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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.
1732 Since an interactive <file>debian/rules</file> script makes it
1733 impossible to auto-compile that package and also makes it
1734 hard for other people to reproduce the same binary
1735 package, all <em>required targets</em> MUST be
1736 non-interactive. At a minimum, required targets are the
1737 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1738 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1739 <em>binary-indep</em>, and <em>build</em>. It also follows
1740 that any target that these targets depend on must also be
1745 The targets are as follows (required unless stated otherwise):
1747 <tag><tt>build</tt></tag>
1750 The <tt>build</tt> target should perform all the
1751 configuration and compilation of the package.
1752 If a package has an interactive pre-build
1753 configuration routine, the Debianized source package
1754 must either be built after this has taken place (so
1755 that the binary package can be built without rerunning
1756 the configuration) or the configuration routine
1757 modified to become non-interactive. (The latter is
1758 preferable if there are architecture-specific features
1759 detected by the configuration routine.)
1763 For some packages, notably ones where the same
1764 source tree is compiled in different ways to produce
1765 two binary packages, the <tt>build</tt> target
1766 does not make much sense. For these packages it is
1767 good enough to provide two (or more) targets
1768 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1769 for each of the ways of building the package, and a
1770 <tt>build</tt> target that does nothing. The
1771 <tt>binary</tt> target will have to build the
1772 package in each of the possible ways and make the
1773 binary package out of each.
1777 The <tt>build</tt> target must not do anything
1778 that might require root privilege.
1782 The <tt>build</tt> target may need to run the
1783 <tt>clean</tt> target first - see below.
1787 When a package has a configuration and build routine
1788 which takes a long time, or when the makefiles are
1789 poorly designed, or when <tt>build</tt> needs to
1790 run <tt>clean</tt> first, it is a good idea to
1791 <tt>touch build</tt> when the build process is
1792 complete. This will ensure that if <tt>debian/rules
1793 build</tt> is run again it will not rebuild the whole
1795 Another common way to do this is for <tt>build</tt>
1796 to depend on <prgn>build-stamp</prgn> and to do
1797 nothing else, and for the <prgn>build-stamp</prgn>
1798 target to do the building and to <tt>touch
1799 build-stamp</tt> on completion. This is
1800 especially useful if the build routine creates a
1801 file or directory called <tt>build</tt>; in such a
1802 case, <tt>build</tt> will need to be listed as
1803 a phony target (i.e., as a dependency of the
1804 <tt>.PHONY</tt> target). See the documentation of
1805 <prgn>make</prgn> for more information on phony
1811 <tag><tt>build-arch</tt> (optional),
1812 <tt>build-indep</tt> (optional)
1816 A package may also provide both of the targets
1817 <tt>build-arch</tt> and <tt>build-indep</tt>.
1818 The <tt>build-arch</tt> target, if provided, should
1819 perform all the configuration and compilation required
1820 for producing all architecture-dependant binary packages
1821 (those packages for which the body of the
1822 <tt>Architecture</tt> field in <tt>debian/control</tt>
1823 is not <tt>all</tt>).
1824 Similarly, the <tt>build-indep</tt> target, if
1825 provided, should perform all the configuration and
1826 compilation required for producing all
1827 architecture-independent binary packages
1828 (those packages for which the body of the
1829 <tt>Architecture</tt> field in <tt>debian/control</tt>
1831 The <tt>build</tt> target should depend on those of the
1832 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1833 are provided in the rules file.
1837 If one or both of the targets <tt>build-arch</tt> and
1838 <tt>build-indep</tt> are not provided, then invoking
1839 <file>debian/rules</file> with one of the not-provided
1840 targets as arguments should produce a exit status code
1841 of 2. Usually this is provided automatically by make
1842 if the target is missing.
1846 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1847 must not do anything that might require root privilege.
1851 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1852 <tt>binary-indep</tt>
1856 The <tt>binary</tt> target must be all that is
1857 necessary for the user to build the binary package(s)
1858 produced from this source package. It is
1859 split into two parts: <prgn>binary-arch</prgn> builds
1860 the binary packages which are specific to a particular
1861 architecture, and <tt>binary-indep</tt> builds
1862 those which are not.
1865 <tt>binary</tt> may be (and commonly is) a target with
1866 no commands which simply depends on
1867 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1870 Both <tt>binary-*</tt> targets should depend on the
1871 <tt>build</tt> target, or on the appropriate
1872 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1873 provided, so that the package is built if it has not
1874 been already. It should then create the relevant
1875 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1876 make their control files and <prgn>dpkg-deb</prgn> to
1877 build them and place them in the parent of the top
1882 Both the <tt>binary-arch</tt> and
1883 <tt>binary-indep</tt> targets <em>must</em> exist.
1884 If one of them has nothing to do (which will always be
1885 the case if the source generates only a single binary
1886 package, whether architecture-dependent or not), it
1887 must still exist and must always succeed.
1891 The <tt>binary</tt> targets must be invoked as
1893 The <prgn>fakeroot</prgn> package often allows one
1894 to build a package correctly even without being
1900 <tag><tt>clean</tt></tag>
1903 This must undo any effects that the <tt>build</tt>
1904 and <tt>binary</tt> targets may have had, except
1905 that it should leave alone any output files created in
1906 the parent directory by a run of a <tt>binary</tt>
1911 If a <tt>build</tt> file is touched at the end of
1912 the <tt>build</tt> target, as suggested above, it
1913 should be removed as the first action that
1914 <tt>clean</tt> performs, so that running
1915 <tt>build</tt> again after an interrupted
1916 <tt>clean</tt> doesn't think that everything is
1921 The <tt>clean</tt> target may need to be
1922 invoked as root if <tt>binary</tt> has been
1923 invoked since the last <tt>clean</tt>, or if
1924 <tt>build</tt> has been invoked as root (since
1925 <tt>build</tt> may create directories, for
1930 <tag><tt>get-orig-source</tt> (optional)</tag>
1933 This target fetches the most recent version of the
1934 original source package from a canonical archive site
1935 (via FTP or WWW, for example), does any necessary
1936 rearrangement to turn it into the original source
1937 tar file format described below, and leaves it in the
1942 This target may be invoked in any directory, and
1943 should take care to clean up any temporary files it
1948 This target is optional, but providing it if
1949 possible is a good idea.
1953 <tag><tt>patch</tt> (optional)</tag>
1956 This target performs whatever additional actions are
1957 required to make the source ready for editing (unpacking
1958 additional upstream archives, applying patches, etc.).
1959 It is recommended to be implemented for any package where
1960 <tt>dpkg-source -x</tt> does not result in source ready
1961 for additional modification. See
1962 <ref id="readmesource">.
1968 The <tt>build</tt>, <tt>binary</tt> and
1969 <tt>clean</tt> targets must be invoked with the current
1970 directory being the package's top-level directory.
1975 Additional targets may exist in <file>debian/rules</file>,
1976 either as published or undocumented interfaces or for the
1977 package's internal use.
1981 The architectures we build on and build for are determined
1982 by <prgn>make</prgn> variables using the utility
1983 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
1984 You can determine the
1985 Debian architecture and the GNU style architecture
1986 specification string for the build machine (the machine type
1987 we are building on) as well as for the host machine (the
1988 machine type we are building for). Here is a list of
1989 supported <prgn>make</prgn> variables:
1990 <list compact="compact">
1992 <tt>DEB_*_ARCH</tt> (the Debian architecture)
1995 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
1998 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2001 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2002 specification string)
2005 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2006 <tt>DEB_*_GNU_TYPE</tt>)
2009 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2010 <tt>DEB_*_GNU_TYPE</tt>)
2012 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2013 the build machine or <tt>HOST</tt> for specification of the
2018 Backward compatibility can be provided in the rules file
2019 by setting the needed variables to suitable default
2020 values; please refer to the documentation of
2021 <prgn>dpkg-architecture</prgn> for details.
2025 It is important to understand that the <tt>DEB_*_ARCH</tt>
2026 string only determines which Debian architecture we are
2027 building on or for. It should not be used to get the CPU
2028 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2029 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2030 GNU style variables should generally only be used with upstream
2034 <sect1 id="debianrules-options">
2035 <heading><file>debian/rules</file> and
2036 <tt>DEB_BUILD_OPTIONS</tt></heading>
2039 Supporting the standardized environment variable
2040 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2041 contain several flags to change how a package is compiled and
2042 built. Each flag must be in the form <var>flag</var> or
2043 <var>flag</var>=<var>options</var>. If multiple flags are
2044 given, they must be separated by whitespace.<footnote>
2045 Some packages support any delimiter, but whitespace is the
2046 easiest to parse inside a makefile and avoids ambiguity with
2047 flag values that contain commas.
2049 <var>flag</var> must start with a lowercase letter
2050 (<tt>a-z</tt>) and consist only of lowercase letters,
2051 numbers (<tt>0-9</tt>), and the characters
2052 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2053 <var>options</var> must not contain whitespace. The same
2054 tag should not be given multiple times with conflicting
2055 values. Package maintainers may assume that
2056 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2060 The meaning of the following tags has been standardized:
2064 This tag says to not run any build-time test suite
2065 provided by the package.
2069 The presence of this tag means that the package should
2070 be compiled with a minimum of optimization. For C
2071 programs, it is best to add <tt>-O0</tt> to
2072 <tt>CFLAGS</tt> (although this is usually the default).
2073 Some programs might fail to build or run at this level
2074 of optimization; it may be necessary to use
2075 <tt>-O1</tt>, for example.
2079 This tag means that the debugging symbols should not be
2080 stripped from the binary during installation, so that
2081 debugging information may be included in the package.
2083 <tag>parallel=n</tag>
2085 This tag means that the package should be built using up
2086 to <tt>n</tt> parallel processes if the package build
2087 system supports this.<footnote>
2088 Packages built with <tt>make</tt> can often implement
2089 this by passing the <tt>-j</tt><var>n</var> option to
2092 If the package build system does not support parallel
2093 builds, this string must be ignored. If the package
2094 build system only supports a lower level of concurrency
2095 than <var>n</var>, the package should be built using as
2096 many parallel processes as the package build system
2097 supports. It is up to the package maintainer to decide
2098 whether the package build times are long enough and the
2099 package build system is robust enough to make supporting
2100 parallel builds worthwhile.
2106 Unknown flags must be ignored by <file>debian/rules</file>.
2110 The following makefile snippet is an example of how one may
2111 implement the build options; you will probably have to
2112 massage this example in order to make it work for your
2114 <example compact="compact">
2117 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2118 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2119 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2120 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2122 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2127 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2128 INSTALL_PROGRAM += -s
2130 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2131 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2132 MAKEFLAGS += -j$(NUMJOBS)
2137 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2138 # Code to run the package test suite.
2145 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2146 <sect id="substvars">
2147 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2150 When <prgn>dpkg-gencontrol</prgn>,
2151 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2152 generate control files they perform variable substitutions
2153 on their output just before writing it. Variable
2154 substitutions have the form <tt>${<var>variable</var>}</tt>.
2155 The optional file <file>debian/substvars</file> contains
2156 variable substitutions to be used; variables can also be set
2157 directly from <file>debian/rules</file> using the <tt>-V</tt>
2158 option to the source packaging commands, and certain
2159 predefined variables are also available.
2163 The <file>debian/substvars</file> file is usually generated and
2164 modified dynamically by <file>debian/rules</file> targets, in
2165 which case it must be removed by the <tt>clean</tt> target.
2169 See <manref name="deb-substvars" section="5"> for full
2170 details about source variable substitutions, including the
2171 format of <file>debian/substvars</file>.</p>
2174 <sect id="debianwatch">
2175 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2178 This is an optional, recommended control file for the
2179 <tt>uscan</tt> utility which defines how to automatically
2180 scan ftp or http sites for newly available updates of the
2181 package. This is used by <url id="
2182 http://dehs.alioth.debian.org/"> and other Debian QA tools
2183 to help with quality control and maintenance of the
2184 distribution as a whole.
2189 <sect id="debianfiles">
2190 <heading>Generated files list: <file>debian/files</file></heading>
2193 This file is not a permanent part of the source tree; it
2194 is used while building packages to record which files are
2195 being generated. <prgn>dpkg-genchanges</prgn> uses it
2196 when it generates a <file>.changes</file> file.
2200 It should not exist in a shipped source package, and so it
2201 (and any backup files or temporary files such as
2202 <file>files.new</file><footnote>
2203 <file>files.new</file> is used as a temporary file by
2204 <prgn>dpkg-gencontrol</prgn> and
2205 <prgn>dpkg-distaddfile</prgn> - they write a new
2206 version of <tt>files</tt> here before renaming it,
2207 to avoid leaving a corrupted copy if an error
2209 </footnote>) should be removed by the
2210 <tt>clean</tt> target. It may also be wise to
2211 ensure a fresh start by emptying or removing it at the
2212 start of the <tt>binary</tt> target.
2216 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2217 package, it adds an entry to <file>debian/files</file> for the
2218 <file>.deb</file> file that will be created when <tt>dpkg-deb
2219 --build</tt> is run for that binary package. So for most
2220 packages all that needs to be done with this file is to
2221 delete it in the <tt>clean</tt> target.
2225 If a package upload includes files besides the source
2226 package and any binary packages whose control files were
2227 made with <prgn>dpkg-gencontrol</prgn> then they should be
2228 placed in the parent of the package's top-level directory
2229 and <prgn>dpkg-distaddfile</prgn> should be called to add
2230 the file to the list in <file>debian/files</file>.</p>
2233 <sect id="embeddedfiles">
2234 <heading>Convenience copies of code</heading>
2237 Some software packages include in their distribution convenience
2238 copies of code from other software packages, generally so that
2239 users compiling from source don't have to download multiple
2240 packages. Debian packages should not make use of these
2241 convenience copies unless the included package is explicitly
2242 intended to be used in this way.<footnote>
2243 For example, parts of the GNU build system work like this.
2245 If the included code is already in the Debian archive in the
2246 form of a library, the Debian packaging should ensure that
2247 binary packages reference the libraries already in Debian and
2248 the convenience copy is not used. If the included code is not
2249 already in Debian, it should be packaged separately as a
2250 prerequisite if possible.
2252 Having multiple copies of the same code in Debian is
2253 inefficient, often creates either static linking or shared
2254 library conflicts, and, most importantly, increases the
2255 difficulty of handling security vulnerabilities in the
2261 <sect id="readmesource">
2262 <heading>Source package handling:
2263 <file>debian/README.source</file></heading>
2266 If running <prgn>dpkg-source -x</prgn> on a source package
2267 doesn't produce the source of the package, ready for editing,
2268 and allow one to make changes and run
2269 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2270 without taking any additional steps, creating a
2271 <file>debian/README.source</file> documentation file is
2272 recommended. This file should explain how to do all of the
2275 <item>Generate the fully patched source, in a form ready for
2276 editing, that would be built to create Debian
2277 packages. Doing this with a <tt>patch</tt> target in
2278 <file>debian/rules</file> is recommended; see
2279 <ref id="debianrules">.</item>
2280 <item>Modify the source and save those modifications so that
2281 they will be applied when building the package.</item>
2282 <item>Remove source modifications that are currently being
2283 applied when building the package.</item>
2284 <item>Optionally, document what steps are necessary to
2285 upgrade the Debian source package to a new upstream version,
2286 if applicable.</item>
2288 This explanation should include specific commands and mention
2289 any additional required Debian packages. It should not assume
2290 familiarity with any specific Debian packaging system or patch
2295 This explanation may refer to a documentation file installed by
2296 one of the package's build dependencies provided that the
2297 referenced documentation clearly explains these tasks and is not
2298 a general reference manual.
2302 <file>debian/README.source</file> may also include any other
2303 information that would be helpful to someone modifying the
2304 source package. Even if the package doesn't fit the above
2305 description, maintainers are encouraged to document in a
2306 <file>debian/README.source</file> file any source package with a
2307 particularly complex or unintuitive source layout or build
2308 system (for example, a package that builds the same source
2309 multiple times to generate different binary packages).
2315 <chapt id="controlfields">
2316 <heading>Control files and their fields</heading>
2319 The package management system manipulates data represented in
2320 a common format, known as <em>control data</em>, stored in
2321 <em>control files</em>.
2322 Control files are used for source packages, binary packages and
2323 the <file>.changes</file> files which control the installation
2324 of uploaded files<footnote>
2325 <prgn>dpkg</prgn>'s internal databases are in a similar
2330 <sect id="controlsyntax">
2331 <heading>Syntax of control files</heading>
2334 A control file consists of one or more paragraphs of
2336 The paragraphs are also sometimes referred to as stanzas.
2338 The paragraphs are separated by blank lines. Some control
2339 files allow only one paragraph; others allow several, in
2340 which case each paragraph usually refers to a different
2341 package. (For example, in source packages, the first
2342 paragraph refers to the source package, and later paragraphs
2343 refer to binary packages generated from the source.)
2347 Each paragraph consists of a series of data fields; each
2348 field consists of the field name, followed by a colon and
2349 then the data/value associated with that field. It ends at
2350 the end of the (logical) line. Horizontal whitespace
2351 (spaces and tabs) may occur immediately before or after the
2352 value and is ignored there; it is conventional to put a
2353 single space after the colon. For example, a field might
2355 <example compact="compact">
2358 the field name is <tt>Package</tt> and the field value
2363 Many fields' values may span several lines; in this case
2364 each continuation line must start with a space or a tab.
2365 Any trailing spaces or tabs at the end of individual
2366 lines of a field value are ignored.
2370 In fields where it is specified that lines may not wrap,
2371 only a single line of data is allowed and whitespace is not
2372 significant in a field body. Whitespace must not appear
2373 inside names (of packages, architectures, files or anything
2374 else) or version numbers, or between the characters of
2375 multi-character version relationships.
2379 Field names are not case-sensitive, but it is usual to
2380 capitalize the field names using mixed case as shown below.
2381 Field values are case-sensitive unless the description of the
2382 field says otherwise.
2386 Blank lines, or lines consisting only of spaces and tabs,
2387 are not allowed within field values or between fields - that
2388 would mean a new paragraph.
2392 All control files must be encoded in UTF-8.
2396 <sect id="sourcecontrolfiles">
2397 <heading>Source package control files -- <file>debian/control</file></heading>
2400 The <file>debian/control</file> file contains the most vital
2401 (and version-independent) information about the source package
2402 and about the binary packages it creates.
2406 The first paragraph of the control file contains information about
2407 the source package in general. The subsequent sets each describe a
2408 binary package that the source tree builds.
2412 The fields in the general paragraph (the first one, for the source
2415 <list compact="compact">
2416 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2417 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2418 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2419 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2420 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2421 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2422 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2423 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2428 The fields in the binary package paragraphs are:
2430 <list compact="compact">
2431 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2432 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2433 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2434 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2435 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2436 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2437 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2438 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2443 The syntax and semantics of the fields are described below.
2449 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2450 generate control files for binary packages (see below), by
2451 <prgn>dpkg-genchanges</prgn> to generate the
2452 <tt>.changes</tt> file to accompany the upload, and by
2453 <prgn>dpkg-source</prgn> when it creates the
2454 <file>.dsc</file> source control file as part of a source
2455 archive. Many fields are permitted to span multiple lines in
2456 <file>debian/control</file> but not in any other control
2457 file. These tools are responsible for removing the line
2458 breaks from such fields when using fields from
2459 <file>debian/control</file> to generate other control files.
2463 The fields here may contain variable references - their
2464 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2465 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2466 when they generate output control files.
2467 See <ref id="substvars"> for details.
2471 In addition to the control file syntax described <qref
2472 id="controlsyntax">above</qref>, this file may also contain
2473 comment lines starting with <tt>#</tt> without any preceding
2474 whitespace. All such lines are ignored, even in the middle of
2475 continuation lines for a multiline field, and do not end a
2481 <sect id="binarycontrolfiles">
2482 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2485 The <file>DEBIAN/control</file> file contains the most vital
2486 (and version-dependent) information about a binary package.
2490 The fields in this file are:
2492 <list compact="compact">
2493 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2494 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2495 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2496 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2497 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2498 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2499 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2500 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2501 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2502 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2503 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2504 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2509 <sect id="debiansourcecontrolfiles">
2510 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2513 This file contains a series of fields, identified and
2514 separated just like the fields in the control file of
2515 a binary package. The fields are listed below; their
2516 syntax is described above, in <ref id="pkg-controlfields">.
2518 <list compact="compact">
2519 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2520 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2521 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2522 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2523 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2524 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2525 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2526 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2527 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2528 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2529 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2534 The source package control file is generated by
2535 <prgn>dpkg-source</prgn> when it builds the source
2536 archive, from other files in the source package,
2537 described above. When unpacking, it is checked against
2538 the files and directories in the other parts of the
2544 <sect id="debianchangesfiles">
2545 <heading>Debian changes files -- <file>.changes</file></heading>
2548 The .changes files are used by the Debian archive maintenance
2549 software to process updates to packages. They contain one
2550 paragraph which contains information from the
2551 <tt>debian/control</tt> file and other data about the
2552 source package gathered via <tt>debian/changelog</tt>
2553 and <tt>debian/rules</tt>.
2557 The fields in this file are:
2559 <list compact="compact">
2560 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2561 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2562 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2563 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2564 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2568 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2569 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2570 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2571 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2572 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2573 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2578 <sect id="controlfieldslist">
2579 <heading>List of fields</heading>
2581 <sect1 id="f-Source">
2582 <heading><tt>Source</tt></heading>
2585 This field identifies the source package name.
2589 In <file>debian/control</file> or a <file>.dsc</file> file,
2590 this field must contain only the name of the source package.
2594 In a binary package control file or a <file>.changes</file>
2595 file, the source package name may be followed by a version
2596 number in parentheses<footnote>
2597 It is customary to leave a space after the package name
2598 if a version number is specified.
2600 This version number may be omitted (and is, by
2601 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2602 the <tt>Version</tt> field of the binary package in
2603 question. The field itself may be omitted from a binary
2604 package control file when the source package has the same
2605 name and version as the binary package.
2609 Package names (both source and binary,
2610 see <ref id="f-Package">) must consist only of lower case
2611 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2612 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2613 (<tt>.</tt>). They must be at least two characters long and
2614 must start with an alphanumeric character.
2618 <sect1 id="f-Maintainer">
2619 <heading><tt>Maintainer</tt></heading>
2622 The package maintainer's name and email address. The name
2623 should come first, then the email address inside angle
2624 brackets <tt><></tt> (in RFC822 format).
2628 If the maintainer's name contains a full stop then the
2629 whole field will not work directly as an email address due
2630 to a misfeature in the syntax specified in RFC822; a
2631 program using this field as an address must check for this
2632 and correct the problem if necessary (for example by
2633 putting the name in round brackets and moving it to the
2634 end, and bringing the email address forward).
2638 <sect1 id="f-Uploaders">
2639 <heading><tt>Uploaders</tt></heading>
2642 List of the names and email addresses of co-maintainers of
2643 the package, if any. If the package has other maintainers
2644 beside the one named in the
2645 <qref id="f-Maintainer">Maintainer field</qref>, their
2646 names and email addresses should be listed here. The
2647 format is the same as that of the Maintainer tag, and
2648 multiple entries should be comma separated. Currently,
2649 this field is restricted to a single line of data. This
2650 is an optional field.
2653 Any parser that interprets the Uploaders field in
2654 <file>debian/control</file> must permit it to span multiple
2655 lines. Line breaks in an Uploaders field that spans multiple
2656 lines are not significant and the semantics of the field are
2657 the same as if the line breaks had not been present.
2661 <sect1 id="f-Changed-By">
2662 <heading><tt>Changed-By</tt></heading>
2665 The name and email address of the person who changed the
2666 said package. Usually the name of the maintainer.
2667 All the rules for the Maintainer field apply here, too.
2671 <sect1 id="f-Section">
2672 <heading><tt>Section</tt></heading>
2675 This field specifies an application area into which the package
2676 has been classified. See <ref id="subsections">.
2680 When it appears in the <file>debian/control</file> file,
2681 it gives the value for the subfield of the same name in
2682 the <tt>Files</tt> field of the <file>.changes</file> file.
2683 It also gives the default for the same field in the binary
2688 <sect1 id="f-Priority">
2689 <heading><tt>Priority</tt></heading>
2692 This field represents how important it is that the user
2693 have the package installed. See <ref id="priorities">.
2697 When it appears in the <file>debian/control</file> file,
2698 it gives the value for the subfield of the same name in
2699 the <tt>Files</tt> field of the <file>.changes</file> file.
2700 It also gives the default for the same field in the binary
2705 <sect1 id="f-Package">
2706 <heading><tt>Package</tt></heading>
2709 The name of the binary package.
2713 Binary package names must follow the same syntax and
2714 restrictions as source package names. See <ref id="f-Source">
2719 <sect1 id="f-Architecture">
2720 <heading><tt>Architecture</tt></heading>
2723 Depending on context and the control file used, the
2724 <tt>Architecture</tt> field can include the following sets of
2727 <item>A unique single word identifying a Debian machine
2728 architecture as described in <ref id="arch-spec">.
2729 <item><tt>all</tt>, which indicates an
2730 architecture-independent package.
2731 <item><tt>any</tt>, which indicates a package available
2732 for building on any architecture.
2733 <item><tt>source</tt>, which indicates a source package.
2738 In the main <file>debian/control</file> file in the source
2739 package, this field may contain the special value
2740 <tt>any</tt>, the special value <tt>all</tt>, or a list of
2741 architectures separated by spaces. If <tt>any</tt> or
2742 <tt>all</tt> appear, they must be the entire contents of the
2743 field. Most packages will use either <tt>any</tt> or
2744 <tt>all</tt>. Specifying a specific list of architectures is
2745 for the minority of cases where a program is not portable or
2746 is not useful on some architectures, and where possible the
2747 program should be made portable instead.
2751 In the source package control file <file>.dsc</file>, this
2752 field may contain either the special value <tt>any</tt> or a
2753 list of architectures separated by spaces. If a list is given,
2754 it may include (or consist solely of) the special value
2755 <tt>all</tt>. In other words, in <file>.dsc</file> files
2756 unlike the <file>debian/control</file>, <tt>all</tt> may occur
2757 in combination with specific architectures. The
2758 <tt>Architecture</tt> field in the source package control file
2759 <file>.dsc</file> is generally constructed from the
2760 <tt>Architecture</tt> fields in the
2761 <file>debian/control</file> in the source package.
2765 Specifying <tt>any</tt> indicates that the source package
2766 isn't dependent on any particular architecture and should
2767 compile fine on any one. The produced binary package(s)
2768 will either be specific to whatever the current build
2769 architecture is or will be architecture-independent.
2773 Specifying only <tt>all</tt> indicates that the source package
2774 will only build architecture-independent packages. If this is
2775 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2776 <tt>any</tt> implies that the source package will build at
2777 least one architecture-dependent package.
2781 Specifying a list of architectures indicates that the source
2782 will build an architecture-dependent package, and will only
2783 work correctly on the listed architectures. If the source
2784 package also builds at least one architecture-independent
2785 package, <tt>all</tt> will also be included in the list.
2789 In a <file>.changes</file> file, the <tt>Architecture</tt>
2790 field lists the architecture(s) of the package(s)
2791 currently being uploaded. This will be a list; if the
2792 source for the package is also being uploaded, the special
2793 entry <tt>source</tt> is also present. <tt>all</tt> will be
2794 present if any architecture-independent packages are being
2795 uploaded. <tt>any</tt> may never occur in the
2796 <tt>Architecture</tt> field in the <file>.changes</file>
2801 See <ref id="debianrules"> for information on how to get
2802 the architecture for the build process.
2806 <sect1 id="f-Essential">
2807 <heading><tt>Essential</tt></heading>
2810 This is a boolean field which may occur only in the
2811 control file of a binary package or in a per-package fields
2812 paragraph of a main source control data file.
2816 If set to <tt>yes</tt> then the package management system
2817 will refuse to remove the package (upgrading and replacing
2818 it is still possible). The other possible value is <tt>no</tt>,
2819 which is the same as not having the field at all.
2824 <heading>Package interrelationship fields:
2825 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2826 <tt>Recommends</tt>, <tt>Suggests</tt>,
2827 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2828 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2832 These fields describe the package's relationships with
2833 other packages. Their syntax and semantics are described
2834 in <ref id="relationships">.</p>
2837 <sect1 id="f-Standards-Version">
2838 <heading><tt>Standards-Version</tt></heading>
2841 The most recent version of the standards (the policy
2842 manual and associated texts) with which the package
2847 The version number has four components: major and minor
2848 version number and major and minor patch level. When the
2849 standards change in a way that requires every package to
2850 change the major number will be changed. Significant
2851 changes that will require work in many packages will be
2852 signaled by a change to the minor number. The major patch
2853 level will be changed for any change to the meaning of the
2854 standards, however small; the minor patch level will be
2855 changed when only cosmetic, typographical or other edits
2856 are made which neither change the meaning of the document
2857 nor affect the contents of packages.
2861 Thus only the first three components of the policy version
2862 are significant in the <em>Standards-Version</em> control
2863 field, and so either these three components or all four
2864 components may be specified.<footnote>
2865 In the past, people specified the full version number
2866 in the Standards-Version field, for example "2.3.0.0".
2867 Since minor patch-level changes don't introduce new
2868 policy, it was thought it would be better to relax
2869 policy and only require the first 3 components to be
2870 specified, in this example "2.3.0". All four
2871 components may still be used if someone wishes to do so.
2877 <sect1 id="f-Version">
2878 <heading><tt>Version</tt></heading>
2881 The version number of a package. The format is:
2882 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2886 The three components here are:
2888 <tag><var>epoch</var></tag>
2891 This is a single (generally small) unsigned integer. It
2892 may be omitted, in which case zero is assumed. If it is
2893 omitted then the <var>upstream_version</var> may not
2898 It is provided to allow mistakes in the version numbers
2899 of older versions of a package, and also a package's
2900 previous version numbering schemes, to be left behind.
2904 <tag><var>upstream_version</var></tag>
2907 This is the main part of the version number. It is
2908 usually the version number of the original ("upstream")
2909 package from which the <file>.deb</file> file has been made,
2910 if this is applicable. Usually this will be in the same
2911 format as that specified by the upstream author(s);
2912 however, it may need to be reformatted to fit into the
2913 package management system's format and comparison
2918 The comparison behavior of the package management system
2919 with respect to the <var>upstream_version</var> is
2920 described below. The <var>upstream_version</var>
2921 portion of the version number is mandatory.
2925 The <var>upstream_version</var> may contain only
2926 alphanumerics<footnote>
2927 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2929 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2930 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2931 tilde) and should start with a digit. If there is no
2932 <var>debian_revision</var> then hyphens are not allowed;
2933 if there is no <var>epoch</var> then colons are not
2938 <tag><var>debian_revision</var></tag>
2941 This part of the version number specifies the version of
2942 the Debian package based on the upstream version. It
2943 may contain only alphanumerics and the characters
2944 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2945 tilde) and is compared in the same way as the
2946 <var>upstream_version</var> is.
2950 It is optional; if it isn't present then the
2951 <var>upstream_version</var> may not contain a hyphen.
2952 This format represents the case where a piece of
2953 software was written specifically to be turned into a
2954 Debian package, and so there is only one "debianisation"
2955 of it and therefore no revision indication is required.
2959 It is conventional to restart the
2960 <var>debian_revision</var> at <tt>1</tt> each time the
2961 <var>upstream_version</var> is increased.
2965 The package management system will break the version
2966 number apart at the last hyphen in the string (if there
2967 is one) to determine the <var>upstream_version</var> and
2968 <var>debian_revision</var>. The absence of a
2969 <var>debian_revision</var> is equivalent to a
2970 <var>debian_revision</var> of <tt>0</tt>.
2977 When comparing two version numbers, first the <var>epoch</var>
2978 of each are compared, then the <var>upstream_version</var> if
2979 <var>epoch</var> is equal, and then <var>debian_revision</var>
2980 if <var>upstream_version</var> is also equal.
2981 <var>epoch</var> is compared numerically. The
2982 <var>upstream_version</var> and <var>debian_revision</var>
2983 parts are compared by the package management system using the
2984 following algorithm:
2988 The strings are compared from left to right.
2992 First the initial part of each string consisting entirely of
2993 non-digit characters is determined. These two parts (one of
2994 which may be empty) are compared lexically. If a difference
2995 is found it is returned. The lexical comparison is a
2996 comparison of ASCII values modified so that all the letters
2997 sort earlier than all the non-letters and so that a tilde
2998 sorts before anything, even the end of a part. For example,
2999 the following parts are in sorted order from earliest to
3000 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3001 <tt>a</tt>.<footnote>
3002 One common use of <tt>~</tt> is for upstream pre-releases.
3003 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3004 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3009 Then the initial part of the remainder of each string which
3010 consists entirely of digit characters is determined. The
3011 numerical values of these two parts are compared, and any
3012 difference found is returned as the result of the comparison.
3013 For these purposes an empty string (which can only occur at
3014 the end of one or both version strings being compared) counts
3019 These two steps (comparing and removing initial non-digit
3020 strings and initial digit strings) are repeated until a
3021 difference is found or both strings are exhausted.
3025 Note that the purpose of epochs is to allow us to leave behind
3026 mistakes in version numbering, and to cope with situations
3027 where the version numbering scheme changes. It is
3028 <em>not</em> intended to cope with version numbers containing
3029 strings of letters which the package management system cannot
3030 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3031 silly orderings (the author of this manual has heard of a
3032 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
3033 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
3034 <tt>2</tt> and so forth).
3038 <sect1 id="f-Description">
3039 <heading><tt>Description</tt></heading>
3042 In a source or binary control file, the <tt>Description</tt>
3043 field contains a description of the binary package, consisting
3044 of two parts, the synopsis or the short description, and the
3045 long description. The field's format is as follows:
3050 Description: <single line synopsis>
3051 <extended description over several lines>
3056 The lines in the extended description can have these formats:
3062 Those starting with a single space are part of a paragraph.
3063 Successive lines of this form will be word-wrapped when
3064 displayed. The leading space will usually be stripped off.
3068 Those starting with two or more spaces. These will be
3069 displayed verbatim. If the display cannot be panned
3070 horizontally, the displaying program will line wrap them "hard"
3071 (i.e., without taking account of word breaks). If it can they
3072 will be allowed to trail off to the right. None, one or two
3073 initial spaces may be deleted, but the number of spaces
3074 deleted from each line will be the same (so that you can have
3075 indenting work correctly, for example).
3079 Those containing a single space followed by a single full stop
3080 character. These are rendered as blank lines. This is the
3081 <em>only</em> way to get a blank line<footnote>
3082 Completely empty lines will not be rendered as blank lines.
3083 Instead, they will cause the parser to think you're starting
3084 a whole new record in the control file, and will therefore
3085 likely abort with an error.
3090 Those containing a space, a full stop and some more characters.
3091 These are for future expansion. Do not use them.
3097 Do not use tab characters. Their effect is not predictable.
3101 See <ref id="descriptions"> for further information on this.
3105 In a <file>.changes</file> file, the <tt>Description</tt>
3106 field contains a summary of the descriptions for the packages
3107 being uploaded. For this case, the first line of the field
3108 value (the part on the same line as <tt>Description:</tt>) is
3109 always empty. The content of the field is expressed as
3110 continuation lines, one line per package. Each line is
3111 indented by one space and contains the name of a binary
3112 package, a space, a hyphen (<tt>-</tt>), a space, and the
3113 short description line from that package.
3117 <sect1 id="f-Distribution">
3118 <heading><tt>Distribution</tt></heading>
3121 In a <file>.changes</file> file or parsed changelog output
3122 this contains the (space-separated) name(s) of the
3123 distribution(s) where this version of the package should
3124 be installed. Valid distributions are determined by the
3125 archive maintainers.<footnote>
3126 Example distribution names in the Debian archive used in
3127 <file>.changes</file> files are:
3128 <taglist compact="compact">
3129 <tag><em>unstable</em></tag>
3131 This distribution value refers to the
3132 <em>developmental</em> part of the Debian distribution
3133 tree. Most new packages, new upstream versions of
3134 packages and bug fixes go into the <em>unstable</em>
3138 <tag><em>experimental</em></tag>
3140 The packages with this distribution value are deemed
3141 by their maintainers to be high risk. Oftentimes they
3142 represent early beta or developmental packages from
3143 various sources that the maintainers want people to
3144 try, but are not ready to be a part of the other parts
3145 of the Debian distribution tree.
3150 Others are used for updating stable releases or for
3151 security uploads. More information is available in the
3152 Debian Developer's Reference, section "The Debian
3156 The Debian archive software only supports listing a single
3157 distribution. Migration of packages to other distributions is
3158 handled outside of the upload process.
3163 <heading><tt>Date</tt></heading>
3166 This field includes the date the package was built or last edited.
3170 The value of this field is usually extracted from the
3171 <file>debian/changelog</file> file - see
3172 <ref id="dpkgchangelog">).
3176 <sect1 id="f-Format">
3177 <heading><tt>Format</tt></heading>
3180 This field specifies a format revision for the file.
3181 The most current format described in the Policy Manual
3182 is version <strong>1.5</strong>. The syntax of the
3183 format value is the same as that of a package version
3184 number except that no epoch or Debian revision is allowed
3185 - see <ref id="f-Version">.
3189 <sect1 id="f-Urgency">
3190 <heading><tt>Urgency</tt></heading>
3193 This is a description of how important it is to upgrade to
3194 this version from previous ones. It consists of a single
3195 keyword taking one of the values <tt>low</tt>,
3196 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3197 <tt>critical</tt><footnote>
3198 Other urgency values are supported with configuration
3199 changes in the archive software but are not used in Debian.
3200 The urgency affects how quickly a package will be considered
3201 for inclusion into the <tt>testing</tt> distribution and
3202 gives an indication of the importance of any fixes included
3203 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3204 treated as synonymous.
3205 </footnote> (not case-sensitive) followed by an optional
3206 commentary (separated by a space) which is usually in
3207 parentheses. For example:
3210 Urgency: low (HIGH for users of diversions)
3216 The value of this field is usually extracted from the
3217 <file>debian/changelog</file> file - see
3218 <ref id="dpkgchangelog">.
3222 <sect1 id="f-Changes">
3223 <heading><tt>Changes</tt></heading>
3226 This field contains the human-readable changes data, describing
3227 the differences between the last version and the current one.
3231 The first line of the field value (the part on the same line
3232 as <tt>Changes:</tt>) is always empty. The content of the
3233 field is expressed as continuation lines, with each line
3234 indented by at least one space. Blank lines must be
3235 represented by a line consisting only of a space and a full
3240 The value of this field is usually extracted from the
3241 <file>debian/changelog</file> file - see
3242 <ref id="dpkgchangelog">).
3246 Each version's change information should be preceded by a
3247 "title" line giving at least the version, distribution(s)
3248 and urgency, in a human-readable way.
3252 If data from several versions is being returned the entry
3253 for the most recent version should be returned first, and
3254 entries should be separated by the representation of a
3255 blank line (the "title" line may also be followed by the
3256 representation of a blank line).
3260 <sect1 id="f-Binary">
3261 <heading><tt>Binary</tt></heading>
3264 This field is a list of binary packages. Its syntax and
3265 meaning varies depending on the control file in which it
3270 When it appears in the <file>.dsc</file> file, it lists binary
3271 packages which a source package can produce, separated by
3273 A space after each comma is conventional.
3274 </footnote>. It may span multiple lines. The source package
3275 does not necessarily produce all of these binary packages for
3276 every architecture. The source control file doesn't contain
3277 details of which architectures are appropriate for which of
3278 the binary packages.
3282 When it appears in a <file>.changes</file> file, it lists the
3283 names of the binary packages being uploaded, separated by
3284 whitespace (not commas). It may span multiple lines.
3288 <sect1 id="f-Installed-Size">
3289 <heading><tt>Installed-Size</tt></heading>
3292 This field appears in the control files of binary packages,
3293 and in the <file>Packages</file> files. It gives an estimate
3294 of the total amount of disk space required to install the
3295 named package. Actual installed size may vary based on block
3296 size, file system properties, or actions taken by package
3301 The disk space is given as the integer value of the estimated
3302 installed size in bytes, divided by 1024 and rounded up.
3306 <sect1 id="f-Files">
3307 <heading><tt>Files</tt></heading>
3310 This field contains a list of files with information about
3311 each one. The exact information and syntax varies with
3316 In all cases, Files is a multiline field. The first line of
3317 the field value (the part on the same line as <tt>Files:</tt>)
3318 is always empty. The content of the field is expressed as
3319 continuation lines, one line per file. Each line must be
3320 indented by one space and contain a number of sub-fields,
3321 separated by spaces, as described below.
3325 In the <file>.dsc</file> file, each line contains the MD5
3326 checksum, size and filename of the tar file and (if
3327 applicable) diff file which make up the remainder of the
3328 source package<footnote>
3329 That is, the parts which are not the <tt>.dsc</tt>.
3330 </footnote>. For example:
3333 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3334 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3336 The exact forms of the filenames are described
3337 in <ref id="pkg-sourcearchives">.
3341 In the <file>.changes</file> file this contains one line per
3342 file being uploaded. Each line contains the MD5 checksum,
3343 size, section and priority and the filename. For example:
3346 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3347 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3348 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3349 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3351 The <qref id="f-Section">section</qref>
3352 and <qref id="f-Priority">priority</qref> are the values of
3353 the corresponding fields in the main source control file. If
3354 no section or priority is specified then <tt>-</tt> should be
3355 used, though section and priority values must be specified for
3356 new packages to be installed properly.
3360 The special value <tt>byhand</tt> for the section in a
3361 <tt>.changes</tt> file indicates that the file in question
3362 is not an ordinary package file and must by installed by
3363 hand by the distribution maintainers. If the section is
3364 <tt>byhand</tt> the priority should be <tt>-</tt>.
3368 If a new Debian revision of a package is being shipped and
3369 no new original source archive is being distributed the
3370 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3371 entry for the original source archive
3372 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
3373 but the <file>.changes</file> file should leave it out. In
3374 this case the original source archive on the distribution
3375 site must match exactly, byte-for-byte, the original
3376 source archive which was used to generate the
3377 <file>.dsc</file> file and diff which are being uploaded.</p>
3380 <sect1 id="f-Closes">
3381 <heading><tt>Closes</tt></heading>
3384 A space-separated list of bug report numbers that the upload
3385 governed by the .changes file closes.
3389 <sect1 id="f-Homepage">
3390 <heading><tt>Homepage</tt></heading>
3393 The URL of the web site for this package, preferably (when
3394 applicable) the site from which the original source can be
3395 obtained and any additional upstream documentation or
3396 information may be found. The content of this field is a
3397 simple URL without any surrounding characters such as
3405 <heading>User-defined fields</heading>
3408 Additional user-defined fields may be added to the
3409 source package control file. Such fields will be
3410 ignored, and not copied to (for example) binary or
3411 source package control files or upload control files.
3415 If you wish to add additional unsupported fields to
3416 these output files you should use the mechanism
3421 Fields in the main source control information file with
3422 names starting <tt>X</tt>, followed by one or more of
3423 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3424 be copied to the output files. Only the part of the
3425 field name after the hyphen will be used in the output
3426 file. Where the letter <tt>B</tt> is used the field
3427 will appear in binary package control files, where the
3428 letter <tt>S</tt> is used in source package control
3429 files and where <tt>C</tt> is used in upload control
3430 (<tt>.changes</tt>) files.
3434 For example, if the main source information control file
3437 XBS-Comment: I stand between the candle and the star.
3439 then the binary and source package control files will contain the
3442 Comment: I stand between the candle and the star.
3451 <chapt id="maintainerscripts">
3452 <heading>Package maintainer scripts and installation procedure</heading>
3455 <heading>Introduction to package maintainer scripts</heading>
3458 It is possible to supply scripts as part of a package which
3459 the package management system will run for you when your
3460 package is installed, upgraded or removed.
3464 These scripts are the files <prgn>preinst</prgn>,
3465 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3466 <prgn>postrm</prgn> in the control area of the package.
3467 They must be proper executable files; if they are scripts
3468 (which is recommended), they must start with the usual
3469 <tt>#!</tt> convention. They should be readable and
3470 executable by anyone, and must not be world-writable.
3474 The package management system looks at the exit status from
3475 these scripts. It is important that they exit with a
3476 non-zero status if there is an error, so that the package
3477 management system can stop its processing. For shell
3478 scripts this means that you <em>almost always</em> need to
3479 use <tt>set -e</tt> (this is usually true when writing shell
3480 scripts, in fact). It is also important, of course, that
3481 they exit with a zero status if everything went well.
3485 Additionally, packages interacting with users using
3486 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3487 install a <prgn>config</prgn> script in the control area,
3488 see <ref id="maintscriptprompt"> for details.
3492 When a package is upgraded a combination of the scripts from
3493 the old and new packages is called during the upgrade
3494 procedure. If your scripts are going to be at all
3495 complicated you need to be aware of this, and may need to
3496 check the arguments to your scripts.
3500 Broadly speaking the <prgn>preinst</prgn> is called before
3501 (a particular version of) a package is installed, and the
3502 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3503 before (a version of) a package is removed and the
3504 <prgn>postrm</prgn> afterwards.
3508 Programs called from maintainer scripts should not normally
3509 have a path prepended to them. Before installation is
3510 started, the package management system checks to see if the
3511 programs <prgn>ldconfig</prgn>,
3512 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3513 and <prgn>update-rc.d</prgn> can be found via the
3514 <tt>PATH</tt> environment variable. Those programs, and any
3515 other program that one would expect to be in the
3516 <tt>PATH</tt>, should thus be invoked without an absolute
3517 pathname. Maintainer scripts should also not reset the
3518 <tt>PATH</tt>, though they might choose to modify it by
3519 prepending or appending package-specific directories. These
3520 considerations really apply to all shell scripts.</p>
3523 <sect id="idempotency">
3524 <heading>Maintainer scripts idempotency</heading>
3527 It is necessary for the error recovery procedures that the
3528 scripts be idempotent. This means that if it is run
3529 successfully, and then it is called again, it doesn't bomb
3530 out or cause any harm, but just ensures that everything is
3531 the way it ought to be. If the first call failed, or
3532 aborted half way through for some reason, the second call
3533 should merely do the things that were left undone the first
3534 time, if any, and exit with a success status if everything
3536 This is so that if an error occurs, the user interrupts
3537 <prgn>dpkg</prgn> or some other unforeseen circumstance
3538 happens you don't leave the user with a badly-broken
3539 package when <prgn>dpkg</prgn> attempts to repeat the
3545 <sect id="controllingterminal">
3546 <heading>Controlling terminal for maintainer scripts</heading>
3549 The maintainer scripts are guaranteed to run with a
3550 controlling terminal and can interact with the user.
3551 Because these scripts may be executed with standard output
3552 redirected into a pipe for logging purposes, Perl scripts
3553 should set unbuffered output by setting <tt>$|=1</tt> so
3554 that the output is printed immediately rather than being
3558 <sect id="exitstatus">
3559 <heading>Exit status</heading>
3562 Each script must return a zero exit status for
3563 success, or a nonzero one for failure, since the package
3564 management system looks for the exit status of these scripts
3565 and determines what action to take next based on that datum.
3569 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3574 <list compact="compact">
3576 <var>new-preinst</var> <tt>install</tt>
3579 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3582 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3585 <var>old-preinst</var> <tt>abort-upgrade</tt>
3586 <var>new-version</var>
3591 <list compact="compact">
3593 <var>postinst</var> <tt>configure</tt>
3594 <var>most-recently-configured-version</var>
3597 <var>old-postinst</var> <tt>abort-upgrade</tt>
3598 <var>new-version</var>
3601 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3602 <tt>in-favour</tt> <var>package</var>
3603 <var>new-version</var>
3606 <var>postinst</var> <tt>abort-remove</tt>
3609 <var>deconfigured's-postinst</var>
3610 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3611 <var>failed-install-package</var> <var>version</var>
3612 [<tt>removing</tt> <var>conflicting-package</var>
3618 <list compact="compact">
3620 <var>prerm</var> <tt>remove</tt>
3623 <var>old-prerm</var> <tt>upgrade</tt>
3624 <var>new-version</var>
3627 <var>new-prerm</var> <tt>failed-upgrade</tt>
3628 <var>old-version</var>
3631 <var>conflictor's-prerm</var> <tt>remove</tt>
3632 <tt>in-favour</tt> <var>package</var>
3633 <var>new-version</var>
3636 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3637 <tt>in-favour</tt> <var>package-being-installed</var>
3638 <var>version</var> [<tt>removing</tt>
3639 <var>conflicting-package</var>
3645 <list compact="compact">
3647 <var>postrm</var> <tt>remove</tt>
3650 <var>postrm</var> <tt>purge</tt>
3653 <var>old-postrm</var> <tt>upgrade</tt>
3654 <var>new-version</var>
3657 <var>new-postrm</var> <tt>failed-upgrade</tt>
3658 <var>old-version</var>
3661 <var>new-postrm</var> <tt>abort-install</tt>
3664 <var>new-postrm</var> <tt>abort-install</tt>
3665 <var>old-version</var>
3668 <var>new-postrm</var> <tt>abort-upgrade</tt>
3669 <var>old-version</var>
3672 <var>disappearer's-postrm</var> <tt>disappear</tt>
3673 <var>overwriter</var>
3674 <var>overwriter-version</var>
3680 <sect id="unpackphase">
3681 <heading>Details of unpack phase of installation or upgrade</heading>
3684 The procedure on installation/upgrade/overwrite/disappear
3685 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3686 stage of <tt>dpkg --install</tt>) is as follows. In each
3687 case, if a major error occurs (unless listed below) the
3688 actions are, in general, run backwards - this means that the
3689 maintainer scripts are run with different arguments in
3690 reverse order. These are the "error unwind" calls listed
3697 If a version of the package is already installed, call
3698 <example compact="compact">
3699 <var>old-prerm</var> upgrade <var>new-version</var>
3703 If the script runs but exits with a non-zero
3704 exit status, <prgn>dpkg</prgn> will attempt:
3705 <example compact="compact">
3706 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3708 If this works, the upgrade continues. If this
3709 does not work, the error unwind:
3710 <example compact="compact">
3711 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3713 If this works, then the old-version is
3714 "Installed", if not, the old version is in a
3715 "Failed-Config" state.
3721 If a "conflicting" package is being removed at the same time,
3722 or if any package will be broken (due to <tt>Breaks</tt>):
3725 If <tt>--auto-deconfigure</tt> is
3726 specified, call, for each package to be deconfigured
3727 due to <tt>Breaks</tt>:
3728 <example compact="compact">
3729 <var>deconfigured's-prerm</var> deconfigure \
3730 in-favour <var>package-being-installed</var> <var>version</var>
3733 <example compact="compact">
3734 <var>deconfigured's-postinst</var> abort-deconfigure \
3735 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3737 The deconfigured packages are marked as
3738 requiring configuration, so that if
3739 <tt>--install</tt> is used they will be
3740 configured again if possible.
3743 If any packages depended on a conflicting
3744 package being removed and <tt>--auto-deconfigure</tt> is
3745 specified, call, for each such package:
3746 <example compact="compact">
3747 <var>deconfigured's-prerm</var> deconfigure \
3748 in-favour <var>package-being-installed</var> <var>version</var> \
3749 removing <var>conflicting-package</var> <var>version</var>
3752 <example compact="compact">
3753 <var>deconfigured's-postinst</var> abort-deconfigure \
3754 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3755 removing <var>conflicting-package</var> <var>version</var>
3757 The deconfigured packages are marked as
3758 requiring configuration, so that if
3759 <tt>--install</tt> is used they will be
3760 configured again if possible.
3763 To prepare for removal of each conflicting package, call:
3764 <example compact="compact">
3765 <var>conflictor's-prerm</var> remove \
3766 in-favour <var>package</var> <var>new-version</var>
3769 <example compact="compact">
3770 <var>conflictor's-postinst</var> abort-remove \
3771 in-favour <var>package</var> <var>new-version</var>
3780 If the package is being upgraded, call:
3781 <example compact="compact">
3782 <var>new-preinst</var> upgrade <var>old-version</var>
3784 If this fails, we call:
3786 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3793 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3795 is called. If this works, then the old version
3796 is in an "Installed" state, or else it is left
3797 in an "Unpacked" state.
3802 If it fails, then the old version is left
3803 in an "Half-Installed" state.
3810 Otherwise, if the package had some configuration
3811 files from a previous version installed (i.e., it
3812 is in the "configuration files only" state):
3813 <example compact="compact">
3814 <var>new-preinst</var> install <var>old-version</var>
3818 <var>new-postrm</var> abort-install <var>old-version</var>
3820 If this fails, the package is left in a
3821 "Half-Installed" state, which requires a
3822 reinstall. If it works, the packages is left in
3823 a "Config Files" state.
3826 Otherwise (i.e., the package was completely purged):
3827 <example compact="compact">
3828 <var>new-preinst</var> install
3831 <example compact="compact">
3832 <var>new-postrm</var> abort-install
3834 If the error-unwind fails, the package is in a
3835 "Half Installed" phase, and requires a
3836 reinstall. If the error unwind works, the
3837 package is in a not installed state.
3844 The new package's files are unpacked, overwriting any
3845 that may be on the system already, for example any
3846 from the old version of the same package or from
3847 another package. Backups of the old files are kept
3848 temporarily, and if anything goes wrong the package
3849 management system will attempt to put them back as
3850 part of the error unwind.
3854 It is an error for a package to contain files which
3855 are on the system in another package, unless
3856 <tt>Replaces</tt> is used (see <ref id="replaces">).
3858 The following paragraph is not currently the case:
3859 Currently the <tt>- - force-overwrite</tt> flag is
3860 enabled, downgrading it to a warning, but this may not
3866 It is a more serious error for a package to contain a
3867 plain file or other kind of non-directory where another
3868 package has a directory (again, unless
3869 <tt>Replaces</tt> is used). This error can be
3870 overridden if desired using
3871 <tt>--force-overwrite-dir</tt>, but this is not
3876 Packages which overwrite each other's files produce
3877 behavior which, though deterministic, is hard for the
3878 system administrator to understand. It can easily
3879 lead to "missing" programs if, for example, a package
3880 is installed which overwrites a file from another
3881 package, and is then removed again.<footnote>
3882 Part of the problem is due to what is arguably a
3883 bug in <prgn>dpkg</prgn>.
3888 A directory will never be replaced by a symbolic link
3889 to a directory or vice versa; instead, the existing
3890 state (symlink or not) will be left alone and
3891 <prgn>dpkg</prgn> will follow the symlink if there is
3900 If the package is being upgraded, call
3901 <example compact="compact">
3902 <var>old-postrm</var> upgrade <var>new-version</var>
3906 If this fails, <prgn>dpkg</prgn> will attempt:
3907 <example compact="compact">
3908 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3910 If this works, installation continues. If not,
3912 <example compact="compact">
3913 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3915 If this fails, the old version is left in a
3916 "Half Installed" state. If it works, dpkg now
3918 <example compact="compact">
3919 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3921 If this fails, the old version is left in a
3922 "Half Installed" state. If it works, dpkg now
3924 <example compact="compact">
3925 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3927 If this fails, the old version is in an
3934 This is the point of no return - if
3935 <prgn>dpkg</prgn> gets this far, it won't back off
3936 past this point if an error occurs. This will
3937 leave the package in a fairly bad state, which
3938 will require a successful re-installation to clear
3939 up, but it's when <prgn>dpkg</prgn> starts doing
3940 things that are irreversible.
3945 Any files which were in the old version of the package
3946 but not in the new are removed.
3950 The new file list replaces the old.
3954 The new maintainer scripts replace the old.
3958 Any packages all of whose files have been overwritten
3959 during the installation, and which aren't required for
3960 dependencies, are considered to have been removed.
3961 For each such package
3964 <prgn>dpkg</prgn> calls:
3965 <example compact="compact">
3966 <var>disappearer's-postrm</var> disappear \
3967 <var>overwriter</var> <var>overwriter-version</var>
3971 The package's maintainer scripts are removed.
3974 It is noted in the status database as being in a
3975 sane state, namely not installed (any conffiles
3976 it may have are ignored, rather than being
3977 removed by <prgn>dpkg</prgn>). Note that
3978 disappearing packages do not have their prerm
3979 called, because <prgn>dpkg</prgn> doesn't know
3980 in advance that the package is going to
3987 Any files in the package we're unpacking that are also
3988 listed in the file lists of other packages are removed
3989 from those lists. (This will lobotomize the file list
3990 of the "conflicting" package if there is one.)
3994 The backup files made during installation, above, are
4000 The new package's status is now sane, and recorded as
4005 Here is another point of no return - if the
4006 conflicting package's removal fails we do not unwind
4007 the rest of the installation; the conflicting package
4008 is left in a half-removed limbo.
4013 If there was a conflicting package we go and do the
4014 removal actions (described below), starting with the
4015 removal of the conflicting package's files (any that
4016 are also in the package being installed have already
4017 been removed from the conflicting package's file list,
4018 and so do not get removed now).
4024 <sect id="configdetails"><heading>Details of configuration</heading>
4027 When we configure a package (this happens with <tt>dpkg
4028 --install</tt> and <tt>dpkg --configure</tt>), we first
4029 update any <tt>conffile</tt>s and then call:
4030 <example compact="compact">
4031 <var>postinst</var> configure <var>most-recently-configured-version</var>
4036 No attempt is made to unwind after errors during
4037 configuration. If the configuration fails, the package is in
4038 a "Failed Config" state, and an error message is generated.
4042 If there is no most recently configured version
4043 <prgn>dpkg</prgn> will pass a null argument.
4046 Historical note: Truly ancient (pre-1997) versions of
4047 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4048 (including the angle brackets) in this case. Even older
4049 ones did not pass a second argument at all, under any
4050 circumstance. Note that upgrades using such an old dpkg
4051 version are unlikely to work for other reasons, even if
4052 this old argument behavior is handled by your postinst script.
4058 <sect id="removedetails"><heading>Details of removal and/or
4059 configuration purging</heading>
4065 <example compact="compact">
4066 <var>prerm</var> remove
4070 If prerm fails during replacement due to conflict
4072 <var>conflictor's-postinst</var> abort-remove \
4073 in-favour <var>package</var> <var>new-version</var>
4077 <var>postinst</var> abort-remove
4081 If this fails, the package is in a "Failed-Config"
4082 state, or else it remains "Installed".
4086 The package's files are removed (except <tt>conffile</tt>s).
4089 <example compact="compact">
4090 <var>postrm</var> remove
4094 If it fails, there's no error unwind, and the package is in
4095 an "Half-Installed" state.
4100 All the maintainer scripts except the <prgn>postrm</prgn>
4105 If we aren't purging the package we stop here. Note
4106 that packages which have no <prgn>postrm</prgn> and no
4107 <tt>conffile</tt>s are automatically purged when
4108 removed, as there is no difference except for the
4109 <prgn>dpkg</prgn> status.
4113 The <tt>conffile</tt>s and any backup files
4114 (<tt>~</tt>-files, <tt>#*#</tt> files,
4115 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4120 <example compact="compact">
4121 <var>postrm</var> purge
4125 If this fails, the package remains in a "Config-Files"
4130 The package's file list is removed.
4139 <chapt id="relationships">
4140 <heading>Declaring relationships between packages</heading>
4142 <sect id="depsyntax">
4143 <heading>Syntax of relationship fields</heading>
4146 These fields all have a uniform syntax. They are a list of
4147 package names separated by commas.
4151 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4152 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4153 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4154 control file fields of the package, which declare
4155 dependencies on other packages, the package names listed may
4156 also include lists of alternative package names, separated
4157 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4158 if any one of the alternative packages is installed, that
4159 part of the dependency is considered to be satisfied.
4163 All of the fields except for <tt>Provides</tt> may restrict
4164 their applicability to particular versions of each named
4165 package. This is done in parentheses after each individual
4166 package name; the parentheses should contain a relation from
4167 the list below followed by a version number, in the format
4168 described in <ref id="f-Version">.
4172 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4173 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4174 strictly earlier, earlier or equal, exactly equal, later or
4175 equal and strictly later, respectively. The deprecated
4176 forms <tt><</tt> and <tt>></tt> were used to mean
4177 earlier/later or equal, rather than strictly earlier/later,
4178 so they should not appear in new packages (though
4179 <prgn>dpkg</prgn> still supports them).
4183 Whitespace may appear at any point in the version
4184 specification subject to the rules in <ref
4185 id="controlsyntax">, and must appear where it's necessary to
4186 disambiguate; it is not otherwise significant. All of the
4187 relationship fields may span multiple lines. For
4188 consistency and in case of future changes to
4189 <prgn>dpkg</prgn> it is recommended that a single space be
4190 used after a version relationship and before a version
4191 number; it is also conventional to put a single space after
4192 each comma, on either side of each vertical bar, and before
4193 each open parenthesis. When wrapping a relationship field, it
4194 is conventional to do so after a comma and before the space
4195 following that comma.
4199 For example, a list of dependencies might appear as:
4200 <example compact="compact">
4203 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4208 All fields that specify build-time relationships
4209 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4210 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4211 may be restricted to a certain set of architectures. This
4212 is indicated in brackets after each individual package name and
4213 the optional version specification. The brackets enclose a
4214 list of Debian architecture names separated by whitespace.
4215 Exclamation marks may be prepended to each of the names.
4216 (It is not permitted for some names to be prepended with
4217 exclamation marks while others aren't.) If the current Debian
4218 host architecture is not in this list and there are no
4219 exclamation marks in the list, or it is in the list with a
4220 prepended exclamation mark, the package name and the
4221 associated version specification are ignored completely for
4222 the purposes of defining the relationships.
4227 <example compact="compact">
4229 Build-Depends-Indep: texinfo
4230 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4231 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4233 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4234 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4235 <tt>gnumach-dev</tt> only on hurd-i386.
4239 If the architecture-restricted dependency is part of a set of
4240 alternatives using <tt>|</tt>, that alternative is ignored
4241 completely on architectures that do not match the restriction.
4243 <example compact="compact">
4244 Build-Depends: foo [!i386] | bar [!amd64]
4246 is equivalent to <tt>bar</tt> on the i386 architecture, to
4247 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4248 bar</tt> on all other architectures.
4252 Note that the binary package relationship fields such as
4253 <tt>Depends</tt> appear in one of the binary package
4254 sections of the control file, whereas the build-time
4255 relationships such as <tt>Build-Depends</tt> appear in the
4256 source package section of the control file (which is the
4261 <sect id="binarydeps">
4262 <heading>Binary Dependencies - <tt>Depends</tt>,
4263 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4264 <tt>Pre-Depends</tt>
4268 Packages can declare in their control file that they have
4269 certain relationships to other packages - for example, that
4270 they may not be installed at the same time as certain other
4271 packages, and/or that they depend on the presence of others.
4275 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4276 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4277 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4278 <tt>Breaks</tt> is described in <ref id="breaks">, and
4279 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4280 rest are described below.
4284 These seven fields are used to declare a dependency
4285 relationship by one package on another. Except for
4286 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4287 depending (binary) package's control file.
4288 (<tt>Enhances</tt> appears in the recommending package's
4289 control file, and <tt>Breaks</tt> appears in the version of
4290 depended-on package which causes the named package to
4295 A <tt>Depends</tt> field takes effect <em>only</em> when a
4296 package is to be configured. It does not prevent a package
4297 being on the system in an unconfigured state while its
4298 dependencies are unsatisfied, and it is possible to replace
4299 a package whose dependencies are satisfied and which is
4300 properly installed with a different version whose
4301 dependencies are not and cannot be satisfied; when this is
4302 done the depending package will be left unconfigured (since
4303 attempts to configure it will give errors) and will not
4304 function properly. If it is necessary, a
4305 <tt>Pre-Depends</tt> field can be used, which has a partial
4306 effect even when a package is being unpacked, as explained
4307 in detail below. (The other three dependency fields,
4308 <tt>Recommends</tt>, <tt>Suggests</tt> and
4309 <tt>Enhances</tt>, are only used by the various front-ends
4310 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4311 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4315 For this reason packages in an installation run are usually
4316 all unpacked first and all configured later; this gives
4317 later versions of packages with dependencies on later
4318 versions of other packages the opportunity to have their
4319 dependencies satisfied.
4323 In case of circular dependencies, since installation or
4324 removal order honoring the dependency order can't be
4325 established, dependency loops are broken at some point
4326 (based on rules below), and some packages may not be able to
4327 rely on their dependencies being present when being
4328 installed or removed, depending on which side of the break
4329 of the circular dependency loop they happen to be on. If one
4330 of the packages in the loop has no postinst script, then the
4331 cycle will be broken at that package, so as to ensure that
4332 all postinst scripts run with the dependencies properly
4333 configured if this is possible. Otherwise the breaking point
4338 The <tt>Depends</tt> field thus allows package maintainers
4339 to impose an order in which packages should be configured.
4343 The meaning of the five dependency fields is as follows:
4345 <tag><tt>Depends</tt></tag>
4348 This declares an absolute dependency. A package will
4349 not be configured unless all of the packages listed in
4350 its <tt>Depends</tt> field have been correctly
4355 The <tt>Depends</tt> field should be used if the
4356 depended-on package is required for the depending
4357 package to provide a significant amount of
4362 The <tt>Depends</tt> field should also be used if the
4363 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4364 <prgn>postrm</prgn> scripts require the package to be
4365 present in order to run. Note, however, that the
4366 <prgn>postrm</prgn> cannot rely on any non-essential
4367 packages to be present during the <tt>purge</tt>
4371 <tag><tt>Recommends</tt></tag>
4374 This declares a strong, but not absolute, dependency.
4378 The <tt>Recommends</tt> field should list packages
4379 that would be found together with this one in all but
4380 unusual installations.
4384 <tag><tt>Suggests</tt></tag>
4386 This is used to declare that one package may be more
4387 useful with one or more others. Using this field
4388 tells the packaging system and the user that the
4389 listed packages are related to this one and can
4390 perhaps enhance its usefulness, but that installing
4391 this one without them is perfectly reasonable.
4394 <tag><tt>Enhances</tt></tag>
4396 This field is similar to Suggests but works in the
4397 opposite direction. It is used to declare that a
4398 package can enhance the functionality of another
4402 <tag><tt>Pre-Depends</tt></tag>
4405 This field is like <tt>Depends</tt>, except that it
4406 also forces <prgn>dpkg</prgn> to complete installation
4407 of the packages named before even starting the
4408 installation of the package which declares the
4409 pre-dependency, as follows:
4413 When a package declaring a pre-dependency is about to
4414 be <em>unpacked</em> the pre-dependency can be
4415 satisfied if the depended-on package is either fully
4416 configured, <em>or even if</em> the depended-on
4417 package(s) are only unpacked or half-configured,
4418 provided that they have been configured correctly at
4419 some point in the past (and not removed or partially
4420 removed since). In this case, both the
4421 previously-configured and currently unpacked or
4422 half-configured versions must satisfy any version
4423 clause in the <tt>Pre-Depends</tt> field.
4427 When the package declaring a pre-dependency is about
4428 to be <em>configured</em>, the pre-dependency will be
4429 treated as a normal <tt>Depends</tt>, that is, it will
4430 be considered satisfied only if the depended-on
4431 package has been correctly configured.
4435 <tt>Pre-Depends</tt> should be used sparingly,
4436 preferably only by packages whose premature upgrade or
4437 installation would hamper the ability of the system to
4438 continue with any upgrade that might be in progress.
4442 <tt>Pre-Depends</tt> are also required if the
4443 <prgn>preinst</prgn> script depends on the named
4444 package. It is best to avoid this situation if
4452 When selecting which level of dependency to use you should
4453 consider how important the depended-on package is to the
4454 functionality of the one declaring the dependency. Some
4455 packages are composed of components of varying degrees of
4456 importance. Such a package should list using
4457 <tt>Depends</tt> the package(s) which are required by the
4458 more important components. The other components'
4459 requirements may be mentioned as Suggestions or
4460 Recommendations, as appropriate to the components' relative
4466 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4469 When one binary package declares that it breaks another,
4470 <prgn>dpkg</prgn> will refuse to allow the package which
4471 declares <tt>Breaks</tt> be installed unless the broken
4472 package is deconfigured first, and it will refuse to
4473 allow the broken package to be reconfigured.
4477 A package will not be regarded as causing breakage merely
4478 because its configuration files are still installed; it must
4479 be at least half-installed.
4483 A special exception is made for packages which declare that
4484 they break their own package name or a virtual package which
4485 they provide (see below): this does not count as a real
4490 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4491 version clause; such a <tt>Breaks</tt> is introduced in the
4492 version of an (implicit or explicit) dependency which
4493 violates an assumption or reveals a bug in earlier versions
4494 of the broken package. This use of <tt>Breaks</tt> will
4495 inform higher-level package management tools that broken
4496 package must be upgraded before the new one.
4500 If the breaking package also overwrites some files from the
4501 older package, it should use <tt>Replaces</tt> (not
4502 <tt>Conflicts</tt>) to ensure this goes smoothly.
4506 <sect id="conflicts">
4507 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4510 When one binary package declares a conflict with another
4511 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4512 refuse to allow them to be installed on the system at the
4517 If one package is to be installed, the other must be removed
4518 first - if the package being installed is marked as
4519 replacing (see <ref id="replaces">) the one on the system,
4520 or the one on the system is marked as deselected, or both
4521 packages are marked <tt>Essential</tt>, then
4522 <prgn>dpkg</prgn> will automatically remove the package
4523 which is causing the conflict, otherwise it will halt the
4524 installation of the new package with an error. This
4525 mechanism is specifically designed to produce an error when
4526 the installed package is <tt>Essential</tt>, but the new
4531 A package will not cause a conflict merely because its
4532 configuration files are still installed; it must be at least
4537 A special exception is made for packages which declare a
4538 conflict with their own package name, or with a virtual
4539 package which they provide (see below): this does not
4540 prevent their installation, and allows a package to conflict
4541 with others providing a replacement for it. You use this
4542 feature when you want the package in question to be the only
4543 package providing some feature.
4547 A <tt>Conflicts</tt> entry should almost never have an
4548 "earlier than" version clause. This would prevent
4549 <prgn>dpkg</prgn> from upgrading or installing the package
4550 which declared such a conflict until the upgrade or removal
4551 of the conflicted-with package had been completed. Instead,
4552 <tt>Breaks</tt> may be used.
4556 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4560 As well as the names of actual ("concrete") packages, the
4561 package relationship fields <tt>Depends</tt>,
4562 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4563 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4564 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4565 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4566 may mention "virtual packages".
4570 A <em>virtual package</em> is one which appears in the
4571 <tt>Provides</tt> control file field of another package.
4572 The effect is as if the package(s) which provide a
4573 particular virtual package name had been listed by name
4574 everywhere the virtual package name appears. (See also <ref
4579 If there are both concrete and virtual packages of the same
4580 name, then the dependency may be satisfied (or the conflict
4581 caused) by either the concrete package with the name in
4582 question or any other concrete package which provides the
4583 virtual package with the name in question. This is so that,
4584 for example, supposing we have
4585 <example compact="compact">
4588 </example> and someone else releases an enhanced version of
4589 the <tt>bar</tt> package they can say:
4590 <example compact="compact">
4594 and the <tt>bar-plus</tt> package will now also satisfy the
4595 dependency for the <tt>foo</tt> package.
4599 If a relationship field has a version number attached
4600 then only real packages will be considered to see whether
4601 the relationship is satisfied (or the prohibition violated,
4602 for a conflict or breakage) - it is assumed that a real
4603 package which provides the virtual package is not of the
4604 "right" version. So, a <tt>Provides</tt> field may not
4605 contain version numbers, and the version number of the
4606 concrete package which provides a particular virtual package
4607 will not be looked at when considering a dependency on or
4608 conflict with the virtual package name.
4612 It is likely that the ability will be added in a future
4613 release of <prgn>dpkg</prgn> to specify a version number for
4614 each virtual package it provides. This feature is not yet
4615 present, however, and is expected to be used only
4620 If you want to specify which of a set of real packages
4621 should be the default to satisfy a particular dependency on
4622 a virtual package, you should list the real package as an
4623 alternative before the virtual one.
4628 <sect id="replaces"><heading>Overwriting files and replacing
4629 packages - <tt>Replaces</tt></heading>
4632 Packages can declare in their control file that they should
4633 overwrite files in certain other packages, or completely
4634 replace other packages. The <tt>Replaces</tt> control file
4635 field has these two distinct purposes.
4638 <sect1><heading>Overwriting files in other packages</heading>
4641 Firstly, as mentioned before, it is usually an error for a
4642 package to contain files which are on the system in
4647 However, if the overwriting package declares that it
4648 <tt>Replaces</tt> the one containing the file being
4649 overwritten, then <prgn>dpkg</prgn> will replace the file
4650 from the old package with that from the new. The file
4651 will no longer be listed as "owned" by the old package.
4655 If a package is completely replaced in this way, so that
4656 <prgn>dpkg</prgn> does not know of any files it still
4657 contains, it is considered to have "disappeared". It will
4658 be marked as not wanted on the system (selected for
4659 removal) and not installed. Any <tt>conffile</tt>s
4660 details noted for the package will be ignored, as they
4661 will have been taken over by the overwriting package. The
4662 package's <prgn>postrm</prgn> script will be run with a
4663 special argument to allow the package to do any final
4664 cleanup required. See <ref id="mscriptsinstact">.
4667 Replaces is a one way relationship -- you have to
4668 install the replacing package after the replaced
4675 For this usage of <tt>Replaces</tt>, virtual packages (see
4676 <ref id="virtual">) are not considered when looking at a
4677 <tt>Replaces</tt> field - the packages declared as being
4678 replaced must be mentioned by their real names.
4682 Furthermore, this usage of <tt>Replaces</tt> only takes
4683 effect when both packages are at least partially on the
4684 system at once, so that it can only happen if they do not
4685 conflict or if the conflict has been overridden.
4690 <sect1><heading>Replacing whole packages, forcing their
4694 Secondly, <tt>Replaces</tt> allows the packaging system to
4695 resolve which package should be removed when there is a
4696 conflict - see <ref id="conflicts">. This usage only
4697 takes effect when the two packages <em>do</em> conflict,
4698 so that the two usages of this field do not interfere with
4703 In this situation, the package declared as being replaced
4704 can be a virtual package, so for example, all mail
4705 transport agents (MTAs) would have the following fields in
4706 their control files:
4707 <example compact="compact">
4708 Provides: mail-transport-agent
4709 Conflicts: mail-transport-agent
4710 Replaces: mail-transport-agent
4712 ensuring that only one MTA can be installed at any one
4717 <sect id="sourcebinarydeps">
4718 <heading>Relationships between source and binary packages -
4719 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4720 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4724 Source packages that require certain binary packages to be
4725 installed or absent at the time of building the package
4726 can declare relationships to those binary packages.
4730 This is done using the <tt>Build-Depends</tt>,
4731 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4732 <tt>Build-Conflicts-Indep</tt> control file fields.
4736 Build-dependencies on "build-essential" binary packages can be
4737 omitted. Please see <ref id="pkg-relations"> for more information.
4741 The dependencies and conflicts they define must be satisfied
4742 (as defined earlier for binary packages) in order to invoke
4743 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4745 If you make "build-arch" or "binary-arch", you need
4746 Build-Depends. If you make "build-indep" or
4747 "binary-indep", you need Build-Depends and
4748 Build-Depends-Indep. If you make "build" or "binary",
4752 There is no Build-Depends-Arch; this role is essentially
4753 met with Build-Depends. Anyone building the
4754 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4755 is basically assumed to be building the whole package
4756 anyway and so installs all build dependencies. The
4757 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4758 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4759 does not yet know how to check for its existence) and
4760 <tt>binary-arch</tt>.
4763 The purpose of the original split, I recall, was so that
4764 the autobuilders wouldn't need to install extra packages
4765 needed only for the binary-indep targets. But without a
4766 build-arch/build-indep split, this didn't work, since
4767 most of the work is done in the build target, not in the
4773 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4775 The <tt>Build-Depends</tt> and
4776 <tt>Build-Conflicts</tt> fields must be satisfied when
4777 any of the following targets is invoked:
4778 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4779 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4780 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4782 <tag><tt>Build-Depends-Indep</tt>,
4783 <tt>Build-Conflicts-Indep</tt></tag>
4785 The <tt>Build-Depends-Indep</tt> and
4786 <tt>Build-Conflicts-Indep</tt> fields must be
4787 satisfied when any of the following targets is
4788 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4789 <tt>binary</tt> and <tt>binary-indep</tt>.
4799 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4802 Packages containing shared libraries must be constructed with
4803 a little care to make sure that the shared library is always
4804 available. This is especially important for packages whose
4805 shared libraries are vitally important, such as the C library
4806 (currently <tt>libc6</tt>).
4810 Packages involving shared libraries should be split up into
4811 several binary packages. This section mostly deals with how
4812 this separation is to be accomplished; rules for files within
4813 the shared library packages are in <ref id="libraries"> instead.
4816 <sect id="sharedlibs-runtime">
4817 <heading>Run-time shared libraries</heading>
4820 The run-time shared library needs to be placed in a package
4821 whose name changes whenever the shared object version
4824 Since it is common place to install several versions of a
4825 package that just provides shared libraries, it is a
4826 good idea that the library package should not
4827 contain any extraneous non-versioned files, unless they
4828 happen to be in versioned directories.</p>
4830 The most common mechanism is to place it in a package
4832 <package><var>libraryname</var><var>soversion</var></package>,
4833 where <file><var>soversion</var></file> is the version number
4834 in the soname of the shared library<footnote>
4835 The soname is the shared object name: it's the thing
4836 that has to match exactly between building an executable
4837 and running it for the dynamic linker to be able run the
4838 program. For example, if the soname of the library is
4839 <file>libfoo.so.6</file>, the library package would be
4840 called <file>libfoo6</file>.
4842 Alternatively, if it would be confusing to directly append
4843 <var>soversion</var> to <var>libraryname</var> (e.g. because
4844 <var>libraryname</var> itself ends in a number), you may use
4845 <package><var>libraryname</var>-<var>soversion</var></package> and
4846 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4851 If you have several shared libraries built from the same
4852 source tree you may lump them all together into a single
4853 shared library package, provided that you change all of
4854 their sonames at once (so that you don't get filename
4855 clashes if you try to install different versions of the
4856 combined shared libraries package).
4860 The package should install the shared libraries under
4861 their normal names. For example, the <package>libgdbm3</package>
4862 package should install <file>libgdbm.so.3.0.0</file> as
4863 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4864 renamed or re-linked by any <prgn>prerm</prgn> or
4865 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4866 of renaming things safely without affecting running programs,
4867 and attempts to interfere with this are likely to lead to
4872 Shared libraries should not be installed executable, since
4873 the dynamic linker does not require this and trying to
4874 execute a shared library usually results in a core dump.
4878 The run-time library package should include the symbolic link that
4879 <prgn>ldconfig</prgn> would create for the shared libraries.
4880 For example, the <package>libgdbm3</package> package should include
4881 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4882 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4883 linker (for example <prgn>ld.so</prgn> or
4884 <prgn>ld-linux.so.*</prgn>) can find the library between the
4885 time that <prgn>dpkg</prgn> installs it and the time that
4886 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4888 The package management system requires the library to be
4889 placed before the symbolic link pointing to it in the
4890 <file>.deb</file> file. This is so that when
4891 <prgn>dpkg</prgn> comes to install the symlink
4892 (overwriting the previous symlink pointing at an older
4893 version of the library), the new shared library is already
4894 in place. In the past, this was achieved by creating the
4895 library in the temporary packaging directory before
4896 creating the symlink. Unfortunately, this was not always
4897 effective, since the building of the tar file in the
4898 <file>.deb</file> depended on the behavior of the underlying
4899 file system. Some file systems (such as reiserfs) reorder
4900 the files so that the order of creation is forgotten.
4901 Since version 1.7.0, <prgn>dpkg</prgn>
4902 reorders the files itself as necessary when building a
4903 package. Thus it is no longer important to concern
4904 oneself with the order of file creation.
4908 <sect1 id="ldconfig">
4909 <heading><tt>ldconfig</tt></heading>
4912 Any package installing shared libraries in one of the default
4913 library directories of the dynamic linker (which are currently
4914 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4915 listed in <file>/etc/ld.so.conf</file><footnote>
4917 <list compact="compact">
4918 <item>/usr/local/lib</item>
4919 <item>/usr/lib/libc5-compat</item>
4920 <item>/lib/libc5-compat</item>
4923 must use <prgn>ldconfig</prgn> to update the shared library
4928 The package maintainer scripts must only call
4929 <prgn>ldconfig</prgn> under these circumstances:
4930 <list compact="compact">
4931 <item>When the <prgn>postinst</prgn> script is run with a
4932 first argument of <tt>configure</tt>, the script must call
4933 <prgn>ldconfig</prgn>, and may optionally invoke
4934 <prgn>ldconfig</prgn> at other times.
4936 <item>When the <prgn>postrm</prgn> script is run with a
4937 first argument of <tt>remove</tt>, the script should call
4938 <prgn>ldconfig</prgn>.
4943 During install or upgrade, the preinst is called before
4944 the new files are installed, so calling "ldconfig" is
4945 pointless. The preinst of an existing package can also be
4946 called if an upgrade fails. However, this happens during
4947 the critical time when a shared libs may exist on-disk
4948 under a temporary name. Thus, it is dangerous and
4949 forbidden by current policy to call "ldconfig" at this
4954 When a package is installed or upgraded, "postinst
4955 configure" runs after the new files are safely on-disk.
4956 Since it is perfectly safe to invoke ldconfig
4957 unconditionally in a postinst, it is OK for a package to
4958 simply put ldconfig in its postinst without checking the
4959 argument. The postinst can also be called to recover from
4960 a failed upgrade. This happens before any new files are
4961 unpacked, so there is no reason to call "ldconfig" at this
4966 For a package that is being removed, prerm is
4967 called with all the files intact, so calling ldconfig is
4968 useless. The other calls to "prerm" happen in the case of
4969 upgrade at a time when all the files of the old package
4970 are on-disk, so again calling "ldconfig" is pointless.
4974 postrm, on the other hand, is called with the "remove"
4975 argument just after the files are removed, so this is
4976 the proper time to call "ldconfig" to notify the system
4977 of the fact that the shared libraries from the package
4978 are removed. The postrm can be called at several other
4979 times. At the time of "postrm purge", "postrm
4980 abort-install", or "postrm abort-upgrade", calling
4981 "ldconfig" is useless because the shared lib files are
4982 not on-disk. However, when "postrm" is invoked with
4983 arguments "upgrade", "failed-upgrade", or "disappear", a
4984 shared lib may exist on-disk under a temporary filename.
4992 <sect id="sharedlibs-support-files">
4993 <heading>Shared library support files</heading>
4996 If your package contains files whose names do not change with
4997 each change in the library shared object version, you must not
4998 put them in the shared library package. Otherwise, several
4999 versions of the shared library cannot be installed at the same
5000 time without filename clashes, making upgrades and transitions
5001 unnecessarily difficult.
5005 It is recommended that supporting files and run-time support
5006 programs that do not need to be invoked manually by users, but
5007 are nevertheless required for the package to function, be placed
5008 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5009 preferably under <file>/usr/lib/</file><var>package-name</var>.
5010 If the program or file is architecture independent, the
5011 recommendation is for it to be placed in a subdirectory of
5012 <file>/usr/share</file> instead, preferably under
5013 <file>/usr/share/</file><var>package-name</var>. Following the
5014 <var>package-name</var> naming convention ensures that the file
5015 names change when the shared object version changes.
5019 Run-time support programs that use the shared library but are
5020 not required for the library to function or files used by the
5021 shared library that can be used by any version of the shared
5022 library package should instead be put in a separate package.
5023 This package might typically be named
5024 <package><var>libraryname</var>-tools</package>; note the
5025 absence of the <var>soversion</var> in the package name.
5029 Files and support programs only useful when compiling software
5030 against the library should be included in the development
5031 package for the library.<footnote>
5032 For example, a <file><var>package-name</var>-config</file>
5033 script or <package>pkg-config</package> configuration files.
5038 <sect id="sharedlibs-static">
5039 <heading>Static libraries</heading>
5042 The static library (<file><var>libraryname.a</var></file>)
5043 is usually provided in addition to the shared version.
5044 It is placed into the development package (see below).
5048 In some cases, it is acceptable for a library to be
5049 available in static form only; these cases include:
5051 <item>libraries for languages whose shared library support
5052 is immature or unstable</item>
5053 <item>libraries whose interfaces are in flux or under
5054 development (commonly the case when the library's
5055 major version number is zero, or where the ABI breaks
5056 across patchlevels)</item>
5057 <item>libraries which are explicitly intended to be
5058 available only in static form by their upstream
5063 <sect id="sharedlibs-dev">
5064 <heading>Development files</heading>
5067 The development files associated to a shared library need to be
5068 placed in a package called
5069 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5070 or if you prefer only to support one development version at a
5071 time, <package><var>libraryname</var>-dev</package>.
5075 In case several development versions of a library exist, you may
5076 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5077 <ref id="conflicts">) to ensure that the user only installs one
5078 development version at a time (as different development versions are
5079 likely to have the same header files in them, which would cause a
5080 filename clash if both were installed).
5084 The development package should contain a symlink for the associated
5085 shared library without a version number. For example, the
5086 <package>libgdbm-dev</package> package should include a symlink
5087 from <file>/usr/lib/libgdbm.so</file> to
5088 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5089 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5090 <file>libgdbm.so</file> when compiling dynamically.
5094 <sect id="sharedlibs-intradeps">
5095 <heading>Dependencies between the packages of the same library</heading>
5098 Typically the development version should have an exact
5099 version dependency on the runtime library, to make sure that
5100 compilation and linking happens correctly. The
5101 <tt>${binary:Version}</tt> substitution variable can be
5102 useful for this purpose.
5104 Previously, <tt>${Source-Version}</tt> was used, but its name
5105 was confusing and it has been deprecated since dpkg 1.13.19.
5110 <sect id="sharedlibs-shlibdeps">
5111 <heading>Dependencies between the library and other packages -
5112 the <tt>shlibs</tt> system</heading>
5115 If a package contains a binary or library which links to a
5116 shared library, we must ensure that when the package is
5117 installed on the system, all of the libraries needed are
5118 also installed. This requirement led to the creation of the
5119 <tt>shlibs</tt> system, which is very simple in its design:
5120 any package which <em>provides</em> a shared library also
5121 provides information on the package dependencies required to
5122 ensure the presence of this library, and any package which
5123 <em>uses</em> a shared library uses this information to
5124 determine the dependencies it requires. The files which
5125 contain the mapping from shared libraries to the necessary
5126 dependency information are called <file>shlibs</file> files.
5130 Thus, when a package is built which contains any shared
5131 libraries, it must provide a <file>shlibs</file> file for other
5132 packages to use, and when a package is built which contains
5133 any shared libraries or compiled binaries, it must run
5134 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5135 on these to determine the libraries used and hence the
5136 dependencies needed by this package.<footnote>
5138 In the past, the shared libraries linked to were
5139 determined by calling <prgn>ldd</prgn>, but now
5140 <prgn>objdump</prgn> is used to do this. The only
5141 change this makes to package building is that
5142 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5143 libraries, whereas in the past this was unnecessary.
5144 The rest of this footnote explains the advantage that
5149 We say that a binary <tt>foo</tt> <em>directly</em> uses
5150 a library <tt>libbar</tt> if it is explicitly linked
5151 with that library (that is, it uses the flag
5152 <tt>-lbar</tt> during the linking stage). Other
5153 libraries that are needed by <tt>libbar</tt> are linked
5154 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5155 linker will load them automatically when it loads
5156 <tt>libbar</tt>. A package should depend on
5157 the libraries it directly uses, and the dependencies for
5158 those libraries should automatically pull in the other
5163 Unfortunately, the <prgn>ldd</prgn> program shows both
5164 the directly and indirectly used libraries, meaning that
5165 the dependencies determined included both direct and
5166 indirect dependencies. The use of <prgn>objdump</prgn>
5167 avoids this problem by determining only the directly
5172 A good example of where this helps is the following. We
5173 could update <tt>libimlib</tt> with a new version that
5174 supports a new graphics format called dgf (but retaining
5175 the same major version number). If we used the old
5176 <prgn>ldd</prgn> method, every package that uses
5177 <tt>libimlib</tt> would need to be recompiled so it
5178 would also depend on <tt>libdgf</tt> or it wouldn't run
5179 due to missing symbols. However with the new system,
5180 packages using <tt>libimlib</tt> can rely on
5181 <tt>libimlib</tt> itself having the dependency on
5182 <tt>libdgf</tt> and so they would not need rebuilding.
5188 In the following sections, we will first describe where the
5189 various <tt>shlibs</tt> files are to be found, then how to
5190 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5191 file format and how to create them if your package contains a
5196 <heading>The <tt>shlibs</tt> files present on the system</heading>
5199 There are several places where <tt>shlibs</tt> files are
5200 found. The following list gives them in the order in which
5202 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5203 (The first one which gives the required information is used.)
5209 <p><file>debian/shlibs.local</file></p>
5212 This lists overrides for this package. Its use is
5213 described below (see <ref id="shlibslocal">).
5218 <p><file>/etc/dpkg/shlibs.override</file></p>
5221 This lists global overrides. This list is normally
5222 empty. It is maintained by the local system
5228 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5231 When packages are being built, any
5232 <file>debian/shlibs</file> files are copied into the
5233 control file area of the temporary build directory and
5234 given the name <file>shlibs</file>. These files give
5235 details of any shared libraries included in the
5237 An example may help here. Let us say that the
5238 source package <tt>foo</tt> generates two binary
5239 packages, <tt>libfoo2</tt> and
5240 <tt>foo-runtime</tt>. When building the binary
5241 packages, the two packages are created in the
5242 directories <file>debian/libfoo2</file> and
5243 <file>debian/foo-runtime</file> respectively.
5244 (<file>debian/tmp</file> could be used instead of one
5245 of these.) Since <tt>libfoo2</tt> provides the
5246 <tt>libfoo</tt> shared library, it will require a
5247 <tt>shlibs</tt> file, which will be installed in
5248 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5250 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5251 when <prgn>dpkg-shlibdeps</prgn> is run on the
5253 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5255 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5256 determine whether <tt>foo-prog</tt>'s library
5257 dependencies are satisfied by any of the libraries
5258 provided by <tt>libfoo2</tt>. For this reason,
5259 <prgn>dpkg-shlibdeps</prgn> must only be run once
5260 all of the individual binary packages'
5261 <tt>shlibs</tt> files have been installed into the
5268 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5271 These are the <file>shlibs</file> files corresponding to
5272 all of the packages installed on the system, and are
5273 maintained by the relevant package maintainers.
5278 <p><file>/etc/dpkg/shlibs.default</file></p>
5281 This file lists any shared libraries whose packages
5282 have failed to provide correct <file>shlibs</file> files.
5283 It was used when the <file>shlibs</file> setup was first
5284 introduced, but it is now normally empty. It is
5285 maintained by the <tt>dpkg</tt> maintainer.
5293 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5294 <file>shlibs</file> files</heading>
5298 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5299 into your <file>debian/rules</file> file. If your package
5300 contains only compiled binaries and libraries (but no scripts),
5301 you can use a command such as:
5302 <example compact="compact">
5303 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5304 debian/tmp/usr/lib/*
5306 Otherwise, you will need to explicitly list the compiled
5307 binaries and libraries.<footnote>
5308 If you are using <tt>debhelper</tt>, the
5309 <prgn>dh_shlibdeps</prgn> program will do this work for
5310 you. It will also correctly handle multi-binary
5316 This command puts the dependency information into the
5317 <file>debian/substvars</file> file, which is then used by
5318 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5319 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5320 field in the control file for this to work.
5324 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5325 done. If it does complain you might need to create your own
5326 <file>debian/shlibs.local</file> file, as explained below (see
5327 <ref id="shlibslocal">).
5331 If you have multiple binary packages, you will need to call
5332 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5333 compiled libraries or binaries. In such a case, you will
5334 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5335 utilities to specify a different <file>substvars</file> file.
5339 If you are creating a udeb for use in the Debian Installer,
5340 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5341 should use the dependency line of type <tt>udeb</tt> by
5342 adding the <tt>-tudeb</tt> option<footnote>
5343 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5344 will automatically add this option if it knows it is
5346 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5347 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5348 fall back to the regular dependency line.
5352 For more details on dpkg-shlibdeps, please see
5353 <ref id="pkg-dpkg-shlibdeps"> and
5354 <manref name="dpkg-shlibdeps" section="1">.
5359 <heading>The <file>shlibs</file> File Format</heading>
5362 Each <file>shlibs</file> file has the same format. Lines
5363 beginning with <tt>#</tt> are considered to be comments and
5364 are ignored. Each line is of the form:
5365 <example compact="compact">
5366 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5371 We will explain this by reference to the example of the
5372 <tt>zlib1g</tt> package, which (at the time of writing)
5373 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5377 <var>type</var> is an optional element that indicates the type
5378 of package for which the line is valid. The only type currently
5379 in use is <tt>udeb</tt>. The colon and space after the type are
5384 <var>library-name</var> is the name of the shared library,
5385 in this case <tt>libz</tt>. (This must match the name part
5386 of the soname, see below.)
5390 <var>soname-version</var> is the version part of the soname of
5391 the library. The soname is the thing that must exactly match
5392 for the library to be recognized by the dynamic linker, and is
5394 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5395 example, <tt>libz.so.1</tt>.<footnote>
5396 This can be determined using the command
5397 <example compact="compact">
5398 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5401 The version part is the part which comes after
5402 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5406 <var>dependencies</var> has the same syntax as a dependency
5407 field in a binary package control file. It should give
5408 details of which packages are required to satisfy a binary
5409 built against the version of the library contained in the
5410 package. See <ref id="depsyntax"> for details.
5414 In our example, if the first version of the <tt>zlib1g</tt>
5415 package which contained a minor number of at least
5416 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5417 <tt>shlibs</tt> entry for this library could say:
5418 <example compact="compact">
5419 libz 1 zlib1g (>= 1:1.1.3)
5421 The version-specific dependency is to avoid warnings from
5422 the dynamic linker about using older shared libraries with
5427 As zlib1g also provides a udeb containing the shared library,
5428 there would also be a second line:
5429 <example compact="compact">
5430 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5436 <heading>Providing a <file>shlibs</file> file</heading>
5439 If your package provides a shared library, you need to create
5440 a <file>shlibs</file> file following the format described above.
5441 It is usual to call this file <file>debian/shlibs</file> (but if
5442 you have multiple binary packages, you might want to call it
5443 <file>debian/shlibs.<var>package</var></file> instead). Then
5444 let <file>debian/rules</file> install it in the control area:
5445 <example compact="compact">
5446 install -m644 debian/shlibs debian/tmp/DEBIAN
5448 or, in the case of a multi-binary package:
5449 <example compact="compact">
5450 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5452 An alternative way of doing this is to create the
5453 <file>shlibs</file> file in the control area directly from
5454 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5455 file at all,<footnote>
5456 This is what <prgn>dh_makeshlibs</prgn> in the
5457 <tt>debhelper</tt> suite does. If your package also has a udeb
5458 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5459 automatically generate the <tt>udeb:</tt> lines if you specify
5460 the name of the udeb with the <tt>--add-udeb</tt> option.
5462 since the <file>debian/shlibs</file> file itself is ignored by
5463 <prgn>dpkg-shlibdeps</prgn>.
5467 As <prgn>dpkg-shlibdeps</prgn> reads the
5468 <file>DEBIAN/shlibs</file> files in all of the binary packages
5469 being built from this source package, all of the
5470 <file>DEBIAN/shlibs</file> files should be installed before
5471 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5476 <sect1 id="shlibslocal">
5477 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5480 This file is intended only as a <em>temporary</em> fix if
5481 your binaries or libraries depend on a library whose package
5482 does not yet provide a correct <file>shlibs</file> file.
5486 We will assume that you are trying to package a binary
5487 <tt>foo</tt>. When you try running
5488 <prgn>dpkg-shlibdeps</prgn> you get the following error
5489 message (<tt>-O</tt> displays the dependency information on
5490 <tt>stdout</tt> instead of writing it to
5491 <tt>debian/substvars</tt>, and the lines have been wrapped
5492 for ease of reading):
5493 <example compact="compact">
5494 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5495 dpkg-shlibdeps: warning: unable to find dependency
5496 information for shared library libbar (soname 1,
5497 path /usr/lib/libbar.so.1, dependency field Depends)
5498 shlibs:Depends=libc6 (>= 2.2.2-2)
5500 You can then run <prgn>ldd</prgn> on the binary to find the
5501 full location of the library concerned:
5502 <example compact="compact">
5504 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5505 libc.so.6 => /lib/libc.so.6 (0x40032000)
5506 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5508 So the <prgn>foo</prgn> binary depends on the
5509 <prgn>libbar</prgn> shared library, but no package seems to
5510 provide a <file>*.shlibs</file> file handling
5511 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5512 determine the package responsible:
5513 <example compact="compact">
5514 $ dpkg -S /usr/lib/libbar.so.1
5515 bar1: /usr/lib/libbar.so.1
5516 $ dpkg -s bar1 | grep Version
5519 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5520 is the one we are using. Now we can file a bug against the
5521 <tt>bar1</tt> package and create our own
5522 <file>debian/shlibs.local</file> to locally fix the problem.
5523 Including the following line into your
5524 <file>debian/shlibs.local</file> file:
5525 <example compact="compact">
5526 libbar 1 bar1 (>= 1.0-1)
5528 should allow the package build to work.
5532 As soon as the maintainer of <tt>bar1</tt> provides a
5533 correct <file>shlibs</file> file, you should remove this line
5534 from your <file>debian/shlibs.local</file> file. (You should
5535 probably also then have a versioned <tt>Build-Depends</tt>
5536 on <tt>bar1</tt> to help ensure that others do not have the
5537 same problem building your package.)
5546 <chapt id="opersys"><heading>The Operating System</heading>
5549 <heading>File system hierarchy</heading>
5553 <heading>File System Structure</heading>
5556 The location of all installed files and directories must
5557 comply with the Filesystem Hierarchy Standard (FHS),
5558 version 2.3, with the exceptions noted below, and except
5559 where doing so would violate other terms of Debian
5560 Policy. The following exceptions to the FHS apply:
5565 The optional rules related to user specific
5566 configuration files for applications are stored in
5567 the user's home directory are relaxed. It is
5568 recommended that such files start with the
5569 '<tt>.</tt>' character (a "dot file"), and if an
5570 application needs to create more than one dot file
5571 then the preferred placement is in a subdirectory
5572 with a name starting with a '.' character, (a "dot
5573 directory"). In this case it is recommended the
5574 configuration files not start with the '.'
5580 The requirement for amd64 to use <file>/lib64</file>
5581 for 64 bit binaries is removed.
5586 The requirement for object files, internal binaries, and
5587 libraries, including <file>libc.so.*</file>, to be located
5588 directly under <file>/lib{,32}</file> and
5589 <file>/usr/lib{,32}</file> is amended, permitting files
5590 to instead be installed to
5591 <file>/lib/<var>triplet</var></file> and
5592 <file>/usr/lib/<var>triplet</var></file>, where
5593 <tt><var>triplet</var></tt> is the value returned by
5594 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5595 architecture of the package. Packages may <em>not</em>
5596 install files to any <var>triplet</var> path other
5597 than the one matching the architecture of that package;
5598 for instance, an <tt>Architecture: amd64</tt> package
5599 containing 32-bit x86 libraries may not install these
5600 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5602 This is necessary in order to reserve the directories for
5603 use in cross-installation of library packages from other
5604 architectures, as part of the planned deployment of
5609 Applications may also use a single subdirectory under
5610 <file>/usr/lib/<var>triplet</var></file>.
5613 The execution time linker/loader, ld*, must still be made
5614 available in the existing location under /lib or /lib64
5615 since this is part of the ELF ABI for the architecture.
5620 The requirement that
5621 <file>/usr/local/share/man</file> be "synonymous"
5622 with <file>/usr/local/man</file> is relaxed to a
5627 The requirement that windowmanagers with a single
5628 configuration file call it <file>system.*wmrc</file>
5629 is removed, as is the restriction that the window
5630 manager subdirectory be named identically to the
5631 window manager name itself.
5636 The requirement that boot manager configuration
5637 files live in <file>/etc</file>, or at least are
5638 symlinked there, is relaxed to a recommendation.
5645 The version of this document referred here can be
5646 found in the <tt>debian-policy</tt> package or on <url
5647 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5648 name="FHS (Debian copy)"> alongside this manual (or, if
5649 you have the <package>debian-policy</package> installed,
5651 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5652 (local copy)">). The
5653 latest version, which may be a more recent version, may
5655 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5656 Specific questions about following the standard may be
5657 asked on the <tt>debian-devel</tt> mailing list, or
5658 referred to the FHS mailing list (see the
5659 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5665 <heading>Site-specific programs</heading>
5668 As mandated by the FHS, packages must not place any
5669 files in <file>/usr/local</file>, either by putting them in
5670 the file system archive to be unpacked by <prgn>dpkg</prgn>
5671 or by manipulating them in their maintainer scripts.
5675 However, the package may create empty directories below
5676 <file>/usr/local</file> so that the system administrator knows
5677 where to place site-specific files. These are not
5678 directories <em>in</em> <file>/usr/local</file>, but are
5679 children of directories in <file>/usr/local</file>. These
5680 directories (<file>/usr/local/*/dir/</file>)
5681 should be removed on package removal if they are
5686 Note that this applies only to
5687 directories <em>below</em> <file>/usr/local</file>,
5688 not <em>in</em> <file>/usr/local</file>. Packages must
5689 not create sub-directories in the
5690 directory <file>/usr/local</file> itself, except those
5691 listed in FHS, section 4.5. However, you may create
5692 directories below them as you wish. You must not remove
5693 any of the directories listed in 4.5, even if you created
5698 Since <file>/usr/local</file> can be mounted read-only from a
5699 remote server, these directories must be created and
5700 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5701 maintainer scripts and not be included in the
5702 <file>.deb</file> archive. These scripts must not fail if
5703 either of these operations fail.
5707 For example, the <tt>emacsen-common</tt> package could
5708 contain something like
5709 <example compact="compact">
5710 if [ ! -e /usr/local/share/emacs ]
5712 if mkdir /usr/local/share/emacs 2>/dev/null
5714 chown root:staff /usr/local/share/emacs
5715 chmod 2775 /usr/local/share/emacs
5719 in its <prgn>postinst</prgn> script, and
5720 <example compact="compact">
5721 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5722 rmdir /usr/local/share/emacs 2>/dev/null || true
5724 in the <prgn>prerm</prgn> script. (Note that this form is
5725 used to ensure that if the script is interrupted, the
5726 directory <file>/usr/local/share/emacs</file> will still be
5731 If you do create a directory in <file>/usr/local</file> for
5732 local additions to a package, you should ensure that
5733 settings in <file>/usr/local</file> take precedence over the
5734 equivalents in <file>/usr</file>.
5738 However, because <file>/usr/local</file> and its contents are
5739 for exclusive use of the local administrator, a package
5740 must not rely on the presence or absence of files or
5741 directories in <file>/usr/local</file> for normal operation.
5745 The <file>/usr/local</file> directory itself and all the
5746 subdirectories created by the package should (by default) have
5747 permissions 2775 (group-writable and set-group-id) and be
5748 owned by <tt>root:staff</tt>.
5753 <heading>The system-wide mail directory</heading>
5755 The system-wide mail directory
5756 is <file>/var/mail</file>. This directory is part of the
5757 base system and should not be owned by any particular mail
5758 agents. The use of the old
5759 location <file>/var/spool/mail</file> is deprecated, even
5760 though the spool may still be physically located there.
5766 <heading>Users and groups</heading>
5769 <heading>Introduction</heading>
5771 The Debian system can be configured to use either plain or
5776 Some user ids (UIDs) and group ids (GIDs) are reserved
5777 globally for use by certain packages. Because some
5778 packages need to include files which are owned by these
5779 users or groups, or need the ids compiled into binaries,
5780 these ids must be used on any Debian system only for the
5781 purpose for which they are allocated. This is a serious
5782 restriction, and we should avoid getting in the way of
5783 local administration policies. In particular, many sites
5784 allocate users and/or local system groups starting at 100.
5788 Apart from this we should have dynamically allocated ids,
5789 which should by default be arranged in some sensible
5790 order, but the behavior should be configurable.
5794 Packages other than <tt>base-passwd</tt> must not modify
5795 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5796 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5801 <heading>UID and GID classes</heading>
5803 The UID and GID numbers are divided into classes as
5809 Globally allocated by the Debian project, the same
5810 on every Debian system. These ids will appear in
5811 the <file>passwd</file> and <file>group</file> files of all
5812 Debian systems, new ids in this range being added
5813 automatically as the <tt>base-passwd</tt> package is
5818 Packages which need a single statically allocated
5819 uid or gid should use one of these; their
5820 maintainers should ask the <tt>base-passwd</tt>
5828 Dynamically allocated system users and groups.
5829 Packages which need a user or group, but can have
5830 this user or group allocated dynamically and
5831 differently on each system, should use <tt>adduser
5832 --system</tt> to create the group and/or user.
5833 <prgn>adduser</prgn> will check for the existence of
5834 the user or group, and if necessary choose an unused
5835 id based on the ranges specified in
5836 <file>adduser.conf</file>.
5840 <tag>1000-29999:</tag>
5843 Dynamically allocated user accounts. By default
5844 <prgn>adduser</prgn> will choose UIDs and GIDs for
5845 user accounts in this range, though
5846 <file>adduser.conf</file> may be used to modify this
5851 <tag>30000-59999:</tag>
5856 <tag>60000-64999:</tag>
5859 Globally allocated by the Debian project, but only
5860 created on demand. The ids are allocated centrally
5861 and statically, but the actual accounts are only
5862 created on users' systems on demand.
5866 These ids are for packages which are obscure or
5867 which require many statically-allocated ids. These
5868 packages should check for and create the accounts in
5869 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5870 <prgn>adduser</prgn> if it has this facility) if
5871 necessary. Packages which are likely to require
5872 further allocations should have a "hole" left after
5873 them in the allocation, to give them room to
5878 <tag>65000-65533:</tag>
5886 User <tt>nobody</tt>. The corresponding gid refers
5887 to the group <tt>nogroup</tt>.
5894 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5895 not</em> be used, because it is the error return
5904 <sect id="sysvinit">
5905 <heading>System run levels and <file>init.d</file> scripts</heading>
5907 <sect1 id="/etc/init.d">
5908 <heading>Introduction</heading>
5911 The <file>/etc/init.d</file> directory contains the scripts
5912 executed by <prgn>init</prgn> at boot time and when the
5913 init state (or "runlevel") is changed (see <manref
5914 name="init" section="8">).
5918 There are at least two different, yet functionally
5919 equivalent, ways of handling these scripts. For the sake
5920 of simplicity, this document describes only the symbolic
5921 link method. However, it must not be assumed by maintainer
5922 scripts that this method is being used, and any automated
5923 manipulation of the various runlevel behaviors by
5924 maintainer scripts must be performed using
5925 <prgn>update-rc.d</prgn> as described below and not by
5926 manually installing or removing symlinks. For information
5927 on the implementation details of the other method,
5928 implemented in the <tt>file-rc</tt> package, please refer
5929 to the documentation of that package.
5933 These scripts are referenced by symbolic links in the
5934 <file>/etc/rc<var>n</var>.d</file> directories. When changing
5935 runlevels, <prgn>init</prgn> looks in the directory
5936 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
5937 execute, where <tt><var>n</var></tt> is the runlevel that
5938 is being changed to, or <tt>S</tt> for the boot-up
5943 The names of the links all have the form
5944 <file>S<var>mm</var><var>script</var></file> or
5945 <file>K<var>mm</var><var>script</var></file> where
5946 <var>mm</var> is a two-digit number and <var>script</var>
5947 is the name of the script (this should be the same as the
5948 name of the actual script in <file>/etc/init.d</file>).
5952 When <prgn>init</prgn> changes runlevel first the targets
5953 of the links whose names start with a <tt>K</tt> are
5954 executed, each with the single argument <tt>stop</tt>,
5955 followed by the scripts prefixed with an <tt>S</tt>, each
5956 with the single argument <tt>start</tt>. (The links are
5957 those in the <file>/etc/rc<var>n</var>.d</file> directory
5958 corresponding to the new runlevel.) The <tt>K</tt> links
5959 are responsible for killing services and the <tt>S</tt>
5960 link for starting services upon entering the runlevel.
5964 For example, if we are changing from runlevel 2 to
5965 runlevel 3, init will first execute all of the <tt>K</tt>
5966 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
5967 all of the <tt>S</tt> prefixed scripts in that directory.
5968 The links starting with <tt>K</tt> will cause the
5969 referred-to file to be executed with an argument of
5970 <tt>stop</tt>, and the <tt>S</tt> links with an argument
5975 The two-digit number <var>mm</var> is used to determine
5976 the order in which to run the scripts: low-numbered links
5977 have their scripts run first. For example, the
5978 <tt>K20</tt> scripts will be executed before the
5979 <tt>K30</tt> scripts. This is used when a certain service
5980 must be started before another. For example, the name
5981 server <prgn>bind</prgn> might need to be started before
5982 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
5983 can set up its access lists. In this case, the script
5984 that starts <prgn>bind</prgn> would have a lower number
5985 than the script that starts <prgn>inn</prgn> so that it
5987 <example compact="compact">
5994 The two runlevels 0 (halt) and 6 (reboot) are slightly
5995 different. In these runlevels, the links with an
5996 <tt>S</tt> prefix are still called after those with a
5997 <tt>K</tt> prefix, but they too are called with the single
5998 argument <tt>stop</tt>.
6003 <heading>Writing the scripts</heading>
6006 Packages that include daemons for system services should
6007 place scripts in <file>/etc/init.d</file> to start or stop
6008 services at boot time or during a change of runlevel.
6009 These scripts should be named
6010 <file>/etc/init.d/<var>package</var></file>, and they should
6011 accept one argument, saying what to do:
6014 <tag><tt>start</tt></tag>
6015 <item>start the service,</item>
6017 <tag><tt>stop</tt></tag>
6018 <item>stop the service,</item>
6020 <tag><tt>restart</tt></tag>
6021 <item>stop and restart the service if it's already running,
6022 otherwise start the service</item>
6024 <tag><tt>reload</tt></tag>
6025 <item><p>cause the configuration of the service to be
6026 reloaded without actually stopping and restarting
6029 <tag><tt>force-reload</tt></tag>
6030 <item>cause the configuration to be reloaded if the
6031 service supports this, otherwise restart the
6035 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6036 <tt>force-reload</tt> options should be supported by all
6037 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6042 The <file>init.d</file> scripts must ensure that they will
6043 behave sensibly (i.e., returning success and not starting
6044 multiple copies of a service) if invoked with <tt>start</tt>
6045 when the service is already running, or with <tt>stop</tt>
6046 when it isn't, and that they don't kill unfortunately-named
6047 user processes. The best way to achieve this is usually to
6048 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6053 If a service reloads its configuration automatically (as
6054 in the case of <prgn>cron</prgn>, for example), the
6055 <tt>reload</tt> option of the <file>init.d</file> script
6056 should behave as if the configuration has been reloaded
6061 The <file>/etc/init.d</file> scripts must be treated as
6062 configuration files, either (if they are present in the
6063 package, that is, in the .deb file) by marking them as
6064 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6065 by managing them correctly in the maintainer scripts (see
6066 <ref id="config-files">). This is important since we want
6067 to give the local system administrator the chance to adapt
6068 the scripts to the local system, e.g., to disable a
6069 service without de-installing the package, or to specify
6070 some special command line options when starting a service,
6071 while making sure their changes aren't lost during the next
6076 These scripts should not fail obscurely when the
6077 configuration files remain but the package has been
6078 removed, as configuration files remain on the system after
6079 the package has been removed. Only when <prgn>dpkg</prgn>
6080 is executed with the <tt>--purge</tt> option will
6081 configuration files be removed. In particular, as the
6082 <file>/etc/init.d/<var>package</var></file> script itself is
6083 usually a <tt>conffile</tt>, it will remain on the system
6084 if the package is removed but not purged. Therefore, you
6085 should include a <tt>test</tt> statement at the top of the
6087 <example compact="compact">
6088 test -f <var>program-executed-later-in-script</var> || exit 0
6093 Often there are some variables in the <file>init.d</file>
6094 scripts whose values control the behavior of the scripts,
6095 and which a system administrator is likely to want to
6096 change. As the scripts themselves are frequently
6097 <tt>conffile</tt>s, modifying them requires that the
6098 administrator merge in their changes each time the package
6099 is upgraded and the <tt>conffile</tt> changes. To ease
6100 the burden on the system administrator, such configurable
6101 values should not be placed directly in the script.
6102 Instead, they should be placed in a file in
6103 <file>/etc/default</file>, which typically will have the same
6104 base name as the <file>init.d</file> script. This extra file
6105 should be sourced by the script when the script runs. It
6106 must contain only variable settings and comments in SUSv3
6107 <prgn>sh</prgn> format. It may either be a
6108 <tt>conffile</tt> or a configuration file maintained by
6109 the package maintainer scripts. See <ref id="config-files">
6114 To ensure that vital configurable values are always
6115 available, the <file>init.d</file> script should set default
6116 values for each of the shell variables it uses, either
6117 before sourcing the <file>/etc/default/</file> file or
6118 afterwards using something like the <tt>:
6119 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6120 script must behave sensibly and not fail if the
6121 <file>/etc/default</file> file is deleted.
6125 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6126 as temporary filesystems<footnote>
6127 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6128 options in <file>/etc/default/rcS</file>.
6129 </footnote>, so the <file>init.d</file> scripts must handle this
6130 correctly. This will typically amount to creating any required
6131 subdirectories dynamically when the <file>init.d</file> script
6132 is run, rather than including them in the package and relying on
6133 <prgn>dpkg</prgn> to create them.
6138 <heading>Interfacing with the initscript system</heading>
6141 Maintainers should use the abstraction layer provided by
6142 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6143 programs to deal with initscripts in their packages'
6144 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6145 and <prgn>postrm</prgn>.
6149 Directly managing the /etc/rc?.d links and directly
6150 invoking the <file>/etc/init.d/</file> initscripts should
6151 be done only by packages providing the initscript
6152 subsystem (such as <prgn>sysv-rc</prgn> and
6153 <prgn>file-rc</prgn>).
6157 <heading>Managing the links</heading>
6160 The program <prgn>update-rc.d</prgn> is provided for
6161 package maintainers to arrange for the proper creation and
6162 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6163 or their functional equivalent if another method is being
6164 used. This may be used by maintainers in their packages'
6165 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6169 You must not include any <file>/etc/rc<var>n</var>.d</file>
6170 symbolic links in the actual archive or manually create or
6171 remove the symbolic links in maintainer scripts; you must
6172 use the <prgn>update-rc.d</prgn> program instead. (The
6173 former will fail if an alternative method of maintaining
6174 runlevel information is being used.) You must not include
6175 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6176 in the archive either. (Only the <tt>sysvinit</tt>
6181 By default <prgn>update-rc.d</prgn> will start services in
6182 each of the multi-user state runlevels (2, 3, 4, and 5)
6183 and stop them in the halt runlevel (0), the single-user
6184 runlevel (1) and the reboot runlevel (6). The system
6185 administrator will have the opportunity to customize
6186 runlevels by simply adding, moving, or removing the
6187 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6188 symbolic links are being used, or by modifying
6189 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6194 To get the default behavior for your package, put in your
6195 <prgn>postinst</prgn> script
6196 <example compact="compact">
6197 update-rc.d <var>package</var> defaults
6199 and in your <prgn>postrm</prgn>
6200 <example compact="compact">
6201 if [ "$1" = purge ]; then
6202 update-rc.d <var>package</var> remove
6204 </example>. Note that if your package changes runlevels
6205 or priority, you may have to remove and recreate the links,
6206 since otherwise the old links may persist. Refer to the
6207 documentation of <prgn>update-rc.d</prgn>.
6211 This will use a default sequence number of 20. If it does
6212 not matter when or in which order the <file>init.d</file>
6213 script is run, use this default. If it does, then you
6214 should talk to the maintainer of the <prgn>sysvinit</prgn>
6215 package or post to <tt>debian-devel</tt>, and they will
6216 help you choose a number.
6220 For more information about using <tt>update-rc.d</tt>,
6221 please consult its man page <manref name="update-rc.d"
6227 <heading>Running initscripts</heading>
6229 The program <prgn>invoke-rc.d</prgn> is provided to make
6230 it easier for package maintainers to properly invoke an
6231 initscript, obeying runlevel and other locally-defined
6232 constraints that might limit a package's right to start,
6233 stop and otherwise manage services. This program may be
6234 used by maintainers in their packages' scripts.
6238 The package maintainer scripts must use
6239 <prgn>invoke-rc.d</prgn> to invoke the
6240 <file>/etc/init.d/*</file> initscripts, instead of
6241 calling them directly.
6245 By default, <prgn>invoke-rc.d</prgn> will pass any
6246 action requests (start, stop, reload, restart...) to the
6247 <file>/etc/init.d</file> script, filtering out requests
6248 to start or restart a service out of its intended
6253 Most packages will simply need to change:
6254 <example compact="compact">/etc/init.d/<package>
6255 <action></example> in their <prgn>postinst</prgn>
6256 and <prgn>prerm</prgn> scripts to:
6257 <example compact="compact">
6258 if which invoke-rc.d >/dev/null 2>&1; then
6259 invoke-rc.d <var>package</var> <action>
6261 /etc/init.d/<var>package</var> <action>
6267 A package should register its initscript services using
6268 <prgn>update-rc.d</prgn> before it tries to invoke them
6269 using <prgn>invoke-rc.d</prgn>. Invocation of
6270 unregistered services may fail.
6274 For more information about using
6275 <prgn>invoke-rc.d</prgn>, please consult its man page
6276 <manref name="invoke-rc.d" section="8">.
6282 <heading>Boot-time initialization</heading>
6285 There used to be another directory, <file>/etc/rc.boot</file>,
6286 which contained scripts which were run once per machine
6287 boot. This has been deprecated in favour of links from
6288 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6289 described in <ref id="/etc/init.d">. Packages must not
6290 place files in <file>/etc/rc.boot</file>.
6295 <heading>Example</heading>
6298 An example on which you can base your
6299 <file>/etc/init.d</file> scripts is found in
6300 <file>/etc/init.d/skeleton</file>.
6307 <heading>Console messages from <file>init.d</file> scripts</heading>
6310 This section describes the formats to be used for messages
6311 written to standard output by the <file>/etc/init.d</file>
6312 scripts. The intent is to improve the consistency of
6313 Debian's startup and shutdown look and feel. For this
6314 reason, please look very carefully at the details. We want
6315 the messages to have the same format in terms of wording,
6316 spaces, punctuation and case of letters.
6320 Here is a list of overall rules that should be used for
6321 messages generated by <file>/etc/init.d</file> scripts.
6327 The message should fit in one line (fewer than 80
6328 characters), start with a capital letter and end with
6329 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6333 If the script is performing some time consuming task in
6334 the background (not merely starting or stopping a
6335 program, for instance), an ellipsis (three dots:
6336 <tt>...</tt>) should be output to the screen, with no
6337 leading or tailing whitespace or line feeds.
6341 The messages should appear as if the computer is telling
6342 the user what it is doing (politely :-), but should not
6343 mention "it" directly. For example, instead of:
6344 <example compact="compact">
6345 I'm starting network daemons: nfsd mountd.
6347 the message should say
6348 <example compact="compact">
6349 Starting network daemons: nfsd mountd.
6356 <tt>init.d</tt> script should use the following standard
6357 message formats for the situations enumerated below.
6363 <p>When daemons are started</p>
6366 If the script starts one or more daemons, the output
6367 should look like this (a single line, no leading
6369 <example compact="compact">
6370 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6372 The <var>description</var> should describe the
6373 subsystem the daemon or set of daemons are part of,
6374 while <var>daemon-1</var> up to <var>daemon-n</var>
6375 denote each daemon's name (typically the file name of
6380 For example, the output of <file>/etc/init.d/lpd</file>
6382 <example compact="compact">
6383 Starting printer spooler: lpd.
6388 This can be achieved by saying
6389 <example compact="compact">
6390 echo -n "Starting printer spooler: lpd"
6391 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6394 in the script. If there are more than one daemon to
6395 start, the output should look like this:
6396 <example compact="compact">
6397 echo -n "Starting remote file system services:"
6398 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6399 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6400 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6403 This makes it possible for the user to see what is
6404 happening and when the final daemon has been started.
6405 Care should be taken in the placement of white spaces:
6406 in the example above the system administrators can
6407 easily comment out a line if they don't want to start
6408 a specific daemon, while the displayed message still
6414 <p>When a system parameter is being set</p>
6417 If you have to set up different system parameters
6418 during the system boot, you should use this format:
6419 <example compact="compact">
6420 Setting <var>parameter</var> to "<var>value</var>".
6425 You can use a statement such as the following to get
6427 <example compact="compact">
6428 echo "Setting DNS domainname to \"$domainname\"."
6433 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6434 for the left and right quotation marks. A grave accent
6435 (<tt>`</tt>) is not a quote character; neither is an
6436 apostrophe (<tt>'</tt>).
6441 <p>When a daemon is stopped or restarted</p>
6444 When you stop or restart a daemon, you should issue a
6445 message identical to the startup message, except that
6446 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6447 or <tt>Restarting</tt> respectively.
6451 For example, stopping the printer daemon will look like
6453 <example compact="compact">
6454 Stopping printer spooler: lpd.
6460 <p>When something is executed</p>
6463 There are several examples where you have to run a
6464 program at system startup or shutdown to perform a
6465 specific task, for example, setting the system's clock
6466 using <prgn>netdate</prgn> or killing all processes
6467 when the system shuts down. Your message should look
6469 <example compact="compact">
6470 Doing something very useful...done.
6472 You should print the <tt>done.</tt> immediately after
6473 the job has been completed, so that the user is
6474 informed why they have to wait. You can get this
6476 <example compact="compact">
6477 echo -n "Doing something very useful..."
6486 <p>When the configuration is reloaded</p>
6489 When a daemon is forced to reload its configuration
6490 files you should use the following format:
6491 <example compact="compact">
6492 Reloading <var>description</var> configuration...done.
6494 where <var>description</var> is the same as in the
6495 daemon starting message.
6503 <heading>Cron jobs</heading>
6506 Packages must not modify the configuration file
6507 <file>/etc/crontab</file>, and they must not modify the files in
6508 <file>/var/spool/cron/crontabs</file>.</p>
6511 If a package wants to install a job that has to be executed
6512 via cron, it should place a file with the name of the
6513 package in one or more of the following directories:
6514 <example compact="compact">
6520 As these directory names imply, the files within them are
6521 executed on an hourly, daily, weekly, or monthly basis,
6522 respectively. The exact times are listed in
6523 <file>/etc/crontab</file>.</p>
6526 All files installed in any of these directories must be
6527 scripts (e.g., shell scripts or Perl scripts) so that they
6528 can easily be modified by the local system administrator.
6529 In addition, they must be treated as configuration files.
6533 If a certain job has to be executed at some other frequency or
6534 at a specific time, the package should install a file
6535 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6536 same syntax as <file>/etc/crontab</file> and is processed by
6537 <prgn>cron</prgn> automatically. The file must also be
6538 treated as a configuration file. (Note that entries in the
6539 <file>/etc/cron.d</file> directory are not handled by
6540 <prgn>anacron</prgn>. Thus, you should only use this
6541 directory for jobs which may be skipped if the system is not
6545 The scripts or crontab entries in these directories should
6546 check if all necessary programs are installed before they
6547 try to execute them. Otherwise, problems will arise when a
6548 package was removed but not purged since configuration files
6549 are kept on the system in this situation.</p>
6553 <heading>Menus</heading>
6556 The Debian <tt>menu</tt> package provides a standard
6557 interface between packages providing applications and
6558 <em>menu programs</em> (either X window managers or
6559 text-based menu programs such as <prgn>pdmenu</prgn>).
6563 All packages that provide applications that need not be
6564 passed any special command line arguments for normal
6565 operation should register a menu entry for those
6566 applications, so that users of the <tt>menu</tt> package
6567 will automatically get menu entries in their window
6568 managers, as well in shells like <tt>pdmenu</tt>.
6572 Menu entries should follow the current menu policy.
6576 The menu policy can be found in the <tt>menu-policy</tt>
6577 files in the <tt>debian-policy</tt> package.
6578 It is also available from the Debian web mirrors at
6579 <tt><url name="/doc/packaging-manuals/menu-policy/"
6580 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6584 Please also refer to the <em>Debian Menu System</em>
6585 documentation that comes with the <package>menu</package>
6586 package for information about how to register your
6592 <heading>Multimedia handlers</heading>
6595 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6596 is a mechanism for encoding files and data streams and
6597 providing meta-information about them, in particular their
6598 type (e.g. audio or video) and format (e.g. PNG, HTML,
6603 Registration of MIME type handlers allows programs like mail
6604 user agents and web browsers to invoke these handlers to
6605 view, edit or display MIME types they don't support directly.
6609 Packages which provide the ability to view/show/play,
6610 compose, edit or print MIME types should register themselves
6611 as such following the current MIME support policy.
6615 The MIME support policy can be found in the <tt>mime-policy</tt>
6616 files in the <tt>debian-policy</tt> package.
6617 It is also available from the Debian web mirrors at
6618 <tt><url name="/doc/packaging-manuals/mime-policy/"
6619 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6625 <heading>Keyboard configuration</heading>
6628 To achieve a consistent keyboard configuration so that all
6629 applications interpret a keyboard event the same way, all
6630 programs in the Debian distribution must be configured to
6631 comply with the following guidelines.
6635 The following keys must have the specified interpretations:
6638 <tag><tt><--</tt></tag>
6639 <item>delete the character to the left of the cursor</item>
6641 <tag><tt>Delete</tt></tag>
6642 <item>delete the character to the right of the cursor</item>
6644 <tag><tt>Control+H</tt></tag>
6645 <item>emacs: the help prefix</item>
6648 The interpretation of any keyboard events should be
6649 independent of the terminal that is used, be it a virtual
6650 console, an X terminal emulator, an rlogin/telnet session,
6655 The following list explains how the different programs
6656 should be set up to achieve this:
6662 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6666 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6670 X translations are set up to make
6671 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6672 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6673 is the vt220 escape code for the "delete character"
6674 key). This must be done by loading the X resources
6675 using <prgn>xrdb</prgn> on all local X displays, not
6676 using the application defaults, so that the
6677 translation resources used correspond to the
6678 <prgn>xmodmap</prgn> settings.
6682 The Linux console is configured to make
6683 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6684 generate <tt>ESC [ 3 ~</tt>.
6688 X applications are configured so that <tt><</tt>
6689 deletes left, and <tt>Delete</tt> deletes right. Motif
6690 applications already work like this.
6694 Terminals should have <tt>stty erase ^?</tt> .
6698 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6699 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6700 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6704 Emacs is programmed to map <tt>KB_Backspace</tt> or
6705 the <tt>stty erase</tt> character to
6706 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6707 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6708 <tt>^H</tt> to <tt>help</tt> as always.
6712 Other applications use the <tt>stty erase</tt>
6713 character and <tt>kdch1</tt> for the two delete keys,
6714 with ASCII DEL being "delete previous character" and
6715 <tt>kdch1</tt> being "delete character under
6723 This will solve the problem except for the following
6730 Some terminals have a <tt><--</tt> key that cannot
6731 be made to produce anything except <tt>^H</tt>. On
6732 these terminals Emacs help will be unavailable on
6733 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6734 character takes precedence in Emacs, and has been set
6735 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6736 available) can be used instead.
6740 Some operating systems use <tt>^H</tt> for <tt>stty
6741 erase</tt>. However, modern telnet versions and all
6742 rlogin versions propagate <tt>stty</tt> settings, and
6743 almost all UNIX versions honour <tt>stty erase</tt>.
6744 Where the <tt>stty</tt> settings are not propagated
6745 correctly, things can be made to work by using
6746 <tt>stty</tt> manually.
6750 Some systems (including previous Debian versions) use
6751 <prgn>xmodmap</prgn> to arrange for both
6752 <tt><--</tt> and <tt>Delete</tt> to generate
6753 <tt>KB_Delete</tt>. We can change the behavior of
6754 their X clients using the same X resources that we use
6755 to do it for our own clients, or configure our clients
6756 using their resources when things are the other way
6757 around. On displays configured like this
6758 <tt>Delete</tt> will not work, but <tt><--</tt>
6763 Some operating systems have different <tt>kdch1</tt>
6764 settings in their <tt>terminfo</tt> database for
6765 <tt>xterm</tt> and others. On these systems the
6766 <tt>Delete</tt> key will not work correctly when you
6767 log in from a system conforming to our policy, but
6768 <tt><--</tt> will.
6775 <heading>Environment variables</heading>
6778 A program must not depend on environment variables to get
6779 reasonable defaults. (That's because these environment
6780 variables would have to be set in a system-wide
6781 configuration file like <file>/etc/profile</file>, which is not
6782 supported by all shells.)
6786 If a program usually depends on environment variables for its
6787 configuration, the program should be changed to fall back to
6788 a reasonable default configuration if these environment
6789 variables are not present. If this cannot be done easily
6790 (e.g., if the source code of a non-free program is not
6791 available), the program must be replaced by a small
6792 "wrapper" shell script which sets the environment variables
6793 if they are not already defined, and calls the original program.
6797 Here is an example of a wrapper script for this purpose:
6799 <example compact="compact">
6801 BAR=${BAR:-/var/lib/fubar}
6803 exec /usr/lib/foo/foo "$@"
6808 Furthermore, as <file>/etc/profile</file> is a configuration
6809 file of the <prgn>base-files</prgn> package, other packages must
6810 not put any environment variables or other commands into that
6815 <sect id="doc-base">
6816 <heading>Registering Documents using doc-base</heading>
6819 The <package>doc-base</package> package implements a
6820 flexible mechanism for handling and presenting
6821 documentation. The recommended practice is for every Debian
6822 package that provides online documentation (other than just
6823 manual pages) to register these documents with
6824 <package>doc-base</package> by installing a
6825 <package>doc-base</package> control file via the
6826 <prgn/install-docs/ script at installation time and
6827 de-register the manuals again when the package is removed.
6830 Please refer to the documentation that comes with the
6831 <package>doc-base</package> package for information and
6840 <heading>Files</heading>
6843 <heading>Binaries</heading>
6846 Two different packages must not install programs with
6847 different functionality but with the same filenames. (The
6848 case of two programs having the same functionality but
6849 different implementations is handled via "alternatives" or
6850 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6851 <ref id="conflicts"> respectively.) If this case happens,
6852 one of the programs must be renamed. The maintainers should
6853 report this to the <tt>debian-devel</tt> mailing list and
6854 try to find a consensus about which program will have to be
6855 renamed. If a consensus cannot be reached, <em>both</em>
6856 programs must be renamed.
6860 By default, when a package is being built, any binaries
6861 created should include debugging information, as well as
6862 being compiled with optimization. You should also turn on
6863 as many reasonable compilation warnings as possible; this
6864 makes life easier for porters, who can then look at build
6865 logs for possible problems. For the C programming language,
6866 this means the following compilation parameters should be
6868 <example compact="compact">
6870 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
6872 INSTALL = install -s # (or use strip on the files in debian/tmp)
6877 Note that by default all installed binaries should be stripped,
6878 either by using the <tt>-s</tt> flag to
6879 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
6880 the binaries after they have been copied into
6881 <file>debian/tmp</file> but before the tree is made into a
6886 Although binaries in the build tree should be compiled with
6887 debugging information by default, it can often be difficult to
6888 debug programs if they are also subjected to compiler
6889 optimization. For this reason, it is recommended to support the
6890 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
6891 (see <ref id="debianrules-options">). This variable can contain
6892 several flags to change how a package is compiled and built.
6896 It is up to the package maintainer to decide what
6897 compilation options are best for the package. Certain
6898 binaries (such as computationally-intensive programs) will
6899 function better with certain flags (<tt>-O3</tt>, for
6900 example); feel free to use them. Please use good judgment
6901 here. Don't use flags for the sake of it; only use them
6902 if there is good reason to do so. Feel free to override
6903 the upstream author's ideas about which compilation
6904 options are best: they are often inappropriate for our
6910 <sect id="libraries">
6911 <heading>Libraries</heading>
6914 If the package is <strong>architecture: any</strong>, then
6915 the shared library compilation and linking flags must have
6916 <tt>-fPIC</tt>, or the package shall not build on some of
6917 the supported architectures<footnote>
6919 If you are using GCC, <tt>-fPIC</tt> produces code with
6920 relocatable position independent code, which is required for
6921 most architectures to create a shared library, with i386 and
6922 perhaps some others where non position independent code is
6923 permitted in a shared library.
6926 Position independent code may have a performance penalty,
6927 especially on <tt>i386</tt>. However, in most cases the
6928 speed penalty must be measured against the memory wasted on
6929 the few architectures where non position independent code is
6932 </footnote>. Any exception to this rule must be discussed on
6933 the mailing list <em>debian-devel@lists.debian.org</em>, and
6934 a rough consensus obtained. The reasons for not compiling
6935 with <tt>-fPIC</tt> flag must be recorded in the file
6936 <tt>README.Debian</tt>, and care must be taken to either
6937 restrict the architecture or arrange for <tt>-fPIC</tt> to
6938 be used on architectures where it is required.<footnote>
6940 Some of the reasons why this might be required is if the
6941 library contains hand crafted assembly code that is not
6942 relocatable, the speed penalty is excessive for compute
6943 intensive libs, and similar reasons.
6948 As to the static libraries, the common case is not to have
6949 relocatable code, since there is no benefit, unless in specific
6950 cases; therefore the static version must not be compiled
6951 with the <tt>-fPIC</tt> flag. Any exception to this rule
6952 should be discussed on the mailing list
6953 <em>debian-devel@lists.debian.org</em>, and the reasons for
6954 compiling with the <tt>-fPIC</tt> flag must be recorded in
6955 the file <tt>README.Debian</tt>. <footnote>
6957 Some of the reasons for linking static libraries with
6958 the <tt>-fPIC</tt> flag are if, for example, one needs a
6959 Perl API for a library that is under rapid development,
6960 and has an unstable API, so shared libraries are
6961 pointless at this phase of the library's development. In
6962 that case, since Perl needs a library with relocatable
6963 code, it may make sense to create a static library with
6964 relocatable code. Another reason cited is if you are
6965 distilling various libraries into a common shared
6966 library, like <tt>mklibs</tt> does in the Debian
6972 In other words, if both a shared and a static library is
6973 being built, each source unit (<tt>*.c</tt>, for example,
6974 for C files) will need to be compiled twice, for the normal
6978 You must specify the gcc option <tt>-D_REENTRANT</tt>
6979 when building a library (either static or shared) to make
6980 the library compatible with LinuxThreads.
6984 Although not enforced by the build tools, shared libraries
6985 must be linked against all libraries that they use symbols from
6986 in the same way that binaries are. This ensures the correct
6987 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
6988 system and guarantees that all libraries can be safely opened
6989 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
6990 option <tt>-Wl,-z,defs</tt> when building a shared library.
6991 Since this option enforces symbol resolution at build time,
6992 a missing library reference will be caught early as a fatal
6997 All installed shared libraries should be stripped with
6998 <example compact="compact">
6999 strip --strip-unneeded <var>your-lib</var>
7001 (The option <tt>--strip-unneeded</tt> makes
7002 <prgn>strip</prgn> remove only the symbols which aren't
7003 needed for relocation processing.) Shared libraries can
7004 function perfectly well when stripped, since the symbols for
7005 dynamic linking are in a separate part of the ELF object
7007 You might also want to use the options
7008 <tt>--remove-section=.comment</tt> and
7009 <tt>--remove-section=.note</tt> on both shared libraries
7010 and executables, and <tt>--strip-debug</tt> on static
7016 Note that under some circumstances it may be useful to
7017 install a shared library unstripped, for example when
7018 building a separate package to support debugging.
7022 Shared object files (often <file>.so</file> files) that are not
7023 public libraries, that is, they are not meant to be linked
7024 to by third party executables (binaries of other packages),
7025 should be installed in subdirectories of the
7026 <file>/usr/lib</file> directory. Such files are exempt from the
7027 rules that govern ordinary shared libraries, except that
7028 they must not be installed executable and should be
7030 A common example are the so-called "plug-ins",
7031 internal shared objects that are dynamically loaded by
7032 programs using <manref name="dlopen" section="3">.
7037 An ever increasing number of packages are using
7038 <prgn>libtool</prgn> to do their linking. The latest GNU
7039 libtools (>= 1.3a) can take advantage of the metadata in the
7040 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7041 files). The main advantage of <prgn>libtool</prgn>'s
7042 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7043 store and subsequently access metadata with respect to the
7044 libraries it builds. <prgn>libtool</prgn> will search for
7045 those files, which contain a lot of useful information about
7046 a library (such as library dependency information for static
7047 linking). Also, they're <em>essential</em> for programs
7048 using <tt>libltdl</tt>.<footnote>
7049 Although <prgn>libtool</prgn> is fully capable of
7050 linking against shared libraries which don't have
7051 <tt>.la</tt> files, as it is a mere shell script it can
7052 add considerably to the build time of a
7053 <prgn>libtool</prgn>-using package if that shell script
7054 has to derive all this information from first principles
7055 for each library every time it is linked. With the
7056 advent of <prgn>libtool</prgn> version 1.4 (and to a
7057 lesser extent <prgn>libtool</prgn> version 1.3), the
7058 <file>.la</file> files also store information about
7059 inter-library dependencies which cannot necessarily be
7060 derived after the <file>.la</file> file is deleted.
7065 Packages that use <prgn>libtool</prgn> to create shared
7066 libraries should include the <file>.la</file> files in the
7067 <tt>-dev</tt> package, unless the package relies on
7068 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7069 the <tt>.la</tt> files must go in the run-time library
7074 You must make sure that you use only released versions of
7075 shared libraries to build your packages; otherwise other
7076 users will not be able to run your binaries
7077 properly. Producing source packages that depend on
7078 unreleased compilers is also usually a bad
7085 <heading>Shared libraries</heading>
7087 This section has moved to <ref id="sharedlibs">.
7093 <heading>Scripts</heading>
7096 All command scripts, including the package maintainer
7097 scripts inside the package and used by <prgn>dpkg</prgn>,
7098 should have a <tt>#!</tt> line naming the shell to be used
7103 In the case of Perl scripts this should be
7104 <tt>#!/usr/bin/perl</tt>.
7108 When scripts are installed into a directory in the system
7109 PATH, the script name should not include an extension such
7110 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7111 language currently used to implement it.
7114 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
7115 should almost certainly start with <tt>set -e</tt> so that
7116 errors are detected. Every script should use
7117 <tt>set -e</tt> or check the exit status of <em>every</em>
7122 Scripts may assume that <file>/bin/sh</file> implements the
7123 SUSv3 Shell Command Language<footnote>
7124 Single UNIX Specification, version 3, which is also IEEE
7125 1003.1-2004 (POSIX), and is available on the World Wide Web
7126 from <url id="http://www.unix.org/version3/online.html"
7127 name="The Open Group"> after free
7128 registration.</footnote>
7129 plus the following additional features not mandated by
7131 These features are in widespread use in the Linux community
7132 and are implemented in all of bash, dash, and ksh, the most
7133 common shells users may wish to use as <file>/bin/sh</file>.
7136 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7137 must not generate a newline.</item>
7138 <item><tt>test</tt>, if implemented as a shell built-in, must
7139 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7141 <item><tt>local</tt> to create a scoped variable must be
7142 supported, including listing multiple variables in a single
7143 local command and assigning a value to a variable at the
7144 same time as localizing it. <tt>local</tt> may or
7145 may not preserve the variable value from an outer scope if
7146 no assignment is present. Uses such as:
7150 # ... use a, b, c, d ...
7153 must be supported and must set the value of <tt>c</tt> to
7157 If a shell script requires non-SUSv3 features from the shell
7158 interpreter other than those listed above, the appropriate shell
7159 must be specified in the first line of the script (e.g.,
7160 <tt>#!/bin/bash</tt>) and the package must depend on the package
7161 providing the shell (unless the shell package is marked
7162 "Essential", as in the case of <prgn>bash</prgn>).
7166 You may wish to restrict your script to SUSv3 features plus the
7167 above set when possible so that it may use <file>/bin/sh</file>
7168 as its interpreter. If your script works with <prgn>dash</prgn>
7169 (originally called <prgn>ash</prgn>), it probably complies with
7170 the above requirements, but if you are in doubt, use
7171 <file>/bin/bash</file>.
7175 Perl scripts should check for errors when making any
7176 system calls, including <tt>open</tt>, <tt>print</tt>,
7177 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7181 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7182 scripting languages. See <em>Csh Programming Considered
7183 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7184 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7185 If an upstream package comes with <prgn>csh</prgn> scripts
7186 then you must make sure that they start with
7187 <tt>#!/bin/csh</tt> and make your package depend on the
7188 <prgn>c-shell</prgn> virtual package.
7192 Any scripts which create files in world-writeable
7193 directories (e.g., in <file>/tmp</file>) must use a
7194 mechanism which will fail atomically if a file with the same
7195 name already exists.
7199 The Debian base system provides the <prgn>tempfile</prgn>
7200 and <prgn>mktemp</prgn> utilities for use by scripts for
7207 <heading>Symbolic links</heading>
7210 In general, symbolic links within a top-level directory
7211 should be relative, and symbolic links pointing from one
7212 top-level directory into another should be absolute. (A
7213 top-level directory is a sub-directory of the root
7214 directory <file>/</file>.)
7218 In addition, symbolic links should be specified as short as
7219 possible, i.e., link targets like <file>foo/../bar</file> are
7224 Note that when creating a relative link using
7225 <prgn>ln</prgn> it is not necessary for the target of the
7226 link to exist relative to the working directory you're
7227 running <prgn>ln</prgn> from, nor is it necessary to change
7228 directory to the directory where the link is to be made.
7229 Simply include the string that should appear as the target
7230 of the link (this will be a pathname relative to the
7231 directory in which the link resides) as the first argument
7236 For example, in your <prgn>Makefile</prgn> or
7237 <file>debian/rules</file>, you can do things like:
7238 <example compact="compact">
7239 ln -fs gcc $(prefix)/bin/cc
7240 ln -fs gcc debian/tmp/usr/bin/cc
7241 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7242 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7247 A symbolic link pointing to a compressed file should always
7248 have the same file extension as the referenced file. (For
7249 example, if a file <file>foo.gz</file> is referenced by a
7250 symbolic link, the filename of the link has to end with
7251 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7256 <heading>Device files</heading>
7259 Packages must not include device files in the package file
7264 If a package needs any special device files that are not
7265 included in the base system, it must call
7266 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7267 after notifying the user<footnote>
7268 This notification could be done via a (low-priority)
7269 debconf message, or an echo (printf) statement.
7274 Packages must not remove any device files in the
7275 <prgn>postrm</prgn> or any other script. This is left to the
7276 system administrator.
7280 Debian uses the serial devices
7281 <file>/dev/ttyS*</file>. Programs using the old
7282 <file>/dev/cu*</file> devices should be changed to use
7283 <file>/dev/ttyS*</file>.
7287 <sect id="config-files">
7288 <heading>Configuration files</heading>
7291 <heading>Definitions</heading>
7295 <tag>configuration file</tag>
7297 A file that affects the operation of a program, or
7298 provides site- or host-specific information, or
7299 otherwise customizes the behavior of a program.
7300 Typically, configuration files are intended to be
7301 modified by the system administrator (if needed or
7302 desired) to conform to local policy or to provide
7303 more useful site-specific behavior.
7306 <tag><tt>conffile</tt></tag>
7308 A file listed in a package's <tt>conffiles</tt>
7309 file, and is treated specially by <prgn>dpkg</prgn>
7310 (see <ref id="configdetails">).
7316 The distinction between these two is important; they are
7317 not interchangeable concepts. Almost all
7318 <tt>conffile</tt>s are configuration files, but many
7319 configuration files are not <tt>conffiles</tt>.
7323 As noted elsewhere, <file>/etc/init.d</file> scripts,
7324 <file>/etc/default</file> files, scripts installed in
7325 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7326 configuration installed in <file>/etc/cron.d</file> must be
7327 treated as configuration files. In general, any script that
7328 embeds configuration information is de-facto a configuration
7329 file and should be treated as such.
7334 <heading>Location</heading>
7337 Any configuration files created or used by your package
7338 must reside in <file>/etc</file>. If there are several,
7339 consider creating a subdirectory of <file>/etc</file>
7340 named after your package.
7344 If your package creates or uses configuration files
7345 outside of <file>/etc</file>, and it is not feasible to modify
7346 the package to use <file>/etc</file> directly, put the files
7347 in <file>/etc</file> and create symbolic links to those files
7348 from the location that the package requires.
7353 <heading>Behavior</heading>
7356 Configuration file handling must conform to the following
7358 <list compact="compact">
7360 local changes must be preserved during a package
7364 configuration files must be preserved when the
7365 package is removed, and only deleted when the
7372 The easy way to achieve this behavior is to make the
7373 configuration file a <tt>conffile</tt>. This is
7374 appropriate only if it is possible to distribute a default
7375 version that will work for most installations, although
7376 some system administrators may choose to modify it. This
7377 implies that the default version will be part of the
7378 package distribution, and must not be modified by the
7379 maintainer scripts during installation (or at any other
7384 In order to ensure that local changes are preserved
7385 correctly, no package may contain or make hard links to
7386 conffiles.<footnote>
7387 Rationale: There are two problems with hard links.
7388 The first is that some editors break the link while
7389 editing one of the files, so that the two files may
7390 unwittingly become unlinked and different. The second
7391 is that <prgn>dpkg</prgn> might break the hard link
7392 while upgrading <tt>conffile</tt>s.
7397 The other way to do it is via the maintainer scripts. In
7398 this case, the configuration file must not be listed as a
7399 <tt>conffile</tt> and must not be part of the package
7400 distribution. If the existence of a file is required for
7401 the package to be sensibly configured it is the
7402 responsibility of the package maintainer to provide
7403 maintainer scripts which correctly create, update and
7404 maintain the file and remove it on purge. (See <ref
7405 id="maintainerscripts"> for more information.) These
7406 scripts must be idempotent (i.e., must work correctly if
7407 <prgn>dpkg</prgn> needs to re-run them due to errors
7408 during installation or removal), must cope with all the
7409 variety of ways <prgn>dpkg</prgn> can call maintainer
7410 scripts, must not overwrite or otherwise mangle the user's
7411 configuration without asking, must not ask unnecessary
7412 questions (particularly during upgrades), and must
7413 otherwise be good citizens.
7417 The scripts are not required to configure every possible
7418 option for the package, but only those necessary to get
7419 the package running on a given system. Ideally the
7420 sysadmin should not have to do any configuration other
7421 than that done (semi-)automatically by the
7422 <prgn>postinst</prgn> script.
7426 A common practice is to create a script called
7427 <file><var>package</var>-configure</file> and have the
7428 package's <prgn>postinst</prgn> call it if and only if the
7429 configuration file does not already exist. In certain
7430 cases it is useful for there to be an example or template
7431 file which the maintainer scripts use. Such files should
7432 be in <file>/usr/share/<var>package</var></file> or
7433 <file>/usr/lib/<var>package</var></file> (depending on whether
7434 they are architecture-independent or not). There should
7435 be symbolic links to them from
7436 <file>/usr/share/doc/<var>package</var>/examples</file> if
7437 they are examples, and should be perfectly ordinary
7438 <prgn>dpkg</prgn>-handled files (<em>not</em>
7439 configuration files).
7443 These two styles of configuration file handling must
7444 not be mixed, for that way lies madness:
7445 <prgn>dpkg</prgn> will ask about overwriting the file
7446 every time the package is upgraded.
7451 <heading>Sharing configuration files</heading>
7454 Packages which specify the same file as a
7455 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7456 with each other. (This is an instance of the general rule
7457 about not sharing files. Note that neither alternatives
7458 nor diversions are likely to be appropriate in this case;
7459 in particular, <prgn>dpkg</prgn> does not handle diverted
7460 <tt>conffile</tt>s well.)
7464 The maintainer scripts must not alter a <tt>conffile</tt>
7465 of <em>any</em> package, including the one the scripts
7470 If two or more packages use the same configuration file
7471 and it is reasonable for both to be installed at the same
7472 time, one of these packages must be defined as
7473 <em>owner</em> of the configuration file, i.e., it will be
7474 the package which handles that file as a configuration
7475 file. Other packages that use the configuration file must
7476 depend on the owning package if they require the
7477 configuration file to operate. If the other package will
7478 use the configuration file if present, but is capable of
7479 operating without it, no dependency need be declared.
7483 If it is desirable for two or more related packages to
7484 share a configuration file <em>and</em> for all of the
7485 related packages to be able to modify that configuration
7486 file, then the following should be done:
7487 <enumlist compact="compact">
7489 One of the related packages (the "owning" package)
7490 will manage the configuration file with maintainer
7491 scripts as described in the previous section.
7494 The owning package should also provide a program
7495 that the other packages may use to modify the
7499 The related packages must use the provided program
7500 to make any desired modifications to the
7501 configuration file. They should either depend on
7502 the core package to guarantee that the configuration
7503 modifier program is available or accept gracefully
7504 that they cannot modify the configuration file if it
7505 is not. (This is in addition to the fact that the
7506 configuration file may not even be present in the
7513 Sometimes it's appropriate to create a new package which
7514 provides the basic infrastructure for the other packages
7515 and which manages the shared configuration files. (The
7516 <tt>sgml-base</tt> package is a good example.)
7521 <heading>User configuration files ("dotfiles")</heading>
7524 The files in <file>/etc/skel</file> will automatically be
7525 copied into new user accounts by <prgn>adduser</prgn>.
7526 No other program should reference the files in
7527 <file>/etc/skel</file>.
7531 Therefore, if a program needs a dotfile to exist in
7532 advance in <file>$HOME</file> to work sensibly, that dotfile
7533 should be installed in <file>/etc/skel</file> and treated as a
7538 However, programs that require dotfiles in order to
7539 operate sensibly are a bad thing, unless they do create
7540 the dotfiles themselves automatically.
7544 Furthermore, programs should be configured by the Debian
7545 default installation to behave as closely to the upstream
7546 default behavior as possible.
7550 Therefore, if a program in a Debian package needs to be
7551 configured in some way in order to operate sensibly, that
7552 should be done using a site-wide configuration file placed
7553 in <file>/etc</file>. Only if the program doesn't support a
7554 site-wide default configuration and the package maintainer
7555 doesn't have time to add it may a default per-user file be
7556 placed in <file>/etc/skel</file>.
7560 <file>/etc/skel</file> should be as empty as we can make it.
7561 This is particularly true because there is no easy (or
7562 necessarily desirable) mechanism for ensuring that the
7563 appropriate dotfiles are copied into the accounts of
7564 existing users when a package is installed.
7570 <heading>Log files</heading>
7572 Log files should usually be named
7573 <file>/var/log/<var>package</var>.log</file>. If you have many
7574 log files, or need a separate directory for permission
7575 reasons (<file>/var/log</file> is writable only by
7576 <file>root</file>), you should usually create a directory named
7577 <file>/var/log/<var>package</var></file> and place your log
7582 Log files must be rotated occasionally so that they don't
7583 grow indefinitely; the best way to do this is to drop a log
7584 rotation configuration file into the directory
7585 <file>/etc/logrotate.d</file> and use the facilities provided by
7586 logrotate.<footnote>
7588 The traditional approach to log files has been to set up
7589 <em>ad hoc</em> log rotation schemes using simple shell
7590 scripts and cron. While this approach is highly
7591 customizable, it requires quite a lot of sysadmin work.
7592 Even though the original Debian system helped a little
7593 by automatically installing a system which can be used
7594 as a template, this was deemed not enough.
7598 The use of <prgn>logrotate</prgn>, a program developed
7599 by Red Hat, is better, as it centralizes log management.
7600 It has both a configuration file
7601 (<file>/etc/logrotate.conf</file>) and a directory where
7602 packages can drop their individual log rotation
7603 configurations (<file>/etc/logrotate.d</file>).
7606 Here is a good example for a logrotate config
7607 file (for more information see <manref name="logrotate"
7609 <example compact="compact">
7610 /var/log/foo/*.log {
7615 /etc/init.d/foo force-reload
7619 This rotates all files under <file>/var/log/foo</file>, saves 12
7620 compressed generations, and forces the daemon to reload its
7621 configuration information after the log rotation.
7625 Log files should be removed when the package is
7626 purged (but not when it is only removed). This should be
7627 done by the <prgn>postrm</prgn> script when it is called
7628 with the argument <tt>purge</tt> (see <ref
7629 id="removedetails">).
7634 <heading>Permissions and owners</heading>
7637 The rules in this section are guidelines for general use.
7638 If necessary you may deviate from the details below.
7639 However, if you do so you must make sure that what is done
7640 is secure and you should try to be as consistent as possible
7641 with the rest of the system. You should probably also
7642 discuss it on <prgn>debian-devel</prgn> first.
7646 Files should be owned by <tt>root:root</tt>, and made
7647 writable only by the owner and universally readable (and
7648 executable, if appropriate), that is mode 644 or 755.
7652 Directories should be mode 755 or (for group-writability)
7653 mode 2775. The ownership of the directory should be
7654 consistent with its mode: if a directory is mode 2775, it
7655 should be owned by the group that needs write access to
7658 When a package is upgraded, and the owner or permissions
7659 of a file included in the package has changed, dpkg
7660 arranges for the ownership and permissions to be
7661 correctly set upon installation. However, this does not
7662 extend to directories; the permissions and ownership of
7663 directories already on the system does not change on
7664 install or upgrade of packages. This makes sense, since
7665 otherwise common directories like <tt>/usr</tt> would
7666 always be in flux. To correctly change permissions of a
7667 directory the package owns, explicit action is required,
7668 usually in the <tt>postinst</tt> script. Care must be
7669 taken to handle downgrades as well, in that case.
7676 Setuid and setgid executables should be mode 4755 or 2755
7677 respectively, and owned by the appropriate user or group.
7678 They should not be made unreadable (modes like 4711 or
7679 2711 or even 4111); doing so achieves no extra security,
7680 because anyone can find the binary in the freely available
7681 Debian package; it is merely inconvenient. For the same
7682 reason you should not restrict read or execute permissions
7683 on non-set-id executables.
7687 Some setuid programs need to be restricted to particular
7688 sets of users, using file permissions. In this case they
7689 should be owned by the uid to which they are set-id, and by
7690 the group which should be allowed to execute them. They
7691 should have mode 4754; again there is no point in making
7692 them unreadable to those users who must not be allowed to
7697 It is possible to arrange that the system administrator can
7698 reconfigure the package to correspond to their local
7699 security policy by changing the permissions on a binary:
7700 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7701 described below.<footnote>
7702 Ordinary files installed by <prgn>dpkg</prgn> (as
7703 opposed to <tt>conffile</tt>s and other similar objects)
7704 normally have their permissions reset to the distributed
7705 permissions when the package is reinstalled. However,
7706 the use of <prgn>dpkg-statoverride</prgn> overrides this
7707 default behavior. If you use this method, you should
7708 remember to describe <prgn>dpkg-statoverride</prgn> in
7709 the package documentation; being a relatively new
7710 addition to Debian, it is probably not yet well-known.
7712 Another method you should consider is to create a group for
7713 people allowed to use the program(s) and make any setuid
7714 executables executable only by that group.
7718 If you need to create a new user or group for your package
7719 there are two possibilities. Firstly, you may need to
7720 make some files in the binary package be owned by this
7721 user or group, or you may need to compile the user or
7722 group id (rather than just the name) into the binary
7723 (though this latter should be avoided if possible, as in
7724 this case you need a statically allocated id).</p>
7727 If you need a statically allocated id, you must ask for a
7728 user or group id from the <tt>base-passwd</tt> maintainer,
7729 and must not release the package until you have been
7730 allocated one. Once you have been allocated one you must
7731 either make the package depend on a version of the
7732 <tt>base-passwd</tt> package with the id present in
7733 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7734 your package to create the user or group itself with the
7735 correct id (using <tt>adduser</tt>) in its
7736 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7737 the <prgn>postinst</prgn> is to be preferred if it is
7738 possible, otherwise a pre-dependency will be needed on the
7739 <tt>adduser</tt> package.)
7743 On the other hand, the program might be able to determine
7744 the uid or gid from the user or group name at runtime, so
7745 that a dynamically allocated id can be used. In this case
7746 you should choose an appropriate user or group name,
7747 discussing this on <prgn>debian-devel</prgn> and checking
7748 with the <package/base-passwd/ maintainer that it is unique and that
7749 they do not wish you to use a statically allocated id
7750 instead. When this has been checked you must arrange for
7751 your package to create the user or group if necessary using
7752 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7753 <prgn>postinst</prgn> script (again, the latter is to be
7754 preferred if it is possible).
7758 Note that changing the numeric value of an id associated
7759 with a name is very difficult, and involves searching the
7760 file system for all appropriate files. You need to think
7761 carefully whether a static or dynamic id is required, since
7762 changing your mind later will cause problems.
7765 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7767 This section is not intended as policy, but as a
7768 description of the use of <prgn>dpkg-statoverride</prgn>.
7772 If a system administrator wishes to have a file (or
7773 directory or other such thing) installed with owner and
7774 permissions different from those in the distributed Debian
7775 package, they can use the <prgn>dpkg-statoverride</prgn>
7776 program to instruct <prgn>dpkg</prgn> to use the different
7777 settings every time the file is installed. Thus the
7778 package maintainer should distribute the files with their
7779 normal permissions, and leave it for the system
7780 administrator to make any desired changes. For example, a
7781 daemon which is normally required to be setuid root, but
7782 in certain situations could be used without being setuid,
7783 should be installed setuid in the <tt>.deb</tt>. Then the
7784 local system administrator can change this if they wish.
7785 If there are two standard ways of doing it, the package
7786 maintainer can use <tt>debconf</tt> to find out the
7787 preference, and call <prgn>dpkg-statoverride</prgn> in the
7788 maintainer script if necessary to accommodate the system
7789 administrator's choice. Care must be taken during
7790 upgrades to not override an existing setting.
7794 Given the above, <prgn>dpkg-statoverride</prgn> is
7795 essentially a tool for system administrators and would not
7796 normally be needed in the maintainer scripts. There is
7797 one type of situation, though, where calls to
7798 <prgn>dpkg-statoverride</prgn> would be needed in the
7799 maintainer scripts, and that involves packages which use
7800 dynamically allocated user or group ids. In such a
7801 situation, something like the following idiom can be very
7802 helpful in the package's <prgn>postinst</prgn>, where
7803 <tt>sysuser</tt> is a dynamically allocated id:
7805 for i in /usr/bin/foo /usr/sbin/bar
7807 # only do something when no setting exists
7808 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7810 #include: debconf processing, question about foo and bar
7811 if [ "$RET" = "true" ] ; then
7812 dpkg-statoverride --update --add sysuser root 4755 $i
7817 The corresponding code to remove the override when the package
7820 for i in /usr/bin/foo /usr/sbin/bar
7822 if dpkg-statoverride --list $i >/dev/null 2>&1
7824 dpkg-statoverride --remove $i
7834 <chapt id="customized-programs">
7835 <heading>Customized programs</heading>
7837 <sect id="arch-spec">
7838 <heading>Architecture specification strings</heading>
7841 If a program needs to specify an <em>architecture specification
7842 string</em> in some place, it should select one of the
7843 strings provided by <tt>dpkg-architecture -L</tt>. The
7844 strings are in the format
7845 <tt><var>os</var>-<var>arch</var></tt>, though the OS part
7846 is sometimes elided, as when the OS is Linux.<footnote>
7847 <p>Currently, the strings are:
7848 i386 ia64 alpha amd64 armeb arm hppa m32r m68k mips
7849 mipsel powerpc ppc64 s390 s390x sh3 sh3eb sh4 sh4eb
7850 sparc darwin-i386 darwin-ia64 darwin-alpha darwin-amd64
7851 darwin-armeb darwin-arm darwin-hppa darwin-m32r
7852 darwin-m68k darwin-mips darwin-mipsel darwin-powerpc
7853 darwin-ppc64 darwin-s390 darwin-s390x darwin-sh3
7854 darwin-sh3eb darwin-sh4 darwin-sh4eb darwin-sparc
7855 freebsd-i386 freebsd-ia64 freebsd-alpha freebsd-amd64
7856 freebsd-armeb freebsd-arm freebsd-hppa freebsd-m32r
7857 freebsd-m68k freebsd-mips freebsd-mipsel freebsd-powerpc
7858 freebsd-ppc64 freebsd-s390 freebsd-s390x freebsd-sh3
7859 freebsd-sh3eb freebsd-sh4 freebsd-sh4eb freebsd-sparc
7860 kfreebsd-i386 kfreebsd-ia64 kfreebsd-alpha
7861 kfreebsd-amd64 kfreebsd-armeb kfreebsd-arm kfreebsd-hppa
7862 kfreebsd-m32r kfreebsd-m68k kfreebsd-mips
7863 kfreebsd-mipsel kfreebsd-powerpc kfreebsd-ppc64
7864 kfreebsd-s390 kfreebsd-s390x kfreebsd-sh3 kfreebsd-sh3eb
7865 kfreebsd-sh4 kfreebsd-sh4eb kfreebsd-sparc knetbsd-i386
7866 knetbsd-ia64 knetbsd-alpha knetbsd-amd64 knetbsd-armeb
7867 knetbsd-arm knetbsd-hppa knetbsd-m32r knetbsd-m68k
7868 knetbsd-mips knetbsd-mipsel knetbsd-powerpc
7869 knetbsd-ppc64 knetbsd-s390 knetbsd-s390x knetbsd-sh3
7870 knetbsd-sh3eb knetbsd-sh4 knetbsd-sh4eb knetbsd-sparc
7871 netbsd-i386 netbsd-ia64 netbsd-alpha netbsd-amd64
7872 netbsd-armeb netbsd-arm netbsd-hppa netbsd-m32r
7873 netbsd-m68k netbsd-mips netbsd-mipsel netbsd-powerpc
7874 netbsd-ppc64 netbsd-s390 netbsd-s390x netbsd-sh3
7875 netbsd-sh3eb netbsd-sh4 netbsd-sh4eb netbsd-sparc
7876 openbsd-i386 openbsd-ia64 openbsd-alpha openbsd-amd64
7877 openbsd-armeb openbsd-arm openbsd-hppa openbsd-m32r
7878 openbsd-m68k openbsd-mips openbsd-mipsel openbsd-powerpc
7879 openbsd-ppc64 openbsd-s390 openbsd-s390x openbsd-sh3
7880 openbsd-sh3eb openbsd-sh4 openbsd-sh4eb openbsd-sparc
7881 hurd-i386 hurd-ia64 hurd-alpha hurd-amd64 hurd-armeb
7882 hurd-arm hurd-hppa hurd-m32r hurd-m68k hurd-mips
7883 hurd-mipsel hurd-powerpc hurd-ppc64 hurd-s390 hurd-s390x
7884 hurd-sh3 hurd-sh3eb hurd-sh4 hurd-sh4eb hurd-sparc
7890 Note that we don't want to use
7891 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
7892 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
7893 since this would make our programs incompatible with other
7894 Linux distributions. We also don't use something like
7895 <tt><var>arch</var>-unknown-linux</tt>, since the
7896 <tt>unknown</tt> does not look very good.
7901 <heading>Daemons</heading>
7904 The configuration files <file>/etc/services</file>,
7905 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
7906 by the <prgn>netbase</prgn> package and must not be modified
7911 If a package requires a new entry in one of these files, the
7912 maintainer should get in contact with the
7913 <prgn>netbase</prgn> maintainer, who will add the entries
7914 and release a new version of the <prgn>netbase</prgn>
7919 The configuration file <file>/etc/inetd.conf</file> must not be
7920 modified by the package's scripts except via the
7921 <prgn>update-inetd</prgn> script or the
7922 <file>DebianNet.pm</file> Perl module. See their documentation
7923 for details on how to add entries.
7927 If a package wants to install an example entry into
7928 <file>/etc/inetd.conf</file>, the entry must be preceded with
7929 exactly one hash character (<tt>#</tt>). Such lines are
7930 treated as "commented out by user" by the
7931 <prgn>update-inetd</prgn> script and are not changed or
7932 activated during package updates.
7937 <heading>Using pseudo-ttys and modifying wtmp, utmp and
7941 Some programs need to create pseudo-ttys. This should be done
7942 using Unix98 ptys if the C library supports it. The resulting
7943 program must not be installed setuid root, unless that
7944 is required for other functionality.
7948 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
7949 <file>/var/log/lastlog</file> must be installed writable by
7950 group <tt>utmp</tt>. Programs which need to modify those
7951 files must be installed setgid <tt>utmp</tt>.
7956 <heading>Editors and pagers</heading>
7959 Some programs have the ability to launch an editor or pager
7960 program to edit or display a text document. Since there are
7961 lots of different editors and pagers available in the Debian
7962 distribution, the system administrator and each user should
7963 have the possibility to choose their preferred editor and
7968 In addition, every program should choose a good default
7969 editor/pager if none is selected by the user or system
7974 Thus, every program that launches an editor or pager must
7975 use the EDITOR or PAGER environment variable to determine
7976 the editor or pager the user wishes to use. If these
7977 variables are not set, the programs <file>/usr/bin/editor</file>
7978 and <file>/usr/bin/pager</file> should be used, respectively.
7982 These two files are managed through the <prgn>dpkg</prgn>
7983 "alternatives" mechanism. Thus every package providing an
7984 editor or pager must call the
7985 <prgn>update-alternatives</prgn> script to register these
7990 If it is very hard to adapt a program to make use of the
7991 EDITOR or PAGER variables, that program may be configured to
7992 use <file>/usr/bin/sensible-editor</file> and
7993 <file>/usr/bin/sensible-pager</file> as the editor or pager
7994 program respectively. These are two scripts provided in the
7995 <package>sensible-utils</package> package that check the EDITOR
7996 and PAGER variables and launch the appropriate program, and fall
7997 back to <file>/usr/bin/editor</file>
7998 and <file>/usr/bin/pager</file> if the variable is not set.
8002 A program may also use the VISUAL environment variable to
8003 determine the user's choice of editor. If it exists, it
8004 should take precedence over EDITOR. This is in fact what
8005 <file>/usr/bin/sensible-editor</file> does.
8009 It is not required for a package to depend on
8010 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8011 package to provide such virtual packages.<footnote>
8012 The Debian base system already provides an editor and a
8018 <sect id="web-appl">
8019 <heading>Web servers and applications</heading>
8022 This section describes the locations and URLs that should
8023 be used by all web servers and web applications in the
8030 Cgi-bin executable files are installed in the
8032 <example compact="compact">
8033 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8035 and should be referred to as
8036 <example compact="compact">
8037 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8043 <p>Access to HTML documents</p>
8046 HTML documents for a package are stored in
8047 <file>/usr/share/doc/<var>package</var></file>
8048 and can be referred to as
8049 <example compact="compact">
8050 http://localhost/doc/<var>package</var>/<var>filename</var>
8055 The web server should restrict access to the document
8056 tree so that only clients on the same host can read
8057 the documents. If the web server does not support such
8058 access controls, then it should not provide access at
8059 all, or ask about providing access during installation.
8064 <p>Access to images</p>
8066 It is recommended that images for a package be stored
8067 in <tt>/usr/share/images/<var>package</var></tt> and
8068 may be referred to through an alias <tt>/images/</tt>
8071 http://localhost/images/<package>/<filename>
8078 <p>Web Document Root</p>
8081 Web Applications should try to avoid storing files in
8082 the Web Document Root. Instead they should use the
8083 /usr/share/doc/<var>package</var> directory for
8084 documents and register the Web Application via the
8085 <package>doc-base</package> package. If access to the
8086 web document root is unavoidable then use
8087 <example compact="compact">
8090 as the Document Root. This might be just a symbolic
8091 link to the location where the system administrator
8092 has put the real document root.
8095 <item><p>Providing httpd and/or httpd-cgi</p>
8097 All web servers should provide the virtual package
8098 <tt>httpd</tt>. If a web server has CGI support it should
8099 provide <tt>httpd-cgi</tt> additionally.
8102 All web applications which do not contain CGI scripts should
8103 depend on <tt>httpd</tt>, all those web applications which
8104 <tt>do</tt> contain CGI scripts, should depend on
8112 <sect id="mail-transport-agents">
8113 <heading>Mail transport, delivery and user agents</heading>
8116 Debian packages which process electronic mail, whether mail
8117 user agents (MUAs) or mail transport agents (MTAs), must
8118 ensure that they are compatible with the configuration
8119 decisions below. Failure to do this may result in lost
8120 mail, broken <tt>From:</tt> lines, and other serious brain
8125 The mail spool is <file>/var/mail</file> and the interface to
8126 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8127 the FHS). On older systems, the mail spool may be
8128 physically located in <file>/var/spool/mail</file>, but all
8129 access to the mail spool should be via the
8130 <file>/var/mail</file> symlink. The mail spool is part of the
8131 base system and not part of the MTA package.
8135 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8136 programs (such as IMAP daemons) must lock the mailbox in an
8137 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8138 be combined with dot locking. To avoid deadlocks, a program
8139 should use <tt>fcntl()</tt> first and dot locking after
8140 this, or alternatively implement the two locking methods in
8141 a non blocking way<footnote>
8142 If it is not possible to establish both locks, the
8143 system shouldn't wait for the second lock to be
8144 established, but remove the first lock, wait a (random)
8145 time, and start over locking again.
8146 </footnote>. Using the functions <tt>maillock</tt> and
8147 <tt>mailunlock</tt> provided by the
8148 <tt>liblockfile*</tt><footnote>
8149 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8150 to use these functions.
8151 </footnote> packages is the recommended way to realize this.
8155 Mailboxes are generally either mode 600 and owned by
8156 <var>user</var> or mode 660 and owned by
8157 <tt><var>user</var>:mail</tt><footnote>
8158 There are two traditional permission schemes for mail spools:
8159 mode 600 with all mail delivery done by processes running as
8160 the destination user, or mode 660 and owned by group mail with
8161 mail delivery done by a process running as a system user in
8162 group mail. Historically, Debian required mode 660 mail
8163 spools to enable the latter model, but that model has become
8164 increasingly uncommon and the principle of least privilege
8165 indicates that mail systems that use the first model should
8166 use permissions of 600. If delivery to programs is permitted,
8167 it's easier to keep the mail system secure if the delivery
8168 agent runs as the destination user. Debian Policy therefore
8169 permits either scheme.
8170 </footnote>. The local system administrator may choose a
8171 different permission scheme; packages should not make
8172 assumptions about the permission and ownership of mailboxes
8173 unless required (such as when creating a new mailbox). A MUA
8174 may remove a mailbox (unless it has nonstandard permissions) in
8175 which case the MTA or another MUA must recreate it if needed.
8179 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8180 be setgid mail to do the locking mentioned above (and
8181 must obviously avoid accessing other users' mailboxes
8182 using this privilege).</p>
8185 <file>/etc/aliases</file> is the source file for the system mail
8186 aliases (e.g., postmaster, usenet, etc.), it is the one
8187 which the sysadmin and <prgn>postinst</prgn> scripts may
8188 edit. After <file>/etc/aliases</file> is edited the program or
8189 human editing it must call <prgn>newaliases</prgn>. All MTA
8190 packages must come with a <prgn>newaliases</prgn> program,
8191 even if it does nothing, but older MTA packages did not do
8192 this so programs should not fail if <prgn>newaliases</prgn>
8193 cannot be found. Note that because of this, all MTA
8194 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8195 <tt>Replaces: mail-transport-agent</tt> control file
8200 The convention of writing <tt>forward to
8201 <var>address</var></tt> in the mailbox itself is not
8202 supported. Use a <tt>.forward</tt> file instead.</p>
8205 The <prgn>rmail</prgn> program used by UUCP
8206 for incoming mail should be <file>/usr/sbin/rmail</file>.
8207 Likewise, <prgn>rsmtp</prgn>, for receiving
8208 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8212 If your package needs to know what hostname to use on (for
8213 example) outgoing news and mail messages which are generated
8214 locally, you should use the file <file>/etc/mailname</file>. It
8215 will contain the portion after the username and <tt>@</tt>
8216 (at) sign for email addresses of users on the machine
8217 (followed by a newline).
8221 Such a package should check for the existence of this file
8222 when it is being configured. If it exists, it should be
8223 used without comment, although an MTA's configuration script
8224 may wish to prompt the user even if it finds that this file
8225 exists. If the file does not exist, the package should
8226 prompt the user for the value (preferably using
8227 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8228 as well as using it in the package's configuration. The
8229 prompt should make it clear that the name will not just be
8230 used by that package. For example, in this situation the
8231 <tt>inn</tt> package could say something like:
8232 <example compact="compact">
8233 Please enter the "mail name" of your system. This is the
8234 hostname portion of the address to be shown on outgoing
8235 news and mail messages. The default is
8236 <var>syshostname</var>, your system's host name. Mail
8237 name ["<var>syshostname</var>"]:
8239 where <var>syshostname</var> is the output of <tt>hostname
8245 <heading>News system configuration</heading>
8248 All the configuration files related to the NNTP (news)
8249 servers and clients should be located under
8250 <file>/etc/news</file>.</p>
8253 There are some configuration issues that apply to a number
8254 of news clients and server packages on the machine. These
8258 <tag><file>/etc/news/organization</file></tag>
8260 A string which should appear as the
8261 organization header for all messages posted
8262 by NNTP clients on the machine
8265 <tag><file>/etc/news/server</file></tag>
8267 Contains the FQDN of the upstream NNTP
8268 server, or localhost if the local machine is
8273 Other global files may be added as required for cross-package news
8280 <heading>Programs for the X Window System</heading>
8283 <heading>Providing X support and package priorities</heading>
8286 Programs that can be configured with support for the X
8287 Window System must be configured to do so and must declare
8288 any package dependencies necessary to satisfy their
8289 runtime requirements when using the X Window System. If
8290 such a package is of higher priority than the X packages
8291 on which it depends, it is required that either the
8292 X-specific components be split into a separate package, or
8293 that an alternative version of the package, which includes
8294 X support, be provided, or that the package's priority be
8300 <heading>Packages providing an X server</heading>
8303 Packages that provide an X server that, directly or
8304 indirectly, communicates with real input and display
8305 hardware should declare in their control data that they
8306 provide the virtual package <tt>xserver</tt>.<footnote>
8307 This implements current practice, and provides an
8308 actual policy for usage of the <tt>xserver</tt>
8309 virtual package which appears in the virtual packages
8310 list. In a nutshell, X servers that interface
8311 directly with the display and input hardware or via
8312 another subsystem (e.g., GGI) should provide
8313 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8314 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8320 <heading>Packages providing a terminal emulator</heading>
8323 Packages that provide a terminal emulator for the X Window
8324 System which meet the criteria listed below should declare
8325 in their control data that they provide the virtual
8326 package <tt>x-terminal-emulator</tt>. They should also
8327 register themselves as an alternative for
8328 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8333 To be an <tt>x-terminal-emulator</tt>, a program must:
8334 <list compact="compact">
8336 Be able to emulate a DEC VT100 terminal, or a
8337 compatible terminal.
8341 Support the command-line option <tt>-e
8342 <var>command</var></tt>, which creates a new
8343 terminal window<footnote>
8344 "New terminal window" does not necessarily mean
8345 a new top-level X window directly parented by
8346 the window manager; it could, if the terminal
8347 emulator application were so coded, be a new
8348 "view" in a multiple-document interface (MDI).
8350 and runs the specified <var>command</var>,
8351 interpreting the entirety of the rest of the command
8352 line as a command to pass straight to exec, in the
8353 manner that <tt>xterm</tt> does.
8357 Support the command-line option <tt>-T
8358 <var>title</var></tt>, which creates a new terminal
8359 window with the window title <var>title</var>.
8366 <heading>Packages providing a window manager</heading>
8369 Packages that provide a window manager should declare in
8370 their control data that they provide the virtual package
8371 <tt>x-window-manager</tt>. They should also register
8372 themselves as an alternative for
8373 <file>/usr/bin/x-window-manager</file>, with a priority
8374 calculated as follows:
8375 <list compact="compact">
8377 Start with a priority of 20.
8381 If the window manager supports the Debian menu
8382 system, add 20 points if this support is available
8383 in the package's default configuration (i.e., no
8384 configuration files belonging to the system or user
8385 have to be edited to activate the feature); if
8386 configuration files must be modified, add only 10
8392 If the window manager complies with <url
8393 id="http://www.freedesktop.org/Standards/wm-spec"
8394 name="The Window Manager Specification Project">,
8395 written by the <url id="http://www.freedesktop.org/"
8396 name="Free Desktop Group">, add 40 points.
8400 If the window manager permits the X session to be
8401 restarted using a <em>different</em> window manager
8402 (without killing the X server) in its default
8403 configuration, add 10 points; otherwise add none.
8410 <heading>Packages providing fonts</heading>
8413 Packages that provide fonts for the X Window
8415 For the purposes of Debian Policy, a "font for the X
8416 Window System" is one which is accessed via X protocol
8417 requests. Fonts for the Linux console, for PostScript
8418 renderer, or any other purpose, do not fit this
8419 definition. Any tool which makes such fonts available
8420 to the X Window System, however, must abide by this
8423 must do a number of things to ensure that they are both
8424 available without modification of the X or font server
8425 configuration, and that they do not corrupt files used by
8426 other font packages to register information about
8430 Fonts of any type supported by the X Window System
8431 must be in a separate binary package from any
8432 executables, libraries, or documentation (except
8433 that specific to the fonts shipped, such as their
8434 license information). If one or more of the fonts
8435 so packaged are necessary for proper operation of
8436 the package with which they are associated the font
8437 package may be Recommended; if the fonts merely
8438 provide an enhancement, a Suggests relationship may
8439 be used. Packages must not Depend on font
8441 This is because the X server may retrieve fonts
8442 from the local file system or over the network
8443 from an X font server; the Debian package system
8444 is empowered to deal only with the local
8450 BDF fonts must be converted to PCF fonts with the
8451 <prgn>bdftopcf</prgn> utility (available in the
8452 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8453 placed in a directory that corresponds to their
8455 <list compact="compact">
8457 100 dpi fonts must be placed in
8458 <file>/usr/share/fonts/X11/100dpi/</file>.
8462 75 dpi fonts must be placed in
8463 <file>/usr/share/fonts/X11/75dpi/</file>.
8467 Character-cell fonts, cursor fonts, and other
8468 low-resolution fonts must be placed in
8469 <file>/usr/share/fonts/X11/misc/</file>.
8475 Type 1 fonts must be placed in
8476 <file>/usr/share/fonts/X11/Type1/</file>. If font
8477 metric files are available, they must be placed here
8482 Subdirectories of <file>/usr/share/fonts/X11/</file>
8483 other than those listed above must be neither
8484 created nor used. (The <file>PEX</file>, <file>CID</file>,
8485 <file>Speedo</file>, and <file>cyrillic</file> directories
8486 are excepted for historical reasons, but installation of
8487 files into these directories remains discouraged.)
8491 Font packages may, instead of placing files directly
8492 in the X font directories listed above, provide
8493 symbolic links in that font directory pointing to
8494 the files' actual location in the filesystem. Such
8495 a location must comply with the FHS.
8499 Font packages should not contain both 75dpi and
8500 100dpi versions of a font. If both are available,
8501 they should be provided in separate binary packages
8502 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8503 the names of the packages containing the
8504 corresponding fonts.
8508 Fonts destined for the <file>misc</file> subdirectory
8509 should not be included in the same package as 75dpi
8510 or 100dpi fonts; instead, they should be provided in
8511 a separate package with <tt>-misc</tt> appended to
8516 Font packages must not provide the files
8517 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8518 <file>fonts.scale</file> in a font directory:
8521 <file>fonts.dir</file> files must not be provided at all.
8525 <file>fonts.alias</file> and <file>fonts.scale</file>
8526 files, if needed, should be provided in the
8528 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8529 where <var>fontdir</var> is the name of the
8531 <file>/usr/share/fonts/X11/</file> where the
8532 package's corresponding fonts are stored
8533 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8534 <var>package</var> is the name of the package
8535 that provides these fonts, and
8536 <var>extension</var> is either <tt>scale</tt>
8537 or <tt>alias</tt>, whichever corresponds to
8544 Font packages must declare a dependency on
8545 <tt>xfonts-utils</tt> in their control
8550 Font packages that provide one or more
8551 <file>fonts.scale</file> files as described above must
8552 invoke <prgn>update-fonts-scale</prgn> on each
8553 directory into which they installed fonts
8554 <em>before</em> invoking
8555 <prgn>update-fonts-dir</prgn> on that directory.
8556 This invocation must occur in both the
8557 <prgn>postinst</prgn> (for all arguments) and
8558 <prgn>postrm</prgn> (for all arguments except
8559 <tt>upgrade</tt>) scripts.
8563 Font packages that provide one or more
8564 <file>fonts.alias</file> files as described above must
8565 invoke <prgn>update-fonts-alias</prgn> on each
8566 directory into which they installed fonts. This
8567 invocation must occur in both the
8568 <prgn>postinst</prgn> (for all arguments) and
8569 <prgn>postrm</prgn> (for all arguments except
8570 <tt>upgrade</tt>) scripts.
8574 Font packages must invoke
8575 <prgn>update-fonts-dir</prgn> on each directory into
8576 which they installed fonts. This invocation must
8577 occur in both the <prgn>postinst</prgn> (for all
8578 arguments) and <prgn>postrm</prgn> (for all
8579 arguments except <tt>upgrade</tt>) scripts.
8583 Font packages must not provide alias names for the
8584 fonts they include which collide with alias names
8585 already in use by fonts already packaged.
8589 Font packages must not provide fonts with the same
8590 XLFD registry name as another font already packaged.
8596 <sect1 id="appdefaults">
8597 <heading>Application defaults files</heading>
8600 Application defaults files must be installed in the
8601 directory <file>/etc/X11/app-defaults/</file> (use of a
8602 localized subdirectory of <file>/etc/X11/</file> as described
8603 in the <em>X Toolkit Intrinsics - C Language
8604 Interface</em> manual is also permitted). They must be
8605 registered as <tt>conffile</tt>s or handled as
8606 configuration files.
8610 Customization of programs' X resources may also be
8611 supported with the provision of a file with the same name
8612 as that of the package placed in
8613 the <file>/etc/X11/Xresources/</file> directory, which
8614 must be registered as a <tt>conffile</tt> or handled as a
8615 configuration file.<footnote>
8616 Note that this mechanism is not the same as using
8617 app-defaults; app-defaults are tied to the client
8618 binary on the local file system, whereas X resources
8619 are stored in the X server and affect all connecting
8626 <heading>Installation directory issues</heading>
8629 Historically, packages using the X Window System used a
8630 separate set of installation directories from other packages.
8631 This practice has been discontinued and packages using the X
8632 Window System should now generally be installed in the same
8633 directories as any other package. Specifically, packages must
8634 not install files under the <file>/usr/X11R6/</file> directory
8635 and the <file>/usr/X11R6/</file> directory hierarchy should be
8636 regarded as obsolete.
8640 Include files previously installed under
8641 <file>/usr/X11R6/include/X11/</file> should be installed into
8642 <file>/usr/include/X11/</file>. For files previously
8643 installed into subdirectories of
8644 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8645 determine if subdirectories of <file>/usr/lib/</file> and
8646 <file>/usr/share/</file> can be used. If not, a subdirectory
8647 of <file>/usr/lib/X11/</file> should be used.
8651 Configuration files for window, display, or session managers
8652 or other applications that are tightly integrated with the X
8653 Window System may be placed in a subdirectory
8654 of <file>/etc/X11/</file> corresponding to the package name.
8655 Other X Window System applications should use
8656 the <file>/etc/</file> directory unless otherwise mandated by
8657 policy (such as for <ref id="appdefaults">).
8662 <heading>The OSF/Motif and OpenMotif libraries</heading>
8665 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8666 OpenMotif libraries</em><footnote>
8667 OSF/Motif and OpenMotif are collectively referred to as
8668 "Motif" in this policy document.
8670 should be compiled against and tested with LessTif (a free
8671 re-implementation of Motif) instead. If the maintainer
8672 judges that the program or programs do not work
8673 sufficiently well with LessTif to be distributed and
8674 supported, but do so when compiled against Motif, then two
8675 versions of the package should be created; one linked
8676 statically against Motif and with <tt>-smotif</tt>
8677 appended to the package name, and one linked dynamically
8678 against Motif and with <tt>-dmotif</tt> appended to the
8683 Both Motif-linked versions are dependent
8684 upon non-DFSG-compliant software and thus cannot be
8685 uploaded to the <em>main</em> distribution; if the
8686 software is itself DFSG-compliant it may be uploaded to
8687 the <em>contrib</em> distribution. While known existing
8688 versions of Motif permit unlimited redistribution of
8689 binaries linked against the library (whether statically or
8690 dynamically), it is the package maintainer's
8691 responsibility to determine whether this is permitted by
8692 the license of the copy of Motif in their possession.
8698 <heading>Perl programs and modules</heading>
8701 Perl programs and modules should follow the current Perl policy.
8705 The Perl policy can be found in the <tt>perl-policy</tt>
8706 files in the <tt>debian-policy</tt> package.
8707 It is also available from the Debian web mirrors at
8708 <tt><url name="/doc/packaging-manuals/perl-policy/"
8709 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8714 <heading>Emacs lisp programs</heading>
8717 Please refer to the "Debian Emacs Policy" for details of how to
8718 package emacs lisp programs.
8722 The Emacs policy is available in
8723 <file>debian-emacs-policy.gz</file> of the
8724 <package>emacsen-common</package> package.
8725 It is also available from the Debian web mirrors at
8726 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8727 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8732 <heading>Games</heading>
8735 The permissions on <file>/var/games</file> are mode 755, owner
8736 <tt>root</tt> and group <tt>root</tt>.
8740 Each game decides on its own security policy.</p>
8743 Games which require protected, privileged access to
8744 high-score files, saved games, etc., may be made
8745 set-<em>group</em>-id (mode 2755) and owned by
8746 <tt>root:games</tt>, and use files and directories with
8747 appropriate permissions (770 <tt>root:games</tt>, for
8748 example). They must not be made
8749 set-<em>user</em>-id, as this causes security problems. (If
8750 an attacker can subvert any set-user-id game they can
8751 overwrite the executable of any other, causing other players
8752 of these games to run a Trojan horse program. With a
8753 set-group-id game the attacker only gets access to less
8754 important game data, and if they can get at the other
8755 players' accounts at all it will take considerably more
8759 Some packages, for example some fortune cookie programs, are
8760 configured by the upstream authors to install with their
8761 data files or other static information made unreadable so
8762 that they can only be accessed through set-id programs
8763 provided. You should not do this in a Debian package: anyone can
8764 download the <file>.deb</file> file and read the data from it,
8765 so there is no point making the files unreadable. Not
8766 making the files unreadable also means that you don't have
8767 to make so many programs set-id, which reduces the risk of a
8771 As described in the FHS, binaries of games should be
8772 installed in the directory <file>/usr/games</file>. This also
8773 applies to games that use the X Window System. Manual pages
8774 for games (X and non-X games) should be installed in
8775 <file>/usr/share/man/man6</file>.</p>
8781 <heading>Documentation</heading>
8784 <heading>Manual pages</heading>
8787 You should install manual pages in <prgn>nroff</prgn> source
8788 form, in appropriate places under <file>/usr/share/man</file>.
8789 You should only use sections 1 to 9 (see the FHS for more
8790 details). You must not install a pre-formatted "cat page".
8794 Each program, utility, and function should have an
8795 associated manual page included in the same package. It is
8796 suggested that all configuration files also have a manual
8797 page included as well. Manual pages for protocols and other
8798 auxiliary things are optional.
8802 If no manual page is available, this is considered as a bug
8803 and should be reported to the Debian Bug Tracking System (the
8804 maintainer of the package is allowed to write this bug report
8805 themselves, if they so desire). Do not close the bug report
8806 until a proper man page is available.<footnote>
8807 It is not very hard to write a man page. See the
8808 <url id="http://www.schweikhardt.net/man_page_howto.html"
8809 name="Man-Page-HOWTO">,
8810 <manref name="man" section="7">, the examples
8811 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8812 the helper programs <prgn>help2man</prgn>, or the
8813 directory <file>/usr/share/doc/man-db/examples</file>.
8818 You may forward a complaint about a missing man page to the
8819 upstream authors, and mark the bug as forwarded in the
8820 Debian bug tracking system. Even though the GNU Project do
8821 not in general consider the lack of a man page to be a bug,
8822 we do; if they tell you that they don't consider it a bug
8823 you should leave the bug in our bug tracking system open
8828 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8832 If one man page needs to be accessible via several names it
8833 is better to use a symbolic link than the <file>.so</file>
8834 feature, but there is no need to fiddle with the relevant
8835 parts of the upstream source to change from <file>.so</file> to
8836 symlinks: don't do it unless it's easy. You should not
8837 create hard links in the manual page directories, nor put
8838 absolute filenames in <file>.so</file> directives. The filename
8839 in a <file>.so</file> in a man page should be relative to the
8840 base of the man page tree (usually
8841 <file>/usr/share/man</file>). If you do not create any links
8842 (whether symlinks, hard links, or <tt>.so</tt> directives)
8843 in the file system to the alternate names of the man page,
8844 then you should not rely on <prgn>man</prgn> finding your
8845 man page under those names based solely on the information in
8846 the man page's header.<footnote>
8847 Supporting this in <prgn>man</prgn> often requires
8848 unreasonable processing time to find a manual page or to
8849 report that none exists, and moves knowledge into man's
8850 database that would be better left in the file system.
8851 This support is therefore deprecated and will cease to
8852 be present in the future.
8857 Manual pages in locale-specific subdirectories of
8858 <file>/usr/share/man</file> should use either UTF-8 or the usual
8859 legacy encoding for that language (normally the one corresponding
8860 to the shortest relevant locale name in
8861 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8862 <file>/usr/share/man/fr</file> should use either UTF-8 or
8863 ISO-8859-1.<footnote>
8864 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8865 use. In future, all manual pages will be required to use
8871 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
8872 included in the subdirectory name unless it indicates a
8873 significant difference in the language, as this excludes
8874 speakers of the language in other countries.<footnote>
8875 At the time of writing, Chinese and Portuguese are the main
8876 languages with such differences, so <file>pt_BR</file>,
8877 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
8882 If a localized version of a manual page is provided, it should
8883 either be up-to-date or it should be obvious to the reader that
8884 it is outdated and the original manual page should be used
8885 instead. This can be done either by a note at the beginning of
8886 the manual page or by showing the missing or changed portions in
8887 the original language instead of the target language.
8892 <heading>Info documents</heading>
8895 Info documents should be installed in <file>/usr/share/info</file>.
8896 They should be compressed with <tt>gzip -9</tt>.
8900 The <prgn>install-info</prgn> program maintains a directory of
8901 installed info documents in <file>/usr/share/info/dir</file> for
8902 the use of info readers.<footnote>
8903 It was previously necessary for packages installing info
8904 documents to run <prgn>install-info</prgn> from maintainer
8905 scripts. This is no longer necessary. The installation
8906 system now uses dpkg triggers.
8908 This file must not be included in packages. Packages containing
8909 info documents should depend on <tt>dpkg (>= 1.15.4) |
8910 install-info</tt> to ensure that the directory file is properly
8911 rebuilt during partial upgrades from Debian 5.0 (lenny) and
8916 Info documents should contain section and directory entry
8917 information in the document for the use
8918 of <prgn>install-info</prgn>. The section should be specified
8919 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
8920 space and the section of this info page. The directory entry or
8921 entries should be included between
8922 a <tt>START-INFO-DIR-ENTRY</tt> line and
8923 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
8925 INFO-DIR-SECTION Individual utilities
8926 START-INFO-DIR-ENTRY
8927 * example: (example). An example info directory entry.
8930 To determine which section to use, you should look
8931 at <file>/usr/share/info/dir</file> on your system and choose
8932 the most relevant (or create a new section if none of the
8933 current sections are relevant).<footnote>
8934 Normally, info documents are generated from Texinfo source.
8935 To include this information in the generated info document, if
8936 it is absent, add commands like:
8938 @dircategory Individual utilities
8940 * example: (example). An example info directory entry.
8943 to the Texinfo source of the document and ensure that the info
8944 documents are rebuilt from source during the package build.
8950 <heading>Additional documentation</heading>
8953 Any additional documentation that comes with the package may
8954 be installed at the discretion of the package maintainer.
8955 Plain text documentation should be installed in the directory
8956 <file>/usr/share/doc/<var>package</var></file>, where
8957 <var>package</var> is the name of the package, and
8958 compressed with <tt>gzip -9</tt> unless it is small.
8962 If a package comes with large amounts of documentation which
8963 many users of the package will not require you should create
8964 a separate binary package to contain it, so that it does not
8965 take up disk space on the machines of users who do not need
8966 or want it installed.</p>
8969 It is often a good idea to put text information files
8970 (<file>README</file>s, changelogs, and so forth) that come with
8971 the source package in <file>/usr/share/doc/<var>package</var></file>
8972 in the binary package. However, you don't need to install
8973 the instructions for building and installing the package, of
8977 Packages must not require the existence of any files in
8978 <file>/usr/share/doc/</file> in order to function
8980 The system administrator should be able to
8981 delete files in <file>/usr/share/doc/</file> without causing
8982 any programs to break.
8984 Any files that are referenced by programs but are also
8985 useful as stand alone documentation should be installed under
8986 <file>/usr/share/<var>package</var>/</file> with symbolic links from
8987 <file>/usr/share/doc/<var>package</var></file>.
8991 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
8992 link to another directory in <file>/usr/share/doc</file> only if
8993 the two packages both come from the same source and the
8994 first package Depends on the second.<footnote>
8996 Please note that this does not override the section on
8997 changelog files below, so the file
8998 <file>/usr/share/<var>package</var>/changelog.Debian.gz</file>
8999 must refer to the changelog for the current version of
9000 <var>package</var> in question. In practice, this means
9001 that the sources of the target and the destination of the
9002 symlink must be the same (same source package and
9009 Former Debian releases placed all additional documentation
9010 in <file>/usr/doc/<var>package</var></file>. This has been
9011 changed to <file>/usr/share/doc/<var>package</var></file>,
9012 and packages must not put documentation in the directory
9013 <file>/usr/doc/<var>package</var></file>. <footnote>
9014 At this phase of the transition, we no longer require a
9015 symbolic link in <file>/usr/doc/</file>. At a later point,
9016 policy shall change to make the symbolic links a bug.
9022 <heading>Preferred documentation formats</heading>
9025 The unification of Debian documentation is being carried out
9029 If your package comes with extensive documentation in a
9030 markup format that can be converted to various other formats
9031 you should if possible ship HTML versions in a binary
9032 package, in the directory
9033 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9034 its subdirectories.<footnote>
9035 The rationale: The important thing here is that HTML
9036 docs should be available in <em>some</em> package, not
9037 necessarily in the main binary package.
9042 Other formats such as PostScript may be provided at the
9043 package maintainer's discretion.
9047 <sect id="copyrightfile">
9048 <heading>Copyright information</heading>
9051 Every package must be accompanied by a verbatim copy of its
9052 copyright and distribution license in the file
9053 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9054 file must neither be compressed nor be a symbolic link.
9058 In addition, the copyright file must say where the upstream
9059 sources (if any) were obtained. It should name the original
9060 authors of the package and the Debian maintainer(s) who were
9061 involved with its creation.
9065 Packages in the <em>contrib</em> or <em>non-free</em> archive
9066 areas should state in the copyright file that the package is not
9067 part of the Debian GNU/Linux distribution and briefly explain
9072 A copy of the file which will be installed in
9073 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9074 be in <file>debian/copyright</file> in the source package.
9078 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9079 link to another directory in <file>/usr/share/doc</file> only if
9080 the two packages both come from the same source and the
9081 first package Depends on the second. These rules are
9082 important because copyrights must be extractable by
9087 Packages distributed under the UCB BSD license, the Apache
9088 license (version 2.0), the Artistic license, the GNU GPL
9089 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9090 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9091 files under <file>/usr/share/common-licenses</file>,<footnote>
9094 <file>/usr/share/common-licenses/BSD</file>,
9095 <file>/usr/share/common-licenses/Apache-2.0</file>,
9096 <file>/usr/share/common-licenses/Artistic</file>,
9097 <file>/usr/share/common-licenses/GPL-2</file>,
9098 <file>/usr/share/common-licenses/GPL-3</file>,
9099 <file>/usr/share/common-licenses/LGPL-2</file>,
9100 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9101 <file>/usr/share/common-licenses/LGPL-3</file>,
9102 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9103 <file>/usr/share/common-licenses/GFDL-1.3</file>
9106 </footnote> rather than quoting them in the copyright
9111 You should not use the copyright file as a general <file>README</file>
9112 file. If your package has such a file it should be
9113 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9114 <file>README.Debian</file> or some other appropriate place.</p>
9118 <heading>Examples</heading>
9121 Any examples (configurations, source files, whatever),
9122 should be installed in a directory
9123 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9124 files should not be referenced by any program: they're there
9125 for the benefit of the system administrator and users as
9126 documentation only. Architecture-specific example files
9127 should be installed in a directory
9128 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9130 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9131 latter directory itself may be a symbolic link to the
9136 If the purpose of a package is to provide examples, then the
9137 example files may be installed into
9138 <file>/usr/share/doc/<var>package</var></file>.
9142 <sect id="changelogs">
9143 <heading>Changelog files</heading>
9146 Packages that are not Debian-native must contain a
9147 compressed copy of the <file>debian/changelog</file> file from
9148 the Debian source tree in
9149 <file>/usr/share/doc/<var>package</var></file> with the name
9150 <file>changelog.Debian.gz</file>.
9154 If an upstream changelog is available, it should be accessible as
9155 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9156 plain text. If the upstream changelog is distributed in
9157 HTML, it should be made available in that form as
9158 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9159 and a plain text <file>changelog.gz</file> should be generated
9160 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9161 the upstream changelog files do not already conform to this
9162 naming convention, then this may be achieved either by
9163 renaming the files, or by adding a symbolic link, at the
9164 maintainer's discretion.<footnote>
9165 Rationale: People should not have to look in places for
9166 upstream changelogs merely because they are given
9167 different names or are distributed in HTML format.
9172 All of these files should be installed compressed using
9173 <tt>gzip -9</tt>, as they will become large with time even
9174 if they start out small.
9178 If the package has only one changelog which is used both as
9179 the Debian changelog and the upstream one because there is
9180 no separate upstream maintainer then that changelog should
9181 usually be installed as
9182 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9183 there is a separate upstream maintainer, but no upstream
9184 changelog, then the Debian changelog should still be called
9185 <file>changelog.Debian.gz</file>.
9189 For details about the format and contents of the Debian
9190 changelog file, please see <ref id="dpkgchangelog">.
9195 <appendix id="pkg-scope">
9196 <heading>Introduction and scope of these appendices</heading>
9199 These appendices are taken essentially verbatim from the
9200 now-deprecated Packaging Manual, version 3.2.1.0. They are
9201 the chapters which are likely to be of use to package
9202 maintainers and which have not already been included in the
9203 policy document itself. Most of these sections are very likely
9204 not relevant to policy; they should be treated as
9205 documentation for the packaging system. Please note that these
9206 appendices are included for convenience, and for historical
9207 reasons: they used to be part of policy package, and they have
9208 not yet been incorporated into dpkg documentation. However,
9209 they still have value, and hence they are presented here.
9213 They have not yet been checked to ensure that they are
9214 compatible with the contents of policy, and if there are any
9215 contradictions, the version in the main policy document takes
9216 precedence. The remaining chapters of the old Packaging
9217 Manual have also not been read in detail to ensure that there
9218 are not parts which have been left out. Both of these will be
9223 Certain parts of the Packaging manual were integrated into the
9224 Policy Manual proper, and removed from the appendices. Links
9225 have been placed from the old locations to the new ones.
9229 <prgn>dpkg</prgn> is a suite of programs for creating binary
9230 package files and installing and removing them on Unix
9232 <prgn>dpkg</prgn> is targeted primarily at Debian
9233 GNU/Linux, but may work on or be ported to other
9239 The binary packages are designed for the management of
9240 installed executable programs (usually compiled binaries) and
9241 their associated data, though source code examples and
9242 documentation are provided as part of some packages.</p>
9245 This manual describes the technical aspects of creating Debian
9246 binary packages (<file>.deb</file> files). It documents the
9247 behavior of the package management programs
9248 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9249 they interact with packages.</p>
9252 It also documents the interaction between
9253 <prgn>dselect</prgn>'s core and the access method scripts it
9254 uses to actually install the selected packages, and describes
9255 how to create a new access method.</p>
9258 This manual does not go into detail about the options and
9259 usage of the package building and installation tools. It
9260 should therefore be read in conjunction with those programs'
9265 The utility programs which are provided with <prgn>dpkg</prgn>
9266 for managing various system configuration and similar issues,
9267 such as <prgn>update-rc.d</prgn> and
9268 <prgn>install-info</prgn>, are not described in detail here -
9269 please see their man pages.
9273 It is assumed that the reader is reasonably familiar with the
9274 <prgn>dpkg</prgn> System Administrators' manual.
9275 Unfortunately this manual does not yet exist.
9279 The Debian version of the FSF's GNU hello program is provided
9280 as an example for people wishing to create Debian
9281 packages. The Debian <prgn>debmake</prgn> package is
9282 recommended as a very helpful tool in creating and maintaining
9283 Debian packages. However, while the tools and examples are
9284 helpful, they do not replace the need to read and follow the
9285 Policy and Programmer's Manual.</p>
9288 <appendix id="pkg-binarypkg">
9289 <heading>Binary packages (from old Packaging Manual)</heading>
9292 The binary package has two main sections. The first part
9293 consists of various control information files and scripts used
9294 by <prgn>dpkg</prgn> when installing and removing. See <ref
9295 id="pkg-controlarea">.
9299 The second part is an archive containing the files and
9300 directories to be installed.
9304 In the future binary packages may also contain other
9305 components, such as checksums and digital signatures. The
9306 format for the archive is described in full in the
9307 <file>deb(5)</file> man page.
9311 <sect id="pkg-bincreating"><heading>Creating package files -
9312 <prgn>dpkg-deb</prgn>
9316 All manipulation of binary package files is done by
9317 <prgn>dpkg-deb</prgn>; it's the only program that has
9318 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9319 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9320 will spot that the options requested are appropriate to
9321 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9326 In order to create a binary package you must make a
9327 directory tree which contains all the files and directories
9328 you want to have in the file system data part of the package.
9329 In Debian-format source packages this directory is usually
9330 <file>debian/tmp</file>, relative to the top of the package's
9335 They should have the locations (relative to the root of the
9336 directory tree you're constructing) ownerships and
9337 permissions which you want them to have on the system when
9342 With current versions of <prgn>dpkg</prgn> the uid/username
9343 and gid/groupname mappings for the users and groups being
9344 used should be the same on the system where the package is
9345 built and the one where it is installed.
9349 You need to add one special directory to the root of the
9350 miniature file system tree you're creating:
9351 <prgn>DEBIAN</prgn>. It should contain the control
9352 information files, notably the binary package control file
9353 (see <ref id="pkg-controlfile">).
9357 The <prgn>DEBIAN</prgn> directory will not appear in the
9358 file system archive of the package, and so won't be installed
9359 by <prgn>dpkg</prgn> when the package is installed.
9363 When you've prepared the package, you should invoke:
9365 dpkg --build <var>directory</var>
9370 This will build the package in
9371 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9372 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9373 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9378 See the man page <manref name="dpkg-deb" section="8"> for details of how
9379 to examine the contents of this newly-created file. You may find the
9380 output of following commands enlightening:
9382 dpkg-deb --info <var>filename</var>.deb
9383 dpkg-deb --contents <var>filename</var>.deb
9384 dpkg --contents <var>filename</var>.deb
9386 To view the copyright file for a package you could use this command:
9388 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9393 <sect id="pkg-controlarea">
9394 <heading>Package control information files</heading>
9397 The control information portion of a binary package is a
9398 collection of files with names known to <prgn>dpkg</prgn>.
9399 It will treat the contents of these files specially - some
9400 of them contain information used by <prgn>dpkg</prgn> when
9401 installing or removing the package; others are scripts which
9402 the package maintainer wants <prgn>dpkg</prgn> to run.
9406 It is possible to put other files in the package control
9407 area, but this is not generally a good idea (though they
9408 will largely be ignored).
9412 Here is a brief list of the control info files supported by
9413 <prgn>dpkg</prgn> and a summary of what they're used for.
9418 <tag><tt>control</tt>
9421 This is the key description file used by
9422 <prgn>dpkg</prgn>. It specifies the package's name
9423 and version, gives its description for the user,
9424 states its relationships with other packages, and so
9425 forth. See <ref id="sourcecontrolfiles"> and
9426 <ref id="binarycontrolfiles">.
9430 It is usually generated automatically from information
9431 in the source package by the
9432 <prgn>dpkg-gencontrol</prgn> program, and with
9433 assistance from <prgn>dpkg-shlibdeps</prgn>.
9434 See <ref id="pkg-sourcetools">.
9438 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9443 These are executable files (usually scripts) which
9444 <prgn>dpkg</prgn> runs during installation, upgrade
9445 and removal of packages. They allow the package to
9446 deal with matters which are particular to that package
9447 or require more complicated processing than that
9448 provided by <prgn>dpkg</prgn>. Details of when and
9449 how they are called are in <ref id="maintainerscripts">.
9453 It is very important to make these scripts idempotent.
9454 See <ref id="idempotency">.
9458 The maintainer scripts are guaranteed to run with a
9459 controlling terminal and can interact with the user.
9460 See <ref id="controllingterminal">.
9464 <tag><tt>conffiles</tt>
9467 This file contains a list of configuration files which
9468 are to be handled automatically by <prgn>dpkg</prgn>
9469 (see <ref id="pkg-conffiles">). Note that not necessarily
9470 every configuration file should be listed here.
9473 <tag><tt>shlibs</tt>
9476 This file contains a list of the shared libraries
9477 supplied by the package, with dependency details for
9478 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9479 when it determines what dependencies are required in a
9480 package control file. The <tt>shlibs</tt> file format
9481 is described on <ref id="shlibs">.
9486 <sect id="pkg-controlfile">
9487 <heading>The main control information file: <tt>control</tt></heading>
9490 The most important control information file used by
9491 <prgn>dpkg</prgn> when it installs a package is
9492 <tt>control</tt>. It contains all the package's "vital
9497 The binary package control files of packages built from
9498 Debian sources are made by a special tool,
9499 <prgn>dpkg-gencontrol</prgn>, which reads
9500 <file>debian/control</file> and <file>debian/changelog</file> to
9501 find the information it needs. See <ref id="pkg-sourcepkg"> for
9506 The fields in binary package control files are listed in
9507 <ref id="binarycontrolfiles">.
9511 A description of the syntax of control files and the purpose
9512 of the fields is available in <ref id="controlfields">.
9517 <heading>Time Stamps</heading>
9520 See <ref id="timestamps">.
9525 <appendix id="pkg-sourcepkg">
9526 <heading>Source packages (from old Packaging Manual) </heading>
9529 The Debian binary packages in the distribution are generated
9530 from Debian sources, which are in a special format to assist
9531 the easy and automatic building of binaries.
9534 <sect id="pkg-sourcetools">
9535 <heading>Tools for processing source packages</heading>
9538 Various tools are provided for manipulating source packages;
9539 they pack and unpack sources and help build of binary
9540 packages and help manage the distribution of new versions.
9544 They are introduced and typical uses described here; see
9545 <manref name="dpkg-source" section="1"> for full
9546 documentation about their arguments and operation.
9550 For examples of how to construct a Debian source package,
9551 and how to use those utilities that are used by Debian
9552 source packages, please see the <prgn>hello</prgn> example
9556 <sect1 id="pkg-dpkg-source">
9558 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9563 This program is frequently used by hand, and is also
9564 called from package-independent automated building scripts
9565 such as <prgn>dpkg-buildpackage</prgn>.
9569 To unpack a package it is typically invoked with
9571 dpkg-source -x <var>.../path/to/filename</var>.dsc
9576 with the <file><var>filename</var>.tar.gz</file> and
9577 <file><var>filename</var>.diff.gz</file> (if applicable) in
9578 the same directory. It unpacks into
9579 <file><var>package</var>-<var>version</var></file>, and if
9581 <file><var>package</var>-<var>version</var>.orig</file>, in
9582 the current directory.
9586 To create a packed source archive it is typically invoked:
9588 dpkg-source -b <var>package</var>-<var>version</var>
9593 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9594 <file>.diff.gz</file> (if appropriate) in the current
9595 directory. <prgn>dpkg-source</prgn> does not clean the
9596 source tree first - this must be done separately if it is
9601 See also <ref id="pkg-sourcearchives">.</p>
9605 <sect1 id="pkg-dpkg-buildpackage">
9607 <prgn>dpkg-buildpackage</prgn> - overall package-building
9612 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9613 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9614 targets <tt>clean</tt>, <tt>build</tt> and
9615 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9616 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9617 source and binary package upload.
9621 It is usually invoked by hand from the top level of the
9622 built or unbuilt source directory. It may be invoked with
9623 no arguments; useful arguments include:
9624 <taglist compact="compact">
9625 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9628 Do not sign the <tt>.changes</tt> file or the
9629 source package <tt>.dsc</tt> file, respectively.</p>
9631 <tag><tt>-p<var>sign-command</var></tt></tag>
9634 Invoke <var>sign-command</var> instead of finding
9635 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9636 <var>sign-command</var> must behave just like
9637 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9639 <tag><tt>-r<var>root-command</var></tt></tag>
9642 When root privilege is required, invoke the command
9643 <var>root-command</var>. <var>root-command</var>
9644 should invoke its first argument as a command, from
9645 the <prgn>PATH</prgn> if necessary, and pass its
9646 second and subsequent arguments to the command it
9647 calls. If no <var>root-command</var> is supplied
9648 then <var>dpkg-buildpackage</var> will take no
9649 special action to gain root privilege, so that for
9650 most packages it will have to be invoked as root to
9653 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9656 Two types of binary-only build and upload - see
9657 <manref name="dpkg-source" section="1">.
9664 <sect1 id="pkg-dpkg-gencontrol">
9666 <prgn>dpkg-gencontrol</prgn> - generates binary package
9671 This program is usually called from <file>debian/rules</file>
9672 (see <ref id="pkg-sourcetree">) in the top level of the source
9677 This is usually done just before the files and directories in the
9678 temporary directory tree where the package is being built have their
9679 permissions and ownerships set and the package is constructed using
9680 <prgn>dpkg-deb/</prgn>
9682 This is so that the control file which is produced has
9683 the right permissions
9688 <prgn>dpkg-gencontrol</prgn> must be called after all the
9689 files which are to go into the package have been placed in
9690 the temporary build directory, so that its calculation of
9691 the installed size of a package is correct.
9695 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9696 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9697 variable substitutions created by
9698 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9703 For a package which generates only one binary package, and
9704 which builds it in <file>debian/tmp</file> relative to the top
9705 of the source package, it is usually sufficient to call
9706 <prgn>dpkg-gencontrol</prgn>.
9710 Sources which build several binaries will typically need
9713 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9714 </example> The <tt>-P</tt> tells
9715 <prgn>dpkg-gencontrol</prgn> that the package is being
9716 built in a non-default directory, and the <tt>-p</tt>
9717 tells it which package's control file should be generated.
9721 <prgn>dpkg-gencontrol</prgn> also adds information to the
9722 list of files in <file>debian/files</file>, for the benefit of
9723 (for example) a future invocation of
9724 <prgn>dpkg-genchanges</prgn>.</p>
9727 <sect1 id="pkg-dpkg-shlibdeps">
9729 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9734 This program is usually called from <file>debian/rules</file>
9735 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9736 id="pkg-sourcetree">), in the top level of the source tree.
9740 Its arguments are executables and shared libraries
9743 They may be specified either in the locations in the
9744 source tree where they are created or in the locations
9745 in the temporary build tree where they are installed
9746 prior to binary package creation.
9748 </footnote> for which shared library dependencies should
9749 be included in the binary package's control file.
9753 If some of the found shared libraries should only
9754 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9755 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9756 by using the <tt>-d<var>dependency-field</var></tt> option
9757 before those executable(s). (Each <tt>-d</tt> option
9758 takes effect until the next <tt>-d</tt>.)
9762 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9763 output control file to be modified. Instead by default it
9764 adds to the <file>debian/substvars</file> file variable
9765 settings like <tt>shlibs:Depends</tt>. These variable
9766 settings must be referenced in dependency fields in the
9767 appropriate per-binary-package sections of the source
9772 For example, a package that generates an essential part
9773 which requires dependencies, and optional parts that
9774 which only require a recommendation, would separate those
9775 two sets of dependencies into two different fields.<footnote>
9776 At the time of writing, an example for this was the
9777 <package/xmms/ package, with Depends used for the xmms
9778 executable, Recommends for the plug-ins and Suggests for
9779 even more optional features provided by unzip.
9781 It can say in its <file>debian/rules</file>:
9783 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9784 -dRecommends <var>optionalpart anotheroptionalpart</var>
9786 and then in its main control file <file>debian/control</file>:
9789 Depends: ${shlibs:Depends}
9790 Recommends: ${shlibs:Recommends}
9796 Sources which produce several binary packages with
9797 different shared library dependency requirements can use
9798 the <tt>-p<var>varnameprefix</var></tt> option to override
9799 the default <tt>shlibs:</tt> prefix (one invocation of
9800 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9801 They can thus produce several sets of dependency
9802 variables, each of the form
9803 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9804 which can be referred to in the appropriate parts of the
9805 binary package control files.
9810 <sect1 id="pkg-dpkg-distaddfile">
9812 <prgn>dpkg-distaddfile</prgn> - adds a file to
9813 <file>debian/files</file>
9817 Some packages' uploads need to include files other than
9818 the source and binary package files.
9822 <prgn>dpkg-distaddfile</prgn> adds a file to the
9823 <file>debian/files</file> file so that it will be included in
9824 the <file>.changes</file> file when
9825 <prgn>dpkg-genchanges</prgn> is run.
9829 It is usually invoked from the <tt>binary</tt> target of
9830 <file>debian/rules</file>:
9832 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9834 The <var>filename</var> is relative to the directory where
9835 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9836 is usually the directory above the top level of the source
9837 tree. The <file>debian/rules</file> target should put the
9838 file there just before or just after calling
9839 <prgn>dpkg-distaddfile</prgn>.
9843 The <var>section</var> and <var>priority</var> are passed
9844 unchanged into the resulting <file>.changes</file> file.
9849 <sect1 id="pkg-dpkg-genchanges">
9851 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9856 This program is usually called by package-independent
9857 automatic building scripts such as
9858 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9863 It is usually called in the top level of a built source
9864 tree, and when invoked with no arguments will print out a
9865 straightforward <file>.changes</file> file based on the
9866 information in the source package's changelog and control
9867 file and the binary and source packages which should have
9873 <sect1 id="pkg-dpkg-parsechangelog">
9875 <prgn>dpkg-parsechangelog</prgn> - produces parsed
9876 representation of a changelog
9880 This program is used internally by
9881 <prgn>dpkg-source</prgn> et al. It may also occasionally
9882 be useful in <file>debian/rules</file> and elsewhere. It
9883 parses a changelog, <file>debian/changelog</file> by default,
9884 and prints a control-file format representation of the
9885 information in it to standard output.
9889 <sect1 id="pkg-dpkg-architecture">
9891 <prgn>dpkg-architecture</prgn> - information about the build and
9896 This program can be used manually, but is also invoked by
9897 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
9898 environment or make variables which specify the build and host
9899 architecture for the package building process.
9904 <sect id="pkg-sourcetree">
9905 <heading>The Debianised source tree</heading>
9908 The source archive scheme described later is intended to
9909 allow a Debianised source tree with some associated control
9910 information to be reproduced and transported easily. The
9911 Debianised source tree is a version of the original program
9912 with certain files added for the benefit of the
9913 Debianisation process, and with any other changes required
9914 made to the rest of the source code and installation
9919 The extra files created for Debian are in the subdirectory
9920 <file>debian</file> of the top level of the Debianised source
9921 tree. They are described below.
9924 <sect1 id="pkg-debianrules">
9925 <heading><file>debian/rules</file> - the main building script</heading>
9928 See <ref id="debianrules">.
9933 <sect1 id="pkg-dpkgchangelog">
9934 <heading><file>debian/changelog</file></heading>
9937 See <ref id="dpkgchangelog">.
9940 <sect2><heading>Defining alternative changelog formats
9944 It is possible to use a different format to the standard
9945 one, by providing a parser for the format you wish to
9950 In order to have <tt>dpkg-parsechangelog</tt> run your
9951 parser, you must include a line within the last 40 lines
9952 of your file matching the Perl regular expression:
9953 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9954 parentheses should be the name of the format. For
9955 example, you might say:
9957 @@@ changelog-format: joebloggs @@@
9959 Changelog format names are non-empty strings of alphanumerics.
9963 If such a line exists then <tt>dpkg-parsechangelog</tt>
9964 will look for the parser as
9965 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9967 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9968 it is an error for it not to find it, or for it not to
9969 be an executable program. The default changelog format
9970 is <tt>dpkg</tt>, and a parser for it is provided with
9971 the <tt>dpkg</tt> package.
9975 The parser will be invoked with the changelog open on
9976 standard input at the start of the file. It should read
9977 the file (it may seek if it wishes) to determine the
9978 information required and return the parsed information
9979 to standard output in the form of a series of control
9980 fields in the standard format. By default it should
9981 return information about only the most recent version in
9982 the changelog; it should accept a
9983 <tt>-v<var>version</var></tt> option to return changes
9984 information from all versions present <em>strictly
9985 after</em> <var>version</var>, and it should then be an
9986 error for <var>version</var> not to be present in the
9992 <list compact="compact">
9993 <item><qref id="f-Source"><tt>Source</tt></qref></item>
9994 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
9995 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
9996 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</item>
9997 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
9998 <item><qref id="f-Date"><tt>Date</tt></qref></item>
9999 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
10004 If several versions are being returned (due to the use
10005 of <tt>-v</tt>), the urgency value should be of the
10006 highest urgency code listed at the start of any of the
10007 versions requested followed by the concatenated
10008 (space-separated) comments from all the versions
10009 requested; the maintainer, version, distribution and
10010 date should always be from the most recent version.
10014 For the format of the <tt>Changes</tt> field see
10015 <ref id="f-Changes">.
10019 If the changelog format which is being parsed always or
10020 almost always leaves a blank line between individual
10021 change notes these blank lines should be stripped out,
10022 so as to make the resulting output compact.
10026 If the changelog format does not contain date or package
10027 name information this information should be omitted from
10028 the output. The parser should not attempt to synthesize
10029 it or find it from other sources.
10033 If the changelog does not have the expected format the
10034 parser should exit with a nonzero exit status, rather
10035 than trying to muddle through and possibly generating
10040 A changelog parser may not interact with the user at
10046 <sect1 id="pkg-srcsubstvars">
10047 <heading><file>debian/substvars</file> and variable substitutions</heading>
10050 See <ref id="substvars">.
10056 <heading><file>debian/files</file></heading>
10059 See <ref id="debianfiles">.
10063 <sect1><heading><file>debian/tmp</file>
10067 This is the canonical temporary location for the
10068 construction of binary packages by the <tt>binary</tt>
10069 target. The directory <file>tmp</file> serves as the root of
10070 the file system tree as it is being constructed (for
10071 example, by using the package's upstream makefiles install
10072 targets and redirecting the output there), and it also
10073 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10074 id="pkg-bincreating">.
10078 If several binary packages are generated from the same
10079 source tree it is usual to use several
10080 <file>debian/tmp<var>something</var></file> directories, for
10081 example <file>tmp-a</file> or <file>tmp-doc</file>.
10085 Whatever <file>tmp</file> directories are created and used by
10086 <tt>binary</tt> must of course be removed by the
10087 <tt>clean</tt> target.</p></sect1>
10091 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10095 As it exists on the FTP site, a Debian source package
10096 consists of three related files. You must have the right
10097 versions of all three to be able to use them.
10102 <tag>Debian source control file - <tt>.dsc</tt></tag>
10104 This file is a control file used by <prgn>dpkg-source</prgn>
10105 to extract a source package.
10106 See <ref id="debiansourcecontrolfiles">.
10110 Original source archive -
10112 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10118 This is a compressed (with <tt>gzip -9</tt>)
10119 <prgn>tar</prgn> file containing the source code from
10120 the upstream authors of the program.
10125 Debianisation diff -
10127 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10133 This is a unified context diff (<tt>diff -u</tt>)
10134 giving the changes which are required to turn the
10135 original source into the Debian source. These changes
10136 may only include editing and creating plain files.
10137 The permissions of files, the targets of symbolic
10138 links and the characteristics of special files or
10139 pipes may not be changed and no files may be removed
10144 All the directories in the diff must exist, except the
10145 <file>debian</file> subdirectory of the top of the source
10146 tree, which will be created by
10147 <prgn>dpkg-source</prgn> if necessary when unpacking.
10151 The <prgn>dpkg-source</prgn> program will
10152 automatically make the <file>debian/rules</file> file
10153 executable (see below).</p></item>
10158 If there is no original source code - for example, if the
10159 package is specially prepared for Debian or the Debian
10160 maintainer is the same as the upstream maintainer - the
10161 format is slightly different: then there is no diff, and the
10163 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10164 and preferably contains a directory named
10165 <file><var>package</var>-<var>version</var></file>.
10170 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10173 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10174 Debian source package. However, if it is not available it
10175 is possible to unpack a Debian source archive as follows:
10176 <enumlist compact="compact">
10179 Untar the tarfile, which will create a <file>.orig</file>
10183 <p>Rename the <file>.orig</file> directory to
10184 <file><var>package</var>-<var>version</var></file>.</p>
10188 Create the subdirectory <file>debian</file> at the top of
10189 the source tree.</p>
10191 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10193 <item><p>Untar the tarfile again if you want a copy of the original
10194 source code alongside the Debianised version.</p>
10199 It is not possible to generate a valid Debian source archive
10200 without using <prgn>dpkg-source</prgn>. In particular,
10201 attempting to use <prgn>diff</prgn> directly to generate the
10202 <file>.diff.gz</file> file will not work.
10206 <heading>Restrictions on objects in source packages</heading>
10209 The source package may not contain any hard links
10211 This is not currently detected when building source
10212 packages, but only when extracting
10216 Hard links may be permitted at some point in the
10217 future, but would require a fair amount of
10219 </footnote>, device special files, sockets or setuid or
10222 Setgid directories are allowed.
10227 The source packaging tools manage the changes between the
10228 original and Debianised source using <prgn>diff</prgn> and
10229 <prgn>patch</prgn>. Turning the original source tree as
10230 included in the <file>.orig.tar.gz</file> into the debianised
10231 source must not involve any changes which cannot be
10232 handled by these tools. Problematic changes which cause
10233 <prgn>dpkg-source</prgn> to halt with an error when
10234 building the source package are:
10235 <list compact="compact">
10236 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10238 <item><p>Changing the targets of symbolic links.</p>
10240 <item><p>Creating directories, other than <file>debian</file>.</p>
10242 <item><p>Changes to the contents of binary files.</p></item>
10243 </list> Changes which cause <prgn>dpkg-source</prgn> to
10244 print a warning but continue anyway are:
10245 <list compact="compact">
10248 Removing files, directories or symlinks.
10250 Renaming a file is not treated specially - it is
10251 seen as the removal of the old file (which
10252 generates a warning, but is otherwise ignored),
10253 and the creation of the new one.
10259 Changed text files which are missing the usual final
10260 newline (either in the original or the modified
10265 Changes which are not represented, but which are not detected by
10266 <prgn>dpkg-source</prgn>, are:
10267 <list compact="compact">
10268 <item><p>Changing the permissions of files (other than
10269 <file>debian/rules</file>) and directories.</p></item>
10274 The <file>debian</file> directory and <file>debian/rules</file>
10275 are handled specially by <prgn>dpkg-source</prgn> - before
10276 applying the changes it will create the <file>debian</file>
10277 directory, and afterwards it will make
10278 <file>debian/rules</file> world-executable.
10284 <appendix id="pkg-controlfields">
10285 <heading>Control files and their fields (from old Packaging Manual)</heading>
10288 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10289 data in a common format, known as control files. Binary and
10290 source packages have control data as do the <file>.changes</file>
10291 files which control the installation of uploaded files, and
10292 <prgn>dpkg</prgn>'s internal databases are in a similar
10297 <heading>Syntax of control files</heading>
10300 See <ref id="controlsyntax">.
10304 It is important to note that there are several fields which
10305 are optional as far as <prgn>dpkg</prgn> and the related
10306 tools are concerned, but which must appear in every Debian
10307 package, or whose omission may cause problems.
10312 <heading>List of fields</heading>
10315 See <ref id="controlfieldslist">.
10319 This section now contains only the fields that didn't belong
10320 to the Policy manual.
10323 <sect1 id="pkg-f-Filename">
10324 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10327 These fields in <tt>Packages</tt> files give the
10328 filename(s) of (the parts of) a package in the
10329 distribution directories, relative to the root of the
10330 Debian hierarchy. If the package has been split into
10331 several parts the parts are all listed in order, separated
10336 <sect1 id="pkg-f-Size">
10337 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10340 These fields in <file>Packages</file> files give the size (in
10341 bytes, expressed in decimal) and MD5 checksum of the
10342 file(s) which make(s) up a binary package in the
10343 distribution. If the package is split into several parts
10344 the values for the parts are listed in order, separated by
10349 <sect1 id="pkg-f-Status">
10350 <heading><tt>Status</tt></heading>
10353 This field in <prgn>dpkg</prgn>'s status file records
10354 whether the user wants a package installed, removed or
10355 left alone, whether it is broken (requiring
10356 re-installation) or not and what its current state on the
10357 system is. Each of these pieces of information is a
10362 <sect1 id="pkg-f-Config-Version">
10363 <heading><tt>Config-Version</tt></heading>
10366 If a package is not installed or not configured, this
10367 field in <prgn>dpkg</prgn>'s status file records the last
10368 version of the package which was successfully
10373 <sect1 id="pkg-f-Conffiles">
10374 <heading><tt>Conffiles</tt></heading>
10377 This field in <prgn>dpkg</prgn>'s status file contains
10378 information about the automatically-managed configuration
10379 files held by a package. This field should <em>not</em>
10380 appear anywhere in a package!
10385 <heading>Obsolete fields</heading>
10388 These are still recognized by <prgn>dpkg</prgn> but should
10389 not appear anywhere any more.
10391 <taglist compact="compact">
10393 <tag><tt>Revision</tt></tag>
10394 <tag><tt>Package-Revision</tt></tag>
10395 <tag><tt>Package_Revision</tt></tag>
10397 The Debian revision part of the package version was
10398 at one point in a separate control file field. This
10399 field went through several names.
10402 <tag><tt>Recommended</tt></tag>
10403 <item>Old name for <tt>Recommends</tt>.</item>
10405 <tag><tt>Optional</tt></tag>
10406 <item>Old name for <tt>Suggests</tt>.</item>
10408 <tag><tt>Class</tt></tag>
10409 <item>Old name for <tt>Priority</tt>.</item>
10418 <appendix id="pkg-conffiles">
10419 <heading>Configuration file handling (from old Packaging Manual)</heading>
10422 <prgn>dpkg</prgn> can do a certain amount of automatic
10423 handling of package configuration files.
10427 Whether this mechanism is appropriate depends on a number of
10428 factors, but basically there are two approaches to any
10429 particular configuration file.
10433 The easy method is to ship a best-effort configuration in the
10434 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10435 handle updates. If the user is unlikely to want to edit the
10436 file, but you need them to be able to without losing their
10437 changes, and a new package with a changed version of the file
10438 is only released infrequently, this is a good approach.
10442 The hard method is to build the configuration file from
10443 scratch in the <prgn>postinst</prgn> script, and to take the
10444 responsibility for fixing any mistakes made in earlier
10445 versions of the package automatically. This will be
10446 appropriate if the file is likely to need to be different on
10450 <sect><heading>Automatic handling of configuration files by
10455 A package may contain a control area file called
10456 <tt>conffiles</tt>. This file should be a list of filenames
10457 of configuration files needing automatic handling, separated
10458 by newlines. The filenames should be absolute pathnames,
10459 and the files referred to should actually exist in the
10464 When a package is upgraded <prgn>dpkg</prgn> will process
10465 the configuration files during the configuration stage,
10466 shortly before it runs the package's <prgn>postinst</prgn>
10471 For each file it checks to see whether the version of the
10472 file included in the package is the same as the one that was
10473 included in the last version of the package (the one that is
10474 being upgraded from); it also compares the version currently
10475 installed on the system with the one shipped with the last
10480 If neither the user nor the package maintainer has changed
10481 the file, it is left alone. If one or the other has changed
10482 their version, then the changed version is preferred - i.e.,
10483 if the user edits their file, but the package maintainer
10484 doesn't ship a different version, the user's changes will
10485 stay, silently, but if the maintainer ships a new version
10486 and the user hasn't edited it the new version will be
10487 installed (with an informative message). If both have
10488 changed their version the user is prompted about the problem
10489 and must resolve the differences themselves.
10493 The comparisons are done by calculating the MD5 message
10494 digests of the files, and storing the MD5 of the file as it
10495 was included in the most recent version of the package.
10499 When a package is installed for the first time
10500 <prgn>dpkg</prgn> will install the file that comes with it,
10501 unless that would mean overwriting a file already on the
10506 However, note that <prgn>dpkg</prgn> will <em>not</em>
10507 replace a conffile that was removed by the user (or by a
10508 script). This is necessary because with some programs a
10509 missing file produces an effect hard or impossible to
10510 achieve in another way, so that a missing file needs to be
10511 kept that way if the user did it.
10515 Note that a package should <em>not</em> modify a
10516 <prgn>dpkg</prgn>-handled conffile in its maintainer
10517 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10518 the user confusing and possibly dangerous options for
10519 conffile update when the package is upgraded.</p>
10522 <sect><heading>Fully-featured maintainer script configuration
10527 For files which contain site-specific information such as
10528 the hostname and networking details and so forth, it is
10529 better to create the file in the package's
10530 <prgn>postinst</prgn> script.
10534 This will typically involve examining the state of the rest
10535 of the system to determine values and other information, and
10536 may involve prompting the user for some information which
10537 can't be obtained some other way.
10541 When using this method there are a couple of important
10542 issues which should be considered:
10546 If you discover a bug in the program which generates the
10547 configuration file, or if the format of the file changes
10548 from one version to the next, you will have to arrange for
10549 the postinst script to do something sensible - usually this
10550 will mean editing the installed configuration file to remove
10551 the problem or change the syntax. You will have to do this
10552 very carefully, since the user may have changed the file,
10553 perhaps to fix the very problem that your script is trying
10554 to deal with - you will have to detect these situations and
10555 deal with them correctly.
10559 If you do go down this route it's probably a good idea to
10560 make the program that generates the configuration file(s) a
10561 separate program in <file>/usr/sbin</file>, by convention called
10562 <file><var>package</var>config</file> and then run that if
10563 appropriate from the post-installation script. The
10564 <tt><var>package</var>config</tt> program should not
10565 unquestioningly overwrite an existing configuration - if its
10566 mode of operation is geared towards setting up a package for
10567 the first time (rather than any arbitrary reconfiguration
10568 later) you should have it check whether the configuration
10569 already exists, and require a <tt>--force</tt> flag to
10570 overwrite it.</p></sect>
10573 <appendix id="pkg-alternatives"><heading>Alternative versions of
10574 an interface - <prgn>update-alternatives</prgn> (from old
10579 When several packages all provide different versions of the
10580 same program or file it is useful to have the system select a
10581 default, but to allow the system administrator to change it
10582 and have their decisions respected.
10586 For example, there are several versions of the <prgn>vi</prgn>
10587 editor, and there is no reason to prevent all of them from
10588 being installed at once, each under their own name
10589 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10590 Nevertheless it is desirable to have the name <tt>vi</tt>
10591 refer to something, at least by default.
10595 If all the packages involved cooperate, this can be done with
10596 <prgn>update-alternatives</prgn>.
10600 Each package provides its own version under its own name, and
10601 calls <prgn>update-alternatives</prgn> in its postinst to
10602 register its version (and again in its prerm to deregister
10607 See the man page <manref name="update-alternatives"
10608 section="8"> for details.
10612 If <prgn>update-alternatives</prgn> does not seem appropriate
10613 you may wish to consider using diversions instead.</p>
10616 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10617 package's version of a file (from old Packaging Manual)
10621 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10622 when it reinstalls the package it belongs to, and to have it
10623 put the file from the package somewhere else instead.
10627 This can be used locally to override a package's version of a
10628 file, or by one package to override another's version (or
10629 provide a wrapper for it).
10633 Before deciding to use a diversion, read <ref
10634 id="pkg-alternatives"> to see if you really want a diversion
10635 rather than several alternative versions of a program.
10639 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10640 and updated by a special program <prgn>dpkg-divert</prgn>.
10641 Please see <manref name="dpkg-divert" section="8"> for full
10642 details of its operation.
10646 When a package wishes to divert a file from another, it should
10647 call <prgn>dpkg-divert</prgn> in its preinst to add the
10648 diversion and rename the existing file. For example,
10649 supposing that a <prgn>smailwrapper</prgn> package wishes to
10650 install a wrapper around <file>/usr/sbin/smail</file>:
10652 dpkg-divert --package smailwrapper --add --rename \
10653 --divert /usr/sbin/smail.real /usr/sbin/smail
10654 </example> The <tt>--package smailwrapper</tt> ensures that
10655 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10656 can bypass the diversion and get installed as the true version.
10657 It's safe to add the diversion unconditionally on upgrades since
10658 it will be left unchanged if it already exists, but
10659 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10660 message, make the command conditional on the version from which
10661 the package is being upgraded:
10663 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10664 dpkg-divert --package smailwrapper --add --rename \
10665 --divert /usr/sbin/smail.real /usr/sbin/smail
10667 </example> where <tt>1.0-2</tt> is the version at which the
10668 diversion was first added to the package. Running the command
10669 during abort-upgrade is pointless but harmless.
10673 The postrm has to do the reverse:
10675 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10676 dpkg-divert --package smailwrapper --remove --rename \
10677 --divert /usr/sbin/smail.real /usr/sbin/smail
10679 </example> If the diversion was added at a particular version, the
10680 postrm should also handle the failure case of upgrading from an
10681 older version (unless the older version is so old that direct
10682 upgrades are no longer supported):
10684 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10685 dpkg-divert --package smailwrapper --remove --rename \
10686 --divert /usr/sbin/smail.real /usr/sbin/smail
10688 </example> where <tt>1.02-2</tt> is the version at which the
10689 diversion was first added to the package. The postrm should not
10690 remove the diversion on upgrades both because there's no reason to
10691 remove the diversion only to immediately re-add it and since the
10692 postrm of the old package is run after unpacking so the removal of
10693 the diversion will fail.
10697 Do not attempt to divert a file which is vitally important for
10698 the system's operation - when using <prgn>dpkg-divert</prgn>
10699 there is a time, after it has been diverted but before
10700 <prgn>dpkg</prgn> has installed the new version, when the file
10701 does not exist.</p>
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