor or pager must
7345 use the EDITOR or PAGER environment variable to determine
7346 the editor or pager the user wishes to use. If these
7347 variables are not set, the programs <file>/usr/bin/editor</file>
7348 and <file>/usr/bin/pager</file> should be used, respectively.
7352 These two files are managed through the <prgn>dpkg</prgn>
7353 "alternatives" mechanism. Thus every package providing an
7354 editor or pager must call the
7355 <prgn>update-alternatives</prgn> script to register these
7360 If it is very hard to adapt a program to make use of the
7361 EDITOR or PAGER variables, that program may be configured to
7362 use <file>/usr/bin/sensible-editor</file> and
7363 <file>/usr/bin/sensible-pager</file> as the editor or pager
7364 program respectively. These are two scripts provided in the
7365 Debian base system that check the EDITOR and PAGER variables
7366 and launch the appropriate program, and fall back to
7367 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7368 variable is not set.
7372 A program may also use the VISUAL environment variable to
7373 determine the user's choice of editor. If it exists, it
7374 should take precedence over EDITOR. This is in fact what
7375 <file>/usr/bin/sensible-editor</file> does.
7379 It is not required for a package to depend on
7380 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7381 package to provide such virtual packages.<footnote>
7382 The Debian base system already provides an editor and a
7388 <sect id="web-appl">
7389 <heading>Web servers and applications</heading>
7392 This section describes the locations and URLs that should
7393 be used by all web servers and web applications in the
7400 Cgi-bin executable files are installed in the
7402 <example compact="compact">
7403 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7405 and should be referred to as
7406 <example compact="compact">
7407 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7412 <p>Access to HTML documents</p>
7415 HTML documents for a package are stored in
7416 <file>/usr/share/doc/<var>package</var></file>
7417 and can be referred to as
7418 <example compact="compact">
7419 http://localhost/doc/<var>package</var>/<var>filename</var>
7424 The web server should restrict access to the document
7425 tree so that only clients on the same host can read
7426 the documents. If the web server does not support such
7427 access controls, then it should not provide access at
7428 all, or ask about providing access during installation.
7433 <p>Web Document Root</p>
7436 Web Applications should try to avoid storing files in
7437 the Web Document Root. Instead they should use the
7438 /usr/share/doc/<var>package</var> directory for
7439 documents and register the Web Application via the
7440 menu package. If access to the web document root is
7441 unavoidable then use
7442 <example compact="compact">
7445 as the Document Root. This might be just a symbolic
7446 link to the location where the system administrator
7447 has put the real document root.
7455 <sect id="mail-transport-agents">
7456 <heading>Mail transport, delivery and user agents</heading>
7459 Debian packages which process electronic mail, whether mail
7460 user agents (MUAs) or mail transport agents (MTAs), must
7461 ensure that they are compatible with the configuration
7462 decisions below. Failure to do this may result in lost
7463 mail, broken <tt>From:</tt> lines, and other serious brain
7468 The mail spool is <file>/var/mail</file> and the interface to
7469 send a mail message is <file>/usr/sbin/sendmail</file> (as per
7470 the FHS). On older systems, the mail spool may be
7471 physically located in <file>/var/spool/mail</file>, but all
7472 access to the mail spool should be via the
7473 <file>/var/mail</file> symlink. The mail spool is part of the
7474 base system and not part of the MTA package.
7478 All Debian MUAs, MTAs, MDAs and other mailbox accessing
7479 programs (such as IMAP daemons) must lock the mailbox in an
7480 NFS-safe way. This means that <tt>fcntl()</tt> locking must
7481 be combined with dot locking. To avoid deadlocks, a program
7482 should use <tt>fcntl()</tt> first and dot locking after
7483 this, or alternatively implement the two locking methods in
7484 a non blocking way<footnote>
7485 If it is not possible to establish both locks, the
7486 system shouldn't wait for the second lock to be
7487 established, but remove the first lock, wait a (random)
7488 time, and start over locking again.
7489 </footnote>. Using the functions <tt>maillock</tt> and
7490 <tt>mailunlock</tt> provided by the
7491 <tt>liblockfile*</tt><footnote>
7492 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
7493 to use these functions.
7494 </footnote> packages is the recommended way to realize this.
7498 Mailboxes are generally mode 660
7499 <tt><var>user</var>.mail</tt> unless the system
7500 administrator has chosen otherwise. A MUA may remove a
7501 mailbox (unless it has nonstandard permissions) in which
7502 case the MTA or another MUA must recreate it if needed.
7503 Mailboxes must be writable by group mail.
7507 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
7508 be setgid mail to do the locking mentioned above (and
7509 must obviously avoid accessing other users' mailboxes
7510 using this privilege).</p>
7513 <file>/etc/aliases</file> is the source file for the system mail
7514 aliases (e.g., postmaster, usenet, etc.), it is the one
7515 which the sysadmin and <prgn>postinst</prgn> scripts may
7516 edit. After <file>/etc/aliases</file> is edited the program or
7517 human editing it must call <prgn>newaliases</prgn>. All MTA
7518 packages must come with a <prgn>newaliases</prgn> program,
7519 even if it does nothing, but older MTA packages did not do
7520 this so programs should not fail if <prgn>newaliases</prgn>
7521 cannot be found. Note that because of this, all MTA
7522 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
7523 <tt>Replaces: mail-transport-agent</tt> control file
7528 The convention of writing <tt>forward to
7529 <var>address</var></tt> in the mailbox itself is not
7530 supported. Use a <tt>.forward</tt> file instead.</p>
7533 The <prgn>rmail</prgn> program used by UUCP
7534 for incoming mail should be <file>/usr/sbin/rmail</file>.
7535 Likewise, <prgn>rsmtp</prgn>, for receiving
7536 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
7540 If your package needs to know what hostname to use on (for
7541 example) outgoing news and mail messages which are generated
7542 locally, you should use the file <file>/etc/mailname</file>. It
7543 will contain the portion after the username and <tt>@</tt>
7544 (at) sign for email addresses of users on the machine
7545 (followed by a newline).
7549 Such package should check for the existence of this file
7550 when it is being configured. If it exists, it should be
7551 used without comment, although an MTA's configuration script
7552 may wish to prompt the user even if it finds that this file
7553 exists. If the file does not exist, the package should
7554 prompt the user for the value (preferably using
7555 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
7556 as well as using it in the package's configuration. The
7557 prompt should make it clear that the name will not just be
7558 used by that package. For example, in this situation the
7559 <tt>inn</tt> package could say something like:
7560 <example compact="compact">
7561 Please enter the "mail name" of your system. This is the
7562 hostname portion of the address to be shown on outgoing
7563 news and mail messages. The default is
7564 <var>syshostname</var>, your system's host name. Mail
7565 name ["<var>syshostname</var>"]:
7567 where <var>syshostname</var> is the output of <tt>hostname
7573 <heading>News system configuration</heading>
7576 All the configuration files related to the NNTP (news)
7577 servers and clients should be located under
7578 <file>/etc/news</file>.</p>
7581 There are some configuration issues that apply to a number
7582 of news clients and server packages on the machine. These
7586 <tag><file>/etc/news/organization</file></tag>
7588 A string which should appear as the
7589 organization header for all messages posted
7590 by NNTP clients on the machine
7593 <tag><file>/etc/news/server</file></tag>
7595 Contains the FQDN of the upstream NNTP
7596 server, or localhost if the local machine is
7601 Other global files may be added as required for cross-package news
7608 <heading>Programs for the X Window System</heading>
7611 <heading>Providing X support and package priorities</heading>
7614 Programs that can be configured with support for the X
7615 Window System must be configured to do so and must declare
7616 any package dependencies necessary to satisfy their
7617 runtime requirements when using the X Window System. If
7618 such a package is of higher priority than the X packages
7619 on which it depends, it is required that either the
7620 X-specific components be split into a separate package, or
7621 that an alternative version of the package, which includes
7622 X support, be provided, or that the package's priority be
7628 <heading>Packages providing an X server</heading>
7631 Packages that provide an X server that, directly or
7632 indirectly, communicates with real input and display
7633 hardware should declare in their control data that they
7634 provide the virtual package <tt>xserver</tt>.<footnote>
7635 This implements current practice, and provides an
7636 actual policy for usage of the <tt>xserver</tt>
7637 virtual package which appears in the virtual packages
7638 list. In a nutshell, X servers that interface
7639 directly with the display and input hardware or via
7640 another subsystem (e.g., GGI) should provide
7641 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7642 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7648 <heading>Packages providing a terminal emulator</heading>
7651 Packages that provide a terminal emulator for the X Window
7652 System which meet the criteria listed below should declare
7653 in their control data that they provide the virtual
7654 package <tt>x-terminal-emulator</tt>. They should also
7655 register themselves as an alternative for
7656 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7661 To be an <tt>x-terminal-emulator</tt>, a program must:
7662 <list compact="compact">
7664 Be able to emulate a DEC VT100 terminal, or a
7665 compatible terminal.
7669 Support the command-line option <tt>-e
7670 <var>command</var></tt>, which creates a new
7671 terminal window<footnote>
7672 "New terminal window" does not necessarily mean
7673 a new top-level X window directly parented by
7674 the window manager; it could, if the terminal
7675 emulator application were so coded, be a new
7676 "view" in a multiple-document interface (MDI).
7678 and runs the specified <var>command</var>,
7679 interpreting the entirity of the rest of the command
7680 line as a command to pass straight to exec, in the
7681 manner that <tt>xterm</tt> does.
7685 Support the command-line option <tt>-T
7686 <var>title</var></tt>, which creates a new terminal
7687 window with the window title <var>title</var>.
7694 <heading>Packages providing a window manager</heading>
7697 Packages that provide a window manager should declare in
7698 their control data that they provide the virtual package
7699 <tt>x-window-manager</tt>. They should also register
7700 themselves as an alternative for
7701 <file>/usr/bin/x-window-manager</file>, with a priority
7702 calculated as follows:
7703 <list compact="compact">
7705 Start with a priority of 20.
7709 If the window manager supports the Debian menu
7710 system, add 20 points if this support is available
7711 in the package's default configuration (i.e., no
7712 configuration files belonging to the system or user
7713 have to be edited to activate the feature); if
7714 configuration files must be modified, add only 10
7720 If the window manager complies with <url
7721 id="http://www.freedesktop.org/standards/wm-spec.html"
7722 name="The Window Manager Specification Project">,
7723 written by the <url id="http://www.freedesktop.org/"
7724 name="Free Desktop Group">, add 40 points.
7728 If the window manager permits the X session to be
7729 restarted using a <em>different</em> window manager
7730 (without killing the X server) in its default
7731 configuration, add 10 points; otherwise add none.
7738 <heading>Packages providing fonts</heading>
7741 Packages that provide fonts for the X Window
7743 For the purposes of Debian Policy, a "font for the X
7744 Window System" is one which is accessed via X protocol
7745 requests. Fonts for the Linux console, for PostScript
7746 renderers, or any other purpose, do not fit this
7747 definition. Any tool which makes such fonts available
7748 to the X Window System, however, must abide by this
7751 must do a number of things to ensure that they are both
7752 available without modification of the X or font server
7753 configuration, and that they do not corrupt files used by
7754 other font packages to register information about
7758 Fonts of any type supported by the X Window System
7759 must be in a separate binary package from any
7760 executables, libraries, or documentation (except
7761 that specific to the fonts shipped, such as their
7762 license information). If one or more of the fonts
7763 so packaged are necessary for proper operation of
7764 the package with which they are associated the font
7765 package may be Recommended; if the fonts merely
7766 provide an enhancement, a Suggests relationship may
7767 be used. Packages must not Depend on font
7769 This is because the X server may retrieve fonts
7770 from the local filesystem or over the network
7771 from an X font server; the Debian package system
7772 is empowered to deal only with the local
7778 BDF fonts must be converted to PCF fonts with the
7779 <prgn>bdftopcf</prgn> utility (available in the
7780 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7781 placed in a directory that corresponds to their
7783 <list compact="compact">
7785 100 dpi fonts must be placed in
7786 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7790 75 dpi fonts must be placed in
7791 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7795 Character-cell fonts, cursor fonts, and other
7796 low-resolution fonts must be placed in
7797 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7803 Speedo fonts must be placed in
7804 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7808 Type 1 fonts must be placed in
7809 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7810 metric files are available, they must be placed here
7815 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7816 other than those listed above must be neither
7817 created nor used. (The <file>PEX</file>, <file>CID</file>,
7818 and <file>cyrillic</file> directories are excepted for
7819 historical reasons, but installation of files into
7820 these directories remains discouraged.)
7824 Font packages may, instead of placing files directly
7825 in the X font directories listed above, provide
7826 symbolic links in that font directory pointing to
7827 the files' actual location in the filesystem. Such
7828 a location must comply with the FHS.
7832 Font packages should not contain both 75dpi and
7833 100dpi versions of a font. If both are available,
7834 they should be provided in separate binary packages
7835 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7836 the names of the packages containing the
7837 corresponding fonts.
7841 Fonts destined for the <file>misc</file> subdirectory
7842 should not be included in the same package as 75dpi
7843 or 100dpi fonts; instead, they should be provided in
7844 a separate package with <tt>-misc</tt> appended to
7849 Font packages must not provide the files
7850 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7851 <file>fonts.scale</file> in a font directory:
7854 <file>fonts.dir</file> files must not be provided at all.
7858 <file>fonts.alias</file> and <file>fonts.scale</file>
7859 files, if needed, should be provided in the
7861 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7862 where <var>fontdir</var> is the name of the
7864 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7865 package's corresponding fonts are stored
7866 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7867 <var>package</var> is the name of the package
7868 that provides these fonts, and
7869 <var>extension</var> is either <tt>scale</tt>
7870 or <tt>alias</tt>, whichever corresponds to
7877 Font packages must declare a dependency on
7878 <tt>xutils (>> 4.0.3)</tt> in their control
7883 Font packages that provide one or more
7884 <file>fonts.scale</file> files as described above must
7885 invoke <prgn>update-fonts-scale</prgn> on each
7886 directory into which they installed fonts
7887 <em>before</em> invoking
7888 <prgn>update-fonts-dir</prgn> on that directory.
7889 This invocation must occur in both the
7890 <prgn>postinst</prgn> (for all arguments) and
7891 <prgn>postrm</prgn> (for all arguments except
7892 <tt>upgrade</tt>) scripts.
7896 Font packages that provide one or more
7897 <file>fonts.alias</file> files as described above must
7898 invoke <prgn>update-fonts-alias</prgn> on each
7899 directory into which they installed fonts. This
7900 invocation must occur in both the
7901 <prgn>postinst</prgn> (for all arguments) and
7902 <prgn>postrm</prgn> (for all arguments except
7903 <tt>upgrade</tt>) scripts.
7907 Font packages must invoke
7908 <prgn>update-fonts-dir</prgn> on each directory into
7909 which they installed fonts. This invocation must
7910 occur in both the <prgn>postinst</prgn> (for all
7911 arguments) and <prgn>postrm</prgn> (for all
7912 arguments except <tt>upgrade</tt>) scripts.
7916 Font packages must not provide alias names for the
7917 fonts they include which collide with alias names
7918 already in use by fonts already packaged.
7922 Font packages must not provide fonts with the same
7923 XLFD registry name as another font already packaged.
7930 <heading>Application defaults files</heading>
7933 Application defaults files must be installed in the
7934 directory <file>/etc/X11/app-defaults/</file> (use of a
7935 localized subdirectory of <file>/etc/X11/</file> as described
7936 in the <em>X Toolkit Intrinsics - C Language
7937 Interface</em> manual is also permitted). They must be
7938 registered as <tt>conffile</tt>s or handled as
7939 configuration files. Packages must not provide the
7940 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7944 Customization of programs' X resources may also be
7945 supported with the provision of a file with the same name
7946 as that of the package placed in the
7947 <file>/etc/X11/Xresources/</file> directory, which must
7948 registered as a <tt>conffile</tt> or handled as a
7949 configuration file.<footnote>
7950 Note that this mechanism is not the same as using
7951 app-defaults; app-defaults are tied to the client
7952 binary on the local filesystem, whereas X resources
7953 are stored in the X server and affect all connecting
7956 <em>Important:</em> packages that install files into the
7957 <file>/etc/X11/Xresources/</file> directory must conflict with
7958 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7959 it is possible for the installing package to destroy a
7960 previously-existing <file>/etc/X11/Xresources</file> file
7961 which had been customized by the system administrator.
7966 <heading>Installation directory issues</heading>
7969 Packages using the X Window System should not be
7970 configured to install files under the <file>/usr/X11R6/</file>
7971 directory unless they use <prgn>imake</prgn>. The
7972 <file>/usr/X11R6/</file> directory hierarchy should be
7973 regarded as deprecated for all packages except the X
7974 Window System itself, and those which use the
7975 <prgn>imake</prgn> program it provides, in which case the
7976 packages may transition out of the <file>/usr/X11R6/</file>
7977 directory at the maintainer's discretion.<footnote>
7978 <prgn>Imake</prgn>-using programs are exempt because,
7979 as long as they are written correctly, the pathnames
7980 they use to locate resources and install themselves
7981 are derived wholly from the X Window System
7982 configuration. Thus, in the event that the X Window
7983 System moves to <file>/usr/X11R7/</file>,
7984 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7985 that is required for these programs is a recompile
7986 against the corresponding X Window System library
7987 development packages.
7992 Programs that use GNU <prgn>autoconf</prgn> and
7993 <prgn>automake</prgn> are usually easily configured at
7994 compile time to use <file>/usr/</file> instead of
7995 <file>/usr/X11R6/</file>, and this should be done whenever
7996 possible. Configuration files for window managers and
7997 display managers should be placed in a subdirectory of
7998 <file>/etc/X11/</file> corresponding to the package name due
7999 to these programs' tight integration with the mechanisms
8000 of the X Window System. Application-level programs should
8001 use the <file>/etc/</file> directory unless otherwise mandated
8006 The installation of files into subdirectories
8007 of <file>/usr/X11R6/include/X11/</file> and
8008 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
8009 package maintainers should determine if subdirectories of
8010 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
8011 instead. (The use of symbolic links from the
8012 <file>X11R6</file> directories to other FHS-compliant
8013 locations is encouraged if the program is not easily
8014 configured to look elsewhere for its files.)
8018 Packages must not provide or install files into the directories
8019 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
8020 <file>/usr/lib/X11/</file>. Files within a package should,
8021 however, make reference to these directories, rather than
8022 their <tt>X11R6</tt>-named counterparts
8023 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
8024 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
8025 referred to have not been moved to other FHS-compliant
8031 <heading>The OSF/Motif and OpenMotif libraries</heading>
8034 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8035 OpenMotif libraries</em><footnote>
8036 OSF/Motif and OpenMotif are collectively referred to as
8037 "Motif" in this policy document.
8039 should be compiled against and tested with LessTif (a free
8040 re-implementation of Motif) instead. If the maintainer
8041 judges that the program or programs do not work
8042 sufficiently well with LessTif to be distributed and
8043 supported, but do so when compiled against Motif, then two
8044 versions of the package should be created; one linked
8045 statically against Motif and with <tt>-smotif</tt>
8046 appended to the package name, and one linked dynamically
8047 against Motif and with <tt>-dmotif</tt> appended to the
8052 Both Motif-linked versions are dependent
8053 upon non-DFSG-compliant software and thus cannot be
8054 uploaded to the <em>main</em> distribution; if the
8055 software is itself DFSG-compliant it may be uploaded to
8056 the <em>contrib</em> distribution. While known existing
8057 versions of Motif permit unlimited redistribution of
8058 binaries linked against the library (whether statically or
8059 dynamically), it is the package maintainer's
8060 responsibility to determine whether this is permitted by
8061 the license of the copy of Motif in his or her possession.
8067 <heading>Perl programs and modules</heading>
8070 Perl programs and modules should follow the current Perl policy.
8074 The Perl policy can be found in the <tt>perl-policy</tt>
8075 files in the <tt>debian-policy</tt> package.
8076 It is also available from the Debian web mirrors at
8077 <tt><url name="/doc/packaging-manuals/perl-policy/"
8078 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
8079 and from the Debian archive mirrors at
8080 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
8081 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
8086 <heading>Emacs lisp programs</heading>
8089 Please refer to the "Debian Emacs Policy" for details of how to
8090 package emacs lisp programs.
8094 The Emacs policy is available in
8095 <file>debian-emacs-policy.gz</file> of the
8096 <package>emacsen-common</package> package.
8097 It is also available from the Debian web mirrors at
8098 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8099 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8104 <heading>Games</heading>
8107 The permissions on <file>/var/games</file> are mode 755, owner
8108 <tt>root</tt> and group <tt>root</tt>.
8112 Each game decides on its own security policy.</p>
8115 Games which require protected, privileged access to
8116 high-score files, savegames, etc., may be made
8117 set-<em>group</em>-id (mode 2755) and owned by
8118 <tt>root.games</tt>, and use files and directories with
8119 appropriate permissions (770 <tt>root.games</tt>, for
8120 example). They must not be made
8121 set-<em>user</em>-id, as this causes security problems. (If
8122 an attacker can subvert any set-user-id game they can
8123 overwrite the executable of any other, causing other players
8124 of these games to run a Trojan horse program. With a
8125 set-group-id game the attacker only gets access to less
8126 important game data, and if they can get at the other
8127 players' accounts at all it will take considerably more
8131 Some packages, for example some fortune cookie programs, are
8132 configured by the upstream authors to install with their
8133 data files or other static information made unreadable so
8134 that they can only be accessed through set-id programs
8135 provided. You should not do this in a Debian package: anyone can
8136 download the <file>.deb</file> file and read the data from it,
8137 so there is no point making the files unreadable. Not
8138 making the files unreadable also means that you don't have
8139 to make so many programs set-id, which reduces the risk of a
8143 As described in the FHS, binaries of games should be
8144 installed in the directory <file>/usr/games</file>. This also
8145 applies to games that use the X Window System. Manual pages
8146 for games (X and non-X games) should be installed in
8147 <file>/usr/share/man/man6</file>.</p>
8153 <heading>Documentation</heading>
8156 <heading>Manual pages</heading>
8159 You should install manual pages in <prgn>nroff</prgn> source
8160 form, in appropriate places under <file>/usr/share/man</file>.
8161 You should only use sections 1 to 9 (see the FHS for more
8162 details). You must not install a preformatted "cat page".
8166 Each program, utility, and function should have an
8167 associated manual page included in the same package. It is
8168 suggested that all configuration files also have a manual
8169 page included as well. Manual pages for protocols and other
8170 auxiliary things are optional.
8174 If no manual page is available, this is considered as a bug
8175 and should be reported to the Debian Bug Tracking System (the
8176 maintainer of the package is allowed to write this bug report
8177 themselves, if they so desire). Do not close the bug report
8178 until a proper manpage is available.<footnote>
8179 It is not very hard to write a man page. See the
8180 <url id="http://www.schweikhardt.net/man_page_howto.html"
8181 name="Man-Page-HOWTO">,
8182 <manref name="man" section="7">, the examples
8183 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8184 the helper programs <prgn>help2man</prgn>, or the
8185 directory <file>/usr/share/doc/man-db/examples</file>.
8190 You may forward a complaint about a missing manpage to the
8191 upstream authors, and mark the bug as forwarded in the
8192 Debian bug tracking system. Even though the GNU Project do
8193 not in general consider the lack of a manpage to be a bug,
8194 we do; if they tell you that they don't consider it a bug
8195 you should leave the bug in our bug tracking system open
8200 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8204 If one manpage needs to be accessible via several names it
8205 is better to use a symbolic link than the <file>.so</file>
8206 feature, but there is no need to fiddle with the relevant
8207 parts of the upstream source to change from <file>.so</file> to
8208 symlinks: don't do it unless it's easy. You should not
8209 create hard links in the manual page directories, nor put
8210 absolute filenames in <file>.so</file> directives. The filename
8211 in a <file>.so</file> in a manpage should be relative to the
8212 base of the manpage tree (usually
8213 <file>/usr/share/man</file>). If you do not create any links
8214 (whether symlinks, hard links, or <tt>.so</tt> directives)
8215 in the filesystem to the alternate names of the manpage,
8216 then you should not rely on <prgn>man</prgn> finding your
8217 manpage under those names based solely on the information in
8218 the manpage's header.<footnote>
8219 Supporting this in <prgn>man</prgn> often requires
8220 unreasonable processing time to find a manual page or to
8221 report that none exists, and moves knowledge into man's
8222 database that would be better left in the filesystem.
8223 This support is therefore deprecated and will cease to
8224 be present in the future.
8230 <heading>Info documents</heading>
8233 Info documents should be installed in <file>/usr/share/info</file>.
8234 They should be compressed with <tt>gzip -9</tt>.
8238 Your package should call <prgn>install-info</prgn> to update
8239 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8240 script when called with a <tt>configure</tt> argument, for
8242 <example compact="compact">
8243 install-info --quiet --section Development Development \
8244 /usr/share/info/foobar.info
8248 It is a good idea to specify a section for the location of
8249 your program; this is done with the <tt>--section</tt>
8250 switch. To determine which section to use, you should look
8251 at <file>/usr/share/info/dir</file> on your system and choose the most
8252 relevant (or create a new section if none of the current
8253 sections are relevant). Note that the <tt>--section</tt>
8254 flag takes two arguments; the first is a regular expression
8255 to match (case-insensitively) against an existing section,
8256 the second is used when creating a new one.</p>
8259 You should remove the entries in the <prgn>prerm</prgn>
8260 script when called with a <tt>remove</tt> argument:
8261 <example compact="compact">
8262 install-info --quiet --remove /usr/share/info/foobar.info
8266 If <prgn>install-info</prgn> cannot find a description entry
8267 in the Info file you must supply one. See <manref
8268 name="install-info" section="8"> for details.</p>
8272 <heading>Additional documentation</heading>
8275 Any additional documentation that comes with the package may
8276 be installed at the discretion of the package maintainer.
8277 Text documentation should be installed in the directory
8278 <file>/usr/share/doc/<var>package</var></file>, where
8279 <var>package</var> is the name of the package, and
8280 compressed with <tt>gzip -9</tt> unless it is small.
8284 If a package comes with large amounts of documentation which
8285 many users of the package will not require you should create
8286 a separate binary package to contain it, so that it does not
8287 take up disk space on the machines of users who do not need
8288 or want it installed.</p>
8291 It is often a good idea to put text information files
8292 (<file>README</file>s, changelogs, and so forth) that come with
8293 the source package in <file>/usr/share/doc/<var>package</var></file>
8294 in the binary package. However, you don't need to install
8295 the instructions for building and installing the package, of
8299 Packages must not require the existence of any files in
8300 <file>/usr/share/doc/</file> in order to function
8302 The system administrator should be able to
8303 delete files in <file>/usr/share/doc/</file> without causing
8304 any programs to break.
8306 Any files that are referenced by programs but are also
8307 useful as standalone documentation should be installed under
8308 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8309 <file>/usr/share/doc/<var>package</var></file>.
8313 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8314 link to another directory in <file>/usr/share/doc</file> only if
8315 the two packages both come from the same source and the
8316 first package Depends on the second.
8320 Former Debian releases placed all additional documentation
8321 in <file>/usr/doc/<var>package</var></file>. This has been
8322 changed to <file>/usr/share/doc/<var>package</var></file>,
8323 and packages must not put documentation in the directory
8324 <file>/usr/doc/<var>package</var></file>. <footnote>
8325 At this phase of the transition, we no longer require a
8326 symbolic link in <file>/usr/doc/</file>. At a later point,
8327 policy shall change to make the symbolic links a bug.
8333 <heading>Preferred documentation formats</heading>
8336 The unification of Debian documentation is being carried out
8340 If your package comes with extensive documentation in a
8341 markup format that can be converted to various other formats
8342 you should if possible ship HTML versions in a binary
8343 package, in the directory
8344 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8345 its subdirectories.<footnote>
8346 The rationale: The important thing here is that HTML
8347 docs should be available in <em>some</em> package, not
8348 necessarily in the main binary package.
8353 Other formats such as PostScript may be provided at the
8354 package maintainer's discretion.
8358 <sect id="copyrightfile">
8359 <heading>Copyright information</heading>
8362 Every package must be accompanied by a verbatim copy of its
8363 copyright and distribution license in the file
8364 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8365 file must neither be compressed nor be a symbolic link.
8369 In addition, the copyright file must say where the upstream
8370 sources (if any) were obtained. It should name the original
8371 authors of the package and the Debian maintainer(s) who were
8372 involved with its creation.</p>
8375 A copy of the file which will be installed in
8376 <file>/usr/share/doc/<var>package</var>/copyright</file> should
8377 be in <file>debian/copyright</file> in the source package.
8381 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8382 link to another directory in <file>/usr/share/doc</file> only if
8383 the two packages both come from the same source and the
8384 first package Depends on the second. These rules are
8385 important because copyrights must be extractable by
8390 Packages distributed under the UCB BSD license, the Artistic
8391 license, the GNU GPL, and the GNU LGPL should refer to the
8392 files <file>/usr/share/common-licenses/BSD</file>,
8393 <file>/usr/share/common-licenses/Artistic</file>,
8394 <file>/usr/share/common-licenses/GPL</file>, and
8395 <file>/usr/share/common-licenses/LGPL</file> respectively,
8396 rather than quoting them in the copyright file.
8400 You should not use the copyright file as a general <file>README</file>
8401 file. If your package has such a file it should be
8402 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
8403 <file>README.Debian</file> or some other appropriate place.</p>
8407 <heading>Examples</heading>
8410 Any examples (configurations, source files, whatever),
8411 should be installed in a directory
8412 <file>/usr/share/doc/<var>package</var>/examples</file>. These
8413 files should not be referenced by any program: they're there
8414 for the benefit of the system administrator and users as
8415 documentation only. Architecture-specific example files
8416 should be installed in a directory
8417 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
8419 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
8420 latter directory itself may be a symbolic link to the
8425 If the purpose of a package is to provide examples, then the
8426 example files may be installed into
8427 <file>/usr/share/doc/<var>package</var></file>.
8431 <sect id="changelogs">
8432 <heading>Changelog files</heading>
8435 Packages that are not Debian-native must contain a
8436 compressed copy of the <file>debian/changelog</file> file from
8437 the Debian source tree in
8438 <file>/usr/share/doc/<var>package</var></file> with the name
8439 <file>changelog.Debian.gz</file>.
8443 If an upstream changelog is available, it should be accessible as
8444 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
8445 plain text. If the upstream changelog is distributed in
8446 HTML, it should be made available in that form as
8447 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
8448 and a plain text <file>changelog.gz</file> should be generated
8449 from it using, for example, <tt>lynx -dump -nolist</tt>. If
8450 the upstream changelog files do not already conform to this
8451 naming convention, then this may be achieved either by
8452 renaming the files, or by adding a symbolic link, at the
8453 maintainer's discretion.<footnote>
8454 Rationale: People should not have to look in places for
8455 upstream changelogs merely because they are given
8456 different names or are distributed in HTML format.
8461 All of these files should be installed compressed using
8462 <tt>gzip -9</tt>, as they will become large with time even
8463 if they start out small.
8467 If the package has only one changelog which is used both as
8468 the Debian changelog and the upstream one because there is
8469 no separate upstream maintainer then that changelog should
8470 usually be installed as
8471 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
8472 there is a separate upstream maintainer, but no upstream
8473 changelog, then the Debian changelog should still be called
8474 <file>changelog.Debian.gz</file>.
8480 <appendix id="pkg-scope">
8481 <heading>Introduction and scope of these appendices</heading>
8484 These appendices are taken essentially verbatim from the
8485 now-deprecated Packaging Manual, version 3.2.1.0. They are
8486 the chapters which are likely to be of use to package
8487 maintainers and which have not already been included in the
8488 policy document itself. Most of these sections are very likely
8489 not relevant to policy; they should be treated as
8490 documentation for the packaging system. Please note that these
8491 appendices are included for convenience, and for historical
8492 reasons: they used to be part of policy package, and they have
8493 not yet been incorporated into dpkg documentation. However,
8494 they still have value, and hence they are presented here.
8498 They have not yet been checked to ensure that they are
8499 compatible with the contents of policy, and if there are any
8500 contradictions, the version in the main policy document takes
8501 precedence. The remaining chapters of the old Packaging
8502 Manual have also not been read in detail to ensure that there
8503 are not parts which have been left out. Both of these will be
8508 Certain parts of the Packaging manual were integrated into the
8509 Policy Manual proper, and removed from the appendices. Links
8510 have been placed from the old locations to the new ones.
8514 <prgn>dpkg</prgn> is a suite of programs for creating binary
8515 package files and installing and removing them on Unix
8517 <prgn>dpkg</prgn> is targetted primarily at Debian
8518 GNU/Linux, but may work on or be ported to other
8524 The binary packages are designed for the management of
8525 installed executable programs (usually compiled binaries) and
8526 their associated data, though source code examples and
8527 documentation are provided as part of some packages.</p>
8530 This manual describes the technical aspects of creating Debian
8531 binary packages (<file>.deb</file> files). It documents the
8532 behaviour of the package management programs
8533 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8534 they interact with packages.</p>
8537 It also documents the interaction between
8538 <prgn>dselect</prgn>'s core and the access method scripts it
8539 uses to actually install the selected packages, and describes
8540 how to create a new access method.</p>
8543 This manual does not go into detail about the options and
8544 usage of the package building and installation tools. It
8545 should therefore be read in conjuction with those programs'
8550 The utility programs which are provided with <prgn>dpkg</prgn>
8551 for managing various system configuration and similar issues,
8552 such as <prgn>update-rc.d</prgn> and
8553 <prgn>install-info</prgn>, are not described in detail here -
8554 please see their manpages.
8558 It is assumed that the reader is reasonably familiar with the
8559 <prgn>dpkg</prgn> System Administrators' manual.
8560 Unfortunately this manual does not yet exist.
8564 The Debian version of the FSF's GNU hello program is provided
8565 as an example for people wishing to create Debian
8566 packages. The Debian <prgn>debmake</prgn> package is
8567 recommended as a very helpful tool in creating and maintaining
8568 Debian packages. However, while the tools and examples are
8569 helpful, they do not replace the need to read and follow the
8570 Policy and Programmer's Manual.</p>
8573 <appendix id="pkg-binarypkg">
8574 <heading>Binary packages (from old Packaging Manual)</heading>
8577 The binary package has two main sections. The first part
8578 consists of various control information files and scripts used
8579 by <prgn>dpkg</prgn> when installing and removing. See <ref
8580 id="pkg-controlarea">.
8584 The second part is an archive containing the files and
8585 directories to be installed.
8589 In the future binary packages may also contain other
8590 components, such as checksums and digital signatures. The
8591 format for the archive is described in full in the
8592 <file>deb(5)</file> manpage.
8596 <sect id="pkg-bincreating"><heading>Creating package files -
8597 <prgn>dpkg-deb</prgn>
8601 All manipulation of binary package files is done by
8602 <prgn>dpkg-deb</prgn>; it's the only program that has
8603 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8604 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8605 will spot that the options requested are appropriate to
8606 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8611 In order to create a binary package you must make a
8612 directory tree which contains all the files and directories
8613 you want to have in the filesystem data part of the package.
8614 In Debian-format source packages this directory is usually
8615 <file>debian/tmp</file>, relative to the top of the package's
8620 They should have the locations (relative to the root of the
8621 directory tree you're constructing) ownerships and
8622 permissions which you want them to have on the system when
8627 With current versions of <prgn>dpkg</prgn> the uid/username
8628 and gid/groupname mappings for the users and groups being
8629 used should be the same on the system where the package is
8630 built and the one where it is installed.
8634 You need to add one special directory to the root of the
8635 miniature filesystem tree you're creating:
8636 <prgn>DEBIAN</prgn>. It should contain the control
8637 information files, notably the binary package control file
8638 (see <ref id="pkg-controlfile">).
8642 The <prgn>DEBIAN</prgn> directory will not appear in the
8643 filesystem archive of the package, and so won't be installed
8644 by <prgn>dpkg</prgn> when the package is installed.
8648 When you've prepared the package, you should invoke:
8650 dpkg --build <var>directory</var>
8655 This will build the package in
8656 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8657 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8658 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8663 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8664 to examine the contents of this newly-created file. You may find the
8665 output of following commands enlightening:
8667 dpkg-deb --info <var>filename</var>.deb
8668 dpkg-deb --contents <var>filename</var>.deb
8669 dpkg --contents <var>filename</var>.deb
8671 To view the copyright file for a package you could use this command:
8673 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8678 <sect id="pkg-controlarea">
8679 <heading>Package control information files</heading>
8682 The control information portion of a binary package is a
8683 collection of files with names known to <prgn>dpkg</prgn>.
8684 It will treat the contents of these files specially - some
8685 of them contain information used by <prgn>dpkg</prgn> when
8686 installing or removing the package; others are scripts which
8687 the package maintainer wants <prgn>dpkg</prgn> to run.
8691 It is possible to put other files in the package control
8692 area, but this is not generally a good idea (though they
8693 will largely be ignored).
8697 Here is a brief list of the control info files supported by
8698 <prgn>dpkg</prgn> and a summary of what they're used for.
8703 <tag><tt>control</tt>
8706 This is the key description file used by
8707 <prgn>dpkg</prgn>. It specifies the package's name
8708 and version, gives its description for the user,
8709 states its relationships with other packages, and so
8710 forth. See <ref id="sourcecontrolfiles"> and
8711 <ref id="binarycontrolfiles">.
8715 It is usually generated automatically from information
8716 in the source package by the
8717 <prgn>dpkg-gencontrol</prgn> program, and with
8718 assistance from <prgn>dpkg-shlibdeps</prgn>.
8719 See <ref id="pkg-sourcetools">.
8723 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8728 These are exectuable files (usually scripts) which
8729 <prgn>dpkg</prgn> runs during installation, upgrade
8730 and removal of packages. They allow the package to
8731 deal with matters which are particular to that package
8732 or require more complicated processing than that
8733 provided by <prgn>dpkg</prgn>. Details of when and
8734 how they are called are in <ref id="maintainerscripts">.
8738 It is very important to make these scripts idempotent.
8739 See <ref id="idempotency">.
8743 The maintainer scripts are guaranteed to run with a
8744 controlling terminal and can interact with the user.
8745 See <ref id="controllingterminal">.
8749 <tag><tt>conffiles</tt>
8752 This file contains a list of configuration files which
8753 are to be handled automatically by <prgn>dpkg</prgn>
8754 (see <ref id="pkg-conffiles">). Note that not necessarily
8755 every configuration file should be listed here.
8758 <tag><tt>shlibs</tt>
8761 This file contains a list of the shared libraries
8762 supplied by the package, with dependency details for
8763 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8764 when it determines what dependencies are required in a
8765 package control file. The <tt>shlibs</tt> file format
8766 is described on <ref id="shlibs">.
8771 <sect id="pkg-controlfile">
8772 <heading>The main control information file: <tt>control</tt></heading>
8775 The most important control information file used by
8776 <prgn>dpkg</prgn> when it installs a package is
8777 <tt>control</tt>. It contains all the package's "vital
8782 The binary package control files of packages built from
8783 Debian sources are made by a special tool,
8784 <prgn>dpkg-gencontrol</prgn>, which reads
8785 <file>debian/control</file> and <file>debian/changelog</file> to
8786 find the information it needs. See <ref id="pkg-sourcepkg"> for
8791 The fields in binary package control files are listed in
8792 <ref id="binarycontrolfiles">.
8796 A description of the syntax of control files and the purpose
8797 of the fields is available in <ref id="controlfields">.
8802 <heading>Time Stamps</heading>
8805 See <ref id="timestamps">.
8810 <appendix id="pkg-sourcepkg">
8811 <heading>Source packages (from old Packaging Manual) </heading>
8814 The Debian binary packages in the distribution are generated
8815 from Debian sources, which are in a special format to assist
8816 the easy and automatic building of binaries.
8819 <sect id="pkg-sourcetools">
8820 <heading>Tools for processing source packages</heading>
8823 Various tools are provided for manipulating source packages;
8824 they pack and unpack sources and help build of binary
8825 packages and help manage the distribution of new versions.
8829 They are introduced and typical uses described here; see
8830 <manref name="dpkg-source" section="1"> for full
8831 documentation about their arguments and operation.
8835 For examples of how to construct a Debian source package,
8836 and how to use those utilities that are used by Debian
8837 source packages, please see the <prgn>hello</prgn> example
8843 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8848 This program is frequently used by hand, and is also
8849 called from package-independent automated building scripts
8850 such as <prgn>dpkg-buildpackage</prgn>.
8854 To unpack a package it is typically invoked with
8856 dpkg-source -x <var>.../path/to/filename</var>.dsc
8861 with the <file><var>filename</var>.tar.gz</file> and
8862 <file><var>filename</var>.diff.gz</file> (if applicable) in
8863 the same directory. It unpacks into
8864 <file><var>package</var>-<var>version</var></file>, and if
8866 <file><var>package</var>-<var>version</var>.orig</file>, in
8867 the current directory.
8871 To create a packed source archive it is typically invoked:
8873 dpkg-source -b <var>package</var>-<var>version</var>
8878 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8879 <file>.diff.gz</file> (if appropriate) in the current
8880 directory. <prgn>dpkg-source</prgn> does not clean the
8881 source tree first - this must be done separately if it is
8886 See also <ref id="pkg-sourcearchives">.</p>
8892 <prgn>dpkg-buildpackage</prgn> - overall package-building
8897 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8898 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8899 targets <tt>clean</tt>, <tt>build</tt> and
8900 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8901 <prgn>pgp</prgn> to build a signed source and binary
8906 It is usually invoked by hand from the top level of the
8907 built or unbuilt source directory. It may be invoked with
8908 no arguments; useful arguments include:
8909 <taglist compact="compact">
8910 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8913 Do not PGP-sign the <tt>.changes</tt> file or the
8914 source package <tt>.dsc</tt> file, respectively.</p>
8916 <tag><tt>-p<var>pgp-command</var></tt></tag>
8919 Invoke <var>pgp-command</var> instead of finding
8920 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8921 <var>pgp-command</var> must behave just like
8922 <prgn>pgp</prgn>.</p>
8924 <tag><tt>-r<var>root-command</var></tt></tag>
8927 When root privilege is required, invoke the command
8928 <var>root-command</var>. <var>root-command</var>
8929 should invoke its first argument as a command, from
8930 the <prgn>PATH</prgn> if necessary, and pass its
8931 second and subsequent arguments to the command it
8932 calls. If no <var>root-command</var> is supplied
8933 then <var>dpkg-buildpackage</var> will take no
8934 special action to gain root privilege, so that for
8935 most packages it will have to be invoked as root to
8938 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8941 Two types of binary-only build and upload - see
8942 <manref name="dpkg-source" section="1">.
8951 <prgn>dpkg-gencontrol</prgn> - generates binary package
8956 This program is usually called from <file>debian/rules</file>
8957 (see <ref id="pkg-sourcetree">) in the top level of the source
8962 This is usually done just before the files and directories in the
8963 temporary directory tree where the package is being built have their
8964 permissions and ownerships set and the package is constructed using
8965 <prgn>dpkg-deb/</prgn>
8967 This is so that the control file which is produced has
8968 the right permissions
8973 <prgn>dpkg-gencontrol</prgn> must be called after all the
8974 files which are to go into the package have been placed in
8975 the temporary build directory, so that its calculation of
8976 the installed size of a package is correct.
8980 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8981 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8982 variable substitutions created by
8983 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8988 For a package which generates only one binary package, and
8989 which builds it in <file>debian/tmp</file> relative to the top
8990 of the source package, it is usually sufficient to call
8991 <prgn>dpkg-gencontrol</prgn>.
8995 Sources which build several binaries will typically need
8998 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8999 </example> The <tt>-P</tt> tells
9000 <prgn>dpkg-gencontrol</prgn> that the package is being
9001 built in a non-default directory, and the <tt>-p</tt>
9002 tells it which package's control file should be generated.
9006 <prgn>dpkg-gencontrol</prgn> also adds information to the
9007 list of files in <file>debian/files</file>, for the benefit of
9008 (for example) a future invocation of
9009 <prgn>dpkg-genchanges</prgn>.</p>
9014 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9019 This program is usually called from <file>debian/rules</file>
9020 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9021 id="pkg-sourcetree">), in the top level of the source tree.
9025 Its arguments are executables.
9028 In a forthcoming dpkg version,
9029 <prgn>dpkg-shlibdeps</prgn> would be required to be
9030 called on shared libraries as well.
9033 They may be specified either in the locations in the
9034 source tree where they are created or in the locations
9035 in the temporary build tree where they are installed
9036 prior to binary package creation.
9038 </footnote> for which shared library dependencies should
9039 be included in the binary package's control file.
9043 If some of the found shared libraries should only
9044 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9045 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9046 by using the <tt>-d<var>dependency-field</var></tt> option
9047 before those executable(s). (Each <tt>-d</tt> option
9048 takes effect until the next <tt>-d</tt>.)
9052 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9053 output control file to be modified. Instead by default it
9054 adds to the <file>debian/substvars</file> file variable
9055 settings like <tt>shlibs:Depends</tt>. These variable
9056 settings must be referenced in dependency fields in the
9057 appropriate per-binary-package sections of the source
9062 For example, the <prgn>procps</prgn> package generates two
9063 kinds of binaries, simple C binaries like <prgn>ps</prgn>
9064 which require a predependency and full-screen ncurses
9065 binaries like <prgn>top</prgn> which require only a
9066 recommendation. It can say in its <file>debian/rules</file>:
9068 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
9070 and then in its main control file <file>debian/control</file>:
9074 Pre-Depends: ${shlibs:Pre-Depends}
9075 Recommends: ${shlibs:Recommends}
9081 Sources which produce several binary packages with
9082 different shared library dependency requirements can use
9083 the <tt>-p<var>varnameprefix</var></tt> option to override
9084 the default <tt>shlibs:</tt> prefix (one invocation of
9085 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9086 They can thus produce several sets of dependency
9087 variables, each of the form
9088 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9089 which can be referred to in the appropriate parts of the
9090 binary package control files.
9097 <prgn>dpkg-distaddfile</prgn> - adds a file to
9098 <file>debian/files</file>
9102 Some packages' uploads need to include files other than
9103 the source and binary package files.
9107 <prgn>dpkg-distaddfile</prgn> adds a file to the
9108 <file>debian/files</file> file so that it will be included in
9109 the <file>.changes</file> file when
9110 <prgn>dpkg-genchanges</prgn> is run.
9114 It is usually invoked from the <tt>binary</tt> target of
9115 <file>debian/rules</file>:
9117 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9119 The <var>filename</var> is relative to the directory where
9120 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9121 is usually the directory above the top level of the source
9122 tree. The <file>debian/rules</file> target should put the
9123 file there just before or just after calling
9124 <prgn>dpkg-distaddfile</prgn>.
9128 The <var>section</var> and <var>priority</var> are passed
9129 unchanged into the resulting <file>.changes</file> file.
9134 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
9139 This program is usually called by package-independent
9140 automatic building scripts such as
9141 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9146 It is usually called in the top level of a built source
9147 tree, and when invoked with no arguments will print out a
9148 straightforward <file>.changes</file> file based on the
9149 information in the source package's changelog and control
9150 file and the binary and source packages which should have
9156 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
9161 This program is used internally by
9162 <prgn>dpkg-source</prgn> et al. It may also occasionally
9163 be useful in <file>debian/rules</file> and elsewhere. It
9164 parses a changelog, <file>debian/changelog</file> by default,
9165 and prints a control-file format representation of the
9166 information in it to standard output.
9170 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
9171 information about the build and host system
9175 This program can be used manually, but is also invoked by
9176 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9177 to set environment or make variables which specify the build and
9178 host architecture for the package building process.
9183 <sect id="pkg-sourcetree">
9184 <heading>The Debianised source tree</heading>
9187 The source archive scheme described later is intended to
9188 allow a Debianised source tree with some associated control
9189 information to be reproduced and transported easily. The
9190 Debianised source tree is a version of the original program
9191 with certain files added for the benefit of the
9192 Debianisation process, and with any other changes required
9193 made to the rest of the source code and installation
9198 The extra files created for Debian are in the subdirectory
9199 <file>debian</file> of the top level of the Debianised source
9200 tree. They are described below.
9203 <sect1 id="pkg-debianrules">
9204 <heading><file>debian/rules</file> - the main building script</heading>
9207 See <ref id="debianrules">.
9212 <sect1 id="pkg-dpkgchangelog">
9213 <heading><file>debian/changelog</file></heading>
9216 See <ref id="dpkgchangelog">.
9219 <sect2><heading>Defining alternative changelog formats
9223 It is possible to use a different format to the standard
9224 one, by providing a parser for the format you wish to
9229 In order to have <tt>dpkg-parsechangelog</tt> run your
9230 parser, you must include a line within the last 40 lines
9231 of your file matching the Perl regular expression:
9232 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9233 parentheses should be the name of the format. For
9234 example, you might say:
9236 @@@ changelog-format: joebloggs @@@
9238 Changelog format names are non-empty strings of alphanumerics.
9242 If such a line exists then <tt>dpkg-parsechangelog</tt>
9243 will look for the parser as
9244 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9246 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9247 it is an error for it not to find it, or for it not to
9248 be an executable program. The default changelog format
9249 is <tt>dpkg</tt>, and a parser for it is provided with
9250 the <tt>dpkg</tt> package.
9254 The parser will be invoked with the changelog open on
9255 standard input at the start of the file. It should read
9256 the file (it may seek if it wishes) to determine the
9257 information required and return the parsed information
9258 to standard output in the form of a series of control
9259 fields in the standard format. By default it should
9260 return information about only the most recent version in
9261 the changelog; it should accept a
9262 <tt>-v<var>version</var></tt> option to return changes
9263 information from all versions present <em>strictly
9264 after</em> <var>version</var>, and it should then be an
9265 error for <var>version</var> not to be present in the
9271 <list compact="compact">
9272 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9273 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9274 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9275 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9276 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9277 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9278 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9283 If several versions are being returned (due to the use
9284 of <tt>-v</tt>), the urgency value should be of the
9285 highest urgency code listed at the start of any of the
9286 versions requested followed by the concatenated
9287 (space-separated) comments from all the versions
9288 requested; the maintainer, version, distribution and
9289 date should always be from the most recent version.
9293 For the format of the <tt>Changes</tt> field see
9294 <ref id="f-Changes">.
9298 If the changelog format which is being parsed always or
9299 almost always leaves a blank line between individual
9300 change notes these blank lines should be stripped out,
9301 so as to make the resulting output compact.
9305 If the changelog format does not contain date or package
9306 name information this information should be omitted from
9307 the output. The parser should not attempt to synthesise
9308 it or find it from other sources.
9312 If the changelog does not have the expected format the
9313 parser should exit with a nonzero exit status, rather
9314 than trying to muddle through and possibly generating
9319 A changelog parser may not interact with the user at
9325 <sect1 id="pkg-srcsubstvars">
9326 <heading><file>debian/substvars</file> and variable substitutions</heading>
9329 See <ref id="substvars">.
9335 <heading><file>debian/files</file></heading>
9338 See <ref id="debianfiles">.
9342 <sect1><heading><file>debian/tmp</file>
9346 This is the canonical temporary location for the
9347 construction of binary packages by the <tt>binary</tt>
9348 target. The directory <file>tmp</file> serves as the root of
9349 the filesystem tree as it is being constructed (for
9350 example, by using the package's upstream makefiles install
9351 targets and redirecting the output there), and it also
9352 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9353 id="pkg-bincreating">.
9357 If several binary packages are generated from the same
9358 source tree it is usual to use several
9359 <file>debian/tmp<var>something</var></file> directories, for
9360 example <file>tmp-a</file> or <file>tmp-doc</file>.
9364 Whatever <file>tmp</file> directories are created and used by
9365 <tt>binary</tt> must of course be removed by the
9366 <tt>clean</tt> target.</p></sect1>
9370 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9374 As it exists on the FTP site, a Debian source package
9375 consists of three related files. You must have the right
9376 versions of all three to be able to use them.
9381 <tag>Debian source control file - <tt>.dsc</tt></tag>
9383 This file is a control file used by <prgn>dpkg-source</prgn>
9384 to extract a source package.
9385 See <ref id="debiansourcecontrolfiles">.
9389 Original source archive -
9391 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9398 This is a compressed (with <tt>gzip -9</tt>)
9399 <prgn>tar</prgn> file containing the source code from
9400 the upstream authors of the program. The tarfile
9401 unpacks into a directory
9402 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9403 and does not contain files anywhere other than in
9404 there or in its subdirectories.</p>
9408 Debianisation diff -
9410 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9416 This is a unified context diff (<tt>diff -u</tt>)
9417 giving the changes which are required to turn the
9418 original source into the Debian source. These changes
9419 may only include editing and creating plain files.
9420 The permissions of files, the targets of symbolic
9421 links and the characteristics of special files or
9422 pipes may not be changed and no files may be removed
9427 All the directories in the diff must exist, except the
9428 <file>debian</file> subdirectory of the top of the source
9429 tree, which will be created by
9430 <prgn>dpkg-source</prgn> if necessary when unpacking.
9434 The <prgn>dpkg-source</prgn> program will
9435 automatically make the <file>debian/rules</file> file
9436 executable (see below).</p></item>
9441 If there is no original source code - for example, if the
9442 package is specially prepared for Debian or the Debian
9443 maintainer is the same as the upstream maintainer - the
9444 format is slightly different: then there is no diff, and the
9446 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9447 contains a directory
9448 <file><var>package</var>-<var>version</var></file>.
9453 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
9456 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9457 Debian source package. However, if it is not available it
9458 is possible to unpack a Debian source archive as follows:
9459 <enumlist compact="compact">
9462 Untar the tarfile, which will create a <file>.orig</file>
9466 <p>Rename the <file>.orig</file> directory to
9467 <file><var>package</var>-<var>version</var></file>.</p>
9471 Create the subdirectory <file>debian</file> at the top of
9472 the source tree.</p>
9474 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9476 <item><p>Untar the tarfile again if you want a copy of the original
9477 source code alongside the Debianised version.</p>
9482 It is not possible to generate a valid Debian source archive
9483 without using <prgn>dpkg-source</prgn>. In particular,
9484 attempting to use <prgn>diff</prgn> directly to generate the
9485 <file>.diff.gz</file> file will not work.
9489 <heading>Restrictions on objects in source packages</heading>
9492 The source package may not contain any hard links
9494 This is not currently detected when building source
9495 packages, but only when extracting
9499 Hard links may be permitted at some point in the
9500 future, but would require a fair amount of
9502 </footnote>, device special files, sockets or setuid or
9505 Setgid directories are allowed.
9510 The source packaging tools manage the changes between the
9511 original and Debianised source using <prgn>diff</prgn> and
9512 <prgn>patch</prgn>. Turning the original source tree as
9513 included in the <file>.orig.tar.gz</file> into the debianised
9514 source must not involve any changes which cannot be
9515 handled by these tools. Problematic changes which cause
9516 <prgn>dpkg-source</prgn> to halt with an error when
9517 building the source package are:
9518 <list compact="compact">
9519 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9521 <item><p>Changing the targets of symbolic links.</p>
9523 <item><p>Creating directories, other than <file>debian</file>.</p>
9525 <item><p>Changes to the contents of binary files.</p></item>
9526 </list> Changes which cause <prgn>dpkg-source</prgn> to
9527 print a warning but continue anyway are:
9528 <list compact="compact">
9531 Removing files, directories or symlinks.
9533 Renaming a file is not treated specially - it is
9534 seen as the removal of the old file (which
9535 generates a warning, but is otherwise ignored),
9536 and the creation of the new one.
9542 Changed text files which are missing the usual final
9543 newline (either in the original or the modified
9548 Changes which are not represented, but which are not detected by
9549 <prgn>dpkg-source</prgn>, are:
9550 <list compact="compact">
9551 <item><p>Changing the permissions of files (other than
9552 <file>debian/rules</file>) and directories.</p></item>
9557 The <file>debian</file> directory and <file>debian/rules</file>
9558 are handled specially by <prgn>dpkg-source</prgn> - before
9559 applying the changes it will create the <file>debian</file>
9560 directory, and afterwards it will make
9561 <file>debian/rules</file> world-exectuable.
9567 <appendix id="pkg-controlfields">
9568 <heading>Control files and their fields (from old Packaging Manual)</heading>
9571 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9572 data in a common format, known as control files. Binary and
9573 source packages have control data as do the <file>.changes</file>
9574 files which control the installation of uploaded files, and
9575 <prgn>dpkg</prgn>'s internal databases are in a similar
9580 <heading>Syntax of control files</heading>
9583 See <ref id="controlsyntax">.
9587 It is important to note that there are several fields which
9588 are optional as far as <prgn>dpkg</prgn> and the related
9589 tools are concerned, but which must appear in every Debian
9590 package, or whose omission may cause problems.
9595 <heading>List of fields</heading>
9598 See <ref id="controlfieldslist">.
9602 This section now contains only the fields that didn't belong
9603 to the Policy manual.
9606 <sect1 id="pkg-f-Filename">
9607 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
9610 These fields in <tt>Packages</tt> files give the
9611 filename(s) of (the parts of) a package in the
9612 distribution directories, relative to the root of the
9613 Debian hierarchy. If the package has been split into
9614 several parts the parts are all listed in order, separated
9619 <sect1 id="pkg-f-Size">
9620 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
9623 These fields in <file>Packages</file> files give the size (in
9624 bytes, expressed in decimal) and MD5 checksum of the
9625 file(s) which make(s) up a binary package in the
9626 distribution. If the package is split into several parts
9627 the values for the parts are listed in order, separated by
9632 <sect1 id="pkg-f-Status">
9633 <heading><tt>Status</tt></heading>
9636 This field in <prgn>dpkg</prgn>'s status file records
9637 whether the user wants a package installed, removed or
9638 left alone, whether it is broken (requiring
9639 reinstallation) or not and what its current state on the
9640 system is. Each of these pieces of information is a
9645 <sect1 id="pkg-f-Config-Version">
9646 <heading><tt>Config-Version</tt></heading>
9649 If a package is not installed or not configured, this
9650 field in <prgn>dpkg</prgn>'s status file records the last
9651 version of the package which was successfully
9656 <sect1 id="pkg-f-Conffiles">
9657 <heading><tt>Conffiles</tt></heading>
9660 This field in <prgn>dpkg</prgn>'s status file contains
9661 information about the automatically-managed configuration
9662 files held by a package. This field should <em>not</em>
9663 appear anywhere in a package!
9668 <heading>Obsolete fields</heading>
9671 These are still recognised by <prgn>dpkg</prgn> but should
9672 not appear anywhere any more.
9674 <taglist compact="compact">
9676 <tag><tt>Revision</tt></tag>
9677 <tag><tt>Package-Revision</tt></tag>
9678 <tag><tt>Package_Revision</tt></tag>
9680 The Debian revision part of the package version was
9681 at one point in a separate control file field. This
9682 field went through several names.
9685 <tag><tt>Recommended</tt></tag>
9686 <item>Old name for <tt>Recommends</tt>.</item>
9688 <tag><tt>Optional</tt></tag>
9689 <item>Old name for <tt>Suggests</tt>.</item>
9691 <tag><tt>Class</tt></tag>
9692 <item>Old name for <tt>Priority</tt>.</item>
9701 <appendix id="pkg-conffiles">
9702 <heading>Configuration file handling (from old Packaging Manual)</heading>
9705 <prgn>dpkg</prgn> can do a certain amount of automatic
9706 handling of package configuration files.
9710 Whether this mechanism is appropriate depends on a number of
9711 factors, but basically there are two approaches to any
9712 particular configuration file.
9716 The easy method is to ship a best-effort configuration in the
9717 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
9718 handle updates. If the user is unlikely to want to edit the
9719 file, but you need them to be able to without losing their
9720 changes, and a new package with a changed version of the file
9721 is only released infrequently, this is a good approach.
9725 The hard method is to build the configuration file from
9726 scratch in the <prgn>postinst</prgn> script, and to take the
9727 responsibility for fixing any mistakes made in earlier
9728 versions of the package automatically. This will be
9729 appropriate if the file is likely to need to be different on
9733 <sect><heading>Automatic handling of configuration files by
9738 A package may contain a control area file called
9739 <tt>conffiles</tt>. This file should be a list of filenames
9740 of configuration files needing automatic handling, separated
9741 by newlines. The filenames should be absolute pathnames,
9742 and the files referred to should actually exist in the
9747 When a package is upgraded <prgn>dpkg</prgn> will process
9748 the configuration files during the configuration stage,
9749 shortly before it runs the package's <prgn>postinst</prgn>
9754 For each file it checks to see whether the version of the
9755 file included in the package is the same as the one that was
9756 included in the last version of the package (the one that is
9757 being upgraded from); it also compares the version currently
9758 installed on the system with the one shipped with the last
9763 If neither the user nor the package maintainer has changed
9764 the file, it is left alone. If one or the other has changed
9765 their version, then the changed version is preferred - i.e.,
9766 if the user edits their file, but the package maintainer
9767 doesn't ship a different version, the user's changes will
9768 stay, silently, but if the maintainer ships a new version
9769 and the user hasn't edited it the new version will be
9770 installed (with an informative message). If both have
9771 changed their version the user is prompted about the problem
9772 and must resolve the differences themselves.
9776 The comparisons are done by calculating the MD5 message
9777 digests of the files, and storing the MD5 of the file as it
9778 was included in the most recent version of the package.
9782 When a package is installed for the first time
9783 <prgn>dpkg</prgn> will install the file that comes with it,
9784 unless that would mean overwriting a file already on the
9789 However, note that <prgn>dpkg</prgn> will <em>not</em>
9790 replace a conffile that was removed by the user (or by a
9791 script). This is necessary because with some programs a
9792 missing file produces an effect hard or impossible to
9793 achieve in another way, so that a missing file needs to be
9794 kept that way if the user did it.
9798 Note that a package should <em>not</em> modify a
9799 <prgn>dpkg</prgn>-handled conffile in its maintainer
9800 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
9801 the user confusing and possibly dangerous options for
9802 conffile update when the package is upgraded.</p>
9805 <sect><heading>Fully-featured maintainer script configuration
9810 For files which contain site-specific information such as
9811 the hostname and networking details and so forth, it is
9812 better to create the file in the package's
9813 <prgn>postinst</prgn> script.
9817 This will typically involve examining the state of the rest
9818 of the system to determine values and other information, and
9819 may involve prompting the user for some information which
9820 can't be obtained some other way.
9824 When using this method there are a couple of important
9825 issues which should be considered:
9829 If you discover a bug in the program which generates the
9830 configuration file, or if the format of the file changes
9831 from one version to the next, you will have to arrange for
9832 the postinst script to do something sensible - usually this
9833 will mean editing the installed configuration file to remove
9834 the problem or change the syntax. You will have to do this
9835 very carefully, since the user may have changed the file,
9836 perhaps to fix the very problem that your script is trying
9837 to deal with - you will have to detect these situations and
9838 deal with them correctly.
9842 If you do go down this route it's probably a good idea to
9843 make the program that generates the configuration file(s) a
9844 separate program in <file>/usr/sbin</file>, by convention called
9845 <file><var>package</var>config</file> and then run that if
9846 appropriate from the post-installation script. The
9847 <tt><var>package</var>config</tt> program should not
9848 unquestioningly overwrite an existing configuration - if its
9849 mode of operation is geared towards setting up a package for
9850 the first time (rather than any arbitrary reconfiguration
9851 later) you should have it check whether the configuration
9852 already exists, and require a <tt>--force</tt> flag to
9853 overwrite it.</p></sect>
9856 <appendix id="pkg-alternatives"><heading>Alternative versions of
9857 an interface - <prgn>update-alternatives</prgn> (from old
9862 When several packages all provide different versions of the
9863 same program or file it is useful to have the system select a
9864 default, but to allow the system administrator to change it
9865 and have their decisions respected.
9869 For example, there are several versions of the <prgn>vi</prgn>
9870 editor, and there is no reason to prevent all of them from
9871 being installed at once, each under their own name
9872 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
9873 Nevertheless it is desirable to have the name <tt>vi</tt>
9874 refer to something, at least by default.
9878 If all the packages involved cooperate, this can be done with
9879 <prgn>update-alternatives</prgn>.
9883 Each package provides its own version under its own name, and
9884 calls <prgn>update-alternatives</prgn> in its postinst to
9885 register its version (and again in its prerm to deregister
9890 See the manpage <manref name="update-alternatives"
9891 section="8"> for details.
9895 If <prgn>update-alternatives</prgn> does not seem appropriate
9896 you may wish to consider using diversions instead.</p>
9899 <appendix id="pkg-diversions"><heading>Diversions - overriding a
9900 package's version of a file (from old Packaging Manual)
9904 It is possible to have <prgn>dpkg</prgn> not overwrite a file
9905 when it reinstalls the package it belongs to, and to have it
9906 put the file from the package somewhere else instead.
9910 This can be used locally to override a package's version of a
9911 file, or by one package to override another's version (or
9912 provide a wrapper for it).
9916 Before deciding to use a diversion, read <ref
9917 id="pkg-alternatives"> to see if you really want a diversion
9918 rather than several alternative versions of a program.
9922 There is a diversion list, which is read by <prgn>dpkg</prgn>,
9923 and updated by a special program <prgn>dpkg-divert</prgn>.
9924 Please see <manref name="dpkg-divert" section="8"> for full
9925 details of its operation.
9929 When a package wishes to divert a file from another, it should
9930 call <prgn>dpkg-divert</prgn> in its preinst to add the
9931 diversion and rename the existing file. For example,
9932 supposing that a <prgn>smailwrapper</prgn> package wishes to
9933 install a wrapper around <file>/usr/sbin/smail</file>:
9935 if [ install = "$1" ]; then
9936 dpkg-divert --package smailwrapper --add --rename \
9937 --divert /usr/sbin/smail.real /usr/sbin/smail
9939 </example> Testing <tt>$1</tt> is necessary so that the script
9940 doesn't try to add the diversion again when
9941 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
9942 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
9943 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
9944 get installed as the true version.
9948 The postrm has to do the reverse:
9950 if [ remove = "$1" ]; then
9951 dpkg-divert --package smailwrapper --remove --rename \
9952 --divert /usr/sbin/smail.real /usr/sbin/smail
9958 Do not attempt to divert a file which is vitally important for
9959 the system's operation - when using <prgn>dpkg-divert</prgn>
9960 there is a time, after it has been diverted but before
9961 <prgn>dpkg</prgn> has installed the new version, when the file
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