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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 These are the copyright dates of the original Policy manual.
29 Since then, this manual has been updated by many others. No
30 comprehensive collection of copyright notices for subsequent
35 This manual is free software; you may redistribute it and/or
36 modify it under the terms of the GNU General Public License
37 as published by the Free Software Foundation; either version
38 2, or (at your option) any later version.
42 This is distributed in the hope that it will be useful, but
43 <em>without any warranty</em>; without even the implied
44 warranty of merchantability or fitness for a particular
45 purpose. See the GNU General Public License for more
50 A copy of the GNU General Public License is available as
51 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
52 distribution or on the World Wide Web at
53 <url id="http://www.gnu.org/copyleft/gpl.html"
54 name="the GNU General Public Licence">. You can also
55 obtain it by writing to the Free Software Foundation, Inc.,
56 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
64 <heading>About this manual</heading>
66 <heading>Scope</heading>
68 This manual describes the policy requirements for the Debian
69 GNU/Linux distribution. This includes the structure and
70 contents of the Debian archive and several design issues of the
71 operating system, as well as technical requirements that
72 each package must satisfy to be included in the
77 This manual also describes Debian policy as it relates to
78 creating Debian packages. It is not a tutorial on how to build
79 packages, nor is it exhaustive where it comes to describing
80 the behavior of the packaging system. Instead, this manual
81 attempts to define the interface to the package management
82 system that the developers have to be conversant with.<footnote>
83 Informally, the criteria used for inclusion is that the
84 material meet one of the following requirements:
85 <taglist compact="compact">
86 <tag>Standard interfaces</tag>
88 The material presented represents an interface to
89 the packaging system that is mandated for use, and
90 is used by, a significant number of packages, and
91 therefore should not be changed without peer
92 review. Package maintainers can then rely on this
93 interfaces not changing, and the package
94 management software authors need to ensure
95 compatibility with these interface
96 definitions. (Control file and changelog file
97 formats are examples.)
99 <tag>Chosen Convention</tag>
101 If there are a number of technically viable choices
102 that can be made, but one needs to select one of
103 these options for inter-operability. The version
104 number format is one example.
107 Please note that these are not mutually exclusive;
108 selected conventions often become parts of standard
114 The footnotes present in this manual are
115 merely informative, and are not part of Debian policy itself.
119 The appendices to this manual are not necessarily normative,
120 either. Please see <ref id="pkg-scope"> for more information.
124 In the normative part of this manual,
125 the words <em>must</em>, <em>should</em> and
126 <em>may</em>, and the adjectives <em>required</em>,
127 <em>recommended</em> and <em>optional</em>, are used to
128 distinguish the significance of the various guidelines in
129 this policy document. Packages that do not conform to the
130 guidelines denoted by <em>must</em> (or <em>required</em>)
131 will generally not be considered acceptable for the Debian
132 distribution. Non-conformance with guidelines denoted by
133 <em>should</em> (or <em>recommended</em>) will generally be
134 considered a bug, but will not necessarily render a package
135 unsuitable for distribution. Guidelines denoted by
136 <em>may</em> (or <em>optional</em>) are truly optional and
137 adherence is left to the maintainer's discretion.
141 These classifications are roughly equivalent to the bug
142 severities <em>serious</em> (for <em>must</em> or
143 <em>required</em> directive violations), <em>minor</em>,
144 <em>normal</em> or <em>important</em>
145 (for <em>should</em> or <em>recommended</em> directive
146 violations) and <em>wishlist</em> (for <em>optional</em>
149 Compare RFC 2119. Note, however, that these words are
150 used in a different way in this document.
155 Much of the information presented in this manual will be
156 useful even when building a package which is to be
157 distributed in some other way or is intended for local use
163 <heading>New versions of this document</heading>
166 This manual is distributed via the Debian package
167 <package><url name="debian-policy"
168 id="http://packages.debian.org/debian-policy"></package>
169 (<httpsite>packages.debian.org</httpsite>
170 <httppath>/debian-policy</httppath>).
174 The current version of this document is also available from
175 the Debian web mirrors at
176 <tt><url name="/doc/debian-policy/"
177 id="http://www.debian.org/doc/debian-policy/"></tt>.
179 <httpsite>www.debian.org</httpsite>
180 <httppath>/doc/debian-policy/</httppath>)
181 Also available from the same directory are several other
182 formats: <file>policy.html.tar.gz</file>
183 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
184 <file>policy.pdf.gz</file>
185 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
186 and <file>policy.ps.gz</file>
187 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
191 The <package>debian-policy</package> package also includes the file
192 <file>upgrading-checklist.txt.gz</file> which indicates policy
193 changes between versions of this document.
198 <heading>Authors and Maintainers</heading>
201 Originally called "Debian GNU/Linux Policy Manual", this
202 manual was initially written in 1996 by Ian Jackson.
203 It was revised on November 27th, 1996 by David A. Morris.
204 Christian Schwarz added new sections on March 15th, 1997,
205 and reworked/restructured it in April-July 1997.
206 Christoph Lameter contributed the "Web Standard".
207 Julian Gilbey largely restructured it in 2001.
211 Since September 1998, the responsibility for the contents of
212 this document lies on the <url name="debian-policy mailing list"
213 id="mailto:debian-policy@lists.debian.org">. Proposals
214 are discussed there and inserted into policy after a certain
215 consensus is established.
216 <!-- insert shameless policy-process plug here eventually -->
217 The actual editing is done by a group of maintainers that have
218 no editorial powers. These are the current maintainers:
221 <item>Julian Gilbey</item>
222 <item>Branden Robinson</item>
223 <item>Josip Rodin</item>
224 <item>Manoj Srivastava</item>
229 While the authors of this document have tried hard to avoid
230 typos and other errors, these do still occur. If you discover
231 an error in this manual or if you want to give any
232 comments, suggestions, or criticisms please send an email to
233 the Debian Policy List,
234 <email>debian-policy@lists.debian.org</email>, or submit a
235 bug report against the <tt>debian-policy</tt> package.
239 Please do not try to reach the individual authors or maintainers
240 of the Policy Manual regarding changes to the Policy.
245 <heading>Related documents</heading>
248 There are several other documents other than this Policy Manual
249 that are necessary to fully understand some Debian policies and
254 The external "sub-policy" documents are referred to in:
255 <list compact="compact">
256 <item><ref id="fhs"></item>
257 <item><ref id="virtual_pkg"></item>
258 <item><ref id="menus"></item>
259 <item><ref id="mime"></item>
260 <item><ref id="perl"></item>
261 <item><ref id="maintscriptprompt"></item>
262 <item><ref id="emacs"></item>
267 In addition to those, which carry the weight of policy, there
268 is the Debian Developer's Reference. This document describes
269 procedures and resources for Debian developers, but it is
270 <em>not</em> normative; rather, it includes things that don't
271 belong in the Policy, such as best practices for developers.
275 The Developer's Reference is available in the
276 <package>developers-reference</package> package.
277 It's also available from the Debian web mirrors at
278 <tt><url name="/doc/developers-reference/"
279 id="http://www.debian.org/doc/developers-reference/"></tt>.
283 <sect id="definitions">
284 <heading>Definitions</heading>
287 The following terms are used in this Policy Manual:
291 The character encoding specified by ANSI X3.4-1986 and its
292 predecessor standards, referred to in MIME as US-ASCII, and
293 corresponding to an encoding in eight bits per character of
294 the first 128 <url id="http://www.unicode.org/"
295 name="Unicode"> characters, with the eighth bit always zero.
299 The transformation format (sometimes called encoding) of
300 <url id="http://www.unicode.org/" name="Unicode"> defined by
301 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
302 name="RFC 3629">. UTF-8 has the useful property of having
303 ASCII as a subset, so any text encoded in ASCII is trivially
313 <heading>The Debian Archive</heading>
316 The Debian GNU/Linux system is maintained and distributed as a
317 collection of <em>packages</em>. Since there are so many of
318 them (currently well over 15000), they are split into
319 <em>sections</em> and given <em>priorities</em> to simplify
320 the handling of them.
324 The effort of the Debian project is to build a free operating
325 system, but not every package we want to make accessible is
326 <em>free</em> in our sense (see the Debian Free Software
327 Guidelines, below), or may be imported/exported without
328 restrictions. Thus, the archive is split into areas<footnote>
329 The Debian archive software uses the term "component" internally
330 and in the Release file format to refer to the division of an
331 archive. The Debian Social Contract simply refers to "areas."
332 This document uses terminology similar to the Social Contract.
333 </footnote> based on their licenses and other restrictions.
337 The aims of this are:
339 <list compact="compact">
340 <item>to allow us to make as much software available as we can</item>
341 <item>to allow us to encourage everyone to write free software,
343 <item>to allow us to make it easy for people to produce
344 CD-ROMs of our system without violating any licenses,
345 import/export restrictions, or any other laws.</item>
350 The <em>main</em> archive area forms the <em>Debian GNU/Linux
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 Every package in <em>main</em> must comply with the DFSG
469 (Debian Free Software Guidelines).
473 In addition, the packages in <em>main</em>
474 <list compact="compact">
476 must not require a package outside of <em>main</em>
477 for compilation or execution (thus, the package must
478 not declare a "Depends", "Recommends", or
479 "Build-Depends" relationship on a non-<em>main</em>
483 must not be so buggy that we refuse to support them,
487 must meet all policy requirements presented in this
496 <heading>The contrib archive area</heading>
499 Every package in <em>contrib</em> must comply with the DFSG.
503 In addition, the packages in <em>contrib</em>
504 <list compact="compact">
506 must not be so buggy that we refuse to support them,
510 must meet all policy requirements presented in this
518 Examples of packages which would be included in
519 <em>contrib</em> are:
520 <list compact="compact">
522 free packages which require <em>contrib</em>,
523 <em>non-free</em> packages or packages which are not
524 in our archive at all for compilation or execution,
528 wrapper packages or other sorts of free accessories for
535 <sect1 id="non-free">
536 <heading>The non-free archive area</heading>
539 Packages must be placed in <em>non-free</em> if they are
540 not compliant with the DFSG or are encumbered by patents
541 or other legal issues that make their distribution
546 In addition, the packages in <em>non-free</em>
547 <list compact="compact">
549 must not be so buggy that we refuse to support them,
553 must meet all policy requirements presented in this
554 manual that it is possible for them to meet.
556 It is possible that there are policy
557 requirements which the package is unable to
558 meet, for example, if the source is
559 unavailable. These situations will need to be
560 handled on a case-by-case basis.
569 <sect id="pkgcopyright">
570 <heading>Copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of
574 its copyright and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
580 We reserve the right to restrict files from being included
581 anywhere in our archives if
582 <list compact="compact">
584 their use or distribution would break a law,
587 there is an ethical conflict in their distribution or
591 we would have to sign a license for them, or
594 their distribution would conflict with other project
601 Programs whose authors encourage the user to make
602 donations are fine for the main distribution, provided
603 that the authors do not claim that not donating is
604 immoral, unethical, illegal or something similar; in such
605 a case they must go in <em>non-free</em>.
609 Packages whose copyright permission notices (or patent
610 problems) do not even allow redistribution of binaries
611 only, and where no special permission has been obtained,
612 must not be placed on the Debian FTP site and its mirrors
617 Note that under international copyright law (this applies
618 in the United States, too), <em>no</em> distribution or
619 modification of a work is allowed without an explicit
620 notice saying so. Therefore a program without a copyright
621 notice <em>is</em> copyrighted and you may not do anything
622 to it without risking being sued! Likewise if a program
623 has a copyright notice but no statement saying what is
624 permitted then nothing is permitted.
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <sect id="subsections">
649 <heading>Sections</heading>
652 The packages in the archive areas <em>main</em>,
653 <em>contrib</em> and <em>non-free</em> are grouped further into
654 <em>sections</em> to simplify handling.
658 The archive area and section for each package should be
659 specified in the package's <tt>Section</tt> control record (see
660 <ref id="f-Section">). However, the maintainer of the Debian
661 archive may override this selection to ensure the consistency of
662 the Debian distribution. The <tt>Section</tt> field should be
664 <list compact="compact">
666 <em>section</em> if the package is in the
667 <em>main</em> archive area,
670 <em>area/section</em> if the package is in
671 the <em>contrib</em> or <em>non-free</em>
678 The Debian archive maintainers provide the authoritative
679 list of sections. At present, they are:
680 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
681 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
682 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
683 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
684 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
685 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
686 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
687 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
688 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
689 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
690 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
691 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
692 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
697 <sect id="priorities">
698 <heading>Priorities</heading>
701 Each package should have a <em>priority</em> value, which is
702 included in the package's <em>control record</em>
703 (see <ref id="f-Priority">).
704 This information is used by the Debian package management tools to
705 separate high-priority packages from less-important packages.
709 The following <em>priority levels</em> are recognized by the
710 Debian package management tools.
712 <tag><tt>required</tt></tag>
714 Packages which are necessary for the proper
715 functioning of the system (usually, this means that
716 dpkg functionality depends on these packages).
717 Removing a <tt>required</tt> package may cause your
718 system to become totally broken and you may not even
719 be able to use <prgn>dpkg</prgn> to put things back,
720 so only do so if you know what you are doing. Systems
721 with only the <tt>required</tt> packages are probably
722 unusable, but they do have enough functionality to
723 allow the sysadmin to boot and install more software.
725 <tag><tt>important</tt></tag>
727 Important programs, including those which one would
728 expect to find on any Unix-like system. If the
729 expectation is that an experienced Unix person who
730 found it missing would say "What on earth is going on,
731 where is <prgn>foo</prgn>?", it must be an
732 <tt>important</tt> package.<footnote>
733 This is an important criterion because we are
734 trying to produce, amongst other things, a free
737 Other packages without which the system will not run
738 well or be usable must also have priority
739 <tt>important</tt>. This does
740 <em>not</em> include Emacs, the X Window System, TeX
741 or any other large applications. The
742 <tt>important</tt> packages are just a bare minimum of
743 commonly-expected and necessary tools.
745 <tag><tt>standard</tt></tag>
747 These packages provide a reasonably small but not too
748 limited character-mode system. This is what will be
749 installed by default if the user doesn't select anything
750 else. It doesn't include many large applications.
752 <tag><tt>optional</tt></tag>
754 (In a sense everything that isn't required is
755 optional, but that's not what is meant here.) This is
756 all the software that you might reasonably want to
757 install if you didn't know what it was and don't have
758 specialized requirements. This is a much larger system
759 and includes the X Window System, a full TeX
760 distribution, and many applications. Note that
761 optional packages should not conflict with each other.
763 <tag><tt>extra</tt></tag>
765 This contains all packages that conflict with others
766 with required, important, standard or optional
767 priorities, or are only likely to be useful if you
768 already know what they are or have specialized
769 requirements (such as packages containing only detached
776 Packages must not depend on packages with lower priority
777 values (excluding build-time dependencies). In order to
778 ensure this, the priorities of one or more packages may need
787 <heading>Binary packages</heading>
790 The Debian GNU/Linux distribution is based on the Debian
791 package management system, called <prgn>dpkg</prgn>. Thus,
792 all packages in the Debian distribution must be provided
793 in the <tt>.deb</tt> file format.
797 <heading>The package name</heading>
800 Every package must have a name that's unique within the Debian
805 The package name is included in the control field
806 <tt>Package</tt>, the format of which is described
807 in <ref id="f-Package">.
808 The package name is also included as a part of the file name
809 of the <tt>.deb</tt> file.
814 <heading>The version of a package</heading>
817 Every package has a version number recorded in its
818 <tt>Version</tt> control file field, described in
819 <ref id="f-Version">.
823 The package management system imposes an ordering on version
824 numbers, so that it can tell whether packages are being up- or
825 downgraded and so that package system front end applications
826 can tell whether a package it finds available is newer than
827 the one installed on the system. The version number format
828 has the most significant parts (as far as comparison is
829 concerned) at the beginning.
833 If an upstream package has problematic version numbers they
834 should be converted to a sane form for use in the
835 <tt>Version</tt> field.
839 <heading>Version numbers based on dates</heading>
842 In general, Debian packages should use the same version
843 numbers as the upstream sources.
847 However, in some cases where the upstream version number is
848 based on a date (e.g., a development "snapshot" release) the
849 package management system cannot handle these version
850 numbers without epochs. For example, dpkg will consider
851 "96May01" to be greater than "96Dec24".
855 To prevent having to use epochs for every new upstream
856 version, the date based portion of the version number
857 should be changed to the following format in such cases:
858 "19960501", "19961224". It is up to the maintainer whether
859 they want to bother the upstream maintainer to change
860 the version numbers upstream, too.
864 Note that other version formats based on dates which are
865 parsed correctly by the package management system should
866 <em>not</em> be changed.
870 Native Debian packages (i.e., packages which have been
871 written especially for Debian) whose version numbers include
872 dates should always use the "YYYYMMDD" format.
879 <heading>The maintainer of a package</heading>
882 Every package must have a Debian maintainer (the
883 maintainer may be one person or a group of people
884 reachable from a common email address, such as a mailing
885 list). The maintainer is responsible for ensuring that
886 the package is placed in the appropriate distributions.
890 The maintainer must be specified in the
891 <tt>Maintainer</tt> control field with their correct name
892 and a working email address. If one person maintains
893 several packages, they should try to avoid having
894 different forms of their name and email address in
895 the <tt>Maintainer</tt> fields of those packages.
899 The format of the <tt>Maintainer</tt> control field is
900 described in <ref id="f-Maintainer">.
904 If the maintainer of a package quits from the Debian
905 project, "Debian QA Group"
906 <email>packages@qa.debian.org</email> takes over the
907 maintainer-ship of the package until someone else
908 volunteers for that task. These packages are called
909 <em>orphaned packages</em>.<footnote>
910 The detailed procedure for doing this gracefully can
911 be found in the Debian Developer's Reference,
912 see <ref id="related">.
917 <sect id="descriptions">
918 <heading>The description of a package</heading>
921 Every Debian package must have an extended description
922 stored in the appropriate field of the control record.
923 The technical information about the format of the
924 <tt>Description</tt> field is in <ref id="f-Description">.
928 The description should describe the package (the program) to a
929 user (system administrator) who has never met it before so that
930 they have enough information to decide whether they want to
931 install it. This description should not just be copied verbatim
932 from the program's documentation.
936 Put important information first, both in the synopsis and
937 extended description. Sometimes only the first part of the
938 synopsis or of the description will be displayed. You can
939 assume that there will usually be a way to see the whole
940 extended description.
944 The description should also give information about the
945 significant dependencies and conflicts between this package
946 and others, so that the user knows why these dependencies and
947 conflicts have been declared.
951 Instructions for configuring or using the package should
952 not be included (that is what installation scripts,
953 manual pages, info files, etc., are for). Copyright
954 statements and other administrivia should not be included
955 either (that is what the copyright file is for).
958 <sect1 id="synopsis"><heading>The single line synopsis</heading>
961 The single line synopsis should be kept brief - certainly
966 Do not include the package name in the synopsis line. The
967 display software knows how to display this already, and you
968 do not need to state it. Remember that in many situations
969 the user may only see the synopsis line - make it as
970 informative as you can.
975 <sect1 id="extendeddesc"><heading>The extended description</heading>
978 Do not try to continue the single line synopsis into the
979 extended description. This will not work correctly when
980 the full description is displayed, and makes no sense
981 where only the summary (the single line synopsis) is
986 The extended description should describe what the package
987 does and how it relates to the rest of the system (in terms
988 of, for example, which subsystem it is which part of).
992 The description field needs to make sense to anyone, even
993 people who have no idea about any of the things the
994 package deals with.<footnote>
995 The blurb that comes with a program in its
996 announcements and/or <prgn>README</prgn> files is
997 rarely suitable for use in a description. It is
998 usually aimed at people who are already in the
999 community where the package is used.
1008 <heading>Dependencies</heading>
1011 Every package must specify the dependency information
1012 about other packages that are required for the first to
1017 For example, a dependency entry must be provided for any
1018 shared libraries required by a dynamically-linked executable
1019 binary in a package.
1023 Packages are not required to declare any dependencies they
1024 have on other packages which are marked <tt>Essential</tt>
1025 (see below), and should not do so unless they depend on a
1026 particular version of that package.<footnote>
1028 Essential is needed in part to avoid unresolvable dependency
1029 loops on upgrade. If packages add unnecessary dependencies
1030 on packages in this set, the chances that there
1031 <strong>will</strong> be an unresolvable dependency loop
1032 caused by forcing these Essential packages to be configured
1033 first before they need to be is greatly increased. It also
1034 increases the chances that frontends will be unable to
1035 <strong>calculate</strong> an upgrade path, even if one
1039 Also, functionality is rarely ever removed from the
1040 Essential set, but <em>packages</em> have been removed from
1041 the Essential set when the functionality moved to a
1042 different package. So depending on these packages <em>just
1043 in case</em> they stop being essential does way more harm
1050 Sometimes, a package requires another package to be installed
1051 <em>and</em> configured before it can be installed. In this
1052 case, you must specify a <tt>Pre-Depends</tt> entry for
1057 You should not specify a <tt>Pre-Depends</tt> entry for a
1058 package before this has been discussed on the
1059 <tt>debian-devel</tt> mailing list and a consensus about
1060 doing that has been reached.
1064 The format of the package interrelationship control fields is
1065 described in <ref id="relationships">.
1069 <sect id="virtual_pkg">
1070 <heading>Virtual packages</heading>
1073 Sometimes, there are several packages which offer
1074 more-or-less the same functionality. In this case, it's
1075 useful to define a <em>virtual package</em> whose name
1076 describes that common functionality. (The virtual
1077 packages only exist logically, not physically; that's why
1078 they are called <em>virtual</em>.) The packages with this
1079 particular function will then <em>provide</em> the virtual
1080 package. Thus, any other package requiring that function
1081 can simply depend on the virtual package without having to
1082 specify all possible packages individually.
1086 All packages should use virtual package names where
1087 appropriate, and arrange to create new ones if necessary.
1088 They should not use virtual package names (except privately,
1089 amongst a cooperating group of packages) unless they have
1090 been agreed upon and appear in the list of virtual package
1091 names. (See also <ref id="virtual">)
1095 The latest version of the authoritative list of virtual
1096 package names can be found in the <tt>debian-policy</tt> package.
1097 It is also available from the Debian web mirrors at
1098 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1099 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1103 The procedure for updating the list is described in the preface
1110 <heading>Base system</heading>
1113 The <tt>base system</tt> is a minimum subset of the Debian
1114 GNU/Linux system that is installed before everything else
1115 on a new system. Only very few packages are allowed to form
1116 part of the base system, in order to keep the required disk
1121 The base system consists of all those packages with priority
1122 <tt>required</tt> or <tt>important</tt>. Many of them will
1123 be tagged <tt>essential</tt> (see below).
1128 <heading>Essential packages</heading>
1131 Essential is defined as the minimal set of functionality that
1132 must be available and usable on the system at all times, even
1133 when packages are in an unconfigured (but unpacked) state.
1134 Packages are tagged <tt>essential</tt> for a system using the
1135 <tt>Essential</tt> control file field. The format of the
1136 <tt>Essential</tt> control field is described in <ref
1141 Since these packages cannot be easily removed (one has to
1142 specify an extra <em>force option</em> to
1143 <prgn>dpkg</prgn> to do so), this flag must not be used
1144 unless absolutely necessary. A shared library package
1145 must not be tagged <tt>essential</tt>; dependencies will
1146 prevent its premature removal, and we need to be able to
1147 remove it when it has been superseded.
1151 Since dpkg will not prevent upgrading of other packages
1152 while an <tt>essential</tt> package is in an unconfigured
1153 state, all <tt>essential</tt> packages must supply all of
1154 their core functionality even when unconfigured. If the
1155 package cannot satisfy this requirement it must not be
1156 tagged as essential, and any packages depending on this
1157 package must instead have explicit dependency fields as
1162 Maintainers should take great care in adding any programs,
1163 interfaces, or functionality to <tt>essential</tt> packages.
1164 Packages may assume that functionality provided by
1165 <tt>essential</tt> packages is always available without
1166 declaring explicit dependencies, which means that removing
1167 functionality from the Essential set is very difficult and is
1168 almost never done. Any capability added to an
1169 <tt>essential</tt> package therefore creates an obligation to
1170 support that capability as part of the Essential set in
1175 You must not tag any packages <tt>essential</tt> before
1176 this has been discussed on the <tt>debian-devel</tt>
1177 mailing list and a consensus about doing that has been
1182 <sect id="maintscripts">
1183 <heading>Maintainer Scripts</heading>
1186 The package installation scripts should avoid producing
1187 output which is unnecessary for the user to see and
1188 should rely on <prgn>dpkg</prgn> to stave off boredom on
1189 the part of a user installing many packages. This means,
1190 amongst other things, using the <tt>--quiet</tt> option on
1191 <prgn>install-info</prgn>.
1195 Errors which occur during the execution of an installation
1196 script must be checked and the installation must not
1197 continue after an error.
1201 Note that in general <ref id="scripts"> applies to package
1202 maintainer scripts, too.
1206 You should not use <prgn>dpkg-divert</prgn> on a file
1207 belonging to another package without consulting the
1208 maintainer of that package first.
1212 All packages which supply an instance of a common command
1213 name (or, in general, filename) should generally use
1214 <prgn>update-alternatives</prgn>, so that they may be
1215 installed together. If <prgn>update-alternatives</prgn>
1216 is not used, then each package must use
1217 <tt>Conflicts</tt> to ensure that other packages are
1218 de-installed. (In this case, it may be appropriate to
1219 specify a conflict against earlier versions of something
1220 that previously did not use
1221 <prgn>update-alternatives</prgn>; this is an exception to
1222 the usual rule that versioned conflicts should be
1226 <sect1 id="maintscriptprompt">
1227 <heading>Prompting in maintainer scripts</heading>
1229 Package maintainer scripts may prompt the user if
1230 necessary. Prompting must be done by communicating
1231 through a program, such as <prgn>debconf</prgn>, which
1232 conforms to the Debian Configuration Management
1233 Specification, version 2 or higher.
1237 Packages which are essential, or which are dependencies of
1238 essential packages, may fall back on another prompting method
1239 if no such interface is available when they are executed.
1243 The Debian Configuration Management Specification is included
1244 in the <file>debconf_specification</file> files in the
1245 <package>debian-policy</package> package.
1246 It is also available from the Debian web mirrors at
1247 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1248 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1252 Packages which use the Debian Configuration Management
1253 Specification may contain an additional
1254 <prgn>config</prgn> script and a <tt>templates</tt>
1255 file in their control archive<footnote>
1256 The control.tar.gz inside the .deb.
1257 See <manref name="deb" section="5">.
1259 The <prgn>config</prgn> script might be run before the
1260 <prgn>preinst</prgn> script, and before the package is unpacked
1261 or any of its dependencies or pre-dependencies are satisfied.
1262 Therefore it must work using only the tools present in
1263 <em>essential</em> packages.<footnote>
1264 <package>Debconf</package> or another tool that
1265 implements the Debian Configuration Management
1266 Specification will also be installed, and any
1267 versioned dependencies on it will be satisfied
1268 before preconfiguration begins.
1273 Packages which use the Debian Configuration Management
1274 Specification must allow for translation of their user-visible
1275 messages by using a gettext-based system such as the one
1276 provided by the <package>po-debconf</package> package.
1280 Packages should try to minimize the amount of prompting
1281 they need to do, and they should ensure that the user
1282 will only ever be asked each question once. This means
1283 that packages should try to use appropriate shared
1284 configuration files (such as <file>/etc/papersize</file> and
1285 <file>/etc/news/server</file>), and shared
1286 <package>debconf</package> variables rather than each
1287 prompting for their own list of required pieces of
1292 It also means that an upgrade should not ask the same
1293 questions again, unless the user has used
1294 <tt>dpkg --purge</tt> to remove the package's configuration.
1295 The answers to configuration questions should be stored in an
1296 appropriate place in <file>/etc</file> so that the user can
1297 modify them, and how this has been done should be
1302 If a package has a vitally important piece of
1303 information to pass to the user (such as "don't run me
1304 as I am, you must edit the following configuration files
1305 first or you risk your system emitting badly-formatted
1306 messages"), it should display this in the
1307 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1308 prompt the user to hit return to acknowledge the
1309 message. Copyright messages do not count as vitally
1310 important (they belong in
1311 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1312 neither do instructions on how to use a program (these
1313 should be in on-line documentation, where all the users
1318 Any necessary prompting should almost always be confined
1319 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1320 script. If it is done in the <prgn>postinst</prgn>, it
1321 should be protected with a conditional so that
1322 unnecessary prompting doesn't happen if a package's
1323 installation fails and the <prgn>postinst</prgn> is
1324 called with <tt>abort-upgrade</tt>,
1325 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1335 <heading>Source packages</heading>
1337 <sect id="standardsversion">
1338 <heading>Standards conformance</heading>
1341 Source packages should specify the most recent version number
1342 of this policy document with which your package complied
1343 when it was last updated.
1347 This information may be used to file bug reports
1348 automatically if your package becomes too much out of date.
1352 The version is specified in the <tt>Standards-Version</tt>
1354 The format of the <tt>Standards-Version</tt> field is
1355 described in <ref id="f-Standards-Version">.
1359 You should regularly, and especially if your package has
1360 become out of date, check for the newest Policy Manual
1361 available and update your package, if necessary. When your
1362 package complies with the new standards you should update the
1363 <tt>Standards-Version</tt> source package field and
1364 release it.<footnote>
1365 See the file <file>upgrading-checklist</file> for
1366 information about policy which has changed between
1367 different versions of this document.
1373 <sect id="pkg-relations">
1374 <heading>Package relationships</heading>
1377 Source packages should specify which binary packages they
1378 require to be installed or not to be installed in order to
1379 build correctly. For example, if building a package
1380 requires a certain compiler, then the compiler should be
1381 specified as a build-time dependency.
1385 It is not necessary to explicitly specify build-time
1386 relationships on a minimal set of packages that are always
1387 needed to compile, link and put in a Debian package a
1388 standard "Hello World!" program written in C or C++. The
1389 required packages are called <em>build-essential</em>, and
1390 an informational list can be found in
1391 <file>/usr/share/doc/build-essential/list</file> (which is
1392 contained in the <tt>build-essential</tt>
1395 <list compact="compact">
1397 This allows maintaining the list separately
1398 from the policy documents (the list does not
1399 need the kind of control that the policy
1403 Having a separate package allows one to install
1404 the build-essential packages on a machine, as
1405 well as allowing other packages such as tasks to
1406 require installation of the build-essential
1407 packages using the depends relation.
1410 The separate package allows bug reports against
1411 the list to be categorized separately from
1412 the policy management process in the BTS.
1419 When specifying the set of build-time dependencies, one
1420 should list only those packages explicitly required by the
1421 build. It is not necessary to list packages which are
1422 required merely because some other package in the list of
1423 build-time dependencies depends on them.<footnote>
1424 The reason for this is that dependencies change, and
1425 you should list all those packages, and <em>only</em>
1426 those packages that <em>you</em> need directly. What
1427 others need is their business. For example, if you
1428 only link against <file>libimlib</file>, you will need to
1429 build-depend on <package>libimlib2-dev</package> but
1430 not against any <tt>libjpeg*</tt> packages, even
1431 though <tt>libimlib2-dev</tt> currently depends on
1432 them: installation of <package>libimlib2-dev</package>
1433 will automatically ensure that all of its run-time
1434 dependencies are satisfied.
1439 If build-time dependencies are specified, it must be
1440 possible to build the package and produce working binaries
1441 on a system with only essential and build-essential
1442 packages installed and also those required to satisfy the
1443 build-time relationships (including any implied
1444 relationships). In particular, this means that version
1445 clauses should be used rigorously in build-time
1446 relationships so that one cannot produce bad or
1447 inconsistently configured packages when the relationships
1448 are properly satisfied.
1452 <ref id="relationships"> explains the technical details.
1457 <heading>Changes to the upstream sources</heading>
1460 If changes to the source code are made that are not
1461 specific to the needs of the Debian system, they should be
1462 sent to the upstream authors in whatever form they prefer
1463 so as to be included in the upstream version of the
1468 If you need to configure the package differently for
1469 Debian or for Linux, and the upstream source doesn't
1470 provide a way to do so, you should add such configuration
1471 facilities (for example, a new <prgn>autoconf</prgn> test
1472 or <tt>#define</tt>) and send the patch to the upstream
1473 authors, with the default set to the way they originally
1474 had it. You can then easily override the default in your
1475 <file>debian/rules</file> or wherever is appropriate.
1479 You should make sure that the <prgn>configure</prgn> utility
1480 detects the correct architecture specification string
1481 (refer to <ref id="arch-spec"> for details).
1485 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1486 <prgn>configure</prgn> scripts are used, you should edit the
1487 <file>.in</file> files rather than editing the
1488 <prgn>Makefile</prgn> directly. This allows the user to
1489 reconfigure the package if necessary. You should
1490 <em>not</em> configure the package and edit the generated
1491 <prgn>Makefile</prgn>! This makes it impossible for someone
1492 else to later reconfigure the package without losing the
1498 <sect id="dpkgchangelog">
1499 <heading>Debian changelog: <file>debian/changelog</file></heading>
1502 Changes in the Debian version of the package should be
1503 briefly explained in the Debian changelog file
1504 <file>debian/changelog</file>.<footnote>
1506 Mistakes in changelogs are usually best rectified by
1507 making a new changelog entry rather than "rewriting
1508 history" by editing old changelog entries.
1511 This includes modifications
1512 made in the Debian package compared to the upstream one
1513 as well as other changes and updates to the package.
1515 Although there is nothing stopping an author who is also
1516 the Debian maintainer from using this changelog for all
1517 their changes, it will have to be renamed if the Debian
1518 and upstream maintainers become different people. In such
1519 a case, however, it might be better to maintain the package
1520 as a non-native package.
1525 The format of the <file>debian/changelog</file> allows the
1526 package building tools to discover which version of the package
1527 is being built and find out other release-specific information.
1531 That format is a series of entries like this:
1533 <example compact="compact">
1534 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1536 [optional blank line(s), stripped]
1538 * <var>change details</var>
1539 <var>more change details</var>
1541 [blank line(s), included in output of dpkg-parsechangelog]
1543 * <var>even more change details</var>
1545 [optional blank line(s), stripped]
1547 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1552 <var>package</var> and <var>version</var> are the source
1553 package name and version number.
1557 <var>distribution(s)</var> lists the distributions where
1558 this version should be installed when it is uploaded - it
1559 is copied to the <tt>Distribution</tt> field in the
1560 <file>.changes</file> file. See <ref id="f-Distribution">.
1564 <var>urgency</var> is the value for the <tt>Urgency</tt>
1565 field in the <file>.changes</file> file for the upload
1566 (see <ref id="f-Urgency">). It is not possible to specify
1567 an urgency containing commas; commas are used to separate
1568 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1569 <prgn>dpkg</prgn> changelog format (though there is
1570 currently only one useful <var>keyword</var>,
1575 The change details may in fact be any series of lines
1576 starting with at least two spaces, but conventionally each
1577 change starts with an asterisk and a separating space and
1578 continuation lines are indented so as to bring them in
1579 line with the start of the text above. Blank lines may be
1580 used here to separate groups of changes, if desired.
1584 If this upload resolves bugs recorded in the Bug Tracking
1585 System (BTS), they may be automatically closed on the
1586 inclusion of this package into the Debian archive by
1587 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1588 in the change details.<footnote>
1589 To be precise, the string should match the following
1590 Perl regular expression:
1592 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1594 Then all of the bug numbers listed will be closed by the
1595 archive maintenance script (<prgn>katie</prgn>) using the
1596 <var>version</var> of the changelog entry.
1598 This information is conveyed via the <tt>Closes</tt> field
1599 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1603 The maintainer name and email address used in the changelog
1604 should be the details of the person uploading <em>this</em>
1605 version. They are <em>not</em> necessarily those of the
1606 usual package maintainer. The information here will be
1607 copied to the <tt>Changed-By</tt> field in the
1608 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1609 and then later used to send an acknowledgement when the
1610 upload has been installed.
1614 The <var>date</var> must be in RFC822 format<footnote>
1615 This is generated by <tt>date -R</tt>.
1616 </footnote>; it must include the time zone specified
1617 numerically, with the time zone name or abbreviation
1618 optionally present as a comment in parentheses.
1622 The first "title" line with the package name must start
1623 at the left hand margin. The "trailer" line with the
1624 maintainer and date details must be preceded by exactly
1625 one space. The maintainer details and the date must be
1626 separated by exactly two spaces.
1630 The entire changelog must be encoded in UTF-8.
1634 For more information on placement of the changelog files
1635 within binary packages, please see <ref id="changelogs">.
1639 <sect id="dpkgcopyright">
1640 <heading>Copyright: <file>debian/copyright</file></heading>
1642 Every package must be accompanied by a verbatim copy of
1643 its copyright and distribution license in the file
1644 <file>/usr/share/doc/<var>package</var>/copyright</file>
1645 (see <ref id="copyrightfile"> for further details). Also see
1646 <ref id="pkgcopyright"> for further considerations relayed
1647 to copyrights for packages.
1651 <heading>Error trapping in makefiles</heading>
1654 When <prgn>make</prgn> invokes a command in a makefile
1655 (including your package's upstream makefiles and
1656 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1657 means that <prgn>sh</prgn>'s usual bad error handling
1658 properties apply: if you include a miniature script as one
1659 of the commands in your makefile you'll find that if you
1660 don't do anything about it then errors are not detected
1661 and <prgn>make</prgn> will blithely continue after
1666 Every time you put more than one shell command (this
1667 includes using a loop) in a makefile command you
1668 must make sure that errors are trapped. For
1669 simple compound commands, such as changing directory and
1670 then running a program, using <tt>&&</tt> rather
1671 than semicolon as a command separator is sufficient. For
1672 more complex commands including most loops and
1673 conditionals you should include a separate <tt>set -e</tt>
1674 command at the start of every makefile command that's
1675 actually one of these miniature shell scripts.
1679 <sect id="timestamps">
1680 <heading>Time Stamps</heading>
1682 Maintainers should preserve the modification times of the
1683 upstream source files in a package, as far as is reasonably
1685 The rationale is that there is some information conveyed
1686 by knowing the age of the file, for example, you could
1687 recognize that some documentation is very old by looking
1688 at the modification time, so it would be nice if the
1689 modification time of the upstream source would be
1695 <sect id="restrictions">
1696 <heading>Restrictions on objects in source packages</heading>
1699 The source package may not contain any hard links<footnote>
1701 This is not currently detected when building source
1702 packages, but only when extracting
1706 Hard links may be permitted at some point in the
1707 future, but would require a fair amount of
1710 </footnote>, device special files, sockets or setuid or
1711 setgid files.<footnote>
1712 Setgid directories are allowed.
1717 <sect id="debianrules">
1718 <heading>Main building script: <file>debian/rules</file></heading>
1721 This file must be an executable makefile, and contains the
1722 package-specific recipes for compiling the package and
1723 building binary package(s) from the source.
1727 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1728 so that it can be invoked by saying its name rather than
1729 invoking <prgn>make</prgn> explicitly.
1733 Since an interactive <file>debian/rules</file> script makes it
1734 impossible to auto-compile that package and also makes it
1735 hard for other people to reproduce the same binary
1736 package, all <em>required targets</em> MUST be
1737 non-interactive. At a minimum, required targets are the
1738 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1739 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1740 <em>binary-indep</em>, and <em>build</em>. It also follows
1741 that any target that these targets depend on must also be
1746 The targets are as follows (required unless stated otherwise):
1748 <tag><tt>build</tt></tag>
1751 The <tt>build</tt> target should perform all the
1752 configuration and compilation of the package.
1753 If a package has an interactive pre-build
1754 configuration routine, the Debianized source package
1755 must either be built after this has taken place (so
1756 that the binary package can be built without rerunning
1757 the configuration) or the configuration routine
1758 modified to become non-interactive. (The latter is
1759 preferable if there are architecture-specific features
1760 detected by the configuration routine.)
1764 For some packages, notably ones where the same
1765 source tree is compiled in different ways to produce
1766 two binary packages, the <tt>build</tt> target
1767 does not make much sense. For these packages it is
1768 good enough to provide two (or more) targets
1769 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1770 for each of the ways of building the package, and a
1771 <tt>build</tt> target that does nothing. The
1772 <tt>binary</tt> target will have to build the
1773 package in each of the possible ways and make the
1774 binary package out of each.
1778 The <tt>build</tt> target must not do anything
1779 that might require root privilege.
1783 The <tt>build</tt> target may need to run the
1784 <tt>clean</tt> target first - see below.
1788 When a package has a configuration and build routine
1789 which takes a long time, or when the makefiles are
1790 poorly designed, or when <tt>build</tt> needs to
1791 run <tt>clean</tt> first, it is a good idea to
1792 <tt>touch build</tt> when the build process is
1793 complete. This will ensure that if <tt>debian/rules
1794 build</tt> is run again it will not rebuild the whole
1796 Another common way to do this is for <tt>build</tt>
1797 to depend on <prgn>build-stamp</prgn> and to do
1798 nothing else, and for the <prgn>build-stamp</prgn>
1799 target to do the building and to <tt>touch
1800 build-stamp</tt> on completion. This is
1801 especially useful if the build routine creates a
1802 file or directory called <tt>build</tt>; in such a
1803 case, <tt>build</tt> will need to be listed as
1804 a phony target (i.e., as a dependency of the
1805 <tt>.PHONY</tt> target). See the documentation of
1806 <prgn>make</prgn> for more information on phony
1812 <tag><tt>build-arch</tt> (optional),
1813 <tt>build-indep</tt> (optional)
1817 A package may also provide both of the targets
1818 <tt>build-arch</tt> and <tt>build-indep</tt>.
1819 The <tt>build-arch</tt> target, if provided, should
1820 perform all the configuration and compilation required
1821 for producing all architecture-dependant binary packages
1822 (those packages for which the body of the
1823 <tt>Architecture</tt> field in <tt>debian/control</tt>
1824 is not <tt>all</tt>).
1825 Similarly, the <tt>build-indep</tt> target, if
1826 provided, should perform all the configuration and
1827 compilation required for producing all
1828 architecture-independent binary packages
1829 (those packages for which the body of the
1830 <tt>Architecture</tt> field in <tt>debian/control</tt>
1832 The <tt>build</tt> target should depend on those of the
1833 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1834 are provided in the rules file.
1838 If one or both of the targets <tt>build-arch</tt> and
1839 <tt>build-indep</tt> are not provided, then invoking
1840 <file>debian/rules</file> with one of the not-provided
1841 targets as arguments should produce a exit status code
1842 of 2. Usually this is provided automatically by make
1843 if the target is missing.
1847 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1848 must not do anything that might require root privilege.
1852 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1853 <tt>binary-indep</tt>
1857 The <tt>binary</tt> target must be all that is
1858 necessary for the user to build the binary package(s)
1859 produced from this source package. It is
1860 split into two parts: <prgn>binary-arch</prgn> builds
1861 the binary packages which are specific to a particular
1862 architecture, and <tt>binary-indep</tt> builds
1863 those which are not.
1866 <tt>binary</tt> may be (and commonly is) a target with
1867 no commands which simply depends on
1868 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1871 Both <tt>binary-*</tt> targets should depend on the
1872 <tt>build</tt> target, or on the appropriate
1873 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1874 provided, so that the package is built if it has not
1875 been already. It should then create the relevant
1876 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1877 make their control files and <prgn>dpkg-deb</prgn> to
1878 build them and place them in the parent of the top
1883 Both the <tt>binary-arch</tt> and
1884 <tt>binary-indep</tt> targets <em>must</em> exist.
1885 If one of them has nothing to do (which will always be
1886 the case if the source generates only a single binary
1887 package, whether architecture-dependent or not), it
1888 must still exist and must always succeed.
1892 The <tt>binary</tt> targets must be invoked as
1894 The <prgn>fakeroot</prgn> package often allows one
1895 to build a package correctly even without being
1901 <tag><tt>clean</tt></tag>
1904 This must undo any effects that the <tt>build</tt>
1905 and <tt>binary</tt> targets may have had, except
1906 that it should leave alone any output files created in
1907 the parent directory by a run of a <tt>binary</tt>
1912 If a <tt>build</tt> file is touched at the end of
1913 the <tt>build</tt> target, as suggested above, it
1914 should be removed as the first action that
1915 <tt>clean</tt> performs, so that running
1916 <tt>build</tt> again after an interrupted
1917 <tt>clean</tt> doesn't think that everything is
1922 The <tt>clean</tt> target may need to be
1923 invoked as root if <tt>binary</tt> has been
1924 invoked since the last <tt>clean</tt>, or if
1925 <tt>build</tt> has been invoked as root (since
1926 <tt>build</tt> may create directories, for
1931 <tag><tt>get-orig-source</tt> (optional)</tag>
1934 This target fetches the most recent version of the
1935 original source package from a canonical archive site
1936 (via FTP or WWW, for example), does any necessary
1937 rearrangement to turn it into the original source
1938 tar file format described below, and leaves it in the
1943 This target may be invoked in any directory, and
1944 should take care to clean up any temporary files it
1949 This target is optional, but providing it if
1950 possible is a good idea.
1954 <tag><tt>patch</tt> (optional)</tag>
1957 This target performs whatever additional actions are
1958 required to make the source ready for editing (unpacking
1959 additional upstream archives, applying patches, etc.).
1960 It is recommended to be implemented for any package where
1961 <tt>dpkg-source -x</tt> does not result in source ready
1962 for additional modification. See
1963 <ref id="readmesource">.
1969 The <tt>build</tt>, <tt>binary</tt> and
1970 <tt>clean</tt> targets must be invoked with the current
1971 directory being the package's top-level directory.
1976 Additional targets may exist in <file>debian/rules</file>,
1977 either as published or undocumented interfaces or for the
1978 package's internal use.
1982 The architectures we build on and build for are determined
1983 by <prgn>make</prgn> variables using the utility
1984 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1985 You can determine the
1986 Debian architecture and the GNU style architecture
1987 specification string for the build machine (the machine type
1988 we are building on) as well as for the host machine (the
1989 machine type we are building for). Here is a list of
1990 supported <prgn>make</prgn> variables:
1991 <list compact="compact">
1993 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1996 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
1999 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2002 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2003 specification string)
2006 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2007 <tt>DEB_*_GNU_TYPE</tt>)
2010 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2011 <tt>DEB_*_GNU_TYPE</tt>)
2013 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2014 the build machine or <tt>HOST</tt> for specification of the
2019 Backward compatibility can be provided in the rules file
2020 by setting the needed variables to suitable default
2021 values; please refer to the documentation of
2022 <prgn>dpkg-architecture</prgn> for details.
2026 It is important to understand that the <tt>DEB_*_ARCH</tt>
2027 string only determines which Debian architecture we are
2028 building on or for. It should not be used to get the CPU
2029 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2030 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2031 GNU style variables should generally only be used with upstream
2035 <sect1 id="debianrules-options">
2036 <heading><file>debian/rules</file> and
2037 <tt>DEB_BUILD_OPTIONS</tt></heading>
2040 Supporting the standardized environment variable
2041 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2042 contain several flags to change how a package is compiled and
2043 built. Each flag must be in the form <var>flag</var> or
2044 <var>flag</var>=<var>options</var>. If multiple flags are
2045 given, they must be separated by whitespace.<footnote>
2046 Some packages support any delimiter, but whitespace is the
2047 easiest to parse inside a makefile and avoids ambiguity with
2048 flag values that contain commas.
2050 <var>flag</var> must start with a lowercase letter
2051 (<tt>a-z</tt>) and consist only of lowercase letters,
2052 numbers (<tt>0-9</tt>), and the characters
2053 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2054 <var>options</var> must not contain whitespace. The same
2055 tag should not be given multiple times with conflicting
2056 values. Package maintainers may assume that
2057 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2061 The meaning of the following tags has been standardized:
2065 This tag says to not run any build-time test suite
2066 provided by the package.
2070 The presence of this tag means that the package should
2071 be compiled with a minimum of optimization. For C
2072 programs, it is best to add <tt>-O0</tt> to
2073 <tt>CFLAGS</tt> (although this is usually the default).
2074 Some programs might fail to build or run at this level
2075 of optimization; it may be necessary to use
2076 <tt>-O1</tt>, for example.
2080 This tag means that the debugging symbols should not be
2081 stripped from the binary during installation, so that
2082 debugging information may be included in the package.
2084 <tag>parallel=n</tag>
2086 This tag means that the package should be built using up
2087 to <tt>n</tt> parallel processes if the package build
2088 system supports this.<footnote>
2089 Packages built with <tt>make</tt> can often implement
2090 this by passing the <tt>-j</tt><var>n</var> option to
2093 If the package build system does not support parallel
2094 builds, this string must be ignored. If the package
2095 build system only supports a lower level of concurrency
2096 than <var>n</var>, the package should be built using as
2097 many parallel processes as the package build system
2098 supports. It is up to the package maintainer to decide
2099 whether the package build times are long enough and the
2100 package build system is robust enough to make supporting
2101 parallel builds worthwhile.
2107 Unknown flags must be ignored by <file>debian/rules</file>.
2111 The following makefile snippet is an example of how one may
2112 implement the build options; you will probably have to
2113 massage this example in order to make it work for your
2115 <example compact="compact">
2118 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2119 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2120 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2121 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2123 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2128 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2129 INSTALL_PROGRAM += -s
2131 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2132 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2133 MAKEFLAGS += -j$(NUMJOBS)
2138 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2139 # Code to run the package test suite.
2146 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2147 <sect id="substvars">
2148 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2151 When <prgn>dpkg-gencontrol</prgn>,
2152 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2153 generate control files they perform variable substitutions
2154 on their output just before writing it. Variable
2155 substitutions have the form <tt>${<var>variable</var>}</tt>.
2156 The optional file <file>debian/substvars</file> contains
2157 variable substitutions to be used; variables can also be set
2158 directly from <file>debian/rules</file> using the <tt>-V</tt>
2159 option to the source packaging commands, and certain
2160 predefined variables are also available.
2164 The <file>debian/substvars</file> file is usually generated and
2165 modified dynamically by <file>debian/rules</file> targets, in
2166 which case it must be removed by the <tt>clean</tt> target.
2170 See <manref name="deb-substvars" section="5"> for full
2171 details about source variable substitutions, including the
2172 format of <file>debian/substvars</file>.</p>
2175 <sect id="debianwatch">
2176 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2179 This is an optional, recommended control file for the
2180 <tt>uscan</tt> utility which defines how to automatically
2181 scan ftp or http sites for newly available updates of the
2182 package. This is used by <url id="
2183 http://dehs.alioth.debian.org/"> and other Debian QA tools
2184 to help with quality control and maintenance of the
2185 distribution as a whole.
2190 <sect id="debianfiles">
2191 <heading>Generated files list: <file>debian/files</file></heading>
2194 This file is not a permanent part of the source tree; it
2195 is used while building packages to record which files are
2196 being generated. <prgn>dpkg-genchanges</prgn> uses it
2197 when it generates a <file>.changes</file> file.
2201 It should not exist in a shipped source package, and so it
2202 (and any backup files or temporary files such as
2203 <file>files.new</file><footnote>
2204 <file>files.new</file> is used as a temporary file by
2205 <prgn>dpkg-gencontrol</prgn> and
2206 <prgn>dpkg-distaddfile</prgn> - they write a new
2207 version of <tt>files</tt> here before renaming it,
2208 to avoid leaving a corrupted copy if an error
2210 </footnote>) should be removed by the
2211 <tt>clean</tt> target. It may also be wise to
2212 ensure a fresh start by emptying or removing it at the
2213 start of the <tt>binary</tt> target.
2217 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2218 package, it adds an entry to <file>debian/files</file> for the
2219 <file>.deb</file> file that will be created when <tt>dpkg-deb
2220 --build</tt> is run for that binary package. So for most
2221 packages all that needs to be done with this file is to
2222 delete it in the <tt>clean</tt> target.
2226 If a package upload includes files besides the source
2227 package and any binary packages whose control files were
2228 made with <prgn>dpkg-gencontrol</prgn> then they should be
2229 placed in the parent of the package's top-level directory
2230 and <prgn>dpkg-distaddfile</prgn> should be called to add
2231 the file to the list in <file>debian/files</file>.</p>
2234 <sect id="embeddedfiles">
2235 <heading>Convenience copies of code</heading>
2238 Some software packages include in their distribution convenience
2239 copies of code from other software packages, generally so that
2240 users compiling from source don't have to download multiple
2241 packages. Debian packages should not make use of these
2242 convenience copies unless the included package is explicitly
2243 intended to be used in this way.<footnote>
2244 For example, parts of the GNU build system work like this.
2246 If the included code is already in the Debian archive in the
2247 form of a library, the Debian packaging should ensure that
2248 binary packages reference the libraries already in Debian and
2249 the convenience copy is not used. If the included code is not
2250 already in Debian, it should be packaged separately as a
2251 prerequisite if possible.
2253 Having multiple copies of the same code in Debian is
2254 inefficient, often creates either static linking or shared
2255 library conflicts, and, most importantly, increases the
2256 difficulty of handling security vulnerabilities in the
2262 <sect id="readmesource">
2263 <heading>Source package handling:
2264 <file>debian/README.source</file></heading>
2267 If running <prgn>dpkg-source -x</prgn> on a source package
2268 doesn't produce the source of the package, ready for editing,
2269 and allow one to make changes and run
2270 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2271 without taking any additional steps, creating a
2272 <file>debian/README.source</file> documentation file is
2273 recommended. This file should explain how to do all of the
2276 <item>Generate the fully patched source, in a form ready for
2277 editing, that would be built to create Debian
2278 packages. Doing this with a <tt>patch</tt> target in
2279 <file>debian/rules</file> is recommended; see
2280 <ref id="debianrules">.</item>
2281 <item>Modify the source and save those modifications so that
2282 they will be applied when building the package.</item>
2283 <item>Remove source modifications that are currently being
2284 applied when building the package.</item>
2285 <item>Optionally, document what steps are necessary to
2286 upgrade the Debian source package to a new upstream version,
2287 if applicable.</item>
2289 This explanation should include specific commands and mention
2290 any additional required Debian packages. It should not assume
2291 familiarity with any specific Debian packaging system or patch
2296 This explanation may refer to a documentation file installed by
2297 one of the package's build dependencies provided that the
2298 referenced documentation clearly explains these tasks and is not
2299 a general reference manual.
2303 <file>debian/README.source</file> may also include any other
2304 information that would be helpful to someone modifying the
2305 source package. Even if the package doesn't fit the above
2306 description, maintainers are encouraged to document in a
2307 <file>debian/README.source</file> file any source package with a
2308 particularly complex or unintuitive source layout or build
2309 system (for example, a package that builds the same source
2310 multiple times to generate different binary packages).
2316 <chapt id="controlfields">
2317 <heading>Control files and their fields</heading>
2320 The package management system manipulates data represented in
2321 a common format, known as <em>control data</em>, stored in
2322 <em>control files</em>.
2323 Control files are used for source packages, binary packages and
2324 the <file>.changes</file> files which control the installation
2325 of uploaded files<footnote>
2326 <prgn>dpkg</prgn>'s internal databases are in a similar
2331 <sect id="controlsyntax">
2332 <heading>Syntax of control files</heading>
2335 A control file consists of one or more paragraphs of
2337 The paragraphs are also sometimes referred to as stanzas.
2339 The paragraphs are separated by blank lines. Some control
2340 files allow only one paragraph; others allow several, in
2341 which case each paragraph usually refers to a different
2342 package. (For example, in source packages, the first
2343 paragraph refers to the source package, and later paragraphs
2344 refer to binary packages generated from the source.)
2348 Each paragraph consists of a series of data fields; each
2349 field consists of the field name, followed by a colon and
2350 then the data/value associated with that field. It ends at
2351 the end of the (logical) line. Horizontal whitespace
2352 (spaces and tabs) may occur immediately before or after the
2353 value and is ignored there; it is conventional to put a
2354 single space after the colon. For example, a field might
2356 <example compact="compact">
2359 the field name is <tt>Package</tt> and the field value
2364 Many fields' values may span several lines; in this case
2365 each continuation line must start with a space or a tab.
2366 Any trailing spaces or tabs at the end of individual
2367 lines of a field value are ignored.
2371 In fields where it is specified that lines may not wrap,
2372 only a single line of data is allowed and whitespace is not
2373 significant in a field body. Whitespace must not appear
2374 inside names (of packages, architectures, files or anything
2375 else) or version numbers, or between the characters of
2376 multi-character version relationships.
2380 Field names are not case-sensitive, but it is usual to
2381 capitalize the field names using mixed case as shown below.
2385 Blank lines, or lines consisting only of spaces and tabs,
2386 are not allowed within field values or between fields - that
2387 would mean a new paragraph.
2391 All control files must be encoded in UTF-8.
2395 <sect id="sourcecontrolfiles">
2396 <heading>Source package control files -- <file>debian/control</file></heading>
2399 The <file>debian/control</file> file contains the most vital
2400 (and version-independent) information about the source package
2401 and about the binary packages it creates.
2405 The first paragraph of the control file contains information about
2406 the source package in general. The subsequent sets each describe a
2407 binary package that the source tree builds.
2411 The fields in the general paragraph (the first one, for the source
2414 <list compact="compact">
2415 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2416 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2417 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2418 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2419 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2420 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2421 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2422 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2427 The fields in the binary package paragraphs are:
2429 <list compact="compact">
2430 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2431 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2432 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2433 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2434 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2435 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2436 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2437 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2442 The syntax and semantics of the fields are described below.
2448 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2449 generate control files for binary packages (see below), by
2450 <prgn>dpkg-genchanges</prgn> to generate the
2451 <tt>.changes</tt> file to accompany the upload, and by
2452 <prgn>dpkg-source</prgn> when it creates the
2453 <file>.dsc</file> source control file as part of a source
2454 archive. Many fields are permitted to span multiple lines in
2455 <file>debian/control</file> but not in any other control
2456 file. These tools are responsible for removing the line
2457 breaks from such fields when using fields from
2458 <file>debian/control</file> to generate other control files.
2462 The fields here may contain variable references - their
2463 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2464 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2465 when they generate output control files.
2466 See <ref id="substvars"> for details.
2470 In addition to the control file syntax described <qref
2471 id="controlsyntax">above</qref>, this file may also contain
2472 comment lines starting with <tt>#</tt> without any preceding
2473 whitespace. All such lines are ignored, even in the middle of
2474 continuation lines for a multiline field, and do not end a
2480 <sect id="binarycontrolfiles">
2481 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2484 The <file>DEBIAN/control</file> file contains the most vital
2485 (and version-dependent) information about a binary package.
2489 The fields in this file are:
2491 <list compact="compact">
2492 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2493 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2494 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2495 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2496 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2497 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2498 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2499 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2500 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2501 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2502 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2503 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2508 <sect id="debiansourcecontrolfiles">
2509 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2512 This file contains a series of fields, identified and
2513 separated just like the fields in the control file of
2514 a binary package. The fields are listed below; their
2515 syntax is described above, in <ref id="pkg-controlfields">.
2517 <list compact="compact">
2518 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2519 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2520 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2522 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2523 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2524 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2525 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2526 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2527 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2528 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2533 The source package control file is generated by
2534 <prgn>dpkg-source</prgn> when it builds the source
2535 archive, from other files in the source package,
2536 described above. When unpacking, it is checked against
2537 the files and directories in the other parts of the
2543 <sect id="debianchangesfiles">
2544 <heading>Debian changes files -- <file>.changes</file></heading>
2547 The .changes files are used by the Debian archive maintenance
2548 software to process updates to packages. They contain one
2549 paragraph which contains information from the
2550 <tt>debian/control</tt> file and other data about the
2551 source package gathered via <tt>debian/changelog</tt>
2552 and <tt>debian/rules</tt>.
2556 The fields in this file are:
2558 <list compact="compact">
2559 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2560 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2561 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2562 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2563 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2564 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2567 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2569 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2570 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2571 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2577 <sect id="controlfieldslist">
2578 <heading>List of fields</heading>
2580 <sect1 id="f-Source">
2581 <heading><tt>Source</tt></heading>
2584 This field identifies the source package name.
2588 In <file>debian/control</file> or a <file>.dsc</file> file,
2589 this field must contain only the name of the source package.
2593 In a binary package control file or a <file>.changes</file>
2594 file, the source package name may be followed by a version
2595 number in parentheses<footnote>
2596 It is customary to leave a space after the package name
2597 if a version number is specified.
2599 This version number may be omitted (and is, by
2600 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2601 the <tt>Version</tt> field of the binary package in
2602 question. The field itself may be omitted from a binary
2603 package control file when the source package has the same
2604 name and version as the binary package.
2608 Package names (both source and binary,
2609 see <ref id="f-Package">) must consist only of lower case
2610 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2611 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2612 (<tt>.</tt>). They must be at least two characters long and
2613 must start with an alphanumeric character.
2617 <sect1 id="f-Maintainer">
2618 <heading><tt>Maintainer</tt></heading>
2621 The package maintainer's name and email address. The name
2622 should come first, then the email address inside angle
2623 brackets <tt><></tt> (in RFC822 format).
2627 If the maintainer's name contains a full stop then the
2628 whole field will not work directly as an email address due
2629 to a misfeature in the syntax specified in RFC822; a
2630 program using this field as an address must check for this
2631 and correct the problem if necessary (for example by
2632 putting the name in round brackets and moving it to the
2633 end, and bringing the email address forward).
2637 <sect1 id="f-Uploaders">
2638 <heading><tt>Uploaders</tt></heading>
2641 List of the names and email addresses of co-maintainers of
2642 the package, if any. If the package has other maintainers
2643 beside the one named in the
2644 <qref id="f-Maintainer">Maintainer field</qref>, their
2645 names and email addresses should be listed here. The
2646 format is the same as that of the Maintainer tag, and
2647 multiple entries should be comma separated. Currently,
2648 this field is restricted to a single line of data. This
2649 is an optional field.
2652 Any parser that interprets the Uploaders field in
2653 <file>debian/control</file> must permit it to span multiple
2654 lines. Line breaks in an Uploaders field that spans multiple
2655 lines are not significant and the semantics of the field are
2656 the same as if the line breaks had not been present.
2660 <sect1 id="f-Changed-By">
2661 <heading><tt>Changed-By</tt></heading>
2664 The name and email address of the person who changed the
2665 said package. Usually the name of the maintainer.
2666 All the rules for the Maintainer field apply here, too.
2670 <sect1 id="f-Section">
2671 <heading><tt>Section</tt></heading>
2674 This field specifies an application area into which the package
2675 has been classified. See <ref id="subsections">.
2679 When it appears in the <file>debian/control</file> file,
2680 it gives the value for the subfield of the same name in
2681 the <tt>Files</tt> field of the <file>.changes</file> file.
2682 It also gives the default for the same field in the binary
2687 <sect1 id="f-Priority">
2688 <heading><tt>Priority</tt></heading>
2691 This field represents how important that it is that the user
2692 have the package installed. See <ref id="priorities">.
2696 When it appears in the <file>debian/control</file> file,
2697 it gives the value for the subfield of the same name in
2698 the <tt>Files</tt> field of the <file>.changes</file> file.
2699 It also gives the default for the same field in the binary
2704 <sect1 id="f-Package">
2705 <heading><tt>Package</tt></heading>
2708 The name of the binary package.
2712 Binary package names must follow the same syntax and
2713 restrictions as source package names. See <ref id="f-Source">
2718 <sect1 id="f-Architecture">
2719 <heading><tt>Architecture</tt></heading>
2722 Depending on context and the control file used, the
2723 <tt>Architecture</tt> field can include the following sets of
2726 <item>A unique single word identifying a Debian machine
2727 architecture as described in <ref id="arch-spec">.
2728 <item><tt>all</tt>, which indicates an
2729 architecture-independent package.
2730 <item><tt>any</tt>, which indicates a package available
2731 for building on any architecture.
2732 <item><tt>source</tt>, which indicates a source package.
2737 In the main <file>debian/control</file> file in the source
2738 package, this field may contain the special value
2739 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2740 architectures separated by spaces. If <tt>any</tt> or
2741 <tt>all</tt> appear, they must be the entire contents of the
2742 field. Most packages will use either <tt>any</tt> or
2743 <tt>all</tt>. Specifying a specific list of architectures is
2744 for the minority of cases where a program is not portable or
2745 is not useful on some architectures, and where possible the
2746 program should be made portable instead.
2750 In the source package control file <file>.dsc</file>, this
2751 field may contain either the special value <tt>any</tt> or a
2752 list of architectures separated by spaces. If a list is given,
2753 it may include (or consist solely of) the special value
2754 <tt>all</tt>. In other words, in <file>.dsc</file> files
2755 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2756 in combination with specific architectures. The
2757 <tt>Architecture</tt> field in the source package control file
2758 <file>.dsc</file> is generally constructed from the
2759 <tt>Architecture</tt> fields in the
2760 <file>debian/control</file> in the source package.
2764 Specifying <tt>any</tt> indicates that the source package
2765 isn't dependent on any particular architecture and should
2766 compile fine on any one. The produced binary package(s)
2767 will either be specific to whatever the current build
2768 architecture is or will be architecture-independent.
2772 Specifying only <tt>all</tt> indicates that the source package
2773 will only build architecture-independent packages. If this is
2774 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2775 <tt>any</tt> implies that the source package will build at
2776 least one architecture-dependent package.
2780 Specifying a list of architectures indicates that the source
2781 will build an architecture-dependent package, and will only
2782 work correctly on the listed architectures. If the source
2783 package also builds at least one architecture-independent
2784 package, <tt>all</tt> will also be included in the list.
2788 In a <file>.changes</file> file, the <tt>Architecture</tt>
2789 field lists the architecture(s) of the package(s)
2790 currently being uploaded. This will be a list; if the
2791 source for the package is also being uploaded, the special
2792 entry <tt>source</tt> is also present. <tt>all</tt> will be
2793 present if any architecture-independent packages are being
2794 uploaded. <tt>any</tt> may never occur in the
2795 <tt>Architecture</tt> field in the <file>.changes</file>
2800 See <ref id="debianrules"> for information how to get the
2801 architecture for the build process.
2805 <sect1 id="f-Essential">
2806 <heading><tt>Essential</tt></heading>
2809 This is a boolean field which may occur only in the
2810 control file of a binary package or in a per-package fields
2811 paragraph of a main source control data file.
2815 If set to <tt>yes</tt> then the package management system
2816 will refuse to remove the package (upgrading and replacing
2817 it is still possible). The other possible value is <tt>no</tt>,
2818 which is the same as not having the field at all.
2823 <heading>Package interrelationship fields:
2824 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2825 <tt>Recommends</tt>, <tt>Suggests</tt>,
2826 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2827 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2831 These fields describe the package's relationships with
2832 other packages. Their syntax and semantics are described
2833 in <ref id="relationships">.</p>
2836 <sect1 id="f-Standards-Version">
2837 <heading><tt>Standards-Version</tt></heading>
2840 The most recent version of the standards (the policy
2841 manual and associated texts) with which the package
2846 The version number has four components: major and minor
2847 version number and major and minor patch level. When the
2848 standards change in a way that requires every package to
2849 change the major number will be changed. Significant
2850 changes that will require work in many packages will be
2851 signaled by a change to the minor number. The major patch
2852 level will be changed for any change to the meaning of the
2853 standards, however small; the minor patch level will be
2854 changed when only cosmetic, typographical or other edits
2855 are made which neither change the meaning of the document
2856 nor affect the contents of packages.
2860 Thus only the first three components of the policy version
2861 are significant in the <em>Standards-Version</em> control
2862 field, and so either these three components or the all
2863 four components may be specified.<footnote>
2864 In the past, people specified the full version number
2865 in the Standards-Version field, for example "2.3.0.0".
2866 Since minor patch-level changes don't introduce new
2867 policy, it was thought it would be better to relax
2868 policy and only require the first 3 components to be
2869 specified, in this example "2.3.0". All four
2870 components may still be used if someone wishes to do so.
2876 <sect1 id="f-Version">
2877 <heading><tt>Version</tt></heading>
2880 The version number of a package. The format is:
2881 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2885 The three components here are:
2887 <tag><var>epoch</var></tag>
2890 This is a single (generally small) unsigned integer. It
2891 may be omitted, in which case zero is assumed. If it is
2892 omitted then the <var>upstream_version</var> may not
2897 It is provided to allow mistakes in the version numbers
2898 of older versions of a package, and also a package's
2899 previous version numbering schemes, to be left behind.
2903 <tag><var>upstream_version</var></tag>
2906 This is the main part of the version number. It is
2907 usually the version number of the original ("upstream")
2908 package from which the <file>.deb</file> file has been made,
2909 if this is applicable. Usually this will be in the same
2910 format as that specified by the upstream author(s);
2911 however, it may need to be reformatted to fit into the
2912 package management system's format and comparison
2917 The comparison behavior of the package management system
2918 with respect to the <var>upstream_version</var> is
2919 described below. The <var>upstream_version</var>
2920 portion of the version number is mandatory.
2924 The <var>upstream_version</var> may contain only
2925 alphanumerics<footnote>
2926 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2928 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2929 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2930 tilde) and should start with a digit. If there is no
2931 <var>debian_revision</var> then hyphens are not allowed;
2932 if there is no <var>epoch</var> then colons are not
2937 <tag><var>debian_revision</var></tag>
2940 This part of the version number specifies the version of
2941 the Debian package based on the upstream version. It
2942 may contain only alphanumerics and the characters
2943 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2944 tilde) and is compared in the same way as the
2945 <var>upstream_version</var> is.
2949 It is optional; if it isn't present then the
2950 <var>upstream_version</var> may not contain a hyphen.
2951 This format represents the case where a piece of
2952 software was written specifically to be turned into a
2953 Debian package, and so there is only one "debianisation"
2954 of it and therefore no revision indication is required.
2958 It is conventional to restart the
2959 <var>debian_revision</var> at <tt>1</tt> each time the
2960 <var>upstream_version</var> is increased.
2964 The package management system will break the version
2965 number apart at the last hyphen in the string (if there
2966 is one) to determine the <var>upstream_version</var> and
2967 <var>debian_revision</var>. The absence of a
2968 <var>debian_revision</var> is equivalent to a
2969 <var>debian_revision</var> of <tt>0</tt>.
2976 When comparing two version numbers, first the <var>epoch</var>
2977 of each are compared, then the <var>upstream_version</var> if
2978 <var>epoch</var> is equal, and then <var>debian_revision</var>
2979 if <var>upstream_version</var> is also equal.
2980 <var>epoch</var> is compared numerically. The
2981 <var>upstream_version</var> and <var>debian_revision</var>
2982 parts are compared by the package management system using the
2983 following algorithm:
2987 The strings are compared from left to right.
2991 First the initial part of each string consisting entirely of
2992 non-digit characters is determined. These two parts (one of
2993 which may be empty) are compared lexically. If a difference
2994 is found it is returned. The lexical comparison is a
2995 comparison of ASCII values modified so that all the letters
2996 sort earlier than all the non-letters and so that a tilde
2997 sorts before anything, even the end of a part. For example,
2998 the following parts are in sorted order from earliest to
2999 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3000 <tt>a</tt>.<footnote>
3001 One common use of <tt>~</tt> is for upstream pre-releases.
3002 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3003 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3008 Then the initial part of the remainder of each string which
3009 consists entirely of digit characters is determined. The
3010 numerical values of these two parts are compared, and any
3011 difference found is returned as the result of the comparison.
3012 For these purposes an empty string (which can only occur at
3013 the end of one or both version strings being compared) counts
3018 These two steps (comparing and removing initial non-digit
3019 strings and initial digit strings) are repeated until a
3020 difference is found or both strings are exhausted.
3024 Note that the purpose of epochs is to allow us to leave behind
3025 mistakes in version numbering, and to cope with situations
3026 where the version numbering scheme changes. It is
3027 <em>not</em> intended to cope with version numbers containing
3028 strings of letters which the package management system cannot
3029 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3030 silly orderings (the author of this manual has heard of a
3031 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3032 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3033 <tt>2</tt> and so forth).
3037 <sect1 id="f-Description">
3038 <heading><tt>Description</tt></heading>
3041 In a source or binary control file, the <tt>Description</tt>
3042 field contains a description of the binary package, consisting
3043 of two parts, the synopsis or the short description, and the
3044 long description. The field's format is as follows:
3049 Description: <single line synopsis>
3050 <extended description over several lines>
3055 The lines in the extended description can have these formats:
3061 Those starting with a single space are part of a paragraph.
3062 Successive lines of this form will be word-wrapped when
3063 displayed. The leading space will usually be stripped off.
3067 Those starting with two or more spaces. These will be
3068 displayed verbatim. If the display cannot be panned
3069 horizontally, the displaying program will line wrap them "hard"
3070 (i.e., without taking account of word breaks). If it can they
3071 will be allowed to trail off to the right. None, one or two
3072 initial spaces may be deleted, but the number of spaces
3073 deleted from each line will be the same (so that you can have
3074 indenting work correctly, for example).
3078 Those containing a single space followed by a single full stop
3079 character. These are rendered as blank lines. This is the
3080 <em>only</em> way to get a blank line<footnote>
3081 Completely empty lines will not be rendered as blank lines.
3082 Instead, they will cause the parser to think you're starting
3083 a whole new record in the control file, and will therefore
3084 likely abort with an error.
3089 Those containing a space, a full stop and some more characters.
3090 These are for future expansion. Do not use them.
3096 Do not use tab characters. Their effect is not predictable.
3100 See <ref id="descriptions"> for further information on this.
3104 In a <file>.changes</file> file, the <tt>Description</tt> field
3105 contains a summary of the descriptions for the packages being
3110 The part of the field before the first newline is empty;
3111 thereafter each line has the name of a binary package and
3112 the summary description line from that binary package.
3113 Each line is indented by one space.
3118 <sect1 id="f-Distribution">
3119 <heading><tt>Distribution</tt></heading>
3122 In a <file>.changes</file> file or parsed changelog output
3123 this contains the (space-separated) name(s) of the
3124 distribution(s) where this version of the package should
3125 be installed. Valid distributions are determined by the
3126 archive maintainers.<footnote>
3127 Example distribution names in the Debian archive used in
3128 <file>.changes</file> files are:
3129 <taglist compact="compact">
3130 <tag><em>unstable</em></tag>
3132 This distribution value refers to the
3133 <em>developmental</em> part of the Debian distribution
3134 tree. Most new packages, new upstream versions of
3135 packages and bug fixes go into the <em>unstable</em>
3139 <tag><em>experimental</em></tag>
3141 The packages with this distribution value are deemed
3142 by their maintainers to be high risk. Oftentimes they
3143 represent early beta or developmental packages from
3144 various sources that the maintainers want people to
3145 try, but are not ready to be a part of the other parts
3146 of the Debian distribution tree.
3151 Others are used for updating stable releases or for
3152 security uploads. More information is available in the
3153 Debian Developer's Reference, section "The Debian
3157 The Debian archive software only supports listing a single
3158 distribution. Migration of packages to other distributions is
3159 handled outside of the upload process.
3164 <heading><tt>Date</tt></heading>
3167 This field includes the date the package was built or last edited.
3171 The value of this field is usually extracted from the
3172 <file>debian/changelog</file> file - see
3173 <ref id="dpkgchangelog">).
3177 <sect1 id="f-Format">
3178 <heading><tt>Format</tt></heading>
3181 This field specifies a format revision for the file.
3182 The most current format described in the Policy Manual
3183 is version <strong>1.5</strong>. The syntax of the
3184 format value is the same as that of a package version
3185 number except that no epoch or Debian revision is allowed
3186 - see <ref id="f-Version">.
3190 <sect1 id="f-Urgency">
3191 <heading><tt>Urgency</tt></heading>
3194 This is a description of how important it is to upgrade to
3195 this version from previous ones. It consists of a single
3196 keyword taking one of the values <tt>low</tt>,
3197 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3198 <tt>critical</tt><footnote>
3199 Other urgency values are supported with configuration
3200 changes in the archive software but are not used in Debian.
3201 The urgency affects how quickly a package will be considered
3202 for inclusion into the <tt>testing</tt> distribution and
3203 gives an indication of the importance of any fixes included
3204 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3205 treated as synonymous.
3206 </footnote> (not case-sensitive) followed by an optional
3207 commentary (separated by a space) which is usually in
3208 parentheses. For example:
3211 Urgency: low (HIGH for users of diversions)
3217 The value of this field is usually extracted from the
3218 <file>debian/changelog</file> file - see
3219 <ref id="dpkgchangelog">.
3223 <sect1 id="f-Changes">
3224 <heading><tt>Changes</tt></heading>
3227 This field contains the human-readable changes data, describing
3228 the differences between the last version and the current one.
3232 There should be nothing in this field before the first
3233 newline; all the subsequent lines must be indented by at
3234 least one space; blank lines must be represented by a line
3235 consisting only of a space and a full stop.
3239 The value of this field is usually extracted from the
3240 <file>debian/changelog</file> file - see
3241 <ref id="dpkgchangelog">).
3245 Each version's change information should be preceded by a
3246 "title" line giving at least the version, distribution(s)
3247 and urgency, in a human-readable way.
3251 If data from several versions is being returned the entry
3252 for the most recent version should be returned first, and
3253 entries should be separated by the representation of a
3254 blank line (the "title" line may also be followed by the
3255 representation of blank line).
3259 <sect1 id="f-Binary">
3260 <heading><tt>Binary</tt></heading>
3263 This field is a list of binary packages. Its syntax and
3264 meaning varies depending on the control file in which it
3269 When it appears in the <file>.dsc</file> file, it lists binary
3270 packages which a source package can produce, separated by
3272 A space after each comma is conventional.
3273 </footnote>. It may span multiple lines. The source package
3274 does not necessarily produce all of these binary packages for
3275 every architecture. The source control file doesn't contain
3276 details of which architectures are appropriate for which of
3277 the binary packages.
3281 When it appears in a <file>.changes</file> file, it lists the
3282 names of the binary packages being uploaded, separated by
3283 whitespace (not commas). It may span multiple lines.
3287 <sect1 id="f-Installed-Size">
3288 <heading><tt>Installed-Size</tt></heading>
3291 This field appears in the control files of binary packages,
3292 and in the <file>Packages</file> files. It gives an estimate
3293 of the total amount of disk space required to install the
3294 named package. Actual installed size may vary based on block
3295 size, file system properties, or actions taken by package
3300 The disk space is given as the integer value of the estimated
3301 installed size in bytes, divided by 1024 and rounded up.
3305 <sect1 id="f-Files">
3306 <heading><tt>Files</tt></heading>
3309 This field contains a list of files with information about
3310 each one. The exact information and syntax varies with
3311 the context. In all cases the part of the field
3312 contents on the same line as the field name is empty. The
3313 remainder of the field is one line per file, each line
3314 being indented by one space and containing a number of
3315 sub-fields separated by spaces.
3319 In the <file>.dsc</file> file, each line contains the MD5
3320 checksum, size and filename of the tar file and (if applicable)
3321 diff file which make up the remainder of the source
3323 That is, the parts which are not the <tt>.dsc</tt>.
3325 The exact forms of the filenames are described
3326 in <ref id="pkg-sourcearchives">.
3330 In the <file>.changes</file> file this contains one line per
3331 file being uploaded. Each line contains the MD5 checksum,
3332 size, section and priority and the filename.
3333 The <qref id="f-Section">section</qref>
3334 and <qref id="f-Priority">priority</qref>
3335 are the values of the corresponding fields in
3336 the main source control file. If no section or priority is
3337 specified then <tt>-</tt> should be used, though section
3338 and priority values must be specified for new packages to
3339 be installed properly.
3343 The special value <tt>byhand</tt> for the section in a
3344 <tt>.changes</tt> file indicates that the file in question
3345 is not an ordinary package file and must by installed by
3346 hand by the distribution maintainers. If the section is
3347 <tt>byhand</tt> the priority should be <tt>-</tt>.
3351 If a new Debian revision of a package is being shipped and
3352 no new original source archive is being distributed the
3353 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3354 entry for the original source archive
3355 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3356 but the <file>.changes</file> file should leave it out. In
3357 this case the original source archive on the distribution
3358 site must match exactly, byte-for-byte, the original
3359 source archive which was used to generate the
3360 <file>.dsc</file> file and diff which are being uploaded.</p>
3363 <sect1 id="f-Closes">
3364 <heading><tt>Closes</tt></heading>
3367 A space-separated list of bug report numbers that the upload
3368 governed by the .changes file closes.
3372 <sect1 id="f-Homepage">
3373 <heading><tt>Homepage</tt></heading>
3376 The URL of the web site for this package, preferably (when
3377 applicable) the site from which the original source can be
3378 obtained and any additional upstream documentation or
3379 information may be found. The content of this field is a
3380 simple URL without any surrounding characters such as
3388 <heading>User-defined fields</heading>
3391 Additional user-defined fields may be added to the
3392 source package control file. Such fields will be
3393 ignored, and not copied to (for example) binary or
3394 source package control files or upload control files.
3398 If you wish to add additional unsupported fields to
3399 these output files you should use the mechanism
3404 Fields in the main source control information file with
3405 names starting <tt>X</tt>, followed by one or more of
3406 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3407 be copied to the output files. Only the part of the
3408 field name after the hyphen will be used in the output
3409 file. Where the letter <tt>B</tt> is used the field
3410 will appear in binary package control files, where the
3411 letter <tt>S</tt> is used in source package control
3412 files and where <tt>C</tt> is used in upload control
3413 (<tt>.changes</tt>) files.
3417 For example, if the main source information control file
3420 XBS-Comment: I stand between the candle and the star.
3422 then the binary and source package control files will contain the
3425 Comment: I stand between the candle and the star.
3434 <chapt id="maintainerscripts">
3435 <heading>Package maintainer scripts and installation procedure</heading>
3438 <heading>Introduction to package maintainer scripts</heading>
3441 It is possible to supply scripts as part of a package which
3442 the package management system will run for you when your
3443 package is installed, upgraded or removed.
3447 These scripts are the files <prgn>preinst</prgn>,
3448 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3449 <prgn>postrm</prgn> in the control area of the package.
3450 They must be proper executable files; if they are scripts
3451 (which is recommended), they must start with the usual
3452 <tt>#!</tt> convention. They should be readable and
3453 executable by anyone, and must not be world-writable.
3457 The package management system looks at the exit status from
3458 these scripts. It is important that they exit with a
3459 non-zero status if there is an error, so that the package
3460 management system can stop its processing. For shell
3461 scripts this means that you <em>almost always</em> need to
3462 use <tt>set -e</tt> (this is usually true when writing shell
3463 scripts, in fact). It is also important, of course, that
3464 they exit with a zero status if everything went well.
3468 Additionally, packages interacting with users using
3469 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3470 install a <prgn>config</prgn> script in the control area,
3471 see <ref id="maintscriptprompt"> for details.
3475 When a package is upgraded a combination of the scripts from
3476 the old and new packages is called during the upgrade
3477 procedure. If your scripts are going to be at all
3478 complicated you need to be aware of this, and may need to
3479 check the arguments to your scripts.
3483 Broadly speaking the <prgn>preinst</prgn> is called before
3484 (a particular version of) a package is installed, and the
3485 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3486 before (a version of) a package is removed and the
3487 <prgn>postrm</prgn> afterwards.
3491 Programs called from maintainer scripts should not normally
3492 have a path prepended to them. Before installation is
3493 started, the package management system checks to see if the
3494 programs <prgn>ldconfig</prgn>,
3495 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3496 and <prgn>update-rc.d</prgn> can be found via the
3497 <tt>PATH</tt> environment variable. Those programs, and any
3498 other program that one would expect to be in the
3499 <tt>PATH</tt>, should thus be invoked without an absolute
3500 pathname. Maintainer scripts should also not reset the
3501 <tt>PATH</tt>, though they might choose to modify it by
3502 prepending or appending package-specific directories. These
3503 considerations really apply to all shell scripts.</p>
3506 <sect id="idempotency">
3507 <heading>Maintainer scripts idempotency</heading>
3510 It is necessary for the error recovery procedures that the
3511 scripts be idempotent. This means that if it is run
3512 successfully, and then it is called again, it doesn't bomb
3513 out or cause any harm, but just ensures that everything is
3514 the way it ought to be. If the first call failed, or
3515 aborted half way through for some reason, the second call
3516 should merely do the things that were left undone the first
3517 time, if any, and exit with a success status if everything
3519 This is so that if an error occurs, the user interrupts
3520 <prgn>dpkg</prgn> or some other unforeseen circumstance
3521 happens you don't leave the user with a badly-broken
3522 package when <prgn>dpkg</prgn> attempts to repeat the
3528 <sect id="controllingterminal">
3529 <heading>Controlling terminal for maintainer scripts</heading>
3532 The maintainer scripts are guaranteed to run with a
3533 controlling terminal and can interact with the user.
3534 Because these scripts may be executed with standard output
3535 redirected into a pipe for logging purposes, Perl scripts
3536 should set unbuffered output by setting <tt>$|=1</tt> so
3537 that the output is printed immediately rather than being
3541 <sect id="exitstatus">
3542 <heading>Exit status</heading>
3545 Each script must return a zero exit status for
3546 success, or a nonzero one for failure, since the package
3547 management system looks for the exit status of these scripts
3548 and determines what action to take next based on that datum.
3552 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3557 <list compact="compact">
3559 <var>new-preinst</var> <tt>install</tt>
3562 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3565 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3568 <var>old-preinst</var> <tt>abort-upgrade</tt>
3569 <var>new-version</var>
3574 <list compact="compact">
3576 <var>postinst</var> <tt>configure</tt>
3577 <var>most-recently-configured-version</var>
3580 <var>old-postinst</var> <tt>abort-upgrade</tt>
3581 <var>new-version</var>
3584 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3585 <tt>in-favour</tt> <var>package</var>
3586 <var>new-version</var>
3589 <var>postinst</var> <tt>abort-remove</tt>
3592 <var>deconfigured's-postinst</var>
3593 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3594 <var>failed-install-package</var> <var>version</var>
3595 [<tt>removing</tt> <var>conflicting-package</var>
3601 <list compact="compact">
3603 <var>prerm</var> <tt>remove</tt>
3606 <var>old-prerm</var> <tt>upgrade</tt>
3607 <var>new-version</var>
3610 <var>new-prerm</var> <tt>failed-upgrade</tt>
3611 <var>old-version</var>
3614 <var>conflictor's-prerm</var> <tt>remove</tt>
3615 <tt>in-favour</tt> <var>package</var>
3616 <var>new-version</var>
3619 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3620 <tt>in-favour</tt> <var>package-being-installed</var>
3621 <var>version</var> [<tt>removing</tt>
3622 <var>conflicting-package</var>
3628 <list compact="compact">
3630 <var>postrm</var> <tt>remove</tt>
3633 <var>postrm</var> <tt>purge</tt>
3636 <var>old-postrm</var> <tt>upgrade</tt>
3637 <var>new-version</var>
3640 <var>new-postrm</var> <tt>failed-upgrade</tt>
3641 <var>old-version</var>
3644 <var>new-postrm</var> <tt>abort-install</tt>
3647 <var>new-postrm</var> <tt>abort-install</tt>
3648 <var>old-version</var>
3651 <var>new-postrm</var> <tt>abort-upgrade</tt>
3652 <var>old-version</var>
3655 <var>disappearer's-postrm</var> <tt>disappear</tt>
3656 <var>overwriter</var>
3657 <var>overwriter-version</var>
3663 <sect id="unpackphase">
3664 <heading>Details of unpack phase of installation or upgrade</heading>
3667 The procedure on installation/upgrade/overwrite/disappear
3668 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3669 stage of <tt>dpkg --install</tt>) is as follows. In each
3670 case, if a major error occurs (unless listed below) the
3671 actions are, in general, run backwards - this means that the
3672 maintainer scripts are run with different arguments in
3673 reverse order. These are the "error unwind" calls listed
3680 If a version of the package is already installed, call
3681 <example compact="compact">
3682 <var>old-prerm</var> upgrade <var>new-version</var>
3686 If the script runs but exits with a non-zero
3687 exit status, <prgn>dpkg</prgn> will attempt:
3688 <example compact="compact">
3689 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3691 If this works, the upgrade continues. If this
3692 does not work, the error unwind:
3693 <example compact="compact">
3694 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3696 If this works, then the old-version is
3697 "Installed", if not, the old version is in a
3698 "Failed-Config" state.
3704 If a "conflicting" package is being removed at the same time,
3705 or if any package will be broken (due to <tt>Breaks</tt>):
3708 If <tt>--auto-deconfigure</tt> is
3709 specified, call, for each package to be deconfigured
3710 due to <tt>Breaks</tt>:
3711 <example compact="compact">
3712 <var>deconfigured's-prerm</var> deconfigure \
3713 in-favour <var>package-being-installed</var> <var>version</var>
3716 <example compact="compact">
3717 <var>deconfigured's-postinst</var> abort-deconfigure \
3718 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3720 The deconfigured packages are marked as
3721 requiring configuration, so that if
3722 <tt>--install</tt> is used they will be
3723 configured again if possible.
3726 If any packages depended on a conflicting
3727 package being removed and <tt>--auto-deconfigure</tt> is
3728 specified, call, for each such package:
3729 <example compact="compact">
3730 <var>deconfigured's-prerm</var> deconfigure \
3731 in-favour <var>package-being-installed</var> <var>version</var> \
3732 removing <var>conflicting-package</var> <var>version</var>
3735 <example compact="compact">
3736 <var>deconfigured's-postinst</var> abort-deconfigure \
3737 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3738 removing <var>conflicting-package</var> <var>version</var>
3740 The deconfigured packages are marked as
3741 requiring configuration, so that if
3742 <tt>--install</tt> is used they will be
3743 configured again if possible.
3746 To prepare for removal of each conflicting package, call:
3747 <example compact="compact">
3748 <var>conflictor's-prerm</var> remove \
3749 in-favour <var>package</var> <var>new-version</var>
3752 <example compact="compact">
3753 <var>conflictor's-postinst</var> abort-remove \
3754 in-favour <var>package</var> <var>new-version</var>
3763 If the package is being upgraded, call:
3764 <example compact="compact">
3765 <var>new-preinst</var> upgrade <var>old-version</var>
3767 If this fails, we call:
3769 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3776 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3778 is called. If this works, then the old version
3779 is in an "Installed" state, or else it is left
3780 in an "Unpacked" state.
3785 If it fails, then the old version is left
3786 in an "Half-Installed" state.
3793 Otherwise, if the package had some configuration
3794 files from a previous version installed (i.e., it
3795 is in the "configuration files only" state):
3796 <example compact="compact">
3797 <var>new-preinst</var> install <var>old-version</var>
3801 <var>new-postrm</var> abort-install <var>old-version</var>
3803 If this fails, the package is left in a
3804 "Half-Installed" state, which requires a
3805 reinstall. If it works, the packages is left in
3806 a "Config Files" state.
3809 Otherwise (i.e., the package was completely purged):
3810 <example compact="compact">
3811 <var>new-preinst</var> install
3814 <example compact="compact">
3815 <var>new-postrm</var> abort-install
3817 If the error-unwind fails, the package is in a
3818 "Half Installed" phase, and requires a
3819 reinstall. If the error unwind works, the
3820 package is in a not installed state.
3827 The new package's files are unpacked, overwriting any
3828 that may be on the system already, for example any
3829 from the old version of the same package or from
3830 another package. Backups of the old files are kept
3831 temporarily, and if anything goes wrong the package
3832 management system will attempt to put them back as
3833 part of the error unwind.
3837 It is an error for a package to contain files which
3838 are on the system in another package, unless
3839 <tt>Replaces</tt> is used (see <ref id="replaces">).
3841 The following paragraph is not currently the case:
3842 Currently the <tt>- - force-overwrite</tt> flag is
3843 enabled, downgrading it to a warning, but this may not
3849 It is a more serious error for a package to contain a
3850 plain file or other kind of non-directory where another
3851 package has a directory (again, unless
3852 <tt>Replaces</tt> is used). This error can be
3853 overridden if desired using
3854 <tt>--force-overwrite-dir</tt>, but this is not
3859 Packages which overwrite each other's files produce
3860 behavior which, though deterministic, is hard for the
3861 system administrator to understand. It can easily
3862 lead to "missing" programs if, for example, a package
3863 is installed which overwrites a file from another
3864 package, and is then removed again.<footnote>
3865 Part of the problem is due to what is arguably a
3866 bug in <prgn>dpkg</prgn>.
3871 A directory will never be replaced by a symbolic link
3872 to a directory or vice versa; instead, the existing
3873 state (symlink or not) will be left alone and
3874 <prgn>dpkg</prgn> will follow the symlink if there is
3883 If the package is being upgraded, call
3884 <example compact="compact">
3885 <var>old-postrm</var> upgrade <var>new-version</var>
3889 If this fails, <prgn>dpkg</prgn> will attempt:
3890 <example compact="compact">
3891 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3893 If this works, installation continues. If not,
3895 <example compact="compact">
3896 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3898 If this fails, the old version is left in an
3899 "Half Installed" state. If it works, dpkg now
3901 <example compact="compact">
3902 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3904 If this fails, the old version is left in an
3905 "Half Installed" state. If it works, dpkg now
3907 <example compact="compact">
3908 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3910 If this fails, the old version is in an
3917 This is the point of no return - if
3918 <prgn>dpkg</prgn> gets this far, it won't back off
3919 past this point if an error occurs. This will
3920 leave the package in a fairly bad state, which
3921 will require a successful re-installation to clear
3922 up, but it's when <prgn>dpkg</prgn> starts doing
3923 things that are irreversible.
3928 Any files which were in the old version of the package
3929 but not in the new are removed.
3933 The new file list replaces the old.
3937 The new maintainer scripts replace the old.
3941 Any packages all of whose files have been overwritten
3942 during the installation, and which aren't required for
3943 dependencies, are considered to have been removed.
3944 For each such package
3947 <prgn>dpkg</prgn> calls:
3948 <example compact="compact">
3949 <var>disappearer's-postrm</var> disappear \
3950 <var>overwriter</var> <var>overwriter-version</var>
3954 The package's maintainer scripts are removed.
3957 It is noted in the status database as being in a
3958 sane state, namely not installed (any conffiles
3959 it may have are ignored, rather than being
3960 removed by <prgn>dpkg</prgn>). Note that
3961 disappearing packages do not have their prerm
3962 called, because <prgn>dpkg</prgn> doesn't know
3963 in advance that the package is going to
3970 Any files in the package we're unpacking that are also
3971 listed in the file lists of other packages are removed
3972 from those lists. (This will lobotomize the file list
3973 of the "conflicting" package if there is one.)
3977 The backup files made during installation, above, are
3983 The new package's status is now sane, and recorded as
3988 Here is another point of no return - if the
3989 conflicting package's removal fails we do not unwind
3990 the rest of the installation; the conflicting package
3991 is left in a half-removed limbo.
3996 If there was a conflicting package we go and do the
3997 removal actions (described below), starting with the
3998 removal of the conflicting package's files (any that
3999 are also in the package being installed have already
4000 been removed from the conflicting package's file list,
4001 and so do not get removed now).
4007 <sect id="configdetails"><heading>Details of configuration</heading>
4010 When we configure a package (this happens with <tt>dpkg
4011 --install</tt> and <tt>dpkg --configure</tt>), we first
4012 update any <tt>conffile</tt>s and then call:
4013 <example compact="compact">
4014 <var>postinst</var> configure <var>most-recently-configured-version</var>
4019 No attempt is made to unwind after errors during
4020 configuration. If the configuration fails, the package is in
4021 a "Failed Config" state, and an error message is generated.
4025 If there is no most recently configured version
4026 <prgn>dpkg</prgn> will pass a null argument.
4029 Historical note: Truly ancient (pre-1997) versions of
4030 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4031 (including the angle brackets) in this case. Even older
4032 ones did not pass a second argument at all, under any
4033 circumstance. Note that upgrades using such an old dpkg
4034 version are unlikely to work for other reasons, even if
4035 this old argument behavior is handled by your postinst script.
4041 <sect id="removedetails"><heading>Details of removal and/or
4042 configuration purging</heading>
4048 <example compact="compact">
4049 <var>prerm</var> remove
4053 If prerm fails during replacement due to conflict
4055 <var>conflictor's-postinst</var> abort-remove \
4056 in-favour <var>package</var> <var>new-version</var>
4060 <var>postinst</var> abort-remove
4064 If this fails, the package is in a "Failed-Config"
4065 state, or else it remains "Installed".
4069 The package's files are removed (except <tt>conffile</tt>s).
4072 <example compact="compact">
4073 <var>postrm</var> remove
4077 If it fails, there's no error unwind, and the package is in
4078 an "Half-Installed" state.
4083 All the maintainer scripts except the <prgn>postrm</prgn>
4088 If we aren't purging the package we stop here. Note
4089 that packages which have no <prgn>postrm</prgn> and no
4090 <tt>conffile</tt>s are automatically purged when
4091 removed, as there is no difference except for the
4092 <prgn>dpkg</prgn> status.
4096 The <tt>conffile</tt>s and any backup files
4097 (<tt>~</tt>-files, <tt>#*#</tt> files,
4098 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4103 <example compact="compact">
4104 <var>postrm</var> purge
4108 If this fails, the package remains in a "Config-Files"
4113 The package's file list is removed.
4122 <chapt id="relationships">
4123 <heading>Declaring relationships between packages</heading>
4125 <sect id="depsyntax">
4126 <heading>Syntax of relationship fields</heading>
4129 These fields all have a uniform syntax. They are a list of
4130 package names separated by commas.
4134 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4135 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4136 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4137 control file fields of the package, which declare
4138 dependencies on other packages, the package names listed may
4139 also include lists of alternative package names, separated
4140 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4141 if any one of the alternative packages is installed, that
4142 part of the dependency is considered to be satisfied.
4146 All of the fields except for <tt>Provides</tt> may restrict
4147 their applicability to particular versions of each named
4148 package. This is done in parentheses after each individual
4149 package name; the parentheses should contain a relation from
4150 the list below followed by a version number, in the format
4151 described in <ref id="f-Version">.
4155 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4156 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4157 strictly earlier, earlier or equal, exactly equal, later or
4158 equal and strictly later, respectively. The deprecated
4159 forms <tt><</tt> and <tt>></tt> were used to mean
4160 earlier/later or equal, rather than strictly earlier/later,
4161 so they should not appear in new packages (though
4162 <prgn>dpkg</prgn> still supports them).
4166 Whitespace may appear at any point in the version
4167 specification subject to the rules in <ref
4168 id="controlsyntax">, and must appear where it's necessary to
4169 disambiguate; it is not otherwise significant. All of the
4170 relationship fields may span multiple lines. For
4171 consistency and in case of future changes to
4172 <prgn>dpkg</prgn> it is recommended that a single space be
4173 used after a version relationship and before a version
4174 number; it is also conventional to put a single space after
4175 each comma, on either side of each vertical bar, and before
4176 each open parenthesis. When wrapping a relationship field, it
4177 is conventional to do so after a comma and before the space
4178 following that comma.
4182 For example, a list of dependencies might appear as:
4183 <example compact="compact">
4186 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4191 All fields that specify build-time relationships
4192 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4193 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4194 may be restricted to a certain set of architectures. This
4195 is indicated in brackets after each individual package name and
4196 the optional version specification. The brackets enclose a
4197 list of Debian architecture names separated by whitespace.
4198 Exclamation marks may be prepended to each of the names.
4199 (It is not permitted for some names to be prepended with
4200 exclamation marks while others aren't.) If the current Debian
4201 host architecture is not in this list and there are no
4202 exclamation marks in the list, or it is in the list with a
4203 prepended exclamation mark, the package name and the
4204 associated version specification are ignored completely for
4205 the purposes of defining the relationships.
4210 <example compact="compact">
4212 Build-Depends-Indep: texinfo
4213 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4214 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4216 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4217 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4218 <tt>gnumach-dev</tt> only on hurd-i386.
4222 If the architecture-restricted dependency is part of a set of
4223 alternatives using <tt>|</tt>, that alternative is ignored
4224 completely on architectures that do not match the restriction.
4226 <example compact="compact">
4227 Build-Depends: foo [!i386] | bar [!amd64]
4229 is equivalent to <tt>bar</tt> on the i386 architecture, to
4230 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4231 bar</tt> on all other architectures.
4235 Note that the binary package relationship fields such as
4236 <tt>Depends</tt> appear in one of the binary package
4237 sections of the control file, whereas the build-time
4238 relationships such as <tt>Build-Depends</tt> appear in the
4239 source package section of the control file (which is the
4244 <sect id="binarydeps">
4245 <heading>Binary Dependencies - <tt>Depends</tt>,
4246 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4247 <tt>Pre-Depends</tt>
4251 Packages can declare in their control file that they have
4252 certain relationships to other packages - for example, that
4253 they may not be installed at the same time as certain other
4254 packages, and/or that they depend on the presence of others.
4258 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4259 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4260 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4261 <tt>Breaks</tt> is described in <ref id="breaks">, and
4262 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4263 rest are described below.
4267 These seven fields are used to declare a dependency
4268 relationship by one package on another. Except for
4269 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4270 depending (binary) package's control file.
4271 (<tt>Enhances</tt> appears in the recommending package's
4272 control file, and <tt>Breaks</tt> appears in the version of
4273 depended-on package which causes the named package to
4278 A <tt>Depends</tt> field takes effect <em>only</em> when a
4279 package is to be configured. It does not prevent a package
4280 being on the system in an unconfigured state while its
4281 dependencies are unsatisfied, and it is possible to replace
4282 a package whose dependencies are satisfied and which is
4283 properly installed with a different version whose
4284 dependencies are not and cannot be satisfied; when this is
4285 done the depending package will be left unconfigured (since
4286 attempts to configure it will give errors) and will not
4287 function properly. If it is necessary, a
4288 <tt>Pre-Depends</tt> field can be used, which has a partial
4289 effect even when a package is being unpacked, as explained
4290 in detail below. (The other three dependency fields,
4291 <tt>Recommends</tt>, <tt>Suggests</tt> and
4292 <tt>Enhances</tt>, are only used by the various front-ends
4293 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4294 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4298 For this reason packages in an installation run are usually
4299 all unpacked first and all configured later; this gives
4300 later versions of packages with dependencies on later
4301 versions of other packages the opportunity to have their
4302 dependencies satisfied.
4306 In case of circular dependencies, since installation or
4307 removal order honoring the dependency order can't be
4308 established, dependency loops are broken at some point
4309 (based on rules below), and some packages may not be able to
4310 rely on their dependencies being present when being
4311 installed or removed, depending on which side of the break
4312 of the circular dependency loop they happen to be on. If one
4313 of the packages in the loop has no postinst script, then the
4314 cycle will be broken at that package, so as to ensure that
4315 all postinst scripts run with the dependencies properly
4316 configured if this is possible. Otherwise the breaking point
4321 The <tt>Depends</tt> field thus allows package maintainers
4322 to impose an order in which packages should be configured.
4326 The meaning of the five dependency fields is as follows:
4328 <tag><tt>Depends</tt></tag>
4331 This declares an absolute dependency. A package will
4332 not be configured unless all of the packages listed in
4333 its <tt>Depends</tt> field have been correctly
4338 The <tt>Depends</tt> field should be used if the
4339 depended-on package is required for the depending
4340 package to provide a significant amount of
4345 The <tt>Depends</tt> field should also be used if the
4346 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4347 <prgn>postrm</prgn> scripts require the package to be
4348 present in order to run. Note, however, that the
4349 <prgn>postrm</prgn> cannot rely on any non-essential
4350 packages to be present during the <tt>purge</tt>
4354 <tag><tt>Recommends</tt></tag>
4357 This declares a strong, but not absolute, dependency.
4361 The <tt>Recommends</tt> field should list packages
4362 that would be found together with this one in all but
4363 unusual installations.
4367 <tag><tt>Suggests</tt></tag>
4369 This is used to declare that one package may be more
4370 useful with one or more others. Using this field
4371 tells the packaging system and the user that the
4372 listed packages are related to this one and can
4373 perhaps enhance its usefulness, but that installing
4374 this one without them is perfectly reasonable.
4377 <tag><tt>Enhances</tt></tag>
4379 This field is similar to Suggests but works in the
4380 opposite direction. It is used to declare that a
4381 package can enhance the functionality of another
4385 <tag><tt>Pre-Depends</tt></tag>
4388 This field is like <tt>Depends</tt>, except that it
4389 also forces <prgn>dpkg</prgn> to complete installation
4390 of the packages named before even starting the
4391 installation of the package which declares the
4392 pre-dependency, as follows:
4396 When a package declaring a pre-dependency is about to
4397 be <em>unpacked</em> the pre-dependency can be
4398 satisfied if the depended-on package is either fully
4399 configured, <em>or even if</em> the depended-on
4400 package(s) are only unpacked or half-configured,
4401 provided that they have been configured correctly at
4402 some point in the past (and not removed or partially
4403 removed since). In this case, both the
4404 previously-configured and currently unpacked or
4405 half-configured versions must satisfy any version
4406 clause in the <tt>Pre-Depends</tt> field.
4410 When the package declaring a pre-dependency is about
4411 to be <em>configured</em>, the pre-dependency will be
4412 treated as a normal <tt>Depends</tt>, that is, it will
4413 be considered satisfied only if the depended-on
4414 package has been correctly configured.
4418 <tt>Pre-Depends</tt> should be used sparingly,
4419 preferably only by packages whose premature upgrade or
4420 installation would hamper the ability of the system to
4421 continue with any upgrade that might be in progress.
4425 <tt>Pre-Depends</tt> are also required if the
4426 <prgn>preinst</prgn> script depends on the named
4427 package. It is best to avoid this situation if
4435 When selecting which level of dependency to use you should
4436 consider how important the depended-on package is to the
4437 functionality of the one declaring the dependency. Some
4438 packages are composed of components of varying degrees of
4439 importance. Such a package should list using
4440 <tt>Depends</tt> the package(s) which are required by the
4441 more important components. The other components'
4442 requirements may be mentioned as Suggestions or
4443 Recommendations, as appropriate to the components' relative
4449 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4452 When one binary package declares that it breaks another,
4453 <prgn>dpkg</prgn> will refuse to allow the package which
4454 declares <tt>Breaks</tt> be installed unless the broken
4455 package is deconfigured first, and it will refuse to
4456 allow the broken package to be reconfigured.
4460 A package will not be regarded as causing breakage merely
4461 because its configuration files are still installed; it must
4462 be at least half-installed.
4466 A special exception is made for packages which declare that
4467 they break their own package name or a virtual package which
4468 they provide (see below): this does not count as a real
4473 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4474 version clause; such a <tt>Breaks</tt> is introduced in the
4475 version of an (implicit or explicit) dependency which
4476 violates an assumption or reveals a bug in earlier versions
4477 of the broken package. This use of <tt>Breaks</tt> will
4478 inform higher-level package management tools that broken
4479 package must be upgraded before the new one.
4483 If the breaking package also overwrites some files from the
4484 older package, it should use <tt>Replaces</tt> (not
4485 <tt>Conflicts</tt>) to ensure this goes smoothly.
4489 <sect id="conflicts">
4490 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4493 When one binary package declares a conflict with another
4494 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4495 refuse to allow them to be installed on the system at the
4500 If one package is to be installed, the other must be removed
4501 first - if the package being installed is marked as
4502 replacing (see <ref id="replaces">) the one on the system,
4503 or the one on the system is marked as deselected, or both
4504 packages are marked <tt>Essential</tt>, then
4505 <prgn>dpkg</prgn> will automatically remove the package
4506 which is causing the conflict, otherwise it will halt the
4507 installation of the new package with an error. This
4508 mechanism is specifically designed to produce an error when
4509 the installed package is <tt>Essential</tt>, but the new
4514 A package will not cause a conflict merely because its
4515 configuration files are still installed; it must be at least
4520 A special exception is made for packages which declare a
4521 conflict with their own package name, or with a virtual
4522 package which they provide (see below): this does not
4523 prevent their installation, and allows a package to conflict
4524 with others providing a replacement for it. You use this
4525 feature when you want the package in question to be the only
4526 package providing some feature.
4530 A <tt>Conflicts</tt> entry should almost never have an
4531 "earlier than" version clause. This would prevent
4532 <prgn>dpkg</prgn> from upgrading or installing the package
4533 which declared such a conflict until the upgrade or removal
4534 of the conflicted-with package had been completed. Instead,
4535 <tt>Breaks</tt> may be used.
4539 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4543 As well as the names of actual ("concrete") packages, the
4544 package relationship fields <tt>Depends</tt>,
4545 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4546 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4547 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4548 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4549 may mention "virtual packages".
4553 A <em>virtual package</em> is one which appears in the
4554 <tt>Provides</tt> control file field of another package.
4555 The effect is as if the package(s) which provide a
4556 particular virtual package name had been listed by name
4557 everywhere the virtual package name appears. (See also <ref
4562 If there are both concrete and virtual packages of the same
4563 name, then the dependency may be satisfied (or the conflict
4564 caused) by either the concrete package with the name in
4565 question or any other concrete package which provides the
4566 virtual package with the name in question. This is so that,
4567 for example, supposing we have
4568 <example compact="compact">
4571 </example> and someone else releases an enhanced version of
4572 the <tt>bar</tt> package they can say:
4573 <example compact="compact">
4577 and the <tt>bar-plus</tt> package will now also satisfy the
4578 dependency for the <tt>foo</tt> package.
4582 If a relationship field has a version number attached
4583 then only real packages will be considered to see whether
4584 the relationship is satisfied (or the prohibition violated,
4585 for a conflict or breakage) - it is assumed that a real
4586 package which provides the virtual package is not of the
4587 "right" version. So, a <tt>Provides</tt> field may not
4588 contain version numbers, and the version number of the
4589 concrete package which provides a particular virtual package
4590 will not be looked at when considering a dependency on or
4591 conflict with the virtual package name.
4595 It is likely that the ability will be added in a future
4596 release of <prgn>dpkg</prgn> to specify a version number for
4597 each virtual package it provides. This feature is not yet
4598 present, however, and is expected to be used only
4603 If you want to specify which of a set of real packages
4604 should be the default to satisfy a particular dependency on
4605 a virtual package, you should list the real package as an
4606 alternative before the virtual one.
4611 <sect id="replaces"><heading>Overwriting files and replacing
4612 packages - <tt>Replaces</tt></heading>
4615 Packages can declare in their control file that they should
4616 overwrite files in certain other packages, or completely
4617 replace other packages. The <tt>Replaces</tt> control file
4618 field has these two distinct purposes.
4621 <sect1><heading>Overwriting files in other packages</heading>
4624 Firstly, as mentioned before, it is usually an error for a
4625 package to contain files which are on the system in
4630 However, if the overwriting package declares that it
4631 <tt>Replaces</tt> the one containing the file being
4632 overwritten, then <prgn>dpkg</prgn> will replace the file
4633 from the old package with that from the new. The file
4634 will no longer be listed as "owned" by the old package.
4638 If a package is completely replaced in this way, so that
4639 <prgn>dpkg</prgn> does not know of any files it still
4640 contains, it is considered to have "disappeared". It will
4641 be marked as not wanted on the system (selected for
4642 removal) and not installed. Any <tt>conffile</tt>s
4643 details noted for the package will be ignored, as they
4644 will have been taken over by the overwriting package. The
4645 package's <prgn>postrm</prgn> script will be run with a
4646 special argument to allow the package to do any final
4647 cleanup required. See <ref id="mscriptsinstact">.
4650 Replaces is a one way relationship -- you have to
4651 install the replacing package after the replaced
4658 For this usage of <tt>Replaces</tt>, virtual packages (see
4659 <ref id="virtual">) are not considered when looking at a
4660 <tt>Replaces</tt> field - the packages declared as being
4661 replaced must be mentioned by their real names.
4665 Furthermore, this usage of <tt>Replaces</tt> only takes
4666 effect when both packages are at least partially on the
4667 system at once, so that it can only happen if they do not
4668 conflict or if the conflict has been overridden.
4673 <sect1><heading>Replacing whole packages, forcing their
4677 Secondly, <tt>Replaces</tt> allows the packaging system to
4678 resolve which package should be removed when there is a
4679 conflict - see <ref id="conflicts">. This usage only
4680 takes effect when the two packages <em>do</em> conflict,
4681 so that the two usages of this field do not interfere with
4686 In this situation, the package declared as being replaced
4687 can be a virtual package, so for example, all mail
4688 transport agents (MTAs) would have the following fields in
4689 their control files:
4690 <example compact="compact">
4691 Provides: mail-transport-agent
4692 Conflicts: mail-transport-agent
4693 Replaces: mail-transport-agent
4695 ensuring that only one MTA can be installed at any one
4700 <sect id="sourcebinarydeps">
4701 <heading>Relationships between source and binary packages -
4702 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4703 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4707 Source packages that require certain binary packages to be
4708 installed or absent at the time of building the package
4709 can declare relationships to those binary packages.
4713 This is done using the <tt>Build-Depends</tt>,
4714 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4715 <tt>Build-Conflicts-Indep</tt> control file fields.
4719 Build-dependencies on "build-essential" binary packages can be
4720 omitted. Please see <ref id="pkg-relations"> for more information.
4724 The dependencies and conflicts they define must be satisfied
4725 (as defined earlier for binary packages) in order to invoke
4726 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4728 If you make "build-arch" or "binary-arch", you need
4729 Build-Depends. If you make "build-indep" or
4730 "binary-indep", you need Build-Depends and
4731 Build-Depends-Indep. If you make "build" or "binary",
4735 There is no Build-Depends-Arch; this role is essentially
4736 met with Build-Depends. Anyone building the
4737 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4738 is basically assumed to be building the whole package
4739 anyway and so installs all build dependencies. The
4740 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4741 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4742 does not yet know how to check for its existence) and
4743 <tt>binary-arch</tt>.
4746 The purpose of the original split, I recall, was so that
4747 the autobuilders wouldn't need to install extra packages
4748 needed only for the binary-indep targets. But without a
4749 build-arch/build-indep split, this didn't work, since
4750 most of the work is done in the build target, not in the
4756 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4758 The <tt>Build-Depends</tt> and
4759 <tt>Build-Conflicts</tt> fields must be satisfied when
4760 any of the following targets is invoked:
4761 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4762 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4763 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4765 <tag><tt>Build-Depends-Indep</tt>,
4766 <tt>Build-Conflicts-Indep</tt></tag>
4768 The <tt>Build-Depends-Indep</tt> and
4769 <tt>Build-Conflicts-Indep</tt> fields must be
4770 satisfied when any of the following targets is
4771 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4772 <tt>binary</tt> and <tt>binary-indep</tt>.
4782 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4785 Packages containing shared libraries must be constructed with
4786 a little care to make sure that the shared library is always
4787 available. This is especially important for packages whose
4788 shared libraries are vitally important, such as the C library
4789 (currently <tt>libc6</tt>).
4793 Packages involving shared libraries should be split up into
4794 several binary packages. This section mostly deals with how
4795 this separation is to be accomplished; rules for files within
4796 the shared library packages are in <ref id="libraries"> instead.
4799 <sect id="sharedlibs-runtime">
4800 <heading>Run-time shared libraries</heading>
4803 The run-time shared library needs to be placed in a package
4804 whose name changes whenever the shared object version
4807 Since it is common place to install several versions of a
4808 package that just provides shared libraries, it is a
4809 good idea that the library package should not
4810 contain any extraneous non-versioned files, unless they
4811 happen to be in versioned directories.</p>
4813 The most common mechanism is to place it in a package
4815 <package><var>libraryname</var><var>soversion</var></package>,
4816 where <file><var>soversion</var></file> is the version number
4817 in the soname of the shared library<footnote>
4818 The soname is the shared object name: it's the thing
4819 that has to match exactly between building an executable
4820 and running it for the dynamic linker to be able run the
4821 program. For example, if the soname of the library is
4822 <file>libfoo.so.6</file>, the library package would be
4823 called <file>libfoo6</file>.
4825 Alternatively, if it would be confusing to directly append
4826 <var>soversion</var> to <var>libraryname</var> (e.g. because
4827 <var>libraryname</var> itself ends in a number), you may use
4828 <package><var>libraryname</var>-<var>soversion</var></package> and
4829 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4834 If you have several shared libraries built from the same
4835 source tree you may lump them all together into a single
4836 shared library package, provided that you change all of
4837 their sonames at once (so that you don't get filename
4838 clashes if you try to install different versions of the
4839 combined shared libraries package).
4843 The package should install the shared libraries under
4844 their normal names. For example, the <package>libgdbm3</package>
4845 package should install <file>libgdbm.so.3.0.0</file> as
4846 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4847 renamed or re-linked by any <prgn>prerm</prgn> or
4848 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4849 of renaming things safely without affecting running programs,
4850 and attempts to interfere with this are likely to lead to
4855 Shared libraries should not be installed executable, since
4856 the dynamic linker does not require this and trying to
4857 execute a shared library usually results in a core dump.
4861 The run-time library package should include the symbolic link that
4862 <prgn>ldconfig</prgn> would create for the shared libraries.
4863 For example, the <package>libgdbm3</package> package should include
4864 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4865 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4866 linker (for example <prgn>ld.so</prgn> or
4867 <prgn>ld-linux.so.*</prgn>) can find the library between the
4868 time that <prgn>dpkg</prgn> installs it and the time that
4869 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4871 The package management system requires the library to be
4872 placed before the symbolic link pointing to it in the
4873 <file>.deb</file> file. This is so that when
4874 <prgn>dpkg</prgn> comes to install the symlink
4875 (overwriting the previous symlink pointing at an older
4876 version of the library), the new shared library is already
4877 in place. In the past, this was achieved by creating the
4878 library in the temporary packaging directory before
4879 creating the symlink. Unfortunately, this was not always
4880 effective, since the building of the tar file in the
4881 <file>.deb</file> depended on the behavior of the underlying
4882 file system. Some file systems (such as reiserfs) reorder
4883 the files so that the order of creation is forgotten.
4884 Since version 1.7.0, <prgn>dpkg</prgn>
4885 reorders the files itself as necessary when building a
4886 package. Thus it is no longer important to concern
4887 oneself with the order of file creation.
4891 <sect1 id="ldconfig">
4892 <heading><tt>ldconfig</tt></heading>
4895 Any package installing shared libraries in one of the default
4896 library directories of the dynamic linker (which are currently
4897 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4898 listed in <file>/etc/ld.so.conf</file><footnote>
4900 <list compact="compact">
4901 <item>/usr/local/lib</item>
4902 <item>/usr/lib/libc5-compat</item>
4903 <item>/lib/libc5-compat</item>
4906 must use <prgn>ldconfig</prgn> to update the shared library
4911 The package maintainer scripts must only call
4912 <prgn>ldconfig</prgn> under these circumstances:
4913 <list compact="compact">
4914 <item>When the <prgn>postinst</prgn> script is run with a
4915 first argument of <tt>configure</tt>, the script must call
4916 <prgn>ldconfig</prgn>, and may optionally invoke
4917 <prgn>ldconfig</prgn> at other times.
4919 <item>When the <prgn>postrm</prgn> script is run with a
4920 first argument of <tt>remove</tt>, the script should call
4921 <prgn>ldconfig</prgn>.
4926 During install or upgrade, the preinst is called before
4927 the new files are installed, so calling "ldconfig" is
4928 pointless. The preinst of an existing package can also be
4929 called if an upgrade fails. However, this happens during
4930 the critical time when a shared libs may exist on-disk
4931 under a temporary name. Thus, it is dangerous and
4932 forbidden by current policy to call "ldconfig" at this
4937 When a package is installed or upgraded, "postinst
4938 configure" runs after the new files are safely on-disk.
4939 Since it is perfectly safe to invoke ldconfig
4940 unconditionally in a postinst, it is OK for a package to
4941 simply put ldconfig in its postinst without checking the
4942 argument. The postinst can also be called to recover from
4943 a failed upgrade. This happens before any new files are
4944 unpacked, so there is no reason to call "ldconfig" at this
4949 For a package that is being removed, prerm is
4950 called with all the files intact, so calling ldconfig is
4951 useless. The other calls to "prerm" happen in the case of
4952 upgrade at a time when all the files of the old package
4953 are on-disk, so again calling "ldconfig" is pointless.
4957 postrm, on the other hand, is called with the "remove"
4958 argument just after the files are removed, so this is
4959 the proper time to call "ldconfig" to notify the system
4960 of the fact that the shared libraries from the package
4961 are removed. The postrm can be called at several other
4962 times. At the time of "postrm purge", "postrm
4963 abort-install", or "postrm abort-upgrade", calling
4964 "ldconfig" is useless because the shared lib files are
4965 not on-disk. However, when "postrm" is invoked with
4966 arguments "upgrade", "failed-upgrade", or "disappear", a
4967 shared lib may exist on-disk under a temporary filename.
4975 <sect id="sharedlibs-support-files">
4976 <heading>Shared library support files</heading>
4979 If your package contains files whose names do not change with
4980 each change in the library shared object version, you must not
4981 put them in the shared library package. Otherwise, several
4982 versions of the shared library cannot be installed at the same
4983 time without filename clashes, making upgrades and transitions
4984 unnecessarily difficult.
4988 It is recommended that supporting files and run-time support
4989 programs that do not need to be invoked manually by users, but
4990 are nevertheless required for the package to function, be placed
4991 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
4992 preferably under <file>/usr/lib/</file><var>package-name</var>.
4993 If the program or file is architecture independent, the
4994 recommendation is for it to be placed in a subdirectory of
4995 <file>/usr/share</file> instead, preferably under
4996 <file>/usr/share/</file><var>package-name</var>. Following the
4997 <var>package-name</var> naming convention ensures that the file
4998 names change when the shared object version changes.
5002 Run-time support programs that use the shared library but are
5003 not required for the library to function or files used by the
5004 shared library that can be used by any version of the shared
5005 library package should instead be put in a separate package.
5006 This package might typically be named
5007 <package><var>libraryname</var>-tools</package>; note the
5008 absence of the <var>soversion</var> in the package name.
5012 Files and support programs only useful when compiling software
5013 against the library should be included in the development
5014 package for the library.<footnote>
5015 For example, a <file><var>package-name</var>-config</file>
5016 script or <package>pkg-config</package> configuration files.
5021 <sect id="sharedlibs-static">
5022 <heading>Static libraries</heading>
5025 The static library (<file><var>libraryname.a</var></file>)
5026 is usually provided in addition to the shared version.
5027 It is placed into the development package (see below).
5031 In some cases, it is acceptable for a library to be
5032 available in static form only; these cases include:
5034 <item>libraries for languages whose shared library support
5035 is immature or unstable</item>
5036 <item>libraries whose interfaces are in flux or under
5037 development (commonly the case when the library's
5038 major version number is zero, or where the ABI breaks
5039 across patchlevels)</item>
5040 <item>libraries which are explicitly intended to be
5041 available only in static form by their upstream
5046 <sect id="sharedlibs-dev">
5047 <heading>Development files</heading>
5050 The development files associated to a shared library need to be
5051 placed in a package called
5052 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5053 or if you prefer only to support one development version at a
5054 time, <package><var>libraryname</var>-dev</package>.
5058 In case several development versions of a library exist, you may
5059 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5060 <ref id="conflicts">) to ensure that the user only installs one
5061 development version at a time (as different development versions are
5062 likely to have the same header files in them, which would cause a
5063 filename clash if both were installed).
5067 The development package should contain a symlink for the associated
5068 shared library without a version number. For example, the
5069 <package>libgdbm-dev</package> package should include a symlink
5070 from <file>/usr/lib/libgdbm.so</file> to
5071 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5072 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5073 <file>libgdbm.so</file> when compiling dynamically.
5077 <sect id="sharedlibs-intradeps">
5078 <heading>Dependencies between the packages of the same library</heading>
5081 Typically the development version should have an exact
5082 version dependency on the runtime library, to make sure that
5083 compilation and linking happens correctly. The
5084 <tt>${binary:Version}</tt> substitution variable can be
5085 useful for this purpose.
5087 Previously, <tt>${Source-Version}</tt> was used, but its name
5088 was confusing and it has been deprecated since dpkg 1.13.19.
5093 <sect id="sharedlibs-shlibdeps">
5094 <heading>Dependencies between the library and other packages -
5095 the <tt>shlibs</tt> system</heading>
5098 If a package contains a binary or library which links to a
5099 shared library, we must ensure that when the package is
5100 installed on the system, all of the libraries needed are
5101 also installed. This requirement led to the creation of the
5102 <tt>shlibs</tt> system, which is very simple in its design:
5103 any package which <em>provides</em> a shared library also
5104 provides information on the package dependencies required to
5105 ensure the presence of this library, and any package which
5106 <em>uses</em> a shared library uses this information to
5107 determine the dependencies it requires. The files which
5108 contain the mapping from shared libraries to the necessary
5109 dependency information are called <file>shlibs</file> files.
5113 Thus, when a package is built which contains any shared
5114 libraries, it must provide a <file>shlibs</file> file for other
5115 packages to use, and when a package is built which contains
5116 any shared libraries or compiled binaries, it must run
5117 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5118 on these to determine the libraries used and hence the
5119 dependencies needed by this package.<footnote>
5121 In the past, the shared libraries linked to were
5122 determined by calling <prgn>ldd</prgn>, but now
5123 <prgn>objdump</prgn> is used to do this. The only
5124 change this makes to package building is that
5125 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5126 libraries, whereas in the past this was unnecessary.
5127 The rest of this footnote explains the advantage that
5132 We say that a binary <tt>foo</tt> <em>directly</em> uses
5133 a library <tt>libbar</tt> if it is explicitly linked
5134 with that library (that is, it uses the flag
5135 <tt>-lbar</tt> during the linking stage). Other
5136 libraries that are needed by <tt>libbar</tt> are linked
5137 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5138 linker will load them automatically when it loads
5139 <tt>libbar</tt>. A package should depend on
5140 the libraries it directly uses, and the dependencies for
5141 those libraries should automatically pull in the other
5146 Unfortunately, the <prgn>ldd</prgn> program shows both
5147 the directly and indirectly used libraries, meaning that
5148 the dependencies determined included both direct and
5149 indirect dependencies. The use of <prgn>objdump</prgn>
5150 avoids this problem by determining only the directly
5155 A good example of where this helps is the following. We
5156 could update <tt>libimlib</tt> with a new version that
5157 supports a new graphics format called dgf (but retaining
5158 the same major version number). If we used the old
5159 <prgn>ldd</prgn> method, every package that uses
5160 <tt>libimlib</tt> would need to be recompiled so it
5161 would also depend on <tt>libdgf</tt> or it wouldn't run
5162 due to missing symbols. However with the new system,
5163 packages using <tt>libimlib</tt> can rely on
5164 <tt>libimlib</tt> itself having the dependency on
5165 <tt>libdgf</tt> and so they would not need rebuilding.
5171 In the following sections, we will first describe where the
5172 various <tt>shlibs</tt> files are to be found, then how to
5173 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5174 file format and how to create them if your package contains a
5179 <heading>The <tt>shlibs</tt> files present on the system</heading>
5182 There are several places where <tt>shlibs</tt> files are
5183 found. The following list gives them in the order in which
5185 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5186 (The first one which gives the required information is used.)
5192 <p><file>debian/shlibs.local</file></p>
5195 This lists overrides for this package. Its use is
5196 described below (see <ref id="shlibslocal">).
5201 <p><file>/etc/dpkg/shlibs.override</file></p>
5204 This lists global overrides. This list is normally
5205 empty. It is maintained by the local system
5211 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5214 When packages are being built, any
5215 <file>debian/shlibs</file> files are copied into the
5216 control file area of the temporary build directory and
5217 given the name <file>shlibs</file>. These files give
5218 details of any shared libraries included in the
5220 An example may help here. Let us say that the
5221 source package <tt>foo</tt> generates two binary
5222 packages, <tt>libfoo2</tt> and
5223 <tt>foo-runtime</tt>. When building the binary
5224 packages, the two packages are created in the
5225 directories <file>debian/libfoo2</file> and
5226 <file>debian/foo-runtime</file> respectively.
5227 (<file>debian/tmp</file> could be used instead of one
5228 of these.) Since <tt>libfoo2</tt> provides the
5229 <tt>libfoo</tt> shared library, it will require a
5230 <tt>shlibs</tt> file, which will be installed in
5231 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5233 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5234 when <prgn>dpkg-shlibdeps</prgn> is run on the
5236 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5238 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5239 determine whether <tt>foo-prog</tt>'s library
5240 dependencies are satisfied by any of the libraries
5241 provided by <tt>libfoo2</tt>. For this reason,
5242 <prgn>dpkg-shlibdeps</prgn> must only be run once
5243 all of the individual binary packages'
5244 <tt>shlibs</tt> files have been installed into the
5251 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5254 These are the <file>shlibs</file> files corresponding to
5255 all of the packages installed on the system, and are
5256 maintained by the relevant package maintainers.
5261 <p><file>/etc/dpkg/shlibs.default</file></p>
5264 This file lists any shared libraries whose packages
5265 have failed to provide correct <file>shlibs</file> files.
5266 It was used when the <file>shlibs</file> setup was first
5267 introduced, but it is now normally empty. It is
5268 maintained by the <tt>dpkg</tt> maintainer.
5276 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5277 <file>shlibs</file> files</heading>
5281 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5282 into your <file>debian/rules</file> file. If your package
5283 contains only compiled binaries and libraries (but no scripts),
5284 you can use a command such as:
5285 <example compact="compact">
5286 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5287 debian/tmp/usr/lib/*
5289 Otherwise, you will need to explicitly list the compiled
5290 binaries and libraries.<footnote>
5291 If you are using <tt>debhelper</tt>, the
5292 <prgn>dh_shlibdeps</prgn> program will do this work for
5293 you. It will also correctly handle multi-binary
5299 This command puts the dependency information into the
5300 <file>debian/substvars</file> file, which is then used by
5301 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5302 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5303 field in the control file for this to work.
5307 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5308 done. If it does complain you might need to create your own
5309 <file>debian/shlibs.local</file> file, as explained below (see
5310 <ref id="shlibslocal">).
5314 If you have multiple binary packages, you will need to call
5315 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5316 compiled libraries or binaries. In such a case, you will
5317 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5318 utilities to specify a different <file>substvars</file> file.
5322 If you are creating a udeb for use in the Debian Installer, you
5323 will need to specify that <prgn>dpkg-shlibdeps</prgn> should use
5324 the dependency line of type <tt>udeb</tt> by adding
5325 <tt>-tudeb</tt> as option<footnote>
5326 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5327 will automatically add this option if it knows it is
5329 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5330 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5331 fall back to the regular dependency line.
5335 For more details on dpkg-shlibdeps, please see
5336 <ref id="pkg-dpkg-shlibdeps"> and
5337 <manref name="dpkg-shlibdeps" section="1">.
5342 <heading>The <file>shlibs</file> File Format</heading>
5345 Each <file>shlibs</file> file has the same format. Lines
5346 beginning with <tt>#</tt> are considered to be comments and
5347 are ignored. Each line is of the form:
5348 <example compact="compact">
5349 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5354 We will explain this by reference to the example of the
5355 <tt>zlib1g</tt> package, which (at the time of writing)
5356 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5360 <var>type</var> is an optional element that indicates the type
5361 of package for which the line is valid. The only type currently
5362 in use is <tt>udeb</tt>. The colon and space after the type are
5367 <var>library-name</var> is the name of the shared library,
5368 in this case <tt>libz</tt>. (This must match the name part
5369 of the soname, see below.)
5373 <var>soname-version</var> is the version part of the soname of
5374 the library. The soname is the thing that must exactly match
5375 for the library to be recognized by the dynamic linker, and is
5377 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5378 example, <tt>libz.so.1</tt>.<footnote>
5379 This can be determined using the command
5380 <example compact="compact">
5381 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5384 The version part is the part which comes after
5385 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5389 <var>dependencies</var> has the same syntax as a dependency
5390 field in a binary package control file. It should give
5391 details of which packages are required to satisfy a binary
5392 built against the version of the library contained in the
5393 package. See <ref id="depsyntax"> for details.
5397 In our example, if the first version of the <tt>zlib1g</tt>
5398 package which contained a minor number of at least
5399 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5400 <tt>shlibs</tt> entry for this library could say:
5401 <example compact="compact">
5402 libz 1 zlib1g (>= 1:1.1.3)
5404 The version-specific dependency is to avoid warnings from
5405 the dynamic linker about using older shared libraries with
5410 As zlib1g also provides a udeb containing the shared library,
5411 there would also be a second line:
5412 <example compact="compact">
5413 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5419 <heading>Providing a <file>shlibs</file> file</heading>
5422 If your package provides a shared library, you need to create
5423 a <file>shlibs</file> file following the format described above.
5424 It is usual to call this file <file>debian/shlibs</file> (but if
5425 you have multiple binary packages, you might want to call it
5426 <file>debian/shlibs.<var>package</var></file> instead). Then
5427 let <file>debian/rules</file> install it in the control area:
5428 <example compact="compact">
5429 install -m644 debian/shlibs debian/tmp/DEBIAN
5431 or, in the case of a multi-binary package:
5432 <example compact="compact">
5433 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5435 An alternative way of doing this is to create the
5436 <file>shlibs</file> file in the control area directly from
5437 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5438 file at all,<footnote>
5439 This is what <prgn>dh_makeshlibs</prgn> in the
5440 <tt>debhelper</tt> suite does. If your package also has a udeb
5441 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5442 automatically generate the <tt>udeb:</tt> lines if you specify
5443 the name of the udeb with the <tt>--add-udeb</tt> option.
5445 since the <file>debian/shlibs</file> file itself is ignored by
5446 <prgn>dpkg-shlibdeps</prgn>.
5450 As <prgn>dpkg-shlibdeps</prgn> reads the
5451 <file>DEBIAN/shlibs</file> files in all of the binary packages
5452 being built from this source package, all of the
5453 <file>DEBIAN/shlibs</file> files should be installed before
5454 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5459 <sect1 id="shlibslocal">
5460 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5463 This file is intended only as a <em>temporary</em> fix if
5464 your binaries or libraries depend on a library whose package
5465 does not yet provide a correct <file>shlibs</file> file.
5469 We will assume that you are trying to package a binary
5470 <tt>foo</tt>. When you try running
5471 <prgn>dpkg-shlibdeps</prgn> you get the following error
5472 message (<tt>-O</tt> displays the dependency information on
5473 <tt>stdout</tt> instead of writing it to
5474 <tt>debian/substvars</tt>, and the lines have been wrapped
5475 for ease of reading):
5476 <example compact="compact">
5477 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5478 dpkg-shlibdeps: warning: unable to find dependency
5479 information for shared library libbar (soname 1,
5480 path /usr/lib/libbar.so.1, dependency field Depends)
5481 shlibs:Depends=libc6 (>= 2.2.2-2)
5483 You can then run <prgn>ldd</prgn> on the binary to find the
5484 full location of the library concerned:
5485 <example compact="compact">
5487 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5488 libc.so.6 => /lib/libc.so.6 (0x40032000)
5489 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5491 So the <prgn>foo</prgn> binary depends on the
5492 <prgn>libbar</prgn> shared library, but no package seems to
5493 provide a <file>*.shlibs</file> file handling
5494 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5495 determine the package responsible:
5496 <example compact="compact">
5497 $ dpkg -S /usr/lib/libbar.so.1
5498 bar1: /usr/lib/libbar.so.1
5499 $ dpkg -s bar1 | grep Version
5502 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5503 is the one we are using. Now we can file a bug against the
5504 <tt>bar1</tt> package and create our own
5505 <file>debian/shlibs.local</file> to locally fix the problem.
5506 Including the following line into your
5507 <file>debian/shlibs.local</file> file:
5508 <example compact="compact">
5509 libbar 1 bar1 (>= 1.0-1)
5511 should allow the package build to work.
5515 As soon as the maintainer of <tt>bar1</tt> provides a
5516 correct <file>shlibs</file> file, you should remove this line
5517 from your <file>debian/shlibs.local</file> file. (You should
5518 probably also then have a versioned <tt>Build-Depends</tt>
5519 on <tt>bar1</tt> to help ensure that others do not have the
5520 same problem building your package.)
5529 <chapt id="opersys"><heading>The Operating System</heading>
5532 <heading>File system hierarchy</heading>
5536 <heading>File System Structure</heading>
5539 The location of all installed files and directories must
5540 comply with the Filesystem Hierarchy Standard (FHS),
5541 version 2.3, with the exceptions noted below, and except
5542 where doing so would violate other terms of Debian
5543 Policy. The following exceptions to the FHS apply:
5548 The optional rules related to user specific
5549 configuration files for applications are stored in
5550 the user's home directory are relaxed. It is
5551 recommended that such files start with the
5552 '<tt>.</tt>' character (a "dot file"), and if an
5553 application needs to create more than one dot file
5554 then the preferred placement is in a subdirectory
5555 with a name starting with a '.' character, (a "dot
5556 directory"). In this case it is recommended the
5557 configuration files not start with the '.'
5563 The requirement for amd64 to use <file>/lib64</file>
5564 for 64 bit binaries is removed.
5569 The requirement that
5570 <file>/usr/local/share/man</file> be "synonymous"
5571 with <file>/usr/local/man</file> is relaxed to a
5576 The requirement that windowmanagers with a single
5577 configuration file call it <file>system.*wmrc</file>
5578 is removed, as is the restriction that the window
5579 manager subdirectory be named identically to the
5580 window manager name itself.
5585 The requirement that boot manager configuration
5586 files live in <file>/etc</file>, or at least are
5587 symlinked there, is relaxed to a recommendation.
5594 The version of this document referred here can be
5595 found in the <tt>debian-policy</tt> package or on <url
5596 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5597 name="FHS (Debian copy)"> alongside this manual (or, if
5598 you have the <package>debian-policy</package> installed,
5600 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5601 (local copy)">). The
5602 latest version, which may be a more recent version, may
5604 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5605 Specific questions about following the standard may be
5606 asked on the <tt>debian-devel</tt> mailing list, or
5607 referred to the FHS mailing list (see the
5608 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5614 <heading>Site-specific programs</heading>
5617 As mandated by the FHS, packages must not place any
5618 files in <file>/usr/local</file>, either by putting them in
5619 the file system archive to be unpacked by <prgn>dpkg</prgn>
5620 or by manipulating them in their maintainer scripts.
5624 However, the package may create empty directories below
5625 <file>/usr/local</file> so that the system administrator knows
5626 where to place site-specific files. These are not
5627 directories <em>in</em> <file>/usr/local</file>, but are
5628 children of directories in <file>/usr/local</file>. These
5629 directories (<file>/usr/local/*/dir/</file>)
5630 should be removed on package removal if they are
5635 Note, that this applies only to directories <em>below</em>
5636 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
5637 Packages must not create sub-directories in the directory
5638 <file>/usr/local</file> itself, except those listed in FHS,
5639 section 4.5. However, you may create directories below
5640 them as you wish. You must not remove any of the
5641 directories listed in 4.5, even if you created them.
5645 Since <file>/usr/local</file> can be mounted read-only from a
5646 remote server, these directories must be created and
5647 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5648 maintainer scripts and not be included in the
5649 <file>.deb</file> archive. These scripts must not fail if
5650 either of these operations fail.
5654 For example, the <tt>emacsen-common</tt> package could
5655 contain something like
5656 <example compact="compact">
5657 if [ ! -e /usr/local/share/emacs ]
5659 if mkdir /usr/local/share/emacs 2>/dev/null
5661 chown root:staff /usr/local/share/emacs
5662 chmod 2775 /usr/local/share/emacs
5666 in its <prgn>postinst</prgn> script, and
5667 <example compact="compact">
5668 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5669 rmdir /usr/local/share/emacs 2>/dev/null || true
5671 in the <prgn>prerm</prgn> script. (Note that this form is
5672 used to ensure that if the script is interrupted, the
5673 directory <file>/usr/local/share/emacs</file> will still be
5678 If you do create a directory in <file>/usr/local</file> for
5679 local additions to a package, you should ensure that
5680 settings in <file>/usr/local</file> take precedence over the
5681 equivalents in <file>/usr</file>.
5685 However, because <file>/usr/local</file> and its contents are
5686 for exclusive use of the local administrator, a package
5687 must not rely on the presence or absence of files or
5688 directories in <file>/usr/local</file> for normal operation.
5692 The <file>/usr/local</file> directory itself and all the
5693 subdirectories created by the package should (by default) have
5694 permissions 2775 (group-writable and set-group-id) and be
5695 owned by <tt>root:staff</tt>.
5700 <heading>The system-wide mail directory</heading>
5702 The system-wide mail directory is <file>/var/mail</file>. This
5703 directory is part of the base system and should not owned
5704 by any particular mail agents. The use of the old
5705 location <file>/var/spool/mail</file> is deprecated, even
5706 though the spool may still be physically located there.
5712 <heading>Users and groups</heading>
5715 <heading>Introduction</heading>
5717 The Debian system can be configured to use either plain or
5722 Some user ids (UIDs) and group ids (GIDs) are reserved
5723 globally for use by certain packages. Because some
5724 packages need to include files which are owned by these
5725 users or groups, or need the ids compiled into binaries,
5726 these ids must be used on any Debian system only for the
5727 purpose for which they are allocated. This is a serious
5728 restriction, and we should avoid getting in the way of
5729 local administration policies. In particular, many sites
5730 allocate users and/or local system groups starting at 100.
5734 Apart from this we should have dynamically allocated ids,
5735 which should by default be arranged in some sensible
5736 order, but the behavior should be configurable.
5740 Packages other than <tt>base-passwd</tt> must not modify
5741 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5742 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5747 <heading>UID and GID classes</heading>
5749 The UID and GID numbers are divided into classes as
5755 Globally allocated by the Debian project, the same
5756 on every Debian system. These ids will appear in
5757 the <file>passwd</file> and <file>group</file> files of all
5758 Debian systems, new ids in this range being added
5759 automatically as the <tt>base-passwd</tt> package is
5764 Packages which need a single statically allocated
5765 uid or gid should use one of these; their
5766 maintainers should ask the <tt>base-passwd</tt>
5774 Dynamically allocated system users and groups.
5775 Packages which need a user or group, but can have
5776 this user or group allocated dynamically and
5777 differently on each system, should use <tt>adduser
5778 --system</tt> to create the group and/or user.
5779 <prgn>adduser</prgn> will check for the existence of
5780 the user or group, and if necessary choose an unused
5781 id based on the ranges specified in
5782 <file>adduser.conf</file>.
5786 <tag>1000-29999:</tag>
5789 Dynamically allocated user accounts. By default
5790 <prgn>adduser</prgn> will choose UIDs and GIDs for
5791 user accounts in this range, though
5792 <file>adduser.conf</file> may be used to modify this
5797 <tag>30000-59999:</tag>
5802 <tag>60000-64999:</tag>
5805 Globally allocated by the Debian project, but only
5806 created on demand. The ids are allocated centrally
5807 and statically, but the actual accounts are only
5808 created on users' systems on demand.
5812 These ids are for packages which are obscure or
5813 which require many statically-allocated ids. These
5814 packages should check for and create the accounts in
5815 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5816 <prgn>adduser</prgn> if it has this facility) if
5817 necessary. Packages which are likely to require
5818 further allocations should have a "hole" left after
5819 them in the allocation, to give them room to
5824 <tag>65000-65533:</tag>
5832 User <tt>nobody</tt>. The corresponding gid refers
5833 to the group <tt>nogroup</tt>.
5840 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5841 not</em> be used, because it is the error return
5850 <sect id="sysvinit">
5851 <heading>System run levels and <file>init.d</file> scripts</heading>
5853 <sect1 id="/etc/init.d">
5854 <heading>Introduction</heading>
5857 The <file>/etc/init.d</file> directory contains the scripts
5858 executed by <prgn>init</prgn> at boot time and when the
5859 init state (or "runlevel") is changed (see <manref
5860 name="init" section="8">).
5864 There are at least two different, yet functionally
5865 equivalent, ways of handling these scripts. For the sake
5866 of simplicity, this document describes only the symbolic
5867 link method. However, it must not be assumed by maintainer
5868 scripts that this method is being used, and any automated
5869 manipulation of the various runlevel behaviors by
5870 maintainer scripts must be performed using
5871 <prgn>update-rc.d</prgn> as described below and not by
5872 manually installing or removing symlinks. For information
5873 on the implementation details of the other method,
5874 implemented in the <tt>file-rc</tt> package, please refer
5875 to the documentation of that package.
5879 These scripts are referenced by symbolic links in the
5880 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5881 runlevels, <prgn>init</prgn> looks in the directory
5882 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5883 execute, where <tt><var>n</var></tt> is the runlevel that
5884 is being changed to, or <tt>S</tt> for the boot-up
5889 The names of the links all have the form
5890 <file>S<var>mm</var><var>script</var></file> or
5891 <file>K<var>mm</var><var>script</var></file> where
5892 <var>mm</var> is a two-digit number and <var>script</var>
5893 is the name of the script (this should be the same as the
5894 name of the actual script in <file>/etc/init.d</file>).
5898 When <prgn>init</prgn> changes runlevel first the targets
5899 of the links whose names start with a <tt>K</tt> are
5900 executed, each with the single argument <tt>stop</tt>,
5901 followed by the scripts prefixed with an <tt>S</tt>, each
5902 with the single argument <tt>start</tt>. (The links are
5903 those in the <file>/etc/rc<var>n</var>.d</file> directory
5904 corresponding to the new runlevel.) The <tt>K</tt> links
5905 are responsible for killing services and the <tt>S</tt>
5906 link for starting services upon entering the runlevel.
5910 For example, if we are changing from runlevel 2 to
5911 runlevel 3, init will first execute all of the <tt>K</tt>
5912 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5913 all of the <tt>S</tt> prefixed scripts in that directory.
5914 The links starting with <tt>K</tt> will cause the
5915 referred-to file to be executed with an argument of
5916 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5921 The two-digit number <var>mm</var> is used to determine
5922 the order in which to run the scripts: low-numbered links
5923 have their scripts run first. For example, the
5924 <tt>K20</tt> scripts will be executed before the
5925 <tt>K30</tt> scripts. This is used when a certain service
5926 must be started before another. For example, the name
5927 server <prgn>bind</prgn> might need to be started before
5928 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5929 can set up its access lists. In this case, the script
5930 that starts <prgn>bind</prgn> would have a lower number
5931 than the script that starts <prgn>inn</prgn> so that it
5933 <example compact="compact">
5940 The two runlevels 0 (halt) and 6 (reboot) are slightly
5941 different. In these runlevels, the links with an
5942 <tt>S</tt> prefix are still called after those with a
5943 <tt>K</tt> prefix, but they too are called with the single
5944 argument <tt>stop</tt>.
5949 <heading>Writing the scripts</heading>
5952 Packages that include daemons for system services should
5953 place scripts in <file>/etc/init.d</file> to start or stop
5954 services at boot time or during a change of runlevel.
5955 These scripts should be named
5956 <file>/etc/init.d/<var>package</var></file>, and they should
5957 accept one argument, saying what to do:
5960 <tag><tt>start</tt></tag>
5961 <item>start the service,</item>
5963 <tag><tt>stop</tt></tag>
5964 <item>stop the service,</item>
5966 <tag><tt>restart</tt></tag>
5967 <item>stop and restart the service if it's already running,
5968 otherwise start the service</item>
5970 <tag><tt>reload</tt></tag>
5971 <item><p>cause the configuration of the service to be
5972 reloaded without actually stopping and restarting
5975 <tag><tt>force-reload</tt></tag>
5976 <item>cause the configuration to be reloaded if the
5977 service supports this, otherwise restart the
5981 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
5982 <tt>force-reload</tt> options should be supported by all
5983 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
5988 The <file>init.d</file> scripts must ensure that they will
5989 behave sensibly (i.e., returning success and not starting
5990 multiple copies of a service) if invoked with <tt>start</tt>
5991 when the service is already running, or with <tt>stop</tt>
5992 when it isn't, and that they don't kill unfortunately-named
5993 user processes. The best way to achieve this is usually to
5994 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
5999 If a service reloads its configuration automatically (as
6000 in the case of <prgn>cron</prgn>, for example), the
6001 <tt>reload</tt> option of the <file>init.d</file> script
6002 should behave as if the configuration has been reloaded
6007 The <file>/etc/init.d</file> scripts must be treated as
6008 configuration files, either (if they are present in the
6009 package, that is, in the .deb file) by marking them as
6010 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6011 by managing them correctly in the maintainer scripts (see
6012 <ref id="config-files">). This is important since we want
6013 to give the local system administrator the chance to adapt
6014 the scripts to the local system, e.g., to disable a
6015 service without de-installing the package, or to specify
6016 some special command line options when starting a service,
6017 while making sure their changes aren't lost during the next
6022 These scripts should not fail obscurely when the
6023 configuration files remain but the package has been
6024 removed, as configuration files remain on the system after
6025 the package has been removed. Only when <prgn>dpkg</prgn>
6026 is executed with the <tt>--purge</tt> option will
6027 configuration files be removed. In particular, as the
6028 <file>/etc/init.d/<var>package</var></file> script itself is
6029 usually a <tt>conffile</tt>, it will remain on the system
6030 if the package is removed but not purged. Therefore, you
6031 should include a <tt>test</tt> statement at the top of the
6033 <example compact="compact">
6034 test -f <var>program-executed-later-in-script</var> || exit 0
6039 Often there are some variables in the <file>init.d</file>
6040 scripts whose values control the behavior of the scripts,
6041 and which a system administrator is likely to want to
6042 change. As the scripts themselves are frequently
6043 <tt>conffile</tt>s, modifying them requires that the
6044 administrator merge in their changes each time the package
6045 is upgraded and the <tt>conffile</tt> changes. To ease
6046 the burden on the system administrator, such configurable
6047 values should not be placed directly in the script.
6048 Instead, they should be placed in a file in
6049 <file>/etc/default</file>, which typically will have the same
6050 base name as the <file>init.d</file> script. This extra file
6051 should be sourced by the script when the script runs. It
6052 must contain only variable settings and comments in SUSv3
6053 <prgn>sh</prgn> format. It may either be a
6054 <tt>conffile</tt> or a configuration file maintained by
6055 the package maintainer scripts. See <ref id="config-files">
6060 To ensure that vital configurable values are always
6061 available, the <file>init.d</file> script should set default
6062 values for each of the shell variables it uses, either
6063 before sourcing the <file>/etc/default/</file> file or
6064 afterwards using something like the <tt>:
6065 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6066 script must behave sensibly and not fail if the
6067 <file>/etc/default</file> file is deleted.
6071 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6072 as temporary filesystems<footnote>
6073 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6074 options in <file>/etc/default/rcS</file>.
6075 </footnote>, so the <file>init.d</file> scripts must handle this
6076 correctly. This will typically amount to creating any required
6077 subdirectories dynamically when the <file>init.d</file> script
6078 is run, rather than including them in the package and relying on
6079 <prgn>dpkg</prgn> to create them.
6084 <heading>Interfacing with the initscript system</heading>
6087 Maintainers should use the abstraction layer provided by
6088 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6089 programs to deal with initscripts in their packages'
6090 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6091 and <prgn>postrm</prgn>.
6095 Directly managing the /etc/rc?.d links and directly
6096 invoking the <file>/etc/init.d/</file> initscripts should
6097 be done only by packages providing the initscript
6098 subsystem (such as <prgn>sysv-rc</prgn> and
6099 <prgn>file-rc</prgn>).
6103 <heading>Managing the links</heading>
6106 The program <prgn>update-rc.d</prgn> is provided for
6107 package maintainers to arrange for the proper creation and
6108 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6109 or their functional equivalent if another method is being
6110 used. This may be used by maintainers in their packages'
6111 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6115 You must not include any <file>/etc/rc<var>n</var>.d</file>
6116 symbolic links in the actual archive or manually create or
6117 remove the symbolic links in maintainer scripts; you must
6118 use the <prgn>update-rc.d</prgn> program instead. (The
6119 former will fail if an alternative method of maintaining
6120 runlevel information is being used.) You must not include
6121 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6122 in the archive either. (Only the <tt>sysvinit</tt>
6127 By default <prgn>update-rc.d</prgn> will start services in
6128 each of the multi-user state runlevels (2, 3, 4, and 5)
6129 and stop them in the halt runlevel (0), the single-user
6130 runlevel (1) and the reboot runlevel (6). The system
6131 administrator will have the opportunity to customize
6132 runlevels by simply adding, moving, or removing the
6133 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6134 symbolic links are being used, or by modifying
6135 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6140 To get the default behavior for your package, put in your
6141 <prgn>postinst</prgn> script
6142 <example compact="compact">
6143 update-rc.d <var>package</var> defaults
6145 and in your <prgn>postrm</prgn>
6146 <example compact="compact">
6147 if [ "$1" = purge ]; then
6148 update-rc.d <var>package</var> remove
6150 </example>. Note that if your package changes runlevels
6151 or priority, you may have to remove and recreate the links,
6152 since otherwise the old links may persist. Refer to the
6153 documentation of <prgn>update-rc.d</prgn>.
6157 This will use a default sequence number of 20. If it does
6158 not matter when or in which order the <file>init.d</file>
6159 script is run, use this default. If it does, then you
6160 should talk to the maintainer of the <prgn>sysvinit</prgn>
6161 package or post to <tt>debian-devel</tt>, and they will
6162 help you choose a number.
6166 For more information about using <tt>update-rc.d</tt>,
6167 please consult its man page <manref name="update-rc.d"
6173 <heading>Running initscripts</heading>
6175 The program <prgn>invoke-rc.d</prgn> is provided to make
6176 it easier for package maintainers to properly invoke an
6177 initscript, obeying runlevel and other locally-defined
6178 constraints that might limit a package's right to start,
6179 stop and otherwise manage services. This program may be
6180 used by maintainers in their packages' scripts.
6184 The package maintainer scripts must use
6185 <prgn>invoke-rc.d</prgn> to invoke the
6186 <file>/etc/init.d/*</file> initscripts, instead of
6187 calling them directly.
6191 By default, <prgn>invoke-rc.d</prgn> will pass any
6192 action requests (start, stop, reload, restart...) to the
6193 <file>/etc/init.d</file> script, filtering out requests
6194 to start or restart a service out of its intended
6199 Most packages will simply need to change:
6200 <example compact="compact">/etc/init.d/<package>
6201 <action></example> in their <prgn>postinst</prgn>
6202 and <prgn>prerm</prgn> scripts to:
6203 <example compact="compact">
6204 if which invoke-rc.d >/dev/null 2>&1; then
6205 invoke-rc.d <var>package</var> <action>
6207 /etc/init.d/<var>package</var> <action>
6213 A package should register its initscript services using
6214 <prgn>update-rc.d</prgn> before it tries to invoke them
6215 using <prgn>invoke-rc.d</prgn>. Invocation of
6216 unregistered services may fail.
6220 For more information about using
6221 <prgn>invoke-rc.d</prgn>, please consult its man page
6222 <manref name="invoke-rc.d" section="8">.
6228 <heading>Boot-time initialization</heading>
6231 There used to be another directory, <file>/etc/rc.boot</file>,
6232 which contained scripts which were run once per machine
6233 boot. This has been deprecated in favour of links from
6234 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6235 described in <ref id="/etc/init.d">. Packages must not
6236 place files in <file>/etc/rc.boot</file>.
6241 <heading>Example</heading>
6244 An example on which you can base your
6245 <file>/etc/init.d</file> scripts is found in
6246 <file>/etc/init.d/skeleton</file>.
6253 <heading>Console messages from <file>init.d</file> scripts</heading>
6256 This section describes the formats to be used for messages
6257 written to standard output by the <file>/etc/init.d</file>
6258 scripts. The intent is to improve the consistency of
6259 Debian's startup and shutdown look and feel. For this
6260 reason, please look very carefully at the details. We want
6261 the messages to have the same format in terms of wording,
6262 spaces, punctuation and case of letters.
6266 Here is a list of overall rules that should be used for
6267 messages generated by <file>/etc/init.d</file> scripts.
6273 The message should fit in one line (fewer than 80
6274 characters), start with a capital letter and end with
6275 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6279 If the script is performing some time consuming task in
6280 the background (not merely starting or stopping a
6281 program, for instance), an ellipsis (three dots:
6282 <tt>...</tt>) should be output to the screen, with no
6283 leading or tailing whitespace or line feeds.
6287 The messages should appear as if the computer is telling
6288 the user what it is doing (politely :-), but should not
6289 mention "it" directly. For example, instead of:
6290 <example compact="compact">
6291 I'm starting network daemons: nfsd mountd.
6293 the message should say
6294 <example compact="compact">
6295 Starting network daemons: nfsd mountd.
6302 <tt>init.d</tt> script should use the following standard
6303 message formats for the situations enumerated below.
6309 <p>When daemons are started</p>
6312 If the script starts one or more daemons, the output
6313 should look like this (a single line, no leading
6315 <example compact="compact">
6316 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6318 The <var>description</var> should describe the
6319 subsystem the daemon or set of daemons are part of,
6320 while <var>daemon-1</var> up to <var>daemon-n</var>
6321 denote each daemon's name (typically the file name of
6326 For example, the output of <file>/etc/init.d/lpd</file>
6328 <example compact="compact">
6329 Starting printer spooler: lpd.
6334 This can be achieved by saying
6335 <example compact="compact">
6336 echo -n "Starting printer spooler: lpd"
6337 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6340 in the script. If there are more than one daemon to
6341 start, the output should look like this:
6342 <example compact="compact">
6343 echo -n "Starting remote file system services:"
6344 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6345 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6346 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6349 This makes it possible for the user to see what is
6350 happening and when the final daemon has been started.
6351 Care should be taken in the placement of white spaces:
6352 in the example above the system administrators can
6353 easily comment out a line if they don't want to start
6354 a specific daemon, while the displayed message still
6360 <p>When a system parameter is being set</p>
6363 If you have to set up different system parameters
6364 during the system boot, you should use this format:
6365 <example compact="compact">
6366 Setting <var>parameter</var> to "<var>value</var>".
6371 You can use a statement such as the following to get
6373 <example compact="compact">
6374 echo "Setting DNS domainname to \"$domainname\"."
6379 Note that the same symbol (<tt>"</tt>) is used for the left
6380 and right quotation marks. A grave accent (<tt>`</tt>) is
6381 not a quote character; neither is an apostrophe
6387 <p>When a daemon is stopped or restarted</p>
6390 When you stop or restart a daemon, you should issue a
6391 message identical to the startup message, except that
6392 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6393 or <tt>Restarting</tt> respectively.
6397 For example, stopping the printer daemon will look like
6399 <example compact="compact">
6400 Stopping printer spooler: lpd.
6406 <p>When something is executed</p>
6409 There are several examples where you have to run a
6410 program at system startup or shutdown to perform a
6411 specific task, for example, setting the system's clock
6412 using <prgn>netdate</prgn> or killing all processes
6413 when the system shuts down. Your message should look
6415 <example compact="compact">
6416 Doing something very useful...done.
6418 You should print the <tt>done.</tt> immediately after
6419 the job has been completed, so that the user is
6420 informed why they have to wait. You can get this
6422 <example compact="compact">
6423 echo -n "Doing something very useful..."
6432 <p>When the configuration is reloaded</p>
6435 When a daemon is forced to reload its configuration
6436 files you should use the following format:
6437 <example compact="compact">
6438 Reloading <var>description</var> configuration...done.
6440 where <var>description</var> is the same as in the
6441 daemon starting message.
6449 <heading>Cron jobs</heading>
6452 Packages must not modify the configuration file
6453 <file>/etc/crontab</file>, and they must not modify the files in
6454 <file>/var/spool/cron/crontabs</file>.</p>
6457 If a package wants to install a job that has to be executed
6458 via cron, it should place a file with the name of the
6459 package in one or more of the following directories:
6460 <example compact="compact">
6466 As these directory names imply, the files within them are
6467 executed on an hourly, daily, weekly, or monthly basis,
6468 respectively. The exact times are listed in
6469 <file>/etc/crontab</file>.</p>
6472 All files installed in any of these directories must be
6473 scripts (e.g., shell scripts or Perl scripts) so that they
6474 can easily be modified by the local system administrator.
6475 In addition, they must be treated as configuration files.
6479 If a certain job has to be executed at some other frequency or
6480 at a specific time, the package should install a file
6481 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6482 same syntax as <file>/etc/crontab</file> and is processed by
6483 <prgn>cron</prgn> automatically. The file must also be
6484 treated as a configuration file. (Note that entries in the
6485 <file>/etc/cron.d</file> directory are not handled by
6486 <prgn>anacron</prgn>. Thus, you should only use this
6487 directory for jobs which may be skipped if the system is not
6491 The scripts or crontab entries in these directories should
6492 check if all necessary programs are installed before they
6493 try to execute them. Otherwise, problems will arise when a
6494 package was removed but not purged since configuration files
6495 are kept on the system in this situation.</p>
6499 <heading>Menus</heading>
6502 The Debian <tt>menu</tt> package provides a standard
6503 interface between packages providing applications and
6504 <em>menu programs</em> (either X window managers or
6505 text-based menu programs such as <prgn>pdmenu</prgn>).
6509 All packages that provide applications that need not be
6510 passed any special command line arguments for normal
6511 operation should register a menu entry for those
6512 applications, so that users of the <tt>menu</tt> package
6513 will automatically get menu entries in their window
6514 managers, as well in shells like <tt>pdmenu</tt>.
6518 Menu entries should follow the current menu policy.
6522 The menu policy can be found in the <tt>menu-policy</tt>
6523 files in the <tt>debian-policy</tt> package.
6524 It is also available from the Debian web mirrors at
6525 <tt><url name="/doc/packaging-manuals/menu-policy/"
6526 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6530 Please also refer to the <em>Debian Menu System</em>
6531 documentation that comes with the <package>menu</package>
6532 package for information about how to register your
6538 <heading>Multimedia handlers</heading>
6541 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6542 is a mechanism for encoding files and data streams and
6543 providing meta-information about them, in particular their
6544 type (e.g. audio or video) and format (e.g. PNG, HTML,
6549 Registration of MIME type handlers allows programs like mail
6550 user agents and web browsers to invoke these handlers to
6551 view, edit or display MIME types they don't support directly.
6555 Packages which provide the ability to view/show/play,
6556 compose, edit or print MIME types should register themselves
6557 as such following the current MIME support policy.
6561 The MIME support policy can be found in the <tt>mime-policy</tt>
6562 files in the <tt>debian-policy</tt> package.
6563 It is also available from the Debian web mirrors at
6564 <tt><url name="/doc/packaging-manuals/mime-policy/"
6565 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6571 <heading>Keyboard configuration</heading>
6574 To achieve a consistent keyboard configuration so that all
6575 applications interpret a keyboard event the same way, all
6576 programs in the Debian distribution must be configured to
6577 comply with the following guidelines.
6581 The following keys must have the specified interpretations:
6584 <tag><tt><--</tt></tag>
6585 <item>delete the character to the left of the cursor</item>
6587 <tag><tt>Delete</tt></tag>
6588 <item>delete the character to the right of the cursor</item>
6590 <tag><tt>Control+H</tt></tag>
6591 <item>emacs: the help prefix</item>
6594 The interpretation of any keyboard events should be
6595 independent of the terminal that is used, be it a virtual
6596 console, an X terminal emulator, an rlogin/telnet session,
6601 The following list explains how the different programs
6602 should be set up to achieve this:
6608 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6612 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6616 X translations are set up to make
6617 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6618 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6619 is the vt220 escape code for the "delete character"
6620 key). This must be done by loading the X resources
6621 using <prgn>xrdb</prgn> on all local X displays, not
6622 using the application defaults, so that the
6623 translation resources used correspond to the
6624 <prgn>xmodmap</prgn> settings.
6628 The Linux console is configured to make
6629 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6630 generate <tt>ESC [ 3 ~</tt>.
6634 X applications are configured so that <tt><</tt>
6635 deletes left, and <tt>Delete</tt> deletes right. Motif
6636 applications already work like this.
6640 Terminals should have <tt>stty erase ^?</tt> .
6644 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6645 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6646 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6650 Emacs is programmed to map <tt>KB_Backspace</tt> or
6651 the <tt>stty erase</tt> character to
6652 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6653 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6654 <tt>^H</tt> to <tt>help</tt> as always.
6658 Other applications use the <tt>stty erase</tt>
6659 character and <tt>kdch1</tt> for the two delete keys,
6660 with ASCII DEL being "delete previous character" and
6661 <tt>kdch1</tt> being "delete character under
6669 This will solve the problem except for the following
6676 Some terminals have a <tt><--</tt> key that cannot
6677 be made to produce anything except <tt>^H</tt>. On
6678 these terminals Emacs help will be unavailable on
6679 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6680 character takes precedence in Emacs, and has been set
6681 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6682 available) can be used instead.
6686 Some operating systems use <tt>^H</tt> for <tt>stty
6687 erase</tt>. However, modern telnet versions and all
6688 rlogin versions propagate <tt>stty</tt> settings, and
6689 almost all UNIX versions honour <tt>stty erase</tt>.
6690 Where the <tt>stty</tt> settings are not propagated
6691 correctly, things can be made to work by using
6692 <tt>stty</tt> manually.
6696 Some systems (including previous Debian versions) use
6697 <prgn>xmodmap</prgn> to arrange for both
6698 <tt><--</tt> and <tt>Delete</tt> to generate
6699 <tt>KB_Delete</tt>. We can change the behavior of
6700 their X clients using the same X resources that we use
6701 to do it for our own clients, or configure our clients
6702 using their resources when things are the other way
6703 around. On displays configured like this
6704 <tt>Delete</tt> will not work, but <tt><--</tt>
6709 Some operating systems have different <tt>kdch1</tt>
6710 settings in their <tt>terminfo</tt> database for
6711 <tt>xterm</tt> and others. On these systems the
6712 <tt>Delete</tt> key will not work correctly when you
6713 log in from a system conforming to our policy, but
6714 <tt><--</tt> will.
6721 <heading>Environment variables</heading>
6724 A program must not depend on environment variables to get
6725 reasonable defaults. (That's because these environment
6726 variables would have to be set in a system-wide
6727 configuration file like <file>/etc/profile</file>, which is not
6728 supported by all shells.)
6732 If a program usually depends on environment variables for its
6733 configuration, the program should be changed to fall back to
6734 a reasonable default configuration if these environment
6735 variables are not present. If this cannot be done easily
6736 (e.g., if the source code of a non-free program is not
6737 available), the program must be replaced by a small
6738 "wrapper" shell script which sets the environment variables
6739 if they are not already defined, and calls the original program.
6743 Here is an example of a wrapper script for this purpose:
6745 <example compact="compact">
6747 BAR=${BAR:-/var/lib/fubar}
6749 exec /usr/lib/foo/foo "$@"
6754 Furthermore, as <file>/etc/profile</file> is a configuration
6755 file of the <prgn>base-files</prgn> package, other packages must
6756 not put any environment variables or other commands into that
6761 <sect id="doc-base">
6762 <heading>Registering Documents using doc-base</heading>
6765 The <package>doc-base</package> package implements a
6766 flexible mechanism for handling and presenting
6767 documentation. The recommended practice is for every Debian
6768 package that provides online documentation (other than just
6769 manual pages) to register these documents with
6770 <package>doc-base</package> by installing a
6771 <package>doc-base</package> control file via the
6772 <prgn/install-docs/ script at installation time and
6773 de-register the manuals again when the package is removed.
6776 Please refer to the documentation that comes with the
6777 <package>doc-base</package> package for information and
6786 <heading>Files</heading>
6789 <heading>Binaries</heading>
6792 Two different packages must not install programs with
6793 different functionality but with the same filenames. (The
6794 case of two programs having the same functionality but
6795 different implementations is handled via "alternatives" or
6796 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6797 <ref id="conflicts"> respectively.) If this case happens,
6798 one of the programs must be renamed. The maintainers should
6799 report this to the <tt>debian-devel</tt> mailing list and
6800 try to find a consensus about which program will have to be
6801 renamed. If a consensus cannot be reached, <em>both</em>
6802 programs must be renamed.
6806 By default, when a package is being built, any binaries
6807 created should include debugging information, as well as
6808 being compiled with optimization. You should also turn on
6809 as many reasonable compilation warnings as possible; this
6810 makes life easier for porters, who can then look at build
6811 logs for possible problems. For the C programming language,
6812 this means the following compilation parameters should be
6814 <example compact="compact">
6816 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6818 INSTALL = install -s # (or use strip on the files in debian/tmp)
6823 Note that by default all installed binaries should be stripped,
6824 either by using the <tt>-s</tt> flag to
6825 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6826 the binaries after they have been copied into
6827 <file>debian/tmp</file> but before the tree is made into a
6832 Although binaries in the build tree should be compiled with
6833 debugging information by default, it can often be difficult to
6834 debug programs if they are also subjected to compiler
6835 optimization. For this reason, it is recommended to support the
6836 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6837 (see <ref id="debianrules-options">). This variable can contain
6838 several flags to change how a package is compiled and built.
6842 It is up to the package maintainer to decide what
6843 compilation options are best for the package. Certain
6844 binaries (such as computationally-intensive programs) will
6845 function better with certain flags (<tt>-O3</tt>, for
6846 example); feel free to use them. Please use good judgment
6847 here. Don't use flags for the sake of it; only use them
6848 if there is good reason to do so. Feel free to override
6849 the upstream author's ideas about which compilation
6850 options are best: they are often inappropriate for our
6856 <sect id="libraries">
6857 <heading>Libraries</heading>
6860 If the package is <strong>architecture: any</strong>, then
6861 the shared library compilation and linking flags must have
6862 <tt>-fPIC</tt>, or the package shall not build on some of
6863 the supported architectures<footnote>
6865 If you are using GCC, <tt>-fPIC</tt> produces code with
6866 relocatable position independent code, which is required for
6867 most architectures to create a shared library, with i386 and
6868 perhaps some others where non position independent code is
6869 permitted in a shared library.
6872 Position independent code may have a performance penalty,
6873 especially on <tt>i386</tt>. However, in most cases the
6874 speed penalty must be measured against the memory wasted on
6875 the few architectures where non position independent code is
6878 </footnote>. Any exception to this rule must be discussed on
6879 the mailing list <em>debian-devel@lists.debian.org</em>, and
6880 a rough consensus obtained. The reasons for not compiling
6881 with <tt>-fPIC</tt> flag must be recorded in the file
6882 <tt>README.Debian</tt>, and care must be taken to either
6883 restrict the architecture or arrange for <tt>-fPIC</tt> to
6884 be used on architectures where it is required.<footnote>
6886 Some of the reasons why this might be required is if the
6887 library contains hand crafted assembly code that is not
6888 relocatable, the speed penalty is excessive for compute
6889 intensive libs, and similar reasons.
6894 As to the static libraries, the common case is not to have
6895 relocatable code, since there is no benefit, unless in specific
6896 cases; therefore the static version must not be compiled
6897 with the <tt>-fPIC</tt> flag. Any exception to this rule
6898 should be discussed on the mailing list
6899 <em>debian-devel@lists.debian.org</em>, and the reasons for
6900 compiling with the <tt>-fPIC</tt> flag must be recorded in
6901 the file <tt>README.Debian</tt>. <footnote>
6903 Some of the reasons for linking static libraries with
6904 the <tt>-fPIC</tt> flag are if, for example, one needs a
6905 Perl API for a library that is under rapid development,
6906 and has an unstable API, so shared libraries are
6907 pointless at this phase of the library's development. In
6908 that case, since Perl needs a library with relocatable
6909 code, it may make sense to create a static library with
6910 relocatable code. Another reason cited is if you are
6911 distilling various libraries into a common shared
6912 library, like <tt>mklibs</tt> does in the Debian
6918 In other words, if both a shared and a static library is
6919 being built, each source unit (<tt>*.c</tt>, for example,
6920 for C files) will need to be compiled twice, for the normal
6924 You must specify the gcc option <tt>-D_REENTRANT</tt>
6925 when building a library (either static or shared) to make
6926 the library compatible with LinuxThreads.
6930 Although not enforced by the build tools, shared libraries
6931 must be linked against all libraries that they use symbols from
6932 in the same way that binaries are. This ensures the correct
6933 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6934 system and guarantees that all libraries can be safely opened
6935 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6936 option <tt>-Wl,-z,defs</tt> when building a shared library.
6937 Since this option enforces symbol resolution at build time,
6938 a missing library reference will be caught early as a fatal
6943 All installed shared libraries should be stripped with
6944 <example compact="compact">
6945 strip --strip-unneeded <var>your-lib</var>
6947 (The option <tt>--strip-unneeded</tt> makes
6948 <prgn>strip</prgn> remove only the symbols which aren't
6949 needed for relocation processing.) Shared libraries can
6950 function perfectly well when stripped, since the symbols for
6951 dynamic linking are in a separate part of the ELF object
6953 You might also want to use the options
6954 <tt>--remove-section=.comment</tt> and
6955 <tt>--remove-section=.note</tt> on both shared libraries
6956 and executables, and <tt>--strip-debug</tt> on static
6962 Note that under some circumstances it may be useful to
6963 install a shared library unstripped, for example when
6964 building a separate package to support debugging.
6968 Shared object files (often <file>.so</file> files) that are not
6969 public libraries, that is, they are not meant to be linked
6970 to by third party executables (binaries of other packages),
6971 should be installed in subdirectories of the
6972 <file>/usr/lib</file> directory. Such files are exempt from the
6973 rules that govern ordinary shared libraries, except that
6974 they must not be installed executable and should be
6976 A common example are the so-called "plug-ins",
6977 internal shared objects that are dynamically loaded by
6978 programs using <manref name="dlopen" section="3">.
6983 An ever increasing number of packages are using
6984 <prgn>libtool</prgn> to do their linking. The latest GNU
6985 libtools (>= 1.3a) can take advantage of the metadata in the
6986 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
6987 files). The main advantage of <prgn>libtool</prgn>'s
6988 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
6989 store and subsequently access metadata with respect to the
6990 libraries it builds. <prgn>libtool</prgn> will search for
6991 those files, which contain a lot of useful information about
6992 a library (such as library dependency information for static
6993 linking). Also, they're <em>essential</em> for programs
6994 using <tt>libltdl</tt>.<footnote>
6995 Although <prgn>libtool</prgn> is fully capable of
6996 linking against shared libraries which don't have
6997 <tt>.la</tt> files, as it is a mere shell script it can
6998 add considerably to the build time of a
6999 <prgn>libtool</prgn>-using package if that shell script
7000 has to derive all this information from first principles
7001 for each library every time it is linked. With the
7002 advent of <prgn>libtool</prgn> version 1.4 (and to a
7003 lesser extent <prgn>libtool</prgn> version 1.3), the
7004 <file>.la</file> files also store information about
7005 inter-library dependencies which cannot necessarily be
7006 derived after the <file>.la</file> file is deleted.
7011 Packages that use <prgn>libtool</prgn> to create shared
7012 libraries should include the <file>.la</file> files in the
7013 <tt>-dev</tt> package, unless the package relies on
7014 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7015 the <tt>.la</tt> files must go in the run-time library
7020 You must make sure that you use only released versions of
7021 shared libraries to build your packages; otherwise other
7022 users will not be able to run your binaries
7023 properly. Producing source packages that depend on
7024 unreleased compilers is also usually a bad
7031 <heading>Shared libraries</heading>
7033 This section has moved to <ref id="sharedlibs">.
7039 <heading>Scripts</heading>
7042 All command scripts, including the package maintainer
7043 scripts inside the package and used by <prgn>dpkg</prgn>,
7044 should have a <tt>#!</tt> line naming the shell to be used
7049 In the case of Perl scripts this should be
7050 <tt>#!/usr/bin/perl</tt>.
7054 When scripts are installed into a directory in the system
7055 PATH, the script name should not include an extension such
7056 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7057 language currently used to implement it.
7060 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7061 should almost certainly start with <tt>set -e</tt> so that
7062 errors are detected. Every script should use
7063 <tt>set -e</tt> or check the exit status of <em>every</em>
7068 Scripts may assume that <file>/bin/sh</file> implements the
7069 SUSv3 Shell Command Language<footnote>
7070 Single UNIX Specification, version 3, which is also IEEE
7071 1003.1-2004 (POSIX), and is available on the World Wide Web
7072 from <url id="http://www.unix.org/version3/online.html"
7073 name="The Open Group"> after free
7074 registration.</footnote>
7075 plus the following additional features not mandated by
7077 These features are in widespread use in the Linux community
7078 and are implemented in all of bash, dash, and ksh, the most
7079 common shells users may wish to use as <file>/bin/sh</file>.
7082 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7083 must not generate a newline.</item>
7084 <item><tt>test</tt>, if implemented as a shell built-in, must
7085 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7087 <item><tt>local</tt> to create a scoped variable must be
7088 supported, including listing multiple variables in a single
7089 local command and assigning a value to a variable at the
7090 same time as localizing it. <tt>local</tt> may or
7091 may not preserve the variable value from an outer scope if
7092 no assignment is present. Uses such as:
7096 # ... use a, b, c, d ...
7099 must be supported and must set the value of <tt>c</tt> to
7103 If a shell script requires non-SUSv3 features from the shell
7104 interpreter other than those listed above, the appropriate shell
7105 must be specified in the first line of the script (e.g.,
7106 <tt>#!/bin/bash</tt>) and the package must depend on the package
7107 providing the shell (unless the shell package is marked
7108 "Essential", as in the case of <prgn>bash</prgn>).
7112 You may wish to restrict your script to SUSv3 features plus the
7113 above set when possible so that it may use <file>/bin/sh</file>
7114 as its interpreter. If your script works with <prgn>dash</prgn>
7115 (originally called <prgn>ash</prgn>), it probably complies with
7116 the above requirements, but if you are in doubt, use
7117 <file>/bin/bash</file>.
7121 Perl scripts should check for errors when making any
7122 system calls, including <tt>open</tt>, <tt>print</tt>,
7123 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7127 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7128 scripting languages. See <em>Csh Programming Considered
7129 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7130 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7131 If an upstream package comes with <prgn>csh</prgn> scripts
7132 then you must make sure that they start with
7133 <tt>#!/bin/csh</tt> and make your package depend on the
7134 <prgn>c-shell</prgn> virtual package.
7138 Any scripts which create files in world-writeable
7139 directories (e.g., in <file>/tmp</file>) must use a
7140 mechanism which will fail atomically if a file with the same
7141 name already exists.
7145 The Debian base system provides the <prgn>tempfile</prgn>
7146 and <prgn>mktemp</prgn> utilities for use by scripts for
7153 <heading>Symbolic links</heading>
7156 In general, symbolic links within a top-level directory
7157 should be relative, and symbolic links pointing from one
7158 top-level directory into another should be absolute. (A
7159 top-level directory is a sub-directory of the root
7160 directory <file>/</file>.)
7164 In addition, symbolic links should be specified as short as
7165 possible, i.e., link targets like <file>foo/../bar</file> are
7170 Note that when creating a relative link using
7171 <prgn>ln</prgn> it is not necessary for the target of the
7172 link to exist relative to the working directory you're
7173 running <prgn>ln</prgn> from, nor is it necessary to change
7174 directory to the directory where the link is to be made.
7175 Simply include the string that should appear as the target
7176 of the link (this will be a pathname relative to the
7177 directory in which the link resides) as the first argument
7182 For example, in your <prgn>Makefile</prgn> or
7183 <file>debian/rules</file>, you can do things like:
7184 <example compact="compact">
7185 ln -fs gcc $(prefix)/bin/cc
7186 ln -fs gcc debian/tmp/usr/bin/cc
7187 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7188 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7193 A symbolic link pointing to a compressed file should always
7194 have the same file extension as the referenced file. (For
7195 example, if a file <file>foo.gz</file> is referenced by a
7196 symbolic link, the filename of the link has to end with
7197 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7202 <heading>Device files</heading>
7205 Packages must not include device files in the package file
7210 If a package needs any special device files that are not
7211 included in the base system, it must call
7212 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7213 after notifying the user<footnote>
7214 This notification could be done via a (low-priority)
7215 debconf message, or an echo (printf) statement.
7220 Packages must not remove any device files in the
7221 <prgn>postrm</prgn> or any other script. This is left to the
7222 system administrator.
7226 Debian uses the serial devices
7227 <file>/dev/ttyS*</file>. Programs using the old
7228 <file>/dev/cu*</file> devices should be changed to use
7229 <file>/dev/ttyS*</file>.
7233 <sect id="config-files">
7234 <heading>Configuration files</heading>
7237 <heading>Definitions</heading>
7241 <tag>configuration file</tag>
7243 A file that affects the operation of a program, or
7244 provides site- or host-specific information, or
7245 otherwise customizes the behavior of a program.
7246 Typically, configuration files are intended to be
7247 modified by the system administrator (if needed or
7248 desired) to conform to local policy or to provide
7249 more useful site-specific behavior.
7252 <tag><tt>conffile</tt></tag>
7254 A file listed in a package's <tt>conffiles</tt>
7255 file, and is treated specially by <prgn>dpkg</prgn>
7256 (see <ref id="configdetails">).
7262 The distinction between these two is important; they are
7263 not interchangeable concepts. Almost all
7264 <tt>conffile</tt>s are configuration files, but many
7265 configuration files are not <tt>conffiles</tt>.
7269 As noted elsewhere, <file>/etc/init.d</file> scripts,
7270 <file>/etc/default</file> files, scripts installed in
7271 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7272 configuration installed in <file>/etc/cron.d</file> must be
7273 treated as configuration files. In general, any script that
7274 embeds configuration information is de-facto a configuration
7275 file and should be treated as such.
7280 <heading>Location</heading>
7283 Any configuration files created or used by your package
7284 must reside in <file>/etc</file>. If there are several,
7285 consider creating a subdirectory of <file>/etc</file>
7286 named after your package.
7290 If your package creates or uses configuration files
7291 outside of <file>/etc</file>, and it is not feasible to modify
7292 the package to use <file>/etc</file> directly, put the files
7293 in <file>/etc</file> and create symbolic links to those files
7294 from the location that the package requires.
7299 <heading>Behavior</heading>
7302 Configuration file handling must conform to the following
7304 <list compact="compact">
7306 local changes must be preserved during a package
7310 configuration files must be preserved when the
7311 package is removed, and only deleted when the
7318 The easy way to achieve this behavior is to make the
7319 configuration file a <tt>conffile</tt>. This is
7320 appropriate only if it is possible to distribute a default
7321 version that will work for most installations, although
7322 some system administrators may choose to modify it. This
7323 implies that the default version will be part of the
7324 package distribution, and must not be modified by the
7325 maintainer scripts during installation (or at any other
7330 In order to ensure that local changes are preserved
7331 correctly, no package may contain or make hard links to
7332 conffiles.<footnote>
7333 Rationale: There are two problems with hard links.
7334 The first is that some editors break the link while
7335 editing one of the files, so that the two files may
7336 unwittingly become unlinked and different. The second
7337 is that <prgn>dpkg</prgn> might break the hard link
7338 while upgrading <tt>conffile</tt>s.
7343 The other way to do it is via the maintainer scripts. In
7344 this case, the configuration file must not be listed as a
7345 <tt>conffile</tt> and must not be part of the package
7346 distribution. If the existence of a file is required for
7347 the package to be sensibly configured it is the
7348 responsibility of the package maintainer to provide
7349 maintainer scripts which correctly create, update and
7350 maintain the file and remove it on purge. (See <ref
7351 id="maintainerscripts"> for more information.) These
7352 scripts must be idempotent (i.e., must work correctly if
7353 <prgn>dpkg</prgn> needs to re-run them due to errors
7354 during installation or removal), must cope with all the
7355 variety of ways <prgn>dpkg</prgn> can call maintainer
7356 scripts, must not overwrite or otherwise mangle the user's
7357 configuration without asking, must not ask unnecessary
7358 questions (particularly during upgrades), and must
7359 otherwise be good citizens.
7363 The scripts are not required to configure every possible
7364 option for the package, but only those necessary to get
7365 the package running on a given system. Ideally the
7366 sysadmin should not have to do any configuration other
7367 than that done (semi-)automatically by the
7368 <prgn>postinst</prgn> script.
7372 A common practice is to create a script called
7373 <file><var>package</var>-configure</file> and have the
7374 package's <prgn>postinst</prgn> call it if and only if the
7375 configuration file does not already exist. In certain
7376 cases it is useful for there to be an example or template
7377 file which the maintainer scripts use. Such files should
7378 be in <file>/usr/share/<var>package</var></file> or
7379 <file>/usr/lib/<var>package</var></file> (depending on whether
7380 they are architecture-independent or not). There should
7381 be symbolic links to them from
7382 <file>/usr/share/doc/<var>package</var>/examples</file> if
7383 they are examples, and should be perfectly ordinary
7384 <prgn>dpkg</prgn>-handled files (<em>not</em>
7385 configuration files).
7389 These two styles of configuration file handling must
7390 not be mixed, for that way lies madness:
7391 <prgn>dpkg</prgn> will ask about overwriting the file
7392 every time the package is upgraded.
7397 <heading>Sharing configuration files</heading>
7400 Packages which specify the same file as a
7401 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7402 with each other. (This is an instance of the general rule
7403 about not sharing files. Note that neither alternatives
7404 nor diversions are likely to be appropriate in this case;
7405 in particular, <prgn>dpkg</prgn> does not handle diverted
7406 <tt>conffile</tt>s well.)
7410 The maintainer scripts must not alter a <tt>conffile</tt>
7411 of <em>any</em> package, including the one the scripts
7416 If two or more packages use the same configuration file
7417 and it is reasonable for both to be installed at the same
7418 time, one of these packages must be defined as
7419 <em>owner</em> of the configuration file, i.e., it will be
7420 the package which handles that file as a configuration
7421 file. Other packages that use the configuration file must
7422 depend on the owning package if they require the
7423 configuration file to operate. If the other package will
7424 use the configuration file if present, but is capable of
7425 operating without it, no dependency need be declared.
7429 If it is desirable for two or more related packages to
7430 share a configuration file <em>and</em> for all of the
7431 related packages to be able to modify that configuration
7432 file, then the following should be done:
7433 <enumlist compact="compact">
7435 One of the related packages (the "owning" package)
7436 will manage the configuration file with maintainer
7437 scripts as described in the previous section.
7440 The owning package should also provide a program
7441 that the other packages may use to modify the
7445 The related packages must use the provided program
7446 to make any desired modifications to the
7447 configuration file. They should either depend on
7448 the core package to guarantee that the configuration
7449 modifier program is available or accept gracefully
7450 that they cannot modify the configuration file if it
7451 is not. (This is in addition to the fact that the
7452 configuration file may not even be present in the
7459 Sometimes it's appropriate to create a new package which
7460 provides the basic infrastructure for the other packages
7461 and which manages the shared configuration files. (The
7462 <tt>sgml-base</tt> package is a good example.)
7467 <heading>User configuration files ("dotfiles")</heading>
7470 The files in <file>/etc/skel</file> will automatically be
7471 copied into new user accounts by <prgn>adduser</prgn>.
7472 No other program should reference the files in
7473 <file>/etc/skel</file>.
7477 Therefore, if a program needs a dotfile to exist in
7478 advance in <file>$HOME</file> to work sensibly, that dotfile
7479 should be installed in <file>/etc/skel</file> and treated as a
7484 However, programs that require dotfiles in order to
7485 operate sensibly are a bad thing, unless they do create
7486 the dotfiles themselves automatically.
7490 Furthermore, programs should be configured by the Debian
7491 default installation to behave as closely to the upstream
7492 default behavior as possible.
7496 Therefore, if a program in a Debian package needs to be
7497 configured in some way in order to operate sensibly, that
7498 should be done using a site-wide configuration file placed
7499 in <file>/etc</file>. Only if the program doesn't support a
7500 site-wide default configuration and the package maintainer
7501 doesn't have time to add it may a default per-user file be
7502 placed in <file>/etc/skel</file>.
7506 <file>/etc/skel</file> should be as empty as we can make it.
7507 This is particularly true because there is no easy (or
7508 necessarily desirable) mechanism for ensuring that the
7509 appropriate dotfiles are copied into the accounts of
7510 existing users when a package is installed.
7516 <heading>Log files</heading>
7518 Log files should usually be named
7519 <file>/var/log/<var>package</var>.log</file>. If you have many
7520 log files, or need a separate directory for permission
7521 reasons (<file>/var/log</file> is writable only by
7522 <file>root</file>), you should usually create a directory named
7523 <file>/var/log/<var>package</var></file> and place your log
7528 Log files must be rotated occasionally so that they don't
7529 grow indefinitely; the best way to do this is to drop a log
7530 rotation configuration file into the directory
7531 <file>/etc/logrotate.d</file> and use the facilities provided by
7532 logrotate.<footnote>
7534 The traditional approach to log files has been to set up
7535 <em>ad hoc</em> log rotation schemes using simple shell
7536 scripts and cron. While this approach is highly
7537 customizable, it requires quite a lot of sysadmin work.
7538 Even though the original Debian system helped a little
7539 by automatically installing a system which can be used
7540 as a template, this was deemed not enough.
7544 The use of <prgn>logrotate</prgn>, a program developed
7545 by Red Hat, is better, as it centralizes log management.
7546 It has both a configuration file
7547 (<file>/etc/logrotate.conf</file>) and a directory where
7548 packages can drop their individual log rotation
7549 configurations (<file>/etc/logrotate.d</file>).
7552 Here is a good example for a logrotate config
7553 file (for more information see <manref name="logrotate"
7555 <example compact="compact">
7556 /var/log/foo/*.log {
7561 /etc/init.d/foo force-reload
7565 This rotates all files under <file>/var/log/foo</file>, saves 12
7566 compressed generations, and forces the daemon to reload its
7567 configuration information after the log rotation.
7571 Log files should be removed when the package is
7572 purged (but not when it is only removed). This should be
7573 done by the <prgn>postrm</prgn> script when it is called
7574 with the argument <tt>purge</tt> (see <ref
7575 id="removedetails">).
7580 <heading>Permissions and owners</heading>
7583 The rules in this section are guidelines for general use.
7584 If necessary you may deviate from the details below.
7585 However, if you do so you must make sure that what is done
7586 is secure and you should try to be as consistent as possible
7587 with the rest of the system. You should probably also
7588 discuss it on <prgn>debian-devel</prgn> first.
7592 Files should be owned by <tt>root:root</tt>, and made
7593 writable only by the owner and universally readable (and
7594 executable, if appropriate), that is mode 644 or 755.
7598 Directories should be mode 755 or (for group-writability)
7599 mode 2775. The ownership of the directory should be
7600 consistent with its mode: if a directory is mode 2775, it
7601 should be owned by the group that needs write access to
7604 When a package is upgraded, and the owner or permissions
7605 of a file included in the package has changed, dpkg
7606 arranges for the ownership and permissions to be
7607 correctly set upon installation. However, this does not
7608 extend to directories; the permissions and ownership of
7609 directories already on the system does not change on
7610 install or upgrade of packages. This makes sense, since
7611 otherwise common directories like <tt>/usr</tt> would
7612 always be in flux. To correctly change permissions of a
7613 directory the package owns, explicit action is required,
7614 usually in the <tt>postinst</tt> script. Care must be
7615 taken to handle downgrades as well, in that case.
7622 Setuid and setgid executables should be mode 4755 or 2755
7623 respectively, and owned by the appropriate user or group.
7624 They should not be made unreadable (modes like 4711 or
7625 2711 or even 4111); doing so achieves no extra security,
7626 because anyone can find the binary in the freely available
7627 Debian package; it is merely inconvenient. For the same
7628 reason you should not restrict read or execute permissions
7629 on non-set-id executables.
7633 Some setuid programs need to be restricted to particular
7634 sets of users, using file permissions. In this case they
7635 should be owned by the uid to which they are set-id, and by
7636 the group which should be allowed to execute them. They
7637 should have mode 4754; again there is no point in making
7638 them unreadable to those users who must not be allowed to
7643 It is possible to arrange that the system administrator can
7644 reconfigure the package to correspond to their local
7645 security policy by changing the permissions on a binary:
7646 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7647 described below.<footnote>
7648 Ordinary files installed by <prgn>dpkg</prgn> (as
7649 opposed to <tt>conffile</tt>s and other similar objects)
7650 normally have their permissions reset to the distributed
7651 permissions when the package is reinstalled. However,
7652 the use of <prgn>dpkg-statoverride</prgn> overrides this
7653 default behavior. If you use this method, you should
7654 remember to describe <prgn>dpkg-statoverride</prgn> in
7655 the package documentation; being a relatively new
7656 addition to Debian, it is probably not yet well-known.
7658 Another method you should consider is to create a group for
7659 people allowed to use the program(s) and make any setuid
7660 executables executable only by that group.
7664 If you need to create a new user or group for your package
7665 there are two possibilities. Firstly, you may need to
7666 make some files in the binary package be owned by this
7667 user or group, or you may need to compile the user or
7668 group id (rather than just the name) into the binary
7669 (though this latter should be avoided if possible, as in
7670 this case you need a statically allocated id).</p>
7673 If you need a statically allocated id, you must ask for a
7674 user or group id from the <tt>base-passwd</tt> maintainer,
7675 and must not release the package until you have been
7676 allocated one. Once you have been allocated one you must
7677 either make the package depend on a version of the
7678 <tt>base-passwd</tt> package with the id present in
7679 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7680 your package to create the user or group itself with the
7681 correct id (using <tt>adduser</tt>) in its
7682 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7683 the <prgn>postinst</prgn> is to be preferred if it is
7684 possible, otherwise a pre-dependency will be needed on the
7685 <tt>adduser</tt> package.)
7689 On the other hand, the program might be able to determine
7690 the uid or gid from the user or group name at runtime, so
7691 that a dynamically allocated id can be used. In this case
7692 you should choose an appropriate user or group name,
7693 discussing this on <prgn>debian-devel</prgn> and checking
7694 with the <package/base-passwd/ maintainer that it is unique and that
7695 they do not wish you to use a statically allocated id
7696 instead. When this has been checked you must arrange for
7697 your package to create the user or group if necessary using
7698 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7699 <prgn>postinst</prgn> script (again, the latter is to be
7700 preferred if it is possible).
7704 Note that changing the numeric value of an id associated
7705 with a name is very difficult, and involves searching the
7706 file system for all appropriate files. You need to think
7707 carefully whether a static or dynamic id is required, since
7708 changing your mind later will cause problems.
7711 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7713 This section is not intended as policy, but as a
7714 description of the use of <prgn>dpkg-statoverride</prgn>.
7718 If a system administrator wishes to have a file (or
7719 directory or other such thing) installed with owner and
7720 permissions different from those in the distributed Debian
7721 package, they can use the <prgn>dpkg-statoverride</prgn>
7722 program to instruct <prgn>dpkg</prgn> to use the different
7723 settings every time the file is installed. Thus the
7724 package maintainer should distribute the files with their
7725 normal permissions, and leave it for the system
7726 administrator to make any desired changes. For example, a
7727 daemon which is normally required to be setuid root, but
7728 in certain situations could be used without being setuid,
7729 should be installed setuid in the <tt>.deb</tt>. Then the
7730 local system administrator can change this if they wish.
7731 If there are two standard ways of doing it, the package
7732 maintainer can use <tt>debconf</tt> to find out the
7733 preference, and call <prgn>dpkg-statoverride</prgn> in the
7734 maintainer script if necessary to accommodate the system
7735 administrator's choice. Care must be taken during
7736 upgrades to not override an existing setting.
7740 Given the above, <prgn>dpkg-statoverride</prgn> is
7741 essentially a tool for system administrators and would not
7742 normally be needed in the maintainer scripts. There is
7743 one type of situation, though, where calls to
7744 <prgn>dpkg-statoverride</prgn> would be needed in the
7745 maintainer scripts, and that involves packages which use
7746 dynamically allocated user or group ids. In such a
7747 situation, something like the following idiom can be very
7748 helpful in the package's <prgn>postinst</prgn>, where
7749 <tt>sysuser</tt> is a dynamically allocated id:
7751 for i in /usr/bin/foo /usr/sbin/bar
7753 # only do something when no setting exists
7754 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7756 #include: debconf processing, question about foo and bar
7757 if [ "$RET" = "true" ] ; then
7758 dpkg-statoverride --update --add sysuser root 4755 $i
7763 The corresponding code to remove the override when the package
7766 for i in /usr/bin/foo /usr/sbin/bar
7768 if dpkg-statoverride --list $i >/dev/null 2>&1
7770 dpkg-statoverride --remove $i
7780 <chapt id="customized-programs">
7781 <heading>Customized programs</heading>
7783 <sect id="arch-spec">
7784 <heading>Architecture specification strings</heading>
7787 If a program needs to specify an <em>architecture specification
7788 string</em> in some place, it should select one of the
7789 strings provided by <tt>dpkg-architecture -L</tt>. The
7790 strings are in the format
7791 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7792 is sometimes elided, as when the OS is Linux.<footnote>
7793 <p>Currently, the strings are:
7794 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7795 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7796 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7797 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7798 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7799 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7800 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7801 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7802 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7803 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7804 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7805 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7806 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7807 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7808 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7809 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7810 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7811 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7812 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7813 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7814 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7815 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7816 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7817 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7818 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7819 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7820 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7821 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7822 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7823 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7824 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7825 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7826 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7827 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7828 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7829 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7830 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7836 Note that we don't want to use
7837 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7838 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7839 since this would make our programs incompatible with other
7840 Linux distributions. We also don't use something like
7841 <tt><var>arch</var>-unknown-linux</tt>, since the
7842 <tt>unknown</tt> does not look very good.
7847 <heading>Daemons</heading>
7850 The configuration files <file>/etc/services</file>,
7851 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7852 by the <prgn>netbase</prgn> package and must not be modified
7857 If a package requires a new entry in one of these files, the
7858 maintainer should get in contact with the
7859 <prgn>netbase</prgn> maintainer, who will add the entries
7860 and release a new version of the <prgn>netbase</prgn>
7865 The configuration file <file>/etc/inetd.conf</file> must not be
7866 modified by the package's scripts except via the
7867 <prgn>update-inetd</prgn> script or the
7868 <file>DebianNet.pm</file> Perl module. See their documentation
7869 for details on how to add entries.
7873 If a package wants to install an example entry into
7874 <file>/etc/inetd.conf</file>, the entry must be preceded with
7875 exactly one hash character (<tt>#</tt>). Such lines are
7876 treated as "commented out by user" by the
7877 <prgn>update-inetd</prgn> script and are not changed or
7878 activated during package updates.
7883 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7887 Some programs need to create pseudo-ttys. This should be done
7888 using Unix98 ptys if the C library supports it. The resulting
7889 program must not be installed setuid root, unless that
7890 is required for other functionality.
7894 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7895 <file>/var/log/lastlog</file> must be installed writable by
7896 group <tt>utmp</tt>. Programs which need to modify those
7897 files must be installed setgid <tt>utmp</tt>.
7902 <heading>Editors and pagers</heading>
7905 Some programs have the ability to launch an editor or pager
7906 program to edit or display a text document. Since there are
7907 lots of different editors and pagers available in the Debian
7908 distribution, the system administrator and each user should
7909 have the possibility to choose their preferred editor and
7914 In addition, every program should choose a good default
7915 editor/pager if none is selected by the user or system
7920 Thus, every program that launches an editor or pager must
7921 use the EDITOR or PAGER environment variable to determine
7922 the editor or pager the user wishes to use. If these
7923 variables are not set, the programs <file>/usr/bin/editor</file>
7924 and <file>/usr/bin/pager</file> should be used, respectively.
7928 These two files are managed through the <prgn>dpkg</prgn>
7929 "alternatives" mechanism. Thus every package providing an
7930 editor or pager must call the
7931 <prgn>update-alternatives</prgn> script to register these
7936 If it is very hard to adapt a program to make use of the
7937 EDITOR or PAGER variables, that program may be configured to
7938 use <file>/usr/bin/sensible-editor</file> and
7939 <file>/usr/bin/sensible-pager</file> as the editor or pager
7940 program respectively. These are two scripts provided in the
7941 Debian base system that check the EDITOR and PAGER variables
7942 and launch the appropriate program, and fall back to
7943 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
7944 variable is not set.
7948 A program may also use the VISUAL environment variable to
7949 determine the user's choice of editor. If it exists, it
7950 should take precedence over EDITOR. This is in fact what
7951 <file>/usr/bin/sensible-editor</file> does.
7955 It is not required for a package to depend on
7956 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
7957 package to provide such virtual packages.<footnote>
7958 The Debian base system already provides an editor and a
7964 <sect id="web-appl">
7965 <heading>Web servers and applications</heading>
7968 This section describes the locations and URLs that should
7969 be used by all web servers and web applications in the
7976 Cgi-bin executable files are installed in the
7978 <example compact="compact">
7979 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
7981 and should be referred to as
7982 <example compact="compact">
7983 http://localhost/cgi-bin/<var>cgi-bin-name</var>
7989 <p>Access to HTML documents</p>
7992 HTML documents for a package are stored in
7993 <file>/usr/share/doc/<var>package</var></file>
7994 and can be referred to as
7995 <example compact="compact">
7996 http://localhost/doc/<var>package</var>/<var>filename</var>
8001 The web server should restrict access to the document
8002 tree so that only clients on the same host can read
8003 the documents. If the web server does not support such
8004 access controls, then it should not provide access at
8005 all, or ask about providing access during installation.
8010 <p>Access to images</p>
8012 It is recommended that images for a package be stored
8013 in <tt>/usr/share/images/<var>package</var></tt> and
8014 may be referred to through an alias <tt>/images/</tt>
8017 http://localhost/images/<package>/<filename>
8024 <p>Web Document Root</p>
8027 Web Applications should try to avoid storing files in
8028 the Web Document Root. Instead they should use the
8029 /usr/share/doc/<var>package</var> directory for
8030 documents and register the Web Application via the
8031 <package>doc-base</package> package. If access to the
8032 web document root is unavoidable then use
8033 <example compact="compact">
8036 as the Document Root. This might be just a symbolic
8037 link to the location where the system administrator
8038 has put the real document root.
8041 <item><p>Providing httpd and/or httpd-cgi</p>
8043 All web servers should provide the virtual package
8044 <tt>httpd</tt>. If a web server has CGI support it should
8045 provide <tt>httpd-cgi</tt> additionally.
8048 All web applications which do not contain CGI scripts should
8049 depend on <tt>httpd</tt>, all those web applications which
8050 <tt>do</tt> contain CGI scripts, should depend on
8058 <sect id="mail-transport-agents">
8059 <heading>Mail transport, delivery and user agents</heading>
8062 Debian packages which process electronic mail, whether mail
8063 user agents (MUAs) or mail transport agents (MTAs), must
8064 ensure that they are compatible with the configuration
8065 decisions below. Failure to do this may result in lost
8066 mail, broken <tt>From:</tt> lines, and other serious brain
8071 The mail spool is <file>/var/mail</file> and the interface to
8072 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8073 the FHS). On older systems, the mail spool may be
8074 physically located in <file>/var/spool/mail</file>, but all
8075 access to the mail spool should be via the
8076 <file>/var/mail</file> symlink. The mail spool is part of the
8077 base system and not part of the MTA package.
8081 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8082 programs (such as IMAP daemons) must lock the mailbox in an
8083 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8084 be combined with dot locking. To avoid deadlocks, a program
8085 should use <tt>fcntl()</tt> first and dot locking after
8086 this, or alternatively implement the two locking methods in
8087 a non blocking way<footnote>
8088 If it is not possible to establish both locks, the
8089 system shouldn't wait for the second lock to be
8090 established, but remove the first lock, wait a (random)
8091 time, and start over locking again.
8092 </footnote>. Using the functions <tt>maillock</tt> and
8093 <tt>mailunlock</tt> provided by the
8094 <tt>liblockfile*</tt><footnote>
8095 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8096 to use these functions.
8097 </footnote> packages is the recommended way to realize this.
8101 Mailboxes are generally either mode 600 and owned by
8102 <var>user</var> or mode 660 and owned by
8103 <tt><var>user</var>:mail</tt><footnote>
8104 There are two traditional permission schemes for mail spools:
8105 mode 600 with all mail delivery done by processes running as
8106 the destination user, or mode 660 and owned by group mail with
8107 mail delivery done by a process running as a system user in
8108 group mail. Historically, Debian required mode 660 mail
8109 spools to enable the latter model, but that model has become
8110 increasingly uncommon and the principle of least privilege
8111 indicates that mail systems that use the first model should
8112 use permissions of 600. If delivery to programs is permitted,
8113 it's easier to keep the mail system secure if the delivery
8114 agent runs as the destination user. Debian Policy therefore
8115 permits either scheme.
8116 </footnote>. The local system administrator may choose a
8117 different permission scheme; packages should not make
8118 assumptions about the permission and ownership of mailboxes
8119 unless required (such as when creating a new mailbox). A MUA
8120 may remove a mailbox (unless it has nonstandard permissions) in
8121 which case the MTA or another MUA must recreate it if needed.
8125 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8126 be setgid mail to do the locking mentioned above (and
8127 must obviously avoid accessing other users' mailboxes
8128 using this privilege).</p>
8131 <file>/etc/aliases</file> is the source file for the system mail
8132 aliases (e.g., postmaster, usenet, etc.), it is the one
8133 which the sysadmin and <prgn>postinst</prgn> scripts may
8134 edit. After <file>/etc/aliases</file> is edited the program or
8135 human editing it must call <prgn>newaliases</prgn>. All MTA
8136 packages must come with a <prgn>newaliases</prgn> program,
8137 even if it does nothing, but older MTA packages did not do
8138 this so programs should not fail if <prgn>newaliases</prgn>
8139 cannot be found. Note that because of this, all MTA
8140 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8141 <tt>Replaces: mail-transport-agent</tt> control file
8146 The convention of writing <tt>forward to
8147 <var>address</var></tt> in the mailbox itself is not
8148 supported. Use a <tt>.forward</tt> file instead.</p>
8151 The <prgn>rmail</prgn> program used by UUCP
8152 for incoming mail should be <file>/usr/sbin/rmail</file>.
8153 Likewise, <prgn>rsmtp</prgn>, for receiving
8154 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8158 If your package needs to know what hostname to use on (for
8159 example) outgoing news and mail messages which are generated
8160 locally, you should use the file <file>/etc/mailname</file>. It
8161 will contain the portion after the username and <tt>@</tt>
8162 (at) sign for email addresses of users on the machine
8163 (followed by a newline).
8167 Such a package should check for the existence of this file
8168 when it is being configured. If it exists, it should be
8169 used without comment, although an MTA's configuration script
8170 may wish to prompt the user even if it finds that this file
8171 exists. If the file does not exist, the package should
8172 prompt the user for the value (preferably using
8173 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8174 as well as using it in the package's configuration. The
8175 prompt should make it clear that the name will not just be
8176 used by that package. For example, in this situation the
8177 <tt>inn</tt> package could say something like:
8178 <example compact="compact">
8179 Please enter the "mail name" of your system. This is the
8180 hostname portion of the address to be shown on outgoing
8181 news and mail messages. The default is
8182 <var>syshostname</var>, your system's host name. Mail
8183 name ["<var>syshostname</var>"]:
8185 where <var>syshostname</var> is the output of <tt>hostname
8191 <heading>News system configuration</heading>
8194 All the configuration files related to the NNTP (news)
8195 servers and clients should be located under
8196 <file>/etc/news</file>.</p>
8199 There are some configuration issues that apply to a number
8200 of news clients and server packages on the machine. These
8204 <tag><file>/etc/news/organization</file></tag>
8206 A string which should appear as the
8207 organization header for all messages posted
8208 by NNTP clients on the machine
8211 <tag><file>/etc/news/server</file></tag>
8213 Contains the FQDN of the upstream NNTP
8214 server, or localhost if the local machine is
8219 Other global files may be added as required for cross-package news
8226 <heading>Programs for the X Window System</heading>
8229 <heading>Providing X support and package priorities</heading>
8232 Programs that can be configured with support for the X
8233 Window System must be configured to do so and must declare
8234 any package dependencies necessary to satisfy their
8235 runtime requirements when using the X Window System. If
8236 such a package is of higher priority than the X packages
8237 on which it depends, it is required that either the
8238 X-specific components be split into a separate package, or
8239 that an alternative version of the package, which includes
8240 X support, be provided, or that the package's priority be
8246 <heading>Packages providing an X server</heading>
8249 Packages that provide an X server that, directly or
8250 indirectly, communicates with real input and display
8251 hardware should declare in their control data that they
8252 provide the virtual package <tt>xserver</tt>.<footnote>
8253 This implements current practice, and provides an
8254 actual policy for usage of the <tt>xserver</tt>
8255 virtual package which appears in the virtual packages
8256 list. In a nutshell, X servers that interface
8257 directly with the display and input hardware or via
8258 another subsystem (e.g., GGI) should provide
8259 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8260 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8266 <heading>Packages providing a terminal emulator</heading>
8269 Packages that provide a terminal emulator for the X Window
8270 System which meet the criteria listed below should declare
8271 in their control data that they provide the virtual
8272 package <tt>x-terminal-emulator</tt>. They should also
8273 register themselves as an alternative for
8274 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8279 To be an <tt>x-terminal-emulator</tt>, a program must:
8280 <list compact="compact">
8282 Be able to emulate a DEC VT100 terminal, or a
8283 compatible terminal.
8287 Support the command-line option <tt>-e
8288 <var>command</var></tt>, which creates a new
8289 terminal window<footnote>
8290 "New terminal window" does not necessarily mean
8291 a new top-level X window directly parented by
8292 the window manager; it could, if the terminal
8293 emulator application were so coded, be a new
8294 "view" in a multiple-document interface (MDI).
8296 and runs the specified <var>command</var>,
8297 interpreting the entirety of the rest of the command
8298 line as a command to pass straight to exec, in the
8299 manner that <tt>xterm</tt> does.
8303 Support the command-line option <tt>-T
8304 <var>title</var></tt>, which creates a new terminal
8305 window with the window title <var>title</var>.
8312 <heading>Packages providing a window manager</heading>
8315 Packages that provide a window manager should declare in
8316 their control data that they provide the virtual package
8317 <tt>x-window-manager</tt>. They should also register
8318 themselves as an alternative for
8319 <file>/usr/bin/x-window-manager</file>, with a priority
8320 calculated as follows:
8321 <list compact="compact">
8323 Start with a priority of 20.
8327 If the window manager supports the Debian menu
8328 system, add 20 points if this support is available
8329 in the package's default configuration (i.e., no
8330 configuration files belonging to the system or user
8331 have to be edited to activate the feature); if
8332 configuration files must be modified, add only 10
8338 If the window manager complies with <url
8339 id="http://www.freedesktop.org/Standards/wm-spec"
8340 name="The Window Manager Specification Project">,
8341 written by the <url id="http://www.freedesktop.org/"
8342 name="Free Desktop Group">, add 40 points.
8346 If the window manager permits the X session to be
8347 restarted using a <em>different</em> window manager
8348 (without killing the X server) in its default
8349 configuration, add 10 points; otherwise add none.
8356 <heading>Packages providing fonts</heading>
8359 Packages that provide fonts for the X Window
8361 For the purposes of Debian Policy, a "font for the X
8362 Window System" is one which is accessed via X protocol
8363 requests. Fonts for the Linux console, for PostScript
8364 renderer, or any other purpose, do not fit this
8365 definition. Any tool which makes such fonts available
8366 to the X Window System, however, must abide by this
8369 must do a number of things to ensure that they are both
8370 available without modification of the X or font server
8371 configuration, and that they do not corrupt files used by
8372 other font packages to register information about
8376 Fonts of any type supported by the X Window System
8377 must be in a separate binary package from any
8378 executables, libraries, or documentation (except
8379 that specific to the fonts shipped, such as their
8380 license information). If one or more of the fonts
8381 so packaged are necessary for proper operation of
8382 the package with which they are associated the font
8383 package may be Recommended; if the fonts merely
8384 provide an enhancement, a Suggests relationship may
8385 be used. Packages must not Depend on font
8387 This is because the X server may retrieve fonts
8388 from the local file system or over the network
8389 from an X font server; the Debian package system
8390 is empowered to deal only with the local
8396 BDF fonts must be converted to PCF fonts with the
8397 <prgn>bdftopcf</prgn> utility (available in the
8398 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8399 placed in a directory that corresponds to their
8401 <list compact="compact">
8403 100 dpi fonts must be placed in
8404 <file>/usr/share/fonts/X11/100dpi/</file>.
8408 75 dpi fonts must be placed in
8409 <file>/usr/share/fonts/X11/75dpi/</file>.
8413 Character-cell fonts, cursor fonts, and other
8414 low-resolution fonts must be placed in
8415 <file>/usr/share/fonts/X11/misc/</file>.
8421 Type 1 fonts must be placed in
8422 <file>/usr/share/fonts/X11/Type1/</file>. If font
8423 metric files are available, they must be placed here
8428 Subdirectories of <file>/usr/share/fonts/X11/</file>
8429 other than those listed above must be neither
8430 created nor used. (The <file>PEX</file>, <file>CID</file>,
8431 <file>Speedo</file>, and <file>cyrillic</file> directories
8432 are excepted for historical reasons, but installation of
8433 files into these directories remains discouraged.)
8437 Font packages may, instead of placing files directly
8438 in the X font directories listed above, provide
8439 symbolic links in that font directory pointing to
8440 the files' actual location in the filesystem. Such
8441 a location must comply with the FHS.
8445 Font packages should not contain both 75dpi and
8446 100dpi versions of a font. If both are available,
8447 they should be provided in separate binary packages
8448 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8449 the names of the packages containing the
8450 corresponding fonts.
8454 Fonts destined for the <file>misc</file> subdirectory
8455 should not be included in the same package as 75dpi
8456 or 100dpi fonts; instead, they should be provided in
8457 a separate package with <tt>-misc</tt> appended to
8462 Font packages must not provide the files
8463 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8464 <file>fonts.scale</file> in a font directory:
8467 <file>fonts.dir</file> files must not be provided at all.
8471 <file>fonts.alias</file> and <file>fonts.scale</file>
8472 files, if needed, should be provided in the
8474 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8475 where <var>fontdir</var> is the name of the
8477 <file>/usr/share/fonts/X11/</file> where the
8478 package's corresponding fonts are stored
8479 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8480 <var>package</var> is the name of the package
8481 that provides these fonts, and
8482 <var>extension</var> is either <tt>scale</tt>
8483 or <tt>alias</tt>, whichever corresponds to
8490 Font packages must declare a dependency on
8491 <tt>xfonts-utils</tt> in their control
8496 Font packages that provide one or more
8497 <file>fonts.scale</file> files as described above must
8498 invoke <prgn>update-fonts-scale</prgn> on each
8499 directory into which they installed fonts
8500 <em>before</em> invoking
8501 <prgn>update-fonts-dir</prgn> on that directory.
8502 This invocation must occur in both the
8503 <prgn>postinst</prgn> (for all arguments) and
8504 <prgn>postrm</prgn> (for all arguments except
8505 <tt>upgrade</tt>) scripts.
8509 Font packages that provide one or more
8510 <file>fonts.alias</file> files as described above must
8511 invoke <prgn>update-fonts-alias</prgn> on each
8512 directory into which they installed fonts. This
8513 invocation must occur in both the
8514 <prgn>postinst</prgn> (for all arguments) and
8515 <prgn>postrm</prgn> (for all arguments except
8516 <tt>upgrade</tt>) scripts.
8520 Font packages must invoke
8521 <prgn>update-fonts-dir</prgn> on each directory into
8522 which they installed fonts. This invocation must
8523 occur in both the <prgn>postinst</prgn> (for all
8524 arguments) and <prgn>postrm</prgn> (for all
8525 arguments except <tt>upgrade</tt>) scripts.
8529 Font packages must not provide alias names for the
8530 fonts they include which collide with alias names
8531 already in use by fonts already packaged.
8535 Font packages must not provide fonts with the same
8536 XLFD registry name as another font already packaged.
8542 <sect1 id="appdefaults">
8543 <heading>Application defaults files</heading>
8546 Application defaults files must be installed in the
8547 directory <file>/etc/X11/app-defaults/</file> (use of a
8548 localized subdirectory of <file>/etc/X11/</file> as described
8549 in the <em>X Toolkit Intrinsics - C Language
8550 Interface</em> manual is also permitted). They must be
8551 registered as <tt>conffile</tt>s or handled as
8552 configuration files.
8556 Customization of programs' X resources may also be
8557 supported with the provision of a file with the same name
8558 as that of the package placed in the
8559 <file>/etc/X11/Xresources/</file> directory, which must
8560 registered as a <tt>conffile</tt> or handled as a
8561 configuration file.<footnote>
8562 Note that this mechanism is not the same as using
8563 app-defaults; app-defaults are tied to the client
8564 binary on the local file system, whereas X resources
8565 are stored in the X server and affect all connecting
8572 <heading>Installation directory issues</heading>
8575 Historically, packages using the X Window System used a
8576 separate set of installation directories from other packages.
8577 This practice has been discontinued and packages using the X
8578 Window System should now generally be installed in the same
8579 directories as any other package. Specifically, packages must
8580 not install files under the <file>/usr/X11R6/</file> directory
8581 and the <file>/usr/X11R6/</file> directory hierarchy should be
8582 regarded as obsolete.
8586 Include files previously installed under
8587 <file>/usr/X11R6/include/X11/</file> should be installed into
8588 <file>/usr/include/X11/</file>. For files previously
8589 installed into subdirectories of
8590 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8591 determine if subdirectories of <file>/usr/lib/</file> and
8592 <file>/usr/share/</file> can be used. If not, a subdirectory
8593 of <file>/usr/lib/X11/</file> should be used.
8597 Configuration files for window, display, or session managers
8598 or other applications that are tightly integrated with the X
8599 Window System may be placed in a subdirectory
8600 of <file>/etc/X11/</file> corresponding to the package name.
8601 Other X Window System applications should use
8602 the <file>/etc/</file> directory unless otherwise mandated by
8603 policy (such as for <ref id="appdefaults">).
8608 <heading>The OSF/Motif and OpenMotif libraries</heading>
8611 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8612 OpenMotif libraries</em><footnote>
8613 OSF/Motif and OpenMotif are collectively referred to as
8614 "Motif" in this policy document.
8616 should be compiled against and tested with LessTif (a free
8617 re-implementation of Motif) instead. If the maintainer
8618 judges that the program or programs do not work
8619 sufficiently well with LessTif to be distributed and
8620 supported, but do so when compiled against Motif, then two
8621 versions of the package should be created; one linked
8622 statically against Motif and with <tt>-smotif</tt>
8623 appended to the package name, and one linked dynamically
8624 against Motif and with <tt>-dmotif</tt> appended to the
8629 Both Motif-linked versions are dependent
8630 upon non-DFSG-compliant software and thus cannot be
8631 uploaded to the <em>main</em> distribution; if the
8632 software is itself DFSG-compliant it may be uploaded to
8633 the <em>contrib</em> distribution. While known existing
8634 versions of Motif permit unlimited redistribution of
8635 binaries linked against the library (whether statically or
8636 dynamically), it is the package maintainer's
8637 responsibility to determine whether this is permitted by
8638 the license of the copy of Motif in their possession.
8644 <heading>Perl programs and modules</heading>
8647 Perl programs and modules should follow the current Perl policy.
8651 The Perl policy can be found in the <tt>perl-policy</tt>
8652 files in the <tt>debian-policy</tt> package.
8653 It is also available from the Debian web mirrors at
8654 <tt><url name="/doc/packaging-manuals/perl-policy/"
8655 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8660 <heading>Emacs lisp programs</heading>
8663 Please refer to the "Debian Emacs Policy" for details of how to
8664 package emacs lisp programs.
8668 The Emacs policy is available in
8669 <file>debian-emacs-policy.gz</file> of the
8670 <package>emacsen-common</package> package.
8671 It is also available from the Debian web mirrors at
8672 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8673 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8678 <heading>Games</heading>
8681 The permissions on <file>/var/games</file> are mode 755, owner
8682 <tt>root</tt> and group <tt>root</tt>.
8686 Each game decides on its own security policy.</p>
8689 Games which require protected, privileged access to
8690 high-score files, saved games, etc., may be made
8691 set-<em>group</em>-id (mode 2755) and owned by
8692 <tt>root:games</tt>, and use files and directories with
8693 appropriate permissions (770 <tt>root:games</tt>, for
8694 example). They must not be made
8695 set-<em>user</em>-id, as this causes security problems. (If
8696 an attacker can subvert any set-user-id game they can
8697 overwrite the executable of any other, causing other players
8698 of these games to run a Trojan horse program. With a
8699 set-group-id game the attacker only gets access to less
8700 important game data, and if they can get at the other
8701 players' accounts at all it will take considerably more
8705 Some packages, for example some fortune cookie programs, are
8706 configured by the upstream authors to install with their
8707 data files or other static information made unreadable so
8708 that they can only be accessed through set-id programs
8709 provided. You should not do this in a Debian package: anyone can
8710 download the <file>.deb</file> file and read the data from it,
8711 so there is no point making the files unreadable. Not
8712 making the files unreadable also means that you don't have
8713 to make so many programs set-id, which reduces the risk of a
8717 As described in the FHS, binaries of games should be
8718 installed in the directory <file>/usr/games</file>. This also
8719 applies to games that use the X Window System. Manual pages
8720 for games (X and non-X games) should be installed in
8721 <file>/usr/share/man/man6</file>.</p>
8727 <heading>Documentation</heading>
8730 <heading>Manual pages</heading>
8733 You should install manual pages in <prgn>nroff</prgn> source
8734 form, in appropriate places under <file>/usr/share/man</file>.
8735 You should only use sections 1 to 9 (see the FHS for more
8736 details). You must not install a pre-formatted "cat page".
8740 Each program, utility, and function should have an
8741 associated manual page included in the same package. It is
8742 suggested that all configuration files also have a manual
8743 page included as well. Manual pages for protocols and other
8744 auxiliary things are optional.
8748 If no manual page is available, this is considered as a bug
8749 and should be reported to the Debian Bug Tracking System (the
8750 maintainer of the package is allowed to write this bug report
8751 themselves, if they so desire). Do not close the bug report
8752 until a proper man page is available.<footnote>
8753 It is not very hard to write a man page. See the
8754 <url id="http://www.schweikhardt.net/man_page_howto.html"
8755 name="Man-Page-HOWTO">,
8756 <manref name="man" section="7">, the examples
8757 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8758 the helper programs <prgn>help2man</prgn>, or the
8759 directory <file>/usr/share/doc/man-db/examples</file>.
8764 You may forward a complaint about a missing man page to the
8765 upstream authors, and mark the bug as forwarded in the
8766 Debian bug tracking system. Even though the GNU Project do
8767 not in general consider the lack of a man page to be a bug,
8768 we do; if they tell you that they don't consider it a bug
8769 you should leave the bug in our bug tracking system open
8774 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8778 If one man page needs to be accessible via several names it
8779 is better to use a symbolic link than the <file>.so</file>
8780 feature, but there is no need to fiddle with the relevant
8781 parts of the upstream source to change from <file>.so</file> to
8782 symlinks: don't do it unless it's easy. You should not
8783 create hard links in the manual page directories, nor put
8784 absolute filenames in <file>.so</file> directives. The filename
8785 in a <file>.so</file> in a man page should be relative to the
8786 base of the man page tree (usually
8787 <file>/usr/share/man</file>). If you do not create any links
8788 (whether symlinks, hard links, or <tt>.so</tt> directives)
8789 in the file system to the alternate names of the man page,
8790 then you should not rely on <prgn>man</prgn> finding your
8791 man page under those names based solely on the information in
8792 the man page's header.<footnote>
8793 Supporting this in <prgn>man</prgn> often requires
8794 unreasonable processing time to find a manual page or to
8795 report that none exists, and moves knowledge into man's
8796 database that would be better left in the file system.
8797 This support is therefore deprecated and will cease to
8798 be present in the future.
8803 Manual pages in locale-specific subdirectories of
8804 <file>/usr/share/man</file> should use either UTF-8 or the usual
8805 legacy encoding for that language (normally the one corresponding
8806 to the shortest relevant locale name in
8807 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8808 <file>/usr/share/man/fr</file> should use either UTF-8 or
8809 ISO-8859-1.<footnote>
8810 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8811 use. In future, all manual pages will be required to use
8817 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8818 included in the subdirectory name unless it indicates a
8819 significant difference in the language, as this excludes
8820 speakers of the language in other countries.<footnote>
8821 At the time of writing, Chinese and Portuguese are the main
8822 languages with such differences, so <file>pt_BR</file>,
8823 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8828 If a localized version of a manual page is provided, it should
8829 either be up-to-date or it should be obvious to the reader that
8830 it is outdated and the original manual page should be used
8831 instead. This can be done either by a note at the beginning of
8832 the manual page or by showing the missing or changed portions in
8833 the original language instead of the target language.
8838 <heading>Info documents</heading>
8841 Info documents should be installed in <file>/usr/share/info</file>.
8842 They should be compressed with <tt>gzip -9</tt>.
8846 The <prgn>install-info</prgn> program maintains a directory of
8847 installed info documents in <file>/usr/share/info/dir</file> for
8848 the use of info readers.<footnote>
8849 It was previously necessary for packages installing info
8850 documents to run <prgn>install-info</prgn> from maintainer
8851 scripts. This is no longer necessary. The installation
8852 system now uses dpkg hooks.
8854 This file must not be included in packages.
8858 Info documents should contain section and directory entry
8859 information in the document for the use
8860 of <prgn>install-info</prgn>. The section should be specified
8861 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8862 space and the section of this info page. The directory entry or
8863 entries should be included between
8864 a <tt>START-INFO-DIR-ENTRY</tt> line and
8865 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8867 INFO-DIR-SECTION Individual utilities
8868 START-INFO-DIR-ENTRY
8869 * example: (example). An example info directory entry.
8872 To determine which section to use, you should look
8873 at <file>/usr/share/info/dir</file> on your system and choose
8874 the most relevant (or create a new section if none of the
8875 current sections are relevant).<footnote>
8876 Normally, info documents are generated from Texinfo source.
8877 To include this information in the generated info document, if
8878 it is absent, add commands like:
8880 @dircategory Individual utilities
8882 * example: (example). An example info directory entry.
8886 to the Texinfo source of the document and ensure that the info
8887 documents are rebuilt from source during the package build.
8892 <heading>Additional documentation</heading>
8895 Any additional documentation that comes with the package may
8896 be installed at the discretion of the package maintainer.
8897 Plain text documentation should be installed in the directory
8898 <file>/usr/share/doc/<var>package</var></file>, where
8899 <var>package</var> is the name of the package, and
8900 compressed with <tt>gzip -9</tt> unless it is small.
8904 If a package comes with large amounts of documentation which
8905 many users of the package will not require you should create
8906 a separate binary package to contain it, so that it does not
8907 take up disk space on the machines of users who do not need
8908 or want it installed.</p>
8911 It is often a good idea to put text information files
8912 (<file>README</file>s, changelogs, and so forth) that come with
8913 the source package in <file>/usr/share/doc/<var>package</var></file>
8914 in the binary package. However, you don't need to install
8915 the instructions for building and installing the package, of
8919 Packages must not require the existence of any files in
8920 <file>/usr/share/doc/</file> in order to function
8922 The system administrator should be able to
8923 delete files in <file>/usr/share/doc/</file> without causing
8924 any programs to break.
8926 Any files that are referenced by programs but are also
8927 useful as stand alone documentation should be installed under
8928 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8929 <file>/usr/share/doc/<var>package</var></file>.
8933 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8934 link to another directory in <file>/usr/share/doc</file> only if
8935 the two packages both come from the same source and the
8936 first package Depends on the second.<footnote>
8938 Please note that this does not override the section on
8939 changelog files below, so the file
8940 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8941 must refer to the changelog for the current version of
8942 <var>package</var> in question. In practice, this means
8943 that the sources of the target and the destination of the
8944 symlink must be the same (same source package and
8951 Former Debian releases placed all additional documentation
8952 in <file>/usr/doc/<var>package</var></file>. This has been
8953 changed to <file>/usr/share/doc/<var>package</var></file>,
8954 and packages must not put documentation in the directory
8955 <file>/usr/doc/<var>package</var></file>. <footnote>
8956 At this phase of the transition, we no longer require a
8957 symbolic link in <file>/usr/doc/</file>. At a later point,
8958 policy shall change to make the symbolic links a bug.
8964 <heading>Preferred documentation formats</heading>
8967 The unification of Debian documentation is being carried out
8971 If your package comes with extensive documentation in a
8972 markup format that can be converted to various other formats
8973 you should if possible ship HTML versions in a binary
8974 package, in the directory
8975 <file>/usr/share/doc/<var>appropriate-package</var></file> or
8976 its subdirectories.<footnote>
8977 The rationale: The important thing here is that HTML
8978 docs should be available in <em>some</em> package, not
8979 necessarily in the main binary package.
8984 Other formats such as PostScript may be provided at the
8985 package maintainer's discretion.
8989 <sect id="copyrightfile">
8990 <heading>Copyright information</heading>
8993 Every package must be accompanied by a verbatim copy of its
8994 copyright and distribution license in the file
8995 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
8996 file must neither be compressed nor be a symbolic link.
9000 In addition, the copyright file must say where the upstream
9001 sources (if any) were obtained. It should name the original
9002 authors of the package and the Debian maintainer(s) who were
9003 involved with its creation.
9007 Packages in the <em>contrib</em> or <em>non-free</em> archive
9008 areas should state in the copyright file that the package is not
9009 part of the Debian GNU/Linux distribution and briefly explain
9014 A copy of the file which will be installed in
9015 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9016 be in <file>debian/copyright</file> in the source package.
9020 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9021 link to another directory in <file>/usr/share/doc</file> only if
9022 the two packages both come from the same source and the
9023 first package Depends on the second. These rules are
9024 important because copyrights must be extractable by
9029 Packages distributed under the UCB BSD license, the Apache
9030 license (version 2.0), the Artistic license, the GNU GPL
9031 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9032 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9033 files under <file>/usr/share/common-licenses</file>,<footnote>
9036 <file>/usr/share/common-licenses/BSD</file>,
9037 <file>/usr/share/common-licenses/Apache-2.0</file>,
9038 <file>/usr/share/common-licenses/Artistic</file>,
9039 <file>/usr/share/common-licenses/GPL-2</file>,
9040 <file>/usr/share/common-licenses/GPL-3</file>,
9041 <file>/usr/share/common-licenses/LGPL-2</file>,
9042 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9043 <file>/usr/share/common-licenses/LGPL-3</file>,
9044 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9045 <file>/usr/share/common-licenses/GFDL-1.3</file>
9048 </footnote> rather than quoting them in the copyright
9053 You should not use the copyright file as a general <file>README</file>
9054 file. If your package has such a file it should be
9055 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9056 <file>README.Debian</file> or some other appropriate place.</p>
9060 <heading>Examples</heading>
9063 Any examples (configurations, source files, whatever),
9064 should be installed in a directory
9065 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9066 files should not be referenced by any program: they're there
9067 for the benefit of the system administrator and users as
9068 documentation only. Architecture-specific example files
9069 should be installed in a directory
9070 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9072 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9073 latter directory itself may be a symbolic link to the
9078 If the purpose of a package is to provide examples, then the
9079 example files may be installed into
9080 <file>/usr/share/doc/<var>package</var></file>.
9084 <sect id="changelogs">
9085 <heading>Changelog files</heading>
9088 Packages that are not Debian-native must contain a
9089 compressed copy of the <file>debian/changelog</file> file from
9090 the Debian source tree in
9091 <file>/usr/share/doc/<var>package</var></file> with the name
9092 <file>changelog.Debian.gz</file>.
9096 If an upstream changelog is available, it should be accessible as
9097 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9098 plain text. If the upstream changelog is distributed in
9099 HTML, it should be made available in that form as
9100 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9101 and a plain text <file>changelog.gz</file> should be generated
9102 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9103 the upstream changelog files do not already conform to this
9104 naming convention, then this may be achieved either by
9105 renaming the files, or by adding a symbolic link, at the
9106 maintainer's discretion.<footnote>
9107 Rationale: People should not have to look in places for
9108 upstream changelogs merely because they are given
9109 different names or are distributed in HTML format.
9114 All of these files should be installed compressed using
9115 <tt>gzip -9</tt>, as they will become large with time even
9116 if they start out small.
9120 If the package has only one changelog which is used both as
9121 the Debian changelog and the upstream one because there is
9122 no separate upstream maintainer then that changelog should
9123 usually be installed as
9124 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9125 there is a separate upstream maintainer, but no upstream
9126 changelog, then the Debian changelog should still be called
9127 <file>changelog.Debian.gz</file>.
9131 For details about the format and contents of the Debian
9132 changelog file, please see <ref id="dpkgchangelog">.
9137 <appendix id="pkg-scope">
9138 <heading>Introduction and scope of these appendices</heading>
9141 These appendices are taken essentially verbatim from the
9142 now-deprecated Packaging Manual, version 3.2.1.0. They are
9143 the chapters which are likely to be of use to package
9144 maintainers and which have not already been included in the
9145 policy document itself. Most of these sections are very likely
9146 not relevant to policy; they should be treated as
9147 documentation for the packaging system. Please note that these
9148 appendices are included for convenience, and for historical
9149 reasons: they used to be part of policy package, and they have
9150 not yet been incorporated into dpkg documentation. However,
9151 they still have value, and hence they are presented here.
9155 They have not yet been checked to ensure that they are
9156 compatible with the contents of policy, and if there are any
9157 contradictions, the version in the main policy document takes
9158 precedence. The remaining chapters of the old Packaging
9159 Manual have also not been read in detail to ensure that there
9160 are not parts which have been left out. Both of these will be
9165 Certain parts of the Packaging manual were integrated into the
9166 Policy Manual proper, and removed from the appendices. Links
9167 have been placed from the old locations to the new ones.
9171 <prgn>dpkg</prgn> is a suite of programs for creating binary
9172 package files and installing and removing them on Unix
9174 <prgn>dpkg</prgn> is targeted primarily at Debian
9175 GNU/Linux, but may work on or be ported to other
9181 The binary packages are designed for the management of
9182 installed executable programs (usually compiled binaries) and
9183 their associated data, though source code examples and
9184 documentation are provided as part of some packages.</p>
9187 This manual describes the technical aspects of creating Debian
9188 binary packages (<file>.deb</file> files). It documents the
9189 behavior of the package management programs
9190 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9191 they interact with packages.</p>
9194 It also documents the interaction between
9195 <prgn>dselect</prgn>'s core and the access method scripts it
9196 uses to actually install the selected packages, and describes
9197 how to create a new access method.</p>
9200 This manual does not go into detail about the options and
9201 usage of the package building and installation tools. It
9202 should therefore be read in conjunction with those programs'
9207 The utility programs which are provided with <prgn>dpkg</prgn>
9208 for managing various system configuration and similar issues,
9209 such as <prgn>update-rc.d</prgn> and
9210 <prgn>install-info</prgn>, are not described in detail here -
9211 please see their man pages.
9215 It is assumed that the reader is reasonably familiar with the
9216 <prgn>dpkg</prgn> System Administrators' manual.
9217 Unfortunately this manual does not yet exist.
9221 The Debian version of the FSF's GNU hello program is provided
9222 as an example for people wishing to create Debian
9223 packages. The Debian <prgn>debmake</prgn> package is
9224 recommended as a very helpful tool in creating and maintaining
9225 Debian packages. However, while the tools and examples are
9226 helpful, they do not replace the need to read and follow the
9227 Policy and Programmer's Manual.</p>
9230 <appendix id="pkg-binarypkg">
9231 <heading>Binary packages (from old Packaging Manual)</heading>
9234 The binary package has two main sections. The first part
9235 consists of various control information files and scripts used
9236 by <prgn>dpkg</prgn> when installing and removing. See <ref
9237 id="pkg-controlarea">.
9241 The second part is an archive containing the files and
9242 directories to be installed.
9246 In the future binary packages may also contain other
9247 components, such as checksums and digital signatures. The
9248 format for the archive is described in full in the
9249 <file>deb(5)</file> man page.
9253 <sect id="pkg-bincreating"><heading>Creating package files -
9254 <prgn>dpkg-deb</prgn>
9258 All manipulation of binary package files is done by
9259 <prgn>dpkg-deb</prgn>; it's the only program that has
9260 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9261 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9262 will spot that the options requested are appropriate to
9263 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9268 In order to create a binary package you must make a
9269 directory tree which contains all the files and directories
9270 you want to have in the file system data part of the package.
9271 In Debian-format source packages this directory is usually
9272 <file>debian/tmp</file>, relative to the top of the package's
9277 They should have the locations (relative to the root of the
9278 directory tree you're constructing) ownerships and
9279 permissions which you want them to have on the system when
9284 With current versions of <prgn>dpkg</prgn> the uid/username
9285 and gid/groupname mappings for the users and groups being
9286 used should be the same on the system where the package is
9287 built and the one where it is installed.
9291 You need to add one special directory to the root of the
9292 miniature file system tree you're creating:
9293 <prgn>DEBIAN</prgn>. It should contain the control
9294 information files, notably the binary package control file
9295 (see <ref id="pkg-controlfile">).
9299 The <prgn>DEBIAN</prgn> directory will not appear in the
9300 file system archive of the package, and so won't be installed
9301 by <prgn>dpkg</prgn> when the package is installed.
9305 When you've prepared the package, you should invoke:
9307 dpkg --build <var>directory</var>
9312 This will build the package in
9313 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9314 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9315 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9320 See the man page <manref name="dpkg-deb" section="8"> for details of how
9321 to examine the contents of this newly-created file. You may find the
9322 output of following commands enlightening:
9324 dpkg-deb --info <var>filename</var>.deb
9325 dpkg-deb --contents <var>filename</var>.deb
9326 dpkg --contents <var>filename</var>.deb
9328 To view the copyright file for a package you could use this command:
9330 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9335 <sect id="pkg-controlarea">
9336 <heading>Package control information files</heading>
9339 The control information portion of a binary package is a
9340 collection of files with names known to <prgn>dpkg</prgn>.
9341 It will treat the contents of these files specially - some
9342 of them contain information used by <prgn>dpkg</prgn> when
9343 installing or removing the package; others are scripts which
9344 the package maintainer wants <prgn>dpkg</prgn> to run.
9348 It is possible to put other files in the package control
9349 area, but this is not generally a good idea (though they
9350 will largely be ignored).
9354 Here is a brief list of the control info files supported by
9355 <prgn>dpkg</prgn> and a summary of what they're used for.
9360 <tag><tt>control</tt>
9363 This is the key description file used by
9364 <prgn>dpkg</prgn>. It specifies the package's name
9365 and version, gives its description for the user,
9366 states its relationships with other packages, and so
9367 forth. See <ref id="sourcecontrolfiles"> and
9368 <ref id="binarycontrolfiles">.
9372 It is usually generated automatically from information
9373 in the source package by the
9374 <prgn>dpkg-gencontrol</prgn> program, and with
9375 assistance from <prgn>dpkg-shlibdeps</prgn>.
9376 See <ref id="pkg-sourcetools">.
9380 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9385 These are executable files (usually scripts) which
9386 <prgn>dpkg</prgn> runs during installation, upgrade
9387 and removal of packages. They allow the package to
9388 deal with matters which are particular to that package
9389 or require more complicated processing than that
9390 provided by <prgn>dpkg</prgn>. Details of when and
9391 how they are called are in <ref id="maintainerscripts">.
9395 It is very important to make these scripts idempotent.
9396 See <ref id="idempotency">.
9400 The maintainer scripts are guaranteed to run with a
9401 controlling terminal and can interact with the user.
9402 See <ref id="controllingterminal">.
9406 <tag><tt>conffiles</tt>
9409 This file contains a list of configuration files which
9410 are to be handled automatically by <prgn>dpkg</prgn>
9411 (see <ref id="pkg-conffiles">). Note that not necessarily
9412 every configuration file should be listed here.
9415 <tag><tt>shlibs</tt>
9418 This file contains a list of the shared libraries
9419 supplied by the package, with dependency details for
9420 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9421 when it determines what dependencies are required in a
9422 package control file. The <tt>shlibs</tt> file format
9423 is described on <ref id="shlibs">.
9428 <sect id="pkg-controlfile">
9429 <heading>The main control information file: <tt>control</tt></heading>
9432 The most important control information file used by
9433 <prgn>dpkg</prgn> when it installs a package is
9434 <tt>control</tt>. It contains all the package's "vital
9439 The binary package control files of packages built from
9440 Debian sources are made by a special tool,
9441 <prgn>dpkg-gencontrol</prgn>, which reads
9442 <file>debian/control</file> and <file>debian/changelog</file> to
9443 find the information it needs. See <ref id="pkg-sourcepkg"> for
9448 The fields in binary package control files are listed in
9449 <ref id="binarycontrolfiles">.
9453 A description of the syntax of control files and the purpose
9454 of the fields is available in <ref id="controlfields">.
9459 <heading>Time Stamps</heading>
9462 See <ref id="timestamps">.
9467 <appendix id="pkg-sourcepkg">
9468 <heading>Source packages (from old Packaging Manual) </heading>
9471 The Debian binary packages in the distribution are generated
9472 from Debian sources, which are in a special format to assist
9473 the easy and automatic building of binaries.
9476 <sect id="pkg-sourcetools">
9477 <heading>Tools for processing source packages</heading>
9480 Various tools are provided for manipulating source packages;
9481 they pack and unpack sources and help build of binary
9482 packages and help manage the distribution of new versions.
9486 They are introduced and typical uses described here; see
9487 <manref name="dpkg-source" section="1"> for full
9488 documentation about their arguments and operation.
9492 For examples of how to construct a Debian source package,
9493 and how to use those utilities that are used by Debian
9494 source packages, please see the <prgn>hello</prgn> example
9498 <sect1 id="pkg-dpkg-source">
9500 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9505 This program is frequently used by hand, and is also
9506 called from package-independent automated building scripts
9507 such as <prgn>dpkg-buildpackage</prgn>.
9511 To unpack a package it is typically invoked with
9513 dpkg-source -x <var>.../path/to/filename</var>.dsc
9518 with the <file><var>filename</var>.tar.gz</file> and
9519 <file><var>filename</var>.diff.gz</file> (if applicable) in
9520 the same directory. It unpacks into
9521 <file><var>package</var>-<var>version</var></file>, and if
9523 <file><var>package</var>-<var>version</var>.orig</file>, in
9524 the current directory.
9528 To create a packed source archive it is typically invoked:
9530 dpkg-source -b <var>package</var>-<var>version</var>
9535 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9536 <file>.diff.gz</file> (if appropriate) in the current
9537 directory. <prgn>dpkg-source</prgn> does not clean the
9538 source tree first - this must be done separately if it is
9543 See also <ref id="pkg-sourcearchives">.</p>
9547 <sect1 id="pkg-dpkg-buildpackage">
9549 <prgn>dpkg-buildpackage</prgn> - overall package-building
9554 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9555 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9556 targets <tt>clean</tt>, <tt>build</tt> and
9557 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9558 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9559 source and binary package upload.
9563 It is usually invoked by hand from the top level of the
9564 built or unbuilt source directory. It may be invoked with
9565 no arguments; useful arguments include:
9566 <taglist compact="compact">
9567 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9570 Do not sign the <tt>.changes</tt> file or the
9571 source package <tt>.dsc</tt> file, respectively.</p>
9573 <tag><tt>-p<var>sign-command</var></tt></tag>
9576 Invoke <var>sign-command</var> instead of finding
9577 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9578 <var>sign-command</var> must behave just like
9579 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9581 <tag><tt>-r<var>root-command</var></tt></tag>
9584 When root privilege is required, invoke the command
9585 <var>root-command</var>. <var>root-command</var>
9586 should invoke its first argument as a command, from
9587 the <prgn>PATH</prgn> if necessary, and pass its
9588 second and subsequent arguments to the command it
9589 calls. If no <var>root-command</var> is supplied
9590 then <var>dpkg-buildpackage</var> will take no
9591 special action to gain root privilege, so that for
9592 most packages it will have to be invoked as root to
9595 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9598 Two types of binary-only build and upload - see
9599 <manref name="dpkg-source" section="1">.
9606 <sect1 id="pkg-dpkg-gencontrol">
9608 <prgn>dpkg-gencontrol</prgn> - generates binary package
9613 This program is usually called from <file>debian/rules</file>
9614 (see <ref id="pkg-sourcetree">) in the top level of the source
9619 This is usually done just before the files and directories in the
9620 temporary directory tree where the package is being built have their
9621 permissions and ownerships set and the package is constructed using
9622 <prgn>dpkg-deb/</prgn>
9624 This is so that the control file which is produced has
9625 the right permissions
9630 <prgn>dpkg-gencontrol</prgn> must be called after all the
9631 files which are to go into the package have been placed in
9632 the temporary build directory, so that its calculation of
9633 the installed size of a package is correct.
9637 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9638 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9639 variable substitutions created by
9640 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9645 For a package which generates only one binary package, and
9646 which builds it in <file>debian/tmp</file> relative to the top
9647 of the source package, it is usually sufficient to call
9648 <prgn>dpkg-gencontrol</prgn>.
9652 Sources which build several binaries will typically need
9655 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9656 </example> The <tt>-P</tt> tells
9657 <prgn>dpkg-gencontrol</prgn> that the package is being
9658 built in a non-default directory, and the <tt>-p</tt>
9659 tells it which package's control file should be generated.
9663 <prgn>dpkg-gencontrol</prgn> also adds information to the
9664 list of files in <file>debian/files</file>, for the benefit of
9665 (for example) a future invocation of
9666 <prgn>dpkg-genchanges</prgn>.</p>
9669 <sect1 id="pkg-dpkg-shlibdeps">
9671 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9676 This program is usually called from <file>debian/rules</file>
9677 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9678 id="pkg-sourcetree">), in the top level of the source tree.
9682 Its arguments are executables and shared libraries
9685 They may be specified either in the locations in the
9686 source tree where they are created or in the locations
9687 in the temporary build tree where they are installed
9688 prior to binary package creation.
9690 </footnote> for which shared library dependencies should
9691 be included in the binary package's control file.
9695 If some of the found shared libraries should only
9696 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9697 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9698 by using the <tt>-d<var>dependency-field</var></tt> option
9699 before those executable(s). (Each <tt>-d</tt> option
9700 takes effect until the next <tt>-d</tt>.)
9704 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9705 output control file to be modified. Instead by default it
9706 adds to the <file>debian/substvars</file> file variable
9707 settings like <tt>shlibs:Depends</tt>. These variable
9708 settings must be referenced in dependency fields in the
9709 appropriate per-binary-package sections of the source
9714 For example, a package that generates an essential part
9715 which requires dependencies, and optional parts that
9716 which only require a recommendation, would separate those
9717 two sets of dependencies into two different fields.<footnote>
9718 At the time of writing, an example for this was the
9719 <package/xmms/ package, with Depends used for the xmms
9720 executable, Recommends for the plug-ins and Suggests for
9721 even more optional features provided by unzip.
9723 It can say in its <file>debian/rules</file>:
9725 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9726 -dRecommends <var>optionalpart anotheroptionalpart</var>
9728 and then in its main control file <file>debian/control</file>:
9731 Depends: ${shlibs:Depends}
9732 Recommends: ${shlibs:Recommends}
9738 Sources which produce several binary packages with
9739 different shared library dependency requirements can use
9740 the <tt>-p<var>varnameprefix</var></tt> option to override
9741 the default <tt>shlibs:</tt> prefix (one invocation of
9742 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9743 They can thus produce several sets of dependency
9744 variables, each of the form
9745 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9746 which can be referred to in the appropriate parts of the
9747 binary package control files.
9752 <sect1 id="pkg-dpkg-distaddfile">
9754 <prgn>dpkg-distaddfile</prgn> - adds a file to
9755 <file>debian/files</file>
9759 Some packages' uploads need to include files other than
9760 the source and binary package files.
9764 <prgn>dpkg-distaddfile</prgn> adds a file to the
9765 <file>debian/files</file> file so that it will be included in
9766 the <file>.changes</file> file when
9767 <prgn>dpkg-genchanges</prgn> is run.
9771 It is usually invoked from the <tt>binary</tt> target of
9772 <file>debian/rules</file>:
9774 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9776 The <var>filename</var> is relative to the directory where
9777 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9778 is usually the directory above the top level of the source
9779 tree. The <file>debian/rules</file> target should put the
9780 file there just before or just after calling
9781 <prgn>dpkg-distaddfile</prgn>.
9785 The <var>section</var> and <var>priority</var> are passed
9786 unchanged into the resulting <file>.changes</file> file.
9791 <sect1 id="pkg-dpkg-genchanges">
9793 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9798 This program is usually called by package-independent
9799 automatic building scripts such as
9800 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9805 It is usually called in the top level of a built source
9806 tree, and when invoked with no arguments will print out a
9807 straightforward <file>.changes</file> file based on the
9808 information in the source package's changelog and control
9809 file and the binary and source packages which should have
9815 <sect1 id="pkg-dpkg-parsechangelog">
9817 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9818 representation of a changelog
9822 This program is used internally by
9823 <prgn>dpkg-source</prgn> et al. It may also occasionally
9824 be useful in <file>debian/rules</file> and elsewhere. It
9825 parses a changelog, <file>debian/changelog</file> by default,
9826 and prints a control-file format representation of the
9827 information in it to standard output.
9831 <sect1 id="pkg-dpkg-architecture">
9833 <prgn>dpkg-architecture</prgn> - information about the build and
9838 This program can be used manually, but is also invoked by
9839 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9840 environment or make variables which specify the build and host
9841 architecture for the package building process.
9846 <sect id="pkg-sourcetree">
9847 <heading>The Debianised source tree</heading>
9850 The source archive scheme described later is intended to
9851 allow a Debianised source tree with some associated control
9852 information to be reproduced and transported easily. The
9853 Debianised source tree is a version of the original program
9854 with certain files added for the benefit of the
9855 Debianisation process, and with any other changes required
9856 made to the rest of the source code and installation
9861 The extra files created for Debian are in the subdirectory
9862 <file>debian</file> of the top level of the Debianised source
9863 tree. They are described below.
9866 <sect1 id="pkg-debianrules">
9867 <heading><file>debian/rules</file> - the main building script</heading>
9870 See <ref id="debianrules">.
9875 <sect1 id="pkg-dpkgchangelog">
9876 <heading><file>debian/changelog</file></heading>
9879 See <ref id="dpkgchangelog">.
9882 <sect2><heading>Defining alternative changelog formats
9886 It is possible to use a different format to the standard
9887 one, by providing a parser for the format you wish to
9892 In order to have <tt>dpkg-parsechangelog</tt> run your
9893 parser, you must include a line within the last 40 lines
9894 of your file matching the Perl regular expression:
9895 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9896 parentheses should be the name of the format. For
9897 example, you might say:
9899 @@@ changelog-format: joebloggs @@@
9901 Changelog format names are non-empty strings of alphanumerics.
9905 If such a line exists then <tt>dpkg-parsechangelog</tt>
9906 will look for the parser as
9907 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9909 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9910 it is an error for it not to find it, or for it not to
9911 be an executable program. The default changelog format
9912 is <tt>dpkg</tt>, and a parser for it is provided with
9913 the <tt>dpkg</tt> package.
9917 The parser will be invoked with the changelog open on
9918 standard input at the start of the file. It should read
9919 the file (it may seek if it wishes) to determine the
9920 information required and return the parsed information
9921 to standard output in the form of a series of control
9922 fields in the standard format. By default it should
9923 return information about only the most recent version in
9924 the changelog; it should accept a
9925 <tt>-v<var>version</var></tt> option to return changes
9926 information from all versions present <em>strictly
9927 after</em> <var>version</var>, and it should then be an
9928 error for <var>version</var> not to be present in the
9934 <list compact="compact">
9935 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9936 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9937 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9938 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9939 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9940 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9941 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
9946 If several versions are being returned (due to the use
9947 of <tt>-v</tt>), the urgency value should be of the
9948 highest urgency code listed at the start of any of the
9949 versions requested followed by the concatenated
9950 (space-separated) comments from all the versions
9951 requested; the maintainer, version, distribution and
9952 date should always be from the most recent version.
9956 For the format of the <tt>Changes</tt> field see
9957 <ref id="f-Changes">.
9961 If the changelog format which is being parsed always or
9962 almost always leaves a blank line between individual
9963 change notes these blank lines should be stripped out,
9964 so as to make the resulting output compact.
9968 If the changelog format does not contain date or package
9969 name information this information should be omitted from
9970 the output. The parser should not attempt to synthesize
9971 it or find it from other sources.
9975 If the changelog does not have the expected format the
9976 parser should exit with a nonzero exit status, rather
9977 than trying to muddle through and possibly generating
9982 A changelog parser may not interact with the user at
9988 <sect1 id="pkg-srcsubstvars">
9989 <heading><file>debian/substvars</file> and variable substitutions</heading>
9992 See <ref id="substvars">.
9998 <heading><file>debian/files</file></heading>
10001 See <ref id="debianfiles">.
10005 <sect1><heading><file>debian/tmp</file>
10009 This is the canonical temporary location for the
10010 construction of binary packages by the <tt>binary</tt>
10011 target. The directory <file>tmp</file> serves as the root of
10012 the file system tree as it is being constructed (for
10013 example, by using the package's upstream makefiles install
10014 targets and redirecting the output there), and it also
10015 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10016 id="pkg-bincreating">.
10020 If several binary packages are generated from the same
10021 source tree it is usual to use several
10022 <file>debian/tmp<var>something</var></file> directories, for
10023 example <file>tmp-a</file> or <file>tmp-doc</file>.
10027 Whatever <file>tmp</file> directories are created and used by
10028 <tt>binary</tt> must of course be removed by the
10029 <tt>clean</tt> target.</p></sect1>
10033 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10037 As it exists on the FTP site, a Debian source package
10038 consists of three related files. You must have the right
10039 versions of all three to be able to use them.
10044 <tag>Debian source control file - <tt>.dsc</tt></tag>
10046 This file is a control file used by <prgn>dpkg-source</prgn>
10047 to extract a source package.
10048 See <ref id="debiansourcecontrolfiles">.
10052 Original source archive -
10054 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10060 This is a compressed (with <tt>gzip -9</tt>)
10061 <prgn>tar</prgn> file containing the source code from
10062 the upstream authors of the program.
10067 Debianisation diff -
10069 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10075 This is a unified context diff (<tt>diff -u</tt>)
10076 giving the changes which are required to turn the
10077 original source into the Debian source. These changes
10078 may only include editing and creating plain files.
10079 The permissions of files, the targets of symbolic
10080 links and the characteristics of special files or
10081 pipes may not be changed and no files may be removed
10086 All the directories in the diff must exist, except the
10087 <file>debian</file> subdirectory of the top of the source
10088 tree, which will be created by
10089 <prgn>dpkg-source</prgn> if necessary when unpacking.
10093 The <prgn>dpkg-source</prgn> program will
10094 automatically make the <file>debian/rules</file> file
10095 executable (see below).</p></item>
10100 If there is no original source code - for example, if the
10101 package is specially prepared for Debian or the Debian
10102 maintainer is the same as the upstream maintainer - the
10103 format is slightly different: then there is no diff, and the
10105 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10106 and preferably contains a directory named
10107 <file><var>package</var>-<var>version</var></file>.
10112 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10115 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10116 Debian source package. However, if it is not available it
10117 is possible to unpack a Debian source archive as follows:
10118 <enumlist compact="compact">
10121 Untar the tarfile, which will create a <file>.orig</file>
10125 <p>Rename the <file>.orig</file> directory to
10126 <file><var>package</var>-<var>version</var></file>.</p>
10130 Create the subdirectory <file>debian</file> at the top of
10131 the source tree.</p>
10133 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10135 <item><p>Untar the tarfile again if you want a copy of the original
10136 source code alongside the Debianised version.</p>
10141 It is not possible to generate a valid Debian source archive
10142 without using <prgn>dpkg-source</prgn>. In particular,
10143 attempting to use <prgn>diff</prgn> directly to generate the
10144 <file>.diff.gz</file> file will not work.
10148 <heading>Restrictions on objects in source packages</heading>
10151 The source package may not contain any hard links
10153 This is not currently detected when building source
10154 packages, but only when extracting
10158 Hard links may be permitted at some point in the
10159 future, but would require a fair amount of
10161 </footnote>, device special files, sockets or setuid or
10164 Setgid directories are allowed.
10169 The source packaging tools manage the changes between the
10170 original and Debianised source using <prgn>diff</prgn> and
10171 <prgn>patch</prgn>. Turning the original source tree as
10172 included in the <file>.orig.tar.gz</file> into the debianised
10173 source must not involve any changes which cannot be
10174 handled by these tools. Problematic changes which cause
10175 <prgn>dpkg-source</prgn> to halt with an error when
10176 building the source package are:
10177 <list compact="compact">
10178 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10180 <item><p>Changing the targets of symbolic links.</p>
10182 <item><p>Creating directories, other than <file>debian</file>.</p>
10184 <item><p>Changes to the contents of binary files.</p></item>
10185 </list> Changes which cause <prgn>dpkg-source</prgn> to
10186 print a warning but continue anyway are:
10187 <list compact="compact">
10190 Removing files, directories or symlinks.
10192 Renaming a file is not treated specially - it is
10193 seen as the removal of the old file (which
10194 generates a warning, but is otherwise ignored),
10195 and the creation of the new one.
10201 Changed text files which are missing the usual final
10202 newline (either in the original or the modified
10207 Changes which are not represented, but which are not detected by
10208 <prgn>dpkg-source</prgn>, are:
10209 <list compact="compact">
10210 <item><p>Changing the permissions of files (other than
10211 <file>debian/rules</file>) and directories.</p></item>
10216 The <file>debian</file> directory and <file>debian/rules</file>
10217 are handled specially by <prgn>dpkg-source</prgn> - before
10218 applying the changes it will create the <file>debian</file>
10219 directory, and afterwards it will make
10220 <file>debian/rules</file> world-executable.
10226 <appendix id="pkg-controlfields">
10227 <heading>Control files and their fields (from old Packaging Manual)</heading>
10230 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10231 data in a common format, known as control files. Binary and
10232 source packages have control data as do the <file>.changes</file>
10233 files which control the installation of uploaded files, and
10234 <prgn>dpkg</prgn>'s internal databases are in a similar
10239 <heading>Syntax of control files</heading>
10242 See <ref id="controlsyntax">.
10246 It is important to note that there are several fields which
10247 are optional as far as <prgn>dpkg</prgn> and the related
10248 tools are concerned, but which must appear in every Debian
10249 package, or whose omission may cause problems.
10254 <heading>List of fields</heading>
10257 See <ref id="controlfieldslist">.
10261 This section now contains only the fields that didn't belong
10262 to the Policy manual.
10265 <sect1 id="pkg-f-Filename">
10266 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10269 These fields in <tt>Packages</tt> files give the
10270 filename(s) of (the parts of) a package in the
10271 distribution directories, relative to the root of the
10272 Debian hierarchy. If the package has been split into
10273 several parts the parts are all listed in order, separated
10278 <sect1 id="pkg-f-Size">
10279 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10282 These fields in <file>Packages</file> files give the size (in
10283 bytes, expressed in decimal) and MD5 checksum of the
10284 file(s) which make(s) up a binary package in the
10285 distribution. If the package is split into several parts
10286 the values for the parts are listed in order, separated by
10291 <sect1 id="pkg-f-Status">
10292 <heading><tt>Status</tt></heading>
10295 This field in <prgn>dpkg</prgn>'s status file records
10296 whether the user wants a package installed, removed or
10297 left alone, whether it is broken (requiring
10298 re-installation) or not and what its current state on the
10299 system is. Each of these pieces of information is a
10304 <sect1 id="pkg-f-Config-Version">
10305 <heading><tt>Config-Version</tt></heading>
10308 If a package is not installed or not configured, this
10309 field in <prgn>dpkg</prgn>'s status file records the last
10310 version of the package which was successfully
10315 <sect1 id="pkg-f-Conffiles">
10316 <heading><tt>Conffiles</tt></heading>
10319 This field in <prgn>dpkg</prgn>'s status file contains
10320 information about the automatically-managed configuration
10321 files held by a package. This field should <em>not</em>
10322 appear anywhere in a package!
10327 <heading>Obsolete fields</heading>
10330 These are still recognized by <prgn>dpkg</prgn> but should
10331 not appear anywhere any more.
10333 <taglist compact="compact">
10335 <tag><tt>Revision</tt></tag>
10336 <tag><tt>Package-Revision</tt></tag>
10337 <tag><tt>Package_Revision</tt></tag>
10339 The Debian revision part of the package version was
10340 at one point in a separate control file field. This
10341 field went through several names.
10344 <tag><tt>Recommended</tt></tag>
10345 <item>Old name for <tt>Recommends</tt>.</item>
10347 <tag><tt>Optional</tt></tag>
10348 <item>Old name for <tt>Suggests</tt>.</item>
10350 <tag><tt>Class</tt></tag>
10351 <item>Old name for <tt>Priority</tt>.</item>
10360 <appendix id="pkg-conffiles">
10361 <heading>Configuration file handling (from old Packaging Manual)</heading>
10364 <prgn>dpkg</prgn> can do a certain amount of automatic
10365 handling of package configuration files.
10369 Whether this mechanism is appropriate depends on a number of
10370 factors, but basically there are two approaches to any
10371 particular configuration file.
10375 The easy method is to ship a best-effort configuration in the
10376 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10377 handle updates. If the user is unlikely to want to edit the
10378 file, but you need them to be able to without losing their
10379 changes, and a new package with a changed version of the file
10380 is only released infrequently, this is a good approach.
10384 The hard method is to build the configuration file from
10385 scratch in the <prgn>postinst</prgn> script, and to take the
10386 responsibility for fixing any mistakes made in earlier
10387 versions of the package automatically. This will be
10388 appropriate if the file is likely to need to be different on
10392 <sect><heading>Automatic handling of configuration files by
10397 A package may contain a control area file called
10398 <tt>conffiles</tt>. This file should be a list of filenames
10399 of configuration files needing automatic handling, separated
10400 by newlines. The filenames should be absolute pathnames,
10401 and the files referred to should actually exist in the
10406 When a package is upgraded <prgn>dpkg</prgn> will process
10407 the configuration files during the configuration stage,
10408 shortly before it runs the package's <prgn>postinst</prgn>
10413 For each file it checks to see whether the version of the
10414 file included in the package is the same as the one that was
10415 included in the last version of the package (the one that is
10416 being upgraded from); it also compares the version currently
10417 installed on the system with the one shipped with the last
10422 If neither the user nor the package maintainer has changed
10423 the file, it is left alone. If one or the other has changed
10424 their version, then the changed version is preferred - i.e.,
10425 if the user edits their file, but the package maintainer
10426 doesn't ship a different version, the user's changes will
10427 stay, silently, but if the maintainer ships a new version
10428 and the user hasn't edited it the new version will be
10429 installed (with an informative message). If both have
10430 changed their version the user is prompted about the problem
10431 and must resolve the differences themselves.
10435 The comparisons are done by calculating the MD5 message
10436 digests of the files, and storing the MD5 of the file as it
10437 was included in the most recent version of the package.
10441 When a package is installed for the first time
10442 <prgn>dpkg</prgn> will install the file that comes with it,
10443 unless that would mean overwriting a file already on the
10448 However, note that <prgn>dpkg</prgn> will <em>not</em>
10449 replace a conffile that was removed by the user (or by a
10450 script). This is necessary because with some programs a
10451 missing file produces an effect hard or impossible to
10452 achieve in another way, so that a missing file needs to be
10453 kept that way if the user did it.
10457 Note that a package should <em>not</em> modify a
10458 <prgn>dpkg</prgn>-handled conffile in its maintainer
10459 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10460 the user confusing and possibly dangerous options for
10461 conffile update when the package is upgraded.</p>
10464 <sect><heading>Fully-featured maintainer script configuration
10469 For files which contain site-specific information such as
10470 the hostname and networking details and so forth, it is
10471 better to create the file in the package's
10472 <prgn>postinst</prgn> script.
10476 This will typically involve examining the state of the rest
10477 of the system to determine values and other information, and
10478 may involve prompting the user for some information which
10479 can't be obtained some other way.
10483 When using this method there are a couple of important
10484 issues which should be considered:
10488 If you discover a bug in the program which generates the
10489 configuration file, or if the format of the file changes
10490 from one version to the next, you will have to arrange for
10491 the postinst script to do something sensible - usually this
10492 will mean editing the installed configuration file to remove
10493 the problem or change the syntax. You will have to do this
10494 very carefully, since the user may have changed the file,
10495 perhaps to fix the very problem that your script is trying
10496 to deal with - you will have to detect these situations and
10497 deal with them correctly.
10501 If you do go down this route it's probably a good idea to
10502 make the program that generates the configuration file(s) a
10503 separate program in <file>/usr/sbin</file>, by convention called
10504 <file><var>package</var>config</file> and then run that if
10505 appropriate from the post-installation script. The
10506 <tt><var>package</var>config</tt> program should not
10507 unquestioningly overwrite an existing configuration - if its
10508 mode of operation is geared towards setting up a package for
10509 the first time (rather than any arbitrary reconfiguration
10510 later) you should have it check whether the configuration
10511 already exists, and require a <tt>--force</tt> flag to
10512 overwrite it.</p></sect>
10515 <appendix id="pkg-alternatives"><heading>Alternative versions of
10516 an interface - <prgn>update-alternatives</prgn> (from old
10521 When several packages all provide different versions of the
10522 same program or file it is useful to have the system select a
10523 default, but to allow the system administrator to change it
10524 and have their decisions respected.
10528 For example, there are several versions of the <prgn>vi</prgn>
10529 editor, and there is no reason to prevent all of them from
10530 being installed at once, each under their own name
10531 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10532 Nevertheless it is desirable to have the name <tt>vi</tt>
10533 refer to something, at least by default.
10537 If all the packages involved cooperate, this can be done with
10538 <prgn>update-alternatives</prgn>.
10542 Each package provides its own version under its own name, and
10543 calls <prgn>update-alternatives</prgn> in its postinst to
10544 register its version (and again in its prerm to deregister
10549 See the man page <manref name="update-alternatives"
10550 section="8"> for details.
10554 If <prgn>update-alternatives</prgn> does not seem appropriate
10555 you may wish to consider using diversions instead.</p>
10558 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10559 package's version of a file (from old Packaging Manual)
10563 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10564 when it reinstalls the package it belongs to, and to have it
10565 put the file from the package somewhere else instead.
10569 This can be used locally to override a package's version of a
10570 file, or by one package to override another's version (or
10571 provide a wrapper for it).
10575 Before deciding to use a diversion, read <ref
10576 id="pkg-alternatives"> to see if you really want a diversion
10577 rather than several alternative versions of a program.
10581 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10582 and updated by a special program <prgn>dpkg-divert</prgn>.
10583 Please see <manref name="dpkg-divert" section="8"> for full
10584 details of its operation.
10588 When a package wishes to divert a file from another, it should
10589 call <prgn>dpkg-divert</prgn> in its preinst to add the
10590 diversion and rename the existing file. For example,
10591 supposing that a <prgn>smailwrapper</prgn> package wishes to
10592 install a wrapper around <file>/usr/sbin/smail</file>:
10594 dpkg-divert --package smailwrapper --add --rename \
10595 --divert /usr/sbin/smail.real /usr/sbin/smail
10596 </example> The <tt>--package smailwrapper</tt> ensures that
10597 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10598 can bypass the diversion and get installed as the true version.
10599 It's safe to add the diversion unconditionally on upgrades since
10600 it will be left unchanged if it already exists, but
10601 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10602 message, make the command conditional on the version from which
10603 the package is being upgraded:
10605 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10606 dpkg-divert --package smailwrapper --add --rename \
10607 --divert /usr/sbin/smail.real /usr/sbin/smail
10609 </example> where <tt>1.0-2</tt> is the version at which the
10610 diversion was first added to the package. Running the command
10611 during abort-upgrade is pointless but harmless.
10615 The postrm has to do the reverse:
10617 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10618 dpkg-divert --package smailwrapper --remove --rename \
10619 --divert /usr/sbin/smail.real /usr/sbin/smail
10621 </example> If the diversion was added at a particular version, the
10622 postrm should also handle the failure case of upgrading from an
10623 older version (unless the older version is so old that direct
10624 upgrades are no longer supported):
10626 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10627 dpkg-divert --package smailwrapper --remove --rename \
10628 --divert /usr/sbin/smail.real /usr/sbin/smail
10630 </example> where <tt>1.02-2</tt> is the version at which the
10631 diversion was first added to the package. The postrm should not
10632 remove the diversion on upgrades both because there's no reason to
10633 remove the diversion only to immediately re-add it and since the
10634 postrm of the old package is run after unpacking so the removal of
10635 the diversion will fail.
10639 Do not attempt to divert a file which is vitally important for
10640 the system's operation - when using <prgn>dpkg-divert</prgn>
10641 there is a time, after it has been diverted but before
10642 <prgn>dpkg</prgn> has installed the new version, when the file
10643 does not exist.</p>
10648 <!-- Local variables: -->
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