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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.
2382 Field values are case-sensitive unless the description of the
2383 field says otherwise.
2387 Blank lines, or lines consisting only of spaces and tabs,
2388 are not allowed within field values or between fields - that
2389 would mean a new paragraph.
2393 All control files must be encoded in UTF-8.
2397 <sect id="sourcecontrolfiles">
2398 <heading>Source package control files -- <file>debian/control</file></heading>
2401 The <file>debian/control</file> file contains the most vital
2402 (and version-independent) information about the source package
2403 and about the binary packages it creates.
2407 The first paragraph of the control file contains information about
2408 the source package in general. The subsequent sets each describe a
2409 binary package that the source tree builds.
2413 The fields in the general paragraph (the first one, for the source
2416 <list compact="compact">
2417 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2418 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2419 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2420 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2421 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2422 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2423 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2424 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2429 The fields in the binary package paragraphs are:
2431 <list compact="compact">
2432 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2433 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2434 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2435 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2436 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2437 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2438 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2439 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2444 The syntax and semantics of the fields are described below.
2450 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2451 generate control files for binary packages (see below), by
2452 <prgn>dpkg-genchanges</prgn> to generate the
2453 <tt>.changes</tt> file to accompany the upload, and by
2454 <prgn>dpkg-source</prgn> when it creates the
2455 <file>.dsc</file> source control file as part of a source
2456 archive. Many fields are permitted to span multiple lines in
2457 <file>debian/control</file> but not in any other control
2458 file. These tools are responsible for removing the line
2459 breaks from such fields when using fields from
2460 <file>debian/control</file> to generate other control files.
2464 The fields here may contain variable references - their
2465 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2466 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2467 when they generate output control files.
2468 See <ref id="substvars"> for details.
2472 In addition to the control file syntax described <qref
2473 id="controlsyntax">above</qref>, this file may also contain
2474 comment lines starting with <tt>#</tt> without any preceding
2475 whitespace. All such lines are ignored, even in the middle of
2476 continuation lines for a multiline field, and do not end a
2482 <sect id="binarycontrolfiles">
2483 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2486 The <file>DEBIAN/control</file> file contains the most vital
2487 (and version-dependent) information about a binary package.
2491 The fields in this file are:
2493 <list compact="compact">
2494 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2495 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2496 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2497 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2498 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2499 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2500 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2501 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2502 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2503 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2504 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2505 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2510 <sect id="debiansourcecontrolfiles">
2511 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2514 This file contains a series of fields, identified and
2515 separated just like the fields in the control file of
2516 a binary package. The fields are listed below; their
2517 syntax is described above, in <ref id="pkg-controlfields">.
2519 <list compact="compact">
2520 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2522 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2523 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2524 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2525 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2526 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2527 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2528 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2529 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2530 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2535 The source package control file is generated by
2536 <prgn>dpkg-source</prgn> when it builds the source
2537 archive, from other files in the source package,
2538 described above. When unpacking, it is checked against
2539 the files and directories in the other parts of the
2545 <sect id="debianchangesfiles">
2546 <heading>Debian changes files -- <file>.changes</file></heading>
2549 The .changes files are used by the Debian archive maintenance
2550 software to process updates to packages. They contain one
2551 paragraph which contains information from the
2552 <tt>debian/control</tt> file and other data about the
2553 source package gathered via <tt>debian/changelog</tt>
2554 and <tt>debian/rules</tt>.
2558 The fields in this file are:
2560 <list compact="compact">
2561 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2562 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2563 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2564 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2569 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2570 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2571 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2573 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2574 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2579 <sect id="controlfieldslist">
2580 <heading>List of fields</heading>
2582 <sect1 id="f-Source">
2583 <heading><tt>Source</tt></heading>
2586 This field identifies the source package name.
2590 In <file>debian/control</file> or a <file>.dsc</file> file,
2591 this field must contain only the name of the source package.
2595 In a binary package control file or a <file>.changes</file>
2596 file, the source package name may be followed by a version
2597 number in parentheses<footnote>
2598 It is customary to leave a space after the package name
2599 if a version number is specified.
2601 This version number may be omitted (and is, by
2602 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2603 the <tt>Version</tt> field of the binary package in
2604 question. The field itself may be omitted from a binary
2605 package control file when the source package has the same
2606 name and version as the binary package.
2610 Package names (both source and binary,
2611 see <ref id="f-Package">) must consist only of lower case
2612 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2613 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2614 (<tt>.</tt>). They must be at least two characters long and
2615 must start with an alphanumeric character.
2619 <sect1 id="f-Maintainer">
2620 <heading><tt>Maintainer</tt></heading>
2623 The package maintainer's name and email address. The name
2624 should come first, then the email address inside angle
2625 brackets <tt><></tt> (in RFC822 format).
2629 If the maintainer's name contains a full stop then the
2630 whole field will not work directly as an email address due
2631 to a misfeature in the syntax specified in RFC822; a
2632 program using this field as an address must check for this
2633 and correct the problem if necessary (for example by
2634 putting the name in round brackets and moving it to the
2635 end, and bringing the email address forward).
2639 <sect1 id="f-Uploaders">
2640 <heading><tt>Uploaders</tt></heading>
2643 List of the names and email addresses of co-maintainers of
2644 the package, if any. If the package has other maintainers
2645 beside the one named in the
2646 <qref id="f-Maintainer">Maintainer field</qref>, their
2647 names and email addresses should be listed here. The
2648 format is the same as that of the Maintainer tag, and
2649 multiple entries should be comma separated. Currently,
2650 this field is restricted to a single line of data. This
2651 is an optional field.
2654 Any parser that interprets the Uploaders field in
2655 <file>debian/control</file> must permit it to span multiple
2656 lines. Line breaks in an Uploaders field that spans multiple
2657 lines are not significant and the semantics of the field are
2658 the same as if the line breaks had not been present.
2662 <sect1 id="f-Changed-By">
2663 <heading><tt>Changed-By</tt></heading>
2666 The name and email address of the person who changed the
2667 said package. Usually the name of the maintainer.
2668 All the rules for the Maintainer field apply here, too.
2672 <sect1 id="f-Section">
2673 <heading><tt>Section</tt></heading>
2676 This field specifies an application area into which the package
2677 has been classified. See <ref id="subsections">.
2681 When it appears in the <file>debian/control</file> file,
2682 it gives the value for the subfield of the same name in
2683 the <tt>Files</tt> field of the <file>.changes</file> file.
2684 It also gives the default for the same field in the binary
2689 <sect1 id="f-Priority">
2690 <heading><tt>Priority</tt></heading>
2693 This field represents how important that it is that the user
2694 have the package installed. See <ref id="priorities">.
2698 When it appears in the <file>debian/control</file> file,
2699 it gives the value for the subfield of the same name in
2700 the <tt>Files</tt> field of the <file>.changes</file> file.
2701 It also gives the default for the same field in the binary
2706 <sect1 id="f-Package">
2707 <heading><tt>Package</tt></heading>
2710 The name of the binary package.
2714 Binary package names must follow the same syntax and
2715 restrictions as source package names. See <ref id="f-Source">
2720 <sect1 id="f-Architecture">
2721 <heading><tt>Architecture</tt></heading>
2724 Depending on context and the control file used, the
2725 <tt>Architecture</tt> field can include the following sets of
2728 <item>A unique single word identifying a Debian machine
2729 architecture as described in <ref id="arch-spec">.
2730 <item><tt>all</tt>, which indicates an
2731 architecture-independent package.
2732 <item><tt>any</tt>, which indicates a package available
2733 for building on any architecture.
2734 <item><tt>source</tt>, which indicates a source package.
2739 In the main <file>debian/control</file> file in the source
2740 package, this field may contain the special value
2741 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2742 architectures separated by spaces. If <tt>any</tt> or
2743 <tt>all</tt> appear, they must be the entire contents of the
2744 field. Most packages will use either <tt>any</tt> or
2745 <tt>all</tt>. Specifying a specific list of architectures is
2746 for the minority of cases where a program is not portable or
2747 is not useful on some architectures, and where possible the
2748 program should be made portable instead.
2752 In the source package control file <file>.dsc</file>, this
2753 field may contain either the special value <tt>any</tt> or a
2754 list of architectures separated by spaces. If a list is given,
2755 it may include (or consist solely of) the special value
2756 <tt>all</tt>. In other words, in <file>.dsc</file> files
2757 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2758 in combination with specific architectures. The
2759 <tt>Architecture</tt> field in the source package control file
2760 <file>.dsc</file> is generally constructed from the
2761 <tt>Architecture</tt> fields in the
2762 <file>debian/control</file> in the source package.
2766 Specifying <tt>any</tt> indicates that the source package
2767 isn't dependent on any particular architecture and should
2768 compile fine on any one. The produced binary package(s)
2769 will either be specific to whatever the current build
2770 architecture is or will be architecture-independent.
2774 Specifying only <tt>all</tt> indicates that the source package
2775 will only build architecture-independent packages. If this is
2776 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2777 <tt>any</tt> implies that the source package will build at
2778 least one architecture-dependent package.
2782 Specifying a list of architectures indicates that the source
2783 will build an architecture-dependent package, and will only
2784 work correctly on the listed architectures. If the source
2785 package also builds at least one architecture-independent
2786 package, <tt>all</tt> will also be included in the list.
2790 In a <file>.changes</file> file, the <tt>Architecture</tt>
2791 field lists the architecture(s) of the package(s)
2792 currently being uploaded. This will be a list; if the
2793 source for the package is also being uploaded, the special
2794 entry <tt>source</tt> is also present. <tt>all</tt> will be
2795 present if any architecture-independent packages are being
2796 uploaded. <tt>any</tt> may never occur in the
2797 <tt>Architecture</tt> field in the <file>.changes</file>
2802 See <ref id="debianrules"> for information how to get the
2803 architecture for the build process.
2807 <sect1 id="f-Essential">
2808 <heading><tt>Essential</tt></heading>
2811 This is a boolean field which may occur only in the
2812 control file of a binary package or in a per-package fields
2813 paragraph of a main source control data file.
2817 If set to <tt>yes</tt> then the package management system
2818 will refuse to remove the package (upgrading and replacing
2819 it is still possible). The other possible value is <tt>no</tt>,
2820 which is the same as not having the field at all.
2825 <heading>Package interrelationship fields:
2826 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2827 <tt>Recommends</tt>, <tt>Suggests</tt>,
2828 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2829 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2833 These fields describe the package's relationships with
2834 other packages. Their syntax and semantics are described
2835 in <ref id="relationships">.</p>
2838 <sect1 id="f-Standards-Version">
2839 <heading><tt>Standards-Version</tt></heading>
2842 The most recent version of the standards (the policy
2843 manual and associated texts) with which the package
2848 The version number has four components: major and minor
2849 version number and major and minor patch level. When the
2850 standards change in a way that requires every package to
2851 change the major number will be changed. Significant
2852 changes that will require work in many packages will be
2853 signaled by a change to the minor number. The major patch
2854 level will be changed for any change to the meaning of the
2855 standards, however small; the minor patch level will be
2856 changed when only cosmetic, typographical or other edits
2857 are made which neither change the meaning of the document
2858 nor affect the contents of packages.
2862 Thus only the first three components of the policy version
2863 are significant in the <em>Standards-Version</em> control
2864 field, and so either these three components or the all
2865 four components may be specified.<footnote>
2866 In the past, people specified the full version number
2867 in the Standards-Version field, for example "2.3.0.0".
2868 Since minor patch-level changes don't introduce new
2869 policy, it was thought it would be better to relax
2870 policy and only require the first 3 components to be
2871 specified, in this example "2.3.0". All four
2872 components may still be used if someone wishes to do so.
2878 <sect1 id="f-Version">
2879 <heading><tt>Version</tt></heading>
2882 The version number of a package. The format is:
2883 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2887 The three components here are:
2889 <tag><var>epoch</var></tag>
2892 This is a single (generally small) unsigned integer. It
2893 may be omitted, in which case zero is assumed. If it is
2894 omitted then the <var>upstream_version</var> may not
2899 It is provided to allow mistakes in the version numbers
2900 of older versions of a package, and also a package's
2901 previous version numbering schemes, to be left behind.
2905 <tag><var>upstream_version</var></tag>
2908 This is the main part of the version number. It is
2909 usually the version number of the original ("upstream")
2910 package from which the <file>.deb</file> file has been made,
2911 if this is applicable. Usually this will be in the same
2912 format as that specified by the upstream author(s);
2913 however, it may need to be reformatted to fit into the
2914 package management system's format and comparison
2919 The comparison behavior of the package management system
2920 with respect to the <var>upstream_version</var> is
2921 described below. The <var>upstream_version</var>
2922 portion of the version number is mandatory.
2926 The <var>upstream_version</var> may contain only
2927 alphanumerics<footnote>
2928 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2930 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2931 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2932 tilde) and should start with a digit. If there is no
2933 <var>debian_revision</var> then hyphens are not allowed;
2934 if there is no <var>epoch</var> then colons are not
2939 <tag><var>debian_revision</var></tag>
2942 This part of the version number specifies the version of
2943 the Debian package based on the upstream version. It
2944 may contain only alphanumerics and the characters
2945 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2946 tilde) and is compared in the same way as the
2947 <var>upstream_version</var> is.
2951 It is optional; if it isn't present then the
2952 <var>upstream_version</var> may not contain a hyphen.
2953 This format represents the case where a piece of
2954 software was written specifically to be turned into a
2955 Debian package, and so there is only one "debianisation"
2956 of it and therefore no revision indication is required.
2960 It is conventional to restart the
2961 <var>debian_revision</var> at <tt>1</tt> each time the
2962 <var>upstream_version</var> is increased.
2966 The package management system will break the version
2967 number apart at the last hyphen in the string (if there
2968 is one) to determine the <var>upstream_version</var> and
2969 <var>debian_revision</var>. The absence of a
2970 <var>debian_revision</var> is equivalent to a
2971 <var>debian_revision</var> of <tt>0</tt>.
2978 When comparing two version numbers, first the <var>epoch</var>
2979 of each are compared, then the <var>upstream_version</var> if
2980 <var>epoch</var> is equal, and then <var>debian_revision</var>
2981 if <var>upstream_version</var> is also equal.
2982 <var>epoch</var> is compared numerically. The
2983 <var>upstream_version</var> and <var>debian_revision</var>
2984 parts are compared by the package management system using the
2985 following algorithm:
2989 The strings are compared from left to right.
2993 First the initial part of each string consisting entirely of
2994 non-digit characters is determined. These two parts (one of
2995 which may be empty) are compared lexically. If a difference
2996 is found it is returned. The lexical comparison is a
2997 comparison of ASCII values modified so that all the letters
2998 sort earlier than all the non-letters and so that a tilde
2999 sorts before anything, even the end of a part. For example,
3000 the following parts are in sorted order from earliest to
3001 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3002 <tt>a</tt>.<footnote>
3003 One common use of <tt>~</tt> is for upstream pre-releases.
3004 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3005 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3010 Then the initial part of the remainder of each string which
3011 consists entirely of digit characters is determined. The
3012 numerical values of these two parts are compared, and any
3013 difference found is returned as the result of the comparison.
3014 For these purposes an empty string (which can only occur at
3015 the end of one or both version strings being compared) counts
3020 These two steps (comparing and removing initial non-digit
3021 strings and initial digit strings) are repeated until a
3022 difference is found or both strings are exhausted.
3026 Note that the purpose of epochs is to allow us to leave behind
3027 mistakes in version numbering, and to cope with situations
3028 where the version numbering scheme changes. It is
3029 <em>not</em> intended to cope with version numbers containing
3030 strings of letters which the package management system cannot
3031 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3032 silly orderings (the author of this manual has heard of a
3033 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3034 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3035 <tt>2</tt> and so forth).
3039 <sect1 id="f-Description">
3040 <heading><tt>Description</tt></heading>
3043 In a source or binary control file, the <tt>Description</tt>
3044 field contains a description of the binary package, consisting
3045 of two parts, the synopsis or the short description, and the
3046 long description. The field's format is as follows:
3051 Description: <single line synopsis>
3052 <extended description over several lines>
3057 The lines in the extended description can have these formats:
3063 Those starting with a single space are part of a paragraph.
3064 Successive lines of this form will be word-wrapped when
3065 displayed. The leading space will usually be stripped off.
3069 Those starting with two or more spaces. These will be
3070 displayed verbatim. If the display cannot be panned
3071 horizontally, the displaying program will line wrap them "hard"
3072 (i.e., without taking account of word breaks). If it can they
3073 will be allowed to trail off to the right. None, one or two
3074 initial spaces may be deleted, but the number of spaces
3075 deleted from each line will be the same (so that you can have
3076 indenting work correctly, for example).
3080 Those containing a single space followed by a single full stop
3081 character. These are rendered as blank lines. This is the
3082 <em>only</em> way to get a blank line<footnote>
3083 Completely empty lines will not be rendered as blank lines.
3084 Instead, they will cause the parser to think you're starting
3085 a whole new record in the control file, and will therefore
3086 likely abort with an error.
3091 Those containing a space, a full stop and some more characters.
3092 These are for future expansion. Do not use them.
3098 Do not use tab characters. Their effect is not predictable.
3102 See <ref id="descriptions"> for further information on this.
3106 In a <file>.changes</file> file, the <tt>Description</tt>
3107 field contains a summary of the descriptions for the packages
3108 being uploaded. For this case, the first line of the field
3109 value (the part on the same line as <tt>Description:</tt>) is
3110 always empty. The content of the field is expressed as
3111 continuation lines, one line per package. Each line is
3112 indented by one space and contains the name of a binary
3113 package, a space, a hyphen (<tt>-</tt>), a space, and the
3114 short description line from that package.
3118 <sect1 id="f-Distribution">
3119 <heading><tt>Distribution</tt></heading>
3122 In a <file>.changes</file> file or parsed changelog output
3123 this contains the (space-separated) name(s) of the
3124 distribution(s) where this version of the package should
3125 be installed. Valid distributions are determined by the
3126 archive maintainers.<footnote>
3127 Example distribution names in the Debian archive used in
3128 <file>.changes</file> files are:
3129 <taglist compact="compact">
3130 <tag><em>unstable</em></tag>
3132 This distribution value refers to the
3133 <em>developmental</em> part of the Debian distribution
3134 tree. Most new packages, new upstream versions of
3135 packages and bug fixes go into the <em>unstable</em>
3139 <tag><em>experimental</em></tag>
3141 The packages with this distribution value are deemed
3142 by their maintainers to be high risk. Oftentimes they
3143 represent early beta or developmental packages from
3144 various sources that the maintainers want people to
3145 try, but are not ready to be a part of the other parts
3146 of the Debian distribution tree.
3151 Others are used for updating stable releases or for
3152 security uploads. More information is available in the
3153 Debian Developer's Reference, section "The Debian
3157 The Debian archive software only supports listing a single
3158 distribution. Migration of packages to other distributions is
3159 handled outside of the upload process.
3164 <heading><tt>Date</tt></heading>
3167 This field includes the date the package was built or last edited.
3171 The value of this field is usually extracted from the
3172 <file>debian/changelog</file> file - see
3173 <ref id="dpkgchangelog">).
3177 <sect1 id="f-Format">
3178 <heading><tt>Format</tt></heading>
3181 This field specifies a format revision for the file.
3182 The most current format described in the Policy Manual
3183 is version <strong>1.5</strong>. The syntax of the
3184 format value is the same as that of a package version
3185 number except that no epoch or Debian revision is allowed
3186 - see <ref id="f-Version">.
3190 <sect1 id="f-Urgency">
3191 <heading><tt>Urgency</tt></heading>
3194 This is a description of how important it is to upgrade to
3195 this version from previous ones. It consists of a single
3196 keyword taking one of the values <tt>low</tt>,
3197 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3198 <tt>critical</tt><footnote>
3199 Other urgency values are supported with configuration
3200 changes in the archive software but are not used in Debian.
3201 The urgency affects how quickly a package will be considered
3202 for inclusion into the <tt>testing</tt> distribution and
3203 gives an indication of the importance of any fixes included
3204 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3205 treated as synonymous.
3206 </footnote> (not case-sensitive) followed by an optional
3207 commentary (separated by a space) which is usually in
3208 parentheses. For example:
3211 Urgency: low (HIGH for users of diversions)
3217 The value of this field is usually extracted from the
3218 <file>debian/changelog</file> file - see
3219 <ref id="dpkgchangelog">.
3223 <sect1 id="f-Changes">
3224 <heading><tt>Changes</tt></heading>
3227 This field contains the human-readable changes data, describing
3228 the differences between the last version and the current one.
3232 The first line of the field value (the part on the same line
3233 as <tt>Changes:</tt>) is always empty. The content of the
3234 field is expressed as continuation lines, with each line
3235 indented by at least one space. Blank lines must be
3236 represented by a line consisting only of a space and a full
3241 The value of this field is usually extracted from the
3242 <file>debian/changelog</file> file - see
3243 <ref id="dpkgchangelog">).
3247 Each version's change information should be preceded by a
3248 "title" line giving at least the version, distribution(s)
3249 and urgency, in a human-readable way.
3253 If data from several versions is being returned the entry
3254 for the most recent version should be returned first, and
3255 entries should be separated by the representation of a
3256 blank line (the "title" line may also be followed by the
3257 representation of blank line).
3261 <sect1 id="f-Binary">
3262 <heading><tt>Binary</tt></heading>
3265 This field is a list of binary packages. Its syntax and
3266 meaning varies depending on the control file in which it
3271 When it appears in the <file>.dsc</file> file, it lists binary
3272 packages which a source package can produce, separated by
3274 A space after each comma is conventional.
3275 </footnote>. It may span multiple lines. The source package
3276 does not necessarily produce all of these binary packages for
3277 every architecture. The source control file doesn't contain
3278 details of which architectures are appropriate for which of
3279 the binary packages.
3283 When it appears in a <file>.changes</file> file, it lists the
3284 names of the binary packages being uploaded, separated by
3285 whitespace (not commas). It may span multiple lines.
3289 <sect1 id="f-Installed-Size">
3290 <heading><tt>Installed-Size</tt></heading>
3293 This field appears in the control files of binary packages,
3294 and in the <file>Packages</file> files. It gives an estimate
3295 of the total amount of disk space required to install the
3296 named package. Actual installed size may vary based on block
3297 size, file system properties, or actions taken by package
3302 The disk space is given as the integer value of the estimated
3303 installed size in bytes, divided by 1024 and rounded up.
3307 <sect1 id="f-Files">
3308 <heading><tt>Files</tt></heading>
3311 This field contains a list of files with information about
3312 each one. The exact information and syntax varies with
3317 In all cases, Files is a multiline field. The first line of
3318 the field value (the part on the same line as <tt>Files:</tt>)
3319 is always empty. The content of the field is expressed as
3320 continuation lines, one line per file. Each line must be
3321 indented by one space and contain a number of sub-fields,
3322 separated by spaces, as described below.
3326 In the <file>.dsc</file> file, each line contains the MD5
3327 checksum, size and filename of the tar file and (if
3328 applicable) diff file which make up the remainder of the
3329 source package<footnote>
3330 That is, the parts which are not the <tt>.dsc</tt>.
3331 </footnote>. For example:
3334 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3335 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3337 The exact forms of the filenames are described
3338 in <ref id="pkg-sourcearchives">.
3342 In the <file>.changes</file> file this contains one line per
3343 file being uploaded. Each line contains the MD5 checksum,
3344 size, section and priority and the filename. For example:
3347 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3348 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3349 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3350 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3352 The <qref id="f-Section">section</qref>
3353 and <qref id="f-Priority">priority</qref> are the values of
3354 the corresponding fields in the main source control file. If
3355 no section or priority is specified then <tt>-</tt> should be
3356 used, though section and priority values must be specified for
3357 new packages to be installed properly.
3361 The special value <tt>byhand</tt> for the section in a
3362 <tt>.changes</tt> file indicates that the file in question
3363 is not an ordinary package file and must by installed by
3364 hand by the distribution maintainers. If the section is
3365 <tt>byhand</tt> the priority should be <tt>-</tt>.
3369 If a new Debian revision of a package is being shipped and
3370 no new original source archive is being distributed the
3371 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3372 entry for the original source archive
3373 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3374 but the <file>.changes</file> file should leave it out. In
3375 this case the original source archive on the distribution
3376 site must match exactly, byte-for-byte, the original
3377 source archive which was used to generate the
3378 <file>.dsc</file> file and diff which are being uploaded.</p>
3381 <sect1 id="f-Closes">
3382 <heading><tt>Closes</tt></heading>
3385 A space-separated list of bug report numbers that the upload
3386 governed by the .changes file closes.
3390 <sect1 id="f-Homepage">
3391 <heading><tt>Homepage</tt></heading>
3394 The URL of the web site for this package, preferably (when
3395 applicable) the site from which the original source can be
3396 obtained and any additional upstream documentation or
3397 information may be found. The content of this field is a
3398 simple URL without any surrounding characters such as
3406 <heading>User-defined fields</heading>
3409 Additional user-defined fields may be added to the
3410 source package control file. Such fields will be
3411 ignored, and not copied to (for example) binary or
3412 source package control files or upload control files.
3416 If you wish to add additional unsupported fields to
3417 these output files you should use the mechanism
3422 Fields in the main source control information file with
3423 names starting <tt>X</tt>, followed by one or more of
3424 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3425 be copied to the output files. Only the part of the
3426 field name after the hyphen will be used in the output
3427 file. Where the letter <tt>B</tt> is used the field
3428 will appear in binary package control files, where the
3429 letter <tt>S</tt> is used in source package control
3430 files and where <tt>C</tt> is used in upload control
3431 (<tt>.changes</tt>) files.
3435 For example, if the main source information control file
3438 XBS-Comment: I stand between the candle and the star.
3440 then the binary and source package control files will contain the
3443 Comment: I stand between the candle and the star.
3452 <chapt id="maintainerscripts">
3453 <heading>Package maintainer scripts and installation procedure</heading>
3456 <heading>Introduction to package maintainer scripts</heading>
3459 It is possible to supply scripts as part of a package which
3460 the package management system will run for you when your
3461 package is installed, upgraded or removed.
3465 These scripts are the files <prgn>preinst</prgn>,
3466 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3467 <prgn>postrm</prgn> in the control area of the package.
3468 They must be proper executable files; if they are scripts
3469 (which is recommended), they must start with the usual
3470 <tt>#!</tt> convention. They should be readable and
3471 executable by anyone, and must not be world-writable.
3475 The package management system looks at the exit status from
3476 these scripts. It is important that they exit with a
3477 non-zero status if there is an error, so that the package
3478 management system can stop its processing. For shell
3479 scripts this means that you <em>almost always</em> need to
3480 use <tt>set -e</tt> (this is usually true when writing shell
3481 scripts, in fact). It is also important, of course, that
3482 they exit with a zero status if everything went well.
3486 Additionally, packages interacting with users using
3487 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3488 install a <prgn>config</prgn> script in the control area,
3489 see <ref id="maintscriptprompt"> for details.
3493 When a package is upgraded a combination of the scripts from
3494 the old and new packages is called during the upgrade
3495 procedure. If your scripts are going to be at all
3496 complicated you need to be aware of this, and may need to
3497 check the arguments to your scripts.
3501 Broadly speaking the <prgn>preinst</prgn> is called before
3502 (a particular version of) a package is installed, and the
3503 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3504 before (a version of) a package is removed and the
3505 <prgn>postrm</prgn> afterwards.
3509 Programs called from maintainer scripts should not normally
3510 have a path prepended to them. Before installation is
3511 started, the package management system checks to see if the
3512 programs <prgn>ldconfig</prgn>,
3513 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3514 and <prgn>update-rc.d</prgn> can be found via the
3515 <tt>PATH</tt> environment variable. Those programs, and any
3516 other program that one would expect to be in the
3517 <tt>PATH</tt>, should thus be invoked without an absolute
3518 pathname. Maintainer scripts should also not reset the
3519 <tt>PATH</tt>, though they might choose to modify it by
3520 prepending or appending package-specific directories. These
3521 considerations really apply to all shell scripts.</p>
3524 <sect id="idempotency">
3525 <heading>Maintainer scripts idempotency</heading>
3528 It is necessary for the error recovery procedures that the
3529 scripts be idempotent. This means that if it is run
3530 successfully, and then it is called again, it doesn't bomb
3531 out or cause any harm, but just ensures that everything is
3532 the way it ought to be. If the first call failed, or
3533 aborted half way through for some reason, the second call
3534 should merely do the things that were left undone the first
3535 time, if any, and exit with a success status if everything
3537 This is so that if an error occurs, the user interrupts
3538 <prgn>dpkg</prgn> or some other unforeseen circumstance
3539 happens you don't leave the user with a badly-broken
3540 package when <prgn>dpkg</prgn> attempts to repeat the
3546 <sect id="controllingterminal">
3547 <heading>Controlling terminal for maintainer scripts</heading>
3550 Maintainer scripts are not guaranteed to run with a controlling
3551 terminal and may not be able to interact with the user. They
3552 must be able to fall back to noninteractive behavior if no
3553 controlling terminal is available. Maintainer scripts that
3554 prompt via a program conforming to the Debian Configuration
3555 Management Specification (see <ref id="maintscriptprompt">) may
3556 assume that program will handle falling back to noninteractive
3561 <sect id="exitstatus">
3562 <heading>Exit status</heading>
3565 Each script must return a zero exit status for
3566 success, or a nonzero one for failure, since the package
3567 management system looks for the exit status of these scripts
3568 and determines what action to take next based on that datum.
3572 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3577 <list compact="compact">
3579 <var>new-preinst</var> <tt>install</tt>
3582 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3585 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3588 <var>old-preinst</var> <tt>abort-upgrade</tt>
3589 <var>new-version</var>
3594 <list compact="compact">
3596 <var>postinst</var> <tt>configure</tt>
3597 <var>most-recently-configured-version</var>
3600 <var>old-postinst</var> <tt>abort-upgrade</tt>
3601 <var>new-version</var>
3604 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3605 <tt>in-favour</tt> <var>package</var>
3606 <var>new-version</var>
3609 <var>postinst</var> <tt>abort-remove</tt>
3612 <var>deconfigured's-postinst</var>
3613 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3614 <var>failed-install-package</var> <var>version</var>
3615 [<tt>removing</tt> <var>conflicting-package</var>
3621 <list compact="compact">
3623 <var>prerm</var> <tt>remove</tt>
3626 <var>old-prerm</var> <tt>upgrade</tt>
3627 <var>new-version</var>
3630 <var>new-prerm</var> <tt>failed-upgrade</tt>
3631 <var>old-version</var>
3634 <var>conflictor's-prerm</var> <tt>remove</tt>
3635 <tt>in-favour</tt> <var>package</var>
3636 <var>new-version</var>
3639 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3640 <tt>in-favour</tt> <var>package-being-installed</var>
3641 <var>version</var> [<tt>removing</tt>
3642 <var>conflicting-package</var>
3648 <list compact="compact">
3650 <var>postrm</var> <tt>remove</tt>
3653 <var>postrm</var> <tt>purge</tt>
3656 <var>old-postrm</var> <tt>upgrade</tt>
3657 <var>new-version</var>
3660 <var>new-postrm</var> <tt>failed-upgrade</tt>
3661 <var>old-version</var>
3664 <var>new-postrm</var> <tt>abort-install</tt>
3667 <var>new-postrm</var> <tt>abort-install</tt>
3668 <var>old-version</var>
3671 <var>new-postrm</var> <tt>abort-upgrade</tt>
3672 <var>old-version</var>
3675 <var>disappearer's-postrm</var> <tt>disappear</tt>
3676 <var>overwriter</var>
3677 <var>overwriter-version</var>
3683 <sect id="unpackphase">
3684 <heading>Details of unpack phase of installation or upgrade</heading>
3687 The procedure on installation/upgrade/overwrite/disappear
3688 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3689 stage of <tt>dpkg --install</tt>) is as follows. In each
3690 case, if a major error occurs (unless listed below) the
3691 actions are, in general, run backwards - this means that the
3692 maintainer scripts are run with different arguments in
3693 reverse order. These are the "error unwind" calls listed
3700 If a version of the package is already installed, call
3701 <example compact="compact">
3702 <var>old-prerm</var> upgrade <var>new-version</var>
3706 If the script runs but exits with a non-zero
3707 exit status, <prgn>dpkg</prgn> will attempt:
3708 <example compact="compact">
3709 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3711 If this works, the upgrade continues. If this
3712 does not work, the error unwind:
3713 <example compact="compact">
3714 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3716 If this works, then the old-version is
3717 "Installed", if not, the old version is in a
3718 "Failed-Config" state.
3724 If a "conflicting" package is being removed at the same time,
3725 or if any package will be broken (due to <tt>Breaks</tt>):
3728 If <tt>--auto-deconfigure</tt> is
3729 specified, call, for each package to be deconfigured
3730 due to <tt>Breaks</tt>:
3731 <example compact="compact">
3732 <var>deconfigured's-prerm</var> deconfigure \
3733 in-favour <var>package-being-installed</var> <var>version</var>
3736 <example compact="compact">
3737 <var>deconfigured's-postinst</var> abort-deconfigure \
3738 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3740 The deconfigured packages are marked as
3741 requiring configuration, so that if
3742 <tt>--install</tt> is used they will be
3743 configured again if possible.
3746 If any packages depended on a conflicting
3747 package being removed and <tt>--auto-deconfigure</tt> is
3748 specified, call, for each such package:
3749 <example compact="compact">
3750 <var>deconfigured's-prerm</var> deconfigure \
3751 in-favour <var>package-being-installed</var> <var>version</var> \
3752 removing <var>conflicting-package</var> <var>version</var>
3755 <example compact="compact">
3756 <var>deconfigured's-postinst</var> abort-deconfigure \
3757 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3758 removing <var>conflicting-package</var> <var>version</var>
3760 The deconfigured packages are marked as
3761 requiring configuration, so that if
3762 <tt>--install</tt> is used they will be
3763 configured again if possible.
3766 To prepare for removal of each conflicting package, call:
3767 <example compact="compact">
3768 <var>conflictor's-prerm</var> remove \
3769 in-favour <var>package</var> <var>new-version</var>
3772 <example compact="compact">
3773 <var>conflictor's-postinst</var> abort-remove \
3774 in-favour <var>package</var> <var>new-version</var>
3783 If the package is being upgraded, call:
3784 <example compact="compact">
3785 <var>new-preinst</var> upgrade <var>old-version</var>
3787 If this fails, we call:
3789 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3796 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3798 is called. If this works, then the old version
3799 is in an "Installed" state, or else it is left
3800 in an "Unpacked" state.
3805 If it fails, then the old version is left
3806 in an "Half-Installed" state.
3813 Otherwise, if the package had some configuration
3814 files from a previous version installed (i.e., it
3815 is in the "configuration files only" state):
3816 <example compact="compact">
3817 <var>new-preinst</var> install <var>old-version</var>
3821 <var>new-postrm</var> abort-install <var>old-version</var>
3823 If this fails, the package is left in a
3824 "Half-Installed" state, which requires a
3825 reinstall. If it works, the packages is left in
3826 a "Config Files" state.
3829 Otherwise (i.e., the package was completely purged):
3830 <example compact="compact">
3831 <var>new-preinst</var> install
3834 <example compact="compact">
3835 <var>new-postrm</var> abort-install
3837 If the error-unwind fails, the package is in a
3838 "Half Installed" phase, and requires a
3839 reinstall. If the error unwind works, the
3840 package is in a not installed state.
3847 The new package's files are unpacked, overwriting any
3848 that may be on the system already, for example any
3849 from the old version of the same package or from
3850 another package. Backups of the old files are kept
3851 temporarily, and if anything goes wrong the package
3852 management system will attempt to put them back as
3853 part of the error unwind.
3857 It is an error for a package to contain files which
3858 are on the system in another package, unless
3859 <tt>Replaces</tt> is used (see <ref id="replaces">).
3861 The following paragraph is not currently the case:
3862 Currently the <tt>- - force-overwrite</tt> flag is
3863 enabled, downgrading it to a warning, but this may not
3869 It is a more serious error for a package to contain a
3870 plain file or other kind of non-directory where another
3871 package has a directory (again, unless
3872 <tt>Replaces</tt> is used). This error can be
3873 overridden if desired using
3874 <tt>--force-overwrite-dir</tt>, but this is not
3879 Packages which overwrite each other's files produce
3880 behavior which, though deterministic, is hard for the
3881 system administrator to understand. It can easily
3882 lead to "missing" programs if, for example, a package
3883 is installed which overwrites a file from another
3884 package, and is then removed again.<footnote>
3885 Part of the problem is due to what is arguably a
3886 bug in <prgn>dpkg</prgn>.
3891 A directory will never be replaced by a symbolic link
3892 to a directory or vice versa; instead, the existing
3893 state (symlink or not) will be left alone and
3894 <prgn>dpkg</prgn> will follow the symlink if there is
3903 If the package is being upgraded, call
3904 <example compact="compact">
3905 <var>old-postrm</var> upgrade <var>new-version</var>
3909 If this fails, <prgn>dpkg</prgn> will attempt:
3910 <example compact="compact">
3911 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3913 If this works, installation continues. If not,
3915 <example compact="compact">
3916 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3918 If this fails, the old version is left in an
3919 "Half Installed" state. If it works, dpkg now
3921 <example compact="compact">
3922 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3924 If this fails, the old version is left in an
3925 "Half Installed" state. If it works, dpkg now
3927 <example compact="compact">
3928 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3930 If this fails, the old version is in an
3937 This is the point of no return - if
3938 <prgn>dpkg</prgn> gets this far, it won't back off
3939 past this point if an error occurs. This will
3940 leave the package in a fairly bad state, which
3941 will require a successful re-installation to clear
3942 up, but it's when <prgn>dpkg</prgn> starts doing
3943 things that are irreversible.
3948 Any files which were in the old version of the package
3949 but not in the new are removed.
3953 The new file list replaces the old.
3957 The new maintainer scripts replace the old.
3961 Any packages all of whose files have been overwritten
3962 during the installation, and which aren't required for
3963 dependencies, are considered to have been removed.
3964 For each such package
3967 <prgn>dpkg</prgn> calls:
3968 <example compact="compact">
3969 <var>disappearer's-postrm</var> disappear \
3970 <var>overwriter</var> <var>overwriter-version</var>
3974 The package's maintainer scripts are removed.
3977 It is noted in the status database as being in a
3978 sane state, namely not installed (any conffiles
3979 it may have are ignored, rather than being
3980 removed by <prgn>dpkg</prgn>). Note that
3981 disappearing packages do not have their prerm
3982 called, because <prgn>dpkg</prgn> doesn't know
3983 in advance that the package is going to
3990 Any files in the package we're unpacking that are also
3991 listed in the file lists of other packages are removed
3992 from those lists. (This will lobotomize the file list
3993 of the "conflicting" package if there is one.)
3997 The backup files made during installation, above, are
4003 The new package's status is now sane, and recorded as
4008 Here is another point of no return - if the
4009 conflicting package's removal fails we do not unwind
4010 the rest of the installation; the conflicting package
4011 is left in a half-removed limbo.
4016 If there was a conflicting package we go and do the
4017 removal actions (described below), starting with the
4018 removal of the conflicting package's files (any that
4019 are also in the package being installed have already
4020 been removed from the conflicting package's file list,
4021 and so do not get removed now).
4027 <sect id="configdetails"><heading>Details of configuration</heading>
4030 When we configure a package (this happens with <tt>dpkg
4031 --install</tt> and <tt>dpkg --configure</tt>), we first
4032 update any <tt>conffile</tt>s and then call:
4033 <example compact="compact">
4034 <var>postinst</var> configure <var>most-recently-configured-version</var>
4039 No attempt is made to unwind after errors during
4040 configuration. If the configuration fails, the package is in
4041 a "Failed Config" state, and an error message is generated.
4045 If there is no most recently configured version
4046 <prgn>dpkg</prgn> will pass a null argument.
4049 Historical note: Truly ancient (pre-1997) versions of
4050 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4051 (including the angle brackets) in this case. Even older
4052 ones did not pass a second argument at all, under any
4053 circumstance. Note that upgrades using such an old dpkg
4054 version are unlikely to work for other reasons, even if
4055 this old argument behavior is handled by your postinst script.
4061 <sect id="removedetails"><heading>Details of removal and/or
4062 configuration purging</heading>
4068 <example compact="compact">
4069 <var>prerm</var> remove
4073 If prerm fails during replacement due to conflict
4075 <var>conflictor's-postinst</var> abort-remove \
4076 in-favour <var>package</var> <var>new-version</var>
4080 <var>postinst</var> abort-remove
4084 If this fails, the package is in a "Failed-Config"
4085 state, or else it remains "Installed".
4089 The package's files are removed (except <tt>conffile</tt>s).
4092 <example compact="compact">
4093 <var>postrm</var> remove
4097 If it fails, there's no error unwind, and the package is in
4098 an "Half-Installed" state.
4103 All the maintainer scripts except the <prgn>postrm</prgn>
4108 If we aren't purging the package we stop here. Note
4109 that packages which have no <prgn>postrm</prgn> and no
4110 <tt>conffile</tt>s are automatically purged when
4111 removed, as there is no difference except for the
4112 <prgn>dpkg</prgn> status.
4116 The <tt>conffile</tt>s and any backup files
4117 (<tt>~</tt>-files, <tt>#*#</tt> files,
4118 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4123 <example compact="compact">
4124 <var>postrm</var> purge
4128 If this fails, the package remains in a "Config-Files"
4133 The package's file list is removed.
4142 <chapt id="relationships">
4143 <heading>Declaring relationships between packages</heading>
4145 <sect id="depsyntax">
4146 <heading>Syntax of relationship fields</heading>
4149 These fields all have a uniform syntax. They are a list of
4150 package names separated by commas.
4154 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4155 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4156 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4157 control file fields of the package, which declare
4158 dependencies on other packages, the package names listed may
4159 also include lists of alternative package names, separated
4160 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4161 if any one of the alternative packages is installed, that
4162 part of the dependency is considered to be satisfied.
4166 All of the fields except for <tt>Provides</tt> may restrict
4167 their applicability to particular versions of each named
4168 package. This is done in parentheses after each individual
4169 package name; the parentheses should contain a relation from
4170 the list below followed by a version number, in the format
4171 described in <ref id="f-Version">.
4175 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4176 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4177 strictly earlier, earlier or equal, exactly equal, later or
4178 equal and strictly later, respectively. The deprecated
4179 forms <tt><</tt> and <tt>></tt> were used to mean
4180 earlier/later or equal, rather than strictly earlier/later,
4181 so they should not appear in new packages (though
4182 <prgn>dpkg</prgn> still supports them).
4186 Whitespace may appear at any point in the version
4187 specification subject to the rules in <ref
4188 id="controlsyntax">, and must appear where it's necessary to
4189 disambiguate; it is not otherwise significant. All of the
4190 relationship fields may span multiple lines. For
4191 consistency and in case of future changes to
4192 <prgn>dpkg</prgn> it is recommended that a single space be
4193 used after a version relationship and before a version
4194 number; it is also conventional to put a single space after
4195 each comma, on either side of each vertical bar, and before
4196 each open parenthesis. When wrapping a relationship field, it
4197 is conventional to do so after a comma and before the space
4198 following that comma.
4202 For example, a list of dependencies might appear as:
4203 <example compact="compact">
4206 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4211 All fields that specify build-time relationships
4212 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4213 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4214 may be restricted to a certain set of architectures. This
4215 is indicated in brackets after each individual package name and
4216 the optional version specification. The brackets enclose a
4217 list of Debian architecture names separated by whitespace.
4218 Exclamation marks may be prepended to each of the names.
4219 (It is not permitted for some names to be prepended with
4220 exclamation marks while others aren't.) If the current Debian
4221 host architecture is not in this list and there are no
4222 exclamation marks in the list, or it is in the list with a
4223 prepended exclamation mark, the package name and the
4224 associated version specification are ignored completely for
4225 the purposes of defining the relationships.
4230 <example compact="compact">
4232 Build-Depends-Indep: texinfo
4233 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4234 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4236 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4237 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4238 <tt>gnumach-dev</tt> only on hurd-i386.
4242 If the architecture-restricted dependency is part of a set of
4243 alternatives using <tt>|</tt>, that alternative is ignored
4244 completely on architectures that do not match the restriction.
4246 <example compact="compact">
4247 Build-Depends: foo [!i386] | bar [!amd64]
4249 is equivalent to <tt>bar</tt> on the i386 architecture, to
4250 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4251 bar</tt> on all other architectures.
4255 Note that the binary package relationship fields such as
4256 <tt>Depends</tt> appear in one of the binary package
4257 sections of the control file, whereas the build-time
4258 relationships such as <tt>Build-Depends</tt> appear in the
4259 source package section of the control file (which is the
4264 <sect id="binarydeps">
4265 <heading>Binary Dependencies - <tt>Depends</tt>,
4266 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4267 <tt>Pre-Depends</tt>
4271 Packages can declare in their control file that they have
4272 certain relationships to other packages - for example, that
4273 they may not be installed at the same time as certain other
4274 packages, and/or that they depend on the presence of others.
4278 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4279 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4280 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4281 <tt>Breaks</tt> is described in <ref id="breaks">, and
4282 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4283 rest are described below.
4287 These seven fields are used to declare a dependency
4288 relationship by one package on another. Except for
4289 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4290 depending (binary) package's control file.
4291 (<tt>Enhances</tt> appears in the recommending package's
4292 control file, and <tt>Breaks</tt> appears in the version of
4293 depended-on package which causes the named package to
4298 A <tt>Depends</tt> field takes effect <em>only</em> when a
4299 package is to be configured. It does not prevent a package
4300 being on the system in an unconfigured state while its
4301 dependencies are unsatisfied, and it is possible to replace
4302 a package whose dependencies are satisfied and which is
4303 properly installed with a different version whose
4304 dependencies are not and cannot be satisfied; when this is
4305 done the depending package will be left unconfigured (since
4306 attempts to configure it will give errors) and will not
4307 function properly. If it is necessary, a
4308 <tt>Pre-Depends</tt> field can be used, which has a partial
4309 effect even when a package is being unpacked, as explained
4310 in detail below. (The other three dependency fields,
4311 <tt>Recommends</tt>, <tt>Suggests</tt> and
4312 <tt>Enhances</tt>, are only used by the various front-ends
4313 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4314 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4318 For this reason packages in an installation run are usually
4319 all unpacked first and all configured later; this gives
4320 later versions of packages with dependencies on later
4321 versions of other packages the opportunity to have their
4322 dependencies satisfied.
4326 In case of circular dependencies, since installation or
4327 removal order honoring the dependency order can't be
4328 established, dependency loops are broken at some point
4329 (based on rules below), and some packages may not be able to
4330 rely on their dependencies being present when being
4331 installed or removed, depending on which side of the break
4332 of the circular dependency loop they happen to be on. If one
4333 of the packages in the loop has no postinst script, then the
4334 cycle will be broken at that package, so as to ensure that
4335 all postinst scripts run with the dependencies properly
4336 configured if this is possible. Otherwise the breaking point
4341 The <tt>Depends</tt> field thus allows package maintainers
4342 to impose an order in which packages should be configured.
4346 The meaning of the five dependency fields is as follows:
4348 <tag><tt>Depends</tt></tag>
4351 This declares an absolute dependency. A package will
4352 not be configured unless all of the packages listed in
4353 its <tt>Depends</tt> field have been correctly
4358 The <tt>Depends</tt> field should be used if the
4359 depended-on package is required for the depending
4360 package to provide a significant amount of
4365 The <tt>Depends</tt> field should also be used if the
4366 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4367 <prgn>postrm</prgn> scripts require the package to be
4368 present in order to run. Note, however, that the
4369 <prgn>postrm</prgn> cannot rely on any non-essential
4370 packages to be present during the <tt>purge</tt>
4374 <tag><tt>Recommends</tt></tag>
4377 This declares a strong, but not absolute, dependency.
4381 The <tt>Recommends</tt> field should list packages
4382 that would be found together with this one in all but
4383 unusual installations.
4387 <tag><tt>Suggests</tt></tag>
4389 This is used to declare that one package may be more
4390 useful with one or more others. Using this field
4391 tells the packaging system and the user that the
4392 listed packages are related to this one and can
4393 perhaps enhance its usefulness, but that installing
4394 this one without them is perfectly reasonable.
4397 <tag><tt>Enhances</tt></tag>
4399 This field is similar to Suggests but works in the
4400 opposite direction. It is used to declare that a
4401 package can enhance the functionality of another
4405 <tag><tt>Pre-Depends</tt></tag>
4408 This field is like <tt>Depends</tt>, except that it
4409 also forces <prgn>dpkg</prgn> to complete installation
4410 of the packages named before even starting the
4411 installation of the package which declares the
4412 pre-dependency, as follows:
4416 When a package declaring a pre-dependency is about to
4417 be <em>unpacked</em> the pre-dependency can be
4418 satisfied if the depended-on package is either fully
4419 configured, <em>or even if</em> the depended-on
4420 package(s) are only unpacked or half-configured,
4421 provided that they have been configured correctly at
4422 some point in the past (and not removed or partially
4423 removed since). In this case, both the
4424 previously-configured and currently unpacked or
4425 half-configured versions must satisfy any version
4426 clause in the <tt>Pre-Depends</tt> field.
4430 When the package declaring a pre-dependency is about
4431 to be <em>configured</em>, the pre-dependency will be
4432 treated as a normal <tt>Depends</tt>, that is, it will
4433 be considered satisfied only if the depended-on
4434 package has been correctly configured.
4438 <tt>Pre-Depends</tt> should be used sparingly,
4439 preferably only by packages whose premature upgrade or
4440 installation would hamper the ability of the system to
4441 continue with any upgrade that might be in progress.
4445 <tt>Pre-Depends</tt> are also required if the
4446 <prgn>preinst</prgn> script depends on the named
4447 package. It is best to avoid this situation if
4455 When selecting which level of dependency to use you should
4456 consider how important the depended-on package is to the
4457 functionality of the one declaring the dependency. Some
4458 packages are composed of components of varying degrees of
4459 importance. Such a package should list using
4460 <tt>Depends</tt> the package(s) which are required by the
4461 more important components. The other components'
4462 requirements may be mentioned as Suggestions or
4463 Recommendations, as appropriate to the components' relative
4469 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4472 When one binary package declares that it breaks another,
4473 <prgn>dpkg</prgn> will refuse to allow the package which
4474 declares <tt>Breaks</tt> be installed unless the broken
4475 package is deconfigured first, and it will refuse to
4476 allow the broken package to be reconfigured.
4480 A package will not be regarded as causing breakage merely
4481 because its configuration files are still installed; it must
4482 be at least half-installed.
4486 A special exception is made for packages which declare that
4487 they break their own package name or a virtual package which
4488 they provide (see below): this does not count as a real
4493 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4494 version clause; such a <tt>Breaks</tt> is introduced in the
4495 version of an (implicit or explicit) dependency which
4496 violates an assumption or reveals a bug in earlier versions
4497 of the broken package. This use of <tt>Breaks</tt> will
4498 inform higher-level package management tools that broken
4499 package must be upgraded before the new one.
4503 If the breaking package also overwrites some files from the
4504 older package, it should use <tt>Replaces</tt> (not
4505 <tt>Conflicts</tt>) to ensure this goes smoothly.
4509 <sect id="conflicts">
4510 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4513 When one binary package declares a conflict with another
4514 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4515 refuse to allow them to be installed on the system at the
4520 If one package is to be installed, the other must be removed
4521 first - if the package being installed is marked as
4522 replacing (see <ref id="replaces">) the one on the system,
4523 or the one on the system is marked as deselected, or both
4524 packages are marked <tt>Essential</tt>, then
4525 <prgn>dpkg</prgn> will automatically remove the package
4526 which is causing the conflict, otherwise it will halt the
4527 installation of the new package with an error. This
4528 mechanism is specifically designed to produce an error when
4529 the installed package is <tt>Essential</tt>, but the new
4534 A package will not cause a conflict merely because its
4535 configuration files are still installed; it must be at least
4540 A special exception is made for packages which declare a
4541 conflict with their own package name, or with a virtual
4542 package which they provide (see below): this does not
4543 prevent their installation, and allows a package to conflict
4544 with others providing a replacement for it. You use this
4545 feature when you want the package in question to be the only
4546 package providing some feature.
4550 A <tt>Conflicts</tt> entry should almost never have an
4551 "earlier than" version clause. This would prevent
4552 <prgn>dpkg</prgn> from upgrading or installing the package
4553 which declared such a conflict until the upgrade or removal
4554 of the conflicted-with package had been completed. Instead,
4555 <tt>Breaks</tt> may be used.
4559 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4563 As well as the names of actual ("concrete") packages, the
4564 package relationship fields <tt>Depends</tt>,
4565 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4566 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4567 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4568 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4569 may mention "virtual packages".
4573 A <em>virtual package</em> is one which appears in the
4574 <tt>Provides</tt> control file field of another package.
4575 The effect is as if the package(s) which provide a
4576 particular virtual package name had been listed by name
4577 everywhere the virtual package name appears. (See also <ref
4582 If there are both concrete and virtual packages of the same
4583 name, then the dependency may be satisfied (or the conflict
4584 caused) by either the concrete package with the name in
4585 question or any other concrete package which provides the
4586 virtual package with the name in question. This is so that,
4587 for example, supposing we have
4588 <example compact="compact">
4591 </example> and someone else releases an enhanced version of
4592 the <tt>bar</tt> package they can say:
4593 <example compact="compact">
4597 and the <tt>bar-plus</tt> package will now also satisfy the
4598 dependency for the <tt>foo</tt> package.
4602 If a relationship field has a version number attached
4603 then only real packages will be considered to see whether
4604 the relationship is satisfied (or the prohibition violated,
4605 for a conflict or breakage) - it is assumed that a real
4606 package which provides the virtual package is not of the
4607 "right" version. So, a <tt>Provides</tt> field may not
4608 contain version numbers, and the version number of the
4609 concrete package which provides a particular virtual package
4610 will not be looked at when considering a dependency on or
4611 conflict with the virtual package name.
4615 It is likely that the ability will be added in a future
4616 release of <prgn>dpkg</prgn> to specify a version number for
4617 each virtual package it provides. This feature is not yet
4618 present, however, and is expected to be used only
4623 If you want to specify which of a set of real packages
4624 should be the default to satisfy a particular dependency on
4625 a virtual package, you should list the real package as an
4626 alternative before the virtual one.
4631 <sect id="replaces"><heading>Overwriting files and replacing
4632 packages - <tt>Replaces</tt></heading>
4635 Packages can declare in their control file that they should
4636 overwrite files in certain other packages, or completely
4637 replace other packages. The <tt>Replaces</tt> control file
4638 field has these two distinct purposes.
4641 <sect1><heading>Overwriting files in other packages</heading>
4644 Firstly, as mentioned before, it is usually an error for a
4645 package to contain files which are on the system in
4650 However, if the overwriting package declares that it
4651 <tt>Replaces</tt> the one containing the file being
4652 overwritten, then <prgn>dpkg</prgn> will replace the file
4653 from the old package with that from the new. The file
4654 will no longer be listed as "owned" by the old package.
4658 If a package is completely replaced in this way, so that
4659 <prgn>dpkg</prgn> does not know of any files it still
4660 contains, it is considered to have "disappeared". It will
4661 be marked as not wanted on the system (selected for
4662 removal) and not installed. Any <tt>conffile</tt>s
4663 details noted for the package will be ignored, as they
4664 will have been taken over by the overwriting package. The
4665 package's <prgn>postrm</prgn> script will be run with a
4666 special argument to allow the package to do any final
4667 cleanup required. See <ref id="mscriptsinstact">.
4670 Replaces is a one way relationship -- you have to
4671 install the replacing package after the replaced
4678 For this usage of <tt>Replaces</tt>, virtual packages (see
4679 <ref id="virtual">) are not considered when looking at a
4680 <tt>Replaces</tt> field - the packages declared as being
4681 replaced must be mentioned by their real names.
4685 Furthermore, this usage of <tt>Replaces</tt> only takes
4686 effect when both packages are at least partially on the
4687 system at once, so that it can only happen if they do not
4688 conflict or if the conflict has been overridden.
4693 <sect1><heading>Replacing whole packages, forcing their
4697 Secondly, <tt>Replaces</tt> allows the packaging system to
4698 resolve which package should be removed when there is a
4699 conflict - see <ref id="conflicts">. This usage only
4700 takes effect when the two packages <em>do</em> conflict,
4701 so that the two usages of this field do not interfere with
4706 In this situation, the package declared as being replaced
4707 can be a virtual package, so for example, all mail
4708 transport agents (MTAs) would have the following fields in
4709 their control files:
4710 <example compact="compact">
4711 Provides: mail-transport-agent
4712 Conflicts: mail-transport-agent
4713 Replaces: mail-transport-agent
4715 ensuring that only one MTA can be installed at any one
4720 <sect id="sourcebinarydeps">
4721 <heading>Relationships between source and binary packages -
4722 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4723 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4727 Source packages that require certain binary packages to be
4728 installed or absent at the time of building the package
4729 can declare relationships to those binary packages.
4733 This is done using the <tt>Build-Depends</tt>,
4734 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4735 <tt>Build-Conflicts-Indep</tt> control file fields.
4739 Build-dependencies on "build-essential" binary packages can be
4740 omitted. Please see <ref id="pkg-relations"> for more information.
4744 The dependencies and conflicts they define must be satisfied
4745 (as defined earlier for binary packages) in order to invoke
4746 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4748 If you make "build-arch" or "binary-arch", you need
4749 Build-Depends. If you make "build-indep" or
4750 "binary-indep", you need Build-Depends and
4751 Build-Depends-Indep. If you make "build" or "binary",
4755 There is no Build-Depends-Arch; this role is essentially
4756 met with Build-Depends. Anyone building the
4757 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4758 is basically assumed to be building the whole package
4759 anyway and so installs all build dependencies. The
4760 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4761 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4762 does not yet know how to check for its existence) and
4763 <tt>binary-arch</tt>.
4766 The purpose of the original split, I recall, was so that
4767 the autobuilders wouldn't need to install extra packages
4768 needed only for the binary-indep targets. But without a
4769 build-arch/build-indep split, this didn't work, since
4770 most of the work is done in the build target, not in the
4776 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4778 The <tt>Build-Depends</tt> and
4779 <tt>Build-Conflicts</tt> fields must be satisfied when
4780 any of the following targets is invoked:
4781 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4782 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4783 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4785 <tag><tt>Build-Depends-Indep</tt>,
4786 <tt>Build-Conflicts-Indep</tt></tag>
4788 The <tt>Build-Depends-Indep</tt> and
4789 <tt>Build-Conflicts-Indep</tt> fields must be
4790 satisfied when any of the following targets is
4791 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4792 <tt>binary</tt> and <tt>binary-indep</tt>.
4802 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4805 Packages containing shared libraries must be constructed with
4806 a little care to make sure that the shared library is always
4807 available. This is especially important for packages whose
4808 shared libraries are vitally important, such as the C library
4809 (currently <tt>libc6</tt>).
4813 Packages involving shared libraries should be split up into
4814 several binary packages. This section mostly deals with how
4815 this separation is to be accomplished; rules for files within
4816 the shared library packages are in <ref id="libraries"> instead.
4819 <sect id="sharedlibs-runtime">
4820 <heading>Run-time shared libraries</heading>
4823 The run-time shared library needs to be placed in a package
4824 whose name changes whenever the shared object version
4827 Since it is common place to install several versions of a
4828 package that just provides shared libraries, it is a
4829 good idea that the library package should not
4830 contain any extraneous non-versioned files, unless they
4831 happen to be in versioned directories.</p>
4833 The most common mechanism is to place it in a package
4835 <package><var>libraryname</var><var>soversion</var></package>,
4836 where <file><var>soversion</var></file> is the version number
4837 in the soname of the shared library<footnote>
4838 The soname is the shared object name: it's the thing
4839 that has to match exactly between building an executable
4840 and running it for the dynamic linker to be able run the
4841 program. For example, if the soname of the library is
4842 <file>libfoo.so.6</file>, the library package would be
4843 called <file>libfoo6</file>.
4845 Alternatively, if it would be confusing to directly append
4846 <var>soversion</var> to <var>libraryname</var> (e.g. because
4847 <var>libraryname</var> itself ends in a number), you may use
4848 <package><var>libraryname</var>-<var>soversion</var></package> and
4849 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4854 If you have several shared libraries built from the same
4855 source tree you may lump them all together into a single
4856 shared library package, provided that you change all of
4857 their sonames at once (so that you don't get filename
4858 clashes if you try to install different versions of the
4859 combined shared libraries package).
4863 The package should install the shared libraries under
4864 their normal names. For example, the <package>libgdbm3</package>
4865 package should install <file>libgdbm.so.3.0.0</file> as
4866 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4867 renamed or re-linked by any <prgn>prerm</prgn> or
4868 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4869 of renaming things safely without affecting running programs,
4870 and attempts to interfere with this are likely to lead to
4875 Shared libraries should not be installed executable, since
4876 the dynamic linker does not require this and trying to
4877 execute a shared library usually results in a core dump.
4881 The run-time library package should include the symbolic link that
4882 <prgn>ldconfig</prgn> would create for the shared libraries.
4883 For example, the <package>libgdbm3</package> package should include
4884 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4885 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4886 linker (for example <prgn>ld.so</prgn> or
4887 <prgn>ld-linux.so.*</prgn>) can find the library between the
4888 time that <prgn>dpkg</prgn> installs it and the time that
4889 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4891 The package management system requires the library to be
4892 placed before the symbolic link pointing to it in the
4893 <file>.deb</file> file. This is so that when
4894 <prgn>dpkg</prgn> comes to install the symlink
4895 (overwriting the previous symlink pointing at an older
4896 version of the library), the new shared library is already
4897 in place. In the past, this was achieved by creating the
4898 library in the temporary packaging directory before
4899 creating the symlink. Unfortunately, this was not always
4900 effective, since the building of the tar file in the
4901 <file>.deb</file> depended on the behavior of the underlying
4902 file system. Some file systems (such as reiserfs) reorder
4903 the files so that the order of creation is forgotten.
4904 Since version 1.7.0, <prgn>dpkg</prgn>
4905 reorders the files itself as necessary when building a
4906 package. Thus it is no longer important to concern
4907 oneself with the order of file creation.
4911 <sect1 id="ldconfig">
4912 <heading><tt>ldconfig</tt></heading>
4915 Any package installing shared libraries in one of the default
4916 library directories of the dynamic linker (which are currently
4917 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4918 listed in <file>/etc/ld.so.conf</file><footnote>
4920 <list compact="compact">
4921 <item>/usr/local/lib</item>
4922 <item>/usr/lib/libc5-compat</item>
4923 <item>/lib/libc5-compat</item>
4926 must use <prgn>ldconfig</prgn> to update the shared library
4931 The package maintainer scripts must only call
4932 <prgn>ldconfig</prgn> under these circumstances:
4933 <list compact="compact">
4934 <item>When the <prgn>postinst</prgn> script is run with a
4935 first argument of <tt>configure</tt>, the script must call
4936 <prgn>ldconfig</prgn>, and may optionally invoke
4937 <prgn>ldconfig</prgn> at other times.
4939 <item>When the <prgn>postrm</prgn> script is run with a
4940 first argument of <tt>remove</tt>, the script should call
4941 <prgn>ldconfig</prgn>.
4946 During install or upgrade, the preinst is called before
4947 the new files are installed, so calling "ldconfig" is
4948 pointless. The preinst of an existing package can also be
4949 called if an upgrade fails. However, this happens during
4950 the critical time when a shared libs may exist on-disk
4951 under a temporary name. Thus, it is dangerous and
4952 forbidden by current policy to call "ldconfig" at this
4957 When a package is installed or upgraded, "postinst
4958 configure" runs after the new files are safely on-disk.
4959 Since it is perfectly safe to invoke ldconfig
4960 unconditionally in a postinst, it is OK for a package to
4961 simply put ldconfig in its postinst without checking the
4962 argument. The postinst can also be called to recover from
4963 a failed upgrade. This happens before any new files are
4964 unpacked, so there is no reason to call "ldconfig" at this
4969 For a package that is being removed, prerm is
4970 called with all the files intact, so calling ldconfig is
4971 useless. The other calls to "prerm" happen in the case of
4972 upgrade at a time when all the files of the old package
4973 are on-disk, so again calling "ldconfig" is pointless.
4977 postrm, on the other hand, is called with the "remove"
4978 argument just after the files are removed, so this is
4979 the proper time to call "ldconfig" to notify the system
4980 of the fact that the shared libraries from the package
4981 are removed. The postrm can be called at several other
4982 times. At the time of "postrm purge", "postrm
4983 abort-install", or "postrm abort-upgrade", calling
4984 "ldconfig" is useless because the shared lib files are
4985 not on-disk. However, when "postrm" is invoked with
4986 arguments "upgrade", "failed-upgrade", or "disappear", a
4987 shared lib may exist on-disk under a temporary filename.
4995 <sect id="sharedlibs-support-files">
4996 <heading>Shared library support files</heading>
4999 If your package contains files whose names do not change with
5000 each change in the library shared object version, you must not
5001 put them in the shared library package. Otherwise, several
5002 versions of the shared library cannot be installed at the same
5003 time without filename clashes, making upgrades and transitions
5004 unnecessarily difficult.
5008 It is recommended that supporting files and run-time support
5009 programs that do not need to be invoked manually by users, but
5010 are nevertheless required for the package to function, be placed
5011 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5012 preferably under <file>/usr/lib/</file><var>package-name</var>.
5013 If the program or file is architecture independent, the
5014 recommendation is for it to be placed in a subdirectory of
5015 <file>/usr/share</file> instead, preferably under
5016 <file>/usr/share/</file><var>package-name</var>. Following the
5017 <var>package-name</var> naming convention ensures that the file
5018 names change when the shared object version changes.
5022 Run-time support programs that use the shared library but are
5023 not required for the library to function or files used by the
5024 shared library that can be used by any version of the shared
5025 library package should instead be put in a separate package.
5026 This package might typically be named
5027 <package><var>libraryname</var>-tools</package>; note the
5028 absence of the <var>soversion</var> in the package name.
5032 Files and support programs only useful when compiling software
5033 against the library should be included in the development
5034 package for the library.<footnote>
5035 For example, a <file><var>package-name</var>-config</file>
5036 script or <package>pkg-config</package> configuration files.
5041 <sect id="sharedlibs-static">
5042 <heading>Static libraries</heading>
5045 The static library (<file><var>libraryname.a</var></file>)
5046 is usually provided in addition to the shared version.
5047 It is placed into the development package (see below).
5051 In some cases, it is acceptable for a library to be
5052 available in static form only; these cases include:
5054 <item>libraries for languages whose shared library support
5055 is immature or unstable</item>
5056 <item>libraries whose interfaces are in flux or under
5057 development (commonly the case when the library's
5058 major version number is zero, or where the ABI breaks
5059 across patchlevels)</item>
5060 <item>libraries which are explicitly intended to be
5061 available only in static form by their upstream
5066 <sect id="sharedlibs-dev">
5067 <heading>Development files</heading>
5070 The development files associated to a shared library need to be
5071 placed in a package called
5072 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5073 or if you prefer only to support one development version at a
5074 time, <package><var>libraryname</var>-dev</package>.
5078 In case several development versions of a library exist, you may
5079 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5080 <ref id="conflicts">) to ensure that the user only installs one
5081 development version at a time (as different development versions are
5082 likely to have the same header files in them, which would cause a
5083 filename clash if both were installed).
5087 The development package should contain a symlink for the associated
5088 shared library without a version number. For example, the
5089 <package>libgdbm-dev</package> package should include a symlink
5090 from <file>/usr/lib/libgdbm.so</file> to
5091 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5092 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5093 <file>libgdbm.so</file> when compiling dynamically.
5097 <sect id="sharedlibs-intradeps">
5098 <heading>Dependencies between the packages of the same library</heading>
5101 Typically the development version should have an exact
5102 version dependency on the runtime library, to make sure that
5103 compilation and linking happens correctly. The
5104 <tt>${binary:Version}</tt> substitution variable can be
5105 useful for this purpose.
5107 Previously, <tt>${Source-Version}</tt> was used, but its name
5108 was confusing and it has been deprecated since dpkg 1.13.19.
5113 <sect id="sharedlibs-shlibdeps">
5114 <heading>Dependencies between the library and other packages -
5115 the <tt>shlibs</tt> system</heading>
5118 If a package contains a binary or library which links to a
5119 shared library, we must ensure that when the package is
5120 installed on the system, all of the libraries needed are
5121 also installed. This requirement led to the creation of the
5122 <tt>shlibs</tt> system, which is very simple in its design:
5123 any package which <em>provides</em> a shared library also
5124 provides information on the package dependencies required to
5125 ensure the presence of this library, and any package which
5126 <em>uses</em> a shared library uses this information to
5127 determine the dependencies it requires. The files which
5128 contain the mapping from shared libraries to the necessary
5129 dependency information are called <file>shlibs</file> files.
5133 Thus, when a package is built which contains any shared
5134 libraries, it must provide a <file>shlibs</file> file for other
5135 packages to use, and when a package is built which contains
5136 any shared libraries or compiled binaries, it must run
5137 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5138 on these to determine the libraries used and hence the
5139 dependencies needed by this package.<footnote>
5141 In the past, the shared libraries linked to were
5142 determined by calling <prgn>ldd</prgn>, but now
5143 <prgn>objdump</prgn> is used to do this. The only
5144 change this makes to package building is that
5145 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5146 libraries, whereas in the past this was unnecessary.
5147 The rest of this footnote explains the advantage that
5152 We say that a binary <tt>foo</tt> <em>directly</em> uses
5153 a library <tt>libbar</tt> if it is explicitly linked
5154 with that library (that is, it uses the flag
5155 <tt>-lbar</tt> during the linking stage). Other
5156 libraries that are needed by <tt>libbar</tt> are linked
5157 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5158 linker will load them automatically when it loads
5159 <tt>libbar</tt>. A package should depend on
5160 the libraries it directly uses, and the dependencies for
5161 those libraries should automatically pull in the other
5166 Unfortunately, the <prgn>ldd</prgn> program shows both
5167 the directly and indirectly used libraries, meaning that
5168 the dependencies determined included both direct and
5169 indirect dependencies. The use of <prgn>objdump</prgn>
5170 avoids this problem by determining only the directly
5175 A good example of where this helps is the following. We
5176 could update <tt>libimlib</tt> with a new version that
5177 supports a new graphics format called dgf (but retaining
5178 the same major version number). If we used the old
5179 <prgn>ldd</prgn> method, every package that uses
5180 <tt>libimlib</tt> would need to be recompiled so it
5181 would also depend on <tt>libdgf</tt> or it wouldn't run
5182 due to missing symbols. However with the new system,
5183 packages using <tt>libimlib</tt> can rely on
5184 <tt>libimlib</tt> itself having the dependency on
5185 <tt>libdgf</tt> and so they would not need rebuilding.
5191 In the following sections, we will first describe where the
5192 various <tt>shlibs</tt> files are to be found, then how to
5193 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5194 file format and how to create them if your package contains a
5199 <heading>The <tt>shlibs</tt> files present on the system</heading>
5202 There are several places where <tt>shlibs</tt> files are
5203 found. The following list gives them in the order in which
5205 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5206 (The first one which gives the required information is used.)
5212 <p><file>debian/shlibs.local</file></p>
5215 This lists overrides for this package. Its use is
5216 described below (see <ref id="shlibslocal">).
5221 <p><file>/etc/dpkg/shlibs.override</file></p>
5224 This lists global overrides. This list is normally
5225 empty. It is maintained by the local system
5231 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5234 When packages are being built, any
5235 <file>debian/shlibs</file> files are copied into the
5236 control file area of the temporary build directory and
5237 given the name <file>shlibs</file>. These files give
5238 details of any shared libraries included in the
5240 An example may help here. Let us say that the
5241 source package <tt>foo</tt> generates two binary
5242 packages, <tt>libfoo2</tt> and
5243 <tt>foo-runtime</tt>. When building the binary
5244 packages, the two packages are created in the
5245 directories <file>debian/libfoo2</file> and
5246 <file>debian/foo-runtime</file> respectively.
5247 (<file>debian/tmp</file> could be used instead of one
5248 of these.) Since <tt>libfoo2</tt> provides the
5249 <tt>libfoo</tt> shared library, it will require a
5250 <tt>shlibs</tt> file, which will be installed in
5251 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5253 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5254 when <prgn>dpkg-shlibdeps</prgn> is run on the
5256 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5258 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5259 determine whether <tt>foo-prog</tt>'s library
5260 dependencies are satisfied by any of the libraries
5261 provided by <tt>libfoo2</tt>. For this reason,
5262 <prgn>dpkg-shlibdeps</prgn> must only be run once
5263 all of the individual binary packages'
5264 <tt>shlibs</tt> files have been installed into the
5271 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5274 These are the <file>shlibs</file> files corresponding to
5275 all of the packages installed on the system, and are
5276 maintained by the relevant package maintainers.
5281 <p><file>/etc/dpkg/shlibs.default</file></p>
5284 This file lists any shared libraries whose packages
5285 have failed to provide correct <file>shlibs</file> files.
5286 It was used when the <file>shlibs</file> setup was first
5287 introduced, but it is now normally empty. It is
5288 maintained by the <tt>dpkg</tt> maintainer.
5296 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5297 <file>shlibs</file> files</heading>
5301 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5302 into your <file>debian/rules</file> file. If your package
5303 contains only compiled binaries and libraries (but no scripts),
5304 you can use a command such as:
5305 <example compact="compact">
5306 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5307 debian/tmp/usr/lib/*
5309 Otherwise, you will need to explicitly list the compiled
5310 binaries and libraries.<footnote>
5311 If you are using <tt>debhelper</tt>, the
5312 <prgn>dh_shlibdeps</prgn> program will do this work for
5313 you. It will also correctly handle multi-binary
5319 This command puts the dependency information into the
5320 <file>debian/substvars</file> file, which is then used by
5321 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5322 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5323 field in the control file for this to work.
5327 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5328 done. If it does complain you might need to create your own
5329 <file>debian/shlibs.local</file> file, as explained below (see
5330 <ref id="shlibslocal">).
5334 If you have multiple binary packages, you will need to call
5335 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5336 compiled libraries or binaries. In such a case, you will
5337 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5338 utilities to specify a different <file>substvars</file> file.
5342 If you are creating a udeb for use in the Debian Installer, you
5343 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5344 the dependency line of type <tt>udeb</tt> by adding
5345 <tt>-tudeb</tt> as option<footnote>
5346 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5347 will automatically add this option if it knows it is
5349 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5350 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5351 fall back to the regular dependency line.
5355 For more details on dpkg-shlibdeps, please see
5356 <ref id="pkg-dpkg-shlibdeps"> and
5357 <manref name="dpkg-shlibdeps" section="1">.
5362 <heading>The <file>shlibs</file> File Format</heading>
5365 Each <file>shlibs</file> file has the same format. Lines
5366 beginning with <tt>#</tt> are considered to be comments and
5367 are ignored. Each line is of the form:
5368 <example compact="compact">
5369 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5374 We will explain this by reference to the example of the
5375 <tt>zlib1g</tt> package, which (at the time of writing)
5376 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5380 <var>type</var> is an optional element that indicates the type
5381 of package for which the line is valid. The only type currently
5382 in use is <tt>udeb</tt>. The colon and space after the type are
5387 <var>library-name</var> is the name of the shared library,
5388 in this case <tt>libz</tt>. (This must match the name part
5389 of the soname, see below.)
5393 <var>soname-version</var> is the version part of the soname of
5394 the library. The soname is the thing that must exactly match
5395 for the library to be recognized by the dynamic linker, and is
5397 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5398 example, <tt>libz.so.1</tt>.<footnote>
5399 This can be determined using the command
5400 <example compact="compact">
5401 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5404 The version part is the part which comes after
5405 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5409 <var>dependencies</var> has the same syntax as a dependency
5410 field in a binary package control file. It should give
5411 details of which packages are required to satisfy a binary
5412 built against the version of the library contained in the
5413 package. See <ref id="depsyntax"> for details.
5417 In our example, if the first version of the <tt>zlib1g</tt>
5418 package which contained a minor number of at least
5419 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5420 <tt>shlibs</tt> entry for this library could say:
5421 <example compact="compact">
5422 libz 1 zlib1g (>= 1:1.1.3)
5424 The version-specific dependency is to avoid warnings from
5425 the dynamic linker about using older shared libraries with
5430 As zlib1g also provides a udeb containing the shared library,
5431 there would also be a second line:
5432 <example compact="compact">
5433 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5439 <heading>Providing a <file>shlibs</file> file</heading>
5442 If your package provides a shared library, you need to create
5443 a <file>shlibs</file> file following the format described above.
5444 It is usual to call this file <file>debian/shlibs</file> (but if
5445 you have multiple binary packages, you might want to call it
5446 <file>debian/shlibs.<var>package</var></file> instead). Then
5447 let <file>debian/rules</file> install it in the control area:
5448 <example compact="compact">
5449 install -m644 debian/shlibs debian/tmp/DEBIAN
5451 or, in the case of a multi-binary package:
5452 <example compact="compact">
5453 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5455 An alternative way of doing this is to create the
5456 <file>shlibs</file> file in the control area directly from
5457 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5458 file at all,<footnote>
5459 This is what <prgn>dh_makeshlibs</prgn> in the
5460 <tt>debhelper</tt> suite does. If your package also has a udeb
5461 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5462 automatically generate the <tt>udeb:</tt> lines if you specify
5463 the name of the udeb with the <tt>--add-udeb</tt> option.
5465 since the <file>debian/shlibs</file> file itself is ignored by
5466 <prgn>dpkg-shlibdeps</prgn>.
5470 As <prgn>dpkg-shlibdeps</prgn> reads the
5471 <file>DEBIAN/shlibs</file> files in all of the binary packages
5472 being built from this source package, all of the
5473 <file>DEBIAN/shlibs</file> files should be installed before
5474 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5479 <sect1 id="shlibslocal">
5480 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5483 This file is intended only as a <em>temporary</em> fix if
5484 your binaries or libraries depend on a library whose package
5485 does not yet provide a correct <file>shlibs</file> file.
5489 We will assume that you are trying to package a binary
5490 <tt>foo</tt>. When you try running
5491 <prgn>dpkg-shlibdeps</prgn> you get the following error
5492 message (<tt>-O</tt> displays the dependency information on
5493 <tt>stdout</tt> instead of writing it to
5494 <tt>debian/substvars</tt>, and the lines have been wrapped
5495 for ease of reading):
5496 <example compact="compact">
5497 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5498 dpkg-shlibdeps: warning: unable to find dependency
5499 information for shared library libbar (soname 1,
5500 path /usr/lib/libbar.so.1, dependency field Depends)
5501 shlibs:Depends=libc6 (>= 2.2.2-2)
5503 You can then run <prgn>ldd</prgn> on the binary to find the
5504 full location of the library concerned:
5505 <example compact="compact">
5507 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5508 libc.so.6 => /lib/libc.so.6 (0x40032000)
5509 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5511 So the <prgn>foo</prgn> binary depends on the
5512 <prgn>libbar</prgn> shared library, but no package seems to
5513 provide a <file>*.shlibs</file> file handling
5514 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5515 determine the package responsible:
5516 <example compact="compact">
5517 $ dpkg -S /usr/lib/libbar.so.1
5518 bar1: /usr/lib/libbar.so.1
5519 $ dpkg -s bar1 | grep Version
5522 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5523 is the one we are using. Now we can file a bug against the
5524 <tt>bar1</tt> package and create our own
5525 <file>debian/shlibs.local</file> to locally fix the problem.
5526 Including the following line into your
5527 <file>debian/shlibs.local</file> file:
5528 <example compact="compact">
5529 libbar 1 bar1 (>= 1.0-1)
5531 should allow the package build to work.
5535 As soon as the maintainer of <tt>bar1</tt> provides a
5536 correct <file>shlibs</file> file, you should remove this line
5537 from your <file>debian/shlibs.local</file> file. (You should
5538 probably also then have a versioned <tt>Build-Depends</tt>
5539 on <tt>bar1</tt> to help ensure that others do not have the
5540 same problem building your package.)
5549 <chapt id="opersys"><heading>The Operating System</heading>
5552 <heading>File system hierarchy</heading>
5556 <heading>File System Structure</heading>
5559 The location of all installed files and directories must
5560 comply with the Filesystem Hierarchy Standard (FHS),
5561 version 2.3, with the exceptions noted below, and except
5562 where doing so would violate other terms of Debian
5563 Policy. The following exceptions to the FHS apply:
5568 The optional rules related to user specific
5569 configuration files for applications are stored in
5570 the user's home directory are relaxed. It is
5571 recommended that such files start with the
5572 '<tt>.</tt>' character (a "dot file"), and if an
5573 application needs to create more than one dot file
5574 then the preferred placement is in a subdirectory
5575 with a name starting with a '.' character, (a "dot
5576 directory"). In this case it is recommended the
5577 configuration files not start with the '.'
5583 The requirement for amd64 to use <file>/lib64</file>
5584 for 64 bit binaries is removed.
5589 The requirement that
5590 <file>/usr/local/share/man</file> be "synonymous"
5591 with <file>/usr/local/man</file> is relaxed to a
5596 The requirement that windowmanagers with a single
5597 configuration file call it <file>system.*wmrc</file>
5598 is removed, as is the restriction that the window
5599 manager subdirectory be named identically to the
5600 window manager name itself.
5605 The requirement that boot manager configuration
5606 files live in <file>/etc</file>, or at least are
5607 symlinked there, is relaxed to a recommendation.
5614 The version of this document referred here can be
5615 found in the <tt>debian-policy</tt> package or on <url
5616 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5617 name="FHS (Debian copy)"> alongside this manual (or, if
5618 you have the <package>debian-policy</package> installed,
5620 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5621 (local copy)">). The
5622 latest version, which may be a more recent version, may
5624 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5625 Specific questions about following the standard may be
5626 asked on the <tt>debian-devel</tt> mailing list, or
5627 referred to the FHS mailing list (see the
5628 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5634 <heading>Site-specific programs</heading>
5637 As mandated by the FHS, packages must not place any
5638 files in <file>/usr/local</file>, either by putting them in
5639 the file system archive to be unpacked by <prgn>dpkg</prgn>
5640 or by manipulating them in their maintainer scripts.
5644 However, the package may create empty directories below
5645 <file>/usr/local</file> so that the system administrator knows
5646 where to place site-specific files. These are not
5647 directories <em>in</em> <file>/usr/local</file>, but are
5648 children of directories in <file>/usr/local</file>. These
5649 directories (<file>/usr/local/*/dir/</file>)
5650 should be removed on package removal if they are
5655 Note, that this applies only to directories <em>below</em>
5656 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5657 Packages must not create sub-directories in the directory
5658 <file>/usr/local</file> itself, except those listed in FHS,
5659 section 4.5. However, you may create directories below
5660 them as you wish. You must not remove any of the
5661 directories listed in 4.5, even if you created them.
5665 Since <file>/usr/local</file> can be mounted read-only from a
5666 remote server, these directories must be created and
5667 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5668 maintainer scripts and not be included in the
5669 <file>.deb</file> archive. These scripts must not fail if
5670 either of these operations fail.
5674 For example, the <tt>emacsen-common</tt> package could
5675 contain something like
5676 <example compact="compact">
5677 if [ ! -e /usr/local/share/emacs ]
5679 if mkdir /usr/local/share/emacs 2>/dev/null
5681 chown root:staff /usr/local/share/emacs
5682 chmod 2775 /usr/local/share/emacs
5686 in its <prgn>postinst</prgn> script, and
5687 <example compact="compact">
5688 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5689 rmdir /usr/local/share/emacs 2>/dev/null || true
5691 in the <prgn>prerm</prgn> script. (Note that this form is
5692 used to ensure that if the script is interrupted, the
5693 directory <file>/usr/local/share/emacs</file> will still be
5698 If you do create a directory in <file>/usr/local</file> for
5699 local additions to a package, you should ensure that
5700 settings in <file>/usr/local</file> take precedence over the
5701 equivalents in <file>/usr</file>.
5705 However, because <file>/usr/local</file> and its contents are
5706 for exclusive use of the local administrator, a package
5707 must not rely on the presence or absence of files or
5708 directories in <file>/usr/local</file> for normal operation.
5712 The <file>/usr/local</file> directory itself and all the
5713 subdirectories created by the package should (by default) have
5714 permissions 2775 (group-writable and set-group-id) and be
5715 owned by <tt>root:staff</tt>.
5720 <heading>The system-wide mail directory</heading>
5722 The system-wide mail directory is <file>/var/mail</file>. This
5723 directory is part of the base system and should not owned
5724 by any particular mail agents. The use of the old
5725 location <file>/var/spool/mail</file> is deprecated, even
5726 though the spool may still be physically located there.
5732 <heading>Users and groups</heading>
5735 <heading>Introduction</heading>
5737 The Debian system can be configured to use either plain or
5742 Some user ids (UIDs) and group ids (GIDs) are reserved
5743 globally for use by certain packages. Because some
5744 packages need to include files which are owned by these
5745 users or groups, or need the ids compiled into binaries,
5746 these ids must be used on any Debian system only for the
5747 purpose for which they are allocated. This is a serious
5748 restriction, and we should avoid getting in the way of
5749 local administration policies. In particular, many sites
5750 allocate users and/or local system groups starting at 100.
5754 Apart from this we should have dynamically allocated ids,
5755 which should by default be arranged in some sensible
5756 order, but the behavior should be configurable.
5760 Packages other than <tt>base-passwd</tt> must not modify
5761 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5762 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5767 <heading>UID and GID classes</heading>
5769 The UID and GID numbers are divided into classes as
5775 Globally allocated by the Debian project, the same
5776 on every Debian system. These ids will appear in
5777 the <file>passwd</file> and <file>group</file> files of all
5778 Debian systems, new ids in this range being added
5779 automatically as the <tt>base-passwd</tt> package is
5784 Packages which need a single statically allocated
5785 uid or gid should use one of these; their
5786 maintainers should ask the <tt>base-passwd</tt>
5794 Dynamically allocated system users and groups.
5795 Packages which need a user or group, but can have
5796 this user or group allocated dynamically and
5797 differently on each system, should use <tt>adduser
5798 --system</tt> to create the group and/or user.
5799 <prgn>adduser</prgn> will check for the existence of
5800 the user or group, and if necessary choose an unused
5801 id based on the ranges specified in
5802 <file>adduser.conf</file>.
5806 <tag>1000-29999:</tag>
5809 Dynamically allocated user accounts. By default
5810 <prgn>adduser</prgn> will choose UIDs and GIDs for
5811 user accounts in this range, though
5812 <file>adduser.conf</file> may be used to modify this
5817 <tag>30000-59999:</tag>
5822 <tag>60000-64999:</tag>
5825 Globally allocated by the Debian project, but only
5826 created on demand. The ids are allocated centrally
5827 and statically, but the actual accounts are only
5828 created on users' systems on demand.
5832 These ids are for packages which are obscure or
5833 which require many statically-allocated ids. These
5834 packages should check for and create the accounts in
5835 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5836 <prgn>adduser</prgn> if it has this facility) if
5837 necessary. Packages which are likely to require
5838 further allocations should have a "hole" left after
5839 them in the allocation, to give them room to
5844 <tag>65000-65533:</tag>
5852 User <tt>nobody</tt>. The corresponding gid refers
5853 to the group <tt>nogroup</tt>.
5860 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5861 not</em> be used, because it is the error return
5870 <sect id="sysvinit">
5871 <heading>System run levels and <file>init.d</file> scripts</heading>
5873 <sect1 id="/etc/init.d">
5874 <heading>Introduction</heading>
5877 The <file>/etc/init.d</file> directory contains the scripts
5878 executed by <prgn>init</prgn> at boot time and when the
5879 init state (or "runlevel") is changed (see <manref
5880 name="init" section="8">).
5884 There are at least two different, yet functionally
5885 equivalent, ways of handling these scripts. For the sake
5886 of simplicity, this document describes only the symbolic
5887 link method. However, it must not be assumed by maintainer
5888 scripts that this method is being used, and any automated
5889 manipulation of the various runlevel behaviors by
5890 maintainer scripts must be performed using
5891 <prgn>update-rc.d</prgn> as described below and not by
5892 manually installing or removing symlinks. For information
5893 on the implementation details of the other method,
5894 implemented in the <tt>file-rc</tt> package, please refer
5895 to the documentation of that package.
5899 These scripts are referenced by symbolic links in the
5900 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5901 runlevels, <prgn>init</prgn> looks in the directory
5902 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5903 execute, where <tt><var>n</var></tt> is the runlevel that
5904 is being changed to, or <tt>S</tt> for the boot-up
5909 The names of the links all have the form
5910 <file>S<var>mm</var><var>script</var></file> or
5911 <file>K<var>mm</var><var>script</var></file> where
5912 <var>mm</var> is a two-digit number and <var>script</var>
5913 is the name of the script (this should be the same as the
5914 name of the actual script in <file>/etc/init.d</file>).
5918 When <prgn>init</prgn> changes runlevel first the targets
5919 of the links whose names start with a <tt>K</tt> are
5920 executed, each with the single argument <tt>stop</tt>,
5921 followed by the scripts prefixed with an <tt>S</tt>, each
5922 with the single argument <tt>start</tt>. (The links are
5923 those in the <file>/etc/rc<var>n</var>.d</file> directory
5924 corresponding to the new runlevel.) The <tt>K</tt> links
5925 are responsible for killing services and the <tt>S</tt>
5926 link for starting services upon entering the runlevel.
5930 For example, if we are changing from runlevel 2 to
5931 runlevel 3, init will first execute all of the <tt>K</tt>
5932 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5933 all of the <tt>S</tt> prefixed scripts in that directory.
5934 The links starting with <tt>K</tt> will cause the
5935 referred-to file to be executed with an argument of
5936 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5941 The two-digit number <var>mm</var> is used to determine
5942 the order in which to run the scripts: low-numbered links
5943 have their scripts run first. For example, the
5944 <tt>K20</tt> scripts will be executed before the
5945 <tt>K30</tt> scripts. This is used when a certain service
5946 must be started before another. For example, the name
5947 server <prgn>bind</prgn> might need to be started before
5948 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5949 can set up its access lists. In this case, the script
5950 that starts <prgn>bind</prgn> would have a lower number
5951 than the script that starts <prgn>inn</prgn> so that it
5953 <example compact="compact">
5960 The two runlevels 0 (halt) and 6 (reboot) are slightly
5961 different. In these runlevels, the links with an
5962 <tt>S</tt> prefix are still called after those with a
5963 <tt>K</tt> prefix, but they too are called with the single
5964 argument <tt>stop</tt>.
5969 <heading>Writing the scripts</heading>
5972 Packages that include daemons for system services should
5973 place scripts in <file>/etc/init.d</file> to start or stop
5974 services at boot time or during a change of runlevel.
5975 These scripts should be named
5976 <file>/etc/init.d/<var>package</var></file>, and they should
5977 accept one argument, saying what to do:
5980 <tag><tt>start</tt></tag>
5981 <item>start the service,</item>
5983 <tag><tt>stop</tt></tag>
5984 <item>stop the service,</item>
5986 <tag><tt>restart</tt></tag>
5987 <item>stop and restart the service if it's already running,
5988 otherwise start the service</item>
5990 <tag><tt>reload</tt></tag>
5991 <item><p>cause the configuration of the service to be
5992 reloaded without actually stopping and restarting
5995 <tag><tt>force-reload</tt></tag>
5996 <item>cause the configuration to be reloaded if the
5997 service supports this, otherwise restart the
6001 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6002 <tt>force-reload</tt> options should be supported by all
6003 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6008 The <file>init.d</file> scripts must ensure that they will
6009 behave sensibly (i.e., returning success and not starting
6010 multiple copies of a service) if invoked with <tt>start</tt>
6011 when the service is already running, or with <tt>stop</tt>
6012 when it isn't, and that they don't kill unfortunately-named
6013 user processes. The best way to achieve this is usually to
6014 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6019 If a service reloads its configuration automatically (as
6020 in the case of <prgn>cron</prgn>, for example), the
6021 <tt>reload</tt> option of the <file>init.d</file> script
6022 should behave as if the configuration has been reloaded
6027 The <file>/etc/init.d</file> scripts must be treated as
6028 configuration files, either (if they are present in the
6029 package, that is, in the .deb file) by marking them as
6030 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6031 by managing them correctly in the maintainer scripts (see
6032 <ref id="config-files">). This is important since we want
6033 to give the local system administrator the chance to adapt
6034 the scripts to the local system, e.g., to disable a
6035 service without de-installing the package, or to specify
6036 some special command line options when starting a service,
6037 while making sure their changes aren't lost during the next
6042 These scripts should not fail obscurely when the
6043 configuration files remain but the package has been
6044 removed, as configuration files remain on the system after
6045 the package has been removed. Only when <prgn>dpkg</prgn>
6046 is executed with the <tt>--purge</tt> option will
6047 configuration files be removed. In particular, as the
6048 <file>/etc/init.d/<var>package</var></file> script itself is
6049 usually a <tt>conffile</tt>, it will remain on the system
6050 if the package is removed but not purged. Therefore, you
6051 should include a <tt>test</tt> statement at the top of the
6053 <example compact="compact">
6054 test -f <var>program-executed-later-in-script</var> || exit 0
6059 Often there are some variables in the <file>init.d</file>
6060 scripts whose values control the behavior of the scripts,
6061 and which a system administrator is likely to want to
6062 change. As the scripts themselves are frequently
6063 <tt>conffile</tt>s, modifying them requires that the
6064 administrator merge in their changes each time the package
6065 is upgraded and the <tt>conffile</tt> changes. To ease
6066 the burden on the system administrator, such configurable
6067 values should not be placed directly in the script.
6068 Instead, they should be placed in a file in
6069 <file>/etc/default</file>, which typically will have the same
6070 base name as the <file>init.d</file> script. This extra file
6071 should be sourced by the script when the script runs. It
6072 must contain only variable settings and comments in SUSv3
6073 <prgn>sh</prgn> format. It may either be a
6074 <tt>conffile</tt> or a configuration file maintained by
6075 the package maintainer scripts. See <ref id="config-files">
6080 To ensure that vital configurable values are always
6081 available, the <file>init.d</file> script should set default
6082 values for each of the shell variables it uses, either
6083 before sourcing the <file>/etc/default/</file> file or
6084 afterwards using something like the <tt>:
6085 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6086 script must behave sensibly and not fail if the
6087 <file>/etc/default</file> file is deleted.
6091 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6092 as temporary filesystems<footnote>
6093 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6094 options in <file>/etc/default/rcS</file>.
6095 </footnote>, so the <file>init.d</file> scripts must handle this
6096 correctly. This will typically amount to creating any required
6097 subdirectories dynamically when the <file>init.d</file> script
6098 is run, rather than including them in the package and relying on
6099 <prgn>dpkg</prgn> to create them.
6104 <heading>Interfacing with the initscript system</heading>
6107 Maintainers should use the abstraction layer provided by
6108 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6109 programs to deal with initscripts in their packages'
6110 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6111 and <prgn>postrm</prgn>.
6115 Directly managing the /etc/rc?.d links and directly
6116 invoking the <file>/etc/init.d/</file> initscripts should
6117 be done only by packages providing the initscript
6118 subsystem (such as <prgn>sysv-rc</prgn> and
6119 <prgn>file-rc</prgn>).
6123 <heading>Managing the links</heading>
6126 The program <prgn>update-rc.d</prgn> is provided for
6127 package maintainers to arrange for the proper creation and
6128 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6129 or their functional equivalent if another method is being
6130 used. This may be used by maintainers in their packages'
6131 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6135 You must not include any <file>/etc/rc<var>n</var>.d</file>
6136 symbolic links in the actual archive or manually create or
6137 remove the symbolic links in maintainer scripts; you must
6138 use the <prgn>update-rc.d</prgn> program instead. (The
6139 former will fail if an alternative method of maintaining
6140 runlevel information is being used.) You must not include
6141 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6142 in the archive either. (Only the <tt>sysvinit</tt>
6147 By default <prgn>update-rc.d</prgn> will start services in
6148 each of the multi-user state runlevels (2, 3, 4, and 5)
6149 and stop them in the halt runlevel (0), the single-user
6150 runlevel (1) and the reboot runlevel (6). The system
6151 administrator will have the opportunity to customize
6152 runlevels by simply adding, moving, or removing the
6153 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6154 symbolic links are being used, or by modifying
6155 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6160 To get the default behavior for your package, put in your
6161 <prgn>postinst</prgn> script
6162 <example compact="compact">
6163 update-rc.d <var>package</var> defaults
6165 and in your <prgn>postrm</prgn>
6166 <example compact="compact">
6167 if [ "$1" = purge ]; then
6168 update-rc.d <var>package</var> remove
6170 </example>. Note that if your package changes runlevels
6171 or priority, you may have to remove and recreate the links,
6172 since otherwise the old links may persist. Refer to the
6173 documentation of <prgn>update-rc.d</prgn>.
6177 This will use a default sequence number of 20. If it does
6178 not matter when or in which order the <file>init.d</file>
6179 script is run, use this default. If it does, then you
6180 should talk to the maintainer of the <prgn>sysvinit</prgn>
6181 package or post to <tt>debian-devel</tt>, and they will
6182 help you choose a number.
6186 For more information about using <tt>update-rc.d</tt>,
6187 please consult its man page <manref name="update-rc.d"
6193 <heading>Running initscripts</heading>
6195 The program <prgn>invoke-rc.d</prgn> is provided to make
6196 it easier for package maintainers to properly invoke an
6197 initscript, obeying runlevel and other locally-defined
6198 constraints that might limit a package's right to start,
6199 stop and otherwise manage services. This program may be
6200 used by maintainers in their packages' scripts.
6204 The package maintainer scripts must use
6205 <prgn>invoke-rc.d</prgn> to invoke the
6206 <file>/etc/init.d/*</file> initscripts, instead of
6207 calling them directly.
6211 By default, <prgn>invoke-rc.d</prgn> will pass any
6212 action requests (start, stop, reload, restart...) to the
6213 <file>/etc/init.d</file> script, filtering out requests
6214 to start or restart a service out of its intended
6219 Most packages will simply need to change:
6220 <example compact="compact">/etc/init.d/<package>
6221 <action></example> in their <prgn>postinst</prgn>
6222 and <prgn>prerm</prgn> scripts to:
6223 <example compact="compact">
6224 if which invoke-rc.d >/dev/null 2>&1; then
6225 invoke-rc.d <var>package</var> <action>
6227 /etc/init.d/<var>package</var> <action>
6233 A package should register its initscript services using
6234 <prgn>update-rc.d</prgn> before it tries to invoke them
6235 using <prgn>invoke-rc.d</prgn>. Invocation of
6236 unregistered services may fail.
6240 For more information about using
6241 <prgn>invoke-rc.d</prgn>, please consult its man page
6242 <manref name="invoke-rc.d" section="8">.
6248 <heading>Boot-time initialization</heading>
6251 There used to be another directory, <file>/etc/rc.boot</file>,
6252 which contained scripts which were run once per machine
6253 boot. This has been deprecated in favour of links from
6254 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6255 described in <ref id="/etc/init.d">. Packages must not
6256 place files in <file>/etc/rc.boot</file>.
6261 <heading>Example</heading>
6264 An example on which you can base your
6265 <file>/etc/init.d</file> scripts is found in
6266 <file>/etc/init.d/skeleton</file>.
6273 <heading>Console messages from <file>init.d</file> scripts</heading>
6276 This section describes the formats to be used for messages
6277 written to standard output by the <file>/etc/init.d</file>
6278 scripts. The intent is to improve the consistency of
6279 Debian's startup and shutdown look and feel. For this
6280 reason, please look very carefully at the details. We want
6281 the messages to have the same format in terms of wording,
6282 spaces, punctuation and case of letters.
6286 Here is a list of overall rules that should be used for
6287 messages generated by <file>/etc/init.d</file> scripts.
6293 The message should fit in one line (fewer than 80
6294 characters), start with a capital letter and end with
6295 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6299 If the script is performing some time consuming task in
6300 the background (not merely starting or stopping a
6301 program, for instance), an ellipsis (three dots:
6302 <tt>...</tt>) should be output to the screen, with no
6303 leading or tailing whitespace or line feeds.
6307 The messages should appear as if the computer is telling
6308 the user what it is doing (politely :-), but should not
6309 mention "it" directly. For example, instead of:
6310 <example compact="compact">
6311 I'm starting network daemons: nfsd mountd.
6313 the message should say
6314 <example compact="compact">
6315 Starting network daemons: nfsd mountd.
6322 <tt>init.d</tt> script should use the following standard
6323 message formats for the situations enumerated below.
6329 <p>When daemons are started</p>
6332 If the script starts one or more daemons, the output
6333 should look like this (a single line, no leading
6335 <example compact="compact">
6336 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6338 The <var>description</var> should describe the
6339 subsystem the daemon or set of daemons are part of,
6340 while <var>daemon-1</var> up to <var>daemon-n</var>
6341 denote each daemon's name (typically the file name of
6346 For example, the output of <file>/etc/init.d/lpd</file>
6348 <example compact="compact">
6349 Starting printer spooler: lpd.
6354 This can be achieved by saying
6355 <example compact="compact">
6356 echo -n "Starting printer spooler: lpd"
6357 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6360 in the script. If there are more than one daemon to
6361 start, the output should look like this:
6362 <example compact="compact">
6363 echo -n "Starting remote file system services:"
6364 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6365 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6366 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6369 This makes it possible for the user to see what is
6370 happening and when the final daemon has been started.
6371 Care should be taken in the placement of white spaces:
6372 in the example above the system administrators can
6373 easily comment out a line if they don't want to start
6374 a specific daemon, while the displayed message still
6380 <p>When a system parameter is being set</p>
6383 If you have to set up different system parameters
6384 during the system boot, you should use this format:
6385 <example compact="compact">
6386 Setting <var>parameter</var> to "<var>value</var>".
6391 You can use a statement such as the following to get
6393 <example compact="compact">
6394 echo "Setting DNS domainname to \"$domainname\"."
6399 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6400 for the left and right quotation marks. A grave accent
6401 (<tt>`</tt>) is not a quote character; neither is an
6402 apostrophe (<tt>'</tt>).
6407 <p>When a daemon is stopped or restarted</p>
6410 When you stop or restart a daemon, you should issue a
6411 message identical to the startup message, except that
6412 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6413 or <tt>Restarting</tt> respectively.
6417 For example, stopping the printer daemon will look like
6419 <example compact="compact">
6420 Stopping printer spooler: lpd.
6426 <p>When something is executed</p>
6429 There are several examples where you have to run a
6430 program at system startup or shutdown to perform a
6431 specific task, for example, setting the system's clock
6432 using <prgn>netdate</prgn> or killing all processes
6433 when the system shuts down. Your message should look
6435 <example compact="compact">
6436 Doing something very useful...done.
6438 You should print the <tt>done.</tt> immediately after
6439 the job has been completed, so that the user is
6440 informed why they have to wait. You can get this
6442 <example compact="compact">
6443 echo -n "Doing something very useful..."
6452 <p>When the configuration is reloaded</p>
6455 When a daemon is forced to reload its configuration
6456 files you should use the following format:
6457 <example compact="compact">
6458 Reloading <var>description</var> configuration...done.
6460 where <var>description</var> is the same as in the
6461 daemon starting message.
6469 <heading>Cron jobs</heading>
6472 Packages must not modify the configuration file
6473 <file>/etc/crontab</file>, and they must not modify the files in
6474 <file>/var/spool/cron/crontabs</file>.</p>
6477 If a package wants to install a job that has to be executed
6478 via cron, it should place a file with the name of the
6479 package in one or more of the following directories:
6480 <example compact="compact">
6486 As these directory names imply, the files within them are
6487 executed on an hourly, daily, weekly, or monthly basis,
6488 respectively. The exact times are listed in
6489 <file>/etc/crontab</file>.</p>
6492 All files installed in any of these directories must be
6493 scripts (e.g., shell scripts or Perl scripts) so that they
6494 can easily be modified by the local system administrator.
6495 In addition, they must be treated as configuration files.
6499 If a certain job has to be executed at some other frequency or
6500 at a specific time, the package should install a file
6501 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6502 same syntax as <file>/etc/crontab</file> and is processed by
6503 <prgn>cron</prgn> automatically. The file must also be
6504 treated as a configuration file. (Note that entries in the
6505 <file>/etc/cron.d</file> directory are not handled by
6506 <prgn>anacron</prgn>. Thus, you should only use this
6507 directory for jobs which may be skipped if the system is not
6511 The scripts or crontab entries in these directories should
6512 check if all necessary programs are installed before they
6513 try to execute them. Otherwise, problems will arise when a
6514 package was removed but not purged since configuration files
6515 are kept on the system in this situation.</p>
6519 <heading>Menus</heading>
6522 The Debian <tt>menu</tt> package provides a standard
6523 interface between packages providing applications and
6524 <em>menu programs</em> (either X window managers or
6525 text-based menu programs such as <prgn>pdmenu</prgn>).
6529 All packages that provide applications that need not be
6530 passed any special command line arguments for normal
6531 operation should register a menu entry for those
6532 applications, so that users of the <tt>menu</tt> package
6533 will automatically get menu entries in their window
6534 managers, as well in shells like <tt>pdmenu</tt>.
6538 Menu entries should follow the current menu policy.
6542 The menu policy can be found in the <tt>menu-policy</tt>
6543 files in the <tt>debian-policy</tt> package.
6544 It is also available from the Debian web mirrors at
6545 <tt><url name="/doc/packaging-manuals/menu-policy/"
6546 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6550 Please also refer to the <em>Debian Menu System</em>
6551 documentation that comes with the <package>menu</package>
6552 package for information about how to register your
6558 <heading>Multimedia handlers</heading>
6561 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6562 is a mechanism for encoding files and data streams and
6563 providing meta-information about them, in particular their
6564 type (e.g. audio or video) and format (e.g. PNG, HTML,
6569 Registration of MIME type handlers allows programs like mail
6570 user agents and web browsers to invoke these handlers to
6571 view, edit or display MIME types they don't support directly.
6575 Packages which provide the ability to view/show/play,
6576 compose, edit or print MIME types should register themselves
6577 as such following the current MIME support policy.
6581 The MIME support policy can be found in the <tt>mime-policy</tt>
6582 files in the <tt>debian-policy</tt> package.
6583 It is also available from the Debian web mirrors at
6584 <tt><url name="/doc/packaging-manuals/mime-policy/"
6585 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6591 <heading>Keyboard configuration</heading>
6594 To achieve a consistent keyboard configuration so that all
6595 applications interpret a keyboard event the same way, all
6596 programs in the Debian distribution must be configured to
6597 comply with the following guidelines.
6601 The following keys must have the specified interpretations:
6604 <tag><tt><--</tt></tag>
6605 <item>delete the character to the left of the cursor</item>
6607 <tag><tt>Delete</tt></tag>
6608 <item>delete the character to the right of the cursor</item>
6610 <tag><tt>Control+H</tt></tag>
6611 <item>emacs: the help prefix</item>
6614 The interpretation of any keyboard events should be
6615 independent of the terminal that is used, be it a virtual
6616 console, an X terminal emulator, an rlogin/telnet session,
6621 The following list explains how the different programs
6622 should be set up to achieve this:
6628 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6632 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6636 X translations are set up to make
6637 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6638 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6639 is the vt220 escape code for the "delete character"
6640 key). This must be done by loading the X resources
6641 using <prgn>xrdb</prgn> on all local X displays, not
6642 using the application defaults, so that the
6643 translation resources used correspond to the
6644 <prgn>xmodmap</prgn> settings.
6648 The Linux console is configured to make
6649 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6650 generate <tt>ESC [ 3 ~</tt>.
6654 X applications are configured so that <tt><</tt>
6655 deletes left, and <tt>Delete</tt> deletes right. Motif
6656 applications already work like this.
6660 Terminals should have <tt>stty erase ^?</tt> .
6664 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6665 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6666 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6670 Emacs is programmed to map <tt>KB_Backspace</tt> or
6671 the <tt>stty erase</tt> character to
6672 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6673 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6674 <tt>^H</tt> to <tt>help</tt> as always.
6678 Other applications use the <tt>stty erase</tt>
6679 character and <tt>kdch1</tt> for the two delete keys,
6680 with ASCII DEL being "delete previous character" and
6681 <tt>kdch1</tt> being "delete character under
6689 This will solve the problem except for the following
6696 Some terminals have a <tt><--</tt> key that cannot
6697 be made to produce anything except <tt>^H</tt>. On
6698 these terminals Emacs help will be unavailable on
6699 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6700 character takes precedence in Emacs, and has been set
6701 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6702 available) can be used instead.
6706 Some operating systems use <tt>^H</tt> for <tt>stty
6707 erase</tt>. However, modern telnet versions and all
6708 rlogin versions propagate <tt>stty</tt> settings, and
6709 almost all UNIX versions honour <tt>stty erase</tt>.
6710 Where the <tt>stty</tt> settings are not propagated
6711 correctly, things can be made to work by using
6712 <tt>stty</tt> manually.
6716 Some systems (including previous Debian versions) use
6717 <prgn>xmodmap</prgn> to arrange for both
6718 <tt><--</tt> and <tt>Delete</tt> to generate
6719 <tt>KB_Delete</tt>. We can change the behavior of
6720 their X clients using the same X resources that we use
6721 to do it for our own clients, or configure our clients
6722 using their resources when things are the other way
6723 around. On displays configured like this
6724 <tt>Delete</tt> will not work, but <tt><--</tt>
6729 Some operating systems have different <tt>kdch1</tt>
6730 settings in their <tt>terminfo</tt> database for
6731 <tt>xterm</tt> and others. On these systems the
6732 <tt>Delete</tt> key will not work correctly when you
6733 log in from a system conforming to our policy, but
6734 <tt><--</tt> will.
6741 <heading>Environment variables</heading>
6744 A program must not depend on environment variables to get
6745 reasonable defaults. (That's because these environment
6746 variables would have to be set in a system-wide
6747 configuration file like <file>/etc/profile</file>, which is not
6748 supported by all shells.)
6752 If a program usually depends on environment variables for its
6753 configuration, the program should be changed to fall back to
6754 a reasonable default configuration if these environment
6755 variables are not present. If this cannot be done easily
6756 (e.g., if the source code of a non-free program is not
6757 available), the program must be replaced by a small
6758 "wrapper" shell script which sets the environment variables
6759 if they are not already defined, and calls the original program.
6763 Here is an example of a wrapper script for this purpose:
6765 <example compact="compact">
6767 BAR=${BAR:-/var/lib/fubar}
6769 exec /usr/lib/foo/foo "$@"
6774 Furthermore, as <file>/etc/profile</file> is a configuration
6775 file of the <prgn>base-files</prgn> package, other packages must
6776 not put any environment variables or other commands into that
6781 <sect id="doc-base">
6782 <heading>Registering Documents using doc-base</heading>
6785 The <package>doc-base</package> package implements a
6786 flexible mechanism for handling and presenting
6787 documentation. The recommended practice is for every Debian
6788 package that provides online documentation (other than just
6789 manual pages) to register these documents with
6790 <package>doc-base</package> by installing a
6791 <package>doc-base</package> control file via the
6792 <prgn/install-docs/ script at installation time and
6793 de-register the manuals again when the package is removed.
6796 Please refer to the documentation that comes with the
6797 <package>doc-base</package> package for information and
6806 <heading>Files</heading>
6809 <heading>Binaries</heading>
6812 Two different packages must not install programs with
6813 different functionality but with the same filenames. (The
6814 case of two programs having the same functionality but
6815 different implementations is handled via "alternatives" or
6816 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6817 <ref id="conflicts"> respectively.) If this case happens,
6818 one of the programs must be renamed. The maintainers should
6819 report this to the <tt>debian-devel</tt> mailing list and
6820 try to find a consensus about which program will have to be
6821 renamed. If a consensus cannot be reached, <em>both</em>
6822 programs must be renamed.
6826 By default, when a package is being built, any binaries
6827 created should include debugging information, as well as
6828 being compiled with optimization. You should also turn on
6829 as many reasonable compilation warnings as possible; this
6830 makes life easier for porters, who can then look at build
6831 logs for possible problems. For the C programming language,
6832 this means the following compilation parameters should be
6834 <example compact="compact">
6836 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6838 INSTALL = install -s # (or use strip on the files in debian/tmp)
6843 Note that by default all installed binaries should be stripped,
6844 either by using the <tt>-s</tt> flag to
6845 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6846 the binaries after they have been copied into
6847 <file>debian/tmp</file> but before the tree is made into a
6852 Although binaries in the build tree should be compiled with
6853 debugging information by default, it can often be difficult to
6854 debug programs if they are also subjected to compiler
6855 optimization. For this reason, it is recommended to support the
6856 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6857 (see <ref id="debianrules-options">). This variable can contain
6858 several flags to change how a package is compiled and built.
6862 It is up to the package maintainer to decide what
6863 compilation options are best for the package. Certain
6864 binaries (such as computationally-intensive programs) will
6865 function better with certain flags (<tt>-O3</tt>, for
6866 example); feel free to use them. Please use good judgment
6867 here. Don't use flags for the sake of it; only use them
6868 if there is good reason to do so. Feel free to override
6869 the upstream author's ideas about which compilation
6870 options are best: they are often inappropriate for our
6876 <sect id="libraries">
6877 <heading>Libraries</heading>
6880 If the package is <strong>architecture: any</strong>, then
6881 the shared library compilation and linking flags must have
6882 <tt>-fPIC</tt>, or the package shall not build on some of
6883 the supported architectures<footnote>
6885 If you are using GCC, <tt>-fPIC</tt> produces code with
6886 relocatable position independent code, which is required for
6887 most architectures to create a shared library, with i386 and
6888 perhaps some others where non position independent code is
6889 permitted in a shared library.
6892 Position independent code may have a performance penalty,
6893 especially on <tt>i386</tt>. However, in most cases the
6894 speed penalty must be measured against the memory wasted on
6895 the few architectures where non position independent code is
6898 </footnote>. Any exception to this rule must be discussed on
6899 the mailing list <em>debian-devel@lists.debian.org</em>, and
6900 a rough consensus obtained. The reasons for not compiling
6901 with <tt>-fPIC</tt> flag must be recorded in the file
6902 <tt>README.Debian</tt>, and care must be taken to either
6903 restrict the architecture or arrange for <tt>-fPIC</tt> to
6904 be used on architectures where it is required.<footnote>
6906 Some of the reasons why this might be required is if the
6907 library contains hand crafted assembly code that is not
6908 relocatable, the speed penalty is excessive for compute
6909 intensive libs, and similar reasons.
6914 As to the static libraries, the common case is not to have
6915 relocatable code, since there is no benefit, unless in specific
6916 cases; therefore the static version must not be compiled
6917 with the <tt>-fPIC</tt> flag. Any exception to this rule
6918 should be discussed on the mailing list
6919 <em>debian-devel@lists.debian.org</em>, and the reasons for
6920 compiling with the <tt>-fPIC</tt> flag must be recorded in
6921 the file <tt>README.Debian</tt>. <footnote>
6923 Some of the reasons for linking static libraries with
6924 the <tt>-fPIC</tt> flag are if, for example, one needs a
6925 Perl API for a library that is under rapid development,
6926 and has an unstable API, so shared libraries are
6927 pointless at this phase of the library's development. In
6928 that case, since Perl needs a library with relocatable
6929 code, it may make sense to create a static library with
6930 relocatable code. Another reason cited is if you are
6931 distilling various libraries into a common shared
6932 library, like <tt>mklibs</tt> does in the Debian
6938 In other words, if both a shared and a static library is
6939 being built, each source unit (<tt>*.c</tt>, for example,
6940 for C files) will need to be compiled twice, for the normal
6944 You must specify the gcc option <tt>-D_REENTRANT</tt>
6945 when building a library (either static or shared) to make
6946 the library compatible with LinuxThreads.
6950 Although not enforced by the build tools, shared libraries
6951 must be linked against all libraries that they use symbols from
6952 in the same way that binaries are. This ensures the correct
6953 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6954 system and guarantees that all libraries can be safely opened
6955 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6956 option <tt>-Wl,-z,defs</tt> when building a shared library.
6957 Since this option enforces symbol resolution at build time,
6958 a missing library reference will be caught early as a fatal
6963 All installed shared libraries should be stripped with
6964 <example compact="compact">
6965 strip --strip-unneeded <var>your-lib</var>
6967 (The option <tt>--strip-unneeded</tt> makes
6968 <prgn>strip</prgn> remove only the symbols which aren't
6969 needed for relocation processing.) Shared libraries can
6970 function perfectly well when stripped, since the symbols for
6971 dynamic linking are in a separate part of the ELF object
6973 You might also want to use the options
6974 <tt>--remove-section=.comment</tt> and
6975 <tt>--remove-section=.note</tt> on both shared libraries
6976 and executables, and <tt>--strip-debug</tt> on static
6982 Note that under some circumstances it may be useful to
6983 install a shared library unstripped, for example when
6984 building a separate package to support debugging.
6988 Shared object files (often <file>.so</file> files) that are not
6989 public libraries, that is, they are not meant to be linked
6990 to by third party executables (binaries of other packages),
6991 should be installed in subdirectories of the
6992 <file>/usr/lib</file> directory. Such files are exempt from the
6993 rules that govern ordinary shared libraries, except that
6994 they must not be installed executable and should be
6996 A common example are the so-called "plug-ins",
6997 internal shared objects that are dynamically loaded by
6998 programs using <manref name="dlopen" section="3">.
7003 An ever increasing number of packages are using
7004 <prgn>libtool</prgn> to do their linking. The latest GNU
7005 libtools (>= 1.3a) can take advantage of the metadata in the
7006 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7007 files). The main advantage of <prgn>libtool</prgn>'s
7008 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7009 store and subsequently access metadata with respect to the
7010 libraries it builds. <prgn>libtool</prgn> will search for
7011 those files, which contain a lot of useful information about
7012 a library (such as library dependency information for static
7013 linking). Also, they're <em>essential</em> for programs
7014 using <tt>libltdl</tt>.<footnote>
7015 Although <prgn>libtool</prgn> is fully capable of
7016 linking against shared libraries which don't have
7017 <tt>.la</tt> files, as it is a mere shell script it can
7018 add considerably to the build time of a
7019 <prgn>libtool</prgn>-using package if that shell script
7020 has to derive all this information from first principles
7021 for each library every time it is linked. With the
7022 advent of <prgn>libtool</prgn> version 1.4 (and to a
7023 lesser extent <prgn>libtool</prgn> version 1.3), the
7024 <file>.la</file> files also store information about
7025 inter-library dependencies which cannot necessarily be
7026 derived after the <file>.la</file> file is deleted.
7031 Packages that use <prgn>libtool</prgn> to create shared
7032 libraries should include the <file>.la</file> files in the
7033 <tt>-dev</tt> package, unless the package relies on
7034 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7035 the <tt>.la</tt> files must go in the run-time library
7040 You must make sure that you use only released versions of
7041 shared libraries to build your packages; otherwise other
7042 users will not be able to run your binaries
7043 properly. Producing source packages that depend on
7044 unreleased compilers is also usually a bad
7051 <heading>Shared libraries</heading>
7053 This section has moved to <ref id="sharedlibs">.
7059 <heading>Scripts</heading>
7062 All command scripts, including the package maintainer
7063 scripts inside the package and used by <prgn>dpkg</prgn>,
7064 should have a <tt>#!</tt> line naming the shell to be used
7069 In the case of Perl scripts this should be
7070 <tt>#!/usr/bin/perl</tt>.
7074 When scripts are installed into a directory in the system
7075 PATH, the script name should not include an extension such
7076 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7077 language currently used to implement it.
7080 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7081 should almost certainly start with <tt>set -e</tt> so that
7082 errors are detected. Every script should use
7083 <tt>set -e</tt> or check the exit status of <em>every</em>
7088 Scripts may assume that <file>/bin/sh</file> implements the
7089 SUSv3 Shell Command Language<footnote>
7090 Single UNIX Specification, version 3, which is also IEEE
7091 1003.1-2004 (POSIX), and is available on the World Wide Web
7092 from <url id="http://www.unix.org/version3/online.html"
7093 name="The Open Group"> after free
7094 registration.</footnote>
7095 plus the following additional features not mandated by
7097 These features are in widespread use in the Linux community
7098 and are implemented in all of bash, dash, and ksh, the most
7099 common shells users may wish to use as <file>/bin/sh</file>.
7102 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7103 must not generate a newline.</item>
7104 <item><tt>test</tt>, if implemented as a shell built-in, must
7105 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7107 <item><tt>local</tt> to create a scoped variable must be
7108 supported, including listing multiple variables in a single
7109 local command and assigning a value to a variable at the
7110 same time as localizing it. <tt>local</tt> may or
7111 may not preserve the variable value from an outer scope if
7112 no assignment is present. Uses such as:
7116 # ... use a, b, c, d ...
7119 must be supported and must set the value of <tt>c</tt> to
7123 If a shell script requires non-SUSv3 features from the shell
7124 interpreter other than those listed above, the appropriate shell
7125 must be specified in the first line of the script (e.g.,
7126 <tt>#!/bin/bash</tt>) and the package must depend on the package
7127 providing the shell (unless the shell package is marked
7128 "Essential", as in the case of <prgn>bash</prgn>).
7132 You may wish to restrict your script to SUSv3 features plus the
7133 above set when possible so that it may use <file>/bin/sh</file>
7134 as its interpreter. If your script works with <prgn>dash</prgn>
7135 (originally called <prgn>ash</prgn>), it probably complies with
7136 the above requirements, but if you are in doubt, use
7137 <file>/bin/bash</file>.
7141 Perl scripts should check for errors when making any
7142 system calls, including <tt>open</tt>, <tt>print</tt>,
7143 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7147 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7148 scripting languages. See <em>Csh Programming Considered
7149 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7150 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7151 If an upstream package comes with <prgn>csh</prgn> scripts
7152 then you must make sure that they start with
7153 <tt>#!/bin/csh</tt> and make your package depend on the
7154 <prgn>c-shell</prgn> virtual package.
7158 Any scripts which create files in world-writeable
7159 directories (e.g., in <file>/tmp</file>) must use a
7160 mechanism which will fail atomically if a file with the same
7161 name already exists.
7165 The Debian base system provides the <prgn>tempfile</prgn>
7166 and <prgn>mktemp</prgn> utilities for use by scripts for
7173 <heading>Symbolic links</heading>
7176 In general, symbolic links within a top-level directory
7177 should be relative, and symbolic links pointing from one
7178 top-level directory into another should be absolute. (A
7179 top-level directory is a sub-directory of the root
7180 directory <file>/</file>.)
7184 In addition, symbolic links should be specified as short as
7185 possible, i.e., link targets like <file>foo/../bar</file> are
7190 Note that when creating a relative link using
7191 <prgn>ln</prgn> it is not necessary for the target of the
7192 link to exist relative to the working directory you're
7193 running <prgn>ln</prgn> from, nor is it necessary to change
7194 directory to the directory where the link is to be made.
7195 Simply include the string that should appear as the target
7196 of the link (this will be a pathname relative to the
7197 directory in which the link resides) as the first argument
7202 For example, in your <prgn>Makefile</prgn> or
7203 <file>debian/rules</file>, you can do things like:
7204 <example compact="compact">
7205 ln -fs gcc $(prefix)/bin/cc
7206 ln -fs gcc debian/tmp/usr/bin/cc
7207 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7208 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7213 A symbolic link pointing to a compressed file should always
7214 have the same file extension as the referenced file. (For
7215 example, if a file <file>foo.gz</file> is referenced by a
7216 symbolic link, the filename of the link has to end with
7217 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7222 <heading>Device files</heading>
7225 Packages must not include device files in the package file
7230 If a package needs any special device files that are not
7231 included in the base system, it must call
7232 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7233 after notifying the user<footnote>
7234 This notification could be done via a (low-priority)
7235 debconf message, or an echo (printf) statement.
7240 Packages must not remove any device files in the
7241 <prgn>postrm</prgn> or any other script. This is left to the
7242 system administrator.
7246 Debian uses the serial devices
7247 <file>/dev/ttyS*</file>. Programs using the old
7248 <file>/dev/cu*</file> devices should be changed to use
7249 <file>/dev/ttyS*</file>.
7253 <sect id="config-files">
7254 <heading>Configuration files</heading>
7257 <heading>Definitions</heading>
7261 <tag>configuration file</tag>
7263 A file that affects the operation of a program, or
7264 provides site- or host-specific information, or
7265 otherwise customizes the behavior of a program.
7266 Typically, configuration files are intended to be
7267 modified by the system administrator (if needed or
7268 desired) to conform to local policy or to provide
7269 more useful site-specific behavior.
7272 <tag><tt>conffile</tt></tag>
7274 A file listed in a package's <tt>conffiles</tt>
7275 file, and is treated specially by <prgn>dpkg</prgn>
7276 (see <ref id="configdetails">).
7282 The distinction between these two is important; they are
7283 not interchangeable concepts. Almost all
7284 <tt>conffile</tt>s are configuration files, but many
7285 configuration files are not <tt>conffiles</tt>.
7289 As noted elsewhere, <file>/etc/init.d</file> scripts,
7290 <file>/etc/default</file> files, scripts installed in
7291 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7292 configuration installed in <file>/etc/cron.d</file> must be
7293 treated as configuration files. In general, any script that
7294 embeds configuration information is de-facto a configuration
7295 file and should be treated as such.
7300 <heading>Location</heading>
7303 Any configuration files created or used by your package
7304 must reside in <file>/etc</file>. If there are several,
7305 consider creating a subdirectory of <file>/etc</file>
7306 named after your package.
7310 If your package creates or uses configuration files
7311 outside of <file>/etc</file>, and it is not feasible to modify
7312 the package to use <file>/etc</file> directly, put the files
7313 in <file>/etc</file> and create symbolic links to those files
7314 from the location that the package requires.
7319 <heading>Behavior</heading>
7322 Configuration file handling must conform to the following
7324 <list compact="compact">
7326 local changes must be preserved during a package
7330 configuration files must be preserved when the
7331 package is removed, and only deleted when the
7338 The easy way to achieve this behavior is to make the
7339 configuration file a <tt>conffile</tt>. This is
7340 appropriate only if it is possible to distribute a default
7341 version that will work for most installations, although
7342 some system administrators may choose to modify it. This
7343 implies that the default version will be part of the
7344 package distribution, and must not be modified by the
7345 maintainer scripts during installation (or at any other
7350 In order to ensure that local changes are preserved
7351 correctly, no package may contain or make hard links to
7352 conffiles.<footnote>
7353 Rationale: There are two problems with hard links.
7354 The first is that some editors break the link while
7355 editing one of the files, so that the two files may
7356 unwittingly become unlinked and different. The second
7357 is that <prgn>dpkg</prgn> might break the hard link
7358 while upgrading <tt>conffile</tt>s.
7363 The other way to do it is via the maintainer scripts. In
7364 this case, the configuration file must not be listed as a
7365 <tt>conffile</tt> and must not be part of the package
7366 distribution. If the existence of a file is required for
7367 the package to be sensibly configured it is the
7368 responsibility of the package maintainer to provide
7369 maintainer scripts which correctly create, update and
7370 maintain the file and remove it on purge. (See <ref
7371 id="maintainerscripts"> for more information.) These
7372 scripts must be idempotent (i.e., must work correctly if
7373 <prgn>dpkg</prgn> needs to re-run them due to errors
7374 during installation or removal), must cope with all the
7375 variety of ways <prgn>dpkg</prgn> can call maintainer
7376 scripts, must not overwrite or otherwise mangle the user's
7377 configuration without asking, must not ask unnecessary
7378 questions (particularly during upgrades), and must
7379 otherwise be good citizens.
7383 The scripts are not required to configure every possible
7384 option for the package, but only those necessary to get
7385 the package running on a given system. Ideally the
7386 sysadmin should not have to do any configuration other
7387 than that done (semi-)automatically by the
7388 <prgn>postinst</prgn> script.
7392 A common practice is to create a script called
7393 <file><var>package</var>-configure</file> and have the
7394 package's <prgn>postinst</prgn> call it if and only if the
7395 configuration file does not already exist. In certain
7396 cases it is useful for there to be an example or template
7397 file which the maintainer scripts use. Such files should
7398 be in <file>/usr/share/<var>package</var></file> or
7399 <file>/usr/lib/<var>package</var></file> (depending on whether
7400 they are architecture-independent or not). There should
7401 be symbolic links to them from
7402 <file>/usr/share/doc/<var>package</var>/examples</file> if
7403 they are examples, and should be perfectly ordinary
7404 <prgn>dpkg</prgn>-handled files (<em>not</em>
7405 configuration files).
7409 These two styles of configuration file handling must
7410 not be mixed, for that way lies madness:
7411 <prgn>dpkg</prgn> will ask about overwriting the file
7412 every time the package is upgraded.
7417 <heading>Sharing configuration files</heading>
7420 Packages which specify the same file as a
7421 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7422 with each other. (This is an instance of the general rule
7423 about not sharing files. Note that neither alternatives
7424 nor diversions are likely to be appropriate in this case;
7425 in particular, <prgn>dpkg</prgn> does not handle diverted
7426 <tt>conffile</tt>s well.)
7430 The maintainer scripts must not alter a <tt>conffile</tt>
7431 of <em>any</em> package, including the one the scripts
7436 If two or more packages use the same configuration file
7437 and it is reasonable for both to be installed at the same
7438 time, one of these packages must be defined as
7439 <em>owner</em> of the configuration file, i.e., it will be
7440 the package which handles that file as a configuration
7441 file. Other packages that use the configuration file must
7442 depend on the owning package if they require the
7443 configuration file to operate. If the other package will
7444 use the configuration file if present, but is capable of
7445 operating without it, no dependency need be declared.
7449 If it is desirable for two or more related packages to
7450 share a configuration file <em>and</em> for all of the
7451 related packages to be able to modify that configuration
7452 file, then the following should be done:
7453 <enumlist compact="compact">
7455 One of the related packages (the "owning" package)
7456 will manage the configuration file with maintainer
7457 scripts as described in the previous section.
7460 The owning package should also provide a program
7461 that the other packages may use to modify the
7465 The related packages must use the provided program
7466 to make any desired modifications to the
7467 configuration file. They should either depend on
7468 the core package to guarantee that the configuration
7469 modifier program is available or accept gracefully
7470 that they cannot modify the configuration file if it
7471 is not. (This is in addition to the fact that the
7472 configuration file may not even be present in the
7479 Sometimes it's appropriate to create a new package which
7480 provides the basic infrastructure for the other packages
7481 and which manages the shared configuration files. (The
7482 <tt>sgml-base</tt> package is a good example.)
7487 <heading>User configuration files ("dotfiles")</heading>
7490 The files in <file>/etc/skel</file> will automatically be
7491 copied into new user accounts by <prgn>adduser</prgn>.
7492 No other program should reference the files in
7493 <file>/etc/skel</file>.
7497 Therefore, if a program needs a dotfile to exist in
7498 advance in <file>$HOME</file> to work sensibly, that dotfile
7499 should be installed in <file>/etc/skel</file> and treated as a
7504 However, programs that require dotfiles in order to
7505 operate sensibly are a bad thing, unless they do create
7506 the dotfiles themselves automatically.
7510 Furthermore, programs should be configured by the Debian
7511 default installation to behave as closely to the upstream
7512 default behavior as possible.
7516 Therefore, if a program in a Debian package needs to be
7517 configured in some way in order to operate sensibly, that
7518 should be done using a site-wide configuration file placed
7519 in <file>/etc</file>. Only if the program doesn't support a
7520 site-wide default configuration and the package maintainer
7521 doesn't have time to add it may a default per-user file be
7522 placed in <file>/etc/skel</file>.
7526 <file>/etc/skel</file> should be as empty as we can make it.
7527 This is particularly true because there is no easy (or
7528 necessarily desirable) mechanism for ensuring that the
7529 appropriate dotfiles are copied into the accounts of
7530 existing users when a package is installed.
7536 <heading>Log files</heading>
7538 Log files should usually be named
7539 <file>/var/log/<var>package</var>.log</file>. If you have many
7540 log files, or need a separate directory for permission
7541 reasons (<file>/var/log</file> is writable only by
7542 <file>root</file>), you should usually create a directory named
7543 <file>/var/log/<var>package</var></file> and place your log
7548 Log files must be rotated occasionally so that they don't
7549 grow indefinitely; the best way to do this is to drop a log
7550 rotation configuration file into the directory
7551 <file>/etc/logrotate.d</file> and use the facilities provided by
7552 logrotate.<footnote>
7554 The traditional approach to log files has been to set up
7555 <em>ad hoc</em> log rotation schemes using simple shell
7556 scripts and cron. While this approach is highly
7557 customizable, it requires quite a lot of sysadmin work.
7558 Even though the original Debian system helped a little
7559 by automatically installing a system which can be used
7560 as a template, this was deemed not enough.
7564 The use of <prgn>logrotate</prgn>, a program developed
7565 by Red Hat, is better, as it centralizes log management.
7566 It has both a configuration file
7567 (<file>/etc/logrotate.conf</file>) and a directory where
7568 packages can drop their individual log rotation
7569 configurations (<file>/etc/logrotate.d</file>).
7572 Here is a good example for a logrotate config
7573 file (for more information see <manref name="logrotate"
7575 <example compact="compact">
7576 /var/log/foo/*.log {
7581 /etc/init.d/foo force-reload
7585 This rotates all files under <file>/var/log/foo</file>, saves 12
7586 compressed generations, and forces the daemon to reload its
7587 configuration information after the log rotation.
7591 Log files should be removed when the package is
7592 purged (but not when it is only removed). This should be
7593 done by the <prgn>postrm</prgn> script when it is called
7594 with the argument <tt>purge</tt> (see <ref
7595 id="removedetails">).
7600 <heading>Permissions and owners</heading>
7603 The rules in this section are guidelines for general use.
7604 If necessary you may deviate from the details below.
7605 However, if you do so you must make sure that what is done
7606 is secure and you should try to be as consistent as possible
7607 with the rest of the system. You should probably also
7608 discuss it on <prgn>debian-devel</prgn> first.
7612 Files should be owned by <tt>root:root</tt>, and made
7613 writable only by the owner and universally readable (and
7614 executable, if appropriate), that is mode 644 or 755.
7618 Directories should be mode 755 or (for group-writability)
7619 mode 2775. The ownership of the directory should be
7620 consistent with its mode: if a directory is mode 2775, it
7621 should be owned by the group that needs write access to
7624 When a package is upgraded, and the owner or permissions
7625 of a file included in the package has changed, dpkg
7626 arranges for the ownership and permissions to be
7627 correctly set upon installation. However, this does not
7628 extend to directories; the permissions and ownership of
7629 directories already on the system does not change on
7630 install or upgrade of packages. This makes sense, since
7631 otherwise common directories like <tt>/usr</tt> would
7632 always be in flux. To correctly change permissions of a
7633 directory the package owns, explicit action is required,
7634 usually in the <tt>postinst</tt> script. Care must be
7635 taken to handle downgrades as well, in that case.
7642 Setuid and setgid executables should be mode 4755 or 2755
7643 respectively, and owned by the appropriate user or group.
7644 They should not be made unreadable (modes like 4711 or
7645 2711 or even 4111); doing so achieves no extra security,
7646 because anyone can find the binary in the freely available
7647 Debian package; it is merely inconvenient. For the same
7648 reason you should not restrict read or execute permissions
7649 on non-set-id executables.
7653 Some setuid programs need to be restricted to particular
7654 sets of users, using file permissions. In this case they
7655 should be owned by the uid to which they are set-id, and by
7656 the group which should be allowed to execute them. They
7657 should have mode 4754; again there is no point in making
7658 them unreadable to those users who must not be allowed to
7663 It is possible to arrange that the system administrator can
7664 reconfigure the package to correspond to their local
7665 security policy by changing the permissions on a binary:
7666 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7667 described below.<footnote>
7668 Ordinary files installed by <prgn>dpkg</prgn> (as
7669 opposed to <tt>conffile</tt>s and other similar objects)
7670 normally have their permissions reset to the distributed
7671 permissions when the package is reinstalled. However,
7672 the use of <prgn>dpkg-statoverride</prgn> overrides this
7673 default behavior. If you use this method, you should
7674 remember to describe <prgn>dpkg-statoverride</prgn> in
7675 the package documentation; being a relatively new
7676 addition to Debian, it is probably not yet well-known.
7678 Another method you should consider is to create a group for
7679 people allowed to use the program(s) and make any setuid
7680 executables executable only by that group.
7684 If you need to create a new user or group for your package
7685 there are two possibilities. Firstly, you may need to
7686 make some files in the binary package be owned by this
7687 user or group, or you may need to compile the user or
7688 group id (rather than just the name) into the binary
7689 (though this latter should be avoided if possible, as in
7690 this case you need a statically allocated id).</p>
7693 If you need a statically allocated id, you must ask for a
7694 user or group id from the <tt>base-passwd</tt> maintainer,
7695 and must not release the package until you have been
7696 allocated one. Once you have been allocated one you must
7697 either make the package depend on a version of the
7698 <tt>base-passwd</tt> package with the id present in
7699 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7700 your package to create the user or group itself with the
7701 correct id (using <tt>adduser</tt>) in its
7702 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7703 the <prgn>postinst</prgn> is to be preferred if it is
7704 possible, otherwise a pre-dependency will be needed on the
7705 <tt>adduser</tt> package.)
7709 On the other hand, the program might be able to determine
7710 the uid or gid from the user or group name at runtime, so
7711 that a dynamically allocated id can be used. In this case
7712 you should choose an appropriate user or group name,
7713 discussing this on <prgn>debian-devel</prgn> and checking
7714 with the <package/base-passwd/ maintainer that it is unique and that
7715 they do not wish you to use a statically allocated id
7716 instead. When this has been checked you must arrange for
7717 your package to create the user or group if necessary using
7718 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7719 <prgn>postinst</prgn> script (again, the latter is to be
7720 preferred if it is possible).
7724 Note that changing the numeric value of an id associated
7725 with a name is very difficult, and involves searching the
7726 file system for all appropriate files. You need to think
7727 carefully whether a static or dynamic id is required, since
7728 changing your mind later will cause problems.
7731 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7733 This section is not intended as policy, but as a
7734 description of the use of <prgn>dpkg-statoverride</prgn>.
7738 If a system administrator wishes to have a file (or
7739 directory or other such thing) installed with owner and
7740 permissions different from those in the distributed Debian
7741 package, they can use the <prgn>dpkg-statoverride</prgn>
7742 program to instruct <prgn>dpkg</prgn> to use the different
7743 settings every time the file is installed. Thus the
7744 package maintainer should distribute the files with their
7745 normal permissions, and leave it for the system
7746 administrator to make any desired changes. For example, a
7747 daemon which is normally required to be setuid root, but
7748 in certain situations could be used without being setuid,
7749 should be installed setuid in the <tt>.deb</tt>. Then the
7750 local system administrator can change this if they wish.
7751 If there are two standard ways of doing it, the package
7752 maintainer can use <tt>debconf</tt> to find out the
7753 preference, and call <prgn>dpkg-statoverride</prgn> in the
7754 maintainer script if necessary to accommodate the system
7755 administrator's choice. Care must be taken during
7756 upgrades to not override an existing setting.
7760 Given the above, <prgn>dpkg-statoverride</prgn> is
7761 essentially a tool for system administrators and would not
7762 normally be needed in the maintainer scripts. There is
7763 one type of situation, though, where calls to
7764 <prgn>dpkg-statoverride</prgn> would be needed in the
7765 maintainer scripts, and that involves packages which use
7766 dynamically allocated user or group ids. In such a
7767 situation, something like the following idiom can be very
7768 helpful in the package's <prgn>postinst</prgn>, where
7769 <tt>sysuser</tt> is a dynamically allocated id:
7771 for i in /usr/bin/foo /usr/sbin/bar
7773 # only do something when no setting exists
7774 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7776 #include: debconf processing, question about foo and bar
7777 if [ "$RET" = "true" ] ; then
7778 dpkg-statoverride --update --add sysuser root 4755 $i
7783 The corresponding code to remove the override when the package
7786 for i in /usr/bin/foo /usr/sbin/bar
7788 if dpkg-statoverride --list $i >/dev/null 2>&1
7790 dpkg-statoverride --remove $i
7800 <chapt id="customized-programs">
7801 <heading>Customized programs</heading>
7803 <sect id="arch-spec">
7804 <heading>Architecture specification strings</heading>
7807 If a program needs to specify an <em>architecture specification
7808 string</em> in some place, it should select one of the
7809 strings provided by <tt>dpkg-architecture -L</tt>. The
7810 strings are in the format
7811 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7812 is sometimes elided, as when the OS is Linux.<footnote>
7813 <p>Currently, the strings are:
7814 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7815 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7816 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7817 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7818 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7819 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7820 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7821 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7822 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7823 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7824 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7825 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7826 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7827 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7828 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7829 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7830 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7831 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7832 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7833 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7834 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7835 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7836 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7837 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7838 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7839 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7840 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7841 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7842 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7843 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7844 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7845 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7846 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7847 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7848 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7849 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7850 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7856 Note that we don't want to use
7857 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7858 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7859 since this would make our programs incompatible with other
7860 Linux distributions. We also don't use something like
7861 <tt><var>arch</var>-unknown-linux</tt>, since the
7862 <tt>unknown</tt> does not look very good.
7867 <heading>Daemons</heading>
7870 The configuration files <file>/etc/services</file>,
7871 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7872 by the <prgn>netbase</prgn> package and must not be modified
7877 If a package requires a new entry in one of these files, the
7878 maintainer should get in contact with the
7879 <prgn>netbase</prgn> maintainer, who will add the entries
7880 and release a new version of the <prgn>netbase</prgn>
7885 The configuration file <file>/etc/inetd.conf</file> must not be
7886 modified by the package's scripts except via the
7887 <prgn>update-inetd</prgn> script or the
7888 <file>DebianNet.pm</file> Perl module. See their documentation
7889 for details on how to add entries.
7893 If a package wants to install an example entry into
7894 <file>/etc/inetd.conf</file>, the entry must be preceded with
7895 exactly one hash character (<tt>#</tt>). Such lines are
7896 treated as "commented out by user" by the
7897 <prgn>update-inetd</prgn> script and are not changed or
7898 activated during package updates.
7903 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7907 Some programs need to create pseudo-ttys. This should be done
7908 using Unix98 ptys if the C library supports it. The resulting
7909 program must not be installed setuid root, unless that
7910 is required for other functionality.
7914 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7915 <file>/var/log/lastlog</file> must be installed writable by
7916 group <tt>utmp</tt>. Programs which need to modify those
7917 files must be installed setgid <tt>utmp</tt>.
7922 <heading>Editors and pagers</heading>
7925 Some programs have the ability to launch an editor or pager
7926 program to edit or display a text document. Since there are
7927 lots of different editors and pagers available in the Debian
7928 distribution, the system administrator and each user should
7929 have the possibility to choose their preferred editor and
7934 In addition, every program should choose a good default
7935 editor/pager if none is selected by the user or system
7940 Thus, every program that launches an editor or pager must
7941 use the EDITOR or PAGER environment variable to determine
7942 the editor or pager the user wishes to use. If these
7943 variables are not set, the programs <file>/usr/bin/editor</file>
7944 and <file>/usr/bin/pager</file> should be used, respectively.
7948 These two files are managed through the <prgn>dpkg</prgn>
7949 "alternatives" mechanism. Thus every package providing an
7950 editor or pager must call the
7951 <prgn>update-alternatives</prgn> script to register these
7956 If it is very hard to adapt a program to make use of the
7957 EDITOR or PAGER variables, that program may be configured to
7958 use <file>/usr/bin/sensible-editor</file> and
7959 <file>/usr/bin/sensible-pager</file> as the editor or pager
7960 program respectively. These are two scripts provided in the
7961 <package>sensible-utils</package> package that check the EDITOR
7962 and PAGER variables and launch the appropriate program, and fall
7963 back to <file>/usr/bin/editor</file>
7964 and <file>/usr/bin/pager</file> if the variable is not set.
7968 A program may also use the VISUAL environment variable to
7969 determine the user's choice of editor. If it exists, it
7970 should take precedence over EDITOR. This is in fact what
7971 <file>/usr/bin/sensible-editor</file> does.
7975 It is not required for a package to depend on
7976 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7977 package to provide such virtual packages.<footnote>
7978 The Debian base system already provides an editor and a
7984 <sect id="web-appl">
7985 <heading>Web servers and applications</heading>
7988 This section describes the locations and URLs that should
7989 be used by all web servers and web applications in the
7996 Cgi-bin executable files are installed in the
7998 <example compact="compact">
7999 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8001 and should be referred to as
8002 <example compact="compact">
8003 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8009 <p>Access to HTML documents</p>
8012 HTML documents for a package are stored in
8013 <file>/usr/share/doc/<var>package</var></file>
8014 and can be referred to as
8015 <example compact="compact">
8016 http://localhost/doc/<var>package</var>/<var>filename</var>
8021 The web server should restrict access to the document
8022 tree so that only clients on the same host can read
8023 the documents. If the web server does not support such
8024 access controls, then it should not provide access at
8025 all, or ask about providing access during installation.
8030 <p>Access to images</p>
8032 It is recommended that images for a package be stored
8033 in <tt>/usr/share/images/<var>package</var></tt> and
8034 may be referred to through an alias <tt>/images/</tt>
8037 http://localhost/images/<package>/<filename>
8044 <p>Web Document Root</p>
8047 Web Applications should try to avoid storing files in
8048 the Web Document Root. Instead they should use the
8049 /usr/share/doc/<var>package</var> directory for
8050 documents and register the Web Application via the
8051 <package>doc-base</package> package. If access to the
8052 web document root is unavoidable then use
8053 <example compact="compact">
8056 as the Document Root. This might be just a symbolic
8057 link to the location where the system administrator
8058 has put the real document root.
8061 <item><p>Providing httpd and/or httpd-cgi</p>
8063 All web servers should provide the virtual package
8064 <tt>httpd</tt>. If a web server has CGI support it should
8065 provide <tt>httpd-cgi</tt> additionally.
8068 All web applications which do not contain CGI scripts should
8069 depend on <tt>httpd</tt>, all those web applications which
8070 <tt>do</tt> contain CGI scripts, should depend on
8078 <sect id="mail-transport-agents">
8079 <heading>Mail transport, delivery and user agents</heading>
8082 Debian packages which process electronic mail, whether mail
8083 user agents (MUAs) or mail transport agents (MTAs), must
8084 ensure that they are compatible with the configuration
8085 decisions below. Failure to do this may result in lost
8086 mail, broken <tt>From:</tt> lines, and other serious brain
8091 The mail spool is <file>/var/mail</file> and the interface to
8092 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8093 the FHS). On older systems, the mail spool may be
8094 physically located in <file>/var/spool/mail</file>, but all
8095 access to the mail spool should be via the
8096 <file>/var/mail</file> symlink. The mail spool is part of the
8097 base system and not part of the MTA package.
8101 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8102 programs (such as IMAP daemons) must lock the mailbox in an
8103 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8104 be combined with dot locking. To avoid deadlocks, a program
8105 should use <tt>fcntl()</tt> first and dot locking after
8106 this, or alternatively implement the two locking methods in
8107 a non blocking way<footnote>
8108 If it is not possible to establish both locks, the
8109 system shouldn't wait for the second lock to be
8110 established, but remove the first lock, wait a (random)
8111 time, and start over locking again.
8112 </footnote>. Using the functions <tt>maillock</tt> and
8113 <tt>mailunlock</tt> provided by the
8114 <tt>liblockfile*</tt><footnote>
8115 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8116 to use these functions.
8117 </footnote> packages is the recommended way to realize this.
8121 Mailboxes are generally either mode 600 and owned by
8122 <var>user</var> or mode 660 and owned by
8123 <tt><var>user</var>:mail</tt><footnote>
8124 There are two traditional permission schemes for mail spools:
8125 mode 600 with all mail delivery done by processes running as
8126 the destination user, or mode 660 and owned by group mail with
8127 mail delivery done by a process running as a system user in
8128 group mail. Historically, Debian required mode 660 mail
8129 spools to enable the latter model, but that model has become
8130 increasingly uncommon and the principle of least privilege
8131 indicates that mail systems that use the first model should
8132 use permissions of 600. If delivery to programs is permitted,
8133 it's easier to keep the mail system secure if the delivery
8134 agent runs as the destination user. Debian Policy therefore
8135 permits either scheme.
8136 </footnote>. The local system administrator may choose a
8137 different permission scheme; packages should not make
8138 assumptions about the permission and ownership of mailboxes
8139 unless required (such as when creating a new mailbox). A MUA
8140 may remove a mailbox (unless it has nonstandard permissions) in
8141 which case the MTA or another MUA must recreate it if needed.
8145 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8146 be setgid mail to do the locking mentioned above (and
8147 must obviously avoid accessing other users' mailboxes
8148 using this privilege).</p>
8151 <file>/etc/aliases</file> is the source file for the system mail
8152 aliases (e.g., postmaster, usenet, etc.), it is the one
8153 which the sysadmin and <prgn>postinst</prgn> scripts may
8154 edit. After <file>/etc/aliases</file> is edited the program or
8155 human editing it must call <prgn>newaliases</prgn>. All MTA
8156 packages must come with a <prgn>newaliases</prgn> program,
8157 even if it does nothing, but older MTA packages did not do
8158 this so programs should not fail if <prgn>newaliases</prgn>
8159 cannot be found. Note that because of this, all MTA
8160 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8161 <tt>Replaces: mail-transport-agent</tt> control file
8166 The convention of writing <tt>forward to
8167 <var>address</var></tt> in the mailbox itself is not
8168 supported. Use a <tt>.forward</tt> file instead.</p>
8171 The <prgn>rmail</prgn> program used by UUCP
8172 for incoming mail should be <file>/usr/sbin/rmail</file>.
8173 Likewise, <prgn>rsmtp</prgn>, for receiving
8174 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8178 If your package needs to know what hostname to use on (for
8179 example) outgoing news and mail messages which are generated
8180 locally, you should use the file <file>/etc/mailname</file>. It
8181 will contain the portion after the username and <tt>@</tt>
8182 (at) sign for email addresses of users on the machine
8183 (followed by a newline).
8187 Such a package should check for the existence of this file
8188 when it is being configured. If it exists, it should be
8189 used without comment, although an MTA's configuration script
8190 may wish to prompt the user even if it finds that this file
8191 exists. If the file does not exist, the package should
8192 prompt the user for the value (preferably using
8193 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8194 as well as using it in the package's configuration. The
8195 prompt should make it clear that the name will not just be
8196 used by that package. For example, in this situation the
8197 <tt>inn</tt> package could say something like:
8198 <example compact="compact">
8199 Please enter the "mail name" of your system. This is the
8200 hostname portion of the address to be shown on outgoing
8201 news and mail messages. The default is
8202 <var>syshostname</var>, your system's host name. Mail
8203 name ["<var>syshostname</var>"]:
8205 where <var>syshostname</var> is the output of <tt>hostname
8211 <heading>News system configuration</heading>
8214 All the configuration files related to the NNTP (news)
8215 servers and clients should be located under
8216 <file>/etc/news</file>.</p>
8219 There are some configuration issues that apply to a number
8220 of news clients and server packages on the machine. These
8224 <tag><file>/etc/news/organization</file></tag>
8226 A string which should appear as the
8227 organization header for all messages posted
8228 by NNTP clients on the machine
8231 <tag><file>/etc/news/server</file></tag>
8233 Contains the FQDN of the upstream NNTP
8234 server, or localhost if the local machine is
8239 Other global files may be added as required for cross-package news
8246 <heading>Programs for the X Window System</heading>
8249 <heading>Providing X support and package priorities</heading>
8252 Programs that can be configured with support for the X
8253 Window System must be configured to do so and must declare
8254 any package dependencies necessary to satisfy their
8255 runtime requirements when using the X Window System. If
8256 such a package is of higher priority than the X packages
8257 on which it depends, it is required that either the
8258 X-specific components be split into a separate package, or
8259 that an alternative version of the package, which includes
8260 X support, be provided, or that the package's priority be
8266 <heading>Packages providing an X server</heading>
8269 Packages that provide an X server that, directly or
8270 indirectly, communicates with real input and display
8271 hardware should declare in their control data that they
8272 provide the virtual package <tt>xserver</tt>.<footnote>
8273 This implements current practice, and provides an
8274 actual policy for usage of the <tt>xserver</tt>
8275 virtual package which appears in the virtual packages
8276 list. In a nutshell, X servers that interface
8277 directly with the display and input hardware or via
8278 another subsystem (e.g., GGI) should provide
8279 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8280 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8286 <heading>Packages providing a terminal emulator</heading>
8289 Packages that provide a terminal emulator for the X Window
8290 System which meet the criteria listed below should declare
8291 in their control data that they provide the virtual
8292 package <tt>x-terminal-emulator</tt>. They should also
8293 register themselves as an alternative for
8294 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8299 To be an <tt>x-terminal-emulator</tt>, a program must:
8300 <list compact="compact">
8302 Be able to emulate a DEC VT100 terminal, or a
8303 compatible terminal.
8307 Support the command-line option <tt>-e
8308 <var>command</var></tt>, which creates a new
8309 terminal window<footnote>
8310 "New terminal window" does not necessarily mean
8311 a new top-level X window directly parented by
8312 the window manager; it could, if the terminal
8313 emulator application were so coded, be a new
8314 "view" in a multiple-document interface (MDI).
8316 and runs the specified <var>command</var>,
8317 interpreting the entirety of the rest of the command
8318 line as a command to pass straight to exec, in the
8319 manner that <tt>xterm</tt> does.
8323 Support the command-line option <tt>-T
8324 <var>title</var></tt>, which creates a new terminal
8325 window with the window title <var>title</var>.
8332 <heading>Packages providing a window manager</heading>
8335 Packages that provide a window manager should declare in
8336 their control data that they provide the virtual package
8337 <tt>x-window-manager</tt>. They should also register
8338 themselves as an alternative for
8339 <file>/usr/bin/x-window-manager</file>, with a priority
8340 calculated as follows:
8341 <list compact="compact">
8343 Start with a priority of 20.
8347 If the window manager supports the Debian menu
8348 system, add 20 points if this support is available
8349 in the package's default configuration (i.e., no
8350 configuration files belonging to the system or user
8351 have to be edited to activate the feature); if
8352 configuration files must be modified, add only 10
8358 If the window manager complies with <url
8359 id="http://www.freedesktop.org/Standards/wm-spec"
8360 name="The Window Manager Specification Project">,
8361 written by the <url id="http://www.freedesktop.org/"
8362 name="Free Desktop Group">, add 40 points.
8366 If the window manager permits the X session to be
8367 restarted using a <em>different</em> window manager
8368 (without killing the X server) in its default
8369 configuration, add 10 points; otherwise add none.
8376 <heading>Packages providing fonts</heading>
8379 Packages that provide fonts for the X Window
8381 For the purposes of Debian Policy, a "font for the X
8382 Window System" is one which is accessed via X protocol
8383 requests. Fonts for the Linux console, for PostScript
8384 renderer, or any other purpose, do not fit this
8385 definition. Any tool which makes such fonts available
8386 to the X Window System, however, must abide by this
8389 must do a number of things to ensure that they are both
8390 available without modification of the X or font server
8391 configuration, and that they do not corrupt files used by
8392 other font packages to register information about
8396 Fonts of any type supported by the X Window System
8397 must be in a separate binary package from any
8398 executables, libraries, or documentation (except
8399 that specific to the fonts shipped, such as their
8400 license information). If one or more of the fonts
8401 so packaged are necessary for proper operation of
8402 the package with which they are associated the font
8403 package may be Recommended; if the fonts merely
8404 provide an enhancement, a Suggests relationship may
8405 be used. Packages must not Depend on font
8407 This is because the X server may retrieve fonts
8408 from the local file system or over the network
8409 from an X font server; the Debian package system
8410 is empowered to deal only with the local
8416 BDF fonts must be converted to PCF fonts with the
8417 <prgn>bdftopcf</prgn> utility (available in the
8418 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8419 placed in a directory that corresponds to their
8421 <list compact="compact">
8423 100 dpi fonts must be placed in
8424 <file>/usr/share/fonts/X11/100dpi/</file>.
8428 75 dpi fonts must be placed in
8429 <file>/usr/share/fonts/X11/75dpi/</file>.
8433 Character-cell fonts, cursor fonts, and other
8434 low-resolution fonts must be placed in
8435 <file>/usr/share/fonts/X11/misc/</file>.
8441 Type 1 fonts must be placed in
8442 <file>/usr/share/fonts/X11/Type1/</file>. If font
8443 metric files are available, they must be placed here
8448 Subdirectories of <file>/usr/share/fonts/X11/</file>
8449 other than those listed above must be neither
8450 created nor used. (The <file>PEX</file>, <file>CID</file>,
8451 <file>Speedo</file>, and <file>cyrillic</file> directories
8452 are excepted for historical reasons, but installation of
8453 files into these directories remains discouraged.)
8457 Font packages may, instead of placing files directly
8458 in the X font directories listed above, provide
8459 symbolic links in that font directory pointing to
8460 the files' actual location in the filesystem. Such
8461 a location must comply with the FHS.
8465 Font packages should not contain both 75dpi and
8466 100dpi versions of a font. If both are available,
8467 they should be provided in separate binary packages
8468 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8469 the names of the packages containing the
8470 corresponding fonts.
8474 Fonts destined for the <file>misc</file> subdirectory
8475 should not be included in the same package as 75dpi
8476 or 100dpi fonts; instead, they should be provided in
8477 a separate package with <tt>-misc</tt> appended to
8482 Font packages must not provide the files
8483 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8484 <file>fonts.scale</file> in a font directory:
8487 <file>fonts.dir</file> files must not be provided at all.
8491 <file>fonts.alias</file> and <file>fonts.scale</file>
8492 files, if needed, should be provided in the
8494 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8495 where <var>fontdir</var> is the name of the
8497 <file>/usr/share/fonts/X11/</file> where the
8498 package's corresponding fonts are stored
8499 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8500 <var>package</var> is the name of the package
8501 that provides these fonts, and
8502 <var>extension</var> is either <tt>scale</tt>
8503 or <tt>alias</tt>, whichever corresponds to
8510 Font packages must declare a dependency on
8511 <tt>xfonts-utils</tt> in their control
8516 Font packages that provide one or more
8517 <file>fonts.scale</file> files as described above must
8518 invoke <prgn>update-fonts-scale</prgn> on each
8519 directory into which they installed fonts
8520 <em>before</em> invoking
8521 <prgn>update-fonts-dir</prgn> on that directory.
8522 This invocation must occur in both the
8523 <prgn>postinst</prgn> (for all arguments) and
8524 <prgn>postrm</prgn> (for all arguments except
8525 <tt>upgrade</tt>) scripts.
8529 Font packages that provide one or more
8530 <file>fonts.alias</file> files as described above must
8531 invoke <prgn>update-fonts-alias</prgn> on each
8532 directory into which they installed fonts. This
8533 invocation must occur in both the
8534 <prgn>postinst</prgn> (for all arguments) and
8535 <prgn>postrm</prgn> (for all arguments except
8536 <tt>upgrade</tt>) scripts.
8540 Font packages must invoke
8541 <prgn>update-fonts-dir</prgn> on each directory into
8542 which they installed fonts. This invocation must
8543 occur in both the <prgn>postinst</prgn> (for all
8544 arguments) and <prgn>postrm</prgn> (for all
8545 arguments except <tt>upgrade</tt>) scripts.
8549 Font packages must not provide alias names for the
8550 fonts they include which collide with alias names
8551 already in use by fonts already packaged.
8555 Font packages must not provide fonts with the same
8556 XLFD registry name as another font already packaged.
8562 <sect1 id="appdefaults">
8563 <heading>Application defaults files</heading>
8566 Application defaults files must be installed in the
8567 directory <file>/etc/X11/app-defaults/</file> (use of a
8568 localized subdirectory of <file>/etc/X11/</file> as described
8569 in the <em>X Toolkit Intrinsics - C Language
8570 Interface</em> manual is also permitted). They must be
8571 registered as <tt>conffile</tt>s or handled as
8572 configuration files.
8576 Customization of programs' X resources may also be
8577 supported with the provision of a file with the same name
8578 as that of the package placed in the
8579 <file>/etc/X11/Xresources/</file> directory, which must
8580 registered as a <tt>conffile</tt> or handled as a
8581 configuration file.<footnote>
8582 Note that this mechanism is not the same as using
8583 app-defaults; app-defaults are tied to the client
8584 binary on the local file system, whereas X resources
8585 are stored in the X server and affect all connecting
8592 <heading>Installation directory issues</heading>
8595 Historically, packages using the X Window System used a
8596 separate set of installation directories from other packages.
8597 This practice has been discontinued and packages using the X
8598 Window System should now generally be installed in the same
8599 directories as any other package. Specifically, packages must
8600 not install files under the <file>/usr/X11R6/</file> directory
8601 and the <file>/usr/X11R6/</file> directory hierarchy should be
8602 regarded as obsolete.
8606 Include files previously installed under
8607 <file>/usr/X11R6/include/X11/</file> should be installed into
8608 <file>/usr/include/X11/</file>. For files previously
8609 installed into subdirectories of
8610 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8611 determine if subdirectories of <file>/usr/lib/</file> and
8612 <file>/usr/share/</file> can be used. If not, a subdirectory
8613 of <file>/usr/lib/X11/</file> should be used.
8617 Configuration files for window, display, or session managers
8618 or other applications that are tightly integrated with the X
8619 Window System may be placed in a subdirectory
8620 of <file>/etc/X11/</file> corresponding to the package name.
8621 Other X Window System applications should use
8622 the <file>/etc/</file> directory unless otherwise mandated by
8623 policy (such as for <ref id="appdefaults">).
8628 <heading>The OSF/Motif and OpenMotif libraries</heading>
8631 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8632 OpenMotif libraries</em><footnote>
8633 OSF/Motif and OpenMotif are collectively referred to as
8634 "Motif" in this policy document.
8636 should be compiled against and tested with LessTif (a free
8637 re-implementation of Motif) instead. If the maintainer
8638 judges that the program or programs do not work
8639 sufficiently well with LessTif to be distributed and
8640 supported, but do so when compiled against Motif, then two
8641 versions of the package should be created; one linked
8642 statically against Motif and with <tt>-smotif</tt>
8643 appended to the package name, and one linked dynamically
8644 against Motif and with <tt>-dmotif</tt> appended to the
8649 Both Motif-linked versions are dependent
8650 upon non-DFSG-compliant software and thus cannot be
8651 uploaded to the <em>main</em> distribution; if the
8652 software is itself DFSG-compliant it may be uploaded to
8653 the <em>contrib</em> distribution. While known existing
8654 versions of Motif permit unlimited redistribution of
8655 binaries linked against the library (whether statically or
8656 dynamically), it is the package maintainer's
8657 responsibility to determine whether this is permitted by
8658 the license of the copy of Motif in their possession.
8664 <heading>Perl programs and modules</heading>
8667 Perl programs and modules should follow the current Perl policy.
8671 The Perl policy can be found in the <tt>perl-policy</tt>
8672 files in the <tt>debian-policy</tt> package.
8673 It is also available from the Debian web mirrors at
8674 <tt><url name="/doc/packaging-manuals/perl-policy/"
8675 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8680 <heading>Emacs lisp programs</heading>
8683 Please refer to the "Debian Emacs Policy" for details of how to
8684 package emacs lisp programs.
8688 The Emacs policy is available in
8689 <file>debian-emacs-policy.gz</file> of the
8690 <package>emacsen-common</package> package.
8691 It is also available from the Debian web mirrors at
8692 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8693 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8698 <heading>Games</heading>
8701 The permissions on <file>/var/games</file> are mode 755, owner
8702 <tt>root</tt> and group <tt>root</tt>.
8706 Each game decides on its own security policy.</p>
8709 Games which require protected, privileged access to
8710 high-score files, saved games, etc., may be made
8711 set-<em>group</em>-id (mode 2755) and owned by
8712 <tt>root:games</tt>, and use files and directories with
8713 appropriate permissions (770 <tt>root:games</tt>, for
8714 example). They must not be made
8715 set-<em>user</em>-id, as this causes security problems. (If
8716 an attacker can subvert any set-user-id game they can
8717 overwrite the executable of any other, causing other players
8718 of these games to run a Trojan horse program. With a
8719 set-group-id game the attacker only gets access to less
8720 important game data, and if they can get at the other
8721 players' accounts at all it will take considerably more
8725 Some packages, for example some fortune cookie programs, are
8726 configured by the upstream authors to install with their
8727 data files or other static information made unreadable so
8728 that they can only be accessed through set-id programs
8729 provided. You should not do this in a Debian package: anyone can
8730 download the <file>.deb</file> file and read the data from it,
8731 so there is no point making the files unreadable. Not
8732 making the files unreadable also means that you don't have
8733 to make so many programs set-id, which reduces the risk of a
8737 As described in the FHS, binaries of games should be
8738 installed in the directory <file>/usr/games</file>. This also
8739 applies to games that use the X Window System. Manual pages
8740 for games (X and non-X games) should be installed in
8741 <file>/usr/share/man/man6</file>.</p>
8747 <heading>Documentation</heading>
8750 <heading>Manual pages</heading>
8753 You should install manual pages in <prgn>nroff</prgn> source
8754 form, in appropriate places under <file>/usr/share/man</file>.
8755 You should only use sections 1 to 9 (see the FHS for more
8756 details). You must not install a pre-formatted "cat page".
8760 Each program, utility, and function should have an
8761 associated manual page included in the same package. It is
8762 suggested that all configuration files also have a manual
8763 page included as well. Manual pages for protocols and other
8764 auxiliary things are optional.
8768 If no manual page is available, this is considered as a bug
8769 and should be reported to the Debian Bug Tracking System (the
8770 maintainer of the package is allowed to write this bug report
8771 themselves, if they so desire). Do not close the bug report
8772 until a proper man page is available.<footnote>
8773 It is not very hard to write a man page. See the
8774 <url id="http://www.schweikhardt.net/man_page_howto.html"
8775 name="Man-Page-HOWTO">,
8776 <manref name="man" section="7">, the examples
8777 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8778 the helper programs <prgn>help2man</prgn>, or the
8779 directory <file>/usr/share/doc/man-db/examples</file>.
8784 You may forward a complaint about a missing man page to the
8785 upstream authors, and mark the bug as forwarded in the
8786 Debian bug tracking system. Even though the GNU Project do
8787 not in general consider the lack of a man page to be a bug,
8788 we do; if they tell you that they don't consider it a bug
8789 you should leave the bug in our bug tracking system open
8794 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8798 If one man page needs to be accessible via several names it
8799 is better to use a symbolic link than the <file>.so</file>
8800 feature, but there is no need to fiddle with the relevant
8801 parts of the upstream source to change from <file>.so</file> to
8802 symlinks: don't do it unless it's easy. You should not
8803 create hard links in the manual page directories, nor put
8804 absolute filenames in <file>.so</file> directives. The filename
8805 in a <file>.so</file> in a man page should be relative to the
8806 base of the man page tree (usually
8807 <file>/usr/share/man</file>). If you do not create any links
8808 (whether symlinks, hard links, or <tt>.so</tt> directives)
8809 in the file system to the alternate names of the man page,
8810 then you should not rely on <prgn>man</prgn> finding your
8811 man page under those names based solely on the information in
8812 the man page's header.<footnote>
8813 Supporting this in <prgn>man</prgn> often requires
8814 unreasonable processing time to find a manual page or to
8815 report that none exists, and moves knowledge into man's
8816 database that would be better left in the file system.
8817 This support is therefore deprecated and will cease to
8818 be present in the future.
8823 Manual pages in locale-specific subdirectories of
8824 <file>/usr/share/man</file> should use either UTF-8 or the usual
8825 legacy encoding for that language (normally the one corresponding
8826 to the shortest relevant locale name in
8827 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8828 <file>/usr/share/man/fr</file> should use either UTF-8 or
8829 ISO-8859-1.<footnote>
8830 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8831 use. In future, all manual pages will be required to use
8837 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8838 included in the subdirectory name unless it indicates a
8839 significant difference in the language, as this excludes
8840 speakers of the language in other countries.<footnote>
8841 At the time of writing, Chinese and Portuguese are the main
8842 languages with such differences, so <file>pt_BR</file>,
8843 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8848 If a localized version of a manual page is provided, it should
8849 either be up-to-date or it should be obvious to the reader that
8850 it is outdated and the original manual page should be used
8851 instead. This can be done either by a note at the beginning of
8852 the manual page or by showing the missing or changed portions in
8853 the original language instead of the target language.
8858 <heading>Info documents</heading>
8861 Info documents should be installed in <file>/usr/share/info</file>.
8862 They should be compressed with <tt>gzip -9</tt>.
8866 The <prgn>install-info</prgn> program maintains a directory of
8867 installed info documents in <file>/usr/share/info/dir</file> for
8868 the use of info readers.<footnote>
8869 It was previously necessary for packages installing info
8870 documents to run <prgn>install-info</prgn> from maintainer
8871 scripts. This is no longer necessary. The installation
8872 system now uses dpkg triggers.
8874 This file must not be included in packages. Packages containing
8875 info documents should depend on <tt>dpkg (>= 1.15.4) |
8876 install-info</tt> to ensure that the directory file is properly
8877 rebuilt during partial upgrades from Debian 5.0 (lenny) and
8882 Info documents should contain section and directory entry
8883 information in the document for the use
8884 of <prgn>install-info</prgn>. The section should be specified
8885 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8886 space and the section of this info page. The directory entry or
8887 entries should be included between
8888 a <tt>START-INFO-DIR-ENTRY</tt> line and
8889 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8891 INFO-DIR-SECTION Individual utilities
8892 START-INFO-DIR-ENTRY
8893 * example: (example). An example info directory entry.
8896 To determine which section to use, you should look
8897 at <file>/usr/share/info/dir</file> on your system and choose
8898 the most relevant (or create a new section if none of the
8899 current sections are relevant).<footnote>
8900 Normally, info documents are generated from Texinfo source.
8901 To include this information in the generated info document, if
8902 it is absent, add commands like:
8904 @dircategory Individual utilities
8906 * example: (example). An example info directory entry.
8909 to the Texinfo source of the document and ensure that the info
8910 documents are rebuilt from source during the package build.
8916 <heading>Additional documentation</heading>
8919 Any additional documentation that comes with the package may
8920 be installed at the discretion of the package maintainer.
8921 Plain text documentation should be installed in the directory
8922 <file>/usr/share/doc/<var>package</var></file>, where
8923 <var>package</var> is the name of the package, and
8924 compressed with <tt>gzip -9</tt> unless it is small.
8928 If a package comes with large amounts of documentation which
8929 many users of the package will not require you should create
8930 a separate binary package to contain it, so that it does not
8931 take up disk space on the machines of users who do not need
8932 or want it installed.</p>
8935 It is often a good idea to put text information files
8936 (<file>README</file>s, changelogs, and so forth) that come with
8937 the source package in <file>/usr/share/doc/<var>package</var></file>
8938 in the binary package. However, you don't need to install
8939 the instructions for building and installing the package, of
8943 Packages must not require the existence of any files in
8944 <file>/usr/share/doc/</file> in order to function
8946 The system administrator should be able to
8947 delete files in <file>/usr/share/doc/</file> without causing
8948 any programs to break.
8950 Any files that are referenced by programs but are also
8951 useful as stand alone documentation should be installed under
8952 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8953 <file>/usr/share/doc/<var>package</var></file>.
8957 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8958 link to another directory in <file>/usr/share/doc</file> only if
8959 the two packages both come from the same source and the
8960 first package Depends on the second.<footnote>
8962 Please note that this does not override the section on
8963 changelog files below, so the file
8964 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8965 must refer to the changelog for the current version of
8966 <var>package</var> in question. In practice, this means
8967 that the sources of the target and the destination of the
8968 symlink must be the same (same source package and
8975 Former Debian releases placed all additional documentation
8976 in <file>/usr/doc/<var>package</var></file>. This has been
8977 changed to <file>/usr/share/doc/<var>package</var></file>,
8978 and packages must not put documentation in the directory
8979 <file>/usr/doc/<var>package</var></file>. <footnote>
8980 At this phase of the transition, we no longer require a
8981 symbolic link in <file>/usr/doc/</file>. At a later point,
8982 policy shall change to make the symbolic links a bug.
8988 <heading>Preferred documentation formats</heading>
8991 The unification of Debian documentation is being carried out
8995 If your package comes with extensive documentation in a
8996 markup format that can be converted to various other formats
8997 you should if possible ship HTML versions in a binary
8998 package, in the directory
8999 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9000 its subdirectories.<footnote>
9001 The rationale: The important thing here is that HTML
9002 docs should be available in <em>some</em> package, not
9003 necessarily in the main binary package.
9008 Other formats such as PostScript may be provided at the
9009 package maintainer's discretion.
9013 <sect id="copyrightfile">
9014 <heading>Copyright information</heading>
9017 Every package must be accompanied by a verbatim copy of its
9018 copyright and distribution license in the file
9019 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9020 file must neither be compressed nor be a symbolic link.
9024 In addition, the copyright file must say where the upstream
9025 sources (if any) were obtained. It should name the original
9026 authors of the package and the Debian maintainer(s) who were
9027 involved with its creation.
9031 Packages in the <em>contrib</em> or <em>non-free</em> archive
9032 areas should state in the copyright file that the package is not
9033 part of the Debian GNU/Linux distribution and briefly explain
9038 A copy of the file which will be installed in
9039 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9040 be in <file>debian/copyright</file> in the source package.
9044 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9045 link to another directory in <file>/usr/share/doc</file> only if
9046 the two packages both come from the same source and the
9047 first package Depends on the second. These rules are
9048 important because copyrights must be extractable by
9053 Packages distributed under the UCB BSD license, the Apache
9054 license (version 2.0), the Artistic license, the GNU GPL
9055 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9056 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9057 files under <file>/usr/share/common-licenses</file>,<footnote>
9060 <file>/usr/share/common-licenses/BSD</file>,
9061 <file>/usr/share/common-licenses/Apache-2.0</file>,
9062 <file>/usr/share/common-licenses/Artistic</file>,
9063 <file>/usr/share/common-licenses/GPL-2</file>,
9064 <file>/usr/share/common-licenses/GPL-3</file>,
9065 <file>/usr/share/common-licenses/LGPL-2</file>,
9066 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9067 <file>/usr/share/common-licenses/LGPL-3</file>,
9068 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9069 <file>/usr/share/common-licenses/GFDL-1.3</file>
9072 </footnote> rather than quoting them in the copyright
9077 You should not use the copyright file as a general <file>README</file>
9078 file. If your package has such a file it should be
9079 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9080 <file>README.Debian</file> or some other appropriate place.</p>
9084 <heading>Examples</heading>
9087 Any examples (configurations, source files, whatever),
9088 should be installed in a directory
9089 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9090 files should not be referenced by any program: they're there
9091 for the benefit of the system administrator and users as
9092 documentation only. Architecture-specific example files
9093 should be installed in a directory
9094 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9096 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9097 latter directory itself may be a symbolic link to the
9102 If the purpose of a package is to provide examples, then the
9103 example files may be installed into
9104 <file>/usr/share/doc/<var>package</var></file>.
9108 <sect id="changelogs">
9109 <heading>Changelog files</heading>
9112 Packages that are not Debian-native must contain a
9113 compressed copy of the <file>debian/changelog</file> file from
9114 the Debian source tree in
9115 <file>/usr/share/doc/<var>package</var></file> with the name
9116 <file>changelog.Debian.gz</file>.
9120 If an upstream changelog is available, it should be accessible as
9121 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9122 plain text. If the upstream changelog is distributed in
9123 HTML, it should be made available in that form as
9124 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9125 and a plain text <file>changelog.gz</file> should be generated
9126 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9127 the upstream changelog files do not already conform to this
9128 naming convention, then this may be achieved either by
9129 renaming the files, or by adding a symbolic link, at the
9130 maintainer's discretion.<footnote>
9131 Rationale: People should not have to look in places for
9132 upstream changelogs merely because they are given
9133 different names or are distributed in HTML format.
9138 All of these files should be installed compressed using
9139 <tt>gzip -9</tt>, as they will become large with time even
9140 if they start out small.
9144 If the package has only one changelog which is used both as
9145 the Debian changelog and the upstream one because there is
9146 no separate upstream maintainer then that changelog should
9147 usually be installed as
9148 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9149 there is a separate upstream maintainer, but no upstream
9150 changelog, then the Debian changelog should still be called
9151 <file>changelog.Debian.gz</file>.
9155 For details about the format and contents of the Debian
9156 changelog file, please see <ref id="dpkgchangelog">.
9161 <appendix id="pkg-scope">
9162 <heading>Introduction and scope of these appendices</heading>
9165 These appendices are taken essentially verbatim from the
9166 now-deprecated Packaging Manual, version 3.2.1.0. They are
9167 the chapters which are likely to be of use to package
9168 maintainers and which have not already been included in the
9169 policy document itself. Most of these sections are very likely
9170 not relevant to policy; they should be treated as
9171 documentation for the packaging system. Please note that these
9172 appendices are included for convenience, and for historical
9173 reasons: they used to be part of policy package, and they have
9174 not yet been incorporated into dpkg documentation. However,
9175 they still have value, and hence they are presented here.
9179 They have not yet been checked to ensure that they are
9180 compatible with the contents of policy, and if there are any
9181 contradictions, the version in the main policy document takes
9182 precedence. The remaining chapters of the old Packaging
9183 Manual have also not been read in detail to ensure that there
9184 are not parts which have been left out. Both of these will be
9189 Certain parts of the Packaging manual were integrated into the
9190 Policy Manual proper, and removed from the appendices. Links
9191 have been placed from the old locations to the new ones.
9195 <prgn>dpkg</prgn> is a suite of programs for creating binary
9196 package files and installing and removing them on Unix
9198 <prgn>dpkg</prgn> is targeted primarily at Debian
9199 GNU/Linux, but may work on or be ported to other
9205 The binary packages are designed for the management of
9206 installed executable programs (usually compiled binaries) and
9207 their associated data, though source code examples and
9208 documentation are provided as part of some packages.</p>
9211 This manual describes the technical aspects of creating Debian
9212 binary packages (<file>.deb</file> files). It documents the
9213 behavior of the package management programs
9214 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9215 they interact with packages.</p>
9218 It also documents the interaction between
9219 <prgn>dselect</prgn>'s core and the access method scripts it
9220 uses to actually install the selected packages, and describes
9221 how to create a new access method.</p>
9224 This manual does not go into detail about the options and
9225 usage of the package building and installation tools. It
9226 should therefore be read in conjunction with those programs'
9231 The utility programs which are provided with <prgn>dpkg</prgn>
9232 for managing various system configuration and similar issues,
9233 such as <prgn>update-rc.d</prgn> and
9234 <prgn>install-info</prgn>, are not described in detail here -
9235 please see their man pages.
9239 It is assumed that the reader is reasonably familiar with the
9240 <prgn>dpkg</prgn> System Administrators' manual.
9241 Unfortunately this manual does not yet exist.
9245 The Debian version of the FSF's GNU hello program is provided
9246 as an example for people wishing to create Debian
9247 packages. The Debian <prgn>debmake</prgn> package is
9248 recommended as a very helpful tool in creating and maintaining
9249 Debian packages. However, while the tools and examples are
9250 helpful, they do not replace the need to read and follow the
9251 Policy and Programmer's Manual.</p>
9254 <appendix id="pkg-binarypkg">
9255 <heading>Binary packages (from old Packaging Manual)</heading>
9258 The binary package has two main sections. The first part
9259 consists of various control information files and scripts used
9260 by <prgn>dpkg</prgn> when installing and removing. See <ref
9261 id="pkg-controlarea">.
9265 The second part is an archive containing the files and
9266 directories to be installed.
9270 In the future binary packages may also contain other
9271 components, such as checksums and digital signatures. The
9272 format for the archive is described in full in the
9273 <file>deb(5)</file> man page.
9277 <sect id="pkg-bincreating"><heading>Creating package files -
9278 <prgn>dpkg-deb</prgn>
9282 All manipulation of binary package files is done by
9283 <prgn>dpkg-deb</prgn>; it's the only program that has
9284 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9285 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9286 will spot that the options requested are appropriate to
9287 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9292 In order to create a binary package you must make a
9293 directory tree which contains all the files and directories
9294 you want to have in the file system data part of the package.
9295 In Debian-format source packages this directory is usually
9296 <file>debian/tmp</file>, relative to the top of the package's
9301 They should have the locations (relative to the root of the
9302 directory tree you're constructing) ownerships and
9303 permissions which you want them to have on the system when
9308 With current versions of <prgn>dpkg</prgn> the uid/username
9309 and gid/groupname mappings for the users and groups being
9310 used should be the same on the system where the package is
9311 built and the one where it is installed.
9315 You need to add one special directory to the root of the
9316 miniature file system tree you're creating:
9317 <prgn>DEBIAN</prgn>. It should contain the control
9318 information files, notably the binary package control file
9319 (see <ref id="pkg-controlfile">).
9323 The <prgn>DEBIAN</prgn> directory will not appear in the
9324 file system archive of the package, and so won't be installed
9325 by <prgn>dpkg</prgn> when the package is installed.
9329 When you've prepared the package, you should invoke:
9331 dpkg --build <var>directory</var>
9336 This will build the package in
9337 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9338 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9339 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9344 See the man page <manref name="dpkg-deb" section="8"> for details of how
9345 to examine the contents of this newly-created file. You may find the
9346 output of following commands enlightening:
9348 dpkg-deb --info <var>filename</var>.deb
9349 dpkg-deb --contents <var>filename</var>.deb
9350 dpkg --contents <var>filename</var>.deb
9352 To view the copyright file for a package you could use this command:
9354 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9359 <sect id="pkg-controlarea">
9360 <heading>Package control information files</heading>
9363 The control information portion of a binary package is a
9364 collection of files with names known to <prgn>dpkg</prgn>.
9365 It will treat the contents of these files specially - some
9366 of them contain information used by <prgn>dpkg</prgn> when
9367 installing or removing the package; others are scripts which
9368 the package maintainer wants <prgn>dpkg</prgn> to run.
9372 It is possible to put other files in the package control
9373 area, but this is not generally a good idea (though they
9374 will largely be ignored).
9378 Here is a brief list of the control info files supported by
9379 <prgn>dpkg</prgn> and a summary of what they're used for.
9384 <tag><tt>control</tt>
9387 This is the key description file used by
9388 <prgn>dpkg</prgn>. It specifies the package's name
9389 and version, gives its description for the user,
9390 states its relationships with other packages, and so
9391 forth. See <ref id="sourcecontrolfiles"> and
9392 <ref id="binarycontrolfiles">.
9396 It is usually generated automatically from information
9397 in the source package by the
9398 <prgn>dpkg-gencontrol</prgn> program, and with
9399 assistance from <prgn>dpkg-shlibdeps</prgn>.
9400 See <ref id="pkg-sourcetools">.
9404 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9409 These are executable files (usually scripts) which
9410 <prgn>dpkg</prgn> runs during installation, upgrade
9411 and removal of packages. They allow the package to
9412 deal with matters which are particular to that package
9413 or require more complicated processing than that
9414 provided by <prgn>dpkg</prgn>. Details of when and
9415 how they are called are in <ref id="maintainerscripts">.
9419 It is very important to make these scripts idempotent.
9420 See <ref id="idempotency">.
9424 The maintainer scripts are not guaranteed to run with a
9425 controlling terminal and may not be able to interact with
9426 the user. See <ref id="controllingterminal">.
9430 <tag><tt>conffiles</tt>
9433 This file contains a list of configuration files which
9434 are to be handled automatically by <prgn>dpkg</prgn>
9435 (see <ref id="pkg-conffiles">). Note that not necessarily
9436 every configuration file should be listed here.
9439 <tag><tt>shlibs</tt>
9442 This file contains a list of the shared libraries
9443 supplied by the package, with dependency details for
9444 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9445 when it determines what dependencies are required in a
9446 package control file. The <tt>shlibs</tt> file format
9447 is described on <ref id="shlibs">.
9452 <sect id="pkg-controlfile">
9453 <heading>The main control information file: <tt>control</tt></heading>
9456 The most important control information file used by
9457 <prgn>dpkg</prgn> when it installs a package is
9458 <tt>control</tt>. It contains all the package's "vital
9463 The binary package control files of packages built from
9464 Debian sources are made by a special tool,
9465 <prgn>dpkg-gencontrol</prgn>, which reads
9466 <file>debian/control</file> and <file>debian/changelog</file> to
9467 find the information it needs. See <ref id="pkg-sourcepkg"> for
9472 The fields in binary package control files are listed in
9473 <ref id="binarycontrolfiles">.
9477 A description of the syntax of control files and the purpose
9478 of the fields is available in <ref id="controlfields">.
9483 <heading>Time Stamps</heading>
9486 See <ref id="timestamps">.
9491 <appendix id="pkg-sourcepkg">
9492 <heading>Source packages (from old Packaging Manual) </heading>
9495 The Debian binary packages in the distribution are generated
9496 from Debian sources, which are in a special format to assist
9497 the easy and automatic building of binaries.
9500 <sect id="pkg-sourcetools">
9501 <heading>Tools for processing source packages</heading>
9504 Various tools are provided for manipulating source packages;
9505 they pack and unpack sources and help build of binary
9506 packages and help manage the distribution of new versions.
9510 They are introduced and typical uses described here; see
9511 <manref name="dpkg-source" section="1"> for full
9512 documentation about their arguments and operation.
9516 For examples of how to construct a Debian source package,
9517 and how to use those utilities that are used by Debian
9518 source packages, please see the <prgn>hello</prgn> example
9522 <sect1 id="pkg-dpkg-source">
9524 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9529 This program is frequently used by hand, and is also
9530 called from package-independent automated building scripts
9531 such as <prgn>dpkg-buildpackage</prgn>.
9535 To unpack a package it is typically invoked with
9537 dpkg-source -x <var>.../path/to/filename</var>.dsc
9542 with the <file><var>filename</var>.tar.gz</file> and
9543 <file><var>filename</var>.diff.gz</file> (if applicable) in
9544 the same directory. It unpacks into
9545 <file><var>package</var>-<var>version</var></file>, and if
9547 <file><var>package</var>-<var>version</var>.orig</file>, in
9548 the current directory.
9552 To create a packed source archive it is typically invoked:
9554 dpkg-source -b <var>package</var>-<var>version</var>
9559 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9560 <file>.diff.gz</file> (if appropriate) in the current
9561 directory. <prgn>dpkg-source</prgn> does not clean the
9562 source tree first - this must be done separately if it is
9567 See also <ref id="pkg-sourcearchives">.</p>
9571 <sect1 id="pkg-dpkg-buildpackage">
9573 <prgn>dpkg-buildpackage</prgn> - overall package-building
9578 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9579 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9580 targets <tt>clean</tt>, <tt>build</tt> and
9581 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9582 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9583 source and binary package upload.
9587 It is usually invoked by hand from the top level of the
9588 built or unbuilt source directory. It may be invoked with
9589 no arguments; useful arguments include:
9590 <taglist compact="compact">
9591 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9594 Do not sign the <tt>.changes</tt> file or the
9595 source package <tt>.dsc</tt> file, respectively.</p>
9597 <tag><tt>-p<var>sign-command</var></tt></tag>
9600 Invoke <var>sign-command</var> instead of finding
9601 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9602 <var>sign-command</var> must behave just like
9603 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9605 <tag><tt>-r<var>root-command</var></tt></tag>
9608 When root privilege is required, invoke the command
9609 <var>root-command</var>. <var>root-command</var>
9610 should invoke its first argument as a command, from
9611 the <prgn>PATH</prgn> if necessary, and pass its
9612 second and subsequent arguments to the command it
9613 calls. If no <var>root-command</var> is supplied
9614 then <var>dpkg-buildpackage</var> will take no
9615 special action to gain root privilege, so that for
9616 most packages it will have to be invoked as root to
9619 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9622 Two types of binary-only build and upload - see
9623 <manref name="dpkg-source" section="1">.
9630 <sect1 id="pkg-dpkg-gencontrol">
9632 <prgn>dpkg-gencontrol</prgn> - generates binary package
9637 This program is usually called from <file>debian/rules</file>
9638 (see <ref id="pkg-sourcetree">) in the top level of the source
9643 This is usually done just before the files and directories in the
9644 temporary directory tree where the package is being built have their
9645 permissions and ownerships set and the package is constructed using
9646 <prgn>dpkg-deb/</prgn>
9648 This is so that the control file which is produced has
9649 the right permissions
9654 <prgn>dpkg-gencontrol</prgn> must be called after all the
9655 files which are to go into the package have been placed in
9656 the temporary build directory, so that its calculation of
9657 the installed size of a package is correct.
9661 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9662 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9663 variable substitutions created by
9664 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9669 For a package which generates only one binary package, and
9670 which builds it in <file>debian/tmp</file> relative to the top
9671 of the source package, it is usually sufficient to call
9672 <prgn>dpkg-gencontrol</prgn>.
9676 Sources which build several binaries will typically need
9679 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9680 </example> The <tt>-P</tt> tells
9681 <prgn>dpkg-gencontrol</prgn> that the package is being
9682 built in a non-default directory, and the <tt>-p</tt>
9683 tells it which package's control file should be generated.
9687 <prgn>dpkg-gencontrol</prgn> also adds information to the
9688 list of files in <file>debian/files</file>, for the benefit of
9689 (for example) a future invocation of
9690 <prgn>dpkg-genchanges</prgn>.</p>
9693 <sect1 id="pkg-dpkg-shlibdeps">
9695 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9700 This program is usually called from <file>debian/rules</file>
9701 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9702 id="pkg-sourcetree">), in the top level of the source tree.
9706 Its arguments are executables and shared libraries
9709 They may be specified either in the locations in the
9710 source tree where they are created or in the locations
9711 in the temporary build tree where they are installed
9712 prior to binary package creation.
9714 </footnote> for which shared library dependencies should
9715 be included in the binary package's control file.
9719 If some of the found shared libraries should only
9720 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9721 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9722 by using the <tt>-d<var>dependency-field</var></tt> option
9723 before those executable(s). (Each <tt>-d</tt> option
9724 takes effect until the next <tt>-d</tt>.)
9728 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9729 output control file to be modified. Instead by default it
9730 adds to the <file>debian/substvars</file> file variable
9731 settings like <tt>shlibs:Depends</tt>. These variable
9732 settings must be referenced in dependency fields in the
9733 appropriate per-binary-package sections of the source
9738 For example, a package that generates an essential part
9739 which requires dependencies, and optional parts that
9740 which only require a recommendation, would separate those
9741 two sets of dependencies into two different fields.<footnote>
9742 At the time of writing, an example for this was the
9743 <package/xmms/ package, with Depends used for the xmms
9744 executable, Recommends for the plug-ins and Suggests for
9745 even more optional features provided by unzip.
9747 It can say in its <file>debian/rules</file>:
9749 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9750 -dRecommends <var>optionalpart anotheroptionalpart</var>
9752 and then in its main control file <file>debian/control</file>:
9755 Depends: ${shlibs:Depends}
9756 Recommends: ${shlibs:Recommends}
9762 Sources which produce several binary packages with
9763 different shared library dependency requirements can use
9764 the <tt>-p<var>varnameprefix</var></tt> option to override
9765 the default <tt>shlibs:</tt> prefix (one invocation of
9766 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9767 They can thus produce several sets of dependency
9768 variables, each of the form
9769 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9770 which can be referred to in the appropriate parts of the
9771 binary package control files.
9776 <sect1 id="pkg-dpkg-distaddfile">
9778 <prgn>dpkg-distaddfile</prgn> - adds a file to
9779 <file>debian/files</file>
9783 Some packages' uploads need to include files other than
9784 the source and binary package files.
9788 <prgn>dpkg-distaddfile</prgn> adds a file to the
9789 <file>debian/files</file> file so that it will be included in
9790 the <file>.changes</file> file when
9791 <prgn>dpkg-genchanges</prgn> is run.
9795 It is usually invoked from the <tt>binary</tt> target of
9796 <file>debian/rules</file>:
9798 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9800 The <var>filename</var> is relative to the directory where
9801 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9802 is usually the directory above the top level of the source
9803 tree. The <file>debian/rules</file> target should put the
9804 file there just before or just after calling
9805 <prgn>dpkg-distaddfile</prgn>.
9809 The <var>section</var> and <var>priority</var> are passed
9810 unchanged into the resulting <file>.changes</file> file.
9815 <sect1 id="pkg-dpkg-genchanges">
9817 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9822 This program is usually called by package-independent
9823 automatic building scripts such as
9824 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9829 It is usually called in the top level of a built source
9830 tree, and when invoked with no arguments will print out a
9831 straightforward <file>.changes</file> file based on the
9832 information in the source package's changelog and control
9833 file and the binary and source packages which should have
9839 <sect1 id="pkg-dpkg-parsechangelog">
9841 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9842 representation of a changelog
9846 This program is used internally by
9847 <prgn>dpkg-source</prgn> et al. It may also occasionally
9848 be useful in <file>debian/rules</file> and elsewhere. It
9849 parses a changelog, <file>debian/changelog</file> by default,
9850 and prints a control-file format representation of the
9851 information in it to standard output.
9855 <sect1 id="pkg-dpkg-architecture">
9857 <prgn>dpkg-architecture</prgn> - information about the build and
9862 This program can be used manually, but is also invoked by
9863 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9864 environment or make variables which specify the build and host
9865 architecture for the package building process.
9870 <sect id="pkg-sourcetree">
9871 <heading>The Debianised source tree</heading>
9874 The source archive scheme described later is intended to
9875 allow a Debianised source tree with some associated control
9876 information to be reproduced and transported easily. The
9877 Debianised source tree is a version of the original program
9878 with certain files added for the benefit of the
9879 Debianisation process, and with any other changes required
9880 made to the rest of the source code and installation
9885 The extra files created for Debian are in the subdirectory
9886 <file>debian</file> of the top level of the Debianised source
9887 tree. They are described below.
9890 <sect1 id="pkg-debianrules">
9891 <heading><file>debian/rules</file> - the main building script</heading>
9894 See <ref id="debianrules">.
9899 <sect1 id="pkg-dpkgchangelog">
9900 <heading><file>debian/changelog</file></heading>
9903 See <ref id="dpkgchangelog">.
9906 <sect2><heading>Defining alternative changelog formats
9910 It is possible to use a different format to the standard
9911 one, by providing a parser for the format you wish to
9916 In order to have <tt>dpkg-parsechangelog</tt> run your
9917 parser, you must include a line within the last 40 lines
9918 of your file matching the Perl regular expression:
9919 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9920 parentheses should be the name of the format. For
9921 example, you might say:
9923 @@@ changelog-format: joebloggs @@@
9925 Changelog format names are non-empty strings of alphanumerics.
9929 If such a line exists then <tt>dpkg-parsechangelog</tt>
9930 will look for the parser as
9931 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9933 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9934 it is an error for it not to find it, or for it not to
9935 be an executable program. The default changelog format
9936 is <tt>dpkg</tt>, and a parser for it is provided with
9937 the <tt>dpkg</tt> package.
9941 The parser will be invoked with the changelog open on
9942 standard input at the start of the file. It should read
9943 the file (it may seek if it wishes) to determine the
9944 information required and return the parsed information
9945 to standard output in the form of a series of control
9946 fields in the standard format. By default it should
9947 return information about only the most recent version in
9948 the changelog; it should accept a
9949 <tt>-v<var>version</var></tt> option to return changes
9950 information from all versions present <em>strictly
9951 after</em> <var>version</var>, and it should then be an
9952 error for <var>version</var> not to be present in the
9958 <list compact="compact">
9959 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9960 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9961 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9962 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9963 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9964 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9965 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9970 If several versions are being returned (due to the use
9971 of <tt>-v</tt>), the urgency value should be of the
9972 highest urgency code listed at the start of any of the
9973 versions requested followed by the concatenated
9974 (space-separated) comments from all the versions
9975 requested; the maintainer, version, distribution and
9976 date should always be from the most recent version.
9980 For the format of the <tt>Changes</tt> field see
9981 <ref id="f-Changes">.
9985 If the changelog format which is being parsed always or
9986 almost always leaves a blank line between individual
9987 change notes these blank lines should be stripped out,
9988 so as to make the resulting output compact.
9992 If the changelog format does not contain date or package
9993 name information this information should be omitted from
9994 the output. The parser should not attempt to synthesize
9995 it or find it from other sources.
9999 If the changelog does not have the expected format the
10000 parser should exit with a nonzero exit status, rather
10001 than trying to muddle through and possibly generating
10006 A changelog parser may not interact with the user at
10012 <sect1 id="pkg-srcsubstvars">
10013 <heading><file>debian/substvars</file> and variable substitutions</heading>
10016 See <ref id="substvars">.
10022 <heading><file>debian/files</file></heading>
10025 See <ref id="debianfiles">.
10029 <sect1><heading><file>debian/tmp</file>
10033 This is the canonical temporary location for the
10034 construction of binary packages by the <tt>binary</tt>
10035 target. The directory <file>tmp</file> serves as the root of
10036 the file system tree as it is being constructed (for
10037 example, by using the package's upstream makefiles install
10038 targets and redirecting the output there), and it also
10039 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10040 id="pkg-bincreating">.
10044 If several binary packages are generated from the same
10045 source tree it is usual to use several
10046 <file>debian/tmp<var>something</var></file> directories, for
10047 example <file>tmp-a</file> or <file>tmp-doc</file>.
10051 Whatever <file>tmp</file> directories are created and used by
10052 <tt>binary</tt> must of course be removed by the
10053 <tt>clean</tt> target.</p></sect1>
10057 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10061 As it exists on the FTP site, a Debian source package
10062 consists of three related files. You must have the right
10063 versions of all three to be able to use them.
10068 <tag>Debian source control file - <tt>.dsc</tt></tag>
10070 This file is a control file used by <prgn>dpkg-source</prgn>
10071 to extract a source package.
10072 See <ref id="debiansourcecontrolfiles">.
10076 Original source archive -
10078 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10084 This is a compressed (with <tt>gzip -9</tt>)
10085 <prgn>tar</prgn> file containing the source code from
10086 the upstream authors of the program.
10091 Debianisation diff -
10093 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10099 This is a unified context diff (<tt>diff -u</tt>)
10100 giving the changes which are required to turn the
10101 original source into the Debian source. These changes
10102 may only include editing and creating plain files.
10103 The permissions of files, the targets of symbolic
10104 links and the characteristics of special files or
10105 pipes may not be changed and no files may be removed
10110 All the directories in the diff must exist, except the
10111 <file>debian</file> subdirectory of the top of the source
10112 tree, which will be created by
10113 <prgn>dpkg-source</prgn> if necessary when unpacking.
10117 The <prgn>dpkg-source</prgn> program will
10118 automatically make the <file>debian/rules</file> file
10119 executable (see below).</p></item>
10124 If there is no original source code - for example, if the
10125 package is specially prepared for Debian or the Debian
10126 maintainer is the same as the upstream maintainer - the
10127 format is slightly different: then there is no diff, and the
10129 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10130 and preferably contains a directory named
10131 <file><var>package</var>-<var>version</var></file>.
10136 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10139 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10140 Debian source package. However, if it is not available it
10141 is possible to unpack a Debian source archive as follows:
10142 <enumlist compact="compact">
10145 Untar the tarfile, which will create a <file>.orig</file>
10149 <p>Rename the <file>.orig</file> directory to
10150 <file><var>package</var>-<var>version</var></file>.</p>
10154 Create the subdirectory <file>debian</file> at the top of
10155 the source tree.</p>
10157 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10159 <item><p>Untar the tarfile again if you want a copy of the original
10160 source code alongside the Debianised version.</p>
10165 It is not possible to generate a valid Debian source archive
10166 without using <prgn>dpkg-source</prgn>. In particular,
10167 attempting to use <prgn>diff</prgn> directly to generate the
10168 <file>.diff.gz</file> file will not work.
10172 <heading>Restrictions on objects in source packages</heading>
10175 The source package may not contain any hard links
10177 This is not currently detected when building source
10178 packages, but only when extracting
10182 Hard links may be permitted at some point in the
10183 future, but would require a fair amount of
10185 </footnote>, device special files, sockets or setuid or
10188 Setgid directories are allowed.
10193 The source packaging tools manage the changes between the
10194 original and Debianised source using <prgn>diff</prgn> and
10195 <prgn>patch</prgn>. Turning the original source tree as
10196 included in the <file>.orig.tar.gz</file> into the debianised
10197 source must not involve any changes which cannot be
10198 handled by these tools. Problematic changes which cause
10199 <prgn>dpkg-source</prgn> to halt with an error when
10200 building the source package are:
10201 <list compact="compact">
10202 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10204 <item><p>Changing the targets of symbolic links.</p>
10206 <item><p>Creating directories, other than <file>debian</file>.</p>
10208 <item><p>Changes to the contents of binary files.</p></item>
10209 </list> Changes which cause <prgn>dpkg-source</prgn> to
10210 print a warning but continue anyway are:
10211 <list compact="compact">
10214 Removing files, directories or symlinks.
10216 Renaming a file is not treated specially - it is
10217 seen as the removal of the old file (which
10218 generates a warning, but is otherwise ignored),
10219 and the creation of the new one.
10225 Changed text files which are missing the usual final
10226 newline (either in the original or the modified
10231 Changes which are not represented, but which are not detected by
10232 <prgn>dpkg-source</prgn>, are:
10233 <list compact="compact">
10234 <item><p>Changing the permissions of files (other than
10235 <file>debian/rules</file>) and directories.</p></item>
10240 The <file>debian</file> directory and <file>debian/rules</file>
10241 are handled specially by <prgn>dpkg-source</prgn> - before
10242 applying the changes it will create the <file>debian</file>
10243 directory, and afterwards it will make
10244 <file>debian/rules</file> world-executable.
10250 <appendix id="pkg-controlfields">
10251 <heading>Control files and their fields (from old Packaging Manual)</heading>
10254 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10255 data in a common format, known as control files. Binary and
10256 source packages have control data as do the <file>.changes</file>
10257 files which control the installation of uploaded files, and
10258 <prgn>dpkg</prgn>'s internal databases are in a similar
10263 <heading>Syntax of control files</heading>
10266 See <ref id="controlsyntax">.
10270 It is important to note that there are several fields which
10271 are optional as far as <prgn>dpkg</prgn> and the related
10272 tools are concerned, but which must appear in every Debian
10273 package, or whose omission may cause problems.
10278 <heading>List of fields</heading>
10281 See <ref id="controlfieldslist">.
10285 This section now contains only the fields that didn't belong
10286 to the Policy manual.
10289 <sect1 id="pkg-f-Filename">
10290 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10293 These fields in <tt>Packages</tt> files give the
10294 filename(s) of (the parts of) a package in the
10295 distribution directories, relative to the root of the
10296 Debian hierarchy. If the package has been split into
10297 several parts the parts are all listed in order, separated
10302 <sect1 id="pkg-f-Size">
10303 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10306 These fields in <file>Packages</file> files give the size (in
10307 bytes, expressed in decimal) and MD5 checksum of the
10308 file(s) which make(s) up a binary package in the
10309 distribution. If the package is split into several parts
10310 the values for the parts are listed in order, separated by
10315 <sect1 id="pkg-f-Status">
10316 <heading><tt>Status</tt></heading>
10319 This field in <prgn>dpkg</prgn>'s status file records
10320 whether the user wants a package installed, removed or
10321 left alone, whether it is broken (requiring
10322 re-installation) or not and what its current state on the
10323 system is. Each of these pieces of information is a
10328 <sect1 id="pkg-f-Config-Version">
10329 <heading><tt>Config-Version</tt></heading>
10332 If a package is not installed or not configured, this
10333 field in <prgn>dpkg</prgn>'s status file records the last
10334 version of the package which was successfully
10339 <sect1 id="pkg-f-Conffiles">
10340 <heading><tt>Conffiles</tt></heading>
10343 This field in <prgn>dpkg</prgn>'s status file contains
10344 information about the automatically-managed configuration
10345 files held by a package. This field should <em>not</em>
10346 appear anywhere in a package!
10351 <heading>Obsolete fields</heading>
10354 These are still recognized by <prgn>dpkg</prgn> but should
10355 not appear anywhere any more.
10357 <taglist compact="compact">
10359 <tag><tt>Revision</tt></tag>
10360 <tag><tt>Package-Revision</tt></tag>
10361 <tag><tt>Package_Revision</tt></tag>
10363 The Debian revision part of the package version was
10364 at one point in a separate control file field. This
10365 field went through several names.
10368 <tag><tt>Recommended</tt></tag>
10369 <item>Old name for <tt>Recommends</tt>.</item>
10371 <tag><tt>Optional</tt></tag>
10372 <item>Old name for <tt>Suggests</tt>.</item>
10374 <tag><tt>Class</tt></tag>
10375 <item>Old name for <tt>Priority</tt>.</item>
10384 <appendix id="pkg-conffiles">
10385 <heading>Configuration file handling (from old Packaging Manual)</heading>
10388 <prgn>dpkg</prgn> can do a certain amount of automatic
10389 handling of package configuration files.
10393 Whether this mechanism is appropriate depends on a number of
10394 factors, but basically there are two approaches to any
10395 particular configuration file.
10399 The easy method is to ship a best-effort configuration in the
10400 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10401 handle updates. If the user is unlikely to want to edit the
10402 file, but you need them to be able to without losing their
10403 changes, and a new package with a changed version of the file
10404 is only released infrequently, this is a good approach.
10408 The hard method is to build the configuration file from
10409 scratch in the <prgn>postinst</prgn> script, and to take the
10410 responsibility for fixing any mistakes made in earlier
10411 versions of the package automatically. This will be
10412 appropriate if the file is likely to need to be different on
10416 <sect><heading>Automatic handling of configuration files by
10421 A package may contain a control area file called
10422 <tt>conffiles</tt>. This file should be a list of filenames
10423 of configuration files needing automatic handling, separated
10424 by newlines. The filenames should be absolute pathnames,
10425 and the files referred to should actually exist in the
10430 When a package is upgraded <prgn>dpkg</prgn> will process
10431 the configuration files during the configuration stage,
10432 shortly before it runs the package's <prgn>postinst</prgn>
10437 For each file it checks to see whether the version of the
10438 file included in the package is the same as the one that was
10439 included in the last version of the package (the one that is
10440 being upgraded from); it also compares the version currently
10441 installed on the system with the one shipped with the last
10446 If neither the user nor the package maintainer has changed
10447 the file, it is left alone. If one or the other has changed
10448 their version, then the changed version is preferred - i.e.,
10449 if the user edits their file, but the package maintainer
10450 doesn't ship a different version, the user's changes will
10451 stay, silently, but if the maintainer ships a new version
10452 and the user hasn't edited it the new version will be
10453 installed (with an informative message). If both have
10454 changed their version the user is prompted about the problem
10455 and must resolve the differences themselves.
10459 The comparisons are done by calculating the MD5 message
10460 digests of the files, and storing the MD5 of the file as it
10461 was included in the most recent version of the package.
10465 When a package is installed for the first time
10466 <prgn>dpkg</prgn> will install the file that comes with it,
10467 unless that would mean overwriting a file already on the
10472 However, note that <prgn>dpkg</prgn> will <em>not</em>
10473 replace a conffile that was removed by the user (or by a
10474 script). This is necessary because with some programs a
10475 missing file produces an effect hard or impossible to
10476 achieve in another way, so that a missing file needs to be
10477 kept that way if the user did it.
10481 Note that a package should <em>not</em> modify a
10482 <prgn>dpkg</prgn>-handled conffile in its maintainer
10483 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10484 the user confusing and possibly dangerous options for
10485 conffile update when the package is upgraded.</p>
10488 <sect><heading>Fully-featured maintainer script configuration
10493 For files which contain site-specific information such as
10494 the hostname and networking details and so forth, it is
10495 better to create the file in the package's
10496 <prgn>postinst</prgn> script.
10500 This will typically involve examining the state of the rest
10501 of the system to determine values and other information, and
10502 may involve prompting the user for some information which
10503 can't be obtained some other way.
10507 When using this method there are a couple of important
10508 issues which should be considered:
10512 If you discover a bug in the program which generates the
10513 configuration file, or if the format of the file changes
10514 from one version to the next, you will have to arrange for
10515 the postinst script to do something sensible - usually this
10516 will mean editing the installed configuration file to remove
10517 the problem or change the syntax. You will have to do this
10518 very carefully, since the user may have changed the file,
10519 perhaps to fix the very problem that your script is trying
10520 to deal with - you will have to detect these situations and
10521 deal with them correctly.
10525 If you do go down this route it's probably a good idea to
10526 make the program that generates the configuration file(s) a
10527 separate program in <file>/usr/sbin</file>, by convention called
10528 <file><var>package</var>config</file> and then run that if
10529 appropriate from the post-installation script. The
10530 <tt><var>package</var>config</tt> program should not
10531 unquestioningly overwrite an existing configuration - if its
10532 mode of operation is geared towards setting up a package for
10533 the first time (rather than any arbitrary reconfiguration
10534 later) you should have it check whether the configuration
10535 already exists, and require a <tt>--force</tt> flag to
10536 overwrite it.</p></sect>
10539 <appendix id="pkg-alternatives"><heading>Alternative versions of
10540 an interface - <prgn>update-alternatives</prgn> (from old
10545 When several packages all provide different versions of the
10546 same program or file it is useful to have the system select a
10547 default, but to allow the system administrator to change it
10548 and have their decisions respected.
10552 For example, there are several versions of the <prgn>vi</prgn>
10553 editor, and there is no reason to prevent all of them from
10554 being installed at once, each under their own name
10555 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10556 Nevertheless it is desirable to have the name <tt>vi</tt>
10557 refer to something, at least by default.
10561 If all the packages involved cooperate, this can be done with
10562 <prgn>update-alternatives</prgn>.
10566 Each package provides its own version under its own name, and
10567 calls <prgn>update-alternatives</prgn> in its postinst to
10568 register its version (and again in its prerm to deregister
10573 See the man page <manref name="update-alternatives"
10574 section="8"> for details.
10578 If <prgn>update-alternatives</prgn> does not seem appropriate
10579 you may wish to consider using diversions instead.</p>
10582 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10583 package's version of a file (from old Packaging Manual)
10587 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10588 when it reinstalls the package it belongs to, and to have it
10589 put the file from the package somewhere else instead.
10593 This can be used locally to override a package's version of a
10594 file, or by one package to override another's version (or
10595 provide a wrapper for it).
10599 Before deciding to use a diversion, read <ref
10600 id="pkg-alternatives"> to see if you really want a diversion
10601 rather than several alternative versions of a program.
10605 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10606 and updated by a special program <prgn>dpkg-divert</prgn>.
10607 Please see <manref name="dpkg-divert" section="8"> for full
10608 details of its operation.
10612 When a package wishes to divert a file from another, it should
10613 call <prgn>dpkg-divert</prgn> in its preinst to add the
10614 diversion and rename the existing file. For example,
10615 supposing that a <prgn>smailwrapper</prgn> package wishes to
10616 install a wrapper around <file>/usr/sbin/smail</file>:
10618 dpkg-divert --package smailwrapper --add --rename \
10619 --divert /usr/sbin/smail.real /usr/sbin/smail
10620 </example> The <tt>--package smailwrapper</tt> ensures that
10621 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10622 can bypass the diversion and get installed as the true version.
10623 It's safe to add the diversion unconditionally on upgrades since
10624 it will be left unchanged if it already exists, but
10625 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10626 message, make the command conditional on the version from which
10627 the package is being upgraded:
10629 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10630 dpkg-divert --package smailwrapper --add --rename \
10631 --divert /usr/sbin/smail.real /usr/sbin/smail
10633 </example> where <tt>1.0-2</tt> is the version at which the
10634 diversion was first added to the package. Running the command
10635 during abort-upgrade is pointless but harmless.
10639 The postrm has to do the reverse:
10641 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10642 dpkg-divert --package smailwrapper --remove --rename \
10643 --divert /usr/sbin/smail.real /usr/sbin/smail
10645 </example> If the diversion was added at a particular version, the
10646 postrm should also handle the failure case of upgrading from an
10647 older version (unless the older version is so old that direct
10648 upgrades are no longer supported):
10650 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10651 dpkg-divert --package smailwrapper --remove --rename \
10652 --divert /usr/sbin/smail.real /usr/sbin/smail
10654 </example> where <tt>1.02-2</tt> is the version at which the
10655 diversion was first added to the package. The postrm should not
10656 remove the diversion on upgrades both because there's no reason to
10657 remove the diversion only to immediately re-add it and since the
10658 postrm of the old package is run after unpacking so the removal of
10659 the diversion will fail.
10663 Do not attempt to divert a file which is vitally important for
10664 the system's operation - when using <prgn>dpkg-divert</prgn>
10665 there is a time, after it has been diverted but before
10666 <prgn>dpkg</prgn> has installed the new version, when the file
10667 does not exist.</p>
10672 <!-- Local variables: -->
10673 <!-- indent-tabs-mode: t -->
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