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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interfaces not changing, and the package
94 management software authors need to ensure
95 compatibility with these interface
96 definitions. (Control file and changelog file
97 formats are examples.)
99 <tag>Chosen Convention</tag>
101 If there are a number of technically viable choices
102 that can be made, but one needs to select one of
103 these options for inter-operability. The version
104 number format is one example.
107 Please note that these are not mutually exclusive;
108 selected conventions often become parts of standard
114 The footnotes present in this manual are
115 merely informative, and are not part of Debian policy itself.
119 The appendices to this manual are not necessarily normative,
120 either. Please see <ref id="pkg-scope"> for more information.
124 In the normative part of this manual,
125 the words <em>must</em>, <em>should</em> and
126 <em>may</em>, and the adjectives <em>required</em>,
127 <em>recommended</em> and <em>optional</em>, are used to
128 distinguish the significance of the various guidelines in
129 this policy document. Packages that do not conform to the
130 guidelines denoted by <em>must</em> (or <em>required</em>)
131 will generally not be considered acceptable for the Debian
132 distribution. Non-conformance with guidelines denoted by
133 <em>should</em> (or <em>recommended</em>) will generally be
134 considered a bug, but will not necessarily render a package
135 unsuitable for distribution. Guidelines denoted by
136 <em>may</em> (or <em>optional</em>) are truly optional and
137 adherence is left to the maintainer's discretion.
141 These classifications are roughly equivalent to the bug
142 severities <em>serious</em> (for <em>must</em> or
143 <em>required</em> directive violations), <em>minor</em>,
144 <em>normal</em> or <em>important</em>
145 (for <em>should</em> or <em>recommended</em> directive
146 violations) and <em>wishlist</em> (for <em>optional</em>
149 Compare RFC 2119. Note, however, that these words are
150 used in a different way in this document.
155 Much of the information presented in this manual will be
156 useful even when building a package which is to be
157 distributed in some other way or is intended for local use
163 <heading>New versions of this document</heading>
166 This manual is distributed via the Debian package
167 <package><url name="debian-policy"
168 id="http://packages.debian.org/debian-policy"></package>
169 (<httpsite>packages.debian.org</httpsite>
170 <httppath>/debian-policy</httppath>).
174 The current version of this document is also available from
175 the Debian web mirrors at
176 <tt><url name="/doc/debian-policy/"
177 id="http://www.debian.org/doc/debian-policy/"></tt>.
179 <httpsite>www.debian.org</httpsite>
180 <httppath>/doc/debian-policy/</httppath>)
181 Also available from the same directory are several other
182 formats: <file>policy.html.tar.gz</file>
183 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
184 <file>policy.pdf.gz</file>
185 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
186 and <file>policy.ps.gz</file>
187 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
191 The <package>debian-policy</package> package also includes the file
192 <file>upgrading-checklist.txt.gz</file> which indicates policy
193 changes between versions of this document.
198 <heading>Authors and Maintainers</heading>
201 Originally called "Debian GNU/Linux Policy Manual", this
202 manual was initially written in 1996 by Ian Jackson.
203 It was revised on November 27th, 1996 by David A. Morris.
204 Christian Schwarz added new sections on March 15th, 1997,
205 and reworked/restructured it in April-July 1997.
206 Christoph Lameter contributed the "Web Standard".
207 Julian Gilbey largely restructured it in 2001.
211 Since September 1998, the responsibility for the contents of
212 this document lies on the <url name="debian-policy mailing list"
213 id="mailto:debian-policy@lists.debian.org">. Proposals
214 are discussed there and inserted into policy after a certain
215 consensus is established.
216 <!-- insert shameless policy-process plug here eventually -->
217 The actual editing is done by a group of maintainers that have
218 no editorial powers. These are the current maintainers:
221 <item>Julian Gilbey</item>
222 <item>Branden Robinson</item>
223 <item>Josip Rodin</item>
224 <item>Manoj Srivastava</item>
229 While the authors of this document have tried hard to avoid
230 typos and other errors, these do still occur. If you discover
231 an error in this manual or if you want to give any
232 comments, suggestions, or criticisms please send an email to
233 the Debian Policy List,
234 <email>debian-policy@lists.debian.org</email>, or submit a
235 bug report against the <tt>debian-policy</tt> package.
239 Please do not try to reach the individual authors or maintainers
240 of the Policy Manual regarding changes to the Policy.
245 <heading>Related documents</heading>
248 There are several other documents other than this Policy Manual
249 that are necessary to fully understand some Debian policies and
254 The external "sub-policy" documents are referred to in:
255 <list compact="compact">
256 <item><ref id="fhs"></item>
257 <item><ref id="virtual_pkg"></item>
258 <item><ref id="menus"></item>
259 <item><ref id="mime"></item>
260 <item><ref id="perl"></item>
261 <item><ref id="maintscriptprompt"></item>
262 <item><ref id="emacs"></item>
267 In addition to those, which carry the weight of policy, there
268 is the Debian Developer's Reference. This document describes
269 procedures and resources for Debian developers, but it is
270 <em>not</em> normative; rather, it includes things that don't
271 belong in the Policy, such as best practices for developers.
275 The Developer's Reference is available in the
276 <package>developers-reference</package> package.
277 It's also available from the Debian web mirrors at
278 <tt><url name="/doc/developers-reference/"
279 id="http://www.debian.org/doc/developers-reference/"></tt>.
283 <sect id="definitions">
284 <heading>Definitions</heading>
287 The following terms are used in this Policy Manual:
291 The character encoding specified by ANSI X3.4-1986 and its
292 predecessor standards, referred to in MIME as US-ASCII, and
293 corresponding to an encoding in eight bits per character of
294 the first 128 <url id="http://www.unicode.org/"
295 name="Unicode"> characters, with the eighth bit always zero.
299 The transformation format (sometimes called encoding) of
300 <url id="http://www.unicode.org/" name="Unicode"> defined by
301 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
302 name="RFC 3629">. UTF-8 has the useful property of having
303 ASCII as a subset, so any text encoded in ASCII is trivially
313 <heading>The Debian Archive</heading>
316 The Debian GNU/Linux system is maintained and distributed as a
317 collection of <em>packages</em>. Since there are so many of
318 them (currently well over 15000), they are split into
319 <em>sections</em> and given <em>priorities</em> to simplify
320 the handling of them.
324 The effort of the Debian project is to build a free operating
325 system, but not every package we want to make accessible is
326 <em>free</em> in our sense (see the Debian Free Software
327 Guidelines, below), or may be imported/exported without
328 restrictions. Thus, the archive is split into areas<footnote>
329 The Debian archive software uses the term "component" internally
330 and in the Release file format to refer to the division of an
331 archive. The Debian Social Contract simply refers to "areas."
332 This document uses terminology similar to the Social Contract.
333 </footnote> based on their licenses and other restrictions.
337 The aims of this are:
339 <list compact="compact">
340 <item>to allow us to make as much software available as we can</item>
341 <item>to allow us to encourage everyone to write free software,
343 <item>to allow us to make it easy for people to produce
344 CD-ROMs of our system without violating any licenses,
345 import/export restrictions, or any other laws.</item>
350 The <em>main</em> archive area forms the <em>Debian GNU/Linux
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 Every package in <em>main</em> must comply with the DFSG
469 (Debian Free Software Guidelines).
473 In addition, the packages in <em>main</em>
474 <list compact="compact">
476 must not require a package outside of <em>main</em>
477 for compilation or execution (thus, the package must
478 not declare a "Depends", "Recommends", or
479 "Build-Depends" relationship on a non-<em>main</em>
483 must not be so buggy that we refuse to support them,
487 must meet all policy requirements presented in this
496 <heading>The contrib archive area</heading>
499 Every package in <em>contrib</em> must comply with the DFSG.
503 In addition, the packages in <em>contrib</em>
504 <list compact="compact">
506 must not be so buggy that we refuse to support them,
510 must meet all policy requirements presented in this
518 Examples of packages which would be included in
519 <em>contrib</em> are:
520 <list compact="compact">
522 free packages which require <em>contrib</em>,
523 <em>non-free</em> packages or packages which are not
524 in our archive at all for compilation or execution,
528 wrapper packages or other sorts of free accessories for
535 <sect1 id="non-free">
536 <heading>The non-free archive area</heading>
539 Packages must be placed in <em>non-free</em> if they are
540 not compliant with the DFSG or are encumbered by patents
541 or other legal issues that make their distribution
546 In addition, the packages in <em>non-free</em>
547 <list compact="compact">
549 must not be so buggy that we refuse to support them,
553 must meet all policy requirements presented in this
554 manual that it is possible for them to meet.
556 It is possible that there are policy
557 requirements which the package is unable to
558 meet, for example, if the source is
559 unavailable. These situations will need to be
560 handled on a case-by-case basis.
569 <sect id="pkgcopyright">
570 <heading>Copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of
574 its copyright and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
580 We reserve the right to restrict files from being included
581 anywhere in our archives if
582 <list compact="compact">
584 their use or distribution would break a law,
587 there is an ethical conflict in their distribution or
591 we would have to sign a license for them, or
594 their distribution would conflict with other project
601 Programs whose authors encourage the user to make
602 donations are fine for the main distribution, provided
603 that the authors do not claim that not donating is
604 immoral, unethical, illegal or something similar; in such
605 a case they must go in <em>non-free</em>.
609 Packages whose copyright permission notices (or patent
610 problems) do not even allow redistribution of binaries
611 only, and where no special permission has been obtained,
612 must not be placed on the Debian FTP site and its mirrors
617 Note that under international copyright law (this applies
618 in the United States, too), <em>no</em> distribution or
619 modification of a work is allowed without an explicit
620 notice saying so. Therefore a program without a copyright
621 notice <em>is</em> copyrighted and you may not do anything
622 to it without risking being sued! Likewise if a program
623 has a copyright notice but no statement saying what is
624 permitted then nothing is permitted.
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <sect id="subsections">
649 <heading>Sections</heading>
652 The packages in the archive areas <em>main</em>,
653 <em>contrib</em> and <em>non-free</em> are grouped further into
654 <em>sections</em> to simplify handling.
658 The archive area and section for each package should be
659 specified in the package's <tt>Section</tt> control record (see
660 <ref id="f-Section">). However, the maintainer of the Debian
661 archive may override this selection to ensure the consistency of
662 the Debian distribution. The <tt>Section</tt> field should be
664 <list compact="compact">
666 <em>section</em> if the package is in the
667 <em>main</em> archive area,
670 <em>area/section</em> if the package is in
671 the <em>contrib</em> or <em>non-free</em>
678 The Debian archive maintainers provide the authoritative
679 list of sections. At present, they are:
680 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
681 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
682 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
683 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
684 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
685 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
686 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
687 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
688 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
689 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
690 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
691 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
692 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
697 <sect id="priorities">
698 <heading>Priorities</heading>
701 Each package should have a <em>priority</em> value, which is
702 included in the package's <em>control record</em>
703 (see <ref id="f-Priority">).
704 This information is used by the Debian package management tools to
705 separate high-priority packages from less-important packages.
709 The following <em>priority levels</em> are recognized by the
710 Debian package management tools.
712 <tag><tt>required</tt></tag>
714 Packages which are necessary for the proper
715 functioning of the system (usually, this means that
716 dpkg functionality depends on these packages).
717 Removing a <tt>required</tt> package may cause your
718 system to become totally broken and you may not even
719 be able to use <prgn>dpkg</prgn> to put things back,
720 so only do so if you know what you are doing. Systems
721 with only the <tt>required</tt> packages are probably
722 unusable, but they do have enough functionality to
723 allow the sysadmin to boot and install more software.
725 <tag><tt>important</tt></tag>
727 Important programs, including those which one would
728 expect to find on any Unix-like system. If the
729 expectation is that an experienced Unix person who
730 found it missing would say "What on earth is going on,
731 where is <prgn>foo</prgn>?", it must be an
732 <tt>important</tt> package.<footnote>
733 This is an important criterion because we are
734 trying to produce, amongst other things, a free
737 Other packages without which the system will not run
738 well or be usable must also have priority
739 <tt>important</tt>. This does
740 <em>not</em> include Emacs, the X Window System, TeX
741 or any other large applications. The
742 <tt>important</tt> packages are just a bare minimum of
743 commonly-expected and necessary tools.
745 <tag><tt>standard</tt></tag>
747 These packages provide a reasonably small but not too
748 limited character-mode system. This is what will be
749 installed by default if the user doesn't select anything
750 else. It doesn't include many large applications.
752 <tag><tt>optional</tt></tag>
754 (In a sense everything that isn't required is
755 optional, but that's not what is meant here.) This is
756 all the software that you might reasonably want to
757 install if you didn't know what it was and don't have
758 specialized requirements. This is a much larger system
759 and includes the X Window System, a full TeX
760 distribution, and many applications. Note that
761 optional packages should not conflict with each other.
763 <tag><tt>extra</tt></tag>
765 This contains all packages that conflict with others
766 with required, important, standard or optional
767 priorities, or are only likely to be useful if you
768 already know what they are or have specialized
769 requirements (such as packages containing only detached
776 Packages must not depend on packages with lower priority
777 values (excluding build-time dependencies). In order to
778 ensure this, the priorities of one or more packages may need
787 <heading>Binary packages</heading>
790 The Debian GNU/Linux distribution is based on the Debian
791 package management system, called <prgn>dpkg</prgn>. Thus,
792 all packages in the Debian distribution must be provided
793 in the <tt>.deb</tt> file format.
797 <heading>The package name</heading>
800 Every package must have a name that's unique within the Debian
805 The package name is included in the control field
806 <tt>Package</tt>, the format of which is described
807 in <ref id="f-Package">.
808 The package name is also included as a part of the file name
809 of the <tt>.deb</tt> file.
814 <heading>The version of a package</heading>
817 Every package has a version number recorded in its
818 <tt>Version</tt> control file field, described in
819 <ref id="f-Version">.
823 The package management system imposes an ordering on version
824 numbers, so that it can tell whether packages are being up- or
825 downgraded and so that package system front end applications
826 can tell whether a package it finds available is newer than
827 the one installed on the system. The version number format
828 has the most significant parts (as far as comparison is
829 concerned) at the beginning.
833 If an upstream package has problematic version numbers they
834 should be converted to a sane form for use in the
835 <tt>Version</tt> field.
839 <heading>Version numbers based on dates</heading>
842 In general, Debian packages should use the same version
843 numbers as the upstream sources.
847 However, in some cases where the upstream version number is
848 based on a date (e.g., a development "snapshot" release) the
849 package management system cannot handle these version
850 numbers without epochs. For example, dpkg will consider
851 "96May01" to be greater than "96Dec24".
855 To prevent having to use epochs for every new upstream
856 version, the date based portion of the version number
857 should be changed to the following format in such cases:
858 "19960501", "19961224". It is up to the maintainer whether
859 they want to bother the upstream maintainer to change
860 the version numbers upstream, too.
864 Note that other version formats based on dates which are
865 parsed correctly by the package management system should
866 <em>not</em> be changed.
870 Native Debian packages (i.e., packages which have been
871 written especially for Debian) whose version numbers include
872 dates should always use the "YYYYMMDD" format.
879 <heading>The maintainer of a package</heading>
882 Every package must have a Debian maintainer (the
883 maintainer may be one person or a group of people
884 reachable from a common email address, such as a mailing
885 list). The maintainer is responsible for ensuring that
886 the package is placed in the appropriate distributions.
890 The maintainer must be specified in the
891 <tt>Maintainer</tt> control field with their correct name
892 and a working email address. If one person maintains
893 several packages, they should try to avoid having
894 different forms of their name and email address in
895 the <tt>Maintainer</tt> fields of those packages.
899 The format of the <tt>Maintainer</tt> control field is
900 described in <ref id="f-Maintainer">.
904 If the maintainer of a package quits from the Debian
905 project, "Debian QA Group"
906 <email>packages@qa.debian.org</email> takes over the
907 maintainer-ship of the package until someone else
908 volunteers for that task. These packages are called
909 <em>orphaned packages</em>.<footnote>
910 The detailed procedure for doing this gracefully can
911 be found in the Debian Developer's Reference,
912 see <ref id="related">.
917 <sect id="descriptions">
918 <heading>The description of a package</heading>
921 Every Debian package must have an extended description
922 stored in the appropriate field of the control record.
923 The technical information about the format of the
924 <tt>Description</tt> field is in <ref id="f-Description">.
928 The description should describe the package (the program) to a
929 user (system administrator) who has never met it before so that
930 they have enough information to decide whether they want to
931 install it. This description should not just be copied verbatim
932 from the program's documentation.
936 Put important information first, both in the synopsis and
937 extended description. Sometimes only the first part of the
938 synopsis or of the description will be displayed. You can
939 assume that there will usually be a way to see the whole
940 extended description.
944 The description should also give information about the
945 significant dependencies and conflicts between this package
946 and others, so that the user knows why these dependencies and
947 conflicts have been declared.
951 Instructions for configuring or using the package should
952 not be included (that is what installation scripts,
953 manual pages, info files, etc., are for). Copyright
954 statements and other administrivia should not be included
955 either (that is what the copyright file is for).
958 <sect1 id="synopsis"><heading>The single line synopsis</heading>
961 The single line synopsis should be kept brief - certainly
966 Do not include the package name in the synopsis line. The
967 display software knows how to display this already, and you
968 do not need to state it. Remember that in many situations
969 the user may only see the synopsis line - make it as
970 informative as you can.
975 <sect1 id="extendeddesc"><heading>The extended description</heading>
978 Do not try to continue the single line synopsis into the
979 extended description. This will not work correctly when
980 the full description is displayed, and makes no sense
981 where only the summary (the single line synopsis) is
986 The extended description should describe what the package
987 does and how it relates to the rest of the system (in terms
988 of, for example, which subsystem it is which part of).
992 The description field needs to make sense to anyone, even
993 people who have no idea about any of the things the
994 package deals with.<footnote>
995 The blurb that comes with a program in its
996 announcements and/or <prgn>README</prgn> files is
997 rarely suitable for use in a description. It is
998 usually aimed at people who are already in the
999 community where the package is used.
1008 <heading>Dependencies</heading>
1011 Every package must specify the dependency information
1012 about other packages that are required for the first to
1017 For example, a dependency entry must be provided for any
1018 shared libraries required by a dynamically-linked executable
1019 binary in a package.
1023 Packages are not required to declare any dependencies they
1024 have on other packages which are marked <tt>Essential</tt>
1025 (see below), and should not do so unless they depend on a
1026 particular version of that package.<footnote>
1028 Essential is needed in part to avoid unresolvable dependency
1029 loops on upgrade. If packages add unnecessary dependencies
1030 on packages in this set, the chances that there
1031 <strong>will</strong> be an unresolvable dependency loop
1032 caused by forcing these Essential packages to be configured
1033 first before they need to be is greatly increased. It also
1034 increases the chances that frontends will be unable to
1035 <strong>calculate</strong> an upgrade path, even if one
1039 Also, functionality is rarely ever removed from the
1040 Essential set, but <em>packages</em> have been removed from
1041 the Essential set when the functionality moved to a
1042 different package. So depending on these packages <em>just
1043 in case</em> they stop being essential does way more harm
1050 Sometimes, a package requires another package to be installed
1051 <em>and</em> configured before it can be installed. In this
1052 case, you must specify a <tt>Pre-Depends</tt> entry for
1057 You should not specify a <tt>Pre-Depends</tt> entry for a
1058 package before this has been discussed on the
1059 <tt>debian-devel</tt> mailing list and a consensus about
1060 doing that has been reached.
1064 The format of the package interrelationship control fields is
1065 described in <ref id="relationships">.
1069 <sect id="virtual_pkg">
1070 <heading>Virtual packages</heading>
1073 Sometimes, there are several packages which offer
1074 more-or-less the same functionality. In this case, it's
1075 useful to define a <em>virtual package</em> whose name
1076 describes that common functionality. (The virtual
1077 packages only exist logically, not physically; that's why
1078 they are called <em>virtual</em>.) The packages with this
1079 particular function will then <em>provide</em> the virtual
1080 package. Thus, any other package requiring that function
1081 can simply depend on the virtual package without having to
1082 specify all possible packages individually.
1086 All packages should use virtual package names where
1087 appropriate, and arrange to create new ones if necessary.
1088 They should not use virtual package names (except privately,
1089 amongst a cooperating group of packages) unless they have
1090 been agreed upon and appear in the list of virtual package
1091 names. (See also <ref id="virtual">)
1095 The latest version of the authoritative list of virtual
1096 package names can be found in the <tt>debian-policy</tt> package.
1097 It is also available from the Debian web mirrors at
1098 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1099 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1103 The procedure for updating the list is described in the preface
1110 <heading>Base system</heading>
1113 The <tt>base system</tt> is a minimum subset of the Debian
1114 GNU/Linux system that is installed before everything else
1115 on a new system. Only very few packages are allowed to form
1116 part of the base system, in order to keep the required disk
1121 The base system consists of all those packages with priority
1122 <tt>required</tt> or <tt>important</tt>. Many of them will
1123 be tagged <tt>essential</tt> (see below).
1128 <heading>Essential packages</heading>
1131 Essential is defined as the minimal set of functionality that
1132 must be available and usable on the system at all times, even
1133 when packages are in an unconfigured (but unpacked) state.
1134 Packages are tagged <tt>essential</tt> for a system using the
1135 <tt>Essential</tt> control file field. The format of the
1136 <tt>Essential</tt> control field is described in <ref
1141 Since these packages cannot be easily removed (one has to
1142 specify an extra <em>force option</em> to
1143 <prgn>dpkg</prgn> to do so), this flag must not be used
1144 unless absolutely necessary. A shared library package
1145 must not be tagged <tt>essential</tt>; dependencies will
1146 prevent its premature removal, and we need to be able to
1147 remove it when it has been superseded.
1151 Since dpkg will not prevent upgrading of other packages
1152 while an <tt>essential</tt> package is in an unconfigured
1153 state, all <tt>essential</tt> packages must supply all of
1154 their core functionality even when unconfigured. If the
1155 package cannot satisfy this requirement it must not be
1156 tagged as essential, and any packages depending on this
1157 package must instead have explicit dependency fields as
1162 Maintainers should take great care in adding any programs,
1163 interfaces, or functionality to <tt>essential</tt> packages.
1164 Packages may assume that functionality provided by
1165 <tt>essential</tt> packages is always available without
1166 declaring explicit dependencies, which means that removing
1167 functionality from the Essential set is very difficult and is
1168 almost never done. Any capability added to an
1169 <tt>essential</tt> package therefore creates an obligation to
1170 support that capability as part of the Essential set in
1175 You must not tag any packages <tt>essential</tt> before
1176 this has been discussed on the <tt>debian-devel</tt>
1177 mailing list and a consensus about doing that has been
1182 <sect id="maintscripts">
1183 <heading>Maintainer Scripts</heading>
1186 The package installation scripts should avoid producing
1187 output which is unnecessary for the user to see and
1188 should rely on <prgn>dpkg</prgn> to stave off boredom on
1189 the part of a user installing many packages. This means,
1190 amongst other things, using the <tt>--quiet</tt> option on
1191 <prgn>install-info</prgn>.
1195 Errors which occur during the execution of an installation
1196 script must be checked and the installation must not
1197 continue after an error.
1201 Note that in general <ref id="scripts"> applies to package
1202 maintainer scripts, too.
1206 You should not use <prgn>dpkg-divert</prgn> on a file
1207 belonging to another package without consulting the
1208 maintainer of that package first.
1212 All packages which supply an instance of a common command
1213 name (or, in general, filename) should generally use
1214 <prgn>update-alternatives</prgn>, so that they may be
1215 installed together. If <prgn>update-alternatives</prgn>
1216 is not used, then each package must use
1217 <tt>Conflicts</tt> to ensure that other packages are
1218 de-installed. (In this case, it may be appropriate to
1219 specify a conflict against earlier versions of something
1220 that previously did not use
1221 <prgn>update-alternatives</prgn>; this is an exception to
1222 the usual rule that versioned conflicts should be
1226 <sect1 id="maintscriptprompt">
1227 <heading>Prompting in maintainer scripts</heading>
1229 Package maintainer scripts may prompt the user if
1230 necessary. Prompting must be done by communicating
1231 through a program, such as <prgn>debconf</prgn>, which
1232 conforms to the Debian Configuration Management
1233 Specification, version 2 or higher.
1237 Packages which are essential, or which are dependencies of
1238 essential packages, may fall back on another prompting method
1239 if no such interface is available when they are executed.
1243 The Debian Configuration Management Specification is included
1244 in the <file>debconf_specification</file> files in the
1245 <package>debian-policy</package> package.
1246 It is also available from the Debian web mirrors at
1247 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1248 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1252 Packages which use the Debian Configuration Management
1253 Specification may contain an additional
1254 <prgn>config</prgn> script and a <tt>templates</tt>
1255 file in their control archive<footnote>
1256 The control.tar.gz inside the .deb.
1257 See <manref name="deb" section="5">.
1259 The <prgn>config</prgn> script might be run before the
1260 <prgn>preinst</prgn> script, and before the package is unpacked
1261 or any of its dependencies or pre-dependencies are satisfied.
1262 Therefore it must work using only the tools present in
1263 <em>essential</em> packages.<footnote>
1264 <package>Debconf</package> or another tool that
1265 implements the Debian Configuration Management
1266 Specification will also be installed, and any
1267 versioned dependencies on it will be satisfied
1268 before preconfiguration begins.
1273 Packages which use the Debian Configuration Management
1274 Specification must allow for translation of their user-visible
1275 messages by using a gettext-based system such as the one
1276 provided by the <package>po-debconf</package> package.
1280 Packages should try to minimize the amount of prompting
1281 they need to do, and they should ensure that the user
1282 will only ever be asked each question once. This means
1283 that packages should try to use appropriate shared
1284 configuration files (such as <file>/etc/papersize</file> and
1285 <file>/etc/news/server</file>), and shared
1286 <package>debconf</package> variables rather than each
1287 prompting for their own list of required pieces of
1292 It also means that an upgrade should not ask the same
1293 questions again, unless the user has used
1294 <tt>dpkg --purge</tt> to remove the package's configuration.
1295 The answers to configuration questions should be stored in an
1296 appropriate place in <file>/etc</file> so that the user can
1297 modify them, and how this has been done should be
1302 If a package has a vitally important piece of
1303 information to pass to the user (such as "don't run me
1304 as I am, you must edit the following configuration files
1305 first or you risk your system emitting badly-formatted
1306 messages"), it should display this in the
1307 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1308 prompt the user to hit return to acknowledge the
1309 message. Copyright messages do not count as vitally
1310 important (they belong in
1311 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1312 neither do instructions on how to use a program (these
1313 should be in on-line documentation, where all the users
1318 Any necessary prompting should almost always be confined
1319 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1320 script. If it is done in the <prgn>postinst</prgn>, it
1321 should be protected with a conditional so that
1322 unnecessary prompting doesn't happen if a package's
1323 installation fails and the <prgn>postinst</prgn> is
1324 called with <tt>abort-upgrade</tt>,
1325 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1335 <heading>Source packages</heading>
1337 <sect id="standardsversion">
1338 <heading>Standards conformance</heading>
1341 Source packages should specify the most recent version number
1342 of this policy document with which your package complied
1343 when it was last updated.
1347 This information may be used to file bug reports
1348 automatically if your package becomes too much out of date.
1352 The version is specified in the <tt>Standards-Version</tt>
1354 The format of the <tt>Standards-Version</tt> field is
1355 described in <ref id="f-Standards-Version">.
1359 You should regularly, and especially if your package has
1360 become out of date, check for the newest Policy Manual
1361 available and update your package, if necessary. When your
1362 package complies with the new standards you should update the
1363 <tt>Standards-Version</tt> source package field and
1364 release it.<footnote>
1365 See the file <file>upgrading-checklist</file> for
1366 information about policy which has changed between
1367 different versions of this document.
1373 <sect id="pkg-relations">
1374 <heading>Package relationships</heading>
1377 Source packages should specify which binary packages they
1378 require to be installed or not to be installed in order to
1379 build correctly. For example, if building a package
1380 requires a certain compiler, then the compiler should be
1381 specified as a build-time dependency.
1385 It is not necessary to explicitly specify build-time
1386 relationships on a minimal set of packages that are always
1387 needed to compile, link and put in a Debian package a
1388 standard "Hello World!" program written in C or C++. The
1389 required packages are called <em>build-essential</em>, and
1390 an informational list can be found in
1391 <file>/usr/share/doc/build-essential/list</file> (which is
1392 contained in the <tt>build-essential</tt>
1395 <list compact="compact">
1397 This allows maintaining the list separately
1398 from the policy documents (the list does not
1399 need the kind of control that the policy
1403 Having a separate package allows one to install
1404 the build-essential packages on a machine, as
1405 well as allowing other packages such as tasks to
1406 require installation of the build-essential
1407 packages using the depends relation.
1410 The separate package allows bug reports against
1411 the list to be categorized separately from
1412 the policy management process in the BTS.
1419 When specifying the set of build-time dependencies, one
1420 should list only those packages explicitly required by the
1421 build. It is not necessary to list packages which are
1422 required merely because some other package in the list of
1423 build-time dependencies depends on them.<footnote>
1424 The reason for this is that dependencies change, and
1425 you should list all those packages, and <em>only</em>
1426 those packages that <em>you</em> need directly. What
1427 others need is their business. For example, if you
1428 only link against <file>libimlib</file>, you will need to
1429 build-depend on <package>libimlib2-dev</package> but
1430 not against any <tt>libjpeg*</tt> packages, even
1431 though <tt>libimlib2-dev</tt> currently depends on
1432 them: installation of <package>libimlib2-dev</package>
1433 will automatically ensure that all of its run-time
1434 dependencies are satisfied.
1439 If build-time dependencies are specified, it must be
1440 possible to build the package and produce working binaries
1441 on a system with only essential and build-essential
1442 packages installed and also those required to satisfy the
1443 build-time relationships (including any implied
1444 relationships). In particular, this means that version
1445 clauses should be used rigorously in build-time
1446 relationships so that one cannot produce bad or
1447 inconsistently configured packages when the relationships
1448 are properly satisfied.
1452 <ref id="relationships"> explains the technical details.
1457 <heading>Changes to the upstream sources</heading>
1460 If changes to the source code are made that are not
1461 specific to the needs of the Debian system, they should be
1462 sent to the upstream authors in whatever form they prefer
1463 so as to be included in the upstream version of the
1468 If you need to configure the package differently for
1469 Debian or for Linux, and the upstream source doesn't
1470 provide a way to do so, you should add such configuration
1471 facilities (for example, a new <prgn>autoconf</prgn> test
1472 or <tt>#define</tt>) and send the patch to the upstream
1473 authors, with the default set to the way they originally
1474 had it. You can then easily override the default in your
1475 <file>debian/rules</file> or wherever is appropriate.
1479 You should make sure that the <prgn>configure</prgn> utility
1480 detects the correct architecture specification string
1481 (refer to <ref id="arch-spec"> for details).
1485 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1486 <prgn>configure</prgn> scripts are used, you should edit the
1487 <file>.in</file> files rather than editing the
1488 <prgn>Makefile</prgn> directly. This allows the user to
1489 reconfigure the package if necessary. You should
1490 <em>not</em> configure the package and edit the generated
1491 <prgn>Makefile</prgn>! This makes it impossible for someone
1492 else to later reconfigure the package without losing the
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>.<footnote>
1506 Mistakes in changelogs are usually best rectified by
1507 making a new changelog entry rather than "rewriting
1508 history" by editing old changelog entries.
1511 This includes modifications
1512 made in the Debian package compared to the upstream one
1513 as well as other changes and updates to the package.
1515 Although there is nothing stopping an author who is also
1516 the Debian maintainer from using this changelog for all
1517 their changes, it will have to be renamed if the Debian
1518 and upstream maintainers become different people. In such
1519 a case, however, it might be better to maintain the package
1520 as a non-native package.
1525 The format of the <file>debian/changelog</file> allows the
1526 package building tools to discover which version of the package
1527 is being built and find out other release-specific information.
1531 That format is a series of entries like this:
1533 <example compact="compact">
1534 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1536 [optional blank line(s), stripped]
1538 * <var>change details</var>
1539 <var>more change details</var>
1541 [blank line(s), included in output of dpkg-parsechangelog]
1543 * <var>even more change details</var>
1545 [optional blank line(s), stripped]
1547 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1552 <var>package</var> and <var>version</var> are the source
1553 package name and version number.
1557 <var>distribution(s)</var> lists the distributions where
1558 this version should be installed when it is uploaded - it
1559 is copied to the <tt>Distribution</tt> field in the
1560 <file>.changes</file> file. See <ref id="f-Distribution">.
1564 <var>urgency</var> is the value for the <tt>Urgency</tt>
1565 field in the <file>.changes</file> file for the upload
1566 (see <ref id="f-Urgency">). It is not possible to specify
1567 an urgency containing commas; commas are used to separate
1568 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1569 <prgn>dpkg</prgn> changelog format (though there is
1570 currently only one useful <var>keyword</var>,
1575 The change details may in fact be any series of lines
1576 starting with at least two spaces, but conventionally each
1577 change starts with an asterisk and a separating space and
1578 continuation lines are indented so as to bring them in
1579 line with the start of the text above. Blank lines may be
1580 used here to separate groups of changes, if desired.
1584 If this upload resolves bugs recorded in the Bug Tracking
1585 System (BTS), they may be automatically closed on the
1586 inclusion of this package into the Debian archive by
1587 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1588 in the change details.<footnote>
1589 To be precise, the string should match the following
1590 Perl regular expression:
1592 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1594 Then all of the bug numbers listed will be closed by the
1595 archive maintenance script (<prgn>katie</prgn>) using the
1596 <var>version</var> of the changelog entry.
1598 This information is conveyed via the <tt>Closes</tt> field
1599 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1603 The maintainer name and email address used in the changelog
1604 should be the details of the person uploading <em>this</em>
1605 version. They are <em>not</em> necessarily those of the
1606 usual package maintainer. The information here will be
1607 copied to the <tt>Changed-By</tt> field in the
1608 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1609 and then later used to send an acknowledgement when the
1610 upload has been installed.
1614 The <var>date</var> must be in RFC822 format<footnote>
1615 This is generated by <tt>date -R</tt>.
1616 </footnote>; it must include the time zone specified
1617 numerically, with the time zone name or abbreviation
1618 optionally present as a comment in parentheses.
1622 The first "title" line with the package name must start
1623 at the left hand margin. The "trailer" line with the
1624 maintainer and date details must be preceded by exactly
1625 one space. The maintainer details and the date must be
1626 separated by exactly two spaces.
1630 The entire changelog must be encoded in UTF-8.
1634 For more information on placement of the changelog files
1635 within binary packages, please see <ref id="changelogs">.
1639 <sect id="dpkgcopyright">
1640 <heading>Copyright: <file>debian/copyright</file></heading>
1642 Every package must be accompanied by a verbatim copy of
1643 its copyright and distribution license in the file
1644 <file>/usr/share/doc/<var>package</var>/copyright</file>
1645 (see <ref id="copyrightfile"> for further details). Also see
1646 <ref id="pkgcopyright"> for further considerations related
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">.
2732 An architecture wildcard identifying a set of Debian
2733 machine architectures, see <ref id="arch-wildcard-spec">.
2735 <item><tt>all</tt>, which indicates an
2736 architecture-independent package.
2737 <item><tt>any</tt>, which indicates a package available
2738 for building on any architecture.
2739 <item><tt>source</tt>, which indicates a source package.
2744 In the main <file>debian/control</file> file in the source
2745 package, this field may contain the special value
2746 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2747 specific and wildcard architectures separated by
2748 spaces. If the special value <tt>any</tt> appears, it must
2749 be the entire contents of the field. Most packages will
2750 use either <tt>any</tt> or <tt>all</tt>. Specifying a
2751 specific list of architectures is for the minority of
2752 cases where a program is not portable or is not useful on
2753 some architectures, and where possible the program should
2754 be made portable instead.
2758 In the source package control file <file>.dsc</file>, this
2759 field may contain either the special value <tt>any</tt> or a
2760 list of architectures separated by spaces. If a list is given,
2761 it may include (or consist solely of) the special value
2762 <tt>all</tt>. In other words, in <file>.dsc</file> files
2763 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2764 in combination with specific architectures. The
2765 <tt>Architecture</tt> field in the source package control file
2766 <file>.dsc</file> is generally constructed from the
2767 <tt>Architecture</tt> fields in the
2768 <file>debian/control</file> in the source package.
2772 Specifying <tt>any</tt> indicates that the source package
2773 isn't dependent on any particular architecture and should
2774 compile fine on any one. The produced binary package(s)
2775 will either be specific to whatever the current build
2776 architecture is or will be architecture-independent.
2780 Specifying only <tt>all</tt> indicates that the source package
2781 will only build architecture-independent packages. If this is
2782 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2783 <tt>any</tt> implies that the source package will build at
2784 least one architecture-dependent package.
2788 Specifying a list of architectures indicates that the source
2789 will build an architecture-dependent package, and will only
2790 work correctly on the listed architectures. If the source
2791 package also builds at least one architecture-independent
2792 package, <tt>all</tt> will also be included in the list.
2796 Specifying a list of architecture wildcards indicates that
2797 the source will build an architecture-dependent package on
2798 the union of the lists of architectures from the expansion
2799 of each specified architecture wildcard, and will only
2800 work correctly on the architectures in the union of the
2801 lists.<footnote> As mentioned in the footnote for
2802 specifying a list of architectures, this is for a minority
2803 of cases where the program is not portable. Generally, it
2804 should not be used for new packages. Wildcards are not
2805 expanded into a list of known architectures before
2806 comparing to the build architecutre. Instead, the build
2807 architecture is matched against wildcards and this package
2808 is built if the wildcard matches.</footnote> If the source
2809 package also builds at least one architecture-independent
2810 package, <tt>all</tt> will also be included in the list.
2814 In a <file>.changes</file> file, the <tt>Architecture</tt>
2815 field lists the architecture(s) of the package(s)
2816 currently being uploaded. This will be a list; if the
2817 source for the package is also being uploaded, the special
2818 entry <tt>source</tt> is also present. <tt>all</tt> will be
2819 present if any architecture-independent packages are being
2820 uploaded. <tt>any</tt> may never occur in the
2821 <tt>Architecture</tt> field in the <file>.changes</file>
2826 See <ref id="debianrules"> for information how to get the
2827 architecture for the build process.
2831 <sect1 id="f-Essential">
2832 <heading><tt>Essential</tt></heading>
2835 This is a boolean field which may occur only in the
2836 control file of a binary package or in a per-package fields
2837 paragraph of a main source control data file.
2841 If set to <tt>yes</tt> then the package management system
2842 will refuse to remove the package (upgrading and replacing
2843 it is still possible). The other possible value is <tt>no</tt>,
2844 which is the same as not having the field at all.
2849 <heading>Package interrelationship fields:
2850 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2851 <tt>Recommends</tt>, <tt>Suggests</tt>,
2852 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2853 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2857 These fields describe the package's relationships with
2858 other packages. Their syntax and semantics are described
2859 in <ref id="relationships">.</p>
2862 <sect1 id="f-Standards-Version">
2863 <heading><tt>Standards-Version</tt></heading>
2866 The most recent version of the standards (the policy
2867 manual and associated texts) with which the package
2872 The version number has four components: major and minor
2873 version number and major and minor patch level. When the
2874 standards change in a way that requires every package to
2875 change the major number will be changed. Significant
2876 changes that will require work in many packages will be
2877 signaled by a change to the minor number. The major patch
2878 level will be changed for any change to the meaning of the
2879 standards, however small; the minor patch level will be
2880 changed when only cosmetic, typographical or other edits
2881 are made which neither change the meaning of the document
2882 nor affect the contents of packages.
2886 Thus only the first three components of the policy version
2887 are significant in the <em>Standards-Version</em> control
2888 field, and so either these three components or the all
2889 four components may be specified.<footnote>
2890 In the past, people specified the full version number
2891 in the Standards-Version field, for example "2.3.0.0".
2892 Since minor patch-level changes don't introduce new
2893 policy, it was thought it would be better to relax
2894 policy and only require the first 3 components to be
2895 specified, in this example "2.3.0". All four
2896 components may still be used if someone wishes to do so.
2902 <sect1 id="f-Version">
2903 <heading><tt>Version</tt></heading>
2906 The version number of a package. The format is:
2907 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2911 The three components here are:
2913 <tag><var>epoch</var></tag>
2916 This is a single (generally small) unsigned integer. It
2917 may be omitted, in which case zero is assumed. If it is
2918 omitted then the <var>upstream_version</var> may not
2923 It is provided to allow mistakes in the version numbers
2924 of older versions of a package, and also a package's
2925 previous version numbering schemes, to be left behind.
2929 <tag><var>upstream_version</var></tag>
2932 This is the main part of the version number. It is
2933 usually the version number of the original ("upstream")
2934 package from which the <file>.deb</file> file has been made,
2935 if this is applicable. Usually this will be in the same
2936 format as that specified by the upstream author(s);
2937 however, it may need to be reformatted to fit into the
2938 package management system's format and comparison
2943 The comparison behavior of the package management system
2944 with respect to the <var>upstream_version</var> is
2945 described below. The <var>upstream_version</var>
2946 portion of the version number is mandatory.
2950 The <var>upstream_version</var> may contain only
2951 alphanumerics<footnote>
2952 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2954 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2955 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2956 tilde) and should start with a digit. If there is no
2957 <var>debian_revision</var> then hyphens are not allowed;
2958 if there is no <var>epoch</var> then colons are not
2963 <tag><var>debian_revision</var></tag>
2966 This part of the version number specifies the version of
2967 the Debian package based on the upstream version. It
2968 may contain only alphanumerics and the characters
2969 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2970 tilde) and is compared in the same way as the
2971 <var>upstream_version</var> is.
2975 It is optional; if it isn't present then the
2976 <var>upstream_version</var> may not contain a hyphen.
2977 This format represents the case where a piece of
2978 software was written specifically to be turned into a
2979 Debian package, and so there is only one "debianisation"
2980 of it and therefore no revision indication is required.
2984 It is conventional to restart the
2985 <var>debian_revision</var> at <tt>1</tt> each time the
2986 <var>upstream_version</var> is increased.
2990 The package management system will break the version
2991 number apart at the last hyphen in the string (if there
2992 is one) to determine the <var>upstream_version</var> and
2993 <var>debian_revision</var>. The absence of a
2994 <var>debian_revision</var> is equivalent to a
2995 <var>debian_revision</var> of <tt>0</tt>.
3002 When comparing two version numbers, first the <var>epoch</var>
3003 of each are compared, then the <var>upstream_version</var> if
3004 <var>epoch</var> is equal, and then <var>debian_revision</var>
3005 if <var>upstream_version</var> is also equal.
3006 <var>epoch</var> is compared numerically. The
3007 <var>upstream_version</var> and <var>debian_revision</var>
3008 parts are compared by the package management system using the
3009 following algorithm:
3013 The strings are compared from left to right.
3017 First the initial part of each string consisting entirely of
3018 non-digit characters is determined. These two parts (one of
3019 which may be empty) are compared lexically. If a difference
3020 is found it is returned. The lexical comparison is a
3021 comparison of ASCII values modified so that all the letters
3022 sort earlier than all the non-letters and so that a tilde
3023 sorts before anything, even the end of a part. For example,
3024 the following parts are in sorted order from earliest to
3025 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3026 <tt>a</tt>.<footnote>
3027 One common use of <tt>~</tt> is for upstream pre-releases.
3028 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3029 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3034 Then the initial part of the remainder of each string which
3035 consists entirely of digit characters is determined. The
3036 numerical values of these two parts are compared, and any
3037 difference found is returned as the result of the comparison.
3038 For these purposes an empty string (which can only occur at
3039 the end of one or both version strings being compared) counts
3044 These two steps (comparing and removing initial non-digit
3045 strings and initial digit strings) are repeated until a
3046 difference is found or both strings are exhausted.
3050 Note that the purpose of epochs is to allow us to leave behind
3051 mistakes in version numbering, and to cope with situations
3052 where the version numbering scheme changes. It is
3053 <em>not</em> intended to cope with version numbers containing
3054 strings of letters which the package management system cannot
3055 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3056 silly orderings (the author of this manual has heard of a
3057 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3058 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3059 <tt>2</tt> and so forth).
3063 <sect1 id="f-Description">
3064 <heading><tt>Description</tt></heading>
3067 In a source or binary control file, the <tt>Description</tt>
3068 field contains a description of the binary package, consisting
3069 of two parts, the synopsis or the short description, and the
3070 long description. The field's format is as follows:
3075 Description: <single line synopsis>
3076 <extended description over several lines>
3081 The lines in the extended description can have these formats:
3087 Those starting with a single space are part of a paragraph.
3088 Successive lines of this form will be word-wrapped when
3089 displayed. The leading space will usually be stripped off.
3093 Those starting with two or more spaces. These will be
3094 displayed verbatim. If the display cannot be panned
3095 horizontally, the displaying program will line wrap them "hard"
3096 (i.e., without taking account of word breaks). If it can they
3097 will be allowed to trail off to the right. None, one or two
3098 initial spaces may be deleted, but the number of spaces
3099 deleted from each line will be the same (so that you can have
3100 indenting work correctly, for example).
3104 Those containing a single space followed by a single full stop
3105 character. These are rendered as blank lines. This is the
3106 <em>only</em> way to get a blank line<footnote>
3107 Completely empty lines will not be rendered as blank lines.
3108 Instead, they will cause the parser to think you're starting
3109 a whole new record in the control file, and will therefore
3110 likely abort with an error.
3115 Those containing a space, a full stop and some more characters.
3116 These are for future expansion. Do not use them.
3122 Do not use tab characters. Their effect is not predictable.
3126 See <ref id="descriptions"> for further information on this.
3130 In a <file>.changes</file> file, the <tt>Description</tt>
3131 field contains a summary of the descriptions for the packages
3132 being uploaded. For this case, the first line of the field
3133 value (the part on the same line as <tt>Description:</tt>) is
3134 always empty. The content of the field is expressed as
3135 continuation lines, one line per package. Each line is
3136 indented by one space and contains the name of a binary
3137 package, a space, a hyphen (<tt>-</tt>), a space, and the
3138 short description line from that package.
3142 <sect1 id="f-Distribution">
3143 <heading><tt>Distribution</tt></heading>
3146 In a <file>.changes</file> file or parsed changelog output
3147 this contains the (space-separated) name(s) of the
3148 distribution(s) where this version of the package should
3149 be installed. Valid distributions are determined by the
3150 archive maintainers.<footnote>
3151 Example distribution names in the Debian archive used in
3152 <file>.changes</file> files are:
3153 <taglist compact="compact">
3154 <tag><em>unstable</em></tag>
3156 This distribution value refers to the
3157 <em>developmental</em> part of the Debian distribution
3158 tree. Most new packages, new upstream versions of
3159 packages and bug fixes go into the <em>unstable</em>
3163 <tag><em>experimental</em></tag>
3165 The packages with this distribution value are deemed
3166 by their maintainers to be high risk. Oftentimes they
3167 represent early beta or developmental packages from
3168 various sources that the maintainers want people to
3169 try, but are not ready to be a part of the other parts
3170 of the Debian distribution tree.
3175 Others are used for updating stable releases or for
3176 security uploads. More information is available in the
3177 Debian Developer's Reference, section "The Debian
3181 The Debian archive software only supports listing a single
3182 distribution. Migration of packages to other distributions is
3183 handled outside of the upload process.
3188 <heading><tt>Date</tt></heading>
3191 This field includes the date the package was built or last edited.
3195 The value of this field is usually extracted from the
3196 <file>debian/changelog</file> file - see
3197 <ref id="dpkgchangelog">).
3201 <sect1 id="f-Format">
3202 <heading><tt>Format</tt></heading>
3205 This field specifies a format revision for the file.
3206 The most current format described in the Policy Manual
3207 is version <strong>1.5</strong>. The syntax of the
3208 format value is the same as that of a package version
3209 number except that no epoch or Debian revision is allowed
3210 - see <ref id="f-Version">.
3214 <sect1 id="f-Urgency">
3215 <heading><tt>Urgency</tt></heading>
3218 This is a description of how important it is to upgrade to
3219 this version from previous ones. It consists of a single
3220 keyword taking one of the values <tt>low</tt>,
3221 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3222 <tt>critical</tt><footnote>
3223 Other urgency values are supported with configuration
3224 changes in the archive software but are not used in Debian.
3225 The urgency affects how quickly a package will be considered
3226 for inclusion into the <tt>testing</tt> distribution and
3227 gives an indication of the importance of any fixes included
3228 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3229 treated as synonymous.
3230 </footnote> (not case-sensitive) followed by an optional
3231 commentary (separated by a space) which is usually in
3232 parentheses. For example:
3235 Urgency: low (HIGH for users of diversions)
3241 The value of this field is usually extracted from the
3242 <file>debian/changelog</file> file - see
3243 <ref id="dpkgchangelog">.
3247 <sect1 id="f-Changes">
3248 <heading><tt>Changes</tt></heading>
3251 This field contains the human-readable changes data, describing
3252 the differences between the last version and the current one.
3256 The first line of the field value (the part on the same line
3257 as <tt>Changes:</tt>) is always empty. The content of the
3258 field is expressed as continuation lines, with each line
3259 indented by at least one space. Blank lines must be
3260 represented by a line consisting only of a space and a full
3265 The value of this field is usually extracted from the
3266 <file>debian/changelog</file> file - see
3267 <ref id="dpkgchangelog">).
3271 Each version's change information should be preceded by a
3272 "title" line giving at least the version, distribution(s)
3273 and urgency, in a human-readable way.
3277 If data from several versions is being returned the entry
3278 for the most recent version should be returned first, and
3279 entries should be separated by the representation of a
3280 blank line (the "title" line may also be followed by the
3281 representation of blank line).
3285 <sect1 id="f-Binary">
3286 <heading><tt>Binary</tt></heading>
3289 This field is a list of binary packages. Its syntax and
3290 meaning varies depending on the control file in which it
3295 When it appears in the <file>.dsc</file> file, it lists binary
3296 packages which a source package can produce, separated by
3298 A space after each comma is conventional.
3299 </footnote>. It may span multiple lines. The source package
3300 does not necessarily produce all of these binary packages for
3301 every architecture. The source control file doesn't contain
3302 details of which architectures are appropriate for which of
3303 the binary packages.
3307 When it appears in a <file>.changes</file> file, it lists the
3308 names of the binary packages being uploaded, separated by
3309 whitespace (not commas). It may span multiple lines.
3313 <sect1 id="f-Installed-Size">
3314 <heading><tt>Installed-Size</tt></heading>
3317 This field appears in the control files of binary packages,
3318 and in the <file>Packages</file> files. It gives an estimate
3319 of the total amount of disk space required to install the
3320 named package. Actual installed size may vary based on block
3321 size, file system properties, or actions taken by package
3326 The disk space is given as the integer value of the estimated
3327 installed size in bytes, divided by 1024 and rounded up.
3331 <sect1 id="f-Files">
3332 <heading><tt>Files</tt></heading>
3335 This field contains a list of files with information about
3336 each one. The exact information and syntax varies with
3341 In all cases, Files is a multiline field. The first line of
3342 the field value (the part on the same line as <tt>Files:</tt>)
3343 is always empty. The content of the field is expressed as
3344 continuation lines, one line per file. Each line must be
3345 indented by one space and contain a number of sub-fields,
3346 separated by spaces, as described below.
3350 In the <file>.dsc</file> file, each line contains the MD5
3351 checksum, size and filename of the tar file and (if
3352 applicable) diff file which make up the remainder of the
3353 source package<footnote>
3354 That is, the parts which are not the <tt>.dsc</tt>.
3355 </footnote>. For example:
3358 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3359 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3361 The exact forms of the filenames are described
3362 in <ref id="pkg-sourcearchives">.
3366 In the <file>.changes</file> file this contains one line per
3367 file being uploaded. Each line contains the MD5 checksum,
3368 size, section and priority and the filename. For example:
3371 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3372 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3373 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3374 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3376 The <qref id="f-Section">section</qref>
3377 and <qref id="f-Priority">priority</qref> are the values of
3378 the corresponding fields in the main source control file. If
3379 no section or priority is specified then <tt>-</tt> should be
3380 used, though section and priority values must be specified for
3381 new packages to be installed properly.
3385 The special value <tt>byhand</tt> for the section in a
3386 <tt>.changes</tt> file indicates that the file in question
3387 is not an ordinary package file and must by installed by
3388 hand by the distribution maintainers. If the section is
3389 <tt>byhand</tt> the priority should be <tt>-</tt>.
3393 If a new Debian revision of a package is being shipped and
3394 no new original source archive is being distributed the
3395 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3396 entry for the original source archive
3397 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3398 but the <file>.changes</file> file should leave it out. In
3399 this case the original source archive on the distribution
3400 site must match exactly, byte-for-byte, the original
3401 source archive which was used to generate the
3402 <file>.dsc</file> file and diff which are being uploaded.</p>
3405 <sect1 id="f-Closes">
3406 <heading><tt>Closes</tt></heading>
3409 A space-separated list of bug report numbers that the upload
3410 governed by the .changes file closes.
3414 <sect1 id="f-Homepage">
3415 <heading><tt>Homepage</tt></heading>
3418 The URL of the web site for this package, preferably (when
3419 applicable) the site from which the original source can be
3420 obtained and any additional upstream documentation or
3421 information may be found. The content of this field is a
3422 simple URL without any surrounding characters such as
3430 <heading>User-defined fields</heading>
3433 Additional user-defined fields may be added to the
3434 source package control file. Such fields will be
3435 ignored, and not copied to (for example) binary or
3436 source package control files or upload control files.
3440 If you wish to add additional unsupported fields to
3441 these output files you should use the mechanism
3446 Fields in the main source control information file with
3447 names starting <tt>X</tt>, followed by one or more of
3448 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3449 be copied to the output files. Only the part of the
3450 field name after the hyphen will be used in the output
3451 file. Where the letter <tt>B</tt> is used the field
3452 will appear in binary package control files, where the
3453 letter <tt>S</tt> is used in source package control
3454 files and where <tt>C</tt> is used in upload control
3455 (<tt>.changes</tt>) files.
3459 For example, if the main source information control file
3462 XBS-Comment: I stand between the candle and the star.
3464 then the binary and source package control files will contain the
3467 Comment: I stand between the candle and the star.
3476 <chapt id="maintainerscripts">
3477 <heading>Package maintainer scripts and installation procedure</heading>
3480 <heading>Introduction to package maintainer scripts</heading>
3483 It is possible to supply scripts as part of a package which
3484 the package management system will run for you when your
3485 package is installed, upgraded or removed.
3489 These scripts are the files <prgn>preinst</prgn>,
3490 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3491 <prgn>postrm</prgn> in the control area of the package.
3492 They must be proper executable files; if they are scripts
3493 (which is recommended), they must start with the usual
3494 <tt>#!</tt> convention. They should be readable and
3495 executable by anyone, and must not be world-writable.
3499 The package management system looks at the exit status from
3500 these scripts. It is important that they exit with a
3501 non-zero status if there is an error, so that the package
3502 management system can stop its processing. For shell
3503 scripts this means that you <em>almost always</em> need to
3504 use <tt>set -e</tt> (this is usually true when writing shell
3505 scripts, in fact). It is also important, of course, that
3506 they exit with a zero status if everything went well.
3510 Additionally, packages interacting with users using
3511 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3512 install a <prgn>config</prgn> script in the control area,
3513 see <ref id="maintscriptprompt"> for details.
3517 When a package is upgraded a combination of the scripts from
3518 the old and new packages is called during the upgrade
3519 procedure. If your scripts are going to be at all
3520 complicated you need to be aware of this, and may need to
3521 check the arguments to your scripts.
3525 Broadly speaking the <prgn>preinst</prgn> is called before
3526 (a particular version of) a package is installed, and the
3527 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3528 before (a version of) a package is removed and the
3529 <prgn>postrm</prgn> afterwards.
3533 Programs called from maintainer scripts should not normally
3534 have a path prepended to them. Before installation is
3535 started, the package management system checks to see if the
3536 programs <prgn>ldconfig</prgn>,
3537 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3538 and <prgn>update-rc.d</prgn> can be found via the
3539 <tt>PATH</tt> environment variable. Those programs, and any
3540 other program that one would expect to be in the
3541 <tt>PATH</tt>, should thus be invoked without an absolute
3542 pathname. Maintainer scripts should also not reset the
3543 <tt>PATH</tt>, though they might choose to modify it by
3544 prepending or appending package-specific directories. These
3545 considerations really apply to all shell scripts.</p>
3548 <sect id="idempotency">
3549 <heading>Maintainer scripts idempotency</heading>
3552 It is necessary for the error recovery procedures that the
3553 scripts be idempotent. This means that if it is run
3554 successfully, and then it is called again, it doesn't bomb
3555 out or cause any harm, but just ensures that everything is
3556 the way it ought to be. If the first call failed, or
3557 aborted half way through for some reason, the second call
3558 should merely do the things that were left undone the first
3559 time, if any, and exit with a success status if everything
3561 This is so that if an error occurs, the user interrupts
3562 <prgn>dpkg</prgn> or some other unforeseen circumstance
3563 happens you don't leave the user with a badly-broken
3564 package when <prgn>dpkg</prgn> attempts to repeat the
3570 <sect id="controllingterminal">
3571 <heading>Controlling terminal for maintainer scripts</heading>
3574 The maintainer scripts are guaranteed to run with a
3575 controlling terminal and can interact with the user.
3576 Because these scripts may be executed with standard output
3577 redirected into a pipe for logging purposes, Perl scripts
3578 should set unbuffered output by setting <tt>$|=1</tt> so
3579 that the output is printed immediately rather than being
3583 <sect id="exitstatus">
3584 <heading>Exit status</heading>
3587 Each script must return a zero exit status for
3588 success, or a nonzero one for failure, since the package
3589 management system looks for the exit status of these scripts
3590 and determines what action to take next based on that datum.
3594 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3599 <list compact="compact">
3601 <var>new-preinst</var> <tt>install</tt>
3604 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3607 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3610 <var>old-preinst</var> <tt>abort-upgrade</tt>
3611 <var>new-version</var>
3616 <list compact="compact">
3618 <var>postinst</var> <tt>configure</tt>
3619 <var>most-recently-configured-version</var>
3622 <var>old-postinst</var> <tt>abort-upgrade</tt>
3623 <var>new-version</var>
3626 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3627 <tt>in-favour</tt> <var>package</var>
3628 <var>new-version</var>
3631 <var>postinst</var> <tt>abort-remove</tt>
3634 <var>deconfigured's-postinst</var>
3635 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3636 <var>failed-install-package</var> <var>version</var>
3637 [<tt>removing</tt> <var>conflicting-package</var>
3643 <list compact="compact">
3645 <var>prerm</var> <tt>remove</tt>
3648 <var>old-prerm</var> <tt>upgrade</tt>
3649 <var>new-version</var>
3652 <var>new-prerm</var> <tt>failed-upgrade</tt>
3653 <var>old-version</var>
3656 <var>conflictor's-prerm</var> <tt>remove</tt>
3657 <tt>in-favour</tt> <var>package</var>
3658 <var>new-version</var>
3661 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3662 <tt>in-favour</tt> <var>package-being-installed</var>
3663 <var>version</var> [<tt>removing</tt>
3664 <var>conflicting-package</var>
3670 <list compact="compact">
3672 <var>postrm</var> <tt>remove</tt>
3675 <var>postrm</var> <tt>purge</tt>
3678 <var>old-postrm</var> <tt>upgrade</tt>
3679 <var>new-version</var>
3682 <var>new-postrm</var> <tt>failed-upgrade</tt>
3683 <var>old-version</var>
3686 <var>new-postrm</var> <tt>abort-install</tt>
3689 <var>new-postrm</var> <tt>abort-install</tt>
3690 <var>old-version</var>
3693 <var>new-postrm</var> <tt>abort-upgrade</tt>
3694 <var>old-version</var>
3697 <var>disappearer's-postrm</var> <tt>disappear</tt>
3698 <var>overwriter</var>
3699 <var>overwriter-version</var>
3705 <sect id="unpackphase">
3706 <heading>Details of unpack phase of installation or upgrade</heading>
3709 The procedure on installation/upgrade/overwrite/disappear
3710 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3711 stage of <tt>dpkg --install</tt>) is as follows. In each
3712 case, if a major error occurs (unless listed below) the
3713 actions are, in general, run backwards - this means that the
3714 maintainer scripts are run with different arguments in
3715 reverse order. These are the "error unwind" calls listed
3722 If a version of the package is already installed, call
3723 <example compact="compact">
3724 <var>old-prerm</var> upgrade <var>new-version</var>
3728 If the script runs but exits with a non-zero
3729 exit status, <prgn>dpkg</prgn> will attempt:
3730 <example compact="compact">
3731 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3733 If this works, the upgrade continues. If this
3734 does not work, the error unwind:
3735 <example compact="compact">
3736 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3738 If this works, then the old-version is
3739 "Installed", if not, the old version is in a
3740 "Failed-Config" state.
3746 If a "conflicting" package is being removed at the same time,
3747 or if any package will be broken (due to <tt>Breaks</tt>):
3750 If <tt>--auto-deconfigure</tt> is
3751 specified, call, for each package to be deconfigured
3752 due to <tt>Breaks</tt>:
3753 <example compact="compact">
3754 <var>deconfigured's-prerm</var> deconfigure \
3755 in-favour <var>package-being-installed</var> <var>version</var>
3758 <example compact="compact">
3759 <var>deconfigured's-postinst</var> abort-deconfigure \
3760 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3762 The deconfigured packages are marked as
3763 requiring configuration, so that if
3764 <tt>--install</tt> is used they will be
3765 configured again if possible.
3768 If any packages depended on a conflicting
3769 package being removed and <tt>--auto-deconfigure</tt> is
3770 specified, call, for each such package:
3771 <example compact="compact">
3772 <var>deconfigured's-prerm</var> deconfigure \
3773 in-favour <var>package-being-installed</var> <var>version</var> \
3774 removing <var>conflicting-package</var> <var>version</var>
3777 <example compact="compact">
3778 <var>deconfigured's-postinst</var> abort-deconfigure \
3779 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3780 removing <var>conflicting-package</var> <var>version</var>
3782 The deconfigured packages are marked as
3783 requiring configuration, so that if
3784 <tt>--install</tt> is used they will be
3785 configured again if possible.
3788 To prepare for removal of each conflicting package, call:
3789 <example compact="compact">
3790 <var>conflictor's-prerm</var> remove \
3791 in-favour <var>package</var> <var>new-version</var>
3794 <example compact="compact">
3795 <var>conflictor's-postinst</var> abort-remove \
3796 in-favour <var>package</var> <var>new-version</var>
3805 If the package is being upgraded, call:
3806 <example compact="compact">
3807 <var>new-preinst</var> upgrade <var>old-version</var>
3809 If this fails, we call:
3811 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3818 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3820 is called. If this works, then the old version
3821 is in an "Installed" state, or else it is left
3822 in an "Unpacked" state.
3827 If it fails, then the old version is left
3828 in an "Half-Installed" state.
3835 Otherwise, if the package had some configuration
3836 files from a previous version installed (i.e., it
3837 is in the "configuration files only" state):
3838 <example compact="compact">
3839 <var>new-preinst</var> install <var>old-version</var>
3843 <var>new-postrm</var> abort-install <var>old-version</var>
3845 If this fails, the package is left in a
3846 "Half-Installed" state, which requires a
3847 reinstall. If it works, the packages is left in
3848 a "Config Files" state.
3851 Otherwise (i.e., the package was completely purged):
3852 <example compact="compact">
3853 <var>new-preinst</var> install
3856 <example compact="compact">
3857 <var>new-postrm</var> abort-install
3859 If the error-unwind fails, the package is in a
3860 "Half Installed" phase, and requires a
3861 reinstall. If the error unwind works, the
3862 package is in a not installed state.
3869 The new package's files are unpacked, overwriting any
3870 that may be on the system already, for example any
3871 from the old version of the same package or from
3872 another package. Backups of the old files are kept
3873 temporarily, and if anything goes wrong the package
3874 management system will attempt to put them back as
3875 part of the error unwind.
3879 It is an error for a package to contain files which
3880 are on the system in another package, unless
3881 <tt>Replaces</tt> is used (see <ref id="replaces">).
3883 The following paragraph is not currently the case:
3884 Currently the <tt>- - force-overwrite</tt> flag is
3885 enabled, downgrading it to a warning, but this may not
3891 It is a more serious error for a package to contain a
3892 plain file or other kind of non-directory where another
3893 package has a directory (again, unless
3894 <tt>Replaces</tt> is used). This error can be
3895 overridden if desired using
3896 <tt>--force-overwrite-dir</tt>, but this is not
3901 Packages which overwrite each other's files produce
3902 behavior which, though deterministic, is hard for the
3903 system administrator to understand. It can easily
3904 lead to "missing" programs if, for example, a package
3905 is installed which overwrites a file from another
3906 package, and is then removed again.<footnote>
3907 Part of the problem is due to what is arguably a
3908 bug in <prgn>dpkg</prgn>.
3913 A directory will never be replaced by a symbolic link
3914 to a directory or vice versa; instead, the existing
3915 state (symlink or not) will be left alone and
3916 <prgn>dpkg</prgn> will follow the symlink if there is
3925 If the package is being upgraded, call
3926 <example compact="compact">
3927 <var>old-postrm</var> upgrade <var>new-version</var>
3931 If this fails, <prgn>dpkg</prgn> will attempt:
3932 <example compact="compact">
3933 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3935 If this works, installation continues. If not,
3937 <example compact="compact">
3938 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3940 If this fails, the old version is left in an
3941 "Half Installed" state. If it works, dpkg now
3943 <example compact="compact">
3944 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3946 If this fails, the old version is left in an
3947 "Half Installed" state. If it works, dpkg now
3949 <example compact="compact">
3950 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3952 If this fails, the old version is in an
3959 This is the point of no return - if
3960 <prgn>dpkg</prgn> gets this far, it won't back off
3961 past this point if an error occurs. This will
3962 leave the package in a fairly bad state, which
3963 will require a successful re-installation to clear
3964 up, but it's when <prgn>dpkg</prgn> starts doing
3965 things that are irreversible.
3970 Any files which were in the old version of the package
3971 but not in the new are removed.
3975 The new file list replaces the old.
3979 The new maintainer scripts replace the old.
3983 Any packages all of whose files have been overwritten
3984 during the installation, and which aren't required for
3985 dependencies, are considered to have been removed.
3986 For each such package
3989 <prgn>dpkg</prgn> calls:
3990 <example compact="compact">
3991 <var>disappearer's-postrm</var> disappear \
3992 <var>overwriter</var> <var>overwriter-version</var>
3996 The package's maintainer scripts are removed.
3999 It is noted in the status database as being in a
4000 sane state, namely not installed (any conffiles
4001 it may have are ignored, rather than being
4002 removed by <prgn>dpkg</prgn>). Note that
4003 disappearing packages do not have their prerm
4004 called, because <prgn>dpkg</prgn> doesn't know
4005 in advance that the package is going to
4012 Any files in the package we're unpacking that are also
4013 listed in the file lists of other packages are removed
4014 from those lists. (This will lobotomize the file list
4015 of the "conflicting" package if there is one.)
4019 The backup files made during installation, above, are
4025 The new package's status is now sane, and recorded as
4030 Here is another point of no return - if the
4031 conflicting package's removal fails we do not unwind
4032 the rest of the installation; the conflicting package
4033 is left in a half-removed limbo.
4038 If there was a conflicting package we go and do the
4039 removal actions (described below), starting with the
4040 removal of the conflicting package's files (any that
4041 are also in the package being installed have already
4042 been removed from the conflicting package's file list,
4043 and so do not get removed now).
4049 <sect id="configdetails"><heading>Details of configuration</heading>
4052 When we configure a package (this happens with <tt>dpkg
4053 --install</tt> and <tt>dpkg --configure</tt>), we first
4054 update any <tt>conffile</tt>s and then call:
4055 <example compact="compact">
4056 <var>postinst</var> configure <var>most-recently-configured-version</var>
4061 No attempt is made to unwind after errors during
4062 configuration. If the configuration fails, the package is in
4063 a "Failed Config" state, and an error message is generated.
4067 If there is no most recently configured version
4068 <prgn>dpkg</prgn> will pass a null argument.
4071 Historical note: Truly ancient (pre-1997) versions of
4072 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4073 (including the angle brackets) in this case. Even older
4074 ones did not pass a second argument at all, under any
4075 circumstance. Note that upgrades using such an old dpkg
4076 version are unlikely to work for other reasons, even if
4077 this old argument behavior is handled by your postinst script.
4083 <sect id="removedetails"><heading>Details of removal and/or
4084 configuration purging</heading>
4090 <example compact="compact">
4091 <var>prerm</var> remove
4095 If prerm fails during replacement due to conflict
4097 <var>conflictor's-postinst</var> abort-remove \
4098 in-favour <var>package</var> <var>new-version</var>
4102 <var>postinst</var> abort-remove
4106 If this fails, the package is in a "Failed-Config"
4107 state, or else it remains "Installed".
4111 The package's files are removed (except <tt>conffile</tt>s).
4114 <example compact="compact">
4115 <var>postrm</var> remove
4119 If it fails, there's no error unwind, and the package is in
4120 an "Half-Installed" state.
4125 All the maintainer scripts except the <prgn>postrm</prgn>
4130 If we aren't purging the package we stop here. Note
4131 that packages which have no <prgn>postrm</prgn> and no
4132 <tt>conffile</tt>s are automatically purged when
4133 removed, as there is no difference except for the
4134 <prgn>dpkg</prgn> status.
4138 The <tt>conffile</tt>s and any backup files
4139 (<tt>~</tt>-files, <tt>#*#</tt> files,
4140 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4145 <example compact="compact">
4146 <var>postrm</var> purge
4150 If this fails, the package remains in a "Config-Files"
4155 The package's file list is removed.
4164 <chapt id="relationships">
4165 <heading>Declaring relationships between packages</heading>
4167 <sect id="depsyntax">
4168 <heading>Syntax of relationship fields</heading>
4171 These fields all have a uniform syntax. They are a list of
4172 package names separated by commas.
4176 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4177 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4178 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4179 control file fields of the package, which declare
4180 dependencies on other packages, the package names listed may
4181 also include lists of alternative package names, separated
4182 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4183 if any one of the alternative packages is installed, that
4184 part of the dependency is considered to be satisfied.
4188 All of the fields except for <tt>Provides</tt> may restrict
4189 their applicability to particular versions of each named
4190 package. This is done in parentheses after each individual
4191 package name; the parentheses should contain a relation from
4192 the list below followed by a version number, in the format
4193 described in <ref id="f-Version">.
4197 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4198 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4199 strictly earlier, earlier or equal, exactly equal, later or
4200 equal and strictly later, respectively. The deprecated
4201 forms <tt><</tt> and <tt>></tt> were used to mean
4202 earlier/later or equal, rather than strictly earlier/later,
4203 so they should not appear in new packages (though
4204 <prgn>dpkg</prgn> still supports them).
4208 Whitespace may appear at any point in the version
4209 specification subject to the rules in <ref
4210 id="controlsyntax">, and must appear where it's necessary to
4211 disambiguate; it is not otherwise significant. All of the
4212 relationship fields may span multiple lines. For
4213 consistency and in case of future changes to
4214 <prgn>dpkg</prgn> it is recommended that a single space be
4215 used after a version relationship and before a version
4216 number; it is also conventional to put a single space after
4217 each comma, on either side of each vertical bar, and before
4218 each open parenthesis. When wrapping a relationship field, it
4219 is conventional to do so after a comma and before the space
4220 following that comma.
4224 For example, a list of dependencies might appear as:
4225 <example compact="compact">
4228 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4233 All fields that specify build-time relationships
4234 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4235 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4236 may be restricted to a certain set of architectures. This
4237 is indicated in brackets after each individual package name and
4238 the optional version specification. The brackets enclose a
4239 list of Debian architecture names separated by whitespace.
4240 Exclamation marks may be prepended to each of the names.
4241 (It is not permitted for some names to be prepended with
4242 exclamation marks while others aren't.) If the current Debian
4243 host architecture is not in this list and there are no
4244 exclamation marks in the list, or it is in the list with a
4245 prepended exclamation mark, the package name and the
4246 associated version specification are ignored completely for
4247 the purposes of defining the relationships.
4252 <example compact="compact">
4254 Build-Depends-Indep: texinfo
4255 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4256 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4258 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4259 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4260 <tt>gnumach-dev</tt> only on hurd-i386.
4264 If the architecture-restricted dependency is part of a set of
4265 alternatives using <tt>|</tt>, that alternative is ignored
4266 completely on architectures that do not match the restriction.
4268 <example compact="compact">
4269 Build-Depends: foo [!i386] | bar [!amd64]
4271 is equivalent to <tt>bar</tt> on the i386 architecture, to
4272 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4273 bar</tt> on all other architectures.
4277 Note that the binary package relationship fields such as
4278 <tt>Depends</tt> appear in one of the binary package
4279 sections of the control file, whereas the build-time
4280 relationships such as <tt>Build-Depends</tt> appear in the
4281 source package section of the control file (which is the
4285 All fields that specify build-time relationships
4286 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4287 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>) may also
4288 be restricted to a certain set of architectures using architecture
4289 wildcards. The syntax for declaring such restrictions is the same as
4290 declaring restrictions using a certain set of architectures without
4291 architecture wildcards.
4293 <example compact="compact">
4294 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4296 is equivalent to <tt>foo</tt> on architectures using the
4297 Linux kernel and any cpu, <tt>bar</tt> on architectures
4298 using any kernel and an i386 cpu, and <tt>baz</tt> on
4299 on any architecture using a kernel other than Linux.
4303 <sect id="binarydeps">
4304 <heading>Binary Dependencies - <tt>Depends</tt>,
4305 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4306 <tt>Pre-Depends</tt>
4310 Packages can declare in their control file that they have
4311 certain relationships to other packages - for example, that
4312 they may not be installed at the same time as certain other
4313 packages, and/or that they depend on the presence of others.
4317 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4318 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4319 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4320 <tt>Breaks</tt> is described in <ref id="breaks">, and
4321 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4322 rest are described below.
4326 These seven fields are used to declare a dependency
4327 relationship by one package on another. Except for
4328 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4329 depending (binary) package's control file.
4330 (<tt>Enhances</tt> appears in the recommending package's
4331 control file, and <tt>Breaks</tt> appears in the version of
4332 depended-on package which causes the named package to
4337 A <tt>Depends</tt> field takes effect <em>only</em> when a
4338 package is to be configured. It does not prevent a package
4339 being on the system in an unconfigured state while its
4340 dependencies are unsatisfied, and it is possible to replace
4341 a package whose dependencies are satisfied and which is
4342 properly installed with a different version whose
4343 dependencies are not and cannot be satisfied; when this is
4344 done the depending package will be left unconfigured (since
4345 attempts to configure it will give errors) and will not
4346 function properly. If it is necessary, a
4347 <tt>Pre-Depends</tt> field can be used, which has a partial
4348 effect even when a package is being unpacked, as explained
4349 in detail below. (The other three dependency fields,
4350 <tt>Recommends</tt>, <tt>Suggests</tt> and
4351 <tt>Enhances</tt>, are only used by the various front-ends
4352 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4353 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4357 For this reason packages in an installation run are usually
4358 all unpacked first and all configured later; this gives
4359 later versions of packages with dependencies on later
4360 versions of other packages the opportunity to have their
4361 dependencies satisfied.
4365 In case of circular dependencies, since installation or
4366 removal order honoring the dependency order can't be
4367 established, dependency loops are broken at some point
4368 (based on rules below), and some packages may not be able to
4369 rely on their dependencies being present when being
4370 installed or removed, depending on which side of the break
4371 of the circular dependency loop they happen to be on. If one
4372 of the packages in the loop has no postinst script, then the
4373 cycle will be broken at that package, so as to ensure that
4374 all postinst scripts run with the dependencies properly
4375 configured if this is possible. Otherwise the breaking point
4380 The <tt>Depends</tt> field thus allows package maintainers
4381 to impose an order in which packages should be configured.
4385 The meaning of the five dependency fields is as follows:
4387 <tag><tt>Depends</tt></tag>
4390 This declares an absolute dependency. A package will
4391 not be configured unless all of the packages listed in
4392 its <tt>Depends</tt> field have been correctly
4397 The <tt>Depends</tt> field should be used if the
4398 depended-on package is required for the depending
4399 package to provide a significant amount of
4404 The <tt>Depends</tt> field should also be used if the
4405 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4406 <prgn>postrm</prgn> scripts require the package to be
4407 present in order to run. Note, however, that the
4408 <prgn>postrm</prgn> cannot rely on any non-essential
4409 packages to be present during the <tt>purge</tt>
4413 <tag><tt>Recommends</tt></tag>
4416 This declares a strong, but not absolute, dependency.
4420 The <tt>Recommends</tt> field should list packages
4421 that would be found together with this one in all but
4422 unusual installations.
4426 <tag><tt>Suggests</tt></tag>
4428 This is used to declare that one package may be more
4429 useful with one or more others. Using this field
4430 tells the packaging system and the user that the
4431 listed packages are related to this one and can
4432 perhaps enhance its usefulness, but that installing
4433 this one without them is perfectly reasonable.
4436 <tag><tt>Enhances</tt></tag>
4438 This field is similar to Suggests but works in the
4439 opposite direction. It is used to declare that a
4440 package can enhance the functionality of another
4444 <tag><tt>Pre-Depends</tt></tag>
4447 This field is like <tt>Depends</tt>, except that it
4448 also forces <prgn>dpkg</prgn> to complete installation
4449 of the packages named before even starting the
4450 installation of the package which declares the
4451 pre-dependency, as follows:
4455 When a package declaring a pre-dependency is about to
4456 be <em>unpacked</em> the pre-dependency can be
4457 satisfied if the depended-on package is either fully
4458 configured, <em>or even if</em> the depended-on
4459 package(s) are only unpacked or half-configured,
4460 provided that they have been configured correctly at
4461 some point in the past (and not removed or partially
4462 removed since). In this case, both the
4463 previously-configured and currently unpacked or
4464 half-configured versions must satisfy any version
4465 clause in the <tt>Pre-Depends</tt> field.
4469 When the package declaring a pre-dependency is about
4470 to be <em>configured</em>, the pre-dependency will be
4471 treated as a normal <tt>Depends</tt>, that is, it will
4472 be considered satisfied only if the depended-on
4473 package has been correctly configured.
4477 <tt>Pre-Depends</tt> should be used sparingly,
4478 preferably only by packages whose premature upgrade or
4479 installation would hamper the ability of the system to
4480 continue with any upgrade that might be in progress.
4484 <tt>Pre-Depends</tt> are also required if the
4485 <prgn>preinst</prgn> script depends on the named
4486 package. It is best to avoid this situation if
4494 When selecting which level of dependency to use you should
4495 consider how important the depended-on package is to the
4496 functionality of the one declaring the dependency. Some
4497 packages are composed of components of varying degrees of
4498 importance. Such a package should list using
4499 <tt>Depends</tt> the package(s) which are required by the
4500 more important components. The other components'
4501 requirements may be mentioned as Suggestions or
4502 Recommendations, as appropriate to the components' relative
4508 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4511 When one binary package declares that it breaks another,
4512 <prgn>dpkg</prgn> will refuse to allow the package which
4513 declares <tt>Breaks</tt> be installed unless the broken
4514 package is deconfigured first, and it will refuse to
4515 allow the broken package to be reconfigured.
4519 A package will not be regarded as causing breakage merely
4520 because its configuration files are still installed; it must
4521 be at least half-installed.
4525 A special exception is made for packages which declare that
4526 they break their own package name or a virtual package which
4527 they provide (see below): this does not count as a real
4532 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4533 version clause; such a <tt>Breaks</tt> is introduced in the
4534 version of an (implicit or explicit) dependency which
4535 violates an assumption or reveals a bug in earlier versions
4536 of the broken package. This use of <tt>Breaks</tt> will
4537 inform higher-level package management tools that broken
4538 package must be upgraded before the new one.
4542 If the breaking package also overwrites some files from the
4543 older package, it should use <tt>Replaces</tt> (not
4544 <tt>Conflicts</tt>) to ensure this goes smoothly.
4548 <sect id="conflicts">
4549 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4552 When one binary package declares a conflict with another
4553 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4554 refuse to allow them to be installed on the system at the
4559 If one package is to be installed, the other must be removed
4560 first - if the package being installed is marked as
4561 replacing (see <ref id="replaces">) the one on the system,
4562 or the one on the system is marked as deselected, or both
4563 packages are marked <tt>Essential</tt>, then
4564 <prgn>dpkg</prgn> will automatically remove the package
4565 which is causing the conflict, otherwise it will halt the
4566 installation of the new package with an error. This
4567 mechanism is specifically designed to produce an error when
4568 the installed package is <tt>Essential</tt>, but the new
4573 A package will not cause a conflict merely because its
4574 configuration files are still installed; it must be at least
4579 A special exception is made for packages which declare a
4580 conflict with their own package name, or with a virtual
4581 package which they provide (see below): this does not
4582 prevent their installation, and allows a package to conflict
4583 with others providing a replacement for it. You use this
4584 feature when you want the package in question to be the only
4585 package providing some feature.
4589 A <tt>Conflicts</tt> entry should almost never have an
4590 "earlier than" version clause. This would prevent
4591 <prgn>dpkg</prgn> from upgrading or installing the package
4592 which declared such a conflict until the upgrade or removal
4593 of the conflicted-with package had been completed. Instead,
4594 <tt>Breaks</tt> may be used.
4598 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4602 As well as the names of actual ("concrete") packages, the
4603 package relationship fields <tt>Depends</tt>,
4604 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4605 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4606 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4607 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4608 may mention "virtual packages".
4612 A <em>virtual package</em> is one which appears in the
4613 <tt>Provides</tt> control file field of another package.
4614 The effect is as if the package(s) which provide a
4615 particular virtual package name had been listed by name
4616 everywhere the virtual package name appears. (See also <ref
4621 If there are both concrete and virtual packages of the same
4622 name, then the dependency may be satisfied (or the conflict
4623 caused) by either the concrete package with the name in
4624 question or any other concrete package which provides the
4625 virtual package with the name in question. This is so that,
4626 for example, supposing we have
4627 <example compact="compact">
4630 </example> and someone else releases an enhanced version of
4631 the <tt>bar</tt> package they can say:
4632 <example compact="compact">
4636 and the <tt>bar-plus</tt> package will now also satisfy the
4637 dependency for the <tt>foo</tt> package.
4641 If a relationship field has a version number attached
4642 then only real packages will be considered to see whether
4643 the relationship is satisfied (or the prohibition violated,
4644 for a conflict or breakage) - it is assumed that a real
4645 package which provides the virtual package is not of the
4646 "right" version. So, a <tt>Provides</tt> field may not
4647 contain version numbers, and the version number of the
4648 concrete package which provides a particular virtual package
4649 will not be looked at when considering a dependency on or
4650 conflict with the virtual package name.
4654 It is likely that the ability will be added in a future
4655 release of <prgn>dpkg</prgn> to specify a version number for
4656 each virtual package it provides. This feature is not yet
4657 present, however, and is expected to be used only
4662 If you want to specify which of a set of real packages
4663 should be the default to satisfy a particular dependency on
4664 a virtual package, you should list the real package as an
4665 alternative before the virtual one.
4670 <sect id="replaces"><heading>Overwriting files and replacing
4671 packages - <tt>Replaces</tt></heading>
4674 Packages can declare in their control file that they should
4675 overwrite files in certain other packages, or completely
4676 replace other packages. The <tt>Replaces</tt> control file
4677 field has these two distinct purposes.
4680 <sect1><heading>Overwriting files in other packages</heading>
4683 Firstly, as mentioned before, it is usually an error for a
4684 package to contain files which are on the system in
4689 However, if the overwriting package declares that it
4690 <tt>Replaces</tt> the one containing the file being
4691 overwritten, then <prgn>dpkg</prgn> will replace the file
4692 from the old package with that from the new. The file
4693 will no longer be listed as "owned" by the old package.
4697 If a package is completely replaced in this way, so that
4698 <prgn>dpkg</prgn> does not know of any files it still
4699 contains, it is considered to have "disappeared". It will
4700 be marked as not wanted on the system (selected for
4701 removal) and not installed. Any <tt>conffile</tt>s
4702 details noted for the package will be ignored, as they
4703 will have been taken over by the overwriting package. The
4704 package's <prgn>postrm</prgn> script will be run with a
4705 special argument to allow the package to do any final
4706 cleanup required. See <ref id="mscriptsinstact">.
4709 Replaces is a one way relationship -- you have to
4710 install the replacing package after the replaced
4717 For this usage of <tt>Replaces</tt>, virtual packages (see
4718 <ref id="virtual">) are not considered when looking at a
4719 <tt>Replaces</tt> field - the packages declared as being
4720 replaced must be mentioned by their real names.
4724 Furthermore, this usage of <tt>Replaces</tt> only takes
4725 effect when both packages are at least partially on the
4726 system at once, so that it can only happen if they do not
4727 conflict or if the conflict has been overridden.
4732 <sect1><heading>Replacing whole packages, forcing their
4736 Secondly, <tt>Replaces</tt> allows the packaging system to
4737 resolve which package should be removed when there is a
4738 conflict - see <ref id="conflicts">. This usage only
4739 takes effect when the two packages <em>do</em> conflict,
4740 so that the two usages of this field do not interfere with
4745 In this situation, the package declared as being replaced
4746 can be a virtual package, so for example, all mail
4747 transport agents (MTAs) would have the following fields in
4748 their control files:
4749 <example compact="compact">
4750 Provides: mail-transport-agent
4751 Conflicts: mail-transport-agent
4752 Replaces: mail-transport-agent
4754 ensuring that only one MTA can be installed at any one
4759 <sect id="sourcebinarydeps">
4760 <heading>Relationships between source and binary packages -
4761 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4762 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4766 Source packages that require certain binary packages to be
4767 installed or absent at the time of building the package
4768 can declare relationships to those binary packages.
4772 This is done using the <tt>Build-Depends</tt>,
4773 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4774 <tt>Build-Conflicts-Indep</tt> control file fields.
4778 Build-dependencies on "build-essential" binary packages can be
4779 omitted. Please see <ref id="pkg-relations"> for more information.
4783 The dependencies and conflicts they define must be satisfied
4784 (as defined earlier for binary packages) in order to invoke
4785 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4787 If you make "build-arch" or "binary-arch", you need
4788 Build-Depends. If you make "build-indep" or
4789 "binary-indep", you need Build-Depends and
4790 Build-Depends-Indep. If you make "build" or "binary",
4794 There is no Build-Depends-Arch; this role is essentially
4795 met with Build-Depends. Anyone building the
4796 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4797 is basically assumed to be building the whole package
4798 anyway and so installs all build dependencies. The
4799 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4800 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4801 does not yet know how to check for its existence) and
4802 <tt>binary-arch</tt>.
4805 The purpose of the original split, I recall, was so that
4806 the autobuilders wouldn't need to install extra packages
4807 needed only for the binary-indep targets. But without a
4808 build-arch/build-indep split, this didn't work, since
4809 most of the work is done in the build target, not in the
4815 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4817 The <tt>Build-Depends</tt> and
4818 <tt>Build-Conflicts</tt> fields must be satisfied when
4819 any of the following targets is invoked:
4820 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4821 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4822 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4824 <tag><tt>Build-Depends-Indep</tt>,
4825 <tt>Build-Conflicts-Indep</tt></tag>
4827 The <tt>Build-Depends-Indep</tt> and
4828 <tt>Build-Conflicts-Indep</tt> fields must be
4829 satisfied when any of the following targets is
4830 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4831 <tt>binary</tt> and <tt>binary-indep</tt>.
4841 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4844 Packages containing shared libraries must be constructed with
4845 a little care to make sure that the shared library is always
4846 available. This is especially important for packages whose
4847 shared libraries are vitally important, such as the C library
4848 (currently <tt>libc6</tt>).
4852 Packages involving shared libraries should be split up into
4853 several binary packages. This section mostly deals with how
4854 this separation is to be accomplished; rules for files within
4855 the shared library packages are in <ref id="libraries"> instead.
4858 <sect id="sharedlibs-runtime">
4859 <heading>Run-time shared libraries</heading>
4862 The run-time shared library needs to be placed in a package
4863 whose name changes whenever the shared object version
4866 Since it is common place to install several versions of a
4867 package that just provides shared libraries, it is a
4868 good idea that the library package should not
4869 contain any extraneous non-versioned files, unless they
4870 happen to be in versioned directories.</p>
4872 The most common mechanism is to place it in a package
4874 <package><var>libraryname</var><var>soversion</var></package>,
4875 where <file><var>soversion</var></file> is the version number
4876 in the soname of the shared library<footnote>
4877 The soname is the shared object name: it's the thing
4878 that has to match exactly between building an executable
4879 and running it for the dynamic linker to be able run the
4880 program. For example, if the soname of the library is
4881 <file>libfoo.so.6</file>, the library package would be
4882 called <file>libfoo6</file>.
4884 Alternatively, if it would be confusing to directly append
4885 <var>soversion</var> to <var>libraryname</var> (e.g. because
4886 <var>libraryname</var> itself ends in a number), you may use
4887 <package><var>libraryname</var>-<var>soversion</var></package> and
4888 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4893 If you have several shared libraries built from the same
4894 source tree you may lump them all together into a single
4895 shared library package, provided that you change all of
4896 their sonames at once (so that you don't get filename
4897 clashes if you try to install different versions of the
4898 combined shared libraries package).
4902 The package should install the shared libraries under
4903 their normal names. For example, the <package>libgdbm3</package>
4904 package should install <file>libgdbm.so.3.0.0</file> as
4905 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4906 renamed or re-linked by any <prgn>prerm</prgn> or
4907 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4908 of renaming things safely without affecting running programs,
4909 and attempts to interfere with this are likely to lead to
4914 Shared libraries should not be installed executable, since
4915 the dynamic linker does not require this and trying to
4916 execute a shared library usually results in a core dump.
4920 The run-time library package should include the symbolic link that
4921 <prgn>ldconfig</prgn> would create for the shared libraries.
4922 For example, the <package>libgdbm3</package> package should include
4923 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4924 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4925 linker (for example <prgn>ld.so</prgn> or
4926 <prgn>ld-linux.so.*</prgn>) can find the library between the
4927 time that <prgn>dpkg</prgn> installs it and the time that
4928 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4930 The package management system requires the library to be
4931 placed before the symbolic link pointing to it in the
4932 <file>.deb</file> file. This is so that when
4933 <prgn>dpkg</prgn> comes to install the symlink
4934 (overwriting the previous symlink pointing at an older
4935 version of the library), the new shared library is already
4936 in place. In the past, this was achieved by creating the
4937 library in the temporary packaging directory before
4938 creating the symlink. Unfortunately, this was not always
4939 effective, since the building of the tar file in the
4940 <file>.deb</file> depended on the behavior of the underlying
4941 file system. Some file systems (such as reiserfs) reorder
4942 the files so that the order of creation is forgotten.
4943 Since version 1.7.0, <prgn>dpkg</prgn>
4944 reorders the files itself as necessary when building a
4945 package. Thus it is no longer important to concern
4946 oneself with the order of file creation.
4950 <sect1 id="ldconfig">
4951 <heading><tt>ldconfig</tt></heading>
4954 Any package installing shared libraries in one of the default
4955 library directories of the dynamic linker (which are currently
4956 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4957 listed in <file>/etc/ld.so.conf</file><footnote>
4959 <list compact="compact">
4960 <item>/usr/local/lib</item>
4961 <item>/usr/lib/libc5-compat</item>
4962 <item>/lib/libc5-compat</item>
4965 must use <prgn>ldconfig</prgn> to update the shared library
4970 The package maintainer scripts must only call
4971 <prgn>ldconfig</prgn> under these circumstances:
4972 <list compact="compact">
4973 <item>When the <prgn>postinst</prgn> script is run with a
4974 first argument of <tt>configure</tt>, the script must call
4975 <prgn>ldconfig</prgn>, and may optionally invoke
4976 <prgn>ldconfig</prgn> at other times.
4978 <item>When the <prgn>postrm</prgn> script is run with a
4979 first argument of <tt>remove</tt>, the script should call
4980 <prgn>ldconfig</prgn>.
4985 During install or upgrade, the preinst is called before
4986 the new files are installed, so calling "ldconfig" is
4987 pointless. The preinst of an existing package can also be
4988 called if an upgrade fails. However, this happens during
4989 the critical time when a shared libs may exist on-disk
4990 under a temporary name. Thus, it is dangerous and
4991 forbidden by current policy to call "ldconfig" at this
4996 When a package is installed or upgraded, "postinst
4997 configure" runs after the new files are safely on-disk.
4998 Since it is perfectly safe to invoke ldconfig
4999 unconditionally in a postinst, it is OK for a package to
5000 simply put ldconfig in its postinst without checking the
5001 argument. The postinst can also be called to recover from
5002 a failed upgrade. This happens before any new files are
5003 unpacked, so there is no reason to call "ldconfig" at this
5008 For a package that is being removed, prerm is
5009 called with all the files intact, so calling ldconfig is
5010 useless. The other calls to "prerm" happen in the case of
5011 upgrade at a time when all the files of the old package
5012 are on-disk, so again calling "ldconfig" is pointless.
5016 postrm, on the other hand, is called with the "remove"
5017 argument just after the files are removed, so this is
5018 the proper time to call "ldconfig" to notify the system
5019 of the fact that the shared libraries from the package
5020 are removed. The postrm can be called at several other
5021 times. At the time of "postrm purge", "postrm
5022 abort-install", or "postrm abort-upgrade", calling
5023 "ldconfig" is useless because the shared lib files are
5024 not on-disk. However, when "postrm" is invoked with
5025 arguments "upgrade", "failed-upgrade", or "disappear", a
5026 shared lib may exist on-disk under a temporary filename.
5034 <sect id="sharedlibs-support-files">
5035 <heading>Shared library support files</heading>
5038 If your package contains files whose names do not change with
5039 each change in the library shared object version, you must not
5040 put them in the shared library package. Otherwise, several
5041 versions of the shared library cannot be installed at the same
5042 time without filename clashes, making upgrades and transitions
5043 unnecessarily difficult.
5047 It is recommended that supporting files and run-time support
5048 programs that do not need to be invoked manually by users, but
5049 are nevertheless required for the package to function, be placed
5050 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5051 preferably under <file>/usr/lib/</file><var>package-name</var>.
5052 If the program or file is architecture independent, the
5053 recommendation is for it to be placed in a subdirectory of
5054 <file>/usr/share</file> instead, preferably under
5055 <file>/usr/share/</file><var>package-name</var>. Following the
5056 <var>package-name</var> naming convention ensures that the file
5057 names change when the shared object version changes.
5061 Run-time support programs that use the shared library but are
5062 not required for the library to function or files used by the
5063 shared library that can be used by any version of the shared
5064 library package should instead be put in a separate package.
5065 This package might typically be named
5066 <package><var>libraryname</var>-tools</package>; note the
5067 absence of the <var>soversion</var> in the package name.
5071 Files and support programs only useful when compiling software
5072 against the library should be included in the development
5073 package for the library.<footnote>
5074 For example, a <file><var>package-name</var>-config</file>
5075 script or <package>pkg-config</package> configuration files.
5080 <sect id="sharedlibs-static">
5081 <heading>Static libraries</heading>
5084 The static library (<file><var>libraryname.a</var></file>)
5085 is usually provided in addition to the shared version.
5086 It is placed into the development package (see below).
5090 In some cases, it is acceptable for a library to be
5091 available in static form only; these cases include:
5093 <item>libraries for languages whose shared library support
5094 is immature or unstable</item>
5095 <item>libraries whose interfaces are in flux or under
5096 development (commonly the case when the library's
5097 major version number is zero, or where the ABI breaks
5098 across patchlevels)</item>
5099 <item>libraries which are explicitly intended to be
5100 available only in static form by their upstream
5105 <sect id="sharedlibs-dev">
5106 <heading>Development files</heading>
5109 The development files associated to a shared library need to be
5110 placed in a package called
5111 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5112 or if you prefer only to support one development version at a
5113 time, <package><var>libraryname</var>-dev</package>.
5117 In case several development versions of a library exist, you may
5118 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5119 <ref id="conflicts">) to ensure that the user only installs one
5120 development version at a time (as different development versions are
5121 likely to have the same header files in them, which would cause a
5122 filename clash if both were installed).
5126 The development package should contain a symlink for the associated
5127 shared library without a version number. For example, the
5128 <package>libgdbm-dev</package> package should include a symlink
5129 from <file>/usr/lib/libgdbm.so</file> to
5130 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5131 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5132 <file>libgdbm.so</file> when compiling dynamically.
5136 <sect id="sharedlibs-intradeps">
5137 <heading>Dependencies between the packages of the same library</heading>
5140 Typically the development version should have an exact
5141 version dependency on the runtime library, to make sure that
5142 compilation and linking happens correctly. The
5143 <tt>${binary:Version}</tt> substitution variable can be
5144 useful for this purpose.
5146 Previously, <tt>${Source-Version}</tt> was used, but its name
5147 was confusing and it has been deprecated since dpkg 1.13.19.
5152 <sect id="sharedlibs-shlibdeps">
5153 <heading>Dependencies between the library and other packages -
5154 the <tt>shlibs</tt> system</heading>
5157 If a package contains a binary or library which links to a
5158 shared library, we must ensure that when the package is
5159 installed on the system, all of the libraries needed are
5160 also installed. This requirement led to the creation of the
5161 <tt>shlibs</tt> system, which is very simple in its design:
5162 any package which <em>provides</em> a shared library also
5163 provides information on the package dependencies required to
5164 ensure the presence of this library, and any package which
5165 <em>uses</em> a shared library uses this information to
5166 determine the dependencies it requires. The files which
5167 contain the mapping from shared libraries to the necessary
5168 dependency information are called <file>shlibs</file> files.
5172 Thus, when a package is built which contains any shared
5173 libraries, it must provide a <file>shlibs</file> file for other
5174 packages to use, and when a package is built which contains
5175 any shared libraries or compiled binaries, it must run
5176 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5177 on these to determine the libraries used and hence the
5178 dependencies needed by this package.<footnote>
5180 In the past, the shared libraries linked to were
5181 determined by calling <prgn>ldd</prgn>, but now
5182 <prgn>objdump</prgn> is used to do this. The only
5183 change this makes to package building is that
5184 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5185 libraries, whereas in the past this was unnecessary.
5186 The rest of this footnote explains the advantage that
5191 We say that a binary <tt>foo</tt> <em>directly</em> uses
5192 a library <tt>libbar</tt> if it is explicitly linked
5193 with that library (that is, it uses the flag
5194 <tt>-lbar</tt> during the linking stage). Other
5195 libraries that are needed by <tt>libbar</tt> are linked
5196 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5197 linker will load them automatically when it loads
5198 <tt>libbar</tt>. A package should depend on
5199 the libraries it directly uses, and the dependencies for
5200 those libraries should automatically pull in the other
5205 Unfortunately, the <prgn>ldd</prgn> program shows both
5206 the directly and indirectly used libraries, meaning that
5207 the dependencies determined included both direct and
5208 indirect dependencies. The use of <prgn>objdump</prgn>
5209 avoids this problem by determining only the directly
5214 A good example of where this helps is the following. We
5215 could update <tt>libimlib</tt> with a new version that
5216 supports a new graphics format called dgf (but retaining
5217 the same major version number). If we used the old
5218 <prgn>ldd</prgn> method, every package that uses
5219 <tt>libimlib</tt> would need to be recompiled so it
5220 would also depend on <tt>libdgf</tt> or it wouldn't run
5221 due to missing symbols. However with the new system,
5222 packages using <tt>libimlib</tt> can rely on
5223 <tt>libimlib</tt> itself having the dependency on
5224 <tt>libdgf</tt> and so they would not need rebuilding.
5230 In the following sections, we will first describe where the
5231 various <tt>shlibs</tt> files are to be found, then how to
5232 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5233 file format and how to create them if your package contains a
5238 <heading>The <tt>shlibs</tt> files present on the system</heading>
5241 There are several places where <tt>shlibs</tt> files are
5242 found. The following list gives them in the order in which
5244 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5245 (The first one which gives the required information is used.)
5251 <p><file>debian/shlibs.local</file></p>
5254 This lists overrides for this package. Its use is
5255 described below (see <ref id="shlibslocal">).
5260 <p><file>/etc/dpkg/shlibs.override</file></p>
5263 This lists global overrides. This list is normally
5264 empty. It is maintained by the local system
5270 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5273 When packages are being built, any
5274 <file>debian/shlibs</file> files are copied into the
5275 control file area of the temporary build directory and
5276 given the name <file>shlibs</file>. These files give
5277 details of any shared libraries included in the
5279 An example may help here. Let us say that the
5280 source package <tt>foo</tt> generates two binary
5281 packages, <tt>libfoo2</tt> and
5282 <tt>foo-runtime</tt>. When building the binary
5283 packages, the two packages are created in the
5284 directories <file>debian/libfoo2</file> and
5285 <file>debian/foo-runtime</file> respectively.
5286 (<file>debian/tmp</file> could be used instead of one
5287 of these.) Since <tt>libfoo2</tt> provides the
5288 <tt>libfoo</tt> shared library, it will require a
5289 <tt>shlibs</tt> file, which will be installed in
5290 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5292 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5293 when <prgn>dpkg-shlibdeps</prgn> is run on the
5295 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5297 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5298 determine whether <tt>foo-prog</tt>'s library
5299 dependencies are satisfied by any of the libraries
5300 provided by <tt>libfoo2</tt>. For this reason,
5301 <prgn>dpkg-shlibdeps</prgn> must only be run once
5302 all of the individual binary packages'
5303 <tt>shlibs</tt> files have been installed into the
5310 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5313 These are the <file>shlibs</file> files corresponding to
5314 all of the packages installed on the system, and are
5315 maintained by the relevant package maintainers.
5320 <p><file>/etc/dpkg/shlibs.default</file></p>
5323 This file lists any shared libraries whose packages
5324 have failed to provide correct <file>shlibs</file> files.
5325 It was used when the <file>shlibs</file> setup was first
5326 introduced, but it is now normally empty. It is
5327 maintained by the <tt>dpkg</tt> maintainer.
5335 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5336 <file>shlibs</file> files</heading>
5340 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5341 into your <file>debian/rules</file> file. If your package
5342 contains only compiled binaries and libraries (but no scripts),
5343 you can use a command such as:
5344 <example compact="compact">
5345 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5346 debian/tmp/usr/lib/*
5348 Otherwise, you will need to explicitly list the compiled
5349 binaries and libraries.<footnote>
5350 If you are using <tt>debhelper</tt>, the
5351 <prgn>dh_shlibdeps</prgn> program will do this work for
5352 you. It will also correctly handle multi-binary
5358 This command puts the dependency information into the
5359 <file>debian/substvars</file> file, which is then used by
5360 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5361 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5362 field in the control file for this to work.
5366 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5367 done. If it does complain you might need to create your own
5368 <file>debian/shlibs.local</file> file, as explained below (see
5369 <ref id="shlibslocal">).
5373 If you have multiple binary packages, you will need to call
5374 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5375 compiled libraries or binaries. In such a case, you will
5376 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5377 utilities to specify a different <file>substvars</file> file.
5381 If you are creating a udeb for use in the Debian Installer, you
5382 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5383 the dependency line of type <tt>udeb</tt> by adding
5384 <tt>-tudeb</tt> as option<footnote>
5385 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5386 will automatically add this option if it knows it is
5388 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5389 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5390 fall back to the regular dependency line.
5394 For more details on dpkg-shlibdeps, please see
5395 <ref id="pkg-dpkg-shlibdeps"> and
5396 <manref name="dpkg-shlibdeps" section="1">.
5401 <heading>The <file>shlibs</file> File Format</heading>
5404 Each <file>shlibs</file> file has the same format. Lines
5405 beginning with <tt>#</tt> are considered to be comments and
5406 are ignored. Each line is of the form:
5407 <example compact="compact">
5408 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5413 We will explain this by reference to the example of the
5414 <tt>zlib1g</tt> package, which (at the time of writing)
5415 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5419 <var>type</var> is an optional element that indicates the type
5420 of package for which the line is valid. The only type currently
5421 in use is <tt>udeb</tt>. The colon and space after the type are
5426 <var>library-name</var> is the name of the shared library,
5427 in this case <tt>libz</tt>. (This must match the name part
5428 of the soname, see below.)
5432 <var>soname-version</var> is the version part of the soname of
5433 the library. The soname is the thing that must exactly match
5434 for the library to be recognized by the dynamic linker, and is
5436 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5437 example, <tt>libz.so.1</tt>.<footnote>
5438 This can be determined using the command
5439 <example compact="compact">
5440 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5443 The version part is the part which comes after
5444 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5448 <var>dependencies</var> has the same syntax as a dependency
5449 field in a binary package control file. It should give
5450 details of which packages are required to satisfy a binary
5451 built against the version of the library contained in the
5452 package. See <ref id="depsyntax"> for details.
5456 In our example, if the first version of the <tt>zlib1g</tt>
5457 package which contained a minor number of at least
5458 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5459 <tt>shlibs</tt> entry for this library could say:
5460 <example compact="compact">
5461 libz 1 zlib1g (>= 1:1.1.3)
5463 The version-specific dependency is to avoid warnings from
5464 the dynamic linker about using older shared libraries with
5469 As zlib1g also provides a udeb containing the shared library,
5470 there would also be a second line:
5471 <example compact="compact">
5472 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5478 <heading>Providing a <file>shlibs</file> file</heading>
5481 If your package provides a shared library, you need to create
5482 a <file>shlibs</file> file following the format described above.
5483 It is usual to call this file <file>debian/shlibs</file> (but if
5484 you have multiple binary packages, you might want to call it
5485 <file>debian/shlibs.<var>package</var></file> instead). Then
5486 let <file>debian/rules</file> install it in the control area:
5487 <example compact="compact">
5488 install -m644 debian/shlibs debian/tmp/DEBIAN
5490 or, in the case of a multi-binary package:
5491 <example compact="compact">
5492 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5494 An alternative way of doing this is to create the
5495 <file>shlibs</file> file in the control area directly from
5496 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5497 file at all,<footnote>
5498 This is what <prgn>dh_makeshlibs</prgn> in the
5499 <tt>debhelper</tt> suite does. If your package also has a udeb
5500 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5501 automatically generate the <tt>udeb:</tt> lines if you specify
5502 the name of the udeb with the <tt>--add-udeb</tt> option.
5504 since the <file>debian/shlibs</file> file itself is ignored by
5505 <prgn>dpkg-shlibdeps</prgn>.
5509 As <prgn>dpkg-shlibdeps</prgn> reads the
5510 <file>DEBIAN/shlibs</file> files in all of the binary packages
5511 being built from this source package, all of the
5512 <file>DEBIAN/shlibs</file> files should be installed before
5513 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5518 <sect1 id="shlibslocal">
5519 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5522 This file is intended only as a <em>temporary</em> fix if
5523 your binaries or libraries depend on a library whose package
5524 does not yet provide a correct <file>shlibs</file> file.
5528 We will assume that you are trying to package a binary
5529 <tt>foo</tt>. When you try running
5530 <prgn>dpkg-shlibdeps</prgn> you get the following error
5531 message (<tt>-O</tt> displays the dependency information on
5532 <tt>stdout</tt> instead of writing it to
5533 <tt>debian/substvars</tt>, and the lines have been wrapped
5534 for ease of reading):
5535 <example compact="compact">
5536 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5537 dpkg-shlibdeps: warning: unable to find dependency
5538 information for shared library libbar (soname 1,
5539 path /usr/lib/libbar.so.1, dependency field Depends)
5540 shlibs:Depends=libc6 (>= 2.2.2-2)
5542 You can then run <prgn>ldd</prgn> on the binary to find the
5543 full location of the library concerned:
5544 <example compact="compact">
5546 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5547 libc.so.6 => /lib/libc.so.6 (0x40032000)
5548 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5550 So the <prgn>foo</prgn> binary depends on the
5551 <prgn>libbar</prgn> shared library, but no package seems to
5552 provide a <file>*.shlibs</file> file handling
5553 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5554 determine the package responsible:
5555 <example compact="compact">
5556 $ dpkg -S /usr/lib/libbar.so.1
5557 bar1: /usr/lib/libbar.so.1
5558 $ dpkg -s bar1 | grep Version
5561 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5562 is the one we are using. Now we can file a bug against the
5563 <tt>bar1</tt> package and create our own
5564 <file>debian/shlibs.local</file> to locally fix the problem.
5565 Including the following line into your
5566 <file>debian/shlibs.local</file> file:
5567 <example compact="compact">
5568 libbar 1 bar1 (>= 1.0-1)
5570 should allow the package build to work.
5574 As soon as the maintainer of <tt>bar1</tt> provides a
5575 correct <file>shlibs</file> file, you should remove this line
5576 from your <file>debian/shlibs.local</file> file. (You should
5577 probably also then have a versioned <tt>Build-Depends</tt>
5578 on <tt>bar1</tt> to help ensure that others do not have the
5579 same problem building your package.)
5588 <chapt id="opersys"><heading>The Operating System</heading>
5591 <heading>File system hierarchy</heading>
5595 <heading>File System Structure</heading>
5598 The location of all installed files and directories must
5599 comply with the Filesystem Hierarchy Standard (FHS),
5600 version 2.3, with the exceptions noted below, and except
5601 where doing so would violate other terms of Debian
5602 Policy. The following exceptions to the FHS apply:
5607 The optional rules related to user specific
5608 configuration files for applications are stored in
5609 the user's home directory are relaxed. It is
5610 recommended that such files start with the
5611 '<tt>.</tt>' character (a "dot file"), and if an
5612 application needs to create more than one dot file
5613 then the preferred placement is in a subdirectory
5614 with a name starting with a '.' character, (a "dot
5615 directory"). In this case it is recommended the
5616 configuration files not start with the '.'
5622 The requirement for amd64 to use <file>/lib64</file>
5623 for 64 bit binaries is removed.
5628 The requirement for object files, internal binaries, and
5629 libraries, including <file>libc.so.*</file>, to be located
5630 directly under <file>/lib{,32}</file> and
5631 <file>/usr/lib{,32}</file> is amended, permitting files
5632 to instead be installed to
5633 <file>/lib/<var>triplet</var></file> and
5634 <file>/usr/lib/<var>triplet</var></file>, where
5635 <tt><var>triplet</var></tt> is the value returned by
5636 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5637 architecture of the package. Packages may <em>not</em>
5638 install files to any <var>triplet</var> path other
5639 than the one matching the architecture of that package;
5640 for instance, an <tt>Architecture: amd64</tt> package
5641 containing 32-bit x86 libraries may not install these
5642 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5644 This is necessary in order to reserve the directories for
5645 use in cross-installation of library packages from other
5646 architectures, as part of the planned deployment of
5651 Applications may also use a single subdirectory under
5652 <file>/usr/lib/<var>triplet</var></file>.
5655 The execution time linker/loader, ld*, must still be made
5656 available in the existing location under /lib or /lib64
5657 since this is part of the ELF ABI for the architecture.
5662 The requirement that
5663 <file>/usr/local/share/man</file> be "synonymous"
5664 with <file>/usr/local/man</file> is relaxed to a
5669 The requirement that windowmanagers with a single
5670 configuration file call it <file>system.*wmrc</file>
5671 is removed, as is the restriction that the window
5672 manager subdirectory be named identically to the
5673 window manager name itself.
5678 The requirement that boot manager configuration
5679 files live in <file>/etc</file>, or at least are
5680 symlinked there, is relaxed to a recommendation.
5687 The version of this document referred here can be
5688 found in the <tt>debian-policy</tt> package or on <url
5689 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5690 name="FHS (Debian copy)"> alongside this manual (or, if
5691 you have the <package>debian-policy</package> installed,
5693 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5694 (local copy)">). The
5695 latest version, which may be a more recent version, may
5697 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5698 Specific questions about following the standard may be
5699 asked on the <tt>debian-devel</tt> mailing list, or
5700 referred to the FHS mailing list (see the
5701 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5707 <heading>Site-specific programs</heading>
5710 As mandated by the FHS, packages must not place any
5711 files in <file>/usr/local</file>, either by putting them in
5712 the file system archive to be unpacked by <prgn>dpkg</prgn>
5713 or by manipulating them in their maintainer scripts.
5717 However, the package may create empty directories below
5718 <file>/usr/local</file> so that the system administrator knows
5719 where to place site-specific files. These are not
5720 directories <em>in</em> <file>/usr/local</file>, but are
5721 children of directories in <file>/usr/local</file>. These
5722 directories (<file>/usr/local/*/dir/</file>)
5723 should be removed on package removal if they are
5728 Note, that this applies only to directories <em>below</em>
5729 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5730 Packages must not create sub-directories in the directory
5731 <file>/usr/local</file> itself, except those listed in FHS,
5732 section 4.5. However, you may create directories below
5733 them as you wish. You must not remove any of the
5734 directories listed in 4.5, even if you created them.
5738 Since <file>/usr/local</file> can be mounted read-only from a
5739 remote server, these directories must be created and
5740 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5741 maintainer scripts and not be included in the
5742 <file>.deb</file> archive. These scripts must not fail if
5743 either of these operations fail.
5747 For example, the <tt>emacsen-common</tt> package could
5748 contain something like
5749 <example compact="compact">
5750 if [ ! -e /usr/local/share/emacs ]
5752 if mkdir /usr/local/share/emacs 2>/dev/null
5754 chown root:staff /usr/local/share/emacs
5755 chmod 2775 /usr/local/share/emacs
5759 in its <prgn>postinst</prgn> script, and
5760 <example compact="compact">
5761 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5762 rmdir /usr/local/share/emacs 2>/dev/null || true
5764 in the <prgn>prerm</prgn> script. (Note that this form is
5765 used to ensure that if the script is interrupted, the
5766 directory <file>/usr/local/share/emacs</file> will still be
5771 If you do create a directory in <file>/usr/local</file> for
5772 local additions to a package, you should ensure that
5773 settings in <file>/usr/local</file> take precedence over the
5774 equivalents in <file>/usr</file>.
5778 However, because <file>/usr/local</file> and its contents are
5779 for exclusive use of the local administrator, a package
5780 must not rely on the presence or absence of files or
5781 directories in <file>/usr/local</file> for normal operation.
5785 The <file>/usr/local</file> directory itself and all the
5786 subdirectories created by the package should (by default) have
5787 permissions 2775 (group-writable and set-group-id) and be
5788 owned by <tt>root:staff</tt>.
5793 <heading>The system-wide mail directory</heading>
5795 The system-wide mail directory is <file>/var/mail</file>. This
5796 directory is part of the base system and should not owned
5797 by any particular mail agents. The use of the old
5798 location <file>/var/spool/mail</file> is deprecated, even
5799 though the spool may still be physically located there.
5805 <heading>Users and groups</heading>
5808 <heading>Introduction</heading>
5810 The Debian system can be configured to use either plain or
5815 Some user ids (UIDs) and group ids (GIDs) are reserved
5816 globally for use by certain packages. Because some
5817 packages need to include files which are owned by these
5818 users or groups, or need the ids compiled into binaries,
5819 these ids must be used on any Debian system only for the
5820 purpose for which they are allocated. This is a serious
5821 restriction, and we should avoid getting in the way of
5822 local administration policies. In particular, many sites
5823 allocate users and/or local system groups starting at 100.
5827 Apart from this we should have dynamically allocated ids,
5828 which should by default be arranged in some sensible
5829 order, but the behavior should be configurable.
5833 Packages other than <tt>base-passwd</tt> must not modify
5834 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5835 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5840 <heading>UID and GID classes</heading>
5842 The UID and GID numbers are divided into classes as
5848 Globally allocated by the Debian project, the same
5849 on every Debian system. These ids will appear in
5850 the <file>passwd</file> and <file>group</file> files of all
5851 Debian systems, new ids in this range being added
5852 automatically as the <tt>base-passwd</tt> package is
5857 Packages which need a single statically allocated
5858 uid or gid should use one of these; their
5859 maintainers should ask the <tt>base-passwd</tt>
5867 Dynamically allocated system users and groups.
5868 Packages which need a user or group, but can have
5869 this user or group allocated dynamically and
5870 differently on each system, should use <tt>adduser
5871 --system</tt> to create the group and/or user.
5872 <prgn>adduser</prgn> will check for the existence of
5873 the user or group, and if necessary choose an unused
5874 id based on the ranges specified in
5875 <file>adduser.conf</file>.
5879 <tag>1000-29999:</tag>
5882 Dynamically allocated user accounts. By default
5883 <prgn>adduser</prgn> will choose UIDs and GIDs for
5884 user accounts in this range, though
5885 <file>adduser.conf</file> may be used to modify this
5890 <tag>30000-59999:</tag>
5895 <tag>60000-64999:</tag>
5898 Globally allocated by the Debian project, but only
5899 created on demand. The ids are allocated centrally
5900 and statically, but the actual accounts are only
5901 created on users' systems on demand.
5905 These ids are for packages which are obscure or
5906 which require many statically-allocated ids. These
5907 packages should check for and create the accounts in
5908 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5909 <prgn>adduser</prgn> if it has this facility) if
5910 necessary. Packages which are likely to require
5911 further allocations should have a "hole" left after
5912 them in the allocation, to give them room to
5917 <tag>65000-65533:</tag>
5925 User <tt>nobody</tt>. The corresponding gid refers
5926 to the group <tt>nogroup</tt>.
5933 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5934 not</em> be used, because it is the error return
5943 <sect id="sysvinit">
5944 <heading>System run levels and <file>init.d</file> scripts</heading>
5946 <sect1 id="/etc/init.d">
5947 <heading>Introduction</heading>
5950 The <file>/etc/init.d</file> directory contains the scripts
5951 executed by <prgn>init</prgn> at boot time and when the
5952 init state (or "runlevel") is changed (see <manref
5953 name="init" section="8">).
5957 There are at least two different, yet functionally
5958 equivalent, ways of handling these scripts. For the sake
5959 of simplicity, this document describes only the symbolic
5960 link method. However, it must not be assumed by maintainer
5961 scripts that this method is being used, and any automated
5962 manipulation of the various runlevel behaviors by
5963 maintainer scripts must be performed using
5964 <prgn>update-rc.d</prgn> as described below and not by
5965 manually installing or removing symlinks. For information
5966 on the implementation details of the other method,
5967 implemented in the <tt>file-rc</tt> package, please refer
5968 to the documentation of that package.
5972 These scripts are referenced by symbolic links in the
5973 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5974 runlevels, <prgn>init</prgn> looks in the directory
5975 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5976 execute, where <tt><var>n</var></tt> is the runlevel that
5977 is being changed to, or <tt>S</tt> for the boot-up
5982 The names of the links all have the form
5983 <file>S<var>mm</var><var>script</var></file> or
5984 <file>K<var>mm</var><var>script</var></file> where
5985 <var>mm</var> is a two-digit number and <var>script</var>
5986 is the name of the script (this should be the same as the
5987 name of the actual script in <file>/etc/init.d</file>).
5991 When <prgn>init</prgn> changes runlevel first the targets
5992 of the links whose names start with a <tt>K</tt> are
5993 executed, each with the single argument <tt>stop</tt>,
5994 followed by the scripts prefixed with an <tt>S</tt>, each
5995 with the single argument <tt>start</tt>. (The links are
5996 those in the <file>/etc/rc<var>n</var>.d</file> directory
5997 corresponding to the new runlevel.) The <tt>K</tt> links
5998 are responsible for killing services and the <tt>S</tt>
5999 link for starting services upon entering the runlevel.
6003 For example, if we are changing from runlevel 2 to
6004 runlevel 3, init will first execute all of the <tt>K</tt>
6005 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6006 all of the <tt>S</tt> prefixed scripts in that directory.
6007 The links starting with <tt>K</tt> will cause the
6008 referred-to file to be executed with an argument of
6009 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6014 The two-digit number <var>mm</var> is used to determine
6015 the order in which to run the scripts: low-numbered links
6016 have their scripts run first. For example, the
6017 <tt>K20</tt> scripts will be executed before the
6018 <tt>K30</tt> scripts. This is used when a certain service
6019 must be started before another. For example, the name
6020 server <prgn>bind</prgn> might need to be started before
6021 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6022 can set up its access lists. In this case, the script
6023 that starts <prgn>bind</prgn> would have a lower number
6024 than the script that starts <prgn>inn</prgn> so that it
6026 <example compact="compact">
6033 The two runlevels 0 (halt) and 6 (reboot) are slightly
6034 different. In these runlevels, the links with an
6035 <tt>S</tt> prefix are still called after those with a
6036 <tt>K</tt> prefix, but they too are called with the single
6037 argument <tt>stop</tt>.
6042 <heading>Writing the scripts</heading>
6045 Packages that include daemons for system services should
6046 place scripts in <file>/etc/init.d</file> to start or stop
6047 services at boot time or during a change of runlevel.
6048 These scripts should be named
6049 <file>/etc/init.d/<var>package</var></file>, and they should
6050 accept one argument, saying what to do:
6053 <tag><tt>start</tt></tag>
6054 <item>start the service,</item>
6056 <tag><tt>stop</tt></tag>
6057 <item>stop the service,</item>
6059 <tag><tt>restart</tt></tag>
6060 <item>stop and restart the service if it's already running,
6061 otherwise start the service</item>
6063 <tag><tt>reload</tt></tag>
6064 <item><p>cause the configuration of the service to be
6065 reloaded without actually stopping and restarting
6068 <tag><tt>force-reload</tt></tag>
6069 <item>cause the configuration to be reloaded if the
6070 service supports this, otherwise restart the
6074 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6075 <tt>force-reload</tt> options should be supported by all
6076 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6081 The <file>init.d</file> scripts must ensure that they will
6082 behave sensibly (i.e., returning success and not starting
6083 multiple copies of a service) if invoked with <tt>start</tt>
6084 when the service is already running, or with <tt>stop</tt>
6085 when it isn't, and that they don't kill unfortunately-named
6086 user processes. The best way to achieve this is usually to
6087 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6092 If a service reloads its configuration automatically (as
6093 in the case of <prgn>cron</prgn>, for example), the
6094 <tt>reload</tt> option of the <file>init.d</file> script
6095 should behave as if the configuration has been reloaded
6100 The <file>/etc/init.d</file> scripts must be treated as
6101 configuration files, either (if they are present in the
6102 package, that is, in the .deb file) by marking them as
6103 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6104 by managing them correctly in the maintainer scripts (see
6105 <ref id="config-files">). This is important since we want
6106 to give the local system administrator the chance to adapt
6107 the scripts to the local system, e.g., to disable a
6108 service without de-installing the package, or to specify
6109 some special command line options when starting a service,
6110 while making sure their changes aren't lost during the next
6115 These scripts should not fail obscurely when the
6116 configuration files remain but the package has been
6117 removed, as configuration files remain on the system after
6118 the package has been removed. Only when <prgn>dpkg</prgn>
6119 is executed with the <tt>--purge</tt> option will
6120 configuration files be removed. In particular, as the
6121 <file>/etc/init.d/<var>package</var></file> script itself is
6122 usually a <tt>conffile</tt>, it will remain on the system
6123 if the package is removed but not purged. Therefore, you
6124 should include a <tt>test</tt> statement at the top of the
6126 <example compact="compact">
6127 test -f <var>program-executed-later-in-script</var> || exit 0
6132 Often there are some variables in the <file>init.d</file>
6133 scripts whose values control the behavior of the scripts,
6134 and which a system administrator is likely to want to
6135 change. As the scripts themselves are frequently
6136 <tt>conffile</tt>s, modifying them requires that the
6137 administrator merge in their changes each time the package
6138 is upgraded and the <tt>conffile</tt> changes. To ease
6139 the burden on the system administrator, such configurable
6140 values should not be placed directly in the script.
6141 Instead, they should be placed in a file in
6142 <file>/etc/default</file>, which typically will have the same
6143 base name as the <file>init.d</file> script. This extra file
6144 should be sourced by the script when the script runs. It
6145 must contain only variable settings and comments in SUSv3
6146 <prgn>sh</prgn> format. It may either be a
6147 <tt>conffile</tt> or a configuration file maintained by
6148 the package maintainer scripts. See <ref id="config-files">
6153 To ensure that vital configurable values are always
6154 available, the <file>init.d</file> script should set default
6155 values for each of the shell variables it uses, either
6156 before sourcing the <file>/etc/default/</file> file or
6157 afterwards using something like the <tt>:
6158 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6159 script must behave sensibly and not fail if the
6160 <file>/etc/default</file> file is deleted.
6164 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6165 as temporary filesystems<footnote>
6166 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6167 options in <file>/etc/default/rcS</file>.
6168 </footnote>, so the <file>init.d</file> scripts must handle this
6169 correctly. This will typically amount to creating any required
6170 subdirectories dynamically when the <file>init.d</file> script
6171 is run, rather than including them in the package and relying on
6172 <prgn>dpkg</prgn> to create them.
6177 <heading>Interfacing with the initscript system</heading>
6180 Maintainers should use the abstraction layer provided by
6181 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6182 programs to deal with initscripts in their packages'
6183 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6184 and <prgn>postrm</prgn>.
6188 Directly managing the /etc/rc?.d links and directly
6189 invoking the <file>/etc/init.d/</file> initscripts should
6190 be done only by packages providing the initscript
6191 subsystem (such as <prgn>sysv-rc</prgn> and
6192 <prgn>file-rc</prgn>).
6196 <heading>Managing the links</heading>
6199 The program <prgn>update-rc.d</prgn> is provided for
6200 package maintainers to arrange for the proper creation and
6201 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6202 or their functional equivalent if another method is being
6203 used. This may be used by maintainers in their packages'
6204 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6208 You must not include any <file>/etc/rc<var>n</var>.d</file>
6209 symbolic links in the actual archive or manually create or
6210 remove the symbolic links in maintainer scripts; you must
6211 use the <prgn>update-rc.d</prgn> program instead. (The
6212 former will fail if an alternative method of maintaining
6213 runlevel information is being used.) You must not include
6214 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6215 in the archive either. (Only the <tt>sysvinit</tt>
6220 By default <prgn>update-rc.d</prgn> will start services in
6221 each of the multi-user state runlevels (2, 3, 4, and 5)
6222 and stop them in the halt runlevel (0), the single-user
6223 runlevel (1) and the reboot runlevel (6). The system
6224 administrator will have the opportunity to customize
6225 runlevels by simply adding, moving, or removing the
6226 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6227 symbolic links are being used, or by modifying
6228 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6233 To get the default behavior for your package, put in your
6234 <prgn>postinst</prgn> script
6235 <example compact="compact">
6236 update-rc.d <var>package</var> defaults
6238 and in your <prgn>postrm</prgn>
6239 <example compact="compact">
6240 if [ "$1" = purge ]; then
6241 update-rc.d <var>package</var> remove
6243 </example>. Note that if your package changes runlevels
6244 or priority, you may have to remove and recreate the links,
6245 since otherwise the old links may persist. Refer to the
6246 documentation of <prgn>update-rc.d</prgn>.
6250 This will use a default sequence number of 20. If it does
6251 not matter when or in which order the <file>init.d</file>
6252 script is run, use this default. If it does, then you
6253 should talk to the maintainer of the <prgn>sysvinit</prgn>
6254 package or post to <tt>debian-devel</tt>, and they will
6255 help you choose a number.
6259 For more information about using <tt>update-rc.d</tt>,
6260 please consult its man page <manref name="update-rc.d"
6266 <heading>Running initscripts</heading>
6268 The program <prgn>invoke-rc.d</prgn> is provided to make
6269 it easier for package maintainers to properly invoke an
6270 initscript, obeying runlevel and other locally-defined
6271 constraints that might limit a package's right to start,
6272 stop and otherwise manage services. This program may be
6273 used by maintainers in their packages' scripts.
6277 The package maintainer scripts must use
6278 <prgn>invoke-rc.d</prgn> to invoke the
6279 <file>/etc/init.d/*</file> initscripts, instead of
6280 calling them directly.
6284 By default, <prgn>invoke-rc.d</prgn> will pass any
6285 action requests (start, stop, reload, restart...) to the
6286 <file>/etc/init.d</file> script, filtering out requests
6287 to start or restart a service out of its intended
6292 Most packages will simply need to change:
6293 <example compact="compact">/etc/init.d/<package>
6294 <action></example> in their <prgn>postinst</prgn>
6295 and <prgn>prerm</prgn> scripts to:
6296 <example compact="compact">
6297 if which invoke-rc.d >/dev/null 2>&1; then
6298 invoke-rc.d <var>package</var> <action>
6300 /etc/init.d/<var>package</var> <action>
6306 A package should register its initscript services using
6307 <prgn>update-rc.d</prgn> before it tries to invoke them
6308 using <prgn>invoke-rc.d</prgn>. Invocation of
6309 unregistered services may fail.
6313 For more information about using
6314 <prgn>invoke-rc.d</prgn>, please consult its man page
6315 <manref name="invoke-rc.d" section="8">.
6321 <heading>Boot-time initialization</heading>
6324 There used to be another directory, <file>/etc/rc.boot</file>,
6325 which contained scripts which were run once per machine
6326 boot. This has been deprecated in favour of links from
6327 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6328 described in <ref id="/etc/init.d">. Packages must not
6329 place files in <file>/etc/rc.boot</file>.
6334 <heading>Example</heading>
6337 An example on which you can base your
6338 <file>/etc/init.d</file> scripts is found in
6339 <file>/etc/init.d/skeleton</file>.
6346 <heading>Console messages from <file>init.d</file> scripts</heading>
6349 This section describes the formats to be used for messages
6350 written to standard output by the <file>/etc/init.d</file>
6351 scripts. The intent is to improve the consistency of
6352 Debian's startup and shutdown look and feel. For this
6353 reason, please look very carefully at the details. We want
6354 the messages to have the same format in terms of wording,
6355 spaces, punctuation and case of letters.
6359 Here is a list of overall rules that should be used for
6360 messages generated by <file>/etc/init.d</file> scripts.
6366 The message should fit in one line (fewer than 80
6367 characters), start with a capital letter and end with
6368 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6372 If the script is performing some time consuming task in
6373 the background (not merely starting or stopping a
6374 program, for instance), an ellipsis (three dots:
6375 <tt>...</tt>) should be output to the screen, with no
6376 leading or tailing whitespace or line feeds.
6380 The messages should appear as if the computer is telling
6381 the user what it is doing (politely :-), but should not
6382 mention "it" directly. For example, instead of:
6383 <example compact="compact">
6384 I'm starting network daemons: nfsd mountd.
6386 the message should say
6387 <example compact="compact">
6388 Starting network daemons: nfsd mountd.
6395 <tt>init.d</tt> script should use the following standard
6396 message formats for the situations enumerated below.
6402 <p>When daemons are started</p>
6405 If the script starts one or more daemons, the output
6406 should look like this (a single line, no leading
6408 <example compact="compact">
6409 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6411 The <var>description</var> should describe the
6412 subsystem the daemon or set of daemons are part of,
6413 while <var>daemon-1</var> up to <var>daemon-n</var>
6414 denote each daemon's name (typically the file name of
6419 For example, the output of <file>/etc/init.d/lpd</file>
6421 <example compact="compact">
6422 Starting printer spooler: lpd.
6427 This can be achieved by saying
6428 <example compact="compact">
6429 echo -n "Starting printer spooler: lpd"
6430 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6433 in the script. If there are more than one daemon to
6434 start, the output should look like this:
6435 <example compact="compact">
6436 echo -n "Starting remote file system services:"
6437 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6438 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6439 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6442 This makes it possible for the user to see what is
6443 happening and when the final daemon has been started.
6444 Care should be taken in the placement of white spaces:
6445 in the example above the system administrators can
6446 easily comment out a line if they don't want to start
6447 a specific daemon, while the displayed message still
6453 <p>When a system parameter is being set</p>
6456 If you have to set up different system parameters
6457 during the system boot, you should use this format:
6458 <example compact="compact">
6459 Setting <var>parameter</var> to "<var>value</var>".
6464 You can use a statement such as the following to get
6466 <example compact="compact">
6467 echo "Setting DNS domainname to \"$domainname\"."
6472 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6473 for the left and right quotation marks. A grave accent
6474 (<tt>`</tt>) is not a quote character; neither is an
6475 apostrophe (<tt>'</tt>).
6480 <p>When a daemon is stopped or restarted</p>
6483 When you stop or restart a daemon, you should issue a
6484 message identical to the startup message, except that
6485 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6486 or <tt>Restarting</tt> respectively.
6490 For example, stopping the printer daemon will look like
6492 <example compact="compact">
6493 Stopping printer spooler: lpd.
6499 <p>When something is executed</p>
6502 There are several examples where you have to run a
6503 program at system startup or shutdown to perform a
6504 specific task, for example, setting the system's clock
6505 using <prgn>netdate</prgn> or killing all processes
6506 when the system shuts down. Your message should look
6508 <example compact="compact">
6509 Doing something very useful...done.
6511 You should print the <tt>done.</tt> immediately after
6512 the job has been completed, so that the user is
6513 informed why they have to wait. You can get this
6515 <example compact="compact">
6516 echo -n "Doing something very useful..."
6525 <p>When the configuration is reloaded</p>
6528 When a daemon is forced to reload its configuration
6529 files you should use the following format:
6530 <example compact="compact">
6531 Reloading <var>description</var> configuration...done.
6533 where <var>description</var> is the same as in the
6534 daemon starting message.
6542 <heading>Cron jobs</heading>
6545 Packages must not modify the configuration file
6546 <file>/etc/crontab</file>, and they must not modify the files in
6547 <file>/var/spool/cron/crontabs</file>.</p>
6550 If a package wants to install a job that has to be executed
6551 via cron, it should place a file with the name of the
6552 package in one or more of the following directories:
6553 <example compact="compact">
6559 As these directory names imply, the files within them are
6560 executed on an hourly, daily, weekly, or monthly basis,
6561 respectively. The exact times are listed in
6562 <file>/etc/crontab</file>.</p>
6565 All files installed in any of these directories must be
6566 scripts (e.g., shell scripts or Perl scripts) so that they
6567 can easily be modified by the local system administrator.
6568 In addition, they must be treated as configuration files.
6572 If a certain job has to be executed at some other frequency or
6573 at a specific time, the package should install a file
6574 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6575 same syntax as <file>/etc/crontab</file> and is processed by
6576 <prgn>cron</prgn> automatically. The file must also be
6577 treated as a configuration file. (Note that entries in the
6578 <file>/etc/cron.d</file> directory are not handled by
6579 <prgn>anacron</prgn>. Thus, you should only use this
6580 directory for jobs which may be skipped if the system is not
6584 The scripts or crontab entries in these directories should
6585 check if all necessary programs are installed before they
6586 try to execute them. Otherwise, problems will arise when a
6587 package was removed but not purged since configuration files
6588 are kept on the system in this situation.</p>
6592 <heading>Menus</heading>
6595 The Debian <tt>menu</tt> package provides a standard
6596 interface between packages providing applications and
6597 <em>menu programs</em> (either X window managers or
6598 text-based menu programs such as <prgn>pdmenu</prgn>).
6602 All packages that provide applications that need not be
6603 passed any special command line arguments for normal
6604 operation should register a menu entry for those
6605 applications, so that users of the <tt>menu</tt> package
6606 will automatically get menu entries in their window
6607 managers, as well in shells like <tt>pdmenu</tt>.
6611 Menu entries should follow the current menu policy.
6615 The menu policy can be found in the <tt>menu-policy</tt>
6616 files in the <tt>debian-policy</tt> package.
6617 It is also available from the Debian web mirrors at
6618 <tt><url name="/doc/packaging-manuals/menu-policy/"
6619 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6623 Please also refer to the <em>Debian Menu System</em>
6624 documentation that comes with the <package>menu</package>
6625 package for information about how to register your
6631 <heading>Multimedia handlers</heading>
6634 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6635 is a mechanism for encoding files and data streams and
6636 providing meta-information about them, in particular their
6637 type (e.g. audio or video) and format (e.g. PNG, HTML,
6642 Registration of MIME type handlers allows programs like mail
6643 user agents and web browsers to invoke these handlers to
6644 view, edit or display MIME types they don't support directly.
6648 Packages which provide the ability to view/show/play,
6649 compose, edit or print MIME types should register themselves
6650 as such following the current MIME support policy.
6654 The MIME support policy can be found in the <tt>mime-policy</tt>
6655 files in the <tt>debian-policy</tt> package.
6656 It is also available from the Debian web mirrors at
6657 <tt><url name="/doc/packaging-manuals/mime-policy/"
6658 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6664 <heading>Keyboard configuration</heading>
6667 To achieve a consistent keyboard configuration so that all
6668 applications interpret a keyboard event the same way, all
6669 programs in the Debian distribution must be configured to
6670 comply with the following guidelines.
6674 The following keys must have the specified interpretations:
6677 <tag><tt><--</tt></tag>
6678 <item>delete the character to the left of the cursor</item>
6680 <tag><tt>Delete</tt></tag>
6681 <item>delete the character to the right of the cursor</item>
6683 <tag><tt>Control+H</tt></tag>
6684 <item>emacs: the help prefix</item>
6687 The interpretation of any keyboard events should be
6688 independent of the terminal that is used, be it a virtual
6689 console, an X terminal emulator, an rlogin/telnet session,
6694 The following list explains how the different programs
6695 should be set up to achieve this:
6701 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6705 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6709 X translations are set up to make
6710 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6711 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6712 is the vt220 escape code for the "delete character"
6713 key). This must be done by loading the X resources
6714 using <prgn>xrdb</prgn> on all local X displays, not
6715 using the application defaults, so that the
6716 translation resources used correspond to the
6717 <prgn>xmodmap</prgn> settings.
6721 The Linux console is configured to make
6722 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6723 generate <tt>ESC [ 3 ~</tt>.
6727 X applications are configured so that <tt><</tt>
6728 deletes left, and <tt>Delete</tt> deletes right. Motif
6729 applications already work like this.
6733 Terminals should have <tt>stty erase ^?</tt> .
6737 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6738 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6739 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6743 Emacs is programmed to map <tt>KB_Backspace</tt> or
6744 the <tt>stty erase</tt> character to
6745 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6746 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6747 <tt>^H</tt> to <tt>help</tt> as always.
6751 Other applications use the <tt>stty erase</tt>
6752 character and <tt>kdch1</tt> for the two delete keys,
6753 with ASCII DEL being "delete previous character" and
6754 <tt>kdch1</tt> being "delete character under
6762 This will solve the problem except for the following
6769 Some terminals have a <tt><--</tt> key that cannot
6770 be made to produce anything except <tt>^H</tt>. On
6771 these terminals Emacs help will be unavailable on
6772 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6773 character takes precedence in Emacs, and has been set
6774 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6775 available) can be used instead.
6779 Some operating systems use <tt>^H</tt> for <tt>stty
6780 erase</tt>. However, modern telnet versions and all
6781 rlogin versions propagate <tt>stty</tt> settings, and
6782 almost all UNIX versions honour <tt>stty erase</tt>.
6783 Where the <tt>stty</tt> settings are not propagated
6784 correctly, things can be made to work by using
6785 <tt>stty</tt> manually.
6789 Some systems (including previous Debian versions) use
6790 <prgn>xmodmap</prgn> to arrange for both
6791 <tt><--</tt> and <tt>Delete</tt> to generate
6792 <tt>KB_Delete</tt>. We can change the behavior of
6793 their X clients using the same X resources that we use
6794 to do it for our own clients, or configure our clients
6795 using their resources when things are the other way
6796 around. On displays configured like this
6797 <tt>Delete</tt> will not work, but <tt><--</tt>
6802 Some operating systems have different <tt>kdch1</tt>
6803 settings in their <tt>terminfo</tt> database for
6804 <tt>xterm</tt> and others. On these systems the
6805 <tt>Delete</tt> key will not work correctly when you
6806 log in from a system conforming to our policy, but
6807 <tt><--</tt> will.
6814 <heading>Environment variables</heading>
6817 A program must not depend on environment variables to get
6818 reasonable defaults. (That's because these environment
6819 variables would have to be set in a system-wide
6820 configuration file like <file>/etc/profile</file>, which is not
6821 supported by all shells.)
6825 If a program usually depends on environment variables for its
6826 configuration, the program should be changed to fall back to
6827 a reasonable default configuration if these environment
6828 variables are not present. If this cannot be done easily
6829 (e.g., if the source code of a non-free program is not
6830 available), the program must be replaced by a small
6831 "wrapper" shell script which sets the environment variables
6832 if they are not already defined, and calls the original program.
6836 Here is an example of a wrapper script for this purpose:
6838 <example compact="compact">
6840 BAR=${BAR:-/var/lib/fubar}
6842 exec /usr/lib/foo/foo "$@"
6847 Furthermore, as <file>/etc/profile</file> is a configuration
6848 file of the <prgn>base-files</prgn> package, other packages must
6849 not put any environment variables or other commands into that
6854 <sect id="doc-base">
6855 <heading>Registering Documents using doc-base</heading>
6858 The <package>doc-base</package> package implements a
6859 flexible mechanism for handling and presenting
6860 documentation. The recommended practice is for every Debian
6861 package that provides online documentation (other than just
6862 manual pages) to register these documents with
6863 <package>doc-base</package> by installing a
6864 <package>doc-base</package> control file via the
6865 <prgn/install-docs/ script at installation time and
6866 de-register the manuals again when the package is removed.
6869 Please refer to the documentation that comes with the
6870 <package>doc-base</package> package for information and
6879 <heading>Files</heading>
6882 <heading>Binaries</heading>
6885 Two different packages must not install programs with
6886 different functionality but with the same filenames. (The
6887 case of two programs having the same functionality but
6888 different implementations is handled via "alternatives" or
6889 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6890 <ref id="conflicts"> respectively.) If this case happens,
6891 one of the programs must be renamed. The maintainers should
6892 report this to the <tt>debian-devel</tt> mailing list and
6893 try to find a consensus about which program will have to be
6894 renamed. If a consensus cannot be reached, <em>both</em>
6895 programs must be renamed.
6899 By default, when a package is being built, any binaries
6900 created should include debugging information, as well as
6901 being compiled with optimization. You should also turn on
6902 as many reasonable compilation warnings as possible; this
6903 makes life easier for porters, who can then look at build
6904 logs for possible problems. For the C programming language,
6905 this means the following compilation parameters should be
6907 <example compact="compact">
6909 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6911 INSTALL = install -s # (or use strip on the files in debian/tmp)
6916 Note that by default all installed binaries should be stripped,
6917 either by using the <tt>-s</tt> flag to
6918 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6919 the binaries after they have been copied into
6920 <file>debian/tmp</file> but before the tree is made into a
6925 Although binaries in the build tree should be compiled with
6926 debugging information by default, it can often be difficult to
6927 debug programs if they are also subjected to compiler
6928 optimization. For this reason, it is recommended to support the
6929 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6930 (see <ref id="debianrules-options">). This variable can contain
6931 several flags to change how a package is compiled and built.
6935 It is up to the package maintainer to decide what
6936 compilation options are best for the package. Certain
6937 binaries (such as computationally-intensive programs) will
6938 function better with certain flags (<tt>-O3</tt>, for
6939 example); feel free to use them. Please use good judgment
6940 here. Don't use flags for the sake of it; only use them
6941 if there is good reason to do so. Feel free to override
6942 the upstream author's ideas about which compilation
6943 options are best: they are often inappropriate for our
6949 <sect id="libraries">
6950 <heading>Libraries</heading>
6953 If the package is <strong>architecture: any</strong>, then
6954 the shared library compilation and linking flags must have
6955 <tt>-fPIC</tt>, or the package shall not build on some of
6956 the supported architectures<footnote>
6958 If you are using GCC, <tt>-fPIC</tt> produces code with
6959 relocatable position independent code, which is required for
6960 most architectures to create a shared library, with i386 and
6961 perhaps some others where non position independent code is
6962 permitted in a shared library.
6965 Position independent code may have a performance penalty,
6966 especially on <tt>i386</tt>. However, in most cases the
6967 speed penalty must be measured against the memory wasted on
6968 the few architectures where non position independent code is
6971 </footnote>. Any exception to this rule must be discussed on
6972 the mailing list <em>debian-devel@lists.debian.org</em>, and
6973 a rough consensus obtained. The reasons for not compiling
6974 with <tt>-fPIC</tt> flag must be recorded in the file
6975 <tt>README.Debian</tt>, and care must be taken to either
6976 restrict the architecture or arrange for <tt>-fPIC</tt> to
6977 be used on architectures where it is required.<footnote>
6979 Some of the reasons why this might be required is if the
6980 library contains hand crafted assembly code that is not
6981 relocatable, the speed penalty is excessive for compute
6982 intensive libs, and similar reasons.
6987 As to the static libraries, the common case is not to have
6988 relocatable code, since there is no benefit, unless in specific
6989 cases; therefore the static version must not be compiled
6990 with the <tt>-fPIC</tt> flag. Any exception to this rule
6991 should be discussed on the mailing list
6992 <em>debian-devel@lists.debian.org</em>, and the reasons for
6993 compiling with the <tt>-fPIC</tt> flag must be recorded in
6994 the file <tt>README.Debian</tt>. <footnote>
6996 Some of the reasons for linking static libraries with
6997 the <tt>-fPIC</tt> flag are if, for example, one needs a
6998 Perl API for a library that is under rapid development,
6999 and has an unstable API, so shared libraries are
7000 pointless at this phase of the library's development. In
7001 that case, since Perl needs a library with relocatable
7002 code, it may make sense to create a static library with
7003 relocatable code. Another reason cited is if you are
7004 distilling various libraries into a common shared
7005 library, like <tt>mklibs</tt> does in the Debian
7011 In other words, if both a shared and a static library is
7012 being built, each source unit (<tt>*.c</tt>, for example,
7013 for C files) will need to be compiled twice, for the normal
7017 You must specify the gcc option <tt>-D_REENTRANT</tt>
7018 when building a library (either static or shared) to make
7019 the library compatible with LinuxThreads.
7023 Although not enforced by the build tools, shared libraries
7024 must be linked against all libraries that they use symbols from
7025 in the same way that binaries are. This ensures the correct
7026 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7027 system and guarantees that all libraries can be safely opened
7028 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7029 option <tt>-Wl,-z,defs</tt> when building a shared library.
7030 Since this option enforces symbol resolution at build time,
7031 a missing library reference will be caught early as a fatal
7036 All installed shared libraries should be stripped with
7037 <example compact="compact">
7038 strip --strip-unneeded <var>your-lib</var>
7040 (The option <tt>--strip-unneeded</tt> makes
7041 <prgn>strip</prgn> remove only the symbols which aren't
7042 needed for relocation processing.) Shared libraries can
7043 function perfectly well when stripped, since the symbols for
7044 dynamic linking are in a separate part of the ELF object
7046 You might also want to use the options
7047 <tt>--remove-section=.comment</tt> and
7048 <tt>--remove-section=.note</tt> on both shared libraries
7049 and executables, and <tt>--strip-debug</tt> on static
7055 Note that under some circumstances it may be useful to
7056 install a shared library unstripped, for example when
7057 building a separate package to support debugging.
7061 Shared object files (often <file>.so</file> files) that are not
7062 public libraries, that is, they are not meant to be linked
7063 to by third party executables (binaries of other packages),
7064 should be installed in subdirectories of the
7065 <file>/usr/lib</file> directory. Such files are exempt from the
7066 rules that govern ordinary shared libraries, except that
7067 they must not be installed executable and should be
7069 A common example are the so-called "plug-ins",
7070 internal shared objects that are dynamically loaded by
7071 programs using <manref name="dlopen" section="3">.
7076 An ever increasing number of packages are using
7077 <prgn>libtool</prgn> to do their linking. The latest GNU
7078 libtools (>= 1.3a) can take advantage of the metadata in the
7079 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7080 files). The main advantage of <prgn>libtool</prgn>'s
7081 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7082 store and subsequently access metadata with respect to the
7083 libraries it builds. <prgn>libtool</prgn> will search for
7084 those files, which contain a lot of useful information about
7085 a library (such as library dependency information for static
7086 linking). Also, they're <em>essential</em> for programs
7087 using <tt>libltdl</tt>.<footnote>
7088 Although <prgn>libtool</prgn> is fully capable of
7089 linking against shared libraries which don't have
7090 <tt>.la</tt> files, as it is a mere shell script it can
7091 add considerably to the build time of a
7092 <prgn>libtool</prgn>-using package if that shell script
7093 has to derive all this information from first principles
7094 for each library every time it is linked. With the
7095 advent of <prgn>libtool</prgn> version 1.4 (and to a
7096 lesser extent <prgn>libtool</prgn> version 1.3), the
7097 <file>.la</file> files also store information about
7098 inter-library dependencies which cannot necessarily be
7099 derived after the <file>.la</file> file is deleted.
7104 Packages that use <prgn>libtool</prgn> to create shared
7105 libraries should include the <file>.la</file> files in the
7106 <tt>-dev</tt> package, unless the package relies on
7107 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7108 the <tt>.la</tt> files must go in the run-time library
7113 You must make sure that you use only released versions of
7114 shared libraries to build your packages; otherwise other
7115 users will not be able to run your binaries
7116 properly. Producing source packages that depend on
7117 unreleased compilers is also usually a bad
7124 <heading>Shared libraries</heading>
7126 This section has moved to <ref id="sharedlibs">.
7132 <heading>Scripts</heading>
7135 All command scripts, including the package maintainer
7136 scripts inside the package and used by <prgn>dpkg</prgn>,
7137 should have a <tt>#!</tt> line naming the shell to be used
7142 In the case of Perl scripts this should be
7143 <tt>#!/usr/bin/perl</tt>.
7147 When scripts are installed into a directory in the system
7148 PATH, the script name should not include an extension such
7149 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7150 language currently used to implement it.
7153 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7154 should almost certainly start with <tt>set -e</tt> so that
7155 errors are detected. Every script should use
7156 <tt>set -e</tt> or check the exit status of <em>every</em>
7161 Scripts may assume that <file>/bin/sh</file> implements the
7162 SUSv3 Shell Command Language<footnote>
7163 Single UNIX Specification, version 3, which is also IEEE
7164 1003.1-2004 (POSIX), and is available on the World Wide Web
7165 from <url id="http://www.unix.org/version3/online.html"
7166 name="The Open Group"> after free
7167 registration.</footnote>
7168 plus the following additional features not mandated by
7170 These features are in widespread use in the Linux community
7171 and are implemented in all of bash, dash, and ksh, the most
7172 common shells users may wish to use as <file>/bin/sh</file>.
7175 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7176 must not generate a newline.</item>
7177 <item><tt>test</tt>, if implemented as a shell built-in, must
7178 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7180 <item><tt>local</tt> to create a scoped variable must be
7181 supported, including listing multiple variables in a single
7182 local command and assigning a value to a variable at the
7183 same time as localizing it. <tt>local</tt> may or
7184 may not preserve the variable value from an outer scope if
7185 no assignment is present. Uses such as:
7189 # ... use a, b, c, d ...
7192 must be supported and must set the value of <tt>c</tt> to
7196 If a shell script requires non-SUSv3 features from the shell
7197 interpreter other than those listed above, the appropriate shell
7198 must be specified in the first line of the script (e.g.,
7199 <tt>#!/bin/bash</tt>) and the package must depend on the package
7200 providing the shell (unless the shell package is marked
7201 "Essential", as in the case of <prgn>bash</prgn>).
7205 You may wish to restrict your script to SUSv3 features plus the
7206 above set when possible so that it may use <file>/bin/sh</file>
7207 as its interpreter. If your script works with <prgn>dash</prgn>
7208 (originally called <prgn>ash</prgn>), it probably complies with
7209 the above requirements, but if you are in doubt, use
7210 <file>/bin/bash</file>.
7214 Perl scripts should check for errors when making any
7215 system calls, including <tt>open</tt>, <tt>print</tt>,
7216 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7220 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7221 scripting languages. See <em>Csh Programming Considered
7222 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7223 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7224 If an upstream package comes with <prgn>csh</prgn> scripts
7225 then you must make sure that they start with
7226 <tt>#!/bin/csh</tt> and make your package depend on the
7227 <prgn>c-shell</prgn> virtual package.
7231 Any scripts which create files in world-writeable
7232 directories (e.g., in <file>/tmp</file>) must use a
7233 mechanism which will fail atomically if a file with the same
7234 name already exists.
7238 The Debian base system provides the <prgn>tempfile</prgn>
7239 and <prgn>mktemp</prgn> utilities for use by scripts for
7246 <heading>Symbolic links</heading>
7249 In general, symbolic links within a top-level directory
7250 should be relative, and symbolic links pointing from one
7251 top-level directory into another should be absolute. (A
7252 top-level directory is a sub-directory of the root
7253 directory <file>/</file>.)
7257 In addition, symbolic links should be specified as short as
7258 possible, i.e., link targets like <file>foo/../bar</file> are
7263 Note that when creating a relative link using
7264 <prgn>ln</prgn> it is not necessary for the target of the
7265 link to exist relative to the working directory you're
7266 running <prgn>ln</prgn> from, nor is it necessary to change
7267 directory to the directory where the link is to be made.
7268 Simply include the string that should appear as the target
7269 of the link (this will be a pathname relative to the
7270 directory in which the link resides) as the first argument
7275 For example, in your <prgn>Makefile</prgn> or
7276 <file>debian/rules</file>, you can do things like:
7277 <example compact="compact">
7278 ln -fs gcc $(prefix)/bin/cc
7279 ln -fs gcc debian/tmp/usr/bin/cc
7280 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7281 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7286 A symbolic link pointing to a compressed file should always
7287 have the same file extension as the referenced file. (For
7288 example, if a file <file>foo.gz</file> is referenced by a
7289 symbolic link, the filename of the link has to end with
7290 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7295 <heading>Device files</heading>
7298 Packages must not include device files in the package file
7303 If a package needs any special device files that are not
7304 included in the base system, it must call
7305 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7306 after notifying the user<footnote>
7307 This notification could be done via a (low-priority)
7308 debconf message, or an echo (printf) statement.
7313 Packages must not remove any device files in the
7314 <prgn>postrm</prgn> or any other script. This is left to the
7315 system administrator.
7319 Debian uses the serial devices
7320 <file>/dev/ttyS*</file>. Programs using the old
7321 <file>/dev/cu*</file> devices should be changed to use
7322 <file>/dev/ttyS*</file>.
7326 <sect id="config-files">
7327 <heading>Configuration files</heading>
7330 <heading>Definitions</heading>
7334 <tag>configuration file</tag>
7336 A file that affects the operation of a program, or
7337 provides site- or host-specific information, or
7338 otherwise customizes the behavior of a program.
7339 Typically, configuration files are intended to be
7340 modified by the system administrator (if needed or
7341 desired) to conform to local policy or to provide
7342 more useful site-specific behavior.
7345 <tag><tt>conffile</tt></tag>
7347 A file listed in a package's <tt>conffiles</tt>
7348 file, and is treated specially by <prgn>dpkg</prgn>
7349 (see <ref id="configdetails">).
7355 The distinction between these two is important; they are
7356 not interchangeable concepts. Almost all
7357 <tt>conffile</tt>s are configuration files, but many
7358 configuration files are not <tt>conffiles</tt>.
7362 As noted elsewhere, <file>/etc/init.d</file> scripts,
7363 <file>/etc/default</file> files, scripts installed in
7364 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7365 configuration installed in <file>/etc/cron.d</file> must be
7366 treated as configuration files. In general, any script that
7367 embeds configuration information is de-facto a configuration
7368 file and should be treated as such.
7373 <heading>Location</heading>
7376 Any configuration files created or used by your package
7377 must reside in <file>/etc</file>. If there are several,
7378 consider creating a subdirectory of <file>/etc</file>
7379 named after your package.
7383 If your package creates or uses configuration files
7384 outside of <file>/etc</file>, and it is not feasible to modify
7385 the package to use <file>/etc</file> directly, put the files
7386 in <file>/etc</file> and create symbolic links to those files
7387 from the location that the package requires.
7392 <heading>Behavior</heading>
7395 Configuration file handling must conform to the following
7397 <list compact="compact">
7399 local changes must be preserved during a package
7403 configuration files must be preserved when the
7404 package is removed, and only deleted when the
7411 The easy way to achieve this behavior is to make the
7412 configuration file a <tt>conffile</tt>. This is
7413 appropriate only if it is possible to distribute a default
7414 version that will work for most installations, although
7415 some system administrators may choose to modify it. This
7416 implies that the default version will be part of the
7417 package distribution, and must not be modified by the
7418 maintainer scripts during installation (or at any other
7423 In order to ensure that local changes are preserved
7424 correctly, no package may contain or make hard links to
7425 conffiles.<footnote>
7426 Rationale: There are two problems with hard links.
7427 The first is that some editors break the link while
7428 editing one of the files, so that the two files may
7429 unwittingly become unlinked and different. The second
7430 is that <prgn>dpkg</prgn> might break the hard link
7431 while upgrading <tt>conffile</tt>s.
7436 The other way to do it is via the maintainer scripts. In
7437 this case, the configuration file must not be listed as a
7438 <tt>conffile</tt> and must not be part of the package
7439 distribution. If the existence of a file is required for
7440 the package to be sensibly configured it is the
7441 responsibility of the package maintainer to provide
7442 maintainer scripts which correctly create, update and
7443 maintain the file and remove it on purge. (See <ref
7444 id="maintainerscripts"> for more information.) These
7445 scripts must be idempotent (i.e., must work correctly if
7446 <prgn>dpkg</prgn> needs to re-run them due to errors
7447 during installation or removal), must cope with all the
7448 variety of ways <prgn>dpkg</prgn> can call maintainer
7449 scripts, must not overwrite or otherwise mangle the user's
7450 configuration without asking, must not ask unnecessary
7451 questions (particularly during upgrades), and must
7452 otherwise be good citizens.
7456 The scripts are not required to configure every possible
7457 option for the package, but only those necessary to get
7458 the package running on a given system. Ideally the
7459 sysadmin should not have to do any configuration other
7460 than that done (semi-)automatically by the
7461 <prgn>postinst</prgn> script.
7465 A common practice is to create a script called
7466 <file><var>package</var>-configure</file> and have the
7467 package's <prgn>postinst</prgn> call it if and only if the
7468 configuration file does not already exist. In certain
7469 cases it is useful for there to be an example or template
7470 file which the maintainer scripts use. Such files should
7471 be in <file>/usr/share/<var>package</var></file> or
7472 <file>/usr/lib/<var>package</var></file> (depending on whether
7473 they are architecture-independent or not). There should
7474 be symbolic links to them from
7475 <file>/usr/share/doc/<var>package</var>/examples</file> if
7476 they are examples, and should be perfectly ordinary
7477 <prgn>dpkg</prgn>-handled files (<em>not</em>
7478 configuration files).
7482 These two styles of configuration file handling must
7483 not be mixed, for that way lies madness:
7484 <prgn>dpkg</prgn> will ask about overwriting the file
7485 every time the package is upgraded.
7490 <heading>Sharing configuration files</heading>
7493 Packages which specify the same file as a
7494 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7495 with each other. (This is an instance of the general rule
7496 about not sharing files. Note that neither alternatives
7497 nor diversions are likely to be appropriate in this case;
7498 in particular, <prgn>dpkg</prgn> does not handle diverted
7499 <tt>conffile</tt>s well.)
7503 The maintainer scripts must not alter a <tt>conffile</tt>
7504 of <em>any</em> package, including the one the scripts
7509 If two or more packages use the same configuration file
7510 and it is reasonable for both to be installed at the same
7511 time, one of these packages must be defined as
7512 <em>owner</em> of the configuration file, i.e., it will be
7513 the package which handles that file as a configuration
7514 file. Other packages that use the configuration file must
7515 depend on the owning package if they require the
7516 configuration file to operate. If the other package will
7517 use the configuration file if present, but is capable of
7518 operating without it, no dependency need be declared.
7522 If it is desirable for two or more related packages to
7523 share a configuration file <em>and</em> for all of the
7524 related packages to be able to modify that configuration
7525 file, then the following should be done:
7526 <enumlist compact="compact">
7528 One of the related packages (the "owning" package)
7529 will manage the configuration file with maintainer
7530 scripts as described in the previous section.
7533 The owning package should also provide a program
7534 that the other packages may use to modify the
7538 The related packages must use the provided program
7539 to make any desired modifications to the
7540 configuration file. They should either depend on
7541 the core package to guarantee that the configuration
7542 modifier program is available or accept gracefully
7543 that they cannot modify the configuration file if it
7544 is not. (This is in addition to the fact that the
7545 configuration file may not even be present in the
7552 Sometimes it's appropriate to create a new package which
7553 provides the basic infrastructure for the other packages
7554 and which manages the shared configuration files. (The
7555 <tt>sgml-base</tt> package is a good example.)
7560 <heading>User configuration files ("dotfiles")</heading>
7563 The files in <file>/etc/skel</file> will automatically be
7564 copied into new user accounts by <prgn>adduser</prgn>.
7565 No other program should reference the files in
7566 <file>/etc/skel</file>.
7570 Therefore, if a program needs a dotfile to exist in
7571 advance in <file>$HOME</file> to work sensibly, that dotfile
7572 should be installed in <file>/etc/skel</file> and treated as a
7577 However, programs that require dotfiles in order to
7578 operate sensibly are a bad thing, unless they do create
7579 the dotfiles themselves automatically.
7583 Furthermore, programs should be configured by the Debian
7584 default installation to behave as closely to the upstream
7585 default behavior as possible.
7589 Therefore, if a program in a Debian package needs to be
7590 configured in some way in order to operate sensibly, that
7591 should be done using a site-wide configuration file placed
7592 in <file>/etc</file>. Only if the program doesn't support a
7593 site-wide default configuration and the package maintainer
7594 doesn't have time to add it may a default per-user file be
7595 placed in <file>/etc/skel</file>.
7599 <file>/etc/skel</file> should be as empty as we can make it.
7600 This is particularly true because there is no easy (or
7601 necessarily desirable) mechanism for ensuring that the
7602 appropriate dotfiles are copied into the accounts of
7603 existing users when a package is installed.
7609 <heading>Log files</heading>
7611 Log files should usually be named
7612 <file>/var/log/<var>package</var>.log</file>. If you have many
7613 log files, or need a separate directory for permission
7614 reasons (<file>/var/log</file> is writable only by
7615 <file>root</file>), you should usually create a directory named
7616 <file>/var/log/<var>package</var></file> and place your log
7621 Log files must be rotated occasionally so that they don't
7622 grow indefinitely; the best way to do this is to drop a log
7623 rotation configuration file into the directory
7624 <file>/etc/logrotate.d</file> and use the facilities provided by
7625 logrotate.<footnote>
7627 The traditional approach to log files has been to set up
7628 <em>ad hoc</em> log rotation schemes using simple shell
7629 scripts and cron. While this approach is highly
7630 customizable, it requires quite a lot of sysadmin work.
7631 Even though the original Debian system helped a little
7632 by automatically installing a system which can be used
7633 as a template, this was deemed not enough.
7637 The use of <prgn>logrotate</prgn>, a program developed
7638 by Red Hat, is better, as it centralizes log management.
7639 It has both a configuration file
7640 (<file>/etc/logrotate.conf</file>) and a directory where
7641 packages can drop their individual log rotation
7642 configurations (<file>/etc/logrotate.d</file>).
7645 Here is a good example for a logrotate config
7646 file (for more information see <manref name="logrotate"
7648 <example compact="compact">
7649 /var/log/foo/*.log {
7654 /etc/init.d/foo force-reload
7658 This rotates all files under <file>/var/log/foo</file>, saves 12
7659 compressed generations, and forces the daemon to reload its
7660 configuration information after the log rotation.
7664 Log files should be removed when the package is
7665 purged (but not when it is only removed). This should be
7666 done by the <prgn>postrm</prgn> script when it is called
7667 with the argument <tt>purge</tt> (see <ref
7668 id="removedetails">).
7673 <heading>Permissions and owners</heading>
7676 The rules in this section are guidelines for general use.
7677 If necessary you may deviate from the details below.
7678 However, if you do so you must make sure that what is done
7679 is secure and you should try to be as consistent as possible
7680 with the rest of the system. You should probably also
7681 discuss it on <prgn>debian-devel</prgn> first.
7685 Files should be owned by <tt>root:root</tt>, and made
7686 writable only by the owner and universally readable (and
7687 executable, if appropriate), that is mode 644 or 755.
7691 Directories should be mode 755 or (for group-writability)
7692 mode 2775. The ownership of the directory should be
7693 consistent with its mode: if a directory is mode 2775, it
7694 should be owned by the group that needs write access to
7697 When a package is upgraded, and the owner or permissions
7698 of a file included in the package has changed, dpkg
7699 arranges for the ownership and permissions to be
7700 correctly set upon installation. However, this does not
7701 extend to directories; the permissions and ownership of
7702 directories already on the system does not change on
7703 install or upgrade of packages. This makes sense, since
7704 otherwise common directories like <tt>/usr</tt> would
7705 always be in flux. To correctly change permissions of a
7706 directory the package owns, explicit action is required,
7707 usually in the <tt>postinst</tt> script. Care must be
7708 taken to handle downgrades as well, in that case.
7715 Setuid and setgid executables should be mode 4755 or 2755
7716 respectively, and owned by the appropriate user or group.
7717 They should not be made unreadable (modes like 4711 or
7718 2711 or even 4111); doing so achieves no extra security,
7719 because anyone can find the binary in the freely available
7720 Debian package; it is merely inconvenient. For the same
7721 reason you should not restrict read or execute permissions
7722 on non-set-id executables.
7726 Some setuid programs need to be restricted to particular
7727 sets of users, using file permissions. In this case they
7728 should be owned by the uid to which they are set-id, and by
7729 the group which should be allowed to execute them. They
7730 should have mode 4754; again there is no point in making
7731 them unreadable to those users who must not be allowed to
7736 It is possible to arrange that the system administrator can
7737 reconfigure the package to correspond to their local
7738 security policy by changing the permissions on a binary:
7739 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7740 described below.<footnote>
7741 Ordinary files installed by <prgn>dpkg</prgn> (as
7742 opposed to <tt>conffile</tt>s and other similar objects)
7743 normally have their permissions reset to the distributed
7744 permissions when the package is reinstalled. However,
7745 the use of <prgn>dpkg-statoverride</prgn> overrides this
7746 default behavior. If you use this method, you should
7747 remember to describe <prgn>dpkg-statoverride</prgn> in
7748 the package documentation; being a relatively new
7749 addition to Debian, it is probably not yet well-known.
7751 Another method you should consider is to create a group for
7752 people allowed to use the program(s) and make any setuid
7753 executables executable only by that group.
7757 If you need to create a new user or group for your package
7758 there are two possibilities. Firstly, you may need to
7759 make some files in the binary package be owned by this
7760 user or group, or you may need to compile the user or
7761 group id (rather than just the name) into the binary
7762 (though this latter should be avoided if possible, as in
7763 this case you need a statically allocated id).</p>
7766 If you need a statically allocated id, you must ask for a
7767 user or group id from the <tt>base-passwd</tt> maintainer,
7768 and must not release the package until you have been
7769 allocated one. Once you have been allocated one you must
7770 either make the package depend on a version of the
7771 <tt>base-passwd</tt> package with the id present in
7772 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7773 your package to create the user or group itself with the
7774 correct id (using <tt>adduser</tt>) in its
7775 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7776 the <prgn>postinst</prgn> is to be preferred if it is
7777 possible, otherwise a pre-dependency will be needed on the
7778 <tt>adduser</tt> package.)
7782 On the other hand, the program might be able to determine
7783 the uid or gid from the user or group name at runtime, so
7784 that a dynamically allocated id can be used. In this case
7785 you should choose an appropriate user or group name,
7786 discussing this on <prgn>debian-devel</prgn> and checking
7787 with the <package/base-passwd/ maintainer that it is unique and that
7788 they do not wish you to use a statically allocated id
7789 instead. When this has been checked you must arrange for
7790 your package to create the user or group if necessary using
7791 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7792 <prgn>postinst</prgn> script (again, the latter is to be
7793 preferred if it is possible).
7797 Note that changing the numeric value of an id associated
7798 with a name is very difficult, and involves searching the
7799 file system for all appropriate files. You need to think
7800 carefully whether a static or dynamic id is required, since
7801 changing your mind later will cause problems.
7804 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7806 This section is not intended as policy, but as a
7807 description of the use of <prgn>dpkg-statoverride</prgn>.
7811 If a system administrator wishes to have a file (or
7812 directory or other such thing) installed with owner and
7813 permissions different from those in the distributed Debian
7814 package, they can use the <prgn>dpkg-statoverride</prgn>
7815 program to instruct <prgn>dpkg</prgn> to use the different
7816 settings every time the file is installed. Thus the
7817 package maintainer should distribute the files with their
7818 normal permissions, and leave it for the system
7819 administrator to make any desired changes. For example, a
7820 daemon which is normally required to be setuid root, but
7821 in certain situations could be used without being setuid,
7822 should be installed setuid in the <tt>.deb</tt>. Then the
7823 local system administrator can change this if they wish.
7824 If there are two standard ways of doing it, the package
7825 maintainer can use <tt>debconf</tt> to find out the
7826 preference, and call <prgn>dpkg-statoverride</prgn> in the
7827 maintainer script if necessary to accommodate the system
7828 administrator's choice. Care must be taken during
7829 upgrades to not override an existing setting.
7833 Given the above, <prgn>dpkg-statoverride</prgn> is
7834 essentially a tool for system administrators and would not
7835 normally be needed in the maintainer scripts. There is
7836 one type of situation, though, where calls to
7837 <prgn>dpkg-statoverride</prgn> would be needed in the
7838 maintainer scripts, and that involves packages which use
7839 dynamically allocated user or group ids. In such a
7840 situation, something like the following idiom can be very
7841 helpful in the package's <prgn>postinst</prgn>, where
7842 <tt>sysuser</tt> is a dynamically allocated id:
7844 for i in /usr/bin/foo /usr/sbin/bar
7846 # only do something when no setting exists
7847 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7849 #include: debconf processing, question about foo and bar
7850 if [ "$RET" = "true" ] ; then
7851 dpkg-statoverride --update --add sysuser root 4755 $i
7856 The corresponding code to remove the override when the package
7859 for i in /usr/bin/foo /usr/sbin/bar
7861 if dpkg-statoverride --list $i >/dev/null 2>&1
7863 dpkg-statoverride --remove $i
7873 <chapt id="customized-programs">
7874 <heading>Customized programs</heading>
7876 <sect id="arch-spec">
7877 <heading>Architecture specification strings</heading>
7880 If a program needs to specify an <em>architecture specification
7881 string</em> in some place, it should select one of the
7882 strings provided by <tt>dpkg-architecture -L</tt>. The
7883 strings are in the format
7884 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7885 is sometimes elided, as when the OS is Linux.<footnote>
7886 <p>Currently, the strings are:
7887 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7888 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7889 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7890 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7891 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7892 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7893 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7894 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7895 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7896 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7897 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7898 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7899 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7900 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7901 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7902 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7903 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7904 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7905 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7906 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7907 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7908 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7909 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7910 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7911 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7912 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7913 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7914 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7915 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7916 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7917 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7918 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7919 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7920 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7921 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7922 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7923 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7929 Note that we don't want to use
7930 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7931 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7932 since this would make our programs incompatible with other
7933 Linux distributions. We also don't use something like
7934 <tt><var>arch</var>-unknown-linux</tt>, since the
7935 <tt>unknown</tt> does not look very good.
7939 <sect id="arch-wildcard-spec">
7940 <heading>Architecture Wildcards</heading>
7943 A package may specify an architecture wildcard. Architecture
7944 wildcards are in the format <tt><var>os</var></tt>-any and
7945 any-<tt><var>cpu</var></tt>. <footnote>Internally, the package
7946 system normalizes the GNU triplets and the Debian
7947 arches into Debian arch triplets (which are kind of inverted GNU
7948 triplets). So when matching two Debian arch triplets, whenever an
7949 <var>any</var> is found it matches with anything on the other side,
7952 gnu-linux-i386 is matched by gnu-linux-any
7953 gnu-kfreebsd-amd64 is matched by any-any-amd64
7955 And for example <var>any</var> is normalized to <var>any-any-any</var>.
7961 <heading>Daemons</heading>
7964 The configuration files <file>/etc/services</file>,
7965 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7966 by the <prgn>netbase</prgn> package and must not be modified
7971 If a package requires a new entry in one of these files, the
7972 maintainer should get in contact with the
7973 <prgn>netbase</prgn> maintainer, who will add the entries
7974 and release a new version of the <prgn>netbase</prgn>
7979 The configuration file <file>/etc/inetd.conf</file> must not be
7980 modified by the package's scripts except via the
7981 <prgn>update-inetd</prgn> script or the
7982 <file>DebianNet.pm</file> Perl module. See their documentation
7983 for details on how to add entries.
7987 If a package wants to install an example entry into
7988 <file>/etc/inetd.conf</file>, the entry must be preceded with
7989 exactly one hash character (<tt>#</tt>). Such lines are
7990 treated as "commented out by user" by the
7991 <prgn>update-inetd</prgn> script and are not changed or
7992 activated during package updates.
7997 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8001 Some programs need to create pseudo-ttys. This should be done
8002 using Unix98 ptys if the C library supports it. The resulting
8003 program must not be installed setuid root, unless that
8004 is required for other functionality.
8008 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8009 <file>/var/log/lastlog</file> must be installed writable by
8010 group <tt>utmp</tt>. Programs which need to modify those
8011 files must be installed setgid <tt>utmp</tt>.
8016 <heading>Editors and pagers</heading>
8019 Some programs have the ability to launch an editor or pager
8020 program to edit or display a text document. Since there are
8021 lots of different editors and pagers available in the Debian
8022 distribution, the system administrator and each user should
8023 have the possibility to choose their preferred editor and
8028 In addition, every program should choose a good default
8029 editor/pager if none is selected by the user or system
8034 Thus, every program that launches an editor or pager must
8035 use the EDITOR or PAGER environment variable to determine
8036 the editor or pager the user wishes to use. If these
8037 variables are not set, the programs <file>/usr/bin/editor</file>
8038 and <file>/usr/bin/pager</file> should be used, respectively.
8042 These two files are managed through the <prgn>dpkg</prgn>
8043 "alternatives" mechanism. Thus every package providing an
8044 editor or pager must call the
8045 <prgn>update-alternatives</prgn> script to register these
8050 If it is very hard to adapt a program to make use of the
8051 EDITOR or PAGER variables, that program may be configured to
8052 use <file>/usr/bin/sensible-editor</file> and
8053 <file>/usr/bin/sensible-pager</file> as the editor or pager
8054 program respectively. These are two scripts provided in the
8055 <package>sensible-utils</package> package that check the EDITOR
8056 and PAGER variables and launch the appropriate program, and fall
8057 back to <file>/usr/bin/editor</file>
8058 and <file>/usr/bin/pager</file> if the variable is not set.
8062 A program may also use the VISUAL environment variable to
8063 determine the user's choice of editor. If it exists, it
8064 should take precedence over EDITOR. This is in fact what
8065 <file>/usr/bin/sensible-editor</file> does.
8069 It is not required for a package to depend on
8070 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8071 package to provide such virtual packages.<footnote>
8072 The Debian base system already provides an editor and a
8078 <sect id="web-appl">
8079 <heading>Web servers and applications</heading>
8082 This section describes the locations and URLs that should
8083 be used by all web servers and web applications in the
8090 Cgi-bin executable files are installed in the
8092 <example compact="compact">
8093 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8095 and should be referred to as
8096 <example compact="compact">
8097 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8103 <p>Access to HTML documents</p>
8106 HTML documents for a package are stored in
8107 <file>/usr/share/doc/<var>package</var></file>
8108 and can be referred to as
8109 <example compact="compact">
8110 http://localhost/doc/<var>package</var>/<var>filename</var>
8115 The web server should restrict access to the document
8116 tree so that only clients on the same host can read
8117 the documents. If the web server does not support such
8118 access controls, then it should not provide access at
8119 all, or ask about providing access during installation.
8124 <p>Access to images</p>
8126 It is recommended that images for a package be stored
8127 in <tt>/usr/share/images/<var>package</var></tt> and
8128 may be referred to through an alias <tt>/images/</tt>
8131 http://localhost/images/<package>/<filename>
8138 <p>Web Document Root</p>
8141 Web Applications should try to avoid storing files in
8142 the Web Document Root. Instead they should use the
8143 /usr/share/doc/<var>package</var> directory for
8144 documents and register the Web Application via the
8145 <package>doc-base</package> package. If access to the
8146 web document root is unavoidable then use
8147 <example compact="compact">
8150 as the Document Root. This might be just a symbolic
8151 link to the location where the system administrator
8152 has put the real document root.
8155 <item><p>Providing httpd and/or httpd-cgi</p>
8157 All web servers should provide the virtual package
8158 <tt>httpd</tt>. If a web server has CGI support it should
8159 provide <tt>httpd-cgi</tt> additionally.
8162 All web applications which do not contain CGI scripts should
8163 depend on <tt>httpd</tt>, all those web applications which
8164 <tt>do</tt> contain CGI scripts, should depend on
8172 <sect id="mail-transport-agents">
8173 <heading>Mail transport, delivery and user agents</heading>
8176 Debian packages which process electronic mail, whether mail
8177 user agents (MUAs) or mail transport agents (MTAs), must
8178 ensure that they are compatible with the configuration
8179 decisions below. Failure to do this may result in lost
8180 mail, broken <tt>From:</tt> lines, and other serious brain
8185 The mail spool is <file>/var/mail</file> and the interface to
8186 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8187 the FHS). On older systems, the mail spool may be
8188 physically located in <file>/var/spool/mail</file>, but all
8189 access to the mail spool should be via the
8190 <file>/var/mail</file> symlink. The mail spool is part of the
8191 base system and not part of the MTA package.
8195 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8196 programs (such as IMAP daemons) must lock the mailbox in an
8197 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8198 be combined with dot locking. To avoid deadlocks, a program
8199 should use <tt>fcntl()</tt> first and dot locking after
8200 this, or alternatively implement the two locking methods in
8201 a non blocking way<footnote>
8202 If it is not possible to establish both locks, the
8203 system shouldn't wait for the second lock to be
8204 established, but remove the first lock, wait a (random)
8205 time, and start over locking again.
8206 </footnote>. Using the functions <tt>maillock</tt> and
8207 <tt>mailunlock</tt> provided by the
8208 <tt>liblockfile*</tt><footnote>
8209 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8210 to use these functions.
8211 </footnote> packages is the recommended way to realize this.
8215 Mailboxes are generally either mode 600 and owned by
8216 <var>user</var> or mode 660 and owned by
8217 <tt><var>user</var>:mail</tt><footnote>
8218 There are two traditional permission schemes for mail spools:
8219 mode 600 with all mail delivery done by processes running as
8220 the destination user, or mode 660 and owned by group mail with
8221 mail delivery done by a process running as a system user in
8222 group mail. Historically, Debian required mode 660 mail
8223 spools to enable the latter model, but that model has become
8224 increasingly uncommon and the principle of least privilege
8225 indicates that mail systems that use the first model should
8226 use permissions of 600. If delivery to programs is permitted,
8227 it's easier to keep the mail system secure if the delivery
8228 agent runs as the destination user. Debian Policy therefore
8229 permits either scheme.
8230 </footnote>. The local system administrator may choose a
8231 different permission scheme; packages should not make
8232 assumptions about the permission and ownership of mailboxes
8233 unless required (such as when creating a new mailbox). A MUA
8234 may remove a mailbox (unless it has nonstandard permissions) in
8235 which case the MTA or another MUA must recreate it if needed.
8239 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8240 be setgid mail to do the locking mentioned above (and
8241 must obviously avoid accessing other users' mailboxes
8242 using this privilege).</p>
8245 <file>/etc/aliases</file> is the source file for the system mail
8246 aliases (e.g., postmaster, usenet, etc.), it is the one
8247 which the sysadmin and <prgn>postinst</prgn> scripts may
8248 edit. After <file>/etc/aliases</file> is edited the program or
8249 human editing it must call <prgn>newaliases</prgn>. All MTA
8250 packages must come with a <prgn>newaliases</prgn> program,
8251 even if it does nothing, but older MTA packages did not do
8252 this so programs should not fail if <prgn>newaliases</prgn>
8253 cannot be found. Note that because of this, all MTA
8254 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8255 <tt>Replaces: mail-transport-agent</tt> control file
8260 The convention of writing <tt>forward to
8261 <var>address</var></tt> in the mailbox itself is not
8262 supported. Use a <tt>.forward</tt> file instead.</p>
8265 The <prgn>rmail</prgn> program used by UUCP
8266 for incoming mail should be <file>/usr/sbin/rmail</file>.
8267 Likewise, <prgn>rsmtp</prgn>, for receiving
8268 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8272 If your package needs to know what hostname to use on (for
8273 example) outgoing news and mail messages which are generated
8274 locally, you should use the file <file>/etc/mailname</file>. It
8275 will contain the portion after the username and <tt>@</tt>
8276 (at) sign for email addresses of users on the machine
8277 (followed by a newline).
8281 Such a package should check for the existence of this file
8282 when it is being configured. If it exists, it should be
8283 used without comment, although an MTA's configuration script
8284 may wish to prompt the user even if it finds that this file
8285 exists. If the file does not exist, the package should
8286 prompt the user for the value (preferably using
8287 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8288 as well as using it in the package's configuration. The
8289 prompt should make it clear that the name will not just be
8290 used by that package. For example, in this situation the
8291 <tt>inn</tt> package could say something like:
8292 <example compact="compact">
8293 Please enter the "mail name" of your system. This is the
8294 hostname portion of the address to be shown on outgoing
8295 news and mail messages. The default is
8296 <var>syshostname</var>, your system's host name. Mail
8297 name ["<var>syshostname</var>"]:
8299 where <var>syshostname</var> is the output of <tt>hostname
8305 <heading>News system configuration</heading>
8308 All the configuration files related to the NNTP (news)
8309 servers and clients should be located under
8310 <file>/etc/news</file>.</p>
8313 There are some configuration issues that apply to a number
8314 of news clients and server packages on the machine. These
8318 <tag><file>/etc/news/organization</file></tag>
8320 A string which should appear as the
8321 organization header for all messages posted
8322 by NNTP clients on the machine
8325 <tag><file>/etc/news/server</file></tag>
8327 Contains the FQDN of the upstream NNTP
8328 server, or localhost if the local machine is
8333 Other global files may be added as required for cross-package news
8340 <heading>Programs for the X Window System</heading>
8343 <heading>Providing X support and package priorities</heading>
8346 Programs that can be configured with support for the X
8347 Window System must be configured to do so and must declare
8348 any package dependencies necessary to satisfy their
8349 runtime requirements when using the X Window System. If
8350 such a package is of higher priority than the X packages
8351 on which it depends, it is required that either the
8352 X-specific components be split into a separate package, or
8353 that an alternative version of the package, which includes
8354 X support, be provided, or that the package's priority be
8360 <heading>Packages providing an X server</heading>
8363 Packages that provide an X server that, directly or
8364 indirectly, communicates with real input and display
8365 hardware should declare in their control data that they
8366 provide the virtual package <tt>xserver</tt>.<footnote>
8367 This implements current practice, and provides an
8368 actual policy for usage of the <tt>xserver</tt>
8369 virtual package which appears in the virtual packages
8370 list. In a nutshell, X servers that interface
8371 directly with the display and input hardware or via
8372 another subsystem (e.g., GGI) should provide
8373 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8374 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8380 <heading>Packages providing a terminal emulator</heading>
8383 Packages that provide a terminal emulator for the X Window
8384 System which meet the criteria listed below should declare
8385 in their control data that they provide the virtual
8386 package <tt>x-terminal-emulator</tt>. They should also
8387 register themselves as an alternative for
8388 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8393 To be an <tt>x-terminal-emulator</tt>, a program must:
8394 <list compact="compact">
8396 Be able to emulate a DEC VT100 terminal, or a
8397 compatible terminal.
8401 Support the command-line option <tt>-e
8402 <var>command</var></tt>, which creates a new
8403 terminal window<footnote>
8404 "New terminal window" does not necessarily mean
8405 a new top-level X window directly parented by
8406 the window manager; it could, if the terminal
8407 emulator application were so coded, be a new
8408 "view" in a multiple-document interface (MDI).
8410 and runs the specified <var>command</var>,
8411 interpreting the entirety of the rest of the command
8412 line as a command to pass straight to exec, in the
8413 manner that <tt>xterm</tt> does.
8417 Support the command-line option <tt>-T
8418 <var>title</var></tt>, which creates a new terminal
8419 window with the window title <var>title</var>.
8426 <heading>Packages providing a window manager</heading>
8429 Packages that provide a window manager should declare in
8430 their control data that they provide the virtual package
8431 <tt>x-window-manager</tt>. They should also register
8432 themselves as an alternative for
8433 <file>/usr/bin/x-window-manager</file>, with a priority
8434 calculated as follows:
8435 <list compact="compact">
8437 Start with a priority of 20.
8441 If the window manager supports the Debian menu
8442 system, add 20 points if this support is available
8443 in the package's default configuration (i.e., no
8444 configuration files belonging to the system or user
8445 have to be edited to activate the feature); if
8446 configuration files must be modified, add only 10
8452 If the window manager complies with <url
8453 id="http://www.freedesktop.org/Standards/wm-spec"
8454 name="The Window Manager Specification Project">,
8455 written by the <url id="http://www.freedesktop.org/"
8456 name="Free Desktop Group">, add 40 points.
8460 If the window manager permits the X session to be
8461 restarted using a <em>different</em> window manager
8462 (without killing the X server) in its default
8463 configuration, add 10 points; otherwise add none.
8470 <heading>Packages providing fonts</heading>
8473 Packages that provide fonts for the X Window
8475 For the purposes of Debian Policy, a "font for the X
8476 Window System" is one which is accessed via X protocol
8477 requests. Fonts for the Linux console, for PostScript
8478 renderer, or any other purpose, do not fit this
8479 definition. Any tool which makes such fonts available
8480 to the X Window System, however, must abide by this
8483 must do a number of things to ensure that they are both
8484 available without modification of the X or font server
8485 configuration, and that they do not corrupt files used by
8486 other font packages to register information about
8490 Fonts of any type supported by the X Window System
8491 must be in a separate binary package from any
8492 executables, libraries, or documentation (except
8493 that specific to the fonts shipped, such as their
8494 license information). If one or more of the fonts
8495 so packaged are necessary for proper operation of
8496 the package with which they are associated the font
8497 package may be Recommended; if the fonts merely
8498 provide an enhancement, a Suggests relationship may
8499 be used. Packages must not Depend on font
8501 This is because the X server may retrieve fonts
8502 from the local file system or over the network
8503 from an X font server; the Debian package system
8504 is empowered to deal only with the local
8510 BDF fonts must be converted to PCF fonts with the
8511 <prgn>bdftopcf</prgn> utility (available in the
8512 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8513 placed in a directory that corresponds to their
8515 <list compact="compact">
8517 100 dpi fonts must be placed in
8518 <file>/usr/share/fonts/X11/100dpi/</file>.
8522 75 dpi fonts must be placed in
8523 <file>/usr/share/fonts/X11/75dpi/</file>.
8527 Character-cell fonts, cursor fonts, and other
8528 low-resolution fonts must be placed in
8529 <file>/usr/share/fonts/X11/misc/</file>.
8535 Type 1 fonts must be placed in
8536 <file>/usr/share/fonts/X11/Type1/</file>. If font
8537 metric files are available, they must be placed here
8542 Subdirectories of <file>/usr/share/fonts/X11/</file>
8543 other than those listed above must be neither
8544 created nor used. (The <file>PEX</file>, <file>CID</file>,
8545 <file>Speedo</file>, and <file>cyrillic</file> directories
8546 are excepted for historical reasons, but installation of
8547 files into these directories remains discouraged.)
8551 Font packages may, instead of placing files directly
8552 in the X font directories listed above, provide
8553 symbolic links in that font directory pointing to
8554 the files' actual location in the filesystem. Such
8555 a location must comply with the FHS.
8559 Font packages should not contain both 75dpi and
8560 100dpi versions of a font. If both are available,
8561 they should be provided in separate binary packages
8562 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8563 the names of the packages containing the
8564 corresponding fonts.
8568 Fonts destined for the <file>misc</file> subdirectory
8569 should not be included in the same package as 75dpi
8570 or 100dpi fonts; instead, they should be provided in
8571 a separate package with <tt>-misc</tt> appended to
8576 Font packages must not provide the files
8577 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8578 <file>fonts.scale</file> in a font directory:
8581 <file>fonts.dir</file> files must not be provided at all.
8585 <file>fonts.alias</file> and <file>fonts.scale</file>
8586 files, if needed, should be provided in the
8588 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8589 where <var>fontdir</var> is the name of the
8591 <file>/usr/share/fonts/X11/</file> where the
8592 package's corresponding fonts are stored
8593 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8594 <var>package</var> is the name of the package
8595 that provides these fonts, and
8596 <var>extension</var> is either <tt>scale</tt>
8597 or <tt>alias</tt>, whichever corresponds to
8604 Font packages must declare a dependency on
8605 <tt>xfonts-utils</tt> in their control
8610 Font packages that provide one or more
8611 <file>fonts.scale</file> files as described above must
8612 invoke <prgn>update-fonts-scale</prgn> on each
8613 directory into which they installed fonts
8614 <em>before</em> invoking
8615 <prgn>update-fonts-dir</prgn> on that directory.
8616 This invocation must occur in both the
8617 <prgn>postinst</prgn> (for all arguments) and
8618 <prgn>postrm</prgn> (for all arguments except
8619 <tt>upgrade</tt>) scripts.
8623 Font packages that provide one or more
8624 <file>fonts.alias</file> files as described above must
8625 invoke <prgn>update-fonts-alias</prgn> on each
8626 directory into which they installed fonts. This
8627 invocation must occur in both the
8628 <prgn>postinst</prgn> (for all arguments) and
8629 <prgn>postrm</prgn> (for all arguments except
8630 <tt>upgrade</tt>) scripts.
8634 Font packages must invoke
8635 <prgn>update-fonts-dir</prgn> on each directory into
8636 which they installed fonts. This invocation must
8637 occur in both the <prgn>postinst</prgn> (for all
8638 arguments) and <prgn>postrm</prgn> (for all
8639 arguments except <tt>upgrade</tt>) scripts.
8643 Font packages must not provide alias names for the
8644 fonts they include which collide with alias names
8645 already in use by fonts already packaged.
8649 Font packages must not provide fonts with the same
8650 XLFD registry name as another font already packaged.
8656 <sect1 id="appdefaults">
8657 <heading>Application defaults files</heading>
8660 Application defaults files must be installed in the
8661 directory <file>/etc/X11/app-defaults/</file> (use of a
8662 localized subdirectory of <file>/etc/X11/</file> as described
8663 in the <em>X Toolkit Intrinsics - C Language
8664 Interface</em> manual is also permitted). They must be
8665 registered as <tt>conffile</tt>s or handled as
8666 configuration files.
8670 Customization of programs' X resources may also be
8671 supported with the provision of a file with the same name
8672 as that of the package placed in the
8673 <file>/etc/X11/Xresources/</file> directory, which must
8674 registered as a <tt>conffile</tt> or handled as a
8675 configuration file.<footnote>
8676 Note that this mechanism is not the same as using
8677 app-defaults; app-defaults are tied to the client
8678 binary on the local file system, whereas X resources
8679 are stored in the X server and affect all connecting
8686 <heading>Installation directory issues</heading>
8689 Historically, packages using the X Window System used a
8690 separate set of installation directories from other packages.
8691 This practice has been discontinued and packages using the X
8692 Window System should now generally be installed in the same
8693 directories as any other package. Specifically, packages must
8694 not install files under the <file>/usr/X11R6/</file> directory
8695 and the <file>/usr/X11R6/</file> directory hierarchy should be
8696 regarded as obsolete.
8700 Include files previously installed under
8701 <file>/usr/X11R6/include/X11/</file> should be installed into
8702 <file>/usr/include/X11/</file>. For files previously
8703 installed into subdirectories of
8704 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8705 determine if subdirectories of <file>/usr/lib/</file> and
8706 <file>/usr/share/</file> can be used. If not, a subdirectory
8707 of <file>/usr/lib/X11/</file> should be used.
8711 Configuration files for window, display, or session managers
8712 or other applications that are tightly integrated with the X
8713 Window System may be placed in a subdirectory
8714 of <file>/etc/X11/</file> corresponding to the package name.
8715 Other X Window System applications should use
8716 the <file>/etc/</file> directory unless otherwise mandated by
8717 policy (such as for <ref id="appdefaults">).
8722 <heading>The OSF/Motif and OpenMotif libraries</heading>
8725 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8726 OpenMotif libraries</em><footnote>
8727 OSF/Motif and OpenMotif are collectively referred to as
8728 "Motif" in this policy document.
8730 should be compiled against and tested with LessTif (a free
8731 re-implementation of Motif) instead. If the maintainer
8732 judges that the program or programs do not work
8733 sufficiently well with LessTif to be distributed and
8734 supported, but do so when compiled against Motif, then two
8735 versions of the package should be created; one linked
8736 statically against Motif and with <tt>-smotif</tt>
8737 appended to the package name, and one linked dynamically
8738 against Motif and with <tt>-dmotif</tt> appended to the
8743 Both Motif-linked versions are dependent
8744 upon non-DFSG-compliant software and thus cannot be
8745 uploaded to the <em>main</em> distribution; if the
8746 software is itself DFSG-compliant it may be uploaded to
8747 the <em>contrib</em> distribution. While known existing
8748 versions of Motif permit unlimited redistribution of
8749 binaries linked against the library (whether statically or
8750 dynamically), it is the package maintainer's
8751 responsibility to determine whether this is permitted by
8752 the license of the copy of Motif in their possession.
8758 <heading>Perl programs and modules</heading>
8761 Perl programs and modules should follow the current Perl policy.
8765 The Perl policy can be found in the <tt>perl-policy</tt>
8766 files in the <tt>debian-policy</tt> package.
8767 It is also available from the Debian web mirrors at
8768 <tt><url name="/doc/packaging-manuals/perl-policy/"
8769 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8774 <heading>Emacs lisp programs</heading>
8777 Please refer to the "Debian Emacs Policy" for details of how to
8778 package emacs lisp programs.
8782 The Emacs policy is available in
8783 <file>debian-emacs-policy.gz</file> of the
8784 <package>emacsen-common</package> package.
8785 It is also available from the Debian web mirrors at
8786 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8787 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8792 <heading>Games</heading>
8795 The permissions on <file>/var/games</file> are mode 755, owner
8796 <tt>root</tt> and group <tt>root</tt>.
8800 Each game decides on its own security policy.</p>
8803 Games which require protected, privileged access to
8804 high-score files, saved games, etc., may be made
8805 set-<em>group</em>-id (mode 2755) and owned by
8806 <tt>root:games</tt>, and use files and directories with
8807 appropriate permissions (770 <tt>root:games</tt>, for
8808 example). They must not be made
8809 set-<em>user</em>-id, as this causes security problems. (If
8810 an attacker can subvert any set-user-id game they can
8811 overwrite the executable of any other, causing other players
8812 of these games to run a Trojan horse program. With a
8813 set-group-id game the attacker only gets access to less
8814 important game data, and if they can get at the other
8815 players' accounts at all it will take considerably more
8819 Some packages, for example some fortune cookie programs, are
8820 configured by the upstream authors to install with their
8821 data files or other static information made unreadable so
8822 that they can only be accessed through set-id programs
8823 provided. You should not do this in a Debian package: anyone can
8824 download the <file>.deb</file> file and read the data from it,
8825 so there is no point making the files unreadable. Not
8826 making the files unreadable also means that you don't have
8827 to make so many programs set-id, which reduces the risk of a
8831 As described in the FHS, binaries of games should be
8832 installed in the directory <file>/usr/games</file>. This also
8833 applies to games that use the X Window System. Manual pages
8834 for games (X and non-X games) should be installed in
8835 <file>/usr/share/man/man6</file>.</p>
8841 <heading>Documentation</heading>
8844 <heading>Manual pages</heading>
8847 You should install manual pages in <prgn>nroff</prgn> source
8848 form, in appropriate places under <file>/usr/share/man</file>.
8849 You should only use sections 1 to 9 (see the FHS for more
8850 details). You must not install a pre-formatted "cat page".
8854 Each program, utility, and function should have an
8855 associated manual page included in the same package. It is
8856 suggested that all configuration files also have a manual
8857 page included as well. Manual pages for protocols and other
8858 auxiliary things are optional.
8862 If no manual page is available, this is considered as a bug
8863 and should be reported to the Debian Bug Tracking System (the
8864 maintainer of the package is allowed to write this bug report
8865 themselves, if they so desire). Do not close the bug report
8866 until a proper man page is available.<footnote>
8867 It is not very hard to write a man page. See the
8868 <url id="http://www.schweikhardt.net/man_page_howto.html"
8869 name="Man-Page-HOWTO">,
8870 <manref name="man" section="7">, the examples
8871 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8872 the helper programs <prgn>help2man</prgn>, or the
8873 directory <file>/usr/share/doc/man-db/examples</file>.
8878 You may forward a complaint about a missing man page to the
8879 upstream authors, and mark the bug as forwarded in the
8880 Debian bug tracking system. Even though the GNU Project do
8881 not in general consider the lack of a man page to be a bug,
8882 we do; if they tell you that they don't consider it a bug
8883 you should leave the bug in our bug tracking system open
8888 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8892 If one man page needs to be accessible via several names it
8893 is better to use a symbolic link than the <file>.so</file>
8894 feature, but there is no need to fiddle with the relevant
8895 parts of the upstream source to change from <file>.so</file> to
8896 symlinks: don't do it unless it's easy. You should not
8897 create hard links in the manual page directories, nor put
8898 absolute filenames in <file>.so</file> directives. The filename
8899 in a <file>.so</file> in a man page should be relative to the
8900 base of the man page tree (usually
8901 <file>/usr/share/man</file>). If you do not create any links
8902 (whether symlinks, hard links, or <tt>.so</tt> directives)
8903 in the file system to the alternate names of the man page,
8904 then you should not rely on <prgn>man</prgn> finding your
8905 man page under those names based solely on the information in
8906 the man page's header.<footnote>
8907 Supporting this in <prgn>man</prgn> often requires
8908 unreasonable processing time to find a manual page or to
8909 report that none exists, and moves knowledge into man's
8910 database that would be better left in the file system.
8911 This support is therefore deprecated and will cease to
8912 be present in the future.
8917 Manual pages in locale-specific subdirectories of
8918 <file>/usr/share/man</file> should use either UTF-8 or the usual
8919 legacy encoding for that language (normally the one corresponding
8920 to the shortest relevant locale name in
8921 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8922 <file>/usr/share/man/fr</file> should use either UTF-8 or
8923 ISO-8859-1.<footnote>
8924 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8925 use. In future, all manual pages will be required to use
8931 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8932 included in the subdirectory name unless it indicates a
8933 significant difference in the language, as this excludes
8934 speakers of the language in other countries.<footnote>
8935 At the time of writing, Chinese and Portuguese are the main
8936 languages with such differences, so <file>pt_BR</file>,
8937 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8942 If a localized version of a manual page is provided, it should
8943 either be up-to-date or it should be obvious to the reader that
8944 it is outdated and the original manual page should be used
8945 instead. This can be done either by a note at the beginning of
8946 the manual page or by showing the missing or changed portions in
8947 the original language instead of the target language.
8952 <heading>Info documents</heading>
8955 Info documents should be installed in <file>/usr/share/info</file>.
8956 They should be compressed with <tt>gzip -9</tt>.
8960 The <prgn>install-info</prgn> program maintains a directory of
8961 installed info documents in <file>/usr/share/info/dir</file> for
8962 the use of info readers.<footnote>
8963 It was previously necessary for packages installing info
8964 documents to run <prgn>install-info</prgn> from maintainer
8965 scripts. This is no longer necessary. The installation
8966 system now uses dpkg triggers.
8968 This file must not be included in packages. Packages containing
8969 info documents should depend on <tt>dpkg (>= 1.15.4) |
8970 install-info</tt> to ensure that the directory file is properly
8971 rebuilt during partial upgrades from Debian 5.0 (lenny) and
8976 Info documents should contain section and directory entry
8977 information in the document for the use
8978 of <prgn>install-info</prgn>. The section should be specified
8979 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8980 space and the section of this info page. The directory entry or
8981 entries should be included between
8982 a <tt>START-INFO-DIR-ENTRY</tt> line and
8983 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8985 INFO-DIR-SECTION Individual utilities
8986 START-INFO-DIR-ENTRY
8987 * example: (example). An example info directory entry.
8990 To determine which section to use, you should look
8991 at <file>/usr/share/info/dir</file> on your system and choose
8992 the most relevant (or create a new section if none of the
8993 current sections are relevant).<footnote>
8994 Normally, info documents are generated from Texinfo source.
8995 To include this information in the generated info document, if
8996 it is absent, add commands like:
8998 @dircategory Individual utilities
9000 * example: (example). An example info directory entry.
9003 to the Texinfo source of the document and ensure that the info
9004 documents are rebuilt from source during the package build.
9010 <heading>Additional documentation</heading>
9013 Any additional documentation that comes with the package may
9014 be installed at the discretion of the package maintainer.
9015 Plain text documentation should be installed in the directory
9016 <file>/usr/share/doc/<var>package</var></file>, where
9017 <var>package</var> is the name of the package, and
9018 compressed with <tt>gzip -9</tt> unless it is small.
9022 If a package comes with large amounts of documentation which
9023 many users of the package will not require you should create
9024 a separate binary package to contain it, so that it does not
9025 take up disk space on the machines of users who do not need
9026 or want it installed.</p>
9029 It is often a good idea to put text information files
9030 (<file>README</file>s, changelogs, and so forth) that come with
9031 the source package in <file>/usr/share/doc/<var>package</var></file>
9032 in the binary package. However, you don't need to install
9033 the instructions for building and installing the package, of
9037 Packages must not require the existence of any files in
9038 <file>/usr/share/doc/</file> in order to function
9040 The system administrator should be able to
9041 delete files in <file>/usr/share/doc/</file> without causing
9042 any programs to break.
9044 Any files that are referenced by programs but are also
9045 useful as stand alone documentation should be installed under
9046 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9047 <file>/usr/share/doc/<var>package</var></file>.
9051 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9052 link to another directory in <file>/usr/share/doc</file> only if
9053 the two packages both come from the same source and the
9054 first package Depends on the second.<footnote>
9056 Please note that this does not override the section on
9057 changelog files below, so the file
9058 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
9059 must refer to the changelog for the current version of
9060 <var>package</var> in question. In practice, this means
9061 that the sources of the target and the destination of the
9062 symlink must be the same (same source package and
9069 Former Debian releases placed all additional documentation
9070 in <file>/usr/doc/<var>package</var></file>. This has been
9071 changed to <file>/usr/share/doc/<var>package</var></file>,
9072 and packages must not put documentation in the directory
9073 <file>/usr/doc/<var>package</var></file>. <footnote>
9074 At this phase of the transition, we no longer require a
9075 symbolic link in <file>/usr/doc/</file>. At a later point,
9076 policy shall change to make the symbolic links a bug.
9082 <heading>Preferred documentation formats</heading>
9085 The unification of Debian documentation is being carried out
9089 If your package comes with extensive documentation in a
9090 markup format that can be converted to various other formats
9091 you should if possible ship HTML versions in a binary
9092 package, in the directory
9093 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9094 its subdirectories.<footnote>
9095 The rationale: The important thing here is that HTML
9096 docs should be available in <em>some</em> package, not
9097 necessarily in the main binary package.
9102 Other formats such as PostScript may be provided at the
9103 package maintainer's discretion.
9107 <sect id="copyrightfile">
9108 <heading>Copyright information</heading>
9111 Every package must be accompanied by a verbatim copy of its
9112 copyright and distribution license in the file
9113 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9114 file must neither be compressed nor be a symbolic link.
9118 In addition, the copyright file must say where the upstream
9119 sources (if any) were obtained. It should name the original
9120 authors of the package and the Debian maintainer(s) who were
9121 involved with its creation.
9125 Packages in the <em>contrib</em> or <em>non-free</em> archive
9126 areas should state in the copyright file that the package is not
9127 part of the Debian GNU/Linux distribution and briefly explain
9132 A copy of the file which will be installed in
9133 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9134 be in <file>debian/copyright</file> in the source package.
9138 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9139 link to another directory in <file>/usr/share/doc</file> only if
9140 the two packages both come from the same source and the
9141 first package Depends on the second. These rules are
9142 important because copyrights must be extractable by
9147 Packages distributed under the UCB BSD license, the Apache
9148 license (version 2.0), the Artistic license, the GNU GPL
9149 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9150 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9151 files under <file>/usr/share/common-licenses</file>,<footnote>
9154 <file>/usr/share/common-licenses/BSD</file>,
9155 <file>/usr/share/common-licenses/Apache-2.0</file>,
9156 <file>/usr/share/common-licenses/Artistic</file>,
9157 <file>/usr/share/common-licenses/GPL-2</file>,
9158 <file>/usr/share/common-licenses/GPL-3</file>,
9159 <file>/usr/share/common-licenses/LGPL-2</file>,
9160 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9161 <file>/usr/share/common-licenses/LGPL-3</file>,
9162 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9163 <file>/usr/share/common-licenses/GFDL-1.3</file>
9166 </footnote> rather than quoting them in the copyright
9171 You should not use the copyright file as a general <file>README</file>
9172 file. If your package has such a file it should be
9173 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9174 <file>README.Debian</file> or some other appropriate place.</p>
9178 <heading>Examples</heading>
9181 Any examples (configurations, source files, whatever),
9182 should be installed in a directory
9183 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9184 files should not be referenced by any program: they're there
9185 for the benefit of the system administrator and users as
9186 documentation only. Architecture-specific example files
9187 should be installed in a directory
9188 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9190 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9191 latter directory itself may be a symbolic link to the
9196 If the purpose of a package is to provide examples, then the
9197 example files may be installed into
9198 <file>/usr/share/doc/<var>package</var></file>.
9202 <sect id="changelogs">
9203 <heading>Changelog files</heading>
9206 Packages that are not Debian-native must contain a
9207 compressed copy of the <file>debian/changelog</file> file from
9208 the Debian source tree in
9209 <file>/usr/share/doc/<var>package</var></file> with the name
9210 <file>changelog.Debian.gz</file>.
9214 If an upstream changelog is available, it should be accessible as
9215 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9216 plain text. If the upstream changelog is distributed in
9217 HTML, it should be made available in that form as
9218 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9219 and a plain text <file>changelog.gz</file> should be generated
9220 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9221 the upstream changelog files do not already conform to this
9222 naming convention, then this may be achieved either by
9223 renaming the files, or by adding a symbolic link, at the
9224 maintainer's discretion.<footnote>
9225 Rationale: People should not have to look in places for
9226 upstream changelogs merely because they are given
9227 different names or are distributed in HTML format.
9232 All of these files should be installed compressed using
9233 <tt>gzip -9</tt>, as they will become large with time even
9234 if they start out small.
9238 If the package has only one changelog which is used both as
9239 the Debian changelog and the upstream one because there is
9240 no separate upstream maintainer then that changelog should
9241 usually be installed as
9242 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9243 there is a separate upstream maintainer, but no upstream
9244 changelog, then the Debian changelog should still be called
9245 <file>changelog.Debian.gz</file>.
9249 For details about the format and contents of the Debian
9250 changelog file, please see <ref id="dpkgchangelog">.
9255 <appendix id="pkg-scope">
9256 <heading>Introduction and scope of these appendices</heading>
9259 These appendices are taken essentially verbatim from the
9260 now-deprecated Packaging Manual, version 3.2.1.0. They are
9261 the chapters which are likely to be of use to package
9262 maintainers and which have not already been included in the
9263 policy document itself. Most of these sections are very likely
9264 not relevant to policy; they should be treated as
9265 documentation for the packaging system. Please note that these
9266 appendices are included for convenience, and for historical
9267 reasons: they used to be part of policy package, and they have
9268 not yet been incorporated into dpkg documentation. However,
9269 they still have value, and hence they are presented here.
9273 They have not yet been checked to ensure that they are
9274 compatible with the contents of policy, and if there are any
9275 contradictions, the version in the main policy document takes
9276 precedence. The remaining chapters of the old Packaging
9277 Manual have also not been read in detail to ensure that there
9278 are not parts which have been left out. Both of these will be
9283 Certain parts of the Packaging manual were integrated into the
9284 Policy Manual proper, and removed from the appendices. Links
9285 have been placed from the old locations to the new ones.
9289 <prgn>dpkg</prgn> is a suite of programs for creating binary
9290 package files and installing and removing them on Unix
9292 <prgn>dpkg</prgn> is targeted primarily at Debian
9293 GNU/Linux, but may work on or be ported to other
9299 The binary packages are designed for the management of
9300 installed executable programs (usually compiled binaries) and
9301 their associated data, though source code examples and
9302 documentation are provided as part of some packages.</p>
9305 This manual describes the technical aspects of creating Debian
9306 binary packages (<file>.deb</file> files). It documents the
9307 behavior of the package management programs
9308 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9309 they interact with packages.</p>
9312 It also documents the interaction between
9313 <prgn>dselect</prgn>'s core and the access method scripts it
9314 uses to actually install the selected packages, and describes
9315 how to create a new access method.</p>
9318 This manual does not go into detail about the options and
9319 usage of the package building and installation tools. It
9320 should therefore be read in conjunction with those programs'
9325 The utility programs which are provided with <prgn>dpkg</prgn>
9326 for managing various system configuration and similar issues,
9327 such as <prgn>update-rc.d</prgn> and
9328 <prgn>install-info</prgn>, are not described in detail here -
9329 please see their man pages.
9333 It is assumed that the reader is reasonably familiar with the
9334 <prgn>dpkg</prgn> System Administrators' manual.
9335 Unfortunately this manual does not yet exist.
9339 The Debian version of the FSF's GNU hello program is provided
9340 as an example for people wishing to create Debian
9341 packages. The Debian <prgn>debmake</prgn> package is
9342 recommended as a very helpful tool in creating and maintaining
9343 Debian packages. However, while the tools and examples are
9344 helpful, they do not replace the need to read and follow the
9345 Policy and Programmer's Manual.</p>
9348 <appendix id="pkg-binarypkg">
9349 <heading>Binary packages (from old Packaging Manual)</heading>
9352 The binary package has two main sections. The first part
9353 consists of various control information files and scripts used
9354 by <prgn>dpkg</prgn> when installing and removing. See <ref
9355 id="pkg-controlarea">.
9359 The second part is an archive containing the files and
9360 directories to be installed.
9364 In the future binary packages may also contain other
9365 components, such as checksums and digital signatures. The
9366 format for the archive is described in full in the
9367 <file>deb(5)</file> man page.
9371 <sect id="pkg-bincreating"><heading>Creating package files -
9372 <prgn>dpkg-deb</prgn>
9376 All manipulation of binary package files is done by
9377 <prgn>dpkg-deb</prgn>; it's the only program that has
9378 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9379 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9380 will spot that the options requested are appropriate to
9381 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9386 In order to create a binary package you must make a
9387 directory tree which contains all the files and directories
9388 you want to have in the file system data part of the package.
9389 In Debian-format source packages this directory is usually
9390 <file>debian/tmp</file>, relative to the top of the package's
9395 They should have the locations (relative to the root of the
9396 directory tree you're constructing) ownerships and
9397 permissions which you want them to have on the system when
9402 With current versions of <prgn>dpkg</prgn> the uid/username
9403 and gid/groupname mappings for the users and groups being
9404 used should be the same on the system where the package is
9405 built and the one where it is installed.
9409 You need to add one special directory to the root of the
9410 miniature file system tree you're creating:
9411 <prgn>DEBIAN</prgn>. It should contain the control
9412 information files, notably the binary package control file
9413 (see <ref id="pkg-controlfile">).
9417 The <prgn>DEBIAN</prgn> directory will not appear in the
9418 file system archive of the package, and so won't be installed
9419 by <prgn>dpkg</prgn> when the package is installed.
9423 When you've prepared the package, you should invoke:
9425 dpkg --build <var>directory</var>
9430 This will build the package in
9431 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9432 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9433 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9438 See the man page <manref name="dpkg-deb" section="8"> for details of how
9439 to examine the contents of this newly-created file. You may find the
9440 output of following commands enlightening:
9442 dpkg-deb --info <var>filename</var>.deb
9443 dpkg-deb --contents <var>filename</var>.deb
9444 dpkg --contents <var>filename</var>.deb
9446 To view the copyright file for a package you could use this command:
9448 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9453 <sect id="pkg-controlarea">
9454 <heading>Package control information files</heading>
9457 The control information portion of a binary package is a
9458 collection of files with names known to <prgn>dpkg</prgn>.
9459 It will treat the contents of these files specially - some
9460 of them contain information used by <prgn>dpkg</prgn> when
9461 installing or removing the package; others are scripts which
9462 the package maintainer wants <prgn>dpkg</prgn> to run.
9466 It is possible to put other files in the package control
9467 area, but this is not generally a good idea (though they
9468 will largely be ignored).
9472 Here is a brief list of the control info files supported by
9473 <prgn>dpkg</prgn> and a summary of what they're used for.
9478 <tag><tt>control</tt>
9481 This is the key description file used by
9482 <prgn>dpkg</prgn>. It specifies the package's name
9483 and version, gives its description for the user,
9484 states its relationships with other packages, and so
9485 forth. See <ref id="sourcecontrolfiles"> and
9486 <ref id="binarycontrolfiles">.
9490 It is usually generated automatically from information
9491 in the source package by the
9492 <prgn>dpkg-gencontrol</prgn> program, and with
9493 assistance from <prgn>dpkg-shlibdeps</prgn>.
9494 See <ref id="pkg-sourcetools">.
9498 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9503 These are executable files (usually scripts) which
9504 <prgn>dpkg</prgn> runs during installation, upgrade
9505 and removal of packages. They allow the package to
9506 deal with matters which are particular to that package
9507 or require more complicated processing than that
9508 provided by <prgn>dpkg</prgn>. Details of when and
9509 how they are called are in <ref id="maintainerscripts">.
9513 It is very important to make these scripts idempotent.
9514 See <ref id="idempotency">.
9518 The maintainer scripts are guaranteed to run with a
9519 controlling terminal and can interact with the user.
9520 See <ref id="controllingterminal">.
9524 <tag><tt>conffiles</tt>
9527 This file contains a list of configuration files which
9528 are to be handled automatically by <prgn>dpkg</prgn>
9529 (see <ref id="pkg-conffiles">). Note that not necessarily
9530 every configuration file should be listed here.
9533 <tag><tt>shlibs</tt>
9536 This file contains a list of the shared libraries
9537 supplied by the package, with dependency details for
9538 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9539 when it determines what dependencies are required in a
9540 package control file. The <tt>shlibs</tt> file format
9541 is described on <ref id="shlibs">.
9546 <sect id="pkg-controlfile">
9547 <heading>The main control information file: <tt>control</tt></heading>
9550 The most important control information file used by
9551 <prgn>dpkg</prgn> when it installs a package is
9552 <tt>control</tt>. It contains all the package's "vital
9557 The binary package control files of packages built from
9558 Debian sources are made by a special tool,
9559 <prgn>dpkg-gencontrol</prgn>, which reads
9560 <file>debian/control</file> and <file>debian/changelog</file> to
9561 find the information it needs. See <ref id="pkg-sourcepkg"> for
9566 The fields in binary package control files are listed in
9567 <ref id="binarycontrolfiles">.
9571 A description of the syntax of control files and the purpose
9572 of the fields is available in <ref id="controlfields">.
9577 <heading>Time Stamps</heading>
9580 See <ref id="timestamps">.
9585 <appendix id="pkg-sourcepkg">
9586 <heading>Source packages (from old Packaging Manual) </heading>
9589 The Debian binary packages in the distribution are generated
9590 from Debian sources, which are in a special format to assist
9591 the easy and automatic building of binaries.
9594 <sect id="pkg-sourcetools">
9595 <heading>Tools for processing source packages</heading>
9598 Various tools are provided for manipulating source packages;
9599 they pack and unpack sources and help build of binary
9600 packages and help manage the distribution of new versions.
9604 They are introduced and typical uses described here; see
9605 <manref name="dpkg-source" section="1"> for full
9606 documentation about their arguments and operation.
9610 For examples of how to construct a Debian source package,
9611 and how to use those utilities that are used by Debian
9612 source packages, please see the <prgn>hello</prgn> example
9616 <sect1 id="pkg-dpkg-source">
9618 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9623 This program is frequently used by hand, and is also
9624 called from package-independent automated building scripts
9625 such as <prgn>dpkg-buildpackage</prgn>.
9629 To unpack a package it is typically invoked with
9631 dpkg-source -x <var>.../path/to/filename</var>.dsc
9636 with the <file><var>filename</var>.tar.gz</file> and
9637 <file><var>filename</var>.diff.gz</file> (if applicable) in
9638 the same directory. It unpacks into
9639 <file><var>package</var>-<var>version</var></file>, and if
9641 <file><var>package</var>-<var>version</var>.orig</file>, in
9642 the current directory.
9646 To create a packed source archive it is typically invoked:
9648 dpkg-source -b <var>package</var>-<var>version</var>
9653 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9654 <file>.diff.gz</file> (if appropriate) in the current
9655 directory. <prgn>dpkg-source</prgn> does not clean the
9656 source tree first - this must be done separately if it is
9661 See also <ref id="pkg-sourcearchives">.</p>
9665 <sect1 id="pkg-dpkg-buildpackage">
9667 <prgn>dpkg-buildpackage</prgn> - overall package-building
9672 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9673 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9674 targets <tt>clean</tt>, <tt>build</tt> and
9675 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9676 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9677 source and binary package upload.
9681 It is usually invoked by hand from the top level of the
9682 built or unbuilt source directory. It may be invoked with
9683 no arguments; useful arguments include:
9684 <taglist compact="compact">
9685 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9688 Do not sign the <tt>.changes</tt> file or the
9689 source package <tt>.dsc</tt> file, respectively.</p>
9691 <tag><tt>-p<var>sign-command</var></tt></tag>
9694 Invoke <var>sign-command</var> instead of finding
9695 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9696 <var>sign-command</var> must behave just like
9697 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9699 <tag><tt>-r<var>root-command</var></tt></tag>
9702 When root privilege is required, invoke the command
9703 <var>root-command</var>. <var>root-command</var>
9704 should invoke its first argument as a command, from
9705 the <prgn>PATH</prgn> if necessary, and pass its
9706 second and subsequent arguments to the command it
9707 calls. If no <var>root-command</var> is supplied
9708 then <var>dpkg-buildpackage</var> will take no
9709 special action to gain root privilege, so that for
9710 most packages it will have to be invoked as root to
9713 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9716 Two types of binary-only build and upload - see
9717 <manref name="dpkg-source" section="1">.
9724 <sect1 id="pkg-dpkg-gencontrol">
9726 <prgn>dpkg-gencontrol</prgn> - generates binary package
9731 This program is usually called from <file>debian/rules</file>
9732 (see <ref id="pkg-sourcetree">) in the top level of the source
9737 This is usually done just before the files and directories in the
9738 temporary directory tree where the package is being built have their
9739 permissions and ownerships set and the package is constructed using
9740 <prgn>dpkg-deb/</prgn>
9742 This is so that the control file which is produced has
9743 the right permissions
9748 <prgn>dpkg-gencontrol</prgn> must be called after all the
9749 files which are to go into the package have been placed in
9750 the temporary build directory, so that its calculation of
9751 the installed size of a package is correct.
9755 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9756 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9757 variable substitutions created by
9758 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9763 For a package which generates only one binary package, and
9764 which builds it in <file>debian/tmp</file> relative to the top
9765 of the source package, it is usually sufficient to call
9766 <prgn>dpkg-gencontrol</prgn>.
9770 Sources which build several binaries will typically need
9773 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9774 </example> The <tt>-P</tt> tells
9775 <prgn>dpkg-gencontrol</prgn> that the package is being
9776 built in a non-default directory, and the <tt>-p</tt>
9777 tells it which package's control file should be generated.
9781 <prgn>dpkg-gencontrol</prgn> also adds information to the
9782 list of files in <file>debian/files</file>, for the benefit of
9783 (for example) a future invocation of
9784 <prgn>dpkg-genchanges</prgn>.</p>
9787 <sect1 id="pkg-dpkg-shlibdeps">
9789 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9794 This program is usually called from <file>debian/rules</file>
9795 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9796 id="pkg-sourcetree">), in the top level of the source tree.
9800 Its arguments are executables and shared libraries
9803 They may be specified either in the locations in the
9804 source tree where they are created or in the locations
9805 in the temporary build tree where they are installed
9806 prior to binary package creation.
9808 </footnote> for which shared library dependencies should
9809 be included in the binary package's control file.
9813 If some of the found shared libraries should only
9814 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9815 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9816 by using the <tt>-d<var>dependency-field</var></tt> option
9817 before those executable(s). (Each <tt>-d</tt> option
9818 takes effect until the next <tt>-d</tt>.)
9822 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9823 output control file to be modified. Instead by default it
9824 adds to the <file>debian/substvars</file> file variable
9825 settings like <tt>shlibs:Depends</tt>. These variable
9826 settings must be referenced in dependency fields in the
9827 appropriate per-binary-package sections of the source
9832 For example, a package that generates an essential part
9833 which requires dependencies, and optional parts that
9834 which only require a recommendation, would separate those
9835 two sets of dependencies into two different fields.<footnote>
9836 At the time of writing, an example for this was the
9837 <package/xmms/ package, with Depends used for the xmms
9838 executable, Recommends for the plug-ins and Suggests for
9839 even more optional features provided by unzip.
9841 It can say in its <file>debian/rules</file>:
9843 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9844 -dRecommends <var>optionalpart anotheroptionalpart</var>
9846 and then in its main control file <file>debian/control</file>:
9849 Depends: ${shlibs:Depends}
9850 Recommends: ${shlibs:Recommends}
9856 Sources which produce several binary packages with
9857 different shared library dependency requirements can use
9858 the <tt>-p<var>varnameprefix</var></tt> option to override
9859 the default <tt>shlibs:</tt> prefix (one invocation of
9860 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9861 They can thus produce several sets of dependency
9862 variables, each of the form
9863 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9864 which can be referred to in the appropriate parts of the
9865 binary package control files.
9870 <sect1 id="pkg-dpkg-distaddfile">
9872 <prgn>dpkg-distaddfile</prgn> - adds a file to
9873 <file>debian/files</file>
9877 Some packages' uploads need to include files other than
9878 the source and binary package files.
9882 <prgn>dpkg-distaddfile</prgn> adds a file to the
9883 <file>debian/files</file> file so that it will be included in
9884 the <file>.changes</file> file when
9885 <prgn>dpkg-genchanges</prgn> is run.
9889 It is usually invoked from the <tt>binary</tt> target of
9890 <file>debian/rules</file>:
9892 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9894 The <var>filename</var> is relative to the directory where
9895 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9896 is usually the directory above the top level of the source
9897 tree. The <file>debian/rules</file> target should put the
9898 file there just before or just after calling
9899 <prgn>dpkg-distaddfile</prgn>.
9903 The <var>section</var> and <var>priority</var> are passed
9904 unchanged into the resulting <file>.changes</file> file.
9909 <sect1 id="pkg-dpkg-genchanges">
9911 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9916 This program is usually called by package-independent
9917 automatic building scripts such as
9918 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9923 It is usually called in the top level of a built source
9924 tree, and when invoked with no arguments will print out a
9925 straightforward <file>.changes</file> file based on the
9926 information in the source package's changelog and control
9927 file and the binary and source packages which should have
9933 <sect1 id="pkg-dpkg-parsechangelog">
9935 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9936 representation of a changelog
9940 This program is used internally by
9941 <prgn>dpkg-source</prgn> et al. It may also occasionally
9942 be useful in <file>debian/rules</file> and elsewhere. It
9943 parses a changelog, <file>debian/changelog</file> by default,
9944 and prints a control-file format representation of the
9945 information in it to standard output.
9949 <sect1 id="pkg-dpkg-architecture">
9951 <prgn>dpkg-architecture</prgn> - information about the build and
9956 This program can be used manually, but is also invoked by
9957 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9958 environment or make variables which specify the build and host
9959 architecture for the package building process.
9964 <sect id="pkg-sourcetree">
9965 <heading>The Debianised source tree</heading>
9968 The source archive scheme described later is intended to
9969 allow a Debianised source tree with some associated control
9970 information to be reproduced and transported easily. The
9971 Debianised source tree is a version of the original program
9972 with certain files added for the benefit of the
9973 Debianisation process, and with any other changes required
9974 made to the rest of the source code and installation
9979 The extra files created for Debian are in the subdirectory
9980 <file>debian</file> of the top level of the Debianised source
9981 tree. They are described below.
9984 <sect1 id="pkg-debianrules">
9985 <heading><file>debian/rules</file> - the main building script</heading>
9988 See <ref id="debianrules">.
9993 <sect1 id="pkg-dpkgchangelog">
9994 <heading><file>debian/changelog</file></heading>
9997 See <ref id="dpkgchangelog">.
10000 <sect2><heading>Defining alternative changelog formats
10004 It is possible to use a different format to the standard
10005 one, by providing a parser for the format you wish to
10010 In order to have <tt>dpkg-parsechangelog</tt> run your
10011 parser, you must include a line within the last 40 lines
10012 of your file matching the Perl regular expression:
10013 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
10014 parentheses should be the name of the format. For
10015 example, you might say:
10017 @@@ changelog-format: joebloggs @@@
10019 Changelog format names are non-empty strings of alphanumerics.
10023 If such a line exists then <tt>dpkg-parsechangelog</tt>
10024 will look for the parser as
10025 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
10027 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
10028 it is an error for it not to find it, or for it not to
10029 be an executable program. The default changelog format
10030 is <tt>dpkg</tt>, and a parser for it is provided with
10031 the <tt>dpkg</tt> package.
10035 The parser will be invoked with the changelog open on
10036 standard input at the start of the file. It should read
10037 the file (it may seek if it wishes) to determine the
10038 information required and return the parsed information
10039 to standard output in the form of a series of control
10040 fields in the standard format. By default it should
10041 return information about only the most recent version in
10042 the changelog; it should accept a
10043 <tt>-v<var>version</var></tt> option to return changes
10044 information from all versions present <em>strictly
10045 after</em> <var>version</var>, and it should then be an
10046 error for <var>version</var> not to be present in the
10052 <list compact="compact">
10053 <item><qref id="f-Source"><tt>Source</tt></qref></item>
10054 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
10055 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
10056 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
10057 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
10058 <item><qref id="f-Date"><tt>Date</tt></qref></item>
10059 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
10064 If several versions are being returned (due to the use
10065 of <tt>-v</tt>), the urgency value should be of the
10066 highest urgency code listed at the start of any of the
10067 versions requested followed by the concatenated
10068 (space-separated) comments from all the versions
10069 requested; the maintainer, version, distribution and
10070 date should always be from the most recent version.
10074 For the format of the <tt>Changes</tt> field see
10075 <ref id="f-Changes">.
10079 If the changelog format which is being parsed always or
10080 almost always leaves a blank line between individual
10081 change notes these blank lines should be stripped out,
10082 so as to make the resulting output compact.
10086 If the changelog format does not contain date or package
10087 name information this information should be omitted from
10088 the output. The parser should not attempt to synthesize
10089 it or find it from other sources.
10093 If the changelog does not have the expected format the
10094 parser should exit with a nonzero exit status, rather
10095 than trying to muddle through and possibly generating
10100 A changelog parser may not interact with the user at
10106 <sect1 id="pkg-srcsubstvars">
10107 <heading><file>debian/substvars</file> and variable substitutions</heading>
10110 See <ref id="substvars">.
10116 <heading><file>debian/files</file></heading>
10119 See <ref id="debianfiles">.
10123 <sect1><heading><file>debian/tmp</file>
10127 This is the canonical temporary location for the
10128 construction of binary packages by the <tt>binary</tt>
10129 target. The directory <file>tmp</file> serves as the root of
10130 the file system tree as it is being constructed (for
10131 example, by using the package's upstream makefiles install
10132 targets and redirecting the output there), and it also
10133 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10134 id="pkg-bincreating">.
10138 If several binary packages are generated from the same
10139 source tree it is usual to use several
10140 <file>debian/tmp<var>something</var></file> directories, for
10141 example <file>tmp-a</file> or <file>tmp-doc</file>.
10145 Whatever <file>tmp</file> directories are created and used by
10146 <tt>binary</tt> must of course be removed by the
10147 <tt>clean</tt> target.</p></sect1>
10151 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10155 As it exists on the FTP site, a Debian source package
10156 consists of three related files. You must have the right
10157 versions of all three to be able to use them.
10162 <tag>Debian source control file - <tt>.dsc</tt></tag>
10164 This file is a control file used by <prgn>dpkg-source</prgn>
10165 to extract a source package.
10166 See <ref id="debiansourcecontrolfiles">.
10170 Original source archive -
10172 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10178 This is a compressed (with <tt>gzip -9</tt>)
10179 <prgn>tar</prgn> file containing the source code from
10180 the upstream authors of the program.
10185 Debianisation diff -
10187 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10193 This is a unified context diff (<tt>diff -u</tt>)
10194 giving the changes which are required to turn the
10195 original source into the Debian source. These changes
10196 may only include editing and creating plain files.
10197 The permissions of files, the targets of symbolic
10198 links and the characteristics of special files or
10199 pipes may not be changed and no files may be removed
10204 All the directories in the diff must exist, except the
10205 <file>debian</file> subdirectory of the top of the source
10206 tree, which will be created by
10207 <prgn>dpkg-source</prgn> if necessary when unpacking.
10211 The <prgn>dpkg-source</prgn> program will
10212 automatically make the <file>debian/rules</file> file
10213 executable (see below).</p></item>
10218 If there is no original source code - for example, if the
10219 package is specially prepared for Debian or the Debian
10220 maintainer is the same as the upstream maintainer - the
10221 format is slightly different: then there is no diff, and the
10223 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10224 and preferably contains a directory named
10225 <file><var>package</var>-<var>version</var></file>.
10230 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10233 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10234 Debian source package. However, if it is not available it
10235 is possible to unpack a Debian source archive as follows:
10236 <enumlist compact="compact">
10239 Untar the tarfile, which will create a <file>.orig</file>
10243 <p>Rename the <file>.orig</file> directory to
10244 <file><var>package</var>-<var>version</var></file>.</p>
10248 Create the subdirectory <file>debian</file> at the top of
10249 the source tree.</p>
10251 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10253 <item><p>Untar the tarfile again if you want a copy of the original
10254 source code alongside the Debianised version.</p>
10259 It is not possible to generate a valid Debian source archive
10260 without using <prgn>dpkg-source</prgn>. In particular,
10261 attempting to use <prgn>diff</prgn> directly to generate the
10262 <file>.diff.gz</file> file will not work.
10266 <heading>Restrictions on objects in source packages</heading>
10269 The source package may not contain any hard links
10271 This is not currently detected when building source
10272 packages, but only when extracting
10276 Hard links may be permitted at some point in the
10277 future, but would require a fair amount of
10279 </footnote>, device special files, sockets or setuid or
10282 Setgid directories are allowed.
10287 The source packaging tools manage the changes between the
10288 original and Debianised source using <prgn>diff</prgn> and
10289 <prgn>patch</prgn>. Turning the original source tree as
10290 included in the <file>.orig.tar.gz</file> into the debianised
10291 source must not involve any changes which cannot be
10292 handled by these tools. Problematic changes which cause
10293 <prgn>dpkg-source</prgn> to halt with an error when
10294 building the source package are:
10295 <list compact="compact">
10296 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10298 <item><p>Changing the targets of symbolic links.</p>
10300 <item><p>Creating directories, other than <file>debian</file>.</p>
10302 <item><p>Changes to the contents of binary files.</p></item>
10303 </list> Changes which cause <prgn>dpkg-source</prgn> to
10304 print a warning but continue anyway are:
10305 <list compact="compact">
10308 Removing files, directories or symlinks.
10310 Renaming a file is not treated specially - it is
10311 seen as the removal of the old file (which
10312 generates a warning, but is otherwise ignored),
10313 and the creation of the new one.
10319 Changed text files which are missing the usual final
10320 newline (either in the original or the modified
10325 Changes which are not represented, but which are not detected by
10326 <prgn>dpkg-source</prgn>, are:
10327 <list compact="compact">
10328 <item><p>Changing the permissions of files (other than
10329 <file>debian/rules</file>) and directories.</p></item>
10334 The <file>debian</file> directory and <file>debian/rules</file>
10335 are handled specially by <prgn>dpkg-source</prgn> - before
10336 applying the changes it will create the <file>debian</file>
10337 directory, and afterwards it will make
10338 <file>debian/rules</file> world-executable.
10344 <appendix id="pkg-controlfields">
10345 <heading>Control files and their fields (from old Packaging Manual)</heading>
10348 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10349 data in a common format, known as control files. Binary and
10350 source packages have control data as do the <file>.changes</file>
10351 files which control the installation of uploaded files, and
10352 <prgn>dpkg</prgn>'s internal databases are in a similar
10357 <heading>Syntax of control files</heading>
10360 See <ref id="controlsyntax">.
10364 It is important to note that there are several fields which
10365 are optional as far as <prgn>dpkg</prgn> and the related
10366 tools are concerned, but which must appear in every Debian
10367 package, or whose omission may cause problems.
10372 <heading>List of fields</heading>
10375 See <ref id="controlfieldslist">.
10379 This section now contains only the fields that didn't belong
10380 to the Policy manual.
10383 <sect1 id="pkg-f-Filename">
10384 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10387 These fields in <tt>Packages</tt> files give the
10388 filename(s) of (the parts of) a package in the
10389 distribution directories, relative to the root of the
10390 Debian hierarchy. If the package has been split into
10391 several parts the parts are all listed in order, separated
10396 <sect1 id="pkg-f-Size">
10397 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10400 These fields in <file>Packages</file> files give the size (in
10401 bytes, expressed in decimal) and MD5 checksum of the
10402 file(s) which make(s) up a binary package in the
10403 distribution. If the package is split into several parts
10404 the values for the parts are listed in order, separated by
10409 <sect1 id="pkg-f-Status">
10410 <heading><tt>Status</tt></heading>
10413 This field in <prgn>dpkg</prgn>'s status file records
10414 whether the user wants a package installed, removed or
10415 left alone, whether it is broken (requiring
10416 re-installation) or not and what its current state on the
10417 system is. Each of these pieces of information is a
10422 <sect1 id="pkg-f-Config-Version">
10423 <heading><tt>Config-Version</tt></heading>
10426 If a package is not installed or not configured, this
10427 field in <prgn>dpkg</prgn>'s status file records the last
10428 version of the package which was successfully
10433 <sect1 id="pkg-f-Conffiles">
10434 <heading><tt>Conffiles</tt></heading>
10437 This field in <prgn>dpkg</prgn>'s status file contains
10438 information about the automatically-managed configuration
10439 files held by a package. This field should <em>not</em>
10440 appear anywhere in a package!
10445 <heading>Obsolete fields</heading>
10448 These are still recognized by <prgn>dpkg</prgn> but should
10449 not appear anywhere any more.
10451 <taglist compact="compact">
10453 <tag><tt>Revision</tt></tag>
10454 <tag><tt>Package-Revision</tt></tag>
10455 <tag><tt>Package_Revision</tt></tag>
10457 The Debian revision part of the package version was
10458 at one point in a separate control file field. This
10459 field went through several names.
10462 <tag><tt>Recommended</tt></tag>
10463 <item>Old name for <tt>Recommends</tt>.</item>
10465 <tag><tt>Optional</tt></tag>
10466 <item>Old name for <tt>Suggests</tt>.</item>
10468 <tag><tt>Class</tt></tag>
10469 <item>Old name for <tt>Priority</tt>.</item>
10478 <appendix id="pkg-conffiles">
10479 <heading>Configuration file handling (from old Packaging Manual)</heading>
10482 <prgn>dpkg</prgn> can do a certain amount of automatic
10483 handling of package configuration files.
10487 Whether this mechanism is appropriate depends on a number of
10488 factors, but basically there are two approaches to any
10489 particular configuration file.
10493 The easy method is to ship a best-effort configuration in the
10494 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10495 handle updates. If the user is unlikely to want to edit the
10496 file, but you need them to be able to without losing their
10497 changes, and a new package with a changed version of the file
10498 is only released infrequently, this is a good approach.
10502 The hard method is to build the configuration file from
10503 scratch in the <prgn>postinst</prgn> script, and to take the
10504 responsibility for fixing any mistakes made in earlier
10505 versions of the package automatically. This will be
10506 appropriate if the file is likely to need to be different on
10510 <sect><heading>Automatic handling of configuration files by
10515 A package may contain a control area file called
10516 <tt>conffiles</tt>. This file should be a list of filenames
10517 of configuration files needing automatic handling, separated
10518 by newlines. The filenames should be absolute pathnames,
10519 and the files referred to should actually exist in the
10524 When a package is upgraded <prgn>dpkg</prgn> will process
10525 the configuration files during the configuration stage,
10526 shortly before it runs the package's <prgn>postinst</prgn>
10531 For each file it checks to see whether the version of the
10532 file included in the package is the same as the one that was
10533 included in the last version of the package (the one that is
10534 being upgraded from); it also compares the version currently
10535 installed on the system with the one shipped with the last
10540 If neither the user nor the package maintainer has changed
10541 the file, it is left alone. If one or the other has changed
10542 their version, then the changed version is preferred - i.e.,
10543 if the user edits their file, but the package maintainer
10544 doesn't ship a different version, the user's changes will
10545 stay, silently, but if the maintainer ships a new version
10546 and the user hasn't edited it the new version will be
10547 installed (with an informative message). If both have
10548 changed their version the user is prompted about the problem
10549 and must resolve the differences themselves.
10553 The comparisons are done by calculating the MD5 message
10554 digests of the files, and storing the MD5 of the file as it
10555 was included in the most recent version of the package.
10559 When a package is installed for the first time
10560 <prgn>dpkg</prgn> will install the file that comes with it,
10561 unless that would mean overwriting a file already on the
10566 However, note that <prgn>dpkg</prgn> will <em>not</em>
10567 replace a conffile that was removed by the user (or by a
10568 script). This is necessary because with some programs a
10569 missing file produces an effect hard or impossible to
10570 achieve in another way, so that a missing file needs to be
10571 kept that way if the user did it.
10575 Note that a package should <em>not</em> modify a
10576 <prgn>dpkg</prgn>-handled conffile in its maintainer
10577 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10578 the user confusing and possibly dangerous options for
10579 conffile update when the package is upgraded.</p>
10582 <sect><heading>Fully-featured maintainer script configuration
10587 For files which contain site-specific information such as
10588 the hostname and networking details and so forth, it is
10589 better to create the file in the package's
10590 <prgn>postinst</prgn> script.
10594 This will typically involve examining the state of the rest
10595 of the system to determine values and other information, and
10596 may involve prompting the user for some information which
10597 can't be obtained some other way.
10601 When using this method there are a couple of important
10602 issues which should be considered:
10606 If you discover a bug in the program which generates the
10607 configuration file, or if the format of the file changes
10608 from one version to the next, you will have to arrange for
10609 the postinst script to do something sensible - usually this
10610 will mean editing the installed configuration file to remove
10611 the problem or change the syntax. You will have to do this
10612 very carefully, since the user may have changed the file,
10613 perhaps to fix the very problem that your script is trying
10614 to deal with - you will have to detect these situations and
10615 deal with them correctly.
10619 If you do go down this route it's probably a good idea to
10620 make the program that generates the configuration file(s) a
10621 separate program in <file>/usr/sbin</file>, by convention called
10622 <file><var>package</var>config</file> and then run that if
10623 appropriate from the post-installation script. The
10624 <tt><var>package</var>config</tt> program should not
10625 unquestioningly overwrite an existing configuration - if its
10626 mode of operation is geared towards setting up a package for
10627 the first time (rather than any arbitrary reconfiguration
10628 later) you should have it check whether the configuration
10629 already exists, and require a <tt>--force</tt> flag to
10630 overwrite it.</p></sect>
10633 <appendix id="pkg-alternatives"><heading>Alternative versions of
10634 an interface - <prgn>update-alternatives</prgn> (from old
10639 When several packages all provide different versions of the
10640 same program or file it is useful to have the system select a
10641 default, but to allow the system administrator to change it
10642 and have their decisions respected.
10646 For example, there are several versions of the <prgn>vi</prgn>
10647 editor, and there is no reason to prevent all of them from
10648 being installed at once, each under their own name
10649 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10650 Nevertheless it is desirable to have the name <tt>vi</tt>
10651 refer to something, at least by default.
10655 If all the packages involved cooperate, this can be done with
10656 <prgn>update-alternatives</prgn>.
10660 Each package provides its own version under its own name, and
10661 calls <prgn>update-alternatives</prgn> in its postinst to
10662 register its version (and again in its prerm to deregister
10667 See the man page <manref name="update-alternatives"
10668 section="8"> for details.
10672 If <prgn>update-alternatives</prgn> does not seem appropriate
10673 you may wish to consider using diversions instead.</p>
10676 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10677 package's version of a file (from old Packaging Manual)
10681 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10682 when it reinstalls the package it belongs to, and to have it
10683 put the file from the package somewhere else instead.
10687 This can be used locally to override a package's version of a
10688 file, or by one package to override another's version (or
10689 provide a wrapper for it).
10693 Before deciding to use a diversion, read <ref
10694 id="pkg-alternatives"> to see if you really want a diversion
10695 rather than several alternative versions of a program.
10699 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10700 and updated by a special program <prgn>dpkg-divert</prgn>.
10701 Please see <manref name="dpkg-divert" section="8"> for full
10702 details of its operation.
10706 When a package wishes to divert a file from another, it should
10707 call <prgn>dpkg-divert</prgn> in its preinst to add the
10708 diversion and rename the existing file. For example,
10709 supposing that a <prgn>smailwrapper</prgn> package wishes to
10710 install a wrapper around <file>/usr/sbin/smail</file>:
10712 dpkg-divert --package smailwrapper --add --rename \
10713 --divert /usr/sbin/smail.real /usr/sbin/smail
10714 </example> The <tt>--package smailwrapper</tt> ensures that
10715 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10716 can bypass the diversion and get installed as the true version.
10717 It's safe to add the diversion unconditionally on upgrades since
10718 it will be left unchanged if it already exists, but
10719 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10720 message, make the command conditional on the version from which
10721 the package is being upgraded:
10723 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10724 dpkg-divert --package smailwrapper --add --rename \
10725 --divert /usr/sbin/smail.real /usr/sbin/smail
10727 </example> where <tt>1.0-2</tt> is the version at which the
10728 diversion was first added to the package. Running the command
10729 during abort-upgrade is pointless but harmless.
10733 The postrm has to do the reverse:
10735 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10736 dpkg-divert --package smailwrapper --remove --rename \
10737 --divert /usr/sbin/smail.real /usr/sbin/smail
10739 </example> If the diversion was added at a particular version, the
10740 postrm should also handle the failure case of upgrading from an
10741 older version (unless the older version is so old that direct
10742 upgrades are no longer supported):
10744 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10745 dpkg-divert --package smailwrapper --remove --rename \
10746 --divert /usr/sbin/smail.real /usr/sbin/smail
10748 </example> where <tt>1.02-2</tt> is the version at which the
10749 diversion was first added to the package. The postrm should not
10750 remove the diversion on upgrades both because there's no reason to
10751 remove the diversion only to immediately re-add it and since the
10752 postrm of the old package is run after unpacking so the removal of
10753 the diversion will fail.
10757 Do not attempt to divert a file which is vitally important for
10758 the system's operation - when using <prgn>dpkg-divert</prgn>
10759 there is a time, after it has been diverted but before
10760 <prgn>dpkg</prgn> has installed the new version, when the file
10761 does not exist.</p>
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