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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 interface not changing, and the package management
94 software authors need to ensure compatibility with
95 this interface definition. (Control file and
96 changelog file formats are examples.)
98 <tag>Chosen Convention</tag>
100 If there are a number of technically viable choices
101 that can be made, but one needs to select one of
102 these options for inter-operability. The version
103 number format is one example.
106 Please note that these are not mutually exclusive;
107 selected conventions often become parts of standard
113 The footnotes present in this manual are
114 merely informative, and are not part of Debian policy itself.
118 The appendices to this manual are not necessarily normative,
119 either. Please see <ref id="pkg-scope"> for more information.
123 In the normative part of this manual,
124 the words <em>must</em>, <em>should</em> and
125 <em>may</em>, and the adjectives <em>required</em>,
126 <em>recommended</em> and <em>optional</em>, are used to
127 distinguish the significance of the various guidelines in
128 this policy document. Packages that do not conform to the
129 guidelines denoted by <em>must</em> (or <em>required</em>)
130 will generally not be considered acceptable for the Debian
131 distribution. Non-conformance with guidelines denoted by
132 <em>should</em> (or <em>recommended</em>) will generally be
133 considered a bug, but will not necessarily render a package
134 unsuitable for distribution. Guidelines denoted by
135 <em>may</em> (or <em>optional</em>) are truly optional and
136 adherence is left to the maintainer's discretion.
140 These classifications are roughly equivalent to the bug
141 severities <em>serious</em> (for <em>must</em> or
142 <em>required</em> directive violations), <em>minor</em>,
143 <em>normal</em> or <em>important</em>
144 (for <em>should</em> or <em>recommended</em> directive
145 violations) and <em>wishlist</em> (for <em>optional</em>
148 Compare RFC 2119. Note, however, that these words are
149 used in a different way in this document.
154 Much of the information presented in this manual will be
155 useful even when building a package which is to be
156 distributed in some other way or is intended for local use
162 <heading>New versions of this document</heading>
165 This manual is distributed via the Debian package
166 <package><url name="debian-policy"
167 id="http://packages.debian.org/debian-policy"></package>
168 (<httpsite>packages.debian.org</httpsite>
169 <httppath>/debian-policy</httppath>).
173 The current version of this document is also available from
174 the Debian web mirrors at
175 <tt><url name="/doc/debian-policy/"
176 id="http://www.debian.org/doc/debian-policy/"></tt>.
178 <httpsite>www.debian.org</httpsite>
179 <httppath>/doc/debian-policy/</httppath>)
180 Also available from the same directory are several other
181 formats: <file>policy.html.tar.gz</file>
182 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
183 <file>policy.pdf.gz</file>
184 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
185 and <file>policy.ps.gz</file>
186 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
190 The <package>debian-policy</package> package also includes the file
191 <file>upgrading-checklist.txt.gz</file> which indicates policy
192 changes between versions of this document.
197 <heading>Authors and Maintainers</heading>
200 Originally called "Debian GNU/Linux Policy Manual", this
201 manual was initially written in 1996 by Ian Jackson.
202 It was revised on November 27th, 1996 by David A. Morris.
203 Christian Schwarz added new sections on March 15th, 1997,
204 and reworked/restructured it in April-July 1997.
205 Christoph Lameter contributed the "Web Standard".
206 Julian Gilbey largely restructured it in 2001.
210 Since September 1998, the responsibility for the contents of
211 this document lies on the <url name="debian-policy mailing list"
212 id="mailto:debian-policy@lists.debian.org">. Proposals
213 are discussed there and inserted into policy after a certain
214 consensus is established.
215 <!-- insert shameless policy-process plug here eventually -->
216 The actual editing is done by a group of maintainers that have
217 no editorial powers. These are the current maintainers:
220 <item>Julian Gilbey</item>
221 <item>Branden Robinson</item>
222 <item>Josip Rodin</item>
223 <item>Manoj Srivastava</item>
228 While the authors of this document have tried hard to avoid
229 typos and other errors, these do still occur. If you discover
230 an error in this manual or if you want to give any
231 comments, suggestions, or criticisms please send an email to
232 the Debian Policy List,
233 <email>debian-policy@lists.debian.org</email>, or submit a
234 bug report against the <tt>debian-policy</tt> package.
238 Please do not try to reach the individual authors or maintainers
239 of the Policy Manual regarding changes to the Policy.
244 <heading>Related documents</heading>
247 There are several other documents other than this Policy Manual
248 that are necessary to fully understand some Debian policies and
253 The external "sub-policy" documents are referred to in:
254 <list compact="compact">
255 <item><ref id="fhs"></item>
256 <item><ref id="virtual_pkg"></item>
257 <item><ref id="menus"></item>
258 <item><ref id="mime"></item>
259 <item><ref id="perl"></item>
260 <item><ref id="maintscriptprompt"></item>
261 <item><ref id="emacs"></item>
266 In addition to those, which carry the weight of policy, there
267 is the Debian Developer's Reference. This document describes
268 procedures and resources for Debian developers, but it is
269 <em>not</em> normative; rather, it includes things that don't
270 belong in the Policy, such as best practices for developers.
274 The Developer's Reference is available in the
275 <package>developers-reference</package> package.
276 It's also available from the Debian web mirrors at
277 <tt><url name="/doc/developers-reference/"
278 id="http://www.debian.org/doc/developers-reference/"></tt>.
282 <sect id="definitions">
283 <heading>Definitions</heading>
286 The following terms are used in this Policy Manual:
290 The character encoding specified by ANSI X3.4-1986 and its
291 predecessor standards, referred to in MIME as US-ASCII, and
292 corresponding to an encoding in eight bits per character of
293 the first 128 <url id="http://www.unicode.org/"
294 name="Unicode"> characters, with the eighth bit always zero.
298 The transformation format (sometimes called encoding) of
299 <url id="http://www.unicode.org/" name="Unicode"> defined by
300 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
301 name="RFC 3629">. UTF-8 has the useful property of having
302 ASCII as a subset, so any text encoded in ASCII is trivially
312 <heading>The Debian Archive</heading>
315 The Debian GNU/Linux system is maintained and distributed as a
316 collection of <em>packages</em>. Since there are so many of
317 them (currently well over 15000), they are split into
318 <em>sections</em> and given <em>priorities</em> to simplify
319 the handling of them.
323 The effort of the Debian project is to build a free operating
324 system, but not every package we want to make accessible is
325 <em>free</em> in our sense (see the Debian Free Software
326 Guidelines, below), or may be imported/exported without
327 restrictions. Thus, the archive is split into areas<footnote>
328 The Debian archive software uses the term "component" internally
329 and in the Release file format to refer to the division of an
330 archive. The Debian Social Contract simply refers to "areas."
331 This document uses terminology similar to the Social Contract.
332 </footnote> based on their licenses and other restrictions.
336 The aims of this are:
338 <list compact="compact">
339 <item>to allow us to make as much software available as we can</item>
340 <item>to allow us to encourage everyone to write free software,
342 <item>to allow us to make it easy for people to produce
343 CD-ROMs of our system without violating any licenses,
344 import/export restrictions, or any other laws.</item>
349 The <em>main</em> archive area forms the <em>Debian GNU/Linux
354 Packages in the other archive areas (<tt>contrib</tt>,
355 <tt>non-free</tt>) are not considered to be part of the Debian
356 distribution, although we support their use and provide
357 infrastructure for them (such as our bug-tracking system and
358 mailing lists). This Debian Policy Manual applies to these
363 <heading>The Debian Free Software Guidelines</heading>
365 The Debian Free Software Guidelines (DFSG) form our
366 definition of "free software". These are:
368 <tag>1. Free Redistribution
371 The license of a Debian component may not restrict any
372 party from selling or giving away the software as a
373 component of an aggregate software distribution
374 containing programs from several different
375 sources. The license may not require a royalty or
376 other fee for such sale.
381 The program must include source code, and must allow
382 distribution in source code as well as compiled form.
384 <tag>3. Derived Works
387 The license must allow modifications and derived
388 works, and must allow them to be distributed under the
389 same terms as the license of the original software.
391 <tag>4. Integrity of The Author's Source Code
394 The license may restrict source-code from being
395 distributed in modified form <em>only</em> if the
396 license allows the distribution of "patch files"
397 with the source code for the purpose of modifying the
398 program at build time. The license must explicitly
399 permit distribution of software built from modified
400 source code. The license may require derived works to
401 carry a different name or version number from the
402 original software. (This is a compromise. The Debian
403 Project encourages all authors to not restrict any
404 files, source or binary, from being modified.)
406 <tag>5. No Discrimination Against Persons or Groups
409 The license must not discriminate against any person
412 <tag>6. No Discrimination Against Fields of Endeavor
415 The license must not restrict anyone from making use
416 of the program in a specific field of endeavor. For
417 example, it may not restrict the program from being
418 used in a business, or from being used for genetic
421 <tag>7. Distribution of License
424 The rights attached to the program must apply to all
425 to whom the program is redistributed without the need
426 for execution of an additional license by those
429 <tag>8. License Must Not Be Specific to Debian
432 The rights attached to the program must not depend on
433 the program's being part of a Debian system. If the
434 program is extracted from Debian and used or
435 distributed without Debian but otherwise within the
436 terms of the program's license, all parties to whom
437 the program is redistributed must have the same
438 rights as those that are granted in conjunction with
441 <tag>9. License Must Not Contaminate Other Software
444 The license must not place restrictions on other
445 software that is distributed along with the licensed
446 software. For example, the license must not insist
447 that all other programs distributed on the same medium
448 must be free software.
450 <tag>10. Example Licenses
453 The "GPL," "BSD," and "Artistic" licenses are examples of
454 licenses that we consider <em>free</em>.
461 <heading>Archive areas</heading>
464 <heading>The main archive area</heading>
467 Every package in <em>main</em> must comply with the DFSG
468 (Debian Free Software Guidelines).
472 In addition, the packages in <em>main</em>
473 <list compact="compact">
475 must not require a package outside of <em>main</em>
476 for compilation or execution (thus, the package must
477 not declare a "Depends", "Recommends", or
478 "Build-Depends" relationship on a non-<em>main</em>
482 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
495 <heading>The contrib archive area</heading>
498 Every package in <em>contrib</em> must comply with the DFSG.
502 In addition, the packages in <em>contrib</em>
503 <list compact="compact">
505 must not be so buggy that we refuse to support them,
509 must meet all policy requirements presented in this
517 Examples of packages which would be included in
518 <em>contrib</em> are:
519 <list compact="compact">
521 free packages which require <em>contrib</em>,
522 <em>non-free</em> packages or packages which are not
523 in our archive at all for compilation or execution,
527 wrapper packages or other sorts of free accessories for
534 <sect1 id="non-free">
535 <heading>The non-free archive area</heading>
538 Packages must be placed in <em>non-free</em> if they are
539 not compliant with the DFSG or are encumbered by patents
540 or other legal issues that make their distribution
545 In addition, the packages in <em>non-free</em>
546 <list compact="compact">
548 must not be so buggy that we refuse to support them,
552 must meet all policy requirements presented in this
553 manual that it is possible for them to meet.
555 It is possible that there are policy
556 requirements which the package is unable to
557 meet, for example, if the source is
558 unavailable. These situations will need to be
559 handled on a case-by-case basis.
568 <sect id="pkgcopyright">
569 <heading>Copyright considerations</heading>
572 Every package must be accompanied by a verbatim copy of
573 its copyright and distribution license in the file
574 <file>/usr/share/doc/<var>package</var>/copyright</file>
575 (see <ref id="copyrightfile"> for further details).
579 We reserve the right to restrict files from being included
580 anywhere in our archives if
581 <list compact="compact">
583 their use or distribution would break a law,
586 there is an ethical conflict in their distribution or
590 we would have to sign a license for them, or
593 their distribution would conflict with other project
600 Programs whose authors encourage the user to make
601 donations are fine for the main distribution, provided
602 that the authors do not claim that not donating is
603 immoral, unethical, illegal or something similar; in such
604 a case they must go in <em>non-free</em>.
608 Packages whose copyright permission notices (or patent
609 problems) do not even allow redistribution of binaries
610 only, and where no special permission has been obtained,
611 must not be placed on the Debian FTP site and its mirrors
616 Note that under international copyright law (this applies
617 in the United States, too), <em>no</em> distribution or
618 modification of a work is allowed without an explicit
619 notice saying so. Therefore a program without a copyright
620 notice <em>is</em> copyrighted and you may not do anything
621 to it without risking being sued! Likewise if a program
622 has a copyright notice but no statement saying what is
623 permitted then nothing is permitted.
627 Many authors are unaware of the problems that restrictive
628 copyrights (or lack of copyright notices) can cause for
629 the users of their supposedly-free software. It is often
630 worthwhile contacting such authors diplomatically to ask
631 them to modify their license terms. However, this can be a
632 politically difficult thing to do and you should ask for
633 advice on the <tt>debian-legal</tt> mailing list first, as
638 When in doubt about a copyright, send mail to
639 <email>debian-legal@lists.debian.org</email>. Be prepared
640 to provide us with the copyright statement. Software
641 covered by the GPL, public domain software and BSD-like
642 copyrights are safe; be wary of the phrases "commercial
643 use prohibited" and "distribution restricted".
647 <sect id="subsections">
648 <heading>Sections</heading>
651 The packages in the archive areas <em>main</em>,
652 <em>contrib</em> and <em>non-free</em> are grouped further into
653 <em>sections</em> to simplify handling.
657 The archive area and section for each package should be
658 specified in the package's <tt>Section</tt> control record (see
659 <ref id="f-Section">). However, the maintainer of the Debian
660 archive may override this selection to ensure the consistency of
661 the Debian distribution. The <tt>Section</tt> field should be
663 <list compact="compact">
665 <em>section</em> if the package is in the
666 <em>main</em> archive area,
669 <em>area/section</em> if the package is in
670 the <em>contrib</em> or <em>non-free</em>
677 The Debian archive maintainers provide the authoritative
678 list of sections. At present, they are:
679 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
680 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
681 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
682 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
683 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
684 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
685 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
686 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
687 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
688 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
689 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
690 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
691 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
696 <sect id="priorities">
697 <heading>Priorities</heading>
700 Each package should have a <em>priority</em> value, which is
701 included in the package's <em>control record</em>
702 (see <ref id="f-Priority">).
703 This information is used by the Debian package management tools to
704 separate high-priority packages from less-important packages.
708 The following <em>priority levels</em> are recognized by the
709 Debian package management tools.
711 <tag><tt>required</tt></tag>
713 Packages which are necessary for the proper
714 functioning of the system (usually, this means that
715 dpkg functionality depends on these packages).
716 Removing a <tt>required</tt> package may cause your
717 system to become totally broken and you may not even
718 be able to use <prgn>dpkg</prgn> to put things back,
719 so only do so if you know what you are doing. Systems
720 with only the <tt>required</tt> packages are probably
721 unusable, but they do have enough functionality to
722 allow the sysadmin to boot and install more software.
724 <tag><tt>important</tt></tag>
726 Important programs, including those which one would
727 expect to find on any Unix-like system. If the
728 expectation is that an experienced Unix person who
729 found it missing would say "What on earth is going on,
730 where is <prgn>foo</prgn>?", it must be an
731 <tt>important</tt> package.<footnote>
732 This is an important criterion because we are
733 trying to produce, amongst other things, a free
736 Other packages without which the system will not run
737 well or be usable must also have priority
738 <tt>important</tt>. This does
739 <em>not</em> include Emacs, the X Window System, TeX
740 or any other large applications. The
741 <tt>important</tt> packages are just a bare minimum of
742 commonly-expected and necessary tools.
744 <tag><tt>standard</tt></tag>
746 These packages provide a reasonably small but not too
747 limited character-mode system. This is what will be
748 installed by default if the user doesn't select anything
749 else. It doesn't include many large applications.
751 <tag><tt>optional</tt></tag>
753 (In a sense everything that isn't required is
754 optional, but that's not what is meant here.) This is
755 all the software that you might reasonably want to
756 install if you didn't know what it was and don't have
757 specialized requirements. This is a much larger system
758 and includes the X Window System, a full TeX
759 distribution, and many applications. Note that
760 optional packages should not conflict with each other.
762 <tag><tt>extra</tt></tag>
764 This contains all packages that conflict with others
765 with required, important, standard or optional
766 priorities, or are only likely to be useful if you
767 already know what they are or have specialized
768 requirements (such as packages containing only detached
775 Packages must not depend on packages with lower priority
776 values (excluding build-time dependencies). In order to
777 ensure this, the priorities of one or more packages may need
786 <heading>Binary packages</heading>
789 The Debian GNU/Linux distribution is based on the Debian
790 package management system, called <prgn>dpkg</prgn>. Thus,
791 all packages in the Debian distribution must be provided
792 in the <tt>.deb</tt> file format.
796 <heading>The package name</heading>
799 Every package must have a name that's unique within the Debian
804 The package name is included in the control field
805 <tt>Package</tt>, the format of which is described
806 in <ref id="f-Package">.
807 The package name is also included as a part of the file name
808 of the <tt>.deb</tt> file.
813 <heading>The version of a package</heading>
816 Every package has a version number recorded in its
817 <tt>Version</tt> control file field, described in
818 <ref id="f-Version">.
822 The package management system imposes an ordering on version
823 numbers, so that it can tell whether packages are being up- or
824 downgraded and so that package system front end applications
825 can tell whether a package it finds available is newer than
826 the one installed on the system. The version number format
827 has the most significant parts (as far as comparison is
828 concerned) at the beginning.
832 If an upstream package has problematic version numbers they
833 should be converted to a sane form for use in the
834 <tt>Version</tt> field.
838 <heading>Version numbers based on dates</heading>
841 In general, Debian packages should use the same version
842 numbers as the upstream sources.
846 However, in some cases where the upstream version number is
847 based on a date (e.g., a development "snapshot" release) the
848 package management system cannot handle these version
849 numbers without epochs. For example, dpkg will consider
850 "96May01" to be greater than "96Dec24".
854 To prevent having to use epochs for every new upstream
855 version, the date based portion of the version number
856 should be changed to the following format in such cases:
857 "19960501", "19961224". It is up to the maintainer whether
858 they want to bother the upstream maintainer to change
859 the version numbers upstream, too.
863 Note that other version formats based on dates which are
864 parsed correctly by the package management system should
865 <em>not</em> be changed.
869 Native Debian packages (i.e., packages which have been
870 written especially for Debian) whose version numbers include
871 dates should always use the "YYYYMMDD" format.
878 <heading>The maintainer of a package</heading>
881 Every package must have a Debian maintainer (the
882 maintainer may be one person or a group of people
883 reachable from a common email address, such as a mailing
884 list). The maintainer is responsible for ensuring that
885 the package is placed in the appropriate distributions.
889 The maintainer must be specified in the
890 <tt>Maintainer</tt> control field with their correct name
891 and a working email address. If one person maintains
892 several packages, they should try to avoid having
893 different forms of their name and email address in
894 the <tt>Maintainer</tt> fields of those packages.
898 The format of the <tt>Maintainer</tt> control field is
899 described in <ref id="f-Maintainer">.
903 If the maintainer of a package quits from the Debian
904 project, "Debian QA Group"
905 <email>packages@qa.debian.org</email> takes over the
906 maintainer-ship of the package until someone else
907 volunteers for that task. These packages are called
908 <em>orphaned packages</em>.<footnote>
909 The detailed procedure for doing this gracefully can
910 be found in the Debian Developer's Reference,
911 see <ref id="related">.
916 <sect id="descriptions">
917 <heading>The description of a package</heading>
920 Every Debian package must have an extended description
921 stored in the appropriate field of the control record.
922 The technical information about the format of the
923 <tt>Description</tt> field is in <ref id="f-Description">.
927 The description should describe the package (the program) to a
928 user (system administrator) who has never met it before so that
929 they have enough information to decide whether they want to
930 install it. This description should not just be copied verbatim
931 from the program's documentation.
935 Put important information first, both in the synopsis and
936 extended description. Sometimes only the first part of the
937 synopsis or of the description will be displayed. You can
938 assume that there will usually be a way to see the whole
939 extended description.
943 The description should also give information about the
944 significant dependencies and conflicts between this package
945 and others, so that the user knows why these dependencies and
946 conflicts have been declared.
950 Instructions for configuring or using the package should
951 not be included (that is what installation scripts,
952 manual pages, info files, etc., are for). Copyright
953 statements and other administrivia should not be included
954 either (that is what the copyright file is for).
957 <sect1 id="synopsis"><heading>The single line synopsis</heading>
960 The single line synopsis should be kept brief - certainly
965 Do not include the package name in the synopsis line. The
966 display software knows how to display this already, and you
967 do not need to state it. Remember that in many situations
968 the user may only see the synopsis line - make it as
969 informative as you can.
974 <sect1 id="extendeddesc"><heading>The extended description</heading>
977 Do not try to continue the single line synopsis into the
978 extended description. This will not work correctly when
979 the full description is displayed, and makes no sense
980 where only the summary (the single line synopsis) is
985 The extended description should describe what the package
986 does and how it relates to the rest of the system (in terms
987 of, for example, which subsystem it is which part of).
991 The description field needs to make sense to anyone, even
992 people who have no idea about any of the things the
993 package deals with.<footnote>
994 The blurb that comes with a program in its
995 announcements and/or <prgn>README</prgn> files is
996 rarely suitable for use in a description. It is
997 usually aimed at people who are already in the
998 community where the package is used.
1007 <heading>Dependencies</heading>
1010 Every package must specify the dependency information
1011 about other packages that are required for the first to
1016 For example, a dependency entry must be provided for any
1017 shared libraries required by a dynamically-linked executable
1018 binary in a package.
1022 Packages are not required to declare any dependencies they
1023 have on other packages which are marked <tt>Essential</tt>
1024 (see below), and should not do so unless they depend on a
1025 particular version of that package.<footnote>
1027 Essential is needed in part to avoid unresolvable dependency
1028 loops on upgrade. If packages add unnecessary dependencies
1029 on packages in this set, the chances that there
1030 <strong>will</strong> be an unresolvable dependency loop
1031 caused by forcing these Essential packages to be configured
1032 first before they need to be is greatly increased. It also
1033 increases the chances that frontends will be unable to
1034 <strong>calculate</strong> an upgrade path, even if one
1038 Also, functionality is rarely ever removed from the
1039 Essential set, but <em>packages</em> have been removed from
1040 the Essential set when the functionality moved to a
1041 different package. So depending on these packages <em>just
1042 in case</em> they stop being essential does way more harm
1049 Sometimes, a package requires another package to be installed
1050 <em>and</em> configured before it can be installed. In this
1051 case, you must specify a <tt>Pre-Depends</tt> entry for
1056 You should not specify a <tt>Pre-Depends</tt> entry for a
1057 package before this has been discussed on the
1058 <tt>debian-devel</tt> mailing list and a consensus about
1059 doing that has been reached.
1063 The format of the package interrelationship control fields is
1064 described in <ref id="relationships">.
1068 <sect id="virtual_pkg">
1069 <heading>Virtual packages</heading>
1072 Sometimes, there are several packages which offer
1073 more-or-less the same functionality. In this case, it's
1074 useful to define a <em>virtual package</em> whose name
1075 describes that common functionality. (The virtual
1076 packages only exist logically, not physically; that's why
1077 they are called <em>virtual</em>.) The packages with this
1078 particular function will then <em>provide</em> the virtual
1079 package. Thus, any other package requiring that function
1080 can simply depend on the virtual package without having to
1081 specify all possible packages individually.
1085 All packages should use virtual package names where
1086 appropriate, and arrange to create new ones if necessary.
1087 They should not use virtual package names (except privately,
1088 amongst a cooperating group of packages) unless they have
1089 been agreed upon and appear in the list of virtual package
1090 names. (See also <ref id="virtual">)
1094 The latest version of the authoritative list of virtual
1095 package names can be found in the <tt>debian-policy</tt> package.
1096 It is also available from the Debian web mirrors at
1097 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1098 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1102 The procedure for updating the list is described in the preface
1109 <heading>Base system</heading>
1112 The <tt>base system</tt> is a minimum subset of the Debian
1113 GNU/Linux system that is installed before everything else
1114 on a new system. Only very few packages are allowed to form
1115 part of the base system, in order to keep the required disk
1120 The base system consists of all those packages with priority
1121 <tt>required</tt> or <tt>important</tt>. Many of them will
1122 be tagged <tt>essential</tt> (see below).
1127 <heading>Essential packages</heading>
1130 Essential is defined as the minimal set of functionality that
1131 must be available and usable on the system at all times, even
1132 when packages are in an unconfigured (but unpacked) state.
1133 Packages are tagged <tt>essential</tt> for a system using the
1134 <tt>Essential</tt> control file field. The format of the
1135 <tt>Essential</tt> control field is described in <ref
1140 Since these packages cannot be easily removed (one has to
1141 specify an extra <em>force option</em> to
1142 <prgn>dpkg</prgn> to do so), this flag must not be used
1143 unless absolutely necessary. A shared library package
1144 must not be tagged <tt>essential</tt>; dependencies will
1145 prevent its premature removal, and we need to be able to
1146 remove it when it has been superseded.
1150 Since dpkg will not prevent upgrading of other packages
1151 while an <tt>essential</tt> package is in an unconfigured
1152 state, all <tt>essential</tt> packages must supply all of
1153 their core functionality even when unconfigured. If the
1154 package cannot satisfy this requirement it must not be
1155 tagged as essential, and any packages depending on this
1156 package must instead have explicit dependency fields as
1161 Maintainers should take great care in adding any programs,
1162 interfaces, or functionality to <tt>essential</tt> packages.
1163 Packages may assume that functionality provided by
1164 <tt>essential</tt> packages is always available without
1165 declaring explicit dependencies, which means that removing
1166 functionality from the Essential set is very difficult and is
1167 almost never done. Any capability added to an
1168 <tt>essential</tt> package therefore creates an obligation to
1169 support that capability as part of the Essential set in
1174 You must not tag any packages <tt>essential</tt> before
1175 this has been discussed on the <tt>debian-devel</tt>
1176 mailing list and a consensus about doing that has been
1181 <sect id="maintscripts">
1182 <heading>Maintainer Scripts</heading>
1185 The package installation scripts should avoid producing
1186 output which is unnecessary for the user to see and
1187 should rely on <prgn>dpkg</prgn> to stave off boredom on
1188 the part of a user installing many packages. This means,
1189 amongst other things, using the <tt>--quiet</tt> option on
1190 <prgn>install-info</prgn>.
1194 Errors which occur during the execution of an installation
1195 script must be checked and the installation must not
1196 continue after an error.
1200 Note that in general <ref id="scripts"> applies to package
1201 maintainer scripts, too.
1205 You should not use <prgn>dpkg-divert</prgn> on a file
1206 belonging to another package without consulting the
1207 maintainer of that package first.
1211 All packages which supply an instance of a common command
1212 name (or, in general, filename) should generally use
1213 <prgn>update-alternatives</prgn>, so that they may be
1214 installed together. If <prgn>update-alternatives</prgn>
1215 is not used, then each package must use
1216 <tt>Conflicts</tt> to ensure that other packages are
1217 de-installed. (In this case, it may be appropriate to
1218 specify a conflict against earlier versions of something
1219 that previously did not use
1220 <prgn>update-alternatives</prgn>; this is an exception to
1221 the usual rule that versioned conflicts should be
1225 <sect1 id="maintscriptprompt">
1226 <heading>Prompting in maintainer scripts</heading>
1228 Package maintainer scripts may prompt the user if
1229 necessary. Prompting must be done by communicating
1230 through a program, such as <prgn>debconf</prgn>, which
1231 conforms to the Debian Configuration Management
1232 Specification, version 2 or higher.
1236 Packages which are essential, or which are dependencies of
1237 essential packages, may fall back on another prompting method
1238 if no such interface is available when they are executed.
1242 The Debian Configuration Management Specification is included
1243 in the <file>debconf_specification</file> files in the
1244 <package>debian-policy</package> package.
1245 It is also available from the Debian web mirrors at
1246 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1247 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1251 Packages which use the Debian Configuration Management
1252 Specification may contain an additional
1253 <prgn>config</prgn> script and a <tt>templates</tt>
1254 file in their control archive<footnote>
1255 The control.tar.gz inside the .deb.
1256 See <manref name="deb" section="5">.
1258 The <prgn>config</prgn> script might be run before the
1259 <prgn>preinst</prgn> script, and before the package is unpacked
1260 or any of its dependencies or pre-dependencies are satisfied.
1261 Therefore it must work using only the tools present in
1262 <em>essential</em> packages.<footnote>
1263 <package>Debconf</package> or another tool that
1264 implements the Debian Configuration Management
1265 Specification will also be installed, and any
1266 versioned dependencies on it will be satisfied
1267 before preconfiguration begins.
1272 Packages which use the Debian Configuration Management
1273 Specification must allow for translation of their user-visible
1274 messages by using a gettext-based system such as the one
1275 provided by the <package>po-debconf</package> package.
1279 Packages should try to minimize the amount of prompting
1280 they need to do, and they should ensure that the user
1281 will only ever be asked each question once. This means
1282 that packages should try to use appropriate shared
1283 configuration files (such as <file>/etc/papersize</file> and
1284 <file>/etc/news/server</file>), and shared
1285 <package>debconf</package> variables rather than each
1286 prompting for their own list of required pieces of
1291 It also means that an upgrade should not ask the same
1292 questions again, unless the user has used
1293 <tt>dpkg --purge</tt> to remove the package's configuration.
1294 The answers to configuration questions should be stored in an
1295 appropriate place in <file>/etc</file> so that the user can
1296 modify them, and how this has been done should be
1301 If a package has a vitally important piece of
1302 information to pass to the user (such as "don't run me
1303 as I am, you must edit the following configuration files
1304 first or you risk your system emitting badly-formatted
1305 messages"), it should display this in the
1306 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1307 prompt the user to hit return to acknowledge the
1308 message. Copyright messages do not count as vitally
1309 important (they belong in
1310 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1311 neither do instructions on how to use a program (these
1312 should be in on-line documentation, where all the users
1317 Any necessary prompting should almost always be confined
1318 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1319 script. If it is done in the <prgn>postinst</prgn>, it
1320 should be protected with a conditional so that
1321 unnecessary prompting doesn't happen if a package's
1322 installation fails and the <prgn>postinst</prgn> is
1323 called with <tt>abort-upgrade</tt>,
1324 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1334 <heading>Source packages</heading>
1336 <sect id="standardsversion">
1337 <heading>Standards conformance</heading>
1340 Source packages should specify the most recent version number
1341 of this policy document with which your package complied
1342 when it was last updated.
1346 This information may be used to file bug reports
1347 automatically if your package becomes too much out of date.
1351 The version is specified in the <tt>Standards-Version</tt>
1353 The format of the <tt>Standards-Version</tt> field is
1354 described in <ref id="f-Standards-Version">.
1358 You should regularly, and especially if your package has
1359 become out of date, check for the newest Policy Manual
1360 available and update your package, if necessary. When your
1361 package complies with the new standards you should update the
1362 <tt>Standards-Version</tt> source package field and
1363 release it.<footnote>
1364 See the file <file>upgrading-checklist</file> for
1365 information about policy which has changed between
1366 different versions of this document.
1372 <sect id="pkg-relations">
1373 <heading>Package relationships</heading>
1376 Source packages should specify which binary packages they
1377 require to be installed or not to be installed in order to
1378 build correctly. For example, if building a package
1379 requires a certain compiler, then the compiler should be
1380 specified as a build-time dependency.
1384 It is not necessary to explicitly specify build-time
1385 relationships on a minimal set of packages that are always
1386 needed to compile, link and put in a Debian package a
1387 standard "Hello World!" program written in C or C++. The
1388 required packages are called <em>build-essential</em>, and
1389 an informational list can be found in
1390 <file>/usr/share/doc/build-essential/list</file> (which is
1391 contained in the <tt>build-essential</tt>
1394 <list compact="compact">
1396 This allows maintaining the list separately
1397 from the policy documents (the list does not
1398 need the kind of control that the policy
1402 Having a separate package allows one to install
1403 the build-essential packages on a machine, as
1404 well as allowing other packages such as tasks to
1405 require installation of the build-essential
1406 packages using the depends relation.
1409 The separate package allows bug reports against
1410 the list to be categorized separately from
1411 the policy management process in the BTS.
1418 When specifying the set of build-time dependencies, one
1419 should list only those packages explicitly required by the
1420 build. It is not necessary to list packages which are
1421 required merely because some other package in the list of
1422 build-time dependencies depends on them.<footnote>
1423 The reason for this is that dependencies change, and
1424 you should list all those packages, and <em>only</em>
1425 those packages that <em>you</em> need directly. What
1426 others need is their business. For example, if you
1427 only link against <file>libimlib</file>, you will need to
1428 build-depend on <package>libimlib2-dev</package> but
1429 not against any <tt>libjpeg*</tt> packages, even
1430 though <tt>libimlib2-dev</tt> currently depends on
1431 them: installation of <package>libimlib2-dev</package>
1432 will automatically ensure that all of its run-time
1433 dependencies are satisfied.
1438 If build-time dependencies are specified, it must be
1439 possible to build the package and produce working binaries
1440 on a system with only essential and build-essential
1441 packages installed and also those required to satisfy the
1442 build-time relationships (including any implied
1443 relationships). In particular, this means that version
1444 clauses should be used rigorously in build-time
1445 relationships so that one cannot produce bad or
1446 inconsistently configured packages when the relationships
1447 are properly satisfied.
1451 <ref id="relationships"> explains the technical details.
1456 <heading>Changes to the upstream sources</heading>
1459 If changes to the source code are made that are not
1460 specific to the needs of the Debian system, they should be
1461 sent to the upstream authors in whatever form they prefer
1462 so as to be included in the upstream version of the
1467 If you need to configure the package differently for
1468 Debian or for Linux, and the upstream source doesn't
1469 provide a way to do so, you should add such configuration
1470 facilities (for example, a new <prgn>autoconf</prgn> test
1471 or <tt>#define</tt>) and send the patch to the upstream
1472 authors, with the default set to the way they originally
1473 had it. You can then easily override the default in your
1474 <file>debian/rules</file> or wherever is appropriate.
1478 You should make sure that the <prgn>configure</prgn> utility
1479 detects the correct architecture specification string
1480 (refer to <ref id="arch-spec"> for details).
1484 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1485 <prgn>configure</prgn> scripts are used, you should edit the
1486 <file>.in</file> files rather than editing the
1487 <prgn>Makefile</prgn> directly. This allows the user to
1488 reconfigure the package if necessary. You should
1489 <em>not</em> configure the package and edit the generated
1490 <prgn>Makefile</prgn>! This makes it impossible for someone
1491 else to later reconfigure the package without losing the
1497 <sect id="dpkgchangelog">
1498 <heading>Debian changelog: <file>debian/changelog</file></heading>
1501 Changes in the Debian version of the package should be
1502 briefly explained in the Debian changelog file
1503 <file>debian/changelog</file>.<footnote>
1505 Mistakes in changelogs are usually best rectified by
1506 making a new changelog entry rather than "rewriting
1507 history" by editing old changelog entries.
1510 This includes modifications
1511 made in the Debian package compared to the upstream one
1512 as well as other changes and updates to the package.
1514 Although there is nothing stopping an author who is also
1515 the Debian maintainer from using this changelog for all
1516 their changes, it will have to be renamed if the Debian
1517 and upstream maintainers become different people. In such
1518 a case, however, it might be better to maintain the package
1519 as a non-native package.
1524 The format of the <file>debian/changelog</file> allows the
1525 package building tools to discover which version of the package
1526 is being built and find out other release-specific information.
1530 That format is a series of entries like this:
1532 <example compact="compact">
1533 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1535 [optional blank line(s), stripped]
1537 * <var>change details</var>
1538 <var>more change details</var>
1540 [blank line(s), included in output of dpkg-parsechangelog]
1542 * <var>even more change details</var>
1544 [optional blank line(s), stripped]
1546 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1551 <var>package</var> and <var>version</var> are the source
1552 package name and version number.
1556 <var>distribution(s)</var> lists the distributions where
1557 this version should be installed when it is uploaded - it
1558 is copied to the <tt>Distribution</tt> field in the
1559 <file>.changes</file> file. See <ref id="f-Distribution">.
1563 <var>urgency</var> is the value for the <tt>Urgency</tt>
1564 field in the <file>.changes</file> file for the upload
1565 (see <ref id="f-Urgency">). It is not possible to specify
1566 an urgency containing commas; commas are used to separate
1567 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1568 <prgn>dpkg</prgn> changelog format (though there is
1569 currently only one useful <var>keyword</var>,
1574 The change details may in fact be any series of lines
1575 starting with at least two spaces, but conventionally each
1576 change starts with an asterisk and a separating space and
1577 continuation lines are indented so as to bring them in
1578 line with the start of the text above. Blank lines may be
1579 used here to separate groups of changes, if desired.
1583 If this upload resolves bugs recorded in the Bug Tracking
1584 System (BTS), they may be automatically closed on the
1585 inclusion of this package into the Debian archive by
1586 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1587 in the change details.<footnote>
1588 To be precise, the string should match the following
1589 Perl regular expression:
1591 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1593 Then all of the bug numbers listed will be closed by the
1594 archive maintenance script (<prgn>katie</prgn>) using the
1595 <var>version</var> of the changelog entry.
1597 This information is conveyed via the <tt>Closes</tt> field
1598 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1602 The maintainer name and email address used in the changelog
1603 should be the details of the person uploading <em>this</em>
1604 version. They are <em>not</em> necessarily those of the
1605 usual package maintainer. The information here will be
1606 copied to the <tt>Changed-By</tt> field in the
1607 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1608 and then later used to send an acknowledgement when the
1609 upload has been installed.
1613 The <var>date</var> must be in RFC822 format<footnote>
1614 This is generated by <tt>date -R</tt>.
1615 </footnote>; it must include the time zone specified
1616 numerically, with the time zone name or abbreviation
1617 optionally present as a comment in parentheses.
1621 The first "title" line with the package name must start
1622 at the left hand margin. The "trailer" line with the
1623 maintainer and date details must be preceded by exactly
1624 one space. The maintainer details and the date must be
1625 separated by exactly two spaces.
1629 The entire changelog must be encoded in UTF-8.
1633 For more information on placement of the changelog files
1634 within binary packages, please see <ref id="changelogs">.
1638 <sect id="dpkgcopyright">
1639 <heading>Copyright: <file>debian/copyright</file></heading>
1641 Every package must be accompanied by a verbatim copy of
1642 its copyright and distribution license in the file
1643 <file>/usr/share/doc/<var>package</var>/copyright</file>
1644 (see <ref id="copyrightfile"> for further details). Also see
1645 <ref id="pkgcopyright"> for further considerations related
1646 to copyrights for packages.
1650 <heading>Error trapping in makefiles</heading>
1653 When <prgn>make</prgn> invokes a command in a makefile
1654 (including your package's upstream makefiles and
1655 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1656 means that <prgn>sh</prgn>'s usual bad error handling
1657 properties apply: if you include a miniature script as one
1658 of the commands in your makefile you'll find that if you
1659 don't do anything about it then errors are not detected
1660 and <prgn>make</prgn> will blithely continue after
1665 Every time you put more than one shell command (this
1666 includes using a loop) in a makefile command you
1667 must make sure that errors are trapped. For
1668 simple compound commands, such as changing directory and
1669 then running a program, using <tt>&&</tt> rather
1670 than semicolon as a command separator is sufficient. For
1671 more complex commands including most loops and
1672 conditionals you should include a separate <tt>set -e</tt>
1673 command at the start of every makefile command that's
1674 actually one of these miniature shell scripts.
1678 <sect id="timestamps">
1679 <heading>Time Stamps</heading>
1681 Maintainers should preserve the modification times of the
1682 upstream source files in a package, as far as is reasonably
1684 The rationale is that there is some information conveyed
1685 by knowing the age of the file, for example, you could
1686 recognize that some documentation is very old by looking
1687 at the modification time, so it would be nice if the
1688 modification time of the upstream source would be
1694 <sect id="restrictions">
1695 <heading>Restrictions on objects in source packages</heading>
1698 The source package may not contain any hard links<footnote>
1700 This is not currently detected when building source
1701 packages, but only when extracting
1705 Hard links may be permitted at some point in the
1706 future, but would require a fair amount of
1709 </footnote>, device special files, sockets or setuid or
1710 setgid files.<footnote>
1711 Setgid directories are allowed.
1716 <sect id="debianrules">
1717 <heading>Main building script: <file>debian/rules</file></heading>
1720 This file must be an executable makefile, and contains the
1721 package-specific recipes for compiling the package and
1722 building binary package(s) from the source.
1726 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1727 so that it can be invoked by saying its name rather than
1728 invoking <prgn>make</prgn> explicitly. That is, invoking
1729 either of <tt>make -f debian/rules <em>args...</em></tt>
1730 or <tt>./debian/rules <em>args...</em></tt> must result in
1735 Since an interactive <file>debian/rules</file> script makes it
1736 impossible to auto-compile that package and also makes it
1737 hard for other people to reproduce the same binary
1738 package, all <em>required targets</em> must be
1739 non-interactive. At a minimum, required targets are the
1740 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1741 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1742 <em>binary-indep</em>, and <em>build</em>. It also follows
1743 that any target that these targets depend on must also be
1748 The targets are as follows (required unless stated otherwise):
1750 <tag><tt>build</tt></tag>
1753 The <tt>build</tt> target should perform all the
1754 configuration and compilation of the package.
1755 If a package has an interactive pre-build
1756 configuration routine, the Debianized source package
1757 must either be built after this has taken place (so
1758 that the binary package can be built without rerunning
1759 the configuration) or the configuration routine
1760 modified to become non-interactive. (The latter is
1761 preferable if there are architecture-specific features
1762 detected by the configuration routine.)
1766 For some packages, notably ones where the same
1767 source tree is compiled in different ways to produce
1768 two binary packages, the <tt>build</tt> target
1769 does not make much sense. For these packages it is
1770 good enough to provide two (or more) targets
1771 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1772 for each of the ways of building the package, and a
1773 <tt>build</tt> target that does nothing. The
1774 <tt>binary</tt> target will have to build the
1775 package in each of the possible ways and make the
1776 binary package out of each.
1780 The <tt>build</tt> target must not do anything
1781 that might require root privilege.
1785 The <tt>build</tt> target may need to run the
1786 <tt>clean</tt> target first - see below.
1790 When a package has a configuration and build routine
1791 which takes a long time, or when the makefiles are
1792 poorly designed, or when <tt>build</tt> needs to
1793 run <tt>clean</tt> first, it is a good idea to
1794 <tt>touch build</tt> when the build process is
1795 complete. This will ensure that if <tt>debian/rules
1796 build</tt> is run again it will not rebuild the whole
1798 Another common way to do this is for <tt>build</tt>
1799 to depend on <prgn>build-stamp</prgn> and to do
1800 nothing else, and for the <prgn>build-stamp</prgn>
1801 target to do the building and to <tt>touch
1802 build-stamp</tt> on completion. This is
1803 especially useful if the build routine creates a
1804 file or directory called <tt>build</tt>; in such a
1805 case, <tt>build</tt> will need to be listed as
1806 a phony target (i.e., as a dependency of the
1807 <tt>.PHONY</tt> target). See the documentation of
1808 <prgn>make</prgn> for more information on phony
1814 <tag><tt>build-arch</tt> (optional),
1815 <tt>build-indep</tt> (optional)
1819 A package may also provide both of the targets
1820 <tt>build-arch</tt> and <tt>build-indep</tt>.
1821 The <tt>build-arch</tt> target, if provided, should
1822 perform all the configuration and compilation required
1823 for producing all architecture-dependant binary packages
1824 (those packages for which the body of the
1825 <tt>Architecture</tt> field in <tt>debian/control</tt>
1826 is not <tt>all</tt>).
1827 Similarly, the <tt>build-indep</tt> target, if
1828 provided, should perform all the configuration and
1829 compilation required for producing all
1830 architecture-independent binary packages
1831 (those packages for which the body of the
1832 <tt>Architecture</tt> field in <tt>debian/control</tt>
1834 The <tt>build</tt> target should depend on those of the
1835 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1836 are provided in the rules file.
1840 If one or both of the targets <tt>build-arch</tt> and
1841 <tt>build-indep</tt> are not provided, then invoking
1842 <file>debian/rules</file> with one of the not-provided
1843 targets as arguments should produce a exit status code
1844 of 2. Usually this is provided automatically by make
1845 if the target is missing.
1849 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1850 must not do anything that might require root privilege.
1854 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1855 <tt>binary-indep</tt>
1859 The <tt>binary</tt> target must be all that is
1860 necessary for the user to build the binary package(s)
1861 produced from this source package. It is
1862 split into two parts: <prgn>binary-arch</prgn> builds
1863 the binary packages which are specific to a particular
1864 architecture, and <tt>binary-indep</tt> builds
1865 those which are not.
1868 <tt>binary</tt> may be (and commonly is) a target with
1869 no commands which simply depends on
1870 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1873 Both <tt>binary-*</tt> targets should depend on the
1874 <tt>build</tt> target, or on the appropriate
1875 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1876 provided, so that the package is built if it has not
1877 been already. It should then create the relevant
1878 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1879 make their control files and <prgn>dpkg-deb</prgn> to
1880 build them and place them in the parent of the top
1885 Both the <tt>binary-arch</tt> and
1886 <tt>binary-indep</tt> targets <em>must</em> exist.
1887 If one of them has nothing to do (which will always be
1888 the case if the source generates only a single binary
1889 package, whether architecture-dependent or not), it
1890 must still exist and must always succeed.
1894 The <tt>binary</tt> targets must be invoked as
1896 The <prgn>fakeroot</prgn> package often allows one
1897 to build a package correctly even without being
1903 <tag><tt>clean</tt></tag>
1906 This must undo any effects that the <tt>build</tt>
1907 and <tt>binary</tt> targets may have had, except
1908 that it should leave alone any output files created in
1909 the parent directory by a run of a <tt>binary</tt>
1914 If a <tt>build</tt> file is touched at the end of
1915 the <tt>build</tt> target, as suggested above, it
1916 should be removed as the first action that
1917 <tt>clean</tt> performs, so that running
1918 <tt>build</tt> again after an interrupted
1919 <tt>clean</tt> doesn't think that everything is
1924 The <tt>clean</tt> target may need to be
1925 invoked as root if <tt>binary</tt> has been
1926 invoked since the last <tt>clean</tt>, or if
1927 <tt>build</tt> has been invoked as root (since
1928 <tt>build</tt> may create directories, for
1933 <tag><tt>get-orig-source</tt> (optional)</tag>
1936 This target fetches the most recent version of the
1937 original source package from a canonical archive site
1938 (via FTP or WWW, for example), does any necessary
1939 rearrangement to turn it into the original source
1940 tar file format described below, and leaves it in the
1945 This target may be invoked in any directory, and
1946 should take care to clean up any temporary files it
1951 This target is optional, but providing it if
1952 possible is a good idea.
1956 <tag><tt>patch</tt> (optional)</tag>
1959 This target performs whatever additional actions are
1960 required to make the source ready for editing (unpacking
1961 additional upstream archives, applying patches, etc.).
1962 It is recommended to be implemented for any package where
1963 <tt>dpkg-source -x</tt> does not result in source ready
1964 for additional modification. See
1965 <ref id="readmesource">.
1971 The <tt>build</tt>, <tt>binary</tt> and
1972 <tt>clean</tt> targets must be invoked with the current
1973 directory being the package's top-level directory.
1978 Additional targets may exist in <file>debian/rules</file>,
1979 either as published or undocumented interfaces or for the
1980 package's internal use.
1984 The architectures we build on and build for are determined
1985 by <prgn>make</prgn> variables using the utility
1986 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1987 You can determine the
1988 Debian architecture and the GNU style architecture
1989 specification string for the build machine (the machine type
1990 we are building on) as well as for the host machine (the
1991 machine type we are building for). Here is a list of
1992 supported <prgn>make</prgn> variables:
1993 <list compact="compact">
1995 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1998 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2001 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2004 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2005 specification string)
2008 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2009 <tt>DEB_*_GNU_TYPE</tt>)
2012 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2013 <tt>DEB_*_GNU_TYPE</tt>)
2015 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2016 the build machine or <tt>HOST</tt> for specification of the
2021 Backward compatibility can be provided in the rules file
2022 by setting the needed variables to suitable default
2023 values; please refer to the documentation of
2024 <prgn>dpkg-architecture</prgn> for details.
2028 It is important to understand that the <tt>DEB_*_ARCH</tt>
2029 string only determines which Debian architecture we are
2030 building on or for. It should not be used to get the CPU
2031 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2032 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2033 GNU style variables should generally only be used with upstream
2037 <sect1 id="debianrules-options">
2038 <heading><file>debian/rules</file> and
2039 <tt>DEB_BUILD_OPTIONS</tt></heading>
2042 Supporting the standardized environment variable
2043 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2044 contain several flags to change how a package is compiled and
2045 built. Each flag must be in the form <var>flag</var> or
2046 <var>flag</var>=<var>options</var>. If multiple flags are
2047 given, they must be separated by whitespace.<footnote>
2048 Some packages support any delimiter, but whitespace is the
2049 easiest to parse inside a makefile and avoids ambiguity with
2050 flag values that contain commas.
2052 <var>flag</var> must start with a lowercase letter
2053 (<tt>a-z</tt>) and consist only of lowercase letters,
2054 numbers (<tt>0-9</tt>), and the characters
2055 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2056 <var>options</var> must not contain whitespace. The same
2057 tag should not be given multiple times with conflicting
2058 values. Package maintainers may assume that
2059 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2063 The meaning of the following tags has been standardized:
2067 This tag says to not run any build-time test suite
2068 provided by the package.
2072 The presence of this tag means that the package should
2073 be compiled with a minimum of optimization. For C
2074 programs, it is best to add <tt>-O0</tt> to
2075 <tt>CFLAGS</tt> (although this is usually the default).
2076 Some programs might fail to build or run at this level
2077 of optimization; it may be necessary to use
2078 <tt>-O1</tt>, for example.
2082 This tag means that the debugging symbols should not be
2083 stripped from the binary during installation, so that
2084 debugging information may be included in the package.
2086 <tag>parallel=n</tag>
2088 This tag means that the package should be built using up
2089 to <tt>n</tt> parallel processes if the package build
2090 system supports this.<footnote>
2091 Packages built with <tt>make</tt> can often implement
2092 this by passing the <tt>-j</tt><var>n</var> option to
2095 If the package build system does not support parallel
2096 builds, this string must be ignored. If the package
2097 build system only supports a lower level of concurrency
2098 than <var>n</var>, the package should be built using as
2099 many parallel processes as the package build system
2100 supports. It is up to the package maintainer to decide
2101 whether the package build times are long enough and the
2102 package build system is robust enough to make supporting
2103 parallel builds worthwhile.
2109 Unknown flags must be ignored by <file>debian/rules</file>.
2113 The following makefile snippet is an example of how one may
2114 implement the build options; you will probably have to
2115 massage this example in order to make it work for your
2117 <example compact="compact">
2120 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2121 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2122 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2123 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2125 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2130 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2131 INSTALL_PROGRAM += -s
2133 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2134 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2135 MAKEFLAGS += -j$(NUMJOBS)
2140 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2141 # Code to run the package test suite.
2148 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2149 <sect id="substvars">
2150 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2153 When <prgn>dpkg-gencontrol</prgn>,
2154 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2155 generate control files they perform variable substitutions
2156 on their output just before writing it. Variable
2157 substitutions have the form <tt>${<var>variable</var>}</tt>.
2158 The optional file <file>debian/substvars</file> contains
2159 variable substitutions to be used; variables can also be set
2160 directly from <file>debian/rules</file> using the <tt>-V</tt>
2161 option to the source packaging commands, and certain
2162 predefined variables are also available.
2166 The <file>debian/substvars</file> file is usually generated and
2167 modified dynamically by <file>debian/rules</file> targets, in
2168 which case it must be removed by the <tt>clean</tt> target.
2172 See <manref name="deb-substvars" section="5"> for full
2173 details about source variable substitutions, including the
2174 format of <file>debian/substvars</file>.</p>
2177 <sect id="debianwatch">
2178 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2181 This is an optional, recommended control file for the
2182 <tt>uscan</tt> utility which defines how to automatically
2183 scan ftp or http sites for newly available updates of the
2184 package. This is used by <url id="
2185 http://dehs.alioth.debian.org/"> and other Debian QA tools
2186 to help with quality control and maintenance of the
2187 distribution as a whole.
2192 <sect id="debianfiles">
2193 <heading>Generated files list: <file>debian/files</file></heading>
2196 This file is not a permanent part of the source tree; it
2197 is used while building packages to record which files are
2198 being generated. <prgn>dpkg-genchanges</prgn> uses it
2199 when it generates a <file>.changes</file> file.
2203 It should not exist in a shipped source package, and so it
2204 (and any backup files or temporary files such as
2205 <file>files.new</file><footnote>
2206 <file>files.new</file> is used as a temporary file by
2207 <prgn>dpkg-gencontrol</prgn> and
2208 <prgn>dpkg-distaddfile</prgn> - they write a new
2209 version of <tt>files</tt> here before renaming it,
2210 to avoid leaving a corrupted copy if an error
2212 </footnote>) should be removed by the
2213 <tt>clean</tt> target. It may also be wise to
2214 ensure a fresh start by emptying or removing it at the
2215 start of the <tt>binary</tt> target.
2219 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2220 package, it adds an entry to <file>debian/files</file> for the
2221 <file>.deb</file> file that will be created when <tt>dpkg-deb
2222 --build</tt> is run for that binary package. So for most
2223 packages all that needs to be done with this file is to
2224 delete it in the <tt>clean</tt> target.
2228 If a package upload includes files besides the source
2229 package and any binary packages whose control files were
2230 made with <prgn>dpkg-gencontrol</prgn> then they should be
2231 placed in the parent of the package's top-level directory
2232 and <prgn>dpkg-distaddfile</prgn> should be called to add
2233 the file to the list in <file>debian/files</file>.</p>
2236 <sect id="embeddedfiles">
2237 <heading>Convenience copies of code</heading>
2240 Some software packages include in their distribution convenience
2241 copies of code from other software packages, generally so that
2242 users compiling from source don't have to download multiple
2243 packages. Debian packages should not make use of these
2244 convenience copies unless the included package is explicitly
2245 intended to be used in this way.<footnote>
2246 For example, parts of the GNU build system work like this.
2248 If the included code is already in the Debian archive in the
2249 form of a library, the Debian packaging should ensure that
2250 binary packages reference the libraries already in Debian and
2251 the convenience copy is not used. If the included code is not
2252 already in Debian, it should be packaged separately as a
2253 prerequisite if possible.
2255 Having multiple copies of the same code in Debian is
2256 inefficient, often creates either static linking or shared
2257 library conflicts, and, most importantly, increases the
2258 difficulty of handling security vulnerabilities in the
2264 <sect id="readmesource">
2265 <heading>Source package handling:
2266 <file>debian/README.source</file></heading>
2269 If running <prgn>dpkg-source -x</prgn> on a source package
2270 doesn't produce the source of the package, ready for editing,
2271 and allow one to make changes and run
2272 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2273 without taking any additional steps, creating a
2274 <file>debian/README.source</file> documentation file is
2275 recommended. This file should explain how to do all of the
2278 <item>Generate the fully patched source, in a form ready for
2279 editing, that would be built to create Debian
2280 packages. Doing this with a <tt>patch</tt> target in
2281 <file>debian/rules</file> is recommended; see
2282 <ref id="debianrules">.</item>
2283 <item>Modify the source and save those modifications so that
2284 they will be applied when building the package.</item>
2285 <item>Remove source modifications that are currently being
2286 applied when building the package.</item>
2287 <item>Optionally, document what steps are necessary to
2288 upgrade the Debian source package to a new upstream version,
2289 if applicable.</item>
2291 This explanation should include specific commands and mention
2292 any additional required Debian packages. It should not assume
2293 familiarity with any specific Debian packaging system or patch
2298 This explanation may refer to a documentation file installed by
2299 one of the package's build dependencies provided that the
2300 referenced documentation clearly explains these tasks and is not
2301 a general reference manual.
2305 <file>debian/README.source</file> may also include any other
2306 information that would be helpful to someone modifying the
2307 source package. Even if the package doesn't fit the above
2308 description, maintainers are encouraged to document in a
2309 <file>debian/README.source</file> file any source package with a
2310 particularly complex or unintuitive source layout or build
2311 system (for example, a package that builds the same source
2312 multiple times to generate different binary packages).
2318 <chapt id="controlfields">
2319 <heading>Control files and their fields</heading>
2322 The package management system manipulates data represented in
2323 a common format, known as <em>control data</em>, stored in
2324 <em>control files</em>.
2325 Control files are used for source packages, binary packages and
2326 the <file>.changes</file> files which control the installation
2327 of uploaded files<footnote>
2328 <prgn>dpkg</prgn>'s internal databases are in a similar
2333 <sect id="controlsyntax">
2334 <heading>Syntax of control files</heading>
2337 A control file consists of one or more paragraphs of
2339 The paragraphs are also sometimes referred to as stanzas.
2341 The paragraphs are separated by blank lines. Some control
2342 files allow only one paragraph; others allow several, in
2343 which case each paragraph usually refers to a different
2344 package. (For example, in source packages, the first
2345 paragraph refers to the source package, and later paragraphs
2346 refer to binary packages generated from the source.)
2350 Each paragraph consists of a series of data fields; each
2351 field consists of the field name, followed by a colon and
2352 then the data/value associated with that field. It ends at
2353 the end of the (logical) line. Horizontal whitespace
2354 (spaces and tabs) may occur immediately before or after the
2355 value and is ignored there; it is conventional to put a
2356 single space after the colon. For example, a field might
2358 <example compact="compact">
2361 the field name is <tt>Package</tt> and the field value
2366 Many fields' values may span several lines; in this case
2367 each continuation line must start with a space or a tab.
2368 Any trailing spaces or tabs at the end of individual
2369 lines of a field value are ignored.
2373 In fields where it is specified that lines may not wrap,
2374 only a single line of data is allowed and whitespace is not
2375 significant in a field body. Whitespace must not appear
2376 inside names (of packages, architectures, files or anything
2377 else) or version numbers, or between the characters of
2378 multi-character version relationships.
2382 Field names are not case-sensitive, but it is usual to
2383 capitalize the field names using mixed case as shown below.
2384 Field values are case-sensitive unless the description of the
2385 field says otherwise.
2389 Blank lines, or lines consisting only of spaces and tabs,
2390 are not allowed within field values or between fields - that
2391 would mean a new paragraph.
2395 All control files must be encoded in UTF-8.
2399 <sect id="sourcecontrolfiles">
2400 <heading>Source package control files -- <file>debian/control</file></heading>
2403 The <file>debian/control</file> file contains the most vital
2404 (and version-independent) information about the source package
2405 and about the binary packages it creates.
2409 The first paragraph of the control file contains information about
2410 the source package in general. The subsequent sets each describe a
2411 binary package that the source tree builds.
2415 The fields in the general paragraph (the first one, for the source
2418 <list compact="compact">
2419 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2420 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2421 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2422 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2423 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2424 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2425 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2426 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2431 The fields in the binary package paragraphs are:
2433 <list compact="compact">
2434 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2435 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2436 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2437 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2438 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2439 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2440 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2441 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2446 The syntax and semantics of the fields are described below.
2452 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2453 generate control files for binary packages (see below), by
2454 <prgn>dpkg-genchanges</prgn> to generate the
2455 <tt>.changes</tt> file to accompany the upload, and by
2456 <prgn>dpkg-source</prgn> when it creates the
2457 <file>.dsc</file> source control file as part of a source
2458 archive. Many fields are permitted to span multiple lines in
2459 <file>debian/control</file> but not in any other control
2460 file. These tools are responsible for removing the line
2461 breaks from such fields when using fields from
2462 <file>debian/control</file> to generate other control files.
2466 The fields here may contain variable references - their
2467 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2468 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2469 when they generate output control files.
2470 See <ref id="substvars"> for details.
2474 In addition to the control file syntax described <qref
2475 id="controlsyntax">above</qref>, this file may also contain
2476 comment lines starting with <tt>#</tt> without any preceding
2477 whitespace. All such lines are ignored, even in the middle of
2478 continuation lines for a multiline field, and do not end a
2484 <sect id="binarycontrolfiles">
2485 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2488 The <file>DEBIAN/control</file> file contains the most vital
2489 (and version-dependent) information about a binary package.
2493 The fields in this file are:
2495 <list compact="compact">
2496 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2497 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2498 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2499 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2500 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2501 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2502 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2503 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2504 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2505 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2506 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2507 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2512 <sect id="debiansourcecontrolfiles">
2513 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2516 This file contains a series of fields, identified and
2517 separated just like the fields in the control file of
2518 a binary package. The fields are listed below; their
2519 syntax is described above, in <ref id="pkg-controlfields">.
2521 <list compact="compact">
2522 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2523 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2524 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2525 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2526 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2527 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2528 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2529 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2530 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2531 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2532 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2537 The source package control file is generated by
2538 <prgn>dpkg-source</prgn> when it builds the source
2539 archive, from other files in the source package,
2540 described above. When unpacking, it is checked against
2541 the files and directories in the other parts of the
2547 <sect id="debianchangesfiles">
2548 <heading>Debian changes files -- <file>.changes</file></heading>
2551 The .changes files are used by the Debian archive maintenance
2552 software to process updates to packages. They contain one
2553 paragraph which contains information from the
2554 <tt>debian/control</tt> file and other data about the
2555 source package gathered via <tt>debian/changelog</tt>
2556 and <tt>debian/rules</tt>.
2560 The fields in this file are:
2562 <list compact="compact">
2563 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2564 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2569 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2570 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2571 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2572 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2573 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2574 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2575 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2576 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2581 <sect id="controlfieldslist">
2582 <heading>List of fields</heading>
2584 <sect1 id="f-Source">
2585 <heading><tt>Source</tt></heading>
2588 This field identifies the source package name.
2592 In <file>debian/control</file> or a <file>.dsc</file> file,
2593 this field must contain only the name of the source package.
2597 In a binary package control file or a <file>.changes</file>
2598 file, the source package name may be followed by a version
2599 number in parentheses<footnote>
2600 It is customary to leave a space after the package name
2601 if a version number is specified.
2603 This version number may be omitted (and is, by
2604 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2605 the <tt>Version</tt> field of the binary package in
2606 question. The field itself may be omitted from a binary
2607 package control file when the source package has the same
2608 name and version as the binary package.
2612 Package names (both source and binary,
2613 see <ref id="f-Package">) must consist only of lower case
2614 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2615 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2616 (<tt>.</tt>). They must be at least two characters long and
2617 must start with an alphanumeric character.
2621 <sect1 id="f-Maintainer">
2622 <heading><tt>Maintainer</tt></heading>
2625 The package maintainer's name and email address. The name
2626 should come first, then the email address inside angle
2627 brackets <tt><></tt> (in RFC822 format).
2631 If the maintainer's name contains a full stop then the
2632 whole field will not work directly as an email address due
2633 to a misfeature in the syntax specified in RFC822; a
2634 program using this field as an address must check for this
2635 and correct the problem if necessary (for example by
2636 putting the name in round brackets and moving it to the
2637 end, and bringing the email address forward).
2641 <sect1 id="f-Uploaders">
2642 <heading><tt>Uploaders</tt></heading>
2645 List of the names and email addresses of co-maintainers of
2646 the package, if any. If the package has other maintainers
2647 beside the one named in the
2648 <qref id="f-Maintainer">Maintainer field</qref>, their
2649 names and email addresses should be listed here. The
2650 format is the same as that of the Maintainer tag, and
2651 multiple entries should be comma separated. Currently,
2652 this field is restricted to a single line of data. This
2653 is an optional field.
2656 Any parser that interprets the Uploaders field in
2657 <file>debian/control</file> must permit it to span multiple
2658 lines. Line breaks in an Uploaders field that spans multiple
2659 lines are not significant and the semantics of the field are
2660 the same as if the line breaks had not been present.
2664 <sect1 id="f-Changed-By">
2665 <heading><tt>Changed-By</tt></heading>
2668 The name and email address of the person who changed the
2669 said package. Usually the name of the maintainer.
2670 All the rules for the Maintainer field apply here, too.
2674 <sect1 id="f-Section">
2675 <heading><tt>Section</tt></heading>
2678 This field specifies an application area into which the package
2679 has been classified. See <ref id="subsections">.
2683 When it appears in the <file>debian/control</file> file,
2684 it gives the value for the subfield of the same name in
2685 the <tt>Files</tt> field of the <file>.changes</file> file.
2686 It also gives the default for the same field in the binary
2691 <sect1 id="f-Priority">
2692 <heading><tt>Priority</tt></heading>
2695 This field represents how important it is that the user
2696 have the package installed. See <ref id="priorities">.
2700 When it appears in the <file>debian/control</file> file,
2701 it gives the value for the subfield of the same name in
2702 the <tt>Files</tt> field of the <file>.changes</file> file.
2703 It also gives the default for the same field in the binary
2708 <sect1 id="f-Package">
2709 <heading><tt>Package</tt></heading>
2712 The name of the binary package.
2716 Binary package names must follow the same syntax and
2717 restrictions as source package names. See <ref id="f-Source">
2722 <sect1 id="f-Architecture">
2723 <heading><tt>Architecture</tt></heading>
2726 Depending on context and the control file used, the
2727 <tt>Architecture</tt> field can include the following sets of
2730 <item>A unique single word identifying a Debian machine
2731 architecture as described in <ref id="arch-spec">.
2732 <item><tt>all</tt>, which indicates an
2733 architecture-independent package.
2734 <item><tt>any</tt>, which indicates a package available
2735 for building on any architecture.
2736 <item><tt>source</tt>, which indicates a source package.
2741 In the main <file>debian/control</file> file in the source
2742 package, this field may contain the special value
2743 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2744 architectures separated by spaces. If <tt>any</tt> or
2745 <tt>all</tt> appear, they must be the entire contents of the
2746 field. Most packages will use either <tt>any</tt> or
2747 <tt>all</tt>. Specifying a specific list of architectures is
2748 for the minority of cases where a program is not portable or
2749 is not useful on some architectures, and where possible the
2750 program should be made portable instead.
2754 In the source package control file <file>.dsc</file>, this
2755 field may contain either the special value <tt>any</tt> or a
2756 list of architectures separated by spaces. If a list is given,
2757 it may include (or consist solely of) the special value
2758 <tt>all</tt>. In other words, in <file>.dsc</file> files
2759 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2760 in combination with specific architectures. The
2761 <tt>Architecture</tt> field in the source package control file
2762 <file>.dsc</file> is generally constructed from the
2763 <tt>Architecture</tt> fields in the
2764 <file>debian/control</file> in the source package.
2768 Specifying <tt>any</tt> indicates that the source package
2769 isn't dependent on any particular architecture and should
2770 compile fine on any one. The produced binary package(s)
2771 will either be specific to whatever the current build
2772 architecture is or will be architecture-independent.
2776 Specifying only <tt>all</tt> indicates that the source package
2777 will only build architecture-independent packages. If this is
2778 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2779 <tt>any</tt> implies that the source package will build at
2780 least one architecture-dependent package.
2784 Specifying a list of architectures indicates that the source
2785 will build an architecture-dependent package, and will only
2786 work correctly on the listed architectures. If the source
2787 package also builds at least one architecture-independent
2788 package, <tt>all</tt> will also be included in the list.
2792 In a <file>.changes</file> file, the <tt>Architecture</tt>
2793 field lists the architecture(s) of the package(s)
2794 currently being uploaded. This will be a list; if the
2795 source for the package is also being uploaded, the special
2796 entry <tt>source</tt> is also present. <tt>all</tt> will be
2797 present if any architecture-independent packages are being
2798 uploaded. <tt>any</tt> may never occur in the
2799 <tt>Architecture</tt> field in the <file>.changes</file>
2804 See <ref id="debianrules"> for information on how to get
2805 the architecture for the build process.
2809 <sect1 id="f-Essential">
2810 <heading><tt>Essential</tt></heading>
2813 This is a boolean field which may occur only in the
2814 control file of a binary package or in a per-package fields
2815 paragraph of a main source control data file.
2819 If set to <tt>yes</tt> then the package management system
2820 will refuse to remove the package (upgrading and replacing
2821 it is still possible). The other possible value is <tt>no</tt>,
2822 which is the same as not having the field at all.
2827 <heading>Package interrelationship fields:
2828 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2829 <tt>Recommends</tt>, <tt>Suggests</tt>,
2830 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2831 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2835 These fields describe the package's relationships with
2836 other packages. Their syntax and semantics are described
2837 in <ref id="relationships">.</p>
2840 <sect1 id="f-Standards-Version">
2841 <heading><tt>Standards-Version</tt></heading>
2844 The most recent version of the standards (the policy
2845 manual and associated texts) with which the package
2850 The version number has four components: major and minor
2851 version number and major and minor patch level. When the
2852 standards change in a way that requires every package to
2853 change the major number will be changed. Significant
2854 changes that will require work in many packages will be
2855 signaled by a change to the minor number. The major patch
2856 level will be changed for any change to the meaning of the
2857 standards, however small; the minor patch level will be
2858 changed when only cosmetic, typographical or other edits
2859 are made which neither change the meaning of the document
2860 nor affect the contents of packages.
2864 Thus only the first three components of the policy version
2865 are significant in the <em>Standards-Version</em> control
2866 field, and so either these three components or all four
2867 components may be specified.<footnote>
2868 In the past, people specified the full version number
2869 in the Standards-Version field, for example "2.3.0.0".
2870 Since minor patch-level changes don't introduce new
2871 policy, it was thought it would be better to relax
2872 policy and only require the first 3 components to be
2873 specified, in this example "2.3.0". All four
2874 components may still be used if someone wishes to do so.
2880 <sect1 id="f-Version">
2881 <heading><tt>Version</tt></heading>
2884 The version number of a package. The format is:
2885 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2889 The three components here are:
2891 <tag><var>epoch</var></tag>
2894 This is a single (generally small) unsigned integer. It
2895 may be omitted, in which case zero is assumed. If it is
2896 omitted then the <var>upstream_version</var> may not
2901 It is provided to allow mistakes in the version numbers
2902 of older versions of a package, and also a package's
2903 previous version numbering schemes, to be left behind.
2907 <tag><var>upstream_version</var></tag>
2910 This is the main part of the version number. It is
2911 usually the version number of the original ("upstream")
2912 package from which the <file>.deb</file> file has been made,
2913 if this is applicable. Usually this will be in the same
2914 format as that specified by the upstream author(s);
2915 however, it may need to be reformatted to fit into the
2916 package management system's format and comparison
2921 The comparison behavior of the package management system
2922 with respect to the <var>upstream_version</var> is
2923 described below. The <var>upstream_version</var>
2924 portion of the version number is mandatory.
2928 The <var>upstream_version</var> may contain only
2929 alphanumerics<footnote>
2930 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2932 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2933 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2934 tilde) and should start with a digit. If there is no
2935 <var>debian_revision</var> then hyphens are not allowed;
2936 if there is no <var>epoch</var> then colons are not
2941 <tag><var>debian_revision</var></tag>
2944 This part of the version number specifies the version of
2945 the Debian package based on the upstream version. It
2946 may contain only alphanumerics and the characters
2947 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2948 tilde) and is compared in the same way as the
2949 <var>upstream_version</var> is.
2953 It is optional; if it isn't present then the
2954 <var>upstream_version</var> may not contain a hyphen.
2955 This format represents the case where a piece of
2956 software was written specifically to be turned into a
2957 Debian package, and so there is only one "debianisation"
2958 of it and therefore no revision indication is required.
2962 It is conventional to restart the
2963 <var>debian_revision</var> at <tt>1</tt> each time the
2964 <var>upstream_version</var> is increased.
2968 The package management system will break the version
2969 number apart at the last hyphen in the string (if there
2970 is one) to determine the <var>upstream_version</var> and
2971 <var>debian_revision</var>. The absence of a
2972 <var>debian_revision</var> is equivalent to a
2973 <var>debian_revision</var> of <tt>0</tt>.
2980 When comparing two version numbers, first the <var>epoch</var>
2981 of each are compared, then the <var>upstream_version</var> if
2982 <var>epoch</var> is equal, and then <var>debian_revision</var>
2983 if <var>upstream_version</var> is also equal.
2984 <var>epoch</var> is compared numerically. The
2985 <var>upstream_version</var> and <var>debian_revision</var>
2986 parts are compared by the package management system using the
2987 following algorithm:
2991 The strings are compared from left to right.
2995 First the initial part of each string consisting entirely of
2996 non-digit characters is determined. These two parts (one of
2997 which may be empty) are compared lexically. If a difference
2998 is found it is returned. The lexical comparison is a
2999 comparison of ASCII values modified so that all the letters
3000 sort earlier than all the non-letters and so that a tilde
3001 sorts before anything, even the end of a part. For example,
3002 the following parts are in sorted order from earliest to
3003 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3004 <tt>a</tt>.<footnote>
3005 One common use of <tt>~</tt> is for upstream pre-releases.
3006 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3007 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3012 Then the initial part of the remainder of each string which
3013 consists entirely of digit characters is determined. The
3014 numerical values of these two parts are compared, and any
3015 difference found is returned as the result of the comparison.
3016 For these purposes an empty string (which can only occur at
3017 the end of one or both version strings being compared) counts
3022 These two steps (comparing and removing initial non-digit
3023 strings and initial digit strings) are repeated until a
3024 difference is found or both strings are exhausted.
3028 Note that the purpose of epochs is to allow us to leave behind
3029 mistakes in version numbering, and to cope with situations
3030 where the version numbering scheme changes. It is
3031 <em>not</em> intended to cope with version numbers containing
3032 strings of letters which the package management system cannot
3033 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3034 silly orderings (the author of this manual has heard of a
3035 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3036 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3037 <tt>2</tt> and so forth).
3041 <sect1 id="f-Description">
3042 <heading><tt>Description</tt></heading>
3045 In a source or binary control file, the <tt>Description</tt>
3046 field contains a description of the binary package, consisting
3047 of two parts, the synopsis or the short description, and the
3048 long description. The field's format is as follows:
3053 Description: <single line synopsis>
3054 <extended description over several lines>
3059 The lines in the extended description can have these formats:
3065 Those starting with a single space are part of a paragraph.
3066 Successive lines of this form will be word-wrapped when
3067 displayed. The leading space will usually be stripped off.
3071 Those starting with two or more spaces. These will be
3072 displayed verbatim. If the display cannot be panned
3073 horizontally, the displaying program will line wrap them "hard"
3074 (i.e., without taking account of word breaks). If it can they
3075 will be allowed to trail off to the right. None, one or two
3076 initial spaces may be deleted, but the number of spaces
3077 deleted from each line will be the same (so that you can have
3078 indenting work correctly, for example).
3082 Those containing a single space followed by a single full stop
3083 character. These are rendered as blank lines. This is the
3084 <em>only</em> way to get a blank line<footnote>
3085 Completely empty lines will not be rendered as blank lines.
3086 Instead, they will cause the parser to think you're starting
3087 a whole new record in the control file, and will therefore
3088 likely abort with an error.
3093 Those containing a space, a full stop and some more characters.
3094 These are for future expansion. Do not use them.
3100 Do not use tab characters. Their effect is not predictable.
3104 See <ref id="descriptions"> for further information on this.
3108 In a <file>.changes</file> file, the <tt>Description</tt>
3109 field contains a summary of the descriptions for the packages
3110 being uploaded. For this case, the first line of the field
3111 value (the part on the same line as <tt>Description:</tt>) is
3112 always empty. The content of the field is expressed as
3113 continuation lines, one line per package. Each line is
3114 indented by one space and contains the name of a binary
3115 package, a space, a hyphen (<tt>-</tt>), a space, and the
3116 short description line from that package.
3120 <sect1 id="f-Distribution">
3121 <heading><tt>Distribution</tt></heading>
3124 In a <file>.changes</file> file or parsed changelog output
3125 this contains the (space-separated) name(s) of the
3126 distribution(s) where this version of the package should
3127 be installed. Valid distributions are determined by the
3128 archive maintainers.<footnote>
3129 Example distribution names in the Debian archive used in
3130 <file>.changes</file> files are:
3131 <taglist compact="compact">
3132 <tag><em>unstable</em></tag>
3134 This distribution value refers to the
3135 <em>developmental</em> part of the Debian distribution
3136 tree. Most new packages, new upstream versions of
3137 packages and bug fixes go into the <em>unstable</em>
3141 <tag><em>experimental</em></tag>
3143 The packages with this distribution value are deemed
3144 by their maintainers to be high risk. Oftentimes they
3145 represent early beta or developmental packages from
3146 various sources that the maintainers want people to
3147 try, but are not ready to be a part of the other parts
3148 of the Debian distribution tree.
3153 Others are used for updating stable releases or for
3154 security uploads. More information is available in the
3155 Debian Developer's Reference, section "The Debian
3159 The Debian archive software only supports listing a single
3160 distribution. Migration of packages to other distributions is
3161 handled outside of the upload process.
3166 <heading><tt>Date</tt></heading>
3169 This field includes the date the package was built or last edited.
3173 The value of this field is usually extracted from the
3174 <file>debian/changelog</file> file - see
3175 <ref id="dpkgchangelog">).
3179 <sect1 id="f-Format">
3180 <heading><tt>Format</tt></heading>
3183 This field specifies a format revision for the file.
3184 The most current format described in the Policy Manual
3185 is version <strong>1.5</strong>. The syntax of the
3186 format value is the same as that of a package version
3187 number except that no epoch or Debian revision is allowed
3188 - see <ref id="f-Version">.
3192 <sect1 id="f-Urgency">
3193 <heading><tt>Urgency</tt></heading>
3196 This is a description of how important it is to upgrade to
3197 this version from previous ones. It consists of a single
3198 keyword taking one of the values <tt>low</tt>,
3199 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3200 <tt>critical</tt><footnote>
3201 Other urgency values are supported with configuration
3202 changes in the archive software but are not used in Debian.
3203 The urgency affects how quickly a package will be considered
3204 for inclusion into the <tt>testing</tt> distribution and
3205 gives an indication of the importance of any fixes included
3206 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3207 treated as synonymous.
3208 </footnote> (not case-sensitive) followed by an optional
3209 commentary (separated by a space) which is usually in
3210 parentheses. For example:
3213 Urgency: low (HIGH for users of diversions)
3219 The value of this field is usually extracted from the
3220 <file>debian/changelog</file> file - see
3221 <ref id="dpkgchangelog">.
3225 <sect1 id="f-Changes">
3226 <heading><tt>Changes</tt></heading>
3229 This field contains the human-readable changes data, describing
3230 the differences between the last version and the current one.
3234 The first line of the field value (the part on the same line
3235 as <tt>Changes:</tt>) is always empty. The content of the
3236 field is expressed as continuation lines, with each line
3237 indented by at least one space. Blank lines must be
3238 represented by a line consisting only of a space and a full
3243 The value of this field is usually extracted from the
3244 <file>debian/changelog</file> file - see
3245 <ref id="dpkgchangelog">).
3249 Each version's change information should be preceded by a
3250 "title" line giving at least the version, distribution(s)
3251 and urgency, in a human-readable way.
3255 If data from several versions is being returned the entry
3256 for the most recent version should be returned first, and
3257 entries should be separated by the representation of a
3258 blank line (the "title" line may also be followed by the
3259 representation of a blank line).
3263 <sect1 id="f-Binary">
3264 <heading><tt>Binary</tt></heading>
3267 This field is a list of binary packages. Its syntax and
3268 meaning varies depending on the control file in which it
3273 When it appears in the <file>.dsc</file> file, it lists binary
3274 packages which a source package can produce, separated by
3276 A space after each comma is conventional.
3277 </footnote>. It may span multiple lines. The source package
3278 does not necessarily produce all of these binary packages for
3279 every architecture. The source control file doesn't contain
3280 details of which architectures are appropriate for which of
3281 the binary packages.
3285 When it appears in a <file>.changes</file> file, it lists the
3286 names of the binary packages being uploaded, separated by
3287 whitespace (not commas). It may span multiple lines.
3291 <sect1 id="f-Installed-Size">
3292 <heading><tt>Installed-Size</tt></heading>
3295 This field appears in the control files of binary packages,
3296 and in the <file>Packages</file> files. It gives an estimate
3297 of the total amount of disk space required to install the
3298 named package. Actual installed size may vary based on block
3299 size, file system properties, or actions taken by package
3304 The disk space is given as the integer value of the estimated
3305 installed size in bytes, divided by 1024 and rounded up.
3309 <sect1 id="f-Files">
3310 <heading><tt>Files</tt></heading>
3313 This field contains a list of files with information about
3314 each one. The exact information and syntax varies with
3319 In all cases, Files is a multiline field. The first line of
3320 the field value (the part on the same line as <tt>Files:</tt>)
3321 is always empty. The content of the field is expressed as
3322 continuation lines, one line per file. Each line must be
3323 indented by one space and contain a number of sub-fields,
3324 separated by spaces, as described below.
3328 In the <file>.dsc</file> file, each line contains the MD5
3329 checksum, size and filename of the tar file and (if
3330 applicable) diff file which make up the remainder of the
3331 source package<footnote>
3332 That is, the parts which are not the <tt>.dsc</tt>.
3333 </footnote>. For example:
3336 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3337 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3339 The exact forms of the filenames are described
3340 in <ref id="pkg-sourcearchives">.
3344 In the <file>.changes</file> file this contains one line per
3345 file being uploaded. Each line contains the MD5 checksum,
3346 size, section and priority and the filename. For example:
3349 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3350 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3351 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3352 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3354 The <qref id="f-Section">section</qref>
3355 and <qref id="f-Priority">priority</qref> are the values of
3356 the corresponding fields in the main source control file. If
3357 no section or priority is specified then <tt>-</tt> should be
3358 used, though section and priority values must be specified for
3359 new packages to be installed properly.
3363 The special value <tt>byhand</tt> for the section in a
3364 <tt>.changes</tt> file indicates that the file in question
3365 is not an ordinary package file and must by installed by
3366 hand by the distribution maintainers. If the section is
3367 <tt>byhand</tt> the priority should be <tt>-</tt>.
3371 If a new Debian revision of a package is being shipped and
3372 no new original source archive is being distributed the
3373 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3374 entry for the original source archive
3375 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3376 but the <file>.changes</file> file should leave it out. In
3377 this case the original source archive on the distribution
3378 site must match exactly, byte-for-byte, the original
3379 source archive which was used to generate the
3380 <file>.dsc</file> file and diff which are being uploaded.</p>
3383 <sect1 id="f-Closes">
3384 <heading><tt>Closes</tt></heading>
3387 A space-separated list of bug report numbers that the upload
3388 governed by the .changes file closes.
3392 <sect1 id="f-Homepage">
3393 <heading><tt>Homepage</tt></heading>
3396 The URL of the web site for this package, preferably (when
3397 applicable) the site from which the original source can be
3398 obtained and any additional upstream documentation or
3399 information may be found. The content of this field is a
3400 simple URL without any surrounding characters such as
3408 <heading>User-defined fields</heading>
3411 Additional user-defined fields may be added to the
3412 source package control file. Such fields will be
3413 ignored, and not copied to (for example) binary or
3414 source package control files or upload control files.
3418 If you wish to add additional unsupported fields to
3419 these output files you should use the mechanism
3424 Fields in the main source control information file with
3425 names starting <tt>X</tt>, followed by one or more of
3426 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3427 be copied to the output files. Only the part of the
3428 field name after the hyphen will be used in the output
3429 file. Where the letter <tt>B</tt> is used the field
3430 will appear in binary package control files, where the
3431 letter <tt>S</tt> is used in source package control
3432 files and where <tt>C</tt> is used in upload control
3433 (<tt>.changes</tt>) files.
3437 For example, if the main source information control file
3440 XBS-Comment: I stand between the candle and the star.
3442 then the binary and source package control files will contain the
3445 Comment: I stand between the candle and the star.
3454 <chapt id="maintainerscripts">
3455 <heading>Package maintainer scripts and installation procedure</heading>
3458 <heading>Introduction to package maintainer scripts</heading>
3461 It is possible to supply scripts as part of a package which
3462 the package management system will run for you when your
3463 package is installed, upgraded or removed.
3467 These scripts are the files <prgn>preinst</prgn>,
3468 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3469 <prgn>postrm</prgn> in the control area of the package.
3470 They must be proper executable files; if they are scripts
3471 (which is recommended), they must start with the usual
3472 <tt>#!</tt> convention. They should be readable and
3473 executable by anyone, and must not be world-writable.
3477 The package management system looks at the exit status from
3478 these scripts. It is important that they exit with a
3479 non-zero status if there is an error, so that the package
3480 management system can stop its processing. For shell
3481 scripts this means that you <em>almost always</em> need to
3482 use <tt>set -e</tt> (this is usually true when writing shell
3483 scripts, in fact). It is also important, of course, that
3484 they exit with a zero status if everything went well.
3488 Additionally, packages interacting with users using
3489 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3490 install a <prgn>config</prgn> script in the control area,
3491 see <ref id="maintscriptprompt"> for details.
3495 When a package is upgraded a combination of the scripts from
3496 the old and new packages is called during the upgrade
3497 procedure. If your scripts are going to be at all
3498 complicated you need to be aware of this, and may need to
3499 check the arguments to your scripts.
3503 Broadly speaking the <prgn>preinst</prgn> is called before
3504 (a particular version of) a package is installed, and the
3505 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3506 before (a version of) a package is removed and the
3507 <prgn>postrm</prgn> afterwards.
3511 Programs called from maintainer scripts should not normally
3512 have a path prepended to them. Before installation is
3513 started, the package management system checks to see if the
3514 programs <prgn>ldconfig</prgn>,
3515 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3516 and <prgn>update-rc.d</prgn> can be found via the
3517 <tt>PATH</tt> environment variable. Those programs, and any
3518 other program that one would expect to be in the
3519 <tt>PATH</tt>, should thus be invoked without an absolute
3520 pathname. Maintainer scripts should also not reset the
3521 <tt>PATH</tt>, though they might choose to modify it by
3522 prepending or appending package-specific directories. These
3523 considerations really apply to all shell scripts.</p>
3526 <sect id="idempotency">
3527 <heading>Maintainer scripts idempotency</heading>
3530 It is necessary for the error recovery procedures that the
3531 scripts be idempotent. This means that if it is run
3532 successfully, and then it is called again, it doesn't bomb
3533 out or cause any harm, but just ensures that everything is
3534 the way it ought to be. If the first call failed, or
3535 aborted half way through for some reason, the second call
3536 should merely do the things that were left undone the first
3537 time, if any, and exit with a success status if everything
3539 This is so that if an error occurs, the user interrupts
3540 <prgn>dpkg</prgn> or some other unforeseen circumstance
3541 happens you don't leave the user with a badly-broken
3542 package when <prgn>dpkg</prgn> attempts to repeat the
3548 <sect id="controllingterminal">
3549 <heading>Controlling terminal for maintainer scripts</heading>
3552 The maintainer scripts are guaranteed to run with a
3553 controlling terminal and can interact with the user.
3554 Because these scripts may be executed with standard output
3555 redirected into a pipe for logging purposes, Perl scripts
3556 should set unbuffered output by setting <tt>$|=1</tt> so
3557 that the output is printed immediately rather than being
3561 <sect id="exitstatus">
3562 <heading>Exit status</heading>
3565 Each script must return a zero exit status for
3566 success, or a nonzero one for failure, since the package
3567 management system looks for the exit status of these scripts
3568 and determines what action to take next based on that datum.
3572 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3577 <list compact="compact">
3579 <var>new-preinst</var> <tt>install</tt>
3582 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3585 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3588 <var>old-preinst</var> <tt>abort-upgrade</tt>
3589 <var>new-version</var>
3594 <list compact="compact">
3596 <var>postinst</var> <tt>configure</tt>
3597 <var>most-recently-configured-version</var>
3600 <var>old-postinst</var> <tt>abort-upgrade</tt>
3601 <var>new-version</var>
3604 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3605 <tt>in-favour</tt> <var>package</var>
3606 <var>new-version</var>
3609 <var>postinst</var> <tt>abort-remove</tt>
3612 <var>deconfigured's-postinst</var>
3613 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3614 <var>failed-install-package</var> <var>version</var>
3615 [<tt>removing</tt> <var>conflicting-package</var>
3621 <list compact="compact">
3623 <var>prerm</var> <tt>remove</tt>
3626 <var>old-prerm</var> <tt>upgrade</tt>
3627 <var>new-version</var>
3630 <var>new-prerm</var> <tt>failed-upgrade</tt>
3631 <var>old-version</var>
3634 <var>conflictor's-prerm</var> <tt>remove</tt>
3635 <tt>in-favour</tt> <var>package</var>
3636 <var>new-version</var>
3639 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3640 <tt>in-favour</tt> <var>package-being-installed</var>
3641 <var>version</var> [<tt>removing</tt>
3642 <var>conflicting-package</var>
3648 <list compact="compact">
3650 <var>postrm</var> <tt>remove</tt>
3653 <var>postrm</var> <tt>purge</tt>
3656 <var>old-postrm</var> <tt>upgrade</tt>
3657 <var>new-version</var>
3660 <var>new-postrm</var> <tt>failed-upgrade</tt>
3661 <var>old-version</var>
3664 <var>new-postrm</var> <tt>abort-install</tt>
3667 <var>new-postrm</var> <tt>abort-install</tt>
3668 <var>old-version</var>
3671 <var>new-postrm</var> <tt>abort-upgrade</tt>
3672 <var>old-version</var>
3675 <var>disappearer's-postrm</var> <tt>disappear</tt>
3676 <var>overwriter</var>
3677 <var>overwriter-version</var>
3683 <sect id="unpackphase">
3684 <heading>Details of unpack phase of installation or upgrade</heading>
3687 The procedure on installation/upgrade/overwrite/disappear
3688 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3689 stage of <tt>dpkg --install</tt>) is as follows. In each
3690 case, if a major error occurs (unless listed below) the
3691 actions are, in general, run backwards - this means that the
3692 maintainer scripts are run with different arguments in
3693 reverse order. These are the "error unwind" calls listed
3700 If a version of the package is already installed, call
3701 <example compact="compact">
3702 <var>old-prerm</var> upgrade <var>new-version</var>
3706 If the script runs but exits with a non-zero
3707 exit status, <prgn>dpkg</prgn> will attempt:
3708 <example compact="compact">
3709 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3711 If this works, the upgrade continues. If this
3712 does not work, the error unwind:
3713 <example compact="compact">
3714 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3716 If this works, then the old-version is
3717 "Installed", if not, the old version is in a
3718 "Failed-Config" state.
3724 If a "conflicting" package is being removed at the same time,
3725 or if any package will be broken (due to <tt>Breaks</tt>):
3728 If <tt>--auto-deconfigure</tt> is
3729 specified, call, for each package to be deconfigured
3730 due to <tt>Breaks</tt>:
3731 <example compact="compact">
3732 <var>deconfigured's-prerm</var> deconfigure \
3733 in-favour <var>package-being-installed</var> <var>version</var>
3736 <example compact="compact">
3737 <var>deconfigured's-postinst</var> abort-deconfigure \
3738 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3740 The deconfigured packages are marked as
3741 requiring configuration, so that if
3742 <tt>--install</tt> is used they will be
3743 configured again if possible.
3746 If any packages depended on a conflicting
3747 package being removed and <tt>--auto-deconfigure</tt> is
3748 specified, call, for each such package:
3749 <example compact="compact">
3750 <var>deconfigured's-prerm</var> deconfigure \
3751 in-favour <var>package-being-installed</var> <var>version</var> \
3752 removing <var>conflicting-package</var> <var>version</var>
3755 <example compact="compact">
3756 <var>deconfigured's-postinst</var> abort-deconfigure \
3757 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3758 removing <var>conflicting-package</var> <var>version</var>
3760 The deconfigured packages are marked as
3761 requiring configuration, so that if
3762 <tt>--install</tt> is used they will be
3763 configured again if possible.
3766 To prepare for removal of each conflicting package, call:
3767 <example compact="compact">
3768 <var>conflictor's-prerm</var> remove \
3769 in-favour <var>package</var> <var>new-version</var>
3772 <example compact="compact">
3773 <var>conflictor's-postinst</var> abort-remove \
3774 in-favour <var>package</var> <var>new-version</var>
3783 If the package is being upgraded, call:
3784 <example compact="compact">
3785 <var>new-preinst</var> upgrade <var>old-version</var>
3787 If this fails, we call:
3789 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3796 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3798 is called. If this works, then the old version
3799 is in an "Installed" state, or else it is left
3800 in an "Unpacked" state.
3805 If it fails, then the old version is left
3806 in an "Half-Installed" state.
3813 Otherwise, if the package had some configuration
3814 files from a previous version installed (i.e., it
3815 is in the "configuration files only" state):
3816 <example compact="compact">
3817 <var>new-preinst</var> install <var>old-version</var>
3821 <var>new-postrm</var> abort-install <var>old-version</var>
3823 If this fails, the package is left in a
3824 "Half-Installed" state, which requires a
3825 reinstall. If it works, the packages is left in
3826 a "Config Files" state.
3829 Otherwise (i.e., the package was completely purged):
3830 <example compact="compact">
3831 <var>new-preinst</var> install
3834 <example compact="compact">
3835 <var>new-postrm</var> abort-install
3837 If the error-unwind fails, the package is in a
3838 "Half Installed" phase, and requires a
3839 reinstall. If the error unwind works, the
3840 package is in a not installed state.
3847 The new package's files are unpacked, overwriting any
3848 that may be on the system already, for example any
3849 from the old version of the same package or from
3850 another package. Backups of the old files are kept
3851 temporarily, and if anything goes wrong the package
3852 management system will attempt to put them back as
3853 part of the error unwind.
3857 It is an error for a package to contain files which
3858 are on the system in another package, unless
3859 <tt>Replaces</tt> is used (see <ref id="replaces">).
3861 The following paragraph is not currently the case:
3862 Currently the <tt>- - force-overwrite</tt> flag is
3863 enabled, downgrading it to a warning, but this may not
3869 It is a more serious error for a package to contain a
3870 plain file or other kind of non-directory where another
3871 package has a directory (again, unless
3872 <tt>Replaces</tt> is used). This error can be
3873 overridden if desired using
3874 <tt>--force-overwrite-dir</tt>, but this is not
3879 Packages which overwrite each other's files produce
3880 behavior which, though deterministic, is hard for the
3881 system administrator to understand. It can easily
3882 lead to "missing" programs if, for example, a package
3883 is installed which overwrites a file from another
3884 package, and is then removed again.<footnote>
3885 Part of the problem is due to what is arguably a
3886 bug in <prgn>dpkg</prgn>.
3891 A directory will never be replaced by a symbolic link
3892 to a directory or vice versa; instead, the existing
3893 state (symlink or not) will be left alone and
3894 <prgn>dpkg</prgn> will follow the symlink if there is
3903 If the package is being upgraded, call
3904 <example compact="compact">
3905 <var>old-postrm</var> upgrade <var>new-version</var>
3909 If this fails, <prgn>dpkg</prgn> will attempt:
3910 <example compact="compact">
3911 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3913 If this works, installation continues. If not,
3915 <example compact="compact">
3916 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3918 If this fails, the old version is left in a
3919 "Half Installed" state. If it works, dpkg now
3921 <example compact="compact">
3922 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3924 If this fails, the old version is left in a
3925 "Half Installed" state. If it works, dpkg now
3927 <example compact="compact">
3928 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3930 If this fails, the old version is in an
3937 This is the point of no return - if
3938 <prgn>dpkg</prgn> gets this far, it won't back off
3939 past this point if an error occurs. This will
3940 leave the package in a fairly bad state, which
3941 will require a successful re-installation to clear
3942 up, but it's when <prgn>dpkg</prgn> starts doing
3943 things that are irreversible.
3948 Any files which were in the old version of the package
3949 but not in the new are removed.
3953 The new file list replaces the old.
3957 The new maintainer scripts replace the old.
3961 Any packages all of whose files have been overwritten
3962 during the installation, and which aren't required for
3963 dependencies, are considered to have been removed.
3964 For each such package
3967 <prgn>dpkg</prgn> calls:
3968 <example compact="compact">
3969 <var>disappearer's-postrm</var> disappear \
3970 <var>overwriter</var> <var>overwriter-version</var>
3974 The package's maintainer scripts are removed.
3977 It is noted in the status database as being in a
3978 sane state, namely not installed (any conffiles
3979 it may have are ignored, rather than being
3980 removed by <prgn>dpkg</prgn>). Note that
3981 disappearing packages do not have their prerm
3982 called, because <prgn>dpkg</prgn> doesn't know
3983 in advance that the package is going to
3990 Any files in the package we're unpacking that are also
3991 listed in the file lists of other packages are removed
3992 from those lists. (This will lobotomize the file list
3993 of the "conflicting" package if there is one.)
3997 The backup files made during installation, above, are
4003 The new package's status is now sane, and recorded as
4008 Here is another point of no return - if the
4009 conflicting package's removal fails we do not unwind
4010 the rest of the installation; the conflicting package
4011 is left in a half-removed limbo.
4016 If there was a conflicting package we go and do the
4017 removal actions (described below), starting with the
4018 removal of the conflicting package's files (any that
4019 are also in the package being installed have already
4020 been removed from the conflicting package's file list,
4021 and so do not get removed now).
4027 <sect id="configdetails"><heading>Details of configuration</heading>
4030 When we configure a package (this happens with <tt>dpkg
4031 --install</tt> and <tt>dpkg --configure</tt>), we first
4032 update any <tt>conffile</tt>s and then call:
4033 <example compact="compact">
4034 <var>postinst</var> configure <var>most-recently-configured-version</var>
4039 No attempt is made to unwind after errors during
4040 configuration. If the configuration fails, the package is in
4041 a "Failed Config" state, and an error message is generated.
4045 If there is no most recently configured version
4046 <prgn>dpkg</prgn> will pass a null argument.
4049 Historical note: Truly ancient (pre-1997) versions of
4050 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4051 (including the angle brackets) in this case. Even older
4052 ones did not pass a second argument at all, under any
4053 circumstance. Note that upgrades using such an old dpkg
4054 version are unlikely to work for other reasons, even if
4055 this old argument behavior is handled by your postinst script.
4061 <sect id="removedetails"><heading>Details of removal and/or
4062 configuration purging</heading>
4068 <example compact="compact">
4069 <var>prerm</var> remove
4073 If prerm fails during replacement due to conflict
4075 <var>conflictor's-postinst</var> abort-remove \
4076 in-favour <var>package</var> <var>new-version</var>
4080 <var>postinst</var> abort-remove
4084 If this fails, the package is in a "Failed-Config"
4085 state, or else it remains "Installed".
4089 The package's files are removed (except <tt>conffile</tt>s).
4092 <example compact="compact">
4093 <var>postrm</var> remove
4097 If it fails, there's no error unwind, and the package is in
4098 an "Half-Installed" state.
4103 All the maintainer scripts except the <prgn>postrm</prgn>
4108 If we aren't purging the package we stop here. Note
4109 that packages which have no <prgn>postrm</prgn> and no
4110 <tt>conffile</tt>s are automatically purged when
4111 removed, as there is no difference except for the
4112 <prgn>dpkg</prgn> status.
4116 The <tt>conffile</tt>s and any backup files
4117 (<tt>~</tt>-files, <tt>#*#</tt> files,
4118 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4123 <example compact="compact">
4124 <var>postrm</var> purge
4128 If this fails, the package remains in a "Config-Files"
4133 The package's file list is removed.
4142 <chapt id="relationships">
4143 <heading>Declaring relationships between packages</heading>
4145 <sect id="depsyntax">
4146 <heading>Syntax of relationship fields</heading>
4149 These fields all have a uniform syntax. They are a list of
4150 package names separated by commas.
4154 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4155 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4156 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4157 control file fields of the package, which declare
4158 dependencies on other packages, the package names listed may
4159 also include lists of alternative package names, separated
4160 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4161 if any one of the alternative packages is installed, that
4162 part of the dependency is considered to be satisfied.
4166 All of the fields except for <tt>Provides</tt> may restrict
4167 their applicability to particular versions of each named
4168 package. This is done in parentheses after each individual
4169 package name; the parentheses should contain a relation from
4170 the list below followed by a version number, in the format
4171 described in <ref id="f-Version">.
4175 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4176 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4177 strictly earlier, earlier or equal, exactly equal, later or
4178 equal and strictly later, respectively. The deprecated
4179 forms <tt><</tt> and <tt>></tt> were used to mean
4180 earlier/later or equal, rather than strictly earlier/later,
4181 so they should not appear in new packages (though
4182 <prgn>dpkg</prgn> still supports them).
4186 Whitespace may appear at any point in the version
4187 specification subject to the rules in <ref
4188 id="controlsyntax">, and must appear where it's necessary to
4189 disambiguate; it is not otherwise significant. All of the
4190 relationship fields may span multiple lines. For
4191 consistency and in case of future changes to
4192 <prgn>dpkg</prgn> it is recommended that a single space be
4193 used after a version relationship and before a version
4194 number; it is also conventional to put a single space after
4195 each comma, on either side of each vertical bar, and before
4196 each open parenthesis. When wrapping a relationship field, it
4197 is conventional to do so after a comma and before the space
4198 following that comma.
4202 For example, a list of dependencies might appear as:
4203 <example compact="compact">
4206 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4211 All fields that specify build-time relationships
4212 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4213 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4214 may be restricted to a certain set of architectures. This
4215 is indicated in brackets after each individual package name and
4216 the optional version specification. The brackets enclose a
4217 list of Debian architecture names separated by whitespace.
4218 Exclamation marks may be prepended to each of the names.
4219 (It is not permitted for some names to be prepended with
4220 exclamation marks while others aren't.) If the current Debian
4221 host architecture is not in this list and there are no
4222 exclamation marks in the list, or it is in the list with a
4223 prepended exclamation mark, the package name and the
4224 associated version specification are ignored completely for
4225 the purposes of defining the relationships.
4230 <example compact="compact">
4232 Build-Depends-Indep: texinfo
4233 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4234 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4236 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4237 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4238 <tt>gnumach-dev</tt> only on hurd-i386.
4242 If the architecture-restricted dependency is part of a set of
4243 alternatives using <tt>|</tt>, that alternative is ignored
4244 completely on architectures that do not match the restriction.
4246 <example compact="compact">
4247 Build-Depends: foo [!i386] | bar [!amd64]
4249 is equivalent to <tt>bar</tt> on the i386 architecture, to
4250 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4251 bar</tt> on all other architectures.
4255 Note that the binary package relationship fields such as
4256 <tt>Depends</tt> appear in one of the binary package
4257 sections of the control file, whereas the build-time
4258 relationships such as <tt>Build-Depends</tt> appear in the
4259 source package section of the control file (which is the
4264 <sect id="binarydeps">
4265 <heading>Binary Dependencies - <tt>Depends</tt>,
4266 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4267 <tt>Pre-Depends</tt>
4271 Packages can declare in their control file that they have
4272 certain relationships to other packages - for example, that
4273 they may not be installed at the same time as certain other
4274 packages, and/or that they depend on the presence of others.
4278 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4279 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4280 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4281 <tt>Breaks</tt> is described in <ref id="breaks">, and
4282 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4283 rest are described below.
4287 These seven fields are used to declare a dependency
4288 relationship by one package on another. Except for
4289 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4290 depending (binary) package's control file.
4291 (<tt>Enhances</tt> appears in the recommending package's
4292 control file, and <tt>Breaks</tt> appears in the version of
4293 depended-on package which causes the named package to
4298 A <tt>Depends</tt> field takes effect <em>only</em> when a
4299 package is to be configured. It does not prevent a package
4300 being on the system in an unconfigured state while its
4301 dependencies are unsatisfied, and it is possible to replace
4302 a package whose dependencies are satisfied and which is
4303 properly installed with a different version whose
4304 dependencies are not and cannot be satisfied; when this is
4305 done the depending package will be left unconfigured (since
4306 attempts to configure it will give errors) and will not
4307 function properly. If it is necessary, a
4308 <tt>Pre-Depends</tt> field can be used, which has a partial
4309 effect even when a package is being unpacked, as explained
4310 in detail below. (The other three dependency fields,
4311 <tt>Recommends</tt>, <tt>Suggests</tt> and
4312 <tt>Enhances</tt>, are only used by the various front-ends
4313 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4314 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4318 For this reason packages in an installation run are usually
4319 all unpacked first and all configured later; this gives
4320 later versions of packages with dependencies on later
4321 versions of other packages the opportunity to have their
4322 dependencies satisfied.
4326 In case of circular dependencies, since installation or
4327 removal order honoring the dependency order can't be
4328 established, dependency loops are broken at some point
4329 (based on rules below), and some packages may not be able to
4330 rely on their dependencies being present when being
4331 installed or removed, depending on which side of the break
4332 of the circular dependency loop they happen to be on. If one
4333 of the packages in the loop has no postinst script, then the
4334 cycle will be broken at that package, so as to ensure that
4335 all postinst scripts run with the dependencies properly
4336 configured if this is possible. Otherwise the breaking point
4341 The <tt>Depends</tt> field thus allows package maintainers
4342 to impose an order in which packages should be configured.
4346 The meaning of the five dependency fields is as follows:
4348 <tag><tt>Depends</tt></tag>
4351 This declares an absolute dependency. A package will
4352 not be configured unless all of the packages listed in
4353 its <tt>Depends</tt> field have been correctly
4358 The <tt>Depends</tt> field should be used if the
4359 depended-on package is required for the depending
4360 package to provide a significant amount of
4365 The <tt>Depends</tt> field should also be used if the
4366 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4367 <prgn>postrm</prgn> scripts require the package to be
4368 present in order to run. Note, however, that the
4369 <prgn>postrm</prgn> cannot rely on any non-essential
4370 packages to be present during the <tt>purge</tt>
4374 <tag><tt>Recommends</tt></tag>
4377 This declares a strong, but not absolute, dependency.
4381 The <tt>Recommends</tt> field should list packages
4382 that would be found together with this one in all but
4383 unusual installations.
4387 <tag><tt>Suggests</tt></tag>
4389 This is used to declare that one package may be more
4390 useful with one or more others. Using this field
4391 tells the packaging system and the user that the
4392 listed packages are related to this one and can
4393 perhaps enhance its usefulness, but that installing
4394 this one without them is perfectly reasonable.
4397 <tag><tt>Enhances</tt></tag>
4399 This field is similar to Suggests but works in the
4400 opposite direction. It is used to declare that a
4401 package can enhance the functionality of another
4405 <tag><tt>Pre-Depends</tt></tag>
4408 This field is like <tt>Depends</tt>, except that it
4409 also forces <prgn>dpkg</prgn> to complete installation
4410 of the packages named before even starting the
4411 installation of the package which declares the
4412 pre-dependency, as follows:
4416 When a package declaring a pre-dependency is about to
4417 be <em>unpacked</em> the pre-dependency can be
4418 satisfied if the depended-on package is either fully
4419 configured, <em>or even if</em> the depended-on
4420 package(s) are only unpacked or half-configured,
4421 provided that they have been configured correctly at
4422 some point in the past (and not removed or partially
4423 removed since). In this case, both the
4424 previously-configured and currently unpacked or
4425 half-configured versions must satisfy any version
4426 clause in the <tt>Pre-Depends</tt> field.
4430 When the package declaring a pre-dependency is about
4431 to be <em>configured</em>, the pre-dependency will be
4432 treated as a normal <tt>Depends</tt>, that is, it will
4433 be considered satisfied only if the depended-on
4434 package has been correctly configured.
4438 <tt>Pre-Depends</tt> should be used sparingly,
4439 preferably only by packages whose premature upgrade or
4440 installation would hamper the ability of the system to
4441 continue with any upgrade that might be in progress.
4445 <tt>Pre-Depends</tt> are also required if the
4446 <prgn>preinst</prgn> script depends on the named
4447 package. It is best to avoid this situation if
4455 When selecting which level of dependency to use you should
4456 consider how important the depended-on package is to the
4457 functionality of the one declaring the dependency. Some
4458 packages are composed of components of varying degrees of
4459 importance. Such a package should list using
4460 <tt>Depends</tt> the package(s) which are required by the
4461 more important components. The other components'
4462 requirements may be mentioned as Suggestions or
4463 Recommendations, as appropriate to the components' relative
4469 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4472 When one binary package declares that it breaks another,
4473 <prgn>dpkg</prgn> will refuse to allow the package which
4474 declares <tt>Breaks</tt> be installed unless the broken
4475 package is deconfigured first, and it will refuse to
4476 allow the broken package to be reconfigured.
4480 A package will not be regarded as causing breakage merely
4481 because its configuration files are still installed; it must
4482 be at least half-installed.
4486 A special exception is made for packages which declare that
4487 they break their own package name or a virtual package which
4488 they provide (see below): this does not count as a real
4493 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4494 version clause; such a <tt>Breaks</tt> is introduced in the
4495 version of an (implicit or explicit) dependency which
4496 violates an assumption or reveals a bug in earlier versions
4497 of the broken package. This use of <tt>Breaks</tt> will
4498 inform higher-level package management tools that broken
4499 package must be upgraded before the new one.
4503 If the breaking package also overwrites some files from the
4504 older package, it should use <tt>Replaces</tt> (not
4505 <tt>Conflicts</tt>) to ensure this goes smoothly.
4509 <sect id="conflicts">
4510 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4513 When one binary package declares a conflict with another
4514 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4515 refuse to allow them to be installed on the system at the
4520 If one package is to be installed, the other must be removed
4521 first - if the package being installed is marked as
4522 replacing (see <ref id="replaces">) the one on the system,
4523 or the one on the system is marked as deselected, or both
4524 packages are marked <tt>Essential</tt>, then
4525 <prgn>dpkg</prgn> will automatically remove the package
4526 which is causing the conflict, otherwise it will halt the
4527 installation of the new package with an error. This
4528 mechanism is specifically designed to produce an error when
4529 the installed package is <tt>Essential</tt>, but the new
4534 A package will not cause a conflict merely because its
4535 configuration files are still installed; it must be at least
4540 A special exception is made for packages which declare a
4541 conflict with their own package name, or with a virtual
4542 package which they provide (see below): this does not
4543 prevent their installation, and allows a package to conflict
4544 with others providing a replacement for it. You use this
4545 feature when you want the package in question to be the only
4546 package providing some feature.
4550 A <tt>Conflicts</tt> entry should almost never have an
4551 "earlier than" version clause. This would prevent
4552 <prgn>dpkg</prgn> from upgrading or installing the package
4553 which declared such a conflict until the upgrade or removal
4554 of the conflicted-with package had been completed. Instead,
4555 <tt>Breaks</tt> may be used.
4559 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4563 As well as the names of actual ("concrete") packages, the
4564 package relationship fields <tt>Depends</tt>,
4565 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4566 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4567 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4568 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4569 may mention "virtual packages".
4573 A <em>virtual package</em> is one which appears in the
4574 <tt>Provides</tt> control file field of another package.
4575 The effect is as if the package(s) which provide a
4576 particular virtual package name had been listed by name
4577 everywhere the virtual package name appears. (See also <ref
4582 If there are both concrete and virtual packages of the same
4583 name, then the dependency may be satisfied (or the conflict
4584 caused) by either the concrete package with the name in
4585 question or any other concrete package which provides the
4586 virtual package with the name in question. This is so that,
4587 for example, supposing we have
4588 <example compact="compact">
4591 </example> and someone else releases an enhanced version of
4592 the <tt>bar</tt> package they can say:
4593 <example compact="compact">
4597 and the <tt>bar-plus</tt> package will now also satisfy the
4598 dependency for the <tt>foo</tt> package.
4602 If a relationship field has a version number attached
4603 then only real packages will be considered to see whether
4604 the relationship is satisfied (or the prohibition violated,
4605 for a conflict or breakage) - it is assumed that a real
4606 package which provides the virtual package is not of the
4607 "right" version. So, a <tt>Provides</tt> field may not
4608 contain version numbers, and the version number of the
4609 concrete package which provides a particular virtual package
4610 will not be looked at when considering a dependency on or
4611 conflict with the virtual package name.
4615 It is likely that the ability will be added in a future
4616 release of <prgn>dpkg</prgn> to specify a version number for
4617 each virtual package it provides. This feature is not yet
4618 present, however, and is expected to be used only
4623 If you want to specify which of a set of real packages
4624 should be the default to satisfy a particular dependency on
4625 a virtual package, you should list the real package as an
4626 alternative before the virtual one.
4631 <sect id="replaces"><heading>Overwriting files and replacing
4632 packages - <tt>Replaces</tt></heading>
4635 Packages can declare in their control file that they should
4636 overwrite files in certain other packages, or completely
4637 replace other packages. The <tt>Replaces</tt> control file
4638 field has these two distinct purposes.
4641 <sect1><heading>Overwriting files in other packages</heading>
4644 Firstly, as mentioned before, it is usually an error for a
4645 package to contain files which are on the system in
4650 However, if the overwriting package declares that it
4651 <tt>Replaces</tt> the one containing the file being
4652 overwritten, then <prgn>dpkg</prgn> will replace the file
4653 from the old package with that from the new. The file
4654 will no longer be listed as "owned" by the old package.
4658 If a package is completely replaced in this way, so that
4659 <prgn>dpkg</prgn> does not know of any files it still
4660 contains, it is considered to have "disappeared". It will
4661 be marked as not wanted on the system (selected for
4662 removal) and not installed. Any <tt>conffile</tt>s
4663 details noted for the package will be ignored, as they
4664 will have been taken over by the overwriting package. The
4665 package's <prgn>postrm</prgn> script will be run with a
4666 special argument to allow the package to do any final
4667 cleanup required. See <ref id="mscriptsinstact">.
4670 Replaces is a one way relationship -- you have to
4671 install the replacing package after the replaced
4678 For this usage of <tt>Replaces</tt>, virtual packages (see
4679 <ref id="virtual">) are not considered when looking at a
4680 <tt>Replaces</tt> field - the packages declared as being
4681 replaced must be mentioned by their real names.
4685 Furthermore, this usage of <tt>Replaces</tt> only takes
4686 effect when both packages are at least partially on the
4687 system at once, so that it can only happen if they do not
4688 conflict or if the conflict has been overridden.
4693 <sect1><heading>Replacing whole packages, forcing their
4697 Secondly, <tt>Replaces</tt> allows the packaging system to
4698 resolve which package should be removed when there is a
4699 conflict - see <ref id="conflicts">. This usage only
4700 takes effect when the two packages <em>do</em> conflict,
4701 so that the two usages of this field do not interfere with
4706 In this situation, the package declared as being replaced
4707 can be a virtual package, so for example, all mail
4708 transport agents (MTAs) would have the following fields in
4709 their control files:
4710 <example compact="compact">
4711 Provides: mail-transport-agent
4712 Conflicts: mail-transport-agent
4713 Replaces: mail-transport-agent
4715 ensuring that only one MTA can be installed at any one
4720 <sect id="sourcebinarydeps">
4721 <heading>Relationships between source and binary packages -
4722 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4723 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4727 Source packages that require certain binary packages to be
4728 installed or absent at the time of building the package
4729 can declare relationships to those binary packages.
4733 This is done using the <tt>Build-Depends</tt>,
4734 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4735 <tt>Build-Conflicts-Indep</tt> control file fields.
4739 Build-dependencies on "build-essential" binary packages can be
4740 omitted. Please see <ref id="pkg-relations"> for more information.
4744 The dependencies and conflicts they define must be satisfied
4745 (as defined earlier for binary packages) in order to invoke
4746 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4748 If you make "build-arch" or "binary-arch", you need
4749 Build-Depends. If you make "build-indep" or
4750 "binary-indep", you need Build-Depends and
4751 Build-Depends-Indep. If you make "build" or "binary",
4755 There is no Build-Depends-Arch; this role is essentially
4756 met with Build-Depends. Anyone building the
4757 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4758 is basically assumed to be building the whole package
4759 anyway and so installs all build dependencies. The
4760 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4761 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4762 does not yet know how to check for its existence) and
4763 <tt>binary-arch</tt>.
4766 The purpose of the original split, I recall, was so that
4767 the autobuilders wouldn't need to install extra packages
4768 needed only for the binary-indep targets. But without a
4769 build-arch/build-indep split, this didn't work, since
4770 most of the work is done in the build target, not in the
4776 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4778 The <tt>Build-Depends</tt> and
4779 <tt>Build-Conflicts</tt> fields must be satisfied when
4780 any of the following targets is invoked:
4781 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4782 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4783 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4785 <tag><tt>Build-Depends-Indep</tt>,
4786 <tt>Build-Conflicts-Indep</tt></tag>
4788 The <tt>Build-Depends-Indep</tt> and
4789 <tt>Build-Conflicts-Indep</tt> fields must be
4790 satisfied when any of the following targets is
4791 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4792 <tt>binary</tt> and <tt>binary-indep</tt>.
4802 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4805 Packages containing shared libraries must be constructed with
4806 a little care to make sure that the shared library is always
4807 available. This is especially important for packages whose
4808 shared libraries are vitally important, such as the C library
4809 (currently <tt>libc6</tt>).
4813 Packages involving shared libraries should be split up into
4814 several binary packages. This section mostly deals with how
4815 this separation is to be accomplished; rules for files within
4816 the shared library packages are in <ref id="libraries"> instead.
4819 <sect id="sharedlibs-runtime">
4820 <heading>Run-time shared libraries</heading>
4823 The run-time shared library needs to be placed in a package
4824 whose name changes whenever the shared object version
4827 Since it is common place to install several versions of a
4828 package that just provides shared libraries, it is a
4829 good idea that the library package should not
4830 contain any extraneous non-versioned files, unless they
4831 happen to be in versioned directories.</p>
4833 The most common mechanism is to place it in a package
4835 <package><var>libraryname</var><var>soversion</var></package>,
4836 where <file><var>soversion</var></file> is the version number
4837 in the soname of the shared library<footnote>
4838 The soname is the shared object name: it's the thing
4839 that has to match exactly between building an executable
4840 and running it for the dynamic linker to be able run the
4841 program. For example, if the soname of the library is
4842 <file>libfoo.so.6</file>, the library package would be
4843 called <file>libfoo6</file>.
4845 Alternatively, if it would be confusing to directly append
4846 <var>soversion</var> to <var>libraryname</var> (e.g. because
4847 <var>libraryname</var> itself ends in a number), you may use
4848 <package><var>libraryname</var>-<var>soversion</var></package> and
4849 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4854 If you have several shared libraries built from the same
4855 source tree you may lump them all together into a single
4856 shared library package, provided that you change all of
4857 their sonames at once (so that you don't get filename
4858 clashes if you try to install different versions of the
4859 combined shared libraries package).
4863 The package should install the shared libraries under
4864 their normal names. For example, the <package>libgdbm3</package>
4865 package should install <file>libgdbm.so.3.0.0</file> as
4866 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4867 renamed or re-linked by any <prgn>prerm</prgn> or
4868 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4869 of renaming things safely without affecting running programs,
4870 and attempts to interfere with this are likely to lead to
4875 Shared libraries should not be installed executable, since
4876 the dynamic linker does not require this and trying to
4877 execute a shared library usually results in a core dump.
4881 The run-time library package should include the symbolic link that
4882 <prgn>ldconfig</prgn> would create for the shared libraries.
4883 For example, the <package>libgdbm3</package> package should include
4884 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4885 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4886 linker (for example <prgn>ld.so</prgn> or
4887 <prgn>ld-linux.so.*</prgn>) can find the library between the
4888 time that <prgn>dpkg</prgn> installs it and the time that
4889 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4891 The package management system requires the library to be
4892 placed before the symbolic link pointing to it in the
4893 <file>.deb</file> file. This is so that when
4894 <prgn>dpkg</prgn> comes to install the symlink
4895 (overwriting the previous symlink pointing at an older
4896 version of the library), the new shared library is already
4897 in place. In the past, this was achieved by creating the
4898 library in the temporary packaging directory before
4899 creating the symlink. Unfortunately, this was not always
4900 effective, since the building of the tar file in the
4901 <file>.deb</file> depended on the behavior of the underlying
4902 file system. Some file systems (such as reiserfs) reorder
4903 the files so that the order of creation is forgotten.
4904 Since version 1.7.0, <prgn>dpkg</prgn>
4905 reorders the files itself as necessary when building a
4906 package. Thus it is no longer important to concern
4907 oneself with the order of file creation.
4911 <sect1 id="ldconfig">
4912 <heading><tt>ldconfig</tt></heading>
4915 Any package installing shared libraries in one of the default
4916 library directories of the dynamic linker (which are currently
4917 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4918 listed in <file>/etc/ld.so.conf</file><footnote>
4920 <list compact="compact">
4921 <item>/usr/local/lib</item>
4922 <item>/usr/lib/libc5-compat</item>
4923 <item>/lib/libc5-compat</item>
4926 must use <prgn>ldconfig</prgn> to update the shared library
4931 The package maintainer scripts must only call
4932 <prgn>ldconfig</prgn> under these circumstances:
4933 <list compact="compact">
4934 <item>When the <prgn>postinst</prgn> script is run with a
4935 first argument of <tt>configure</tt>, the script must call
4936 <prgn>ldconfig</prgn>, and may optionally invoke
4937 <prgn>ldconfig</prgn> at other times.
4939 <item>When the <prgn>postrm</prgn> script is run with a
4940 first argument of <tt>remove</tt>, the script should call
4941 <prgn>ldconfig</prgn>.
4946 During install or upgrade, the preinst is called before
4947 the new files are installed, so calling "ldconfig" is
4948 pointless. The preinst of an existing package can also be
4949 called if an upgrade fails. However, this happens during
4950 the critical time when a shared libs may exist on-disk
4951 under a temporary name. Thus, it is dangerous and
4952 forbidden by current policy to call "ldconfig" at this
4957 When a package is installed or upgraded, "postinst
4958 configure" runs after the new files are safely on-disk.
4959 Since it is perfectly safe to invoke ldconfig
4960 unconditionally in a postinst, it is OK for a package to
4961 simply put ldconfig in its postinst without checking the
4962 argument. The postinst can also be called to recover from
4963 a failed upgrade. This happens before any new files are
4964 unpacked, so there is no reason to call "ldconfig" at this
4969 For a package that is being removed, prerm is
4970 called with all the files intact, so calling ldconfig is
4971 useless. The other calls to "prerm" happen in the case of
4972 upgrade at a time when all the files of the old package
4973 are on-disk, so again calling "ldconfig" is pointless.
4977 postrm, on the other hand, is called with the "remove"
4978 argument just after the files are removed, so this is
4979 the proper time to call "ldconfig" to notify the system
4980 of the fact that the shared libraries from the package
4981 are removed. The postrm can be called at several other
4982 times. At the time of "postrm purge", "postrm
4983 abort-install", or "postrm abort-upgrade", calling
4984 "ldconfig" is useless because the shared lib files are
4985 not on-disk. However, when "postrm" is invoked with
4986 arguments "upgrade", "failed-upgrade", or "disappear", a
4987 shared lib may exist on-disk under a temporary filename.
4995 <sect id="sharedlibs-support-files">
4996 <heading>Shared library support files</heading>
4999 If your package contains files whose names do not change with
5000 each change in the library shared object version, you must not
5001 put them in the shared library package. Otherwise, several
5002 versions of the shared library cannot be installed at the same
5003 time without filename clashes, making upgrades and transitions
5004 unnecessarily difficult.
5008 It is recommended that supporting files and run-time support
5009 programs that do not need to be invoked manually by users, but
5010 are nevertheless required for the package to function, be placed
5011 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5012 preferably under <file>/usr/lib/</file><var>package-name</var>.
5013 If the program or file is architecture independent, the
5014 recommendation is for it to be placed in a subdirectory of
5015 <file>/usr/share</file> instead, preferably under
5016 <file>/usr/share/</file><var>package-name</var>. Following the
5017 <var>package-name</var> naming convention ensures that the file
5018 names change when the shared object version changes.
5022 Run-time support programs that use the shared library but are
5023 not required for the library to function or files used by the
5024 shared library that can be used by any version of the shared
5025 library package should instead be put in a separate package.
5026 This package might typically be named
5027 <package><var>libraryname</var>-tools</package>; note the
5028 absence of the <var>soversion</var> in the package name.
5032 Files and support programs only useful when compiling software
5033 against the library should be included in the development
5034 package for the library.<footnote>
5035 For example, a <file><var>package-name</var>-config</file>
5036 script or <package>pkg-config</package> configuration files.
5041 <sect id="sharedlibs-static">
5042 <heading>Static libraries</heading>
5045 The static library (<file><var>libraryname.a</var></file>)
5046 is usually provided in addition to the shared version.
5047 It is placed into the development package (see below).
5051 In some cases, it is acceptable for a library to be
5052 available in static form only; these cases include:
5054 <item>libraries for languages whose shared library support
5055 is immature or unstable</item>
5056 <item>libraries whose interfaces are in flux or under
5057 development (commonly the case when the library's
5058 major version number is zero, or where the ABI breaks
5059 across patchlevels)</item>
5060 <item>libraries which are explicitly intended to be
5061 available only in static form by their upstream
5066 <sect id="sharedlibs-dev">
5067 <heading>Development files</heading>
5070 The development files associated to a shared library need to be
5071 placed in a package called
5072 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5073 or if you prefer only to support one development version at a
5074 time, <package><var>libraryname</var>-dev</package>.
5078 In case several development versions of a library exist, you may
5079 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5080 <ref id="conflicts">) to ensure that the user only installs one
5081 development version at a time (as different development versions are
5082 likely to have the same header files in them, which would cause a
5083 filename clash if both were installed).
5087 The development package should contain a symlink for the associated
5088 shared library without a version number. For example, the
5089 <package>libgdbm-dev</package> package should include a symlink
5090 from <file>/usr/lib/libgdbm.so</file> to
5091 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5092 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5093 <file>libgdbm.so</file> when compiling dynamically.
5097 <sect id="sharedlibs-intradeps">
5098 <heading>Dependencies between the packages of the same library</heading>
5101 Typically the development version should have an exact
5102 version dependency on the runtime library, to make sure that
5103 compilation and linking happens correctly. The
5104 <tt>${binary:Version}</tt> substitution variable can be
5105 useful for this purpose.
5107 Previously, <tt>${Source-Version}</tt> was used, but its name
5108 was confusing and it has been deprecated since dpkg 1.13.19.
5113 <sect id="sharedlibs-shlibdeps">
5114 <heading>Dependencies between the library and other packages -
5115 the <tt>shlibs</tt> system</heading>
5118 If a package contains a binary or library which links to a
5119 shared library, we must ensure that when the package is
5120 installed on the system, all of the libraries needed are
5121 also installed. This requirement led to the creation of the
5122 <tt>shlibs</tt> system, which is very simple in its design:
5123 any package which <em>provides</em> a shared library also
5124 provides information on the package dependencies required to
5125 ensure the presence of this library, and any package which
5126 <em>uses</em> a shared library uses this information to
5127 determine the dependencies it requires. The files which
5128 contain the mapping from shared libraries to the necessary
5129 dependency information are called <file>shlibs</file> files.
5133 Thus, when a package is built which contains any shared
5134 libraries, it must provide a <file>shlibs</file> file for other
5135 packages to use, and when a package is built which contains
5136 any shared libraries or compiled binaries, it must run
5137 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5138 on these to determine the libraries used and hence the
5139 dependencies needed by this package.<footnote>
5141 In the past, the shared libraries linked to were
5142 determined by calling <prgn>ldd</prgn>, but now
5143 <prgn>objdump</prgn> is used to do this. The only
5144 change this makes to package building is that
5145 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5146 libraries, whereas in the past this was unnecessary.
5147 The rest of this footnote explains the advantage that
5152 We say that a binary <tt>foo</tt> <em>directly</em> uses
5153 a library <tt>libbar</tt> if it is explicitly linked
5154 with that library (that is, it uses the flag
5155 <tt>-lbar</tt> during the linking stage). Other
5156 libraries that are needed by <tt>libbar</tt> are linked
5157 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5158 linker will load them automatically when it loads
5159 <tt>libbar</tt>. A package should depend on
5160 the libraries it directly uses, and the dependencies for
5161 those libraries should automatically pull in the other
5166 Unfortunately, the <prgn>ldd</prgn> program shows both
5167 the directly and indirectly used libraries, meaning that
5168 the dependencies determined included both direct and
5169 indirect dependencies. The use of <prgn>objdump</prgn>
5170 avoids this problem by determining only the directly
5175 A good example of where this helps is the following. We
5176 could update <tt>libimlib</tt> with a new version that
5177 supports a new graphics format called dgf (but retaining
5178 the same major version number). If we used the old
5179 <prgn>ldd</prgn> method, every package that uses
5180 <tt>libimlib</tt> would need to be recompiled so it
5181 would also depend on <tt>libdgf</tt> or it wouldn't run
5182 due to missing symbols. However with the new system,
5183 packages using <tt>libimlib</tt> can rely on
5184 <tt>libimlib</tt> itself having the dependency on
5185 <tt>libdgf</tt> and so they would not need rebuilding.
5191 In the following sections, we will first describe where the
5192 various <tt>shlibs</tt> files are to be found, then how to
5193 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5194 file format and how to create them if your package contains a
5199 <heading>The <tt>shlibs</tt> files present on the system</heading>
5202 There are several places where <tt>shlibs</tt> files are
5203 found. The following list gives them in the order in which
5205 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5206 (The first one which gives the required information is used.)
5212 <p><file>debian/shlibs.local</file></p>
5215 This lists overrides for this package. Its use is
5216 described below (see <ref id="shlibslocal">).
5221 <p><file>/etc/dpkg/shlibs.override</file></p>
5224 This lists global overrides. This list is normally
5225 empty. It is maintained by the local system
5231 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5234 When packages are being built, any
5235 <file>debian/shlibs</file> files are copied into the
5236 control file area of the temporary build directory and
5237 given the name <file>shlibs</file>. These files give
5238 details of any shared libraries included in the
5240 An example may help here. Let us say that the
5241 source package <tt>foo</tt> generates two binary
5242 packages, <tt>libfoo2</tt> and
5243 <tt>foo-runtime</tt>. When building the binary
5244 packages, the two packages are created in the
5245 directories <file>debian/libfoo2</file> and
5246 <file>debian/foo-runtime</file> respectively.
5247 (<file>debian/tmp</file> could be used instead of one
5248 of these.) Since <tt>libfoo2</tt> provides the
5249 <tt>libfoo</tt> shared library, it will require a
5250 <tt>shlibs</tt> file, which will be installed in
5251 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5253 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5254 when <prgn>dpkg-shlibdeps</prgn> is run on the
5256 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5258 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5259 determine whether <tt>foo-prog</tt>'s library
5260 dependencies are satisfied by any of the libraries
5261 provided by <tt>libfoo2</tt>. For this reason,
5262 <prgn>dpkg-shlibdeps</prgn> must only be run once
5263 all of the individual binary packages'
5264 <tt>shlibs</tt> files have been installed into the
5271 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5274 These are the <file>shlibs</file> files corresponding to
5275 all of the packages installed on the system, and are
5276 maintained by the relevant package maintainers.
5281 <p><file>/etc/dpkg/shlibs.default</file></p>
5284 This file lists any shared libraries whose packages
5285 have failed to provide correct <file>shlibs</file> files.
5286 It was used when the <file>shlibs</file> setup was first
5287 introduced, but it is now normally empty. It is
5288 maintained by the <tt>dpkg</tt> maintainer.
5296 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5297 <file>shlibs</file> files</heading>
5301 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5302 into your <file>debian/rules</file> file. If your package
5303 contains only compiled binaries and libraries (but no scripts),
5304 you can use a command such as:
5305 <example compact="compact">
5306 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5307 debian/tmp/usr/lib/*
5309 Otherwise, you will need to explicitly list the compiled
5310 binaries and libraries.<footnote>
5311 If you are using <tt>debhelper</tt>, the
5312 <prgn>dh_shlibdeps</prgn> program will do this work for
5313 you. It will also correctly handle multi-binary
5319 This command puts the dependency information into the
5320 <file>debian/substvars</file> file, which is then used by
5321 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5322 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5323 field in the control file for this to work.
5327 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5328 done. If it does complain you might need to create your own
5329 <file>debian/shlibs.local</file> file, as explained below (see
5330 <ref id="shlibslocal">).
5334 If you have multiple binary packages, you will need to call
5335 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5336 compiled libraries or binaries. In such a case, you will
5337 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5338 utilities to specify a different <file>substvars</file> file.
5342 If you are creating a udeb for use in the Debian Installer,
5343 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5344 should use the dependency line of type <tt>udeb</tt> by
5345 adding the <tt>-tudeb</tt> option<footnote>
5346 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5347 will automatically add this option if it knows it is
5349 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5350 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5351 fall back to the regular dependency line.
5355 For more details on dpkg-shlibdeps, please see
5356 <ref id="pkg-dpkg-shlibdeps"> and
5357 <manref name="dpkg-shlibdeps" section="1">.
5362 <heading>The <file>shlibs</file> File Format</heading>
5365 Each <file>shlibs</file> file has the same format. Lines
5366 beginning with <tt>#</tt> are considered to be comments and
5367 are ignored. Each line is of the form:
5368 <example compact="compact">
5369 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5374 We will explain this by reference to the example of the
5375 <tt>zlib1g</tt> package, which (at the time of writing)
5376 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5380 <var>type</var> is an optional element that indicates the type
5381 of package for which the line is valid. The only type currently
5382 in use is <tt>udeb</tt>. The colon and space after the type are
5387 <var>library-name</var> is the name of the shared library,
5388 in this case <tt>libz</tt>. (This must match the name part
5389 of the soname, see below.)
5393 <var>soname-version</var> is the version part of the soname of
5394 the library. The soname is the thing that must exactly match
5395 for the library to be recognized by the dynamic linker, and is
5397 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5398 example, <tt>libz.so.1</tt>.<footnote>
5399 This can be determined using the command
5400 <example compact="compact">
5401 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5404 The version part is the part which comes after
5405 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5409 <var>dependencies</var> has the same syntax as a dependency
5410 field in a binary package control file. It should give
5411 details of which packages are required to satisfy a binary
5412 built against the version of the library contained in the
5413 package. See <ref id="depsyntax"> for details.
5417 In our example, if the first version of the <tt>zlib1g</tt>
5418 package which contained a minor number of at least
5419 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5420 <tt>shlibs</tt> entry for this library could say:
5421 <example compact="compact">
5422 libz 1 zlib1g (>= 1:1.1.3)
5424 The version-specific dependency is to avoid warnings from
5425 the dynamic linker about using older shared libraries with
5430 As zlib1g also provides a udeb containing the shared library,
5431 there would also be a second line:
5432 <example compact="compact">
5433 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5439 <heading>Providing a <file>shlibs</file> file</heading>
5442 If your package provides a shared library, you need to create
5443 a <file>shlibs</file> file following the format described above.
5444 It is usual to call this file <file>debian/shlibs</file> (but if
5445 you have multiple binary packages, you might want to call it
5446 <file>debian/shlibs.<var>package</var></file> instead). Then
5447 let <file>debian/rules</file> install it in the control area:
5448 <example compact="compact">
5449 install -m644 debian/shlibs debian/tmp/DEBIAN
5451 or, in the case of a multi-binary package:
5452 <example compact="compact">
5453 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5455 An alternative way of doing this is to create the
5456 <file>shlibs</file> file in the control area directly from
5457 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5458 file at all,<footnote>
5459 This is what <prgn>dh_makeshlibs</prgn> in the
5460 <tt>debhelper</tt> suite does. If your package also has a udeb
5461 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5462 automatically generate the <tt>udeb:</tt> lines if you specify
5463 the name of the udeb with the <tt>--add-udeb</tt> option.
5465 since the <file>debian/shlibs</file> file itself is ignored by
5466 <prgn>dpkg-shlibdeps</prgn>.
5470 As <prgn>dpkg-shlibdeps</prgn> reads the
5471 <file>DEBIAN/shlibs</file> files in all of the binary packages
5472 being built from this source package, all of the
5473 <file>DEBIAN/shlibs</file> files should be installed before
5474 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5479 <sect1 id="shlibslocal">
5480 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5483 This file is intended only as a <em>temporary</em> fix if
5484 your binaries or libraries depend on a library whose package
5485 does not yet provide a correct <file>shlibs</file> file.
5489 We will assume that you are trying to package a binary
5490 <tt>foo</tt>. When you try running
5491 <prgn>dpkg-shlibdeps</prgn> you get the following error
5492 message (<tt>-O</tt> displays the dependency information on
5493 <tt>stdout</tt> instead of writing it to
5494 <tt>debian/substvars</tt>, and the lines have been wrapped
5495 for ease of reading):
5496 <example compact="compact">
5497 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5498 dpkg-shlibdeps: warning: unable to find dependency
5499 information for shared library libbar (soname 1,
5500 path /usr/lib/libbar.so.1, dependency field Depends)
5501 shlibs:Depends=libc6 (>= 2.2.2-2)
5503 You can then run <prgn>ldd</prgn> on the binary to find the
5504 full location of the library concerned:
5505 <example compact="compact">
5507 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5508 libc.so.6 => /lib/libc.so.6 (0x40032000)
5509 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5511 So the <prgn>foo</prgn> binary depends on the
5512 <prgn>libbar</prgn> shared library, but no package seems to
5513 provide a <file>*.shlibs</file> file handling
5514 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5515 determine the package responsible:
5516 <example compact="compact">
5517 $ dpkg -S /usr/lib/libbar.so.1
5518 bar1: /usr/lib/libbar.so.1
5519 $ dpkg -s bar1 | grep Version
5522 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5523 is the one we are using. Now we can file a bug against the
5524 <tt>bar1</tt> package and create our own
5525 <file>debian/shlibs.local</file> to locally fix the problem.
5526 Including the following line into your
5527 <file>debian/shlibs.local</file> file:
5528 <example compact="compact">
5529 libbar 1 bar1 (>= 1.0-1)
5531 should allow the package build to work.
5535 As soon as the maintainer of <tt>bar1</tt> provides a
5536 correct <file>shlibs</file> file, you should remove this line
5537 from your <file>debian/shlibs.local</file> file. (You should
5538 probably also then have a versioned <tt>Build-Depends</tt>
5539 on <tt>bar1</tt> to help ensure that others do not have the
5540 same problem building your package.)
5549 <chapt id="opersys"><heading>The Operating System</heading>
5552 <heading>File system hierarchy</heading>
5556 <heading>File System Structure</heading>
5559 The location of all installed files and directories must
5560 comply with the Filesystem Hierarchy Standard (FHS),
5561 version 2.3, with the exceptions noted below, and except
5562 where doing so would violate other terms of Debian
5563 Policy. The following exceptions to the FHS apply:
5568 The optional rules related to user specific
5569 configuration files for applications are stored in
5570 the user's home directory are relaxed. It is
5571 recommended that such files start with the
5572 '<tt>.</tt>' character (a "dot file"), and if an
5573 application needs to create more than one dot file
5574 then the preferred placement is in a subdirectory
5575 with a name starting with a '.' character, (a "dot
5576 directory"). In this case it is recommended the
5577 configuration files not start with the '.'
5583 The requirement for amd64 to use <file>/lib64</file>
5584 for 64 bit binaries is removed.
5589 The requirement for object files, internal binaries, and
5590 libraries, including <file>libc.so.*</file>, to be located
5591 directly under <file>/lib{,32}</file> and
5592 <file>/usr/lib{,32}</file> is amended, permitting files
5593 to instead be installed to
5594 <file>/lib/<var>triplet</var></file> and
5595 <file>/usr/lib/<var>triplet</var></file>, where
5596 <tt><var>triplet</var></tt> is the value returned by
5597 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5598 architecture of the package. Packages may <em>not</em>
5599 install files to any <var>triplet</var> path other
5600 than the one matching the architecture of that package;
5601 for instance, an <tt>Architecture: amd64</tt> package
5602 containing 32-bit x86 libraries may not install these
5603 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5605 This is necessary in order to reserve the directories for
5606 use in cross-installation of library packages from other
5607 architectures, as part of the planned deployment of
5612 Applications may also use a single subdirectory under
5613 <file>/usr/lib/<var>triplet</var></file>.
5616 The execution time linker/loader, ld*, must still be made
5617 available in the existing location under /lib or /lib64
5618 since this is part of the ELF ABI for the architecture.
5623 The requirement that
5624 <file>/usr/local/share/man</file> be "synonymous"
5625 with <file>/usr/local/man</file> is relaxed to a
5630 The requirement that windowmanagers with a single
5631 configuration file call it <file>system.*wmrc</file>
5632 is removed, as is the restriction that the window
5633 manager subdirectory be named identically to the
5634 window manager name itself.
5639 The requirement that boot manager configuration
5640 files live in <file>/etc</file>, or at least are
5641 symlinked there, is relaxed to a recommendation.
5646 The following directories in the root filesystem are
5647 additionally allowed: <file>/sys</file> and
5648 <file>/selinux</file>. <footnote>These directories
5649 are used as mount points to mount virtual filesystems
5650 to get access to kernel information.</footnote>
5657 The version of this document referred here can be
5658 found in the <tt>debian-policy</tt> package or on <url
5659 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5660 name="FHS (Debian copy)"> alongside this manual (or, if
5661 you have the <package>debian-policy</package> installed,
5663 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5664 (local copy)">). The
5665 latest version, which may be a more recent version, may
5667 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5668 Specific questions about following the standard may be
5669 asked on the <tt>debian-devel</tt> mailing list, or
5670 referred to the FHS mailing list (see the
5671 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5677 <heading>Site-specific programs</heading>
5680 As mandated by the FHS, packages must not place any
5681 files in <file>/usr/local</file>, either by putting them in
5682 the file system archive to be unpacked by <prgn>dpkg</prgn>
5683 or by manipulating them in their maintainer scripts.
5687 However, the package may create empty directories below
5688 <file>/usr/local</file> so that the system administrator knows
5689 where to place site-specific files. These are not
5690 directories <em>in</em> <file>/usr/local</file>, but are
5691 children of directories in <file>/usr/local</file>. These
5692 directories (<file>/usr/local/*/dir/</file>)
5693 should be removed on package removal if they are
5698 Note that this applies only to
5699 directories <em>below</em> <file>/usr/local</file>,
5700 not <em>in</em> <file>/usr/local</file>. Packages must
5701 not create sub-directories in the
5702 directory <file>/usr/local</file> itself, except those
5703 listed in FHS, section 4.5. However, you may create
5704 directories below them as you wish. You must not remove
5705 any of the directories listed in 4.5, even if you created
5710 Since <file>/usr/local</file> can be mounted read-only from a
5711 remote server, these directories must be created and
5712 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5713 maintainer scripts and not be included in the
5714 <file>.deb</file> archive. These scripts must not fail if
5715 either of these operations fail.
5719 For example, the <tt>emacsen-common</tt> package could
5720 contain something like
5721 <example compact="compact">
5722 if [ ! -e /usr/local/share/emacs ]
5724 if mkdir /usr/local/share/emacs 2>/dev/null
5726 chown root:staff /usr/local/share/emacs
5727 chmod 2775 /usr/local/share/emacs
5731 in its <prgn>postinst</prgn> script, and
5732 <example compact="compact">
5733 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5734 rmdir /usr/local/share/emacs 2>/dev/null || true
5736 in the <prgn>prerm</prgn> script. (Note that this form is
5737 used to ensure that if the script is interrupted, the
5738 directory <file>/usr/local/share/emacs</file> will still be
5743 If you do create a directory in <file>/usr/local</file> for
5744 local additions to a package, you should ensure that
5745 settings in <file>/usr/local</file> take precedence over the
5746 equivalents in <file>/usr</file>.
5750 However, because <file>/usr/local</file> and its contents are
5751 for exclusive use of the local administrator, a package
5752 must not rely on the presence or absence of files or
5753 directories in <file>/usr/local</file> for normal operation.
5757 The <file>/usr/local</file> directory itself and all the
5758 subdirectories created by the package should (by default) have
5759 permissions 2775 (group-writable and set-group-id) and be
5760 owned by <tt>root:staff</tt>.
5765 <heading>The system-wide mail directory</heading>
5767 The system-wide mail directory
5768 is <file>/var/mail</file>. This directory is part of the
5769 base system and should not be owned by any particular mail
5770 agents. The use of the old
5771 location <file>/var/spool/mail</file> is deprecated, even
5772 though the spool may still be physically located there.
5778 <heading>Users and groups</heading>
5781 <heading>Introduction</heading>
5783 The Debian system can be configured to use either plain or
5788 Some user ids (UIDs) and group ids (GIDs) are reserved
5789 globally for use by certain packages. Because some
5790 packages need to include files which are owned by these
5791 users or groups, or need the ids compiled into binaries,
5792 these ids must be used on any Debian system only for the
5793 purpose for which they are allocated. This is a serious
5794 restriction, and we should avoid getting in the way of
5795 local administration policies. In particular, many sites
5796 allocate users and/or local system groups starting at 100.
5800 Apart from this we should have dynamically allocated ids,
5801 which should by default be arranged in some sensible
5802 order, but the behavior should be configurable.
5806 Packages other than <tt>base-passwd</tt> must not modify
5807 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5808 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5813 <heading>UID and GID classes</heading>
5815 The UID and GID numbers are divided into classes as
5821 Globally allocated by the Debian project, the same
5822 on every Debian system. These ids will appear in
5823 the <file>passwd</file> and <file>group</file> files of all
5824 Debian systems, new ids in this range being added
5825 automatically as the <tt>base-passwd</tt> package is
5830 Packages which need a single statically allocated
5831 uid or gid should use one of these; their
5832 maintainers should ask the <tt>base-passwd</tt>
5840 Dynamically allocated system users and groups.
5841 Packages which need a user or group, but can have
5842 this user or group allocated dynamically and
5843 differently on each system, should use <tt>adduser
5844 --system</tt> to create the group and/or user.
5845 <prgn>adduser</prgn> will check for the existence of
5846 the user or group, and if necessary choose an unused
5847 id based on the ranges specified in
5848 <file>adduser.conf</file>.
5852 <tag>1000-29999:</tag>
5855 Dynamically allocated user accounts. By default
5856 <prgn>adduser</prgn> will choose UIDs and GIDs for
5857 user accounts in this range, though
5858 <file>adduser.conf</file> may be used to modify this
5863 <tag>30000-59999:</tag>
5868 <tag>60000-64999:</tag>
5871 Globally allocated by the Debian project, but only
5872 created on demand. The ids are allocated centrally
5873 and statically, but the actual accounts are only
5874 created on users' systems on demand.
5878 These ids are for packages which are obscure or
5879 which require many statically-allocated ids. These
5880 packages should check for and create the accounts in
5881 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5882 <prgn>adduser</prgn> if it has this facility) if
5883 necessary. Packages which are likely to require
5884 further allocations should have a "hole" left after
5885 them in the allocation, to give them room to
5890 <tag>65000-65533:</tag>
5898 User <tt>nobody</tt>. The corresponding gid refers
5899 to the group <tt>nogroup</tt>.
5906 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5907 not</em> be used, because it is the error return
5916 <sect id="sysvinit">
5917 <heading>System run levels and <file>init.d</file> scripts</heading>
5919 <sect1 id="/etc/init.d">
5920 <heading>Introduction</heading>
5923 The <file>/etc/init.d</file> directory contains the scripts
5924 executed by <prgn>init</prgn> at boot time and when the
5925 init state (or "runlevel") is changed (see <manref
5926 name="init" section="8">).
5930 There are at least two different, yet functionally
5931 equivalent, ways of handling these scripts. For the sake
5932 of simplicity, this document describes only the symbolic
5933 link method. However, it must not be assumed by maintainer
5934 scripts that this method is being used, and any automated
5935 manipulation of the various runlevel behaviors by
5936 maintainer scripts must be performed using
5937 <prgn>update-rc.d</prgn> as described below and not by
5938 manually installing or removing symlinks. For information
5939 on the implementation details of the other method,
5940 implemented in the <tt>file-rc</tt> package, please refer
5941 to the documentation of that package.
5945 These scripts are referenced by symbolic links in the
5946 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5947 runlevels, <prgn>init</prgn> looks in the directory
5948 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5949 execute, where <tt><var>n</var></tt> is the runlevel that
5950 is being changed to, or <tt>S</tt> for the boot-up
5955 The names of the links all have the form
5956 <file>S<var>mm</var><var>script</var></file> or
5957 <file>K<var>mm</var><var>script</var></file> where
5958 <var>mm</var> is a two-digit number and <var>script</var>
5959 is the name of the script (this should be the same as the
5960 name of the actual script in <file>/etc/init.d</file>).
5964 When <prgn>init</prgn> changes runlevel first the targets
5965 of the links whose names start with a <tt>K</tt> are
5966 executed, each with the single argument <tt>stop</tt>,
5967 followed by the scripts prefixed with an <tt>S</tt>, each
5968 with the single argument <tt>start</tt>. (The links are
5969 those in the <file>/etc/rc<var>n</var>.d</file> directory
5970 corresponding to the new runlevel.) The <tt>K</tt> links
5971 are responsible for killing services and the <tt>S</tt>
5972 link for starting services upon entering the runlevel.
5976 For example, if we are changing from runlevel 2 to
5977 runlevel 3, init will first execute all of the <tt>K</tt>
5978 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5979 all of the <tt>S</tt> prefixed scripts in that directory.
5980 The links starting with <tt>K</tt> will cause the
5981 referred-to file to be executed with an argument of
5982 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5987 The two-digit number <var>mm</var> is used to determine
5988 the order in which to run the scripts: low-numbered links
5989 have their scripts run first. For example, the
5990 <tt>K20</tt> scripts will be executed before the
5991 <tt>K30</tt> scripts. This is used when a certain service
5992 must be started before another. For example, the name
5993 server <prgn>bind</prgn> might need to be started before
5994 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5995 can set up its access lists. In this case, the script
5996 that starts <prgn>bind</prgn> would have a lower number
5997 than the script that starts <prgn>inn</prgn> so that it
5999 <example compact="compact">
6006 The two runlevels 0 (halt) and 6 (reboot) are slightly
6007 different. In these runlevels, the links with an
6008 <tt>S</tt> prefix are still called after those with a
6009 <tt>K</tt> prefix, but they too are called with the single
6010 argument <tt>stop</tt>.
6015 <heading>Writing the scripts</heading>
6018 Packages that include daemons for system services should
6019 place scripts in <file>/etc/init.d</file> to start or stop
6020 services at boot time or during a change of runlevel.
6021 These scripts should be named
6022 <file>/etc/init.d/<var>package</var></file>, and they should
6023 accept one argument, saying what to do:
6026 <tag><tt>start</tt></tag>
6027 <item>start the service,</item>
6029 <tag><tt>stop</tt></tag>
6030 <item>stop the service,</item>
6032 <tag><tt>restart</tt></tag>
6033 <item>stop and restart the service if it's already running,
6034 otherwise start the service</item>
6036 <tag><tt>reload</tt></tag>
6037 <item><p>cause the configuration of the service to be
6038 reloaded without actually stopping and restarting
6041 <tag><tt>force-reload</tt></tag>
6042 <item>cause the configuration to be reloaded if the
6043 service supports this, otherwise restart the
6047 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6048 <tt>force-reload</tt> options should be supported by all
6049 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6054 The <file>init.d</file> scripts must ensure that they will
6055 behave sensibly (i.e., returning success and not starting
6056 multiple copies of a service) if invoked with <tt>start</tt>
6057 when the service is already running, or with <tt>stop</tt>
6058 when it isn't, and that they don't kill unfortunately-named
6059 user processes. The best way to achieve this is usually to
6060 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6065 If a service reloads its configuration automatically (as
6066 in the case of <prgn>cron</prgn>, for example), the
6067 <tt>reload</tt> option of the <file>init.d</file> script
6068 should behave as if the configuration has been reloaded
6073 The <file>/etc/init.d</file> scripts must be treated as
6074 configuration files, either (if they are present in the
6075 package, that is, in the .deb file) by marking them as
6076 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6077 by managing them correctly in the maintainer scripts (see
6078 <ref id="config-files">). This is important since we want
6079 to give the local system administrator the chance to adapt
6080 the scripts to the local system, e.g., to disable a
6081 service without de-installing the package, or to specify
6082 some special command line options when starting a service,
6083 while making sure their changes aren't lost during the next
6088 These scripts should not fail obscurely when the
6089 configuration files remain but the package has been
6090 removed, as configuration files remain on the system after
6091 the package has been removed. Only when <prgn>dpkg</prgn>
6092 is executed with the <tt>--purge</tt> option will
6093 configuration files be removed. In particular, as the
6094 <file>/etc/init.d/<var>package</var></file> script itself is
6095 usually a <tt>conffile</tt>, it will remain on the system
6096 if the package is removed but not purged. Therefore, you
6097 should include a <tt>test</tt> statement at the top of the
6099 <example compact="compact">
6100 test -f <var>program-executed-later-in-script</var> || exit 0
6105 Often there are some variables in the <file>init.d</file>
6106 scripts whose values control the behavior of the scripts,
6107 and which a system administrator is likely to want to
6108 change. As the scripts themselves are frequently
6109 <tt>conffile</tt>s, modifying them requires that the
6110 administrator merge in their changes each time the package
6111 is upgraded and the <tt>conffile</tt> changes. To ease
6112 the burden on the system administrator, such configurable
6113 values should not be placed directly in the script.
6114 Instead, they should be placed in a file in
6115 <file>/etc/default</file>, which typically will have the same
6116 base name as the <file>init.d</file> script. This extra file
6117 should be sourced by the script when the script runs. It
6118 must contain only variable settings and comments in SUSv3
6119 <prgn>sh</prgn> format. It may either be a
6120 <tt>conffile</tt> or a configuration file maintained by
6121 the package maintainer scripts. See <ref id="config-files">
6126 To ensure that vital configurable values are always
6127 available, the <file>init.d</file> script should set default
6128 values for each of the shell variables it uses, either
6129 before sourcing the <file>/etc/default/</file> file or
6130 afterwards using something like the <tt>:
6131 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6132 script must behave sensibly and not fail if the
6133 <file>/etc/default</file> file is deleted.
6137 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6138 as temporary filesystems<footnote>
6139 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6140 options in <file>/etc/default/rcS</file>.
6141 </footnote>, so the <file>init.d</file> scripts must handle this
6142 correctly. This will typically amount to creating any required
6143 subdirectories dynamically when the <file>init.d</file> script
6144 is run, rather than including them in the package and relying on
6145 <prgn>dpkg</prgn> to create them.
6150 <heading>Interfacing with the initscript system</heading>
6153 Maintainers should use the abstraction layer provided by
6154 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6155 programs to deal with initscripts in their packages'
6156 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6157 and <prgn>postrm</prgn>.
6161 Directly managing the /etc/rc?.d links and directly
6162 invoking the <file>/etc/init.d/</file> initscripts should
6163 be done only by packages providing the initscript
6164 subsystem (such as <prgn>sysv-rc</prgn> and
6165 <prgn>file-rc</prgn>).
6169 <heading>Managing the links</heading>
6172 The program <prgn>update-rc.d</prgn> is provided for
6173 package maintainers to arrange for the proper creation and
6174 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6175 or their functional equivalent if another method is being
6176 used. This may be used by maintainers in their packages'
6177 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6181 You must not include any <file>/etc/rc<var>n</var>.d</file>
6182 symbolic links in the actual archive or manually create or
6183 remove the symbolic links in maintainer scripts; you must
6184 use the <prgn>update-rc.d</prgn> program instead. (The
6185 former will fail if an alternative method of maintaining
6186 runlevel information is being used.) You must not include
6187 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6188 in the archive either. (Only the <tt>sysvinit</tt>
6193 By default <prgn>update-rc.d</prgn> will start services in
6194 each of the multi-user state runlevels (2, 3, 4, and 5)
6195 and stop them in the halt runlevel (0), the single-user
6196 runlevel (1) and the reboot runlevel (6). The system
6197 administrator will have the opportunity to customize
6198 runlevels by simply adding, moving, or removing the
6199 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6200 symbolic links are being used, or by modifying
6201 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6206 To get the default behavior for your package, put in your
6207 <prgn>postinst</prgn> script
6208 <example compact="compact">
6209 update-rc.d <var>package</var> defaults
6211 and in your <prgn>postrm</prgn>
6212 <example compact="compact">
6213 if [ "$1" = purge ]; then
6214 update-rc.d <var>package</var> remove
6216 </example>. Note that if your package changes runlevels
6217 or priority, you may have to remove and recreate the links,
6218 since otherwise the old links may persist. Refer to the
6219 documentation of <prgn>update-rc.d</prgn>.
6223 This will use a default sequence number of 20. If it does
6224 not matter when or in which order the <file>init.d</file>
6225 script is run, use this default. If it does, then you
6226 should talk to the maintainer of the <prgn>sysvinit</prgn>
6227 package or post to <tt>debian-devel</tt>, and they will
6228 help you choose a number.
6232 For more information about using <tt>update-rc.d</tt>,
6233 please consult its man page <manref name="update-rc.d"
6239 <heading>Running initscripts</heading>
6241 The program <prgn>invoke-rc.d</prgn> is provided to make
6242 it easier for package maintainers to properly invoke an
6243 initscript, obeying runlevel and other locally-defined
6244 constraints that might limit a package's right to start,
6245 stop and otherwise manage services. This program may be
6246 used by maintainers in their packages' scripts.
6250 The package maintainer scripts must use
6251 <prgn>invoke-rc.d</prgn> to invoke the
6252 <file>/etc/init.d/*</file> initscripts, instead of
6253 calling them directly.
6257 By default, <prgn>invoke-rc.d</prgn> will pass any
6258 action requests (start, stop, reload, restart...) to the
6259 <file>/etc/init.d</file> script, filtering out requests
6260 to start or restart a service out of its intended
6265 Most packages will simply need to change:
6266 <example compact="compact">/etc/init.d/<package>
6267 <action></example> in their <prgn>postinst</prgn>
6268 and <prgn>prerm</prgn> scripts to:
6269 <example compact="compact">
6270 if which invoke-rc.d >/dev/null 2>&1; then
6271 invoke-rc.d <var>package</var> <action>
6273 /etc/init.d/<var>package</var> <action>
6279 A package should register its initscript services using
6280 <prgn>update-rc.d</prgn> before it tries to invoke them
6281 using <prgn>invoke-rc.d</prgn>. Invocation of
6282 unregistered services may fail.
6286 For more information about using
6287 <prgn>invoke-rc.d</prgn>, please consult its man page
6288 <manref name="invoke-rc.d" section="8">.
6294 <heading>Boot-time initialization</heading>
6297 There used to be another directory, <file>/etc/rc.boot</file>,
6298 which contained scripts which were run once per machine
6299 boot. This has been deprecated in favour of links from
6300 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6301 described in <ref id="/etc/init.d">. Packages must not
6302 place files in <file>/etc/rc.boot</file>.
6307 <heading>Example</heading>
6310 An example on which you can base your
6311 <file>/etc/init.d</file> scripts is found in
6312 <file>/etc/init.d/skeleton</file>.
6319 <heading>Console messages from <file>init.d</file> scripts</heading>
6322 This section describes the formats to be used for messages
6323 written to standard output by the <file>/etc/init.d</file>
6324 scripts. The intent is to improve the consistency of
6325 Debian's startup and shutdown look and feel. For this
6326 reason, please look very carefully at the details. We want
6327 the messages to have the same format in terms of wording,
6328 spaces, punctuation and case of letters.
6332 Here is a list of overall rules that should be used for
6333 messages generated by <file>/etc/init.d</file> scripts.
6339 The message should fit in one line (fewer than 80
6340 characters), start with a capital letter and end with
6341 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6345 If the script is performing some time consuming task in
6346 the background (not merely starting or stopping a
6347 program, for instance), an ellipsis (three dots:
6348 <tt>...</tt>) should be output to the screen, with no
6349 leading or tailing whitespace or line feeds.
6353 The messages should appear as if the computer is telling
6354 the user what it is doing (politely :-), but should not
6355 mention "it" directly. For example, instead of:
6356 <example compact="compact">
6357 I'm starting network daemons: nfsd mountd.
6359 the message should say
6360 <example compact="compact">
6361 Starting network daemons: nfsd mountd.
6368 <tt>init.d</tt> script should use the following standard
6369 message formats for the situations enumerated below.
6375 <p>When daemons are started</p>
6378 If the script starts one or more daemons, the output
6379 should look like this (a single line, no leading
6381 <example compact="compact">
6382 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6384 The <var>description</var> should describe the
6385 subsystem the daemon or set of daemons are part of,
6386 while <var>daemon-1</var> up to <var>daemon-n</var>
6387 denote each daemon's name (typically the file name of
6392 For example, the output of <file>/etc/init.d/lpd</file>
6394 <example compact="compact">
6395 Starting printer spooler: lpd.
6400 This can be achieved by saying
6401 <example compact="compact">
6402 echo -n "Starting printer spooler: lpd"
6403 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6406 in the script. If there are more than one daemon to
6407 start, the output should look like this:
6408 <example compact="compact">
6409 echo -n "Starting remote file system services:"
6410 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6411 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6412 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6415 This makes it possible for the user to see what is
6416 happening and when the final daemon has been started.
6417 Care should be taken in the placement of white spaces:
6418 in the example above the system administrators can
6419 easily comment out a line if they don't want to start
6420 a specific daemon, while the displayed message still
6426 <p>When a system parameter is being set</p>
6429 If you have to set up different system parameters
6430 during the system boot, you should use this format:
6431 <example compact="compact">
6432 Setting <var>parameter</var> to "<var>value</var>".
6437 You can use a statement such as the following to get
6439 <example compact="compact">
6440 echo "Setting DNS domainname to \"$domainname\"."
6445 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6446 for the left and right quotation marks. A grave accent
6447 (<tt>`</tt>) is not a quote character; neither is an
6448 apostrophe (<tt>'</tt>).
6453 <p>When a daemon is stopped or restarted</p>
6456 When you stop or restart a daemon, you should issue a
6457 message identical to the startup message, except that
6458 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6459 or <tt>Restarting</tt> respectively.
6463 For example, stopping the printer daemon will look like
6465 <example compact="compact">
6466 Stopping printer spooler: lpd.
6472 <p>When something is executed</p>
6475 There are several examples where you have to run a
6476 program at system startup or shutdown to perform a
6477 specific task, for example, setting the system's clock
6478 using <prgn>netdate</prgn> or killing all processes
6479 when the system shuts down. Your message should look
6481 <example compact="compact">
6482 Doing something very useful...done.
6484 You should print the <tt>done.</tt> immediately after
6485 the job has been completed, so that the user is
6486 informed why they have to wait. You can get this
6488 <example compact="compact">
6489 echo -n "Doing something very useful..."
6498 <p>When the configuration is reloaded</p>
6501 When a daemon is forced to reload its configuration
6502 files you should use the following format:
6503 <example compact="compact">
6504 Reloading <var>description</var> configuration...done.
6506 where <var>description</var> is the same as in the
6507 daemon starting message.
6515 <heading>Cron jobs</heading>
6518 Packages must not modify the configuration file
6519 <file>/etc/crontab</file>, and they must not modify the files in
6520 <file>/var/spool/cron/crontabs</file>.</p>
6523 If a package wants to install a job that has to be executed
6524 via cron, it should place a file with the name of the
6525 package in one or more of the following directories:
6526 <example compact="compact">
6532 As these directory names imply, the files within them are
6533 executed on an hourly, daily, weekly, or monthly basis,
6534 respectively. The exact times are listed in
6535 <file>/etc/crontab</file>.</p>
6538 All files installed in any of these directories must be
6539 scripts (e.g., shell scripts or Perl scripts) so that they
6540 can easily be modified by the local system administrator.
6541 In addition, they must be treated as configuration files.
6545 If a certain job has to be executed at some other frequency or
6546 at a specific time, the package should install a file
6547 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6548 same syntax as <file>/etc/crontab</file> and is processed by
6549 <prgn>cron</prgn> automatically. The file must also be
6550 treated as a configuration file. (Note that entries in the
6551 <file>/etc/cron.d</file> directory are not handled by
6552 <prgn>anacron</prgn>. Thus, you should only use this
6553 directory for jobs which may be skipped if the system is not
6557 The scripts or crontab entries in these directories should
6558 check if all necessary programs are installed before they
6559 try to execute them. Otherwise, problems will arise when a
6560 package was removed but not purged since configuration files
6561 are kept on the system in this situation.</p>
6565 <heading>Menus</heading>
6568 The Debian <tt>menu</tt> package provides a standard
6569 interface between packages providing applications and
6570 <em>menu programs</em> (either X window managers or
6571 text-based menu programs such as <prgn>pdmenu</prgn>).
6575 All packages that provide applications that need not be
6576 passed any special command line arguments for normal
6577 operation should register a menu entry for those
6578 applications, so that users of the <tt>menu</tt> package
6579 will automatically get menu entries in their window
6580 managers, as well in shells like <tt>pdmenu</tt>.
6584 Menu entries should follow the current menu policy.
6588 The menu policy can be found in the <tt>menu-policy</tt>
6589 files in the <tt>debian-policy</tt> package.
6590 It is also available from the Debian web mirrors at
6591 <tt><url name="/doc/packaging-manuals/menu-policy/"
6592 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6596 Please also refer to the <em>Debian Menu System</em>
6597 documentation that comes with the <package>menu</package>
6598 package for information about how to register your
6604 <heading>Multimedia handlers</heading>
6607 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6608 is a mechanism for encoding files and data streams and
6609 providing meta-information about them, in particular their
6610 type (e.g. audio or video) and format (e.g. PNG, HTML,
6615 Registration of MIME type handlers allows programs like mail
6616 user agents and web browsers to invoke these handlers to
6617 view, edit or display MIME types they don't support directly.
6621 Packages which provide the ability to view/show/play,
6622 compose, edit or print MIME types should register themselves
6623 as such following the current MIME support policy.
6627 The MIME support policy can be found in the <tt>mime-policy</tt>
6628 files in the <tt>debian-policy</tt> package.
6629 It is also available from the Debian web mirrors at
6630 <tt><url name="/doc/packaging-manuals/mime-policy/"
6631 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6637 <heading>Keyboard configuration</heading>
6640 To achieve a consistent keyboard configuration so that all
6641 applications interpret a keyboard event the same way, all
6642 programs in the Debian distribution must be configured to
6643 comply with the following guidelines.
6647 The following keys must have the specified interpretations:
6650 <tag><tt><--</tt></tag>
6651 <item>delete the character to the left of the cursor</item>
6653 <tag><tt>Delete</tt></tag>
6654 <item>delete the character to the right of the cursor</item>
6656 <tag><tt>Control+H</tt></tag>
6657 <item>emacs: the help prefix</item>
6660 The interpretation of any keyboard events should be
6661 independent of the terminal that is used, be it a virtual
6662 console, an X terminal emulator, an rlogin/telnet session,
6667 The following list explains how the different programs
6668 should be set up to achieve this:
6674 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6678 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6682 X translations are set up to make
6683 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6684 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6685 is the vt220 escape code for the "delete character"
6686 key). This must be done by loading the X resources
6687 using <prgn>xrdb</prgn> on all local X displays, not
6688 using the application defaults, so that the
6689 translation resources used correspond to the
6690 <prgn>xmodmap</prgn> settings.
6694 The Linux console is configured to make
6695 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6696 generate <tt>ESC [ 3 ~</tt>.
6700 X applications are configured so that <tt><</tt>
6701 deletes left, and <tt>Delete</tt> deletes right. Motif
6702 applications already work like this.
6706 Terminals should have <tt>stty erase ^?</tt> .
6710 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6711 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6712 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6716 Emacs is programmed to map <tt>KB_Backspace</tt> or
6717 the <tt>stty erase</tt> character to
6718 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6719 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6720 <tt>^H</tt> to <tt>help</tt> as always.
6724 Other applications use the <tt>stty erase</tt>
6725 character and <tt>kdch1</tt> for the two delete keys,
6726 with ASCII DEL being "delete previous character" and
6727 <tt>kdch1</tt> being "delete character under
6735 This will solve the problem except for the following
6742 Some terminals have a <tt><--</tt> key that cannot
6743 be made to produce anything except <tt>^H</tt>. On
6744 these terminals Emacs help will be unavailable on
6745 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6746 character takes precedence in Emacs, and has been set
6747 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6748 available) can be used instead.
6752 Some operating systems use <tt>^H</tt> for <tt>stty
6753 erase</tt>. However, modern telnet versions and all
6754 rlogin versions propagate <tt>stty</tt> settings, and
6755 almost all UNIX versions honour <tt>stty erase</tt>.
6756 Where the <tt>stty</tt> settings are not propagated
6757 correctly, things can be made to work by using
6758 <tt>stty</tt> manually.
6762 Some systems (including previous Debian versions) use
6763 <prgn>xmodmap</prgn> to arrange for both
6764 <tt><--</tt> and <tt>Delete</tt> to generate
6765 <tt>KB_Delete</tt>. We can change the behavior of
6766 their X clients using the same X resources that we use
6767 to do it for our own clients, or configure our clients
6768 using their resources when things are the other way
6769 around. On displays configured like this
6770 <tt>Delete</tt> will not work, but <tt><--</tt>
6775 Some operating systems have different <tt>kdch1</tt>
6776 settings in their <tt>terminfo</tt> database for
6777 <tt>xterm</tt> and others. On these systems the
6778 <tt>Delete</tt> key will not work correctly when you
6779 log in from a system conforming to our policy, but
6780 <tt><--</tt> will.
6787 <heading>Environment variables</heading>
6790 A program must not depend on environment variables to get
6791 reasonable defaults. (That's because these environment
6792 variables would have to be set in a system-wide
6793 configuration file like <file>/etc/profile</file>, which is not
6794 supported by all shells.)
6798 If a program usually depends on environment variables for its
6799 configuration, the program should be changed to fall back to
6800 a reasonable default configuration if these environment
6801 variables are not present. If this cannot be done easily
6802 (e.g., if the source code of a non-free program is not
6803 available), the program must be replaced by a small
6804 "wrapper" shell script which sets the environment variables
6805 if they are not already defined, and calls the original program.
6809 Here is an example of a wrapper script for this purpose:
6811 <example compact="compact">
6813 BAR=${BAR:-/var/lib/fubar}
6815 exec /usr/lib/foo/foo "$@"
6820 Furthermore, as <file>/etc/profile</file> is a configuration
6821 file of the <prgn>base-files</prgn> package, other packages must
6822 not put any environment variables or other commands into that
6827 <sect id="doc-base">
6828 <heading>Registering Documents using doc-base</heading>
6831 The <package>doc-base</package> package implements a
6832 flexible mechanism for handling and presenting
6833 documentation. The recommended practice is for every Debian
6834 package that provides online documentation (other than just
6835 manual pages) to register these documents with
6836 <package>doc-base</package> by installing a
6837 <package>doc-base</package> control file via the
6838 <prgn/install-docs/ script at installation time and
6839 de-register the manuals again when the package is removed.
6842 Please refer to the documentation that comes with the
6843 <package>doc-base</package> package for information and
6852 <heading>Files</heading>
6855 <heading>Binaries</heading>
6858 Two different packages must not install programs with
6859 different functionality but with the same filenames. (The
6860 case of two programs having the same functionality but
6861 different implementations is handled via "alternatives" or
6862 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6863 <ref id="conflicts"> respectively.) If this case happens,
6864 one of the programs must be renamed. The maintainers should
6865 report this to the <tt>debian-devel</tt> mailing list and
6866 try to find a consensus about which program will have to be
6867 renamed. If a consensus cannot be reached, <em>both</em>
6868 programs must be renamed.
6872 By default, when a package is being built, any binaries
6873 created should include debugging information, as well as
6874 being compiled with optimization. You should also turn on
6875 as many reasonable compilation warnings as possible; this
6876 makes life easier for porters, who can then look at build
6877 logs for possible problems. For the C programming language,
6878 this means the following compilation parameters should be
6880 <example compact="compact">
6882 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6884 INSTALL = install -s # (or use strip on the files in debian/tmp)
6889 Note that by default all installed binaries should be stripped,
6890 either by using the <tt>-s</tt> flag to
6891 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6892 the binaries after they have been copied into
6893 <file>debian/tmp</file> but before the tree is made into a
6898 Although binaries in the build tree should be compiled with
6899 debugging information by default, it can often be difficult to
6900 debug programs if they are also subjected to compiler
6901 optimization. For this reason, it is recommended to support the
6902 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6903 (see <ref id="debianrules-options">). This variable can contain
6904 several flags to change how a package is compiled and built.
6908 It is up to the package maintainer to decide what
6909 compilation options are best for the package. Certain
6910 binaries (such as computationally-intensive programs) will
6911 function better with certain flags (<tt>-O3</tt>, for
6912 example); feel free to use them. Please use good judgment
6913 here. Don't use flags for the sake of it; only use them
6914 if there is good reason to do so. Feel free to override
6915 the upstream author's ideas about which compilation
6916 options are best: they are often inappropriate for our
6922 <sect id="libraries">
6923 <heading>Libraries</heading>
6926 If the package is <strong>architecture: any</strong>, then
6927 the shared library compilation and linking flags must have
6928 <tt>-fPIC</tt>, or the package shall not build on some of
6929 the supported architectures<footnote>
6931 If you are using GCC, <tt>-fPIC</tt> produces code with
6932 relocatable position independent code, which is required for
6933 most architectures to create a shared library, with i386 and
6934 perhaps some others where non position independent code is
6935 permitted in a shared library.
6938 Position independent code may have a performance penalty,
6939 especially on <tt>i386</tt>. However, in most cases the
6940 speed penalty must be measured against the memory wasted on
6941 the few architectures where non position independent code is
6944 </footnote>. Any exception to this rule must be discussed on
6945 the mailing list <em>debian-devel@lists.debian.org</em>, and
6946 a rough consensus obtained. The reasons for not compiling
6947 with <tt>-fPIC</tt> flag must be recorded in the file
6948 <tt>README.Debian</tt>, and care must be taken to either
6949 restrict the architecture or arrange for <tt>-fPIC</tt> to
6950 be used on architectures where it is required.<footnote>
6952 Some of the reasons why this might be required is if the
6953 library contains hand crafted assembly code that is not
6954 relocatable, the speed penalty is excessive for compute
6955 intensive libs, and similar reasons.
6960 As to the static libraries, the common case is not to have
6961 relocatable code, since there is no benefit, unless in specific
6962 cases; therefore the static version must not be compiled
6963 with the <tt>-fPIC</tt> flag. Any exception to this rule
6964 should be discussed on the mailing list
6965 <em>debian-devel@lists.debian.org</em>, and the reasons for
6966 compiling with the <tt>-fPIC</tt> flag must be recorded in
6967 the file <tt>README.Debian</tt>. <footnote>
6969 Some of the reasons for linking static libraries with
6970 the <tt>-fPIC</tt> flag are if, for example, one needs a
6971 Perl API for a library that is under rapid development,
6972 and has an unstable API, so shared libraries are
6973 pointless at this phase of the library's development. In
6974 that case, since Perl needs a library with relocatable
6975 code, it may make sense to create a static library with
6976 relocatable code. Another reason cited is if you are
6977 distilling various libraries into a common shared
6978 library, like <tt>mklibs</tt> does in the Debian
6984 In other words, if both a shared and a static library is
6985 being built, each source unit (<tt>*.c</tt>, for example,
6986 for C files) will need to be compiled twice, for the normal
6990 You must specify the gcc option <tt>-D_REENTRANT</tt>
6991 when building a library (either static or shared) to make
6992 the library compatible with LinuxThreads.
6996 Although not enforced by the build tools, shared libraries
6997 must be linked against all libraries that they use symbols from
6998 in the same way that binaries are. This ensures the correct
6999 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7000 system and guarantees that all libraries can be safely opened
7001 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7002 option <tt>-Wl,-z,defs</tt> when building a shared library.
7003 Since this option enforces symbol resolution at build time,
7004 a missing library reference will be caught early as a fatal
7009 All installed shared libraries should be stripped with
7010 <example compact="compact">
7011 strip --strip-unneeded <var>your-lib</var>
7013 (The option <tt>--strip-unneeded</tt> makes
7014 <prgn>strip</prgn> remove only the symbols which aren't
7015 needed for relocation processing.) Shared libraries can
7016 function perfectly well when stripped, since the symbols for
7017 dynamic linking are in a separate part of the ELF object
7019 You might also want to use the options
7020 <tt>--remove-section=.comment</tt> and
7021 <tt>--remove-section=.note</tt> on both shared libraries
7022 and executables, and <tt>--strip-debug</tt> on static
7028 Note that under some circumstances it may be useful to
7029 install a shared library unstripped, for example when
7030 building a separate package to support debugging.
7034 Shared object files (often <file>.so</file> files) that are not
7035 public libraries, that is, they are not meant to be linked
7036 to by third party executables (binaries of other packages),
7037 should be installed in subdirectories of the
7038 <file>/usr/lib</file> directory. Such files are exempt from the
7039 rules that govern ordinary shared libraries, except that
7040 they must not be installed executable and should be
7042 A common example are the so-called "plug-ins",
7043 internal shared objects that are dynamically loaded by
7044 programs using <manref name="dlopen" section="3">.
7049 An ever increasing number of packages are using
7050 <prgn>libtool</prgn> to do their linking. The latest GNU
7051 libtools (>= 1.3a) can take advantage of the metadata in the
7052 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7053 files). The main advantage of <prgn>libtool</prgn>'s
7054 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7055 store and subsequently access metadata with respect to the
7056 libraries it builds. <prgn>libtool</prgn> will search for
7057 those files, which contain a lot of useful information about
7058 a library (such as library dependency information for static
7059 linking). Also, they're <em>essential</em> for programs
7060 using <tt>libltdl</tt>.<footnote>
7061 Although <prgn>libtool</prgn> is fully capable of
7062 linking against shared libraries which don't have
7063 <tt>.la</tt> files, as it is a mere shell script it can
7064 add considerably to the build time of a
7065 <prgn>libtool</prgn>-using package if that shell script
7066 has to derive all this information from first principles
7067 for each library every time it is linked. With the
7068 advent of <prgn>libtool</prgn> version 1.4 (and to a
7069 lesser extent <prgn>libtool</prgn> version 1.3), the
7070 <file>.la</file> files also store information about
7071 inter-library dependencies which cannot necessarily be
7072 derived after the <file>.la</file> file is deleted.
7077 Packages that use <prgn>libtool</prgn> to create shared
7078 libraries should include the <file>.la</file> files in the
7079 <tt>-dev</tt> package, unless the package relies on
7080 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7081 the <tt>.la</tt> files must go in the run-time library
7086 You must make sure that you use only released versions of
7087 shared libraries to build your packages; otherwise other
7088 users will not be able to run your binaries
7089 properly. Producing source packages that depend on
7090 unreleased compilers is also usually a bad
7097 <heading>Shared libraries</heading>
7099 This section has moved to <ref id="sharedlibs">.
7105 <heading>Scripts</heading>
7108 All command scripts, including the package maintainer
7109 scripts inside the package and used by <prgn>dpkg</prgn>,
7110 should have a <tt>#!</tt> line naming the shell to be used
7115 In the case of Perl scripts this should be
7116 <tt>#!/usr/bin/perl</tt>.
7120 When scripts are installed into a directory in the system
7121 PATH, the script name should not include an extension such
7122 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7123 language currently used to implement it.
7126 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7127 should almost certainly start with <tt>set -e</tt> so that
7128 errors are detected. Every script should use
7129 <tt>set -e</tt> or check the exit status of <em>every</em>
7134 Scripts may assume that <file>/bin/sh</file> implements the
7135 SUSv3 Shell Command Language<footnote>
7136 Single UNIX Specification, version 3, which is also IEEE
7137 1003.1-2004 (POSIX), and is available on the World Wide Web
7138 from <url id="http://www.unix.org/version3/online.html"
7139 name="The Open Group"> after free
7140 registration.</footnote>
7141 plus the following additional features not mandated by
7143 These features are in widespread use in the Linux community
7144 and are implemented in all of bash, dash, and ksh, the most
7145 common shells users may wish to use as <file>/bin/sh</file>.
7148 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7149 must not generate a newline.</item>
7150 <item><tt>test</tt>, if implemented as a shell built-in, must
7151 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7153 <item><tt>local</tt> to create a scoped variable must be
7154 supported, including listing multiple variables in a single
7155 local command and assigning a value to a variable at the
7156 same time as localizing it. <tt>local</tt> may or
7157 may not preserve the variable value from an outer scope if
7158 no assignment is present. Uses such as:
7162 # ... use a, b, c, d ...
7165 must be supported and must set the value of <tt>c</tt> to
7169 If a shell script requires non-SUSv3 features from the shell
7170 interpreter other than those listed above, the appropriate shell
7171 must be specified in the first line of the script (e.g.,
7172 <tt>#!/bin/bash</tt>) and the package must depend on the package
7173 providing the shell (unless the shell package is marked
7174 "Essential", as in the case of <prgn>bash</prgn>).
7178 You may wish to restrict your script to SUSv3 features plus the
7179 above set when possible so that it may use <file>/bin/sh</file>
7180 as its interpreter. If your script works with <prgn>dash</prgn>
7181 (originally called <prgn>ash</prgn>), it probably complies with
7182 the above requirements, but if you are in doubt, use
7183 <file>/bin/bash</file>.
7187 Perl scripts should check for errors when making any
7188 system calls, including <tt>open</tt>, <tt>print</tt>,
7189 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7193 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7194 scripting languages. See <em>Csh Programming Considered
7195 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7196 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7197 If an upstream package comes with <prgn>csh</prgn> scripts
7198 then you must make sure that they start with
7199 <tt>#!/bin/csh</tt> and make your package depend on the
7200 <prgn>c-shell</prgn> virtual package.
7204 Any scripts which create files in world-writeable
7205 directories (e.g., in <file>/tmp</file>) must use a
7206 mechanism which will fail atomically if a file with the same
7207 name already exists.
7211 The Debian base system provides the <prgn>tempfile</prgn>
7212 and <prgn>mktemp</prgn> utilities for use by scripts for
7219 <heading>Symbolic links</heading>
7222 In general, symbolic links within a top-level directory
7223 should be relative, and symbolic links pointing from one
7224 top-level directory into another should be absolute. (A
7225 top-level directory is a sub-directory of the root
7226 directory <file>/</file>.)
7230 In addition, symbolic links should be specified as short as
7231 possible, i.e., link targets like <file>foo/../bar</file> are
7236 Note that when creating a relative link using
7237 <prgn>ln</prgn> it is not necessary for the target of the
7238 link to exist relative to the working directory you're
7239 running <prgn>ln</prgn> from, nor is it necessary to change
7240 directory to the directory where the link is to be made.
7241 Simply include the string that should appear as the target
7242 of the link (this will be a pathname relative to the
7243 directory in which the link resides) as the first argument
7248 For example, in your <prgn>Makefile</prgn> or
7249 <file>debian/rules</file>, you can do things like:
7250 <example compact="compact">
7251 ln -fs gcc $(prefix)/bin/cc
7252 ln -fs gcc debian/tmp/usr/bin/cc
7253 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7254 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7259 A symbolic link pointing to a compressed file should always
7260 have the same file extension as the referenced file. (For
7261 example, if a file <file>foo.gz</file> is referenced by a
7262 symbolic link, the filename of the link has to end with
7263 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7268 <heading>Device files</heading>
7271 Packages must not include device files or named pipes in the
7276 If a package needs any special device files that are not
7277 included in the base system, it must call
7278 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7279 after notifying the user<footnote>
7280 This notification could be done via a (low-priority)
7281 debconf message, or an echo (printf) statement.
7286 Packages must not remove any device files in the
7287 <prgn>postrm</prgn> or any other script. This is left to the
7288 system administrator.
7292 Debian uses the serial devices
7293 <file>/dev/ttyS*</file>. Programs using the old
7294 <file>/dev/cu*</file> devices should be changed to use
7295 <file>/dev/ttyS*</file>.
7299 Named pipes needed by the package must be created in
7300 the <prgn>postinst</prgn> script<footnote>
7301 It's better to use <prgn>mkfifo</prgn> rather
7302 than <prgn>mknod</prgn> to create named pipes so that
7303 automated checks for packages incorrectly creating device
7304 files with <prgn>mknod</prgn> won't have false positives.
7305 </footnote> and removed in
7306 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7311 <sect id="config-files">
7312 <heading>Configuration files</heading>
7315 <heading>Definitions</heading>
7319 <tag>configuration file</tag>
7321 A file that affects the operation of a program, or
7322 provides site- or host-specific information, or
7323 otherwise customizes the behavior of a program.
7324 Typically, configuration files are intended to be
7325 modified by the system administrator (if needed or
7326 desired) to conform to local policy or to provide
7327 more useful site-specific behavior.
7330 <tag><tt>conffile</tt></tag>
7332 A file listed in a package's <tt>conffiles</tt>
7333 file, and is treated specially by <prgn>dpkg</prgn>
7334 (see <ref id="configdetails">).
7340 The distinction between these two is important; they are
7341 not interchangeable concepts. Almost all
7342 <tt>conffile</tt>s are configuration files, but many
7343 configuration files are not <tt>conffiles</tt>.
7347 As noted elsewhere, <file>/etc/init.d</file> scripts,
7348 <file>/etc/default</file> files, scripts installed in
7349 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7350 configuration installed in <file>/etc/cron.d</file> must be
7351 treated as configuration files. In general, any script that
7352 embeds configuration information is de-facto a configuration
7353 file and should be treated as such.
7358 <heading>Location</heading>
7361 Any configuration files created or used by your package
7362 must reside in <file>/etc</file>. If there are several,
7363 consider creating a subdirectory of <file>/etc</file>
7364 named after your package.
7368 If your package creates or uses configuration files
7369 outside of <file>/etc</file>, and it is not feasible to modify
7370 the package to use <file>/etc</file> directly, put the files
7371 in <file>/etc</file> and create symbolic links to those files
7372 from the location that the package requires.
7377 <heading>Behavior</heading>
7380 Configuration file handling must conform to the following
7382 <list compact="compact">
7384 local changes must be preserved during a package
7388 configuration files must be preserved when the
7389 package is removed, and only deleted when the
7396 The easy way to achieve this behavior is to make the
7397 configuration file a <tt>conffile</tt>. This is
7398 appropriate only if it is possible to distribute a default
7399 version that will work for most installations, although
7400 some system administrators may choose to modify it. This
7401 implies that the default version will be part of the
7402 package distribution, and must not be modified by the
7403 maintainer scripts during installation (or at any other
7408 In order to ensure that local changes are preserved
7409 correctly, no package may contain or make hard links to
7410 conffiles.<footnote>
7411 Rationale: There are two problems with hard links.
7412 The first is that some editors break the link while
7413 editing one of the files, so that the two files may
7414 unwittingly become unlinked and different. The second
7415 is that <prgn>dpkg</prgn> might break the hard link
7416 while upgrading <tt>conffile</tt>s.
7421 The other way to do it is via the maintainer scripts. In
7422 this case, the configuration file must not be listed as a
7423 <tt>conffile</tt> and must not be part of the package
7424 distribution. If the existence of a file is required for
7425 the package to be sensibly configured it is the
7426 responsibility of the package maintainer to provide
7427 maintainer scripts which correctly create, update and
7428 maintain the file and remove it on purge. (See <ref
7429 id="maintainerscripts"> for more information.) These
7430 scripts must be idempotent (i.e., must work correctly if
7431 <prgn>dpkg</prgn> needs to re-run them due to errors
7432 during installation or removal), must cope with all the
7433 variety of ways <prgn>dpkg</prgn> can call maintainer
7434 scripts, must not overwrite or otherwise mangle the user's
7435 configuration without asking, must not ask unnecessary
7436 questions (particularly during upgrades), and must
7437 otherwise be good citizens.
7441 The scripts are not required to configure every possible
7442 option for the package, but only those necessary to get
7443 the package running on a given system. Ideally the
7444 sysadmin should not have to do any configuration other
7445 than that done (semi-)automatically by the
7446 <prgn>postinst</prgn> script.
7450 A common practice is to create a script called
7451 <file><var>package</var>-configure</file> and have the
7452 package's <prgn>postinst</prgn> call it if and only if the
7453 configuration file does not already exist. In certain
7454 cases it is useful for there to be an example or template
7455 file which the maintainer scripts use. Such files should
7456 be in <file>/usr/share/<var>package</var></file> or
7457 <file>/usr/lib/<var>package</var></file> (depending on whether
7458 they are architecture-independent or not). There should
7459 be symbolic links to them from
7460 <file>/usr/share/doc/<var>package</var>/examples</file> if
7461 they are examples, and should be perfectly ordinary
7462 <prgn>dpkg</prgn>-handled files (<em>not</em>
7463 configuration files).
7467 These two styles of configuration file handling must
7468 not be mixed, for that way lies madness:
7469 <prgn>dpkg</prgn> will ask about overwriting the file
7470 every time the package is upgraded.
7475 <heading>Sharing configuration files</heading>
7478 Packages which specify the same file as a
7479 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7480 with each other. (This is an instance of the general rule
7481 about not sharing files. Note that neither alternatives
7482 nor diversions are likely to be appropriate in this case;
7483 in particular, <prgn>dpkg</prgn> does not handle diverted
7484 <tt>conffile</tt>s well.)
7488 The maintainer scripts must not alter a <tt>conffile</tt>
7489 of <em>any</em> package, including the one the scripts
7494 If two or more packages use the same configuration file
7495 and it is reasonable for both to be installed at the same
7496 time, one of these packages must be defined as
7497 <em>owner</em> of the configuration file, i.e., it will be
7498 the package which handles that file as a configuration
7499 file. Other packages that use the configuration file must
7500 depend on the owning package if they require the
7501 configuration file to operate. If the other package will
7502 use the configuration file if present, but is capable of
7503 operating without it, no dependency need be declared.
7507 If it is desirable for two or more related packages to
7508 share a configuration file <em>and</em> for all of the
7509 related packages to be able to modify that configuration
7510 file, then the following should be done:
7511 <enumlist compact="compact">
7513 One of the related packages (the "owning" package)
7514 will manage the configuration file with maintainer
7515 scripts as described in the previous section.
7518 The owning package should also provide a program
7519 that the other packages may use to modify the
7523 The related packages must use the provided program
7524 to make any desired modifications to the
7525 configuration file. They should either depend on
7526 the core package to guarantee that the configuration
7527 modifier program is available or accept gracefully
7528 that they cannot modify the configuration file if it
7529 is not. (This is in addition to the fact that the
7530 configuration file may not even be present in the
7537 Sometimes it's appropriate to create a new package which
7538 provides the basic infrastructure for the other packages
7539 and which manages the shared configuration files. (The
7540 <tt>sgml-base</tt> package is a good example.)
7545 <heading>User configuration files ("dotfiles")</heading>
7548 The files in <file>/etc/skel</file> will automatically be
7549 copied into new user accounts by <prgn>adduser</prgn>.
7550 No other program should reference the files in
7551 <file>/etc/skel</file>.
7555 Therefore, if a program needs a dotfile to exist in
7556 advance in <file>$HOME</file> to work sensibly, that dotfile
7557 should be installed in <file>/etc/skel</file> and treated as a
7562 However, programs that require dotfiles in order to
7563 operate sensibly are a bad thing, unless they do create
7564 the dotfiles themselves automatically.
7568 Furthermore, programs should be configured by the Debian
7569 default installation to behave as closely to the upstream
7570 default behavior as possible.
7574 Therefore, if a program in a Debian package needs to be
7575 configured in some way in order to operate sensibly, that
7576 should be done using a site-wide configuration file placed
7577 in <file>/etc</file>. Only if the program doesn't support a
7578 site-wide default configuration and the package maintainer
7579 doesn't have time to add it may a default per-user file be
7580 placed in <file>/etc/skel</file>.
7584 <file>/etc/skel</file> should be as empty as we can make it.
7585 This is particularly true because there is no easy (or
7586 necessarily desirable) mechanism for ensuring that the
7587 appropriate dotfiles are copied into the accounts of
7588 existing users when a package is installed.
7594 <heading>Log files</heading>
7596 Log files should usually be named
7597 <file>/var/log/<var>package</var>.log</file>. If you have many
7598 log files, or need a separate directory for permission
7599 reasons (<file>/var/log</file> is writable only by
7600 <file>root</file>), you should usually create a directory named
7601 <file>/var/log/<var>package</var></file> and place your log
7606 Log files must be rotated occasionally so that they don't
7607 grow indefinitely; the best way to do this is to drop a log
7608 rotation configuration file into the directory
7609 <file>/etc/logrotate.d</file> and use the facilities provided by
7610 logrotate.<footnote>
7612 The traditional approach to log files has been to set up
7613 <em>ad hoc</em> log rotation schemes using simple shell
7614 scripts and cron. While this approach is highly
7615 customizable, it requires quite a lot of sysadmin work.
7616 Even though the original Debian system helped a little
7617 by automatically installing a system which can be used
7618 as a template, this was deemed not enough.
7622 The use of <prgn>logrotate</prgn>, a program developed
7623 by Red Hat, is better, as it centralizes log management.
7624 It has both a configuration file
7625 (<file>/etc/logrotate.conf</file>) and a directory where
7626 packages can drop their individual log rotation
7627 configurations (<file>/etc/logrotate.d</file>).
7630 Here is a good example for a logrotate config
7631 file (for more information see <manref name="logrotate"
7633 <example compact="compact">
7634 /var/log/foo/*.log {
7639 /etc/init.d/foo force-reload
7643 This rotates all files under <file>/var/log/foo</file>, saves 12
7644 compressed generations, and forces the daemon to reload its
7645 configuration information after the log rotation.
7649 Log files should be removed when the package is
7650 purged (but not when it is only removed). This should be
7651 done by the <prgn>postrm</prgn> script when it is called
7652 with the argument <tt>purge</tt> (see <ref
7653 id="removedetails">).
7658 <heading>Permissions and owners</heading>
7661 The rules in this section are guidelines for general use.
7662 If necessary you may deviate from the details below.
7663 However, if you do so you must make sure that what is done
7664 is secure and you should try to be as consistent as possible
7665 with the rest of the system. You should probably also
7666 discuss it on <prgn>debian-devel</prgn> first.
7670 Files should be owned by <tt>root:root</tt>, and made
7671 writable only by the owner and universally readable (and
7672 executable, if appropriate), that is mode 644 or 755.
7676 Directories should be mode 755 or (for group-writability)
7677 mode 2775. The ownership of the directory should be
7678 consistent with its mode: if a directory is mode 2775, it
7679 should be owned by the group that needs write access to
7682 When a package is upgraded, and the owner or permissions
7683 of a file included in the package has changed, dpkg
7684 arranges for the ownership and permissions to be
7685 correctly set upon installation. However, this does not
7686 extend to directories; the permissions and ownership of
7687 directories already on the system does not change on
7688 install or upgrade of packages. This makes sense, since
7689 otherwise common directories like <tt>/usr</tt> would
7690 always be in flux. To correctly change permissions of a
7691 directory the package owns, explicit action is required,
7692 usually in the <tt>postinst</tt> script. Care must be
7693 taken to handle downgrades as well, in that case.
7700 Setuid and setgid executables should be mode 4755 or 2755
7701 respectively, and owned by the appropriate user or group.
7702 They should not be made unreadable (modes like 4711 or
7703 2711 or even 4111); doing so achieves no extra security,
7704 because anyone can find the binary in the freely available
7705 Debian package; it is merely inconvenient. For the same
7706 reason you should not restrict read or execute permissions
7707 on non-set-id executables.
7711 Some setuid programs need to be restricted to particular
7712 sets of users, using file permissions. In this case they
7713 should be owned by the uid to which they are set-id, and by
7714 the group which should be allowed to execute them. They
7715 should have mode 4754; again there is no point in making
7716 them unreadable to those users who must not be allowed to
7721 It is possible to arrange that the system administrator can
7722 reconfigure the package to correspond to their local
7723 security policy by changing the permissions on a binary:
7724 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7725 described below.<footnote>
7726 Ordinary files installed by <prgn>dpkg</prgn> (as
7727 opposed to <tt>conffile</tt>s and other similar objects)
7728 normally have their permissions reset to the distributed
7729 permissions when the package is reinstalled. However,
7730 the use of <prgn>dpkg-statoverride</prgn> overrides this
7731 default behavior. If you use this method, you should
7732 remember to describe <prgn>dpkg-statoverride</prgn> in
7733 the package documentation; being a relatively new
7734 addition to Debian, it is probably not yet well-known.
7736 Another method you should consider is to create a group for
7737 people allowed to use the program(s) and make any setuid
7738 executables executable only by that group.
7742 If you need to create a new user or group for your package
7743 there are two possibilities. Firstly, you may need to
7744 make some files in the binary package be owned by this
7745 user or group, or you may need to compile the user or
7746 group id (rather than just the name) into the binary
7747 (though this latter should be avoided if possible, as in
7748 this case you need a statically allocated id).</p>
7751 If you need a statically allocated id, you must ask for a
7752 user or group id from the <tt>base-passwd</tt> maintainer,
7753 and must not release the package until you have been
7754 allocated one. Once you have been allocated one you must
7755 either make the package depend on a version of the
7756 <tt>base-passwd</tt> package with the id present in
7757 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7758 your package to create the user or group itself with the
7759 correct id (using <tt>adduser</tt>) in its
7760 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7761 the <prgn>postinst</prgn> is to be preferred if it is
7762 possible, otherwise a pre-dependency will be needed on the
7763 <tt>adduser</tt> package.)
7767 On the other hand, the program might be able to determine
7768 the uid or gid from the user or group name at runtime, so
7769 that a dynamically allocated id can be used. In this case
7770 you should choose an appropriate user or group name,
7771 discussing this on <prgn>debian-devel</prgn> and checking
7772 with the <package/base-passwd/ maintainer that it is unique and that
7773 they do not wish you to use a statically allocated id
7774 instead. When this has been checked you must arrange for
7775 your package to create the user or group if necessary using
7776 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7777 <prgn>postinst</prgn> script (again, the latter is to be
7778 preferred if it is possible).
7782 Note that changing the numeric value of an id associated
7783 with a name is very difficult, and involves searching the
7784 file system for all appropriate files. You need to think
7785 carefully whether a static or dynamic id is required, since
7786 changing your mind later will cause problems.
7789 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7791 This section is not intended as policy, but as a
7792 description of the use of <prgn>dpkg-statoverride</prgn>.
7796 If a system administrator wishes to have a file (or
7797 directory or other such thing) installed with owner and
7798 permissions different from those in the distributed Debian
7799 package, they can use the <prgn>dpkg-statoverride</prgn>
7800 program to instruct <prgn>dpkg</prgn> to use the different
7801 settings every time the file is installed. Thus the
7802 package maintainer should distribute the files with their
7803 normal permissions, and leave it for the system
7804 administrator to make any desired changes. For example, a
7805 daemon which is normally required to be setuid root, but
7806 in certain situations could be used without being setuid,
7807 should be installed setuid in the <tt>.deb</tt>. Then the
7808 local system administrator can change this if they wish.
7809 If there are two standard ways of doing it, the package
7810 maintainer can use <tt>debconf</tt> to find out the
7811 preference, and call <prgn>dpkg-statoverride</prgn> in the
7812 maintainer script if necessary to accommodate the system
7813 administrator's choice. Care must be taken during
7814 upgrades to not override an existing setting.
7818 Given the above, <prgn>dpkg-statoverride</prgn> is
7819 essentially a tool for system administrators and would not
7820 normally be needed in the maintainer scripts. There is
7821 one type of situation, though, where calls to
7822 <prgn>dpkg-statoverride</prgn> would be needed in the
7823 maintainer scripts, and that involves packages which use
7824 dynamically allocated user or group ids. In such a
7825 situation, something like the following idiom can be very
7826 helpful in the package's <prgn>postinst</prgn>, where
7827 <tt>sysuser</tt> is a dynamically allocated id:
7829 for i in /usr/bin/foo /usr/sbin/bar
7831 # only do something when no setting exists
7832 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7834 #include: debconf processing, question about foo and bar
7835 if [ "$RET" = "true" ] ; then
7836 dpkg-statoverride --update --add sysuser root 4755 $i
7841 The corresponding code to remove the override when the package
7844 for i in /usr/bin/foo /usr/sbin/bar
7846 if dpkg-statoverride --list $i >/dev/null 2>&1
7848 dpkg-statoverride --remove $i
7858 <chapt id="customized-programs">
7859 <heading>Customized programs</heading>
7861 <sect id="arch-spec">
7862 <heading>Architecture specification strings</heading>
7865 If a program needs to specify an <em>architecture specification
7866 string</em> in some place, it should select one of the
7867 strings provided by <tt>dpkg-architecture -L</tt>. The
7868 strings are in the format
7869 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7870 is sometimes elided, as when the OS is Linux.<footnote>
7871 <p>Currently, the strings are:
7872 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7873 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7874 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7875 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7876 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7877 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7878 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7879 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7880 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7881 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7882 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7883 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7884 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7885 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7886 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7887 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7888 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7889 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7890 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7891 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7892 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7893 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7894 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7895 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7896 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7897 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7898 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7899 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7900 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7901 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7902 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7903 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7904 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7905 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7906 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7907 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7908 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7914 Note that we don't want to use
7915 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7916 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7917 since this would make our programs incompatible with other
7918 Linux distributions. We also don't use something like
7919 <tt><var>arch</var>-unknown-linux</tt>, since the
7920 <tt>unknown</tt> does not look very good.
7925 <heading>Daemons</heading>
7928 The configuration files <file>/etc/services</file>,
7929 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7930 by the <prgn>netbase</prgn> package and must not be modified
7935 If a package requires a new entry in one of these files, the
7936 maintainer should get in contact with the
7937 <prgn>netbase</prgn> maintainer, who will add the entries
7938 and release a new version of the <prgn>netbase</prgn>
7943 The configuration file <file>/etc/inetd.conf</file> must not be
7944 modified by the package's scripts except via the
7945 <prgn>update-inetd</prgn> script or the
7946 <file>DebianNet.pm</file> Perl module. See their documentation
7947 for details on how to add entries.
7951 If a package wants to install an example entry into
7952 <file>/etc/inetd.conf</file>, the entry must be preceded with
7953 exactly one hash character (<tt>#</tt>). Such lines are
7954 treated as "commented out by user" by the
7955 <prgn>update-inetd</prgn> script and are not changed or
7956 activated during package updates.
7961 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7965 Some programs need to create pseudo-ttys. This should be done
7966 using Unix98 ptys if the C library supports it. The resulting
7967 program must not be installed setuid root, unless that
7968 is required for other functionality.
7972 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7973 <file>/var/log/lastlog</file> must be installed writable by
7974 group <tt>utmp</tt>. Programs which need to modify those
7975 files must be installed setgid <tt>utmp</tt>.
7980 <heading>Editors and pagers</heading>
7983 Some programs have the ability to launch an editor or pager
7984 program to edit or display a text document. Since there are
7985 lots of different editors and pagers available in the Debian
7986 distribution, the system administrator and each user should
7987 have the possibility to choose their preferred editor and
7992 In addition, every program should choose a good default
7993 editor/pager if none is selected by the user or system
7998 Thus, every program that launches an editor or pager must
7999 use the EDITOR or PAGER environment variable to determine
8000 the editor or pager the user wishes to use. If these
8001 variables are not set, the programs <file>/usr/bin/editor</file>
8002 and <file>/usr/bin/pager</file> should be used, respectively.
8006 These two files are managed through the <prgn>dpkg</prgn>
8007 "alternatives" mechanism. Thus every package providing an
8008 editor or pager must call the
8009 <prgn>update-alternatives</prgn> script to register these
8014 If it is very hard to adapt a program to make use of the
8015 EDITOR or PAGER variables, that program may be configured to
8016 use <file>/usr/bin/sensible-editor</file> and
8017 <file>/usr/bin/sensible-pager</file> as the editor or pager
8018 program respectively. These are two scripts provided in the
8019 <package>sensible-utils</package> package that check the EDITOR
8020 and PAGER variables and launch the appropriate program, and fall
8021 back to <file>/usr/bin/editor</file>
8022 and <file>/usr/bin/pager</file> if the variable is not set.
8026 A program may also use the VISUAL environment variable to
8027 determine the user's choice of editor. If it exists, it
8028 should take precedence over EDITOR. This is in fact what
8029 <file>/usr/bin/sensible-editor</file> does.
8033 It is not required for a package to depend on
8034 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8035 package to provide such virtual packages.<footnote>
8036 The Debian base system already provides an editor and a
8042 <sect id="web-appl">
8043 <heading>Web servers and applications</heading>
8046 This section describes the locations and URLs that should
8047 be used by all web servers and web applications in the
8054 Cgi-bin executable files are installed in the
8056 <example compact="compact">
8057 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8059 and should be referred to as
8060 <example compact="compact">
8061 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8067 <p>Access to HTML documents</p>
8070 HTML documents for a package are stored in
8071 <file>/usr/share/doc/<var>package</var></file>
8072 and can be referred to as
8073 <example compact="compact">
8074 http://localhost/doc/<var>package</var>/<var>filename</var>
8079 The web server should restrict access to the document
8080 tree so that only clients on the same host can read
8081 the documents. If the web server does not support such
8082 access controls, then it should not provide access at
8083 all, or ask about providing access during installation.
8088 <p>Access to images</p>
8090 It is recommended that images for a package be stored
8091 in <tt>/usr/share/images/<var>package</var></tt> and
8092 may be referred to through an alias <tt>/images/</tt>
8095 http://localhost/images/<package>/<filename>
8102 <p>Web Document Root</p>
8105 Web Applications should try to avoid storing files in
8106 the Web Document Root. Instead they should use the
8107 /usr/share/doc/<var>package</var> directory for
8108 documents and register the Web Application via the
8109 <package>doc-base</package> package. If access to the
8110 web document root is unavoidable then use
8111 <example compact="compact">
8114 as the Document Root. This might be just a symbolic
8115 link to the location where the system administrator
8116 has put the real document root.
8119 <item><p>Providing httpd and/or httpd-cgi</p>
8121 All web servers should provide the virtual package
8122 <tt>httpd</tt>. If a web server has CGI support it should
8123 provide <tt>httpd-cgi</tt> additionally.
8126 All web applications which do not contain CGI scripts should
8127 depend on <tt>httpd</tt>, all those web applications which
8128 <tt>do</tt> contain CGI scripts, should depend on
8136 <sect id="mail-transport-agents">
8137 <heading>Mail transport, delivery and user agents</heading>
8140 Debian packages which process electronic mail, whether mail
8141 user agents (MUAs) or mail transport agents (MTAs), must
8142 ensure that they are compatible with the configuration
8143 decisions below. Failure to do this may result in lost
8144 mail, broken <tt>From:</tt> lines, and other serious brain
8149 The mail spool is <file>/var/mail</file> and the interface to
8150 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8151 the FHS). On older systems, the mail spool may be
8152 physically located in <file>/var/spool/mail</file>, but all
8153 access to the mail spool should be via the
8154 <file>/var/mail</file> symlink. The mail spool is part of the
8155 base system and not part of the MTA package.
8159 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8160 programs (such as IMAP daemons) must lock the mailbox in an
8161 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8162 be combined with dot locking. To avoid deadlocks, a program
8163 should use <tt>fcntl()</tt> first and dot locking after
8164 this, or alternatively implement the two locking methods in
8165 a non blocking way<footnote>
8166 If it is not possible to establish both locks, the
8167 system shouldn't wait for the second lock to be
8168 established, but remove the first lock, wait a (random)
8169 time, and start over locking again.
8170 </footnote>. Using the functions <tt>maillock</tt> and
8171 <tt>mailunlock</tt> provided by the
8172 <tt>liblockfile*</tt><footnote>
8173 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8174 to use these functions.
8175 </footnote> packages is the recommended way to realize this.
8179 Mailboxes are generally either mode 600 and owned by
8180 <var>user</var> or mode 660 and owned by
8181 <tt><var>user</var>:mail</tt><footnote>
8182 There are two traditional permission schemes for mail spools:
8183 mode 600 with all mail delivery done by processes running as
8184 the destination user, or mode 660 and owned by group mail with
8185 mail delivery done by a process running as a system user in
8186 group mail. Historically, Debian required mode 660 mail
8187 spools to enable the latter model, but that model has become
8188 increasingly uncommon and the principle of least privilege
8189 indicates that mail systems that use the first model should
8190 use permissions of 600. If delivery to programs is permitted,
8191 it's easier to keep the mail system secure if the delivery
8192 agent runs as the destination user. Debian Policy therefore
8193 permits either scheme.
8194 </footnote>. The local system administrator may choose a
8195 different permission scheme; packages should not make
8196 assumptions about the permission and ownership of mailboxes
8197 unless required (such as when creating a new mailbox). A MUA
8198 may remove a mailbox (unless it has nonstandard permissions) in
8199 which case the MTA or another MUA must recreate it if needed.
8203 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8204 be setgid mail to do the locking mentioned above (and
8205 must obviously avoid accessing other users' mailboxes
8206 using this privilege).</p>
8209 <file>/etc/aliases</file> is the source file for the system mail
8210 aliases (e.g., postmaster, usenet, etc.), it is the one
8211 which the sysadmin and <prgn>postinst</prgn> scripts may
8212 edit. After <file>/etc/aliases</file> is edited the program or
8213 human editing it must call <prgn>newaliases</prgn>. All MTA
8214 packages must come with a <prgn>newaliases</prgn> program,
8215 even if it does nothing, but older MTA packages did not do
8216 this so programs should not fail if <prgn>newaliases</prgn>
8217 cannot be found. Note that because of this, all MTA
8218 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8219 <tt>Replaces: mail-transport-agent</tt> control file
8224 The convention of writing <tt>forward to
8225 <var>address</var></tt> in the mailbox itself is not
8226 supported. Use a <tt>.forward</tt> file instead.</p>
8229 The <prgn>rmail</prgn> program used by UUCP
8230 for incoming mail should be <file>/usr/sbin/rmail</file>.
8231 Likewise, <prgn>rsmtp</prgn>, for receiving
8232 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8236 If your package needs to know what hostname to use on (for
8237 example) outgoing news and mail messages which are generated
8238 locally, you should use the file <file>/etc/mailname</file>. It
8239 will contain the portion after the username and <tt>@</tt>
8240 (at) sign for email addresses of users on the machine
8241 (followed by a newline).
8245 Such a package should check for the existence of this file
8246 when it is being configured. If it exists, it should be
8247 used without comment, although an MTA's configuration script
8248 may wish to prompt the user even if it finds that this file
8249 exists. If the file does not exist, the package should
8250 prompt the user for the value (preferably using
8251 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8252 as well as using it in the package's configuration. The
8253 prompt should make it clear that the name will not just be
8254 used by that package. For example, in this situation the
8255 <tt>inn</tt> package could say something like:
8256 <example compact="compact">
8257 Please enter the "mail name" of your system. This is the
8258 hostname portion of the address to be shown on outgoing
8259 news and mail messages. The default is
8260 <var>syshostname</var>, your system's host name. Mail
8261 name ["<var>syshostname</var>"]:
8263 where <var>syshostname</var> is the output of <tt>hostname
8269 <heading>News system configuration</heading>
8272 All the configuration files related to the NNTP (news)
8273 servers and clients should be located under
8274 <file>/etc/news</file>.</p>
8277 There are some configuration issues that apply to a number
8278 of news clients and server packages on the machine. These
8282 <tag><file>/etc/news/organization</file></tag>
8284 A string which should appear as the
8285 organization header for all messages posted
8286 by NNTP clients on the machine
8289 <tag><file>/etc/news/server</file></tag>
8291 Contains the FQDN of the upstream NNTP
8292 server, or localhost if the local machine is
8297 Other global files may be added as required for cross-package news
8304 <heading>Programs for the X Window System</heading>
8307 <heading>Providing X support and package priorities</heading>
8310 Programs that can be configured with support for the X
8311 Window System must be configured to do so and must declare
8312 any package dependencies necessary to satisfy their
8313 runtime requirements when using the X Window System. If
8314 such a package is of higher priority than the X packages
8315 on which it depends, it is required that either the
8316 X-specific components be split into a separate package, or
8317 that an alternative version of the package, which includes
8318 X support, be provided, or that the package's priority be
8324 <heading>Packages providing an X server</heading>
8327 Packages that provide an X server that, directly or
8328 indirectly, communicates with real input and display
8329 hardware should declare in their control data that they
8330 provide the virtual package <tt>xserver</tt>.<footnote>
8331 This implements current practice, and provides an
8332 actual policy for usage of the <tt>xserver</tt>
8333 virtual package which appears in the virtual packages
8334 list. In a nutshell, X servers that interface
8335 directly with the display and input hardware or via
8336 another subsystem (e.g., GGI) should provide
8337 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8338 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8344 <heading>Packages providing a terminal emulator</heading>
8347 Packages that provide a terminal emulator for the X Window
8348 System which meet the criteria listed below should declare
8349 in their control data that they provide the virtual
8350 package <tt>x-terminal-emulator</tt>. They should also
8351 register themselves as an alternative for
8352 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8357 To be an <tt>x-terminal-emulator</tt>, a program must:
8358 <list compact="compact">
8360 Be able to emulate a DEC VT100 terminal, or a
8361 compatible terminal.
8365 Support the command-line option <tt>-e
8366 <var>command</var></tt>, which creates a new
8367 terminal window<footnote>
8368 "New terminal window" does not necessarily mean
8369 a new top-level X window directly parented by
8370 the window manager; it could, if the terminal
8371 emulator application were so coded, be a new
8372 "view" in a multiple-document interface (MDI).
8374 and runs the specified <var>command</var>,
8375 interpreting the entirety of the rest of the command
8376 line as a command to pass straight to exec, in the
8377 manner that <tt>xterm</tt> does.
8381 Support the command-line option <tt>-T
8382 <var>title</var></tt>, which creates a new terminal
8383 window with the window title <var>title</var>.
8390 <heading>Packages providing a window manager</heading>
8393 Packages that provide a window manager should declare in
8394 their control data that they provide the virtual package
8395 <tt>x-window-manager</tt>. They should also register
8396 themselves as an alternative for
8397 <file>/usr/bin/x-window-manager</file>, with a priority
8398 calculated as follows:
8399 <list compact="compact">
8401 Start with a priority of 20.
8405 If the window manager supports the Debian menu
8406 system, add 20 points if this support is available
8407 in the package's default configuration (i.e., no
8408 configuration files belonging to the system or user
8409 have to be edited to activate the feature); if
8410 configuration files must be modified, add only 10
8416 If the window manager complies with <url
8417 id="http://www.freedesktop.org/Standards/wm-spec"
8418 name="The Window Manager Specification Project">,
8419 written by the <url id="http://www.freedesktop.org/"
8420 name="Free Desktop Group">, add 40 points.
8424 If the window manager permits the X session to be
8425 restarted using a <em>different</em> window manager
8426 (without killing the X server) in its default
8427 configuration, add 10 points; otherwise add none.
8434 <heading>Packages providing fonts</heading>
8437 Packages that provide fonts for the X Window
8439 For the purposes of Debian Policy, a "font for the X
8440 Window System" is one which is accessed via X protocol
8441 requests. Fonts for the Linux console, for PostScript
8442 renderer, or any other purpose, do not fit this
8443 definition. Any tool which makes such fonts available
8444 to the X Window System, however, must abide by this
8447 must do a number of things to ensure that they are both
8448 available without modification of the X or font server
8449 configuration, and that they do not corrupt files used by
8450 other font packages to register information about
8454 Fonts of any type supported by the X Window System
8455 must be in a separate binary package from any
8456 executables, libraries, or documentation (except
8457 that specific to the fonts shipped, such as their
8458 license information). If one or more of the fonts
8459 so packaged are necessary for proper operation of
8460 the package with which they are associated the font
8461 package may be Recommended; if the fonts merely
8462 provide an enhancement, a Suggests relationship may
8463 be used. Packages must not Depend on font
8465 This is because the X server may retrieve fonts
8466 from the local file system or over the network
8467 from an X font server; the Debian package system
8468 is empowered to deal only with the local
8474 BDF fonts must be converted to PCF fonts with the
8475 <prgn>bdftopcf</prgn> utility (available in the
8476 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8477 placed in a directory that corresponds to their
8479 <list compact="compact">
8481 100 dpi fonts must be placed in
8482 <file>/usr/share/fonts/X11/100dpi/</file>.
8486 75 dpi fonts must be placed in
8487 <file>/usr/share/fonts/X11/75dpi/</file>.
8491 Character-cell fonts, cursor fonts, and other
8492 low-resolution fonts must be placed in
8493 <file>/usr/share/fonts/X11/misc/</file>.
8499 Type 1 fonts must be placed in
8500 <file>/usr/share/fonts/X11/Type1/</file>. If font
8501 metric files are available, they must be placed here
8506 Subdirectories of <file>/usr/share/fonts/X11/</file>
8507 other than those listed above must be neither
8508 created nor used. (The <file>PEX</file>, <file>CID</file>,
8509 <file>Speedo</file>, and <file>cyrillic</file> directories
8510 are excepted for historical reasons, but installation of
8511 files into these directories remains discouraged.)
8515 Font packages may, instead of placing files directly
8516 in the X font directories listed above, provide
8517 symbolic links in that font directory pointing to
8518 the files' actual location in the filesystem. Such
8519 a location must comply with the FHS.
8523 Font packages should not contain both 75dpi and
8524 100dpi versions of a font. If both are available,
8525 they should be provided in separate binary packages
8526 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8527 the names of the packages containing the
8528 corresponding fonts.
8532 Fonts destined for the <file>misc</file> subdirectory
8533 should not be included in the same package as 75dpi
8534 or 100dpi fonts; instead, they should be provided in
8535 a separate package with <tt>-misc</tt> appended to
8540 Font packages must not provide the files
8541 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8542 <file>fonts.scale</file> in a font directory:
8545 <file>fonts.dir</file> files must not be provided at all.
8549 <file>fonts.alias</file> and <file>fonts.scale</file>
8550 files, if needed, should be provided in the
8552 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8553 where <var>fontdir</var> is the name of the
8555 <file>/usr/share/fonts/X11/</file> where the
8556 package's corresponding fonts are stored
8557 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8558 <var>package</var> is the name of the package
8559 that provides these fonts, and
8560 <var>extension</var> is either <tt>scale</tt>
8561 or <tt>alias</tt>, whichever corresponds to
8568 Font packages must declare a dependency on
8569 <tt>xfonts-utils</tt> in their control
8574 Font packages that provide one or more
8575 <file>fonts.scale</file> files as described above must
8576 invoke <prgn>update-fonts-scale</prgn> on each
8577 directory into which they installed fonts
8578 <em>before</em> invoking
8579 <prgn>update-fonts-dir</prgn> on that directory.
8580 This invocation must occur in both the
8581 <prgn>postinst</prgn> (for all arguments) and
8582 <prgn>postrm</prgn> (for all arguments except
8583 <tt>upgrade</tt>) scripts.
8587 Font packages that provide one or more
8588 <file>fonts.alias</file> files as described above must
8589 invoke <prgn>update-fonts-alias</prgn> on each
8590 directory into which they installed fonts. This
8591 invocation must occur in both the
8592 <prgn>postinst</prgn> (for all arguments) and
8593 <prgn>postrm</prgn> (for all arguments except
8594 <tt>upgrade</tt>) scripts.
8598 Font packages must invoke
8599 <prgn>update-fonts-dir</prgn> on each directory into
8600 which they installed fonts. This invocation must
8601 occur in both the <prgn>postinst</prgn> (for all
8602 arguments) and <prgn>postrm</prgn> (for all
8603 arguments except <tt>upgrade</tt>) scripts.
8607 Font packages must not provide alias names for the
8608 fonts they include which collide with alias names
8609 already in use by fonts already packaged.
8613 Font packages must not provide fonts with the same
8614 XLFD registry name as another font already packaged.
8620 <sect1 id="appdefaults">
8621 <heading>Application defaults files</heading>
8624 Application defaults files must be installed in the
8625 directory <file>/etc/X11/app-defaults/</file> (use of a
8626 localized subdirectory of <file>/etc/X11/</file> as described
8627 in the <em>X Toolkit Intrinsics - C Language
8628 Interface</em> manual is also permitted). They must be
8629 registered as <tt>conffile</tt>s or handled as
8630 configuration files.
8634 Customization of programs' X resources may also be
8635 supported with the provision of a file with the same name
8636 as that of the package placed in
8637 the <file>/etc/X11/Xresources/</file> directory, which
8638 must be registered as a <tt>conffile</tt> or handled as a
8639 configuration file.<footnote>
8640 Note that this mechanism is not the same as using
8641 app-defaults; app-defaults are tied to the client
8642 binary on the local file system, whereas X resources
8643 are stored in the X server and affect all connecting
8650 <heading>Installation directory issues</heading>
8653 Historically, packages using the X Window System used a
8654 separate set of installation directories from other packages.
8655 This practice has been discontinued and packages using the X
8656 Window System should now generally be installed in the same
8657 directories as any other package. Specifically, packages must
8658 not install files under the <file>/usr/X11R6/</file> directory
8659 and the <file>/usr/X11R6/</file> directory hierarchy should be
8660 regarded as obsolete.
8664 Include files previously installed under
8665 <file>/usr/X11R6/include/X11/</file> should be installed into
8666 <file>/usr/include/X11/</file>. For files previously
8667 installed into subdirectories of
8668 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8669 determine if subdirectories of <file>/usr/lib/</file> and
8670 <file>/usr/share/</file> can be used. If not, a subdirectory
8671 of <file>/usr/lib/X11/</file> should be used.
8675 Configuration files for window, display, or session managers
8676 or other applications that are tightly integrated with the X
8677 Window System may be placed in a subdirectory
8678 of <file>/etc/X11/</file> corresponding to the package name.
8679 Other X Window System applications should use
8680 the <file>/etc/</file> directory unless otherwise mandated by
8681 policy (such as for <ref id="appdefaults">).
8686 <heading>The OSF/Motif and OpenMotif libraries</heading>
8689 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8690 OpenMotif libraries</em><footnote>
8691 OSF/Motif and OpenMotif are collectively referred to as
8692 "Motif" in this policy document.
8694 should be compiled against and tested with LessTif (a free
8695 re-implementation of Motif) instead. If the maintainer
8696 judges that the program or programs do not work
8697 sufficiently well with LessTif to be distributed and
8698 supported, but do so when compiled against Motif, then two
8699 versions of the package should be created; one linked
8700 statically against Motif and with <tt>-smotif</tt>
8701 appended to the package name, and one linked dynamically
8702 against Motif and with <tt>-dmotif</tt> appended to the
8707 Both Motif-linked versions are dependent
8708 upon non-DFSG-compliant software and thus cannot be
8709 uploaded to the <em>main</em> distribution; if the
8710 software is itself DFSG-compliant it may be uploaded to
8711 the <em>contrib</em> distribution. While known existing
8712 versions of Motif permit unlimited redistribution of
8713 binaries linked against the library (whether statically or
8714 dynamically), it is the package maintainer's
8715 responsibility to determine whether this is permitted by
8716 the license of the copy of Motif in their possession.
8722 <heading>Perl programs and modules</heading>
8725 Perl programs and modules should follow the current Perl policy.
8729 The Perl policy can be found in the <tt>perl-policy</tt>
8730 files in the <tt>debian-policy</tt> package.
8731 It is also available from the Debian web mirrors at
8732 <tt><url name="/doc/packaging-manuals/perl-policy/"
8733 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8738 <heading>Emacs lisp programs</heading>
8741 Please refer to the "Debian Emacs Policy" for details of how to
8742 package emacs lisp programs.
8746 The Emacs policy is available in
8747 <file>debian-emacs-policy.gz</file> of the
8748 <package>emacsen-common</package> package.
8749 It is also available from the Debian web mirrors at
8750 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8751 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8756 <heading>Games</heading>
8759 The permissions on <file>/var/games</file> are mode 755, owner
8760 <tt>root</tt> and group <tt>root</tt>.
8764 Each game decides on its own security policy.</p>
8767 Games which require protected, privileged access to
8768 high-score files, saved games, etc., may be made
8769 set-<em>group</em>-id (mode 2755) and owned by
8770 <tt>root:games</tt>, and use files and directories with
8771 appropriate permissions (770 <tt>root:games</tt>, for
8772 example). They must not be made
8773 set-<em>user</em>-id, as this causes security problems. (If
8774 an attacker can subvert any set-user-id game they can
8775 overwrite the executable of any other, causing other players
8776 of these games to run a Trojan horse program. With a
8777 set-group-id game the attacker only gets access to less
8778 important game data, and if they can get at the other
8779 players' accounts at all it will take considerably more
8783 Some packages, for example some fortune cookie programs, are
8784 configured by the upstream authors to install with their
8785 data files or other static information made unreadable so
8786 that they can only be accessed through set-id programs
8787 provided. You should not do this in a Debian package: anyone can
8788 download the <file>.deb</file> file and read the data from it,
8789 so there is no point making the files unreadable. Not
8790 making the files unreadable also means that you don't have
8791 to make so many programs set-id, which reduces the risk of a
8795 As described in the FHS, binaries of games should be
8796 installed in the directory <file>/usr/games</file>. This also
8797 applies to games that use the X Window System. Manual pages
8798 for games (X and non-X games) should be installed in
8799 <file>/usr/share/man/man6</file>.</p>
8805 <heading>Documentation</heading>
8808 <heading>Manual pages</heading>
8811 You should install manual pages in <prgn>nroff</prgn> source
8812 form, in appropriate places under <file>/usr/share/man</file>.
8813 You should only use sections 1 to 9 (see the FHS for more
8814 details). You must not install a pre-formatted "cat page".
8818 Each program, utility, and function should have an
8819 associated manual page included in the same package. It is
8820 suggested that all configuration files also have a manual
8821 page included as well. Manual pages for protocols and other
8822 auxiliary things are optional.
8826 If no manual page is available, this is considered as a bug
8827 and should be reported to the Debian Bug Tracking System (the
8828 maintainer of the package is allowed to write this bug report
8829 themselves, if they so desire). Do not close the bug report
8830 until a proper man page is available.<footnote>
8831 It is not very hard to write a man page. See the
8832 <url id="http://www.schweikhardt.net/man_page_howto.html"
8833 name="Man-Page-HOWTO">,
8834 <manref name="man" section="7">, the examples
8835 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8836 the helper programs <prgn>help2man</prgn>, or the
8837 directory <file>/usr/share/doc/man-db/examples</file>.
8842 You may forward a complaint about a missing man page to the
8843 upstream authors, and mark the bug as forwarded in the
8844 Debian bug tracking system. Even though the GNU Project do
8845 not in general consider the lack of a man page to be a bug,
8846 we do; if they tell you that they don't consider it a bug
8847 you should leave the bug in our bug tracking system open
8852 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8856 If one man page needs to be accessible via several names it
8857 is better to use a symbolic link than the <file>.so</file>
8858 feature, but there is no need to fiddle with the relevant
8859 parts of the upstream source to change from <file>.so</file> to
8860 symlinks: don't do it unless it's easy. You should not
8861 create hard links in the manual page directories, nor put
8862 absolute filenames in <file>.so</file> directives. The filename
8863 in a <file>.so</file> in a man page should be relative to the
8864 base of the man page tree (usually
8865 <file>/usr/share/man</file>). If you do not create any links
8866 (whether symlinks, hard links, or <tt>.so</tt> directives)
8867 in the file system to the alternate names of the man page,
8868 then you should not rely on <prgn>man</prgn> finding your
8869 man page under those names based solely on the information in
8870 the man page's header.<footnote>
8871 Supporting this in <prgn>man</prgn> often requires
8872 unreasonable processing time to find a manual page or to
8873 report that none exists, and moves knowledge into man's
8874 database that would be better left in the file system.
8875 This support is therefore deprecated and will cease to
8876 be present in the future.
8881 Manual pages in locale-specific subdirectories of
8882 <file>/usr/share/man</file> should use either UTF-8 or the usual
8883 legacy encoding for that language (normally the one corresponding
8884 to the shortest relevant locale name in
8885 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8886 <file>/usr/share/man/fr</file> should use either UTF-8 or
8887 ISO-8859-1.<footnote>
8888 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8889 use. In future, all manual pages will be required to use
8895 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8896 included in the subdirectory name unless it indicates a
8897 significant difference in the language, as this excludes
8898 speakers of the language in other countries.<footnote>
8899 At the time of writing, Chinese and Portuguese are the main
8900 languages with such differences, so <file>pt_BR</file>,
8901 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8906 If a localized version of a manual page is provided, it should
8907 either be up-to-date or it should be obvious to the reader that
8908 it is outdated and the original manual page should be used
8909 instead. This can be done either by a note at the beginning of
8910 the manual page or by showing the missing or changed portions in
8911 the original language instead of the target language.
8916 <heading>Info documents</heading>
8919 Info documents should be installed in <file>/usr/share/info</file>.
8920 They should be compressed with <tt>gzip -9</tt>.
8924 The <prgn>install-info</prgn> program maintains a directory of
8925 installed info documents in <file>/usr/share/info/dir</file> for
8926 the use of info readers.<footnote>
8927 It was previously necessary for packages installing info
8928 documents to run <prgn>install-info</prgn> from maintainer
8929 scripts. This is no longer necessary. The installation
8930 system now uses dpkg triggers.
8932 This file must not be included in packages. Packages containing
8933 info documents should depend on <tt>dpkg (>= 1.15.4) |
8934 install-info</tt> to ensure that the directory file is properly
8935 rebuilt during partial upgrades from Debian 5.0 (lenny) and
8940 Info documents should contain section and directory entry
8941 information in the document for the use
8942 of <prgn>install-info</prgn>. The section should be specified
8943 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8944 space and the section of this info page. The directory entry or
8945 entries should be included between
8946 a <tt>START-INFO-DIR-ENTRY</tt> line and
8947 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8949 INFO-DIR-SECTION Individual utilities
8950 START-INFO-DIR-ENTRY
8951 * example: (example). An example info directory entry.
8954 To determine which section to use, you should look
8955 at <file>/usr/share/info/dir</file> on your system and choose
8956 the most relevant (or create a new section if none of the
8957 current sections are relevant).<footnote>
8958 Normally, info documents are generated from Texinfo source.
8959 To include this information in the generated info document, if
8960 it is absent, add commands like:
8962 @dircategory Individual utilities
8964 * example: (example). An example info directory entry.
8967 to the Texinfo source of the document and ensure that the info
8968 documents are rebuilt from source during the package build.
8974 <heading>Additional documentation</heading>
8977 Any additional documentation that comes with the package may
8978 be installed at the discretion of the package maintainer.
8979 Plain text documentation should be installed in the directory
8980 <file>/usr/share/doc/<var>package</var></file>, where
8981 <var>package</var> is the name of the package, and
8982 compressed with <tt>gzip -9</tt> unless it is small.
8986 If a package comes with large amounts of documentation which
8987 many users of the package will not require you should create
8988 a separate binary package to contain it, so that it does not
8989 take up disk space on the machines of users who do not need
8990 or want it installed.</p>
8993 It is often a good idea to put text information files
8994 (<file>README</file>s, changelogs, and so forth) that come with
8995 the source package in <file>/usr/share/doc/<var>package</var></file>
8996 in the binary package. However, you don't need to install
8997 the instructions for building and installing the package, of
9001 Packages must not require the existence of any files in
9002 <file>/usr/share/doc/</file> in order to function
9004 The system administrator should be able to
9005 delete files in <file>/usr/share/doc/</file> without causing
9006 any programs to break.
9008 Any files that are referenced by programs but are also
9009 useful as stand alone documentation should be installed under
9010 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9011 <file>/usr/share/doc/<var>package</var></file>.
9015 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9016 link to another directory in <file>/usr/share/doc</file> only if
9017 the two packages both come from the same source and the
9018 first package Depends on the second.<footnote>
9020 Please note that this does not override the section on
9021 changelog files below, so the file
9022 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
9023 must refer to the changelog for the current version of
9024 <var>package</var> in question. In practice, this means
9025 that the sources of the target and the destination of the
9026 symlink must be the same (same source package and
9033 Former Debian releases placed all additional documentation
9034 in <file>/usr/doc/<var>package</var></file>. This has been
9035 changed to <file>/usr/share/doc/<var>package</var></file>,
9036 and packages must not put documentation in the directory
9037 <file>/usr/doc/<var>package</var></file>. <footnote>
9038 At this phase of the transition, we no longer require a
9039 symbolic link in <file>/usr/doc/</file>. At a later point,
9040 policy shall change to make the symbolic links a bug.
9046 <heading>Preferred documentation formats</heading>
9049 The unification of Debian documentation is being carried out
9053 If your package comes with extensive documentation in a
9054 markup format that can be converted to various other formats
9055 you should if possible ship HTML versions in a binary
9056 package, in the directory
9057 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9058 its subdirectories.<footnote>
9059 The rationale: The important thing here is that HTML
9060 docs should be available in <em>some</em> package, not
9061 necessarily in the main binary package.
9066 Other formats such as PostScript may be provided at the
9067 package maintainer's discretion.
9071 <sect id="copyrightfile">
9072 <heading>Copyright information</heading>
9075 Every package must be accompanied by a verbatim copy of its
9076 copyright and distribution license in the file
9077 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9078 file must neither be compressed nor be a symbolic link.
9082 In addition, the copyright file must say where the upstream
9083 sources (if any) were obtained. It should name the original
9084 authors of the package and the Debian maintainer(s) who were
9085 involved with its creation.
9089 Packages in the <em>contrib</em> or <em>non-free</em> archive
9090 areas should state in the copyright file that the package is not
9091 part of the Debian GNU/Linux distribution and briefly explain
9096 A copy of the file which will be installed in
9097 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9098 be in <file>debian/copyright</file> in the source package.
9102 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9103 link to another directory in <file>/usr/share/doc</file> only if
9104 the two packages both come from the same source and the
9105 first package Depends on the second. These rules are
9106 important because copyrights must be extractable by
9111 Packages distributed under the UCB BSD license, the Apache
9112 license (version 2.0), the Artistic license, the GNU GPL
9113 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9114 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9115 files under <file>/usr/share/common-licenses</file>,<footnote>
9118 <file>/usr/share/common-licenses/BSD</file>,
9119 <file>/usr/share/common-licenses/Apache-2.0</file>,
9120 <file>/usr/share/common-licenses/Artistic</file>,
9121 <file>/usr/share/common-licenses/GPL-2</file>,
9122 <file>/usr/share/common-licenses/GPL-3</file>,
9123 <file>/usr/share/common-licenses/LGPL-2</file>,
9124 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9125 <file>/usr/share/common-licenses/LGPL-3</file>,
9126 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9127 <file>/usr/share/common-licenses/GFDL-1.3</file>
9130 </footnote> rather than quoting them in the copyright
9135 You should not use the copyright file as a general <file>README</file>
9136 file. If your package has such a file it should be
9137 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9138 <file>README.Debian</file> or some other appropriate place.</p>
9142 <heading>Examples</heading>
9145 Any examples (configurations, source files, whatever),
9146 should be installed in a directory
9147 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9148 files should not be referenced by any program: they're there
9149 for the benefit of the system administrator and users as
9150 documentation only. Architecture-specific example files
9151 should be installed in a directory
9152 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9154 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9155 latter directory itself may be a symbolic link to the
9160 If the purpose of a package is to provide examples, then the
9161 example files may be installed into
9162 <file>/usr/share/doc/<var>package</var></file>.
9166 <sect id="changelogs">
9167 <heading>Changelog files</heading>
9170 Packages that are not Debian-native must contain a
9171 compressed copy of the <file>debian/changelog</file> file from
9172 the Debian source tree in
9173 <file>/usr/share/doc/<var>package</var></file> with the name
9174 <file>changelog.Debian.gz</file>.
9178 If an upstream changelog is available, it should be accessible as
9179 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9180 plain text. If the upstream changelog is distributed in
9181 HTML, it should be made available in that form as
9182 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9183 and a plain text <file>changelog.gz</file> should be generated
9184 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9185 the upstream changelog files do not already conform to this
9186 naming convention, then this may be achieved either by
9187 renaming the files, or by adding a symbolic link, at the
9188 maintainer's discretion.<footnote>
9189 Rationale: People should not have to look in places for
9190 upstream changelogs merely because they are given
9191 different names or are distributed in HTML format.
9196 All of these files should be installed compressed using
9197 <tt>gzip -9</tt>, as they will become large with time even
9198 if they start out small.
9202 If the package has only one changelog which is used both as
9203 the Debian changelog and the upstream one because there is
9204 no separate upstream maintainer then that changelog should
9205 usually be installed as
9206 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9207 there is a separate upstream maintainer, but no upstream
9208 changelog, then the Debian changelog should still be called
9209 <file>changelog.Debian.gz</file>.
9213 For details about the format and contents of the Debian
9214 changelog file, please see <ref id="dpkgchangelog">.
9219 <appendix id="pkg-scope">
9220 <heading>Introduction and scope of these appendices</heading>
9223 These appendices are taken essentially verbatim from the
9224 now-deprecated Packaging Manual, version 3.2.1.0. They are
9225 the chapters which are likely to be of use to package
9226 maintainers and which have not already been included in the
9227 policy document itself. Most of these sections are very likely
9228 not relevant to policy; they should be treated as
9229 documentation for the packaging system. Please note that these
9230 appendices are included for convenience, and for historical
9231 reasons: they used to be part of policy package, and they have
9232 not yet been incorporated into dpkg documentation. However,
9233 they still have value, and hence they are presented here.
9237 They have not yet been checked to ensure that they are
9238 compatible with the contents of policy, and if there are any
9239 contradictions, the version in the main policy document takes
9240 precedence. The remaining chapters of the old Packaging
9241 Manual have also not been read in detail to ensure that there
9242 are not parts which have been left out. Both of these will be
9247 Certain parts of the Packaging manual were integrated into the
9248 Policy Manual proper, and removed from the appendices. Links
9249 have been placed from the old locations to the new ones.
9253 <prgn>dpkg</prgn> is a suite of programs for creating binary
9254 package files and installing and removing them on Unix
9256 <prgn>dpkg</prgn> is targeted primarily at Debian
9257 GNU/Linux, but may work on or be ported to other
9263 The binary packages are designed for the management of
9264 installed executable programs (usually compiled binaries) and
9265 their associated data, though source code examples and
9266 documentation are provided as part of some packages.</p>
9269 This manual describes the technical aspects of creating Debian
9270 binary packages (<file>.deb</file> files). It documents the
9271 behavior of the package management programs
9272 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9273 they interact with packages.</p>
9276 It also documents the interaction between
9277 <prgn>dselect</prgn>'s core and the access method scripts it
9278 uses to actually install the selected packages, and describes
9279 how to create a new access method.</p>
9282 This manual does not go into detail about the options and
9283 usage of the package building and installation tools. It
9284 should therefore be read in conjunction with those programs'
9289 The utility programs which are provided with <prgn>dpkg</prgn>
9290 for managing various system configuration and similar issues,
9291 such as <prgn>update-rc.d</prgn> and
9292 <prgn>install-info</prgn>, are not described in detail here -
9293 please see their man pages.
9297 It is assumed that the reader is reasonably familiar with the
9298 <prgn>dpkg</prgn> System Administrators' manual.
9299 Unfortunately this manual does not yet exist.
9303 The Debian version of the FSF's GNU hello program is provided
9304 as an example for people wishing to create Debian
9305 packages. The Debian <prgn>debmake</prgn> package is
9306 recommended as a very helpful tool in creating and maintaining
9307 Debian packages. However, while the tools and examples are
9308 helpful, they do not replace the need to read and follow the
9309 Policy and Programmer's Manual.</p>
9312 <appendix id="pkg-binarypkg">
9313 <heading>Binary packages (from old Packaging Manual)</heading>
9316 The binary package has two main sections. The first part
9317 consists of various control information files and scripts used
9318 by <prgn>dpkg</prgn> when installing and removing. See <ref
9319 id="pkg-controlarea">.
9323 The second part is an archive containing the files and
9324 directories to be installed.
9328 In the future binary packages may also contain other
9329 components, such as checksums and digital signatures. The
9330 format for the archive is described in full in the
9331 <file>deb(5)</file> man page.
9335 <sect id="pkg-bincreating"><heading>Creating package files -
9336 <prgn>dpkg-deb</prgn>
9340 All manipulation of binary package files is done by
9341 <prgn>dpkg-deb</prgn>; it's the only program that has
9342 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9343 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9344 will spot that the options requested are appropriate to
9345 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9350 In order to create a binary package you must make a
9351 directory tree which contains all the files and directories
9352 you want to have in the file system data part of the package.
9353 In Debian-format source packages this directory is usually
9354 <file>debian/tmp</file>, relative to the top of the package's
9359 They should have the locations (relative to the root of the
9360 directory tree you're constructing) ownerships and
9361 permissions which you want them to have on the system when
9366 With current versions of <prgn>dpkg</prgn> the uid/username
9367 and gid/groupname mappings for the users and groups being
9368 used should be the same on the system where the package is
9369 built and the one where it is installed.
9373 You need to add one special directory to the root of the
9374 miniature file system tree you're creating:
9375 <prgn>DEBIAN</prgn>. It should contain the control
9376 information files, notably the binary package control file
9377 (see <ref id="pkg-controlfile">).
9381 The <prgn>DEBIAN</prgn> directory will not appear in the
9382 file system archive of the package, and so won't be installed
9383 by <prgn>dpkg</prgn> when the package is installed.
9387 When you've prepared the package, you should invoke:
9389 dpkg --build <var>directory</var>
9394 This will build the package in
9395 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9396 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9397 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9402 See the man page <manref name="dpkg-deb" section="8"> for details of how
9403 to examine the contents of this newly-created file. You may find the
9404 output of following commands enlightening:
9406 dpkg-deb --info <var>filename</var>.deb
9407 dpkg-deb --contents <var>filename</var>.deb
9408 dpkg --contents <var>filename</var>.deb
9410 To view the copyright file for a package you could use this command:
9412 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9417 <sect id="pkg-controlarea">
9418 <heading>Package control information files</heading>
9421 The control information portion of a binary package is a
9422 collection of files with names known to <prgn>dpkg</prgn>.
9423 It will treat the contents of these files specially - some
9424 of them contain information used by <prgn>dpkg</prgn> when
9425 installing or removing the package; others are scripts which
9426 the package maintainer wants <prgn>dpkg</prgn> to run.
9430 It is possible to put other files in the package control
9431 area, but this is not generally a good idea (though they
9432 will largely be ignored).
9436 Here is a brief list of the control info files supported by
9437 <prgn>dpkg</prgn> and a summary of what they're used for.
9442 <tag><tt>control</tt>
9445 This is the key description file used by
9446 <prgn>dpkg</prgn>. It specifies the package's name
9447 and version, gives its description for the user,
9448 states its relationships with other packages, and so
9449 forth. See <ref id="sourcecontrolfiles"> and
9450 <ref id="binarycontrolfiles">.
9454 It is usually generated automatically from information
9455 in the source package by the
9456 <prgn>dpkg-gencontrol</prgn> program, and with
9457 assistance from <prgn>dpkg-shlibdeps</prgn>.
9458 See <ref id="pkg-sourcetools">.
9462 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9467 These are executable files (usually scripts) which
9468 <prgn>dpkg</prgn> runs during installation, upgrade
9469 and removal of packages. They allow the package to
9470 deal with matters which are particular to that package
9471 or require more complicated processing than that
9472 provided by <prgn>dpkg</prgn>. Details of when and
9473 how they are called are in <ref id="maintainerscripts">.
9477 It is very important to make these scripts idempotent.
9478 See <ref id="idempotency">.
9482 The maintainer scripts are guaranteed to run with a
9483 controlling terminal and can interact with the user.
9484 See <ref id="controllingterminal">.
9488 <tag><tt>conffiles</tt>
9491 This file contains a list of configuration files which
9492 are to be handled automatically by <prgn>dpkg</prgn>
9493 (see <ref id="pkg-conffiles">). Note that not necessarily
9494 every configuration file should be listed here.
9497 <tag><tt>shlibs</tt>
9500 This file contains a list of the shared libraries
9501 supplied by the package, with dependency details for
9502 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9503 when it determines what dependencies are required in a
9504 package control file. The <tt>shlibs</tt> file format
9505 is described on <ref id="shlibs">.
9510 <sect id="pkg-controlfile">
9511 <heading>The main control information file: <tt>control</tt></heading>
9514 The most important control information file used by
9515 <prgn>dpkg</prgn> when it installs a package is
9516 <tt>control</tt>. It contains all the package's "vital
9521 The binary package control files of packages built from
9522 Debian sources are made by a special tool,
9523 <prgn>dpkg-gencontrol</prgn>, which reads
9524 <file>debian/control</file> and <file>debian/changelog</file> to
9525 find the information it needs. See <ref id="pkg-sourcepkg"> for
9530 The fields in binary package control files are listed in
9531 <ref id="binarycontrolfiles">.
9535 A description of the syntax of control files and the purpose
9536 of the fields is available in <ref id="controlfields">.
9541 <heading>Time Stamps</heading>
9544 See <ref id="timestamps">.
9549 <appendix id="pkg-sourcepkg">
9550 <heading>Source packages (from old Packaging Manual) </heading>
9553 The Debian binary packages in the distribution are generated
9554 from Debian sources, which are in a special format to assist
9555 the easy and automatic building of binaries.
9558 <sect id="pkg-sourcetools">
9559 <heading>Tools for processing source packages</heading>
9562 Various tools are provided for manipulating source packages;
9563 they pack and unpack sources and help build of binary
9564 packages and help manage the distribution of new versions.
9568 They are introduced and typical uses described here; see
9569 <manref name="dpkg-source" section="1"> for full
9570 documentation about their arguments and operation.
9574 For examples of how to construct a Debian source package,
9575 and how to use those utilities that are used by Debian
9576 source packages, please see the <prgn>hello</prgn> example
9580 <sect1 id="pkg-dpkg-source">
9582 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9587 This program is frequently used by hand, and is also
9588 called from package-independent automated building scripts
9589 such as <prgn>dpkg-buildpackage</prgn>.
9593 To unpack a package it is typically invoked with
9595 dpkg-source -x <var>.../path/to/filename</var>.dsc
9600 with the <file><var>filename</var>.tar.gz</file> and
9601 <file><var>filename</var>.diff.gz</file> (if applicable) in
9602 the same directory. It unpacks into
9603 <file><var>package</var>-<var>version</var></file>, and if
9605 <file><var>package</var>-<var>version</var>.orig</file>, in
9606 the current directory.
9610 To create a packed source archive it is typically invoked:
9612 dpkg-source -b <var>package</var>-<var>version</var>
9617 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9618 <file>.diff.gz</file> (if appropriate) in the current
9619 directory. <prgn>dpkg-source</prgn> does not clean the
9620 source tree first - this must be done separately if it is
9625 See also <ref id="pkg-sourcearchives">.</p>
9629 <sect1 id="pkg-dpkg-buildpackage">
9631 <prgn>dpkg-buildpackage</prgn> - overall package-building
9636 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9637 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9638 targets <tt>clean</tt>, <tt>build</tt> and
9639 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9640 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9641 source and binary package upload.
9645 It is usually invoked by hand from the top level of the
9646 built or unbuilt source directory. It may be invoked with
9647 no arguments; useful arguments include:
9648 <taglist compact="compact">
9649 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9652 Do not sign the <tt>.changes</tt> file or the
9653 source package <tt>.dsc</tt> file, respectively.</p>
9655 <tag><tt>-p<var>sign-command</var></tt></tag>
9658 Invoke <var>sign-command</var> instead of finding
9659 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9660 <var>sign-command</var> must behave just like
9661 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9663 <tag><tt>-r<var>root-command</var></tt></tag>
9666 When root privilege is required, invoke the command
9667 <var>root-command</var>. <var>root-command</var>
9668 should invoke its first argument as a command, from
9669 the <prgn>PATH</prgn> if necessary, and pass its
9670 second and subsequent arguments to the command it
9671 calls. If no <var>root-command</var> is supplied
9672 then <var>dpkg-buildpackage</var> will take no
9673 special action to gain root privilege, so that for
9674 most packages it will have to be invoked as root to
9677 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9680 Two types of binary-only build and upload - see
9681 <manref name="dpkg-source" section="1">.
9688 <sect1 id="pkg-dpkg-gencontrol">
9690 <prgn>dpkg-gencontrol</prgn> - generates binary package
9695 This program is usually called from <file>debian/rules</file>
9696 (see <ref id="pkg-sourcetree">) in the top level of the source
9701 This is usually done just before the files and directories in the
9702 temporary directory tree where the package is being built have their
9703 permissions and ownerships set and the package is constructed using
9704 <prgn>dpkg-deb/</prgn>
9706 This is so that the control file which is produced has
9707 the right permissions
9712 <prgn>dpkg-gencontrol</prgn> must be called after all the
9713 files which are to go into the package have been placed in
9714 the temporary build directory, so that its calculation of
9715 the installed size of a package is correct.
9719 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9720 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9721 variable substitutions created by
9722 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9727 For a package which generates only one binary package, and
9728 which builds it in <file>debian/tmp</file> relative to the top
9729 of the source package, it is usually sufficient to call
9730 <prgn>dpkg-gencontrol</prgn>.
9734 Sources which build several binaries will typically need
9737 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9738 </example> The <tt>-P</tt> tells
9739 <prgn>dpkg-gencontrol</prgn> that the package is being
9740 built in a non-default directory, and the <tt>-p</tt>
9741 tells it which package's control file should be generated.
9745 <prgn>dpkg-gencontrol</prgn> also adds information to the
9746 list of files in <file>debian/files</file>, for the benefit of
9747 (for example) a future invocation of
9748 <prgn>dpkg-genchanges</prgn>.</p>
9751 <sect1 id="pkg-dpkg-shlibdeps">
9753 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9758 This program is usually called from <file>debian/rules</file>
9759 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9760 id="pkg-sourcetree">), in the top level of the source tree.
9764 Its arguments are executables and shared libraries
9767 They may be specified either in the locations in the
9768 source tree where they are created or in the locations
9769 in the temporary build tree where they are installed
9770 prior to binary package creation.
9772 </footnote> for which shared library dependencies should
9773 be included in the binary package's control file.
9777 If some of the found shared libraries should only
9778 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9779 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9780 by using the <tt>-d<var>dependency-field</var></tt> option
9781 before those executable(s). (Each <tt>-d</tt> option
9782 takes effect until the next <tt>-d</tt>.)
9786 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9787 output control file to be modified. Instead by default it
9788 adds to the <file>debian/substvars</file> file variable
9789 settings like <tt>shlibs:Depends</tt>. These variable
9790 settings must be referenced in dependency fields in the
9791 appropriate per-binary-package sections of the source
9796 For example, a package that generates an essential part
9797 which requires dependencies, and optional parts that
9798 which only require a recommendation, would separate those
9799 two sets of dependencies into two different fields.<footnote>
9800 At the time of writing, an example for this was the
9801 <package/xmms/ package, with Depends used for the xmms
9802 executable, Recommends for the plug-ins and Suggests for
9803 even more optional features provided by unzip.
9805 It can say in its <file>debian/rules</file>:
9807 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9808 -dRecommends <var>optionalpart anotheroptionalpart</var>
9810 and then in its main control file <file>debian/control</file>:
9813 Depends: ${shlibs:Depends}
9814 Recommends: ${shlibs:Recommends}
9820 Sources which produce several binary packages with
9821 different shared library dependency requirements can use
9822 the <tt>-p<var>varnameprefix</var></tt> option to override
9823 the default <tt>shlibs:</tt> prefix (one invocation of
9824 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9825 They can thus produce several sets of dependency
9826 variables, each of the form
9827 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9828 which can be referred to in the appropriate parts of the
9829 binary package control files.
9834 <sect1 id="pkg-dpkg-distaddfile">
9836 <prgn>dpkg-distaddfile</prgn> - adds a file to
9837 <file>debian/files</file>
9841 Some packages' uploads need to include files other than
9842 the source and binary package files.
9846 <prgn>dpkg-distaddfile</prgn> adds a file to the
9847 <file>debian/files</file> file so that it will be included in
9848 the <file>.changes</file> file when
9849 <prgn>dpkg-genchanges</prgn> is run.
9853 It is usually invoked from the <tt>binary</tt> target of
9854 <file>debian/rules</file>:
9856 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9858 The <var>filename</var> is relative to the directory where
9859 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9860 is usually the directory above the top level of the source
9861 tree. The <file>debian/rules</file> target should put the
9862 file there just before or just after calling
9863 <prgn>dpkg-distaddfile</prgn>.
9867 The <var>section</var> and <var>priority</var> are passed
9868 unchanged into the resulting <file>.changes</file> file.
9873 <sect1 id="pkg-dpkg-genchanges">
9875 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9880 This program is usually called by package-independent
9881 automatic building scripts such as
9882 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9887 It is usually called in the top level of a built source
9888 tree, and when invoked with no arguments will print out a
9889 straightforward <file>.changes</file> file based on the
9890 information in the source package's changelog and control
9891 file and the binary and source packages which should have
9897 <sect1 id="pkg-dpkg-parsechangelog">
9899 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9900 representation of a changelog
9904 This program is used internally by
9905 <prgn>dpkg-source</prgn> et al. It may also occasionally
9906 be useful in <file>debian/rules</file> and elsewhere. It
9907 parses a changelog, <file>debian/changelog</file> by default,
9908 and prints a control-file format representation of the
9909 information in it to standard output.
9913 <sect1 id="pkg-dpkg-architecture">
9915 <prgn>dpkg-architecture</prgn> - information about the build and
9920 This program can be used manually, but is also invoked by
9921 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9922 environment or make variables which specify the build and host
9923 architecture for the package building process.
9928 <sect id="pkg-sourcetree">
9929 <heading>The Debianised source tree</heading>
9932 The source archive scheme described later is intended to
9933 allow a Debianised source tree with some associated control
9934 information to be reproduced and transported easily. The
9935 Debianised source tree is a version of the original program
9936 with certain files added for the benefit of the
9937 Debianisation process, and with any other changes required
9938 made to the rest of the source code and installation
9943 The extra files created for Debian are in the subdirectory
9944 <file>debian</file> of the top level of the Debianised source
9945 tree. They are described below.
9948 <sect1 id="pkg-debianrules">
9949 <heading><file>debian/rules</file> - the main building script</heading>
9952 See <ref id="debianrules">.
9957 <sect1 id="pkg-dpkgchangelog">
9958 <heading><file>debian/changelog</file></heading>
9961 See <ref id="dpkgchangelog">.
9964 <sect2><heading>Defining alternative changelog formats
9968 It is possible to use a different format to the standard
9969 one, by providing a parser for the format you wish to
9974 In order to have <tt>dpkg-parsechangelog</tt> run your
9975 parser, you must include a line within the last 40 lines
9976 of your file matching the Perl regular expression:
9977 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9978 parentheses should be the name of the format. For
9979 example, you might say:
9981 @@@ changelog-format: joebloggs @@@
9983 Changelog format names are non-empty strings of alphanumerics.
9987 If such a line exists then <tt>dpkg-parsechangelog</tt>
9988 will look for the parser as
9989 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9991 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9992 it is an error for it not to find it, or for it not to
9993 be an executable program. The default changelog format
9994 is <tt>dpkg</tt>, and a parser for it is provided with
9995 the <tt>dpkg</tt> package.
9999 The parser will be invoked with the changelog open on
10000 standard input at the start of the file. It should read
10001 the file (it may seek if it wishes) to determine the
10002 information required and return the parsed information
10003 to standard output in the form of a series of control
10004 fields in the standard format. By default it should
10005 return information about only the most recent version in
10006 the changelog; it should accept a
10007 <tt>-v<var>version</var></tt> option to return changes
10008 information from all versions present <em>strictly
10009 after</em> <var>version</var>, and it should then be an
10010 error for <var>version</var> not to be present in the
10016 <list compact="compact">
10017 <item><qref id="f-Source"><tt>Source</tt></qref></item>
10018 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
10019 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
10020 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
10021 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
10022 <item><qref id="f-Date"><tt>Date</tt></qref></item>
10023 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
10028 If several versions are being returned (due to the use
10029 of <tt>-v</tt>), the urgency value should be of the
10030 highest urgency code listed at the start of any of the
10031 versions requested followed by the concatenated
10032 (space-separated) comments from all the versions
10033 requested; the maintainer, version, distribution and
10034 date should always be from the most recent version.
10038 For the format of the <tt>Changes</tt> field see
10039 <ref id="f-Changes">.
10043 If the changelog format which is being parsed always or
10044 almost always leaves a blank line between individual
10045 change notes these blank lines should be stripped out,
10046 so as to make the resulting output compact.
10050 If the changelog format does not contain date or package
10051 name information this information should be omitted from
10052 the output. The parser should not attempt to synthesize
10053 it or find it from other sources.
10057 If the changelog does not have the expected format the
10058 parser should exit with a nonzero exit status, rather
10059 than trying to muddle through and possibly generating
10064 A changelog parser may not interact with the user at
10070 <sect1 id="pkg-srcsubstvars">
10071 <heading><file>debian/substvars</file> and variable substitutions</heading>
10074 See <ref id="substvars">.
10080 <heading><file>debian/files</file></heading>
10083 See <ref id="debianfiles">.
10087 <sect1><heading><file>debian/tmp</file>
10091 This is the canonical temporary location for the
10092 construction of binary packages by the <tt>binary</tt>
10093 target. The directory <file>tmp</file> serves as the root of
10094 the file system tree as it is being constructed (for
10095 example, by using the package's upstream makefiles install
10096 targets and redirecting the output there), and it also
10097 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10098 id="pkg-bincreating">.
10102 If several binary packages are generated from the same
10103 source tree it is usual to use several
10104 <file>debian/tmp<var>something</var></file> directories, for
10105 example <file>tmp-a</file> or <file>tmp-doc</file>.
10109 Whatever <file>tmp</file> directories are created and used by
10110 <tt>binary</tt> must of course be removed by the
10111 <tt>clean</tt> target.</p></sect1>
10115 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10119 As it exists on the FTP site, a Debian source package
10120 consists of three related files. You must have the right
10121 versions of all three to be able to use them.
10126 <tag>Debian source control file - <tt>.dsc</tt></tag>
10128 This file is a control file used by <prgn>dpkg-source</prgn>
10129 to extract a source package.
10130 See <ref id="debiansourcecontrolfiles">.
10134 Original source archive -
10136 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10142 This is a compressed (with <tt>gzip -9</tt>)
10143 <prgn>tar</prgn> file containing the source code from
10144 the upstream authors of the program.
10149 Debianisation diff -
10151 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10157 This is a unified context diff (<tt>diff -u</tt>)
10158 giving the changes which are required to turn the
10159 original source into the Debian source. These changes
10160 may only include editing and creating plain files.
10161 The permissions of files, the targets of symbolic
10162 links and the characteristics of special files or
10163 pipes may not be changed and no files may be removed
10168 All the directories in the diff must exist, except the
10169 <file>debian</file> subdirectory of the top of the source
10170 tree, which will be created by
10171 <prgn>dpkg-source</prgn> if necessary when unpacking.
10175 The <prgn>dpkg-source</prgn> program will
10176 automatically make the <file>debian/rules</file> file
10177 executable (see below).</p></item>
10182 If there is no original source code - for example, if the
10183 package is specially prepared for Debian or the Debian
10184 maintainer is the same as the upstream maintainer - the
10185 format is slightly different: then there is no diff, and the
10187 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10188 and preferably contains a directory named
10189 <file><var>package</var>-<var>version</var></file>.
10194 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10197 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10198 Debian source package. However, if it is not available it
10199 is possible to unpack a Debian source archive as follows:
10200 <enumlist compact="compact">
10203 Untar the tarfile, which will create a <file>.orig</file>
10207 <p>Rename the <file>.orig</file> directory to
10208 <file><var>package</var>-<var>version</var></file>.</p>
10212 Create the subdirectory <file>debian</file> at the top of
10213 the source tree.</p>
10215 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10217 <item><p>Untar the tarfile again if you want a copy of the original
10218 source code alongside the Debianised version.</p>
10223 It is not possible to generate a valid Debian source archive
10224 without using <prgn>dpkg-source</prgn>. In particular,
10225 attempting to use <prgn>diff</prgn> directly to generate the
10226 <file>.diff.gz</file> file will not work.
10230 <heading>Restrictions on objects in source packages</heading>
10233 The source package may not contain any hard links
10235 This is not currently detected when building source
10236 packages, but only when extracting
10240 Hard links may be permitted at some point in the
10241 future, but would require a fair amount of
10243 </footnote>, device special files, sockets or setuid or
10246 Setgid directories are allowed.
10251 The source packaging tools manage the changes between the
10252 original and Debianised source using <prgn>diff</prgn> and
10253 <prgn>patch</prgn>. Turning the original source tree as
10254 included in the <file>.orig.tar.gz</file> into the debianised
10255 source must not involve any changes which cannot be
10256 handled by these tools. Problematic changes which cause
10257 <prgn>dpkg-source</prgn> to halt with an error when
10258 building the source package are:
10259 <list compact="compact">
10260 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10262 <item><p>Changing the targets of symbolic links.</p>
10264 <item><p>Creating directories, other than <file>debian</file>.</p>
10266 <item><p>Changes to the contents of binary files.</p></item>
10267 </list> Changes which cause <prgn>dpkg-source</prgn> to
10268 print a warning but continue anyway are:
10269 <list compact="compact">
10272 Removing files, directories or symlinks.
10274 Renaming a file is not treated specially - it is
10275 seen as the removal of the old file (which
10276 generates a warning, but is otherwise ignored),
10277 and the creation of the new one.
10283 Changed text files which are missing the usual final
10284 newline (either in the original or the modified
10289 Changes which are not represented, but which are not detected by
10290 <prgn>dpkg-source</prgn>, are:
10291 <list compact="compact">
10292 <item><p>Changing the permissions of files (other than
10293 <file>debian/rules</file>) and directories.</p></item>
10298 The <file>debian</file> directory and <file>debian/rules</file>
10299 are handled specially by <prgn>dpkg-source</prgn> - before
10300 applying the changes it will create the <file>debian</file>
10301 directory, and afterwards it will make
10302 <file>debian/rules</file> world-executable.
10308 <appendix id="pkg-controlfields">
10309 <heading>Control files and their fields (from old Packaging Manual)</heading>
10312 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10313 data in a common format, known as control files. Binary and
10314 source packages have control data as do the <file>.changes</file>
10315 files which control the installation of uploaded files, and
10316 <prgn>dpkg</prgn>'s internal databases are in a similar
10321 <heading>Syntax of control files</heading>
10324 See <ref id="controlsyntax">.
10328 It is important to note that there are several fields which
10329 are optional as far as <prgn>dpkg</prgn> and the related
10330 tools are concerned, but which must appear in every Debian
10331 package, or whose omission may cause problems.
10336 <heading>List of fields</heading>
10339 See <ref id="controlfieldslist">.
10343 This section now contains only the fields that didn't belong
10344 to the Policy manual.
10347 <sect1 id="pkg-f-Filename">
10348 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10351 These fields in <tt>Packages</tt> files give the
10352 filename(s) of (the parts of) a package in the
10353 distribution directories, relative to the root of the
10354 Debian hierarchy. If the package has been split into
10355 several parts the parts are all listed in order, separated
10360 <sect1 id="pkg-f-Size">
10361 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10364 These fields in <file>Packages</file> files give the size (in
10365 bytes, expressed in decimal) and MD5 checksum of the
10366 file(s) which make(s) up a binary package in the
10367 distribution. If the package is split into several parts
10368 the values for the parts are listed in order, separated by
10373 <sect1 id="pkg-f-Status">
10374 <heading><tt>Status</tt></heading>
10377 This field in <prgn>dpkg</prgn>'s status file records
10378 whether the user wants a package installed, removed or
10379 left alone, whether it is broken (requiring
10380 re-installation) or not and what its current state on the
10381 system is. Each of these pieces of information is a
10386 <sect1 id="pkg-f-Config-Version">
10387 <heading><tt>Config-Version</tt></heading>
10390 If a package is not installed or not configured, this
10391 field in <prgn>dpkg</prgn>'s status file records the last
10392 version of the package which was successfully
10397 <sect1 id="pkg-f-Conffiles">
10398 <heading><tt>Conffiles</tt></heading>
10401 This field in <prgn>dpkg</prgn>'s status file contains
10402 information about the automatically-managed configuration
10403 files held by a package. This field should <em>not</em>
10404 appear anywhere in a package!
10409 <heading>Obsolete fields</heading>
10412 These are still recognized by <prgn>dpkg</prgn> but should
10413 not appear anywhere any more.
10415 <taglist compact="compact">
10417 <tag><tt>Revision</tt></tag>
10418 <tag><tt>Package-Revision</tt></tag>
10419 <tag><tt>Package_Revision</tt></tag>
10421 The Debian revision part of the package version was
10422 at one point in a separate control file field. This
10423 field went through several names.
10426 <tag><tt>Recommended</tt></tag>
10427 <item>Old name for <tt>Recommends</tt>.</item>
10429 <tag><tt>Optional</tt></tag>
10430 <item>Old name for <tt>Suggests</tt>.</item>
10432 <tag><tt>Class</tt></tag>
10433 <item>Old name for <tt>Priority</tt>.</item>
10442 <appendix id="pkg-conffiles">
10443 <heading>Configuration file handling (from old Packaging Manual)</heading>
10446 <prgn>dpkg</prgn> can do a certain amount of automatic
10447 handling of package configuration files.
10451 Whether this mechanism is appropriate depends on a number of
10452 factors, but basically there are two approaches to any
10453 particular configuration file.
10457 The easy method is to ship a best-effort configuration in the
10458 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10459 handle updates. If the user is unlikely to want to edit the
10460 file, but you need them to be able to without losing their
10461 changes, and a new package with a changed version of the file
10462 is only released infrequently, this is a good approach.
10466 The hard method is to build the configuration file from
10467 scratch in the <prgn>postinst</prgn> script, and to take the
10468 responsibility for fixing any mistakes made in earlier
10469 versions of the package automatically. This will be
10470 appropriate if the file is likely to need to be different on
10474 <sect><heading>Automatic handling of configuration files by
10479 A package may contain a control area file called
10480 <tt>conffiles</tt>. This file should be a list of filenames
10481 of configuration files needing automatic handling, separated
10482 by newlines. The filenames should be absolute pathnames,
10483 and the files referred to should actually exist in the
10488 When a package is upgraded <prgn>dpkg</prgn> will process
10489 the configuration files during the configuration stage,
10490 shortly before it runs the package's <prgn>postinst</prgn>
10495 For each file it checks to see whether the version of the
10496 file included in the package is the same as the one that was
10497 included in the last version of the package (the one that is
10498 being upgraded from); it also compares the version currently
10499 installed on the system with the one shipped with the last
10504 If neither the user nor the package maintainer has changed
10505 the file, it is left alone. If one or the other has changed
10506 their version, then the changed version is preferred - i.e.,
10507 if the user edits their file, but the package maintainer
10508 doesn't ship a different version, the user's changes will
10509 stay, silently, but if the maintainer ships a new version
10510 and the user hasn't edited it the new version will be
10511 installed (with an informative message). If both have
10512 changed their version the user is prompted about the problem
10513 and must resolve the differences themselves.
10517 The comparisons are done by calculating the MD5 message
10518 digests of the files, and storing the MD5 of the file as it
10519 was included in the most recent version of the package.
10523 When a package is installed for the first time
10524 <prgn>dpkg</prgn> will install the file that comes with it,
10525 unless that would mean overwriting a file already on the
10530 However, note that <prgn>dpkg</prgn> will <em>not</em>
10531 replace a conffile that was removed by the user (or by a
10532 script). This is necessary because with some programs a
10533 missing file produces an effect hard or impossible to
10534 achieve in another way, so that a missing file needs to be
10535 kept that way if the user did it.
10539 Note that a package should <em>not</em> modify a
10540 <prgn>dpkg</prgn>-handled conffile in its maintainer
10541 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10542 the user confusing and possibly dangerous options for
10543 conffile update when the package is upgraded.</p>
10546 <sect><heading>Fully-featured maintainer script configuration
10551 For files which contain site-specific information such as
10552 the hostname and networking details and so forth, it is
10553 better to create the file in the package's
10554 <prgn>postinst</prgn> script.
10558 This will typically involve examining the state of the rest
10559 of the system to determine values and other information, and
10560 may involve prompting the user for some information which
10561 can't be obtained some other way.
10565 When using this method there are a couple of important
10566 issues which should be considered:
10570 If you discover a bug in the program which generates the
10571 configuration file, or if the format of the file changes
10572 from one version to the next, you will have to arrange for
10573 the postinst script to do something sensible - usually this
10574 will mean editing the installed configuration file to remove
10575 the problem or change the syntax. You will have to do this
10576 very carefully, since the user may have changed the file,
10577 perhaps to fix the very problem that your script is trying
10578 to deal with - you will have to detect these situations and
10579 deal with them correctly.
10583 If you do go down this route it's probably a good idea to
10584 make the program that generates the configuration file(s) a
10585 separate program in <file>/usr/sbin</file>, by convention called
10586 <file><var>package</var>config</file> and then run that if
10587 appropriate from the post-installation script. The
10588 <tt><var>package</var>config</tt> program should not
10589 unquestioningly overwrite an existing configuration - if its
10590 mode of operation is geared towards setting up a package for
10591 the first time (rather than any arbitrary reconfiguration
10592 later) you should have it check whether the configuration
10593 already exists, and require a <tt>--force</tt> flag to
10594 overwrite it.</p></sect>
10597 <appendix id="pkg-alternatives"><heading>Alternative versions of
10598 an interface - <prgn>update-alternatives</prgn> (from old
10603 When several packages all provide different versions of the
10604 same program or file it is useful to have the system select a
10605 default, but to allow the system administrator to change it
10606 and have their decisions respected.
10610 For example, there are several versions of the <prgn>vi</prgn>
10611 editor, and there is no reason to prevent all of them from
10612 being installed at once, each under their own name
10613 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10614 Nevertheless it is desirable to have the name <tt>vi</tt>
10615 refer to something, at least by default.
10619 If all the packages involved cooperate, this can be done with
10620 <prgn>update-alternatives</prgn>.
10624 Each package provides its own version under its own name, and
10625 calls <prgn>update-alternatives</prgn> in its postinst to
10626 register its version (and again in its prerm to deregister
10631 See the man page <manref name="update-alternatives"
10632 section="8"> for details.
10636 If <prgn>update-alternatives</prgn> does not seem appropriate
10637 you may wish to consider using diversions instead.</p>
10640 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10641 package's version of a file (from old Packaging Manual)
10645 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10646 when it reinstalls the package it belongs to, and to have it
10647 put the file from the package somewhere else instead.
10651 This can be used locally to override a package's version of a
10652 file, or by one package to override another's version (or
10653 provide a wrapper for it).
10657 Before deciding to use a diversion, read <ref
10658 id="pkg-alternatives"> to see if you really want a diversion
10659 rather than several alternative versions of a program.
10663 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10664 and updated by a special program <prgn>dpkg-divert</prgn>.
10665 Please see <manref name="dpkg-divert" section="8"> for full
10666 details of its operation.
10670 When a package wishes to divert a file from another, it should
10671 call <prgn>dpkg-divert</prgn> in its preinst to add the
10672 diversion and rename the existing file. For example,
10673 supposing that a <prgn>smailwrapper</prgn> package wishes to
10674 install a wrapper around <file>/usr/sbin/smail</file>:
10676 dpkg-divert --package smailwrapper --add --rename \
10677 --divert /usr/sbin/smail.real /usr/sbin/smail
10678 </example> The <tt>--package smailwrapper</tt> ensures that
10679 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10680 can bypass the diversion and get installed as the true version.
10681 It's safe to add the diversion unconditionally on upgrades since
10682 it will be left unchanged if it already exists, but
10683 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10684 message, make the command conditional on the version from which
10685 the package is being upgraded:
10687 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10688 dpkg-divert --package smailwrapper --add --rename \
10689 --divert /usr/sbin/smail.real /usr/sbin/smail
10691 </example> where <tt>1.0-2</tt> is the version at which the
10692 diversion was first added to the package. Running the command
10693 during abort-upgrade is pointless but harmless.
10697 The postrm has to do the reverse:
10699 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10700 dpkg-divert --package smailwrapper --remove --rename \
10701 --divert /usr/sbin/smail.real /usr/sbin/smail
10703 </example> If the diversion was added at a particular version, the
10704 postrm should also handle the failure case of upgrading from an
10705 older version (unless the older version is so old that direct
10706 upgrades are no longer supported):
10708 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10709 dpkg-divert --package smailwrapper --remove --rename \
10710 --divert /usr/sbin/smail.real /usr/sbin/smail
10712 </example> where <tt>1.02-2</tt> is the version at which the
10713 diversion was first added to the package. The postrm should not
10714 remove the diversion on upgrades both because there's no reason to
10715 remove the diversion only to immediately re-add it and since the
10716 postrm of the old package is run after unpacking so the removal of
10717 the diversion will fail.
10721 Do not attempt to divert a file which is vitally important for
10722 the system's operation - when using <prgn>dpkg-divert</prgn>
10723 there is a time, after it has been diverted but before
10724 <prgn>dpkg</prgn> has installed the new version, when the file
10725 does not exist.</p>
10730 <!-- Local variables: -->
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