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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">.
2734 An architecture wildcard identifying a set of Debian
2735 machine architectures, see <ref id="arch-wildcard-spec">.
2737 <item><tt>all</tt>, which indicates an
2738 architecture-independent package.
2739 <item><tt>any</tt>, which indicates a package available
2740 for building on any architecture.
2741 <item><tt>source</tt>, which indicates a source package.
2746 In the main <file>debian/control</file> file in the source
2747 package, this field may contain the special value
2748 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2749 specific and wildcard architectures separated by
2750 spaces. If the special value <tt>any</tt> appears, it must
2751 be the entire contents of the field. Most packages will
2752 use either <tt>any</tt> or <tt>all</tt>. Specifying a
2753 specific list of architectures is for the minority of
2754 cases where a program is not portable or is not useful on
2755 some architectures, and where possible the program should
2756 be made portable instead.
2760 In the source package control file <file>.dsc</file>, this
2761 field may contain either the special value <tt>any</tt> or a
2762 list of architectures separated by spaces. If a list is given,
2763 it may include (or consist solely of) the special value
2764 <tt>all</tt>. In other words, in <file>.dsc</file> files
2765 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2766 in combination with specific architectures. The
2767 <tt>Architecture</tt> field in the source package control file
2768 <file>.dsc</file> is generally constructed from the
2769 <tt>Architecture</tt> fields in the
2770 <file>debian/control</file> in the source package.
2774 Specifying <tt>any</tt> indicates that the source package
2775 isn't dependent on any particular architecture and should
2776 compile fine on any one. The produced binary package(s)
2777 will either be specific to whatever the current build
2778 architecture is or will be architecture-independent.
2782 Specifying only <tt>all</tt> indicates that the source package
2783 will only build architecture-independent packages. If this is
2784 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2785 <tt>any</tt> implies that the source package will build at
2786 least one architecture-dependent package.
2790 Specifying a list of architectures indicates that the source
2791 will build an architecture-dependent package, and will only
2792 work correctly on the listed architectures. If the source
2793 package also builds at least one architecture-independent
2794 package, <tt>all</tt> will also be included in the list.
2798 Specifying a list of architecture wildcards indicates that
2799 the source will build an architecture-dependent package on
2800 the union of the lists of architectures from the expansion
2801 of each specified architecture wildcard, and will only
2802 work correctly on the architectures in the union of the
2803 lists.<footnote> As mentioned in the footnote for
2804 specifying a list of architectures, this is for a minority
2805 of cases where the program is not portable. Generally, it
2806 should not be used for new packages. Wildcards are not
2807 expanded into a list of known architectures before
2808 comparing to the build architecutre. Instead, the build
2809 architecture is matched against wildcards and this package
2810 is built if the wildcard matches.</footnote> If the source
2811 package also builds at least one architecture-independent
2812 package, <tt>all</tt> will also be included in the list.
2816 In a <file>.changes</file> file, the <tt>Architecture</tt>
2817 field lists the architecture(s) of the package(s)
2818 currently being uploaded. This will be a list; if the
2819 source for the package is also being uploaded, the special
2820 entry <tt>source</tt> is also present. <tt>all</tt> will be
2821 present if any architecture-independent packages are being
2822 uploaded. <tt>any</tt> may never occur in the
2823 <tt>Architecture</tt> field in the <file>.changes</file>
2828 See <ref id="debianrules"> for information on how to get
2829 the architecture for the build process.
2833 <sect1 id="f-Essential">
2834 <heading><tt>Essential</tt></heading>
2837 This is a boolean field which may occur only in the
2838 control file of a binary package or in a per-package fields
2839 paragraph of a main source control data file.
2843 If set to <tt>yes</tt> then the package management system
2844 will refuse to remove the package (upgrading and replacing
2845 it is still possible). The other possible value is <tt>no</tt>,
2846 which is the same as not having the field at all.
2851 <heading>Package interrelationship fields:
2852 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2853 <tt>Recommends</tt>, <tt>Suggests</tt>,
2854 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2855 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2859 These fields describe the package's relationships with
2860 other packages. Their syntax and semantics are described
2861 in <ref id="relationships">.</p>
2864 <sect1 id="f-Standards-Version">
2865 <heading><tt>Standards-Version</tt></heading>
2868 The most recent version of the standards (the policy
2869 manual and associated texts) with which the package
2874 The version number has four components: major and minor
2875 version number and major and minor patch level. When the
2876 standards change in a way that requires every package to
2877 change the major number will be changed. Significant
2878 changes that will require work in many packages will be
2879 signaled by a change to the minor number. The major patch
2880 level will be changed for any change to the meaning of the
2881 standards, however small; the minor patch level will be
2882 changed when only cosmetic, typographical or other edits
2883 are made which neither change the meaning of the document
2884 nor affect the contents of packages.
2888 Thus only the first three components of the policy version
2889 are significant in the <em>Standards-Version</em> control
2890 field, and so either these three components or all four
2891 components may be specified.<footnote>
2892 In the past, people specified the full version number
2893 in the Standards-Version field, for example "2.3.0.0".
2894 Since minor patch-level changes don't introduce new
2895 policy, it was thought it would be better to relax
2896 policy and only require the first 3 components to be
2897 specified, in this example "2.3.0". All four
2898 components may still be used if someone wishes to do so.
2904 <sect1 id="f-Version">
2905 <heading><tt>Version</tt></heading>
2908 The version number of a package. The format is:
2909 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2913 The three components here are:
2915 <tag><var>epoch</var></tag>
2918 This is a single (generally small) unsigned integer. It
2919 may be omitted, in which case zero is assumed. If it is
2920 omitted then the <var>upstream_version</var> may not
2925 It is provided to allow mistakes in the version numbers
2926 of older versions of a package, and also a package's
2927 previous version numbering schemes, to be left behind.
2931 <tag><var>upstream_version</var></tag>
2934 This is the main part of the version number. It is
2935 usually the version number of the original ("upstream")
2936 package from which the <file>.deb</file> file has been made,
2937 if this is applicable. Usually this will be in the same
2938 format as that specified by the upstream author(s);
2939 however, it may need to be reformatted to fit into the
2940 package management system's format and comparison
2945 The comparison behavior of the package management system
2946 with respect to the <var>upstream_version</var> is
2947 described below. The <var>upstream_version</var>
2948 portion of the version number is mandatory.
2952 The <var>upstream_version</var> may contain only
2953 alphanumerics<footnote>
2954 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2956 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2957 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2958 tilde) and should start with a digit. If there is no
2959 <var>debian_revision</var> then hyphens are not allowed;
2960 if there is no <var>epoch</var> then colons are not
2965 <tag><var>debian_revision</var></tag>
2968 This part of the version number specifies the version of
2969 the Debian package based on the upstream version. It
2970 may contain only alphanumerics and the characters
2971 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2972 tilde) and is compared in the same way as the
2973 <var>upstream_version</var> is.
2977 It is optional; if it isn't present then the
2978 <var>upstream_version</var> may not contain a hyphen.
2979 This format represents the case where a piece of
2980 software was written specifically to be turned into a
2981 Debian package, and so there is only one "debianisation"
2982 of it and therefore no revision indication is required.
2986 It is conventional to restart the
2987 <var>debian_revision</var> at <tt>1</tt> each time the
2988 <var>upstream_version</var> is increased.
2992 The package management system will break the version
2993 number apart at the last hyphen in the string (if there
2994 is one) to determine the <var>upstream_version</var> and
2995 <var>debian_revision</var>. The absence of a
2996 <var>debian_revision</var> is equivalent to a
2997 <var>debian_revision</var> of <tt>0</tt>.
3004 When comparing two version numbers, first the <var>epoch</var>
3005 of each are compared, then the <var>upstream_version</var> if
3006 <var>epoch</var> is equal, and then <var>debian_revision</var>
3007 if <var>upstream_version</var> is also equal.
3008 <var>epoch</var> is compared numerically. The
3009 <var>upstream_version</var> and <var>debian_revision</var>
3010 parts are compared by the package management system using the
3011 following algorithm:
3015 The strings are compared from left to right.
3019 First the initial part of each string consisting entirely of
3020 non-digit characters is determined. These two parts (one of
3021 which may be empty) are compared lexically. If a difference
3022 is found it is returned. The lexical comparison is a
3023 comparison of ASCII values modified so that all the letters
3024 sort earlier than all the non-letters and so that a tilde
3025 sorts before anything, even the end of a part. For example,
3026 the following parts are in sorted order from earliest to
3027 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3028 <tt>a</tt>.<footnote>
3029 One common use of <tt>~</tt> is for upstream pre-releases.
3030 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3031 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3036 Then the initial part of the remainder of each string which
3037 consists entirely of digit characters is determined. The
3038 numerical values of these two parts are compared, and any
3039 difference found is returned as the result of the comparison.
3040 For these purposes an empty string (which can only occur at
3041 the end of one or both version strings being compared) counts
3046 These two steps (comparing and removing initial non-digit
3047 strings and initial digit strings) are repeated until a
3048 difference is found or both strings are exhausted.
3052 Note that the purpose of epochs is to allow us to leave behind
3053 mistakes in version numbering, and to cope with situations
3054 where the version numbering scheme changes. It is
3055 <em>not</em> intended to cope with version numbers containing
3056 strings of letters which the package management system cannot
3057 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3058 silly orderings (the author of this manual has heard of a
3059 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3060 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3061 <tt>2</tt> and so forth).
3065 <sect1 id="f-Description">
3066 <heading><tt>Description</tt></heading>
3069 In a source or binary control file, the <tt>Description</tt>
3070 field contains a description of the binary package, consisting
3071 of two parts, the synopsis or the short description, and the
3072 long description. The field's format is as follows:
3077 Description: <single line synopsis>
3078 <extended description over several lines>
3083 The lines in the extended description can have these formats:
3089 Those starting with a single space are part of a paragraph.
3090 Successive lines of this form will be word-wrapped when
3091 displayed. The leading space will usually be stripped off.
3095 Those starting with two or more spaces. These will be
3096 displayed verbatim. If the display cannot be panned
3097 horizontally, the displaying program will line wrap them "hard"
3098 (i.e., without taking account of word breaks). If it can they
3099 will be allowed to trail off to the right. None, one or two
3100 initial spaces may be deleted, but the number of spaces
3101 deleted from each line will be the same (so that you can have
3102 indenting work correctly, for example).
3106 Those containing a single space followed by a single full stop
3107 character. These are rendered as blank lines. This is the
3108 <em>only</em> way to get a blank line<footnote>
3109 Completely empty lines will not be rendered as blank lines.
3110 Instead, they will cause the parser to think you're starting
3111 a whole new record in the control file, and will therefore
3112 likely abort with an error.
3117 Those containing a space, a full stop and some more characters.
3118 These are for future expansion. Do not use them.
3124 Do not use tab characters. Their effect is not predictable.
3128 See <ref id="descriptions"> for further information on this.
3132 In a <file>.changes</file> file, the <tt>Description</tt>
3133 field contains a summary of the descriptions for the packages
3134 being uploaded. For this case, the first line of the field
3135 value (the part on the same line as <tt>Description:</tt>) is
3136 always empty. The content of the field is expressed as
3137 continuation lines, one line per package. Each line is
3138 indented by one space and contains the name of a binary
3139 package, a space, a hyphen (<tt>-</tt>), a space, and the
3140 short description line from that package.
3144 <sect1 id="f-Distribution">
3145 <heading><tt>Distribution</tt></heading>
3148 In a <file>.changes</file> file or parsed changelog output
3149 this contains the (space-separated) name(s) of the
3150 distribution(s) where this version of the package should
3151 be installed. Valid distributions are determined by the
3152 archive maintainers.<footnote>
3153 Example distribution names in the Debian archive used in
3154 <file>.changes</file> files are:
3155 <taglist compact="compact">
3156 <tag><em>unstable</em></tag>
3158 This distribution value refers to the
3159 <em>developmental</em> part of the Debian distribution
3160 tree. Most new packages, new upstream versions of
3161 packages and bug fixes go into the <em>unstable</em>
3165 <tag><em>experimental</em></tag>
3167 The packages with this distribution value are deemed
3168 by their maintainers to be high risk. Oftentimes they
3169 represent early beta or developmental packages from
3170 various sources that the maintainers want people to
3171 try, but are not ready to be a part of the other parts
3172 of the Debian distribution tree.
3177 Others are used for updating stable releases or for
3178 security uploads. More information is available in the
3179 Debian Developer's Reference, section "The Debian
3183 The Debian archive software only supports listing a single
3184 distribution. Migration of packages to other distributions is
3185 handled outside of the upload process.
3190 <heading><tt>Date</tt></heading>
3193 This field includes the date the package was built or last edited.
3197 The value of this field is usually extracted from the
3198 <file>debian/changelog</file> file - see
3199 <ref id="dpkgchangelog">).
3203 <sect1 id="f-Format">
3204 <heading><tt>Format</tt></heading>
3207 This field specifies a format revision for the file.
3208 The most current format described in the Policy Manual
3209 is version <strong>1.5</strong>. The syntax of the
3210 format value is the same as that of a package version
3211 number except that no epoch or Debian revision is allowed
3212 - see <ref id="f-Version">.
3216 <sect1 id="f-Urgency">
3217 <heading><tt>Urgency</tt></heading>
3220 This is a description of how important it is to upgrade to
3221 this version from previous ones. It consists of a single
3222 keyword taking one of the values <tt>low</tt>,
3223 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3224 <tt>critical</tt><footnote>
3225 Other urgency values are supported with configuration
3226 changes in the archive software but are not used in Debian.
3227 The urgency affects how quickly a package will be considered
3228 for inclusion into the <tt>testing</tt> distribution and
3229 gives an indication of the importance of any fixes included
3230 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3231 treated as synonymous.
3232 </footnote> (not case-sensitive) followed by an optional
3233 commentary (separated by a space) which is usually in
3234 parentheses. For example:
3237 Urgency: low (HIGH for users of diversions)
3243 The value of this field is usually extracted from the
3244 <file>debian/changelog</file> file - see
3245 <ref id="dpkgchangelog">.
3249 <sect1 id="f-Changes">
3250 <heading><tt>Changes</tt></heading>
3253 This field contains the human-readable changes data, describing
3254 the differences between the last version and the current one.
3258 The first line of the field value (the part on the same line
3259 as <tt>Changes:</tt>) is always empty. The content of the
3260 field is expressed as continuation lines, with each line
3261 indented by at least one space. Blank lines must be
3262 represented by a line consisting only of a space and a full
3267 The value of this field is usually extracted from the
3268 <file>debian/changelog</file> file - see
3269 <ref id="dpkgchangelog">).
3273 Each version's change information should be preceded by a
3274 "title" line giving at least the version, distribution(s)
3275 and urgency, in a human-readable way.
3279 If data from several versions is being returned the entry
3280 for the most recent version should be returned first, and
3281 entries should be separated by the representation of a
3282 blank line (the "title" line may also be followed by the
3283 representation of a blank line).
3287 <sect1 id="f-Binary">
3288 <heading><tt>Binary</tt></heading>
3291 This field is a list of binary packages. Its syntax and
3292 meaning varies depending on the control file in which it
3297 When it appears in the <file>.dsc</file> file, it lists binary
3298 packages which a source package can produce, separated by
3300 A space after each comma is conventional.
3301 </footnote>. It may span multiple lines. The source package
3302 does not necessarily produce all of these binary packages for
3303 every architecture. The source control file doesn't contain
3304 details of which architectures are appropriate for which of
3305 the binary packages.
3309 When it appears in a <file>.changes</file> file, it lists the
3310 names of the binary packages being uploaded, separated by
3311 whitespace (not commas). It may span multiple lines.
3315 <sect1 id="f-Installed-Size">
3316 <heading><tt>Installed-Size</tt></heading>
3319 This field appears in the control files of binary packages,
3320 and in the <file>Packages</file> files. It gives an estimate
3321 of the total amount of disk space required to install the
3322 named package. Actual installed size may vary based on block
3323 size, file system properties, or actions taken by package
3328 The disk space is given as the integer value of the estimated
3329 installed size in bytes, divided by 1024 and rounded up.
3333 <sect1 id="f-Files">
3334 <heading><tt>Files</tt></heading>
3337 This field contains a list of files with information about
3338 each one. The exact information and syntax varies with
3343 In all cases, Files is a multiline field. The first line of
3344 the field value (the part on the same line as <tt>Files:</tt>)
3345 is always empty. The content of the field is expressed as
3346 continuation lines, one line per file. Each line must be
3347 indented by one space and contain a number of sub-fields,
3348 separated by spaces, as described below.
3352 In the <file>.dsc</file> file, each line contains the MD5
3353 checksum, size and filename of the tar file and (if
3354 applicable) diff file which make up the remainder of the
3355 source package<footnote>
3356 That is, the parts which are not the <tt>.dsc</tt>.
3357 </footnote>. For example:
3360 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3361 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3363 The exact forms of the filenames are described
3364 in <ref id="pkg-sourcearchives">.
3368 In the <file>.changes</file> file this contains one line per
3369 file being uploaded. Each line contains the MD5 checksum,
3370 size, section and priority and the filename. For example:
3373 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3374 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3375 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3376 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3378 The <qref id="f-Section">section</qref>
3379 and <qref id="f-Priority">priority</qref> are the values of
3380 the corresponding fields in the main source control file. If
3381 no section or priority is specified then <tt>-</tt> should be
3382 used, though section and priority values must be specified for
3383 new packages to be installed properly.
3387 The special value <tt>byhand</tt> for the section in a
3388 <tt>.changes</tt> file indicates that the file in question
3389 is not an ordinary package file and must by installed by
3390 hand by the distribution maintainers. If the section is
3391 <tt>byhand</tt> the priority should be <tt>-</tt>.
3395 If a new Debian revision of a package is being shipped and
3396 no new original source archive is being distributed the
3397 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3398 entry for the original source archive
3399 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3400 but the <file>.changes</file> file should leave it out. In
3401 this case the original source archive on the distribution
3402 site must match exactly, byte-for-byte, the original
3403 source archive which was used to generate the
3404 <file>.dsc</file> file and diff which are being uploaded.</p>
3407 <sect1 id="f-Closes">
3408 <heading><tt>Closes</tt></heading>
3411 A space-separated list of bug report numbers that the upload
3412 governed by the .changes file closes.
3416 <sect1 id="f-Homepage">
3417 <heading><tt>Homepage</tt></heading>
3420 The URL of the web site for this package, preferably (when
3421 applicable) the site from which the original source can be
3422 obtained and any additional upstream documentation or
3423 information may be found. The content of this field is a
3424 simple URL without any surrounding characters such as
3432 <heading>User-defined fields</heading>
3435 Additional user-defined fields may be added to the
3436 source package control file. Such fields will be
3437 ignored, and not copied to (for example) binary or
3438 source package control files or upload control files.
3442 If you wish to add additional unsupported fields to
3443 these output files you should use the mechanism
3448 Fields in the main source control information file with
3449 names starting <tt>X</tt>, followed by one or more of
3450 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3451 be copied to the output files. Only the part of the
3452 field name after the hyphen will be used in the output
3453 file. Where the letter <tt>B</tt> is used the field
3454 will appear in binary package control files, where the
3455 letter <tt>S</tt> is used in source package control
3456 files and where <tt>C</tt> is used in upload control
3457 (<tt>.changes</tt>) files.
3461 For example, if the main source information control file
3464 XBS-Comment: I stand between the candle and the star.
3466 then the binary and source package control files will contain the
3469 Comment: I stand between the candle and the star.
3478 <chapt id="maintainerscripts">
3479 <heading>Package maintainer scripts and installation procedure</heading>
3482 <heading>Introduction to package maintainer scripts</heading>
3485 It is possible to supply scripts as part of a package which
3486 the package management system will run for you when your
3487 package is installed, upgraded or removed.
3491 These scripts are the files <prgn>preinst</prgn>,
3492 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3493 <prgn>postrm</prgn> in the control area of the package.
3494 They must be proper executable files; if they are scripts
3495 (which is recommended), they must start with the usual
3496 <tt>#!</tt> convention. They should be readable and
3497 executable by anyone, and must not be world-writable.
3501 The package management system looks at the exit status from
3502 these scripts. It is important that they exit with a
3503 non-zero status if there is an error, so that the package
3504 management system can stop its processing. For shell
3505 scripts this means that you <em>almost always</em> need to
3506 use <tt>set -e</tt> (this is usually true when writing shell
3507 scripts, in fact). It is also important, of course, that
3508 they exit with a zero status if everything went well.
3512 Additionally, packages interacting with users using
3513 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3514 install a <prgn>config</prgn> script in the control area,
3515 see <ref id="maintscriptprompt"> for details.
3519 When a package is upgraded a combination of the scripts from
3520 the old and new packages is called during the upgrade
3521 procedure. If your scripts are going to be at all
3522 complicated you need to be aware of this, and may need to
3523 check the arguments to your scripts.
3527 Broadly speaking the <prgn>preinst</prgn> is called before
3528 (a particular version of) a package is installed, and the
3529 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3530 before (a version of) a package is removed and the
3531 <prgn>postrm</prgn> afterwards.
3535 Programs called from maintainer scripts should not normally
3536 have a path prepended to them. Before installation is
3537 started, the package management system checks to see if the
3538 programs <prgn>ldconfig</prgn>,
3539 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3540 and <prgn>update-rc.d</prgn> can be found via the
3541 <tt>PATH</tt> environment variable. Those programs, and any
3542 other program that one would expect to be in the
3543 <tt>PATH</tt>, should thus be invoked without an absolute
3544 pathname. Maintainer scripts should also not reset the
3545 <tt>PATH</tt>, though they might choose to modify it by
3546 prepending or appending package-specific directories. These
3547 considerations really apply to all shell scripts.</p>
3550 <sect id="idempotency">
3551 <heading>Maintainer scripts idempotency</heading>
3554 It is necessary for the error recovery procedures that the
3555 scripts be idempotent. This means that if it is run
3556 successfully, and then it is called again, it doesn't bomb
3557 out or cause any harm, but just ensures that everything is
3558 the way it ought to be. If the first call failed, or
3559 aborted half way through for some reason, the second call
3560 should merely do the things that were left undone the first
3561 time, if any, and exit with a success status if everything
3563 This is so that if an error occurs, the user interrupts
3564 <prgn>dpkg</prgn> or some other unforeseen circumstance
3565 happens you don't leave the user with a badly-broken
3566 package when <prgn>dpkg</prgn> attempts to repeat the
3572 <sect id="controllingterminal">
3573 <heading>Controlling terminal for maintainer scripts</heading>
3576 The maintainer scripts are guaranteed to run with a
3577 controlling terminal and can interact with the user.
3578 Because these scripts may be executed with standard output
3579 redirected into a pipe for logging purposes, Perl scripts
3580 should set unbuffered output by setting <tt>$|=1</tt> so
3581 that the output is printed immediately rather than being
3585 <sect id="exitstatus">
3586 <heading>Exit status</heading>
3589 Each script must return a zero exit status for
3590 success, or a nonzero one for failure, since the package
3591 management system looks for the exit status of these scripts
3592 and determines what action to take next based on that datum.
3596 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3601 <list compact="compact">
3603 <var>new-preinst</var> <tt>install</tt>
3606 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3609 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3612 <var>old-preinst</var> <tt>abort-upgrade</tt>
3613 <var>new-version</var>
3618 <list compact="compact">
3620 <var>postinst</var> <tt>configure</tt>
3621 <var>most-recently-configured-version</var>
3624 <var>old-postinst</var> <tt>abort-upgrade</tt>
3625 <var>new-version</var>
3628 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3629 <tt>in-favour</tt> <var>package</var>
3630 <var>new-version</var>
3633 <var>postinst</var> <tt>abort-remove</tt>
3636 <var>deconfigured's-postinst</var>
3637 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3638 <var>failed-install-package</var> <var>version</var>
3639 [<tt>removing</tt> <var>conflicting-package</var>
3645 <list compact="compact">
3647 <var>prerm</var> <tt>remove</tt>
3650 <var>old-prerm</var> <tt>upgrade</tt>
3651 <var>new-version</var>
3654 <var>new-prerm</var> <tt>failed-upgrade</tt>
3655 <var>old-version</var>
3658 <var>conflictor's-prerm</var> <tt>remove</tt>
3659 <tt>in-favour</tt> <var>package</var>
3660 <var>new-version</var>
3663 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3664 <tt>in-favour</tt> <var>package-being-installed</var>
3665 <var>version</var> [<tt>removing</tt>
3666 <var>conflicting-package</var>
3672 <list compact="compact">
3674 <var>postrm</var> <tt>remove</tt>
3677 <var>postrm</var> <tt>purge</tt>
3680 <var>old-postrm</var> <tt>upgrade</tt>
3681 <var>new-version</var>
3684 <var>new-postrm</var> <tt>failed-upgrade</tt>
3685 <var>old-version</var>
3688 <var>new-postrm</var> <tt>abort-install</tt>
3691 <var>new-postrm</var> <tt>abort-install</tt>
3692 <var>old-version</var>
3695 <var>new-postrm</var> <tt>abort-upgrade</tt>
3696 <var>old-version</var>
3699 <var>disappearer's-postrm</var> <tt>disappear</tt>
3700 <var>overwriter</var>
3701 <var>overwriter-version</var>
3707 <sect id="unpackphase">
3708 <heading>Details of unpack phase of installation or upgrade</heading>
3711 The procedure on installation/upgrade/overwrite/disappear
3712 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3713 stage of <tt>dpkg --install</tt>) is as follows. In each
3714 case, if a major error occurs (unless listed below) the
3715 actions are, in general, run backwards - this means that the
3716 maintainer scripts are run with different arguments in
3717 reverse order. These are the "error unwind" calls listed
3724 If a version of the package is already installed, call
3725 <example compact="compact">
3726 <var>old-prerm</var> upgrade <var>new-version</var>
3730 If the script runs but exits with a non-zero
3731 exit status, <prgn>dpkg</prgn> will attempt:
3732 <example compact="compact">
3733 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3735 If this works, the upgrade continues. If this
3736 does not work, the error unwind:
3737 <example compact="compact">
3738 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3740 If this works, then the old-version is
3741 "Installed", if not, the old version is in a
3742 "Half-Configured" state.
3748 If a "conflicting" package is being removed at the same time,
3749 or if any package will be broken (due to <tt>Breaks</tt>):
3752 If <tt>--auto-deconfigure</tt> is
3753 specified, call, for each package to be deconfigured
3754 due to <tt>Breaks</tt>:
3755 <example compact="compact">
3756 <var>deconfigured's-prerm</var> deconfigure \
3757 in-favour <var>package-being-installed</var> <var>version</var>
3760 <example compact="compact">
3761 <var>deconfigured's-postinst</var> abort-deconfigure \
3762 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3764 The deconfigured packages are marked as
3765 requiring configuration, so that if
3766 <tt>--install</tt> is used they will be
3767 configured again if possible.
3770 If any packages depended on a conflicting
3771 package being removed and <tt>--auto-deconfigure</tt> is
3772 specified, call, for each such package:
3773 <example compact="compact">
3774 <var>deconfigured's-prerm</var> deconfigure \
3775 in-favour <var>package-being-installed</var> <var>version</var> \
3776 removing <var>conflicting-package</var> <var>version</var>
3779 <example compact="compact">
3780 <var>deconfigured's-postinst</var> abort-deconfigure \
3781 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3782 removing <var>conflicting-package</var> <var>version</var>
3784 The deconfigured packages are marked as
3785 requiring configuration, so that if
3786 <tt>--install</tt> is used they will be
3787 configured again if possible.
3790 To prepare for removal of each conflicting package, call:
3791 <example compact="compact">
3792 <var>conflictor's-prerm</var> remove \
3793 in-favour <var>package</var> <var>new-version</var>
3796 <example compact="compact">
3797 <var>conflictor's-postinst</var> abort-remove \
3798 in-favour <var>package</var> <var>new-version</var>
3807 If the package is being upgraded, call:
3808 <example compact="compact">
3809 <var>new-preinst</var> upgrade <var>old-version</var>
3811 If this fails, we call:
3813 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3820 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3822 is called. If this works, then the old version
3823 is in an "Installed" state, or else it is left
3824 in an "Unpacked" state.
3829 If it fails, then the old version is left
3830 in an "Half-Installed" state.
3837 Otherwise, if the package had some configuration
3838 files from a previous version installed (i.e., it
3839 is in the "configuration files only" state):
3840 <example compact="compact">
3841 <var>new-preinst</var> install <var>old-version</var>
3845 <var>new-postrm</var> abort-install <var>old-version</var>
3847 If this fails, the package is left in a
3848 "Half-Installed" state, which requires a
3849 reinstall. If it works, the packages is left in
3850 a "Config-Files" state.
3853 Otherwise (i.e., the package was completely purged):
3854 <example compact="compact">
3855 <var>new-preinst</var> install
3858 <example compact="compact">
3859 <var>new-postrm</var> abort-install
3861 If the error-unwind fails, the package is in a
3862 "Half-Installed" phase, and requires a
3863 reinstall. If the error unwind works, the
3864 package is in a not installed state.
3871 The new package's files are unpacked, overwriting any
3872 that may be on the system already, for example any
3873 from the old version of the same package or from
3874 another package. Backups of the old files are kept
3875 temporarily, and if anything goes wrong the package
3876 management system will attempt to put them back as
3877 part of the error unwind.
3881 It is an error for a package to contain files which
3882 are on the system in another package, unless
3883 <tt>Replaces</tt> is used (see <ref id="replaces">).
3885 The following paragraph is not currently the case:
3886 Currently the <tt>- - force-overwrite</tt> flag is
3887 enabled, downgrading it to a warning, but this may not
3893 It is a more serious error for a package to contain a
3894 plain file or other kind of non-directory where another
3895 package has a directory (again, unless
3896 <tt>Replaces</tt> is used). This error can be
3897 overridden if desired using
3898 <tt>--force-overwrite-dir</tt>, but this is not
3903 Packages which overwrite each other's files produce
3904 behavior which, though deterministic, is hard for the
3905 system administrator to understand. It can easily
3906 lead to "missing" programs if, for example, a package
3907 is installed which overwrites a file from another
3908 package, and is then removed again.<footnote>
3909 Part of the problem is due to what is arguably a
3910 bug in <prgn>dpkg</prgn>.
3915 A directory will never be replaced by a symbolic link
3916 to a directory or vice versa; instead, the existing
3917 state (symlink or not) will be left alone and
3918 <prgn>dpkg</prgn> will follow the symlink if there is
3927 If the package is being upgraded, call
3928 <example compact="compact">
3929 <var>old-postrm</var> upgrade <var>new-version</var>
3933 If this fails, <prgn>dpkg</prgn> will attempt:
3934 <example compact="compact">
3935 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3937 If this works, installation continues. If not,
3939 <example compact="compact">
3940 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3942 If this fails, the old version is left in a
3943 "Half-Installed" state. If it works, dpkg now
3945 <example compact="compact">
3946 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3948 If this fails, the old version is left in a
3949 "Half-Installed" state. If it works, dpkg now
3951 <example compact="compact">
3952 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3954 If this fails, the old version is in an
3961 This is the point of no return - if
3962 <prgn>dpkg</prgn> gets this far, it won't back off
3963 past this point if an error occurs. This will
3964 leave the package in a fairly bad state, which
3965 will require a successful re-installation to clear
3966 up, but it's when <prgn>dpkg</prgn> starts doing
3967 things that are irreversible.
3972 Any files which were in the old version of the package
3973 but not in the new are removed.
3977 The new file list replaces the old.
3981 The new maintainer scripts replace the old.
3985 Any packages all of whose files have been overwritten
3986 during the installation, and which aren't required for
3987 dependencies, are considered to have been removed.
3988 For each such package
3991 <prgn>dpkg</prgn> calls:
3992 <example compact="compact">
3993 <var>disappearer's-postrm</var> disappear \
3994 <var>overwriter</var> <var>overwriter-version</var>
3998 The package's maintainer scripts are removed.
4001 It is noted in the status database as being in a
4002 sane state, namely not installed (any conffiles
4003 it may have are ignored, rather than being
4004 removed by <prgn>dpkg</prgn>). Note that
4005 disappearing packages do not have their prerm
4006 called, because <prgn>dpkg</prgn> doesn't know
4007 in advance that the package is going to
4014 Any files in the package we're unpacking that are also
4015 listed in the file lists of other packages are removed
4016 from those lists. (This will lobotomize the file list
4017 of the "conflicting" package if there is one.)
4021 The backup files made during installation, above, are
4027 The new package's status is now sane, and recorded as
4032 Here is another point of no return - if the
4033 conflicting package's removal fails we do not unwind
4034 the rest of the installation; the conflicting package
4035 is left in a half-removed limbo.
4040 If there was a conflicting package we go and do the
4041 removal actions (described below), starting with the
4042 removal of the conflicting package's files (any that
4043 are also in the package being installed have already
4044 been removed from the conflicting package's file list,
4045 and so do not get removed now).
4051 <sect id="configdetails"><heading>Details of configuration</heading>
4054 When we configure a package (this happens with <tt>dpkg
4055 --install</tt> and <tt>dpkg --configure</tt>), we first
4056 update any <tt>conffile</tt>s and then call:
4057 <example compact="compact">
4058 <var>postinst</var> configure <var>most-recently-configured-version</var>
4063 No attempt is made to unwind after errors during
4064 configuration. If the configuration fails, the package is in
4065 a "Failed Config" state, and an error message is generated.
4069 If there is no most recently configured version
4070 <prgn>dpkg</prgn> will pass a null argument.
4073 Historical note: Truly ancient (pre-1997) versions of
4074 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4075 (including the angle brackets) in this case. Even older
4076 ones did not pass a second argument at all, under any
4077 circumstance. Note that upgrades using such an old dpkg
4078 version are unlikely to work for other reasons, even if
4079 this old argument behavior is handled by your postinst script.
4085 <sect id="removedetails"><heading>Details of removal and/or
4086 configuration purging</heading>
4092 <example compact="compact">
4093 <var>prerm</var> remove
4097 If prerm fails during replacement due to conflict
4099 <var>conflictor's-postinst</var> abort-remove \
4100 in-favour <var>package</var> <var>new-version</var>
4104 <var>postinst</var> abort-remove
4108 If this fails, the package is in a "Half-Configured"
4109 state, or else it remains "Installed".
4113 The package's files are removed (except <tt>conffile</tt>s).
4116 <example compact="compact">
4117 <var>postrm</var> remove
4121 If it fails, there's no error unwind, and the package is in
4122 an "Half-Installed" state.
4127 All the maintainer scripts except the <prgn>postrm</prgn>
4132 If we aren't purging the package we stop here. Note
4133 that packages which have no <prgn>postrm</prgn> and no
4134 <tt>conffile</tt>s are automatically purged when
4135 removed, as there is no difference except for the
4136 <prgn>dpkg</prgn> status.
4140 The <tt>conffile</tt>s and any backup files
4141 (<tt>~</tt>-files, <tt>#*#</tt> files,
4142 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4147 <example compact="compact">
4148 <var>postrm</var> purge
4152 If this fails, the package remains in a "Config-Files"
4157 The package's file list is removed.
4166 <chapt id="relationships">
4167 <heading>Declaring relationships between packages</heading>
4169 <sect id="depsyntax">
4170 <heading>Syntax of relationship fields</heading>
4173 These fields all have a uniform syntax. They are a list of
4174 package names separated by commas.
4178 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4179 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4180 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4181 control file fields of the package, which declare
4182 dependencies on other packages, the package names listed may
4183 also include lists of alternative package names, separated
4184 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4185 if any one of the alternative packages is installed, that
4186 part of the dependency is considered to be satisfied.
4190 All of the fields except for <tt>Provides</tt> may restrict
4191 their applicability to particular versions of each named
4192 package. This is done in parentheses after each individual
4193 package name; the parentheses should contain a relation from
4194 the list below followed by a version number, in the format
4195 described in <ref id="f-Version">.
4199 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4200 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4201 strictly earlier, earlier or equal, exactly equal, later or
4202 equal and strictly later, respectively. The deprecated
4203 forms <tt><</tt> and <tt>></tt> were used to mean
4204 earlier/later or equal, rather than strictly earlier/later,
4205 so they should not appear in new packages (though
4206 <prgn>dpkg</prgn> still supports them).
4210 Whitespace may appear at any point in the version
4211 specification subject to the rules in <ref
4212 id="controlsyntax">, and must appear where it's necessary to
4213 disambiguate; it is not otherwise significant. All of the
4214 relationship fields may span multiple lines. For
4215 consistency and in case of future changes to
4216 <prgn>dpkg</prgn> it is recommended that a single space be
4217 used after a version relationship and before a version
4218 number; it is also conventional to put a single space after
4219 each comma, on either side of each vertical bar, and before
4220 each open parenthesis. When wrapping a relationship field, it
4221 is conventional to do so after a comma and before the space
4222 following that comma.
4226 For example, a list of dependencies might appear as:
4227 <example compact="compact">
4230 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4235 All fields that specify build-time relationships
4236 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4237 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4238 may be restricted to a certain set of architectures. This
4239 is indicated in brackets after each individual package name and
4240 the optional version specification. The brackets enclose a
4241 list of Debian architecture names separated by whitespace.
4242 Exclamation marks may be prepended to each of the names.
4243 (It is not permitted for some names to be prepended with
4244 exclamation marks while others aren't.) If the current Debian
4245 host architecture is not in this list and there are no
4246 exclamation marks in the list, or it is in the list with a
4247 prepended exclamation mark, the package name and the
4248 associated version specification are ignored completely for
4249 the purposes of defining the relationships.
4254 <example compact="compact">
4256 Build-Depends-Indep: texinfo
4257 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4258 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4260 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4261 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4262 <tt>gnumach-dev</tt> only on hurd-i386.
4266 If the architecture-restricted dependency is part of a set of
4267 alternatives using <tt>|</tt>, that alternative is ignored
4268 completely on architectures that do not match the restriction.
4270 <example compact="compact">
4271 Build-Depends: foo [!i386] | bar [!amd64]
4273 is equivalent to <tt>bar</tt> on the i386 architecture, to
4274 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4275 bar</tt> on all other architectures.
4279 Note that the binary package relationship fields such as
4280 <tt>Depends</tt> appear in one of the binary package
4281 sections of the control file, whereas the build-time
4282 relationships such as <tt>Build-Depends</tt> appear in the
4283 source package section of the control file (which is the
4287 All fields that specify build-time relationships
4288 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4289 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>) may also
4290 be restricted to a certain set of architectures using architecture
4291 wildcards. The syntax for declaring such restrictions is the same as
4292 declaring restrictions using a certain set of architectures without
4293 architecture wildcards.
4295 <example compact="compact">
4296 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4298 is equivalent to <tt>foo</tt> on architectures using the
4299 Linux kernel and any cpu, <tt>bar</tt> on architectures
4300 using any kernel and an i386 cpu, and <tt>baz</tt> on
4301 on any architecture using a kernel other than Linux.
4305 <sect id="binarydeps">
4306 <heading>Binary Dependencies - <tt>Depends</tt>,
4307 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4308 <tt>Pre-Depends</tt>
4312 Packages can declare in their control file that they have
4313 certain relationships to other packages - for example, that
4314 they may not be installed at the same time as certain other
4315 packages, and/or that they depend on the presence of others.
4319 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4320 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4321 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4322 <tt>Breaks</tt> is described in <ref id="breaks">, and
4323 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4324 rest are described below.
4328 These seven fields are used to declare a dependency
4329 relationship by one package on another. Except for
4330 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4331 depending (binary) package's control file.
4332 (<tt>Enhances</tt> appears in the recommending package's
4333 control file, and <tt>Breaks</tt> appears in the version of
4334 depended-on package which causes the named package to
4339 A <tt>Depends</tt> field takes effect <em>only</em> when a
4340 package is to be configured. It does not prevent a package
4341 being on the system in an unconfigured state while its
4342 dependencies are unsatisfied, and it is possible to replace
4343 a package whose dependencies are satisfied and which is
4344 properly installed with a different version whose
4345 dependencies are not and cannot be satisfied; when this is
4346 done the depending package will be left unconfigured (since
4347 attempts to configure it will give errors) and will not
4348 function properly. If it is necessary, a
4349 <tt>Pre-Depends</tt> field can be used, which has a partial
4350 effect even when a package is being unpacked, as explained
4351 in detail below. (The other three dependency fields,
4352 <tt>Recommends</tt>, <tt>Suggests</tt> and
4353 <tt>Enhances</tt>, are only used by the various front-ends
4354 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4355 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4359 For this reason packages in an installation run are usually
4360 all unpacked first and all configured later; this gives
4361 later versions of packages with dependencies on later
4362 versions of other packages the opportunity to have their
4363 dependencies satisfied.
4367 In case of circular dependencies, since installation or
4368 removal order honoring the dependency order can't be
4369 established, dependency loops are broken at some point
4370 (based on rules below), and some packages may not be able to
4371 rely on their dependencies being present when being
4372 installed or removed, depending on which side of the break
4373 of the circular dependency loop they happen to be on. If one
4374 of the packages in the loop has no postinst script, then the
4375 cycle will be broken at that package, so as to ensure that
4376 all postinst scripts run with the dependencies properly
4377 configured if this is possible. Otherwise the breaking point
4382 The <tt>Depends</tt> field thus allows package maintainers
4383 to impose an order in which packages should be configured.
4387 The meaning of the five dependency fields is as follows:
4389 <tag><tt>Depends</tt></tag>
4392 This declares an absolute dependency. A package will
4393 not be configured unless all of the packages listed in
4394 its <tt>Depends</tt> field have been correctly
4399 The <tt>Depends</tt> field should be used if the
4400 depended-on package is required for the depending
4401 package to provide a significant amount of
4406 The <tt>Depends</tt> field should also be used if the
4407 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4408 <prgn>postrm</prgn> scripts require the package to be
4409 present in order to run. Note, however, that the
4410 <prgn>postrm</prgn> cannot rely on any non-essential
4411 packages to be present during the <tt>purge</tt>
4415 <tag><tt>Recommends</tt></tag>
4418 This declares a strong, but not absolute, dependency.
4422 The <tt>Recommends</tt> field should list packages
4423 that would be found together with this one in all but
4424 unusual installations.
4428 <tag><tt>Suggests</tt></tag>
4430 This is used to declare that one package may be more
4431 useful with one or more others. Using this field
4432 tells the packaging system and the user that the
4433 listed packages are related to this one and can
4434 perhaps enhance its usefulness, but that installing
4435 this one without them is perfectly reasonable.
4438 <tag><tt>Enhances</tt></tag>
4440 This field is similar to Suggests but works in the
4441 opposite direction. It is used to declare that a
4442 package can enhance the functionality of another
4446 <tag><tt>Pre-Depends</tt></tag>
4449 This field is like <tt>Depends</tt>, except that it
4450 also forces <prgn>dpkg</prgn> to complete installation
4451 of the packages named before even starting the
4452 installation of the package which declares the
4453 pre-dependency, as follows:
4457 When a package declaring a pre-dependency is about to
4458 be <em>unpacked</em> the pre-dependency can be
4459 satisfied if the depended-on package is either fully
4460 configured, <em>or even if</em> the depended-on
4461 package(s) are only unpacked or in the "Half-Configured"
4462 state, provided that they have been configured
4463 correctly at some point in the past (and not removed
4464 or partially removed since). In this case, both the
4465 previously-configured and currently unpacked or
4466 "Half-Configured" versions must satisfy any version
4467 clause in the <tt>Pre-Depends</tt> field.
4471 When the package declaring a pre-dependency is about
4472 to be <em>configured</em>, the pre-dependency will be
4473 treated as a normal <tt>Depends</tt>, that is, it will
4474 be considered satisfied only if the depended-on
4475 package has been correctly configured.
4479 <tt>Pre-Depends</tt> should be used sparingly,
4480 preferably only by packages whose premature upgrade or
4481 installation would hamper the ability of the system to
4482 continue with any upgrade that might be in progress.
4486 <tt>Pre-Depends</tt> are also required if the
4487 <prgn>preinst</prgn> script depends on the named
4488 package. It is best to avoid this situation if
4496 When selecting which level of dependency to use you should
4497 consider how important the depended-on package is to the
4498 functionality of the one declaring the dependency. Some
4499 packages are composed of components of varying degrees of
4500 importance. Such a package should list using
4501 <tt>Depends</tt> the package(s) which are required by the
4502 more important components. The other components'
4503 requirements may be mentioned as Suggestions or
4504 Recommendations, as appropriate to the components' relative
4510 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4513 When one binary package declares that it breaks another,
4514 <prgn>dpkg</prgn> will refuse to allow the package which
4515 declares <tt>Breaks</tt> be installed unless the broken
4516 package is deconfigured first, and it will refuse to
4517 allow the broken package to be reconfigured.
4521 A package will not be regarded as causing breakage merely
4522 because its configuration files are still installed; it must
4523 be at least "Half-Installed".
4527 A special exception is made for packages which declare that
4528 they break their own package name or a virtual package which
4529 they provide (see below): this does not count as a real
4534 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4535 version clause; such a <tt>Breaks</tt> is introduced in the
4536 version of an (implicit or explicit) dependency which
4537 violates an assumption or reveals a bug in earlier versions
4538 of the broken package. This use of <tt>Breaks</tt> will
4539 inform higher-level package management tools that broken
4540 package must be upgraded before the new one.
4544 If the breaking package also overwrites some files from the
4545 older package, it should use <tt>Replaces</tt> (not
4546 <tt>Conflicts</tt>) to ensure this goes smoothly.
4550 <sect id="conflicts">
4551 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4554 When one binary package declares a conflict with another
4555 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4556 refuse to allow them to be installed on the system at the
4561 If one package is to be installed, the other must be removed
4562 first - if the package being installed is marked as
4563 replacing (see <ref id="replaces">) the one on the system,
4564 or the one on the system is marked as deselected, or both
4565 packages are marked <tt>Essential</tt>, then
4566 <prgn>dpkg</prgn> will automatically remove the package
4567 which is causing the conflict, otherwise it will halt the
4568 installation of the new package with an error. This
4569 mechanism is specifically designed to produce an error when
4570 the installed package is <tt>Essential</tt>, but the new
4575 A package will not cause a conflict merely because its
4576 configuration files are still installed; it must be at least
4581 A special exception is made for packages which declare a
4582 conflict with their own package name, or with a virtual
4583 package which they provide (see below): this does not
4584 prevent their installation, and allows a package to conflict
4585 with others providing a replacement for it. You use this
4586 feature when you want the package in question to be the only
4587 package providing some feature.
4591 A <tt>Conflicts</tt> entry should almost never have an
4592 "earlier than" version clause. This would prevent
4593 <prgn>dpkg</prgn> from upgrading or installing the package
4594 which declared such a conflict until the upgrade or removal
4595 of the conflicted-with package had been completed. Instead,
4596 <tt>Breaks</tt> may be used.
4600 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4604 As well as the names of actual ("concrete") packages, the
4605 package relationship fields <tt>Depends</tt>,
4606 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4607 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4608 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4609 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4610 may mention "virtual packages".
4614 A <em>virtual package</em> is one which appears in the
4615 <tt>Provides</tt> control file field of another package.
4616 The effect is as if the package(s) which provide a
4617 particular virtual package name had been listed by name
4618 everywhere the virtual package name appears. (See also <ref
4623 If there are both concrete and virtual packages of the same
4624 name, then the dependency may be satisfied (or the conflict
4625 caused) by either the concrete package with the name in
4626 question or any other concrete package which provides the
4627 virtual package with the name in question. This is so that,
4628 for example, supposing we have
4629 <example compact="compact">
4632 </example> and someone else releases an enhanced version of
4633 the <tt>bar</tt> package they can say:
4634 <example compact="compact">
4638 and the <tt>bar-plus</tt> package will now also satisfy the
4639 dependency for the <tt>foo</tt> package.
4643 If a relationship field has a version number attached
4644 then only real packages will be considered to see whether
4645 the relationship is satisfied (or the prohibition violated,
4646 for a conflict or breakage) - it is assumed that a real
4647 package which provides the virtual package is not of the
4648 "right" version. So, a <tt>Provides</tt> field may not
4649 contain version numbers, and the version number of the
4650 concrete package which provides a particular virtual package
4651 will not be looked at when considering a dependency on or
4652 conflict with the virtual package name.
4656 It is likely that the ability will be added in a future
4657 release of <prgn>dpkg</prgn> to specify a version number for
4658 each virtual package it provides. This feature is not yet
4659 present, however, and is expected to be used only
4664 If you want to specify which of a set of real packages
4665 should be the default to satisfy a particular dependency on
4666 a virtual package, you should list the real package as an
4667 alternative before the virtual one.
4672 <sect id="replaces"><heading>Overwriting files and replacing
4673 packages - <tt>Replaces</tt></heading>
4676 Packages can declare in their control file that they should
4677 overwrite files in certain other packages, or completely
4678 replace other packages. The <tt>Replaces</tt> control file
4679 field has these two distinct purposes.
4682 <sect1><heading>Overwriting files in other packages</heading>
4685 Firstly, as mentioned before, it is usually an error for a
4686 package to contain files which are on the system in
4691 However, if the overwriting package declares that it
4692 <tt>Replaces</tt> the one containing the file being
4693 overwritten, then <prgn>dpkg</prgn> will replace the file
4694 from the old package with that from the new. The file
4695 will no longer be listed as "owned" by the old package.
4699 If a package is completely replaced in this way, so that
4700 <prgn>dpkg</prgn> does not know of any files it still
4701 contains, it is considered to have "disappeared". It will
4702 be marked as not wanted on the system (selected for
4703 removal) and not installed. Any <tt>conffile</tt>s
4704 details noted for the package will be ignored, as they
4705 will have been taken over by the overwriting package. The
4706 package's <prgn>postrm</prgn> script will be run with a
4707 special argument to allow the package to do any final
4708 cleanup required. See <ref id="mscriptsinstact">.
4711 Replaces is a one way relationship -- you have to
4712 install the replacing package after the replaced
4719 For this usage of <tt>Replaces</tt>, virtual packages (see
4720 <ref id="virtual">) are not considered when looking at a
4721 <tt>Replaces</tt> field - the packages declared as being
4722 replaced must be mentioned by their real names.
4726 Furthermore, this usage of <tt>Replaces</tt> only takes
4727 effect when both packages are at least partially on the
4728 system at once, so that it can only happen if they do not
4729 conflict or if the conflict has been overridden.
4734 <sect1><heading>Replacing whole packages, forcing their
4738 Secondly, <tt>Replaces</tt> allows the packaging system to
4739 resolve which package should be removed when there is a
4740 conflict - see <ref id="conflicts">. This usage only
4741 takes effect when the two packages <em>do</em> conflict,
4742 so that the two usages of this field do not interfere with
4747 In this situation, the package declared as being replaced
4748 can be a virtual package, so for example, all mail
4749 transport agents (MTAs) would have the following fields in
4750 their control files:
4751 <example compact="compact">
4752 Provides: mail-transport-agent
4753 Conflicts: mail-transport-agent
4754 Replaces: mail-transport-agent
4756 ensuring that only one MTA can be installed at any one
4761 <sect id="sourcebinarydeps">
4762 <heading>Relationships between source and binary packages -
4763 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4764 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4768 Source packages that require certain binary packages to be
4769 installed or absent at the time of building the package
4770 can declare relationships to those binary packages.
4774 This is done using the <tt>Build-Depends</tt>,
4775 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4776 <tt>Build-Conflicts-Indep</tt> control file fields.
4780 Build-dependencies on "build-essential" binary packages can be
4781 omitted. Please see <ref id="pkg-relations"> for more information.
4785 The dependencies and conflicts they define must be satisfied
4786 (as defined earlier for binary packages) in order to invoke
4787 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4789 If you make "build-arch" or "binary-arch", you need
4790 Build-Depends. If you make "build-indep" or
4791 "binary-indep", you need Build-Depends and
4792 Build-Depends-Indep. If you make "build" or "binary",
4796 There is no Build-Depends-Arch; this role is essentially
4797 met with Build-Depends. Anyone building the
4798 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4799 is basically assumed to be building the whole package
4800 anyway and so installs all build dependencies. The
4801 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4802 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4803 does not yet know how to check for its existence) and
4804 <tt>binary-arch</tt>.
4807 The purpose of the original split, I recall, was so that
4808 the autobuilders wouldn't need to install extra packages
4809 needed only for the binary-indep targets. But without a
4810 build-arch/build-indep split, this didn't work, since
4811 most of the work is done in the build target, not in the
4817 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4819 The <tt>Build-Depends</tt> and
4820 <tt>Build-Conflicts</tt> fields must be satisfied when
4821 any of the following targets is invoked:
4822 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4823 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4824 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4826 <tag><tt>Build-Depends-Indep</tt>,
4827 <tt>Build-Conflicts-Indep</tt></tag>
4829 The <tt>Build-Depends-Indep</tt> and
4830 <tt>Build-Conflicts-Indep</tt> fields must be
4831 satisfied when any of the following targets is
4832 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4833 <tt>binary</tt> and <tt>binary-indep</tt>.
4843 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4846 Packages containing shared libraries must be constructed with
4847 a little care to make sure that the shared library is always
4848 available. This is especially important for packages whose
4849 shared libraries are vitally important, such as the C library
4850 (currently <tt>libc6</tt>).
4854 Packages involving shared libraries should be split up into
4855 several binary packages. This section mostly deals with how
4856 this separation is to be accomplished; rules for files within
4857 the shared library packages are in <ref id="libraries"> instead.
4860 <sect id="sharedlibs-runtime">
4861 <heading>Run-time shared libraries</heading>
4864 The run-time shared library needs to be placed in a package
4865 whose name changes whenever the shared object version
4868 Since it is common place to install several versions of a
4869 package that just provides shared libraries, it is a
4870 good idea that the library package should not
4871 contain any extraneous non-versioned files, unless they
4872 happen to be in versioned directories.</p>
4874 The most common mechanism is to place it in a package
4876 <package><var>libraryname</var><var>soversion</var></package>,
4877 where <file><var>soversion</var></file> is the version number
4878 in the soname of the shared library<footnote>
4879 The soname is the shared object name: it's the thing
4880 that has to match exactly between building an executable
4881 and running it for the dynamic linker to be able run the
4882 program. For example, if the soname of the library is
4883 <file>libfoo.so.6</file>, the library package would be
4884 called <file>libfoo6</file>.
4886 Alternatively, if it would be confusing to directly append
4887 <var>soversion</var> to <var>libraryname</var> (e.g. because
4888 <var>libraryname</var> itself ends in a number), you may use
4889 <package><var>libraryname</var>-<var>soversion</var></package> and
4890 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4895 If you have several shared libraries built from the same
4896 source tree you may lump them all together into a single
4897 shared library package, provided that you change all of
4898 their sonames at once (so that you don't get filename
4899 clashes if you try to install different versions of the
4900 combined shared libraries package).
4904 The package should install the shared libraries under
4905 their normal names. For example, the <package>libgdbm3</package>
4906 package should install <file>libgdbm.so.3.0.0</file> as
4907 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4908 renamed or re-linked by any <prgn>prerm</prgn> or
4909 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4910 of renaming things safely without affecting running programs,
4911 and attempts to interfere with this are likely to lead to
4916 Shared libraries should not be installed executable, since
4917 the dynamic linker does not require this and trying to
4918 execute a shared library usually results in a core dump.
4922 The run-time library package should include the symbolic link that
4923 <prgn>ldconfig</prgn> would create for the shared libraries.
4924 For example, the <package>libgdbm3</package> package should include
4925 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4926 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4927 linker (for example <prgn>ld.so</prgn> or
4928 <prgn>ld-linux.so.*</prgn>) can find the library between the
4929 time that <prgn>dpkg</prgn> installs it and the time that
4930 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4932 The package management system requires the library to be
4933 placed before the symbolic link pointing to it in the
4934 <file>.deb</file> file. This is so that when
4935 <prgn>dpkg</prgn> comes to install the symlink
4936 (overwriting the previous symlink pointing at an older
4937 version of the library), the new shared library is already
4938 in place. In the past, this was achieved by creating the
4939 library in the temporary packaging directory before
4940 creating the symlink. Unfortunately, this was not always
4941 effective, since the building of the tar file in the
4942 <file>.deb</file> depended on the behavior of the underlying
4943 file system. Some file systems (such as reiserfs) reorder
4944 the files so that the order of creation is forgotten.
4945 Since version 1.7.0, <prgn>dpkg</prgn>
4946 reorders the files itself as necessary when building a
4947 package. Thus it is no longer important to concern
4948 oneself with the order of file creation.
4952 <sect1 id="ldconfig">
4953 <heading><tt>ldconfig</tt></heading>
4956 Any package installing shared libraries in one of the default
4957 library directories of the dynamic linker (which are currently
4958 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4959 listed in <file>/etc/ld.so.conf</file><footnote>
4961 <list compact="compact">
4962 <item>/usr/local/lib</item>
4963 <item>/usr/lib/libc5-compat</item>
4964 <item>/lib/libc5-compat</item>
4967 must use <prgn>ldconfig</prgn> to update the shared library
4972 The package maintainer scripts must only call
4973 <prgn>ldconfig</prgn> under these circumstances:
4974 <list compact="compact">
4975 <item>When the <prgn>postinst</prgn> script is run with a
4976 first argument of <tt>configure</tt>, the script must call
4977 <prgn>ldconfig</prgn>, and may optionally invoke
4978 <prgn>ldconfig</prgn> at other times.
4980 <item>When the <prgn>postrm</prgn> script is run with a
4981 first argument of <tt>remove</tt>, the script should call
4982 <prgn>ldconfig</prgn>.
4987 During install or upgrade, the preinst is called before
4988 the new files are installed, so calling "ldconfig" is
4989 pointless. The preinst of an existing package can also be
4990 called if an upgrade fails. However, this happens during
4991 the critical time when a shared libs may exist on-disk
4992 under a temporary name. Thus, it is dangerous and
4993 forbidden by current policy to call "ldconfig" at this
4998 When a package is installed or upgraded, "postinst
4999 configure" runs after the new files are safely on-disk.
5000 Since it is perfectly safe to invoke ldconfig
5001 unconditionally in a postinst, it is OK for a package to
5002 simply put ldconfig in its postinst without checking the
5003 argument. The postinst can also be called to recover from
5004 a failed upgrade. This happens before any new files are
5005 unpacked, so there is no reason to call "ldconfig" at this
5010 For a package that is being removed, prerm is
5011 called with all the files intact, so calling ldconfig is
5012 useless. The other calls to "prerm" happen in the case of
5013 upgrade at a time when all the files of the old package
5014 are on-disk, so again calling "ldconfig" is pointless.
5018 postrm, on the other hand, is called with the "remove"
5019 argument just after the files are removed, so this is
5020 the proper time to call "ldconfig" to notify the system
5021 of the fact that the shared libraries from the package
5022 are removed. The postrm can be called at several other
5023 times. At the time of "postrm purge", "postrm
5024 abort-install", or "postrm abort-upgrade", calling
5025 "ldconfig" is useless because the shared lib files are
5026 not on-disk. However, when "postrm" is invoked with
5027 arguments "upgrade", "failed-upgrade", or "disappear", a
5028 shared lib may exist on-disk under a temporary filename.
5036 <sect id="sharedlibs-support-files">
5037 <heading>Shared library support files</heading>
5040 If your package contains files whose names do not change with
5041 each change in the library shared object version, you must not
5042 put them in the shared library package. Otherwise, several
5043 versions of the shared library cannot be installed at the same
5044 time without filename clashes, making upgrades and transitions
5045 unnecessarily difficult.
5049 It is recommended that supporting files and run-time support
5050 programs that do not need to be invoked manually by users, but
5051 are nevertheless required for the package to function, be placed
5052 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5053 preferably under <file>/usr/lib/</file><var>package-name</var>.
5054 If the program or file is architecture independent, the
5055 recommendation is for it to be placed in a subdirectory of
5056 <file>/usr/share</file> instead, preferably under
5057 <file>/usr/share/</file><var>package-name</var>. Following the
5058 <var>package-name</var> naming convention ensures that the file
5059 names change when the shared object version changes.
5063 Run-time support programs that use the shared library but are
5064 not required for the library to function or files used by the
5065 shared library that can be used by any version of the shared
5066 library package should instead be put in a separate package.
5067 This package might typically be named
5068 <package><var>libraryname</var>-tools</package>; note the
5069 absence of the <var>soversion</var> in the package name.
5073 Files and support programs only useful when compiling software
5074 against the library should be included in the development
5075 package for the library.<footnote>
5076 For example, a <file><var>package-name</var>-config</file>
5077 script or <package>pkg-config</package> configuration files.
5082 <sect id="sharedlibs-static">
5083 <heading>Static libraries</heading>
5086 The static library (<file><var>libraryname.a</var></file>)
5087 is usually provided in addition to the shared version.
5088 It is placed into the development package (see below).
5092 In some cases, it is acceptable for a library to be
5093 available in static form only; these cases include:
5095 <item>libraries for languages whose shared library support
5096 is immature or unstable</item>
5097 <item>libraries whose interfaces are in flux or under
5098 development (commonly the case when the library's
5099 major version number is zero, or where the ABI breaks
5100 across patchlevels)</item>
5101 <item>libraries which are explicitly intended to be
5102 available only in static form by their upstream
5107 <sect id="sharedlibs-dev">
5108 <heading>Development files</heading>
5111 The development files associated to a shared library need to be
5112 placed in a package called
5113 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5114 or if you prefer only to support one development version at a
5115 time, <package><var>libraryname</var>-dev</package>.
5119 In case several development versions of a library exist, you may
5120 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5121 <ref id="conflicts">) to ensure that the user only installs one
5122 development version at a time (as different development versions are
5123 likely to have the same header files in them, which would cause a
5124 filename clash if both were installed).
5128 The development package should contain a symlink for the associated
5129 shared library without a version number. For example, the
5130 <package>libgdbm-dev</package> package should include a symlink
5131 from <file>/usr/lib/libgdbm.so</file> to
5132 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5133 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5134 <file>libgdbm.so</file> when compiling dynamically.
5138 <sect id="sharedlibs-intradeps">
5139 <heading>Dependencies between the packages of the same library</heading>
5142 Typically the development version should have an exact
5143 version dependency on the runtime library, to make sure that
5144 compilation and linking happens correctly. The
5145 <tt>${binary:Version}</tt> substitution variable can be
5146 useful for this purpose.
5148 Previously, <tt>${Source-Version}</tt> was used, but its name
5149 was confusing and it has been deprecated since dpkg 1.13.19.
5154 <sect id="sharedlibs-shlibdeps">
5155 <heading>Dependencies between the library and other packages -
5156 the <tt>shlibs</tt> system</heading>
5159 If a package contains a binary or library which links to a
5160 shared library, we must ensure that when the package is
5161 installed on the system, all of the libraries needed are
5162 also installed. This requirement led to the creation of the
5163 <tt>shlibs</tt> system, which is very simple in its design:
5164 any package which <em>provides</em> a shared library also
5165 provides information on the package dependencies required to
5166 ensure the presence of this library, and any package which
5167 <em>uses</em> a shared library uses this information to
5168 determine the dependencies it requires. The files which
5169 contain the mapping from shared libraries to the necessary
5170 dependency information are called <file>shlibs</file> files.
5174 Thus, when a package is built which contains any shared
5175 libraries, it must provide a <file>shlibs</file> file for other
5176 packages to use, and when a package is built which contains
5177 any shared libraries or compiled binaries, it must run
5178 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5179 on these to determine the libraries used and hence the
5180 dependencies needed by this package.<footnote>
5182 In the past, the shared libraries linked to were
5183 determined by calling <prgn>ldd</prgn>, but now
5184 <prgn>objdump</prgn> is used to do this. The only
5185 change this makes to package building is that
5186 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5187 libraries, whereas in the past this was unnecessary.
5188 The rest of this footnote explains the advantage that
5193 We say that a binary <tt>foo</tt> <em>directly</em> uses
5194 a library <tt>libbar</tt> if it is explicitly linked
5195 with that library (that is, it uses the flag
5196 <tt>-lbar</tt> during the linking stage). Other
5197 libraries that are needed by <tt>libbar</tt> are linked
5198 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5199 linker will load them automatically when it loads
5200 <tt>libbar</tt>. A package should depend on
5201 the libraries it directly uses, and the dependencies for
5202 those libraries should automatically pull in the other
5207 Unfortunately, the <prgn>ldd</prgn> program shows both
5208 the directly and indirectly used libraries, meaning that
5209 the dependencies determined included both direct and
5210 indirect dependencies. The use of <prgn>objdump</prgn>
5211 avoids this problem by determining only the directly
5216 A good example of where this helps is the following. We
5217 could update <tt>libimlib</tt> with a new version that
5218 supports a new graphics format called dgf (but retaining
5219 the same major version number). If we used the old
5220 <prgn>ldd</prgn> method, every package that uses
5221 <tt>libimlib</tt> would need to be recompiled so it
5222 would also depend on <tt>libdgf</tt> or it wouldn't run
5223 due to missing symbols. However with the new system,
5224 packages using <tt>libimlib</tt> can rely on
5225 <tt>libimlib</tt> itself having the dependency on
5226 <tt>libdgf</tt> and so they would not need rebuilding.
5232 In the following sections, we will first describe where the
5233 various <tt>shlibs</tt> files are to be found, then how to
5234 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5235 file format and how to create them if your package contains a
5240 <heading>The <tt>shlibs</tt> files present on the system</heading>
5243 There are several places where <tt>shlibs</tt> files are
5244 found. The following list gives them in the order in which
5246 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5247 (The first one which gives the required information is used.)
5253 <p><file>debian/shlibs.local</file></p>
5256 This lists overrides for this package. Its use is
5257 described below (see <ref id="shlibslocal">).
5262 <p><file>/etc/dpkg/shlibs.override</file></p>
5265 This lists global overrides. This list is normally
5266 empty. It is maintained by the local system
5272 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5275 When packages are being built, any
5276 <file>debian/shlibs</file> files are copied into the
5277 control file area of the temporary build directory and
5278 given the name <file>shlibs</file>. These files give
5279 details of any shared libraries included in the
5281 An example may help here. Let us say that the
5282 source package <tt>foo</tt> generates two binary
5283 packages, <tt>libfoo2</tt> and
5284 <tt>foo-runtime</tt>. When building the binary
5285 packages, the two packages are created in the
5286 directories <file>debian/libfoo2</file> and
5287 <file>debian/foo-runtime</file> respectively.
5288 (<file>debian/tmp</file> could be used instead of one
5289 of these.) Since <tt>libfoo2</tt> provides the
5290 <tt>libfoo</tt> shared library, it will require a
5291 <tt>shlibs</tt> file, which will be installed in
5292 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5294 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5295 when <prgn>dpkg-shlibdeps</prgn> is run on the
5297 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5299 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5300 determine whether <tt>foo-prog</tt>'s library
5301 dependencies are satisfied by any of the libraries
5302 provided by <tt>libfoo2</tt>. For this reason,
5303 <prgn>dpkg-shlibdeps</prgn> must only be run once
5304 all of the individual binary packages'
5305 <tt>shlibs</tt> files have been installed into the
5312 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5315 These are the <file>shlibs</file> files corresponding to
5316 all of the packages installed on the system, and are
5317 maintained by the relevant package maintainers.
5322 <p><file>/etc/dpkg/shlibs.default</file></p>
5325 This file lists any shared libraries whose packages
5326 have failed to provide correct <file>shlibs</file> files.
5327 It was used when the <file>shlibs</file> setup was first
5328 introduced, but it is now normally empty. It is
5329 maintained by the <tt>dpkg</tt> maintainer.
5337 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5338 <file>shlibs</file> files</heading>
5342 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5343 into your <file>debian/rules</file> file. If your package
5344 contains only compiled binaries and libraries (but no scripts),
5345 you can use a command such as:
5346 <example compact="compact">
5347 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5348 debian/tmp/usr/lib/*
5350 Otherwise, you will need to explicitly list the compiled
5351 binaries and libraries.<footnote>
5352 If you are using <tt>debhelper</tt>, the
5353 <prgn>dh_shlibdeps</prgn> program will do this work for
5354 you. It will also correctly handle multi-binary
5360 This command puts the dependency information into the
5361 <file>debian/substvars</file> file, which is then used by
5362 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5363 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5364 field in the control file for this to work.
5368 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5369 done. If it does complain you might need to create your own
5370 <file>debian/shlibs.local</file> file, as explained below (see
5371 <ref id="shlibslocal">).
5375 If you have multiple binary packages, you will need to call
5376 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5377 compiled libraries or binaries. In such a case, you will
5378 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5379 utilities to specify a different <file>substvars</file> file.
5383 If you are creating a udeb for use in the Debian Installer,
5384 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5385 should use the dependency line of type <tt>udeb</tt> by
5386 adding the <tt>-tudeb</tt> option<footnote>
5387 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5388 will automatically add this option if it knows it is
5390 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5391 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5392 fall back to the regular dependency line.
5396 For more details on dpkg-shlibdeps, please see
5397 <ref id="pkg-dpkg-shlibdeps"> and
5398 <manref name="dpkg-shlibdeps" section="1">.
5403 <heading>The <file>shlibs</file> File Format</heading>
5406 Each <file>shlibs</file> file has the same format. Lines
5407 beginning with <tt>#</tt> are considered to be comments and
5408 are ignored. Each line is of the form:
5409 <example compact="compact">
5410 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5415 We will explain this by reference to the example of the
5416 <tt>zlib1g</tt> package, which (at the time of writing)
5417 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5421 <var>type</var> is an optional element that indicates the type
5422 of package for which the line is valid. The only type currently
5423 in use is <tt>udeb</tt>. The colon and space after the type are
5428 <var>library-name</var> is the name of the shared library,
5429 in this case <tt>libz</tt>. (This must match the name part
5430 of the soname, see below.)
5434 <var>soname-version</var> is the version part of the soname of
5435 the library. The soname is the thing that must exactly match
5436 for the library to be recognized by the dynamic linker, and is
5438 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5439 example, <tt>libz.so.1</tt>.<footnote>
5440 This can be determined using the command
5441 <example compact="compact">
5442 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5445 The version part is the part which comes after
5446 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5450 <var>dependencies</var> has the same syntax as a dependency
5451 field in a binary package control file. It should give
5452 details of which packages are required to satisfy a binary
5453 built against the version of the library contained in the
5454 package. See <ref id="depsyntax"> for details.
5458 In our example, if the first version of the <tt>zlib1g</tt>
5459 package which contained a minor number of at least
5460 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5461 <tt>shlibs</tt> entry for this library could say:
5462 <example compact="compact">
5463 libz 1 zlib1g (>= 1:1.1.3)
5465 The version-specific dependency is to avoid warnings from
5466 the dynamic linker about using older shared libraries with
5471 As zlib1g also provides a udeb containing the shared library,
5472 there would also be a second line:
5473 <example compact="compact">
5474 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5480 <heading>Providing a <file>shlibs</file> file</heading>
5483 If your package provides a shared library, you need to create
5484 a <file>shlibs</file> file following the format described above.
5485 It is usual to call this file <file>debian/shlibs</file> (but if
5486 you have multiple binary packages, you might want to call it
5487 <file>debian/shlibs.<var>package</var></file> instead). Then
5488 let <file>debian/rules</file> install it in the control area:
5489 <example compact="compact">
5490 install -m644 debian/shlibs debian/tmp/DEBIAN
5492 or, in the case of a multi-binary package:
5493 <example compact="compact">
5494 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5496 An alternative way of doing this is to create the
5497 <file>shlibs</file> file in the control area directly from
5498 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5499 file at all,<footnote>
5500 This is what <prgn>dh_makeshlibs</prgn> in the
5501 <tt>debhelper</tt> suite does. If your package also has a udeb
5502 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5503 automatically generate the <tt>udeb:</tt> lines if you specify
5504 the name of the udeb with the <tt>--add-udeb</tt> option.
5506 since the <file>debian/shlibs</file> file itself is ignored by
5507 <prgn>dpkg-shlibdeps</prgn>.
5511 As <prgn>dpkg-shlibdeps</prgn> reads the
5512 <file>DEBIAN/shlibs</file> files in all of the binary packages
5513 being built from this source package, all of the
5514 <file>DEBIAN/shlibs</file> files should be installed before
5515 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5520 <sect1 id="shlibslocal">
5521 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5524 This file is intended only as a <em>temporary</em> fix if
5525 your binaries or libraries depend on a library whose package
5526 does not yet provide a correct <file>shlibs</file> file.
5530 We will assume that you are trying to package a binary
5531 <tt>foo</tt>. When you try running
5532 <prgn>dpkg-shlibdeps</prgn> you get the following error
5533 message (<tt>-O</tt> displays the dependency information on
5534 <tt>stdout</tt> instead of writing it to
5535 <tt>debian/substvars</tt>, and the lines have been wrapped
5536 for ease of reading):
5537 <example compact="compact">
5538 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5539 dpkg-shlibdeps: warning: unable to find dependency
5540 information for shared library libbar (soname 1,
5541 path /usr/lib/libbar.so.1, dependency field Depends)
5542 shlibs:Depends=libc6 (>= 2.2.2-2)
5544 You can then run <prgn>ldd</prgn> on the binary to find the
5545 full location of the library concerned:
5546 <example compact="compact">
5548 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5549 libc.so.6 => /lib/libc.so.6 (0x40032000)
5550 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5552 So the <prgn>foo</prgn> binary depends on the
5553 <prgn>libbar</prgn> shared library, but no package seems to
5554 provide a <file>*.shlibs</file> file handling
5555 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5556 determine the package responsible:
5557 <example compact="compact">
5558 $ dpkg -S /usr/lib/libbar.so.1
5559 bar1: /usr/lib/libbar.so.1
5560 $ dpkg -s bar1 | grep Version
5563 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5564 is the one we are using. Now we can file a bug against the
5565 <tt>bar1</tt> package and create our own
5566 <file>debian/shlibs.local</file> to locally fix the problem.
5567 Including the following line into your
5568 <file>debian/shlibs.local</file> file:
5569 <example compact="compact">
5570 libbar 1 bar1 (>= 1.0-1)
5572 should allow the package build to work.
5576 As soon as the maintainer of <tt>bar1</tt> provides a
5577 correct <file>shlibs</file> file, you should remove this line
5578 from your <file>debian/shlibs.local</file> file. (You should
5579 probably also then have a versioned <tt>Build-Depends</tt>
5580 on <tt>bar1</tt> to help ensure that others do not have the
5581 same problem building your package.)
5590 <chapt id="opersys"><heading>The Operating System</heading>
5593 <heading>File system hierarchy</heading>
5597 <heading>File System Structure</heading>
5600 The location of all installed files and directories must
5601 comply with the Filesystem Hierarchy Standard (FHS),
5602 version 2.3, with the exceptions noted below, and except
5603 where doing so would violate other terms of Debian
5604 Policy. The following exceptions to the FHS apply:
5609 The optional rules related to user specific
5610 configuration files for applications are stored in
5611 the user's home directory are relaxed. It is
5612 recommended that such files start with the
5613 '<tt>.</tt>' character (a "dot file"), and if an
5614 application needs to create more than one dot file
5615 then the preferred placement is in a subdirectory
5616 with a name starting with a '.' character, (a "dot
5617 directory"). In this case it is recommended the
5618 configuration files not start with the '.'
5624 The requirement for amd64 to use <file>/lib64</file>
5625 for 64 bit binaries is removed.
5630 The requirement for object files, internal binaries, and
5631 libraries, including <file>libc.so.*</file>, to be located
5632 directly under <file>/lib{,32}</file> and
5633 <file>/usr/lib{,32}</file> is amended, permitting files
5634 to instead be installed to
5635 <file>/lib/<var>triplet</var></file> and
5636 <file>/usr/lib/<var>triplet</var></file>, where
5637 <tt><var>triplet</var></tt> is the value returned by
5638 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5639 architecture of the package. Packages may <em>not</em>
5640 install files to any <var>triplet</var> path other
5641 than the one matching the architecture of that package;
5642 for instance, an <tt>Architecture: amd64</tt> package
5643 containing 32-bit x86 libraries may not install these
5644 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5646 This is necessary in order to reserve the directories for
5647 use in cross-installation of library packages from other
5648 architectures, as part of the planned deployment of
5653 Applications may also use a single subdirectory under
5654 <file>/usr/lib/<var>triplet</var></file>.
5657 The execution time linker/loader, ld*, must still be made
5658 available in the existing location under /lib or /lib64
5659 since this is part of the ELF ABI for the architecture.
5664 The requirement that
5665 <file>/usr/local/share/man</file> be "synonymous"
5666 with <file>/usr/local/man</file> is relaxed to a
5671 The requirement that windowmanagers with a single
5672 configuration file call it <file>system.*wmrc</file>
5673 is removed, as is the restriction that the window
5674 manager subdirectory be named identically to the
5675 window manager name itself.
5680 The requirement that boot manager configuration
5681 files live in <file>/etc</file>, or at least are
5682 symlinked there, is relaxed to a recommendation.
5687 The following directories in the root filesystem are
5688 additionally allowed: <file>/sys</file> and
5689 <file>/selinux</file>. <footnote>These directories
5690 are used as mount points to mount virtual filesystems
5691 to get access to kernel information.</footnote>
5698 The version of this document referred here can be
5699 found in the <tt>debian-policy</tt> package or on <url
5700 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5701 name="FHS (Debian copy)"> alongside this manual (or, if
5702 you have the <package>debian-policy</package> installed,
5704 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5705 (local copy)">). The
5706 latest version, which may be a more recent version, may
5708 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5709 Specific questions about following the standard may be
5710 asked on the <tt>debian-devel</tt> mailing list, or
5711 referred to the FHS mailing list (see the
5712 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5718 <heading>Site-specific programs</heading>
5721 As mandated by the FHS, packages must not place any
5722 files in <file>/usr/local</file>, either by putting them in
5723 the file system archive to be unpacked by <prgn>dpkg</prgn>
5724 or by manipulating them in their maintainer scripts.
5728 However, the package may create empty directories below
5729 <file>/usr/local</file> so that the system administrator knows
5730 where to place site-specific files. These are not
5731 directories <em>in</em> <file>/usr/local</file>, but are
5732 children of directories in <file>/usr/local</file>. These
5733 directories (<file>/usr/local/*/dir/</file>)
5734 should be removed on package removal if they are
5739 Note that this applies only to
5740 directories <em>below</em> <file>/usr/local</file>,
5741 not <em>in</em> <file>/usr/local</file>. Packages must
5742 not create sub-directories in the
5743 directory <file>/usr/local</file> itself, except those
5744 listed in FHS, section 4.5. However, you may create
5745 directories below them as you wish. You must not remove
5746 any of the directories listed in 4.5, even if you created
5751 Since <file>/usr/local</file> can be mounted read-only from a
5752 remote server, these directories must be created and
5753 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5754 maintainer scripts and not be included in the
5755 <file>.deb</file> archive. These scripts must not fail if
5756 either of these operations fail.
5760 For example, the <tt>emacsen-common</tt> package could
5761 contain something like
5762 <example compact="compact">
5763 if [ ! -e /usr/local/share/emacs ]
5765 if mkdir /usr/local/share/emacs 2>/dev/null
5767 chown root:staff /usr/local/share/emacs
5768 chmod 2775 /usr/local/share/emacs
5772 in its <prgn>postinst</prgn> script, and
5773 <example compact="compact">
5774 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5775 rmdir /usr/local/share/emacs 2>/dev/null || true
5777 in the <prgn>prerm</prgn> script. (Note that this form is
5778 used to ensure that if the script is interrupted, the
5779 directory <file>/usr/local/share/emacs</file> will still be
5784 If you do create a directory in <file>/usr/local</file> for
5785 local additions to a package, you should ensure that
5786 settings in <file>/usr/local</file> take precedence over the
5787 equivalents in <file>/usr</file>.
5791 However, because <file>/usr/local</file> and its contents are
5792 for exclusive use of the local administrator, a package
5793 must not rely on the presence or absence of files or
5794 directories in <file>/usr/local</file> for normal operation.
5798 The <file>/usr/local</file> directory itself and all the
5799 subdirectories created by the package should (by default) have
5800 permissions 2775 (group-writable and set-group-id) and be
5801 owned by <tt>root:staff</tt>.
5806 <heading>The system-wide mail directory</heading>
5808 The system-wide mail directory
5809 is <file>/var/mail</file>. This directory is part of the
5810 base system and should not be owned by any particular mail
5811 agents. The use of the old
5812 location <file>/var/spool/mail</file> is deprecated, even
5813 though the spool may still be physically located there.
5819 <heading>Users and groups</heading>
5822 <heading>Introduction</heading>
5824 The Debian system can be configured to use either plain or
5829 Some user ids (UIDs) and group ids (GIDs) are reserved
5830 globally for use by certain packages. Because some
5831 packages need to include files which are owned by these
5832 users or groups, or need the ids compiled into binaries,
5833 these ids must be used on any Debian system only for the
5834 purpose for which they are allocated. This is a serious
5835 restriction, and we should avoid getting in the way of
5836 local administration policies. In particular, many sites
5837 allocate users and/or local system groups starting at 100.
5841 Apart from this we should have dynamically allocated ids,
5842 which should by default be arranged in some sensible
5843 order, but the behavior should be configurable.
5847 Packages other than <tt>base-passwd</tt> must not modify
5848 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5849 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5854 <heading>UID and GID classes</heading>
5856 The UID and GID numbers are divided into classes as
5862 Globally allocated by the Debian project, the same
5863 on every Debian system. These ids will appear in
5864 the <file>passwd</file> and <file>group</file> files of all
5865 Debian systems, new ids in this range being added
5866 automatically as the <tt>base-passwd</tt> package is
5871 Packages which need a single statically allocated
5872 uid or gid should use one of these; their
5873 maintainers should ask the <tt>base-passwd</tt>
5881 Dynamically allocated system users and groups.
5882 Packages which need a user or group, but can have
5883 this user or group allocated dynamically and
5884 differently on each system, should use <tt>adduser
5885 --system</tt> to create the group and/or user.
5886 <prgn>adduser</prgn> will check for the existence of
5887 the user or group, and if necessary choose an unused
5888 id based on the ranges specified in
5889 <file>adduser.conf</file>.
5893 <tag>1000-29999:</tag>
5896 Dynamically allocated user accounts. By default
5897 <prgn>adduser</prgn> will choose UIDs and GIDs for
5898 user accounts in this range, though
5899 <file>adduser.conf</file> may be used to modify this
5904 <tag>30000-59999:</tag>
5909 <tag>60000-64999:</tag>
5912 Globally allocated by the Debian project, but only
5913 created on demand. The ids are allocated centrally
5914 and statically, but the actual accounts are only
5915 created on users' systems on demand.
5919 These ids are for packages which are obscure or
5920 which require many statically-allocated ids. These
5921 packages should check for and create the accounts in
5922 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5923 <prgn>adduser</prgn> if it has this facility) if
5924 necessary. Packages which are likely to require
5925 further allocations should have a "hole" left after
5926 them in the allocation, to give them room to
5931 <tag>65000-65533:</tag>
5939 User <tt>nobody</tt>. The corresponding gid refers
5940 to the group <tt>nogroup</tt>.
5947 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5948 not</em> be used, because it is the error return
5957 <sect id="sysvinit">
5958 <heading>System run levels and <file>init.d</file> scripts</heading>
5960 <sect1 id="/etc/init.d">
5961 <heading>Introduction</heading>
5964 The <file>/etc/init.d</file> directory contains the scripts
5965 executed by <prgn>init</prgn> at boot time and when the
5966 init state (or "runlevel") is changed (see <manref
5967 name="init" section="8">).
5971 There are at least two different, yet functionally
5972 equivalent, ways of handling these scripts. For the sake
5973 of simplicity, this document describes only the symbolic
5974 link method. However, it must not be assumed by maintainer
5975 scripts that this method is being used, and any automated
5976 manipulation of the various runlevel behaviors by
5977 maintainer scripts must be performed using
5978 <prgn>update-rc.d</prgn> as described below and not by
5979 manually installing or removing symlinks. For information
5980 on the implementation details of the other method,
5981 implemented in the <tt>file-rc</tt> package, please refer
5982 to the documentation of that package.
5986 These scripts are referenced by symbolic links in the
5987 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5988 runlevels, <prgn>init</prgn> looks in the directory
5989 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5990 execute, where <tt><var>n</var></tt> is the runlevel that
5991 is being changed to, or <tt>S</tt> for the boot-up
5996 The names of the links all have the form
5997 <file>S<var>mm</var><var>script</var></file> or
5998 <file>K<var>mm</var><var>script</var></file> where
5999 <var>mm</var> is a two-digit number and <var>script</var>
6000 is the name of the script (this should be the same as the
6001 name of the actual script in <file>/etc/init.d</file>).
6005 When <prgn>init</prgn> changes runlevel first the targets
6006 of the links whose names start with a <tt>K</tt> are
6007 executed, each with the single argument <tt>stop</tt>,
6008 followed by the scripts prefixed with an <tt>S</tt>, each
6009 with the single argument <tt>start</tt>. (The links are
6010 those in the <file>/etc/rc<var>n</var>.d</file> directory
6011 corresponding to the new runlevel.) The <tt>K</tt> links
6012 are responsible for killing services and the <tt>S</tt>
6013 link for starting services upon entering the runlevel.
6017 For example, if we are changing from runlevel 2 to
6018 runlevel 3, init will first execute all of the <tt>K</tt>
6019 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6020 all of the <tt>S</tt> prefixed scripts in that directory.
6021 The links starting with <tt>K</tt> will cause the
6022 referred-to file to be executed with an argument of
6023 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6028 The two-digit number <var>mm</var> is used to determine
6029 the order in which to run the scripts: low-numbered links
6030 have their scripts run first. For example, the
6031 <tt>K20</tt> scripts will be executed before the
6032 <tt>K30</tt> scripts. This is used when a certain service
6033 must be started before another. For example, the name
6034 server <prgn>bind</prgn> might need to be started before
6035 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6036 can set up its access lists. In this case, the script
6037 that starts <prgn>bind</prgn> would have a lower number
6038 than the script that starts <prgn>inn</prgn> so that it
6040 <example compact="compact">
6047 The two runlevels 0 (halt) and 6 (reboot) are slightly
6048 different. In these runlevels, the links with an
6049 <tt>S</tt> prefix are still called after those with a
6050 <tt>K</tt> prefix, but they too are called with the single
6051 argument <tt>stop</tt>.
6056 <heading>Writing the scripts</heading>
6059 Packages that include daemons for system services should
6060 place scripts in <file>/etc/init.d</file> to start or stop
6061 services at boot time or during a change of runlevel.
6062 These scripts should be named
6063 <file>/etc/init.d/<var>package</var></file>, and they should
6064 accept one argument, saying what to do:
6067 <tag><tt>start</tt></tag>
6068 <item>start the service,</item>
6070 <tag><tt>stop</tt></tag>
6071 <item>stop the service,</item>
6073 <tag><tt>restart</tt></tag>
6074 <item>stop and restart the service if it's already running,
6075 otherwise start the service</item>
6077 <tag><tt>reload</tt></tag>
6078 <item><p>cause the configuration of the service to be
6079 reloaded without actually stopping and restarting
6082 <tag><tt>force-reload</tt></tag>
6083 <item>cause the configuration to be reloaded if the
6084 service supports this, otherwise restart the
6088 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6089 <tt>force-reload</tt> options should be supported by all
6090 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6095 The <file>init.d</file> scripts must ensure that they will
6096 behave sensibly (i.e., returning success and not starting
6097 multiple copies of a service) if invoked with <tt>start</tt>
6098 when the service is already running, or with <tt>stop</tt>
6099 when it isn't, and that they don't kill unfortunately-named
6100 user processes. The best way to achieve this is usually to
6101 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6106 If a service reloads its configuration automatically (as
6107 in the case of <prgn>cron</prgn>, for example), the
6108 <tt>reload</tt> option of the <file>init.d</file> script
6109 should behave as if the configuration has been reloaded
6114 The <file>/etc/init.d</file> scripts must be treated as
6115 configuration files, either (if they are present in the
6116 package, that is, in the .deb file) by marking them as
6117 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6118 by managing them correctly in the maintainer scripts (see
6119 <ref id="config-files">). This is important since we want
6120 to give the local system administrator the chance to adapt
6121 the scripts to the local system, e.g., to disable a
6122 service without de-installing the package, or to specify
6123 some special command line options when starting a service,
6124 while making sure their changes aren't lost during the next
6129 These scripts should not fail obscurely when the
6130 configuration files remain but the package has been
6131 removed, as configuration files remain on the system after
6132 the package has been removed. Only when <prgn>dpkg</prgn>
6133 is executed with the <tt>--purge</tt> option will
6134 configuration files be removed. In particular, as the
6135 <file>/etc/init.d/<var>package</var></file> script itself is
6136 usually a <tt>conffile</tt>, it will remain on the system
6137 if the package is removed but not purged. Therefore, you
6138 should include a <tt>test</tt> statement at the top of the
6140 <example compact="compact">
6141 test -f <var>program-executed-later-in-script</var> || exit 0
6146 Often there are some variables in the <file>init.d</file>
6147 scripts whose values control the behavior of the scripts,
6148 and which a system administrator is likely to want to
6149 change. As the scripts themselves are frequently
6150 <tt>conffile</tt>s, modifying them requires that the
6151 administrator merge in their changes each time the package
6152 is upgraded and the <tt>conffile</tt> changes. To ease
6153 the burden on the system administrator, such configurable
6154 values should not be placed directly in the script.
6155 Instead, they should be placed in a file in
6156 <file>/etc/default</file>, which typically will have the same
6157 base name as the <file>init.d</file> script. This extra file
6158 should be sourced by the script when the script runs. It
6159 must contain only variable settings and comments in SUSv3
6160 <prgn>sh</prgn> format. It may either be a
6161 <tt>conffile</tt> or a configuration file maintained by
6162 the package maintainer scripts. See <ref id="config-files">
6167 To ensure that vital configurable values are always
6168 available, the <file>init.d</file> script should set default
6169 values for each of the shell variables it uses, either
6170 before sourcing the <file>/etc/default/</file> file or
6171 afterwards using something like the <tt>:
6172 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6173 script must behave sensibly and not fail if the
6174 <file>/etc/default</file> file is deleted.
6178 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6179 as temporary filesystems<footnote>
6180 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6181 options in <file>/etc/default/rcS</file>.
6182 </footnote>, so the <file>init.d</file> scripts must handle this
6183 correctly. This will typically amount to creating any required
6184 subdirectories dynamically when the <file>init.d</file> script
6185 is run, rather than including them in the package and relying on
6186 <prgn>dpkg</prgn> to create them.
6191 <heading>Interfacing with the initscript system</heading>
6194 Maintainers should use the abstraction layer provided by
6195 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6196 programs to deal with initscripts in their packages'
6197 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6198 and <prgn>postrm</prgn>.
6202 Directly managing the /etc/rc?.d links and directly
6203 invoking the <file>/etc/init.d/</file> initscripts should
6204 be done only by packages providing the initscript
6205 subsystem (such as <prgn>sysv-rc</prgn> and
6206 <prgn>file-rc</prgn>).
6210 <heading>Managing the links</heading>
6213 The program <prgn>update-rc.d</prgn> is provided for
6214 package maintainers to arrange for the proper creation and
6215 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6216 or their functional equivalent if another method is being
6217 used. This may be used by maintainers in their packages'
6218 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6222 You must not include any <file>/etc/rc<var>n</var>.d</file>
6223 symbolic links in the actual archive or manually create or
6224 remove the symbolic links in maintainer scripts; you must
6225 use the <prgn>update-rc.d</prgn> program instead. (The
6226 former will fail if an alternative method of maintaining
6227 runlevel information is being used.) You must not include
6228 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6229 in the archive either. (Only the <tt>sysvinit</tt>
6234 By default <prgn>update-rc.d</prgn> will start services in
6235 each of the multi-user state runlevels (2, 3, 4, and 5)
6236 and stop them in the halt runlevel (0), the single-user
6237 runlevel (1) and the reboot runlevel (6). The system
6238 administrator will have the opportunity to customize
6239 runlevels by simply adding, moving, or removing the
6240 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6241 symbolic links are being used, or by modifying
6242 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6247 To get the default behavior for your package, put in your
6248 <prgn>postinst</prgn> script
6249 <example compact="compact">
6250 update-rc.d <var>package</var> defaults
6252 and in your <prgn>postrm</prgn>
6253 <example compact="compact">
6254 if [ "$1" = purge ]; then
6255 update-rc.d <var>package</var> remove
6257 </example>. Note that if your package changes runlevels
6258 or priority, you may have to remove and recreate the links,
6259 since otherwise the old links may persist. Refer to the
6260 documentation of <prgn>update-rc.d</prgn>.
6264 This will use a default sequence number of 20. If it does
6265 not matter when or in which order the <file>init.d</file>
6266 script is run, use this default. If it does, then you
6267 should talk to the maintainer of the <prgn>sysvinit</prgn>
6268 package or post to <tt>debian-devel</tt>, and they will
6269 help you choose a number.
6273 For more information about using <tt>update-rc.d</tt>,
6274 please consult its man page <manref name="update-rc.d"
6280 <heading>Running initscripts</heading>
6282 The program <prgn>invoke-rc.d</prgn> is provided to make
6283 it easier for package maintainers to properly invoke an
6284 initscript, obeying runlevel and other locally-defined
6285 constraints that might limit a package's right to start,
6286 stop and otherwise manage services. This program may be
6287 used by maintainers in their packages' scripts.
6291 The package maintainer scripts must use
6292 <prgn>invoke-rc.d</prgn> to invoke the
6293 <file>/etc/init.d/*</file> initscripts, instead of
6294 calling them directly.
6298 By default, <prgn>invoke-rc.d</prgn> will pass any
6299 action requests (start, stop, reload, restart...) to the
6300 <file>/etc/init.d</file> script, filtering out requests
6301 to start or restart a service out of its intended
6306 Most packages will simply need to change:
6307 <example compact="compact">/etc/init.d/<package>
6308 <action></example> in their <prgn>postinst</prgn>
6309 and <prgn>prerm</prgn> scripts to:
6310 <example compact="compact">
6311 if which invoke-rc.d >/dev/null 2>&1; then
6312 invoke-rc.d <var>package</var> <action>
6314 /etc/init.d/<var>package</var> <action>
6320 A package should register its initscript services using
6321 <prgn>update-rc.d</prgn> before it tries to invoke them
6322 using <prgn>invoke-rc.d</prgn>. Invocation of
6323 unregistered services may fail.
6327 For more information about using
6328 <prgn>invoke-rc.d</prgn>, please consult its man page
6329 <manref name="invoke-rc.d" section="8">.
6335 <heading>Boot-time initialization</heading>
6338 There used to be another directory, <file>/etc/rc.boot</file>,
6339 which contained scripts which were run once per machine
6340 boot. This has been deprecated in favour of links from
6341 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6342 described in <ref id="/etc/init.d">. Packages must not
6343 place files in <file>/etc/rc.boot</file>.
6348 <heading>Example</heading>
6351 An example on which you can base your
6352 <file>/etc/init.d</file> scripts is found in
6353 <file>/etc/init.d/skeleton</file>.
6360 <heading>Console messages from <file>init.d</file> scripts</heading>
6363 This section describes the formats to be used for messages
6364 written to standard output by the <file>/etc/init.d</file>
6365 scripts. The intent is to improve the consistency of
6366 Debian's startup and shutdown look and feel. For this
6367 reason, please look very carefully at the details. We want
6368 the messages to have the same format in terms of wording,
6369 spaces, punctuation and case of letters.
6373 Here is a list of overall rules that should be used for
6374 messages generated by <file>/etc/init.d</file> scripts.
6380 The message should fit in one line (fewer than 80
6381 characters), start with a capital letter and end with
6382 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6386 If the script is performing some time consuming task in
6387 the background (not merely starting or stopping a
6388 program, for instance), an ellipsis (three dots:
6389 <tt>...</tt>) should be output to the screen, with no
6390 leading or tailing whitespace or line feeds.
6394 The messages should appear as if the computer is telling
6395 the user what it is doing (politely :-), but should not
6396 mention "it" directly. For example, instead of:
6397 <example compact="compact">
6398 I'm starting network daemons: nfsd mountd.
6400 the message should say
6401 <example compact="compact">
6402 Starting network daemons: nfsd mountd.
6409 <tt>init.d</tt> script should use the following standard
6410 message formats for the situations enumerated below.
6416 <p>When daemons are started</p>
6419 If the script starts one or more daemons, the output
6420 should look like this (a single line, no leading
6422 <example compact="compact">
6423 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6425 The <var>description</var> should describe the
6426 subsystem the daemon or set of daemons are part of,
6427 while <var>daemon-1</var> up to <var>daemon-n</var>
6428 denote each daemon's name (typically the file name of
6433 For example, the output of <file>/etc/init.d/lpd</file>
6435 <example compact="compact">
6436 Starting printer spooler: lpd.
6441 This can be achieved by saying
6442 <example compact="compact">
6443 echo -n "Starting printer spooler: lpd"
6444 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6447 in the script. If there are more than one daemon to
6448 start, the output should look like this:
6449 <example compact="compact">
6450 echo -n "Starting remote file system services:"
6451 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6452 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6453 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6456 This makes it possible for the user to see what is
6457 happening and when the final daemon has been started.
6458 Care should be taken in the placement of white spaces:
6459 in the example above the system administrators can
6460 easily comment out a line if they don't want to start
6461 a specific daemon, while the displayed message still
6467 <p>When a system parameter is being set</p>
6470 If you have to set up different system parameters
6471 during the system boot, you should use this format:
6472 <example compact="compact">
6473 Setting <var>parameter</var> to "<var>value</var>".
6478 You can use a statement such as the following to get
6480 <example compact="compact">
6481 echo "Setting DNS domainname to \"$domainname\"."
6486 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6487 for the left and right quotation marks. A grave accent
6488 (<tt>`</tt>) is not a quote character; neither is an
6489 apostrophe (<tt>'</tt>).
6494 <p>When a daemon is stopped or restarted</p>
6497 When you stop or restart a daemon, you should issue a
6498 message identical to the startup message, except that
6499 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6500 or <tt>Restarting</tt> respectively.
6504 For example, stopping the printer daemon will look like
6506 <example compact="compact">
6507 Stopping printer spooler: lpd.
6513 <p>When something is executed</p>
6516 There are several examples where you have to run a
6517 program at system startup or shutdown to perform a
6518 specific task, for example, setting the system's clock
6519 using <prgn>netdate</prgn> or killing all processes
6520 when the system shuts down. Your message should look
6522 <example compact="compact">
6523 Doing something very useful...done.
6525 You should print the <tt>done.</tt> immediately after
6526 the job has been completed, so that the user is
6527 informed why they have to wait. You can get this
6529 <example compact="compact">
6530 echo -n "Doing something very useful..."
6539 <p>When the configuration is reloaded</p>
6542 When a daemon is forced to reload its configuration
6543 files you should use the following format:
6544 <example compact="compact">
6545 Reloading <var>description</var> configuration...done.
6547 where <var>description</var> is the same as in the
6548 daemon starting message.
6556 <heading>Cron jobs</heading>
6559 Packages must not modify the configuration file
6560 <file>/etc/crontab</file>, and they must not modify the files in
6561 <file>/var/spool/cron/crontabs</file>.</p>
6564 If a package wants to install a job that has to be executed
6565 via cron, it should place a file with the name of the
6566 package in one or more of the following directories:
6567 <example compact="compact">
6573 As these directory names imply, the files within them are
6574 executed on an hourly, daily, weekly, or monthly basis,
6575 respectively. The exact times are listed in
6576 <file>/etc/crontab</file>.</p>
6579 All files installed in any of these directories must be
6580 scripts (e.g., shell scripts or Perl scripts) so that they
6581 can easily be modified by the local system administrator.
6582 In addition, they must be treated as configuration files.
6586 If a certain job has to be executed at some other frequency or
6587 at a specific time, the package should install a file
6588 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6589 same syntax as <file>/etc/crontab</file> and is processed by
6590 <prgn>cron</prgn> automatically. The file must also be
6591 treated as a configuration file. (Note that entries in the
6592 <file>/etc/cron.d</file> directory are not handled by
6593 <prgn>anacron</prgn>. Thus, you should only use this
6594 directory for jobs which may be skipped if the system is not
6597 Unlike <file>crontab</file> files described in the IEEE Std
6598 1003.1-2008 (POSIX.1) available from
6599 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6600 name="The Open Group">, the files in
6601 <file>/etc/cron.d</file> and the file
6602 <file>/etc/crontab</file> have seven fields; namely:
6604 <item>Minute [0,59]</item>
6605 <item>Hour [0,23]</item>
6606 <item>Day of the month [1,31]</item>
6607 <item>Month of the year [1,12]</item>
6608 <item>Day of the week ([0,6] with 0=Sunday)</item>
6609 <item>Username</item>
6610 <item>Command to be run</item>
6612 Ranges of numbers are allowed. Ranges are two numbers
6613 separated with a hyphen. The specified range is inclusive.
6614 Lists are allowed. A list is a set of numbers (or ranges)
6615 separated by commas. Step values can be used in conjunction
6620 The scripts or <tt>crontab</tt> entries in these directories should
6621 check if all necessary programs are installed before they
6622 try to execute them. Otherwise, problems will arise when a
6623 package was removed but not purged since configuration files
6624 are kept on the system in this situation.
6628 Any <tt>cron</tt> daemon must provide
6629 <file>/usr/bin/crontab</file> and support normal
6630 <tt>crontab</tt> entries as specified in POSIX. The daemon
6631 must also support names for days and months, ranges, and
6632 step values. It has to support <file>/etc/crontab</file>,
6633 and correctly execute the scripts in
6634 <file>/etc/cron.d</file>. The daemon must also correctly
6636 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6641 <heading>Menus</heading>
6644 The Debian <tt>menu</tt> package provides a standard
6645 interface between packages providing applications and
6646 <em>menu programs</em> (either X window managers or
6647 text-based menu programs such as <prgn>pdmenu</prgn>).
6651 All packages that provide applications that need not be
6652 passed any special command line arguments for normal
6653 operation should register a menu entry for those
6654 applications, so that users of the <tt>menu</tt> package
6655 will automatically get menu entries in their window
6656 managers, as well in shells like <tt>pdmenu</tt>.
6660 Menu entries should follow the current menu policy.
6664 The menu policy can be found in the <tt>menu-policy</tt>
6665 files in the <tt>debian-policy</tt> package.
6666 It is also available from the Debian web mirrors at
6667 <tt><url name="/doc/packaging-manuals/menu-policy/"
6668 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6672 Please also refer to the <em>Debian Menu System</em>
6673 documentation that comes with the <package>menu</package>
6674 package for information about how to register your
6680 <heading>Multimedia handlers</heading>
6683 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6684 is a mechanism for encoding files and data streams and
6685 providing meta-information about them, in particular their
6686 type (e.g. audio or video) and format (e.g. PNG, HTML,
6691 Registration of MIME type handlers allows programs like mail
6692 user agents and web browsers to invoke these handlers to
6693 view, edit or display MIME types they don't support directly.
6697 Packages which provide the ability to view/show/play,
6698 compose, edit or print MIME types should register themselves
6699 as such following the current MIME support policy.
6703 The MIME support policy can be found in the <tt>mime-policy</tt>
6704 files in the <tt>debian-policy</tt> package.
6705 It is also available from the Debian web mirrors at
6706 <tt><url name="/doc/packaging-manuals/mime-policy/"
6707 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6713 <heading>Keyboard configuration</heading>
6716 To achieve a consistent keyboard configuration so that all
6717 applications interpret a keyboard event the same way, all
6718 programs in the Debian distribution must be configured to
6719 comply with the following guidelines.
6723 The following keys must have the specified interpretations:
6726 <tag><tt><--</tt></tag>
6727 <item>delete the character to the left of the cursor</item>
6729 <tag><tt>Delete</tt></tag>
6730 <item>delete the character to the right of the cursor</item>
6732 <tag><tt>Control+H</tt></tag>
6733 <item>emacs: the help prefix</item>
6736 The interpretation of any keyboard events should be
6737 independent of the terminal that is used, be it a virtual
6738 console, an X terminal emulator, an rlogin/telnet session,
6743 The following list explains how the different programs
6744 should be set up to achieve this:
6750 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6754 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6758 X translations are set up to make
6759 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6760 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6761 is the vt220 escape code for the "delete character"
6762 key). This must be done by loading the X resources
6763 using <prgn>xrdb</prgn> on all local X displays, not
6764 using the application defaults, so that the
6765 translation resources used correspond to the
6766 <prgn>xmodmap</prgn> settings.
6770 The Linux console is configured to make
6771 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6772 generate <tt>ESC [ 3 ~</tt>.
6776 X applications are configured so that <tt><</tt>
6777 deletes left, and <tt>Delete</tt> deletes right. Motif
6778 applications already work like this.
6782 Terminals should have <tt>stty erase ^?</tt> .
6786 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6787 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6788 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6792 Emacs is programmed to map <tt>KB_Backspace</tt> or
6793 the <tt>stty erase</tt> character to
6794 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6795 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6796 <tt>^H</tt> to <tt>help</tt> as always.
6800 Other applications use the <tt>stty erase</tt>
6801 character and <tt>kdch1</tt> for the two delete keys,
6802 with ASCII DEL being "delete previous character" and
6803 <tt>kdch1</tt> being "delete character under
6811 This will solve the problem except for the following
6818 Some terminals have a <tt><--</tt> key that cannot
6819 be made to produce anything except <tt>^H</tt>. On
6820 these terminals Emacs help will be unavailable on
6821 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6822 character takes precedence in Emacs, and has been set
6823 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6824 available) can be used instead.
6828 Some operating systems use <tt>^H</tt> for <tt>stty
6829 erase</tt>. However, modern telnet versions and all
6830 rlogin versions propagate <tt>stty</tt> settings, and
6831 almost all UNIX versions honour <tt>stty erase</tt>.
6832 Where the <tt>stty</tt> settings are not propagated
6833 correctly, things can be made to work by using
6834 <tt>stty</tt> manually.
6838 Some systems (including previous Debian versions) use
6839 <prgn>xmodmap</prgn> to arrange for both
6840 <tt><--</tt> and <tt>Delete</tt> to generate
6841 <tt>KB_Delete</tt>. We can change the behavior of
6842 their X clients using the same X resources that we use
6843 to do it for our own clients, or configure our clients
6844 using their resources when things are the other way
6845 around. On displays configured like this
6846 <tt>Delete</tt> will not work, but <tt><--</tt>
6851 Some operating systems have different <tt>kdch1</tt>
6852 settings in their <tt>terminfo</tt> database for
6853 <tt>xterm</tt> and others. On these systems the
6854 <tt>Delete</tt> key will not work correctly when you
6855 log in from a system conforming to our policy, but
6856 <tt><--</tt> will.
6863 <heading>Environment variables</heading>
6866 A program must not depend on environment variables to get
6867 reasonable defaults. (That's because these environment
6868 variables would have to be set in a system-wide
6869 configuration file like <file>/etc/profile</file>, which is not
6870 supported by all shells.)
6874 If a program usually depends on environment variables for its
6875 configuration, the program should be changed to fall back to
6876 a reasonable default configuration if these environment
6877 variables are not present. If this cannot be done easily
6878 (e.g., if the source code of a non-free program is not
6879 available), the program must be replaced by a small
6880 "wrapper" shell script which sets the environment variables
6881 if they are not already defined, and calls the original program.
6885 Here is an example of a wrapper script for this purpose:
6887 <example compact="compact">
6889 BAR=${BAR:-/var/lib/fubar}
6891 exec /usr/lib/foo/foo "$@"
6896 Furthermore, as <file>/etc/profile</file> is a configuration
6897 file of the <prgn>base-files</prgn> package, other packages must
6898 not put any environment variables or other commands into that
6903 <sect id="doc-base">
6904 <heading>Registering Documents using doc-base</heading>
6907 The <package>doc-base</package> package implements a
6908 flexible mechanism for handling and presenting
6909 documentation. The recommended practice is for every Debian
6910 package that provides online documentation (other than just
6911 manual pages) to register these documents with
6912 <package>doc-base</package> by installing a
6913 <package>doc-base</package> control file via the
6914 <prgn/install-docs/ script at installation time and
6915 de-register the manuals again when the package is removed.
6918 Please refer to the documentation that comes with the
6919 <package>doc-base</package> package for information and
6928 <heading>Files</heading>
6931 <heading>Binaries</heading>
6934 Two different packages must not install programs with
6935 different functionality but with the same filenames. (The
6936 case of two programs having the same functionality but
6937 different implementations is handled via "alternatives" or
6938 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6939 <ref id="conflicts"> respectively.) If this case happens,
6940 one of the programs must be renamed. The maintainers should
6941 report this to the <tt>debian-devel</tt> mailing list and
6942 try to find a consensus about which program will have to be
6943 renamed. If a consensus cannot be reached, <em>both</em>
6944 programs must be renamed.
6948 By default, when a package is being built, any binaries
6949 created should include debugging information, as well as
6950 being compiled with optimization. You should also turn on
6951 as many reasonable compilation warnings as possible; this
6952 makes life easier for porters, who can then look at build
6953 logs for possible problems. For the C programming language,
6954 this means the following compilation parameters should be
6956 <example compact="compact">
6958 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6960 INSTALL = install -s # (or use strip on the files in debian/tmp)
6965 Note that by default all installed binaries should be stripped,
6966 either by using the <tt>-s</tt> flag to
6967 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6968 the binaries after they have been copied into
6969 <file>debian/tmp</file> but before the tree is made into a
6974 Although binaries in the build tree should be compiled with
6975 debugging information by default, it can often be difficult to
6976 debug programs if they are also subjected to compiler
6977 optimization. For this reason, it is recommended to support the
6978 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6979 (see <ref id="debianrules-options">). This variable can contain
6980 several flags to change how a package is compiled and built.
6984 It is up to the package maintainer to decide what
6985 compilation options are best for the package. Certain
6986 binaries (such as computationally-intensive programs) will
6987 function better with certain flags (<tt>-O3</tt>, for
6988 example); feel free to use them. Please use good judgment
6989 here. Don't use flags for the sake of it; only use them
6990 if there is good reason to do so. Feel free to override
6991 the upstream author's ideas about which compilation
6992 options are best: they are often inappropriate for our
6998 <sect id="libraries">
6999 <heading>Libraries</heading>
7002 If the package is <strong>architecture: any</strong>, then
7003 the shared library compilation and linking flags must have
7004 <tt>-fPIC</tt>, or the package shall not build on some of
7005 the supported architectures<footnote>
7007 If you are using GCC, <tt>-fPIC</tt> produces code with
7008 relocatable position independent code, which is required for
7009 most architectures to create a shared library, with i386 and
7010 perhaps some others where non position independent code is
7011 permitted in a shared library.
7014 Position independent code may have a performance penalty,
7015 especially on <tt>i386</tt>. However, in most cases the
7016 speed penalty must be measured against the memory wasted on
7017 the few architectures where non position independent code is
7020 </footnote>. Any exception to this rule must be discussed on
7021 the mailing list <em>debian-devel@lists.debian.org</em>, and
7022 a rough consensus obtained. The reasons for not compiling
7023 with <tt>-fPIC</tt> flag must be recorded in the file
7024 <tt>README.Debian</tt>, and care must be taken to either
7025 restrict the architecture or arrange for <tt>-fPIC</tt> to
7026 be used on architectures where it is required.<footnote>
7028 Some of the reasons why this might be required is if the
7029 library contains hand crafted assembly code that is not
7030 relocatable, the speed penalty is excessive for compute
7031 intensive libs, and similar reasons.
7036 As to the static libraries, the common case is not to have
7037 relocatable code, since there is no benefit, unless in specific
7038 cases; therefore the static version must not be compiled
7039 with the <tt>-fPIC</tt> flag. Any exception to this rule
7040 should be discussed on the mailing list
7041 <em>debian-devel@lists.debian.org</em>, and the reasons for
7042 compiling with the <tt>-fPIC</tt> flag must be recorded in
7043 the file <tt>README.Debian</tt>. <footnote>
7045 Some of the reasons for linking static libraries with
7046 the <tt>-fPIC</tt> flag are if, for example, one needs a
7047 Perl API for a library that is under rapid development,
7048 and has an unstable API, so shared libraries are
7049 pointless at this phase of the library's development. In
7050 that case, since Perl needs a library with relocatable
7051 code, it may make sense to create a static library with
7052 relocatable code. Another reason cited is if you are
7053 distilling various libraries into a common shared
7054 library, like <tt>mklibs</tt> does in the Debian
7060 In other words, if both a shared and a static library is
7061 being built, each source unit (<tt>*.c</tt>, for example,
7062 for C files) will need to be compiled twice, for the normal
7066 You must specify the gcc option <tt>-D_REENTRANT</tt>
7067 when building a library (either static or shared) to make
7068 the library compatible with LinuxThreads.
7072 Although not enforced by the build tools, shared libraries
7073 must be linked against all libraries that they use symbols from
7074 in the same way that binaries are. This ensures the correct
7075 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7076 system and guarantees that all libraries can be safely opened
7077 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7078 option <tt>-Wl,-z,defs</tt> when building a shared library.
7079 Since this option enforces symbol resolution at build time,
7080 a missing library reference will be caught early as a fatal
7085 All installed shared libraries should be stripped with
7086 <example compact="compact">
7087 strip --strip-unneeded <var>your-lib</var>
7089 (The option <tt>--strip-unneeded</tt> makes
7090 <prgn>strip</prgn> remove only the symbols which aren't
7091 needed for relocation processing.) Shared libraries can
7092 function perfectly well when stripped, since the symbols for
7093 dynamic linking are in a separate part of the ELF object
7095 You might also want to use the options
7096 <tt>--remove-section=.comment</tt> and
7097 <tt>--remove-section=.note</tt> on both shared libraries
7098 and executables, and <tt>--strip-debug</tt> on static
7104 Note that under some circumstances it may be useful to
7105 install a shared library unstripped, for example when
7106 building a separate package to support debugging.
7110 Shared object files (often <file>.so</file> files) that are not
7111 public libraries, that is, they are not meant to be linked
7112 to by third party executables (binaries of other packages),
7113 should be installed in subdirectories of the
7114 <file>/usr/lib</file> directory. Such files are exempt from the
7115 rules that govern ordinary shared libraries, except that
7116 they must not be installed executable and should be
7118 A common example are the so-called "plug-ins",
7119 internal shared objects that are dynamically loaded by
7120 programs using <manref name="dlopen" section="3">.
7125 An ever increasing number of packages are using
7126 <prgn>libtool</prgn> to do their linking. The latest GNU
7127 libtools (>= 1.3a) can take advantage of the metadata in the
7128 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7129 files). The main advantage of <prgn>libtool</prgn>'s
7130 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7131 store and subsequently access metadata with respect to the
7132 libraries it builds. <prgn>libtool</prgn> will search for
7133 those files, which contain a lot of useful information about
7134 a library (such as library dependency information for static
7135 linking). Also, they're <em>essential</em> for programs
7136 using <tt>libltdl</tt>.<footnote>
7137 Although <prgn>libtool</prgn> is fully capable of
7138 linking against shared libraries which don't have
7139 <tt>.la</tt> files, as it is a mere shell script it can
7140 add considerably to the build time of a
7141 <prgn>libtool</prgn>-using package if that shell script
7142 has to derive all this information from first principles
7143 for each library every time it is linked. With the
7144 advent of <prgn>libtool</prgn> version 1.4 (and to a
7145 lesser extent <prgn>libtool</prgn> version 1.3), the
7146 <file>.la</file> files also store information about
7147 inter-library dependencies which cannot necessarily be
7148 derived after the <file>.la</file> file is deleted.
7153 Packages that use <prgn>libtool</prgn> to create shared
7154 libraries should include the <file>.la</file> files in the
7155 <tt>-dev</tt> package, unless the package relies on
7156 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7157 the <tt>.la</tt> files must go in the run-time library
7162 You must make sure that you use only released versions of
7163 shared libraries to build your packages; otherwise other
7164 users will not be able to run your binaries
7165 properly. Producing source packages that depend on
7166 unreleased compilers is also usually a bad
7173 <heading>Shared libraries</heading>
7175 This section has moved to <ref id="sharedlibs">.
7181 <heading>Scripts</heading>
7184 All command scripts, including the package maintainer
7185 scripts inside the package and used by <prgn>dpkg</prgn>,
7186 should have a <tt>#!</tt> line naming the shell to be used
7191 In the case of Perl scripts this should be
7192 <tt>#!/usr/bin/perl</tt>.
7196 When scripts are installed into a directory in the system
7197 PATH, the script name should not include an extension such
7198 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7199 language currently used to implement it.
7202 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7203 should almost certainly start with <tt>set -e</tt> so that
7204 errors are detected. Every script should use
7205 <tt>set -e</tt> or check the exit status of <em>every</em>
7210 Scripts may assume that <file>/bin/sh</file> implements the
7211 SUSv3 Shell Command Language<footnote>
7212 Single UNIX Specification, version 3, which is also IEEE
7213 1003.1-2004 (POSIX), and is available on the World Wide Web
7214 from <url id="http://www.unix.org/version3/online.html"
7215 name="The Open Group"> after free
7216 registration.</footnote>
7217 plus the following additional features not mandated by
7219 These features are in widespread use in the Linux community
7220 and are implemented in all of bash, dash, and ksh, the most
7221 common shells users may wish to use as <file>/bin/sh</file>.
7224 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7225 must not generate a newline.</item>
7226 <item><tt>test</tt>, if implemented as a shell built-in, must
7227 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7229 <item><tt>local</tt> to create a scoped variable must be
7230 supported, including listing multiple variables in a single
7231 local command and assigning a value to a variable at the
7232 same time as localizing it. <tt>local</tt> may or
7233 may not preserve the variable value from an outer scope if
7234 no assignment is present. Uses such as:
7238 # ... use a, b, c, d ...
7241 must be supported and must set the value of <tt>c</tt> to
7245 If a shell script requires non-SUSv3 features from the shell
7246 interpreter other than those listed above, the appropriate shell
7247 must be specified in the first line of the script (e.g.,
7248 <tt>#!/bin/bash</tt>) and the package must depend on the package
7249 providing the shell (unless the shell package is marked
7250 "Essential", as in the case of <prgn>bash</prgn>).
7254 You may wish to restrict your script to SUSv3 features plus the
7255 above set when possible so that it may use <file>/bin/sh</file>
7256 as its interpreter. If your script works with <prgn>dash</prgn>
7257 (originally called <prgn>ash</prgn>), it probably complies with
7258 the above requirements, but if you are in doubt, use
7259 <file>/bin/bash</file>.
7263 Perl scripts should check for errors when making any
7264 system calls, including <tt>open</tt>, <tt>print</tt>,
7265 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7269 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7270 scripting languages. See <em>Csh Programming Considered
7271 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7272 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7273 If an upstream package comes with <prgn>csh</prgn> scripts
7274 then you must make sure that they start with
7275 <tt>#!/bin/csh</tt> and make your package depend on the
7276 <prgn>c-shell</prgn> virtual package.
7280 Any scripts which create files in world-writeable
7281 directories (e.g., in <file>/tmp</file>) must use a
7282 mechanism which will fail atomically if a file with the same
7283 name already exists.
7287 The Debian base system provides the <prgn>tempfile</prgn>
7288 and <prgn>mktemp</prgn> utilities for use by scripts for
7295 <heading>Symbolic links</heading>
7298 In general, symbolic links within a top-level directory
7299 should be relative, and symbolic links pointing from one
7300 top-level directory into another should be absolute. (A
7301 top-level directory is a sub-directory of the root
7302 directory <file>/</file>.)
7306 In addition, symbolic links should be specified as short as
7307 possible, i.e., link targets like <file>foo/../bar</file> are
7312 Note that when creating a relative link using
7313 <prgn>ln</prgn> it is not necessary for the target of the
7314 link to exist relative to the working directory you're
7315 running <prgn>ln</prgn> from, nor is it necessary to change
7316 directory to the directory where the link is to be made.
7317 Simply include the string that should appear as the target
7318 of the link (this will be a pathname relative to the
7319 directory in which the link resides) as the first argument
7324 For example, in your <prgn>Makefile</prgn> or
7325 <file>debian/rules</file>, you can do things like:
7326 <example compact="compact">
7327 ln -fs gcc $(prefix)/bin/cc
7328 ln -fs gcc debian/tmp/usr/bin/cc
7329 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7330 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7335 A symbolic link pointing to a compressed file should always
7336 have the same file extension as the referenced file. (For
7337 example, if a file <file>foo.gz</file> is referenced by a
7338 symbolic link, the filename of the link has to end with
7339 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7344 <heading>Device files</heading>
7347 Packages must not include device files or named pipes in the
7352 If a package needs any special device files that are not
7353 included in the base system, it must call
7354 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7355 after notifying the user<footnote>
7356 This notification could be done via a (low-priority)
7357 debconf message, or an echo (printf) statement.
7362 Packages must not remove any device files in the
7363 <prgn>postrm</prgn> or any other script. This is left to the
7364 system administrator.
7368 Debian uses the serial devices
7369 <file>/dev/ttyS*</file>. Programs using the old
7370 <file>/dev/cu*</file> devices should be changed to use
7371 <file>/dev/ttyS*</file>.
7375 Named pipes needed by the package must be created in
7376 the <prgn>postinst</prgn> script<footnote>
7377 It's better to use <prgn>mkfifo</prgn> rather
7378 than <prgn>mknod</prgn> to create named pipes so that
7379 automated checks for packages incorrectly creating device
7380 files with <prgn>mknod</prgn> won't have false positives.
7381 </footnote> and removed in
7382 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7387 <sect id="config-files">
7388 <heading>Configuration files</heading>
7391 <heading>Definitions</heading>
7395 <tag>configuration file</tag>
7397 A file that affects the operation of a program, or
7398 provides site- or host-specific information, or
7399 otherwise customizes the behavior of a program.
7400 Typically, configuration files are intended to be
7401 modified by the system administrator (if needed or
7402 desired) to conform to local policy or to provide
7403 more useful site-specific behavior.
7406 <tag><tt>conffile</tt></tag>
7408 A file listed in a package's <tt>conffiles</tt>
7409 file, and is treated specially by <prgn>dpkg</prgn>
7410 (see <ref id="configdetails">).
7416 The distinction between these two is important; they are
7417 not interchangeable concepts. Almost all
7418 <tt>conffile</tt>s are configuration files, but many
7419 configuration files are not <tt>conffiles</tt>.
7423 As noted elsewhere, <file>/etc/init.d</file> scripts,
7424 <file>/etc/default</file> files, scripts installed in
7425 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7426 configuration installed in <file>/etc/cron.d</file> must be
7427 treated as configuration files. In general, any script that
7428 embeds configuration information is de-facto a configuration
7429 file and should be treated as such.
7434 <heading>Location</heading>
7437 Any configuration files created or used by your package
7438 must reside in <file>/etc</file>. If there are several,
7439 consider creating a subdirectory of <file>/etc</file>
7440 named after your package.
7444 If your package creates or uses configuration files
7445 outside of <file>/etc</file>, and it is not feasible to modify
7446 the package to use <file>/etc</file> directly, put the files
7447 in <file>/etc</file> and create symbolic links to those files
7448 from the location that the package requires.
7453 <heading>Behavior</heading>
7456 Configuration file handling must conform to the following
7458 <list compact="compact">
7460 local changes must be preserved during a package
7464 configuration files must be preserved when the
7465 package is removed, and only deleted when the
7472 The easy way to achieve this behavior is to make the
7473 configuration file a <tt>conffile</tt>. This is
7474 appropriate only if it is possible to distribute a default
7475 version that will work for most installations, although
7476 some system administrators may choose to modify it. This
7477 implies that the default version will be part of the
7478 package distribution, and must not be modified by the
7479 maintainer scripts during installation (or at any other
7484 In order to ensure that local changes are preserved
7485 correctly, no package may contain or make hard links to
7486 conffiles.<footnote>
7487 Rationale: There are two problems with hard links.
7488 The first is that some editors break the link while
7489 editing one of the files, so that the two files may
7490 unwittingly become unlinked and different. The second
7491 is that <prgn>dpkg</prgn> might break the hard link
7492 while upgrading <tt>conffile</tt>s.
7497 The other way to do it is via the maintainer scripts. In
7498 this case, the configuration file must not be listed as a
7499 <tt>conffile</tt> and must not be part of the package
7500 distribution. If the existence of a file is required for
7501 the package to be sensibly configured it is the
7502 responsibility of the package maintainer to provide
7503 maintainer scripts which correctly create, update and
7504 maintain the file and remove it on purge. (See <ref
7505 id="maintainerscripts"> for more information.) These
7506 scripts must be idempotent (i.e., must work correctly if
7507 <prgn>dpkg</prgn> needs to re-run them due to errors
7508 during installation or removal), must cope with all the
7509 variety of ways <prgn>dpkg</prgn> can call maintainer
7510 scripts, must not overwrite or otherwise mangle the user's
7511 configuration without asking, must not ask unnecessary
7512 questions (particularly during upgrades), and must
7513 otherwise be good citizens.
7517 The scripts are not required to configure every possible
7518 option for the package, but only those necessary to get
7519 the package running on a given system. Ideally the
7520 sysadmin should not have to do any configuration other
7521 than that done (semi-)automatically by the
7522 <prgn>postinst</prgn> script.
7526 A common practice is to create a script called
7527 <file><var>package</var>-configure</file> and have the
7528 package's <prgn>postinst</prgn> call it if and only if the
7529 configuration file does not already exist. In certain
7530 cases it is useful for there to be an example or template
7531 file which the maintainer scripts use. Such files should
7532 be in <file>/usr/share/<var>package</var></file> or
7533 <file>/usr/lib/<var>package</var></file> (depending on whether
7534 they are architecture-independent or not). There should
7535 be symbolic links to them from
7536 <file>/usr/share/doc/<var>package</var>/examples</file> if
7537 they are examples, and should be perfectly ordinary
7538 <prgn>dpkg</prgn>-handled files (<em>not</em>
7539 configuration files).
7543 These two styles of configuration file handling must
7544 not be mixed, for that way lies madness:
7545 <prgn>dpkg</prgn> will ask about overwriting the file
7546 every time the package is upgraded.
7551 <heading>Sharing configuration files</heading>
7554 Packages which specify the same file as a
7555 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7556 with each other. (This is an instance of the general rule
7557 about not sharing files. Note that neither alternatives
7558 nor diversions are likely to be appropriate in this case;
7559 in particular, <prgn>dpkg</prgn> does not handle diverted
7560 <tt>conffile</tt>s well.)
7564 The maintainer scripts must not alter a <tt>conffile</tt>
7565 of <em>any</em> package, including the one the scripts
7570 If two or more packages use the same configuration file
7571 and it is reasonable for both to be installed at the same
7572 time, one of these packages must be defined as
7573 <em>owner</em> of the configuration file, i.e., it will be
7574 the package which handles that file as a configuration
7575 file. Other packages that use the configuration file must
7576 depend on the owning package if they require the
7577 configuration file to operate. If the other package will
7578 use the configuration file if present, but is capable of
7579 operating without it, no dependency need be declared.
7583 If it is desirable for two or more related packages to
7584 share a configuration file <em>and</em> for all of the
7585 related packages to be able to modify that configuration
7586 file, then the following should be done:
7587 <enumlist compact="compact">
7589 One of the related packages (the "owning" package)
7590 will manage the configuration file with maintainer
7591 scripts as described in the previous section.
7594 The owning package should also provide a program
7595 that the other packages may use to modify the
7599 The related packages must use the provided program
7600 to make any desired modifications to the
7601 configuration file. They should either depend on
7602 the core package to guarantee that the configuration
7603 modifier program is available or accept gracefully
7604 that they cannot modify the configuration file if it
7605 is not. (This is in addition to the fact that the
7606 configuration file may not even be present in the
7613 Sometimes it's appropriate to create a new package which
7614 provides the basic infrastructure for the other packages
7615 and which manages the shared configuration files. (The
7616 <tt>sgml-base</tt> package is a good example.)
7621 <heading>User configuration files ("dotfiles")</heading>
7624 The files in <file>/etc/skel</file> will automatically be
7625 copied into new user accounts by <prgn>adduser</prgn>.
7626 No other program should reference the files in
7627 <file>/etc/skel</file>.
7631 Therefore, if a program needs a dotfile to exist in
7632 advance in <file>$HOME</file> to work sensibly, that dotfile
7633 should be installed in <file>/etc/skel</file> and treated as a
7638 However, programs that require dotfiles in order to
7639 operate sensibly are a bad thing, unless they do create
7640 the dotfiles themselves automatically.
7644 Furthermore, programs should be configured by the Debian
7645 default installation to behave as closely to the upstream
7646 default behavior as possible.
7650 Therefore, if a program in a Debian package needs to be
7651 configured in some way in order to operate sensibly, that
7652 should be done using a site-wide configuration file placed
7653 in <file>/etc</file>. Only if the program doesn't support a
7654 site-wide default configuration and the package maintainer
7655 doesn't have time to add it may a default per-user file be
7656 placed in <file>/etc/skel</file>.
7660 <file>/etc/skel</file> should be as empty as we can make it.
7661 This is particularly true because there is no easy (or
7662 necessarily desirable) mechanism for ensuring that the
7663 appropriate dotfiles are copied into the accounts of
7664 existing users when a package is installed.
7670 <heading>Log files</heading>
7672 Log files should usually be named
7673 <file>/var/log/<var>package</var>.log</file>. If you have many
7674 log files, or need a separate directory for permission
7675 reasons (<file>/var/log</file> is writable only by
7676 <file>root</file>), you should usually create a directory named
7677 <file>/var/log/<var>package</var></file> and place your log
7682 Log files must be rotated occasionally so that they don't
7683 grow indefinitely; the best way to do this is to drop a log
7684 rotation configuration file into the directory
7685 <file>/etc/logrotate.d</file> and use the facilities provided by
7686 logrotate.<footnote>
7688 The traditional approach to log files has been to set up
7689 <em>ad hoc</em> log rotation schemes using simple shell
7690 scripts and cron. While this approach is highly
7691 customizable, it requires quite a lot of sysadmin work.
7692 Even though the original Debian system helped a little
7693 by automatically installing a system which can be used
7694 as a template, this was deemed not enough.
7698 The use of <prgn>logrotate</prgn>, a program developed
7699 by Red Hat, is better, as it centralizes log management.
7700 It has both a configuration file
7701 (<file>/etc/logrotate.conf</file>) and a directory where
7702 packages can drop their individual log rotation
7703 configurations (<file>/etc/logrotate.d</file>).
7706 Here is a good example for a logrotate config
7707 file (for more information see <manref name="logrotate"
7709 <example compact="compact">
7710 /var/log/foo/*.log {
7715 /etc/init.d/foo force-reload
7719 This rotates all files under <file>/var/log/foo</file>, saves 12
7720 compressed generations, and forces the daemon to reload its
7721 configuration information after the log rotation.
7725 Log files should be removed when the package is
7726 purged (but not when it is only removed). This should be
7727 done by the <prgn>postrm</prgn> script when it is called
7728 with the argument <tt>purge</tt> (see <ref
7729 id="removedetails">).
7734 <heading>Permissions and owners</heading>
7737 The rules in this section are guidelines for general use.
7738 If necessary you may deviate from the details below.
7739 However, if you do so you must make sure that what is done
7740 is secure and you should try to be as consistent as possible
7741 with the rest of the system. You should probably also
7742 discuss it on <prgn>debian-devel</prgn> first.
7746 Files should be owned by <tt>root:root</tt>, and made
7747 writable only by the owner and universally readable (and
7748 executable, if appropriate), that is mode 644 or 755.
7752 Directories should be mode 755 or (for group-writability)
7753 mode 2775. The ownership of the directory should be
7754 consistent with its mode: if a directory is mode 2775, it
7755 should be owned by the group that needs write access to
7758 When a package is upgraded, and the owner or permissions
7759 of a file included in the package has changed, dpkg
7760 arranges for the ownership and permissions to be
7761 correctly set upon installation. However, this does not
7762 extend to directories; the permissions and ownership of
7763 directories already on the system does not change on
7764 install or upgrade of packages. This makes sense, since
7765 otherwise common directories like <tt>/usr</tt> would
7766 always be in flux. To correctly change permissions of a
7767 directory the package owns, explicit action is required,
7768 usually in the <tt>postinst</tt> script. Care must be
7769 taken to handle downgrades as well, in that case.
7776 Setuid and setgid executables should be mode 4755 or 2755
7777 respectively, and owned by the appropriate user or group.
7778 They should not be made unreadable (modes like 4711 or
7779 2711 or even 4111); doing so achieves no extra security,
7780 because anyone can find the binary in the freely available
7781 Debian package; it is merely inconvenient. For the same
7782 reason you should not restrict read or execute permissions
7783 on non-set-id executables.
7787 Some setuid programs need to be restricted to particular
7788 sets of users, using file permissions. In this case they
7789 should be owned by the uid to which they are set-id, and by
7790 the group which should be allowed to execute them. They
7791 should have mode 4754; again there is no point in making
7792 them unreadable to those users who must not be allowed to
7797 It is possible to arrange that the system administrator can
7798 reconfigure the package to correspond to their local
7799 security policy by changing the permissions on a binary:
7800 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7801 described below.<footnote>
7802 Ordinary files installed by <prgn>dpkg</prgn> (as
7803 opposed to <tt>conffile</tt>s and other similar objects)
7804 normally have their permissions reset to the distributed
7805 permissions when the package is reinstalled. However,
7806 the use of <prgn>dpkg-statoverride</prgn> overrides this
7807 default behavior. If you use this method, you should
7808 remember to describe <prgn>dpkg-statoverride</prgn> in
7809 the package documentation; being a relatively new
7810 addition to Debian, it is probably not yet well-known.
7812 Another method you should consider is to create a group for
7813 people allowed to use the program(s) and make any setuid
7814 executables executable only by that group.
7818 If you need to create a new user or group for your package
7819 there are two possibilities. Firstly, you may need to
7820 make some files in the binary package be owned by this
7821 user or group, or you may need to compile the user or
7822 group id (rather than just the name) into the binary
7823 (though this latter should be avoided if possible, as in
7824 this case you need a statically allocated id).</p>
7827 If you need a statically allocated id, you must ask for a
7828 user or group id from the <tt>base-passwd</tt> maintainer,
7829 and must not release the package until you have been
7830 allocated one. Once you have been allocated one you must
7831 either make the package depend on a version of the
7832 <tt>base-passwd</tt> package with the id present in
7833 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7834 your package to create the user or group itself with the
7835 correct id (using <tt>adduser</tt>) in its
7836 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7837 the <prgn>postinst</prgn> is to be preferred if it is
7838 possible, otherwise a pre-dependency will be needed on the
7839 <tt>adduser</tt> package.)
7843 On the other hand, the program might be able to determine
7844 the uid or gid from the user or group name at runtime, so
7845 that a dynamically allocated id can be used. In this case
7846 you should choose an appropriate user or group name,
7847 discussing this on <prgn>debian-devel</prgn> and checking
7848 with the <package/base-passwd/ maintainer that it is unique and that
7849 they do not wish you to use a statically allocated id
7850 instead. When this has been checked you must arrange for
7851 your package to create the user or group if necessary using
7852 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7853 <prgn>postinst</prgn> script (again, the latter is to be
7854 preferred if it is possible).
7858 Note that changing the numeric value of an id associated
7859 with a name is very difficult, and involves searching the
7860 file system for all appropriate files. You need to think
7861 carefully whether a static or dynamic id is required, since
7862 changing your mind later will cause problems.
7865 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7867 This section is not intended as policy, but as a
7868 description of the use of <prgn>dpkg-statoverride</prgn>.
7872 If a system administrator wishes to have a file (or
7873 directory or other such thing) installed with owner and
7874 permissions different from those in the distributed Debian
7875 package, they can use the <prgn>dpkg-statoverride</prgn>
7876 program to instruct <prgn>dpkg</prgn> to use the different
7877 settings every time the file is installed. Thus the
7878 package maintainer should distribute the files with their
7879 normal permissions, and leave it for the system
7880 administrator to make any desired changes. For example, a
7881 daemon which is normally required to be setuid root, but
7882 in certain situations could be used without being setuid,
7883 should be installed setuid in the <tt>.deb</tt>. Then the
7884 local system administrator can change this if they wish.
7885 If there are two standard ways of doing it, the package
7886 maintainer can use <tt>debconf</tt> to find out the
7887 preference, and call <prgn>dpkg-statoverride</prgn> in the
7888 maintainer script if necessary to accommodate the system
7889 administrator's choice. Care must be taken during
7890 upgrades to not override an existing setting.
7894 Given the above, <prgn>dpkg-statoverride</prgn> is
7895 essentially a tool for system administrators and would not
7896 normally be needed in the maintainer scripts. There is
7897 one type of situation, though, where calls to
7898 <prgn>dpkg-statoverride</prgn> would be needed in the
7899 maintainer scripts, and that involves packages which use
7900 dynamically allocated user or group ids. In such a
7901 situation, something like the following idiom can be very
7902 helpful in the package's <prgn>postinst</prgn>, where
7903 <tt>sysuser</tt> is a dynamically allocated id:
7905 for i in /usr/bin/foo /usr/sbin/bar
7907 # only do something when no setting exists
7908 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7910 #include: debconf processing, question about foo and bar
7911 if [ "$RET" = "true" ] ; then
7912 dpkg-statoverride --update --add sysuser root 4755 $i
7917 The corresponding code to remove the override when the package
7920 for i in /usr/bin/foo /usr/sbin/bar
7922 if dpkg-statoverride --list $i >/dev/null 2>&1
7924 dpkg-statoverride --remove $i
7934 <chapt id="customized-programs">
7935 <heading>Customized programs</heading>
7937 <sect id="arch-spec">
7938 <heading>Architecture specification strings</heading>
7941 If a program needs to specify an <em>architecture specification
7942 string</em> in some place, it should select one of the
7943 strings provided by <tt>dpkg-architecture -L</tt>. The
7944 strings are in the format
7945 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7946 is sometimes elided, as when the OS is Linux.<footnote>
7947 <p>Currently, the strings are:
7948 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7949 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7950 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7951 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7952 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7953 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7954 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7955 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7956 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7957 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7958 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7959 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7960 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7961 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7962 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7963 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7964 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7965 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7966 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7967 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7968 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7969 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7970 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7971 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7972 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7973 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7974 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7975 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7976 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7977 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7978 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7979 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7980 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7981 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7982 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7983 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7984 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7990 Note that we don't want to use
7991 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7992 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7993 since this would make our programs incompatible with other
7994 Linux distributions. We also don't use something like
7995 <tt><var>arch</var>-unknown-linux</tt>, since the
7996 <tt>unknown</tt> does not look very good.
8000 <sect id="arch-wildcard-spec">
8001 <heading>Architecture Wildcards</heading>
8004 A package may specify an architecture wildcard. Architecture
8005 wildcards are in the format <tt><var>os</var></tt>-any and
8006 any-<tt><var>cpu</var></tt>. <footnote>Internally, the package
8007 system normalizes the GNU triplets and the Debian
8008 arches into Debian arch triplets (which are kind of inverted GNU
8009 triplets). So when matching two Debian arch triplets, whenever an
8010 <var>any</var> is found it matches with anything on the other side,
8013 gnu-linux-i386 is matched by gnu-linux-any
8014 gnu-kfreebsd-amd64 is matched by any-any-amd64
8016 And for example <var>any</var> is normalized to <var>any-any-any</var>.
8022 <heading>Daemons</heading>
8025 The configuration files <file>/etc/services</file>,
8026 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8027 by the <prgn>netbase</prgn> package and must not be modified
8032 If a package requires a new entry in one of these files, the
8033 maintainer should get in contact with the
8034 <prgn>netbase</prgn> maintainer, who will add the entries
8035 and release a new version of the <prgn>netbase</prgn>
8040 The configuration file <file>/etc/inetd.conf</file> must not be
8041 modified by the package's scripts except via the
8042 <prgn>update-inetd</prgn> script or the
8043 <file>DebianNet.pm</file> Perl module. See their documentation
8044 for details on how to add entries.
8048 If a package wants to install an example entry into
8049 <file>/etc/inetd.conf</file>, the entry must be preceded with
8050 exactly one hash character (<tt>#</tt>). Such lines are
8051 treated as "commented out by user" by the
8052 <prgn>update-inetd</prgn> script and are not changed or
8053 activated during package updates.
8058 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8062 Some programs need to create pseudo-ttys. This should be done
8063 using Unix98 ptys if the C library supports it. The resulting
8064 program must not be installed setuid root, unless that
8065 is required for other functionality.
8069 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8070 <file>/var/log/lastlog</file> must be installed writable by
8071 group <tt>utmp</tt>. Programs which need to modify those
8072 files must be installed setgid <tt>utmp</tt>.
8077 <heading>Editors and pagers</heading>
8080 Some programs have the ability to launch an editor or pager
8081 program to edit or display a text document. Since there are
8082 lots of different editors and pagers available in the Debian
8083 distribution, the system administrator and each user should
8084 have the possibility to choose their preferred editor and
8089 In addition, every program should choose a good default
8090 editor/pager if none is selected by the user or system
8095 Thus, every program that launches an editor or pager must
8096 use the EDITOR or PAGER environment variable to determine
8097 the editor or pager the user wishes to use. If these
8098 variables are not set, the programs <file>/usr/bin/editor</file>
8099 and <file>/usr/bin/pager</file> should be used, respectively.
8103 These two files are managed through the <prgn>dpkg</prgn>
8104 "alternatives" mechanism. Thus every package providing an
8105 editor or pager must call the
8106 <prgn>update-alternatives</prgn> script to register these
8111 If it is very hard to adapt a program to make use of the
8112 EDITOR or PAGER variables, that program may be configured to
8113 use <file>/usr/bin/sensible-editor</file> and
8114 <file>/usr/bin/sensible-pager</file> as the editor or pager
8115 program respectively. These are two scripts provided in the
8116 <package>sensible-utils</package> package that check the EDITOR
8117 and PAGER variables and launch the appropriate program, and fall
8118 back to <file>/usr/bin/editor</file>
8119 and <file>/usr/bin/pager</file> if the variable is not set.
8123 A program may also use the VISUAL environment variable to
8124 determine the user's choice of editor. If it exists, it
8125 should take precedence over EDITOR. This is in fact what
8126 <file>/usr/bin/sensible-editor</file> does.
8130 It is not required for a package to depend on
8131 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8132 package to provide such virtual packages.<footnote>
8133 The Debian base system already provides an editor and a
8139 <sect id="web-appl">
8140 <heading>Web servers and applications</heading>
8143 This section describes the locations and URLs that should
8144 be used by all web servers and web applications in the
8151 Cgi-bin executable files are installed in the
8153 <example compact="compact">
8154 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8156 and should be referred to as
8157 <example compact="compact">
8158 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8164 <p>Access to HTML documents</p>
8167 HTML documents for a package are stored in
8168 <file>/usr/share/doc/<var>package</var></file>
8169 and can be referred to as
8170 <example compact="compact">
8171 http://localhost/doc/<var>package</var>/<var>filename</var>
8176 The web server should restrict access to the document
8177 tree so that only clients on the same host can read
8178 the documents. If the web server does not support such
8179 access controls, then it should not provide access at
8180 all, or ask about providing access during installation.
8185 <p>Access to images</p>
8187 It is recommended that images for a package be stored
8188 in <tt>/usr/share/images/<var>package</var></tt> and
8189 may be referred to through an alias <tt>/images/</tt>
8192 http://localhost/images/<package>/<filename>
8199 <p>Web Document Root</p>
8202 Web Applications should try to avoid storing files in
8203 the Web Document Root. Instead they should use the
8204 /usr/share/doc/<var>package</var> directory for
8205 documents and register the Web Application via the
8206 <package>doc-base</package> package. If access to the
8207 web document root is unavoidable then use
8208 <example compact="compact">
8211 as the Document Root. This might be just a symbolic
8212 link to the location where the system administrator
8213 has put the real document root.
8216 <item><p>Providing httpd and/or httpd-cgi</p>
8218 All web servers should provide the virtual package
8219 <tt>httpd</tt>. If a web server has CGI support it should
8220 provide <tt>httpd-cgi</tt> additionally.
8223 All web applications which do not contain CGI scripts should
8224 depend on <tt>httpd</tt>, all those web applications which
8225 <tt>do</tt> contain CGI scripts, should depend on
8233 <sect id="mail-transport-agents">
8234 <heading>Mail transport, delivery and user agents</heading>
8237 Debian packages which process electronic mail, whether mail
8238 user agents (MUAs) or mail transport agents (MTAs), must
8239 ensure that they are compatible with the configuration
8240 decisions below. Failure to do this may result in lost
8241 mail, broken <tt>From:</tt> lines, and other serious brain
8246 The mail spool is <file>/var/mail</file> and the interface to
8247 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8248 the FHS). On older systems, the mail spool may be
8249 physically located in <file>/var/spool/mail</file>, but all
8250 access to the mail spool should be via the
8251 <file>/var/mail</file> symlink. The mail spool is part of the
8252 base system and not part of the MTA package.
8256 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8257 programs (such as IMAP daemons) must lock the mailbox in an
8258 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8259 be combined with dot locking. To avoid deadlocks, a program
8260 should use <tt>fcntl()</tt> first and dot locking after
8261 this, or alternatively implement the two locking methods in
8262 a non blocking way<footnote>
8263 If it is not possible to establish both locks, the
8264 system shouldn't wait for the second lock to be
8265 established, but remove the first lock, wait a (random)
8266 time, and start over locking again.
8267 </footnote>. Using the functions <tt>maillock</tt> and
8268 <tt>mailunlock</tt> provided by the
8269 <tt>liblockfile*</tt><footnote>
8270 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8271 to use these functions.
8272 </footnote> packages is the recommended way to realize this.
8276 Mailboxes are generally either mode 600 and owned by
8277 <var>user</var> or mode 660 and owned by
8278 <tt><var>user</var>:mail</tt><footnote>
8279 There are two traditional permission schemes for mail spools:
8280 mode 600 with all mail delivery done by processes running as
8281 the destination user, or mode 660 and owned by group mail with
8282 mail delivery done by a process running as a system user in
8283 group mail. Historically, Debian required mode 660 mail
8284 spools to enable the latter model, but that model has become
8285 increasingly uncommon and the principle of least privilege
8286 indicates that mail systems that use the first model should
8287 use permissions of 600. If delivery to programs is permitted,
8288 it's easier to keep the mail system secure if the delivery
8289 agent runs as the destination user. Debian Policy therefore
8290 permits either scheme.
8291 </footnote>. The local system administrator may choose a
8292 different permission scheme; packages should not make
8293 assumptions about the permission and ownership of mailboxes
8294 unless required (such as when creating a new mailbox). A MUA
8295 may remove a mailbox (unless it has nonstandard permissions) in
8296 which case the MTA or another MUA must recreate it if needed.
8300 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8301 be setgid mail to do the locking mentioned above (and
8302 must obviously avoid accessing other users' mailboxes
8303 using this privilege).</p>
8306 <file>/etc/aliases</file> is the source file for the system mail
8307 aliases (e.g., postmaster, usenet, etc.), it is the one
8308 which the sysadmin and <prgn>postinst</prgn> scripts may
8309 edit. After <file>/etc/aliases</file> is edited the program or
8310 human editing it must call <prgn>newaliases</prgn>. All MTA
8311 packages must come with a <prgn>newaliases</prgn> program,
8312 even if it does nothing, but older MTA packages did not do
8313 this so programs should not fail if <prgn>newaliases</prgn>
8314 cannot be found. Note that because of this, all MTA
8315 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8316 <tt>Replaces: mail-transport-agent</tt> control file
8321 The convention of writing <tt>forward to
8322 <var>address</var></tt> in the mailbox itself is not
8323 supported. Use a <tt>.forward</tt> file instead.</p>
8326 The <prgn>rmail</prgn> program used by UUCP
8327 for incoming mail should be <file>/usr/sbin/rmail</file>.
8328 Likewise, <prgn>rsmtp</prgn>, for receiving
8329 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8333 If your package needs to know what hostname to use on (for
8334 example) outgoing news and mail messages which are generated
8335 locally, you should use the file <file>/etc/mailname</file>. It
8336 will contain the portion after the username and <tt>@</tt>
8337 (at) sign for email addresses of users on the machine
8338 (followed by a newline).
8342 Such a package should check for the existence of this file
8343 when it is being configured. If it exists, it should be
8344 used without comment, although an MTA's configuration script
8345 may wish to prompt the user even if it finds that this file
8346 exists. If the file does not exist, the package should
8347 prompt the user for the value (preferably using
8348 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8349 as well as using it in the package's configuration. The
8350 prompt should make it clear that the name will not just be
8351 used by that package. For example, in this situation the
8352 <tt>inn</tt> package could say something like:
8353 <example compact="compact">
8354 Please enter the "mail name" of your system. This is the
8355 hostname portion of the address to be shown on outgoing
8356 news and mail messages. The default is
8357 <var>syshostname</var>, your system's host name. Mail
8358 name ["<var>syshostname</var>"]:
8360 where <var>syshostname</var> is the output of <tt>hostname
8366 <heading>News system configuration</heading>
8369 All the configuration files related to the NNTP (news)
8370 servers and clients should be located under
8371 <file>/etc/news</file>.</p>
8374 There are some configuration issues that apply to a number
8375 of news clients and server packages on the machine. These
8379 <tag><file>/etc/news/organization</file></tag>
8381 A string which should appear as the
8382 organization header for all messages posted
8383 by NNTP clients on the machine
8386 <tag><file>/etc/news/server</file></tag>
8388 Contains the FQDN of the upstream NNTP
8389 server, or localhost if the local machine is
8394 Other global files may be added as required for cross-package news
8401 <heading>Programs for the X Window System</heading>
8404 <heading>Providing X support and package priorities</heading>
8407 Programs that can be configured with support for the X
8408 Window System must be configured to do so and must declare
8409 any package dependencies necessary to satisfy their
8410 runtime requirements when using the X Window System. If
8411 such a package is of higher priority than the X packages
8412 on which it depends, it is required that either the
8413 X-specific components be split into a separate package, or
8414 that an alternative version of the package, which includes
8415 X support, be provided, or that the package's priority be
8421 <heading>Packages providing an X server</heading>
8424 Packages that provide an X server that, directly or
8425 indirectly, communicates with real input and display
8426 hardware should declare in their control data that they
8427 provide the virtual package <tt>xserver</tt>.<footnote>
8428 This implements current practice, and provides an
8429 actual policy for usage of the <tt>xserver</tt>
8430 virtual package which appears in the virtual packages
8431 list. In a nutshell, X servers that interface
8432 directly with the display and input hardware or via
8433 another subsystem (e.g., GGI) should provide
8434 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8435 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8441 <heading>Packages providing a terminal emulator</heading>
8444 Packages that provide a terminal emulator for the X Window
8445 System which meet the criteria listed below should declare
8446 in their control data that they provide the virtual
8447 package <tt>x-terminal-emulator</tt>. They should also
8448 register themselves as an alternative for
8449 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8454 To be an <tt>x-terminal-emulator</tt>, a program must:
8455 <list compact="compact">
8457 Be able to emulate a DEC VT100 terminal, or a
8458 compatible terminal.
8462 Support the command-line option <tt>-e
8463 <var>command</var></tt>, which creates a new
8464 terminal window<footnote>
8465 "New terminal window" does not necessarily mean
8466 a new top-level X window directly parented by
8467 the window manager; it could, if the terminal
8468 emulator application were so coded, be a new
8469 "view" in a multiple-document interface (MDI).
8471 and runs the specified <var>command</var>,
8472 interpreting the entirety of the rest of the command
8473 line as a command to pass straight to exec, in the
8474 manner that <tt>xterm</tt> does.
8478 Support the command-line option <tt>-T
8479 <var>title</var></tt>, which creates a new terminal
8480 window with the window title <var>title</var>.
8487 <heading>Packages providing a window manager</heading>
8490 Packages that provide a window manager should declare in
8491 their control data that they provide the virtual package
8492 <tt>x-window-manager</tt>. They should also register
8493 themselves as an alternative for
8494 <file>/usr/bin/x-window-manager</file>, with a priority
8495 calculated as follows:
8496 <list compact="compact">
8498 Start with a priority of 20.
8502 If the window manager supports the Debian menu
8503 system, add 20 points if this support is available
8504 in the package's default configuration (i.e., no
8505 configuration files belonging to the system or user
8506 have to be edited to activate the feature); if
8507 configuration files must be modified, add only 10
8513 If the window manager complies with <url
8514 id="http://www.freedesktop.org/Standards/wm-spec"
8515 name="The Window Manager Specification Project">,
8516 written by the <url id="http://www.freedesktop.org/"
8517 name="Free Desktop Group">, add 40 points.
8521 If the window manager permits the X session to be
8522 restarted using a <em>different</em> window manager
8523 (without killing the X server) in its default
8524 configuration, add 10 points; otherwise add none.
8531 <heading>Packages providing fonts</heading>
8534 Packages that provide fonts for the X Window
8536 For the purposes of Debian Policy, a "font for the X
8537 Window System" is one which is accessed via X protocol
8538 requests. Fonts for the Linux console, for PostScript
8539 renderer, or any other purpose, do not fit this
8540 definition. Any tool which makes such fonts available
8541 to the X Window System, however, must abide by this
8544 must do a number of things to ensure that they are both
8545 available without modification of the X or font server
8546 configuration, and that they do not corrupt files used by
8547 other font packages to register information about
8551 Fonts of any type supported by the X Window System
8552 must be in a separate binary package from any
8553 executables, libraries, or documentation (except
8554 that specific to the fonts shipped, such as their
8555 license information). If one or more of the fonts
8556 so packaged are necessary for proper operation of
8557 the package with which they are associated the font
8558 package may be Recommended; if the fonts merely
8559 provide an enhancement, a Suggests relationship may
8560 be used. Packages must not Depend on font
8562 This is because the X server may retrieve fonts
8563 from the local file system or over the network
8564 from an X font server; the Debian package system
8565 is empowered to deal only with the local
8571 BDF fonts must be converted to PCF fonts with the
8572 <prgn>bdftopcf</prgn> utility (available in the
8573 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8574 placed in a directory that corresponds to their
8576 <list compact="compact">
8578 100 dpi fonts must be placed in
8579 <file>/usr/share/fonts/X11/100dpi/</file>.
8583 75 dpi fonts must be placed in
8584 <file>/usr/share/fonts/X11/75dpi/</file>.
8588 Character-cell fonts, cursor fonts, and other
8589 low-resolution fonts must be placed in
8590 <file>/usr/share/fonts/X11/misc/</file>.
8596 Type 1 fonts must be placed in
8597 <file>/usr/share/fonts/X11/Type1/</file>. If font
8598 metric files are available, they must be placed here
8603 Subdirectories of <file>/usr/share/fonts/X11/</file>
8604 other than those listed above must be neither
8605 created nor used. (The <file>PEX</file>, <file>CID</file>,
8606 <file>Speedo</file>, and <file>cyrillic</file> directories
8607 are excepted for historical reasons, but installation of
8608 files into these directories remains discouraged.)
8612 Font packages may, instead of placing files directly
8613 in the X font directories listed above, provide
8614 symbolic links in that font directory pointing to
8615 the files' actual location in the filesystem. Such
8616 a location must comply with the FHS.
8620 Font packages should not contain both 75dpi and
8621 100dpi versions of a font. If both are available,
8622 they should be provided in separate binary packages
8623 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8624 the names of the packages containing the
8625 corresponding fonts.
8629 Fonts destined for the <file>misc</file> subdirectory
8630 should not be included in the same package as 75dpi
8631 or 100dpi fonts; instead, they should be provided in
8632 a separate package with <tt>-misc</tt> appended to
8637 Font packages must not provide the files
8638 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8639 <file>fonts.scale</file> in a font directory:
8642 <file>fonts.dir</file> files must not be provided at all.
8646 <file>fonts.alias</file> and <file>fonts.scale</file>
8647 files, if needed, should be provided in the
8649 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8650 where <var>fontdir</var> is the name of the
8652 <file>/usr/share/fonts/X11/</file> where the
8653 package's corresponding fonts are stored
8654 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8655 <var>package</var> is the name of the package
8656 that provides these fonts, and
8657 <var>extension</var> is either <tt>scale</tt>
8658 or <tt>alias</tt>, whichever corresponds to
8665 Font packages must declare a dependency on
8666 <tt>xfonts-utils</tt> in their control
8671 Font packages that provide one or more
8672 <file>fonts.scale</file> files as described above must
8673 invoke <prgn>update-fonts-scale</prgn> on each
8674 directory into which they installed fonts
8675 <em>before</em> invoking
8676 <prgn>update-fonts-dir</prgn> on that directory.
8677 This invocation must occur in both the
8678 <prgn>postinst</prgn> (for all arguments) and
8679 <prgn>postrm</prgn> (for all arguments except
8680 <tt>upgrade</tt>) scripts.
8684 Font packages that provide one or more
8685 <file>fonts.alias</file> files as described above must
8686 invoke <prgn>update-fonts-alias</prgn> on each
8687 directory into which they installed fonts. This
8688 invocation must occur in both the
8689 <prgn>postinst</prgn> (for all arguments) and
8690 <prgn>postrm</prgn> (for all arguments except
8691 <tt>upgrade</tt>) scripts.
8695 Font packages must invoke
8696 <prgn>update-fonts-dir</prgn> on each directory into
8697 which they installed fonts. This invocation must
8698 occur in both the <prgn>postinst</prgn> (for all
8699 arguments) and <prgn>postrm</prgn> (for all
8700 arguments except <tt>upgrade</tt>) scripts.
8704 Font packages must not provide alias names for the
8705 fonts they include which collide with alias names
8706 already in use by fonts already packaged.
8710 Font packages must not provide fonts with the same
8711 XLFD registry name as another font already packaged.
8717 <sect1 id="appdefaults">
8718 <heading>Application defaults files</heading>
8721 Application defaults files must be installed in the
8722 directory <file>/etc/X11/app-defaults/</file> (use of a
8723 localized subdirectory of <file>/etc/X11/</file> as described
8724 in the <em>X Toolkit Intrinsics - C Language
8725 Interface</em> manual is also permitted). They must be
8726 registered as <tt>conffile</tt>s or handled as
8727 configuration files.
8731 Customization of programs' X resources may also be
8732 supported with the provision of a file with the same name
8733 as that of the package placed in
8734 the <file>/etc/X11/Xresources/</file> directory, which
8735 must be registered as a <tt>conffile</tt> or handled as a
8736 configuration file.<footnote>
8737 Note that this mechanism is not the same as using
8738 app-defaults; app-defaults are tied to the client
8739 binary on the local file system, whereas X resources
8740 are stored in the X server and affect all connecting
8747 <heading>Installation directory issues</heading>
8750 Historically, packages using the X Window System used a
8751 separate set of installation directories from other packages.
8752 This practice has been discontinued and packages using the X
8753 Window System should now generally be installed in the same
8754 directories as any other package. Specifically, packages must
8755 not install files under the <file>/usr/X11R6/</file> directory
8756 and the <file>/usr/X11R6/</file> directory hierarchy should be
8757 regarded as obsolete.
8761 Include files previously installed under
8762 <file>/usr/X11R6/include/X11/</file> should be installed into
8763 <file>/usr/include/X11/</file>. For files previously
8764 installed into subdirectories of
8765 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8766 determine if subdirectories of <file>/usr/lib/</file> and
8767 <file>/usr/share/</file> can be used. If not, a subdirectory
8768 of <file>/usr/lib/X11/</file> should be used.
8772 Configuration files for window, display, or session managers
8773 or other applications that are tightly integrated with the X
8774 Window System may be placed in a subdirectory
8775 of <file>/etc/X11/</file> corresponding to the package name.
8776 Other X Window System applications should use
8777 the <file>/etc/</file> directory unless otherwise mandated by
8778 policy (such as for <ref id="appdefaults">).
8783 <heading>The OSF/Motif and OpenMotif libraries</heading>
8786 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8787 OpenMotif libraries</em><footnote>
8788 OSF/Motif and OpenMotif are collectively referred to as
8789 "Motif" in this policy document.
8791 should be compiled against and tested with LessTif (a free
8792 re-implementation of Motif) instead. If the maintainer
8793 judges that the program or programs do not work
8794 sufficiently well with LessTif to be distributed and
8795 supported, but do so when compiled against Motif, then two
8796 versions of the package should be created; one linked
8797 statically against Motif and with <tt>-smotif</tt>
8798 appended to the package name, and one linked dynamically
8799 against Motif and with <tt>-dmotif</tt> appended to the
8804 Both Motif-linked versions are dependent
8805 upon non-DFSG-compliant software and thus cannot be
8806 uploaded to the <em>main</em> distribution; if the
8807 software is itself DFSG-compliant it may be uploaded to
8808 the <em>contrib</em> distribution. While known existing
8809 versions of Motif permit unlimited redistribution of
8810 binaries linked against the library (whether statically or
8811 dynamically), it is the package maintainer's
8812 responsibility to determine whether this is permitted by
8813 the license of the copy of Motif in their possession.
8819 <heading>Perl programs and modules</heading>
8822 Perl programs and modules should follow the current Perl policy.
8826 The Perl policy can be found in the <tt>perl-policy</tt>
8827 files in the <tt>debian-policy</tt> package.
8828 It is also available from the Debian web mirrors at
8829 <tt><url name="/doc/packaging-manuals/perl-policy/"
8830 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8835 <heading>Emacs lisp programs</heading>
8838 Please refer to the "Debian Emacs Policy" for details of how to
8839 package emacs lisp programs.
8843 The Emacs policy is available in
8844 <file>debian-emacs-policy.gz</file> of the
8845 <package>emacsen-common</package> package.
8846 It is also available from the Debian web mirrors at
8847 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8848 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8853 <heading>Games</heading>
8856 The permissions on <file>/var/games</file> are mode 755, owner
8857 <tt>root</tt> and group <tt>root</tt>.
8861 Each game decides on its own security policy.</p>
8864 Games which require protected, privileged access to
8865 high-score files, saved games, etc., may be made
8866 set-<em>group</em>-id (mode 2755) and owned by
8867 <tt>root:games</tt>, and use files and directories with
8868 appropriate permissions (770 <tt>root:games</tt>, for
8869 example). They must not be made
8870 set-<em>user</em>-id, as this causes security problems. (If
8871 an attacker can subvert any set-user-id game they can
8872 overwrite the executable of any other, causing other players
8873 of these games to run a Trojan horse program. With a
8874 set-group-id game the attacker only gets access to less
8875 important game data, and if they can get at the other
8876 players' accounts at all it will take considerably more
8880 Some packages, for example some fortune cookie programs, are
8881 configured by the upstream authors to install with their
8882 data files or other static information made unreadable so
8883 that they can only be accessed through set-id programs
8884 provided. You should not do this in a Debian package: anyone can
8885 download the <file>.deb</file> file and read the data from it,
8886 so there is no point making the files unreadable. Not
8887 making the files unreadable also means that you don't have
8888 to make so many programs set-id, which reduces the risk of a
8892 As described in the FHS, binaries of games should be
8893 installed in the directory <file>/usr/games</file>. This also
8894 applies to games that use the X Window System. Manual pages
8895 for games (X and non-X games) should be installed in
8896 <file>/usr/share/man/man6</file>.</p>
8902 <heading>Documentation</heading>
8905 <heading>Manual pages</heading>
8908 You should install manual pages in <prgn>nroff</prgn> source
8909 form, in appropriate places under <file>/usr/share/man</file>.
8910 You should only use sections 1 to 9 (see the FHS for more
8911 details). You must not install a pre-formatted "cat page".
8915 Each program, utility, and function should have an
8916 associated manual page included in the same package. It is
8917 suggested that all configuration files also have a manual
8918 page included as well. Manual pages for protocols and other
8919 auxiliary things are optional.
8923 If no manual page is available, this is considered as a bug
8924 and should be reported to the Debian Bug Tracking System (the
8925 maintainer of the package is allowed to write this bug report
8926 themselves, if they so desire). Do not close the bug report
8927 until a proper man page is available.<footnote>
8928 It is not very hard to write a man page. See the
8929 <url id="http://www.schweikhardt.net/man_page_howto.html"
8930 name="Man-Page-HOWTO">,
8931 <manref name="man" section="7">, the examples
8932 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8933 the helper programs <prgn>help2man</prgn>, or the
8934 directory <file>/usr/share/doc/man-db/examples</file>.
8939 You may forward a complaint about a missing man page to the
8940 upstream authors, and mark the bug as forwarded in the
8941 Debian bug tracking system. Even though the GNU Project do
8942 not in general consider the lack of a man page to be a bug,
8943 we do; if they tell you that they don't consider it a bug
8944 you should leave the bug in our bug tracking system open
8949 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8953 If one man page needs to be accessible via several names it
8954 is better to use a symbolic link than the <file>.so</file>
8955 feature, but there is no need to fiddle with the relevant
8956 parts of the upstream source to change from <file>.so</file> to
8957 symlinks: don't do it unless it's easy. You should not
8958 create hard links in the manual page directories, nor put
8959 absolute filenames in <file>.so</file> directives. The filename
8960 in a <file>.so</file> in a man page should be relative to the
8961 base of the man page tree (usually
8962 <file>/usr/share/man</file>). If you do not create any links
8963 (whether symlinks, hard links, or <tt>.so</tt> directives)
8964 in the file system to the alternate names of the man page,
8965 then you should not rely on <prgn>man</prgn> finding your
8966 man page under those names based solely on the information in
8967 the man page's header.<footnote>
8968 Supporting this in <prgn>man</prgn> often requires
8969 unreasonable processing time to find a manual page or to
8970 report that none exists, and moves knowledge into man's
8971 database that would be better left in the file system.
8972 This support is therefore deprecated and will cease to
8973 be present in the future.
8978 Manual pages in locale-specific subdirectories of
8979 <file>/usr/share/man</file> should use either UTF-8 or the usual
8980 legacy encoding for that language (normally the one corresponding
8981 to the shortest relevant locale name in
8982 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8983 <file>/usr/share/man/fr</file> should use either UTF-8 or
8984 ISO-8859-1.<footnote>
8985 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8986 use. In future, all manual pages will be required to use
8992 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8993 included in the subdirectory name unless it indicates a
8994 significant difference in the language, as this excludes
8995 speakers of the language in other countries.<footnote>
8996 At the time of writing, Chinese and Portuguese are the main
8997 languages with such differences, so <file>pt_BR</file>,
8998 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9003 If a localized version of a manual page is provided, it should
9004 either be up-to-date or it should be obvious to the reader that
9005 it is outdated and the original manual page should be used
9006 instead. This can be done either by a note at the beginning of
9007 the manual page or by showing the missing or changed portions in
9008 the original language instead of the target language.
9013 <heading>Info documents</heading>
9016 Info documents should be installed in <file>/usr/share/info</file>.
9017 They should be compressed with <tt>gzip -9</tt>.
9021 The <prgn>install-info</prgn> program maintains a directory of
9022 installed info documents in <file>/usr/share/info/dir</file> for
9023 the use of info readers.<footnote>
9024 It was previously necessary for packages installing info
9025 documents to run <prgn>install-info</prgn> from maintainer
9026 scripts. This is no longer necessary. The installation
9027 system now uses dpkg triggers.
9029 This file must not be included in packages. Packages containing
9030 info documents should depend on <tt>dpkg (>= 1.15.4) |
9031 install-info</tt> to ensure that the directory file is properly
9032 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9037 Info documents should contain section and directory entry
9038 information in the document for the use
9039 of <prgn>install-info</prgn>. The section should be specified
9040 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9041 space and the section of this info page. The directory entry or
9042 entries should be included between
9043 a <tt>START-INFO-DIR-ENTRY</tt> line and
9044 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9046 INFO-DIR-SECTION Individual utilities
9047 START-INFO-DIR-ENTRY
9048 * example: (example). An example info directory entry.
9051 To determine which section to use, you should look
9052 at <file>/usr/share/info/dir</file> on your system and choose
9053 the most relevant (or create a new section if none of the
9054 current sections are relevant).<footnote>
9055 Normally, info documents are generated from Texinfo source.
9056 To include this information in the generated info document, if
9057 it is absent, add commands like:
9059 @dircategory Individual utilities
9061 * example: (example). An example info directory entry.
9064 to the Texinfo source of the document and ensure that the info
9065 documents are rebuilt from source during the package build.
9071 <heading>Additional documentation</heading>
9074 Any additional documentation that comes with the package may
9075 be installed at the discretion of the package maintainer.
9076 Plain text documentation should be installed in the directory
9077 <file>/usr/share/doc/<var>package</var></file>, where
9078 <var>package</var> is the name of the package, and
9079 compressed with <tt>gzip -9</tt> unless it is small.
9083 If a package comes with large amounts of documentation which
9084 many users of the package will not require you should create
9085 a separate binary package to contain it, so that it does not
9086 take up disk space on the machines of users who do not need
9087 or want it installed.</p>
9090 It is often a good idea to put text information files
9091 (<file>README</file>s, changelogs, and so forth) that come with
9092 the source package in <file>/usr/share/doc/<var>package</var></file>
9093 in the binary package. However, you don't need to install
9094 the instructions for building and installing the package, of
9098 Packages must not require the existence of any files in
9099 <file>/usr/share/doc/</file> in order to function
9101 The system administrator should be able to
9102 delete files in <file>/usr/share/doc/</file> without causing
9103 any programs to break.
9105 Any files that are referenced by programs but are also
9106 useful as stand alone documentation should be installed under
9107 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9108 <file>/usr/share/doc/<var>package</var></file>.
9112 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9113 link to another directory in <file>/usr/share/doc</file> only if
9114 the two packages both come from the same source and the
9115 first package Depends on the second.<footnote>
9117 Please note that this does not override the section on
9118 changelog files below, so the file
9119 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9120 must refer to the changelog for the current version of
9121 <var>package</var> in question. In practice, this means
9122 that the sources of the target and the destination of the
9123 symlink must be the same (same source package and
9130 Former Debian releases placed all additional documentation
9131 in <file>/usr/doc/<var>package</var></file>. This has been
9132 changed to <file>/usr/share/doc/<var>package</var></file>,
9133 and packages must not put documentation in the directory
9134 <file>/usr/doc/<var>package</var></file>. <footnote>
9135 At this phase of the transition, we no longer require a
9136 symbolic link in <file>/usr/doc/</file>. At a later point,
9137 policy shall change to make the symbolic links a bug.
9143 <heading>Preferred documentation formats</heading>
9146 The unification of Debian documentation is being carried out
9150 If your package comes with extensive documentation in a
9151 markup format that can be converted to various other formats
9152 you should if possible ship HTML versions in a binary
9153 package, in the directory
9154 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9155 its subdirectories.<footnote>
9156 The rationale: The important thing here is that HTML
9157 docs should be available in <em>some</em> package, not
9158 necessarily in the main binary package.
9163 Other formats such as PostScript may be provided at the
9164 package maintainer's discretion.
9168 <sect id="copyrightfile">
9169 <heading>Copyright information</heading>
9172 Every package must be accompanied by a verbatim copy of its
9173 copyright and distribution license in the file
9174 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9175 file must neither be compressed nor be a symbolic link.
9179 In addition, the copyright file must say where the upstream
9180 sources (if any) were obtained. It should name the original
9181 authors of the package and the Debian maintainer(s) who were
9182 involved with its creation.
9186 Packages in the <em>contrib</em> or <em>non-free</em> archive
9187 areas should state in the copyright file that the package is not
9188 part of the Debian GNU/Linux distribution and briefly explain
9193 A copy of the file which will be installed in
9194 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9195 be in <file>debian/copyright</file> in the source package.
9199 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9200 link to another directory in <file>/usr/share/doc</file> only if
9201 the two packages both come from the same source and the
9202 first package Depends on the second. These rules are
9203 important because copyrights must be extractable by
9208 Packages distributed under the UCB BSD license, the Apache
9209 license (version 2.0), the Artistic license, the GNU GPL
9210 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9211 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9212 files under <file>/usr/share/common-licenses</file>,<footnote>
9215 <file>/usr/share/common-licenses/BSD</file>,
9216 <file>/usr/share/common-licenses/Apache-2.0</file>,
9217 <file>/usr/share/common-licenses/Artistic</file>,
9218 <file>/usr/share/common-licenses/GPL-2</file>,
9219 <file>/usr/share/common-licenses/GPL-3</file>,
9220 <file>/usr/share/common-licenses/LGPL-2</file>,
9221 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9222 <file>/usr/share/common-licenses/LGPL-3</file>,
9223 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9224 <file>/usr/share/common-licenses/GFDL-1.3</file>
9227 </footnote> rather than quoting them in the copyright
9232 You should not use the copyright file as a general <file>README</file>
9233 file. If your package has such a file it should be
9234 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9235 <file>README.Debian</file> or some other appropriate place.</p>
9239 <heading>Examples</heading>
9242 Any examples (configurations, source files, whatever),
9243 should be installed in a directory
9244 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9245 files should not be referenced by any program: they're there
9246 for the benefit of the system administrator and users as
9247 documentation only. Architecture-specific example files
9248 should be installed in a directory
9249 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9251 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9252 latter directory itself may be a symbolic link to the
9257 If the purpose of a package is to provide examples, then the
9258 example files may be installed into
9259 <file>/usr/share/doc/<var>package</var></file>.
9263 <sect id="changelogs">
9264 <heading>Changelog files</heading>
9267 Packages that are not Debian-native must contain a
9268 compressed copy of the <file>debian/changelog</file> file from
9269 the Debian source tree in
9270 <file>/usr/share/doc/<var>package</var></file> with the name
9271 <file>changelog.Debian.gz</file>.
9275 If an upstream changelog is available, it should be accessible as
9276 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9277 plain text. If the upstream changelog is distributed in
9278 HTML, it should be made available in that form as
9279 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9280 and a plain text <file>changelog.gz</file> should be generated
9281 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9282 the upstream changelog files do not already conform to this
9283 naming convention, then this may be achieved either by
9284 renaming the files, or by adding a symbolic link, at the
9285 maintainer's discretion.<footnote>
9286 Rationale: People should not have to look in places for
9287 upstream changelogs merely because they are given
9288 different names or are distributed in HTML format.
9293 All of these files should be installed compressed using
9294 <tt>gzip -9</tt>, as they will become large with time even
9295 if they start out small.
9299 If the package has only one changelog which is used both as
9300 the Debian changelog and the upstream one because there is
9301 no separate upstream maintainer then that changelog should
9302 usually be installed as
9303 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9304 there is a separate upstream maintainer, but no upstream
9305 changelog, then the Debian changelog should still be called
9306 <file>changelog.Debian.gz</file>.
9310 For details about the format and contents of the Debian
9311 changelog file, please see <ref id="dpkgchangelog">.
9316 <appendix id="pkg-scope">
9317 <heading>Introduction and scope of these appendices</heading>
9320 These appendices are taken essentially verbatim from the
9321 now-deprecated Packaging Manual, version 3.2.1.0. They are
9322 the chapters which are likely to be of use to package
9323 maintainers and which have not already been included in the
9324 policy document itself. Most of these sections are very likely
9325 not relevant to policy; they should be treated as
9326 documentation for the packaging system. Please note that these
9327 appendices are included for convenience, and for historical
9328 reasons: they used to be part of policy package, and they have
9329 not yet been incorporated into dpkg documentation. However,
9330 they still have value, and hence they are presented here.
9334 They have not yet been checked to ensure that they are
9335 compatible with the contents of policy, and if there are any
9336 contradictions, the version in the main policy document takes
9337 precedence. The remaining chapters of the old Packaging
9338 Manual have also not been read in detail to ensure that there
9339 are not parts which have been left out. Both of these will be
9344 Certain parts of the Packaging manual were integrated into the
9345 Policy Manual proper, and removed from the appendices. Links
9346 have been placed from the old locations to the new ones.
9350 <prgn>dpkg</prgn> is a suite of programs for creating binary
9351 package files and installing and removing them on Unix
9353 <prgn>dpkg</prgn> is targeted primarily at Debian
9354 GNU/Linux, but may work on or be ported to other
9360 The binary packages are designed for the management of
9361 installed executable programs (usually compiled binaries) and
9362 their associated data, though source code examples and
9363 documentation are provided as part of some packages.</p>
9366 This manual describes the technical aspects of creating Debian
9367 binary packages (<file>.deb</file> files). It documents the
9368 behavior of the package management programs
9369 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9370 they interact with packages.</p>
9373 It also documents the interaction between
9374 <prgn>dselect</prgn>'s core and the access method scripts it
9375 uses to actually install the selected packages, and describes
9376 how to create a new access method.</p>
9379 This manual does not go into detail about the options and
9380 usage of the package building and installation tools. It
9381 should therefore be read in conjunction with those programs'
9386 The utility programs which are provided with <prgn>dpkg</prgn>
9387 for managing various system configuration and similar issues,
9388 such as <prgn>update-rc.d</prgn> and
9389 <prgn>install-info</prgn>, are not described in detail here -
9390 please see their man pages.
9394 It is assumed that the reader is reasonably familiar with the
9395 <prgn>dpkg</prgn> System Administrators' manual.
9396 Unfortunately this manual does not yet exist.
9400 The Debian version of the FSF's GNU hello program is provided
9401 as an example for people wishing to create Debian
9402 packages. The Debian <prgn>debmake</prgn> package is
9403 recommended as a very helpful tool in creating and maintaining
9404 Debian packages. However, while the tools and examples are
9405 helpful, they do not replace the need to read and follow the
9406 Policy and Programmer's Manual.</p>
9409 <appendix id="pkg-binarypkg">
9410 <heading>Binary packages (from old Packaging Manual)</heading>
9413 The binary package has two main sections. The first part
9414 consists of various control information files and scripts used
9415 by <prgn>dpkg</prgn> when installing and removing. See <ref
9416 id="pkg-controlarea">.
9420 The second part is an archive containing the files and
9421 directories to be installed.
9425 In the future binary packages may also contain other
9426 components, such as checksums and digital signatures. The
9427 format for the archive is described in full in the
9428 <file>deb(5)</file> man page.
9432 <sect id="pkg-bincreating"><heading>Creating package files -
9433 <prgn>dpkg-deb</prgn>
9437 All manipulation of binary package files is done by
9438 <prgn>dpkg-deb</prgn>; it's the only program that has
9439 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9440 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9441 will spot that the options requested are appropriate to
9442 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9447 In order to create a binary package you must make a
9448 directory tree which contains all the files and directories
9449 you want to have in the file system data part of the package.
9450 In Debian-format source packages this directory is usually
9451 <file>debian/tmp</file>, relative to the top of the package's
9456 They should have the locations (relative to the root of the
9457 directory tree you're constructing) ownerships and
9458 permissions which you want them to have on the system when
9463 With current versions of <prgn>dpkg</prgn> the uid/username
9464 and gid/groupname mappings for the users and groups being
9465 used should be the same on the system where the package is
9466 built and the one where it is installed.
9470 You need to add one special directory to the root of the
9471 miniature file system tree you're creating:
9472 <prgn>DEBIAN</prgn>. It should contain the control
9473 information files, notably the binary package control file
9474 (see <ref id="pkg-controlfile">).
9478 The <prgn>DEBIAN</prgn> directory will not appear in the
9479 file system archive of the package, and so won't be installed
9480 by <prgn>dpkg</prgn> when the package is installed.
9484 When you've prepared the package, you should invoke:
9486 dpkg --build <var>directory</var>
9491 This will build the package in
9492 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9493 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9494 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9499 See the man page <manref name="dpkg-deb" section="8"> for details of how
9500 to examine the contents of this newly-created file. You may find the
9501 output of following commands enlightening:
9503 dpkg-deb --info <var>filename</var>.deb
9504 dpkg-deb --contents <var>filename</var>.deb
9505 dpkg --contents <var>filename</var>.deb
9507 To view the copyright file for a package you could use this command:
9509 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9514 <sect id="pkg-controlarea">
9515 <heading>Package control information files</heading>
9518 The control information portion of a binary package is a
9519 collection of files with names known to <prgn>dpkg</prgn>.
9520 It will treat the contents of these files specially - some
9521 of them contain information used by <prgn>dpkg</prgn> when
9522 installing or removing the package; others are scripts which
9523 the package maintainer wants <prgn>dpkg</prgn> to run.
9527 It is possible to put other files in the package control
9528 area, but this is not generally a good idea (though they
9529 will largely be ignored).
9533 Here is a brief list of the control info files supported by
9534 <prgn>dpkg</prgn> and a summary of what they're used for.
9539 <tag><tt>control</tt>
9542 This is the key description file used by
9543 <prgn>dpkg</prgn>. It specifies the package's name
9544 and version, gives its description for the user,
9545 states its relationships with other packages, and so
9546 forth. See <ref id="sourcecontrolfiles"> and
9547 <ref id="binarycontrolfiles">.
9551 It is usually generated automatically from information
9552 in the source package by the
9553 <prgn>dpkg-gencontrol</prgn> program, and with
9554 assistance from <prgn>dpkg-shlibdeps</prgn>.
9555 See <ref id="pkg-sourcetools">.
9559 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9564 These are executable files (usually scripts) which
9565 <prgn>dpkg</prgn> runs during installation, upgrade
9566 and removal of packages. They allow the package to
9567 deal with matters which are particular to that package
9568 or require more complicated processing than that
9569 provided by <prgn>dpkg</prgn>. Details of when and
9570 how they are called are in <ref id="maintainerscripts">.
9574 It is very important to make these scripts idempotent.
9575 See <ref id="idempotency">.
9579 The maintainer scripts are guaranteed to run with a
9580 controlling terminal and can interact with the user.
9581 See <ref id="controllingterminal">.
9585 <tag><tt>conffiles</tt>
9588 This file contains a list of configuration files which
9589 are to be handled automatically by <prgn>dpkg</prgn>
9590 (see <ref id="pkg-conffiles">). Note that not necessarily
9591 every configuration file should be listed here.
9594 <tag><tt>shlibs</tt>
9597 This file contains a list of the shared libraries
9598 supplied by the package, with dependency details for
9599 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9600 when it determines what dependencies are required in a
9601 package control file. The <tt>shlibs</tt> file format
9602 is described on <ref id="shlibs">.
9607 <sect id="pkg-controlfile">
9608 <heading>The main control information file: <tt>control</tt></heading>
9611 The most important control information file used by
9612 <prgn>dpkg</prgn> when it installs a package is
9613 <tt>control</tt>. It contains all the package's "vital
9618 The binary package control files of packages built from
9619 Debian sources are made by a special tool,
9620 <prgn>dpkg-gencontrol</prgn>, which reads
9621 <file>debian/control</file> and <file>debian/changelog</file> to
9622 find the information it needs. See <ref id="pkg-sourcepkg"> for
9627 The fields in binary package control files are listed in
9628 <ref id="binarycontrolfiles">.
9632 A description of the syntax of control files and the purpose
9633 of the fields is available in <ref id="controlfields">.
9638 <heading>Time Stamps</heading>
9641 See <ref id="timestamps">.
9646 <appendix id="pkg-sourcepkg">
9647 <heading>Source packages (from old Packaging Manual) </heading>
9650 The Debian binary packages in the distribution are generated
9651 from Debian sources, which are in a special format to assist
9652 the easy and automatic building of binaries.
9655 <sect id="pkg-sourcetools">
9656 <heading>Tools for processing source packages</heading>
9659 Various tools are provided for manipulating source packages;
9660 they pack and unpack sources and help build of binary
9661 packages and help manage the distribution of new versions.
9665 They are introduced and typical uses described here; see
9666 <manref name="dpkg-source" section="1"> for full
9667 documentation about their arguments and operation.
9671 For examples of how to construct a Debian source package,
9672 and how to use those utilities that are used by Debian
9673 source packages, please see the <prgn>hello</prgn> example
9677 <sect1 id="pkg-dpkg-source">
9679 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9684 This program is frequently used by hand, and is also
9685 called from package-independent automated building scripts
9686 such as <prgn>dpkg-buildpackage</prgn>.
9690 To unpack a package it is typically invoked with
9692 dpkg-source -x <var>.../path/to/filename</var>.dsc
9697 with the <file><var>filename</var>.tar.gz</file> and
9698 <file><var>filename</var>.diff.gz</file> (if applicable) in
9699 the same directory. It unpacks into
9700 <file><var>package</var>-<var>version</var></file>, and if
9702 <file><var>package</var>-<var>version</var>.orig</file>, in
9703 the current directory.
9707 To create a packed source archive it is typically invoked:
9709 dpkg-source -b <var>package</var>-<var>version</var>
9714 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9715 <file>.diff.gz</file> (if appropriate) in the current
9716 directory. <prgn>dpkg-source</prgn> does not clean the
9717 source tree first - this must be done separately if it is
9722 See also <ref id="pkg-sourcearchives">.</p>
9726 <sect1 id="pkg-dpkg-buildpackage">
9728 <prgn>dpkg-buildpackage</prgn> - overall package-building
9733 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9734 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9735 targets <tt>clean</tt>, <tt>build</tt> and
9736 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9737 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9738 source and binary package upload.
9742 It is usually invoked by hand from the top level of the
9743 built or unbuilt source directory. It may be invoked with
9744 no arguments; useful arguments include:
9745 <taglist compact="compact">
9746 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9749 Do not sign the <tt>.changes</tt> file or the
9750 source package <tt>.dsc</tt> file, respectively.</p>
9752 <tag><tt>-p<var>sign-command</var></tt></tag>
9755 Invoke <var>sign-command</var> instead of finding
9756 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9757 <var>sign-command</var> must behave just like
9758 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9760 <tag><tt>-r<var>root-command</var></tt></tag>
9763 When root privilege is required, invoke the command
9764 <var>root-command</var>. <var>root-command</var>
9765 should invoke its first argument as a command, from
9766 the <prgn>PATH</prgn> if necessary, and pass its
9767 second and subsequent arguments to the command it
9768 calls. If no <var>root-command</var> is supplied
9769 then <var>dpkg-buildpackage</var> will take no
9770 special action to gain root privilege, so that for
9771 most packages it will have to be invoked as root to
9774 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9777 Two types of binary-only build and upload - see
9778 <manref name="dpkg-source" section="1">.
9785 <sect1 id="pkg-dpkg-gencontrol">
9787 <prgn>dpkg-gencontrol</prgn> - generates binary package
9792 This program is usually called from <file>debian/rules</file>
9793 (see <ref id="pkg-sourcetree">) in the top level of the source
9798 This is usually done just before the files and directories in the
9799 temporary directory tree where the package is being built have their
9800 permissions and ownerships set and the package is constructed using
9801 <prgn>dpkg-deb/</prgn>
9803 This is so that the control file which is produced has
9804 the right permissions
9809 <prgn>dpkg-gencontrol</prgn> must be called after all the
9810 files which are to go into the package have been placed in
9811 the temporary build directory, so that its calculation of
9812 the installed size of a package is correct.
9816 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9817 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9818 variable substitutions created by
9819 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9824 For a package which generates only one binary package, and
9825 which builds it in <file>debian/tmp</file> relative to the top
9826 of the source package, it is usually sufficient to call
9827 <prgn>dpkg-gencontrol</prgn>.
9831 Sources which build several binaries will typically need
9834 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9835 </example> The <tt>-P</tt> tells
9836 <prgn>dpkg-gencontrol</prgn> that the package is being
9837 built in a non-default directory, and the <tt>-p</tt>
9838 tells it which package's control file should be generated.
9842 <prgn>dpkg-gencontrol</prgn> also adds information to the
9843 list of files in <file>debian/files</file>, for the benefit of
9844 (for example) a future invocation of
9845 <prgn>dpkg-genchanges</prgn>.</p>
9848 <sect1 id="pkg-dpkg-shlibdeps">
9850 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9855 This program is usually called from <file>debian/rules</file>
9856 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9857 id="pkg-sourcetree">), in the top level of the source tree.
9861 Its arguments are executables and shared libraries
9864 They may be specified either in the locations in the
9865 source tree where they are created or in the locations
9866 in the temporary build tree where they are installed
9867 prior to binary package creation.
9869 </footnote> for which shared library dependencies should
9870 be included in the binary package's control file.
9874 If some of the found shared libraries should only
9875 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9876 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9877 by using the <tt>-d<var>dependency-field</var></tt> option
9878 before those executable(s). (Each <tt>-d</tt> option
9879 takes effect until the next <tt>-d</tt>.)
9883 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9884 output control file to be modified. Instead by default it
9885 adds to the <file>debian/substvars</file> file variable
9886 settings like <tt>shlibs:Depends</tt>. These variable
9887 settings must be referenced in dependency fields in the
9888 appropriate per-binary-package sections of the source
9893 For example, a package that generates an essential part
9894 which requires dependencies, and optional parts that
9895 which only require a recommendation, would separate those
9896 two sets of dependencies into two different fields.<footnote>
9897 At the time of writing, an example for this was the
9898 <package/xmms/ package, with Depends used for the xmms
9899 executable, Recommends for the plug-ins and Suggests for
9900 even more optional features provided by unzip.
9902 It can say in its <file>debian/rules</file>:
9904 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9905 -dRecommends <var>optionalpart anotheroptionalpart</var>
9907 and then in its main control file <file>debian/control</file>:
9910 Depends: ${shlibs:Depends}
9911 Recommends: ${shlibs:Recommends}
9917 Sources which produce several binary packages with
9918 different shared library dependency requirements can use
9919 the <tt>-p<var>varnameprefix</var></tt> option to override
9920 the default <tt>shlibs:</tt> prefix (one invocation of
9921 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9922 They can thus produce several sets of dependency
9923 variables, each of the form
9924 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9925 which can be referred to in the appropriate parts of the
9926 binary package control files.
9931 <sect1 id="pkg-dpkg-distaddfile">
9933 <prgn>dpkg-distaddfile</prgn> - adds a file to
9934 <file>debian/files</file>
9938 Some packages' uploads need to include files other than
9939 the source and binary package files.
9943 <prgn>dpkg-distaddfile</prgn> adds a file to the
9944 <file>debian/files</file> file so that it will be included in
9945 the <file>.changes</file> file when
9946 <prgn>dpkg-genchanges</prgn> is run.
9950 It is usually invoked from the <tt>binary</tt> target of
9951 <file>debian/rules</file>:
9953 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9955 The <var>filename</var> is relative to the directory where
9956 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9957 is usually the directory above the top level of the source
9958 tree. The <file>debian/rules</file> target should put the
9959 file there just before or just after calling
9960 <prgn>dpkg-distaddfile</prgn>.
9964 The <var>section</var> and <var>priority</var> are passed
9965 unchanged into the resulting <file>.changes</file> file.
9970 <sect1 id="pkg-dpkg-genchanges">
9972 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9977 This program is usually called by package-independent
9978 automatic building scripts such as
9979 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9984 It is usually called in the top level of a built source
9985 tree, and when invoked with no arguments will print out a
9986 straightforward <file>.changes</file> file based on the
9987 information in the source package's changelog and control
9988 file and the binary and source packages which should have
9994 <sect1 id="pkg-dpkg-parsechangelog">
9996 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9997 representation of a changelog
10001 This program is used internally by
10002 <prgn>dpkg-source</prgn> et al. It may also occasionally
10003 be useful in <file>debian/rules</file> and elsewhere. It
10004 parses a changelog, <file>debian/changelog</file> by default,
10005 and prints a control-file format representation of the
10006 information in it to standard output.
10010 <sect1 id="pkg-dpkg-architecture">
10012 <prgn>dpkg-architecture</prgn> - information about the build and
10017 This program can be used manually, but is also invoked by
10018 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10019 environment or make variables which specify the build and host
10020 architecture for the package building process.
10025 <sect id="pkg-sourcetree">
10026 <heading>The Debianised source tree</heading>
10029 The source archive scheme described later is intended to
10030 allow a Debianised source tree with some associated control
10031 information to be reproduced and transported easily. The
10032 Debianised source tree is a version of the original program
10033 with certain files added for the benefit of the
10034 Debianisation process, and with any other changes required
10035 made to the rest of the source code and installation
10040 The extra files created for Debian are in the subdirectory
10041 <file>debian</file> of the top level of the Debianised source
10042 tree. They are described below.
10045 <sect1 id="pkg-debianrules">
10046 <heading><file>debian/rules</file> - the main building script</heading>
10049 See <ref id="debianrules">.
10054 <sect1 id="pkg-dpkgchangelog">
10055 <heading><file>debian/changelog</file></heading>
10058 See <ref id="dpkgchangelog">.
10061 <sect2><heading>Defining alternative changelog formats
10065 It is possible to use a different format to the standard
10066 one, by providing a parser for the format you wish to
10071 In order to have <tt>dpkg-parsechangelog</tt> run your
10072 parser, you must include a line within the last 40 lines
10073 of your file matching the Perl regular expression:
10074 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
10075 parentheses should be the name of the format. For
10076 example, you might say:
10078 @@@ changelog-format: joebloggs @@@
10080 Changelog format names are non-empty strings of alphanumerics.
10084 If such a line exists then <tt>dpkg-parsechangelog</tt>
10085 will look for the parser as
10086 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
10088 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
10089 it is an error for it not to find it, or for it not to
10090 be an executable program. The default changelog format
10091 is <tt>dpkg</tt>, and a parser for it is provided with
10092 the <tt>dpkg</tt> package.
10096 The parser will be invoked with the changelog open on
10097 standard input at the start of the file. It should read
10098 the file (it may seek if it wishes) to determine the
10099 information required and return the parsed information
10100 to standard output in the form of a series of control
10101 fields in the standard format. By default it should
10102 return information about only the most recent version in
10103 the changelog; it should accept a
10104 <tt>-v<var>version</var></tt> option to return changes
10105 information from all versions present <em>strictly
10106 after</em> <var>version</var>, and it should then be an
10107 error for <var>version</var> not to be present in the
10113 <list compact="compact">
10114 <item><qref id="f-Source"><tt>Source</tt></qref></item>
10115 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
10116 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
10117 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
10118 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
10119 <item><qref id="f-Date"><tt>Date</tt></qref></item>
10120 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
10125 If several versions are being returned (due to the use
10126 of <tt>-v</tt>), the urgency value should be of the
10127 highest urgency code listed at the start of any of the
10128 versions requested followed by the concatenated
10129 (space-separated) comments from all the versions
10130 requested; the maintainer, version, distribution and
10131 date should always be from the most recent version.
10135 For the format of the <tt>Changes</tt> field see
10136 <ref id="f-Changes">.
10140 If the changelog format which is being parsed always or
10141 almost always leaves a blank line between individual
10142 change notes these blank lines should be stripped out,
10143 so as to make the resulting output compact.
10147 If the changelog format does not contain date or package
10148 name information this information should be omitted from
10149 the output. The parser should not attempt to synthesize
10150 it or find it from other sources.
10154 If the changelog does not have the expected format the
10155 parser should exit with a nonzero exit status, rather
10156 than trying to muddle through and possibly generating
10161 A changelog parser may not interact with the user at
10167 <sect1 id="pkg-srcsubstvars">
10168 <heading><file>debian/substvars</file> and variable substitutions</heading>
10171 See <ref id="substvars">.
10177 <heading><file>debian/files</file></heading>
10180 See <ref id="debianfiles">.
10184 <sect1><heading><file>debian/tmp</file>
10188 This is the canonical temporary location for the
10189 construction of binary packages by the <tt>binary</tt>
10190 target. The directory <file>tmp</file> serves as the root of
10191 the file system tree as it is being constructed (for
10192 example, by using the package's upstream makefiles install
10193 targets and redirecting the output there), and it also
10194 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10195 id="pkg-bincreating">.
10199 If several binary packages are generated from the same
10200 source tree it is usual to use several
10201 <file>debian/tmp<var>something</var></file> directories, for
10202 example <file>tmp-a</file> or <file>tmp-doc</file>.
10206 Whatever <file>tmp</file> directories are created and used by
10207 <tt>binary</tt> must of course be removed by the
10208 <tt>clean</tt> target.</p></sect1>
10212 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10216 As it exists on the FTP site, a Debian source package
10217 consists of three related files. You must have the right
10218 versions of all three to be able to use them.
10223 <tag>Debian source control file - <tt>.dsc</tt></tag>
10225 This file is a control file used by <prgn>dpkg-source</prgn>
10226 to extract a source package.
10227 See <ref id="debiansourcecontrolfiles">.
10231 Original source archive -
10233 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10239 This is a compressed (with <tt>gzip -9</tt>)
10240 <prgn>tar</prgn> file containing the source code from
10241 the upstream authors of the program.
10246 Debianisation diff -
10248 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10254 This is a unified context diff (<tt>diff -u</tt>)
10255 giving the changes which are required to turn the
10256 original source into the Debian source. These changes
10257 may only include editing and creating plain files.
10258 The permissions of files, the targets of symbolic
10259 links and the characteristics of special files or
10260 pipes may not be changed and no files may be removed
10265 All the directories in the diff must exist, except the
10266 <file>debian</file> subdirectory of the top of the source
10267 tree, which will be created by
10268 <prgn>dpkg-source</prgn> if necessary when unpacking.
10272 The <prgn>dpkg-source</prgn> program will
10273 automatically make the <file>debian/rules</file> file
10274 executable (see below).</p></item>
10279 If there is no original source code - for example, if the
10280 package is specially prepared for Debian or the Debian
10281 maintainer is the same as the upstream maintainer - the
10282 format is slightly different: then there is no diff, and the
10284 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10285 and preferably contains a directory named
10286 <file><var>package</var>-<var>version</var></file>.
10291 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10294 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10295 Debian source package. However, if it is not available it
10296 is possible to unpack a Debian source archive as follows:
10297 <enumlist compact="compact">
10300 Untar the tarfile, which will create a <file>.orig</file>
10304 <p>Rename the <file>.orig</file> directory to
10305 <file><var>package</var>-<var>version</var></file>.</p>
10309 Create the subdirectory <file>debian</file> at the top of
10310 the source tree.</p>
10312 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10314 <item><p>Untar the tarfile again if you want a copy of the original
10315 source code alongside the Debianised version.</p>
10320 It is not possible to generate a valid Debian source archive
10321 without using <prgn>dpkg-source</prgn>. In particular,
10322 attempting to use <prgn>diff</prgn> directly to generate the
10323 <file>.diff.gz</file> file will not work.
10327 <heading>Restrictions on objects in source packages</heading>
10330 The source package may not contain any hard links
10332 This is not currently detected when building source
10333 packages, but only when extracting
10337 Hard links may be permitted at some point in the
10338 future, but would require a fair amount of
10340 </footnote>, device special files, sockets or setuid or
10343 Setgid directories are allowed.
10348 The source packaging tools manage the changes between the
10349 original and Debianised source using <prgn>diff</prgn> and
10350 <prgn>patch</prgn>. Turning the original source tree as
10351 included in the <file>.orig.tar.gz</file> into the debianised
10352 source must not involve any changes which cannot be
10353 handled by these tools. Problematic changes which cause
10354 <prgn>dpkg-source</prgn> to halt with an error when
10355 building the source package are:
10356 <list compact="compact">
10357 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10359 <item><p>Changing the targets of symbolic links.</p>
10361 <item><p>Creating directories, other than <file>debian</file>.</p>
10363 <item><p>Changes to the contents of binary files.</p></item>
10364 </list> Changes which cause <prgn>dpkg-source</prgn> to
10365 print a warning but continue anyway are:
10366 <list compact="compact">
10369 Removing files, directories or symlinks.
10371 Renaming a file is not treated specially - it is
10372 seen as the removal of the old file (which
10373 generates a warning, but is otherwise ignored),
10374 and the creation of the new one.
10380 Changed text files which are missing the usual final
10381 newline (either in the original or the modified
10386 Changes which are not represented, but which are not detected by
10387 <prgn>dpkg-source</prgn>, are:
10388 <list compact="compact">
10389 <item><p>Changing the permissions of files (other than
10390 <file>debian/rules</file>) and directories.</p></item>
10395 The <file>debian</file> directory and <file>debian/rules</file>
10396 are handled specially by <prgn>dpkg-source</prgn> - before
10397 applying the changes it will create the <file>debian</file>
10398 directory, and afterwards it will make
10399 <file>debian/rules</file> world-executable.
10405 <appendix id="pkg-controlfields">
10406 <heading>Control files and their fields (from old Packaging Manual)</heading>
10409 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10410 data in a common format, known as control files. Binary and
10411 source packages have control data as do the <file>.changes</file>
10412 files which control the installation of uploaded files, and
10413 <prgn>dpkg</prgn>'s internal databases are in a similar
10418 <heading>Syntax of control files</heading>
10421 See <ref id="controlsyntax">.
10425 It is important to note that there are several fields which
10426 are optional as far as <prgn>dpkg</prgn> and the related
10427 tools are concerned, but which must appear in every Debian
10428 package, or whose omission may cause problems.
10433 <heading>List of fields</heading>
10436 See <ref id="controlfieldslist">.
10440 This section now contains only the fields that didn't belong
10441 to the Policy manual.
10444 <sect1 id="pkg-f-Filename">
10445 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10448 These fields in <tt>Packages</tt> files give the
10449 filename(s) of (the parts of) a package in the
10450 distribution directories, relative to the root of the
10451 Debian hierarchy. If the package has been split into
10452 several parts the parts are all listed in order, separated
10457 <sect1 id="pkg-f-Size">
10458 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10461 These fields in <file>Packages</file> files give the size (in
10462 bytes, expressed in decimal) and MD5 checksum of the
10463 file(s) which make(s) up a binary package in the
10464 distribution. If the package is split into several parts
10465 the values for the parts are listed in order, separated by
10470 <sect1 id="pkg-f-Status">
10471 <heading><tt>Status</tt></heading>
10474 This field in <prgn>dpkg</prgn>'s status file records
10475 whether the user wants a package installed, removed or
10476 left alone, whether it is broken (requiring
10477 re-installation) or not and what its current state on the
10478 system is. Each of these pieces of information is a
10483 <sect1 id="pkg-f-Config-Version">
10484 <heading><tt>Config-Version</tt></heading>
10487 If a package is not installed or not configured, this
10488 field in <prgn>dpkg</prgn>'s status file records the last
10489 version of the package which was successfully
10494 <sect1 id="pkg-f-Conffiles">
10495 <heading><tt>Conffiles</tt></heading>
10498 This field in <prgn>dpkg</prgn>'s status file contains
10499 information about the automatically-managed configuration
10500 files held by a package. This field should <em>not</em>
10501 appear anywhere in a package!
10506 <heading>Obsolete fields</heading>
10509 These are still recognized by <prgn>dpkg</prgn> but should
10510 not appear anywhere any more.
10512 <taglist compact="compact">
10514 <tag><tt>Revision</tt></tag>
10515 <tag><tt>Package-Revision</tt></tag>
10516 <tag><tt>Package_Revision</tt></tag>
10518 The Debian revision part of the package version was
10519 at one point in a separate control file field. This
10520 field went through several names.
10523 <tag><tt>Recommended</tt></tag>
10524 <item>Old name for <tt>Recommends</tt>.</item>
10526 <tag><tt>Optional</tt></tag>
10527 <item>Old name for <tt>Suggests</tt>.</item>
10529 <tag><tt>Class</tt></tag>
10530 <item>Old name for <tt>Priority</tt>.</item>
10539 <appendix id="pkg-conffiles">
10540 <heading>Configuration file handling (from old Packaging Manual)</heading>
10543 <prgn>dpkg</prgn> can do a certain amount of automatic
10544 handling of package configuration files.
10548 Whether this mechanism is appropriate depends on a number of
10549 factors, but basically there are two approaches to any
10550 particular configuration file.
10554 The easy method is to ship a best-effort configuration in the
10555 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10556 handle updates. If the user is unlikely to want to edit the
10557 file, but you need them to be able to without losing their
10558 changes, and a new package with a changed version of the file
10559 is only released infrequently, this is a good approach.
10563 The hard method is to build the configuration file from
10564 scratch in the <prgn>postinst</prgn> script, and to take the
10565 responsibility for fixing any mistakes made in earlier
10566 versions of the package automatically. This will be
10567 appropriate if the file is likely to need to be different on
10571 <sect><heading>Automatic handling of configuration files by
10576 A package may contain a control area file called
10577 <tt>conffiles</tt>. This file should be a list of filenames
10578 of configuration files needing automatic handling, separated
10579 by newlines. The filenames should be absolute pathnames,
10580 and the files referred to should actually exist in the
10585 When a package is upgraded <prgn>dpkg</prgn> will process
10586 the configuration files during the configuration stage,
10587 shortly before it runs the package's <prgn>postinst</prgn>
10592 For each file it checks to see whether the version of the
10593 file included in the package is the same as the one that was
10594 included in the last version of the package (the one that is
10595 being upgraded from); it also compares the version currently
10596 installed on the system with the one shipped with the last
10601 If neither the user nor the package maintainer has changed
10602 the file, it is left alone. If one or the other has changed
10603 their version, then the changed version is preferred - i.e.,
10604 if the user edits their file, but the package maintainer
10605 doesn't ship a different version, the user's changes will
10606 stay, silently, but if the maintainer ships a new version
10607 and the user hasn't edited it the new version will be
10608 installed (with an informative message). If both have
10609 changed their version the user is prompted about the problem
10610 and must resolve the differences themselves.
10614 The comparisons are done by calculating the MD5 message
10615 digests of the files, and storing the MD5 of the file as it
10616 was included in the most recent version of the package.
10620 When a package is installed for the first time
10621 <prgn>dpkg</prgn> will install the file that comes with it,
10622 unless that would mean overwriting a file already on the
10627 However, note that <prgn>dpkg</prgn> will <em>not</em>
10628 replace a conffile that was removed by the user (or by a
10629 script). This is necessary because with some programs a
10630 missing file produces an effect hard or impossible to
10631 achieve in another way, so that a missing file needs to be
10632 kept that way if the user did it.
10636 Note that a package should <em>not</em> modify a
10637 <prgn>dpkg</prgn>-handled conffile in its maintainer
10638 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10639 the user confusing and possibly dangerous options for
10640 conffile update when the package is upgraded.</p>
10643 <sect><heading>Fully-featured maintainer script configuration
10648 For files which contain site-specific information such as
10649 the hostname and networking details and so forth, it is
10650 better to create the file in the package's
10651 <prgn>postinst</prgn> script.
10655 This will typically involve examining the state of the rest
10656 of the system to determine values and other information, and
10657 may involve prompting the user for some information which
10658 can't be obtained some other way.
10662 When using this method there are a couple of important
10663 issues which should be considered:
10667 If you discover a bug in the program which generates the
10668 configuration file, or if the format of the file changes
10669 from one version to the next, you will have to arrange for
10670 the postinst script to do something sensible - usually this
10671 will mean editing the installed configuration file to remove
10672 the problem or change the syntax. You will have to do this
10673 very carefully, since the user may have changed the file,
10674 perhaps to fix the very problem that your script is trying
10675 to deal with - you will have to detect these situations and
10676 deal with them correctly.
10680 If you do go down this route it's probably a good idea to
10681 make the program that generates the configuration file(s) a
10682 separate program in <file>/usr/sbin</file>, by convention called
10683 <file><var>package</var>config</file> and then run that if
10684 appropriate from the post-installation script. The
10685 <tt><var>package</var>config</tt> program should not
10686 unquestioningly overwrite an existing configuration - if its
10687 mode of operation is geared towards setting up a package for
10688 the first time (rather than any arbitrary reconfiguration
10689 later) you should have it check whether the configuration
10690 already exists, and require a <tt>--force</tt> flag to
10691 overwrite it.</p></sect>
10694 <appendix id="pkg-alternatives"><heading>Alternative versions of
10695 an interface - <prgn>update-alternatives</prgn> (from old
10700 When several packages all provide different versions of the
10701 same program or file it is useful to have the system select a
10702 default, but to allow the system administrator to change it
10703 and have their decisions respected.
10707 For example, there are several versions of the <prgn>vi</prgn>
10708 editor, and there is no reason to prevent all of them from
10709 being installed at once, each under their own name
10710 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10711 Nevertheless it is desirable to have the name <tt>vi</tt>
10712 refer to something, at least by default.
10716 If all the packages involved cooperate, this can be done with
10717 <prgn>update-alternatives</prgn>.
10721 Each package provides its own version under its own name, and
10722 calls <prgn>update-alternatives</prgn> in its postinst to
10723 register its version (and again in its prerm to deregister
10728 See the man page <manref name="update-alternatives"
10729 section="8"> for details.
10733 If <prgn>update-alternatives</prgn> does not seem appropriate
10734 you may wish to consider using diversions instead.</p>
10737 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10738 package's version of a file (from old Packaging Manual)
10742 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10743 when it reinstalls the package it belongs to, and to have it
10744 put the file from the package somewhere else instead.
10748 This can be used locally to override a package's version of a
10749 file, or by one package to override another's version (or
10750 provide a wrapper for it).
10754 Before deciding to use a diversion, read <ref
10755 id="pkg-alternatives"> to see if you really want a diversion
10756 rather than several alternative versions of a program.
10760 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10761 and updated by a special program <prgn>dpkg-divert</prgn>.
10762 Please see <manref name="dpkg-divert" section="8"> for full
10763 details of its operation.
10767 When a package wishes to divert a file from another, it should
10768 call <prgn>dpkg-divert</prgn> in its preinst to add the
10769 diversion and rename the existing file. For example,
10770 supposing that a <prgn>smailwrapper</prgn> package wishes to
10771 install a wrapper around <file>/usr/sbin/smail</file>:
10773 dpkg-divert --package smailwrapper --add --rename \
10774 --divert /usr/sbin/smail.real /usr/sbin/smail
10775 </example> The <tt>--package smailwrapper</tt> ensures that
10776 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10777 can bypass the diversion and get installed as the true version.
10778 It's safe to add the diversion unconditionally on upgrades since
10779 it will be left unchanged if it already exists, but
10780 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10781 message, make the command conditional on the version from which
10782 the package is being upgraded:
10784 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10785 dpkg-divert --package smailwrapper --add --rename \
10786 --divert /usr/sbin/smail.real /usr/sbin/smail
10788 </example> where <tt>1.0-2</tt> is the version at which the
10789 diversion was first added to the package. Running the command
10790 during abort-upgrade is pointless but harmless.
10794 The postrm has to do the reverse:
10796 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10797 dpkg-divert --package smailwrapper --remove --rename \
10798 --divert /usr/sbin/smail.real /usr/sbin/smail
10800 </example> If the diversion was added at a particular version, the
10801 postrm should also handle the failure case of upgrading from an
10802 older version (unless the older version is so old that direct
10803 upgrades are no longer supported):
10805 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10806 dpkg-divert --package smailwrapper --remove --rename \
10807 --divert /usr/sbin/smail.real /usr/sbin/smail
10809 </example> where <tt>1.02-2</tt> is the version at which the
10810 diversion was first added to the package. The postrm should not
10811 remove the diversion on upgrades both because there's no reason to
10812 remove the diversion only to immediately re-add it and since the
10813 postrm of the old package is run after unpacking so the removal of
10814 the diversion will fail.
10818 Do not attempt to divert a file which is vitally important for
10819 the system's operation - when using <prgn>dpkg-divert</prgn>
10820 there is a time, after it has been diverted but before
10821 <prgn>dpkg</prgn> has installed the new version, when the file
10822 does not exist.</p>
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