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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 its
573 copyright information 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>,
692 <em>zope</em>. The additional section <em>debian-installer</em>
693 contains special packages used by the installer and is not used
694 for normal Debian packages.
698 For more information about the sections and their definitions,
699 see the <url id="http://packages.debian.org/unstable/"
700 name="list of sections in unstable">.
704 <sect id="priorities">
705 <heading>Priorities</heading>
708 Each package should have a <em>priority</em> value, which is
709 included in the package's <em>control record</em>
710 (see <ref id="f-Priority">).
711 This information is used by the Debian package management tools to
712 separate high-priority packages from less-important packages.
716 The following <em>priority levels</em> are recognized by the
717 Debian package management tools.
719 <tag><tt>required</tt></tag>
721 Packages which are necessary for the proper
722 functioning of the system (usually, this means that
723 dpkg functionality depends on these packages).
724 Removing a <tt>required</tt> package may cause your
725 system to become totally broken and you may not even
726 be able to use <prgn>dpkg</prgn> to put things back,
727 so only do so if you know what you are doing. Systems
728 with only the <tt>required</tt> packages are probably
729 unusable, but they do have enough functionality to
730 allow the sysadmin to boot and install more software.
732 <tag><tt>important</tt></tag>
734 Important programs, including those which one would
735 expect to find on any Unix-like system. If the
736 expectation is that an experienced Unix person who
737 found it missing would say "What on earth is going on,
738 where is <prgn>foo</prgn>?", it must be an
739 <tt>important</tt> package.<footnote>
740 This is an important criterion because we are
741 trying to produce, amongst other things, a free
744 Other packages without which the system will not run
745 well or be usable must also have priority
746 <tt>important</tt>. This does
747 <em>not</em> include Emacs, the X Window System, TeX
748 or any other large applications. The
749 <tt>important</tt> packages are just a bare minimum of
750 commonly-expected and necessary tools.
752 <tag><tt>standard</tt></tag>
754 These packages provide a reasonably small but not too
755 limited character-mode system. This is what will be
756 installed by default if the user doesn't select anything
757 else. It doesn't include many large applications.
759 <tag><tt>optional</tt></tag>
761 (In a sense everything that isn't required is
762 optional, but that's not what is meant here.) This is
763 all the software that you might reasonably want to
764 install if you didn't know what it was and don't have
765 specialized requirements. This is a much larger system
766 and includes the X Window System, a full TeX
767 distribution, and many applications. Note that
768 optional packages should not conflict with each other.
770 <tag><tt>extra</tt></tag>
772 This contains all packages that conflict with others
773 with required, important, standard or optional
774 priorities, or are only likely to be useful if you
775 already know what they are or have specialized
776 requirements (such as packages containing only detached
783 Packages must not depend on packages with lower priority
784 values (excluding build-time dependencies). In order to
785 ensure this, the priorities of one or more packages may need
794 <heading>Binary packages</heading>
797 The Debian GNU/Linux distribution is based on the Debian
798 package management system, called <prgn>dpkg</prgn>. Thus,
799 all packages in the Debian distribution must be provided
800 in the <tt>.deb</tt> file format.
804 <heading>The package name</heading>
807 Every package must have a name that's unique within the Debian
812 The package name is included in the control field
813 <tt>Package</tt>, the format of which is described
814 in <ref id="f-Package">.
815 The package name is also included as a part of the file name
816 of the <tt>.deb</tt> file.
821 <heading>The version of a package</heading>
824 Every package has a version number recorded in its
825 <tt>Version</tt> control file field, described in
826 <ref id="f-Version">.
830 The package management system imposes an ordering on version
831 numbers, so that it can tell whether packages are being up- or
832 downgraded and so that package system front end applications
833 can tell whether a package it finds available is newer than
834 the one installed on the system. The version number format
835 has the most significant parts (as far as comparison is
836 concerned) at the beginning.
840 If an upstream package has problematic version numbers they
841 should be converted to a sane form for use in the
842 <tt>Version</tt> field.
846 <heading>Version numbers based on dates</heading>
849 In general, Debian packages should use the same version
850 numbers as the upstream sources.
854 However, in some cases where the upstream version number is
855 based on a date (e.g., a development "snapshot" release) the
856 package management system cannot handle these version
857 numbers without epochs. For example, dpkg will consider
858 "96May01" to be greater than "96Dec24".
862 To prevent having to use epochs for every new upstream
863 version, the date based portion of the version number
864 should be changed to the following format in such cases:
865 "19960501", "19961224". It is up to the maintainer whether
866 they want to bother the upstream maintainer to change
867 the version numbers upstream, too.
871 Note that other version formats based on dates which are
872 parsed correctly by the package management system should
873 <em>not</em> be changed.
877 Native Debian packages (i.e., packages which have been
878 written especially for Debian) whose version numbers include
879 dates should always use the "YYYYMMDD" format.
886 <heading>The maintainer of a package</heading>
889 Every package must have a Debian maintainer (the
890 maintainer may be one person or a group of people
891 reachable from a common email address, such as a mailing
892 list). The maintainer is responsible for ensuring that
893 the package is placed in the appropriate distributions.
897 The maintainer must be specified in the
898 <tt>Maintainer</tt> control field with their correct name
899 and a working email address. If one person maintains
900 several packages, they should try to avoid having
901 different forms of their name and email address in
902 the <tt>Maintainer</tt> fields of those packages.
906 The format of the <tt>Maintainer</tt> control field is
907 described in <ref id="f-Maintainer">.
911 If the maintainer of a package quits from the Debian
912 project, "Debian QA Group"
913 <email>packages@qa.debian.org</email> takes over the
914 maintainer-ship of the package until someone else
915 volunteers for that task. These packages are called
916 <em>orphaned packages</em>.<footnote>
917 The detailed procedure for doing this gracefully can
918 be found in the Debian Developer's Reference,
919 see <ref id="related">.
924 <sect id="descriptions">
925 <heading>The description of a package</heading>
928 Every Debian package must have an extended description
929 stored in the appropriate field of the control record.
930 The technical information about the format of the
931 <tt>Description</tt> field is in <ref id="f-Description">.
935 The description should describe the package (the program) to a
936 user (system administrator) who has never met it before so that
937 they have enough information to decide whether they want to
938 install it. This description should not just be copied verbatim
939 from the program's documentation.
943 Put important information first, both in the synopsis and
944 extended description. Sometimes only the first part of the
945 synopsis or of the description will be displayed. You can
946 assume that there will usually be a way to see the whole
947 extended description.
951 The description should also give information about the
952 significant dependencies and conflicts between this package
953 and others, so that the user knows why these dependencies and
954 conflicts have been declared.
958 Instructions for configuring or using the package should
959 not be included (that is what installation scripts,
960 manual pages, info files, etc., are for). Copyright
961 statements and other administrivia should not be included
962 either (that is what the copyright file is for).
965 <sect1 id="synopsis"><heading>The single line synopsis</heading>
968 The single line synopsis should be kept brief - certainly
973 Do not include the package name in the synopsis line. The
974 display software knows how to display this already, and you
975 do not need to state it. Remember that in many situations
976 the user may only see the synopsis line - make it as
977 informative as you can.
982 <sect1 id="extendeddesc"><heading>The extended description</heading>
985 Do not try to continue the single line synopsis into the
986 extended description. This will not work correctly when
987 the full description is displayed, and makes no sense
988 where only the summary (the single line synopsis) is
993 The extended description should describe what the package
994 does and how it relates to the rest of the system (in terms
995 of, for example, which subsystem it is which part of).
999 The description field needs to make sense to anyone, even
1000 people who have no idea about any of the things the
1001 package deals with.<footnote>
1002 The blurb that comes with a program in its
1003 announcements and/or <prgn>README</prgn> files is
1004 rarely suitable for use in a description. It is
1005 usually aimed at people who are already in the
1006 community where the package is used.
1015 <heading>Dependencies</heading>
1018 Every package must specify the dependency information
1019 about other packages that are required for the first to
1024 For example, a dependency entry must be provided for any
1025 shared libraries required by a dynamically-linked executable
1026 binary in a package.
1030 Packages are not required to declare any dependencies they
1031 have on other packages which are marked <tt>Essential</tt>
1032 (see below), and should not do so unless they depend on a
1033 particular version of that package.<footnote>
1035 Essential is needed in part to avoid unresolvable dependency
1036 loops on upgrade. If packages add unnecessary dependencies
1037 on packages in this set, the chances that there
1038 <strong>will</strong> be an unresolvable dependency loop
1039 caused by forcing these Essential packages to be configured
1040 first before they need to be is greatly increased. It also
1041 increases the chances that frontends will be unable to
1042 <strong>calculate</strong> an upgrade path, even if one
1046 Also, functionality is rarely ever removed from the
1047 Essential set, but <em>packages</em> have been removed from
1048 the Essential set when the functionality moved to a
1049 different package. So depending on these packages <em>just
1050 in case</em> they stop being essential does way more harm
1057 Sometimes, a package requires another package to be installed
1058 <em>and</em> configured before it can be installed. In this
1059 case, you must specify a <tt>Pre-Depends</tt> entry for
1064 You should not specify a <tt>Pre-Depends</tt> entry for a
1065 package before this has been discussed on the
1066 <tt>debian-devel</tt> mailing list and a consensus about
1067 doing that has been reached.
1071 The format of the package interrelationship control fields is
1072 described in <ref id="relationships">.
1076 <sect id="virtual_pkg">
1077 <heading>Virtual packages</heading>
1080 Sometimes, there are several packages which offer
1081 more-or-less the same functionality. In this case, it's
1082 useful to define a <em>virtual package</em> whose name
1083 describes that common functionality. (The virtual
1084 packages only exist logically, not physically; that's why
1085 they are called <em>virtual</em>.) The packages with this
1086 particular function will then <em>provide</em> the virtual
1087 package. Thus, any other package requiring that function
1088 can simply depend on the virtual package without having to
1089 specify all possible packages individually.
1093 All packages should use virtual package names where
1094 appropriate, and arrange to create new ones if necessary.
1095 They should not use virtual package names (except privately,
1096 amongst a cooperating group of packages) unless they have
1097 been agreed upon and appear in the list of virtual package
1098 names. (See also <ref id="virtual">)
1102 The latest version of the authoritative list of virtual
1103 package names can be found in the <tt>debian-policy</tt> package.
1104 It is also available from the Debian web mirrors at
1105 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1106 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1110 The procedure for updating the list is described in the preface
1117 <heading>Base system</heading>
1120 The <tt>base system</tt> is a minimum subset of the Debian
1121 GNU/Linux system that is installed before everything else
1122 on a new system. Only very few packages are allowed to form
1123 part of the base system, in order to keep the required disk
1128 The base system consists of all those packages with priority
1129 <tt>required</tt> or <tt>important</tt>. Many of them will
1130 be tagged <tt>essential</tt> (see below).
1135 <heading>Essential packages</heading>
1138 Essential is defined as the minimal set of functionality that
1139 must be available and usable on the system at all times, even
1140 when packages are in an unconfigured (but unpacked) state.
1141 Packages are tagged <tt>essential</tt> for a system using the
1142 <tt>Essential</tt> control file field. The format of the
1143 <tt>Essential</tt> control field is described in <ref
1148 Since these packages cannot be easily removed (one has to
1149 specify an extra <em>force option</em> to
1150 <prgn>dpkg</prgn> to do so), this flag must not be used
1151 unless absolutely necessary. A shared library package
1152 must not be tagged <tt>essential</tt>; dependencies will
1153 prevent its premature removal, and we need to be able to
1154 remove it when it has been superseded.
1158 Since dpkg will not prevent upgrading of other packages
1159 while an <tt>essential</tt> package is in an unconfigured
1160 state, all <tt>essential</tt> packages must supply all of
1161 their core functionality even when unconfigured. If the
1162 package cannot satisfy this requirement it must not be
1163 tagged as essential, and any packages depending on this
1164 package must instead have explicit dependency fields as
1169 Maintainers should take great care in adding any programs,
1170 interfaces, or functionality to <tt>essential</tt> packages.
1171 Packages may assume that functionality provided by
1172 <tt>essential</tt> packages is always available without
1173 declaring explicit dependencies, which means that removing
1174 functionality from the Essential set is very difficult and is
1175 almost never done. Any capability added to an
1176 <tt>essential</tt> package therefore creates an obligation to
1177 support that capability as part of the Essential set in
1182 You must not tag any packages <tt>essential</tt> before
1183 this has been discussed on the <tt>debian-devel</tt>
1184 mailing list and a consensus about doing that has been
1189 <sect id="maintscripts">
1190 <heading>Maintainer Scripts</heading>
1193 The package installation scripts should avoid producing
1194 output which is unnecessary for the user to see and
1195 should rely on <prgn>dpkg</prgn> to stave off boredom on
1196 the part of a user installing many packages. This means,
1197 amongst other things, using the <tt>--quiet</tt> option on
1198 <prgn>install-info</prgn>.
1202 Errors which occur during the execution of an installation
1203 script must be checked and the installation must not
1204 continue after an error.
1208 Note that in general <ref id="scripts"> applies to package
1209 maintainer scripts, too.
1213 You should not use <prgn>dpkg-divert</prgn> on a file
1214 belonging to another package without consulting the
1215 maintainer of that package first.
1219 All packages which supply an instance of a common command
1220 name (or, in general, filename) should generally use
1221 <prgn>update-alternatives</prgn>, so that they may be
1222 installed together. If <prgn>update-alternatives</prgn>
1223 is not used, then each package must use
1224 <tt>Conflicts</tt> to ensure that other packages are
1225 de-installed. (In this case, it may be appropriate to
1226 specify a conflict against earlier versions of something
1227 that previously did not use
1228 <prgn>update-alternatives</prgn>; this is an exception to
1229 the usual rule that versioned conflicts should be
1233 <sect1 id="maintscriptprompt">
1234 <heading>Prompting in maintainer scripts</heading>
1236 Package maintainer scripts may prompt the user if
1237 necessary. Prompting must be done by communicating
1238 through a program, such as <prgn>debconf</prgn>, which
1239 conforms to the Debian Configuration Management
1240 Specification, version 2 or higher.
1244 Packages which are essential, or which are dependencies of
1245 essential packages, may fall back on another prompting method
1246 if no such interface is available when they are executed.
1250 The Debian Configuration Management Specification is included
1251 in the <file>debconf_specification</file> files in the
1252 <package>debian-policy</package> package.
1253 It is also available from the Debian web mirrors at
1254 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1255 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1259 Packages which use the Debian Configuration Management
1260 Specification may contain an additional
1261 <prgn>config</prgn> script and a <tt>templates</tt>
1262 file in their control archive<footnote>
1263 The control.tar.gz inside the .deb.
1264 See <manref name="deb" section="5">.
1266 The <prgn>config</prgn> script might be run before the
1267 <prgn>preinst</prgn> script, and before the package is unpacked
1268 or any of its dependencies or pre-dependencies are satisfied.
1269 Therefore it must work using only the tools present in
1270 <em>essential</em> packages.<footnote>
1271 <package>Debconf</package> or another tool that
1272 implements the Debian Configuration Management
1273 Specification will also be installed, and any
1274 versioned dependencies on it will be satisfied
1275 before preconfiguration begins.
1280 Packages which use the Debian Configuration Management
1281 Specification must allow for translation of their user-visible
1282 messages by using a gettext-based system such as the one
1283 provided by the <package>po-debconf</package> package.
1287 Packages should try to minimize the amount of prompting
1288 they need to do, and they should ensure that the user
1289 will only ever be asked each question once. This means
1290 that packages should try to use appropriate shared
1291 configuration files (such as <file>/etc/papersize</file> and
1292 <file>/etc/news/server</file>), and shared
1293 <package>debconf</package> variables rather than each
1294 prompting for their own list of required pieces of
1299 It also means that an upgrade should not ask the same
1300 questions again, unless the user has used
1301 <tt>dpkg --purge</tt> to remove the package's configuration.
1302 The answers to configuration questions should be stored in an
1303 appropriate place in <file>/etc</file> so that the user can
1304 modify them, and how this has been done should be
1309 If a package has a vitally important piece of
1310 information to pass to the user (such as "don't run me
1311 as I am, you must edit the following configuration files
1312 first or you risk your system emitting badly-formatted
1313 messages"), it should display this in the
1314 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1315 prompt the user to hit return to acknowledge the
1316 message. Copyright messages do not count as vitally
1317 important (they belong in
1318 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1319 neither do instructions on how to use a program (these
1320 should be in on-line documentation, where all the users
1325 Any necessary prompting should almost always be confined
1326 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1327 script. If it is done in the <prgn>postinst</prgn>, it
1328 should be protected with a conditional so that
1329 unnecessary prompting doesn't happen if a package's
1330 installation fails and the <prgn>postinst</prgn> is
1331 called with <tt>abort-upgrade</tt>,
1332 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1342 <heading>Source packages</heading>
1344 <sect id="standardsversion">
1345 <heading>Standards conformance</heading>
1348 Source packages should specify the most recent version number
1349 of this policy document with which your package complied
1350 when it was last updated.
1354 This information may be used to file bug reports
1355 automatically if your package becomes too much out of date.
1359 The version is specified in the <tt>Standards-Version</tt>
1361 The format of the <tt>Standards-Version</tt> field is
1362 described in <ref id="f-Standards-Version">.
1366 You should regularly, and especially if your package has
1367 become out of date, check for the newest Policy Manual
1368 available and update your package, if necessary. When your
1369 package complies with the new standards you should update the
1370 <tt>Standards-Version</tt> source package field and
1371 release it.<footnote>
1372 See the file <file>upgrading-checklist</file> for
1373 information about policy which has changed between
1374 different versions of this document.
1380 <sect id="pkg-relations">
1381 <heading>Package relationships</heading>
1384 Source packages should specify which binary packages they
1385 require to be installed or not to be installed in order to
1386 build correctly. For example, if building a package
1387 requires a certain compiler, then the compiler should be
1388 specified as a build-time dependency.
1392 It is not necessary to explicitly specify build-time
1393 relationships on a minimal set of packages that are always
1394 needed to compile, link and put in a Debian package a
1395 standard "Hello World!" program written in C or C++. The
1396 required packages are called <em>build-essential</em>, and
1397 an informational list can be found in
1398 <file>/usr/share/doc/build-essential/list</file> (which is
1399 contained in the <tt>build-essential</tt>
1402 <list compact="compact">
1404 This allows maintaining the list separately
1405 from the policy documents (the list does not
1406 need the kind of control that the policy
1410 Having a separate package allows one to install
1411 the build-essential packages on a machine, as
1412 well as allowing other packages such as tasks to
1413 require installation of the build-essential
1414 packages using the depends relation.
1417 The separate package allows bug reports against
1418 the list to be categorized separately from
1419 the policy management process in the BTS.
1426 When specifying the set of build-time dependencies, one
1427 should list only those packages explicitly required by the
1428 build. It is not necessary to list packages which are
1429 required merely because some other package in the list of
1430 build-time dependencies depends on them.<footnote>
1431 The reason for this is that dependencies change, and
1432 you should list all those packages, and <em>only</em>
1433 those packages that <em>you</em> need directly. What
1434 others need is their business. For example, if you
1435 only link against <file>libimlib</file>, you will need to
1436 build-depend on <package>libimlib2-dev</package> but
1437 not against any <tt>libjpeg*</tt> packages, even
1438 though <tt>libimlib2-dev</tt> currently depends on
1439 them: installation of <package>libimlib2-dev</package>
1440 will automatically ensure that all of its run-time
1441 dependencies are satisfied.
1446 If build-time dependencies are specified, it must be
1447 possible to build the package and produce working binaries
1448 on a system with only essential and build-essential
1449 packages installed and also those required to satisfy the
1450 build-time relationships (including any implied
1451 relationships). In particular, this means that version
1452 clauses should be used rigorously in build-time
1453 relationships so that one cannot produce bad or
1454 inconsistently configured packages when the relationships
1455 are properly satisfied.
1459 <ref id="relationships"> explains the technical details.
1464 <heading>Changes to the upstream sources</heading>
1467 If changes to the source code are made that are not
1468 specific to the needs of the Debian system, they should be
1469 sent to the upstream authors in whatever form they prefer
1470 so as to be included in the upstream version of the
1475 If you need to configure the package differently for
1476 Debian or for Linux, and the upstream source doesn't
1477 provide a way to do so, you should add such configuration
1478 facilities (for example, a new <prgn>autoconf</prgn> test
1479 or <tt>#define</tt>) and send the patch to the upstream
1480 authors, with the default set to the way they originally
1481 had it. You can then easily override the default in your
1482 <file>debian/rules</file> or wherever is appropriate.
1486 You should make sure that the <prgn>configure</prgn> utility
1487 detects the correct architecture specification string
1488 (refer to <ref id="arch-spec"> for details).
1492 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1493 <prgn>configure</prgn> scripts are used, you should edit the
1494 <file>.in</file> files rather than editing the
1495 <prgn>Makefile</prgn> directly. This allows the user to
1496 reconfigure the package if necessary. You should
1497 <em>not</em> configure the package and edit the generated
1498 <prgn>Makefile</prgn>! This makes it impossible for someone
1499 else to later reconfigure the package without losing the
1505 <sect id="dpkgchangelog">
1506 <heading>Debian changelog: <file>debian/changelog</file></heading>
1509 Changes in the Debian version of the package should be
1510 briefly explained in the Debian changelog file
1511 <file>debian/changelog</file>.<footnote>
1513 Mistakes in changelogs are usually best rectified by
1514 making a new changelog entry rather than "rewriting
1515 history" by editing old changelog entries.
1518 This includes modifications
1519 made in the Debian package compared to the upstream one
1520 as well as other changes and updates to the package.
1522 Although there is nothing stopping an author who is also
1523 the Debian maintainer from using this changelog for all
1524 their changes, it will have to be renamed if the Debian
1525 and upstream maintainers become different people. In such
1526 a case, however, it might be better to maintain the package
1527 as a non-native package.
1532 The format of the <file>debian/changelog</file> allows the
1533 package building tools to discover which version of the package
1534 is being built and find out other release-specific information.
1538 That format is a series of entries like this:
1540 <example compact="compact">
1541 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1543 [optional blank line(s), stripped]
1545 * <var>change details</var>
1546 <var>more change details</var>
1548 [blank line(s), included in output of dpkg-parsechangelog]
1550 * <var>even more change details</var>
1552 [optional blank line(s), stripped]
1554 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1559 <var>package</var> and <var>version</var> are the source
1560 package name and version number.
1564 <var>distribution(s)</var> lists the distributions where
1565 this version should be installed when it is uploaded - it
1566 is copied to the <tt>Distribution</tt> field in the
1567 <file>.changes</file> file. See <ref id="f-Distribution">.
1571 <var>urgency</var> is the value for the <tt>Urgency</tt>
1572 field in the <file>.changes</file> file for the upload
1573 (see <ref id="f-Urgency">). It is not possible to specify
1574 an urgency containing commas; commas are used to separate
1575 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1576 <prgn>dpkg</prgn> changelog format (though there is
1577 currently only one useful <var>keyword</var>,
1582 The change details may in fact be any series of lines
1583 starting with at least two spaces, but conventionally each
1584 change starts with an asterisk and a separating space and
1585 continuation lines are indented so as to bring them in
1586 line with the start of the text above. Blank lines may be
1587 used here to separate groups of changes, if desired.
1591 If this upload resolves bugs recorded in the Bug Tracking
1592 System (BTS), they may be automatically closed on the
1593 inclusion of this package into the Debian archive by
1594 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1595 in the change details.<footnote>
1596 To be precise, the string should match the following
1597 Perl regular expression:
1599 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1601 Then all of the bug numbers listed will be closed by the
1602 archive maintenance script (<prgn>katie</prgn>) using the
1603 <var>version</var> of the changelog entry.
1605 This information is conveyed via the <tt>Closes</tt> field
1606 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1610 The maintainer name and email address used in the changelog
1611 should be the details of the person uploading <em>this</em>
1612 version. They are <em>not</em> necessarily those of the
1613 usual package maintainer. The information here will be
1614 copied to the <tt>Changed-By</tt> field in the
1615 <tt>.changes</tt> file (see <ref id="f-Changed-By">),
1616 and then later used to send an acknowledgement when the
1617 upload has been installed.
1621 The <var>date</var> has the following format<footnote>
1622 This is generated by <tt>date -R</tt>.
1623 </footnote> (compatible and with the same semantics of
1624 RFC 2822 and RFC 5322):
1625 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1627 <list compact="compact">
1628 <item>day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun</item>
1629 <item>dd is a one- or two-digit day of the month (01-31)</item>
1630 <item>month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec</item>
1631 <item>yyyy is the four-digit year (e.g. 2010)</item>
1632 <item>hh is the two-digit hour (00-23</item>
1633 <item>mm is the two-digit minutes (00-59)</item>
1634 <item>ss is the two-digit seconds (00-60)</item>
1636 +zzzz or -zzzz is the the time zone offset from Coordinated Universal
1637 Time (UTC). "+" indicates that the time is ahead of (i.e., east of) UTC
1638 and "-" indicates that the time is behind (i.e., west of) UTC. The
1639 first two digits indicate the hour difference from UTC and the last
1640 two digits indicate the number of additional minutes difference from
1641 UTC. The last two digits must be in the range 00-59.
1647 The first "title" line with the package name must start
1648 at the left hand margin. The "trailer" line with the
1649 maintainer and date details must be preceded by exactly
1650 one space. The maintainer details and the date must be
1651 separated by exactly two spaces.
1655 The entire changelog must be encoded in UTF-8.
1659 For more information on placement of the changelog files
1660 within binary packages, please see <ref id="changelogs">.
1664 <sect id="dpkgcopyright">
1665 <heading>Copyright: <file>debian/copyright</file></heading>
1667 Every package must be accompanied by a verbatim copy of its
1668 copyright information and distribution license in the file
1669 <file>/usr/share/doc/<var>package</var>/copyright</file>
1670 (see <ref id="copyrightfile"> for further details). Also see
1671 <ref id="pkgcopyright"> for further considerations related
1672 to copyrights for packages.
1676 <heading>Error trapping in makefiles</heading>
1679 When <prgn>make</prgn> invokes a command in a makefile
1680 (including your package's upstream makefiles and
1681 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1682 means that <prgn>sh</prgn>'s usual bad error handling
1683 properties apply: if you include a miniature script as one
1684 of the commands in your makefile you'll find that if you
1685 don't do anything about it then errors are not detected
1686 and <prgn>make</prgn> will blithely continue after
1691 Every time you put more than one shell command (this
1692 includes using a loop) in a makefile command you
1693 must make sure that errors are trapped. For
1694 simple compound commands, such as changing directory and
1695 then running a program, using <tt>&&</tt> rather
1696 than semicolon as a command separator is sufficient. For
1697 more complex commands including most loops and
1698 conditionals you should include a separate <tt>set -e</tt>
1699 command at the start of every makefile command that's
1700 actually one of these miniature shell scripts.
1704 <sect id="timestamps">
1705 <heading>Time Stamps</heading>
1707 Maintainers should preserve the modification times of the
1708 upstream source files in a package, as far as is reasonably
1710 The rationale is that there is some information conveyed
1711 by knowing the age of the file, for example, you could
1712 recognize that some documentation is very old by looking
1713 at the modification time, so it would be nice if the
1714 modification time of the upstream source would be
1720 <sect id="restrictions">
1721 <heading>Restrictions on objects in source packages</heading>
1724 The source package may not contain any hard links<footnote>
1726 This is not currently detected when building source
1727 packages, but only when extracting
1731 Hard links may be permitted at some point in the
1732 future, but would require a fair amount of
1735 </footnote>, device special files, sockets or setuid or
1736 setgid files.<footnote>
1737 Setgid directories are allowed.
1742 <sect id="debianrules">
1743 <heading>Main building script: <file>debian/rules</file></heading>
1746 This file must be an executable makefile, and contains the
1747 package-specific recipes for compiling the package and
1748 building binary package(s) from the source.
1752 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1753 so that it can be invoked by saying its name rather than
1754 invoking <prgn>make</prgn> explicitly. That is, invoking
1755 either of <tt>make -f debian/rules <em>args...</em></tt>
1756 or <tt>./debian/rules <em>args...</em></tt> must result in
1761 Since an interactive <file>debian/rules</file> script makes it
1762 impossible to auto-compile that package and also makes it
1763 hard for other people to reproduce the same binary
1764 package, all <em>required targets</em> must be
1765 non-interactive. At a minimum, required targets are the
1766 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1767 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1768 <em>binary-indep</em>, and <em>build</em>. It also follows
1769 that any target that these targets depend on must also be
1774 The targets are as follows (required unless stated otherwise):
1776 <tag><tt>build</tt></tag>
1779 The <tt>build</tt> target should perform all the
1780 configuration and compilation of the package.
1781 If a package has an interactive pre-build
1782 configuration routine, the Debianized source package
1783 must either be built after this has taken place (so
1784 that the binary package can be built without rerunning
1785 the configuration) or the configuration routine
1786 modified to become non-interactive. (The latter is
1787 preferable if there are architecture-specific features
1788 detected by the configuration routine.)
1792 For some packages, notably ones where the same
1793 source tree is compiled in different ways to produce
1794 two binary packages, the <tt>build</tt> target
1795 does not make much sense. For these packages it is
1796 good enough to provide two (or more) targets
1797 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1798 for each of the ways of building the package, and a
1799 <tt>build</tt> target that does nothing. The
1800 <tt>binary</tt> target will have to build the
1801 package in each of the possible ways and make the
1802 binary package out of each.
1806 The <tt>build</tt> target must not do anything
1807 that might require root privilege.
1811 The <tt>build</tt> target may need to run the
1812 <tt>clean</tt> target first - see below.
1816 When a package has a configuration and build routine
1817 which takes a long time, or when the makefiles are
1818 poorly designed, or when <tt>build</tt> needs to
1819 run <tt>clean</tt> first, it is a good idea to
1820 <tt>touch build</tt> when the build process is
1821 complete. This will ensure that if <tt>debian/rules
1822 build</tt> is run again it will not rebuild the whole
1824 Another common way to do this is for <tt>build</tt>
1825 to depend on <prgn>build-stamp</prgn> and to do
1826 nothing else, and for the <prgn>build-stamp</prgn>
1827 target to do the building and to <tt>touch
1828 build-stamp</tt> on completion. This is
1829 especially useful if the build routine creates a
1830 file or directory called <tt>build</tt>; in such a
1831 case, <tt>build</tt> will need to be listed as
1832 a phony target (i.e., as a dependency of the
1833 <tt>.PHONY</tt> target). See the documentation of
1834 <prgn>make</prgn> for more information on phony
1840 <tag><tt>build-arch</tt> (optional),
1841 <tt>build-indep</tt> (optional)
1845 A package may also provide both of the targets
1846 <tt>build-arch</tt> and <tt>build-indep</tt>.
1847 The <tt>build-arch</tt> target, if provided, should
1848 perform all the configuration and compilation required
1849 for producing all architecture-dependant binary packages
1850 (those packages for which the body of the
1851 <tt>Architecture</tt> field in <tt>debian/control</tt>
1852 is not <tt>all</tt>).
1853 Similarly, the <tt>build-indep</tt> target, if
1854 provided, should perform all the configuration and
1855 compilation required for producing all
1856 architecture-independent binary packages
1857 (those packages for which the body of the
1858 <tt>Architecture</tt> field in <tt>debian/control</tt>
1860 The <tt>build</tt> target should depend on those of the
1861 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1862 are provided in the rules file.
1866 If one or both of the targets <tt>build-arch</tt> and
1867 <tt>build-indep</tt> are not provided, then invoking
1868 <file>debian/rules</file> with one of the not-provided
1869 targets as arguments should produce a exit status code
1870 of 2. Usually this is provided automatically by make
1871 if the target is missing.
1875 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1876 must not do anything that might require root privilege.
1880 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1881 <tt>binary-indep</tt>
1885 The <tt>binary</tt> target must be all that is
1886 necessary for the user to build the binary package(s)
1887 produced from this source package. It is
1888 split into two parts: <prgn>binary-arch</prgn> builds
1889 the binary packages which are specific to a particular
1890 architecture, and <tt>binary-indep</tt> builds
1891 those which are not.
1894 <tt>binary</tt> may be (and commonly is) a target with
1895 no commands which simply depends on
1896 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1899 Both <tt>binary-*</tt> targets should depend on the
1900 <tt>build</tt> target, or on the appropriate
1901 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1902 provided, so that the package is built if it has not
1903 been already. It should then create the relevant
1904 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1905 make their control files and <prgn>dpkg-deb</prgn> to
1906 build them and place them in the parent of the top
1911 Both the <tt>binary-arch</tt> and
1912 <tt>binary-indep</tt> targets <em>must</em> exist.
1913 If one of them has nothing to do (which will always be
1914 the case if the source generates only a single binary
1915 package, whether architecture-dependent or not), it
1916 must still exist and must always succeed.
1920 The <tt>binary</tt> targets must be invoked as
1922 The <prgn>fakeroot</prgn> package often allows one
1923 to build a package correctly even without being
1929 <tag><tt>clean</tt></tag>
1932 This must undo any effects that the <tt>build</tt>
1933 and <tt>binary</tt> targets may have had, except
1934 that it should leave alone any output files created in
1935 the parent directory by a run of a <tt>binary</tt>
1940 If a <tt>build</tt> file is touched at the end of
1941 the <tt>build</tt> target, as suggested above, it
1942 should be removed as the first action that
1943 <tt>clean</tt> performs, so that running
1944 <tt>build</tt> again after an interrupted
1945 <tt>clean</tt> doesn't think that everything is
1950 The <tt>clean</tt> target may need to be
1951 invoked as root if <tt>binary</tt> has been
1952 invoked since the last <tt>clean</tt>, or if
1953 <tt>build</tt> has been invoked as root (since
1954 <tt>build</tt> may create directories, for
1959 <tag><tt>get-orig-source</tt> (optional)</tag>
1962 This target fetches the most recent version of the
1963 original source package from a canonical archive site
1964 (via FTP or WWW, for example), does any necessary
1965 rearrangement to turn it into the original source
1966 tar file format described below, and leaves it in the
1971 This target may be invoked in any directory, and
1972 should take care to clean up any temporary files it
1977 This target is optional, but providing it if
1978 possible is a good idea.
1982 <tag><tt>patch</tt> (optional)</tag>
1985 This target performs whatever additional actions are
1986 required to make the source ready for editing (unpacking
1987 additional upstream archives, applying patches, etc.).
1988 It is recommended to be implemented for any package where
1989 <tt>dpkg-source -x</tt> does not result in source ready
1990 for additional modification. See
1991 <ref id="readmesource">.
1997 The <tt>build</tt>, <tt>binary</tt> and
1998 <tt>clean</tt> targets must be invoked with the current
1999 directory being the package's top-level directory.
2004 Additional targets may exist in <file>debian/rules</file>,
2005 either as published or undocumented interfaces or for the
2006 package's internal use.
2010 The architectures we build on and build for are determined
2011 by <prgn>make</prgn> variables using the utility
2012 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2013 You can determine the
2014 Debian architecture and the GNU style architecture
2015 specification string for the build machine (the machine type
2016 we are building on) as well as for the host machine (the
2017 machine type we are building for). Here is a list of
2018 supported <prgn>make</prgn> variables:
2019 <list compact="compact">
2021 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2024 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2027 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2030 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2031 specification string)
2034 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2035 <tt>DEB_*_GNU_TYPE</tt>)
2038 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2039 <tt>DEB_*_GNU_TYPE</tt>)
2041 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2042 the build machine or <tt>HOST</tt> for specification of the
2047 Backward compatibility can be provided in the rules file
2048 by setting the needed variables to suitable default
2049 values; please refer to the documentation of
2050 <prgn>dpkg-architecture</prgn> for details.
2054 It is important to understand that the <tt>DEB_*_ARCH</tt>
2055 string only determines which Debian architecture we are
2056 building on or for. It should not be used to get the CPU
2057 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2058 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2059 GNU style variables should generally only be used with upstream
2063 <sect1 id="debianrules-options">
2064 <heading><file>debian/rules</file> and
2065 <tt>DEB_BUILD_OPTIONS</tt></heading>
2068 Supporting the standardized environment variable
2069 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2070 contain several flags to change how a package is compiled and
2071 built. Each flag must be in the form <var>flag</var> or
2072 <var>flag</var>=<var>options</var>. If multiple flags are
2073 given, they must be separated by whitespace.<footnote>
2074 Some packages support any delimiter, but whitespace is the
2075 easiest to parse inside a makefile and avoids ambiguity with
2076 flag values that contain commas.
2078 <var>flag</var> must start with a lowercase letter
2079 (<tt>a-z</tt>) and consist only of lowercase letters,
2080 numbers (<tt>0-9</tt>), and the characters
2081 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2082 <var>options</var> must not contain whitespace. The same
2083 tag should not be given multiple times with conflicting
2084 values. Package maintainers may assume that
2085 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2089 The meaning of the following tags has been standardized:
2093 This tag says to not run any build-time test suite
2094 provided by the package.
2098 The presence of this tag means that the package should
2099 be compiled with a minimum of optimization. For C
2100 programs, it is best to add <tt>-O0</tt> to
2101 <tt>CFLAGS</tt> (although this is usually the default).
2102 Some programs might fail to build or run at this level
2103 of optimization; it may be necessary to use
2104 <tt>-O1</tt>, for example.
2108 This tag means that the debugging symbols should not be
2109 stripped from the binary during installation, so that
2110 debugging information may be included in the package.
2112 <tag>parallel=n</tag>
2114 This tag means that the package should be built using up
2115 to <tt>n</tt> parallel processes if the package build
2116 system supports this.<footnote>
2117 Packages built with <tt>make</tt> can often implement
2118 this by passing the <tt>-j</tt><var>n</var> option to
2121 If the package build system does not support parallel
2122 builds, this string must be ignored. If the package
2123 build system only supports a lower level of concurrency
2124 than <var>n</var>, the package should be built using as
2125 many parallel processes as the package build system
2126 supports. It is up to the package maintainer to decide
2127 whether the package build times are long enough and the
2128 package build system is robust enough to make supporting
2129 parallel builds worthwhile.
2135 Unknown flags must be ignored by <file>debian/rules</file>.
2139 The following makefile snippet is an example of how one may
2140 implement the build options; you will probably have to
2141 massage this example in order to make it work for your
2143 <example compact="compact">
2146 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2147 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2148 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2149 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2151 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2156 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2157 INSTALL_PROGRAM += -s
2159 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2160 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2161 MAKEFLAGS += -j$(NUMJOBS)
2166 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2167 # Code to run the package test suite.
2174 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2175 <sect id="substvars">
2176 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2179 When <prgn>dpkg-gencontrol</prgn>,
2180 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2181 generate control files they perform variable substitutions
2182 on their output just before writing it. Variable
2183 substitutions have the form <tt>${<var>variable</var>}</tt>.
2184 The optional file <file>debian/substvars</file> contains
2185 variable substitutions to be used; variables can also be set
2186 directly from <file>debian/rules</file> using the <tt>-V</tt>
2187 option to the source packaging commands, and certain
2188 predefined variables are also available.
2192 The <file>debian/substvars</file> file is usually generated and
2193 modified dynamically by <file>debian/rules</file> targets, in
2194 which case it must be removed by the <tt>clean</tt> target.
2198 See <manref name="deb-substvars" section="5"> for full
2199 details about source variable substitutions, including the
2200 format of <file>debian/substvars</file>.</p>
2203 <sect id="debianwatch">
2204 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2207 This is an optional, recommended control file for the
2208 <tt>uscan</tt> utility which defines how to automatically
2209 scan ftp or http sites for newly available updates of the
2210 package. This is used by <url id="
2211 http://dehs.alioth.debian.org/"> and other Debian QA tools
2212 to help with quality control and maintenance of the
2213 distribution as a whole.
2218 <sect id="debianfiles">
2219 <heading>Generated files list: <file>debian/files</file></heading>
2222 This file is not a permanent part of the source tree; it
2223 is used while building packages to record which files are
2224 being generated. <prgn>dpkg-genchanges</prgn> uses it
2225 when it generates a <file>.changes</file> file.
2229 It should not exist in a shipped source package, and so it
2230 (and any backup files or temporary files such as
2231 <file>files.new</file><footnote>
2232 <file>files.new</file> is used as a temporary file by
2233 <prgn>dpkg-gencontrol</prgn> and
2234 <prgn>dpkg-distaddfile</prgn> - they write a new
2235 version of <tt>files</tt> here before renaming it,
2236 to avoid leaving a corrupted copy if an error
2238 </footnote>) should be removed by the
2239 <tt>clean</tt> target. It may also be wise to
2240 ensure a fresh start by emptying or removing it at the
2241 start of the <tt>binary</tt> target.
2245 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2246 package, it adds an entry to <file>debian/files</file> for the
2247 <file>.deb</file> file that will be created when <tt>dpkg-deb
2248 --build</tt> is run for that binary package. So for most
2249 packages all that needs to be done with this file is to
2250 delete it in the <tt>clean</tt> target.
2254 If a package upload includes files besides the source
2255 package and any binary packages whose control files were
2256 made with <prgn>dpkg-gencontrol</prgn> then they should be
2257 placed in the parent of the package's top-level directory
2258 and <prgn>dpkg-distaddfile</prgn> should be called to add
2259 the file to the list in <file>debian/files</file>.</p>
2262 <sect id="embeddedfiles">
2263 <heading>Convenience copies of code</heading>
2266 Some software packages include in their distribution convenience
2267 copies of code from other software packages, generally so that
2268 users compiling from source don't have to download multiple
2269 packages. Debian packages should not make use of these
2270 convenience copies unless the included package is explicitly
2271 intended to be used in this way.<footnote>
2272 For example, parts of the GNU build system work like this.
2274 If the included code is already in the Debian archive in the
2275 form of a library, the Debian packaging should ensure that
2276 binary packages reference the libraries already in Debian and
2277 the convenience copy is not used. If the included code is not
2278 already in Debian, it should be packaged separately as a
2279 prerequisite if possible.
2281 Having multiple copies of the same code in Debian is
2282 inefficient, often creates either static linking or shared
2283 library conflicts, and, most importantly, increases the
2284 difficulty of handling security vulnerabilities in the
2290 <sect id="readmesource">
2291 <heading>Source package handling:
2292 <file>debian/README.source</file></heading>
2295 If running <prgn>dpkg-source -x</prgn> on a source package
2296 doesn't produce the source of the package, ready for editing,
2297 and allow one to make changes and run
2298 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2299 without taking any additional steps, creating a
2300 <file>debian/README.source</file> documentation file is
2301 recommended. This file should explain how to do all of the
2304 <item>Generate the fully patched source, in a form ready for
2305 editing, that would be built to create Debian
2306 packages. Doing this with a <tt>patch</tt> target in
2307 <file>debian/rules</file> is recommended; see
2308 <ref id="debianrules">.</item>
2309 <item>Modify the source and save those modifications so that
2310 they will be applied when building the package.</item>
2311 <item>Remove source modifications that are currently being
2312 applied when building the package.</item>
2313 <item>Optionally, document what steps are necessary to
2314 upgrade the Debian source package to a new upstream version,
2315 if applicable.</item>
2317 This explanation should include specific commands and mention
2318 any additional required Debian packages. It should not assume
2319 familiarity with any specific Debian packaging system or patch
2324 This explanation may refer to a documentation file installed by
2325 one of the package's build dependencies provided that the
2326 referenced documentation clearly explains these tasks and is not
2327 a general reference manual.
2331 <file>debian/README.source</file> may also include any other
2332 information that would be helpful to someone modifying the
2333 source package. Even if the package doesn't fit the above
2334 description, maintainers are encouraged to document in a
2335 <file>debian/README.source</file> file any source package with a
2336 particularly complex or unintuitive source layout or build
2337 system (for example, a package that builds the same source
2338 multiple times to generate different binary packages).
2344 <chapt id="controlfields">
2345 <heading>Control files and their fields</heading>
2348 The package management system manipulates data represented in
2349 a common format, known as <em>control data</em>, stored in
2350 <em>control files</em>.
2351 Control files are used for source packages, binary packages and
2352 the <file>.changes</file> files which control the installation
2353 of uploaded files<footnote>
2354 <prgn>dpkg</prgn>'s internal databases are in a similar
2359 <sect id="controlsyntax">
2360 <heading>Syntax of control files</heading>
2363 A control file consists of one or more paragraphs of
2365 The paragraphs are also sometimes referred to as stanzas.
2367 The paragraphs are separated by blank lines. Some control
2368 files allow only one paragraph; others allow several, in
2369 which case each paragraph usually refers to a different
2370 package. (For example, in source packages, the first
2371 paragraph refers to the source package, and later paragraphs
2372 refer to binary packages generated from the source.)
2376 Each paragraph consists of a series of data fields; each
2377 field consists of the field name, followed by a colon and
2378 then the data/value associated with that field. It ends at
2379 the end of the (logical) line. Horizontal whitespace
2380 (spaces and tabs) may occur immediately before or after the
2381 value and is ignored there; it is conventional to put a
2382 single space after the colon. For example, a field might
2384 <example compact="compact">
2387 the field name is <tt>Package</tt> and the field value
2392 Many fields' values may span several lines; in this case
2393 each continuation line must start with a space or a tab.
2394 Any trailing spaces or tabs at the end of individual
2395 lines of a field value are ignored.
2399 In fields where it is specified that lines may not wrap,
2400 only a single line of data is allowed and whitespace is not
2401 significant in a field body. Whitespace must not appear
2402 inside names (of packages, architectures, files or anything
2403 else) or version numbers, or between the characters of
2404 multi-character version relationships.
2408 Field names are not case-sensitive, but it is usual to
2409 capitalize the field names using mixed case as shown below.
2410 Field values are case-sensitive unless the description of the
2411 field says otherwise.
2415 Blank lines, or lines consisting only of spaces and tabs,
2416 are not allowed within field values or between fields - that
2417 would mean a new paragraph.
2421 All control files must be encoded in UTF-8.
2425 <sect id="sourcecontrolfiles">
2426 <heading>Source package control files -- <file>debian/control</file></heading>
2429 The <file>debian/control</file> file contains the most vital
2430 (and version-independent) information about the source package
2431 and about the binary packages it creates.
2435 The first paragraph of the control file contains information about
2436 the source package in general. The subsequent sets each describe a
2437 binary package that the source tree builds.
2441 The fields in the general paragraph (the first one, for the source
2444 <list compact="compact">
2445 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2446 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2447 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2448 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2449 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2450 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2451 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2452 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2457 The fields in the binary package paragraphs are:
2459 <list compact="compact">
2460 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2461 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2462 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2463 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2464 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2465 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2466 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2467 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2472 The syntax and semantics of the fields are described below.
2478 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2479 generate control files for binary packages (see below), by
2480 <prgn>dpkg-genchanges</prgn> to generate the
2481 <tt>.changes</tt> file to accompany the upload, and by
2482 <prgn>dpkg-source</prgn> when it creates the
2483 <file>.dsc</file> source control file as part of a source
2484 archive. Many fields are permitted to span multiple lines in
2485 <file>debian/control</file> but not in any other control
2486 file. These tools are responsible for removing the line
2487 breaks from such fields when using fields from
2488 <file>debian/control</file> to generate other control files.
2492 The fields here may contain variable references - their
2493 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2494 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2495 when they generate output control files.
2496 See <ref id="substvars"> for details.
2500 In addition to the control file syntax described <qref
2501 id="controlsyntax">above</qref>, this file may also contain
2502 comment lines starting with <tt>#</tt> without any preceding
2503 whitespace. All such lines are ignored, even in the middle of
2504 continuation lines for a multiline field, and do not end a
2510 <sect id="binarycontrolfiles">
2511 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2514 The <file>DEBIAN/control</file> file contains the most vital
2515 (and version-dependent) information about a binary package.
2519 The fields in this file are:
2521 <list compact="compact">
2522 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2523 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2524 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2525 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2526 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2527 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2528 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2529 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2530 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2531 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2532 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2533 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2538 <sect id="debiansourcecontrolfiles">
2539 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2542 This file contains a series of fields, identified and
2543 separated just like the fields in the control file of
2544 a binary package. The fields are listed below; their
2545 syntax is described above, in <ref id="pkg-controlfields">.
2547 <list compact="compact">
2548 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2549 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2550 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2551 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2552 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2553 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2554 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2555 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2556 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2557 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2558 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2563 The source package control file is generated by
2564 <prgn>dpkg-source</prgn> when it builds the source
2565 archive, from other files in the source package,
2566 described above. When unpacking, it is checked against
2567 the files and directories in the other parts of the
2573 <sect id="debianchangesfiles">
2574 <heading>Debian changes files -- <file>.changes</file></heading>
2577 The .changes files are used by the Debian archive maintenance
2578 software to process updates to packages. They contain one
2579 paragraph which contains information from the
2580 <tt>debian/control</tt> file and other data about the
2581 source package gathered via <tt>debian/changelog</tt>
2582 and <tt>debian/rules</tt>.
2586 The fields in this file are:
2588 <list compact="compact">
2589 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2590 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2591 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2592 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2593 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2594 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2595 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2596 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2597 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2598 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2599 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2600 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2601 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2602 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2607 <sect id="controlfieldslist">
2608 <heading>List of fields</heading>
2610 <sect1 id="f-Source">
2611 <heading><tt>Source</tt></heading>
2614 This field identifies the source package name.
2618 In <file>debian/control</file> or a <file>.dsc</file> file,
2619 this field must contain only the name of the source package.
2623 In a binary package control file or a <file>.changes</file>
2624 file, the source package name may be followed by a version
2625 number in parentheses<footnote>
2626 It is customary to leave a space after the package name
2627 if a version number is specified.
2629 This version number may be omitted (and is, by
2630 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2631 the <tt>Version</tt> field of the binary package in
2632 question. The field itself may be omitted from a binary
2633 package control file when the source package has the same
2634 name and version as the binary package.
2638 Package names (both source and binary,
2639 see <ref id="f-Package">) must consist only of lower case
2640 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2641 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2642 (<tt>.</tt>). They must be at least two characters long and
2643 must start with an alphanumeric character.
2647 <sect1 id="f-Maintainer">
2648 <heading><tt>Maintainer</tt></heading>
2651 The package maintainer's name and email address. The name
2652 should come first, then the email address inside angle
2653 brackets <tt><></tt> (in RFC822 format).
2657 If the maintainer's name contains a full stop then the
2658 whole field will not work directly as an email address due
2659 to a misfeature in the syntax specified in RFC822; a
2660 program using this field as an address must check for this
2661 and correct the problem if necessary (for example by
2662 putting the name in round brackets and moving it to the
2663 end, and bringing the email address forward).
2667 <sect1 id="f-Uploaders">
2668 <heading><tt>Uploaders</tt></heading>
2671 List of the names and email addresses of co-maintainers of
2672 the package, if any. If the package has other maintainers
2673 beside the one named in the
2674 <qref id="f-Maintainer">Maintainer field</qref>, their
2675 names and email addresses should be listed here. The
2676 format is the same as that of the Maintainer tag, and
2677 multiple entries should be comma separated. Currently,
2678 this field is restricted to a single line of data. This
2679 is an optional field.
2682 Any parser that interprets the Uploaders field in
2683 <file>debian/control</file> must permit it to span multiple
2684 lines. Line breaks in an Uploaders field that spans multiple
2685 lines are not significant and the semantics of the field are
2686 the same as if the line breaks had not been present.
2690 <sect1 id="f-Changed-By">
2691 <heading><tt>Changed-By</tt></heading>
2694 The name and email address of the person who changed the
2695 said package. Usually the name of the maintainer.
2696 All the rules for the Maintainer field apply here, too.
2700 <sect1 id="f-Section">
2701 <heading><tt>Section</tt></heading>
2704 This field specifies an application area into which the package
2705 has been classified. See <ref id="subsections">.
2709 When it appears in the <file>debian/control</file> file,
2710 it gives the value for the subfield of the same name in
2711 the <tt>Files</tt> field of the <file>.changes</file> file.
2712 It also gives the default for the same field in the binary
2717 <sect1 id="f-Priority">
2718 <heading><tt>Priority</tt></heading>
2721 This field represents how important it is that the user
2722 have the package installed. See <ref id="priorities">.
2726 When it appears in the <file>debian/control</file> file,
2727 it gives the value for the subfield of the same name in
2728 the <tt>Files</tt> field of the <file>.changes</file> file.
2729 It also gives the default for the same field in the binary
2734 <sect1 id="f-Package">
2735 <heading><tt>Package</tt></heading>
2738 The name of the binary package.
2742 Binary package names must follow the same syntax and
2743 restrictions as source package names. See <ref id="f-Source">
2748 <sect1 id="f-Architecture">
2749 <heading><tt>Architecture</tt></heading>
2752 Depending on context and the control file used, the
2753 <tt>Architecture</tt> field can include the following sets of
2757 A unique single word identifying a Debian machine
2758 architecture as described in <ref id="arch-spec">.
2761 An architecture wildcard identifying a set of Debian
2762 machine architectures, see <ref id="arch-wildcard-spec">.
2763 <tt>any</tt> matches all Debian machine architectures
2764 and is the most frequently used.
2767 <tt>all</tt>, which indicates an
2768 architecture-independent package.
2771 <tt>source</tt>, which indicates a source package.
2777 In the main <file>debian/control</file> file in the source
2778 package, this field may contain the special
2779 value <tt>all</tt>, the special architecture
2780 wildcard <tt>any</tt>, or a list of specific and wildcard
2781 architectures separated by spaces. If <tt>all</tt>
2782 or <tt>any</tt> appears, that value must be the entire
2783 contents of the field. Most packages will use
2784 either <tt>all</tt> or <tt>any</tt>.
2788 Specifying a specific list of architectures indicates that the
2789 source will build an architecture-dependent package only on
2790 architectures included in the list. Specifying a list of
2791 architecture wildcards indicates that the source will build an
2792 architecture-dependent package on only those architectures
2793 that match any of the specified architecture wildcards.
2794 Specifying a list of architectures or architecture wildcards
2795 other than <tt>any</tt> is for the minority of cases where a
2796 program is not portable or is not useful on some
2797 architectures. Where possible, the program should be made
2802 In the source package control file <file>.dsc</file>, this
2803 field may contain either the architecture
2804 wildcard <tt>any</tt> or a list of architectures and
2805 architecture wildcards separated by spaces. If a list is
2806 given, it may include (or consist solely of) the special
2807 value <tt>all</tt>. In other words, in <file>.dsc</file>
2808 files unlike the <file>debian/control</file>, <tt>all</tt> may
2809 occur in combination with specific architectures.
2810 The <tt>Architecture</tt> field in the source package control
2811 file <file>.dsc</file> is generally constructed from
2812 the <tt>Architecture</tt> fields in
2813 the <file>debian/control</file> in the source package.
2817 Specifying <tt>any</tt> indicates that the source package
2818 isn't dependent on any particular architecture and should
2819 compile fine on any one. The produced binary package(s)
2820 will either be specific to whatever the current build
2821 architecture is or will be architecture-independent.
2825 Specifying only <tt>all</tt> indicates that the source package
2826 will only build architecture-independent packages. If this is
2827 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2828 <tt>any</tt> implies that the source package will build at
2829 least one architecture-dependent package.
2833 Specifying a list of architectures or architecture wildcards
2834 indicates that the source will build an architecture-dependent
2835 package, and will only work correctly on the listed or
2836 matching architectures. If the source package also builds at
2837 least one architecture-independent package, <tt>all</tt> will
2838 also be included in the list.
2842 In a <file>.changes</file> file, the <tt>Architecture</tt>
2843 field lists the architecture(s) of the package(s) currently
2844 being uploaded. This will be a list; if the source for the
2845 package is also being uploaded, the special
2846 entry <tt>source</tt> is also present. <tt>all</tt> will be
2847 present if any architecture-independent packages are being
2848 uploaded. Architecture wildcards such as <tt>any</tt> must
2849 never occur in the <tt>Architecture</tt> field in
2850 the <file>.changes</file> file.
2854 See <ref id="debianrules"> for information on how to get
2855 the architecture for the build process.
2859 <sect1 id="f-Essential">
2860 <heading><tt>Essential</tt></heading>
2863 This is a boolean field which may occur only in the
2864 control file of a binary package or in a per-package fields
2865 paragraph of a main source control data file.
2869 If set to <tt>yes</tt> then the package management system
2870 will refuse to remove the package (upgrading and replacing
2871 it is still possible). The other possible value is <tt>no</tt>,
2872 which is the same as not having the field at all.
2877 <heading>Package interrelationship fields:
2878 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2879 <tt>Recommends</tt>, <tt>Suggests</tt>,
2880 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2881 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2885 These fields describe the package's relationships with
2886 other packages. Their syntax and semantics are described
2887 in <ref id="relationships">.</p>
2890 <sect1 id="f-Standards-Version">
2891 <heading><tt>Standards-Version</tt></heading>
2894 The most recent version of the standards (the policy
2895 manual and associated texts) with which the package
2900 The version number has four components: major and minor
2901 version number and major and minor patch level. When the
2902 standards change in a way that requires every package to
2903 change the major number will be changed. Significant
2904 changes that will require work in many packages will be
2905 signaled by a change to the minor number. The major patch
2906 level will be changed for any change to the meaning of the
2907 standards, however small; the minor patch level will be
2908 changed when only cosmetic, typographical or other edits
2909 are made which neither change the meaning of the document
2910 nor affect the contents of packages.
2914 Thus only the first three components of the policy version
2915 are significant in the <em>Standards-Version</em> control
2916 field, and so either these three components or all four
2917 components may be specified.<footnote>
2918 In the past, people specified the full version number
2919 in the Standards-Version field, for example "2.3.0.0".
2920 Since minor patch-level changes don't introduce new
2921 policy, it was thought it would be better to relax
2922 policy and only require the first 3 components to be
2923 specified, in this example "2.3.0". All four
2924 components may still be used if someone wishes to do so.
2930 <sect1 id="f-Version">
2931 <heading><tt>Version</tt></heading>
2934 The version number of a package. The format is:
2935 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2939 The three components here are:
2941 <tag><var>epoch</var></tag>
2944 This is a single (generally small) unsigned integer. It
2945 may be omitted, in which case zero is assumed. If it is
2946 omitted then the <var>upstream_version</var> may not
2951 It is provided to allow mistakes in the version numbers
2952 of older versions of a package, and also a package's
2953 previous version numbering schemes, to be left behind.
2957 <tag><var>upstream_version</var></tag>
2960 This is the main part of the version number. It is
2961 usually the version number of the original ("upstream")
2962 package from which the <file>.deb</file> file has been made,
2963 if this is applicable. Usually this will be in the same
2964 format as that specified by the upstream author(s);
2965 however, it may need to be reformatted to fit into the
2966 package management system's format and comparison
2971 The comparison behavior of the package management system
2972 with respect to the <var>upstream_version</var> is
2973 described below. The <var>upstream_version</var>
2974 portion of the version number is mandatory.
2978 The <var>upstream_version</var> may contain only
2979 alphanumerics<footnote>
2980 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2982 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2983 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2984 tilde) and should start with a digit. If there is no
2985 <var>debian_revision</var> then hyphens are not allowed;
2986 if there is no <var>epoch</var> then colons are not
2991 <tag><var>debian_revision</var></tag>
2994 This part of the version number specifies the version of
2995 the Debian package based on the upstream version. It
2996 may contain only alphanumerics and the characters
2997 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
2998 tilde) and is compared in the same way as the
2999 <var>upstream_version</var> is.
3003 It is optional; if it isn't present then the
3004 <var>upstream_version</var> may not contain a hyphen.
3005 This format represents the case where a piece of
3006 software was written specifically to be turned into a
3007 Debian package, and so there is only one "debianisation"
3008 of it and therefore no revision indication is required.
3012 It is conventional to restart the
3013 <var>debian_revision</var> at <tt>1</tt> each time the
3014 <var>upstream_version</var> is increased.
3018 The package management system will break the version
3019 number apart at the last hyphen in the string (if there
3020 is one) to determine the <var>upstream_version</var> and
3021 <var>debian_revision</var>. The absence of a
3022 <var>debian_revision</var> is equivalent to a
3023 <var>debian_revision</var> of <tt>0</tt>.
3030 When comparing two version numbers, first the <var>epoch</var>
3031 of each are compared, then the <var>upstream_version</var> if
3032 <var>epoch</var> is equal, and then <var>debian_revision</var>
3033 if <var>upstream_version</var> is also equal.
3034 <var>epoch</var> is compared numerically. The
3035 <var>upstream_version</var> and <var>debian_revision</var>
3036 parts are compared by the package management system using the
3037 following algorithm:
3041 The strings are compared from left to right.
3045 First the initial part of each string consisting entirely of
3046 non-digit characters is determined. These two parts (one of
3047 which may be empty) are compared lexically. If a difference
3048 is found it is returned. The lexical comparison is a
3049 comparison of ASCII values modified so that all the letters
3050 sort earlier than all the non-letters and so that a tilde
3051 sorts before anything, even the end of a part. For example,
3052 the following parts are in sorted order from earliest to
3053 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3054 <tt>a</tt>.<footnote>
3055 One common use of <tt>~</tt> is for upstream pre-releases.
3056 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3057 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3062 Then the initial part of the remainder of each string which
3063 consists entirely of digit characters is determined. The
3064 numerical values of these two parts are compared, and any
3065 difference found is returned as the result of the comparison.
3066 For these purposes an empty string (which can only occur at
3067 the end of one or both version strings being compared) counts
3072 These two steps (comparing and removing initial non-digit
3073 strings and initial digit strings) are repeated until a
3074 difference is found or both strings are exhausted.
3078 Note that the purpose of epochs is to allow us to leave behind
3079 mistakes in version numbering, and to cope with situations
3080 where the version numbering scheme changes. It is
3081 <em>not</em> intended to cope with version numbers containing
3082 strings of letters which the package management system cannot
3083 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3084 silly orderings.<footnote>
3085 The author of this manual has heard of a package whose
3086 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3087 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3093 <sect1 id="f-Description">
3094 <heading><tt>Description</tt></heading>
3097 In a source or binary control file, the <tt>Description</tt>
3098 field contains a description of the binary package, consisting
3099 of two parts, the synopsis or the short description, and the
3100 long description. The field's format is as follows:
3105 Description: <single line synopsis>
3106 <extended description over several lines>
3111 The lines in the extended description can have these formats:
3117 Those starting with a single space are part of a paragraph.
3118 Successive lines of this form will be word-wrapped when
3119 displayed. The leading space will usually be stripped off.
3123 Those starting with two or more spaces. These will be
3124 displayed verbatim. If the display cannot be panned
3125 horizontally, the displaying program will line wrap them "hard"
3126 (i.e., without taking account of word breaks). If it can they
3127 will be allowed to trail off to the right. None, one or two
3128 initial spaces may be deleted, but the number of spaces
3129 deleted from each line will be the same (so that you can have
3130 indenting work correctly, for example).
3134 Those containing a single space followed by a single full stop
3135 character. These are rendered as blank lines. This is the
3136 <em>only</em> way to get a blank line<footnote>
3137 Completely empty lines will not be rendered as blank lines.
3138 Instead, they will cause the parser to think you're starting
3139 a whole new record in the control file, and will therefore
3140 likely abort with an error.
3145 Those containing a space, a full stop and some more characters.
3146 These are for future expansion. Do not use them.
3152 Do not use tab characters. Their effect is not predictable.
3156 See <ref id="descriptions"> for further information on this.
3160 In a <file>.changes</file> file, the <tt>Description</tt>
3161 field contains a summary of the descriptions for the packages
3162 being uploaded. For this case, the first line of the field
3163 value (the part on the same line as <tt>Description:</tt>) is
3164 always empty. The content of the field is expressed as
3165 continuation lines, one line per package. Each line is
3166 indented by one space and contains the name of a binary
3167 package, a space, a hyphen (<tt>-</tt>), a space, and the
3168 short description line from that package.
3172 <sect1 id="f-Distribution">
3173 <heading><tt>Distribution</tt></heading>
3176 In a <file>.changes</file> file or parsed changelog output
3177 this contains the (space-separated) name(s) of the
3178 distribution(s) where this version of the package should
3179 be installed. Valid distributions are determined by the
3180 archive maintainers.<footnote>
3181 Example distribution names in the Debian archive used in
3182 <file>.changes</file> files are:
3183 <taglist compact="compact">
3184 <tag><em>unstable</em></tag>
3186 This distribution value refers to the
3187 <em>developmental</em> part of the Debian distribution
3188 tree. Most new packages, new upstream versions of
3189 packages and bug fixes go into the <em>unstable</em>
3193 <tag><em>experimental</em></tag>
3195 The packages with this distribution value are deemed
3196 by their maintainers to be high risk. Oftentimes they
3197 represent early beta or developmental packages from
3198 various sources that the maintainers want people to
3199 try, but are not ready to be a part of the other parts
3200 of the Debian distribution tree.
3205 Others are used for updating stable releases or for
3206 security uploads. More information is available in the
3207 Debian Developer's Reference, section "The Debian
3211 The Debian archive software only supports listing a single
3212 distribution. Migration of packages to other distributions is
3213 handled outside of the upload process.
3218 <heading><tt>Date</tt></heading>
3221 This field includes the date the package was built or last edited.
3225 The value of this field is usually extracted from the
3226 <file>debian/changelog</file> file - see
3227 <ref id="dpkgchangelog">).
3231 <sect1 id="f-Format">
3232 <heading><tt>Format</tt></heading>
3235 This field specifies a format revision for the file.
3236 The most current format described in the Policy Manual
3237 is version <strong>1.5</strong>. The syntax of the
3238 format value is the same as that of a package version
3239 number except that no epoch or Debian revision is allowed
3240 - see <ref id="f-Version">.
3244 <sect1 id="f-Urgency">
3245 <heading><tt>Urgency</tt></heading>
3248 This is a description of how important it is to upgrade to
3249 this version from previous ones. It consists of a single
3250 keyword taking one of the values <tt>low</tt>,
3251 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3252 <tt>critical</tt><footnote>
3253 Other urgency values are supported with configuration
3254 changes in the archive software but are not used in Debian.
3255 The urgency affects how quickly a package will be considered
3256 for inclusion into the <tt>testing</tt> distribution and
3257 gives an indication of the importance of any fixes included
3258 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3259 treated as synonymous.
3260 </footnote> (not case-sensitive) followed by an optional
3261 commentary (separated by a space) which is usually in
3262 parentheses. For example:
3265 Urgency: low (HIGH for users of diversions)
3271 The value of this field is usually extracted from the
3272 <file>debian/changelog</file> file - see
3273 <ref id="dpkgchangelog">.
3277 <sect1 id="f-Changes">
3278 <heading><tt>Changes</tt></heading>
3281 This field contains the human-readable changes data, describing
3282 the differences between the last version and the current one.
3286 The first line of the field value (the part on the same line
3287 as <tt>Changes:</tt>) is always empty. The content of the
3288 field is expressed as continuation lines, with each line
3289 indented by at least one space. Blank lines must be
3290 represented by a line consisting only of a space and a full
3295 The value of this field is usually extracted from the
3296 <file>debian/changelog</file> file - see
3297 <ref id="dpkgchangelog">).
3301 Each version's change information should be preceded by a
3302 "title" line giving at least the version, distribution(s)
3303 and urgency, in a human-readable way.
3307 If data from several versions is being returned the entry
3308 for the most recent version should be returned first, and
3309 entries should be separated by the representation of a
3310 blank line (the "title" line may also be followed by the
3311 representation of a blank line).
3315 <sect1 id="f-Binary">
3316 <heading><tt>Binary</tt></heading>
3319 This field is a list of binary packages. Its syntax and
3320 meaning varies depending on the control file in which it
3325 When it appears in the <file>.dsc</file> file, it lists binary
3326 packages which a source package can produce, separated by
3328 A space after each comma is conventional.
3329 </footnote>. It may span multiple lines. The source package
3330 does not necessarily produce all of these binary packages for
3331 every architecture. The source control file doesn't contain
3332 details of which architectures are appropriate for which of
3333 the binary packages.
3337 When it appears in a <file>.changes</file> file, it lists the
3338 names of the binary packages being uploaded, separated by
3339 whitespace (not commas). It may span multiple lines.
3343 <sect1 id="f-Installed-Size">
3344 <heading><tt>Installed-Size</tt></heading>
3347 This field appears in the control files of binary packages,
3348 and in the <file>Packages</file> files. It gives an estimate
3349 of the total amount of disk space required to install the
3350 named package. Actual installed size may vary based on block
3351 size, file system properties, or actions taken by package
3356 The disk space is given as the integer value of the estimated
3357 installed size in bytes, divided by 1024 and rounded up.
3361 <sect1 id="f-Files">
3362 <heading><tt>Files</tt></heading>
3365 This field contains a list of files with information about
3366 each one. The exact information and syntax varies with
3371 In all cases, Files is a multiline field. The first line of
3372 the field value (the part on the same line as <tt>Files:</tt>)
3373 is always empty. The content of the field is expressed as
3374 continuation lines, one line per file. Each line must be
3375 indented by one space and contain a number of sub-fields,
3376 separated by spaces, as described below.
3380 In the <file>.dsc</file> file, each line contains the MD5
3381 checksum, size and filename of the tar file and (if
3382 applicable) diff file which make up the remainder of the
3383 source package<footnote>
3384 That is, the parts which are not the <tt>.dsc</tt>.
3385 </footnote>. For example:
3388 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3389 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3391 The exact forms of the filenames are described
3392 in <ref id="pkg-sourcearchives">.
3396 In the <file>.changes</file> file this contains one line per
3397 file being uploaded. Each line contains the MD5 checksum,
3398 size, section and priority and the filename. For example:
3401 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3402 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3403 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3404 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3406 The <qref id="f-Section">section</qref>
3407 and <qref id="f-Priority">priority</qref> are the values of
3408 the corresponding fields in the main source control file. If
3409 no section or priority is specified then <tt>-</tt> should be
3410 used, though section and priority values must be specified for
3411 new packages to be installed properly.
3415 The special value <tt>byhand</tt> for the section in a
3416 <tt>.changes</tt> file indicates that the file in question
3417 is not an ordinary package file and must by installed by
3418 hand by the distribution maintainers. If the section is
3419 <tt>byhand</tt> the priority should be <tt>-</tt>.
3423 If a new Debian revision of a package is being shipped and
3424 no new original source archive is being distributed the
3425 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3426 entry for the original source archive
3427 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3428 but the <file>.changes</file> file should leave it out. In
3429 this case the original source archive on the distribution
3430 site must match exactly, byte-for-byte, the original
3431 source archive which was used to generate the
3432 <file>.dsc</file> file and diff which are being uploaded.</p>
3435 <sect1 id="f-Closes">
3436 <heading><tt>Closes</tt></heading>
3439 A space-separated list of bug report numbers that the upload
3440 governed by the .changes file closes.
3444 <sect1 id="f-Homepage">
3445 <heading><tt>Homepage</tt></heading>
3448 The URL of the web site for this package, preferably (when
3449 applicable) the site from which the original source can be
3450 obtained and any additional upstream documentation or
3451 information may be found. The content of this field is a
3452 simple URL without any surrounding characters such as
3460 <heading>User-defined fields</heading>
3463 Additional user-defined fields may be added to the
3464 source package control file. Such fields will be
3465 ignored, and not copied to (for example) binary or
3466 source package control files or upload control files.
3470 If you wish to add additional unsupported fields to
3471 these output files you should use the mechanism
3476 Fields in the main source control information file with
3477 names starting <tt>X</tt>, followed by one or more of
3478 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3479 be copied to the output files. Only the part of the
3480 field name after the hyphen will be used in the output
3481 file. Where the letter <tt>B</tt> is used the field
3482 will appear in binary package control files, where the
3483 letter <tt>S</tt> is used in source package control
3484 files and where <tt>C</tt> is used in upload control
3485 (<tt>.changes</tt>) files.
3489 For example, if the main source information control file
3492 XBS-Comment: I stand between the candle and the star.
3494 then the binary and source package control files will contain the
3497 Comment: I stand between the candle and the star.
3506 <chapt id="maintainerscripts">
3507 <heading>Package maintainer scripts and installation procedure</heading>
3510 <heading>Introduction to package maintainer scripts</heading>
3513 It is possible to supply scripts as part of a package which
3514 the package management system will run for you when your
3515 package is installed, upgraded or removed.
3519 These scripts are the files <prgn>preinst</prgn>,
3520 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3521 <prgn>postrm</prgn> in the control area of the package.
3522 They must be proper executable files; if they are scripts
3523 (which is recommended), they must start with the usual
3524 <tt>#!</tt> convention. They should be readable and
3525 executable by anyone, and must not be world-writable.
3529 The package management system looks at the exit status from
3530 these scripts. It is important that they exit with a
3531 non-zero status if there is an error, so that the package
3532 management system can stop its processing. For shell
3533 scripts this means that you <em>almost always</em> need to
3534 use <tt>set -e</tt> (this is usually true when writing shell
3535 scripts, in fact). It is also important, of course, that
3536 they exit with a zero status if everything went well.
3540 Additionally, packages interacting with users using
3541 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3542 install a <prgn>config</prgn> script in the control area,
3543 see <ref id="maintscriptprompt"> for details.
3547 When a package is upgraded a combination of the scripts from
3548 the old and new packages is called during the upgrade
3549 procedure. If your scripts are going to be at all
3550 complicated you need to be aware of this, and may need to
3551 check the arguments to your scripts.
3555 Broadly speaking the <prgn>preinst</prgn> is called before
3556 (a particular version of) a package is installed, and the
3557 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3558 before (a version of) a package is removed and the
3559 <prgn>postrm</prgn> afterwards.
3563 Programs called from maintainer scripts should not normally
3564 have a path prepended to them. Before installation is
3565 started, the package management system checks to see if the
3566 programs <prgn>ldconfig</prgn>,
3567 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3568 and <prgn>update-rc.d</prgn> can be found via the
3569 <tt>PATH</tt> environment variable. Those programs, and any
3570 other program that one would expect to be in the
3571 <tt>PATH</tt>, should thus be invoked without an absolute
3572 pathname. Maintainer scripts should also not reset the
3573 <tt>PATH</tt>, though they might choose to modify it by
3574 prepending or appending package-specific directories. These
3575 considerations really apply to all shell scripts.</p>
3578 <sect id="idempotency">
3579 <heading>Maintainer scripts idempotency</heading>
3582 It is necessary for the error recovery procedures that the
3583 scripts be idempotent. This means that if it is run
3584 successfully, and then it is called again, it doesn't bomb
3585 out or cause any harm, but just ensures that everything is
3586 the way it ought to be. If the first call failed, or
3587 aborted half way through for some reason, the second call
3588 should merely do the things that were left undone the first
3589 time, if any, and exit with a success status if everything
3591 This is so that if an error occurs, the user interrupts
3592 <prgn>dpkg</prgn> or some other unforeseen circumstance
3593 happens you don't leave the user with a badly-broken
3594 package when <prgn>dpkg</prgn> attempts to repeat the
3600 <sect id="controllingterminal">
3601 <heading>Controlling terminal for maintainer scripts</heading>
3604 Maintainer scripts are not guaranteed to run with a controlling
3605 terminal and may not be able to interact with the user. They
3606 must be able to fall back to noninteractive behavior if no
3607 controlling terminal is available. Maintainer scripts that
3608 prompt via a program conforming to the Debian Configuration
3609 Management Specification (see <ref id="maintscriptprompt">) may
3610 assume that program will handle falling back to noninteractive
3615 For high-priority prompts without a reasonable default answer,
3616 maintainer scripts may abort if there is no controlling
3617 terminal. However, this situation should be avoided if at all
3618 possible, since it prevents automated or unattended installs.
3619 In most cases, users will consider this to be a bug in the
3624 <sect id="exitstatus">
3625 <heading>Exit status</heading>
3628 Each script must return a zero exit status for
3629 success, or a nonzero one for failure, since the package
3630 management system looks for the exit status of these scripts
3631 and determines what action to take next based on that datum.
3635 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3640 <list compact="compact">
3642 <var>new-preinst</var> <tt>install</tt>
3645 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3648 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3651 <var>old-preinst</var> <tt>abort-upgrade</tt>
3652 <var>new-version</var>
3657 <list compact="compact">
3659 <var>postinst</var> <tt>configure</tt>
3660 <var>most-recently-configured-version</var>
3663 <var>old-postinst</var> <tt>abort-upgrade</tt>
3664 <var>new-version</var>
3667 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3668 <tt>in-favour</tt> <var>package</var>
3669 <var>new-version</var>
3672 <var>postinst</var> <tt>abort-remove</tt>
3675 <var>deconfigured's-postinst</var>
3676 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3677 <var>failed-install-package</var> <var>version</var>
3678 [<tt>removing</tt> <var>conflicting-package</var>
3684 <list compact="compact">
3686 <var>prerm</var> <tt>remove</tt>
3689 <var>old-prerm</var> <tt>upgrade</tt>
3690 <var>new-version</var>
3693 <var>new-prerm</var> <tt>failed-upgrade</tt>
3694 <var>old-version</var>
3697 <var>conflictor's-prerm</var> <tt>remove</tt>
3698 <tt>in-favour</tt> <var>package</var>
3699 <var>new-version</var>
3702 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3703 <tt>in-favour</tt> <var>package-being-installed</var>
3704 <var>version</var> [<tt>removing</tt>
3705 <var>conflicting-package</var>
3711 <list compact="compact">
3713 <var>postrm</var> <tt>remove</tt>
3716 <var>postrm</var> <tt>purge</tt>
3719 <var>old-postrm</var> <tt>upgrade</tt>
3720 <var>new-version</var>
3723 <var>new-postrm</var> <tt>failed-upgrade</tt>
3724 <var>old-version</var>
3727 <var>new-postrm</var> <tt>abort-install</tt>
3730 <var>new-postrm</var> <tt>abort-install</tt>
3731 <var>old-version</var>
3734 <var>new-postrm</var> <tt>abort-upgrade</tt>
3735 <var>old-version</var>
3738 <var>disappearer's-postrm</var> <tt>disappear</tt>
3739 <var>overwriter</var>
3740 <var>overwriter-version</var>
3746 <sect id="unpackphase">
3747 <heading>Details of unpack phase of installation or upgrade</heading>
3750 The procedure on installation/upgrade/overwrite/disappear
3751 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3752 stage of <tt>dpkg --install</tt>) is as follows. In each
3753 case, if a major error occurs (unless listed below) the
3754 actions are, in general, run backwards - this means that the
3755 maintainer scripts are run with different arguments in
3756 reverse order. These are the "error unwind" calls listed
3763 If a version of the package is already installed, call
3764 <example compact="compact">
3765 <var>old-prerm</var> upgrade <var>new-version</var>
3769 If the script runs but exits with a non-zero
3770 exit status, <prgn>dpkg</prgn> will attempt:
3771 <example compact="compact">
3772 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3774 If this works, the upgrade continues. If this
3775 does not work, the error unwind:
3776 <example compact="compact">
3777 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3779 If this works, then the old-version is
3780 "Installed", if not, the old version is in a
3781 "Half-Configured" state.
3787 If a "conflicting" package is being removed at the same time,
3788 or if any package will be broken (due to <tt>Breaks</tt>):
3791 If <tt>--auto-deconfigure</tt> is
3792 specified, call, for each package to be deconfigured
3793 due to <tt>Breaks</tt>:
3794 <example compact="compact">
3795 <var>deconfigured's-prerm</var> deconfigure \
3796 in-favour <var>package-being-installed</var> <var>version</var>
3799 <example compact="compact">
3800 <var>deconfigured's-postinst</var> abort-deconfigure \
3801 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3803 The deconfigured packages are marked as
3804 requiring configuration, so that if
3805 <tt>--install</tt> is used they will be
3806 configured again if possible.
3809 If any packages depended on a conflicting
3810 package being removed and <tt>--auto-deconfigure</tt> is
3811 specified, call, for each such package:
3812 <example compact="compact">
3813 <var>deconfigured's-prerm</var> deconfigure \
3814 in-favour <var>package-being-installed</var> <var>version</var> \
3815 removing <var>conflicting-package</var> <var>version</var>
3818 <example compact="compact">
3819 <var>deconfigured's-postinst</var> abort-deconfigure \
3820 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3821 removing <var>conflicting-package</var> <var>version</var>
3823 The deconfigured packages are marked as
3824 requiring configuration, so that if
3825 <tt>--install</tt> is used they will be
3826 configured again if possible.
3829 To prepare for removal of each conflicting package, call:
3830 <example compact="compact">
3831 <var>conflictor's-prerm</var> remove \
3832 in-favour <var>package</var> <var>new-version</var>
3835 <example compact="compact">
3836 <var>conflictor's-postinst</var> abort-remove \
3837 in-favour <var>package</var> <var>new-version</var>
3846 If the package is being upgraded, call:
3847 <example compact="compact">
3848 <var>new-preinst</var> upgrade <var>old-version</var>
3850 If this fails, we call:
3852 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3859 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3861 is called. If this works, then the old version
3862 is in an "Installed" state, or else it is left
3863 in an "Unpacked" state.
3868 If it fails, then the old version is left
3869 in an "Half-Installed" state.
3876 Otherwise, if the package had some configuration
3877 files from a previous version installed (i.e., it
3878 is in the "configuration files only" state):
3879 <example compact="compact">
3880 <var>new-preinst</var> install <var>old-version</var>
3884 <var>new-postrm</var> abort-install <var>old-version</var>
3886 If this fails, the package is left in a
3887 "Half-Installed" state, which requires a
3888 reinstall. If it works, the packages is left in
3889 a "Config-Files" state.
3892 Otherwise (i.e., the package was completely purged):
3893 <example compact="compact">
3894 <var>new-preinst</var> install
3897 <example compact="compact">
3898 <var>new-postrm</var> abort-install
3900 If the error-unwind fails, the package is in a
3901 "Half-Installed" phase, and requires a
3902 reinstall. If the error unwind works, the
3903 package is in a not installed state.
3910 The new package's files are unpacked, overwriting any
3911 that may be on the system already, for example any
3912 from the old version of the same package or from
3913 another package. Backups of the old files are kept
3914 temporarily, and if anything goes wrong the package
3915 management system will attempt to put them back as
3916 part of the error unwind.
3920 It is an error for a package to contain files which
3921 are on the system in another package, unless
3922 <tt>Replaces</tt> is used (see <ref id="replaces">).
3924 The following paragraph is not currently the case:
3925 Currently the <tt>- - force-overwrite</tt> flag is
3926 enabled, downgrading it to a warning, but this may not
3932 It is a more serious error for a package to contain a
3933 plain file or other kind of non-directory where another
3934 package has a directory (again, unless
3935 <tt>Replaces</tt> is used). This error can be
3936 overridden if desired using
3937 <tt>--force-overwrite-dir</tt>, but this is not
3942 Packages which overwrite each other's files produce
3943 behavior which, though deterministic, is hard for the
3944 system administrator to understand. It can easily
3945 lead to "missing" programs if, for example, a package
3946 is installed which overwrites a file from another
3947 package, and is then removed again.<footnote>
3948 Part of the problem is due to what is arguably a
3949 bug in <prgn>dpkg</prgn>.
3954 A directory will never be replaced by a symbolic link
3955 to a directory or vice versa; instead, the existing
3956 state (symlink or not) will be left alone and
3957 <prgn>dpkg</prgn> will follow the symlink if there is
3966 If the package is being upgraded, call
3967 <example compact="compact">
3968 <var>old-postrm</var> upgrade <var>new-version</var>
3972 If this fails, <prgn>dpkg</prgn> will attempt:
3973 <example compact="compact">
3974 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3976 If this works, installation continues. If not,
3978 <example compact="compact">
3979 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3981 If this fails, the old version is left in a
3982 "Half-Installed" state. If it works, dpkg now
3984 <example compact="compact">
3985 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3987 If this fails, the old version is left in a
3988 "Half-Installed" state. If it works, dpkg now
3990 <example compact="compact">
3991 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3993 If this fails, the old version is in an
4000 This is the point of no return - if
4001 <prgn>dpkg</prgn> gets this far, it won't back off
4002 past this point if an error occurs. This will
4003 leave the package in a fairly bad state, which
4004 will require a successful re-installation to clear
4005 up, but it's when <prgn>dpkg</prgn> starts doing
4006 things that are irreversible.
4011 Any files which were in the old version of the package
4012 but not in the new are removed.
4016 The new file list replaces the old.
4020 The new maintainer scripts replace the old.
4024 Any packages all of whose files have been overwritten
4025 during the installation, and which aren't required for
4026 dependencies, are considered to have been removed.
4027 For each such package
4030 <prgn>dpkg</prgn> calls:
4031 <example compact="compact">
4032 <var>disappearer's-postrm</var> disappear \
4033 <var>overwriter</var> <var>overwriter-version</var>
4037 The package's maintainer scripts are removed.
4040 It is noted in the status database as being in a
4041 sane state, namely not installed (any conffiles
4042 it may have are ignored, rather than being
4043 removed by <prgn>dpkg</prgn>). Note that
4044 disappearing packages do not have their prerm
4045 called, because <prgn>dpkg</prgn> doesn't know
4046 in advance that the package is going to
4053 Any files in the package we're unpacking that are also
4054 listed in the file lists of other packages are removed
4055 from those lists. (This will lobotomize the file list
4056 of the "conflicting" package if there is one.)
4060 The backup files made during installation, above, are
4066 The new package's status is now sane, and recorded as
4071 Here is another point of no return - if the
4072 conflicting package's removal fails we do not unwind
4073 the rest of the installation; the conflicting package
4074 is left in a half-removed limbo.
4079 If there was a conflicting package we go and do the
4080 removal actions (described below), starting with the
4081 removal of the conflicting package's files (any that
4082 are also in the package being installed have already
4083 been removed from the conflicting package's file list,
4084 and so do not get removed now).
4090 <sect id="configdetails"><heading>Details of configuration</heading>
4093 When we configure a package (this happens with <tt>dpkg
4094 --install</tt> and <tt>dpkg --configure</tt>), we first
4095 update any <tt>conffile</tt>s and then call:
4096 <example compact="compact">
4097 <var>postinst</var> configure <var>most-recently-configured-version</var>
4102 No attempt is made to unwind after errors during
4103 configuration. If the configuration fails, the package is in
4104 a "Failed Config" state, and an error message is generated.
4108 If there is no most recently configured version
4109 <prgn>dpkg</prgn> will pass a null argument.
4112 Historical note: Truly ancient (pre-1997) versions of
4113 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4114 (including the angle brackets) in this case. Even older
4115 ones did not pass a second argument at all, under any
4116 circumstance. Note that upgrades using such an old dpkg
4117 version are unlikely to work for other reasons, even if
4118 this old argument behavior is handled by your postinst script.
4124 <sect id="removedetails"><heading>Details of removal and/or
4125 configuration purging</heading>
4131 <example compact="compact">
4132 <var>prerm</var> remove
4136 If prerm fails during replacement due to conflict
4138 <var>conflictor's-postinst</var> abort-remove \
4139 in-favour <var>package</var> <var>new-version</var>
4143 <var>postinst</var> abort-remove
4147 If this fails, the package is in a "Half-Configured"
4148 state, or else it remains "Installed".
4152 The package's files are removed (except <tt>conffile</tt>s).
4155 <example compact="compact">
4156 <var>postrm</var> remove
4160 If it fails, there's no error unwind, and the package is in
4161 an "Half-Installed" state.
4166 All the maintainer scripts except the <prgn>postrm</prgn>
4171 If we aren't purging the package we stop here. Note
4172 that packages which have no <prgn>postrm</prgn> and no
4173 <tt>conffile</tt>s are automatically purged when
4174 removed, as there is no difference except for the
4175 <prgn>dpkg</prgn> status.
4179 The <tt>conffile</tt>s and any backup files
4180 (<tt>~</tt>-files, <tt>#*#</tt> files,
4181 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4186 <example compact="compact">
4187 <var>postrm</var> purge
4191 If this fails, the package remains in a "Config-Files"
4196 The package's file list is removed.
4205 <chapt id="relationships">
4206 <heading>Declaring relationships between packages</heading>
4208 <sect id="depsyntax">
4209 <heading>Syntax of relationship fields</heading>
4212 These fields all have a uniform syntax. They are a list of
4213 package names separated by commas.
4217 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4218 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4219 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4220 control file fields of the package, which declare
4221 dependencies on other packages, the package names listed may
4222 also include lists of alternative package names, separated
4223 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4224 if any one of the alternative packages is installed, that
4225 part of the dependency is considered to be satisfied.
4229 All of the fields except for <tt>Provides</tt> may restrict
4230 their applicability to particular versions of each named
4231 package. This is done in parentheses after each individual
4232 package name; the parentheses should contain a relation from
4233 the list below followed by a version number, in the format
4234 described in <ref id="f-Version">.
4238 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4239 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4240 strictly earlier, earlier or equal, exactly equal, later or
4241 equal and strictly later, respectively. The deprecated
4242 forms <tt><</tt> and <tt>></tt> were used to mean
4243 earlier/later or equal, rather than strictly earlier/later,
4244 so they should not appear in new packages (though
4245 <prgn>dpkg</prgn> still supports them).
4249 Whitespace may appear at any point in the version
4250 specification subject to the rules in <ref
4251 id="controlsyntax">, and must appear where it's necessary to
4252 disambiguate; it is not otherwise significant. All of the
4253 relationship fields may span multiple lines. For
4254 consistency and in case of future changes to
4255 <prgn>dpkg</prgn> it is recommended that a single space be
4256 used after a version relationship and before a version
4257 number; it is also conventional to put a single space after
4258 each comma, on either side of each vertical bar, and before
4259 each open parenthesis. When wrapping a relationship field, it
4260 is conventional to do so after a comma and before the space
4261 following that comma.
4265 For example, a list of dependencies might appear as:
4266 <example compact="compact">
4269 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4274 All fields that specify build-time relationships
4275 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4276 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4277 may be restricted to a certain set of architectures. This
4278 is indicated in brackets after each individual package name and
4279 the optional version specification. The brackets enclose a
4280 list of Debian architecture names separated by whitespace.
4281 Exclamation marks may be prepended to each of the names.
4282 (It is not permitted for some names to be prepended with
4283 exclamation marks while others aren't.) If the current Debian
4284 host architecture is not in this list and there are no
4285 exclamation marks in the list, or it is in the list with a
4286 prepended exclamation mark, the package name and the
4287 associated version specification are ignored completely for
4288 the purposes of defining the relationships.
4293 <example compact="compact">
4295 Build-Depends-Indep: texinfo
4296 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4297 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4299 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4300 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4301 <tt>gnumach-dev</tt> only on hurd-i386.
4305 If the architecture-restricted dependency is part of a set of
4306 alternatives using <tt>|</tt>, that alternative is ignored
4307 completely on architectures that do not match the restriction.
4309 <example compact="compact">
4310 Build-Depends: foo [!i386] | bar [!amd64]
4312 is equivalent to <tt>bar</tt> on the i386 architecture, to
4313 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4314 bar</tt> on all other architectures.
4318 All fields that specify build-time relationships may also be
4319 restricted to a certain set of architectures using architecture
4320 wildcards. The syntax for declaring such restrictions is the
4321 same as declaring restrictions using a certain set of
4322 architectures without architecture wildcards. For example:
4323 <example compact="compact">
4324 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4326 is equivalent to <tt>foo</tt> on architectures using the Linux
4327 kernel and any cpu, <tt>bar</tt> on architectures using any
4328 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4329 using a kernel other than Linux.
4333 Note that the binary package relationship fields such as
4334 <tt>Depends</tt> appear in one of the binary package
4335 sections of the control file, whereas the build-time
4336 relationships such as <tt>Build-Depends</tt> appear in the
4337 source package section of the control file (which is the
4342 <sect id="binarydeps">
4343 <heading>Binary Dependencies - <tt>Depends</tt>,
4344 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4345 <tt>Pre-Depends</tt>
4349 Packages can declare in their control file that they have
4350 certain relationships to other packages - for example, that
4351 they may not be installed at the same time as certain other
4352 packages, and/or that they depend on the presence of others.
4356 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4357 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4358 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4359 <tt>Breaks</tt> is described in <ref id="breaks">, and
4360 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4361 rest are described below.
4365 These seven fields are used to declare a dependency
4366 relationship by one package on another. Except for
4367 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4368 depending (binary) package's control file.
4369 (<tt>Enhances</tt> appears in the recommending package's
4370 control file, and <tt>Breaks</tt> appears in the version of
4371 depended-on package which causes the named package to
4376 A <tt>Depends</tt> field takes effect <em>only</em> when a
4377 package is to be configured. It does not prevent a package
4378 being on the system in an unconfigured state while its
4379 dependencies are unsatisfied, and it is possible to replace
4380 a package whose dependencies are satisfied and which is
4381 properly installed with a different version whose
4382 dependencies are not and cannot be satisfied; when this is
4383 done the depending package will be left unconfigured (since
4384 attempts to configure it will give errors) and will not
4385 function properly. If it is necessary, a
4386 <tt>Pre-Depends</tt> field can be used, which has a partial
4387 effect even when a package is being unpacked, as explained
4388 in detail below. (The other three dependency fields,
4389 <tt>Recommends</tt>, <tt>Suggests</tt> and
4390 <tt>Enhances</tt>, are only used by the various front-ends
4391 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4392 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4396 For this reason packages in an installation run are usually
4397 all unpacked first and all configured later; this gives
4398 later versions of packages with dependencies on later
4399 versions of other packages the opportunity to have their
4400 dependencies satisfied.
4404 In case of circular dependencies, since installation or
4405 removal order honoring the dependency order can't be
4406 established, dependency loops are broken at some point
4407 (based on rules below), and some packages may not be able to
4408 rely on their dependencies being present when being
4409 installed or removed, depending on which side of the break
4410 of the circular dependency loop they happen to be on. If one
4411 of the packages in the loop has no postinst script, then the
4412 cycle will be broken at that package, so as to ensure that
4413 all postinst scripts run with the dependencies properly
4414 configured if this is possible. Otherwise the breaking point
4419 The <tt>Depends</tt> field thus allows package maintainers
4420 to impose an order in which packages should be configured.
4424 The meaning of the five dependency fields is as follows:
4426 <tag><tt>Depends</tt></tag>
4429 This declares an absolute dependency. A package will
4430 not be configured unless all of the packages listed in
4431 its <tt>Depends</tt> field have been correctly
4436 The <tt>Depends</tt> field should be used if the
4437 depended-on package is required for the depending
4438 package to provide a significant amount of
4443 The <tt>Depends</tt> field should also be used if the
4444 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4445 <prgn>postrm</prgn> scripts require the package to be
4446 present in order to run. Note, however, that the
4447 <prgn>postrm</prgn> cannot rely on any non-essential
4448 packages to be present during the <tt>purge</tt>
4452 <tag><tt>Recommends</tt></tag>
4455 This declares a strong, but not absolute, dependency.
4459 The <tt>Recommends</tt> field should list packages
4460 that would be found together with this one in all but
4461 unusual installations.
4465 <tag><tt>Suggests</tt></tag>
4467 This is used to declare that one package may be more
4468 useful with one or more others. Using this field
4469 tells the packaging system and the user that the
4470 listed packages are related to this one and can
4471 perhaps enhance its usefulness, but that installing
4472 this one without them is perfectly reasonable.
4475 <tag><tt>Enhances</tt></tag>
4477 This field is similar to Suggests but works in the
4478 opposite direction. It is used to declare that a
4479 package can enhance the functionality of another
4483 <tag><tt>Pre-Depends</tt></tag>
4486 This field is like <tt>Depends</tt>, except that it
4487 also forces <prgn>dpkg</prgn> to complete installation
4488 of the packages named before even starting the
4489 installation of the package which declares the
4490 pre-dependency, as follows:
4494 When a package declaring a pre-dependency is about to
4495 be <em>unpacked</em> the pre-dependency can be
4496 satisfied if the depended-on package is either fully
4497 configured, <em>or even if</em> the depended-on
4498 package(s) are only unpacked or in the "Half-Configured"
4499 state, provided that they have been configured
4500 correctly at some point in the past (and not removed
4501 or partially removed since). In this case, both the
4502 previously-configured and currently unpacked or
4503 "Half-Configured" versions must satisfy any version
4504 clause in the <tt>Pre-Depends</tt> field.
4508 When the package declaring a pre-dependency is about
4509 to be <em>configured</em>, the pre-dependency will be
4510 treated as a normal <tt>Depends</tt>, that is, it will
4511 be considered satisfied only if the depended-on
4512 package has been correctly configured.
4516 <tt>Pre-Depends</tt> should be used sparingly,
4517 preferably only by packages whose premature upgrade or
4518 installation would hamper the ability of the system to
4519 continue with any upgrade that might be in progress.
4523 <tt>Pre-Depends</tt> are also required if the
4524 <prgn>preinst</prgn> script depends on the named
4525 package. It is best to avoid this situation if
4533 When selecting which level of dependency to use you should
4534 consider how important the depended-on package is to the
4535 functionality of the one declaring the dependency. Some
4536 packages are composed of components of varying degrees of
4537 importance. Such a package should list using
4538 <tt>Depends</tt> the package(s) which are required by the
4539 more important components. The other components'
4540 requirements may be mentioned as Suggestions or
4541 Recommendations, as appropriate to the components' relative
4547 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4550 When one binary package declares that it breaks another,
4551 <prgn>dpkg</prgn> will refuse to allow the package which
4552 declares <tt>Breaks</tt> be installed unless the broken
4553 package is deconfigured first, and it will refuse to
4554 allow the broken package to be reconfigured.
4558 A package will not be regarded as causing breakage merely
4559 because its configuration files are still installed; it must
4560 be at least "Half-Installed".
4564 A special exception is made for packages which declare that
4565 they break their own package name or a virtual package which
4566 they provide (see below): this does not count as a real
4571 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4572 version clause; such a <tt>Breaks</tt> is introduced in the
4573 version of an (implicit or explicit) dependency which
4574 violates an assumption or reveals a bug in earlier versions
4575 of the broken package. This use of <tt>Breaks</tt> will
4576 inform higher-level package management tools that broken
4577 package must be upgraded before the new one.
4581 If the breaking package also overwrites some files from the
4582 older package, it should use <tt>Replaces</tt> (not
4583 <tt>Conflicts</tt>) to ensure this goes smoothly.
4587 <sect id="conflicts">
4588 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4591 When one binary package declares a conflict with another
4592 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4593 refuse to allow them to be installed on the system at the
4598 If one package is to be installed, the other must be removed
4599 first - if the package being installed is marked as
4600 replacing (see <ref id="replaces">) the one on the system,
4601 or the one on the system is marked as deselected, or both
4602 packages are marked <tt>Essential</tt>, then
4603 <prgn>dpkg</prgn> will automatically remove the package
4604 which is causing the conflict, otherwise it will halt the
4605 installation of the new package with an error. This
4606 mechanism is specifically designed to produce an error when
4607 the installed package is <tt>Essential</tt>, but the new
4612 A package will not cause a conflict merely because its
4613 configuration files are still installed; it must be at least
4618 A special exception is made for packages which declare a
4619 conflict with their own package name, or with a virtual
4620 package which they provide (see below): this does not
4621 prevent their installation, and allows a package to conflict
4622 with others providing a replacement for it. You use this
4623 feature when you want the package in question to be the only
4624 package providing some feature.
4628 A <tt>Conflicts</tt> entry should almost never have an
4629 "earlier than" version clause. This would prevent
4630 <prgn>dpkg</prgn> from upgrading or installing the package
4631 which declared such a conflict until the upgrade or removal
4632 of the conflicted-with package had been completed. Instead,
4633 <tt>Breaks</tt> may be used.
4637 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4641 As well as the names of actual ("concrete") packages, the
4642 package relationship fields <tt>Depends</tt>,
4643 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4644 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4645 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4646 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4647 may mention "virtual packages".
4651 A <em>virtual package</em> is one which appears in the
4652 <tt>Provides</tt> control file field of another package.
4653 The effect is as if the package(s) which provide a
4654 particular virtual package name had been listed by name
4655 everywhere the virtual package name appears. (See also <ref
4660 If there are both concrete and virtual packages of the same
4661 name, then the dependency may be satisfied (or the conflict
4662 caused) by either the concrete package with the name in
4663 question or any other concrete package which provides the
4664 virtual package with the name in question. This is so that,
4665 for example, supposing we have
4666 <example compact="compact">
4669 </example> and someone else releases an enhanced version of
4670 the <tt>bar</tt> package they can say:
4671 <example compact="compact">
4675 and the <tt>bar-plus</tt> package will now also satisfy the
4676 dependency for the <tt>foo</tt> package.
4680 If a relationship field has a version number attached
4681 then only real packages will be considered to see whether
4682 the relationship is satisfied (or the prohibition violated,
4683 for a conflict or breakage) - it is assumed that a real
4684 package which provides the virtual package is not of the
4685 "right" version. So, a <tt>Provides</tt> field may not
4686 contain version numbers, and the version number of the
4687 concrete package which provides a particular virtual package
4688 will not be looked at when considering a dependency on or
4689 conflict with the virtual package name.
4693 It is likely that the ability will be added in a future
4694 release of <prgn>dpkg</prgn> to specify a version number for
4695 each virtual package it provides. This feature is not yet
4696 present, however, and is expected to be used only
4701 If you want to specify which of a set of real packages
4702 should be the default to satisfy a particular dependency on
4703 a virtual package, you should list the real package as an
4704 alternative before the virtual one.
4709 <sect id="replaces"><heading>Overwriting files and replacing
4710 packages - <tt>Replaces</tt></heading>
4713 Packages can declare in their control file that they should
4714 overwrite files in certain other packages, or completely
4715 replace other packages. The <tt>Replaces</tt> control file
4716 field has these two distinct purposes.
4719 <sect1><heading>Overwriting files in other packages</heading>
4722 Firstly, as mentioned before, it is usually an error for a
4723 package to contain files which are on the system in
4728 However, if the overwriting package declares that it
4729 <tt>Replaces</tt> the one containing the file being
4730 overwritten, then <prgn>dpkg</prgn> will replace the file
4731 from the old package with that from the new. The file
4732 will no longer be listed as "owned" by the old package.
4736 If a package is completely replaced in this way, so that
4737 <prgn>dpkg</prgn> does not know of any files it still
4738 contains, it is considered to have "disappeared". It will
4739 be marked as not wanted on the system (selected for
4740 removal) and not installed. Any <tt>conffile</tt>s
4741 details noted for the package will be ignored, as they
4742 will have been taken over by the overwriting package. The
4743 package's <prgn>postrm</prgn> script will be run with a
4744 special argument to allow the package to do any final
4745 cleanup required. See <ref id="mscriptsinstact">.
4748 Replaces is a one way relationship -- you have to
4749 install the replacing package after the replaced
4756 For this usage of <tt>Replaces</tt>, virtual packages (see
4757 <ref id="virtual">) are not considered when looking at a
4758 <tt>Replaces</tt> field - the packages declared as being
4759 replaced must be mentioned by their real names.
4763 Furthermore, this usage of <tt>Replaces</tt> only takes
4764 effect when both packages are at least partially on the
4765 system at once, so that it can only happen if they do not
4766 conflict or if the conflict has been overridden.
4771 <sect1><heading>Replacing whole packages, forcing their
4775 Secondly, <tt>Replaces</tt> allows the packaging system to
4776 resolve which package should be removed when there is a
4777 conflict - see <ref id="conflicts">. This usage only
4778 takes effect when the two packages <em>do</em> conflict,
4779 so that the two usages of this field do not interfere with
4784 In this situation, the package declared as being replaced
4785 can be a virtual package, so for example, all mail
4786 transport agents (MTAs) would have the following fields in
4787 their control files:
4788 <example compact="compact">
4789 Provides: mail-transport-agent
4790 Conflicts: mail-transport-agent
4791 Replaces: mail-transport-agent
4793 ensuring that only one MTA can be installed at any one
4798 <sect id="sourcebinarydeps">
4799 <heading>Relationships between source and binary packages -
4800 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4801 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4805 Source packages that require certain binary packages to be
4806 installed or absent at the time of building the package
4807 can declare relationships to those binary packages.
4811 This is done using the <tt>Build-Depends</tt>,
4812 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4813 <tt>Build-Conflicts-Indep</tt> control file fields.
4817 Build-dependencies on "build-essential" binary packages can be
4818 omitted. Please see <ref id="pkg-relations"> for more information.
4822 The dependencies and conflicts they define must be satisfied
4823 (as defined earlier for binary packages) in order to invoke
4824 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4826 If you make "build-arch" or "binary-arch", you need
4827 Build-Depends. If you make "build-indep" or
4828 "binary-indep", you need Build-Depends and
4829 Build-Depends-Indep. If you make "build" or "binary",
4833 There is no Build-Depends-Arch; this role is essentially
4834 met with Build-Depends. Anyone building the
4835 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4836 is basically assumed to be building the whole package
4837 anyway and so installs all build dependencies. The
4838 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4839 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4840 does not yet know how to check for its existence) and
4841 <tt>binary-arch</tt>.
4844 The purpose of the original split, I recall, was so that
4845 the autobuilders wouldn't need to install extra packages
4846 needed only for the binary-indep targets. But without a
4847 build-arch/build-indep split, this didn't work, since
4848 most of the work is done in the build target, not in the
4854 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4856 The <tt>Build-Depends</tt> and
4857 <tt>Build-Conflicts</tt> fields must be satisfied when
4858 any of the following targets is invoked:
4859 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4860 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4861 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4863 <tag><tt>Build-Depends-Indep</tt>,
4864 <tt>Build-Conflicts-Indep</tt></tag>
4866 The <tt>Build-Depends-Indep</tt> and
4867 <tt>Build-Conflicts-Indep</tt> fields must be
4868 satisfied when any of the following targets is
4869 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4870 <tt>binary</tt> and <tt>binary-indep</tt>.
4880 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4883 Packages containing shared libraries must be constructed with
4884 a little care to make sure that the shared library is always
4885 available. This is especially important for packages whose
4886 shared libraries are vitally important, such as the C library
4887 (currently <tt>libc6</tt>).
4891 Packages involving shared libraries should be split up into
4892 several binary packages. This section mostly deals with how
4893 this separation is to be accomplished; rules for files within
4894 the shared library packages are in <ref id="libraries"> instead.
4897 <sect id="sharedlibs-runtime">
4898 <heading>Run-time shared libraries</heading>
4901 The run-time shared library needs to be placed in a package
4902 whose name changes whenever the shared object version
4905 Since it is common place to install several versions of a
4906 package that just provides shared libraries, it is a
4907 good idea that the library package should not
4908 contain any extraneous non-versioned files, unless they
4909 happen to be in versioned directories.</p>
4911 The most common mechanism is to place it in a package
4913 <package><var>libraryname</var><var>soversion</var></package>,
4914 where <file><var>soversion</var></file> is the version number
4915 in the soname of the shared library<footnote>
4916 The soname is the shared object name: it's the thing
4917 that has to match exactly between building an executable
4918 and running it for the dynamic linker to be able run the
4919 program. For example, if the soname of the library is
4920 <file>libfoo.so.6</file>, the library package would be
4921 called <file>libfoo6</file>.
4923 Alternatively, if it would be confusing to directly append
4924 <var>soversion</var> to <var>libraryname</var> (e.g. because
4925 <var>libraryname</var> itself ends in a number), you may use
4926 <package><var>libraryname</var>-<var>soversion</var></package> and
4927 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4932 If you have several shared libraries built from the same
4933 source tree you may lump them all together into a single
4934 shared library package, provided that you change all of
4935 their sonames at once (so that you don't get filename
4936 clashes if you try to install different versions of the
4937 combined shared libraries package).
4941 The package should install the shared libraries under
4942 their normal names. For example, the <package>libgdbm3</package>
4943 package should install <file>libgdbm.so.3.0.0</file> as
4944 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4945 renamed or re-linked by any <prgn>prerm</prgn> or
4946 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4947 of renaming things safely without affecting running programs,
4948 and attempts to interfere with this are likely to lead to
4953 Shared libraries should not be installed executable, since
4954 the dynamic linker does not require this and trying to
4955 execute a shared library usually results in a core dump.
4959 The run-time library package should include the symbolic link that
4960 <prgn>ldconfig</prgn> would create for the shared libraries.
4961 For example, the <package>libgdbm3</package> package should include
4962 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4963 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4964 linker (for example <prgn>ld.so</prgn> or
4965 <prgn>ld-linux.so.*</prgn>) can find the library between the
4966 time that <prgn>dpkg</prgn> installs it and the time that
4967 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4969 The package management system requires the library to be
4970 placed before the symbolic link pointing to it in the
4971 <file>.deb</file> file. This is so that when
4972 <prgn>dpkg</prgn> comes to install the symlink
4973 (overwriting the previous symlink pointing at an older
4974 version of the library), the new shared library is already
4975 in place. In the past, this was achieved by creating the
4976 library in the temporary packaging directory before
4977 creating the symlink. Unfortunately, this was not always
4978 effective, since the building of the tar file in the
4979 <file>.deb</file> depended on the behavior of the underlying
4980 file system. Some file systems (such as reiserfs) reorder
4981 the files so that the order of creation is forgotten.
4982 Since version 1.7.0, <prgn>dpkg</prgn>
4983 reorders the files itself as necessary when building a
4984 package. Thus it is no longer important to concern
4985 oneself with the order of file creation.
4989 <sect1 id="ldconfig">
4990 <heading><tt>ldconfig</tt></heading>
4993 Any package installing shared libraries in one of the default
4994 library directories of the dynamic linker (which are currently
4995 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
4996 listed in <file>/etc/ld.so.conf</file><footnote>
4998 <list compact="compact">
4999 <item>/usr/local/lib</item>
5000 <item>/usr/lib/libc5-compat</item>
5001 <item>/lib/libc5-compat</item>
5004 must use <prgn>ldconfig</prgn> to update the shared library
5009 The package maintainer scripts must only call
5010 <prgn>ldconfig</prgn> under these circumstances:
5011 <list compact="compact">
5012 <item>When the <prgn>postinst</prgn> script is run with a
5013 first argument of <tt>configure</tt>, the script must call
5014 <prgn>ldconfig</prgn>, and may optionally invoke
5015 <prgn>ldconfig</prgn> at other times.
5017 <item>When the <prgn>postrm</prgn> script is run with a
5018 first argument of <tt>remove</tt>, the script should call
5019 <prgn>ldconfig</prgn>.
5024 During install or upgrade, the preinst is called before
5025 the new files are installed, so calling "ldconfig" is
5026 pointless. The preinst of an existing package can also be
5027 called if an upgrade fails. However, this happens during
5028 the critical time when a shared libs may exist on-disk
5029 under a temporary name. Thus, it is dangerous and
5030 forbidden by current policy to call "ldconfig" at this
5035 When a package is installed or upgraded, "postinst
5036 configure" runs after the new files are safely on-disk.
5037 Since it is perfectly safe to invoke ldconfig
5038 unconditionally in a postinst, it is OK for a package to
5039 simply put ldconfig in its postinst without checking the
5040 argument. The postinst can also be called to recover from
5041 a failed upgrade. This happens before any new files are
5042 unpacked, so there is no reason to call "ldconfig" at this
5047 For a package that is being removed, prerm is
5048 called with all the files intact, so calling ldconfig is
5049 useless. The other calls to "prerm" happen in the case of
5050 upgrade at a time when all the files of the old package
5051 are on-disk, so again calling "ldconfig" is pointless.
5055 postrm, on the other hand, is called with the "remove"
5056 argument just after the files are removed, so this is
5057 the proper time to call "ldconfig" to notify the system
5058 of the fact that the shared libraries from the package
5059 are removed. The postrm can be called at several other
5060 times. At the time of "postrm purge", "postrm
5061 abort-install", or "postrm abort-upgrade", calling
5062 "ldconfig" is useless because the shared lib files are
5063 not on-disk. However, when "postrm" is invoked with
5064 arguments "upgrade", "failed-upgrade", or "disappear", a
5065 shared lib may exist on-disk under a temporary filename.
5073 <sect id="sharedlibs-support-files">
5074 <heading>Shared library support files</heading>
5077 If your package contains files whose names do not change with
5078 each change in the library shared object version, you must not
5079 put them in the shared library package. Otherwise, several
5080 versions of the shared library cannot be installed at the same
5081 time without filename clashes, making upgrades and transitions
5082 unnecessarily difficult.
5086 It is recommended that supporting files and run-time support
5087 programs that do not need to be invoked manually by users, but
5088 are nevertheless required for the package to function, be placed
5089 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5090 preferably under <file>/usr/lib/</file><var>package-name</var>.
5091 If the program or file is architecture independent, the
5092 recommendation is for it to be placed in a subdirectory of
5093 <file>/usr/share</file> instead, preferably under
5094 <file>/usr/share/</file><var>package-name</var>. Following the
5095 <var>package-name</var> naming convention ensures that the file
5096 names change when the shared object version changes.
5100 Run-time support programs that use the shared library but are
5101 not required for the library to function or files used by the
5102 shared library that can be used by any version of the shared
5103 library package should instead be put in a separate package.
5104 This package might typically be named
5105 <package><var>libraryname</var>-tools</package>; note the
5106 absence of the <var>soversion</var> in the package name.
5110 Files and support programs only useful when compiling software
5111 against the library should be included in the development
5112 package for the library.<footnote>
5113 For example, a <file><var>package-name</var>-config</file>
5114 script or <package>pkg-config</package> configuration files.
5119 <sect id="sharedlibs-static">
5120 <heading>Static libraries</heading>
5123 The static library (<file><var>libraryname.a</var></file>)
5124 is usually provided in addition to the shared version.
5125 It is placed into the development package (see below).
5129 In some cases, it is acceptable for a library to be
5130 available in static form only; these cases include:
5132 <item>libraries for languages whose shared library support
5133 is immature or unstable</item>
5134 <item>libraries whose interfaces are in flux or under
5135 development (commonly the case when the library's
5136 major version number is zero, or where the ABI breaks
5137 across patchlevels)</item>
5138 <item>libraries which are explicitly intended to be
5139 available only in static form by their upstream
5144 <sect id="sharedlibs-dev">
5145 <heading>Development files</heading>
5148 The development files associated to a shared library need to be
5149 placed in a package called
5150 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5151 or if you prefer only to support one development version at a
5152 time, <package><var>libraryname</var>-dev</package>.
5156 In case several development versions of a library exist, you may
5157 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5158 <ref id="conflicts">) to ensure that the user only installs one
5159 development version at a time (as different development versions are
5160 likely to have the same header files in them, which would cause a
5161 filename clash if both were installed).
5165 The development package should contain a symlink for the associated
5166 shared library without a version number. For example, the
5167 <package>libgdbm-dev</package> package should include a symlink
5168 from <file>/usr/lib/libgdbm.so</file> to
5169 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5170 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5171 <file>libgdbm.so</file> when compiling dynamically.
5175 <sect id="sharedlibs-intradeps">
5176 <heading>Dependencies between the packages of the same library</heading>
5179 Typically the development version should have an exact
5180 version dependency on the runtime library, to make sure that
5181 compilation and linking happens correctly. The
5182 <tt>${binary:Version}</tt> substitution variable can be
5183 useful for this purpose.
5185 Previously, <tt>${Source-Version}</tt> was used, but its name
5186 was confusing and it has been deprecated since dpkg 1.13.19.
5191 <sect id="sharedlibs-shlibdeps">
5192 <heading>Dependencies between the library and other packages -
5193 the <tt>shlibs</tt> system</heading>
5196 If a package contains a binary or library which links to a
5197 shared library, we must ensure that when the package is
5198 installed on the system, all of the libraries needed are
5199 also installed. This requirement led to the creation of the
5200 <tt>shlibs</tt> system, which is very simple in its design:
5201 any package which <em>provides</em> a shared library also
5202 provides information on the package dependencies required to
5203 ensure the presence of this library, and any package which
5204 <em>uses</em> a shared library uses this information to
5205 determine the dependencies it requires. The files which
5206 contain the mapping from shared libraries to the necessary
5207 dependency information are called <file>shlibs</file> files.
5211 Thus, when a package is built which contains any shared
5212 libraries, it must provide a <file>shlibs</file> file for other
5213 packages to use, and when a package is built which contains
5214 any shared libraries or compiled binaries, it must run
5215 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5216 on these to determine the libraries used and hence the
5217 dependencies needed by this package.<footnote>
5219 In the past, the shared libraries linked to were
5220 determined by calling <prgn>ldd</prgn>, but now
5221 <prgn>objdump</prgn> is used to do this. The only
5222 change this makes to package building is that
5223 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5224 libraries, whereas in the past this was unnecessary.
5225 The rest of this footnote explains the advantage that
5230 We say that a binary <tt>foo</tt> <em>directly</em> uses
5231 a library <tt>libbar</tt> if it is explicitly linked
5232 with that library (that is, it uses the flag
5233 <tt>-lbar</tt> during the linking stage). Other
5234 libraries that are needed by <tt>libbar</tt> are linked
5235 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5236 linker will load them automatically when it loads
5237 <tt>libbar</tt>. A package should depend on
5238 the libraries it directly uses, and the dependencies for
5239 those libraries should automatically pull in the other
5244 Unfortunately, the <prgn>ldd</prgn> program shows both
5245 the directly and indirectly used libraries, meaning that
5246 the dependencies determined included both direct and
5247 indirect dependencies. The use of <prgn>objdump</prgn>
5248 avoids this problem by determining only the directly
5253 A good example of where this helps is the following. We
5254 could update <tt>libimlib</tt> with a new version that
5255 supports a new graphics format called dgf (but retaining
5256 the same major version number). If we used the old
5257 <prgn>ldd</prgn> method, every package that uses
5258 <tt>libimlib</tt> would need to be recompiled so it
5259 would also depend on <tt>libdgf</tt> or it wouldn't run
5260 due to missing symbols. However with the new system,
5261 packages using <tt>libimlib</tt> can rely on
5262 <tt>libimlib</tt> itself having the dependency on
5263 <tt>libdgf</tt> and so they would not need rebuilding.
5269 In the following sections, we will first describe where the
5270 various <tt>shlibs</tt> files are to be found, then how to
5271 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5272 file format and how to create them if your package contains a
5277 <heading>The <tt>shlibs</tt> files present on the system</heading>
5280 There are several places where <tt>shlibs</tt> files are
5281 found. The following list gives them in the order in which
5283 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5284 (The first one which gives the required information is used.)
5290 <p><file>debian/shlibs.local</file></p>
5293 This lists overrides for this package. Its use is
5294 described below (see <ref id="shlibslocal">).
5299 <p><file>/etc/dpkg/shlibs.override</file></p>
5302 This lists global overrides. This list is normally
5303 empty. It is maintained by the local system
5309 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5312 When packages are being built, any
5313 <file>debian/shlibs</file> files are copied into the
5314 control file area of the temporary build directory and
5315 given the name <file>shlibs</file>. These files give
5316 details of any shared libraries included in the
5318 An example may help here. Let us say that the
5319 source package <tt>foo</tt> generates two binary
5320 packages, <tt>libfoo2</tt> and
5321 <tt>foo-runtime</tt>. When building the binary
5322 packages, the two packages are created in the
5323 directories <file>debian/libfoo2</file> and
5324 <file>debian/foo-runtime</file> respectively.
5325 (<file>debian/tmp</file> could be used instead of one
5326 of these.) Since <tt>libfoo2</tt> provides the
5327 <tt>libfoo</tt> shared library, it will require a
5328 <tt>shlibs</tt> file, which will be installed in
5329 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5331 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5332 when <prgn>dpkg-shlibdeps</prgn> is run on the
5334 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5336 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5337 determine whether <tt>foo-prog</tt>'s library
5338 dependencies are satisfied by any of the libraries
5339 provided by <tt>libfoo2</tt>. For this reason,
5340 <prgn>dpkg-shlibdeps</prgn> must only be run once
5341 all of the individual binary packages'
5342 <tt>shlibs</tt> files have been installed into the
5349 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5352 These are the <file>shlibs</file> files corresponding to
5353 all of the packages installed on the system, and are
5354 maintained by the relevant package maintainers.
5359 <p><file>/etc/dpkg/shlibs.default</file></p>
5362 This file lists any shared libraries whose packages
5363 have failed to provide correct <file>shlibs</file> files.
5364 It was used when the <file>shlibs</file> setup was first
5365 introduced, but it is now normally empty. It is
5366 maintained by the <tt>dpkg</tt> maintainer.
5374 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5375 <file>shlibs</file> files</heading>
5379 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5380 into your <file>debian/rules</file> file. If your package
5381 contains only compiled binaries and libraries (but no scripts),
5382 you can use a command such as:
5383 <example compact="compact">
5384 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5385 debian/tmp/usr/lib/*
5387 Otherwise, you will need to explicitly list the compiled
5388 binaries and libraries.<footnote>
5389 If you are using <tt>debhelper</tt>, the
5390 <prgn>dh_shlibdeps</prgn> program will do this work for
5391 you. It will also correctly handle multi-binary
5397 This command puts the dependency information into the
5398 <file>debian/substvars</file> file, which is then used by
5399 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5400 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5401 field in the control file for this to work.
5405 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5406 done. If it does complain you might need to create your own
5407 <file>debian/shlibs.local</file> file, as explained below (see
5408 <ref id="shlibslocal">).
5412 If you have multiple binary packages, you will need to call
5413 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5414 compiled libraries or binaries. In such a case, you will
5415 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5416 utilities to specify a different <file>substvars</file> file.
5420 If you are creating a udeb for use in the Debian Installer,
5421 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5422 should use the dependency line of type <tt>udeb</tt> by
5423 adding the <tt>-tudeb</tt> option<footnote>
5424 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5425 will automatically add this option if it knows it is
5427 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5428 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5429 fall back to the regular dependency line.
5433 For more details on dpkg-shlibdeps, please see
5434 <ref id="pkg-dpkg-shlibdeps"> and
5435 <manref name="dpkg-shlibdeps" section="1">.
5440 <heading>The <file>shlibs</file> File Format</heading>
5443 Each <file>shlibs</file> file has the same format. Lines
5444 beginning with <tt>#</tt> are considered to be comments and
5445 are ignored. Each line is of the form:
5446 <example compact="compact">
5447 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5452 We will explain this by reference to the example of the
5453 <tt>zlib1g</tt> package, which (at the time of writing)
5454 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5458 <var>type</var> is an optional element that indicates the type
5459 of package for which the line is valid. The only type currently
5460 in use is <tt>udeb</tt>. The colon and space after the type are
5465 <var>library-name</var> is the name of the shared library,
5466 in this case <tt>libz</tt>. (This must match the name part
5467 of the soname, see below.)
5471 <var>soname-version</var> is the version part of the soname of
5472 the library. The soname is the thing that must exactly match
5473 for the library to be recognized by the dynamic linker, and is
5475 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5476 example, <tt>libz.so.1</tt>.<footnote>
5477 This can be determined using the command
5478 <example compact="compact">
5479 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5482 The version part is the part which comes after
5483 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5487 <var>dependencies</var> has the same syntax as a dependency
5488 field in a binary package control file. It should give
5489 details of which packages are required to satisfy a binary
5490 built against the version of the library contained in the
5491 package. See <ref id="depsyntax"> for details.
5495 In our example, if the first version of the <tt>zlib1g</tt>
5496 package which contained a minor number of at least
5497 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5498 <tt>shlibs</tt> entry for this library could say:
5499 <example compact="compact">
5500 libz 1 zlib1g (>= 1:1.1.3)
5502 The version-specific dependency is to avoid warnings from
5503 the dynamic linker about using older shared libraries with
5508 As zlib1g also provides a udeb containing the shared library,
5509 there would also be a second line:
5510 <example compact="compact">
5511 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5517 <heading>Providing a <file>shlibs</file> file</heading>
5520 If your package provides a shared library, you need to create
5521 a <file>shlibs</file> file following the format described above.
5522 It is usual to call this file <file>debian/shlibs</file> (but if
5523 you have multiple binary packages, you might want to call it
5524 <file>debian/shlibs.<var>package</var></file> instead). Then
5525 let <file>debian/rules</file> install it in the control area:
5526 <example compact="compact">
5527 install -m644 debian/shlibs debian/tmp/DEBIAN
5529 or, in the case of a multi-binary package:
5530 <example compact="compact">
5531 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5533 An alternative way of doing this is to create the
5534 <file>shlibs</file> file in the control area directly from
5535 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5536 file at all,<footnote>
5537 This is what <prgn>dh_makeshlibs</prgn> in the
5538 <tt>debhelper</tt> suite does. If your package also has a udeb
5539 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5540 automatically generate the <tt>udeb:</tt> lines if you specify
5541 the name of the udeb with the <tt>--add-udeb</tt> option.
5543 since the <file>debian/shlibs</file> file itself is ignored by
5544 <prgn>dpkg-shlibdeps</prgn>.
5548 As <prgn>dpkg-shlibdeps</prgn> reads the
5549 <file>DEBIAN/shlibs</file> files in all of the binary packages
5550 being built from this source package, all of the
5551 <file>DEBIAN/shlibs</file> files should be installed before
5552 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5557 <sect1 id="shlibslocal">
5558 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5561 This file is intended only as a <em>temporary</em> fix if
5562 your binaries or libraries depend on a library whose package
5563 does not yet provide a correct <file>shlibs</file> file.
5567 We will assume that you are trying to package a binary
5568 <tt>foo</tt>. When you try running
5569 <prgn>dpkg-shlibdeps</prgn> you get the following error
5570 message (<tt>-O</tt> displays the dependency information on
5571 <tt>stdout</tt> instead of writing it to
5572 <tt>debian/substvars</tt>, and the lines have been wrapped
5573 for ease of reading):
5574 <example compact="compact">
5575 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5576 dpkg-shlibdeps: warning: unable to find dependency
5577 information for shared library libbar (soname 1,
5578 path /usr/lib/libbar.so.1, dependency field Depends)
5579 shlibs:Depends=libc6 (>= 2.2.2-2)
5581 You can then run <prgn>ldd</prgn> on the binary to find the
5582 full location of the library concerned:
5583 <example compact="compact">
5585 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5586 libc.so.6 => /lib/libc.so.6 (0x40032000)
5587 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5589 So the <prgn>foo</prgn> binary depends on the
5590 <prgn>libbar</prgn> shared library, but no package seems to
5591 provide a <file>*.shlibs</file> file handling
5592 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5593 determine the package responsible:
5594 <example compact="compact">
5595 $ dpkg -S /usr/lib/libbar.so.1
5596 bar1: /usr/lib/libbar.so.1
5597 $ dpkg -s bar1 | grep Version
5600 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5601 is the one we are using. Now we can file a bug against the
5602 <tt>bar1</tt> package and create our own
5603 <file>debian/shlibs.local</file> to locally fix the problem.
5604 Including the following line into your
5605 <file>debian/shlibs.local</file> file:
5606 <example compact="compact">
5607 libbar 1 bar1 (>= 1.0-1)
5609 should allow the package build to work.
5613 As soon as the maintainer of <tt>bar1</tt> provides a
5614 correct <file>shlibs</file> file, you should remove this line
5615 from your <file>debian/shlibs.local</file> file. (You should
5616 probably also then have a versioned <tt>Build-Depends</tt>
5617 on <tt>bar1</tt> to help ensure that others do not have the
5618 same problem building your package.)
5627 <chapt id="opersys"><heading>The Operating System</heading>
5630 <heading>File system hierarchy</heading>
5634 <heading>File System Structure</heading>
5637 The location of all installed files and directories must
5638 comply with the Filesystem Hierarchy Standard (FHS),
5639 version 2.3, with the exceptions noted below, and except
5640 where doing so would violate other terms of Debian
5641 Policy. The following exceptions to the FHS apply:
5646 The optional rules related to user specific
5647 configuration files for applications are stored in
5648 the user's home directory are relaxed. It is
5649 recommended that such files start with the
5650 '<tt>.</tt>' character (a "dot file"), and if an
5651 application needs to create more than one dot file
5652 then the preferred placement is in a subdirectory
5653 with a name starting with a '.' character, (a "dot
5654 directory"). In this case it is recommended the
5655 configuration files not start with the '.'
5661 The requirement for amd64 to use <file>/lib64</file>
5662 for 64 bit binaries is removed.
5667 The requirement for object files, internal binaries, and
5668 libraries, including <file>libc.so.*</file>, to be located
5669 directly under <file>/lib{,32}</file> and
5670 <file>/usr/lib{,32}</file> is amended, permitting files
5671 to instead be installed to
5672 <file>/lib/<var>triplet</var></file> and
5673 <file>/usr/lib/<var>triplet</var></file>, where
5674 <tt><var>triplet</var></tt> is the value returned by
5675 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5676 architecture of the package. Packages may <em>not</em>
5677 install files to any <var>triplet</var> path other
5678 than the one matching the architecture of that package;
5679 for instance, an <tt>Architecture: amd64</tt> package
5680 containing 32-bit x86 libraries may not install these
5681 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5683 This is necessary in order to reserve the directories for
5684 use in cross-installation of library packages from other
5685 architectures, as part of the planned deployment of
5690 Applications may also use a single subdirectory under
5691 <file>/usr/lib/<var>triplet</var></file>.
5694 The execution time linker/loader, ld*, must still be made
5695 available in the existing location under /lib or /lib64
5696 since this is part of the ELF ABI for the architecture.
5701 The requirement that
5702 <file>/usr/local/share/man</file> be "synonymous"
5703 with <file>/usr/local/man</file> is relaxed to a
5708 The requirement that windowmanagers with a single
5709 configuration file call it <file>system.*wmrc</file>
5710 is removed, as is the restriction that the window
5711 manager subdirectory be named identically to the
5712 window manager name itself.
5717 The requirement that boot manager configuration
5718 files live in <file>/etc</file>, or at least are
5719 symlinked there, is relaxed to a recommendation.
5724 The following directories in the root filesystem are
5725 additionally allowed: <file>/sys</file> and
5726 <file>/selinux</file>. <footnote>These directories
5727 are used as mount points to mount virtual filesystems
5728 to get access to kernel information.</footnote>
5735 The version of this document referred here can be
5736 found in the <tt>debian-policy</tt> package or on <url
5737 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5738 name="FHS (Debian copy)"> alongside this manual (or, if
5739 you have the <package>debian-policy</package> installed,
5741 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5742 (local copy)">). The
5743 latest version, which may be a more recent version, may
5745 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5746 Specific questions about following the standard may be
5747 asked on the <tt>debian-devel</tt> mailing list, or
5748 referred to the FHS mailing list (see the
5749 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5755 <heading>Site-specific programs</heading>
5758 As mandated by the FHS, packages must not place any
5759 files in <file>/usr/local</file>, either by putting them in
5760 the file system archive to be unpacked by <prgn>dpkg</prgn>
5761 or by manipulating them in their maintainer scripts.
5765 However, the package may create empty directories below
5766 <file>/usr/local</file> so that the system administrator knows
5767 where to place site-specific files. These are not
5768 directories <em>in</em> <file>/usr/local</file>, but are
5769 children of directories in <file>/usr/local</file>. These
5770 directories (<file>/usr/local/*/dir/</file>)
5771 should be removed on package removal if they are
5776 Note that this applies only to
5777 directories <em>below</em> <file>/usr/local</file>,
5778 not <em>in</em> <file>/usr/local</file>. Packages must
5779 not create sub-directories in the
5780 directory <file>/usr/local</file> itself, except those
5781 listed in FHS, section 4.5. However, you may create
5782 directories below them as you wish. You must not remove
5783 any of the directories listed in 4.5, even if you created
5788 Since <file>/usr/local</file> can be mounted read-only from a
5789 remote server, these directories must be created and
5790 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5791 maintainer scripts and not be included in the
5792 <file>.deb</file> archive. These scripts must not fail if
5793 either of these operations fail.
5797 For example, the <tt>emacsen-common</tt> package could
5798 contain something like
5799 <example compact="compact">
5800 if [ ! -e /usr/local/share/emacs ]
5802 if mkdir /usr/local/share/emacs 2>/dev/null
5804 chown root:staff /usr/local/share/emacs
5805 chmod 2775 /usr/local/share/emacs
5809 in its <prgn>postinst</prgn> script, and
5810 <example compact="compact">
5811 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5812 rmdir /usr/local/share/emacs 2>/dev/null || true
5814 in the <prgn>prerm</prgn> script. (Note that this form is
5815 used to ensure that if the script is interrupted, the
5816 directory <file>/usr/local/share/emacs</file> will still be
5821 If you do create a directory in <file>/usr/local</file> for
5822 local additions to a package, you should ensure that
5823 settings in <file>/usr/local</file> take precedence over the
5824 equivalents in <file>/usr</file>.
5828 However, because <file>/usr/local</file> and its contents are
5829 for exclusive use of the local administrator, a package
5830 must not rely on the presence or absence of files or
5831 directories in <file>/usr/local</file> for normal operation.
5835 The <file>/usr/local</file> directory itself and all the
5836 subdirectories created by the package should (by default) have
5837 permissions 2775 (group-writable and set-group-id) and be
5838 owned by <tt>root:staff</tt>.
5843 <heading>The system-wide mail directory</heading>
5845 The system-wide mail directory
5846 is <file>/var/mail</file>. This directory is part of the
5847 base system and should not be owned by any particular mail
5848 agents. The use of the old
5849 location <file>/var/spool/mail</file> is deprecated, even
5850 though the spool may still be physically located there.
5856 <heading>Users and groups</heading>
5859 <heading>Introduction</heading>
5861 The Debian system can be configured to use either plain or
5866 Some user ids (UIDs) and group ids (GIDs) are reserved
5867 globally for use by certain packages. Because some
5868 packages need to include files which are owned by these
5869 users or groups, or need the ids compiled into binaries,
5870 these ids must be used on any Debian system only for the
5871 purpose for which they are allocated. This is a serious
5872 restriction, and we should avoid getting in the way of
5873 local administration policies. In particular, many sites
5874 allocate users and/or local system groups starting at 100.
5878 Apart from this we should have dynamically allocated ids,
5879 which should by default be arranged in some sensible
5880 order, but the behavior should be configurable.
5884 Packages other than <tt>base-passwd</tt> must not modify
5885 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5886 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5891 <heading>UID and GID classes</heading>
5893 The UID and GID numbers are divided into classes as
5899 Globally allocated by the Debian project, the same
5900 on every Debian system. These ids will appear in
5901 the <file>passwd</file> and <file>group</file> files of all
5902 Debian systems, new ids in this range being added
5903 automatically as the <tt>base-passwd</tt> package is
5908 Packages which need a single statically allocated
5909 uid or gid should use one of these; their
5910 maintainers should ask the <tt>base-passwd</tt>
5918 Dynamically allocated system users and groups.
5919 Packages which need a user or group, but can have
5920 this user or group allocated dynamically and
5921 differently on each system, should use <tt>adduser
5922 --system</tt> to create the group and/or user.
5923 <prgn>adduser</prgn> will check for the existence of
5924 the user or group, and if necessary choose an unused
5925 id based on the ranges specified in
5926 <file>adduser.conf</file>.
5930 <tag>1000-59999:</tag>
5933 Dynamically allocated user accounts. By default
5934 <prgn>adduser</prgn> will choose UIDs and GIDs for
5935 user accounts in this range, though
5936 <file>adduser.conf</file> may be used to modify this
5941 <tag>60000-64999:</tag>
5944 Globally allocated by the Debian project, but only
5945 created on demand. The ids are allocated centrally
5946 and statically, but the actual accounts are only
5947 created on users' systems on demand.
5951 These ids are for packages which are obscure or
5952 which require many statically-allocated ids. These
5953 packages should check for and create the accounts in
5954 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5955 <prgn>adduser</prgn> if it has this facility) if
5956 necessary. Packages which are likely to require
5957 further allocations should have a "hole" left after
5958 them in the allocation, to give them room to
5963 <tag>65000-65533:</tag>
5971 User <tt>nobody</tt>. The corresponding gid refers
5972 to the group <tt>nogroup</tt>.
5979 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5980 not</em> be used, because it is the error return
5989 <sect id="sysvinit">
5990 <heading>System run levels and <file>init.d</file> scripts</heading>
5992 <sect1 id="/etc/init.d">
5993 <heading>Introduction</heading>
5996 The <file>/etc/init.d</file> directory contains the scripts
5997 executed by <prgn>init</prgn> at boot time and when the
5998 init state (or "runlevel") is changed (see <manref
5999 name="init" section="8">).
6003 There are at least two different, yet functionally
6004 equivalent, ways of handling these scripts. For the sake
6005 of simplicity, this document describes only the symbolic
6006 link method. However, it must not be assumed by maintainer
6007 scripts that this method is being used, and any automated
6008 manipulation of the various runlevel behaviors by
6009 maintainer scripts must be performed using
6010 <prgn>update-rc.d</prgn> as described below and not by
6011 manually installing or removing symlinks. For information
6012 on the implementation details of the other method,
6013 implemented in the <tt>file-rc</tt> package, please refer
6014 to the documentation of that package.
6018 These scripts are referenced by symbolic links in the
6019 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6020 runlevels, <prgn>init</prgn> looks in the directory
6021 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6022 execute, where <tt><var>n</var></tt> is the runlevel that
6023 is being changed to, or <tt>S</tt> for the boot-up
6028 The names of the links all have the form
6029 <file>S<var>mm</var><var>script</var></file> or
6030 <file>K<var>mm</var><var>script</var></file> where
6031 <var>mm</var> is a two-digit number and <var>script</var>
6032 is the name of the script (this should be the same as the
6033 name of the actual script in <file>/etc/init.d</file>).
6037 When <prgn>init</prgn> changes runlevel first the targets
6038 of the links whose names start with a <tt>K</tt> are
6039 executed, each with the single argument <tt>stop</tt>,
6040 followed by the scripts prefixed with an <tt>S</tt>, each
6041 with the single argument <tt>start</tt>. (The links are
6042 those in the <file>/etc/rc<var>n</var>.d</file> directory
6043 corresponding to the new runlevel.) The <tt>K</tt> links
6044 are responsible for killing services and the <tt>S</tt>
6045 link for starting services upon entering the runlevel.
6049 For example, if we are changing from runlevel 2 to
6050 runlevel 3, init will first execute all of the <tt>K</tt>
6051 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6052 all of the <tt>S</tt> prefixed scripts in that directory.
6053 The links starting with <tt>K</tt> will cause the
6054 referred-to file to be executed with an argument of
6055 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6060 The two-digit number <var>mm</var> is used to determine
6061 the order in which to run the scripts: low-numbered links
6062 have their scripts run first. For example, the
6063 <tt>K20</tt> scripts will be executed before the
6064 <tt>K30</tt> scripts. This is used when a certain service
6065 must be started before another. For example, the name
6066 server <prgn>bind</prgn> might need to be started before
6067 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6068 can set up its access lists. In this case, the script
6069 that starts <prgn>bind</prgn> would have a lower number
6070 than the script that starts <prgn>inn</prgn> so that it
6072 <example compact="compact">
6079 The two runlevels 0 (halt) and 6 (reboot) are slightly
6080 different. In these runlevels, the links with an
6081 <tt>S</tt> prefix are still called after those with a
6082 <tt>K</tt> prefix, but they too are called with the single
6083 argument <tt>stop</tt>.
6087 <sect1 id="writing-init">
6088 <heading>Writing the scripts</heading>
6091 Packages that include daemons for system services should
6092 place scripts in <file>/etc/init.d</file> to start or stop
6093 services at boot time or during a change of runlevel.
6094 These scripts should be named
6095 <file>/etc/init.d/<var>package</var></file>, and they should
6096 accept one argument, saying what to do:
6099 <tag><tt>start</tt></tag>
6100 <item>start the service,</item>
6102 <tag><tt>stop</tt></tag>
6103 <item>stop the service,</item>
6105 <tag><tt>restart</tt></tag>
6106 <item>stop and restart the service if it's already running,
6107 otherwise start the service</item>
6109 <tag><tt>reload</tt></tag>
6110 <item><p>cause the configuration of the service to be
6111 reloaded without actually stopping and restarting
6114 <tag><tt>force-reload</tt></tag>
6115 <item>cause the configuration to be reloaded if the
6116 service supports this, otherwise restart the
6120 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6121 <tt>force-reload</tt> options should be supported by all
6122 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6127 The <file>init.d</file> scripts must ensure that they will
6128 behave sensibly (i.e., returning success and not starting
6129 multiple copies of a service) if invoked with <tt>start</tt>
6130 when the service is already running, or with <tt>stop</tt>
6131 when it isn't, and that they don't kill unfortunately-named
6132 user processes. The best way to achieve this is usually to
6133 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6138 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6139 scripts. Writing correct <file>init.d</file> scripts requires
6140 accepting various error exit statuses when daemons are already
6141 running or already stopped without aborting
6142 the <file>init.d</file> script, and common <file>init.d</file>
6143 function libraries are not safe to call with <tt>set -e</tt>
6145 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6146 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6147 in effect and echoing status messages to the console fails,
6149 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6150 to not use <tt>set -e</tt> and instead check the result of
6151 each command separately.
6155 If a service reloads its configuration automatically (as
6156 in the case of <prgn>cron</prgn>, for example), the
6157 <tt>reload</tt> option of the <file>init.d</file> script
6158 should behave as if the configuration has been reloaded
6163 The <file>/etc/init.d</file> scripts must be treated as
6164 configuration files, either (if they are present in the
6165 package, that is, in the .deb file) by marking them as
6166 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6167 by managing them correctly in the maintainer scripts (see
6168 <ref id="config-files">). This is important since we want
6169 to give the local system administrator the chance to adapt
6170 the scripts to the local system, e.g., to disable a
6171 service without de-installing the package, or to specify
6172 some special command line options when starting a service,
6173 while making sure their changes aren't lost during the next
6178 These scripts should not fail obscurely when the
6179 configuration files remain but the package has been
6180 removed, as configuration files remain on the system after
6181 the package has been removed. Only when <prgn>dpkg</prgn>
6182 is executed with the <tt>--purge</tt> option will
6183 configuration files be removed. In particular, as the
6184 <file>/etc/init.d/<var>package</var></file> script itself is
6185 usually a <tt>conffile</tt>, it will remain on the system
6186 if the package is removed but not purged. Therefore, you
6187 should include a <tt>test</tt> statement at the top of the
6189 <example compact="compact">
6190 test -f <var>program-executed-later-in-script</var> || exit 0
6195 Often there are some variables in the <file>init.d</file>
6196 scripts whose values control the behavior of the scripts,
6197 and which a system administrator is likely to want to
6198 change. As the scripts themselves are frequently
6199 <tt>conffile</tt>s, modifying them requires that the
6200 administrator merge in their changes each time the package
6201 is upgraded and the <tt>conffile</tt> changes. To ease
6202 the burden on the system administrator, such configurable
6203 values should not be placed directly in the script.
6204 Instead, they should be placed in a file in
6205 <file>/etc/default</file>, which typically will have the same
6206 base name as the <file>init.d</file> script. This extra file
6207 should be sourced by the script when the script runs. It
6208 must contain only variable settings and comments in SUSv3
6209 <prgn>sh</prgn> format. It may either be a
6210 <tt>conffile</tt> or a configuration file maintained by
6211 the package maintainer scripts. See <ref id="config-files">
6216 To ensure that vital configurable values are always
6217 available, the <file>init.d</file> script should set default
6218 values for each of the shell variables it uses, either
6219 before sourcing the <file>/etc/default/</file> file or
6220 afterwards using something like the <tt>:
6221 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6222 script must behave sensibly and not fail if the
6223 <file>/etc/default</file> file is deleted.
6227 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6228 as temporary filesystems<footnote>
6229 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6230 options in <file>/etc/default/rcS</file>.
6231 </footnote>, so the <file>init.d</file> scripts must handle this
6232 correctly. This will typically amount to creating any required
6233 subdirectories dynamically when the <file>init.d</file> script
6234 is run, rather than including them in the package and relying on
6235 <prgn>dpkg</prgn> to create them.
6240 <heading>Interfacing with the initscript system</heading>
6243 Maintainers should use the abstraction layer provided by
6244 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6245 programs to deal with initscripts in their packages'
6246 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6247 and <prgn>postrm</prgn>.
6251 Directly managing the /etc/rc?.d links and directly
6252 invoking the <file>/etc/init.d/</file> initscripts should
6253 be done only by packages providing the initscript
6254 subsystem (such as <prgn>sysv-rc</prgn> and
6255 <prgn>file-rc</prgn>).
6259 <heading>Managing the links</heading>
6262 The program <prgn>update-rc.d</prgn> is provided for
6263 package maintainers to arrange for the proper creation and
6264 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6265 or their functional equivalent if another method is being
6266 used. This may be used by maintainers in their packages'
6267 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6271 You must not include any <file>/etc/rc<var>n</var>.d</file>
6272 symbolic links in the actual archive or manually create or
6273 remove the symbolic links in maintainer scripts; you must
6274 use the <prgn>update-rc.d</prgn> program instead. (The
6275 former will fail if an alternative method of maintaining
6276 runlevel information is being used.) You must not include
6277 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6278 in the archive either. (Only the <tt>sysvinit</tt>
6283 By default <prgn>update-rc.d</prgn> will start services in
6284 each of the multi-user state runlevels (2, 3, 4, and 5)
6285 and stop them in the halt runlevel (0), the single-user
6286 runlevel (1) and the reboot runlevel (6). The system
6287 administrator will have the opportunity to customize
6288 runlevels by simply adding, moving, or removing the
6289 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6290 symbolic links are being used, or by modifying
6291 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6296 To get the default behavior for your package, put in your
6297 <prgn>postinst</prgn> script
6298 <example compact="compact">
6299 update-rc.d <var>package</var> defaults
6301 and in your <prgn>postrm</prgn>
6302 <example compact="compact">
6303 if [ "$1" = purge ]; then
6304 update-rc.d <var>package</var> remove
6306 </example>. Note that if your package changes runlevels
6307 or priority, you may have to remove and recreate the links,
6308 since otherwise the old links may persist. Refer to the
6309 documentation of <prgn>update-rc.d</prgn>.
6313 This will use a default sequence number of 20. If it does
6314 not matter when or in which order the <file>init.d</file>
6315 script is run, use this default. If it does, then you
6316 should talk to the maintainer of the <prgn>sysvinit</prgn>
6317 package or post to <tt>debian-devel</tt>, and they will
6318 help you choose a number.
6322 For more information about using <tt>update-rc.d</tt>,
6323 please consult its man page <manref name="update-rc.d"
6329 <heading>Running initscripts</heading>
6331 The program <prgn>invoke-rc.d</prgn> is provided to make
6332 it easier for package maintainers to properly invoke an
6333 initscript, obeying runlevel and other locally-defined
6334 constraints that might limit a package's right to start,
6335 stop and otherwise manage services. This program may be
6336 used by maintainers in their packages' scripts.
6340 The package maintainer scripts must use
6341 <prgn>invoke-rc.d</prgn> to invoke the
6342 <file>/etc/init.d/*</file> initscripts, instead of
6343 calling them directly.
6347 By default, <prgn>invoke-rc.d</prgn> will pass any
6348 action requests (start, stop, reload, restart...) to the
6349 <file>/etc/init.d</file> script, filtering out requests
6350 to start or restart a service out of its intended
6355 Most packages will simply need to change:
6356 <example compact="compact">/etc/init.d/<package>
6357 <action></example> in their <prgn>postinst</prgn>
6358 and <prgn>prerm</prgn> scripts to:
6359 <example compact="compact">
6360 if which invoke-rc.d >/dev/null 2>&1; then
6361 invoke-rc.d <var>package</var> <action>
6363 /etc/init.d/<var>package</var> <action>
6369 A package should register its initscript services using
6370 <prgn>update-rc.d</prgn> before it tries to invoke them
6371 using <prgn>invoke-rc.d</prgn>. Invocation of
6372 unregistered services may fail.
6376 For more information about using
6377 <prgn>invoke-rc.d</prgn>, please consult its man page
6378 <manref name="invoke-rc.d" section="8">.
6384 <heading>Boot-time initialization</heading>
6387 There used to be another directory, <file>/etc/rc.boot</file>,
6388 which contained scripts which were run once per machine
6389 boot. This has been deprecated in favour of links from
6390 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6391 described in <ref id="/etc/init.d">. Packages must not
6392 place files in <file>/etc/rc.boot</file>.
6397 <heading>Example</heading>
6400 An example on which you can base your
6401 <file>/etc/init.d</file> scripts is found in
6402 <file>/etc/init.d/skeleton</file>.
6409 <heading>Console messages from <file>init.d</file> scripts</heading>
6412 This section describes the formats to be used for messages
6413 written to standard output by the <file>/etc/init.d</file>
6414 scripts. The intent is to improve the consistency of
6415 Debian's startup and shutdown look and feel. For this
6416 reason, please look very carefully at the details. We want
6417 the messages to have the same format in terms of wording,
6418 spaces, punctuation and case of letters.
6422 Here is a list of overall rules that should be used for
6423 messages generated by <file>/etc/init.d</file> scripts.
6429 The message should fit in one line (fewer than 80
6430 characters), start with a capital letter and end with
6431 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6435 If the script is performing some time consuming task in
6436 the background (not merely starting or stopping a
6437 program, for instance), an ellipsis (three dots:
6438 <tt>...</tt>) should be output to the screen, with no
6439 leading or tailing whitespace or line feeds.
6443 The messages should appear as if the computer is telling
6444 the user what it is doing (politely :-), but should not
6445 mention "it" directly. For example, instead of:
6446 <example compact="compact">
6447 I'm starting network daemons: nfsd mountd.
6449 the message should say
6450 <example compact="compact">
6451 Starting network daemons: nfsd mountd.
6458 <tt>init.d</tt> script should use the following standard
6459 message formats for the situations enumerated below.
6465 <p>When daemons are started</p>
6468 If the script starts one or more daemons, the output
6469 should look like this (a single line, no leading
6471 <example compact="compact">
6472 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6474 The <var>description</var> should describe the
6475 subsystem the daemon or set of daemons are part of,
6476 while <var>daemon-1</var> up to <var>daemon-n</var>
6477 denote each daemon's name (typically the file name of
6482 For example, the output of <file>/etc/init.d/lpd</file>
6484 <example compact="compact">
6485 Starting printer spooler: lpd.
6490 This can be achieved by saying
6491 <example compact="compact">
6492 echo -n "Starting printer spooler: lpd"
6493 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6496 in the script. If there are more than one daemon to
6497 start, the output should look like this:
6498 <example compact="compact">
6499 echo -n "Starting remote file system services:"
6500 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6501 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6502 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6505 This makes it possible for the user to see what is
6506 happening and when the final daemon has been started.
6507 Care should be taken in the placement of white spaces:
6508 in the example above the system administrators can
6509 easily comment out a line if they don't want to start
6510 a specific daemon, while the displayed message still
6516 <p>When a system parameter is being set</p>
6519 If you have to set up different system parameters
6520 during the system boot, you should use this format:
6521 <example compact="compact">
6522 Setting <var>parameter</var> to "<var>value</var>".
6527 You can use a statement such as the following to get
6529 <example compact="compact">
6530 echo "Setting DNS domainname to \"$domainname\"."
6535 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6536 for the left and right quotation marks. A grave accent
6537 (<tt>`</tt>) is not a quote character; neither is an
6538 apostrophe (<tt>'</tt>).
6543 <p>When a daemon is stopped or restarted</p>
6546 When you stop or restart a daemon, you should issue a
6547 message identical to the startup message, except that
6548 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6549 or <tt>Restarting</tt> respectively.
6553 For example, stopping the printer daemon will look like
6555 <example compact="compact">
6556 Stopping printer spooler: lpd.
6562 <p>When something is executed</p>
6565 There are several examples where you have to run a
6566 program at system startup or shutdown to perform a
6567 specific task, for example, setting the system's clock
6568 using <prgn>netdate</prgn> or killing all processes
6569 when the system shuts down. Your message should look
6571 <example compact="compact">
6572 Doing something very useful...done.
6574 You should print the <tt>done.</tt> immediately after
6575 the job has been completed, so that the user is
6576 informed why they have to wait. You can get this
6578 <example compact="compact">
6579 echo -n "Doing something very useful..."
6588 <p>When the configuration is reloaded</p>
6591 When a daemon is forced to reload its configuration
6592 files you should use the following format:
6593 <example compact="compact">
6594 Reloading <var>description</var> configuration...done.
6596 where <var>description</var> is the same as in the
6597 daemon starting message.
6605 <heading>Cron jobs</heading>
6608 Packages must not modify the configuration file
6609 <file>/etc/crontab</file>, and they must not modify the files in
6610 <file>/var/spool/cron/crontabs</file>.</p>
6613 If a package wants to install a job that has to be executed
6614 via cron, it should place a file with the name of the
6615 package in one or more of the following directories:
6616 <example compact="compact">
6622 As these directory names imply, the files within them are
6623 executed on an hourly, daily, weekly, or monthly basis,
6624 respectively. The exact times are listed in
6625 <file>/etc/crontab</file>.</p>
6628 All files installed in any of these directories must be
6629 scripts (e.g., shell scripts or Perl scripts) so that they
6630 can easily be modified by the local system administrator.
6631 In addition, they must be treated as configuration files.
6635 If a certain job has to be executed at some other frequency or
6636 at a specific time, the package should install a file
6637 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6638 same syntax as <file>/etc/crontab</file> and is processed by
6639 <prgn>cron</prgn> automatically. The file must also be
6640 treated as a configuration file. (Note that entries in the
6641 <file>/etc/cron.d</file> directory are not handled by
6642 <prgn>anacron</prgn>. Thus, you should only use this
6643 directory for jobs which may be skipped if the system is not
6646 Unlike <file>crontab</file> files described in the IEEE Std
6647 1003.1-2008 (POSIX.1) available from
6648 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6649 name="The Open Group">, the files in
6650 <file>/etc/cron.d</file> and the file
6651 <file>/etc/crontab</file> have seven fields; namely:
6653 <item>Minute [0,59]</item>
6654 <item>Hour [0,23]</item>
6655 <item>Day of the month [1,31]</item>
6656 <item>Month of the year [1,12]</item>
6657 <item>Day of the week ([0,6] with 0=Sunday)</item>
6658 <item>Username</item>
6659 <item>Command to be run</item>
6661 Ranges of numbers are allowed. Ranges are two numbers
6662 separated with a hyphen. The specified range is inclusive.
6663 Lists are allowed. A list is a set of numbers (or ranges)
6664 separated by commas. Step values can be used in conjunction
6669 The scripts or <tt>crontab</tt> entries in these directories should
6670 check if all necessary programs are installed before they
6671 try to execute them. Otherwise, problems will arise when a
6672 package was removed but not purged since configuration files
6673 are kept on the system in this situation.
6677 Any <tt>cron</tt> daemon must provide
6678 <file>/usr/bin/crontab</file> and support normal
6679 <tt>crontab</tt> entries as specified in POSIX. The daemon
6680 must also support names for days and months, ranges, and
6681 step values. It has to support <file>/etc/crontab</file>,
6682 and correctly execute the scripts in
6683 <file>/etc/cron.d</file>. The daemon must also correctly
6685 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6690 <heading>Menus</heading>
6693 The Debian <tt>menu</tt> package provides a standard
6694 interface between packages providing applications and
6695 <em>menu programs</em> (either X window managers or
6696 text-based menu programs such as <prgn>pdmenu</prgn>).
6700 All packages that provide applications that need not be
6701 passed any special command line arguments for normal
6702 operation should register a menu entry for those
6703 applications, so that users of the <tt>menu</tt> package
6704 will automatically get menu entries in their window
6705 managers, as well in shells like <tt>pdmenu</tt>.
6709 Menu entries should follow the current menu policy.
6713 The menu policy can be found in the <tt>menu-policy</tt>
6714 files in the <tt>debian-policy</tt> package.
6715 It is also available from the Debian web mirrors at
6716 <tt><url name="/doc/packaging-manuals/menu-policy/"
6717 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6721 Please also refer to the <em>Debian Menu System</em>
6722 documentation that comes with the <package>menu</package>
6723 package for information about how to register your
6729 <heading>Multimedia handlers</heading>
6732 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6733 is a mechanism for encoding files and data streams and
6734 providing meta-information about them, in particular their
6735 type (e.g. audio or video) and format (e.g. PNG, HTML,
6740 Registration of MIME type handlers allows programs like mail
6741 user agents and web browsers to invoke these handlers to
6742 view, edit or display MIME types they don't support directly.
6746 Packages which provide the ability to view/show/play,
6747 compose, edit or print MIME types should register themselves
6748 as such following the current MIME support policy.
6752 The MIME support policy can be found in the <tt>mime-policy</tt>
6753 files in the <tt>debian-policy</tt> package.
6754 It is also available from the Debian web mirrors at
6755 <tt><url name="/doc/packaging-manuals/mime-policy/"
6756 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6762 <heading>Keyboard configuration</heading>
6765 To achieve a consistent keyboard configuration so that all
6766 applications interpret a keyboard event the same way, all
6767 programs in the Debian distribution must be configured to
6768 comply with the following guidelines.
6772 The following keys must have the specified interpretations:
6775 <tag><tt><--</tt></tag>
6776 <item>delete the character to the left of the cursor</item>
6778 <tag><tt>Delete</tt></tag>
6779 <item>delete the character to the right of the cursor</item>
6781 <tag><tt>Control+H</tt></tag>
6782 <item>emacs: the help prefix</item>
6785 The interpretation of any keyboard events should be
6786 independent of the terminal that is used, be it a virtual
6787 console, an X terminal emulator, an rlogin/telnet session,
6792 The following list explains how the different programs
6793 should be set up to achieve this:
6799 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6803 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6807 X translations are set up to make
6808 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6809 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6810 is the vt220 escape code for the "delete character"
6811 key). This must be done by loading the X resources
6812 using <prgn>xrdb</prgn> on all local X displays, not
6813 using the application defaults, so that the
6814 translation resources used correspond to the
6815 <prgn>xmodmap</prgn> settings.
6819 The Linux console is configured to make
6820 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6821 generate <tt>ESC [ 3 ~</tt>.
6825 X applications are configured so that <tt><</tt>
6826 deletes left, and <tt>Delete</tt> deletes right. Motif
6827 applications already work like this.
6831 Terminals should have <tt>stty erase ^?</tt> .
6835 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6836 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6837 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6841 Emacs is programmed to map <tt>KB_Backspace</tt> or
6842 the <tt>stty erase</tt> character to
6843 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6844 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6845 <tt>^H</tt> to <tt>help</tt> as always.
6849 Other applications use the <tt>stty erase</tt>
6850 character and <tt>kdch1</tt> for the two delete keys,
6851 with ASCII DEL being "delete previous character" and
6852 <tt>kdch1</tt> being "delete character under
6860 This will solve the problem except for the following
6867 Some terminals have a <tt><--</tt> key that cannot
6868 be made to produce anything except <tt>^H</tt>. On
6869 these terminals Emacs help will be unavailable on
6870 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6871 character takes precedence in Emacs, and has been set
6872 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6873 available) can be used instead.
6877 Some operating systems use <tt>^H</tt> for <tt>stty
6878 erase</tt>. However, modern telnet versions and all
6879 rlogin versions propagate <tt>stty</tt> settings, and
6880 almost all UNIX versions honour <tt>stty erase</tt>.
6881 Where the <tt>stty</tt> settings are not propagated
6882 correctly, things can be made to work by using
6883 <tt>stty</tt> manually.
6887 Some systems (including previous Debian versions) use
6888 <prgn>xmodmap</prgn> to arrange for both
6889 <tt><--</tt> and <tt>Delete</tt> to generate
6890 <tt>KB_Delete</tt>. We can change the behavior of
6891 their X clients using the same X resources that we use
6892 to do it for our own clients, or configure our clients
6893 using their resources when things are the other way
6894 around. On displays configured like this
6895 <tt>Delete</tt> will not work, but <tt><--</tt>
6900 Some operating systems have different <tt>kdch1</tt>
6901 settings in their <tt>terminfo</tt> database for
6902 <tt>xterm</tt> and others. On these systems the
6903 <tt>Delete</tt> key will not work correctly when you
6904 log in from a system conforming to our policy, but
6905 <tt><--</tt> will.
6912 <heading>Environment variables</heading>
6915 A program must not depend on environment variables to get
6916 reasonable defaults. (That's because these environment
6917 variables would have to be set in a system-wide
6918 configuration file like <file>/etc/profile</file>, which is not
6919 supported by all shells.)
6923 If a program usually depends on environment variables for its
6924 configuration, the program should be changed to fall back to
6925 a reasonable default configuration if these environment
6926 variables are not present. If this cannot be done easily
6927 (e.g., if the source code of a non-free program is not
6928 available), the program must be replaced by a small
6929 "wrapper" shell script which sets the environment variables
6930 if they are not already defined, and calls the original program.
6934 Here is an example of a wrapper script for this purpose:
6936 <example compact="compact">
6938 BAR=${BAR:-/var/lib/fubar}
6940 exec /usr/lib/foo/foo "$@"
6945 Furthermore, as <file>/etc/profile</file> is a configuration
6946 file of the <prgn>base-files</prgn> package, other packages must
6947 not put any environment variables or other commands into that
6952 <sect id="doc-base">
6953 <heading>Registering Documents using doc-base</heading>
6956 The <package>doc-base</package> package implements a
6957 flexible mechanism for handling and presenting
6958 documentation. The recommended practice is for every Debian
6959 package that provides online documentation (other than just
6960 manual pages) to register these documents with
6961 <package>doc-base</package> by installing a
6962 <package>doc-base</package> control file via the
6963 <prgn/install-docs/ script at installation time and
6964 de-register the manuals again when the package is removed.
6967 Please refer to the documentation that comes with the
6968 <package>doc-base</package> package for information and
6977 <heading>Files</heading>
6980 <heading>Binaries</heading>
6983 Two different packages must not install programs with
6984 different functionality but with the same filenames. (The
6985 case of two programs having the same functionality but
6986 different implementations is handled via "alternatives" or
6987 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6988 <ref id="conflicts"> respectively.) If this case happens,
6989 one of the programs must be renamed. The maintainers should
6990 report this to the <tt>debian-devel</tt> mailing list and
6991 try to find a consensus about which program will have to be
6992 renamed. If a consensus cannot be reached, <em>both</em>
6993 programs must be renamed.
6997 By default, when a package is being built, any binaries
6998 created should include debugging information, as well as
6999 being compiled with optimization. You should also turn on
7000 as many reasonable compilation warnings as possible; this
7001 makes life easier for porters, who can then look at build
7002 logs for possible problems. For the C programming language,
7003 this means the following compilation parameters should be
7005 <example compact="compact">
7007 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7009 INSTALL = install -s # (or use strip on the files in debian/tmp)
7014 Note that by default all installed binaries should be stripped,
7015 either by using the <tt>-s</tt> flag to
7016 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7017 the binaries after they have been copied into
7018 <file>debian/tmp</file> but before the tree is made into a
7023 Although binaries in the build tree should be compiled with
7024 debugging information by default, it can often be difficult to
7025 debug programs if they are also subjected to compiler
7026 optimization. For this reason, it is recommended to support the
7027 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7028 (see <ref id="debianrules-options">). This variable can contain
7029 several flags to change how a package is compiled and built.
7033 It is up to the package maintainer to decide what
7034 compilation options are best for the package. Certain
7035 binaries (such as computationally-intensive programs) will
7036 function better with certain flags (<tt>-O3</tt>, for
7037 example); feel free to use them. Please use good judgment
7038 here. Don't use flags for the sake of it; only use them
7039 if there is good reason to do so. Feel free to override
7040 the upstream author's ideas about which compilation
7041 options are best: they are often inappropriate for our
7047 <sect id="libraries">
7048 <heading>Libraries</heading>
7051 If the package is <strong>architecture: any</strong>, then
7052 the shared library compilation and linking flags must have
7053 <tt>-fPIC</tt>, or the package shall not build on some of
7054 the supported architectures<footnote>
7056 If you are using GCC, <tt>-fPIC</tt> produces code with
7057 relocatable position independent code, which is required for
7058 most architectures to create a shared library, with i386 and
7059 perhaps some others where non position independent code is
7060 permitted in a shared library.
7063 Position independent code may have a performance penalty,
7064 especially on <tt>i386</tt>. However, in most cases the
7065 speed penalty must be measured against the memory wasted on
7066 the few architectures where non position independent code is
7069 </footnote>. Any exception to this rule must be discussed on
7070 the mailing list <em>debian-devel@lists.debian.org</em>, and
7071 a rough consensus obtained. The reasons for not compiling
7072 with <tt>-fPIC</tt> flag must be recorded in the file
7073 <tt>README.Debian</tt>, and care must be taken to either
7074 restrict the architecture or arrange for <tt>-fPIC</tt> to
7075 be used on architectures where it is required.<footnote>
7077 Some of the reasons why this might be required is if the
7078 library contains hand crafted assembly code that is not
7079 relocatable, the speed penalty is excessive for compute
7080 intensive libs, and similar reasons.
7085 As to the static libraries, the common case is not to have
7086 relocatable code, since there is no benefit, unless in specific
7087 cases; therefore the static version must not be compiled
7088 with the <tt>-fPIC</tt> flag. Any exception to this rule
7089 should be discussed on the mailing list
7090 <em>debian-devel@lists.debian.org</em>, and the reasons for
7091 compiling with the <tt>-fPIC</tt> flag must be recorded in
7092 the file <tt>README.Debian</tt>. <footnote>
7094 Some of the reasons for linking static libraries with
7095 the <tt>-fPIC</tt> flag are if, for example, one needs a
7096 Perl API for a library that is under rapid development,
7097 and has an unstable API, so shared libraries are
7098 pointless at this phase of the library's development. In
7099 that case, since Perl needs a library with relocatable
7100 code, it may make sense to create a static library with
7101 relocatable code. Another reason cited is if you are
7102 distilling various libraries into a common shared
7103 library, like <tt>mklibs</tt> does in the Debian
7109 In other words, if both a shared and a static library is
7110 being built, each source unit (<tt>*.c</tt>, for example,
7111 for C files) will need to be compiled twice, for the normal
7115 You must specify the gcc option <tt>-D_REENTRANT</tt>
7116 when building a library (either static or shared) to make
7117 the library compatible with LinuxThreads.
7121 Although not enforced by the build tools, shared libraries
7122 must be linked against all libraries that they use symbols from
7123 in the same way that binaries are. This ensures the correct
7124 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7125 system and guarantees that all libraries can be safely opened
7126 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7127 option <tt>-Wl,-z,defs</tt> when building a shared library.
7128 Since this option enforces symbol resolution at build time,
7129 a missing library reference will be caught early as a fatal
7134 All installed shared libraries should be stripped with
7135 <example compact="compact">
7136 strip --strip-unneeded <var>your-lib</var>
7138 (The option <tt>--strip-unneeded</tt> makes
7139 <prgn>strip</prgn> remove only the symbols which aren't
7140 needed for relocation processing.) Shared libraries can
7141 function perfectly well when stripped, since the symbols for
7142 dynamic linking are in a separate part of the ELF object
7144 You might also want to use the options
7145 <tt>--remove-section=.comment</tt> and
7146 <tt>--remove-section=.note</tt> on both shared libraries
7147 and executables, and <tt>--strip-debug</tt> on static
7153 Note that under some circumstances it may be useful to
7154 install a shared library unstripped, for example when
7155 building a separate package to support debugging.
7159 Shared object files (often <file>.so</file> files) that are not
7160 public libraries, that is, they are not meant to be linked
7161 to by third party executables (binaries of other packages),
7162 should be installed in subdirectories of the
7163 <file>/usr/lib</file> directory. Such files are exempt from the
7164 rules that govern ordinary shared libraries, except that
7165 they must not be installed executable and should be
7167 A common example are the so-called "plug-ins",
7168 internal shared objects that are dynamically loaded by
7169 programs using <manref name="dlopen" section="3">.
7174 An ever increasing number of packages are using
7175 <prgn>libtool</prgn> to do their linking. The latest GNU
7176 libtools (>= 1.3a) can take advantage of the metadata in the
7177 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7178 files). The main advantage of <prgn>libtool</prgn>'s
7179 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7180 store and subsequently access metadata with respect to the
7181 libraries it builds. <prgn>libtool</prgn> will search for
7182 those files, which contain a lot of useful information about
7183 a library (such as library dependency information for static
7184 linking). Also, they're <em>essential</em> for programs
7185 using <tt>libltdl</tt>.<footnote>
7186 Although <prgn>libtool</prgn> is fully capable of
7187 linking against shared libraries which don't have
7188 <tt>.la</tt> files, as it is a mere shell script it can
7189 add considerably to the build time of a
7190 <prgn>libtool</prgn>-using package if that shell script
7191 has to derive all this information from first principles
7192 for each library every time it is linked. With the
7193 advent of <prgn>libtool</prgn> version 1.4 (and to a
7194 lesser extent <prgn>libtool</prgn> version 1.3), the
7195 <file>.la</file> files also store information about
7196 inter-library dependencies which cannot necessarily be
7197 derived after the <file>.la</file> file is deleted.
7202 Packages that use <prgn>libtool</prgn> to create shared
7203 libraries should include the <file>.la</file> files in the
7204 <tt>-dev</tt> package, unless the package relies on
7205 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7206 the <tt>.la</tt> files must go in the run-time library
7211 You must make sure that you use only released versions of
7212 shared libraries to build your packages; otherwise other
7213 users will not be able to run your binaries
7214 properly. Producing source packages that depend on
7215 unreleased compilers is also usually a bad
7222 <heading>Shared libraries</heading>
7224 This section has moved to <ref id="sharedlibs">.
7230 <heading>Scripts</heading>
7233 All command scripts, including the package maintainer
7234 scripts inside the package and used by <prgn>dpkg</prgn>,
7235 should have a <tt>#!</tt> line naming the shell to be used
7240 In the case of Perl scripts this should be
7241 <tt>#!/usr/bin/perl</tt>.
7245 When scripts are installed into a directory in the system
7246 PATH, the script name should not include an extension such
7247 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7248 language currently used to implement it.
7251 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7252 <file>init.d</file> scripts should almost certainly start
7253 with <tt>set -e</tt> so that errors are detected.
7254 <file>init.d</file> scripts are something of a special case, due
7255 to how frequently they need to call commands that are allowed to
7256 fail, and it may instead be easier to check the exit status of
7257 commands directly. See <ref id="writing-init"> for more
7258 information about writing <file>init.d</file> scripts.
7261 Every script should use <tt>set -e</tt> or check the exit status
7262 of <em>every</em> command.
7265 Scripts may assume that <file>/bin/sh</file> implements the
7266 SUSv3 Shell Command Language<footnote>
7267 Single UNIX Specification, version 3, which is also IEEE
7268 1003.1-2004 (POSIX), and is available on the World Wide Web
7269 from <url id="http://www.unix.org/version3/online.html"
7270 name="The Open Group"> after free
7271 registration.</footnote>
7272 plus the following additional features not mandated by
7274 These features are in widespread use in the Linux community
7275 and are implemented in all of bash, dash, and ksh, the most
7276 common shells users may wish to use as <file>/bin/sh</file>.
7279 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7280 must not generate a newline.</item>
7281 <item><tt>test</tt>, if implemented as a shell built-in, must
7282 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7284 <item><tt>local</tt> to create a scoped variable must be
7285 supported, including listing multiple variables in a single
7286 local command and assigning a value to a variable at the
7287 same time as localizing it. <tt>local</tt> may or
7288 may not preserve the variable value from an outer scope if
7289 no assignment is present. Uses such as:
7293 # ... use a, b, c, d ...
7296 must be supported and must set the value of <tt>c</tt> to
7300 If a shell script requires non-SUSv3 features from the shell
7301 interpreter other than those listed above, the appropriate shell
7302 must be specified in the first line of the script (e.g.,
7303 <tt>#!/bin/bash</tt>) and the package must depend on the package
7304 providing the shell (unless the shell package is marked
7305 "Essential", as in the case of <prgn>bash</prgn>).
7309 You may wish to restrict your script to SUSv3 features plus the
7310 above set when possible so that it may use <file>/bin/sh</file>
7311 as its interpreter. If your script works with <prgn>dash</prgn>
7312 (originally called <prgn>ash</prgn>), it probably complies with
7313 the above requirements, but if you are in doubt, use
7314 <file>/bin/bash</file>.
7318 Perl scripts should check for errors when making any
7319 system calls, including <tt>open</tt>, <tt>print</tt>,
7320 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7324 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7325 scripting languages. See <em>Csh Programming Considered
7326 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7327 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7328 If an upstream package comes with <prgn>csh</prgn> scripts
7329 then you must make sure that they start with
7330 <tt>#!/bin/csh</tt> and make your package depend on the
7331 <prgn>c-shell</prgn> virtual package.
7335 Any scripts which create files in world-writeable
7336 directories (e.g., in <file>/tmp</file>) must use a
7337 mechanism which will fail atomically if a file with the same
7338 name already exists.
7342 The Debian base system provides the <prgn>tempfile</prgn>
7343 and <prgn>mktemp</prgn> utilities for use by scripts for
7350 <heading>Symbolic links</heading>
7353 In general, symbolic links within a top-level directory
7354 should be relative, and symbolic links pointing from one
7355 top-level directory into another should be absolute. (A
7356 top-level directory is a sub-directory of the root
7357 directory <file>/</file>.)
7361 In addition, symbolic links should be specified as short as
7362 possible, i.e., link targets like <file>foo/../bar</file> are
7367 Note that when creating a relative link using
7368 <prgn>ln</prgn> it is not necessary for the target of the
7369 link to exist relative to the working directory you're
7370 running <prgn>ln</prgn> from, nor is it necessary to change
7371 directory to the directory where the link is to be made.
7372 Simply include the string that should appear as the target
7373 of the link (this will be a pathname relative to the
7374 directory in which the link resides) as the first argument
7379 For example, in your <prgn>Makefile</prgn> or
7380 <file>debian/rules</file>, you can do things like:
7381 <example compact="compact">
7382 ln -fs gcc $(prefix)/bin/cc
7383 ln -fs gcc debian/tmp/usr/bin/cc
7384 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7385 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7390 A symbolic link pointing to a compressed file should always
7391 have the same file extension as the referenced file. (For
7392 example, if a file <file>foo.gz</file> is referenced by a
7393 symbolic link, the filename of the link has to end with
7394 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7399 <heading>Device files</heading>
7402 Packages must not include device files or named pipes in the
7407 If a package needs any special device files that are not
7408 included in the base system, it must call
7409 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7410 after notifying the user<footnote>
7411 This notification could be done via a (low-priority)
7412 debconf message, or an echo (printf) statement.
7417 Packages must not remove any device files in the
7418 <prgn>postrm</prgn> or any other script. This is left to the
7419 system administrator.
7423 Debian uses the serial devices
7424 <file>/dev/ttyS*</file>. Programs using the old
7425 <file>/dev/cu*</file> devices should be changed to use
7426 <file>/dev/ttyS*</file>.
7430 Named pipes needed by the package must be created in
7431 the <prgn>postinst</prgn> script<footnote>
7432 It's better to use <prgn>mkfifo</prgn> rather
7433 than <prgn>mknod</prgn> to create named pipes so that
7434 automated checks for packages incorrectly creating device
7435 files with <prgn>mknod</prgn> won't have false positives.
7436 </footnote> and removed in
7437 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7442 <sect id="config-files">
7443 <heading>Configuration files</heading>
7446 <heading>Definitions</heading>
7450 <tag>configuration file</tag>
7452 A file that affects the operation of a program, or
7453 provides site- or host-specific information, or
7454 otherwise customizes the behavior of a program.
7455 Typically, configuration files are intended to be
7456 modified by the system administrator (if needed or
7457 desired) to conform to local policy or to provide
7458 more useful site-specific behavior.
7461 <tag><tt>conffile</tt></tag>
7463 A file listed in a package's <tt>conffiles</tt>
7464 file, and is treated specially by <prgn>dpkg</prgn>
7465 (see <ref id="configdetails">).
7471 The distinction between these two is important; they are
7472 not interchangeable concepts. Almost all
7473 <tt>conffile</tt>s are configuration files, but many
7474 configuration files are not <tt>conffiles</tt>.
7478 As noted elsewhere, <file>/etc/init.d</file> scripts,
7479 <file>/etc/default</file> files, scripts installed in
7480 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7481 configuration installed in <file>/etc/cron.d</file> must be
7482 treated as configuration files. In general, any script that
7483 embeds configuration information is de-facto a configuration
7484 file and should be treated as such.
7489 <heading>Location</heading>
7492 Any configuration files created or used by your package
7493 must reside in <file>/etc</file>. If there are several,
7494 consider creating a subdirectory of <file>/etc</file>
7495 named after your package.
7499 If your package creates or uses configuration files
7500 outside of <file>/etc</file>, and it is not feasible to modify
7501 the package to use <file>/etc</file> directly, put the files
7502 in <file>/etc</file> and create symbolic links to those files
7503 from the location that the package requires.
7508 <heading>Behavior</heading>
7511 Configuration file handling must conform to the following
7513 <list compact="compact">
7515 local changes must be preserved during a package
7519 configuration files must be preserved when the
7520 package is removed, and only deleted when the
7527 The easy way to achieve this behavior is to make the
7528 configuration file a <tt>conffile</tt>. This is
7529 appropriate only if it is possible to distribute a default
7530 version that will work for most installations, although
7531 some system administrators may choose to modify it. This
7532 implies that the default version will be part of the
7533 package distribution, and must not be modified by the
7534 maintainer scripts during installation (or at any other
7539 In order to ensure that local changes are preserved
7540 correctly, no package may contain or make hard links to
7541 conffiles.<footnote>
7542 Rationale: There are two problems with hard links.
7543 The first is that some editors break the link while
7544 editing one of the files, so that the two files may
7545 unwittingly become unlinked and different. The second
7546 is that <prgn>dpkg</prgn> might break the hard link
7547 while upgrading <tt>conffile</tt>s.
7552 The other way to do it is via the maintainer scripts. In
7553 this case, the configuration file must not be listed as a
7554 <tt>conffile</tt> and must not be part of the package
7555 distribution. If the existence of a file is required for
7556 the package to be sensibly configured it is the
7557 responsibility of the package maintainer to provide
7558 maintainer scripts which correctly create, update and
7559 maintain the file and remove it on purge. (See <ref
7560 id="maintainerscripts"> for more information.) These
7561 scripts must be idempotent (i.e., must work correctly if
7562 <prgn>dpkg</prgn> needs to re-run them due to errors
7563 during installation or removal), must cope with all the
7564 variety of ways <prgn>dpkg</prgn> can call maintainer
7565 scripts, must not overwrite or otherwise mangle the user's
7566 configuration without asking, must not ask unnecessary
7567 questions (particularly during upgrades), and must
7568 otherwise be good citizens.
7572 The scripts are not required to configure every possible
7573 option for the package, but only those necessary to get
7574 the package running on a given system. Ideally the
7575 sysadmin should not have to do any configuration other
7576 than that done (semi-)automatically by the
7577 <prgn>postinst</prgn> script.
7581 A common practice is to create a script called
7582 <file><var>package</var>-configure</file> and have the
7583 package's <prgn>postinst</prgn> call it if and only if the
7584 configuration file does not already exist. In certain
7585 cases it is useful for there to be an example or template
7586 file which the maintainer scripts use. Such files should
7587 be in <file>/usr/share/<var>package</var></file> or
7588 <file>/usr/lib/<var>package</var></file> (depending on whether
7589 they are architecture-independent or not). There should
7590 be symbolic links to them from
7591 <file>/usr/share/doc/<var>package</var>/examples</file> if
7592 they are examples, and should be perfectly ordinary
7593 <prgn>dpkg</prgn>-handled files (<em>not</em>
7594 configuration files).
7598 These two styles of configuration file handling must
7599 not be mixed, for that way lies madness:
7600 <prgn>dpkg</prgn> will ask about overwriting the file
7601 every time the package is upgraded.
7606 <heading>Sharing configuration files</heading>
7609 Packages which specify the same file as a
7610 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7611 with each other. (This is an instance of the general rule
7612 about not sharing files. Note that neither alternatives
7613 nor diversions are likely to be appropriate in this case;
7614 in particular, <prgn>dpkg</prgn> does not handle diverted
7615 <tt>conffile</tt>s well.)
7619 The maintainer scripts must not alter a <tt>conffile</tt>
7620 of <em>any</em> package, including the one the scripts
7625 If two or more packages use the same configuration file
7626 and it is reasonable for both to be installed at the same
7627 time, one of these packages must be defined as
7628 <em>owner</em> of the configuration file, i.e., it will be
7629 the package which handles that file as a configuration
7630 file. Other packages that use the configuration file must
7631 depend on the owning package if they require the
7632 configuration file to operate. If the other package will
7633 use the configuration file if present, but is capable of
7634 operating without it, no dependency need be declared.
7638 If it is desirable for two or more related packages to
7639 share a configuration file <em>and</em> for all of the
7640 related packages to be able to modify that configuration
7641 file, then the following should be done:
7642 <enumlist compact="compact">
7644 One of the related packages (the "owning" package)
7645 will manage the configuration file with maintainer
7646 scripts as described in the previous section.
7649 The owning package should also provide a program
7650 that the other packages may use to modify the
7654 The related packages must use the provided program
7655 to make any desired modifications to the
7656 configuration file. They should either depend on
7657 the core package to guarantee that the configuration
7658 modifier program is available or accept gracefully
7659 that they cannot modify the configuration file if it
7660 is not. (This is in addition to the fact that the
7661 configuration file may not even be present in the
7668 Sometimes it's appropriate to create a new package which
7669 provides the basic infrastructure for the other packages
7670 and which manages the shared configuration files. (The
7671 <tt>sgml-base</tt> package is a good example.)
7676 <heading>User configuration files ("dotfiles")</heading>
7679 The files in <file>/etc/skel</file> will automatically be
7680 copied into new user accounts by <prgn>adduser</prgn>.
7681 No other program should reference the files in
7682 <file>/etc/skel</file>.
7686 Therefore, if a program needs a dotfile to exist in
7687 advance in <file>$HOME</file> to work sensibly, that dotfile
7688 should be installed in <file>/etc/skel</file> and treated as a
7693 However, programs that require dotfiles in order to
7694 operate sensibly are a bad thing, unless they do create
7695 the dotfiles themselves automatically.
7699 Furthermore, programs should be configured by the Debian
7700 default installation to behave as closely to the upstream
7701 default behavior as possible.
7705 Therefore, if a program in a Debian package needs to be
7706 configured in some way in order to operate sensibly, that
7707 should be done using a site-wide configuration file placed
7708 in <file>/etc</file>. Only if the program doesn't support a
7709 site-wide default configuration and the package maintainer
7710 doesn't have time to add it may a default per-user file be
7711 placed in <file>/etc/skel</file>.
7715 <file>/etc/skel</file> should be as empty as we can make it.
7716 This is particularly true because there is no easy (or
7717 necessarily desirable) mechanism for ensuring that the
7718 appropriate dotfiles are copied into the accounts of
7719 existing users when a package is installed.
7725 <heading>Log files</heading>
7727 Log files should usually be named
7728 <file>/var/log/<var>package</var>.log</file>. If you have many
7729 log files, or need a separate directory for permission
7730 reasons (<file>/var/log</file> is writable only by
7731 <file>root</file>), you should usually create a directory named
7732 <file>/var/log/<var>package</var></file> and place your log
7737 Log files must be rotated occasionally so that they don't
7738 grow indefinitely; the best way to do this is to drop a log
7739 rotation configuration file into the directory
7740 <file>/etc/logrotate.d</file> and use the facilities provided by
7741 logrotate.<footnote>
7743 The traditional approach to log files has been to set up
7744 <em>ad hoc</em> log rotation schemes using simple shell
7745 scripts and cron. While this approach is highly
7746 customizable, it requires quite a lot of sysadmin work.
7747 Even though the original Debian system helped a little
7748 by automatically installing a system which can be used
7749 as a template, this was deemed not enough.
7753 The use of <prgn>logrotate</prgn>, a program developed
7754 by Red Hat, is better, as it centralizes log management.
7755 It has both a configuration file
7756 (<file>/etc/logrotate.conf</file>) and a directory where
7757 packages can drop their individual log rotation
7758 configurations (<file>/etc/logrotate.d</file>).
7761 Here is a good example for a logrotate config
7762 file (for more information see <manref name="logrotate"
7764 <example compact="compact">
7765 /var/log/foo/*.log {
7770 /etc/init.d/foo force-reload
7774 This rotates all files under <file>/var/log/foo</file>, saves 12
7775 compressed generations, and forces the daemon to reload its
7776 configuration information after the log rotation.
7780 Log files should be removed when the package is
7781 purged (but not when it is only removed). This should be
7782 done by the <prgn>postrm</prgn> script when it is called
7783 with the argument <tt>purge</tt> (see <ref
7784 id="removedetails">).
7789 <heading>Permissions and owners</heading>
7792 The rules in this section are guidelines for general use.
7793 If necessary you may deviate from the details below.
7794 However, if you do so you must make sure that what is done
7795 is secure and you should try to be as consistent as possible
7796 with the rest of the system. You should probably also
7797 discuss it on <prgn>debian-devel</prgn> first.
7801 Files should be owned by <tt>root:root</tt>, and made
7802 writable only by the owner and universally readable (and
7803 executable, if appropriate), that is mode 644 or 755.
7807 Directories should be mode 755 or (for group-writability)
7808 mode 2775. The ownership of the directory should be
7809 consistent with its mode: if a directory is mode 2775, it
7810 should be owned by the group that needs write access to
7813 When a package is upgraded, and the owner or permissions
7814 of a file included in the package has changed, dpkg
7815 arranges for the ownership and permissions to be
7816 correctly set upon installation. However, this does not
7817 extend to directories; the permissions and ownership of
7818 directories already on the system does not change on
7819 install or upgrade of packages. This makes sense, since
7820 otherwise common directories like <tt>/usr</tt> would
7821 always be in flux. To correctly change permissions of a
7822 directory the package owns, explicit action is required,
7823 usually in the <tt>postinst</tt> script. Care must be
7824 taken to handle downgrades as well, in that case.
7831 Setuid and setgid executables should be mode 4755 or 2755
7832 respectively, and owned by the appropriate user or group.
7833 They should not be made unreadable (modes like 4711 or
7834 2711 or even 4111); doing so achieves no extra security,
7835 because anyone can find the binary in the freely available
7836 Debian package; it is merely inconvenient. For the same
7837 reason you should not restrict read or execute permissions
7838 on non-set-id executables.
7842 Some setuid programs need to be restricted to particular
7843 sets of users, using file permissions. In this case they
7844 should be owned by the uid to which they are set-id, and by
7845 the group which should be allowed to execute them. They
7846 should have mode 4754; again there is no point in making
7847 them unreadable to those users who must not be allowed to
7852 It is possible to arrange that the system administrator can
7853 reconfigure the package to correspond to their local
7854 security policy by changing the permissions on a binary:
7855 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7856 described below.<footnote>
7857 Ordinary files installed by <prgn>dpkg</prgn> (as
7858 opposed to <tt>conffile</tt>s and other similar objects)
7859 normally have their permissions reset to the distributed
7860 permissions when the package is reinstalled. However,
7861 the use of <prgn>dpkg-statoverride</prgn> overrides this
7864 Another method you should consider is to create a group for
7865 people allowed to use the program(s) and make any setuid
7866 executables executable only by that group.
7870 If you need to create a new user or group for your package
7871 there are two possibilities. Firstly, you may need to
7872 make some files in the binary package be owned by this
7873 user or group, or you may need to compile the user or
7874 group id (rather than just the name) into the binary
7875 (though this latter should be avoided if possible, as in
7876 this case you need a statically allocated id).</p>
7879 If you need a statically allocated id, you must ask for a
7880 user or group id from the <tt>base-passwd</tt> maintainer,
7881 and must not release the package until you have been
7882 allocated one. Once you have been allocated one you must
7883 either make the package depend on a version of the
7884 <tt>base-passwd</tt> package with the id present in
7885 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7886 your package to create the user or group itself with the
7887 correct id (using <tt>adduser</tt>) in its
7888 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7889 the <prgn>postinst</prgn> is to be preferred if it is
7890 possible, otherwise a pre-dependency will be needed on the
7891 <tt>adduser</tt> package.)
7895 On the other hand, the program might be able to determine
7896 the uid or gid from the user or group name at runtime, so
7897 that a dynamically allocated id can be used. In this case
7898 you should choose an appropriate user or group name,
7899 discussing this on <prgn>debian-devel</prgn> and checking
7900 with the <package/base-passwd/ maintainer that it is unique and that
7901 they do not wish you to use a statically allocated id
7902 instead. When this has been checked you must arrange for
7903 your package to create the user or group if necessary using
7904 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7905 <prgn>postinst</prgn> script (again, the latter is to be
7906 preferred if it is possible).
7910 Note that changing the numeric value of an id associated
7911 with a name is very difficult, and involves searching the
7912 file system for all appropriate files. You need to think
7913 carefully whether a static or dynamic id is required, since
7914 changing your mind later will cause problems.
7917 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7919 This section is not intended as policy, but as a
7920 description of the use of <prgn>dpkg-statoverride</prgn>.
7924 If a system administrator wishes to have a file (or
7925 directory or other such thing) installed with owner and
7926 permissions different from those in the distributed Debian
7927 package, they can use the <prgn>dpkg-statoverride</prgn>
7928 program to instruct <prgn>dpkg</prgn> to use the different
7929 settings every time the file is installed. Thus the
7930 package maintainer should distribute the files with their
7931 normal permissions, and leave it for the system
7932 administrator to make any desired changes. For example, a
7933 daemon which is normally required to be setuid root, but
7934 in certain situations could be used without being setuid,
7935 should be installed setuid in the <tt>.deb</tt>. Then the
7936 local system administrator can change this if they wish.
7937 If there are two standard ways of doing it, the package
7938 maintainer can use <tt>debconf</tt> to find out the
7939 preference, and call <prgn>dpkg-statoverride</prgn> in the
7940 maintainer script if necessary to accommodate the system
7941 administrator's choice. Care must be taken during
7942 upgrades to not override an existing setting.
7946 Given the above, <prgn>dpkg-statoverride</prgn> is
7947 essentially a tool for system administrators and would not
7948 normally be needed in the maintainer scripts. There is
7949 one type of situation, though, where calls to
7950 <prgn>dpkg-statoverride</prgn> would be needed in the
7951 maintainer scripts, and that involves packages which use
7952 dynamically allocated user or group ids. In such a
7953 situation, something like the following idiom can be very
7954 helpful in the package's <prgn>postinst</prgn>, where
7955 <tt>sysuser</tt> is a dynamically allocated id:
7957 for i in /usr/bin/foo /usr/sbin/bar
7959 # only do something when no setting exists
7960 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7962 #include: debconf processing, question about foo and bar
7963 if [ "$RET" = "true" ] ; then
7964 dpkg-statoverride --update --add sysuser root 4755 $i
7969 The corresponding code to remove the override when the package
7972 for i in /usr/bin/foo /usr/sbin/bar
7974 if dpkg-statoverride --list $i >/dev/null 2>&1
7976 dpkg-statoverride --remove $i
7986 <chapt id="customized-programs">
7987 <heading>Customized programs</heading>
7989 <sect id="arch-spec">
7990 <heading>Architecture specification strings</heading>
7993 If a program needs to specify an <em>architecture specification
7994 string</em> in some place, it should select one of the strings
7995 provided by <tt>dpkg-architecture -L</tt>. The strings are in
7996 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
7997 part is sometimes elided, as when the OS is Linux.
8001 Note that we don't want to use
8002 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8003 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8004 since this would make our programs incompatible with other
8005 Linux distributions. We also don't use something like
8006 <tt><var>arch</var>-unknown-linux</tt>, since the
8007 <tt>unknown</tt> does not look very good.
8010 <sect1 id="arch-wildcard-spec">
8011 <heading>Architecture wildcards</heading>
8014 A package may specify an architecture wildcard. Architecture
8015 wildcards are in the format <tt>any</tt> (which matches every
8016 architecture), <tt><var>os</var></tt>-any, or
8017 any-<tt><var>cpu</var></tt>. <footnote>
8018 Internally, the package system normalizes the GNU triplets
8019 and the Debian arches into Debian arch triplets (which are
8020 kind of inverted GNU triplets), with the first component of
8021 the triplet representing the libc and ABI in use, and then
8022 does matching against those triplets. However, such
8023 triplets are an internal implementation detail that should
8024 not be used by packages directly. The libc and ABI portion
8025 is handled internally by the package system based on
8026 the <var>os</var> and <var>cpu</var>.
8033 <heading>Daemons</heading>
8036 The configuration files <file>/etc/services</file>,
8037 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8038 by the <prgn>netbase</prgn> package and must not be modified
8043 If a package requires a new entry in one of these files, the
8044 maintainer should get in contact with the
8045 <prgn>netbase</prgn> maintainer, who will add the entries
8046 and release a new version of the <prgn>netbase</prgn>
8051 The configuration file <file>/etc/inetd.conf</file> must not be
8052 modified by the package's scripts except via the
8053 <prgn>update-inetd</prgn> script or the
8054 <file>DebianNet.pm</file> Perl module. See their documentation
8055 for details on how to add entries.
8059 If a package wants to install an example entry into
8060 <file>/etc/inetd.conf</file>, the entry must be preceded with
8061 exactly one hash character (<tt>#</tt>). Such lines are
8062 treated as "commented out by user" by the
8063 <prgn>update-inetd</prgn> script and are not changed or
8064 activated during package updates.
8069 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8073 Some programs need to create pseudo-ttys. This should be done
8074 using Unix98 ptys if the C library supports it. The resulting
8075 program must not be installed setuid root, unless that
8076 is required for other functionality.
8080 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8081 <file>/var/log/lastlog</file> must be installed writable by
8082 group <tt>utmp</tt>. Programs which need to modify those
8083 files must be installed setgid <tt>utmp</tt>.
8088 <heading>Editors and pagers</heading>
8091 Some programs have the ability to launch an editor or pager
8092 program to edit or display a text document. Since there are
8093 lots of different editors and pagers available in the Debian
8094 distribution, the system administrator and each user should
8095 have the possibility to choose their preferred editor and
8100 In addition, every program should choose a good default
8101 editor/pager if none is selected by the user or system
8106 Thus, every program that launches an editor or pager must
8107 use the EDITOR or PAGER environment variable to determine
8108 the editor or pager the user wishes to use. If these
8109 variables are not set, the programs <file>/usr/bin/editor</file>
8110 and <file>/usr/bin/pager</file> should be used, respectively.
8114 These two files are managed through the <prgn>dpkg</prgn>
8115 "alternatives" mechanism. Thus every package providing an
8116 editor or pager must call the
8117 <prgn>update-alternatives</prgn> script to register these
8122 If it is very hard to adapt a program to make use of the
8123 EDITOR or PAGER variables, that program may be configured to
8124 use <file>/usr/bin/sensible-editor</file> and
8125 <file>/usr/bin/sensible-pager</file> as the editor or pager
8126 program respectively. These are two scripts provided in the
8127 <package>sensible-utils</package> package that check the EDITOR
8128 and PAGER variables and launch the appropriate program, and fall
8129 back to <file>/usr/bin/editor</file>
8130 and <file>/usr/bin/pager</file> if the variable is not set.
8134 A program may also use the VISUAL environment variable to
8135 determine the user's choice of editor. If it exists, it
8136 should take precedence over EDITOR. This is in fact what
8137 <file>/usr/bin/sensible-editor</file> does.
8141 It is not required for a package to depend on
8142 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8143 package to provide such virtual packages.<footnote>
8144 The Debian base system already provides an editor and a
8150 <sect id="web-appl">
8151 <heading>Web servers and applications</heading>
8154 This section describes the locations and URLs that should
8155 be used by all web servers and web applications in the
8162 Cgi-bin executable files are installed in the
8164 <example compact="compact">
8165 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8167 and should be referred to as
8168 <example compact="compact">
8169 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8175 <p>Access to HTML documents</p>
8178 HTML documents for a package are stored in
8179 <file>/usr/share/doc/<var>package</var></file>
8180 and can be referred to as
8181 <example compact="compact">
8182 http://localhost/doc/<var>package</var>/<var>filename</var>
8187 The web server should restrict access to the document
8188 tree so that only clients on the same host can read
8189 the documents. If the web server does not support such
8190 access controls, then it should not provide access at
8191 all, or ask about providing access during installation.
8196 <p>Access to images</p>
8198 It is recommended that images for a package be stored
8199 in <tt>/usr/share/images/<var>package</var></tt> and
8200 may be referred to through an alias <tt>/images/</tt>
8203 http://localhost/images/<package>/<filename>
8210 <p>Web Document Root</p>
8213 Web Applications should try to avoid storing files in
8214 the Web Document Root. Instead they should use the
8215 /usr/share/doc/<var>package</var> directory for
8216 documents and register the Web Application via the
8217 <package>doc-base</package> package. If access to the
8218 web document root is unavoidable then use
8219 <example compact="compact">
8222 as the Document Root. This might be just a symbolic
8223 link to the location where the system administrator
8224 has put the real document root.
8227 <item><p>Providing httpd and/or httpd-cgi</p>
8229 All web servers should provide the virtual package
8230 <tt>httpd</tt>. If a web server has CGI support it should
8231 provide <tt>httpd-cgi</tt> additionally.
8234 All web applications which do not contain CGI scripts should
8235 depend on <tt>httpd</tt>, all those web applications which
8236 <tt>do</tt> contain CGI scripts, should depend on
8244 <sect id="mail-transport-agents">
8245 <heading>Mail transport, delivery and user agents</heading>
8248 Debian packages which process electronic mail, whether mail
8249 user agents (MUAs) or mail transport agents (MTAs), must
8250 ensure that they are compatible with the configuration
8251 decisions below. Failure to do this may result in lost
8252 mail, broken <tt>From:</tt> lines, and other serious brain
8257 The mail spool is <file>/var/mail</file> and the interface to
8258 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8259 the FHS). On older systems, the mail spool may be
8260 physically located in <file>/var/spool/mail</file>, but all
8261 access to the mail spool should be via the
8262 <file>/var/mail</file> symlink. The mail spool is part of the
8263 base system and not part of the MTA package.
8267 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8268 programs (such as IMAP daemons) must lock the mailbox in an
8269 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8270 be combined with dot locking. To avoid deadlocks, a program
8271 should use <tt>fcntl()</tt> first and dot locking after
8272 this, or alternatively implement the two locking methods in
8273 a non blocking way<footnote>
8274 If it is not possible to establish both locks, the
8275 system shouldn't wait for the second lock to be
8276 established, but remove the first lock, wait a (random)
8277 time, and start over locking again.
8278 </footnote>. Using the functions <tt>maillock</tt> and
8279 <tt>mailunlock</tt> provided by the
8280 <tt>liblockfile*</tt><footnote>
8281 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8282 to use these functions.
8283 </footnote> packages is the recommended way to realize this.
8287 Mailboxes are generally either mode 600 and owned by
8288 <var>user</var> or mode 660 and owned by
8289 <tt><var>user</var>:mail</tt><footnote>
8290 There are two traditional permission schemes for mail spools:
8291 mode 600 with all mail delivery done by processes running as
8292 the destination user, or mode 660 and owned by group mail with
8293 mail delivery done by a process running as a system user in
8294 group mail. Historically, Debian required mode 660 mail
8295 spools to enable the latter model, but that model has become
8296 increasingly uncommon and the principle of least privilege
8297 indicates that mail systems that use the first model should
8298 use permissions of 600. If delivery to programs is permitted,
8299 it's easier to keep the mail system secure if the delivery
8300 agent runs as the destination user. Debian Policy therefore
8301 permits either scheme.
8302 </footnote>. The local system administrator may choose a
8303 different permission scheme; packages should not make
8304 assumptions about the permission and ownership of mailboxes
8305 unless required (such as when creating a new mailbox). A MUA
8306 may remove a mailbox (unless it has nonstandard permissions) in
8307 which case the MTA or another MUA must recreate it if needed.
8311 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8312 be setgid mail to do the locking mentioned above (and
8313 must obviously avoid accessing other users' mailboxes
8314 using this privilege).</p>
8317 <file>/etc/aliases</file> is the source file for the system mail
8318 aliases (e.g., postmaster, usenet, etc.), it is the one
8319 which the sysadmin and <prgn>postinst</prgn> scripts may
8320 edit. After <file>/etc/aliases</file> is edited the program or
8321 human editing it must call <prgn>newaliases</prgn>. All MTA
8322 packages must come with a <prgn>newaliases</prgn> program,
8323 even if it does nothing, but older MTA packages did not do
8324 this so programs should not fail if <prgn>newaliases</prgn>
8325 cannot be found. Note that because of this, all MTA
8326 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8327 <tt>Replaces: mail-transport-agent</tt> control file
8332 The convention of writing <tt>forward to
8333 <var>address</var></tt> in the mailbox itself is not
8334 supported. Use a <tt>.forward</tt> file instead.</p>
8337 The <prgn>rmail</prgn> program used by UUCP
8338 for incoming mail should be <file>/usr/sbin/rmail</file>.
8339 Likewise, <prgn>rsmtp</prgn>, for receiving
8340 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8344 If your package needs to know what hostname to use on (for
8345 example) outgoing news and mail messages which are generated
8346 locally, you should use the file <file>/etc/mailname</file>. It
8347 will contain the portion after the username and <tt>@</tt>
8348 (at) sign for email addresses of users on the machine
8349 (followed by a newline).
8353 Such a package should check for the existence of this file
8354 when it is being configured. If it exists, it should be
8355 used without comment, although an MTA's configuration script
8356 may wish to prompt the user even if it finds that this file
8357 exists. If the file does not exist, the package should
8358 prompt the user for the value (preferably using
8359 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8360 as well as using it in the package's configuration. The
8361 prompt should make it clear that the name will not just be
8362 used by that package. For example, in this situation the
8363 <tt>inn</tt> package could say something like:
8364 <example compact="compact">
8365 Please enter the "mail name" of your system. This is the
8366 hostname portion of the address to be shown on outgoing
8367 news and mail messages. The default is
8368 <var>syshostname</var>, your system's host name. Mail
8369 name ["<var>syshostname</var>"]:
8371 where <var>syshostname</var> is the output of <tt>hostname
8377 <heading>News system configuration</heading>
8380 All the configuration files related to the NNTP (news)
8381 servers and clients should be located under
8382 <file>/etc/news</file>.</p>
8385 There are some configuration issues that apply to a number
8386 of news clients and server packages on the machine. These
8390 <tag><file>/etc/news/organization</file></tag>
8392 A string which should appear as the
8393 organization header for all messages posted
8394 by NNTP clients on the machine
8397 <tag><file>/etc/news/server</file></tag>
8399 Contains the FQDN of the upstream NNTP
8400 server, or localhost if the local machine is
8405 Other global files may be added as required for cross-package news
8412 <heading>Programs for the X Window System</heading>
8415 <heading>Providing X support and package priorities</heading>
8418 Programs that can be configured with support for the X
8419 Window System must be configured to do so and must declare
8420 any package dependencies necessary to satisfy their
8421 runtime requirements when using the X Window System. If
8422 such a package is of higher priority than the X packages
8423 on which it depends, it is required that either the
8424 X-specific components be split into a separate package, or
8425 that an alternative version of the package, which includes
8426 X support, be provided, or that the package's priority be
8432 <heading>Packages providing an X server</heading>
8435 Packages that provide an X server that, directly or
8436 indirectly, communicates with real input and display
8437 hardware should declare in their control data that they
8438 provide the virtual package <tt>xserver</tt>.<footnote>
8439 This implements current practice, and provides an
8440 actual policy for usage of the <tt>xserver</tt>
8441 virtual package which appears in the virtual packages
8442 list. In a nutshell, X servers that interface
8443 directly with the display and input hardware or via
8444 another subsystem (e.g., GGI) should provide
8445 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8446 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8452 <heading>Packages providing a terminal emulator</heading>
8455 Packages that provide a terminal emulator for the X Window
8456 System which meet the criteria listed below should declare
8457 in their control data that they provide the virtual
8458 package <tt>x-terminal-emulator</tt>. They should also
8459 register themselves as an alternative for
8460 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8465 To be an <tt>x-terminal-emulator</tt>, a program must:
8466 <list compact="compact">
8468 Be able to emulate a DEC VT100 terminal, or a
8469 compatible terminal.
8473 Support the command-line option <tt>-e
8474 <var>command</var></tt>, which creates a new
8475 terminal window<footnote>
8476 "New terminal window" does not necessarily mean
8477 a new top-level X window directly parented by
8478 the window manager; it could, if the terminal
8479 emulator application were so coded, be a new
8480 "view" in a multiple-document interface (MDI).
8482 and runs the specified <var>command</var>,
8483 interpreting the entirety of the rest of the command
8484 line as a command to pass straight to exec, in the
8485 manner that <tt>xterm</tt> does.
8489 Support the command-line option <tt>-T
8490 <var>title</var></tt>, which creates a new terminal
8491 window with the window title <var>title</var>.
8498 <heading>Packages providing a window manager</heading>
8501 Packages that provide a window manager should declare in
8502 their control data that they provide the virtual package
8503 <tt>x-window-manager</tt>. They should also register
8504 themselves as an alternative for
8505 <file>/usr/bin/x-window-manager</file>, with a priority
8506 calculated as follows:
8507 <list compact="compact">
8509 Start with a priority of 20.
8513 If the window manager supports the Debian menu
8514 system, add 20 points if this support is available
8515 in the package's default configuration (i.e., no
8516 configuration files belonging to the system or user
8517 have to be edited to activate the feature); if
8518 configuration files must be modified, add only 10
8524 If the window manager complies with <url
8525 id="http://www.freedesktop.org/Standards/wm-spec"
8526 name="The Window Manager Specification Project">,
8527 written by the <url id="http://www.freedesktop.org/"
8528 name="Free Desktop Group">, add 40 points.
8532 If the window manager permits the X session to be
8533 restarted using a <em>different</em> window manager
8534 (without killing the X server) in its default
8535 configuration, add 10 points; otherwise add none.
8542 <heading>Packages providing fonts</heading>
8545 Packages that provide fonts for the X Window
8547 For the purposes of Debian Policy, a "font for the X
8548 Window System" is one which is accessed via X protocol
8549 requests. Fonts for the Linux console, for PostScript
8550 renderer, or any other purpose, do not fit this
8551 definition. Any tool which makes such fonts available
8552 to the X Window System, however, must abide by this
8555 must do a number of things to ensure that they are both
8556 available without modification of the X or font server
8557 configuration, and that they do not corrupt files used by
8558 other font packages to register information about
8562 Fonts of any type supported by the X Window System
8563 must be in a separate binary package from any
8564 executables, libraries, or documentation (except
8565 that specific to the fonts shipped, such as their
8566 license information). If one or more of the fonts
8567 so packaged are necessary for proper operation of
8568 the package with which they are associated the font
8569 package may be Recommended; if the fonts merely
8570 provide an enhancement, a Suggests relationship may
8571 be used. Packages must not Depend on font
8573 This is because the X server may retrieve fonts
8574 from the local file system or over the network
8575 from an X font server; the Debian package system
8576 is empowered to deal only with the local
8582 BDF fonts must be converted to PCF fonts with the
8583 <prgn>bdftopcf</prgn> utility (available in the
8584 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8585 placed in a directory that corresponds to their
8587 <list compact="compact">
8589 100 dpi fonts must be placed in
8590 <file>/usr/share/fonts/X11/100dpi/</file>.
8594 75 dpi fonts must be placed in
8595 <file>/usr/share/fonts/X11/75dpi/</file>.
8599 Character-cell fonts, cursor fonts, and other
8600 low-resolution fonts must be placed in
8601 <file>/usr/share/fonts/X11/misc/</file>.
8607 Type 1 fonts must be placed in
8608 <file>/usr/share/fonts/X11/Type1/</file>. If font
8609 metric files are available, they must be placed here
8614 Subdirectories of <file>/usr/share/fonts/X11/</file>
8615 other than those listed above must be neither
8616 created nor used. (The <file>PEX</file>, <file>CID</file>,
8617 <file>Speedo</file>, and <file>cyrillic</file> directories
8618 are excepted for historical reasons, but installation of
8619 files into these directories remains discouraged.)
8623 Font packages may, instead of placing files directly
8624 in the X font directories listed above, provide
8625 symbolic links in that font directory pointing to
8626 the files' actual location in the filesystem. Such
8627 a location must comply with the FHS.
8631 Font packages should not contain both 75dpi and
8632 100dpi versions of a font. If both are available,
8633 they should be provided in separate binary packages
8634 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8635 the names of the packages containing the
8636 corresponding fonts.
8640 Fonts destined for the <file>misc</file> subdirectory
8641 should not be included in the same package as 75dpi
8642 or 100dpi fonts; instead, they should be provided in
8643 a separate package with <tt>-misc</tt> appended to
8648 Font packages must not provide the files
8649 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8650 <file>fonts.scale</file> in a font directory:
8653 <file>fonts.dir</file> files must not be provided at all.
8657 <file>fonts.alias</file> and <file>fonts.scale</file>
8658 files, if needed, should be provided in the
8660 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8661 where <var>fontdir</var> is the name of the
8663 <file>/usr/share/fonts/X11/</file> where the
8664 package's corresponding fonts are stored
8665 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8666 <var>package</var> is the name of the package
8667 that provides these fonts, and
8668 <var>extension</var> is either <tt>scale</tt>
8669 or <tt>alias</tt>, whichever corresponds to
8676 Font packages must declare a dependency on
8677 <tt>xfonts-utils</tt> in their control
8682 Font packages that provide one or more
8683 <file>fonts.scale</file> files as described above must
8684 invoke <prgn>update-fonts-scale</prgn> on each
8685 directory into which they installed fonts
8686 <em>before</em> invoking
8687 <prgn>update-fonts-dir</prgn> on that directory.
8688 This invocation must occur in both the
8689 <prgn>postinst</prgn> (for all arguments) and
8690 <prgn>postrm</prgn> (for all arguments except
8691 <tt>upgrade</tt>) scripts.
8695 Font packages that provide one or more
8696 <file>fonts.alias</file> files as described above must
8697 invoke <prgn>update-fonts-alias</prgn> on each
8698 directory into which they installed fonts. This
8699 invocation must occur in both the
8700 <prgn>postinst</prgn> (for all arguments) and
8701 <prgn>postrm</prgn> (for all arguments except
8702 <tt>upgrade</tt>) scripts.
8706 Font packages must invoke
8707 <prgn>update-fonts-dir</prgn> on each directory into
8708 which they installed fonts. This invocation must
8709 occur in both the <prgn>postinst</prgn> (for all
8710 arguments) and <prgn>postrm</prgn> (for all
8711 arguments except <tt>upgrade</tt>) scripts.
8715 Font packages must not provide alias names for the
8716 fonts they include which collide with alias names
8717 already in use by fonts already packaged.
8721 Font packages must not provide fonts with the same
8722 XLFD registry name as another font already packaged.
8728 <sect1 id="appdefaults">
8729 <heading>Application defaults files</heading>
8732 Application defaults files must be installed in the
8733 directory <file>/etc/X11/app-defaults/</file> (use of a
8734 localized subdirectory of <file>/etc/X11/</file> as described
8735 in the <em>X Toolkit Intrinsics - C Language
8736 Interface</em> manual is also permitted). They must be
8737 registered as <tt>conffile</tt>s or handled as
8738 configuration files.
8742 Customization of programs' X resources may also be
8743 supported with the provision of a file with the same name
8744 as that of the package placed in
8745 the <file>/etc/X11/Xresources/</file> directory, which
8746 must be registered as a <tt>conffile</tt> or handled as a
8747 configuration file.<footnote>
8748 Note that this mechanism is not the same as using
8749 app-defaults; app-defaults are tied to the client
8750 binary on the local file system, whereas X resources
8751 are stored in the X server and affect all connecting
8758 <heading>Installation directory issues</heading>
8761 Historically, packages using the X Window System used a
8762 separate set of installation directories from other packages.
8763 This practice has been discontinued and packages using the X
8764 Window System should now generally be installed in the same
8765 directories as any other package. Specifically, packages must
8766 not install files under the <file>/usr/X11R6/</file> directory
8767 and the <file>/usr/X11R6/</file> directory hierarchy should be
8768 regarded as obsolete.
8772 Include files previously installed under
8773 <file>/usr/X11R6/include/X11/</file> should be installed into
8774 <file>/usr/include/X11/</file>. For files previously
8775 installed into subdirectories of
8776 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8777 determine if subdirectories of <file>/usr/lib/</file> and
8778 <file>/usr/share/</file> can be used. If not, a subdirectory
8779 of <file>/usr/lib/X11/</file> should be used.
8783 Configuration files for window, display, or session managers
8784 or other applications that are tightly integrated with the X
8785 Window System may be placed in a subdirectory
8786 of <file>/etc/X11/</file> corresponding to the package name.
8787 Other X Window System applications should use
8788 the <file>/etc/</file> directory unless otherwise mandated by
8789 policy (such as for <ref id="appdefaults">).
8794 <heading>The OSF/Motif and OpenMotif libraries</heading>
8797 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8798 OpenMotif libraries</em><footnote>
8799 OSF/Motif and OpenMotif are collectively referred to as
8800 "Motif" in this policy document.
8802 should be compiled against and tested with LessTif (a free
8803 re-implementation of Motif) instead. If the maintainer
8804 judges that the program or programs do not work
8805 sufficiently well with LessTif to be distributed and
8806 supported, but do so when compiled against Motif, then two
8807 versions of the package should be created; one linked
8808 statically against Motif and with <tt>-smotif</tt>
8809 appended to the package name, and one linked dynamically
8810 against Motif and with <tt>-dmotif</tt> appended to the
8815 Both Motif-linked versions are dependent
8816 upon non-DFSG-compliant software and thus cannot be
8817 uploaded to the <em>main</em> distribution; if the
8818 software is itself DFSG-compliant it may be uploaded to
8819 the <em>contrib</em> distribution. While known existing
8820 versions of Motif permit unlimited redistribution of
8821 binaries linked against the library (whether statically or
8822 dynamically), it is the package maintainer's
8823 responsibility to determine whether this is permitted by
8824 the license of the copy of Motif in their possession.
8830 <heading>Perl programs and modules</heading>
8833 Perl programs and modules should follow the current Perl policy.
8837 The Perl policy can be found in the <tt>perl-policy</tt>
8838 files in the <tt>debian-policy</tt> package.
8839 It is also available from the Debian web mirrors at
8840 <tt><url name="/doc/packaging-manuals/perl-policy/"
8841 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8846 <heading>Emacs lisp programs</heading>
8849 Please refer to the "Debian Emacs Policy" for details of how to
8850 package emacs lisp programs.
8854 The Emacs policy is available in
8855 <file>debian-emacs-policy.gz</file> of the
8856 <package>emacsen-common</package> package.
8857 It is also available from the Debian web mirrors at
8858 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8859 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8864 <heading>Games</heading>
8867 The permissions on <file>/var/games</file> are mode 755, owner
8868 <tt>root</tt> and group <tt>root</tt>.
8872 Each game decides on its own security policy.</p>
8875 Games which require protected, privileged access to
8876 high-score files, saved games, etc., may be made
8877 set-<em>group</em>-id (mode 2755) and owned by
8878 <tt>root:games</tt>, and use files and directories with
8879 appropriate permissions (770 <tt>root:games</tt>, for
8880 example). They must not be made
8881 set-<em>user</em>-id, as this causes security problems. (If
8882 an attacker can subvert any set-user-id game they can
8883 overwrite the executable of any other, causing other players
8884 of these games to run a Trojan horse program. With a
8885 set-group-id game the attacker only gets access to less
8886 important game data, and if they can get at the other
8887 players' accounts at all it will take considerably more
8891 Some packages, for example some fortune cookie programs, are
8892 configured by the upstream authors to install with their
8893 data files or other static information made unreadable so
8894 that they can only be accessed through set-id programs
8895 provided. You should not do this in a Debian package: anyone can
8896 download the <file>.deb</file> file and read the data from it,
8897 so there is no point making the files unreadable. Not
8898 making the files unreadable also means that you don't have
8899 to make so many programs set-id, which reduces the risk of a
8903 As described in the FHS, binaries of games should be
8904 installed in the directory <file>/usr/games</file>. This also
8905 applies to games that use the X Window System. Manual pages
8906 for games (X and non-X games) should be installed in
8907 <file>/usr/share/man/man6</file>.</p>
8913 <heading>Documentation</heading>
8916 <heading>Manual pages</heading>
8919 You should install manual pages in <prgn>nroff</prgn> source
8920 form, in appropriate places under <file>/usr/share/man</file>.
8921 You should only use sections 1 to 9 (see the FHS for more
8922 details). You must not install a pre-formatted "cat page".
8926 Each program, utility, and function should have an
8927 associated manual page included in the same package. It is
8928 suggested that all configuration files also have a manual
8929 page included as well. Manual pages for protocols and other
8930 auxiliary things are optional.
8934 If no manual page is available, this is considered as a bug
8935 and should be reported to the Debian Bug Tracking System (the
8936 maintainer of the package is allowed to write this bug report
8937 themselves, if they so desire). Do not close the bug report
8938 until a proper man page is available.<footnote>
8939 It is not very hard to write a man page. See the
8940 <url id="http://www.schweikhardt.net/man_page_howto.html"
8941 name="Man-Page-HOWTO">,
8942 <manref name="man" section="7">, the examples
8943 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8944 the helper programs <prgn>help2man</prgn>, or the
8945 directory <file>/usr/share/doc/man-db/examples</file>.
8950 You may forward a complaint about a missing man page to the
8951 upstream authors, and mark the bug as forwarded in the
8952 Debian bug tracking system. Even though the GNU Project do
8953 not in general consider the lack of a man page to be a bug,
8954 we do; if they tell you that they don't consider it a bug
8955 you should leave the bug in our bug tracking system open
8960 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8964 If one man page needs to be accessible via several names it
8965 is better to use a symbolic link than the <file>.so</file>
8966 feature, but there is no need to fiddle with the relevant
8967 parts of the upstream source to change from <file>.so</file> to
8968 symlinks: don't do it unless it's easy. You should not
8969 create hard links in the manual page directories, nor put
8970 absolute filenames in <file>.so</file> directives. The filename
8971 in a <file>.so</file> in a man page should be relative to the
8972 base of the man page tree (usually
8973 <file>/usr/share/man</file>). If you do not create any links
8974 (whether symlinks, hard links, or <tt>.so</tt> directives)
8975 in the file system to the alternate names of the man page,
8976 then you should not rely on <prgn>man</prgn> finding your
8977 man page under those names based solely on the information in
8978 the man page's header.<footnote>
8979 Supporting this in <prgn>man</prgn> often requires
8980 unreasonable processing time to find a manual page or to
8981 report that none exists, and moves knowledge into man's
8982 database that would be better left in the file system.
8983 This support is therefore deprecated and will cease to
8984 be present in the future.
8989 Manual pages in locale-specific subdirectories of
8990 <file>/usr/share/man</file> should use either UTF-8 or the usual
8991 legacy encoding for that language (normally the one corresponding
8992 to the shortest relevant locale name in
8993 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
8994 <file>/usr/share/man/fr</file> should use either UTF-8 or
8995 ISO-8859-1.<footnote>
8996 <prgn>man</prgn> will automatically detect whether UTF-8 is in
8997 use. In future, all manual pages will be required to use
9003 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9004 included in the subdirectory name unless it indicates a
9005 significant difference in the language, as this excludes
9006 speakers of the language in other countries.<footnote>
9007 At the time of writing, Chinese and Portuguese are the main
9008 languages with such differences, so <file>pt_BR</file>,
9009 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9014 If a localized version of a manual page is provided, it should
9015 either be up-to-date or it should be obvious to the reader that
9016 it is outdated and the original manual page should be used
9017 instead. This can be done either by a note at the beginning of
9018 the manual page or by showing the missing or changed portions in
9019 the original language instead of the target language.
9024 <heading>Info documents</heading>
9027 Info documents should be installed in <file>/usr/share/info</file>.
9028 They should be compressed with <tt>gzip -9</tt>.
9032 The <prgn>install-info</prgn> program maintains a directory of
9033 installed info documents in <file>/usr/share/info/dir</file> for
9034 the use of info readers.<footnote>
9035 It was previously necessary for packages installing info
9036 documents to run <prgn>install-info</prgn> from maintainer
9037 scripts. This is no longer necessary. The installation
9038 system now uses dpkg triggers.
9040 This file must not be included in packages. Packages containing
9041 info documents should depend on <tt>dpkg (>= 1.15.4) |
9042 install-info</tt> to ensure that the directory file is properly
9043 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9048 Info documents should contain section and directory entry
9049 information in the document for the use
9050 of <prgn>install-info</prgn>. The section should be specified
9051 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9052 space and the section of this info page. The directory entry or
9053 entries should be included between
9054 a <tt>START-INFO-DIR-ENTRY</tt> line and
9055 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9057 INFO-DIR-SECTION Individual utilities
9058 START-INFO-DIR-ENTRY
9059 * example: (example). An example info directory entry.
9062 To determine which section to use, you should look
9063 at <file>/usr/share/info/dir</file> on your system and choose
9064 the most relevant (or create a new section if none of the
9065 current sections are relevant).<footnote>
9066 Normally, info documents are generated from Texinfo source.
9067 To include this information in the generated info document, if
9068 it is absent, add commands like:
9070 @dircategory Individual utilities
9072 * example: (example). An example info directory entry.
9075 to the Texinfo source of the document and ensure that the info
9076 documents are rebuilt from source during the package build.
9082 <heading>Additional documentation</heading>
9085 Any additional documentation that comes with the package may
9086 be installed at the discretion of the package maintainer.
9087 Plain text documentation should be installed in the directory
9088 <file>/usr/share/doc/<var>package</var></file>, where
9089 <var>package</var> is the name of the package, and
9090 compressed with <tt>gzip -9</tt> unless it is small.
9094 If a package comes with large amounts of documentation which
9095 many users of the package will not require you should create
9096 a separate binary package to contain it, so that it does not
9097 take up disk space on the machines of users who do not need
9098 or want it installed.</p>
9101 It is often a good idea to put text information files
9102 (<file>README</file>s, changelogs, and so forth) that come with
9103 the source package in <file>/usr/share/doc/<var>package</var></file>
9104 in the binary package. However, you don't need to install
9105 the instructions for building and installing the package, of
9109 Packages must not require the existence of any files in
9110 <file>/usr/share/doc/</file> in order to function
9112 The system administrator should be able to
9113 delete files in <file>/usr/share/doc/</file> without causing
9114 any programs to break.
9116 Any files that are referenced by programs but are also
9117 useful as stand alone documentation should be installed under
9118 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9119 <file>/usr/share/doc/<var>package</var></file>.
9123 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9124 link to another directory in <file>/usr/share/doc</file> only if
9125 the two packages both come from the same source and the
9126 first package Depends on the second.<footnote>
9128 Please note that this does not override the section on
9129 changelog files below, so the file
9130 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9131 must refer to the changelog for the current version of
9132 <var>package</var> in question. In practice, this means
9133 that the sources of the target and the destination of the
9134 symlink must be the same (same source package and
9141 Former Debian releases placed all additional documentation
9142 in <file>/usr/doc/<var>package</var></file>. This has been
9143 changed to <file>/usr/share/doc/<var>package</var></file>,
9144 and packages must not put documentation in the directory
9145 <file>/usr/doc/<var>package</var></file>. <footnote>
9146 At this phase of the transition, we no longer require a
9147 symbolic link in <file>/usr/doc/</file>. At a later point,
9148 policy shall change to make the symbolic links a bug.
9154 <heading>Preferred documentation formats</heading>
9157 The unification of Debian documentation is being carried out
9161 If your package comes with extensive documentation in a
9162 markup format that can be converted to various other formats
9163 you should if possible ship HTML versions in a binary
9164 package, in the directory
9165 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9166 its subdirectories.<footnote>
9167 The rationale: The important thing here is that HTML
9168 docs should be available in <em>some</em> package, not
9169 necessarily in the main binary package.
9174 Other formats such as PostScript may be provided at the
9175 package maintainer's discretion.
9179 <sect id="copyrightfile">
9180 <heading>Copyright information</heading>
9183 Every package must be accompanied by a verbatim copy of its
9184 copyright information and distribution license in the file
9185 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9186 file must neither be compressed nor be a symbolic link.
9190 In addition, the copyright file must say where the upstream
9191 sources (if any) were obtained. It should name the original
9192 authors of the package and the Debian maintainer(s) who were
9193 involved with its creation.
9197 Packages in the <em>contrib</em> or <em>non-free</em> archive
9198 areas should state in the copyright file that the package is not
9199 part of the Debian GNU/Linux distribution and briefly explain
9204 A copy of the file which will be installed in
9205 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9206 be in <file>debian/copyright</file> in the source package.
9210 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9211 link to another directory in <file>/usr/share/doc</file> only if
9212 the two packages both come from the same source and the
9213 first package Depends on the second. These rules are
9214 important because copyrights must be extractable by
9219 Packages distributed under the UCB BSD license, the Apache
9220 license (version 2.0), the Artistic license, the GNU GPL
9221 (version 2 or 3), the GNU LGPL (versions 2, 2.1, or 3), and the
9222 GNU FDL (versions 1.2 or 1.3) should refer to the corresponding
9223 files under <file>/usr/share/common-licenses</file>,<footnote>
9226 <file>/usr/share/common-licenses/BSD</file>,
9227 <file>/usr/share/common-licenses/Apache-2.0</file>,
9228 <file>/usr/share/common-licenses/Artistic</file>,
9229 <file>/usr/share/common-licenses/GPL-2</file>,
9230 <file>/usr/share/common-licenses/GPL-3</file>,
9231 <file>/usr/share/common-licenses/LGPL-2</file>,
9232 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9233 <file>/usr/share/common-licenses/LGPL-3</file>,
9234 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9235 <file>/usr/share/common-licenses/GFDL-1.3</file>
9238 </footnote> rather than quoting them in the copyright
9243 You should not use the copyright file as a general <file>README</file>
9244 file. If your package has such a file it should be
9245 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9246 <file>README.Debian</file> or some other appropriate place.</p>
9250 <heading>Examples</heading>
9253 Any examples (configurations, source files, whatever),
9254 should be installed in a directory
9255 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9256 files should not be referenced by any program: they're there
9257 for the benefit of the system administrator and users as
9258 documentation only. Architecture-specific example files
9259 should be installed in a directory
9260 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9262 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9263 latter directory itself may be a symbolic link to the
9268 If the purpose of a package is to provide examples, then the
9269 example files may be installed into
9270 <file>/usr/share/doc/<var>package</var></file>.
9274 <sect id="changelogs">
9275 <heading>Changelog files</heading>
9278 Packages that are not Debian-native must contain a
9279 compressed copy of the <file>debian/changelog</file> file from
9280 the Debian source tree in
9281 <file>/usr/share/doc/<var>package</var></file> with the name
9282 <file>changelog.Debian.gz</file>.
9286 If an upstream changelog is available, it should be accessible as
9287 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9288 plain text. If the upstream changelog is distributed in
9289 HTML, it should be made available in that form as
9290 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9291 and a plain text <file>changelog.gz</file> should be generated
9292 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9293 the upstream changelog files do not already conform to this
9294 naming convention, then this may be achieved either by
9295 renaming the files, or by adding a symbolic link, at the
9296 maintainer's discretion.<footnote>
9297 Rationale: People should not have to look in places for
9298 upstream changelogs merely because they are given
9299 different names or are distributed in HTML format.
9304 All of these files should be installed compressed using
9305 <tt>gzip -9</tt>, as they will become large with time even
9306 if they start out small.
9310 If the package has only one changelog which is used both as
9311 the Debian changelog and the upstream one because there is
9312 no separate upstream maintainer then that changelog should
9313 usually be installed as
9314 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9315 there is a separate upstream maintainer, but no upstream
9316 changelog, then the Debian changelog should still be called
9317 <file>changelog.Debian.gz</file>.
9321 For details about the format and contents of the Debian
9322 changelog file, please see <ref id="dpkgchangelog">.
9327 <appendix id="pkg-scope">
9328 <heading>Introduction and scope of these appendices</heading>
9331 These appendices are taken essentially verbatim from the
9332 now-deprecated Packaging Manual, version 3.2.1.0. They are
9333 the chapters which are likely to be of use to package
9334 maintainers and which have not already been included in the
9335 policy document itself. Most of these sections are very likely
9336 not relevant to policy; they should be treated as
9337 documentation for the packaging system. Please note that these
9338 appendices are included for convenience, and for historical
9339 reasons: they used to be part of policy package, and they have
9340 not yet been incorporated into dpkg documentation. However,
9341 they still have value, and hence they are presented here.
9345 They have not yet been checked to ensure that they are
9346 compatible with the contents of policy, and if there are any
9347 contradictions, the version in the main policy document takes
9348 precedence. The remaining chapters of the old Packaging
9349 Manual have also not been read in detail to ensure that there
9350 are not parts which have been left out. Both of these will be
9355 Certain parts of the Packaging manual were integrated into the
9356 Policy Manual proper, and removed from the appendices. Links
9357 have been placed from the old locations to the new ones.
9361 <prgn>dpkg</prgn> is a suite of programs for creating binary
9362 package files and installing and removing them on Unix
9364 <prgn>dpkg</prgn> is targeted primarily at Debian
9365 GNU/Linux, but may work on or be ported to other
9371 The binary packages are designed for the management of
9372 installed executable programs (usually compiled binaries) and
9373 their associated data, though source code examples and
9374 documentation are provided as part of some packages.</p>
9377 This manual describes the technical aspects of creating Debian
9378 binary packages (<file>.deb</file> files). It documents the
9379 behavior of the package management programs
9380 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9381 they interact with packages.</p>
9384 It also documents the interaction between
9385 <prgn>dselect</prgn>'s core and the access method scripts it
9386 uses to actually install the selected packages, and describes
9387 how to create a new access method.</p>
9390 This manual does not go into detail about the options and
9391 usage of the package building and installation tools. It
9392 should therefore be read in conjunction with those programs'
9397 The utility programs which are provided with <prgn>dpkg</prgn>
9398 for managing various system configuration and similar issues,
9399 such as <prgn>update-rc.d</prgn> and
9400 <prgn>install-info</prgn>, are not described in detail here -
9401 please see their man pages.
9405 It is assumed that the reader is reasonably familiar with the
9406 <prgn>dpkg</prgn> System Administrators' manual.
9407 Unfortunately this manual does not yet exist.
9411 The Debian version of the FSF's GNU hello program is provided
9412 as an example for people wishing to create Debian
9413 packages. The Debian <prgn>debmake</prgn> package is
9414 recommended as a very helpful tool in creating and maintaining
9415 Debian packages. However, while the tools and examples are
9416 helpful, they do not replace the need to read and follow the
9417 Policy and Programmer's Manual.</p>
9420 <appendix id="pkg-binarypkg">
9421 <heading>Binary packages (from old Packaging Manual)</heading>
9424 The binary package has two main sections. The first part
9425 consists of various control information files and scripts used
9426 by <prgn>dpkg</prgn> when installing and removing. See <ref
9427 id="pkg-controlarea">.
9431 The second part is an archive containing the files and
9432 directories to be installed.
9436 In the future binary packages may also contain other
9437 components, such as checksums and digital signatures. The
9438 format for the archive is described in full in the
9439 <file>deb(5)</file> man page.
9443 <sect id="pkg-bincreating"><heading>Creating package files -
9444 <prgn>dpkg-deb</prgn>
9448 All manipulation of binary package files is done by
9449 <prgn>dpkg-deb</prgn>; it's the only program that has
9450 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9451 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9452 will spot that the options requested are appropriate to
9453 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9458 In order to create a binary package you must make a
9459 directory tree which contains all the files and directories
9460 you want to have in the file system data part of the package.
9461 In Debian-format source packages this directory is usually
9462 <file>debian/tmp</file>, relative to the top of the package's
9467 They should have the locations (relative to the root of the
9468 directory tree you're constructing) ownerships and
9469 permissions which you want them to have on the system when
9474 With current versions of <prgn>dpkg</prgn> the uid/username
9475 and gid/groupname mappings for the users and groups being
9476 used should be the same on the system where the package is
9477 built and the one where it is installed.
9481 You need to add one special directory to the root of the
9482 miniature file system tree you're creating:
9483 <prgn>DEBIAN</prgn>. It should contain the control
9484 information files, notably the binary package control file
9485 (see <ref id="pkg-controlfile">).
9489 The <prgn>DEBIAN</prgn> directory will not appear in the
9490 file system archive of the package, and so won't be installed
9491 by <prgn>dpkg</prgn> when the package is installed.
9495 When you've prepared the package, you should invoke:
9497 dpkg --build <var>directory</var>
9502 This will build the package in
9503 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9504 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9505 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9510 See the man page <manref name="dpkg-deb" section="8"> for details of how
9511 to examine the contents of this newly-created file. You may find the
9512 output of following commands enlightening:
9514 dpkg-deb --info <var>filename</var>.deb
9515 dpkg-deb --contents <var>filename</var>.deb
9516 dpkg --contents <var>filename</var>.deb
9518 To view the copyright file for a package you could use this command:
9520 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9525 <sect id="pkg-controlarea">
9526 <heading>Package control information files</heading>
9529 The control information portion of a binary package is a
9530 collection of files with names known to <prgn>dpkg</prgn>.
9531 It will treat the contents of these files specially - some
9532 of them contain information used by <prgn>dpkg</prgn> when
9533 installing or removing the package; others are scripts which
9534 the package maintainer wants <prgn>dpkg</prgn> to run.
9538 It is possible to put other files in the package control
9539 area, but this is not generally a good idea (though they
9540 will largely be ignored).
9544 Here is a brief list of the control info files supported by
9545 <prgn>dpkg</prgn> and a summary of what they're used for.
9550 <tag><tt>control</tt>
9553 This is the key description file used by
9554 <prgn>dpkg</prgn>. It specifies the package's name
9555 and version, gives its description for the user,
9556 states its relationships with other packages, and so
9557 forth. See <ref id="sourcecontrolfiles"> and
9558 <ref id="binarycontrolfiles">.
9562 It is usually generated automatically from information
9563 in the source package by the
9564 <prgn>dpkg-gencontrol</prgn> program, and with
9565 assistance from <prgn>dpkg-shlibdeps</prgn>.
9566 See <ref id="pkg-sourcetools">.
9570 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9575 These are executable files (usually scripts) which
9576 <prgn>dpkg</prgn> runs during installation, upgrade
9577 and removal of packages. They allow the package to
9578 deal with matters which are particular to that package
9579 or require more complicated processing than that
9580 provided by <prgn>dpkg</prgn>. Details of when and
9581 how they are called are in <ref id="maintainerscripts">.
9585 It is very important to make these scripts idempotent.
9586 See <ref id="idempotency">.
9590 The maintainer scripts are not guaranteed to run with a
9591 controlling terminal and may not be able to interact with
9592 the user. See <ref id="controllingterminal">.
9596 <tag><tt>conffiles</tt>
9599 This file contains a list of configuration files which
9600 are to be handled automatically by <prgn>dpkg</prgn>
9601 (see <ref id="pkg-conffiles">). Note that not necessarily
9602 every configuration file should be listed here.
9605 <tag><tt>shlibs</tt>
9608 This file contains a list of the shared libraries
9609 supplied by the package, with dependency details for
9610 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9611 when it determines what dependencies are required in a
9612 package control file. The <tt>shlibs</tt> file format
9613 is described on <ref id="shlibs">.
9618 <sect id="pkg-controlfile">
9619 <heading>The main control information file: <tt>control</tt></heading>
9622 The most important control information file used by
9623 <prgn>dpkg</prgn> when it installs a package is
9624 <tt>control</tt>. It contains all the package's "vital
9629 The binary package control files of packages built from
9630 Debian sources are made by a special tool,
9631 <prgn>dpkg-gencontrol</prgn>, which reads
9632 <file>debian/control</file> and <file>debian/changelog</file> to
9633 find the information it needs. See <ref id="pkg-sourcepkg"> for
9638 The fields in binary package control files are listed in
9639 <ref id="binarycontrolfiles">.
9643 A description of the syntax of control files and the purpose
9644 of the fields is available in <ref id="controlfields">.
9649 <heading>Time Stamps</heading>
9652 See <ref id="timestamps">.
9657 <appendix id="pkg-sourcepkg">
9658 <heading>Source packages (from old Packaging Manual) </heading>
9661 The Debian binary packages in the distribution are generated
9662 from Debian sources, which are in a special format to assist
9663 the easy and automatic building of binaries.
9666 <sect id="pkg-sourcetools">
9667 <heading>Tools for processing source packages</heading>
9670 Various tools are provided for manipulating source packages;
9671 they pack and unpack sources and help build of binary
9672 packages and help manage the distribution of new versions.
9676 They are introduced and typical uses described here; see
9677 <manref name="dpkg-source" section="1"> for full
9678 documentation about their arguments and operation.
9682 For examples of how to construct a Debian source package,
9683 and how to use those utilities that are used by Debian
9684 source packages, please see the <prgn>hello</prgn> example
9688 <sect1 id="pkg-dpkg-source">
9690 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9695 This program is frequently used by hand, and is also
9696 called from package-independent automated building scripts
9697 such as <prgn>dpkg-buildpackage</prgn>.
9701 To unpack a package it is typically invoked with
9703 dpkg-source -x <var>.../path/to/filename</var>.dsc
9708 with the <file><var>filename</var>.tar.gz</file> and
9709 <file><var>filename</var>.diff.gz</file> (if applicable) in
9710 the same directory. It unpacks into
9711 <file><var>package</var>-<var>version</var></file>, and if
9713 <file><var>package</var>-<var>version</var>.orig</file>, in
9714 the current directory.
9718 To create a packed source archive it is typically invoked:
9720 dpkg-source -b <var>package</var>-<var>version</var>
9725 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9726 <file>.diff.gz</file> (if appropriate) in the current
9727 directory. <prgn>dpkg-source</prgn> does not clean the
9728 source tree first - this must be done separately if it is
9733 See also <ref id="pkg-sourcearchives">.</p>
9737 <sect1 id="pkg-dpkg-buildpackage">
9739 <prgn>dpkg-buildpackage</prgn> - overall package-building
9744 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9745 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9746 targets <tt>clean</tt>, <tt>build</tt> and
9747 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9748 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9749 source and binary package upload.
9753 It is usually invoked by hand from the top level of the
9754 built or unbuilt source directory. It may be invoked with
9755 no arguments; useful arguments include:
9756 <taglist compact="compact">
9757 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9760 Do not sign the <tt>.changes</tt> file or the
9761 source package <tt>.dsc</tt> file, respectively.</p>
9763 <tag><tt>-p<var>sign-command</var></tt></tag>
9766 Invoke <var>sign-command</var> instead of finding
9767 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9768 <var>sign-command</var> must behave just like
9769 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9771 <tag><tt>-r<var>root-command</var></tt></tag>
9774 When root privilege is required, invoke the command
9775 <var>root-command</var>. <var>root-command</var>
9776 should invoke its first argument as a command, from
9777 the <prgn>PATH</prgn> if necessary, and pass its
9778 second and subsequent arguments to the command it
9779 calls. If no <var>root-command</var> is supplied
9780 then <var>dpkg-buildpackage</var> will take no
9781 special action to gain root privilege, so that for
9782 most packages it will have to be invoked as root to
9785 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9788 Two types of binary-only build and upload - see
9789 <manref name="dpkg-source" section="1">.
9796 <sect1 id="pkg-dpkg-gencontrol">
9798 <prgn>dpkg-gencontrol</prgn> - generates binary package
9803 This program is usually called from <file>debian/rules</file>
9804 (see <ref id="pkg-sourcetree">) in the top level of the source
9809 This is usually done just before the files and directories in the
9810 temporary directory tree where the package is being built have their
9811 permissions and ownerships set and the package is constructed using
9812 <prgn>dpkg-deb/</prgn>
9814 This is so that the control file which is produced has
9815 the right permissions
9820 <prgn>dpkg-gencontrol</prgn> must be called after all the
9821 files which are to go into the package have been placed in
9822 the temporary build directory, so that its calculation of
9823 the installed size of a package is correct.
9827 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9828 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9829 variable substitutions created by
9830 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9835 For a package which generates only one binary package, and
9836 which builds it in <file>debian/tmp</file> relative to the top
9837 of the source package, it is usually sufficient to call
9838 <prgn>dpkg-gencontrol</prgn>.
9842 Sources which build several binaries will typically need
9845 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9846 </example> The <tt>-P</tt> tells
9847 <prgn>dpkg-gencontrol</prgn> that the package is being
9848 built in a non-default directory, and the <tt>-p</tt>
9849 tells it which package's control file should be generated.
9853 <prgn>dpkg-gencontrol</prgn> also adds information to the
9854 list of files in <file>debian/files</file>, for the benefit of
9855 (for example) a future invocation of
9856 <prgn>dpkg-genchanges</prgn>.</p>
9859 <sect1 id="pkg-dpkg-shlibdeps">
9861 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9866 This program is usually called from <file>debian/rules</file>
9867 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9868 id="pkg-sourcetree">), in the top level of the source tree.
9872 Its arguments are executables and shared libraries
9875 They may be specified either in the locations in the
9876 source tree where they are created or in the locations
9877 in the temporary build tree where they are installed
9878 prior to binary package creation.
9880 </footnote> for which shared library dependencies should
9881 be included in the binary package's control file.
9885 If some of the found shared libraries should only
9886 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9887 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9888 by using the <tt>-d<var>dependency-field</var></tt> option
9889 before those executable(s). (Each <tt>-d</tt> option
9890 takes effect until the next <tt>-d</tt>.)
9894 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9895 output control file to be modified. Instead by default it
9896 adds to the <file>debian/substvars</file> file variable
9897 settings like <tt>shlibs:Depends</tt>. These variable
9898 settings must be referenced in dependency fields in the
9899 appropriate per-binary-package sections of the source
9904 For example, a package that generates an essential part
9905 which requires dependencies, and optional parts that
9906 which only require a recommendation, would separate those
9907 two sets of dependencies into two different fields.<footnote>
9908 At the time of writing, an example for this was the
9909 <package/xmms/ package, with Depends used for the xmms
9910 executable, Recommends for the plug-ins and Suggests for
9911 even more optional features provided by unzip.
9913 It can say in its <file>debian/rules</file>:
9915 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9916 -dRecommends <var>optionalpart anotheroptionalpart</var>
9918 and then in its main control file <file>debian/control</file>:
9921 Depends: ${shlibs:Depends}
9922 Recommends: ${shlibs:Recommends}
9928 Sources which produce several binary packages with
9929 different shared library dependency requirements can use
9930 the <tt>-p<var>varnameprefix</var></tt> option to override
9931 the default <tt>shlibs:</tt> prefix (one invocation of
9932 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9933 They can thus produce several sets of dependency
9934 variables, each of the form
9935 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9936 which can be referred to in the appropriate parts of the
9937 binary package control files.
9942 <sect1 id="pkg-dpkg-distaddfile">
9944 <prgn>dpkg-distaddfile</prgn> - adds a file to
9945 <file>debian/files</file>
9949 Some packages' uploads need to include files other than
9950 the source and binary package files.
9954 <prgn>dpkg-distaddfile</prgn> adds a file to the
9955 <file>debian/files</file> file so that it will be included in
9956 the <file>.changes</file> file when
9957 <prgn>dpkg-genchanges</prgn> is run.
9961 It is usually invoked from the <tt>binary</tt> target of
9962 <file>debian/rules</file>:
9964 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9966 The <var>filename</var> is relative to the directory where
9967 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9968 is usually the directory above the top level of the source
9969 tree. The <file>debian/rules</file> target should put the
9970 file there just before or just after calling
9971 <prgn>dpkg-distaddfile</prgn>.
9975 The <var>section</var> and <var>priority</var> are passed
9976 unchanged into the resulting <file>.changes</file> file.
9981 <sect1 id="pkg-dpkg-genchanges">
9983 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
9988 This program is usually called by package-independent
9989 automatic building scripts such as
9990 <prgn>dpkg-buildpackage</prgn>, but it may also be called
9995 It is usually called in the top level of a built source
9996 tree, and when invoked with no arguments will print out a
9997 straightforward <file>.changes</file> file based on the
9998 information in the source package's changelog and control
9999 file and the binary and source packages which should have
10005 <sect1 id="pkg-dpkg-parsechangelog">
10007 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10008 representation of a changelog
10012 This program is used internally by
10013 <prgn>dpkg-source</prgn> et al. It may also occasionally
10014 be useful in <file>debian/rules</file> and elsewhere. It
10015 parses a changelog, <file>debian/changelog</file> by default,
10016 and prints a control-file format representation of the
10017 information in it to standard output.
10021 <sect1 id="pkg-dpkg-architecture">
10023 <prgn>dpkg-architecture</prgn> - information about the build and
10028 This program can be used manually, but is also invoked by
10029 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10030 environment or make variables which specify the build and host
10031 architecture for the package building process.
10036 <sect id="pkg-sourcetree">
10037 <heading>The Debianised source tree</heading>
10040 The source archive scheme described later is intended to
10041 allow a Debianised source tree with some associated control
10042 information to be reproduced and transported easily. The
10043 Debianised source tree is a version of the original program
10044 with certain files added for the benefit of the
10045 Debianisation process, and with any other changes required
10046 made to the rest of the source code and installation
10051 The extra files created for Debian are in the subdirectory
10052 <file>debian</file> of the top level of the Debianised source
10053 tree. They are described below.
10056 <sect1 id="pkg-debianrules">
10057 <heading><file>debian/rules</file> - the main building script</heading>
10060 See <ref id="debianrules">.
10064 <sect1 id="pkg-srcsubstvars">
10065 <heading><file>debian/substvars</file> and variable substitutions</heading>
10068 See <ref id="substvars">.
10074 <heading><file>debian/files</file></heading>
10077 See <ref id="debianfiles">.
10081 <sect1><heading><file>debian/tmp</file>
10085 This is the canonical temporary location for the
10086 construction of binary packages by the <tt>binary</tt>
10087 target. The directory <file>tmp</file> serves as the root of
10088 the file system tree as it is being constructed (for
10089 example, by using the package's upstream makefiles install
10090 targets and redirecting the output there), and it also
10091 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10092 id="pkg-bincreating">.
10096 If several binary packages are generated from the same
10097 source tree it is usual to use several
10098 <file>debian/tmp<var>something</var></file> directories, for
10099 example <file>tmp-a</file> or <file>tmp-doc</file>.
10103 Whatever <file>tmp</file> directories are created and used by
10104 <tt>binary</tt> must of course be removed by the
10105 <tt>clean</tt> target.</p></sect1>
10109 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10113 As it exists on the FTP site, a Debian source package
10114 consists of three related files. You must have the right
10115 versions of all three to be able to use them.
10120 <tag>Debian source control file - <tt>.dsc</tt></tag>
10122 This file is a control file used by <prgn>dpkg-source</prgn>
10123 to extract a source package.
10124 See <ref id="debiansourcecontrolfiles">.
10128 Original source archive -
10130 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10136 This is a compressed (with <tt>gzip -9</tt>)
10137 <prgn>tar</prgn> file containing the source code from
10138 the upstream authors of the program.
10143 Debianisation diff -
10145 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10151 This is a unified context diff (<tt>diff -u</tt>)
10152 giving the changes which are required to turn the
10153 original source into the Debian source. These changes
10154 may only include editing and creating plain files.
10155 The permissions of files, the targets of symbolic
10156 links and the characteristics of special files or
10157 pipes may not be changed and no files may be removed
10162 All the directories in the diff must exist, except the
10163 <file>debian</file> subdirectory of the top of the source
10164 tree, which will be created by
10165 <prgn>dpkg-source</prgn> if necessary when unpacking.
10169 The <prgn>dpkg-source</prgn> program will
10170 automatically make the <file>debian/rules</file> file
10171 executable (see below).</p></item>
10176 If there is no original source code - for example, if the
10177 package is specially prepared for Debian or the Debian
10178 maintainer is the same as the upstream maintainer - the
10179 format is slightly different: then there is no diff, and the
10181 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10182 and preferably contains a directory named
10183 <file><var>package</var>-<var>version</var></file>.
10188 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10191 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10192 Debian source package. However, if it is not available it
10193 is possible to unpack a Debian source archive as follows:
10194 <enumlist compact="compact">
10197 Untar the tarfile, which will create a <file>.orig</file>
10201 <p>Rename the <file>.orig</file> directory to
10202 <file><var>package</var>-<var>version</var></file>.</p>
10206 Create the subdirectory <file>debian</file> at the top of
10207 the source tree.</p>
10209 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10211 <item><p>Untar the tarfile again if you want a copy of the original
10212 source code alongside the Debianised version.</p>
10217 It is not possible to generate a valid Debian source archive
10218 without using <prgn>dpkg-source</prgn>. In particular,
10219 attempting to use <prgn>diff</prgn> directly to generate the
10220 <file>.diff.gz</file> file will not work.
10224 <heading>Restrictions on objects in source packages</heading>
10227 The source package may not contain any hard links
10229 This is not currently detected when building source
10230 packages, but only when extracting
10234 Hard links may be permitted at some point in the
10235 future, but would require a fair amount of
10237 </footnote>, device special files, sockets or setuid or
10240 Setgid directories are allowed.
10245 The source packaging tools manage the changes between the
10246 original and Debianised source using <prgn>diff</prgn> and
10247 <prgn>patch</prgn>. Turning the original source tree as
10248 included in the <file>.orig.tar.gz</file> into the debianised
10249 source must not involve any changes which cannot be
10250 handled by these tools. Problematic changes which cause
10251 <prgn>dpkg-source</prgn> to halt with an error when
10252 building the source package are:
10253 <list compact="compact">
10254 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10256 <item><p>Changing the targets of symbolic links.</p>
10258 <item><p>Creating directories, other than <file>debian</file>.</p>
10260 <item><p>Changes to the contents of binary files.</p></item>
10261 </list> Changes which cause <prgn>dpkg-source</prgn> to
10262 print a warning but continue anyway are:
10263 <list compact="compact">
10266 Removing files, directories or symlinks.
10268 Renaming a file is not treated specially - it is
10269 seen as the removal of the old file (which
10270 generates a warning, but is otherwise ignored),
10271 and the creation of the new one.
10277 Changed text files which are missing the usual final
10278 newline (either in the original or the modified
10283 Changes which are not represented, but which are not detected by
10284 <prgn>dpkg-source</prgn>, are:
10285 <list compact="compact">
10286 <item><p>Changing the permissions of files (other than
10287 <file>debian/rules</file>) and directories.</p></item>
10292 The <file>debian</file> directory and <file>debian/rules</file>
10293 are handled specially by <prgn>dpkg-source</prgn> - before
10294 applying the changes it will create the <file>debian</file>
10295 directory, and afterwards it will make
10296 <file>debian/rules</file> world-executable.
10302 <appendix id="pkg-controlfields">
10303 <heading>Control files and their fields (from old Packaging Manual)</heading>
10306 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10307 data in a common format, known as control files. Binary and
10308 source packages have control data as do the <file>.changes</file>
10309 files which control the installation of uploaded files, and
10310 <prgn>dpkg</prgn>'s internal databases are in a similar
10315 <heading>Syntax of control files</heading>
10318 See <ref id="controlsyntax">.
10322 It is important to note that there are several fields which
10323 are optional as far as <prgn>dpkg</prgn> and the related
10324 tools are concerned, but which must appear in every Debian
10325 package, or whose omission may cause problems.
10330 <heading>List of fields</heading>
10333 See <ref id="controlfieldslist">.
10337 This section now contains only the fields that didn't belong
10338 to the Policy manual.
10341 <sect1 id="pkg-f-Filename">
10342 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10345 These fields in <tt>Packages</tt> files give the
10346 filename(s) of (the parts of) a package in the
10347 distribution directories, relative to the root of the
10348 Debian hierarchy. If the package has been split into
10349 several parts the parts are all listed in order, separated
10354 <sect1 id="pkg-f-Size">
10355 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10358 These fields in <file>Packages</file> files give the size (in
10359 bytes, expressed in decimal) and MD5 checksum of the
10360 file(s) which make(s) up a binary package in the
10361 distribution. If the package is split into several parts
10362 the values for the parts are listed in order, separated by
10367 <sect1 id="pkg-f-Status">
10368 <heading><tt>Status</tt></heading>
10371 This field in <prgn>dpkg</prgn>'s status file records
10372 whether the user wants a package installed, removed or
10373 left alone, whether it is broken (requiring
10374 re-installation) or not and what its current state on the
10375 system is. Each of these pieces of information is a
10380 <sect1 id="pkg-f-Config-Version">
10381 <heading><tt>Config-Version</tt></heading>
10384 If a package is not installed or not configured, this
10385 field in <prgn>dpkg</prgn>'s status file records the last
10386 version of the package which was successfully
10391 <sect1 id="pkg-f-Conffiles">
10392 <heading><tt>Conffiles</tt></heading>
10395 This field in <prgn>dpkg</prgn>'s status file contains
10396 information about the automatically-managed configuration
10397 files held by a package. This field should <em>not</em>
10398 appear anywhere in a package!
10403 <heading>Obsolete fields</heading>
10406 These are still recognized by <prgn>dpkg</prgn> but should
10407 not appear anywhere any more.
10409 <taglist compact="compact">
10411 <tag><tt>Revision</tt></tag>
10412 <tag><tt>Package-Revision</tt></tag>
10413 <tag><tt>Package_Revision</tt></tag>
10415 The Debian revision part of the package version was
10416 at one point in a separate control file field. This
10417 field went through several names.
10420 <tag><tt>Recommended</tt></tag>
10421 <item>Old name for <tt>Recommends</tt>.</item>
10423 <tag><tt>Optional</tt></tag>
10424 <item>Old name for <tt>Suggests</tt>.</item>
10426 <tag><tt>Class</tt></tag>
10427 <item>Old name for <tt>Priority</tt>.</item>
10436 <appendix id="pkg-conffiles">
10437 <heading>Configuration file handling (from old Packaging Manual)</heading>
10440 <prgn>dpkg</prgn> can do a certain amount of automatic
10441 handling of package configuration files.
10445 Whether this mechanism is appropriate depends on a number of
10446 factors, but basically there are two approaches to any
10447 particular configuration file.
10451 The easy method is to ship a best-effort configuration in the
10452 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10453 handle updates. If the user is unlikely to want to edit the
10454 file, but you need them to be able to without losing their
10455 changes, and a new package with a changed version of the file
10456 is only released infrequently, this is a good approach.
10460 The hard method is to build the configuration file from
10461 scratch in the <prgn>postinst</prgn> script, and to take the
10462 responsibility for fixing any mistakes made in earlier
10463 versions of the package automatically. This will be
10464 appropriate if the file is likely to need to be different on
10468 <sect><heading>Automatic handling of configuration files by
10473 A package may contain a control area file called
10474 <tt>conffiles</tt>. This file should be a list of filenames
10475 of configuration files needing automatic handling, separated
10476 by newlines. The filenames should be absolute pathnames,
10477 and the files referred to should actually exist in the
10482 When a package is upgraded <prgn>dpkg</prgn> will process
10483 the configuration files during the configuration stage,
10484 shortly before it runs the package's <prgn>postinst</prgn>
10489 For each file it checks to see whether the version of the
10490 file included in the package is the same as the one that was
10491 included in the last version of the package (the one that is
10492 being upgraded from); it also compares the version currently
10493 installed on the system with the one shipped with the last
10498 If neither the user nor the package maintainer has changed
10499 the file, it is left alone. If one or the other has changed
10500 their version, then the changed version is preferred - i.e.,
10501 if the user edits their file, but the package maintainer
10502 doesn't ship a different version, the user's changes will
10503 stay, silently, but if the maintainer ships a new version
10504 and the user hasn't edited it the new version will be
10505 installed (with an informative message). If both have
10506 changed their version the user is prompted about the problem
10507 and must resolve the differences themselves.
10511 The comparisons are done by calculating the MD5 message
10512 digests of the files, and storing the MD5 of the file as it
10513 was included in the most recent version of the package.
10517 When a package is installed for the first time
10518 <prgn>dpkg</prgn> will install the file that comes with it,
10519 unless that would mean overwriting a file already on the
10524 However, note that <prgn>dpkg</prgn> will <em>not</em>
10525 replace a conffile that was removed by the user (or by a
10526 script). This is necessary because with some programs a
10527 missing file produces an effect hard or impossible to
10528 achieve in another way, so that a missing file needs to be
10529 kept that way if the user did it.
10533 Note that a package should <em>not</em> modify a
10534 <prgn>dpkg</prgn>-handled conffile in its maintainer
10535 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10536 the user confusing and possibly dangerous options for
10537 conffile update when the package is upgraded.</p>
10540 <sect><heading>Fully-featured maintainer script configuration
10545 For files which contain site-specific information such as
10546 the hostname and networking details and so forth, it is
10547 better to create the file in the package's
10548 <prgn>postinst</prgn> script.
10552 This will typically involve examining the state of the rest
10553 of the system to determine values and other information, and
10554 may involve prompting the user for some information which
10555 can't be obtained some other way.
10559 When using this method there are a couple of important
10560 issues which should be considered:
10564 If you discover a bug in the program which generates the
10565 configuration file, or if the format of the file changes
10566 from one version to the next, you will have to arrange for
10567 the postinst script to do something sensible - usually this
10568 will mean editing the installed configuration file to remove
10569 the problem or change the syntax. You will have to do this
10570 very carefully, since the user may have changed the file,
10571 perhaps to fix the very problem that your script is trying
10572 to deal with - you will have to detect these situations and
10573 deal with them correctly.
10577 If you do go down this route it's probably a good idea to
10578 make the program that generates the configuration file(s) a
10579 separate program in <file>/usr/sbin</file>, by convention called
10580 <file><var>package</var>config</file> and then run that if
10581 appropriate from the post-installation script. The
10582 <tt><var>package</var>config</tt> program should not
10583 unquestioningly overwrite an existing configuration - if its
10584 mode of operation is geared towards setting up a package for
10585 the first time (rather than any arbitrary reconfiguration
10586 later) you should have it check whether the configuration
10587 already exists, and require a <tt>--force</tt> flag to
10588 overwrite it.</p></sect>
10591 <appendix id="pkg-alternatives"><heading>Alternative versions of
10592 an interface - <prgn>update-alternatives</prgn> (from old
10597 When several packages all provide different versions of the
10598 same program or file it is useful to have the system select a
10599 default, but to allow the system administrator to change it
10600 and have their decisions respected.
10604 For example, there are several versions of the <prgn>vi</prgn>
10605 editor, and there is no reason to prevent all of them from
10606 being installed at once, each under their own name
10607 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10608 Nevertheless it is desirable to have the name <tt>vi</tt>
10609 refer to something, at least by default.
10613 If all the packages involved cooperate, this can be done with
10614 <prgn>update-alternatives</prgn>.
10618 Each package provides its own version under its own name, and
10619 calls <prgn>update-alternatives</prgn> in its postinst to
10620 register its version (and again in its prerm to deregister
10625 See the man page <manref name="update-alternatives"
10626 section="8"> for details.
10630 If <prgn>update-alternatives</prgn> does not seem appropriate
10631 you may wish to consider using diversions instead.</p>
10634 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10635 package's version of a file (from old Packaging Manual)
10639 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10640 when it reinstalls the package it belongs to, and to have it
10641 put the file from the package somewhere else instead.
10645 This can be used locally to override a package's version of a
10646 file, or by one package to override another's version (or
10647 provide a wrapper for it).
10651 Before deciding to use a diversion, read <ref
10652 id="pkg-alternatives"> to see if you really want a diversion
10653 rather than several alternative versions of a program.
10657 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10658 and updated by a special program <prgn>dpkg-divert</prgn>.
10659 Please see <manref name="dpkg-divert" section="8"> for full
10660 details of its operation.
10664 When a package wishes to divert a file from another, it should
10665 call <prgn>dpkg-divert</prgn> in its preinst to add the
10666 diversion and rename the existing file. For example,
10667 supposing that a <prgn>smailwrapper</prgn> package wishes to
10668 install a wrapper around <file>/usr/sbin/smail</file>:
10670 dpkg-divert --package smailwrapper --add --rename \
10671 --divert /usr/sbin/smail.real /usr/sbin/smail
10672 </example> The <tt>--package smailwrapper</tt> ensures that
10673 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10674 can bypass the diversion and get installed as the true version.
10675 It's safe to add the diversion unconditionally on upgrades since
10676 it will be left unchanged if it already exists, but
10677 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10678 message, make the command conditional on the version from which
10679 the package is being upgraded:
10681 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10682 dpkg-divert --package smailwrapper --add --rename \
10683 --divert /usr/sbin/smail.real /usr/sbin/smail
10685 </example> where <tt>1.0-2</tt> is the version at which the
10686 diversion was first added to the package. Running the command
10687 during abort-upgrade is pointless but harmless.
10691 The postrm has to do the reverse:
10693 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10694 dpkg-divert --package smailwrapper --remove --rename \
10695 --divert /usr/sbin/smail.real /usr/sbin/smail
10697 </example> If the diversion was added at a particular version, the
10698 postrm should also handle the failure case of upgrading from an
10699 older version (unless the older version is so old that direct
10700 upgrades are no longer supported):
10702 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10703 dpkg-divert --package smailwrapper --remove --rename \
10704 --divert /usr/sbin/smail.real /usr/sbin/smail
10706 </example> where <tt>1.02-2</tt> is the version at which the
10707 diversion was first added to the package. The postrm should not
10708 remove the diversion on upgrades both because there's no reason to
10709 remove the diversion only to immediately re-add it and since the
10710 postrm of the old package is run after unpacking so the removal of
10711 the diversion will fail.
10715 Do not attempt to divert a file which is vitally important for
10716 the system's operation - when using <prgn>dpkg-divert</prgn>
10717 there is a time, after it has been diverted but before
10718 <prgn>dpkg</prgn> has installed the new version, when the file
10719 does not exist.</p>
10724 <!-- Local variables: -->
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