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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 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interfaces not changing, and the package
94 management software authors need to ensure
95 compatibility with these interface
96 definitions. (Control file and changelog file
97 formats are examples.)
99 <tag>Chosen Convention</tag>
101 If there are a number of technically viable choices
102 that can be made, but one needs to select one of
103 these options for inter-operability. The version
104 number format is one example.
107 Please note that these are not mutually exclusive;
108 selected conventions often become parts of standard
114 The footnotes present in this manual are
115 merely informative, and are not part of Debian policy itself.
119 The appendices to this manual are not necessarily normative,
120 either. Please see <ref id="pkg-scope"> for more information.
124 In the normative part of this manual,
125 the words <em>must</em>, <em>should</em> and
126 <em>may</em>, and the adjectives <em>required</em>,
127 <em>recommended</em> and <em>optional</em>, are used to
128 distinguish the significance of the various guidelines in
129 this policy document. Packages that do not conform to the
130 guidelines denoted by <em>must</em> (or <em>required</em>)
131 will generally not be considered acceptable for the Debian
132 distribution. Non-conformance with guidelines denoted by
133 <em>should</em> (or <em>recommended</em>) will generally be
134 considered a bug, but will not necessarily render a package
135 unsuitable for distribution. Guidelines denoted by
136 <em>may</em> (or <em>optional</em>) are truly optional and
137 adherence is left to the maintainer's discretion.
141 These classifications are roughly equivalent to the bug
142 severities <em>serious</em> (for <em>must</em> or
143 <em>required</em> directive violations), <em>minor</em>,
144 <em>normal</em> or <em>important</em>
145 (for <em>should</em> or <em>recommended</em> directive
146 violations) and <em>wishlist</em> (for <em>optional</em>
149 Compare RFC 2119. Note, however, that these words are
150 used in a different way in this document.
155 Much of the information presented in this manual will be
156 useful even when building a package which is to be
157 distributed in some other way or is intended for local use
163 <heading>New versions of this document</heading>
166 This manual is distributed via the Debian package
167 <package><url name="debian-policy"
168 id="http://packages.debian.org/debian-policy"></package>
169 (<httpsite>packages.debian.org</httpsite>
170 <httppath>/debian-policy</httppath>).
174 The current version of this document is also available from
175 the Debian web mirrors at
176 <tt><url name="/doc/debian-policy/"
177 id="http://www.debian.org/doc/debian-policy/"></tt>.
179 <httpsite>www.debian.org</httpsite>
180 <httppath>/doc/debian-policy/</httppath>)
181 Also available from the same directory are several other
182 formats: <file>policy.html.tar.gz</file>
183 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
184 <file>policy.pdf.gz</file>
185 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
186 and <file>policy.ps.gz</file>
187 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
191 The <package>debian-policy</package> package also includes the file
192 <file>upgrading-checklist.txt.gz</file> which indicates policy
193 changes between versions of this document.
198 <heading>Authors and Maintainers</heading>
201 Originally called "Debian GNU/Linux Policy Manual", this
202 manual was initially written in 1996 by Ian Jackson.
203 It was revised on November 27th, 1996 by David A. Morris.
204 Christian Schwarz added new sections on March 15th, 1997,
205 and reworked/restructured it in April-July 1997.
206 Christoph Lameter contributed the "Web Standard".
207 Julian Gilbey largely restructured it in 2001.
211 Since September 1998, the responsibility for the contents of
212 this document lies on the <url name="debian-policy mailing list"
213 id="mailto:debian-policy@lists.debian.org">. Proposals
214 are discussed there and inserted into policy after a certain
215 consensus is established.
216 <!-- insert shameless policy-process plug here eventually -->
217 The actual editing is done by a group of maintainers that have
218 no editorial powers. These are the current maintainers:
221 <item>Julian Gilbey</item>
222 <item>Branden Robinson</item>
223 <item>Josip Rodin</item>
224 <item>Manoj Srivastava</item>
229 While the authors of this document have tried hard to avoid
230 typos and other errors, these do still occur. If you discover
231 an error in this manual or if you want to give any
232 comments, suggestions, or criticisms please send an email to
233 the Debian Policy List,
234 <email>debian-policy@lists.debian.org</email>, or submit a
235 bug report against the <tt>debian-policy</tt> package.
239 Please do not try to reach the individual authors or maintainers
240 of the Policy Manual regarding changes to the Policy.
245 <heading>Related documents</heading>
248 There are several other documents other than this Policy Manual
249 that are necessary to fully understand some Debian policies and
254 The external "sub-policy" documents are referred to in:
255 <list compact="compact">
256 <item><ref id="fhs"></item>
257 <item><ref id="virtual_pkg"></item>
258 <item><ref id="menus"></item>
259 <item><ref id="mime"></item>
260 <item><ref id="perl"></item>
261 <item><ref id="maintscriptprompt"></item>
262 <item><ref id="emacs"></item>
267 In addition to those, which carry the weight of policy, there
268 is the Debian Developer's Reference. This document describes
269 procedures and resources for Debian developers, but it is
270 <em>not</em> normative; rather, it includes things that don't
271 belong in the Policy, such as best practices for developers.
275 The Developer's Reference is available in the
276 <package>developers-reference</package> package.
277 It's also available from the Debian web mirrors at
278 <tt><url name="/doc/developers-reference/"
279 id="http://www.debian.org/doc/developers-reference/"></tt>.
283 <sect id="definitions">
284 <heading>Definitions</heading>
287 The following terms are used in this Policy Manual:
291 The character encoding specified by ANSI X3.4-1986 and its
292 predecessor standards, referred to in MIME as US-ASCII, and
293 corresponding to an encoding in eight bits per character of
294 the first 128 <url id="http://www.unicode.org/"
295 name="Unicode"> characters, with the eighth bit always zero.
299 The transformation format (sometimes called encoding) of
300 <url id="http://www.unicode.org/" name="Unicode"> defined by
301 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
302 name="RFC 3629">. UTF-8 has the useful property of having
303 ASCII as a subset, so any text encoded in ASCII is trivially
313 <heading>The Debian Archive</heading>
316 The Debian GNU/Linux system is maintained and distributed as a
317 collection of <em>packages</em>. Since there are so many of
318 them (currently well over 15000), they are split into
319 <em>sections</em> and given <em>priorities</em> to simplify
320 the handling of them.
324 The effort of the Debian project is to build a free operating
325 system, but not every package we want to make accessible is
326 <em>free</em> in our sense (see the Debian Free Software
327 Guidelines, below), or may be imported/exported without
328 restrictions. Thus, the archive is split into areas<footnote>
329 The Debian archive software uses the term "component" internally
330 and in the Release file format to refer to the division of an
331 archive. The Debian Social Contract simply refers to "areas."
332 This document uses terminology similar to the Social Contract.
333 </footnote> based on their licenses and other restrictions.
337 The aims of this are:
339 <list compact="compact">
340 <item>to allow us to make as much software available as we can</item>
341 <item>to allow us to encourage everyone to write free software,
343 <item>to allow us to make it easy for people to produce
344 CD-ROMs of our system without violating any licenses,
345 import/export restrictions, or any other laws.</item>
350 The <em>main</em> archive area forms the <em>Debian GNU/Linux
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 Every package in <em>main</em> must comply with the DFSG
469 (Debian Free Software Guidelines).
473 In addition, the packages in <em>main</em>
474 <list compact="compact">
476 must not require a package outside of <em>main</em>
477 for compilation or execution (thus, the package must
478 not declare a "Depends", "Recommends", or
479 "Build-Depends" relationship on a non-<em>main</em>
483 must not be so buggy that we refuse to support them,
487 must meet all policy requirements presented in this
496 <heading>The contrib archive area</heading>
499 Every package in <em>contrib</em> must comply with the DFSG.
503 In addition, the packages in <em>contrib</em>
504 <list compact="compact">
506 must not be so buggy that we refuse to support them,
510 must meet all policy requirements presented in this
518 Examples of packages which would be included in
519 <em>contrib</em> are:
520 <list compact="compact">
522 free packages which require <em>contrib</em>,
523 <em>non-free</em> packages or packages which are not
524 in our archive at all for compilation or execution,
528 wrapper packages or other sorts of free accessories for
535 <sect1 id="non-free">
536 <heading>The non-free archive area</heading>
539 Packages must be placed in <em>non-free</em> if they are
540 not compliant with the DFSG or are encumbered by patents
541 or other legal issues that make their distribution
546 In addition, the packages in <em>non-free</em>
547 <list compact="compact">
549 must not be so buggy that we refuse to support them,
553 must meet all policy requirements presented in this
554 manual that it is possible for them to meet.
556 It is possible that there are policy
557 requirements which the package is unable to
558 meet, for example, if the source is
559 unavailable. These situations will need to be
560 handled on a case-by-case basis.
569 <sect id="pkgcopyright">
570 <heading>Copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of
574 its copyright and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
580 We reserve the right to restrict files from being included
581 anywhere in our archives if
582 <list compact="compact">
584 their use or distribution would break a law,
587 there is an ethical conflict in their distribution or
591 we would have to sign a license for them, or
594 their distribution would conflict with other project
601 Programs whose authors encourage the user to make
602 donations are fine for the main distribution, provided
603 that the authors do not claim that not donating is
604 immoral, unethical, illegal or something similar; in such
605 a case they must go in <em>non-free</em>.
609 Packages whose copyright permission notices (or patent
610 problems) do not even allow redistribution of binaries
611 only, and where no special permission has been obtained,
612 must not be placed on the Debian FTP site and its mirrors
617 Note that under international copyright law (this applies
618 in the United States, too), <em>no</em> distribution or
619 modification of a work is allowed without an explicit
620 notice saying so. Therefore a program without a copyright
621 notice <em>is</em> copyrighted and you may not do anything
622 to it without risking being sued! Likewise if a program
623 has a copyright notice but no statement saying what is
624 permitted then nothing is permitted.
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <sect id="subsections">
649 <heading>Sections</heading>
652 The packages in the archive areas <em>main</em>,
653 <em>contrib</em> and <em>non-free</em> are grouped further into
654 <em>sections</em> to simplify handling.
658 The archive area and section for each package should be
659 specified in the package's <tt>Section</tt> control record (see
660 <ref id="f-Section">). However, the maintainer of the Debian
661 archive may override this selection to ensure the consistency of
662 the Debian distribution. The <tt>Section</tt> field should be
664 <list compact="compact">
666 <em>section</em> if the package is in the
667 <em>main</em> archive area,
670 <em>area/section</em> if the package is in
671 the <em>contrib</em> or <em>non-free</em>
678 The Debian archive maintainers provide the authoritative
679 list of sections. At present, they are:
680 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
681 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
682 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
683 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
684 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
685 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
686 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
687 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
688 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
689 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
690 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
691 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
692 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
697 <sect id="priorities">
698 <heading>Priorities</heading>
701 Each package should have a <em>priority</em> value, which is
702 included in the package's <em>control record</em>
703 (see <ref id="f-Priority">).
704 This information is used by the Debian package management tools to
705 separate high-priority packages from less-important packages.
709 The following <em>priority levels</em> are recognized by the
710 Debian package management tools.
712 <tag><tt>required</tt></tag>
714 Packages which are necessary for the proper
715 functioning of the system (usually, this means that
716 dpkg functionality depends on these packages).
717 Removing a <tt>required</tt> package may cause your
718 system to become totally broken and you may not even
719 be able to use <prgn>dpkg</prgn> to put things back,
720 so only do so if you know what you are doing. Systems
721 with only the <tt>required</tt> packages are probably
722 unusable, but they do have enough functionality to
723 allow the sysadmin to boot and install more software.
725 <tag><tt>important</tt></tag>
727 Important programs, including those which one would
728 expect to find on any Unix-like system. If the
729 expectation is that an experienced Unix person who
730 found it missing would say "What on earth is going on,
731 where is <prgn>foo</prgn>?", it must be an
732 <tt>important</tt> package.<footnote>
733 This is an important criterion because we are
734 trying to produce, amongst other things, a free
737 Other packages without which the system will not run
738 well or be usable must also have priority
739 <tt>important</tt>. This does
740 <em>not</em> include Emacs, the X Window System, TeX
741 or any other large applications. The
742 <tt>important</tt> packages are just a bare minimum of
743 commonly-expected and necessary tools.
745 <tag><tt>standard</tt></tag>
747 These packages provide a reasonably small but not too
748 limited character-mode system. This is what will be
749 installed by default if the user doesn't select anything
750 else. It doesn't include many large applications.
752 <tag><tt>optional</tt></tag>
754 (In a sense everything that isn't required is
755 optional, but that's not what is meant here.) This is
756 all the software that you might reasonably want to
757 install if you didn't know what it was and don't have
758 specialized requirements. This is a much larger system
759 and includes the X Window System, a full TeX
760 distribution, and many applications. Note that
761 optional packages should not conflict with each other.
763 <tag><tt>extra</tt></tag>
765 This contains all packages that conflict with others
766 with required, important, standard or optional
767 priorities, or are only likely to be useful if you
768 already know what they are or have specialized
769 requirements (such as packages containing only detached
776 Packages must not depend on packages with lower priority
777 values (excluding build-time dependencies). In order to
778 ensure this, the priorities of one or more packages may need
787 <heading>Binary packages</heading>
790 The Debian GNU/Linux distribution is based on the Debian
791 package management system, called <prgn>dpkg</prgn>. Thus,
792 all packages in the Debian distribution must be provided
793 in the <tt>.deb</tt> file format.
797 <heading>The package name</heading>
800 Every package must have a name that's unique within the Debian
805 The package name is included in the control field
806 <tt>Package</tt>, the format of which is described
807 in <ref id="f-Package">.
808 The package name is also included as a part of the file name
809 of the <tt>.deb</tt> file.
814 <heading>The version of a package</heading>
817 Every package has a version number recorded in its
818 <tt>Version</tt> control file field, described in
819 <ref id="f-Version">.
823 The package management system imposes an ordering on version
824 numbers, so that it can tell whether packages are being up- or
825 downgraded and so that package system front end applications
826 can tell whether a package it finds available is newer than
827 the one installed on the system. The version number format
828 has the most significant parts (as far as comparison is
829 concerned) at the beginning.
833 If an upstream package has problematic version numbers they
834 should be converted to a sane form for use in the
835 <tt>Version</tt> field.
839 <heading>Version numbers based on dates</heading>
842 In general, Debian packages should use the same version
843 numbers as the upstream sources.
847 However, in some cases where the upstream version number is
848 based on a date (e.g., a development "snapshot" release) the
849 package management system cannot handle these version
850 numbers without epochs. For example, dpkg will consider
851 "96May01" to be greater than "96Dec24".
855 To prevent having to use epochs for every new upstream
856 version, the date based portion of the version number
857 should be changed to the following format in such cases:
858 "19960501", "19961224". It is up to the maintainer whether
859 they want to bother the upstream maintainer to change
860 the version numbers upstream, too.
864 Note that other version formats based on dates which are
865 parsed correctly by the package management system should
866 <em>not</em> be changed.
870 Native Debian packages (i.e., packages which have been
871 written especially for Debian) whose version numbers include
872 dates should always use the "YYYYMMDD" format.
879 <heading>The maintainer of a package</heading>
882 Every package must have a Debian maintainer (the
883 maintainer may be one person or a group of people
884 reachable from a common email address, such as a mailing
885 list). The maintainer is responsible for ensuring that
886 the package is placed in the appropriate distributions.
890 The maintainer must be specified in the
891 <tt>Maintainer</tt> control field with their correct name
892 and a working email address. If one person maintains
893 several packages, they should try to avoid having
894 different forms of their name and email address in
895 the <tt>Maintainer</tt> fields of those packages.
899 The format of the <tt>Maintainer</tt> control field is
900 described in <ref id="f-Maintainer">.
904 If the maintainer of a package quits from the Debian
905 project, "Debian QA Group"
906 <email>packages@qa.debian.org</email> takes over the
907 maintainer-ship of the package until someone else
908 volunteers for that task. These packages are called
909 <em>orphaned packages</em>.<footnote>
910 The detailed procedure for doing this gracefully can
911 be found in the Debian Developer's Reference,
912 see <ref id="related">.
917 <sect id="descriptions">
918 <heading>The description of a package</heading>
921 Every Debian package must have an extended description
922 stored in the appropriate field of the control record.
923 The technical information about the format of the
924 <tt>Description</tt> field is in <ref id="f-Description">.
928 The description should describe the package (the program) to a
929 user (system administrator) who has never met it before so that
930 they have enough information to decide whether they want to
931 install it. This description should not just be copied verbatim
932 from the program's documentation.
936 Put important information first, both in the synopsis and
937 extended description. Sometimes only the first part of the
938 synopsis or of the description will be displayed. You can
939 assume that there will usually be a way to see the whole
940 extended description.
944 The description should also give information about the
945 significant dependencies and conflicts between this package
946 and others, so that the user knows why these dependencies and
947 conflicts have been declared.
951 Instructions for configuring or using the package should
952 not be included (that is what installation scripts,
953 manual pages, info files, etc., are for). Copyright
954 statements and other administrivia should not be included
955 either (that is what the copyright file is for).
958 <sect1 id="synopsis"><heading>The single line synopsis</heading>
961 The single line synopsis should be kept brief - certainly
966 Do not include the package name in the synopsis line. The
967 display software knows how to display this already, and you
968 do not need to state it. Remember that in many situations
969 the user may only see the synopsis line - make it as
970 informative as you can.
975 <sect1 id="extendeddesc"><heading>The extended description</heading>
978 Do not try to continue the single line synopsis into the
979 extended description. This will not work correctly when
980 the full description is displayed, and makes no sense
981 where only the summary (the single line synopsis) is
986 The extended description should describe what the package
987 does and how it relates to the rest of the system (in terms
988 of, for example, which subsystem it is which part of).
992 The description field needs to make sense to anyone, even
993 people who have no idea about any of the things the
994 package deals with.<footnote>
995 The blurb that comes with a program in its
996 announcements and/or <prgn>README</prgn> files is
997 rarely suitable for use in a description. It is
998 usually aimed at people who are already in the
999 community where the package is used.
1008 <heading>Dependencies</heading>
1011 Every package must specify the dependency information
1012 about other packages that are required for the first to
1017 For example, a dependency entry must be provided for any
1018 shared libraries required by a dynamically-linked executable
1019 binary in a package.
1023 Packages are not required to declare any dependencies they
1024 have on other packages which are marked <tt>Essential</tt>
1025 (see below), and should not do so unless they depend on a
1026 particular version of that package.<footnote>
1028 Essential is needed in part to avoid unresolvable dependency
1029 loops on upgrade. If packages add unnecessary dependencies
1030 on packages in this set, the chances that there
1031 <strong>will</strong> be an unresolvable dependency loop
1032 caused by forcing these Essential packages to be configured
1033 first before they need to be is greatly increased. It also
1034 increases the chances that frontends will be unable to
1035 <strong>calculate</strong> an upgrade path, even if one
1039 Also, functionality is rarely ever removed from the
1040 Essential set, but <em>packages</em> have been removed from
1041 the Essential set when the functionality moved to a
1042 different package. So depending on these packages <em>just
1043 in case</em> they stop being essential does way more harm
1050 Sometimes, a package requires another package to be installed
1051 <em>and</em> configured before it can be installed. In this
1052 case, you must specify a <tt>Pre-Depends</tt> entry for
1057 You should not specify a <tt>Pre-Depends</tt> entry for a
1058 package before this has been discussed on the
1059 <tt>debian-devel</tt> mailing list and a consensus about
1060 doing that has been reached.
1064 The format of the package interrelationship control fields is
1065 described in <ref id="relationships">.
1069 <sect id="virtual_pkg">
1070 <heading>Virtual packages</heading>
1073 Sometimes, there are several packages which offer
1074 more-or-less the same functionality. In this case, it's
1075 useful to define a <em>virtual package</em> whose name
1076 describes that common functionality. (The virtual
1077 packages only exist logically, not physically; that's why
1078 they are called <em>virtual</em>.) The packages with this
1079 particular function will then <em>provide</em> the virtual
1080 package. Thus, any other package requiring that function
1081 can simply depend on the virtual package without having to
1082 specify all possible packages individually.
1086 All packages should use virtual package names where
1087 appropriate, and arrange to create new ones if necessary.
1088 They should not use virtual package names (except privately,
1089 amongst a cooperating group of packages) unless they have
1090 been agreed upon and appear in the list of virtual package
1091 names. (See also <ref id="virtual">)
1095 The latest version of the authoritative list of virtual
1096 package names can be found in the <tt>debian-policy</tt> package.
1097 It is also available from the Debian web mirrors at
1098 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1099 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1103 The procedure for updating the list is described in the preface
1110 <heading>Base system</heading>
1113 The <tt>base system</tt> is a minimum subset of the Debian
1114 GNU/Linux system that is installed before everything else
1115 on a new system. Only very few packages are allowed to form
1116 part of the base system, in order to keep the required disk
1121 The base system consists of all those packages with priority
1122 <tt>required</tt> or <tt>important</tt>. Many of them will
1123 be tagged <tt>essential</tt> (see below).
1128 <heading>Essential packages</heading>
1131 Essential is defined as the minimal set of functionality that
1132 must be available and usable on the system at all times, even
1133 when packages are in an unconfigured (but unpacked) state.
1134 Packages are tagged <tt>essential</tt> for a system using the
1135 <tt>Essential</tt> control file field. The format of the
1136 <tt>Essential</tt> control field is described in <ref
1141 Since these packages cannot be easily removed (one has to
1142 specify an extra <em>force option</em> to
1143 <prgn>dpkg</prgn> to do so), this flag must not be used
1144 unless absolutely necessary. A shared library package
1145 must not be tagged <tt>essential</tt>; dependencies will
1146 prevent its premature removal, and we need to be able to
1147 remove it when it has been superseded.
1151 Since dpkg will not prevent upgrading of other packages
1152 while an <tt>essential</tt> package is in an unconfigured
1153 state, all <tt>essential</tt> packages must supply all of
1154 their core functionality even when unconfigured. If the
1155 package cannot satisfy this requirement it must not be
1156 tagged as essential, and any packages depending on this
1157 package must instead have explicit dependency fields as
1162 Maintainers should take great care in adding any programs,
1163 interfaces, or functionality to <tt>essential</tt> packages.
1164 Packages may assume that functionality provided by
1165 <tt>essential</tt> packages is always available without
1166 declaring explicit dependencies, which means that removing
1167 functionality from the Essential set is very difficult and is
1168 almost never done. Any capability added to an
1169 <tt>essential</tt> package therefore creates an obligation to
1170 support that capability as part of the Essential set in
1175 You must not tag any packages <tt>essential</tt> before
1176 this has been discussed on the <tt>debian-devel</tt>
1177 mailing list and a consensus about doing that has been
1182 <sect id="maintscripts">
1183 <heading>Maintainer Scripts</heading>
1186 The package installation scripts should avoid producing
1187 output which is unnecessary for the user to see and
1188 should rely on <prgn>dpkg</prgn> to stave off boredom on
1189 the part of a user installing many packages. This means,
1190 amongst other things, using the <tt>--quiet</tt> option on
1191 <prgn>install-info</prgn>.
1195 Errors which occur during the execution of an installation
1196 script must be checked and the installation must not
1197 continue after an error.
1201 Note that in general <ref id="scripts"> applies to package
1202 maintainer scripts, too.
1206 You should not use <prgn>dpkg-divert</prgn> on a file
1207 belonging to another package without consulting the
1208 maintainer of that package first.
1212 All packages which supply an instance of a common command
1213 name (or, in general, filename) should generally use
1214 <prgn>update-alternatives</prgn>, so that they may be
1215 installed together. If <prgn>update-alternatives</prgn>
1216 is not used, then each package must use
1217 <tt>Conflicts</tt> to ensure that other packages are
1218 de-installed. (In this case, it may be appropriate to
1219 specify a conflict against earlier versions of something
1220 that previously did not use
1221 <prgn>update-alternatives</prgn>; this is an exception to
1222 the usual rule that versioned conflicts should be
1226 <sect1 id="maintscriptprompt">
1227 <heading>Prompting in maintainer scripts</heading>
1229 Package maintainer scripts may prompt the user if
1230 necessary. Prompting must be done by communicating
1231 through a program, such as <prgn>debconf</prgn>, which
1232 conforms to the Debian Configuration Management
1233 Specification, version 2 or higher.
1237 Packages which are essential, or which are dependencies of
1238 essential packages, may fall back on another prompting method
1239 if no such interface is available when they are executed.
1243 The Debian Configuration Management Specification is included
1244 in the <file>debconf_specification</file> files in the
1245 <package>debian-policy</package> package.
1246 It is also available from the Debian web mirrors at
1247 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1248 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1252 Packages which use the Debian Configuration Management
1253 Specification may contain an additional
1254 <prgn>config</prgn> script and a <tt>templates</tt>
1255 file in their control archive<footnote>
1256 The control.tar.gz inside the .deb.
1257 See <manref name="deb" section="5">.
1259 The <prgn>config</prgn> script might be run before the
1260 <prgn>preinst</prgn> script, and before the package is unpacked
1261 or any of its dependencies or pre-dependencies are satisfied.
1262 Therefore it must work using only the tools present in
1263 <em>essential</em> packages.<footnote>
1264 <package>Debconf</package> or another tool that
1265 implements the Debian Configuration Management
1266 Specification will also be installed, and any
1267 versioned dependencies on it will be satisfied
1268 before preconfiguration begins.
1273 Packages which use the Debian Configuration Management
1274 Specification must allow for translation of their user-visible
1275 messages by using a gettext-based system such as the one
1276 provided by the <package>po-debconf</package> package.
1280 Packages should try to minimize the amount of prompting
1281 they need to do, and they should ensure that the user
1282 will only ever be asked each question once. This means
1283 that packages should try to use appropriate shared
1284 configuration files (such as <file>/etc/papersize</file> and
1285 <file>/etc/news/server</file>), and shared
1286 <package>debconf</package> variables rather than each
1287 prompting for their own list of required pieces of
1292 It also means that an upgrade should not ask the same
1293 questions again, unless the user has used
1294 <tt>dpkg --purge</tt> to remove the package's configuration.
1295 The answers to configuration questions should be stored in an
1296 appropriate place in <file>/etc</file> so that the user can
1297 modify them, and how this has been done should be
1302 If a package has a vitally important piece of
1303 information to pass to the user (such as "don't run me
1304 as I am, you must edit the following configuration files
1305 first or you risk your system emitting badly-formatted
1306 messages"), it should display this in the
1307 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1308 prompt the user to hit return to acknowledge the
1309 message. Copyright messages do not count as vitally
1310 important (they belong in
1311 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1312 neither do instructions on how to use a program (these
1313 should be in on-line documentation, where all the users
1318 Any necessary prompting should almost always be confined
1319 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1320 script. If it is done in the <prgn>postinst</prgn>, it
1321 should be protected with a conditional so that
1322 unnecessary prompting doesn't happen if a package's
1323 installation fails and the <prgn>postinst</prgn> is
1324 called with <tt>abort-upgrade</tt>,
1325 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1335 <heading>Source packages</heading>
1337 <sect id="standardsversion">
1338 <heading>Standards conformance</heading>
1341 Source packages should specify the most recent version number
1342 of this policy document with which your package complied
1343 when it was last updated.
1347 This information may be used to file bug reports
1348 automatically if your package becomes too much out of date.
1352 The version is specified in the <tt>Standards-Version</tt>
1354 The format of the <tt>Standards-Version</tt> field is
1355 described in <ref id="f-Standards-Version">.
1359 You should regularly, and especially if your package has
1360 become out of date, check for the newest Policy Manual
1361 available and update your package, if necessary. When your
1362 package complies with the new standards you should update the
1363 <tt>Standards-Version</tt> source package field and
1364 release it.<footnote>
1365 See the file <file>upgrading-checklist</file> for
1366 information about policy which has changed between
1367 different versions of this document.
1373 <sect id="pkg-relations">
1374 <heading>Package relationships</heading>
1377 Source packages should specify which binary packages they
1378 require to be installed or not to be installed in order to
1379 build correctly. For example, if building a package
1380 requires a certain compiler, then the compiler should be
1381 specified as a build-time dependency.
1385 It is not necessary to explicitly specify build-time
1386 relationships on a minimal set of packages that are always
1387 needed to compile, link and put in a Debian package a
1388 standard "Hello World!" program written in C or C++. The
1389 required packages are called <em>build-essential</em>, and
1390 an informational list can be found in
1391 <file>/usr/share/doc/build-essential/list</file> (which is
1392 contained in the <tt>build-essential</tt>
1395 <list compact="compact">
1397 This allows maintaining the list separately
1398 from the policy documents (the list does not
1399 need the kind of control that the policy
1403 Having a separate package allows one to install
1404 the build-essential packages on a machine, as
1405 well as allowing other packages such as tasks to
1406 require installation of the build-essential
1407 packages using the depends relation.
1410 The separate package allows bug reports against
1411 the list to be categorized separately from
1412 the policy management process in the BTS.
1419 When specifying the set of build-time dependencies, one
1420 should list only those packages explicitly required by the
1421 build. It is not necessary to list packages which are
1422 required merely because some other package in the list of
1423 build-time dependencies depends on them.<footnote>
1424 The reason for this is that dependencies change, and
1425 you should list all those packages, and <em>only</em>
1426 those packages that <em>you</em> need directly. What
1427 others need is their business. For example, if you
1428 only link against <file>libimlib</file>, you will need to
1429 build-depend on <package>libimlib2-dev</package> but
1430 not against any <tt>libjpeg*</tt> packages, even
1431 though <tt>libimlib2-dev</tt> currently depends on
1432 them: installation of <package>libimlib2-dev</package>
1433 will automatically ensure that all of its run-time
1434 dependencies are satisfied.
1439 If build-time dependencies are specified, it must be
1440 possible to build the package and produce working binaries
1441 on a system with only essential and build-essential
1442 packages installed and also those required to satisfy the
1443 build-time relationships (including any implied
1444 relationships). In particular, this means that version
1445 clauses should be used rigorously in build-time
1446 relationships so that one cannot produce bad or
1447 inconsistently configured packages when the relationships
1448 are properly satisfied.
1452 <ref id="relationships"> explains the technical details.
1457 <heading>Changes to the upstream sources</heading>
1460 If changes to the source code are made that are not
1461 specific to the needs of the Debian system, they should be
1462 sent to the upstream authors in whatever form they prefer
1463 so as to be included in the upstream version of the
1468 If you need to configure the package differently for
1469 Debian or for Linux, and the upstream source doesn't
1470 provide a way to do so, you should add such configuration
1471 facilities (for example, a new <prgn>autoconf</prgn> test
1472 or <tt>#define</tt>) and send the patch to the upstream
1473 authors, with the default set to the way they originally
1474 had it. You can then easily override the default in your
1475 <file>debian/rules</file> or wherever is appropriate.
1479 You should make sure that the <prgn>configure</prgn> utility
1480 detects the correct architecture specification string
1481 (refer to <ref id="arch-spec"> for details).
1485 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1486 <prgn>configure</prgn> scripts are used, you should edit the
1487 <file>.in</file> files rather than editing the
1488 <prgn>Makefile</prgn> directly. This allows the user to
1489 reconfigure the package if necessary. You should
1490 <em>not</em> configure the package and edit the generated
1491 <prgn>Makefile</prgn>! This makes it impossible for someone
1492 else to later reconfigure the package without losing the
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>.<footnote>
1506 Mistakes in changelogs are usually best rectified by
1507 making a new changelog entry rather than "rewriting
1508 history" by editing old changelog entries.
1511 This includes modifications
1512 made in the Debian package compared to the upstream one
1513 as well as other changes and updates to the package.
1515 Although there is nothing stopping an author who is also
1516 the Debian maintainer from using this changelog for all
1517 their changes, it will have to be renamed if the Debian
1518 and upstream maintainers become different people. In such
1519 a case, however, it might be better to maintain the package
1520 as a non-native package.
1525 The format of the <file>debian/changelog</file> allows the
1526 package building tools to discover which version of the package
1527 is being built and find out other release-specific information.
1531 That format is a series of entries like this:
1533 <example compact="compact">
1534 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1536 [optional blank line(s), stripped]
1538 * <var>change details</var>
1539 <var>more change details</var>
1541 [blank line(s), included in output of dpkg-parsechangelog]
1543 * <var>even more change details</var>
1545 [optional blank line(s), stripped]
1547 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1552 <var>package</var> and <var>version</var> are the source
1553 package name and version number.
1557 <var>distribution(s)</var> lists the distributions where
1558 this version should be installed when it is uploaded - it
1559 is copied to the <tt>Distribution</tt> field in the
1560 <file>.changes</file> file. See <ref id="f-Distribution">.
1564 <var>urgency</var> is the value for the <tt>Urgency</tt>
1565 field in the <file>.changes</file> file for the upload
1566 (see <ref id="f-Urgency">). It is not possible to specify
1567 an urgency containing commas; commas are used to separate
1568 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1569 <prgn>dpkg</prgn> changelog format (though there is
1570 currently only one useful <var>keyword</var>,
1575 The change details may in fact be any series of lines
1576 starting with at least two spaces, but conventionally each
1577 change starts with an asterisk and a separating space and
1578 continuation lines are indented so as to bring them in
1579 line with the start of the text above. Blank lines may be
1580 used here to separate groups of changes, if desired.
1584 If this upload resolves bugs recorded in the Bug Tracking
1585 System (BTS), they may be automatically closed on the
1586 inclusion of this package into the Debian archive by
1587 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1588 in the change details.<footnote>
1589 To be precise, the string should match the following
1590 Perl regular expression:
1592 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1594 Then all of the bug numbers listed will be closed by the
1595 archive maintenance script (<prgn>katie</prgn>) using the
1596 <var>version</var> of the changelog entry.
1598 This information is conveyed via the <tt>Closes</tt> field
1599 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1603 The maintainer name and email address used in the changelog
1604 should be the details of the person uploading <em>this</em>
1605 version. They are <em>not</em> necessarily those of the
1606 usual package maintainer. The information here will be
1607 copied to the <tt>Changed-By</tt> field in the
1608 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1609 and then later used to send an acknowledgement when the
1610 upload has been installed.
1614 The <var>date</var> must be in RFC822 format<footnote>
1615 This is generated by <tt>date -R</tt>.
1616 </footnote>; it must include the time zone specified
1617 numerically, with the time zone name or abbreviation
1618 optionally present as a comment in parentheses.
1622 The first "title" line with the package name must start
1623 at the left hand margin. The "trailer" line with the
1624 maintainer and date details must be preceded by exactly
1625 one space. The maintainer details and the date must be
1626 separated by exactly two spaces.
1630 The entire changelog must be encoded in UTF-8.
1634 For more information on placement of the changelog files
1635 within binary packages, please see <ref id="changelogs">.
1639 <sect id="dpkgcopyright">
1640 <heading>Copyright: <file>debian/copyright</file></heading>
1642 Every package must be accompanied by a verbatim copy of
1643 its copyright and distribution license in the file
1644 <file>/usr/share/doc/<var>package</var>/copyright</file>
1645 (see <ref id="copyrightfile"> for further details). Also see
1646 <ref id="pkgcopyright"> for further considerations relayed
1647 to copyrights for packages.
1651 <heading>Error trapping in makefiles</heading>
1654 When <prgn>make</prgn> invokes a command in a makefile
1655 (including your package's upstream makefiles and
1656 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1657 means that <prgn>sh</prgn>'s usual bad error handling
1658 properties apply: if you include a miniature script as one
1659 of the commands in your makefile you'll find that if you
1660 don't do anything about it then errors are not detected
1661 and <prgn>make</prgn> will blithely continue after
1666 Every time you put more than one shell command (this
1667 includes using a loop) in a makefile command you
1668 must make sure that errors are trapped. For
1669 simple compound commands, such as changing directory and
1670 then running a program, using <tt>&&</tt> rather
1671 than semicolon as a command separator is sufficient. For
1672 more complex commands including most loops and
1673 conditionals you should include a separate <tt>set -e</tt>
1674 command at the start of every makefile command that's
1675 actually one of these miniature shell scripts.
1679 <sect id="timestamps">
1680 <heading>Time Stamps</heading>
1682 Maintainers should preserve the modification times of the
1683 upstream source files in a package, as far as is reasonably
1685 The rationale is that there is some information conveyed
1686 by knowing the age of the file, for example, you could
1687 recognize that some documentation is very old by looking
1688 at the modification time, so it would be nice if the
1689 modification time of the upstream source would be
1695 <sect id="restrictions">
1696 <heading>Restrictions on objects in source packages</heading>
1699 The source package may not contain any hard links<footnote>
1701 This is not currently detected when building source
1702 packages, but only when extracting
1706 Hard links may be permitted at some point in the
1707 future, but would require a fair amount of
1710 </footnote>, device special files, sockets or setuid or
1711 setgid files.<footnote>
1712 Setgid directories are allowed.
1717 <sect id="debianrules">
1718 <heading>Main building script: <file>debian/rules</file></heading>
1721 This file must be an executable makefile, and contains the
1722 package-specific recipes for compiling the package and
1723 building binary package(s) from the source.
1727 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1728 so that it can be invoked by saying its name rather than
1729 invoking <prgn>make</prgn> explicitly.
1733 Since an interactive <file>debian/rules</file> script makes it
1734 impossible to auto-compile that package and also makes it
1735 hard for other people to reproduce the same binary
1736 package, all <em>required targets</em> MUST be
1737 non-interactive. At a minimum, required targets are the
1738 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1739 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1740 <em>binary-indep</em>, and <em>build</em>. It also follows
1741 that any target that these targets depend on must also be
1746 The targets are as follows (required unless stated otherwise):
1748 <tag><tt>build</tt></tag>
1751 The <tt>build</tt> target should perform all the
1752 configuration and compilation of the package.
1753 If a package has an interactive pre-build
1754 configuration routine, the Debianized source package
1755 must either be built after this has taken place (so
1756 that the binary package can be built without rerunning
1757 the configuration) or the configuration routine
1758 modified to become non-interactive. (The latter is
1759 preferable if there are architecture-specific features
1760 detected by the configuration routine.)
1764 For some packages, notably ones where the same
1765 source tree is compiled in different ways to produce
1766 two binary packages, the <tt>build</tt> target
1767 does not make much sense. For these packages it is
1768 good enough to provide two (or more) targets
1769 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1770 for each of the ways of building the package, and a
1771 <tt>build</tt> target that does nothing. The
1772 <tt>binary</tt> target will have to build the
1773 package in each of the possible ways and make the
1774 binary package out of each.
1778 The <tt>build</tt> target must not do anything
1779 that might require root privilege.
1783 The <tt>build</tt> target may need to run the
1784 <tt>clean</tt> target first - see below.
1788 When a package has a configuration and build routine
1789 which takes a long time, or when the makefiles are
1790 poorly designed, or when <tt>build</tt> needs to
1791 run <tt>clean</tt> first, it is a good idea to
1792 <tt>touch build</tt> when the build process is
1793 complete. This will ensure that if <tt>debian/rules
1794 build</tt> is run again it will not rebuild the whole
1796 Another common way to do this is for <tt>build</tt>
1797 to depend on <prgn>build-stamp</prgn> and to do
1798 nothing else, and for the <prgn>build-stamp</prgn>
1799 target to do the building and to <tt>touch
1800 build-stamp</tt> on completion. This is
1801 especially useful if the build routine creates a
1802 file or directory called <tt>build</tt>; in such a
1803 case, <tt>build</tt> will need to be listed as
1804 a phony target (i.e., as a dependency of the
1805 <tt>.PHONY</tt> target). See the documentation of
1806 <prgn>make</prgn> for more information on phony
1812 <tag><tt>build-arch</tt> (optional),
1813 <tt>build-indep</tt> (optional)
1817 A package may also provide both of the targets
1818 <tt>build-arch</tt> and <tt>build-indep</tt>.
1819 The <tt>build-arch</tt> target, if provided, should
1820 perform all the configuration and compilation required
1821 for producing all architecture-dependant binary packages
1822 (those packages for which the body of the
1823 <tt>Architecture</tt> field in <tt>debian/control</tt>
1824 is not <tt>all</tt>).
1825 Similarly, the <tt>build-indep</tt> target, if
1826 provided, should perform all the configuration and
1827 compilation required for producing all
1828 architecture-independent binary packages
1829 (those packages for which the body of the
1830 <tt>Architecture</tt> field in <tt>debian/control</tt>
1832 The <tt>build</tt> target should depend on those of the
1833 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1834 are provided in the rules file.
1838 If one or both of the targets <tt>build-arch</tt> and
1839 <tt>build-indep</tt> are not provided, then invoking
1840 <file>debian/rules</file> with one of the not-provided
1841 targets as arguments should produce a exit status code
1842 of 2. Usually this is provided automatically by make
1843 if the target is missing.
1847 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1848 must not do anything that might require root privilege.
1852 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1853 <tt>binary-indep</tt>
1857 The <tt>binary</tt> target must be all that is
1858 necessary for the user to build the binary package(s)
1859 produced from this source package. It is
1860 split into two parts: <prgn>binary-arch</prgn> builds
1861 the binary packages which are specific to a particular
1862 architecture, and <tt>binary-indep</tt> builds
1863 those which are not.
1866 <tt>binary</tt> may be (and commonly is) a target with
1867 no commands which simply depends on
1868 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1871 Both <tt>binary-*</tt> targets should depend on the
1872 <tt>build</tt> target, or on the appropriate
1873 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1874 provided, so that the package is built if it has not
1875 been already. It should then create the relevant
1876 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1877 make their control files and <prgn>dpkg-deb</prgn> to
1878 build them and place them in the parent of the top
1883 Both the <tt>binary-arch</tt> and
1884 <tt>binary-indep</tt> targets <em>must</em> exist.
1885 If one of them has nothing to do (which will always be
1886 the case if the source generates only a single binary
1887 package, whether architecture-dependent or not), it
1888 must still exist and must always succeed.
1892 The <tt>binary</tt> targets must be invoked as
1894 The <prgn>fakeroot</prgn> package often allows one
1895 to build a package correctly even without being
1901 <tag><tt>clean</tt></tag>
1904 This must undo any effects that the <tt>build</tt>
1905 and <tt>binary</tt> targets may have had, except
1906 that it should leave alone any output files created in
1907 the parent directory by a run of a <tt>binary</tt>
1912 If a <tt>build</tt> file is touched at the end of
1913 the <tt>build</tt> target, as suggested above, it
1914 should be removed as the first action that
1915 <tt>clean</tt> performs, so that running
1916 <tt>build</tt> again after an interrupted
1917 <tt>clean</tt> doesn't think that everything is
1922 The <tt>clean</tt> target may need to be
1923 invoked as root if <tt>binary</tt> has been
1924 invoked since the last <tt>clean</tt>, or if
1925 <tt>build</tt> has been invoked as root (since
1926 <tt>build</tt> may create directories, for
1931 <tag><tt>get-orig-source</tt> (optional)</tag>
1934 This target fetches the most recent version of the
1935 original source package from a canonical archive site
1936 (via FTP or WWW, for example), does any necessary
1937 rearrangement to turn it into the original source
1938 tar file format described below, and leaves it in the
1943 This target may be invoked in any directory, and
1944 should take care to clean up any temporary files it
1949 This target is optional, but providing it if
1950 possible is a good idea.
1954 <tag><tt>patch</tt> (optional)</tag>
1957 This target performs whatever additional actions are
1958 required to make the source ready for editing (unpacking
1959 additional upstream archives, applying patches, etc.).
1960 It is recommended to be implemented for any package where
1961 <tt>dpkg-source -x</tt> does not result in source ready
1962 for additional modification. See
1963 <ref id="readmesource">.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
1999 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2002 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2003 specification string)
2006 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2007 <tt>DEB_*_GNU_TYPE</tt>)
2010 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2011 <tt>DEB_*_GNU_TYPE</tt>)
2013 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2014 the build machine or <tt>HOST</tt> for specification of the
2019 Backward compatibility can be provided in the rules file
2020 by setting the needed variables to suitable default
2021 values; please refer to the documentation of
2022 <prgn>dpkg-architecture</prgn> for details.
2026 It is important to understand that the <tt>DEB_*_ARCH</tt>
2027 string only determines which Debian architecture we are
2028 building on or for. It should not be used to get the CPU
2029 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2030 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2031 GNU style variables should generally only be used with upstream
2035 <sect1 id="debianrules-options">
2036 <heading><file>debian/rules</file> and
2037 <tt>DEB_BUILD_OPTIONS</tt></heading>
2040 Supporting the standardized environment variable
2041 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2042 contain several flags to change how a package is compiled and
2043 built. Each flag must be in the form <var>flag</var> or
2044 <var>flag</var>=<var>options</var>. If multiple flags are
2045 given, they must be separated by whitespace.<footnote>
2046 Some packages support any delimiter, but whitespace is the
2047 easiest to parse inside a makefile and avoids ambiguity with
2048 flag values that contain commas.
2050 <var>flag</var> must start with a lowercase letter
2051 (<tt>a-z</tt>) and consist only of lowercase letters,
2052 numbers (<tt>0-9</tt>), and the characters
2053 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2054 <var>options</var> must not contain whitespace. The same
2055 tag should not be given multiple times with conflicting
2056 values. Package maintainers may assume that
2057 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2061 The meaning of the following tags has been standardized:
2065 This tag says to not run any build-time test suite
2066 provided by the package.
2070 The presence of this tag means that the package should
2071 be compiled with a minimum of optimization. For C
2072 programs, it is best to add <tt>-O0</tt> to
2073 <tt>CFLAGS</tt> (although this is usually the default).
2074 Some programs might fail to build or run at this level
2075 of optimization; it may be necessary to use
2076 <tt>-O1</tt>, for example.
2080 This tag means that the debugging symbols should not be
2081 stripped from the binary during installation, so that
2082 debugging information may be included in the package.
2084 <tag>parallel=n</tag>
2086 This tag means that the package should be built using up
2087 to <tt>n</tt> parallel processes if the package build
2088 system supports this.<footnote>
2089 Packages built with <tt>make</tt> can often implement
2090 this by passing the <tt>-j</tt><var>n</var> option to
2093 If the package build system does not support parallel
2094 builds, this string must be ignored. If the package
2095 build system only supports a lower level of concurrency
2096 than <var>n</var>, the package should be built using as
2097 many parallel processes as the package build system
2098 supports. It is up to the package maintainer to decide
2099 whether the package build times are long enough and the
2100 package build system is robust enough to make supporting
2101 parallel builds worthwhile.
2107 Unknown flags must be ignored by <file>debian/rules</file>.
2111 The following makefile snippet is an example of how one may
2112 implement the build options; you will probably have to
2113 massage this example in order to make it work for your
2115 <example compact="compact">
2118 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2119 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2120 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2121 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2123 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2128 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2129 INSTALL_PROGRAM += -s
2131 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2132 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2133 MAKEFLAGS += -j$(NUMJOBS)
2138 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2139 # Code to run the package test suite.
2146 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2147 <sect id="substvars">
2148 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2151 When <prgn>dpkg-gencontrol</prgn>,
2152 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2153 generate control files they perform variable substitutions
2154 on their output just before writing it. Variable
2155 substitutions have the form <tt>${<var>variable</var>}</tt>.
2156 The optional file <file>debian/substvars</file> contains
2157 variable substitutions to be used; variables can also be set
2158 directly from <file>debian/rules</file> using the <tt>-V</tt>
2159 option to the source packaging commands, and certain
2160 predefined variables are also available.
2164 The <file>debian/substvars</file> file is usually generated and
2165 modified dynamically by <file>debian/rules</file> targets, in
2166 which case it must be removed by the <tt>clean</tt> target.
2170 See <manref name="deb-substvars" section="5"> for full
2171 details about source variable substitutions, including the
2172 format of <file>debian/substvars</file>.</p>
2175 <sect id="debianwatch">
2176 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2179 This is an optional, recommended control file for the
2180 <tt>uscan</tt> utility which defines how to automatically
2181 scan ftp or http sites for newly available updates of the
2182 package. This is used by <url id="
2183 http://dehs.alioth.debian.org/"> and other Debian QA tools
2184 to help with quality control and maintenance of the
2185 distribution as a whole.
2190 <sect id="debianfiles">
2191 <heading>Generated files list: <file>debian/files</file></heading>
2194 This file is not a permanent part of the source tree; it
2195 is used while building packages to record which files are
2196 being generated. <prgn>dpkg-genchanges</prgn> uses it
2197 when it generates a <file>.changes</file> file.
2201 It should not exist in a shipped source package, and so it
2202 (and any backup files or temporary files such as
2203 <file>files.new</file><footnote>
2204 <file>files.new</file> is used as a temporary file by
2205 <prgn>dpkg-gencontrol</prgn> and
2206 <prgn>dpkg-distaddfile</prgn> - they write a new
2207 version of <tt>files</tt> here before renaming it,
2208 to avoid leaving a corrupted copy if an error
2210 </footnote>) should be removed by the
2211 <tt>clean</tt> target. It may also be wise to
2212 ensure a fresh start by emptying or removing it at the
2213 start of the <tt>binary</tt> target.
2217 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2218 package, it adds an entry to <file>debian/files</file> for the
2219 <file>.deb</file> file that will be created when <tt>dpkg-deb
2220 --build</tt> is run for that binary package. So for most
2221 packages all that needs to be done with this file is to
2222 delete it in the <tt>clean</tt> target.
2226 If a package upload includes files besides the source
2227 package and any binary packages whose control files were
2228 made with <prgn>dpkg-gencontrol</prgn> then they should be
2229 placed in the parent of the package's top-level directory
2230 and <prgn>dpkg-distaddfile</prgn> should be called to add
2231 the file to the list in <file>debian/files</file>.</p>
2234 <sect id="embeddedfiles">
2235 <heading>Convenience copies of code</heading>
2238 Some software packages include in their distribution convenience
2239 copies of code from other software packages, generally so that
2240 users compiling from source don't have to download multiple
2241 packages. Debian packages should not make use of these
2242 convenience copies unless the included package is explicitly
2243 intended to be used in this way.<footnote>
2244 For example, parts of the GNU build system work like this.
2246 If the included code is already in the Debian archive in the
2247 form of a library, the Debian packaging should ensure that
2248 binary packages reference the libraries already in Debian and
2249 the convenience copy is not used. If the included code is not
2250 already in Debian, it should be packaged separately as a
2251 prerequisite if possible.
2253 Having multiple copies of the same code in Debian is
2254 inefficient, often creates either static linking or shared
2255 library conflicts, and, most importantly, increases the
2256 difficulty of handling security vulnerabilities in the
2262 <sect id="readmesource">
2263 <heading>Source package handling:
2264 <file>debian/README.source</file></heading>
2267 If running <prgn>dpkg-source -x</prgn> on a source package
2268 doesn't produce the source of the package, ready for editing,
2269 and allow one to make changes and run
2270 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2271 without taking any additional steps, creating a
2272 <file>debian/README.source</file> documentation file is
2273 recommended. This file should explain how to do all of the
2276 <item>Generate the fully patched source, in a form ready for
2277 editing, that would be built to create Debian
2278 packages. Doing this with a <tt>patch</tt> target in
2279 <file>debian/rules</file> is recommended; see
2280 <ref id="debianrules">.</item>
2281 <item>Modify the source and save those modifications so that
2282 they will be applied when building the package.</item>
2283 <item>Remove source modifications that are currently being
2284 applied when building the package.</item>
2285 <item>Optionally, document what steps are necessary to
2286 upgrade the Debian source package to a new upstream version,
2287 if applicable.</item>
2289 This explanation should include specific commands and mention
2290 any additional required Debian packages. It should not assume
2291 familiarity with any specific Debian packaging system or patch
2296 This explanation may refer to a documentation file installed by
2297 one of the package's build dependencies provided that the
2298 referenced documentation clearly explains these tasks and is not
2299 a general reference manual.
2303 <file>debian/README.source</file> may also include any other
2304 information that would be helpful to someone modifying the
2305 source package. Even if the package doesn't fit the above
2306 description, maintainers are encouraged to document in a
2307 <file>debian/README.source</file> file any source package with a
2308 particularly complex or unintuitive source layout or build
2309 system (for example, a package that builds the same source
2310 multiple times to generate different binary packages).
2316 <chapt id="controlfields">
2317 <heading>Control files and their fields</heading>
2320 The package management system manipulates data represented in
2321 a common format, known as <em>control data</em>, stored in
2322 <em>control files</em>.
2323 Control files are used for source packages, binary packages and
2324 the <file>.changes</file> files which control the installation
2325 of uploaded files<footnote>
2326 <prgn>dpkg</prgn>'s internal databases are in a similar
2331 <sect id="controlsyntax">
2332 <heading>Syntax of control files</heading>
2335 A control file consists of one or more paragraphs of
2337 The paragraphs are also sometimes referred to as stanzas.
2339 The paragraphs are separated by blank lines. Some control
2340 files allow only one paragraph; others allow several, in
2341 which case each paragraph usually refers to a different
2342 package. (For example, in source packages, the first
2343 paragraph refers to the source package, and later paragraphs
2344 refer to binary packages generated from the source.)
2348 Each paragraph consists of a series of data fields; each
2349 field consists of the field name, followed by a colon and
2350 then the data/value associated with that field. It ends at
2351 the end of the (logical) line. Horizontal whitespace
2352 (spaces and tabs) may occur immediately before or after the
2353 value and is ignored there; it is conventional to put a
2354 single space after the colon. For example, a field might
2356 <example compact="compact">
2359 the field name is <tt>Package</tt> and the field value
2364 Many fields' values may span several lines; in this case
2365 each continuation line must start with a space or a tab.
2366 Any trailing spaces or tabs at the end of individual
2367 lines of a field value are ignored.
2371 In fields where it is specified that lines may not wrap,
2372 only a single line of data is allowed and whitespace is not
2373 significant in a field body. Whitespace must not appear
2374 inside names (of packages, architectures, files or anything
2375 else) or version numbers, or between the characters of
2376 multi-character version relationships.
2380 Field names are not case-sensitive, but it is usual to
2381 capitalize the field names using mixed case as shown below.
2385 Blank lines, or lines consisting only of spaces and tabs,
2386 are not allowed within field values or between fields - that
2387 would mean a new paragraph.
2391 All control files must be encoded in UTF-8.
2395 <sect id="sourcecontrolfiles">
2396 <heading>Source package control files -- <file>debian/control</file></heading>
2399 The <file>debian/control</file> file contains the most vital
2400 (and version-independent) information about the source package
2401 and about the binary packages it creates.
2405 The first paragraph of the control file contains information about
2406 the source package in general. The subsequent sets each describe a
2407 binary package that the source tree builds.
2411 The fields in the general paragraph (the first one, for the source
2414 <list compact="compact">
2415 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2416 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2417 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2418 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2419 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2420 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2421 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2422 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2427 The fields in the binary package paragraphs are:
2429 <list compact="compact">
2430 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2431 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2432 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2433 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2434 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2435 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2436 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2437 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2442 The syntax and semantics of the fields are described below.
2448 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2449 generate control files for binary packages (see below), by
2450 <prgn>dpkg-genchanges</prgn> to generate the
2451 <tt>.changes</tt> file to accompany the upload, and by
2452 <prgn>dpkg-source</prgn> when it creates the
2453 <file>.dsc</file> source control file as part of a source
2454 archive. Many fields are permitted to span multiple lines in
2455 <file>debian/control</file> but not in any other control
2456 file. These tools are responsible for removing the line
2457 breaks from such fields when using fields from
2458 <file>debian/control</file> to generate other control files.
2462 The fields here may contain variable references - their
2463 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2464 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2465 when they generate output control files.
2466 See <ref id="substvars"> for details.
2470 In addition to the control file syntax described <qref
2471 id="controlsyntax">above</qref>, this file may also contain
2472 comment lines starting with <tt>#</tt> without any preceding
2473 whitespace. All such lines are ignored, even in the middle of
2474 continuation lines for a multiline field, and do not end a
2480 <sect id="binarycontrolfiles">
2481 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2484 The <file>DEBIAN/control</file> file contains the most vital
2485 (and version-dependent) information about a binary package.
2489 The fields in this file are:
2491 <list compact="compact">
2492 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2493 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2494 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2495 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2496 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2497 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2498 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2499 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2500 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2501 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2502 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2503 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2508 <sect id="debiansourcecontrolfiles">
2509 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2512 This file contains a series of fields, identified and
2513 separated just like the fields in the control file of
2514 a binary package. The fields are listed below; their
2515 syntax is described above, in <ref id="pkg-controlfields">.
2517 <list compact="compact">
2518 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2519 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2520 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2522 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2523 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2524 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2525 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2526 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2527 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2528 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2533 The source package control file is generated by
2534 <prgn>dpkg-source</prgn> when it builds the source
2535 archive, from other files in the source package,
2536 described above. When unpacking, it is checked against
2537 the files and directories in the other parts of the
2543 <sect id="debianchangesfiles">
2544 <heading>Debian changes files -- <file>.changes</file></heading>
2547 The .changes files are used by the Debian archive maintenance
2548 software to process updates to packages. They contain one
2549 paragraph which contains information from the
2550 <tt>debian/control</tt> file and other data about the
2551 source package gathered via <tt>debian/changelog</tt>
2552 and <tt>debian/rules</tt>.
2556 The fields in this file are:
2558 <list compact="compact">
2559 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2560 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2561 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2562 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2563 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2564 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2567 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2569 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2570 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2571 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2577 <sect id="controlfieldslist">
2578 <heading>List of fields</heading>
2580 <sect1 id="f-Source">
2581 <heading><tt>Source</tt></heading>
2584 This field identifies the source package name.
2588 In <file>debian/control</file> or a <file>.dsc</file> file,
2589 this field must contain only the name of the source package.
2593 In a binary package control file or a <file>.changes</file>
2594 file, the source package name may be followed by a version
2595 number in parentheses<footnote>
2596 It is customary to leave a space after the package name
2597 if a version number is specified.
2599 This version number may be omitted (and is, by
2600 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2601 the <tt>Version</tt> field of the binary package in
2602 question. The field itself may be omitted from a binary
2603 package control file when the source package has the same
2604 name and version as the binary package.
2608 Package names (both source and binary,
2609 see <ref id="f-Package">) must consist only of lower case
2610 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2611 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2612 (<tt>.</tt>). They must be at least two characters long and
2613 must start with an alphanumeric character.
2617 <sect1 id="f-Maintainer">
2618 <heading><tt>Maintainer</tt></heading>
2621 The package maintainer's name and email address. The name
2622 should come first, then the email address inside angle
2623 brackets <tt><></tt> (in RFC822 format).
2627 If the maintainer's name contains a full stop then the
2628 whole field will not work directly as an email address due
2629 to a misfeature in the syntax specified in RFC822; a
2630 program using this field as an address must check for this
2631 and correct the problem if necessary (for example by
2632 putting the name in round brackets and moving it to the
2633 end, and bringing the email address forward).
2637 <sect1 id="f-Uploaders">
2638 <heading><tt>Uploaders</tt></heading>
2641 List of the names and email addresses of co-maintainers of
2642 the package, if any. If the package has other maintainers
2643 beside the one named in the
2644 <qref id="f-Maintainer">Maintainer field</qref>, their
2645 names and email addresses should be listed here. The
2646 format is the same as that of the Maintainer tag, and
2647 multiple entries should be comma separated. Currently,
2648 this field is restricted to a single line of data. This
2649 is an optional field.
2652 Any parser that interprets the Uploaders field in
2653 <file>debian/control</file> must permit it to span multiple
2654 lines. Line breaks in an Uploaders field that spans multiple
2655 lines are not significant and the semantics of the field are
2656 the same as if the line breaks had not been present.
2660 <sect1 id="f-Changed-By">
2661 <heading><tt>Changed-By</tt></heading>
2664 The name and email address of the person who changed the
2665 said package. Usually the name of the maintainer.
2666 All the rules for the Maintainer field apply here, too.
2670 <sect1 id="f-Section">
2671 <heading><tt>Section</tt></heading>
2674 This field specifies an application area into which the package
2675 has been classified. See <ref id="subsections">.
2679 When it appears in the <file>debian/control</file> file,
2680 it gives the value for the subfield of the same name in
2681 the <tt>Files</tt> field of the <file>.changes</file> file.
2682 It also gives the default for the same field in the binary
2687 <sect1 id="f-Priority">
2688 <heading><tt>Priority</tt></heading>
2691 This field represents how important that it is that the user
2692 have the package installed. See <ref id="priorities">.
2696 When it appears in the <file>debian/control</file> file,
2697 it gives the value for the subfield of the same name in
2698 the <tt>Files</tt> field of the <file>.changes</file> file.
2699 It also gives the default for the same field in the binary
2704 <sect1 id="f-Package">
2705 <heading><tt>Package</tt></heading>
2708 The name of the binary package.
2712 Binary package names must follow the same syntax and
2713 restrictions as source package names. See <ref id="f-Source">
2718 <sect1 id="f-Architecture">
2719 <heading><tt>Architecture</tt></heading>
2722 Depending on context and the control file used, the
2723 <tt>Architecture</tt> field can include the following sets of
2726 <item>A unique single word identifying a Debian machine
2727 architecture as described in <ref id="arch-spec">.
2728 <item><tt>all</tt>, which indicates an
2729 architecture-independent package.
2730 <item><tt>any</tt>, which indicates a package available
2731 for building on any architecture.
2732 <item><tt>source</tt>, which indicates a source package.
2737 In the main <file>debian/control</file> file in the source
2738 package, this field may contain the special value
2739 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2740 architectures separated by spaces. If <tt>any</tt> or
2741 <tt>all</tt> appear, they must be the entire contents of the
2742 field. Most packages will use either <tt>any</tt> or
2743 <tt>all</tt>. Specifying a specific list of architectures is
2744 for the minority of cases where a program is not portable or
2745 is not useful on some architectures, and where possible the
2746 program should be made portable instead.
2750 In the source package control file <file>.dsc</file>, this
2751 field may contain either the special value <tt>any</tt> or a
2752 list of architectures separated by spaces. If a list is given,
2753 it may include (or consist solely of) the special value
2754 <tt>all</tt>. In other words, in <file>.dsc</file> files
2755 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2756 in combination with specific architectures. The
2757 <tt>Architecture</tt> field in the source package control file
2758 <file>.dsc</file> is generally constructed from the
2759 <tt>Architecture</tt> fields in the
2760 <file>debian/control</file> in the source package.
2764 Specifying <tt>any</tt> indicates that the source package
2765 isn't dependent on any particular architecture and should
2766 compile fine on any one. The produced binary package(s)
2767 will either be specific to whatever the current build
2768 architecture is or will be architecture-independent.
2772 Specifying only <tt>all</tt> indicates that the source package
2773 will only build architecture-independent packages. If this is
2774 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2775 <tt>any</tt> implies that the source package will build at
2776 least one architecture-dependent package.
2780 Specifying a list of architectures indicates that the source
2781 will build an architecture-dependent package, and will only
2782 work correctly on the listed architectures. If the source
2783 package also builds at least one architecture-independent
2784 package, <tt>all</tt> will also be included in the list.
2788 In a <file>.changes</file> file, the <tt>Architecture</tt>
2789 field lists the architecture(s) of the package(s)
2790 currently being uploaded. This will be a list; if the
2791 source for the package is also being uploaded, the special
2792 entry <tt>source</tt> is also present. <tt>all</tt> will be
2793 present if any architecture-independent packages are being
2794 uploaded. <tt>any</tt> may never occur in the
2795 <tt>Architecture</tt> field in the <file>.changes</file>
2800 See <ref id="debianrules"> for information how to get the
2801 architecture for the build process.
2805 <sect1 id="f-Essential">
2806 <heading><tt>Essential</tt></heading>
2809 This is a boolean field which may occur only in the
2810 control file of a binary package or in a per-package fields
2811 paragraph of a main source control data file.
2815 If set to <tt>yes</tt> then the package management system
2816 will refuse to remove the package (upgrading and replacing
2817 it is still possible). The other possible value is <tt>no</tt>,
2818 which is the same as not having the field at all.
2823 <heading>Package interrelationship fields:
2824 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2825 <tt>Recommends</tt>, <tt>Suggests</tt>,
2826 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2827 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2831 These fields describe the package's relationships with
2832 other packages. Their syntax and semantics are described
2833 in <ref id="relationships">.</p>
2836 <sect1 id="f-Standards-Version">
2837 <heading><tt>Standards-Version</tt></heading>
2840 The most recent version of the standards (the policy
2841 manual and associated texts) with which the package
2846 The version number has four components: major and minor
2847 version number and major and minor patch level. When the
2848 standards change in a way that requires every package to
2849 change the major number will be changed. Significant
2850 changes that will require work in many packages will be
2851 signaled by a change to the minor number. The major patch
2852 level will be changed for any change to the meaning of the
2853 standards, however small; the minor patch level will be
2854 changed when only cosmetic, typographical or other edits
2855 are made which neither change the meaning of the document
2856 nor affect the contents of packages.
2860 Thus only the first three components of the policy version
2861 are significant in the <em>Standards-Version</em> control
2862 field, and so either these three components or the all
2863 four components may be specified.<footnote>
2864 In the past, people specified the full version number
2865 in the Standards-Version field, for example "2.3.0.0".
2866 Since minor patch-level changes don't introduce new
2867 policy, it was thought it would be better to relax
2868 policy and only require the first 3 components to be
2869 specified, in this example "2.3.0". All four
2870 components may still be used if someone wishes to do so.
2876 <sect1 id="f-Version">
2877 <heading><tt>Version</tt></heading>
2880 The version number of a package. The format is:
2881 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2885 The three components here are:
2887 <tag><var>epoch</var></tag>
2890 This is a single (generally small) unsigned integer. It
2891 may be omitted, in which case zero is assumed. If it is
2892 omitted then the <var>upstream_version</var> may not
2897 It is provided to allow mistakes in the version numbers
2898 of older versions of a package, and also a package's
2899 previous version numbering schemes, to be left behind.
2903 <tag><var>upstream_version</var></tag>
2906 This is the main part of the version number. It is
2907 usually the version number of the original ("upstream")
2908 package from which the <file>.deb</file> file has been made,
2909 if this is applicable. Usually this will be in the same
2910 format as that specified by the upstream author(s);
2911 however, it may need to be reformatted to fit into the
2912 package management system's format and comparison
2917 The comparison behavior of the package management system
2918 with respect to the <var>upstream_version</var> is
2919 described below. The <var>upstream_version</var>
2920 portion of the version number is mandatory.
2924 The <var>upstream_version</var> may contain only
2925 alphanumerics<footnote>
2926 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2928 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2929 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2930 tilde) and should start with a digit. If there is no
2931 <var>debian_revision</var> then hyphens are not allowed;
2932 if there is no <var>epoch</var> then colons are not
2937 <tag><var>debian_revision</var></tag>
2940 This part of the version number specifies the version of
2941 the Debian package based on the upstream version. It
2942 may contain only alphanumerics and the characters
2943 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2944 tilde) and is compared in the same way as the
2945 <var>upstream_version</var> is.
2949 It is optional; if it isn't present then the
2950 <var>upstream_version</var> may not contain a hyphen.
2951 This format represents the case where a piece of
2952 software was written specifically to be turned into a
2953 Debian package, and so there is only one "debianisation"
2954 of it and therefore no revision indication is required.
2958 It is conventional to restart the
2959 <var>debian_revision</var> at <tt>1</tt> each time the
2960 <var>upstream_version</var> is increased.
2964 The package management system will break the version
2965 number apart at the last hyphen in the string (if there
2966 is one) to determine the <var>upstream_version</var> and
2967 <var>debian_revision</var>. The absence of a
2968 <var>debian_revision</var> is equivalent to a
2969 <var>debian_revision</var> of <tt>0</tt>.
2976 When comparing two version numbers, first the <var>epoch</var>
2977 of each are compared, then the <var>upstream_version</var> if
2978 <var>epoch</var> is equal, and then <var>debian_revision</var>
2979 if <var>upstream_version</var> is also equal.
2980 <var>epoch</var> is compared numerically. The
2981 <var>upstream_version</var> and <var>debian_revision</var>
2982 parts are compared by the package management system using the
2983 following algorithm:
2987 The strings are compared from left to right.
2991 First the initial part of each string consisting entirely of
2992 non-digit characters is determined. These two parts (one of
2993 which may be empty) are compared lexically. If a difference
2994 is found it is returned. The lexical comparison is a
2995 comparison of ASCII values modified so that all the letters
2996 sort earlier than all the non-letters and so that a tilde
2997 sorts before anything, even the end of a part. For example,
2998 the following parts are in sorted order from earliest to
2999 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3000 <tt>a</tt>.<footnote>
3001 One common use of <tt>~</tt> is for upstream pre-releases.
3002 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3003 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3008 Then the initial part of the remainder of each string which
3009 consists entirely of digit characters is determined. The
3010 numerical values of these two parts are compared, and any
3011 difference found is returned as the result of the comparison.
3012 For these purposes an empty string (which can only occur at
3013 the end of one or both version strings being compared) counts
3018 These two steps (comparing and removing initial non-digit
3019 strings and initial digit strings) are repeated until a
3020 difference is found or both strings are exhausted.
3024 Note that the purpose of epochs is to allow us to leave behind
3025 mistakes in version numbering, and to cope with situations
3026 where the version numbering scheme changes. It is
3027 <em>not</em> intended to cope with version numbers containing
3028 strings of letters which the package management system cannot
3029 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3030 silly orderings (the author of this manual has heard of a
3031 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3032 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3033 <tt>2</tt> and so forth).
3037 <sect1 id="f-Description">
3038 <heading><tt>Description</tt></heading>
3041 In a source or binary control file, the <tt>Description</tt>
3042 field contains a description of the binary package, consisting
3043 of two parts, the synopsis or the short description, and the
3044 long description. The field's format is as follows:
3049 Description: <single line synopsis>
3050 <extended description over several lines>
3055 The lines in the extended description can have these formats:
3061 Those starting with a single space are part of a paragraph.
3062 Successive lines of this form will be word-wrapped when
3063 displayed. The leading space will usually be stripped off.
3067 Those starting with two or more spaces. These will be
3068 displayed verbatim. If the display cannot be panned
3069 horizontally, the displaying program will line wrap them "hard"
3070 (i.e., without taking account of word breaks). If it can they
3071 will be allowed to trail off to the right. None, one or two
3072 initial spaces may be deleted, but the number of spaces
3073 deleted from each line will be the same (so that you can have
3074 indenting work correctly, for example).
3078 Those containing a single space followed by a single full stop
3079 character. These are rendered as blank lines. This is the
3080 <em>only</em> way to get a blank line<footnote>
3081 Completely empty lines will not be rendered as blank lines.
3082 Instead, they will cause the parser to think you're starting
3083 a whole new record in the control file, and will therefore
3084 likely abort with an error.
3089 Those containing a space, a full stop and some more characters.
3090 These are for future expansion. Do not use them.
3096 Do not use tab characters. Their effect is not predictable.
3100 See <ref id="descriptions"> for further information on this.
3104 In a <file>.changes</file> file, the <tt>Description</tt>
3105 field contains a summary of the descriptions for the packages
3106 being uploaded. For this case, the first line of the field
3107 value (the part on the same line as <tt>Description:</tt>) is
3108 always empty. The content of the field is expressed as
3109 continuation lines, one line per package. Each line is
3110 indented by one space and contains the name of a binary
3111 package, a space, a hyphen (<tt>-</tt>), a space, and the
3112 short description line from that package.
3116 <sect1 id="f-Distribution">
3117 <heading><tt>Distribution</tt></heading>
3120 In a <file>.changes</file> file or parsed changelog output
3121 this contains the (space-separated) name(s) of the
3122 distribution(s) where this version of the package should
3123 be installed. Valid distributions are determined by the
3124 archive maintainers.<footnote>
3125 Example distribution names in the Debian archive used in
3126 <file>.changes</file> files are:
3127 <taglist compact="compact">
3128 <tag><em>unstable</em></tag>
3130 This distribution value refers to the
3131 <em>developmental</em> part of the Debian distribution
3132 tree. Most new packages, new upstream versions of
3133 packages and bug fixes go into the <em>unstable</em>
3137 <tag><em>experimental</em></tag>
3139 The packages with this distribution value are deemed
3140 by their maintainers to be high risk. Oftentimes they
3141 represent early beta or developmental packages from
3142 various sources that the maintainers want people to
3143 try, but are not ready to be a part of the other parts
3144 of the Debian distribution tree.
3149 Others are used for updating stable releases or for
3150 security uploads. More information is available in the
3151 Debian Developer's Reference, section "The Debian
3155 The Debian archive software only supports listing a single
3156 distribution. Migration of packages to other distributions is
3157 handled outside of the upload process.
3162 <heading><tt>Date</tt></heading>
3165 This field includes the date the package was built or last edited.
3169 The value of this field is usually extracted from the
3170 <file>debian/changelog</file> file - see
3171 <ref id="dpkgchangelog">).
3175 <sect1 id="f-Format">
3176 <heading><tt>Format</tt></heading>
3179 This field specifies a format revision for the file.
3180 The most current format described in the Policy Manual
3181 is version <strong>1.5</strong>. The syntax of the
3182 format value is the same as that of a package version
3183 number except that no epoch or Debian revision is allowed
3184 - see <ref id="f-Version">.
3188 <sect1 id="f-Urgency">
3189 <heading><tt>Urgency</tt></heading>
3192 This is a description of how important it is to upgrade to
3193 this version from previous ones. It consists of a single
3194 keyword taking one of the values <tt>low</tt>,
3195 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3196 <tt>critical</tt><footnote>
3197 Other urgency values are supported with configuration
3198 changes in the archive software but are not used in Debian.
3199 The urgency affects how quickly a package will be considered
3200 for inclusion into the <tt>testing</tt> distribution and
3201 gives an indication of the importance of any fixes included
3202 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3203 treated as synonymous.
3204 </footnote> (not case-sensitive) followed by an optional
3205 commentary (separated by a space) which is usually in
3206 parentheses. For example:
3209 Urgency: low (HIGH for users of diversions)
3215 The value of this field is usually extracted from the
3216 <file>debian/changelog</file> file - see
3217 <ref id="dpkgchangelog">.
3221 <sect1 id="f-Changes">
3222 <heading><tt>Changes</tt></heading>
3225 This field contains the human-readable changes data, describing
3226 the differences between the last version and the current one.
3230 The first line of the field value (the part on the same line
3231 as <tt>Changes:</tt>) is always empty. The content of the
3232 field is expressed as continuation lines, with each line
3233 indented by at least one space. Blank lines must be
3234 represented by a line consisting only of a space and a full
3239 The value of this field is usually extracted from the
3240 <file>debian/changelog</file> file - see
3241 <ref id="dpkgchangelog">).
3245 Each version's change information should be preceded by a
3246 "title" line giving at least the version, distribution(s)
3247 and urgency, in a human-readable way.
3251 If data from several versions is being returned the entry
3252 for the most recent version should be returned first, and
3253 entries should be separated by the representation of a
3254 blank line (the "title" line may also be followed by the
3255 representation of blank line).
3259 <sect1 id="f-Binary">
3260 <heading><tt>Binary</tt></heading>
3263 This field is a list of binary packages. Its syntax and
3264 meaning varies depending on the control file in which it
3269 When it appears in the <file>.dsc</file> file, it lists binary
3270 packages which a source package can produce, separated by
3272 A space after each comma is conventional.
3273 </footnote>. It may span multiple lines. The source package
3274 does not necessarily produce all of these binary packages for
3275 every architecture. The source control file doesn't contain
3276 details of which architectures are appropriate for which of
3277 the binary packages.
3281 When it appears in a <file>.changes</file> file, it lists the
3282 names of the binary packages being uploaded, separated by
3283 whitespace (not commas). It may span multiple lines.
3287 <sect1 id="f-Installed-Size">
3288 <heading><tt>Installed-Size</tt></heading>
3291 This field appears in the control files of binary packages,
3292 and in the <file>Packages</file> files. It gives an estimate
3293 of the total amount of disk space required to install the
3294 named package. Actual installed size may vary based on block
3295 size, file system properties, or actions taken by package
3300 The disk space is given as the integer value of the estimated
3301 installed size in bytes, divided by 1024 and rounded up.
3305 <sect1 id="f-Files">
3306 <heading><tt>Files</tt></heading>
3309 This field contains a list of files with information about
3310 each one. The exact information and syntax varies with
3315 In all cases, Files is a multiline field. The first line of
3316 the field value (the part on the same line as <tt>Files:</tt>)
3317 is always empty. The content of the field is expressed as
3318 continuation lines, one line per file. Each line must be
3319 indented by one space and contain a number of sub-fields,
3320 separated by spaces, as described below.
3324 In the <file>.dsc</file> file, each line contains the MD5
3325 checksum, size and filename of the tar file and (if
3326 applicable) diff file which make up the remainder of the
3327 source package<footnote>
3328 That is, the parts which are not the <tt>.dsc</tt>.
3329 </footnote>. For example:
3332 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3333 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3335 The exact forms of the filenames are described
3336 in <ref id="pkg-sourcearchives">.
3340 In the <file>.changes</file> file this contains one line per
3341 file being uploaded. Each line contains the MD5 checksum,
3342 size, section and priority and the filename. For example:
3345 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3346 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3347 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3348 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3350 The <qref id="f-Section">section</qref>
3351 and <qref id="f-Priority">priority</qref> are the values of
3352 the corresponding fields in the main source control file. If
3353 no section or priority is specified then <tt>-</tt> should be
3354 used, though section and priority values must be specified for
3355 new packages to be installed properly.
3359 The special value <tt>byhand</tt> for the section in a
3360 <tt>.changes</tt> file indicates that the file in question
3361 is not an ordinary package file and must by installed by
3362 hand by the distribution maintainers. If the section is
3363 <tt>byhand</tt> the priority should be <tt>-</tt>.
3367 If a new Debian revision of a package is being shipped and
3368 no new original source archive is being distributed the
3369 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3370 entry for the original source archive
3371 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3372 but the <file>.changes</file> file should leave it out. In
3373 this case the original source archive on the distribution
3374 site must match exactly, byte-for-byte, the original
3375 source archive which was used to generate the
3376 <file>.dsc</file> file and diff which are being uploaded.</p>
3379 <sect1 id="f-Closes">
3380 <heading><tt>Closes</tt></heading>
3383 A space-separated list of bug report numbers that the upload
3384 governed by the .changes file closes.
3388 <sect1 id="f-Homepage">
3389 <heading><tt>Homepage</tt></heading>
3392 The URL of the web site for this package, preferably (when
3393 applicable) the site from which the original source can be
3394 obtained and any additional upstream documentation or
3395 information may be found. The content of this field is a
3396 simple URL without any surrounding characters such as
3404 <heading>User-defined fields</heading>
3407 Additional user-defined fields may be added to the
3408 source package control file. Such fields will be
3409 ignored, and not copied to (for example) binary or
3410 source package control files or upload control files.
3414 If you wish to add additional unsupported fields to
3415 these output files you should use the mechanism
3420 Fields in the main source control information file with
3421 names starting <tt>X</tt>, followed by one or more of
3422 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3423 be copied to the output files. Only the part of the
3424 field name after the hyphen will be used in the output
3425 file. Where the letter <tt>B</tt> is used the field
3426 will appear in binary package control files, where the
3427 letter <tt>S</tt> is used in source package control
3428 files and where <tt>C</tt> is used in upload control
3429 (<tt>.changes</tt>) files.
3433 For example, if the main source information control file
3436 XBS-Comment: I stand between the candle and the star.
3438 then the binary and source package control files will contain the
3441 Comment: I stand between the candle and the star.
3450 <chapt id="maintainerscripts">
3451 <heading>Package maintainer scripts and installation procedure</heading>
3454 <heading>Introduction to package maintainer scripts</heading>
3457 It is possible to supply scripts as part of a package which
3458 the package management system will run for you when your
3459 package is installed, upgraded or removed.
3463 These scripts are the files <prgn>preinst</prgn>,
3464 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3465 <prgn>postrm</prgn> in the control area of the package.
3466 They must be proper executable files; if they are scripts
3467 (which is recommended), they must start with the usual
3468 <tt>#!</tt> convention. They should be readable and
3469 executable by anyone, and must not be world-writable.
3473 The package management system looks at the exit status from
3474 these scripts. It is important that they exit with a
3475 non-zero status if there is an error, so that the package
3476 management system can stop its processing. For shell
3477 scripts this means that you <em>almost always</em> need to
3478 use <tt>set -e</tt> (this is usually true when writing shell
3479 scripts, in fact). It is also important, of course, that
3480 they exit with a zero status if everything went well.
3484 Additionally, packages interacting with users using
3485 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3486 install a <prgn>config</prgn> script in the control area,
3487 see <ref id="maintscriptprompt"> for details.
3491 When a package is upgraded a combination of the scripts from
3492 the old and new packages is called during the upgrade
3493 procedure. If your scripts are going to be at all
3494 complicated you need to be aware of this, and may need to
3495 check the arguments to your scripts.
3499 Broadly speaking the <prgn>preinst</prgn> is called before
3500 (a particular version of) a package is installed, and the
3501 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3502 before (a version of) a package is removed and the
3503 <prgn>postrm</prgn> afterwards.
3507 Programs called from maintainer scripts should not normally
3508 have a path prepended to them. Before installation is
3509 started, the package management system checks to see if the
3510 programs <prgn>ldconfig</prgn>,
3511 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3512 and <prgn>update-rc.d</prgn> can be found via the
3513 <tt>PATH</tt> environment variable. Those programs, and any
3514 other program that one would expect to be in the
3515 <tt>PATH</tt>, should thus be invoked without an absolute
3516 pathname. Maintainer scripts should also not reset the
3517 <tt>PATH</tt>, though they might choose to modify it by
3518 prepending or appending package-specific directories. These
3519 considerations really apply to all shell scripts.</p>
3522 <sect id="idempotency">
3523 <heading>Maintainer scripts idempotency</heading>
3526 It is necessary for the error recovery procedures that the
3527 scripts be idempotent. This means that if it is run
3528 successfully, and then it is called again, it doesn't bomb
3529 out or cause any harm, but just ensures that everything is
3530 the way it ought to be. If the first call failed, or
3531 aborted half way through for some reason, the second call
3532 should merely do the things that were left undone the first
3533 time, if any, and exit with a success status if everything
3535 This is so that if an error occurs, the user interrupts
3536 <prgn>dpkg</prgn> or some other unforeseen circumstance
3537 happens you don't leave the user with a badly-broken
3538 package when <prgn>dpkg</prgn> attempts to repeat the
3544 <sect id="controllingterminal">
3545 <heading>Controlling terminal for maintainer scripts</heading>
3548 The maintainer scripts are guaranteed to run with a
3549 controlling terminal and can interact with the user.
3550 Because these scripts may be executed with standard output
3551 redirected into a pipe for logging purposes, Perl scripts
3552 should set unbuffered output by setting <tt>$|=1</tt> so
3553 that the output is printed immediately rather than being
3557 <sect id="exitstatus">
3558 <heading>Exit status</heading>
3561 Each script must return a zero exit status for
3562 success, or a nonzero one for failure, since the package
3563 management system looks for the exit status of these scripts
3564 and determines what action to take next based on that datum.
3568 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3573 <list compact="compact">
3575 <var>new-preinst</var> <tt>install</tt>
3578 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3581 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3584 <var>old-preinst</var> <tt>abort-upgrade</tt>
3585 <var>new-version</var>
3590 <list compact="compact">
3592 <var>postinst</var> <tt>configure</tt>
3593 <var>most-recently-configured-version</var>
3596 <var>old-postinst</var> <tt>abort-upgrade</tt>
3597 <var>new-version</var>
3600 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3601 <tt>in-favour</tt> <var>package</var>
3602 <var>new-version</var>
3605 <var>postinst</var> <tt>abort-remove</tt>
3608 <var>deconfigured's-postinst</var>
3609 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3610 <var>failed-install-package</var> <var>version</var>
3611 [<tt>removing</tt> <var>conflicting-package</var>
3617 <list compact="compact">
3619 <var>prerm</var> <tt>remove</tt>
3622 <var>old-prerm</var> <tt>upgrade</tt>
3623 <var>new-version</var>
3626 <var>new-prerm</var> <tt>failed-upgrade</tt>
3627 <var>old-version</var>
3630 <var>conflictor's-prerm</var> <tt>remove</tt>
3631 <tt>in-favour</tt> <var>package</var>
3632 <var>new-version</var>
3635 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3636 <tt>in-favour</tt> <var>package-being-installed</var>
3637 <var>version</var> [<tt>removing</tt>
3638 <var>conflicting-package</var>
3644 <list compact="compact">
3646 <var>postrm</var> <tt>remove</tt>
3649 <var>postrm</var> <tt>purge</tt>
3652 <var>old-postrm</var> <tt>upgrade</tt>
3653 <var>new-version</var>
3656 <var>new-postrm</var> <tt>failed-upgrade</tt>
3657 <var>old-version</var>
3660 <var>new-postrm</var> <tt>abort-install</tt>
3663 <var>new-postrm</var> <tt>abort-install</tt>
3664 <var>old-version</var>
3667 <var>new-postrm</var> <tt>abort-upgrade</tt>
3668 <var>old-version</var>
3671 <var>disappearer's-postrm</var> <tt>disappear</tt>
3672 <var>overwriter</var>
3673 <var>overwriter-version</var>
3679 <sect id="unpackphase">
3680 <heading>Details of unpack phase of installation or upgrade</heading>
3683 The procedure on installation/upgrade/overwrite/disappear
3684 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3685 stage of <tt>dpkg --install</tt>) is as follows. In each
3686 case, if a major error occurs (unless listed below) the
3687 actions are, in general, run backwards - this means that the
3688 maintainer scripts are run with different arguments in
3689 reverse order. These are the "error unwind" calls listed
3696 If a version of the package is already installed, call
3697 <example compact="compact">
3698 <var>old-prerm</var> upgrade <var>new-version</var>
3702 If the script runs but exits with a non-zero
3703 exit status, <prgn>dpkg</prgn> will attempt:
3704 <example compact="compact">
3705 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3707 If this works, the upgrade continues. If this
3708 does not work, the error unwind:
3709 <example compact="compact">
3710 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3712 If this works, then the old-version is
3713 "Installed", if not, the old version is in a
3714 "Failed-Config" state.
3720 If a "conflicting" package is being removed at the same time,
3721 or if any package will be broken (due to <tt>Breaks</tt>):
3724 If <tt>--auto-deconfigure</tt> is
3725 specified, call, for each package to be deconfigured
3726 due to <tt>Breaks</tt>:
3727 <example compact="compact">
3728 <var>deconfigured's-prerm</var> deconfigure \
3729 in-favour <var>package-being-installed</var> <var>version</var>
3732 <example compact="compact">
3733 <var>deconfigured's-postinst</var> abort-deconfigure \
3734 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3736 The deconfigured packages are marked as
3737 requiring configuration, so that if
3738 <tt>--install</tt> is used they will be
3739 configured again if possible.
3742 If any packages depended on a conflicting
3743 package being removed and <tt>--auto-deconfigure</tt> is
3744 specified, call, for each such package:
3745 <example compact="compact">
3746 <var>deconfigured's-prerm</var> deconfigure \
3747 in-favour <var>package-being-installed</var> <var>version</var> \
3748 removing <var>conflicting-package</var> <var>version</var>
3751 <example compact="compact">
3752 <var>deconfigured's-postinst</var> abort-deconfigure \
3753 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3754 removing <var>conflicting-package</var> <var>version</var>
3756 The deconfigured packages are marked as
3757 requiring configuration, so that if
3758 <tt>--install</tt> is used they will be
3759 configured again if possible.
3762 To prepare for removal of each conflicting package, call:
3763 <example compact="compact">
3764 <var>conflictor's-prerm</var> remove \
3765 in-favour <var>package</var> <var>new-version</var>
3768 <example compact="compact">
3769 <var>conflictor's-postinst</var> abort-remove \
3770 in-favour <var>package</var> <var>new-version</var>
3779 If the package is being upgraded, call:
3780 <example compact="compact">
3781 <var>new-preinst</var> upgrade <var>old-version</var>
3783 If this fails, we call:
3785 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3792 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3794 is called. If this works, then the old version
3795 is in an "Installed" state, or else it is left
3796 in an "Unpacked" state.
3801 If it fails, then the old version is left
3802 in an "Half-Installed" state.
3809 Otherwise, if the package had some configuration
3810 files from a previous version installed (i.e., it
3811 is in the "configuration files only" state):
3812 <example compact="compact">
3813 <var>new-preinst</var> install <var>old-version</var>
3817 <var>new-postrm</var> abort-install <var>old-version</var>
3819 If this fails, the package is left in a
3820 "Half-Installed" state, which requires a
3821 reinstall. If it works, the packages is left in
3822 a "Config Files" state.
3825 Otherwise (i.e., the package was completely purged):
3826 <example compact="compact">
3827 <var>new-preinst</var> install
3830 <example compact="compact">
3831 <var>new-postrm</var> abort-install
3833 If the error-unwind fails, the package is in a
3834 "Half Installed" phase, and requires a
3835 reinstall. If the error unwind works, the
3836 package is in a not installed state.
3843 The new package's files are unpacked, overwriting any
3844 that may be on the system already, for example any
3845 from the old version of the same package or from
3846 another package. Backups of the old files are kept
3847 temporarily, and if anything goes wrong the package
3848 management system will attempt to put them back as
3849 part of the error unwind.
3853 It is an error for a package to contain files which
3854 are on the system in another package, unless
3855 <tt>Replaces</tt> is used (see <ref id="replaces">).
3857 The following paragraph is not currently the case:
3858 Currently the <tt>- - force-overwrite</tt> flag is
3859 enabled, downgrading it to a warning, but this may not
3865 It is a more serious error for a package to contain a
3866 plain file or other kind of non-directory where another
3867 package has a directory (again, unless
3868 <tt>Replaces</tt> is used). This error can be
3869 overridden if desired using
3870 <tt>--force-overwrite-dir</tt>, but this is not
3875 Packages which overwrite each other's files produce
3876 behavior which, though deterministic, is hard for the
3877 system administrator to understand. It can easily
3878 lead to "missing" programs if, for example, a package
3879 is installed which overwrites a file from another
3880 package, and is then removed again.<footnote>
3881 Part of the problem is due to what is arguably a
3882 bug in <prgn>dpkg</prgn>.
3887 A directory will never be replaced by a symbolic link
3888 to a directory or vice versa; instead, the existing
3889 state (symlink or not) will be left alone and
3890 <prgn>dpkg</prgn> will follow the symlink if there is
3899 If the package is being upgraded, call
3900 <example compact="compact">
3901 <var>old-postrm</var> upgrade <var>new-version</var>
3905 If this fails, <prgn>dpkg</prgn> will attempt:
3906 <example compact="compact">
3907 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3909 If this works, installation continues. If not,
3911 <example compact="compact">
3912 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3914 If this fails, the old version is left in an
3915 "Half Installed" state. If it works, dpkg now
3917 <example compact="compact">
3918 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3920 If this fails, the old version is left in an
3921 "Half Installed" state. If it works, dpkg now
3923 <example compact="compact">
3924 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3926 If this fails, the old version is in an
3933 This is the point of no return - if
3934 <prgn>dpkg</prgn> gets this far, it won't back off
3935 past this point if an error occurs. This will
3936 leave the package in a fairly bad state, which
3937 will require a successful re-installation to clear
3938 up, but it's when <prgn>dpkg</prgn> starts doing
3939 things that are irreversible.
3944 Any files which were in the old version of the package
3945 but not in the new are removed.
3949 The new file list replaces the old.
3953 The new maintainer scripts replace the old.
3957 Any packages all of whose files have been overwritten
3958 during the installation, and which aren't required for
3959 dependencies, are considered to have been removed.
3960 For each such package
3963 <prgn>dpkg</prgn> calls:
3964 <example compact="compact">
3965 <var>disappearer's-postrm</var> disappear \
3966 <var>overwriter</var> <var>overwriter-version</var>
3970 The package's maintainer scripts are removed.
3973 It is noted in the status database as being in a
3974 sane state, namely not installed (any conffiles
3975 it may have are ignored, rather than being
3976 removed by <prgn>dpkg</prgn>). Note that
3977 disappearing packages do not have their prerm
3978 called, because <prgn>dpkg</prgn> doesn't know
3979 in advance that the package is going to
3986 Any files in the package we're unpacking that are also
3987 listed in the file lists of other packages are removed
3988 from those lists. (This will lobotomize the file list
3989 of the "conflicting" package if there is one.)
3993 The backup files made during installation, above, are
3999 The new package's status is now sane, and recorded as
4004 Here is another point of no return - if the
4005 conflicting package's removal fails we do not unwind
4006 the rest of the installation; the conflicting package
4007 is left in a half-removed limbo.
4012 If there was a conflicting package we go and do the
4013 removal actions (described below), starting with the
4014 removal of the conflicting package's files (any that
4015 are also in the package being installed have already
4016 been removed from the conflicting package's file list,
4017 and so do not get removed now).
4023 <sect id="configdetails"><heading>Details of configuration</heading>
4026 When we configure a package (this happens with <tt>dpkg
4027 --install</tt> and <tt>dpkg --configure</tt>), we first
4028 update any <tt>conffile</tt>s and then call:
4029 <example compact="compact">
4030 <var>postinst</var> configure <var>most-recently-configured-version</var>
4035 No attempt is made to unwind after errors during
4036 configuration. If the configuration fails, the package is in
4037 a "Failed Config" state, and an error message is generated.
4041 If there is no most recently configured version
4042 <prgn>dpkg</prgn> will pass a null argument.
4045 Historical note: Truly ancient (pre-1997) versions of
4046 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4047 (including the angle brackets) in this case. Even older
4048 ones did not pass a second argument at all, under any
4049 circumstance. Note that upgrades using such an old dpkg
4050 version are unlikely to work for other reasons, even if
4051 this old argument behavior is handled by your postinst script.
4057 <sect id="removedetails"><heading>Details of removal and/or
4058 configuration purging</heading>
4064 <example compact="compact">
4065 <var>prerm</var> remove
4069 If prerm fails during replacement due to conflict
4071 <var>conflictor's-postinst</var> abort-remove \
4072 in-favour <var>package</var> <var>new-version</var>
4076 <var>postinst</var> abort-remove
4080 If this fails, the package is in a "Failed-Config"
4081 state, or else it remains "Installed".
4085 The package's files are removed (except <tt>conffile</tt>s).
4088 <example compact="compact">
4089 <var>postrm</var> remove
4093 If it fails, there's no error unwind, and the package is in
4094 an "Half-Installed" state.
4099 All the maintainer scripts except the <prgn>postrm</prgn>
4104 If we aren't purging the package we stop here. Note
4105 that packages which have no <prgn>postrm</prgn> and no
4106 <tt>conffile</tt>s are automatically purged when
4107 removed, as there is no difference except for the
4108 <prgn>dpkg</prgn> status.
4112 The <tt>conffile</tt>s and any backup files
4113 (<tt>~</tt>-files, <tt>#*#</tt> files,
4114 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4119 <example compact="compact">
4120 <var>postrm</var> purge
4124 If this fails, the package remains in a "Config-Files"
4129 The package's file list is removed.
4138 <chapt id="relationships">
4139 <heading>Declaring relationships between packages</heading>
4141 <sect id="depsyntax">
4142 <heading>Syntax of relationship fields</heading>
4145 These fields all have a uniform syntax. They are a list of
4146 package names separated by commas.
4150 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4151 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4152 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4153 control file fields of the package, which declare
4154 dependencies on other packages, the package names listed may
4155 also include lists of alternative package names, separated
4156 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4157 if any one of the alternative packages is installed, that
4158 part of the dependency is considered to be satisfied.
4162 All of the fields except for <tt>Provides</tt> may restrict
4163 their applicability to particular versions of each named
4164 package. This is done in parentheses after each individual
4165 package name; the parentheses should contain a relation from
4166 the list below followed by a version number, in the format
4167 described in <ref id="f-Version">.
4171 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4172 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4173 strictly earlier, earlier or equal, exactly equal, later or
4174 equal and strictly later, respectively. The deprecated
4175 forms <tt><</tt> and <tt>></tt> were used to mean
4176 earlier/later or equal, rather than strictly earlier/later,
4177 so they should not appear in new packages (though
4178 <prgn>dpkg</prgn> still supports them).
4182 Whitespace may appear at any point in the version
4183 specification subject to the rules in <ref
4184 id="controlsyntax">, and must appear where it's necessary to
4185 disambiguate; it is not otherwise significant. All of the
4186 relationship fields may span multiple lines. For
4187 consistency and in case of future changes to
4188 <prgn>dpkg</prgn> it is recommended that a single space be
4189 used after a version relationship and before a version
4190 number; it is also conventional to put a single space after
4191 each comma, on either side of each vertical bar, and before
4192 each open parenthesis. When wrapping a relationship field, it
4193 is conventional to do so after a comma and before the space
4194 following that comma.
4198 For example, a list of dependencies might appear as:
4199 <example compact="compact">
4202 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4207 All fields that specify build-time relationships
4208 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4209 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4210 may be restricted to a certain set of architectures. This
4211 is indicated in brackets after each individual package name and
4212 the optional version specification. The brackets enclose a
4213 list of Debian architecture names separated by whitespace.
4214 Exclamation marks may be prepended to each of the names.
4215 (It is not permitted for some names to be prepended with
4216 exclamation marks while others aren't.) If the current Debian
4217 host architecture is not in this list and there are no
4218 exclamation marks in the list, or it is in the list with a
4219 prepended exclamation mark, the package name and the
4220 associated version specification are ignored completely for
4221 the purposes of defining the relationships.
4226 <example compact="compact">
4228 Build-Depends-Indep: texinfo
4229 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4230 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4232 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4233 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4234 <tt>gnumach-dev</tt> only on hurd-i386.
4238 If the architecture-restricted dependency is part of a set of
4239 alternatives using <tt>|</tt>, that alternative is ignored
4240 completely on architectures that do not match the restriction.
4242 <example compact="compact">
4243 Build-Depends: foo [!i386] | bar [!amd64]
4245 is equivalent to <tt>bar</tt> on the i386 architecture, to
4246 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4247 bar</tt> on all other architectures.
4251 Note that the binary package relationship fields such as
4252 <tt>Depends</tt> appear in one of the binary package
4253 sections of the control file, whereas the build-time
4254 relationships such as <tt>Build-Depends</tt> appear in the
4255 source package section of the control file (which is the
4260 <sect id="binarydeps">
4261 <heading>Binary Dependencies - <tt>Depends</tt>,
4262 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4263 <tt>Pre-Depends</tt>
4267 Packages can declare in their control file that they have
4268 certain relationships to other packages - for example, that
4269 they may not be installed at the same time as certain other
4270 packages, and/or that they depend on the presence of others.
4274 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4275 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4276 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4277 <tt>Breaks</tt> is described in <ref id="breaks">, and
4278 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4279 rest are described below.
4283 These seven fields are used to declare a dependency
4284 relationship by one package on another. Except for
4285 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4286 depending (binary) package's control file.
4287 (<tt>Enhances</tt> appears in the recommending package's
4288 control file, and <tt>Breaks</tt> appears in the version of
4289 depended-on package which causes the named package to
4294 A <tt>Depends</tt> field takes effect <em>only</em> when a
4295 package is to be configured. It does not prevent a package
4296 being on the system in an unconfigured state while its
4297 dependencies are unsatisfied, and it is possible to replace
4298 a package whose dependencies are satisfied and which is
4299 properly installed with a different version whose
4300 dependencies are not and cannot be satisfied; when this is
4301 done the depending package will be left unconfigured (since
4302 attempts to configure it will give errors) and will not
4303 function properly. If it is necessary, a
4304 <tt>Pre-Depends</tt> field can be used, which has a partial
4305 effect even when a package is being unpacked, as explained
4306 in detail below. (The other three dependency fields,
4307 <tt>Recommends</tt>, <tt>Suggests</tt> and
4308 <tt>Enhances</tt>, are only used by the various front-ends
4309 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4310 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4314 For this reason packages in an installation run are usually
4315 all unpacked first and all configured later; this gives
4316 later versions of packages with dependencies on later
4317 versions of other packages the opportunity to have their
4318 dependencies satisfied.
4322 In case of circular dependencies, since installation or
4323 removal order honoring the dependency order can't be
4324 established, dependency loops are broken at some point
4325 (based on rules below), and some packages may not be able to
4326 rely on their dependencies being present when being
4327 installed or removed, depending on which side of the break
4328 of the circular dependency loop they happen to be on. If one
4329 of the packages in the loop has no postinst script, then the
4330 cycle will be broken at that package, so as to ensure that
4331 all postinst scripts run with the dependencies properly
4332 configured if this is possible. Otherwise the breaking point
4337 The <tt>Depends</tt> field thus allows package maintainers
4338 to impose an order in which packages should be configured.
4342 The meaning of the five dependency fields is as follows:
4344 <tag><tt>Depends</tt></tag>
4347 This declares an absolute dependency. A package will
4348 not be configured unless all of the packages listed in
4349 its <tt>Depends</tt> field have been correctly
4354 The <tt>Depends</tt> field should be used if the
4355 depended-on package is required for the depending
4356 package to provide a significant amount of
4361 The <tt>Depends</tt> field should also be used if the
4362 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4363 <prgn>postrm</prgn> scripts require the package to be
4364 present in order to run. Note, however, that the
4365 <prgn>postrm</prgn> cannot rely on any non-essential
4366 packages to be present during the <tt>purge</tt>
4370 <tag><tt>Recommends</tt></tag>
4373 This declares a strong, but not absolute, dependency.
4377 The <tt>Recommends</tt> field should list packages
4378 that would be found together with this one in all but
4379 unusual installations.
4383 <tag><tt>Suggests</tt></tag>
4385 This is used to declare that one package may be more
4386 useful with one or more others. Using this field
4387 tells the packaging system and the user that the
4388 listed packages are related to this one and can
4389 perhaps enhance its usefulness, but that installing
4390 this one without them is perfectly reasonable.
4393 <tag><tt>Enhances</tt></tag>
4395 This field is similar to Suggests but works in the
4396 opposite direction. It is used to declare that a
4397 package can enhance the functionality of another
4401 <tag><tt>Pre-Depends</tt></tag>
4404 This field is like <tt>Depends</tt>, except that it
4405 also forces <prgn>dpkg</prgn> to complete installation
4406 of the packages named before even starting the
4407 installation of the package which declares the
4408 pre-dependency, as follows:
4412 When a package declaring a pre-dependency is about to
4413 be <em>unpacked</em> the pre-dependency can be
4414 satisfied if the depended-on package is either fully
4415 configured, <em>or even if</em> the depended-on
4416 package(s) are only unpacked or half-configured,
4417 provided that they have been configured correctly at
4418 some point in the past (and not removed or partially
4419 removed since). In this case, both the
4420 previously-configured and currently unpacked or
4421 half-configured versions must satisfy any version
4422 clause in the <tt>Pre-Depends</tt> field.
4426 When the package declaring a pre-dependency is about
4427 to be <em>configured</em>, the pre-dependency will be
4428 treated as a normal <tt>Depends</tt>, that is, it will
4429 be considered satisfied only if the depended-on
4430 package has been correctly configured.
4434 <tt>Pre-Depends</tt> should be used sparingly,
4435 preferably only by packages whose premature upgrade or
4436 installation would hamper the ability of the system to
4437 continue with any upgrade that might be in progress.
4441 <tt>Pre-Depends</tt> are also required if the
4442 <prgn>preinst</prgn> script depends on the named
4443 package. It is best to avoid this situation if
4451 When selecting which level of dependency to use you should
4452 consider how important the depended-on package is to the
4453 functionality of the one declaring the dependency. Some
4454 packages are composed of components of varying degrees of
4455 importance. Such a package should list using
4456 <tt>Depends</tt> the package(s) which are required by the
4457 more important components. The other components'
4458 requirements may be mentioned as Suggestions or
4459 Recommendations, as appropriate to the components' relative
4465 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4468 When one binary package declares that it breaks another,
4469 <prgn>dpkg</prgn> will refuse to allow the package which
4470 declares <tt>Breaks</tt> be installed unless the broken
4471 package is deconfigured first, and it will refuse to
4472 allow the broken package to be reconfigured.
4476 A package will not be regarded as causing breakage merely
4477 because its configuration files are still installed; it must
4478 be at least half-installed.
4482 A special exception is made for packages which declare that
4483 they break their own package name or a virtual package which
4484 they provide (see below): this does not count as a real
4489 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4490 version clause; such a <tt>Breaks</tt> is introduced in the
4491 version of an (implicit or explicit) dependency which
4492 violates an assumption or reveals a bug in earlier versions
4493 of the broken package. This use of <tt>Breaks</tt> will
4494 inform higher-level package management tools that broken
4495 package must be upgraded before the new one.
4499 If the breaking package also overwrites some files from the
4500 older package, it should use <tt>Replaces</tt> (not
4501 <tt>Conflicts</tt>) to ensure this goes smoothly.
4505 <sect id="conflicts">
4506 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4509 When one binary package declares a conflict with another
4510 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4511 refuse to allow them to be installed on the system at the
4516 If one package is to be installed, the other must be removed
4517 first - if the package being installed is marked as
4518 replacing (see <ref id="replaces">) the one on the system,
4519 or the one on the system is marked as deselected, or both
4520 packages are marked <tt>Essential</tt>, then
4521 <prgn>dpkg</prgn> will automatically remove the package
4522 which is causing the conflict, otherwise it will halt the
4523 installation of the new package with an error. This
4524 mechanism is specifically designed to produce an error when
4525 the installed package is <tt>Essential</tt>, but the new
4530 A package will not cause a conflict merely because its
4531 configuration files are still installed; it must be at least
4536 A special exception is made for packages which declare a
4537 conflict with their own package name, or with a virtual
4538 package which they provide (see below): this does not
4539 prevent their installation, and allows a package to conflict
4540 with others providing a replacement for it. You use this
4541 feature when you want the package in question to be the only
4542 package providing some feature.
4546 A <tt>Conflicts</tt> entry should almost never have an
4547 "earlier than" version clause. This would prevent
4548 <prgn>dpkg</prgn> from upgrading or installing the package
4549 which declared such a conflict until the upgrade or removal
4550 of the conflicted-with package had been completed. Instead,
4551 <tt>Breaks</tt> may be used.
4555 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4559 As well as the names of actual ("concrete") packages, the
4560 package relationship fields <tt>Depends</tt>,
4561 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4562 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4563 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4564 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4565 may mention "virtual packages".
4569 A <em>virtual package</em> is one which appears in the
4570 <tt>Provides</tt> control file field of another package.
4571 The effect is as if the package(s) which provide a
4572 particular virtual package name had been listed by name
4573 everywhere the virtual package name appears. (See also <ref
4578 If there are both concrete and virtual packages of the same
4579 name, then the dependency may be satisfied (or the conflict
4580 caused) by either the concrete package with the name in
4581 question or any other concrete package which provides the
4582 virtual package with the name in question. This is so that,
4583 for example, supposing we have
4584 <example compact="compact">
4587 </example> and someone else releases an enhanced version of
4588 the <tt>bar</tt> package they can say:
4589 <example compact="compact">
4593 and the <tt>bar-plus</tt> package will now also satisfy the
4594 dependency for the <tt>foo</tt> package.
4598 If a relationship field has a version number attached
4599 then only real packages will be considered to see whether
4600 the relationship is satisfied (or the prohibition violated,
4601 for a conflict or breakage) - it is assumed that a real
4602 package which provides the virtual package is not of the
4603 "right" version. So, a <tt>Provides</tt> field may not
4604 contain version numbers, and the version number of the
4605 concrete package which provides a particular virtual package
4606 will not be looked at when considering a dependency on or
4607 conflict with the virtual package name.
4611 It is likely that the ability will be added in a future
4612 release of <prgn>dpkg</prgn> to specify a version number for
4613 each virtual package it provides. This feature is not yet
4614 present, however, and is expected to be used only
4619 If you want to specify which of a set of real packages
4620 should be the default to satisfy a particular dependency on
4621 a virtual package, you should list the real package as an
4622 alternative before the virtual one.
4627 <sect id="replaces"><heading>Overwriting files and replacing
4628 packages - <tt>Replaces</tt></heading>
4631 Packages can declare in their control file that they should
4632 overwrite files in certain other packages, or completely
4633 replace other packages. The <tt>Replaces</tt> control file
4634 field has these two distinct purposes.
4637 <sect1><heading>Overwriting files in other packages</heading>
4640 Firstly, as mentioned before, it is usually an error for a
4641 package to contain files which are on the system in
4646 However, if the overwriting package declares that it
4647 <tt>Replaces</tt> the one containing the file being
4648 overwritten, then <prgn>dpkg</prgn> will replace the file
4649 from the old package with that from the new. The file
4650 will no longer be listed as "owned" by the old package.
4654 If a package is completely replaced in this way, so that
4655 <prgn>dpkg</prgn> does not know of any files it still
4656 contains, it is considered to have "disappeared". It will
4657 be marked as not wanted on the system (selected for
4658 removal) and not installed. Any <tt>conffile</tt>s
4659 details noted for the package will be ignored, as they
4660 will have been taken over by the overwriting package. The
4661 package's <prgn>postrm</prgn> script will be run with a
4662 special argument to allow the package to do any final
4663 cleanup required. See <ref id="mscriptsinstact">.
4666 Replaces is a one way relationship -- you have to
4667 install the replacing package after the replaced
4674 For this usage of <tt>Replaces</tt>, virtual packages (see
4675 <ref id="virtual">) are not considered when looking at a
4676 <tt>Replaces</tt> field - the packages declared as being
4677 replaced must be mentioned by their real names.
4681 Furthermore, this usage of <tt>Replaces</tt> only takes
4682 effect when both packages are at least partially on the
4683 system at once, so that it can only happen if they do not
4684 conflict or if the conflict has been overridden.
4689 <sect1><heading>Replacing whole packages, forcing their
4693 Secondly, <tt>Replaces</tt> allows the packaging system to
4694 resolve which package should be removed when there is a
4695 conflict - see <ref id="conflicts">. This usage only
4696 takes effect when the two packages <em>do</em> conflict,
4697 so that the two usages of this field do not interfere with
4702 In this situation, the package declared as being replaced
4703 can be a virtual package, so for example, all mail
4704 transport agents (MTAs) would have the following fields in
4705 their control files:
4706 <example compact="compact">
4707 Provides: mail-transport-agent
4708 Conflicts: mail-transport-agent
4709 Replaces: mail-transport-agent
4711 ensuring that only one MTA can be installed at any one
4716 <sect id="sourcebinarydeps">
4717 <heading>Relationships between source and binary packages -
4718 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4719 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4723 Source packages that require certain binary packages to be
4724 installed or absent at the time of building the package
4725 can declare relationships to those binary packages.
4729 This is done using the <tt>Build-Depends</tt>,
4730 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4731 <tt>Build-Conflicts-Indep</tt> control file fields.
4735 Build-dependencies on "build-essential" binary packages can be
4736 omitted. Please see <ref id="pkg-relations"> for more information.
4740 The dependencies and conflicts they define must be satisfied
4741 (as defined earlier for binary packages) in order to invoke
4742 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4744 If you make "build-arch" or "binary-arch", you need
4745 Build-Depends. If you make "build-indep" or
4746 "binary-indep", you need Build-Depends and
4747 Build-Depends-Indep. If you make "build" or "binary",
4751 There is no Build-Depends-Arch; this role is essentially
4752 met with Build-Depends. Anyone building the
4753 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4754 is basically assumed to be building the whole package
4755 anyway and so installs all build dependencies. The
4756 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4757 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4758 does not yet know how to check for its existence) and
4759 <tt>binary-arch</tt>.
4762 The purpose of the original split, I recall, was so that
4763 the autobuilders wouldn't need to install extra packages
4764 needed only for the binary-indep targets. But without a
4765 build-arch/build-indep split, this didn't work, since
4766 most of the work is done in the build target, not in the
4772 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4774 The <tt>Build-Depends</tt> and
4775 <tt>Build-Conflicts</tt> fields must be satisfied when
4776 any of the following targets is invoked:
4777 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4778 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4779 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4781 <tag><tt>Build-Depends-Indep</tt>,
4782 <tt>Build-Conflicts-Indep</tt></tag>
4784 The <tt>Build-Depends-Indep</tt> and
4785 <tt>Build-Conflicts-Indep</tt> fields must be
4786 satisfied when any of the following targets is
4787 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4788 <tt>binary</tt> and <tt>binary-indep</tt>.
4798 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4801 Packages containing shared libraries must be constructed with
4802 a little care to make sure that the shared library is always
4803 available. This is especially important for packages whose
4804 shared libraries are vitally important, such as the C library
4805 (currently <tt>libc6</tt>).
4809 Packages involving shared libraries should be split up into
4810 several binary packages. This section mostly deals with how
4811 this separation is to be accomplished; rules for files within
4812 the shared library packages are in <ref id="libraries"> instead.
4815 <sect id="sharedlibs-runtime">
4816 <heading>Run-time shared libraries</heading>
4819 The run-time shared library needs to be placed in a package
4820 whose name changes whenever the shared object version
4823 Since it is common place to install several versions of a
4824 package that just provides shared libraries, it is a
4825 good idea that the library package should not
4826 contain any extraneous non-versioned files, unless they
4827 happen to be in versioned directories.</p>
4829 The most common mechanism is to place it in a package
4831 <package><var>libraryname</var><var>soversion</var></package>,
4832 where <file><var>soversion</var></file> is the version number
4833 in the soname of the shared library<footnote>
4834 The soname is the shared object name: it's the thing
4835 that has to match exactly between building an executable
4836 and running it for the dynamic linker to be able run the
4837 program. For example, if the soname of the library is
4838 <file>libfoo.so.6</file>, the library package would be
4839 called <file>libfoo6</file>.
4841 Alternatively, if it would be confusing to directly append
4842 <var>soversion</var> to <var>libraryname</var> (e.g. because
4843 <var>libraryname</var> itself ends in a number), you may use
4844 <package><var>libraryname</var>-<var>soversion</var></package> and
4845 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4850 If you have several shared libraries built from the same
4851 source tree you may lump them all together into a single
4852 shared library package, provided that you change all of
4853 their sonames at once (so that you don't get filename
4854 clashes if you try to install different versions of the
4855 combined shared libraries package).
4859 The package should install the shared libraries under
4860 their normal names. For example, the <package>libgdbm3</package>
4861 package should install <file>libgdbm.so.3.0.0</file> as
4862 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4863 renamed or re-linked by any <prgn>prerm</prgn> or
4864 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4865 of renaming things safely without affecting running programs,
4866 and attempts to interfere with this are likely to lead to
4871 Shared libraries should not be installed executable, since
4872 the dynamic linker does not require this and trying to
4873 execute a shared library usually results in a core dump.
4877 The run-time library package should include the symbolic link that
4878 <prgn>ldconfig</prgn> would create for the shared libraries.
4879 For example, the <package>libgdbm3</package> package should include
4880 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4881 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4882 linker (for example <prgn>ld.so</prgn> or
4883 <prgn>ld-linux.so.*</prgn>) can find the library between the
4884 time that <prgn>dpkg</prgn> installs it and the time that
4885 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4887 The package management system requires the library to be
4888 placed before the symbolic link pointing to it in the
4889 <file>.deb</file> file. This is so that when
4890 <prgn>dpkg</prgn> comes to install the symlink
4891 (overwriting the previous symlink pointing at an older
4892 version of the library), the new shared library is already
4893 in place. In the past, this was achieved by creating the
4894 library in the temporary packaging directory before
4895 creating the symlink. Unfortunately, this was not always
4896 effective, since the building of the tar file in the
4897 <file>.deb</file> depended on the behavior of the underlying
4898 file system. Some file systems (such as reiserfs) reorder
4899 the files so that the order of creation is forgotten.
4900 Since version 1.7.0, <prgn>dpkg</prgn>
4901 reorders the files itself as necessary when building a
4902 package. Thus it is no longer important to concern
4903 oneself with the order of file creation.
4907 <sect1 id="ldconfig">
4908 <heading><tt>ldconfig</tt></heading>
4911 Any package installing shared libraries in one of the default
4912 library directories of the dynamic linker (which are currently
4913 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4914 listed in <file>/etc/ld.so.conf</file><footnote>
4916 <list compact="compact">
4917 <item>/usr/local/lib</item>
4918 <item>/usr/lib/libc5-compat</item>
4919 <item>/lib/libc5-compat</item>
4922 must use <prgn>ldconfig</prgn> to update the shared library
4927 The package maintainer scripts must only call
4928 <prgn>ldconfig</prgn> under these circumstances:
4929 <list compact="compact">
4930 <item>When the <prgn>postinst</prgn> script is run with a
4931 first argument of <tt>configure</tt>, the script must call
4932 <prgn>ldconfig</prgn>, and may optionally invoke
4933 <prgn>ldconfig</prgn> at other times.
4935 <item>When the <prgn>postrm</prgn> script is run with a
4936 first argument of <tt>remove</tt>, the script should call
4937 <prgn>ldconfig</prgn>.
4942 During install or upgrade, the preinst is called before
4943 the new files are installed, so calling "ldconfig" is
4944 pointless. The preinst of an existing package can also be
4945 called if an upgrade fails. However, this happens during
4946 the critical time when a shared libs may exist on-disk
4947 under a temporary name. Thus, it is dangerous and
4948 forbidden by current policy to call "ldconfig" at this
4953 When a package is installed or upgraded, "postinst
4954 configure" runs after the new files are safely on-disk.
4955 Since it is perfectly safe to invoke ldconfig
4956 unconditionally in a postinst, it is OK for a package to
4957 simply put ldconfig in its postinst without checking the
4958 argument. The postinst can also be called to recover from
4959 a failed upgrade. This happens before any new files are
4960 unpacked, so there is no reason to call "ldconfig" at this
4965 For a package that is being removed, prerm is
4966 called with all the files intact, so calling ldconfig is
4967 useless. The other calls to "prerm" happen in the case of
4968 upgrade at a time when all the files of the old package
4969 are on-disk, so again calling "ldconfig" is pointless.
4973 postrm, on the other hand, is called with the "remove"
4974 argument just after the files are removed, so this is
4975 the proper time to call "ldconfig" to notify the system
4976 of the fact that the shared libraries from the package
4977 are removed. The postrm can be called at several other
4978 times. At the time of "postrm purge", "postrm
4979 abort-install", or "postrm abort-upgrade", calling
4980 "ldconfig" is useless because the shared lib files are
4981 not on-disk. However, when "postrm" is invoked with
4982 arguments "upgrade", "failed-upgrade", or "disappear", a
4983 shared lib may exist on-disk under a temporary filename.
4991 <sect id="sharedlibs-support-files">
4992 <heading>Shared library support files</heading>
4995 If your package contains files whose names do not change with
4996 each change in the library shared object version, you must not
4997 put them in the shared library package. Otherwise, several
4998 versions of the shared library cannot be installed at the same
4999 time without filename clashes, making upgrades and transitions
5000 unnecessarily difficult.
5004 It is recommended that supporting files and run-time support
5005 programs that do not need to be invoked manually by users, but
5006 are nevertheless required for the package to function, be placed
5007 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5008 preferably under <file>/usr/lib/</file><var>package-name</var>.
5009 If the program or file is architecture independent, the
5010 recommendation is for it to be placed in a subdirectory of
5011 <file>/usr/share</file> instead, preferably under
5012 <file>/usr/share/</file><var>package-name</var>. Following the
5013 <var>package-name</var> naming convention ensures that the file
5014 names change when the shared object version changes.
5018 Run-time support programs that use the shared library but are
5019 not required for the library to function or files used by the
5020 shared library that can be used by any version of the shared
5021 library package should instead be put in a separate package.
5022 This package might typically be named
5023 <package><var>libraryname</var>-tools</package>; note the
5024 absence of the <var>soversion</var> in the package name.
5028 Files and support programs only useful when compiling software
5029 against the library should be included in the development
5030 package for the library.<footnote>
5031 For example, a <file><var>package-name</var>-config</file>
5032 script or <package>pkg-config</package> configuration files.
5037 <sect id="sharedlibs-static">
5038 <heading>Static libraries</heading>
5041 The static library (<file><var>libraryname.a</var></file>)
5042 is usually provided in addition to the shared version.
5043 It is placed into the development package (see below).
5047 In some cases, it is acceptable for a library to be
5048 available in static form only; these cases include:
5050 <item>libraries for languages whose shared library support
5051 is immature or unstable</item>
5052 <item>libraries whose interfaces are in flux or under
5053 development (commonly the case when the library's
5054 major version number is zero, or where the ABI breaks
5055 across patchlevels)</item>
5056 <item>libraries which are explicitly intended to be
5057 available only in static form by their upstream
5062 <sect id="sharedlibs-dev">
5063 <heading>Development files</heading>
5066 The development files associated to a shared library need to be
5067 placed in a package called
5068 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5069 or if you prefer only to support one development version at a
5070 time, <package><var>libraryname</var>-dev</package>.
5074 In case several development versions of a library exist, you may
5075 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5076 <ref id="conflicts">) to ensure that the user only installs one
5077 development version at a time (as different development versions are
5078 likely to have the same header files in them, which would cause a
5079 filename clash if both were installed).
5083 The development package should contain a symlink for the associated
5084 shared library without a version number. For example, the
5085 <package>libgdbm-dev</package> package should include a symlink
5086 from <file>/usr/lib/libgdbm.so</file> to
5087 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5088 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5089 <file>libgdbm.so</file> when compiling dynamically.
5093 <sect id="sharedlibs-intradeps">
5094 <heading>Dependencies between the packages of the same library</heading>
5097 Typically the development version should have an exact
5098 version dependency on the runtime library, to make sure that
5099 compilation and linking happens correctly. The
5100 <tt>${binary:Version}</tt> substitution variable can be
5101 useful for this purpose.
5103 Previously, <tt>${Source-Version}</tt> was used, but its name
5104 was confusing and it has been deprecated since dpkg 1.13.19.
5109 <sect id="sharedlibs-shlibdeps">
5110 <heading>Dependencies between the library and other packages -
5111 the <tt>shlibs</tt> system</heading>
5114 If a package contains a binary or library which links to a
5115 shared library, we must ensure that when the package is
5116 installed on the system, all of the libraries needed are
5117 also installed. This requirement led to the creation of the
5118 <tt>shlibs</tt> system, which is very simple in its design:
5119 any package which <em>provides</em> a shared library also
5120 provides information on the package dependencies required to
5121 ensure the presence of this library, and any package which
5122 <em>uses</em> a shared library uses this information to
5123 determine the dependencies it requires. The files which
5124 contain the mapping from shared libraries to the necessary
5125 dependency information are called <file>shlibs</file> files.
5129 Thus, when a package is built which contains any shared
5130 libraries, it must provide a <file>shlibs</file> file for other
5131 packages to use, and when a package is built which contains
5132 any shared libraries or compiled binaries, it must run
5133 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5134 on these to determine the libraries used and hence the
5135 dependencies needed by this package.<footnote>
5137 In the past, the shared libraries linked to were
5138 determined by calling <prgn>ldd</prgn>, but now
5139 <prgn>objdump</prgn> is used to do this. The only
5140 change this makes to package building is that
5141 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5142 libraries, whereas in the past this was unnecessary.
5143 The rest of this footnote explains the advantage that
5148 We say that a binary <tt>foo</tt> <em>directly</em> uses
5149 a library <tt>libbar</tt> if it is explicitly linked
5150 with that library (that is, it uses the flag
5151 <tt>-lbar</tt> during the linking stage). Other
5152 libraries that are needed by <tt>libbar</tt> are linked
5153 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5154 linker will load them automatically when it loads
5155 <tt>libbar</tt>. A package should depend on
5156 the libraries it directly uses, and the dependencies for
5157 those libraries should automatically pull in the other
5162 Unfortunately, the <prgn>ldd</prgn> program shows both
5163 the directly and indirectly used libraries, meaning that
5164 the dependencies determined included both direct and
5165 indirect dependencies. The use of <prgn>objdump</prgn>
5166 avoids this problem by determining only the directly
5171 A good example of where this helps is the following. We
5172 could update <tt>libimlib</tt> with a new version that
5173 supports a new graphics format called dgf (but retaining
5174 the same major version number). If we used the old
5175 <prgn>ldd</prgn> method, every package that uses
5176 <tt>libimlib</tt> would need to be recompiled so it
5177 would also depend on <tt>libdgf</tt> or it wouldn't run
5178 due to missing symbols. However with the new system,
5179 packages using <tt>libimlib</tt> can rely on
5180 <tt>libimlib</tt> itself having the dependency on
5181 <tt>libdgf</tt> and so they would not need rebuilding.
5187 In the following sections, we will first describe where the
5188 various <tt>shlibs</tt> files are to be found, then how to
5189 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5190 file format and how to create them if your package contains a
5195 <heading>The <tt>shlibs</tt> files present on the system</heading>
5198 There are several places where <tt>shlibs</tt> files are
5199 found. The following list gives them in the order in which
5201 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5202 (The first one which gives the required information is used.)
5208 <p><file>debian/shlibs.local</file></p>
5211 This lists overrides for this package. Its use is
5212 described below (see <ref id="shlibslocal">).
5217 <p><file>/etc/dpkg/shlibs.override</file></p>
5220 This lists global overrides. This list is normally
5221 empty. It is maintained by the local system
5227 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5230 When packages are being built, any
5231 <file>debian/shlibs</file> files are copied into the
5232 control file area of the temporary build directory and
5233 given the name <file>shlibs</file>. These files give
5234 details of any shared libraries included in the
5236 An example may help here. Let us say that the
5237 source package <tt>foo</tt> generates two binary
5238 packages, <tt>libfoo2</tt> and
5239 <tt>foo-runtime</tt>. When building the binary
5240 packages, the two packages are created in the
5241 directories <file>debian/libfoo2</file> and
5242 <file>debian/foo-runtime</file> respectively.
5243 (<file>debian/tmp</file> could be used instead of one
5244 of these.) Since <tt>libfoo2</tt> provides the
5245 <tt>libfoo</tt> shared library, it will require a
5246 <tt>shlibs</tt> file, which will be installed in
5247 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5249 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5250 when <prgn>dpkg-shlibdeps</prgn> is run on the
5252 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5254 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5255 determine whether <tt>foo-prog</tt>'s library
5256 dependencies are satisfied by any of the libraries
5257 provided by <tt>libfoo2</tt>. For this reason,
5258 <prgn>dpkg-shlibdeps</prgn> must only be run once
5259 all of the individual binary packages'
5260 <tt>shlibs</tt> files have been installed into the
5267 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5270 These are the <file>shlibs</file> files corresponding to
5271 all of the packages installed on the system, and are
5272 maintained by the relevant package maintainers.
5277 <p><file>/etc/dpkg/shlibs.default</file></p>
5280 This file lists any shared libraries whose packages
5281 have failed to provide correct <file>shlibs</file> files.
5282 It was used when the <file>shlibs</file> setup was first
5283 introduced, but it is now normally empty. It is
5284 maintained by the <tt>dpkg</tt> maintainer.
5292 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5293 <file>shlibs</file> files</heading>
5297 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5298 into your <file>debian/rules</file> file. If your package
5299 contains only compiled binaries and libraries (but no scripts),
5300 you can use a command such as:
5301 <example compact="compact">
5302 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5303 debian/tmp/usr/lib/*
5305 Otherwise, you will need to explicitly list the compiled
5306 binaries and libraries.<footnote>
5307 If you are using <tt>debhelper</tt>, the
5308 <prgn>dh_shlibdeps</prgn> program will do this work for
5309 you. It will also correctly handle multi-binary
5315 This command puts the dependency information into the
5316 <file>debian/substvars</file> file, which is then used by
5317 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5318 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5319 field in the control file for this to work.
5323 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5324 done. If it does complain you might need to create your own
5325 <file>debian/shlibs.local</file> file, as explained below (see
5326 <ref id="shlibslocal">).
5330 If you have multiple binary packages, you will need to call
5331 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5332 compiled libraries or binaries. In such a case, you will
5333 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5334 utilities to specify a different <file>substvars</file> file.
5338 If you are creating a udeb for use in the Debian Installer, you
5339 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5340 the dependency line of type <tt>udeb</tt> by adding
5341 <tt>-tudeb</tt> as option<footnote>
5342 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5343 will automatically add this option if it knows it is
5345 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5346 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5347 fall back to the regular dependency line.
5351 For more details on dpkg-shlibdeps, please see
5352 <ref id="pkg-dpkg-shlibdeps"> and
5353 <manref name="dpkg-shlibdeps" section="1">.
5358 <heading>The <file>shlibs</file> File Format</heading>
5361 Each <file>shlibs</file> file has the same format. Lines
5362 beginning with <tt>#</tt> are considered to be comments and
5363 are ignored. Each line is of the form:
5364 <example compact="compact">
5365 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5370 We will explain this by reference to the example of the
5371 <tt>zlib1g</tt> package, which (at the time of writing)
5372 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5376 <var>type</var> is an optional element that indicates the type
5377 of package for which the line is valid. The only type currently
5378 in use is <tt>udeb</tt>. The colon and space after the type are
5383 <var>library-name</var> is the name of the shared library,
5384 in this case <tt>libz</tt>. (This must match the name part
5385 of the soname, see below.)
5389 <var>soname-version</var> is the version part of the soname of
5390 the library. The soname is the thing that must exactly match
5391 for the library to be recognized by the dynamic linker, and is
5393 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5394 example, <tt>libz.so.1</tt>.<footnote>
5395 This can be determined using the command
5396 <example compact="compact">
5397 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5400 The version part is the part which comes after
5401 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5405 <var>dependencies</var> has the same syntax as a dependency
5406 field in a binary package control file. It should give
5407 details of which packages are required to satisfy a binary
5408 built against the version of the library contained in the
5409 package. See <ref id="depsyntax"> for details.
5413 In our example, if the first version of the <tt>zlib1g</tt>
5414 package which contained a minor number of at least
5415 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5416 <tt>shlibs</tt> entry for this library could say:
5417 <example compact="compact">
5418 libz 1 zlib1g (>= 1:1.1.3)
5420 The version-specific dependency is to avoid warnings from
5421 the dynamic linker about using older shared libraries with
5426 As zlib1g also provides a udeb containing the shared library,
5427 there would also be a second line:
5428 <example compact="compact">
5429 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5435 <heading>Providing a <file>shlibs</file> file</heading>
5438 If your package provides a shared library, you need to create
5439 a <file>shlibs</file> file following the format described above.
5440 It is usual to call this file <file>debian/shlibs</file> (but if
5441 you have multiple binary packages, you might want to call it
5442 <file>debian/shlibs.<var>package</var></file> instead). Then
5443 let <file>debian/rules</file> install it in the control area:
5444 <example compact="compact">
5445 install -m644 debian/shlibs debian/tmp/DEBIAN
5447 or, in the case of a multi-binary package:
5448 <example compact="compact">
5449 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5451 An alternative way of doing this is to create the
5452 <file>shlibs</file> file in the control area directly from
5453 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5454 file at all,<footnote>
5455 This is what <prgn>dh_makeshlibs</prgn> in the
5456 <tt>debhelper</tt> suite does. If your package also has a udeb
5457 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5458 automatically generate the <tt>udeb:</tt> lines if you specify
5459 the name of the udeb with the <tt>--add-udeb</tt> option.
5461 since the <file>debian/shlibs</file> file itself is ignored by
5462 <prgn>dpkg-shlibdeps</prgn>.
5466 As <prgn>dpkg-shlibdeps</prgn> reads the
5467 <file>DEBIAN/shlibs</file> files in all of the binary packages
5468 being built from this source package, all of the
5469 <file>DEBIAN/shlibs</file> files should be installed before
5470 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5475 <sect1 id="shlibslocal">
5476 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5479 This file is intended only as a <em>temporary</em> fix if
5480 your binaries or libraries depend on a library whose package
5481 does not yet provide a correct <file>shlibs</file> file.
5485 We will assume that you are trying to package a binary
5486 <tt>foo</tt>. When you try running
5487 <prgn>dpkg-shlibdeps</prgn> you get the following error
5488 message (<tt>-O</tt> displays the dependency information on
5489 <tt>stdout</tt> instead of writing it to
5490 <tt>debian/substvars</tt>, and the lines have been wrapped
5491 for ease of reading):
5492 <example compact="compact">
5493 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5494 dpkg-shlibdeps: warning: unable to find dependency
5495 information for shared library libbar (soname 1,
5496 path /usr/lib/libbar.so.1, dependency field Depends)
5497 shlibs:Depends=libc6 (>= 2.2.2-2)
5499 You can then run <prgn>ldd</prgn> on the binary to find the
5500 full location of the library concerned:
5501 <example compact="compact">
5503 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5504 libc.so.6 => /lib/libc.so.6 (0x40032000)
5505 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5507 So the <prgn>foo</prgn> binary depends on the
5508 <prgn>libbar</prgn> shared library, but no package seems to
5509 provide a <file>*.shlibs</file> file handling
5510 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5511 determine the package responsible:
5512 <example compact="compact">
5513 $ dpkg -S /usr/lib/libbar.so.1
5514 bar1: /usr/lib/libbar.so.1
5515 $ dpkg -s bar1 | grep Version
5518 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5519 is the one we are using. Now we can file a bug against the
5520 <tt>bar1</tt> package and create our own
5521 <file>debian/shlibs.local</file> to locally fix the problem.
5522 Including the following line into your
5523 <file>debian/shlibs.local</file> file:
5524 <example compact="compact">
5525 libbar 1 bar1 (>= 1.0-1)
5527 should allow the package build to work.
5531 As soon as the maintainer of <tt>bar1</tt> provides a
5532 correct <file>shlibs</file> file, you should remove this line
5533 from your <file>debian/shlibs.local</file> file. (You should
5534 probably also then have a versioned <tt>Build-Depends</tt>
5535 on <tt>bar1</tt> to help ensure that others do not have the
5536 same problem building your package.)
5545 <chapt id="opersys"><heading>The Operating System</heading>
5548 <heading>File system hierarchy</heading>
5552 <heading>File System Structure</heading>
5555 The location of all installed files and directories must
5556 comply with the Filesystem Hierarchy Standard (FHS),
5557 version 2.3, with the exceptions noted below, and except
5558 where doing so would violate other terms of Debian
5559 Policy. The following exceptions to the FHS apply:
5564 The optional rules related to user specific
5565 configuration files for applications are stored in
5566 the user's home directory are relaxed. It is
5567 recommended that such files start with the
5568 '<tt>.</tt>' character (a "dot file"), and if an
5569 application needs to create more than one dot file
5570 then the preferred placement is in a subdirectory
5571 with a name starting with a '.' character, (a "dot
5572 directory"). In this case it is recommended the
5573 configuration files not start with the '.'
5579 The requirement for amd64 to use <file>/lib64</file>
5580 for 64 bit binaries is removed.
5585 The requirement that
5586 <file>/usr/local/share/man</file> be "synonymous"
5587 with <file>/usr/local/man</file> is relaxed to a
5592 The requirement that windowmanagers with a single
5593 configuration file call it <file>system.*wmrc</file>
5594 is removed, as is the restriction that the window
5595 manager subdirectory be named identically to the
5596 window manager name itself.
5601 The requirement that boot manager configuration
5602 files live in <file>/etc</file>, or at least are
5603 symlinked there, is relaxed to a recommendation.
5610 The version of this document referred here can be
5611 found in the <tt>debian-policy</tt> package or on <url
5612 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5613 name="FHS (Debian copy)"> alongside this manual (or, if
5614 you have the <package>debian-policy</package> installed,
5616 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5617 (local copy)">). The
5618 latest version, which may be a more recent version, may
5620 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5621 Specific questions about following the standard may be
5622 asked on the <tt>debian-devel</tt> mailing list, or
5623 referred to the FHS mailing list (see the
5624 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5630 <heading>Site-specific programs</heading>
5633 As mandated by the FHS, packages must not place any
5634 files in <file>/usr/local</file>, either by putting them in
5635 the file system archive to be unpacked by <prgn>dpkg</prgn>
5636 or by manipulating them in their maintainer scripts.
5640 However, the package may create empty directories below
5641 <file>/usr/local</file> so that the system administrator knows
5642 where to place site-specific files. These are not
5643 directories <em>in</em> <file>/usr/local</file>, but are
5644 children of directories in <file>/usr/local</file>. These
5645 directories (<file>/usr/local/*/dir/</file>)
5646 should be removed on package removal if they are
5651 Note, that this applies only to directories <em>below</em>
5652 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5653 Packages must not create sub-directories in the directory
5654 <file>/usr/local</file> itself, except those listed in FHS,
5655 section 4.5. However, you may create directories below
5656 them as you wish. You must not remove any of the
5657 directories listed in 4.5, even if you created them.
5661 Since <file>/usr/local</file> can be mounted read-only from a
5662 remote server, these directories must be created and
5663 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5664 maintainer scripts and not be included in the
5665 <file>.deb</file> archive. These scripts must not fail if
5666 either of these operations fail.
5670 For example, the <tt>emacsen-common</tt> package could
5671 contain something like
5672 <example compact="compact">
5673 if [ ! -e /usr/local/share/emacs ]
5675 if mkdir /usr/local/share/emacs 2>/dev/null
5677 chown root:staff /usr/local/share/emacs
5678 chmod 2775 /usr/local/share/emacs
5682 in its <prgn>postinst</prgn> script, and
5683 <example compact="compact">
5684 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5685 rmdir /usr/local/share/emacs 2>/dev/null || true
5687 in the <prgn>prerm</prgn> script. (Note that this form is
5688 used to ensure that if the script is interrupted, the
5689 directory <file>/usr/local/share/emacs</file> will still be
5694 If you do create a directory in <file>/usr/local</file> for
5695 local additions to a package, you should ensure that
5696 settings in <file>/usr/local</file> take precedence over the
5697 equivalents in <file>/usr</file>.
5701 However, because <file>/usr/local</file> and its contents are
5702 for exclusive use of the local administrator, a package
5703 must not rely on the presence or absence of files or
5704 directories in <file>/usr/local</file> for normal operation.
5708 The <file>/usr/local</file> directory itself and all the
5709 subdirectories created by the package should (by default) have
5710 permissions 2775 (group-writable and set-group-id) and be
5711 owned by <tt>root:staff</tt>.
5716 <heading>The system-wide mail directory</heading>
5718 The system-wide mail directory is <file>/var/mail</file>. This
5719 directory is part of the base system and should not owned
5720 by any particular mail agents. The use of the old
5721 location <file>/var/spool/mail</file> is deprecated, even
5722 though the spool may still be physically located there.
5728 <heading>Users and groups</heading>
5731 <heading>Introduction</heading>
5733 The Debian system can be configured to use either plain or
5738 Some user ids (UIDs) and group ids (GIDs) are reserved
5739 globally for use by certain packages. Because some
5740 packages need to include files which are owned by these
5741 users or groups, or need the ids compiled into binaries,
5742 these ids must be used on any Debian system only for the
5743 purpose for which they are allocated. This is a serious
5744 restriction, and we should avoid getting in the way of
5745 local administration policies. In particular, many sites
5746 allocate users and/or local system groups starting at 100.
5750 Apart from this we should have dynamically allocated ids,
5751 which should by default be arranged in some sensible
5752 order, but the behavior should be configurable.
5756 Packages other than <tt>base-passwd</tt> must not modify
5757 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5758 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5763 <heading>UID and GID classes</heading>
5765 The UID and GID numbers are divided into classes as
5771 Globally allocated by the Debian project, the same
5772 on every Debian system. These ids will appear in
5773 the <file>passwd</file> and <file>group</file> files of all
5774 Debian systems, new ids in this range being added
5775 automatically as the <tt>base-passwd</tt> package is
5780 Packages which need a single statically allocated
5781 uid or gid should use one of these; their
5782 maintainers should ask the <tt>base-passwd</tt>
5790 Dynamically allocated system users and groups.
5791 Packages which need a user or group, but can have
5792 this user or group allocated dynamically and
5793 differently on each system, should use <tt>adduser
5794 --system</tt> to create the group and/or user.
5795 <prgn>adduser</prgn> will check for the existence of
5796 the user or group, and if necessary choose an unused
5797 id based on the ranges specified in
5798 <file>adduser.conf</file>.
5802 <tag>1000-29999:</tag>
5805 Dynamically allocated user accounts. By default
5806 <prgn>adduser</prgn> will choose UIDs and GIDs for
5807 user accounts in this range, though
5808 <file>adduser.conf</file> may be used to modify this
5813 <tag>30000-59999:</tag>
5818 <tag>60000-64999:</tag>
5821 Globally allocated by the Debian project, but only
5822 created on demand. The ids are allocated centrally
5823 and statically, but the actual accounts are only
5824 created on users' systems on demand.
5828 These ids are for packages which are obscure or
5829 which require many statically-allocated ids. These
5830 packages should check for and create the accounts in
5831 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5832 <prgn>adduser</prgn> if it has this facility) if
5833 necessary. Packages which are likely to require
5834 further allocations should have a "hole" left after
5835 them in the allocation, to give them room to
5840 <tag>65000-65533:</tag>
5848 User <tt>nobody</tt>. The corresponding gid refers
5849 to the group <tt>nogroup</tt>.
5856 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5857 not</em> be used, because it is the error return
5866 <sect id="sysvinit">
5867 <heading>System run levels and <file>init.d</file> scripts</heading>
5869 <sect1 id="/etc/init.d">
5870 <heading>Introduction</heading>
5873 The <file>/etc/init.d</file> directory contains the scripts
5874 executed by <prgn>init</prgn> at boot time and when the
5875 init state (or "runlevel") is changed (see <manref
5876 name="init" section="8">).
5880 There are at least two different, yet functionally
5881 equivalent, ways of handling these scripts. For the sake
5882 of simplicity, this document describes only the symbolic
5883 link method. However, it must not be assumed by maintainer
5884 scripts that this method is being used, and any automated
5885 manipulation of the various runlevel behaviors by
5886 maintainer scripts must be performed using
5887 <prgn>update-rc.d</prgn> as described below and not by
5888 manually installing or removing symlinks. For information
5889 on the implementation details of the other method,
5890 implemented in the <tt>file-rc</tt> package, please refer
5891 to the documentation of that package.
5895 These scripts are referenced by symbolic links in the
5896 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5897 runlevels, <prgn>init</prgn> looks in the directory
5898 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5899 execute, where <tt><var>n</var></tt> is the runlevel that
5900 is being changed to, or <tt>S</tt> for the boot-up
5905 The names of the links all have the form
5906 <file>S<var>mm</var><var>script</var></file> or
5907 <file>K<var>mm</var><var>script</var></file> where
5908 <var>mm</var> is a two-digit number and <var>script</var>
5909 is the name of the script (this should be the same as the
5910 name of the actual script in <file>/etc/init.d</file>).
5914 When <prgn>init</prgn> changes runlevel first the targets
5915 of the links whose names start with a <tt>K</tt> are
5916 executed, each with the single argument <tt>stop</tt>,
5917 followed by the scripts prefixed with an <tt>S</tt>, each
5918 with the single argument <tt>start</tt>. (The links are
5919 those in the <file>/etc/rc<var>n</var>.d</file> directory
5920 corresponding to the new runlevel.) The <tt>K</tt> links
5921 are responsible for killing services and the <tt>S</tt>
5922 link for starting services upon entering the runlevel.
5926 For example, if we are changing from runlevel 2 to
5927 runlevel 3, init will first execute all of the <tt>K</tt>
5928 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5929 all of the <tt>S</tt> prefixed scripts in that directory.
5930 The links starting with <tt>K</tt> will cause the
5931 referred-to file to be executed with an argument of
5932 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5937 The two-digit number <var>mm</var> is used to determine
5938 the order in which to run the scripts: low-numbered links
5939 have their scripts run first. For example, the
5940 <tt>K20</tt> scripts will be executed before the
5941 <tt>K30</tt> scripts. This is used when a certain service
5942 must be started before another. For example, the name
5943 server <prgn>bind</prgn> might need to be started before
5944 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5945 can set up its access lists. In this case, the script
5946 that starts <prgn>bind</prgn> would have a lower number
5947 than the script that starts <prgn>inn</prgn> so that it
5949 <example compact="compact">
5956 The two runlevels 0 (halt) and 6 (reboot) are slightly
5957 different. In these runlevels, the links with an
5958 <tt>S</tt> prefix are still called after those with a
5959 <tt>K</tt> prefix, but they too are called with the single
5960 argument <tt>stop</tt>.
5965 <heading>Writing the scripts</heading>
5968 Packages that include daemons for system services should
5969 place scripts in <file>/etc/init.d</file> to start or stop
5970 services at boot time or during a change of runlevel.
5971 These scripts should be named
5972 <file>/etc/init.d/<var>package</var></file>, and they should
5973 accept one argument, saying what to do:
5976 <tag><tt>start</tt></tag>
5977 <item>start the service,</item>
5979 <tag><tt>stop</tt></tag>
5980 <item>stop the service,</item>
5982 <tag><tt>restart</tt></tag>
5983 <item>stop and restart the service if it's already running,
5984 otherwise start the service</item>
5986 <tag><tt>reload</tt></tag>
5987 <item><p>cause the configuration of the service to be
5988 reloaded without actually stopping and restarting
5991 <tag><tt>force-reload</tt></tag>
5992 <item>cause the configuration to be reloaded if the
5993 service supports this, otherwise restart the
5997 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5998 <tt>force-reload</tt> options should be supported by all
5999 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6004 The <file>init.d</file> scripts must ensure that they will
6005 behave sensibly (i.e., returning success and not starting
6006 multiple copies of a service) if invoked with <tt>start</tt>
6007 when the service is already running, or with <tt>stop</tt>
6008 when it isn't, and that they don't kill unfortunately-named
6009 user processes. The best way to achieve this is usually to
6010 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6015 If a service reloads its configuration automatically (as
6016 in the case of <prgn>cron</prgn>, for example), the
6017 <tt>reload</tt> option of the <file>init.d</file> script
6018 should behave as if the configuration has been reloaded
6023 The <file>/etc/init.d</file> scripts must be treated as
6024 configuration files, either (if they are present in the
6025 package, that is, in the .deb file) by marking them as
6026 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6027 by managing them correctly in the maintainer scripts (see
6028 <ref id="config-files">). This is important since we want
6029 to give the local system administrator the chance to adapt
6030 the scripts to the local system, e.g., to disable a
6031 service without de-installing the package, or to specify
6032 some special command line options when starting a service,
6033 while making sure their changes aren't lost during the next
6038 These scripts should not fail obscurely when the
6039 configuration files remain but the package has been
6040 removed, as configuration files remain on the system after
6041 the package has been removed. Only when <prgn>dpkg</prgn>
6042 is executed with the <tt>--purge</tt> option will
6043 configuration files be removed. In particular, as the
6044 <file>/etc/init.d/<var>package</var></file> script itself is
6045 usually a <tt>conffile</tt>, it will remain on the system
6046 if the package is removed but not purged. Therefore, you
6047 should include a <tt>test</tt> statement at the top of the
6049 <example compact="compact">
6050 test -f <var>program-executed-later-in-script</var> || exit 0
6055 Often there are some variables in the <file>init.d</file>
6056 scripts whose values control the behavior of the scripts,
6057 and which a system administrator is likely to want to
6058 change. As the scripts themselves are frequently
6059 <tt>conffile</tt>s, modifying them requires that the
6060 administrator merge in their changes each time the package
6061 is upgraded and the <tt>conffile</tt> changes. To ease
6062 the burden on the system administrator, such configurable
6063 values should not be placed directly in the script.
6064 Instead, they should be placed in a file in
6065 <file>/etc/default</file>, which typically will have the same
6066 base name as the <file>init.d</file> script. This extra file
6067 should be sourced by the script when the script runs. It
6068 must contain only variable settings and comments in SUSv3
6069 <prgn>sh</prgn> format. It may either be a
6070 <tt>conffile</tt> or a configuration file maintained by
6071 the package maintainer scripts. See <ref id="config-files">
6076 To ensure that vital configurable values are always
6077 available, the <file>init.d</file> script should set default
6078 values for each of the shell variables it uses, either
6079 before sourcing the <file>/etc/default/</file> file or
6080 afterwards using something like the <tt>:
6081 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6082 script must behave sensibly and not fail if the
6083 <file>/etc/default</file> file is deleted.
6087 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6088 as temporary filesystems<footnote>
6089 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6090 options in <file>/etc/default/rcS</file>.
6091 </footnote>, so the <file>init.d</file> scripts must handle this
6092 correctly. This will typically amount to creating any required
6093 subdirectories dynamically when the <file>init.d</file> script
6094 is run, rather than including them in the package and relying on
6095 <prgn>dpkg</prgn> to create them.
6100 <heading>Interfacing with the initscript system</heading>
6103 Maintainers should use the abstraction layer provided by
6104 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6105 programs to deal with initscripts in their packages'
6106 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6107 and <prgn>postrm</prgn>.
6111 Directly managing the /etc/rc?.d links and directly
6112 invoking the <file>/etc/init.d/</file> initscripts should
6113 be done only by packages providing the initscript
6114 subsystem (such as <prgn>sysv-rc</prgn> and
6115 <prgn>file-rc</prgn>).
6119 <heading>Managing the links</heading>
6122 The program <prgn>update-rc.d</prgn> is provided for
6123 package maintainers to arrange for the proper creation and
6124 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6125 or their functional equivalent if another method is being
6126 used. This may be used by maintainers in their packages'
6127 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6131 You must not include any <file>/etc/rc<var>n</var>.d</file>
6132 symbolic links in the actual archive or manually create or
6133 remove the symbolic links in maintainer scripts; you must
6134 use the <prgn>update-rc.d</prgn> program instead. (The
6135 former will fail if an alternative method of maintaining
6136 runlevel information is being used.) You must not include
6137 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6138 in the archive either. (Only the <tt>sysvinit</tt>
6143 By default <prgn>update-rc.d</prgn> will start services in
6144 each of the multi-user state runlevels (2, 3, 4, and 5)
6145 and stop them in the halt runlevel (0), the single-user
6146 runlevel (1) and the reboot runlevel (6). The system
6147 administrator will have the opportunity to customize
6148 runlevels by simply adding, moving, or removing the
6149 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6150 symbolic links are being used, or by modifying
6151 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6156 To get the default behavior for your package, put in your
6157 <prgn>postinst</prgn> script
6158 <example compact="compact">
6159 update-rc.d <var>package</var> defaults
6161 and in your <prgn>postrm</prgn>
6162 <example compact="compact">
6163 if [ "$1" = purge ]; then
6164 update-rc.d <var>package</var> remove
6166 </example>. Note that if your package changes runlevels
6167 or priority, you may have to remove and recreate the links,
6168 since otherwise the old links may persist. Refer to the
6169 documentation of <prgn>update-rc.d</prgn>.
6173 This will use a default sequence number of 20. If it does
6174 not matter when or in which order the <file>init.d</file>
6175 script is run, use this default. If it does, then you
6176 should talk to the maintainer of the <prgn>sysvinit</prgn>
6177 package or post to <tt>debian-devel</tt>, and they will
6178 help you choose a number.
6182 For more information about using <tt>update-rc.d</tt>,
6183 please consult its man page <manref name="update-rc.d"
6189 <heading>Running initscripts</heading>
6191 The program <prgn>invoke-rc.d</prgn> is provided to make
6192 it easier for package maintainers to properly invoke an
6193 initscript, obeying runlevel and other locally-defined
6194 constraints that might limit a package's right to start,
6195 stop and otherwise manage services. This program may be
6196 used by maintainers in their packages' scripts.
6200 The package maintainer scripts must use
6201 <prgn>invoke-rc.d</prgn> to invoke the
6202 <file>/etc/init.d/*</file> initscripts, instead of
6203 calling them directly.
6207 By default, <prgn>invoke-rc.d</prgn> will pass any
6208 action requests (start, stop, reload, restart...) to the
6209 <file>/etc/init.d</file> script, filtering out requests
6210 to start or restart a service out of its intended
6215 Most packages will simply need to change:
6216 <example compact="compact">/etc/init.d/<package>
6217 <action></example> in their <prgn>postinst</prgn>
6218 and <prgn>prerm</prgn> scripts to:
6219 <example compact="compact">
6220 if which invoke-rc.d >/dev/null 2>&1; then
6221 invoke-rc.d <var>package</var> <action>
6223 /etc/init.d/<var>package</var> <action>
6229 A package should register its initscript services using
6230 <prgn>update-rc.d</prgn> before it tries to invoke them
6231 using <prgn>invoke-rc.d</prgn>. Invocation of
6232 unregistered services may fail.
6236 For more information about using
6237 <prgn>invoke-rc.d</prgn>, please consult its man page
6238 <manref name="invoke-rc.d" section="8">.
6244 <heading>Boot-time initialization</heading>
6247 There used to be another directory, <file>/etc/rc.boot</file>,
6248 which contained scripts which were run once per machine
6249 boot. This has been deprecated in favour of links from
6250 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6251 described in <ref id="/etc/init.d">. Packages must not
6252 place files in <file>/etc/rc.boot</file>.
6257 <heading>Example</heading>
6260 An example on which you can base your
6261 <file>/etc/init.d</file> scripts is found in
6262 <file>/etc/init.d/skeleton</file>.
6269 <heading>Console messages from <file>init.d</file> scripts</heading>
6272 This section describes the formats to be used for messages
6273 written to standard output by the <file>/etc/init.d</file>
6274 scripts. The intent is to improve the consistency of
6275 Debian's startup and shutdown look and feel. For this
6276 reason, please look very carefully at the details. We want
6277 the messages to have the same format in terms of wording,
6278 spaces, punctuation and case of letters.
6282 Here is a list of overall rules that should be used for
6283 messages generated by <file>/etc/init.d</file> scripts.
6289 The message should fit in one line (fewer than 80
6290 characters), start with a capital letter and end with
6291 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6295 If the script is performing some time consuming task in
6296 the background (not merely starting or stopping a
6297 program, for instance), an ellipsis (three dots:
6298 <tt>...</tt>) should be output to the screen, with no
6299 leading or tailing whitespace or line feeds.
6303 The messages should appear as if the computer is telling
6304 the user what it is doing (politely :-), but should not
6305 mention "it" directly. For example, instead of:
6306 <example compact="compact">
6307 I'm starting network daemons: nfsd mountd.
6309 the message should say
6310 <example compact="compact">
6311 Starting network daemons: nfsd mountd.
6318 <tt>init.d</tt> script should use the following standard
6319 message formats for the situations enumerated below.
6325 <p>When daemons are started</p>
6328 If the script starts one or more daemons, the output
6329 should look like this (a single line, no leading
6331 <example compact="compact">
6332 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6334 The <var>description</var> should describe the
6335 subsystem the daemon or set of daemons are part of,
6336 while <var>daemon-1</var> up to <var>daemon-n</var>
6337 denote each daemon's name (typically the file name of
6342 For example, the output of <file>/etc/init.d/lpd</file>
6344 <example compact="compact">
6345 Starting printer spooler: lpd.
6350 This can be achieved by saying
6351 <example compact="compact">
6352 echo -n "Starting printer spooler: lpd"
6353 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6356 in the script. If there are more than one daemon to
6357 start, the output should look like this:
6358 <example compact="compact">
6359 echo -n "Starting remote file system services:"
6360 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6361 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6362 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6365 This makes it possible for the user to see what is
6366 happening and when the final daemon has been started.
6367 Care should be taken in the placement of white spaces:
6368 in the example above the system administrators can
6369 easily comment out a line if they don't want to start
6370 a specific daemon, while the displayed message still
6376 <p>When a system parameter is being set</p>
6379 If you have to set up different system parameters
6380 during the system boot, you should use this format:
6381 <example compact="compact">
6382 Setting <var>parameter</var> to "<var>value</var>".
6387 You can use a statement such as the following to get
6389 <example compact="compact">
6390 echo "Setting DNS domainname to \"$domainname\"."
6395 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6396 for the left and right quotation marks. A grave accent
6397 (<tt>`</tt>) is not a quote character; neither is an
6398 apostrophe (<tt>'</tt>).
6403 <p>When a daemon is stopped or restarted</p>
6406 When you stop or restart a daemon, you should issue a
6407 message identical to the startup message, except that
6408 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6409 or <tt>Restarting</tt> respectively.
6413 For example, stopping the printer daemon will look like
6415 <example compact="compact">
6416 Stopping printer spooler: lpd.
6422 <p>When something is executed</p>
6425 There are several examples where you have to run a
6426 program at system startup or shutdown to perform a
6427 specific task, for example, setting the system's clock
6428 using <prgn>netdate</prgn> or killing all processes
6429 when the system shuts down. Your message should look
6431 <example compact="compact">
6432 Doing something very useful...done.
6434 You should print the <tt>done.</tt> immediately after
6435 the job has been completed, so that the user is
6436 informed why they have to wait. You can get this
6438 <example compact="compact">
6439 echo -n "Doing something very useful..."
6448 <p>When the configuration is reloaded</p>
6451 When a daemon is forced to reload its configuration
6452 files you should use the following format:
6453 <example compact="compact">
6454 Reloading <var>description</var> configuration...done.
6456 where <var>description</var> is the same as in the
6457 daemon starting message.
6465 <heading>Cron jobs</heading>
6468 Packages must not modify the configuration file
6469 <file>/etc/crontab</file>, and they must not modify the files in
6470 <file>/var/spool/cron/crontabs</file>.</p>
6473 If a package wants to install a job that has to be executed
6474 via cron, it should place a file with the name of the
6475 package in one or more of the following directories:
6476 <example compact="compact">
6482 As these directory names imply, the files within them are
6483 executed on an hourly, daily, weekly, or monthly basis,
6484 respectively. The exact times are listed in
6485 <file>/etc/crontab</file>.</p>
6488 All files installed in any of these directories must be
6489 scripts (e.g., shell scripts or Perl scripts) so that they
6490 can easily be modified by the local system administrator.
6491 In addition, they must be treated as configuration files.
6495 If a certain job has to be executed at some other frequency or
6496 at a specific time, the package should install a file
6497 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6498 same syntax as <file>/etc/crontab</file> and is processed by
6499 <prgn>cron</prgn> automatically. The file must also be
6500 treated as a configuration file. (Note that entries in the
6501 <file>/etc/cron.d</file> directory are not handled by
6502 <prgn>anacron</prgn>. Thus, you should only use this
6503 directory for jobs which may be skipped if the system is not
6507 The scripts or crontab entries in these directories should
6508 check if all necessary programs are installed before they
6509 try to execute them. Otherwise, problems will arise when a
6510 package was removed but not purged since configuration files
6511 are kept on the system in this situation.</p>
6515 <heading>Menus</heading>
6518 The Debian <tt>menu</tt> package provides a standard
6519 interface between packages providing applications and
6520 <em>menu programs</em> (either X window managers or
6521 text-based menu programs such as <prgn>pdmenu</prgn>).
6525 All packages that provide applications that need not be
6526 passed any special command line arguments for normal
6527 operation should register a menu entry for those
6528 applications, so that users of the <tt>menu</tt> package
6529 will automatically get menu entries in their window
6530 managers, as well in shells like <tt>pdmenu</tt>.
6534 Menu entries should follow the current menu policy.
6538 The menu policy can be found in the <tt>menu-policy</tt>
6539 files in the <tt>debian-policy</tt> package.
6540 It is also available from the Debian web mirrors at
6541 <tt><url name="/doc/packaging-manuals/menu-policy/"
6542 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6546 Please also refer to the <em>Debian Menu System</em>
6547 documentation that comes with the <package>menu</package>
6548 package for information about how to register your
6554 <heading>Multimedia handlers</heading>
6557 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6558 is a mechanism for encoding files and data streams and
6559 providing meta-information about them, in particular their
6560 type (e.g. audio or video) and format (e.g. PNG, HTML,
6565 Registration of MIME type handlers allows programs like mail
6566 user agents and web browsers to invoke these handlers to
6567 view, edit or display MIME types they don't support directly.
6571 Packages which provide the ability to view/show/play,
6572 compose, edit or print MIME types should register themselves
6573 as such following the current MIME support policy.
6577 The MIME support policy can be found in the <tt>mime-policy</tt>
6578 files in the <tt>debian-policy</tt> package.
6579 It is also available from the Debian web mirrors at
6580 <tt><url name="/doc/packaging-manuals/mime-policy/"
6581 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6587 <heading>Keyboard configuration</heading>
6590 To achieve a consistent keyboard configuration so that all
6591 applications interpret a keyboard event the same way, all
6592 programs in the Debian distribution must be configured to
6593 comply with the following guidelines.
6597 The following keys must have the specified interpretations:
6600 <tag><tt><--</tt></tag>
6601 <item>delete the character to the left of the cursor</item>
6603 <tag><tt>Delete</tt></tag>
6604 <item>delete the character to the right of the cursor</item>
6606 <tag><tt>Control+H</tt></tag>
6607 <item>emacs: the help prefix</item>
6610 The interpretation of any keyboard events should be
6611 independent of the terminal that is used, be it a virtual
6612 console, an X terminal emulator, an rlogin/telnet session,
6617 The following list explains how the different programs
6618 should be set up to achieve this:
6624 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6628 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6632 X translations are set up to make
6633 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6634 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6635 is the vt220 escape code for the "delete character"
6636 key). This must be done by loading the X resources
6637 using <prgn>xrdb</prgn> on all local X displays, not
6638 using the application defaults, so that the
6639 translation resources used correspond to the
6640 <prgn>xmodmap</prgn> settings.
6644 The Linux console is configured to make
6645 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6646 generate <tt>ESC [ 3 ~</tt>.
6650 X applications are configured so that <tt><</tt>
6651 deletes left, and <tt>Delete</tt> deletes right. Motif
6652 applications already work like this.
6656 Terminals should have <tt>stty erase ^?</tt> .
6660 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6661 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6662 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6666 Emacs is programmed to map <tt>KB_Backspace</tt> or
6667 the <tt>stty erase</tt> character to
6668 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6669 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6670 <tt>^H</tt> to <tt>help</tt> as always.
6674 Other applications use the <tt>stty erase</tt>
6675 character and <tt>kdch1</tt> for the two delete keys,
6676 with ASCII DEL being "delete previous character" and
6677 <tt>kdch1</tt> being "delete character under
6685 This will solve the problem except for the following
6692 Some terminals have a <tt><--</tt> key that cannot
6693 be made to produce anything except <tt>^H</tt>. On
6694 these terminals Emacs help will be unavailable on
6695 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6696 character takes precedence in Emacs, and has been set
6697 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6698 available) can be used instead.
6702 Some operating systems use <tt>^H</tt> for <tt>stty
6703 erase</tt>. However, modern telnet versions and all
6704 rlogin versions propagate <tt>stty</tt> settings, and
6705 almost all UNIX versions honour <tt>stty erase</tt>.
6706 Where the <tt>stty</tt> settings are not propagated
6707 correctly, things can be made to work by using
6708 <tt>stty</tt> manually.
6712 Some systems (including previous Debian versions) use
6713 <prgn>xmodmap</prgn> to arrange for both
6714 <tt><--</tt> and <tt>Delete</tt> to generate
6715 <tt>KB_Delete</tt>. We can change the behavior of
6716 their X clients using the same X resources that we use
6717 to do it for our own clients, or configure our clients
6718 using their resources when things are the other way
6719 around. On displays configured like this
6720 <tt>Delete</tt> will not work, but <tt><--</tt>
6725 Some operating systems have different <tt>kdch1</tt>
6726 settings in their <tt>terminfo</tt> database for
6727 <tt>xterm</tt> and others. On these systems the
6728 <tt>Delete</tt> key will not work correctly when you
6729 log in from a system conforming to our policy, but
6730 <tt><--</tt> will.
6737 <heading>Environment variables</heading>
6740 A program must not depend on environment variables to get
6741 reasonable defaults. (That's because these environment
6742 variables would have to be set in a system-wide
6743 configuration file like <file>/etc/profile</file>, which is not
6744 supported by all shells.)
6748 If a program usually depends on environment variables for its
6749 configuration, the program should be changed to fall back to
6750 a reasonable default configuration if these environment
6751 variables are not present. If this cannot be done easily
6752 (e.g., if the source code of a non-free program is not
6753 available), the program must be replaced by a small
6754 "wrapper" shell script which sets the environment variables
6755 if they are not already defined, and calls the original program.
6759 Here is an example of a wrapper script for this purpose:
6761 <example compact="compact">
6763 BAR=${BAR:-/var/lib/fubar}
6765 exec /usr/lib/foo/foo "$@"
6770 Furthermore, as <file>/etc/profile</file> is a configuration
6771 file of the <prgn>base-files</prgn> package, other packages must
6772 not put any environment variables or other commands into that
6777 <sect id="doc-base">
6778 <heading>Registering Documents using doc-base</heading>
6781 The <package>doc-base</package> package implements a
6782 flexible mechanism for handling and presenting
6783 documentation. The recommended practice is for every Debian
6784 package that provides online documentation (other than just
6785 manual pages) to register these documents with
6786 <package>doc-base</package> by installing a
6787 <package>doc-base</package> control file via the
6788 <prgn/install-docs/ script at installation time and
6789 de-register the manuals again when the package is removed.
6792 Please refer to the documentation that comes with the
6793 <package>doc-base</package> package for information and
6802 <heading>Files</heading>
6805 <heading>Binaries</heading>
6808 Two different packages must not install programs with
6809 different functionality but with the same filenames. (The
6810 case of two programs having the same functionality but
6811 different implementations is handled via "alternatives" or
6812 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6813 <ref id="conflicts"> respectively.) If this case happens,
6814 one of the programs must be renamed. The maintainers should
6815 report this to the <tt>debian-devel</tt> mailing list and
6816 try to find a consensus about which program will have to be
6817 renamed. If a consensus cannot be reached, <em>both</em>
6818 programs must be renamed.
6822 By default, when a package is being built, any binaries
6823 created should include debugging information, as well as
6824 being compiled with optimization. You should also turn on
6825 as many reasonable compilation warnings as possible; this
6826 makes life easier for porters, who can then look at build
6827 logs for possible problems. For the C programming language,
6828 this means the following compilation parameters should be
6830 <example compact="compact">
6832 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6834 INSTALL = install -s # (or use strip on the files in debian/tmp)
6839 Note that by default all installed binaries should be stripped,
6840 either by using the <tt>-s</tt> flag to
6841 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6842 the binaries after they have been copied into
6843 <file>debian/tmp</file> but before the tree is made into a
6848 Although binaries in the build tree should be compiled with
6849 debugging information by default, it can often be difficult to
6850 debug programs if they are also subjected to compiler
6851 optimization. For this reason, it is recommended to support the
6852 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6853 (see <ref id="debianrules-options">). This variable can contain
6854 several flags to change how a package is compiled and built.
6858 It is up to the package maintainer to decide what
6859 compilation options are best for the package. Certain
6860 binaries (such as computationally-intensive programs) will
6861 function better with certain flags (<tt>-O3</tt>, for
6862 example); feel free to use them. Please use good judgment
6863 here. Don't use flags for the sake of it; only use them
6864 if there is good reason to do so. Feel free to override
6865 the upstream author's ideas about which compilation
6866 options are best: they are often inappropriate for our
6872 <sect id="libraries">
6873 <heading>Libraries</heading>
6876 If the package is <strong>architecture: any</strong>, then
6877 the shared library compilation and linking flags must have
6878 <tt>-fPIC</tt>, or the package shall not build on some of
6879 the supported architectures<footnote>
6881 If you are using GCC, <tt>-fPIC</tt> produces code with
6882 relocatable position independent code, which is required for
6883 most architectures to create a shared library, with i386 and
6884 perhaps some others where non position independent code is
6885 permitted in a shared library.
6888 Position independent code may have a performance penalty,
6889 especially on <tt>i386</tt>. However, in most cases the
6890 speed penalty must be measured against the memory wasted on
6891 the few architectures where non position independent code is
6894 </footnote>. Any exception to this rule must be discussed on
6895 the mailing list <em>debian-devel@lists.debian.org</em>, and
6896 a rough consensus obtained. The reasons for not compiling
6897 with <tt>-fPIC</tt> flag must be recorded in the file
6898 <tt>README.Debian</tt>, and care must be taken to either
6899 restrict the architecture or arrange for <tt>-fPIC</tt> to
6900 be used on architectures where it is required.<footnote>
6902 Some of the reasons why this might be required is if the
6903 library contains hand crafted assembly code that is not
6904 relocatable, the speed penalty is excessive for compute
6905 intensive libs, and similar reasons.
6910 As to the static libraries, the common case is not to have
6911 relocatable code, since there is no benefit, unless in specific
6912 cases; therefore the static version must not be compiled
6913 with the <tt>-fPIC</tt> flag. Any exception to this rule
6914 should be discussed on the mailing list
6915 <em>debian-devel@lists.debian.org</em>, and the reasons for
6916 compiling with the <tt>-fPIC</tt> flag must be recorded in
6917 the file <tt>README.Debian</tt>. <footnote>
6919 Some of the reasons for linking static libraries with
6920 the <tt>-fPIC</tt> flag are if, for example, one needs a
6921 Perl API for a library that is under rapid development,
6922 and has an unstable API, so shared libraries are
6923 pointless at this phase of the library's development. In
6924 that case, since Perl needs a library with relocatable
6925 code, it may make sense to create a static library with
6926 relocatable code. Another reason cited is if you are
6927 distilling various libraries into a common shared
6928 library, like <tt>mklibs</tt> does in the Debian
6934 In other words, if both a shared and a static library is
6935 being built, each source unit (<tt>*.c</tt>, for example,
6936 for C files) will need to be compiled twice, for the normal
6940 You must specify the gcc option <tt>-D_REENTRANT</tt>
6941 when building a library (either static or shared) to make
6942 the library compatible with LinuxThreads.
6946 Although not enforced by the build tools, shared libraries
6947 must be linked against all libraries that they use symbols from
6948 in the same way that binaries are. This ensures the correct
6949 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6950 system and guarantees that all libraries can be safely opened
6951 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6952 option <tt>-Wl,-z,defs</tt> when building a shared library.
6953 Since this option enforces symbol resolution at build time,
6954 a missing library reference will be caught early as a fatal
6959 All installed shared libraries should be stripped with
6960 <example compact="compact">
6961 strip --strip-unneeded <var>your-lib</var>
6963 (The option <tt>--strip-unneeded</tt> makes
6964 <prgn>strip</prgn> remove only the symbols which aren't
6965 needed for relocation processing.) Shared libraries can
6966 function perfectly well when stripped, since the symbols for
6967 dynamic linking are in a separate part of the ELF object
6969 You might also want to use the options
6970 <tt>--remove-section=.comment</tt> and
6971 <tt>--remove-section=.note</tt> on both shared libraries
6972 and executables, and <tt>--strip-debug</tt> on static
6978 Note that under some circumstances it may be useful to
6979 install a shared library unstripped, for example when
6980 building a separate package to support debugging.
6984 Shared object files (often <file>.so</file> files) that are not
6985 public libraries, that is, they are not meant to be linked
6986 to by third party executables (binaries of other packages),
6987 should be installed in subdirectories of the
6988 <file>/usr/lib</file> directory. Such files are exempt from the
6989 rules that govern ordinary shared libraries, except that
6990 they must not be installed executable and should be
6992 A common example are the so-called "plug-ins",
6993 internal shared objects that are dynamically loaded by
6994 programs using <manref name="dlopen" section="3">.
6999 An ever increasing number of packages are using
7000 <prgn>libtool</prgn> to do their linking. The latest GNU
7001 libtools (>= 1.3a) can take advantage of the metadata in the
7002 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7003 files). The main advantage of <prgn>libtool</prgn>'s
7004 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7005 store and subsequently access metadata with respect to the
7006 libraries it builds. <prgn>libtool</prgn> will search for
7007 those files, which contain a lot of useful information about
7008 a library (such as library dependency information for static
7009 linking). Also, they're <em>essential</em> for programs
7010 using <tt>libltdl</tt>.<footnote>
7011 Although <prgn>libtool</prgn> is fully capable of
7012 linking against shared libraries which don't have
7013 <tt>.la</tt> files, as it is a mere shell script it can
7014 add considerably to the build time of a
7015 <prgn>libtool</prgn>-using package if that shell script
7016 has to derive all this information from first principles
7017 for each library every time it is linked. With the
7018 advent of <prgn>libtool</prgn> version 1.4 (and to a
7019 lesser extent <prgn>libtool</prgn> version 1.3), the
7020 <file>.la</file> files also store information about
7021 inter-library dependencies which cannot necessarily be
7022 derived after the <file>.la</file> file is deleted.
7027 Packages that use <prgn>libtool</prgn> to create shared
7028 libraries should include the <file>.la</file> files in the
7029 <tt>-dev</tt> package, unless the package relies on
7030 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7031 the <tt>.la</tt> files must go in the run-time library
7036 You must make sure that you use only released versions of
7037 shared libraries to build your packages; otherwise other
7038 users will not be able to run your binaries
7039 properly. Producing source packages that depend on
7040 unreleased compilers is also usually a bad
7047 <heading>Shared libraries</heading>
7049 This section has moved to <ref id="sharedlibs">.
7055 <heading>Scripts</heading>
7058 All command scripts, including the package maintainer
7059 scripts inside the package and used by <prgn>dpkg</prgn>,
7060 should have a <tt>#!</tt> line naming the shell to be used
7065 In the case of Perl scripts this should be
7066 <tt>#!/usr/bin/perl</tt>.
7070 When scripts are installed into a directory in the system
7071 PATH, the script name should not include an extension such
7072 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7073 language currently used to implement it.
7076 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7077 should almost certainly start with <tt>set -e</tt> so that
7078 errors are detected. Every script should use
7079 <tt>set -e</tt> or check the exit status of <em>every</em>
7084 Scripts may assume that <file>/bin/sh</file> implements the
7085 SUSv3 Shell Command Language<footnote>
7086 Single UNIX Specification, version 3, which is also IEEE
7087 1003.1-2004 (POSIX), and is available on the World Wide Web
7088 from <url id="http://www.unix.org/version3/online.html"
7089 name="The Open Group"> after free
7090 registration.</footnote>
7091 plus the following additional features not mandated by
7093 These features are in widespread use in the Linux community
7094 and are implemented in all of bash, dash, and ksh, the most
7095 common shells users may wish to use as <file>/bin/sh</file>.
7098 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7099 must not generate a newline.</item>
7100 <item><tt>test</tt>, if implemented as a shell built-in, must
7101 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7103 <item><tt>local</tt> to create a scoped variable must be
7104 supported, including listing multiple variables in a single
7105 local command and assigning a value to a variable at the
7106 same time as localizing it. <tt>local</tt> may or
7107 may not preserve the variable value from an outer scope if
7108 no assignment is present. Uses such as:
7112 # ... use a, b, c, d ...
7115 must be supported and must set the value of <tt>c</tt> to
7119 If a shell script requires non-SUSv3 features from the shell
7120 interpreter other than those listed above, the appropriate shell
7121 must be specified in the first line of the script (e.g.,
7122 <tt>#!/bin/bash</tt>) and the package must depend on the package
7123 providing the shell (unless the shell package is marked
7124 "Essential", as in the case of <prgn>bash</prgn>).
7128 You may wish to restrict your script to SUSv3 features plus the
7129 above set when possible so that it may use <file>/bin/sh</file>
7130 as its interpreter. If your script works with <prgn>dash</prgn>
7131 (originally called <prgn>ash</prgn>), it probably complies with
7132 the above requirements, but if you are in doubt, use
7133 <file>/bin/bash</file>.
7137 Perl scripts should check for errors when making any
7138 system calls, including <tt>open</tt>, <tt>print</tt>,
7139 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7143 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7144 scripting languages. See <em>Csh Programming Considered
7145 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7146 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7147 If an upstream package comes with <prgn>csh</prgn> scripts
7148 then you must make sure that they start with
7149 <tt>#!/bin/csh</tt> and make your package depend on the
7150 <prgn>c-shell</prgn> virtual package.
7154 Any scripts which create files in world-writeable
7155 directories (e.g., in <file>/tmp</file>) must use a
7156 mechanism which will fail atomically if a file with the same
7157 name already exists.
7161 The Debian base system provides the <prgn>tempfile</prgn>
7162 and <prgn>mktemp</prgn> utilities for use by scripts for
7169 <heading>Symbolic links</heading>
7172 In general, symbolic links within a top-level directory
7173 should be relative, and symbolic links pointing from one
7174 top-level directory into another should be absolute. (A
7175 top-level directory is a sub-directory of the root
7176 directory <file>/</file>.)
7180 In addition, symbolic links should be specified as short as
7181 possible, i.e., link targets like <file>foo/../bar</file> are
7186 Note that when creating a relative link using
7187 <prgn>ln</prgn> it is not necessary for the target of the
7188 link to exist relative to the working directory you're
7189 running <prgn>ln</prgn> from, nor is it necessary to change
7190 directory to the directory where the link is to be made.
7191 Simply include the string that should appear as the target
7192 of the link (this will be a pathname relative to the
7193 directory in which the link resides) as the first argument
7198 For example, in your <prgn>Makefile</prgn> or
7199 <file>debian/rules</file>, you can do things like:
7200 <example compact="compact">
7201 ln -fs gcc $(prefix)/bin/cc
7202 ln -fs gcc debian/tmp/usr/bin/cc
7203 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7204 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7209 A symbolic link pointing to a compressed file should always
7210 have the same file extension as the referenced file. (For
7211 example, if a file <file>foo.gz</file> is referenced by a
7212 symbolic link, the filename of the link has to end with
7213 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7218 <heading>Device files</heading>
7221 Packages must not include device files in the package file
7226 If a package needs any special device files that are not
7227 included in the base system, it must call
7228 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7229 after notifying the user<footnote>
7230 This notification could be done via a (low-priority)
7231 debconf message, or an echo (printf) statement.
7236 Packages must not remove any device files in the
7237 <prgn>postrm</prgn> or any other script. This is left to the
7238 system administrator.
7242 Debian uses the serial devices
7243 <file>/dev/ttyS*</file>. Programs using the old
7244 <file>/dev/cu*</file> devices should be changed to use
7245 <file>/dev/ttyS*</file>.
7249 <sect id="config-files">
7250 <heading>Configuration files</heading>
7253 <heading>Definitions</heading>
7257 <tag>configuration file</tag>
7259 A file that affects the operation of a program, or
7260 provides site- or host-specific information, or
7261 otherwise customizes the behavior of a program.
7262 Typically, configuration files are intended to be
7263 modified by the system administrator (if needed or
7264 desired) to conform to local policy or to provide
7265 more useful site-specific behavior.
7268 <tag><tt>conffile</tt></tag>
7270 A file listed in a package's <tt>conffiles</tt>
7271 file, and is treated specially by <prgn>dpkg</prgn>
7272 (see <ref id="configdetails">).
7278 The distinction between these two is important; they are
7279 not interchangeable concepts. Almost all
7280 <tt>conffile</tt>s are configuration files, but many
7281 configuration files are not <tt>conffiles</tt>.
7285 As noted elsewhere, <file>/etc/init.d</file> scripts,
7286 <file>/etc/default</file> files, scripts installed in
7287 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7288 configuration installed in <file>/etc/cron.d</file> must be
7289 treated as configuration files. In general, any script that
7290 embeds configuration information is de-facto a configuration
7291 file and should be treated as such.
7296 <heading>Location</heading>
7299 Any configuration files created or used by your package
7300 must reside in <file>/etc</file>. If there are several,
7301 consider creating a subdirectory of <file>/etc</file>
7302 named after your package.
7306 If your package creates or uses configuration files
7307 outside of <file>/etc</file>, and it is not feasible to modify
7308 the package to use <file>/etc</file> directly, put the files
7309 in <file>/etc</file> and create symbolic links to those files
7310 from the location that the package requires.
7315 <heading>Behavior</heading>
7318 Configuration file handling must conform to the following
7320 <list compact="compact">
7322 local changes must be preserved during a package
7326 configuration files must be preserved when the
7327 package is removed, and only deleted when the
7334 The easy way to achieve this behavior is to make the
7335 configuration file a <tt>conffile</tt>. This is
7336 appropriate only if it is possible to distribute a default
7337 version that will work for most installations, although
7338 some system administrators may choose to modify it. This
7339 implies that the default version will be part of the
7340 package distribution, and must not be modified by the
7341 maintainer scripts during installation (or at any other
7346 In order to ensure that local changes are preserved
7347 correctly, no package may contain or make hard links to
7348 conffiles.<footnote>
7349 Rationale: There are two problems with hard links.
7350 The first is that some editors break the link while
7351 editing one of the files, so that the two files may
7352 unwittingly become unlinked and different. The second
7353 is that <prgn>dpkg</prgn> might break the hard link
7354 while upgrading <tt>conffile</tt>s.
7359 The other way to do it is via the maintainer scripts. In
7360 this case, the configuration file must not be listed as a
7361 <tt>conffile</tt> and must not be part of the package
7362 distribution. If the existence of a file is required for
7363 the package to be sensibly configured it is the
7364 responsibility of the package maintainer to provide
7365 maintainer scripts which correctly create, update and
7366 maintain the file and remove it on purge. (See <ref
7367 id="maintainerscripts"> for more information.) These
7368 scripts must be idempotent (i.e., must work correctly if
7369 <prgn>dpkg</prgn> needs to re-run them due to errors
7370 during installation or removal), must cope with all the
7371 variety of ways <prgn>dpkg</prgn> can call maintainer
7372 scripts, must not overwrite or otherwise mangle the user's
7373 configuration without asking, must not ask unnecessary
7374 questions (particularly during upgrades), and must
7375 otherwise be good citizens.
7379 The scripts are not required to configure every possible
7380 option for the package, but only those necessary to get
7381 the package running on a given system. Ideally the
7382 sysadmin should not have to do any configuration other
7383 than that done (semi-)automatically by the
7384 <prgn>postinst</prgn> script.
7388 A common practice is to create a script called
7389 <file><var>package</var>-configure</file> and have the
7390 package's <prgn>postinst</prgn> call it if and only if the
7391 configuration file does not already exist. In certain
7392 cases it is useful for there to be an example or template
7393 file which the maintainer scripts use. Such files should
7394 be in <file>/usr/share/<var>package</var></file> or
7395 <file>/usr/lib/<var>package</var></file> (depending on whether
7396 they are architecture-independent or not). There should
7397 be symbolic links to them from
7398 <file>/usr/share/doc/<var>package</var>/examples</file> if
7399 they are examples, and should be perfectly ordinary
7400 <prgn>dpkg</prgn>-handled files (<em>not</em>
7401 configuration files).
7405 These two styles of configuration file handling must
7406 not be mixed, for that way lies madness:
7407 <prgn>dpkg</prgn> will ask about overwriting the file
7408 every time the package is upgraded.
7413 <heading>Sharing configuration files</heading>
7416 Packages which specify the same file as a
7417 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7418 with each other. (This is an instance of the general rule
7419 about not sharing files. Note that neither alternatives
7420 nor diversions are likely to be appropriate in this case;
7421 in particular, <prgn>dpkg</prgn> does not handle diverted
7422 <tt>conffile</tt>s well.)
7426 The maintainer scripts must not alter a <tt>conffile</tt>
7427 of <em>any</em> package, including the one the scripts
7432 If two or more packages use the same configuration file
7433 and it is reasonable for both to be installed at the same
7434 time, one of these packages must be defined as
7435 <em>owner</em> of the configuration file, i.e., it will be
7436 the package which handles that file as a configuration
7437 file. Other packages that use the configuration file must
7438 depend on the owning package if they require the
7439 configuration file to operate. If the other package will
7440 use the configuration file if present, but is capable of
7441 operating without it, no dependency need be declared.
7445 If it is desirable for two or more related packages to
7446 share a configuration file <em>and</em> for all of the
7447 related packages to be able to modify that configuration
7448 file, then the following should be done:
7449 <enumlist compact="compact">
7451 One of the related packages (the "owning" package)
7452 will manage the configuration file with maintainer
7453 scripts as described in the previous section.
7456 The owning package should also provide a program
7457 that the other packages may use to modify the
7461 The related packages must use the provided program
7462 to make any desired modifications to the
7463 configuration file. They should either depend on
7464 the core package to guarantee that the configuration
7465 modifier program is available or accept gracefully
7466 that they cannot modify the configuration file if it
7467 is not. (This is in addition to the fact that the
7468 configuration file may not even be present in the
7475 Sometimes it's appropriate to create a new package which
7476 provides the basic infrastructure for the other packages
7477 and which manages the shared configuration files. (The
7478 <tt>sgml-base</tt> package is a good example.)
7483 <heading>User configuration files ("dotfiles")</heading>
7486 The files in <file>/etc/skel</file> will automatically be
7487 copied into new user accounts by <prgn>adduser</prgn>.
7488 No other program should reference the files in
7489 <file>/etc/skel</file>.
7493 Therefore, if a program needs a dotfile to exist in
7494 advance in <file>$HOME</file> to work sensibly, that dotfile
7495 should be installed in <file>/etc/skel</file> and treated as a
7500 However, programs that require dotfiles in order to
7501 operate sensibly are a bad thing, unless they do create
7502 the dotfiles themselves automatically.
7506 Furthermore, programs should be configured by the Debian
7507 default installation to behave as closely to the upstream
7508 default behavior as possible.
7512 Therefore, if a program in a Debian package needs to be
7513 configured in some way in order to operate sensibly, that
7514 should be done using a site-wide configuration file placed
7515 in <file>/etc</file>. Only if the program doesn't support a
7516 site-wide default configuration and the package maintainer
7517 doesn't have time to add it may a default per-user file be
7518 placed in <file>/etc/skel</file>.
7522 <file>/etc/skel</file> should be as empty as we can make it.
7523 This is particularly true because there is no easy (or
7524 necessarily desirable) mechanism for ensuring that the
7525 appropriate dotfiles are copied into the accounts of
7526 existing users when a package is installed.
7532 <heading>Log files</heading>
7534 Log files should usually be named
7535 <file>/var/log/<var>package</var>.log</file>. If you have many
7536 log files, or need a separate directory for permission
7537 reasons (<file>/var/log</file> is writable only by
7538 <file>root</file>), you should usually create a directory named
7539 <file>/var/log/<var>package</var></file> and place your log
7544 Log files must be rotated occasionally so that they don't
7545 grow indefinitely; the best way to do this is to drop a log
7546 rotation configuration file into the directory
7547 <file>/etc/logrotate.d</file> and use the facilities provided by
7548 logrotate.<footnote>
7550 The traditional approach to log files has been to set up
7551 <em>ad hoc</em> log rotation schemes using simple shell
7552 scripts and cron. While this approach is highly
7553 customizable, it requires quite a lot of sysadmin work.
7554 Even though the original Debian system helped a little
7555 by automatically installing a system which can be used
7556 as a template, this was deemed not enough.
7560 The use of <prgn>logrotate</prgn>, a program developed
7561 by Red Hat, is better, as it centralizes log management.
7562 It has both a configuration file
7563 (<file>/etc/logrotate.conf</file>) and a directory where
7564 packages can drop their individual log rotation
7565 configurations (<file>/etc/logrotate.d</file>).
7568 Here is a good example for a logrotate config
7569 file (for more information see <manref name="logrotate"
7571 <example compact="compact">
7572 /var/log/foo/*.log {
7577 /etc/init.d/foo force-reload
7581 This rotates all files under <file>/var/log/foo</file>, saves 12
7582 compressed generations, and forces the daemon to reload its
7583 configuration information after the log rotation.
7587 Log files should be removed when the package is
7588 purged (but not when it is only removed). This should be
7589 done by the <prgn>postrm</prgn> script when it is called
7590 with the argument <tt>purge</tt> (see <ref
7591 id="removedetails">).
7596 <heading>Permissions and owners</heading>
7599 The rules in this section are guidelines for general use.
7600 If necessary you may deviate from the details below.
7601 However, if you do so you must make sure that what is done
7602 is secure and you should try to be as consistent as possible
7603 with the rest of the system. You should probably also
7604 discuss it on <prgn>debian-devel</prgn> first.
7608 Files should be owned by <tt>root:root</tt>, and made
7609 writable only by the owner and universally readable (and
7610 executable, if appropriate), that is mode 644 or 755.
7614 Directories should be mode 755 or (for group-writability)
7615 mode 2775. The ownership of the directory should be
7616 consistent with its mode: if a directory is mode 2775, it
7617 should be owned by the group that needs write access to
7620 When a package is upgraded, and the owner or permissions
7621 of a file included in the package has changed, dpkg
7622 arranges for the ownership and permissions to be
7623 correctly set upon installation. However, this does not
7624 extend to directories; the permissions and ownership of
7625 directories already on the system does not change on
7626 install or upgrade of packages. This makes sense, since
7627 otherwise common directories like <tt>/usr</tt> would
7628 always be in flux. To correctly change permissions of a
7629 directory the package owns, explicit action is required,
7630 usually in the <tt>postinst</tt> script. Care must be
7631 taken to handle downgrades as well, in that case.
7638 Setuid and setgid executables should be mode 4755 or 2755
7639 respectively, and owned by the appropriate user or group.
7640 They should not be made unreadable (modes like 4711 or
7641 2711 or even 4111); doing so achieves no extra security,
7642 because anyone can find the binary in the freely available
7643 Debian package; it is merely inconvenient. For the same
7644 reason you should not restrict read or execute permissions
7645 on non-set-id executables.
7649 Some setuid programs need to be restricted to particular
7650 sets of users, using file permissions. In this case they
7651 should be owned by the uid to which they are set-id, and by
7652 the group which should be allowed to execute them. They
7653 should have mode 4754; again there is no point in making
7654 them unreadable to those users who must not be allowed to
7659 It is possible to arrange that the system administrator can
7660 reconfigure the package to correspond to their local
7661 security policy by changing the permissions on a binary:
7662 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7663 described below.<footnote>
7664 Ordinary files installed by <prgn>dpkg</prgn> (as
7665 opposed to <tt>conffile</tt>s and other similar objects)
7666 normally have their permissions reset to the distributed
7667 permissions when the package is reinstalled. However,
7668 the use of <prgn>dpkg-statoverride</prgn> overrides this
7669 default behavior. If you use this method, you should
7670 remember to describe <prgn>dpkg-statoverride</prgn> in
7671 the package documentation; being a relatively new
7672 addition to Debian, it is probably not yet well-known.
7674 Another method you should consider is to create a group for
7675 people allowed to use the program(s) and make any setuid
7676 executables executable only by that group.
7680 If you need to create a new user or group for your package
7681 there are two possibilities. Firstly, you may need to
7682 make some files in the binary package be owned by this
7683 user or group, or you may need to compile the user or
7684 group id (rather than just the name) into the binary
7685 (though this latter should be avoided if possible, as in
7686 this case you need a statically allocated id).</p>
7689 If you need a statically allocated id, you must ask for a
7690 user or group id from the <tt>base-passwd</tt> maintainer,
7691 and must not release the package until you have been
7692 allocated one. Once you have been allocated one you must
7693 either make the package depend on a version of the
7694 <tt>base-passwd</tt> package with the id present in
7695 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7696 your package to create the user or group itself with the
7697 correct id (using <tt>adduser</tt>) in its
7698 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7699 the <prgn>postinst</prgn> is to be preferred if it is
7700 possible, otherwise a pre-dependency will be needed on the
7701 <tt>adduser</tt> package.)
7705 On the other hand, the program might be able to determine
7706 the uid or gid from the user or group name at runtime, so
7707 that a dynamically allocated id can be used. In this case
7708 you should choose an appropriate user or group name,
7709 discussing this on <prgn>debian-devel</prgn> and checking
7710 with the <package/base-passwd/ maintainer that it is unique and that
7711 they do not wish you to use a statically allocated id
7712 instead. When this has been checked you must arrange for
7713 your package to create the user or group if necessary using
7714 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7715 <prgn>postinst</prgn> script (again, the latter is to be
7716 preferred if it is possible).
7720 Note that changing the numeric value of an id associated
7721 with a name is very difficult, and involves searching the
7722 file system for all appropriate files. You need to think
7723 carefully whether a static or dynamic id is required, since
7724 changing your mind later will cause problems.
7727 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7729 This section is not intended as policy, but as a
7730 description of the use of <prgn>dpkg-statoverride</prgn>.
7734 If a system administrator wishes to have a file (or
7735 directory or other such thing) installed with owner and
7736 permissions different from those in the distributed Debian
7737 package, they can use the <prgn>dpkg-statoverride</prgn>
7738 program to instruct <prgn>dpkg</prgn> to use the different
7739 settings every time the file is installed. Thus the
7740 package maintainer should distribute the files with their
7741 normal permissions, and leave it for the system
7742 administrator to make any desired changes. For example, a
7743 daemon which is normally required to be setuid root, but
7744 in certain situations could be used without being setuid,
7745 should be installed setuid in the <tt>.deb</tt>. Then the
7746 local system administrator can change this if they wish.
7747 If there are two standard ways of doing it, the package
7748 maintainer can use <tt>debconf</tt> to find out the
7749 preference, and call <prgn>dpkg-statoverride</prgn> in the
7750 maintainer script if necessary to accommodate the system
7751 administrator's choice. Care must be taken during
7752 upgrades to not override an existing setting.
7756 Given the above, <prgn>dpkg-statoverride</prgn> is
7757 essentially a tool for system administrators and would not
7758 normally be needed in the maintainer scripts. There is
7759 one type of situation, though, where calls to
7760 <prgn>dpkg-statoverride</prgn> would be needed in the
7761 maintainer scripts, and that involves packages which use
7762 dynamically allocated user or group ids. In such a
7763 situation, something like the following idiom can be very
7764 helpful in the package's <prgn>postinst</prgn>, where
7765 <tt>sysuser</tt> is a dynamically allocated id:
7767 for i in /usr/bin/foo /usr/sbin/bar
7769 # only do something when no setting exists
7770 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7772 #include: debconf processing, question about foo and bar
7773 if [ "$RET" = "true" ] ; then
7774 dpkg-statoverride --update --add sysuser root 4755 $i
7779 The corresponding code to remove the override when the package
7782 for i in /usr/bin/foo /usr/sbin/bar
7784 if dpkg-statoverride --list $i >/dev/null 2>&1
7786 dpkg-statoverride --remove $i
7796 <chapt id="customized-programs">
7797 <heading>Customized programs</heading>
7799 <sect id="arch-spec">
7800 <heading>Architecture specification strings</heading>
7803 If a program needs to specify an <em>architecture specification
7804 string</em> in some place, it should select one of the
7805 strings provided by <tt>dpkg-architecture -L</tt>. The
7806 strings are in the format
7807 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7808 is sometimes elided, as when the OS is Linux.<footnote>
7809 <p>Currently, the strings are:
7810 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7811 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7812 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7813 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7814 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7815 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7816 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7817 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7818 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7819 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7820 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7821 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7822 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7823 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7824 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7825 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7826 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7827 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7828 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7829 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7830 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7831 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7832 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7833 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7834 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7835 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7836 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7837 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7838 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7839 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7840 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7841 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7842 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7843 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7844 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7845 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7846 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7852 Note that we don't want to use
7853 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7854 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7855 since this would make our programs incompatible with other
7856 Linux distributions. We also don't use something like
7857 <tt><var>arch</var>-unknown-linux</tt>, since the
7858 <tt>unknown</tt> does not look very good.
7863 <heading>Daemons</heading>
7866 The configuration files <file>/etc/services</file>,
7867 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7868 by the <prgn>netbase</prgn> package and must not be modified
7873 If a package requires a new entry in one of these files, the
7874 maintainer should get in contact with the
7875 <prgn>netbase</prgn> maintainer, who will add the entries
7876 and release a new version of the <prgn>netbase</prgn>
7881 The configuration file <file>/etc/inetd.conf</file> must not be
7882 modified by the package's scripts except via the
7883 <prgn>update-inetd</prgn> script or the
7884 <file>DebianNet.pm</file> Perl module. See their documentation
7885 for details on how to add entries.
7889 If a package wants to install an example entry into
7890 <file>/etc/inetd.conf</file>, the entry must be preceded with
7891 exactly one hash character (<tt>#</tt>). Such lines are
7892 treated as "commented out by user" by the
7893 <prgn>update-inetd</prgn> script and are not changed or
7894 activated during package updates.
7899 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7903 Some programs need to create pseudo-ttys. This should be done
7904 using Unix98 ptys if the C library supports it. The resulting
7905 program must not be installed setuid root, unless that
7906 is required for other functionality.
7910 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7911 <file>/var/log/lastlog</file> must be installed writable by
7912 group <tt>utmp</tt>. Programs which need to modify those
7913 files must be installed setgid <tt>utmp</tt>.
7918 <heading>Editors and pagers</heading>
7921 Some programs have the ability to launch an editor or pager
7922 program to edit or display a text document. Since there are
7923 lots of different editors and pagers available in the Debian
7924 distribution, the system administrator and each user should
7925 have the possibility to choose their preferred editor and
7930 In addition, every program should choose a good default
7931 editor/pager if none is selected by the user or system
7936 Thus, every program that launches an editor or pager must
7937 use the EDITOR or PAGER environment variable to determine
7938 the editor or pager the user wishes to use. If these
7939 variables are not set, the programs <file>/usr/bin/editor</file>
7940 and <file>/usr/bin/pager</file> should be used, respectively.
7944 These two files are managed through the <prgn>dpkg</prgn>
7945 "alternatives" mechanism. Thus every package providing an
7946 editor or pager must call the
7947 <prgn>update-alternatives</prgn> script to register these
7952 If it is very hard to adapt a program to make use of the
7953 EDITOR or PAGER variables, that program may be configured to
7954 use <file>/usr/bin/sensible-editor</file> and
7955 <file>/usr/bin/sensible-pager</file> as the editor or pager
7956 program respectively. These are two scripts provided in the
7957 <package>sensible-utils</package> package that check the EDITOR
7958 and PAGER variables and launch the appropriate program, and fall
7959 back to <file>/usr/bin/editor</file>
7960 and <file>/usr/bin/pager</file> if the variable is not set.
7964 A program may also use the VISUAL environment variable to
7965 determine the user's choice of editor. If it exists, it
7966 should take precedence over EDITOR. This is in fact what
7967 <file>/usr/bin/sensible-editor</file> does.
7971 It is not required for a package to depend on
7972 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7973 package to provide such virtual packages.<footnote>
7974 The Debian base system already provides an editor and a
7980 <sect id="web-appl">
7981 <heading>Web servers and applications</heading>
7984 This section describes the locations and URLs that should
7985 be used by all web servers and web applications in the
7992 Cgi-bin executable files are installed in the
7994 <example compact="compact">
7995 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7997 and should be referred to as
7998 <example compact="compact">
7999 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8005 <p>Access to HTML documents</p>
8008 HTML documents for a package are stored in
8009 <file>/usr/share/doc/<var>package</var></file>
8010 and can be referred to as
8011 <example compact="compact">
8012 http://localhost/doc/<var>package</var>/<var>filename</var>
8017 The web server should restrict access to the document
8018 tree so that only clients on the same host can read
8019 the documents. If the web server does not support such
8020 access controls, then it should not provide access at
8021 all, or ask about providing access during installation.
8026 <p>Access to images</p>
8028 It is recommended that images for a package be stored
8029 in <tt>/usr/share/images/<var>package</var></tt> and
8030 may be referred to through an alias <tt>/images/</tt>
8033 http://localhost/images/<package>/<filename>
8040 <p>Web Document Root</p>
8043 Web Applications should try to avoid storing files in
8044 the Web Document Root. Instead they should use the
8045 /usr/share/doc/<var>package</var> directory for
8046 documents and register the Web Application via the
8047 <package>doc-base</package> package. If access to the
8048 web document root is unavoidable then use
8049 <example compact="compact">
8052 as the Document Root. This might be just a symbolic
8053 link to the location where the system administrator
8054 has put the real document root.
8057 <item><p>Providing httpd and/or httpd-cgi</p>
8059 All web servers should provide the virtual package
8060 <tt>httpd</tt>. If a web server has CGI support it should
8061 provide <tt>httpd-cgi</tt> additionally.
8064 All web applications which do not contain CGI scripts should
8065 depend on <tt>httpd</tt>, all those web applications which
8066 <tt>do</tt> contain CGI scripts, should depend on
8074 <sect id="mail-transport-agents">
8075 <heading>Mail transport, delivery and user agents</heading>
8078 Debian packages which process electronic mail, whether mail
8079 user agents (MUAs) or mail transport agents (MTAs), must
8080 ensure that they are compatible with the configuration
8081 decisions below. Failure to do this may result in lost
8082 mail, broken <tt>From:</tt> lines, and other serious brain
8087 The mail spool is <file>/var/mail</file> and the interface to
8088 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8089 the FHS). On older systems, the mail spool may be
8090 physically located in <file>/var/spool/mail</file>, but all
8091 access to the mail spool should be via the
8092 <file>/var/mail</file> symlink. The mail spool is part of the
8093 base system and not part of the MTA package.
8097 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8098 programs (such as IMAP daemons) must lock the mailbox in an
8099 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8100 be combined with dot locking. To avoid deadlocks, a program
8101 should use <tt>fcntl()</tt> first and dot locking after
8102 this, or alternatively implement the two locking methods in
8103 a non blocking way<footnote>
8104 If it is not possible to establish both locks, the
8105 system shouldn't wait for the second lock to be
8106 established, but remove the first lock, wait a (random)
8107 time, and start over locking again.
8108 </footnote>. Using the functions <tt>maillock</tt> and
8109 <tt>mailunlock</tt> provided by the
8110 <tt>liblockfile*</tt><footnote>
8111 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8112 to use these functions.
8113 </footnote> packages is the recommended way to realize this.
8117 Mailboxes are generally either mode 600 and owned by
8118 <var>user</var> or mode 660 and owned by
8119 <tt><var>user</var>:mail</tt><footnote>
8120 There are two traditional permission schemes for mail spools:
8121 mode 600 with all mail delivery done by processes running as
8122 the destination user, or mode 660 and owned by group mail with
8123 mail delivery done by a process running as a system user in
8124 group mail. Historically, Debian required mode 660 mail
8125 spools to enable the latter model, but that model has become
8126 increasingly uncommon and the principle of least privilege
8127 indicates that mail systems that use the first model should
8128 use permissions of 600. If delivery to programs is permitted,
8129 it's easier to keep the mail system secure if the delivery
8130 agent runs as the destination user. Debian Policy therefore
8131 permits either scheme.
8132 </footnote>. The local system administrator may choose a
8133 different permission scheme; packages should not make
8134 assumptions about the permission and ownership of mailboxes
8135 unless required (such as when creating a new mailbox). A MUA
8136 may remove a mailbox (unless it has nonstandard permissions) in
8137 which case the MTA or another MUA must recreate it if needed.
8141 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8142 be setgid mail to do the locking mentioned above (and
8143 must obviously avoid accessing other users' mailboxes
8144 using this privilege).</p>
8147 <file>/etc/aliases</file> is the source file for the system mail
8148 aliases (e.g., postmaster, usenet, etc.), it is the one
8149 which the sysadmin and <prgn>postinst</prgn> scripts may
8150 edit. After <file>/etc/aliases</file> is edited the program or
8151 human editing it must call <prgn>newaliases</prgn>. All MTA
8152 packages must come with a <prgn>newaliases</prgn> program,
8153 even if it does nothing, but older MTA packages did not do
8154 this so programs should not fail if <prgn>newaliases</prgn>
8155 cannot be found. Note that because of this, all MTA
8156 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8157 <tt>Replaces: mail-transport-agent</tt> control file
8162 The convention of writing <tt>forward to
8163 <var>address</var></tt> in the mailbox itself is not
8164 supported. Use a <tt>.forward</tt> file instead.</p>
8167 The <prgn>rmail</prgn> program used by UUCP
8168 for incoming mail should be <file>/usr/sbin/rmail</file>.
8169 Likewise, <prgn>rsmtp</prgn>, for receiving
8170 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8174 If your package needs to know what hostname to use on (for
8175 example) outgoing news and mail messages which are generated
8176 locally, you should use the file <file>/etc/mailname</file>. It
8177 will contain the portion after the username and <tt>@</tt>
8178 (at) sign for email addresses of users on the machine
8179 (followed by a newline).
8183 Such a package should check for the existence of this file
8184 when it is being configured. If it exists, it should be
8185 used without comment, although an MTA's configuration script
8186 may wish to prompt the user even if it finds that this file
8187 exists. If the file does not exist, the package should
8188 prompt the user for the value (preferably using
8189 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8190 as well as using it in the package's configuration. The
8191 prompt should make it clear that the name will not just be
8192 used by that package. For example, in this situation the
8193 <tt>inn</tt> package could say something like:
8194 <example compact="compact">
8195 Please enter the "mail name" of your system. This is the
8196 hostname portion of the address to be shown on outgoing
8197 news and mail messages. The default is
8198 <var>syshostname</var>, your system's host name. Mail
8199 name ["<var>syshostname</var>"]:
8201 where <var>syshostname</var> is the output of <tt>hostname
8207 <heading>News system configuration</heading>
8210 All the configuration files related to the NNTP (news)
8211 servers and clients should be located under
8212 <file>/etc/news</file>.</p>
8215 There are some configuration issues that apply to a number
8216 of news clients and server packages on the machine. These
8220 <tag><file>/etc/news/organization</file></tag>
8222 A string which should appear as the
8223 organization header for all messages posted
8224 by NNTP clients on the machine
8227 <tag><file>/etc/news/server</file></tag>
8229 Contains the FQDN of the upstream NNTP
8230 server, or localhost if the local machine is
8235 Other global files may be added as required for cross-package news
8242 <heading>Programs for the X Window System</heading>
8245 <heading>Providing X support and package priorities</heading>
8248 Programs that can be configured with support for the X
8249 Window System must be configured to do so and must declare
8250 any package dependencies necessary to satisfy their
8251 runtime requirements when using the X Window System. If
8252 such a package is of higher priority than the X packages
8253 on which it depends, it is required that either the
8254 X-specific components be split into a separate package, or
8255 that an alternative version of the package, which includes
8256 X support, be provided, or that the package's priority be
8262 <heading>Packages providing an X server</heading>
8265 Packages that provide an X server that, directly or
8266 indirectly, communicates with real input and display
8267 hardware should declare in their control data that they
8268 provide the virtual package <tt>xserver</tt>.<footnote>
8269 This implements current practice, and provides an
8270 actual policy for usage of the <tt>xserver</tt>
8271 virtual package which appears in the virtual packages
8272 list. In a nutshell, X servers that interface
8273 directly with the display and input hardware or via
8274 another subsystem (e.g., GGI) should provide
8275 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8276 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8282 <heading>Packages providing a terminal emulator</heading>
8285 Packages that provide a terminal emulator for the X Window
8286 System which meet the criteria listed below should declare
8287 in their control data that they provide the virtual
8288 package <tt>x-terminal-emulator</tt>. They should also
8289 register themselves as an alternative for
8290 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8295 To be an <tt>x-terminal-emulator</tt>, a program must:
8296 <list compact="compact">
8298 Be able to emulate a DEC VT100 terminal, or a
8299 compatible terminal.
8303 Support the command-line option <tt>-e
8304 <var>command</var></tt>, which creates a new
8305 terminal window<footnote>
8306 "New terminal window" does not necessarily mean
8307 a new top-level X window directly parented by
8308 the window manager; it could, if the terminal
8309 emulator application were so coded, be a new
8310 "view" in a multiple-document interface (MDI).
8312 and runs the specified <var>command</var>,
8313 interpreting the entirety of the rest of the command
8314 line as a command to pass straight to exec, in the
8315 manner that <tt>xterm</tt> does.
8319 Support the command-line option <tt>-T
8320 <var>title</var></tt>, which creates a new terminal
8321 window with the window title <var>title</var>.
8328 <heading>Packages providing a window manager</heading>
8331 Packages that provide a window manager should declare in
8332 their control data that they provide the virtual package
8333 <tt>x-window-manager</tt>. They should also register
8334 themselves as an alternative for
8335 <file>/usr/bin/x-window-manager</file>, with a priority
8336 calculated as follows:
8337 <list compact="compact">
8339 Start with a priority of 20.
8343 If the window manager supports the Debian menu
8344 system, add 20 points if this support is available
8345 in the package's default configuration (i.e., no
8346 configuration files belonging to the system or user
8347 have to be edited to activate the feature); if
8348 configuration files must be modified, add only 10
8354 If the window manager complies with <url
8355 id="http://www.freedesktop.org/Standards/wm-spec"
8356 name="The Window Manager Specification Project">,
8357 written by the <url id="http://www.freedesktop.org/"
8358 name="Free Desktop Group">, add 40 points.
8362 If the window manager permits the X session to be
8363 restarted using a <em>different</em> window manager
8364 (without killing the X server) in its default
8365 configuration, add 10 points; otherwise add none.
8372 <heading>Packages providing fonts</heading>
8375 Packages that provide fonts for the X Window
8377 For the purposes of Debian Policy, a "font for the X
8378 Window System" is one which is accessed via X protocol
8379 requests. Fonts for the Linux console, for PostScript
8380 renderer, or any other purpose, do not fit this
8381 definition. Any tool which makes such fonts available
8382 to the X Window System, however, must abide by this
8385 must do a number of things to ensure that they are both
8386 available without modification of the X or font server
8387 configuration, and that they do not corrupt files used by
8388 other font packages to register information about
8392 Fonts of any type supported by the X Window System
8393 must be in a separate binary package from any
8394 executables, libraries, or documentation (except
8395 that specific to the fonts shipped, such as their
8396 license information). If one or more of the fonts
8397 so packaged are necessary for proper operation of
8398 the package with which they are associated the font
8399 package may be Recommended; if the fonts merely
8400 provide an enhancement, a Suggests relationship may
8401 be used. Packages must not Depend on font
8403 This is because the X server may retrieve fonts
8404 from the local file system or over the network
8405 from an X font server; the Debian package system
8406 is empowered to deal only with the local
8412 BDF fonts must be converted to PCF fonts with the
8413 <prgn>bdftopcf</prgn> utility (available in the
8414 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8415 placed in a directory that corresponds to their
8417 <list compact="compact">
8419 100 dpi fonts must be placed in
8420 <file>/usr/share/fonts/X11/100dpi/</file>.
8424 75 dpi fonts must be placed in
8425 <file>/usr/share/fonts/X11/75dpi/</file>.
8429 Character-cell fonts, cursor fonts, and other
8430 low-resolution fonts must be placed in
8431 <file>/usr/share/fonts/X11/misc/</file>.
8437 Type 1 fonts must be placed in
8438 <file>/usr/share/fonts/X11/Type1/</file>. If font
8439 metric files are available, they must be placed here
8444 Subdirectories of <file>/usr/share/fonts/X11/</file>
8445 other than those listed above must be neither
8446 created nor used. (The <file>PEX</file>, <file>CID</file>,
8447 <file>Speedo</file>, and <file>cyrillic</file> directories
8448 are excepted for historical reasons, but installation of
8449 files into these directories remains discouraged.)
8453 Font packages may, instead of placing files directly
8454 in the X font directories listed above, provide
8455 symbolic links in that font directory pointing to
8456 the files' actual location in the filesystem. Such
8457 a location must comply with the FHS.
8461 Font packages should not contain both 75dpi and
8462 100dpi versions of a font. If both are available,
8463 they should be provided in separate binary packages
8464 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8465 the names of the packages containing the
8466 corresponding fonts.
8470 Fonts destined for the <file>misc</file> subdirectory
8471 should not be included in the same package as 75dpi
8472 or 100dpi fonts; instead, they should be provided in
8473 a separate package with <tt>-misc</tt> appended to
8478 Font packages must not provide the files
8479 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8480 <file>fonts.scale</file> in a font directory:
8483 <file>fonts.dir</file> files must not be provided at all.
8487 <file>fonts.alias</file> and <file>fonts.scale</file>
8488 files, if needed, should be provided in the
8490 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8491 where <var>fontdir</var> is the name of the
8493 <file>/usr/share/fonts/X11/</file> where the
8494 package's corresponding fonts are stored
8495 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8496 <var>package</var> is the name of the package
8497 that provides these fonts, and
8498 <var>extension</var> is either <tt>scale</tt>
8499 or <tt>alias</tt>, whichever corresponds to
8506 Font packages must declare a dependency on
8507 <tt>xfonts-utils</tt> in their control
8512 Font packages that provide one or more
8513 <file>fonts.scale</file> files as described above must
8514 invoke <prgn>update-fonts-scale</prgn> on each
8515 directory into which they installed fonts
8516 <em>before</em> invoking
8517 <prgn>update-fonts-dir</prgn> on that directory.
8518 This invocation must occur in both the
8519 <prgn>postinst</prgn> (for all arguments) and
8520 <prgn>postrm</prgn> (for all arguments except
8521 <tt>upgrade</tt>) scripts.
8525 Font packages that provide one or more
8526 <file>fonts.alias</file> files as described above must
8527 invoke <prgn>update-fonts-alias</prgn> on each
8528 directory into which they installed fonts. This
8529 invocation must occur in both the
8530 <prgn>postinst</prgn> (for all arguments) and
8531 <prgn>postrm</prgn> (for all arguments except
8532 <tt>upgrade</tt>) scripts.
8536 Font packages must invoke
8537 <prgn>update-fonts-dir</prgn> on each directory into
8538 which they installed fonts. This invocation must
8539 occur in both the <prgn>postinst</prgn> (for all
8540 arguments) and <prgn>postrm</prgn> (for all
8541 arguments except <tt>upgrade</tt>) scripts.
8545 Font packages must not provide alias names for the
8546 fonts they include which collide with alias names
8547 already in use by fonts already packaged.
8551 Font packages must not provide fonts with the same
8552 XLFD registry name as another font already packaged.
8558 <sect1 id="appdefaults">
8559 <heading>Application defaults files</heading>
8562 Application defaults files must be installed in the
8563 directory <file>/etc/X11/app-defaults/</file> (use of a
8564 localized subdirectory of <file>/etc/X11/</file> as described
8565 in the <em>X Toolkit Intrinsics - C Language
8566 Interface</em> manual is also permitted). They must be
8567 registered as <tt>conffile</tt>s or handled as
8568 configuration files.
8572 Customization of programs' X resources may also be
8573 supported with the provision of a file with the same name
8574 as that of the package placed in the
8575 <file>/etc/X11/Xresources/</file> directory, which must
8576 registered as a <tt>conffile</tt> or handled as a
8577 configuration file.<footnote>
8578 Note that this mechanism is not the same as using
8579 app-defaults; app-defaults are tied to the client
8580 binary on the local file system, whereas X resources
8581 are stored in the X server and affect all connecting
8588 <heading>Installation directory issues</heading>
8591 Historically, packages using the X Window System used a
8592 separate set of installation directories from other packages.
8593 This practice has been discontinued and packages using the X
8594 Window System should now generally be installed in the same
8595 directories as any other package. Specifically, packages must
8596 not install files under the <file>/usr/X11R6/</file> directory
8597 and the <file>/usr/X11R6/</file> directory hierarchy should be
8598 regarded as obsolete.
8602 Include files previously installed under
8603 <file>/usr/X11R6/include/X11/</file> should be installed into
8604 <file>/usr/include/X11/</file>. For files previously
8605 installed into subdirectories of
8606 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8607 determine if subdirectories of <file>/usr/lib/</file> and
8608 <file>/usr/share/</file> can be used. If not, a subdirectory
8609 of <file>/usr/lib/X11/</file> should be used.
8613 Configuration files for window, display, or session managers
8614 or other applications that are tightly integrated with the X
8615 Window System may be placed in a subdirectory
8616 of <file>/etc/X11/</file> corresponding to the package name.
8617 Other X Window System applications should use
8618 the <file>/etc/</file> directory unless otherwise mandated by
8619 policy (such as for <ref id="appdefaults">).
8624 <heading>The OSF/Motif and OpenMotif libraries</heading>
8627 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8628 OpenMotif libraries</em><footnote>
8629 OSF/Motif and OpenMotif are collectively referred to as
8630 "Motif" in this policy document.
8632 should be compiled against and tested with LessTif (a free
8633 re-implementation of Motif) instead. If the maintainer
8634 judges that the program or programs do not work
8635 sufficiently well with LessTif to be distributed and
8636 supported, but do so when compiled against Motif, then two
8637 versions of the package should be created; one linked
8638 statically against Motif and with <tt>-smotif</tt>
8639 appended to the package name, and one linked dynamically
8640 against Motif and with <tt>-dmotif</tt> appended to the
8645 Both Motif-linked versions are dependent
8646 upon non-DFSG-compliant software and thus cannot be
8647 uploaded to the <em>main</em> distribution; if the
8648 software is itself DFSG-compliant it may be uploaded to
8649 the <em>contrib</em> distribution. While known existing
8650 versions of Motif permit unlimited redistribution of
8651 binaries linked against the library (whether statically or
8652 dynamically), it is the package maintainer's
8653 responsibility to determine whether this is permitted by
8654 the license of the copy of Motif in their possession.
8660 <heading>Perl programs and modules</heading>
8663 Perl programs and modules should follow the current Perl policy.
8667 The Perl policy can be found in the <tt>perl-policy</tt>
8668 files in the <tt>debian-policy</tt> package.
8669 It is also available from the Debian web mirrors at
8670 <tt><url name="/doc/packaging-manuals/perl-policy/"
8671 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8676 <heading>Emacs lisp programs</heading>
8679 Please refer to the "Debian Emacs Policy" for details of how to
8680 package emacs lisp programs.
8684 The Emacs policy is available in
8685 <file>debian-emacs-policy.gz</file> of the
8686 <package>emacsen-common</package> package.
8687 It is also available from the Debian web mirrors at
8688 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8689 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8694 <heading>Games</heading>
8697 The permissions on <file>/var/games</file> are mode 755, owner
8698 <tt>root</tt> and group <tt>root</tt>.
8702 Each game decides on its own security policy.</p>
8705 Games which require protected, privileged access to
8706 high-score files, saved games, etc., may be made
8707 set-<em>group</em>-id (mode 2755) and owned by
8708 <tt>root:games</tt>, and use files and directories with
8709 appropriate permissions (770 <tt>root:games</tt>, for
8710 example). They must not be made
8711 set-<em>user</em>-id, as this causes security problems. (If
8712 an attacker can subvert any set-user-id game they can
8713 overwrite the executable of any other, causing other players
8714 of these games to run a Trojan horse program. With a
8715 set-group-id game the attacker only gets access to less
8716 important game data, and if they can get at the other
8717 players' accounts at all it will take considerably more
8721 Some packages, for example some fortune cookie programs, are
8722 configured by the upstream authors to install with their
8723 data files or other static information made unreadable so
8724 that they can only be accessed through set-id programs
8725 provided. You should not do this in a Debian package: anyone can
8726 download the <file>.deb</file> file and read the data from it,
8727 so there is no point making the files unreadable. Not
8728 making the files unreadable also means that you don't have
8729 to make so many programs set-id, which reduces the risk of a
8733 As described in the FHS, binaries of games should be
8734 installed in the directory <file>/usr/games</file>. This also
8735 applies to games that use the X Window System. Manual pages
8736 for games (X and non-X games) should be installed in
8737 <file>/usr/share/man/man6</file>.</p>
8743 <heading>Documentation</heading>
8746 <heading>Manual pages</heading>
8749 You should install manual pages in <prgn>nroff</prgn> source
8750 form, in appropriate places under <file>/usr/share/man</file>.
8751 You should only use sections 1 to 9 (see the FHS for more
8752 details). You must not install a pre-formatted "cat page".
8756 Each program, utility, and function should have an
8757 associated manual page included in the same package. It is
8758 suggested that all configuration files also have a manual
8759 page included as well. Manual pages for protocols and other
8760 auxiliary things are optional.
8764 If no manual page is available, this is considered as a bug
8765 and should be reported to the Debian Bug Tracking System (the
8766 maintainer of the package is allowed to write this bug report
8767 themselves, if they so desire). Do not close the bug report
8768 until a proper man page is available.<footnote>
8769 It is not very hard to write a man page. See the
8770 <url id="http://www.schweikhardt.net/man_page_howto.html"
8771 name="Man-Page-HOWTO">,
8772 <manref name="man" section="7">, the examples
8773 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8774 the helper programs <prgn>help2man</prgn>, or the
8775 directory <file>/usr/share/doc/man-db/examples</file>.
8780 You may forward a complaint about a missing man page to the
8781 upstream authors, and mark the bug as forwarded in the
8782 Debian bug tracking system. Even though the GNU Project do
8783 not in general consider the lack of a man page to be a bug,
8784 we do; if they tell you that they don't consider it a bug
8785 you should leave the bug in our bug tracking system open
8790 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8794 If one man page needs to be accessible via several names it
8795 is better to use a symbolic link than the <file>.so</file>
8796 feature, but there is no need to fiddle with the relevant
8797 parts of the upstream source to change from <file>.so</file> to
8798 symlinks: don't do it unless it's easy. You should not
8799 create hard links in the manual page directories, nor put
8800 absolute filenames in <file>.so</file> directives. The filename
8801 in a <file>.so</file> in a man page should be relative to the
8802 base of the man page tree (usually
8803 <file>/usr/share/man</file>). If you do not create any links
8804 (whether symlinks, hard links, or <tt>.so</tt> directives)
8805 in the file system to the alternate names of the man page,
8806 then you should not rely on <prgn>man</prgn> finding your
8807 man page under those names based solely on the information in
8808 the man page's header.<footnote>
8809 Supporting this in <prgn>man</prgn> often requires
8810 unreasonable processing time to find a manual page or to
8811 report that none exists, and moves knowledge into man's
8812 database that would be better left in the file system.
8813 This support is therefore deprecated and will cease to
8814 be present in the future.
8819 Manual pages in locale-specific subdirectories of
8820 <file>/usr/share/man</file> should use either UTF-8 or the usual
8821 legacy encoding for that language (normally the one corresponding
8822 to the shortest relevant locale name in
8823 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8824 <file>/usr/share/man/fr</file> should use either UTF-8 or
8825 ISO-8859-1.<footnote>
8826 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8827 use. In future, all manual pages will be required to use
8833 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8834 included in the subdirectory name unless it indicates a
8835 significant difference in the language, as this excludes
8836 speakers of the language in other countries.<footnote>
8837 At the time of writing, Chinese and Portuguese are the main
8838 languages with such differences, so <file>pt_BR</file>,
8839 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8844 If a localized version of a manual page is provided, it should
8845 either be up-to-date or it should be obvious to the reader that
8846 it is outdated and the original manual page should be used
8847 instead. This can be done either by a note at the beginning of
8848 the manual page or by showing the missing or changed portions in
8849 the original language instead of the target language.
8854 <heading>Info documents</heading>
8857 Info documents should be installed in <file>/usr/share/info</file>.
8858 They should be compressed with <tt>gzip -9</tt>.
8862 The <prgn>install-info</prgn> program maintains a directory of
8863 installed info documents in <file>/usr/share/info/dir</file> for
8864 the use of info readers.<footnote>
8865 It was previously necessary for packages installing info
8866 documents to run <prgn>install-info</prgn> from maintainer
8867 scripts. This is no longer necessary. The installation
8868 system now uses dpkg triggers.
8870 This file must not be included in packages. Packages containing
8871 info documents should depend on <tt>dpkg (>= 1.15.4) |
8872 install-info</tt> to ensure that the directory file is properly
8873 rebuilt during partial upgrades from Debian 5.0 (lenny) and
8878 Info documents should contain section and directory entry
8879 information in the document for the use
8880 of <prgn>install-info</prgn>. The section should be specified
8881 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8882 space and the section of this info page. The directory entry or
8883 entries should be included between
8884 a <tt>START-INFO-DIR-ENTRY</tt> line and
8885 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8887 INFO-DIR-SECTION Individual utilities
8888 START-INFO-DIR-ENTRY
8889 * example: (example). An example info directory entry.
8892 To determine which section to use, you should look
8893 at <file>/usr/share/info/dir</file> on your system and choose
8894 the most relevant (or create a new section if none of the
8895 current sections are relevant).<footnote>
8896 Normally, info documents are generated from Texinfo source.
8897 To include this information in the generated info document, if
8898 it is absent, add commands like:
8900 @dircategory Individual utilities
8902 * example: (example). An example info directory entry.
8905 to the Texinfo source of the document and ensure that the info
8906 documents are rebuilt from source during the package build.
8912 <heading>Additional documentation</heading>
8915 Any additional documentation that comes with the package may
8916 be installed at the discretion of the package maintainer.
8917 Plain text documentation should be installed in the directory
8918 <file>/usr/share/doc/<var>package</var></file>, where
8919 <var>package</var> is the name of the package, and
8920 compressed with <tt>gzip -9</tt> unless it is small.
8924 If a package comes with large amounts of documentation which
8925 many users of the package will not require you should create
8926 a separate binary package to contain it, so that it does not
8927 take up disk space on the machines of users who do not need
8928 or want it installed.</p>
8931 It is often a good idea to put text information files
8932 (<file>README</file>s, changelogs, and so forth) that come with
8933 the source package in <file>/usr/share/doc/<var>package</var></file>
8934 in the binary package. However, you don't need to install
8935 the instructions for building and installing the package, of
8939 Packages must not require the existence of any files in
8940 <file>/usr/share/doc/</file> in order to function
8942 The system administrator should be able to
8943 delete files in <file>/usr/share/doc/</file> without causing
8944 any programs to break.
8946 Any files that are referenced by programs but are also
8947 useful as stand alone documentation should be installed under
8948 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8949 <file>/usr/share/doc/<var>package</var></file>.
8953 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8954 link to another directory in <file>/usr/share/doc</file> only if
8955 the two packages both come from the same source and the
8956 first package Depends on the second.<footnote>
8958 Please note that this does not override the section on
8959 changelog files below, so the file
8960 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8961 must refer to the changelog for the current version of
8962 <var>package</var> in question. In practice, this means
8963 that the sources of the target and the destination of the
8964 symlink must be the same (same source package and
8971 Former Debian releases placed all additional documentation
8972 in <file>/usr/doc/<var>package</var></file>. This has been
8973 changed to <file>/usr/share/doc/<var>package</var></file>,
8974 and packages must not put documentation in the directory
8975 <file>/usr/doc/<var>package</var></file>. <footnote>
8976 At this phase of the transition, we no longer require a
8977 symbolic link in <file>/usr/doc/</file>. At a later point,
8978 policy shall change to make the symbolic links a bug.
8984 <heading>Preferred documentation formats</heading>
8987 The unification of Debian documentation is being carried out
8991 If your package comes with extensive documentation in a
8992 markup format that can be converted to various other formats
8993 you should if possible ship HTML versions in a binary
8994 package, in the directory
8995 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8996 its subdirectories.<footnote>
8997 The rationale: The important thing here is that HTML
8998 docs should be available in <em>some</em> package, not
8999 necessarily in the main binary package.
9004 Other formats such as PostScript may be provided at the
9005 package maintainer's discretion.
9009 <sect id="copyrightfile">
9010 <heading>Copyright information</heading>
9013 Every package must be accompanied by a verbatim copy of its
9014 copyright and distribution license in the file
9015 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9016 file must neither be compressed nor be a symbolic link.
9020 In addition, the copyright file must say where the upstream
9021 sources (if any) were obtained. It should name the original
9022 authors of the package and the Debian maintainer(s) who were
9023 involved with its creation.
9027 Packages in the <em>contrib</em> or <em>non-free</em> archive
9028 areas should state in the copyright file that the package is not
9029 part of the Debian GNU/Linux distribution and briefly explain
9034 A copy of the file which will be installed in
9035 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9036 be in <file>debian/copyright</file> in the source package.
9040 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9041 link to another directory in <file>/usr/share/doc</file> only if
9042 the two packages both come from the same source and the
9043 first package Depends on the second. These rules are
9044 important because copyrights must be extractable by
9049 Packages distributed under the UCB BSD license, the Apache
9050 license (version 2.0), the Artistic license, the GNU GPL
9051 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9052 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9053 files under <file>/usr/share/common-licenses</file>,<footnote>
9056 <file>/usr/share/common-licenses/BSD</file>,
9057 <file>/usr/share/common-licenses/Apache-2.0</file>,
9058 <file>/usr/share/common-licenses/Artistic</file>,
9059 <file>/usr/share/common-licenses/GPL-2</file>,
9060 <file>/usr/share/common-licenses/GPL-3</file>,
9061 <file>/usr/share/common-licenses/LGPL-2</file>,
9062 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9063 <file>/usr/share/common-licenses/LGPL-3</file>,
9064 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9065 <file>/usr/share/common-licenses/GFDL-1.3</file>
9068 </footnote> rather than quoting them in the copyright
9073 You should not use the copyright file as a general <file>README</file>
9074 file. If your package has such a file it should be
9075 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9076 <file>README.Debian</file> or some other appropriate place.</p>
9080 <heading>Examples</heading>
9083 Any examples (configurations, source files, whatever),
9084 should be installed in a directory
9085 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9086 files should not be referenced by any program: they're there
9087 for the benefit of the system administrator and users as
9088 documentation only. Architecture-specific example files
9089 should be installed in a directory
9090 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9092 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9093 latter directory itself may be a symbolic link to the
9098 If the purpose of a package is to provide examples, then the
9099 example files may be installed into
9100 <file>/usr/share/doc/<var>package</var></file>.
9104 <sect id="changelogs">
9105 <heading>Changelog files</heading>
9108 Packages that are not Debian-native must contain a
9109 compressed copy of the <file>debian/changelog</file> file from
9110 the Debian source tree in
9111 <file>/usr/share/doc/<var>package</var></file> with the name
9112 <file>changelog.Debian.gz</file>.
9116 If an upstream changelog is available, it should be accessible as
9117 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9118 plain text. If the upstream changelog is distributed in
9119 HTML, it should be made available in that form as
9120 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9121 and a plain text <file>changelog.gz</file> should be generated
9122 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9123 the upstream changelog files do not already conform to this
9124 naming convention, then this may be achieved either by
9125 renaming the files, or by adding a symbolic link, at the
9126 maintainer's discretion.<footnote>
9127 Rationale: People should not have to look in places for
9128 upstream changelogs merely because they are given
9129 different names or are distributed in HTML format.
9134 All of these files should be installed compressed using
9135 <tt>gzip -9</tt>, as they will become large with time even
9136 if they start out small.
9140 If the package has only one changelog which is used both as
9141 the Debian changelog and the upstream one because there is
9142 no separate upstream maintainer then that changelog should
9143 usually be installed as
9144 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9145 there is a separate upstream maintainer, but no upstream
9146 changelog, then the Debian changelog should still be called
9147 <file>changelog.Debian.gz</file>.
9151 For details about the format and contents of the Debian
9152 changelog file, please see <ref id="dpkgchangelog">.
9157 <appendix id="pkg-scope">
9158 <heading>Introduction and scope of these appendices</heading>
9161 These appendices are taken essentially verbatim from the
9162 now-deprecated Packaging Manual, version 3.2.1.0. They are
9163 the chapters which are likely to be of use to package
9164 maintainers and which have not already been included in the
9165 policy document itself. Most of these sections are very likely
9166 not relevant to policy; they should be treated as
9167 documentation for the packaging system. Please note that these
9168 appendices are included for convenience, and for historical
9169 reasons: they used to be part of policy package, and they have
9170 not yet been incorporated into dpkg documentation. However,
9171 they still have value, and hence they are presented here.
9175 They have not yet been checked to ensure that they are
9176 compatible with the contents of policy, and if there are any
9177 contradictions, the version in the main policy document takes
9178 precedence. The remaining chapters of the old Packaging
9179 Manual have also not been read in detail to ensure that there
9180 are not parts which have been left out. Both of these will be
9185 Certain parts of the Packaging manual were integrated into the
9186 Policy Manual proper, and removed from the appendices. Links
9187 have been placed from the old locations to the new ones.
9191 <prgn>dpkg</prgn> is a suite of programs for creating binary
9192 package files and installing and removing them on Unix
9194 <prgn>dpkg</prgn> is targeted primarily at Debian
9195 GNU/Linux, but may work on or be ported to other
9201 The binary packages are designed for the management of
9202 installed executable programs (usually compiled binaries) and
9203 their associated data, though source code examples and
9204 documentation are provided as part of some packages.</p>
9207 This manual describes the technical aspects of creating Debian
9208 binary packages (<file>.deb</file> files). It documents the
9209 behavior of the package management programs
9210 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9211 they interact with packages.</p>
9214 It also documents the interaction between
9215 <prgn>dselect</prgn>'s core and the access method scripts it
9216 uses to actually install the selected packages, and describes
9217 how to create a new access method.</p>
9220 This manual does not go into detail about the options and
9221 usage of the package building and installation tools. It
9222 should therefore be read in conjunction with those programs'
9227 The utility programs which are provided with <prgn>dpkg</prgn>
9228 for managing various system configuration and similar issues,
9229 such as <prgn>update-rc.d</prgn> and
9230 <prgn>install-info</prgn>, are not described in detail here -
9231 please see their man pages.
9235 It is assumed that the reader is reasonably familiar with the
9236 <prgn>dpkg</prgn> System Administrators' manual.
9237 Unfortunately this manual does not yet exist.
9241 The Debian version of the FSF's GNU hello program is provided
9242 as an example for people wishing to create Debian
9243 packages. The Debian <prgn>debmake</prgn> package is
9244 recommended as a very helpful tool in creating and maintaining
9245 Debian packages. However, while the tools and examples are
9246 helpful, they do not replace the need to read and follow the
9247 Policy and Programmer's Manual.</p>
9250 <appendix id="pkg-binarypkg">
9251 <heading>Binary packages (from old Packaging Manual)</heading>
9254 The binary package has two main sections. The first part
9255 consists of various control information files and scripts used
9256 by <prgn>dpkg</prgn> when installing and removing. See <ref
9257 id="pkg-controlarea">.
9261 The second part is an archive containing the files and
9262 directories to be installed.
9266 In the future binary packages may also contain other
9267 components, such as checksums and digital signatures. The
9268 format for the archive is described in full in the
9269 <file>deb(5)</file> man page.
9273 <sect id="pkg-bincreating"><heading>Creating package files -
9274 <prgn>dpkg-deb</prgn>
9278 All manipulation of binary package files is done by
9279 <prgn>dpkg-deb</prgn>; it's the only program that has
9280 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9281 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9282 will spot that the options requested are appropriate to
9283 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9288 In order to create a binary package you must make a
9289 directory tree which contains all the files and directories
9290 you want to have in the file system data part of the package.
9291 In Debian-format source packages this directory is usually
9292 <file>debian/tmp</file>, relative to the top of the package's
9297 They should have the locations (relative to the root of the
9298 directory tree you're constructing) ownerships and
9299 permissions which you want them to have on the system when
9304 With current versions of <prgn>dpkg</prgn> the uid/username
9305 and gid/groupname mappings for the users and groups being
9306 used should be the same on the system where the package is
9307 built and the one where it is installed.
9311 You need to add one special directory to the root of the
9312 miniature file system tree you're creating:
9313 <prgn>DEBIAN</prgn>. It should contain the control
9314 information files, notably the binary package control file
9315 (see <ref id="pkg-controlfile">).
9319 The <prgn>DEBIAN</prgn> directory will not appear in the
9320 file system archive of the package, and so won't be installed
9321 by <prgn>dpkg</prgn> when the package is installed.
9325 When you've prepared the package, you should invoke:
9327 dpkg --build <var>directory</var>
9332 This will build the package in
9333 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9334 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9335 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9340 See the man page <manref name="dpkg-deb" section="8"> for details of how
9341 to examine the contents of this newly-created file. You may find the
9342 output of following commands enlightening:
9344 dpkg-deb --info <var>filename</var>.deb
9345 dpkg-deb --contents <var>filename</var>.deb
9346 dpkg --contents <var>filename</var>.deb
9348 To view the copyright file for a package you could use this command:
9350 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9355 <sect id="pkg-controlarea">
9356 <heading>Package control information files</heading>
9359 The control information portion of a binary package is a
9360 collection of files with names known to <prgn>dpkg</prgn>.
9361 It will treat the contents of these files specially - some
9362 of them contain information used by <prgn>dpkg</prgn> when
9363 installing or removing the package; others are scripts which
9364 the package maintainer wants <prgn>dpkg</prgn> to run.
9368 It is possible to put other files in the package control
9369 area, but this is not generally a good idea (though they
9370 will largely be ignored).
9374 Here is a brief list of the control info files supported by
9375 <prgn>dpkg</prgn> and a summary of what they're used for.
9380 <tag><tt>control</tt>
9383 This is the key description file used by
9384 <prgn>dpkg</prgn>. It specifies the package's name
9385 and version, gives its description for the user,
9386 states its relationships with other packages, and so
9387 forth. See <ref id="sourcecontrolfiles"> and
9388 <ref id="binarycontrolfiles">.
9392 It is usually generated automatically from information
9393 in the source package by the
9394 <prgn>dpkg-gencontrol</prgn> program, and with
9395 assistance from <prgn>dpkg-shlibdeps</prgn>.
9396 See <ref id="pkg-sourcetools">.
9400 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9405 These are executable files (usually scripts) which
9406 <prgn>dpkg</prgn> runs during installation, upgrade
9407 and removal of packages. They allow the package to
9408 deal with matters which are particular to that package
9409 or require more complicated processing than that
9410 provided by <prgn>dpkg</prgn>. Details of when and
9411 how they are called are in <ref id="maintainerscripts">.
9415 It is very important to make these scripts idempotent.
9416 See <ref id="idempotency">.
9420 The maintainer scripts are guaranteed to run with a
9421 controlling terminal and can interact with the user.
9422 See <ref id="controllingterminal">.
9426 <tag><tt>conffiles</tt>
9429 This file contains a list of configuration files which
9430 are to be handled automatically by <prgn>dpkg</prgn>
9431 (see <ref id="pkg-conffiles">). Note that not necessarily
9432 every configuration file should be listed here.
9435 <tag><tt>shlibs</tt>
9438 This file contains a list of the shared libraries
9439 supplied by the package, with dependency details for
9440 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9441 when it determines what dependencies are required in a
9442 package control file. The <tt>shlibs</tt> file format
9443 is described on <ref id="shlibs">.
9448 <sect id="pkg-controlfile">
9449 <heading>The main control information file: <tt>control</tt></heading>
9452 The most important control information file used by
9453 <prgn>dpkg</prgn> when it installs a package is
9454 <tt>control</tt>. It contains all the package's "vital
9459 The binary package control files of packages built from
9460 Debian sources are made by a special tool,
9461 <prgn>dpkg-gencontrol</prgn>, which reads
9462 <file>debian/control</file> and <file>debian/changelog</file> to
9463 find the information it needs. See <ref id="pkg-sourcepkg"> for
9468 The fields in binary package control files are listed in
9469 <ref id="binarycontrolfiles">.
9473 A description of the syntax of control files and the purpose
9474 of the fields is available in <ref id="controlfields">.
9479 <heading>Time Stamps</heading>
9482 See <ref id="timestamps">.
9487 <appendix id="pkg-sourcepkg">
9488 <heading>Source packages (from old Packaging Manual) </heading>
9491 The Debian binary packages in the distribution are generated
9492 from Debian sources, which are in a special format to assist
9493 the easy and automatic building of binaries.
9496 <sect id="pkg-sourcetools">
9497 <heading>Tools for processing source packages</heading>
9500 Various tools are provided for manipulating source packages;
9501 they pack and unpack sources and help build of binary
9502 packages and help manage the distribution of new versions.
9506 They are introduced and typical uses described here; see
9507 <manref name="dpkg-source" section="1"> for full
9508 documentation about their arguments and operation.
9512 For examples of how to construct a Debian source package,
9513 and how to use those utilities that are used by Debian
9514 source packages, please see the <prgn>hello</prgn> example
9518 <sect1 id="pkg-dpkg-source">
9520 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9525 This program is frequently used by hand, and is also
9526 called from package-independent automated building scripts
9527 such as <prgn>dpkg-buildpackage</prgn>.
9531 To unpack a package it is typically invoked with
9533 dpkg-source -x <var>.../path/to/filename</var>.dsc
9538 with the <file><var>filename</var>.tar.gz</file> and
9539 <file><var>filename</var>.diff.gz</file> (if applicable) in
9540 the same directory. It unpacks into
9541 <file><var>package</var>-<var>version</var></file>, and if
9543 <file><var>package</var>-<var>version</var>.orig</file>, in
9544 the current directory.
9548 To create a packed source archive it is typically invoked:
9550 dpkg-source -b <var>package</var>-<var>version</var>
9555 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9556 <file>.diff.gz</file> (if appropriate) in the current
9557 directory. <prgn>dpkg-source</prgn> does not clean the
9558 source tree first - this must be done separately if it is
9563 See also <ref id="pkg-sourcearchives">.</p>
9567 <sect1 id="pkg-dpkg-buildpackage">
9569 <prgn>dpkg-buildpackage</prgn> - overall package-building
9574 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9575 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9576 targets <tt>clean</tt>, <tt>build</tt> and
9577 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9578 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9579 source and binary package upload.
9583 It is usually invoked by hand from the top level of the
9584 built or unbuilt source directory. It may be invoked with
9585 no arguments; useful arguments include:
9586 <taglist compact="compact">
9587 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9590 Do not sign the <tt>.changes</tt> file or the
9591 source package <tt>.dsc</tt> file, respectively.</p>
9593 <tag><tt>-p<var>sign-command</var></tt></tag>
9596 Invoke <var>sign-command</var> instead of finding
9597 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9598 <var>sign-command</var> must behave just like
9599 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9601 <tag><tt>-r<var>root-command</var></tt></tag>
9604 When root privilege is required, invoke the command
9605 <var>root-command</var>. <var>root-command</var>
9606 should invoke its first argument as a command, from
9607 the <prgn>PATH</prgn> if necessary, and pass its
9608 second and subsequent arguments to the command it
9609 calls. If no <var>root-command</var> is supplied
9610 then <var>dpkg-buildpackage</var> will take no
9611 special action to gain root privilege, so that for
9612 most packages it will have to be invoked as root to
9615 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9618 Two types of binary-only build and upload - see
9619 <manref name="dpkg-source" section="1">.
9626 <sect1 id="pkg-dpkg-gencontrol">
9628 <prgn>dpkg-gencontrol</prgn> - generates binary package
9633 This program is usually called from <file>debian/rules</file>
9634 (see <ref id="pkg-sourcetree">) in the top level of the source
9639 This is usually done just before the files and directories in the
9640 temporary directory tree where the package is being built have their
9641 permissions and ownerships set and the package is constructed using
9642 <prgn>dpkg-deb/</prgn>
9644 This is so that the control file which is produced has
9645 the right permissions
9650 <prgn>dpkg-gencontrol</prgn> must be called after all the
9651 files which are to go into the package have been placed in
9652 the temporary build directory, so that its calculation of
9653 the installed size of a package is correct.
9657 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9658 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9659 variable substitutions created by
9660 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9665 For a package which generates only one binary package, and
9666 which builds it in <file>debian/tmp</file> relative to the top
9667 of the source package, it is usually sufficient to call
9668 <prgn>dpkg-gencontrol</prgn>.
9672 Sources which build several binaries will typically need
9675 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9676 </example> The <tt>-P</tt> tells
9677 <prgn>dpkg-gencontrol</prgn> that the package is being
9678 built in a non-default directory, and the <tt>-p</tt>
9679 tells it which package's control file should be generated.
9683 <prgn>dpkg-gencontrol</prgn> also adds information to the
9684 list of files in <file>debian/files</file>, for the benefit of
9685 (for example) a future invocation of
9686 <prgn>dpkg-genchanges</prgn>.</p>
9689 <sect1 id="pkg-dpkg-shlibdeps">
9691 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9696 This program is usually called from <file>debian/rules</file>
9697 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9698 id="pkg-sourcetree">), in the top level of the source tree.
9702 Its arguments are executables and shared libraries
9705 They may be specified either in the locations in the
9706 source tree where they are created or in the locations
9707 in the temporary build tree where they are installed
9708 prior to binary package creation.
9710 </footnote> for which shared library dependencies should
9711 be included in the binary package's control file.
9715 If some of the found shared libraries should only
9716 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9717 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9718 by using the <tt>-d<var>dependency-field</var></tt> option
9719 before those executable(s). (Each <tt>-d</tt> option
9720 takes effect until the next <tt>-d</tt>.)
9724 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9725 output control file to be modified. Instead by default it
9726 adds to the <file>debian/substvars</file> file variable
9727 settings like <tt>shlibs:Depends</tt>. These variable
9728 settings must be referenced in dependency fields in the
9729 appropriate per-binary-package sections of the source
9734 For example, a package that generates an essential part
9735 which requires dependencies, and optional parts that
9736 which only require a recommendation, would separate those
9737 two sets of dependencies into two different fields.<footnote>
9738 At the time of writing, an example for this was the
9739 <package/xmms/ package, with Depends used for the xmms
9740 executable, Recommends for the plug-ins and Suggests for
9741 even more optional features provided by unzip.
9743 It can say in its <file>debian/rules</file>:
9745 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9746 -dRecommends <var>optionalpart anotheroptionalpart</var>
9748 and then in its main control file <file>debian/control</file>:
9751 Depends: ${shlibs:Depends}
9752 Recommends: ${shlibs:Recommends}
9758 Sources which produce several binary packages with
9759 different shared library dependency requirements can use
9760 the <tt>-p<var>varnameprefix</var></tt> option to override
9761 the default <tt>shlibs:</tt> prefix (one invocation of
9762 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9763 They can thus produce several sets of dependency
9764 variables, each of the form
9765 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9766 which can be referred to in the appropriate parts of the
9767 binary package control files.
9772 <sect1 id="pkg-dpkg-distaddfile">
9774 <prgn>dpkg-distaddfile</prgn> - adds a file to
9775 <file>debian/files</file>
9779 Some packages' uploads need to include files other than
9780 the source and binary package files.
9784 <prgn>dpkg-distaddfile</prgn> adds a file to the
9785 <file>debian/files</file> file so that it will be included in
9786 the <file>.changes</file> file when
9787 <prgn>dpkg-genchanges</prgn> is run.
9791 It is usually invoked from the <tt>binary</tt> target of
9792 <file>debian/rules</file>:
9794 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9796 The <var>filename</var> is relative to the directory where
9797 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9798 is usually the directory above the top level of the source
9799 tree. The <file>debian/rules</file> target should put the
9800 file there just before or just after calling
9801 <prgn>dpkg-distaddfile</prgn>.
9805 The <var>section</var> and <var>priority</var> are passed
9806 unchanged into the resulting <file>.changes</file> file.
9811 <sect1 id="pkg-dpkg-genchanges">
9813 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9818 This program is usually called by package-independent
9819 automatic building scripts such as
9820 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9825 It is usually called in the top level of a built source
9826 tree, and when invoked with no arguments will print out a
9827 straightforward <file>.changes</file> file based on the
9828 information in the source package's changelog and control
9829 file and the binary and source packages which should have
9835 <sect1 id="pkg-dpkg-parsechangelog">
9837 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9838 representation of a changelog
9842 This program is used internally by
9843 <prgn>dpkg-source</prgn> et al. It may also occasionally
9844 be useful in <file>debian/rules</file> and elsewhere. It
9845 parses a changelog, <file>debian/changelog</file> by default,
9846 and prints a control-file format representation of the
9847 information in it to standard output.
9851 <sect1 id="pkg-dpkg-architecture">
9853 <prgn>dpkg-architecture</prgn> - information about the build and
9858 This program can be used manually, but is also invoked by
9859 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9860 environment or make variables which specify the build and host
9861 architecture for the package building process.
9866 <sect id="pkg-sourcetree">
9867 <heading>The Debianised source tree</heading>
9870 The source archive scheme described later is intended to
9871 allow a Debianised source tree with some associated control
9872 information to be reproduced and transported easily. The
9873 Debianised source tree is a version of the original program
9874 with certain files added for the benefit of the
9875 Debianisation process, and with any other changes required
9876 made to the rest of the source code and installation
9881 The extra files created for Debian are in the subdirectory
9882 <file>debian</file> of the top level of the Debianised source
9883 tree. They are described below.
9886 <sect1 id="pkg-debianrules">
9887 <heading><file>debian/rules</file> - the main building script</heading>
9890 See <ref id="debianrules">.
9895 <sect1 id="pkg-dpkgchangelog">
9896 <heading><file>debian/changelog</file></heading>
9899 See <ref id="dpkgchangelog">.
9902 <sect2><heading>Defining alternative changelog formats
9906 It is possible to use a different format to the standard
9907 one, by providing a parser for the format you wish to
9912 In order to have <tt>dpkg-parsechangelog</tt> run your
9913 parser, you must include a line within the last 40 lines
9914 of your file matching the Perl regular expression:
9915 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9916 parentheses should be the name of the format. For
9917 example, you might say:
9919 @@@ changelog-format: joebloggs @@@
9921 Changelog format names are non-empty strings of alphanumerics.
9925 If such a line exists then <tt>dpkg-parsechangelog</tt>
9926 will look for the parser as
9927 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9929 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9930 it is an error for it not to find it, or for it not to
9931 be an executable program. The default changelog format
9932 is <tt>dpkg</tt>, and a parser for it is provided with
9933 the <tt>dpkg</tt> package.
9937 The parser will be invoked with the changelog open on
9938 standard input at the start of the file. It should read
9939 the file (it may seek if it wishes) to determine the
9940 information required and return the parsed information
9941 to standard output in the form of a series of control
9942 fields in the standard format. By default it should
9943 return information about only the most recent version in
9944 the changelog; it should accept a
9945 <tt>-v<var>version</var></tt> option to return changes
9946 information from all versions present <em>strictly
9947 after</em> <var>version</var>, and it should then be an
9948 error for <var>version</var> not to be present in the
9954 <list compact="compact">
9955 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9956 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9957 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9958 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9959 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9960 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9961 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9966 If several versions are being returned (due to the use
9967 of <tt>-v</tt>), the urgency value should be of the
9968 highest urgency code listed at the start of any of the
9969 versions requested followed by the concatenated
9970 (space-separated) comments from all the versions
9971 requested; the maintainer, version, distribution and
9972 date should always be from the most recent version.
9976 For the format of the <tt>Changes</tt> field see
9977 <ref id="f-Changes">.
9981 If the changelog format which is being parsed always or
9982 almost always leaves a blank line between individual
9983 change notes these blank lines should be stripped out,
9984 so as to make the resulting output compact.
9988 If the changelog format does not contain date or package
9989 name information this information should be omitted from
9990 the output. The parser should not attempt to synthesize
9991 it or find it from other sources.
9995 If the changelog does not have the expected format the
9996 parser should exit with a nonzero exit status, rather
9997 than trying to muddle through and possibly generating
10002 A changelog parser may not interact with the user at
10008 <sect1 id="pkg-srcsubstvars">
10009 <heading><file>debian/substvars</file> and variable substitutions</heading>
10012 See <ref id="substvars">.
10018 <heading><file>debian/files</file></heading>
10021 See <ref id="debianfiles">.
10025 <sect1><heading><file>debian/tmp</file>
10029 This is the canonical temporary location for the
10030 construction of binary packages by the <tt>binary</tt>
10031 target. The directory <file>tmp</file> serves as the root of
10032 the file system tree as it is being constructed (for
10033 example, by using the package's upstream makefiles install
10034 targets and redirecting the output there), and it also
10035 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10036 id="pkg-bincreating">.
10040 If several binary packages are generated from the same
10041 source tree it is usual to use several
10042 <file>debian/tmp<var>something</var></file> directories, for
10043 example <file>tmp-a</file> or <file>tmp-doc</file>.
10047 Whatever <file>tmp</file> directories are created and used by
10048 <tt>binary</tt> must of course be removed by the
10049 <tt>clean</tt> target.</p></sect1>
10053 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10057 As it exists on the FTP site, a Debian source package
10058 consists of three related files. You must have the right
10059 versions of all three to be able to use them.
10064 <tag>Debian source control file - <tt>.dsc</tt></tag>
10066 This file is a control file used by <prgn>dpkg-source</prgn>
10067 to extract a source package.
10068 See <ref id="debiansourcecontrolfiles">.
10072 Original source archive -
10074 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10080 This is a compressed (with <tt>gzip -9</tt>)
10081 <prgn>tar</prgn> file containing the source code from
10082 the upstream authors of the program.
10087 Debianisation diff -
10089 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10095 This is a unified context diff (<tt>diff -u</tt>)
10096 giving the changes which are required to turn the
10097 original source into the Debian source. These changes
10098 may only include editing and creating plain files.
10099 The permissions of files, the targets of symbolic
10100 links and the characteristics of special files or
10101 pipes may not be changed and no files may be removed
10106 All the directories in the diff must exist, except the
10107 <file>debian</file> subdirectory of the top of the source
10108 tree, which will be created by
10109 <prgn>dpkg-source</prgn> if necessary when unpacking.
10113 The <prgn>dpkg-source</prgn> program will
10114 automatically make the <file>debian/rules</file> file
10115 executable (see below).</p></item>
10120 If there is no original source code - for example, if the
10121 package is specially prepared for Debian or the Debian
10122 maintainer is the same as the upstream maintainer - the
10123 format is slightly different: then there is no diff, and the
10125 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10126 and preferably contains a directory named
10127 <file><var>package</var>-<var>version</var></file>.
10132 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10135 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10136 Debian source package. However, if it is not available it
10137 is possible to unpack a Debian source archive as follows:
10138 <enumlist compact="compact">
10141 Untar the tarfile, which will create a <file>.orig</file>
10145 <p>Rename the <file>.orig</file> directory to
10146 <file><var>package</var>-<var>version</var></file>.</p>
10150 Create the subdirectory <file>debian</file> at the top of
10151 the source tree.</p>
10153 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10155 <item><p>Untar the tarfile again if you want a copy of the original
10156 source code alongside the Debianised version.</p>
10161 It is not possible to generate a valid Debian source archive
10162 without using <prgn>dpkg-source</prgn>. In particular,
10163 attempting to use <prgn>diff</prgn> directly to generate the
10164 <file>.diff.gz</file> file will not work.
10168 <heading>Restrictions on objects in source packages</heading>
10171 The source package may not contain any hard links
10173 This is not currently detected when building source
10174 packages, but only when extracting
10178 Hard links may be permitted at some point in the
10179 future, but would require a fair amount of
10181 </footnote>, device special files, sockets or setuid or
10184 Setgid directories are allowed.
10189 The source packaging tools manage the changes between the
10190 original and Debianised source using <prgn>diff</prgn> and
10191 <prgn>patch</prgn>. Turning the original source tree as
10192 included in the <file>.orig.tar.gz</file> into the debianised
10193 source must not involve any changes which cannot be
10194 handled by these tools. Problematic changes which cause
10195 <prgn>dpkg-source</prgn> to halt with an error when
10196 building the source package are:
10197 <list compact="compact">
10198 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10200 <item><p>Changing the targets of symbolic links.</p>
10202 <item><p>Creating directories, other than <file>debian</file>.</p>
10204 <item><p>Changes to the contents of binary files.</p></item>
10205 </list> Changes which cause <prgn>dpkg-source</prgn> to
10206 print a warning but continue anyway are:
10207 <list compact="compact">
10210 Removing files, directories or symlinks.
10212 Renaming a file is not treated specially - it is
10213 seen as the removal of the old file (which
10214 generates a warning, but is otherwise ignored),
10215 and the creation of the new one.
10221 Changed text files which are missing the usual final
10222 newline (either in the original or the modified
10227 Changes which are not represented, but which are not detected by
10228 <prgn>dpkg-source</prgn>, are:
10229 <list compact="compact">
10230 <item><p>Changing the permissions of files (other than
10231 <file>debian/rules</file>) and directories.</p></item>
10236 The <file>debian</file> directory and <file>debian/rules</file>
10237 are handled specially by <prgn>dpkg-source</prgn> - before
10238 applying the changes it will create the <file>debian</file>
10239 directory, and afterwards it will make
10240 <file>debian/rules</file> world-executable.
10246 <appendix id="pkg-controlfields">
10247 <heading>Control files and their fields (from old Packaging Manual)</heading>
10250 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10251 data in a common format, known as control files. Binary and
10252 source packages have control data as do the <file>.changes</file>
10253 files which control the installation of uploaded files, and
10254 <prgn>dpkg</prgn>'s internal databases are in a similar
10259 <heading>Syntax of control files</heading>
10262 See <ref id="controlsyntax">.
10266 It is important to note that there are several fields which
10267 are optional as far as <prgn>dpkg</prgn> and the related
10268 tools are concerned, but which must appear in every Debian
10269 package, or whose omission may cause problems.
10274 <heading>List of fields</heading>
10277 See <ref id="controlfieldslist">.
10281 This section now contains only the fields that didn't belong
10282 to the Policy manual.
10285 <sect1 id="pkg-f-Filename">
10286 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10289 These fields in <tt>Packages</tt> files give the
10290 filename(s) of (the parts of) a package in the
10291 distribution directories, relative to the root of the
10292 Debian hierarchy. If the package has been split into
10293 several parts the parts are all listed in order, separated
10298 <sect1 id="pkg-f-Size">
10299 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10302 These fields in <file>Packages</file> files give the size (in
10303 bytes, expressed in decimal) and MD5 checksum of the
10304 file(s) which make(s) up a binary package in the
10305 distribution. If the package is split into several parts
10306 the values for the parts are listed in order, separated by
10311 <sect1 id="pkg-f-Status">
10312 <heading><tt>Status</tt></heading>
10315 This field in <prgn>dpkg</prgn>'s status file records
10316 whether the user wants a package installed, removed or
10317 left alone, whether it is broken (requiring
10318 re-installation) or not and what its current state on the
10319 system is. Each of these pieces of information is a
10324 <sect1 id="pkg-f-Config-Version">
10325 <heading><tt>Config-Version</tt></heading>
10328 If a package is not installed or not configured, this
10329 field in <prgn>dpkg</prgn>'s status file records the last
10330 version of the package which was successfully
10335 <sect1 id="pkg-f-Conffiles">
10336 <heading><tt>Conffiles</tt></heading>
10339 This field in <prgn>dpkg</prgn>'s status file contains
10340 information about the automatically-managed configuration
10341 files held by a package. This field should <em>not</em>
10342 appear anywhere in a package!
10347 <heading>Obsolete fields</heading>
10350 These are still recognized by <prgn>dpkg</prgn> but should
10351 not appear anywhere any more.
10353 <taglist compact="compact">
10355 <tag><tt>Revision</tt></tag>
10356 <tag><tt>Package-Revision</tt></tag>
10357 <tag><tt>Package_Revision</tt></tag>
10359 The Debian revision part of the package version was
10360 at one point in a separate control file field. This
10361 field went through several names.
10364 <tag><tt>Recommended</tt></tag>
10365 <item>Old name for <tt>Recommends</tt>.</item>
10367 <tag><tt>Optional</tt></tag>
10368 <item>Old name for <tt>Suggests</tt>.</item>
10370 <tag><tt>Class</tt></tag>
10371 <item>Old name for <tt>Priority</tt>.</item>
10380 <appendix id="pkg-conffiles">
10381 <heading>Configuration file handling (from old Packaging Manual)</heading>
10384 <prgn>dpkg</prgn> can do a certain amount of automatic
10385 handling of package configuration files.
10389 Whether this mechanism is appropriate depends on a number of
10390 factors, but basically there are two approaches to any
10391 particular configuration file.
10395 The easy method is to ship a best-effort configuration in the
10396 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10397 handle updates. If the user is unlikely to want to edit the
10398 file, but you need them to be able to without losing their
10399 changes, and a new package with a changed version of the file
10400 is only released infrequently, this is a good approach.
10404 The hard method is to build the configuration file from
10405 scratch in the <prgn>postinst</prgn> script, and to take the
10406 responsibility for fixing any mistakes made in earlier
10407 versions of the package automatically. This will be
10408 appropriate if the file is likely to need to be different on
10412 <sect><heading>Automatic handling of configuration files by
10417 A package may contain a control area file called
10418 <tt>conffiles</tt>. This file should be a list of filenames
10419 of configuration files needing automatic handling, separated
10420 by newlines. The filenames should be absolute pathnames,
10421 and the files referred to should actually exist in the
10426 When a package is upgraded <prgn>dpkg</prgn> will process
10427 the configuration files during the configuration stage,
10428 shortly before it runs the package's <prgn>postinst</prgn>
10433 For each file it checks to see whether the version of the
10434 file included in the package is the same as the one that was
10435 included in the last version of the package (the one that is
10436 being upgraded from); it also compares the version currently
10437 installed on the system with the one shipped with the last
10442 If neither the user nor the package maintainer has changed
10443 the file, it is left alone. If one or the other has changed
10444 their version, then the changed version is preferred - i.e.,
10445 if the user edits their file, but the package maintainer
10446 doesn't ship a different version, the user's changes will
10447 stay, silently, but if the maintainer ships a new version
10448 and the user hasn't edited it the new version will be
10449 installed (with an informative message). If both have
10450 changed their version the user is prompted about the problem
10451 and must resolve the differences themselves.
10455 The comparisons are done by calculating the MD5 message
10456 digests of the files, and storing the MD5 of the file as it
10457 was included in the most recent version of the package.
10461 When a package is installed for the first time
10462 <prgn>dpkg</prgn> will install the file that comes with it,
10463 unless that would mean overwriting a file already on the
10468 However, note that <prgn>dpkg</prgn> will <em>not</em>
10469 replace a conffile that was removed by the user (or by a
10470 script). This is necessary because with some programs a
10471 missing file produces an effect hard or impossible to
10472 achieve in another way, so that a missing file needs to be
10473 kept that way if the user did it.
10477 Note that a package should <em>not</em> modify a
10478 <prgn>dpkg</prgn>-handled conffile in its maintainer
10479 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10480 the user confusing and possibly dangerous options for
10481 conffile update when the package is upgraded.</p>
10484 <sect><heading>Fully-featured maintainer script configuration
10489 For files which contain site-specific information such as
10490 the hostname and networking details and so forth, it is
10491 better to create the file in the package's
10492 <prgn>postinst</prgn> script.
10496 This will typically involve examining the state of the rest
10497 of the system to determine values and other information, and
10498 may involve prompting the user for some information which
10499 can't be obtained some other way.
10503 When using this method there are a couple of important
10504 issues which should be considered:
10508 If you discover a bug in the program which generates the
10509 configuration file, or if the format of the file changes
10510 from one version to the next, you will have to arrange for
10511 the postinst script to do something sensible - usually this
10512 will mean editing the installed configuration file to remove
10513 the problem or change the syntax. You will have to do this
10514 very carefully, since the user may have changed the file,
10515 perhaps to fix the very problem that your script is trying
10516 to deal with - you will have to detect these situations and
10517 deal with them correctly.
10521 If you do go down this route it's probably a good idea to
10522 make the program that generates the configuration file(s) a
10523 separate program in <file>/usr/sbin</file>, by convention called
10524 <file><var>package</var>config</file> and then run that if
10525 appropriate from the post-installation script. The
10526 <tt><var>package</var>config</tt> program should not
10527 unquestioningly overwrite an existing configuration - if its
10528 mode of operation is geared towards setting up a package for
10529 the first time (rather than any arbitrary reconfiguration
10530 later) you should have it check whether the configuration
10531 already exists, and require a <tt>--force</tt> flag to
10532 overwrite it.</p></sect>
10535 <appendix id="pkg-alternatives"><heading>Alternative versions of
10536 an interface - <prgn>update-alternatives</prgn> (from old
10541 When several packages all provide different versions of the
10542 same program or file it is useful to have the system select a
10543 default, but to allow the system administrator to change it
10544 and have their decisions respected.
10548 For example, there are several versions of the <prgn>vi</prgn>
10549 editor, and there is no reason to prevent all of them from
10550 being installed at once, each under their own name
10551 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10552 Nevertheless it is desirable to have the name <tt>vi</tt>
10553 refer to something, at least by default.
10557 If all the packages involved cooperate, this can be done with
10558 <prgn>update-alternatives</prgn>.
10562 Each package provides its own version under its own name, and
10563 calls <prgn>update-alternatives</prgn> in its postinst to
10564 register its version (and again in its prerm to deregister
10569 See the man page <manref name="update-alternatives"
10570 section="8"> for details.
10574 If <prgn>update-alternatives</prgn> does not seem appropriate
10575 you may wish to consider using diversions instead.</p>
10578 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10579 package's version of a file (from old Packaging Manual)
10583 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10584 when it reinstalls the package it belongs to, and to have it
10585 put the file from the package somewhere else instead.
10589 This can be used locally to override a package's version of a
10590 file, or by one package to override another's version (or
10591 provide a wrapper for it).
10595 Before deciding to use a diversion, read <ref
10596 id="pkg-alternatives"> to see if you really want a diversion
10597 rather than several alternative versions of a program.
10601 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10602 and updated by a special program <prgn>dpkg-divert</prgn>.
10603 Please see <manref name="dpkg-divert" section="8"> for full
10604 details of its operation.
10608 When a package wishes to divert a file from another, it should
10609 call <prgn>dpkg-divert</prgn> in its preinst to add the
10610 diversion and rename the existing file. For example,
10611 supposing that a <prgn>smailwrapper</prgn> package wishes to
10612 install a wrapper around <file>/usr/sbin/smail</file>:
10614 dpkg-divert --package smailwrapper --add --rename \
10615 --divert /usr/sbin/smail.real /usr/sbin/smail
10616 </example> The <tt>--package smailwrapper</tt> ensures that
10617 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10618 can bypass the diversion and get installed as the true version.
10619 It's safe to add the diversion unconditionally on upgrades since
10620 it will be left unchanged if it already exists, but
10621 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10622 message, make the command conditional on the version from which
10623 the package is being upgraded:
10625 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10626 dpkg-divert --package smailwrapper --add --rename \
10627 --divert /usr/sbin/smail.real /usr/sbin/smail
10629 </example> where <tt>1.0-2</tt> is the version at which the
10630 diversion was first added to the package. Running the command
10631 during abort-upgrade is pointless but harmless.
10635 The postrm has to do the reverse:
10637 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10638 dpkg-divert --package smailwrapper --remove --rename \
10639 --divert /usr/sbin/smail.real /usr/sbin/smail
10641 </example> If the diversion was added at a particular version, the
10642 postrm should also handle the failure case of upgrading from an
10643 older version (unless the older version is so old that direct
10644 upgrades are no longer supported):
10646 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10647 dpkg-divert --package smailwrapper --remove --rename \
10648 --divert /usr/sbin/smail.real /usr/sbin/smail
10650 </example> where <tt>1.02-2</tt> is the version at which the
10651 diversion was first added to the package. The postrm should not
10652 remove the diversion on upgrades both because there's no reason to
10653 remove the diversion only to immediately re-add it and since the
10654 postrm of the old package is run after unpacking so the removal of
10655 the diversion will fail.
10659 Do not attempt to divert a file which is vitally important for
10660 the system's operation - when using <prgn>dpkg-divert</prgn>
10661 there is a time, after it has been diverted but before
10662 <prgn>dpkg</prgn> has installed the new version, when the file
10663 does not exist.</p>
10668 <!-- Local variables: -->
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