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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 unpacked
1051 <em>and</em> configured before it can be unpacked. 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 unpacked, 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 The maintainer scripts are guaranteed to run with a
3551 controlling terminal and can interact with the user.
3552 Because these scripts may be executed with standard output
3553 redirected into a pipe for logging purposes, Perl scripts
3554 should set unbuffered output by setting <tt>$|=1</tt> so
3555 that the output is printed immediately rather than being
3559 <sect id="exitstatus">
3560 <heading>Exit status</heading>
3563 Each script must return a zero exit status for
3564 success, or a nonzero one for failure, since the package
3565 management system looks for the exit status of these scripts
3566 and determines what action to take next based on that datum.
3570 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3575 <list compact="compact">
3577 <var>new-preinst</var> <tt>install</tt>
3580 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3583 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3586 <var>old-preinst</var> <tt>abort-upgrade</tt>
3587 <var>new-version</var>
3592 <list compact="compact">
3594 <var>postinst</var> <tt>configure</tt>
3595 <var>most-recently-configured-version</var>
3598 <var>old-postinst</var> <tt>abort-upgrade</tt>
3599 <var>new-version</var>
3602 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3603 <tt>in-favour</tt> <var>package</var>
3604 <var>new-version</var>
3607 <var>postinst</var> <tt>abort-remove</tt>
3610 <var>deconfigured's-postinst</var>
3611 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3612 <var>failed-install-package</var> <var>version</var>
3613 [<tt>removing</tt> <var>conflicting-package</var>
3619 <list compact="compact">
3621 <var>prerm</var> <tt>remove</tt>
3624 <var>old-prerm</var> <tt>upgrade</tt>
3625 <var>new-version</var>
3628 <var>new-prerm</var> <tt>failed-upgrade</tt>
3629 <var>old-version</var>
3632 <var>conflictor's-prerm</var> <tt>remove</tt>
3633 <tt>in-favour</tt> <var>package</var>
3634 <var>new-version</var>
3637 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3638 <tt>in-favour</tt> <var>package-being-installed</var>
3639 <var>version</var> [<tt>removing</tt>
3640 <var>conflicting-package</var>
3646 <list compact="compact">
3648 <var>postrm</var> <tt>remove</tt>
3651 <var>postrm</var> <tt>purge</tt>
3654 <var>old-postrm</var> <tt>upgrade</tt>
3655 <var>new-version</var>
3658 <var>new-postrm</var> <tt>failed-upgrade</tt>
3659 <var>old-version</var>
3662 <var>new-postrm</var> <tt>abort-install</tt>
3665 <var>new-postrm</var> <tt>abort-install</tt>
3666 <var>old-version</var>
3669 <var>new-postrm</var> <tt>abort-upgrade</tt>
3670 <var>old-version</var>
3673 <var>disappearer's-postrm</var> <tt>disappear</tt>
3674 <var>overwriter</var>
3675 <var>overwriter-version</var>
3681 <sect id="unpackphase">
3682 <heading>Details of unpack phase of installation or upgrade</heading>
3685 The procedure on installation/upgrade/overwrite/disappear
3686 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3687 stage of <tt>dpkg --install</tt>) is as follows. In each
3688 case, if a major error occurs (unless listed below) the
3689 actions are, in general, run backwards - this means that the
3690 maintainer scripts are run with different arguments in
3691 reverse order. These are the "error unwind" calls listed
3698 If a version of the package is already installed, call
3699 <example compact="compact">
3700 <var>old-prerm</var> upgrade <var>new-version</var>
3704 If the script runs but exits with a non-zero
3705 exit status, <prgn>dpkg</prgn> will attempt:
3706 <example compact="compact">
3707 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3709 If this works, the upgrade continues. If this
3710 does not work, the error unwind:
3711 <example compact="compact">
3712 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3714 If this works, then the old-version is
3715 "Installed", if not, the old version is in a
3716 "Failed-Config" state.
3722 If a "conflicting" package is being removed at the same time,
3723 or if any package will be broken (due to <tt>Breaks</tt>):
3726 If <tt>--auto-deconfigure</tt> is
3727 specified, call, for each package to be deconfigured
3728 due to <tt>Breaks</tt>:
3729 <example compact="compact">
3730 <var>deconfigured's-prerm</var> deconfigure \
3731 in-favour <var>package-being-installed</var> <var>version</var>
3734 <example compact="compact">
3735 <var>deconfigured's-postinst</var> abort-deconfigure \
3736 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3738 The deconfigured packages are marked as
3739 requiring configuration, so that if
3740 <tt>--install</tt> is used they will be
3741 configured again if possible.
3744 If any packages depended on a conflicting
3745 package being removed and <tt>--auto-deconfigure</tt> is
3746 specified, call, for each such package:
3747 <example compact="compact">
3748 <var>deconfigured's-prerm</var> deconfigure \
3749 in-favour <var>package-being-installed</var> <var>version</var> \
3750 removing <var>conflicting-package</var> <var>version</var>
3753 <example compact="compact">
3754 <var>deconfigured's-postinst</var> abort-deconfigure \
3755 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3756 removing <var>conflicting-package</var> <var>version</var>
3758 The deconfigured packages are marked as
3759 requiring configuration, so that if
3760 <tt>--install</tt> is used they will be
3761 configured again if possible.
3764 To prepare for removal of each conflicting package, call:
3765 <example compact="compact">
3766 <var>conflictor's-prerm</var> remove \
3767 in-favour <var>package</var> <var>new-version</var>
3770 <example compact="compact">
3771 <var>conflictor's-postinst</var> abort-remove \
3772 in-favour <var>package</var> <var>new-version</var>
3781 If the package is being upgraded, call:
3782 <example compact="compact">
3783 <var>new-preinst</var> upgrade <var>old-version</var>
3785 If this fails, we call:
3787 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3794 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3796 is called. If this works, then the old version
3797 is in an "Installed" state, or else it is left
3798 in an "Unpacked" state.
3803 If it fails, then the old version is left
3804 in an "Half-Installed" state.
3811 Otherwise, if the package had some configuration
3812 files from a previous version installed (i.e., it
3813 is in the "configuration files only" state):
3814 <example compact="compact">
3815 <var>new-preinst</var> install <var>old-version</var>
3819 <var>new-postrm</var> abort-install <var>old-version</var>
3821 If this fails, the package is left in a
3822 "Half-Installed" state, which requires a
3823 reinstall. If it works, the packages is left in
3824 a "Config Files" state.
3827 Otherwise (i.e., the package was completely purged):
3828 <example compact="compact">
3829 <var>new-preinst</var> install
3832 <example compact="compact">
3833 <var>new-postrm</var> abort-install
3835 If the error-unwind fails, the package is in a
3836 "Half Installed" phase, and requires a
3837 reinstall. If the error unwind works, the
3838 package is in a not installed state.
3845 The new package's files are unpacked, overwriting any
3846 that may be on the system already, for example any
3847 from the old version of the same package or from
3848 another package. Backups of the old files are kept
3849 temporarily, and if anything goes wrong the package
3850 management system will attempt to put them back as
3851 part of the error unwind.
3855 It is an error for a package to contain files which
3856 are on the system in another package, unless
3857 <tt>Replaces</tt> is used (see <ref id="replaces">).
3859 The following paragraph is not currently the case:
3860 Currently the <tt>- - force-overwrite</tt> flag is
3861 enabled, downgrading it to a warning, but this may not
3867 It is a more serious error for a package to contain a
3868 plain file or other kind of non-directory where another
3869 package has a directory (again, unless
3870 <tt>Replaces</tt> is used). This error can be
3871 overridden if desired using
3872 <tt>--force-overwrite-dir</tt>, but this is not
3877 Packages which overwrite each other's files produce
3878 behavior which, though deterministic, is hard for the
3879 system administrator to understand. It can easily
3880 lead to "missing" programs if, for example, a package
3881 is unpacked which overwrites a file from another
3882 package, and is then removed again.<footnote>
3883 Part of the problem is due to what is arguably a
3884 bug in <prgn>dpkg</prgn>.
3889 A directory will never be replaced by a symbolic link
3890 to a directory or vice versa; instead, the existing
3891 state (symlink or not) will be left alone and
3892 <prgn>dpkg</prgn> will follow the symlink if there is
3901 If the package is being upgraded, call
3902 <example compact="compact">
3903 <var>old-postrm</var> upgrade <var>new-version</var>
3907 If this fails, <prgn>dpkg</prgn> will attempt:
3908 <example compact="compact">
3909 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3911 If this works, installation continues. If not,
3913 <example compact="compact">
3914 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3916 If this fails, the old version is left in an
3917 "Half Installed" state. If it works, dpkg now
3919 <example compact="compact">
3920 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3922 If this fails, the old version is left in an
3923 "Half Installed" state. If it works, dpkg now
3925 <example compact="compact">
3926 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3928 If this fails, the old version is in an
3935 This is the point of no return - if
3936 <prgn>dpkg</prgn> gets this far, it won't back off
3937 past this point if an error occurs. This will
3938 leave the package in a fairly bad state, which
3939 will require a successful re-installation to clear
3940 up, but it's when <prgn>dpkg</prgn> starts doing
3941 things that are irreversible.
3946 Any files which were in the old version of the package
3947 but not in the new are removed.
3951 The new file list replaces the old.
3955 The new maintainer scripts replace the old.
3959 Any packages all of whose files have been overwritten
3960 during the installation, and which aren't required for
3961 dependencies, are considered to have been removed.
3962 For each such package
3965 <prgn>dpkg</prgn> calls:
3966 <example compact="compact">
3967 <var>disappearer's-postrm</var> disappear \
3968 <var>overwriter</var> <var>overwriter-version</var>
3972 The package's maintainer scripts are removed.
3975 It is noted in the status database as being in a
3976 sane state, namely not installed (any conffiles
3977 it may have are ignored, rather than being
3978 removed by <prgn>dpkg</prgn>). Note that
3979 disappearing packages do not have their prerm
3980 called, because <prgn>dpkg</prgn> doesn't know
3981 in advance that the package is going to
3988 Any files in the package we're unpacking that are also
3989 listed in the file lists of other packages are removed
3990 from those lists. (This will lobotomize the file list
3991 of the "conflicting" package if there is one.)
3995 The backup files made during installation, above, are
4001 The new package's status is now sane, and recorded as
4006 Here is another point of no return - if the
4007 conflicting package's removal fails we do not unwind
4008 the rest of the installation; the conflicting package
4009 is left in a half-removed limbo.
4014 If there was a conflicting package we go and do the
4015 removal actions (described below), starting with the
4016 removal of the conflicting package's files (any that
4017 are also in the package being unpacked have already
4018 been removed from the conflicting package's file list,
4019 and so do not get removed now).
4025 <sect id="configdetails"><heading>Details of configuration</heading>
4028 When we configure a package (this happens with <tt>dpkg
4029 --install</tt> and <tt>dpkg --configure</tt>), we first
4030 update any <tt>conffile</tt>s and then call:
4031 <example compact="compact">
4032 <var>postinst</var> configure <var>most-recently-configured-version</var>
4037 No attempt is made to unwind after errors during
4038 configuration. If the configuration fails, the package is in
4039 a "Failed Config" state, and an error message is generated.
4043 If there is no most recently configured version
4044 <prgn>dpkg</prgn> will pass a null argument.
4047 Historical note: Truly ancient (pre-1997) versions of
4048 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4049 (including the angle brackets) in this case. Even older
4050 ones did not pass a second argument at all, under any
4051 circumstance. Note that upgrades using such an old dpkg
4052 version are unlikely to work for other reasons, even if
4053 this old argument behavior is handled by your postinst script.
4059 <sect id="removedetails"><heading>Details of removal and/or
4060 configuration purging</heading>
4066 <example compact="compact">
4067 <var>prerm</var> remove
4071 If prerm fails during replacement due to conflict
4073 <var>conflictor's-postinst</var> abort-remove \
4074 in-favour <var>package</var> <var>new-version</var>
4078 <var>postinst</var> abort-remove
4082 If this fails, the package is in a "Failed-Config"
4083 state, or else it remains "Installed".
4087 The package's files are removed (except <tt>conffile</tt>s).
4090 <example compact="compact">
4091 <var>postrm</var> remove
4095 If it fails, there's no error unwind, and the package is in
4096 an "Half-Installed" state.
4101 All the maintainer scripts except the <prgn>postrm</prgn>
4106 If we aren't purging the package we stop here. Note
4107 that packages which have no <prgn>postrm</prgn> and no
4108 <tt>conffile</tt>s are automatically purged when
4109 removed, as there is no difference except for the
4110 <prgn>dpkg</prgn> status.
4114 The <tt>conffile</tt>s and any backup files
4115 (<tt>~</tt>-files, <tt>#*#</tt> files,
4116 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4121 <example compact="compact">
4122 <var>postrm</var> purge
4126 If this fails, the package remains in a "Config-Files"
4131 The package's file list is removed.
4140 <chapt id="relationships">
4141 <heading>Declaring relationships between packages</heading>
4143 <sect id="depsyntax">
4144 <heading>Syntax of relationship fields</heading>
4147 These fields all have a uniform syntax. They are a list of
4148 package names separated by commas.
4152 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4153 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4154 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4155 control file fields of the package, which declare
4156 dependencies on other packages, the package names listed may
4157 also include lists of alternative package names, separated
4158 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4159 if any one of the alternative packages is installed, that
4160 part of the dependency is considered to be satisfied.
4164 All of the fields except for <tt>Provides</tt> may restrict
4165 their applicability to particular versions of each named
4166 package. This is done in parentheses after each individual
4167 package name; the parentheses should contain a relation from
4168 the list below followed by a version number, in the format
4169 described in <ref id="f-Version">.
4173 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4174 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4175 strictly earlier, earlier or equal, exactly equal, later or
4176 equal and strictly later, respectively. The deprecated
4177 forms <tt><</tt> and <tt>></tt> were used to mean
4178 earlier/later or equal, rather than strictly earlier/later,
4179 so they should not appear in new packages (though
4180 <prgn>dpkg</prgn> still supports them).
4184 Whitespace may appear at any point in the version
4185 specification subject to the rules in <ref
4186 id="controlsyntax">, and must appear where it's necessary to
4187 disambiguate; it is not otherwise significant. All of the
4188 relationship fields may span multiple lines. For
4189 consistency and in case of future changes to
4190 <prgn>dpkg</prgn> it is recommended that a single space be
4191 used after a version relationship and before a version
4192 number; it is also conventional to put a single space after
4193 each comma, on either side of each vertical bar, and before
4194 each open parenthesis. When wrapping a relationship field, it
4195 is conventional to do so after a comma and before the space
4196 following that comma.
4200 For example, a list of dependencies might appear as:
4201 <example compact="compact">
4204 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4209 All fields that specify build-time relationships
4210 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4211 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4212 may be restricted to a certain set of architectures. This
4213 is indicated in brackets after each individual package name and
4214 the optional version specification. The brackets enclose a
4215 list of Debian architecture names separated by whitespace.
4216 Exclamation marks may be prepended to each of the names.
4217 (It is not permitted for some names to be prepended with
4218 exclamation marks while others aren't.) If the current Debian
4219 host architecture is not in this list and there are no
4220 exclamation marks in the list, or it is in the list with a
4221 prepended exclamation mark, the package name and the
4222 associated version specification are ignored completely for
4223 the purposes of defining the relationships.
4228 <example compact="compact">
4230 Build-Depends-Indep: texinfo
4231 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4232 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4234 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4235 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4236 <tt>gnumach-dev</tt> only on hurd-i386.
4240 If the architecture-restricted dependency is part of a set of
4241 alternatives using <tt>|</tt>, that alternative is ignored
4242 completely on architectures that do not match the restriction.
4244 <example compact="compact">
4245 Build-Depends: foo [!i386] | bar [!amd64]
4247 is equivalent to <tt>bar</tt> on the i386 architecture, to
4248 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4249 bar</tt> on all other architectures.
4253 Note that the binary package relationship fields such as
4254 <tt>Depends</tt> appear in one of the binary package
4255 sections of the control file, whereas the build-time
4256 relationships such as <tt>Build-Depends</tt> appear in the
4257 source package section of the control file (which is the
4262 <sect id="binarydeps">
4263 <heading>Binary Dependencies - <tt>Depends</tt>,
4264 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4265 <tt>Pre-Depends</tt>
4269 Packages can declare in their control file that they have
4270 certain relationships to other packages - for example, that
4271 they may not be installed at the same time as certain other
4272 packages, and/or that they depend on the presence of others.
4276 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4277 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4278 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4279 <tt>Breaks</tt> is described in <ref id="breaks">, and
4280 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4281 rest are described below.
4285 These seven fields are used to declare a dependency
4286 relationship by one package on another. Except for
4287 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4288 depending (binary) package's control file.
4289 (<tt>Enhances</tt> appears in the recommending package's
4290 control file, and <tt>Breaks</tt> appears in the version of
4291 depended-on package which causes the named package to
4296 A <tt>Depends</tt> field takes effect <em>only</em> when a
4297 package is to be configured. It does not prevent a package
4298 being on the system in an unconfigured state while its
4299 dependencies are unsatisfied, and it is possible to replace
4300 a package whose dependencies are satisfied and which is
4301 properly installed with a different version whose
4302 dependencies are not and cannot be satisfied; when this is
4303 done the depending package will be left unconfigured (since
4304 attempts to configure it will give errors) and will not
4305 function properly. If it is necessary, a
4306 <tt>Pre-Depends</tt> field can be used, which has a partial
4307 effect even when a package is being unpacked, as explained
4308 in detail below. (The other three dependency fields,
4309 <tt>Recommends</tt>, <tt>Suggests</tt> and
4310 <tt>Enhances</tt>, are only used by the various front-ends
4311 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4312 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4316 Since <tt>Depends</tt> only places requirements on the
4317 configuration step, packages in an installation run are usually
4318 all unpacked first and all configured later. This makes it
4319 easier to satisfy all dependencies when multiple packages are
4324 If there is a circular dependency among packages being installed
4325 or removed, installation or removal order honoring the
4326 dependency order is impossible, requiring the dependency loop be
4327 broken at some point and the dependency requirements violated
4328 for at least one package. Packages involved in circular
4329 dependencies may not be able to rely on their dependencies being
4330 configured when being configured or removed depending on which
4331 side of the break of the circular dependency loop they happen to
4332 be on. If one of the packages in the loop has no
4333 <prgn>postinst</prgn> script, then the cycle will be broken at
4334 that package; this ensures that all <prgn>postinst</prgn>
4335 scripts are run with their dependencies properly configured if
4336 this is possible. Otherwise the breaking point is arbitrary.
4337 Packages should therefore avoid circular dependencies where
4338 possible, particularly if they have <prgn>postinst</prgn>
4343 The meaning of the five dependency fields is as follows:
4345 <tag><tt>Depends</tt></tag>
4348 This declares an absolute dependency. A package will
4349 not be configured unless all of the packages listed in
4350 its <tt>Depends</tt> field have been correctly
4351 configured (unless there is a circular dependency as
4356 The <tt>Depends</tt> field should be used if the
4357 depended-on package is required for the depending
4358 package to provide a significant amount of
4363 The <tt>Depends</tt> field should also be used if the
4364 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4365 <prgn>postrm</prgn> scripts require the package to be
4366 present in order to run. (If both packages are involved
4367 in a dependency loop, this might not work as expected; see
4368 the explanation a few paragraphs back.) In the case of
4369 <prgn>postinst</prgn> and <prgn>postrm</prgn>, the
4370 depended-on packages will be unpacked and configured
4371 first. (Note, however, that the <prgn>postrm</prgn>
4372 cannot rely on any non-essential packages to be present
4373 during the <tt>purge</tt> phase.) In the case of
4374 <prgn>prerm</prgn>, the depended-on package will at least
4375 be unpacked (it might be configured too, but you can't
4376 rely on this unless you use <tt>Pre-Depends</tt>).
4379 <tag><tt>Recommends</tt></tag>
4382 This declares a strong, but not absolute, dependency.
4386 The <tt>Recommends</tt> field should list packages
4387 that would be found together with this one in all but
4388 unusual installations.
4392 <tag><tt>Suggests</tt></tag>
4394 This is used to declare that one package may be more
4395 useful with one or more others. Using this field
4396 tells the packaging system and the user that the
4397 listed packages are related to this one and can
4398 perhaps enhance its usefulness, but that installing
4399 this one without them is perfectly reasonable.
4402 <tag><tt>Enhances</tt></tag>
4404 This field is similar to Suggests but works in the
4405 opposite direction. It is used to declare that a
4406 package can enhance the functionality of another
4410 <tag><tt>Pre-Depends</tt></tag>
4413 This field is like <tt>Depends</tt>, except that it
4414 also forces <prgn>dpkg</prgn> to complete installation
4415 of the packages named before even starting the
4416 installation of the package which declares the
4417 pre-dependency, as follows:
4421 When a package declaring a pre-dependency is about to
4422 be <em>unpacked</em> the pre-dependency can be
4423 satisfied if the depended-on package is either fully
4424 configured, <em>or even if</em> the depended-on
4425 package(s) are only unpacked or half-configured,
4426 provided that they have been configured correctly at
4427 some point in the past (and not removed or partially
4428 removed since). In this case, both the
4429 previously-configured and currently unpacked or
4430 half-configured versions must satisfy any version
4431 clause in the <tt>Pre-Depends</tt> field.
4435 When the package declaring a pre-dependency is about
4436 to be <em>configured</em>, the pre-dependency will be
4437 treated as a normal <tt>Depends</tt>, that is, it will
4438 be considered satisfied only if the depended-on
4439 package has been correctly configured. However, unlike
4440 with <tt>Depends</tt>, <tt>Pre-Depends</tt> does not
4441 permit circular dependencies to be broken. If a circular
4442 dependency is encountered while attempting to honor
4443 <tt>Pre-Depends</tt>, the installation will be aborted.
4447 <tt>Pre-Depends</tt> are also required if the
4448 <prgn>preinst</prgn> script depends on the named package.
4449 It is best to avoid this situation if possible.
4453 <tt>Pre-Depends</tt> should be used sparingly,
4454 preferably only by packages whose premature upgrade or
4455 installation would hamper the ability of the system to
4456 continue with any upgrade that might be in progress.
4463 When selecting which level of dependency to use you should
4464 consider how important the depended-on package is to the
4465 functionality of the one declaring the dependency. Some
4466 packages are composed of components of varying degrees of
4467 importance. Such a package should list using
4468 <tt>Depends</tt> the package(s) which are required by the
4469 more important components. The other components'
4470 requirements may be mentioned as Suggestions or
4471 Recommendations, as appropriate to the components' relative
4477 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4480 When one binary package declares that it breaks another,
4481 <prgn>dpkg</prgn> will refuse to allow the package which
4482 declares <tt>Breaks</tt> be unpacked unless the broken
4483 package is deconfigured first, and it will refuse to
4484 allow the broken package to be reconfigured.
4488 A package will not be regarded as causing breakage merely
4489 because its configuration files are still installed; it must
4490 be at least half-installed.
4494 A special exception is made for packages which declare that
4495 they break their own package name or a virtual package which
4496 they provide (see below): this does not count as a real
4501 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4502 version clause; such a <tt>Breaks</tt> is introduced in the
4503 version of an (implicit or explicit) dependency which
4504 violates an assumption or reveals a bug in earlier versions
4505 of the broken package. This use of <tt>Breaks</tt> will
4506 inform higher-level package management tools that broken
4507 package must be upgraded before the new one.
4511 If the breaking package also overwrites some files from the
4512 older package, it should use <tt>Replaces</tt> (not
4513 <tt>Conflicts</tt>) to ensure this goes smoothly.
4517 <sect id="conflicts">
4518 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4521 When one binary package declares a conflict with another
4522 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4523 refuse to allow them to be unpacked on the system at the
4528 If one package is to be unpacked, the other must be removed
4529 first - if the package being unpacked is marked as
4530 replacing (see <ref id="replaces">) the one on the system,
4531 or the one on the system is marked as deselected, or both
4532 packages are marked <tt>Essential</tt>, then
4533 <prgn>dpkg</prgn> will automatically remove the package
4534 which is causing the conflict, otherwise it will halt the
4535 installation of the new package with an error. This
4536 mechanism is specifically designed to produce an error when
4537 the installed package is <tt>Essential</tt>, but the new
4542 A package will not cause a conflict merely because its
4543 configuration files are still installed; it must be at least
4548 A special exception is made for packages which declare a
4549 conflict with their own package name, or with a virtual
4550 package which they provide (see below): this does not
4551 prevent their installation, and allows a package to conflict
4552 with others providing a replacement for it. You use this
4553 feature when you want the package in question to be the only
4554 package providing some feature.
4558 A <tt>Conflicts</tt> entry should almost never have an
4559 "earlier than" version clause. This would prevent
4560 <prgn>dpkg</prgn> from upgrading or installing the package
4561 which declared such a conflict until the upgrade or removal
4562 of the conflicted-with package had been completed. Instead,
4563 <tt>Breaks</tt> may be used.
4567 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4571 As well as the names of actual ("concrete") packages, the
4572 package relationship fields <tt>Depends</tt>,
4573 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4574 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4575 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4576 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4577 may mention "virtual packages".
4581 A <em>virtual package</em> is one which appears in the
4582 <tt>Provides</tt> control file field of another package.
4583 The effect is as if the package(s) which provide a
4584 particular virtual package name had been listed by name
4585 everywhere the virtual package name appears. (See also <ref
4590 If there are both concrete and virtual packages of the same
4591 name, then the dependency may be satisfied (or the conflict
4592 caused) by either the concrete package with the name in
4593 question or any other concrete package which provides the
4594 virtual package with the name in question. This is so that,
4595 for example, supposing we have
4596 <example compact="compact">
4599 </example> and someone else releases an enhanced version of
4600 the <tt>bar</tt> package they can say:
4601 <example compact="compact">
4605 and the <tt>bar-plus</tt> package will now also satisfy the
4606 dependency for the <tt>foo</tt> package.
4610 If a relationship field has a version number attached
4611 then only real packages will be considered to see whether
4612 the relationship is satisfied (or the prohibition violated,
4613 for a conflict or breakage) - it is assumed that a real
4614 package which provides the virtual package is not of the
4615 "right" version. So, a <tt>Provides</tt> field may not
4616 contain version numbers, and the version number of the
4617 concrete package which provides a particular virtual package
4618 will not be looked at when considering a dependency on or
4619 conflict with the virtual package name.
4623 It is likely that the ability will be added in a future
4624 release of <prgn>dpkg</prgn> to specify a version number for
4625 each virtual package it provides. This feature is not yet
4626 present, however, and is expected to be used only
4631 If you want to specify which of a set of real packages
4632 should be the default to satisfy a particular dependency on
4633 a virtual package, you should list the real package as an
4634 alternative before the virtual one.
4639 <sect id="replaces"><heading>Overwriting files and replacing
4640 packages - <tt>Replaces</tt></heading>
4643 Packages can declare in their control file that they should
4644 overwrite files in certain other packages, or completely
4645 replace other packages. The <tt>Replaces</tt> control file
4646 field has these two distinct purposes.
4649 <sect1><heading>Overwriting files in other packages</heading>
4652 Firstly, as mentioned before, it is usually an error for a
4653 package to contain files which are on the system in
4658 However, if the overwriting package declares that it
4659 <tt>Replaces</tt> the one containing the file being
4660 overwritten, then <prgn>dpkg</prgn> will replace the file
4661 from the old package with that from the new. The file
4662 will no longer be listed as "owned" by the old package.
4666 If a package is completely replaced in this way, so that
4667 <prgn>dpkg</prgn> does not know of any files it still
4668 contains, it is considered to have "disappeared". It will
4669 be marked as not wanted on the system (selected for
4670 removal) and not installed. Any <tt>conffile</tt>s
4671 details noted for the package will be ignored, as they
4672 will have been taken over by the overwriting package. The
4673 package's <prgn>postrm</prgn> script will be run with a
4674 special argument to allow the package to do any final
4675 cleanup required. See <ref id="mscriptsinstact">.
4678 Replaces is a one way relationship -- you have to
4679 install the replacing package after the replaced
4686 For this usage of <tt>Replaces</tt>, virtual packages (see
4687 <ref id="virtual">) are not considered when looking at a
4688 <tt>Replaces</tt> field - the packages declared as being
4689 replaced must be mentioned by their real names.
4693 Furthermore, this usage of <tt>Replaces</tt> only takes
4694 effect when both packages are at least partially on the
4695 system at once, so that it can only happen if they do not
4696 conflict or if the conflict has been overridden.
4701 <sect1><heading>Replacing whole packages, forcing their
4705 Secondly, <tt>Replaces</tt> allows the packaging system to
4706 resolve which package should be removed when there is a
4707 conflict - see <ref id="conflicts">. This usage only
4708 takes effect when the two packages <em>do</em> conflict,
4709 so that the two usages of this field do not interfere with
4714 In this situation, the package declared as being replaced
4715 can be a virtual package, so for example, all mail
4716 transport agents (MTAs) would have the following fields in
4717 their control files:
4718 <example compact="compact">
4719 Provides: mail-transport-agent
4720 Conflicts: mail-transport-agent
4721 Replaces: mail-transport-agent
4723 ensuring that only one MTA can be unpacked at any one
4728 <sect id="sourcebinarydeps">
4729 <heading>Relationships between source and binary packages -
4730 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4731 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4735 Source packages that require certain binary packages to be
4736 installed or absent at the time of building the package
4737 can declare relationships to those binary packages.
4741 This is done using the <tt>Build-Depends</tt>,
4742 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4743 <tt>Build-Conflicts-Indep</tt> control file fields.
4747 Build-dependencies on "build-essential" binary packages can be
4748 omitted. Please see <ref id="pkg-relations"> for more information.
4752 The dependencies and conflicts they define must be satisfied
4753 (as defined earlier for binary packages) in order to invoke
4754 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4756 If you make "build-arch" or "binary-arch", you need
4757 Build-Depends. If you make "build-indep" or
4758 "binary-indep", you need Build-Depends and
4759 Build-Depends-Indep. If you make "build" or "binary",
4763 There is no Build-Depends-Arch; this role is essentially
4764 met with Build-Depends. Anyone building the
4765 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4766 is basically assumed to be building the whole package
4767 anyway and so installs all build dependencies. The
4768 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4769 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4770 does not yet know how to check for its existence) and
4771 <tt>binary-arch</tt>.
4774 The purpose of the original split, I recall, was so that
4775 the autobuilders wouldn't need to install extra packages
4776 needed only for the binary-indep targets. But without a
4777 build-arch/build-indep split, this didn't work, since
4778 most of the work is done in the build target, not in the
4784 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4786 The <tt>Build-Depends</tt> and
4787 <tt>Build-Conflicts</tt> fields must be satisfied when
4788 any of the following targets is invoked:
4789 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4790 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4791 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4793 <tag><tt>Build-Depends-Indep</tt>,
4794 <tt>Build-Conflicts-Indep</tt></tag>
4796 The <tt>Build-Depends-Indep</tt> and
4797 <tt>Build-Conflicts-Indep</tt> fields must be
4798 satisfied when any of the following targets is
4799 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4800 <tt>binary</tt> and <tt>binary-indep</tt>.
4810 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4813 Packages containing shared libraries must be constructed with
4814 a little care to make sure that the shared library is always
4815 available. This is especially important for packages whose
4816 shared libraries are vitally important, such as the C library
4817 (currently <tt>libc6</tt>).
4821 Packages involving shared libraries should be split up into
4822 several binary packages. This section mostly deals with how
4823 this separation is to be accomplished; rules for files within
4824 the shared library packages are in <ref id="libraries"> instead.
4827 <sect id="sharedlibs-runtime">
4828 <heading>Run-time shared libraries</heading>
4831 The run-time shared library needs to be placed in a package
4832 whose name changes whenever the shared object version
4835 Since it is common place to install several versions of a
4836 package that just provides shared libraries, it is a
4837 good idea that the library package should not
4838 contain any extraneous non-versioned files, unless they
4839 happen to be in versioned directories.</p>
4841 The most common mechanism is to place it in a package
4843 <package><var>libraryname</var><var>soversion</var></package>,
4844 where <file><var>soversion</var></file> is the version number
4845 in the soname of the shared library<footnote>
4846 The soname is the shared object name: it's the thing
4847 that has to match exactly between building an executable
4848 and running it for the dynamic linker to be able run the
4849 program. For example, if the soname of the library is
4850 <file>libfoo.so.6</file>, the library package would be
4851 called <file>libfoo6</file>.
4853 Alternatively, if it would be confusing to directly append
4854 <var>soversion</var> to <var>libraryname</var> (e.g. because
4855 <var>libraryname</var> itself ends in a number), you may use
4856 <package><var>libraryname</var>-<var>soversion</var></package> and
4857 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4862 If you have several shared libraries built from the same
4863 source tree you may lump them all together into a single
4864 shared library package, provided that you change all of
4865 their sonames at once (so that you don't get filename
4866 clashes if you try to install different versions of the
4867 combined shared libraries package).
4871 The package should install the shared libraries under
4872 their normal names. For example, the <package>libgdbm3</package>
4873 package should install <file>libgdbm.so.3.0.0</file> as
4874 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4875 renamed or re-linked by any <prgn>prerm</prgn> or
4876 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4877 of renaming things safely without affecting running programs,
4878 and attempts to interfere with this are likely to lead to
4883 Shared libraries should not be installed executable, since
4884 the dynamic linker does not require this and trying to
4885 execute a shared library usually results in a core dump.
4889 The run-time library package should include the symbolic link that
4890 <prgn>ldconfig</prgn> would create for the shared libraries.
4891 For example, the <package>libgdbm3</package> package should include
4892 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4893 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4894 linker (for example <prgn>ld.so</prgn> or
4895 <prgn>ld-linux.so.*</prgn>) can find the library between the
4896 time that <prgn>dpkg</prgn> installs it and the time that
4897 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4899 The package management system requires the library to be
4900 placed before the symbolic link pointing to it in the
4901 <file>.deb</file> file. This is so that when
4902 <prgn>dpkg</prgn> comes to install the symlink
4903 (overwriting the previous symlink pointing at an older
4904 version of the library), the new shared library is already
4905 in place. In the past, this was achieved by creating the
4906 library in the temporary packaging directory before
4907 creating the symlink. Unfortunately, this was not always
4908 effective, since the building of the tar file in the
4909 <file>.deb</file> depended on the behavior of the underlying
4910 file system. Some file systems (such as reiserfs) reorder
4911 the files so that the order of creation is forgotten.
4912 Since version 1.7.0, <prgn>dpkg</prgn>
4913 reorders the files itself as necessary when building a
4914 package. Thus it is no longer important to concern
4915 oneself with the order of file creation.
4919 <sect1 id="ldconfig">
4920 <heading><tt>ldconfig</tt></heading>
4923 Any package installing shared libraries in one of the default
4924 library directories of the dynamic linker (which are currently
4925 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4926 listed in <file>/etc/ld.so.conf</file><footnote>
4928 <list compact="compact">
4929 <item>/usr/local/lib</item>
4930 <item>/usr/lib/libc5-compat</item>
4931 <item>/lib/libc5-compat</item>
4934 must use <prgn>ldconfig</prgn> to update the shared library
4939 The package maintainer scripts must only call
4940 <prgn>ldconfig</prgn> under these circumstances:
4941 <list compact="compact">
4942 <item>When the <prgn>postinst</prgn> script is run with a
4943 first argument of <tt>configure</tt>, the script must call
4944 <prgn>ldconfig</prgn>, and may optionally invoke
4945 <prgn>ldconfig</prgn> at other times.
4947 <item>When the <prgn>postrm</prgn> script is run with a
4948 first argument of <tt>remove</tt>, the script should call
4949 <prgn>ldconfig</prgn>.
4954 During install or upgrade, the preinst is called before
4955 the new files are unpacked, so calling "ldconfig" is
4956 pointless. The preinst of an existing package can also be
4957 called if an upgrade fails. However, this happens during
4958 the critical time when a shared libs may exist on-disk
4959 under a temporary name. Thus, it is dangerous and
4960 forbidden by current policy to call "ldconfig" at this
4965 When a package is installed or upgraded, "postinst
4966 configure" runs after the new files are safely on-disk.
4967 Since it is perfectly safe to invoke ldconfig
4968 unconditionally in a postinst, it is OK for a package to
4969 simply put ldconfig in its postinst without checking the
4970 argument. The postinst can also be called to recover from
4971 a failed upgrade. This happens before any new files are
4972 unpacked, so there is no reason to call "ldconfig" at this
4977 For a package that is being removed, prerm is
4978 called with all the files intact, so calling ldconfig is
4979 useless. The other calls to "prerm" happen in the case of
4980 upgrade at a time when all the files of the old package
4981 are on-disk, so again calling "ldconfig" is pointless.
4985 postrm, on the other hand, is called with the "remove"
4986 argument just after the files are removed, so this is
4987 the proper time to call "ldconfig" to notify the system
4988 of the fact that the shared libraries from the package
4989 are removed. The postrm can be called at several other
4990 times. At the time of "postrm purge", "postrm
4991 abort-install", or "postrm abort-upgrade", calling
4992 "ldconfig" is useless because the shared lib files are
4993 not on-disk. However, when "postrm" is invoked with
4994 arguments "upgrade", "failed-upgrade", or "disappear", a
4995 shared lib may exist on-disk under a temporary filename.
5003 <sect id="sharedlibs-support-files">
5004 <heading>Shared library support files</heading>
5007 If your package contains files whose names do not change with
5008 each change in the library shared object version, you must not
5009 put them in the shared library package. Otherwise, several
5010 versions of the shared library cannot be installed at the same
5011 time without filename clashes, making upgrades and transitions
5012 unnecessarily difficult.
5016 It is recommended that supporting files and run-time support
5017 programs that do not need to be invoked manually by users, but
5018 are nevertheless required for the package to function, be placed
5019 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5020 preferably under <file>/usr/lib/</file><var>package-name</var>.
5021 If the program or file is architecture independent, the
5022 recommendation is for it to be placed in a subdirectory of
5023 <file>/usr/share</file> instead, preferably under
5024 <file>/usr/share/</file><var>package-name</var>. Following the
5025 <var>package-name</var> naming convention ensures that the file
5026 names change when the shared object version changes.
5030 Run-time support programs that use the shared library but are
5031 not required for the library to function or files used by the
5032 shared library that can be used by any version of the shared
5033 library package should instead be put in a separate package.
5034 This package might typically be named
5035 <package><var>libraryname</var>-tools</package>; note the
5036 absence of the <var>soversion</var> in the package name.
5040 Files and support programs only useful when compiling software
5041 against the library should be included in the development
5042 package for the library.<footnote>
5043 For example, a <file><var>package-name</var>-config</file>
5044 script or <package>pkg-config</package> configuration files.
5049 <sect id="sharedlibs-static">
5050 <heading>Static libraries</heading>
5053 The static library (<file><var>libraryname.a</var></file>)
5054 is usually provided in addition to the shared version.
5055 It is placed into the development package (see below).
5059 In some cases, it is acceptable for a library to be
5060 available in static form only; these cases include:
5062 <item>libraries for languages whose shared library support
5063 is immature or unstable</item>
5064 <item>libraries whose interfaces are in flux or under
5065 development (commonly the case when the library's
5066 major version number is zero, or where the ABI breaks
5067 across patchlevels)</item>
5068 <item>libraries which are explicitly intended to be
5069 available only in static form by their upstream
5074 <sect id="sharedlibs-dev">
5075 <heading>Development files</heading>
5078 The development files associated to a shared library need to be
5079 placed in a package called
5080 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5081 or if you prefer only to support one development version at a
5082 time, <package><var>libraryname</var>-dev</package>.
5086 In case several development versions of a library exist, you may
5087 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5088 <ref id="conflicts">) to ensure that the user only installs one
5089 development version at a time (as different development versions are
5090 likely to have the same header files in them, which would cause a
5091 filename clash if both were unpacked).
5095 The development package should contain a symlink for the associated
5096 shared library without a version number. For example, the
5097 <package>libgdbm-dev</package> package should include a symlink
5098 from <file>/usr/lib/libgdbm.so</file> to
5099 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5100 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5101 <file>libgdbm.so</file> when compiling dynamically.
5105 <sect id="sharedlibs-intradeps">
5106 <heading>Dependencies between the packages of the same library</heading>
5109 Typically the development version should have an exact
5110 version dependency on the runtime library, to make sure that
5111 compilation and linking happens correctly. The
5112 <tt>${binary:Version}</tt> substitution variable can be
5113 useful for this purpose.
5115 Previously, <tt>${Source-Version}</tt> was used, but its name
5116 was confusing and it has been deprecated since dpkg 1.13.19.
5121 <sect id="sharedlibs-shlibdeps">
5122 <heading>Dependencies between the library and other packages -
5123 the <tt>shlibs</tt> system</heading>
5126 If a package contains a binary or library which links to a
5127 shared library, we must ensure that when the package is
5128 installed on the system, all of the libraries needed are
5129 also installed. This requirement led to the creation of the
5130 <tt>shlibs</tt> system, which is very simple in its design:
5131 any package which <em>provides</em> a shared library also
5132 provides information on the package dependencies required to
5133 ensure the presence of this library, and any package which
5134 <em>uses</em> a shared library uses this information to
5135 determine the dependencies it requires. The files which
5136 contain the mapping from shared libraries to the necessary
5137 dependency information are called <file>shlibs</file> files.
5141 Thus, when a package is built which contains any shared
5142 libraries, it must provide a <file>shlibs</file> file for other
5143 packages to use, and when a package is built which contains
5144 any shared libraries or compiled binaries, it must run
5145 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5146 on these to determine the libraries used and hence the
5147 dependencies needed by this package.<footnote>
5149 In the past, the shared libraries linked to were
5150 determined by calling <prgn>ldd</prgn>, but now
5151 <prgn>objdump</prgn> is used to do this. The only
5152 change this makes to package building is that
5153 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5154 libraries, whereas in the past this was unnecessary.
5155 The rest of this footnote explains the advantage that
5160 We say that a binary <tt>foo</tt> <em>directly</em> uses
5161 a library <tt>libbar</tt> if it is explicitly linked
5162 with that library (that is, it uses the flag
5163 <tt>-lbar</tt> during the linking stage). Other
5164 libraries that are needed by <tt>libbar</tt> are linked
5165 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5166 linker will load them automatically when it loads
5167 <tt>libbar</tt>. A package should depend on
5168 the libraries it directly uses, and the dependencies for
5169 those libraries should automatically pull in the other
5174 Unfortunately, the <prgn>ldd</prgn> program shows both
5175 the directly and indirectly used libraries, meaning that
5176 the dependencies determined included both direct and
5177 indirect dependencies. The use of <prgn>objdump</prgn>
5178 avoids this problem by determining only the directly
5183 A good example of where this helps is the following. We
5184 could update <tt>libimlib</tt> with a new version that
5185 supports a new graphics format called dgf (but retaining
5186 the same major version number). If we used the old
5187 <prgn>ldd</prgn> method, every package that uses
5188 <tt>libimlib</tt> would need to be recompiled so it
5189 would also depend on <tt>libdgf</tt> or it wouldn't run
5190 due to missing symbols. However with the new system,
5191 packages using <tt>libimlib</tt> can rely on
5192 <tt>libimlib</tt> itself having the dependency on
5193 <tt>libdgf</tt> and so they would not need rebuilding.
5199 In the following sections, we will first describe where the
5200 various <tt>shlibs</tt> files are to be found, then how to
5201 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5202 file format and how to create them if your package contains a
5207 <heading>The <tt>shlibs</tt> files present on the system</heading>
5210 There are several places where <tt>shlibs</tt> files are
5211 found. The following list gives them in the order in which
5213 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5214 (The first one which gives the required information is used.)
5220 <p><file>debian/shlibs.local</file></p>
5223 This lists overrides for this package. Its use is
5224 described below (see <ref id="shlibslocal">).
5229 <p><file>/etc/dpkg/shlibs.override</file></p>
5232 This lists global overrides. This list is normally
5233 empty. It is maintained by the local system
5239 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5242 When packages are being built, any
5243 <file>debian/shlibs</file> files are copied into the
5244 control file area of the temporary build directory and
5245 given the name <file>shlibs</file>. These files give
5246 details of any shared libraries included in the
5248 An example may help here. Let us say that the
5249 source package <tt>foo</tt> generates two binary
5250 packages, <tt>libfoo2</tt> and
5251 <tt>foo-runtime</tt>. When building the binary
5252 packages, the two packages are created in the
5253 directories <file>debian/libfoo2</file> and
5254 <file>debian/foo-runtime</file> respectively.
5255 (<file>debian/tmp</file> could be used instead of one
5256 of these.) Since <tt>libfoo2</tt> provides the
5257 <tt>libfoo</tt> shared library, it will require a
5258 <tt>shlibs</tt> file, which will be installed in
5259 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5261 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5262 when <prgn>dpkg-shlibdeps</prgn> is run on the
5264 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5266 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5267 determine whether <tt>foo-prog</tt>'s library
5268 dependencies are satisfied by any of the libraries
5269 provided by <tt>libfoo2</tt>. For this reason,
5270 <prgn>dpkg-shlibdeps</prgn> must only be run once
5271 all of the individual binary packages'
5272 <tt>shlibs</tt> files have been installed into the
5279 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5282 These are the <file>shlibs</file> files corresponding to
5283 all of the packages installed on the system, and are
5284 maintained by the relevant package maintainers.
5289 <p><file>/etc/dpkg/shlibs.default</file></p>
5292 This file lists any shared libraries whose packages
5293 have failed to provide correct <file>shlibs</file> files.
5294 It was used when the <file>shlibs</file> setup was first
5295 introduced, but it is now normally empty. It is
5296 maintained by the <tt>dpkg</tt> maintainer.
5304 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5305 <file>shlibs</file> files</heading>
5309 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5310 into your <file>debian/rules</file> file. If your package
5311 contains only compiled binaries and libraries (but no scripts),
5312 you can use a command such as:
5313 <example compact="compact">
5314 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5315 debian/tmp/usr/lib/*
5317 Otherwise, you will need to explicitly list the compiled
5318 binaries and libraries.<footnote>
5319 If you are using <tt>debhelper</tt>, the
5320 <prgn>dh_shlibdeps</prgn> program will do this work for
5321 you. It will also correctly handle multi-binary
5327 This command puts the dependency information into the
5328 <file>debian/substvars</file> file, which is then used by
5329 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5330 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5331 field in the control file for this to work.
5335 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5336 done. If it does complain you might need to create your own
5337 <file>debian/shlibs.local</file> file, as explained below (see
5338 <ref id="shlibslocal">).
5342 If you have multiple binary packages, you will need to call
5343 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5344 compiled libraries or binaries. In such a case, you will
5345 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5346 utilities to specify a different <file>substvars</file> file.
5350 If you are creating a udeb for use in the Debian Installer, you
5351 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5352 the dependency line of type <tt>udeb</tt> by adding
5353 <tt>-tudeb</tt> as option<footnote>
5354 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5355 will automatically add this option if it knows it is
5357 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5358 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5359 fall back to the regular dependency line.
5363 For more details on dpkg-shlibdeps, please see
5364 <ref id="pkg-dpkg-shlibdeps"> and
5365 <manref name="dpkg-shlibdeps" section="1">.
5370 <heading>The <file>shlibs</file> File Format</heading>
5373 Each <file>shlibs</file> file has the same format. Lines
5374 beginning with <tt>#</tt> are considered to be comments and
5375 are ignored. Each line is of the form:
5376 <example compact="compact">
5377 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5382 We will explain this by reference to the example of the
5383 <tt>zlib1g</tt> package, which (at the time of writing)
5384 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5388 <var>type</var> is an optional element that indicates the type
5389 of package for which the line is valid. The only type currently
5390 in use is <tt>udeb</tt>. The colon and space after the type are
5395 <var>library-name</var> is the name of the shared library,
5396 in this case <tt>libz</tt>. (This must match the name part
5397 of the soname, see below.)
5401 <var>soname-version</var> is the version part of the soname of
5402 the library. The soname is the thing that must exactly match
5403 for the library to be recognized by the dynamic linker, and is
5405 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5406 example, <tt>libz.so.1</tt>.<footnote>
5407 This can be determined using the command
5408 <example compact="compact">
5409 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5412 The version part is the part which comes after
5413 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5417 <var>dependencies</var> has the same syntax as a dependency
5418 field in a binary package control file. It should give
5419 details of which packages are required to satisfy a binary
5420 built against the version of the library contained in the
5421 package. See <ref id="depsyntax"> for details.
5425 In our example, if the first version of the <tt>zlib1g</tt>
5426 package which contained a minor number of at least
5427 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5428 <tt>shlibs</tt> entry for this library could say:
5429 <example compact="compact">
5430 libz 1 zlib1g (>= 1:1.1.3)
5432 The version-specific dependency is to avoid warnings from
5433 the dynamic linker about using older shared libraries with
5438 As zlib1g also provides a udeb containing the shared library,
5439 there would also be a second line:
5440 <example compact="compact">
5441 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5447 <heading>Providing a <file>shlibs</file> file</heading>
5450 If your package provides a shared library, you need to create
5451 a <file>shlibs</file> file following the format described above.
5452 It is usual to call this file <file>debian/shlibs</file> (but if
5453 you have multiple binary packages, you might want to call it
5454 <file>debian/shlibs.<var>package</var></file> instead). Then
5455 let <file>debian/rules</file> install it in the control area:
5456 <example compact="compact">
5457 install -m644 debian/shlibs debian/tmp/DEBIAN
5459 or, in the case of a multi-binary package:
5460 <example compact="compact">
5461 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5463 An alternative way of doing this is to create the
5464 <file>shlibs</file> file in the control area directly from
5465 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5466 file at all,<footnote>
5467 This is what <prgn>dh_makeshlibs</prgn> in the
5468 <tt>debhelper</tt> suite does. If your package also has a udeb
5469 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5470 automatically generate the <tt>udeb:</tt> lines if you specify
5471 the name of the udeb with the <tt>--add-udeb</tt> option.
5473 since the <file>debian/shlibs</file> file itself is ignored by
5474 <prgn>dpkg-shlibdeps</prgn>.
5478 As <prgn>dpkg-shlibdeps</prgn> reads the
5479 <file>DEBIAN/shlibs</file> files in all of the binary packages
5480 being built from this source package, all of the
5481 <file>DEBIAN/shlibs</file> files should be installed before
5482 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5487 <sect1 id="shlibslocal">
5488 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5491 This file is intended only as a <em>temporary</em> fix if
5492 your binaries or libraries depend on a library whose package
5493 does not yet provide a correct <file>shlibs</file> file.
5497 We will assume that you are trying to package a binary
5498 <tt>foo</tt>. When you try running
5499 <prgn>dpkg-shlibdeps</prgn> you get the following error
5500 message (<tt>-O</tt> displays the dependency information on
5501 <tt>stdout</tt> instead of writing it to
5502 <tt>debian/substvars</tt>, and the lines have been wrapped
5503 for ease of reading):
5504 <example compact="compact">
5505 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5506 dpkg-shlibdeps: warning: unable to find dependency
5507 information for shared library libbar (soname 1,
5508 path /usr/lib/libbar.so.1, dependency field Depends)
5509 shlibs:Depends=libc6 (>= 2.2.2-2)
5511 You can then run <prgn>ldd</prgn> on the binary to find the
5512 full location of the library concerned:
5513 <example compact="compact">
5515 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5516 libc.so.6 => /lib/libc.so.6 (0x40032000)
5517 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5519 So the <prgn>foo</prgn> binary depends on the
5520 <prgn>libbar</prgn> shared library, but no package seems to
5521 provide a <file>*.shlibs</file> file handling
5522 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5523 determine the package responsible:
5524 <example compact="compact">
5525 $ dpkg -S /usr/lib/libbar.so.1
5526 bar1: /usr/lib/libbar.so.1
5527 $ dpkg -s bar1 | grep Version
5530 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5531 is the one we are using. Now we can file a bug against the
5532 <tt>bar1</tt> package and create our own
5533 <file>debian/shlibs.local</file> to locally fix the problem.
5534 Including the following line into your
5535 <file>debian/shlibs.local</file> file:
5536 <example compact="compact">
5537 libbar 1 bar1 (>= 1.0-1)
5539 should allow the package build to work.
5543 As soon as the maintainer of <tt>bar1</tt> provides a
5544 correct <file>shlibs</file> file, you should remove this line
5545 from your <file>debian/shlibs.local</file> file. (You should
5546 probably also then have a versioned <tt>Build-Depends</tt>
5547 on <tt>bar1</tt> to help ensure that others do not have the
5548 same problem building your package.)
5557 <chapt id="opersys"><heading>The Operating System</heading>
5560 <heading>File system hierarchy</heading>
5564 <heading>File System Structure</heading>
5567 The location of all installed files and directories must
5568 comply with the Filesystem Hierarchy Standard (FHS),
5569 version 2.3, with the exceptions noted below, and except
5570 where doing so would violate other terms of Debian
5571 Policy. The following exceptions to the FHS apply:
5576 The optional rules related to user specific
5577 configuration files for applications are stored in
5578 the user's home directory are relaxed. It is
5579 recommended that such files start with the
5580 '<tt>.</tt>' character (a "dot file"), and if an
5581 application needs to create more than one dot file
5582 then the preferred placement is in a subdirectory
5583 with a name starting with a '.' character, (a "dot
5584 directory"). In this case it is recommended the
5585 configuration files not start with the '.'
5591 The requirement for amd64 to use <file>/lib64</file>
5592 for 64 bit binaries is removed.
5597 The requirement that
5598 <file>/usr/local/share/man</file> be "synonymous"
5599 with <file>/usr/local/man</file> is relaxed to a
5604 The requirement that windowmanagers with a single
5605 configuration file call it <file>system.*wmrc</file>
5606 is removed, as is the restriction that the window
5607 manager subdirectory be named identically to the
5608 window manager name itself.
5613 The requirement that boot manager configuration
5614 files live in <file>/etc</file>, or at least are
5615 symlinked there, is relaxed to a recommendation.
5622 The version of this document referred here can be
5623 found in the <tt>debian-policy</tt> package or on <url
5624 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5625 name="FHS (Debian copy)"> alongside this manual (or, if
5626 you have the <package>debian-policy</package> installed,
5628 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5629 (local copy)">). The
5630 latest version, which may be a more recent version, may
5632 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5633 Specific questions about following the standard may be
5634 asked on the <tt>debian-devel</tt> mailing list, or
5635 referred to the FHS mailing list (see the
5636 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5642 <heading>Site-specific programs</heading>
5645 As mandated by the FHS, packages must not place any
5646 files in <file>/usr/local</file>, either by putting them in
5647 the file system archive to be unpacked by <prgn>dpkg</prgn>
5648 or by manipulating them in their maintainer scripts.
5652 However, the package may create empty directories below
5653 <file>/usr/local</file> so that the system administrator knows
5654 where to place site-specific files. These are not
5655 directories <em>in</em> <file>/usr/local</file>, but are
5656 children of directories in <file>/usr/local</file>. These
5657 directories (<file>/usr/local/*/dir/</file>)
5658 should be removed on package removal if they are
5663 Note, that this applies only to directories <em>below</em>
5664 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5665 Packages must not create sub-directories in the directory
5666 <file>/usr/local</file> itself, except those listed in FHS,
5667 section 4.5. However, you may create directories below
5668 them as you wish. You must not remove any of the
5669 directories listed in 4.5, even if you created them.
5673 Since <file>/usr/local</file> can be mounted read-only from a
5674 remote server, these directories must be created and
5675 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5676 maintainer scripts and not be included in the
5677 <file>.deb</file> archive. These scripts must not fail if
5678 either of these operations fail.
5682 For example, the <tt>emacsen-common</tt> package could
5683 contain something like
5684 <example compact="compact">
5685 if [ ! -e /usr/local/share/emacs ]
5687 if mkdir /usr/local/share/emacs 2>/dev/null
5689 chown root:staff /usr/local/share/emacs
5690 chmod 2775 /usr/local/share/emacs
5694 in its <prgn>postinst</prgn> script, and
5695 <example compact="compact">
5696 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5697 rmdir /usr/local/share/emacs 2>/dev/null || true
5699 in the <prgn>prerm</prgn> script. (Note that this form is
5700 used to ensure that if the script is interrupted, the
5701 directory <file>/usr/local/share/emacs</file> will still be
5706 If you do create a directory in <file>/usr/local</file> for
5707 local additions to a package, you should ensure that
5708 settings in <file>/usr/local</file> take precedence over the
5709 equivalents in <file>/usr</file>.
5713 However, because <file>/usr/local</file> and its contents are
5714 for exclusive use of the local administrator, a package
5715 must not rely on the presence or absence of files or
5716 directories in <file>/usr/local</file> for normal operation.
5720 The <file>/usr/local</file> directory itself and all the
5721 subdirectories created by the package should (by default) have
5722 permissions 2775 (group-writable and set-group-id) and be
5723 owned by <tt>root:staff</tt>.
5728 <heading>The system-wide mail directory</heading>
5730 The system-wide mail directory is <file>/var/mail</file>. This
5731 directory is part of the base system and should not owned
5732 by any particular mail agents. The use of the old
5733 location <file>/var/spool/mail</file> is deprecated, even
5734 though the spool may still be physically located there.
5740 <heading>Users and groups</heading>
5743 <heading>Introduction</heading>
5745 The Debian system can be configured to use either plain or
5750 Some user ids (UIDs) and group ids (GIDs) are reserved
5751 globally for use by certain packages. Because some
5752 packages need to include files which are owned by these
5753 users or groups, or need the ids compiled into binaries,
5754 these ids must be used on any Debian system only for the
5755 purpose for which they are allocated. This is a serious
5756 restriction, and we should avoid getting in the way of
5757 local administration policies. In particular, many sites
5758 allocate users and/or local system groups starting at 100.
5762 Apart from this we should have dynamically allocated ids,
5763 which should by default be arranged in some sensible
5764 order, but the behavior should be configurable.
5768 Packages other than <tt>base-passwd</tt> must not modify
5769 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5770 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5775 <heading>UID and GID classes</heading>
5777 The UID and GID numbers are divided into classes as
5783 Globally allocated by the Debian project, the same
5784 on every Debian system. These ids will appear in
5785 the <file>passwd</file> and <file>group</file> files of all
5786 Debian systems, new ids in this range being added
5787 automatically as the <tt>base-passwd</tt> package is
5792 Packages which need a single statically allocated
5793 uid or gid should use one of these; their
5794 maintainers should ask the <tt>base-passwd</tt>
5802 Dynamically allocated system users and groups.
5803 Packages which need a user or group, but can have
5804 this user or group allocated dynamically and
5805 differently on each system, should use <tt>adduser
5806 --system</tt> to create the group and/or user.
5807 <prgn>adduser</prgn> will check for the existence of
5808 the user or group, and if necessary choose an unused
5809 id based on the ranges specified in
5810 <file>adduser.conf</file>.
5814 <tag>1000-29999:</tag>
5817 Dynamically allocated user accounts. By default
5818 <prgn>adduser</prgn> will choose UIDs and GIDs for
5819 user accounts in this range, though
5820 <file>adduser.conf</file> may be used to modify this
5825 <tag>30000-59999:</tag>
5830 <tag>60000-64999:</tag>
5833 Globally allocated by the Debian project, but only
5834 created on demand. The ids are allocated centrally
5835 and statically, but the actual accounts are only
5836 created on users' systems on demand.
5840 These ids are for packages which are obscure or
5841 which require many statically-allocated ids. These
5842 packages should check for and create the accounts in
5843 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5844 <prgn>adduser</prgn> if it has this facility) if
5845 necessary. Packages which are likely to require
5846 further allocations should have a "hole" left after
5847 them in the allocation, to give them room to
5852 <tag>65000-65533:</tag>
5860 User <tt>nobody</tt>. The corresponding gid refers
5861 to the group <tt>nogroup</tt>.
5868 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5869 not</em> be used, because it is the error return
5878 <sect id="sysvinit">
5879 <heading>System run levels and <file>init.d</file> scripts</heading>
5881 <sect1 id="/etc/init.d">
5882 <heading>Introduction</heading>
5885 The <file>/etc/init.d</file> directory contains the scripts
5886 executed by <prgn>init</prgn> at boot time and when the
5887 init state (or "runlevel") is changed (see <manref
5888 name="init" section="8">).
5892 There are at least two different, yet functionally
5893 equivalent, ways of handling these scripts. For the sake
5894 of simplicity, this document describes only the symbolic
5895 link method. However, it must not be assumed by maintainer
5896 scripts that this method is being used, and any automated
5897 manipulation of the various runlevel behaviors by
5898 maintainer scripts must be performed using
5899 <prgn>update-rc.d</prgn> as described below and not by
5900 manually installing or removing symlinks. For information
5901 on the implementation details of the other method,
5902 implemented in the <tt>file-rc</tt> package, please refer
5903 to the documentation of that package.
5907 These scripts are referenced by symbolic links in the
5908 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5909 runlevels, <prgn>init</prgn> looks in the directory
5910 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5911 execute, where <tt><var>n</var></tt> is the runlevel that
5912 is being changed to, or <tt>S</tt> for the boot-up
5917 The names of the links all have the form
5918 <file>S<var>mm</var><var>script</var></file> or
5919 <file>K<var>mm</var><var>script</var></file> where
5920 <var>mm</var> is a two-digit number and <var>script</var>
5921 is the name of the script (this should be the same as the
5922 name of the actual script in <file>/etc/init.d</file>).
5926 When <prgn>init</prgn> changes runlevel first the targets
5927 of the links whose names start with a <tt>K</tt> are
5928 executed, each with the single argument <tt>stop</tt>,
5929 followed by the scripts prefixed with an <tt>S</tt>, each
5930 with the single argument <tt>start</tt>. (The links are
5931 those in the <file>/etc/rc<var>n</var>.d</file> directory
5932 corresponding to the new runlevel.) The <tt>K</tt> links
5933 are responsible for killing services and the <tt>S</tt>
5934 link for starting services upon entering the runlevel.
5938 For example, if we are changing from runlevel 2 to
5939 runlevel 3, init will first execute all of the <tt>K</tt>
5940 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5941 all of the <tt>S</tt> prefixed scripts in that directory.
5942 The links starting with <tt>K</tt> will cause the
5943 referred-to file to be executed with an argument of
5944 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5949 The two-digit number <var>mm</var> is used to determine
5950 the order in which to run the scripts: low-numbered links
5951 have their scripts run first. For example, the
5952 <tt>K20</tt> scripts will be executed before the
5953 <tt>K30</tt> scripts. This is used when a certain service
5954 must be started before another. For example, the name
5955 server <prgn>bind</prgn> might need to be started before
5956 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5957 can set up its access lists. In this case, the script
5958 that starts <prgn>bind</prgn> would have a lower number
5959 than the script that starts <prgn>inn</prgn> so that it
5961 <example compact="compact">
5968 The two runlevels 0 (halt) and 6 (reboot) are slightly
5969 different. In these runlevels, the links with an
5970 <tt>S</tt> prefix are still called after those with a
5971 <tt>K</tt> prefix, but they too are called with the single
5972 argument <tt>stop</tt>.
5977 <heading>Writing the scripts</heading>
5980 Packages that include daemons for system services should
5981 place scripts in <file>/etc/init.d</file> to start or stop
5982 services at boot time or during a change of runlevel.
5983 These scripts should be named
5984 <file>/etc/init.d/<var>package</var></file>, and they should
5985 accept one argument, saying what to do:
5988 <tag><tt>start</tt></tag>
5989 <item>start the service,</item>
5991 <tag><tt>stop</tt></tag>
5992 <item>stop the service,</item>
5994 <tag><tt>restart</tt></tag>
5995 <item>stop and restart the service if it's already running,
5996 otherwise start the service</item>
5998 <tag><tt>reload</tt></tag>
5999 <item><p>cause the configuration of the service to be
6000 reloaded without actually stopping and restarting
6003 <tag><tt>force-reload</tt></tag>
6004 <item>cause the configuration to be reloaded if the
6005 service supports this, otherwise restart the
6009 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6010 <tt>force-reload</tt> options should be supported by all
6011 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6016 The <file>init.d</file> scripts must ensure that they will
6017 behave sensibly (i.e., returning success and not starting
6018 multiple copies of a service) if invoked with <tt>start</tt>
6019 when the service is already running, or with <tt>stop</tt>
6020 when it isn't, and that they don't kill unfortunately-named
6021 user processes. The best way to achieve this is usually to
6022 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6027 If a service reloads its configuration automatically (as
6028 in the case of <prgn>cron</prgn>, for example), the
6029 <tt>reload</tt> option of the <file>init.d</file> script
6030 should behave as if the configuration has been reloaded
6035 The <file>/etc/init.d</file> scripts must be treated as
6036 configuration files, either (if they are present in the
6037 package, that is, in the .deb file) by marking them as
6038 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6039 by managing them correctly in the maintainer scripts (see
6040 <ref id="config-files">). This is important since we want
6041 to give the local system administrator the chance to adapt
6042 the scripts to the local system, e.g., to disable a
6043 service without de-installing the package, or to specify
6044 some special command line options when starting a service,
6045 while making sure their changes aren't lost during the next
6050 These scripts should not fail obscurely when the
6051 configuration files remain but the package has been
6052 removed, as configuration files remain on the system after
6053 the package has been removed. Only when <prgn>dpkg</prgn>
6054 is executed with the <tt>--purge</tt> option will
6055 configuration files be removed. In particular, as the
6056 <file>/etc/init.d/<var>package</var></file> script itself is
6057 usually a <tt>conffile</tt>, it will remain on the system
6058 if the package is removed but not purged. Therefore, you
6059 should include a <tt>test</tt> statement at the top of the
6061 <example compact="compact">
6062 test -f <var>program-executed-later-in-script</var> || exit 0
6067 Often there are some variables in the <file>init.d</file>
6068 scripts whose values control the behavior of the scripts,
6069 and which a system administrator is likely to want to
6070 change. As the scripts themselves are frequently
6071 <tt>conffile</tt>s, modifying them requires that the
6072 administrator merge in their changes each time the package
6073 is upgraded and the <tt>conffile</tt> changes. To ease
6074 the burden on the system administrator, such configurable
6075 values should not be placed directly in the script.
6076 Instead, they should be placed in a file in
6077 <file>/etc/default</file>, which typically will have the same
6078 base name as the <file>init.d</file> script. This extra file
6079 should be sourced by the script when the script runs. It
6080 must contain only variable settings and comments in SUSv3
6081 <prgn>sh</prgn> format. It may either be a
6082 <tt>conffile</tt> or a configuration file maintained by
6083 the package maintainer scripts. See <ref id="config-files">
6088 To ensure that vital configurable values are always
6089 available, the <file>init.d</file> script should set default
6090 values for each of the shell variables it uses, either
6091 before sourcing the <file>/etc/default/</file> file or
6092 afterwards using something like the <tt>:
6093 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6094 script must behave sensibly and not fail if the
6095 <file>/etc/default</file> file is deleted.
6099 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6100 as temporary filesystems<footnote>
6101 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6102 options in <file>/etc/default/rcS</file>.
6103 </footnote>, so the <file>init.d</file> scripts must handle this
6104 correctly. This will typically amount to creating any required
6105 subdirectories dynamically when the <file>init.d</file> script
6106 is run, rather than including them in the package and relying on
6107 <prgn>dpkg</prgn> to create them.
6112 <heading>Interfacing with the initscript system</heading>
6115 Maintainers should use the abstraction layer provided by
6116 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6117 programs to deal with initscripts in their packages'
6118 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6119 and <prgn>postrm</prgn>.
6123 Directly managing the /etc/rc?.d links and directly
6124 invoking the <file>/etc/init.d/</file> initscripts should
6125 be done only by packages providing the initscript
6126 subsystem (such as <prgn>sysv-rc</prgn> and
6127 <prgn>file-rc</prgn>).
6131 <heading>Managing the links</heading>
6134 The program <prgn>update-rc.d</prgn> is provided for
6135 package maintainers to arrange for the proper creation and
6136 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6137 or their functional equivalent if another method is being
6138 used. This may be used by maintainers in their packages'
6139 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6143 You must not include any <file>/etc/rc<var>n</var>.d</file>
6144 symbolic links in the actual archive or manually create or
6145 remove the symbolic links in maintainer scripts; you must
6146 use the <prgn>update-rc.d</prgn> program instead. (The
6147 former will fail if an alternative method of maintaining
6148 runlevel information is being used.) You must not include
6149 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6150 in the archive either. (Only the <tt>sysvinit</tt>
6155 By default <prgn>update-rc.d</prgn> will start services in
6156 each of the multi-user state runlevels (2, 3, 4, and 5)
6157 and stop them in the halt runlevel (0), the single-user
6158 runlevel (1) and the reboot runlevel (6). The system
6159 administrator will have the opportunity to customize
6160 runlevels by simply adding, moving, or removing the
6161 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6162 symbolic links are being used, or by modifying
6163 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6168 To get the default behavior for your package, put in your
6169 <prgn>postinst</prgn> script
6170 <example compact="compact">
6171 update-rc.d <var>package</var> defaults
6173 and in your <prgn>postrm</prgn>
6174 <example compact="compact">
6175 if [ "$1" = purge ]; then
6176 update-rc.d <var>package</var> remove
6178 </example>. Note that if your package changes runlevels
6179 or priority, you may have to remove and recreate the links,
6180 since otherwise the old links may persist. Refer to the
6181 documentation of <prgn>update-rc.d</prgn>.
6185 This will use a default sequence number of 20. If it does
6186 not matter when or in which order the <file>init.d</file>
6187 script is run, use this default. If it does, then you
6188 should talk to the maintainer of the <prgn>sysvinit</prgn>
6189 package or post to <tt>debian-devel</tt>, and they will
6190 help you choose a number.
6194 For more information about using <tt>update-rc.d</tt>,
6195 please consult its man page <manref name="update-rc.d"
6201 <heading>Running initscripts</heading>
6203 The program <prgn>invoke-rc.d</prgn> is provided to make
6204 it easier for package maintainers to properly invoke an
6205 initscript, obeying runlevel and other locally-defined
6206 constraints that might limit a package's right to start,
6207 stop and otherwise manage services. This program may be
6208 used by maintainers in their packages' scripts.
6212 The package maintainer scripts must use
6213 <prgn>invoke-rc.d</prgn> to invoke the
6214 <file>/etc/init.d/*</file> initscripts, instead of
6215 calling them directly.
6219 By default, <prgn>invoke-rc.d</prgn> will pass any
6220 action requests (start, stop, reload, restart...) to the
6221 <file>/etc/init.d</file> script, filtering out requests
6222 to start or restart a service out of its intended
6227 Most packages will simply need to change:
6228 <example compact="compact">/etc/init.d/<package>
6229 <action></example> in their <prgn>postinst</prgn>
6230 and <prgn>prerm</prgn> scripts to:
6231 <example compact="compact">
6232 if which invoke-rc.d >/dev/null 2>&1; then
6233 invoke-rc.d <var>package</var> <action>
6235 /etc/init.d/<var>package</var> <action>
6241 A package should register its initscript services using
6242 <prgn>update-rc.d</prgn> before it tries to invoke them
6243 using <prgn>invoke-rc.d</prgn>. Invocation of
6244 unregistered services may fail.
6248 For more information about using
6249 <prgn>invoke-rc.d</prgn>, please consult its man page
6250 <manref name="invoke-rc.d" section="8">.
6256 <heading>Boot-time initialization</heading>
6259 There used to be another directory, <file>/etc/rc.boot</file>,
6260 which contained scripts which were run once per machine
6261 boot. This has been deprecated in favour of links from
6262 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6263 described in <ref id="/etc/init.d">. Packages must not
6264 place files in <file>/etc/rc.boot</file>.
6269 <heading>Example</heading>
6272 An example on which you can base your
6273 <file>/etc/init.d</file> scripts is found in
6274 <file>/etc/init.d/skeleton</file>.
6281 <heading>Console messages from <file>init.d</file> scripts</heading>
6284 This section describes the formats to be used for messages
6285 written to standard output by the <file>/etc/init.d</file>
6286 scripts. The intent is to improve the consistency of
6287 Debian's startup and shutdown look and feel. For this
6288 reason, please look very carefully at the details. We want
6289 the messages to have the same format in terms of wording,
6290 spaces, punctuation and case of letters.
6294 Here is a list of overall rules that should be used for
6295 messages generated by <file>/etc/init.d</file> scripts.
6301 The message should fit in one line (fewer than 80
6302 characters), start with a capital letter and end with
6303 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6307 If the script is performing some time consuming task in
6308 the background (not merely starting or stopping a
6309 program, for instance), an ellipsis (three dots:
6310 <tt>...</tt>) should be output to the screen, with no
6311 leading or tailing whitespace or line feeds.
6315 The messages should appear as if the computer is telling
6316 the user what it is doing (politely :-), but should not
6317 mention "it" directly. For example, instead of:
6318 <example compact="compact">
6319 I'm starting network daemons: nfsd mountd.
6321 the message should say
6322 <example compact="compact">
6323 Starting network daemons: nfsd mountd.
6330 <tt>init.d</tt> script should use the following standard
6331 message formats for the situations enumerated below.
6337 <p>When daemons are started</p>
6340 If the script starts one or more daemons, the output
6341 should look like this (a single line, no leading
6343 <example compact="compact">
6344 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6346 The <var>description</var> should describe the
6347 subsystem the daemon or set of daemons are part of,
6348 while <var>daemon-1</var> up to <var>daemon-n</var>
6349 denote each daemon's name (typically the file name of
6354 For example, the output of <file>/etc/init.d/lpd</file>
6356 <example compact="compact">
6357 Starting printer spooler: lpd.
6362 This can be achieved by saying
6363 <example compact="compact">
6364 echo -n "Starting printer spooler: lpd"
6365 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6368 in the script. If there are more than one daemon to
6369 start, the output should look like this:
6370 <example compact="compact">
6371 echo -n "Starting remote file system services:"
6372 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6373 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6374 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6377 This makes it possible for the user to see what is
6378 happening and when the final daemon has been started.
6379 Care should be taken in the placement of white spaces:
6380 in the example above the system administrators can
6381 easily comment out a line if they don't want to start
6382 a specific daemon, while the displayed message still
6388 <p>When a system parameter is being set</p>
6391 If you have to set up different system parameters
6392 during the system boot, you should use this format:
6393 <example compact="compact">
6394 Setting <var>parameter</var> to "<var>value</var>".
6399 You can use a statement such as the following to get
6401 <example compact="compact">
6402 echo "Setting DNS domainname to \"$domainname\"."
6407 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6408 for the left and right quotation marks. A grave accent
6409 (<tt>`</tt>) is not a quote character; neither is an
6410 apostrophe (<tt>'</tt>).
6415 <p>When a daemon is stopped or restarted</p>
6418 When you stop or restart a daemon, you should issue a
6419 message identical to the startup message, except that
6420 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6421 or <tt>Restarting</tt> respectively.
6425 For example, stopping the printer daemon will look like
6427 <example compact="compact">
6428 Stopping printer spooler: lpd.
6434 <p>When something is executed</p>
6437 There are several examples where you have to run a
6438 program at system startup or shutdown to perform a
6439 specific task, for example, setting the system's clock
6440 using <prgn>netdate</prgn> or killing all processes
6441 when the system shuts down. Your message should look
6443 <example compact="compact">
6444 Doing something very useful...done.
6446 You should print the <tt>done.</tt> immediately after
6447 the job has been completed, so that the user is
6448 informed why they have to wait. You can get this
6450 <example compact="compact">
6451 echo -n "Doing something very useful..."
6460 <p>When the configuration is reloaded</p>
6463 When a daemon is forced to reload its configuration
6464 files you should use the following format:
6465 <example compact="compact">
6466 Reloading <var>description</var> configuration...done.
6468 where <var>description</var> is the same as in the
6469 daemon starting message.
6477 <heading>Cron jobs</heading>
6480 Packages must not modify the configuration file
6481 <file>/etc/crontab</file>, and they must not modify the files in
6482 <file>/var/spool/cron/crontabs</file>.</p>
6485 If a package wants to install a job that has to be executed
6486 via cron, it should place a file with the name of the
6487 package in one or more of the following directories:
6488 <example compact="compact">
6494 As these directory names imply, the files within them are
6495 executed on an hourly, daily, weekly, or monthly basis,
6496 respectively. The exact times are listed in
6497 <file>/etc/crontab</file>.</p>
6500 All files installed in any of these directories must be
6501 scripts (e.g., shell scripts or Perl scripts) so that they
6502 can easily be modified by the local system administrator.
6503 In addition, they must be treated as configuration files.
6507 If a certain job has to be executed at some other frequency or
6508 at a specific time, the package should install a file
6509 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6510 same syntax as <file>/etc/crontab</file> and is processed by
6511 <prgn>cron</prgn> automatically. The file must also be
6512 treated as a configuration file. (Note that entries in the
6513 <file>/etc/cron.d</file> directory are not handled by
6514 <prgn>anacron</prgn>. Thus, you should only use this
6515 directory for jobs which may be skipped if the system is not
6519 The scripts or crontab entries in these directories should
6520 check if all necessary programs are installed before they
6521 try to execute them. Otherwise, problems will arise when a
6522 package was removed but not purged since configuration files
6523 are kept on the system in this situation.</p>
6527 <heading>Menus</heading>
6530 The Debian <tt>menu</tt> package provides a standard
6531 interface between packages providing applications and
6532 <em>menu programs</em> (either X window managers or
6533 text-based menu programs such as <prgn>pdmenu</prgn>).
6537 All packages that provide applications that need not be
6538 passed any special command line arguments for normal
6539 operation should register a menu entry for those
6540 applications, so that users of the <tt>menu</tt> package
6541 will automatically get menu entries in their window
6542 managers, as well in shells like <tt>pdmenu</tt>.
6546 Menu entries should follow the current menu policy.
6550 The menu policy can be found in the <tt>menu-policy</tt>
6551 files in the <tt>debian-policy</tt> package.
6552 It is also available from the Debian web mirrors at
6553 <tt><url name="/doc/packaging-manuals/menu-policy/"
6554 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6558 Please also refer to the <em>Debian Menu System</em>
6559 documentation that comes with the <package>menu</package>
6560 package for information about how to register your
6566 <heading>Multimedia handlers</heading>
6569 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6570 is a mechanism for encoding files and data streams and
6571 providing meta-information about them, in particular their
6572 type (e.g. audio or video) and format (e.g. PNG, HTML,
6577 Registration of MIME type handlers allows programs like mail
6578 user agents and web browsers to invoke these handlers to
6579 view, edit or display MIME types they don't support directly.
6583 Packages which provide the ability to view/show/play,
6584 compose, edit or print MIME types should register themselves
6585 as such following the current MIME support policy.
6589 The MIME support policy can be found in the <tt>mime-policy</tt>
6590 files in the <tt>debian-policy</tt> package.
6591 It is also available from the Debian web mirrors at
6592 <tt><url name="/doc/packaging-manuals/mime-policy/"
6593 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6599 <heading>Keyboard configuration</heading>
6602 To achieve a consistent keyboard configuration so that all
6603 applications interpret a keyboard event the same way, all
6604 programs in the Debian distribution must be configured to
6605 comply with the following guidelines.
6609 The following keys must have the specified interpretations:
6612 <tag><tt><--</tt></tag>
6613 <item>delete the character to the left of the cursor</item>
6615 <tag><tt>Delete</tt></tag>
6616 <item>delete the character to the right of the cursor</item>
6618 <tag><tt>Control+H</tt></tag>
6619 <item>emacs: the help prefix</item>
6622 The interpretation of any keyboard events should be
6623 independent of the terminal that is used, be it a virtual
6624 console, an X terminal emulator, an rlogin/telnet session,
6629 The following list explains how the different programs
6630 should be set up to achieve this:
6636 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6640 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6644 X translations are set up to make
6645 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6646 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6647 is the vt220 escape code for the "delete character"
6648 key). This must be done by loading the X resources
6649 using <prgn>xrdb</prgn> on all local X displays, not
6650 using the application defaults, so that the
6651 translation resources used correspond to the
6652 <prgn>xmodmap</prgn> settings.
6656 The Linux console is configured to make
6657 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6658 generate <tt>ESC [ 3 ~</tt>.
6662 X applications are configured so that <tt><</tt>
6663 deletes left, and <tt>Delete</tt> deletes right. Motif
6664 applications already work like this.
6668 Terminals should have <tt>stty erase ^?</tt> .
6672 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6673 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6674 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6678 Emacs is programmed to map <tt>KB_Backspace</tt> or
6679 the <tt>stty erase</tt> character to
6680 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6681 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6682 <tt>^H</tt> to <tt>help</tt> as always.
6686 Other applications use the <tt>stty erase</tt>
6687 character and <tt>kdch1</tt> for the two delete keys,
6688 with ASCII DEL being "delete previous character" and
6689 <tt>kdch1</tt> being "delete character under
6697 This will solve the problem except for the following
6704 Some terminals have a <tt><--</tt> key that cannot
6705 be made to produce anything except <tt>^H</tt>. On
6706 these terminals Emacs help will be unavailable on
6707 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6708 character takes precedence in Emacs, and has been set
6709 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6710 available) can be used instead.
6714 Some operating systems use <tt>^H</tt> for <tt>stty
6715 erase</tt>. However, modern telnet versions and all
6716 rlogin versions propagate <tt>stty</tt> settings, and
6717 almost all UNIX versions honour <tt>stty erase</tt>.
6718 Where the <tt>stty</tt> settings are not propagated
6719 correctly, things can be made to work by using
6720 <tt>stty</tt> manually.
6724 Some systems (including previous Debian versions) use
6725 <prgn>xmodmap</prgn> to arrange for both
6726 <tt><--</tt> and <tt>Delete</tt> to generate
6727 <tt>KB_Delete</tt>. We can change the behavior of
6728 their X clients using the same X resources that we use
6729 to do it for our own clients, or configure our clients
6730 using their resources when things are the other way
6731 around. On displays configured like this
6732 <tt>Delete</tt> will not work, but <tt><--</tt>
6737 Some operating systems have different <tt>kdch1</tt>
6738 settings in their <tt>terminfo</tt> database for
6739 <tt>xterm</tt> and others. On these systems the
6740 <tt>Delete</tt> key will not work correctly when you
6741 log in from a system conforming to our policy, but
6742 <tt><--</tt> will.
6749 <heading>Environment variables</heading>
6752 A program must not depend on environment variables to get
6753 reasonable defaults. (That's because these environment
6754 variables would have to be set in a system-wide
6755 configuration file like <file>/etc/profile</file>, which is not
6756 supported by all shells.)
6760 If a program usually depends on environment variables for its
6761 configuration, the program should be changed to fall back to
6762 a reasonable default configuration if these environment
6763 variables are not present. If this cannot be done easily
6764 (e.g., if the source code of a non-free program is not
6765 available), the program must be replaced by a small
6766 "wrapper" shell script which sets the environment variables
6767 if they are not already defined, and calls the original program.
6771 Here is an example of a wrapper script for this purpose:
6773 <example compact="compact">
6775 BAR=${BAR:-/var/lib/fubar}
6777 exec /usr/lib/foo/foo "$@"
6782 Furthermore, as <file>/etc/profile</file> is a configuration
6783 file of the <prgn>base-files</prgn> package, other packages must
6784 not put any environment variables or other commands into that
6789 <sect id="doc-base">
6790 <heading>Registering Documents using doc-base</heading>
6793 The <package>doc-base</package> package implements a
6794 flexible mechanism for handling and presenting
6795 documentation. The recommended practice is for every Debian
6796 package that provides online documentation (other than just
6797 manual pages) to register these documents with
6798 <package>doc-base</package> by installing a
6799 <package>doc-base</package> control file via the
6800 <prgn/install-docs/ script at installation time and
6801 de-register the manuals again when the package is removed.
6804 Please refer to the documentation that comes with the
6805 <package>doc-base</package> package for information and
6814 <heading>Files</heading>
6817 <heading>Binaries</heading>
6820 Two different packages must not install programs with
6821 different functionality but with the same filenames. (The
6822 case of two programs having the same functionality but
6823 different implementations is handled via "alternatives" or
6824 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6825 <ref id="conflicts"> respectively.) If this case happens,
6826 one of the programs must be renamed. The maintainers should
6827 report this to the <tt>debian-devel</tt> mailing list and
6828 try to find a consensus about which program will have to be
6829 renamed. If a consensus cannot be reached, <em>both</em>
6830 programs must be renamed.
6834 By default, when a package is being built, any binaries
6835 created should include debugging information, as well as
6836 being compiled with optimization. You should also turn on
6837 as many reasonable compilation warnings as possible; this
6838 makes life easier for porters, who can then look at build
6839 logs for possible problems. For the C programming language,
6840 this means the following compilation parameters should be
6842 <example compact="compact">
6844 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6846 INSTALL = install -s # (or use strip on the files in debian/tmp)
6851 Note that by default all installed binaries should be stripped,
6852 either by using the <tt>-s</tt> flag to
6853 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6854 the binaries after they have been copied into
6855 <file>debian/tmp</file> but before the tree is made into a
6860 Although binaries in the build tree should be compiled with
6861 debugging information by default, it can often be difficult to
6862 debug programs if they are also subjected to compiler
6863 optimization. For this reason, it is recommended to support the
6864 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6865 (see <ref id="debianrules-options">). This variable can contain
6866 several flags to change how a package is compiled and built.
6870 It is up to the package maintainer to decide what
6871 compilation options are best for the package. Certain
6872 binaries (such as computationally-intensive programs) will
6873 function better with certain flags (<tt>-O3</tt>, for
6874 example); feel free to use them. Please use good judgment
6875 here. Don't use flags for the sake of it; only use them
6876 if there is good reason to do so. Feel free to override
6877 the upstream author's ideas about which compilation
6878 options are best: they are often inappropriate for our
6884 <sect id="libraries">
6885 <heading>Libraries</heading>
6888 If the package is <strong>architecture: any</strong>, then
6889 the shared library compilation and linking flags must have
6890 <tt>-fPIC</tt>, or the package shall not build on some of
6891 the supported architectures<footnote>
6893 If you are using GCC, <tt>-fPIC</tt> produces code with
6894 relocatable position independent code, which is required for
6895 most architectures to create a shared library, with i386 and
6896 perhaps some others where non position independent code is
6897 permitted in a shared library.
6900 Position independent code may have a performance penalty,
6901 especially on <tt>i386</tt>. However, in most cases the
6902 speed penalty must be measured against the memory wasted on
6903 the few architectures where non position independent code is
6906 </footnote>. Any exception to this rule must be discussed on
6907 the mailing list <em>debian-devel@lists.debian.org</em>, and
6908 a rough consensus obtained. The reasons for not compiling
6909 with <tt>-fPIC</tt> flag must be recorded in the file
6910 <tt>README.Debian</tt>, and care must be taken to either
6911 restrict the architecture or arrange for <tt>-fPIC</tt> to
6912 be used on architectures where it is required.<footnote>
6914 Some of the reasons why this might be required is if the
6915 library contains hand crafted assembly code that is not
6916 relocatable, the speed penalty is excessive for compute
6917 intensive libs, and similar reasons.
6922 As to the static libraries, the common case is not to have
6923 relocatable code, since there is no benefit, unless in specific
6924 cases; therefore the static version must not be compiled
6925 with the <tt>-fPIC</tt> flag. Any exception to this rule
6926 should be discussed on the mailing list
6927 <em>debian-devel@lists.debian.org</em>, and the reasons for
6928 compiling with the <tt>-fPIC</tt> flag must be recorded in
6929 the file <tt>README.Debian</tt>. <footnote>
6931 Some of the reasons for linking static libraries with
6932 the <tt>-fPIC</tt> flag are if, for example, one needs a
6933 Perl API for a library that is under rapid development,
6934 and has an unstable API, so shared libraries are
6935 pointless at this phase of the library's development. In
6936 that case, since Perl needs a library with relocatable
6937 code, it may make sense to create a static library with
6938 relocatable code. Another reason cited is if you are
6939 distilling various libraries into a common shared
6940 library, like <tt>mklibs</tt> does in the Debian
6946 In other words, if both a shared and a static library is
6947 being built, each source unit (<tt>*.c</tt>, for example,
6948 for C files) will need to be compiled twice, for the normal
6952 You must specify the gcc option <tt>-D_REENTRANT</tt>
6953 when building a library (either static or shared) to make
6954 the library compatible with LinuxThreads.
6958 Although not enforced by the build tools, shared libraries
6959 must be linked against all libraries that they use symbols from
6960 in the same way that binaries are. This ensures the correct
6961 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6962 system and guarantees that all libraries can be safely opened
6963 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6964 option <tt>-Wl,-z,defs</tt> when building a shared library.
6965 Since this option enforces symbol resolution at build time,
6966 a missing library reference will be caught early as a fatal
6971 All installed shared libraries should be stripped with
6972 <example compact="compact">
6973 strip --strip-unneeded <var>your-lib</var>
6975 (The option <tt>--strip-unneeded</tt> makes
6976 <prgn>strip</prgn> remove only the symbols which aren't
6977 needed for relocation processing.) Shared libraries can
6978 function perfectly well when stripped, since the symbols for
6979 dynamic linking are in a separate part of the ELF object
6981 You might also want to use the options
6982 <tt>--remove-section=.comment</tt> and
6983 <tt>--remove-section=.note</tt> on both shared libraries
6984 and executables, and <tt>--strip-debug</tt> on static
6990 Note that under some circumstances it may be useful to
6991 install a shared library unstripped, for example when
6992 building a separate package to support debugging.
6996 Shared object files (often <file>.so</file> files) that are not
6997 public libraries, that is, they are not meant to be linked
6998 to by third party executables (binaries of other packages),
6999 should be installed in subdirectories of the
7000 <file>/usr/lib</file> directory. Such files are exempt from the
7001 rules that govern ordinary shared libraries, except that
7002 they must not be installed executable and should be
7004 A common example are the so-called "plug-ins",
7005 internal shared objects that are dynamically loaded by
7006 programs using <manref name="dlopen" section="3">.
7011 An ever increasing number of packages are using
7012 <prgn>libtool</prgn> to do their linking. The latest GNU
7013 libtools (>= 1.3a) can take advantage of the metadata in the
7014 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7015 files). The main advantage of <prgn>libtool</prgn>'s
7016 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7017 store and subsequently access metadata with respect to the
7018 libraries it builds. <prgn>libtool</prgn> will search for
7019 those files, which contain a lot of useful information about
7020 a library (such as library dependency information for static
7021 linking). Also, they're <em>essential</em> for programs
7022 using <tt>libltdl</tt>.<footnote>
7023 Although <prgn>libtool</prgn> is fully capable of
7024 linking against shared libraries which don't have
7025 <tt>.la</tt> files, as it is a mere shell script it can
7026 add considerably to the build time of a
7027 <prgn>libtool</prgn>-using package if that shell script
7028 has to derive all this information from first principles
7029 for each library every time it is linked. With the
7030 advent of <prgn>libtool</prgn> version 1.4 (and to a
7031 lesser extent <prgn>libtool</prgn> version 1.3), the
7032 <file>.la</file> files also store information about
7033 inter-library dependencies which cannot necessarily be
7034 derived after the <file>.la</file> file is deleted.
7039 Packages that use <prgn>libtool</prgn> to create shared
7040 libraries should include the <file>.la</file> files in the
7041 <tt>-dev</tt> package, unless the package relies on
7042 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7043 the <tt>.la</tt> files must go in the run-time library
7048 You must make sure that you use only released versions of
7049 shared libraries to build your packages; otherwise other
7050 users will not be able to run your binaries
7051 properly. Producing source packages that depend on
7052 unreleased compilers is also usually a bad
7059 <heading>Shared libraries</heading>
7061 This section has moved to <ref id="sharedlibs">.
7067 <heading>Scripts</heading>
7070 All command scripts, including the package maintainer
7071 scripts inside the package and used by <prgn>dpkg</prgn>,
7072 should have a <tt>#!</tt> line naming the shell to be used
7077 In the case of Perl scripts this should be
7078 <tt>#!/usr/bin/perl</tt>.
7082 When scripts are installed into a directory in the system
7083 PATH, the script name should not include an extension such
7084 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7085 language currently used to implement it.
7088 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7089 should almost certainly start with <tt>set -e</tt> so that
7090 errors are detected. Every script should use
7091 <tt>set -e</tt> or check the exit status of <em>every</em>
7096 Scripts may assume that <file>/bin/sh</file> implements the
7097 SUSv3 Shell Command Language<footnote>
7098 Single UNIX Specification, version 3, which is also IEEE
7099 1003.1-2004 (POSIX), and is available on the World Wide Web
7100 from <url id="http://www.unix.org/version3/online.html"
7101 name="The Open Group"> after free
7102 registration.</footnote>
7103 plus the following additional features not mandated by
7105 These features are in widespread use in the Linux community
7106 and are implemented in all of bash, dash, and ksh, the most
7107 common shells users may wish to use as <file>/bin/sh</file>.
7110 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7111 must not generate a newline.</item>
7112 <item><tt>test</tt>, if implemented as a shell built-in, must
7113 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7115 <item><tt>local</tt> to create a scoped variable must be
7116 supported, including listing multiple variables in a single
7117 local command and assigning a value to a variable at the
7118 same time as localizing it. <tt>local</tt> may or
7119 may not preserve the variable value from an outer scope if
7120 no assignment is present. Uses such as:
7124 # ... use a, b, c, d ...
7127 must be supported and must set the value of <tt>c</tt> to
7131 If a shell script requires non-SUSv3 features from the shell
7132 interpreter other than those listed above, the appropriate shell
7133 must be specified in the first line of the script (e.g.,
7134 <tt>#!/bin/bash</tt>) and the package must depend on the package
7135 providing the shell (unless the shell package is marked
7136 "Essential", as in the case of <prgn>bash</prgn>).
7140 You may wish to restrict your script to SUSv3 features plus the
7141 above set when possible so that it may use <file>/bin/sh</file>
7142 as its interpreter. If your script works with <prgn>dash</prgn>
7143 (originally called <prgn>ash</prgn>), it probably complies with
7144 the above requirements, but if you are in doubt, use
7145 <file>/bin/bash</file>.
7149 Perl scripts should check for errors when making any
7150 system calls, including <tt>open</tt>, <tt>print</tt>,
7151 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7155 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7156 scripting languages. See <em>Csh Programming Considered
7157 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7158 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7159 If an upstream package comes with <prgn>csh</prgn> scripts
7160 then you must make sure that they start with
7161 <tt>#!/bin/csh</tt> and make your package depend on the
7162 <prgn>c-shell</prgn> virtual package.
7166 Any scripts which create files in world-writeable
7167 directories (e.g., in <file>/tmp</file>) must use a
7168 mechanism which will fail atomically if a file with the same
7169 name already exists.
7173 The Debian base system provides the <prgn>tempfile</prgn>
7174 and <prgn>mktemp</prgn> utilities for use by scripts for
7181 <heading>Symbolic links</heading>
7184 In general, symbolic links within a top-level directory
7185 should be relative, and symbolic links pointing from one
7186 top-level directory into another should be absolute. (A
7187 top-level directory is a sub-directory of the root
7188 directory <file>/</file>.)
7192 In addition, symbolic links should be specified as short as
7193 possible, i.e., link targets like <file>foo/../bar</file> are
7198 Note that when creating a relative link using
7199 <prgn>ln</prgn> it is not necessary for the target of the
7200 link to exist relative to the working directory you're
7201 running <prgn>ln</prgn> from, nor is it necessary to change
7202 directory to the directory where the link is to be made.
7203 Simply include the string that should appear as the target
7204 of the link (this will be a pathname relative to the
7205 directory in which the link resides) as the first argument
7210 For example, in your <prgn>Makefile</prgn> or
7211 <file>debian/rules</file>, you can do things like:
7212 <example compact="compact">
7213 ln -fs gcc $(prefix)/bin/cc
7214 ln -fs gcc debian/tmp/usr/bin/cc
7215 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7216 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7221 A symbolic link pointing to a compressed file should always
7222 have the same file extension as the referenced file. (For
7223 example, if a file <file>foo.gz</file> is referenced by a
7224 symbolic link, the filename of the link has to end with
7225 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7230 <heading>Device files</heading>
7233 Packages must not include device files in the package file
7238 If a package needs any special device files that are not
7239 included in the base system, it must call
7240 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7241 after notifying the user<footnote>
7242 This notification could be done via a (low-priority)
7243 debconf message, or an echo (printf) statement.
7248 Packages must not remove any device files in the
7249 <prgn>postrm</prgn> or any other script. This is left to the
7250 system administrator.
7254 Debian uses the serial devices
7255 <file>/dev/ttyS*</file>. Programs using the old
7256 <file>/dev/cu*</file> devices should be changed to use
7257 <file>/dev/ttyS*</file>.
7261 <sect id="config-files">
7262 <heading>Configuration files</heading>
7265 <heading>Definitions</heading>
7269 <tag>configuration file</tag>
7271 A file that affects the operation of a program, or
7272 provides site- or host-specific information, or
7273 otherwise customizes the behavior of a program.
7274 Typically, configuration files are intended to be
7275 modified by the system administrator (if needed or
7276 desired) to conform to local policy or to provide
7277 more useful site-specific behavior.
7280 <tag><tt>conffile</tt></tag>
7282 A file listed in a package's <tt>conffiles</tt>
7283 file, and is treated specially by <prgn>dpkg</prgn>
7284 (see <ref id="configdetails">).
7290 The distinction between these two is important; they are
7291 not interchangeable concepts. Almost all
7292 <tt>conffile</tt>s are configuration files, but many
7293 configuration files are not <tt>conffiles</tt>.
7297 As noted elsewhere, <file>/etc/init.d</file> scripts,
7298 <file>/etc/default</file> files, scripts installed in
7299 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7300 configuration installed in <file>/etc/cron.d</file> must be
7301 treated as configuration files. In general, any script that
7302 embeds configuration information is de-facto a configuration
7303 file and should be treated as such.
7308 <heading>Location</heading>
7311 Any configuration files created or used by your package
7312 must reside in <file>/etc</file>. If there are several,
7313 consider creating a subdirectory of <file>/etc</file>
7314 named after your package.
7318 If your package creates or uses configuration files
7319 outside of <file>/etc</file>, and it is not feasible to modify
7320 the package to use <file>/etc</file> directly, put the files
7321 in <file>/etc</file> and create symbolic links to those files
7322 from the location that the package requires.
7327 <heading>Behavior</heading>
7330 Configuration file handling must conform to the following
7332 <list compact="compact">
7334 local changes must be preserved during a package
7338 configuration files must be preserved when the
7339 package is removed, and only deleted when the
7346 The easy way to achieve this behavior is to make the
7347 configuration file a <tt>conffile</tt>. This is
7348 appropriate only if it is possible to distribute a default
7349 version that will work for most installations, although
7350 some system administrators may choose to modify it. This
7351 implies that the default version will be part of the
7352 package distribution, and must not be modified by the
7353 maintainer scripts during installation (or at any other
7358 In order to ensure that local changes are preserved
7359 correctly, no package may contain or make hard links to
7360 conffiles.<footnote>
7361 Rationale: There are two problems with hard links.
7362 The first is that some editors break the link while
7363 editing one of the files, so that the two files may
7364 unwittingly become unlinked and different. The second
7365 is that <prgn>dpkg</prgn> might break the hard link
7366 while upgrading <tt>conffile</tt>s.
7371 The other way to do it is via the maintainer scripts. In
7372 this case, the configuration file must not be listed as a
7373 <tt>conffile</tt> and must not be part of the package
7374 distribution. If the existence of a file is required for
7375 the package to be sensibly configured it is the
7376 responsibility of the package maintainer to provide
7377 maintainer scripts which correctly create, update and
7378 maintain the file and remove it on purge. (See <ref
7379 id="maintainerscripts"> for more information.) These
7380 scripts must be idempotent (i.e., must work correctly if
7381 <prgn>dpkg</prgn> needs to re-run them due to errors
7382 during installation or removal), must cope with all the
7383 variety of ways <prgn>dpkg</prgn> can call maintainer
7384 scripts, must not overwrite or otherwise mangle the user's
7385 configuration without asking, must not ask unnecessary
7386 questions (particularly during upgrades), and must
7387 otherwise be good citizens.
7391 The scripts are not required to configure every possible
7392 option for the package, but only those necessary to get
7393 the package running on a given system. Ideally the
7394 sysadmin should not have to do any configuration other
7395 than that done (semi-)automatically by the
7396 <prgn>postinst</prgn> script.
7400 A common practice is to create a script called
7401 <file><var>package</var>-configure</file> and have the
7402 package's <prgn>postinst</prgn> call it if and only if the
7403 configuration file does not already exist. In certain
7404 cases it is useful for there to be an example or template
7405 file which the maintainer scripts use. Such files should
7406 be in <file>/usr/share/<var>package</var></file> or
7407 <file>/usr/lib/<var>package</var></file> (depending on whether
7408 they are architecture-independent or not). There should
7409 be symbolic links to them from
7410 <file>/usr/share/doc/<var>package</var>/examples</file> if
7411 they are examples, and should be perfectly ordinary
7412 <prgn>dpkg</prgn>-handled files (<em>not</em>
7413 configuration files).
7417 These two styles of configuration file handling must
7418 not be mixed, for that way lies madness:
7419 <prgn>dpkg</prgn> will ask about overwriting the file
7420 every time the package is upgraded.
7425 <heading>Sharing configuration files</heading>
7428 Packages which specify the same file as a
7429 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7430 with each other. (This is an instance of the general rule
7431 about not sharing files. Note that neither alternatives
7432 nor diversions are likely to be appropriate in this case;
7433 in particular, <prgn>dpkg</prgn> does not handle diverted
7434 <tt>conffile</tt>s well.)
7438 The maintainer scripts must not alter a <tt>conffile</tt>
7439 of <em>any</em> package, including the one the scripts
7444 If two or more packages use the same configuration file
7445 and it is reasonable for both to be installed at the same
7446 time, one of these packages must be defined as
7447 <em>owner</em> of the configuration file, i.e., it will be
7448 the package which handles that file as a configuration
7449 file. Other packages that use the configuration file must
7450 depend on the owning package if they require the
7451 configuration file to operate. If the other package will
7452 use the configuration file if present, but is capable of
7453 operating without it, no dependency need be declared.
7457 If it is desirable for two or more related packages to
7458 share a configuration file <em>and</em> for all of the
7459 related packages to be able to modify that configuration
7460 file, then the following should be done:
7461 <enumlist compact="compact">
7463 One of the related packages (the "owning" package)
7464 will manage the configuration file with maintainer
7465 scripts as described in the previous section.
7468 The owning package should also provide a program
7469 that the other packages may use to modify the
7473 The related packages must use the provided program
7474 to make any desired modifications to the
7475 configuration file. They should either depend on
7476 the core package to guarantee that the configuration
7477 modifier program is available or accept gracefully
7478 that they cannot modify the configuration file if it
7479 is not. (This is in addition to the fact that the
7480 configuration file may not even be present in the
7487 Sometimes it's appropriate to create a new package which
7488 provides the basic infrastructure for the other packages
7489 and which manages the shared configuration files. (The
7490 <tt>sgml-base</tt> package is a good example.)
7495 <heading>User configuration files ("dotfiles")</heading>
7498 The files in <file>/etc/skel</file> will automatically be
7499 copied into new user accounts by <prgn>adduser</prgn>.
7500 No other program should reference the files in
7501 <file>/etc/skel</file>.
7505 Therefore, if a program needs a dotfile to exist in
7506 advance in <file>$HOME</file> to work sensibly, that dotfile
7507 should be installed in <file>/etc/skel</file> and treated as a
7512 However, programs that require dotfiles in order to
7513 operate sensibly are a bad thing, unless they do create
7514 the dotfiles themselves automatically.
7518 Furthermore, programs should be configured by the Debian
7519 default installation to behave as closely to the upstream
7520 default behavior as possible.
7524 Therefore, if a program in a Debian package needs to be
7525 configured in some way in order to operate sensibly, that
7526 should be done using a site-wide configuration file placed
7527 in <file>/etc</file>. Only if the program doesn't support a
7528 site-wide default configuration and the package maintainer
7529 doesn't have time to add it may a default per-user file be
7530 placed in <file>/etc/skel</file>.
7534 <file>/etc/skel</file> should be as empty as we can make it.
7535 This is particularly true because there is no easy (or
7536 necessarily desirable) mechanism for ensuring that the
7537 appropriate dotfiles are copied into the accounts of
7538 existing users when a package is installed.
7544 <heading>Log files</heading>
7546 Log files should usually be named
7547 <file>/var/log/<var>package</var>.log</file>. If you have many
7548 log files, or need a separate directory for permission
7549 reasons (<file>/var/log</file> is writable only by
7550 <file>root</file>), you should usually create a directory named
7551 <file>/var/log/<var>package</var></file> and place your log
7556 Log files must be rotated occasionally so that they don't
7557 grow indefinitely; the best way to do this is to drop a log
7558 rotation configuration file into the directory
7559 <file>/etc/logrotate.d</file> and use the facilities provided by
7560 logrotate.<footnote>
7562 The traditional approach to log files has been to set up
7563 <em>ad hoc</em> log rotation schemes using simple shell
7564 scripts and cron. While this approach is highly
7565 customizable, it requires quite a lot of sysadmin work.
7566 Even though the original Debian system helped a little
7567 by automatically installing a system which can be used
7568 as a template, this was deemed not enough.
7572 The use of <prgn>logrotate</prgn>, a program developed
7573 by Red Hat, is better, as it centralizes log management.
7574 It has both a configuration file
7575 (<file>/etc/logrotate.conf</file>) and a directory where
7576 packages can drop their individual log rotation
7577 configurations (<file>/etc/logrotate.d</file>).
7580 Here is a good example for a logrotate config
7581 file (for more information see <manref name="logrotate"
7583 <example compact="compact">
7584 /var/log/foo/*.log {
7589 /etc/init.d/foo force-reload
7593 This rotates all files under <file>/var/log/foo</file>, saves 12
7594 compressed generations, and forces the daemon to reload its
7595 configuration information after the log rotation.
7599 Log files should be removed when the package is
7600 purged (but not when it is only removed). This should be
7601 done by the <prgn>postrm</prgn> script when it is called
7602 with the argument <tt>purge</tt> (see <ref
7603 id="removedetails">).
7608 <heading>Permissions and owners</heading>
7611 The rules in this section are guidelines for general use.
7612 If necessary you may deviate from the details below.
7613 However, if you do so you must make sure that what is done
7614 is secure and you should try to be as consistent as possible
7615 with the rest of the system. You should probably also
7616 discuss it on <prgn>debian-devel</prgn> first.
7620 Files should be owned by <tt>root:root</tt>, and made
7621 writable only by the owner and universally readable (and
7622 executable, if appropriate), that is mode 644 or 755.
7626 Directories should be mode 755 or (for group-writability)
7627 mode 2775. The ownership of the directory should be
7628 consistent with its mode: if a directory is mode 2775, it
7629 should be owned by the group that needs write access to
7632 When a package is upgraded, and the owner or permissions
7633 of a file included in the package has changed, dpkg
7634 arranges for the ownership and permissions to be
7635 correctly set upon installation. However, this does not
7636 extend to directories; the permissions and ownership of
7637 directories already on the system does not change on
7638 install or upgrade of packages. This makes sense, since
7639 otherwise common directories like <tt>/usr</tt> would
7640 always be in flux. To correctly change permissions of a
7641 directory the package owns, explicit action is required,
7642 usually in the <tt>postinst</tt> script. Care must be
7643 taken to handle downgrades as well, in that case.
7650 Setuid and setgid executables should be mode 4755 or 2755
7651 respectively, and owned by the appropriate user or group.
7652 They should not be made unreadable (modes like 4711 or
7653 2711 or even 4111); doing so achieves no extra security,
7654 because anyone can find the binary in the freely available
7655 Debian package; it is merely inconvenient. For the same
7656 reason you should not restrict read or execute permissions
7657 on non-set-id executables.
7661 Some setuid programs need to be restricted to particular
7662 sets of users, using file permissions. In this case they
7663 should be owned by the uid to which they are set-id, and by
7664 the group which should be allowed to execute them. They
7665 should have mode 4754; again there is no point in making
7666 them unreadable to those users who must not be allowed to
7671 It is possible to arrange that the system administrator can
7672 reconfigure the package to correspond to their local
7673 security policy by changing the permissions on a binary:
7674 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7675 described below.<footnote>
7676 Ordinary files installed by <prgn>dpkg</prgn> (as
7677 opposed to <tt>conffile</tt>s and other similar objects)
7678 normally have their permissions reset to the distributed
7679 permissions when the package is reinstalled. However,
7680 the use of <prgn>dpkg-statoverride</prgn> overrides this
7681 default behavior. If you use this method, you should
7682 remember to describe <prgn>dpkg-statoverride</prgn> in
7683 the package documentation; being a relatively new
7684 addition to Debian, it is probably not yet well-known.
7686 Another method you should consider is to create a group for
7687 people allowed to use the program(s) and make any setuid
7688 executables executable only by that group.
7692 If you need to create a new user or group for your package
7693 there are two possibilities. Firstly, you may need to
7694 make some files in the binary package be owned by this
7695 user or group, or you may need to compile the user or
7696 group id (rather than just the name) into the binary
7697 (though this latter should be avoided if possible, as in
7698 this case you need a statically allocated id).</p>
7701 If you need a statically allocated id, you must ask for a
7702 user or group id from the <tt>base-passwd</tt> maintainer,
7703 and must not release the package until you have been
7704 allocated one. Once you have been allocated one you must
7705 either make the package depend on a version of the
7706 <tt>base-passwd</tt> package with the id present in
7707 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7708 your package to create the user or group itself with the
7709 correct id (using <tt>adduser</tt>) in its
7710 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7711 the <prgn>postinst</prgn> is to be preferred if it is
7712 possible, otherwise a pre-dependency will be needed on the
7713 <tt>adduser</tt> package.)
7717 On the other hand, the program might be able to determine
7718 the uid or gid from the user or group name at runtime, so
7719 that a dynamically allocated id can be used. In this case
7720 you should choose an appropriate user or group name,
7721 discussing this on <prgn>debian-devel</prgn> and checking
7722 with the <package/base-passwd/ maintainer that it is unique and that
7723 they do not wish you to use a statically allocated id
7724 instead. When this has been checked you must arrange for
7725 your package to create the user or group if necessary using
7726 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7727 <prgn>postinst</prgn> script (again, the latter is to be
7728 preferred if it is possible).
7732 Note that changing the numeric value of an id associated
7733 with a name is very difficult, and involves searching the
7734 file system for all appropriate files. You need to think
7735 carefully whether a static or dynamic id is required, since
7736 changing your mind later will cause problems.
7739 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7741 This section is not intended as policy, but as a
7742 description of the use of <prgn>dpkg-statoverride</prgn>.
7746 If a system administrator wishes to have a file (or
7747 directory or other such thing) installed with owner and
7748 permissions different from those in the distributed Debian
7749 package, they can use the <prgn>dpkg-statoverride</prgn>
7750 program to instruct <prgn>dpkg</prgn> to use the different
7751 settings every time the file is installed. Thus the
7752 package maintainer should distribute the files with their
7753 normal permissions, and leave it for the system
7754 administrator to make any desired changes. For example, a
7755 daemon which is normally required to be setuid root, but
7756 in certain situations could be used without being setuid,
7757 should be installed setuid in the <tt>.deb</tt>. Then the
7758 local system administrator can change this if they wish.
7759 If there are two standard ways of doing it, the package
7760 maintainer can use <tt>debconf</tt> to find out the
7761 preference, and call <prgn>dpkg-statoverride</prgn> in the
7762 maintainer script if necessary to accommodate the system
7763 administrator's choice. Care must be taken during
7764 upgrades to not override an existing setting.
7768 Given the above, <prgn>dpkg-statoverride</prgn> is
7769 essentially a tool for system administrators and would not
7770 normally be needed in the maintainer scripts. There is
7771 one type of situation, though, where calls to
7772 <prgn>dpkg-statoverride</prgn> would be needed in the
7773 maintainer scripts, and that involves packages which use
7774 dynamically allocated user or group ids. In such a
7775 situation, something like the following idiom can be very
7776 helpful in the package's <prgn>postinst</prgn>, where
7777 <tt>sysuser</tt> is a dynamically allocated id:
7779 for i in /usr/bin/foo /usr/sbin/bar
7781 # only do something when no setting exists
7782 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7784 #include: debconf processing, question about foo and bar
7785 if [ "$RET" = "true" ] ; then
7786 dpkg-statoverride --update --add sysuser root 4755 $i
7791 The corresponding code to remove the override when the package
7794 for i in /usr/bin/foo /usr/sbin/bar
7796 if dpkg-statoverride --list $i >/dev/null 2>&1
7798 dpkg-statoverride --remove $i
7808 <chapt id="customized-programs">
7809 <heading>Customized programs</heading>
7811 <sect id="arch-spec">
7812 <heading>Architecture specification strings</heading>
7815 If a program needs to specify an <em>architecture specification
7816 string</em> in some place, it should select one of the
7817 strings provided by <tt>dpkg-architecture -L</tt>. The
7818 strings are in the format
7819 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7820 is sometimes elided, as when the OS is Linux.<footnote>
7821 <p>Currently, the strings are:
7822 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7823 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7824 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7825 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7826 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7827 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7828 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7829 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7830 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7831 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7832 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7833 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7834 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7835 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7836 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7837 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7838 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7839 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7840 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7841 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7842 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7843 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7844 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7845 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7846 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7847 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7848 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7849 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7850 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7851 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7852 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7853 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7854 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7855 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7856 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7857 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7858 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7864 Note that we don't want to use
7865 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7866 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7867 since this would make our programs incompatible with other
7868 Linux distributions. We also don't use something like
7869 <tt><var>arch</var>-unknown-linux</tt>, since the
7870 <tt>unknown</tt> does not look very good.
7875 <heading>Daemons</heading>
7878 The configuration files <file>/etc/services</file>,
7879 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7880 by the <prgn>netbase</prgn> package and must not be modified
7885 If a package requires a new entry in one of these files, the
7886 maintainer should get in contact with the
7887 <prgn>netbase</prgn> maintainer, who will add the entries
7888 and release a new version of the <prgn>netbase</prgn>
7893 The configuration file <file>/etc/inetd.conf</file> must not be
7894 modified by the package's scripts except via the
7895 <prgn>update-inetd</prgn> script or the
7896 <file>DebianNet.pm</file> Perl module. See their documentation
7897 for details on how to add entries.
7901 If a package wants to install an example entry into
7902 <file>/etc/inetd.conf</file>, the entry must be preceded with
7903 exactly one hash character (<tt>#</tt>). Such lines are
7904 treated as "commented out by user" by the
7905 <prgn>update-inetd</prgn> script and are not changed or
7906 activated during package updates.
7911 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7915 Some programs need to create pseudo-ttys. This should be done
7916 using Unix98 ptys if the C library supports it. The resulting
7917 program must not be installed setuid root, unless that
7918 is required for other functionality.
7922 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7923 <file>/var/log/lastlog</file> must be installed writable by
7924 group <tt>utmp</tt>. Programs which need to modify those
7925 files must be installed setgid <tt>utmp</tt>.
7930 <heading>Editors and pagers</heading>
7933 Some programs have the ability to launch an editor or pager
7934 program to edit or display a text document. Since there are
7935 lots of different editors and pagers available in the Debian
7936 distribution, the system administrator and each user should
7937 have the possibility to choose their preferred editor and
7942 In addition, every program should choose a good default
7943 editor/pager if none is selected by the user or system
7948 Thus, every program that launches an editor or pager must
7949 use the EDITOR or PAGER environment variable to determine
7950 the editor or pager the user wishes to use. If these
7951 variables are not set, the programs <file>/usr/bin/editor</file>
7952 and <file>/usr/bin/pager</file> should be used, respectively.
7956 These two files are managed through the <prgn>dpkg</prgn>
7957 "alternatives" mechanism. Thus every package providing an
7958 editor or pager must call the
7959 <prgn>update-alternatives</prgn> script to register these
7964 If it is very hard to adapt a program to make use of the
7965 EDITOR or PAGER variables, that program may be configured to
7966 use <file>/usr/bin/sensible-editor</file> and
7967 <file>/usr/bin/sensible-pager</file> as the editor or pager
7968 program respectively. These are two scripts provided in the
7969 <package>sensible-utils</package> package that check the EDITOR
7970 and PAGER variables and launch the appropriate program, and fall
7971 back to <file>/usr/bin/editor</file>
7972 and <file>/usr/bin/pager</file> if the variable is not set.
7976 A program may also use the VISUAL environment variable to
7977 determine the user's choice of editor. If it exists, it
7978 should take precedence over EDITOR. This is in fact what
7979 <file>/usr/bin/sensible-editor</file> does.
7983 It is not required for a package to depend on
7984 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7985 package to provide such virtual packages.<footnote>
7986 The Debian base system already provides an editor and a
7992 <sect id="web-appl">
7993 <heading>Web servers and applications</heading>
7996 This section describes the locations and URLs that should
7997 be used by all web servers and web applications in the
8004 Cgi-bin executable files are installed in the
8006 <example compact="compact">
8007 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8009 and should be referred to as
8010 <example compact="compact">
8011 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8017 <p>Access to HTML documents</p>
8020 HTML documents for a package are stored in
8021 <file>/usr/share/doc/<var>package</var></file>
8022 and can be referred to as
8023 <example compact="compact">
8024 http://localhost/doc/<var>package</var>/<var>filename</var>
8029 The web server should restrict access to the document
8030 tree so that only clients on the same host can read
8031 the documents. If the web server does not support such
8032 access controls, then it should not provide access at
8033 all, or ask about providing access during installation.
8038 <p>Access to images</p>
8040 It is recommended that images for a package be stored
8041 in <tt>/usr/share/images/<var>package</var></tt> and
8042 may be referred to through an alias <tt>/images/</tt>
8045 http://localhost/images/<package>/<filename>
8052 <p>Web Document Root</p>
8055 Web Applications should try to avoid storing files in
8056 the Web Document Root. Instead they should use the
8057 /usr/share/doc/<var>package</var> directory for
8058 documents and register the Web Application via the
8059 <package>doc-base</package> package. If access to the
8060 web document root is unavoidable then use
8061 <example compact="compact">
8064 as the Document Root. This might be just a symbolic
8065 link to the location where the system administrator
8066 has put the real document root.
8069 <item><p>Providing httpd and/or httpd-cgi</p>
8071 All web servers should provide the virtual package
8072 <tt>httpd</tt>. If a web server has CGI support it should
8073 provide <tt>httpd-cgi</tt> additionally.
8076 All web applications which do not contain CGI scripts should
8077 depend on <tt>httpd</tt>, all those web applications which
8078 <tt>do</tt> contain CGI scripts, should depend on
8086 <sect id="mail-transport-agents">
8087 <heading>Mail transport, delivery and user agents</heading>
8090 Debian packages which process electronic mail, whether mail
8091 user agents (MUAs) or mail transport agents (MTAs), must
8092 ensure that they are compatible with the configuration
8093 decisions below. Failure to do this may result in lost
8094 mail, broken <tt>From:</tt> lines, and other serious brain
8099 The mail spool is <file>/var/mail</file> and the interface to
8100 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8101 the FHS). On older systems, the mail spool may be
8102 physically located in <file>/var/spool/mail</file>, but all
8103 access to the mail spool should be via the
8104 <file>/var/mail</file> symlink. The mail spool is part of the
8105 base system and not part of the MTA package.
8109 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8110 programs (such as IMAP daemons) must lock the mailbox in an
8111 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8112 be combined with dot locking. To avoid deadlocks, a program
8113 should use <tt>fcntl()</tt> first and dot locking after
8114 this, or alternatively implement the two locking methods in
8115 a non blocking way<footnote>
8116 If it is not possible to establish both locks, the
8117 system shouldn't wait for the second lock to be
8118 established, but remove the first lock, wait a (random)
8119 time, and start over locking again.
8120 </footnote>. Using the functions <tt>maillock</tt> and
8121 <tt>mailunlock</tt> provided by the
8122 <tt>liblockfile*</tt><footnote>
8123 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8124 to use these functions.
8125 </footnote> packages is the recommended way to realize this.
8129 Mailboxes are generally either mode 600 and owned by
8130 <var>user</var> or mode 660 and owned by
8131 <tt><var>user</var>:mail</tt><footnote>
8132 There are two traditional permission schemes for mail spools:
8133 mode 600 with all mail delivery done by processes running as
8134 the destination user, or mode 660 and owned by group mail with
8135 mail delivery done by a process running as a system user in
8136 group mail. Historically, Debian required mode 660 mail
8137 spools to enable the latter model, but that model has become
8138 increasingly uncommon and the principle of least privilege
8139 indicates that mail systems that use the first model should
8140 use permissions of 600. If delivery to programs is permitted,
8141 it's easier to keep the mail system secure if the delivery
8142 agent runs as the destination user. Debian Policy therefore
8143 permits either scheme.
8144 </footnote>. The local system administrator may choose a
8145 different permission scheme; packages should not make
8146 assumptions about the permission and ownership of mailboxes
8147 unless required (such as when creating a new mailbox). A MUA
8148 may remove a mailbox (unless it has nonstandard permissions) in
8149 which case the MTA or another MUA must recreate it if needed.
8153 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8154 be setgid mail to do the locking mentioned above (and
8155 must obviously avoid accessing other users' mailboxes
8156 using this privilege).</p>
8159 <file>/etc/aliases</file> is the source file for the system mail
8160 aliases (e.g., postmaster, usenet, etc.), it is the one
8161 which the sysadmin and <prgn>postinst</prgn> scripts may
8162 edit. After <file>/etc/aliases</file> is edited the program or
8163 human editing it must call <prgn>newaliases</prgn>. All MTA
8164 packages must come with a <prgn>newaliases</prgn> program,
8165 even if it does nothing, but older MTA packages did not do
8166 this so programs should not fail if <prgn>newaliases</prgn>
8167 cannot be found. Note that because of this, all MTA
8168 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8169 <tt>Replaces: mail-transport-agent</tt> control file
8174 The convention of writing <tt>forward to
8175 <var>address</var></tt> in the mailbox itself is not
8176 supported. Use a <tt>.forward</tt> file instead.</p>
8179 The <prgn>rmail</prgn> program used by UUCP
8180 for incoming mail should be <file>/usr/sbin/rmail</file>.
8181 Likewise, <prgn>rsmtp</prgn>, for receiving
8182 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8186 If your package needs to know what hostname to use on (for
8187 example) outgoing news and mail messages which are generated
8188 locally, you should use the file <file>/etc/mailname</file>. It
8189 will contain the portion after the username and <tt>@</tt>
8190 (at) sign for email addresses of users on the machine
8191 (followed by a newline).
8195 Such a package should check for the existence of this file
8196 when it is being configured. If it exists, it should be
8197 used without comment, although an MTA's configuration script
8198 may wish to prompt the user even if it finds that this file
8199 exists. If the file does not exist, the package should
8200 prompt the user for the value (preferably using
8201 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8202 as well as using it in the package's configuration. The
8203 prompt should make it clear that the name will not just be
8204 used by that package. For example, in this situation the
8205 <tt>inn</tt> package could say something like:
8206 <example compact="compact">
8207 Please enter the "mail name" of your system. This is the
8208 hostname portion of the address to be shown on outgoing
8209 news and mail messages. The default is
8210 <var>syshostname</var>, your system's host name. Mail
8211 name ["<var>syshostname</var>"]:
8213 where <var>syshostname</var> is the output of <tt>hostname
8219 <heading>News system configuration</heading>
8222 All the configuration files related to the NNTP (news)
8223 servers and clients should be located under
8224 <file>/etc/news</file>.</p>
8227 There are some configuration issues that apply to a number
8228 of news clients and server packages on the machine. These
8232 <tag><file>/etc/news/organization</file></tag>
8234 A string which should appear as the
8235 organization header for all messages posted
8236 by NNTP clients on the machine
8239 <tag><file>/etc/news/server</file></tag>
8241 Contains the FQDN of the upstream NNTP
8242 server, or localhost if the local machine is
8247 Other global files may be added as required for cross-package news
8254 <heading>Programs for the X Window System</heading>
8257 <heading>Providing X support and package priorities</heading>
8260 Programs that can be configured with support for the X
8261 Window System must be configured to do so and must declare
8262 any package dependencies necessary to satisfy their
8263 runtime requirements when using the X Window System. If
8264 such a package is of higher priority than the X packages
8265 on which it depends, it is required that either the
8266 X-specific components be split into a separate package, or
8267 that an alternative version of the package, which includes
8268 X support, be provided, or that the package's priority be
8274 <heading>Packages providing an X server</heading>
8277 Packages that provide an X server that, directly or
8278 indirectly, communicates with real input and display
8279 hardware should declare in their control data that they
8280 provide the virtual package <tt>xserver</tt>.<footnote>
8281 This implements current practice, and provides an
8282 actual policy for usage of the <tt>xserver</tt>
8283 virtual package which appears in the virtual packages
8284 list. In a nutshell, X servers that interface
8285 directly with the display and input hardware or via
8286 another subsystem (e.g., GGI) should provide
8287 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8288 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8294 <heading>Packages providing a terminal emulator</heading>
8297 Packages that provide a terminal emulator for the X Window
8298 System which meet the criteria listed below should declare
8299 in their control data that they provide the virtual
8300 package <tt>x-terminal-emulator</tt>. They should also
8301 register themselves as an alternative for
8302 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8307 To be an <tt>x-terminal-emulator</tt>, a program must:
8308 <list compact="compact">
8310 Be able to emulate a DEC VT100 terminal, or a
8311 compatible terminal.
8315 Support the command-line option <tt>-e
8316 <var>command</var></tt>, which creates a new
8317 terminal window<footnote>
8318 "New terminal window" does not necessarily mean
8319 a new top-level X window directly parented by
8320 the window manager; it could, if the terminal
8321 emulator application were so coded, be a new
8322 "view" in a multiple-document interface (MDI).
8324 and runs the specified <var>command</var>,
8325 interpreting the entirety of the rest of the command
8326 line as a command to pass straight to exec, in the
8327 manner that <tt>xterm</tt> does.
8331 Support the command-line option <tt>-T
8332 <var>title</var></tt>, which creates a new terminal
8333 window with the window title <var>title</var>.
8340 <heading>Packages providing a window manager</heading>
8343 Packages that provide a window manager should declare in
8344 their control data that they provide the virtual package
8345 <tt>x-window-manager</tt>. They should also register
8346 themselves as an alternative for
8347 <file>/usr/bin/x-window-manager</file>, with a priority
8348 calculated as follows:
8349 <list compact="compact">
8351 Start with a priority of 20.
8355 If the window manager supports the Debian menu
8356 system, add 20 points if this support is available
8357 in the package's default configuration (i.e., no
8358 configuration files belonging to the system or user
8359 have to be edited to activate the feature); if
8360 configuration files must be modified, add only 10
8366 If the window manager complies with <url
8367 id="http://www.freedesktop.org/Standards/wm-spec"
8368 name="The Window Manager Specification Project">,
8369 written by the <url id="http://www.freedesktop.org/"
8370 name="Free Desktop Group">, add 40 points.
8374 If the window manager permits the X session to be
8375 restarted using a <em>different</em> window manager
8376 (without killing the X server) in its default
8377 configuration, add 10 points; otherwise add none.
8384 <heading>Packages providing fonts</heading>
8387 Packages that provide fonts for the X Window
8389 For the purposes of Debian Policy, a "font for the X
8390 Window System" is one which is accessed via X protocol
8391 requests. Fonts for the Linux console, for PostScript
8392 renderer, or any other purpose, do not fit this
8393 definition. Any tool which makes such fonts available
8394 to the X Window System, however, must abide by this
8397 must do a number of things to ensure that they are both
8398 available without modification of the X or font server
8399 configuration, and that they do not corrupt files used by
8400 other font packages to register information about
8404 Fonts of any type supported by the X Window System
8405 must be in a separate binary package from any
8406 executables, libraries, or documentation (except
8407 that specific to the fonts shipped, such as their
8408 license information). If one or more of the fonts
8409 so packaged are necessary for proper operation of
8410 the package with which they are associated the font
8411 package may be Recommended; if the fonts merely
8412 provide an enhancement, a Suggests relationship may
8413 be used. Packages must not Depend on font
8415 This is because the X server may retrieve fonts
8416 from the local file system or over the network
8417 from an X font server; the Debian package system
8418 is empowered to deal only with the local
8424 BDF fonts must be converted to PCF fonts with the
8425 <prgn>bdftopcf</prgn> utility (available in the
8426 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8427 placed in a directory that corresponds to their
8429 <list compact="compact">
8431 100 dpi fonts must be placed in
8432 <file>/usr/share/fonts/X11/100dpi/</file>.
8436 75 dpi fonts must be placed in
8437 <file>/usr/share/fonts/X11/75dpi/</file>.
8441 Character-cell fonts, cursor fonts, and other
8442 low-resolution fonts must be placed in
8443 <file>/usr/share/fonts/X11/misc/</file>.
8449 Type 1 fonts must be placed in
8450 <file>/usr/share/fonts/X11/Type1/</file>. If font
8451 metric files are available, they must be placed here
8456 Subdirectories of <file>/usr/share/fonts/X11/</file>
8457 other than those listed above must be neither
8458 created nor used. (The <file>PEX</file>, <file>CID</file>,
8459 <file>Speedo</file>, and <file>cyrillic</file> directories
8460 are excepted for historical reasons, but installation of
8461 files into these directories remains discouraged.)
8465 Font packages may, instead of placing files directly
8466 in the X font directories listed above, provide
8467 symbolic links in that font directory pointing to
8468 the files' actual location in the filesystem. Such
8469 a location must comply with the FHS.
8473 Font packages should not contain both 75dpi and
8474 100dpi versions of a font. If both are available,
8475 they should be provided in separate binary packages
8476 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8477 the names of the packages containing the
8478 corresponding fonts.
8482 Fonts destined for the <file>misc</file> subdirectory
8483 should not be included in the same package as 75dpi
8484 or 100dpi fonts; instead, they should be provided in
8485 a separate package with <tt>-misc</tt> appended to
8490 Font packages must not provide the files
8491 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8492 <file>fonts.scale</file> in a font directory:
8495 <file>fonts.dir</file> files must not be provided at all.
8499 <file>fonts.alias</file> and <file>fonts.scale</file>
8500 files, if needed, should be provided in the
8502 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8503 where <var>fontdir</var> is the name of the
8505 <file>/usr/share/fonts/X11/</file> where the
8506 package's corresponding fonts are stored
8507 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8508 <var>package</var> is the name of the package
8509 that provides these fonts, and
8510 <var>extension</var> is either <tt>scale</tt>
8511 or <tt>alias</tt>, whichever corresponds to
8518 Font packages must declare a dependency on
8519 <tt>xfonts-utils</tt> in their control
8524 Font packages that provide one or more
8525 <file>fonts.scale</file> files as described above must
8526 invoke <prgn>update-fonts-scale</prgn> on each
8527 directory into which they installed fonts
8528 <em>before</em> invoking
8529 <prgn>update-fonts-dir</prgn> on that directory.
8530 This invocation must occur in both the
8531 <prgn>postinst</prgn> (for all arguments) and
8532 <prgn>postrm</prgn> (for all arguments except
8533 <tt>upgrade</tt>) scripts.
8537 Font packages that provide one or more
8538 <file>fonts.alias</file> files as described above must
8539 invoke <prgn>update-fonts-alias</prgn> on each
8540 directory into which they installed fonts. This
8541 invocation must occur in both the
8542 <prgn>postinst</prgn> (for all arguments) and
8543 <prgn>postrm</prgn> (for all arguments except
8544 <tt>upgrade</tt>) scripts.
8548 Font packages must invoke
8549 <prgn>update-fonts-dir</prgn> on each directory into
8550 which they installed fonts. This invocation must
8551 occur in both the <prgn>postinst</prgn> (for all
8552 arguments) and <prgn>postrm</prgn> (for all
8553 arguments except <tt>upgrade</tt>) scripts.
8557 Font packages must not provide alias names for the
8558 fonts they include which collide with alias names
8559 already in use by fonts already packaged.
8563 Font packages must not provide fonts with the same
8564 XLFD registry name as another font already packaged.
8570 <sect1 id="appdefaults">
8571 <heading>Application defaults files</heading>
8574 Application defaults files must be installed in the
8575 directory <file>/etc/X11/app-defaults/</file> (use of a
8576 localized subdirectory of <file>/etc/X11/</file> as described
8577 in the <em>X Toolkit Intrinsics - C Language
8578 Interface</em> manual is also permitted). They must be
8579 registered as <tt>conffile</tt>s or handled as
8580 configuration files.
8584 Customization of programs' X resources may also be
8585 supported with the provision of a file with the same name
8586 as that of the package placed in the
8587 <file>/etc/X11/Xresources/</file> directory, which must
8588 registered as a <tt>conffile</tt> or handled as a
8589 configuration file.<footnote>
8590 Note that this mechanism is not the same as using
8591 app-defaults; app-defaults are tied to the client
8592 binary on the local file system, whereas X resources
8593 are stored in the X server and affect all connecting
8600 <heading>Installation directory issues</heading>
8603 Historically, packages using the X Window System used a
8604 separate set of installation directories from other packages.
8605 This practice has been discontinued and packages using the X
8606 Window System should now generally be installed in the same
8607 directories as any other package. Specifically, packages must
8608 not install files under the <file>/usr/X11R6/</file> directory
8609 and the <file>/usr/X11R6/</file> directory hierarchy should be
8610 regarded as obsolete.
8614 Include files previously installed under
8615 <file>/usr/X11R6/include/X11/</file> should be installed into
8616 <file>/usr/include/X11/</file>. For files previously
8617 installed into subdirectories of
8618 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8619 determine if subdirectories of <file>/usr/lib/</file> and
8620 <file>/usr/share/</file> can be used. If not, a subdirectory
8621 of <file>/usr/lib/X11/</file> should be used.
8625 Configuration files for window, display, or session managers
8626 or other applications that are tightly integrated with the X
8627 Window System may be placed in a subdirectory
8628 of <file>/etc/X11/</file> corresponding to the package name.
8629 Other X Window System applications should use
8630 the <file>/etc/</file> directory unless otherwise mandated by
8631 policy (such as for <ref id="appdefaults">).
8636 <heading>The OSF/Motif and OpenMotif libraries</heading>
8639 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8640 OpenMotif libraries</em><footnote>
8641 OSF/Motif and OpenMotif are collectively referred to as
8642 "Motif" in this policy document.
8644 should be compiled against and tested with LessTif (a free
8645 re-implementation of Motif) instead. If the maintainer
8646 judges that the program or programs do not work
8647 sufficiently well with LessTif to be distributed and
8648 supported, but do so when compiled against Motif, then two
8649 versions of the package should be created; one linked
8650 statically against Motif and with <tt>-smotif</tt>
8651 appended to the package name, and one linked dynamically
8652 against Motif and with <tt>-dmotif</tt> appended to the
8657 Both Motif-linked versions are dependent
8658 upon non-DFSG-compliant software and thus cannot be
8659 uploaded to the <em>main</em> distribution; if the
8660 software is itself DFSG-compliant it may be uploaded to
8661 the <em>contrib</em> distribution. While known existing
8662 versions of Motif permit unlimited redistribution of
8663 binaries linked against the library (whether statically or
8664 dynamically), it is the package maintainer's
8665 responsibility to determine whether this is permitted by
8666 the license of the copy of Motif in their possession.
8672 <heading>Perl programs and modules</heading>
8675 Perl programs and modules should follow the current Perl policy.
8679 The Perl policy can be found in the <tt>perl-policy</tt>
8680 files in the <tt>debian-policy</tt> package.
8681 It is also available from the Debian web mirrors at
8682 <tt><url name="/doc/packaging-manuals/perl-policy/"
8683 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8688 <heading>Emacs lisp programs</heading>
8691 Please refer to the "Debian Emacs Policy" for details of how to
8692 package emacs lisp programs.
8696 The Emacs policy is available in
8697 <file>debian-emacs-policy.gz</file> of the
8698 <package>emacsen-common</package> package.
8699 It is also available from the Debian web mirrors at
8700 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8701 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8706 <heading>Games</heading>
8709 The permissions on <file>/var/games</file> are mode 755, owner
8710 <tt>root</tt> and group <tt>root</tt>.
8714 Each game decides on its own security policy.</p>
8717 Games which require protected, privileged access to
8718 high-score files, saved games, etc., may be made
8719 set-<em>group</em>-id (mode 2755) and owned by
8720 <tt>root:games</tt>, and use files and directories with
8721 appropriate permissions (770 <tt>root:games</tt>, for
8722 example). They must not be made
8723 set-<em>user</em>-id, as this causes security problems. (If
8724 an attacker can subvert any set-user-id game they can
8725 overwrite the executable of any other, causing other players
8726 of these games to run a Trojan horse program. With a
8727 set-group-id game the attacker only gets access to less
8728 important game data, and if they can get at the other
8729 players' accounts at all it will take considerably more
8733 Some packages, for example some fortune cookie programs, are
8734 configured by the upstream authors to install with their
8735 data files or other static information made unreadable so
8736 that they can only be accessed through set-id programs
8737 provided. You should not do this in a Debian package: anyone can
8738 download the <file>.deb</file> file and read the data from it,
8739 so there is no point making the files unreadable. Not
8740 making the files unreadable also means that you don't have
8741 to make so many programs set-id, which reduces the risk of a
8745 As described in the FHS, binaries of games should be
8746 installed in the directory <file>/usr/games</file>. This also
8747 applies to games that use the X Window System. Manual pages
8748 for games (X and non-X games) should be installed in
8749 <file>/usr/share/man/man6</file>.</p>
8755 <heading>Documentation</heading>
8758 <heading>Manual pages</heading>
8761 You should install manual pages in <prgn>nroff</prgn> source
8762 form, in appropriate places under <file>/usr/share/man</file>.
8763 You should only use sections 1 to 9 (see the FHS for more
8764 details). You must not install a pre-formatted "cat page".
8768 Each program, utility, and function should have an
8769 associated manual page included in the same package. It is
8770 suggested that all configuration files also have a manual
8771 page included as well. Manual pages for protocols and other
8772 auxiliary things are optional.
8776 If no manual page is available, this is considered as a bug
8777 and should be reported to the Debian Bug Tracking System (the
8778 maintainer of the package is allowed to write this bug report
8779 themselves, if they so desire). Do not close the bug report
8780 until a proper man page is available.<footnote>
8781 It is not very hard to write a man page. See the
8782 <url id="http://www.schweikhardt.net/man_page_howto.html"
8783 name="Man-Page-HOWTO">,
8784 <manref name="man" section="7">, the examples
8785 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8786 the helper programs <prgn>help2man</prgn>, or the
8787 directory <file>/usr/share/doc/man-db/examples</file>.
8792 You may forward a complaint about a missing man page to the
8793 upstream authors, and mark the bug as forwarded in the
8794 Debian bug tracking system. Even though the GNU Project do
8795 not in general consider the lack of a man page to be a bug,
8796 we do; if they tell you that they don't consider it a bug
8797 you should leave the bug in our bug tracking system open
8802 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8806 If one man page needs to be accessible via several names it
8807 is better to use a symbolic link than the <file>.so</file>
8808 feature, but there is no need to fiddle with the relevant
8809 parts of the upstream source to change from <file>.so</file> to
8810 symlinks: don't do it unless it's easy. You should not
8811 create hard links in the manual page directories, nor put
8812 absolute filenames in <file>.so</file> directives. The filename
8813 in a <file>.so</file> in a man page should be relative to the
8814 base of the man page tree (usually
8815 <file>/usr/share/man</file>). If you do not create any links
8816 (whether symlinks, hard links, or <tt>.so</tt> directives)
8817 in the file system to the alternate names of the man page,
8818 then you should not rely on <prgn>man</prgn> finding your
8819 man page under those names based solely on the information in
8820 the man page's header.<footnote>
8821 Supporting this in <prgn>man</prgn> often requires
8822 unreasonable processing time to find a manual page or to
8823 report that none exists, and moves knowledge into man's
8824 database that would be better left in the file system.
8825 This support is therefore deprecated and will cease to
8826 be present in the future.
8831 Manual pages in locale-specific subdirectories of
8832 <file>/usr/share/man</file> should use either UTF-8 or the usual
8833 legacy encoding for that language (normally the one corresponding
8834 to the shortest relevant locale name in
8835 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8836 <file>/usr/share/man/fr</file> should use either UTF-8 or
8837 ISO-8859-1.<footnote>
8838 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8839 use. In future, all manual pages will be required to use
8845 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8846 included in the subdirectory name unless it indicates a
8847 significant difference in the language, as this excludes
8848 speakers of the language in other countries.<footnote>
8849 At the time of writing, Chinese and Portuguese are the main
8850 languages with such differences, so <file>pt_BR</file>,
8851 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8856 If a localized version of a manual page is provided, it should
8857 either be up-to-date or it should be obvious to the reader that
8858 it is outdated and the original manual page should be used
8859 instead. This can be done either by a note at the beginning of
8860 the manual page or by showing the missing or changed portions in
8861 the original language instead of the target language.
8866 <heading>Info documents</heading>
8869 Info documents should be installed in <file>/usr/share/info</file>.
8870 They should be compressed with <tt>gzip -9</tt>.
8874 The <prgn>install-info</prgn> program maintains a directory of
8875 installed info documents in <file>/usr/share/info/dir</file> for
8876 the use of info readers.<footnote>
8877 It was previously necessary for packages installing info
8878 documents to run <prgn>install-info</prgn> from maintainer
8879 scripts. This is no longer necessary. The installation
8880 system now uses dpkg triggers.
8882 This file must not be included in packages. Packages containing
8883 info documents should depend on <tt>dpkg (>= 1.15.4) |
8884 install-info</tt> to ensure that the directory file is properly
8885 rebuilt during partial upgrades from Debian 5.0 (lenny) and
8890 Info documents should contain section and directory entry
8891 information in the document for the use
8892 of <prgn>install-info</prgn>. The section should be specified
8893 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8894 space and the section of this info page. The directory entry or
8895 entries should be included between
8896 a <tt>START-INFO-DIR-ENTRY</tt> line and
8897 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8899 INFO-DIR-SECTION Individual utilities
8900 START-INFO-DIR-ENTRY
8901 * example: (example). An example info directory entry.
8904 To determine which section to use, you should look
8905 at <file>/usr/share/info/dir</file> on your system and choose
8906 the most relevant (or create a new section if none of the
8907 current sections are relevant).<footnote>
8908 Normally, info documents are generated from Texinfo source.
8909 To include this information in the generated info document, if
8910 it is absent, add commands like:
8912 @dircategory Individual utilities
8914 * example: (example). An example info directory entry.
8917 to the Texinfo source of the document and ensure that the info
8918 documents are rebuilt from source during the package build.
8924 <heading>Additional documentation</heading>
8927 Any additional documentation that comes with the package may
8928 be installed at the discretion of the package maintainer.
8929 Plain text documentation should be installed in the directory
8930 <file>/usr/share/doc/<var>package</var></file>, where
8931 <var>package</var> is the name of the package, and
8932 compressed with <tt>gzip -9</tt> unless it is small.
8936 If a package comes with large amounts of documentation which
8937 many users of the package will not require you should create
8938 a separate binary package to contain it, so that it does not
8939 take up disk space on the machines of users who do not need
8940 or want it installed.</p>
8943 It is often a good idea to put text information files
8944 (<file>README</file>s, changelogs, and so forth) that come with
8945 the source package in <file>/usr/share/doc/<var>package</var></file>
8946 in the binary package. However, you don't need to install
8947 the instructions for building and installing the package, of
8951 Packages must not require the existence of any files in
8952 <file>/usr/share/doc/</file> in order to function
8954 The system administrator should be able to
8955 delete files in <file>/usr/share/doc/</file> without causing
8956 any programs to break.
8958 Any files that are referenced by programs but are also
8959 useful as stand alone documentation should be installed under
8960 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8961 <file>/usr/share/doc/<var>package</var></file>.
8965 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8966 link to another directory in <file>/usr/share/doc</file> only if
8967 the two packages both come from the same source and the
8968 first package Depends on the second.<footnote>
8970 Please note that this does not override the section on
8971 changelog files below, so the file
8972 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8973 must refer to the changelog for the current version of
8974 <var>package</var> in question. In practice, this means
8975 that the sources of the target and the destination of the
8976 symlink must be the same (same source package and
8983 Former Debian releases placed all additional documentation
8984 in <file>/usr/doc/<var>package</var></file>. This has been
8985 changed to <file>/usr/share/doc/<var>package</var></file>,
8986 and packages must not put documentation in the directory
8987 <file>/usr/doc/<var>package</var></file>. <footnote>
8988 At this phase of the transition, we no longer require a
8989 symbolic link in <file>/usr/doc/</file>. At a later point,
8990 policy shall change to make the symbolic links a bug.
8996 <heading>Preferred documentation formats</heading>
8999 The unification of Debian documentation is being carried out
9003 If your package comes with extensive documentation in a
9004 markup format that can be converted to various other formats
9005 you should if possible ship HTML versions in a binary
9006 package, in the directory
9007 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9008 its subdirectories.<footnote>
9009 The rationale: The important thing here is that HTML
9010 docs should be available in <em>some</em> package, not
9011 necessarily in the main binary package.
9016 Other formats such as PostScript may be provided at the
9017 package maintainer's discretion.
9021 <sect id="copyrightfile">
9022 <heading>Copyright information</heading>
9025 Every package must be accompanied by a verbatim copy of its
9026 copyright and distribution license in the file
9027 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9028 file must neither be compressed nor be a symbolic link.
9032 In addition, the copyright file must say where the upstream
9033 sources (if any) were obtained. It should name the original
9034 authors of the package and the Debian maintainer(s) who were
9035 involved with its creation.
9039 Packages in the <em>contrib</em> or <em>non-free</em> archive
9040 areas should state in the copyright file that the package is not
9041 part of the Debian GNU/Linux distribution and briefly explain
9046 A copy of the file which will be installed in
9047 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9048 be in <file>debian/copyright</file> in the source package.
9052 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9053 link to another directory in <file>/usr/share/doc</file> only if
9054 the two packages both come from the same source and the
9055 first package Depends on the second. These rules are
9056 important because copyrights must be extractable by
9061 Packages distributed under the UCB BSD license, the Apache
9062 license (version 2.0), the Artistic license, the GNU GPL
9063 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9064 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9065 files under <file>/usr/share/common-licenses</file>,<footnote>
9068 <file>/usr/share/common-licenses/BSD</file>,
9069 <file>/usr/share/common-licenses/Apache-2.0</file>,
9070 <file>/usr/share/common-licenses/Artistic</file>,
9071 <file>/usr/share/common-licenses/GPL-2</file>,
9072 <file>/usr/share/common-licenses/GPL-3</file>,
9073 <file>/usr/share/common-licenses/LGPL-2</file>,
9074 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9075 <file>/usr/share/common-licenses/LGPL-3</file>,
9076 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9077 <file>/usr/share/common-licenses/GFDL-1.3</file>
9080 </footnote> rather than quoting them in the copyright
9085 You should not use the copyright file as a general <file>README</file>
9086 file. If your package has such a file it should be
9087 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9088 <file>README.Debian</file> or some other appropriate place.</p>
9092 <heading>Examples</heading>
9095 Any examples (configurations, source files, whatever),
9096 should be installed in a directory
9097 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9098 files should not be referenced by any program: they're there
9099 for the benefit of the system administrator and users as
9100 documentation only. Architecture-specific example files
9101 should be installed in a directory
9102 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9104 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9105 latter directory itself may be a symbolic link to the
9110 If the purpose of a package is to provide examples, then the
9111 example files may be installed into
9112 <file>/usr/share/doc/<var>package</var></file>.
9116 <sect id="changelogs">
9117 <heading>Changelog files</heading>
9120 Packages that are not Debian-native must contain a
9121 compressed copy of the <file>debian/changelog</file> file from
9122 the Debian source tree in
9123 <file>/usr/share/doc/<var>package</var></file> with the name
9124 <file>changelog.Debian.gz</file>.
9128 If an upstream changelog is available, it should be accessible as
9129 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9130 plain text. If the upstream changelog is distributed in
9131 HTML, it should be made available in that form as
9132 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9133 and a plain text <file>changelog.gz</file> should be generated
9134 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9135 the upstream changelog files do not already conform to this
9136 naming convention, then this may be achieved either by
9137 renaming the files, or by adding a symbolic link, at the
9138 maintainer's discretion.<footnote>
9139 Rationale: People should not have to look in places for
9140 upstream changelogs merely because they are given
9141 different names or are distributed in HTML format.
9146 All of these files should be installed compressed using
9147 <tt>gzip -9</tt>, as they will become large with time even
9148 if they start out small.
9152 If the package has only one changelog which is used both as
9153 the Debian changelog and the upstream one because there is
9154 no separate upstream maintainer then that changelog should
9155 usually be installed as
9156 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9157 there is a separate upstream maintainer, but no upstream
9158 changelog, then the Debian changelog should still be called
9159 <file>changelog.Debian.gz</file>.
9163 For details about the format and contents of the Debian
9164 changelog file, please see <ref id="dpkgchangelog">.
9169 <appendix id="pkg-scope">
9170 <heading>Introduction and scope of these appendices</heading>
9173 These appendices are taken essentially verbatim from the
9174 now-deprecated Packaging Manual, version 3.2.1.0. They are
9175 the chapters which are likely to be of use to package
9176 maintainers and which have not already been included in the
9177 policy document itself. Most of these sections are very likely
9178 not relevant to policy; they should be treated as
9179 documentation for the packaging system. Please note that these
9180 appendices are included for convenience, and for historical
9181 reasons: they used to be part of policy package, and they have
9182 not yet been incorporated into dpkg documentation. However,
9183 they still have value, and hence they are presented here.
9187 They have not yet been checked to ensure that they are
9188 compatible with the contents of policy, and if there are any
9189 contradictions, the version in the main policy document takes
9190 precedence. The remaining chapters of the old Packaging
9191 Manual have also not been read in detail to ensure that there
9192 are not parts which have been left out. Both of these will be
9197 Certain parts of the Packaging manual were integrated into the
9198 Policy Manual proper, and removed from the appendices. Links
9199 have been placed from the old locations to the new ones.
9203 <prgn>dpkg</prgn> is a suite of programs for creating binary
9204 package files and installing and removing them on Unix
9206 <prgn>dpkg</prgn> is targeted primarily at Debian
9207 GNU/Linux, but may work on or be ported to other
9213 The binary packages are designed for the management of
9214 installed executable programs (usually compiled binaries) and
9215 their associated data, though source code examples and
9216 documentation are provided as part of some packages.</p>
9219 This manual describes the technical aspects of creating Debian
9220 binary packages (<file>.deb</file> files). It documents the
9221 behavior of the package management programs
9222 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9223 they interact with packages.</p>
9226 It also documents the interaction between
9227 <prgn>dselect</prgn>'s core and the access method scripts it
9228 uses to actually install the selected packages, and describes
9229 how to create a new access method.</p>
9232 This manual does not go into detail about the options and
9233 usage of the package building and installation tools. It
9234 should therefore be read in conjunction with those programs'
9239 The utility programs which are provided with <prgn>dpkg</prgn>
9240 for managing various system configuration and similar issues,
9241 such as <prgn>update-rc.d</prgn> and
9242 <prgn>install-info</prgn>, are not described in detail here -
9243 please see their man pages.
9247 It is assumed that the reader is reasonably familiar with the
9248 <prgn>dpkg</prgn> System Administrators' manual.
9249 Unfortunately this manual does not yet exist.
9253 The Debian version of the FSF's GNU hello program is provided
9254 as an example for people wishing to create Debian
9255 packages. The Debian <prgn>debmake</prgn> package is
9256 recommended as a very helpful tool in creating and maintaining
9257 Debian packages. However, while the tools and examples are
9258 helpful, they do not replace the need to read and follow the
9259 Policy and Programmer's Manual.</p>
9262 <appendix id="pkg-binarypkg">
9263 <heading>Binary packages (from old Packaging Manual)</heading>
9266 The binary package has two main sections. The first part
9267 consists of various control information files and scripts used
9268 by <prgn>dpkg</prgn> when installing and removing. See <ref
9269 id="pkg-controlarea">.
9273 The second part is an archive containing the files and
9274 directories to be installed.
9278 In the future binary packages may also contain other
9279 components, such as checksums and digital signatures. The
9280 format for the archive is described in full in the
9281 <file>deb(5)</file> man page.
9285 <sect id="pkg-bincreating"><heading>Creating package files -
9286 <prgn>dpkg-deb</prgn>
9290 All manipulation of binary package files is done by
9291 <prgn>dpkg-deb</prgn>; it's the only program that has
9292 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9293 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9294 will spot that the options requested are appropriate to
9295 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9300 In order to create a binary package you must make a
9301 directory tree which contains all the files and directories
9302 you want to have in the file system data part of the package.
9303 In Debian-format source packages this directory is usually
9304 <file>debian/tmp</file>, relative to the top of the package's
9309 They should have the locations (relative to the root of the
9310 directory tree you're constructing) ownerships and
9311 permissions which you want them to have on the system when
9316 With current versions of <prgn>dpkg</prgn> the uid/username
9317 and gid/groupname mappings for the users and groups being
9318 used should be the same on the system where the package is
9319 built and the one where it is installed.
9323 You need to add one special directory to the root of the
9324 miniature file system tree you're creating:
9325 <prgn>DEBIAN</prgn>. It should contain the control
9326 information files, notably the binary package control file
9327 (see <ref id="pkg-controlfile">).
9331 The <prgn>DEBIAN</prgn> directory will not appear in the
9332 file system archive of the package, and so won't be installed
9333 by <prgn>dpkg</prgn> when the package is unpacked.
9337 When you've prepared the package, you should invoke:
9339 dpkg --build <var>directory</var>
9344 This will build the package in
9345 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9346 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9347 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9352 See the man page <manref name="dpkg-deb" section="8"> for details of how
9353 to examine the contents of this newly-created file. You may find the
9354 output of following commands enlightening:
9356 dpkg-deb --info <var>filename</var>.deb
9357 dpkg-deb --contents <var>filename</var>.deb
9358 dpkg --contents <var>filename</var>.deb
9360 To view the copyright file for a package you could use this command:
9362 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9367 <sect id="pkg-controlarea">
9368 <heading>Package control information files</heading>
9371 The control information portion of a binary package is a
9372 collection of files with names known to <prgn>dpkg</prgn>.
9373 It will treat the contents of these files specially - some
9374 of them contain information used by <prgn>dpkg</prgn> when
9375 installing or removing the package; others are scripts which
9376 the package maintainer wants <prgn>dpkg</prgn> to run.
9380 It is possible to put other files in the package control
9381 area, but this is not generally a good idea (though they
9382 will largely be ignored).
9386 Here is a brief list of the control info files supported by
9387 <prgn>dpkg</prgn> and a summary of what they're used for.
9392 <tag><tt>control</tt>
9395 This is the key description file used by
9396 <prgn>dpkg</prgn>. It specifies the package's name
9397 and version, gives its description for the user,
9398 states its relationships with other packages, and so
9399 forth. See <ref id="sourcecontrolfiles"> and
9400 <ref id="binarycontrolfiles">.
9404 It is usually generated automatically from information
9405 in the source package by the
9406 <prgn>dpkg-gencontrol</prgn> program, and with
9407 assistance from <prgn>dpkg-shlibdeps</prgn>.
9408 See <ref id="pkg-sourcetools">.
9412 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9417 These are executable files (usually scripts) which
9418 <prgn>dpkg</prgn> runs during installation, upgrade
9419 and removal of packages. They allow the package to
9420 deal with matters which are particular to that package
9421 or require more complicated processing than that
9422 provided by <prgn>dpkg</prgn>. Details of when and
9423 how they are called are in <ref id="maintainerscripts">.
9427 It is very important to make these scripts idempotent.
9428 See <ref id="idempotency">.
9432 The maintainer scripts are guaranteed to run with a
9433 controlling terminal and can interact with the user.
9434 See <ref id="controllingterminal">.
9438 <tag><tt>conffiles</tt>
9441 This file contains a list of configuration files which
9442 are to be handled automatically by <prgn>dpkg</prgn>
9443 (see <ref id="pkg-conffiles">). Note that not necessarily
9444 every configuration file should be listed here.
9447 <tag><tt>shlibs</tt>
9450 This file contains a list of the shared libraries
9451 supplied by the package, with dependency details for
9452 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9453 when it determines what dependencies are required in a
9454 package control file. The <tt>shlibs</tt> file format
9455 is described on <ref id="shlibs">.
9460 <sect id="pkg-controlfile">
9461 <heading>The main control information file: <tt>control</tt></heading>
9464 The most important control information file used by
9465 <prgn>dpkg</prgn> when it installs a package is
9466 <tt>control</tt>. It contains all the package's "vital
9471 The binary package control files of packages built from
9472 Debian sources are made by a special tool,
9473 <prgn>dpkg-gencontrol</prgn>, which reads
9474 <file>debian/control</file> and <file>debian/changelog</file> to
9475 find the information it needs. See <ref id="pkg-sourcepkg"> for
9480 The fields in binary package control files are listed in
9481 <ref id="binarycontrolfiles">.
9485 A description of the syntax of control files and the purpose
9486 of the fields is available in <ref id="controlfields">.
9491 <heading>Time Stamps</heading>
9494 See <ref id="timestamps">.
9499 <appendix id="pkg-sourcepkg">
9500 <heading>Source packages (from old Packaging Manual) </heading>
9503 The Debian binary packages in the distribution are generated
9504 from Debian sources, which are in a special format to assist
9505 the easy and automatic building of binaries.
9508 <sect id="pkg-sourcetools">
9509 <heading>Tools for processing source packages</heading>
9512 Various tools are provided for manipulating source packages;
9513 they pack and unpack sources and help build of binary
9514 packages and help manage the distribution of new versions.
9518 They are introduced and typical uses described here; see
9519 <manref name="dpkg-source" section="1"> for full
9520 documentation about their arguments and operation.
9524 For examples of how to construct a Debian source package,
9525 and how to use those utilities that are used by Debian
9526 source packages, please see the <prgn>hello</prgn> example
9530 <sect1 id="pkg-dpkg-source">
9532 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9537 This program is frequently used by hand, and is also
9538 called from package-independent automated building scripts
9539 such as <prgn>dpkg-buildpackage</prgn>.
9543 To unpack a package it is typically invoked with
9545 dpkg-source -x <var>.../path/to/filename</var>.dsc
9550 with the <file><var>filename</var>.tar.gz</file> and
9551 <file><var>filename</var>.diff.gz</file> (if applicable) in
9552 the same directory. It unpacks into
9553 <file><var>package</var>-<var>version</var></file>, and if
9555 <file><var>package</var>-<var>version</var>.orig</file>, in
9556 the current directory.
9560 To create a packed source archive it is typically invoked:
9562 dpkg-source -b <var>package</var>-<var>version</var>
9567 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9568 <file>.diff.gz</file> (if appropriate) in the current
9569 directory. <prgn>dpkg-source</prgn> does not clean the
9570 source tree first - this must be done separately if it is
9575 See also <ref id="pkg-sourcearchives">.</p>
9579 <sect1 id="pkg-dpkg-buildpackage">
9581 <prgn>dpkg-buildpackage</prgn> - overall package-building
9586 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9587 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9588 targets <tt>clean</tt>, <tt>build</tt> and
9589 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9590 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9591 source and binary package upload.
9595 It is usually invoked by hand from the top level of the
9596 built or unbuilt source directory. It may be invoked with
9597 no arguments; useful arguments include:
9598 <taglist compact="compact">
9599 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9602 Do not sign the <tt>.changes</tt> file or the
9603 source package <tt>.dsc</tt> file, respectively.</p>
9605 <tag><tt>-p<var>sign-command</var></tt></tag>
9608 Invoke <var>sign-command</var> instead of finding
9609 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9610 <var>sign-command</var> must behave just like
9611 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9613 <tag><tt>-r<var>root-command</var></tt></tag>
9616 When root privilege is required, invoke the command
9617 <var>root-command</var>. <var>root-command</var>
9618 should invoke its first argument as a command, from
9619 the <prgn>PATH</prgn> if necessary, and pass its
9620 second and subsequent arguments to the command it
9621 calls. If no <var>root-command</var> is supplied
9622 then <var>dpkg-buildpackage</var> will take no
9623 special action to gain root privilege, so that for
9624 most packages it will have to be invoked as root to
9627 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9630 Two types of binary-only build and upload - see
9631 <manref name="dpkg-source" section="1">.
9638 <sect1 id="pkg-dpkg-gencontrol">
9640 <prgn>dpkg-gencontrol</prgn> - generates binary package
9645 This program is usually called from <file>debian/rules</file>
9646 (see <ref id="pkg-sourcetree">) in the top level of the source
9651 This is usually done just before the files and directories in the
9652 temporary directory tree where the package is being built have their
9653 permissions and ownerships set and the package is constructed using
9654 <prgn>dpkg-deb/</prgn>
9656 This is so that the control file which is produced has
9657 the right permissions
9662 <prgn>dpkg-gencontrol</prgn> must be called after all the
9663 files which are to go into the package have been placed in
9664 the temporary build directory, so that its calculation of
9665 the installed size of a package is correct.
9669 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9670 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9671 variable substitutions created by
9672 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9677 For a package which generates only one binary package, and
9678 which builds it in <file>debian/tmp</file> relative to the top
9679 of the source package, it is usually sufficient to call
9680 <prgn>dpkg-gencontrol</prgn>.
9684 Sources which build several binaries will typically need
9687 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9688 </example> The <tt>-P</tt> tells
9689 <prgn>dpkg-gencontrol</prgn> that the package is being
9690 built in a non-default directory, and the <tt>-p</tt>
9691 tells it which package's control file should be generated.
9695 <prgn>dpkg-gencontrol</prgn> also adds information to the
9696 list of files in <file>debian/files</file>, for the benefit of
9697 (for example) a future invocation of
9698 <prgn>dpkg-genchanges</prgn>.</p>
9701 <sect1 id="pkg-dpkg-shlibdeps">
9703 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9708 This program is usually called from <file>debian/rules</file>
9709 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9710 id="pkg-sourcetree">), in the top level of the source tree.
9714 Its arguments are executables and shared libraries
9717 They may be specified either in the locations in the
9718 source tree where they are created or in the locations
9719 in the temporary build tree where they are installed
9720 prior to binary package creation.
9722 </footnote> for which shared library dependencies should
9723 be included in the binary package's control file.
9727 If some of the found shared libraries should only
9728 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9729 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9730 by using the <tt>-d<var>dependency-field</var></tt> option
9731 before those executable(s). (Each <tt>-d</tt> option
9732 takes effect until the next <tt>-d</tt>.)
9736 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9737 output control file to be modified. Instead by default it
9738 adds to the <file>debian/substvars</file> file variable
9739 settings like <tt>shlibs:Depends</tt>. These variable
9740 settings must be referenced in dependency fields in the
9741 appropriate per-binary-package sections of the source
9746 For example, a package that generates an essential part
9747 which requires dependencies, and optional parts that
9748 which only require a recommendation, would separate those
9749 two sets of dependencies into two different fields.<footnote>
9750 At the time of writing, an example for this was the
9751 <package/xmms/ package, with Depends used for the xmms
9752 executable, Recommends for the plug-ins and Suggests for
9753 even more optional features provided by unzip.
9755 It can say in its <file>debian/rules</file>:
9757 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9758 -dRecommends <var>optionalpart anotheroptionalpart</var>
9760 and then in its main control file <file>debian/control</file>:
9763 Depends: ${shlibs:Depends}
9764 Recommends: ${shlibs:Recommends}
9770 Sources which produce several binary packages with
9771 different shared library dependency requirements can use
9772 the <tt>-p<var>varnameprefix</var></tt> option to override
9773 the default <tt>shlibs:</tt> prefix (one invocation of
9774 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9775 They can thus produce several sets of dependency
9776 variables, each of the form
9777 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9778 which can be referred to in the appropriate parts of the
9779 binary package control files.
9784 <sect1 id="pkg-dpkg-distaddfile">
9786 <prgn>dpkg-distaddfile</prgn> - adds a file to
9787 <file>debian/files</file>
9791 Some packages' uploads need to include files other than
9792 the source and binary package files.
9796 <prgn>dpkg-distaddfile</prgn> adds a file to the
9797 <file>debian/files</file> file so that it will be included in
9798 the <file>.changes</file> file when
9799 <prgn>dpkg-genchanges</prgn> is run.
9803 It is usually invoked from the <tt>binary</tt> target of
9804 <file>debian/rules</file>:
9806 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9808 The <var>filename</var> is relative to the directory where
9809 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9810 is usually the directory above the top level of the source
9811 tree. The <file>debian/rules</file> target should put the
9812 file there just before or just after calling
9813 <prgn>dpkg-distaddfile</prgn>.
9817 The <var>section</var> and <var>priority</var> are passed
9818 unchanged into the resulting <file>.changes</file> file.
9823 <sect1 id="pkg-dpkg-genchanges">
9825 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9830 This program is usually called by package-independent
9831 automatic building scripts such as
9832 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9837 It is usually called in the top level of a built source
9838 tree, and when invoked with no arguments will print out a
9839 straightforward <file>.changes</file> file based on the
9840 information in the source package's changelog and control
9841 file and the binary and source packages which should have
9847 <sect1 id="pkg-dpkg-parsechangelog">
9849 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9850 representation of a changelog
9854 This program is used internally by
9855 <prgn>dpkg-source</prgn> et al. It may also occasionally
9856 be useful in <file>debian/rules</file> and elsewhere. It
9857 parses a changelog, <file>debian/changelog</file> by default,
9858 and prints a control-file format representation of the
9859 information in it to standard output.
9863 <sect1 id="pkg-dpkg-architecture">
9865 <prgn>dpkg-architecture</prgn> - information about the build and
9870 This program can be used manually, but is also invoked by
9871 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9872 environment or make variables which specify the build and host
9873 architecture for the package building process.
9878 <sect id="pkg-sourcetree">
9879 <heading>The Debianised source tree</heading>
9882 The source archive scheme described later is intended to
9883 allow a Debianised source tree with some associated control
9884 information to be reproduced and transported easily. The
9885 Debianised source tree is a version of the original program
9886 with certain files added for the benefit of the
9887 Debianisation process, and with any other changes required
9888 made to the rest of the source code and installation
9893 The extra files created for Debian are in the subdirectory
9894 <file>debian</file> of the top level of the Debianised source
9895 tree. They are described below.
9898 <sect1 id="pkg-debianrules">
9899 <heading><file>debian/rules</file> - the main building script</heading>
9902 See <ref id="debianrules">.
9907 <sect1 id="pkg-dpkgchangelog">
9908 <heading><file>debian/changelog</file></heading>
9911 See <ref id="dpkgchangelog">.
9914 <sect2><heading>Defining alternative changelog formats
9918 It is possible to use a different format to the standard
9919 one, by providing a parser for the format you wish to
9924 In order to have <tt>dpkg-parsechangelog</tt> run your
9925 parser, you must include a line within the last 40 lines
9926 of your file matching the Perl regular expression:
9927 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9928 parentheses should be the name of the format. For
9929 example, you might say:
9931 @@@ changelog-format: joebloggs @@@
9933 Changelog format names are non-empty strings of alphanumerics.
9937 If such a line exists then <tt>dpkg-parsechangelog</tt>
9938 will look for the parser as
9939 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9941 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9942 it is an error for it not to find it, or for it not to
9943 be an executable program. The default changelog format
9944 is <tt>dpkg</tt>, and a parser for it is provided with
9945 the <tt>dpkg</tt> package.
9949 The parser will be invoked with the changelog open on
9950 standard input at the start of the file. It should read
9951 the file (it may seek if it wishes) to determine the
9952 information required and return the parsed information
9953 to standard output in the form of a series of control
9954 fields in the standard format. By default it should
9955 return information about only the most recent version in
9956 the changelog; it should accept a
9957 <tt>-v<var>version</var></tt> option to return changes
9958 information from all versions present <em>strictly
9959 after</em> <var>version</var>, and it should then be an
9960 error for <var>version</var> not to be present in the
9966 <list compact="compact">
9967 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9968 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9969 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9970 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9971 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9972 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9973 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9978 If several versions are being returned (due to the use
9979 of <tt>-v</tt>), the urgency value should be of the
9980 highest urgency code listed at the start of any of the
9981 versions requested followed by the concatenated
9982 (space-separated) comments from all the versions
9983 requested; the maintainer, version, distribution and
9984 date should always be from the most recent version.
9988 For the format of the <tt>Changes</tt> field see
9989 <ref id="f-Changes">.
9993 If the changelog format which is being parsed always or
9994 almost always leaves a blank line between individual
9995 change notes these blank lines should be stripped out,
9996 so as to make the resulting output compact.
10000 If the changelog format does not contain date or package
10001 name information this information should be omitted from
10002 the output. The parser should not attempt to synthesize
10003 it or find it from other sources.
10007 If the changelog does not have the expected format the
10008 parser should exit with a nonzero exit status, rather
10009 than trying to muddle through and possibly generating
10014 A changelog parser may not interact with the user at
10020 <sect1 id="pkg-srcsubstvars">
10021 <heading><file>debian/substvars</file> and variable substitutions</heading>
10024 See <ref id="substvars">.
10030 <heading><file>debian/files</file></heading>
10033 See <ref id="debianfiles">.
10037 <sect1><heading><file>debian/tmp</file>
10041 This is the canonical temporary location for the
10042 construction of binary packages by the <tt>binary</tt>
10043 target. The directory <file>tmp</file> serves as the root of
10044 the file system tree as it is being constructed (for
10045 example, by using the package's upstream makefiles install
10046 targets and redirecting the output there), and it also
10047 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10048 id="pkg-bincreating">.
10052 If several binary packages are generated from the same
10053 source tree it is usual to use several
10054 <file>debian/tmp<var>something</var></file> directories, for
10055 example <file>tmp-a</file> or <file>tmp-doc</file>.
10059 Whatever <file>tmp</file> directories are created and used by
10060 <tt>binary</tt> must of course be removed by the
10061 <tt>clean</tt> target.</p></sect1>
10065 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10069 As it exists on the FTP site, a Debian source package
10070 consists of three related files. You must have the right
10071 versions of all three to be able to use them.
10076 <tag>Debian source control file - <tt>.dsc</tt></tag>
10078 This file is a control file used by <prgn>dpkg-source</prgn>
10079 to extract a source package.
10080 See <ref id="debiansourcecontrolfiles">.
10084 Original source archive -
10086 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10092 This is a compressed (with <tt>gzip -9</tt>)
10093 <prgn>tar</prgn> file containing the source code from
10094 the upstream authors of the program.
10099 Debianisation diff -
10101 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10107 This is a unified context diff (<tt>diff -u</tt>)
10108 giving the changes which are required to turn the
10109 original source into the Debian source. These changes
10110 may only include editing and creating plain files.
10111 The permissions of files, the targets of symbolic
10112 links and the characteristics of special files or
10113 pipes may not be changed and no files may be removed
10118 All the directories in the diff must exist, except the
10119 <file>debian</file> subdirectory of the top of the source
10120 tree, which will be created by
10121 <prgn>dpkg-source</prgn> if necessary when unpacking.
10125 The <prgn>dpkg-source</prgn> program will
10126 automatically make the <file>debian/rules</file> file
10127 executable (see below).</p></item>
10132 If there is no original source code - for example, if the
10133 package is specially prepared for Debian or the Debian
10134 maintainer is the same as the upstream maintainer - the
10135 format is slightly different: then there is no diff, and the
10137 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10138 and preferably contains a directory named
10139 <file><var>package</var>-<var>version</var></file>.
10144 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10147 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10148 Debian source package. However, if it is not available it
10149 is possible to unpack a Debian source archive as follows:
10150 <enumlist compact="compact">
10153 Untar the tarfile, which will create a <file>.orig</file>
10157 <p>Rename the <file>.orig</file> directory to
10158 <file><var>package</var>-<var>version</var></file>.</p>
10162 Create the subdirectory <file>debian</file> at the top of
10163 the source tree.</p>
10165 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10167 <item><p>Untar the tarfile again if you want a copy of the original
10168 source code alongside the Debianised version.</p>
10173 It is not possible to generate a valid Debian source archive
10174 without using <prgn>dpkg-source</prgn>. In particular,
10175 attempting to use <prgn>diff</prgn> directly to generate the
10176 <file>.diff.gz</file> file will not work.
10180 <heading>Restrictions on objects in source packages</heading>
10183 The source package may not contain any hard links
10185 This is not currently detected when building source
10186 packages, but only when extracting
10190 Hard links may be permitted at some point in the
10191 future, but would require a fair amount of
10193 </footnote>, device special files, sockets or setuid or
10196 Setgid directories are allowed.
10201 The source packaging tools manage the changes between the
10202 original and Debianised source using <prgn>diff</prgn> and
10203 <prgn>patch</prgn>. Turning the original source tree as
10204 included in the <file>.orig.tar.gz</file> into the debianised
10205 source must not involve any changes which cannot be
10206 handled by these tools. Problematic changes which cause
10207 <prgn>dpkg-source</prgn> to halt with an error when
10208 building the source package are:
10209 <list compact="compact">
10210 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10212 <item><p>Changing the targets of symbolic links.</p>
10214 <item><p>Creating directories, other than <file>debian</file>.</p>
10216 <item><p>Changes to the contents of binary files.</p></item>
10217 </list> Changes which cause <prgn>dpkg-source</prgn> to
10218 print a warning but continue anyway are:
10219 <list compact="compact">
10222 Removing files, directories or symlinks.
10224 Renaming a file is not treated specially - it is
10225 seen as the removal of the old file (which
10226 generates a warning, but is otherwise ignored),
10227 and the creation of the new one.
10233 Changed text files which are missing the usual final
10234 newline (either in the original or the modified
10239 Changes which are not represented, but which are not detected by
10240 <prgn>dpkg-source</prgn>, are:
10241 <list compact="compact">
10242 <item><p>Changing the permissions of files (other than
10243 <file>debian/rules</file>) and directories.</p></item>
10248 The <file>debian</file> directory and <file>debian/rules</file>
10249 are handled specially by <prgn>dpkg-source</prgn> - before
10250 applying the changes it will create the <file>debian</file>
10251 directory, and afterwards it will make
10252 <file>debian/rules</file> world-executable.
10258 <appendix id="pkg-controlfields">
10259 <heading>Control files and their fields (from old Packaging Manual)</heading>
10262 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10263 data in a common format, known as control files. Binary and
10264 source packages have control data as do the <file>.changes</file>
10265 files which control the installation of uploaded files, and
10266 <prgn>dpkg</prgn>'s internal databases are in a similar
10271 <heading>Syntax of control files</heading>
10274 See <ref id="controlsyntax">.
10278 It is important to note that there are several fields which
10279 are optional as far as <prgn>dpkg</prgn> and the related
10280 tools are concerned, but which must appear in every Debian
10281 package, or whose omission may cause problems.
10286 <heading>List of fields</heading>
10289 See <ref id="controlfieldslist">.
10293 This section now contains only the fields that didn't belong
10294 to the Policy manual.
10297 <sect1 id="pkg-f-Filename">
10298 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10301 These fields in <tt>Packages</tt> files give the
10302 filename(s) of (the parts of) a package in the
10303 distribution directories, relative to the root of the
10304 Debian hierarchy. If the package has been split into
10305 several parts the parts are all listed in order, separated
10310 <sect1 id="pkg-f-Size">
10311 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10314 These fields in <file>Packages</file> files give the size (in
10315 bytes, expressed in decimal) and MD5 checksum of the
10316 file(s) which make(s) up a binary package in the
10317 distribution. If the package is split into several parts
10318 the values for the parts are listed in order, separated by
10323 <sect1 id="pkg-f-Status">
10324 <heading><tt>Status</tt></heading>
10327 This field in <prgn>dpkg</prgn>'s status file records
10328 whether the user wants a package installed, removed or
10329 left alone, whether it is broken (requiring
10330 re-installation) or not and what its current state on the
10331 system is. Each of these pieces of information is a
10336 <sect1 id="pkg-f-Config-Version">
10337 <heading><tt>Config-Version</tt></heading>
10340 If a package is not installed or not configured, this
10341 field in <prgn>dpkg</prgn>'s status file records the last
10342 version of the package which was successfully
10347 <sect1 id="pkg-f-Conffiles">
10348 <heading><tt>Conffiles</tt></heading>
10351 This field in <prgn>dpkg</prgn>'s status file contains
10352 information about the automatically-managed configuration
10353 files held by a package. This field should <em>not</em>
10354 appear anywhere in a package!
10359 <heading>Obsolete fields</heading>
10362 These are still recognized by <prgn>dpkg</prgn> but should
10363 not appear anywhere any more.
10365 <taglist compact="compact">
10367 <tag><tt>Revision</tt></tag>
10368 <tag><tt>Package-Revision</tt></tag>
10369 <tag><tt>Package_Revision</tt></tag>
10371 The Debian revision part of the package version was
10372 at one point in a separate control file field. This
10373 field went through several names.
10376 <tag><tt>Recommended</tt></tag>
10377 <item>Old name for <tt>Recommends</tt>.</item>
10379 <tag><tt>Optional</tt></tag>
10380 <item>Old name for <tt>Suggests</tt>.</item>
10382 <tag><tt>Class</tt></tag>
10383 <item>Old name for <tt>Priority</tt>.</item>
10392 <appendix id="pkg-conffiles">
10393 <heading>Configuration file handling (from old Packaging Manual)</heading>
10396 <prgn>dpkg</prgn> can do a certain amount of automatic
10397 handling of package configuration files.
10401 Whether this mechanism is appropriate depends on a number of
10402 factors, but basically there are two approaches to any
10403 particular configuration file.
10407 The easy method is to ship a best-effort configuration in the
10408 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10409 handle updates. If the user is unlikely to want to edit the
10410 file, but you need them to be able to without losing their
10411 changes, and a new package with a changed version of the file
10412 is only released infrequently, this is a good approach.
10416 The hard method is to build the configuration file from
10417 scratch in the <prgn>postinst</prgn> script, and to take the
10418 responsibility for fixing any mistakes made in earlier
10419 versions of the package automatically. This will be
10420 appropriate if the file is likely to need to be different on
10424 <sect><heading>Automatic handling of configuration files by
10429 A package may contain a control area file called
10430 <tt>conffiles</tt>. This file should be a list of filenames
10431 of configuration files needing automatic handling, separated
10432 by newlines. The filenames should be absolute pathnames,
10433 and the files referred to should actually exist in the
10438 When a package is upgraded <prgn>dpkg</prgn> will process
10439 the configuration files during the configuration stage,
10440 shortly before it runs the package's <prgn>postinst</prgn>
10445 For each file it checks to see whether the version of the
10446 file included in the package is the same as the one that was
10447 included in the last version of the package (the one that is
10448 being upgraded from); it also compares the version currently
10449 installed on the system with the one shipped with the last
10454 If neither the user nor the package maintainer has changed
10455 the file, it is left alone. If one or the other has changed
10456 their version, then the changed version is preferred - i.e.,
10457 if the user edits their file, but the package maintainer
10458 doesn't ship a different version, the user's changes will
10459 stay, silently, but if the maintainer ships a new version
10460 and the user hasn't edited it the new version will be
10461 installed (with an informative message). If both have
10462 changed their version the user is prompted about the problem
10463 and must resolve the differences themselves.
10467 The comparisons are done by calculating the MD5 message
10468 digests of the files, and storing the MD5 of the file as it
10469 was included in the most recent version of the package.
10473 When a package is installed for the first time
10474 <prgn>dpkg</prgn> will install the file that comes with it,
10475 unless that would mean overwriting a file already on the
10480 However, note that <prgn>dpkg</prgn> will <em>not</em>
10481 replace a conffile that was removed by the user (or by a
10482 script). This is necessary because with some programs a
10483 missing file produces an effect hard or impossible to
10484 achieve in another way, so that a missing file needs to be
10485 kept that way if the user did it.
10489 Note that a package should <em>not</em> modify a
10490 <prgn>dpkg</prgn>-handled conffile in its maintainer
10491 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10492 the user confusing and possibly dangerous options for
10493 conffile update when the package is upgraded.</p>
10496 <sect><heading>Fully-featured maintainer script configuration
10501 For files which contain site-specific information such as
10502 the hostname and networking details and so forth, it is
10503 better to create the file in the package's
10504 <prgn>postinst</prgn> script.
10508 This will typically involve examining the state of the rest
10509 of the system to determine values and other information, and
10510 may involve prompting the user for some information which
10511 can't be obtained some other way.
10515 When using this method there are a couple of important
10516 issues which should be considered:
10520 If you discover a bug in the program which generates the
10521 configuration file, or if the format of the file changes
10522 from one version to the next, you will have to arrange for
10523 the postinst script to do something sensible - usually this
10524 will mean editing the installed configuration file to remove
10525 the problem or change the syntax. You will have to do this
10526 very carefully, since the user may have changed the file,
10527 perhaps to fix the very problem that your script is trying
10528 to deal with - you will have to detect these situations and
10529 deal with them correctly.
10533 If you do go down this route it's probably a good idea to
10534 make the program that generates the configuration file(s) a
10535 separate program in <file>/usr/sbin</file>, by convention called
10536 <file><var>package</var>config</file> and then run that if
10537 appropriate from the post-installation script. The
10538 <tt><var>package</var>config</tt> program should not
10539 unquestioningly overwrite an existing configuration - if its
10540 mode of operation is geared towards setting up a package for
10541 the first time (rather than any arbitrary reconfiguration
10542 later) you should have it check whether the configuration
10543 already exists, and require a <tt>--force</tt> flag to
10544 overwrite it.</p></sect>
10547 <appendix id="pkg-alternatives"><heading>Alternative versions of
10548 an interface - <prgn>update-alternatives</prgn> (from old
10553 When several packages all provide different versions of the
10554 same program or file it is useful to have the system select a
10555 default, but to allow the system administrator to change it
10556 and have their decisions respected.
10560 For example, there are several versions of the <prgn>vi</prgn>
10561 editor, and there is no reason to prevent all of them from
10562 being installed at once, each under their own name
10563 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10564 Nevertheless it is desirable to have the name <tt>vi</tt>
10565 refer to something, at least by default.
10569 If all the packages involved cooperate, this can be done with
10570 <prgn>update-alternatives</prgn>.
10574 Each package provides its own version under its own name, and
10575 calls <prgn>update-alternatives</prgn> in its postinst to
10576 register its version (and again in its prerm to deregister
10581 See the man page <manref name="update-alternatives"
10582 section="8"> for details.
10586 If <prgn>update-alternatives</prgn> does not seem appropriate
10587 you may wish to consider using diversions instead.</p>
10590 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10591 package's version of a file (from old Packaging Manual)
10595 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10596 when it reinstalls the package it belongs to, and to have it
10597 put the file from the package somewhere else instead.
10601 This can be used locally to override a package's version of a
10602 file, or by one package to override another's version (or
10603 provide a wrapper for it).
10607 Before deciding to use a diversion, read <ref
10608 id="pkg-alternatives"> to see if you really want a diversion
10609 rather than several alternative versions of a program.
10613 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10614 and updated by a special program <prgn>dpkg-divert</prgn>.
10615 Please see <manref name="dpkg-divert" section="8"> for full
10616 details of its operation.
10620 When a package wishes to divert a file from another, it should
10621 call <prgn>dpkg-divert</prgn> in its preinst to add the
10622 diversion and rename the existing file. For example,
10623 supposing that a <prgn>smailwrapper</prgn> package wishes to
10624 install a wrapper around <file>/usr/sbin/smail</file>:
10626 dpkg-divert --package smailwrapper --add --rename \
10627 --divert /usr/sbin/smail.real /usr/sbin/smail
10628 </example> The <tt>--package smailwrapper</tt> ensures that
10629 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10630 can bypass the diversion and get installed as the true version.
10631 It's safe to add the diversion unconditionally on upgrades since
10632 it will be left unchanged if it already exists, but
10633 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10634 message, make the command conditional on the version from which
10635 the package is being upgraded:
10637 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10638 dpkg-divert --package smailwrapper --add --rename \
10639 --divert /usr/sbin/smail.real /usr/sbin/smail
10641 </example> where <tt>1.0-2</tt> is the version at which the
10642 diversion was first added to the package. Running the command
10643 during abort-upgrade is pointless but harmless.
10647 The postrm has to do the reverse:
10649 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10650 dpkg-divert --package smailwrapper --remove --rename \
10651 --divert /usr/sbin/smail.real /usr/sbin/smail
10653 </example> If the diversion was added at a particular version, the
10654 postrm should also handle the failure case of upgrading from an
10655 older version (unless the older version is so old that direct
10656 upgrades are no longer supported):
10658 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10659 dpkg-divert --package smailwrapper --remove --rename \
10660 --divert /usr/sbin/smail.real /usr/sbin/smail
10662 </example> where <tt>1.02-2</tt> is the version at which the
10663 diversion was first added to the package. The postrm should not
10664 remove the diversion on upgrades both because there's no reason to
10665 remove the diversion only to immediately re-add it and since the
10666 postrm of the old package is run after unpacking so the removal of
10667 the diversion will fail.
10671 Do not attempt to divert a file which is vitally important for
10672 the system's operation - when using <prgn>dpkg-divert</prgn>
10673 there is a time, after it has been diverted but before
10674 <prgn>dpkg</prgn> has installed the new version, when the file
10675 does not exist.</p>
10680 <!-- Local variables: -->
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