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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interfaces not changing, and the package
94 management software authors need to ensure
95 compatibility with these interface
96 definitions. (Control file and changelog file
97 formats are examples.)
99 <tag>Chosen Convention</tag>
101 If there are a number of technically viable choices
102 that can be made, but one needs to select one of
103 these options for inter-operability. The version
104 number format is one example.
107 Please note that these are not mutually exclusive;
108 selected conventions often become parts of standard
114 The footnotes present in this manual are
115 merely informative, and are not part of Debian policy itself.
119 The appendices to this manual are not necessarily normative,
120 either. Please see <ref id="pkg-scope"> for more information.
124 In the normative part of this manual,
125 the words <em>must</em>, <em>should</em> and
126 <em>may</em>, and the adjectives <em>required</em>,
127 <em>recommended</em> and <em>optional</em>, are used to
128 distinguish the significance of the various guidelines in
129 this policy document. Packages that do not conform to the
130 guidelines denoted by <em>must</em> (or <em>required</em>)
131 will generally not be considered acceptable for the Debian
132 distribution. Non-conformance with guidelines denoted by
133 <em>should</em> (or <em>recommended</em>) will generally be
134 considered a bug, but will not necessarily render a package
135 unsuitable for distribution. Guidelines denoted by
136 <em>may</em> (or <em>optional</em>) are truly optional and
137 adherence is left to the maintainer's discretion.
141 These classifications are roughly equivalent to the bug
142 severities <em>serious</em> (for <em>must</em> or
143 <em>required</em> directive violations), <em>minor</em>,
144 <em>normal</em> or <em>important</em>
145 (for <em>should</em> or <em>recommended</em> directive
146 violations) and <em>wishlist</em> (for <em>optional</em>
149 Compare RFC 2119. Note, however, that these words are
150 used in a different way in this document.
155 Much of the information presented in this manual will be
156 useful even when building a package which is to be
157 distributed in some other way or is intended for local use
163 <heading>New versions of this document</heading>
166 This manual is distributed via the Debian package
167 <package><url name="debian-policy"
168 id="http://packages.debian.org/debian-policy"></package>
169 (<httpsite>packages.debian.org</httpsite>
170 <httppath>/debian-policy</httppath>).
174 The current version of this document is also available from
175 the Debian web mirrors at
176 <tt><url name="/doc/debian-policy/"
177 id="http://www.debian.org/doc/debian-policy/"></tt>.
179 <httpsite>www.debian.org</httpsite>
180 <httppath>/doc/debian-policy/</httppath>)
181 Also available from the same directory are several other
182 formats: <file>policy.html.tar.gz</file>
183 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
184 <file>policy.pdf.gz</file>
185 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
186 and <file>policy.ps.gz</file>
187 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
191 The <package>debian-policy</package> package also includes the file
192 <file>upgrading-checklist.txt.gz</file> which indicates policy
193 changes between versions of this document.
198 <heading>Authors and Maintainers</heading>
201 Originally called "Debian GNU/Linux Policy Manual", this
202 manual was initially written in 1996 by Ian Jackson.
203 It was revised on November 27th, 1996 by David A. Morris.
204 Christian Schwarz added new sections on March 15th, 1997,
205 and reworked/restructured it in April-July 1997.
206 Christoph Lameter contributed the "Web Standard".
207 Julian Gilbey largely restructured it in 2001.
211 Since September 1998, the responsibility for the contents of
212 this document lies on the <url name="debian-policy mailing list"
213 id="mailto:debian-policy@lists.debian.org">. Proposals
214 are discussed there and inserted into policy after a certain
215 consensus is established.
216 <!-- insert shameless policy-process plug here eventually -->
217 The actual editing is done by a group of maintainers that have
218 no editorial powers. These are the current maintainers:
221 <item>Julian Gilbey</item>
222 <item>Branden Robinson</item>
223 <item>Josip Rodin</item>
224 <item>Manoj Srivastava</item>
229 While the authors of this document have tried hard to avoid
230 typos and other errors, these do still occur. If you discover
231 an error in this manual or if you want to give any
232 comments, suggestions, or criticisms please send an email to
233 the Debian Policy List,
234 <email>debian-policy@lists.debian.org</email>, or submit a
235 bug report against the <tt>debian-policy</tt> package.
239 Please do not try to reach the individual authors or maintainers
240 of the Policy Manual regarding changes to the Policy.
245 <heading>Related documents</heading>
248 There are several other documents other than this Policy Manual
249 that are necessary to fully understand some Debian policies and
254 The external "sub-policy" documents are referred to in:
255 <list compact="compact">
256 <item><ref id="fhs"></item>
257 <item><ref id="virtual_pkg"></item>
258 <item><ref id="menus"></item>
259 <item><ref id="mime"></item>
260 <item><ref id="perl"></item>
261 <item><ref id="maintscriptprompt"></item>
262 <item><ref id="emacs"></item>
267 In addition to those, which carry the weight of policy, there
268 is the Debian Developer's Reference. This document describes
269 procedures and resources for Debian developers, but it is
270 <em>not</em> normative; rather, it includes things that don't
271 belong in the Policy, such as best practices for developers.
275 The Developer's Reference is available in the
276 <package>developers-reference</package> package.
277 It's also available from the Debian web mirrors at
278 <tt><url name="/doc/developers-reference/"
279 id="http://www.debian.org/doc/developers-reference/"></tt>.
283 <sect id="definitions">
284 <heading>Definitions</heading>
287 The following terms are used in this Policy Manual:
291 The character encoding specified by ANSI X3.4-1986 and its
292 predecessor standards, referred to in MIME as US-ASCII, and
293 corresponding to an encoding in eight bits per character of
294 the first 128 <url id="http://www.unicode.org/"
295 name="Unicode"> characters, with the eighth bit always zero.
299 The transformation format (sometimes called encoding) of
300 <url id="http://www.unicode.org/" name="Unicode"> defined by
301 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
302 name="RFC 3629">. UTF-8 has the useful property of having
303 ASCII as a subset, so any text encoded in ASCII is trivially
313 <heading>The Debian Archive</heading>
316 The Debian GNU/Linux system is maintained and distributed as a
317 collection of <em>packages</em>. Since there are so many of
318 them (currently well over 15000), they are split into
319 <em>sections</em> and given <em>priorities</em> to simplify
320 the handling of them.
324 The effort of the Debian project is to build a free operating
325 system, but not every package we want to make accessible is
326 <em>free</em> in our sense (see the Debian Free Software
327 Guidelines, below), or may be imported/exported without
328 restrictions. Thus, the archive is split into areas<footnote>
329 The Debian archive software uses the term "component" internally
330 and in the Release file format to refer to the division of an
331 archive. The Debian Social Contract simply refers to "areas."
332 This document uses terminology similar to the Social Contract.
333 </footnote> based on their licenses and other restrictions.
337 The aims of this are:
339 <list compact="compact">
340 <item>to allow us to make as much software available as we can</item>
341 <item>to allow us to encourage everyone to write free software,
343 <item>to allow us to make it easy for people to produce
344 CD-ROMs of our system without violating any licenses,
345 import/export restrictions, or any other laws.</item>
350 The <em>main</em> archive area forms the <em>Debian GNU/Linux
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 Every package in <em>main</em> must comply with the DFSG
469 (Debian Free Software Guidelines).
473 In addition, the packages in <em>main</em>
474 <list compact="compact">
476 must not require a package outside of <em>main</em>
477 for compilation or execution (thus, the package must
478 not declare a "Depends", "Recommends", or
479 "Build-Depends" relationship on a non-<em>main</em>
483 must not be so buggy that we refuse to support them,
487 must meet all policy requirements presented in this
496 <heading>The contrib archive area</heading>
499 Every package in <em>contrib</em> must comply with the DFSG.
503 In addition, the packages in <em>contrib</em>
504 <list compact="compact">
506 must not be so buggy that we refuse to support them,
510 must meet all policy requirements presented in this
518 Examples of packages which would be included in
519 <em>contrib</em> are:
520 <list compact="compact">
522 free packages which require <em>contrib</em>,
523 <em>non-free</em> packages or packages which are not
524 in our archive at all for compilation or execution,
528 wrapper packages or other sorts of free accessories for
535 <sect1 id="non-free">
536 <heading>The non-free archive area</heading>
539 Packages must be placed in <em>non-free</em> if they are
540 not compliant with the DFSG or are encumbered by patents
541 or other legal issues that make their distribution
546 In addition, the packages in <em>non-free</em>
547 <list compact="compact">
549 must not be so buggy that we refuse to support them,
553 must meet all policy requirements presented in this
554 manual that it is possible for them to meet.
556 It is possible that there are policy
557 requirements which the package is unable to
558 meet, for example, if the source is
559 unavailable. These situations will need to be
560 handled on a case-by-case basis.
569 <sect id="pkgcopyright">
570 <heading>Copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of
574 its copyright and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
580 We reserve the right to restrict files from being included
581 anywhere in our archives if
582 <list compact="compact">
584 their use or distribution would break a law,
587 there is an ethical conflict in their distribution or
591 we would have to sign a license for them, or
594 their distribution would conflict with other project
601 Programs whose authors encourage the user to make
602 donations are fine for the main distribution, provided
603 that the authors do not claim that not donating is
604 immoral, unethical, illegal or something similar; in such
605 a case they must go in <em>non-free</em>.
609 Packages whose copyright permission notices (or patent
610 problems) do not even allow redistribution of binaries
611 only, and where no special permission has been obtained,
612 must not be placed on the Debian FTP site and its mirrors
617 Note that under international copyright law (this applies
618 in the United States, too), <em>no</em> distribution or
619 modification of a work is allowed without an explicit
620 notice saying so. Therefore a program without a copyright
621 notice <em>is</em> copyrighted and you may not do anything
622 to it without risking being sued! Likewise if a program
623 has a copyright notice but no statement saying what is
624 permitted then nothing is permitted.
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <sect id="subsections">
649 <heading>Sections</heading>
652 The packages in the archive areas <em>main</em>,
653 <em>contrib</em> and <em>non-free</em> are grouped further into
654 <em>sections</em> to simplify handling.
658 The archive area and section for each package should be
659 specified in the package's <tt>Section</tt> control record (see
660 <ref id="f-Section">). However, the maintainer of the Debian
661 archive may override this selection to ensure the consistency of
662 the Debian distribution. The <tt>Section</tt> field should be
664 <list compact="compact">
666 <em>section</em> if the package is in the
667 <em>main</em> archive area,
670 <em>area/section</em> if the package is in
671 the <em>contrib</em> or <em>non-free</em>
678 The Debian archive maintainers provide the authoritative
679 list of sections. At present, they are:
680 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
681 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
682 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
683 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
684 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
685 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
686 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
687 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
688 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
689 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
690 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
691 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
692 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
697 <sect id="priorities">
698 <heading>Priorities</heading>
701 Each package should have a <em>priority</em> value, which is
702 included in the package's <em>control record</em>
703 (see <ref id="f-Priority">).
704 This information is used by the Debian package management tools to
705 separate high-priority packages from less-important packages.
709 The following <em>priority levels</em> are recognized by the
710 Debian package management tools.
712 <tag><tt>required</tt></tag>
714 Packages which are necessary for the proper
715 functioning of the system (usually, this means that
716 dpkg functionality depends on these packages).
717 Removing a <tt>required</tt> package may cause your
718 system to become totally broken and you may not even
719 be able to use <prgn>dpkg</prgn> to put things back,
720 so only do so if you know what you are doing. Systems
721 with only the <tt>required</tt> packages are probably
722 unusable, but they do have enough functionality to
723 allow the sysadmin to boot and install more software.
725 <tag><tt>important</tt></tag>
727 Important programs, including those which one would
728 expect to find on any Unix-like system. If the
729 expectation is that an experienced Unix person who
730 found it missing would say "What on earth is going on,
731 where is <prgn>foo</prgn>?", it must be an
732 <tt>important</tt> package.<footnote>
733 This is an important criterion because we are
734 trying to produce, amongst other things, a free
737 Other packages without which the system will not run
738 well or be usable must also have priority
739 <tt>important</tt>. This does
740 <em>not</em> include Emacs, the X Window System, TeX
741 or any other large applications. The
742 <tt>important</tt> packages are just a bare minimum of
743 commonly-expected and necessary tools.
745 <tag><tt>standard</tt></tag>
747 These packages provide a reasonably small but not too
748 limited character-mode system. This is what will be
749 installed by default if the user doesn't select anything
750 else. It doesn't include many large applications.
752 <tag><tt>optional</tt></tag>
754 (In a sense everything that isn't required is
755 optional, but that's not what is meant here.) This is
756 all the software that you might reasonably want to
757 install if you didn't know what it was and don't have
758 specialized requirements. This is a much larger system
759 and includes the X Window System, a full TeX
760 distribution, and many applications. Note that
761 optional packages should not conflict with each other.
763 <tag><tt>extra</tt></tag>
765 This contains all packages that conflict with others
766 with required, important, standard or optional
767 priorities, or are only likely to be useful if you
768 already know what they are or have specialized
769 requirements (such as packages containing only detached
776 Packages must not depend on packages with lower priority
777 values (excluding build-time dependencies). In order to
778 ensure this, the priorities of one or more packages may need
787 <heading>Binary packages</heading>
790 The Debian GNU/Linux distribution is based on the Debian
791 package management system, called <prgn>dpkg</prgn>. Thus,
792 all packages in the Debian distribution must be provided
793 in the <tt>.deb</tt> file format.
797 <heading>The package name</heading>
800 Every package must have a name that's unique within the Debian
805 The package name is included in the control field
806 <tt>Package</tt>, the format of which is described
807 in <ref id="f-Package">.
808 The package name is also included as a part of the file name
809 of the <tt>.deb</tt> file.
814 <heading>The version of a package</heading>
817 Every package has a version number recorded in its
818 <tt>Version</tt> control file field, described in
819 <ref id="f-Version">.
823 The package management system imposes an ordering on version
824 numbers, so that it can tell whether packages are being up- or
825 downgraded and so that package system front end applications
826 can tell whether a package it finds available is newer than
827 the one installed on the system. The version number format
828 has the most significant parts (as far as comparison is
829 concerned) at the beginning.
833 If an upstream package has problematic version numbers they
834 should be converted to a sane form for use in the
835 <tt>Version</tt> field.
839 <heading>Version numbers based on dates</heading>
842 In general, Debian packages should use the same version
843 numbers as the upstream sources.
847 However, in some cases where the upstream version number is
848 based on a date (e.g., a development "snapshot" release) the
849 package management system cannot handle these version
850 numbers without epochs. For example, dpkg will consider
851 "96May01" to be greater than "96Dec24".
855 To prevent having to use epochs for every new upstream
856 version, the date based portion of the version number
857 should be changed to the following format in such cases:
858 "19960501", "19961224". It is up to the maintainer whether
859 they want to bother the upstream maintainer to change
860 the version numbers upstream, too.
864 Note that other version formats based on dates which are
865 parsed correctly by the package management system should
866 <em>not</em> be changed.
870 Native Debian packages (i.e., packages which have been
871 written especially for Debian) whose version numbers include
872 dates should always use the "YYYYMMDD" format.
879 <heading>The maintainer of a package</heading>
882 Every package must have a Debian maintainer (the
883 maintainer may be one person or a group of people
884 reachable from a common email address, such as a mailing
885 list). The maintainer is responsible for ensuring that
886 the package is placed in the appropriate distributions.
890 The maintainer must be specified in the
891 <tt>Maintainer</tt> control field with their correct name
892 and a working email address. If one person maintains
893 several packages, they should try to avoid having
894 different forms of their name and email address in
895 the <tt>Maintainer</tt> fields of those packages.
899 The format of the <tt>Maintainer</tt> control field is
900 described in <ref id="f-Maintainer">.
904 If the maintainer of a package quits from the Debian
905 project, "Debian QA Group"
906 <email>packages@qa.debian.org</email> takes over the
907 maintainer-ship of the package until someone else
908 volunteers for that task. These packages are called
909 <em>orphaned packages</em>.<footnote>
910 The detailed procedure for doing this gracefully can
911 be found in the Debian Developer's Reference,
912 see <ref id="related">.
917 <sect id="descriptions">
918 <heading>The description of a package</heading>
921 Every Debian package must have an extended description
922 stored in the appropriate field of the control record.
923 The technical information about the format of the
924 <tt>Description</tt> field is in <ref id="f-Description">.
928 The description should describe the package (the program) to a
929 user (system administrator) who has never met it before so that
930 they have enough information to decide whether they want to
931 install it. This description should not just be copied verbatim
932 from the program's documentation.
936 Put important information first, both in the synopsis and
937 extended description. Sometimes only the first part of the
938 synopsis or of the description will be displayed. You can
939 assume that there will usually be a way to see the whole
940 extended description.
944 The description should also give information about the
945 significant dependencies and conflicts between this package
946 and others, so that the user knows why these dependencies and
947 conflicts have been declared.
951 Instructions for configuring or using the package should
952 not be included (that is what installation scripts,
953 manual pages, info files, etc., are for). Copyright
954 statements and other administrivia should not be included
955 either (that is what the copyright file is for).
958 <sect1 id="synopsis"><heading>The single line synopsis</heading>
961 The single line synopsis should be kept brief - certainly
966 Do not include the package name in the synopsis line. The
967 display software knows how to display this already, and you
968 do not need to state it. Remember that in many situations
969 the user may only see the synopsis line - make it as
970 informative as you can.
975 <sect1 id="extendeddesc"><heading>The extended description</heading>
978 Do not try to continue the single line synopsis into the
979 extended description. This will not work correctly when
980 the full description is displayed, and makes no sense
981 where only the summary (the single line synopsis) is
986 The extended description should describe what the package
987 does and how it relates to the rest of the system (in terms
988 of, for example, which subsystem it is which part of).
992 The description field needs to make sense to anyone, even
993 people who have no idea about any of the things the
994 package deals with.<footnote>
995 The blurb that comes with a program in its
996 announcements and/or <prgn>README</prgn> files is
997 rarely suitable for use in a description. It is
998 usually aimed at people who are already in the
999 community where the package is used.
1008 <heading>Dependencies</heading>
1011 Every package must specify the dependency information
1012 about other packages that are required for the first to
1017 For example, a dependency entry must be provided for any
1018 shared libraries required by a dynamically-linked executable
1019 binary in a package.
1023 Packages are not required to declare any dependencies they
1024 have on other packages which are marked <tt>Essential</tt>
1025 (see below), and should not do so unless they depend on a
1026 particular version of that package.<footnote>
1028 Essential is needed in part to avoid unresolvable dependency
1029 loops on upgrade. If packages add unnecessary dependencies
1030 on packages in this set, the chances that there
1031 <strong>will</strong> be an unresolvable dependency loop
1032 caused by forcing these Essential packages to be configured
1033 first before they need to be is greatly increased. It also
1034 increases the chances that frontends will be unable to
1035 <strong>calculate</strong> an upgrade path, even if one
1039 Also, functionality is rarely ever removed from the
1040 Essential set, but <em>packages</em> have been removed from
1041 the Essential set when the functionality moved to a
1042 different package. So depending on these packages <em>just
1043 in case</em> they stop being essential does way more harm
1050 Sometimes, a package requires another package to be installed
1051 <em>and</em> configured before it can be installed. In this
1052 case, you must specify a <tt>Pre-Depends</tt> entry for
1057 You should not specify a <tt>Pre-Depends</tt> entry for a
1058 package before this has been discussed on the
1059 <tt>debian-devel</tt> mailing list and a consensus about
1060 doing that has been reached.
1064 The format of the package interrelationship control fields is
1065 described in <ref id="relationships">.
1069 <sect id="virtual_pkg">
1070 <heading>Virtual packages</heading>
1073 Sometimes, there are several packages which offer
1074 more-or-less the same functionality. In this case, it's
1075 useful to define a <em>virtual package</em> whose name
1076 describes that common functionality. (The virtual
1077 packages only exist logically, not physically; that's why
1078 they are called <em>virtual</em>.) The packages with this
1079 particular function will then <em>provide</em> the virtual
1080 package. Thus, any other package requiring that function
1081 can simply depend on the virtual package without having to
1082 specify all possible packages individually.
1086 All packages should use virtual package names where
1087 appropriate, and arrange to create new ones if necessary.
1088 They should not use virtual package names (except privately,
1089 amongst a cooperating group of packages) unless they have
1090 been agreed upon and appear in the list of virtual package
1091 names. (See also <ref id="virtual">)
1095 The latest version of the authoritative list of virtual
1096 package names can be found in the <tt>debian-policy</tt> package.
1097 It is also available from the Debian web mirrors at
1098 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1099 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1103 The procedure for updating the list is described in the preface
1110 <heading>Base system</heading>
1113 The <tt>base system</tt> is a minimum subset of the Debian
1114 GNU/Linux system that is installed before everything else
1115 on a new system. Only very few packages are allowed to form
1116 part of the base system, in order to keep the required disk
1121 The base system consists of all those packages with priority
1122 <tt>required</tt> or <tt>important</tt>. Many of them will
1123 be tagged <tt>essential</tt> (see below).
1128 <heading>Essential packages</heading>
1131 Essential is defined as the minimal set of functionality that
1132 must be available and usable on the system at all times, even
1133 when packages are in an unconfigured (but unpacked) state.
1134 Packages are tagged <tt>essential</tt> for a system using the
1135 <tt>Essential</tt> control file field. The format of the
1136 <tt>Essential</tt> control field is described in <ref
1141 Since these packages cannot be easily removed (one has to
1142 specify an extra <em>force option</em> to
1143 <prgn>dpkg</prgn> to do so), this flag must not be used
1144 unless absolutely necessary. A shared library package
1145 must not be tagged <tt>essential</tt>; dependencies will
1146 prevent its premature removal, and we need to be able to
1147 remove it when it has been superseded.
1151 Since dpkg will not prevent upgrading of other packages
1152 while an <tt>essential</tt> package is in an unconfigured
1153 state, all <tt>essential</tt> packages must supply all of
1154 their core functionality even when unconfigured. If the
1155 package cannot satisfy this requirement it must not be
1156 tagged as essential, and any packages depending on this
1157 package must instead have explicit dependency fields as
1162 Maintainers should take great care in adding any programs,
1163 interfaces, or functionality to <tt>essential</tt> packages.
1164 Packages may assume that functionality provided by
1165 <tt>essential</tt> packages is always available without
1166 declaring explicit dependencies, which means that removing
1167 functionality from the Essential set is very difficult and is
1168 almost never done. Any capability added to an
1169 <tt>essential</tt> package therefore creates an obligation to
1170 support that capability as part of the Essential set in
1175 You must not tag any packages <tt>essential</tt> before
1176 this has been discussed on the <tt>debian-devel</tt>
1177 mailing list and a consensus about doing that has been
1182 <sect id="maintscripts">
1183 <heading>Maintainer Scripts</heading>
1186 The package installation scripts should avoid producing
1187 output which is unnecessary for the user to see and
1188 should rely on <prgn>dpkg</prgn> to stave off boredom on
1189 the part of a user installing many packages. This means,
1190 amongst other things, using the <tt>--quiet</tt> option on
1191 <prgn>install-info</prgn>.
1195 Errors which occur during the execution of an installation
1196 script must be checked and the installation must not
1197 continue after an error.
1201 Note that in general <ref id="scripts"> applies to package
1202 maintainer scripts, too.
1206 You should not use <prgn>dpkg-divert</prgn> on a file
1207 belonging to another package without consulting the
1208 maintainer of that package first.
1212 All packages which supply an instance of a common command
1213 name (or, in general, filename) should generally use
1214 <prgn>update-alternatives</prgn>, so that they may be
1215 installed together. If <prgn>update-alternatives</prgn>
1216 is not used, then each package must use
1217 <tt>Conflicts</tt> to ensure that other packages are
1218 de-installed. (In this case, it may be appropriate to
1219 specify a conflict against earlier versions of something
1220 that previously did not use
1221 <prgn>update-alternatives</prgn>; this is an exception to
1222 the usual rule that versioned conflicts should be
1226 <sect1 id="maintscriptprompt">
1227 <heading>Prompting in maintainer scripts</heading>
1229 Package maintainer scripts may prompt the user if
1230 necessary. Prompting must be done by communicating
1231 through a program, such as <prgn>debconf</prgn>, which
1232 conforms to the Debian Configuration Management
1233 Specification, version 2 or higher.
1237 Packages which are essential, or which are dependencies of
1238 essential packages, may fall back on another prompting method
1239 if no such interface is available when they are executed.
1243 The Debian Configuration Management Specification is included
1244 in the <file>debconf_specification</file> files in the
1245 <package>debian-policy</package> package.
1246 It is also available from the Debian web mirrors at
1247 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1248 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1252 Packages which use the Debian Configuration Management
1253 Specification may contain an additional
1254 <prgn>config</prgn> script and a <tt>templates</tt>
1255 file in their control archive<footnote>
1256 The control.tar.gz inside the .deb.
1257 See <manref name="deb" section="5">.
1259 The <prgn>config</prgn> script might be run before the
1260 <prgn>preinst</prgn> script, and before the package is unpacked
1261 or any of its dependencies or pre-dependencies are satisfied.
1262 Therefore it must work using only the tools present in
1263 <em>essential</em> packages.<footnote>
1264 <package>Debconf</package> or another tool that
1265 implements the Debian Configuration Management
1266 Specification will also be installed, and any
1267 versioned dependencies on it will be satisfied
1268 before preconfiguration begins.
1273 Packages which use the Debian Configuration Management
1274 Specification must allow for translation of their user-visible
1275 messages by using a gettext-based system such as the one
1276 provided by the <package>po-debconf</package> package.
1280 Packages should try to minimize the amount of prompting
1281 they need to do, and they should ensure that the user
1282 will only ever be asked each question once. This means
1283 that packages should try to use appropriate shared
1284 configuration files (such as <file>/etc/papersize</file> and
1285 <file>/etc/news/server</file>), and shared
1286 <package>debconf</package> variables rather than each
1287 prompting for their own list of required pieces of
1292 It also means that an upgrade should not ask the same
1293 questions again, unless the user has used
1294 <tt>dpkg --purge</tt> to remove the package's configuration.
1295 The answers to configuration questions should be stored in an
1296 appropriate place in <file>/etc</file> so that the user can
1297 modify them, and how this has been done should be
1302 If a package has a vitally important piece of
1303 information to pass to the user (such as "don't run me
1304 as I am, you must edit the following configuration files
1305 first or you risk your system emitting badly-formatted
1306 messages"), it should display this in the
1307 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1308 prompt the user to hit return to acknowledge the
1309 message. Copyright messages do not count as vitally
1310 important (they belong in
1311 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1312 neither do instructions on how to use a program (these
1313 should be in on-line documentation, where all the users
1318 Any necessary prompting should almost always be confined
1319 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1320 script. If it is done in the <prgn>postinst</prgn>, it
1321 should be protected with a conditional so that
1322 unnecessary prompting doesn't happen if a package's
1323 installation fails and the <prgn>postinst</prgn> is
1324 called with <tt>abort-upgrade</tt>,
1325 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1335 <heading>Source packages</heading>
1337 <sect id="standardsversion">
1338 <heading>Standards conformance</heading>
1341 Source packages should specify the most recent version number
1342 of this policy document with which your package complied
1343 when it was last updated.
1347 This information may be used to file bug reports
1348 automatically if your package becomes too much out of date.
1352 The version is specified in the <tt>Standards-Version</tt>
1354 The format of the <tt>Standards-Version</tt> field is
1355 described in <ref id="f-Standards-Version">.
1359 You should regularly, and especially if your package has
1360 become out of date, check for the newest Policy Manual
1361 available and update your package, if necessary. When your
1362 package complies with the new standards you should update the
1363 <tt>Standards-Version</tt> source package field and
1364 release it.<footnote>
1365 See the file <file>upgrading-checklist</file> for
1366 information about policy which has changed between
1367 different versions of this document.
1373 <sect id="pkg-relations">
1374 <heading>Package relationships</heading>
1377 Source packages should specify which binary packages they
1378 require to be installed or not to be installed in order to
1379 build correctly. For example, if building a package
1380 requires a certain compiler, then the compiler should be
1381 specified as a build-time dependency.
1385 It is not necessary to explicitly specify build-time
1386 relationships on a minimal set of packages that are always
1387 needed to compile, link and put in a Debian package a
1388 standard "Hello World!" program written in C or C++. The
1389 required packages are called <em>build-essential</em>, and
1390 an informational list can be found in
1391 <file>/usr/share/doc/build-essential/list</file> (which is
1392 contained in the <tt>build-essential</tt>
1395 <list compact="compact">
1397 This allows maintaining the list separately
1398 from the policy documents (the list does not
1399 need the kind of control that the policy
1403 Having a separate package allows one to install
1404 the build-essential packages on a machine, as
1405 well as allowing other packages such as tasks to
1406 require installation of the build-essential
1407 packages using the depends relation.
1410 The separate package allows bug reports against
1411 the list to be categorized separately from
1412 the policy management process in the BTS.
1419 When specifying the set of build-time dependencies, one
1420 should list only those packages explicitly required by the
1421 build. It is not necessary to list packages which are
1422 required merely because some other package in the list of
1423 build-time dependencies depends on them.<footnote>
1424 The reason for this is that dependencies change, and
1425 you should list all those packages, and <em>only</em>
1426 those packages that <em>you</em> need directly. What
1427 others need is their business. For example, if you
1428 only link against <file>libimlib</file>, you will need to
1429 build-depend on <package>libimlib2-dev</package> but
1430 not against any <tt>libjpeg*</tt> packages, even
1431 though <tt>libimlib2-dev</tt> currently depends on
1432 them: installation of <package>libimlib2-dev</package>
1433 will automatically ensure that all of its run-time
1434 dependencies are satisfied.
1439 If build-time dependencies are specified, it must be
1440 possible to build the package and produce working binaries
1441 on a system with only essential and build-essential
1442 packages installed and also those required to satisfy the
1443 build-time relationships (including any implied
1444 relationships). In particular, this means that version
1445 clauses should be used rigorously in build-time
1446 relationships so that one cannot produce bad or
1447 inconsistently configured packages when the relationships
1448 are properly satisfied.
1452 <ref id="relationships"> explains the technical details.
1457 <heading>Changes to the upstream sources</heading>
1460 If changes to the source code are made that are not
1461 specific to the needs of the Debian system, they should be
1462 sent to the upstream authors in whatever form they prefer
1463 so as to be included in the upstream version of the
1468 If you need to configure the package differently for
1469 Debian or for Linux, and the upstream source doesn't
1470 provide a way to do so, you should add such configuration
1471 facilities (for example, a new <prgn>autoconf</prgn> test
1472 or <tt>#define</tt>) and send the patch to the upstream
1473 authors, with the default set to the way they originally
1474 had it. You can then easily override the default in your
1475 <file>debian/rules</file> or wherever is appropriate.
1479 You should make sure that the <prgn>configure</prgn> utility
1480 detects the correct architecture specification string
1481 (refer to <ref id="arch-spec"> for details).
1485 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1486 <prgn>configure</prgn> scripts are used, you should edit the
1487 <file>.in</file> files rather than editing the
1488 <prgn>Makefile</prgn> directly. This allows the user to
1489 reconfigure the package if necessary. You should
1490 <em>not</em> configure the package and edit the generated
1491 <prgn>Makefile</prgn>! This makes it impossible for someone
1492 else to later reconfigure the package without losing the
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>.<footnote>
1506 Mistakes in changelogs are usually best rectified by
1507 making a new changelog entry rather than "rewriting
1508 history" by editing old changelog entries.
1511 This includes modifications
1512 made in the Debian package compared to the upstream one
1513 as well as other changes and updates to the package.
1515 Although there is nothing stopping an author who is also
1516 the Debian maintainer from using this changelog for all
1517 their changes, it will have to be renamed if the Debian
1518 and upstream maintainers become different people. In such
1519 a case, however, it might be better to maintain the package
1520 as a non-native package.
1525 The format of the <file>debian/changelog</file> allows the
1526 package building tools to discover which version of the package
1527 is being built and find out other release-specific information.
1531 That format is a series of entries like this:
1533 <example compact="compact">
1534 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1536 [optional blank line(s), stripped]
1538 * <var>change details</var>
1539 <var>more change details</var>
1541 [blank line(s), included in output of dpkg-parsechangelog]
1543 * <var>even more change details</var>
1545 [optional blank line(s), stripped]
1547 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1552 <var>package</var> and <var>version</var> are the source
1553 package name and version number.
1557 <var>distribution(s)</var> lists the distributions where
1558 this version should be installed when it is uploaded - it
1559 is copied to the <tt>Distribution</tt> field in the
1560 <file>.changes</file> file. See <ref id="f-Distribution">.
1564 <var>urgency</var> is the value for the <tt>Urgency</tt>
1565 field in the <file>.changes</file> file for the upload
1566 (see <ref id="f-Urgency">). It is not possible to specify
1567 an urgency containing commas; commas are used to separate
1568 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1569 <prgn>dpkg</prgn> changelog format (though there is
1570 currently only one useful <var>keyword</var>,
1575 The change details may in fact be any series of lines
1576 starting with at least two spaces, but conventionally each
1577 change starts with an asterisk and a separating space and
1578 continuation lines are indented so as to bring them in
1579 line with the start of the text above. Blank lines may be
1580 used here to separate groups of changes, if desired.
1584 If this upload resolves bugs recorded in the Bug Tracking
1585 System (BTS), they may be automatically closed on the
1586 inclusion of this package into the Debian archive by
1587 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1588 in the change details.<footnote>
1589 To be precise, the string should match the following
1590 Perl regular expression:
1592 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1594 Then all of the bug numbers listed will be closed by the
1595 archive maintenance script (<prgn>katie</prgn>) using the
1596 <var>version</var> of the changelog entry.
1598 This information is conveyed via the <tt>Closes</tt> field
1599 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1603 The maintainer name and email address used in the changelog
1604 should be the details of the person uploading <em>this</em>
1605 version. They are <em>not</em> necessarily those of the
1606 usual package maintainer. The information here will be
1607 copied to the <tt>Changed-By</tt> field in the
1608 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1609 and then later used to send an acknowledgement when the
1610 upload has been installed.
1614 The <var>date</var> must be in RFC822 format<footnote>
1615 This is generated by <tt>date -R</tt>.
1616 </footnote>; it must include the time zone specified
1617 numerically, with the time zone name or abbreviation
1618 optionally present as a comment in parentheses.
1622 The first "title" line with the package name must start
1623 at the left hand margin. The "trailer" line with the
1624 maintainer and date details must be preceded by exactly
1625 one space. The maintainer details and the date must be
1626 separated by exactly two spaces.
1630 The entire changelog must be encoded in UTF-8.
1634 For more information on placement of the changelog files
1635 within binary packages, please see <ref id="changelogs">.
1639 <sect id="dpkgcopyright">
1640 <heading>Copyright: <file>debian/copyright</file></heading>
1642 Every package must be accompanied by a verbatim copy of
1643 its copyright and distribution license in the file
1644 <file>/usr/share/doc/<var>package</var>/copyright</file>
1645 (see <ref id="copyrightfile"> for further details). Also see
1646 <ref id="pkgcopyright"> for further considerations relayed
1647 to copyrights for packages.
1651 <heading>Error trapping in makefiles</heading>
1654 When <prgn>make</prgn> invokes a command in a makefile
1655 (including your package's upstream makefiles and
1656 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1657 means that <prgn>sh</prgn>'s usual bad error handling
1658 properties apply: if you include a miniature script as one
1659 of the commands in your makefile you'll find that if you
1660 don't do anything about it then errors are not detected
1661 and <prgn>make</prgn> will blithely continue after
1666 Every time you put more than one shell command (this
1667 includes using a loop) in a makefile command you
1668 must make sure that errors are trapped. For
1669 simple compound commands, such as changing directory and
1670 then running a program, using <tt>&&</tt> rather
1671 than semicolon as a command separator is sufficient. For
1672 more complex commands including most loops and
1673 conditionals you should include a separate <tt>set -e</tt>
1674 command at the start of every makefile command that's
1675 actually one of these miniature shell scripts.
1679 <sect id="timestamps">
1680 <heading>Time Stamps</heading>
1682 Maintainers should preserve the modification times of the
1683 upstream source files in a package, as far as is reasonably
1685 The rationale is that there is some information conveyed
1686 by knowing the age of the file, for example, you could
1687 recognize that some documentation is very old by looking
1688 at the modification time, so it would be nice if the
1689 modification time of the upstream source would be
1695 <sect id="restrictions">
1696 <heading>Restrictions on objects in source packages</heading>
1699 The source package may not contain any hard links<footnote>
1701 This is not currently detected when building source
1702 packages, but only when extracting
1706 Hard links may be permitted at some point in the
1707 future, but would require a fair amount of
1710 </footnote>, device special files, sockets or setuid or
1711 setgid files.<footnote>
1712 Setgid directories are allowed.
1717 <sect id="debianrules">
1718 <heading>Main building script: <file>debian/rules</file></heading>
1721 This file must be an executable makefile, and contains the
1722 package-specific recipes for compiling the package and
1723 building binary package(s) from the source.
1727 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1728 so that it can be invoked by saying its name rather than
1729 invoking <prgn>make</prgn> explicitly.
1733 Since an interactive <file>debian/rules</file> script makes it
1734 impossible to auto-compile that package and also makes it
1735 hard for other people to reproduce the same binary
1736 package, all <em>required targets</em> MUST be
1737 non-interactive. At a minimum, required targets are the
1738 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1739 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1740 <em>binary-indep</em>, and <em>build</em>. It also follows
1741 that any target that these targets depend on must also be
1746 The targets are as follows (required unless stated otherwise):
1748 <tag><tt>build</tt></tag>
1751 The <tt>build</tt> target should perform all the
1752 configuration and compilation of the package.
1753 If a package has an interactive pre-build
1754 configuration routine, the Debianized source package
1755 must either be built after this has taken place (so
1756 that the binary package can be built without rerunning
1757 the configuration) or the configuration routine
1758 modified to become non-interactive. (The latter is
1759 preferable if there are architecture-specific features
1760 detected by the configuration routine.)
1764 For some packages, notably ones where the same
1765 source tree is compiled in different ways to produce
1766 two binary packages, the <tt>build</tt> target
1767 does not make much sense. For these packages it is
1768 good enough to provide two (or more) targets
1769 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1770 for each of the ways of building the package, and a
1771 <tt>build</tt> target that does nothing. The
1772 <tt>binary</tt> target will have to build the
1773 package in each of the possible ways and make the
1774 binary package out of each.
1778 The <tt>build</tt> target must not do anything
1779 that might require root privilege.
1783 The <tt>build</tt> target may need to run the
1784 <tt>clean</tt> target first - see below.
1788 When a package has a configuration and build routine
1789 which takes a long time, or when the makefiles are
1790 poorly designed, or when <tt>build</tt> needs to
1791 run <tt>clean</tt> first, it is a good idea to
1792 <tt>touch build</tt> when the build process is
1793 complete. This will ensure that if <tt>debian/rules
1794 build</tt> is run again it will not rebuild the whole
1796 Another common way to do this is for <tt>build</tt>
1797 to depend on <prgn>build-stamp</prgn> and to do
1798 nothing else, and for the <prgn>build-stamp</prgn>
1799 target to do the building and to <tt>touch
1800 build-stamp</tt> on completion. This is
1801 especially useful if the build routine creates a
1802 file or directory called <tt>build</tt>; in such a
1803 case, <tt>build</tt> will need to be listed as
1804 a phony target (i.e., as a dependency of the
1805 <tt>.PHONY</tt> target). See the documentation of
1806 <prgn>make</prgn> for more information on phony
1812 <tag><tt>build-arch</tt> (optional),
1813 <tt>build-indep</tt> (optional)
1817 A package may also provide both of the targets
1818 <tt>build-arch</tt> and <tt>build-indep</tt>.
1819 The <tt>build-arch</tt> target, if provided, should
1820 perform all the configuration and compilation required
1821 for producing all architecture-dependant binary packages
1822 (those packages for which the body of the
1823 <tt>Architecture</tt> field in <tt>debian/control</tt>
1824 is not <tt>all</tt>).
1825 Similarly, the <tt>build-indep</tt> target, if
1826 provided, should perform all the configuration and
1827 compilation required for producing all
1828 architecture-independent binary packages
1829 (those packages for which the body of the
1830 <tt>Architecture</tt> field in <tt>debian/control</tt>
1832 The <tt>build</tt> target should depend on those of the
1833 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1834 are provided in the rules file.
1838 If one or both of the targets <tt>build-arch</tt> and
1839 <tt>build-indep</tt> are not provided, then invoking
1840 <file>debian/rules</file> with one of the not-provided
1841 targets as arguments should produce a exit status code
1842 of 2. Usually this is provided automatically by make
1843 if the target is missing.
1847 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1848 must not do anything that might require root privilege.
1852 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1853 <tt>binary-indep</tt>
1857 The <tt>binary</tt> target must be all that is
1858 necessary for the user to build the binary package(s)
1859 produced from this source package. It is
1860 split into two parts: <prgn>binary-arch</prgn> builds
1861 the binary packages which are specific to a particular
1862 architecture, and <tt>binary-indep</tt> builds
1863 those which are not.
1866 <tt>binary</tt> may be (and commonly is) a target with
1867 no commands which simply depends on
1868 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1871 Both <tt>binary-*</tt> targets should depend on the
1872 <tt>build</tt> target, or on the appropriate
1873 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1874 provided, so that the package is built if it has not
1875 been already. It should then create the relevant
1876 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1877 make their control files and <prgn>dpkg-deb</prgn> to
1878 build them and place them in the parent of the top
1883 Both the <tt>binary-arch</tt> and
1884 <tt>binary-indep</tt> targets <em>must</em> exist.
1885 If one of them has nothing to do (which will always be
1886 the case if the source generates only a single binary
1887 package, whether architecture-dependent or not), it
1888 must still exist and must always succeed.
1892 The <tt>binary</tt> targets must be invoked as
1894 The <prgn>fakeroot</prgn> package often allows one
1895 to build a package correctly even without being
1901 <tag><tt>clean</tt></tag>
1904 This must undo any effects that the <tt>build</tt>
1905 and <tt>binary</tt> targets may have had, except
1906 that it should leave alone any output files created in
1907 the parent directory by a run of a <tt>binary</tt>
1912 If a <tt>build</tt> file is touched at the end of
1913 the <tt>build</tt> target, as suggested above, it
1914 should be removed as the first action that
1915 <tt>clean</tt> performs, so that running
1916 <tt>build</tt> again after an interrupted
1917 <tt>clean</tt> doesn't think that everything is
1922 The <tt>clean</tt> target may need to be
1923 invoked as root if <tt>binary</tt> has been
1924 invoked since the last <tt>clean</tt>, or if
1925 <tt>build</tt> has been invoked as root (since
1926 <tt>build</tt> may create directories, for
1931 <tag><tt>get-orig-source</tt> (optional)</tag>
1934 This target fetches the most recent version of the
1935 original source package from a canonical archive site
1936 (via FTP or WWW, for example), does any necessary
1937 rearrangement to turn it into the original source
1938 tar file format described below, and leaves it in the
1943 This target may be invoked in any directory, and
1944 should take care to clean up any temporary files it
1949 This target is optional, but providing it if
1950 possible is a good idea.
1954 <tag><tt>patch</tt> (optional)</tag>
1957 This target performs whatever additional actions are
1958 required to make the source ready for editing (unpacking
1959 additional upstream archives, applying patches, etc.).
1960 It is recommended to be implemented for any package where
1961 <tt>dpkg-source -x</tt> does not result in source ready
1962 for additional modification. See
1963 <ref id="readmesource">.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
1999 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2002 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2003 specification string)
2006 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2007 <tt>DEB_*_GNU_TYPE</tt>)
2010 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2011 <tt>DEB_*_GNU_TYPE</tt>)
2013 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2014 the build machine or <tt>HOST</tt> for specification of the
2019 Backward compatibility can be provided in the rules file
2020 by setting the needed variables to suitable default
2021 values; please refer to the documentation of
2022 <prgn>dpkg-architecture</prgn> for details.
2026 It is important to understand that the <tt>DEB_*_ARCH</tt>
2027 string only determines which Debian architecture we are
2028 building on or for. It should not be used to get the CPU
2029 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2030 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2031 GNU style variables should generally only be used with upstream
2035 <sect1 id="debianrules-options">
2036 <heading><file>debian/rules</file> and
2037 <tt>DEB_BUILD_OPTIONS</tt></heading>
2040 Supporting the standardized environment variable
2041 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2042 contain several flags to change how a package is compiled and
2043 built. Each flag must be in the form <var>flag</var> or
2044 <var>flag</var>=<var>options</var>. If multiple flags are
2045 given, they must be separated by whitespace.<footnote>
2046 Some packages support any delimiter, but whitespace is the
2047 easiest to parse inside a makefile and avoids ambiguity with
2048 flag values that contain commas.
2050 <var>flag</var> must start with a lowercase letter
2051 (<tt>a-z</tt>) and consist only of lowercase letters,
2052 numbers (<tt>0-9</tt>), and the characters
2053 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2054 <var>options</var> must not contain whitespace. The same
2055 tag should not be given multiple times with conflicting
2056 values. Package maintainers may assume that
2057 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2061 The meaning of the following tags has been standardized:
2065 This tag says to not run any build-time test suite
2066 provided by the package.
2070 The presence of this tag means that the package should
2071 be compiled with a minimum of optimization. For C
2072 programs, it is best to add <tt>-O0</tt> to
2073 <tt>CFLAGS</tt> (although this is usually the default).
2074 Some programs might fail to build or run at this level
2075 of optimization; it may be necessary to use
2076 <tt>-O1</tt>, for example.
2080 This tag means that the debugging symbols should not be
2081 stripped from the binary during installation, so that
2082 debugging information may be included in the package.
2084 <tag>parallel=n</tag>
2086 This tag means that the package should be built using up
2087 to <tt>n</tt> parallel processes if the package build
2088 system supports this.<footnote>
2089 Packages built with <tt>make</tt> can often implement
2090 this by passing the <tt>-j</tt><var>n</var> option to
2093 If the package build system does not support parallel
2094 builds, this string must be ignored. If the package
2095 build system only supports a lower level of concurrency
2096 than <var>n</var>, the package should be built using as
2097 many parallel processes as the package build system
2098 supports. It is up to the package maintainer to decide
2099 whether the package build times are long enough and the
2100 package build system is robust enough to make supporting
2101 parallel builds worthwhile.
2107 Unknown flags must be ignored by <file>debian/rules</file>.
2111 The following makefile snippet is an example of how one may
2112 implement the build options; you will probably have to
2113 massage this example in order to make it work for your
2115 <example compact="compact">
2118 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2119 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2120 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2121 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2123 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2128 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2129 INSTALL_PROGRAM += -s
2131 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2132 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2133 MAKEFLAGS += -j$(NUMJOBS)
2138 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2139 # Code to run the package test suite.
2146 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2147 <sect id="substvars">
2148 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2151 When <prgn>dpkg-gencontrol</prgn>,
2152 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2153 generate control files they perform variable substitutions
2154 on their output just before writing it. Variable
2155 substitutions have the form <tt>${<var>variable</var>}</tt>.
2156 The optional file <file>debian/substvars</file> contains
2157 variable substitutions to be used; variables can also be set
2158 directly from <file>debian/rules</file> using the <tt>-V</tt>
2159 option to the source packaging commands, and certain
2160 predefined variables are also available.
2164 The <file>debian/substvars</file> file is usually generated and
2165 modified dynamically by <file>debian/rules</file> targets, in
2166 which case it must be removed by the <tt>clean</tt> target.
2170 See <manref name="deb-substvars" section="5"> for full
2171 details about source variable substitutions, including the
2172 format of <file>debian/substvars</file>.</p>
2175 <sect id="debianwatch">
2176 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2179 This is an optional, recommended control file for the
2180 <tt>uscan</tt> utility which defines how to automatically
2181 scan ftp or http sites for newly available updates of the
2182 package. This is used by <url id="
2183 http://dehs.alioth.debian.org/"> and other Debian QA tools
2184 to help with quality control and maintenance of the
2185 distribution as a whole.
2190 <sect id="debianfiles">
2191 <heading>Generated files list: <file>debian/files</file></heading>
2194 This file is not a permanent part of the source tree; it
2195 is used while building packages to record which files are
2196 being generated. <prgn>dpkg-genchanges</prgn> uses it
2197 when it generates a <file>.changes</file> file.
2201 It should not exist in a shipped source package, and so it
2202 (and any backup files or temporary files such as
2203 <file>files.new</file><footnote>
2204 <file>files.new</file> is used as a temporary file by
2205 <prgn>dpkg-gencontrol</prgn> and
2206 <prgn>dpkg-distaddfile</prgn> - they write a new
2207 version of <tt>files</tt> here before renaming it,
2208 to avoid leaving a corrupted copy if an error
2210 </footnote>) should be removed by the
2211 <tt>clean</tt> target. It may also be wise to
2212 ensure a fresh start by emptying or removing it at the
2213 start of the <tt>binary</tt> target.
2217 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2218 package, it adds an entry to <file>debian/files</file> for the
2219 <file>.deb</file> file that will be created when <tt>dpkg-deb
2220 --build</tt> is run for that binary package. So for most
2221 packages all that needs to be done with this file is to
2222 delete it in the <tt>clean</tt> target.
2226 If a package upload includes files besides the source
2227 package and any binary packages whose control files were
2228 made with <prgn>dpkg-gencontrol</prgn> then they should be
2229 placed in the parent of the package's top-level directory
2230 and <prgn>dpkg-distaddfile</prgn> should be called to add
2231 the file to the list in <file>debian/files</file>.</p>
2234 <sect id="embeddedfiles">
2235 <heading>Convenience copies of code</heading>
2238 Some software packages include in their distribution convenience
2239 copies of code from other software packages, generally so that
2240 users compiling from source don't have to download multiple
2241 packages. Debian packages should not make use of these
2242 convenience copies unless the included package is explicitly
2243 intended to be used in this way.<footnote>
2244 For example, parts of the GNU build system work like this.
2246 If the included code is already in the Debian archive in the
2247 form of a library, the Debian packaging should ensure that
2248 binary packages reference the libraries already in Debian and
2249 the convenience copy is not used. If the included code is not
2250 already in Debian, it should be packaged separately as a
2251 prerequisite if possible.
2253 Having multiple copies of the same code in Debian is
2254 inefficient, often creates either static linking or shared
2255 library conflicts, and, most importantly, increases the
2256 difficulty of handling security vulnerabilities in the
2262 <sect id="readmesource">
2263 <heading>Source package handling:
2264 <file>debian/README.source</file></heading>
2267 If running <prgn>dpkg-source -x</prgn> on a source package
2268 doesn't produce the source of the package, ready for editing,
2269 and allow one to make changes and run
2270 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2271 without taking any additional steps, creating a
2272 <file>debian/README.source</file> documentation file is
2273 recommended. This file should explain how to do all of the
2276 <item>Generate the fully patched source, in a form ready for
2277 editing, that would be built to create Debian
2278 packages. Doing this with a <tt>patch</tt> target in
2279 <file>debian/rules</file> is recommended; see
2280 <ref id="debianrules">.</item>
2281 <item>Modify the source and save those modifications so that
2282 they will be applied when building the package.</item>
2283 <item>Remove source modifications that are currently being
2284 applied when building the package.</item>
2285 <item>Optionally, document what steps are necessary to
2286 upgrade the Debian source package to a new upstream version,
2287 if applicable.</item>
2289 This explanation should include specific commands and mention
2290 any additional required Debian packages. It should not assume
2291 familiarity with any specific Debian packaging system or patch
2296 This explanation may refer to a documentation file installed by
2297 one of the package's build dependencies provided that the
2298 referenced documentation clearly explains these tasks and is not
2299 a general reference manual.
2303 <file>debian/README.source</file> may also include any other
2304 information that would be helpful to someone modifying the
2305 source package. Even if the package doesn't fit the above
2306 description, maintainers are encouraged to document in a
2307 <file>debian/README.source</file> file any source package with a
2308 particularly complex or unintuitive source layout or build
2309 system (for example, a package that builds the same source
2310 multiple times to generate different binary packages).
2316 <chapt id="controlfields">
2317 <heading>Control files and their fields</heading>
2320 The package management system manipulates data represented in
2321 a common format, known as <em>control data</em>, stored in
2322 <em>control files</em>.
2323 Control files are used for source packages, binary packages and
2324 the <file>.changes</file> files which control the installation
2325 of uploaded files<footnote>
2326 <prgn>dpkg</prgn>'s internal databases are in a similar
2331 <sect id="controlsyntax">
2332 <heading>Syntax of control files</heading>
2335 A control file consists of one or more paragraphs of
2337 The paragraphs are also sometimes referred to as stanzas.
2339 The paragraphs are separated by blank lines. Some control
2340 files allow only one paragraph; others allow several, in
2341 which case each paragraph usually refers to a different
2342 package. (For example, in source packages, the first
2343 paragraph refers to the source package, and later paragraphs
2344 refer to binary packages generated from the source.)
2348 Each paragraph consists of a series of data fields; each
2349 field consists of the field name, followed by a colon and
2350 then the data/value associated with that field. It ends at
2351 the end of the (logical) line. Horizontal whitespace
2352 (spaces and tabs) may occur immediately before or after the
2353 value and is ignored there; it is conventional to put a
2354 single space after the colon. For example, a field might
2356 <example compact="compact">
2359 the field name is <tt>Package</tt> and the field value
2364 Many fields' values may span several lines; in this case
2365 each continuation line must start with a space or a tab.
2366 Any trailing spaces or tabs at the end of individual
2367 lines of a field value are ignored.
2371 In fields where it is specified that lines may not wrap,
2372 only a single line of data is allowed and whitespace is not
2373 significant in a field body. Whitespace must not appear
2374 inside names (of packages, architectures, files or anything
2375 else) or version numbers, or between the characters of
2376 multi-character version relationships.
2380 Field names are not case-sensitive, but it is usual to
2381 capitalize the field names using mixed case as shown below.
2385 Blank lines, or lines consisting only of spaces and tabs,
2386 are not allowed within field values or between fields - that
2387 would mean a new paragraph.
2391 All control files must be encoded in UTF-8.
2395 <sect id="sourcecontrolfiles">
2396 <heading>Source package control files -- <file>debian/control</file></heading>
2399 The <file>debian/control</file> file contains the most vital
2400 (and version-independent) information about the source package
2401 and about the binary packages it creates.
2405 The first paragraph of the control file contains information about
2406 the source package in general. The subsequent sets each describe a
2407 binary package that the source tree builds.
2411 The fields in the general paragraph (the first one, for the source
2414 <list compact="compact">
2415 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2416 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2417 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2418 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2419 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2420 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2421 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2422 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2427 The fields in the binary package paragraphs are:
2429 <list compact="compact">
2430 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2431 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2432 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2433 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2434 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2435 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2436 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2437 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2442 The syntax and semantics of the fields are described below.
2448 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2449 generate control files for binary packages (see below), by
2450 <prgn>dpkg-genchanges</prgn> to generate the
2451 <tt>.changes</tt> file to accompany the upload, and by
2452 <prgn>dpkg-source</prgn> when it creates the
2453 <file>.dsc</file> source control file as part of a source
2454 archive. Many fields are permitted to span multiple lines in
2455 <file>debian/control</file> but not in any other control
2456 file. These tools are responsible for removing the line
2457 breaks from such fields when using fields from
2458 <file>debian/control</file> to generate other control files.
2462 The fields here may contain variable references - their
2463 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2464 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2465 when they generate output control files.
2466 See <ref id="substvars"> for details.
2470 In addition to the control file syntax described <qref
2471 id="controlsyntax">above</qref>, this file may also contain
2472 comment lines starting with <tt>#</tt> without any preceding
2473 whitespace. All such lines are ignored, even in the middle of
2474 continuation lines for a multiline field, and do not end a
2480 <sect id="binarycontrolfiles">
2481 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2484 The <file>DEBIAN/control</file> file contains the most vital
2485 (and version-dependent) information about a binary package.
2489 The fields in this file are:
2491 <list compact="compact">
2492 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2493 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2494 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2495 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2496 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2497 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2498 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2499 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2500 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2501 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2502 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2503 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2508 <sect id="debiansourcecontrolfiles">
2509 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2512 This file contains a series of fields, identified and
2513 separated just like the fields in the control file of
2514 a binary package. The fields are listed below; their
2515 syntax is described above, in <ref id="pkg-controlfields">.
2517 <list compact="compact">
2518 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2519 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2520 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2522 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2523 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2524 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2525 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2526 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2527 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2528 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2533 The source package control file is generated by
2534 <prgn>dpkg-source</prgn> when it builds the source
2535 archive, from other files in the source package,
2536 described above. When unpacking, it is checked against
2537 the files and directories in the other parts of the
2543 <sect id="debianchangesfiles">
2544 <heading>Debian changes files -- <file>.changes</file></heading>
2547 The .changes files are used by the Debian archive maintenance
2548 software to process updates to packages. They contain one
2549 paragraph which contains information from the
2550 <tt>debian/control</tt> file and other data about the
2551 source package gathered via <tt>debian/changelog</tt>
2552 and <tt>debian/rules</tt>.
2556 The fields in this file are:
2558 <list compact="compact">
2559 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2560 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2561 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2562 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2563 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2564 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2567 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2569 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2570 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2571 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2577 <sect id="controlfieldslist">
2578 <heading>List of fields</heading>
2580 <sect1 id="f-Source">
2581 <heading><tt>Source</tt></heading>
2584 This field identifies the source package name.
2588 In <file>debian/control</file> or a <file>.dsc</file> file,
2589 this field must contain only the name of the source package.
2593 In a binary package control file or a <file>.changes</file>
2594 file, the source package name may be followed by a version
2595 number in parentheses<footnote>
2596 It is customary to leave a space after the package name
2597 if a version number is specified.
2599 This version number may be omitted (and is, by
2600 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2601 the <tt>Version</tt> field of the binary package in
2602 question. The field itself may be omitted from a binary
2603 package control file when the source package has the same
2604 name and version as the binary package.
2608 Package names must consist only of lower case letters
2609 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2610 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2611 They must be at least two characters long and must start
2612 with an alphanumeric character.
2616 <sect1 id="f-Maintainer">
2617 <heading><tt>Maintainer</tt></heading>
2620 The package maintainer's name and email address. The name
2621 should come first, then the email address inside angle
2622 brackets <tt><></tt> (in RFC822 format).
2626 If the maintainer's name contains a full stop then the
2627 whole field will not work directly as an email address due
2628 to a misfeature in the syntax specified in RFC822; a
2629 program using this field as an address must check for this
2630 and correct the problem if necessary (for example by
2631 putting the name in round brackets and moving it to the
2632 end, and bringing the email address forward).
2636 <sect1 id="f-Uploaders">
2637 <heading><tt>Uploaders</tt></heading>
2640 List of the names and email addresses of co-maintainers of
2641 the package, if any. If the package has other maintainers
2642 beside the one named in the
2643 <qref id="f-Maintainer">Maintainer field</qref>, their
2644 names and email addresses should be listed here. The
2645 format is the same as that of the Maintainer tag, and
2646 multiple entries should be comma separated. Currently,
2647 this field is restricted to a single line of data. This
2648 is an optional field.
2651 Any parser that interprets the Uploaders field in
2652 <file>debian/control</file> must permit it to span multiple
2653 lines. Line breaks in an Uploaders field that spans multiple
2654 lines are not significant and the semantics of the field are
2655 the same as if the line breaks had not been present.
2659 <sect1 id="f-Changed-By">
2660 <heading><tt>Changed-By</tt></heading>
2663 The name and email address of the person who changed the
2664 said package. Usually the name of the maintainer.
2665 All the rules for the Maintainer field apply here, too.
2669 <sect1 id="f-Section">
2670 <heading><tt>Section</tt></heading>
2673 This field specifies an application area into which the package
2674 has been classified. See <ref id="subsections">.
2678 When it appears in the <file>debian/control</file> file,
2679 it gives the value for the subfield of the same name in
2680 the <tt>Files</tt> field of the <file>.changes</file> file.
2681 It also gives the default for the same field in the binary
2686 <sect1 id="f-Priority">
2687 <heading><tt>Priority</tt></heading>
2690 This field represents how important that it is that the user
2691 have the package installed. See <ref id="priorities">.
2695 When it appears in the <file>debian/control</file> file,
2696 it gives the value for the subfield of the same name in
2697 the <tt>Files</tt> field of the <file>.changes</file> file.
2698 It also gives the default for the same field in the binary
2703 <sect1 id="f-Package">
2704 <heading><tt>Package</tt></heading>
2707 The name of the binary package.
2711 Package names must consist only of lower case letters
2712 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
2713 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
2714 They must be at least two characters long and must start
2715 with an alphanumeric character.
2719 <sect1 id="f-Architecture">
2720 <heading><tt>Architecture</tt></heading>
2723 Depending on context and the control file used, the
2724 <tt>Architecture</tt> field can include the following sets of
2727 <item>A unique single word identifying a Debian machine
2728 architecture as described in <ref id="arch-spec">.
2729 <item><tt>all</tt>, which indicates an
2730 architecture-independent package.
2731 <item><tt>any</tt>, which indicates a package available
2732 for building on any architecture.
2733 <item><tt>source</tt>, which indicates a source package.
2738 In the main <file>debian/control</file> file in the source
2739 package, this field may contain the special value
2740 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2741 architectures separated by spaces. If <tt>any</tt> or
2742 <tt>all</tt> appear, they must be the entire contents of the
2743 field. Most packages will use either <tt>any</tt> or
2744 <tt>all</tt>. Specifying a specific list of architectures is
2745 for the minority of cases where a program is not portable or
2746 is not useful on some architectures, and where possible the
2747 program should be made portable instead.
2751 In the source package control file <file>.dsc</file>, this
2752 field may contain either the special value <tt>any</tt> or a
2753 list of architectures separated by spaces. If a list is given,
2754 it may include (or consist solely of) the special value
2755 <tt>all</tt>. In other words, in <file>.dsc</file> files
2756 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2757 in combination with specific architectures. The
2758 <tt>Architecture</tt> field in the source package control file
2759 <file>.dsc</file> is generally constructed from the
2760 <tt>Architecture</tt> fields in the
2761 <file>debian/control</file> in the source package.
2765 Specifying <tt>any</tt> indicates that the source package
2766 isn't dependent on any particular architecture and should
2767 compile fine on any one. The produced binary package(s)
2768 will either be specific to whatever the current build
2769 architecture is or will be architecture-independent.
2773 Specifying only <tt>all</tt> indicates that the source package
2774 will only build architecture-independent packages. If this is
2775 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2776 <tt>any</tt> implies that the source package will build at
2777 least one architecture-dependent package.
2781 Specifying a list of architectures indicates that the source
2782 will build an architecture-dependent package, and will only
2783 work correctly on the listed architectures. If the source
2784 package also builds at least one architecture-independent
2785 package, <tt>all</tt> will also be included in the list.
2789 In a <file>.changes</file> file, the <tt>Architecture</tt>
2790 field lists the architecture(s) of the package(s)
2791 currently being uploaded. This will be a list; if the
2792 source for the package is also being uploaded, the special
2793 entry <tt>source</tt> is also present. <tt>all</tt> will be
2794 present if any architecture-independent packages are being
2795 uploaded. <tt>any</tt> may never occur in the
2796 <tt>Architecture</tt> field in the <file>.changes</file>
2801 See <ref id="debianrules"> for information how to get the
2802 architecture for the build process.
2806 <sect1 id="f-Essential">
2807 <heading><tt>Essential</tt></heading>
2810 This is a boolean field which may occur only in the
2811 control file of a binary package or in a per-package fields
2812 paragraph of a main source control data file.
2816 If set to <tt>yes</tt> then the package management system
2817 will refuse to remove the package (upgrading and replacing
2818 it is still possible). The other possible value is <tt>no</tt>,
2819 which is the same as not having the field at all.
2824 <heading>Package interrelationship fields:
2825 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2826 <tt>Recommends</tt>, <tt>Suggests</tt>,
2827 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2828 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2832 These fields describe the package's relationships with
2833 other packages. Their syntax and semantics are described
2834 in <ref id="relationships">.</p>
2837 <sect1 id="f-Standards-Version">
2838 <heading><tt>Standards-Version</tt></heading>
2841 The most recent version of the standards (the policy
2842 manual and associated texts) with which the package
2847 The version number has four components: major and minor
2848 version number and major and minor patch level. When the
2849 standards change in a way that requires every package to
2850 change the major number will be changed. Significant
2851 changes that will require work in many packages will be
2852 signaled by a change to the minor number. The major patch
2853 level will be changed for any change to the meaning of the
2854 standards, however small; the minor patch level will be
2855 changed when only cosmetic, typographical or other edits
2856 are made which neither change the meaning of the document
2857 nor affect the contents of packages.
2861 Thus only the first three components of the policy version
2862 are significant in the <em>Standards-Version</em> control
2863 field, and so either these three components or the all
2864 four components may be specified.<footnote>
2865 In the past, people specified the full version number
2866 in the Standards-Version field, for example "2.3.0.0".
2867 Since minor patch-level changes don't introduce new
2868 policy, it was thought it would be better to relax
2869 policy and only require the first 3 components to be
2870 specified, in this example "2.3.0". All four
2871 components may still be used if someone wishes to do so.
2877 <sect1 id="f-Version">
2878 <heading><tt>Version</tt></heading>
2881 The version number of a package. The format is:
2882 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2886 The three components here are:
2888 <tag><var>epoch</var></tag>
2891 This is a single (generally small) unsigned integer. It
2892 may be omitted, in which case zero is assumed. If it is
2893 omitted then the <var>upstream_version</var> may not
2898 It is provided to allow mistakes in the version numbers
2899 of older versions of a package, and also a package's
2900 previous version numbering schemes, to be left behind.
2904 <tag><var>upstream_version</var></tag>
2907 This is the main part of the version number. It is
2908 usually the version number of the original ("upstream")
2909 package from which the <file>.deb</file> file has been made,
2910 if this is applicable. Usually this will be in the same
2911 format as that specified by the upstream author(s);
2912 however, it may need to be reformatted to fit into the
2913 package management system's format and comparison
2918 The comparison behavior of the package management system
2919 with respect to the <var>upstream_version</var> is
2920 described below. The <var>upstream_version</var>
2921 portion of the version number is mandatory.
2925 The <var>upstream_version</var> may contain only
2926 alphanumerics<footnote>
2927 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2929 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2930 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2931 tilde) and should start with a digit. If there is no
2932 <var>debian_revision</var> then hyphens are not allowed;
2933 if there is no <var>epoch</var> then colons are not
2938 <tag><var>debian_revision</var></tag>
2941 This part of the version number specifies the version of
2942 the Debian package based on the upstream version. It
2943 may contain only alphanumerics and the characters
2944 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2945 tilde) and is compared in the same way as the
2946 <var>upstream_version</var> is.
2950 It is optional; if it isn't present then the
2951 <var>upstream_version</var> may not contain a hyphen.
2952 This format represents the case where a piece of
2953 software was written specifically to be turned into a
2954 Debian package, and so there is only one "debianisation"
2955 of it and therefore no revision indication is required.
2959 It is conventional to restart the
2960 <var>debian_revision</var> at <tt>1</tt> each time the
2961 <var>upstream_version</var> is increased.
2965 The package management system will break the version
2966 number apart at the last hyphen in the string (if there
2967 is one) to determine the <var>upstream_version</var> and
2968 <var>debian_revision</var>. The absence of a
2969 <var>debian_revision</var> is equivalent to a
2970 <var>debian_revision</var> of <tt>0</tt>.
2977 When comparing two version numbers, first the <var>epoch</var>
2978 of each are compared, then the <var>upstream_version</var> if
2979 <var>epoch</var> is equal, and then <var>debian_revision</var>
2980 if <var>upstream_version</var> is also equal.
2981 <var>epoch</var> is compared numerically. The
2982 <var>upstream_version</var> and <var>debian_revision</var>
2983 parts are compared by the package management system using the
2984 following algorithm:
2988 The strings are compared from left to right.
2992 First the initial part of each string consisting entirely of
2993 non-digit characters is determined. These two parts (one of
2994 which may be empty) are compared lexically. If a difference
2995 is found it is returned. The lexical comparison is a
2996 comparison of ASCII values modified so that all the letters
2997 sort earlier than all the non-letters and so that a tilde
2998 sorts before anything, even the end of a part. For example,
2999 the following parts are in sorted order from earliest to
3000 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3001 <tt>a</tt>.<footnote>
3002 One common use of <tt>~</tt> is for upstream pre-releases.
3003 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3004 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3009 Then the initial part of the remainder of each string which
3010 consists entirely of digit characters is determined. The
3011 numerical values of these two parts are compared, and any
3012 difference found is returned as the result of the comparison.
3013 For these purposes an empty string (which can only occur at
3014 the end of one or both version strings being compared) counts
3019 These two steps (comparing and removing initial non-digit
3020 strings and initial digit strings) are repeated until a
3021 difference is found or both strings are exhausted.
3025 Note that the purpose of epochs is to allow us to leave behind
3026 mistakes in version numbering, and to cope with situations
3027 where the version numbering scheme changes. It is
3028 <em>not</em> intended to cope with version numbers containing
3029 strings of letters which the package management system cannot
3030 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3031 silly orderings (the author of this manual has heard of a
3032 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3033 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3034 <tt>2</tt> and so forth).
3038 <sect1 id="f-Description">
3039 <heading><tt>Description</tt></heading>
3042 In a source or binary control file, the <tt>Description</tt>
3043 field contains a description of the binary package, consisting
3044 of two parts, the synopsis or the short description, and the
3045 long description. The field's format is as follows:
3050 Description: <single line synopsis>
3051 <extended description over several lines>
3056 The lines in the extended description can have these formats:
3062 Those starting with a single space are part of a paragraph.
3063 Successive lines of this form will be word-wrapped when
3064 displayed. The leading space will usually be stripped off.
3068 Those starting with two or more spaces. These will be
3069 displayed verbatim. If the display cannot be panned
3070 horizontally, the displaying program will line wrap them "hard"
3071 (i.e., without taking account of word breaks). If it can they
3072 will be allowed to trail off to the right. None, one or two
3073 initial spaces may be deleted, but the number of spaces
3074 deleted from each line will be the same (so that you can have
3075 indenting work correctly, for example).
3079 Those containing a single space followed by a single full stop
3080 character. These are rendered as blank lines. This is the
3081 <em>only</em> way to get a blank line<footnote>
3082 Completely empty lines will not be rendered as blank lines.
3083 Instead, they will cause the parser to think you're starting
3084 a whole new record in the control file, and will therefore
3085 likely abort with an error.
3090 Those containing a space, a full stop and some more characters.
3091 These are for future expansion. Do not use them.
3097 Do not use tab characters. Their effect is not predictable.
3101 See <ref id="descriptions"> for further information on this.
3105 In a <file>.changes</file> file, the <tt>Description</tt> field
3106 contains a summary of the descriptions for the packages being
3111 The part of the field before the first newline is empty;
3112 thereafter each line has the name of a binary package and
3113 the summary description line from that binary package.
3114 Each line is indented by one space.
3119 <sect1 id="f-Distribution">
3120 <heading><tt>Distribution</tt></heading>
3123 In a <file>.changes</file> file or parsed changelog output
3124 this contains the (space-separated) name(s) of the
3125 distribution(s) where this version of the package should
3126 be installed. Valid distributions are determined by the
3127 archive maintainers.<footnote>
3128 Example distribution names in the Debian archive used in
3129 <file>.changes</file> files are:
3130 <taglist compact="compact">
3131 <tag><em>unstable</em></tag>
3133 This distribution value refers to the
3134 <em>developmental</em> part of the Debian distribution
3135 tree. Most new packages, new upstream versions of
3136 packages and bug fixes go into the <em>unstable</em>
3140 <tag><em>experimental</em></tag>
3142 The packages with this distribution value are deemed
3143 by their maintainers to be high risk. Oftentimes they
3144 represent early beta or developmental packages from
3145 various sources that the maintainers want people to
3146 try, but are not ready to be a part of the other parts
3147 of the Debian distribution tree.
3152 Others are used for updating stable releases or for
3153 security uploads. More information is available in the
3154 Debian Developer's Reference, section "The Debian
3158 The Debian archive software only supports listing a single
3159 distribution. Migration of packages to other distributions is
3160 handled outside of the upload process.
3165 <heading><tt>Date</tt></heading>
3168 This field includes the date the package was built or last edited.
3172 The value of this field is usually extracted from the
3173 <file>debian/changelog</file> file - see
3174 <ref id="dpkgchangelog">).
3178 <sect1 id="f-Format">
3179 <heading><tt>Format</tt></heading>
3182 This field specifies a format revision for the file.
3183 The most current format described in the Policy Manual
3184 is version <strong>1.5</strong>. The syntax of the
3185 format value is the same as that of a package version
3186 number except that no epoch or Debian revision is allowed
3187 - see <ref id="f-Version">.
3191 <sect1 id="f-Urgency">
3192 <heading><tt>Urgency</tt></heading>
3195 This is a description of how important it is to upgrade to
3196 this version from previous ones. It consists of a single
3197 keyword taking one of the values <tt>low</tt>,
3198 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3199 <tt>critical</tt><footnote>
3200 Other urgency values are supported with configuration
3201 changes in the archive software but are not used in Debian.
3202 The urgency affects how quickly a package will be considered
3203 for inclusion into the <tt>testing</tt> distribution and
3204 gives an indication of the importance of any fixes included
3205 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3206 treated as synonymous.
3207 </footnote> (not case-sensitive) followed by an optional
3208 commentary (separated by a space) which is usually in
3209 parentheses. For example:
3212 Urgency: low (HIGH for users of diversions)
3218 The value of this field is usually extracted from the
3219 <file>debian/changelog</file> file - see
3220 <ref id="dpkgchangelog">.
3224 <sect1 id="f-Changes">
3225 <heading><tt>Changes</tt></heading>
3228 This field contains the human-readable changes data, describing
3229 the differences between the last version and the current one.
3233 There should be nothing in this field before the first
3234 newline; all the subsequent lines must be indented by at
3235 least one space; blank lines must be represented by a line
3236 consisting only of a space and a full stop.
3240 The value of this field is usually extracted from the
3241 <file>debian/changelog</file> file - see
3242 <ref id="dpkgchangelog">).
3246 Each version's change information should be preceded by a
3247 "title" line giving at least the version, distribution(s)
3248 and urgency, in a human-readable way.
3252 If data from several versions is being returned the entry
3253 for the most recent version should be returned first, and
3254 entries should be separated by the representation of a
3255 blank line (the "title" line may also be followed by the
3256 representation of blank line).
3260 <sect1 id="f-Binary">
3261 <heading><tt>Binary</tt></heading>
3264 This field is a list of binary packages.
3268 When it appears in the <file>.dsc</file> file it is the list
3269 of binary packages which a source package can produce. It
3270 does not necessarily produce all of these binary packages
3271 for every architecture. The source control file doesn't
3272 contain details of which architectures are appropriate for
3273 which of the binary packages.
3277 When it appears in a <file>.changes</file> file it lists the
3278 names of the binary packages actually being uploaded.
3282 The syntax is a list of binary packages separated by
3284 A space after each comma is conventional.
3285 </footnote>. Currently the packages must be separated using
3286 only spaces in the <file>.changes</file> file.
3290 <sect1 id="f-Installed-Size">
3291 <heading><tt>Installed-Size</tt></heading>
3294 This field appears in the control files of binary packages,
3295 and in the <file>Packages</file> files. It gives an
3296 estimation the total amount of disk space required to install
3297 the named package. Actual installed size may vary based on
3298 block size, file system properties, or actions taken by
3299 package maintainer scripts.
3303 The disk space is given as the integer value of the estimated
3304 installed size in bytes, divided by 1024 and rounded up.
3308 <sect1 id="f-Files">
3309 <heading><tt>Files</tt></heading>
3312 This field contains a list of files with information about
3313 each one. The exact information and syntax varies with
3314 the context. In all cases the part of the field
3315 contents on the same line as the field name is empty. The
3316 remainder of the field is one line per file, each line
3317 being indented by one space and containing a number of
3318 sub-fields separated by spaces.
3322 In the <file>.dsc</file> file, each line contains the MD5
3323 checksum, size and filename of the tar file and (if applicable)
3324 diff file which make up the remainder of the source
3326 That is, the parts which are not the <tt>.dsc</tt>.
3328 The exact forms of the filenames are described
3329 in <ref id="pkg-sourcearchives">.
3333 In the <file>.changes</file> file this contains one line per
3334 file being uploaded. Each line contains the MD5 checksum,
3335 size, section and priority and the filename.
3336 The <qref id="f-Section">section</qref>
3337 and <qref id="f-Priority">priority</qref>
3338 are the values of the corresponding fields in
3339 the main source control file. If no section or priority is
3340 specified then <tt>-</tt> should be used, though section
3341 and priority values must be specified for new packages to
3342 be installed properly.
3346 The special value <tt>byhand</tt> for the section in a
3347 <tt>.changes</tt> file indicates that the file in question
3348 is not an ordinary package file and must by installed by
3349 hand by the distribution maintainers. If the section is
3350 <tt>byhand</tt> the priority should be <tt>-</tt>.
3354 If a new Debian revision of a package is being shipped and
3355 no new original source archive is being distributed the
3356 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3357 entry for the original source archive
3358 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3359 but the <file>.changes</file> file should leave it out. In
3360 this case the original source archive on the distribution
3361 site must match exactly, byte-for-byte, the original
3362 source archive which was used to generate the
3363 <file>.dsc</file> file and diff which are being uploaded.</p>
3366 <sect1 id="f-Closes">
3367 <heading><tt>Closes</tt></heading>
3370 A space-separated list of bug report numbers that the upload
3371 governed by the .changes file closes.
3375 <sect1 id="f-Homepage">
3376 <heading><tt>Homepage</tt></heading>
3379 The URL of the web site for this package, preferably (when
3380 applicable) the site from which the original source can be
3381 obtained and any additional upstream documentation or
3382 information may be found. The content of this field is a
3383 simple URL without any surrounding characters such as
3391 <heading>User-defined fields</heading>
3394 Additional user-defined fields may be added to the
3395 source package control file. Such fields will be
3396 ignored, and not copied to (for example) binary or
3397 source package control files or upload control files.
3401 If you wish to add additional unsupported fields to
3402 these output files you should use the mechanism
3407 Fields in the main source control information file with
3408 names starting <tt>X</tt>, followed by one or more of
3409 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3410 be copied to the output files. Only the part of the
3411 field name after the hyphen will be used in the output
3412 file. Where the letter <tt>B</tt> is used the field
3413 will appear in binary package control files, where the
3414 letter <tt>S</tt> is used in source package control
3415 files and where <tt>C</tt> is used in upload control
3416 (<tt>.changes</tt>) files.
3420 For example, if the main source information control file
3423 XBS-Comment: I stand between the candle and the star.
3425 then the binary and source package control files will contain the
3428 Comment: I stand between the candle and the star.
3437 <chapt id="maintainerscripts">
3438 <heading>Package maintainer scripts and installation procedure</heading>
3441 <heading>Introduction to package maintainer scripts</heading>
3444 It is possible to supply scripts as part of a package which
3445 the package management system will run for you when your
3446 package is installed, upgraded or removed.
3450 These scripts are the files <prgn>preinst</prgn>,
3451 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3452 <prgn>postrm</prgn> in the control area of the package.
3453 They must be proper executable files; if they are scripts
3454 (which is recommended), they must start with the usual
3455 <tt>#!</tt> convention. They should be readable and
3456 executable by anyone, and must not be world-writable.
3460 The package management system looks at the exit status from
3461 these scripts. It is important that they exit with a
3462 non-zero status if there is an error, so that the package
3463 management system can stop its processing. For shell
3464 scripts this means that you <em>almost always</em> need to
3465 use <tt>set -e</tt> (this is usually true when writing shell
3466 scripts, in fact). It is also important, of course, that
3467 they exit with a zero status if everything went well.
3471 Additionally, packages interacting with users using
3472 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3473 install a <prgn>config</prgn> script in the control area,
3474 see <ref id="maintscriptprompt"> for details.
3478 When a package is upgraded a combination of the scripts from
3479 the old and new packages is called during the upgrade
3480 procedure. If your scripts are going to be at all
3481 complicated you need to be aware of this, and may need to
3482 check the arguments to your scripts.
3486 Broadly speaking the <prgn>preinst</prgn> is called before
3487 (a particular version of) a package is installed, and the
3488 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3489 before (a version of) a package is removed and the
3490 <prgn>postrm</prgn> afterwards.
3494 Programs called from maintainer scripts should not normally
3495 have a path prepended to them. Before installation is
3496 started, the package management system checks to see if the
3497 programs <prgn>ldconfig</prgn>,
3498 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3499 and <prgn>update-rc.d</prgn> can be found via the
3500 <tt>PATH</tt> environment variable. Those programs, and any
3501 other program that one would expect to be in the
3502 <tt>PATH</tt>, should thus be invoked without an absolute
3503 pathname. Maintainer scripts should also not reset the
3504 <tt>PATH</tt>, though they might choose to modify it by
3505 prepending or appending package-specific directories. These
3506 considerations really apply to all shell scripts.</p>
3509 <sect id="idempotency">
3510 <heading>Maintainer scripts idempotency</heading>
3513 It is necessary for the error recovery procedures that the
3514 scripts be idempotent. This means that if it is run
3515 successfully, and then it is called again, it doesn't bomb
3516 out or cause any harm, but just ensures that everything is
3517 the way it ought to be. If the first call failed, or
3518 aborted half way through for some reason, the second call
3519 should merely do the things that were left undone the first
3520 time, if any, and exit with a success status if everything
3522 This is so that if an error occurs, the user interrupts
3523 <prgn>dpkg</prgn> or some other unforeseen circumstance
3524 happens you don't leave the user with a badly-broken
3525 package when <prgn>dpkg</prgn> attempts to repeat the
3531 <sect id="controllingterminal">
3532 <heading>Controlling terminal for maintainer scripts</heading>
3535 The maintainer scripts are guaranteed to run with a
3536 controlling terminal and can interact with the user.
3537 Because these scripts may be executed with standard output
3538 redirected into a pipe for logging purposes, Perl scripts
3539 should set unbuffered output by setting <tt>$|=1</tt> so
3540 that the output is printed immediately rather than being
3544 <sect id="exitstatus">
3545 <heading>Exit status</heading>
3548 Each script must return a zero exit status for
3549 success, or a nonzero one for failure, since the package
3550 management system looks for the exit status of these scripts
3551 and determines what action to take next based on that datum.
3555 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3560 <list compact="compact">
3562 <var>new-preinst</var> <tt>install</tt>
3565 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3568 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3571 <var>old-preinst</var> <tt>abort-upgrade</tt>
3572 <var>new-version</var>
3577 <list compact="compact">
3579 <var>postinst</var> <tt>configure</tt>
3580 <var>most-recently-configured-version</var>
3583 <var>old-postinst</var> <tt>abort-upgrade</tt>
3584 <var>new-version</var>
3587 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3588 <tt>in-favour</tt> <var>package</var>
3589 <var>new-version</var>
3592 <var>postinst</var> <tt>abort-remove</tt>
3595 <var>deconfigured's-postinst</var>
3596 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3597 <var>failed-install-package</var> <var>version</var>
3598 [<tt>removing</tt> <var>conflicting-package</var>
3604 <list compact="compact">
3606 <var>prerm</var> <tt>remove</tt>
3609 <var>old-prerm</var> <tt>upgrade</tt>
3610 <var>new-version</var>
3613 <var>new-prerm</var> <tt>failed-upgrade</tt>
3614 <var>old-version</var>
3617 <var>conflictor's-prerm</var> <tt>remove</tt>
3618 <tt>in-favour</tt> <var>package</var>
3619 <var>new-version</var>
3622 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3623 <tt>in-favour</tt> <var>package-being-installed</var>
3624 <var>version</var> [<tt>removing</tt>
3625 <var>conflicting-package</var>
3631 <list compact="compact">
3633 <var>postrm</var> <tt>remove</tt>
3636 <var>postrm</var> <tt>purge</tt>
3639 <var>old-postrm</var> <tt>upgrade</tt>
3640 <var>new-version</var>
3643 <var>new-postrm</var> <tt>failed-upgrade</tt>
3644 <var>old-version</var>
3647 <var>new-postrm</var> <tt>abort-install</tt>
3650 <var>new-postrm</var> <tt>abort-install</tt>
3651 <var>old-version</var>
3654 <var>new-postrm</var> <tt>abort-upgrade</tt>
3655 <var>old-version</var>
3658 <var>disappearer's-postrm</var> <tt>disappear</tt>
3659 <var>overwriter</var>
3660 <var>overwriter-version</var>
3666 <sect id="unpackphase">
3667 <heading>Details of unpack phase of installation or upgrade</heading>
3670 The procedure on installation/upgrade/overwrite/disappear
3671 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3672 stage of <tt>dpkg --install</tt>) is as follows. In each
3673 case, if a major error occurs (unless listed below) the
3674 actions are, in general, run backwards - this means that the
3675 maintainer scripts are run with different arguments in
3676 reverse order. These are the "error unwind" calls listed
3683 If a version of the package is already installed, call
3684 <example compact="compact">
3685 <var>old-prerm</var> upgrade <var>new-version</var>
3689 If the script runs but exits with a non-zero
3690 exit status, <prgn>dpkg</prgn> will attempt:
3691 <example compact="compact">
3692 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3694 If this works, the upgrade continues. If this
3695 does not work, the error unwind:
3696 <example compact="compact">
3697 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3699 If this works, then the old-version is
3700 "Installed", if not, the old version is in a
3701 "Failed-Config" state.
3707 If a "conflicting" package is being removed at the same time,
3708 or if any package will be broken (due to <tt>Breaks</tt>):
3711 If <tt>--auto-deconfigure</tt> is
3712 specified, call, for each package to be deconfigured
3713 due to <tt>Breaks</tt>:
3714 <example compact="compact">
3715 <var>deconfigured's-prerm</var> deconfigure \
3716 in-favour <var>package-being-installed</var> <var>version</var>
3719 <example compact="compact">
3720 <var>deconfigured's-postinst</var> abort-deconfigure \
3721 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3723 The deconfigured packages are marked as
3724 requiring configuration, so that if
3725 <tt>--install</tt> is used they will be
3726 configured again if possible.
3729 If any packages depended on a conflicting
3730 package being removed and <tt>--auto-deconfigure</tt> is
3731 specified, call, for each such package:
3732 <example compact="compact">
3733 <var>deconfigured's-prerm</var> deconfigure \
3734 in-favour <var>package-being-installed</var> <var>version</var> \
3735 removing <var>conflicting-package</var> <var>version</var>
3738 <example compact="compact">
3739 <var>deconfigured's-postinst</var> abort-deconfigure \
3740 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3741 removing <var>conflicting-package</var> <var>version</var>
3743 The deconfigured packages are marked as
3744 requiring configuration, so that if
3745 <tt>--install</tt> is used they will be
3746 configured again if possible.
3749 To prepare for removal of each conflicting package, call:
3750 <example compact="compact">
3751 <var>conflictor's-prerm</var> remove \
3752 in-favour <var>package</var> <var>new-version</var>
3755 <example compact="compact">
3756 <var>conflictor's-postinst</var> abort-remove \
3757 in-favour <var>package</var> <var>new-version</var>
3766 If the package is being upgraded, call:
3767 <example compact="compact">
3768 <var>new-preinst</var> upgrade <var>old-version</var>
3770 If this fails, we call:
3772 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3779 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3781 is called. If this works, then the old version
3782 is in an "Installed" state, or else it is left
3783 in an "Unpacked" state.
3788 If it fails, then the old version is left
3789 in an "Half-Installed" state.
3796 Otherwise, if the package had some configuration
3797 files from a previous version installed (i.e., it
3798 is in the "configuration files only" state):
3799 <example compact="compact">
3800 <var>new-preinst</var> install <var>old-version</var>
3804 <var>new-postrm</var> abort-install <var>old-version</var>
3806 If this fails, the package is left in a
3807 "Half-Installed" state, which requires a
3808 reinstall. If it works, the packages is left in
3809 a "Config Files" state.
3812 Otherwise (i.e., the package was completely purged):
3813 <example compact="compact">
3814 <var>new-preinst</var> install
3817 <example compact="compact">
3818 <var>new-postrm</var> abort-install
3820 If the error-unwind fails, the package is in a
3821 "Half Installed" phase, and requires a
3822 reinstall. If the error unwind works, the
3823 package is in a not installed state.
3830 The new package's files are unpacked, overwriting any
3831 that may be on the system already, for example any
3832 from the old version of the same package or from
3833 another package. Backups of the old files are kept
3834 temporarily, and if anything goes wrong the package
3835 management system will attempt to put them back as
3836 part of the error unwind.
3840 It is an error for a package to contain files which
3841 are on the system in another package, unless
3842 <tt>Replaces</tt> is used (see <ref id="replaces">).
3844 The following paragraph is not currently the case:
3845 Currently the <tt>- - force-overwrite</tt> flag is
3846 enabled, downgrading it to a warning, but this may not
3852 It is a more serious error for a package to contain a
3853 plain file or other kind of non-directory where another
3854 package has a directory (again, unless
3855 <tt>Replaces</tt> is used). This error can be
3856 overridden if desired using
3857 <tt>--force-overwrite-dir</tt>, but this is not
3862 Packages which overwrite each other's files produce
3863 behavior which, though deterministic, is hard for the
3864 system administrator to understand. It can easily
3865 lead to "missing" programs if, for example, a package
3866 is installed which overwrites a file from another
3867 package, and is then removed again.<footnote>
3868 Part of the problem is due to what is arguably a
3869 bug in <prgn>dpkg</prgn>.
3874 A directory will never be replaced by a symbolic link
3875 to a directory or vice versa; instead, the existing
3876 state (symlink or not) will be left alone and
3877 <prgn>dpkg</prgn> will follow the symlink if there is
3886 If the package is being upgraded, call
3887 <example compact="compact">
3888 <var>old-postrm</var> upgrade <var>new-version</var>
3892 If this fails, <prgn>dpkg</prgn> will attempt:
3893 <example compact="compact">
3894 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3896 If this works, installation continues. If not,
3898 <example compact="compact">
3899 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3901 If this fails, the old version is left in an
3902 "Half Installed" state. If it works, dpkg now
3904 <example compact="compact">
3905 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3907 If this fails, the old version is left in an
3908 "Half Installed" state. If it works, dpkg now
3910 <example compact="compact">
3911 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3913 If this fails, the old version is in an
3920 This is the point of no return - if
3921 <prgn>dpkg</prgn> gets this far, it won't back off
3922 past this point if an error occurs. This will
3923 leave the package in a fairly bad state, which
3924 will require a successful re-installation to clear
3925 up, but it's when <prgn>dpkg</prgn> starts doing
3926 things that are irreversible.
3931 Any files which were in the old version of the package
3932 but not in the new are removed.
3936 The new file list replaces the old.
3940 The new maintainer scripts replace the old.
3944 Any packages all of whose files have been overwritten
3945 during the installation, and which aren't required for
3946 dependencies, are considered to have been removed.
3947 For each such package
3950 <prgn>dpkg</prgn> calls:
3951 <example compact="compact">
3952 <var>disappearer's-postrm</var> disappear \
3953 <var>overwriter</var> <var>overwriter-version</var>
3957 The package's maintainer scripts are removed.
3960 It is noted in the status database as being in a
3961 sane state, namely not installed (any conffiles
3962 it may have are ignored, rather than being
3963 removed by <prgn>dpkg</prgn>). Note that
3964 disappearing packages do not have their prerm
3965 called, because <prgn>dpkg</prgn> doesn't know
3966 in advance that the package is going to
3973 Any files in the package we're unpacking that are also
3974 listed in the file lists of other packages are removed
3975 from those lists. (This will lobotomize the file list
3976 of the "conflicting" package if there is one.)
3980 The backup files made during installation, above, are
3986 The new package's status is now sane, and recorded as
3991 Here is another point of no return - if the
3992 conflicting package's removal fails we do not unwind
3993 the rest of the installation; the conflicting package
3994 is left in a half-removed limbo.
3999 If there was a conflicting package we go and do the
4000 removal actions (described below), starting with the
4001 removal of the conflicting package's files (any that
4002 are also in the package being installed have already
4003 been removed from the conflicting package's file list,
4004 and so do not get removed now).
4010 <sect id="configdetails"><heading>Details of configuration</heading>
4013 When we configure a package (this happens with <tt>dpkg
4014 --install</tt> and <tt>dpkg --configure</tt>), we first
4015 update any <tt>conffile</tt>s and then call:
4016 <example compact="compact">
4017 <var>postinst</var> configure <var>most-recently-configured-version</var>
4022 No attempt is made to unwind after errors during
4023 configuration. If the configuration fails, the package is in
4024 a "Failed Config" state, and an error message is generated.
4028 If there is no most recently configured version
4029 <prgn>dpkg</prgn> will pass a null argument.
4032 Historical note: Truly ancient (pre-1997) versions of
4033 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4034 (including the angle brackets) in this case. Even older
4035 ones did not pass a second argument at all, under any
4036 circumstance. Note that upgrades using such an old dpkg
4037 version are unlikely to work for other reasons, even if
4038 this old argument behavior is handled by your postinst script.
4044 <sect id="removedetails"><heading>Details of removal and/or
4045 configuration purging</heading>
4051 <example compact="compact">
4052 <var>prerm</var> remove
4056 If prerm fails during replacement due to conflict
4058 <var>conflictor's-postinst</var> abort-remove \
4059 in-favour <var>package</var> <var>new-version</var>
4063 <var>postinst</var> abort-remove
4067 If this fails, the package is in a "Failed-Config"
4068 state, or else it remains "Installed".
4072 The package's files are removed (except <tt>conffile</tt>s).
4075 <example compact="compact">
4076 <var>postrm</var> remove
4080 If it fails, there's no error unwind, and the package is in
4081 an "Half-Installed" state.
4086 All the maintainer scripts except the <prgn>postrm</prgn>
4091 If we aren't purging the package we stop here. Note
4092 that packages which have no <prgn>postrm</prgn> and no
4093 <tt>conffile</tt>s are automatically purged when
4094 removed, as there is no difference except for the
4095 <prgn>dpkg</prgn> status.
4099 The <tt>conffile</tt>s and any backup files
4100 (<tt>~</tt>-files, <tt>#*#</tt> files,
4101 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4106 <example compact="compact">
4107 <var>postrm</var> purge
4111 If this fails, the package remains in a "Config-Files"
4116 The package's file list is removed.
4125 <chapt id="relationships">
4126 <heading>Declaring relationships between packages</heading>
4128 <sect id="depsyntax">
4129 <heading>Syntax of relationship fields</heading>
4132 These fields all have a uniform syntax. They are a list of
4133 package names separated by commas.
4137 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4138 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4139 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4140 control file fields of the package, which declare
4141 dependencies on other packages, the package names listed may
4142 also include lists of alternative package names, separated
4143 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4144 if any one of the alternative packages is installed, that
4145 part of the dependency is considered to be satisfied.
4149 All of the fields except for <tt>Provides</tt> may restrict
4150 their applicability to particular versions of each named
4151 package. This is done in parentheses after each individual
4152 package name; the parentheses should contain a relation from
4153 the list below followed by a version number, in the format
4154 described in <ref id="f-Version">.
4158 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4159 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4160 strictly earlier, earlier or equal, exactly equal, later or
4161 equal and strictly later, respectively. The deprecated
4162 forms <tt><</tt> and <tt>></tt> were used to mean
4163 earlier/later or equal, rather than strictly earlier/later,
4164 so they should not appear in new packages (though
4165 <prgn>dpkg</prgn> still supports them).
4169 Whitespace may appear at any point in the version
4170 specification subject to the rules in <ref
4171 id="controlsyntax">, and must appear where it's necessary to
4172 disambiguate; it is not otherwise significant. All of the
4173 relationship fields may span multiple lines. For
4174 consistency and in case of future changes to
4175 <prgn>dpkg</prgn> it is recommended that a single space be
4176 used after a version relationship and before a version
4177 number; it is also conventional to put a single space after
4178 each comma, on either side of each vertical bar, and before
4179 each open parenthesis. When wrapping a relationship field, it
4180 is conventional to do so after a comma and before the space
4181 following that comma.
4185 For example, a list of dependencies might appear as:
4186 <example compact="compact">
4189 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4194 All fields that specify build-time relationships
4195 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4196 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4197 may be restricted to a certain set of architectures. This
4198 is indicated in brackets after each individual package name and
4199 the optional version specification. The brackets enclose a
4200 list of Debian architecture names separated by whitespace.
4201 Exclamation marks may be prepended to each of the names.
4202 (It is not permitted for some names to be prepended with
4203 exclamation marks while others aren't.) If the current Debian
4204 host architecture is not in this list and there are no
4205 exclamation marks in the list, or it is in the list with a
4206 prepended exclamation mark, the package name and the
4207 associated version specification are ignored completely for
4208 the purposes of defining the relationships.
4213 <example compact="compact">
4215 Build-Depends-Indep: texinfo
4216 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4217 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4219 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4220 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4221 <tt>gnumach-dev</tt> only on hurd-i386.
4225 If the architecture-restricted dependency is part of a set of
4226 alternatives using <tt>|</tt>, that alternative is ignored
4227 completely on architectures that do not match the restriction.
4229 <example compact="compact">
4230 Build-Depends: foo [!i386] | bar [!amd64]
4232 is equivalent to <tt>bar</tt> on the i386 architecture, to
4233 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4234 bar</tt> on all other architectures.
4238 Note that the binary package relationship fields such as
4239 <tt>Depends</tt> appear in one of the binary package
4240 sections of the control file, whereas the build-time
4241 relationships such as <tt>Build-Depends</tt> appear in the
4242 source package section of the control file (which is the
4247 <sect id="binarydeps">
4248 <heading>Binary Dependencies - <tt>Depends</tt>,
4249 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4250 <tt>Pre-Depends</tt>
4254 Packages can declare in their control file that they have
4255 certain relationships to other packages - for example, that
4256 they may not be installed at the same time as certain other
4257 packages, and/or that they depend on the presence of others.
4261 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4262 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4263 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4264 <tt>Breaks</tt> is described in <ref id="breaks">, and
4265 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4266 rest are described below.
4270 These seven fields are used to declare a dependency
4271 relationship by one package on another. Except for
4272 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4273 depending (binary) package's control file.
4274 (<tt>Enhances</tt> appears in the recommending package's
4275 control file, and <tt>Breaks</tt> appears in the version of
4276 depended-on package which causes the named package to
4281 A <tt>Depends</tt> field takes effect <em>only</em> when a
4282 package is to be configured. It does not prevent a package
4283 being on the system in an unconfigured state while its
4284 dependencies are unsatisfied, and it is possible to replace
4285 a package whose dependencies are satisfied and which is
4286 properly installed with a different version whose
4287 dependencies are not and cannot be satisfied; when this is
4288 done the depending package will be left unconfigured (since
4289 attempts to configure it will give errors) and will not
4290 function properly. If it is necessary, a
4291 <tt>Pre-Depends</tt> field can be used, which has a partial
4292 effect even when a package is being unpacked, as explained
4293 in detail below. (The other three dependency fields,
4294 <tt>Recommends</tt>, <tt>Suggests</tt> and
4295 <tt>Enhances</tt>, are only used by the various front-ends
4296 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4297 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4301 For this reason packages in an installation run are usually
4302 all unpacked first and all configured later; this gives
4303 later versions of packages with dependencies on later
4304 versions of other packages the opportunity to have their
4305 dependencies satisfied.
4309 In case of circular dependencies, since installation or
4310 removal order honoring the dependency order can't be
4311 established, dependency loops are broken at some point
4312 (based on rules below), and some packages may not be able to
4313 rely on their dependencies being present when being
4314 installed or removed, depending on which side of the break
4315 of the circular dependency loop they happen to be on. If one
4316 of the packages in the loop has no postinst script, then the
4317 cycle will be broken at that package, so as to ensure that
4318 all postinst scripts run with the dependencies properly
4319 configured if this is possible. Otherwise the breaking point
4324 The <tt>Depends</tt> field thus allows package maintainers
4325 to impose an order in which packages should be configured.
4329 The meaning of the five dependency fields is as follows:
4331 <tag><tt>Depends</tt></tag>
4334 This declares an absolute dependency. A package will
4335 not be configured unless all of the packages listed in
4336 its <tt>Depends</tt> field have been correctly
4341 The <tt>Depends</tt> field should be used if the
4342 depended-on package is required for the depending
4343 package to provide a significant amount of
4348 The <tt>Depends</tt> field should also be used if the
4349 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4350 <prgn>postrm</prgn> scripts require the package to be
4351 present in order to run. Note, however, that the
4352 <prgn>postrm</prgn> cannot rely on any non-essential
4353 packages to be present during the <tt>purge</tt>
4357 <tag><tt>Recommends</tt></tag>
4360 This declares a strong, but not absolute, dependency.
4364 The <tt>Recommends</tt> field should list packages
4365 that would be found together with this one in all but
4366 unusual installations.
4370 <tag><tt>Suggests</tt></tag>
4372 This is used to declare that one package may be more
4373 useful with one or more others. Using this field
4374 tells the packaging system and the user that the
4375 listed packages are related to this one and can
4376 perhaps enhance its usefulness, but that installing
4377 this one without them is perfectly reasonable.
4380 <tag><tt>Enhances</tt></tag>
4382 This field is similar to Suggests but works in the
4383 opposite direction. It is used to declare that a
4384 package can enhance the functionality of another
4388 <tag><tt>Pre-Depends</tt></tag>
4391 This field is like <tt>Depends</tt>, except that it
4392 also forces <prgn>dpkg</prgn> to complete installation
4393 of the packages named before even starting the
4394 installation of the package which declares the
4395 pre-dependency, as follows:
4399 When a package declaring a pre-dependency is about to
4400 be <em>unpacked</em> the pre-dependency can be
4401 satisfied if the depended-on package is either fully
4402 configured, <em>or even if</em> the depended-on
4403 package(s) are only unpacked or half-configured,
4404 provided that they have been configured correctly at
4405 some point in the past (and not removed or partially
4406 removed since). In this case, both the
4407 previously-configured and currently unpacked or
4408 half-configured versions must satisfy any version
4409 clause in the <tt>Pre-Depends</tt> field.
4413 When the package declaring a pre-dependency is about
4414 to be <em>configured</em>, the pre-dependency will be
4415 treated as a normal <tt>Depends</tt>, that is, it will
4416 be considered satisfied only if the depended-on
4417 package has been correctly configured.
4421 <tt>Pre-Depends</tt> should be used sparingly,
4422 preferably only by packages whose premature upgrade or
4423 installation would hamper the ability of the system to
4424 continue with any upgrade that might be in progress.
4428 <tt>Pre-Depends</tt> are also required if the
4429 <prgn>preinst</prgn> script depends on the named
4430 package. It is best to avoid this situation if
4438 When selecting which level of dependency to use you should
4439 consider how important the depended-on package is to the
4440 functionality of the one declaring the dependency. Some
4441 packages are composed of components of varying degrees of
4442 importance. Such a package should list using
4443 <tt>Depends</tt> the package(s) which are required by the
4444 more important components. The other components'
4445 requirements may be mentioned as Suggestions or
4446 Recommendations, as appropriate to the components' relative
4452 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4455 When one binary package declares that it breaks another,
4456 <prgn>dpkg</prgn> will refuse to allow the package which
4457 declares <tt>Breaks</tt> be installed unless the broken
4458 package is deconfigured first, and it will refuse to
4459 allow the broken package to be reconfigured.
4463 A package will not be regarded as causing breakage merely
4464 because its configuration files are still installed; it must
4465 be at least half-installed.
4469 A special exception is made for packages which declare that
4470 they break their own package name or a virtual package which
4471 they provide (see below): this does not count as a real
4476 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4477 version clause; such a <tt>Breaks</tt> is introduced in the
4478 version of an (implicit or explicit) dependency which
4479 violates an assumption or reveals a bug in earlier versions
4480 of the broken package. This use of <tt>Breaks</tt> will
4481 inform higher-level package management tools that broken
4482 package must be upgraded before the new one.
4486 If the breaking package also overwrites some files from the
4487 older package, it should use <tt>Replaces</tt> (not
4488 <tt>Conflicts</tt>) to ensure this goes smoothly.
4492 <sect id="conflicts">
4493 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4496 When one binary package declares a conflict with another
4497 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4498 refuse to allow them to be installed on the system at the
4503 If one package is to be installed, the other must be removed
4504 first - if the package being installed is marked as
4505 replacing (see <ref id="replaces">) the one on the system,
4506 or the one on the system is marked as deselected, or both
4507 packages are marked <tt>Essential</tt>, then
4508 <prgn>dpkg</prgn> will automatically remove the package
4509 which is causing the conflict, otherwise it will halt the
4510 installation of the new package with an error. This
4511 mechanism is specifically designed to produce an error when
4512 the installed package is <tt>Essential</tt>, but the new
4517 A package will not cause a conflict merely because its
4518 configuration files are still installed; it must be at least
4523 A special exception is made for packages which declare a
4524 conflict with their own package name, or with a virtual
4525 package which they provide (see below): this does not
4526 prevent their installation, and allows a package to conflict
4527 with others providing a replacement for it. You use this
4528 feature when you want the package in question to be the only
4529 package providing some feature.
4533 A <tt>Conflicts</tt> entry should almost never have an
4534 "earlier than" version clause. This would prevent
4535 <prgn>dpkg</prgn> from upgrading or installing the package
4536 which declared such a conflict until the upgrade or removal
4537 of the conflicted-with package had been completed. Instead,
4538 <tt>Breaks</tt> may be used.
4542 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4546 As well as the names of actual ("concrete") packages, the
4547 package relationship fields <tt>Depends</tt>,
4548 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4549 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4550 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4551 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4552 may mention "virtual packages".
4556 A <em>virtual package</em> is one which appears in the
4557 <tt>Provides</tt> control file field of another package.
4558 The effect is as if the package(s) which provide a
4559 particular virtual package name had been listed by name
4560 everywhere the virtual package name appears. (See also <ref
4565 If there are both concrete and virtual packages of the same
4566 name, then the dependency may be satisfied (or the conflict
4567 caused) by either the concrete package with the name in
4568 question or any other concrete package which provides the
4569 virtual package with the name in question. This is so that,
4570 for example, supposing we have
4571 <example compact="compact">
4574 </example> and someone else releases an enhanced version of
4575 the <tt>bar</tt> package they can say:
4576 <example compact="compact">
4580 and the <tt>bar-plus</tt> package will now also satisfy the
4581 dependency for the <tt>foo</tt> package.
4585 If a relationship field has a version number attached
4586 then only real packages will be considered to see whether
4587 the relationship is satisfied (or the prohibition violated,
4588 for a conflict or breakage) - it is assumed that a real
4589 package which provides the virtual package is not of the
4590 "right" version. So, a <tt>Provides</tt> field may not
4591 contain version numbers, and the version number of the
4592 concrete package which provides a particular virtual package
4593 will not be looked at when considering a dependency on or
4594 conflict with the virtual package name.
4598 It is likely that the ability will be added in a future
4599 release of <prgn>dpkg</prgn> to specify a version number for
4600 each virtual package it provides. This feature is not yet
4601 present, however, and is expected to be used only
4606 If you want to specify which of a set of real packages
4607 should be the default to satisfy a particular dependency on
4608 a virtual package, you should list the real package as an
4609 alternative before the virtual one.
4614 <sect id="replaces"><heading>Overwriting files and replacing
4615 packages - <tt>Replaces</tt></heading>
4618 Packages can declare in their control file that they should
4619 overwrite files in certain other packages, or completely
4620 replace other packages. The <tt>Replaces</tt> control file
4621 field has these two distinct purposes.
4624 <sect1><heading>Overwriting files in other packages</heading>
4627 Firstly, as mentioned before, it is usually an error for a
4628 package to contain files which are on the system in
4633 However, if the overwriting package declares that it
4634 <tt>Replaces</tt> the one containing the file being
4635 overwritten, then <prgn>dpkg</prgn> will replace the file
4636 from the old package with that from the new. The file
4637 will no longer be listed as "owned" by the old package.
4641 If a package is completely replaced in this way, so that
4642 <prgn>dpkg</prgn> does not know of any files it still
4643 contains, it is considered to have "disappeared". It will
4644 be marked as not wanted on the system (selected for
4645 removal) and not installed. Any <tt>conffile</tt>s
4646 details noted for the package will be ignored, as they
4647 will have been taken over by the overwriting package. The
4648 package's <prgn>postrm</prgn> script will be run with a
4649 special argument to allow the package to do any final
4650 cleanup required. See <ref id="mscriptsinstact">.
4653 Replaces is a one way relationship -- you have to
4654 install the replacing package after the replaced
4661 For this usage of <tt>Replaces</tt>, virtual packages (see
4662 <ref id="virtual">) are not considered when looking at a
4663 <tt>Replaces</tt> field - the packages declared as being
4664 replaced must be mentioned by their real names.
4668 Furthermore, this usage of <tt>Replaces</tt> only takes
4669 effect when both packages are at least partially on the
4670 system at once, so that it can only happen if they do not
4671 conflict or if the conflict has been overridden.
4676 <sect1><heading>Replacing whole packages, forcing their
4680 Secondly, <tt>Replaces</tt> allows the packaging system to
4681 resolve which package should be removed when there is a
4682 conflict - see <ref id="conflicts">. This usage only
4683 takes effect when the two packages <em>do</em> conflict,
4684 so that the two usages of this field do not interfere with
4689 In this situation, the package declared as being replaced
4690 can be a virtual package, so for example, all mail
4691 transport agents (MTAs) would have the following fields in
4692 their control files:
4693 <example compact="compact">
4694 Provides: mail-transport-agent
4695 Conflicts: mail-transport-agent
4696 Replaces: mail-transport-agent
4698 ensuring that only one MTA can be installed at any one
4703 <sect id="sourcebinarydeps">
4704 <heading>Relationships between source and binary packages -
4705 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4706 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4710 Source packages that require certain binary packages to be
4711 installed or absent at the time of building the package
4712 can declare relationships to those binary packages.
4716 This is done using the <tt>Build-Depends</tt>,
4717 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4718 <tt>Build-Conflicts-Indep</tt> control file fields.
4722 Build-dependencies on "build-essential" binary packages can be
4723 omitted. Please see <ref id="pkg-relations"> for more information.
4727 The dependencies and conflicts they define must be satisfied
4728 (as defined earlier for binary packages) in order to invoke
4729 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4731 If you make "build-arch" or "binary-arch", you need
4732 Build-Depends. If you make "build-indep" or
4733 "binary-indep", you need Build-Depends and
4734 Build-Depends-Indep. If you make "build" or "binary",
4738 There is no Build-Depends-Arch; this role is essentially
4739 met with Build-Depends. Anyone building the
4740 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4741 is basically assumed to be building the whole package
4742 anyway and so installs all build dependencies. The
4743 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4744 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4745 does not yet know how to check for its existence) and
4746 <tt>binary-arch</tt>.
4749 The purpose of the original split, I recall, was so that
4750 the autobuilders wouldn't need to install extra packages
4751 needed only for the binary-indep targets. But without a
4752 build-arch/build-indep split, this didn't work, since
4753 most of the work is done in the build target, not in the
4759 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4761 The <tt>Build-Depends</tt> and
4762 <tt>Build-Conflicts</tt> fields must be satisfied when
4763 any of the following targets is invoked:
4764 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4765 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4766 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4768 <tag><tt>Build-Depends-Indep</tt>,
4769 <tt>Build-Conflicts-Indep</tt></tag>
4771 The <tt>Build-Depends-Indep</tt> and
4772 <tt>Build-Conflicts-Indep</tt> fields must be
4773 satisfied when any of the following targets is
4774 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4775 <tt>binary</tt> and <tt>binary-indep</tt>.
4785 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4788 Packages containing shared libraries must be constructed with
4789 a little care to make sure that the shared library is always
4790 available. This is especially important for packages whose
4791 shared libraries are vitally important, such as the C library
4792 (currently <tt>libc6</tt>).
4796 Packages involving shared libraries should be split up into
4797 several binary packages. This section mostly deals with how
4798 this separation is to be accomplished; rules for files within
4799 the shared library packages are in <ref id="libraries"> instead.
4802 <sect id="sharedlibs-runtime">
4803 <heading>Run-time shared libraries</heading>
4806 The run-time shared library needs to be placed in a package
4807 whose name changes whenever the shared object version
4810 Since it is common place to install several versions of a
4811 package that just provides shared libraries, it is a
4812 good idea that the library package should not
4813 contain any extraneous non-versioned files, unless they
4814 happen to be in versioned directories.</p>
4816 The most common mechanism is to place it in a package
4818 <package><var>libraryname</var><var>soversion</var></package>,
4819 where <file><var>soversion</var></file> is the version number
4820 in the soname of the shared library<footnote>
4821 The soname is the shared object name: it's the thing
4822 that has to match exactly between building an executable
4823 and running it for the dynamic linker to be able run the
4824 program. For example, if the soname of the library is
4825 <file>libfoo.so.6</file>, the library package would be
4826 called <file>libfoo6</file>.
4828 Alternatively, if it would be confusing to directly append
4829 <var>soversion</var> to <var>libraryname</var> (e.g. because
4830 <var>libraryname</var> itself ends in a number), you may use
4831 <package><var>libraryname</var>-<var>soversion</var></package> and
4832 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4837 If you have several shared libraries built from the same
4838 source tree you may lump them all together into a single
4839 shared library package, provided that you change all of
4840 their sonames at once (so that you don't get filename
4841 clashes if you try to install different versions of the
4842 combined shared libraries package).
4846 The package should install the shared libraries under
4847 their normal names. For example, the <package>libgdbm3</package>
4848 package should install <file>libgdbm.so.3.0.0</file> as
4849 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4850 renamed or re-linked by any <prgn>prerm</prgn> or
4851 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4852 of renaming things safely without affecting running programs,
4853 and attempts to interfere with this are likely to lead to
4858 Shared libraries should not be installed executable, since
4859 the dynamic linker does not require this and trying to
4860 execute a shared library usually results in a core dump.
4864 The run-time library package should include the symbolic link that
4865 <prgn>ldconfig</prgn> would create for the shared libraries.
4866 For example, the <package>libgdbm3</package> package should include
4867 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4868 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4869 linker (for example <prgn>ld.so</prgn> or
4870 <prgn>ld-linux.so.*</prgn>) can find the library between the
4871 time that <prgn>dpkg</prgn> installs it and the time that
4872 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4874 The package management system requires the library to be
4875 placed before the symbolic link pointing to it in the
4876 <file>.deb</file> file. This is so that when
4877 <prgn>dpkg</prgn> comes to install the symlink
4878 (overwriting the previous symlink pointing at an older
4879 version of the library), the new shared library is already
4880 in place. In the past, this was achieved by creating the
4881 library in the temporary packaging directory before
4882 creating the symlink. Unfortunately, this was not always
4883 effective, since the building of the tar file in the
4884 <file>.deb</file> depended on the behavior of the underlying
4885 file system. Some file systems (such as reiserfs) reorder
4886 the files so that the order of creation is forgotten.
4887 Since version 1.7.0, <prgn>dpkg</prgn>
4888 reorders the files itself as necessary when building a
4889 package. Thus it is no longer important to concern
4890 oneself with the order of file creation.
4894 <sect1 id="ldconfig">
4895 <heading><tt>ldconfig</tt></heading>
4898 Any package installing shared libraries in one of the default
4899 library directories of the dynamic linker (which are currently
4900 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4901 listed in <file>/etc/ld.so.conf</file><footnote>
4903 <list compact="compact">
4904 <item>/usr/local/lib</item>
4905 <item>/usr/lib/libc5-compat</item>
4906 <item>/lib/libc5-compat</item>
4909 must use <prgn>ldconfig</prgn> to update the shared library
4914 The package maintainer scripts must only call
4915 <prgn>ldconfig</prgn> under these circumstances:
4916 <list compact="compact">
4917 <item>When the <prgn>postinst</prgn> script is run with a
4918 first argument of <tt>configure</tt>, the script must call
4919 <prgn>ldconfig</prgn>, and may optionally invoke
4920 <prgn>ldconfig</prgn> at other times.
4922 <item>When the <prgn>postrm</prgn> script is run with a
4923 first argument of <tt>remove</tt>, the script should call
4924 <prgn>ldconfig</prgn>.
4929 During install or upgrade, the preinst is called before
4930 the new files are installed, so calling "ldconfig" is
4931 pointless. The preinst of an existing package can also be
4932 called if an upgrade fails. However, this happens during
4933 the critical time when a shared libs may exist on-disk
4934 under a temporary name. Thus, it is dangerous and
4935 forbidden by current policy to call "ldconfig" at this
4940 When a package is installed or upgraded, "postinst
4941 configure" runs after the new files are safely on-disk.
4942 Since it is perfectly safe to invoke ldconfig
4943 unconditionally in a postinst, it is OK for a package to
4944 simply put ldconfig in its postinst without checking the
4945 argument. The postinst can also be called to recover from
4946 a failed upgrade. This happens before any new files are
4947 unpacked, so there is no reason to call "ldconfig" at this
4952 For a package that is being removed, prerm is
4953 called with all the files intact, so calling ldconfig is
4954 useless. The other calls to "prerm" happen in the case of
4955 upgrade at a time when all the files of the old package
4956 are on-disk, so again calling "ldconfig" is pointless.
4960 postrm, on the other hand, is called with the "remove"
4961 argument just after the files are removed, so this is
4962 the proper time to call "ldconfig" to notify the system
4963 of the fact that the shared libraries from the package
4964 are removed. The postrm can be called at several other
4965 times. At the time of "postrm purge", "postrm
4966 abort-install", or "postrm abort-upgrade", calling
4967 "ldconfig" is useless because the shared lib files are
4968 not on-disk. However, when "postrm" is invoked with
4969 arguments "upgrade", "failed-upgrade", or "disappear", a
4970 shared lib may exist on-disk under a temporary filename.
4978 <sect id="sharedlibs-support-files">
4979 <heading>Shared library support files</heading>
4982 If your package contains files whose names do not change with
4983 each change in the library shared object version, you must not
4984 put them in the shared library package. Otherwise, several
4985 versions of the shared library cannot be installed at the same
4986 time without filename clashes, making upgrades and transitions
4987 unnecessarily difficult.
4991 It is recommended that supporting files and run-time support
4992 programs that do not need to be invoked manually by users, but
4993 are nevertheless required for the package to function, be placed
4994 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
4995 preferably under <file>/usr/lib/</file><var>package-name</var>.
4996 If the program or file is architecture independent, the
4997 recommendation is for it to be placed in a subdirectory of
4998 <file>/usr/share</file> instead, preferably under
4999 <file>/usr/share/</file><var>package-name</var>. Following the
5000 <var>package-name</var> naming convention ensures that the file
5001 names change when the shared object version changes.
5005 Run-time support programs that use the shared library but are
5006 not required for the library to function or files used by the
5007 shared library that can be used by any version of the shared
5008 library package should instead be put in a separate package.
5009 This package might typically be named
5010 <package><var>libraryname</var>-tools</package>; note the
5011 absence of the <var>soversion</var> in the package name.
5015 Files and support programs only useful when compiling software
5016 against the library should be included in the development
5017 package for the library.<footnote>
5018 For example, a <file><var>package-name</var>-config</file>
5019 script or <package>pkg-config</package> configuration files.
5024 <sect id="sharedlibs-static">
5025 <heading>Static libraries</heading>
5028 The static library (<file><var>libraryname.a</var></file>)
5029 is usually provided in addition to the shared version.
5030 It is placed into the development package (see below).
5034 In some cases, it is acceptable for a library to be
5035 available in static form only; these cases include:
5037 <item>libraries for languages whose shared library support
5038 is immature or unstable</item>
5039 <item>libraries whose interfaces are in flux or under
5040 development (commonly the case when the library's
5041 major version number is zero, or where the ABI breaks
5042 across patchlevels)</item>
5043 <item>libraries which are explicitly intended to be
5044 available only in static form by their upstream
5049 <sect id="sharedlibs-dev">
5050 <heading>Development files</heading>
5053 The development files associated to a shared library need to be
5054 placed in a package called
5055 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5056 or if you prefer only to support one development version at a
5057 time, <package><var>libraryname</var>-dev</package>.
5061 In case several development versions of a library exist, you may
5062 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5063 <ref id="conflicts">) to ensure that the user only installs one
5064 development version at a time (as different development versions are
5065 likely to have the same header files in them, which would cause a
5066 filename clash if both were installed).
5070 The development package should contain a symlink for the associated
5071 shared library without a version number. For example, the
5072 <package>libgdbm-dev</package> package should include a symlink
5073 from <file>/usr/lib/libgdbm.so</file> to
5074 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5075 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5076 <file>libgdbm.so</file> when compiling dynamically.
5080 <sect id="sharedlibs-intradeps">
5081 <heading>Dependencies between the packages of the same library</heading>
5084 Typically the development version should have an exact
5085 version dependency on the runtime library, to make sure that
5086 compilation and linking happens correctly. The
5087 <tt>${binary:Version}</tt> substitution variable can be
5088 useful for this purpose.
5090 Previously, <tt>${Source-Version}</tt> was used, but its name
5091 was confusing and it has been deprecated since dpkg 1.13.19.
5096 <sect id="sharedlibs-shlibdeps">
5097 <heading>Dependencies between the library and other packages -
5098 the <tt>shlibs</tt> system</heading>
5101 If a package contains a binary or library which links to a
5102 shared library, we must ensure that when the package is
5103 installed on the system, all of the libraries needed are
5104 also installed. This requirement led to the creation of the
5105 <tt>shlibs</tt> system, which is very simple in its design:
5106 any package which <em>provides</em> a shared library also
5107 provides information on the package dependencies required to
5108 ensure the presence of this library, and any package which
5109 <em>uses</em> a shared library uses this information to
5110 determine the dependencies it requires. The files which
5111 contain the mapping from shared libraries to the necessary
5112 dependency information are called <file>shlibs</file> files.
5116 Thus, when a package is built which contains any shared
5117 libraries, it must provide a <file>shlibs</file> file for other
5118 packages to use, and when a package is built which contains
5119 any shared libraries or compiled binaries, it must run
5120 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5121 on these to determine the libraries used and hence the
5122 dependencies needed by this package.<footnote>
5124 In the past, the shared libraries linked to were
5125 determined by calling <prgn>ldd</prgn>, but now
5126 <prgn>objdump</prgn> is used to do this. The only
5127 change this makes to package building is that
5128 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5129 libraries, whereas in the past this was unnecessary.
5130 The rest of this footnote explains the advantage that
5135 We say that a binary <tt>foo</tt> <em>directly</em> uses
5136 a library <tt>libbar</tt> if it is explicitly linked
5137 with that library (that is, it uses the flag
5138 <tt>-lbar</tt> during the linking stage). Other
5139 libraries that are needed by <tt>libbar</tt> are linked
5140 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5141 linker will load them automatically when it loads
5142 <tt>libbar</tt>. A package should depend on
5143 the libraries it directly uses, and the dependencies for
5144 those libraries should automatically pull in the other
5149 Unfortunately, the <prgn>ldd</prgn> program shows both
5150 the directly and indirectly used libraries, meaning that
5151 the dependencies determined included both direct and
5152 indirect dependencies. The use of <prgn>objdump</prgn>
5153 avoids this problem by determining only the directly
5158 A good example of where this helps is the following. We
5159 could update <tt>libimlib</tt> with a new version that
5160 supports a new graphics format called dgf (but retaining
5161 the same major version number). If we used the old
5162 <prgn>ldd</prgn> method, every package that uses
5163 <tt>libimlib</tt> would need to be recompiled so it
5164 would also depend on <tt>libdgf</tt> or it wouldn't run
5165 due to missing symbols. However with the new system,
5166 packages using <tt>libimlib</tt> can rely on
5167 <tt>libimlib</tt> itself having the dependency on
5168 <tt>libdgf</tt> and so they would not need rebuilding.
5174 In the following sections, we will first describe where the
5175 various <tt>shlibs</tt> files are to be found, then how to
5176 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5177 file format and how to create them if your package contains a
5182 <heading>The <tt>shlibs</tt> files present on the system</heading>
5185 There are several places where <tt>shlibs</tt> files are
5186 found. The following list gives them in the order in which
5188 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5189 (The first one which gives the required information is used.)
5195 <p><file>debian/shlibs.local</file></p>
5198 This lists overrides for this package. Its use is
5199 described below (see <ref id="shlibslocal">).
5204 <p><file>/etc/dpkg/shlibs.override</file></p>
5207 This lists global overrides. This list is normally
5208 empty. It is maintained by the local system
5214 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5217 When packages are being built, any
5218 <file>debian/shlibs</file> files are copied into the
5219 control file area of the temporary build directory and
5220 given the name <file>shlibs</file>. These files give
5221 details of any shared libraries included in the
5223 An example may help here. Let us say that the
5224 source package <tt>foo</tt> generates two binary
5225 packages, <tt>libfoo2</tt> and
5226 <tt>foo-runtime</tt>. When building the binary
5227 packages, the two packages are created in the
5228 directories <file>debian/libfoo2</file> and
5229 <file>debian/foo-runtime</file> respectively.
5230 (<file>debian/tmp</file> could be used instead of one
5231 of these.) Since <tt>libfoo2</tt> provides the
5232 <tt>libfoo</tt> shared library, it will require a
5233 <tt>shlibs</tt> file, which will be installed in
5234 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5236 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5237 when <prgn>dpkg-shlibdeps</prgn> is run on the
5239 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5241 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5242 determine whether <tt>foo-prog</tt>'s library
5243 dependencies are satisfied by any of the libraries
5244 provided by <tt>libfoo2</tt>. For this reason,
5245 <prgn>dpkg-shlibdeps</prgn> must only be run once
5246 all of the individual binary packages'
5247 <tt>shlibs</tt> files have been installed into the
5254 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5257 These are the <file>shlibs</file> files corresponding to
5258 all of the packages installed on the system, and are
5259 maintained by the relevant package maintainers.
5264 <p><file>/etc/dpkg/shlibs.default</file></p>
5267 This file lists any shared libraries whose packages
5268 have failed to provide correct <file>shlibs</file> files.
5269 It was used when the <file>shlibs</file> setup was first
5270 introduced, but it is now normally empty. It is
5271 maintained by the <tt>dpkg</tt> maintainer.
5279 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5280 <file>shlibs</file> files</heading>
5284 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5285 into your <file>debian/rules</file> file. If your package
5286 contains only compiled binaries and libraries (but no scripts),
5287 you can use a command such as:
5288 <example compact="compact">
5289 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5290 debian/tmp/usr/lib/*
5292 Otherwise, you will need to explicitly list the compiled
5293 binaries and libraries.<footnote>
5294 If you are using <tt>debhelper</tt>, the
5295 <prgn>dh_shlibdeps</prgn> program will do this work for
5296 you. It will also correctly handle multi-binary
5302 This command puts the dependency information into the
5303 <file>debian/substvars</file> file, which is then used by
5304 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5305 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5306 field in the control file for this to work.
5310 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5311 done. If it does complain you might need to create your own
5312 <file>debian/shlibs.local</file> file, as explained below (see
5313 <ref id="shlibslocal">).
5317 If you have multiple binary packages, you will need to call
5318 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5319 compiled libraries or binaries. In such a case, you will
5320 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5321 utilities to specify a different <file>substvars</file> file.
5325 If you are creating a udeb for use in the Debian Installer, you
5326 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5327 the dependency line of type <tt>udeb</tt> by adding
5328 <tt>-tudeb</tt> as option<footnote>
5329 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5330 will automatically add this option if it knows it is
5332 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5333 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5334 fall back to the regular dependency line.
5338 For more details on dpkg-shlibdeps, please see
5339 <ref id="pkg-dpkg-shlibdeps"> and
5340 <manref name="dpkg-shlibdeps" section="1">.
5345 <heading>The <file>shlibs</file> File Format</heading>
5348 Each <file>shlibs</file> file has the same format. Lines
5349 beginning with <tt>#</tt> are considered to be comments and
5350 are ignored. Each line is of the form:
5351 <example compact="compact">
5352 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5357 We will explain this by reference to the example of the
5358 <tt>zlib1g</tt> package, which (at the time of writing)
5359 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5363 <var>type</var> is an optional element that indicates the type
5364 of package for which the line is valid. The only type currently
5365 in use is <tt>udeb</tt>. The colon and space after the type are
5370 <var>library-name</var> is the name of the shared library,
5371 in this case <tt>libz</tt>. (This must match the name part
5372 of the soname, see below.)
5376 <var>soname-version</var> is the version part of the soname of
5377 the library. The soname is the thing that must exactly match
5378 for the library to be recognized by the dynamic linker, and is
5380 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5381 example, <tt>libz.so.1</tt>.<footnote>
5382 This can be determined using the command
5383 <example compact="compact">
5384 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5387 The version part is the part which comes after
5388 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5392 <var>dependencies</var> has the same syntax as a dependency
5393 field in a binary package control file. It should give
5394 details of which packages are required to satisfy a binary
5395 built against the version of the library contained in the
5396 package. See <ref id="depsyntax"> for details.
5400 In our example, if the first version of the <tt>zlib1g</tt>
5401 package which contained a minor number of at least
5402 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5403 <tt>shlibs</tt> entry for this library could say:
5404 <example compact="compact">
5405 libz 1 zlib1g (>= 1:1.1.3)
5407 The version-specific dependency is to avoid warnings from
5408 the dynamic linker about using older shared libraries with
5413 As zlib1g also provides a udeb containing the shared library,
5414 there would also be a second line:
5415 <example compact="compact">
5416 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5422 <heading>Providing a <file>shlibs</file> file</heading>
5425 If your package provides a shared library, you need to create
5426 a <file>shlibs</file> file following the format described above.
5427 It is usual to call this file <file>debian/shlibs</file> (but if
5428 you have multiple binary packages, you might want to call it
5429 <file>debian/shlibs.<var>package</var></file> instead). Then
5430 let <file>debian/rules</file> install it in the control area:
5431 <example compact="compact">
5432 install -m644 debian/shlibs debian/tmp/DEBIAN
5434 or, in the case of a multi-binary package:
5435 <example compact="compact">
5436 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5438 An alternative way of doing this is to create the
5439 <file>shlibs</file> file in the control area directly from
5440 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5441 file at all,<footnote>
5442 This is what <prgn>dh_makeshlibs</prgn> in the
5443 <tt>debhelper</tt> suite does. If your package also has a udeb
5444 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5445 automatically generate the <tt>udeb:</tt> lines if you specify
5446 the name of the udeb with the <tt>--add-udeb</tt> option.
5448 since the <file>debian/shlibs</file> file itself is ignored by
5449 <prgn>dpkg-shlibdeps</prgn>.
5453 As <prgn>dpkg-shlibdeps</prgn> reads the
5454 <file>DEBIAN/shlibs</file> files in all of the binary packages
5455 being built from this source package, all of the
5456 <file>DEBIAN/shlibs</file> files should be installed before
5457 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5462 <sect1 id="shlibslocal">
5463 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5466 This file is intended only as a <em>temporary</em> fix if
5467 your binaries or libraries depend on a library whose package
5468 does not yet provide a correct <file>shlibs</file> file.
5472 We will assume that you are trying to package a binary
5473 <tt>foo</tt>. When you try running
5474 <prgn>dpkg-shlibdeps</prgn> you get the following error
5475 message (<tt>-O</tt> displays the dependency information on
5476 <tt>stdout</tt> instead of writing it to
5477 <tt>debian/substvars</tt>, and the lines have been wrapped
5478 for ease of reading):
5479 <example compact="compact">
5480 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5481 dpkg-shlibdeps: warning: unable to find dependency
5482 information for shared library libbar (soname 1,
5483 path /usr/lib/libbar.so.1, dependency field Depends)
5484 shlibs:Depends=libc6 (>= 2.2.2-2)
5486 You can then run <prgn>ldd</prgn> on the binary to find the
5487 full location of the library concerned:
5488 <example compact="compact">
5490 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5491 libc.so.6 => /lib/libc.so.6 (0x40032000)
5492 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5494 So the <prgn>foo</prgn> binary depends on the
5495 <prgn>libbar</prgn> shared library, but no package seems to
5496 provide a <file>*.shlibs</file> file handling
5497 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5498 determine the package responsible:
5499 <example compact="compact">
5500 $ dpkg -S /usr/lib/libbar.so.1
5501 bar1: /usr/lib/libbar.so.1
5502 $ dpkg -s bar1 | grep Version
5505 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5506 is the one we are using. Now we can file a bug against the
5507 <tt>bar1</tt> package and create our own
5508 <file>debian/shlibs.local</file> to locally fix the problem.
5509 Including the following line into your
5510 <file>debian/shlibs.local</file> file:
5511 <example compact="compact">
5512 libbar 1 bar1 (>= 1.0-1)
5514 should allow the package build to work.
5518 As soon as the maintainer of <tt>bar1</tt> provides a
5519 correct <file>shlibs</file> file, you should remove this line
5520 from your <file>debian/shlibs.local</file> file. (You should
5521 probably also then have a versioned <tt>Build-Depends</tt>
5522 on <tt>bar1</tt> to help ensure that others do not have the
5523 same problem building your package.)
5532 <chapt id="opersys"><heading>The Operating System</heading>
5535 <heading>File system hierarchy</heading>
5539 <heading>File System Structure</heading>
5542 The location of all installed files and directories must
5543 comply with the Filesystem Hierarchy Standard (FHS),
5544 version 2.3, with the exceptions noted below, and except
5545 where doing so would violate other terms of Debian
5546 Policy. The following exceptions to the FHS apply:
5551 The optional rules related to user specific
5552 configuration files for applications are stored in
5553 the user's home directory are relaxed. It is
5554 recommended that such files start with the
5555 '<tt>.</tt>' character (a "dot file"), and if an
5556 application needs to create more than one dot file
5557 then the preferred placement is in a subdirectory
5558 with a name starting with a '.' character, (a "dot
5559 directory"). In this case it is recommended the
5560 configuration files not start with the '.'
5566 The requirement for amd64 to use <file>/lib64</file>
5567 for 64 bit binaries is removed.
5572 The requirement that
5573 <file>/usr/local/share/man</file> be "synonymous"
5574 with <file>/usr/local/man</file> is relaxed to a
5579 The requirement that windowmanagers with a single
5580 configuration file call it <file>system.*wmrc</file>
5581 is removed, as is the restriction that the window
5582 manager subdirectory be named identically to the
5583 window manager name itself.
5588 The requirement that boot manager configuration
5589 files live in <file>/etc</file>, or at least are
5590 symlinked there, is relaxed to a recommendation.
5597 The version of this document referred here can be
5598 found in the <tt>debian-policy</tt> package or on <url
5599 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5600 name="FHS (Debian copy)"> alongside this manual (or, if
5601 you have the <package>debian-policy</package> installed,
5603 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5604 (local copy)">). The
5605 latest version, which may be a more recent version, may
5607 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5608 Specific questions about following the standard may be
5609 asked on the <tt>debian-devel</tt> mailing list, or
5610 referred to the FHS mailing list (see the
5611 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5617 <heading>Site-specific programs</heading>
5620 As mandated by the FHS, packages must not place any
5621 files in <file>/usr/local</file>, either by putting them in
5622 the file system archive to be unpacked by <prgn>dpkg</prgn>
5623 or by manipulating them in their maintainer scripts.
5627 However, the package may create empty directories below
5628 <file>/usr/local</file> so that the system administrator knows
5629 where to place site-specific files. These are not
5630 directories <em>in</em> <file>/usr/local</file>, but are
5631 children of directories in <file>/usr/local</file>. These
5632 directories (<file>/usr/local/*/dir/</file>)
5633 should be removed on package removal if they are
5638 Note, that this applies only to directories <em>below</em>
5639 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5640 Packages must not create sub-directories in the directory
5641 <file>/usr/local</file> itself, except those listed in FHS,
5642 section 4.5. However, you may create directories below
5643 them as you wish. You must not remove any of the
5644 directories listed in 4.5, even if you created them.
5648 Since <file>/usr/local</file> can be mounted read-only from a
5649 remote server, these directories must be created and
5650 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5651 maintainer scripts and not be included in the
5652 <file>.deb</file> archive. These scripts must not fail if
5653 either of these operations fail.
5657 For example, the <tt>emacsen-common</tt> package could
5658 contain something like
5659 <example compact="compact">
5660 if [ ! -e /usr/local/share/emacs ]
5662 if mkdir /usr/local/share/emacs 2>/dev/null
5664 chown root:staff /usr/local/share/emacs
5665 chmod 2775 /usr/local/share/emacs
5669 in its <prgn>postinst</prgn> script, and
5670 <example compact="compact">
5671 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5672 rmdir /usr/local/share/emacs 2>/dev/null || true
5674 in the <prgn>prerm</prgn> script. (Note that this form is
5675 used to ensure that if the script is interrupted, the
5676 directory <file>/usr/local/share/emacs</file> will still be
5681 If you do create a directory in <file>/usr/local</file> for
5682 local additions to a package, you should ensure that
5683 settings in <file>/usr/local</file> take precedence over the
5684 equivalents in <file>/usr</file>.
5688 However, because <file>/usr/local</file> and its contents are
5689 for exclusive use of the local administrator, a package
5690 must not rely on the presence or absence of files or
5691 directories in <file>/usr/local</file> for normal operation.
5695 The <file>/usr/local</file> directory itself and all the
5696 subdirectories created by the package should (by default) have
5697 permissions 2775 (group-writable and set-group-id) and be
5698 owned by <tt>root:staff</tt>.
5703 <heading>The system-wide mail directory</heading>
5705 The system-wide mail directory is <file>/var/mail</file>. This
5706 directory is part of the base system and should not owned
5707 by any particular mail agents. The use of the old
5708 location <file>/var/spool/mail</file> is deprecated, even
5709 though the spool may still be physically located there.
5715 <heading>Users and groups</heading>
5718 <heading>Introduction</heading>
5720 The Debian system can be configured to use either plain or
5725 Some user ids (UIDs) and group ids (GIDs) are reserved
5726 globally for use by certain packages. Because some
5727 packages need to include files which are owned by these
5728 users or groups, or need the ids compiled into binaries,
5729 these ids must be used on any Debian system only for the
5730 purpose for which they are allocated. This is a serious
5731 restriction, and we should avoid getting in the way of
5732 local administration policies. In particular, many sites
5733 allocate users and/or local system groups starting at 100.
5737 Apart from this we should have dynamically allocated ids,
5738 which should by default be arranged in some sensible
5739 order, but the behavior should be configurable.
5743 Packages other than <tt>base-passwd</tt> must not modify
5744 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5745 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5750 <heading>UID and GID classes</heading>
5752 The UID and GID numbers are divided into classes as
5758 Globally allocated by the Debian project, the same
5759 on every Debian system. These ids will appear in
5760 the <file>passwd</file> and <file>group</file> files of all
5761 Debian systems, new ids in this range being added
5762 automatically as the <tt>base-passwd</tt> package is
5767 Packages which need a single statically allocated
5768 uid or gid should use one of these; their
5769 maintainers should ask the <tt>base-passwd</tt>
5777 Dynamically allocated system users and groups.
5778 Packages which need a user or group, but can have
5779 this user or group allocated dynamically and
5780 differently on each system, should use <tt>adduser
5781 --system</tt> to create the group and/or user.
5782 <prgn>adduser</prgn> will check for the existence of
5783 the user or group, and if necessary choose an unused
5784 id based on the ranges specified in
5785 <file>adduser.conf</file>.
5789 <tag>1000-29999:</tag>
5792 Dynamically allocated user accounts. By default
5793 <prgn>adduser</prgn> will choose UIDs and GIDs for
5794 user accounts in this range, though
5795 <file>adduser.conf</file> may be used to modify this
5800 <tag>30000-59999:</tag>
5805 <tag>60000-64999:</tag>
5808 Globally allocated by the Debian project, but only
5809 created on demand. The ids are allocated centrally
5810 and statically, but the actual accounts are only
5811 created on users' systems on demand.
5815 These ids are for packages which are obscure or
5816 which require many statically-allocated ids. These
5817 packages should check for and create the accounts in
5818 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5819 <prgn>adduser</prgn> if it has this facility) if
5820 necessary. Packages which are likely to require
5821 further allocations should have a "hole" left after
5822 them in the allocation, to give them room to
5827 <tag>65000-65533:</tag>
5835 User <tt>nobody</tt>. The corresponding gid refers
5836 to the group <tt>nogroup</tt>.
5843 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5844 not</em> be used, because it is the error return
5853 <sect id="sysvinit">
5854 <heading>System run levels and <file>init.d</file> scripts</heading>
5856 <sect1 id="/etc/init.d">
5857 <heading>Introduction</heading>
5860 The <file>/etc/init.d</file> directory contains the scripts
5861 executed by <prgn>init</prgn> at boot time and when the
5862 init state (or "runlevel") is changed (see <manref
5863 name="init" section="8">).
5867 There are at least two different, yet functionally
5868 equivalent, ways of handling these scripts. For the sake
5869 of simplicity, this document describes only the symbolic
5870 link method. However, it must not be assumed by maintainer
5871 scripts that this method is being used, and any automated
5872 manipulation of the various runlevel behaviors by
5873 maintainer scripts must be performed using
5874 <prgn>update-rc.d</prgn> as described below and not by
5875 manually installing or removing symlinks. For information
5876 on the implementation details of the other method,
5877 implemented in the <tt>file-rc</tt> package, please refer
5878 to the documentation of that package.
5882 These scripts are referenced by symbolic links in the
5883 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5884 runlevels, <prgn>init</prgn> looks in the directory
5885 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5886 execute, where <tt><var>n</var></tt> is the runlevel that
5887 is being changed to, or <tt>S</tt> for the boot-up
5892 The names of the links all have the form
5893 <file>S<var>mm</var><var>script</var></file> or
5894 <file>K<var>mm</var><var>script</var></file> where
5895 <var>mm</var> is a two-digit number and <var>script</var>
5896 is the name of the script (this should be the same as the
5897 name of the actual script in <file>/etc/init.d</file>).
5901 When <prgn>init</prgn> changes runlevel first the targets
5902 of the links whose names start with a <tt>K</tt> are
5903 executed, each with the single argument <tt>stop</tt>,
5904 followed by the scripts prefixed with an <tt>S</tt>, each
5905 with the single argument <tt>start</tt>. (The links are
5906 those in the <file>/etc/rc<var>n</var>.d</file> directory
5907 corresponding to the new runlevel.) The <tt>K</tt> links
5908 are responsible for killing services and the <tt>S</tt>
5909 link for starting services upon entering the runlevel.
5913 For example, if we are changing from runlevel 2 to
5914 runlevel 3, init will first execute all of the <tt>K</tt>
5915 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5916 all of the <tt>S</tt> prefixed scripts in that directory.
5917 The links starting with <tt>K</tt> will cause the
5918 referred-to file to be executed with an argument of
5919 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5924 The two-digit number <var>mm</var> is used to determine
5925 the order in which to run the scripts: low-numbered links
5926 have their scripts run first. For example, the
5927 <tt>K20</tt> scripts will be executed before the
5928 <tt>K30</tt> scripts. This is used when a certain service
5929 must be started before another. For example, the name
5930 server <prgn>bind</prgn> might need to be started before
5931 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5932 can set up its access lists. In this case, the script
5933 that starts <prgn>bind</prgn> would have a lower number
5934 than the script that starts <prgn>inn</prgn> so that it
5936 <example compact="compact">
5943 The two runlevels 0 (halt) and 6 (reboot) are slightly
5944 different. In these runlevels, the links with an
5945 <tt>S</tt> prefix are still called after those with a
5946 <tt>K</tt> prefix, but they too are called with the single
5947 argument <tt>stop</tt>.
5952 <heading>Writing the scripts</heading>
5955 Packages that include daemons for system services should
5956 place scripts in <file>/etc/init.d</file> to start or stop
5957 services at boot time or during a change of runlevel.
5958 These scripts should be named
5959 <file>/etc/init.d/<var>package</var></file>, and they should
5960 accept one argument, saying what to do:
5963 <tag><tt>start</tt></tag>
5964 <item>start the service,</item>
5966 <tag><tt>stop</tt></tag>
5967 <item>stop the service,</item>
5969 <tag><tt>restart</tt></tag>
5970 <item>stop and restart the service if it's already running,
5971 otherwise start the service</item>
5973 <tag><tt>reload</tt></tag>
5974 <item><p>cause the configuration of the service to be
5975 reloaded without actually stopping and restarting
5978 <tag><tt>force-reload</tt></tag>
5979 <item>cause the configuration to be reloaded if the
5980 service supports this, otherwise restart the
5984 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5985 <tt>force-reload</tt> options should be supported by all
5986 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5991 The <file>init.d</file> scripts must ensure that they will
5992 behave sensibly (i.e., returning success and not starting
5993 multiple copies of a service) if invoked with <tt>start</tt>
5994 when the service is already running, or with <tt>stop</tt>
5995 when it isn't, and that they don't kill unfortunately-named
5996 user processes. The best way to achieve this is usually to
5997 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6002 If a service reloads its configuration automatically (as
6003 in the case of <prgn>cron</prgn>, for example), the
6004 <tt>reload</tt> option of the <file>init.d</file> script
6005 should behave as if the configuration has been reloaded
6010 The <file>/etc/init.d</file> scripts must be treated as
6011 configuration files, either (if they are present in the
6012 package, that is, in the .deb file) by marking them as
6013 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6014 by managing them correctly in the maintainer scripts (see
6015 <ref id="config-files">). This is important since we want
6016 to give the local system administrator the chance to adapt
6017 the scripts to the local system, e.g., to disable a
6018 service without de-installing the package, or to specify
6019 some special command line options when starting a service,
6020 while making sure their changes aren't lost during the next
6025 These scripts should not fail obscurely when the
6026 configuration files remain but the package has been
6027 removed, as configuration files remain on the system after
6028 the package has been removed. Only when <prgn>dpkg</prgn>
6029 is executed with the <tt>--purge</tt> option will
6030 configuration files be removed. In particular, as the
6031 <file>/etc/init.d/<var>package</var></file> script itself is
6032 usually a <tt>conffile</tt>, it will remain on the system
6033 if the package is removed but not purged. Therefore, you
6034 should include a <tt>test</tt> statement at the top of the
6036 <example compact="compact">
6037 test -f <var>program-executed-later-in-script</var> || exit 0
6042 Often there are some variables in the <file>init.d</file>
6043 scripts whose values control the behavior of the scripts,
6044 and which a system administrator is likely to want to
6045 change. As the scripts themselves are frequently
6046 <tt>conffile</tt>s, modifying them requires that the
6047 administrator merge in their changes each time the package
6048 is upgraded and the <tt>conffile</tt> changes. To ease
6049 the burden on the system administrator, such configurable
6050 values should not be placed directly in the script.
6051 Instead, they should be placed in a file in
6052 <file>/etc/default</file>, which typically will have the same
6053 base name as the <file>init.d</file> script. This extra file
6054 should be sourced by the script when the script runs. It
6055 must contain only variable settings and comments in SUSv3
6056 <prgn>sh</prgn> format. It may either be a
6057 <tt>conffile</tt> or a configuration file maintained by
6058 the package maintainer scripts. See <ref id="config-files">
6063 To ensure that vital configurable values are always
6064 available, the <file>init.d</file> script should set default
6065 values for each of the shell variables it uses, either
6066 before sourcing the <file>/etc/default/</file> file or
6067 afterwards using something like the <tt>:
6068 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6069 script must behave sensibly and not fail if the
6070 <file>/etc/default</file> file is deleted.
6074 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6075 as temporary filesystems<footnote>
6076 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6077 options in <file>/etc/default/rcS</file>.
6078 </footnote>, so the <file>init.d</file> scripts must handle this
6079 correctly. This will typically amount to creating any required
6080 subdirectories dynamically when the <file>init.d</file> script
6081 is run, rather than including them in the package and relying on
6082 <prgn>dpkg</prgn> to create them.
6087 <heading>Interfacing with the initscript system</heading>
6090 Maintainers should use the abstraction layer provided by
6091 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6092 programs to deal with initscripts in their packages'
6093 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6094 and <prgn>postrm</prgn>.
6098 Directly managing the /etc/rc?.d links and directly
6099 invoking the <file>/etc/init.d/</file> initscripts should
6100 be done only by packages providing the initscript
6101 subsystem (such as <prgn>sysv-rc</prgn> and
6102 <prgn>file-rc</prgn>).
6106 <heading>Managing the links</heading>
6109 The program <prgn>update-rc.d</prgn> is provided for
6110 package maintainers to arrange for the proper creation and
6111 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6112 or their functional equivalent if another method is being
6113 used. This may be used by maintainers in their packages'
6114 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6118 You must not include any <file>/etc/rc<var>n</var>.d</file>
6119 symbolic links in the actual archive or manually create or
6120 remove the symbolic links in maintainer scripts; you must
6121 use the <prgn>update-rc.d</prgn> program instead. (The
6122 former will fail if an alternative method of maintaining
6123 runlevel information is being used.) You must not include
6124 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6125 in the archive either. (Only the <tt>sysvinit</tt>
6130 By default <prgn>update-rc.d</prgn> will start services in
6131 each of the multi-user state runlevels (2, 3, 4, and 5)
6132 and stop them in the halt runlevel (0), the single-user
6133 runlevel (1) and the reboot runlevel (6). The system
6134 administrator will have the opportunity to customize
6135 runlevels by simply adding, moving, or removing the
6136 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6137 symbolic links are being used, or by modifying
6138 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6143 To get the default behavior for your package, put in your
6144 <prgn>postinst</prgn> script
6145 <example compact="compact">
6146 update-rc.d <var>package</var> defaults
6148 and in your <prgn>postrm</prgn>
6149 <example compact="compact">
6150 if [ "$1" = purge ]; then
6151 update-rc.d <var>package</var> remove
6153 </example>. Note that if your package changes runlevels
6154 or priority, you may have to remove and recreate the links,
6155 since otherwise the old links may persist. Refer to the
6156 documentation of <prgn>update-rc.d</prgn>.
6160 This will use a default sequence number of 20. If it does
6161 not matter when or in which order the <file>init.d</file>
6162 script is run, use this default. If it does, then you
6163 should talk to the maintainer of the <prgn>sysvinit</prgn>
6164 package or post to <tt>debian-devel</tt>, and they will
6165 help you choose a number.
6169 For more information about using <tt>update-rc.d</tt>,
6170 please consult its man page <manref name="update-rc.d"
6176 <heading>Running initscripts</heading>
6178 The program <prgn>invoke-rc.d</prgn> is provided to make
6179 it easier for package maintainers to properly invoke an
6180 initscript, obeying runlevel and other locally-defined
6181 constraints that might limit a package's right to start,
6182 stop and otherwise manage services. This program may be
6183 used by maintainers in their packages' scripts.
6187 The package maintainer scripts must use
6188 <prgn>invoke-rc.d</prgn> to invoke the
6189 <file>/etc/init.d/*</file> initscripts, instead of
6190 calling them directly.
6194 By default, <prgn>invoke-rc.d</prgn> will pass any
6195 action requests (start, stop, reload, restart...) to the
6196 <file>/etc/init.d</file> script, filtering out requests
6197 to start or restart a service out of its intended
6202 Most packages will simply need to change:
6203 <example compact="compact">/etc/init.d/<package>
6204 <action></example> in their <prgn>postinst</prgn>
6205 and <prgn>prerm</prgn> scripts to:
6206 <example compact="compact">
6207 if which invoke-rc.d >/dev/null 2>&1; then
6208 invoke-rc.d <var>package</var> <action>
6210 /etc/init.d/<var>package</var> <action>
6216 A package should register its initscript services using
6217 <prgn>update-rc.d</prgn> before it tries to invoke them
6218 using <prgn>invoke-rc.d</prgn>. Invocation of
6219 unregistered services may fail.
6223 For more information about using
6224 <prgn>invoke-rc.d</prgn>, please consult its man page
6225 <manref name="invoke-rc.d" section="8">.
6231 <heading>Boot-time initialization</heading>
6234 There used to be another directory, <file>/etc/rc.boot</file>,
6235 which contained scripts which were run once per machine
6236 boot. This has been deprecated in favour of links from
6237 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6238 described in <ref id="/etc/init.d">. Packages must not
6239 place files in <file>/etc/rc.boot</file>.
6244 <heading>Example</heading>
6247 An example on which you can base your
6248 <file>/etc/init.d</file> scripts is found in
6249 <file>/etc/init.d/skeleton</file>.
6256 <heading>Console messages from <file>init.d</file> scripts</heading>
6259 This section describes the formats to be used for messages
6260 written to standard output by the <file>/etc/init.d</file>
6261 scripts. The intent is to improve the consistency of
6262 Debian's startup and shutdown look and feel. For this
6263 reason, please look very carefully at the details. We want
6264 the messages to have the same format in terms of wording,
6265 spaces, punctuation and case of letters.
6269 Here is a list of overall rules that should be used for
6270 messages generated by <file>/etc/init.d</file> scripts.
6276 The message should fit in one line (fewer than 80
6277 characters), start with a capital letter and end with
6278 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6282 If the script is performing some time consuming task in
6283 the background (not merely starting or stopping a
6284 program, for instance), an ellipsis (three dots:
6285 <tt>...</tt>) should be output to the screen, with no
6286 leading or tailing whitespace or line feeds.
6290 The messages should appear as if the computer is telling
6291 the user what it is doing (politely :-), but should not
6292 mention "it" directly. For example, instead of:
6293 <example compact="compact">
6294 I'm starting network daemons: nfsd mountd.
6296 the message should say
6297 <example compact="compact">
6298 Starting network daemons: nfsd mountd.
6305 <tt>init.d</tt> script should use the following standard
6306 message formats for the situations enumerated below.
6312 <p>When daemons are started</p>
6315 If the script starts one or more daemons, the output
6316 should look like this (a single line, no leading
6318 <example compact="compact">
6319 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6321 The <var>description</var> should describe the
6322 subsystem the daemon or set of daemons are part of,
6323 while <var>daemon-1</var> up to <var>daemon-n</var>
6324 denote each daemon's name (typically the file name of
6329 For example, the output of <file>/etc/init.d/lpd</file>
6331 <example compact="compact">
6332 Starting printer spooler: lpd.
6337 This can be achieved by saying
6338 <example compact="compact">
6339 echo -n "Starting printer spooler: lpd"
6340 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6343 in the script. If there are more than one daemon to
6344 start, the output should look like this:
6345 <example compact="compact">
6346 echo -n "Starting remote file system services:"
6347 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6348 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6349 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6352 This makes it possible for the user to see what is
6353 happening and when the final daemon has been started.
6354 Care should be taken in the placement of white spaces:
6355 in the example above the system administrators can
6356 easily comment out a line if they don't want to start
6357 a specific daemon, while the displayed message still
6363 <p>When a system parameter is being set</p>
6366 If you have to set up different system parameters
6367 during the system boot, you should use this format:
6368 <example compact="compact">
6369 Setting <var>parameter</var> to "<var>value</var>".
6374 You can use a statement such as the following to get
6376 <example compact="compact">
6377 echo "Setting DNS domainname to \"$domainname\"."
6382 Note that the same symbol (<tt>"</tt>) is used for the left
6383 and right quotation marks. A grave accent (<tt>`</tt>) is
6384 not a quote character; neither is an apostrophe
6390 <p>When a daemon is stopped or restarted</p>
6393 When you stop or restart a daemon, you should issue a
6394 message identical to the startup message, except that
6395 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6396 or <tt>Restarting</tt> respectively.
6400 For example, stopping the printer daemon will look like
6402 <example compact="compact">
6403 Stopping printer spooler: lpd.
6409 <p>When something is executed</p>
6412 There are several examples where you have to run a
6413 program at system startup or shutdown to perform a
6414 specific task, for example, setting the system's clock
6415 using <prgn>netdate</prgn> or killing all processes
6416 when the system shuts down. Your message should look
6418 <example compact="compact">
6419 Doing something very useful...done.
6421 You should print the <tt>done.</tt> immediately after
6422 the job has been completed, so that the user is
6423 informed why they have to wait. You can get this
6425 <example compact="compact">
6426 echo -n "Doing something very useful..."
6435 <p>When the configuration is reloaded</p>
6438 When a daemon is forced to reload its configuration
6439 files you should use the following format:
6440 <example compact="compact">
6441 Reloading <var>description</var> configuration...done.
6443 where <var>description</var> is the same as in the
6444 daemon starting message.
6452 <heading>Cron jobs</heading>
6455 Packages must not modify the configuration file
6456 <file>/etc/crontab</file>, and they must not modify the files in
6457 <file>/var/spool/cron/crontabs</file>.</p>
6460 If a package wants to install a job that has to be executed
6461 via cron, it should place a file with the name of the
6462 package in one or more of the following directories:
6463 <example compact="compact">
6469 As these directory names imply, the files within them are
6470 executed on an hourly, daily, weekly, or monthly basis,
6471 respectively. The exact times are listed in
6472 <file>/etc/crontab</file>.</p>
6475 All files installed in any of these directories must be
6476 scripts (e.g., shell scripts or Perl scripts) so that they
6477 can easily be modified by the local system administrator.
6478 In addition, they must be treated as configuration files.
6482 If a certain job has to be executed at some other frequency or
6483 at a specific time, the package should install a file
6484 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6485 same syntax as <file>/etc/crontab</file> and is processed by
6486 <prgn>cron</prgn> automatically. The file must also be
6487 treated as a configuration file. (Note that entries in the
6488 <file>/etc/cron.d</file> directory are not handled by
6489 <prgn>anacron</prgn>. Thus, you should only use this
6490 directory for jobs which may be skipped if the system is not
6494 The scripts or crontab entries in these directories should
6495 check if all necessary programs are installed before they
6496 try to execute them. Otherwise, problems will arise when a
6497 package was removed but not purged since configuration files
6498 are kept on the system in this situation.</p>
6502 <heading>Menus</heading>
6505 The Debian <tt>menu</tt> package provides a standard
6506 interface between packages providing applications and
6507 <em>menu programs</em> (either X window managers or
6508 text-based menu programs such as <prgn>pdmenu</prgn>).
6512 All packages that provide applications that need not be
6513 passed any special command line arguments for normal
6514 operation should register a menu entry for those
6515 applications, so that users of the <tt>menu</tt> package
6516 will automatically get menu entries in their window
6517 managers, as well in shells like <tt>pdmenu</tt>.
6521 Menu entries should follow the current menu policy.
6525 The menu policy can be found in the <tt>menu-policy</tt>
6526 files in the <tt>debian-policy</tt> package.
6527 It is also available from the Debian web mirrors at
6528 <tt><url name="/doc/packaging-manuals/menu-policy/"
6529 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6533 Please also refer to the <em>Debian Menu System</em>
6534 documentation that comes with the <package>menu</package>
6535 package for information about how to register your
6541 <heading>Multimedia handlers</heading>
6544 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6545 is a mechanism for encoding files and data streams and
6546 providing meta-information about them, in particular their
6547 type (e.g. audio or video) and format (e.g. PNG, HTML,
6552 Registration of MIME type handlers allows programs like mail
6553 user agents and web browsers to invoke these handlers to
6554 view, edit or display MIME types they don't support directly.
6558 Packages which provide the ability to view/show/play,
6559 compose, edit or print MIME types should register themselves
6560 as such following the current MIME support policy.
6564 The MIME support policy can be found in the <tt>mime-policy</tt>
6565 files in the <tt>debian-policy</tt> package.
6566 It is also available from the Debian web mirrors at
6567 <tt><url name="/doc/packaging-manuals/mime-policy/"
6568 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6574 <heading>Keyboard configuration</heading>
6577 To achieve a consistent keyboard configuration so that all
6578 applications interpret a keyboard event the same way, all
6579 programs in the Debian distribution must be configured to
6580 comply with the following guidelines.
6584 The following keys must have the specified interpretations:
6587 <tag><tt><--</tt></tag>
6588 <item>delete the character to the left of the cursor</item>
6590 <tag><tt>Delete</tt></tag>
6591 <item>delete the character to the right of the cursor</item>
6593 <tag><tt>Control+H</tt></tag>
6594 <item>emacs: the help prefix</item>
6597 The interpretation of any keyboard events should be
6598 independent of the terminal that is used, be it a virtual
6599 console, an X terminal emulator, an rlogin/telnet session,
6604 The following list explains how the different programs
6605 should be set up to achieve this:
6611 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6615 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6619 X translations are set up to make
6620 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6621 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6622 is the vt220 escape code for the "delete character"
6623 key). This must be done by loading the X resources
6624 using <prgn>xrdb</prgn> on all local X displays, not
6625 using the application defaults, so that the
6626 translation resources used correspond to the
6627 <prgn>xmodmap</prgn> settings.
6631 The Linux console is configured to make
6632 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6633 generate <tt>ESC [ 3 ~</tt>.
6637 X applications are configured so that <tt><</tt>
6638 deletes left, and <tt>Delete</tt> deletes right. Motif
6639 applications already work like this.
6643 Terminals should have <tt>stty erase ^?</tt> .
6647 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6648 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6649 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6653 Emacs is programmed to map <tt>KB_Backspace</tt> or
6654 the <tt>stty erase</tt> character to
6655 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6656 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6657 <tt>^H</tt> to <tt>help</tt> as always.
6661 Other applications use the <tt>stty erase</tt>
6662 character and <tt>kdch1</tt> for the two delete keys,
6663 with ASCII DEL being "delete previous character" and
6664 <tt>kdch1</tt> being "delete character under
6672 This will solve the problem except for the following
6679 Some terminals have a <tt><--</tt> key that cannot
6680 be made to produce anything except <tt>^H</tt>. On
6681 these terminals Emacs help will be unavailable on
6682 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6683 character takes precedence in Emacs, and has been set
6684 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6685 available) can be used instead.
6689 Some operating systems use <tt>^H</tt> for <tt>stty
6690 erase</tt>. However, modern telnet versions and all
6691 rlogin versions propagate <tt>stty</tt> settings, and
6692 almost all UNIX versions honour <tt>stty erase</tt>.
6693 Where the <tt>stty</tt> settings are not propagated
6694 correctly, things can be made to work by using
6695 <tt>stty</tt> manually.
6699 Some systems (including previous Debian versions) use
6700 <prgn>xmodmap</prgn> to arrange for both
6701 <tt><--</tt> and <tt>Delete</tt> to generate
6702 <tt>KB_Delete</tt>. We can change the behavior of
6703 their X clients using the same X resources that we use
6704 to do it for our own clients, or configure our clients
6705 using their resources when things are the other way
6706 around. On displays configured like this
6707 <tt>Delete</tt> will not work, but <tt><--</tt>
6712 Some operating systems have different <tt>kdch1</tt>
6713 settings in their <tt>terminfo</tt> database for
6714 <tt>xterm</tt> and others. On these systems the
6715 <tt>Delete</tt> key will not work correctly when you
6716 log in from a system conforming to our policy, but
6717 <tt><--</tt> will.
6724 <heading>Environment variables</heading>
6727 A program must not depend on environment variables to get
6728 reasonable defaults. (That's because these environment
6729 variables would have to be set in a system-wide
6730 configuration file like <file>/etc/profile</file>, which is not
6731 supported by all shells.)
6735 If a program usually depends on environment variables for its
6736 configuration, the program should be changed to fall back to
6737 a reasonable default configuration if these environment
6738 variables are not present. If this cannot be done easily
6739 (e.g., if the source code of a non-free program is not
6740 available), the program must be replaced by a small
6741 "wrapper" shell script which sets the environment variables
6742 if they are not already defined, and calls the original program.
6746 Here is an example of a wrapper script for this purpose:
6748 <example compact="compact">
6750 BAR=${BAR:-/var/lib/fubar}
6752 exec /usr/lib/foo/foo "$@"
6757 Furthermore, as <file>/etc/profile</file> is a configuration
6758 file of the <prgn>base-files</prgn> package, other packages must
6759 not put any environment variables or other commands into that
6764 <sect id="doc-base">
6765 <heading>Registering Documents using doc-base</heading>
6768 The <package>doc-base</package> package implements a
6769 flexible mechanism for handling and presenting
6770 documentation. The recommended practice is for every Debian
6771 package that provides online documentation (other than just
6772 manual pages) to register these documents with
6773 <package>doc-base</package> by installing a
6774 <package>doc-base</package> control file via the
6775 <prgn/install-docs/ script at installation time and
6776 de-register the manuals again when the package is removed.
6779 Please refer to the documentation that comes with the
6780 <package>doc-base</package> package for information and
6789 <heading>Files</heading>
6792 <heading>Binaries</heading>
6795 Two different packages must not install programs with
6796 different functionality but with the same filenames. (The
6797 case of two programs having the same functionality but
6798 different implementations is handled via "alternatives" or
6799 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6800 <ref id="conflicts"> respectively.) If this case happens,
6801 one of the programs must be renamed. The maintainers should
6802 report this to the <tt>debian-devel</tt> mailing list and
6803 try to find a consensus about which program will have to be
6804 renamed. If a consensus cannot be reached, <em>both</em>
6805 programs must be renamed.
6809 By default, when a package is being built, any binaries
6810 created should include debugging information, as well as
6811 being compiled with optimization. You should also turn on
6812 as many reasonable compilation warnings as possible; this
6813 makes life easier for porters, who can then look at build
6814 logs for possible problems. For the C programming language,
6815 this means the following compilation parameters should be
6817 <example compact="compact">
6819 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6821 INSTALL = install -s # (or use strip on the files in debian/tmp)
6826 Note that by default all installed binaries should be stripped,
6827 either by using the <tt>-s</tt> flag to
6828 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6829 the binaries after they have been copied into
6830 <file>debian/tmp</file> but before the tree is made into a
6835 Although binaries in the build tree should be compiled with
6836 debugging information by default, it can often be difficult to
6837 debug programs if they are also subjected to compiler
6838 optimization. For this reason, it is recommended to support the
6839 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6840 (see <ref id="debianrules-options">). This variable can contain
6841 several flags to change how a package is compiled and built.
6845 It is up to the package maintainer to decide what
6846 compilation options are best for the package. Certain
6847 binaries (such as computationally-intensive programs) will
6848 function better with certain flags (<tt>-O3</tt>, for
6849 example); feel free to use them. Please use good judgment
6850 here. Don't use flags for the sake of it; only use them
6851 if there is good reason to do so. Feel free to override
6852 the upstream author's ideas about which compilation
6853 options are best: they are often inappropriate for our
6859 <sect id="libraries">
6860 <heading>Libraries</heading>
6863 If the package is <strong>architecture: any</strong>, then
6864 the shared library compilation and linking flags must have
6865 <tt>-fPIC</tt>, or the package shall not build on some of
6866 the supported architectures<footnote>
6868 If you are using GCC, <tt>-fPIC</tt> produces code with
6869 relocatable position independent code, which is required for
6870 most architectures to create a shared library, with i386 and
6871 perhaps some others where non position independent code is
6872 permitted in a shared library.
6875 Position independent code may have a performance penalty,
6876 especially on <tt>i386</tt>. However, in most cases the
6877 speed penalty must be measured against the memory wasted on
6878 the few architectures where non position independent code is
6881 </footnote>. Any exception to this rule must be discussed on
6882 the mailing list <em>debian-devel@lists.debian.org</em>, and
6883 a rough consensus obtained. The reasons for not compiling
6884 with <tt>-fPIC</tt> flag must be recorded in the file
6885 <tt>README.Debian</tt>, and care must be taken to either
6886 restrict the architecture or arrange for <tt>-fPIC</tt> to
6887 be used on architectures where it is required.<footnote>
6889 Some of the reasons why this might be required is if the
6890 library contains hand crafted assembly code that is not
6891 relocatable, the speed penalty is excessive for compute
6892 intensive libs, and similar reasons.
6897 As to the static libraries, the common case is not to have
6898 relocatable code, since there is no benefit, unless in specific
6899 cases; therefore the static version must not be compiled
6900 with the <tt>-fPIC</tt> flag. Any exception to this rule
6901 should be discussed on the mailing list
6902 <em>debian-devel@lists.debian.org</em>, and the reasons for
6903 compiling with the <tt>-fPIC</tt> flag must be recorded in
6904 the file <tt>README.Debian</tt>. <footnote>
6906 Some of the reasons for linking static libraries with
6907 the <tt>-fPIC</tt> flag are if, for example, one needs a
6908 Perl API for a library that is under rapid development,
6909 and has an unstable API, so shared libraries are
6910 pointless at this phase of the library's development. In
6911 that case, since Perl needs a library with relocatable
6912 code, it may make sense to create a static library with
6913 relocatable code. Another reason cited is if you are
6914 distilling various libraries into a common shared
6915 library, like <tt>mklibs</tt> does in the Debian
6921 In other words, if both a shared and a static library is
6922 being built, each source unit (<tt>*.c</tt>, for example,
6923 for C files) will need to be compiled twice, for the normal
6927 You must specify the gcc option <tt>-D_REENTRANT</tt>
6928 when building a library (either static or shared) to make
6929 the library compatible with LinuxThreads.
6933 Although not enforced by the build tools, shared libraries
6934 must be linked against all libraries that they use symbols from
6935 in the same way that binaries are. This ensures the correct
6936 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6937 system and guarantees that all libraries can be safely opened
6938 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6939 option <tt>-Wl,-z,defs</tt> when building a shared library.
6940 Since this option enforces symbol resolution at build time,
6941 a missing library reference will be caught early as a fatal
6946 All installed shared libraries should be stripped with
6947 <example compact="compact">
6948 strip --strip-unneeded <var>your-lib</var>
6950 (The option <tt>--strip-unneeded</tt> makes
6951 <prgn>strip</prgn> remove only the symbols which aren't
6952 needed for relocation processing.) Shared libraries can
6953 function perfectly well when stripped, since the symbols for
6954 dynamic linking are in a separate part of the ELF object
6956 You might also want to use the options
6957 <tt>--remove-section=.comment</tt> and
6958 <tt>--remove-section=.note</tt> on both shared libraries
6959 and executables, and <tt>--strip-debug</tt> on static
6965 Note that under some circumstances it may be useful to
6966 install a shared library unstripped, for example when
6967 building a separate package to support debugging.
6971 Shared object files (often <file>.so</file> files) that are not
6972 public libraries, that is, they are not meant to be linked
6973 to by third party executables (binaries of other packages),
6974 should be installed in subdirectories of the
6975 <file>/usr/lib</file> directory. Such files are exempt from the
6976 rules that govern ordinary shared libraries, except that
6977 they must not be installed executable and should be
6979 A common example are the so-called "plug-ins",
6980 internal shared objects that are dynamically loaded by
6981 programs using <manref name="dlopen" section="3">.
6986 An ever increasing number of packages are using
6987 <prgn>libtool</prgn> to do their linking. The latest GNU
6988 libtools (>= 1.3a) can take advantage of the metadata in the
6989 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6990 files). The main advantage of <prgn>libtool</prgn>'s
6991 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6992 store and subsequently access metadata with respect to the
6993 libraries it builds. <prgn>libtool</prgn> will search for
6994 those files, which contain a lot of useful information about
6995 a library (such as library dependency information for static
6996 linking). Also, they're <em>essential</em> for programs
6997 using <tt>libltdl</tt>.<footnote>
6998 Although <prgn>libtool</prgn> is fully capable of
6999 linking against shared libraries which don't have
7000 <tt>.la</tt> files, as it is a mere shell script it can
7001 add considerably to the build time of a
7002 <prgn>libtool</prgn>-using package if that shell script
7003 has to derive all this information from first principles
7004 for each library every time it is linked. With the
7005 advent of <prgn>libtool</prgn> version 1.4 (and to a
7006 lesser extent <prgn>libtool</prgn> version 1.3), the
7007 <file>.la</file> files also store information about
7008 inter-library dependencies which cannot necessarily be
7009 derived after the <file>.la</file> file is deleted.
7014 Packages that use <prgn>libtool</prgn> to create shared
7015 libraries should include the <file>.la</file> files in the
7016 <tt>-dev</tt> package, unless the package relies on
7017 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7018 the <tt>.la</tt> files must go in the run-time library
7023 You must make sure that you use only released versions of
7024 shared libraries to build your packages; otherwise other
7025 users will not be able to run your binaries
7026 properly. Producing source packages that depend on
7027 unreleased compilers is also usually a bad
7034 <heading>Shared libraries</heading>
7036 This section has moved to <ref id="sharedlibs">.
7042 <heading>Scripts</heading>
7045 All command scripts, including the package maintainer
7046 scripts inside the package and used by <prgn>dpkg</prgn>,
7047 should have a <tt>#!</tt> line naming the shell to be used
7052 In the case of Perl scripts this should be
7053 <tt>#!/usr/bin/perl</tt>.
7057 When scripts are installed into a directory in the system
7058 PATH, the script name should not include an extension such
7059 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7060 language currently used to implement it.
7063 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7064 should almost certainly start with <tt>set -e</tt> so that
7065 errors are detected. Every script should use
7066 <tt>set -e</tt> or check the exit status of <em>every</em>
7071 Scripts may assume that <file>/bin/sh</file> implements the
7072 SUSv3 Shell Command Language<footnote>
7073 Single UNIX Specification, version 3, which is also IEEE
7074 1003.1-2004 (POSIX), and is available on the World Wide Web
7075 from <url id="http://www.unix.org/version3/online.html"
7076 name="The Open Group"> after free
7077 registration.</footnote>
7078 plus the following additional features not mandated by
7080 These features are in widespread use in the Linux community
7081 and are implemented in all of bash, dash, and ksh, the most
7082 common shells users may wish to use as <file>/bin/sh</file>.
7085 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7086 must not generate a newline.</item>
7087 <item><tt>test</tt>, if implemented as a shell built-in, must
7088 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7090 <item><tt>local</tt> to create a scoped variable must be
7091 supported, including listing multiple variables in a single
7092 local command and assigning a value to a variable at the
7093 same time as localizing it. <tt>local</tt> may or
7094 may not preserve the variable value from an outer scope if
7095 no assignment is present. Uses such as:
7099 # ... use a, b, c, d ...
7102 must be supported and must set the value of <tt>c</tt> to
7106 If a shell script requires non-SUSv3 features from the shell
7107 interpreter other than those listed above, the appropriate shell
7108 must be specified in the first line of the script (e.g.,
7109 <tt>#!/bin/bash</tt>) and the package must depend on the package
7110 providing the shell (unless the shell package is marked
7111 "Essential", as in the case of <prgn>bash</prgn>).
7115 You may wish to restrict your script to SUSv3 features plus the
7116 above set when possible so that it may use <file>/bin/sh</file>
7117 as its interpreter. If your script works with <prgn>dash</prgn>
7118 (originally called <prgn>ash</prgn>), it probably complies with
7119 the above requirements, but if you are in doubt, use
7120 <file>/bin/bash</file>.
7124 Perl scripts should check for errors when making any
7125 system calls, including <tt>open</tt>, <tt>print</tt>,
7126 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7130 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7131 scripting languages. See <em>Csh Programming Considered
7132 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7133 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7134 If an upstream package comes with <prgn>csh</prgn> scripts
7135 then you must make sure that they start with
7136 <tt>#!/bin/csh</tt> and make your package depend on the
7137 <prgn>c-shell</prgn> virtual package.
7141 Any scripts which create files in world-writeable
7142 directories (e.g., in <file>/tmp</file>) must use a
7143 mechanism which will fail atomically if a file with the same
7144 name already exists.
7148 The Debian base system provides the <prgn>tempfile</prgn>
7149 and <prgn>mktemp</prgn> utilities for use by scripts for
7156 <heading>Symbolic links</heading>
7159 In general, symbolic links within a top-level directory
7160 should be relative, and symbolic links pointing from one
7161 top-level directory into another should be absolute. (A
7162 top-level directory is a sub-directory of the root
7163 directory <file>/</file>.)
7167 In addition, symbolic links should be specified as short as
7168 possible, i.e., link targets like <file>foo/../bar</file> are
7173 Note that when creating a relative link using
7174 <prgn>ln</prgn> it is not necessary for the target of the
7175 link to exist relative to the working directory you're
7176 running <prgn>ln</prgn> from, nor is it necessary to change
7177 directory to the directory where the link is to be made.
7178 Simply include the string that should appear as the target
7179 of the link (this will be a pathname relative to the
7180 directory in which the link resides) as the first argument
7185 For example, in your <prgn>Makefile</prgn> or
7186 <file>debian/rules</file>, you can do things like:
7187 <example compact="compact">
7188 ln -fs gcc $(prefix)/bin/cc
7189 ln -fs gcc debian/tmp/usr/bin/cc
7190 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7191 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7196 A symbolic link pointing to a compressed file should always
7197 have the same file extension as the referenced file. (For
7198 example, if a file <file>foo.gz</file> is referenced by a
7199 symbolic link, the filename of the link has to end with
7200 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7205 <heading>Device files</heading>
7208 Packages must not include device files in the package file
7213 If a package needs any special device files that are not
7214 included in the base system, it must call
7215 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7216 after notifying the user<footnote>
7217 This notification could be done via a (low-priority)
7218 debconf message, or an echo (printf) statement.
7223 Packages must not remove any device files in the
7224 <prgn>postrm</prgn> or any other script. This is left to the
7225 system administrator.
7229 Debian uses the serial devices
7230 <file>/dev/ttyS*</file>. Programs using the old
7231 <file>/dev/cu*</file> devices should be changed to use
7232 <file>/dev/ttyS*</file>.
7236 <sect id="config-files">
7237 <heading>Configuration files</heading>
7240 <heading>Definitions</heading>
7244 <tag>configuration file</tag>
7246 A file that affects the operation of a program, or
7247 provides site- or host-specific information, or
7248 otherwise customizes the behavior of a program.
7249 Typically, configuration files are intended to be
7250 modified by the system administrator (if needed or
7251 desired) to conform to local policy or to provide
7252 more useful site-specific behavior.
7255 <tag><tt>conffile</tt></tag>
7257 A file listed in a package's <tt>conffiles</tt>
7258 file, and is treated specially by <prgn>dpkg</prgn>
7259 (see <ref id="configdetails">).
7265 The distinction between these two is important; they are
7266 not interchangeable concepts. Almost all
7267 <tt>conffile</tt>s are configuration files, but many
7268 configuration files are not <tt>conffiles</tt>.
7272 As noted elsewhere, <file>/etc/init.d</file> scripts,
7273 <file>/etc/default</file> files, scripts installed in
7274 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7275 configuration installed in <file>/etc/cron.d</file> must be
7276 treated as configuration files. In general, any script that
7277 embeds configuration information is de-facto a configuration
7278 file and should be treated as such.
7283 <heading>Location</heading>
7286 Any configuration files created or used by your package
7287 must reside in <file>/etc</file>. If there are several,
7288 consider creating a subdirectory of <file>/etc</file>
7289 named after your package.
7293 If your package creates or uses configuration files
7294 outside of <file>/etc</file>, and it is not feasible to modify
7295 the package to use <file>/etc</file> directly, put the files
7296 in <file>/etc</file> and create symbolic links to those files
7297 from the location that the package requires.
7302 <heading>Behavior</heading>
7305 Configuration file handling must conform to the following
7307 <list compact="compact">
7309 local changes must be preserved during a package
7313 configuration files must be preserved when the
7314 package is removed, and only deleted when the
7321 The easy way to achieve this behavior is to make the
7322 configuration file a <tt>conffile</tt>. This is
7323 appropriate only if it is possible to distribute a default
7324 version that will work for most installations, although
7325 some system administrators may choose to modify it. This
7326 implies that the default version will be part of the
7327 package distribution, and must not be modified by the
7328 maintainer scripts during installation (or at any other
7333 In order to ensure that local changes are preserved
7334 correctly, no package may contain or make hard links to
7335 conffiles.<footnote>
7336 Rationale: There are two problems with hard links.
7337 The first is that some editors break the link while
7338 editing one of the files, so that the two files may
7339 unwittingly become unlinked and different. The second
7340 is that <prgn>dpkg</prgn> might break the hard link
7341 while upgrading <tt>conffile</tt>s.
7346 The other way to do it is via the maintainer scripts. In
7347 this case, the configuration file must not be listed as a
7348 <tt>conffile</tt> and must not be part of the package
7349 distribution. If the existence of a file is required for
7350 the package to be sensibly configured it is the
7351 responsibility of the package maintainer to provide
7352 maintainer scripts which correctly create, update and
7353 maintain the file and remove it on purge. (See <ref
7354 id="maintainerscripts"> for more information.) These
7355 scripts must be idempotent (i.e., must work correctly if
7356 <prgn>dpkg</prgn> needs to re-run them due to errors
7357 during installation or removal), must cope with all the
7358 variety of ways <prgn>dpkg</prgn> can call maintainer
7359 scripts, must not overwrite or otherwise mangle the user's
7360 configuration without asking, must not ask unnecessary
7361 questions (particularly during upgrades), and must
7362 otherwise be good citizens.
7366 The scripts are not required to configure every possible
7367 option for the package, but only those necessary to get
7368 the package running on a given system. Ideally the
7369 sysadmin should not have to do any configuration other
7370 than that done (semi-)automatically by the
7371 <prgn>postinst</prgn> script.
7375 A common practice is to create a script called
7376 <file><var>package</var>-configure</file> and have the
7377 package's <prgn>postinst</prgn> call it if and only if the
7378 configuration file does not already exist. In certain
7379 cases it is useful for there to be an example or template
7380 file which the maintainer scripts use. Such files should
7381 be in <file>/usr/share/<var>package</var></file> or
7382 <file>/usr/lib/<var>package</var></file> (depending on whether
7383 they are architecture-independent or not). There should
7384 be symbolic links to them from
7385 <file>/usr/share/doc/<var>package</var>/examples</file> if
7386 they are examples, and should be perfectly ordinary
7387 <prgn>dpkg</prgn>-handled files (<em>not</em>
7388 configuration files).
7392 These two styles of configuration file handling must
7393 not be mixed, for that way lies madness:
7394 <prgn>dpkg</prgn> will ask about overwriting the file
7395 every time the package is upgraded.
7400 <heading>Sharing configuration files</heading>
7403 Packages which specify the same file as a
7404 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7405 with each other. (This is an instance of the general rule
7406 about not sharing files. Note that neither alternatives
7407 nor diversions are likely to be appropriate in this case;
7408 in particular, <prgn>dpkg</prgn> does not handle diverted
7409 <tt>conffile</tt>s well.)
7413 The maintainer scripts must not alter a <tt>conffile</tt>
7414 of <em>any</em> package, including the one the scripts
7419 If two or more packages use the same configuration file
7420 and it is reasonable for both to be installed at the same
7421 time, one of these packages must be defined as
7422 <em>owner</em> of the configuration file, i.e., it will be
7423 the package which handles that file as a configuration
7424 file. Other packages that use the configuration file must
7425 depend on the owning package if they require the
7426 configuration file to operate. If the other package will
7427 use the configuration file if present, but is capable of
7428 operating without it, no dependency need be declared.
7432 If it is desirable for two or more related packages to
7433 share a configuration file <em>and</em> for all of the
7434 related packages to be able to modify that configuration
7435 file, then the following should be done:
7436 <enumlist compact="compact">
7438 One of the related packages (the "owning" package)
7439 will manage the configuration file with maintainer
7440 scripts as described in the previous section.
7443 The owning package should also provide a program
7444 that the other packages may use to modify the
7448 The related packages must use the provided program
7449 to make any desired modifications to the
7450 configuration file. They should either depend on
7451 the core package to guarantee that the configuration
7452 modifier program is available or accept gracefully
7453 that they cannot modify the configuration file if it
7454 is not. (This is in addition to the fact that the
7455 configuration file may not even be present in the
7462 Sometimes it's appropriate to create a new package which
7463 provides the basic infrastructure for the other packages
7464 and which manages the shared configuration files. (The
7465 <tt>sgml-base</tt> package is a good example.)
7470 <heading>User configuration files ("dotfiles")</heading>
7473 The files in <file>/etc/skel</file> will automatically be
7474 copied into new user accounts by <prgn>adduser</prgn>.
7475 No other program should reference the files in
7476 <file>/etc/skel</file>.
7480 Therefore, if a program needs a dotfile to exist in
7481 advance in <file>$HOME</file> to work sensibly, that dotfile
7482 should be installed in <file>/etc/skel</file> and treated as a
7487 However, programs that require dotfiles in order to
7488 operate sensibly are a bad thing, unless they do create
7489 the dotfiles themselves automatically.
7493 Furthermore, programs should be configured by the Debian
7494 default installation to behave as closely to the upstream
7495 default behavior as possible.
7499 Therefore, if a program in a Debian package needs to be
7500 configured in some way in order to operate sensibly, that
7501 should be done using a site-wide configuration file placed
7502 in <file>/etc</file>. Only if the program doesn't support a
7503 site-wide default configuration and the package maintainer
7504 doesn't have time to add it may a default per-user file be
7505 placed in <file>/etc/skel</file>.
7509 <file>/etc/skel</file> should be as empty as we can make it.
7510 This is particularly true because there is no easy (or
7511 necessarily desirable) mechanism for ensuring that the
7512 appropriate dotfiles are copied into the accounts of
7513 existing users when a package is installed.
7519 <heading>Log files</heading>
7521 Log files should usually be named
7522 <file>/var/log/<var>package</var>.log</file>. If you have many
7523 log files, or need a separate directory for permission
7524 reasons (<file>/var/log</file> is writable only by
7525 <file>root</file>), you should usually create a directory named
7526 <file>/var/log/<var>package</var></file> and place your log
7531 Log files must be rotated occasionally so that they don't
7532 grow indefinitely; the best way to do this is to drop a log
7533 rotation configuration file into the directory
7534 <file>/etc/logrotate.d</file> and use the facilities provided by
7535 logrotate.<footnote>
7537 The traditional approach to log files has been to set up
7538 <em>ad hoc</em> log rotation schemes using simple shell
7539 scripts and cron. While this approach is highly
7540 customizable, it requires quite a lot of sysadmin work.
7541 Even though the original Debian system helped a little
7542 by automatically installing a system which can be used
7543 as a template, this was deemed not enough.
7547 The use of <prgn>logrotate</prgn>, a program developed
7548 by Red Hat, is better, as it centralizes log management.
7549 It has both a configuration file
7550 (<file>/etc/logrotate.conf</file>) and a directory where
7551 packages can drop their individual log rotation
7552 configurations (<file>/etc/logrotate.d</file>).
7555 Here is a good example for a logrotate config
7556 file (for more information see <manref name="logrotate"
7558 <example compact="compact">
7559 /var/log/foo/*.log {
7564 /etc/init.d/foo force-reload
7568 This rotates all files under <file>/var/log/foo</file>, saves 12
7569 compressed generations, and forces the daemon to reload its
7570 configuration information after the log rotation.
7574 Log files should be removed when the package is
7575 purged (but not when it is only removed). This should be
7576 done by the <prgn>postrm</prgn> script when it is called
7577 with the argument <tt>purge</tt> (see <ref
7578 id="removedetails">).
7583 <heading>Permissions and owners</heading>
7586 The rules in this section are guidelines for general use.
7587 If necessary you may deviate from the details below.
7588 However, if you do so you must make sure that what is done
7589 is secure and you should try to be as consistent as possible
7590 with the rest of the system. You should probably also
7591 discuss it on <prgn>debian-devel</prgn> first.
7595 Files should be owned by <tt>root:root</tt>, and made
7596 writable only by the owner and universally readable (and
7597 executable, if appropriate), that is mode 644 or 755.
7601 Directories should be mode 755 or (for group-writability)
7602 mode 2775. The ownership of the directory should be
7603 consistent with its mode: if a directory is mode 2775, it
7604 should be owned by the group that needs write access to
7607 When a package is upgraded, and the owner or permissions
7608 of a file included in the package has changed, dpkg
7609 arranges for the ownership and permissions to be
7610 correctly set upon installation. However, this does not
7611 extend to directories; the permissions and ownership of
7612 directories already on the system does not change on
7613 install or upgrade of packages. This makes sense, since
7614 otherwise common directories like <tt>/usr</tt> would
7615 always be in flux. To correctly change permissions of a
7616 directory the package owns, explicit action is required,
7617 usually in the <tt>postinst</tt> script. Care must be
7618 taken to handle downgrades as well, in that case.
7625 Setuid and setgid executables should be mode 4755 or 2755
7626 respectively, and owned by the appropriate user or group.
7627 They should not be made unreadable (modes like 4711 or
7628 2711 or even 4111); doing so achieves no extra security,
7629 because anyone can find the binary in the freely available
7630 Debian package; it is merely inconvenient. For the same
7631 reason you should not restrict read or execute permissions
7632 on non-set-id executables.
7636 Some setuid programs need to be restricted to particular
7637 sets of users, using file permissions. In this case they
7638 should be owned by the uid to which they are set-id, and by
7639 the group which should be allowed to execute them. They
7640 should have mode 4754; again there is no point in making
7641 them unreadable to those users who must not be allowed to
7646 It is possible to arrange that the system administrator can
7647 reconfigure the package to correspond to their local
7648 security policy by changing the permissions on a binary:
7649 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7650 described below.<footnote>
7651 Ordinary files installed by <prgn>dpkg</prgn> (as
7652 opposed to <tt>conffile</tt>s and other similar objects)
7653 normally have their permissions reset to the distributed
7654 permissions when the package is reinstalled. However,
7655 the use of <prgn>dpkg-statoverride</prgn> overrides this
7656 default behavior. If you use this method, you should
7657 remember to describe <prgn>dpkg-statoverride</prgn> in
7658 the package documentation; being a relatively new
7659 addition to Debian, it is probably not yet well-known.
7661 Another method you should consider is to create a group for
7662 people allowed to use the program(s) and make any setuid
7663 executables executable only by that group.
7667 If you need to create a new user or group for your package
7668 there are two possibilities. Firstly, you may need to
7669 make some files in the binary package be owned by this
7670 user or group, or you may need to compile the user or
7671 group id (rather than just the name) into the binary
7672 (though this latter should be avoided if possible, as in
7673 this case you need a statically allocated id).</p>
7676 If you need a statically allocated id, you must ask for a
7677 user or group id from the <tt>base-passwd</tt> maintainer,
7678 and must not release the package until you have been
7679 allocated one. Once you have been allocated one you must
7680 either make the package depend on a version of the
7681 <tt>base-passwd</tt> package with the id present in
7682 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7683 your package to create the user or group itself with the
7684 correct id (using <tt>adduser</tt>) in its
7685 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7686 the <prgn>postinst</prgn> is to be preferred if it is
7687 possible, otherwise a pre-dependency will be needed on the
7688 <tt>adduser</tt> package.)
7692 On the other hand, the program might be able to determine
7693 the uid or gid from the user or group name at runtime, so
7694 that a dynamically allocated id can be used. In this case
7695 you should choose an appropriate user or group name,
7696 discussing this on <prgn>debian-devel</prgn> and checking
7697 with the <package/base-passwd/ maintainer that it is unique and that
7698 they do not wish you to use a statically allocated id
7699 instead. When this has been checked you must arrange for
7700 your package to create the user or group if necessary using
7701 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7702 <prgn>postinst</prgn> script (again, the latter is to be
7703 preferred if it is possible).
7707 Note that changing the numeric value of an id associated
7708 with a name is very difficult, and involves searching the
7709 file system for all appropriate files. You need to think
7710 carefully whether a static or dynamic id is required, since
7711 changing your mind later will cause problems.
7714 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7716 This section is not intended as policy, but as a
7717 description of the use of <prgn>dpkg-statoverride</prgn>.
7721 If a system administrator wishes to have a file (or
7722 directory or other such thing) installed with owner and
7723 permissions different from those in the distributed Debian
7724 package, they can use the <prgn>dpkg-statoverride</prgn>
7725 program to instruct <prgn>dpkg</prgn> to use the different
7726 settings every time the file is installed. Thus the
7727 package maintainer should distribute the files with their
7728 normal permissions, and leave it for the system
7729 administrator to make any desired changes. For example, a
7730 daemon which is normally required to be setuid root, but
7731 in certain situations could be used without being setuid,
7732 should be installed setuid in the <tt>.deb</tt>. Then the
7733 local system administrator can change this if they wish.
7734 If there are two standard ways of doing it, the package
7735 maintainer can use <tt>debconf</tt> to find out the
7736 preference, and call <prgn>dpkg-statoverride</prgn> in the
7737 maintainer script if necessary to accommodate the system
7738 administrator's choice. Care must be taken during
7739 upgrades to not override an existing setting.
7743 Given the above, <prgn>dpkg-statoverride</prgn> is
7744 essentially a tool for system administrators and would not
7745 normally be needed in the maintainer scripts. There is
7746 one type of situation, though, where calls to
7747 <prgn>dpkg-statoverride</prgn> would be needed in the
7748 maintainer scripts, and that involves packages which use
7749 dynamically allocated user or group ids. In such a
7750 situation, something like the following idiom can be very
7751 helpful in the package's <prgn>postinst</prgn>, where
7752 <tt>sysuser</tt> is a dynamically allocated id:
7754 for i in /usr/bin/foo /usr/sbin/bar
7756 # only do something when no setting exists
7757 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7759 #include: debconf processing, question about foo and bar
7760 if [ "$RET" = "true" ] ; then
7761 dpkg-statoverride --update --add sysuser root 4755 $i
7766 The corresponding <tt>dpkg-statoverride --remove</tt>
7767 calls can then be made unconditionally when the package is
7775 <chapt id="customized-programs">
7776 <heading>Customized programs</heading>
7778 <sect id="arch-spec">
7779 <heading>Architecture specification strings</heading>
7782 If a program needs to specify an <em>architecture specification
7783 string</em> in some place, it should select one of the
7784 strings provided by <tt>dpkg-architecture -L</tt>. The
7785 strings are in the format
7786 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7787 is sometimes elided, as when the OS is Linux.<footnote>
7788 <p>Currently, the strings are:
7789 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7790 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7791 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7792 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7793 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7794 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7795 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7796 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7797 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7798 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7799 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7800 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7801 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7802 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7803 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7804 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7805 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7806 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7807 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7808 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7809 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7810 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7811 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7812 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7813 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7814 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7815 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7816 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7817 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7818 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7819 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7820 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7821 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7822 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7823 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7824 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7825 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7831 Note that we don't want to use
7832 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7833 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7834 since this would make our programs incompatible with other
7835 Linux distributions. We also don't use something like
7836 <tt><var>arch</var>-unknown-linux</tt>, since the
7837 <tt>unknown</tt> does not look very good.
7842 <heading>Daemons</heading>
7845 The configuration files <file>/etc/services</file>,
7846 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7847 by the <prgn>netbase</prgn> package and must not be modified
7852 If a package requires a new entry in one of these files, the
7853 maintainer should get in contact with the
7854 <prgn>netbase</prgn> maintainer, who will add the entries
7855 and release a new version of the <prgn>netbase</prgn>
7860 The configuration file <file>/etc/inetd.conf</file> must not be
7861 modified by the package's scripts except via the
7862 <prgn>update-inetd</prgn> script or the
7863 <file>DebianNet.pm</file> Perl module. See their documentation
7864 for details on how to add entries.
7868 If a package wants to install an example entry into
7869 <file>/etc/inetd.conf</file>, the entry must be preceded with
7870 exactly one hash character (<tt>#</tt>). Such lines are
7871 treated as "commented out by user" by the
7872 <prgn>update-inetd</prgn> script and are not changed or
7873 activated during package updates.
7878 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7882 Some programs need to create pseudo-ttys. This should be done
7883 using Unix98 ptys if the C library supports it. The resulting
7884 program must not be installed setuid root, unless that
7885 is required for other functionality.
7889 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7890 <file>/var/log/lastlog</file> must be installed writable by
7891 group <tt>utmp</tt>. Programs which need to modify those
7892 files must be installed setgid <tt>utmp</tt>.
7897 <heading>Editors and pagers</heading>
7900 Some programs have the ability to launch an editor or pager
7901 program to edit or display a text document. Since there are
7902 lots of different editors and pagers available in the Debian
7903 distribution, the system administrator and each user should
7904 have the possibility to choose their preferred editor and
7909 In addition, every program should choose a good default
7910 editor/pager if none is selected by the user or system
7915 Thus, every program that launches an editor or pager must
7916 use the EDITOR or PAGER environment variable to determine
7917 the editor or pager the user wishes to use. If these
7918 variables are not set, the programs <file>/usr/bin/editor</file>
7919 and <file>/usr/bin/pager</file> should be used, respectively.
7923 These two files are managed through the <prgn>dpkg</prgn>
7924 "alternatives" mechanism. Thus every package providing an
7925 editor or pager must call the
7926 <prgn>update-alternatives</prgn> script to register these
7931 If it is very hard to adapt a program to make use of the
7932 EDITOR or PAGER variables, that program may be configured to
7933 use <file>/usr/bin/sensible-editor</file> and
7934 <file>/usr/bin/sensible-pager</file> as the editor or pager
7935 program respectively. These are two scripts provided in the
7936 Debian base system that check the EDITOR and PAGER variables
7937 and launch the appropriate program, and fall back to
7938 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7939 variable is not set.
7943 A program may also use the VISUAL environment variable to
7944 determine the user's choice of editor. If it exists, it
7945 should take precedence over EDITOR. This is in fact what
7946 <file>/usr/bin/sensible-editor</file> does.
7950 It is not required for a package to depend on
7951 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7952 package to provide such virtual packages.<footnote>
7953 The Debian base system already provides an editor and a
7959 <sect id="web-appl">
7960 <heading>Web servers and applications</heading>
7963 This section describes the locations and URLs that should
7964 be used by all web servers and web applications in the
7971 Cgi-bin executable files are installed in the
7973 <example compact="compact">
7974 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7976 and should be referred to as
7977 <example compact="compact">
7978 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7984 <p>Access to HTML documents</p>
7987 HTML documents for a package are stored in
7988 <file>/usr/share/doc/<var>package</var></file>
7989 and can be referred to as
7990 <example compact="compact">
7991 http://localhost/doc/<var>package</var>/<var>filename</var>
7996 The web server should restrict access to the document
7997 tree so that only clients on the same host can read
7998 the documents. If the web server does not support such
7999 access controls, then it should not provide access at
8000 all, or ask about providing access during installation.
8005 <p>Access to images</p>
8007 It is recommended that images for a package be stored
8008 in <tt>/usr/share/images/<var>package</var></tt> and
8009 may be referred to through an alias <tt>/images/</tt>
8012 http://localhost/images/<package>/<filename>
8019 <p>Web Document Root</p>
8022 Web Applications should try to avoid storing files in
8023 the Web Document Root. Instead they should use the
8024 /usr/share/doc/<var>package</var> directory for
8025 documents and register the Web Application via the
8026 <package>doc-base</package> package. If access to the
8027 web document root is unavoidable then use
8028 <example compact="compact">
8031 as the Document Root. This might be just a symbolic
8032 link to the location where the system administrator
8033 has put the real document root.
8036 <item><p>Providing httpd and/or httpd-cgi</p>
8038 All web servers should provide the virtual package
8039 <tt>httpd</tt>. If a web server has CGI support it should
8040 provide <tt>httpd-cgi</tt> additionally.
8043 All web applications which do not contain CGI scripts should
8044 depend on <tt>httpd</tt>, all those web applications which
8045 <tt>do</tt> contain CGI scripts, should depend on
8053 <sect id="mail-transport-agents">
8054 <heading>Mail transport, delivery and user agents</heading>
8057 Debian packages which process electronic mail, whether mail
8058 user agents (MUAs) or mail transport agents (MTAs), must
8059 ensure that they are compatible with the configuration
8060 decisions below. Failure to do this may result in lost
8061 mail, broken <tt>From:</tt> lines, and other serious brain
8066 The mail spool is <file>/var/mail</file> and the interface to
8067 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8068 the FHS). On older systems, the mail spool may be
8069 physically located in <file>/var/spool/mail</file>, but all
8070 access to the mail spool should be via the
8071 <file>/var/mail</file> symlink. The mail spool is part of the
8072 base system and not part of the MTA package.
8076 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8077 programs (such as IMAP daemons) must lock the mailbox in an
8078 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8079 be combined with dot locking. To avoid deadlocks, a program
8080 should use <tt>fcntl()</tt> first and dot locking after
8081 this, or alternatively implement the two locking methods in
8082 a non blocking way<footnote>
8083 If it is not possible to establish both locks, the
8084 system shouldn't wait for the second lock to be
8085 established, but remove the first lock, wait a (random)
8086 time, and start over locking again.
8087 </footnote>. Using the functions <tt>maillock</tt> and
8088 <tt>mailunlock</tt> provided by the
8089 <tt>liblockfile*</tt><footnote>
8090 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8091 to use these functions.
8092 </footnote> packages is the recommended way to realize this.
8096 Mailboxes are generally either mode 600 and owned by
8097 <var>user</var> or mode 660 and owned by
8098 <tt><var>user</var>:mail</tt><footnote>
8099 There are two traditional permission schemes for mail spools:
8100 mode 600 with all mail delivery done by processes running as
8101 the destination user, or mode 660 and owned by group mail with
8102 mail delivery done by a process running as a system user in
8103 group mail. Historically, Debian required mode 660 mail
8104 spools to enable the latter model, but that model has become
8105 increasingly uncommon and the principle of least privilege
8106 indicates that mail systems that use the first model should
8107 use permissions of 600. If delivery to programs is permitted,
8108 it's easier to keep the mail system secure if the delivery
8109 agent runs as the destination user. Debian Policy therefore
8110 permits either scheme.
8111 </footnote>. The local system administrator may choose a
8112 different permission scheme; packages should not make
8113 assumptions about the permission and ownership of mailboxes
8114 unless required (such as when creating a new mailbox). A MUA
8115 may remove a mailbox (unless it has nonstandard permissions) in
8116 which case the MTA or another MUA must recreate it if needed.
8120 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8121 be setgid mail to do the locking mentioned above (and
8122 must obviously avoid accessing other users' mailboxes
8123 using this privilege).</p>
8126 <file>/etc/aliases</file> is the source file for the system mail
8127 aliases (e.g., postmaster, usenet, etc.), it is the one
8128 which the sysadmin and <prgn>postinst</prgn> scripts may
8129 edit. After <file>/etc/aliases</file> is edited the program or
8130 human editing it must call <prgn>newaliases</prgn>. All MTA
8131 packages must come with a <prgn>newaliases</prgn> program,
8132 even if it does nothing, but older MTA packages did not do
8133 this so programs should not fail if <prgn>newaliases</prgn>
8134 cannot be found. Note that because of this, all MTA
8135 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8136 <tt>Replaces: mail-transport-agent</tt> control file
8141 The convention of writing <tt>forward to
8142 <var>address</var></tt> in the mailbox itself is not
8143 supported. Use a <tt>.forward</tt> file instead.</p>
8146 The <prgn>rmail</prgn> program used by UUCP
8147 for incoming mail should be <file>/usr/sbin/rmail</file>.
8148 Likewise, <prgn>rsmtp</prgn>, for receiving
8149 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8153 If your package needs to know what hostname to use on (for
8154 example) outgoing news and mail messages which are generated
8155 locally, you should use the file <file>/etc/mailname</file>. It
8156 will contain the portion after the username and <tt>@</tt>
8157 (at) sign for email addresses of users on the machine
8158 (followed by a newline).
8162 Such a package should check for the existence of this file
8163 when it is being configured. If it exists, it should be
8164 used without comment, although an MTA's configuration script
8165 may wish to prompt the user even if it finds that this file
8166 exists. If the file does not exist, the package should
8167 prompt the user for the value (preferably using
8168 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8169 as well as using it in the package's configuration. The
8170 prompt should make it clear that the name will not just be
8171 used by that package. For example, in this situation the
8172 <tt>inn</tt> package could say something like:
8173 <example compact="compact">
8174 Please enter the "mail name" of your system. This is the
8175 hostname portion of the address to be shown on outgoing
8176 news and mail messages. The default is
8177 <var>syshostname</var>, your system's host name. Mail
8178 name ["<var>syshostname</var>"]:
8180 where <var>syshostname</var> is the output of <tt>hostname
8186 <heading>News system configuration</heading>
8189 All the configuration files related to the NNTP (news)
8190 servers and clients should be located under
8191 <file>/etc/news</file>.</p>
8194 There are some configuration issues that apply to a number
8195 of news clients and server packages on the machine. These
8199 <tag><file>/etc/news/organization</file></tag>
8201 A string which should appear as the
8202 organization header for all messages posted
8203 by NNTP clients on the machine
8206 <tag><file>/etc/news/server</file></tag>
8208 Contains the FQDN of the upstream NNTP
8209 server, or localhost if the local machine is
8214 Other global files may be added as required for cross-package news
8221 <heading>Programs for the X Window System</heading>
8224 <heading>Providing X support and package priorities</heading>
8227 Programs that can be configured with support for the X
8228 Window System must be configured to do so and must declare
8229 any package dependencies necessary to satisfy their
8230 runtime requirements when using the X Window System. If
8231 such a package is of higher priority than the X packages
8232 on which it depends, it is required that either the
8233 X-specific components be split into a separate package, or
8234 that an alternative version of the package, which includes
8235 X support, be provided, or that the package's priority be
8241 <heading>Packages providing an X server</heading>
8244 Packages that provide an X server that, directly or
8245 indirectly, communicates with real input and display
8246 hardware should declare in their control data that they
8247 provide the virtual package <tt>xserver</tt>.<footnote>
8248 This implements current practice, and provides an
8249 actual policy for usage of the <tt>xserver</tt>
8250 virtual package which appears in the virtual packages
8251 list. In a nutshell, X servers that interface
8252 directly with the display and input hardware or via
8253 another subsystem (e.g., GGI) should provide
8254 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8255 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8261 <heading>Packages providing a terminal emulator</heading>
8264 Packages that provide a terminal emulator for the X Window
8265 System which meet the criteria listed below should declare
8266 in their control data that they provide the virtual
8267 package <tt>x-terminal-emulator</tt>. They should also
8268 register themselves as an alternative for
8269 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8274 To be an <tt>x-terminal-emulator</tt>, a program must:
8275 <list compact="compact">
8277 Be able to emulate a DEC VT100 terminal, or a
8278 compatible terminal.
8282 Support the command-line option <tt>-e
8283 <var>command</var></tt>, which creates a new
8284 terminal window<footnote>
8285 "New terminal window" does not necessarily mean
8286 a new top-level X window directly parented by
8287 the window manager; it could, if the terminal
8288 emulator application were so coded, be a new
8289 "view" in a multiple-document interface (MDI).
8291 and runs the specified <var>command</var>,
8292 interpreting the entirety of the rest of the command
8293 line as a command to pass straight to exec, in the
8294 manner that <tt>xterm</tt> does.
8298 Support the command-line option <tt>-T
8299 <var>title</var></tt>, which creates a new terminal
8300 window with the window title <var>title</var>.
8307 <heading>Packages providing a window manager</heading>
8310 Packages that provide a window manager should declare in
8311 their control data that they provide the virtual package
8312 <tt>x-window-manager</tt>. They should also register
8313 themselves as an alternative for
8314 <file>/usr/bin/x-window-manager</file>, with a priority
8315 calculated as follows:
8316 <list compact="compact">
8318 Start with a priority of 20.
8322 If the window manager supports the Debian menu
8323 system, add 20 points if this support is available
8324 in the package's default configuration (i.e., no
8325 configuration files belonging to the system or user
8326 have to be edited to activate the feature); if
8327 configuration files must be modified, add only 10
8333 If the window manager complies with <url
8334 id="http://www.freedesktop.org/Standards/wm-spec"
8335 name="The Window Manager Specification Project">,
8336 written by the <url id="http://www.freedesktop.org/"
8337 name="Free Desktop Group">, add 40 points.
8341 If the window manager permits the X session to be
8342 restarted using a <em>different</em> window manager
8343 (without killing the X server) in its default
8344 configuration, add 10 points; otherwise add none.
8351 <heading>Packages providing fonts</heading>
8354 Packages that provide fonts for the X Window
8356 For the purposes of Debian Policy, a "font for the X
8357 Window System" is one which is accessed via X protocol
8358 requests. Fonts for the Linux console, for PostScript
8359 renderer, or any other purpose, do not fit this
8360 definition. Any tool which makes such fonts available
8361 to the X Window System, however, must abide by this
8364 must do a number of things to ensure that they are both
8365 available without modification of the X or font server
8366 configuration, and that they do not corrupt files used by
8367 other font packages to register information about
8371 Fonts of any type supported by the X Window System
8372 must be in a separate binary package from any
8373 executables, libraries, or documentation (except
8374 that specific to the fonts shipped, such as their
8375 license information). If one or more of the fonts
8376 so packaged are necessary for proper operation of
8377 the package with which they are associated the font
8378 package may be Recommended; if the fonts merely
8379 provide an enhancement, a Suggests relationship may
8380 be used. Packages must not Depend on font
8382 This is because the X server may retrieve fonts
8383 from the local file system or over the network
8384 from an X font server; the Debian package system
8385 is empowered to deal only with the local
8391 BDF fonts must be converted to PCF fonts with the
8392 <prgn>bdftopcf</prgn> utility (available in the
8393 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8394 placed in a directory that corresponds to their
8396 <list compact="compact">
8398 100 dpi fonts must be placed in
8399 <file>/usr/share/fonts/X11/100dpi/</file>.
8403 75 dpi fonts must be placed in
8404 <file>/usr/share/fonts/X11/75dpi/</file>.
8408 Character-cell fonts, cursor fonts, and other
8409 low-resolution fonts must be placed in
8410 <file>/usr/share/fonts/X11/misc/</file>.
8416 Type 1 fonts must be placed in
8417 <file>/usr/share/fonts/X11/Type1/</file>. If font
8418 metric files are available, they must be placed here
8423 Subdirectories of <file>/usr/share/fonts/X11/</file>
8424 other than those listed above must be neither
8425 created nor used. (The <file>PEX</file>, <file>CID</file>,
8426 <file>Speedo</file>, and <file>cyrillic</file> directories
8427 are excepted for historical reasons, but installation of
8428 files into these directories remains discouraged.)
8432 Font packages may, instead of placing files directly
8433 in the X font directories listed above, provide
8434 symbolic links in that font directory pointing to
8435 the files' actual location in the filesystem. Such
8436 a location must comply with the FHS.
8440 Font packages should not contain both 75dpi and
8441 100dpi versions of a font. If both are available,
8442 they should be provided in separate binary packages
8443 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8444 the names of the packages containing the
8445 corresponding fonts.
8449 Fonts destined for the <file>misc</file> subdirectory
8450 should not be included in the same package as 75dpi
8451 or 100dpi fonts; instead, they should be provided in
8452 a separate package with <tt>-misc</tt> appended to
8457 Font packages must not provide the files
8458 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8459 <file>fonts.scale</file> in a font directory:
8462 <file>fonts.dir</file> files must not be provided at all.
8466 <file>fonts.alias</file> and <file>fonts.scale</file>
8467 files, if needed, should be provided in the
8469 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8470 where <var>fontdir</var> is the name of the
8472 <file>/usr/share/fonts/X11/</file> where the
8473 package's corresponding fonts are stored
8474 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8475 <var>package</var> is the name of the package
8476 that provides these fonts, and
8477 <var>extension</var> is either <tt>scale</tt>
8478 or <tt>alias</tt>, whichever corresponds to
8485 Font packages must declare a dependency on
8486 <tt>xfonts-utils</tt> in their control
8491 Font packages that provide one or more
8492 <file>fonts.scale</file> files as described above must
8493 invoke <prgn>update-fonts-scale</prgn> on each
8494 directory into which they installed fonts
8495 <em>before</em> invoking
8496 <prgn>update-fonts-dir</prgn> on that directory.
8497 This invocation must occur in both the
8498 <prgn>postinst</prgn> (for all arguments) and
8499 <prgn>postrm</prgn> (for all arguments except
8500 <tt>upgrade</tt>) scripts.
8504 Font packages that provide one or more
8505 <file>fonts.alias</file> files as described above must
8506 invoke <prgn>update-fonts-alias</prgn> on each
8507 directory into which they installed fonts. This
8508 invocation must occur in both the
8509 <prgn>postinst</prgn> (for all arguments) and
8510 <prgn>postrm</prgn> (for all arguments except
8511 <tt>upgrade</tt>) scripts.
8515 Font packages must invoke
8516 <prgn>update-fonts-dir</prgn> on each directory into
8517 which they installed fonts. This invocation must
8518 occur in both the <prgn>postinst</prgn> (for all
8519 arguments) and <prgn>postrm</prgn> (for all
8520 arguments except <tt>upgrade</tt>) scripts.
8524 Font packages must not provide alias names for the
8525 fonts they include which collide with alias names
8526 already in use by fonts already packaged.
8530 Font packages must not provide fonts with the same
8531 XLFD registry name as another font already packaged.
8538 <heading>Application defaults files</heading>
8541 Application defaults files must be installed in the
8542 directory <file>/etc/X11/app-defaults/</file> (use of a
8543 localized subdirectory of <file>/etc/X11/</file> as described
8544 in the <em>X Toolkit Intrinsics - C Language
8545 Interface</em> manual is also permitted). They must be
8546 registered as <tt>conffile</tt>s or handled as
8547 configuration files.
8551 Customization of programs' X resources may also be
8552 supported with the provision of a file with the same name
8553 as that of the package placed in the
8554 <file>/etc/X11/Xresources/</file> directory, which must
8555 registered as a <tt>conffile</tt> or handled as a
8556 configuration file.<footnote>
8557 Note that this mechanism is not the same as using
8558 app-defaults; app-defaults are tied to the client
8559 binary on the local file system, whereas X resources
8560 are stored in the X server and affect all connecting
8567 <heading>Installation directory issues</heading>
8570 Historically, packages using the X Window System used a
8571 separate set of installation directories from other packages.
8572 This practice has been discontinued and packages using the X
8573 Window System should now generally be installed in the same
8574 directories as any other package. Specifically, packages must
8575 not install files under the <file>/usr/X11R6/</file> directory
8576 and the <file>/usr/X11R6/</file> directory hierarchy should be
8577 regarded as obsolete.
8581 Include files previously installed under
8582 <file>/usr/X11R6/include/X11/</file> should be installed into
8583 <file>/usr/include/X11/</file>. For files previously
8584 installed into subdirectories of
8585 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8586 determine if subdirectories of <file>/usr/lib/</file> and
8587 <file>/usr/share/</file> can be used. If not, a subdirectory
8588 of <file>/usr/lib/X11/</file> should be used.
8592 Configuration files for window, display, or session managers
8593 or other applications that are tightly integrated with the X
8594 Window System may be placed in a subdirectory
8595 of <file>/etc/X11/</file> corresponding to the package name.
8596 Other X Window System applications should use
8597 the <file>/etc/</file> directory unless otherwise mandated by
8598 policy (such as for <ref id="appdefaults">).
8603 <heading>The OSF/Motif and OpenMotif libraries</heading>
8606 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8607 OpenMotif libraries</em><footnote>
8608 OSF/Motif and OpenMotif are collectively referred to as
8609 "Motif" in this policy document.
8611 should be compiled against and tested with LessTif (a free
8612 re-implementation of Motif) instead. If the maintainer
8613 judges that the program or programs do not work
8614 sufficiently well with LessTif to be distributed and
8615 supported, but do so when compiled against Motif, then two
8616 versions of the package should be created; one linked
8617 statically against Motif and with <tt>-smotif</tt>
8618 appended to the package name, and one linked dynamically
8619 against Motif and with <tt>-dmotif</tt> appended to the
8624 Both Motif-linked versions are dependent
8625 upon non-DFSG-compliant software and thus cannot be
8626 uploaded to the <em>main</em> distribution; if the
8627 software is itself DFSG-compliant it may be uploaded to
8628 the <em>contrib</em> distribution. While known existing
8629 versions of Motif permit unlimited redistribution of
8630 binaries linked against the library (whether statically or
8631 dynamically), it is the package maintainer's
8632 responsibility to determine whether this is permitted by
8633 the license of the copy of Motif in their possession.
8639 <heading>Perl programs and modules</heading>
8642 Perl programs and modules should follow the current Perl policy.
8646 The Perl policy can be found in the <tt>perl-policy</tt>
8647 files in the <tt>debian-policy</tt> package.
8648 It is also available from the Debian web mirrors at
8649 <tt><url name="/doc/packaging-manuals/perl-policy/"
8650 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8655 <heading>Emacs lisp programs</heading>
8658 Please refer to the "Debian Emacs Policy" for details of how to
8659 package emacs lisp programs.
8663 The Emacs policy is available in
8664 <file>debian-emacs-policy.gz</file> of the
8665 <package>emacsen-common</package> package.
8666 It is also available from the Debian web mirrors at
8667 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8668 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8673 <heading>Games</heading>
8676 The permissions on <file>/var/games</file> are mode 755, owner
8677 <tt>root</tt> and group <tt>root</tt>.
8681 Each game decides on its own security policy.</p>
8684 Games which require protected, privileged access to
8685 high-score files, saved games, etc., may be made
8686 set-<em>group</em>-id (mode 2755) and owned by
8687 <tt>root:games</tt>, and use files and directories with
8688 appropriate permissions (770 <tt>root:games</tt>, for
8689 example). They must not be made
8690 set-<em>user</em>-id, as this causes security problems. (If
8691 an attacker can subvert any set-user-id game they can
8692 overwrite the executable of any other, causing other players
8693 of these games to run a Trojan horse program. With a
8694 set-group-id game the attacker only gets access to less
8695 important game data, and if they can get at the other
8696 players' accounts at all it will take considerably more
8700 Some packages, for example some fortune cookie programs, are
8701 configured by the upstream authors to install with their
8702 data files or other static information made unreadable so
8703 that they can only be accessed through set-id programs
8704 provided. You should not do this in a Debian package: anyone can
8705 download the <file>.deb</file> file and read the data from it,
8706 so there is no point making the files unreadable. Not
8707 making the files unreadable also means that you don't have
8708 to make so many programs set-id, which reduces the risk of a
8712 As described in the FHS, binaries of games should be
8713 installed in the directory <file>/usr/games</file>. This also
8714 applies to games that use the X Window System. Manual pages
8715 for games (X and non-X games) should be installed in
8716 <file>/usr/share/man/man6</file>.</p>
8722 <heading>Documentation</heading>
8725 <heading>Manual pages</heading>
8728 You should install manual pages in <prgn>nroff</prgn> source
8729 form, in appropriate places under <file>/usr/share/man</file>.
8730 You should only use sections 1 to 9 (see the FHS for more
8731 details). You must not install a pre-formatted "cat page".
8735 Each program, utility, and function should have an
8736 associated manual page included in the same package. It is
8737 suggested that all configuration files also have a manual
8738 page included as well. Manual pages for protocols and other
8739 auxiliary things are optional.
8743 If no manual page is available, this is considered as a bug
8744 and should be reported to the Debian Bug Tracking System (the
8745 maintainer of the package is allowed to write this bug report
8746 themselves, if they so desire). Do not close the bug report
8747 until a proper man page is available.<footnote>
8748 It is not very hard to write a man page. See the
8749 <url id="http://www.schweikhardt.net/man_page_howto.html"
8750 name="Man-Page-HOWTO">,
8751 <manref name="man" section="7">, the examples
8752 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8753 the helper programs <prgn>help2man</prgn>, or the
8754 directory <file>/usr/share/doc/man-db/examples</file>.
8759 You may forward a complaint about a missing man page to the
8760 upstream authors, and mark the bug as forwarded in the
8761 Debian bug tracking system. Even though the GNU Project do
8762 not in general consider the lack of a man page to be a bug,
8763 we do; if they tell you that they don't consider it a bug
8764 you should leave the bug in our bug tracking system open
8769 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8773 If one man page needs to be accessible via several names it
8774 is better to use a symbolic link than the <file>.so</file>
8775 feature, but there is no need to fiddle with the relevant
8776 parts of the upstream source to change from <file>.so</file> to
8777 symlinks: don't do it unless it's easy. You should not
8778 create hard links in the manual page directories, nor put
8779 absolute filenames in <file>.so</file> directives. The filename
8780 in a <file>.so</file> in a man page should be relative to the
8781 base of the man page tree (usually
8782 <file>/usr/share/man</file>). If you do not create any links
8783 (whether symlinks, hard links, or <tt>.so</tt> directives)
8784 in the file system to the alternate names of the man page,
8785 then you should not rely on <prgn>man</prgn> finding your
8786 man page under those names based solely on the information in
8787 the man page's header.<footnote>
8788 Supporting this in <prgn>man</prgn> often requires
8789 unreasonable processing time to find a manual page or to
8790 report that none exists, and moves knowledge into man's
8791 database that would be better left in the file system.
8792 This support is therefore deprecated and will cease to
8793 be present in the future.
8798 Manual pages in locale-specific subdirectories of
8799 <file>/usr/share/man</file> should use either UTF-8 or the usual
8800 legacy encoding for that language (normally the one corresponding
8801 to the shortest relevant locale name in
8802 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8803 <file>/usr/share/man/fr</file> should use either UTF-8 or
8804 ISO-8859-1.<footnote>
8805 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8806 use. In future, all manual pages will be required to use
8812 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8813 included in the subdirectory name unless it indicates a
8814 significant difference in the language, as this excludes
8815 speakers of the language in other countries.<footnote>
8816 At the time of writing, Chinese and Portuguese are the main
8817 languages with such differences, so <file>pt_BR</file>,
8818 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8823 Due to limitations in current implementations, all characters
8824 in the manual page source should be representable in the usual
8825 legacy encoding for that language, even if the file is
8826 actually encoded in UTF-8. Safe alternative ways to write many
8827 characters outside that range may be found in
8828 <manref name="groff_char" section="7">.
8832 If a localized version of a manual page is provided, it should
8833 either be up-to-date or it should be obvious to the reader that
8834 it is outdated and the original manual page should be used
8835 instead. This can be done either by a note at the beginning of
8836 the manual page or by showing the missing or changed portions in
8837 the original language instead of the target language.
8842 <heading>Info documents</heading>
8845 Info documents should be installed in <file>/usr/share/info</file>.
8846 They should be compressed with <tt>gzip -9</tt>.
8850 Your package should call <prgn>install-info</prgn> to update
8851 the Info <file>dir</file> file in its <prgn>postinst</prgn>
8852 script when called with a <tt>configure</tt> argument, for
8854 <example compact="compact">
8855 install-info --quiet --section Development Development \
8856 /usr/share/info/foobar.info
8860 It is a good idea to specify a section for the location of
8861 your program; this is done with the <tt>--section</tt>
8862 switch. To determine which section to use, you should look
8863 at <file>/usr/share/info/dir</file> on your system and choose the most
8864 relevant (or create a new section if none of the current
8865 sections are relevant). Note that the <tt>--section</tt>
8866 flag takes two arguments; the first is a regular expression
8867 to match (case-insensitively) against an existing section,
8868 the second is used when creating a new one.</p>
8871 You should remove the entries in the <prgn>prerm</prgn>
8872 script when called with a <tt>remove</tt> argument:
8873 <example compact="compact">
8874 install-info --quiet --remove /usr/share/info/foobar.info
8878 If <prgn>install-info</prgn> cannot find a description entry
8879 in the Info file you must supply one. See <manref
8880 name="install-info" section="8"> for details.</p>
8884 <heading>Additional documentation</heading>
8887 Any additional documentation that comes with the package may
8888 be installed at the discretion of the package maintainer.
8889 Plain text documentation should be installed in the directory
8890 <file>/usr/share/doc/<var>package</var></file>, where
8891 <var>package</var> is the name of the package, and
8892 compressed with <tt>gzip -9</tt> unless it is small.
8896 If a package comes with large amounts of documentation which
8897 many users of the package will not require you should create
8898 a separate binary package to contain it, so that it does not
8899 take up disk space on the machines of users who do not need
8900 or want it installed.</p>
8903 It is often a good idea to put text information files
8904 (<file>README</file>s, changelogs, and so forth) that come with
8905 the source package in <file>/usr/share/doc/<var>package</var></file>
8906 in the binary package. However, you don't need to install
8907 the instructions for building and installing the package, of
8911 Packages must not require the existence of any files in
8912 <file>/usr/share/doc/</file> in order to function
8914 The system administrator should be able to
8915 delete files in <file>/usr/share/doc/</file> without causing
8916 any programs to break.
8918 Any files that are referenced by programs but are also
8919 useful as stand alone documentation should be installed under
8920 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8921 <file>/usr/share/doc/<var>package</var></file>.
8925 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8926 link to another directory in <file>/usr/share/doc</file> only if
8927 the two packages both come from the same source and the
8928 first package Depends on the second.<footnote>
8930 Please note that this does not override the section on
8931 changelog files below, so the file
8932 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8933 must refer to the changelog for the current version of
8934 <var>package</var> in question. In practice, this means
8935 that the sources of the target and the destination of the
8936 symlink must be the same (same source package and
8943 Former Debian releases placed all additional documentation
8944 in <file>/usr/doc/<var>package</var></file>. This has been
8945 changed to <file>/usr/share/doc/<var>package</var></file>,
8946 and packages must not put documentation in the directory
8947 <file>/usr/doc/<var>package</var></file>. <footnote>
8948 At this phase of the transition, we no longer require a
8949 symbolic link in <file>/usr/doc/</file>. At a later point,
8950 policy shall change to make the symbolic links a bug.
8956 <heading>Preferred documentation formats</heading>
8959 The unification of Debian documentation is being carried out
8963 If your package comes with extensive documentation in a
8964 markup format that can be converted to various other formats
8965 you should if possible ship HTML versions in a binary
8966 package, in the directory
8967 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8968 its subdirectories.<footnote>
8969 The rationale: The important thing here is that HTML
8970 docs should be available in <em>some</em> package, not
8971 necessarily in the main binary package.
8976 Other formats such as PostScript may be provided at the
8977 package maintainer's discretion.
8981 <sect id="copyrightfile">
8982 <heading>Copyright information</heading>
8985 Every package must be accompanied by a verbatim copy of its
8986 copyright and distribution license in the file
8987 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8988 file must neither be compressed nor be a symbolic link.
8992 In addition, the copyright file must say where the upstream
8993 sources (if any) were obtained. It should name the original
8994 authors of the package and the Debian maintainer(s) who were
8995 involved with its creation.
8999 Packages in the <em>contrib</em> or <em>non-free</em> archive
9000 areas should state in the copyright file that the package is not
9001 part of the Debian GNU/Linux distribution and briefly explain
9006 A copy of the file which will be installed in
9007 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9008 be in <file>debian/copyright</file> in the source package.
9012 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9013 link to another directory in <file>/usr/share/doc</file> only if
9014 the two packages both come from the same source and the
9015 first package Depends on the second. These rules are
9016 important because copyrights must be extractable by
9021 Packages distributed under the UCB BSD license, the Apache
9022 license (version 2.0), the Artistic license, the GNU GPL
9023 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9024 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9025 files under <file>/usr/share/common-licenses</file>,<footnote>
9028 <file>/usr/share/common-licenses/BSD</file>,
9029 <file>/usr/share/common-licenses/Apache-2.0</file>,
9030 <file>/usr/share/common-licenses/Artistic</file>,
9031 <file>/usr/share/common-licenses/GPL-2</file>,
9032 <file>/usr/share/common-licenses/GPL-3</file>,
9033 <file>/usr/share/common-licenses/LGPL-2</file>,
9034 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9035 <file>/usr/share/common-licenses/LGPL-3</file>,
9036 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9037 <file>/usr/share/common-licenses/GFDL-1.3</file>
9040 </footnote> rather than quoting them in the copyright
9045 You should not use the copyright file as a general <file>README</file>
9046 file. If your package has such a file it should be
9047 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9048 <file>README.Debian</file> or some other appropriate place.</p>
9052 <heading>Examples</heading>
9055 Any examples (configurations, source files, whatever),
9056 should be installed in a directory
9057 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9058 files should not be referenced by any program: they're there
9059 for the benefit of the system administrator and users as
9060 documentation only. Architecture-specific example files
9061 should be installed in a directory
9062 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9064 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9065 latter directory itself may be a symbolic link to the
9070 If the purpose of a package is to provide examples, then the
9071 example files may be installed into
9072 <file>/usr/share/doc/<var>package</var></file>.
9076 <sect id="changelogs">
9077 <heading>Changelog files</heading>
9080 Packages that are not Debian-native must contain a
9081 compressed copy of the <file>debian/changelog</file> file from
9082 the Debian source tree in
9083 <file>/usr/share/doc/<var>package</var></file> with the name
9084 <file>changelog.Debian.gz</file>.
9088 If an upstream changelog is available, it should be accessible as
9089 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9090 plain text. If the upstream changelog is distributed in
9091 HTML, it should be made available in that form as
9092 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9093 and a plain text <file>changelog.gz</file> should be generated
9094 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9095 the upstream changelog files do not already conform to this
9096 naming convention, then this may be achieved either by
9097 renaming the files, or by adding a symbolic link, at the
9098 maintainer's discretion.<footnote>
9099 Rationale: People should not have to look in places for
9100 upstream changelogs merely because they are given
9101 different names or are distributed in HTML format.
9106 All of these files should be installed compressed using
9107 <tt>gzip -9</tt>, as they will become large with time even
9108 if they start out small.
9112 If the package has only one changelog which is used both as
9113 the Debian changelog and the upstream one because there is
9114 no separate upstream maintainer then that changelog should
9115 usually be installed as
9116 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9117 there is a separate upstream maintainer, but no upstream
9118 changelog, then the Debian changelog should still be called
9119 <file>changelog.Debian.gz</file>.
9123 For details about the format and contents of the Debian
9124 changelog file, please see <ref id="dpkgchangelog">.
9129 <appendix id="pkg-scope">
9130 <heading>Introduction and scope of these appendices</heading>
9133 These appendices are taken essentially verbatim from the
9134 now-deprecated Packaging Manual, version 3.2.1.0. They are
9135 the chapters which are likely to be of use to package
9136 maintainers and which have not already been included in the
9137 policy document itself. Most of these sections are very likely
9138 not relevant to policy; they should be treated as
9139 documentation for the packaging system. Please note that these
9140 appendices are included for convenience, and for historical
9141 reasons: they used to be part of policy package, and they have
9142 not yet been incorporated into dpkg documentation. However,
9143 they still have value, and hence they are presented here.
9147 They have not yet been checked to ensure that they are
9148 compatible with the contents of policy, and if there are any
9149 contradictions, the version in the main policy document takes
9150 precedence. The remaining chapters of the old Packaging
9151 Manual have also not been read in detail to ensure that there
9152 are not parts which have been left out. Both of these will be
9157 Certain parts of the Packaging manual were integrated into the
9158 Policy Manual proper, and removed from the appendices. Links
9159 have been placed from the old locations to the new ones.
9163 <prgn>dpkg</prgn> is a suite of programs for creating binary
9164 package files and installing and removing them on Unix
9166 <prgn>dpkg</prgn> is targeted primarily at Debian
9167 GNU/Linux, but may work on or be ported to other
9173 The binary packages are designed for the management of
9174 installed executable programs (usually compiled binaries) and
9175 their associated data, though source code examples and
9176 documentation are provided as part of some packages.</p>
9179 This manual describes the technical aspects of creating Debian
9180 binary packages (<file>.deb</file> files). It documents the
9181 behavior of the package management programs
9182 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9183 they interact with packages.</p>
9186 It also documents the interaction between
9187 <prgn>dselect</prgn>'s core and the access method scripts it
9188 uses to actually install the selected packages, and describes
9189 how to create a new access method.</p>
9192 This manual does not go into detail about the options and
9193 usage of the package building and installation tools. It
9194 should therefore be read in conjunction with those programs'
9199 The utility programs which are provided with <prgn>dpkg</prgn>
9200 for managing various system configuration and similar issues,
9201 such as <prgn>update-rc.d</prgn> and
9202 <prgn>install-info</prgn>, are not described in detail here -
9203 please see their man pages.
9207 It is assumed that the reader is reasonably familiar with the
9208 <prgn>dpkg</prgn> System Administrators' manual.
9209 Unfortunately this manual does not yet exist.
9213 The Debian version of the FSF's GNU hello program is provided
9214 as an example for people wishing to create Debian
9215 packages. The Debian <prgn>debmake</prgn> package is
9216 recommended as a very helpful tool in creating and maintaining
9217 Debian packages. However, while the tools and examples are
9218 helpful, they do not replace the need to read and follow the
9219 Policy and Programmer's Manual.</p>
9222 <appendix id="pkg-binarypkg">
9223 <heading>Binary packages (from old Packaging Manual)</heading>
9226 The binary package has two main sections. The first part
9227 consists of various control information files and scripts used
9228 by <prgn>dpkg</prgn> when installing and removing. See <ref
9229 id="pkg-controlarea">.
9233 The second part is an archive containing the files and
9234 directories to be installed.
9238 In the future binary packages may also contain other
9239 components, such as checksums and digital signatures. The
9240 format for the archive is described in full in the
9241 <file>deb(5)</file> man page.
9245 <sect id="pkg-bincreating"><heading>Creating package files -
9246 <prgn>dpkg-deb</prgn>
9250 All manipulation of binary package files is done by
9251 <prgn>dpkg-deb</prgn>; it's the only program that has
9252 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9253 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9254 will spot that the options requested are appropriate to
9255 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9260 In order to create a binary package you must make a
9261 directory tree which contains all the files and directories
9262 you want to have in the file system data part of the package.
9263 In Debian-format source packages this directory is usually
9264 <file>debian/tmp</file>, relative to the top of the package's
9269 They should have the locations (relative to the root of the
9270 directory tree you're constructing) ownerships and
9271 permissions which you want them to have on the system when
9276 With current versions of <prgn>dpkg</prgn> the uid/username
9277 and gid/groupname mappings for the users and groups being
9278 used should be the same on the system where the package is
9279 built and the one where it is installed.
9283 You need to add one special directory to the root of the
9284 miniature file system tree you're creating:
9285 <prgn>DEBIAN</prgn>. It should contain the control
9286 information files, notably the binary package control file
9287 (see <ref id="pkg-controlfile">).
9291 The <prgn>DEBIAN</prgn> directory will not appear in the
9292 file system archive of the package, and so won't be installed
9293 by <prgn>dpkg</prgn> when the package is installed.
9297 When you've prepared the package, you should invoke:
9299 dpkg --build <var>directory</var>
9304 This will build the package in
9305 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9306 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9307 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9312 See the man page <manref name="dpkg-deb" section="8"> for details of how
9313 to examine the contents of this newly-created file. You may find the
9314 output of following commands enlightening:
9316 dpkg-deb --info <var>filename</var>.deb
9317 dpkg-deb --contents <var>filename</var>.deb
9318 dpkg --contents <var>filename</var>.deb
9320 To view the copyright file for a package you could use this command:
9322 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9327 <sect id="pkg-controlarea">
9328 <heading>Package control information files</heading>
9331 The control information portion of a binary package is a
9332 collection of files with names known to <prgn>dpkg</prgn>.
9333 It will treat the contents of these files specially - some
9334 of them contain information used by <prgn>dpkg</prgn> when
9335 installing or removing the package; others are scripts which
9336 the package maintainer wants <prgn>dpkg</prgn> to run.
9340 It is possible to put other files in the package control
9341 area, but this is not generally a good idea (though they
9342 will largely be ignored).
9346 Here is a brief list of the control info files supported by
9347 <prgn>dpkg</prgn> and a summary of what they're used for.
9352 <tag><tt>control</tt>
9355 This is the key description file used by
9356 <prgn>dpkg</prgn>. It specifies the package's name
9357 and version, gives its description for the user,
9358 states its relationships with other packages, and so
9359 forth. See <ref id="sourcecontrolfiles"> and
9360 <ref id="binarycontrolfiles">.
9364 It is usually generated automatically from information
9365 in the source package by the
9366 <prgn>dpkg-gencontrol</prgn> program, and with
9367 assistance from <prgn>dpkg-shlibdeps</prgn>.
9368 See <ref id="pkg-sourcetools">.
9372 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9377 These are executable files (usually scripts) which
9378 <prgn>dpkg</prgn> runs during installation, upgrade
9379 and removal of packages. They allow the package to
9380 deal with matters which are particular to that package
9381 or require more complicated processing than that
9382 provided by <prgn>dpkg</prgn>. Details of when and
9383 how they are called are in <ref id="maintainerscripts">.
9387 It is very important to make these scripts idempotent.
9388 See <ref id="idempotency">.
9392 The maintainer scripts are guaranteed to run with a
9393 controlling terminal and can interact with the user.
9394 See <ref id="controllingterminal">.
9398 <tag><tt>conffiles</tt>
9401 This file contains a list of configuration files which
9402 are to be handled automatically by <prgn>dpkg</prgn>
9403 (see <ref id="pkg-conffiles">). Note that not necessarily
9404 every configuration file should be listed here.
9407 <tag><tt>shlibs</tt>
9410 This file contains a list of the shared libraries
9411 supplied by the package, with dependency details for
9412 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9413 when it determines what dependencies are required in a
9414 package control file. The <tt>shlibs</tt> file format
9415 is described on <ref id="shlibs">.
9420 <sect id="pkg-controlfile">
9421 <heading>The main control information file: <tt>control</tt></heading>
9424 The most important control information file used by
9425 <prgn>dpkg</prgn> when it installs a package is
9426 <tt>control</tt>. It contains all the package's "vital
9431 The binary package control files of packages built from
9432 Debian sources are made by a special tool,
9433 <prgn>dpkg-gencontrol</prgn>, which reads
9434 <file>debian/control</file> and <file>debian/changelog</file> to
9435 find the information it needs. See <ref id="pkg-sourcepkg"> for
9440 The fields in binary package control files are listed in
9441 <ref id="binarycontrolfiles">.
9445 A description of the syntax of control files and the purpose
9446 of the fields is available in <ref id="controlfields">.
9451 <heading>Time Stamps</heading>
9454 See <ref id="timestamps">.
9459 <appendix id="pkg-sourcepkg">
9460 <heading>Source packages (from old Packaging Manual) </heading>
9463 The Debian binary packages in the distribution are generated
9464 from Debian sources, which are in a special format to assist
9465 the easy and automatic building of binaries.
9468 <sect id="pkg-sourcetools">
9469 <heading>Tools for processing source packages</heading>
9472 Various tools are provided for manipulating source packages;
9473 they pack and unpack sources and help build of binary
9474 packages and help manage the distribution of new versions.
9478 They are introduced and typical uses described here; see
9479 <manref name="dpkg-source" section="1"> for full
9480 documentation about their arguments and operation.
9484 For examples of how to construct a Debian source package,
9485 and how to use those utilities that are used by Debian
9486 source packages, please see the <prgn>hello</prgn> example
9490 <sect1 id="pkg-dpkg-source">
9492 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9497 This program is frequently used by hand, and is also
9498 called from package-independent automated building scripts
9499 such as <prgn>dpkg-buildpackage</prgn>.
9503 To unpack a package it is typically invoked with
9505 dpkg-source -x <var>.../path/to/filename</var>.dsc
9510 with the <file><var>filename</var>.tar.gz</file> and
9511 <file><var>filename</var>.diff.gz</file> (if applicable) in
9512 the same directory. It unpacks into
9513 <file><var>package</var>-<var>version</var></file>, and if
9515 <file><var>package</var>-<var>version</var>.orig</file>, in
9516 the current directory.
9520 To create a packed source archive it is typically invoked:
9522 dpkg-source -b <var>package</var>-<var>version</var>
9527 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9528 <file>.diff.gz</file> (if appropriate) in the current
9529 directory. <prgn>dpkg-source</prgn> does not clean the
9530 source tree first - this must be done separately if it is
9535 See also <ref id="pkg-sourcearchives">.</p>
9539 <sect1 id="pkg-dpkg-buildpackage">
9541 <prgn>dpkg-buildpackage</prgn> - overall package-building
9546 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9547 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9548 targets <tt>clean</tt>, <tt>build</tt> and
9549 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9550 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9551 source and binary package upload.
9555 It is usually invoked by hand from the top level of the
9556 built or unbuilt source directory. It may be invoked with
9557 no arguments; useful arguments include:
9558 <taglist compact="compact">
9559 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9562 Do not sign the <tt>.changes</tt> file or the
9563 source package <tt>.dsc</tt> file, respectively.</p>
9565 <tag><tt>-p<var>sign-command</var></tt></tag>
9568 Invoke <var>sign-command</var> instead of finding
9569 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9570 <var>sign-command</var> must behave just like
9571 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9573 <tag><tt>-r<var>root-command</var></tt></tag>
9576 When root privilege is required, invoke the command
9577 <var>root-command</var>. <var>root-command</var>
9578 should invoke its first argument as a command, from
9579 the <prgn>PATH</prgn> if necessary, and pass its
9580 second and subsequent arguments to the command it
9581 calls. If no <var>root-command</var> is supplied
9582 then <var>dpkg-buildpackage</var> will take no
9583 special action to gain root privilege, so that for
9584 most packages it will have to be invoked as root to
9587 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9590 Two types of binary-only build and upload - see
9591 <manref name="dpkg-source" section="1">.
9598 <sect1 id="pkg-dpkg-gencontrol">
9600 <prgn>dpkg-gencontrol</prgn> - generates binary package
9605 This program is usually called from <file>debian/rules</file>
9606 (see <ref id="pkg-sourcetree">) in the top level of the source
9611 This is usually done just before the files and directories in the
9612 temporary directory tree where the package is being built have their
9613 permissions and ownerships set and the package is constructed using
9614 <prgn>dpkg-deb/</prgn>
9616 This is so that the control file which is produced has
9617 the right permissions
9622 <prgn>dpkg-gencontrol</prgn> must be called after all the
9623 files which are to go into the package have been placed in
9624 the temporary build directory, so that its calculation of
9625 the installed size of a package is correct.
9629 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9630 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9631 variable substitutions created by
9632 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9637 For a package which generates only one binary package, and
9638 which builds it in <file>debian/tmp</file> relative to the top
9639 of the source package, it is usually sufficient to call
9640 <prgn>dpkg-gencontrol</prgn>.
9644 Sources which build several binaries will typically need
9647 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9648 </example> The <tt>-P</tt> tells
9649 <prgn>dpkg-gencontrol</prgn> that the package is being
9650 built in a non-default directory, and the <tt>-p</tt>
9651 tells it which package's control file should be generated.
9655 <prgn>dpkg-gencontrol</prgn> also adds information to the
9656 list of files in <file>debian/files</file>, for the benefit of
9657 (for example) a future invocation of
9658 <prgn>dpkg-genchanges</prgn>.</p>
9661 <sect1 id="pkg-dpkg-shlibdeps">
9663 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9668 This program is usually called from <file>debian/rules</file>
9669 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9670 id="pkg-sourcetree">), in the top level of the source tree.
9674 Its arguments are executables and shared libraries
9677 They may be specified either in the locations in the
9678 source tree where they are created or in the locations
9679 in the temporary build tree where they are installed
9680 prior to binary package creation.
9682 </footnote> for which shared library dependencies should
9683 be included in the binary package's control file.
9687 If some of the found shared libraries should only
9688 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9689 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9690 by using the <tt>-d<var>dependency-field</var></tt> option
9691 before those executable(s). (Each <tt>-d</tt> option
9692 takes effect until the next <tt>-d</tt>.)
9696 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9697 output control file to be modified. Instead by default it
9698 adds to the <file>debian/substvars</file> file variable
9699 settings like <tt>shlibs:Depends</tt>. These variable
9700 settings must be referenced in dependency fields in the
9701 appropriate per-binary-package sections of the source
9706 For example, a package that generates an essential part
9707 which requires dependencies, and optional parts that
9708 which only require a recommendation, would separate those
9709 two sets of dependencies into two different fields.<footnote>
9710 At the time of writing, an example for this was the
9711 <package/xmms/ package, with Depends used for the xmms
9712 executable, Recommends for the plug-ins and Suggests for
9713 even more optional features provided by unzip.
9715 It can say in its <file>debian/rules</file>:
9717 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9718 -dRecommends <var>optionalpart anotheroptionalpart</var>
9720 and then in its main control file <file>debian/control</file>:
9723 Depends: ${shlibs:Depends}
9724 Recommends: ${shlibs:Recommends}
9730 Sources which produce several binary packages with
9731 different shared library dependency requirements can use
9732 the <tt>-p<var>varnameprefix</var></tt> option to override
9733 the default <tt>shlibs:</tt> prefix (one invocation of
9734 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9735 They can thus produce several sets of dependency
9736 variables, each of the form
9737 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9738 which can be referred to in the appropriate parts of the
9739 binary package control files.
9744 <sect1 id="pkg-dpkg-distaddfile">
9746 <prgn>dpkg-distaddfile</prgn> - adds a file to
9747 <file>debian/files</file>
9751 Some packages' uploads need to include files other than
9752 the source and binary package files.
9756 <prgn>dpkg-distaddfile</prgn> adds a file to the
9757 <file>debian/files</file> file so that it will be included in
9758 the <file>.changes</file> file when
9759 <prgn>dpkg-genchanges</prgn> is run.
9763 It is usually invoked from the <tt>binary</tt> target of
9764 <file>debian/rules</file>:
9766 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9768 The <var>filename</var> is relative to the directory where
9769 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9770 is usually the directory above the top level of the source
9771 tree. The <file>debian/rules</file> target should put the
9772 file there just before or just after calling
9773 <prgn>dpkg-distaddfile</prgn>.
9777 The <var>section</var> and <var>priority</var> are passed
9778 unchanged into the resulting <file>.changes</file> file.
9783 <sect1 id="pkg-dpkg-genchanges">
9785 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9790 This program is usually called by package-independent
9791 automatic building scripts such as
9792 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9797 It is usually called in the top level of a built source
9798 tree, and when invoked with no arguments will print out a
9799 straightforward <file>.changes</file> file based on the
9800 information in the source package's changelog and control
9801 file and the binary and source packages which should have
9807 <sect1 id="pkg-dpkg-parsechangelog">
9809 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9810 representation of a changelog
9814 This program is used internally by
9815 <prgn>dpkg-source</prgn> et al. It may also occasionally
9816 be useful in <file>debian/rules</file> and elsewhere. It
9817 parses a changelog, <file>debian/changelog</file> by default,
9818 and prints a control-file format representation of the
9819 information in it to standard output.
9823 <sect1 id="pkg-dpkg-architecture">
9825 <prgn>dpkg-architecture</prgn> - information about the build and
9830 This program can be used manually, but is also invoked by
9831 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9832 environment or make variables which specify the build and host
9833 architecture for the package building process.
9838 <sect id="pkg-sourcetree">
9839 <heading>The Debianised source tree</heading>
9842 The source archive scheme described later is intended to
9843 allow a Debianised source tree with some associated control
9844 information to be reproduced and transported easily. The
9845 Debianised source tree is a version of the original program
9846 with certain files added for the benefit of the
9847 Debianisation process, and with any other changes required
9848 made to the rest of the source code and installation
9853 The extra files created for Debian are in the subdirectory
9854 <file>debian</file> of the top level of the Debianised source
9855 tree. They are described below.
9858 <sect1 id="pkg-debianrules">
9859 <heading><file>debian/rules</file> - the main building script</heading>
9862 See <ref id="debianrules">.
9867 <sect1 id="pkg-dpkgchangelog">
9868 <heading><file>debian/changelog</file></heading>
9871 See <ref id="dpkgchangelog">.
9874 <sect2><heading>Defining alternative changelog formats
9878 It is possible to use a different format to the standard
9879 one, by providing a parser for the format you wish to
9884 In order to have <tt>dpkg-parsechangelog</tt> run your
9885 parser, you must include a line within the last 40 lines
9886 of your file matching the Perl regular expression:
9887 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9888 parentheses should be the name of the format. For
9889 example, you might say:
9891 @@@ changelog-format: joebloggs @@@
9893 Changelog format names are non-empty strings of alphanumerics.
9897 If such a line exists then <tt>dpkg-parsechangelog</tt>
9898 will look for the parser as
9899 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9901 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9902 it is an error for it not to find it, or for it not to
9903 be an executable program. The default changelog format
9904 is <tt>dpkg</tt>, and a parser for it is provided with
9905 the <tt>dpkg</tt> package.
9909 The parser will be invoked with the changelog open on
9910 standard input at the start of the file. It should read
9911 the file (it may seek if it wishes) to determine the
9912 information required and return the parsed information
9913 to standard output in the form of a series of control
9914 fields in the standard format. By default it should
9915 return information about only the most recent version in
9916 the changelog; it should accept a
9917 <tt>-v<var>version</var></tt> option to return changes
9918 information from all versions present <em>strictly
9919 after</em> <var>version</var>, and it should then be an
9920 error for <var>version</var> not to be present in the
9926 <list compact="compact">
9927 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9928 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9929 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9930 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9931 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9932 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9933 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9938 If several versions are being returned (due to the use
9939 of <tt>-v</tt>), the urgency value should be of the
9940 highest urgency code listed at the start of any of the
9941 versions requested followed by the concatenated
9942 (space-separated) comments from all the versions
9943 requested; the maintainer, version, distribution and
9944 date should always be from the most recent version.
9948 For the format of the <tt>Changes</tt> field see
9949 <ref id="f-Changes">.
9953 If the changelog format which is being parsed always or
9954 almost always leaves a blank line between individual
9955 change notes these blank lines should be stripped out,
9956 so as to make the resulting output compact.
9960 If the changelog format does not contain date or package
9961 name information this information should be omitted from
9962 the output. The parser should not attempt to synthesize
9963 it or find it from other sources.
9967 If the changelog does not have the expected format the
9968 parser should exit with a nonzero exit status, rather
9969 than trying to muddle through and possibly generating
9974 A changelog parser may not interact with the user at
9980 <sect1 id="pkg-srcsubstvars">
9981 <heading><file>debian/substvars</file> and variable substitutions</heading>
9984 See <ref id="substvars">.
9990 <heading><file>debian/files</file></heading>
9993 See <ref id="debianfiles">.
9997 <sect1><heading><file>debian/tmp</file>
10001 This is the canonical temporary location for the
10002 construction of binary packages by the <tt>binary</tt>
10003 target. The directory <file>tmp</file> serves as the root of
10004 the file system tree as it is being constructed (for
10005 example, by using the package's upstream makefiles install
10006 targets and redirecting the output there), and it also
10007 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10008 id="pkg-bincreating">.
10012 If several binary packages are generated from the same
10013 source tree it is usual to use several
10014 <file>debian/tmp<var>something</var></file> directories, for
10015 example <file>tmp-a</file> or <file>tmp-doc</file>.
10019 Whatever <file>tmp</file> directories are created and used by
10020 <tt>binary</tt> must of course be removed by the
10021 <tt>clean</tt> target.</p></sect1>
10025 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10029 As it exists on the FTP site, a Debian source package
10030 consists of three related files. You must have the right
10031 versions of all three to be able to use them.
10036 <tag>Debian source control file - <tt>.dsc</tt></tag>
10038 This file is a control file used by <prgn>dpkg-source</prgn>
10039 to extract a source package.
10040 See <ref id="debiansourcecontrolfiles">.
10044 Original source archive -
10046 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10052 This is a compressed (with <tt>gzip -9</tt>)
10053 <prgn>tar</prgn> file containing the source code from
10054 the upstream authors of the program.
10059 Debianisation diff -
10061 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10067 This is a unified context diff (<tt>diff -u</tt>)
10068 giving the changes which are required to turn the
10069 original source into the Debian source. These changes
10070 may only include editing and creating plain files.
10071 The permissions of files, the targets of symbolic
10072 links and the characteristics of special files or
10073 pipes may not be changed and no files may be removed
10078 All the directories in the diff must exist, except the
10079 <file>debian</file> subdirectory of the top of the source
10080 tree, which will be created by
10081 <prgn>dpkg-source</prgn> if necessary when unpacking.
10085 The <prgn>dpkg-source</prgn> program will
10086 automatically make the <file>debian/rules</file> file
10087 executable (see below).</p></item>
10092 If there is no original source code - for example, if the
10093 package is specially prepared for Debian or the Debian
10094 maintainer is the same as the upstream maintainer - the
10095 format is slightly different: then there is no diff, and the
10097 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10098 and preferably contains a directory named
10099 <file><var>package</var>-<var>version</var></file>.
10104 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10107 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10108 Debian source package. However, if it is not available it
10109 is possible to unpack a Debian source archive as follows:
10110 <enumlist compact="compact">
10113 Untar the tarfile, which will create a <file>.orig</file>
10117 <p>Rename the <file>.orig</file> directory to
10118 <file><var>package</var>-<var>version</var></file>.</p>
10122 Create the subdirectory <file>debian</file> at the top of
10123 the source tree.</p>
10125 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10127 <item><p>Untar the tarfile again if you want a copy of the original
10128 source code alongside the Debianised version.</p>
10133 It is not possible to generate a valid Debian source archive
10134 without using <prgn>dpkg-source</prgn>. In particular,
10135 attempting to use <prgn>diff</prgn> directly to generate the
10136 <file>.diff.gz</file> file will not work.
10140 <heading>Restrictions on objects in source packages</heading>
10143 The source package may not contain any hard links
10145 This is not currently detected when building source
10146 packages, but only when extracting
10150 Hard links may be permitted at some point in the
10151 future, but would require a fair amount of
10153 </footnote>, device special files, sockets or setuid or
10156 Setgid directories are allowed.
10161 The source packaging tools manage the changes between the
10162 original and Debianised source using <prgn>diff</prgn> and
10163 <prgn>patch</prgn>. Turning the original source tree as
10164 included in the <file>.orig.tar.gz</file> into the debianised
10165 source must not involve any changes which cannot be
10166 handled by these tools. Problematic changes which cause
10167 <prgn>dpkg-source</prgn> to halt with an error when
10168 building the source package are:
10169 <list compact="compact">
10170 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10172 <item><p>Changing the targets of symbolic links.</p>
10174 <item><p>Creating directories, other than <file>debian</file>.</p>
10176 <item><p>Changes to the contents of binary files.</p></item>
10177 </list> Changes which cause <prgn>dpkg-source</prgn> to
10178 print a warning but continue anyway are:
10179 <list compact="compact">
10182 Removing files, directories or symlinks.
10184 Renaming a file is not treated specially - it is
10185 seen as the removal of the old file (which
10186 generates a warning, but is otherwise ignored),
10187 and the creation of the new one.
10193 Changed text files which are missing the usual final
10194 newline (either in the original or the modified
10199 Changes which are not represented, but which are not detected by
10200 <prgn>dpkg-source</prgn>, are:
10201 <list compact="compact">
10202 <item><p>Changing the permissions of files (other than
10203 <file>debian/rules</file>) and directories.</p></item>
10208 The <file>debian</file> directory and <file>debian/rules</file>
10209 are handled specially by <prgn>dpkg-source</prgn> - before
10210 applying the changes it will create the <file>debian</file>
10211 directory, and afterwards it will make
10212 <file>debian/rules</file> world-executable.
10218 <appendix id="pkg-controlfields">
10219 <heading>Control files and their fields (from old Packaging Manual)</heading>
10222 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10223 data in a common format, known as control files. Binary and
10224 source packages have control data as do the <file>.changes</file>
10225 files which control the installation of uploaded files, and
10226 <prgn>dpkg</prgn>'s internal databases are in a similar
10231 <heading>Syntax of control files</heading>
10234 See <ref id="controlsyntax">.
10238 It is important to note that there are several fields which
10239 are optional as far as <prgn>dpkg</prgn> and the related
10240 tools are concerned, but which must appear in every Debian
10241 package, or whose omission may cause problems.
10246 <heading>List of fields</heading>
10249 See <ref id="controlfieldslist">.
10253 This section now contains only the fields that didn't belong
10254 to the Policy manual.
10257 <sect1 id="pkg-f-Filename">
10258 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10261 These fields in <tt>Packages</tt> files give the
10262 filename(s) of (the parts of) a package in the
10263 distribution directories, relative to the root of the
10264 Debian hierarchy. If the package has been split into
10265 several parts the parts are all listed in order, separated
10270 <sect1 id="pkg-f-Size">
10271 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10274 These fields in <file>Packages</file> files give the size (in
10275 bytes, expressed in decimal) and MD5 checksum of the
10276 file(s) which make(s) up a binary package in the
10277 distribution. If the package is split into several parts
10278 the values for the parts are listed in order, separated by
10283 <sect1 id="pkg-f-Status">
10284 <heading><tt>Status</tt></heading>
10287 This field in <prgn>dpkg</prgn>'s status file records
10288 whether the user wants a package installed, removed or
10289 left alone, whether it is broken (requiring
10290 re-installation) or not and what its current state on the
10291 system is. Each of these pieces of information is a
10296 <sect1 id="pkg-f-Config-Version">
10297 <heading><tt>Config-Version</tt></heading>
10300 If a package is not installed or not configured, this
10301 field in <prgn>dpkg</prgn>'s status file records the last
10302 version of the package which was successfully
10307 <sect1 id="pkg-f-Conffiles">
10308 <heading><tt>Conffiles</tt></heading>
10311 This field in <prgn>dpkg</prgn>'s status file contains
10312 information about the automatically-managed configuration
10313 files held by a package. This field should <em>not</em>
10314 appear anywhere in a package!
10319 <heading>Obsolete fields</heading>
10322 These are still recognized by <prgn>dpkg</prgn> but should
10323 not appear anywhere any more.
10325 <taglist compact="compact">
10327 <tag><tt>Revision</tt></tag>
10328 <tag><tt>Package-Revision</tt></tag>
10329 <tag><tt>Package_Revision</tt></tag>
10331 The Debian revision part of the package version was
10332 at one point in a separate control file field. This
10333 field went through several names.
10336 <tag><tt>Recommended</tt></tag>
10337 <item>Old name for <tt>Recommends</tt>.</item>
10339 <tag><tt>Optional</tt></tag>
10340 <item>Old name for <tt>Suggests</tt>.</item>
10342 <tag><tt>Class</tt></tag>
10343 <item>Old name for <tt>Priority</tt>.</item>
10352 <appendix id="pkg-conffiles">
10353 <heading>Configuration file handling (from old Packaging Manual)</heading>
10356 <prgn>dpkg</prgn> can do a certain amount of automatic
10357 handling of package configuration files.
10361 Whether this mechanism is appropriate depends on a number of
10362 factors, but basically there are two approaches to any
10363 particular configuration file.
10367 The easy method is to ship a best-effort configuration in the
10368 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10369 handle updates. If the user is unlikely to want to edit the
10370 file, but you need them to be able to without losing their
10371 changes, and a new package with a changed version of the file
10372 is only released infrequently, this is a good approach.
10376 The hard method is to build the configuration file from
10377 scratch in the <prgn>postinst</prgn> script, and to take the
10378 responsibility for fixing any mistakes made in earlier
10379 versions of the package automatically. This will be
10380 appropriate if the file is likely to need to be different on
10384 <sect><heading>Automatic handling of configuration files by
10389 A package may contain a control area file called
10390 <tt>conffiles</tt>. This file should be a list of filenames
10391 of configuration files needing automatic handling, separated
10392 by newlines. The filenames should be absolute pathnames,
10393 and the files referred to should actually exist in the
10398 When a package is upgraded <prgn>dpkg</prgn> will process
10399 the configuration files during the configuration stage,
10400 shortly before it runs the package's <prgn>postinst</prgn>
10405 For each file it checks to see whether the version of the
10406 file included in the package is the same as the one that was
10407 included in the last version of the package (the one that is
10408 being upgraded from); it also compares the version currently
10409 installed on the system with the one shipped with the last
10414 If neither the user nor the package maintainer has changed
10415 the file, it is left alone. If one or the other has changed
10416 their version, then the changed version is preferred - i.e.,
10417 if the user edits their file, but the package maintainer
10418 doesn't ship a different version, the user's changes will
10419 stay, silently, but if the maintainer ships a new version
10420 and the user hasn't edited it the new version will be
10421 installed (with an informative message). If both have
10422 changed their version the user is prompted about the problem
10423 and must resolve the differences themselves.
10427 The comparisons are done by calculating the MD5 message
10428 digests of the files, and storing the MD5 of the file as it
10429 was included in the most recent version of the package.
10433 When a package is installed for the first time
10434 <prgn>dpkg</prgn> will install the file that comes with it,
10435 unless that would mean overwriting a file already on the
10440 However, note that <prgn>dpkg</prgn> will <em>not</em>
10441 replace a conffile that was removed by the user (or by a
10442 script). This is necessary because with some programs a
10443 missing file produces an effect hard or impossible to
10444 achieve in another way, so that a missing file needs to be
10445 kept that way if the user did it.
10449 Note that a package should <em>not</em> modify a
10450 <prgn>dpkg</prgn>-handled conffile in its maintainer
10451 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10452 the user confusing and possibly dangerous options for
10453 conffile update when the package is upgraded.</p>
10456 <sect><heading>Fully-featured maintainer script configuration
10461 For files which contain site-specific information such as
10462 the hostname and networking details and so forth, it is
10463 better to create the file in the package's
10464 <prgn>postinst</prgn> script.
10468 This will typically involve examining the state of the rest
10469 of the system to determine values and other information, and
10470 may involve prompting the user for some information which
10471 can't be obtained some other way.
10475 When using this method there are a couple of important
10476 issues which should be considered:
10480 If you discover a bug in the program which generates the
10481 configuration file, or if the format of the file changes
10482 from one version to the next, you will have to arrange for
10483 the postinst script to do something sensible - usually this
10484 will mean editing the installed configuration file to remove
10485 the problem or change the syntax. You will have to do this
10486 very carefully, since the user may have changed the file,
10487 perhaps to fix the very problem that your script is trying
10488 to deal with - you will have to detect these situations and
10489 deal with them correctly.
10493 If you do go down this route it's probably a good idea to
10494 make the program that generates the configuration file(s) a
10495 separate program in <file>/usr/sbin</file>, by convention called
10496 <file><var>package</var>config</file> and then run that if
10497 appropriate from the post-installation script. The
10498 <tt><var>package</var>config</tt> program should not
10499 unquestioningly overwrite an existing configuration - if its
10500 mode of operation is geared towards setting up a package for
10501 the first time (rather than any arbitrary reconfiguration
10502 later) you should have it check whether the configuration
10503 already exists, and require a <tt>--force</tt> flag to
10504 overwrite it.</p></sect>
10507 <appendix id="pkg-alternatives"><heading>Alternative versions of
10508 an interface - <prgn>update-alternatives</prgn> (from old
10513 When several packages all provide different versions of the
10514 same program or file it is useful to have the system select a
10515 default, but to allow the system administrator to change it
10516 and have their decisions respected.
10520 For example, there are several versions of the <prgn>vi</prgn>
10521 editor, and there is no reason to prevent all of them from
10522 being installed at once, each under their own name
10523 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10524 Nevertheless it is desirable to have the name <tt>vi</tt>
10525 refer to something, at least by default.
10529 If all the packages involved cooperate, this can be done with
10530 <prgn>update-alternatives</prgn>.
10534 Each package provides its own version under its own name, and
10535 calls <prgn>update-alternatives</prgn> in its postinst to
10536 register its version (and again in its prerm to deregister
10541 See the man page <manref name="update-alternatives"
10542 section="8"> for details.
10546 If <prgn>update-alternatives</prgn> does not seem appropriate
10547 you may wish to consider using diversions instead.</p>
10550 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10551 package's version of a file (from old Packaging Manual)
10555 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10556 when it reinstalls the package it belongs to, and to have it
10557 put the file from the package somewhere else instead.
10561 This can be used locally to override a package's version of a
10562 file, or by one package to override another's version (or
10563 provide a wrapper for it).
10567 Before deciding to use a diversion, read <ref
10568 id="pkg-alternatives"> to see if you really want a diversion
10569 rather than several alternative versions of a program.
10573 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10574 and updated by a special program <prgn>dpkg-divert</prgn>.
10575 Please see <manref name="dpkg-divert" section="8"> for full
10576 details of its operation.
10580 When a package wishes to divert a file from another, it should
10581 call <prgn>dpkg-divert</prgn> in its preinst to add the
10582 diversion and rename the existing file. For example,
10583 supposing that a <prgn>smailwrapper</prgn> package wishes to
10584 install a wrapper around <file>/usr/sbin/smail</file>:
10586 dpkg-divert --package smailwrapper --add --rename \
10587 --divert /usr/sbin/smail.real /usr/sbin/smail
10588 </example> The <tt>--package smailwrapper</tt> ensures that
10589 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10590 can bypass the diversion and get installed as the true version.
10591 It's safe to add the diversion unconditionally on upgrades since
10592 it will be left unchanged if it already exists, but
10593 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10594 message, make the command conditional on the version from which
10595 the package is being upgraded:
10597 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10598 dpkg-divert --package smailwrapper --add --rename \
10599 --divert /usr/sbin/smail.real /usr/sbin/smail
10601 </example> where <tt>1.0-2</tt> is the version at which the
10602 diversion was first added to the package. Running the command
10603 during abort-upgrade is pointless but harmless.
10607 The postrm has to do the reverse:
10609 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10610 dpkg-divert --package smailwrapper --remove --rename \
10611 --divert /usr/sbin/smail.real /usr/sbin/smail
10613 </example> If the diversion was added at a particular version, the
10614 postrm should also handle the failure case of upgrading from an
10615 older version (unless the older version is so old that direct
10616 upgrades are no longer supported):
10618 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10619 dpkg-divert --package smailwrapper --remove --rename \
10620 --divert /usr/sbin/smail.real /usr/sbin/smail
10622 </example> where <tt>1.02-2</tt> is the version at which the
10623 diversion was first added to the package. The postrm should not
10624 remove the diversion on upgrades both because there's no reason to
10625 remove the diversion only to immediately re-add it and since the
10626 postrm of the old package is run after unpacking so the removal of
10627 the diversion will fail.
10631 Do not attempt to divert a file which is vitally important for
10632 the system's operation - when using <prgn>dpkg-divert</prgn>
10633 there is a time, after it has been diverted but before
10634 <prgn>dpkg</prgn> has installed the new version, when the file
10635 does not exist.</p>
10640 <!-- Local variables: -->
10641 <!-- indent-tabs-mode: t -->
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